Substituted alkoxylated phenols and branched sulfates for use in emulsion polymer latexes

Abstract

The present technology generally relates to emulsion polymer latexes, particularly those used in pressure sensitive adhesives, paints and coatings. Surfactant compositions of the present technology for use in forming at least one emulsion polymer latex comprise at least one branched surfactant, at least one sterically bulky surfactant, or a mixture of branched and sterically bulky surfactants. One preferred surfactant composition comprises at least one alkoxylated polyaryl substituted aromatic compound or at least one alkoxylated polyalkyl substituted aromatic compound. Another preferred surfactant composition comprises a mixture of at least one branched-alkyl sulfate and at least one ethoxylated polystyrylphenol. Another preferred surfactant composition comprises at least one sulfated polystyrylphenol.

What is claimed is: 
     
         1 . A process for preparing an emulsion polymer latex comprising:
 a) forming a monomer emulsion comprising
 (i) water, 
 (ii) at least one monomer selected from the group consisting of vinyl aromatic monomers, ester acrylate monomers, ester methacrylate monomers, acrylic acid monomers, and methacrylic acid monomers, wherein the acrylic acid monomer does not exceed 2 parts by weight of the monomers present in the monomer emulsion, and 
 (iii) at least one surfactant selected from the group consisting of tristyrylphenol-based surfactants, ethoxylated tristyrylphenol-based surfactants, branched alkyl sulfate surfactants and mixtures thereof, wherein the surfactant does not contain a reactive moiety; and 
   b) polymerizing the at least one monomer in the presence of an initiator to form the emulsion polymer latex.   
     
     
         2 . The process of  claim 1 , wherein the tristyrylphenol-based surfactant is at least one tristyrylphenol sulfate. 
     
     
         3 . The process of  claim 1 , wherein the ethoxylated tristyrylphenol-based surfactant is at least one ethoxylated tristyrylphenol sulfate. 
     
     
         4 . The process of  claim 3 , wherein the ethoxylated tristyrylphenol sulfate has an ethylene oxide loading ranging from about 0.1 to about 100 moles of ethylene oxide per mole of ethoxylated tristyrylphenol. 
     
     
         5 . The process of  claim 4 , wherein the ethoxylated tristyrylphenol sulfate has an ethylene oxide loading ranging from about 16 to about 40 moles of ethylene oxide per mole of ethoxylated tristyrylphenol. 
     
     
         6 . The process of  claim 1 , wherein the at least one polymerizable surfactant is a mixture of a branched alkyl sulfate surfactant, an ethoxylated tristyrylphenol surfactant and an ethoxylated tristyrylphenol sulfate surfactant. 
     
     
         7 . The process of  claim 1 , wherein the ethoxylated tristyrylphenol-based surfactant is an ethoxylated tristyrylphenol phosphate ester. 
     
     
         8 . The process of  claim 1 , wherein the branched alkyl sulfate surfactant has a degree of branching greater than about 15%. 
     
     
         9 . The process of  claim 1 , wherein the branched alkyl sulfate surfactant has a degree of branching greater than about 20%. 
     
     
         10 . The process of  claim 1 , wherein the branched alkyl sulfate surfactant has an average number of carbon atoms ranging from 8 to 22. 
     
     
         11 . The process of  claim 1 , wherein the branched alkyl sulfate surfactant is derived from a C 12  alcohol. 
     
     
         12 . The process of  claim 1 , wherein the at least one ethoxylated tristyrylphenol-based surfactant has an ionic moiety selected from the group consisting of sulfonate, phosphate, carboxylate, and alkyl ammonium. 
     
     
         13 . The process of  claim 1 , wherein the at least one non-polymerizable surfactant is a mixture of from about 0.05 to about 0.2 weight percent based on monomer content of at least one branched alkyl sulfate surfactant and from about 1.1 to about 1.3 weight percent based on monomer content of at least one ethoxylated tristyrylphenol surfactant. 
     
     
         14 . The process of  claim 1 , wherein the polymer latex has a particle distribution size of 400 nm or less. 
     
     
         15 . The process of  claim 1 , wherein the polymer latex has a particle distribution size of less than 250 nm. 
     
     
         16 . The process of  claim 1 , wherein the polymer latex exhibits a glass transition temperature between about −20° C. to about 80° C. 
     
     
         17 . The process of  claim 1 , wherein the polymer latex exhibits a glass transition temperature between about 5° C. to about 80° C.