Waterborne Adhesive with Microspheres for Lightweight Packaging
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Solution Overview
Problem
Reducing the basis weight of multilayer substrates to improve environmental and economic sustainability compromises thermal insulation and strength, and existing solutions like microspheres in paper pulp lead to out-of-plane buckling, while increasing adhesive amounts slows down manufacturing and increases energy consumption.
Innovation Solution
A waterborne adhesive composition incorporating emulsion-based polymers and expandable microspheres, which provide thermal insulation and strength comparable to heavier substrates with up to 26% less basis weight, reducing carbon footprint and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the basis weight of substrates is reduced to improve environmental and economic sustainability, then the carbon footprint and material consumption are decreased, but the thermal insulation and strength of the article are compromised
Solution Approach 1:
The patent applies composite materials by incorporating microspheres into the adhesive composition. These microspheres create a composite adhesive system that combines the bonding properties of the adhesive with the insulating and reinforcing properties of the spherical particles, enabling reduced basis weight substrates to achieve sufficient strength and thermal insulation
Solution Approach 2:
The adhesive composition with microspheres creates a porous or cellular structure within the adhesive layer. This porous structure provides thermal insulation by trapping air pockets while maintaining structural integrity, allowing thinner and lighter substrates to achieve the required thermal performance
2Temperature
If microspheres are added to paper pulp to reduce paper weight and improve thermal insulation, then the thermal insulation properties are enhanced, but the substrate becomes prone to out-of-plane buckling under vertical stresses
Solution Approach 1:
The adhesive acts as an intermediary material between the substrates, containing the microspheres within the adhesive layer rather than incorporating them directly into the substrate structure. This positioning provides thermal insulation while the adhesive matrix supports the microspheres to prevent buckling
Solution Approach 2:
The microspheres are localized within the adhesive layer rather than distributed throughout the entire substrate structure. This local concentration provides thermal insulation at the adhesive-substrate interface without compromising the overall structural stability of the substrate
3Strength
If the amount of adhesive interposed between substrates is increased to improve the strength of low basis weight substrates, then the strength is enhanced, but the drying time is lengthened and manufacturing speed decreases
Solution Approach 1:
The patent changes the physical and chemical parameters of the adhesive by incorporating microspheres, which modify the adhesive's drying characteristics and curing behavior. This allows for reduced adhesive quantity while maintaining strength, or enables faster drying through improved water evaporation pathways created by the microsphere structure
Solution Approach 2:
The microsphere-containing adhesive creates a porous structure that facilitates faster water evaporation and drying. The interconnected voids provide pathways for moisture escape, reducing drying time and enabling higher manufacturing speeds without sacrificing bond strength
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 maintains thermal insulation and strength with reduced basis weight substrates, offering an environmentally friendly and economically viable solution for packaging, such as cups and cartons, with improved manufacturing efficiency.
Implementation Method 1
applying heat or radiation to expand the expandable microspheres
Implementation Method 2
the adhesive composition comprises (a) an emulsion-based polymer; (b) a plurality of microspheres, wherein the microspheres have a volume of about 10 to about 50 V/V % of the adhesive
Data Source
AI summary
The adhesive composition comprising emulsion polymers and microspheres and articles made therefrom are provided. The adhesive is particularly suitable for packages for consumer products that provide sufficient strength and thermal insulation while reducing the overall basis weight of the substrates.