Variable dispersion of wet use chopped strand glass fibers in a chopped title strand mat

Abstract

A size composition for reinforcement fibers used to form non-woven mats that contain variable amounts of individual filaments dispersed from chopped reinforcement fiber bundles is provided. The size composition contains a polyvinylamine film former, one or more silane coupling agents, and, optionally a lubricant. The size composition works in conjunction with the whitewater components in a wet-laid mat forming process to disperse individual filaments from the bundles of chopped fibers. The whitewater contains an anionic polyacrylamide viscosity modifier and/or a cationic or non-ionic amine dispersant (e.g., ethoxylated amine). The presence of a cationic or non-ionic amine in the whitewater disperses individual filaments from the chopped glass fiber bundles. The greater the amount of cationic or non-ionic amine present in the whitewater, the greater the amount of fiber dispersion. The absence of a cationic or non-ionic amine and the presence of an anionic polyacrylamide viscosity modifier maintain full bundle formation integrity.

1 . A sizing composition for reinforcement fibers used in a wet-laid process, said sizing composition comprising:
 a polyvinylamine film former; and   one or more silane coupling agents,   wherein said polyvinylamine film former is capable of maintaining the integrity of reinforcement fiber bundles in whitewater or of interacting with components present in said whitewater to at least partially disperse individual reinforcement fibers from said reinforcement fiber bundles.   
   
   
       2 . The sizing composition of  claim 1 , further comprising a lubricant. 
   
   
       3 . The sizing composition of  claim 2 , wherein:
 said polyvinylamine film former is present in said composition in an amount from about 80 to about 95% by weight of the total composition;   said one or more silane coupling agents is present in said composition in an amount from about 5.0 to about 20.0% by weight of the total composition; and   said lubricant is present in said size composition in an amount up to about 5% by weight of the total composition.   
   
   
       4 . The sizing composition of  claim 1 , wherein said polyvinylamine film former has a molecular weight in a range from about 10 3  g/mol to about 10 6  g/mol. 
   
   
       5 . The sizing composition of  claim 4 , wherein said one or more silane coupling agents includes an epoxy silane coupling agent and an aminosilane coupling agent. 
   
   
       6 . The sizing composition of  claim 5 , wherein said polyvinylamine film former has a molecular weight selected from the group consisting of 10 3  to 10 4  g/mol, 10 4  to 10 5  g/mol and 10 5  to 10 6  g/mol. 
   
   
       7 . A chopped strand mat formed by a wet-laid process including whitewater for dispersing reinforcing fibers comprising:
 a plurality of chopped reinforcement fiber bundles formed of a plurality of individual reinforcement fibers at least partially coated with a sizing composition that contains a cationic polyvinylamine film former,   wherein said whitewater includes an anionic polyacrylamide thickening agent.   
   
   
       8 . The chopped strand mat of  claim 7 , further comprising:
 one or more of said individual reinforcement fibers released from said plurality of chopped reinforcement fiber bundles,   wherein said whitewater further includes an amine dispersing agent selected from a cationic amine and a non-ionic amine, and   wherein said amine causes the release of said individual reinforcement fibers from said chopped reinforcement fiber bundles.   
   
   
       9 . The chopped strand mat of  claim 8 , wherein said amine dispersing agent is an ethoxylated amine. 
   
   
       10 . The chopped strand mat of  claim 7 , wherein said individual reinforcement fibers are glass fibers, and
 wherein said polyvinylamine film former is cationic and said polyacrylamide thickening agent is anionic, and   wherein said cationic polyvinylamine film former and said anionic polyacrylamide thickening agent surround said chopped reinforcement fiber bundles and maintain said chopped reinforcement fiber bundles in a bundled form.   
   
   
       11 . The chopped strand mat of  claim 7 , wherein said polyvinylamine film former has a molecular weight in a range from about 10 3  g/mol to about 10 6  g/mol. 
   
   
       12 . The chopped strand mat of  claim 7 , wherein said sizing composition further comprises at least one silane coupling agent and a lubricant. 
   
   
       13 . The chopped strand mat of  claim 12 , wherein said at least one silane coupling agent comprises an epoxy silane coupling agent and an aminosilane coupling agent. 
   
   
       14 . A wet-laid method of forming a chopped strand mat that includes bundles of reinforcement fibers and a plurality of individual reinforcement fibers comprising the steps of:
 depositing bundles of reinforcement fibers formed of a plurality of individual reinforcement fibers in whitewater including a polyacrylamide thickening agent and an amine dispersing agent selected from a cationic amine dispersing agent and a non-ionic amine dispersing agent, said plurality of individual reinforcement fibers being at least partially coated with size composition containing a polyvinylamine film former;   agitating said whitewater to disperse said bundles of reinforcement fibers and selectively release said individual reinforcement fibers from said bundles of reinforcement fibers;   forming a web of said bundles of reinforcement fibers and said individual reinforcement fibers;   applying a binder composition to said web; and   heating said web to dry said web and cure said binder composition and form a chopped strand mat that includes said bundles of reinforcement fibers and said individual reinforcement fibers,   wherein said size composition works with said amine dispersing agent present in said whitewater to selectively disperse said individual reinforcement fibers from said bundles of reinforcement fibers.   
   
   
       15 . The method of  claim 14 , wherein said size composition further comprises one or more silane coupling agents. 
   
   
       16 . The method of  claim 15 , wherein said one or more silane coupling agent comprises an epoxy silane coupling agent and an aminosilane coupling agent. 
   
   
       17 . The method of  claim 16 , wherein said size composition further comprises a lubricant. 
   
   
       18 . The method of  claim 14 , wherein said amine dispersing agent is an ethoxylated amine. 
   
   
       19 . The method of  claim 14 , wherein said polyvinylamine film former has a molecular weight in a range from about 10 3  g/mol to about 10 6  g/mol. 
   
   
       20 . The method of  claim 14 , wherein said individual reinforcement fibers present in said whitewater is controlled by said amine dispersing agent in said whitewater to engineer said chopped strand mat with a predetermined amount of said individual reinforcement fibers.