A rubber vulcanization accelerator and a method for preparing the same

Abstract

This invention relates to the field of rubber technology, and more particularly to a rubber vulcanization accelerator and its preparation method. By weight, the vulcanization accelerator comprises the following raw materials: 7-10 parts of accelerator D, 7-10 parts of accelerator A, 3-5 parts of zinc oxide, 2-5 parts of stearic acid, 2-4 parts of sulfur, and 1-3 parts of 5-norbornene-2-carboxylic acid. This rubber vulcanization accelerator exhibits excellent overall performance and is suitable for the vulcanization processing of various rubber products.

Description

Technical Field

[0001] This invention relates to the field of rubber technology, and in particular to a rubber vulcanization accelerator and its preparation method. Background Technology

[0002] Rubber vulcanization primarily uses sulfur, but the reaction between sulfur and rubber is very slow. Therefore, vulcanization accelerators have emerged. Adding accelerators to rubber compounds activates the vulcanizing agent, accelerating the cross-linking reaction between the vulcanizing agent and rubber molecules, thus shortening vulcanization time and lowering vulcanization temperature. Among existing accelerators, dithioates can rapidly promote vulcanization at conventional vulcanization temperatures, but the heat generated by their own activity often leads to premature scorching of the rubber. Sulfinamides, on the other hand, are slow-acting accelerators and generally do not cause scorching, but they do slow down the vulcanization rate. Furthermore, uneven dispersion of accelerators not only reduces efficiency but also causes localized breakage of long sulfur bonds, resulting in defects in the vulcanization network. Therefore, improving the dispersibility of accelerators and achieving a balance between vulcanization rate and scorch time is crucial for improving the processing safety of rubber compounds and the quality of finished rubber products.

[0003] Furthermore, rubber products are prone to bacterial growth on their surfaces during daily use and in special applications such as medical and hygiene settings, leading to cross-infection or accelerated material aging. Therefore, endowing rubber materials with durable antibacterial properties is of significant practical importance. However, traditional vulcanization accelerators mainly focus on controlling the vulcanization rate and processing safety, generally lacking antibacterial active groups and making it difficult to simultaneously build an antibacterial network during vulcanization. Developing vulcanization accelerators that combine highly efficient vulcanization promotion performance with antibacterial functions has become one of the urgent technical problems to be solved in the field of rubber materials. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a rubber vulcanization accelerator with excellent comprehensive performance, which is suitable for the vulcanization processing of various rubber products.

[0005] The second objective of this invention is to provide a method for preparing a rubber vulcanization accelerator. This method is simple to operate, has mild conditions, good repeatability, and is easy to scale up for production.

[0006] One of the objectives of this invention is achieved through the following technical solution:

[0007] A rubber vulcanization accelerator, by weight, comprises the following raw materials: 7-10 parts of accelerator D (diphenylguanidine), 7-10 parts of accelerator A, 3-5 parts of zinc oxide, 2-5 parts of stearic acid, 2-4 parts of sulfur, and 1-3 parts of 5-norbornene-2-carboxylic acid.

[0008] The structural formula of the accelerator A is: .

[0009] Furthermore, the preparation process of the accelerator A is as follows:

[0010] (1) Add 4-hydroxybenzoyl hydrazine and potassium hydroxide to anhydrous ethanol, add carbon disulfide under ice bath conditions, stir and react, then purify to obtain the product; add the product to deionized water, add hydrazine hydrate, heat and react, purify to obtain intermediate 1;

[0011] The structural formula of intermediate 1 is:

[0012] (2) The intermediate 1 was added to acetonitrile, and then benzyl isothiocyanate was added. After the reaction, the mixture was purified to obtain the promoter A.

[0013] In this invention, 4-hydroxybenzoyl hydrazide is first condensed with carbon disulfide to generate potassium salt of hydrazide dithiocarbamate, and then cyclized at high temperature under the action of hydrazine hydrate to obtain intermediate 1 containing a 1,2,4-triazole-3-thiol skeleton. Further reaction of intermediate 1 with benzyl isothiocyanate yields accelerator A.

[0014] Furthermore, the ratio of 4-hydroxybenzoyl hydrazine, carbon disulfide, potassium hydroxide, and hydrazine hydrate used in step (1) is 1 mmol: (2.5-2.75) mmol: (2.5-2.75) mmol: (0.15-0.2) mL.

[0015] Furthermore, the stirring reaction time in step (1) is 20-24 h; the heating reaction temperature is 100-110 °C and the time is 8-12 h.

[0016] Furthermore, in step (2), the molar ratio of intermediate 1 to benzyl isothiocyanate is 1:(1.05-1.15).

[0017] Furthermore, the reaction time described in step (2) is 16-20 h.

[0018] The second objective of this invention is achieved by the following technical solution:

[0019] The preparation method of the above-mentioned rubber vulcanization accelerator includes the following steps:

[0020] Stearic acid and 5-norbornene-2-carboxylic acid are stirred evenly, and then accelerator D, accelerator A, zinc oxide and sulfur are added and mixed evenly to obtain the final product.

[0021] Furthermore, the stirring temperature is 70-80℃ and the stirring time is 15-20 minutes.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) This invention provides a rubber vulcanization accelerator, which is composed of accelerator A, accelerator D, 5-norbornene-2-carboxylic acid, zinc oxide, stearic acid and sulfur. The vulcanization accelerator has good synergistic properties and excellent overall performance.

[0024] (2) This invention, by compounding accelerator A with accelerator D, significantly accelerates the vulcanization speed and improves the vulcanization efficiency while ensuring good scorch safety. Specifically, accelerator A exhibits good scorch safety at room temperature, and rapidly releases its activity at the vulcanization temperature, achieving efficient vulcanization and improving the mechanical properties of the rubber material. At the same time, accelerator A contains antibacterial active groups such as triazole, which can endow the rubber material with good antibacterial and antifungal properties.

[0025] (3) By introducing 5-norbornene-2-carboxylic acid, this invention effectively improves the dispersion of each component in the rubber matrix, enhances the uniformity of vulcanization, strengthens the system's resistance to vulcanization reversion, significantly improves the aging resistance of rubber materials, and stabilizes the quality of finished products.

[0026] (4) The present invention also provides a method for preparing a vulcanization accelerator, which is simple to operate, mild in conditions, has good repeatability, and is easy to scale up. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0028] Example 1

[0029] A rubber vulcanization accelerator, by weight, comprises the following raw materials: 9 parts of accelerator D (CAS: 102-06-7), 8 parts of accelerator A, 4 parts of zinc oxide, 3 parts of stearic acid, 2 parts of 5-norbornene-2-carboxylic acid (CAS: 120-74-1), and 3 parts of sulfur.

[0030] The preparation process of the above-mentioned accelerator A is as follows:

[0031] (1) Using 4-hydroxybenzoyl hydrazine, carbon disulfide, potassium hydroxide, anhydrous ethanol, deionized water, and hydrazine hydrate in a ratio of 20 mmol: 52 mmol: 52 mmol: 22 mL: 1 mL: 3.6 mL, 4-hydroxybenzoyl hydrazine and potassium hydroxide were added to anhydrous ethanol. Under ice bath conditions, carbon disulfide was added dropwise, and the mixture was stirred for 22 h. The solvent was removed by rotary evaporation. The residue was washed with n-hexane, dried under vacuum, and then added to deionized water. Hydrazine hydrate was added dropwise, and the mixture was reacted at 105 °C for 10 h. After cooling to room temperature, the reactants were diluted with ice water, and dilute hydrochloric acid solution was added dropwise to precipitate the product. The product was filtered, washed with ice water, and dried under vacuum to obtain intermediate 1 (yield 60.5%). The NMR and mass spectrometry results of intermediate 1 are as follows:

[0032] 1 HNMR: (C8H8ON4S, 400MHz, DMSO-d6) δ: 5.70 (s, 2H), 6.86-6.90 (d, 2H), 7.70-7.74 (d, 2H), 9.67 (s, 1H), 13.89 (s, 1H). MS (ESI) m / z=208.04[M].

[0033] (2) With intermediate 1, benzyl isothiocyanate, and acetonitrile in a ratio of 6 mmol:6.6 mmol:24 mL, intermediate 1 was dissolved in acetonitrile, benzyl isothiocyanate was added, and the mixture was reacted at room temperature for 18 h. The solvent was then removed by rotary evaporation, and the residue was subjected to column chromatography (V) 二氯甲烷 V 甲醇 The ratio of the sample to the final product (8:1~6:1) was purified to obtain promoter A (yield 65.4%); the NMR and mass spectrometry results of promoter A are as follows:

[0034] 1 HNMR: (C 16 H 15 OS2N5, 400MHz, DMSO-d6) δ: 4.72 (s, 2H), 6.86-6.90 (d, 2H), 7.25-7.33 (m, 5H), 7.68-7.74 (m, 3H), 8.15 (s, 1H), 9.67 (s, 1H), 13.79 (s, 1H). MS (ESI) m / z=357.07[M].

[0035] The preparation method of the above-mentioned rubber vulcanization accelerator includes the following steps:

[0036] Stearic acid and 5-norbornene-2-carboxylic acid were stirred at 75°C for 18 minutes, and then accelerator D, accelerator A, zinc oxide and sulfur were added and mixed evenly to obtain the final product.

[0037] Example 2

[0038] A rubber vulcanization accelerator, by weight, comprises the following raw materials: 10 parts of accelerator D, 10 parts of accelerator A, 5 parts of zinc oxide, 5 parts of stearic acid, 3 parts of 5-norbornene-2-carboxylic acid, and 4 parts of sulfur.

[0039] The preparation process of the above-mentioned accelerator A is as follows:

[0040] (1) With the following ratio of 4-hydroxybenzoyl hydrazine, carbon disulfide, potassium hydroxide, anhydrous ethanol, deionized water and hydrazine hydrate being 20 mmol: 55 mmol: 55 mmol: 26 mL: 1 mL: 4 mL, 4-hydroxybenzoyl hydrazine and potassium hydroxide were added to anhydrous ethanol. Carbon disulfide was added dropwise under ice bath conditions, and the mixture was stirred for 24 h. The solvent was removed by rotary evaporation. The residue was washed with n-hexane, dried under vacuum, and then added to deionized water. Hydrazine hydrate was added dropwise, and the mixture was reacted at 110 °C for 8 h. After cooling to room temperature, the reactants were diluted with ice water, and dilute hydrochloric acid solution was added dropwise to precipitate the product. The product was filtered, washed with ice water, and dried under vacuum to obtain intermediate 1 (yield 55.3%). The NMR and mass spectrometry results of intermediate 1 were consistent with those of Example 1.

[0041] (2) With intermediate 1, benzyl isothiocyanate, and acetonitrile in a ratio of 6 mmol:6.9 mmol:27 mL, intermediate 1 was dissolved in acetonitrile, benzyl isothiocyanate was added, and the mixture was reacted at room temperature for 20 h. The solvent was then removed by rotary evaporation, and the residue was subjected to column chromatography (V) 二氯甲烷 V 甲醇 The ratio of 8:1 to 6:1 was purified to obtain promoter A (yield of 60.9%); the NMR and mass spectrometry results of promoter A were consistent with those of Example 1.

[0042] The preparation method of the above-mentioned rubber vulcanization accelerator includes the following steps:

[0043] Stearic acid and 5-norbornene-2-carboxylic acid are stirred at 80°C for 15 minutes, and then accelerator D, accelerator A, zinc oxide and sulfur are added and mixed evenly to obtain the final product.

[0044] Example 3

[0045] A rubber vulcanization accelerator, by weight, comprises the following raw materials: 7 parts accelerator D, 7 parts accelerator A, 3 parts zinc oxide, 2 parts stearic acid, 1 part 5-norbornene-2-carboxylic acid, and 2 parts sulfur.

[0046] The preparation process of the above-mentioned accelerator A is as follows:

[0047] (1) With the ratio of 4-hydroxybenzoyl hydrazine, carbon disulfide, potassium hydroxide, anhydrous ethanol, deionized water and hydrazine hydrate being 20 mmol: 50 mmol: 50 mmol: 20 mL: 1 mL: 3 mL, 4-hydroxybenzoyl hydrazine and potassium hydroxide were added to anhydrous ethanol. Under ice bath conditions, carbon disulfide was added dropwise, and the mixture was stirred for 20 h. The solvent was removed by rotary evaporation. The residue was washed with n-hexane, dried under vacuum, and then added to deionized water. Hydrazine hydrate was added dropwise, and the mixture was reacted at 100 °C for 12 h. After cooling to room temperature, the reactants were diluted with ice water, and dilute hydrochloric acid solution was added dropwise to precipitate the product. The product was filtered, washed with ice water, and dried under vacuum to obtain intermediate 1 (yield of 56.2%). The NMR and mass spectrometry results of intermediate 1 were consistent with those of Example 1.

[0048] (2) With intermediate 1, benzyl isothiocyanate, and acetonitrile in a ratio of 6 mmol:6.3 mmol:18 mL, intermediate 1 was dissolved in acetonitrile, benzyl isothiocyanate was added, and the mixture was reacted at room temperature for 16 h. The solvent was then removed by rotary evaporation, and the residue was subjected to column chromatography (V) 二氯甲烷 V 甲醇 The ratio of 8:1 to 6:1 was purified to obtain promoter A (yield of 61.7%); the NMR and mass spectrometry results of promoter A were consistent with those of Example 1.

[0049] The preparation method of the above-mentioned rubber vulcanization accelerator includes the following steps:

[0050] Stearic acid and 5-norbornene-2-carboxylic acid are stirred at 70°C for 20 minutes. Then, accelerator D, accelerator A, zinc oxide and sulfur are added and mixed evenly to obtain the final product.

[0051] Comparative Example 1

[0052] The difference between Comparative Example 1 and Example 1 is that accelerator A is omitted.

[0053] Comparative Example 2

[0054] The difference between Comparative Example 2 and Example 1 is that 5-norbornene-2-carboxylic acid is omitted.

[0055] Experimental Example 1

[0056] Weigh out 100 parts by weight of natural rubber, 40 parts by weight of carbon black, and 5 parts by weight of the vulcanization accelerator corresponding to the examples or comparative examples, and set aside. Add the natural rubber to a mixer and mix at 60°C and 45 rpm. After mixing evenly, add the carbon black and continue mixing at 60°C for 10 minutes. After discharging the rubber and cooling to room temperature, transfer it to a two-roll mill and roll it. Then add the corresponding vulcanization accelerator and mix at 20°C for 6 minutes. Perform thin-pass and triangular wrapping treatments, and vulcanize at 150°C to obtain the various rubber materials.

[0057] The vulcanization characteristics of each rubber material were tested according to GB / T 9869-2014, and the results are shown in Table 1.

[0058] The antibacterial properties of various rubber materials were tested according to GB / T 31402-2023. The test strain was Staphylococcus aureus ATCC6538, and the results are shown in Table 2.

[0059] The tensile properties of dumbbell-shaped specimens were tested according to GB / T 528-2009, with a tensile rate of 500 mm / min. The results are shown in Table 2.

[0060] The tear strength of the tear specimens was tested according to GB / T 529-2008 at a test speed of 500 mm / min. The results are shown in Table 2.

[0061] The tensile strength was measured in accordance with the standard GB / T 3512-2014 "Accelerated Aging and Heat Resistance Test of Vulcanized Rubber or Thermoplastic Rubber in Hot Air". A type 1 laminar flow air aging chamber was used with an air flow rate of 1 m / s. After treatment at 100℃ for 72 h, the change rate of tensile strength was measured. The results are shown in Table 2.

[0062] Table 1 Example 1 6.94 10.17 22.40 1.07 Example 2 6.68 10.15 21.56 1.24 Example 3 6.82 10.20 21.73 1.11 Comparative Example 1 5.46 11.22 15.85 1.83 Comparative Example 2 6.11 10.64 20.62 1.49

[0063] Table 2 Example 1 25.07 43.13 -2.1 99.5 Example 2 24.21 41.05 -3.6 99.1 Example 3 24.63 41.67 -2.8 99.4 Comparative Example 1 17.92 31.48 -4.3 45.3 Comparative Example 2 21.58 36.74 -16.9 99.0

[0064] As shown in Table 1, the T values ​​in Examples 1-3 are... 10 The scorching time was 6.68-6.94 min, longer than that of Comparative Example 1, indicating that adding accelerator A can effectively prolong the scorching time and improve processing safety. The T values ​​of Examples 1-3... 90 The time was 10.15-10.20 min, significantly shorter than that of Comparative Example 1, indicating that the combination of accelerator A and accelerator D significantly accelerated the vulcanization rate. M in Examples 1-3 H Significantly higher than Comparative Example 1, M L The results were significantly lower than those of Comparative Example 1, indicating that the combination of accelerator A and accelerator D increased the crosslinking density and improved the processing fluidity of the rubber compound.

[0065] Table 2 shows that the tensile strength and tear strength of Examples 1-3 are significantly higher than those of Comparative Example 1, indicating that the combination of accelerator A and accelerator D improves the mechanical properties of the rubber. The absolute value of the change rate of tensile strength in Examples 1-3 is significantly smaller than that in Comparative Example 2, indicating that 5-norbornene-2-carboxylic acid plays a key role in improving the resistance to thermo-oxidative aging. Meanwhile, the antibacterial rate of Examples 1-3 is much higher than that of Comparative Example 1, confirming that the triazole group in accelerator A is the main source of its antibacterial properties.

[0066] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A rubber vulcanization accelerator, characterized in that, By weight, it includes the following raw materials: 7-10 parts of accelerator D, 7-10 parts of accelerator A, 3-5 parts of zinc oxide, 2-5 parts of stearic acid, 2-4 parts of sulfur, and 1-3 parts of 5-norbornene-2-carboxylic acid; The structural formula of the accelerator A is: 。 2. The rubber vulcanization accelerator according to claim 1, characterized in that, The preparation process of the accelerator A is as follows: (1) Add 4-hydroxybenzoyl hydrazine and potassium hydroxide to anhydrous ethanol, add carbon disulfide under ice bath conditions, stir and react, then purify to obtain the product; add the product to deionized water, add hydrazine hydrate, heat and react, purify to obtain intermediate 1; The structural formula of intermediate 1 is: (2) The intermediate 1 was added to acetonitrile, and then benzyl isothiocyanate was added. After the reaction, the mixture was purified to obtain the promoter A.

3. The rubber vulcanization accelerator according to claim 2, characterized in that, The ratio of 4-hydroxybenzoyl hydrazine, carbon disulfide, potassium hydroxide and hydrazine hydrate used in step (1) is 1 mmol: (2.5-2.75) mmol: (2.5-2.75) mmol: (0.15-0.2) mL.

4. The rubber vulcanization accelerator according to claim 2, characterized in that, The stirring reaction in step (1) takes 20-24 hours; the heating reaction takes 100-110°C for 8-12 hours.

5. The rubber vulcanization accelerator according to claim 2, characterized in that, The molar ratio of intermediate 1 and benzyl isothiocyanate in step (2) is 1:(1.05-1.15).

6. The rubber vulcanization accelerator according to claim 2, characterized in that, The reaction time in step (2) is 16-20 hours.

7. A method for preparing the rubber vulcanization accelerator according to any one of claims 1-6, characterized in that, Includes the following steps: Stearic acid and 5-norbornene-2-carboxylic acid are stirred evenly, and then accelerator D, accelerator A, zinc oxide and sulfur are added and mixed evenly to obtain the final product.

8. The method for preparing the rubber vulcanization accelerator according to claim 7, characterized in that, The stirring temperature is 70-80℃, and the stirring time is 15-20 minutes.

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