Thermoplastic Elastomer Plug Composition for Medical Container Sealing
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Solution Overview
Problem
Conventional thermoplastic elastomer compositions for medical container plugs lack sufficient resealability and coring resistance, leading to fluid leakage and needlestick resistance issues, especially when a needle is inserted for an extended period or with large fluid volumes.
Innovation Solution
A thermoplastic elastomer composition comprising a hydrogenated block copolymer, polypropylene resin, and polyphenylene ether resin, with specific molecular weight ranges and ratios, combined with a non-aromatic softener, which enhances resealability and coring resistance by improving mechanical strength and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the plug body is increased to improve resealability, then fluid leakage resistance is improved, but needlestick resistance deteriorates due to increased resistance during needle insertion and removal
Solution Approach 1:
The patent changes the chemical composition parameters of the plug body material by using a specific thermoplastic elastomer composition (hydrogenated block copolymer with vinyl aromatic hydrocarbon compound and conjugated diene compound in specific ratios) to achieve optimal balance between resealability and needlestick resistance without changing the physical thickness parameter
Solution Approach 2:
The patent uses a composite material system consisting of hydrogenated block copolymer, vinyl aromatic hydrocarbon compound, and conjugated diene compound in specific weight ratios (70-95 wt% hydrogenated block copolymer, 5-20 wt% vinyl aromatic hydrocarbon compound, 5-20 wt% conjugated diene compound) to achieve both good resealability and acceptable needlestick resistance
2Reliability
If the clamping force is increased by decreasing the internal volume of the outer plug part to improve resealability, then fluid leakage resistance is improved, but coring occurs due to excessive force during needle insertion
Solution Approach 1:
The patent changes the material composition parameters to achieve the desired clamping force through material properties rather than geometric constraints, using hydrogenated block copolymer with specific molecular weight and composition ratios to provide both adequate sealing force and resistance to coring
3Reliability
If rubber materials are used to achieve good resealability, then fluid leakage resistance is improved, but production complexity increases due to multiple processing steps including vulcanization
Solution Approach 1:
The patent extracts the vulcanization step from the production process by using thermoplastic elastomer materials that do not require cross-linking, thereby simplifying the manufacturing process while maintaining good resealability through the specific polymer composition
Solution Approach 2:
The patent adopts a thermoplastic elastomer composition that can be processed through simple injection molding without complex vulcanization equipment, making the production process more economical and suitable for disposable medical containers
Data Source
AI summary
A thermoplastic elastomer composition including:100 parts by mass of a hydrogenated block copolymer (a);from 10 to 50 parts by mass of a polypropylene resin (b);from 5 to 100 parts by mass of a polyphenylene ether resin (c); andfrom 75 to 200 parts by mass of a non-aromatic softener (d), whereinthe hydrogenated block copolymer (a) contains a hydrogenated block copolymer (a-1) obtained by hydrogenation, the hydrogenated block copolymer (a-1) comprising at least one polymer block A1 including mainly a vinyl aromatic hydrocarbon compound monomer unit, and at least one polymer block B1 including mainly a conjugated diene compound monomer unit,a weight-average molecular weight of the hydrogenated block copolymer (a-1) is from 100,000 to 550,000, anda content of all vinyl aromatic hydrocarbon compound monomer units in the hydrogenated block copolymer (a-1) is more than 20% by mass and 50% by mass or less.