Bio-based Pressure-Sensitive Adhesives Using Macromonomers

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Solution Overview

Problem

Current pressure-sensitive adhesives (PSAs) face limitations in incorporating high amounts of bio-based monomers due to compatibility issues with aqueous polymerization methods, restricting biomass content in polymerization products.

Innovation Solution

A pressure-sensitive adhesive composition is developed using the polymerization product of alkyl acrylates or methacrylates combined with a macromonomer derived from a hydroxy-functional ethylenically unsaturated monomer, a bio-based monomer like lactide, and a modifying monomer such as caprolactone, allowing for higher biomass incorporation and improved miscibility, thereby enhancing the preparation of polymerization products with at least 35% by weight of the macromonomer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If bio-based monomers are incorporated into pressure-sensitive adhesives, then sustainability and bio-based content are improved, but compatibility with aqueous polymerization methods deteriorates

Engineering Contradiction:

Improvebio-based contentVSAvoidcompatibility with aqueous polymerization

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by pre-modifying bio-based monomers (such as fatty acids and triglycerides) with acrylate groups before polymerization. This pre-functionalization introduces reactive double bonds that enable the bio-based monomers to participate in aqueous emulsion polymerization, thus resolving the compatibility issue while maintaining high bio-based content in the final adhesive composition.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If macromonomer content is increased in polymerization products, then biomass content is improved, but miscibility and processability deteriorate

Engineering Contradiction:

Improvebiomass contentVSAvoidmiscibility

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by systematically varying the molecular weight, functional group composition, and side-chain structure of macromonomers to optimize their miscibility with the polymer matrix. By adjusting these parameters, the patent achieves high biomass content (exceeding 35 wt%) while maintaining homogeneous mixing and processability of the adhesive composition.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If modifying monomers are added to macromonomers, then glass transition temperature is improved, but macromonomer structure complexity increases

Engineering Contradiction:

Improveglass transition temperatureVSAvoidmacromonomer structure

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent applies local quality by incorporating modifying monomers at specific positions within the macromonomer structure, particularly in the side chains or terminal regions. This localized modification allows precise control over the glass transition temperature and other properties without requiring complete structural redesign of the entire macromonomer, thus managing complexity while achieving desired thermal properties.

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 solution enables the preparation of polymerization products with high biomass content, achieving comparable adhesive properties to commercial PSAs while replacing petroleum-derived materials with bio-based alternatives, demonstrating enhanced miscibility and adhesive performance.

Implementation Method 1

a macromonomer comprising the reaction product of (a) a hydroxy-functional, ethylenically unsaturated monomer (e.g., a hydroxy alkyl acrylate or methacrylate where the alkyl group is a C1-C6 alkyl group), (b) a bio-based monomer (e.g., a lactide)

Methodology Applied

Scientific EffectRing-opening polymerization:

Implementation Method 2

The modifying monomer, which may be a bio-based monomer such as caprolactone, lowers the Tg of the macromonomer relative to the same macromonomer prepared in the absence of the modifying monomer

Methodology Applied

Scientific EffectCopolymerization:

Implementation Method 3

The enhanced miscibility of the macromonomer in the (A) monomer, relative to macromonomers that lack the modifying monomer, enables the preparation of polymerization products that contain relatively high amounts of the macromonomer

Methodology Applied

Scientific EffectMiscibility enhancement:

Data Source

PatentUS9469797B2Pressure-sensitive adhesives having high bio-based content and macromonomers for preparing same

Publication Date: 2016.10.18 REGENTS OF THE UNIVERSITY OF MINNESOTA

AI summary

A pressure sensitive adhesive composition comprising the polymerization product of: (A) a monomer selected from the group consisting of alkyl acrylates, alkyl methacrylates, and combinations thereof; and (B) a macromonomer comprising the reaction product of (a) a hydroxy-functional, ethylenically unsaturated monomer (e.g., an alkyl acrylate or methacrylate where the alkyl group is a C1-C6 alkyl group), (b) a bio-based monomer, and (c) a modifying monomer that lowers the Tg of the macromonomer relative to the Tg of the same macromonomer prepared in the absence of the modifying monomer.