Method for dissolving polyvinyl alcohol particles into aqueous media using high shear

Abstract

Various processes and methods are disclosed for incorporating polyvinyl alcohol additives into products. In one embodiment, polyvinyl alcohol particles are dissolved in a solvent without the use of external heat to form a polyvinyl alcohol solution for incorporation into a product. In an alternative embodiment, polyvinyl alcohol particles are directly incorporated into a starch-based adhesive composition. Through the processes of the present disclosure, solid polyvinyl alcohol particles can be delivered directly to a manufacturing facility where the product that incorporates the polyvinyl alcohol additive is being made or formulated. In this manner, since the polyvinyl alcohol particles are not predissolved, the costs associated with shipping and transporting the polyvinyl alcohol product are greatly reduced.

1 . A process for producing an adhesive composition comprising:
 combining a solvent comprising water with solid particles, the solid particles comprising polyvinyl alcohol;   mixing the combined solvent and solid particles in a high shear device using a shear rate of at least 100 sec -1  in the absence of any inorganic insoluble particles, the solvent and solid particles being mixed until the polyvinyl alcohol is substantially completely dissolved such that no more than 5% by weight undissolved polyvinyl alcohol particles are present to form an aqueous polyvinyl alcohol solution, the solvent and solid particles being mixed such that the resulting solution has a temperature of less than about 200° F.; and   formulating an adhesive composition containing the polyvinyl alcohol solution.   
     
     
         2 . (canceled) 
     
     
         3 . A process as defined in  claim 1 , wherein the polyvinyl alcohol particles comprise a powder having an average particle size of less than about 800 microns. 
     
     
         4 . A process as defined in  claim 1 , wherein the polyvinyl alcohol is from about 60 mole percent to about 99.3+ mole percent hydrolyzed. 
     
     
         5 . A process as defined in  claim 1 , wherein the polyvinyl alcohol has a viscosity at 4 percent solids and at 20° C. of less than about 75 cps. 
     
     
         6 . A process as defined in  claim 1 , wherein the polyvinyl alcohol solution contains polyvinyl alcohol in an amount equal or less than 60 percent by weight. 
     
     
         7 . A process as defined in  claim 1 , wherein the polyvinyl alcohol solution contains polyvinyl alcohol in an amount from about 20 percent to abut 30 percent by weight. 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . A process as defined in  claim 1 , wherein the solvent and solid particles are batch mixed. 
     
     
         11 . A process as defined in  claim 1 , wherein the solvent has an initial temperature of less than about 180° F. and the resulting polyvinyl alcohol solution has a final temperature after batch mixing of less than about 200° F. 
     
     
         12 . A process as defined in  claim 1 , wherein the solvent has an initial temperature of less than about 110° F. and the resulting polyvinyl alcohol solution has a final temperature after batch mixing of less than about 150° F. 
     
     
         13 . (canceled) 
     
     
         14 . A process as defined in  claim 8 , wherein the high shear device includes an impeller that rotates at a rate of 1,500 to 20,000 rpm during mixing. 
     
     
         15 . A process as defined in  claim 1 , wherein the solvent and solid particles are batch mixed for less than about 500 minutes. 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . A process as defined in  claim 10 , wherein the solvent and solid particles are batch mixed by being pumped into and out of a mixing tank. 
     
     
         19 . A process as defined in  claim 1 , further comprising the steps of combining starch, water, and a boron compound together to form a mixture and heating the mixture causing the starch to at least partially gelatinize; and
 adding the aqueous polyvinyl alcohol solution to the heated mixture.   
     
     
         20 . (canceled) 
     
     
         21 . A process for incorporating a polyvinyl alcohol into a product comprising:
 transporting to a product manufacturing facility a polyvinyl alcohol, the polyvinyl alcohol being in the form of solid particles;   at the product manufacturing facility, mixing the polyvinyl alcohol particles in a high shear device using a shear rate of at least 100 sec −1  with a solvent comprising water, the polyvinyl alcohol and the solvent being mixed without adding any external heat, the solvent and the polyvinyl alcohol being mixed until the polyvinyl alcohol is substantially completely dissolved to form a polyvinyl alcohol solution containing undissolved solids in an amount less than about 5 percent by weight;   at the product manufacturing facility, formulating a product; and   combining with the product being formulated with the polyvinyl alcohol solution.   
     
     
         22 - 31 . (canceled) 
     
     
         32 . A process for producing a starch adhesive comprising:
 heating together a first starch, a boron compound, and a base in a solvent to form a pre-adhesive composition, the pre-adhesive composition being heated at a temperature and for a time sufficient for at least a portion of the starch to gelatinize;   adding to the pre-adhesive composition a polyvinyl alcohol, the polyvinyl alcohol being in the form of solid particles; and   adding to the pre-adhesive composition with the polyvinyl alcohol or after the polyvinyl alcohol a second starch to form a starch adhesive.   
     
     
         33 - 42 . (canceled) 
     
     
         43 . A system for dissolving solid particles in a solvent comprising:
 a solid collections reservoir for holding solid particles;   a solids delivery device for conveying solid particles from the solid collection reservoir into a mixing tank, the mixing tank being configured to combine the solid particles with a solvent, the mixing tank including a first top end and a second bottom end, the second end defining an outlet;   a recirculation line having a first end and a second end, the first end being in fluid communication with the outlet of the mixing tank, the second end being in communication with the mixing tank; and   a high shear device in communication with the recirculation line, the high shear device for recirculating solid particles and a solvent into and out of the mixing tank, the high shear device being capable of providing a shear ratio of at least 100 sec-1 to the solid particles and solvent.   
     
     
         44 . A system as defined in  claim 43 , wherein the second end of the recirculation line is in communication with a nozzle configured to flow solid particles and a solvent being fed through the circulation line into the mixing tank, the nozzle being angled with respect to the recirculation line. 
     
     
         45 . (canceled) 
     
     
         46 . A system as defined in  claim 43 , wherein the high shear device comprises a centrifugal pump. 
     
     
         47 . A system as defined in  claim 43 , wherein the solid collection reservoir is in communication with a load cell, the load cell measuring the amount of solid particles being fed to the mixing tank. 
     
     
         48 . A system as defined in  claim 43 , wherein the system further comprises an additive pumping device for pumping a liquid additive into the mixing tank for blending with the solid particles and solvent. 
     
     
         49 . (canceled) 
     
     
         50 . (canceled)