Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Matrices
Reexamination Certificate
1998-08-14
2002-09-10
Webman, Edward J. (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Matrices
C424S070160, C424SDIG002, C514S844000, C514S846000, C514S944000
Reexamination Certificate
active
06447803
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a thickener-rheology modifier system for personal care compositions and particularly for hair and skin care compositions comprising the combination of a hydrophobically modified alkali-soluble thickener and a polysaccharide hydrocolloid or gum-type thickener or polyalkylene glycol, preferably with a surfactant and more preferably with boric acid.
Polymeric water-soluble thickening agents are widely known and used in many aqueous systems including coating applications, household and personal care products. Carboxyl-containing copolymers produced by the addition or free-radical polymerization of ethylenically unsaturated monomers and that swell or solubilize to thicken aqueous media on neutralization are commonly referred to as alkali-swellable or alkali-soluble thickeners. Hydrophobically modified or associative alkali-soluble thickeners have been developed to provide enhanced thickening properties. A description of alkali-soluble thickeners (AST) and associative AST's can be found in an American Chemical Society article by G. D. Shay entitled “Alkali-Swellable and Alkali-Soluble Thickener Technology”, 1989, pp. 457-493.
While different thickeners including associative alkali-soluble thickeners have been disclosed in various applications, there still is the desire to find a system which provides suitable thickening as well as other rheological properties needed for personal care applications. This invention provides a thickener-rheology modifier system which significantly improves the thickening properties of alkali-swellable thickeners and also improves rheology characteristics of gel textures and emulsions from brittle/cuttable to more flowable, shear thinning and makes the products aesthetically acceptable for personal care use.
SUMMARY OF THE INVENTION
Now it has been found that a selected thickener-rheology modifier system comprising the combination of a hydrophobically, modified alkali-soluble thickener and a polysaccharide hydrocolloid or gum or polyalkylene glycol, preferably with a surfactant and more preferably with boric acid is especially useful in personal care compositions such as hair care and skin care compositions. These compositions which contain the thickener-rheology modifier system as described herein, provide the combination of improved thickening properties for alkali-swellable thickeners as well as improved rheology properties such as altered gel textures from brittle/cuttable to more flowable, shear thinning.
More particularly, this invention relates to a thickener-rheology modifier system for use in hair care and skin care compositions comprising:
a) a hydrophobically modified, alkali-soluble copolymer thickener comprising an aqueous emulsion copolymer of:
i) from about 5 to 70 weight percent of &agr;, &bgr;, ethylenically unsaturated carboxylic acid monomer of the formula:
where R is H and R
1
is H, C
1
-C
4
alkyl, or —CH
2
COOX; R is —COOX and R
1
is H or —CH
2
COOX; and R is CH
3
and R
1
is H, C
1
-C
4
alkyl or —CH
2
COOX; and X is H or C
1
-C
4
alkyl;
ii) from about 10 to 90 weight percent of a nonionic, copolymerizable, &agr;, &bgr;, ethylenically unsaturated monomer of the formula:
CH
2
═CYZ
where Y is H or CH
3
and Z is
where R is C
1
to C
4
alkyl; and
iii) from about 1 to 30 weight percent of a hydrophobically modified, &agr;, &bgr;, ethylenically unsaturated carboxylic acid monomer of the formula:
where R is an alkyl group of 6 to 22 carbon atoms or an alkaryl of 8 to 22 carbon atom, x is an average number of from about 6 to 200, y is an average number of from about 0 to 50 and A is residue of an unsaturated carboxylic acid having the formula:
were R′ is H, —COOH or CH
3
and R″ is H, CH
3
, —COOH or —CH
2
COOH; and
b) a polysaccharide hydrocolloid or gum or polyalkylene glycol.
Preferably the thickener-rheology modifier system will contain a surfactant and more preferably will contain boric acid.
DETAILED DESCRIPTION OF THE INVENTION
The thickener-rheology modifier system of this invention includes a hydrophobically modified alkali-soluble thickener (associative AST) which is an aqueous emulsion copolymer of i) an &agr;, &bgr; ethylenically unsaturated carboxylic acid monomer; ii) a nonionic, copolymerizable &agr;, &bgr; ethylenically unsaturated monomer and iii) a hydrophobically modified &agr;, &bgr; ethylenically unsaturated carboxylic acid monomer.
The alkali soluble polymer thickener will comprise about 5 to 70 weight percent of an &agr;, &bgr; ehtylenically unsaturated carboxylic acid monomer of the formula:
where R is H and R
1
is H, C
1
-C
4
alkyl, or —CH
2
COOX; R is —COOX and R
1
is H or —CH
2
COOX; and R is CH
3
and R
1
is H, C
1
-C
4
alkyl or —CH
2
COOX; and X is H is C
1
-C
4
alkyl.
Examples of these acid monomers include acrylic, methacrylic, crotonic, acyloxypropionic, maleic, fumaric, itaconic, aconitic and half or mono esters of the dibasic or tribasic acids such as the monobutyl ester of maleic acid can also be used to advantage. Acrylic and methacrylic acid are preferred acid monomers. The preferred amount of these acid monomers is from about 30 to 50 percent by weight.
The nonionic, copolymerizable, &agr;, &bgr;, ethylenically unsaturated monomer component of the alkali-soluble thickener has the formula:
CH
2
═CYZ
where Y is H or CH
3
and Z is
where R is C
1
to C
4
alkyl.
Examples of these nonionic monomers are the C
1
-C
4
alkyl acrylates and methacrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, and ethyl methacrylate. The amount of nonionic monomer in the alkali-soluble copolymer will be from about 10 to 90 weight percent and preferably from about 30 to 70 weight percent.
The third monomer component of the alkali-soluble copolymer is a hydrophobically modified &agr;, &bgr; ethylenically unsaturated carboxylic acid monomer of the formula:
where R is an alkyl group of 6 to 22 carbon atoms or an alkaryl group of 8 to 22 carbon atoms, x is an average number of from about 6 to 100, y is an average number of from about 0 to 50 and A is the residue of an unsaturated carboxylic acid having the formula:
where R′ is H, —COOH or CH
3
and R″ is H, CH
3
, —COOH or —CH
2
COOH.
Preferably R in the hydrophobically modified carboxylic acid monomer will contain from 10 to 20 carbon atoms, x is an average number of 10 to 60 and y is an average number of 0 to 30 and A is acrylic, methacrylic or itaconic acid. The amount of the hydrophobically modified carboxylic acid monomer in the alkali-soluble copolymer will be from about 1 to 30 weight percent and preferably 5 to 20 weight percent.
The hydrophobically modified carboxylic acid monomers used in this invention and described above can be prepared by the conventional catalyzed esterification reaction of an alcohol with acid. Other known alternate esterification methods include alcoholysis and transesterification such as disclosed in U.S. Pat. No. 4,384,096.
The alkali-soluble copolymer thickener may be prepared by conventional emulsion polymerization techniques using appropriate emulsifiers for emulsifying the monomers and maintaining the polymer obtained in a stable-dispersed condition. A typical technique is described in U.S. Pat. No. 4,616,074 where the polymerization is carried out in continuous, semi-continuous or batch fashion with the polymerization reaction initiated at 40 to 90° C. A thermal decomposition initiator such as ammonium persulfate or potassium persulfate is used or at lower temperatures a redox initiator such as t-butyl hydroperoxide/bisulfite is used. An anionic emulsifier is normally included in the reaction medium at a concentration of about 1 to 3% to maintain a stable aqueous dispersion. Suitable emulsifiers include sodium lauryl sulfate, sodium dodecylbenzene sulfonate as well as other ammonium and alkali metal alkyl aryl sulfonates and alkyl sulfates. The polymerization is carried out at a pH below about 5.0 to maintain the insolubility of the copolymer in continuous water phase. The copolymer dispersions have relatively low
Babenko Tamara
Cottrell Ian W.
Pluyer Johan G. L.
Sorrentino Paul M.
Kaiser, Esq. Karen G.
National Starch and Chemical Investment Holding Corporation
Webman Edward J.
LandOfFree
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