Two-Part Curable Composition Flexibility Adhesion
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Solution Overview
Problem
Conventional two-part curable compositions based on 2-cyanoacrylic acid ester lack flexibility and adhesion durability, particularly when used between different types of adherends, and exhibit poor cold/hot cycle resistance and peel adhesion strength.
Innovation Solution
A two-part curable composition comprising a first reagent with 2-cyanoacrylic acid ester and a second reagent with a polymer having a hydrolyzable silyl group, along with an elastomer and a curing catalyst, to enhance flexibility and adhesion durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a 2-cyanoacrylic acid ester is used as the main component, then shear adhesion strength is improved, but flexibility and cold/hot cycle resistance deteriorate
Solution Approach 1:
The invention uses a composite adhesive system combining 2-cyanoacrylic acid ester with a polymer having hydrolyzable silyl groups (such as silane-modified polyisocyanate or silane-modified polyester). This composite approach allows the 2-cyanoacrylic acid ester to provide rapid bonding and high shear strength, while the polymer component with silyl groups provides flexibility and improved cold/hot cycle resistance through its molecular structure and crosslinking characteristics.
2Adaptability or versatility
If plasticizers and elastomers are added to improve flexibility, then flexibility is improved, but adhesion strength decreases with time due to bleeding out
Solution Approach 1:
Instead of using traditional plasticizers and elastomers that migrate and bleed out over time, the invention employs a polymer with hydrolyzable silyl groups that forms a stable crosslinked network. This network provides flexibility intrinsically through its molecular structure rather than through migratable additives, preventing the bleeding phenomenon and maintaining both flexibility and adhesion strength over time.
Solution Approach 2:
The invention changes the fundamental approach to achieving flexibility by using a polymer with hydrolyzable silyl groups that can form crosslinked structures with controlled flexibility. By adjusting the polymer structure, molecular weight, and crosslinking density, the invention achieves flexibility without relying on plasticizers, thereby maintaining long-term adhesion strength.
3Stability of the object's composition
If two-part liquids are applied separately to maintain composition stability, then composition stability is improved, but flexibility of the cured product deteriorates
Solution Approach 1:
The invention uses the polymer with hydrolyzable silyl groups as an intermediary component that bridges the 2-cyanoacrylic acid ester and the final crosslinked network. This intermediary polymer provides the flexibility characteristic to the cured product while maintaining compatibility with the two-part liquid system, allowing separate application and stable storage while achieving flexible cured joints.
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 excellent adhesion durability, including cold/hot cycle resistance and warm-water resistance, with improved flexibility and workability.
Implementation Method 1
the unique anion polymerization characteristics exhibited by its principal component, 2-cyanoacrylic acid ester, which initiates polymerization under the presence of weak anion provided by slight moisture or the like attached to a surface of an adherend
Implementation Method 2
a polymer having a hydrolyzable silyl group
Data Source
AI summary
Provided is a two-part curable composition which has excellent curability, and exhibits flexibility and adhesion durability. The two-part curable composition comprises a first reagent containing at least a 2-cyanoacrylic acid ester and a second reagent containing at least a polymer having a hydrolyzable silyl group, in which an elastomer and a curing catalyst for the above polymer are each contained in at least one of the first and second reagents in predetermined amounts. A preferable curing catalyst is a compound having a metal element and an organic group bonded to the metal element via oxygen, or an acid having a pKa of 4 or lower at 25°C. Preferably, a curing accelerator for 2-cyanoacrylic acid ester is contained in at least one of the first and second reagents.