Room-Temperature Curing Adhesive Composition for High Strength
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Solution Overview
Problem
Existing adhesive compositions using polyoxyalkylene-based polymers with (meth)acryloyl groups do not achieve optimal mechanical properties in the resulting cured products, specifically in terms of strength and elongation.
Innovation Solution
A room-temperature curing adhesive composition is developed, containing a polyoxypropylene-based polymer with an average of not less than 0.6 (meth)acryloyl groups at its terminals and a methacrylate compound with a glass transition temperature above 60°C, along with an organic peroxide and a reducing agent, which undergoes Redox radical reaction to cure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyoxyalkylene-based polymers with (meth)acryloyl groups are used as main components, then the adhesive composition can be cured to form a rubbery cured product, but the mechanical properties (strength and elongation) of the cured product are insufficient
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by specifying polyoxypropylene-based polymers with terminal (meth)acryloyl groups and controlling the number average molecular weight to be 5,000 or more. It also specifies the presence of at least 0.6 (meth)acryloyl groups on average per molecule, which are critical parameters that directly improve the mechanical properties of the cured product while maintaining curability.
Solution Approach 2:
The patent creates a composite adhesive system by combining polyoxypropylene-based polymer (A) with specific additives including organic peroxide (C) and reducing agent (D) for Redox radical reaction curing. This composite approach allows the system to achieve both excellent mechanical properties and room-temperature curing capability, resolving the contradiction between strength and curing flexibility.
2Strength
If the polyoxypropylene-based polymer has a low number average molecular weight, then the viscosity of the adhesive composition is low and ease of operation is improved, but the mechanical properties of the cured product deteriorate
Solution Approach 1:
The patent optimizes the number average molecular weight parameter of the polyoxypropylene-based polymer to be 5,000 or more, which is the critical threshold that simultaneously ensures adequate mechanical properties in the cured product while maintaining acceptable viscosity for ease of application. This specific parameter range resolves the contradiction between strength and operability.
3Productivity
If UV light or electron ray irradiation is used for curing, then the (meth)acryloyl group can be polymerized and cross-linked effectively, but additional equipment and energy input are required
Solution Approach 1:
The patent replaces the mechanical/physical curing systems (UV light irradiation equipment or electron ray equipment) with a chemical curing system based on Redox radical reaction between organic peroxide and reducing agent. This substitution eliminates the need for complex curing equipment while maintaining effective polymerization and cross-linking, thus resolving the contradiction between productivity and device complexity.
Solution Approach 2:
The adhesive composition is designed to cure through self-contained chemical reaction (Redox radical reaction) between components already present in the formulation, without requiring external energy input or specialized equipment. The organic peroxide and reducing agent react spontaneously under appropriate conditions to generate radicals that drive polymerization, enabling the system to serve itself and eliminating dependency on external curing infrastructure.
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 achieves a cured product with significantly improved mechanical properties, including strength and elongation, surpassing conventional methods.
Implementation Method 1
a cured product having excellent mechanical properties is obtained by curing, through Redox radical reaction, a composition containing (i) a specific polyoxypropylene-based polymer having, at a terminal thereof, a (meth)acryloyl group and (ii) a methacrylate compound having a high glass transition temperature (Tg) in a state of a homopolymer
Implementation Method 2
A rubbery cured product is obtained by adding a polymerization initiator to an organic polymer having a (meth)acryloyl group, and then irradiating the organic polymer with an active energy ray, such as UV light and an electron ray, or heating the organic polymer to polymerize and cross-link the (meth)acryloyl group in the organic polymer
Data Source
AI summary
It is an object of the present invention to achieve an adhesive composition which enables provision of a cured product having excellent mechanical properties. In order to attain the foregoing object, an adhesive composition in accordance with an embodiment of the present invention contains: a polyoxypropylene-based polymer (A) which has, the terminal thereof, not less than 0.6 (meth)acryloyl groups on average and which has a number average molecular weight of not less than 5,000; a methacrylate compound (B) having a glass transition temperature of higher than 60° C. in a state of a homopolymer; an organic peroxide (C); and a reducing agent (D).