Bead Foam Density Ratio for Resin Composite Strength

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Solution Overview

Problem

The challenge is to produce a resin composite with both high strength and lightness while maintaining a good appearance, as existing methods often result in surface voids and fiber exposure due to weak compression strength of bead expanded articles.

Innovation Solution

Increasing the density of bead expanded articles within a specific range of 10% compression stress to density ratio, combined with high air permeability resistance and thermal fusion rate, allows for the production of resin composites with improved strength, lightness, and appearance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the density of bead expanded article is increased to improve compression strength, then compression strength is improved, but mass increases unnecessarily

Engineering Contradiction:
Improvecompression strengthVSAvoidmass
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The invention changes the physical and chemical parameters of the bead expanded article by controlling the polycarbonate resin composition, blowing agent content, and expansion conditions to achieve a specific density range (0.05-0.20 g/cm³) and compression strength range (10% compression stress/density ratio of 5-20 MPa·cm³/g), resolving the contradiction between compression strength and mass

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses composite materials by combining polycarbonate-based resin with specific blowing agents and optional additives to create a bead expanded article that achieves both lightness and sufficient compression strength through material composition optimization rather than simple density increase

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If pressure is applied during lamination of fiber-reinforced resin material, then lamination is achieved, but surface appearance deteriorates due to voids and fiber exposure

Engineering Contradiction:
Improvelamination processVSAvoidsurface appearance
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention applies beforehand cushioning by pre-expanding the beads to a controlled density and incorporating expansion control mechanisms that prevent excessive expansion during lamination, thereby cushioning against the harmful effect of surface voids and fiber exposure while still allowing proper lamination

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 approach results in resin composites that are excellent in strength, lightness, and appearance, with enhanced surface smoothness and desired thickness, avoiding surface imperfections and resin depletion.

Implementation Method 1

heating the expandable particles to prepare pre-expanded particles

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

a plurality of expanded particles which are mutually thermally fused

Methodology Applied
Scientific EffectThermal fusion:

Implementation Method 3

impregnating a thermoplastic resin composition containing a polycarbonate-based resin having an aromatic skeleton as a main component with a blowing agent to prepare expandable particles; preparing pre-expanded particles by heating the expandable particles

Methodology Applied
Scientific EffectGas generation from heating: Boiling

Implementation Method 4

filling a mold with the pre-expanded particles to which the internal pressure is applied and introducing steam to the mold to secondarily expand the pre-expanded particles

Methodology Applied
Scientific EffectPressure differential expansion: Pressure Gradient

Data Source

PatentEP3677624B1Bead foam, resin composite provided with same, and method for producing bead foam
Publication Date: 2022.05.18 SEKISUI PLASTICS CO LTD
  • EP3677624B1 patent drawingFigure 1~2
  • EP3677624B1 patent drawingFigure 3
  • EP3677624B1 patent drawing

AI summary

A bead expanded article containing a plurality of expanded particles, in which the bead expanded article has a property that a value obtained by dividing a 10% compression stress (MPa) of the bead expanded article by a density (g/cm3) is 9.0 (MPa·cm3/g) or more.