Patent ID: 11965046
Assignee: SYNTHOMER SDN. BHD.
Field: Other special machines (Mechanical engineering)
Classification: CPC C  B | IPC B  C

Claim 0:
1. A method for making dip-molded articles by:
a) immersing a mold having a desired shape of a final article in a coagulant bath comprising a solution of a metal salt;
b) removing the mold from the coagulant bath and optionally drying the mold;
c) immersing the mold as treated in step a) and b) in a compounded latex composition suitable for the production of dip-molded articles comprising:
a polymer latex for dip-molding applications obtained by free-radical emulsion polymerization of a mixture of ethylenically unsaturated monomers selected from the group consisting of:
15 to 99 wt.-% of conjugated dienes;
1 to 80 wt.-% of monomers selected from ethylenically unsaturated nitrile compounds;
0 to 40 wt.-% of vinyl aromatic monomers;
0 to 25 wt.-% of C1 to C8 alkyl (meth)acrylate;
0 to 10 wt.-% of ethylenically unsaturated acids; and
0 to 10 wt.-% of ethylenically unsaturated compounds bearing silane, sulfonate, sulfonic acid, amide and/or N-methylolamide groups, the weight percentages being based on the total monomers employed in the emulsion polymerization, the mixture comprising the at least one conjugated diene and the at least one ethylenically unsaturated nitrile compound in an aqueous medium in presence of seed latex particles having a glass transition temperature (mid point temperature Tmg) measured by DSC according to ASTM D3418-03 of −40° C. to 50° C., wherein the seed latex particles do not contain structural units derived from ethylenically unsaturated nitrile compounds, wherein a z-average particle size measured with a Malvern zetasizer nano S (ZEN 1600) using dynamic light scattering of the seed latex particles is 10 to 80 nm, and wherein the polymer latex has a maximum electrolyte stability determined as critical coagulation concentration of less than 30 mmol/l calcium chloride, wherein the seed latex particles comprise structural units derived from 80 to 99.95 wt.-% of alkyl esters of ethylenically unsaturated acids, and 0.05 to 10 wt.-% of ethylenically unsaturated acids, based on the total weight of monomers constituting the seed particles; and
optionally adjuvants selected from sulfur, accelerators for sulfur vulcanization, crosslinkers, polyvalent cations and combinations thereof;

d) coagulating a latex film on the surface of the mold;
e) removing the latex-coated mold from the compounded latex composition and optionally immersing the latex-coated mold in a water bath;
f) optionally drying the latex-coated mold;
g) heat treating the latex-coated mold obtained from step e) or f) at a temperature of 80° C. to 180° C.; and
h) removing the latex article from the mold, wherein, after completion of steps a) through g), the latex article has an elongation break of at least 500%.