Modified Polyolefins for Adhesive Strength and Thermal Stability

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Solution Overview

Problem

Unmodified amorphous poly-alpha-olefins (APAOs) have limited tensile strengths, adhesive shear strengths, and thermal stability, and cannot achieve covalent incorporation of reactive surface groups, making them unsuitable for many adhesive applications due to their reversible physical curing and rubber-like properties.

Innovation Solution

The development of modified polyolefins with a specific microstructure, using metallocene catalysts to produce unfunctionalized polymers that are then functionalized through free-radical graft polymerization with monomers containing functional groups, resulting in polymers with improved adhesion, cohesion, and heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If unmodified amorphous poly-alpha-olefins are used as adhesive raw materials, then they provide purely physical curing with thermoplastic reversibility, but they exhibit limited tensile strengths, adhesive shear strengths, and thermal stability

Engineering Contradiction:

Improvethermoplastic reversibilityVSAvoidtensile strength and adhesive shear strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent creates a composite material system combining amorphous poly-alpha-olefin base polymer with grafted functional monomers (carboxylic acids, carboxylic acid derivatives, silanes). This composite structure provides both the thermoplastic reversibility of the amorphous matrix and the enhanced strength through functional groups that enable covalent bonding and crosslinking, resolving the contradiction between reversibility and strength

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical parameters of the poly-alpha-olefin by grafting functional monomers onto the polymer chains. This parameter change introduces reactive groups that enable covalent incorporation of surface groups and improve tensile and adhesive strengths while maintaining the underlying thermoplastic character of the amorphous matrix

Inventive Principle:

Principle #35Parameter changes

2Strength

If silane-modified polyolefins are prepared by reaction with unsaturated silanes, then crosslinking is achieved leading to stiff, high-strength materials, but the materials become unsuitable for adhesive applications

Engineering Contradiction:

Improvehigh-strengthVSAvoidadhesive suitability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent applies partial crosslinking through silane modification rather than complete crosslinking. By controlling the degree of silane grafting and crosslinking, the material retains sufficient thermoplastic character and processability for adhesive applications while gaining enhanced strength and stability from the crosslinked network

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent carefully controls the concentration and type of silane monomers used for modification, adjusting parameters such as silane content, molecular weight, and grafting density to achieve an optimal balance between crosslinked strength and adhesive processability, making the material suitable for both high-strength and adhesive applications

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If substantially amorphous polyolefins are used for modification, then they provide good processability, but they have high polydispersity leading to poor material cohesion and outgassing problems

Engineering Contradiction:

ImproveprocessabilityVSAvoidmaterial cohesion

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent selects amorphous poly-alpha-olefins with controlled molecular weight and polydispersity parameters. By optimizing these parameters, the patent achieves a balance where the polymer maintains good processability and melt flow characteristics while minimizing low molecular weight fractions that cause outgassing and poor cohesion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces functional groups at specific locations along the polymer chains through grafting, creating local regions of enhanced cohesion and stability without compromising the overall processability of the amorphous matrix. The functional groups are distributed to provide uniform improvement in material cohesion

Inventive Principle:

Principle #3Local quality

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 modified polyolefins exhibit enhanced adhesion to various substrates, high flexibility, and balanced setting behavior, making them suitable for use in adhesives and sealants, while avoiding the disadvantages of completely amorphous polymer systems.

Implementation Method 1

using metallocene catalysts to produce unfunctionalized polymers

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

functionalized through free-radical graft polymerization with monomers containing functional groups

Methodology Applied

Scientific EffectFree-radical polymerization: Photopolymerisation

Data Source

PatentUS8530582B2Modified polyolefins with an exceptional profile of properties, process for preparation thereof and use thereof

Publication Date: 2013.09.10 EVONIK OPERATIONS GMBH

AI summary

The present invention relates to modified polyolefins with atactic structural elements, to processes for preparation thereof and to the use thereof, especially as an adhesive or as a constituent of adhesives.