Halogen-Free Crosslinked Resin Composition for Vehicle Wire Insulation
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Solution Overview
Problem
Halogen-free crosslinked resin compositions used in insulated wires and cables face challenges in achieving high flame retardancy, mechanical properties, oil resistance, and low temperature properties while preventing die residue and self-sticking issues, which are compromised by the use of polymers with high crystallinity or high vinyl acetate content.
Innovation Solution
A halogen-free crosslinked resin composition comprising ethylene vinyl acetate copolymer, acid modified polyolefin resin, silicone rubber, and metal hydroxide, with specific ratios and properties to enhance mechanical and thermal performance, and prevent adhesion and residue issues, applied to insulated wires and cables for vehicles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer having high crystallinity is used to achieve high oil resistance, then oil resistance is improved, but flexibility is lowered and wiring property worsens
Solution Approach 1:
The patent uses a composite material system consisting of EVA copolymer as the base polymer combined with specific additives (silicone rubber, metal hydroxide, crosslinking agent) to achieve both high oil resistance and maintained flexibility. The composite formulation allows the material to exhibit high oil resistance comparable to crystalline polymers while retaining the flexibility and wiring properties of amorphous polymers.
2Reliability
If EVA with large VA amount is used to achieve high oil resistance, then oil resistance is improved, but die residue and self-sticking occur due to high adhesion
Solution Approach 1:
The patent precisely controls the vinyl acetate content parameter within the range of 25-40 mass%, avoiding the high adhesion issues of high-VA EVA while maintaining adequate oil resistance. Additionally, the silicone rubber additive (0.1-5 parts by mass per 100 parts base polymer) modifies the surface properties to reduce adhesion and prevent die residue formation during extrusion molding.
Solution Approach 2:
Silicone rubber acts as an intermediary substance that modifies the surface characteristics of the EVA copolymer, reducing its adhesion properties and preventing die residue and self-sticking phenomena while allowing the bulk material to maintain its oil resistance properties.
3Reliability
If halogen-free flame retardant is fully filled to achieve high flame retardancy, then flame retardancy is improved, but mechanical properties and melt flow properties are lowered
Solution Approach 1:
The patent optimizes the filler content parameter, using 40-200 parts by mass of metal hydroxide per 100 parts base polymer, which provides sufficient flame retardancy while maintaining mechanical properties. The crosslinking agent (1-10 parts by mass) creates a three-dimensional network structure that reinforces the material, compensating for the mechanical property reduction caused by filler incorporation.
Solution Approach 2:
The patent creates a composite material system where metal hydroxide filler provides flame retardancy, silicone rubber provides flexibility and adhesion control, and crosslinking agents provide structural reinforcement. This multi-component composite allows achieving high flame retardancy while maintaining or even improving mechanical properties through the synergistic effects of the components.
4Temperature
If EVA with high VA amount is used to achieve excellent low temperature properties, then low temperature properties are improved, but Tg increases and low temperature property degradation occurs
Solution Approach 1:
The patent optimizes the vinyl acetate content within 25-40 mass%, balancing low temperature flexibility with glass transition temperature. The silicone rubber additive further modifies the material to maintain flexibility at low temperatures without causing excessive Tg increase, resolving the contradiction between low temperature performance and thermal properties.
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 composition achieves excellent flame retardancy, mechanical properties, oil resistance, and low temperature performance while preventing die residue and self-sticking, ensuring effective insulation and durability for vehicle applications.
Implementation Method 1
100 to 250 parts by mass of a metal hydroxide with respect to 100 parts by mass of the base polymer
Implementation Method 2
0.5 to 10 parts by mass of a silicone rubber with respect to 100 parts by mass of the base polymer
Implementation Method 3
a base polymer including as a main component (a) an ethylene vinyl acetate copolymer and (b) an acid modified polyolefin resin
Data Source
AI summary
A halogen-free crosslinked resin composition includes a base polymer including as a main component (a) an ethylene vinyl acetate copolymer and (b) an acid modified polyolefin resin having a differential scanning calorimetry glass transition temperature Tg of not higher than −55 degrees Celsius in a mass ratio (a):(b) of 70:30 to 100:0, the base polymer including 50 to 70% by mass of vinyl acetate, 0.5 to 10 parts by mass of a silicone rubber with respect to 100 parts by mass of the base polymer, and 100 to 250 parts by mass of a metal hydroxide with respect to 100 parts by mass of the base polymer.