Latex gloves and articles with geometrically defined surface texture providing enhanced grip and method for in-line processing thereof
Latex articles with geometrically defined surface structure providing enhanced grip characteristics in dry, wet or oily environment; and a method of making same comprising applying a polymeric coagulant coating to a smooth former surface, wherein the coating becomes tacky during drying, applying discrete coagulant particles of selected size, shape and distribution to the tacky coating to attach and protrude from the former surface with the polymeric coagulant coating, dipping the former into an aqueous latex emulsion, wherein the polymeric coagulant coating and the discrete coagulating particles destabilize the latex, thereby developing a latex layer, vulcanizing and stripping the latex article inside out, and dissolving the discrete coagulant particles in water or suitable solvents to reveal the geometrically designed texture with pre-selected size, shape and distribution of impressions providing improved dry, wet and oily surface grip by removal of a fluid boundary layer.
1. A method of making a latex article with a geometrically defined surface texture, which method comprises:
dipping a smooth former into a polymeric coagulant composition comprising a water-soluble polymer, a polyglycol, a surfactant, and a coagulating salt;
drying the polymeric coagulant composition to form a tacky, polymeric coagulant coating;
applying discrete coagulant particles to the tacky, polymeric coagulant coating;
dipping the former into a coagulatable aqueous latex emulsion, and destabilizing the latex emulsion in close proximity to the former, thereby forming a coagulated first latex layer that covers the discrete coagulant particles and external surface of the former;
heating the former to form a first cured latex layer by vulcanization or curing;
stripping and inverting the first cured latex layer to expose the discrete coagulant particles; and
leaching or dissolving the discrete coagulant particles in water or an appropriate solvent;
whereupon the latex article with the geometrically defined surface texture is obtained.
2. The method of claim 1 , wherein the polymeric coagulant coating has a thickness in the range of about 5 to 50 microns.
3. The method of claim 1 , wherein the water-soluble polymer is poly N-vinyl-2-pyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyacrylamide (PAC), copolymers thereof, or derivatives thereof.
4. The method of claim 3 , wherein the water-soluble polymer is present in the polymeric coagulant coating in an amount ranging from about 0.01% to about 10.0%, based on dry weight.
5. The method of claim 4 , wherein the water-soluble polymer is present in the polymeric coagulant coating in an amount ranging from about 0.5% to about 1.5%, based on dry weight.
6. The method of claim 3 , wherein the PAA is an acrylic homopolymer.
7. The method of claim 6 , wherein the acrylic homopolymer is methacrylic acid homopolymer.
8. The method of claim 3 , wherein the copolymer is a copolymer of PVP and 1-methyl-3 -vinyl-imidazolium-methylsulfate.
9. The method of claim 3 , wherein the copolymer is vinylcaprolactam/vinyl pyrrolidone/dimethylaminoethyl methacrylate.
10. The method of claim 1 , wherein the polyglycol is polyethylene glycol.
11. The method of claim 1 , wherein the polyglycol is polyethylene oxide/polypropylene oxide copolymers.
12. The method of claim 1 , wherein the surfactant is an ethoxylated acetylenic diol.
13. The method of claim 1 , wherein the coagulating salt is calcium nitrate or calcium chloride.
14. The method of claim 1 , wherein the discrete coagulant particles range in size from about 5 to 1,800 microns.
15. The method of claim 1 , wherein the discrete coagulant particles are water-soluble and selected from the group consisting of sodium chloride, potassium chloride, calcium nitrate, calcium chloride, aluminum chloride, and aluminum sulfate.
16. The method of claim 1 , wherein the discrete coagulant particles are partially water soluble or water-insoluble and comprise one or more of calcium carbonate, magnesium carbonate, sodium carbonate, and sodium bicarbonate.
17. The method of claim 1 , wherein the coagulatable aqueous latex emulsion is comprises carboxylated acrylonitrile butadiene, non-carboxylated acrylonitrile butadiene, butyl latex, polychloroprene, natural rubber, synthetic polyisoprene, or polyurethane.
18. The method of claim 17 , wherein the coagulatable aqueous latex emulsion further comprises a curative.
19. The method of claim 1 , further comprising:
dipping the former into the aqueous latex emulsion for a second time after the step of heating the former to form the first cured latex layer by vulcanization or curing;
forming a second cured latex layer by vulcanizing or curing; and
wherein the stripping and inverting step includes stripping and inverting the second cured latex layer in combination with the first cured latex layer.
20. The method of claim 1 , further comprising:
dipping the former with the first cured latex layer into a foamed aqueous latex emulsion after the step of heating the former to form the first cured latex layer by vulcanization or curing;
forming a foamed cured latex layer by vulcanizing or curing; and
wherein the stripping and inverting step includes stripping and inverting the foamed cured latex layer in combination with the first cured latex layer.
21. The method of claim 1 , further comprising:
applying an adhesive layer to the first cured latex layer after the step of heating the former to form the first cured latex layer by vulcanization or curing;
air blowing or electro-statically blowing cotton or rayon flock over the adhesive layer, thereby forming a flocked layer;
curing the adhesive layer;
wherein the stripping and inverting step includes stripping and inverting the flocked layer in combination with the first cured latex layer.
22. The method of claim 1 , further comprising:
applying a non-tacky polyurethane adhesive layer to the first cured latex layer at room temperature after the step of heating the former to form the first cured latex layer by vulcanization or curing;
applying a knitted liner comprising cotton, an aramid fiber, a polyethylene fiber, a steel wire, or combinations thereof over the non-tacky polyurethane adhesive layer;
heating the former to melt the non-tacky polyurethane adhesive layer, thereby forming a flexible bond between the first cured latex layer and the knitted liner; and
wherein the stripping and inverting step includes stripping and inverting the knitted liner in combination with the first latex layer.
23. The method of claim 1 , wherein the step of applying discrete coagulant particles to the tacky, polymeric coating is done according to a design that includes details of size, shape, and distribution of the particles on the former.