Accelerator system for synthetic polyisoprene latex
View Patent ↗The invention pertains to an accelerator system, such as an accelerator system for synthetic polyisoprene latex. The accelerator system comprises dithiocarbamate and thiourea and can produce synthetic polyisoprene films having a tensile strength of about 3,000 psi to about 5,000 psi at low curing temperatures. The invention also pertains to a method for curing synthetic polyisoprene latex.
1. A composition comprising synthetic polyisoprene latex and an accelerator system having about 0.5 phr to about 4.0 phr dithiocarbamate and greater than 0.2 phr to about 4.0 phr thiourea wherein the composition does not contain tetramethyithiuram disulfide or diphenylguanidine and a polyisoprene film formed from heating and curing the composition has a tensile strength of about 3,000 psi to about 5,000 psi.
2. The composition of claim 1 wherein the amount of dithiocarbamate is from about 0.5 phr to about 1.5 phr.
3. The composition of claim 1 wherein the dithiocarbamate is selected from the group consisting of sodium dithiocarbamate, zinc dithiocarbamate and combinations thereof.
4. The composition of claim 3 wherein the zinc dithiocarbamate is selected from the group consisting of zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibenzyldithiocarbamate and combinations thereof.
5. The composition of claim 1 further comprising thiazole.
6. The composition of claim 5 wherein the thiazole is selected from the group consisting of zinc 2-mercaptobenzothiazole, sodium 2-mercaptobenzothiazole, or combinations thereof.
7. The composition of claim 1 wherein the thiourea is 1,3 dibutyl thiourea.
8. The composition of claim 1 wherein the amount of thiourea is about 0.5 phr to about 4 phr.
9. The composition of claim 1 wherein the amount of thiourea is about 0.5 phr to about 1.5 phr.
10. A method for curing synthetic polyisoprene latex comprising the steps of forming a film from a composition comprising synthetic polyisoprene latex and an accelerator system having about 0.5 phr to about 4.0 phr dithiocarbamate and greater than 0.2 phr to about 4.0 phr thiourea wherein the accelerator system does not contain tetramethyithiuram disulfide or diphenylguanidine and heating the film at a temperature of about 90° C. to about 140° C. for up to about 30 minutes wherein the synthetic polyisoprene latex cured film has a tensile strength of about 3,000 psi to about 5,000 psi.
11. The method of claim 10 wherein the dithiocarbamate is selected from the group consisting of sodium dithiocarbamate, zinc dithiocarbamate and combinations thereof.
12. The method of claim 11 wherein the zinc diothiocarbamate is selected from the group consisting of zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibenzyldithiocarbamate and combinations thereof.
13. The method of claim 10 wherein the accelerator system further comprises thiazole.
14. A latex glove comprising synthetic polyisoprene latex cured in accordance with the method of claim 10 .
15. The method of claim 10 wherein the amount of dithiocarbamate is about 0.5 phr to about 1.5 phr.
16. The method of claim 10 wherein the amount of thiourea is about 0.5 phr to about 4 phr.
17. The method of claim 16 wherein the amount of thiourea is about 0.5 phr to about 1.5 phr.
18. A method for curing synthetic polyisoprene latex comprising the steps of forming a film from a composition comprising synthetic polyisoprene latex and an accelerator system having dithiocarbamate and 1,3 dibutyl thiourea wherein the accelerator system does not contain tetramethyithiuram disulfide or diphenylguanidine and heating the film at a temperature of about 90° C. to about 140° C. for up to about 30 minutes wherein the synthetic polyisoprene latex cured film has a tensile strength of about 3,000 psi to about 5,000 psi.