Multilayer Rubber Hose With Nitrosamine-Free Drinking Water Liner
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Solution Overview
Problem
Existing multilayer thermoplastic and rubber hoses, particularly those with NSF/ANSI/CAN 61 certification, face challenges in cold climates due to limited low-temperature performance and stiffness, and often contain nitrosamines that can leach into drinking water, failing to meet safety standards.
Innovation Solution
Development of multilayer thermoplastic and rubber hoses with a thermoplastic UHMWPE inner tube, a blend of natural rubber and styrene-butadiene copolymer, and an ethylene propylene diene monomer rubber cover layer, using sulfur and sulfonamide accelerators to avoid nitrosamine formation, along with a reinforcing layer made from sustainable materials, ensuring flexibility, durability, and compliance with NSF/ANSI/CAN 61 standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extruded PVC products are used for NSF/ANSI/CAN 61 certification, then certification compliance is achieved, but low temperature performance and flexibility deteriorate
Solution Approach 1:
The patent uses a composite material structure with multiple layers: an inner tube made of NSF/ANSI/CAN 61 certified thermoplastic material for compliance, an intermediate layer of uncured rubber compound for flexibility, and an outer cured rubber cover for durability. This multi-layer composite approach allows each layer to contribute its specific properties, resolving the contradiction between certification compliance and flexibility.
Solution Approach 2:
Different layers of the hose are assigned different material properties tailored to specific functional requirements. The inner tube uses rigid certified thermoplastic for safety compliance, while the outer cover uses flexible cured rubber for operational ease. This local differentiation of material qualities allows the hose as a whole to satisfy both certification and flexibility requirements.
2Ease of manufacture
If extruded PVC products are used, then manufacturing simplicity is maintained, but low temperature performance deteriorates
Solution Approach 1:
The patent employs a composite construction where the inner tube uses extruded thermoplastic for manufacturing simplicity, while the outer cured rubber layers provide enhanced low-temperature performance. The intermediate uncured rubber layer acts as a transition zone, combining the processing advantages of thermoplastics with the low-temperature flexibility of cured rubbers.
3Ease of manufacture
If conventional rubber compounds with nitrosamine-generating accelerators are used, then manufacturing ease is maintained, but safety compliance deteriorates
Solution Approach 1:
The patent removes nitrosamine-generating accelerators from the rubber compound formulation. By extracting this harmful component and replacing it with alternative curing systems, the patent maintains the ease of rubber processing while eliminating the nitrosamine leaching issue, thus achieving both manufacturing ease and safety compliance.
Solution Approach 2:
The patent converts the potential harm of nitrosamine generation into a benefit by deliberately selecting accelerator systems that do not produce nitrosamines. This choice, while potentially complicating the formulation slightly, ultimately simplifies the product by eliminating safety concerns and certification barriers, making the hose suitable for drinking water applications.
Data Source
AI summary
A hose including an inner tube, a reinforcement layer disposed outwardly from the inner tube, and a cover layer disposed outwardly from the reinforcement layer, in which the hose meets requirements of NSF/ANSI/CAN 61 standard, and in some aspects, at least the inner tube is devoid of nitrosamines. In some cases, the inner tube includes ultra-high molecular weight polyethylene. In some other aspects, the inner tube includes other thermoplastic material. In some cases, the cover layer is based on a rubber material. Also, the hose may contain water within a lumen defined inside the inner walls of the inner tube.