Polyolefin Resin Foamability and Extrusion Stability

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Solution Overview

Problem

Existing foamed laminates and foamed papers lack sufficient foamability, leading to inadequate foaming degree and stability issues in extrusion lamination, which affects the appearance and workability of the foamed layer.

Innovation Solution

A resin for foamable laminates is developed, comprising a polyolefin resin with specific melt flow rate (MFR) and density, and a thermoplastic resin layer with a specific melting point, where the polyolefin resin is formed on one side of a paper-base substrate and the thermoplastic resin on the other, to enhance foamability and produce uniform, high-expansion foamed cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If MFR is increased to improve foamability, then the foamability is improved, but the outward appearance of the foamed layer worsens and the workability in extrusion lamination becomes unstable

Engineering Contradiction:

ImprovefoamabilityVSAvoidoutward appearance of foamed layer

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by precisely controlling the MFR of the polyolefin resin within the range of 0.1 to 30 g/10 min and the density within 0.905 to 0.940 g/cm³. This optimization of physical parameters enables the resin to achieve sufficient foamability while maintaining stable extrusion lamination workability and good outward appearance of the foamed layer, thereby resolving the contradiction between improved foamability and manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If MFR is increased to improve foamability, then the foamability is improved, but the workability in extrusion lamination becomes unstable

Engineering Contradiction:

ImprovefoamabilityVSAvoidworkability in extrusion lamination

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent resolves this contradiction by optimizing the MFR parameter to a specific range (0.1 to 30 g/10 min) that balances foamability with extrusion lamination workability. This controlled parameter change ensures that the resin has sufficient foamability while maintaining stable and easy workability during the extrusion lamination process.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by stationary object

If a foamed layer is formed on paper substrate, then heat insulation performance is improved, but the foaming degree is insufficient

Engineering Contradiction:

Improveheat insulation performanceVSAvoidfoaming degree

Core Design Contradiction:

Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent achieves sufficient foaming degree and good heat insulation performance by optimizing the polyolefin resin parameters (MFR: 0.1 to 30 g/10 min, density: 0.905 to 0.940 g/cm³) and controlling the heating conditions. These parameter changes enable the formation of a foamed layer with adequate expansion ratio and cell structure, ensuring both high foaming degree and effective heat insulation.

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

The solution results in a foamable laminate with improved workability and producibility, achieving high expansion ratios and uniform foamed cells with a foamed layer height of at least 370 µm, enhancing the heat-insulating properties and appearance of the foamed paper and containers.

Implementation Method 1

wherein the melting point (Tm(A)) of the polyolefin resin (A) and the melting point (Tm(B)) of the thermoplastic resin (B) satisfy relational formula (4)

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

forming, on the other side of the substrate, a layer (B) of a thermoplastic resin having a specific melting point for retaining the vapor released from the substrate

Methodology Applied

Scientific EffectVapor pressure: Vapour Pressure

Implementation Method 3

when the layer (A) is heated, it gives a foamed paper having a good appearance of the foamed layer

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentEP2223802B1Resin for foamable layered product, foamable layered product, and foamed converted paper and heat-insulating container both obtained from the same

Publication Date: 2015.09.09 JAPAN POLYETHYLENE CORP

Figure 1~2

AI summary

Provided are a resin for foamable laminate which, upon heating, gives foamed cells having a sufficient height (foamed layer), a foamable laminate, a foamed paper having a foamed layer, and a heat-insulating container such as cup comprising it. The resin for foamable laminate provided here is for forming a foamable polyolefin resin layer (A) on at least one side of a paper-base substrate, and contains a polyolefin resin (A) having the following properties (A1) to (A3): (A1) the MFR is from 1 to 50 g/10 min, (A2) the density is at least 0.880 g/cm3, (A3) the MFR and the memory effect (ME) satisfy the following relational formula (formula 1): -0.467×LnMFR+3.20≤ME