Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-03-05
2001-03-06
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S314000, C526S266000, C526S270000, C526S271000
Reexamination Certificate
active
06197908
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to copolymers of maleic anhydride and alkyl vinyl ethers, and more particularly, to high molecular weight, homogeneous, branched copolymers of such monomers, and to a solution process of making these polymers, and then use in denture adhesive compositions and personal care formulations.
2. Description of the Prior Art
Copolymers of maleic anhydride and alkyl vinyl ethers are well known in the art. Often, such polymers are prepared by precipitation polymerization in a solvent having a low chain transfer constant, such as benzene or cyclohexane. For example, high molecular weight, linear copolymers of methyl vinyl ether and maleic anhydride can be prepared by precipitation polymerization in benzene, and drying. Usually such precipitation process can be conducted at only a low solids levels, e.g. 20% solids or less.
Accordingly, it is an object of this invention to provide high molecular weight, homogeneous, branched copolymers of maleic anhydride and alkyl vinyl ethers.
Another object of this invention is to provide a solution polymerization process to prepare such high molecular weight, homogeneous, branched copolymers of maleic anhydride and alkyl vinyl ether monomers, in solvents other than benzene, and at a high solids levels, i.e. greater than 30%.
These and other objects and features of the invention will be made apparent from the following description of the invention.
SUMMARY OF THE INVENTION
What is described herein is a high molecular weight, homogeneous, branched copolymer of maleic anhydride and a C
1
-C
5
alkyl vinyl ether monomer, in which the polymer chains are branched with a branching agent present in an amount of less than 0.5 wt. % of the polymer. Suitable polymers herein include those in which the maleic anhydride component is present in the form of its half-ester or diacid derivatives, having a molecular weight of greater than 100,000, preferably greater than 500,000. These polymers are made as a solution of the polymer at a concentration greater than 30% solids, in a non-benzene solvent such as acetone.
The copolymers of the invention are particularly useful in personal care and oral care compositions, for example, in denture adhesive compositions which include about 30-40% by wt. of the polymer.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, there is provided a high molecular weight homogeneous, branched polymer of maleic anhydride and a C
1
-C
5
alkyl vinyl ether monomer, in which the polymer chains are branched with a branching agent present in an amount of less than 0.5 wt. % of the polymer.
As a feature of the invention, there is provided herein a solution polymerization process of making such copolymers. The process includes polymerizing maleic anhydride and an excess of an alkyl vinyl ether over 1:1 stoichiometry of the monomers, in a non-benzene solvent, in the presence of a branching agent present in an amount of less than 0.5 wt. % of the resultant polymer. A preferred non-benzene solvent is acetone, although other solvents in which the reaction product is soluble are also suitable, such as tetrahydrofuran, N-methyl pyrrolidone and the like.
As another feature of the invention, the process can be carried out at a >30% solids level.
Following polymerization, the resultant polymer can be converted to the half-ester or diacid derivative, if desired.
Suitable branching agents are those having a reactivity about the same as maleic anhydride so that all the branching agent and maleic anhydride are consumed in the presence of excess alkyl vinyl ether.
Suitable branching agents include phenylene and/or alkyl dimaleimides, dimaleic anhydrides and alkyl divinyl ethers.
The molecular weight of the copolymer product of the invention is greater than 100,000, preferably greater than 500,000 and, most preferably, greater than 1,000,000.
A preferred alkyl vinyl ether is methyl vinyl ether.
After completion of polymerization, the excess alkyl vinyl ether can be removed to provide the desired polymer in solution.
The copolymers of the invention are used in personal care and oral care compositions, for example, in denture adhesives which include about 30-40% by wt. of the polymer.
REFERENCES:
patent: 4521551 (1985-06-01), Chang et al.
patent: 5093387 (1992-03-01), Schobel et al.
patent: 5561177 (1996-10-01), Khaledi et al.
Davis William J.
ISP Investments Inc.
Katz Walter
Maue Marilyn J.
Pezzuto Helen L.
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