Water-based resin composition and articles made therefrom

Abstract

An aqueous elastomer dispersion includes a dispersed phase and an aqueous phase. The dispersed phase includes an elastomer including curable aliphatic conjugated-diene elastomers, such as polyisoprene, and a minor amount of at least one additive. The aqueous phase includes water and other optional components in either a soluble state or a dispersion state. The aqueous elastomer dispersion may be prepared by dissolving an elastomer, such as rubber, and additives in a solvent mixture and then converting the resulting solution into an aqueous emulsion. The aqueous emulsion is concentrated and the solvent is stripped from it to yield a dilute latex. The dilute latex that is obtained is concentrated again. Articles made from the aqueous elastomer dispersion include medical gloves, condoms, probe covers, dental dams, finger cots, catheters and the like.

1 . An aqueous elastomer dispersion, comprising:
 a dispersed phase comprising an elastomer and at least one additive; and   an aqueous phase.   
   
   
       2 . The aqueous elastomer dispersion of  claim 1 , wherein the elastomer is a curable aliphatic conjugated-diene elastomer. 
   
   
       3 . The aqueous elastomer dispersion of  claim 1 , wherein the elastomer is selected from the group consisting of polyisoprene, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymers, styrene block copolymers, and butyl rubber. 
   
   
       4 . The aqueous elastomer dispersion of  claim 1 , wherein the elastomer has a molecular weight of about 100,000 to about 3,000,000. 
   
   
       5 . The aqueous elastomer dispersion of  claim 1 , wherein the at least one additive is selected from the group consisting of sulfur/sulfur donors, peroxide curing/crosslinking agents, accelerators, activators, antioxidants, stabilizers, plasticizers, antiozonants, pigments, fillers, antimicrobial agents, indicators, and additional polymers. 
   
   
       6 . The aqueous elastomer dispersion of  claim 1 , wherein an amount of the at least one additive is about 0.5 to about 49% by weight of total solids of the aqueous elastomer dispersion. 
   
   
       7 . The aqueous elastomer dispersion of  claim 5 , wherein sulfur donors are selected from the group consisting of thiuram polysulfides and xanthogen polysulfides. 
   
   
       8 . The aqueous elastomer dispersion of  claim 5 , wherein peroxide curing/crosslinking agents are selected from the group consisting of dibenzoyl peroxides, dicumyl peroxides and combinations thereof. 
   
   
       9 . The aqueous elastomer dispersion of  claim 5 , wherein accelerators are selected from the group consisting of dithiocarbamates, thiazoles, thiuram sulfides, guanidines, and thioureas. 
   
   
       10 . The aqueous elastomer dispersion of  claim 5 , wherein activators are selected from the group consisting of zinc oxide, magnesium oxide, and lead oxide. 
   
   
       11 . The aqueous elastomer dispersion of  claim 5 , wherein antioxidants are selected from the group consisting of hindered phenols, hindered polyphenolics, hindered phenol/hindered polyphenolics, amines, triazinone derivatives, polyaromatic amines, phenolic antioxidant hydrazides, phenolics, cresols, and styrenated phenols. 
   
   
       12 . The aqueous elastomer dispersion of  claim 5 , wherein stabilizers are selected from the group consisting of including alkalis, surfactants and alkaline caseinate. 
   
   
       13 . The aqueous elastomer dispersion of  claim 5 , wherein the antiozonants are selected from the group consisting of alkyl/aryl p-phenylenediamines, organoclay-antiozonant complexes, functionalized benzotriazoles, triazines, p-phenylenediamines, waxes, polymeric antiozonants, and ozone inert polymers. 
   
   
       14 . The aqueous elastomer dispersion of  claim 5 , wherein antimicrobial agents are selected from the group consisting of water-insoluble organic phenol compounds, inorganic silver compounds, zinc compounds, copper compounds, fatty esters, silicone-ammonium polymers, nitrogen-containing polymers, and hydroxybenzoate-containing polymers. 
   
   
       15 . The aqueous elastomer dispersion of  claim 5 , wherein indicators are selected from the group consisting of moisture indicators, colorants, phthalein dyes, organic salts, transition metals, solvatochromic dyes, microbe indicators, solvatochromlc dyes, acid pH dyes, anthocyanin dyes, blood indicators, acid-base indicators, and chemiluminescents. 
   
   
       16 . The aqueous elastomer dispersion of  claim 5 , wherein the additional polymers are selected from the group consisting of a liquid polyisoprene, a polyisoprene with a molecular weight of between about 20,000-100,000, an isomer or analogue of polyisoprene, a terminal-functionalized derivative of polyisoprene, a copolymer of polyisoprene, polychloroprene, a styrene-butadiene copolymer, acrylonitrile-butadiene copolymers, styrene block copolymers, butyl rubber, and modified forms of these polymers. 
   
   
       17 . The aqueous elastomer dispersion of  claim 16 , wherein the styrene block copolymer is a styrene-isoprene-styrene (SIS) copolymer. 
   
   
       18 . The aqueous elastomer dispersion of  claim 16 , wherein the additional polymer has a range of about 0.5 to about 49% (by weight) of the additional polymer in the dispersed phase. 
   
   
       19 . The aqueous elastomer dispersion of  claim 5 , wherein the vulcanization accelerators are added in amounts ranging from about 0.2 to about 10.0 phr. 
   
   
       20 . The aqueous elastomer dispersion of  claim 1 , wherein the aqueous phase comprises water soluble components. 
   
   
       21 . The aqueous elastomer dispersion of  claim 20 , wherein an amount of water soluble components is not more than 10% by weight of total solids of the aqueous elastomer dispersion. 
   
   
       22 . A manufactured article made from the aqueous elastomer dispersion of  claim 1 . 
   
   
       23 . The manufactured article of  claim 22 , wherein the article is selected from the group consisting of gloves, condoms, probe covers, dental dams, finger cots, and catheters. 
   
   
       24 . A method of preparing an aqueous elastomer dispersion, comprising the steps of:
 preparing an elastomer/additive solution comprising an elastomer, at least one additive, and a solvent system;   emulsifying the elastomer/additive solution to form an emulsion;   concentrating the emulsion to form a concentrated emulsion;   removing substantially all of the solvent system from the concentrated emulsion to form a substantially solvent-free dispersion; and   optionally concentrating the substantially solvent-free dispersion.   
   
   
       25 . The method of  claim 24 , wherein the elastomer is selected from the group consisting of polyisoprene, polychloroprene, styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, styrene block copolymers, and butyl rubber. 
   
   
       26 . The method of  claim 25 , wherein the elastomer has a molecular weight of about 100,000 to about 3,000,000. 
   
   
       27 . The method of  claim 25 , wherein the at least one additive is selected from the group consisting of sulfur/sulfur donors, peroxide curing/crosslinking agents, vulcanization accelerators, vulcanization activators, antioxidants, stabilizers, plasticizers, antiozonants, pigments, fillers, antimicrobial agents, indicators, and additional polymers. 
   
   
       28 . The method of  claim 27 , wherein an amount of the at least one additive is about 0.5-49% by weight of total solids of the aqueous elastomer dispersion. 
   
   
       29 . The method of  claim 24 , wherein the solvent system includes a first solvent and second solvent. 
   
   
       30 . The method of  claim 29 , wherein the elastomer is soluble in the first solvent, and the at least one additive is soluble in the second solvent. 
   
   
       31 . The method of  claim 29 , wherein the first solvent includes one or more solvents, and the second solvent includes one or more solvents. 
   
   
       32 . The method of  claim 24 , wherein the emulsifying step comprises adding an emulsifier. 
   
   
       33 . The method of  claim 32 , wherein the emulsifying step further comprises mixing with a high shear mixer. 
   
   
       34 . The method of  claim 24 , wherein one or both of the concentrating steps comprise adding a creaming agent. 
   
   
       35 . The method of  claim 34 , wherein one or both of the concentrating steps further comprise separating a concentrate and an aqueous solution. 
   
   
       36 . The method of  claim 24 , wherein one or both of the concentrating steps is carried out by centrifuging using a continuous centrifugal separator. 
   
   
       37 . The method of  claim 24 , wherein the removing step comprises evaporating the solvent system from the concentrated solution. 
   
   
       38 . The method of  claim 24 , wherein the removing step comprises heating the concentrated solution to evaporate the solvent system. 
   
   
       39 . The method of  claim 24 , further comprising the step of adjusting the pH of the aqueous elastomer dispersion. 
   
   
       40 . The method of  claim 24 , wherein the total solids content of the aqueous elastomer dispersion is about 45-65% by weight. 
   
   
       41 . The method of  claim 24 , further comprising the step of making an article from the aqueous elastomer dispersion. 
   
   
       42 . The method of  claim 41 , wherein the article is selected from the group consisting of gloves, condoms, probe covers, dental dams, finger cots, and catheters.