Hydrogenated Block Copolymer Resolves Trade-Offs in Polypropylene

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Solution Overview

Problem

Conventional polypropylene resin compositions struggle to achieve a balance between low temperature impact resistance, flexibility, transparency, and low stickiness, with improvements in one property often compromising others, making it difficult to attain high levels of all these properties simultaneously.

Innovation Solution

A hydrogenated block copolymer with specific configurations, including a vinyl aromatic compound unit and a conjugated diene compound unit, is developed, featuring a high degree of hydrogenation, a specific butylene and/or propylene content, and a microphase separated structure, which is incorporated into a polypropylene resin composition to enhance the balance of these properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional polypropylene resin compositions are used to improve low temperature impact resistance, then flexibility is reduced

Engineering Contradiction:

Improvelow temperature impact resistanceVSAvoidflexibility

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent employs a composite material system consisting of polypropylene resin blended with a specific hydrogenated block copolymer. This copolymer contains both polypropylene segments (providing impact resistance) and polyethylene segments (providing flexibility), creating an internal composite structure that simultaneously delivers both required properties without the traditional trade-off

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The hydrogenated block copolymer exhibits local quality differentiation through its block structure: polypropylene blocks provide local regions of high impact resistance while polyethylene blocks provide local regions of flexibility. This spatial differentiation of properties within the material structure allows simultaneous achievement of both characteristics at the macro level

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If polypropylene resin compositions are optimized for transparency, then low stickiness deteriorates

Engineering Contradiction:

ImprovetransparencyVSAvoidstickiness

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The patent utilizes parameter changes in the molecular structure of the hydrogenated block copolymer, specifically controlling the degree of hydrogenation and the block composition ratios. By adjusting these parameters, the material achieves a state where crystalline regions provide transparency while amorphous regions control surface properties to reduce stickiness

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If flexibility is improved in polypropylene resin compositions, then low temperature impact resistance decreases

Engineering Contradiction:

ImproveflexibilityVSAvoidlow temperature impact resistance

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The hydrogenated block copolymer acts as an internal composite where polyethylene blocks contribute flexibility and polypropylene blocks contribute impact resistance. This self-composite structure eliminates the need to choose between flexibility and impact resistance by integrating both functionalities at the molecular level

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 hydrogenated block copolymer effectively imparts a good balance of low temperature impact resistance, flexibility, and low stickiness to molded bodies, overcoming the trade-off relationships seen in conventional techniques.

Implementation Method 1

a microphase separated structure comprises a spherical structure

Methodology Applied

Scientific EffectMicrophase separation:

Implementation Method 2

the hydrogenated block copolymer has a crystallization peak at -20 to 80°C and has a heat of crystallization of 0.1 to 10 J/g

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 3

a tan δ peak (Tg1), which is observed in a temperature-loss tangent (tan δ) curve obtained by the solid viscoelasticity measurement (1 Hz) of the hydrogenated block copolymer and indicates the glass transition of the hydrogenated block copolymer

Methodology Applied

Scientific EffectGlass transition:

Data Source

PatentEP3572444B1Hydrogenated block copolymer, polypropylene resin composition, and molded body

Publication Date: 2023.06.14 ASAHI KASEI KOGYO KABUSHIKI KAISHA

Figure 1~2
Figure 3~4

AI summary

The hydrogenated block copolymer according to the present invention is a hydrogenated block copolymer containing, in the molecule, a polymer block (C) having a conjugated diene compound as a main component, a polymer block (B) having a conjugated diene compound as a main component, and a polymer block (S) having a vinyl aromatic compound as a main component, wherein: the polymer block (B) contains polymer blocks (B1) and (B2); in the hydrogenated block copolymer, a content of the polymer block (C) is 1 to 20 mass%, a content of the polymer block (B) is 73 to 97 mass%, and a content of the polymer block (S) is 1 to 15 mass%; an amount of vinyl bond before hydrogenation of the polymer block (C) is 1 to 25 mol%, an amount of vinyl bond of the polymer block (B1) is 40 to 60 mol%, and an amount of vinyl bond of the polymer block (B2) is 60 to 100 mol%; and a degree of hydrogenation is 80 mol% or more.