Curable Adhesive Composition with Terminal Silyl Segmentation
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Solution Overview
Problem
Contact adhesives face challenges with low initial adhesion, long drying times, especially in winter, and high crosslink density leading to insufficient tack strength and short working life, due to the presence of trialkoxysilyl groups at both terminals of polymers, which cause premature curing and skin formation.
Innovation Solution
A curable composition comprising a linear organic polymer with a reactive silyl group at only one terminal and another organic polymer with reactive silyl groups, mixed in specific ratios, along with a polyoxypropylene backbone and a (meth)acrylic acid alkyl ester polymer, to achieve high initial tack development and long retention time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polymer with trialkoxysilyl groups at both terminals is used, then crosslink density increases, but initial tack strength decreases
Solution Approach 1:
The patent divides the polymer structure into segments with different functions: one terminal has a trialkoxysilyl group for crosslinking, while the other terminal has a different group that controls curing rate. This segmentation allows the adhesive to achieve both high crosslink density and high initial tack strength by preventing premature curing at both ends.
Solution Approach 2:
The patent applies local quality by giving each terminal of the polymer different chemical characteristics. One terminal is designed for crosslinking activity while the other terminal is designed to moderate the curing rate, creating localized functional differences that resolve the contradiction between crosslink density and initial tack.
2Speed
If a polymer with trialkoxysilyl groups at both terminals is used, then crosslinking speed increases, but working life decreases
Solution Approach 1:
The patent segments the curing process by having different terminals react at different rates. The trialkoxysilyl terminal provides crosslinking capability while the other terminal's structure is designed to control the overall curing speed, preventing immediate surface curing that would shorten working life.
Solution Approach 2:
The patent introduces dynamics by creating an asymmetric curing behavior where one terminal reacts faster than the other. This dynamic control of curing progression allows the adhesive to maintain workability for an extended period while still achieving rapid crosslinking where needed.
3Strength
If conventional solvent contact adhesives are used, then initial adhesion is achieved, but environmental safety deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of the adhesive system by transitioning from solvent-based to water-based emulsion formulation. This parameter change maintains the contact adhesive mechanism and initial adhesion properties while eliminating the harmful organic solvents, thereby improving environmental safety.
Solution Approach 2:
The patent uses composite materials by combining polymer particles in an aqueous emulsion matrix. This composite structure allows the adhesive to function as a contact adhesive with initial tack while being water-based, thus resolving the contradiction between adhesion performance and environmental safety.
4Object-affected harmful factors
If aqueous emulsion adhesives are used to improve environmental safety, then initial adhesion deteriorates
Solution Approach 1:
The patent changes key parameters of the emulsion system including polymer composition, molecular weight distribution, and surface properties to optimize initial adhesion. By adjusting these parameters, the aqueous emulsion achieves contact adhesive performance comparable to solvent-based systems while maintaining environmental safety.
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 exhibits high initial tack strength and extended tack retention time, improving adhesion and workability while maintaining low viscosity, suitable for practical applications as a contact adhesive.
Implementation Method 1
a silicon-containing group that contains a hydroxyl or hydrolyzable group bonded to a silicon atom and can form a siloxane bond to be cross-linked
Implementation Method 2
can form a siloxane bond to be cross-linked
Data Source
AI summary
The present invention provides a curable composition useful as a contact adhesive which has a high rate of initial tack development, high tack strength, and long retention time of the developed tack. The curable composition includes an organic polymer (Q) containing a reactive silyl group, and a linear organic polymer (P) having a number average molecular weight larger than that of the polymer (Q) and having a reactive silyl group containing three hydrolyzable groups at only one terminal. The organic polymer (P) and the organic polymer (Q) are mixed at a mixing ratio (P):(Q), in terms of parts by weight, of 60:40 to 5:95.