Note: Descriptions are shown in the official language in which they were submitted.
IMPROVED POLYMER SHEET FOR DELIVERING
LA
PRODUCT FORMED FROM SAME
BACKGROUND OF THE INVE~TION
1. ield of the Invention
.
This invention relates to a polymeric sheet or carrier capable
of storing and delivering to a wash, corrosive laundry care
additives. In particular, it relateS to a Storage~stable
sheet for packaging laundry care additives which is soluble in
aqueous and detergent solutions.
It has long been desired to provide a single vehicle adapted
to permit prepackaging of desired amounts of laundry care
additives and for delivering such additives to a washing
machine or other laundry water by simply adding a package
formed from that vehicle to the wash. Typical washing machine
additives include corrosive bleaches, enzymes, fabric
softeners, fabric conditioners, wrinkle-release additives,
additives for imparting a specific feel or "hand" to fabrics
and detergents. Since many of such additives are not
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3~749
compa-tible with the skin and become de~raded durirlg storage
without suitable protection, there has been a continuing
problem for storing such a~ditives and for delivering them
to a washing machine or the like.
It has been proposed to employ packages comprising water
soluble bags containing deteryents for laundry use. Such bags
are particularly appealing for home use w~ere a measured
amount of laundry care additive, such as a bleach or
detergent, may be added directly into a laundering machine
without waste or rness. Such packages are intended to peovide
the required amount of laundry care additive for a single
filling of that machine.
Until now, however, such packages or other delivery systems
have not pLoved entirely satisfactory. rrhe difficulties in
fabricating satisfactory packages have frustrated the art for
many years. Sheet material for carrying a laundry care
additive must simultaneously satisfy many conflicting
requirements. The material must form a self-supporting film
which rapidly dissolves or disperses in wash water at
temperatures typically from about 60F to 140F.
.
It has been proposed, for example, in U.S. Patent 3,322,674 to
employ polymeric materials having water~solubilizing groups or
hydrophilic groups for that purpose. Such dissolvable film
forming materials, as poly (vinyl alcohol) or cellulosic
derivatives, however, were found to be oxidized by and
rendered insoluble by strong laundry care additives, SUCtl as
chlorine bleaches. Accordingly, it has been proposed to
employ a barrier coating on the inside surface of the laundry
package to shield the packaging material from the chlorine
bleach. However, such packets have not been satisfactory,
since upon prolonged storage, the barrier coatings tend to
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crac]; or tear and permit the bleach to contact the
packag ng material. After prolonged contact, the
packaging material is oxidized and becomes water
insoluble and the chlorine bleach loses its activity.
Conventional solution polymers providing high water
solubility and containing from 25-50% of alkali-soluble
monomers were once thought to be unsuitable as laundry
care packaging material. Films formed from such poly-
mers are ususally hygroscopic and, during storage at
high relative humidity, tend to lose dimensional stability
and become unduly tacky. In addition, at low temperatures
and low relative humidity often encounterea during
storage, such films tend to become unduly brittle.
Accordingly, rolls of tear off packages formed from such
sheet material may not readily separate by tearing.
Further, conventional water-soluble polymers often lose
their flexibility, during storage at low temperatures of
~ -17.7C (0F) or lower. The present invention overcomes
these difficulties and remains relatively stable during
these conditions.
Other water soluble, film forming material, such as
cellulosic materials, are not easily cast into sheets
1 and are not readily heat sealable. Accordingly, it
can be difficult and time consuming to economically
utilize such materials.
The ob~ect of this invention is to provide a polymeric
carrier in sheet form capable of retaining a pre-selected
amount of reactive laundry care additive, which carrier
is inert and stable to said additive during storage.
The present invention provides a water soluble sheet
for delivering laundry additives which is characterized
by a self ~upporting film of an addition polymer formed
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of:
(a~ from about 0 to 85% by weight of a water-
insoluble soft monomer;
(b) from about 15 to 100% by weight of a water-
soluble anionic monomer;
(c) from about 0 to 25% by weight of a water-
soluble nonionic monomer; and
(d) from about 0 to 40% by weight of a water-
insoluble hard monomer;
wherein said addition polymer is up to about 100%
neutralized with a Group IA metal base or a Group IA
metal basic salt.
The water-soluble sheet of this invention will dissolve
or di~sperse readily in aqueous or detergent solutions
at temperatures from about 15.5C to about 60C (about
60 F to about 1400F).
The sheet possesses sufficient strength to resist the
rigors of mechanical packaging processes, but which
retains sufficient fl~exibility to permit handling with-
out premature rupture or disintegrationO The sheet
also resists the destabilizing effects of high humidity. -
Further, the sheet resists embrittlement at low relative
humidity or at low temperatures.
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The addition polymer is neutralized to up to 100~ of
theoretical employing a Group IA me-tal base or a Group IA
metal basic salt when anionic monomer is present in amounts
of 15 to 100%. The polymer has a molecular weight of at
least 25,000, preferably over 50,000, and most preferably
over 100,000.
It has been found that such acrylic polymers possess unusual
stability towards reactive laundry care additives, including
particulate chlorine bleaches. Such polymers also possess
sufficient mechanical strength to be formulated into sheets
for laundry care products and can be formulated to maintain
their integrity over a broad range of temperature and humidity.
The polymers of the invention are readily prepared by
conventional free-radical polymerization. Sheets formed from
acrylic polymers are readily heat sealed to provide storage
stable products. In addition, the polymer sheet is not
substantive to conventional fibers and is inert to
conventional laundry additives.
A laundry care product is provided which may have a
particulate laundry care additive carried within the sheet of
the invention or the laundry care product may be a multitude
of small wafers distributed within the shee~. In one aspect
the product is a uniformly dispersed particulate layer of
laundry care additive contained within a unit formed by the
sheet of the invention and in others, it assumes the wafers
within the sheets. The product is produced, for example, by
forming a unit including a dispersed layer of laundry care
additive and at least one sheet oE the invention and then
sealing the unit.
Since the sheet form of the laundry care product contains the
bleach as physically separated particles, or wafers, this
invention offers the following advantages over water-soluble
bags:
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~1) cl~mping oE the active ingredient is not possible;
~2) there can be more controlled metering of the dissolving
bleach;
~3) spot damage to the fabrics is minimized.
.
DETAILED ~ESCRIPTION OF THE INVENTION
The addition polymers of the invention utilize a soft,
water-insoluble monomer. Suitable polymerizable monomers
which form soft, water-insoluble polymers in the presence of
free-radical catalysts include primary and secondary alkyl
acrylates, having alkyl substituents with up to 18 or more
carbon atoms; primary or secondary alkyl methacrylates having
alkyl substituents o 5 to 18 or more carbon atoms or other
ethylenically-unsaturated compounds ~7hich are polymerizable
with free-radical catalysts to form soft, solid polymers.
Other typical soft monomers of the invention include: vinyl
esters of saturated monocarboxylic acids, olefin monomers,
such as ethylene and propylene, and conjugated dienes forming
rubbery latices such as butadiene, chloroprene, isobutene and
isoprene.
The preferred soft monomers include alkyl acrylates in which
the alkyl group has from 1 to 8 carbon atoms and alkyl
methacrylates wherein the alkyl group has from 5 to 18 carbon
atoms. Examples of such compounds include: amyl acrylate;
2-ethylhexyl acrylate octyl acrylate; n-amyl methacrylate;
hexyl methacrylate; octyl methacrylate; dodecyl methacrylate
and those acrylates or methacrylates with substituted alkyl
groups, such as butoxyethyl acrylate or methacrylate.
Best results are obtained, and accordingly, it is especially
preferred to employ alkyl acrylates in which the alkyl group
--6--
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has from 1 to 4 carbon atoms. Typical compounds include:
methyl acrylate, et:hyl acrylate, propyl acrylate and butyl
acrylate, and preferably bu-tyl acrylate.
The water-soluble anionic monomer which is combined with
the water-insoluble soft monomer to form an addition
polymer of the invention includes monomers having wat0r or
alkali-solubilizing anionic functionalities including
carboxyl groups, sulfonic acid groups, sulfate groups,
phosphate groups and the like. If desired, monomeric
precursors such as acrylamides, maleic anhydride, acrylic
esters, acrylonitrile and the like can be employed in th~
addition reaction under conditions where they form
ionizable groups, such as carboxyl groups, in the
copolymer.
Monomers containing carboxylic acid are preferred
including: maleic acid; fumaric acid; beta-carboxy-
ethylacrylate; itaconic acid and the like. Best results
are obtained and, accordingly, it is preferred to employ as
the anionic monomer, methacrylic acid or acrylic acid.
A preferred addition polymer includes an acrylic copolymer
formed from a water-insoluble soft monomer such as methyl
acxylate, ethyl acrylate, or butyl acrylate and an anionic
monomer selected from methacrylic acid, acrylic acid or
maleic acid.
The water-soluble nonionic monomer of the invention is
employed, when desired, to enhance the dissolvability of
the polymer and to permit a reduction in the amount of
anionic functionality present in the polymer. Accordingly,
monomers for providing enhanced water solubility, but free
from ionizable functionalities, include hydroxyalkyl
acrylates and methacrylates containing an alkylene group
having from 2 to 6 carbon atoms to which the hydroxy group
is attached. Examples of such monomers includQ 2-
hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and,
- 7 -
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more preferably, 2-hydroxyethyl acrylate and 2-hydroxy
ethyl methacrylate. O-ther water-soluble nonionic monomers
include N-vinylpyrrolidone, vinyl acetate (hydrolyzed), 3-
chloro-2-hydroxypropyl acrylate, 6-hydroxyhexyl acrylate,
5,6-dihydroxyhexyl ~ethacryla-te and the like.
Addition polymers of the invention incorporating a nonionic
monomer include, for example, ethyl acrylate/hydroxyethyl
methacrylate/methacrylic acid; methyl acrylate/hydroxyethyl
acrylate/methacrylic acid; butyl acrylate/hydroxypropyl
methacrylate/methacrylic acid; ethyl acrylate/N-vinyl
pyrrolidone/methacrylic acid; butadiene/hydroxyethyl
methacrylate/methacrylic acid and methyl
acrylate/acrylamide/maleic acid.
Preerred polymers of the invention containing nonionic
monomers include: ethyl acrylate/hydroxyethyl
methacrylate/methacrylic acid; e~hyl acrylate/hydroxyethyl
acrylate/methacrylic acid; ethyl acrylate/hydroxyethyl
acrylate/acrylic acid; ethyl acrylate/hydroxyethyl
methacrylate/acrylic acid and ethyl
acrylate/acrylamide/methacrylic acid.
In order to reduce the tendency to develop tack at high
relative humidity, it may be desirable to include a minor
amount of a water-insoluble hard monomer in the addition
polymer of the invention. Water-insoluble hard monomers of
the invention include polymerizable ethylenically
unsaturated monomers including: benzyl acrylate or
methacrylate, vinyl chloride, chlorostyrene, vinyl acetate
and alpha-methylstryene. A preferred class of water-
insoluble hard monomers includes: acrylonitrile;
methacrylonitirle and styrene.
Enhanced results have been obtained, and accordingly, it is
preferred to employ as the hard monomer, a C1 to C4 alkyl
methacrylate. Typical examples of such monomers include
ethyl methacrylate, propyl methacrylate, isopropyl
-- 8 --
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methacrylate, n-butyl methacrylate and sec-butyl
methacrylate. An especially preferred hard monomer is
methyl methacrylate.
Examples of preferred polymers of the invention containing
such hard monomers include: butyl acrylate/methyl
methacrylate/methacrylic acid; ethyl
acrylate/methylmethacrylate/methacrylic acid and methyl
acrylate/methyl methacrylate/acrylic acid.
In order to impart sufficient water solubility to the
polymer, the degree of neutralization of the anionic groups
with a cation such as ammonium or a Group IA metal cation
employed as a base or a basic salt will vary depending on
the proportion of anionic monomer used in the polymer. The
metal cation may be sodium, potassium, lithium or the like;
the base may be a hydroxide and the basic salt a
bicarbonate, a carbonate or the like. Polymers with a high
proportion of anionic monomer may require only a low degree
of neutralization and, conversely, polymers with a low
proportion of anionic monomer may require a high degree of
neutralization and it is possible to have 0 to 100%
neutralization of the anionic monomer. Moreover, it is not
necessary to over-neutralize the anionic monomer.
It may be possible to employ other metal cations in the
neutralizing compound. Group II metal cations have been
found to be somewhat less effective than the Group IA metal
cations in providing water and detergent solution
solubility for the polymer.
The proportions of monomers employed in the polymer sheet
of the invention should be sufficient to provide balanced
properties of rapid water solubility and satisfactory
mechanical properties, such as flexible tear and
dimensional stability at lower and higher relative
humidities and low temperature.
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In general, a-t least about 40~ by weigh-t of the soft
monomer is employed in order to impart sufficien-t low
temperature flexibility to the polymer sheet. It may be
possible to employ less than 40% so~t monomer. In that
event, plasticizers are often required to provide needed
~lexibility to the sheet. In general, up to about 85~ by
weight of soft monomer can be employed. Preferably, from
about 40% to 85~ by weight of so~t monomex is employed, and
most preferably from about 60% to 80~ by weight of soft
monomer is employed.
In general, in order to provide the minimum desired water
solubility for the polymer in laundry washes containing
detergents or the like, at least about 15% up to about 100%
by weight of water-soluble anionic monomer is employed. As
the amount of anionic monomer employed is increased, it has
been ~ound that the neutralized polymer may become
incrasingly brittle, especially at lower relative humidity
or low temperature. In order to provide improved low
humidity flexible tear properties for the sheet, it is
preferred to employ from about 15% to 50% and, more
preferably, ~rom about 1S% to 40% of the water-soluble
anionic monomer. For best results the ionizable groups of
the anionic monomer after polymerization should be
neutraliz~d up to 100% to achieve solubility. Polymers
with a low proportion of anionic monomer generally require
a high degree of neutralization, and conversely, polymers
with a high proportion of anionic monomer generally require
a low degree of neutralization.
Where the soft monomer employed contains higher alkyl
groups, such as butyl groups, usually higher levels, within
the above noted range, of anionic monomer i5 employed to
provide satisfactory dissolu-tion of the polymer. Under
such circumstances from about 40 to 60% of anionic monomer
may be employed. If desired, a portion of the anionic
monomer may be substituted with a water-soluble nonionic
monomer of the invention.
-- 10 --
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The water-soluble nonionic monomer of the invention can
enhance the water solubility of the addition polymer of the
invention withou-t adding ther0-to ionizable functionalities.
In general, use of the water-soluble nonionic monomer is
discretionary, particularly where the polymer sheet is not
subjected to low relative humidity and/or low temperature.
In general, the particular amount of nonionic monomer
employed is not critical. Usually from about 0 to 40% by
weight is employed, with amounts from about 0 to 15% by
weight being preferred. It is best to employ significant
amounts of nonionic monomer within the broad range when
soft acrylates are utilized having longer alkyl chains,
such as butyl groups or 2-ethylhexyl groups.
The water-insoluble hard monomer of the invention is
employed, as desired within generally broad limits. The
hard monomer has been found useful to reduce the kack of
the resulting polymer at high relakive humidity.
Substantial amounts of hard monomer are not employedl since
they tend to reduce the low temperature flexibility of the
polymer in sheet form. Accordingly, from about 0 to 20% by
weight of hard monomer is employed.
Preferred addition polymers capable of forming self-
supporting films re prepared from the following monomers
having the indicated proportions:
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on~ the factors affecting dissolvability and mechanic~l
properties of -the film is the molecular wei~ht. In
general, as its molecular weight is reduced the mechanical
proper~ies of the polymer may tend to become less
desirable. Furthermore, it has been previously thought
that as the molecular weight of t~ polymer increases and
other factors such as anionic monomer le~el and degree of
neutralization, etc., are held constant, the dissolution
rate-is reduced. Howev~r, it has now been ~ound that
polymers with 15% or more by weight of anionic monomer are
soluble even at very high molecular weight, even though
neutralized up to 100~ or less. Above 15% anionic monomer
the polymer dissolves at a reasonable rate even at cool
wash temperatures of about 60F. In addition, i~ is now
possible, if desired, to improve mechanical proper~ies by
ukilizing a higher molecular weig~t polymer without
sacrificing`solubility.
At high relative humidities (RH), usually above about 75% RH,
sometimes encountered during storage or use it has been found
that the polymer film of the invention may become more tacky.
Polymer sheets may tend to stick to one another, especially
- when stored in a roll or other dispenser type form at high
relative humidity. Accordingly, to reduce and/or eliminate
that tendencyt it may be desirable to employ a barrier coating
on the outer surface of the polymer sheet. The barrier
coating tends to act to insulate the sheet from the effects of
moisture penetration under humid storage conditions.
The barrier coating employed should readily dissolve or break
up when the sheet is introduced into water In one aspect,
suitable barrier coatitlgs generally contaill a film-~orlning
hard component, a plasticizing component and an emulsifier.
Typical ~ilm-forming barrier coatings include paraffin wax and
glyceryl monostearate. Typical plasticizing components
include lanolin and petrolatum, Typical emulsifiers include
stearic acid and the like. The materials referred to above
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inay p~rlor~ lultipl~ L~ tioll~. lor e~alllple, glyceryl
m~llos~earate Inay func~ion both as an emulsifier and as a
film-formillg material, while lanolin may f'unct~on both as an
elnulsi~ier and as a softener. In another aspect, suitable
barrier coatings generally contain a film-forming component, a
plasticizing component, and a component to reduce
cross-linking. A typical film-forming component is
polyvinylalcohol. Typical plasticizing components include
ethoxylated aryl ether nonionic surfactants. Typical
components to reduce cross-linking include ethoxylated
phosphate ester anionic suefactants.
Typical barrier coatings, their method of preparation and
their method of application to a surface are disclosed in U.S.
Patent No. 3,322,674 issued May 30, 1967, U.S. Patent No.
4,390,436, issued June 28, 1983 and U.SO Patent No. 3,257,348,
issued June 21, 1966.
It shculd be understood that the barrier coating need not be
applied to the inner surface of the polymer sheet, which
contacts the laundry care additives, such as a chlorine
bleach. The film-forming polymer of the invention resists the
oxidizing effects of reactive laundry care additives and does
not require an inner barrier coating to protect either itself
or the additive, from deterioration.
In order to assist in providing sufficient low temperature
and/or low humidity flexibility to the polymer sheet to
prevent the polymer from drying out and becoming embrittled,
it may be desirable to employ a plas~icizer in the polymer
composition. Plasticizers are employed which are resistant to
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9~9
the oxidizing and other reactive effects of the laundry
care additives, especially chlorine bleaches. A suitable
pla~ticizer is glyceryl tri~cetate.
Such a plasticizer may be employed in conventional amounts,
usually about 5 to 40 weight percent. Alternatively to
reduce embrittlement it may be desirable to employ in the
polymer, minor amounts oF monomers having relatively low
glass transition temperatures. Such monomers as butyl
acrylate, 2-ethylhexyl acrylate or hydroxyethyl acrylate
may be employed for that purpose.
Optionally, the polymer film could contain filler for
improving physical properties, improving dissolution,
reducing tackiness, increasing modulus, etc. Examples are
talcs, calcium carbonate, polymeric polystyrene ox fibers.
It has been found that the optional inclusion of a small
amount of a solubilizer or surfactant may sometimes be
helpful in aiding dissolution of the sheet during use.
Suitable surfactants may be added to the polymer sheet to
aid in dissolution during the wash cycle and can include
conventional ones s-table to bleaching agents and other
reactive laundry care additives.
The active laundry care additive employed in the laundry
care produc~ of the invention may be selected from the
broad range of typical washing machine additi~es including
enzymes, bleaches, fabric softeners, builders, fabric
conditioners, water sof teners, wrinkle release additives,
additives imparting a specific feel or hand to the laundry
and detergents. A particularly useful active component is
a bleaching composition which may be particulate or in
wafer form.
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~ ficient amounts of such laundry care additives are
employed to provide an effective level when released to the
wash liquor. In general, it has been found necessary to
deliver from about 2 -to 20 grams of additive, especially
bleaching compound, to a typical wash liquor depending upon
for example, the amount of available bleaching species in
the bleaching composition. The actual percentage of
additive in the final sheet will depend upon many factors
including the size and thickness of the sheet. For typical
sheets, the ratio of chlorine bleach to polymer should be
from about 10:1 to 1:2.
The bleaching composition of the invention is a dry chlorine
type bleaching agent. The chlorine bleach may include alkali
metal and alkaline earth metal hypochlorites, hypochlorite
addition products, dimethyldihalohydantoin, chloramines,
chlorimines, chloramides and chlorimides. Specific examples
of such compounds include calcium hypochlorite, chlorinated
trisodium phosphate dodecahydrate, Chloramine T and sodium
dichloroisocyanurate. The preferred bleaches employed are the
chlorinated isocyanurates.
Other suitable bleaches include the inorganic peroxy bleaches
and the organic peroxy bleaches. Typical inorganic peroxy
bleaches are the alkali metal salts of perborates,
persilicates, percarbonates and perphosphates. Suitable
organic peroxy bleaches include urea peroxides or an organic
peroxy acid or anhydride, Suitable aromatic peroxy acids
and/or salts thereof include monoperoxyphthalic acid and
diperoxyterephthalic acid.
The most preferred dry bleaches are the sodium and potassium
dichloroisocyanurates or dichloroisocyanurate dihydrates,
sodium perborate monohydrate, sodiurn perborate tetrahydrate,
sodium percarbonate and rnixtures thereof.
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~._ addition polymer o~ the invention is prepared by
comonomer free radical polym~riza-tion, such as emul3ion
polymerization, solution polymerization, and photo-
polymerization.
Conventional emulsion polymerization techniques are well known
and are described in U.S Patent Nos. 2,754,28~ and
2,795,564. The comonomers may be emulsified, if necessary,
with an anionic or nonionic dispersing agent, about 0.5% to
10~ thereof being used by weight of total monomers. A
polymerization initiator o~ the free radical ~ype, such as
ammonium or potassium persulfate, may be used alone or in
conjunction with an accelerator, such as potassium
metabisulfite or sodium thiosulfate. The initiator and
accelerator, commonly referred to as the catalyst system, may
be used in proportions from about 0.1 to 2%, each based upon
the weight of monomers to be copolymerized. The
polymerization temperature maintained during the reaction may
be from room temperature to about 90C or more.
Examples of dispersing agents, surfactants and emulsifiers
suitable for the polymerization process of the invention
include alkali metal and ammonium salts of alkyl, aryl~
alkaryl, and aralkyl sulfonates, sulfates and
polyethersulfates the corresponding phosphates and
phosphonates and ethoxylated fatty acids, esters, alcohols~
amines, amides and alkylphenols.
To regulate the molecular weight of the emulsion polymers it
is preferred to employ a chain transfer agent, such as a
mercaptan, polymercaptan, or polyhalogen compound in the
polymerization mix. Esters of mercaptoalkanoic acids are
especially preferred as chain transfer agents and,
particularly, butylated mercaptopropionic acid ~BMPA). The
chain transfer agents are used in amounts typically from about
0.2 to 2% by weight. -
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Conventional solution polymerization -techniques are well
known. Monomers and initiators are combined in a solvent-
containin~ reactor. The solvent may be, for example,
methanol for relatively low reaction temperature, and
methyl isobutyl ketone or glycol ether for high reaction
temperature. Temperature may be maintained up to the
boiling point of the solvent chosen. A typical
polymerization initiator may be of the nitrile type, and
may be used from about 0.1 to 5% based on the weight of
monomers to be polymerized.
Conventional photo-chemical polymerization techniques are also
becoming well known. Monomers and photo-initiators are
combined, generally with little or no solvent. The
photo-initi~ator is a chemical compound which absorbs
electro-magnetic energy, generally ultra-violet or visible
light, and produces one or more free radicals capable of
initiating polymerization. The monomer solution, with added
photo-initiator, may be oonverted directly to polymer film by
drawing the solution to the desired thickness and then passing
it under a source of ultra-violet light to initiate the
polymerization. Typical photo-initiators may be benzophenone
or derivatives, with or without added amine synergists~ or
acetophenone derivatives, and may be used from about O.al to
5% on the weight of monomers to be polymerized. A typical
source of ultra-violet light is a medium-pressure mercury
vapor lamp with power of 300 watts per inch.
Polymer Preparation Example
The addition polymers of the invention may be prepared as
follows:
A reactor is partially filled with deionized water and heated
under nitrogen feed to a temperature from about 8S-95C. An
aqueous solution of the initiator an~, optionally, emulsifiers
~, '.
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~.~7~3~7~3
are thereafter introduced. rrhe reactor i~ then reh2ated to
the reaction temperatu:re, as needed, and the comonomers
feed is introduced. Tlle comonomers feed includes all the
comonom0rs of the invention and the chain transfer agent.
The comonomers feed is preferably a delayed feed over a
period of from 1 to 2 hours. ~uring that time the desired
reactor temperature is maintained.
After all the monomers have been introduced into the reactor
the polymerization mixture is held for about 45 minutes at the
reaction temperature to ensure completion. Thereafter, the
reaction mix is cooled and the latex filtered off. A
neutralized polymer formulation is prepared by adding thereto
sodium hydroxide solution or the like to neutralize the
polymee to ~up to 100% of theoretical.
If desired, the addition polymers of the invention can also be
prepared by appropriate solution polymeri~ation techniques.
Such techniques can include a delayed two hour addition of
comonomers containing initiator to a Cellosolve (reaction
solvent) - containing reactor at reaction temperatures of
about 115C. After the monomer feed is completed, additional
initiator is added to complete polymerization.
Neutralized polymer films are prepared from high solids
neutralized solutions of the polymer by casting or extruding
techniques. For example, a polymer film of the invention may
be prepared by drawing down a high non volatiles (25% N.V.)
neutralized polymer on a polyethylene film with a Gardner
knife or the like and, thereafter, drying the polymer film for
1 hour at 95C. The dried polymer film is peeled from the
polyethylena backing and thereafter employed as a polymer
sheet for retaining a laundry care additive of the invention~
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If desired, the solid polymer may b~ r~covered from a latex
or a solution employing a wiped film evaporator or the
like. The solid polym~r may be trea~ed with base in ~
Banbury-type mixer, extruded, remaining water removed by
venting and the molten ionomer extruded as a sheet. A
laundry care additive is di~pensed to the sheet, a second
sheet is placed on top of the first to form a sandwich or
the first sheet folded over the additive and the resulting
package heat sealed.
Again, if desired, the polymer of the invention can be
prepared by appropriate photo-polymerization techniques. The
chosen monomers are combined in the desired proportions, with
added solvent if desired. The neutralizing base, for example
sodium, lithium, or potassium hydroxide, is adde~d in the
amount needed to achieve the desired degree of neutralization
of the anionic monomer. Water may be added if needed to
assist in solubilizing monomer salts in the monomer solution.
A surfactant, for example sodium lauryl sulfate, may be added
if needed to solubilize or emulsify any of the components of
the monomer solution. Plasticizer, for example glyceryl
triacetate, may be added if desired to enhance mechanical
properties of the polymer. The photo-initiator is dissolved
in the monomer solution. The monomer solution is cast to the
wet-film thickness needed to achieve the desired dry-film
thickness, and is then passed under a source of ultra-violet
light for a time sufficient to ensure complete
polymerization. A laundry care additive is dispensed to the
sheet, a second sheet is placed on top of the first to form a
sandwich or the first sheet folded over the additive and the
resulting package heat sealed.
It is important that the laundry care additive form a
relatively thin, preferably monoparticulate layer, retained
within the polymer sheets~ If any pockets of additive remain
on the laundry product, then upon handliny, the pockets may
cause the sheet material to rupture. Accordingly, the product
-20- ,
~ ~9~7~3
`lould be formed to prevent formation of additive pockets
or cells and to p~on~ote formation of a thin,
monoparticulate layer of additive anchored wi~hin the
product.
For that purpose the laundry care additive is uniformly
dispensed to a polymer sheet, either as particles or as
wafers. The polymer sheet may then be folded upon itself or a
second sheet may be applied over t~le dispensed additive.
Thereafter under relatively mild conditions of heat and
pressure, the layers of sheet material containing dispersed
additive are joined to themselves and to the dispersed
particùlate or wafered additive therein to form a unitary
monolithic matrix. It is a key advantage of the present
invention that the laundry product is a unitary matrix or
laminate intimately anchoring and retaining the additive
particles or wafers, thus preventing formation of pockets or
cells of additive.
During sealing, the polymer sheet softens and flows at least
in part into the interstices or voids between the additive
particles or wafers, thus anchoring and retaining them against
movement and permanently uniting the polymer sheet and the
particles or wafers into a single unit.
In a preferred embodiment the sealing conditions and the
thickness of the sheet employed is controlled to permit the
film to flow substantially into the interstices between the
dispersed particles or wafers. If desired, in another aspect
of this invention the sealing conditions are adjusted to allow
the film to colnpletely fill the void spaces and to thereby
encapsulate the particles or wafers. In another embodiment
the sealing conditions are selected to allow the film to
merely tack or bind the particles or wafers within the unit
with little film flow into the interstices.
-21-
~5 "
- : . .' ': . '
,
~, ~7gt749
~ sir~i, wll~r~ laulltlry ~ar~ iitiv~s are ~nll7loye~ wl~icl~
ar~ t wat~r sensitive, such as c~rtain fa~ric so~teners an~ -
detergents, suc~l additives can ~e dispersed~or mixed into the
latex or solution at any stage before oe after polymerization
is complete, and the entire mix of polymer and additive may be
formed into a unitary sheet ~y extruding, film casting or the
like, In ~his embodiment the additive may be embedded in the
surface of, or even completely within, the sheet matrix.
For best results the product is formed by joining a folded
over sheet or two sheets, containing additive therein, at
temperatures preferably ~eom about 80-120C. The pressure and
temperature selected will depend, in part, on the identity of
the monomers employed in the polymer film.
In general, a laundry product of the invention is usually
from about 32 to 516 sq. cm. (about 5 to 80 square
inches~in area, preferably 64 to 129 sq. cm.(10 to 20
square inches), to provide adequate storage space for the
additive, although larger and smaller sheets may be
employed. The laundry product should be thin enough to
dissolve or disperse in warm water in about 20 minutes or
less. The product should be thick enough however, to
provide proper support.
For these and other purposes, it is preferred that the
individual polymer sheets be from about oO0254~~0254
cm.~about 1-10 mils), preferably .00508-.01524 cm.(2-6
mils) in thickness. If desired, multiple layers of polymer
films can be joinecl to form a single sheet.
,The following examples are provided for ilLustrative purposes
only and sh~uld not be dee~ed to he limitative of scope. In
the following examples all parts and percentages are by weiqht
unless otherwise indicated.
- 22 -
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. - . - , .
. . ' ',
- , . . ~ '
9~7~3
lAxalnple _l
A polymer was prepared of the following coinposition: 94%
ethyl acrylate/6~ acrylic acid, neutralized to 150% of
stoichiometric with l.l equivalents of sodium hydroxide and
0.4 equivalents of sodium bicarbonate.
900g of de-ionized water is charged to a 2-liter flask. The
water is heated under a nitrogen atmosphere to 85C. l.5g of
ammonium persulfate is dissolved in 50g of de-ioniZed water
and added to the flask; the solution is re-heated to 85C. A
monomer feed is prepared o~ 470g ethyl acrylate, 30g acrylic
acid, and 5g butylated mercaptopropionic acid. This feed is
added to the flask over a 90 minute period, contlnuously
stirring and maintaining 85C. The latex is stirred an
additional 60 minutes at 85C, then allowed to cool to room
temperature. The latex is about 34~ non volatiles. 18.32g
sodium hydroxide is dissolved in 250g de-ionized water, then
slowly added to the latex. 13.99g sodium bicarbonate is added
and stirred until dissolved. The latex is now about 29%
non~volatiles, and the polymer is 150% neutralized.
The neutrali~ed latex was drawn down onto a sheet of
polyethylene film and air-dried; the dry film was about
.02032 cm. (about 8 mils)thick. A bleach sheet was made by
cutting two pieces of film 7.62 cm. x 10.16 cm. (3ll x 4").
One piece of film was placed on a sheet of silicone release
paper. 3g of sodium dichloroisocyanurate dihydrate (*ACL
56, from Monsanto) was sprinkled uniformly over the film.
A second piece of film was laid over the ACL 56, and a
second sheet of silicone release paper was placed on top to
form a sandwich. The sandwich was placed between -the
plates of a heated press, then heated for 30 seconds on
each side at 90C and 1.05 kg. per sq. cm.(15 psi), forming
the bleach sheet by heat-sealing the polymer film layers
together around the ACL 56 granules; the silicone release
paper was removed. The bleach sheet was coa-ted on both
sides with a thin moisture-barrier coating of 4 parts
stearic acid : 1 part paraffin, then lightly dusted with
talc.
* denotes trade mark
- 23 -
' ''
~ J'`79~7~3
ilicone release paper was removed. The bleach ~heet was
c~ated on both sides with a -thin mo,is-ture-barrier coa-ting of 4
parts stearic acid: 1 part paraffin, -then lightly dusted with
talc.
The bleach sheet was stored at 32.2~C (90F3 and 75% R.H.
After one week the sheet lost 11.6~ of its available
chlorine; the loss after four weeks was 28.3%.
EXAMPLE 2
Polymer films were prepared as in Example 1, except that
the polymers were neutralized to 110%, 130% and 1~0%,
respectively, with lithium hydroxide. Bleach sheets were
prepared from these films as in Example 1, using 5g ACL 56
per 7.62 cm~ x 10.16 cm. (3" x 4") sheet. The sheets were
stored at 90F and 75% R.H. The sheet neutralized to 110~
lost 14.4~ of its available chlorine after 7 days; the 130%
sample lost 14.1% after 6 days (or about 16.4% at 7 days3;
the 150% sample lost 17.4% after 7 days. The chlorine
stability of the bleach sheet clearly decreases with ',
- increasing pH and degree of neutralization.
E~AMPLE 3
A series of polymers of composition 84~ ethyl acrylate/10%
hydroxyethylmethacrylate/6~ acrylic acid was prepared by
the procedure of Example 1; the amount o-f BMPA was varied
so as to vary the molecular weight; all polymers were
nelltralized to 120~ with sodium hydroxide. The following
results were recorded :
- 2~ -
. .., ~; ,~,
.
,
:- - ' , .
'. ' ' ' :
,
'3
(l)Moleculdr BMl~A, as ~ (2)D~y ~ilm
Weight _ of Polvmer pH _ Tear Soluhility @15.5C (60F)
20,490 2.0010.00 4 Dissolved in 45 seconds
- 25,490 1.5010.20 3 Fine particles in
135 seconds
29,170 1.00 9.76 2 Dissolved in 120 seconds
46,230 0.75 8.81 1 Flakes after 600 seconds
62,390 0.50 9.05 1 Small and large flakes
~103,200 0 10.00 1 Largely intact, some
! medium flakes
(1) Weight average molecular weight as measured by GPC. The
highest sample had much insoluble matter, so molecular weight
is higher than 103,200.
(2) Dry film tear is measured by slowly stretching a dried
polymer film and observing the nature of the tear which
occurs. Generally there initially occurs a uniform increase in
the size of the tear followed by a sudden rupture~ Lower
values show greater elongation before rupture, and are more
desirable.
These results clearly show that polymer film properties improve
as molecular weight increases. They also clearly show that,
even with over-neutralization of the polymer, it is nearly
impossible to maintain polymer solubility with increasing
molecular weight at low proportions of water-soluble anionic
monomer.
EXAMPLE ~
A polymer was prepared of the following composition: 40% ethyl
acrylate/4o% butyl acrylate/20% acrylic acid, neutralized to
95% of stoichiometric with sodium hydroxide.
-25-
.
',. , : ~ ''
~L~7~4~3
To a 3-liter flas~ equipped with a dropping funnel and
condenser, chaege 750g methallol, 409 ethyl acrylate, 40g butyl
acrylate, and 20g acrylic acid. Start heating under nitrogen
atmosphere to reflux. While heating, but be~ore reflux, charge
0.2g 2,2'-azobis (isobutyronitrile) ~Vazo 64, DuPont) dissolved
in 509 methanol. Maintain reflux 15 minutes, then start
dropwise addition of monomer eed consisting of 200g methanol,
160g ethyl acrylate, 1609 butyl acrylate, 80g acrylic acid, and
0.7g Vazo 64; monomers should be added over a 90-100 minute
period. Maintain reflux another 90 minutes, then add 0.5g Vazo
64 in lOg methanol. Continue stirring and reflux under
nitrogen for total of 24 hours, add 90g of methanol, and cool
to room temperature. Polymer solution is now about 31.2%
non-volatiles. The polymer is neutralized by slowly adding
52.7g sodium hydroxide in 400g de-ionized H2O, The polymer
solution is now about 25~ non-volatiles. The weight average
molecular weight was 217,830.
A polymer film and bleach sheet were prepared a~ in Example
1 with 2.5g ACL 56 per 5.08 x 7.62 cm. (2" x 3") sheet, no
coating was applied. The film is strong and flexible, and
i9 soluble in 47.7C (60F) tap water. The bleach sheet was
stored at 90F and 75% ~.H.; after 1 week it lost 0.8% of
its available chlorlne, and after 4 weeks it lost only 3.3%.
Clearly, usin9 a higher proportion of anionic monomer has given
several significant improvements over prior polymers:
-higher molecular weight gives good film properties
-suprisingly, the polymer is very soluble even though
it has high molecular weight and is neutralized less
than completely
-the bleach sheet is dramatically improved as to
chlorine stability compared to prior polymers.
-26-
. . ' ~
749
EXAMPLE 5
A series of polymers w~re prepared, as outlined in the
table below. Emulsion polymers were prepared by the
technique of Example l; solution polymers were prepared as
in Example 4. All polymers were neutralized, as specified
in the table below, by dissolving the base in sufficient
de-ionized water to reduce the final polymer concentraiton
to 20-25~ by weight and adding the base solution to the
polymer solution. Polymer films were prepared as in
Example 1, with thickness .0127-.0254 cm. (5-10 mils).
Some of the bleach sheets were prepared as in Example 1,
with 5.0 g ACL 56 granules per 7.62cm X 10.16 cm. (3" x 4~')
sheet. Other of the bleach sheets were heat-sealed in the
same manner, but the ACL 56 was used as six 0.95 gram
portions per 7.62 cm.x 10.16 cm. (3" x 4") sheet, each
portion having been pressed in a tablet press into a wafer
25 mm diameter by 1.2 mm thick, the wafers uniformly spaced
over the sheet~ None of the bleach sheets had a moisture-
barrier coating.
,
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-28-
. . '
.
'7~9
These resul.ts clearly show the here-tofore unrecognized
advantages of making bleach sheets from polymers which have
greater than 15% anionic monomer. These polymers are
completely soluble, even at 15.5C (60F), regardless of
molecular weight, even though they may be less than 100%
neutralized. Furthermore, by using such polymers, -there
has been achieved a substantial reduction in the loss of
chlorine during storage, particularly at high temperature
and humidity.
Example 6
A polymer was prepared having this composition: 60% butyl
acrylate/40% acrylic acid, neutralized to 50% of
stoichiometric with sodium hydroxide.
To a 3-liter flask equipped with a dropping funnel and
condenser, charge this initial monomer blend: 60g butyl
acrylate, 40g acrylic acid, 575g methanol, and 0.12g *Vazo
64. Under nitrogen atmosphere heat to reflux. Agitate at
reflux for 15 minutes, then over a 90 minute period add
this monomer feed: 240g butyl acrylate, 160g acrylic acid,
250g methanol, and O.SOg Vazo 64. Agitate at reflux under
nitrogen for another 90 minutes, then over a final 30
minute period add the final initiator feed: lOOg methanol,
0.20g Vazo 64. Continue to agitate at reflux for 20 hours
after the final feed, then cool to room temperature. The
unneutralized polymer solution will be about 35% solids.
The weight average molecular weight is 145,800.
The polymer is neutralized to 50~ of stoichiometric by
slowly adding 1387.7g of 4.0% aqueous solution of sodium
hydroxide. The partially-neutralized polymer solution is
now about 18% solids. A plasticizer is added by adding 50g
glyceryl triacetate to the solution.
* denotes trade mark
- 29 -
~; ,
.- ..
.. -' '
9~9
Polymer film and bleach sheets were prepared as described
in Example 1, using 5.0 g ACL 56 granules per 7.62 cm. x
10.16 cm. (3~' x 4~) shee~. The film is flexible at room
temperature, and is completely soluble in 15.5C (60F) tap
water. Bleach sheets were stored at 90F and 75~ R.H.
After 2 weeks there was 6.0% loss of available chlorine.
Additional bleach sheets were made, using ACL 56 wafers
rather than granules. Each 7.62 cm. ~ 10.16 cm. (3~ x 4
sheet has 6 wafers, each containing 0.93g ACL 56 and
measuring 25 mm diamter by 1.2 mm thick; wafers are made in
a conventional rotary tablet press. Wafer-containing
bleach sheets are heat-sealed as in Example 1, sealing for
5 seconds at 121.1C (250F and 2.81 kg. per sq.cm.(40 psi).
The bleach sheets were stored at 90F and 75% R.H.; after 4
weeks there was 3.4~ loss of available chlorine, and after
8 weeks the loss was 7.0%.
EXAMPLE 7
A polymer was prepared using the same composition and
technique as Example 6, except that it was made with
overall batch size 45.36 kg. (100 lbs.) at 35% solids. The
resulting un-neutralized polymer had weight avPrage
molecular weight about 350,000 It was neutralized to 50%
of stoichiometric with sodium hydroxide solution using the
procedure of Example 6. 3.17 kg.(7 lbs.) of glyceryl
triacetate was added as a plasticizer. Film was cast and
air-dried as in Example 1, to a dry film thickness of .027
cm. (5 mils.). The film is completely soluble in 15.5C
(60F) tap water.
An anti-tack coating was applied to one side of the film to
prevent tackiness which may develop at high temperature and
humidity. The coating is 75% partially hydrolyzed
polyvinylalcohol (*Vinol 205l from Air Products), 10%
* denotes trade mark
- 30 -
~, . . .
:
7~9
nonionic polyoxye-thylene arylether (*Pycal 94, from
I.C.I.), and 15~ anionic phosphate e~ter (*Gafac LO 529,
from G.A.F.). It is prepared aq a 25% solution in water,
rolled onto the film with a #16 wire-wound rod, and air-
dried.
Wafer-containing bleach sheets containing 6 wafers in each
7.62 cm. x 10.16 cm. (3 x 4~l) bleach sheet were made as in
Example 6, except that each wafer contained 0.833g ACL 56
0.151g sodium acid pyrophosphate, O.OlOg magnesium
stearate, and 0.006g of a fluorescent whitening agent
(*Tinopal CBS-X, from Ciba-Geigy); sheets are made such
that the coating on the film is at the outside of the
bleach sheet.
Both the film and the bleach sheet are completely soluble
in 15.5C t60F) tap water, and are very flexible even after
24 hour~ in a refrigerator at 4.4C (40~F). Bleach sheets
were stored at 32.2C (90F) and 75% R.H.; after 1 week
there was 0.8% loss of available chlorine, and after 2
weeks the loss was only 3.0%.
.
EXAMPLE 8
A polymer was prepared having the following composition:
60~ butyl acrylate/40% acrylic acid, neutralized to 70% of
stoichiometric with potassium hydroxide.
An initial monomer solution is prepared by combining 60g
butyl acrylate, 40g acrylic acid, 20g methanol, 21.7 g
potassium hydroxide, 3.0g sodium lauryl sulfate, and O.lOg
2,2-dimethoxy-2-phenyl-acetophenone (a photoinitiator,
*Irgacure 651 from Ciba-Geigy). To 50g of this solution is
added as a thickener 15g of the un-neutralized polymer
solution prepared as in Example 7 (except made at 45%
solids) and 1.4g additional potassium hydro~ide; the
monomer solution is quite viscous. The monomer solution is
- 31 -
'' , ' ' ~
3~7qL9
drawn with a Gardner knife on a glass plate to a film
thickness about .010 cm.~4 mils.), then passad undar a 30n
watt~per-inch medium pre~ure mercury vapor lamp at a 3peed
of 13.7 meters-per-minute (45 feet-per-mlnute~ to produce
the completely cured film. The requlting film i~ .0101
cm.(4 mil~.) thick, i~ very tough and flexible, and i~
completely soluble in 15.5C ( 6 0F ) tap water.
.
* denotes trade mark - 32 -
.
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