High-strength low-temperature-resistant organosilicon polyurethane resin and preparation method thereof

Abstract

The invention provides high-strength low-temperature-resistant organosilicon polyurethane resin and a preparation method thereof, and belongs to the technical field of polyurethane materials. The organic silicon polyurethane resin provided by the invention takes dihydroxy polysiloxane and diisocyanate as base materials, an aryl chain extender is introduced, and the influence of low-temperature crystallization of a polymer is reduced by utilizing a soft and hard segment staggered structure, specifically, polydimethylsiloxane is used as a soft segment, diisocyanate and the chain extender react to serve as a hard segment, and the organic silicon polyurethane resin is prepared. The soft and hard segment alternate structure of the polymer can reduce the chain segment crystallization of the polydimethylsiloxane, so that the low-temperature performance of the polydimethylsiloxane is improved, and the polydimethylsiloxane shows very good flexibility at extremely low temperature. Besides, a mismatched supramolecular structure can be formed among molecules of the chain extender, and the acting force in / between molecular chains is enhanced, so that the strength and the toughness of an elastomer are improved, and finally, the high-performance polyurethane resin with high strength, high toughness and low temperature resistance is obtained, so that the reliability and the durability of a low-temperature-resistant polyurethane protective material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane materials, and particularly relates to a high-strength and low-temperature-resistant organosilicon polyurethane resin and a preparation method thereof. Background Art

[0002] Polydimethylsiloxane (PDMS) is a typical organosilicon polymer, which has physiological inertness, good chemical stability, electrical insulation, weather resistance and high shear resistance, and has a wide viscosity range, low freezing point, high flash point and good hydrophobic performance. It can be used for a long time within the temperature range of 50-180°C and is widely used in industries such as chemical engineering, textile, printing and dyeing, and papermaking.

[0003] However, since the O-Si-O bond (164 pm) is longer than the C-C bond (154 pm), and the bond angle (142.5°) is much larger than the C-C bond angle (111°), the Si-O bond is more likely to rotate, generating a larger free volume, which results in a lower Tg value for organosilicon polymers. The glass transition temperature of polydimethylsiloxane is as low as -127°C, but its high chain regularity gives it a high crystallinity at -54°C, resulting in a brittle temperature of polydimethylsiloxane higher than the glass transition temperature, which will affect its performance at low temperatures.

[0004] In addition, most of the organosilicon polyurethanes prepared with polydimethylsiloxane alone as the soft segment have a tensile strength less than 10 MPa at room temperature and are easily damaged. Therefore, the key problem faced in preparing organosilicon polyurethane resin materials is how to reduce the influence of chain segment crystallization, improve the low-temperature resistance of organosilicon polyurethane resin materials, and at the same time improve their mechanical properties. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a high-strength and low-temperature-resistant organosilicon polyurethane resin and a preparation method thereof. The organosilicon polyurethane resin prepared by the present invention has both good low-temperature performance and mechanical properties.

[0006] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of a high-strength and low-temperature-resistant organosilicon polyurethane resin, comprising the following steps:

[0008] Mix a dihydroxypolysiloxane, a diisocyanate, an organic solvent and a catalyst, and carry out a prepolymerization reaction to obtain a polyurethane prepolymer;

[0009] Dilute the polyurethane prepolymer with an organic solvent, mix the diluted polyurethane prepolymer with an aromatic diamine chain extender, and carry out a first chain extension reaction to obtain a first chain extension product;

[0010] Mix the first chain extension product with a hydrazide chain extender to carry out a second chain extension reaction to obtain a second chain extension product;

[0011] Mix the second chain extension product with a crosslinker solution and carry out thermal curing and molding to obtain a high-strength low-temperature resistant organosilicon polyurethane resin.

[0012] Preferably, the dihydroxy polysiloxane preferably includes polydimethylsiloxane terminated with dihydroxy groups and / or poly(dimethylsiloxane-co-diphenylsiloxane) terminated with dihydroxy groups; the number average molecular weight of the dihydroxy polysiloxane is 1000 to 7000;

[0013] The diisocyanate includes one or more of hexamethylene diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, p-phenylene diisocyanate, and isophorone diisocyanate;

[0014] The catalyst includes an organotin catalyst.

[0015] Preferably, the molar ratio of the dihydroxy polysiloxane to the diisocyanate is 1:1 to 3;

[0016] The temperature of the prepolymerization reaction is 50 to 80 °C, and the time is 1 to 4 h.

[0017] Preferably, the aromatic diamine chain extender includes one or more of 4,4-diaminodiphenylmethane, 4,4-diaminostilbene, 4,4-diaminodiphenylamine, and 4,4-diaminodiphenyl ether;

[0018] The molar ratio of the aromatic diamine chain extender to the dihydroxy polysiloxane is 0 to 1.5:1, and the amount of the aromatic diamine chain extender is not 0.

[0019] Preferably, the temperature of the first chain extension reaction is 30 to 60 °C, and the time is 1 to 4 h.

[0020] Preferably, the hydrazide chain extender includes isophthaloyl hydrazide and / or terephthaloyl hydrazide;

[0021] The molar ratio of the hydrazide chain extender to the dihydroxy polysiloxane is 0 to 1.5:1, and the amount of the hydrazide chain extender is not 0.

[0022] Preferably, the temperature of the second chain extension reaction is 40 to 60 °C, and the time is 1 to 3 h.

[0023] Preferably, the crosslinker is hexamethylene diisocyanate trimer and / or triphenylmethane triisocyanate;

[0024] The molar ratio of the crosslinker to the dihydroxy polysiloxane is 0 to 0.5:1, and the amount of the crosslinker is not 0.

[0025] Preferably, the temperature for thermosetting molding is 60 - 90 °C and the time is 24 - 72 h.

[0026] The present invention provides a high-strength and low-temperature-resistant organosilicon polyurethane resin prepared by the above preparation method.

[0027] The present invention provides a preparation method of a high-strength and low-temperature-resistant organosilicon polyurethane resin, comprising the following steps: mixing a dihydroxy polysiloxane, a diisocyanate, an organic solvent and a catalyst, and carrying out a prepolymerization reaction to obtain a polyurethane prepolymer; diluting the polyurethane prepolymer with an organic solvent, mixing the diluted polyurethane prepolymer with an aromatic diamine chain extender, and carrying out a first chain extension reaction to obtain a first chain extension product; mixing the first chain extension product with a hydrazide chain extender, and carrying out a second chain extension reaction to obtain a second chain extension product; mixing the second chain extension product with a crosslinking agent solution, and carrying out thermosetting molding to obtain a high-strength and low-temperature-resistant organosilicon polyurethane resin. The organosilicon polyurethane resin provided by the present invention uses a dihydroxy polysiloxane and a diisocyanate as the base materials, introduces an aryl chain extender, and reduces the influence of low-temperature crystallization of the polymer by using a hard and soft segment alternating structure. Specifically, polydimethylsiloxane is the soft segment, and the reaction product of the diisocyanate and the chain extender is the hard segment. The alternating structure of the hard and soft segments of the polymer can reduce the crystallization of the polydimethylsiloxane chain segments, thereby improving its low-temperature performance and enabling it to exhibit very good flexibility at extremely low temperatures. In addition, a mismatched supramolecular structure can be formed between the aromatic chain extender and the hydrazide chain extender molecules, enhancing the intra- / inter-molecular forces, thereby improving the strength and toughness of the elastomer, and finally obtaining a high-performance polyurethane resin with high strength, high toughness and low-temperature resistance, so as to improve the reliability and durability of the low-temperature-resistant polyurethane protective material.

[0028] The preparation method provided by the present invention is simple to operate, low in cost, easy to realize industrial production, and the obtained organosilicon polyurethane resin has high strength, good low-temperature mechanical properties, low-temperature resilience performance, and is also characterized by easy film formation. Description of the Drawings

[0029] Figure 1 It is the normal temperature stress-strain curve of the organosilicon-modified polyurethane resin in Example 1;

[0030] Figure 2 It is the stress-strain curve of the organosilicon-modified polyurethane resin at -70 °C in Example 1. Detailed Embodiments

[0031] The present invention provides a preparation method of a high-strength and low-temperature-resistant organosilicon polyurethane resin, comprising the following steps:

[0032] Mix a dihydroxy polysiloxane, a diisocyanate, an organic solvent and a catalyst, and carry out a prepolymerization reaction to obtain a polyurethane prepolymer;

[0033] The polyurethane prepolymer is diluted with an organic solvent, and the diluted polyurethane prepolymer is mixed with an aromatic diamine chain extender to carry out a first chain extension reaction to obtain a first chain extension product;

[0034] The first chain extension product is mixed with a hydrazide chain extender to carry out a second chain extension reaction to obtain a second chain extension product;

[0035] The second chain extension product is mixed with a crosslinking agent solution and subjected to thermal curing molding to obtain a high-strength low-temperature resistant organosilicon polyurethane resin.

[0036] Unless otherwise specified, the raw materials used in the present invention are all commercially available.

[0037] In the present invention, a dihydroxy polysiloxane, a diisocyanate, an organic solvent and a catalyst are mixed to carry out a prepolymerization reaction to obtain a polyurethane prepolymer. In the present invention, the dihydroxy polysiloxane preferably includes polydimethylsiloxane terminated with dihydroxy and / or poly(dimethylsiloxane-co-diphenylsiloxane) terminated with dihydroxy, and more preferably polydimethylsiloxane terminated with dihydroxy. In the present invention, the molecular weight of the dihydroxy polysiloxane is preferably 1000-7000, and more preferably 3000-5000.

[0038] In the present invention, the diisocyanate preferably includes one or more of hexamethylene diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, p-phenylene diisocyanate and isophorone diisocyanate, and more preferably hexamethylene diisocyanate.

[0039] In the present invention, the catalyst preferably includes an organotin catalyst, and further preferably dibutyltin dibutyrate, dibutyltin dilaurate, dimethyltin dibutyrate, and more preferably dibutyltin dilaurate.

[0040] In the present invention, the molar ratio of the dihydroxy polysiloxane to the diisocyanate is preferably 1:1-3, and specifically may be 1:1, 1:2 or 1:3. In the present invention, the molar ratio of the dihydroxy polysiloxane to the catalyst is preferably 1:0.01-0.03, and more preferably 1:0.02.

[0041] In the present invention, the organic solvent is preferably one or more of N,N-dimethylformamide, dichloromethane and toluene, and more preferably toluene. In the present invention, the mass ratio of the dihydroxy polysiloxane to the organic solvent is preferably 1:0-1, and the amount of the organic solvent is not 0.

[0042] The present invention has no special requirements for the mixing method, and the well-known mixing methods in the art can be used, such as stirring and mixing. In the present invention, the temperature of the prepolymerization reaction is 50-80 °C, specifically 50, 60, 70 or 80 °C; the time of the prepolymerization reaction is preferably 1-4 h, specifically 1 h, 2 h, 3 h or 4 h. After the prepolymerization reaction, the present invention preferably does not perform post-treatment on the obtained polyurethane prepolymer and directly proceeds to the next reaction.

[0043] After obtaining the polyurethane prepolymer, the present invention dilutes the polyurethane prepolymer with an organic solvent, mixes the diluted polyurethane prepolymer with an aromatic diamine chain extender, and performs a first chain extension reaction to obtain a first chain extension product. In the present invention, the organic solvent preferably includes N,N-dimethylformamide and / or N,N-dimethylacetamide, more preferably N,N-dimethylformamide. In the present invention, the mass ratio of the polyurethane prepolymer to the organic solvent is preferably 1:0-1, and the amount of the organic solvent is not 0.

[0044] In the present invention, the aromatic diamine chain extender preferably includes one or more of 4,4-diaminodiphenylmethane, 4,4-diaminostilbene, 4,4-diaminodiphenylamine and 4,4-diaminodiphenyl ether, more preferably 4,4-diaminodiphenylmethane. In the present invention, the molar ratio of the aromatic diamine chain extender to the dihydroxypolysiloxane is preferably 0-1.5:1, and the amount of the aromatic diamine chain extender is not 0; in the present invention, the molar ratio of the aromatic diamine chain extender to the dihydroxypolysiloxane is more preferably 0.5-1.5:1, and further preferably 0.8-1.3:1.

[0045] In the present invention, the temperature of the first chain extension reaction is preferably 30-60 °C, specifically 30, 40, 50 or 60 °C, and the time is preferably 1-4 h, specifically 1 h, 2 h, 3 h or 4 h. In the present invention, in the first chain extension reaction, the role of the aryl chain extender is to increase the molecular weight of the polymer.

[0046] After the first chain extension reaction, the present invention preferably does not perform post-treatment on the obtained first chain extension product and directly proceeds to the next reaction.

[0047] After obtaining the first chain extension product, the present invention mixes the first chain extension product with a hydrazide chain extender and performs a second chain extension reaction to obtain a second chain extension product. In the present invention, the hydrazide chain extender preferably includes isophthaloyl hydrazide and / or terephthaloyl hydrazide, more preferably isophthaloyl hydrazide. In the present invention, the role of the hydrazide chain extender is to increase the molecular weight of the polymer and form a mismatched structure with the aryl chain extender.

[0048] In the present invention, the molar ratio of the hydrazide chain extender to the dihydroxypolysiloxane is preferably 0 to 1.5:1, and the amount of the hydrazide chain extender is not 0; in the present invention, the molar ratio of the hydrazide chain extender to the dihydroxypolysiloxane is more preferably 0.5 to 1.5:1, and further preferably 0.8 to 1.3:1.

[0049] In the present invention, the mixing method is preferably as follows: first, dissolve the hydrazide chain extender in an organic solvent, and then add the hydrazide chain extender solution to the first chain-extended product.

[0050] In the present invention, the temperature of the second chain extension reaction is preferably 40 to 60 °C, and specifically can be 40 °C, 50 °C or 60 °C; the time of the second chain extension reaction is preferably 1 to 3 h, and specifically can be 1 h, 2 h or 3 h.

[0051] After the second chain extension reaction, the present invention preferably does not perform post-treatment on the obtained second chain-extended product and directly proceeds to the next reaction.

[0052] After obtaining the second chain-extended product, the present invention mixes the second chain-extended product with a crosslinking agent solution and performs thermal curing molding to obtain a high-strength low-temperature-resistant organosilicon polyurethane resin. In the present invention, the crosslinking agent preferably includes hexamethylene diisocyanate trimer and / or triphenylmethane triisocyanate. In the present invention, the solvent of the crosslinking agent solution is preferably one or more of ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane and toluene, and the concentration of the crosslinking agent solution is preferably 0.1 to 0.3 g / mL.

[0053] In the present invention, the molar ratio of the crosslinking agent to the dihydroxypolysiloxane is preferably 0 to 0.5:1, and the amount of the crosslinking agent is not 0. As a specific embodiment of the present invention, the molar ratio of the crosslinking agent to the dihydroxypolysiloxane can be 0.1:1, 0.2:1, 0.3:1, 0.4:1 or 0.5:1.

[0054] The present invention preferably performs the thermal curing molding in a mold. In the present invention, the temperature of the thermal curing molding is preferably 60 to 90 °C, and specifically can be 60, 70, 80 or 90 °C; the time of the thermal curing molding is preferably 24 to 72 h, and more preferably 48 to 60 h.

[0055] The present invention provides a high-strength low-temperature-resistant organosilicon polyurethane resin prepared by the above preparation method.

[0056] The following examples are used to illustrate in detail the high-strength low-temperature-resistant organosilicon polyurethane resin and its preparation method provided by the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1

[0058] Preparation method of high-strength low-temperature resistant organosilicon polyurethane resin, comprising the following steps:

[0059] 1. Add 10 g of dihydroxypolydimethylsiloxane with a number average molecular weight of 2000, 2.22 g of isophorone diisocyanate, and 5 mL of dichloromethane into a three-necked flask, then add 0.06 g of dibutyltin dilaurate, heat up to 80 °C, and react for 3 hours to obtain a polyurethane prepolymer. Among them, the molar ratio of dihydroxypolydimethylsiloxane to isophorone diisocyanate is 1:2.

[0060] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 0.64 g of 4,4-diaminodiphenylmethane, and react at 40 °C for 1 hour to obtain a first chain extension product. Then dissolve 0.63 g of isophthaloyl hydrazide in 20 mL of toluene, add it to the first chain extension product, and react at 40 °C for 1 hour to obtain a second chain extension product. Among them, the molar ratio of dihydroxypolydimethylsiloxane, 4,4-diaminodiphenylmethane, and isophthaloyl hydrazide is 1:0.6:0.6.

[0061] 3. Dissolve 0.5 g of hexamethylene diisocyanate trimer in 5 mL of ethyl acetate solvent, add it to the second chain extension product, stir evenly, add it into a mold, and cure and form at 80 °C for 48 hours to obtain an organosilicon polyurethane resin.

[0062] Example 2

[0063] 1. The same as step 1 in Example 1.

[0064] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 0.68 g of 4,4-ethylenedianiline, and react at 40 °C for 1 hour to obtain a first chain extension product. Then dissolve 0.63 g of isophthaloyl hydrazide in 20 mL of toluene, add it to the first chain extension product, and react at 40 °C for 1 hour to obtain a second chain extension product. Among them, the molar ratio of dihydroxypolydimethylsiloxane, 4,4-ethylenedianiline, and isophthaloyl hydrazide is 1:0.6:0.6.

[0065] 3. The same as step 3 in Example 1.

[0066] Example 3

[0067] 1. Add 10 g of dihydroxypolydimethylsiloxane with a number-average molecular weight of 2000, 1.86 g of hexamethylene diisocyanate, and 5 mL of dichloromethane to a three-necked flask. Subsequently, add 25 mg of dibutyltin dilaurate, heat up to 80 °C, and react for 3 hours to obtain a polyurethane prepolymer. Among them, the molar ratio of dihydroxypolydimethylsiloxane to hexamethylene diisocyanate is 1:2.

[0068] 2. Keep consistent with step 2 in Example 1.

[0069] 3. Keep consistent with step 3 in Example 1.

[0070] Example 4

[0071] 1. Add 10 g of dihydroxypolydimethylsiloxane with a number-average molecular weight of 2000, 1.86 g of hexamethylene diisocyanate, and 5 mL of dichloromethane to a three-necked flask. Subsequently, add 25 mg of dibutyltin dilaurate, heat up to 80 °C, and react for 3 hours to obtain a polyurethane prepolymer. Among them, the molar ratio of dihydroxypolydimethylsiloxane to hexamethylene diisocyanate is 1:2.

[0072] 2. Keep consistent with step 2 in Example 2.

[0073] 3. Keep consistent with step 3 in Example 2.

[0074] Comparative Example 1

[0075] 1. Keep consistent with step 1 in Example 1.

[0076] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 0.64 g of 4,4-diaminodiphenylmethane, and react at 40 °C for 1 hour. Among them, the molar ratio of dihydroxypolydimethylsiloxane to 4,4-diaminodiphenylmethane is 1:1.

[0077] 3. Add the reaction product to a mold, heat at 80 °C for 48 hours to cure and form, and obtain the silicone polyurethane resin.

[0078] Comparative Example 2

[0079] 1. Keep consistent with step 1 in Example 1.

[0080] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 0.64 g of 4,4-diaminodiphenylmethane, and react at 40 °C for 1 hour. The molar ratio of dihydroxypolydimethylsiloxane to 4,4-diaminodiphenylmethane is 1:1.2.

[0081] 3. Dissolve 0.5 g of hexamethylene diisocyanate trimer in 5 mL of ethyl acetate solvent, add it to the above product, stir evenly, add the reaction product into a mold, and cure and form it by heating at 80 °C for 48 hours to obtain the silicone polyurethane resin.

[0082] Comparative Example 3

[0083] 1. Keep the same as step 1 in Example 3.

[0084] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 0.64 g of 4,4-diaminodiphenylmethane, and react at 40 °C for 1 hour. The molar ratio of dihydroxypolydimethylsiloxane to 4,4-diaminodiphenylmethane is 1:1.2.

[0085] 3. Dissolve 0.5 g of hexamethylene diisocyanate trimer in 5 mL of ethyl acetate solvent, add it to the above product, stir evenly, add the reaction product into a mold, and cure and form it by heating at 80 °C for 48 hours to obtain the silicone polyurethane resin.

[0086] Comparative Example 4

[0087] 1. Keep the same as step 1 in Example 1.

[0088] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 0.68 g of 4,4-diaminostilbene, and react at 40 °C for 1 hour. Among them, the molar ratio of dihydroxypolydimethylsiloxane to 4,4-diaminostilbene is 1:1.2.

[0089] 3. Dissolve 0.5 g of hexamethylene diisocyanate trimer in 5 mL of ethyl acetate solvent, add it to the above product, stir evenly, add the reaction product into a mold, and cure and form it by heating at 80 °C for 48 hours to obtain the silicone polyurethane resin.

[0090] Comparative Example 5

[0091] 1. Keep the same as step 1 in Example 3.

[0092] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 0.68 g of 4,4-diaminostilbene, and react at 40 °C for 1 hour. The molar ratio of dihydroxypolydimethylsiloxane to 4,4-diaminostilbene is 1:1.2.

[0093] 3. Dissolve 0.5 g of hexamethylene diisocyanate trimer crosslinker in 5 mL of ethyl acetate solvent, add it to the above product, stir evenly, add the reaction product into a mold, and cure and form it by heating at 80 °C for 48 hours to obtain the silicone polyurethane resin.

[0094] Comparative Example 6

[0095] 1. Be consistent with Step 1 in Example 1.

[0096] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 1.26 g of isophthalic dihydrazide, and react at 40 °C for 1 hour. The molar ratio of dihydroxy polydimethylsiloxane to isophthalic dihydrazide is 1:1.2.

[0097] 3. Dissolve 0.5 g of hexamethylene diisocyanate trimer in 5 mL of ethyl acetate solvent, add it to the above product, stir evenly, add the reaction product into a mold, and cure and form at 80 °C for 48 hours to obtain an organosilicon polyurethane resin.

[0098] Comparative Example 7

[0099] 1. Be consistent with Step 1 in Example 3.

[0100] 2. Add 10 mL of N,N-dimethylformamide to dilute the above polyurethane prepolymer, add 1.26 g of isophthalic dihydrazide, and react at 40 °C for 1 hour. The molar ratio of dihydroxy polydimethylsiloxane to isophthalic dihydrazide is 1:1.2.

[0101] 3. Dissolve 0.5 g of hexamethylene diisocyanate trimer in 5 mL of ethyl acetate solvent, add it to the above product, stir evenly, add the reaction product into a mold, and cure and form at 80 °C for 48 hours to obtain an organosilicon polyurethane resin.

[0102] Performance Test

[0103] Test the room temperature mechanical properties, low temperature mechanical properties and low temperature retraction properties of the organosilicon polyurethane resins obtained in Examples 1-4 and Comparative Examples 1-7. The method is as follows:

[0104] Room temperature mechanical properties: The prepared material is sampled according to GB / T 1040-2006, the test speed is 50 mm / min, and the tensile strength and elongation at break are tested at 25 °C.

[0105] Low temperature mechanical properties: The prepared material is sampled according to GB / T 1040-2006, the test speed is 50 mm / min, and the tensile strength and elongation at break are tested at -70 °C.

[0106] Low temperature retraction properties: The prepared material is sampled according to GB / T 7758-2020, and the temperature corresponding to a 50% retraction (TR 50 ) is tested. The test environment is an ethanol solution.

[0107] The room-temperature mechanical properties and low-temperature mechanical properties of the organosilicon polyurethane resins obtained in Examples 1 to 4 and Comparative Examples 1 to 7 are shown in Table 1. Among them, the room-temperature stress-strain curve of the organosilicon-modified polyurethane resin in Example 1 is as shown in Figure 1 , and the stress-strain curve at -70 °C is as shown in Figure 2 .

[0108] Table 1 Room-temperature mechanical properties and low-temperature mechanical properties of the organosilicon polyurethane resins obtained in Examples 1 to 4 and Comparative Examples 1 to 7

[0109]

[0110] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, low-temperature-resistant organosilicon polyurethane resin, characterized in that: The following steps are involved: Mixing dihydroxy polysiloxane, diisocyanate, organic solvent and catalyst to carry out prepolymerization reaction to obtain polyurethane prepolymer; diluting the polyurethane prepolymer with an organic solvent, mixing the diluted polyurethane prepolymer with an aromatic diamine chain extender, performing a first chain extension reaction, and obtaining a first chain extension product; The first chain extension product is mixed with a hydrazide chain extender to perform a second chain extension reaction to obtain a second chain extension product; The second chain extension product is mixed with a cross-linking agent solution and subjected to thermal curing to obtain a high-strength and low-temperature-resistant organosilicon polyurethane resin.

2. The preparation method according to claim 1, characterized in that: The bishydroxy polysiloxane preferably comprises bishydroxy-terminated polydimethylsiloxane and / or bishydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane); the number average molecular weight of the bishydroxy polysiloxane is 1000 to 7000; The diisocyanate includes one or more of hexamethylene diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, p-phenylene diisocyanate and isophorone diisocyanate; The catalyst includes an organotin catalyst.

3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the dihydroxy polysiloxane to the diisocyanate is 1:1 to 3; The prepolymerization reaction is carried out at a temperature of 50 to 80° C. and for a time of 1 to 4 hours.

4. The preparation method according to claim 1, characterized in that: The aromatic diamine chain extender includes one or more of 4,4-diaminodiphenylmethane, 4,4-diaminostilbene, 4,4-diaminodiphenylamine and 4,4-diaminodiphenyl ether; The molar ratio of the aromatic diamine chain extender to the dihydroxy polysiloxane is 0-1.5:1, and the amount of the aromatic diamine chain extender is not zero.

5. The preparation method according to claim 1 or 4, characterized in that: The temperature of the first chain extension reaction is 30-60° C. and the time is 1-4 hours.

6. The preparation method according to claim 1, characterized in that: The hydrazide chain extender includes isophthalic acid hydrazide and / or terephthalic acid hydrazide; The molar ratio of the hydrazide chain extender to the dihydroxy polysiloxane is 0-1.5:1, and the amount of the hydrazide chain extender is not zero.

7. The preparation method according to claim 1 or 6, characterized in that: The temperature of the second chain extension reaction is 40-60° C. and the time is 1-3 hours.

8. The preparation method according to claim 1, characterized in that: The cross-linking agent is hexamethylene diisocyanate trimer and / or triphenylmethane triisocyanate; The molar ratio of the cross-linking agent to the dihydroxy polysiloxane is 0 to 0.5:1, and the amount of the cross-linking agent is not zero.

9. The preparation method according to claim 1 or 8, characterized in that: The temperature of the thermal curing molding is 60 to 90° C. and the time is 24 to 72 hours.

10. The high-strength, low-temperature-resistant organosilicon polyurethane resin prepared by the preparation method according to any one of claims 1 to 9.

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