Multilayer Polyolefin Tube for Low-Leaching High-Temperature Purity
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Solution Overview
Problem
The existing pipes made of fluororesin, such as PVDF, while meeting stringent water quality standards for semiconductor cleaning solutions, are disadvantageous in terms of workability and cost, and polyolefin-based resin pipes face issues with calcium and organic substance elution due to catalyst residue, leading to unsatisfactory mechanical strength and oxidative deterioration at elevated temperatures.
Innovation Solution
A multilayer tube structure is developed with a polyolefin-based resin inner layer and a second polyolefin-based resin outer layer, where the inner layer's thickness is optimized to minimize calcium and organic substance elution, and the molecular weight distribution is controlled to enhance mechanical strength, with an optional gas barrier layer for improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fluororesin pipes (PVDF) are used to meet stringent water quality standards, then purity of semiconductor cleaning solution is improved, but workability and cost deteriorate
Solution Approach 1:
The patent uses a composite structure consisting of an inner fluororesin layer (for purity) and an outer polyolefin-based resin layer (for workability and cost reduction). This multi-layer composite pipe combines the advantages of both materials while mitigating their individual disadvantages, allowing the pipe to meet stringent purity standards while improving ease of manufacture and reducing cost.
2Ease of manufacture
If polyolefin-based resin pipes are used to improve workability and cost, then ease of manufacture is improved, but calcium and organic substance elution increases leading to deteriorated mechanical strength
Solution Approach 1:
The patent segments the pipe into two distinct functional layers: an inner layer made of fluororesin that contacts the semiconductor cleaning solution to prevent elution of calcium and organic substances, and an outer layer made of polyolefin-based resin that provides improved workability and cost benefits. This segmentation allows each layer to perform its specific function optimally without compromising the other.
3Ease of manufacture
If polyolefin-based resin is used to reduce cost, then cost is reduced, but oxidative deterioration at elevated temperatures occurs leading to worsened durability
Solution Approach 1:
The patent employs a composite pipe structure where the inner fluororesin layer provides resistance to oxidative deterioration at elevated temperatures, while the outer polyolefin-based resin layer provides cost benefits. The fluororesin layer acts as a protective barrier that prevents direct contact between the aggressive cleaning solution and the more cost-effective polyolefin material, thereby extending the service life of the pipe system.
Data Source
AI summary
A multilayer tube is provided which suppresses the amount of calcium and organic component leaching to a low level and which can be realized as a tube that has mechanical properties at 60° C. This multilayer tube includes a first polyolefin resin layer configuring the innermost layer, and a second polyolefin resin layer arranged outside of the first polyolefin resin layer; the amount of calcium leaching, measured in accordance with SEMI F-57, of the material of the first polyolefin resin layer is less than 30 μg/m2; the ratio of the thickness of the first polyolefin resin layer to the total thickness of the first polyolefin resin layer and the second polyolefin resin layer is 0.011-0.17. By means of this configuration, it is possible to suppress the amount of leaching of calcium and organic substances to a low level, and to realize a pipe having a strength that takes into account a 60° C. use environment.