Surface Protective Film Adhesive Composition for Feedability

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Solution Overview

Problem

Surface protective films face challenges in achieving stable adhesive strength and feedability from a wound roll, as enhancing adhesive strength often compromises feedability, and vice versa, due to the poor compatibility of acrylic-based pressure-sensitive adhesives with polyolefin substrates, leading to delamination and adhesive residue issues.

Innovation Solution

A surface protective film with a pressure-sensitive adhesive layer comprising a blend of styrene-based elastomer, acrylic-based pressure-sensitive adhesive, and tackifier, where the styrene-based elastomer is 50-90% by mass, the acrylic-based adhesive is 1-40% by mass, and the tackifier is 1-49% by mass, optimized to balance adhesive strength and feedability, using a co-extrusion method for lamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the adhesive strength of the pressure-sensitive adhesive layer is enhanced by lowering hardness or increasing tack, then adhesive strength to adherend is improved, but adhesive strength to substrate layer increases and feedability from wound roll is deteriorated

Engineering Contradiction:
Improveadhesive strength to adherendVSAvoidfeedability from wound roll
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention changes the chemical composition parameters of the pressure-sensitive adhesive layer by incorporating specific components (polymer with glass transition temperature of 60°C or higher, and polymer with main chain containing aromatic rings) in controlled amounts (5-50 wt% and 5-40 wt% respectively). This parameter adjustment allows the adhesive to achieve high adhesive strength to adherend while maintaining appropriate adhesive strength to substrate, resolving the contradiction between adhesive performance and feedability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite pressure-sensitive adhesive layer by combining multiple polymer components with different functional properties: a base polymer providing adhesive strength, a high glass transition temperature polymer controlling adhesion to substrate, and an aromatic ring-containing polymer enhancing overall adhesive performance. This composite structure enables simultaneous achievement of high adhesive strength to adherend and controlled adhesion to substrate for good feedability.

Inventive Principle:
Principle #40Composite materials

2Strength

If acrylic-based pressure-sensitive adhesive is used to achieve stable adhesive strength, then adhesive performance is improved, but compatibility with polyolefin substrate is poor leading to delamination

Engineering Contradiction:
Improveadhesive strengthVSAvoidinterlaminar strength
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention adjusts the glass transition temperature parameter of the adhesive composition by incorporating polymers with glass transition temperatures of 60°C or higher in specific amounts (5-50 wt%). This parameter change improves compatibility with polyolefin substrates and prevents delamination while maintaining stable adhesive strength to adherend.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention develops a composite adhesive system combining acrylic-based pressure-sensitive adhesive with polymers having complementary properties (high glass transition temperature and aromatic ring structures). This composite material approach resolves the incompatibility issue between acrylic adhesive and polyolefin substrate, preventing delamination while maintaining reliable interlaminar strength.

Inventive Principle:
Principle #40Composite materials

3Strength

If the adhesive strength is enhanced by increasing contact area through lowering hardness, then adhesive strength to adherend is improved, but the film becomes more prone to deformation during feeding

Engineering Contradiction:
Improveadhesive strengthVSAvoiddimensional stability during feeding
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The invention optimizes the glass transition temperature parameter of the adhesive composition by incorporating polymers with Tg ≥ 60°C in controlled amounts. This parameter adjustment provides the right balance between softness for contact area and structural stability, preventing excessive deformation during feeding while maintaining high adhesive strength to adherend.

Inventive Principle:
Principle #35Parameter changes

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 film achieves enhanced adhesive strength to adherends with protrusions while maintaining easy feedability and preventing adhesive residue, ensuring efficient bonding and removal without compromising transparency or interlaminar strength.

Implementation Method 1

a surface protective film comprising a polyolefin-based substrate layer and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer contains at least a styrene-based elastomer, an acrylic-based pressure-sensitive adhesive and a tackifier

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3072938B1Surface-protecting film
Publication Date: 2019.07.31 KURARAY CO LTD

AI summary

The surface protective film of the present invention is characterized in that the film comprises a polyolef in-based substrate layer and apressure-sensitive adhesive layer, the pressure-sensitive adhesive layer contains at least a styrene-based elastomer, an acrylic-based pressure-sensitive adhesive and a tackifier, and in the pressure-sensitive adhesive layer, the styrene-based elastomer is blended in an amount of not less than 50% by mass but not more than 90% by mass based on the total amount of the pressure-sensitive adhesive layer, the acrylic-based pressure-sensitive adhesive is blended in an amount of not less than 1% by mass but not more than 40% by mass based on the total amount of the pressure-sensitive adhesive layer, and the tackifier is blended in an amount of not less than 1% by mass but not more than 49% by mass based on the total amount of the pressure-sensitive adhesive layer.