Heat-Recoverable Adhesive Layer for PVC Wire Protection

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Solution Overview

Problem

Multilayered heat-recoverable articles used to protect PVC insulated wires face issues with adhesive layer deterioration and flow, leading to loss of adhesion and protection when exposed to heat and current, causing cracks in the PVC layer and compromising waterproofness.

Innovation Solution

Incorporating a thermoplastic resin and a viscosity characteristics modifier, such as silica, organically treated layered silicate, and deterioration inhibitors, into the adhesive layer to prevent flow and deterioration at elevated temperatures, ensuring adhesion and protection of PVC insulated wires.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a multilayered heat-recoverable article with an adhesive layer is used to protect PVC insulated wires, then adhesion and protection are improved, but the adhesive layer flows and deteriorates at elevated temperatures, causing loss of adhesion

Engineering Contradiction:

ImproveadhesionVSAvoidadhesive layer stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical composition parameters of the adhesive layer by incorporating specific additives (silica, organically treated layered silicate, and deterioration inhibitors) to change its thermal and rheological properties. This allows the adhesive to maintain its adhesion properties while resisting flow and deterioration at elevated temperatures up to 135°C.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The adhesive layer is formulated as a composite material combining a thermoplastic resin base with dispersed inorganic particles (silica or layered silicate) and chemical additives. This composite structure provides both the adhesion characteristics of the polymer and the thermal stability, viscosity control, and deterioration resistance of the inorganic components and inhibitors.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the adhesive layer is heated to fluidize for adhesion, then adhesion to the wire surface is improved, but the adhesive layer flows out from the heat-shrinkable base material layer, causing loss of protection

Engineering Contradiction:

ImproveadhesionVSAvoidadhesive layer loss

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The viscosity characteristics modifier components (silica, layered silicate) fundamentally change the rheological parameters of the adhesive layer, creating a thixotropic or shear-thinning behavior that allows controlled flow during heating while preventing excessive drainage and loss of material from the application area.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The inorganic particles (silica, layered silicate) act as intermediary substances within the adhesive matrix, providing structural support and viscosity control that mediates between the need for flow during application and the need to retain material in place. These particles create a network structure that limits flow while allowing sufficient mobility for adhesion.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the multilayered heat-recoverable article is used to cover insulated electrical wires, then protection from external force and moisture is improved, but cracks occur in the polyvinyl chloride layer under heating conditions, compromising protection

Engineering Contradiction:

ImproveprotectionVSAvoidPVC layer cracking

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The deterioration inhibitor components chemically interact with or neutralize the factors causing PVC degradation at elevated temperatures, changing the chemical environment to prevent crack formation. This allows the protective function to be maintained even under prolonged heating conditions at 135°C.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful effect of heat exposure that would normally cause PVC deterioration and cracking into a beneficial condition by using the heat-recoverable article's controlled adhesion and protection mechanisms. The heat that would cause harm is instead managed to provide controlled shrinkage and adhesion while the inhibitors prevent the harmful chemical degradation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If the adhesive layer is made more flowable for better adhesion, then adhesion is improved, but the adhesive layer deteriorates faster at elevated temperatures, reducing long-term protection

Engineering Contradiction:

ImproveadhesionVSAvoidadhesive layer durability

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent optimizes the chemical composition parameters of the adhesive layer by incorporating specific ratios of thermoplastic resin, viscosity modifiers, and deterioration inhibitors. This creates a balanced system where the adhesive maintains sufficient flowability for good adhesion while the inhibitors extend the service life by preventing thermal deterioration.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Inventive Principle:

Principle #40Composite materials

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 effectively suppresses adhesive layer flow and deterioration, maintaining adhesion and waterproofness of PVC insulated wires under heat and current conditions, preventing cracks and ensuring long-term protection.

Implementation Method 1

by performing heating with an adherend being covered with the multilayered heat-recoverable article, heat shrinkage of the heat-shrinkable base material layer occurs, and at the same time, the adhesive layer is fluidized

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

when a joint between insulated electrical wires is covered with a heat-shrinkable tube and heating is performed, the heat-shrinkable tube shrinks, conforms to the shape of the joint, and adheres thereto

Methodology Applied

Scientific EffectHeat shrinkage: Thermal Contraction

Data Source

PatentUS9525281B2Multilayered heat-recoverable article, wire splice, and wire harness

Publication Date: 2016.12.20 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

A multilayered heat-recoverable article 1 includes a base material layer 10 and an adhesive layer 11 disposed on an inner side of the base material layer 10. The adhesive layer 11 does not flow at a temperature of 135° C. and includes a thermoplastic resin and a viscosity characteristics modifier composed of at least one selected from the group consisting of silica, an organically treated layered silicate, and a deterioration inhibitor. In the case where the multilayered heat-recoverable article 1 is used to cover an insulated electrical wire which includes a conductor and a polyvinyl chloride layer provided on the outer periphery thereof, cracks do not occur in the polyvinyl chloride layer under heating conditions at 135° C. for 200 hours.