Water-Crosslinkable Polyolefin Wire Coating Flame Retardancy
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Solution Overview
Problem
Conventional water-crosslinkable resin compositions for wire coating in automobiles require high amounts of fillers for flame retardancy, leading to oxidation degradation and increased production costs, and electron irradiation crosslinking is expensive and inefficient.
Innovation Solution
A composition for wire coating using water-crosslinkable polyolefin modified with silane coupling agents, unmodified polyolefin, modified polyolefin with functional groups, bromine flame retardants, cross-linking catalysts, phenolic antioxidants, and zinc-based additives, which eliminates the need for excessive fillers and electron irradiation, enhancing heat resistance and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a great amount of filler such as magnesium hydroxide is added to satisfy flame retardancy, then flame retardancy is improved, but oxidation degradation is promoted and heat resistance is degraded
Solution Approach 1:
The invention changes the chemical composition parameters by using bromine-based flame retardant instead of magnesium hydroxide filler, and by incorporating silane-modified polyolefin with specific gel content (30-80%). This parameter change achieves flame retardancy without the oxidation degradation caused by large amounts of magnesium hydroxide, thereby maintaining heat resistance
Solution Approach 2:
The invention uses a composite material system consisting of silane-modified polyolefin (A), polyolefin resin (B), bromine-based flame retardant (D), and specific additives (E, F, G). This composite approach replaces the conventional single-material approach of using large amounts of magnesium hydroxide filler, achieving both flame retardancy and heat resistance through synergistic material combinations
2Temperature
If electron irradiation crosslinking is used to achieve high heat resistance, then heat resistance is improved, but production cost increases due to expensive crosslinking devices and facilities
Solution Approach 1:
The invention replaces the electron irradiation crosslinking system with a chemical crosslinking system using silane coupling agents and crosslinking catalysts. This substitution eliminates the need for expensive electron irradiation equipment while achieving comparable or superior heat resistance through water-crosslinking or heat-crosslinking processes that use conventional, cost-effective facilities
Solution Approach 2:
The invention changes the crosslinking method parameter from physical (electron irradiation) to chemical (silane coupling agent with crosslinking catalyst). This parameter change enables crosslinking to be performed using inexpensive water-crosslinking facilities or conventional heat treatment, dramatically reducing production costs while maintaining high heat resistance
3Ease of manufacture
If water-crosslinking is used to reduce production cost, then production cost is reduced, but water in the air promotes unintended crosslinking during heat molding
Solution Approach 1:
The invention applies preliminary protection by adding phenolic antioxidants (F) and zinc-based additives (G) before crosslinking occurs. These additives prevent premature oxidation and unintended crosslinking during heat molding by scavenging free radicals and stabilizing the polymer matrix, thereby controlling the crosslinking process even in the presence of moisture
Solution Approach 2:
The invention uses silane coupling agents as intermediaries that first graft onto the polyolefin chains without causing immediate crosslinking. The actual crosslinking is then controlled by adding crosslinking catalysts (E) under specific conditions, allowing the process to proceed in a controlled manner rather than occurring prematurely due to atmospheric moisture
4Stability of the object's composition
If a great amount of filler is added to the master batch to prevent unintended crosslinking, then crosslinking control is improved, but viscosity increases and dispersion becomes unfavorable
Solution Approach 1:
The invention changes the formulation parameters by using bromine-based flame retardant (D) in controlled amounts (5-50 parts by mass per 100 parts of total resin) instead of large amounts of magnesium hydroxide filler. This parameter change maintains crosslinking control through chemical means rather than relying on filler quantity, thereby avoiding viscosity increase and ensuring favorable dispersion
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 provides excellent heat resistance and mechanical properties without the need for expensive fillers or electron irradiation, improving productivity and reducing costs while maintaining flame retardancy.
Implementation Method 1
water-crosslinkable polyolefin (A) that defines polyolefin modified by a silane coupling agent
Implementation Method 2
crosslinking a silane graftmer (A component) and a catalyst master batch (B component)
Implementation Method 3
the flame retardant (D) contains (D1) a bromine flame retardant
Implementation Method 4
a phenolic antioxidant (F)
Implementation Method 5
either one of (G1) a zinc sulfide, and (G2) a zinc oxide and (G3) an imidazole compound
Data Source
AI summary
A composition for a wire coating member having flame retardancy that is heat resistant and productive without using electron irradiation crosslinking, and an insulated wire and a wiring harness having the same. The insulated wire includes a wire coating member containing the composition for the wire coating member that contains water-crosslinkable polyolefin containing polyolefin that is modified by a silane coupling agent, unmodified polyolefin, modified polyolefin that is modified by a functional group, a bromine flame retardant, a cross-linking catalyst, a phenolic antioxidant, and either one of a zinc sulfide, and a zinc oxide and an imidazole compound. The insulated wire is prepared by extrusion-coating a conductor with the composition to form the wire coating member around the conductor, and the wire coating member is water-crosslinked.