TPU (Thermoplastic Polyurethane Elastomer) sealing rings hold a core position in the industrial sealing field due to their high elasticity, mechanical stability, and processing adaptability. Among them, TPU oil-resistant sealing rings, TPU wear-resistant sealing rings, and TPU high-temperature resistant sealing rings are sub-products optimized for specific working conditions. Through formula modification and process upgrades, they precisely match the sealing needs of hydraulic systems, transmission machinery, high-temperature equipment, and other scenarios. Their performance directly determines the operating efficiency and service life of equipment. This article, based on industry-recognized technical standards and practical production application experience, systematically analyzes the core characteristics, application scenarios, and technical points of these three types of sealing rings, providing practical reference for selection, production, and application in industrial production.
I. TPU Oil-Resistant Sealing Rings
1. Core Characteristics
TPU oil-resistant sealing rings use polyether-type or polyester-type TPU as the base material and are modified with oil-resistant additives, possessing excellent resistance to mineral oil, hydraulic oil, fuel oil, and other media. Key industry-recognized indicators are: after immersion in mineral oil at 40℃ for 72 hours, the volume change rate is ≤5%, and the tensile strength retention rate is ≥80%; the penetration rate of diesel, gasoline, and other fuels is ≤0.3g/(cm²・24h), effectively preventing oil leakage and material swelling. Simultaneously, it maintains the high elasticity of the TPU substrate, with a compression set of ≤15% (70℃×22h conditions), adapting to the reciprocating motion requirements of dynamic sealing scenarios.
2. Application Scenarios
Focusing on industrial scenarios involving oil contact, including hydraulic system seals (such as hydraulic cylinders and hydraulic valve groups), fuel line seals (automotive fuel tanks, construction machinery fuel lines), industrial gearbox seals, and machine tool hydraulic circuit seals. It is particularly suitable for medium- and high-pressure conditions (pressure ≤31.5MPa), and can replace traditional rubber seals to achieve a longer service life and reduce equipment maintenance frequency.
3. Key Points of Production Process
At the formulation level, polyether-type TPU is used as the base material, with the addition of phosphazene oil-resistant additives and anti-swelling agents to optimize the compatibility between the base material and oil. The vulcanization process is controlled at a temperature of 160-180℃ and a time of 10-15 minutes to avoid the degradation of oil resistance due to high temperatures. Mold precision is controlled within a tolerance of ±0.02mm to ensure the sealing surface fit and reduce oil penetration channels. Finished products must undergo a 72-hour oil immersion test, and products with excessive volume change rate are discarded.
II. TPU Wear-Resistant Sealing Ring
1. Core Characteristics
By adding reinforcing fillers, wear resistance is upgraded. Key indicators meet industry standards: Shore hardness A85-95, wear volume loss ≤0.1cm³ (ASTM D2240 wear resistance test standard), coefficient of friction ≤0.15, and can withstand ≥5 million cycles in reciprocating motion scenarios without significant wear. It maintains excellent elastic recovery with an elongation at break ≥300%, adapting to the vibration and displacement compensation requirements of dynamic sealing.
2. Application Scenarios
Primarily used in sealing components with high friction and high-frequency motion, including transmission machinery sealing surfaces (such as motor shaft seals, reducer output shafts), slider seals (injection molding machine guide pillars, hydraulic cylinder pistons), mining machinery sealing components (crushers, conveyor seals), and linear guide seals in automated equipment. It maintains stable sealing performance even under harsh working conditions with high levels of dust and particulate impurities, making it suitable for engineering machinery, mining equipment, automated production lines, and other fields.
3. Key Points of Production Process
The process employs a "substrate modification + reinforcing filler composite" technology, adding 5%-10% carbon fiber or PTFE micro-powder to improve surface wear resistance; molding pressure is controlled at 15-25MPa to ensure uniform filler dispersion and avoid uneven local wear resistance; post-processing includes deflashing (accuracy ±0.01mm) and surface polishing to reduce the friction coefficient of the sealing surface; finished products must pass a reciprocating friction test (100 times/min, load 5MPa) to verify that the wear life meets the standard before leaving the factory.
III. TPU High Temperature Resistant Sealing Ring
1. Core Characteristics
Through copolymer modification and crosslinking agent optimization, the temperature resistance limitations of traditional TPU are overcome. Industry-recognized indicators are: long-term operating temperature range -40℃~120℃, short-term (≤2h) temperature resistance up to 150℃; after 72h of heat aging at 120℃, tensile strength retention ≥85%, compression set ≤20%. It also possesses excellent low-temperature elasticity, exhibiting no brittleness at -40℃ and maintaining consistent sealing performance, making it suitable for alternating high and low temperature operating conditions.
2. Application Scenarios
Focusing on sealing needs in high-temperature environments, including high-temperature hydraulic systems (such as hot rolling mill hydraulic circuits), engine peripheral seals (automotive engine valve cover, exhaust pipe seals), drying equipment seals (industrial ovens, dryers), steam pipeline auxiliary seals, and new energy vehicle motor housing seals, etc. It can replace fluororubber seals, reducing costs, and achieves equivalent sealing performance in operating conditions below 120℃.
3. Key Manufacturing Process Points
Adipate-ester-based TPU substrate is copolymerized with MDI-type crosslinking agent to improve molecular chain thermal stability; the vulcanization temperature is controlled at 170-190℃, and the crosslinking time is extended to 15-20 minutes to ensure full molecular crosslinking; 0.5%-1% antioxidant (such as hindered phenols) is added to inhibit high-temperature aging; the finished product must undergo high and low temperature cycling tests (-40℃×4h→120℃×4h, 5 cycles) to verify sealing integrity and dimensional stability.
TPU oil-resistant sealing rings, TPU wear-resistant sealing rings, and TPU high-temperature sealing rings, through targeted formula modification and process optimization, respectively solve the three core sealing problems of oil erosion, friction and wear, and high-temperature aging. Against the backdrop of industrial production transforming towards high efficiency, energy saving, and environmental protection, these three types of products are developing towards multi-functionality, environmental friendliness, and precision, providing more reliable sealing solutions for hydraulic machinery, automotive manufacturing, new energy, and other fields. Their application scenarios will further expand with technological upgrades.
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