A novel three-component blended polyurea thermoplastic elastomer and its preparation method

Abstract

The present invention provides a novel three-component blended polyurea thermoplastic elastomer and a preparation method thereof, belonging to the field of polyurea thermoplastic elastomers. The novel three-component blended polyurea thermoplastic elastomer of the present invention is formed by mixing 20 to 70 parts of polysiloxane-polyurea, 30 to 80 parts of polyether-polyurea, and 3 to 20 parts of a polymer having polysiloxane-polyurea and polyether-polyurea structures, wherein the hard segment content in the polysiloxane-polyurea and polyether-polyurea is independently 15 to 50 wt%, and the R value is independently 0.98 to 1.02. The present invention first prepares a polymer having polysiloxane-polyurea and polyether-polyurea structures and uses it as a compatibilizer, and then prepares the novel three-component blended polyurea thermoplastic elastomer, so that the obtained elastomer simultaneously has the excellent properties of polysiloxane such as weather resistance, water repellency, temperature resistance and flexibility, as well as the high strength and high modulus of polyurea, and has excellent comprehensive performance.

Description

Technical Field

[0001] The present invention relates to the field of polyurea thermoplastic elastomers, and particularly to a novel three-component blended polyurea thermoplastic elastomer and a preparation method thereof. Background Art

[0002] Polyurea thermoplastic elastomers are block polymers formed by the reaction of isocyanate compounds with amino compounds, consisting of two parts: hard segments and soft segments. The properties of the elastomers can be regulated by adjusting the molecular structures and ratios of the soft and hard segments. Polysiloxane is a typical flexible chain segment and can be used as the soft segment component of polyurea elastomers to improve certain properties of traditional polyurea, such as hydrophobicity, weather resistance, and low-temperature resistance. Therefore, polysiloxane-modified polyurea thermoplastic elastomers have always been a research hotspot.

[0003] Currently, there are two methods to introduce polysiloxane into polyurea. One is to use polysiloxane alone as the soft chain segment, and the polyurea prepared therefrom is named polysiloxane-polyurea by us; the other is to mix polysiloxane with traditional end-amine polyethers and use them as the soft chain segment, and the polyurea prepared therefrom is named polysiloxane-modified polyurea by us.

[0004] Patent CN102428117B reports that polyether-polyurea synthesized by using amine-terminated polyether, polyether diol with a molecular weight less than 500 g / mol and diisocyanate has a tensile strength of up to 27 MPa. However, when polysiloxane completely replaces polyether as a soft segment, or introduces part of polysiloxane and polyether as a soft segment, the obtained polyurea has a lower strength than that of polyether alone as a soft segment. Natascha et al. used terminal aminopropyl polysiloxane with a molecular weight of 3000-9000 g / mol, 1,3-bis(aminopropyl)-tetramethyldisiloxane, and dicyclohexylmethane diisocyanate as raw materials, and synthesized polysiloxane-polyurea by a two-step method. The polysiloxane-polyurea has good physiological inertness and hydrophobicity, but the 100% modulus of this polysiloxane-polyurea is only 0.2-2 MPa, and the tensile strength is only 1-6 MPa (Reference: Natascha Riehle, et al. European Polymer Journal, 2018, 101, 190-201.), and the mechanical properties are relatively poor. Patent CN112980302B discloses a polysiloxane-polyurea synthesized by a traditional method, that is, a polyurea synthesized from raw materials such as terminal amino polysiloxane with a molecular weight of 500 to 10,000 g / mol, isophorone diisocyanate, triaminobenzene, etc., with a tensile strength of 0.02 to 2.5 MPa. Although the good hydrophobicity of polysiloxane is retained, the material strength is very low. Patent CN1764684 discloses a linear polyurea prepared from three raw materials, amino polysiloxane, a series of aliphatic diisocyanates, and polyether polyols, and its maximum strength does not exceed 7 MPa. Patent CN112794975A ​​uses terminal hydroxyl polysiloxane and amino polyether as soft segments, small molecule polyols as chain extenders, and silane coupling agents as crosslinking agents to prepare polysiloxane-modified polyurethane urea, which overcomes the defects of low strength of polysiloxane and poor weather resistance of polyether to a certain extent, and the tensile strength reaches 22 MPa. However, compared with traditional polyether-polyurea, its strength is still insufficient, and due to the introduction of silane coupling agent for chemical cross-linking, the material does not have thermoplasticity and cannot be processed secondary.

[0005] In summary, there are currently two technical routes for silicone-modified polyurea: one is to use hydroxyl or amino polysiloxane alone as a soft segment, and the other is to mix polysiloxane with polyether as a soft segment. The preparation technology still follows the traditional preparation technology of polyurea thermoplastic elastomers.

[0006] Therefore, it is of great significance to develop a new three-component blended polyurea thermoplastic elastomer and a preparation method thereof to obtain a polyurea thermoplastic elastomer with excellent mechanical properties, high temperature resistance and hydrophobicity. Summary of the invention

[0007] The object of the present invention is to provide a novel three-component blended polyurea thermoplastic elastomer and a preparation method thereof, so as to solve the technical problem of poor comprehensive performance of polyurea thermoplastic elastomers in the prior art.

[0008] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a novel three-component blended polyurea thermoplastic elastomer, which is formed by mixing 20-70 parts of polysiloxane-polyurea, 30-80 parts of polyether-polyurea and 3-20 parts of a polymer having polysiloxane-polyurea and polyether-polyurea structures, wherein the hard segment content in the polysiloxane-polyurea and polyether-polyurea is independently 15-50 wt%, and the R value is independently 0.98-1.02.

[0010] Preferably, the polysiloxane-polyurea has the general formula shown in formula (I):

[0011]

[0012] The polyether-polyurea has the general formula shown in formula (II):

[0013]

[0014] Wherein, n and r are independently selected from integers of 15-65; m and m' are independently selected from integers of 50-100; X is independently selected from one of cyclohexylmethane diisocyanate segments, diphenylmethane diisocyanate segments, hexamethylene diisocyanate segments and toluene diisocyanate segments; Y is independently selected from one of (CH2)4, (CH2)5, (CH2)6, CH2CH2CH3 and CH2CH2CH2.

[0015] Preferably, the polymer having polysiloxane-polyurea and polyether-polyurea structures is selected from one of the general formulas shown in formula (III), (IV), (V), (VI):

[0016]

[0017]

[0018] Wherein, q is independently taken as an integer greater than 1 and less than or equal to 4; p and s are independently taken as integers of 2-4; o is independently selected from 50-100.

[0019] The present invention provides a preparation method of a novel three-component blended polyurea thermoplastic elastomer, comprising the following steps:

[0020] (1) A diisocyanate compound and an aminopropyl-terminated polysiloxane are mixed in a solvent for reaction. After adding compound N to the reaction product, the reaction is continued to obtain Polymer-1;

[0021] (2) A diisocyanate compound and an amino-terminated polyether are mixed in a solvent for reaction. After adding compound N to the reaction product, the reaction is continued to obtain Polymer-2;

[0022] The compound N is independently selected from one or more of chain extender E, capping agent F, chain extender G, chain extender H, and chain extender I;

[0023] (3) Polymer-1, Polymer-2, and a catalyst are mixed and then reacted to obtain a polymer having a polysiloxane-polyurea and a polyether-polyurea structure;

[0024] (4) The polysiloxane-polyurea, polyether-polyurea, and the polymer having a polysiloxane-polyurea and a polyether-polyurea structure are mixed in a solvent and then subjected to a drying treatment to obtain a novel three-component blended polyurea thermoplastic elastomer.

[0025] Preferably, in steps (1), (2), and (4), the solvent independently comprises one or more of N,N-dimethylformamide, acetone, tetrahydrofuran, isopropanol, n-hexane, toluene, and cyclohexane.

[0026] Preferably, in steps (1) and (2), the diisocyanate compound independently comprises one or more of dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate;

[0027] The aminopropyl-terminated polysiloxane has a general formula shown in formula (Ⅶ):

[0028]

[0029] Among them, n is an integer selected from 15 to 65;

[0030] The amino-terminated polyether has a general formula shown in formula (Ⅷ):

[0031]

[0032] Among them, r is an integer selected from 15 to 65.

[0033] Preferably, the chain extender E is selected from one or more of NH2(CH2)4NH2, NH2(CH2)5NH2, NH2(CH2)6NH2, and NH2CH2CH(CH3)CH2CH2CH2NH2; the end-capping agent F is selected from one or more of CH3(CH2)2NH2, CH3(CH2)3NH2, CH3(CH2)4NH2, and CH3(CH2)5NH2; the chain extender G has the general formula shown in formula (Ⅸ):

[0034]

[0035] wherein, p independently takes an integer from 2 to 4;

[0036] The chain extender H has the general formula shown in formula (Ⅹ):

[0037]

[0038] wherein, q independently takes an integer greater than 1 and less than or equal to 4;

[0039] The chain extender I has the general formula shown in formula (Ⅺ):

[0040]

[0041] wherein, s independently takes an integer from 2 to 4.

[0042] Preferably, in the step (1), the mass ratio of the diisocyanate compound, the amino-terminated polysiloxane, the solvent, and the compound N is 3 - 26: 6 - 70: 70 - 400: 0.5 - 9.

[0043] Preferably, in the step (2), the mass ratio of the diisocyanate compound, the amino-terminated polyether, the solvent, and the compound N is 5 - 65: 22 - 165: 120 - 1000: 0.5 - 20; in the step (3), the molar ratio of the polymer - 1 and the polymer - 2 is 1: 1.5 - 5.0.

[0044] Preferably, in the steps (1) and (2), the reaction temperature is independently 20 - 30 °C, and the reaction time is independently 10 - 30 min; in the step (3), the reaction temperature is 50 - 110 °C, and the reaction time is 8 - 24 h.

[0045] Advantages of the present invention:

[0046] (1) The present invention introduces a preparation method of a polymer blend system to obtain a novel three-component blended polyurea thermoplastic elastomer.

[0047] (2) Different from the common melt blending method, the present invention adopts solution blending, which can be completed at room temperature without complex heating equipment. Based on the compatibilization of the compatibilizer, the blend has a thermodynamically stable structure, avoiding the defects of melt blending.

[0048] (3) The novel three-component blended polyurea thermoplastic elastomer prepared by the present invention simultaneously has the excellent properties of polysiloxane such as weather resistance, water repellency, temperature resistance and flexibility, as well as high strength and high modulus of polyurea, and has excellent comprehensive properties. Detailed implementation manners

[0049] Term description:

[0050] Polysiloxane-polyurea: Polyurea prepared by using amino polysiloxane alone as the soft segment.

[0051] Polyether-polyurea: Polyurea prepared by using amino polyether alone as the soft segment.

[0052] R value: The R value of polyurea is a commonly used parameter in the art, that is, the molar ratio of NCO groups to amino groups in the system.

[0053] Hard segment content: It refers to the mass percentage of isocyanate compounds, chain extenders and end-capping agents in the material.

[0054] In the examples, the preparation methods of the polysiloxane-polyurea and polyether-polyurea are prepolymerization and chain extension methods, which are publicly known methods in the art.

[0055] The present invention provides a novel three-component blended polyurea thermoplastic elastomer, which is composed of 20-70 parts of polysiloxane-polyurea, 30-80 parts of polyether-polyurea and 3-20 parts of a polymer having polysiloxane-polyurea and polyether-polyurea structures, wherein the hard segment contents in the polysiloxane-polyurea and polyether-polyurea are independently 15-50 wt%, and the R values are independently 0.98-1.02.

[0056] In the present invention, the mass fraction of the polysiloxane-polyurea is preferably 25-65 parts, more preferably 30-60 parts; the mass fraction of the polyether-polyurea is preferably 35-75 parts, more preferably 40-70 parts; the mass fraction of the polymer having polysiloxane-polyurea and polyether-polyurea structures is preferably 5-18 parts, more preferably 7-16 parts; the hard segment contents in the polysiloxane-polyurea and polyether-polyurea are independently preferably 20-45 wt%, more preferably 25-40 wt%; the R values are independently preferably 0.99-1.01.

[0057] In the present invention, the polysiloxane-polyurea has the general formula shown in formula (Ⅰ):

[0058]

[0059] The polyether-polyurea has a general formula shown in formula (II):

[0060]

[0061] Wherein, n and r are independently selected from integers of 15 to 65, preferably 20 to 60, and more preferably 25 to 55; m and m' are independently selected from integers of 50 to 100, preferably 55 to 95, and more preferably 60 to 90; X is independently selected from one of a dicyclohexylmethane diisocyanate segment, a diphenylmethane diisocyanate segment, a hexamethylene diisocyanate segment, and a toluene diisocyanate segment, preferably one of a dicyclohexylmethane diisocyanate segment, a diphenylmethane diisocyanate segment, and a toluene diisocyanate segment; Y is independently selected from one of (CH2)4, (CH2)5, (CH2)6, CH2CH2CH3, and CH2CH2CH2, preferably one of (CH2)4, CH2CH2CH3, and CH2CH2CH2.

[0062] In the present invention, the polymers having a polysiloxane-polyurea and a polyether-polyurea structure are selected from one of the general formulas shown in formula (III), (IV), (V), and (VI):

[0063]

[0064] Wherein, q is independently taken from integers greater than 1 and less than or equal to 4, preferably 2 or 3; p and s are independently taken from integers of 2 to 4, preferably 3 or 4; o is independently selected from integers of 50 to 100, preferably 55 to 95, and more preferably 60 to 90.

[0065] The present invention provides a preparation method of a novel three-component blended polyurea thermoplastic elastomer, comprising the following steps:

[0066] (1) Mix a diisocyanate compound and an amine-terminated polyorganosiloxane in a solvent for reaction, and continue the reaction after adding compound N to the reaction product to obtain polymer-1;

[0067] (2) Mix a diisocyanate compound and an amine-terminated polyether in a solvent for reaction, and continue the reaction after adding compound N to the reaction product to obtain polymer-2;

[0068] The compound N is independently selected from one or more of a chain extender E, a capping agent F, a chain extender G, a chain extender H, and a chain extender I;

[0069] (3) Mix polymer-1, polymer-2, and a catalyst and carry out a reaction to obtain a polymer having a polysiloxane-polyurea and a polyether-polyurea structure;

[0070] (4) Mix polysiloxane-polyurea, polyether-polyurea, and polymers with polysiloxane-polyurea and polyether-polyurea structures in a solvent, and then perform a drying treatment to obtain a novel three-component blended polyurea thermoplastic elastomer.

[0071] In the present invention, in the steps (1), (2), and (4), the solvent independently includes one or more of N,N-dimethylformamide, acetone, tetrahydrofuran, isopropanol, n-hexane, toluene, and cyclohexane, preferably a mixed solvent of toluene and acetone, a mixed solvent of n-hexane and acetone, a mixed solvent of n-hexane and tetrahydrofuran, a mixed solvent of cyclohexane and tetrahydrofuran, a mixed solvent of toluene and isopropanol, and a mixed solvent of cyclohexane and isopropanol.

[0072] In the present invention, in the steps (1) and (2), the diisocyanate compound independently includes one or more of dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate, preferably one or more of dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate, and more preferably dicyclohexylmethane diisocyanate;

[0073] The amino-terminated polysiloxane has a general formula shown in formula (Ⅶ):

[0074]

[0075] Among them, n is selected from integers of 15 to 65, preferably 20 to 60, and more preferably 25 to 55;

[0076] The amino-terminated polyether has a general formula shown in formula (Ⅷ):

[0077]

[0078] Among them, r is selected from integers of 15 to 65, preferably 20 to 60, and more preferably 25 to 55.

[0079] In the present invention, the chain extender E is selected from one or more of NH2(CH2)4NH2, NH2(CH2)5NH2, NH2(CH2)6NH2, and NH2CH2CH(CH3)CH2CH2CH2NH2, preferably one or more of NH2(CH2)4NH2, NH2(CH2)5NH2, and NH2(CH2)6NH2, and more preferably NH2(CH2)4NH2 and / or NH2(CH2)5NH2.

[0080] In the present invention, the capping agent F is selected from one or more of CH3(CH2)2NH2, CH3(CH2)3NH2, CH3(CH2)4NH2, and CH3(CH2)5NH2, preferably one or more of CH3(CH2)3NH2, CH3(CH2)4NH2, and CH3(CH2)5NH2, and more preferably CH3(CH2)3NH2 and / or CH3(CH2)5NH2; the chain extender G has the general formula shown in formula (Ⅸ):

[0081]

[0082] wherein, p independently takes an integer from 2 to 4, preferably 3 or 4;

[0083] In the present invention, the chain extender H has the general formula shown in formula (Ⅹ):

[0084]

[0085] wherein, q independently takes an integer greater than 1 and less than or equal to 4, preferably 2 or 3;

[0086] In the present invention, the chain extender I has the general formula shown in formula (Ⅺ):

[0087]

[0088] wherein, s independently takes an integer from 2 to 4, preferably 3 or 4.

[0089] In the present invention, in the step (1), the mass ratio of the diisocyanate compound, the amino-terminated polysiloxane, the solvent, and the compound N is 3 - 26:6 - 70:70 - 400:0.5 - 9, preferably 5 - 24:10 - 65:80 - 380:0.8 - 8, and more preferably 7 - 22:15 - 60:100 - 350:1 - 7.

[0090] In the present invention, in the step (2), the mass ratio of the diisocyanate compound, the amino-terminated polyether, the solvent, and the compound N is 5 - 65:22 - 165:120 - 1000:0.5 - 20, preferably 10 - 60:25 - 160:150 - 900:1 - 19, and more preferably 15 - 55:30 - 150:180 - 800:2 - 18.

[0091] In the present invention, in the step (3), when the polymer - 1 and the polymer - 2 are mixed for reaction, a catalyst is preferably added, and the catalyst is preferably stannous octoate or dibutyltin dilaurate, and the addition amount is 0.05 - 0.5% of the total mass of the system.

[0092] In the present invention, in the step (3), the molar ratio of Polymer-1 to Polymer-2 is 1:1.5 to 5.0. Preferably, when preparing the polymer having a polysiloxane-polyurea and polyether-polyurea structure of formula (III), the molar ratio of Polymer-1 to Polymer-2 is 1:2; when preparing the polymer having a polysiloxane-polyurea and polyether-polyurea structure of formula (IV), the molar ratio of Polymer-1 to Polymer-2 is 1:4; when preparing the polymer having a polysiloxane-polyurea and polyether-polyurea structure of formula (V) or (VI), the molar ratio of Polymer-1 to Polymer-2 is 1:1.5 to 5.0.

[0093] In the present invention, in the steps (1) and (2), the reaction temperature is independently 20 to 30 °C, preferably 25 °C; the reaction time is independently 10 to 30 min, preferably 15 to 25 min, and more preferably 20 min; in the step (3), the reaction temperature is 50 to 110 °C, preferably 60 to 100 °C, and more preferably 70 to 90 °C; the reaction time is 8 to 24 h, preferably 10 to 22 h, and more preferably 12 to 20 h.

[0094] In the present invention, in the step (4), the amount of the solvent used is 3 to 8 times the total mass of the system, preferably 4 to 7 times, and more preferably 5 times or 6 times.

[0095] The technical

[0096] solution provided by the present invention will be described in detail below with reference to the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0097] Example 1

[0098] The solvent used in Example 1 was a mixed solvent of toluene and acetone (mass ratio 4:1).

[0099] 10.3 g of dicyclohexylmethane diisocyanate and 40 g of the mixed solvent were added to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant pressure dropping funnel, and a drying tube. 39.4 g of Compound VII with a molecular weight of 3300 g / mol was dissolved in 160 g of the mixed solvent and slowly added dropwise using the constant pressure dropping funnel. After the addition was completed, stirring was continued for 20 min. 2.78 g of Compound NH2CH2CH(CH3)CH2CH2CH2NH2, 0.18 g of diethanolamine, and 0.15 g of pentylamine were mixed and dissolved in 12 g of the mixed solvent, and then added dropwise to the reaction system. The reaction was carried out at 25 °C for 20 min to obtain Polymer-1.

[0100] Add 27.2 g of dicyclohexylmethane diisocyanate and 108 g of a mixed solvent to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 99.3 g of the compound of Formula VIII with a molecular weight of 2000 g / mol in 400 g of the mixed solvent, and slowly add it dropwise using the constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 20 min. Dissolve 5.76 g of NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.19 g of pentylamine in 24 g of the mixed solvent, and slowly add it dropwise using the constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 20 min to obtain Polymer-2.

[0101] Mix Polymer-1 and Polymer-2 in a molar ratio of 1:2, then add 0.2 wt% stannous octoate, and heat to 100 °C and react for 20 h to obtain a polymer with a polysiloxane-polyurea and polyether-polyurea structure having the structure of Formula (Ⅲ).

[0102] Mix 40 parts of polysiloxane-polyurea (Ⅰ) with a hard segment content of 22 wt% (where the R value is 1.02), 60 parts of polyether-polyurea (Ⅱ) with a hard segment content of 25 wt% (where the R value is 1.02), and 15 parts of a polymer with a polysiloxane-polyurea and polyether-polyurea structure (Ⅲ) in 5 times the amount of the mixed solvent. After stirring evenly, pour it into a polytetrafluoroethylene mold, cure at room temperature, and dry at 50 °C for 24 h to obtain a novel three-component blended polyurea thermoplastic elastomer. In polysiloxane-polyurea (Ⅰ) and polyether-polyurea (Ⅱ), X is a dicyclohexylmethane diisocyanate chain segment, and Y is (CH2)4.

[0103] Performance test:

[0104] The tensile strength of the novel three-component blended polyurea thermoplastic elastomer is 15 MPa, the elongation at break is 380%, the 5% thermal weight loss temperature is 315 °C, the water contact angle is 108.3°, and it has two glass transition temperatures of -123 °C and -62 °C, showing good low-temperature resistance.

[0105] Example 2

[0106] The solvent used in Example 2 is a mixed solvent of n-hexane and acetone (mass ratio 2:1).

[0107] Add 5 g of dicyclohexylmethane diisocyanate and 25 g of a mixed solvent into a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 20.2 g of Compound VII with a molecular weight of 3300 g / mol in 100 g of the mixed solvent, and slowly add it dropwise using the constant-pressure dropping funnel. After the addition is complete, continue stirring for 15 min. Mix 1.4 g of Compound NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.07 g of diethanolamine and dissolve them in 7 g of the mixed solvent, and then add it dropwise to the reaction system. React at 25 °C for 15 min to obtain Polymer-1.

[0108] Add 10.9 g of dicyclohexylmethane diisocyanate and 55 g of a mixed solvent into a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 40.1 g of Compound VIII with a molecular weight of 2000 g / mol in 200 g of the mixed solvent, and slowly add it dropwise using the constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 15 min. Mix 2.3 g of NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.15 g of butylamine and dissolve them in 12 g of the mixed solvent, and slowly add it dropwise using the constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 15 min to obtain Polymer-2.

[0109] Mix Polymer-1 and Polymer-2 in a molar ratio of 1:4, then add 0.2 wt% stannous octoate, and heat to 65 °C and react for 24 h to obtain a polymer with a polysiloxane-polyurea and polyether-polyurea structure having the structure of formula (IV).

[0110] Mix 45 parts of polysiloxane-polyurea (I) with a hard segment content of 26 wt% (where the R value is 1.00), 55 parts of polyether-polyurea (II) with a hard segment content of 22 wt% (where the R value is 1.02), and 17 parts of a polymer with a polysiloxane-polyurea and polyether-polyurea structure (IV) in 5 times the amount of the mixed solvent. After stirring evenly, pour it into a polytetrafluoroethylene mold, cure at room temperature, and dry at 50 °C for 24 h to obtain a novel three-component blended polyurea thermoplastic elastomer. In polysiloxane-polyurea (I) and polyether-polyurea (II), X is a dicyclohexylmethane diisocyanate segment, and Y is CH2CH2CH3.

[0111] Performance test:

[0112] The tensile strength of the novel three-component blended polyurea thermoplastic elastomer is 20.31 MPa, the elongation at break is 780%, and the thermal weight loss temperature of 5% of the thermoplastic elastomer is 315 °C.

[0113] Example 3

[0114] The solvent used in Example 3 was a mixed solvent of n-hexane and tetrahydrofuran (mass ratio 3:1).

[0115] 3.08 g of diphenylmethane diisocyanate and 18 g of the mixed solvent were added to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. 7.74 g of Compound VII with a molecular weight of 3300 g / mol was dissolved in 46 g of the mixed solvent and slowly added dropwise using the constant-pressure dropping funnel. After the addition was complete, stirring was continued for 15 min. 0.82 g of Compound NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.16 g of 2-hydroxy-1,3-propanediamine were mixed and dissolved in 6 g of the mixed solvent, and then added dropwise to the reaction system. The reaction was carried out at 25 °C for 15 min to obtain Polymer-1.

[0116] 8.91 g of diphenylmethane diisocyanate and 54 g of the mixed solvent were added to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. 22.6 g of Compound VIII with a molecular weight of 2000 g / mol was dissolved in 132 g of the mixed solvent and slowly added dropwise using the constant-pressure dropping funnel. After the addition was complete, stirring was continued for 15 min. 2.58 g of NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.06 g of hexylamine were dissolved in 15 g of the mixed solvent and slowly added dropwise using the constant-pressure dropping funnel. After the addition was complete, stirring was continued for 15 min to obtain Polymer-2.

[0117] Polymer-1 and Polymer-2 were mixed in a molar ratio of 1:3, and then 0.2 wt% stannous octoate was added. The mixture was heated to 110 °C and reacted for 10 h to obtain a polymer with a polysiloxane-polyurea and polyether-polyurea structure having the structure of formula (V).

[0118] 30 parts of polysiloxane-polyurea (I) with a hard segment content of 37 wt% (where the R value is 0.99), 70 parts of polyether-polyurea (II) with a hard segment content of 33 wt% (where the R value is 1.02), and 13 parts of the polymer (V) having a polysiloxane-polyurea and polyether-polyurea structure were mixed in 6 times the amount of the mixed solvent. After stirring evenly, the mixture was poured into a polytetrafluoroethylene mold and cured at room temperature, and dried at 50 °C for 24 h to obtain a novel three-component blended polyurea thermoplastic elastomer. In the polysiloxane-polyurea (I) and polyether-polyurea (II), X is a diphenylmethane diisocyanate segment, and Y is (CH2)6.

[0119] Performance testing:

[0120] The tensile strength of the novel three-component blended polyurea thermoplastic elastomer is 24.69 MPa, the elongation at break is 486%, it has good hydrophobicity, the water contact angle is 110.4°, and the water absorption rate is 2.14% after soaking in water for 40 days at room temperature.

[0121] Example 4

[0122] The solvent used in Example 4 is a mixed solvent of cyclohexane and tetrahydrofuran (mass ratio 4:1).

[0123] Add 5.6 g of dicyclohexylmethane diisocyanate and 28 g of the mixed solvent to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 23.6 g of Compound VII with a molecular weight of 3300 g / mol in 115 g of the mixed solvent, and slowly add it dropwise using a constant-pressure dropping funnel. After the addition is complete, continue stirring for 15 min. Mix 1.25 g of Compound NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.31 g of 2-hydroxy-1,3-propanediamine and dissolve them in 6 g of the mixed solvent, then add them dropwise to the reaction system and react at 25 °C for 15 min to obtain Polymer-1.

[0124] Add 5.2 g of dicyclohexylmethane diisocyanate and 26 g of the mixed solvent to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 19.77 g of Compound VIII with a molecular weight of 2000 g / mol in 100 g of the mixed solvent, and slowly add it dropwise using a constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 15 min. Mix 1.1 g of NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.04 g of pentylamine and dissolve them in 6 g of the mixed solvent, then slowly add it dropwise using a constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 15 min to obtain Polymer-2.

[0125] Mix Polymer-1 and Polymer-2 in a molar ratio of 1:1, then add 0.2 wt% stannous octoate and heat to 80 °C and react for 16 h to obtain a polymer with a polysiloxane-polyurea and polyether-polyurea structure having the structure of formula (V).

[0126] 32 parts of polysiloxane-polyurea (Ⅰ) with a hard segment content of 25 wt% (where the R value is 1.01), 68 parts of polyether-polyurea (Ⅱ) with a hard segment content of 23 wt% (where the R value is 0.98), and 12 parts of a polymer (Ⅲ) having polysiloxane-polyurea and polyether-polyurea structures are mixed in 5 times the amount of a mixed solvent. After stirring evenly, it is poured into a polytetrafluoroethylene mold and cured at room temperature, and dried at 50 °C for 24 h to obtain a novel three-component blended polyurea thermoplastic elastomer. In polysiloxane-polyurea (Ⅰ) and polyether-polyurea (Ⅱ), X is a dicyclohexylmethane diisocyanate segment, and Y is (CH2)5.

[0127] Performance test:

[0128] The tensile strength of the novel three-component blended polyurea thermoplastic elastomer is 19.8 MPa, and the elongation at break is 806%.

[0129] Example 5

[0130] The solvent used in Example 5 is a mixed solvent of toluene and isopropanol (mass ratio 1:1).

[0131] Add 25.3 g of dicyclohexylmethane diisocyanate and 100 g of the mixed solvent to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 63.8 g of Compound Ⅶ with a molecular weight of 2970 g / mol in 256 g of the mixed solvent, and slowly add it dropwise using a constant-pressure dropping funnel. After the addition is complete, continue stirring for 15 min. Mix 6.5 g of Compound NH2CH2CH(CH3)CH2CH2CH2NH2 and 2.46 g of 3,3'-diaminodipropylamine and dissolve them in 36 g of the mixed solvent, and then add them dropwise to the reaction system and react at 25 °C for 15 min to obtain Polymer-1.

[0132] Add 64 g of dicyclohexylmethane diisocyanate and 256 g of the mixed solvent to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 162.2 g of Compound VIII with a molecular weight of 2000 g / mol in 648 g of the mixed solvent, and slowly add it dropwise using a constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 20 min. Mix 18.7 g of NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.36 g of pentylamine and dissolve them in 76 g of the mixed solvent, and slowly add it dropwise using a constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 15 min to obtain Polymer-2.

[0133] Mix Polymer-1 and Polymer-2 in a molar ratio of 1:2.5, then add 0.2 wt% stannous octoate, heat to 50 °C and react for 24 h to obtain a polymer with a polysiloxane-polyurea and polyether-polyurea structure having the structure of formula (VI).

[0134] Mix 40 parts of polysiloxane-polyurea (Ⅰ) with a hard segment content of 35 wt% (where the R value is 0.98), 60 parts of polyether-polyurea (Ⅱ) with a hard segment content of 35 wt% (where the R value is 0.98), and 20 parts of the polymer (VI) having a polysiloxane-polyurea and polyether-polyurea structure in 4 times the mixed solvent. After stirring evenly, pour it into a polytetrafluoroethylene mold, cure at room temperature, and dry at 50 °C for 24 h to obtain a novel three-component blended polyurea thermoplastic elastomer. Wherein X in polysiloxane-polyurea (Ⅰ) and polyether-polyurea (Ⅱ) is a dicyclohexylmethane diisocyanate segment, and Y is CH2CH2CH3.

[0135] Performance test:

[0136] The tensile strength of the novel three-component blended polyurea thermoplastic elastomer is 31.65 MPa, the elongation at break is 471%, and the water absorption rate after soaking in water at room temperature for 40 d is 1.27%.

[0137] Example 6

[0138] The solvent used in Example 6 is a mixed solvent of cyclohexane and isopropyl alcohol (mass ratio 2:1).

[0139] Add 4.55 g of diphenylmethane diisocyanate and 33 g of the mixed solvent to a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 30 g of Compound Ⅶ with a molecular weight of 3300 g / mol in 210 g of the mixed solvent, and slowly add it dropwise with a constant-pressure dropping funnel. After the addition is complete, continue stirring for 15 min. Mix 0.885 g of Compound NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.2 g of 2-hydroxy-1,3-propanediamine and dissolve them in 7 g of the mixed solvent, and then add them dropwise to the reaction system. React at 25 °C for 30 min to obtain Polymer-1.

[0140] Into a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube, add 5.4 g of diphenylmethane diisocyanate and 38 g of a mixed solvent. Dissolve 30 g of the compound of formula VIII with a molecular weight of 2000 g / mol in 210 g of the mixed solvent, and slowly add it dropwise using the constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 20 min. Dissolve 0.7 g of NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.05 g of pentylamine in 5 g of the mixed solvent, slowly add it dropwise using the constant-pressure dropping funnel, and continue stirring and reacting for 15 min after the addition is complete to obtain Polymer-2.

[0141] Mix Polymer-1 and Polymer-2 in a molar ratio of 1:2, then add 0.2 wt% stannous octoate, heat to 65 °C and react for 24 h to obtain a polymer with a polysiloxane-polyurea and polyether-polyurea structure having the structure of formula (IV).

[0142] Mix 50 parts of polysiloxane-polyurea (I) with a hard segment content of 16 wt% (where the R value is 0.99), 50 parts of polyether-polyurea (II) with a hard segment content of 16 wt% (where the R value is 1.02), and 8 parts of the polymer (V) having a polysiloxane-polyurea and polyether-polyurea structure in 7 times the amount of the mixed solvent. After stirring evenly, pour it into a polytetrafluoroethylene mold, cure at room temperature, and dry at 50 °C for 24 h to obtain a novel three-component blended polyurea thermoplastic elastomer. In the polysiloxane-polyurea (I) and polyether-polyurea (II), X is diphenylmethane diisocyanate and Y is (CH2)4.

[0143] Performance test:

[0144] The tensile strength of the novel three-component blended polyurea thermoplastic elastomer is 16.5 MPa, and the elongation at break is 820%.

[0145] Example 7

[0146] The solvent used in Example 7 is a mixed solvent of toluene and acetone (mass ratio 3:1).

[0147] Into a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube, add 13.6 g of hexamethylene diisocyanate and 68 g of a mixed solvent. Dissolve 30.3 g of Compound VII with a molecular weight of 3000 g / mol in 150 g of the mixed solvent, and slowly add it dropwise using the constant-pressure dropping funnel. After the addition is complete, continue stirring for 20 min. Mix 4.68 g of Compound NH2CH2CH(CH3)CH2CH2CH2NH2 and 2.3 g of 3,3'-diaminodipropylamine, dissolve them in 35 g of the mixed solvent, and then add them dropwise to the reaction system and react at 25 °C for 20 min to obtain Polymer-1.

[0148] Add 31.1 g of hexamethylene diisocyanate and 156 g of a mixed solvent into a four-necked flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 52.4 g of the compound of Formula VIII with a molecular weight of 2000 g / mol in 262 g of the mixed solvent, and slowly add it dropwise using the constant-pressure dropping funnel. After the addition is complete, continue stirring and reacting for 20 min. Dissolve 18.3 g of NH2CH2CH(CH3)CH2CH2CH2NH2 and 0.11 g of pentylamine in 92 g of the mixed solvent, slowly add it dropwise using the constant-pressure dropping funnel, and continue stirring and reacting for 20 min after the addition is complete to obtain Polymer-2.

[0149] Mix Polymer-1 and Polymer-2 in a molar ratio of 1:3.5, then add 0.2 wt% stannous octoate, and heat to 70 °C for reaction for 18 h to obtain a polymer with a polysiloxane-polyurea and polyether-polyurea structure having the structure of Formula (VI).

[0150] Mix 43 parts of polysiloxane-polyurea (I) with a hard segment content of 40 wt% (where the R value is 0.98), 57 parts of polyether-polyurea (II) with a hard segment content of 48 wt% (where the R value is 1.01), and 10 parts of the polymer (VI) having a polysiloxane-polyurea and polyether-polyurea structure in 5 times the amount of the mixed solvent. After stirring evenly, pour it into a polytetrafluoroethylene mold, cure at room temperature, and dry at 50 °C for 24 h to obtain a novel three-component blended polyurea thermoplastic elastomer. Wherein, in the polysiloxane-polyurea (I) and polyether-polyurea (II), X is a hexamethylene diisocyanate chain segment, and Y is CH2CH2CH2.

[0151] Performance test:

[0152] The tensile strength of the novel three-component blended polyurea thermoplastic elastomer is 50.4 MPa, and the elongation at break is 121%.

[0153] Comparative Example 1

[0154] Perform performance testing on the polysiloxane-polyurea thermoplastic elastomer (I) with a hard segment content of 22 wt% used in Example 1. The test results are as follows: the tensile strength is 13.23 MPa, and the elongation at break is 597%.

[0155] Comparative Example 2

[0156] Perform performance testing on the polyether-polyurea (II) with a hard segment content of 25 wt% used in Example 1. The test results are as follows: the tensile strength is 24.12 MPa, the elongation at break is 346%, and the water absorption rate after soaking in water at room temperature for 40 d is greater than 3.5%.

[0157] Comparative Example 3

[0158] Preparation of polysiloxane - polyether - polyurea:

[0159] Prepare a mixed solvent of toluene and acetone according to a mass ratio of 2:1. Add 2.6235 g of 4,4'-dicyclohexylmethane diisocyanate and 12.5 g of the mixed solvent to a flask equipped with a reflux condenser, a T-shaped three-way piston, a constant-pressure dropping funnel, and a drying tube. Dissolve 2 g of polyether with a molecular weight of 2000 g / mol and 2 g of polysiloxane with a molecular weight of 3000 g / mol in 20 g of the mixed solvent, and add it dropwise while stirring and reacting for 20 min. Subsequently, dissolve 0.7747 g of 2-methyl-1,5-diaminopentane in the mixed solvent, add it dropwise to the prepolymer, and stir and react for 20 min.

[0160] Remove the solvent from the solution obtained from the above reaction, pour it into a polytetrafluoroethylene mold, cure it at room temperature, and dry it in a vacuum drying oven at 50 °C for 24 h to obtain a polysiloxane - polyether - polyurea thermoplastic elastomer.

[0161] Performance test: The tensile strength of the polysiloxane - polyether - polyurea is 15.28 MPa, and the elongation at break is 463%.

[0162] Comparative Example 4

[0163] Preparation of polysiloxane - polyurea / polyether - polyurea blend:

[0164] Prepare a mixed solvent of toluene and acetone according to a mass ratio of 4:1. Stir 40 parts of polysiloxane - polyurea (Ⅰ) with a hard segment content of 16 wt% (where the R value is 0.99) and 60 parts of polyether - polyurea (Ⅱ) with a hard segment content of 16 wt% (where the R value is 1.02) used in Example 6 evenly in the mixed solvent. Remove the solvent from the obtained blend solution, pour it into a polytetrafluoroethylene mold, cure it at room temperature, and dry it in a vacuum drying oven at 50 °C for 24 h to obtain a polysiloxane - polyurea / polyether - polyurea thermoplastic elastomer.

[0165] Performance test: The tensile strength of the polysiloxane - polyurea / polyether - polyurea blend is 5.87 MPa, and the elongation at break is 137%.

[0166] Comparative Example 5

[0167] Preparation of polysiloxane - polyurea / polyether - polyurea blend:

[0168] A mixed solvent of cyclohexane and isopropanol was prepared according to a mass ratio of 2:1. 50 parts of polysiloxane-polyurea (Ⅰ) with a hard segment content of 16 wt% used in Example 6 (where the R value was 0.99), 50 parts of polyether-polyurea (Ⅱ) with a hard segment content of 16 wt% (where the R value was 1.02), and 8 parts of polysiloxane-polyether-polyurea prepared in Comparative Example 3 were mixed in the mixed solvent and stirred evenly. The resulting blend solution was removed of the solvent, poured into a polytetrafluoroethylene mold, cured at room temperature, and dried in a vacuum drying oven at 50 °C for 24 h to obtain a polysiloxane-polyurea / polyether-polyurea thermoplastic elastomer.

[0169] Performance test: The tensile strength of the polysiloxane-polyurea / polyether-polyurea thermoplastic elastomer was 6.12 MPa, and the elongation at break was 153%.

[0170] By comparing Comparative Examples 1, 2 and Example 5, it can be found that the blending method can compensate for the strength defect of polysiloxane-polyurea and retain the water resistance of silicone. In Comparative Example 4, the two polyureas were directly blended in a solvent without adding any compatibilizer, and the performance of the prepared polysiloxane-polyurea / polyether-polyurea thermoplastic elastomer was relatively poor. When the polysiloxane-polyether-polyurea prepared in Comparative Example 3 was used as a polyurea compatibilizer in Comparative Example 5, the performance of the obtained polysiloxane-polyurea / polyether-polyurea was also poor, indicating that the compatibilization effect of polymers with other structures as compatibilizers is relatively poor.

[0171] As can be seen from the above examples, the present invention provides a novel three-component blended polyurea thermoplastic elastomer and its preparation method. The novel three-component blended polyurea thermoplastic elastomer of the present invention is composed of 20 - 70 parts of polysiloxane-polyurea, 30 - 80 parts of polyether-polyurea, and 3 - 20 parts of a polymer having polysiloxane-polyurea and polyether-polyurea structures. The hard segment content in the polysiloxane-polyurea and polyether-polyurea is independently 15 - 50 wt%, and the R value is independently 0.98 - 1.02. The present invention first prepares a polymer having polysiloxane-polyurea and polyether-polyurea structures, uses it as a compatibilizer, and then mixes it with polysiloxane-polyurea and polyether-polyurea to prepare a novel three-component blended polyurea thermoplastic elastomer, so that the prepared elastomer simultaneously has the excellent properties of weather resistance, hydrophobicity, temperature resistance, and flexibility of polysiloxane, as well as high strength and high modulus of polyurea, and has excellent comprehensive performance.

[0172] 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 novel three-component blended polyurea thermoplastic elastomer, characterized in that, The novel three-component blended polyurea thermoplastic elastomer is composed of 20-70 parts of polysiloxane-polyurea, 30-80 parts of polyether-polyurea, and 3-20 parts of a polymer having polysiloxane-polyurea and polyether-polyurea structures. The hard segment content in the polysiloxane-polyurea and polyether-polyurea is independently 15-50 wt%, and the R value is independently 0.98-1.02; The polysiloxane-polyurea has the general formula shown in formula (Ⅰ): The polyether-polyurea has the general formula shown in formula (Ⅱ): Wherein, n and r are independently selected from integers of 15-65; m and m' are independently selected from integers of 50-100; X is independently selected from one of the chain segments of dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate; Y is independently selected from one of (CH2)4, (CH2)5, (CH2)6, and CH2CH2CH2; The polymer having polysiloxane-polyurea and polyether-polyurea structures is selected from one of the general formulas shown in formula (Ⅲ), (Ⅳ), (Ⅴ), and (VI): Wherein, q is independently taken as an integer greater than 1 and less than or equal to 4; p and s are independently taken as integers of 2-4; o is independently selected from 50-100.

2. The preparation method of the novel three-component blended polyurea thermoplastic elastomer according to claim 1, characterized in that, It includes the following steps: (1) Mix a diisocyanate compound and an aminopropyl-terminated polysiloxane in a solvent for reaction, and then add compound N to the reaction product and continue the reaction to obtain polymer-1; (2) Mix a diisocyanate compound and an amino-terminated polyether in a solvent for reaction, and then add compound N to the reaction product and continue the reaction to obtain polymer-2; Compound N is independently selected from one or more of chain extender E, capping agent F, chain extender G, chain extender H, and chain extender I; (3) Mix polymer-1, polymer-2, and a catalyst and then carry out a reaction to obtain a polymer having polysiloxane-polyurea and polyether-polyurea structures; (4) Mix the polysiloxane-polyurea, polyether-polyurea, and the polymer having polysiloxane-polyurea and polyether-polyurea structures in a solvent, and then perform a drying treatment to obtain the novel three-component blended polyurea thermoplastic elastomer; The aminopropyl-terminated polysiloxane has the general formula shown in formula (Ⅶ): Wherein, n is selected from integers of 15-65; The amino-terminated polyether has the general formula shown in formula (Ⅷ): Wherein, r is selected from integers of 15-65; The chain extender E is selected from one or more of NH2(CH2)4NH2, NH2(CH2)5NH2, NH2(CH2)6NH2, and NH2CH2CH(CH3)CH2CH2CH2NH2; the capping agent F is selected from one or more of CH3(CH2)2NH2, CH3(CH2)3NH2, CH3(CH2)4NH2, and CH3(CH2)5NH2; The chain extender G has the general formula shown in formula (Ⅸ): Wherein, p is independently taken as an integer of 2-4; The chain extender H has the general formula shown in formula (Ⅹ): Wherein, q is independently taken as an integer greater than 1 and less than or equal to 4; The chain extender I has the general formula shown in formula (Ⅺ): Wherein, s independently takes an integer from 2 to 4.

3. According to the preparation method described in claim 2, characterized in that, In the steps (1), (2) and (4), the solvent independently comprises one or more of N,N-dimethylformamide, acetone, tetrahydrofuran, isopropanol, n-hexane, toluene and cyclohexane.

4. According to the preparation method described in claim 2 or 3, characterized in that, In the steps (1) and (2), the diisocyanate compound independently comprises one or more of dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and toluene diisocyanate.

5. The preparation method according to claim 4, characterized in that, In the step (1), the mass ratio of the diisocyanate compound, the terminal amino propyl polysiloxane, the solvent and the compound N is 3-26:6-70:70-400:0.5-9.

6. The preparation method according to claim 2 or 3 or 5, characterized in that, In the step (2), the mass ratio of the diisocyanate compound, the terminal amino polyether, the solvent and the compound N is 5-65:22-165:120-1000:0.5-20; in the step (3), the molar ratio of the polymer-1 and the polymer-2 is 1:1.5-5.

0.

7. The preparation method according to claim 6, characterized in that, In the steps (1) and (2), the reaction temperature is independently 20-30°C, and the reaction time is independently 10-30 min; in the step (3), the reaction temperature is 50-110°C, and the reaction time is 8-24 h.

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