Moisture-Curable Adhesive for Polyolefin Bonding

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Solution Overview

Problem

Existing adhesive compositions for automobile interior parts made of polyolefins lack sufficient heat resistance and adhesion, and alternatives with styrene copolymers suffer from phase separation issues when attempting to improve heat resistance.

Innovation Solution

A moisture-curable adhesive composition comprising a styrene block copolymer with unsaturated bonds, a hydrogenated styrene block copolymer with 15% or more styrene content, a silane compound with unsaturated bonds grafted onto the styrene block copolymer, an acid-modified polyolefin resin, and a polymerization initiator, which prevents phase separation and enhances heat resistance and adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If silane-modification of styrene copolymer is performed to improve heat resistance, then heat resistance is improved, but adhesion to polyolefins remains insufficient

Engineering Contradiction:
Improveheat resistanceVSAvoidadhesion to polyolefins
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The patent uses a composite adhesive system combining silane-modified styrene block copolymer (providing heat resistance) with acid-modified polyolefin resin (providing adhesion to polyolefin substrates). This composite approach allows both heat resistance and adhesion properties to be achieved simultaneously without phase separation.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical parameters of the styrene copolymer by introducing silane groups and controlling the block structure, while also adjusting the acid modification level of the polyolefin resin. These parameter changes enable the adhesive to maintain structural integrity at high temperatures while forming strong bonds with polyolefin surfaces.

Inventive Principle:
Principle #35Parameter changes

2Strength

If olefin bonding agent is added to improve heat-resistant adhesion, then adhesion is improved, but phase separation occurs

Engineering Contradiction:
Improveheat-resistant adhesionVSAvoidphase separation
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent achieves homogeneous mixing by using acid-modified polyolefin resin that is chemically compatible with both the silane-modified styrene block copolymer and the polyolefin substrate. The acid modification creates a transition layer that ensures uniform distribution of components without phase separation, while maintaining heat-resistant adhesion properties.

Inventive Principle:
Principle #33Homogeneity

3Object-affected harmful factors

If styrene copolymer adhesive is used as alternative to chloroprene adhesive, then environmental safety is improved, but heat resistance deteriorates

Engineering Contradiction:
Improveenvironmental safetyVSAvoidheat resistance
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent fundamentally changes the chemical parameters of styrene copolymer by introducing silane modification and controlling block structure, transforming it from a low-heat-resistance material to one capable of withstanding high temperatures. The silane groups form cross-linked structures that maintain adhesive integrity at elevated temperatures while keeping the adhesive free of halogen compounds for environmental safety.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite adhesive system where silane-modified styrene block copolymer provides the base adhesive matrix with environmental safety, while acid-modified polyolefin resin and silane cross-linking provide the necessary heat resistance. This composite structure achieves both environmental safety and heat resistance simultaneously.

Inventive Principle:
Principle #40Composite materials

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 adhesive composition provides excellent adhesion and heat resistance to polyolefins, making it suitable for adhering polyolefin molded articles to cover materials in automobile interior parts production without phase separation.

Implementation Method 1

a polymerization initiator (E), which is used in the graft reaction

Methodology Applied
Scientific EffectFree radical polymerization: Photopolymerisation

Implementation Method 2

a silane compound (C) having an unsaturated bond, which is grafted onto the component (A)

Methodology Applied
Scientific EffectGraft polymerization: Chemical Bonding

Implementation Method 3

a moisture-curable adhesive composition

Methodology Applied
Scientific EffectMoisture-curable crosslinking: Chemical Bonding

Data Source

PatentUS8921485B2Adhesive composition
Publication Date: 2014.12.30 SUNSTAR GIKEN KK

AI summary

The present invention relates to a moisture-curable adhesive composition applicable to production of automobile interior parts, having excellent adhesion to polyolefins such as polypropylene and polyethylene, and having excellent heat resistance. More specifically, the present invention relates to an adhesive composition comprising: a styrene block copolymer (A) having at least one unsaturated bond, a hydrogenated styrene block copolymer (B) having a styrene content of 15% by weight or more, a silane compound (C) having an unsaturated bond, an acid-modified polyolefin resin (D), and a polymerization initiator (E).