A dibutyl dithiophosphate selenium accelerator for resisting reversion rubber, its preparation method and application

Abstract

This invention discloses a reversion-resistant rubber accelerator, dibutyl dithiophosphate selenium, its preparation method, and its application, belonging to the technical field of rubber vulcanization accelerators. The preparation method includes the following steps: adding hydrochloric acid solution to selenium dioxide solution under stirring to obtain a mixed solution; then adding the mixed solution dropwise to dibutyl dithiophosphate ammonium solution, followed by stirring after the addition is complete; after the stirring reaction is completed, separating, washing, and drying yields the reversion-resistant rubber accelerator, dibutyl dithiophosphate selenium. The synthesis process employed in this invention is simple to operate, has a short reaction time, and is low in cost; the obtained rubber accelerator not only has good vulcanization promotion effect and excellent reversion resistance, but its molecular structure also does not contain nitrogen, fundamentally avoiding the generation of toxic N-nitrosamine carcinogens during the vulcanization process.

Description

Technical Field

[0001] This invention belongs to the technical field of rubber vulcanization accelerators, specifically relating to a dibutyl dithiophosphate selenium accelerator for resisting reversion to vulcanization, its preparation method, and its application. Background Technology

[0002] The vulcanization reaction of rubber refers to the chemical transformation of rubber molecules from a linear structure to a three-dimensional network structure. Rubber materials only have practical application value after vulcanization. Rubber accelerators are substances that promote the reaction between rubber and vulcanizing agents; they not only increase the vulcanization rate, lower the vulcanization temperature, and shorten the vulcanization time, but also improve the physical, mechanical, and chemical properties of the vulcanized rubber.

[0003] Rubber accelerators can be classified into eight categories according to their chemical structure. Most of these thiuram-based accelerators (such as TMTD, TETD, TMTM), dithiocarbamate-based accelerators (such as ZDMC, ZDC), and sulfenamide-based accelerators (such as NOBS, DIBS, DZ) contain secondary amine structures in their molecular structures. During vulcanization, these accelerators are prone to producing toxic N-nitrosamine carcinogens, which pose serious harm to the environment and human health. This does not align with the current green and environmentally friendly development concept of rubber accelerators, as outlined in "Clean Production and Environmentally Friendly Product Development of Rubber Accelerators".

[0004] During the vulcanization process of rubber, the degradation of cross-linked networks caused by high vulcanization temperature and excessively long vulcanization time, leading to a decline in the performance of the vulcanized rubber, is called reversion (see "Research on the Reversion Resistance of Natural Rubber Compounds"). Thick rubber products such as tires require a long vulcanization time to ensure sufficient vulcanization of the inner layer, which can easily lead to over-vulcanization of the outer layer and reversion. Simultaneously, radial tires are also prone to reversion due to heat generation during high-speed driving, which affects tire safety and service life. Methods to improve reversion resistance include using semi-efficient vulcanization systems, adjusting the raw rubber system, and adding anti-reversion agents, but these methods each have their limitations.

[0005] Zinc dibutyldithiophosphate (ZBPD) is an environmentally friendly accelerator. However, its vulcanization efficiency is low when used as a primary accelerator in natural rubber, so it is generally used as a secondary accelerator in combination with other accelerators to improve resistance to reversion. Selenium, a sulfur homologue, has been shown to participate in rubber crosslinking. Therefore, combining selenium with dibutyldithiophosphate ligands to synthesize selenium dibutyldithiophosphate, a rubber accelerator possessing both high efficiency, environmental friendliness, and resistance to reversion, has broad application prospects. Summary of the Invention

[0006] In order to overcome the shortcomings and deficiencies of the existing technology and expand the application scope of dithiophosphate rubber accelerators, the present invention aims to provide a dibutyl dithiophosphate selenium accelerator for resisting reversion rubber, its preparation method and application.

[0007] The objective of this invention is achieved through the following technical solutions.

[0008] A dibutyl dithiophosphate selenium accelerator for resisting reversion rubber has the following structural formula:

[0009]

[0010] The preparation method of the above-mentioned anti-reversion rubber accelerator dibutyl dithiophosphate selenium includes the following steps:

[0011] Hydrochloric acid solution was added to selenium dioxide solution under stirring conditions to obtain a mixed solution; then the mixed solution was slowly added dropwise to dibutyl dithiophosphate ammonium solution, and after the addition was completed, the mixture was stirred at low temperature for a period of time; after the stirring reaction was completed, the mixture was separated, washed and dried to obtain the anti-sulfurization reversion rubber accelerator dibutyl dithiophosphate selenium.

[0012] Furthermore, the solvent for the selenium dioxide solution is deionized water with a concentration of 0.10–0.13 g / ml.

[0013] Furthermore, the solvent for the dibutyldithiophosphate ammonium solution is deionized water with a concentration of 0.06–0.11 g / ml.

[0014] Furthermore, the hydrochloric acid solution contains 35% to 38% hydrochloric acid by mass.

[0015] Furthermore, the molar ratio of selenium dioxide, hydrochloric acid, and dibutyldithiophosphate is 1:4 to 4.5:4 to 4.5.

[0016] Furthermore, the volume ratio of the selenium dioxide solution to the dibutyldithiophosphate ammonium solution is 1:10-15.

[0017] Furthermore, the stirring rate of the stirring reaction is 400-600 rpm, the temperature of the stirring reaction is 2-10℃, and the stirring reaction time is 2-4 h.

[0018] Furthermore, the mixed solution is added drop by drop.

[0019] Furthermore, before the mixed solution is slowly added dropwise to the dibutyldithiophosphate solution, the mixed solution and the dibutyldithiophosphate solution are stirred at 0–10°C for 10–20 min respectively.

[0020] Furthermore, the selenium dioxide is sourced from commercially available selenium dioxide with a purity of 99%.

[0021] Furthermore, the source of the dibutyl dithiophosphate is commercially available dibutyl dithiophosphate with a purity of 95%.

[0022] The anti-reversion rubber accelerator dibutyl dithiophosphate selenium provided by the present invention is a yellow-green oily liquid; the preparation method of the anti-reversion rubber accelerator dibutyl dithiophosphate selenium of the present invention has a yield of 77.4% to 82.7%.

[0023] The above-mentioned anti-reversion rubber accelerator, dibutyl dithiophosphate selenium, is used in the preparation of rubber.

[0024] Furthermore, the vulcanization temperature for preparing the rubber is 160–180°C. High-temperature vulcanization results in high efficiency and prevents reversion.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] (1) The preparation method provided by the present invention adopts a one-pot synthesis process, which is simple to operate, has a short reaction time, high yield, and is easy to realize industrial production.

[0027] (2) The preparation method provided by the present invention produces ammonium chloride as a byproduct of the reaction, which can be recycled and used as industrial ammonium chloride.

[0028] (3) The anti-reversion rubber accelerator dibutyl dithiophosphate selenium molecule structure prepared by the present invention does not contain nitrogen element, which fundamentally avoids the generation of toxic N-nitrosamine carcinogens and conforms to the current green and environmentally friendly development concept of rubber accelerators.

[0029] (4) The anti-reversion rubber accelerator dibutyl dithiophosphate selenium prepared by this invention has high vulcanization efficiency and excellent anti-reversion performance. Its anti-reversion effect after high-temperature vulcanization is far superior to that of commonly used accelerators (M, ZBPD, ZDC), which is of great significance for thick rubber products such as tires. Attached Figure Description

[0030] Figure 1 The vulcanization curves are for the compound rubbers prepared in Examples 4-6, where NR / SBPD represents the compound rubber.

[0031] Figure 2 The vulcanization curves of the rubber compounds prepared in Example 4 and Comparative Examples 1-3 at 160°C are shown.

[0032] Figure 3 The vulcanization curves of the rubber compounds prepared in Example 4 and Comparative Examples 1-3 at 180°C are shown.

[0033] Figure 4 The graph shows the relationship between the reversion rate and vulcanization time of the compound rubber prepared in Example 4 and Comparative Examples 1-3 at 180°C.

[0034] Figure 5 The image shows the tensile curves of the rubber compounds prepared in Example 4 and Comparative Examples 1-3.

[0035] Figure 6 The infrared spectrum of selenium dibutyl dithiophosphate prepared in Example 1.

[0036] Figure 7 The Raman spectrum of selenium dibutyl dithiophosphate prepared in Example 1. Detailed Implementation

[0037] The following embodiments further illustrate the specific implementation of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0038] The natural rubber and sulfur masterbatch described in the following examples were purchased from Dongguan Siqi Rubber Technology Co., Ltd., and the open mill was a small 6-inch rubber mixing mill for experimental use manufactured by Guangdong Lina Industrial Co., Ltd.

[0039] Example 1

[0040] 1.12 g (0.01 mol) of selenium dioxide was dissolved in 10 ml of deionized water under stirring at 500 rpm, and then 4 ml of hydrochloric acid solution (mass fraction 37%) was added to obtain a mixed solution. 10.91 g (0.04 mol) of dibutyldithiophosphate was dissolved in 100 ml of deionized water to obtain a dibutyldithiophosphate solution. Both solutions were stirred separately at 10 °C for 20 min, and then the mixed solution was added dropwise to the dibutyldithiophosphate solution. The reaction was carried out under stirring at 500 rpm, with the reaction temperature controlled at 10 °C, and maintained at this temperature for 4 h. After the reaction was completed, the product was separated, washed, and dried to obtain the anti-reversion rubber accelerator dibutyldithiophosphate selenium. The obtained product was a yellow-green oily liquid with a yield of 79.3%.

[0041] Example 2

[0042] 1.12 g (0.01 mol) of selenium dioxide was dissolved in 10 ml of deionized water under stirring at 400 rpm, and then 4 ml of hydrochloric acid solution (mass fraction 37%) was added to obtain a mixed solution. 12.23 g (0.045 mol) of dibutyldithiophosphate was dissolved in 150 ml of deionized water to obtain a dibutyldithiophosphate solution. Both solutions were stirred separately at 6 °C for 15 min, and then the mixed solution was added dropwise to the dibutyldithiophosphate solution. The reaction was carried out under stirring at 400 rpm, with the reaction temperature controlled at 6 °C, and maintained at this temperature for 3 h. After the reaction was completed, the product was separated, washed, and dried to obtain the anti-reversion rubber accelerator dibutyldithiophosphate selenium. The obtained product was a yellowish-green oily liquid with a yield of 82.7%.

[0043] Example 3

[0044] 1.12 g (0.01 mol) of selenium dioxide was dissolved in 10 ml of deionized water under stirring at 600 rpm, and then 4 ml of hydrochloric acid solution (mass fraction 37%) was added to obtain a mixed solution. 12.23 g (0.045 mol) of dibutyldithiophosphate was dissolved in 150 ml of deionized water to obtain a dibutyldithiophosphate solution. Both solutions were stirred separately at 2°C for 10 min, and then the mixed solution was added dropwise to the dibutyldithiophosphate solution. The reaction was carried out under stirring at 600 rpm, with the reaction temperature controlled at 2°C, and maintained at this temperature for 2 h. After the reaction was completed, the product was separated, washed, and dried to obtain the anti-reversion rubber accelerator dibutyldithiophosphate selenium. The obtained product was a yellowish-green oily liquid with a yield of 77.4%.

[0045] Example 4

[0046] The following compound was prepared by adding 50g of N550 carbon black, 3.125g of sulfur masterbatch (80% sulfur content), 1g of dibutyl dithiophosphate selenium (prepared from Example 1), 6.25g of zinc oxide (80% content), and 2g of stearic acid to 100g of natural rubber (NR) using an open mill: NR / SBPD. This compound was then vulcanized at 160°C, and its vulcanization curve is shown below. Figure 1 As shown, its vulcanization parameters are shown in Table 1.

[0047] Example 5

[0048] The following compound was prepared by adding 50g of N550 carbon black, 3.125g of sulfur masterbatch (80% sulfur content), 1g of dibutyl dithiophosphate selenium (prepared from Example 2), 6.25g of zinc oxide (80% content), and 2g of stearic acid to 100g of natural rubber (NR) using an open mill: [Insert compound here]. The compound was then vulcanized at 160°C, and the vulcanization curve is shown below. Figure 1 As shown.

[0049] Example 6

[0050] The following compound was prepared by adding 50g of N550 carbon black, 3.125g of sulfur masterbatch (80% sulfur content), 1g of dibutyl dithiophosphate selenium (prepared from Example 3), 6.25g of zinc oxide (80% content), and 2g of stearic acid to 100g of natural rubber (NR) using an open mill: [Insert compound here]. The compound was then vulcanized at 160°C, and its vulcanization curve is shown below. Figure 1 As shown.

[0051] Figure 1 The vulcanization curves of the vulcanizates obtained in Examples 4-6 are shown below. Figure 1 It can be concluded that the vulcanization curves of the rubber compounds obtained in Examples 4, 5, and 6 are basically the same, and the scorch time, positive vulcanization time, and maximum torque are basically the same. Therefore, the rubber compound of Example 4 is selected for comparison and explanation.

[0052] Comparative Example 1

[0053] The following compound, denoted as NR / M, was prepared by adding 50g of N550 carbon black, 3.125g of sulfur masterbatch (80% sulfur content), 1g of 2-mercaptobenzothiazole (medium-speed accelerator M), 6.25g of zinc oxide (80% content), and 2g of stearic acid to 100g of natural rubber (NR) using an open mill: [Insert compound name here]. The compound was then vulcanized at 160℃, and its vulcanization curve is shown below. Figure 2 As shown, its vulcanization parameters are shown in Table 1.

[0054] Comparative Example 2

[0055] The following compound, NR / ZBPD, is prepared by adding 50g N550 carbon black, 3.125g sulfur masterbatch (80% sulfur content), 1g zinc dibutyl dithiophosphate (environmentally friendly accelerator ZBPD), 6.25g zinc oxide (80% content), and 2g stearic acid to 100g of natural rubber (NR) using an open mill: NR / ZBPD. This compound is then vulcanized at 160℃, and its vulcanization curve is shown below. Figure 2 As shown, its vulcanization parameters are shown in Table 1.

[0056] Comparative Example 3

[0057] The following compound, denoted as NR / ZDC, was prepared by adding 50g N550 carbon black, 3.125g sulfur masterbatch (80% sulfur content), 1g zinc diethyldithiocarbamate (ZDC), 6.25g zinc oxide (80% content), and 2g stearic acid to 100g of natural rubber (NR) using an open mill: NR / ZDC. This compound was then vulcanized at 160℃, and its vulcanization curve is shown below. Figure 2 As shown in Table 1, its vulcanization parameters are as follows.

[0058] The vulcanization parameters of the rubber compounds obtained in Examples 4 and Comparative Examples 1-3 are shown in Table 1, and the vulcanization curves of the rubber compounds obtained in Examples 4 and Comparative Examples 1-3 are shown in Table 1. Figure 2 From Table 1 and Figure 2 It can be seen that among the four accelerators, dibutyl dithiophosphate selenium (NR / SBPD) has the best vulcanization rate, the highest torque, the best resistance to reversion, and is the least prone to scorching.

[0059] Table 1. Vulcanization parameters of the rubber compounds obtained in Example 4 and Comparative Examples 1-3

[0060]

[0061] To compare the high-temperature resistance to reversion of the four accelerators, the vulcanization temperature was increased to 180°C, and the high-temperature vulcanization curves of the compounds prepared in Example 4 and Comparative Examples 1-3 were obtained. Figure 3 Reversion rate and vulcanization time curve Figure 4 And Table 2, which contains parameters for high-temperature vulcanization reversion; Figure 3 , Figure 4 As shown in Table 2, at 180℃ and a vulcanization time of 20 min, among the four accelerators, dibutyl dithiophosphate selenium (NR / SBPD) exhibits the best vulcanization flatness, the latest reversion time, and the lowest reversion rate of only 2.8%, with almost no vulcanization reversion occurring, demonstrating excellent high-temperature resistance to vulcanization reversion.

[0062] Table 2. High-temperature vulcanization reversion parameters of the rubber compounds prepared in Example 4 and Comparative Examples 1-3

[0063]

[0064] Tensile strength, elongation at break, elongation at a given elongation, and tear strength were tested according to standard GB / T528.

[0065] The crosslinking density of NR vulcanizates was determined using the equilibrium swelling method. Three groups of vulcanizates, each approximately 0.2 g in size, were prepared and their initial mass (m1) was recorded. After swelling with toluene for 72 hours, the samples were quickly removed, the surface solvent was wiped off, and the swollen mass (m2) was recorded. The samples were then placed in a fume hood to evaporate for two days, and finally transferred to a vacuum oven to dry to constant weight, with the dried mass (m3) recorded. The equilibrium crosslinking density was calculated using the Flory-Rehner formula.

[0066] Volume fraction Vr in swollen rubber:

[0067] Crosslinking density Ve:

[0068] In the formula, ρ is the mass fraction of NR in the sample, α is the mass loss ratio of the sample after swelling, and ρ is the mass fraction of NR in the sample.r ρ represents the density of rubber. s χ represents the density of toluene, and χ is the interaction parameter between NR and toluene, with a value of 0.393.

[0069] The physical property parameters of the compound rubbers obtained in Example 4 and Comparative Examples 1-3 are shown in Table 3. Figure 5 The images show the tensile curves of the rubber compounds obtained in Example 4 and Comparative Examples 1-3. Figure 5 As shown in Table 3, the physical properties of NR / SBPD vulcanizate are enhanced compared to the other three accelerators. Specifically, the tensile strength increases by 5.8% compared to NR / M, and by 7.2% compared to NR / ZBPD, but is lower than NR / ZDC; the 100% elongation increases by 61.3% compared to NR / M, 67.8% compared to NR / ZBPD, and 14.5% compared to NR / ZDC; the 300% elongation increases by 68.2% compared to NR / M, 73.7% compared to NR / ZBPD, and 13.6% compared to NR / ZDC; the tear strength increases by 3.2% compared to NR / M and 4.7% compared to NR / ZBPD, but is lower than NR / ZDC; and the crosslinking density increases by 80.4% compared to NR / M, 89.2% compared to NR / ZBPD, and 27.8% compared to NR / ZDC.

[0070] Table 3 shows the physical property parameters of the compound obtained in Example 4 and Comparative Examples 1 to 3.

[0071]

[0072] The infrared spectrum of the dibutyl dithiophosphate selenium prepared in Example 1 of this invention is shown below. Figure 6 As shown in the figure, 2964cm -1 It is the stretching vibration peak of CH in -CH3; 2871 cm⁻¹ -1 It is the stretching vibration peak of CH in -CH2-; 1128 cm⁻¹ -1 It is the stretching vibration peak of CO in COP; 992 cm⁻¹ -1 It is the stretching vibration peak of PO in POC; 853 cm⁻¹ -1 It is the vibrational peak of P=S; 660cm -1 These are the stretching vibration peaks of PS. These data indicate the presence of dibutyl dithiophosphate ligands in the product.

[0073] The Raman spectrum of the dibutyl dithiophosphate selenium prepared in Example 1 of this invention is as follows: Figure 7 As shown in the figure, 395cm -1 and 151cm -1 It is the vibration peak of the S-Se bond.

[0074] The data from the infrared and Raman spectra strongly demonstrate that the present invention successfully synthesized a product with the target structure.

[0075] The infrared and Raman spectra of the dibutyl dithiophosphate selenium prepared in other embodiments are similar to those in Example 1, and will not be described again here.

[0076] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A dibutyl dithiophosphate selenium accelerator for resisting reversion rubber, characterized in that, The structural formula is as follows: 。 2. The preparation method of the anti-reversion rubber accelerator dibutyl dithiophosphate selenium according to claim 1, characterized in that, Includes the following steps: The preparation of the anti-reversion rubber accelerator dibutyl dithiophosphate selenium includes the following steps: Hydrochloric acid solution was added to selenium dioxide solution under stirring conditions to obtain a mixed solution; then the mixed solution was added dropwise to dibutyl dithiophosphate ammonium solution, and the reaction was stirred after the addition was completed; after the stirring reaction was completed, the solution was separated, washed, and dried to obtain the anti-reversion rubber accelerator dibutyl dithiophosphate selenium; the molar ratio of selenium dioxide, hydrochloric acid, and dibutyl dithiophosphate ammonium was 1:4-4.5:4-4.5; the volume ratio of selenium dioxide solution to dibutyl dithiophosphate ammonium solution was 1:10-15; the stirring rate of the stirring reaction was 400-600 rpm, the stirring temperature was 2-10℃, and the stirring time was 2-4 h.

3. The preparation method of the anti-reversion rubber accelerator dibutyl dithiophosphate selenium according to claim 2, characterized in that: The solvent for the selenium dioxide solution is deionized water with a concentration of 0.10–0.13 g / ml.

4. The preparation method of the anti-reversion rubber accelerator dibutyl dithiophosphate selenium according to claim 2, characterized in that: The solvent for the dibutyldithiophosphate ammonium solution is deionized water with a concentration of 0.06–0.11 g / ml.

5. The preparation method of the anti-reversion rubber accelerator dibutyl dithiophosphate selenium according to claim 2, characterized in that: The hydrochloric acid solution contains 35% to 38% hydrochloric acid by mass.

6. The preparation method of the anti-reversion rubber accelerator dibutyl dithiophosphate selenium according to claim 2, characterized in that: The mixed solution is added drop by drop.

7. The application of the anti-reversion rubber accelerator dibutyl dithiophosphate selenium as described in claim 1 in the preparation of rubber.

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