Producing polychloroprene latices
View Patent ↗The novel process provides latices of homo- and copolymers of chloroprene and of one or more further copolymerizable monomers at a higher reaction rate and hence in an improved space-time yield. The latices obtained have a high gel content, distinctly lower levels of by-products, in particular of chloroprene dimer, than prior art products, and are useful, if appropriate in concentrated form, for a wide variety of applications.
1. A process for producing a latex of homo- or copolymers of chloroprene and if appropriate one or more further copolymerizable unsaturated monomers by emulsion polymerization, comprising, proceeding from a starting temperature T s , raising the polymerization temperature during the emulsion polymerization
a) by at least 3° C. above the starting temperature T s up to a conversion of 50% and subsequently
b) increasing the polymerization temperature of part a) by at least another 3° C. up to a conversion of 90%.
2. The process according to claim 1 , wherein the starting temperature T s and the polymerization temperature range from 0° C. to 70° C.
3. The process according to claim 1 , wherein the starting temperature T s and the polymerization temperature range from 10° C. to 60° C.
4. The process according to claim 1 , wherein proceeding from a starting temperature T s , the polymerization temperature is raised during the emulsion polymerization
c) by at least 5° C. above the starting temperature T s up to a conversion of 50% and subsequently
d) increasing the polymerization temperature of part a) by at least 3° C. and at least 8° C. above the starting temperature T s up to a conversion of 90%.
5. The process according to claim 1 , wherein the polymerization temperature is raised in stages or continuously.
6. The process according to claim 1 , wherein as well as chloroprene, one or more further copolymerizable unsaturated monomers are used which are monomers having 3 to 12 carbon atoms and 1 or 2 copolymerizable C═C double bonds per molecule.
7. The process according to claim 6 , wherein as well as chloroprene 2,3-dichlorobutadiene or 1-chlorobutadiene is used as further copolymerizable monomer.
8. The process according to claim 1 , wherein the process is carried out either batchwise or continuously.
9. A process for producing a latex of homo- or copolymers of chloroprene and if appropriate one or more further copolymerizable unsaturated monomers by emulsion polymerization, comprising, proceeding from a starting temperature T s , raising the polymerization temperature during the emulsion polymerization
(a) by at least 5° C. above the starting temperature T s up to a conversion of 50% and subsequently
(b) increasing the polymerization temperature of part a) by at least another 1° C. up to a conversion of 90%.