Silicone rubber composition for making key pad and key pad

Patent metadata

Field	Value
Publication number	US-10106668-B2
Application number	US-201715597723-A
Country	US
Kind code	B2
Filing date	May 17, 2017
Priority date	Jun 6, 2016
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

Provided is a silicone rubber composition suited for use as a key pad having excellent dynamic fatigue durability (keying durability) and a silicone rubber key pad obtained by curing molding of the composition.
A silicone rubber composition for making a key pad includes:
(A) 100 parts by weight of an organopolysiloxane represented by the following average compositional formula (1):

R 1 n SiO (4-n)/2   (1)

wherein R 1 is each independently the same or different and are an unsubstituted or substituted monovalent hydrocarbon group, and letter n is a positive number of 1.95 to 2.04, and having at least two alkenyl groups in one molecule;
(B) 10 to 100 parts by weight of reinforcing silica having a specific surface area of at least 50 m 2 /g when determined by BET method; (C) 0.1 to 10 parts by weight of a vinyl group-containing alkoxysilane; (D) 0.0001 to 0.2 part by weight of hydrochloric acid, calculated as hydrogen chloride in hydrochloric acid; (E) 0.01 to 5 parts by weight of a fatty acid ester and/or a fatty alcohol ester; and (F) an effective amount of a curing agent.

First claim

The invention claimed is:

1. A silicone rubber composition for making a key pad comprising:
(A) 100 parts by weight of an organopolysiloxane represented by the following average compositional formula (1):
R 1 n SiO (4-n)/2   (1)

wherein R 1 is each independently the same or different and are an unsubstituted or substituted monovalent hydrocarbon group, and letter n is a positive number of 1.95 to 2.04, and having at least two alkenyl groups in one molecule;
(B) 10 to 100 parts by weight of reinforcing silica having a specific surface area of at least 50 m 2 /g when determined by BET method;
(C) 0.1 to 10 parts by weight of a vinyl group-containing alkoxysilane;
(D) 0.0001 to 0.2 part by weight of hydrochloric acid, calculated as hydrogen chloride in hydrochloric acid;
(E) 0.01 to 5 parts by weight of a fatty acid ester and/or a fatty alcohol ester; and
(F) an effective amount of a curing agent.

2. The silicone rubber composition of claim 1 , wherein the reinforcing silica of component (B) is untreated silica.

3. The silicone rubber composition of claim 1 , wherein the curing agent of component (F) is a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst, or an organic peroxide.

4. A key pad made of a cured molding of the silicone rubber composition defined in claim 1 .

Assignees

• Shinetsu Chemical Co

Inventors

• Todoroki Daichi
• Igarashi Minoru

Classifications

• C08K5/11 Primary

  of acyclic polycarboxylic acids · CPC title

• C08L83/04 Primary

  Polysiloxanes · CPC title

• C08K2201/006

  Additives being defined by their surface area · CPC title

• C08K3/36

  Silica · CPC title

• C08K5/5419

  containing at least one Si—C bond · CPC title