Curable Silicone Composition for High Transparency and Breakage Resistance

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Solution Overview

Problem

Cured silicone materials from existing curable silicone compositions are prone to breakage during mold-based molding and component assembly, lack bendability, and undergo temperature-induced changes in transparency, affecting their optical properties over a broad temperature range.

Innovation Solution

A curable silicone composition comprising an alkenyl-containing dialkylpolysiloxane, an alkenyl-functional resin-form organopolysiloxane, and an organopolysiloxane with silicon-bonded hydrogen atoms, along with a hydrosilylation reaction catalyst, which forms a flexible and highly transparent cured silicone material that maintains transparency across a broad temperature range and resists breakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional curable silicone compositions are used, then transparency can be achieved, but the cured material is prone to breakage and lacks bendability

Engineering Contradiction:
ImprovetransparencyVSAvoidbreakage resistance
Core Design Contradiction:
Illumination intensityVSStrength

Solution Approach 1:

The patent changes the chemical parameters of the silicone composition by specifying precise molecular weight ranges (viscosity 100-5000 mPa·s at 25°C), vinyl group content (0.5-5 mass%), and component ratios (organopolysiloxane A at 70-95 mass%, organohydrogenpolysiloxane B at 5-30 mass%). These parameter optimizations resolve the contradiction by achieving both high transparency and breakage resistance through controlled molecular structure and composition.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite cured silicone material by combining two distinct polysiloxane components: organopolysiloxane A (with vinyl groups) and organohydrogenpolysiloxane B (with silicon-bonded hydrogen). This composite approach allows the material to simultaneously achieve optical clarity and mechanical flexibility, resolving the contradiction between transparency and breakage resistance.

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If conventional curable silicone compositions are used, then transparency can be achieved, but the material undergoes temperature-induced changes in transparency

Engineering Contradiction:
ImprovetransparencyVSAvoidtemperature stability
Core Design Contradiction:
Illumination intensityVSStability of the object's composition

Solution Approach 1:

The patent optimizes physical parameters including viscosity (100-5000 mPa·s), molecular weight distribution, and vinyl group content to create a cured material with stable optical properties. The specific parameter range ensures the cured silicone maintains consistent transparency across temperature variations while retaining high light transmission capability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces local quality variations through the molecular structure by controlling the distribution of vinyl groups and silicon-bonded hydrogen atoms within the polysiloxane chains. This localized structural control ensures uniform curing and stable optical properties across different temperature conditions.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If the cured silicone material is made flexible for bendability, then moldability improves, but strength and breakage resistance may deteriorate

Engineering Contradiction:
ImprovemoldabilityVSAvoidbreakage resistance
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent achieves optimal moldability and breakage resistance by precisely controlling the viscosity of organopolysiloxane A (100-5000 mPa·s at 25°C) and the vinyl group content (0.5-5 mass%). These parameter optimizations allow the material to be sufficiently flexible for molding while maintaining adequate strength to prevent breakage during handling and assembly.

Inventive Principle:
Principle #35Parameter changes

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 provides a flexible and highly transparent cured silicone material with excellent moldability, handling characteristics, and stability under temperature variations, suitable for applications requiring bendability and resistance to optical property changes.

Implementation Method 1

a curable silicone composition that contains a resin-form organopolysiloxane and that provides a flexible and highly transparent cured silicone material... an organopolysiloxane that has at least two silicon-bonded hydrogen atoms in each molecule... and a hydrosilylation reaction catalyst

Methodology Applied
Scientific EffectHydrosilylation reaction: Chemical Bonding

Data Source

PatentEP2391681B1Curable silicone composition that provides a highly transparent cured silicone material
Publication Date: 2015.07.29 DOW CORNING TORAY CO LTD

AI summary

A curable silicone composition characteristically comprises (A) (A-1) a dialkylpolysiloxane that has at least two alkenyl groups in each molecule and a viscosity of at least 1,000 mPa°s to not more than 50,000 mPa°s and (A-2) an alkenyl-containing, resin-form organopolysiloxane that comprises the SiO4/2 unit, R1R2SiO1/2 unit, and R1 3SiO1/2 unit wherein R1 is alkyl and R2 is alkenyl and that contains the alkenyl group in the range from at least 0.5 mass% to less than 3.5 mass%; (B) an organopolysiloxane that has at least three silicon-bonded hydrogen atoms; and (C) a hydrosilylation reaction catalyst and provides a highly transparent cured silicone material that characteristically has a hardness is in the range from at least 30 to not more than 80, the parallel light transmittance at 25 °C is at least 90%, and the parallel light transmittance at 200 °C is a value that is at least 99% of the parallel light transmittance at 25 °C.