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This invention is directed to an improvement in the method of making siloxane-based polyamides described in a prior copending application, U.S. Ser. No. 08/904,709, filed Aug. 1, 1997, and entitled xe2x80x9cCosmetic Composition Containing Siloxane-Based Polyamides as Thickening Agentsxe2x80x9d, hereafter referred to as the ""709 application.
The present invention relates to a novel method of making siloxane-based polyamides.
There is a growing demand in the personal care arena for polymeric materials capable of thickening dimethylcyclosiloxanes in order to modify product viscosity in various market niche hair, skin, cosmetic, and underarm, applications.
The ""709 application is directed to one type of a process for preparing siloxane-based polyamides. The process according to the ""709 application involves many steps, and this results in cost prohibitive products which are difficult to produce in commercial quantity.
For example, in the ""709 application process, a dimethyl hydride endblocked polydimethylsiloxane is first prepared containing the appropriate number of siloxane units to achieve a desired value of DP. The carboxylic acid group of undecylenic acid is then protected through reaction with hexamethyldisilazane. The dimethyl hydride endblocked polydimethylsiloxane and the protected undecylenic acid are reacted to produce a siloxane diacid, i.e., a carboxydecyl terminated polydimethylsiloxane. This reaction is accomplished in the presence of a platinum catalyst, and the product is washed with methanol to remove the trimethylsilyl protecting group from the protected siloxane diacid. The siloxane diacid is then reacted with an organic diamine to produce a siloxane-based polyamide.
Accordingly, a new process has been discovered herein that eliminates many of the otherwise costly steps involved in the process according to the ""709 application.
The new process basically involves the addition of an olefinic acid with an organic diamine to produce an organic diamide. One the olefinic acid and the organic diamine are fully reacted, an xe2x89xa1SiH endblocked polysiloxane is added in the presence of a platinum catalyst, to produce a siloxane-based polyamide via hydrosilylation. The resulting polymeric product is in the form of a high molecular weight thermoplastic polymer. The benefits of this process is that it allows for the production of a cost effective manufactured product in commercial quantity.
This invention relates to a method of forming a siloxane-based polyamides which are useful as thickening agents to formulate a wide variety of cosmetic compositions. The polyamides of this invention are multiples of a unit represented by the following Formula A: 
where:
(1) The degree of polymerization (DP) is 1-700, preferably 10-500, and more preferably 15-45. DP represents an average value for degree of polymerization of the siloxane units in the polymer with greater or lesser DP values centered around the indicated DP value.
(2) n is 1-500, particularly 1-100, and more particularly 4-25.
(3) X is a linear or branched chain alkylene having 1-30 carbons, particularly 3-10 carbons, and more particularly 10 carbons.
(4) Y is a linear or branched chain alkylene having 1-40 carbons, particularly 1-20 carbons, more particularly 2-6 carbons, and especially 6 carbons wherein
(a) The alkylene group may optionally and additionally contain in the alkylene portion at least one of (i) 1-3 amide linkages; (ii) a C5 or C6 cycloalkane; or (iii) phenylene, optionally substituted by 1-3 members which are independently C1-C3 alkyls; and
(b) the alkylene group itself may optionally be substituted by at least one of (i) hydroxy; (ii) a C3-C8 cycloalkane; (iii) 1-3 members which are independently C1-C3 alkyls; phenyl, optionally substituted by 1-3 members which are independently C1-C3 alkyls; (iv) a C1-C3 alkyl hydroxy; or (v) a C1-C6 alkyl amine; and
(c) Y can be Z where Z is T(R20)(R21)(R22) where R20, R21 and R22 are each independently linear or branched C1-C 10 alkylenes; and T is CR in which R is hydrogen, the group defined for R1-R4, or a trivalent atom such as N, P and Al.
(5) Each of R1-R4 (collectively xe2x80x9cRxe2x80x9d) is independently methyl, ethyl, propyl, isopropyl, a siloxane chain, or phenyl, wherein the phenyl may optionally be substituted by 1-3 members which are methyl or ethyl. More particularly, R1-R4 are methyl or ethyl, especially methyl.
(6) X, Y, DP, and R1-R4 may be the same or different for each polyamide unit.
By xe2x80x9csiloxane chainxe2x80x9d is meant a group of units such as: 
where R30 and R31 are each independently organic moieties; and each R30 and R31 are connected to silicon by a carbon-silicon bond.
The carbon numbers in the alkylene chain do not include the carbons in the extra segments or substitutions. Also, the polyamides must have a siloxane portion in the backbone and optionally may have a siloxane portion in a pendant or branched portion.
If repeated with no variations in the defined variables, Formula A is representative of a linear homopolymer. Variations of the invention include: (1) polyamides in which multiple values of DP, and of units X, Y, and R1-R4 occur in one polymeric molecule, and wherein the sequencing of these units may be alternating, random or block; (2) polyamides in which an organic triamine or higher amine such as tris(2-aminoethyl)amine replaces the organic diamine in part, to produce a branched or crosslinked molecule; and (3) physical blends of any of (1) and (2) and/or linear homopolymers.
These and other features of the invention will become apparent from a consideration of the detailed description.
Not applicable.