Claims
- 1. A suspension polymerization process of making the fixative tetrapolymer consisting essentially of (1) vinyl acetate, (2) vinyl neodecanoate or vinyl neononanoate, (3) monoisobutyl maleate and (4) N-t-butyl acrylamide, N-t-octyl acrylamide or isobornyl (meth)acrylate, in which said tetrapolymer has a molar ratio of 10:10:15:1 to 26:1:15:1, in the form of microspheres, which comprises polymerizing the monomer components in the presence of a dual initiator system which comprises a first low temperature initiator and a second, longer half-life, high temperature initiator.
- 2. A process according to claim 1 wherein the first initiator starts the polymerization at about 55-65.degree. C. and the second initiat or completes the polymerization at about 65-90.degree. C.
- 3. A process according to claim 1 wherein azeotropic distillation is used to remove residual monomers and other volatile substances from the reaction product.
- 4. A process according to claim 1 in which both initiators are present in the reaction mixture before polymerization of said monomers.
- 5. A process according to claim 1 in which said microspheres are beads having an average diameter of about 0.05 to 2.5 mm.
- 6. A process according to claim 1 in which the concentration of total monomers in the suspension medium is about 10 to 50 wt. %.
- 7. A process according to claim 1 in which about 0.05 to 5.0 wt. % of initiators, based on total monomers, is used in the polymerization.
CROSS-REFERENCE TO RELATED PATENT APPLICATION
This application is a continuation-in-part of copending U.S. patent application, Ser. No. 08/857,954, filed May 16, 1997, new U.S. Pat. No. 5,830,439, and assigned to the same assignee as herein.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4129703 |
Kamath et al. |
Dec 1978 |
|
5275811 |
Chuang et al. |
Jan 1994 |
|
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
857954 |
May 1997 |
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