Note: Descriptions are shown in the official language in which they were submitted.
CA 02307429 2000-OS-03
Coated Detergent Tablets
Field of the Invention
This invention relates generally to compact shaped bodies having
detersive properties. Such detersive shaped bodies include, for example,
laundry detergent tablets, tablets for dishwashing machines or for cleaning
hard surfaces, bleach tablets for use in washing or dishwashing machines,
water softening tablets or stain remover tablets. More particularly, the
present invention relates to laundry detergent tablets which are used for
washing laundry in domestic washing machines and which are referred to
in short as detergent tablets.
Background of the Invention
Detergent tablets are widely described in the prior-art literature and
are enjoying increasing popularity among consumers because they are
easy to dose. Tabletted detergents have a number of advantages over
powder-form detergents: they are easier to dose and handle and, by virtue
of their compact structure, have advantages in regard to storage and
transportation. As a result, detergent shaped bodies are also
comprehensively described in the patent literature. One problem which
repeatedly arises in the use of detergent tablets is the inadequate
disintegrating and dissolving rate of the tablets under in-use conditions.
Since sufficiently stable, i.e. dimensionally stable and fracture-resistant,
tablets can only be produced by applying relatively high pressures, the
ingredients of the tablet are heavily compacted so that disintegration of the
tablet in the wash liquor is delayed which results in excessively slow
release of the active substances in the washing process. The delayed
disintegration of the tablets has the further disadvantage that typical
detergent tablets cannot be flushed into the washing process from the
dispensing compartment of domestic washing machines because the
tablets do not disintegrate sufficiently quickly into secondary particles
which
are small enough to be flushed from the dispensing compartment into the
CA 02307429 2000-OS-03
2
drum of the washing machine. Another problem which occurs with
detergent tablets in particular lies in the friability of the tablets and
their
often inadequate resistance to abrasion. Thus, although sufficiently
fracture-resistant, i.e. hard, detergent tablets can be produced, they are
often not strong enough to withstand the loads encountered during
packaging, transportation and handling, i.e. impact and friction effects, so
that broken edges and signs of abrasion spoil the appearance of the tablet
or even lead to the complete destruction of its structure.
Many solutions have been developed in the prior art to overcome the
dichotomy between hardness, i.e. transportation and handling stability, and
easy disintegration of the tablets. One solution known in particular from the
field of pharmacy and extended to detergent tablets is to incorporate
certain disintegration aids which facilitate the access of water and which
swell on contact with water and effervesce or otherwise disintegrate. Other
solutions proposed in the patent literature are based on the compression of
premixes of certain particle sizes, the separation of individual ingredients
from certain other ingredients and the coating of individual ingredients or
the entire tablet with binders.
The coating of detergent tablets is the subject of certain patent
applications.
Thus, European patent applications EP 846 754, EP 846 755 and
EP 846 756 (Procter & Gamble) describe coated detergent tablets
comprising a "core" of compacted particulate detergent and a coating,
dicarboxylic acids, more particularly adipic acid, optionally containing other
ingredients, for example disintegration aids, being used as the coating
materials.
Coated detergent tablets are also the subject of European patent
application EP 716 144 (Unilever). According to the disclosure of this
document, the hardness of the tablets can be increased by a coating
without any adverse effect on the tablet disintegration and dissolving times.
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3
Film-forming substances, more particularly copolymers of acrylic acid and
malefic acid or sugars, are mentioned as coating materials.
The documents cited above contain little information on the
application of the coating. They also provide no particulars of the coating
thickness.
Whereas, according to the teaching of the first of the documents
cited above, far more than 5% by weight of the total weight of the coated
tablet consists of coating material, the figure is still at least 1 % by
weight
according to the teaching of the last of the cited documents. In addition,
the solutions proposed in the prior art also require individual wrapping of
the tablets. To this end, the tablets have to be wrapped in film as individual
tablets or as dosage units which may consist, for example, of two tablets to
ensure than the tablets retain their hardness and their fast disintegration
times in storage. Only after this individual wrapping of tablets can the pack
as a whole as supplied to the consumer be boxed.
Now, the problem addressed by the present invention was to provide
coated detergent tablets where the advantageous properties of relatively
high hardness values compared with short disintegration times would be
achieved with smaller quantities of coating materials, at most 1 % by weight
and, preferably, significantly less of the tablet as a whole being made up by
the coating material. In particular, the resistance of the tablets to impact
and friction would be further improved in relation to known tablets despite a
distinct reduction in the amount of coating material used. Ideally, the
coated tablets would be able to be supplied to the consumer with
minimized packaging, i.e. in more cost efficient individual packs or even
without such packs, without any adverse effect on the storage stability of
the tablets. Another problem addressed by the present invention was to
provide a simple and universally usable process for the production of such
coated tablets.
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4
Summary of the Invention
It has now been found that certain water-soluble polymers are
suitable for coating detergent tablets, even in extremely small quantities,
and provide them with advantageous properties.
Accordingly, the present invention relates to detergent tablets of
compacted particulate detergent containing builder(s), surfactants) and
optionally other detergent ingredients which are coated with a polymer or
polymer mixture, the polymer or at least 50% by weight of the polymer
mixture being selected from
a) water-soluble nonionic polymers from the group of
a1) polyvinyl pyrrolidones,
a2) vinyl pyrrolidone/vinyl ester copolymers,
a3) cellulose ethers
b) water-soluble amphoteric polymers from the group of
b1 ) alkyl acrylamide/acrylic acid copolymers,
b2) alkyl acrylamide/methacrylic acid copolymers,
b3) alkyl acrylamidelmethyl methacrylic acid copolymers,
b4) alkyl acrylamidelacrylic acidlalkylaminoalkyl (meth)acrylic acid co-
polymers,
b5) alkyl acrylamide/methacrylic acidlalkylaminoalkyl (meth)acrylic acid
copolymers,
b6) alkyl acrylamidelmethyl methacrylic acidlalkylaminoalkyl (meth)-
acrylic acid copolymers,
b7) alkyl acrylamidelalkyl methacrylate/alkylaminoethyl methacrylatel
alkyl methacrylate copolymers,
b8) copolymers of
b8i) unsaturated carboxylic acids,
b8ii) cationically derivatized unsaturated carboxylic acids,
CA 02307429 2000-OS-03
b8iii) optionally other ionic or nonionic monomers,
c) water-soluble zwitterionic polymers from the group of
c1) acrylamidoalkyl trialkylammonium chloridelacrylic acid copolymers
and alkali metal and ammonium salts thereof, ,
5 c2) acrylamidoalkyl trialkylammonium chloridelmethacrylic acid copoly-
mers and alkali metal and ammonium salts thereof,
c3) methacroyl ethyl betainelmethacrylate copolymers,
d) water-soluble anionic polymers from the group of
d1) vinyl acetatelcrotonic acid copolymers,
d2) vinyl pyrrolidonelvinyl acrylate copolymers,
d3) acrylic acidlethyl acrylate/N-tert.butyl acrylamide terpolymers,
d4) graft polymers of vinyl esters, esters of acrylic acid or methacrylic
acid individually or in admixture copolymerized with crotonic acid,
acrylic acid or methacrylic acid with polyalkylene oxides andlor
polyalkylene glycols,
d5) grafted and crosslinked copolymers from the copolymerization of
d5i) at least one monomer of the nonionic type,
d5ii) at least one monomer of the ionic type,
d5iii) polyethylene glycol and
d5iv) a crosslinking agent,
d6) copolymers obtained by copolymerization of at least one monomer
of each of the following three groups:
d6i) esters of unsaturated alcohols and short-chain saturated
carboxylic acids and/or esters of short-chain saturated
alcohols and unsaturated carboxylic acids,
d6ii) unsaturated carboxylic acids,
d6iii) esters of long-chain carboxylic acids and unsaturated
alcohols andlor esters of the carboxylic acids of group d6ii)
with saturated or unsaturated, linear or branched C8_,a
CA 02307429 2000-OS-03
6
alcohols,
d7) terpolymers of crotonic acid, vinyl acetate and an allyl or methallyl
este r,
d8) tetrapolymers and pentapolymers of
d8i) crotonic acid or allyloxyacetic acid,
d8ii) vinyl acetate or vinyl propionate,
d8iii) branched allyl or methallyl esters,
d8iv) vinyl ethers, vinyl esters or straight-chain allyl or methallyl
esters,
d9) crotonic acid copolymers with one or more monomers from the
group consisting of ethylene, vinyl benzene, vinyl methyl ether,
acrylamide and water-soluble salts thereof,
d10) terpolymers of vinyl acetate, crotonic acid and vinyl esters of a
saturated aliphatic monocarboxylic acid branched in the a-position,
e) water-soluble cationic polymers from the group of
e1) quaternized cellulose derivatives,
e2) polysiloxanes containing quaternary groups,
e3) cationic guar derivatives,
e4) polymeric dimethyl diallylammonium salts and copolymers thereof
with esters and amides of acrylic acid and methacrylic acid,
e5) copolymers of vinyl pyrrolidone with quaternized derivatives of
dialkylaminoacrylate and methacrylate,
e6) vinyl pyrrolidonelmethoimidazolinium chloride copolymers,
e7) quaternized polyvinyl alcohol,
e8) polymers known by the INCI names of polyquaternium 2,
polyquaternium 17, polyquaternium 18 and polyquaternium 27.
Water-soluble polymers in the context of the invention are polymers
of which more than 2.5% by weight are soluble in water at room
CA 02307429 2000-OS-03
7
temperature.
Detailed Description of the Invention
The detergent tablets according to the invention are coated with a
polymer or polymer mixture, the polymer (and hence the entire coating) or
at least 50% by weight of the polymer mixture (and hence at least 50% of
the coating) being selected from certain polymers. In this case, all the
coating or at least 50% of its weight consists of water-soluble polymers
from the group of nonionic, amphoteric, zwitterionic, anionic andlor cationic
polymers. These polymers are described in more detail in the following.
According to the invention, preferred water-soluble polymers are
nonionic. The following are examples of suitable nonionic polymers:
- Polyvinyl pyrrolidones which are marketed, for example, under the
name of Luviskol~ (BASF). Polyvinyl pyrrolidones are preferred
nonionic polymers for the purposes of the invention.
Polyvinyl pyrrolidones [poly(1-vinyl-2-pyrrolidinones)], PVPs for short,
are polymers corresponding to general formula (I):
CH-CH2
N ~ (I)
n
which are obtained by radical polymerization of 1-vinyl pyrrolidone by
solution or suspension polymerization using radical formers (peroxides,
azo compounds) as initiators. The ionic polymerization of the monomer
only gives products of low molecular weight. Commercially available
polyvinyl pyrrolidones have molecular weights of about 2500 to 750,000
g/mole which are characterized by expressing the K values and -
CA 02307429 2000-OS-03
depending on their K value - have glass transition temperatures of 130
to 175°C. They are marketed as white hygroscopic powders or as
aqueous solutions. Polyvinyl pyrrolidones are readily soluble in water
and in a number of organic solvents (alcohols, ketones, glacial acetic
acid, chlorinated hydrocarbons, phenols, etc.).
- Vinyl pyrrolidone/vinyl acetate copolymers which are marketed, for
example under the registered name of Luviskol~ (BASF). Luviskol~ VA
64. and Luviskol~ VA 73, both vinyl pyrrolidonelvinyl acetate
copolymers, are particularly preferred nonionic polymers.
The vinyl ester polymers are polymers obtainable from vinyl esters
containing a group corresponding to formula (II):
-CH2-CH-
O
C
// \
O R (11)
as the characteristic basic unit of the macromolecules. Of these, the
vinyl acetate polymers (R = CH3) with polyvinyl acetates, as by far the
most important representatives, have the greatest commercial
significance. The polymerization of the vinyl esters is carried out by
various radical polymerization processes (solution polymerization,
suspension polymerization, emulsion polymerization, bulk poly-
merization). Copolymers of vinyl acetate with vinyl pyrrolidone contain
monomer units corresponding to formulae (I) and (II).
- Cellulose ethers, such as hydroxypropyl cellulose, hydroxyethyl
cellulose and methyl hydroxypropyl cellulose, which are marketed for
CA 02307429 2000-OS-03
9
example under the registered names of Culminal~ and Benecel~
(AQUALON).
Cellulose ethers correspond to general formula (III):
R~CHZ O R
'~O O RO p_
RQ o d (Ill)
R RO HZ
in which R represents H or an alkyl, alkenyl, alkinyl, aryl or alkylaryl
group. In preferred products, at least one R in formula (III) stands for
-CH2CH2CH2-OH or -CH2CH2-OH. On an industrial scale, cellulose
ethers are produced by etherification of alkali metal cellulose (for
example with ethylene oxide). Cellulose ethers are characterized by the
average degree of substitution DS or the molar degree of substitution
MS which indicate how many hydroxy groups of an anhydroglucose unit
of the cellulose have reacted with the etherifying agent or how many
moles of the etherifying agent on average have been added onto one
anhydroglucose unit. Hydroxyethyl celluloses are soluble in water
where they have a DS of about 0.6 or higher or an MS of about 1 or
higher. Commercially available hydroxyethyl or hydroxypropyl
celluloses have degrees of substitution of 0.85 to 1.35 (DS) or 1.5 to 3
(MS). Hydroxyethyl and hydroxypropyl celluloses are marketed as
yellowish-white, odorless and tasteless powders with various degrees of
polymerization. Hydroxyethyl and hydroxypropyl celluloses are soluble
in cold and hot water and in certain (water-containing) organic solvents,
but are insoluble in most (water-free) organic solvents. Their aqueous
solutions are relatively non-sensitive to changes in pH or to the addition
of an electrolyte.
Other polymers suitable for the purposes of the invention are water-
CA 02307429 2000-OS-03
soluble "amphopolymers". "Amphopolymers" is the generic term for
amphoteric polymers, i.e. polymers which contain both free amino groups
and free -COOH or -S03H groups in the molecule and which are capable of
forming inner salts, zwitterionic polymers which contain quaternary
5 ammonium groups and -COO- or -S03 groups in the molecule, and for
polymers which contain -COOH or -S03H groups and quaternary
ammonium groups. One example of an amphopolymer suitable for use in
accordance with the invention is the acrylic resin obtainable under the
name of Amphomer~, which is a copolymer of tert.butyl aminoethyl
10 methacrylate, N-(1,1,3,3-tetramethylbutyl)acrylamide and two or more
monomers from the group consisting of acrylic acid, methacrylic acid and
simple esters thereof. Other preferred amphopolymers consist of
unsaturated carboxylic acids (for example acrylic and methacrylic acid),
cationically derivatized unsaturated carboxylic acids (for example
acrylamidopropyl trimethyl ammonium chloride) and optionally other ionic
or nonionic monomers as known, for example, from DE-A-39 29 973 and
the prior art literature cited therein. According to the invention,
terpolymers
of acrylic acid, methyl acrylate and methacrylamidopropyl trimonium
chloride, which are commercially available under the name of Merquat~
2001 N, are particularly preferred amphopolymers. Other suitable
amphoteric polymers are, for example, the octyl acrylamide/methyl meth-
acrylate/tert.butylaminoethyl methacrylate/2-hydroxypropyl methacrylate
copolymers obtainable under the names of Amphomer~ and Amphomer~
LV-71 (DELFT NATIONAL).
Suitable zwitterionic polymers are, for example, the polymers
disclosed in German patent applications DE 39 29 973, DE 21 50 557, DE
28 17 369 and DE 37 08 451. Acrylamidopropyl trimethylammonium
chloride/acrylic acid or methacrylic acid copolymers and alkali metal and
ammonium salts thereof are preferred zwitterionic polymers. Other suitable
zwitterionic polymers are methacroyl ethyl betaine/methacrylate copoly-
CA 02307429 2000-OS-03
11
mers which are commercially obtainable under the name of Amersette~
(AMERCHOL).
Anionic polymers suitable for the purposes of the present invention
include:
- Vinyl acetatelcrotonic acid copolymers which are marketed, for
example, under the names of Resyn~ (NATIONAL STARCH), Luviset~
(BASF) and Gafset~ (GAF).
Besides monomer units corresponding to formula (II) above, these
polymers also contain monomer units corresponding to general formula
(IV):
[-CH(CH3)-CH(COOH)-]~ (IV)
- Vinyl pyrrolidonelvinyl acrylate copolymers obtainable, for example,
under the registered name of Luviflex~ (BASF). A preferred polymer is
the vinyl pyrrolidonelacrylate terpolymer obtainable under the name of
Luviflex~ VBM-35 (BASF).
- Acrylic acid/ethylacrylatelN-tert.butyl acrylamide terpolymers which are
marketed, for example, under the name of Ultrahold~ strong (BASF).
- Graft polymers of vinyl esters, esters of acrylic acid or methacrylic acid
individually or in admixture copolymerized with crotonic acid, acrylic
acid or methacrylic acid with polyalkylene oxides andlor polyalkylene
glycols.
Corresponding grafted polymers of vinyl esters, esters of acrylic acid or
methacrylic acid individually or in admixture with other copolymerizable
compounds on polyalkylene glycols are obtained by high-temperature
polymerization in homogeneous phase by stirring the polyalkylene
CA 02307429 2000-OS-03
12
glycols into the monomers, i.e. vinyl esters, esters of acrylic or
methacrylic acid, in the presence of radical formers.
Suitable vinyl esters are, for example, vinyl acetate, vinyl propionate,
vinyl butyrate, vinyl benzoate while suitable esters of acrylic or meth-
s acrylic acid are those obtainable with low molecular weight aliphatic
alcohols, i.e. in particular ethanol, propanol, isopropanol, 1-butanol, 2-
butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 2-
pentanol, 3-pentanol, 2,2-dimethyl-1-propanol, 3-methyl-1-butanol; 3-
methyl-2-butanol, 2-methyl-2-butanol, 2-methyl-1-butanol, 1-hexanol.
Suitable polyalkylene glycols are, in particular, polyethylene glycols and
polypropylene glycols. Polymers of ethylene glycol which correspond to
general formula (V):
H-(O-CH2-CH2)~-OH (V)
where n may assume values of 1 (ethylene glycol) to several thousand.
Various nomenclatures are used for polyethylene glycols which can
lead to confusion. It is common practice to indicate the mean relative
molecular weight after the initials "PEG", so that "PEG 200"
characterizes a polyethylene glycol having a relative molecular weight
of about 190 to about 210. Cosmetic ingredients are covered by
another nomenclature in which the initials PEG are followed by a
hyphen and the hyphen is in turn directly followed by a number which
corresponds to the index n in general formula V above. Under this
nomenclature (so-called INCI nomenclature, CTFA International
Cosmetic Ingredient Dictionary and Handbook, 5th Edition, The
Cosmetic, Toiletry and Fragrance Association, Washington, 1997),
PEG-4, PEG-6, PEG-8, PEG-9, PEG-10, PEG-12, PEG-14 and PEG-
16, for example, may be used. Polyethylene glycols are commercially
obtainable, for example, under the names of Carbowax~ PEG 200
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13
(Union Carbide), Emkapol~ 200 (ICI Americas), Lipoxol~ 200 MED
(HULS America), Polyglycol~ E-200 (Dow Chemical), Alkapol~ PEG
300 (Rhone-Poulenc), Lutrol~ E300 (BASF) and the corresponding
commercial names with higher numbers.
Polypropylene glycols (PPGs) are polymers of propylene glycol which
correspond to general formula (VI):
H-(O-CH-CH2)~-OH (VI)
CH3
where n may assume a value of 1 (propylene glycol) to several
thousand. Di-, tri- and tetrapropylene glycol, i.e. representatives where
n = 2, 3 and 4 in formula VI, are of particular commercial significance.
More particularly, the vinyl acetate copolymers grafted onto poly-
ethylene glycols and the polymers of vinyl acetate and crotonic acid
grafted onto polyethylene glycols may be used.
- Grafted and crosslinked copolymers from the copolymerization of
i) at least one monomer of the nonionic type,
ii) at least one monomer of the ionic type,
iii) polyethylene glycol and
iv) a crosslinking agent.
The polyethylene glycol used has a molecular weight of 200 to several
million and preferably in the range from 300 to 30,000.
The nonionic monomers may be of various types, among which the
following are preferred: vinyl acetate, vinyl stearate, vinyl laurate, vinyl
propionate, allyl stearate, allyl laurate, diethyl maleate, allyl acetate,
methyl methacrylate, cetyl vinyl ether, stearyl vinyl ether and 1-hexene.
The nonionic monomers may also be of various types, among which
crotonic acid, allyloxyacetic acid, vinyl acetic acid, malefic acid, acrylic
CA 02307429 2000-OS-03
14
acid and methacrylic acid are present with particular advantage in the
graft polymers.
Preferred crosslinking agents are ethylene glycol dimethacrylate, diallyl
phthalate, ortho-, meta- and para-divinyl benzene, tetraallyloxy ethane
and polyallyl saccharoses containing 2 to 5 allyl groups per molecule of
saccharin.
The grafted and crosslinked copolymers described above are preferably
formed from:
i) 5 to 85% by weight of at least one monomer of the nonionic type,
ii) 3 to 80% by weight of at least one monomer of the ionic type,
iii) 2 to 50% by weight and preferably 5 to 30% by weight of polyethyl-
ene glycol and
iv) 0.1 to 8% by weight of a crosslinking agent, the percentage of the
crosslinking agent being determined by the ratio of the total weights
of i), ii) and iii).
Copolymers obtained by copolymerization of at least one monomer of
each of the following three groups:
i) esters of unsaturated alcohols and short-chain saturated carboxylic
acids andlor esters of short-chain saturated alcohols and
unsaturated carboxylic acids,
ii) unsaturated carboxylic acids,
iii) esters of long-chain carboxylic acids and unsaturated alcohols
andlor esters of the carboxylic acids of group ii) with saturated or
unsaturated, linear or branched Ca_~$ alcohol.
Short-chain carboxylic acids or alcohols in the context of the present
invention are understood to be those containing 1 to 8 carbon atoms,
the carbon chains of these compounds optionally being interrupted by
two-bond hetero groups, such as -O-, -NH-, -S-.
CA 02307429 2000-OS-03
- Terpolymers of crotonic acid, vinyl acetate and an allyl or methallyl
ester.
These terpolymers contain monomer units corresponding to general
formulae (II) and (IV) (see above) and monomer units of one or more
5 allyl or methallyl esters corresponding to formula (VII):
R' R3
R2-C-C(O)-O-CH2-C=CH2 (VI I)
CH3
where R3 represents -H or -CH3, R2 represents -CH3 or -CH(CH3)2 and
R' represents -CH3 or is a saturated, linear or branched C~_6 alkyl group
and the sum of the carbon atoms in the substituents R' and R2 is
preferably 7, 6, 5, 4, 3 or 2.
The terpolymers mentioned above preferably result from the
copolymerization of 7 to 12% by weight of crotonic acid, 65 to 86% by
weight and preferably 71 to 83% by weight of vinyl acetate and 8 to
20% by weight and preferably 10 to 17% by weight of allyl or methallyl
esters corresponding to formula (VII).
- Tetrapolymers and pentapolymers of
i) crotonic acid or allyloxyacetic acid,
ii) vinyl acetate or vinyl propionate,
iii) branched ally) or methallyl esters,
iv) vinyl ethers, vinyl esters or straight-chain allyl or methallyl esters.
- Crotonic acid copolymers with one or more monomers from the group
consisting of ethylene, vinyl benzene, vinyl methyl ether, acrylamide
and water-soluble salts thereof.
CA 02307429 2000-OS-03
16
- Terpolymers of vinyl acetate, crotonic acid and vinyl esters of a
saturated aliphatic monocarboxylic acid branched in the a-position.
Other polymers usable with advantage as part of the coating are
cationic polymers. Among the cationic polymers, permanently cationic
polymers are preferred. In the context of the invention, "permanently
cationic" polymers are polymers which contain a cationic group irrespective
of the pH value of the detergent (i.e. both the coating and the tablet). Such
polymers are generally polymers which contain a quaternary nitrogen atom,
for example in the form of an ammonium group.
The following are examples of preferred cationic polymers:
- Quaternized cellulose derivatives commercially obtainable under the
names of Celquat~ and Polymer JR~. The compounds Celquat~ H
100, Celquat~ L 200 and Polymer JR~ 400 are preferred quaternized
cellulose derivatives.
- Polysiloxanes containing quaternary groups such as, for example, the
commercially available products Q2-7224 (manufacturer: Dow Corning;
a stabilized trimethyl silylamodimethicone), Dow Corning~ 929
Emulsion (containing a hydroxylamino-modified silicone which is also
known as amodimethicone), SM-2059 (manufacturer: General Electric),
SLM-55067 (manufacturer: Wacker) and Abil~-Quat 3270 and 3272
(manufacturer: Th. Goldschmidt; diquaternary polydimethyl siloxanes,
quaternium-80).
- Cationic guar derivatives such as, in particular, the products marketed
under the names of Cosmedia~Guar and Jaguar~.
- Polymeric dimethyl diallylammonium salts and copolymers thereof with
CA 02307429 2000-OS-03
17
esters and amides of acrylic acid and methacrylic acid. The products
commercially obtainable under the names of Merquat~ 100
(poly(dimethyl diallylammonium chloride)) and Merquat~ 550 (dimethyl
diallylammonium chloridelacrylamide copolymer) are examples of such
cationic polymers.
- Copolymers of vinyl pyrrolidone with quaternized derivatives of dialkyl
aminoacrylate and methacrylate, such as for example vinyl pyrrolidone/
dimethylaminomethacrylate copolymers quaternized with diethyl sulfate.
Compounds such as these are commercially available under the names
of Gafquat~ 734 and Gafquat~ 755.
- Vinyl pyrrolidonelmethoimidazolinium chloride copolymers as marketed
under the name of Luviquat~.
- Quaternized polyvinyl alcohol
and the polymers containing quaternary nitrogen atoms in the main
polymer chain known by the names of
- polyquaternium 2,
- polyquaternium 17,
- polyquaternium 18 and
- polyquaternium 27.
The names of the above-mentioned polymers are based on the so-called
INCI nomenclature: particulars can be found in the CTFA International
Cosmetic Ingredient Dictionary and Handbook, 5t" Edition, The Cosmetic,
Toiletry and Fragrance Association, Washington, 1997, to which reference
is expressly made here.
According to the invention, preferred cationic polymers are
CA 02307429 2000-OS-03
18
quaternized cellulose derivatives and polymeric dimethyl diallylammonium
salts and copolymers thereof. Cationic cellulose derivatives, more
particularly the commercial product Polymer~ JR 400, are most particularly
preferred cationic polymers.
The detergent tablets coated in accordance with the invention have
distinctly improved properties even with small amounts of coating material.
In a preferred embodiment of the invention, the quantity of coating material
makes up less than 1 % by weight, preferably less than 0.5% by weight and
more preferably less than 0.25% by weight of the total weight of the coated
tablet. Accordingly, detergent tablets where the ratio by weight of uncoated
tablet to coating is greater than 100:1, preferably greater than 250:1 and
more preferably greater than 500:1 are preferred embodiments of the
present invention.
By virtue of the small quantities in which the polymers mentioned
above form a high-strength and advantageous coating around the pre
compressed detergent tablets, it is possible to achieve coating thicknesses
which are small by comparison with the dimensions of the tablets. In
preferred detergent tablets, the thickness of the coating on the tablet is
between 0.1 and 150 Nm, preferably between 0.5 and 100 Nm and more
preferably between 5 and 50 Nm.
In order to make the coating even more resistant to mechanical
stressing, polyurethanes may be incorporated therein. Polyurethanes
provide the coating with elasticity and stability and, after the above
mentioned quantity of water-soluble polymer, may make up as much as
50% by weight of the coating.
In the context of the present invention, polyurethanes are insoluble
in water if less than 2.5% by weight dissolves in water at room temperature.
The polyurethanes consist of at least two different types of
monomer, namely:
- a compound (A) containing at least 2 active hydrogen atoms per
CA 02307429 2000-OS-03
19
molecule and
- a diisocyanate or polyisocyanate (B).
The compounds (A) may be, for example, diols, triols, diamines,
triamines, polyetherols and polyesterols. The compounds containing more
than 2 active hydrogen atoms are normally used in only small quantities in
combination with a large excess of compounds containing 2 active
hydrogen atoms.
Examples of compounds (A) are ethylene glycol, 1,2- and 1,3-pro-
pylene glycol, butylene glycols, di-, tri-, tetra- and poly-ethylene and -pro-
pylene glycols, copolymers of lower alkylene oxides, such as ethylene
oxide, propylene oxide and butylene oxide, ethylenediamine, propylenedi-
amine, 1,4-diaminobutane, hexamethylenediamine and a,c~-diamines
based on long-chain alkanes or polyalkylene oxides.
According to the invention, polyurethanes in which the compounds
(A) are diols, triols and polyetherols can be preferred. In some cases,
polyethylene glycols and polypropylene glycols in particular with molecular
weights in the range from 200 to 3000 and more particularly in the range
from 1600 to 2500 have proved to be particularly suitable. Polyesterols are
normally obtained by modifying the compound (A) with dicarboxylic acids,
such as phthalic acid, isophthalic acid and adipic acid.
The compounds (B) used are mainly hexamethylene diisocyanate,
2,4- and 2,6-toluene diisocyanate, 4,4'-methylene di(phenylisocyanate)
and, more particularly, isophorone diisocyanate. These compounds may
be described by the following general formula:
O=C=N-R4-N=C=O (VIII)
in which R4 is a connecting group of carbon atoms, for example a
methylene, ethylene, propylene, butylene, pentylene, hexylene etc. group.
In the above-mentioned and, industrially, most widely used hexamethylene
CA 02307429 2000-OS-03
diisocyanate (HMDI), R4 = (CHZ)s; in 2,4- and 2,6-toluene diisocyanate
(TDI), R4 = CsH3-CH3); in 4,4'-methylene di(phenylisocyanate) (MDI), R4 =
C6H4-CH2-C6H4 and, in isophorone diisocyanate, R4 = the isophorone
residue (3,5,5-trimethyl-2-cyclohexenone).
5 In addition, the polyurethanes used in accordance with the invention
may contain such structural units as, for example, diamines as chain
extenders and hydroxycarboxylic acids. Dialkylol carboxylic acids such as,
for example, dimethylol propionic acid are particularly suitable hydroxycar-
boxylic acids. So far as the other structural units are concerned, it makes
10 no difference in principle whether they are nonionic, anionic or cationic.
Further information on the structure and production of the
polyurethanes can be found in the articles in the relevant reference books,
such as Rompps Chemie-Lexikon and Ullmanns Enzyklopadie der
technischen Chemie.
15 In many cases, polyurethanes which may be characterized as
follows have proved to be particularly suitable for the purposes of the
present invention:
- solely aliphatic groups in the molecule,
- no free isocyanate groups in the molecule,
20 - polyether and polyester polyurethanes,
- anionic groups in the molecule.
In addition, it has proved to be of advantage so far as the production
of the coated detergent tablets according to the invention is concerned if
the polyurethanes are not directly mixed with the other components, but
instead are introduced in the form of aqueous dispersions. Such disper-
sions normally have a solids content of about 20 to 50% and, more
particularly, about 35 to 45% and are also commercially obtainable.
According to the invention, detergent tablets of which the coating
contains polyurethanes in quantities of 5 to 50% by weight, preferably 7.5
to 40% by weight and more preferably 10 to 30% by weight, based on the
CA 02307429 2000-OS-03
21
coating, in addition to the polymers mentioned are preferred.
The constituents of the coating of the tablets according to the
invention are described in detail in the foregoing. The constituents of the
tablets per se, i.e. the uncoated tablets, are described in the following.
These tablets are referred to hereinafter partly as "basic tablets" in order
to
make a verbal distinction from the term "tablet" for the detergent tablets
coated in accordance with the invention and partly by the general term
"tablet". Since the subject of the present invention are basic tablets
provided with a coating, the observations made in the following in reference
to the basic tablet naturally apply equally to detergent tablets according to
the invention which satisfy the corresponding requirements and vice versa.
The basic tablets contain builders) and surfactants) as essential
ingredients. The basic tablets according to the invention may contain any
of the builders typically used in detergents, i.e. in particular zeolites,
silicates, carbonates, organic co-builders and also - providing there are no
ecological objections to their use - the phosphates.
Suitable crystalline layer-form sodium silicates correspond to the
general formula NaMSiX02X+~y H20, where M is sodium or hydrogen, x is a
number of 1.9 to 4 and y is a number of 0 to 20, preferred values for x
being 2, 3 or 4. Crystalline layer silicates such as these are described, for
example, in European patent application EP-A-0 164 514. Preferred
crystalline layer silicates corresponding to the above formula are those in
which M is sodium and x assumes the value 2 or 3. Both Vii- and 8-sodium
disilicates Na2Si205y H20 are particularly preferred, ~-sodium disilicate
being obtainable, for example, by the process described in International
patent application WO-A- 91!08171.
Other useful builders are amorphous sodium silicates with a
modulus (Na20:Si02 ratio) of 1:2 to 1:3.3, preferably 1:2 to 1:2.8 and more
preferably 1:2 to 1:2.6 which dissolve with delay and exhibit multiple wash
cycle properties. The delay in dissolution in relation to conventional
CA 02307429 2000-OS-03
22
amorphous sodium silicates can have been obtained in various ways, for
example by surface treatment, compounding, compacting or by overdrying.
In the context of the invention, the term "amorphous" is also understood to
encompass "X-ray amorphous". In other words, the silicates do not
produce any of the sharp X-ray reflexes typical of crystalline substances in
X-ray diffraction experiments, but at best one or more maxima of the
scattered X-radiation which have a width of several degrees of the
diffraction angle. However, particularly good builder properties may even
be achieved where the silicate particles produce crooked or even sharp
diffraction maxima in electron diffraction experiments. This may be
interpreted to mean that the products have microcrystalline regions
between 10 and a few hundred nm in size, values of up to at most 50 nm
and, more particularly, up to at most 20 nm being preferred. So-called X-
ray amorphous silicates such as these, which also dissolve with delay in
relation to conventional waterglasses, are described for example in
German patent application DE-A-44 00 024. Compacted amorphous
silicates, compounded amorphous silicates and overdried X-ray-amorphous
silicates are particularly preferred.
The finely crystalline, synthetic zeolite containing bound water used
in accordance with the invention is preferably zeolite A andlor zeolite P.
Zeolite MAP~ (Crosfield) is a particularly preferred P-type zeolite.
However, zeolite X and mixtures of A, X andlor P are also suitable.
According to the invention, it is also preferred to use, for example, a co-
crystallizate of zeolite X and zeolite A (ca. 80% by weight zeolite X) which
is marketed by CONDEA Augusta S.p.A. under the name of VEGOBOND
AX~ and which may be described by the following formula:
nNa20 ~ (1-n)K20 ~ AI203 ~ (2 - 2.5)Si02 ~ (3.5 - 5.5) H20.
The zeolite may be used both as a builder in a granular compound and as
CA 02307429 2000-OS-03
23
a kind of "powder" to be applied to the entire mixture to be tabletted, both
routes normally being used to incorporate the zeolite in the premix.
Suitable zeolites have a mean particle size of less than 10 pm (volume
distribution, as measured by the Coulter Counter Method) and contain
preferably 18 to 22% by weight and more preferably 20 to 22% by weight of
bound water.
The generally known phosphates may of course also be used as
builders providing their use should not be avoided on ecological grounds.
Among the large number of commercially available phosphates, alkali
metal phosphates have the greatest importance in the detergent industry,
pentasodium triphosphate and pentapotassium triphosphate (sodium and
potassium tripolyphosphate) being particularly preferred.
"Alkali metal phosphates" is the collective term for the alkali metal
(more particularly sodium and potassium) salts of the various phosphoric
acids, including metaphosphoric acids (HP03)~ and orthophosphoric acid
(H3P04) and representatives of higher molecular weight. The phosphates
combine several advantages: they act as alkalinity sources, prevent lime
deposits on machine parts and lime incrustations in fabrics and, in addition,
contribute towards the cleaning effect.
Sodium dihydrogen phosphate (NaH2P04) exists as the dehydrate
(density 1.91 gcm-3, melting point 60°) and as the monohydrate (density
2.04 gcm~3). Both salts are white readily water-soluble powders which, on
heating, lose the water of crystallization and, at 200°C, are converted
into
the weakly acidic diphosphate (disodium hydrogen diphosphate,
Na2H2P207) and, at higher temperatures, into sodium trimetaphosphate
(Na3P309) and Maddrell's salt (see below). NaH2P04 shows an acidic
reaction. It is formed by adjusting phosphoric acid with sodium hydroxide
to a pH value of 4.5 and spraying the resulting "mash". Potassium
dihydrogen phosphate (primary or monobasic potassium phosphate,
potassium biphosphate, KDP), KH2P04, is a white salt with a density of
CA 02307429 2000-OS-03
24
2.33 gcm-3, has a melting point of 253° [decomposition with formation
of
potassium polyphosphate (KP03)X] and is readily soluble in water.
Disodium hydrogen phosphate (secondary sodium phosphate),
Na2HP04, is a colorless, readily water-soluble crystalline salt. It exists in
water-free form and with 2 moles (density 2.066 gcm-3, water loss at
95°), 7
moles (density 1.68 gcm~3, melting point 48° with loss of 5 H20) and 12
moles of water (density 1.52 gcm-3, melting point 35° with loss of 5
H20),
becomes water-free at 100° and, on fairly intensive heating, is
converted
into the diphosphate Na4P207. Disodium hydrogen phosphate is prepared
by neutralization of phosphoric acid with soda solution using phenol-
phthalein as indicator. Dipotassium hydrogen phosphate (secondary or
dibasic potassium phosphate), KZHP04, is an amorphous white salt which
is readily soluble in water.
Trisodium phosphate, tertiary sodium phosphate, Na3P04, consists
of colorless crystals which have a density of 1.62 gcm~3 and a melting point
of 73-76° (decomposition) as the dodecahydrate, a melting point of
100° as
the decahydrate (corresponding to 19-20% P205) and a density of 2.536
gcm-3 in water-free form (corresponding to 39-40% P205). Trisodium
phosphate is readily soluble in water through an alkaline reaction and is
prepared by concentrating a solution of exactly 1 mole of disodium
phosphate and 1 mole of NaOH by evaporation. Tripotassium phosphate
(tertiary or tribasic potassium phosphate), K3P04, is a white deliquescent
granular powder with a density of 2.56 gcm~, has a melting of 1340° and
is
readily soluble in water through an alkaline reaction. It is formed, for
example, when Thomas slag is heated with coal and potassium sulfate.
Despite their higher price, the more readily soluble and therefore highly
effective potassium phosphates are often preferred to corresponding
sodium compounds in the detergent industry.
Tetrasodium diphosphate (sodium pyrophosphate), Na4P20~, exists
in water-free form (density 2.534 gcm-3, melting point 988°, a figure
of 880°
CA 02307429 2000-OS-03
has also been mentioned) and as the decahydrate (density 1.815 - 1.836
gcm-3, melting point 94° with loss of water). Both substances are
colorless
crystals which dissolve in water through an alkaline reaction. Na4P207 is
formed when disodium phosphate is heated to >200° or by reacting
5 phosphoric acid with soda in a stoichiometric ratio and spray-drying the
solution. The decahydrate complexes heavy metal salts and hardness
salts and, hence, reduces the hardness of water. Potassium diphosphate
(potassium pyrophosphate), K4P207, exists in the form of the trihydrate and
is a colorless hygroscopic powder with a density of 2.33 gcm~ which is
10 soluble in water, the pH value of a 1 % solution at 25° being 10.4.
Relatively high molecular weight sodium and potassium phosphates
are formed by condensation of NaH2P04 or KH2P04. They may be divided
into cyclic types, namely the sodium and potassium metaphosphates, and
chain types, the sodium and potassium polyphosphates. The chain types
15 in particular are known by various different names: fused or calcined
phosphates, Graham's salt, Kurrol's salt and Maddrell's salt. All higher
sodium and potassium phosphates are known collectively as condensed
phosphates.
The industrially important pentasodium triphosphate, Na5P30~o
20 (sodium tripolyphosphate), is a non-hygroscopic white water-soluble salt
which crystallizes without water or with 6 H20 and which has the general
formula Na0-[P(O)(ONa)-O]~-Na where n = 3. Around 17 g of the salt free
from water of crystallization dissolve in 100 g of water at room temperature,
around 20 g at 60° and around 32 g at 100°. After heating of the
solution
25 for 2 hours to 100°, around 8% orthophosphate and 15% diphosphate
are
formed by hydrolysis. In the preparation of pentasodium triphosphate,
phosphoric acid is reacted with soda solution or sodium hydroxide in a
stoichiometric ratio and the solution is spray-dried. Similarly to Graham's
salt and sodium diphosphate, pentasodium triphosphate dissolves many
insoluble metal compounds (including lime soaps, etc.). Pentapotassium
CA 02307429 2000-OS-03
26
triphosphate, K5P30~o (potassium tripolyphosphate), is marketed for
example in the form of a 50% by weight solution (> 23% P205, 25% K20).
The potassium polyphosphates are widely used in the detergent industry.
Sodium potassium tripolyphosphates, which may also be used in
accordance with the invention, also exist. They are formed for example
when sodium trimetaphosphate is hydrolyzed with KOH:
(NaP03)3 + 2 KOH ~ Na3K2P30~o + H20
According to the invention, they may be used in exactly the same
way as sodium tripolyphosphate, potassium tripolyphosphate or mixtures
thereof. Mixtures of sodium tripolyphosphate and sodium potassium
tripolyphosphate or mixtures of potassium tripolyphosphate and sodium
potassium tripolyphosphate or mixtures of sodium tripolyphosphate and
potassium tripolyphosphate and sodium potassium tripolyphosphate may
also be used in accordance with the invention.
Organic cobuilders suitable for use in the basic tablets according to
the invention are, in particular, polycarboxylateslpolycarboxylic acids,
polymeric polycarboxylates, aspartic acid, polyacetals, dextrins, other
organic cobuilders (see below) and phosphonates. These classes of
substances are described in the following.
Useful organic builders are, for example, the polycarboxylic acids
usable, for example, in the form of their sodium salts, polycarboxylic acids
in this context being understood to be carboxylic acids which bear more
than one acid function. Examples of such carboxylic acids are citric acid,
adipic acid, succinic acid, glutaric acid, malic acid, tartaric acid, malefic
acid,
fumaric acid, sugar acids, aminocarboxylic acids, nitrilotriacetic acid (NTA),
providing their use is not ecologically unsafe, and mixtures thereof.
Preferred salts are the salts of the polycarboxylic acids, such as citric
acid,
adipic acid, succinic acid, glutaric acid, tartaric acid, sugar acids and
CA 02307429 2000-OS-03
27
mixtures thereof.
The acids per se may also be used. Besides their builder effect, the
acids also typically have the property of an acidifying component and,
hence, also serve to establish a relatively low and mild pH value in
detergents. Citric acid, succinic acid, glutaric acid, adipic acid, gluconic
acid and mixtures thereof are particularly mentioned in this regard.
Other suitable builders are polymeric polycarboxylates such as, for
example, the alkali metal salts of polyacrylic or polymethacrylic acid, for
example those with a relative molecular weight of 500 to 70,000 glmole.
The molecular weights mentioned in this specification for polymeric
polycarboxylates are weight-average molecular weights MW of the particular
acid form which, basically, were determined by gel permeation
chromatography (GPC) using a UV detector. The measurement was
carried out against an external polyacrylic acid standard which provides
realistic molecular weight values by virtue of its structural similarity to
the
polymers investigated. These values differ distinctly from the molecular
weights measured against polystyrene sulfonic acids as standard. The
molecular weights measured against polystyrene sulfonic acids are
generally higher than the molecular weights mentioned in this specification.
Particularly suitable polymers are polyacrylates which preferably
have a molecular weight of 2,000 to 20,000 g/mole. By virtue of their
superior solubility, preferred representatives of this group are the short-
chain polyacrylates which have molecular weights of 2,000 to 10,000
g/mole and, more particularly, 3,000 to 5,000 glmole.
Also suitable are copolymeric polycarboxylates, particularly those of
acrylic acid with methacrylic acid and those of acrylic acid or methacrylic
acid with malefic acid. Acrylic acid/maleic acid copolymers containing 50 to
90% by weight of acrylic acid and 50 to 10% by weight of malefic acid have
proved to be particularly suitable. Their relative molecular weights, based
on the free acids, are generally in the range from 2,000 to 70,000 glmole,
CA 02307429 2000-OS-03
28
preferably in the range from 20,000 to 50,000 glmole and more preferably
in the range from 30,000 to 40,000 glmole.
The (co)polymeric polycarboxylates may be used either in powder
form or in the form of an aqueous solution. The content of (co)polymeric
polycarboxylates in the detergent is preferably from 0.5 to 20% by weight
and more preferably from 3 to 10% by weight.
In order to improve solubility in water, the polymers may also contain
allyl sulfonic acids, such as allyloxybenzene sulfonic acid and methallyl
sulfonic acid, as monomer.
Other particularly preferred polymers are biodegradable polymers of
more than two different monomer units, for example those which contain
salts of acrylic acid and malefic acid and vinyl alcohol or vinyl alcohol
derivatives as monomers or those which contain salts of acrylic acid and 2-
alkylallyl sulfonic acid and sugar derivatives as monomers.
Other preferred copolymers are those which are described in
German patent applications DE-A-43 03 320 and DE-A-44 17 734 and
which preferably contain acrolein and acrylic acid/acrylic acid salts or
acrolein and vinyl acetate as monomers.
Other preferred builders are polymeric aminodicarboxylic acids, salts
or precursors thereof. Particular preference is attributed to polyaspartic
acids or salts and derivatives thereof which, according to German patent
application DE-A-195 40 086, are also said to have a bleach-stabilizing
effect in addition to their co-builder properties.
Other suitable builders are polyacetals which may be obtained by
reaction of dialdehydes with polyol carboxylic acids containing 5 to 7
carbon atoms and at least 3 hydroxyl groups. Preferred polyacetals are
obtained from dialdehydes, such as glyoxal, glutaraldehyde, terephthal-
aldehyde and mixtures thereof and from polyol carboxylic acids, such as
gluconic acid andlor glucoheptonic acid.
Other suitable organic builders are dextrins, for example oligomers
CA 02307429 2000-OS-03
29
or polymers of carbohydrates which may be obtained by partial hydrolysis
of starches. The hydrolysis may be carried out by standard methods, for
example acid- or enzyme-catalyzed methods. The end products are
preferably hydrolysis products with average molecular weights of 400 to
500,000 glmole. A polysaccharide with a dextrose equivalent (DE) of 0.5 to
40 and, more particularly, 2 to 30 is preferred, the DE being an accepted
measure of the reducing effect of a polysaccharide by comparison with
dextrose which has a DE of 100. Both maltodextrins with a DE of 3 to 20
and dry glucose sirups with a DE of 20 to 37 and also so-called yellow
dextrins and white dextrins with relatively high molecular weights of 2,000
to 30,000 g/mole may be used.
The oxidized derivatives of such dextrins are their reaction products
with oxidizing agents which are capable of oxidizing at least one alcohol
function of the saccharide ring to the carboxylic acid function. Dextrins thus
oxidized and processes for their production are known, for example, from
European patent applications EP-A-0 232 202, EP-A-0 427 349, EP-A-0
472 042 and EP-A-0 542 496 and from International patent applications
WO 92118542, WO 93/08251, WO 93116110, WO 94!28030, WO 95/07303,
WO 95112619 and WO 95120608. An oxidized oligosaccharide
corresponding to German patent application DE-A-196 00 018 is also
suitable. A product oxidized at C6 of the saccharide ring can be particularly
advantageous.
Other suitable co-builders are oxydisuccinates and other derivatives
of disuccinates, preferably ethylenediamine disuccinate. Ethylenediamine
N,N'-disuccinate (EDDS) is preferably used in the form of its sodium or
magnesium salts. Glycerol disuccinates and glycerol trisuccinates are also
preferred in this connection. The quantities used in zeolite-containing
and/or silicate-containing formulations are from 3 to 15% by weight.
Other useful organic co-builders are, for example, acetylated
hydroxycarboxylic acids and salts thereof which may optionally be present
CA 02307429 2000-OS-03
in lactone form and which contain at least 4 carbon atoms, at least one
hydroxy group and at most two acid groups. Co-builders such as these are
described, for example, in International patent application WO 95120029.
Another class of substances with co-builder properties are the
5 phosphonates, more particularly hydroxyalkane and aminoalkane phos-
phonates. Among the hydroxyalkane phosphonates, 1-hydroxyethane-1,1-
diphosphonate (HEDP) is particularly important as a co-builder. It is
preferably used in the form of the sodium salt, the disodium salt showing a
neutral reaction and the tetrasodium salt an alkaline reaction (pH 9).
10 Preferred aminoalkane phosphonates are ethylenediamine tetramethylene
phosphonate (EDTMP), diethylenetriamine pentamethylenephosphonate
(DTPMP) and higher homologs thereof. They are preferably used in the
form of the neutrally reacting sodium salts, for example as the hexasodium
salt of EDTMP or as the hepta- and octasodium salts of DTPMP. Of the
15 phosphonates, HEDP is preferably used as a builder. In addition, the
aminoalkane phosphonates have a pronounced heavy metal binding
capacity. Accordingly, it can be of advantage, particularly where the
detergents also contain bleach, to use aminoalkane phosphonates, more
particularly DTPMP, or mixtures of the phosphonates mentioned.
20 In addition, any compounds capable of forming complexes with
alkaline earth metal ions may be used as co-builders.
The quantity of builder used is normally between 10 and 70% by
weight, preferably between 15 and 60% by weight and more preferably
between 20 and 50% by weight. The quantity of builder used is again
25 dependent upon the particular application envisaged, so that bleach tablets
can contain larger quantities of builders (for example between 20 and 70%
by weight, preferably between 25 and 65% by weight and more preferably
between 30 and 55% by weight) than, for example, laundry detergent
tablets (normally 10 to 50% by weight, preferably 12.5 to 45% by weight
30 and more preferably 17.5 to 37.5% by weight).
CA 02307429 2000-OS-03
31
Preferred basic tablets additionally contain one or more
surfactant(s). Anionic, nonionic, cationic and/or amphoteric surfactants or
mixtures thereof may be used in the basic tablets according to the
invention. Mixtures of anionic and nonionic surfactants are preferred from
the performance point of view. The total surfactant content of the tablets is
between 5 and 60% by weight, based on tablet weight, surfactant contents
above 15% by weight being preferred.
The anionic surfactants used are, for example, those of the sulfonate
and sulfate type. Preferred surfactants of the sulfonate type are C9_~3 alkyl
benzenesulfonates, olefin sulfonates, i.e. mixtures of alkene and hydroxy
alkane sulfonates; and the disulfonates obtained, for example, from 02_18
monoolefins with an internal or terminal double bond by sulfonation with
gaseous sulfur trioxide and subsequent alkaline or acidic hydrolysis of the
sulfonation products. Other suitable surfactants of the sulfonate type are
the alkane sulfonates obtained from C~2_~$ alkanes, for example by
sulfochlorination or sulfoxidation and subsequent hydrolysis or
neutralization. The esters of a-sulfofatty acids (ester sulfonates), for
example the a-sulfonated methyl esters of hydrogenated coconut, palm
kernel or tallow acids, are also suitable.
Other suitable anionic surfactants are sulfonated fatty acid glycerol
esters, i.e. the monoesters, diesters and triesters and mixtures thereof
which are obtained where production is carried out by esterification of a
monoglycerol with 1 to 3 moles of fatty acid or in the transesterification of
triglycerides with 0.3 to 2 moles of glycerol. Preferred sulfonated fatty acid
glycerol esters are the sulfonation products of saturated C6_22 fatty acids,
for example caproic acid, caprylic acid, capric acid, myristic acid, lauric
acid, palmitic acid, stearic acid or behenic acid.
Preferred alk(en)yl sulfates are the alkali metal salts and, in
particular, the sodium salts of the sulfuric acid semiesters of C~2_~8 fatty
alcohols, for example coconut alcohol, tallow alcohol, lauryl, myristyl, cetyl
CA 02307429 2000-OS-03
32
or stearyl alcohol, or C~o_2o oxoalcohols and the corresponding semiesters
of secondary alcohols with the same chain length. Other preferred
alk(en)yl sulfates are those with the chain length mentioned which contain
a synthetic, linear alkyl chain based on a petrochemical and which are
similar in their degradation behavior to the corresponding compounds
based on oleochemical raw materials. C~2_~6 alkyl sulfates and C~2_~5 alkyl
sulfates and also C,4_,5 alkyl sulfates are particularly preferred from the
washing performance point of view. Other suitable anionic surfactants are
2,3-alkyl sulfates which may be produced, for example, in accordance with
US 3,234,258 or US 5,075,041 and which are commercially obtainable as
products of the Shell Oil Company under the name of DAN~.
The sulfuric acid monoesters of linear or branched C~_2~ alcohols
ethoxylated with 1 to 6 moles of ethylene oxide, such as 2-methyl-branched
C9_" alcohols containing on average 3.5 moles of ethylene oxide (EO) or
C,2-is fatty alcohols containing 1 to 4 EO, are also suitable. In view of
their
high foaming capacity, they are normally used in only relatively small
quantities, for example in quantities of 1 to 5% by weight, in dishwashing
detergents.
Other suitable anionic surfactants are the salts of alkyl sulfosuccinic
acid which are also known as sulfosuccinates or as sulfosuccinic acid
esters and which represent monoesters andlor diesters of sulfosuccinic
acid with alcohols, preferably fatty alcohols and, more particularly,
ethoxylated fatty alcohols. Preferred sulfosuccinates contain C8_~8 fatty
alcohol molecules or mixtures thereof. Particularly preferred
sulfosuccinates contain a fatty alcohol molecule derived from ethoxylated
fatty alcohols which, considered in isolation, represent nonionic surfactants
(for a description, see below). Of these sulfosuccinates, those of which the
fatty alcohol molecules are derived from narrow-range ethoxylated fatty
alcohols are particularly preferred. Alk(en)yl succinic acid preferably
containing 8 to 18 carbon atoms in the alk(en)yl chain or salts thereof may
CA 02307429 2000-OS-03
33
also be used.
Other suitable anionic surfactants are, in particular, soaps. Suitable
soaps are, in particular, saturated fatty acid soaps, such as the salts of
lauric acid, myristic acid, palmitic acid, stearic acid, hydrogenated erucic
acid and behenic acid, and soap mixtures derived in particular from natural
fatty acids, for example coconut, palm kernel or tallow acids.
The anionic surfactants, including the soaps, may be present in the
form of their sodium, potassium or ammonium salts and as soluble salts of
organic bases, such as mono-, di- or triethanolamine. The anionic
surfactants are preferably present in the form of their sodium or potassium
salts and, more preferably, in the form of their sodium salts.
Preferred nonionic surfactants are alkoxylated, advantageously
ethoxylated, more especially primary alcohols preferably containing 8 to 18
carbon atoms and, on average, 1 to 12 moles of ethylene oxide (EO) per
mole of alcohol, in which the alcohol group may be linear or, preferably,
methyl-branched in the 2-position or may contain linear and methyl-
branched groups in the form of the mixtures typically present in oxoalcohol
groups. However, alcohol ethoxylates containing linear groups of alcohols
of native origin with 12 to 18 carbon atoms, for example coconut, palm,
tallow or oleyl alcohol, and on average 2 to 8 EO per mole of alcohol are
particularly preferred. Preferred ethoxylated alcohols include, for example,
C~2_~4 alcohols containing 3 EO or 4 EO, C9_» alcohol containing 7 EO,
C~3_~5 alcohols containing 3 EO, 5 EO, 7 EO or 8 EO, C~2_~8 alcohols
containing 3 EO, 5 EO or 7 EO and mixtures thereof, such as mixtures of
C~2_~4 alcohol containing 3 EO and C~2_~8 alcohol containing 5 EO. The
degrees of ethoxylation mentioned represent statistical mean values which,
for a special product, can be a whole number or a broken number.
Preferred alcohol ethoxylates have a narrow homolog distribution (narrow
range ethoxylates, NRE). In addition to these nonionic surfactants, fatty
alcohols containing more than 12 EO may also be used, examples
CA 02307429 2000-OS-03
34
including tallow fatty alcohol containing 14 EO, 25 EO, 30 EO or 40 EO.
Suitable other nonionic surfactants are alkyl glycosides with the
general formula RO(G)X where R is a primary, linear or methyl-branched,
more particularly 2-methyl-branched, aliphatic radical containing 8 to 22
and preferably 12 to 18 carbon atoms and G stands for a glycose unit
containing 5 or 6 carbon atoms, preferably glucose. The degree of
oligomerization x, which indicates the distribution of monoglycosides and
oligoglycosides, is a number of 1 to 10 and preferably 1.2 to 1.4.
Another class of preferred nonionic surfactants which may be used
either as sole nonionic surfactant or in combination with other nonionic
surfactants are alkoxylated, preferably ethoxylated or ethoxylated and
propoxylated, fatty acid alkyl esters preferably containing 1 to 4 carbon
atoms in the alkyl chain, more especially the fatty acid methyl esters which
are described, for example, in Japanese patent application JP 581217598
or which are preferably produced by the process described in International
patent application WO-A-90!13533.
Nonionic surfactants of the amine oxide type, for example N-
coconutalkyl-N,N-dimethylamine oxide and N-tallowalkyl-N,N-dihydroxy-
ethylamine oxide, and the fatty acid alkanolamide type are also suitable.
The quantity in which these nonionic surfactants are used is preferably no
more than the quantity in which the ethoxylated fatty alcohols are used
and, more preferably, no more than half that quantity.
Other suitable surfactants are polyhydroxyfatty acid amides
corresponding to formula (IX):
R'
R-CO-N-[Z] ( IX)
in which RCO is an aliphatic acyl group containing 6 to 22 carbon atoms,
R~ is hydrogen, an alkyl or hydroxyalkyl group containing 1 to 4 carbon
atoms and [Z] is a linear or branched polyhydroxyalkyl group containing 3
CA 02307429 2000-OS-03
to 10 carbon atoms and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid
amides are known substances which may normally be obtained by
reductive amination of a reducing sugar with ammonia, an alkylamine or an
alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl
5 ester or a fatty acid chloride.
The group of polyhydroxyfatty acid amides also includes compounds
corresponding to formula (X):
10 R'-O-R2
R-CO-N-[Z] (X)
in which R is a linear or branched alkyl or alkenyl group containing 7 to 12
15 carbon atoms, R' is a linear, branched or cyclic alkyl group or an aryl
group
containing 2 to 8 carbon atoms and R2 is a linear, branched or cyclic alkyl
group or an aryl group or an oxyalkyl group containing 1 to 8 carbon atoms,
C~~ alkyl or phenyl groups being preferred, and [Z] is a linear polyhydroxy-
alkyl group, of which the alkyl chain is substituted by at least two hydroxyl
20 groups, or alkoxylated, preferably ethoxylated or propoxylated, derivatives
of that group.
[Z] is preferably obtained by reductive amination of a reduced sugar,
for example glucose, fructose, maltose, lactose, galactose, mannose or
xylose. The N-alkoxy- or N-aryloxy-substituted compounds may then be
25 converted into the required polyhydroxyfatty acid amides by reaction with
fatty acid methyl esters in the presence of an alkoxide as catalyst, for
example in accordance with the teaching of International patent application
WO-A-95107331.
According to the invention, preferred basic tablets contain anionic
30 and nonionic surfactant(s). Performance-related advantages can arise out
of certain quantity ratios in which the individual classes of surfactants are
used.
CA 02307429 2000-OS-03
36
For example, particularly preferred basic tablets are characterized in
that the ratio of anionic surfactants) to nonionic surfactants) is from 10:1
to 1:10, preferably from 7.5:1 to 1:5 and more preferably from 5:1 to 1:2.
Other preferred detergent tablets contain anionic andlor nonionic
surfactants) and have total surfactant contents above 2.5% by weight,
preferably above 5% by weight and more preferably above 10% by weight,
based on tablet weight. Other particularly preferred detergent tablets are
characterized in that they contain surfactant(s), preferably anionic andlor
nonionic surfactant(s), in quantities of 5 to 40% by weight, preferably 7.5 to
35% by weight, more preferably 10 to 30% by weight and most preferably
12.5 to 25% by weight, based on the weight of the tablet.
It can be of advantage from the performance point of view if certain
classes of surfactants are missing from certain phases of the basic tablets
or from the entire tablet, i.e. from every phase. In another important
embodiment of the present invention, therefore, at least one phase of the
tablets is free from nonionic surfactants.
Conversely, a positive effect can also be obtained through the
presence of certain surfactants in individual phases or in the tablet as a
whole, i.e. in every phase. Introducing the alkyl polyglycosides described
above has proved to be of particular advantage, so that basic tablets in
which at least one phase of the tablet contains alkyl polyglycosides are
preferred.
As with the nonionic surfactants, the omission of anionic surfactants
from individual phases or from all phases can result in basic tablets which
are more suitable for certain applications. Accordingly, detergent tablets
where at least one phase of the tablet is free from anionic surfactants are
also possible in accordance with the present invention.
In order to facilitate the disintegration of heavily compacted tablets,
disintegration aids, so-called tablet disintegrators, may be incorporated in
them to shorten their disintegration times. According to Rompp (9th
CA 02307429 2000-OS-03
37
Edition, Vol. 6, page 4440) and Voigt "Lehrbuch der pharmazeutischen
Technologie" (6th Edition, 1987, pages 182-184), tablet disintegrators or
disintegration accelerators are auxiliaries which promote the rapid
disintegration of tablets in water or gastric juices and the release of the
pharmaceuticals in an absorbable form.
These substances, which are also known as "disintegrators" by
virtue of their effect, are capable of undergoing an increase in volume on
contact with water so that, on the one hand, their own volume is increased
(swelling) and, on the other hand, a pressure can be generated through the
release of gases which causes the tablet to disintegrate into relatively small
particles. Well-known disintegrators are, for example, carbonate/citric acid
systems, although other organic acids may also be used. Swelling
disintegration aids are, for example, synthetic polymers, such as polyvinyl
pyrrolidone (PVP), or natural polymers and modified natural substances,
such as cellulose and starch and derivatives thereof, alginates or casein
derivatives.
Preferred basic tablets contain 0.5 to 10% by weight, preferably 3 to
7% by weight and more preferably 4 to 6% by weight of one or more
disintegration aids, based on the weight of the tablet.
According to the invention, preferred disintegrators are cellulose-
based disintegrators, so that preferred basic tablets contain a cellulose-
based disintegrator in quantities of 0.5 to 10% by weight, preferably 3 to
7% by weight and more preferably 4 to 6% by weight. Pure cellulose has
the formal empirical composition (C6H~pO5)n and, formally, is a ~3-1,4-
polyacetal of cellobiose which, in turn, is made up of two molecules of
glucose. Suitable celluloses consist of ca. 500 to 5000 glucose units and,
accordingly, have average molecular weights of 50,000 to 500,000.
According to the invention, cellulose derivatives obtainable from cellulose
by polymer-analog reactions may also be used as cellulose-based
disintegrators. These chemically modified celluloses include, for example,
CA 02307429 2000-OS-03
38
products of esterification or etherification reactions in which hydroxy
hydrogen atoms have been substituted. However, celluloses in which the
hydroxy groups have been replaced by functional groups that are not
attached by an oxygen atom may also be used as cellulose derivatives.
The group of cellulose derivatives includes, for example, alkali metal
celluloses, carboxymethyl cellulose (CMC), cellulose esters and ethers and
aminocelluloses. The cellulose derivatives mentioned are preferably not
used on their own, but rather in the form of a mixture with cellulose as
cellulose-based disintegrators. The content of cellulose derivatives in
mixtures such as these is preferably below 50% by weight and more
preferably below 20% by weight, based on the cellulose-based
disintegrator. In one particularly preferred embodiment, pure cellulose free
from cellulose derivatives is used as the cellulose-based disintegrator.
The cellulose used as disintegration aid is preferably not used in
fine-particle form, but is converted into a coarser form, for example by
granulation or compacting, before it is added to and mixed with the
premixes to be tabletted. Detergent tablets which contain granular or
optionally co-granulated disintegrators are described in German patent
applications DE 197 09 991 (Stefan Herzog) and DE 197 10 254 (Henkel)
and in International patent application WO 98140463 (Henkel). Further
particulars of the production of granulated, compacted or co-granulated
cellulose disintegrators can also be found in these patent applications. The
particle sizes of such disintegration aids is mostly above 200 Nm,
preferably at least 90% by weight of the particles being between 300 and
1600 Nm in size and, more particularly, between 400 and 1200 Nm in size.
According to the invention, the above-described relatively coarse-particle
cellulose-based disintegrators described in detail in the cited patent
applications are preferably used as disintegration aids and are
commercially obtainable, for example under the name of Arbocel~ TF-30
HG from Rettenmaier.
CA 02307429 2000-OS-03
39
Microcrystalline cellulose may be used as another cellulose-based
disintegration aid or as part of such a component. This microcrystalline
cellulose is obtained by partial hydrolysis of the celluloses under conditions
which only attack and completely dissolve the amorphous regions (ca. 30%
of the total cellulose mass) of the celluloses, but leave the crystalline
regions (ca. 70%) undamaged. Subsequent de-aggregation of the
microfine celluloses formed by hydrolysis provides the microcrystalline
celluloses which have primary particle sizes of ca. 5 Nm and which can be
compacted, for example, to granules with a mean particle size of 200 Nm.
According to the invention, preferred detergent tablets aditionally
contain a disintegration aid, preferably a cellulose-based disintegration aid,
preferably in granular, co-granulated or compacted form, in quantities of 0.5
to 10% by weight, preferably in quantities of 3 to 7% by weight and more
preferably in quantities of 4 to 6% by weight, based on tablet weight,
preferred disintegration aids having mean particle sizes above 300 Nm,
preferably above 400 Nm and more preferably above 500 Nm.
Besides the ingredients mentioned thus far (builder, surfactant and
disintegration aid), the detergent tablets according to the invention may
contain other typical detergent ingredients from the group of bleaching
agents, bleach activators, dyes, perfumes, optical brighteners, enzymes,
foam inhibitors, silicone oils, redeposition inhibitors, discoloration
inhibitors,
dye transfer inhibitors and corrosion inhibitors.
To develop the required bleaching effect, the detergent tablets
according to the invention may contain bleaching agents. The usual
bleaching agents from the group consisting of sodium perborate
monohydrate, sodium perborate tetrahydrate and sodium percarbonate
have proved to be particularly useful in this regard.
"Sodium percarbonate" is a non-specific term used for sodium
carbonate peroxohydrates which, strictly speaking, are not "percarbonates"
(i.e. salts of percarbonic acid), but hydrogen peroxide adducts with sodium
CA 02307429 2000-OS-03
carbonate. The commercial material has the mean composition 2 Na2C03
3 H202 and, accordingly, is not a peroxycarbonate. Sodium percarbonate
forms a white water-soluble powder with a density of 2.14 gcm-3 which
readily decomposes into sodium carbonate and bleaching or oxidizing
5 oxygen.
Sodium carbonate peroxohydrate was obtained for the first time in
1899 by precipitation with ethanol from a solution of sodium carbonate in
hydrogen peroxide, but was mistakenly regarded as peroxycarbonate. It
was only in 1909 that the compound was recognised as a hydrogen
10 peroxide addition compound. Nevertheless, the historical name "sodium
percarbonate" has been adopted in practice.
On an industrial scale, sodium percarbonate is mainly produced by
precipitation from aqueous solution (so-called wet process). In this pro-
cess, aqueous solutions of sodium carbonate and hydrogen peroxide are
15 combined and the sodium percarbonate is precipitated by salting-out
agents (mainly sodium chloride), crystallization aids (for example polyphos-
phates, polyacrylates) and stabilizers (for example Mg2+ ions). The
precipitated salt which still contains 5 to 12% by weight of mother liquor is
then removed by centrifuging and dried at 90°C in fluidized bed dryers.
20 The bulk density of the end product can vary between 800 and 1200 gll
according to the production process. In general, the percarbonate is
stabilized by an additional coating. Coating processes and materials are
widely described in the patent literature. Basically, any commercially
available percarbonate types as marketed, for example, by Solvay Interox,
25 Degussa, Kemira and Akzo may be used in accordance with the present
invention.
So far as the bleaching agents used are concerned, the content of
these substances in the tablets is determined by the application envisaged
for the tablets. Whereas conventional heavy-duty detergents in tablet form
30 contain between 5 and 30% by weight, preferably between 7.5 and 25% by
CA 02307429 2000-OS-03
41
weight and more preferably between 12.5 and 22.5% by weight of
bleaching agent, bleach or bleach booster tablets contain between 15 and
50% by weight, preferably between 22.5 and 45% by weight and more
preferably between 30 and 40% by weight.
In addition to the bleaching agents used, the detergent tablets
according to the invention may contain bleach activators) which represents
a preferred embodiment of the present invention. Bleach activators are
incorporated in detergents in order to obtain an improved bleaching effect
at washing temperatures of 60°C or lower. According to the invention,
compounds which form aliphatic peroxocarboxylic acids preferably
containing 1 to 10 carbon atoms and more preferably 2 to 4 carbon atoms
andlor optionally substituted perbenzoic acid under perhydrolysis
conditions may be used as bleach activators. Suitable bleach activators
are substances which contain O- andlor N-acyl groups with the number of
carbon atoms indicated and/or optionally substituted benzoyl groups.
Preferred additional bleach activators are polyacylated alkylenediamines,
more especially tetraacetyl ethylenediamine (TAED), acylated triazine
derivatives, more particularly 1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine
(DADHT), acylated glycol urils, more particularly tetraacetyl glycol uril
(TAGU), N-acylimides, more particularly N-nonanoyl succinimide (NOSI),
acylated phenol sulfonates, more particularly n-nonanoyl- or isononanoyl-
oxybenzenesulfonate (n- or iso-NOBS), carboxylic anhydrides, more
especially phthalic anhydride, acylated polyhydric alcohols, more especially
triacetin, ethylene glycol diacetate and 2,5-diacetoxy-2,5-dihydrofuran.
In addition to or instead of the conventional bleach activators, so-
called bleach catalysts may also be incorporated in the tablets. Bleach
catalysts are bleach-boosting transition metal salts or transition metal
complexes such as, for example, Mn-, Fe-, Co-, Ru- or Mo-salen
complexes or carbonyl complexes. Mn-, Fe-, Co-, Ru-, Mo-, Ti-, V- and Cu-
complexes with N-containing tripod ligands and Co-, Fe-, Cu- and Ru-
CA 02307429 2000-OS-03
42
ammine complexes may also be used as bleach catalysts.
If the tablets according to the invention contain bleach activators,
they contain between 0.5 and 30% by weight, preferably between 1 and
20% by weight and more preferably between 2 and 15% by weight - based
on the tablet as a whole - of one or more bleach activators or bleach
catalysts. These quantities may vary according to the application
envisaged for the tablets. Thus, in typical heavy-duty detergent tablets,
bleach activator contents of 0.5 to 10% by weight, preferably 2 to 8% by
weight and more preferably 4 to 6% by weight are normal whereas bleach
tablets can have much higher contents, for example between 5 and 30% by
weight, preferably between 7.5 and 25% by weight and more preferably
between 10 and 20% by weight. The expert is not restricted in his freedom
of formulation and is able in this way to produce laundry detergent tablets,
dishwasher tablets or bleach tablets with a stronger or weaker bleaching
effect by varying the contents of bleach activator and bleaching agent.
A particularly preferred bleach activator is N,N,N',N'-tetraacetyl
ethylenediamine which is widely used in laundry/dishwasher detergents.
Accordingly, preferred detergent tablets are characterized in that they
contain tetraacetyl ethylenediamine in the quantities mentioned above as
bleach activator.
Besides the ingredients mentioned (bleaching agent, bleach
activator, builder, surfactant and disintegration aid), the detergent tablets
according to the invention may contain other ingredients typical of
detergents from the group of dyes, perfumes, optical brighteners, enzymes
foam inhibitors, silicone oils, redeposition inhibitors, discoloration
inhibitors,
dye transfer inhibitors and corrosion inhibitors.
In order to improve their aesthetic impression, the detergents
according to the invention may be colored with suitable dyes. Preferred
dyes, which are not difficult for the expert to choose, have high stability in
storage, are not affected by the other ingredients of the detergents or by
CA 02307429 2000-OS-03
43
light and do not have any pronounced substantivity for textile fibers so as
not to color them.
Any dyes which can be destroyed by oxidation in the washing
process and mixtures thereof with suitable blue dyes, so-called blueing
agents, are preferably used in the detergent tablets according to the
invention. It has proved to be of advantage to use dyes which are soluble
in water or - at room temperature - in liquid organic substances. Suitable
dyes are, for example, anionic dyes, for example anionic nitroso dyes. One
possible dye is, for example, naphthol green (Color Index (CI) Part 1: Acid
Green 1; Part 2: 10020), which is commercially available for example as
Basacid~ Grun 970 from BASF, Ludwigshafen, and mixtures thereof with
suitable blue dyes. Other suitable dyes are Pigmosol~ Blau 6900 (CI
74160), Pigmosol~ Grun 8730 (CI 74260), Basonyl~ Rot 545 FL (CI
45170), Sandolan~ Rhodamin EB 400 (CI 45100), Basacid~ Gelb 094 (CI
47005), Sicovit~ Patentblau 85 E 131 (CI 42051), Acid Blue 183 (CAS
12217-22-0, CI Acid Blue 183), Pigment Blue 15 (CI 74160), Supranol~
Blau GLW (CAS 12219-32-8, CI Acid Blue 221 )), Nylosan~ Gelb N-7GL
SGR (CAS 61814-57-1, CI Acid Yellow 218) and/or Sandolan~ Blau (CI
Acid Blue 182, CAS 12219-26-0).
In selecting the dye, it is important to ensure that the dye does not
have an excessive affinity for the textile surfaces and, in particular, for
synthetic fibers. Another factor to be taken into account in the selection of
suitable dyes is that dyes differ in their stability to oxidation. Generally
speaking, water-insoluble dyes are more stable to oxidation than water-
soluble dyes. The concentration of the dye in the detergents varies
according to its solubility and hence its sensitivity to oxidation. In the
case
of readily water-soluble dyes, for example the above-mentioned Basacid~
Grun and Sandolan~ Blau, dye concentrations in the range from a few 10-2
to 10-3 % by weight are typically selected. By contrast, in the case of the
pigment dyes which are particularly preferred for their brilliance, but which
CA 02307429 2000-OS-03
44
are less readily soluble in water, for example the above-mentioned
Pigmosol~ dyes, suitable concentrations of the dye in detergents are
typically of the order of a few 10-3 to 10-4 % by weight.
The tablets may contain derivatives of diaminostilbenedisulfonic acid
or alkali metal salts thereof as optical brighteners. Suitable optical
brighteners are, for example, salts of 4,4'-bis-(2-anilino-4-morpholino-1,3,5-
triazinyl-6-amino)-stilbene-2,2'-disulfonic acid or compounds of similar
composition which contain a diethanolamino group, a methylamino group,
an anilino group or a 2-methoxyethylamino group instead of the morpholino
group. Brighteners of the substituted diphenyl styryl type, for example
alkali metal salts of 4,4'-bis-(2-sulfostyryl)-diphenyl, 4,4'-bis-(4-chloro-3-
sulfostyryl)-Biphenyl or 4-(4-chlorostyryl)-4'-(2-sulfostyryl)-Biphenyl, may
also be present. Mixtures of the brighteners mentioned above may also be
used. The optical brighteners are used in the detergent tablets according
to the invention in concentrations of 0.01 to 1 % by weight, preferably 0.05
to 0.5% by weight and more preferably 0.1 to 0.25% by weight, based on
the tablet as a whole.
Perfumes are added to the detergent tablets according to the
invention to improve the aesthetic impression created by the products and
to provide the consumer not only with the required washing performance
but also with a visually and sensorially "typical and unmistakable" product.
Suitable perfume oils or perfumes include individual perfume compounds,
for example synthetic products of the ester, ether, aldehyde, ketone,
alcohol and hydrocarbon type. Perfume compounds of the ester type are,
for example, benzyl acetate, phenoxyethyl isobutyrate, p-tert.butyl
cyclohexyl acetate, linalyl acetate, dimethyl benzyl carbinyl acetate, phenyl
ethyl acetate, linalyl benzoate, benzyl formate, ethyl methyl phenyl
glycinate, allyl cyclohexyl propionate, styrallyl propionate and benzyl
salicylate. The ethers include, for example, benzyl ethyl ether; the
aldehydes include, for example, the linear alkanals containing 8 to 18
CA 02307429 2000-OS-03
carbon atoms, citral, citronellal, citronellyloxyacetaldehyde, cyclamen
aldehyde, hydroxycitronellal, lilial and bourgeonal; the ketones include, for
example, the ionones, a-isomethyl ionone and methyl cedryl ketone; the
alcohols include anethol, citronellol, eugenol, geraniol, linalool, phenyl
ethyl
5 alcohol and terpineol and the hydrocarbons include, above all, the
terpenes, such as limonene and pinene. However, mixtures of various
perfumes which together produce an attractive perfume note are preferably
used. Perfume oils such as these may also contain natural perfume
mixtures obtainable from vegetable sources, for example pine, citrus,
10 jasmine, patchouli, rose or ylang-ylang oil. Also suitable are clary oil,
camomile oil, clove oil, melissa oil, mint oil, cinnamon leaf oil, lime
blossom
oil, juniper berry oil, vetiver oil, olibanum oil, galbanum oil and labdanum
oil
and orange blossom oil, neroli oil, orange peel oil and sandalwood oil.
The detergent tablets according to the invention normally contain up
15 to 2% by weight of perfumes, based on the formulation as a whole. The
perfumes may be directly incorporated in the detergents according to the
invention, although it can also be of advantage to apply the perfumes to
supports which strengthen the adherence of the perfume to the washing
and which provide the textiles with a long-lasting fragrance through a
20 slower release of the perfume. Suitable support materials are, for example,
cyclodextrins, the cyclodextrinlperfume complexes optionally being coated
with other auxiliaries.
Suitable enzymes are, in particular, those from the classes of
hydrolases, such as proteases, esterases, lipases or lipolytic enzymes,
25 amylases, cellulases or other glycosyl hydrolases and mixtures thereof. All
these hydrolases contribute to the removal of stains, such as protein-
containing, fat-containing or starch-containing stains, and discoloration in
the washing process. Cellulases and other glycosyl hydrolases can
contribute towards color retention and towards increasing fabric softness by
30 removing pilling and microfibrils. Oxidoreductases may also be used for
CA 02307429 2000-OS-03
46
bleaching and for inhibiting dye transfer. Enzymes obtained from bacterial
strains or fungi, such as Bacillus subtilis, Bacillus licheniformis,
Streptomyces griseus, Coprinus cinereus and Humicola insolens and from
genetically modified variants are particularly suitable. Proteases of the
subtilisin type are preferably used, proteases obtained from Bacillus lentus
being particularly preferred. Of particular interest in this regard are enzyme
mixtures, for example of protease and amylase or protease and lipase or
lipolytic enzymes or protease and cellulase or of cellulase and lipase or
lipolytic enzymes or of protease, amylase and lipase or lipolytic enzymes or
protease, lipase or lipolytic enzymes and cellulase, but especially protease-
and/or lipase-containing mixtures or mixtures with lipolytic enzymes.
Examples of such lipolytic enzymes are the known cutinases. Peroxidases
or oxidases have also been successfully used in some cases. Suitable
amylases include in particular a-amylases, isoamylases, pullanases and
pectinases. Preferred cellulases are cellobiohydrolases, endoglucanases
and ~i-glucosidases, which are also known as cellobiases, and mixtures
thereof. Since the various cellulase types differ in their CMCase and
avicelase activities, the desired activities can be established by mixing the
cellulases in the appropriate ratios.
The enzymes may be adsorbed to supports andlor encapsulated in
membrane materials to protect them against premature decomposition.
The percentage content of the enzymes, enzyme mixtures or enzyme
granules may be, for example, from about 0.1 to 5% by weight and is
preferably from 0.5 to about 4.5% by weight.
In addition, the detergent tablets according to the invention may also
contain components with a positive effect on the removability of oil and fats
from textiles by washing (so-called soil repellents). This effect becomes
particularly clear when a textile which has already been repeatedly washed
with a detergent according to the invention containing this oil- and fat-
dissolving component is soiled. Preferred oil- and fat-dissolving compo-
CA 02307429 2000-OS-03
47
nents include, for example, nonionic cellulose ethers, such as methyl
cellulose and methyl hydroxypropyl cellulose containing 15 to 30% by
weight of methoxyl groups and 1 to 15% by weight of hydroxypropoxyl
groups, based on the nonionic cellulose ether, and the polymers of phthalic
acid andlor terephthalic acid known from the prior art or derivatives thereof,
more particularly polymers of ethylene terephthalates andlor polyethylene
glycol terephthalates or anionically andlor nonionically modified derivatives
thereof. Of these, the sulfonated derivatives of phthalic acid and
terephthalic acid polymers are particularly preferred.
The tablets according to the invention are produced in two steps. In
the first step, detergent tablets are produced in known manner by tabletting
particulate detergent compositions and, in the second step, are provided
with the coating.
Accordingly, the present invention relates to a process for the
production of coated detergent tablets by tabletting a particulate detergent
composition in known manner and then dipping the resulting tablets in or
spraying them with a melt, solution or dispersion of one or more polymers
from the group of
a) water-soluble nonionic polymers from the group of
a1) polyvinyl pyrrolidones,
a2) vinyl pyrrolidonelvinyl ester copolymers,
a3) cellulose ethers
b) water-soluble amphoteric polymers from the group of
b1) alkyl acrylamidelacrylic acid copolymers,
b2) alkyl acrylamide/methacrylic acid copolymers,
b3) alkyl acrylamidelmethyl methacrylic acid copolymers,
b4) alkyl acrylamidelacrylic acidlalkylaminoalkyl (meth)acrylic acid co-
polymers,
CA 02307429 2000-OS-03
48
b5) alkyl acrylamidelmethacrylic acidlalkylaminoalkyl (meth)acrylic acid
copolymers,
b6) alkyl acrylamidelmethyl methacrylic acidlalkylaminoalkyl (meth)-
acrylic acid copolymers,
b7) alkyl acrylamide/alkyl methacrylatelalkylaminoethyl methacrylate/
alkyl methacrylate copolymers,
b8) copolymers of
b8i) unsaturated carboxylic acids,
b8ii) cationically derivatized unsaturated carboxylic acids,
b8iii) optionally other ionic or nonionic monomers,
c) water-soluble zwitterionic polymers from the group of
c1 ) acrylamidoalkyl trialkylammonium chloride/acrylic acid copolymers
and alkali metal and ammonium salts thereof,
c2) acrylamidoalkyl trialkylammonium chloridelmethacrylic acid copoly-
mers and alkali metal and ammonium salts thereof,
c3) methacroyl ethyl betainelmethacrylate copolymers,
d) water-soluble anionic polymers from the group of
d1) vinyl acetate/crotonic acid copolymers,
d2) vinyl pyrrolidone/vinyl acrylate copolymers,
d3) acrylic acid/ethyl acrylatelN-tert.butyl acrylamide terpolymers,
d4) graft polymers of vinyl esters, esters of acrylic acid or methacrylic
acid individually or in admixture copolymerized with crotonic acid,
acrylic acid or methacrylic acid with polyalkylene oxides andlor
polyalkylene glycols,
d5) grafted and crosslinked copolymers from the copolymerization of
d5i) at least one monomer of the nonionic type,
d5ii) at least one monomer of the ionic type,
d5iii) polyethylene glycol and
CA 02307429 2000-OS-03
49
d5iv) a crosslinking agent,
d6) copolymers obtained by copolymerization of at least one monomer
of each of the following three groups:
d6i) esters of unsaturated alcohols and short-chain saturated
carboxylic acids andlor esters of short-chain saturated
alcohols and unsaturated carboxylic acids,
d6ii) unsaturated carboxylic acids,
d6iii) esters of long-chain carboxylic acids and unsaturated
alcohols andlor esters of the carboxylic acids of group d6ii)
with saturated or unsaturated, linear or branched C8_~$
alcohols,
d7) terpolymers of crotonic acid, vinyl acetate and an allyl or methallyl
ester,
d8) tetrapolymers and pentapolymers of
d8i) crotonic acid or allyloxyacetic acid,
d8ii) vinyl acetate or vinyl propionate,
d8iii) branched allyl or methallyl esters,
d8iv) vinyl ethers, vinyl esters or straight-chain allyl or methallyl
esters,
d9) crotonic acid copolymers with one or more monomers from the
group consisting of ethylene, vinyl benzene, vinyl methyl ether,
acrylamide and water-soluble salts thereof,
d10) terpolymers of vinyl acetate, crotonic acid and vinyl esters of a
saturated aliphatic monocarboxylic acid branched in the a-position,
e) water-soluble cationic polymers from the group of
e1) quaternized cellulose derivatives,
e2) polysiloxanes containing quaternary groups,
e3) cationic guar derivatives,
e4) polymeric dimethyl diallylammonium salts and copolymers thereof
CA 02307429 2000-OS-03
with esters and amides of acrylic acid and methacrylic acid,
e5) copolymers of vinyl pyrrolidone with quaternized derivatives of
dialkylaminoacrylate and methacrylate,
e6) vinyl pyrrolidonelmethoimida2olinium chloride copolymers,
5 e7) quaternized polyvinyl alcohol,
e8) polymers known by the INCI names of polyquaternium 2,
polyquaternium 17, polyquaternium 18 and polyquaternium 27.
Analogously to the foregoing observations on the detergent tablets
according to the invention, the polymers mentioned are also preferred for
10 the process according to the invention, so that reference may be made to
the foregoing observations.
The two key process steps are described in the following.
The tablets to be subsequently coated in accordance with the
invention according to the invention are produced by first dry-mixing the
15 ingredients - which may be completely or partly pregranulated - and then
shaping/forming, morre particularly tabletting, the resulting mixture using
conventional processes. To produce the tablets according to the invention,
the premix is compacted between two punches in a die to form a solid
compactate. This process, which is referred to in short hereinafter as
20 tabletting, comprises four phases, namely metering, compacting (elastic
deformation), plastic deformation and ejection.
The premix is first introduced into the die, the filling level and hence
the weight and shape of the tablet formed being determined by the position
of the lower punch and the shape of the die. Uniform dosing, even at high
25 tablet throughputs, is preferably achieved by volumetric dosing of the
premix. As the tabletting process continues, the top punch comes into
contact with the premix and continues descending towards the bottom
punch. During this compaction phase, the particles of the premix are
pressed closer together, the void volume in the filling between the punches
30 continuously diminishing. The plastic deformation phase in which the
CA 02307429 2000-OS-03
51
particles coalesce and form the tablet begins from a certain position of the
top punch (and hence from a certain pressure on the premix). Depending
on the physical properties of the premix, its constituent particles are also
partly crushed, the premix sintering at even higher pressures. As the
tabletting rate increases, i.e. at high throughputs, the elastic deformation
phase becomes increasingly shorter so that the tablets formed can have
more or less large voids. In the final step of the tabletting process, the
tablet is forced from the die by the bottom punch and carried away by
following conveyors. At this stage, only the weight of the tablet is
definitively established because the tablets can still change shape and size
as a result of physical processes (re-elongation, crystallographic effects,
cooling, etc.).
The tabletting process is carried out in commercially available tablet
presses which, in principle, may be equipped with single or double
punches. In the latter case, not only is the top punch used to build up
pressure, the bottom punch also moves towards the top punch during the
tabletting process while the top punch presses downwards. For small
production volumes, it is preferred to use eccentric tablet presses in which
the punches) is/are fixed to an eccentric disc which, in turn, is mounted on
a shaft rotating at a certain speed. The movement of these punches is
comparable with the operation of a conventional four-stroke engine.
Tabletting can be carried out with a top punch and a bottom punch,
although several punches can also be fixed to a single eccentric disc, in
which case the number of die bores is correspondingly increased. The
throughputs of eccentric presses vary according to type from a few hundred
to at most 3,000 tablets per hour.
For larger throughputs, rotary tablet presses are generally used. In
rotary tablet presses, a relatively large number of dies is arranged in a
circle on a so-called die table. The number of dies varies - according to
model - between 6 and 55, although even larger dies are commercially
CA 02307429 2000-OS-03
52
available. Top and bottom punches are associated with each die on the
die table, the tabletting pressures again being actively built up not only by
the top punch or bottom punch, but also by both punches. The die table
and the punches move about a common vertical axis, the punches being
brought into the filling, compaction, plastic deformation and ejection
positions by means of curved guide rails. At those places where the
punches have to be raised or lowered to a particularly significant extent
(filling, compaction, ejection), these curved guide rails are supported by
additional push-down members, pull-down rails and ejection paths. The die
is filled from a rigidly arranged feed unit, the so-called filling shoe, which
is
connected to a storage container for the premix. The pressure applied to
the premix can be individually adjusted through the tools for the top and
bottom punches, pressure being built up by the rolling of the punch shank
heads past adjustable pressure rollers.
To increase throughput, rotary presses can also be equipped with
two filling shoes so that only half a circle has to be negotiated to produce a
tablet. To produce two-layer or multiple-layer tablets, several filling shoes
are arranged one behind the other without the lightly compacted first layer
being ejected before further filling. Given suitable process control, shell
and bull's-eye tablets - which have a structure resembling an onion skin -
can also be produced in this way. In the case of bull's-eye tablets, the
upper surface of the core or rather the core layers is not covered and thus
remains visible. Rotary tablet presses can also be equipped with single or
multiple punches so that, for example, an outer circle with 50 bores and an
inner circle with 35 bores can be simultaneously used for tabletting.
Modern rotary tablet presses have throughputs of more than one million
tablets per hour.
Where rotary presses are used for tabletting, it has proved to be of
advantage to carry out the tabletting process with minimal variations in the
weight of the tablets. Variations in tablet hardness can also be reduced in
CA 02307429 2000-OS-03
53
this way. Minimal variations in weight can be achieved as follows:
- using plastic inserts with minimal thickness tolerances
- low rotor speed
- large filling shoe
- adapting the rotational speed of the filling shoe blade to the rotor speed
- filling shoe with constant powder height
- decoupling the filling shoe from the powder supply
Any of the nonstick coatings known in the art may be used to reduce
caking on the punch. Plastic coatings, plastic inserts or plastic punches are
particularly advantageous. Rotating punches have also proved to be of
advantage; if possible, the upper and lower punches should be designed
for rotation. If rotating punches are used, there will generally be no need
for a plastic insert. In that case, the surfaces of the punch should be
electropolished.
It has also been found that long tabletting times are advantageous.
These can be achieved by using pressure rails, several pressure rollers or
low rotor speeds. Since variations in tablet hardness are caused by
variations in the pressures applied, systems which limit the tabletting
pressure should be used. Elastic punches, pneumatic compensators or
spring elements in the force path may be used. The pressure roller can
also be spring-mounted.
Tabletting machines suitable for the purposes of the invention can
be obtained, for example, from the following companies: Apparatebau
Holzwarth GbR, Asperg; Wilhelm Fette GmbH, Schwarzenbek; Hofer
GmbH, Weil; Horn & Noack Pharmatechnik GmbH, Worms; IMA
Verpackungssysteme GmbH Viersen; KILIAN, Cologne; KOMAGE, Kell am
See, KORSCH Pressen GmbH, Berlin; and Romaco GmbH, Worms. Other
suppliers are, for example Dr. Herbert Pete, Vienna (AU); Mapag
Maschinenbau AG, Bern (Switzerland); BWI Manesty, Liverpool (GB); I.
Holand Ltd., Nottingham (GB); and Courtoy N.V., Halle (BE/LU) and
CA 02307429 2000-OS-03
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Medicopharm, Kamnik (SI). One example of a particularly suitable
tabletting machine is the model HPF 630 hydraulic double-pressure press
manufactured by LAEIS, D. Tabletting tools are obtainable, for example,
from Adams Tablettierwerkzeuge Dresden; Wilhelm Fett GmbH,
Schwarzenbek; Klaus Hammer, Solingen; Herber & Sohne GmbH,
Hamburg; Hofer GmbH, Weil; Horn & Noack, Pharmatechnik GmbH,
Worms; Ritter Pharmatechnik GmbH, Hamburg; Romaco GmbH, Worms
and Notter Werkzeugbau, Tamm. Other suppliers are, for example, Senss
AG, Reinach (CH) and Medicopharm, Kamnik (SI).
The tablets can be made in certain shapes and certain sizes.
Suitable shapes are virtually any easy-to-handle shapes, for example
slabs, bars, cubes, squares and corresponding shapes with flat sides and,
in particular, cylindrical forms of circular or oval cross-section. This last
embodiment encompasses shapes from tablets to compact cylinders with a
height-to-diameter ratio of more than 1.
The portioned pressings may be formed as separate individual
elements which correspond to a predetermined dose of the detergent.
However, it is also possible to form pressings which combine several such
units in a single pressing, smaller portioned units being easy to break off in
particular through the provision of predetermined weak spots. For the use
of laundry detergents in machines of the standard European type with
horizontally arranged mechanics, it can be of advantage to produce the
portioned pressings as cylindrical or square tablets, preferably with a
diameter-to-height ratio of about 0.5:2 to 2:0.5. Commercially available
hydraulic presses, eccentric presses and rotary presses are particularly
suitable for the production of pressings such as these.
The three-dimensional form of another embodiment of the tablets
according to the invention is adapted in its dimensions to the dispensing
compartment of commercially available domestic washing machines, so
that the tablets can be introduced directly, i.e. without a dosing aid, into
the
CA 02307429 2000-OS-03
- 55
dispensing compartment where they dissolve on contact with water.
However, it is of course readily possible - and preferred in accordance with
the present invention - to use the detergent tablets in conjunction with a
dosing aid.
Another preferred tablet which can be produced has a plate-like or
slab-like structure with alternately thick long segments and thin short
segments, so that individual segments can be broken off from this "bar" at
the predetermined weak spots, which the short thin segments represent,
and introduced into the machine. This "bar" principle can also be
embodied in other geometric forms, for example vertical triangles which are
only joined to one another at one of their longitudinal sides.
In another possible embodiment, however, the various components
are not compressed to form a single tablet, instead the tablets obtained
comprise several layers, i.e. at least two layers. These various layers may
have different dissolving rates. This can provide the tablets with favorable
performance properties. If, for example, the tablets contain components
which adversely affect one another, one component may be integrated in
the more quickly dissolving layer while the other component may be
incorporated in a more slowly dissolving layer so that the first component
can already have reacted off by the time the second component dissolves.
The various layers of the tablets can be arranged in the form of a stack, in
which case the inner layers) dissolve at the edges of the tablet before the
outer layers have completely dissolved. Alternatively, however, the inner
layers) may also be completely surrounded by the layers lying further to
the outside which prevents constituents of the inner layers) from dissolving
prematurely.
In another preferred embodiment of the invention, a tablet consists
of at least three layers, i.e. two outer layers and at least one inner layer,
a
peroxy bleaching agent being present in at least one of the inner layers
whereas, in the case of the stack-like tablet, the two cover layers and, in
CA 02307429 2000-OS-03
56
the case of the envelope-like tablet, the outermost layers are free from
peroxy bleaching agent. In another possible embodiment, peroxy
bleaching agent and any bleach activators or bleach catalysts present
and/or enzymes may be spatially separated from one another in one and
the same tablet. Multilayer tablets such as these have the advantage that
they can be used not only via a dispensing compartment or via a dosing
unit which is added to the wash liquor, instead it is also possible in cases
such as these to introduce the tablet into the machine in direct contact with
the fabrics without any danger of spotting by bleaching agent or the like.
Besides the layered structure, multiphase tablets may also be
produced in the form of ring/core tablets, coreljacket tablets or so-called
bull's-eye tablets. An overview of these various forms of multiphase tablets
can be found in EP 055 100 (Jeyes Group). This document discloses
lavatory cleaning blocks comprising a shaped body of a slowly dissolving
cleaning composition in which a bleach tablet is embedded. At the same
time, it discloses various forms of multiphase tablets from the simple
multiphase tablet to complicated multilayer systems with inserts.
After pressing, the detergent tablets have high stability. The fracture
resistance of cylindrical tablets can be determined via the diametral fracture
stress. This in turn can be determined in accordance with the following
equation:
a-
2P
~Dt
where a represents the diametral fracture stress (DFS) in Pa, P is the force
in N which leads to the pressure applied to the tablet that results in
fracture
thereof, D is the diameter of the tablet in meters and t is its height.
Preferred processes for the production of detergent tablets start out
from surfactant-containing granules which are compounded with other
ingredients to form a tablettable particulate premix. Analogously to the
CA 02307429 2000-OS-03
57
foregoing observations on preferred ingredients of the detergent tablets
according to the invention, the use of other ingredients may also be applied
to their production. In preferred processes, the particulate premix
additionally contains surfactant-containing granules and has a bulk density
of at least 500 gll, preferably at least 600 gll and more preferably at least
700 gll.
In preferred processes according to the invention, the surfactant-
containing granules have particle sizes between 100 and 2000 Nm,
preferably between 200 and 1800 Nm, more preferably between 400 and
1600 Nm and most preferably between 600 and 1400 Nm.
The other ingredients of the detergent tablets according to the
invention may also be introduced into the process according to the
invention, for which purpose reference is made to the foregoing
observations. Preferred processes are characterized in that the particulate
premix additionally contains one or more substances from the group of
bleaching agents, bleach activators, disintegration aids, enzymes, pH
regulators, perfumes, perfume carriers, fluorescers, dyes, foam inhibitors,
silicone oils, redeposition inhibitors, optical brighteners, discoloration
inhibitors, dye transfer inhibitors and corrosion inhibitors.
The second step of the process according to the invention
comprises applying the coating. This may be done by conventional coating
techniques, i.e. in particular dipping the tablet in or spraying the tablet
with
a melt, solution or dispersion of the polymers mentioned.
Since the dipping of detergent tablets into melts or solutions or
dispersions only leads to the thin coatings required with considerable
outlay on the necessary equipment, it is preferred in accordance with the
present invention to spray polymer solutions or dispersions onto the tablets,
the solvent or dispersant evaporating and leaving a coating behind on the
tablet. In preferred processes according to the invention, an aqueous
solution of one or more polymers from groups a) to e) is sprayed onto the
CA 02307429 2000-OS-03
58
tablets, the aqueous solution containing - based on the solution - 1 to 20%
by weight, preferably 2 to 15% by weight and more preferably 4 to 10% by
weight of polymers) from groups a) to e), optionally up to 20% by weight,
preferably up to 10% by weight and more preferably less than 5% by
weight of one or more water-miscible solvents and - for the rest - water.
In order to shorten the drying time, other water-miscible readily
volatile solvents may be added to and mixed with the aqueous solution.
These solvents belong in particular to the group of alcohols, ethanol, n-
propanol and isopropanol being preferred. For reasons of cost, ethanol
and isopropanol are particularly appropriate.
The polymers from groups a) to e) make up 50 to 100% by weight of
the coating of the tablets according to the invention. Accordingly, the
solution to be sprayed onto the tablets may contain other ingredients, an
addition of polyurethanes - as mentioned above - being preferred. If water-
insoluble polyurethanes are added, the liquid to be sprayed on is a
dispersion.
Accordingly, another preferred embodiment of the process according
to the invention is a variant in which an aqueous dispersion of one or more
polyurethanes additionally containing one or more dissolved polymers from
groups a) to e) is sprayed onto the tablets, the dispersion containing -
based on the dispersion - 1 to 20% by weight, preferably 2 to 15% by
weight and more preferably 4 to 10% by weight of polyurethane(s), 1 to
20% by weight, preferably 2 to 15% by weight and more preferably 4 to
10% by weight of polymers) from groups a) to e), optionally up to 20% by
weight, preferably up to 10% by weight and more preferably below 5% by
weight of one or more water-miscible solvents and - for the rest - water.
Aqueous dispersions in the context of the present invention are
dispersions of which the outer phase consists predominantly of water. The
outer phase may additionally contain other water-miscible solvents such as,
for example, ethanol and isopropanol. These other solvents are present in
CA 02307429 2000-OS-03
59
quantities of at most up to 20% by weight, based on the dispersion as a
whole. The outer phase preferably contains water as sole solvent. Another
preferred embodiment contains no more than 5%, based on the dispersion
as a whole, of other solvents in the outer phase.
The spraying of aqueous solutions or dispersions of the type in
question can be carried out in various ways familiar to the expert. For
example, the solution or dispersion may be delivered by means of a pump
system to a nozzle where the solution or dispersion is finely atomized
under the effect of the powerful shear forces. The spray mist formed can
then be directed onto the tablets to be coated which are then optionally
dried by suitable measures (for example by blowing heated air onto them).
However, it is also possible to use a multicomponent nozzle and to spray
the aqueous solutions or dispersions by means of a gas stream through the
nozzle. In the most simple case, a two-component nozzle is used with
compressed air as the carrier gas. In order to protect the dispersion
against oxidation or other interactions with the carrier gas, other carrier
gases, for example nitrogen noble gases, lower alkanes or ethers, may
also be used.
The water content of the dispersion or solution may also be reduced
which shortens the drying times, minimizes interactions with moisture-
sensitive ingredients on the tablet surface and reduces production costs.
Here, too, the lower alcohols mentioned above represent suitable solvents,
solvent mixtures completely free from water being less preferred because
certain quantities of water promote the formation of a uniform coating. In
preferred processes according to the invention, a solution or dispersion of
one or more polymers from groups a) to e) in a solvent or solvent mixture
from the group consisting of water, ethanol, propanol, isopropanol, n-
heptane and mixtures thereof is sprayed onto the tablets using inert
propellents from the group consisting of nitrogen, dinitrogen oxide,
propane, butane, dimethyl ether and mixtures thereof.
CA 02307429 2000-OS-03
In preferred process variants such as these, the solutions or
dispersions advantageously have the following composition (the quantities
being based on the dispersion to be sprayed on):
i) 30 to 99% by weight, preferably 40 to 90% by weight and more
5 preferably 50 to 85% by weight of ethanol, propanol, isopropanol, n
heptane or mixtures thereof,
ii) 0 to 20% by weight, preferably 1 to 15% by weight and more preferably
2 to 10% by weight of water,
iii) 1 to 50% by weight, preferably 2 to 25% by weight and more preferably
10 3 to 10% by weight of one or more polymers from groups a) to e).
If polyurethanes or other ingredients are to be part of the coating,
they may replace up to 50% by weight, based on the weight mentioned, of
the polymers from groups a) to e) in the general formulation mentioned
above.
15 Other ingredients of the dispersions to be sprayed on may be, for
example, dyes or perfumes or pigments. Additives such as these improve,
for example, the visual or olfactory impression of the tablets coated in
accordance with the invention. Dyes and perfumes are described in detail
in the foregoing. Suitable pigments are, for example, white pigments, such
20 as titanium dioxide or zinc sulfide, pearlescent pigments or colored
pigments. Colored pigments may be divided into inorganic and organic
pigments. If they are used, the pigments mentioned are all preferably
used in fine-particle form, i.e. with mean particle sizes of 100 pm or far
smaller.
25 In order to obtain a thin, uniform coating, the solution or dispersion
of the coating materials is preferably converted into a fine mist before it
impinges on the tablets. Preferred processes according to the invention
are characterized in that the particular solution andlor dispersion is applied
to the tablets through a nozzle, the mean droplet size in the spray mist
30 being less than 100 Nm, preferably less than 50 Nm and more preferably
CA 02307429 2000-OS-03
61
less than 35 Nm. The preferred coating thickness mentioned above can
readily be achieved in this way.
The present invention also relates to-the use of polymers or polymer
mixtures for coating detergent tablets, the polymer or at least 50% by
weight of the polymer mixture being selected from
a) water-soluble nonionic polymers from the group of
a1) polyvinyl pyrrolidones,
a2) vinyl pyrrolidonelvinyl ester copolymers,
a3) cellulose ethers
b) water-soluble amphoteric polymers from the group of
b1) alkyl acrylamide/acrylic acid copolymers,
b2) alkyl acrylamidelmethacrylic acid copolymers,
b3) alkyl acrylamidelmethyl methacrylic acid copolymers,
b4) alkyl acrylamidelacrylic acid/alkylaminoalkyl (meth)acrylic acid co-
polymers,
b5) alkyl acrylamidelmethacrylic acidlalkylaminoalkyl (meth)acrylic acid
copolymers,
b6) alkyl acrylamidelmethyl methacrylic acidlalkylaminoalkyl (meth)-
acrylic acid copolymers,
b7) alkyl acrylamide/alkyl methacrylate/alkylaminoethyl methacrylatel
alkyl methacrylate copolymers,
b8) copolymers of
b8i) unsaturated carboxylic acids,
b8ii) cationically derivatized unsaturated carboxylic acids,
b8iii) optionally other ionic or nonionic monomers,
c) water-soluble zwitterionic polymers from the group of
c1) acrylamidoalkyl trialkylammonium chloridelacrylic acid copolymers
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62
and alkali metal and ammonium salts thereof,
c2) acrylamidoalkyl trialkylammonium chloridelmethacrylic acid copoly-
mers and alkali metal and ammonium salts thereof,
c3) methacroyl ethyl betainelmethacrylate copolymers,
d) water-soluble anionic polymers from the group of
d1) vinyl acetatelcrotonicacid copolymers,
d2) vinyl pyrrolidonelvinyl acrylate copolymers,
d3) acrylic acidlethyl acrylatelN-tert.butyl acrylamide terpolymers,
d4) graft polymers of vinyl esters, esters of acrylic acid or methacrylic
acid individually or in admixture copolymerized with crotonic acid,
acrylic acid or methacrylic acid with polyalkylene oxides andlor
polyalkylene glycols,
d5) grafted and crosslinked copolymers from the copolymerization of
d5i) at least one monomer of the nonionic type,
d5ii) at least one monomer of the ionic type,
d5iii) polyethylene glycol and
d5iv) a crosslinking agent,
d6) copolymers obtained by copolymerization of at least one monomer
of each of the following three groups:
d6i) esters of unsaturated alcohols and short-chain saturated
carboxylic acids andlor esters of short-chain saturated
alcohols and unsaturated carboxylic acids,
d6ii) unsaturated carboxylic acids,
d6iii) esters of long-chain carboxylic acids and unsaturated
alcohols and/or esters of the carboxylic acids of group d6ii)
with saturated or unsaturated, linear or branched Ca-~e
alcohols,
d7) terpolymers of crotonic acid, vinyl acetate and an allyl or methallyl
ester,
CA 02307429 2000-OS-03
63
d8) tetrapolymers and pentapolymers of
d8i) crotonic acid or allyloxyacetic acid,
d8ii) vinyl acetate or vinyl propionate,
d8iii) branched allyl or methallyl esters,
d8iv) vinyl ethers, vinyl esters or straight-chain allyl or methallyl
este rs,
d9) crotonic acid copolymers with one or more monomers from the
group consisting of ethylene, vinyl benzene, vinyl methyl ether,
acrylamide and water-soluble salts thereof,
d10) terpolymers of vinyl acetate, crotonic acid and vinyl esters of a
saturated aliphatic monocarboxylic acid branched in the a-position,
e) water-soluble cationic polymers from the group of
e1) quaternized cellulose derivatives,
e2) polysiloxanes containing quaternary groups,
e3) cationic guar derivatives,
e4) polymeric dimethyl diallylammonium salts and copolymers thereof
with esters and amides of acrylic acid and methacrylic acid,
e5) copolymers of vinyl pyrrolidone with quaternized derivatives of
dialkylaminoacrylate and methacrylate,
e6) vinyl pyrrolidonelmethoimidazolinium chloride copolymers,
e7) quaternized polyvinyl alcohol,
e8) polymers known by the INCI names of polyquaternium 2,
polyquaternium 17, polyquaternium 18 and polyquaternium 27.
This use of the above-mentioned polymers in accordance with the
invention leads to coated tablets with advantageous properties, as the
following non-limiting Examples show. The foregoing observations on the
process according to the invention apply equally to preferred embodiments
of the use according to the invention (ingredients, composition of the
CA 02307429 2000-OS-03
64
premix, preferred polymers, etc.).
Examples
To produce uncoated detergent tablets, surfactant granules were
mixed with other ingredients and tabletted in an eccentric tablet press. The
composition of the surfactant granules is shown in Table 1 below while the
composition of the premix to be tabletted (and hence the composition of the
tablets) is shown in Table 2.
Table 1:
Surfactant granules [% by weight]
Cs-~3 alkyl benzenesulfonate 18.4
C~2_~$ fatty alcohol sulfate 4.9
C~2_~g fatty alcohol ~ 7 EO 4.9
Soap 1.6
Sodium carbonate 18.8
Sodium silicate 5.5
Zeolite A (water-free active substance)31.3
Optical brightener 0.3
Na hydroxyethane-1,1-diphosphonate0.8
Acrylic acidlmaleic acid copolymer5.5
Water, salts Balance
CA 02307429 2000-OS-03
Table 2:
Premix [% by weight]
Surfactant granules 62.95
Sodium perborate monohydrate17.00
Tetraacetyl ethylenediamine 7.30
Foam inhibitor 3.50
Enzymes 1.70
Repel-O-Tex~ SRP 4* 1.10
Perfume 0.45
Zeolite A 1.00
Cellulose 5.00
** Terephthalic acid/ethylene glycollpolyethylene glycol ester (Rhodia,
Rhone-Poulenc)
The tablettable premix was tabletted in a Korsch eccentric press
(tablet diameter 44 mm, tablet height 22 mm, tablet weight 37.5 g).
The resulting tablets were divided up into three series, of which the
first series was used untreated as Comparison Example C while the
second series E1 was sprayed with a 20% by weight solution of a polyvinyl
pyrrolidonelpolyvinyl acetate copolymer in ethanol/water. The third series
E2 was sprayed with a solution of polyvinyl pyrrolidone/vinyl alcohol
copolymer and butyl aminoethyl methacrylate in waterlisopropanol. In both
cases E1 and E2, dimethyl ether was used as the propellent for the
dispersions which were atomized to a droplet size of 30 Nm. In the case of
Example E1, 150 mg of the polymer was applied as the coating
corresponding to a ratio of uncoated tablet to coating of 250:1. In Example
E2 according to the invention, 100 mg of polymer were applied
(corresponding to a ratio of uncoated tablet to coating of 375:1) and the
test was repeated with only 50 mg of polymer (E2', corresponding to a ratio
CA 02307429 2000-OS-03
66
of uncoated tablet to coating of 750:1 ).
Two tablets from each of the three series C, E1 and E2 were placed
on a 4 mm mesh sieve and shaken for 120 seconds at maximum amplitude
on a Retsch sieving machine. After this test, the weight loss of the tablets
was determined. Table 3 below shows the weight loss of tablets E1, E2
and C, the values representing the average values of five determinations.
To determine tablet disintegration, a tablet was placed in a glass
beaker filled with water (600 ml water, temperature 30°C) and the time
taken for the tablet to disintegrate completely was measured. The
experimental data of the individual tablet series are shown in Table 3:
Table 3:
Detergent tablets [physical data]
Tablet E1 E2 E2' V
Weight loss [% by weight]3.36 4.0 4.3 6.7
Tablet disintegration 15 14 13 13
[s]
The results show that abrasion can be distinctly reduced, even with
extremely small amounts of coating material, without any effect on the
disintegration time.
