Dry silicone gels and their methods of making

Abstract

Methods and systems are provided for a dry silicone gel. The dry silicone gel comprises a base polymer having a vinyl-silicone group, a crosslinker, and a chain extender. The dry silicone gel may be made by reacting (a) a first set of components comprising a base polymer having a vinyl-silicone group and an addition cure catalyst with (b) a second set of components comprising a crosslinker, a chain extender, and additional base polymer. In certain circumstances, the base polymer and additional base polymer are vinyl-terminated polydimethylsiloxane.

What is claimed is: 
     
       1. A method of making a dry silicone gel comprising:
 providing a first set of components comprising: (1) a base polymer having a vinyl- silicone vinyl-silicone group, and (2) an addition cure catalyst; 
 providing a second set of components comprising: (1) a crosslinker having three or four Si-H groups, (2) a chain extender having two Si-H groups, and (3) additional base polymer having a vinyl-silicone group; and 
 mixing the first and second set of components together to form the dry silicone gel, wherein the dry silicone gel has a hardness between 100 g and 300 g, and a mole fraction of hydride present as crosslinker between 0.2 and 0.5, wherein the base polymer and additional base polymer are each a vinyl-terminated polydimethylsiloxane each having a molecular weight between 28,000 g/mol and 70,000 g/mol. 
 
     
     
       2. The method of  claim 1 , wherein the second set of components further comprises an inhibitor. 
     
     
       3. The method of  claim 2 , wherein the inhibitor is 3,5-dimethyl-1-hexyn-3-ol. 
     
     
       4. The method of  claim 1 , wherein the first and/or second set of components further comprises at least one additive selected from the group consisting of: flame retardants, coloring agents, adhesion promoters, stabilizers, fillers, dispersants, flow improvers, plasticizers, slip agents, toughening agents, and combinations thereof. 
     
     
       5. The method of  claim 1 , wherein the dry silicone gel comprises between 0.1 wt % and 25 wt % of a flame retardant additive. 
     
     
       6. The method of  claim 5 , wherein the flame retardant additive is zinc oxide. 
     
     
       7. The method of  claim 1 , wherein the base polymer and additional base polymer each have one or more of the following properties:
 (a) a viscosity between 500 mm 2 /s and 165,000 mm 2 /s; and 
 (b) a vinyl content between 0.01 mmol/g and 0.1 mmol/g. 
 
     
     
       8. The method of  claim 1 , wherein the dry silicone gel comprises one or more of the following properties:
 (a) a stress relaxation between 40% and 60% when the gel is subjected to a deformation of 50% of its original size; 
 (b) a compression set between 4% and 20% after 50% strain has applied to the gel for 1000 hours at 70° C.; and 
 (c) less than 10% oil bleed out after being under compression of 1.2 atm for 60 days at 60° C. 
 
     
     
       9. The method of  claim 1 , wherein the crosslinker is selected from the group consisting of tetrakis(dimethylsiloxy)silane, methyltris(dimethylsiloxy)silane, and combinations thereof. 
     
     
       10. The method of  claim 1 , wherein the chain extender is selected from the group consisting of hydride containing polydimethylsiloxane, dihydride containing siloxane, hydride terminated polyphenylmethylsiloxane, hydride terminated polydiphenylsiloxane, functionalized terminated silicone, and combinations thereof. 
     
     
       11. The method of  claim 1 , wherein the hydride to vinyl ratio in the dry silicone gel is between 0.8 and 1.0. 
     
     
       12. The method of  claim 1 , wherein the catalyst is selected from the group consisting of platinum complexed with divinyltetramethyldisiloxane, cobalt carbonyl complex, and rhodium chloride complex. 
     
     
       13. The method of  claim 1 , wherein the weight percent ratio between the first set of components and the second set of components is 1:1. 
     
     
       14. A method of making a dry silicone gel comprising:
 providing a first set of components comprising: 
 (1) a vinyl-terminated polydimethylsiloxane having a molecular weight between 28,000 g/mol and 70,000 g/mol, a viscosity between 3,000 mm 2 /s and 7,000 mm 2 /s, and a vinyl content between 0.01 mmol/g and 0.1 mmol/g, and 
 (2) an addition cure catalyst, wherein the catalyst is selected from the group consisting of platinum complexed with divinyltetramethyldisiloxane, cobalt carbonyl complex, and rhodium chloride complex; 
 providing a second set of components comprising: 
 (1) a crosslinker selected from the group consisting of tetrakis(dimethylsiloxy)silane, methyltris(dimethylsiloxy)silane, and combinations thereof, 
 (2) a chain extender selected from the group consisting of hydride containing polydimethylsiloxane, dihydride containing siloxane, hydride terminated polyphenylmethylsiloxane, hydride terminated polydiphenylsiloxane, functionalized terminated silicone, and combinations thereof, 
 (3) an inhibitor, and 
 (4) additional vinyl-terminated polydimethylsiloxane having a vinyl-terminated polydimethylsiloxane having a molecular weight between 28,000 g/mol and 70,000 g/mol, a viscosity between 3,000 mm 2 /s and 7,000 mm 2 /s, and a vinyl content between 0.01 mmol/g and 0.1 mmol/g; and 
 mixing the first and second set of components together to form the dry silicone gel, wherein the dry silicone gel has a mole fraction of hydride present as crosslinker between 0.2 and 0.5, wherein the hydride to vinyl ratio in the dry silicone gel is between 0.8 and 1.0, and wherein the weight percent ratio between the first set of components and the second set of components is 1:1, and wherein the dry silicone gel has a hardness between 100 g and 300 g. 
 
     
     
       15. A dry silicone gel prepared from a composition comprising:
 a base polymer having a vinyl-silicone group, wherein the base polymer is a vinyl-terminated polydimethylsiloxane having a molecular weight between 28,000 g/mol and 70,000 g/mol; 
 a crosslinker having three or four Si-H groups; and 
 a chain extender having two Si-H groups, wherein the dry silicone gel has a hardness between 100 g and 300 g, and a mole fraction of hydride present as crosslinker between 0.2 and 0.5. 
 
     
     
       16. The dry silicone gel of  claim 15  further comprising at least one additive selected from the group consisting of: flame retardants, coloring agents, adhesion promoters, stabilizers, fillers, dispersants, flow improvers, plasticizers, slip agents, toughening agents, and combinations thereof. 
     
     
       17. The dry silicone gel of  claim 16 , wherein the flame retardant additive is zinc oxide. 
     
     
       18. The dry silicone gel of  claim 15 , wherein the crosslinker is selected from the group consisting of tetrakis(dimethylsiloxy)silane, methyltris(dimethylsiloxy)silane, and combinations thereof. 
     
     
       19. The dry silicone gel of  claim 15 , wherein the chain extender is selected from the group consisting of hydride containing polydimethylsiloxane, dihydride containing siloxane, hydride terminated polydimethylsiloxane, hydride terminated polyphenylmethylsiloxane, hydride terminated polydiphenylsiloxane, functionalized terminated silicone, and combinations thereof. 
     
     
       20. The dry silicone gel of  claim 15  having a hydride to vinyl ratio between 0.8 and 1.0. 
     
     
       21. The dry silicone gel of  claim 15 , wherein the dry silicone gel comprises between 0.1 wt % and 25 wt % of a flame retardant additive. 
     
     
       22. The dry silicone gel of  claim 15 , wherein the base polymer has one or more of the following properties:
 (a) a viscosity between 500 mm 2 /s and 165,000 mm 2 /s; and 
 (b) a vinyl content between 0.01 mmol/g and 0.1 mmol/g. 
 
     
     
       23. The dry silicone gel of  claim 15 , wherein the gel comprises one or more of the following properties:
 (a) a stress relaxation between 40% and 60% when the gel is subjected to a deformation of 50% of its original size; 
 (b) a compression set between 4% and 20% after 50% strain has applied to the gel for 1000 hours at 70° C.; and 
 (c) less than 10% oil bleed out after being under compression of 1.2 atm for 60 days at 60° C.; and 
 (d) the hardness is 160 to 220 g.