Laminated Insulated Wire for Rolling Stock
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Solution Overview
Problem
Insulated wires used in rolling stocks and electrical equipment face challenges in achieving a balance between high flame retardancy, mechanical characteristics, and processability, while also preventing the production of poisonous gases like cyanogen gas when burnt. Increasing the degree of cross-linking for improved mechanical characteristics impairs wire processability, and existing halogen-free materials may not adequately address these requirements.
Innovation Solution
A laminated insulation structure comprising an inner layer of thermoplastic resin with an aromatic ring and an outer layer of cross-linked polyolefin-based halogen-free flame retardant, where the inner layer is plastically deformable and the outer layer provides high flame retardancy and mechanical characteristics, and both layers are designed to prevent the production of poisonous gases when burnt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the degree of cross-linking is increased to improve mechanical characteristics, then the mechanical characteristics (cut-through properties, abrasion resistance) are improved, but the wire processability deteriorates due to increased rubber elasticity and decreased plastic deformability
Solution Approach 1:
The insulation layer is divided into two distinct layers: an inner layer made of thermoplastic resin that maintains plastic deformability for good wire processability, and an outer layer made of cross-linked halogen-free flame retardant material that provides high mechanical characteristics and flame retardancy. This segmentation allows each layer to optimize its properties without compromising the other.
Solution Approach 2:
Different regions of the insulation layer are assigned different material properties: the inner layer has high plasticity and processability, while the outer layer has high cross-linking density for mechanical strength. This local differentiation of material quality resolves the contradiction between processability and mechanical characteristics.
2Reliability
If halogen-free materials are used to reduce environmental burdens and improve safety, then flame retardancy and safety are improved, but the ability to achieve high mechanical characteristics while maintaining processability deteriorates
Solution Approach 1:
The patent uses a composite structure with two different material systems: the inner layer uses thermoplastic resin for processability, while the outer layer uses cross-linked halogen-free flame retardant material (such as polyolefin mixed with metal hydroxide) for flame retardancy and mechanical characteristics. This composite approach allows simultaneous achievement of safety and performance requirements.
3Strength
If the insulation layer is made highly cross-linked to improve cut-through properties and abrasion resistance, then mechanical characteristics are improved, but the plastic deformability decreases causing difficulty in wire processing
Solution Approach 1:
The insulation is segmented into an inner layer that retains plastic deformability for ease of wire processing and an outer layer that is highly cross-linked for cut-through resistance and abrasion resistance. This segmentation allows the outer layer to be optimized for mechanical strength without compromising the processability provided by the inner layer.
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 solution achieves a well-balanced combination of high flame retardancy, mechanical characteristics, and wire processability, while ensuring that no poisonous gases are produced during burning, thus enhancing the safety and performance of insulated wires and cables.
Implementation Method 1
strong chemical bonds are produced in polymer by cross-linking and impart rubber elasticity to the polymer
Implementation Method 2
insulated wires are required not to produce a poisonous gas harmful to human health, such as cyanogen gas or NOx gas, when burnt
Data Source
Figure 1
AI summary
An insulated wire includes a conductor, and an insulation layer provided around the conductor. The insulation layer includes an inner layer located on a conductor side and an outer layer provided around the inner layer. The inner layer includes a halogen-free resin composition including a base polymer (A). The outer layer includes a cross-linked body obtained by cross-linking a halogen-free flame-retardant resin composition including a base polymer (B) and a halogen-free flame retardant. The base polymer (A) includes a thermoplastic resin (a1) having an aromatic ring in a backbone chain. The base polymer (B) includes a polyolefin component. A thickness of the inner layer is not less than 0.03 mm and not more than 70% of a thickness of the insulation layer.