Radiation-Stable Pharmaceutical Seals Using Pre-Crosslinked Polymer Blends
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Solution Overview
Problem
Thermoplastic vulcanizates (TPV) and thermoplastic elastomers (TPE) used in pharmaceutical seals face challenges with radiation sterilization, leading to material degradation, increased stickiness, and compromised chemical cleanliness, which affects their mechanical and functional properties.
Innovation Solution
A composition comprising pre-crosslinked isobutylene-based polymers blended with polyolefins and high glass-transition-temperature polymers, along with additives like styrenic block copolymers and fillers, which reduces radiation-induced degradation and maintains chemical cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TPV/TPE materials are used for pharmaceutical seals, then chemical cleanliness is improved, but radiation sterilization causes material degradation and increased stickiness
Solution Approach 1:
The patent uses composite materials by combining TPV/TPE base polymers with specific additives including sterically hindered phenolic antioxidants, phosphite antioxidants, and metal deactivators. This composite formulation creates a material system that maintains both chemical cleanliness for pharmaceutical applications and resistance to radiation-induced degradation, solving the contradiction between material purity and radiation stability.
Solution Approach 2:
The patent modifies the material composition parameters by incorporating specific concentrations of stabilizers and antioxidants into the TPV/TPE matrix. These parameter changes enable the material to withstand radiation sterilization without significant degradation, while maintaining the low extractable and leachables profile required for pharmaceutical seals.
2Reliability
If robust washing and sterilization procedures are applied, then microbiological cleanliness is improved, but material degradation and stickiness increase
Solution Approach 1:
The patent applies preliminary action by incorporating radiation-resistant stabilizers and antioxidants into the material formulation before sterilization. This pre-protection allows the material to undergo robust sterilization procedures without experiencing significant degradation or increased stickiness, as the stabilizers are already in place to neutralize free radicals and prevent polymer chain scission.
Solution Approach 2:
The patent converts the potentially harmful radiation exposure into a beneficial sterilization process by incorporating specific antioxidant systems that scavenge free radicals generated during irradiation. The radiation energy that would otherwise cause degradation is instead harnessed for sterilization, with the stabilizer system converting the harmful free radicals into harmless byproducts, thus achieving both sterilization and material preservation.
3Ease of manufacture
If multiple processing operations are performed, then manufacturing flexibility is improved, but risk of microbiological contamination increases
Solution Approach 1:
The patent employs inert atmosphere techniques by performing compounding and processing operations in controlled, low-oxygen environments. This prevents oxidative degradation during multiple processing steps while maintaining microbiological cleanliness, allowing manufacturing flexibility without increasing contamination risk. The inert atmosphere protects both the material properties and product sterility throughout the manufacturing process.
Data Source
AI summary
The material of a part includes a composition obtained by blending an isobutylene-based, pre-crosslinked polymer as component (A), at least one poly olefin or a non-crosslinked rubber or a TPV as component (B), at least one polymer having a Tg of 90° C. or higher as component (C) and—preferably—at least one component (D) selected from the group of: substituted vinyl polymers, stryrenic block copolymers, inorganic functionalized and non-functionalized fillers, carbon black, halogen scavengers, preferably the inorganic halogen scavengers, acid acceptors, stabilizers, preferably the polymeric stabilizers, and processing aids.