Mother mold-forming silicone rubber composition and mother mold

• US 6,372,860 B1
• Filed: 04/05/2000
• Issued: 04/16/2002
• Est. Priority Date: 04/05/1999
• Status: Expired due to Fees

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Tanaka, Kouichi, Miyoshi, Kei
• Primary Examiner(s): Dawson, Robert
• Assistant Examiner(s): PENG, KUO LIANG
• Application Number:
  US09/520,885
• Time in Patent Office: 741 Days
• Field of Search: 524/267, 524/731, 524/700, 525/106, 525/477, 525/478, 525/479, 264/331.15, 264/331.11, 528/32, 528/31
• US Class Current: 525/477
• CPC Class Codes: C08G 77/14 containing silicon bound to oxygen-containing groups 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 77/24 halogen-containing groups
• CPC Class Codes: C08G 77/46 containing polyether sequences
• 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

In a silicone rubber composition comprising an organopolysiloxane as a base polymer, 0.1-50 parts by weight of a modified silicone fluid having a melting point of up to 100° C. and a refractive index difference of 0.01-0.05 from the base polymer is blended per 100 parts by weight of the composition. The composition is cast and cured to form a mother mold which maintains parting properties over a long term.

Claims

1. A silicone rubber composition for forming mother molds comprising

a linear dimethylpolysiloxane having at least two alkenyl radicals in a molecule as a base polymer, and

up to 50 parts by weight of a polyether, C₆-C₃₀ alkyl, higher fatty acid ester, fluorine, or phenyl-modified silicone fluid which is liquid at 20°

C. and has a refractive index which differs by at least 0.01 and up to 0.05 from the refractive index of the base polymer per 100 parts by weight of the composition.

2. The composition of claim 1, wherein the base polymer has a viscosity of 1000 to 100,000 centipoise at 25°

C.

3. The composition of claim 1, wherein the modified silicone fluid has a refractive index which differs from the refractive index of the base polymer by 0.02 to 0.05.

4. The composition of claim 1, which comprises 0.1 to 20 parts by weight of the modified silicone fluid per 100 parts by weight of the composition.

5. A mother mold comprising a cured product of the silicone rubber composition of any one of claims 1 or 2 to 4.