Terminal amine liquid nitrile rubber, method for producing the same, and silicon-containing terminal amine liquid nitrile rubber

Abstract

The present application relates to the technical field of nitrile rubber, in particular to an amine-terminated liquid nitrile rubber, a preparation method thereof and a silicon-containing amine-terminated liquid nitrile rubber. The method comprises the following steps: (1) carrying out an amino protection reaction on a compound containing amino and hydroxyl groups and an amino protection agent to obtain an amino protection product; (2) carrying out an acyl chloride reaction on an end carboxyl liquid nitrile rubber and an acyl chloride reagent to obtain an acyl chloride product; (3) carrying out a substitution reaction on the amino protection product and the acyl chloride product to obtain a substitution product; and (4) carrying out an amino deprotection reaction on the substitution product to obtain an amine-terminated liquid nitrile rubber. The preparation method of the amine-terminated liquid nitrile rubber provided in the present application is simple to operate, and the reaction mechanism is clear. The modified liquid nitrile rubber has a wider functional modification and application prospect, and is suitable for industrialization promotion.

Description

Technical Field

[0001] This invention relates to the field of nitrile rubber technology, specifically to an amine-terminated liquid nitrile rubber and its preparation method, and a silicon-terminated amine-terminated liquid nitrile rubber. Background Technology

[0002] Amino-terminated liquid nitrile butadiene rubber (ATBN) refers to liquid nitrile butadiene polymers containing amino groups (-NH2) at the chain ends. Introducing amino groups into liquid nitrile butadiene rubber can improve its adhesion, low-temperature resistance, and electrical insulation properties, making it suitable for preparing high-quality adhesives, sealing materials, anti-corrosion coatings, and water-soluble electrophoretic coatings, with wide applications in defense, military, and high-tech shipbuilding. Furthermore, the introduction of amino groups can activate the nitrile butadiene rubber, providing more possibilities for performance improvement and expanding its application range.

[0003] However, there is currently no domestic technology for preparing terminal amine-terminated liquid nitrile butadiene rubber (NBR), and it is mainly dependent on imports. Therefore, there is an urgent need to provide a method for preparing terminal amine-terminated liquid NBR and a silicon-containing terminal amine-terminated liquid NBR. Summary of the Invention

[0004] The purpose of this invention is to address the gap in the domestic preparation of terminal amine-based liquid nitrile rubber, and to provide a terminal amine-based liquid nitrile rubber and its preparation method, as well as a silicon-containing terminal amine-based liquid nitrile rubber.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for preparing amine-terminated liquid nitrile rubber, wherein the method includes the following steps:

[0006] (1) In the presence of a catalyst, a compound containing amino and hydroxyl groups is subjected to an amino protection reaction with an amino protecting agent to obtain an amino protected product.

[0007] (2) The carboxyl-terminated liquid nitrile rubber was subjected to an acyl chloride reaction with an acyl chloride reagent to obtain the acyl chloride product;

[0008] (3) The amino-protected product is subjected to a substitution reaction with the acyl chloride product to obtain the substituted product;

[0009] (4) The substituted product is subjected to an amino deprotection reaction to obtain terminal amine liquid nitrile rubber.

[0010] A second aspect of the present invention provides a terminal amine-based liquid nitrile rubber prepared by the method described in the first aspect of the present invention.

[0011] A third aspect of the present invention provides a silicon-terminated amine-based liquid nitrile rubber, wherein the silicon-terminated amine-based liquid nitrile rubber is a modified carboxyl-terminated liquid nitrile rubber, and at least some of the -OH groups in the modified carboxyl-terminated liquid nitrile rubber are replaced with groups shown in Formula 1:

[0012]

[0013] R1 and R2 are each individually selected from hydroxyl and / or alkyl groups, and R3 is selected from alkylene groups.

[0014] Through the above technical solution, this invention provides a method for preparing amine-terminated liquid nitrile butadiene rubber. First, the amino group in a compound containing amino and hydroxyl groups is protected. Then, using carboxyl-terminated liquid nitrile butadiene rubber as the starting material, chlorine is introduced through an acylation reaction. The protected amino group is then introduced onto the liquid nitrile butadiene rubber via a substitution reaction between chlorine and hydroxyl groups. Subsequently, the protected amino group undergoes a deamination protection reaction, thereby achieving end-amino group amination of the liquid nitrile butadiene rubber. The method for preparing amine-terminated liquid nitrile butadiene rubber provided by this invention is simple to operate and has a clear reaction mechanism, giving liquid nitrile butadiene rubber broader functionalization modification and application prospects, making it suitable for industrial promotion.

[0015] The present invention provides an amine-terminated liquid nitrile rubber with a viscosity of 170-240 Pa·s at 27°C, an amine value of 40-60 mg KOH / g, free amine <4%, a number-average molecular weight between 3500-4500 g / mol, a glass transition temperature <-45°C, and good aging resistance, ozone resistance, physiological inertness, and high and low temperature resistance.

[0016] The present invention provides a silicon-terminated amine-based liquid nitrile rubber with an amine value of 50-60 mgKOH / g, a glass transition temperature of <-55℃, and better aging resistance, ozone resistance, physiological inertness, and high and low temperature resistance. Attached Figure Description

[0017] Figure 1 The image shows the 1H NMR spectrum of the silicon-terminated amine-containing liquid nitrile rubber obtained in Example 2. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] A first aspect of the present invention provides a method for preparing terminal amine-terminated liquid nitrile rubber, wherein the method includes the following steps:

[0020] (1) In the presence of a catalyst, a compound containing amino and hydroxyl groups is subjected to an amino protection reaction with an amino protecting agent to obtain an amino protected product.

[0021] (2) The carboxyl-terminated liquid nitrile rubber was subjected to an acyl chloride reaction with an acyl chloride reagent to obtain the acyl chloride product;

[0022] (3) The amino-protected product is subjected to a substitution reaction with the acyl chloride product to obtain the substituted product;

[0023] (4) The substituted product is subjected to an amino deprotection reaction with a deprotecting agent to obtain terminal amine liquid nitrile rubber.

[0024] In step (1):

[0025] The present invention aims to introduce an amino group (-NH2) into nitrile rubber to activate the end groups of the nitrile rubber and improve its activity. The present invention does not specifically limit the compounds containing amino and hydroxyl groups; any compound containing amino and hydroxyl groups that can achieve the purpose of the present invention according to the preparation method described herein can be used in the present invention. For example, the compound containing amino and hydroxyl groups can be a substance with the general formula NH2-R-OH, wherein R is a substituted or unsubstituted alkyl group, preferably a substituted or unsubstituted C2-C group. 20 The alkyl group; or R is a carbon skeleton containing groups such as ketone, carbonyl, carboxyl, ester, cyano, aryl, silyl, siloxy, carbon-carbon double bond, and carbon-carbon triple bond on the carbon chain.

[0026] In one embodiment of the present invention, the compound containing amino and hydroxyl groups is selected from 2-hydroxyethylamine (NH2-CH2-CH2-OH) and p-hydroxyphenylethylamine. 2-(3,4-Dihydroxyphenyl)ethylamine 2-Amino-1-phenylethanol One or more of the hydrolysis products of aminosilane coupling agents.

[0027] In this invention, the compounds containing amino and hydroxyl groups can be commercially available products or synthesized using known methods, and this invention does not impose any special limitations on them.

[0028] In one embodiment of the present invention, the aminosilane coupling agent hydrolysis product is obtained by hydrolysis of the aminosilane coupling agent; wherein the aminosilane coupling agent is selected from one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, (3-aminopropyl)dimethylethoxysilane, and 3-aminopropylmethyldiethoxysilane.

[0029] In this invention, the aminosilane coupling agent contains siloxane, which can react with water to release alkyl groups and introduce hydroxyl groups, thereby forming a compound that contains both amino and hydroxyl groups.

[0030] In one embodiment of the present invention, the preparation method of the aminosilane coupling agent hydrolysis product includes: mixing the aminosilane coupling agent with water, preferably deionized water, at a volume ratio of 1:2-6, reacting at 40-80°C, preferably 50-70°C for 0.5-3 hours until the solution becomes colorless and transparent, and then performing vacuum distillation to obtain the aminosilane coupling agent hydrolysis product.

[0031] In one embodiment of the present invention, the amino protecting agent is selected from one or more of tert-butyloxycarbonyl compounds, benzyloxycarboxyl compounds, 2-biphenyl-2-propoxycarbonyl compounds, phthalimide compounds, triphenylmethyl compounds, formyl compounds, and trifluoroacetyl compounds, preferably tert-butyloxycarbonyl compounds, and more preferably ditert-butyl dicarbonate.

[0032] Different amino protecting agents correspond to different reaction conditions. This invention does not impose special limitations on the operating conditions of the amino protection reaction; known reaction conditions can be selected for different amino protecting agents. This invention uses di-tert-butyl dicarbonate as an example of an amino protecting agent to illustrate the amino protection reaction; other types of amino protecting agents will not be described in detail.

[0033] In one embodiment of the present invention, when the amino protecting agent is di-tert-butyl dicarbonate, the operating conditions for the amino protection reaction include:

[0034] The amino protection reaction is carried out in solvent I; wherein solvent I is selected from one or more of methanol, acetone, and tetrahydrofuran.

[0035] Preferably, based on 1g of the amino and hydroxyl-containing compound, the amount of solvent I is 4-15g, more preferably 6-10g.

[0036] Preferably, the catalyst is selected from one or more of triethylamine, sodium carbonate, sodium bicarbonate, and sodium hydroxide.

[0037] Preferably, the mass ratio of the amino and hydroxyl-containing compound, the amino protecting agent, and the catalyst is 1:1-2.5:0.5-2, more preferably 1:1-1.5:1-1.5.

[0038] Preferably, the reaction temperature of the amino protection reaction is room temperature, and the reaction time is 10-20 hours, more preferably 15-16 hours. Room temperature has a known meaning, for example, it can be 20-35°C.

[0039] In this invention, the amino and hydroxyl-containing compounds and the amino protecting agent are first dissolved in solvent I, and then the solution containing the amino protecting agent is added dropwise to the solution containing the amino and hydroxyl-containing compounds at room temperature. After the addition is complete, the reaction time is recorded.

[0040] Preferably, after the amino protection reaction is completed, the reaction solution is subjected to vacuum distillation to remove solvent I. Then, water is added first, followed by the extraction agent, and extraction is performed. The extracted phase is then rotary evaporated to obtain the amino-protected product. The extraction agent is selected from dichloromethane and / or trichloromethane.

[0041] In step (2):

[0042] In one embodiment of the present invention, the acyl chloride reagent is selected from one or more of thionyl chloride, phosphorus pentachloride, phosphorus trichloride, and phosphorus oxychloride, preferably thionyl chloride.

[0043] In one embodiment of the present invention, the ratio of the carboxyl-terminated liquid nitrile rubber to the acyl chloride reagent is 1g:30-70mL, preferably 1g:45-55mL.

[0044] In one embodiment of the present invention, the acyl chloride reaction is carried out in solvent II; wherein, solvent II is selected from one or more of toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene.

[0045] In one embodiment of the present invention, based on 1g of the terminal carboxyl liquid nitrile rubber, the amount of solvent II is 1-10mL, preferably 2.5-5mL.

[0046] In this invention, in order to improve the mixing effect of carboxyl-terminated liquid nitrile rubber and acyl chloride reagent in solvent II, it is preferable to first disperse the carboxyl-terminated liquid nitrile rubber in solvent II, and then add the acyl chloride reagent to solvent II, and start the temperature rise reaction after treatment under ultrasonic conditions for 0.5-2 hours.

[0047] In one embodiment of the present invention, the acyl chloride reaction is carried out under the protection of an inert gas. In this invention, the inert gas refers to a gas that does not react with any of the substances involved in the acyl chloride reaction; for example, the inert gas may be nitrogen.

[0048] In one embodiment of the present invention, the reaction temperature of the acyl chloride reaction is 60-90°C, preferably 70-80°C; and the reaction time of the acyl chloride reaction is 8-20 h, preferably 12-15 h.

[0049] In one embodiment of the present invention, after the acyl chloride reaction is completed, at room temperature, solvent II is added again to the reaction solution that has completed the acyl chloride reaction, that is, to the obtained reaction product, and then distillation is performed, preferably by vacuum distillation, to remove solvent II and unreacted acyl chloride reagent, so as to obtain the acyl chloride product.

[0050] In this invention, the purpose of adding solvent II again is to dissolve the acyl chloride product generated in the reaction. The volume ratio of the amount of solvent II added again to the amount of solvent II added previously is 1:0.5-1.5, preferably 1:0.9-1.1.

[0051] In step (3):

[0052] In one embodiment of the present invention, the mass ratio of the acyl chloride product to the amino protected product is 1:1-2.5, preferably 1:1.5-2.

[0053] In one embodiment of the present invention, the substitution reaction is carried out in solvent III; wherein solvent III is selected from one or more of dichloromethane, trichloromethane, dichloroethane, and trichloroethane.

[0054] In one embodiment of the present invention, based on 1g of the acyl chloride product, the amount of solvent III is 2-10g, preferably 5-6g.

[0055] In one embodiment of the present invention, the substitution reaction comprises: first dissolving the acyl chloride product in solvent III, then adding the amino protected product dropwise, and then reacting at room temperature for 6-18 h, preferably 8-12 h.

[0056] In one embodiment of the present invention, the dropwise addition is carried out at 0-10°C, preferably 0-5°C. Furthermore, in this invention, the dropwise addition can be carried out under ice bath conditions, and more preferably under ice bath conditions with stirring.

[0057] In one embodiment of the present invention, after the substitution reaction is completed, the reaction solution that has completed the substitution reaction, i.e. the substitution reaction product, is first subjected to vacuum distillation to remove solvent III. Then, a purification reagent is added, and rotary evaporation and vacuum drying are performed sequentially to obtain the substitution product.

[0058] In this invention, the purification reagent is one or more of n-hexane, n-heptane, and n-octane, and the amount of purification reagent added is 10-20g based on 1g of the amino-protected product.

[0059] In step (4):

[0060] In this invention, di-tert-butyl dicarbonate is used as an example of amino deprotecting agent to illustrate the amino deprotection reaction. The amino deprotection reactions corresponding to other amino protecting agents can be carried out by known methods, and will not be described in detail here.

[0061] In one embodiment of the present invention, when the amino protecting agent is ditert-butyl dicarbonate, the deprotecting agent is selected from one or more of trifluoroacetic acid and / or dioxane hydrochloride solution, preferably trifluoroacetic acid.

[0062] In one embodiment of the present invention, the deamination protection reaction is carried out in solvent IV, wherein solvent IV is selected from one or more of dichloromethane, trichloromethane, dichloroethane, trichloroethane, and dimethylformamide.

[0063] In one embodiment of the present invention, the mass ratio of the substitution product to the deprotecting agent is 1:0.3-1, preferably 1:0.4-0.6; the mass ratio of the substitution product to solvent IV is 1:4-10, preferably 6-8.

[0064] In one embodiment of the present invention, the reaction temperature of the amino deprotection reaction is room temperature, and the reaction time of the amino deprotection reaction is 0.2-2.5 h, preferably 0.5-1 h.

[0065] A second aspect of the present invention provides a terminal amine-based liquid nitrile rubber prepared by the method described in the first aspect of the present invention.

[0066] In the amine-terminated liquid nitrile butadiene rubber prepared by the method described in the first aspect of the present invention, at least a portion of the -OH groups of the carboxyl-terminated liquid nitrile butadiene rubber are replaced by amino-containing groups from compounds containing amino and hydroxyl groups. The structure of the substituted amine-terminated liquid nitrile butadiene rubber can be as follows:

[0067] Equations 1-1 to 1-4 are shown below:

[0068]

[0069]

[0070] In this invention, for ease of description, structural unit A, structural unit B, structural unit C, and end cap are connected together to form a complete general formula. Equations 1-1 to 1-4 are for illustrative purposes only and do not represent that structural unit A, structural unit B, and structural unit C are connected in the order of the general formula. Here, x, y, and z are each independently selected from any integer between 5 and 1000.

[0071] In one embodiment of the present invention, the amine-terminated liquid nitrile rubber has an amine value of 40-60 mg KOH / g, free amine <4%, a number-average molecular weight of 3500-4500 g / mol, a viscosity of 170-240 Pa·s at 27°C, and a glass transition temperature <-45°C.

[0072] A third aspect of the present invention provides a silicon-terminated amine-based liquid nitrile rubber, wherein the silicon-terminated amine-based liquid nitrile rubber is a modified carboxyl-terminated liquid nitrile rubber, and at least some of the -OH groups in the modified carboxyl-terminated liquid nitrile rubber are replaced with groups shown in Formula 1:

[0073]

[0074] R1 and R2 are each individually selected from hydroxyl and / or alkyl groups, and R3 is selected from alkylene groups.

[0075] In a preferred embodiment of the present invention, the alkyl group is selected from straight-chain or branched C1-C5 alkyl groups, preferably methyl, ethyl, or n-propyl.

[0076] In a preferred embodiment of the present invention, the alkylene group is selected from straight-chain or branched C1-C5 alkylene groups, preferably methylene, ethylene, propylene, or butylene.

[0077] In a preferred embodiment of the present invention, the general structural formula of the modified carboxyl-terminated liquid nitrile rubber after at least some of the -OH groups in the terminal carboxyl groups are replaced by groups shown in Formula 1 is Formula 1-1:

[0078]

[0079] In a preferred embodiment of the present invention, the amine value of the silicon-terminated amine-containing liquid nitrile rubber is 50-60 mgKOH / g, preferably 55-58 mgKOH / g.

[0080] In a preferred embodiment of the present invention, the free amine of the silicon-terminated amine-containing liquid nitrile rubber is 2.9-3.8%, the number average molecular weight is 3800-4450 g / mol, the viscosity at 27°C is 185-235 Pa·s, and the glass transition temperature is -58 to -56°C.

[0081] In a preferred embodiment of the present invention, the silicon-terminated amine-based liquid nitrile rubber is prepared using the method described in the first aspect of the present invention, wherein the compound containing amino and hydroxyl groups is a hydrolysis product of an aminosilane coupling agent, the amino protecting agent is di-tert-butyl dicarbonate, the acyl chloride reagent is sulfoxide, and the deprotecting agent is trifluoroacetic acid.

[0082] The following embodiments will further illustrate the present invention, but are not intended to limit the invention.

[0083] Among them, the carboxyl-terminated liquid nitrile rubber is from Lanzhou Petrochemical ANBR1300X16, with a number-average molecular weight of 3830 g / mol.

[0084] Example 1

[0085] (1) Add 10 mL of KH550 and 40 mL of deionized water to a three-necked flask equipped with a stirrer, then heat to 60 °C and stir for 1 h until the solution becomes colorless and transparent. After the reaction is complete, the solution is distilled under reduced pressure to remove the deionized water and obtain the hydrolysis product.

[0086] 5g of the above hydrolysis product and 6g of triethylamine were added to 30g of methanol. After stirring thoroughly, 18g of a 30wt% methanol solution of ditert-butyl dicarbonate was slowly added dropwise. After the addition was complete, the reaction was carried out at room temperature for 16h. After the reaction was complete, methanol was removed by vacuum distillation. The product was added to deionized water and extracted with dichloromethane to obtain the extract phase. The extract phase was then rotary evaporated to obtain the amino-protected product.

[0087] (2) Dissolve 2g of terminal carboxyl liquid nitrile rubber in 5mL of toluene and place it in a three-necked flask. Then add 90mL of thionyl chloride and sonicate for 1h. Then raise the temperature to 70℃ for acyl chloride reaction and react for 13h under nitrogen protection. After the reaction is complete, cool to room temperature and add 90mL of toluene. Remove toluene and unreacted thionyl chloride by vacuum distillation to obtain the acyl chloride product.

[0088] (3) Dissolve 1g of the above acyl chloride product in 5g of dichloromethane, and slowly add 1.5g of the above amino protected product at 0℃. After the addition is completed, stir the reaction magnetically at room temperature for 10h. After the reaction is completed, perform vacuum distillation to remove dichloromethane, and then add 12.5g of n-hexane for purification. The substituted product is obtained by rotary evaporation and vacuum drying.

[0089] (4) Dissolve 1g of the above-mentioned substituted product in 7g of dichloromethane, add 2.3g of 25wt% TFA solution, react at room temperature for 0.5h, and after the reaction is completed, obtain silicon-terminated amine-based liquid nitrile rubber by rotary evaporation and vacuum drying.

[0090] The reaction equations for each step in Example 1 are as follows:

[0091] Step (1)

[0092]

[0093] Step (2)

[0094] Step (3)

[0095] Step (4)

[0096] Example 2

[0097] (1) Add 10 mL of KH550 and 35 mL of deionized water to a three-necked flask equipped with a stirrer, then heat to 50 °C and stir for 1.5 h until the solution becomes colorless and transparent. After the reaction is complete, the solution is distilled under reduced pressure to remove the deionized water and obtain the hydrolysis product.

[0098] 5g of the above hydrolysis product and 5g of triethylamine were added to 30g of methanol. After stirring thoroughly, 20g of a methanol solution of 30wt% ditert-butyl dicarbonate was slowly added dropwise. After the addition was complete, the reaction was carried out at room temperature for 16h. After the reaction was complete, methanol was removed by vacuum distillation. The product was added to deionized water and extracted with dichloromethane to obtain the extract phase. The extract phase was then rotary evaporated to obtain the amino-protected product.

[0099] (2) Dissolve 2g of terminal carboxyl liquid nitrile rubber in 5mL of toluene and place it in a three-necked flask. Then add 100mL of thionyl chloride and sonicate for 1h. Then raise the temperature to 80℃ for acyl chloride reaction and react for 14h under nitrogen protection. After the reaction is complete, cool to room temperature and add 100mL of toluene. Remove toluene and unreacted thionyl chloride by vacuum distillation to obtain the acyl chloride product.

[0100] (3) Dissolve 1g of the above acyl chloride product in 5g of dichloromethane, and slowly add 2g of the above amino protected product at 3°C. After the addition is completed, stir the reaction magnetically at room temperature for 12h. After the reaction is completed, perform vacuum distillation to remove dichloromethane, and then add 12.5g of n-hexane for purification. The substituted product is obtained by rotary evaporation and vacuum drying.

[0101] (4) Dissolve 1g of the above-mentioned substituted product in 7g of dichloromethane, add 2.0g of 25wt% TFA solution, react at room temperature for 1h, and after the reaction is completed, obtain silicon-terminated amine-based liquid nitrile rubber by rotary evaporation and vacuum drying.

[0102] Example 3

[0103] (1) Add 10 mL of KH550 and 20 mL of deionized water to a three-necked flask equipped with a stirrer, then heat to 40 °C and stir for 2 h until the solution becomes colorless and transparent. After the reaction is complete, the solution is distilled under reduced pressure to remove the deionized water and obtain the hydrolysis product.

[0104] The above 5g hydrolysis product and 3g triethylamine were added to 30g methanol. After stirring thoroughly, 30g of a 30wt% ditert-butyl dicarbonate methanol solution was slowly added dropwise. After the addition was complete, the reaction was carried out at room temperature for 18h. After the reaction was complete, the methanol was removed by vacuum distillation. The product was added to deionized water and extracted with dichloromethane to obtain the extract phase. The extract phase was then rotary evaporated to obtain the amino-protected product.

[0105] (2) Dissolve 2g of terminal carboxyl liquid nitrile rubber in 5mL of toluene and place it in a three-necked flask. Then add 120mL of thionyl chloride and sonicate for 1h. Then raise the temperature to 65℃ for acyl chloride reaction and react for 18h under nitrogen protection. After the reaction is complete, cool to room temperature and add 120mL of toluene. Remove toluene and unreacted thionyl chloride by vacuum distillation to obtain the acyl chloride product.

[0106] (3) Dissolve 1g of the above acyl chloride product in 5g of dichloromethane, slowly add 1g of the above amino protected product at 5°C, and after the addition is complete, stir the reaction magnetically at room temperature for 6h. After the reaction is complete, perform vacuum distillation to remove dichloromethane, and then add 12.5g of n-hexane for purification. The substituted product is obtained by rotary evaporation and vacuum drying.

[0107] (4) Dissolve 1g of the above-mentioned substituted product in 7g of dichloromethane, add 1.5g of 25wt% TFA solution, react at room temperature for 1h, and after the reaction is completed, obtain silicon-terminated amine-based liquid nitrile rubber by rotary evaporation and vacuum drying.

[0108] Example 4

[0109] (1) Add 10 mL of KH550 and 60 mL of deionized water to a three-necked flask equipped with a stirrer, then heat to 75 °C and stir for 0.5 h until the solution becomes colorless and transparent. After the reaction is complete, the solution is distilled under reduced pressure to remove the deionized water and obtain the hydrolysis product.

[0110] 5g of the above hydrolysis product and 8g of triethylamine were added to 30g of methanol. After stirring thoroughly, 35g of a 30wt% ditert-butyl dicarbonate methanol solution was slowly added dropwise. After the addition was complete, the reaction was carried out at room temperature for 12h. After the reaction was complete, methanol was removed by vacuum distillation. The product was added to deionized water and extracted with dichloromethane to obtain the extract phase. The extract phase was then rotary evaporated to obtain the amino-protected product.

[0111] (2) Dissolve 2g of terminal carboxyl liquid nitrile rubber in 5mL of toluene and place it in a three-necked flask. Then add 60mL of thionyl chloride and sonicate for 1h. Then raise the temperature to 85℃ for acyl chloride reaction and react for 10h under nitrogen protection. After the reaction is complete, cool to room temperature and add 60mL of toluene. Remove toluene and unreacted thionyl chloride by vacuum distillation to obtain the acyl chloride product.

[0112] (3) Dissolve 1g of the above acyl chloride product in 5g of dichloromethane, and slowly add 2.5g of the above amino protected product at 0℃. After the addition is completed, stir the reaction magnetically at room temperature for 14h. After the reaction is completed, perform vacuum distillation to remove dichloromethane, and then add 12.5g of n-hexane for purification. The substituted product is obtained by rotary evaporation and vacuum drying.

[0113] (4) Dissolve 1g of the above-mentioned substituted product in 7g of dichloromethane, add 3.0g of 25% TFA solution, react at room temperature for 1.5h, and after the reaction is completed, obtain silicon-terminated amine-based liquid nitrile rubber by rotary evaporation and vacuum drying.

[0114] Example 5

[0115] Similar to Example 4, except that the hydrolysis in step (1) is omitted and the hydrolysis product is replaced with an equal amount of 2-hydroxyethylamine.

[0116] The general structural formula of the obtained amine-terminated liquid nitrile rubber, in which at least some of the -OH groups in the carboxyl-terminated liquid nitrile rubber are replaced by amino-containing groups, is as follows:

[0117]

[0118] Example 6

[0119] Similar to Example 4, except that the hydrolysis in step (1) is omitted and the hydrolysis product is replaced with an equal amount of p-hydroxyphenylethylamine.

[0120] The general structural formula of the obtained amine-terminated liquid nitrile rubber, in which at least some of the -OH groups in the carboxyl-terminated liquid nitrile rubber are replaced by amino-containing groups, is as follows:

[0121]

[0122] Example 7

[0123] Similar to Example 4, except that the hydrolysis in step (1) is omitted and the hydrolysis product is replaced with an equal amount of 2-amino-1-phenylethanol.

[0124] The general structural formula of the obtained amine-terminated liquid nitrile rubber, in which at least some of the -OH groups in the carboxyl-terminated liquid nitrile rubber are replaced by amino-containing groups, is as follows:

[0125]

[0126] Test Example 1

[0127] The silicon-terminated amine-containing liquid nitrile rubber obtained in Example 2 was subjected to NMR analysis, and the test results are as follows: Figure 1 As shown.

[0128] from Figure 1 The 1H NMR spectrum of the modified liquid nitrile rubber shows that: 1 H-NMR (400MHz, CDCl3), the peak at δ6.33(a) is -OH and the peak at δ1.43(b) is -NH2. These two characteristic peaks prove that the silicon-terminated amine-based liquid nitrile rubber was successfully prepared.

[0129] Test Example 2

[0130] The properties of the terminal amine-terminated liquid nitrile rubbers prepared in Examples 1-7 were tested, and the results are shown in Table 1.

[0131] Viscosity was measured using a rotational viscometer. Free amine value was determined according to GB / T 6365-2006. Glass transition temperature was determined according to GB / T 29611-2013.

[0132] The carboxyl conversion rate was determined by acid-base titration, specifically as follows: Equal masses of raw material carboxyl-terminated liquid nitrile rubber and prepared amine-terminated liquid nitrile rubber were immersed in 0.5% HCl for 30 min, filtered, washed repeatedly with deionized water, and dried. Then, 1 g of each sample was immersed in an iodine flask containing 250 mL of 0.1 M calcium acetate solution and placed in a shaker for 24 h. 10 mL of the solution was then transferred to an Erlenmeyer flask and titrated with 0.1 mol / L NaOH solution using cresol red and thymol blue as indicators, with the titration ending in a color change from yellow to purplish-rose. The content was then calculated. The molar content of carboxyl groups in the raw material carboxyl-terminated liquid nitrile rubber is n1, and the molar content of carboxyl groups in the prepared amine-terminated liquid nitrile rubber is n2. The carboxyl conversion rate is equal to (n1-n2) / n1.

[0133] The amine value is determined by using the acid required to neutralize the sample, and is expressed in milligrams of potassium hydroxide.

[0134] Table 1

[0135]

[0136]

[0137] As can be seen from Table 1, the carboxyl conversion rate of the terminal amine liquid nitrile rubber prepared in Examples 1-7 is above 75%, and the amine value is between 40-60 mgKOH / g, with free amine <4%. This indicates that liquid nitrile rubber with amino-terminated groups was successfully prepared.

[0138] The amine-terminated liquid nitrile rubbers prepared in Examples 1-7 have a viscosity range of 170-240 Pa·s, a number-average molecular weight of 3500-4500 g / mol, and a glass transition temperature of <-45℃, indicating that the amine-terminated liquid nitrile rubbers have good flowability and low-temperature resistance, and have a wider range of modification and application possibilities.

[0139] In Examples 1-4, the silicon-terminated amine-based liquid nitrile rubber exhibits relatively good performance with a glass transition temperature of <-55℃. This is because the introduction of silane-containing structures further enhances the performance of the liquid nitrile rubber.

[0140] Within the scope of the inventive concept, various simple modifications can be made to the technical solution of the present invention, including combinations of specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not further describe the various possible combinations. However, these simple modifications and combinations should also be considered as part of the content disclosed in this invention and are all within the protection scope of this invention.

Claims

1. A method for preparing an amine-terminated liquid nitrile rubber, characterized in that, The method includes the following steps: (1) In the presence of a catalyst, a compound containing amino and hydroxyl groups is subjected to an amino-protecting reaction with an amino-protecting agent to obtain an amino-protected product; (2) The carboxyl-terminated liquid nitrile rubber was subjected to an acyl chloride reaction with an acyl chloride reagent to obtain the acyl chloride product; (3) The amino-protected product is subjected to a substitution reaction with the acyl chloride product to obtain the substituted product; (4) The substituted product is subjected to an amino deprotection reaction with a deprotecting agent to obtain terminal amine liquid nitrile rubber.

2. The preparation method according to claim 1, wherein, The compound containing amino and hydroxyl groups is selected from one or more of 2-hydroxyethylamine, p-hydroxyphenylethylamine, 2-(3,4-dihydroxyphenyl)ethylamine, 2-amino-1-phenylethanol, and aminosilane coupling agent hydrolysis products.

3. The preparation method according to claim 2, wherein, The aminosilane coupling agent hydrolysis product is obtained by hydrolysis of the aminosilane coupling agent; wherein the aminosilane coupling agent is selected from one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, (3-aminopropyl)dimethylethoxysilane, and 3-aminopropylmethyldiethoxysilane.

4. The preparation method according to claim 1, wherein, The amino protecting agent is selected from one or more of the following: tert-butyloxycarbonyl compounds, benzyloxycarboxyl compounds, 2-biphenyl-2-propoxycarbonyl compounds, phthalimide compounds, triphenylmethyl compounds, formyl compounds, and trifluoroacetyl compounds.

5. The preparation method according to claim 4, wherein, The amino protecting agent is a tert-butyloxycarbonyl compound.

6. The preparation method according to claim 5, wherein, The amino protecting agent is ditert-butyl dicarbonate.

7. The preparation method according to claim 6, wherein, When the amino protecting agent is di-tert-butyl dicarbonate, the operating conditions for the amino protection reaction include: The amino protection reaction is carried out in solvent I; wherein, solvent I is selected from one or more of methanol, acetone, and tetrahydrofuran; And / or, the catalyst is selected from one or more of triethylamine, sodium carbonate, sodium bicarbonate, and sodium hydroxide; And / or, the mass ratio of the amino and hydroxyl-containing compound, the amino protecting agent, and the catalyst is 1:1-2.5:0.5-2; And / or, the reaction temperature of the amino protection reaction is room temperature, and the reaction time of the amino protection reaction is 10-20 h.

8. The preparation method according to claim 7, wherein, The mass ratio of the amino and hydroxyl-containing compound, the amino protecting agent, and the catalyst is 1:1-1.5:1-1.5; And / or, the reaction time for the amino protection reaction is 15-16 h.

9. The preparation method according to claim 1, wherein, The acyl chloride reagent is selected from one or more of thionyl chloride, phosphorus pentachloride, phosphorus trichloride, and phosphorus oxychloride; And / or, the ratio of the terminal carboxyl liquid nitrile rubber to the acyl chloride reagent is 1g:30-70mL.

10. The preparation method according to claim 9, wherein, The acyl chloride reagent is thionyl chloride; And / or, the ratio of the terminal carboxyl liquid nitrile rubber to the acyl chloride reagent is 1g:45-55mL.

11. The preparation method according to claim 1, wherein, The acyl chloride reaction is carried out in solvent II; wherein solvent II is selected from one or more of toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene.

12. The preparation method according to claim 1 or 11, wherein, The acyl chloride reaction is carried out under inert gas protection.

13. The preparation method according to claim 12, wherein, The inert gas is nitrogen.

14. The preparation method according to claim 1 or 11, wherein, The reaction temperature of the acyl chloride reaction is 60-90℃, and the reaction time is 8-20h.

15. The preparation method according to claim 14, wherein, The reaction temperature of the acyl chloride reaction is 70-80℃, and the reaction time is 12-15h.

16. The preparation method according to claim 11, wherein, After the acyl chloride reaction is completed, solvent II is added again to the obtained reaction product at room temperature and then distilled to remove solvent II and unreacted acyl chloride reagent, thereby obtaining the acyl chloride product.

17. The preparation method according to claim 16, wherein, The distillation is vacuum distillation.

18. The preparation method according to claim 1, wherein, The mass ratio of the acyl chloride product to the amino protected product is 1:1-2.

5.

19. The preparation method according to claim 18, wherein, The mass ratio of the acyl chloride product to the amino protected product is 1:1.5-2; And / or, the substitution reaction takes 8-12 hours.

20. The preparation method according to claim 1 or 18, wherein, The substitution reaction is carried out in solvent III; wherein solvent III is selected from one or more of dichloromethane, trichloromethane, dichloroethane, and trichloroethane.

21. The preparation method according to claim 20, wherein, The substitution reaction process includes: first dissolving the acyl chloride product in solvent III, then adding the amino protected product dropwise, and then reacting at room temperature for 6-18 hours.

22. The preparation method according to claim 21, wherein, The addition was carried out at 0-10°C.

23. The preparation method according to claim 22, wherein, The temperature at which the drops are added is 0-5℃.

24. The preparation method according to claim 20, wherein, After the substitution reaction is completed, the substituted product is first subjected to vacuum distillation to remove solvent III, and then purification reagent is added. The product is then subjected to rotary evaporation and vacuum drying in sequence to obtain the substituted product.

25. The preparation method according to claim 24, wherein, The purification reagent is one or more of n-hexane, n-heptane, and n-octane, and the amount of the purification reagent added is 10-20g based on 1g of the amino-protected product.

26. The preparation method according to claim 1, wherein, The deprotecting agent is selected from trifluoroacetic acid and / or dioxane hydrochloride solution; And / or, the amino deprotection reaction is carried out in solvent IV, wherein solvent IV is selected from one or more of dichloromethane, trichloromethane, dichloroethane, trichloroethane, and dimethylformamide; And / or, the mass ratio of the substitution product to the deprotecting agent is 1:0.3-1; And / or, the temperature of the amino deprotection reaction is room temperature, and the reaction time of the amino deprotection reaction is 0.2-2.5 h.

27. The preparation method according to claim 26, wherein, The deprotecting agent is trifluoroacetic acid; And / or, the mass ratio of the substitution product to the deprotecting agent is 1:0.4-0.6; And / or, the temperature of the amino deprotection reaction is room temperature, and the reaction time of the amino deprotection reaction is 0.5-1 h.

28. An amine-terminated liquid nitrile rubber prepared by the method of any one of claims 1-27.

29. A liquid butadiene-acrylonitrile rubber containing silicon-terminated amine groups, characterized in that, The silicon-terminated amine-terminated liquid nitrile rubber is a modified carboxyl-terminated liquid nitrile rubber, wherein at least some of the -OH groups of the modified carboxyl-terminated liquid nitrile rubber are replaced with groups shown in Formula 1: Formula 1; R1 and R2 are each individually selected from hydroxyl or alkyl groups, and R3 is selected from alkylene groups.

30. The silicon-terminated amine-based liquid nitrile rubber according to claim 29, wherein, The alkyl group is selected from straight-chain or branched C1-C5 alkyl groups, and the alkylene group is selected from straight-chain or branched C1-C5 alkylene groups.

31. The silicon-terminated amine-containing liquid nitrile rubber according to claim 30, wherein, The alkyl group is selected from methyl, ethyl, and n-propyl, and the alkylene group is selected from methylene, ethylene, propylene, and butylene.

32. The silicon-terminated amine-based liquid nitrile rubber according to any one of claims 29-31, wherein, The amine value of the terminal amine group liquid nitrile rubber is 50-60 mg KOH / g.

33. The silicon-terminated amine-based liquid nitrile rubber according to claim 32, wherein, The amine value of the terminal amine group liquid nitrile rubber is 55-58 mgKOH / g.

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