A low-temperature resistant polyurethane sealing material, its preparation method and application

Abstract

The present invention provides a low-temperature resistant polyurethane sealing material, its preparation method and application, which include the following components in parts by mass: 20-50 parts by mass of vinyl monomer-grafted polyester polyol, 60-100 parts by mass of polyester polyol, 30-70 parts by mass of isocyanate, 5-20 parts by mass of chain extender, and 0.2-0.8 parts by mass of catalyst. The low-temperature resistant polyurethane sealing material prepared by the present invention has good hydrolysis resistance (high tensile strength retention rate and elongation at break retention rate), good low-temperature resistance (low glass transition temperature reduction), as well as high resilience rate and low abrasion loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyurethane seals, and particularly relates to a low-temperature resistant polyurethane sealing material, a preparation method thereof, and an application thereof. Background Art

[0002] Polyurethane (PU) is a macromolecular compound. Due to the good interfacial adhesion ability and bonding performance of polyurethane materials, and at the same time having characteristics such as large elongation at break, good elasticity, wear resistance, excellent weather resistance, low-temperature toughness, and long service life. Thus, products such as polyurethane plastics, polyurethane fibers, polyurethane rubbers, and polyurethane elastomers made of polyurethane materials are widely used in the fields of home furnishing, construction, daily necessities, transportation, and household appliances.

[0003] With the development of China's hydraulic and pneumatic industries, the consumption of seals has been increasing continuously. Since the polyurethane elastomer structure contains extremely polar groups, hydrogen bonds can be formed within and between molecules of the polyurethane elastomer. Under the action of hydrogen bonds, physical cross-linking can occur inside the polyurethane elastomer, making the polyurethane elastomer have excellent wear resistance, mechanical properties, tear resistance, and oil resistance, and is widely used as a seal material in hydraulic and control systems.

[0004] Polyurethane elastomer is a block polymer, and its molecular chain is generally composed of two parts. At room temperature, one part is in a high elastic state, called the soft segment; the other part is in a glassy state or crystalline state, called the hard segment. Generally, the soft segment is composed of a flexible long chain of polymer polyol, and the polyurethane polyols used usually include polyester polyols, polyether polyols, polyolefin polyols, etc.

[0005] Among them, in the polyester-type polyurethane material made of polyester polyol, not only can hydrogen bonds be formed between hard segments, but also the polar groups on the soft segment can partially form hydrogen bonds with the polar groups on the hard segment, enabling the hard segment phase to be more evenly distributed in the soft segment phase, playing the role of elastic cross-linking points. Moreover, the strength, oil resistance, and thermal-oxidative aging resistance of the prepared polyester-type polyurethane material are all higher than those of polyether-type polyurethane materials, and the price is moderate, so it is widely used as the raw material of polyester-type polyurethane materials. However, the polyester-type polyurethane material made of polyester polyol also has disadvantages such as poor hydrolysis resistance and poor low-temperature performance. Therefore, how to improve the hydrolysis resistance and low-temperature performance of polyester-type polyurethane is an urgent problem to be solved in the present invention. Summary of the Invention

[0006] The purpose of the present invention is to provide a low-temperature resistant polyurethane sealing material, a preparation method thereof, and an application thereof, so as to solve the problem of how to improve the hydrolysis resistance and low-temperature performance of polyester-type polyurethane proposed in the above background art.

[0007] To achieve the above object, the present invention provides the following technical solutions: On the one hand, the present invention provides a low-temperature resistant polyurethane sealing material, comprising the following components in parts by mass: 20-50 parts by mass of vinyl monomer grafted polyester polyol (for example, it can be one of 20, 30, 40 or 50), 60-100 parts by mass of polyester polyol (for example, it can be one of 60, 70, 80, 90 or 100), 30-70 parts by mass of isocyanate (for example, it can be one of 30, 35, 40, 50, 60 or 70), 5-20 parts by mass of chain extender (for example, it can be one of 5, 10, 15 or 20), and 0.2-0.8 parts by mass of catalyst (for example, it can be one of 0.2, 0.4, 0.6 or 0.8).

[0008] As a further improvement, the polyester polyol is a polyester diol, and the molecular weight of the polyester diol is 600-2000 (for example, it can be one of 600, 800, 1000, 1200, 1500 or 2000), and the polyester diol can be provided by Mitsubishi Chemical Corporation, for example.

[0009] As a further improvement, the isocyanate is a diisocyanate, and the diisocyanate is one or two of 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate. 1,5-naphthalene diisocyanate can be provided by Cosmonate ND of Mitsui, Japan, for example, p-phenylene diisocyanate can be provided by Youbang Chemical Co., Ltd. in Lishui, Zhejiang, and diphenylmethane diisocyanate can be provided by Tosoh Corporation, Japan, for example.

[0010] As a further improvement, the chain extender is at least one of 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethyltoluenediamine, dimethylthiotoluenediamine, and the chain extender can be provided by Mitsubishi Chemical Corporation, for example.

[0011] As a further improvement, the catalyst is at least one of butyltin oxide, dibutyltin dibutyrate, dimethyltin dibutyrate, dioctyltin dibutyrate, dibutyltin diacetate, and the catalyst can be provided by Dow Chemical Company, for example.

[0012] As a further improvement, a method for preparing vinyl monomer-grafted polyester polyol includes the following steps: Add 20-40 (for example, one of 20, 21, 25, 30, 35 or 40) parts by mass of vinyl monomer, 60-90 (for example, one of 60, 70, 80 or 90) parts by mass of polyester polyol, 1-3 (for example, one of 1, 1.5, 2, 2.5 or 3) parts by mass of initiator, and 0.5-1 (for example, one of 0.5, 0.6, 0.7, 0.8, 0.9 or 1) parts by mass of catalyst into a reaction kettle for reaction. The reaction temperature is 100-120 (for example, one of 100, 105, 110, 115 or 120) °C, and the reaction time is 1-3 h to obtain vinyl monomer-grafted polyester polyol.

[0013] As a further improvement, the vinyl monomer includes styrene, acrylonitrile and methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene, and the mass ratio of styrene, acrylonitrile and methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene is (0.5-1):(1-2):(5-10) (for example, one of 0.5:1:5, 0.5:2:5, 0.5:1:8, 0.5:2:8, 1:1:5, 1:1:7, 1:1.5:6 or 1:2:10). Styrene and acrylonitrile can be provided by Wuxi Huimengyuan Chemical Co., Ltd. for example.

[0014] As a further improvement, the initiator is at least one of azobisisobutyronitrile or benzoyl peroxide, and the initiator can be provided by BASF of Germany for example.

[0015] As a further improvement, a method for preparing methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene includes the following steps:

[0016] A) Add 90-120 (for example, one of 90, 95, 100, 105, 110 or 120) parts by mass of chlorinated polyethylene and 1-2 (for example, one of 1, 1.2, 1.5, 1.8 or 2) parts by mass of tetraethylammonium chloride into a reaction kettle for mixing. The mixing temperature is 60-90 (for example, one of 60, 70, 80 or 90) °C, and the mixing time is 2-3 h;

[0017] B) Continuing to add 30 - 60 (for example, it can be one of 30, 35, 40, 45, 50 or 60) parts by mass of methacryloxypropyltrimethoxysilane, 2 - 3 (for example, it can be one of 2, 2.2, 2.5, 2.8 or 3) parts by mass of stearic acid amide, and 0.5 - 2 (for example, it can be one of 0.5, 0.8, 1, 1.5 or 2) parts by mass of antioxidant 1010 to step A), fully mixing them, and extruding them in an extruder to obtain methacryloxypropyltrimethoxysilane - grafted chlorinated polyethylene.

[0018] Chlorinated polyethylene can be provided by, for example, Hangzhou Yuxian Chemical Co., Ltd.; tetraethylammonium chloride can be provided by, for example, Shandong New Kinetic Energy Chemical Co., Ltd.; methacryloxypropyltrimethoxysilane can be provided by, for example, a powerful supplier in Dongguan Shanyi Plasticization, with the product number KH - 570; stearic acid amide can be provided by, for example, Croda in the UK; antioxidant 1010 can be provided by, for example, BASF in Germany.

[0019] On the other hand, the present invention also provides a preparation method of a low - temperature - resistant polyurethane sealing material, including the following steps:

[0020] (1) Reacting an alkenyl monomer - grafted polyester polyol, a polyester polyol, an isocyanate and a catalyst at 70 - 90 (for example, it can be one of 70, 75, 80, 85 or 90) °C for 2 - 4 h to obtain a polyurethane prepolymer;

[0021] (2) Adding a chain extender to step (1) for a mixing reaction for 2 - 4 h, then pouring the mixture into a mold, curing it at 90 - 110 (for example, it can be one of 90, 95, 100, 105 or 110) °C, demolding it after curing for 1 - 3 h, and then vulcanizing it at 100 - 120 (for example, it can be one of 100, 105, 110, 115 or 120) °C for 5 - 8 h to obtain a low - temperature - resistant polyurethane sealing material.

[0022] On the other hand, the present invention also provides an application of a self - lubricating polyurethane elastomer material in the preparation of hydraulic seals.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The low - temperature - resistant polyurethane sealing material prepared by the present invention has good hydrolysis resistance (high tensile strength retention rate and elongation at break retention rate), good low - temperature performance (low reduced glass transition temperature), as well as a high rebound rate and a low wear amount. Specific embodiments

[0024] The present invention will be described below in conjunction with specific implementation embodiments. It should be noted that the following embodiments are examples of the present invention, only for explaining the present invention, and not for limiting the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0025] Example 1:

[0026] A method for preparing methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene, comprising the following steps:

[0027] A) Add 90 parts by mass of chlorinated polyethylene and 1.5 parts by mass of tetraethylammonium chloride to a reaction kettle for mixing, the mixing temperature is 70 °C, and the mixing time is 2.5 h;

[0028] B) Continuously add 35 parts by mass of methacryloxypropyltrimethoxysilane, 2.5 parts by mass of stearic acid amide, and 1 part by mass of antioxidant 1010 to step A) for sufficient mixing, and extrude in an extruder to obtain methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene.

[0029] A method for preparing vinyl monomer-grafted polyester diol, comprising the following steps:

[0030] Add 5 parts by mass of styrene, 5 parts by mass of acrylonitrile, 25 parts by mass of methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene, 80 parts by mass of polyester diol, 2 parts by mass of azobisisobutyronitrile, and 0.8 parts by mass of dioctyltin dibutyrate to a reaction kettle for reaction, the reaction temperature is 110 °C, and the reaction time is 2 h to obtain vinyl monomer-grafted polyester diol.

[0031] A method for preparing a low-temperature resistant polyurethane sealing material, comprising the following steps:

[0032] (1) React 20 parts by mass of vinyl monomer-grafted polyester diol, 90 parts by mass of polyester diol, 40 parts by mass of 1,5-naphthalene diisocyanate, 5 parts by mass of butyl benzyl phthalate, and 0.6 parts by mass of dioctyltin dibutyrate at 80 °C for 2.5 h to obtain a polyurethane prepolymer;

[0033] (2) Add 10 parts by mass of 1,4-butanediol to step (1) for mixing reaction, the mixing time is 3 h, then pour the mixture into a mold, cure at 100 °C, demold after 2 h of curing, and then vulcanize at 120 °C for 6 h to obtain a low-temperature resistant polyurethane sealing material, wherein the polyester diol used in this example has a molecular weight of 800.

[0034] Example 2:

[0035] Preparation method of methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene, comprising the following steps:

[0036] A) Add 90 parts by mass of chlorinated polyethylene and 1 part by mass of tetraethylammonium chloride to a reaction kettle for mixing, the mixing temperature is 70 °C, and the mixing time is 2 h;

[0037] B) Continuously add 40 parts by mass of methacryloxypropyltrimethoxysilane, 2.5 parts by mass of stearic acid amide, and 1.5 parts by mass of antioxidant 1010 to step A), mix well, and extrude in an extruder to obtain methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene.

[0038] Preparation method of vinyl monomer-grafted polyester diol, comprising the following steps:

[0039] Add 1 part by mass of styrene, 4 parts by mass of acrylonitrile, 16 parts by mass of methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene, 80 parts by mass of polyester polyol, 2 parts by mass of benzoyl peroxide, and 1 part by mass of dibutyltin diacetate to a reaction kettle for reaction, the reaction temperature is 110 °C, and the reaction time is 2 h to obtain vinyl monomer-grafted polyester diol.

[0040] Preparation method of low-temperature resistant polyurethane sealing material, comprising the following steps:

[0041] (1) React 25 parts by mass of vinyl monomer-grafted polyester diol, 90 parts by mass of polyester diol, 42 parts by mass of p-phenylene diisocyanate, 6 parts by mass of butyl benzyl phthalate, and 0.5 part by mass of dimethyltin dibutyrate at 80 °C for 2.5 h to obtain a polyurethane prepolymer;

[0042] (2) Add 15 parts by mass of neopentyl glycol to step (1) for mixing reaction, the mixing time is 4 h, then pour the mixture into a mold, cure at 105 °C, demold after curing for 3 h, and then vulcanize at 110 °C for 6 h to obtain a low-temperature resistant polyurethane sealing material, wherein the molecular weight of the polyester diol used in this example is 1000.

[0043] Example 3:

[0044] Preparation method of methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene, comprising the following steps:

[0045] A) Add 100 parts by mass of chlorinated polyethylene and 1 part by mass of tetraethylammonium chloride to a reaction kettle for mixing, the mixing temperature is 80 °C, and the mixing time is 2 h;

[0046] (B) Continuing to add 40 parts by mass of methacryloxypropyltrimethoxysilane, 2.5 parts by mass of stearic acid amide, and 1.5 parts by mass of antioxidant 1010 to step (A), fully mixing, and extruding in an extruder to obtain methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene.

[0047] A preparation method of an alkenyl monomer-grafted polyester diol includes the following steps:

[0048] Adding 5 parts by mass of styrene, 5 parts by mass of acrylonitrile, 25 parts by mass of methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene, 70 parts by mass of polyester diol, 1 part by mass of azobisisobutyronitrile, 1 part by mass of benzoyl peroxide, and 0.8 part by mass of catalyst to a reaction kettle for reaction. The reaction temperature is 105 °C, and the reaction time is 2 h to obtain an alkenyl monomer-grafted polyester diol.

[0049] A preparation method of a low-temperature resistant polyurethane sealing material includes the following steps:

[0050] (1) Reacting 30 parts by mass of alkenyl monomer-grafted polyester diol, 100 parts by mass of polyester diol, 35 parts by mass of diphenylmethane diisocyanate, 5 parts by mass of diisobutyl phthalate, and 0.6 part by mass of dimethyltin dibutyrate at 75 °C for 3 h to obtain a polyurethane prepolymer;

[0051] (2) Adding 15 parts by mass of 1,6-hexanediol to step (1) for mixing reaction. The mixing time is 4 h, then pouring the mixture into a mold, curing at 105 °C, demolding after 3 h of curing, and then vulcanizing at 115 °C for 6 h to obtain a low-temperature resistant polyurethane sealing material. Among them, the polyester diol used in this example has a molecular weight of 1200.

[0052] Example 4:

[0053] The preparation method of methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene and the preparation method of alkenyl monomer-grafted polyester polyol are the same as those in Example 1, and the components used and the mass parts of each component are the same as those in Example 1.

[0054] A preparation method of a low-temperature resistant polyurethane sealing material includes the following steps:

[0055] (1) Reacting 40 parts by mass of alkenyl monomer-grafted polyester diol, 80 parts by mass of polyester diol, 40 parts by mass of diphenylmethane diisocyanate, 6 parts by mass of diisobutyl phthalate, and 0.8 part by mass of dimethyltin dibutyrate at 85 °C for 2 h to obtain a polyurethane prepolymer;

[0056] (2) 20 parts by mass of 1,6 - hexanediol was added to step (1) for mixing reaction. The mixing time was 3 h. Then the mixture was poured into a mold and cured at 105 °C. After curing for 3 h, it was demolded and then vulcanized at 120 °C for 5 h to obtain a low - temperature resistant polyurethane sealing material. Among them, the molecular weight of the polyester diol used in this example was 2000.

[0057] Example 5:

[0058] The preparation method of methacryloxypropyltrimethoxysilane - grafted chlorinated polyethylene, the preparation method of vinyl monomer - grafted polyester polyol, and the preparation method of low - temperature resistant polyurethane sealing material are the same as those in Example 1. The components used and the mass parts of each component are basically the same as those in Example 1, except that: styrene is 5 parts by mass, acrylonitrile is 10 parts by mass, and methacryloxypropyltrimethoxysilane - grafted chlorinated polyethylene is 20 parts by mass.

[0059] Example 6:

[0060] The preparation method of methacryloxypropyltrimethoxysilane - grafted chlorinated polyethylene, the preparation method of vinyl monomer - grafted polyester polyol, and the preparation method of low - temperature resistant polyurethane sealing material are the same as those in Example 1. The components used and the mass parts of each component are basically the same as those in Example 1, except that: styrene is 2.3 parts by mass, acrylonitrile is 4.6 parts by mass, and methacryloxypropyltrimethoxysilane - grafted chlorinated polyethylene is 28.1 parts by mass.

[0061] Comparative Example 1:

[0062] The preparation method of methacryloxypropyltrimethoxysilane - grafted chlorinated polyethylene, the preparation method of vinyl monomer - grafted polyester polyol, and the preparation method of low - temperature resistant polyurethane sealing material are the same as those in Example 1. The components used and the mass parts of each component are basically the same as those in Example 1, except that: methacryloxypropyltrimethoxysilane - grafted chlorinated polyethylene was replaced with chlorinated polyethylene.

[0063] Comparative Example 2:

[0064] The preparation method of low - temperature resistant polyurethane sealing material is the same as that in Example 1. The components used and the mass parts of each component are basically the same as those in Example 1, except that: no vinyl monomer is added.

[0065] Comparative Example 3:

[0066] The preparation method of low - temperature resistant polyurethane sealing material is the same as that in Example 1. The components used and the mass parts of each component are basically the same as those in Example 1, except that: 90 parts by mass of polyester diol and 20 parts by mass of vinyl monomer - grafted polyester diol were replaced with 110 parts by mass of polyethylene glycol, and the polyethylene glycol used was provided by Mitsubishi Chemical Corporation with a molecular weight of 800.

[0067] The testing methods are as follows:

[0068] Hydrolysis resistance test: The temperature is 70 °C, the relative humidity is 95%, and the test period is 168 h;

[0069] Tensile strength retention rate: Test according to the DIN 53504 standard;

[0070] Elongation at break retention rate: Test according to the DIN 53504 standard.

[0071] Glass transition temperature: Test using a 204 type differential scanning calorimeter produced by Netzsch, Germany.

[0072] Test conditions: Heat the sample from room temperature to 180 °C under N2 protection, hold at a constant temperature for 5 minutes to eliminate the thermal history, cool to -70 °C and then heat to 180 °C again.

[0073] Rebound resilience test: Test according to the DIN 53512 standard.

[0074] Abrasion loss test: Test according to the DIN 53516 standard.

[0075] The test results are shown in Table 1, as follows:

[0076]

[0077]

[0078] It can be seen from the comparison between Example 1, Comparative Example 1 and Comparative Example 2 that when no vinyl monomer-grafted polyester diol is added, the hydrolysis resistance of the prepared low-temperature resistant polyurethane sealing material is poor (the tensile strength retention rate is only 70%, and the elongation at break retention rate is only 68%), and the low-temperature resistance is also poor (the glass transition temperature is only -39°C). In order to improve the hydrolysis resistance and lower glass transition temperature of the low-temperature resistant polyurethane sealing material, by using vinyl monomer-grafted polyester diol, and the vinyl monomers are styrene, acrylonitrile, and chlorinated polyethylene, the tensile strength retention rate of the prepared low-temperature resistant polyurethane sealing material is 84%, the elongation at break retention rate is 70%, and the glass transition temperature is -43°C. Although the hydrolysis resistance is improved and the glass transition temperature is decreased, it still cannot meet the actual needs. The tensile strength retention rate of the low-temperature resistant polyurethane sealing material prepared by replacing chlorinated polyethylene with methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene in this application is 92%, the elongation at break retention rate is 112%, and the glass transition temperature is -60°C; from this, it can be seen that the low-temperature resistant polyurethane sealing material prepared by using methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene in the present invention not only has good hydrolysis resistance (high tensile strength retention rate and elongation at break retention rate), lower glass transition temperature, but also has a higher rebound rate and lower wear amount.

[0079] It can be seen from the comparison between Example 1 and Comparative Example 3 that the tensile strength retention rate of the polyurethane sealing material prepared by replacing polyester diol and vinyl monomer-grafted polyester diol with polyethylene glycol is 86%, the elongation at break retention rate is 95%, the glass transition temperature is -52°C, and the rebound rate is only 58%, and the wear amount is only 45 mm 3 , while the tensile strength retention rate of the polyurethane sealing material prepared by using the polyester diol and vinyl monomer-grafted polyester diol of this application is 92%, the elongation at break retention rate is 112%, the glass transition temperature is -60°C, and the rebound rate is only 75%, and the wear amount is only 21 mm 3 ; from this, it can be seen that the polyester-type polyurethane sealing material prepared in this application compared with the polyether-type polyurethane sealing material not only has better hydrolysis resistance (high tensile strength retention rate and elongation at break retention rate), lower glass transition temperature, but also has a higher rebound rate and lower wear amount.

[0080] From the comparison among Example 1, Example 5 and Example 6, it can be seen that when the styrene in the vinyl monomer is 5 parts by mass, acrylonitrile is 10 parts by mass and the grafted chlorinated polyethylene of methacryloxypropyltrimethoxysilane is 20 parts by mass, the tensile strength retention rate of the low-temperature resistant polyurethane sealing material prepared is 87%, the elongation at break retention rate is only 103%, and the glass transition temperature is -57°C. When the styrene in the vinyl monomer is 2.3 parts by mass, acrylonitrile is 4.6 parts by mass and the grafted chlorinated polyethylene of methacryloxypropyltrimethoxysilane is 28.1 parts by mass, the tensile strength retention rate of the low-temperature resistant polyurethane sealing material prepared is 88%, the elongation at break retention rate is only 98%, and the glass transition temperature is -56°C. When the styrene in the vinyl monomer is 5 parts by mass, acrylonitrile is 5 parts by mass and the grafted chlorinated polyethylene of methacryloxypropyltrimethoxysilane is 25 parts by mass, the tensile strength retention rate of the low-temperature resistant polyurethane sealing material prepared is 92%, the elongation at break retention rate is 112%, and the glass transition temperature is -60°C. It can be seen therefrom that when the mass ratio of styrene, acrylonitrile and the grafted chlorinated polyethylene of methacryloxypropyltrimethoxysilane in the vinyl monomer of the present invention is (0.5 - 1):(1 - 2):(5 - 10), the prepared low-temperature resistant polyurethane sealing material has better hydrolysis resistance (high tensile strength retention rate and elongation at break retention rate), lower reduced glass transition temperature, higher resilience rate and lower abrasion loss.

[0081] From Example 1 to Example 4, it can be seen that under different reaction conditions, for the low-temperature resistant polyurethane sealing material prepared with the vinyl monomer being styrene, acrylonitrile and the grafted chlorinated polyethylene of methacryloxypropyltrimethoxysilane and the mass ratio of styrene, acrylonitrile and the grafted chlorinated polyethylene of methacryloxypropyltrimethoxysilane being (0.5 - 1):(1 - 2):(5 - 10), it has good hydrolysis resistance (high tensile strength retention rate and elongation at break retention rate), good low-temperature resistance (low reduced glass transition temperature), higher resilience rate and lower abrasion loss.

[0082] In summary, the low-temperature resistant polyurethane sealing material prepared by the present invention has good hydrolysis resistance (high tensile strength retention rate and elongation at break retention rate), good low-temperature resistance (low reduced glass transition temperature), as well as higher resilience rate and lower abrasion loss.

[0083] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A low-temperature resistant polyurethane sealing material, characterized in that: The invention comprises the following components in parts by weight: 20-50 parts by weight of vinyl monomer grafted polyester polyol, 60-100 parts by weight of polyester polyol, 30-70 parts by weight of isocyanate, 5-20 parts by weight of chain extender, and 0.2-0.8 parts by weight of catalyst; The preparation method of the vinyl monomer grafted polyester polyol comprises the following steps: adding 20-40 parts by mass of vinyl monomer, 60-90 parts by mass of polyester polyol, 1-3 parts by mass of initiator, and 0.5-1 parts by mass of catalyst into a reaction kettle for reaction at a reaction temperature of 100-120° C. for a reaction time of 1-3 hours to obtain the vinyl monomer grafted polyester polyol; The olefin monomers include styrene, acrylonitrile and methacryloyloxypropyl trimethoxysilane grafted chlorinated polyethylene, and the mass ratio of styrene, acrylonitrile and methacryloyloxypropyl trimethoxysilane grafted chlorinated polyethylene is (0.5-1): (1-2): (5-10); The preparation method of methacryloxypropyltrimethoxysilane grafted chlorinated polyethylene comprises the following steps: A) adding 90-120 parts by weight of chlorinated polyethylene and 1-2 parts by weight of tetraethylammonium chloride into a reaction kettle and mixing them at a mixing temperature of 60-90° C. for 2-3 hours; B) 30-60 parts by weight of methacryloxypropyltrimethoxysilane, 2-3 parts by weight of stearic acid amide and 0.5-2 parts by weight of antioxidant 1010 are added to step A), the mixture is fully mixed, and the mixture is extruded in an extruder to obtain methacryloxypropyltrimethoxysilane-grafted chlorinated polyethylene.

2. The low-temperature resistant polyurethane sealing material according to claim 1, wherein: The polyester polyol is a polyester diol, and the molecular weight of the polyester diol is 600-2000.

3. A low-temperature resistant polyurethane sealing material according to claim 1, characterized in that: The isocyanate is a diisocyanate, and the diisocyanate is one or two of 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, and diphenylmethane diisocyanate.

4. A low-temperature resistant polyurethane sealing material according to claim 1, characterized in that: The chain extender is at least one of 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethyltoluenediamine, and dimethylthiotoluenediamine.

5. A low-temperature resistant polyurethane sealing material according to claim 1, characterized in that: The catalyst is at least one of butyl tin oxide, dibutyl tin dibutyrate, dimethyl tin dibutyrate, dioctyl tin dibutyrate and dibutyl tin diacetate.

6. A method for preparing a low-temperature resistant polyurethane sealing material according to any one of claims 1-5, characterized in that: The following steps are involved: (1) reacting vinyl monomer grafted polyester polyol, polyester polyol, isocyanate and catalyst at 70-90° C. for 2-4 hours to obtain a polyurethane prepolymer; (2) adding a chain extender to the step (1) for a mixing reaction, the mixing time being 2-4 hours, then pouring the mixture into a mold, curing at 90-110° C., demolding after curing for 1-3 hours, and then vulcanizing at 100-120° C. for 5-8 hours to obtain a low-temperature resistant polyurethane sealing material.

7. Use of the low-temperature resistant polyurethane sealing material according to any one of claims 1 to 5 in the preparation of hydraulic seals.

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