A polyurethane seal and a method of making the same

Abstract

The application specifically relates to a polyurethane seal and a preparation method thereof, and the polyurethane seal comprises the following raw materials in parts by weight: 40-70 parts of polyurethane prepolymer, 5-20 parts of a chain extender, 10-30 parts of a filler, 4-8 parts of aromatic polyamide fibers, 4-8 parts of maleic anhydride grafted POE, 3-6 parts of a silane coupling agent, 2-5 parts of butyronitrile rubber and 1-5 parts of an auxiliary. The polyurethane seal has good wear resistance, oil resistance, mechanical properties and low compression permanent deformation by adding the aromatic polyamide fibers, the maleic anhydride grafted POE, the silane coupling agent, the filler and the butyronitrile rubber into the polyurethane prepolymer system and using the chain extender to chain-extend the polyurethane prepolymer. The preparation method of the polyurethane seal is high in production efficiency, convenient in operation control, stable in process and beneficial to industrialized production.

Description

Technical Field

[0001] This invention relates to the field of sealing technology, specifically to a polyurethane sealing component and its preparation method. Background Technology

[0002] Currently, sealing components are frequently used in the automotive, aerospace, petrochemical, chemical fiber textile, machinery, metallurgical, and mining industries. In existing technologies, seals made of polyurethane materials are widely used. Polyurethane elastomers are typically produced through polymerization reactions of raw materials such as polyols, isocyanates, and additives, and possess advantages such as excellent mechanical strength, elasticity, and oil resistance. However, with continuous technological advancements and increasingly demanding operating conditions, the operating speed, system temperature, and working pressure of equipment using seals, such as hydraulic cylinders, are also increasing, placing higher demands on the overall performance of seals. However, existing polyurethane seals often suffer from poor wear resistance, mechanical properties, and compression set, making them unsuitable for demanding applications in the automotive, aerospace, and petrochemical industries. Therefore, providing a polyurethane seal with superior wear resistance, oil resistance, and mechanical properties to extend its service life and improve equipment reliability is of significant practical importance. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of the prior art by providing a polyurethane seal and its preparation method. The polyurethane seal has good wear resistance, oil resistance, mechanical properties, and low compression set, effectively reducing friction loss and wear in sealing applications. It has a wide range of applications and good durability. The preparation method of the polyurethane seal has high production efficiency, convenient operation and control, stable process, and is conducive to industrial production.

[0004] The objective of this invention is achieved through the following technical solution: a polyurethane sealing component, comprising the following raw materials in parts by weight: 40-70 parts of polyurethane prepolymer, 5-20 parts of chain extender, 10-30 parts of filler, 4-8 parts of aromatic polyamide fiber, 4-8 parts of maleic anhydride-grafted POE, 3-6 parts of silane coupling agent, 2-5 parts of nitrile rubber, and 1-5 parts of additives; the preparation method of the polyurethane prepolymer comprises the following steps: reacting polyether polyol, polyester polyol and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to hydroxyl groups in the polyether polyol and polyester polyol is 2.1-2.3, to obtain the polyurethane prepolymer.

[0005] Furthermore, the isocyanate includes at least one of toluene diisocyanate and diphenylmethane diisocyanate. Preferably, the isocyanate is composed of toluene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 7-8:2-3.

[0006] Furthermore, the polyether polyol is at least one of polytetrahydrofuran ether diol and polypropylene oxide diol, and the polyester polyol is at least one of polybutylene adipate diol and polycarbonate diol.

[0007] Furthermore, the weight ratio of the polytetrahydrofuran ether diol and the polybutylene adipate diol is 3-4:1-2:1-2.

[0008] Furthermore, the molecular weight of the polytetrahydrofuran ether diol is 1000-2000, the molecular weight of the polypropylene oxide diol is 800-2500, and the molecular weight of the polybutylene adipate diol is 1000-1500.

[0009] Further, the chain extender comprises at least one selected from 1,4-butanediol and 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA). Preferably, the chain extender is composed of 1,4-butanediol and 3,3'-dichloro-4,4'-diaminodiphenylmethane in a weight ratio of 4-6:1-2.

[0010] Furthermore, the filler is at least one of nano-calcium carbonate, carbon black, and nano-silica. Furthermore, each part of the filler comprises the following parts by weight of raw materials: 8-12 parts nano-calcium carbonate, 4-7 parts carbon black, and 3-6 parts nano-silica. This invention achieves interface strengthening by compounding nano-calcium carbonate, carbon black, and nano-silica, and combining them with a silane coupling agent, which helps to improve the wear resistance, oil resistance, and mechanical properties of polyurethane sealants.

[0011] Furthermore, the silane coupling agent is at least one selected from γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and bis-[γ-(triethoxysilane)propyl]tetrasulfide.

[0012] Furthermore, each part of the additive comprises the following raw materials in parts by weight: 0.5-2 parts of lubricant, 0.5-1.5 parts of antioxidant, and 0.5-1.5 parts of light stabilizer.

[0013] Furthermore, the lubricant is at least one of zinc stearate, calcium stearate, and ethylene bis-stearamide.

[0014] Furthermore, the antioxidant is a hindered phenolic antioxidant and a phosphite, wherein the hindered phenolic antioxidant is selected from at least one of antioxidant 1010, antioxidant 1076, antioxidant BHT, and antioxidant 1098. The phosphite is selected from at least one of antioxidant 168 and antioxidant 626.

[0015] Furthermore, the light stabilizer is a benzotriazole light stabilizer. The light stabilizer is at least one selected from 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol, 2'-hydroxy-5'-tert-octylphenylbenzotriazole, 2-(2H-benzotriazole-2-yl)-4-methylphenol, and 2'-hydroxy-5'-tert-octylphenylbenzotriazole.

[0016] The polyurethane seal of this invention is made by compounding aromatic polyamide fibers, maleic anhydride-grafted POE, silane coupling agents, fillers, nitrile rubber, and other raw materials with a polyurethane prepolymer, and using a chain extender to extend the chain of the polyurethane prepolymer. The raw materials achieve good synergy and complementarity, resulting in a polyurethane seal with excellent wear resistance, oil resistance, mechanical properties, and low compression set. It effectively reduces friction loss and wear in reciprocating or rotating sealing applications, and is suitable for sealing applications in humid and oil-sealed environments. It has a wide range of applications and a long service life.

[0017] The present invention also provides a method for preparing the polyurethane seal described above, comprising the following steps:

[0018] (1) Take the raw materials that make up the polyurethane prepolymer in proportion, carry out the prepolymerization reaction, and obtain the polyurethane prepolymer.

[0019] (2) The polyurethane prepolymer, chain extender, maleic anhydride grafted POE, aromatic polyamide fiber, filler, silane coupling agent, nitrile rubber and additives are placed in a disperser in proportion and mixed and reacted at a temperature of 65-75℃ to obtain material A.

[0020] (3) Inject material A into the mold, then put the mold with material A in the curing oven for curing reaction. After material A is completely cured, take it out of the mold to obtain the initial product of the seal.

[0021] (4) The initial seal material after demolding is machined to obtain the required size and shape;

[0022] (5) The initial seal product after turning is post-processed. The post-processing steps include deburring, grinding and cleaning to obtain polyurethane seal.

[0023] Furthermore, in step (1), polyether polyol, polyester polyol and isocyanate are reacted under a nitrogen atmosphere at 85-90℃ for 2.5-3.5 hours, and then vacuum degassing is performed until no bubbles escape to obtain polyurethane prepolymer. The polyether polyol and polyester polyol have been pre-treated by heating and dehydration.

[0024] Furthermore, in step (2), the polyurethane prepolymer, chain extender, maleic anhydride grafted POE, aromatic polyamide fiber, filler, silane coupling agent, nitrile rubber, and additives are placed in a high-speed disperser and mixed at 65-75°C for 8-15 minutes at a speed of 1400-1800 rpm to obtain material A.

[0025] Furthermore, in step (2), the aromatic polyamide fiber is pretreated with plasma at a power of 100-200W for 20-30 minutes. Through this treatment, active groups are generated on the surface of the aromatic polyamide fiber, forming covalent bonds with the silane coupling agent during the mixing reaction, which helps to improve the wettability and adhesion between the aromatic polyamide fiber and the matrix.

[0026] Furthermore, in step (3), the mold is heated to 90-105°C, material A is injected, and cured for 40-80 minutes under a pressure of 6-10 MPa and a temperature of 105-115°C. Then the temperature is raised to 120-130°C and the pressure is reduced to 2-3 MPa for 60-120 minutes.

[0027] This invention employs the selection and dosage adjustment of raw materials for polyurethane seals, and controls the process parameters of each step in the preparation method of polyurethane seals. Specifically, a gradient curing process is used for the polyurethane prepolymer system, which first undergoes high-pressure treatment and then depressurization and heating treatment. This reduces internal defects in the seals and helps promote the orderly arrangement of molecular chains, thereby improving oil resistance and mechanical properties.

[0028] The beneficial effects of this invention are as follows: The polyurethane seal of this invention incorporates aromatic polyamide fibers, maleic anhydride-grafted POE, silane coupling agents, fillers, nitrile rubber, and other raw materials into a polyurethane prepolymer system, and uses a chain extender to extend the chain of the polyurethane prepolymer. The various raw materials work synergistically to produce polyurethane seals with excellent wear resistance, oil resistance, mechanical properties, and low compression set. This effectively reduces friction loss and wear in reciprocating or rotary sealing applications, resulting in a wide range of applications and good durability. The preparation method of the polyurethane seal is highly efficient, easy to operate and control, and has a stable process, facilitating industrial production. Detailed Implementation

[0029] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0030] In some embodiments of the present invention, a polyurethane sealant comprises the following raw materials in parts by weight: 40-70 parts of polyurethane prepolymer, 5-20 parts of chain extender, 10-30 parts of filler, 4-8 parts of aromatic polyamide fiber, 4-8 parts of maleic anhydride-grafted POE, 3-6 parts of silane coupling agent, 2-5 parts of nitrile rubber, and 1-5 parts of additives; the preparation method of the polyurethane prepolymer comprises the following steps: reacting polyether polyol, polyester polyol and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to hydroxyl groups in the polyether polyol and polyester polyol is 2.1-2.3, to obtain the polyurethane prepolymer.

[0031] In some embodiments of the present invention, a polyurethane sealant comprises the following raw materials in parts by weight: 55-65 parts of polyurethane prepolymer, 12-18 parts of chain extender, 15-20 parts of filler, 4-8 parts of aromatic polyamide fiber, 4-8 parts of maleic anhydride-grafted POE, 3-6 parts of silane coupling agent, and 1-5 parts of additives; the preparation method of the polyurethane prepolymer comprises the following steps: reacting polyether polyol, polyester polyol and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to hydroxyl groups in the polyether polyol and polyester polyol is 2.1-2.3, to obtain the polyurethane prepolymer.

[0032] In some embodiments of the present invention, the isocyanate includes at least one of toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). Preferably, the isocyanate is composed of toluene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 7-8:2-3.

[0033] In some embodiments of the present invention, the polyether polyol is at least one of polytetrahydrofuran ether diol and polypropylene oxide diol, and the polyester polyol is at least one of polybutylene adipate diol and polycarbonate diol.

[0034] In some embodiments of the present invention, the polyether polyol is composed of polytetrahydrofuran ether diol and polypropylene oxide diol in a weight ratio of 2-3:1, and the weight ratio of the polyether polyol to the polyester polyol is 3-4:1-2.

[0035] In some embodiments of the present invention, the molecular weight of the polytetrahydrofuran ether diol is 1000-2000, the molecular weight of the polypropylene oxide diol is 800-2500, and the molecular weight of the polybutylene adipate diol is 1000-1500.

[0036] In some embodiments of the present invention, the chain extender comprises at least one selected from 1,4-butanediol and 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA). Preferably, the chain extender is composed of 1,4-butanediol and 3,3'-dichloro-4,4'-diaminodiphenylmethane in a weight ratio of 4-6:1-2.

[0037] In some embodiments of the present invention, the filler is at least one of nano-calcium carbonate, carbon black, and nano-silica. Further, each part of the filler comprises the following parts by weight of raw materials: 8-12 parts nano-calcium carbonate, 4-7 parts carbon black, and 3-6 parts nano-silica. The present invention achieves interface strengthening by compounding nano-calcium carbonate, carbon black, and nano-silica, and combining them with a silane coupling agent, which helps to improve the wear resistance, oil resistance, and mechanical properties of polyurethane sealants.

[0038] In some embodiments of the present invention, the silane coupling agent is at least one selected from γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and bis-[γ-(triethoxysilyl)propyl]tetrasulfide.

[0039] Furthermore, each part of the additive comprises the following raw materials in parts by weight: 0.5-2 parts of lubricant, 0.5-1.5 parts of antioxidant, and 0.5-1.5 parts of light stabilizer.

[0040] In some embodiments of the present invention, the lubricant is at least one of zinc stearate, calcium stearate, and ethylene bis-stearamide.

[0041] In some embodiments of the present invention, the antioxidant is a hindered phenolic antioxidant and a phosphite; the hindered phenolic antioxidant is selected from at least one of antioxidant 1010, antioxidant 1076, antioxidant BHT and antioxidant 1098; the phosphite is selected from at least one of antioxidant 168 and antioxidant 626.

[0042] In some embodiments of the present invention, the light stabilizer is a benzotriazole light stabilizer. The light stabilizer is at least one selected from 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol, 2'-hydroxy-5'-tert-octylphenylbenzotriazole, 2-(2H-benzotriazole-2-yl)-4-methylphenol, and 2'-hydroxy-5'-tert-octylphenylbenzotriazole.

[0043] The present invention also provides a method for preparing a polyurethane seal, comprising the following steps:

[0044] (1) Take the raw materials that make up the polyurethane prepolymer in proportion, carry out the prepolymerization reaction, and obtain the polyurethane prepolymer.

[0045] (2) According to the proportion, the polyurethane prepolymer, chain extender, maleic anhydride grafted POE, aromatic polyamide fiber, filler, silane coupling agent, nitrile rubber and additives are placed in a high-speed disperser and mixed at 65-75℃ for 8-15 minutes at a speed of 1400-1800 rpm to obtain material A.

[0046] (3) Inject material A into the mold, then put the mold with material A in the curing oven for curing reaction. After material A is completely cured, take it out of the mold to obtain the initial product of the seal.

[0047] (4) The initial seal material after demolding is machined to obtain the required size and shape;

[0048] (5) The initial seal product after turning is post-processed. The post-processing steps include deburring, grinding and cleaning to obtain polyurethane seal.

[0049] In some embodiments of the present invention, in step (1), polyether polyol, polyester polyol and isocyanate are reacted under a nitrogen atmosphere at 85-90°C for 2.5-3.5 hours, and then vacuum degassing is performed until no bubbles escape to obtain polyurethane prepolymer. The polyether polyol and polyester polyol are pre-treated by heating and dehydration.

[0050] In some embodiments of the present invention, the aromatic polyamide fiber is pretreated with plasma before use, with a treatment power of 100-200W and a treatment time of 20-30 minutes. The aromatic polyamide fiber is poly(m-phenylene isophthalamide) fiber (aramid 1313).

[0051] In some embodiments of the present invention, in step (3), the mold is heated to 90-105°C, material A is injected, and cured for 40-80 min under pressure of 6-10 MPa and temperature of 105-115°C. Then the temperature is raised to 120-130°C and the pressure is reduced to 2-3 MPa for 60-120 min.

[0052] Example 1

[0053] In this embodiment, a polyurethane sealant comprises the following raw materials in parts by weight: 60 parts of polyurethane prepolymer, 15 parts of chain extender, 20 parts of filler, 6 parts of aromatic polyamide fiber, 6 parts of maleic anhydride-grafted POE, 4 parts of silane coupling agent, 3 parts of nitrile rubber, and 2.8 parts of additives; the preparation method of the polyurethane prepolymer includes the following steps: reacting polyether polyol, polyester polyol and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to hydroxyl groups in the polyether polyol and polyester polyol is 2.1, to obtain the polyurethane prepolymer.

[0054] Furthermore, the aromatic polyamide fiber is poly(m-phenylene isophthalamide) fiber, which is pre-treated with plasma at a power of 200W for 25 minutes. The poly(m-phenylene isophthalamide) fiber is made from Tymeda meta-aramid natural white short fiber. The maleic anhydride-grafted POE is Dow AMPLIFY GR209 maleic anhydride-grafted POE. The nitrile rubber is Reynolds nitrile rubber DN3350.

[0055] Furthermore, the isocyanate is composed of toluene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 4:1.

[0056] Furthermore, the polyether polyol is composed of polytetrahydrofuran ether diol and polypropylene oxide diol in a weight ratio of 2.5:1, and the polyester polyol is polybutylene adipate diol. The weight ratio of the polyether polyol to polybutylene adipate diol is 3.5:1.5. The polytetrahydrofuran ether diol is PTMG1000 from Jiangsu Haolong Chemical Co., Ltd., the polypropylene oxide diol is PPG2000 from Jiangsu Maoheng Chemical Co., Ltd., and the polybutylene adipate diol is PBA1000 from Jiangsu Haolong Chemical Co., Ltd.

[0057] Furthermore, the chain extender is composed of 1,4-butanediol and 3,3'-dichloro-4,4'-diaminodiphenylmethane in a weight ratio of 5:1.5.

[0058] Furthermore, each portion of the filler comprises the following raw materials in parts by weight: 10 parts nano-calcium carbonate, 6 parts carbon black, and 4 parts nano-silica. The carbon black is N330. The particle size of the nano-calcium carbonate and nano-silica is 30-50 nm.

[0059] Furthermore, the silane coupling agent is composed of γ-mercaptopropyltrimethoxysilane and bis-[γ-(triethoxysilane)propyl]tetrasulfide in a weight ratio of 1:1.

[0060] Furthermore, each part of the additive comprises the following raw materials in parts by weight: 1 part lubricant, 1 part antioxidant, and 0.8 parts light stabilizer.

[0061] Furthermore, the lubricant is zinc stearate. The hindered phenolic antioxidant is composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1. The light stabilizer is 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol.

[0062] In this embodiment, the method for preparing the polyurethane sealant includes the following steps:

[0063] (1) Take the raw materials that make up the polyurethane prepolymer in proportion, carry out the prepolymerization reaction, and obtain the polyurethane prepolymer.

[0064] (2) The polyurethane prepolymer, chain extender, maleic anhydride grafted POE, aromatic polyamide fiber, filler, silane coupling agent, nitrile rubber and additives are placed in a disperser in proportion and mixed at 70°C for 12 min at a speed of 1500 rpm to obtain material A.

[0065] (3) Inject material A into the mold, then put the mold with material A in the curing oven for curing reaction. After material A is completely cured, take it out of the mold to obtain the initial product of the seal.

[0066] (4) The initial seal material after demolding is machined to obtain the required size and shape;

[0067] (5) The initial seal product after turning is post-processed. The post-processing steps include deburring, grinding and cleaning to obtain polyurethane seal.

[0068] Furthermore, in step (1), polyether polyol, polyester polyol and isocyanate are reacted and reacted at 86°C under a nitrogen atmosphere for 3 hours, and then vacuum degassing is performed until no bubbles escape to obtain polyurethane prepolymer. The polyether polyol and polyester polyol have been pre-treated by heating and dehydration.

[0069] Furthermore, in step (3), the mold is heated to 95°C, material A is injected, and cured for 60 minutes under a pressure of 8 MPa and a temperature of 105°C. Then the temperature is raised to 125°C and the pressure is reduced to 2.5 MPa for 100 minutes.

[0070] Example 2

[0071] In this embodiment, a polyurethane sealant comprises the following raw materials in parts by weight: 55 parts of polyurethane prepolymer, 12 parts of chain extender, 16 parts of filler, 5 parts of aromatic polyamide fiber, 4 parts of maleic anhydride-grafted POE, 4 parts of silane coupling agent, 2.5 parts of nitrile rubber, and 2 parts of additives; the preparation method of the polyurethane prepolymer includes the following steps: reacting polyether polyol, polyester polyol and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to hydroxyl groups in the polyether polyol and polyester polyol is 2.1, to obtain the polyurethane prepolymer.

[0072] Furthermore, the isocyanate is composed of toluene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 3:1.

[0073] Furthermore, the polyether polyol is composed of polytetrahydrofuran ether diol and polypropylene oxide diol in a weight ratio of 2:1, and the polyester polyol is polybutylene adipate diol. The weight ratio of the polyether polyol to polybutylene adipate diol is 3:1.

[0074] Furthermore, the chain extender is composed of 1,4-butanediol and 3,3'-dichloro-4,4'-diaminodiphenylmethane in a weight ratio of 4:1.

[0075] Furthermore, each portion of the filler comprises the following raw materials in parts by weight: 9 parts of nano-calcium carbonate, 4 parts of carbon black, and 3 parts of nano-silica.

[0076] Furthermore, the silane coupling agent is bis-[γ-(triethoxysilane)propyl]tetrasulfide.

[0077] Furthermore, each part of the additive comprises the following raw materials in parts by weight: 0.8 parts lubricant, 0.6 parts antioxidant, and 0.6 parts light stabilizer. The carbon black is N330; the particle size of the nano-calcium carbonate and nano-silica is 30-50 nm.

[0078] Furthermore, the lubricant is zinc stearate. The hindered phenolic antioxidant is composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1. The light stabilizer is 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol.

[0079] In this embodiment, the method for preparing the polyurethane sealant includes the following steps:

[0080] (1) Take the raw materials that make up the polyurethane prepolymer in proportion, carry out the prepolymerization reaction, and obtain the polyurethane prepolymer.

[0081] (2) The polyurethane prepolymer, chain extender, maleic anhydride grafted POE, aromatic polyamide fiber, filler, silane coupling agent, nitrile rubber and additives are placed in a disperser in proportion and mixed at 70°C for 10 min at a speed of 1500 rpm to obtain material A.

[0082] (3) Inject material A into the mold, then put the mold with material A in the curing oven for curing reaction. After material A is completely cured, take it out of the mold to obtain the initial product of the seal.

[0083] (4) The initial seal material after demolding is machined to obtain the required size and shape;

[0084] (5) The initial seal product after turning is post-processed. The post-processing steps include deburring, grinding and cleaning to obtain polyurethane seal.

[0085] Furthermore, in step (1), polyether polyol, polyester polyol and isocyanate are reacted and reacted at 86°C under a nitrogen atmosphere for 3 hours, and then vacuum degassing is performed until no bubbles escape to obtain polyurethane prepolymer. The polyether polyol and polyester polyol have been pre-treated by heating and dehydration.

[0086] Furthermore, in step (2), the polyurethane prepolymer, chain extender, maleic anhydride grafted POE, aromatic polyamide fiber, filler, silane coupling agent and additives are placed in a high-speed disperser and mixed at 65°C for 15 minutes at a speed of 1400 rpm to obtain material A.

[0087] Furthermore, in step (3), the mold is heated to 100°C, material A is injected, and cured for 50 minutes under a pressure of 9 MPa and a temperature of 110°C. Then, the temperature is raised to 120°C and the pressure is reduced to 2 MPa to cure for 100 minutes.

[0088] The rest of this embodiment is the same as that in Embodiment 1.

[0089] Example 3

[0090] In this embodiment, a polyurethane sealant comprises the following raw materials in parts by weight: 65 parts of polyurethane prepolymer, 16 parts of chain extender, 18 parts of filler, 7 parts of aromatic polyamide fiber, 6 parts of maleic anhydride-grafted POE, 5 parts of silane coupling agent, 3.5 parts of nitrile rubber, and 3 parts of additives; the preparation method of the polyurethane prepolymer includes the following steps: reacting polyether polyol, polyester polyol and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to hydroxyl groups in the polyether polyol and polyester polyol is 2.1, to obtain the polyurethane prepolymer.

[0091] Furthermore, the isocyanate is composed of toluene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 3:1.

[0092] Furthermore, the polyether polyol is composed of polytetrahydrofuran ether diol and polypropylene oxide diol in a weight ratio of 2.5:1, and the polyester polyol is polybutylene adipate diol. The weight ratio of the polyether polyol to polybutylene adipate diol is 3.5:1.5.

[0093] Furthermore, the chain extender is composed of 1,4-butanediol and 3,3'-dichloro-4,4'-diaminodiphenylmethane in a weight ratio of 4:1.

[0094] Furthermore, each portion of the filler comprises the following raw materials in parts by weight: 10 parts of nano-calcium carbonate, 4 parts of carbon black, and 4 parts of nano-silica.

[0095] Furthermore, the silane coupling agent is composed of γ-mercaptopropyltrimethoxysilane and bis-[γ-(triethoxysilane)propyl]tetrasulfide in a weight ratio of 1.5:1.

[0096] Furthermore, each part of the additive comprises the following raw materials in parts by weight: 1.2 parts lubricant, 1 part antioxidant, and 0.8 parts light stabilizer.

[0097] Furthermore, the silane coupling agent is γ-mercaptopropyltrimethoxysilane.

[0098] Furthermore, the lubricant is zinc stearate. The hindered phenolic antioxidant is composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1. The light stabilizer is 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol.

[0099] In this embodiment, the method for preparing the polyurethane sealant includes the following steps:

[0100] (1) Take the raw materials that make up the polyurethane prepolymer in proportion, carry out the prepolymerization reaction, and obtain the polyurethane prepolymer.

[0101] (2) The polyurethane prepolymer, chain extender, maleic anhydride grafted POE, aromatic polyamide fiber, filler, silane coupling agent, nitrile rubber and additives are placed in a disperser in proportion and mixed at 75°C for 8 minutes at a speed of 1500 rpm to obtain material A.

[0102] (3) Inject material A into the mold, then put the mold with material A in the curing oven for curing reaction. After material A is completely cured, take it out of the mold to obtain the initial product of the seal.

[0103] (4) The initial seal material after demolding is machined to obtain the required size and shape;

[0104] (5) The initial seal product after turning is post-processed. The post-processing steps include deburring, grinding and cleaning to obtain polyurethane seal.

[0105] Furthermore, in step (1), polyether polyol, polyester polyol and isocyanate are reacted and reacted at 86°C under a nitrogen atmosphere for 3 hours, and then vacuum degassing is performed until no bubbles escape to obtain polyurethane prepolymer. The polyether polyol and polyester polyol have been pre-treated by heating and dehydration.

[0106] Furthermore, in step (3), the mold is heated to 95°C, material A is injected, and cured for 60 minutes under a pressure of 8 MPa and a temperature of 105°C. Then the temperature is raised to 125°C and the pressure is reduced to 2.5 MPa for 100 minutes.

[0107] The rest of this embodiment is the same as that in Embodiment 1.

[0108] Comparative Example 1

[0109] The difference between this comparative example and Example 1 is that in this comparative example, a polyurethane sealant comprises the following raw materials in parts by weight: 66 parts polyurethane prepolymer, 15 parts chain extender, 20 parts filler, 6 parts maleic anhydride-grafted POE, 4 parts silane coupling agent, 3 parts nitrile rubber, and 2.8 parts additives; the preparation method of the polyurethane prepolymer includes the following steps: reacting polyether polyol, polyester polyol, and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to the hydroxyl groups in the polyether polyol and polyester polyol is 2.1, to obtain the polyurethane prepolymer. That is, this comparative example does not contain aromatic polyamide fibers, but uses an equal amount of polyurethane prepolymer instead.

[0110] The rest of the contents of this comparative example are the same as those of Example 1, and will not be repeated here.

[0111] Comparative Example 2

[0112] The difference between this comparative example and Example 1 is that in this comparative example, a polyurethane sealant comprises the following raw materials in parts by weight: 66 parts polyurethane prepolymer, 15 parts chain extender, 20 parts filler, 6 parts aromatic polyamide fiber, 4 parts silane coupling agent, 3 parts nitrile rubber, and 2.8 parts additives; the preparation method of the polyurethane prepolymer includes the following steps: reacting polyether polyol, polyester polyol, and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to the hydroxyl groups in the polyether polyol and polyester polyol is 2.1, to obtain the polyurethane prepolymer. That is, this comparative example does not contain maleic anhydride-grafted POE, but uses an equal amount of polyurethane prepolymer instead.

[0113] The performance of the polyurethane seals prepared in Examples 1-3 and Comparative Examples 1-2 was tested, and the test results are shown in Table 1 below:

[0114]

[0115]

[0116] The abrasion resistance of this invention was tested according to ASTM D4060 using a Taber abrasion tester at a speed of 60 r / min. Tear strength was tested according to GB / T 529-2008. Tensile strength was tested according to GB / T 528-2009. Elongation at break was tested according to GB / T 13477.8-2017. Oil resistance was tested using the IRM903 oil volume change test. Before testing, the polyurethane sealant was immersed in IRM903 oil for 72 hours at 70°C, and the test was conducted according to ASTM D471. Compression set was tested according to GB / T7759.1-2015.

[0117] In summary, the polyurethane seal of the present invention incorporates aromatic polyamide fibers, maleic anhydride-grafted POE, silane coupling agents, fillers, chain extenders, nitrile rubber, and other raw materials into a polyurethane prepolymer system. The various raw materials work together synergistically to produce polyurethane seals with excellent wear resistance, tear strength, tensile strength, oil resistance, and low compression set. It can effectively reduce friction loss and wear in reciprocating or rotating sealing applications, has a wide range of applications, and good durability.

[0118] The specific embodiments described above are further illustrations of the technical solution and beneficial effects of the present invention, and are not intended to limit the implementation methods. For those skilled in the art, any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A polyurethane seal, characterized in that: The raw materials include the following parts by weight: 40-70 parts of polyurethane prepolymer, 5-20 parts of chain extender, 10-30 parts of filler, 4-8 parts of aromatic polyamide fiber, 4-8 parts of maleic anhydride-grafted POE, 3-6 parts of silane coupling agent, 2-5 parts of nitrile rubber, and 1-5 parts of additives; each part of the additives includes the following parts by weight of raw materials: 0.5-2 parts of lubricant, 0.5-1.5 parts of antioxidant, and 0.5-1.5 parts of light stabilizer; the preparation method of the polyurethane prepolymer includes the following steps: reacting polyether polyol, polyester polyol and isocyanate, wherein the molar ratio of isocyanate groups in the isocyanate to hydroxyl groups in the polyether polyol and polyester polyol is 2.1-2.3, to obtain the polyurethane prepolymer.

2. The polyurethane seal according to claim 1, characterized in that: The isocyanate is at least one of toluene diisocyanate and diphenylmethane diisocyanate.

3. The polyurethane seal according to claim 1, characterized in that: The polyether polyol is at least one of polytetrahydrofuran ether diol and polypropylene oxide diol, and the polyester polyol is at least one of polybutylene adipate diol and polycarbonate diol.

4. The polyurethane seal according to claim 1, characterized in that: The chain extender is at least one of 1,4-butanediol and 3,3'-dichloro-4,4'-diaminodiphenylmethane.

5. The polyurethane seal according to claim 1, characterized in that: The filler is at least one of nano-calcium carbonate, carbon black, and nano-silica.

6. The polyurethane seal according to claim 1, characterized in that: Each portion of the filler comprises the following raw materials in parts by weight: 8-12 parts of nano-calcium carbonate, 4-7 parts of carbon black, and 3-6 parts of nano-silica.

7. A method for preparing a polyurethane seal as described in any one of claims 1-6, characterized in that: Includes the following steps: (1) Take the raw materials that make up the polyurethane prepolymer in proportion, carry out the prepolymerization reaction, and obtain the polyurethane prepolymer; (2) The polyurethane prepolymer, chain extender, maleic anhydride grafted POE, aromatic polyamide fiber, filler, silane coupling agent, and nitrile rubber are placed in a disperser and mixed and reacted at a temperature of 65-75℃ to obtain material A. (3) Inject material A into the mold, and then put the mold with material A in the curing oven to carry out the curing reaction. After material A is completely cured, take it out of the mold to obtain the initial product of the seal. (4) The initial seal material after demolding is machined to obtain the required size and shape; (5) The initial seal after turning is post-processed. The post-processing steps include deburring, grinding and cleaning to obtain polyurethane seal.

8. The method for preparing a polyurethane seal according to claim 7, characterized in that: In step (1), polyether polyol, polyester polyol and isocyanate are reacted and reacted under nitrogen atmosphere protection at 85-90℃ for 2.5-3.5h, and then vacuum degassing is performed to obtain polyurethane prepolymer.

9. The method for preparing a polyurethane seal according to claim 7, characterized in that: In step (3), the mold is heated to 90-105℃, material A is injected, and cured for 40-80 minutes under the conditions of 6-10MPa pressure and 105-115℃ temperature. Then the temperature is raised to 120-130℃ and the pressure is reduced to 2-3MPa for 60-120 minutes.

Images