Thermoplastic Elastomer Stopper Composition for Medical Containers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Medical container stoppers made from thermoplastic elastomers face challenges in achieving satisfactory liquid leakage resistance and needlestick resistance, particularly when a needle is inserted for an extended period, leading to issues with resealability and needle retention.
Innovation Solution
A thermoplastic elastomer composition comprising specific proportions of hydrogenated block copolymers, polypropylene-based resin, polyphenylene ether resin, and non-aromatic softeners, which provides improved needlestick resistance and liquid leakage resistance by optimizing the molecular weight and vinyl aromatic hydrocarbon content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the stopper is increased to improve liquid leakage resistance, then liquid leakage resistance is improved, but needlestick resistance increases making injection difficult
Solution Approach 1:
The invention changes the chemical composition parameters of the stopper material by incorporating specific ratios of hydrogenated block copolymer (5-50 mass%), polypropylene-based resin (30-65 mass%), and polyphenylene ether resin (5-20 mass%). This compositional parameter change allows achieving both high liquid leakage resistance and low needlestick resistance without increasing stopper thickness
Solution Approach 2:
The invention uses a composite material system combining three different polymer resins with complementary properties. The hydrogenated block copolymer provides elasticity and resealability, polypropylene-based resin provides structural integrity and needle penetration properties, and polyphenylene ether resin enhances chemical resistance and dimensional stability. This composite approach resolves the contradiction between liquid leakage resistance and needlestick resistance
2Ease of operation
If the softness of the stopper is increased to reduce needlestick resistance, then needlestick resistance is reduced, but needle retention properties decrease causing needle to fall out
Solution Approach 1:
The invention optimizes the softness parameter through controlled composition rather than extreme softening. The hydrogenated block copolymer content (5-50 mass%) and polypropylene-based resin content (30-65 mass%) are balanced to achieve moderate softness that allows needle penetration while the polyphenylene ether resin (5-20 mass%) provides structural support for needle retention, resolving the contradiction between ease of insertion and needle holding
3Reliability
If conventional rubber materials are used to achieve resealability and liquid leakage resistance, then liquid leakage resistance is improved, but production complexity and cost increase due to multiple processing steps
Solution Approach 1:
The invention adopts a disposable stopper design made from thermoplastic elastomer composition that can be molded in a single step without requiring vulcanization or complex processing. This eliminates the need for large-scale vulcanization equipment and multiple processing steps, significantly reducing production complexity and cost while maintaining liquid leakage resistance through optimized material composition
Solution Approach 2:
The invention changes the material state from vulcanized rubber to thermoplastic elastomer, which allows processing at lower temperatures without vulcanization. The specific composition parameters (hydrogenated block copolymer 5-50 mass%, polypropylene-based resin 30-65 mass%, polyphenylene ether resin 5-20 mass%) enable the material to achieve rubber-like elasticity and sealing properties through composition alone, eliminating complex processing steps
Data Source
AI summary
This thermoplastic elastomer composition comprises: 100 parts by mass of a hydrogenated block copolymer (a); from 3 to 50 parts by mass of a polypropylene-based resin (b), from 5 to 100 parts by mass of a polyphenylene ether resin (c), and from 50 to 200 parts by mass of a non-aromatic softener (d), the hydrogenated block copolymer (a) is able to be formed by hydrogenating a block copolymer that comprises at least one polymer block A comprising a vinyl aromatic hydrocarbon compound monomer unit as a primary component and at least one polymer block B comprising a conjugated diene compound monomer unit as a primary component, and a weight average molecular weight of the hydrogenated block copolymer (a) is from 100,000 to 350,000.