TPU (Thermoplastic Polyurethane) sealing rings occupy a core position in the industrial sealing field due to their integrated advantages of 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, as specialized products optimized for specific working conditions, precisely meet the sealing requirements of hydraulic systems, transmission machinery, high-temperature equipment, and other scenarios through formula modification and process upgrading. Their performance directly determines equipment operating efficiency and service life. Based on industry-recognized technical standards and practical production experience, this document systematically analyzes the core characteristics, application scenarios, and technical key points of the three types of sealing rings, providing practical references for selection, production, and application in industrial settings.
TPU oil-resistant sealing rings are based on polyether or polyester TPU, modified with oil-resistant additives, featuring excellent resistance to mineral oil, hydraulic oil, fuel oil, and other media erosion. Industry-recognized key indicators include: volume change rate ≤ 5% and tensile strength retention rate ≥ 80% after 72-hour immersion in mineral oil at 40℃; permeability to diesel, gasoline, and other fuels ≤ 0.3g/(cm2·24h), effectively preventing oil leakage and material swelling. Meanwhile, they maintain the high elasticity of TPU substrates, with compression set ≤ 15% (under 70℃×22h conditions), adapting to the reciprocating motion requirements of dynamic sealing scenarios.
Focusing on oil-contacting industrial scenarios, they include hydraulic system sealing (such as hydraulic cylinders, hydraulic valve groups), fuel pipeline sealing (automotive fuel tanks, construction machinery fuel pipelines), industrial gearbox sealing, machine tool hydraulic circuit sealing, etc. Particularly suitable for medium and high-pressure working conditions (pressure ≤ 31.5MPa), they can replace traditional rubber sealing rings to achieve longer service life and reduce equipment maintenance frequency.
In terms of formulation, polyether TPU is used as the base material, with phosphazene-based oil-resistant additives and anti-swelling agents added to optimize compatibility between the substrate and oil; vulcanization process parameters are controlled at 160-180℃ for 10-15 minutes to avoid oil resistance degradation caused by high temperatures; mold precision is controlled within a tolerance of ±0.02mm to ensure sealing surface fit and reduce oil penetration channels; finished products must undergo 72-hour oil immersion testing to eliminate those with excessive volume change rates.
Wear resistance is enhanced through the addition of reinforcing fillers, with core indicators meeting industry standards: Shore hardness A85-95, wear volume loss ≤ 0.1cm3 (per ASTM D2240 wear test standard), friction coefficient ≤ 0.15, capable of withstanding ≥ 5 million cycles in reciprocating motion scenarios without significant wear. Meanwhile, they maintain good elastic recovery with elongation at break ≥ 300%, adapting to vibration and displacement compensation requirements in dynamic sealing.
Mainly used in high-friction, high-frequency motion sealing parts, 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 parts (crusher, conveyor seals), automated equipment linear guide seals, etc. They can maintain stable sealing performance in harsh working conditions with excessive dust and particulate impurities, suitable for construction machinery, mining equipment, automated production lines, and other fields.
Adopting "substrate modification + reinforcing filler compounding" technology, 5%-10% carbon fiber or PTFE micro-powder is added to improve surface wear resistance; molding pressure is controlled at 15-25MPa to ensure uniform dispersion of fillers and avoid uneven local wear resistance; post-processing includes deburring (precision ±0.01mm) and surface polishing to reduce the friction coefficient of the sealing surface; finished products must pass reciprocating friction testing (100 cycles/min, load 5MPa) to verify wear life before leaving the factory.
Through copolymerization modification and crosslinking agent optimization, the temperature resistance limit of traditional TPU is broken. Industry-recognized indicators include: long-term service temperature range of -40℃~120℃, short-term (≤2h) temperature resistance up to 150℃; tensile strength retention rate ≥ 85% and compression set ≤ 20% after 72-hour thermal aging at 120℃. Meanwhile, they possess good low-temperature elasticity, without embrittlement at -40℃, and no attenuation of sealing performance, adapting to alternating high and low-temperature working conditions.
Focusing on sealing requirements in high-temperature environments, they include high-temperature hydraulic systems (such as hot rolling mill hydraulic circuits), engine peripheral sealing (automotive engine valve cover gaskets, exhaust pipe seals), drying equipment sealing (industrial ovens, dryers), auxiliary sealing of steam pipelines, new energy vehicle motor housing seals, etc. They can replace fluororubber sealing rings to reduce costs, achieving equivalent sealing effects in working conditions below 120℃.
Adipate-based TPU substrates are copolymerized and modified with MDI-type crosslinking agents to improve the thermal stability of molecular chains; vulcanization temperature is controlled at 170-190℃, and crosslinking time is extended to 15-20 minutes to ensure sufficient molecular crosslinking; 0.5%-1% antioxidants (such as hindered phenols) are added to inhibit high-temperature aging; finished products must undergo high-low temperature cycle testing (-40℃×4h→120℃×4h, 5 cycles) to verify sealing integrity and dimensional stability.
The industry currently focuses on the R&D of halogen-free flame-retardant and low-VOC emission environmentally friendly TPU materials. By replacing traditional petrochemical raw materials with bio-based monomers, the product carbon footprint is reduced by 15%-20%, adapting to fields with strict environmental requirements such as new energy and electronics.
Integrated modification of oil resistance + wear resistance + high-temperature resistance has become a research hotspot. Through the composite addition of nano-scale fillers (such as graphene, nano-silica), a single sealing ring can meet multiple working condition requirements simultaneously, reducing the number of components in the equipment sealing system.
3D printing, precision injection molding, and other technologies are gradually popularized, enabling customized production of sealing rings with complex cross-sections. Mold tolerance control precision is improved to ±0.01mm, adapting to the high-precision sealing requirements of high-end equipment.
Through targeted formula modification and process optimization, TPU oil-resistant sealing rings, TPU wear-resistant sealing rings, and TPU high-temperature resistant sealing rings have respectively solved 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 conservation, and environmental protection, the three types of products are developing in the direction of multifunctionality, environmental friendliness, and precision, providing more reliable sealing solutions for hydraulic machinery, automotive manufacturing, new energy, and other fields. Their application scenarios will be further expanded with technological upgrading.
