Method of preparing paper

Abstract

A method of preparing paper, or paperboard, using a hollow sphere polymer whose void has been created by swelling the polymer with a fixed or permanent base, incorporating the hollow sphere polymer into the paper, and drying the paper, is provided. Also provided is a paper produced by the method.

1 . A method of preparing a paper or paperboard, comprising the steps of: 
 (a) providing a hollow sphere polymer made by: 
 i. forming a core stage polymer by polymerizing at least one monoethylenically unsaturated monomer containing acid functionality,  
 ii. encapsulating said core stage polymer with at least one shell stage polymer, by emulsion polymerizing at least one shell stage monomer system in the presence of said core stage polymer, 
 wherein said shell stage polymer permits penetration of a fixed or permanent base,  
 wherein said shell stage polymer as a glass transition temperature of greater than 25° C.;  
 
 iii. contacting the resulting multi-stage polymer particles with fixed or permanent base, 
 wherein either (1) said shell stage polymer comprises at least 1% acid functional monomer, or (2) said contacting takes place in the presence of solvent;  
 
   (b) during the wet-end formation of said paper or paperboard, incorporating in said paper or paperboard a composition comprising said hollow sphere polymer; and    (c) drying said paper or paperboard.    
   
   
       2 . The method, according to  claim 1 , wherein said core stage polymer is formed by polymerizing from about 5% by weight to about 100% by weight, based on the total weight of core stage polymer, of said monoethylenically unsaturated monomer containing acid functionality, and from 0% by weight to about 95% by weight, based on the total weight of core stage polymer, of at least one nonionic monoethylenically unsaturated monomer; 
 wherein said shell stage polymer is formed by polymerizing from about 90% by weight to about 99.9% by weight, based on the total weight of shell stage polymer, of at least one nonionic monoethylenically unsaturated monomer, and from about 0.1% by weight to about 10% by weight, based on the total weight of shell stage polymer, of an acid-functional monoethylenically unsaturated monomer; and    wherein said acid-functional monoethylenically unsaturated monomer is added to the polymerization of said shell stage polymer over the 100% of the total shell stage monomer feed, when the particle size of said core stage polymer is from about 130 nm to about 2.0 microns.    
   
   
       3 . The method, according to  claim 1 , wherein said core stage polymer is formed by polymerizing from about 5% by weight to about 100% by weight, based on the total weight of core stage polymer, of said monoethylenically unsaturated monomer containing acid functionality, and from 0% by weight to about 95% by weight, based on the total weight of said core stage polymer, of at least one nonionic monoethylenically unsaturated monomer; 
 wherein said shell stage polymer is formed by polymerizing from about 90% by weight to about 99.9% by weight, based on the total weight of shell stage polymer, of at least one nonionic monoethylenically unsaturated monomer, and from about 0.1% by weight to about 10% by weight, based on the total weight of shell stage polymer, of an acid-functional monoethylenically unsaturated monomer; and    wherein said acid-functional monoethylenically unsaturated monomer is added to the polymerization of said shell stage polymer over the first 50% of the total shell stage monomer feed, when the particle size of said core stage polymer is less than about 130 nm.    
   
   
       4 . The method of claims  1 , wherein said shell stage polymer is crosslinked.  
   
   
       5 . The method of claims  1 , wherein said paper has a thickness of 0.5 mil to 2 mil.  
   
   
       6 . The method, according to  claim 1 , wherein said incorporated composition further comprises at least one pigment.  
   
   
       7 . A paper formed by the method of any one of claims  1 - 6 .  
   
   
       8 . A method of preparing a decorative laminate paper, comprising the steps of: 
 (a) providing a hollow sphere polymer made by: 
 i. forming a core stage polymer by polymerizing at least one monoethylenically unsaturated monomer containing acid functionality,  
 ii. encapsulating said core stage polymer with at least one shell stage polymer, by emulsion polymerizing at least one shell stage monomer system in the presence of said core stage polymer,  
 wherein said shell stage polymer permits penetration of a fixed or permanent base,  
 wherein said shell stage polymer has a glass transition temperature of greater than 25° C.;  
 iii. contacting the resulting multi-stage polymer particles with fixed or permanent base, 
 wherein either (1) said shell stage polymer comprises at least 1% acid functional monomer, or (2) said contacting takes place in the presence of solvent;  
 
   (a) contacting said decorative laminate paper with a composition comprising said hollow sphere polymer and at least one pigment, 
 wherein said contacting comprises either (1) coating said decorative laminate paper with said composition, or (2) during the wet-end formation of said decorative laminate paper, incorporating said composition in said decorative laminate paper; and  
   (b) drying said decorative laminate paper.    
   
   
       9 . A decorative laminate paper formed by the method of  claim 8.