Rapidly vulcanized amidoxime modified nitrile rubber as well as preparation method and application thereof

Abstract

The invention provides rapidly vulcanized amidoxime modified nitrile rubber as well as a preparation method and application thereof, and belongs to the field of rubber materials. The amidoxime modified nitrile rubber prepared by the invention is prepared from the following raw materials in parts by weight: 100 parts of raw amidoxime modified nitrile rubber, 0.1-5 parts of vulcanization accelerator and 20-50 parts of filler. By improving the mixing process of the amidoxime modified nitrile rubber, the amidoxime modified nitrile rubber not only can be quickly vulcanized, but also has excellent mechanical properties. The production process is simplified, the production efficiency is improved, and the method has remarkable industrial application value. The amidoxime modified nitrile rubber material has wide application prospects in the fields of environmental restoration, biological medicine, electronics and the like.

Description

Technical Field

[0001] The present invention belongs to the field of rubber materials, and particularly relates to an amidoxime-modified nitrile rubber with rapid vulcanization, its preparation method and application. Background Art

[0002] Hydrogenated nitrile rubber (HNBR) exhibits excellent oil resistance, outstanding heat resistance and good mechanical properties due to its saturated molecular structure, and is widely used in fields such as automotive and aerospace. However, with the advancement of modern industry towards high precision and high performance, the demand for functionalized rubber materials is becoming increasingly diversified. Amidoximation modification is an effective means of functionalizing HNBR. By introducing amidoxime groups into the HNBR molecular chain, the rubber is endowed with unique properties, such as strong chelating ability for metal ions. This enables amidoxime-modified HNBR to be used in environmental remediation for adsorbing and recovering heavy metal ions in wastewater, as a sensitive material for biosensors in the biomedical field to achieve specific recognition of biomolecules, and as a conductive rubber and battery adhesive with special properties in the electronic field.

[0003] Although amidoxime-modified HNBR has many advantages, current research mainly focuses on modification methods and basic property characterization. There is relatively little research on its vulcanization process during processing, especially on the study of the self-vulcanization characteristics of intramolecular groups. In the rubber processing process, traditional vulcanization processes rely on external vulcanizing agents and vulcanization accelerators, which not only increase production costs but also may affect the purity and stability of rubber products due to vulcanizing agent residues. And amidoxime-modified HNBR molecules contain amidoxime groups and cyano groups, which can undergo self-vulcanization reactions under specific conditions, providing a new idea for simplifying the vulcanization process, improving production efficiency and product quality. However, there is still a lack of precise control of the self-vulcanization conditions of amidoxime-modified HNBR and its systematic research in practical applications.

[0004] Patent application document CN117659228A proposes a new vulcanization method different from external vulcanizing agents, which prepares a nitrile rubber material with self-crosslinking and self-reinforcement through the self-crosslinking action of its own amidoxime bonds and hydrogen bond action. However, the tensile strength of this nitrile rubber material is only up to 28.3 MPa at most, which needs to be further improved. And this method has the following problems: the vulcanization time at vulcanization temperatures below 180 °C in its examples is generally long, all above 30 min, and such a vulcanization rate is too slow for commercial production pursuing economic benefits.

[0005] Therefore, how to optimize the self-vulcanization conditions of amidoxime-modified HNBR, improve the vulcanization efficiency, and at the same time maintain its excellent properties is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0006] The object of the present invention is to provide an amidoxime-modified nitrile rubber with fast vulcanization, its preparation method and application.

[0007] The present invention provides a mixed rubber of amidoxime-modified nitrile rubber, which comprises the following raw materials in parts by weight: 100 parts of amidoxime-modified nitrile rubber raw rubber, 0.1-5 parts of vulcanization accelerator, and 20-50 parts of filler; the amidoxime-modified nitrile rubber raw rubber is obtained by reacting a nitrile rubber containing acrylonitrile with hydroxylamine hydrochloride.

[0008] Further, the mixed rubber of amidoxime-modified nitrile rubber comprises the following raw materials in parts by weight: 100 parts of amidoxime-modified nitrile rubber raw rubber, 0.5-4 parts of vulcanization accelerator, and 20-50 parts of filler, preferably: 100 parts of amidoxime-modified nitrile rubber raw rubber, 2 parts of vulcanization accelerator, and 50 parts of filler.

[0009] In the formula of the present invention, "parts" means parts by weight, and 1 part is 1 g.

[0010] Further, the vulcanization accelerator is a fatty acid or an aromatic acid, preferably stearic acid;

[0011] The filler is any one or a mixture of any several of barium sulfate, calcium silicate, carbon black, diatomite, silicon micropowder and white carbon black, preferably carbon black.

[0012] Further, the mixed rubber of amidoxime-modified nitrile rubber further comprises any one or a mixture of any several of a vulcanizing agent, a co-vulcanizing agent, an acid absorbent, a pigment, a plasticizer, a demolding agent, a metal oxide.

[0013] Further, the vulcanizing agent is selected from 2,4-di-tert-butylcumyl peroxide, benzoyl peroxide or bis(tert-butylperoxyisopropyl)benzene;

[0014] The co-vulcanizing agent is selected from N,N'-m-phenylene bismaleimide, polyfunctional maleimide, triallyl cyanurate or triallyl isocyanurate.

[0015] Further, the preparation method of the amidoxime-modified nitrile rubber raw rubber comprises the following steps: reacting a nitrile rubber solution containing acrylonitrile, hydroxylamine hydrochloride with an alkali solution to obtain the product.

[0016] Further, the acrylonitrile content in the nitrile rubber is 1-60 wt%; the nitrile rubber is ordinary nitrile rubber, carboxyl nitrile rubber or hydrogenated nitrile rubber, preferably hydrogenated nitrile rubber;

[0017] The mass fraction of the nitrile rubber solution containing acrylonitrile is 5-15%, preferably 10%;

[0018] The mass fraction of the alkali solution is 5-20%, preferably 17-18%.

[0019] Furthermore, the molar ratio of acrylonitrile units, hydroxylamine hydrochloride and alkali in the acrylonitrile-containing nitrile rubber is 1:1:1-1.5; the solvent in the acrylonitrile-containing nitrile rubber solution is tetrahydrofuran, toluene, xylene, dichloromethane, dichloroethane, chloroform or acetonitrile; the alkali is sodium hydroxide, potassium hydroxide, lithium hydroxide or anhydrous sodium carbonate; the solvent in the alkali solution is methanol, ethanol or isopropanol; the reaction conditions are: in an inert gas atmosphere, reacting at 30-90 °C for 1-25 h.

[0020] Furthermore, the molar ratio of acrylonitrile units, hydroxylamine hydrochloride and alkali in the acrylonitrile-containing nitrile rubber is 1:1:1.1; the reaction conditions are: in an inert gas atmosphere, reacting at 40-80 °C for 2-24 h.

[0021] Furthermore, the amount of the reaction solvent used is preferably such that it can completely dissolve the monomers and maintain good fluidity of the reaction system, and the amount of the reaction solvent used is 5-10 times the mass of the rubber.

[0022] Furthermore, after the reaction, the following purification steps are also included: after the reaction is completed, adding water for precipitation, washing and drying to obtain the product.

[0023] The present invention also provides a method for preparing the above-mentioned amidoxime-modified nitrile rubber compound, and the method includes the following steps: plasticizing the amidoxime-modified nitrile rubber raw rubber, and then adding the remaining raw materials and kneading evenly, followed by vulcanization to obtain the product.

[0024] Furthermore, the plasticizing conditions are: plasticizing at 10-40 °C for 1-5 min; the vulcanization conditions are: vulcanizing at a pressure of 5-25 MPa and a temperature of 160-200 °C for 1-60 min.

[0025] Furthermore, the plasticizing conditions are: plasticizing at a rotational speed of 40 r·min -1 at 23±1 °C for 2-3 min; the vulcanization conditions are: vulcanizing at a pressure of 10 MPa and a temperature of 180 °C for 1.2 times TC90 + 3 min.

[0026] Furthermore, TC90 represents the process optimum vulcanization time (min), which refers to the time required from the start of heating the rubber compound to when the torque reaches 90% of the maximum torque.

[0027] Furthermore, when the amidoxime-modified nitrile rubber compound is composed of 100 parts of amidoxime-modified nitrile rubber raw rubber, 0.5 part of vulcanization accelerator and 50 parts of filler, TC90 is 29.45 min;

[0028] When the amidoxime-modified nitrile rubber compound consists of 100 parts of amidoxime-modified nitrile rubber raw rubber, 1 part of vulcanization accelerator, and 50 parts of filler, the TC90 is 18.44 min;

[0029] When the amidoxime-modified nitrile rubber compound consists of 100 parts of amidoxime-modified nitrile rubber raw rubber, 2 parts of vulcanization accelerator, and 50 parts of filler, the TC90 is 10.58 min;

[0030] When the amidoxime-modified nitrile rubber compound consists of 100 parts of amidoxime-modified nitrile rubber raw rubber, 3 parts of vulcanization accelerator, and 50 parts of filler, the TC90 is 10.45 min;

[0031] When the amidoxime-modified nitrile rubber compound consists of 100 parts of amidoxime-modified nitrile rubber raw rubber, 4 parts of vulcanization accelerator, and 50 parts of filler, the TC90 is 9.42 min.

[0032] The present invention also provides the use of the above-mentioned amidoxime-modified nitrile rubber compound in preparing materials in the fields of automobiles, aerospace, environmental remediation, biomedicine, and electronics.

[0033] The present invention has achieved the following beneficial effects:

[0034] By improving the amidoxime-modified nitrile rubber mixing process, the amidoxime-modified nitrile rubber of the present invention can not only be vulcanized rapidly but also has excellent mechanical properties. The present invention simplifies the production process, improves the production efficiency, and has significant industrial application value. The amidoxime-modified nitrile rubber material of the present invention has broad application prospects in the fields of environmental remediation, biomedicine, electronics, etc.

[0035] Compared with the nitrile rubber material in the patent application document CN117659228A, the tensile strength of the amidoxime-modified nitrile rubber of the present invention is better, reaching 33.64 MPa; while the highest tensile strength of the nitrile rubber material in the patent application document CN117659228A is only 28.3 MPa. In addition, the vulcanization rate of the preparation method of the present invention is faster, and the vulcanization time of the preferred (Example 3) is only 15 min; while the vulcanization time in the patent application document CN117659228A is all 30 min and above, and the vulcanization rate is too slow.

[0036] Obviously, based on the above content of the present invention, according to the common general knowledge and customary means in the art, without departing from the above basic technical idea of the present invention, various other forms of modification, substitution, or change can be made.

[0037] The following is a further detailed description of the above content of the present invention in the form of specific embodiments. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention. Specific Embodiments

[0038] The raw materials and equipment used in the present invention are all known products, obtained by purchasing commercially available products.

[0039] "Room temperature" as referred to in the present invention means 23 ± 1 °C. The hydrogenated nitrile rubber used in the examples and comparative examples of the present invention is Therban 3406 hydrogenated nitrile rubber from ARLANXEO (the acrylonitrile content in the rubber is 34 ± 1 wt%).

[0040] Example 1. Preparation of amidoxime-modified hydrogenated nitrile rubber compound

[0041] Formulation: 100 parts of amidoxime-modified hydrogenated nitrile raw rubber, 0.5 part of stearic acid, 50 parts of carbon black N550.

[0042] Preparation method:

[0043] (1) Preparation of amidoxime-modified hydrogenated nitrile raw rubber

[0044] Using hydrogenated nitrile rubber containing acrylonitrile as the raw material, it is dissolved (solvent: tetrahydrofuran, solvent dosage: 10 ml / g of hydrogenated nitrile rubber) to prepare a solution with a mass fraction of 10%. Under a nitrogen protection atmosphere, hydroxylamine hydrochloride in a stoichiometric ratio (the molar ratio of acrylonitrile unit to hydroxylamine hydrochloride to base is 1:1:1.1) is added to the solution. After stirring evenly, a 17.4% alkali solution (the alkali solution is a methanol solution of potassium hydroxide, solvent dosage: 6 ml / g of potassium hydroxide) is slowly added dropwise, with the dropping rate controlled at 2 mL / min, the reaction temperature maintained at 40 - 80 °C, and the reaction time is 2 - 24 h. After the reaction is completed, the reaction solution is poured into a large amount of deionized water to precipitate the modified rubber, washed repeatedly until neutral, and then dried to constant weight in a vacuum drying oven at 55 °C to obtain amidoxime-modified hydrogenated nitrile rubber raw rubber.

[0045] (2) Preparation of amidoxime-modified hydrogenated nitrile rubber

[0046] The amidoxime-modified hydrogenated nitrile raw rubber is added to a two-roll open mill and plasticized at room temperature for 2 - 3 min, with the roller speed of 40 r·min -1, carbon black N550 and stearic acid were added. With the roller speed remaining unchanged, after uniform mixing, the roller gap was adjusted to less than 1 mm for wrapping the roller. It was passed through thinly in a triangular wrap and coiled. Finally, the roller gap was adjusted to 2 mm to produce a sheet, obtaining a mixed rubber. The mixed rubber was put into a mold, and on a flat vulcanizer, under the conditions of a pressure of 10 MPa and a temperature of 180 °C, the vulcanization time was 1.2 times TC90 + 3 min (TC90 is shown in Table 1), thus obtaining a mixed rubber of amidoxime-modified hydrogenated nitrile rubber.

[0047] Example 2. Preparation of amidoxime-modified hydrogenated nitrile rubber mixed rubber

[0048] Formulation: 100 parts of amidoxime-modified hydrogenated nitrile raw rubber, 1 part of stearic acid, 50 parts of carbon black N550.

[0049] Preparation method: As described in Example 1.

[0050] Example 3. Preparation of amidoxime-modified hydrogenated nitrile rubber mixed rubber

[0051] Formulation: 100 parts of amidoxime-modified hydrogenated nitrile raw rubber, 2 parts of stearic acid, 50 parts of carbon black N550.

[0052] Preparation method: As described in Example 1.

[0053] Example 4. Preparation of amidoxime-modified hydrogenated nitrile rubber mixed rubber

[0054] Formulation: 100 parts of amidoxime-modified hydrogenated nitrile raw rubber, 3 parts of stearic acid, 50 parts of carbon black N550.

[0055] Preparation method: As described in Example 1.

[0056] Example 5. Preparation of amidoxime-modified hydrogenated nitrile rubber mixed rubber

[0057] Formulation: 100 parts of amidoxime-modified hydrogenated nitrile raw rubber, 4 parts of stearic acid, 50 parts of carbon black N550.

[0058] Preparation method: As described in Example 1.

[0059] The following is the preparation of comparative samples through comparative examples.

[0060] Comparative Example 1. Preparation of amidoxime-modified hydrogenated nitrile rubber mixed rubber

[0061] Formulation: 100 parts of amidoxime-modified hydrogenated nitrile raw rubber, 0 part of stearic acid, 50 parts of carbon black N550.

[0062] Preparation method: As described in Example 1.

[0063] Comparative Example 2. Preparation of unamidoxime-modified hydrogenated nitrile rubber mixed rubber

[0064] Formulation: 100 parts of hydrogenated nitrile raw rubber, 0 part of stearic acid, 50 parts of carbon black N550, 2 parts of BIBP, 4 parts of TAIC.

[0065] Preparation method: as described in Example 1.

[0066] Comparative Example 3. Preparation of un-glyoxime-modified hydrogenated nitrile rubber

[0067] Formulation: 100 parts of hydrogenated nitrile raw rubber, 2 parts of stearic acid, 50 parts of N550, 2 parts of BIBP, 4 parts of TAIC.

[0068] Preparation method: as described in Example 1.

[0069] The beneficial effects of the present invention are demonstrated by the following experimental examples.

[0070] Experimental Example 1. Testing the properties of glyoxime-modified hydrogenated nitrile rubber compound and un-glyoxime-modified hydrogenated nitrile rubber compound

[0071] 1. Experimental method

[0072] Vulcanization tests were carried out on the samples of Examples 1-5 and Comparative Examples 1-3. Test standard: GB / T16584-1996. Test conditions: test equipment GT-M3000A, condition MDR 180°C @ 60 min, Arc 0.5.

[0073] Tensile strength and elongation at break were tested according to the national standard GB / T 528-2009.

[0074] 2. Experimental results

[0075] Table 1 shows the vulcanization test results of the samples.

[0076] Table 1 Vulcanization test results of the samples

[0077] MH ML TS2 TC90 Example 1 26.45 3.35 0.57 29.45 Example 2 24.48 3.32 0.43 18.44 Example 3 20.25 2.46 0.47 10.58 Example 4 18.74 2.20 0.36 10.45 Example 5 17.74 1.80 0.35 9.42 Comparative Example 1 29.45 3.45 1.26 37.27 Comparative Example 2 28.84 1.2 0.28 5.34 Comparative Example 3 24.84 0.98 0.40 5.40

[0078] Among them, ML: minimum torque, N·m (kgf·cm), indicating the fluidity of the rubber compound. The lower ML is, the better the fluidity is, and vice versa.

[0079] MH: maximum torque, N·m (kgf·cm), indicating the shear modulus and crosslinking density of the rubber compound. MH depends on the filler and vulcanization system. The difference between MH and ML (the difference between the maximum and minimum torques) reflects the degree (density) of crosslinking.

[0080] TS2: The time when the stock torque reaches (minimum torque + 2, min). At this time, the vulcanization of the stock reaches a certain rate, which can be indirectly regarded as the time when the stock is basically shaped, representing the operating safety of the stock. The shorter the TS2, the easier the stock is to scorch. After scorching, the fluidity becomes significantly worse, and it may even stop flowing, making the subsequent processing operations unable to run normally. On the contrary, the longer the TS2, although the operating safety processing time is longer, the production efficiency will be lower and the cost will increase significantly;

[0081] TC90: The process true vulcanization time (min), which is the time required from the start of stock heating to when the torque reaches 90% of the maximum torque. It is mainly used to evaluate the primary vulcanization conditions of the stock during molding production. If the TC90 is too long, it means the vulcanization speed is relatively slow and the production efficiency is low.

[0082] By comparing the vulcanization test results of Examples 1 - 5 and Comparative Examples 1 - 3, it can be seen that adding stearic acid to the amidoxime - modified hydrogenated nitrile vulcanization system in Examples 1 - 5 of the present invention can effectively improve its vulcanization rate and promote cross - linking.

[0083] Further comparing Examples 1 - 5 with Comparative Example 1, the technical solution using stearic acid as the accelerator in the amidoxime - modified hydrogenated nitrile vulcanization system significantly improves the vulcanization rate; compared with Comparative Example 2 and Comparative Example 3, Examples 1 - 5 of the present invention using stearic acid as the accelerator in the amidoxime - modified hydrogenated nitrile vulcanization system is only for the amidoxime - modified hydrogenated nitrile rubber.

[0084] Table 2 shows the test results of the mechanical properties of the samples.

[0085] Table 2 Test Results of the Mechanical Properties of Samples

[0086]

[0087] Further comparing the mechanical properties of Examples 1 - 5, it is found that Example 3 using 2 parts of stearic acid as the accelerator in the amidoxime - modified hydrogenated nitrile vulcanization system obtains the optimal tensile strength, achieving unexpected technical effects.

[0088] In summary, the present invention provides an amidoxime - modified nitrile rubber with rapid vulcanization, its preparation method and application. The amidoxime - modified nitrile rubber prepared by the present invention is prepared from the following raw materials in parts by weight: 100 parts of amidoxime - modified nitrile rubber raw rubber, 0.1 - 5 parts of vulcanization accelerator, and 20 - 50 parts of filler. By improving the mixing process of the amidoxime - modified nitrile, the amidoxime - modified nitrile rubber of the present invention can not only be rapidly vulcanized but also has excellent mechanical properties. The present invention simplifies the production process, improves the production efficiency, and has significant industrial application value. The amidoxime - modified nitrile rubber material of the present invention has broad application prospects in the fields of environmental remediation, biomedicine, electronics, etc.

Claims

1. An amidoxime-modified nitrile rubber compound, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of amidoxime-modified nitrile rubber raw rubber, 0.1-5 parts of vulcanization accelerator and 20-50 parts of filler; the amidoxime-modified nitrile rubber raw rubber is obtained by reacting nitrile rubber containing acrylonitrile with hydroxylamine hydrochloride.

2. The amidoxime modified nitrile rubber compound according to claim 1, characterized in that: The amidoxime modified nitrile rubber compound comprises the following raw materials in parts by weight: 100 parts of amidoxime modified nitrile rubber raw rubber, 0.5-4 parts of vulcanization accelerator, and 20-50 parts of filler, preferably: 100 parts of amidoxime modified nitrile rubber raw rubber, 2 parts of vulcanization accelerator, and 50 parts of filler.

3. The amidoxime modified nitrile rubber compound according to claim 1, characterized in that: The vulcanization accelerator is a fatty acid or an aromatic acid, preferably stearic acid; The filler is any one of barium sulfate, calcium silicate, carbon black, diatomaceous earth, silica powder and white carbon black, or a mixture of any two of them, preferably carbon black.

4. The amidoxime modified nitrile rubber compound according to claim 1, characterized in that: The amidoxime-modified nitrile rubber compound further comprises any one or a mixture of any several of a vulcanizer, a vulcanizing agent, an acid absorber, a pigment, a plasticizer, a release agent, and a metal oxide.

5. The amidoxime modified nitrile rubber compound according to claim 1, characterized in that: The preparation method of the amidoxime-modified nitrile rubber raw rubber comprises the following steps: reacting a nitrile rubber solution containing acrylonitrile, hydroxylamine hydrochloride and an alkali solution to obtain the raw rubber.

6. The amidoxime modified nitrile rubber compound according to claim 5, characterized in that: The content of acrylonitrile in the nitrile rubber is 1-60wt%; the nitrile rubber is ordinary nitrile rubber, carboxyl nitrile rubber or hydrogenated nitrile rubber, preferably hydrogenated nitrile rubber; The mass fraction of the acrylonitrile-containing nitrile rubber solution is 5-15%, preferably 10%; The mass fraction of the alkaline solution is 5-20%, preferably 17-18%.

7. The amidoxime modified nitrile rubber compound according to claim 5, characterized in that: The molar ratio of acrylonitrile units, hydroxylamine hydrochloride and alkali in the acrylonitrile-containing nitrile rubber is 1:1:1-1.5; the solvent in the acrylonitrile-containing nitrile rubber solution is tetrahydrofuran, toluene, xylene, dichloromethane, dichloroethane, chloroform or acetonitrile; the alkali is sodium hydroxide, potassium hydroxide, lithium hydroxide or anhydrous sodium carbonate; the solvent in the alkali solution is methanol, ethanol or isopropanol; the reaction conditions are: reacting at 30-90°C for 1-25h under an inert gas atmosphere.

8. A method for preparing the amidoxime-modified nitrile rubber compound according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: plasticizing amidoxime modified nitrile rubber raw rubber, adding other raw materials, mixing evenly, and vulcanizing to obtain the product.

9. The method according to claim 8, characterized in that The plasticizing conditions are: plasticizing at 10-40° C. for 1-5 min; the vulcanization conditions are: vulcanizing at 5-25 MPa pressure and 160-200° C. for 1-60 min.

10. Use of the amidoxime-modified nitrile rubber compound according to any one of claims 1 to 7 in the preparation of materials in the fields of automobiles, aerospace, environmental remediation, biomedicine, and electronics.

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