EVA Thermoplastic Footwear Compounds Softness
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Solution Overview
Problem
Traditional materials like PVC and natural rubber used in footwear manufacturing compromise on properties such as flexibility, grip, abrasion resistance, and chemical resistance, while EVA copolymers, despite offering superior mechanical and low-temperature properties, are too hard for footwear applications due to limited plasticizer absorption.
Innovation Solution
Formulating polymer compositions with ethylene vinyl acetate copolymers (30-70 wt%), rubber (5-30 wt%), and plasticizers (10-40 wt%), with a rubber to plasticizer weight ratio of 1:1 to 1:5, to create thermoplastic articles that are flexible, durable, and resistant to abrasion and chemicals, suitable for footwear applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVA copolymers are used in footwear applications, then mechanical properties and low-temperature performance are improved, but the material is too hard for comfortable footwear use
Solution Approach 1:
The patent creates a composite material system combining EVA copolymer with rubber particles and plasticizers. The rubber phase (5-30 wt%) provides flexibility and softness, while the plasticizer (10-40 wt%) further reduces hardness. This composite approach allows the material to maintain the superior mechanical properties of EVA while incorporating the softness and flexibility characteristics of rubber, resolving the contradiction between durability and comfort.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the EVA copolymer by controlling the vinyl acetate content (10-40 mol%) and incorporating specific amounts of plasticizers and rubbers. These parameter changes transform the material from a hard, rigid structure to a softer, more flexible composition suitable for footwear, while maintaining the core mechanical advantages of EVA.
2Ease of operation
If traditional rubber materials are used, then flexibility and grip are improved, but chemical resistance towards oil and hydrocarbons deteriorates
Solution Approach 1:
The patent formulates a composite where rubber particles (5-30 wt%) dispersed in the EVA matrix provide flexibility and grip characteristics, while the continuous EVA phase maintains chemical resistance to oil and hydrocarbons. This composite structure allows each component to contribute its superior properties without compromising the other, as the rubber is dispersed as discrete particles rather than forming a continuous phase vulnerable to chemical degradation.
3Reliability
If PVC is used, then chemical resistance is improved, but flexibility, grip, and abrasion resistance deteriorate
Solution Approach 1:
The patent creates an EVA-based composite material that replaces PVC while maintaining its advantages. The EVA copolymer matrix provides inherent chemical resistance similar to or better than PVC, while the incorporated rubber particles (5-30 wt%) significantly improve abrasion resistance, flexibility, and grip. This composite approach eliminates PVC's deficiencies in mechanical performance while preserving its chemical resistance profile.
4Ease of operation
If plasticizer content is increased to soften EVA, then softness is improved, but plasticizer absorption capacity is limited
Solution Approach 1:
The patent employs a dual-softening strategy using both plasticizers (10-40 wt%) and rubber particles (5-30 wt%). The rubber phase acts as an additional softening agent that can be incorporated in significant quantities without the same absorption limitations as plasticizers. This composite approach allows for greater overall softening capacity by distributing the softening function between two different components, each with its own mechanisms and capacity limits.
Data Source
AI summary
Compositions may include a polymer composition prepared from an ethylene vinyl acetate copolymer, a rubber, and a plasticizer. Compositions may further comprise other components, such as a curing agent and a blowing agent. Articles may include a polymer composition prepared from an ethylene vinyl acetate copolymer, a rubber, and a plasticizer. Methods may include mixing an ethylene vinyl acetate copolymer, a rubber, and a plasticizer; and extruding the mixture thereof.