Coating emulsion composition, and water/oil-repellent paper and making method

Abstract

An organopolysiloxane containing at least two silicon-bonded hydroxyl groups, the reaction product of an amino-containing organoalkoxysilane with a dicarboxylic anhydride, and an organopolysiloxane containing long-chain alkyl and alkoxy groups, but free of hydroxyl groups are emulsified and dispersed in water in the presence of a surfactant to form a coating emulsion composition.

1 . A coating emulsion composition comprising
 (A) 100 parts by weight of an organopolysiloxane containing at least two silicon-bonded hydroxyl groups in a molecule,   (B) 0.5 to 20 parts by weight of the reaction product of an amino-containing organoalkoxysilane with a dicarboxylic anhydride,   (C) 0 to 20 parts by weight of an epoxy-containing organoalkoxysilane and/or a partial hydrolyzate thereof,   (D) 0 to 50 parts by weight of colloidal silica and/or polysilsesquioxane,   (E) 0 to 10 parts by weight of a curing catalyst, and   (F) 0.5 to 20 parts by weight of an organopolysiloxane containing long-chain alkyl and alkoxy groups, but free of hydroxyl groups,   components (A) to (F) being emulsified and dispersed in water in the presence of a surfactant.   
     
     
         2 . The emulsion composition of  claim 1 , wherein component (F) has the average compositional formula (2): 
       
         
           
           
               
               
           
         
       
       wherein R 1  is each independently C 1 -C 3  alkyl or phenyl, Q is each independently C 4 -C 20  alkyl, Z is each independently a group of —OR 2 , —C 2 H 4 —Si(OR 2 ) 3  or —C 3 H 6 —Si(OR 2 ) 3  wherein R 2  is C 1 -C 6  alkyl, the subscript d is a positive number of 1 to 100, e is a positive number of 1 to 100, f is a positive number of 0.1 to 30, and q is 0, 1, 2 or 3. 
     
     
         3 . The emulsion composition of  claim 1 , wherein component (F) has the average compositional formula (3): 
       
         
           
           
               
               
           
         
       
       wherein Q is each independently selected from hexyl, octyl, decyl, and dodecyl, Z is each independently selected from methoxy, ethoxy and —C 2 H 4 —Si(OCH 3 ) 3 , the subscript d is a positive number of 1 to 100, e is a positive number of 1 to 100, and f is a positive number of 0.1 to 30. 
     
     
         4 . A water- and oil-repellent paper sheet having improved fold resistance, said paper sheet comprising a paper substrate and a water- and oil-repellent, releasable silicone resin layer on at least one surface of the paper substrate,
 said paper sheet including a planar portion normally and a folded portion when folded,   the planar portion exhibiting an oil resistance which is at least 9 in Kit value and the folded portion exhibiting an oil resistance which is at least 8 in Kit value, both as measured at 20° C and a humidity 50% by J. TAPPI paper/pulp test No. 41-83, and   the planar portion exhibiting a water repellency which is at least R8 and the folded portion exhibiting a water repellency which is at least R7, both as measured by J. TAPPI paper/pulp test No. 68:2000.   
     
     
         5 . The water- and oil-repellent paper sheet of  claim 4 , wherein said silicone resin layer is formed by coating a water- and oil-repellent composition on the surface of the paper substrate, said composition primarily comprising an aqueous silicone resin emulsion comprising
 (a) 100 parts by weight of an organopolysiloxane containing at least two silicon-bonded hydroxyl groups in a molecule,   (b) 0.5 to 20 parts' by weight of a dicarboxylic acid base curing agent,   (c) 1 to 50 parts by weight of silica,   (d) 2 to 4 parts by weight of an organopolysiloxane containing long-chain alkyl and alkoxy groups, but free of hydroxyl groups, and   (e) an effective amount to form an emulsion of a surfactant.   
     
     
         6 . A method for preparing a water- and oil-repellent paper sheet, comprising coating a water- and oil-repellent composition primarily comprising an aqueous silicone resin emulsion on at least one surface of a paper substrate so as to give a dry coating weight of at least 1.0 g/m 2 , for thereby forming a water- and oil-repellent, releasable silicone resin layer,
 the paper substrate being selected from the group consisting of kraft paper, wood-free paper, paper board, liner, glassine paper and parchment paper.   
     
     
         7 . The method of  claim 6 , wherein the water- and oil-repellent composition primarily comprises an aqueous silicone resin emulsion comprising
 (a) 100 parts by weight of an organopolysiloxane containing at least two silicon-bonded hydroxyl groups in a molecule,   (b) 0.5 to 20 parts by weight of a dicarboxylic acid base curing agent,   (c) 1 to 50 parts by weight of silica,   (d) 2 to 4 parts by weight of an organopolysiloxane containing long-chain alkyl and alkoxy groups, but free of hydroxyl groups, and   (e) an effective amount to form an emulsion of a surfactant.