Mouldable silicone gel compositions

• US 20040092655A1
• Filed: 10/09/2003
• Published: 05/13/2004
• Est. Priority Date: 04/02/2001
• Status: Abandoned Application

• Current Assignee: Takayoshi Otomo
• Original Assignee: Takayoshi Otomo
• Inventors: Otomo, Takayoshi
• Application Number:
  US10/682,445
• Publication Number:
  US 20040092655A1
• Time in Patent Office: Days
• US Class Current: 524/588
• CPC Class Codes: C08G 77/12 containing silicon bound to hydrogen C08G77/045 takes precedence
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08G 77/70 Siloxanes defined by use of the MDTQ nomenclature
• CPC Class Codes: C08L 83/00 Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 83/04 Polysiloxanes

Abstract

A mouldable silicone gel composition that forms a low compression set silicone gel that exhibits an excellent mould releasability comprising: A, 100 parts by weight of an organopolysiloxane having at least two alkenyl groups in each molecule, B, an organopolysiloxane having at least two silicon-bonded hydrogen atoms in each molecule, in an amount such that the molar ratio of silicon bonded hydrogen atoms in component B to alkenyl groups in component A is from 0.5:1 to 10: 1, C 100 to 500 parts by weight of organopolysiloxane whose molecule is free of both alkenyl groups and silicon bonded hydrogen, and D a platinum group catalyst, in an amount sufficient to effect the cure of the composition.

Claims

1. A mouldable silicone gel composition comprising:

A. 100 parts by weight of an organopolysiloxane having at least two alkenyl groups in each molecule,

B. an organopolysiloxane having at least two silicon-bonded hydrogen atoms in each molecule, in an amount such that the molar ratio of silicon bonded hydrogen atoms in component B to alkenyl groups in component A is from 0.5;

1 to 10;

1,

C. greater than 200 parts to 500 parts by weight of an organopolysiloxane which is free of alkenyl groups and free of silicon bonded hydrogen, and

D. a platinum group catalyst, in an amount sufficient to effect the cure of the composition.

2. The mouldable silicone gel composition in accordance with claim 1, which additionally comprises a component E, a finely divided silica, in an amount of from 1 to 100 parts by weight per 100 parts by weight of component A.

3. The mouldable silicone gel composition in accordance with claim 1 wherein component A is selected from at least one of the group consisting of:

i. dimethylalkenylsiloxy-endblocked dimethylpolysiloxanes;

ii. dimethylalkenylsiloxy-endblocked dimethylsiloxane-methylalkenylsiloxane copolymers;

iii. trimethylsiloxy-endblocked dimethylsiloxane-methylalkenylsiloxane copolymers;

iv. organopolysiloxanes comprising the (CH₃)₃SiO_1/2, (CH₃)₂(alkenyl)SiO_1/2, and SiO_4/2 siloxane units;

v. organopolysiloxanes as defined in i to iv above wherein a proportion of the methyl groups are replaced by an organic group selected from the group of ethyl, propyl, phenyl tolyl and/or 3,3,3-trifluoropropyl;

wherein the alkenyl group is selected from the group of vinyl, allyl, propenyl, butenyl, pentenyl, and hexenyl.

4. The mouldable silicone gel composition in accordance with claim 1 wherein component B is selected from at least one of the group consisting of:

i dimethylhydrogensiloxy-endblocked dimethylpolysiloxanes;

ii. trimethylsiloxy-endblocked methylhydrogenpolysiloxanes;

iii. trimethylsiloxy-endblocked dimethylsiloxane-methylhydrogensiloxane copolymers;

iv. cyclic methylhydrogenpolysiloxanes;

v. organopolysiloxanes comprising the (CH₃)₂HSiO_1/2 and SiO_4/2 siloxane units; and

vi. organopolysiloxanes as defined in i to v above wherein a proportion of the methyl groups are replaced by an organic group selected from the group of ethyl, propyl, phenyl tolyl and/or 3,3,3-trifluoropropyl.

5. The mouldable silicone gel composition in accordance with claim 1 wherein component C is selected from the group consisting of:

a trimethylsiloxy-endblocked dimethylpolysiloxane,

a trimethylsiloxy-endblocked dimethylsiloxane-methylphenylsiloxane copolymer,

a trimethylsiloxy-endblocked dimethylsiloxane-diphenylsiloxane copolymer,

a dimethylphenylsiloxy-endblocked dimethylpolysiloxane and

a dimethylphenylsiloxy-endblocked dimethylsiloxane-methylphenylsiloxane copolymer

6. A method of producing a silicone gel composition in accordance with claim 2 comprising the steps:

i. intermixing components A and E, and optionally a proportion of component C with heating to form a silicone gel base; and

then

ii. adding components B and D and all or any remaining part of component C to the silicone gel base made in step i.

7. A moulded silicone gel made from a composition in accordance with claim 1.

8. A moulded silicone gel in accordance with claim 7 having an Asker C hardness of from 1 to 30°

.