Multilayer Polypropylene Sheet Structure for Higher Rigidity

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Solution Overview

Problem

Existing multilayer polypropylene sheets, while exhibiting excellent rigidity, have limitations in further enhancing this property, restricting their application expansion.

Innovation Solution

A polypropylene multilayer sheet is designed with two types of biaxially oriented polymer layers having different contents of an inorganic filler alternately laminated, forming a multilayer structure with specific thickness and melting point relationships to enhance rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the thickness of existing multilayer polypropylene sheets is increased, then rigidity improves, but application expansion is limited due to other property compromises

Engineering Contradiction:

ImproverigidityVSAvoidapplication expansion

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The sheet is divided into multiple layers with different functions: biaxially oriented layers for rigidity and heat resistance, and non-oriented layers for transparency and impact resistance. This segmentation allows each layer to contribute its strengths without compromising overall performance, enabling both increased thickness and broad application suitability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the multilayer sheet have different material properties tailored to specific functional requirements. The biaxially oriented layers provide localized rigidity and heat resistance where needed, while non-oriented layers provide localized transparency and impact resistance, creating a composite structure with optimized overall performance for diverse applications.

Inventive Principle:

Principle #3Local quality

2Strength

If biaxially oriented polypropylene films with different melting points are laminated to increase thickness, then transparency and mechanical properties are maintained, but rigidity is insufficient for further application expansion

Engineering Contradiction:

ImproverigidityVSAvoidapplication expansion

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The invention creates a composite material system combining biaxially oriented polypropylene layers with non-oriented polypropylene layers. This composite structure leverages the rigidity and heat resistance of oriented layers while incorporating the transparency and impact resistance of non-oriented layers, achieving superior overall rigidity that enables expanded applications.

Inventive Principle:

Principle #40Composite materials

3Strength

If a single-layer polypropylene sheet is used, then manufacturing is simple, but rigidity and mechanical properties are insufficient

Engineering Contradiction:

ImproverigidityVSAvoidmultilayer structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The single-layer structure is segmented into multiple functional layers, each contributing specific mechanical properties. The biaxially oriented layers provide rigidity and heat resistance, while non-oriented layers provide transparency and impact resistance. This segmentation increases rigidity despite the added structural complexity.

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If thin polypropylene sheets are used, then manufacturing and handling are easier, but application scope is limited

Engineering Contradiction:

Improveapplication scopeVSAvoidsheet thickness

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The multilayer composite structure enables increased thickness without compromising mechanical properties or handling characteristics. The combination of oriented and non-oriented layers creates a synergistic effect where the overall sheet becomes thicker and more rigid while maintaining ease of manufacturing and handling, thereby expanding application scope.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP4245533B1Multilayered polypropylene sheet

Publication Date: 2025.11.26 FP CORP

Figure 1(A)~1(B)
Figure 2
Figure 3

AI summary

A polypropylene multilayer sheet comprising: a biaxially oriented polypropylene layer F having a melting point TmF; and a biaxially oriented polypropylene layer N having a melting point TmN, the biaxially oriented polypropylene layer N and the biaxially oriented polypropylene layer F being alternately laminated, the polypropylene multilayer sheet having a thickness of 0.30 to 3.0 mm, wherein TmF>TmN, a total number of layers is 3 to 11, the biaxially oriented polypropylene layer F is formed of a resin composition containing: a polypropylene-based resin as a component (A); and an inorganic filler as a component (B), a weight ratio of the component (B)/[the component (A) + the component (B)] is 0.5 to 60 wt%, the biaxially oriented polypropylene layer N is formed of a resin composition containing: a polypropylene-based resin as a component (a); and a component (B) as an optional component, and a weight ratio of the component (B)/[the component (a) + the component (B)] is 0 to 10 wt%.