Polyester Adhesive Tape for Thin-Film Bonding and Moisture-Heat Peeling
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Solution Overview
Problem
Conventional adhesive tapes, particularly those using acrylic and polyester adhesives, face challenges in achieving sufficient adhesive strength, cohesive strength, and recyclability, while also posing environmental burdens due to non-combustible waste and low biodegradability.
Innovation Solution
A polyester adhesive composition is developed with specific structural units derived from aliphatic polycarboxylic acids and polyalcohols, optimized to have a crystal fusion heat of 30 J/g or less, containing 50 moles or more of aliphatic polycarboxylic acids with 4 or less carbon atoms, and limited 1,4-butanediol content, which enhances adhesive strength, recyclability, and biodegradability, and includes a crosslinking agent for improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If acrylic ester-based copolymer adhesive is used to make thin adhesive tape, then the tape thickness can be reduced to 30 μm or smaller, but the adhesive strength and cohesive strength become insufficient and adhesive residue is left when peeled off
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by specifying exact proportions of butyl acrylate (90-99 mass%), 2-ethylhexyl acrylate (1-10 mass%), and other components. It also controls molecular weight (700,000 or greater) and adds specific additives like waxes and oils to achieve the right balance of thin film performance with adequate strength and peelability
Solution Approach 2:
The adhesive composition is a complex composite containing multiple acrylic ester monomers, tackifiers (rosin and its derivatives), waxes (microcrystalline wax, paraffin wax), and mineral oils. This multi-component composite system provides synergistic effects that enable thin film application while maintaining adhesive strength and cohesive properties
2Length of stationary object
If adhesive tape is made to be thin for portable electronic terminals, then the device thickness is reduced, but the adhesive tape becomes difficult to peel off and disassemble
Solution Approach 1:
The patent adjusts the adhesive's glass transition temperature and viscosity by controlling the composition ratio of different acrylic ester monomers and adding plasticizers (mineral oils) and waxes. This creates an adhesive that remains tacky at room temperature for easy application but becomes peelable under moisture-heat conditions
Solution Approach 2:
The adhesive exhibits different properties under different environmental conditions: it maintains strong adhesion under normal conditions but becomes easily peelable when exposed to moisture and heat (periodic environmental exposure). This allows the tape to be permanently bonded during assembly but easily removed when needed for recycling or repair
3Strength
If conventional adhesive tapes are used for bonding main constituent members, then bonding strength is achieved, but the tapes cannot be easily separated and recycled, creating environmental burden
Solution Approach 1:
The adhesive is designed to respond periodically to environmental stimuli: under normal storage and use conditions, it provides strong bonding; when exposed to moisture and heat (such as during recycling processes), it becomes peelable. This time-dependent property change enables both strong bonding and easy recycling
Solution Approach 2:
The patent converts the typically harmful effect of moisture and heat (which can degrade adhesives) into a beneficial feature by designing an adhesive that specifically responds to moisture-heat exposure by becoming peelable. This allows the adhesive to provide strong bonding during normal use but facilitates easy separation and recycling when exposed to controlled moisture-heat conditions
Data Source
AI summary
To provide a polyester for use in an adhesive composition having excellent easy moisture-heat peelability in the form of a thin film, adhesive strength, holding strength, and solution stability, and highly effective in reducing environmental impact with excellent biomass degree, recyclability, and biodegradability. A polyester has a structural unit derived from polycarboxylic acids (a) and a structural unit derived from polyalcohols (b), wherein the polycarboxylic acids (a) contain aliphatic polycarboxylic acids (a1) having 4 or less carbon atoms, and a structural unit derived from the aliphatic polycarboxylic acids (a1) is in an amount of 50 moles or more in 100 moles of the structural unit derived from polycarboxylic acids (a). The polyester has a crystal fusion heat of 30 J/g or less or contains a structural unit derived from 1,4-butanediol in an amount of less than 50 moles in 100 moles of the structural unit derived from polyalcohols (b).