Acrylic Adhesive Composition Balancing Adhesion and Cohesion
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Solution Overview
Problem
Pressure sensitive adhesives designed for thermoplastic olefins like polypropylene and polypropylene/ethylene propylene diene terpolymer lack sufficient cohesive strength and long-term stability, especially when exposed to environmental elements, necessitating improved adhesive compositions that maintain high adhesion and cohesion over time.
Innovation Solution
An adhesive composition comprising specific ratios of (meth)acrylic based polymeric components A and B, along with a tackifier, where component A has a high glass transition temperature and component B is acid-free, and may include ethylenically unsaturated functional monomers, formulated to enhance adhesion and cohesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If pressure sensitive adhesives are designed for thermoplastic olefins to achieve high adhesion, then adhesion performance is improved, but cohesive strength deteriorates
Solution Approach 1:
The adhesive composition uses a composite system combining polymeric component A (at least 2 wt.% and not greater than 49 wt.%) with high Tg (at least 40°C) and polymeric component B (at least 51 wt.% and not greater than 98 wt.%) with low Tg (not greater than 20°C), along with a tackifier component (at least 0.1 wt.% and not greater than 30 wt.%). This composite structure allows the high Tg component A to provide cohesive strength while the low Tg component B and tackifier provide adhesion to thermoplastic olefins, resolving the contradiction between adhesion and cohesion.
2Reliability
If pressure sensitive adhesives are exposed to environmental elements for long-term durability, then stability is improved, but adhesion and cohesion performance deteriorates over time
Solution Approach 1:
The invention specifies precise parameter ranges for the adhesive composition: polymeric component A at least 2 wt.% and not greater than 49 wt.%, polymeric component B at least 51 wt.% and not greater than 98 wt.%, and tackifier component at least 0.1 wt.% and not greater than 30 wt.%. The glass transition temperature of component A is controlled at least 40°C and component B at not greater than 20°C. These controlled parameter changes ensure the adhesive maintains both high adhesion and cohesion even after years of exposure to environmental elements.
Data Source
AI summary
An adhesive composition may include at least about 2 wt. % and not greater than 49 wt. % of a (meth)acrylic based polymeric component A for a total weight of the adhesive composition, at least about 51 wt. % of a (meth)acrylic based polymeric component B for a total weight of the adhesive composition, and at least about 0.1 wt. % and not greater than about 30 wt. % of a tackifier component for a total weight of the adhesive composition. The (meth)acrylic based polymeric component A may have a glass transition temperature (Tg) of at least about 40° C. The (meth)acrylic based polymeric component B may have a glass transition temperature (Tg) of not greater than about 20° C. Further, the (meth)acrylic based polymeric component B may be acid-free.