Process and compositions for repulping paper

Abstract

The present invention relates to a process and composition for the recovery of fibre from waste paper and paper broke which has been treated with wet-strength resins. Specifically the present invention is directed to the removal of such resins from the fibre material, so that such fibre material may be recycled to a paper web forming process, by using selected persulfates such as potassium persulfate. Optionally, the persulfate is used in combination with a surfactant. Improved repulping of the waste paper is achieved.

We claim:  
     
         1 . A repulping process for use on waste paper containing a wet-strength resin, comprising treating said waste paper, as an aqueous slurry, with a mixture of an alkali hydroxide and essentially 100% potassium persulfate.  
     
     
         2 . A process as claimed in    claim 1    wherein said process is conducted as a pH of between 8 to 12, and at a temperature the range of from 40° C. to 120° C.  
     
     
         3 . A process as claimed in    claim 2    wherein said temperature range is between 60° C. to 80° C.  
     
     
         4 . A repulping process for use on waste paper containing a wet-strength resin, comprising treating said waste paper, as an aqueous slurry, with a non-chlorinated oxidizer and a surfactant.  
     
     
         5 . A process as claimed in    claim 4    wherein said non-chlorinated oxidizer is an alkali or alkali earth metal persulfate or ammonium persulfate.  
     
     
         6 . A process as claimed in    claim 5    wherein said oxidizer is an alkali metal persulfate.  
     
     
         7 . A process as claimed in    claim 6    wherein said oxidizer is potassium persulfate.  
     
     
         8 . A process as claimed in    claim 4    wherein the level of the non-chlorinated oxidizer is between 0.1 to 10% by weight on the weight of pulp and oxidizer.  
     
     
         9 . A process as claimed in    claim 8    wherein the level of the oxidizer is between 0.5 to 5% by weight.  
     
     
         10 . A process as claimed in    claim 4    wherein said surfactant is a cationic, anionic and nonionic surfactant.  
     
     
         11 . A process as claimed in    claim 10    wherein said surfactant is a nonionic surfactant.  
     
     
         12 . A process as claimed in    claim 10    wherein said surfactant is an alkoxylated alcohol.  
     
     
         13 . A process as claimed in    claim 12    wherein said surfactant is an ethoxylated C9 to C11 alcohol.  
     
     
         14 . A process as claimed in    claim 4    wherein the level of said surfactant is between 0.1 to 10% by weight.  
     
     
         15 . A process as claimed in    claim 4    wherein the process is conducted at a pH of between 8 to 12; at a temperature in the range of from 40° C. to 120° C.; and at a pulp consistency of between 1% to 30% for a reaction time of from 1 to 280 minutes  
     
     
         16 . A process as claimed in    claim 15    wherein the process is conducted at a temperature of between 60° C. to 80° C., for a reaction time of from 60 to 120 minutes.  
     
     
         17 . A composition for use in the repulping of an aqueous slurry of a waste paper containing a wet-strength resin, which composition comprises a mixture of a non-chlorinated oxidizer and an surfactant.  
     
     
         18 . A composition as claimed in    claim 17    wherein said composition is a dry blend composition comprising between 0.1 to 20% (by weight of the composition) of said surfactant.  
     
     
         19 . A composition as claimed in    claim 17    wherein said composition comprises a mixture of an alkali metal or alkali earth metal persulfate or ammonium persulfate, and a nonionic surfactant.  
     
     
         20 . A composition as claimed in    claim 20    wherein said persulfate is potassium persulfate, and said surfactant is an ethoxylated C9 to C11 alcohol.