Low viscosity high solids copolymer
View Patent ↗A copolymer is made by feeding one or more added olefinic monomers into a reaction vessel containing a non-homopolymerizable olefinic monomer heated to a temperature of at least about 100° C. The process may be performed in a batch or continuous fashion, may use an unpressurized reactor, may be performed without added solvent, and may form a copolymer whose number average molecular weight is less than about 4,000 amu and whose polydispersity is less than about 3.
1. A process for making a copolymer, which process comprises:
a) providing a reaction vessel containing a non-homopolymerizable olefinic monomer heated to a temperature of at least 100° C.; and
b) feeding one or more added olefinic monomers into the non-homopolymerizable olefinic monomer in the presence of a free radical initiator to form a copolymer of the added olefinic and non-homopolymerizable olefinic monomers.
2. A process according to claim 1 wherein the copolymer is formed in an unpressurized reactor.
3. A process according to claim 1 wherein the non-homopolymerizable olefinic monomer has the formula:
or is an anhydride thereof, wherein each X moiety independently is hydrogen, halogen, or an organic group and at least two X moieties are selected from R 1 , COOR 2 , and Ar, wherein R 1 is an organic group; R 2 is hydrogen, halogen, or an organic group; and Ar is an aromatic group.
4. A process according to claim 1 wherein the non-homopolymerizable olefinic monomer comprises fumaric acid, maleic acid, maleic anhydride, trans-beta-methylstyrene, alpha-ethylstyrene, diethyl fumarate, diethyl maleate, cis-stilbene or trans-stilbene.
5. A process according to claim 1 wherein the non-homopolymerizable olefinic monomer comprises alpha-methylstyrene.
6. A process according to claim 1 wherein the non-homopolymerizable olefinic monomer consists essentially of alpha-methylstyrene.
7. A process according to claim 1 wherein the added olefinic monomer comprises a homopolymerizable (meth)acrylate, vinyl, vinyl ether, alkene or mixture thereof.
8. A process according to claim 1 wherein the added olefinic monomer comprises styrene, vinyl toluene, vinyl acetate, (meth)acrylic acid, methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, hydroxyethyl(meth)acrylate, hydroxybutyl(meth)acrylate, hydroxypropyl(meth)acrylate, glycidyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate glycidylether, 2-(acetoacetoxy)ethyl methacrylate, diacetone acrylamide, methylol(meth)acrylamide, acrylonitrile, allyl methacrylate, or mixture thereof.
9. A process according to claim 1 wherein the copolymer is formed at a solids level of at least about 50 wt. % based on the total copolymer weight.
10. A process according to claim 1 wherein the copolymer is formed at a solids level of at least about 70 wt. % based on the total copolymer weight and in the presence of 0 to about 15 wt. % of the reaction mixture of added solvent, based on the weight of monomers employed.
11. A process according to claim 1 wherein the copolymer is an acrylic copolymer.
12. A process according to claim 1 wherein the copolymer is an acrylic polyol.
13. A process according to claim 1 wherein the copolymer has a number average molecular weight less than about 4,000 amu and a polydispersity less than about 3.
14. A process according to claim 1 wherein the copolymer has a polydispersity less than about 2.5.
15. A process according to claim 1 further comprising reacting the copolymer with one or more monomers to impart reactive unsaturation into the copolymer.
16. A process according to claim 1 comprising feeding more than one added olefinic monomer into the non-homopolymerizable olefinic monomer.
17. A process according to claim 1 wherein a complete polymerization reaction occurs and the non-homopolymerizable olefinic monomer is consumed.
18. A process according to claim 1 wherein the reaction vessel in step a) has contents that consist essentially of the non-homopolymerizable olefinic monomer and an optional initiator.
19. A process according to claim 1 wherein copolymerization commences at an initial reaction temperature of at least about 140° C., and the reaction temperature is raised by at least about 10° C. as the non-homopolymerizable olefinic monomer is consumed.
20. A process according to claim 1 wherein steps a) and b) are performed with little or no added solvent.
21. A process according to claim 20 wherein the non-homopolymerizable olefinic monomer serves as a reactive diluent in which the copolymer is formed without an early increase in viscosity as copolymerization proceeds.
22. A process according to claim 20 wherein the non-homopolymerizable olefinic monomer comprises alpha-methylstyrene, copolymerization commences at an initial reaction temperature of at least about 160° C., and the reaction temperature is increased to at least about 200° C. as the alpha-methylstyrene is consumed.
23. A process according to claim 1 wherein the one or more added olefinic monomers are all homopolymerizable monomers.
24. A process according to claim 1 wherein the non-homopolymerizable olefinic monomer represents about 10 to about 40 wt. % of the total copolymer weight and the one or more added olefinic monomers represent about 60 to about 90 wt. % of the total copolymer weight.
25. A process according to claim 1 wherein the copolymer is water soluble or water dispersible.
26. A process according to claim 1 wherein the copolymer is an acrylic polyol.
27. A process according to claim 1 wherein the copolymer has reactive oxirane groups.
28. A process according to claim 1 wherein the copolymer has reactive acidic groups.
29. A process according to claim 1 wherein the copolymer has condensable crosslinkable groups.