Thin Wall Cable Insulation Using HALS for Heat Ageing Resistance
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Solution Overview
Problem
Current insulation materials for wires and cables face challenges in maintaining thermal stability at high temperatures, particularly in thin wall configurations, where they must withstand heat ageing tests at 125°C or more without degrading, as existing additives like Vanox ZMTI are inadequate for preventing heat ageing in these conditions.
Innovation Solution
A composition comprising low melting point polyethylene copolymers, specifically ethylene vinyl acetate copolymers, combined with a hindered amine light stabiliser (HALS) such as Sabostab UV 94, and a halogen-free flame retardant like hydrated inorganic fillers, which improves thermal ageing properties and resistance to heat-induced degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the insulation layer thickness is reduced to 0.25 mm to meet thin wall wire requirements, then the wire satisfies modern design constraints, but the material becomes significantly more vulnerable to heat ageing degradation
Solution Approach 1:
The patent changes the chemical composition parameter of the insulation material by incorporating HALS antioxidants, which provide enhanced thermal stability. This enables thin wall wires with 0.25 mm insulation thickness to maintain adequate heat ageing resistance despite the reduced material thickness, satisfying both design constraints and reliability requirements
Solution Approach 2:
The HALS antioxidant acts as an intermediary protective agent in the thin insulation layer. It mediates between the polyethylene copolymer and the harsh thermal environment, preventing oxidative degradation and enabling the thin wall construction to pass ISO 6722 heat ageing tests
2Reliability
If high concentrations of conventional antioxidants are used to improve heat ageing resistance, then thermal stability improves, but the cost and complexity of the additive package increases
Solution Approach 1:
The patent changes the type parameter of the antioxidant from conventional options to HALS, which provides superior thermal stability at lower concentrations. This simplifies the additive package by reducing the number and variety of additives needed while achieving the required performance level
Solution Approach 2:
The patent employs HALS as a highly efficient antioxidant that provides long-lasting protection with minimal dosage. This replaces the need for multiple conventional antioxidants, effectively reducing the additive package to a simpler, more cost-effective solution with comparable or superior performance
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 proposed solution significantly enhances the heat ageing performance of wire and cable insulation, allowing them to pass stringent ISO 6722 tests at 125°C for 3000 hours or 150°C for 240 hours, outperforming comparative examples and minimizing the need for high antioxidant concentrations.
Implementation Method 1
the inclusion of a hindered amine light stabiliser (HALS) such as Sabostab UV 94 provides superior thermo-oxidative stability for thin wall cables
Implementation Method 2
the HALS motif provides improved thermal ageing properties, in particular when combined with antioxidants
Data Source
AI summary
The present invention relates to a wire or cable comprising a conductor coated with an insulation composition, wherein said insulation composition comprises: i) a polyethylene copolymer having a melting point of 105° C. or less; and ii) a hindered amine light stabiliser (HALS) comprising at least one 2,2,6,6-tetramethyl-piperidinyl group present in an amount of 0.5 to 1.5 wt %.