Method and colorant for the coloring of rubber

Abstract

The present invention provides a method for coloring a rubber substrate with a latex-based colorant comprising the steps of providing a latex-based colorant that includes an elastomeric latex-based binder and a pigment system and mixing the latex-based colorant with the rubber substrate. Optionally, the latex-based colorant further comprises a surfactant system, a thickener, a defoamer, and an antioxidant. The present invention further provides a colored rubber and a latex-based colorant for coloring rubber.

What is claimed:  
     
         1 . A method of coloring a rubber substrate, comprising the steps of: 
 providing a latex-based colorant comprising 5-50 percent by weight latex-based binder, 10-70 percent by weight a pigment system comprising an organic pigment dispersion and opacifer, and 0-85 percent by weight water; and    mixing said latex-based colorant with said rubber substrate.    
     
     
         2 . The method of  claim 1  wherein said latex-based colorant comprises 10-20 percent by weight latex-based binder, 30-55 percent by weight said pigment, and 25-60 percent by weight water.  
     
     
         3 . The method of  claim 1  further comprising the step of vulcanizing the rubber during the mixing of said colorant and said rubber substrate.  
     
     
         4 . The method of  claim 3  wherein said rubber is vulcanized with a vulcanization agent, a cure activator, and an accelerator.  
     
     
         5 . The method of  claim 4  wherein said vulcanization agent is a water based dispersion of sulfur, said cure activator is a water based dispersion of zinc oxide, and said accelerator is selected from the group consisting of thiuram, dithiocarbonate, xanthate, mercapto thiazole, mercapto sulfonamide, thiourea, and guanidine.  
     
     
         6 . The method of  claim 1  wherein said rubber is black.  
     
     
         7 . The method of  claim 1  wherein said latex binder comprises an elastomeric latex selected from the group consisting of natural rubber, synthetic rubber, or a mixture thereof, wherein said elastomeric latex forms lattices, or colloidal dispersions of polymeric material, in a water-based system and has a solids content between 25-75%.  
     
     
         8 . The method of  claim 7  wherein said synthetic rubber is selected from the group consisting of styrene butadiene rubber, nitrile rubber, butyl rubber, polychloroprene rubber, and ethylene-propylene rubber.  
     
     
         9 . The method of  claim 1  wherein said water based colorant further comprises a surfactant system, a defoamer, an antioxidant, and a thickener.  
     
     
         10 . The method of  claim 11  wherein said surfactant system is selected from the group consisting of non-ionic, anionic, and cationic surfactants, and mixtures thereof; said defoamer comprises a mixture of hydrophobic solids and polysiloxanes; said antioxidant is selected from the group consisting of is N-N′ Di(2-octyl)-p-phenylene diamine, diphenyl-p-phenylendedeiamine, octylated diphenulamine, dioctylated diphenylamine, styrenated phenol, hindered phenol, and mixtures thereof; and said thickener is selected from the group consisting of a gum, starch, cellulose polymer, mineral, alginate, and mixtures thereof.  
     
     
         11 . The method of  claim 1  wherein said pigment system comprises titanium oxide and an organic pigment dispersion.  
     
     
         12 . The method of  claim 11  wherein said pigment system comprises titanium dioxide and a water dispersion of an organic pigment between a 3:1 and 2:1 ratio, respectively.  
     
     
         13 . The method of  claim 1  wherein said rubber substrate is selected from the group consisting of crumb rubber, natural rubber, styrene butadiene rubber, nitrile rubber, butyl rubber, polychloroprene rubber, and ethylene-propylene rubber.  
     
     
         14 . The method of  claim 1  wherein said rubber substrate is crumb rubber.  
     
     
         15 . A latex-based colorant for coloring a rubber substrate comprising a latex binder and a pigment system.  
     
     
         16 . The latex-based colorant of  claim 15  wherein said latex binder comprises an elastomeric latex selected from the group consisting of natural rubber, synthetic rubber, or a mixture thereof, wherein said elastomeric latex forms lattices, or colloidal dispersions of polymeric material, in a water-based system and has a solids content between 25-75%.  
     
     
         17 . The latex-based colorant of  claim 16  wherein said synthetic rubber is selected from the group consisting of styrene butadiene rubber, nitrile rubber, butyl rubber, polychloroprene rubber, and ethylene-propylene rubber.  
     
     
         18 . The latex-based colorant of  claim 16  wherein said water-based colorant further comprises a surfactant system, a defoamer, an antioxidant, and a thickener.  
     
     
         19 . The latex-based colorant of  claim 18  wherein said surfactant system surfactant system is selected from the group consisting of non-ionic, anionic, and cationic surfactants, and mixtures thereof, said defoamer is a mixture of hydrophobic solids and polysiloxanes; said antioxidant is selected from the group consisting of is N-N′ Di(2-octyl)-p-phenylene diamine, diphenyl-p-phenylendedeiamine, octylated diphenulamine, dioctylated diphenylamine, styrenated phenol, hindered phenol, and mixtures thereof; and said thickener is selected from the group consisting of a gum, starch, cellulose polymer, mineral, alginate, and mixtures thereof.  
     
     
         20 . The latex-based colorant of  claim 16  wherein said pigment comprises titanium oxide and an organic pigment dispersion.  
     
     
         21  Colored rubber comprising a rubber substrate and a colored latex coating in contact with said rubber substrate.  
     
     
         22 . The colored rubber of  claim 21  wherein said colored latex coating comprises a pigment system and latex binder.  
     
     
         23 . The colored rubber of  claim 22  wherein said pigment system comprises an opacifer and an organic pigment dispersion.  
     
     
         24 . The colored rubber of  claim 21  wherein said rubber substrate is selected from the group consisting of natural rubber, crumb rubber, styrene butadiene rubber, nitrile rubber, butyl rubber, polychloroprene rubber, and ethylene-propylene rubber.  
     
     
         25 . The colored rubber of  claim 21  wherein said rubber substrate is crumb rubber.