Note: Descriptions are shown in the official language in which they were submitted.
B~CKGROUND OF TIIE_INVENTION
The wet cracking of soap, i.e.3 the tendency of soap to form cracks
when moistened and dried, particularly during use, has been an ever present
problem. In United States patent 2,414,098 wet cracking is discussed but it
is alleged to be minimi~ed by mechanical processing techniques, In United
States patent 4,814,807 there is disclosed the use of branched chain C12 to
C20 alkanols as well as di-octyl adipateJ the latter having up to 50% of
n-octyl groups to improve wet cracking. In United States patent 2,792,348
there is disclosed the use of sodium salts of C3 to C10 di-basic acids as an
additive to soap to produce a harder soap from a given fatty acid or fat and
at a given moisture content. In United States patent 3,557,006 certain low
molecular weight di-basic acids are disclosed as a basis for a soap to be used
as an additive to soap to produce a harder soap product. In United States
patent 4,151,105 lactic acid and citric acid are disclosed as useful organic
acid to adjust downward the pH of a synthetic detergent-containing ~other than
soap) bar to within a pH of 5.0 to 7Ø In British 1,460,442 there are dis-
closed detergent bars containing as a moisturi~ing component inter alia, 5 to
50% by weight of an acyclic C2 to C8 hydrocarbon dicarboxylic acid which may
be linear or branched. It is an object of this invention to provide soap com-
positions in shaped form and particularly in bar form which have improved wetcracking resistance.
It is a further object of this invention to provide soap compositions
of improved wet cracking resistance and otherwise acceptable for personal
washing.
Ano~her object of this invention is to provide soap bars of impro~ed
resistance to wet cracking and of improved lathering characteristics.
Still another object of this invention is to provide processing for
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making soap bars of improved lathering properties.
Accordi.ng to the present invention, there is provided in a detergent
bar comprising a C8 to C20 fatty acid salt, the improvement wherein from about
1% to about 5% by weight based on the weight of detergent of a mixture of at
least two polycarboxylic acids of 4 to 20 carbon atoms and wherein at least
20% by weight of the mixture comprises dicarboxylic aci.d of not more than 9
carbon atoms in a straight chain is included as an anti-cracking agent.
:[n another aspect, the invention provides a process for preparing a
detergent bar as defined above, the process comprising addi.ng the anti-cracking
agent to a soap mix in at least one of a crutcher and amalgamator.
DESCRIPTION OF INVENTION
This invention provides soap compositions, and particularly soap bars
of improved and outstanding resistance to wet cracking by the incorporation into
the soap at any stage of ma~ing and/or processing, but preferably in the
amalgamator, of about 1 to 5% by weight, preferably 2 to 4% and more preferably
2 to 3.5% of a mixture of at least two polycarboxylic acids or anhydrides of
4 to 20 carbon atoms; at least about 20% by weight of the mixture, preferably
at least about 30% by weight of the mixture and more preferably about 50% of
the mi.xture comprises a dicarboxylic acid of no more than nine carbon atoms in
a straight chain. Illustrative dicarboxylic acids are succinic acid, glutaric,
adiptic acid, pimelic, suberic and azelaic acid and their anhydrides. As the
polycarboxylic acid component in addition to the foregoing one may use any C4
to C20 dicarboxylic, tricarboxylic, tetracarboxylic or pentacarboxylic acid,
but a dicarboxylic of C4 to C20 or a tricarboxylic acid is preferred.
Substituted acids are also operable such as citric, malic and tartaric acids.
Unsaturated acids as well as the aforementioned saturated acids may be used.
Within the parameters of C4 to C20 and the requirement for an acid of no more
than C9 in a chain, one may use, as illustrative of the unsaturated acids~
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fumaric, maleic, and the higher acids such as hexenedioic, heptenedioic and
the like.
The soap compositions contemplated herein are the conventional salts
of fatty acids of C8 to C20 and pre~erably C12 to C18. The salts may be
alkali metal or alkaline earth salts, wherein the cation, illustratively may
be sodium, potassium, lithium, calcium, magnesium, etc.. The sodium salts are
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preferred. Particular examples of fatty acids are those derived from natural
fats and oils and include the coconut and tallow fatty acids, fatty acids from
olive oil, palm kernel oil, cotton seed oil, peanut oil and tall oil. The
fatty acids may also be derived synthetically by paraffin oxidation, oxo-
synthesis or the like.
The soap composition of this invention may also include the usual
additive and adjuncts such as super-fatting agents, perfumes, coloring matter,
anti-oxidants, proteins, binding agents, sequestrants, foam boosters, optical
brighteners, anti-bacterial agents, inorganic salts as fillers and builders
and the like. Generally, such additives are used in conventional amounts
(e.g. 0.1% to about 50%). In addition to the soap as the wash-active sub-
stance, other synthetic detergents may be used in admixture with the soap.
These include paraffin sulfonates (C8 to C20~, olefin sulfonates (C8 to C20),
sulfosuccinates, alkyl sulfonates (C8 to C20), alkyl sulfates (C~ to C20),
ethoxylated (1 to 100 moles ethylene oxide) alkyl sulfates ~C8 to C20), alkyl
aryl sulfonates, iso~hionates (alkyl of C8 to C18), taurides (C8 to Cl~ alkyl),
nonionics and the like. In general, such other detergents are employed to
constitute from about 1% to about 75% by weight and preferably about 5 to 50%
by weight of the total detergent (including soap) present.
The following examples will serve to illustrate the present inven-
tion without being deemed limitative thereof; parts are by weight unless
otherwise indicated.
EXAMPLE 1
To 92.1 parts of soap chips at 13% moisture level (soap is a 17/83
coco/tallow soap) in a conventional amalgamator are added 1.0 part of azelaic
acid, 1.0 part sebacic acid, 0.8 parts titanium dioxide and 1.0 part perfume.
Soap bars (about 100 grams each) are formed in a conventional manner by extru-
sion and pressing. The bars are tested for wet cracking. The test involves
immersing the bar in water at 75F for 4 hours, removing~ hanging to dry and
evaluating after about 24 hours. The severity of the cracks are determined on
a scale of 0 to 5; very tiny cracks being assigned a severity value o~ 1,
larger cracks 2 to 4 depending on size and when the bar is badly cracked or
split a value of 5 is given. The number of cracks is also counted and the
product of severity and number of cracks is the cracking rating. When the
rating is 0, obviously the bar has no cracks of any kind at all. The bars
(average of 31 bars) have a cracking rating of < 9. This compares with a rat-
ing of 51 obtained using 3.5% of coco acids in the same procedure and a ratingof 40 using 2% sebacic; a rating of 37 using 2% citric acid and an average
value of about 60 using no free acids.
F.XAMPLE 2
When Example 2 is repeated with 1.5% of each dibasic acid, the
cracking rating is 2.
EXAMPLE 3
Example 1 is repeated except the acids are first dispersed in a
liquid carrier comprising about 40% water, 30% glycerin and 20% propylene
glycol. qual parts of acid and carrier are used. Excellent results are ob-
tained.
XAMPL~ 4
Example 1 is again repeated using 1.2 parts each of adipic andazelaic acids. A superior cracking rating is obtained.
