Adhesive Composition with Expandable Microspheres for Cellulosic Substrates

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Solution Overview

Problem

Traditional disposable food packages made from closed-cell extruded polystyrene foams are non-biodegradable and environmentally harmful, while alternatives using cellulosic substrates with adhesives lack sufficient insulation and structural integrity, especially when compressed.

Innovation Solution

A waterborne adhesive composition comprising a water-based polymer prepared by emulsion polymerization and expandable microspheres, which provides thermal insulation and structural integrity by expanding at elevated temperatures, eliminating the need for additional dividers and enhancing the insulating properties of cellulosic substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If cellulosic substrates are bonded together with adhesive to create environmentally friendly packages, then environmental sustainability is improved, but insulative properties and structural integrity deteriorate when compressed

Engineering Contradiction:
Improveenvironmental impactVSAvoidinsulative properties
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies composite materials by combining cellulosic substrates with a specialized adhesive composition containing expandable microspheres. This composite structure provides both environmental sustainability and enhanced insulative properties, as the microspheres create air pockets that improve thermal insulation while maintaining structural integrity under compression.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The adhesive composition incorporates expandable microspheres that create a porous structure when expanded. This porous network of air-filled spheres provides excellent thermal insulation by trapping air pockets between cellulosic substrates, preventing heat transfer while maintaining the package's structural strength during compression.

Inventive Principle:
Principle #31Porous materials

2Reliability

If dividers or higher basis weight substrates are used to improve insulation, then insulative properties are improved, but cost and carbon footprint increase

Engineering Contradiction:
Improveinsulative propertiesVSAvoidcost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the physical parameters of the adhesive material by incorporating expandable microspheres that undergo phase change when heated. The microspheres expand at elevated temperatures (beginning at 80°C-100°C with maximum expansion at 120°C-130°C), transforming the adhesive from a dense state to a porous, insulating foam structure that provides thermal protection without requiring additional materials.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The adhesive composition utilizes phase transition of the expandable microspheres from compressed to expanded state through heat treatment. This phase change occurs when the microspheres are heated during or after the lamination process, causing them to expand and create insulating air pockets that improve thermal properties without adding dividers or increasing substrate weight.

Inventive Principle:
Principle #36Phase transitions

3Ease of manufacture

If traditional adhesives are used to bond cellulosic substrates, then manufacturing simplicity is maintained, but structural integrity and insulation under compression deteriorate

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidstructural integrity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The adhesive composition serves multiple functions simultaneously: it acts as a bonding agent to join cellulosic substrates, provides structural reinforcement, and delivers thermal insulation. The expandable microspheres within the adhesive create a foam structure that enhances both mechanical strength and insulative properties, eliminating the need for separate dividers or support structures.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the functions of adhesive bonding and thermal insulation into a single integrated material system. The adhesive composition combines polymer binder with expandable microspheres, creating a unified material that performs both bonding and insulation functions, simplifying the manufacturing process while enhancing structural and thermal performance.

Inventive Principle:
Principle #5Merging (Combining)

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 offers improved thermal insulation and structural integrity to cellulosic substrates, maintaining insulation and structural support even under compression, and is environmentally friendly as it is biodegradable, reducing the carbon footprint and cost compared to traditional solutions.

Implementation Method 1

The expandable microspheres begin to expand at a temperature of 80°C to 100°C and have a maximum expansion temperature of 120°C to 130°C

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

an adhesive composition comprising (a) a water-based polymer prepared by emulsion polymerization

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3074479B1Adhesive for insulative articles
Publication Date: 2019.02.27 HENKEL IP & HOLDING GMBH
  • EP3074479B1 patent drawingFigure 1
  • EP3074479B1 patent drawingFigure 2

AI summary

An adhesive composition that improves structural integrity and insulative properties when applied to a cellulosic substrate is provided. The adhesive composition includes a plurality of microspheres and an emulsion-based polymer that has (i) an elastic modulus greater than 0.5MPa in the range temperature range of 70°C to 110°C; (ii) an absolute log(E)/T slope of less than 0.05 in the range temperature range of 70°C to 110°C; and (iii) a tan d value less than 0.6 at 90°C.