Addition-Curable Silicone Adhesive Composition for Hot-Humidity Bond Retention
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Solution Overview
Problem
Existing addition-curable silicone adhesives experience a drop in adhesion when exposed to hot humid environments, despite curing rapidly at normal temperatures.
Innovation Solution
Incorporating a siloxane compound with an alicyclic epoxy group as a tackifier into the adhesive composition to enhance adhesion resistance in hot humid conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If normal temperature curing is used to reduce heating costs and improve productivity, then curing speed and productivity are improved, but adhesion strength in hot humid environments deteriorates
Solution Approach 1:
The invention uses a composite adhesive system combining polysiloxane base components with silane crosslinking agents and titanium dioxide. This composite formulation enables normal temperature curing while maintaining adhesion strength in hot humid environments through synergistic chemical reactions and material interactions.
Solution Approach 2:
The invention changes the chemical composition parameters of the adhesive by incorporating specific ratios of silane crosslinking agents and titanium dioxide content (1-10 parts by weight per 100 parts by weight of polysiloxane). These parameter adjustments enable the adhesive to cure at normal temperature while resisting adhesion loss in hot humid conditions.
2Reliability
If heating is applied to improve adhesion strength, then adhesion performance is improved, but energy consumption and production costs increase
Solution Approach 1:
The adhesive composition is formulated to cure autonomously at normal temperature through self-contained chemical reactions between the polysiloxane base, silane crosslinking agents, and moisture. The titanium dioxide catalyst enables this self-service curing process without external heating, eliminating energy consumption while achieving sufficient adhesion strength.
Solution Approach 2:
The invention replaces the thermal curing mechanism (mechanical/thermal system) with a chemical curing mechanism. The silane crosslinking reaction and titanium dioxide-catalyzed polymerization enable the adhesive to set at normal temperature, substituting the need for heating equipment and energy input.
3Reliability
If titanium dioxide is added to enhance adhesion and suppress adhesion drop, then adhesion reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention optimizes the titanium dioxide content parameter within a specific range (1-10 parts by weight per 100 parts by weight of polysiloxane) to achieve the desired adhesion reliability. By controlling this parameter and combining it with standard silane crosslinking agents, the formulation maintains simplicity while achieving the target performance.
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 adhesive composition maintains strong adhesion to substrates even after exposure to hot humid environments, eliminating the need for heating and reducing production costs.
Implementation Method 1
by adding a siloxane compound having an alicyclic epoxy group as a tackifier to an addition-curable silicone adhesive composition, the drop of adhesion which is incurred in a hot humid environment is suppressed
Implementation Method 2
Silicone adhesives of addition cure type rely on the curing mechanism of hydrosilylation reaction with the aid of a platinum catalyst
Data Source
AI summary
This composition comprises:(A) one or both of (i) and (ii), said (i) being polysiloxane (1) having a viscosity of 50-10,000,000 mPa·s,R2R12SiO(R12SiO)mSiR12R2 (1),and said (ii) being polysiloxane (2),(R13 SiO1/2)p(R2aR13-aSiO1/2)q(SiO4/2)r (2);(B) hydrogen polysiloxane (3),(HbR13-bSiO1/2)s(R13SiO1/2)2-s(HR11SiO2/2)t(R12SiO2/2)u (3);(C) a hydrosilylation catalyst; and(D) at least one among linear organosiloxane (4),(AcR33-cSiO1/2)v(R33SiO1/2)2-v(AR31SiO2/2)w(R32SiO2/2)x (4),and cyclic organopolysiloxane (5),(AR31SiO2/2)y(R32SiO2/2)z (5)(A is an alicyclic epoxy group represented by formula (6)),wherein the ratio of the total number of SiH's to the number of unsaturated bonds between (D) and the alkenyl of (A) is 0.8-1.5, said composition is rapidly cured at room temperature after mixing to exhibit adhesiveness to a substrate such as a metal or resin, and even after the cured product following adhesion is exposed to a high-temperature and high-humidity environment, the adhesiveness to the substrate does not deteriorate.