Transparent Curable Silicone Composition with Tin Carboxylate Catalyst

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Solution Overview

Problem

Existing curable compositions containing organic polymers with reactive silicon groups often result in opaque cured articles due to bubble formation and require organotin-based catalysts, which are toxic, limiting their transparency and adhesiveness to substrates.

Innovation Solution

A curable composition comprising an organic polymer with reactive silicon groups, a bivalent tin carboxylate as a silanol catalyst, and an amine compound, which reduces bubble formation and enhances transparency, adhesiveness, and resistance to dust adhesion, using a combination that includes polyoxyalkylene and (meth)acrylic acid ester polymers with a bivalent tin carboxylate and amine compound.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If organotin-based catalysts are used for curing the organic polymer, then the curing reaction proceeds efficiently, but the toxicity increases and the transparency of the cured article deteriorates

Engineering Contradiction:

Improvecuring reaction efficiencyVSAvoidtoxicity

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces persistent organotin-based catalysts with a metal-free catalytic system comprising a carboxylic acid and an amine compound. This disposable-like approach uses readily available, non-toxic catalysts that complete their function and decompose harmlessly, eliminating the toxicity issue while maintaining curing efficiency through the synergistic action of the catalyst pair.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the chemical parameters of the catalyst system from organotin-based to metal-free carboxylic acid/amine combination. This parameter change fundamentally alters the toxicity profile while adjusting the catalytic mechanism to maintain effective silane hydrolysis and condensation reactions for polymer curing.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the composition is stirred to mix components, then the homogeneity improves, but bubble formation increases and transparency deteriorates

Engineering Contradiction:

ImprovehomogeneityVSAvoidtransparency

Core Design Contradiction:

Stability of the object's compositionVSIllumination intensity

Solution Approach 1:

The patent incorporates a defoaming agent into the composition formulation before use. This preliminary action prevents bubble formation during the stirring and curing process by providing a mechanism for bubble removal, allowing thorough mixing for homogeneity without compromising the transparency of the final cured article.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful effect of bubble formation into a beneficial outcome by using the bubble formation process itself as an indicator that mixing is occurring, while simultaneously incorporating defoaming agents that exploit the bubble formation mechanism to remove air pockets and improve transparency in the cured product.

Inventive Principle:

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

3Strength

If the adhesive is applied in large amounts, then the adhesiveness improves, but the external appearance deteriorates due to forced-out adhesive

Engineering Contradiction:

ImproveadhesivenessVSAvoidexternal appearance

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The patent formulates the adhesive composition to be transparent or colorless, eliminating the visual problem of colored adhesive forcing out from joints. The transparent cured article maintains the external appearance while providing sufficient adhesiveness through the optimized polymer-catalyst system, allowing large amounts to be applied without compromising aesthetics.

Inventive Principle:

Principle #32Color 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 produces a transparent cured article with reduced surface tackiness and improved adhesiveness, maintaining transparency and appearance over time by eliminating bubbles and avoiding organotin toxicity.

Implementation Method 1

crosslinked by the formation of a siloxane bond which follows a hydrolysis reaction of the reactive silicon group

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

a bivalent tin carboxylate as a silanol catalyst

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 3

an amine compound which has a function of raising an activity of the bivalent tin carboxylate

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS8759435B2Curable composition and cured article excellent in transparency

Publication Date: 2014.06.24 KANEKA CORP

AI summary

An object of the invention is to yield a highly transparent cured article wherein bubbles are less generated when a catalyst and others are added to a curable composition that contains an organic polymer having a silicon-containing group which can be crosslinked by the formation of a siloxane bond and then the resultant mixture is stirred. Another object thereof is to provide a cured article which is small in surface stickiness, slightly gets dirty over a long term, and has a practical adhesiveness. These objects are attained by a curable composition which comprises (A) an organic polymer having a silicon-containing group that can be crosslinked by the formation of a siloxane bond, (B) a bivalent tin carboxylate and (C) an amine compound having no reactive silicon group, and which turns transparent when cured; or a transparent cured article obtained by curing the composition.