White pitch deposit treatment

Abstract

The present invention relates to a deposit control system, consisting of an inorganic or organic (natural or synthesized) coagulant and a microparticulate material (synthetic or naturally-occurring) such as bentonite clay, cross-linked polymer, colloidal silica, polysilicate, for pulp containing white pitch/stickies.

1 . A process for making paper comprising adding to a paper stock an effective amount for reducing the deposition of white pitch of at least one cationic coagulant polymer or an inorganic coagulant and followed by the addition of a microparticle material, wherein the paper stock contains pulp derived at least in part from recycled paper products.  
     
     
         2 . A process according to  claim 1  wherein the microparticle material is selected from the group consisting of swellable clay materials, cross-linked polymer, colloidal silica, borosilicate or a suspension of microparticulate anionic material selected from bentonite, colloidal silica, polysilicate microgel, polysilicic acid microgel and crosslinked microemulsions of water soluble monomeric material and mixtures thereof.  
     
     
         3 . A process according to  claim 2  wherein the microparticle material is an anionic material.  
     
     
         4 . A process according to  claim 2  wherein the microparticle material is a swellable clay from the smectite family.  
     
     
         5 . A process according to  claim 4  wherein the microparticle material is a mineral selected from the group consisting of bentonite, montmorillonite, saponite, hectorite, beidilite, nontronite, fullers' earth and mixtures thereof.  
     
     
         6 . A process according to  claim 5  wherein the microparticle material is a mineral composed primarily of bentonite.  
     
     
         7 . A process according to  claim 1  wherein the cationic coagulant polymer is a homopolymer containing recurring cationic groups or a copolymer of at least 80% by weight cationic monomer and 0 to 20% by weight acrylamide or other non-ionic monomer.  
     
     
         8 . A process according to  claim 7  wherein the cationic groups are derived from the group consisting of diallyl dimethyl ammonium chloride and dialkylaminoalkyl (meth)-acrylates or dialkylaminoalkyl (meth)-acrylamides or quaternary ammonium salts thereof.  
     
     
         9 . A process according to  claim 8  wherein the cationic groups are dimethylaminoethyl acrylate or methacrylate quaternary ammonium salt.  
     
     
         10 . A process according to  claim 1  wherein the cationic coagulant polymer is a dicyandiamide polymer, a polyamine or a polyethyleneimine.  
     
     
         11 . A process according to  claim 1  wherein the inorganic coagulant is selected from the group consisting of alum, lime, ferric chloride, polyaluminum chloride, ferrous sulfate and mixtures thereof.  
     
     
         12 . A process according to  1  wherein the cationic coagulant polymer is a polyalkylenepolyamine prepared by the reaction of an alkylene polyamine with a difunctional alkyl halide.  
     
     
         13 . A process according to  claim 1  wherein the cationic coagulant polymer is a cationic polyelectrolyte that is a poly(diallyl di(hydrogen or lower alkyl) ammonium salt having a number average molecular weight greater than 300,000 but less than 2,000,000.  
     
     
         14 . A process according to  claim 13  wherein the microparticle material is a mineral composed primarily of bentonite.  
     
     
         15 . A paper product made according to the process of  claim 1 .  
     
     
         16 . A paper product made according to the process of  claim 6 .  
     
     
         17 . A paper product made according to the process of  claim 14.