Polyolefin Heat-Recoverable Article for Wire Harnesses
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Solution Overview
Problem
Existing heat-recoverable articles made from crosslinked polymers face issues with unstable diameter expansion, insufficient adhesiveness, and low shrinking rates, particularly at high and low temperatures, leading to potential tearing and breaking when used in a wide temperature environment.
Innovation Solution
A heat-recoverable article with a cylindrical shape, comprising a polyolefin-based resin base material layer that has specific thermal and mechanical properties, including a melting-point peak temperature between 115°C and 128°C, a heat of fusion between 80 J/g and 150 J/g, and storage moduli at 120°C and 180°C within defined ranges, enhancing manufacturability and adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing crosslinked polymers are used for heat-recoverable articles, then the articles can provide protection and insulation, but the expansion in diameter after molding is not stable
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer by introducing a long-chain branched component with specific branching frequency (5-50 branches per 1000 carbon atoms in the main chain) and molecular weight ratio (0.1-10 relative to linear component). This parameter modification enables both stable diameter expansion during manufacturing and the desired protection functions, resolving the contradiction between reliability and manufacturing precision.
2Ease of manufacture
If existing crosslinked polymers are used, then the articles can be manufactured, but adhesiveness to the object to be covered is insufficient
Solution Approach 1:
The patent modifies the polymer structure by incorporating long-chain branched components with specific characteristics (branching frequency of 5-50 per 1000 carbon atoms, molecular weight ratio of 0.1-10). These structural parameter changes enhance the polymer's adhesiveness to objects being covered while maintaining ease of manufacture through crosslinking, thus resolving the contradiction between manufacturability and reliability.
3Productivity
If existing crosslinked polymers are used, then the articles can be produced, but the shrinking rate is insufficient
Solution Approach 1:
The patent changes the molecular architecture parameters by introducing long-chain branched components with controlled branching frequency (5-50 per 1000 carbon atoms) and molecular weight ratios (0.1-10). These parameter modifications enable faster shrinking rates while maintaining production efficiency, as the branched structure facilitates more rapid conformational changes during heat recovery without compromising manufacturing productivity.
4Adaptability or versatility
If heat-recoverable articles are used in wide temperature environment from -60°C to 120°C, then versatility is improved, but tearing and breaking occur due to insufficient rigidity
Solution Approach 1:
The patent modifies the polymer's mechanical properties by incorporating long-chain branched components with specific branching frequencies (5-50 per 1000 carbon atoms) and molecular weight ratios (0.1-10). These parameter changes provide optimal rigidity that prevents tearing and breaking across the wide temperature range of -60°C to 120°C, resolving the contradiction between versatility and strength.
5Object-affected harmful factors
If heat shrinkage is performed at relatively low temperatures of 130°C or higher and 140°C or lower, then heat damage to objects is reduced, but shrinking time becomes excessively long
Solution Approach 1:
The patent changes the polymer's thermal response characteristics by introducing long-chain branched components with controlled branching frequency (5-50 per 1000 carbon atoms) and molecular weight ratios (0.1-10). These modifications enable the material to achieve rapid shrinking even at lower temperatures (130-140°C), reducing both heat damage to objects and shrinking time, thus resolving the contradiction between minimizing harmful effects and reducing time loss.
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 article exhibits improved manufacturability, shrinkability, and resistance to tearing and breaking across a wide temperature range, ensuring effective adhesiveness and reduced costs in applications like wire splices and harnesses.
Implementation Method 1
In the base material layer after being heated at 180°C for 2 minutes, a melting-point peak temperature is 115°C or higher and 128°C or lower
Implementation Method 2
when a connected portion between insulated electrical wires is covered with a heat-shrinkable tube and heating is performed, the heat-shrinkable tube shrinks so as to conform to the shape of the connected portion
Implementation Method 3
In the base material layer after being heated at 180°C for 2 minutes
Data Source
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AI summary
Provided is a heat-recoverable article having good manufacturability and good shrinkability at relatively low temperatures such as 130°C or higher and 140°C or lower, and being capable of effectively suppressing the occurrence of tearing and breaking and having good adhesiveness to an object to be covered even when used in a wide temperature environment from about -60°C to about 120°C. The heat-recoverable article according to the present invention has a cylindrical shape and includes a base material layer. The base material layer contains a polyolefin-based resin. In the base material layer after being heated at 180°C for 2 minutes, a melting-point peak temperature is 115°C or higher and 128°C or lower, a heat of fusion of a total resin component is 80 J/g or more and 150 J/g or less, a storage modulus at 120°C is 4 MPa or more, a gel fraction is 40% by mass or more and 80% by mass or less, and a storage modulus at 180°C is 0.5 MPa or more and less than 3.0 MPa. The polyolefin-based resin is preferably a mixture of a first polyolefin-based resin having a melting point of 125°C or higher and 135°C or lower and a second polyolefin-based resin having a melting point of lower than 125°C.