Polyolefin Foam Composition for Footwear Compression Set
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Solution Overview
Problem
Polyolefin foams used in footwear applications lack superior compression set and shrinkage resistance compared to poly(ethylene/vinyl acetate) foams, necessitating the development of foams with improved properties.
Innovation Solution
A foam composition comprising an olefin copolymer, an unneutralized carboxylated olefin copolymer, a blowing agent, and a crosslinking agent, with the carboxylated olefin copolymer present in amounts of 0.5 to 3 wt%, and no neutralized carboxylated ethylene copolymer, is used to create foams with enhanced cell sizes and crosslink densities, resulting in improved compression set and shrinkage resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If poly(ethylene/vinyl acetate) foams are used to achieve good cushioning properties, then cushioning performance is improved, but compression set and shrinkage resistance worsen at elevated temperatures
Solution Approach 1:
The patent changes the chemical composition parameters by using polyolefin base polymers with specific melting points (90-130°C) and incorporating carboxylated olefin copolymer in controlled amounts (0.5-3 wt%). It also adjusts crosslinking density through controlled crosslinking agent addition, transforming the material properties to achieve both cushioning and dimensional stability at elevated temperatures
Solution Approach 2:
The patent creates a composite foam system by combining polyolefin base polymer with carboxylated olefin copolymer and crosslinking agents. This composite approach integrates multiple functional components: the base polymer provides cushioning, the carboxylated copolymer enables crosslinking, and the crosslinking structure provides thermal stability, resolving the contradiction between softness and thermal resistance
2Reliability
If crosslinking density is increased to improve compression set resistance, then dimensional stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs self-service by using carboxylated olefin copolymer that automatically provides crosslinking functionality within the foam system. The carboxylic acid groups in the copolymer self-assemble and crosslink with crosslinking agents during foam processing, eliminating the need for separate crosslinking equipment or complex multi-step procedures, thus achieving high crosslinking density with simple manufacturing
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 foam composition achieves lower compression set and shrinkage, providing superior properties for footwear applications by maintaining a fine cell size and enhanced mechanical strength.
Implementation Method 1
heating the foam composition to activate the blowing agent to form a foam
Implementation Method 2
crosslinking the foam
Data Source
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AI summary
Disclosed herein is a foam composition comprising an olefin copolymer that comprises ethylene and an α-olefin or propylene and an α-olefin; an unneutralized carboxylated olefin copolymer; a crosslinking agent; and a blowing agent; where the foam composition is substantially free from neutralized carboxylated ethylene copolymer. Disclosed herein too is a method of manufacturing a foam composition comprising blending together an olefin copolymer that comprises ethylene and an α-olefin or propylene and an α-olefin; an unneutralized carboxylated olefin copolymer; a crosslinking agent; and a blowing agent to form the foam composition; where the foam composition is substantially free from neutralized carboxylated ethylene copolymer; heating the foam composition to activate the blowing agent to form a foam; and crosslinking the foam.