Amino-terminated liquid nitrile rubber, its preparation method and application

Abstract

The application discloses an amino-terminated liquid nitrile rubber and a preparation method and application thereof, and the preparation method comprises the following steps: reacting carboxyl-terminated liquid nitrile rubber, an organic solvent, an acid catalyst and an acyl halide reagent to form an intermediate acyl chloride derivative; and then reacting the acyl chloride derivative with an amine organic compound to obtain the amino-terminated liquid nitrile rubber. The amino-terminated liquid nitrile rubber has a proper amino value, can participate in a crosslinking reaction, is beneficial to the performance improvement in a material processing process, can effectively balance the chemical reactivity, processability and material performance, and exhibits better comprehensive performance. In addition, the amino-terminated liquid nitrile rubber has a proper gel content and non-volatile content, has a higher purity, meets the use requirement in a production and processing process, and exhibits better processability. The preparation process of the application has simple steps, low operation strength, high product yield, low production cost, and is easy to realize industrial control and continuous production.

Description

Technical Field

[0001] This invention belongs to the field of polymer synthesis and relates to an amino-terminated liquid butadiene-nitrile rubber, its preparation method, and its application. Background Technology

[0002] Liquid nitrile rubber (NBR) is a type of synthetic rubber with good elasticity, oil resistance, chemical corrosion resistance, and strong adhesion. Its main component is nitrile rubber, obtained by copolymerizing butadiene and acrylonitrile. Compared to traditional solid NBR, liquid NBR has higher fluidity and can be processed at room temperature through impregnation, coating, and injection molding. It is often blended with hard resins such as epoxy resins and phenolic resins to enhance the impact toughness and mechanical strength of composite materials. Simultaneously, liquid NBR can also be used as an oil-resistant and wear-resistant material in the automotive, hydraulic sealing, and oil seal industries. Furthermore, it is used in seals, adhesives, coatings, and water-based adhesives, and is widely applied in the automotive, aerospace, electronics, and chemical industries.

[0003] The molecular chains of liquid nitrile rubber (NBR) typically end with carboxyl groups (-COOH), resulting in weak interactions and slightly poor physical compatibility when blended with other polymers or resins. Therefore, in practical applications, liquid NBR suffers from poor heat resistance, insufficient impact strength, and inadequate toughening. Modifying NBR by introducing amino (-NH2) groups at its ends yields amino-terminated liquid NBR, which increases its chemical reactivity with other materials, thereby enhancing its properties. Amino-terminated liquid NBR not only inherits the excellent elasticity, oil resistance, and flowability of traditional liquid NBR but also significantly enhances its adhesive properties, heat resistance, toughening, and processing performance through the introduction of amino groups. This overcomes the shortcomings of traditional liquid NBR in high-temperature environments, impact strength, and processing performance, and thus it is widely used in epoxy resin plasticizing, adhesives, sealants, and other fields.

[0004] However, existing methods for preparing amine-terminated liquid nitrile butadiene rubber are often limited by the synthesis methods and material structures, resulting in problems such as complex operation, cumbersome steps, difficulty in controlling reaction conditions, and unstable product properties. Therefore, improving the production efficiency and product performance of amine-terminated liquid nitrile butadiene rubber has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an amino-terminated liquid nitrile rubber with a suitable amino value, or the ability to participate in crosslinking reactions to improve performance during material processing, or the ability to effectively balance chemical reactivity, processability, and material properties to exhibit better overall performance; in addition, it also has a suitable gel content and non-volatile content, as well as high purity, to meet the requirements for use in the production and processing process and exhibit better processing performance.

[0006] This invention also provides a method for preparing amino-terminated liquid nitrile butadiene rubber with high yield, high purity, and low cost. Using carboxyl-terminated liquid nitrile butadiene rubber as the starting material, the method involves reacting it with an acid catalyst and an acyl halide reagent to obtain an acyl chloride derivative, which is then reacted with an amine organic compound to finally obtain the amino-terminated liquid nitrile butadiene rubber. The preparation method of this invention is simple, has mild reaction conditions, and achieves high yield. This method effectively improves the reaction efficiency and product purity of amino-terminated liquid nitrile butadiene rubber while reducing production costs.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] An amino-terminated liquid nitrile rubber, wherein the amino value of the amino-terminated liquid nitrile rubber is 20KOH mg / g to 8090KOH mg / g, and the acrylonitrile content is 10% to 70%.

[0009] The amino value of the terminal amino liquid nitrile rubber of the present invention is 20 KOH mg / g to 80-90 KOH mg / g. At this value, the amino groups can participate in the crosslinking reaction, which is beneficial to the performance improvement during the material processing.

[0010] In some embodiments of the present invention, the amino value of the terminal amino liquid nitrile rubber is 45 KOH mg / g to 80 KOH mg / g, preferably 55 KOH mg / g to 70 KOH mg / g. Studies have found that when the amino value is within this range, chemical reactivity, processability, and material properties can be effectively balanced, exhibiting better overall performance.

[0011] The acrylonitrile content of the terminal amino liquid nitrile rubber of the present invention is 10% to 70%, which provides good oil resistance, abrasion resistance and chemical stability, while maintaining appropriate flexibility and processability.

[0012] In some embodiments of the present invention, the acrylonitrile content of the amino-terminated liquid nitrile rubber is 12% to 45%, preferably 15% to 35%. Amino-terminated liquid nitrile rubber within this range exhibits relatively balanced physical properties and is suitable for a wider range of applications.

[0013] In some embodiments of the present invention, the gel content of the terminal amino liquid nitrile rubber is <1%, preferably ≤0.85%, and more preferably ≤0.65%.

[0014] In some embodiments of the present invention, the non-volatile content of the terminal amino liquid nitrile rubber is ≥97%, preferably ≥98.5%, and more preferably ≥99%.

[0015] The terminal amino liquid nitrile rubber gel of the present invention has a low content of non-volatile matter, high product purity, and exhibits better processing performance, meeting the usage requirements in the production and processing process.

[0016] In some embodiments of the present invention, the amino-terminated liquid nitrile rubber is prepared from carboxyl-terminated liquid nitrile rubber.

[0017] In some embodiments of the present invention, the amino-terminated liquid nitrile rubber is prepared by first preparing an acyl chloride derivative under the action of an acid catalyst, and then reacting it with an amine organic compound.

[0018] This invention also provides a method for preparing amino-terminated liquid nitrile rubber, the preparation method comprising the following steps:

[0019] Step 1: Mix terminal carboxyl liquid nitrile rubber with an organic solvent, add an acid catalyst and an acyl halide reagent to react and obtain an acyl chloride derivative;

[0020] Step 2: Mix the acyl chloride derivative with an organic solvent, add an amine organic compound to react, and obtain an amino-terminated liquid nitrile rubber.

[0021] According to an embodiment of the present invention, step two further includes solvent removal and drying purification of the obtained amino-terminated liquid nitrile rubber.

[0022] According to an embodiment of the present invention, the carboxyl-terminated liquid nitrile rubber is a polymer in which acrylic acid or methacrylic acid monomers are added during the polymerization of butadiene and acrylonitrile. The carboxyl-terminated liquid nitrile rubber used in this invention contains carboxyl (-COOH) functional groups at the ends of its molecular chains. The introduction of these carboxyl groups gives it better reactivity than ordinary liquid nitrile rubber, which helps improve the interfacial properties of the composite material, enhances its impact strength and flexibility, and also provides good chemical resistance and abrasion resistance.

[0023] According to an embodiment of the present invention, the carboxyl-terminated liquid nitrile rubber has a Bruker viscosity of 500 cps to 700,000 cps, an acrylonitrile content of 10% to 70%, and a polymer backbone containing carbon-carbon double bonds.

[0024] Preferably, the carboxyl-terminated liquid nitrile butadiene rubber has a Bruker viscosity of 50,000 cps-400,000 cps and an acrylonitrile content of 12%-40%. Within this range, the carboxyl-terminated liquid nitrile butadiene rubber exhibits good flowability, which is more conducive to compounding and processing, and provides better mechanical properties when blended. It can effectively improve the impact toughness of the material when blended with other polymers (especially hard resins such as epoxy resins and phenolic resins).

[0025] According to an embodiment of the present invention, the organic solvent is one of dichloromethane, butanone, toluene, xylene, a complex of anhydrous ethanol and xylene, a complex of anhydrous ethanol and butanone, and a complex of anhydrous ethanol and tetrahydrofuran.

[0026] According to an embodiment of the present invention, the acid catalyst is one of N,N-dimethylformamide, 4-dimethyl-terminated aminopyridine, and p-toluenesulfonic acid.

[0027] According to an embodiment of the present invention, the acyl halide reagent is one of formyl chloride, acetyl chloride, benzoyl chloride, oxalyl chloride, chloroacetyl chloride, and trichloroacetyl chloride.

[0028] According to an embodiment of the present invention, the amine organic compound is one of N-methyl-1,3-propanediamine, 3-terminal amino-1,2,4-triazole, 4,4'-trimethylenedipiperidine, 4-(terminal aminomethyl)piperidine, piperazine, N-(2-aminoethyl)piperazine, and N-(3-terminal aminopropyl)piperazine.

[0029] According to an embodiment of the present invention, in step one, the reaction temperature is -80℃ to 30℃, preferably -30℃ to 0℃, and exemplarily -30℃, -10℃ or 0℃; the reaction time is 3h to 20h, preferably 3h to 18h, more preferably 3h to 8h, and exemplarily 3h, 4h, 6h, 8h, 10h, 12h, 15h, 18h or 20h.

[0030] According to an embodiment of the present invention, in step one, the mixing is carried out under stirring. For example, the stirring temperature is -10℃ to 10℃, exemplarily 0℃; the stirring time is 10min to 30min, exemplarily 10min, 20min or 30min.

[0031] According to an embodiment of the present invention, in step two, the reaction temperature is -80℃ to 30℃, preferably -20℃ to 0℃, and exemplarily -30℃, -10℃ or 0℃; the reaction time is 4h to 18h, preferably 4h to 10h, and exemplarily 3h, 4h, 6h, 8h, 10h, 12h, 15h or 18h.

[0032] According to an embodiment of the present invention, in step two, the mixing is carried out under stirring. For example, the stirring temperature is -10℃ to 10℃, exemplarily 0℃; the stirring time is 20min to 60min, exemplarily 20min, 30min, 40min, 50min or 60min.

[0033] According to an embodiment of the present invention, the preparation method of the amino-terminated liquid nitrile rubber includes the following steps:

[0034] Step 1: Dissolve the carboxyl-terminated liquid nitrile rubber in an organic solvent; stir under a nitrogen atmosphere for 10-30 minutes, add an acid catalyst and acyl halide reagent, and react for 3-8 hours to obtain an acyl chloride derivative; remove the solvent from the acyl chloride derivative.

[0035] Step 2: Dissolve the acyl chloride derivative obtained in Step 1 in an organic solvent, stir under a nitrogen atmosphere for 20 min to 60 min, add an amine organic compound and react for 4 h to 10 h to obtain a crude product of amino reaction. Extract and dry the crude product of amino reaction to obtain terminal amino liquid nitrile rubber.

[0036] In some embodiments of the present invention, the equivalent ratio of the carboxyl-terminated liquid nitrile rubber to the acid catalyst is 1:(0.05-0.5), preferably 1:(0.1-0.2), and exemplary ratios are 1:0.05, 1:0.1, 1:0.2 or 1:0.5.

[0037] In some embodiments of the present invention, the equivalent ratio of the carboxyl-terminated liquid nitrile rubber to the acyl halide reagent is 1:(2-4), preferably 1:(3-4), and exemplary ratios are 1:2, 1:3 or 1:4.

[0038] In some embodiments of the present invention, the equivalent ratio of the carboxyl-terminated liquid nitrile rubber to the amine organic compound is 1:(1-5), preferably 1:(2-4), and exemplary ratios are 1:1, 1:2, 1:3, 1:4 or 1:5.

[0039] The amino-terminated liquid nitrile rubber of the present invention is prepared by the above-described method for preparing amino-terminated liquid nitrile rubber.

[0040] The present invention also provides the application of the above-mentioned amino-terminated liquid nitrile rubber in the fields of epoxy resin plasticizers, adhesives, sealants, etc.

[0041] The present invention also provides a composite material containing the above-mentioned amino-terminated liquid nitrile rubber and / or prepared from the above-mentioned amino-terminated liquid nitrile rubber.

[0042] According to an embodiment of the present invention, the composite material can be an adhesive or a sealant.

[0043] The present invention also provides a method for plasticizing epoxy resin, comprising reacting the above-mentioned amino-terminated liquid nitrile rubber with epoxy resin.

[0044] Beneficial effects of the present invention

[0045] This invention provides an amino-terminated liquid nitrile rubber with a suitable amino value, which can either participate in crosslinking reactions to improve the performance of the material during processing, or effectively balance chemical reactivity, processability, and material properties to exhibit better overall performance; in addition, it also has a suitable gel content and non-volatile content as well as high purity, meeting the requirements for use in the production and processing process and exhibiting better processing performance.

[0046] This invention also provides a method for preparing the aforementioned amino-terminated liquid nitrile butadiene rubber. The amino-terminated liquid nitrile butadiene rubber prepared by this method has highly reactive amino groups, which can undergo crosslinking or toughening reactions with other chemical substances (such as epoxy resins, polyesters, phenolic resins, etc.) in subsequent processing, thereby improving the mechanical properties, thermal stability, and aging resistance of the rubber. Compared with existing methods for preparing amino-terminated liquid nitrile butadiene rubber, the preparation method of this invention has mild reaction conditions, is simple to operate, and has a high conversion rate of carboxyl-terminated liquid nitrile butadiene rubber. The amino-terminated liquid nitrile butadiene rubber prepared in this way has good stability and low gel content. The amino-terminated liquid nitrile butadiene rubber obtained by this invention has excellent elasticity, adhesion properties, and chemical resistance, and can be widely used in epoxy resin plasticizing, adhesives, sealants, and other fields.

[0047] The method for preparing terminal amino liquid nitrile butadiene rubber of the present invention can effectively overcome the shortcomings of the prior art, simplify the reaction process, improve the degree of terminal aminoization and molecular weight control of the product, and achieve good processability and reactivity. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of FT-IR of terminal carboxyl group liquid nitrile rubber.

[0049] Figure 2 This is an FT-IR schematic diagram of the amino-terminated liquid nitrile rubber prepared in Example 4. Detailed Implementation

[0050] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0051] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0052] Example 1

[0053] A method for preparing amino-terminated liquid nitrile butadiene rubber, comprising the following steps:

[0054] Step 1: Dissolve 5.00 g (1 equiv) of carboxyl-terminated liquid nitrile rubber (purchased from Zibo Qilong Chemical Co., Ltd.) in 100 ml of dichloromethane; stir for 10 min at 0 °C under a nitrogen atmosphere, add N,N-dimethylformamide (0.1 equiv) and oxalyl chloride solvent (2 equiv), and react at -10 °C for 4 h to obtain an acyl chloride derivative; remove the solvent by rotary evaporation of the acyl chloride derivative.

[0055] Step 2: The acyl chloride derivative obtained in the above steps is fully dissolved in 100 ml of dichloromethane solvent, and stirred at 0 °C for 15 min under a nitrogen atmosphere. N-(2-aminoethyl)piperazine (3 equiv) is added, and the mixture is reacted at -10 °C for 6 h to obtain the crude product of the amino reaction. The crude product of the amino reaction is extracted with anhydrous ethanol and then vacuum dried to obtain terminal amino liquid nitrile rubber.

[0056] The equivalent ratios of the test raw materials used in Example 1 and the carboxyl-terminated liquid nitrile rubber to N,N-dimethylformamide, oxaloyl chloride solvent, and N-(2-aminoethyl)piperazine are shown in Table 1.

[0057] Examples 2-5

[0058] The preparation methods of Examples 2-5 are the same as those of Example 1, except that the equivalent ratio of terminal carboxyl liquid nitrile rubber (1 equiv) to acid catalyst, oxaloyl chloride, and N-(2-aminoethyl)piperazine is changed.

[0059] The equivalent ratios of the test raw materials and carboxyl-terminated liquid nitrile rubber used in Examples 2-5 to N,N-dimethylformamide, oxaloyl chloride solvent, and N-(2-aminoethyl)piperazine are shown in Table 1.

[0060] Example 6

[0061] A method for preparing amino-terminated liquid nitrile butadiene rubber, comprising the following steps:

[0062] Step 1: Dissolve 10.00 g (1 equiv, purchased from Zibo Qilong Chemical Co., Ltd.) of carboxyl-terminated liquid nitrile rubber in 100 ml xylene; stir for 20 min under nitrogen atmosphere at 0 °C, add N,N-dimethylformamide (0.1 equiv) and oxalyl chloride solvent (2 equiv), and react at -10 °C for 6 h to obtain acyl chloride derivative; remove solvent by rotary evaporation of acyl chloride derivative.

[0063] Step 2: After fully dissolving the acyl chloride derivative obtained in the above steps in xylene solvent, stir for 30 min at 0°C under a nitrogen atmosphere, add N-(2-aminoethyl)piperazine (3 equiv), and react at -10°C for 8 h to obtain the crude product of the amino reaction. Extract with anhydrous ethanol and vacuum dry the crude product of the amino reaction to obtain terminal amino liquid nitrile rubber.

[0064] The equivalent ratios of the test raw materials used in Example 6 and the carboxyl-terminated liquid nitrile rubber to N,N-dimethylformamide, oxaloyl chloride solvent, and N-(2-aminoethyl)piperazine are shown in Table 1.

[0065] Example 7

[0066] A method for preparing amino-terminated liquid nitrile butadiene rubber, comprising the following steps:

[0067] Step 1: Dissolve 10.00 g (1 equiv, purchased from Zibo Qilong Chemical Co., Ltd.) of carboxyl-terminated liquid nitrile rubber in 100 ml xylene; stir for 30 min under nitrogen atmosphere at 0 °C, add N,N-dimethylformamide (0.1 equiv) and oxalyl chloride solvent (2 equiv), and react at -30 °C for 10 h to obtain acyl chloride derivative; remove solvent by rotary evaporation of acyl chloride derivative.

[0068] Step 2: After fully dissolving the acyl chloride derivative obtained in the above steps in xylene solvent, stir for 30 min at 0°C under a nitrogen atmosphere, add N-(2-aminoethyl)piperazine (3 equiv), and react at -30°C for 12 h to obtain the crude product of the amino reaction. Extract with anhydrous ethanol and vacuum dry the crude product of the amino reaction to obtain terminal amino liquid nitrile rubber.

[0069] The equivalent ratios of the test raw materials used in Example 7 and the carboxyl-terminated liquid nitrile rubber to N,N-dimethylformamide, oxaloyl chloride solvent, and N-(2-aminoethyl)piperazine are shown in Table 1.

[0070] Example 8

[0071] A method for preparing amino-terminated liquid nitrile butadiene rubber, comprising the following steps:

[0072] Step 1: Dissolve 10.00 g (1 equiv, purchased from Zibo Qilong Chemical Co., Ltd.) of carboxyl-terminated liquid nitrile rubber in 100 ml xylene; stir for 20 min under nitrogen atmosphere at 0 °C, add N,N-dimethylformamide (0.1 equiv) and oxalyl chloride solvent (3 equiv), and react at -30 °C for 6 h to obtain acyl chloride derivative; remove solvent by rotary evaporation of acyl chloride derivative.

[0073] Step 2: After fully dissolving the acyl chloride derivative obtained in the above steps in xylene solvent, stir for 20 min at 0°C under a nitrogen atmosphere, add N-(2-aminoethyl)piperazine (2 equiv), and react at -30°C for 8 h to obtain the crude product of the amino reaction. Extract with anhydrous ethanol and vacuum dry the crude product of the amino reaction to obtain terminal amino liquid nitrile rubber.

[0074] The equivalent ratios of the test raw materials and carboxyl-terminated liquid nitrile rubber used in Example 8 to N,N-dimethylformamide, oxaloyl chloride solvent, and N-(2-aminoethyl)piperazine are shown in Table 1.

[0075] Examples 9-10

[0076] The preparation methods of Examples 9 and 10 are the same as those of Example 6, except that the equivalent ratio of terminal carboxyl liquid nitrile rubber (1 equiv) to acid catalyst, oxaloyl chloride, and N-(2-aminoethyl)piperazine is changed.

[0077] The equivalent ratios of the test raw materials and carboxyl-terminated liquid nitrile rubber to N,N-dimethylformamide, oxaloyl chloride solvent, and N-(2-aminoethyl)piperazine used in Examples 9-10 are shown in Table 1.

[0078] Comparative Examples 1-3

[0079] The preparation methods of Comparative Examples 1-3 are the same as those of Example 1, except that the equivalent ratio of terminal carboxyl liquid nitrile rubber (1 equiv) to acid catalyst, oxaloyl chloride, and N-(2-aminoethyl)piperazine is changed.

[0080] The equivalent ratios of the test materials used in Comparative Examples 1-3 and the carboxyl-terminated liquid nitrile rubber to N,N-dimethylformamide, oxaloyl chloride solvent, and N-(2-aminoethyl)piperazine are shown in Table 1.

[0081] Table 1 Reaction conditions of Examples 1-10 and Comparative Examples 1-3

[0082]

[0083] The performance indicators of the final products of Examples 1-10 and Comparative Examples 1-3 are shown in Table 2. Wherein:

[0084] The test for acrylonitrile content in amino-terminated liquid nitrile rubber shall be performed in accordance with SH / T 1503-2014.

[0085] The determination method is as follows: After sample processing, the sample is digested by heating with sulfuric acid under the action of a catalyst to convert the nitrogen in the bound acrylonitrile into ammonium bisulfate. Excess sodium hydroxide solution is added and distilled. The released ammonia is absorbed by boric acid solution, and the absorbent is titrated with sulfuric acid standard titration solution. The content of bound acrylonitrile is calculated based on the titration results.

[0086] The nonvolatile content of amino-terminated liquid nitrile rubber was determined using a rapid moisture analyzer.

[0087] The determination method is as follows: The instrument is calibrated to zero, the heating temperature is set to 140℃, 1g of liquid sample is taken using a microsyringe and evenly added to the sample pan, the heating program is started, and after drying, the instrument automatically cools down and calculates the non-volatile content. Three parallel tests are performed; if the deviation is <1%, the average value is taken to obtain the non-volatile content.

[0088] The gel content of the amino-terminated liquid nitrile rubber shall comply with SHT 1050-2014.

[0089] The determination method is as follows: after cutting the rubber sample into small pieces, immerse it in toluene solvent and let it stand to dissolve. The insoluble gel remains on a stainless steel filter screen with a pore size of 125 μm. The mass percentage of the gel relative to the initial sample is calculated by drying and weighing the residue.

[0090] The amine value of terminal amino liquid nitrile rubber refers to the number of amino groups in the molecule, that is, the amount of acid required to titrate 1g of basic amine, expressed as milligrams of potassium hydroxide (KOH) per g.

[0091] The determination method is as follows: Weigh 0.5 g of the sample, accurate to 0.0001 g, and place it in a 250 ml Erlenmeyer flask. Add 50 ml of toluene, boil for 1 min to remove free amine, and cool to room temperature. Add 5–10 drops of bromophenol blue indicator, and titrate with 0.2 mol / L hydrochloric acid standard solution to a yellow endpoint. Calculate the results:

[0092] Z = V * N * 56.1 / m

[0093] In the formula: Z: total amine value, mg / g.

[0094] V: Volume of hydrochloric acid-ethanol standard solution consumed in the titration, in ml;

[0095] N: Concentration of hydrochloric acid-ethanol standard solution, mol / L

[0096] m: Sample weight, g

[0097] The calculation result is rounded to one decimal place.

[0098] Table 2 Performance indicators of the final products of amino-terminated liquid nitrile rubber in Examples 1-10 and Comparative Examples 1-3

[0099]

[0100] The amino value refers to the content of amino (-NH2) groups in amino-terminated liquid nitrile rubber. The amino groups in amino-terminated liquid nitrile rubber are highly reactive and can chemically react with other materials (such as epoxy resins, polyesters, and phenolic resins) or form hydrogen bonds, thereby improving the compatibility of these materials during processing. Therefore, the amino value is an important indicator for measuring the number and activity of amino groups in amino-terminated liquid nitrile rubber, and its content directly affects the processability, heat resistance, toughness, and compatibility with other materials of amino-terminated liquid nitrile rubber.

[0101] The inventors unexpectedly discovered through extensive experimentation that when the amino value in the amino-terminated liquid nitrile rubber is within the range of 55–70 KOH mg / g, the amino-terminated liquid nitrile rubber exhibits better overall performance. This is mainly because this amino value range effectively balances chemical reactivity, processability, and material properties. A suitable amino value ensures that the number of amino groups is sufficient to allow for effective chemical reactions or crosslinking with other polymers (such as epoxy resins and phenolic resins), providing enough active sites to react with the resin, thereby improving the material's impact toughness, mechanical strength, and heat resistance, and thus enhancing the mechanical properties and thermal stability of the blend. An amino value within the range of 55–70 KOH mg / g maintains good flowability and processability in the amino-terminated liquid nitrile rubber, which is beneficial for uniform dispersion during mixing.

[0102] Gel content refers to the amount of cross-linked components in terminal amino liquid nitrile rubber that cannot be dissolved after washing with a specific organic solvent (toluene). Lower gel content results in better flowability and flexibility, along with good solubility, making it suitable for various applications, especially demonstrating superior performance in applications requiring high processability and plasticity.

[0103] Non-volatile content refers to the amount of solids remaining after heating, excluding volatile components such as moisture and organic solvents. High non-volatile content in amino-terminated liquid nitrile rubber results in more stable material properties and prevents adverse effects on performance or the environment due to the release of volatile components during use.

[0104] The amino-terminated liquid nitrile butadiene rubber product prepared by this invention has an amino value of 55-70 KOH mg / g, a gel content of <0.65%, and a non-volatile matter content of ≥99%. The moderate amino value, low gel content, and high non-volatile matter content indicate that the amino-terminated liquid nitrile butadiene rubber product prepared by this invention has high purity, good comprehensive performance in processing and practical applications, and broad application prospects.

[0105] FT-IR schematic diagram of carboxyl-terminated liquid nitrile butadiene rubber is shown below Figure 1 As shown in the figure. From the figure, it can be concluded that the carboxyl-terminated liquid nitrile rubber at 2238 cm⁻¹... -1A strong characteristic absorption peak exists at 1735 cm⁻¹, which is attributed to the triple bond of the cyano group (C≡N). -1 The peak is caused by C=O, and the peak value is 969 cm⁻¹. -1 The characteristic peak represents the 1,4-trans double bond, with a peak value at 921.2 cm⁻¹. -1 The characteristic peaks are attributed to 1,2-vinyl groups.

[0106] The FT-IR schematic diagram of the amino-terminated liquid nitrile rubber prepared in Example 4 is shown below. Figure 2 As shown in the figure, 1538.9cm -1 There is a strong characteristic absorption peak at 3364 cm⁻¹, which is caused by -NH. -1 The absorption peak at that point is caused by NH. This indicates that the present invention has successfully prepared an amino-terminated liquid nitrile rubber.

[0107] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An amino-terminated liquid nitrile rubber, characterized in that, The amino-terminated liquid nitrile rubber has an amino value of 20KOH mg / g to 90KOH mg / g and an acrylonitrile content of 10% to 70%.

2. The amino-terminated liquid nitrile butadiene rubber as described in claim 1, characterized in that, The terminal amino liquid nitrile rubber has a gel content of <1% and a non-volatile content of ≥97%.

3. The method for preparing the amino-terminated liquid nitrile butadiene rubber according to claim 1 or 2, characterized in that, The preparation method includes the following steps: Step 1: Mix terminal carboxyl liquid nitrile rubber with an organic solvent, add an acid catalyst and an acyl halide reagent to react and obtain an acyl chloride derivative; Step 2: Mix the acyl chloride derivative with an organic solvent, add an amine organic compound to react, and obtain an amino-terminated liquid nitrile rubber.

4. The preparation method according to claim 3, characterized in that, The organic solvent is one of dichloromethane, butanone, toluene, xylene, a complex of anhydrous ethanol and xylene, a complex of anhydrous ethanol and butanone, and a complex of anhydrous ethanol and tetrahydrofuran. And / or, the acid catalyst is one of N,N-dimethylformamide, 4-dimethylaminopyridine, and p-toluenesulfonic acid; And / or, the acyl halide reagent is one of formyl chloride, acetyl chloride, benzoyl chloride, oxalyl chloride, chloroacetyl chloride, and trichloroacetyl chloride; And / or, the amine organic compound is one of N-methyl-1,3-propanediamine, 3-terminal amino-1,2,4-triazole, 4,4'-trimethylenedipiperidine, 4-(terminal aminomethyl)piperidine, piperazine, N-(2-aminoethyl)piperazine, and N-(3-terminal aminopropyl)piperazine.

5. The preparation method according to claim 3, characterized in that, In step one, the reaction temperature is -80℃ to 30℃; the reaction time is 3h to 20h. And / or, in step two, the reaction temperature is -80℃ to 30℃; the reaction time is 4h to 18h.

6. The preparation method according to any one of claims 3-5, characterized in that, The equivalent ratio of the terminal carboxyl liquid nitrile rubber to the acid catalyst is 1:(0.05-0.5), preferably 1:(0.1-0.2); And / or, the equivalent ratio of the terminal carboxyl liquid nitrile rubber to the acyl halide reagent is 1:(2-4), preferably 1:(3-4); And / or, the equivalent ratio of the terminal carboxyl liquid nitrile rubber to the amine organic compound is 1:(1-5), preferably 1:(2-4).

7. The preparation method according to any one of claims 3-6, characterized in that, Includes the following steps: Step 1: Dissolve the carboxyl-terminated liquid nitrile rubber in an organic solvent; stir under a nitrogen atmosphere for 10-30 minutes, add an acid catalyst and acyl halide reagent, and react for 3-8 hours to obtain an acyl chloride derivative; remove the solvent from the acyl chloride derivative. Step 2: Dissolve the acyl chloride derivative obtained in Step 1 in an organic solvent, stir under a nitrogen atmosphere for 20 min to 60 min, add an amine organic compound and react for 4 h to 10 h to obtain a crude product of amino reaction. Extract and dry the crude product of amino reaction to obtain terminal amino liquid nitrile rubber.

8. The application of the amino-terminated liquid nitrile rubber according to any one of claims 1-2 and / or the amino-terminated liquid nitrile rubber prepared by the preparation method according to any one of claims 3-7 in the fields of epoxy resin plasticizers, adhesives, sealants, etc.

9. A composite material, characterized in that, The composite material contains the amino-terminated liquid nitrile rubber according to any one of claims 1-2 and / or is prepared from the amino-terminated liquid nitrile rubber according to any one of claims 1-2.

10. A method for plasticizing epoxy resin, characterized in that, This includes reacting the amino-terminated liquid nitrile rubber according to any one of claims 1-2 with epoxy resin.

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