Foamed Pressure-Sensitive Adhesive for Mobile Devices
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Solution Overview
Problem
Current foamed pressure-sensitive adhesive layers used in self-adhesive products, particularly for mobile devices, face challenges in achieving high thermal shear strength and shock resistance while maintaining bonding strength, especially under varying environmental conditions and mechanical stress.
Innovation Solution
A foamed pressure-sensitive adhesive layer based on polyvinylaromatic-polydiene block copolymers, comprising 39.8% to 51.8% elastomer, 35.0% to 58.0% adhesive resin, 2.0% to 15.0% plasticizer, and 0.0% to 18.0% further additives, with microballoons, where the elastomer component consists of at least 90% polyvinylaromatic-polydiene block copolymers, and the adhesive resin has specific properties to enhance bonding and shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a relatively high proportion of adhesive resin is added to achieve high bond strength, then bonding strength is improved, but thermal shear strength deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive resin, specifically using resins with a softening point of at least 85°C and a DACP of at least -20°C. This parameter optimization allows the adhesive to maintain both high bond strength and high thermal shear strength by selecting resins that do not soften excessively at elevated temperatures while still providing strong adhesion.
Solution Approach 2:
The patent creates a composite adhesive formulation by combining multiple components: polyvinylaromatic-polydiene block copolymers (39.8-51.8%), adhesive resins with specific properties (35.0-58.0%), and plasticizers (2.0-15.0%). This composite approach balances the competing requirements of bond strength and thermal stability by integrating materials with complementary properties.
2Strength
If adhesive resin proportion is increased to improve bond strength, then adhesion is improved, but shock resistance deteriorates
Solution Approach 1:
The patent optimizes the plasticizer content parameter (2.0-15.0% of the adhesive composition) to maintain shock resistance while using higher adhesive resin proportions. The plasticizer acts as a shock-absorbing component that prevents the adhesive from becoming too rigid, thereby maintaining reliability despite increased resin content for bond strength.
Solution Approach 2:
The composite adhesive formulation integrates plasticizers with specific softening points below 30°C alongside the adhesive resins. This composite structure creates a material that is both strong (from the resin) and shock-resistant (from the plasticizer), resolving the contradiction between adhesion strength and shock resistance.
3Strength
If adhesive resin is added to improve bond strength, then adhesion is improved, but removability deteriorates
Solution Approach 1:
The patent carefully controls the adhesive resin parameters (softening point ≥85°C, DACP ≥-20°C) and proportion (35.0-58.0%) to achieve an optimal balance. The plasticizer content (2.0-15.0%) is also optimized to ensure the adhesive remains somewhat flexible and removable despite the high resin content, allowing strength and removability to coexist.
Data Source
AI summary
The present invention relates to a foamed pressure-sensitive adhesive compound on the basis of aromatic polyvinyl-polydiene block copolymers, in particular for double-sided self-adhesive strips, containing a) 39.8 wt.% to 51.8 wt.% of an elastomer component, b) 35.0 wt.% to 58.0 wt.% of an adhesive resin component, c) 2.0 wt.% to 15.0 wt.% of a plasticizer component, d) 0.0 wt.% to 18.0 wt.% of further additives and e) microballoons, the microballoons being at least partly expanded.