Base Film of Modified Polyvinyl Alcohol and Its Preparation Method and Polarizer

Abstract

The present invention provides a base film of modified polyvinyl alcohol as well as a method for preparing the base film of modified polyvinyl alcohol and a polarizer made from the base film. The method includes steps of: (1) executing surface graft modification of nano-silicon dioxides with fluorinated silane to obtain modified nano-silicon dioxide powders; (2) adding the modified nano-silicon dioxide powders obtained from the step (1) to an aqueous solution of polyvinyl alcohol polymers, in order to prepare a composite solution of polyvinyl alcohol polymers; and (3) pouring the composite solution of polyvinyl alcohol polymers prepared from the step (2) onto a surface of a casting substrate to obtain a base film of modified polyvinyl alcohol (PVA). The present invention enhances the heat and humidity resistances and the stability of the PVA base film, and improves its mechanical performance and sticking-resistance.

1 . A preparation method for a base film of modified polyvinyl alcohol, wherein comprising preparation steps of:
 (1) executing surface graft modification of nano-silicon dioxides with fluorinated silane to obtain modified nano-silicon dioxide powders;   (2) adding the modified nano-silicon dioxide powders obtained from the step (1) and an anionic carboxylate fluorocarbonic surfactant to an aqueous solution of polyvinyl alcohol polymers, in order to prepare a composite solution of polyvinyl alcohol polymers; and   (3) pouring the composite solution of polyvinyl alcohol polymers prepared from the step (2) onto a surface of a casting substrate, in order to obtain a base film of modified polyvinyl alcohol;   wherein the fluorinated silane in the step (1) are selected from one or any mixture of dodecafluoro-heptyl-propyl-trimethoxy-silane, dodecafluoro-heptyl-propyl-methyl-dimethoxy-silane, tetramethyl-(perfluoro-hexyl-ethyl)propyl-trimethoxy-silane and tridecafluoro-octyl-trimethoxy-silane, and the weight of the added fluorinated silane is 33% to 40% of that of the nano-silicon dioxide; and   wherein a molecular formula of the anionic carboxylate fluorocarbonic surfactant in the step (2) is RF—CH 2 —COOH, wherein R represents a carbon chain of C 6  to C 10 , and the weight of the added modified silicon dioxide powders is 4% to 8% of that of the polyvinyl alcohol polymer.   
     
     
         2 . The preparation method for a base film of modified polyvinyl alcohol as claimed in  claim 1 , wherein the particle diameter of the nano-silicon dioxides in the step (1) is between 35 and 45 nm. 
     
     
         3 . The preparation method for a base film of modified polyvinyl alcohol as claimed in  claim 1 , wherein the weight of the surfactant added in the step (2) is 0.2% to 0.3% of that of the polyvinyl alcohol polymer. 
     
     
         4 . A preparation method for a base film of modified polyvinyl alcohol, wherein comprising preparation steps of:
 (1) executing surface graft modification of nano-silicon dioxides with fluorinated silane to obtain modified nano-silicon dioxide powders;   (2) adding the modified nano-silicon dioxide powders obtained from the step (1) to an aqueous solution of polyvinyl alcohol polymers, in order to prepare a composite solution of polyvinyl alcohol polymers; and   (3) pouring the composite solution of polyvinyl alcohol polymers prepared from the step ( 2 ) onto a surface of a casting substrate, in order to obtain a base film of modified polyvinyl alcohol.   
     
     
         5 . The preparation method for a base film of modified polyvinyl alcohol as claimed in  claim 4 , wherein the fluorinated silane in the step (1) are selected from one or the mixture of dodecafluoro-heptyl-propyl-trimethoxy-silane, dodecafluoro-heptyl-propyl-methyl-dimethoxy-silane, tetramethyl-(perfluoro-hexyl-ethyl)propyl-trimethoxy-silane and tridecafluoro-octyl-trimethoxy-silane. 
     
     
         6 . The preparation method for a base film of modified polyvinyl alcohol as claimed in  claim 4 , wherein the particle diameter of the nano-silicon dioxides in the step (1) is between 35 and 45 nm. 
     
     
         7 . The preparation method for a base film of modified polyvinyl alcohol as claimed in  claim 4 , wherein the weight of the fluorinated silane added in the step (1) is 33% to 40% of that of the nano-silicon dioxide. 
     
     
         8 . The preparation method for a base film of modified polyvinyl alcohol as claimed in  claim 4 , wherein the weight of the modified silicon dioxide powder added in the step (2) is 4% to 8% of that of the polyvinyl alcohol polymer. 
     
     
         9 . The preparation method for a base film of modified polyvinyl alcohol as claimed in  claim 4 , wherein an anionic carboxylate fluorocarbonic surfactant is further added in the step (2), and the molecular formula thereof is RF—CH 2 —COOH, wherein R represents a carbon chain of C 6  to C 10 . 
     
     
         10 . The preparation method for a base film of modified polyvinyl alcohol as claimed in  claim 9 , wherein the weight of the surfactant added in the step (2) is 0.2% to 0.3% of that of the polyvinyl alcohol polymer. 
     
     
         11 . A base film of modified polyvinyl alcohol, wherein the base film of modified polyvinyl alcohol comprises polyvinyl alcohol polymers, nano-silicon dioxide groups and fluorinated silane groups, the base film of modified polyvinyl alcohol has the following general formula: 
       
         
           
           
               
               
           
         
         wherein A group is the fluorinated silane group; and B group is the nano-silicon dioxide group; 
         wherein the fluorinated silane group is selected from one or any mixture of dodecafluoro-heptyl-propyl-trimethoxy-silane, dodecafluoro-heptyl-propyl-methyl-dimethoxy-silane, tetramethyl-(perfluoro-hexyl-ethyl)propyl-trimethoxy-silane and tridecafluoro-octyl-trimethoxy-silane. 
       
     
     
         12 . The base film of modified polyvinyl alcohol as claimed in  claim 11 , wherein iodine molecules are bonded in the polyvinyl alcohol polymers, wherein the nano-silicon dioxide group connected with the fluorinated silane groups is coated on the polyvinyl alcohol polymers and the iodine molecules. 
     
     
         13 . The base film of modified polyvinyl alcohol as claimed in  claim 11 , wherein the base film of modified polyvinyl alcohol and a protection film adhered on one surface or two surfaces of the base film of modified polyvinyl alcohol commonly form a polarizer.