Supported anti-sulfur reducing agent and method for preparing the same

Abstract

This invention discloses a supported anti-sulfurization reducing agent and its preparation method, relating to the technical field of rubber additives. A supported anti-sulfurization reducing agent includes an adhesive layer and an inner capsule. The adhesive layer is formed by blending a carrier rubber and a fatty acid salt. The inner capsule includes a core material and an inner capsule wall. The core material is the anti-sulfurization reducing agent, while the inner capsule wall is formed by reacting and curing an amino-modified liquid isoprene rubber and a urea-formaldehyde prepolymer. This application, by using microencapsulation, prepares an anti-sulfurization reducing agent with a double-layered supported structure. This not only effectively improves the problems of poor compatibility and difficult dispersion of pure anti-sulfurization reducing agents in rubber compounds, but also effectively protects the active ingredients, which is beneficial for improving the actual utilization rate of the anti-sulfurization reducing agent, reducing the amount of anti-sulfurization reducing agent added, and thus reducing the production cost of rubber products.

Description

Technical Field

[0001] This invention relates to the technical field of rubber additives, and in particular to a supported anti-sulfurization reducing agent and its preparation method. Background Technology

[0002] In the rubber industry, anti-vulcanization reducing agents are key additives for improving the vulcanization quality and extending the service life of diene rubber products. With the widespread use of rubber products in fields such as automobile tires and industrial seals, the industry's performance requirements for rubber products are becoming increasingly stringent, leading to higher standards for the performance, application effectiveness, and overall cost of anti-vulcanization reducing agents.

[0003] Currently, conventional techniques for addressing issues like anti-sulfurization during the vulcanization process of diene rubber systems often employ pure anti-sulfurization reducing agents, such as directly adding pure 1,3-bis(citronellylimide methyl)benzene to the rubber compound. While this method can alleviate the adverse reactions of vulcanization reduction to some extent, its application still has significant limitations. Specifically, taking 1,3-bis(citronellylimide methyl)benzene as an example, pure anti-sulfurization reducing agents are generally expensive, and they are difficult to disperse uniformly in the rubber compound, thus failing to fully realize their anti-sulfurization reducing function. Furthermore, this substance has an irritating odor, posing a potential impact on the production environment and human health, which is inconsistent with the trend of green production. In addition, the actual utilization rate of pure additives is low, further leading to resource waste and increased costs. Therefore, developing a low-cost, easily dispersible, environmentally friendly, and highly efficient anti-sulfurization reducing agent is of significant practical importance and application value for the rubber processing industry. Summary of the Invention

[0004] In order to improve the dispersion effect of anti-vulcanization reducing agents in diene rubber systems and increase their actual utilization rate, thereby reducing the production cost of rubber products and improving their performance, this application provides a supported anti-vulcanization reducing agent and its preparation method.

[0005] Firstly, the supported anti-sulfurization reducing agent provided in this application adopts the following technical solution: A loaded anti-sulfurization reducing agent includes an adhesive layer and an inner capsule. The adhesive layer is formed by blending a carrier rubber and a fatty acid salt. The adhesive layer is used to bond and encapsulate the inner capsule and is then mixed and granulated to form a loaded granule. The inner capsule includes a core material and an inner capsule wall. The core material is an anti-sulfurization reducing agent, and the inner capsule wall is formed by reaction curing of an amino-modified liquid isoprene rubber and a urea-formaldehyde prepolymer.

[0006] By employing the above-mentioned technical solution, an anti-vulcanization reducing agent is prepared as a core material in a microencapsulation manner. Combined with an adhesive layer composed of carrier rubber and fatty acid salts, a supported anti-vulcanization reducing agent with a double-layer loading structure is obtained. This double-layer loading structure not only effectively improves the poor compatibility and dispersion difficulties of pure anti-vulcanization reducing agents in rubber compounds, but also effectively protects the effective components of the anti-vulcanization reducing agent, allowing it to function continuously and stably during the vulcanization process. This improves the actual utilization rate of the anti-vulcanization reducing agent, reduces the amount of anti-vulcanization reducing agent added, and lowers the production cost of rubber products. Furthermore, the fatty acid salts in the adhesive layer not only activate the vulcanization accelerator through reaction, accelerating the vulcanization reaction to a certain extent, but also synergistically increase the crosslinking density with the carrier rubber, which is beneficial for further optimizing the mechanical properties of the rubber.

[0007] Optionally, the preparation method of the amination-modified liquid isoprene rubber includes the following steps: A1. Dissolve carboxylated liquid isoprene rubber in an organic solvent, add dimethylformamide, and then slowly add thionyl chloride dropwise under an inert atmosphere while stirring continuously. After the addition is complete, heat to 40-45℃, stir continuously and reflux for 8-12 hours. After the reaction is complete, distill under reduced pressure to obtain acyl chloride liquid isoprene rubber. A2. Dissolve the acyl chloride liquid isoprene rubber again in an organic solvent, add excess anhydrous ethylenediamine, stir continuously for at least 12 hours, and control the temperature during the reaction to not exceed 35°C. After the reaction is completed, distill under reduced pressure to obtain the amination-modified liquid isoprene rubber.

[0008] By adopting the above technical solution, amino groups can be effectively grafted onto the ends of the liquid isoprene rubber, thereby providing stable active sites for subsequent chemical bonding with the urea-formaldehyde prepolymer. Furthermore, introducing the amino-modified liquid isoprene rubber prepared above helps improve the compatibility between the inner capsule wall and the carrier rubber, and allows the inner capsule to be uniformly and stably dispersed in the adhesive layer.

[0009] Optionally, in A1, the mass of the dimethylformamide is 0.5-1% of the mass of the carboxylated liquid isoprene rubber; the molar ratio of the carboxyl groups to thionyl chloride in the carboxylated liquid isoprene rubber is 1:(2.5-4).

[0010] By adopting the above technical solution, it is beneficial to ensure that the carboxyl groups in the carboxylated liquid isoprene rubber are completely converted into acyl chloride groups. While improving the modification efficiency, it also ensures that the reactivity of the aminolated liquid isoprene rubber is uniform and the modification stability is high. In addition, it is beneficial to prevent the waste of raw materials and the increase in the burden of subsequent distillation removal processes.

[0011] Optionally, the method for preparing the urea-formaldehyde prepolymer includes the following steps: Take urea and formaldehyde aqueous solution, mix them thoroughly, adjust the pH to 8.5-9, slowly heat to 48-53℃, and stir the reaction at a constant temperature. After the reaction is completed, quickly cool to below 10℃ to obtain urea-formaldehyde prepolymer. The molar ratio of urea to formaldehyde is 1:(1.5-2).

[0012] By adopting the above technical solution, the alkaline environment and rapid cooling process conditions can effectively inhibit the polycondensation of urea-formaldehyde prepolymer during the reaction process, while also ensuring the fluidity, reactivity and molecular weight uniformity of urea-formaldehyde prepolymer, which is beneficial to obtaining highly hydroxymethylated linear urea-formaldehyde prepolymer.

[0013] Optionally, the method for preparing the inner capsule includes the following steps: B1. The anti-sulfurization reducing agent and the amino-modified liquid isoprene rubber are added to an organic solvent and ultrasonically treated to fully dissolve and disperse them to obtain an oil phase material; the urea-formaldehyde prepolymer is diluted with deionized water, stirred thoroughly, and the pH value is adjusted to 8-8.5 to obtain an aqueous phase material; B2. Weigh appropriate amounts of the oil phase and the aqueous phase according to the proportions. Add an emulsifier to the aqueous phase. Then, under high-speed shearing, drop the oil phase into the aqueous phase. During the drop addition, keep the temperature no higher than 30°C. After the drop addition is completed, continue high-speed shearing for 20-30 minutes while maintaining the stirring speed. Adjust the pH value to 5-5.5, add ammonium persulfate, and then heat to 63-68°C and stir slowly for 1-2 hours. Then, heat to 73-75°C and continue stirring for 20-30 minutes. After the reaction is completed, allow it to cool naturally to room temperature, filter, wash, and vacuum dry to obtain the inner capsule.

[0014] By adopting the above technical solution, it is beneficial to obtain inner capsules with high coverage and uniform particle size.

[0015] Optionally, in B1, the content of the anti-sulfurization reducing agent in the oil phase is 10-15 wt%, and the mass ratio of the anti-sulfurization reducing agent to the amino-modified liquid isoprene rubber is 1:(0.1-0.3); the effective content of the urea-formaldehyde prepolymer in the aqueous phase is 1-1.5 wt%. In B2, the mass ratio of the oil phase to the aqueous phase is 1:(2-3), the amount of emulsifier added is 4-6% of the mass of the oil phase, and the mass of the ammonium persulfate is 0.06%-0.1% of the mass of the aqueous phase.

[0016] Optionally, the emulsifier is a composition of polyvinyl alcohol and hydroxyethyl cellulose, and the mass ratio of polyvinyl alcohol to hydroxyethyl cellulose is 1:(0.2-0.6).

[0017] By adopting the above technical solution, polyvinyl alcohol can form an adsorption film on the surface of oil phase droplets to prevent droplet aggregation, while hydroxyethyl cellulose can increase the viscosity of the aqueous phase and further stabilize the emulsion system. This helps to ensure that the oil phase material forms small, uniform, and highly stable emulsion droplets in the aqueous phase material, and forms inner capsules with uniform particle size, high sphericity, and intact capsule walls.

[0018] Optionally, the carrier rubber is one of butadiene rubber and styrene-butadiene rubber, and the fatty acid salt is zinc fatty acid.

[0019] By adopting the above technical solutions, both butadiene rubber and styrene-butadiene rubber exhibit good compatibility with diene rubber systems, effectively ensuring the uniform dispersion of the supported anti-vulcanization reducing agent in the applied rubber compound, preventing phase separation and additive agglomeration, and improving the processing adaptability of the supported anti-vulcanization reducing agent. Zinc fatty acid not only improves the adhesion and flexibility of the adhesive layer, ensuring effective coating of the core material, but also acts as an activator to activate the vulcanization accelerator, accelerating the vulcanization reaction and synergistically increasing the crosslinking density of the carrier rubber, further optimizing the mechanical properties of the rubber. Furthermore, it can improve the mixing and processing performance of the carrier rubber and the applied rubber compound to a certain extent, reducing melt viscosity, which is beneficial to improving the effectiveness of the supported anti-vulcanization reducing agent.

[0020] Secondly, the preparation method of the supported anti-sulfurization reducing agent provided in this application adopts the following technical solution: A method for preparing a supported anti-sulfurization reducing agent includes the following steps: The carrier rubber, fatty acid salt and inner capsule are mixed in proportion and then placed in an extruder for extrusion granulation. During the extrusion process, the temperature of the screw and the extrusion die is controlled within the range of 55-70℃ to obtain the loaded anti-sulfurization reducing agent.

[0021] By adopting the above technical solution, the preparation method is simple, mild, and easy to industrialize. Moreover, no toxic or harmful solvents or additives are required during the preparation process, which meets the requirements of green chemistry and sustainable development.

[0022] Optionally, the mass ratio of the carrier rubber, the fatty acid salt, and the inner capsule is (2-3):(2.5-3):(4.5-5).

[0023] By adopting the above technical solution, the optimal balance of core activity, binding coating and functional synergy is achieved, so that the supported anti-sulfurization reducing agent has both good strength and fluidity, is uniformly dispersed in the rubber system, ensures the consistent performance of all parts of the rubber product, and maximizes the synergistic anti-sulfurization reducing effect of each component.

[0024] In summary, the technical solution of this application includes at least one of the following beneficial effects: By using microcapsules to prepare inner capsules with anti-sulfurization reducing agents as core materials, and combining them with an adhesive layer composed of carrier rubber and fatty acid salts, not only can the problems of poor compatibility and difficult dispersion of pure anti-sulfurization reducing agents in rubber compounds be effectively improved, but the effective components of anti-sulfurization reducing agents can also be effectively protected. This is conducive to improving the actual utilization rate of anti-sulfurization reducing agents, reducing the amount of anti-sulfurization reducing agents added, and thus reducing the production cost of rubber products.

[0025] By using a specific carrier rubber in combination with fatty acid salts as a binder layer, it is not only beneficial to improve the processing compatibility of the supported anti-vulcanization reducing agent, but also the zinc fatty acid can activate the vulcanization accelerator through reaction, thereby accelerating the vulcanization reaction to a certain extent. At the same time, it can synergistically improve the crosslinking density with the carrier rubber, which is beneficial to further optimize the mechanical properties of the rubber. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of a supported anti-sulfurization reducing agent in Embodiment 1 of this application.

[0027] Explanation of reference numerals in the attached figures: 1. Adhesive layer; 2. Inner capsule; 21. Core material; 22. Inner capsule wall. Detailed Implementation

[0028] The present application will be further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0029] The carboxylated liquid isoprene rubber was specifically purchased from Kuraray, Japan, with the brand name LIR-410.

[0030] The zinc fatty acid was specifically purchased from Greenlink (Jining) Chemical Technology. Preparation Example

[0031]

Preparation Example 1-1

[0032] In this preparation example, the amount of dimethylamide added is 1% of the mass of the carboxylated liquid isoprene rubber, and the molar ratio of carboxyl groups to thionyl chloride in the carboxylated liquid isoprene rubber is 1:2.5.

[0033]

Preparation Examples 1-2

[0034] In this preparation example, the amount of dimethylamide added is 0.5% of the mass of the carboxylated liquid isoprene rubber, and the molar ratio of carboxyl groups to thionyl chloride in the carboxylated liquid isoprene rubber is 1:4.

[0035]

Preparation Example 2-1

[0036]

Preparation Example 2-2

[0037]

Preparation Example 3-1

[0038] In this preparation example, the anti-sulfurization reducing agent is specifically 1,3-bis(citronellylimidemethyl)benzene, the amino-modified liquid isoprene rubber is prepared from [Preparation Example 1-1], and the urea-formaldehyde prepolymer is prepared from [Preparation Example 2-1].

[0039] A method for preparing an inner capsule 2 includes the following steps: B1. Add 1 kg of anti-sulfurization reducing agent and 0.1 kg of amination-modified liquid isoprene rubber to anhydrous tetrahydrofuran, and sonicate to fully dissolve and disperse them to obtain an oil phase material with an anti-sulfurization reducing agent content of 10 wt%. Dilute the urea-formaldehyde prepolymer with deionized water to obtain a prepolymer dilution solution with a urea-formaldehyde prepolymer content of 1 wt%. Stir thoroughly and adjust the pH value to 8.5 to obtain an aqueous phase material. B2. Weigh 10 kg of oil phase material and 20 kg of aqueous phase material respectively. Add 0.4 kg of emulsifier to the aqueous phase material. Then, under high-speed shearing at 12000 rpm, drop the oil phase material into the aqueous phase material. Keep the temperature not higher than 30℃ during the drop addition process. After the drop addition is completed, maintain the rotation speed and shear at high speed for 30 min to obtain a dispersed emulsion. B3. Adjust the pH of the dispersion emulsion to 5.5, add 0.02 kg of ammonium persulfate, then heat to 63°C and stir at 500 rpm for 2 hours. Then heat to 73°C and continue stirring for 30 minutes. After the reaction is complete, cool naturally to room temperature, filter under reduced pressure, wash, and vacuum dry to obtain inner capsule 2.

[0040] In this preparation example B2, the emulsifier is specifically a composition of polyvinyl alcohol and hydroxyethyl cellulose, and the mass ratio of polyvinyl alcohol to hydroxyethyl cellulose is 1:0.6, that is, it includes 0.25 kg of polyvinyl alcohol and 0.15 kg of hydroxyethyl cellulose.

[0041]

Preparation Example 3-2

[0042] In this preparation example, the inner bladder wall 22 is formed by reaction curing of an amino-modified liquid isoprene rubber and a urea-formaldehyde prepolymer, wherein the amino-modified liquid isoprene rubber is prepared according to [Preparation Example 1-2] and the urea-formaldehyde prepolymer is prepared according to [Preparation Example 2-2].

[0043] A method for preparing an inner capsule 2 includes the following steps: B1. Add 1.5 kg of anti-sulfurization reducing agent and 0.3 kg of amination-modified liquid isoprene rubber to anhydrous tetrahydrofuran, and sonicate to fully dissolve and disperse them to obtain an oil phase material with an anti-sulfurization reducing agent content of 15 wt%. Dilute the urea-formaldehyde prepolymer with deionized water to obtain a prepolymer dilution solution with a urea-formaldehyde prepolymer content of 1.5 wt%. Stir thoroughly and adjust the pH value to 8 to obtain an aqueous phase material. B2. Weigh 10 kg of oil phase material and 30 kg of aqueous phase material respectively. Add 0.6 kg of emulsifier to the aqueous phase material. Then, under high-speed shearing at 10000 rpm, drop the oil phase material into the aqueous phase material. Keep the temperature not higher than 30℃ during the drop addition process. After the drop addition is completed, maintain the rotation speed and shear at high speed for 30 min to obtain a dispersed emulsion. B3. Adjust the pH of the dispersion emulsion to 5, add 0.018 kg of ammonium persulfate, then heat to 68°C and stir at 500 rpm for 1 hour. Then heat to 75°C and continue stirring for 20 minutes. After the reaction is complete, cool naturally to room temperature, filter under reduced pressure, wash, and vacuum dry to obtain inner capsule 2.

[0044] In this preparation example B2, the emulsifier is specifically a composition of polyvinyl alcohol and hydroxyethyl cellulose, and the mass ratio of polyvinyl alcohol to hydroxyethyl cellulose is 1:0.2, that is, it includes 0.5 kg of polyvinyl alcohol and 0.1 kg of hydroxyethyl cellulose.

[0045]

Preparation Example 3-3

[0046] In step B2 of the preparation method in this example, the mass ratio of the oil phase to the aqueous phase is 1:3.5, that is, 10 kg of oil phase and 35 kg of aqueous phase are weighed out for preparation. Meanwhile, in step B3 of the preparation method, 0.035 kg of ammonium persulfate is added.

[0047]

Preparation Examples 3-4

[0048] In step B2 of the preparation method in this example, the mass ratio of the oil phase to the aqueous phase is 1:5, that is, 10 kg of oil phase and 50 kg of aqueous phase are weighed out for preparation. Meanwhile, in step B3 of the preparation method, 0.05 kg of ammonium persulfate is added.

[0049]

Preparation Examples 3-5

[0050] In this preparation example, the inner capsule wall 22 is formed by the reaction curing of urea-formaldehyde prepolymer, wherein the urea-formaldehyde prepolymer is prepared by [Preparation Example 2-1].

[0051] A method for preparing an inner capsule 2 includes the following steps: B1. Add 1 kg of anti-sulfurization reducing agent to anhydrous tetrahydrofuran, and sonicate it to fully dissolve and disperse it, to obtain an oil phase material with an anti-sulfurization reducing agent content of 10 wt%; dilute the urea-formaldehyde prepolymer with deionized water to obtain a prepolymer dilution solution with a urea-formaldehyde prepolymer content of 1 wt%, stir thoroughly and adjust the pH value to 8.5 to obtain an aqueous phase material. B2. Weigh 10 kg of oil phase material and 20 kg of aqueous phase material respectively. Add 0.4 kg of emulsifier to the aqueous phase material. Then, under high-speed shearing at 12000 rpm, drop the oil phase material into the aqueous phase material. Keep the temperature not higher than 30℃ during the drop addition process. After the drop addition is completed, maintain the rotation speed and shear at high speed for 30 min to obtain a dispersed emulsion. B3. Adjust the pH of the dispersion emulsion to 5.5, add 0.02 kg of ammonium persulfate, then heat to 63°C and stir at 500 rpm for 2 hours. Then heat to 73°C and continue stirring for 30 minutes. After the reaction is complete, cool naturally to room temperature, filter under reduced pressure, wash, and vacuum dry to obtain inner capsule 2.

[0052] In this preparation example B2, the emulsifier is specifically a composition of polyvinyl alcohol and hydroxyethyl cellulose, and the mass ratio of polyvinyl alcohol to hydroxyethyl cellulose is 1:0.6, that is, it includes 0.25 kg of polyvinyl alcohol and 0.15 kg of hydroxyethyl cellulose. Example

[0053]

Example 1

[0054] In this embodiment, the supported anti-sulfurization reducing agent is formed by granulation of the following raw materials: 2kg carrier rubber, 3kg fatty acid salt and 5kg inner capsule 2.

[0055] The carrier rubber is cis-butadiene rubber, the fatty acid salt is specifically zinc fatty acid, and the inner capsule 2 is specifically prepared according to [Preparation Example 3-1].

[0056] A method for preparing a supported anti-sulfurization reducing agent includes the following steps: The carrier rubber, zinc fatty acid and inner capsule 2 are mixed thoroughly in a certain proportion beforehand. Then the mixture is added to a single screw extruder for extrusion granulation. During the extrusion process, the temperature of the screw and the extrusion die is controlled within the range of 70-85℃ to obtain the loaded anti-sulfurization reducing agent.

[0057]

Example 2

[0058] In this embodiment, the supported anti-sulfurization reducing agent is formed by granulation of the following raw materials: 3 kg of carrier rubber and 2.5 kg of fatty acid salt, 4.5 kg of inner capsule 2.

[0059] The carrier rubber is styrene-butadiene rubber, the fatty acid salt is specifically zinc fatty acid, and the inner capsule 2 is specifically prepared according to [Preparation Example 3-2].

[0060]

Example 3

[0061] In this embodiment, the inner capsule 2 is specifically prepared according to [Preparation Example 3-3].

[0062]

Example 4

[0063] In this embodiment, the inner capsule 2 is specifically prepared according to [Preparation Examples 3-4].

[0064]

Example 5

[0065] In this embodiment, the carrier rubber is specifically styrene-butadiene rubber. Comparative Example

[0066] Comparative Example 1 A supported anti-sulfurization reducing agent, which differs from [Example 1] in that it does not have an adhesive layer 1.

[0067] Comparative Example 2 A supported anti-sulfurization reducing agent, which differs from [Example 1] in that fatty acid salts are not added to the adhesive layer 1.

[0068] In this comparative example, a carrier rubber was used to replace the fatty acid salt in equal amounts.

[0069] Comparative Example 3 A supported anti-sulfurization reducing agent, which differs from [Example 1] in that the inner capsule 2 is different.

[0070] In this comparative example, the inner capsule 2 was specifically prepared according to [Preparation Examples 3-5]. Performance testing

[0071] Sample preparation: The ingredients are prepared according to the test formula in Table 1 below and used as the test object. The raw materials in Table 1 are all commonly used raw materials in the tire industry.

[0072] The supported anti-sulfurization reducing agent used in Test Examples 1-5 corresponds to the supported anti-sulfurization reducing agent prepared in Examples 1-5. The supported anti-sulfurization reducing agent used in Test Examples 6-8 corresponds to the supported anti-sulfurization reducing agent prepared in Comparative Examples 1-3. Test Examples 9-10 serve as blank control groups with added anti-sulfurization reducing agent, wherein the anti-sulfurization reducing agent is 1,3-bis(citronomidimethyl)benzene.

[0073] Table 1. Sample Formulation Table

[0074] 1. Vulcanization Curve Comparison: The above-mentioned sample formulations were mixed and vulcanized using a vulcanizer, and vulcanization curves for each sample formulation were obtained. Comparing the vulcanization curves, the longer the plateau period of the vulcanization curve and the slower the torque decrease, indicating that the rubber compound formulation has better resistance to vulcanization reduction. All recorded times are rounded to one decimal place; if less than 30 seconds, it is recorded as 0 minutes; if more than 30 seconds but less than 1 minute, it is recorded as 0.5 minutes.

[0075] 2. Tensile strength: The test was conducted in accordance with GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber, and the tensile strength (MPa) of the vulcanized rubber was recorded after vulcanization at 140℃ for 40 min, 60 min, 80 min and 100 min.

[0076] Table 2 Performance test data of supported anti-sulfurization reducing agents

[0077] Based on test examples 1-10 and Table 2, it can be seen that by preparing an inner capsule 2 with an anti-sulfurization reducing agent as the core material 21 in the form of microcapsules, and combining it with an adhesive layer 1 composed of carrier rubber and fatty acid salts, a loaded anti-sulfurization reducing agent with a double-layer load structure is obtained. This not only improves the effect of the anti-sulfurization reducing agent, but also improves the mechanical properties of the rubber compound to a certain extent.

[0078] Specifically, as can be seen from Test Example 1 and Test Examples 9-10 and their test data, the loaded anti-vulcanization reducing agent used in Test Example 1, which contains only about 35-45% of the effective anti-vulcanization reducing agent, is significantly different from Test Example 9, which uses the same loaded anti-vulcanization reducing agent dosage and is made of pure 100% anti-vulcanization reducing agent, and Test Example 10, which uses the same effective amount and is made of pure 100% anti-vulcanization reducing agent. The vulcanization curve formed in Test Example 1 is close to that of Test Example 9, and even the plateau period is slightly longer than that of Test Example 9. This means that the loaded anti-vulcanization reducing agent prepared in Example 1 can effectively improve the problem of difficult dispersion and low practical utilization of pure anti-vulcanization reducing agent in rubber compounds, which is conducive to reducing the amount of anti-vulcanization reducing agent used and reducing the production cost of rubber products.

[0079] As can be seen from Test Examples 1 and 6-7 and their test data, since Test Example 6 uses a supported anti-vulcanization reducing agent prepared from Comparative Example 1, its outer layer lacks the adhesive layer 1 for further coating. Therefore, under the same addition amount, the effective component of the supported anti-vulcanization reducing agent added in Test Example 6 is significantly higher than that in Test Example 1. However, the plateau time of the vulcanization curve in Test Example 6 is significantly shortened, and the mechanical properties of the vulcanized rubber are also inferior to those in Test Example 1. This may be because the adhesive layer 1 is mainly prepared from carrier rubber and fatty acid salts. In the formulation of natural rubber compounds, the bonding and coating of butadiene rubber and fatty acid salts can significantly improve the compatibility and dispersibility between the inner capsule 2 and the rubber compound. However, since the inner shell of the inner capsule 2 is formed by the reaction of amino-modified liquid isoprene rubber and urea-formaldehyde prepolymer, without the adhesive coating of the adhesive layer 1, the compatibility and dispersibility between the inner capsule 2 and the rubber compound are poor. This not only leads to a slightly worse anti-vulcanization reducing effect, but also affects the vulcanization of the rubber compound. Secondly, the zinc fatty acid in the adhesive layer 1 can generate zinc soap through subsequent reactions, which can activate the vulcanization accelerator and accelerate the vulcanization reaction to a certain extent. This not only shortens the T90 time but also works with the carrier rubber to increase the crosslinking density and further optimize the mechanical properties of the rubber.

[0080] As can be seen from Test Examples 1 and 8 and their test data, the actual performance of the loaded anti-sulfurization reducing agent prepared by simply using urea-formaldehyde prepolymer as the main component of the inner shell is not good. This may be because the inner shell formed by the monourea-formaldehyde prepolymer also has problems of low compatibility and difficult bonding with the carrier rubber. As a result, the adhesive layer 1 cannot fully combine with the inner shell 2 during the granulation process, and it is difficult to uniformly and stably disperse the inner shell 2 in the rubber compound through the adhesive layer 1.

[0081] As shown in Test Examples 1 and 3-4 and their test data, during the preparation of the inner capsule 2, an increase in the proportion of the aqueous phase material, i.e., an increase in the content of urea-formaldehyde prepolymer, leads to a weakening of the actual performance of the subsequently prepared supported anti-sulfurization reducing agent. This may be because as the proportion of the aqueous phase material increases, the inner capsule wall 22 becomes thicker. While this is beneficial for improving the stability and protective properties of the inner capsule 2, it affects the actual proportion of the anti-sulfurization reducing agent. Therefore, with the same amount of addition, the supported anti-sulfurization reducing agent with a thicker inner capsule wall 22 will have a slightly worse actual performance.

[0082] As can be seen from Test Example 1 and Test Example 5 and their test data, when the carrier rubber of the supported anti-vulcanization reducing agent is styrene-butadiene rubber, it is beneficial to further improve the mechanical strength of the rubber compound.

[0083] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A supported anti-sulfurization reducing agent, characterized in that: It includes an adhesive layer (1) and an inner capsule (2). The adhesive layer (1) is formed by blending a carrier rubber and a fatty acid salt. The adhesive layer (1) is used to bond and coat the inner capsule (2) and form a loaded granule by mixing and granulation. The inner capsule (2) includes a core material (21) and an inner capsule wall (22). The core material (21) is an anti-sulfurization reducing agent, and the inner capsule wall (22) is formed by reaction curing of an amino-modified liquid isoprene rubber and a urea-formaldehyde prepolymer.

2. The supported anti-sulfurization reducing agent according to claim 1, characterized in that: The preparation method of the amino-modified liquid isoprene rubber includes the following steps: A1. Dissolve carboxylated liquid isoprene rubber in an organic solvent, add dimethylformamide, and then add thionyl chloride dropwise under an inert atmosphere while continuously stirring. After the addition is complete, heat to 40-45℃, continuously stir and reflux for 8-12 hours. After the reaction is complete, distill under reduced pressure to obtain acyl chloride liquid isoprene rubber. A2. Dissolve the acyl chloride liquid isoprene rubber again in an organic solvent, add ethylenediamine, and stir continuously for at least 12 hours, while controlling the temperature to not exceed 35°C during the reaction. After the reaction is completed, distill under reduced pressure to obtain the amination-modified liquid isoprene rubber.

3. The supported anti-sulfurization reducing agent according to claim 2, characterized in that: In A1, the mass of the dimethylformamide is 0.5-1% of the mass of the carboxylated liquid isoprene rubber; the molar ratio of the carboxyl group to thionyl chloride in the carboxylated liquid isoprene rubber is 1:(2.5-4).

4. The supported anti-sulfurization reducing agent according to claim 1, characterized in that: The preparation method of the urea-formaldehyde prepolymer includes the following steps: Take urea and formaldehyde aqueous solution, mix them thoroughly, adjust the pH to 8.5-9, slowly heat to 48-53℃, and stir the reaction at a constant temperature. After the reaction is completed, quickly cool to below 10℃ to obtain urea-formaldehyde prepolymer. The molar ratio of urea to formaldehyde is 1:(1.5-2).

5. The supported anti-sulfurization reducing agent according to claim 1, characterized in that: The method for preparing the inner capsule (2) includes the following steps: B1. The anti-sulfurization reducing agent and the amino-modified liquid isoprene rubber are added to an organic solvent and ultrasonically treated to fully dissolve and disperse them to obtain an oil phase material; the urea-formaldehyde prepolymer is diluted with deionized water, stirred thoroughly, and the pH value is adjusted to 8-8.5 to obtain an aqueous phase material; B2. Weigh appropriate amounts of the oil phase material and the aqueous phase material according to the proportion. Add emulsifier to the aqueous phase material. Then, under high-speed shear, drop the oil phase material into the aqueous phase material. During the drop addition, keep the temperature not higher than 30°C. After the drop addition is completed, continue high-speed shearing for 20-30 minutes while maintaining the stirring speed. Adjust the pH value to 5-5.5, add ammonium persulfate, and then heat to 63-68°C and stir slowly for 1-2 hours. Then heat to 73-75°C and continue stirring for 20-30 minutes. After the reaction is completed, cool naturally to room temperature, filter, wash, and vacuum dry to obtain the inner capsule (2).

6. The supported anti-sulfurization reducing agent according to claim 5, characterized in that: In B1, the content of the anti-sulfurization reducing agent in the oil phase is 10-15 wt%, and the mass ratio of the anti-sulfurization reducing agent to the amino-modified liquid isoprene rubber is 1:(0.1-0.3); the effective content of the urea-formaldehyde prepolymer in the aqueous phase is 1-1.5 wt%. In B2, the mass ratio of the oil phase to the aqueous phase is 1:(2-3), the amount of emulsifier added is 4-6% of the mass of the oil phase, and the mass of the ammonium persulfate is 0.06%-0.1% of the mass of the aqueous phase.

7. The supported anti-sulfurization reducing agent according to claim 6, characterized in that: The emulsifier is a composition of polyvinyl alcohol and hydroxyethyl cellulose, and the mass ratio of polyvinyl alcohol to hydroxyethyl cellulose is 1:(0.2-0.6).

8. The supported anti-sulfurization reducing agent according to claim 1, characterized in that: The carrier rubber is one of butadiene rubber and styrene-butadiene rubber, and the fatty acid salt is zinc fatty acid.

9. A method for preparing a supported anti-sulfurization reducing agent, used to prepare the supported anti-sulfurization reducing agent as described in any one of claims 1-8, characterized in that, Includes the following steps: The carrier rubber, fatty acid salt and inner capsule (2) are mixed in proportion and then placed in an extruder for extrusion granulation. During the extrusion process, the temperature of the screw and the extrusion die is controlled within the range of 70-85℃ to obtain the loaded anti-sulfurization reducing agent.

10. The method for preparing a supported anti-sulfurization reducing agent according to claim 9, characterized in that: The mass ratio of the carrier rubber, the fatty acid salt, and the inner capsule (2) is (2-3):(2.5-3):(4.5-5).

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