Pressure-Sensitive Adhesive Composition for Heat-Resistant Rough Bonding

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Solution Overview

Problem

Existing pressure-sensitive adhesive (PSA) compositions based on styrene-based block copolymers face challenges in maintaining cohesive strength at high temperatures while preserving good adhesion to rough surfaces and ensuring preservability.

Innovation Solution

A PSA composition comprising a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, combined with a tackifier resin that includes a natural product-based tackifier resin with a softening point above 80°C and a petroleum-based tackifier resin with an aromatic ring, achieving a balanced cohesive strength and adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a relatively hard PSA is used to improve cohesive strength at high temperature, then cohesive strength is improved, but adhesion to rough surface deteriorates

Engineering Contradiction:
Improvecohesive strength at high temperatureVSAvoidadhesion to rough surface
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the PSA by incorporating specific ratios of hydrogenated styrene-butadiene block copolymer (30-70 wt%), styrene-isoprene block copolymer (10-50 wt%), and C9-based petroleum resin (10-50 wt%). This parameter optimization enables the adhesive to achieve both high cohesive strength at elevated temperatures and good adhesion to rough surfaces, resolving the trade-off between these two properties.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite adhesive system by combining multiple polymer components (hydrogenated SBS block copolymer and SIS block copolymer) with a C9-based petroleum resin. This composite formulation synergistically provides both the structural integrity needed for high-temperature cohesive strength and the adhesive properties required for rough surface bonding, eliminating the need to choose between opposing performance characteristics.

Inventive Principle:
Principle #40Composite materials

2Reliability

If conventional tackifier resins with softening point below 110°C are used, then adhesion properties are improved, but cohesive strength at high temperature deteriorates

Engineering Contradiction:
Improveadhesion propertiesVSAvoidcohesive strength at high temperature
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention specifically selects C9-based petroleum resin with a softening point of 100-180°C, optimizing the resin's thermal properties to maintain cohesive strength at high temperatures while preserving adhesion performance. This parameter control of the tackifier resin resolves the contradiction between adhesion and high-temperature cohesion.

Inventive Principle:
Principle #35Parameter changes

3Strength

If phenol-based tackifier resin is added to improve adhesive strength, then adhesive strength is improved, but preservability deteriorates

Engineering Contradiction:
Improveadhesive strengthVSAvoidpreservability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention extracts and eliminates phenol-based tackifier resins from the adhesive composition, removing the source of deterioration while maintaining adhesive strength through alternative formulations using C9-based petroleum resin and optimized block copolymer combinations. This extraction of the harmful component resolves the contradiction between adhesive strength and preservability.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP4130187B1Pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet
Publication Date: 2025.12.10 NITTO DENKO CORP
  • EP4130187B1 patent drawingFigure 1~3
  • EP4130187B1 patent drawingFigure 4
  • EP4130187B1 patent drawing

AI summary

A PSA composition comprising a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, a tackifier resin, and a softening agent is provided. The tackifier resin comprises a natural product-based tackifier resin (A) having a softening point higher than 80°C and containing no aromatic ring, and a petroleum-based tackifier resin (B) having a softening point higher than 100°C and containing an aromatic ring. The content of the tackifier resin (A) is 40 to 120 parts by weight, the content of the tackifier resin (B) is 5 to 40 parts by weight, the total amount of the tackifier resin is 60 to 160 parts by weight, and the content of the softening agent is 5 to 40 parts by weight with respect to 100 parts by weight of the block copolymer, with respect to 100 parts by weight of the block copolymer,.