Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to detergent bars an~ especially
to the provision o~ detergent bars having a basis of fatty acid
soap as the predominant wash-active agent nnd having improved
resistance to wet cracking and embrittlement.
There exist a number of prior art disclosures o~ soap
bars in which polycarboxylic acids, including aliphatic
dicarboxylic acids, have been incorporated for various purposes.
Thus, U.S. 1,6O4,336 of ~ept. 11, 1928 discloses a medicinal soap
bar containing rectified amber oil and about 2~ of succinic acid
to provide hyperaemia with consequent heating. U.S. 2,792,348
of May 14, 1~57 discloses the addition of 1% to 10'~ of aliphatic
dibasic acids of 3 to 10 carbon atoms as a hardness - incrensing
agent in soap bars, especially those derived from unsaturated
fatty acids,U.S. 3,o85,066 of April ~, 1963 discloses the use of
about 0.01% to 0.5%, up to lO~o ~ of an alkanedioc acid of 2 to 10
carbon atoms a5 a color stabilizer in an antisepti~ soap bar
containing a discolorin~ type of bacteriostat. U.S. 3,557,()06
of Jan. 1~, 1971 discloses the very same dibasic acid-containing
soap bars as U.S. 2,792,348 but the acid is relied upon to provide
on tlle skin the normal acidic skin p~ ritish 481,481 accepted
March 11, 1~38 discloses the addition to soap bars bleached with
boric acid of a very small amount (about 0.1%) of a hydroxypoly
basic aliphatic acid such as tartaric or citric acid for neu-trali-
zation of excess alkali and to provide resistance to discoloration 9
cracking and embrittlement. British 1,460,442 published Jan. 6,
1977 discloses soap bars containing, as skin moisturizersl 5 to 55%
of C4 10 aliphatic dicarboxylic acids and/or hydroxy polycarboxylic
acids. U.K. Patent Application GB 2,oo4,5~4A published Apr. 4, 1~7
discloses the concept of reacting a neutral fatty acid soap wi-th
about O.l~o to 3% of a C3 10 aliphatic dicarboxylic acid which
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yields the corresponding soap o the dicarboxylic acid and con-
currently releases an equivalent desired amount of free (super-
fatting) fatty acid. In South African Patent No. 80/7894 issued
July 28, 1982 soap bars are disclosed containing, as anti-wet
cracking agent, about 1% to about 5% of adipic, azelaic or
tartaric acid. In South African Patent No. 80/7779 issued July
28, 1982 soap bars are disclosed containing, as anti-wet crack-
ing agent, about 1~ to about 5~ of a mixture of C4 20 poly-
carboxylic acids, at least 20% of the mixture comprising
straight chain dicarboxylic acid of no more than 9 carbon atoms.
Wet-cracking refers to the known defect of soap bars in develop-
ing cracks when repeatedly moistened and dried.
Such soap bars containing polycarboxylic, and especi-
ally dicarboxylic, acids are however more or less disadvantage-
ous for several reasons. Thus, it has been found that these
acids tend to make the soap "short" or brittle upon extrusion,
thus showing its non-plasticity. Furthermore, these acids have
high melting points and in their original state are hard dry
particles not readily miscible with the soap during processing.
This reduced miscibility not only renders the processing more
difficult and costly, but also reduces the anti-wet cracking
efficiency of the acid in the soap bar. These acids also tend
to reduce the water solubility and/or lathering properties of
the soap bar, especially in cold, hard water. Further, these
soap bars, being still on the alkaline side because of the rela-
tively small amount of acid contained therein, exert a recognized
degree of skin irritation in use.
It is an object of this invention to provide soap bars
and methods of making them which will not be subjec-t to one or
more of the above disadvantages. Other objects and advantages
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will appear as the description proceeds.
The attainment o~` the above ob~ects is ma~e possible
by this invention which includes the provision of a detergent
bar comprising, approximately by weight, at least 70~ of a C8 20
fatty acid salt, 0.5% to less than 5% of one or a mixture of
hydrocarbyl or hydroxyhydrocarbyl polycarboxylic acids of 2 to
about 20 carbon atoms, and 1% to less than 25% of one or a
mixture of ethoxameric nonionic surface active agents.
According to another aspect of this invention, a
preferred method for making the aforementioned detergent bar
cornprises dissolving the polycarboxylic acid in the nonionic
surface active agent and mixing the resulting sclution with the
fatty acid salt.
According to yet another aspect of this invention, a
washing method is provided comprising contacting the human body
with the aforementioned detergent bar in the presence of water.
The nonionic surface active agent included in the poly-
carboxylic acid-containing detergent bars of this invention
reduces or eliminates the tendency of the bars to become brittle,
furtller improves their resistance to wet-cracking, improves their
solubility and la-thering properties in use in water, especîally
cold, hard water, exerts an emollient or anti-irritation effect
on the skin, and renders the soap composition more pl~stic and
more easily and economically processed into bars. Pre-dissolving
the polycarboxylic ncid nnti-wet cracking agent in the nonionic
surface active agent further facilitates uniform mixin~ into the
soap composition and improves the efficiency of the anti-wet
cracking agent in the bar.
~he predominant wnsh-active n~ent in the detcreent bnrs
3 ol this illVClll;iOIl m/ly be nlly COIIIVelltiOnal sonp, Ol,ll^L'WiS(' I`CI`('rl`eU
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to as fatty acid .;alt. The soap may be derived from one or a
mixture of C8-20~ preferably C12_18, straight or branched chain,
saturated or unsatura-ted monocarboxylic acids, of nnturnl or
synthetic origin. Natural sources, e.g. animal, marine or
,vegetable fats and oils, almost always yield mixtures of these
fatty acids, all of which may be employed. Examples thereof
include the fatty acids derived from coconut oil, olive oil,
palm kernel oil, tall oil, soy bean oil, cottonseed oil, peanut
oil, safflower oil, sunflower seed oil, corn oil, Pish oils,
tallow, and the like. Illustratively, indiv;dual fatty acids
include capric, lauric, myristic, stearic, oleic, palmitoleic,
ricinoleic, linoleic, linoleric acids and tile like. The fatty
aolds may also be derived synthetically by paraffin oxidation,
Oxo-synthesis, or the like. The cation or salt portion of the
soap is preferably an alkali metal such as potassium and,
especially, sodium, but may alternatively be an alkaline earth
metal such as calcium or magnesillm, ammonium, substituted
ammonium, or organic amine such as lower alkylamines and lower
alkanolamines. Mixtures of the fatty acids may be employed.
Preferred are 4/1 to 7/1, especinlly nbout 3/1 to 5/1, tallow/coco
sodium soaps. The fatty acid salt typically constitutes a-t least
about 70%, preferably at least about 80%, by weight of the
detergent bars of this invention.
The polycarboxylic acid component may be unsaturated but
preferably saturated, and aromatic, alicyclic but preferably
aliphatic, branched but pre~erably straight chain, and hydroxy-
substituted but preferably unsubstituted, and hexa-, penta-, tetra--,
tri- but preferably di-carboxylic, and of 2 to about 20, preferably
2 to a,bout 10, carbon atoms. Alkanedioc and hydroxyalkanedioc
acids of 2 to about 10 carbon atoms are especin1ly ~reI'erre(l,
-5
particularly adipic nnd a~elaic acids. ~s illustratlve of other
suitable hydrocarbyl and hydroxyhydrocarbyl polycarboxylic acids,
there may be mentioned oxalic, malonic, succinic, glutaric,
pimelic, suberic, sebacic, methyl adipic, citric, malic, tartaric,
dihydroxy~ar-taric, fulllaric, maleic, itaconic, aconitic, hexerledioc,
heptenedioc, phthalic, 3-hydroxyphthalic, cyclohexyldicarboxyli
3-cyclohexyl- dicarboxylic, melli~ic, hexahydromellitic, mello-
phanic and the like. Mixtures of two or more such acids may
be employed. The polycarboxylic acid component, which may
optionally be in anhydride form and/or at least partiallY in
salt form, typically constitutes about 0.5% to less than 5S',
preferably about lS~ to about 3%, by weight of the detergent bars
of this invention.
The nonionic surfactants (sur*ace active agents) useful
in the present invention are well known materials and may be
broadly defined as water soluble products derived from the
condensation of a plurality of moles of a C2_3 alkylene oxide
or equivalent reactant (hydrophilic in nature) with n reactive
hydrogen-containing organic llydropllobic compound which may be
aliphatic, aromatic, alicyclic or heterocyclic. The length of
the hydrophilic polyoxyall~ylene chain in the condensation product
derived from any particular hydrophobe can be readily adjusted
to provide water solubility and the desired degree of balance
between hydrophilic and hydrophobic or lipophilic elements
5 (HLB factor). Although propylene oxide may be employed as the
alkylene oxide reactant,
ethylene oxide is most commonly emp'oyed, more effective and
preferr~d herein. These polyoxyethylene-containing condensation
products have been referred to as ethoxamers or ethoxameric
0 nonionic surfactants.
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The precursor hydrophobe of the nonionic surfactant
may contain from about 6, preferably from about 8, up to 50 or
more carbon atoms and at least one reactive hydrogen~containing
moiety as present for example in aliphatic alcohols, alkyl
phenols, carboxylic acids, carboxylic acid amides, sulfonamides,
amines, and the like. As a general rule, at least about 4 moles
of ethylene oxide should be reacted per mole of hydrophobe, but
up to 200 moles of ethylene oxide may be so reacted depending on
the hydrophobe, desired water solubility, surface activity,
emolliency, plasticity and melting point, and the like. The non-
ionic surfactant should be liquifiable, e.g. at elevated tempera-
tures up to about 90C, to facilitate processing o the soap com-
position into bar form.
Representative operative nonionic surfactants include
polyoxyethylene polyoxypropylene block polymers ~Pluronics)* and
other types as disclosed for example in the portion of U.S.
4,140,641 issued February 20, 1979 to Ramachandran from line 3
to line 63 of column 2. As exemplary of specific nonionic sur-
factants, mention is made of dinonyl phenol + 15 E.O. (1 mole of
dinonyl phenol reacted with 15 moles of ethylene oxide), dodecyl
mercaptan + 10 E.O., lauramide + 8 E.O., stearic acid + 20 E.O.,
tetradecyl amine + 14 E.O., dodecyl sulfonamide + 6 E.O., and
myristyl alcohol + 10 E.O. Preferred are condensation products
of one mole of an alkanol, preferably straight chain and primary,
of about 9 to 20, especially 10 to 18, carbon atoms ~ith about
4 to 20, especially 5 to 15, moles of ethylene oxide, as repre-
sented for example by Neodol* 23-65 (C12 13 alkanol + 6.5 E.O.)
and Neodol 45-13 (C14_15 alkanol + 13 E.O.). The nonionic sur-
factant component typically constitutes about 1% to less than
25%, preferably about 2 to less than 10%, more preferably about
2.5% to less than 5%,
* Trade Mark
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by weight of the detergent bars of this invention. As indicated in
the examples below, inclusion of this nonionic surfactant component
in polycarboxylic acid--containing detergent (soap) bars enables the
attainment of equal or better resistance to wet cracking with a
substantially lower proportion of the polycarboxylic acid.
The nonionic surfactant/polycarboxylic acid weight ratio
preferably ranges from about 0.5/1 to about 5/1, more preferably
about 1/1 to about 2/1, especially about 1.5/1.
The detergent bars of this invention generally contain
about 8% to about 16%, more usually about 10% to about 14~, by weight
of water, and optionally other conventionnl additives suc~h as super-
fatting agents, perfumes, coloring matter, anti-oxidants, non-soap
organic anionic surfactants, proteins, binding agent~ sequestrants,
foam boosters, optical brighteners, preservatives, bacteriostats,
and inorganic salt fillers and builders and the like in conventional
proportions of about 0.01% to about 25% by weight of the detergent
bar.
In preparing the detergent bars of this invention, the
polycnrboxylic acid and nonionic surfactant components may be
incorporated into the sonp nt nny stnee of processi~g into bal forrll,
preferably by admixture with -the previously prepared
soap chips in the crutcher or, more preferably, the amalgamator.
According to a further feature of the invention, the polycarboxylic
acid component is first dissolved or dispersed in the liquid or
liquified nonionic surfactant (e.g. by heating up to about ~0C. if
needed) and the resulting solution (or dispersion) then admixed
with the fatty acid salt-containing soap composition, followed by
conventional extrusion and pressing into bar form.
The wet cracking test, results of which are given in the
following ex~mplcs, lnvolvcs immersing the bar (Or a~out :L0() grams)
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in water at llbou~ 24C~ for l~ hours, removine and hanging the bnr
to dry and thell evaluating for cracks. The severity of the cracks
are rated on a scale of 0 to 5, no cracks of any kind being assigned
a severity rating of 0~ very tiny cracks being assigned a severity
rating of 1, larger cracks 2 to 4 depending on size, and 5 when the
bar is badly cracked or split. The severity rating multiplied by
the number of cracks is the cracking rating, averaged for reliability
on a substantial number (e.g. 31) of bars concurrently produced
from the same composition.
The following examples are only illustrative. ~11 amounts
and proportions referred to herein and in the appended claims are
by weight unless otherwise indicated.
Example 1
A solution of 2 parts by weight of adipic acid in 3 parts
by weight of Neodol 23-6.5 (C12_13 alkanol + 6.5 EØ) is prepared
at about 65C. The solution is then processed in a conventional
amalgamator with, approximately by weight, ~2 parts of 5/1 tallow/
coco sodium soap chips of 11% moisture content, 0.1 parts of 50%
aqueous stannic chloride (color and fragrance stabilizer), 0.5 parts
of titanium dioxide, 1.25 parts of bacteriostat, 0.5 parts of
glycerin, 1.5 parts of' perfume, and 0.5 parts of A 10~ color
solution. The mixture is then shaped into bars of about 100 grams
each in conventional manner including extrusion and pressing, and
tested for wet cracking as described above, together with control
bars made in similar manner but withou-t the Neodol nonionic surfactant
and adipic acid. The control bars are found to have an average
cracking rating of 51 compared with an average cracking rating of 0
for the bars containing nonionic surfactant and adipic acid. By
comparison, in Example 2 Or the above-mentioned application Serial
No. 105,806 filed Dec. 20, 1~7~, a substantially similar soap bar
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con-taining 2% adipic acid but no nonionic suractant is indi-
cated to have an average cracking rating of 3.
Example 2
Example 1 is repeated substituting 2 parts of azelaic
acid for the adipic acid. These bars are likewise found to have
an average cracking rating of 0. By comparison, in Example 1 of
said South African Patent No. 80/7894 a substantially similar
soap bar containing 3.5~ azelaic acid but no nonionic surfactant
is indicated to have an average cracking rating of 1.
Example 3
When Examples 1 and 2 are repeated using Neodol 45-13
(C14 15 alkanol + 13 E.O.) instead of Neodol 23-6.5, substanti-
ally similar results are obtained.
Example 4
When Examples 1, 2 and 3 are repeated using as the
soap chips 3/1 tallow/coco sodium soap chips of 13% moisture con-
tent, substantially similar results are obtained.
This invention has beèn disclosed with respect to pre-
ferred embodiments thereof and it will be understood that modi-
fications and variations thereof obvious to those skilled in theart are to be included within the spirit and purview of this
application and the scope of the appended claims.
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