Adhesive Resin Composition for Moist-Heat-Resistant Cable Laminates
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Solution Overview
Problem
Existing adhesive resin compositions used in flexible flat cables fail to provide adequate moist heat resistance and adhesion to conductors in high temperature and high humidity environments, and require cross-linking processes for higher temperature ratings, which are costly and reduce productivity.
Innovation Solution
An adhesive resin composition comprising acid-modified polypropylene-based resin, polypropylene-based resin, and ethylene vinyl acetate copolymer, with specific flame retardants, that retains adhesive properties and meets higher temperature ratings without cross-linking, using components like maleic anhydride-modified polypropylene and ethylene vinyl acetate copolymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyester-based resin composition is used as adhesive resin composition, then it provides basic adhesion to conductors, but it gives insufficient moist heat resistance and adhesion strength deteriorates in high temperature and high humidity environment
Solution Approach 1:
The patent uses a composite resin composition comprising polypropylene-based resin (50-90 mass%), ethylene vinyl acetate copolymer (5-40 mass%), and flame retardant (3-40 mass%). This composite structure combines the heat resistance of polypropylene with the adhesion properties of EVOH, creating a material that maintains both strong adhesion and excellent moist heat resistance in high temperature humid environments.
Solution Approach 2:
The patent optimizes specific parameters including the mass ratios of resin components, the vinyl acetate content (10-40 mol%) in EVOH, and the flame retardant content (3-40 mass%). By carefully controlling these parameters, the composition achieves UL 125°C certification while maintaining adhesion strength after 500 hours of 85°C/85%RH storage, resolving the contradiction between heat resistance and adhesion retention.
2Temperature
If cross-linking steps (electron beam irradiation or aqueous cross-linking) are performed to achieve higher temperature rating, then temperature rating certification is obtained, but productivity decreases and costs increase
Solution Approach 1:
The patent extracts and eliminates the cross-linking process steps from the manufacturing workflow. By formulating a resin composition that inherently achieves UL 125°C certification through its component selection and ratios (polypropylene-based resin combined with EVOH and flame retardant), the patent removes the need for electron beam irradiation or aqueous cross-linking steps, thereby maintaining high productivity and low costs while achieving the desired temperature rating.
Solution Approach 2:
The resin composition itself provides the heat resistance properties needed for UL 125°C certification through its intrinsic material properties rather than requiring external cross-linking treatment. The polypropylene-based resin with optimized EVOH and flame retardant content self-achieves the temperature rating requirement, eliminating the need for additional processing steps.
3Ease of operation
If conventional adhesive resin compositions are used in high temperature and high humidity environment, then basic cable function is maintained, but laminate peeling occurs and conductor exposure happens in extreme cases
Solution Approach 1:
The patent employs a composite material system where polypropylene-based resin provides heat resistance, ethylene vinyl acetate copolymer provides adhesion to conductors, and flame retardant ensures safety. This composite structure maintains laminate integrity and prevents peeling even after 500 hours of storage at 85°C and 85% relative humidity, ensuring both cable functionality and adhesion stability in harsh environments.
Solution Approach 2:
The patent adjusts critical parameters including the mass percentage of each component (polypropylene 50-90%, EVOH 5-40%, flame retardant 3-40%), the vinyl acetate content (10-40 mol%), and the molecular weight characteristics. These parameter optimizations ensure the adhesive layer maintains its bonding strength and prevents laminate peeling under high temperature and humidity conditions while preserving cable functionality.
Data Source
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AI summary
Provided is adhesive resin compositions comprising (A) 30 to 70% by mass of an acid-modified polypropylene-based resin; (B) 20 to 60% by mass of a polypropylene-based resin; and (C) 2 to 20% by mass of a copolymer of ethylene and one or more kinds of comonomers selected from the group consisting of vinyl acetate, alkyl methacrylate, and alkyl acrylate, with the proviso that the sum of the percentages of the above component (A), the above component (B), and the above component (C) is 100% by mass.