Polyamide Resin Expanded Sheet Moisture Control

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Solution Overview

Problem

Resin expanded molded articles produced from polyamide-based resin sheets face challenges in maintaining shape stability due to high water absorption rates, leading to dimensional changes after outer shape processing.

Innovation Solution

The method involves pre-heating and thermally molding a polyamide-based resin expanded sheet with a moisture content of 30% or more at 23°C and 60% relative humidity to form a three-dimensional shape, which suppresses water absorption and subsequent shape changes during the production of resin expanded molded articles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a polyamide-based resin expanded sheet is used as a raw material, then the resin expanded molded article has high strength and heat resistance, but the water absorption rate increases causing dimensional changes after outer shape processing

Engineering Contradiction:
Improvemechanical strengthVSAvoiddimensional stability
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by pre-heating the polyamide-based resin expanded sheet before outer shape processing. This pre-heating step prepares the material in advance to resist water absorption during subsequent processing, thereby preventing dimensional changes while maintaining the high strength characteristics of polyamide resin.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the temperature parameter by pre-heating the resin expanded sheet to a specific temperature range before processing. This parameter change modifies the material's physical properties to reduce its tendency to absorb water and undergo dimensional changes during outer shape processing, while preserving the mechanical strength benefits of polyamide.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the resin expanded sheet is subjected to outer shape processing in a dried state, then the processing efficiency is improved, but the water absorption rate increases after processing causing shape changes

Engineering Contradiction:
Improveprocessing efficiencyVSAvoidshape stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent performs pre-heating as a preliminary action before outer shape processing. This step prepares the resin expanded sheet in advance to maintain shape stability during processing, allowing efficient processing while preventing subsequent dimensional changes due to water absorption.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The pre-heating step serves as a preliminary anti-action against water absorption. By heating the sheet before processing, the patent creates a state that resists water uptake during and after processing, thereby preventing shape changes while maintaining processing efficiency.

Inventive Principle:
Principle #9Preliminary anti-action

3Ease of manufacture

If thermal molding is performed on polyamide-based resin expanded sheet, then the three-dimensional shape can be formed, but the high water absorption rate causes dimensional changes in the final product

Engineering Contradiction:
ImprovemoldabilityVSAvoiddimensional stability
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent applies pre-heating as a preliminary action before thermal molding. This prepares the polyamide-based resin expanded sheet to maintain dimensional stability during the molding process and after cooling, allowing successful formation of three-dimensional shapes while preventing water-induced dimensional changes.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent modifies the temperature parameter by pre-heating the sheet to a specific range before thermal molding. This parameter change enables the material to resist water absorption during molding and cooling, ensuring dimensional stability of the final three-dimensional product while maintaining ease of manufacture.

Inventive Principle:
Principle #35Parameter changes

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

This approach results in resin expanded molded articles with minimal dimensional changes, enhancing stability and mechanical strength, suitable for applications requiring dimensional stability and resistance to heat and chemicals.

Implementation Method 1

a water absorption rate is easily increased after outer shape processing, to generate change in an outer shape in the resin expanded molded article

Methodology Applied
Scientific EffectWater absorption: Absorption (physical)

Implementation Method 2

a pre-heating step of heating to soften a resin expanded sheet with a radiation heater or the like

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP3202829B1Use of a resin expanded sheet, and method for producing a resin expanded molded article
Publication Date: 2020.01.29 SEKISUI PLASTICS CO LTD
  • EP3202829B1 patent drawingFigure 1
  • EP3202829B1 patent drawingFigure 2a~2b
  • EP3202829B1 patent drawingFigure 3a~3b

AI summary

In outer shape processing of a resin expanded sheet having a resin expanded layer including a polyamide-based resin composition, the outer shape processing is carried out while allowing a specified amount or more of moisture to be contained in the resin expanded layer.