Foundry sandcore mold release composition

Abstract

A release agent composition to facilitate separation of patterns and core boxes from foundry molds and cores comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone intermediate, a catalyst, and a solvent or a hydroxy-terminated polyalkylsiloxane. Further is provided a method to improve the release properties of molds removed from a pattern or core box comprising applying a composition of the invention to the pattern or core box surface. A process for synthesizing a fluorotelomer or cotelomer from fluoroalkene monomers or comonomers is also provided.

1 . A method of easing the separation of a workpiece from a substrate comprising coating at least one of the workpiece and the substrate with a mold release agent selected from the group consisting essentially of: 
 (a) a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene monomer, and a silicone intermediate;    (b) a cross-linkable fluorotelomer comprising repeat units derived from at least two fluoroalkene comonomers, and a silicone intermediate;    (c) a hydroxy-terminated polyalkylsiloxane; and, optionally, a catalyst, cross-linking agent, and a solvent.    
   
   
       2 . The method of  claim 1  wherein the cross-linkable fluorotelomer has an end group derived from a secondary alcohol or derivative thereof.  
   
   
       3 . The method of  claim 1  further comprising a crosslinking agent having the general formula:  
       M(OR 1 ) 4    
     wherein M is zirconium or titanium and each R 1  is, independently, an alkyl radical, a cycloalkyl radical, an aralkyl hydrocarbon radical, wherein each radical can contain from 2 to 12 carbon atoms per radical and each R 1  can be the same or different.  
   
   
       4 . The method of  claim 1  further comprising a catalyst having the general formula:  
       M(OR 2 ) 4    
     wherein M is zirconium or titanium and each R 2  is, independently, an alkyl, cycloalkyl, alkaryl hydrocarbon radical, wherein each radical can contain from about 1 to about 30 carbon atoms per radical, and each R 2  can be the same or different.  
   
   
       5 . The method of  claim 4  wherein each radical can contain from about 2 to about 18 carbon atoms per radical.  
   
   
       6 . The method of  claim 5  wherein each radical can contain from about 2 to about 12 carbon atoms per radical.  
   
   
       7 . The method of  claim 1  in which the mold release agent has the general formula:  
       H—(CX 2 ) p (Z) s (CX 2 ) p′ —B q D r    
     wherein X is H or F; 
 B is any repeat unit derived from a hydrofluorocarbon;  
 D is an end group derived from a secondary alcohol or —OH;  
 Z has the formula:  
                     
 each R, independently of each other, can be linear or branched alkyl, cycloalkyl, alkyl-substituted cycloalkyl, having from 1 to about 20 carbon atoms;  
 p and p′ are each, independently, an integer having a value in the range of from about 0 to about 1500;  
 q is a number from 0.02 to 0.4;  
 r is a number from 0.2 to 1.0; and  
 s an integer having a value in the range of from about 10 to about 13,500.  
 
   
   
       8 . The method of  claim 7  wherein at least 80% of X is F.  
   
   
       9 . The method of  claim 8  wherein at least 90% of X is F.  
   
   
       10 . The method of  claim 9  wherein at least 99% of X is F.  
   
   
       11 . The method of  claim 7  wherein p and p′ are each, independently, an integer having a value in the range of from about 36 to about 1500.  
   
   
       12 . The method of  claim 1   1  wherein p and p′ are each, independently, an integer having a value in the range of from about 60 to about 600.  
   
   
       13 . The method of  claim 7  wherein the mold release agent comprises, by weight percent: 
 30% to 60% hydroxy-terminated dimethyl siloxane;    30% to 75% inorganic or organic filler;    10% to 50% solvent or solvent blend;    7% to 13% titanium oxide; and    3% to 7% functional silane.    
   
   
       14 . The method of  claim 1  wherein the fluoroalkene monomer or comonomer comprises 2 to about 10 carbon atoms.  
   
   
       15 . The method of  claim 14  wherein the fluoroalkene monomer or comonomer comprises 2 to 3 carbon atoms.  
   
   
       16 . The method of  claim 1  wherein the workpiece is selected from the group consisting essentially of cores, molds, and castings.  
   
   
       17 . The method of  claim 16  wherein the workpiece is comprised of metal, glass fiber, wood, rubber, plastic, stone, silicate or aggregate.  
   
   
       18 . The method of  claim 1  wherein the substrate is selected from the group consisting essentially of molds, core boxes, dies, tools, and machine components.  
   
   
       19 . The method of  claim 18  wherein the substrate is comprised of metal, wood, glass fiber, rubber or plastic.  
   
   
       20 . A telomerization process for preparing a fluorotelomer comprising combining a fluoroalkene monomer and optionally a comonomer in a hydrofluorocarbon solvent with a free radical initiator and at least one secondary alcohol or derivative thereof.  
   
   
       21 . The process of  claim 20  carried out at temperatures in the range of about 100° C. to about 200° C. at autogenous pressure.  
   
   
       22 . The process of  claim 21  wherein the temperatures range from about 110° C. to about 180° C. at autogenous pressure.  
   
   
       23 . The process of  claim 22  wherein the temperatures range from about 120° C. to about 160° C. at autogenous pressure.  
   
   
       24 . The process of  claim 20  wherein the fluorotelomer has the general formula:  
       H—(CX 2 ) p B q D r    
     or a mixture of:  
       H—(CX 2 ) p B q  and H—(CX 2 )D r    
     wherein X, B, D, p, q, and r are as defined above.  
   
   
       25 . The process of  claim 20  further comprising combining a silicone intermediate with the fluoroalkene monomer or optional comonomer.  
   
   
       26 . The process of  claim 25  wherein the silicone intermediate has general formula 1 or 2:  
       R 1 (R 1   2 SiO) x SiR 1   3   1  (R 1   2 SiO) y   2  
     wherein 
 each R 1  can be the same or different and can be alkyl, alkoxy, phenyl, phenoxy, or substituted derivatives of each of the foregoing, or combinations of two or more thereof; wherein each R 1  has from 1 to about 10 carbon atoms;  
 x is an integer from 1 to about 20; and  
 y is an integer from about 3 to about 20.  
 
   
   
       27 . The process of  claim 26  wherein x is an integer from 1 to about 10.  
   
   
       28 . The process of  claim 26  wherein y is an integer from about 3 to about 10.