Multilayer Pressure Sensitive Adhesive for Polyolefin Bonding

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Solution Overview

Problem

Pressure sensitive adhesives (PSAs) based on acrylic polymers often exhibit poor adhesion to polyolefin substrates due to the mismatch in surface energy, as acrylic polymers have high surface energy while polyolefin surfaces have low surface energy.

Innovation Solution

A pressure sensitive adhesive article comprising a substrate with a layer of acrylic polymer having a glass transition temperature (Tg) of -10°C or lower, in contact with a layer containing 20% to 90% polymerized units of high-aliphatic vinyl monomers, which improves adhesion to polyolefin substrates by reducing surface energy and enhancing wetting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If acrylic polymer is used as PSA, then chemical resistance and UV resistance are improved, but adhesion to polyolefin substrates deteriorates

Engineering Contradiction:

Improvechemical resistanceVSAvoidadhesion to polyolefin

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The adhesive system is divided into two distinct layers: a bottom layer (Lb) providing chemical resistance and UV resistance through acrylic polymer, and a top layer (Lc) providing adhesion to polyolefin through high-aliphatic vinyl monomer units. This segmentation allows each layer to independently optimize its function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the adhesive article are assigned different chemical compositions tailored to local requirements: the bottom layer uses acrylic polymer for durability and resistance properties, while the top layer uses high-aliphatic vinyl monomer for surface energy matching and adhesion to low surface energy substrates like polyolefin.

Inventive Principle:

Principle #3Local quality

2Reliability

If acrylic polymer with high surface energy is used, then chemical resistance is improved, but wetting of low surface energy polyolefin surfaces deteriorates

Engineering Contradiction:

Improvechemical resistanceVSAvoidwetting of polyolefin surface

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The adhesive is segmented into two layers with different surface energy characteristics. The bottom layer (Lb) uses acrylic polymer for chemical resistance, while the top layer (Lc) uses high-aliphatic vinyl monomer to provide low surface energy for effective wetting of polyolefin substrates.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The top layer of high-aliphatic vinyl monomer acts as an intermediary between the acrylic polymer adhesive and the polyolefin substrate, bridging the surface energy mismatch by providing a compatible interface that facilitates wetting while maintaining the underlying chemical resistance properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If high-aliphatic vinyl monomer content is increased to improve adhesion, then adhesion to polyolefin is improved, but polymerization control becomes more difficult

Engineering Contradiction:

Improveadhesion to polyolefinVSAvoidpolymerization control

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The polymer system is segmented into two separate layers, each with optimized monomer compositions. The top layer contains 20-90% high-aliphatic vinyl monomer for adhesion without requiring precise polymerization control, while the bottom layer uses conventional acrylic polymer composition.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The top layer uses a high concentration (20-90%) of high-aliphatic vinyl monomer units to ensure sufficient adhesion performance, accepting the trade-off of reduced polymerization control ease in exchange for reliable bonding to polyolefin substrates.

Inventive Principle:

Principle #16Partial or excessive action

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 described PSA article demonstrates improved peel strength and shear bonding to polyolefin surfaces, as evidenced by increased peel strength on HDPE and retained shear bonding to stainless steel, indicating enhanced adhesion and bonding performance.

Implementation Method 1

improves adhesion to polyolefin substrates by reducing surface energy and enhancing wetting

Methodology Applied

Scientific EffectSurface energy reduction: Surface Tension

Implementation Method 2

A pressure sensitive adhesive article comprising a substrate with a layer of acrylic polymer... in contact with a layer containing 20% to 90% polymerized units of high-aliphatic vinyl monomer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2941462B1Multilayer pressure sensitive adhesive

Publication Date: 2018.10.24 ROHM & HAAS CO

Figure 1~2

AI summary

Provided is a pressure sensitive adhesive article comprising (a) a substrate (Sa), (b) in contact with said substrate (Sa), a layer (Lb) of a composition (Cb) that comprises one or more acrylic polymer (POLb) having Tg of -10°C or lower, and (c) in contact with said layer (Lb), a layer (Lc) of a composition (Cc) that comprises one or more acrylic polymer (POLc) that comprises 20% to 90% polymerized units of one or more high-aliphatic vinyl monomer, by weight based on the weight of said polymer (POLc). Also provided is a bonded article made by a process of contacting a substrate (Sd) with such a pressure sensitive adhesive article, wherein said substrate (Sd) is in contact with said layer (Lc).