UV-Curable Silicone Composition for Fast Cure and Strong Adhesion

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Solution Overview

Problem

Conventional thiol-ene functional organopolysiloxane compositions cure quickly but suffer from poor adhesion to substrates, leading to adhesive failure when removed, limiting their use in applications where excellent adhesion is required.

Innovation Solution

A curable silicone composition comprising an organopolysiloxane with silicon-bonded aliphatically unsaturated groups, an organopolysiloxane with mercapto groups, a photoinitiator, and an acryloxy-functional silane, which can be cured via irradiation to form a product with excellent adhesion to substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional thiol-ene functional organopolysiloxane compositions are used for UV curing, then cure speed is improved, but adhesion to substrate deteriorates

Engineering Contradiction:

Improvecure speedVSAvoidadhesion to substrate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent combines thiol-ene functional organopolysiloxane (for fast UV curing) with epoxy-functional organopolysiloxane (for excellent adhesion) to create a composite curable composition. This composite approach allows the cured product to inherit both the rapid cure characteristics of thiol-ene groups and the superior adhesive properties of epoxy groups, thereby resolving the contradiction between cure speed and adhesion.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention merges two different functional groups (thiol-ene and epoxy) into a single curable composition system. By incorporating both types of functional groups with complementary properties, the composition achieves simultaneous optimization of cure speed (from thiol-ene) and adhesion (from epoxy), eliminating the need to choose between the two opposing characteristics.

Inventive Principle:

Principle #5Merging (Combining)

2Temperature

If UV curing is used to avoid heat exposure, then temperature control is improved, but curing of shadow areas deteriorates

Engineering Contradiction:

Improveheat exposureVSAvoidcuring of shadow areas

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The curable composition is designed with dual curing capability: it can cure via UV irradiation (for temperature-sensitive applications) and also via moisture curing (for shadow areas not accessible to UV light). This multi-functionality allows the composition to adapt to different curing scenarios, maintaining the benefit of low-temperature processing while also being able to cure in shadow regions through alternative mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If acrylate-functional organopolysiloxane compositions are used for UV curing, then cure speed is improved, but oxygen inhibition occurs

Engineering Contradiction:

Improvecure speedVSAvoidoxygen inhibition

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent uses thiol-ene functional groups instead of acrylate groups, as thiol-ene curing is not inhibited by ambient oxygen. This substitution converts the potential harm of oxygen exposure (which inhibits acrylate curing) into a benefit by selecting a curing mechanism (thiol-ene) that is inherently oxygen-tolerant, thereby maintaining fast cure speeds without suffering from oxygen inhibition issues.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 forms a cured product with superior adhesion to substrates, suitable for various end-use applications, including those where heat exposure is undesirable.

Implementation Method 1

UV curing of curable organopolysiloxane compositions is often utilized in preparing cured products where it is desirable to cure in the absence of heat

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

thiol-ene functional organopolysiloxane compositions are known to cure very quickly, including as compared to other functional groups known to be capable of UV curing

Methodology Applied

Scientific EffectThiol-ene reaction: Chemical Bonding

Data Source

PatentEP4536768B1Curable composition and method of forming cured product

Publication Date: 2026.03.18 DOW SILICONES CORP

AI summary

A curable composition comprises: (A) an organopolysiloxane having an average of at least two silicon-bonded aliphatically unsaturated groups per molecule; (B) an organopolysiloxane free from aliphatically unsaturated groups and having an average of at least two mercapto groups per molecule; (C) a photoinitiator; (D) an acryloxy-functional silane; and (E) a tetraorthosilicate.