Reinforcing Sheet for Resin Molded Articles

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Solution Overview

Problem

Conventional methods for reinforcing resin molded articles often result in surface damage due to sink marks and require high temperatures, which can deteriorate the resin, leading to reduced reinforcement over time.

Innovation Solution

A reinforcing sheet with a constraining layer and a thermally adhesive reinforcing layer, using a hydrogenated polymer and tackifier, is applied at a lower temperature (80°C) to improve bending strength and maintain adhesion retention even under high-temperature conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rib is integrally molded with the resin plate to reinforce it, then the reinforcement strength is improved, but sink marks occur on the surface causing appearance damage

Engineering Contradiction:

Improvereinforcement strengthVSAvoidsurface appearance

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The reinforcement structure is segmented into two separate components: the resin plate and the reinforcing sheet. The reinforcing sheet is attached to the resin plate as a separate element rather than being integrally molded, thus avoiding sink marks on the surface while maintaining reinforcement strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A reinforcing sheet serves as an intermediary element between the resin plate and the external environment. This sheet provides the necessary reinforcement without requiring integral molding, thereby preventing surface defects while achieving the desired structural strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If a reinforcing sheet is heated at 160 to 200°C to cure the foamable composition, then the reinforcement force is improved, but the resin plate is deteriorated or melted

Engineering Contradiction:

Improvereinforcement forceVSAvoidheating temperature

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The curing temperature parameter is changed from the conventional 160-200°C range to a lower temperature range of 80-100°C. This parameter change allows the foamable composition to cure effectively without exceeding the heat resistance of the resin plate, thus maintaining both reinforcement force and material integrity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention adopts a reinforcing sheet structure similar to steel plate reinforcement but modifies the material composition and curing conditions to suit thermoplastic resin plates. This copied approach with adaptations enables low-temperature curing that preserves the resin plate while achieving adequate reinforcement.

Inventive Principle:

Principle #26Copying

3Reliability

If the reinforcing sheet is placed under high temperature atmosphere for long hours, then the adhesion is maintained initially, but the reinforcement force reduces over time

Engineering Contradiction:

Improveadhesion retentionVSAvoidservice duration under high temperature

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The adhesive composition maintains continuous effective adhesion under high temperature conditions through its specific formulation. The adhesive continues to provide bonding strength over extended periods at temperatures up to 100°C, preventing the reinforcement force reduction that occurs with conventional adhesives.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The reinforcing sheet uses a composite structure combining a foamable composition with specific adhesive properties. This composite material formulation enables the sheet to maintain both its structural reinforcement function and adhesive bonding under prolonged high temperature exposure, preventing degradation over time.

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 reinforces resin molded articles without damaging their appearance, maintains adhesion at elevated temperatures, and prevents reduction in reinforcement force over time, while being lightweight and cost-effective.

Implementation Method 1

heating at 80°C for 10 minutes

Methodology Applied

Scientific EffectThermal activation of adhesive: Heating

Implementation Method 2

adhesive composition containing a hydrogenated polymer of a monomer containing conjugated dienes

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2548737B1Reinforcing sheet for resin molded article, reinforced structure of resin molded article, and reinforcing method

Publication Date: 2020.01.08 NITTO DENKO CORP

Figure 1(a)~2

AI summary

A reinforcing sheet for a resin molded article includes a constraining layer and a reinforcing layer laminated on the constraining layer. When the reinforcing sheet for a resin molded article is attached to a polypropylene plate having a thickness of 2.0 mm and is heated at 80°C for 10 minutes, the bending strength at a displacement of 1 mm of the resulting sheet after the heating is 3 N or more and the maximum bending strength thereof is 30 N or more, and a high-temperature adhesion retention ratio R as determined by the following formula is 80 % or more. High-temperature adhesion retention ratio R=Adhesion forceA1000⁢hafter heating at100⁢°C for1000hours/Adhesive forceA1⁢hafter heating at100⁢°C for1hour×100