Amino-terminated liquid nitrile rubber, preparation method thereof and silicon-containing amino-terminated liquid nitrile rubber

Abstract

The invention relates to the technical field of nitrile rubber, in particular to amino-terminated liquid nitrile rubber, a preparation method thereof and silicon-containing amino-terminated liquid nitrile rubber. The method comprises the following steps: (1) carrying out amino protection reaction on a compound containing amino and hydroxyl and an amino protective agent to obtain an amino protection product; (2) carrying out acylating chlorination reaction on the carboxyl-terminated liquid nitrile rubber and an acylating chlorination reagent to obtain an acylating chlorination product; (3) carrying out substitution reaction on the amino protection product and the acylating chlorination product to obtain a substitution product; and (4) carrying out amino deprotection reaction on the substitution product to obtain the amino-terminated liquid nitrile rubber. The preparation method of the amino-terminated liquid nitrile rubber provided by the invention is simple to operate and clear in reaction mechanism, and the modified liquid nitrile rubber has wider functional modification and application prospects and is suitable for industrial popularization.

Description

Technical Field

[0001] The invention relates to the technical field of nitrile rubber, and in particular to an amine-terminated liquid nitrile rubber and a preparation method thereof, and a silicon-containing amine-terminated liquid nitrile rubber. Background Art

[0002] Amine-terminated liquid nitrile rubber refers to a liquid nitrile polymer containing an amino group (-NH2) at the chain end, referred to as ATBN. The introduction of amino groups into liquid nitrile rubber can, on the one hand, improve the adhesion, low temperature resistance and electrical insulation properties of liquid nitrile rubber, so that liquid nitrile rubber can be used to prepare high-quality adhesives, sealing materials, anti-corrosion coatings, water-soluble electrophoretic coatings, and can be widely used in the fields of national defense, military industry, high-tech ships, etc.; on the other hand, the introduction of amino groups can also activate nitrile rubber, providing more possibilities for its performance improvement and expanding the application range of liquid nitrile rubber.

[0003] However, there is no relevant preparation technology of amine-terminated liquid nitrile rubber in China, and amine-terminated liquid nitrile rubber mainly relies on imports. Therefore, it is urgent to provide a preparation method of amine-terminated liquid nitrile rubber and silicon-containing amine-terminated liquid nitrile rubber. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of blank preparation of amine-terminated liquid nitrile rubber in China, and to provide an amine-terminated liquid nitrile rubber and a preparation method thereof, and a silicon-containing amine-terminated liquid nitrile rubber.

[0005] In order to achieve the above object, a first aspect of the present invention provides a method for preparing an amine-terminated liquid nitrile rubber, wherein the method comprises the following steps:

[0006] (1) in the presence of a catalyst, subjecting a compound containing an amino group and a hydroxyl group to an amino protecting agent for an amino protecting reaction to obtain an amino protected product;

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

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

[0009] (4) subjecting the substituted product to an amino group deprotection reaction to obtain an amine-terminated liquid nitrile rubber.

[0010] The second aspect of the present invention provides an amine-terminated liquid nitrile rubber prepared by the method described in the first aspect of the present invention.

[0011] The third aspect of the present invention provides a silicon-terminated amine-containing liquid nitrile rubber, wherein the silicon-terminated amine-containing liquid nitrile rubber is a modified carboxyl-terminated liquid nitrile rubber, and at least part of the -OH in the terminal carboxyl group in the modified carboxyl-terminated liquid nitrile rubber is substituted with a group shown in Formula 1:

[0012]

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

[0014] Through the above technical scheme, the present invention provides a method for preparing an amine-terminated liquid acrylonitrile-butadiene rubber, firstly protecting the amino group in the compound containing amino group and hydroxyl group, then using the carboxyl-terminated liquid acrylonitrile-butadiene rubber as the starting material, introducing the chlorine element through chlorination reaction, introducing the protected amino group into the liquid acrylonitrile-butadiene rubber by the substitution reaction between the chlorine element and the hydroxyl group, and then performing a deamination protection reaction on the protected amino group, thereby realizing the terminal amination of the liquid acrylonitrile-butadiene rubber. The method for preparing the amine-terminated liquid acrylonitrile-butadiene rubber provided in the present invention is simple to operate, and has a clear reaction mechanism, so that the liquid acrylonitrile-butadiene rubber has a broader functionalization modification and application prospect, and is suitable for industrial promotion.

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

[0016] The invention provides a silicon-terminated amine-containing liquid nitrile rubber, which has an amine value of 50-60 mgKOH / g, a glass transition temperature of less than -55 DEG C, and better aging resistance, ozone resistance, physiological inertness and high and low temperature resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the H NMR spectrum of the silicon-terminated amine-containing liquid nitrile rubber obtained in Example 2. DETAILED DESCRIPTION

[0018] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

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

[0020] (1) in the presence of a catalyst, subjecting a compound containing an amino group and a hydroxyl group to an amino protecting agent for an amino protecting reaction to obtain an amino protected product;

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

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

[0023] (4) subjecting the substituted product to an amino deprotection reaction with a deprotecting agent to obtain an amine-terminated liquid nitrile rubber.

[0024] In step (1):

[0025] The present invention aims to introduce an amino group (-NH2) into acrylonitrile-butadiene rubber to activate the end groups of the acrylonitrile-butadiene rubber and improve the activity of the acrylonitrile-butadiene rubber. The present invention does not specifically limit the compound 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 of the present invention 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 20 or R is a carbon skeleton containing keto, carbonyl, carboxyl, ester, cyano, aryl, silicon, siliconoxy, carbon-carbon double bond, carbon-carbon triple bond and the like on the carbon chain.

[0026] In one embodiment of the present invention, the amino- and hydroxyl-containing compounds are selected from 2-hydroxyethylamine (NH2-CH2-CH2-OH), p-hydroxyphenylethylamine 2-(3,4-Dihydroxyphenyl)ethylamine 2-Amino-1-phenylethanol One or more of the hydrolyzates of an aminosilane coupling agent.

[0027] In the present invention, the compounds containing amino groups and hydroxyl groups may be commercially available products or may be synthesized according to known methods, and the present invention does not impose any particular limitation thereto.

[0028] In one embodiment of the present invention, the aminosilane coupling agent hydrolyzate 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] Among them, in the present invention, the aminosilane coupling agent contains a siloxane group, and the siloxane group can react with water to remove the alkyl group and introduce a hydroxyl group, thereby forming a compound having both an amino group and a hydroxyl group.

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

[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, trityl compounds, formyl compounds, and trifluoroacetyl compounds, preferably tert-butyloxycarbonyl compounds, and more preferably di-tert-butyl dicarbonate.

[0032] Among them, different amino-protecting agents correspond to different reaction conditions. The present invention does not specifically limit the operating conditions of the amino-protecting reaction, and the amino-protecting reaction can be carried out by selecting known reaction conditions corresponding to different amino-protecting agents. The present invention takes the amino-protecting agent as di-tert-butyl dicarbonate as an example to illustrate the amino-protecting reaction, and other types of amino-protecting agents are not described one by one.

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

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

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

[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 compound containing amino and hydroxyl groups, the amino protecting agent and the catalyst is 1:1-2.5:0.5-2, 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 of the amino protection reaction is 10-20 hours, preferably 15-16 hours. Wherein, room temperature has a well-known meaning, for example, it can be 20-35°C.

[0039] Among them, in the present invention, the compound containing amino and hydroxyl groups and the amino protecting agent can be first dissolved in solvent I respectively, and then the solution containing the amino protecting agent is added dropwise to the solution containing the compound containing amino and hydroxyl groups at room temperature, and after the addition is completed, the reaction time is recorded.

[0040] Preferably, after the amino protection reaction is completed, the reaction solution after the amino protection reaction is subjected to reduced pressure distillation to remove the solvent I, and then water is added first and then an extractant is added to perform extraction, and the extract phase is subjected to rotary evaporation to obtain an amino protection product. Wherein, the extractant is selected from dichloromethane and / or chloroform.

[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, phosphorus oxychloride, preferably thionyl chloride.

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

[0044] In one embodiment of the present invention, the acyl chlorination reaction is carried out in a solvent II; wherein the 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 1 g of the carboxyl-terminated liquid nitrile rubber, the amount of the solvent II is 1-10 mL, preferably 2.5-5 mL.

[0046] Among them, in the present invention, in order to improve the mixing effect of the carboxyl-terminated liquid nitrile rubber and the chlorination reagent in the solvent II, it is preferred to first disperse the carboxyl-terminated liquid nitrile rubber in the solvent II, then add the chlorination reagent to the solvent II, and start the temperature reaction after treating under ultrasonic conditions for 0.5-2h.

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

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

[0049] In one embodiment of the present invention, after the acyl chlorination reaction is completed, solvent II is added again to the reaction solution after the acyl chlorination reaction, i.e., to the obtained reaction product at room temperature, and then distillation is performed, preferably under reduced pressure distillation, to remove solvent II and unreacted acyl chlorination reagent to obtain an acyl chlorination product.

[0050] In the present invention, the purpose of adding solvent II again is to dissolve the acyl chloride product generated by 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 protection 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 a solvent III; wherein the solvent III is selected from one or more of dichloromethane, chloroform, dichloroethane, and trichloroethane.

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

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

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

[0057] In one embodiment of the present invention, after the substitution reaction is completed, the reaction solution that has completed the substitution reaction, that is, the substitution reaction product, is first subjected to reduced pressure distillation to remove the solvent III, and then a purification reagent is added, followed by rotary evaporation and vacuum drying to obtain the substitution product.

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

[0059] In step (4):

[0060] Among them, in the present invention, the amino deprotection reaction is described by taking the amino protecting agent as di-tert-butyl dicarbonate as an example, and the amino deprotection reactions corresponding to other amino protecting agents can be carried out by known methods, which will not be described in detail in the present invention.

[0061] In one embodiment of the present invention, when the amino protecting agent is di-tert-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 a solvent IV, wherein the solvent IV is selected from one or more of dichloromethane, chloroform, 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 the 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] The second aspect of the present invention provides an amine-terminated liquid nitrile rubber prepared by the method described in the first aspect of the present invention.

[0066] Among them, in the amine-terminated liquid nitrile rubber prepared by the method described in the first aspect of the present invention, at least part of the -OH of the terminal carboxyl group in the carboxyl-terminated liquid nitrile rubber is replaced by an amino-containing group from a compound containing an amino group and a hydroxyl group, and the structure of the amine-terminated liquid nitrile rubber after the replacement can be as follows:

[0067] As shown in formula 1-1 to formula 1-4:

[0068]

[0069]

[0070] Wherein, in the present invention, for the convenience of description, the structural unit A, the structural unit B, the structural unit C and the end-capping group are connected together to form a complete general formula. Formulas 1-1 to 1-4 are only for schematic illustration and do not represent that the structural unit A, the structural unit B and the structural unit C are connected in the order in the general formula, wherein x, y and z are each independently selected from any integer in the range of 5-1000.

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

[0072] The third aspect of the present invention provides a silicon-terminated amine-containing liquid nitrile rubber, wherein the silicon-terminated amine-containing liquid nitrile rubber is a modified carboxyl-terminated liquid nitrile rubber, and at least part of the -OH in the terminal carboxyl group in the modified carboxyl-terminated liquid nitrile rubber is substituted with a group shown in Formula 1:

[0073]

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

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

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

[0077] In a preferred embodiment of the present invention, the general structural formula after at least part of the -OH in the terminal carboxyl groups in the modified terminal carboxyl liquid nitrile rubber is replaced by the group 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 content 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-containing liquid nitrile rubber is prepared by the method described in the first aspect of the present invention, wherein the amino- and hydroxyl-containing compound is a hydrolysis product of an aminosilane coupling agent, the amino protecting agent is di-tert-butyl dicarbonate, the acyl chloride reagent is dichlorothionyl, and the deprotecting agent is trifluoroacetic acid.

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

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

[0084] Example 1

[0085] (1) 10 mL of KH550 and 40 mL of deionized water were added to a three-necked flask equipped with a stirrer, and then the temperature was raised to 60°C and stirred for 1 h until the solution became colorless and transparent. After the reaction was completed, the solution was distilled under reduced pressure to remove the deionized water to obtain a hydrolyzate.

[0086] 5 g of the above hydrolyzate and 6 g of triethylamine were added to 30 g of methanol. After sufficient stirring, 18 g of a 30 wt% methanol solution of di-tert-butyl dicarbonate was slowly added dropwise. After the addition was complete, the reaction was carried out at room temperature for 16 h. After the reaction was completed, the methanol was distilled off under reduced pressure, the product was added to deionized water, and dichloromethane was added for extraction to obtain an extract phase. The extract phase was rotary evaporated to obtain an amino-protected product.

[0087] (2) Dissolve 2 g of carboxyl-terminated liquid nitrile rubber in 5 mL of toluene and place in a three-necked flask, then add 90 mL of thionyl chloride, and ultrasonicate for 1 h. Then, heat to 70 °C for acyl chloride reaction and react for 13 h under nitrogen protection. After the reaction is completed, cool to room temperature, add 90 mL of toluene, and remove toluene and unreacted thionyl chloride by vacuum distillation to obtain an acyl chloride product.

[0088] (3) Dissolve 1 g of the above acyl chloride product in 5 g of dichloromethane, slowly add 1.5 g of the above amino protection product dropwise at 0°C, and after the addition is completed, react with magnetic stirring at room temperature for 10 h. After the reaction is completed, perform vacuum distillation to remove dichloromethane, then add 12.5 g of n-hexane for purification, and obtain the substituted product by rotary evaporation and vacuum drying.

[0089] (4) 1 g of the above-mentioned substituted product was dissolved in 7 g of dichloromethane, and 2.3 g of 25 wt% TFA solution was added. The mixture was reacted at room temperature for 0.5 h. After the reaction was completed, the liquid nitrile rubber containing silicon-terminated amine groups was obtained by rotary evaporation and vacuum drying.

[0090] Wherein, the reaction equation occurring in each step in Example 1 is as follows:

[0091] Step (1)

[0092]

[0093] Step (2)

[0094] Step (3)

[0095] Step (4)

[0096] Example 2

[0097] (1) 10 mL of KH550 and 35 mL of deionized water were added to a three-necked flask equipped with a stirrer, and then the temperature was raised to 50°C and stirred for 1.5 h until the solution became colorless and transparent. After the reaction was completed, the solution was distilled under reduced pressure to remove the deionized water to obtain a hydrolyzate.

[0098] 5 g of the above hydrolyzate and 5 g of triethylamine were added to 30 g of methanol. After sufficient stirring, 20 g of a 30 wt% methanol solution of di-tert-butyl dicarbonate was slowly added dropwise. After the addition was complete, the reaction was carried out at room temperature for 16 h. After the reaction was completed, the methanol was distilled off under reduced pressure, the product was added to deionized water, and dichloromethane was added for extraction to obtain an extract phase. The extract phase was rotary evaporated to obtain an amino-protected product.

[0099] (2) Dissolve 2 g of carboxyl-terminated liquid nitrile rubber in 5 mL of toluene and place in a three-necked flask, then add 100 mL of thionyl chloride, and ultrasonicate for 1 h. Then, heat to 80 °C for acyl chloride reaction and react for 14 h under nitrogen protection. After the reaction is completed, cool to room temperature, add 100 mL of toluene, and remove toluene and unreacted thionyl chloride by vacuum distillation to obtain an acyl chloride product.

[0100] (3) Dissolve 1 g of the above acyl chloride product in 5 g of dichloromethane, slowly add 2 g of the above amino protection product at 3°C, and after the addition is completed, react with magnetic stirring at room temperature for 12 h. After the reaction is completed, perform vacuum distillation to remove dichloromethane, then add 12.5 g of n-hexane for purification, and obtain the substitution product by rotary evaporation and vacuum drying.

[0101] (4) 1 g of the above-mentioned substituted product was dissolved in 7 g of dichloromethane, and 2.0 g of 25 wt% TFA solution was added, and the mixture was reacted at room temperature for 1 h. After the reaction was completed, the liquid nitrile rubber containing silicon-terminated amine groups was obtained by rotary evaporation and vacuum drying.

[0102] Example 3

[0103] (1) 10 mL of KH550 and 20 mL of deionized water were added to a three-necked flask equipped with a stirrer, and then the temperature was raised to 40°C and stirred for 2 h until the solution became colorless and transparent. After the reaction was completed, the solution was distilled under reduced pressure to remove the deionized water to obtain a hydrolyzate.

[0104] The above 5g of hydrolyzate and 3g of triethylamine were added to 30g of methanol. After sufficient stirring, 30g of 30wt% methanol solution of di-tert-butyl dicarbonate was slowly added dropwise. After the addition was completed, the reaction was carried out at room temperature for 18h. After the reaction was completed, the methanol was distilled off under reduced pressure, the product was added to deionized water, and dichloromethane was added for extraction to obtain an extract phase, and the extract phase was rotary evaporated to obtain an amino-protected product.

[0105] (2) Dissolve 2 g of carboxyl-terminated liquid nitrile rubber in 5 mL of toluene and place in a three-necked flask, then add 120 mL of thionyl chloride, and ultrasonicate for 1 h. Then, heat to 65 °C for acyl chloride reaction and react for 18 h under nitrogen protection. After the reaction is completed, cool to room temperature, add 120 mL of toluene, and remove toluene and unreacted thionyl chloride by vacuum distillation to obtain an acyl chloride product.

[0106] (3) Dissolve 1 g of the above acyl chloride product in 5 g of dichloromethane, slowly add 1 g of the above amino protection product dropwise at 5°C, and after the addition is completed, react with magnetic stirring at room temperature for 6 h. After the reaction is completed, perform vacuum distillation to remove dichloromethane, then add 12.5 g of n-hexane for purification, and obtain the substituted product by rotary evaporation and vacuum drying.

[0107] (4) 1 g of the above-mentioned substituted product was dissolved in 7 g of dichloromethane, and 1.5 g of 25 wt% TFA solution was added, and the mixture was reacted at room temperature for 1 h. After the reaction was completed, the liquid nitrile rubber containing silicon-terminated amine groups was obtained by rotary evaporation and vacuum drying.

[0108] Example 4

[0109] (1) 10 mL of KH550 and 60 mL of deionized water were added to a three-necked flask equipped with a stirrer, and then the temperature was raised to 75°C and stirred for 0.5 h until the solution became colorless and transparent. After the reaction was completed, the solution was distilled under reduced pressure to remove the deionized water to obtain a hydrolyzate.

[0110] 5 g of the above hydrolyzate and 8 g of triethylamine were added to 30 g of methanol. After sufficient stirring, 35 g of a 30 wt% methanol solution of di-tert-butyl dicarbonate was slowly dripped. After the addition was completed, the reaction was carried out at room temperature for 12 hours. After the reaction was completed, the methanol was removed by distillation under reduced pressure. The product was added to deionized water, and dichloromethane was added for extraction to obtain an extract phase. The extract phase was rotary evaporated to obtain an amino-protected product.

[0111] (2) Dissolve 2 g of carboxyl-terminated liquid nitrile rubber in 5 mL of toluene and place in a three-necked flask, then add 60 mL of thionyl chloride, and ultrasonicate for 1 h. Then, heat to 85 °C for acyl chloride reaction and react for 10 h under nitrogen protection. After the reaction is completed, cool to room temperature, add 60 mL of toluene, and remove toluene and unreacted thionyl chloride by vacuum distillation to obtain an acyl chloride product.

[0112] (3) Dissolve 1 g of the above acyl chloride product in 5 g of dichloromethane, slowly add 2.5 g of the above amino protection product at 0°C, and after the addition is completed, react with magnetic stirring at room temperature for 14 h. After the reaction is completed, perform vacuum distillation to remove dichloromethane, then add 12.5 g of n-hexane for purification, and obtain the substituted product by rotary evaporation and vacuum drying.

[0113] (4) 1 g of the above-mentioned substituted product was dissolved in 7 g of dichloromethane, and 3.0 g of 25% TFA solution was added. The mixture was reacted at room temperature for 1.5 h. After the reaction was completed, the liquid nitrile rubber containing silicon-terminated amine groups was obtained by rotary evaporation and vacuum drying.

[0114] Example 5

[0115] The same as Example 4, except that the hydrolysis in step (1) is omitted and the hydrolyzate is replaced by an equal amount of 2-hydroxyethylamine.

[0116] Among them, in the obtained amine-terminated liquid nitrile rubber, the general structural formula after at least part of the -OH in the terminal carboxyl group in the carboxyl-terminated liquid nitrile rubber is replaced by a group containing an amino group is as follows:

[0117]

[0118] Example 6

[0119] The same as Example 4, except that the hydrolysis in step (1) is omitted and the hydrolysis product is replaced by p-hydroxyphenylethylamine in an equal amount.

[0120] Among them, in the obtained amine-terminated liquid nitrile rubber, the general structural formula after at least part of the -OH in the terminal carboxyl group in the carboxyl-terminated liquid nitrile rubber is replaced by a group containing an amino group is as follows:

[0121]

[0122] Example 7

[0123] The same as Example 4, except that the hydrolysis in step (1) is omitted and the hydrolyzate is replaced by an equal amount of 2-amino-1-phenylethanol.

[0124] Among them, in the obtained amine-terminated liquid nitrile rubber, the general structural formula after at least part of the -OH in the terminal carboxyl group in the carboxyl-terminated liquid nitrile rubber is replaced by a group containing an amino group is as follows:

[0125]

[0126] Test Example 1

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

[0128] from Figure 1 The nuclear magnetic hydrogen spectrum of the modified liquid nitrile rubber shows: 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-containing liquid nitrile rubber was successfully prepared.

[0129] Test Example 2

[0130] The corresponding properties of the amine-terminated liquid nitrile rubber prepared in Examples 1-7 were measured, and the test results are shown in Table 1.

[0131] The viscosity is measured using a rotational viscosity viscometer, the free amine value is measured in accordance with GB / T6365-2006, and the glass transition temperature is measured in accordance with GB / T 29611-2013.

[0132] The carboxyl conversion rate is determined by acid-base titration, specifically as follows: soak the same mass of raw material carboxyl-terminated liquid nitrile rubber and the prepared amine-terminated liquid nitrile rubber in 0.5% HCl for 30 minutes, filter out, wash with deionized water for many times, dry, then take 1g of sample respectively, immerse in an iodine volume flask containing 250mL of 0.1M calcium acetate solution, place in an oscillator for 24 hours, draw 10mL of test solution into a conical flask, use cresol red and thymol blue as indicators, titrate with 0.1mol / L NaOH solution, and calculate the content after the titration from yellow to purple rose. Among them, the molar content of carboxyl in the raw material carboxyl-terminated liquid nitrile rubber is n1, the molar content of carboxyl in the prepared amine-terminated liquid nitrile rubber is n2, and the carboxyl conversion rate is equal to (n1-n2) / n1.

[0133] The amine value is determined by 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 amine-terminated liquid nitrile rubber prepared in Examples 1-7 is above 75%, and the amine value is between 40-60 mgKOH / g, and the free amine is <4%, which indicates that the liquid nitrile rubber containing amino groups at the end groups is successfully prepared.

[0138] The viscosity of the amine-terminated liquid nitrile rubber prepared in Examples 1-7 is in the range of 170-240 Pa·s, the number average molecular weight is in the range of 3500-4500 g / mol, and the glass transition temperature is less than -45°C, indicating that the amine-terminated liquid nitrile rubber has good fluidity and low temperature resistance, and has a broader modification and application space.

[0139] The performance of the liquid nitrile rubber containing silicon-terminated amine groups in Examples 1-4 is relatively good, and the glass transition temperature is less than -55°C. This is because the introduction of the silane-containing structure further improves the performance of the liquid nitrile rubber.

[0140] Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any appropriate manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

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

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

3. The preparation method according to claim 2, wherein The aminosilane coupling agent hydrolyzate is obtained by hydrolyzing 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 tert-butyloxycarbonyl compounds, benzyloxycarboxyl compounds, 2-biphenyl-2-propoxycarbonyl compounds, phthalimide compounds, trityl 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 di-tert-butyl dicarbonate.

7. The preparation method according to claim 6, wherein: When the amino protecting agent is di-tert-butyl dicarbonate, the operating conditions of the amino protecting reaction include: The amino protection reaction is carried out in solvent I; wherein the 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 hours.

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 of the amino protection reaction is 15-16 hours.

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 usage ratio of the carboxyl-terminated liquid nitrile rubber to the acyl chloride reagent is 1 g: 30-70 mL.

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

11. The preparation method according to claim 1, wherein: The acyl chlorination reaction is carried out in a solvent II; wherein the solvent II is selected from one or more of toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene; And / or, the acyl chlorination reaction is carried out under the protection of an inert gas; And / or, the reaction temperature of the acyl chlorination reaction is 60-90°C, and the reaction time of the acyl chlorination reaction is 8-20h; And / or, after the acyl chlorination reaction is completed, the solvent II is added again to the obtained reaction product at room temperature and then distilled to remove the solvent II and unreacted acyl chlorination reagent to obtain the acyl chlorination product.

12. The preparation method according to claim 11, wherein The inert gas is nitrogen; And / or, the reaction temperature of the acyl chlorination reaction is 70-80°C, and the reaction time of the acyl chlorination reaction is 12-15h; And / or, the distillation is a reduced pressure distillation.

13. The preparation method according to claim 1, wherein: The mass ratio of the acyl chloride product to the amino protection product is 1:1-2.5; And / or, the substitution reaction is carried out in a solvent III; wherein the solvent III is selected from one or more of dichloromethane, chloroform, dichloroethane, and trichloroethane; And / or, the substitution reaction process comprises: first dissolving the acyl chloride product in the solvent III, then dropwise adding the amino protection product, and then reacting at room temperature for 6-18 hours; And / or, the dropping is carried out at 0-10°C; And / or, after the substitution reaction is completed, the obtained substitution reaction product is first subjected to reduced pressure distillation to remove the solvent III, and then a purification reagent is added, followed by rotary evaporation and vacuum drying to obtain a substitution product; And / or, the purification reagent is one or more of n-hexane, n-heptane, and n-octane, and the added amount of the purification reagent is 10-20 g based on 1 g of the amino-protected product.

14. The preparation method according to claim 13, wherein: The mass ratio of the acyl chloride product to the amino protection product is 1:1.5-2; And / or, the substitution reaction time is 8-12h; And / or, the dropping temperature is 0-5°C.

15. The preparation method according to claim 1, wherein: The deprotecting agent is selected from trifluoroacetic acid and / or dioxane hydrochloride solution; And / or, the deamination protection reaction is carried out in a solvent IV, wherein the solvent IV is selected from one or more of dichloromethane, chloroform, dichloroethane, trichloroethane, and dimethylformamide; and / or, the mass ratio of the substituted 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 0.2-2.5h.

16. The preparation method according to claim 15, wherein: The deprotecting agent is trifluoroacetic acid; and / or, the mass ratio of the substituted 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 0.5-1h.

17. An amine-terminated liquid nitrile rubber prepared by the method according to any one of claims 1 to 16.

18. A liquid nitrile rubber containing silicon-terminated amine groups, characterized in that: The silicon-terminated amine-containing liquid nitrile rubber is a modified carboxyl-terminated liquid nitrile rubber, wherein at least part of the -OH of the carboxyl-terminated group in the modified carboxyl-terminated liquid nitrile rubber is replaced by a group shown in Formula 1: Wherein, R1 and R2 are each independently selected from hydroxyl and / or alkyl, and R3 is selected from alkylene.

19. The silicon-terminated amine-containing liquid nitrile rubber according to claim 18, wherein The alkyl group is selected from a linear or branched C1-C5 alkyl group, and the alkylene group is selected from a linear or branched C1-C5 alkylene group.

20. The silicon-terminated amine-containing liquid nitrile rubber according to claim 19, wherein: The alkyl group is selected from methyl, ethyl and n-propyl, and the alkylene group is selected from methylene, ethylene, propylene and butylene.

21. The silicon-terminated amine-containing liquid nitrile rubber according to any one of claims 18 to 20, wherein: The amine value of the amine-terminated liquid nitrile rubber is 50-60 mgKOH / g, preferably 55-58 mgKOH / g.

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