Silicone Rubber Key Pad Composition Fatigue Durability
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Solution Overview
Problem
Recent key pad materials face challenges with dynamic fatigue durability due to increased strain from complex shapes and miniaturization, with existing silicone rubber compositions either being unsatisfactory in durability or economically unfavorable, and prone to corrosion or yellowing.
Innovation Solution
A silicone rubber composition comprising an organopolysiloxane with a high degree of polymerization, reinforcing silica, vinyl group-containing alkoxysilane, hydrochloric acid, and a fatty acid or alcohol ester, which improves dynamic fatigue durability while maintaining mechanical characteristics through uniform silica dispersion and crosslinking during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phosphoric acid ester having an alkyl group substituted with chlorine is used to improve dynamic fatigue durability, then keying durability is improved, but the making device undergoes corrosion
Solution Approach 1:
The patent replaces the harmful phosphoric acid ester with a fatty acid ester or fatty alcohol ester that does not cause corrosion. The new ester components provide the necessary dynamic fatigue durability without the harmful corrosive effects, effectively substituting a harmful material with a benign alternative that achieves the same functional goal.
Solution Approach 2:
The patent converts the harmful effect of chlorine-substituted phosphoric acid esters into a beneficial solution by using fatty acid esters or fatty alcohol esters that provide similar dynamic fatigue durability improvement without corrosion. The harmful corrosive property is eliminated while retaining the durability enhancement benefit.
2Reliability
If an organodisilazane having an alkenyl group is used to improve dynamic fatigue durability, then keying durability is improved, but the material is expensive and causes yellowing
Solution Approach 1:
The patent replaces the expensive organodisilazane with cheaper fatty acid esters or fatty alcohol esters that achieve comparable dynamic fatigue durability. This substitution reduces both the material cost and the harmful yellowing effect while maintaining the desired performance.
Solution Approach 2:
The patent eliminates the yellowing problem and high cost associated with organodisilazane by using fatty acid esters or fatty alcohol esters. The new components provide the same dynamic fatigue durability improvement without the harmful side effects of yellowing and excessive cost.
3Strength
If the degree of polymerization of organopolysiloxane is increased to improve mechanical characteristics, then strength is improved, but the material becomes more expensive
Solution Approach 1:
The patent optimizes the degree of polymerization parameter of the organopolysiloxane to achieve the desired mechanical characteristics at a lower cost. By carefully selecting the polymerization degree within an optimal range, the patent balances performance requirements with cost effectiveness, avoiding the need for excessively high polymerization degrees that would increase material cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves excellent dynamic fatigue durability and mechanical characteristics, effectively addressing the limitations of previous materials by enhancing keying durability and maintaining good mechanical properties.
Implementation Method 1
a vinyl group-containing alkoxysilane
Implementation Method 2
a vinyl group-containing alkoxysilane
Implementation Method 3
hydrochloric acid
Implementation Method 4
reinforcing silica having a specific surface area of at least 50 m2/g when determined by BET method
Implementation Method 5
a fatty acid ester and/or a fatty alcohol ester
Data Source
AI summary
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):R1nSiO(4-n)/2 (1)wherein R1 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 m2/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.