Polypropylene Resin Composition with Hydrogenated Block Copolymers
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Solution Overview
Problem
Polypropylene-based resin compositions used in medical and packaging applications lack a favorable balance of heat sealability, flexibility, transparency, shock resistance, and low stickiness, limiting their effectiveness in producing sheet-shaped molded bodies for medical use, foodstuff packaging, and clothing.
Innovation Solution
A resin composition comprising a polypropylene-based resin, two specific hydrogenated block copolymers with defined aromatic vinyl and conjugated diene compound units, and a polyolefin resin, optimized in terms of molecular weight, vinyl content, and mass ratios to achieve improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polypropylene-based resin is used, then chemical resistance and mechanical properties are improved, but heat sealability, flexibility, transparency, and shock resistance deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of polypropylene-based resin combined with two specific hydrogenated block copolymers (one with 40-60 mol% vinyl content and another with 60-80 mol% vinyl content). This composite approach allows the polypropylene to provide mechanical strength and chemical resistance while the hydrogenated block copolymers contribute heat sealability, flexibility, and shock resistance, thereby resolving the contradiction between mechanical properties and heat sealability.
Solution Approach 2:
The patent changes the chemical composition parameters by introducing hydrogenated block copolymers with specific vinyl content ranges (40-60 mol% and 60-80 mol%). By controlling the vinyl content and hydrogenation degree, the patent optimizes the balance between rigidity (from polypropylene) and flexibility/heat sealability (from hydrogenated block copolymers), thus resolving the contradiction while maintaining both mechanical strength and heat sealability.
2Ease of operation
If elastomer is added to polypropylene-based resin, then flexibility and shock resistance are improved, but transparency and surface smoothness deteriorate
Solution Approach 1:
The patent uses hydrogenated block copolymers with controlled vinyl content (40-80 mol%) and degree of hydrogenation (80-95%). By precisely controlling these parameters, the patent achieves a balance where the elastomeric properties (flexibility and shock resistance) are sufficient for medical applications while maintaining high transparency and surface smoothness, unlike conventional elastomer additions.
Solution Approach 2:
The patent introduces specific functional components (hydrogenated block copolymers with defined vinyl content ranges) into the polypropylene matrix. These components are distributed at controlled concentrations (5-50 parts per 100 parts polypropylene) to provide localized flexibility and shock resistance while the bulk material maintains transparency and surface quality, resolving the contradiction between flexibility and transparency.
3Reliability
If hydrogenated block copolymer with high vinyl content is added, then heat sealability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the elastomeric function into two distinct hydrogenated block copolymers with different vinyl content ranges (40-60 mol% and 60-80 mol%). This segmentation allows each component to contribute differently to the overall performance: one provides baseline flexibility and heat sealability, while the other enhances these properties. The divided approach simplifies manufacturing by using standard copolymerization techniques for each component rather than requiring complex single-step synthesis.
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 composition provides a sheet-shaped molded body with enhanced heat sealability, flexibility, transparency, shock resistance, and low stickiness, making it suitable for medical, foodstuff, and clothing packaging applications.
Implementation Method 1
a hydrogenated block copolymer (b), and a hydrogenated block copolymer (c), wherein the hydrogenated block copolymer (b) comprises: at least one polymer block A comprising an aromatic vinyl compound unit as a main constituent; and at least one polymer block B comprising a conjugated diene compound unit as a main constituent, a total content of the aromatic vinyl compound unit in the hydrogenated block copolymer (b) is 5 to 30% by mass, 80 mol% or more of all the conjugated diene compound units in the hydrogenated block copolymer (b) is hydrogenated
Data Source
AI summary
A resin composition according to the present invention contains a polypropylene-based resin (a), a hydrogenated block copolymer (b), and a hydrogenated block copolymer (c) in a particular mass ratio, and the hydrogenated block copolymer (b) and the hydrogenated block copolymer (c) have particular constitution. Moreover, a sheet-shaped molded body according to the present invention contains the resin composition according to the present invention. Furthermore, a packaging material for medical use, foodstuffs or clothes according to the present invention contains the sheet-shaped molded body according to the present invention.