Mold release agents employing polyvinyl alcohol
View Patent ↗The present invention relates to a composition designed to be a release agent applied to the surface of a molding apparatus and method of using the composition in molding operations. The composition includes a siloxane composition, hydrophilic matting particles, a cross linking agent, a binding agent having hydrophobic and hydrophilic characteristics. The composition may optionally include a carrier. The composition is designed to be applied to the surface of a mold, allowing for repeated use without the need for re-applying the composition between uses.
1. A mold release composition prepared from a mixture comprising:
a. a siloxane composition;
b. a cross linking agent;
c. a hydrophilic matting particles; and
d. a binding agent having hydrophobic and hydrophilic characteristics.
2. The mold release composition of claim 1 , wherein said binding agent comprises a partially hydrolyzed polyvinyl alcohol.
3. The mold release composition of claim 2 , wherein said polyvinyl alcohol is about 60% to about 99% hydrolyzed.
4. The mold release composition of claim 1 , wherein said binding agent has a molecular weight of from about 8,000 to about 100,000.
5. The mold release composition of claim 1 , wherein said mold release composition comprises about 0.1% to about 10.0% by weight binding agent.
6. The mold release composition of claim 1 , wherein said siloxane composition is of the formula:
wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are independently selected from a C 1-6 alkyl; A and B are independently selected from the group consisting of C 1-6 alkyl, C 2-6 allyl, C 1-4 alkoxy, silanol, carbinol, carboxy, acryloxy, acetoxy, halo, acryloxypropyl, aminopropyl and amino; and p is a number from about 500 to about 1,000.
7. The mold release composition of claim 1 , wherein said siloxane composition comprises silanol terminated polydimethylsiloxane.
8. The mold release composition of claim 1 , wherein said mold release composition comprises about 0.1% to about 5.0% by weight siloxane composition.
9. The mold release composition of claim 1 , wherein said hydrophilic matting particles are selected from the group consisting of silica and metal oxides.
10. The mold release composition of claim 1 , wherein said hydrophilic matting particles have an average particle size of from about 20 nm to about 10 μm.
11. The mold release composition of claim 1 , wherein said mold release composition comprises about 1.0% to about 10.0% by weight hydrophilic matting particles.
12. The mold release composition of claim 1 , wherein said mold release composition comprises about 0.1% to about 5.0% by weight siloxane composition;
about 1.0% to about 10.0% by weight matting particles; and about 0.1% to about 10.0% by weight binding agent.
13. The composition of claim 1 , wherein said composition is capable of providing a mold release coating useful in providing an article having a gloss value of less than about 1.0 as determined by a gloss meter.
14. The composition of claim 1 , further comprising a carrier.
15. The composition of claim 14 , wherein said carrier comprises water.
16. A method of releasing an elastomeric article from a molding apparatus, comprising the steps of:
providing the mold release composition of claim 1 :
applying said mold release composition to the surface of a mold in a molding apparatus;
heating the mold surface to cure the mold release composition;
forming an elastomeric article in said molding apparatus; and
releasing the elastomeric article from said molding apparatus.
17. The method of claim 16 , wherein said released elastomeric article has a low gloss finish.
18. The method of claim 16 , wherein said released elastomeric article has a matte finish.
19. The method of claim 16 , wherein said released elastomeric article has a low gloss value that is lower than about 1.0 as determined by a 60° gloss meter.
20. The method of claim 16 , wherein said released elastomeric article has a low gloss value that is from about 0.4 to about 0.6 as determined by a 60° gloss meter.
21. The method of claim 16 , wherein said step of releasing the elastomeric article from the mold in the molding apparatus can be repeated at least two times without repeating said step of applying said mold release agent to a mold in a molding apparatus.
22. The method of claim 16 , wherein multiple cycles of steps of forming an elastomeric article in said molding apparatus and releasing the elastomeric article from said molding apparatus are performed without substantial loss of low gloss value.
23. A mold for producing elastomeric articles comprising:
a mold surface; and
a cured reaction products of the mold release composition of claim 1 adhered to said surface.