Newsprint paper for offset printing

Abstract

A method of manufacturing a newsprint paper for offset printing, includes: selecting a filler or fillers having an average grain size of 0.5 to 5 μm and a zeta potential of 0 mV or above; providing a pulp slurry for making a base paper; adding the filler or fillers to the pulp slurry in an amount of more than 15 percent by weight but less than 40 percent by weight as ash relative to the dry weight of the base paper; and subjecting the resultant slurry to a papermaking machine to obtain the base paper.

1 . A newsprint paper for offset printing comprising a filler or fillers having a zeta potential of 0 mV or above, and having an ash content of more than 15 percent by weight but less than 40 percent by weight relative to the paper weight, said ash content being attributed at least partially by the filler or fillers. 
   
   
       2 . The newsprint paper for offset printing according to  claim 1 , which comprises deinked pulp (DIP). 
   
   
       3 . The newsprint paper for offset printing according to  claim 1 , which comprises calcium carbonate as a filler in an amount of more than 15 percent by weight but less than 40 percent by weight as ash relative to the paper weight. 
   
   
       4 . The newsprint paper for offset printing according to  claim 1 , wherein the filler or fillers have an average grain size of 0.5 to 5 μm. 
   
   
       5 . The newsprint paper for offset printing according to  claim 1 , which comprises no dispersant contained in the filler or fillers. 
   
   
       6 . The newsprint paper for offset printing according to  claim 1 , which comprises a base paper and a clear coat applied thereon. 
   
   
       7 . The newsprint paper for offset printing according to  claim 2 , wherein the DIP accounts for at least 50% or more of the total pulp as solid content. 
   
   
       8 . A method of manufacturing newsprint paper for offset printing, comprising adding a filler or fillers having a zeta potential of 0 mV or above to a papermaking slurry for making a base paper of the newsprint paper, to increase an ash content per the newsprint paper weight to more than 15 percent by weight but less than 40 percent by weight. 
   
   
       9 . The method according to  claim 8 , wherein the papermaking slurry contains deinked pulp (DIP). 
   
   
       10 . The method according to  claim 8 , wherein calcium carbonate is added as a filler in an amount of more than 15 percent by weight but less than 40 percent by weight as ash relative to the paper weight. 
   
   
       11 . The method according to  claim 8 , wherein the filler or fillers have an average grain size of 0.5 to 5 μm. 
   
   
       12 . The method according to  claim 8 , wherein the filler or fillers contain no dispersant. 
   
   
       13 . The method according to  claim 8 , further comprising applying a clear coat on the base paper. 
   
   
       14 . The method according to  claim 9 , wherein the papermaking slurry contains the DIP in an amount of at least 50% or more of the total pulp solid content of the newsprint paper. 
   
   
       15 . A method of manufacturing a newsprint paper for offset printing, comprising:
 selecting a filler or fillers having an average grain size of 0.5 to 5 μm and a zeta potential of 0 mV or above;   providing a pulp slurry for making a base paper;   adding the filler or fillers to the pulp slurry, thereby increasing an ash content of the newsprint paper weight to more than 15 percent by weight but less than 40 percent by weight; and   subjecting the resultant slurry to a papermaking machine to obtain the base paper.   
   
   
       16 . The method according to  claim 15 , further comprising applying a clear coat on the base paper: 
   
   
       17 . The method according to  claim 15 , wherein the selecting step comprises selecting calcium carbonate: 
   
   
       18 . The method according to  claim 17 , wherein in the selecting step, precipitated calcium carbonate (PCC) produced by a chemical method is selected. 
   
   
       19 . The method according to  claim 18 , wherein the PCC contains no dispersant. 
   
   
       20 . The method according to  claim 15 , wherein the pulp slurry contains a deinked pulp at a highest proportion among constituent pulps.