A high styrene reinforced rubber material and a method of making the same

Abstract

The application discloses a high-styrene reinforced rubber material and a preparation method thereof. The high-styrene reinforced rubber material comprises a rubber matrix and a reinforcing agent, wherein the reinforcing agent comprises high-styrene, the high-styrene is coated with a coating substance, and the coating substance comprises styrene-butadiene rubber. The high-styrene is coated with the functionalized rubber layer through pre-processing to form a core-shell structure, and then is mixed with the rubber material, so that the compatibility and dispersibility between the high-styrene and the rubber matrix are improved, and the mechanical properties and the creep resistance are improved.

Description

Technical Field

[0001] This invention belongs to the field of rubber materials, and particularly relates to a rubber material and its preparation method. Background Technology

[0002] Natural rubber (NR) possesses excellent airtightness, electrical insulation, and abrasion resistance, and is widely used in tires, seals, and conveyor belts. Styrene-butadiene rubber (SBR), also known as polystyrene-butadiene copolymer, has physical properties, processing properties, and product performance similar to natural rubber. Some properties, such as abrasion resistance, heat resistance, aging resistance, and vulcanization speed, are even superior to natural rubber. It can be used in combination with natural rubber and various synthetic rubbers, and is widely used in the production of tires, belts, hoses, wires and cables, medical devices, and various rubber products. It is one of the most widely used general-purpose synthetic rubber varieties. During the use of rubber materials, carbon black or silica is often added for reinforcement. However, silica and carbon black materials are prone to environmental pollution and are harmful to human health. Therefore, developing new reinforcing alternatives is of great significance.

[0003] High-styrene resin is an excellent reinforcing filler. It is a non-polar polymer copolymerized from high-content styrene and butadiene monomers, with a styrene content exceeding 70% in its molecular chain. It possesses advantages such as high hardness, good aging resistance, and high mechanical strength. Due to its high styrene content, high-styrene resin exhibits a certain degree of rigidity and hardness. However, when used as a rubber reinforcing agent, it has poor interfacial compatibility with natural rubber, making it difficult to achieve a dispersing and reinforcing effect within a natural rubber matrix. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a high-styrene-reinforced rubber material with good dispersion and reinforcement effect and its preparation method.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] A high-styrene-reinforced rubber material includes a rubber matrix and a reinforcing agent, wherein the reinforcing agent comprises high-styrene, and the surface of the high-styrene is coated with a coating material, wherein the coating material comprises styrene-butadiene rubber. That is, the reinforcing agent is high-styrene coated with a coating material.

[0007] In the above-mentioned high-styrene-reinforced rubber materials, preferably, the weight ratio of the high-styrene to the coating material in the reinforcing agent is (10-50):(30-90).

[0008] In the above-mentioned high-styrene-reinforced rubber materials, preferably, the coating material is a mixture of styrene-butadiene rubber and natural rubber, and the weight ratio of the styrene-butadiene rubber to the natural rubber is (1-2):(0.5-1).

[0009] In the above-mentioned high-styrene-reinforced rubber materials, preferably, the rubber matrix includes natural rubber and / or styrene-butadiene rubber.

[0010] In the above-mentioned high-styrene-reinforced rubber materials, preferably, the weight ratio of the rubber matrix to the reinforcing agent is (100-130):(40-70).

[0011] As a general technical concept, the present invention also provides a method for preparing the above-mentioned high-styrene-reinforced rubber material, comprising the following steps: (1) Place the coating material in a mixer and add high styrene for mixing to obtain core-shell particles coated with high styrene; (2) The rubber matrix is ​​placed in an open mixing mill for plasticizing, and after being wrapped with rollers, the core-shell particles and additives are added and mixed to obtain a high-styrene-reinforced rubber material.

[0012] In the above preparation method, preferably, in step (1), during internal mixing, the mixing temperature is 110-130℃, the speed is first controlled at 5-15 rpm, internal mixing is performed for 1-5 min, and then the speed is increased to 17-35 rpm, and then mixed for 2-4 min.

[0013] In the above preparation method, preferably, in step (2), the additives include zinc oxide, stearic acid, polyethylene glycol, antioxidant 2246, sun-resistant whitening agent, vulcanization accelerator CZ, vulcanization accelerator DM and sulfur.

[0014] In the above preparation method, preferably, in step (2), the rubber matrix is ​​first placed in an open rubber mixing mill for plasticizing, the temperature is controlled at 30-80℃, and it is passed through the mill 1-5 times. After rolling, zinc oxide, stearic acid, polyethylene glycol, antioxidant 2246, sun-resistant whitening agent and core-shell particles are added and the rubber is turned 2-5 times. Then, vulcanization accelerator CZ, vulcanization accelerator DM and sulfur are added and the rubber is turned 2-5 times. After passing through the mill 1-5 times, the rubber is finally discharged and left to stand for 24-36 hours.

[0015] High-styrene (HS) resin is a polymer obtained by emulsion copolymerization of styrene and butadiene. It shares certain similarities in molecular structure with diene rubbers such as natural rubber (NR) and styrene-butadiene rubber (SBR), and HS, being a "hard rubber" with high hardness and stiffness, holds promise as a reinforcing component for rubber materials. However, when HS is used directly for rubber reinforcement, it still suffers from insufficient interfacial compatibility with the rubber matrix, and is prone to agglomeration and interfacial defects. Therefore, this invention employs styrene-butadiene rubber to pre-coat HS before using it to reinforce a natural rubber matrix. In this process, HS acts as the core, utilizing its good compatibility with the styrene segments in SBR to ensure a tight bond between HS and the SBR coating layer. Simultaneously, the SBR coating layer serves as an intermediate transition layer, forming a more favorable interfacial transition structure with the natural rubber matrix on its outer side, thus constructing a layered interfacial system of "HS core - SBR intermediate layer - NR outer layer". This structural design effectively improves the dispersibility and interfacial bonding ability of HS in natural rubber, thereby achieving more effective reinforcement of natural rubber.

[0016] In a more preferred embodiment, for the specific reinforcing particle high-styrene (HS), the coating material of this invention uses a mixture of styrene-butadiene rubber (SBR) and natural rubber. This mixture can more effectively transfer and disperse stress, reduce stress concentration at the coating interface, and thus improve the mechanical properties and durability of the material. Furthermore, using a mixture of SBR and natural rubber as the coating material improves processability and structural stability. During the internal mixing and coating process, the viscosity and rheological properties of the mixed rubber compound may more easily form a complete and continuous coating layer. In subsequent mixing with the rubber matrix, it can also better maintain the integrity of the "core-shell structure" and prevent HS exposure. The coating material and the internal mixing method of coating modification have better compatibility. In addition, using a mixture of SBR and natural rubber as the coating material is more suitable for situations where the rubber matrix uses natural rubber and SBR, which is beneficial for optimizing the compatibility of the inner and outer phases.

[0017] In a more preferred embodiment, this invention proposes for the first time to employ a intensive mixing method for hard coating of HS (high-styrene) particles, achieving strong and uniform coating. Under shear force and temperature, the coating material (SBR / NR mixture) is forcibly kneaded and deformed, tightly wrapping around the surface of the HS particles to form a complete and firmly bonded "core-shell" structure, effectively preventing the HS from being exposed and agglomerated in subsequent processing. Simultaneously, it promotes interfacial diffusion and physical entanglement: the high temperature (110-130℃) of intensive mixing enhances the mobility of the polymer chain segments in the coating layer, facilitating their penetration and diffusion into the micropores or gaps on the HS surface, while also forming stronger physical entanglement with the HS molecular chains, significantly improving interfacial bonding. Furthermore, this coating method is highly efficient and suitable for industrialization. This method combines the "coating" and "mixing" processes into one, completed directly in an intensive mixer, resulting in a short process, high efficiency, and ease of scale-up production, offering significant advantages for industrial applications.

[0018] Compared with the prior art, the advantages of the present invention are as follows: This invention fully utilizes the inherent properties of the material. By pre-mixing, the styrene-butadiene rubber is first wetted and coated with the surface of high-styrene, allowing the high-styrene to enter the matrix in a more stable core-shell intermediate form. This significantly improves dispersibility and interfacial bonding. In other words, the functionalized rubber layer is pre-processed to coat the high-styrene, forming a core-shell structure. Then, it is mixed with the rubber material to improve the compatibility and dispersibility between the high-styrene and the rubber matrix, thereby improving mechanical properties and creep resistance. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 Optical microscope images of cross-sections of vulcanized rubber in Comparative Example 3 and Example 2.

[0021] Figure 2 Cross-sectional views of Comparative Example 1 (a), High-Styrene (b), Comparative Example 3 (gi), and Example 2 (cf) at different magnifications using scanning electron microscopes. Detailed Implementation

[0022] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0023] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0024] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0025] Example 1: A high-styrene-reinforced rubber material includes a rubber matrix and a reinforcing agent. The rubber matrix is ​​styrene-butadiene rubber (SBR), and the reinforcing agent is high-styrene coated with SBR. The preparation method of the rubber material includes the following steps: Place 30 parts of styrene-butadiene rubber in a mixer, add 10 parts of high styrene, mix at 120°C and 10 rpm for 2 minutes, increase the speed to 20 rpm, mix for another 3 minutes and then remove the premix to obtain SBR-coated HS core-shell particles. 70 parts of styrene-butadiene rubber were placed in an open mixing mill and plasticized at 60°C, passing through a thin pass 3 times. After wrapping the roller, add 5 parts zinc oxide, 2 parts stearic acid, 1.5 parts polyethylene glycol, 2 parts antioxidant 2246, 1 part sun-resistant whitening agent, and premix (i.e. SBR coated HS core-shell particles) and roll the rubber twice. Add 1 part of vulcanization accelerator CZ, 1.5 parts of vulcanization accelerator DM, and 3 parts of sulfur to the open mill. Turn the rubber twice, pass it through the thin mill three times, and finally discharge the rubber and let it stand for 24 hours before testing the vulcanization performance. The compound was molded on a 25T flat vulcanizing machine, and its tensile properties were tested. The results are shown in Table 1.

[0026] Example 2: Similar to Example 1, except that 30 parts of high styrene were added, and the test results are shown in Table 1.

[0027] Example 3: Similar to Example 1, except that 40 parts of high styrene were added, and the test results are shown in Table 1.

[0028] Example 4: A high-styrene-reinforced rubber material includes a rubber matrix and a reinforcing agent. The rubber matrix is ​​styrene-butadiene rubber and natural rubber, and the reinforcing agent is high-styrene-butadiene rubber coated with styrene-butadiene rubber. The preparation method of the rubber material includes the following steps: Place 30 parts of styrene-butadiene rubber in a mixer, add 30 parts of high styrene, mix at 120°C and 10 rpm for 1 minute, increase the speed to 20 rpm, mix for another 4 minutes and then remove the premix to obtain SBR-coated HS core-shell particles. 90 parts of styrene-butadiene rubber and 10 parts of natural rubber were placed in an open mixing mill and plasticized at 60°C, passing through a thin pass 3 times. After wrapping the roller, add 5 parts zinc oxide, 2 parts stearic acid, 1.5 parts polyethylene glycol, 2 parts antioxidant 2246, 1 part sun-resistant whitening agent, and the premixed material is rolled twice. Add 1 part of vulcanization accelerator CZ, 1.5 parts of vulcanization accelerator DM, and 3 parts of sulfur to the open mill. Turn the rubber twice, pass it through the thin mill three times, and finally discharge the rubber and let it stand for 24 hours before testing the vulcanization performance. The compound was molded on a 25T flat vulcanizing machine, and its tensile properties were tested. The results are shown in Table 1.

[0029] Example 5: Similar to Example 4, except that the rubber matrix consisted of 70 parts styrene-butadiene rubber and 30 parts natural rubber. The test results are shown in Table 1.

[0030] Example 6: Similar to Example 4, except that the rubber matrix consisted of 50 parts styrene-butadiene rubber and 50 parts natural rubber. The test results are shown in Table 1.

[0031] Example 7: A high-styrene-reinforced rubber material includes a rubber matrix and a reinforcing agent. The rubber matrix is ​​styrene-butadiene rubber and natural rubber, and the reinforcing agent is high-styrene coated with styrene-butadiene rubber and natural rubber. The preparation method of the rubber material includes the following steps: 20 parts of styrene-butadiene rubber were placed in a mixer, 30 parts of high styrene were added, and the mixture was premixed for 2 minutes. Then 10 parts of natural rubber were added. The mixing temperature was 120℃, the speed was 10 rpm, and the mixing was carried out for 2 minutes. The speed was increased to 20 rpm, and the mixture was mixed for another 4 minutes. The premix was then removed to obtain functionalized rubber layer coated HS core-shell particles. 50 parts of styrene-butadiene rubber and 50 parts of natural rubber were placed in an open mixing mill and plasticized at 60°C, passing through a thin pass 3 times. The other steps are the same as in Example 4, and the test results are shown in Table 1.

[0032] Comparative Example 1: A type of rubber, the preparation method of which is as follows: 100 parts of styrene-butadiene rubber were placed in an open mixing mill and plasticized at 60°C, passing through a thin pass 3 times. After wrapping the roller, add 5 parts zinc oxide, 2 parts stearic acid, 1.5 parts polyethylene glycol, 2 parts antioxidant 2246, and 1 part sun-resistant whitening agent, and then roll the rubber twice. Add 1.5 parts of vulcanization accelerator CZ, 1.5 parts of vulcanization accelerator DM, and 2 parts of sulfur to the open mill. Turn the rubber twice, pass it through the thin mill three times, and finally discharge the rubber and let it stand for 24 hours before testing the vulcanization performance. The compound was molded on a 25T flat vulcanizing machine, and its tensile properties were tested. The results are shown in Table 1.

[0033] Comparative Example 2: A type of rubber, the preparation method of which is as follows: 100 parts of styrene-butadiene rubber were placed in an open mixing mill and plasticized at 60°C, passing through a thin pass 3 times. After wrapping the roller, add 10 parts high styrene, 5 parts zinc oxide, 2 parts stearic acid, 1.5 parts polyethylene glycol, 2 parts antioxidant 2246, and 1 part sun-resistant whitening agent, and then roll the rubber twice. Add 1 part of vulcanization accelerator CZ, 1.5 parts of vulcanization accelerator DM, and 3 parts of sulfur to the open mill. Turn the rubber twice, pass it through the thin mill three times, and finally discharge the rubber and let it stand for 24 hours before testing the vulcanization performance. The compound was molded on a 25T flat vulcanizing machine, and its tensile properties were tested. The results are shown in Table 1.

[0034] Comparative Example 3: Similar to Comparative Example 2, but with the addition of 30 parts of high-styrene, the test results are shown in Table 1.

[0035] Comparative Example 4: Similar to Comparative Example 2, but with the addition of 40 parts of high-styrene, the test results are shown in Table 1.

[0036] Comparative Example 5: A high-styrene-reinforced rubber material includes a rubber matrix and a reinforcing agent. The rubber matrix is ​​styrene-butadiene rubber and natural rubber, and the reinforcing agent is high-styrene coated with styrene-butadiene rubber and natural rubber. The preparation method of the rubber material includes the following steps: 30 parts high styrene, 20 parts styrene-butadiene rubber and 10 parts natural rubber were premixed by open milling at 60°C and passed through a thin pass 3 times. The open mixing premix was plasticized with 50 parts styrene-butadiene rubber and 50 parts natural rubber in an open mixing mill at a temperature of 60°C, and passed through a thin pass 3 times. After wrapping the roller, add 5 parts zinc oxide, 2 parts stearic acid, 1.5 parts polyethylene glycol, 2 parts antioxidant 2246, and 1 part sun-resistant whitening agent, and then roll the rubber twice. Add 1.5 parts of vulcanization accelerator CZ, 1.5 parts of vulcanization accelerator DM, and 2 parts of sulfur to the open mill. Turn the rubber twice, pass it through the thin mill three times, and finally discharge the rubber and let it stand for 24 hours before testing the vulcanization performance. The compound was molded on a 25T flat vulcanizing machine, and its tensile properties were tested. The results are shown in Table 1.

[0037] In the above comparative examples and embodiments, the natural rubber mentioned above is the national standard No. 5 rubber; the zinc oxide and stearic acid mentioned above are nano-grade additives. In Table 1, scorch time, positive vulcanization time, maximum torque, and minimum torque are all vulcanization parameters: the vulcanization performance of different rubber compounds was tested using an MH-3000A rotorless vulcanizing apparatus. The test temperature was 160°C. o C. The test duration is 20 minutes, and the sample mass is 3-5g. Hardness: The hardness of the vulcanized rubber is tested using a Shore A hardness tester. Mechanical property testing: The tensile strength, 100% elongation stress, elongation at break, and tear strength of different rubber compounds are tested using a rubber tensile testing machine. The testing standard is in accordance with GB528-2009. Samples are prepared using a Type I dumbbell-shaped cutter and a right-angle cutter. The cut sample is placed at 25°... o After adjusting the temperature in a C-type forced-air drying oven for 24 hours, the stretching process was performed, with the stretching speed of the stretching machine set to 500 mm / min.

[0038] Table 1: Rubber Formulations and Physicochemical Properties

[0039] Figure 1 The images are optical microscope images of the cross-sections of vulcanized rubber in Comparative Example 3 and Example 2. The magnifications from left to right are 25, 35, and 70, respectively. The fracture surface of Example 2 contains only fine HS particles. Overall, HS is evenly dispersed in SBR. In contrast, the fracture surface of Comparative Example 3 contains large HS particles (white particles), and the interface between HS and SBR is clearly visible.

[0040] Figure 2 The images show cross-sectional views of Comparative Example 1 (a), High-Styrene (b), Comparative Example 3 (gi), and Example 2 (cf) at different magnifications using scanning electron microscopy. In Example 2, 30 parts of high-styrene and 30 parts of SBR were first internally mixed, and then 70 parts of SBR were added for open mixing to prepare a vulcanizate. The cross-section of this vulcanizate was relatively smooth and dense, with only a small number of fine dispersed phase particles. No obvious large agglomerates or interfacial debonding pores were observed, indicating that the pre-internal mixing process can effectively promote the fine dispersion of the high-styrene phase and enhance its interfacial bonding with the SBR matrix. In contrast, the vulcanizate prepared by directly mixing 30 parts of high-styrene and 100 parts of SBR in Comparative Example 3 had a significantly rougher cross-section, with large lamellar structures, tear lines, and localized peeling. This indicates that the high-styrene phase is difficult to fully break down and uniformly disperse during direct mixing, resulting in a large enriched phase region in the system. This leads to poor interfacial compatibility, increased stress concentration, and a greater likelihood of interfacial debonding and phase region pull-out during fracture.

[0041] As shown in Table 1 above, under the same test conditions, the overall performance data of the examples is better than that of the comparative examples. In Example 7, styrene-butadiene rubber and natural rubber were used, and the mixture was coated by internal mixing. Compared with the single styrene-butadiene rubber coating in Example 6, and compared with the ordinary coating in Comparative Example 5, the overall performance data of Example 7 is relatively better.

Claims

1. A high-styrene-reinforced rubber material, comprising a rubber matrix and a reinforcing agent, wherein the reinforcing agent comprises high-styrene, characterized in that, The high-styrene surface is coated with a coating material, which includes styrene-butadiene rubber.

2. The high-styrene-reinforced rubber material according to claim 1, characterized in that, In the reinforcing agent, the weight ratio of the high styrene to the coating material is (10-50):(30-90).

3. The high-styrene-reinforced rubber material according to claim 1 or 2, characterized in that, The coating material is a mixture of styrene-butadiene rubber and natural rubber, and the weight ratio of the styrene-butadiene rubber to the natural rubber is (1-2):(0.5-1).

4. The high-styrene-reinforced rubber material according to claim 1, characterized in that, The rubber matrix includes natural rubber and / or styrene-butadiene rubber.

5. The high-styrene-reinforced rubber material according to claim 1, characterized in that, The weight ratio of the rubber matrix to the reinforcing agent is (100-130):(40-70).

6. A method for preparing a high-styrene-reinforced rubber material as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Place the coating material in a mixer and add high styrene for mixing to obtain core-shell particles coated with high styrene; (2) The rubber matrix is ​​placed in an open mixing mill for plasticizing, and after being wrapped with rollers, the core-shell particles and additives are added and mixed to obtain a high-styrene-reinforced rubber material.

7. The preparation method according to claim 6, characterized in that, In step (1), during internal mixing, the mixing temperature is 110-130℃. First, control the speed to 5-15 rpm and mix for 1-5 minutes. Then, increase the speed to 17-35 rpm and mix for 2-4 minutes.

8. The preparation method according to claim 6, characterized in that, In step (2), the additives include zinc oxide, stearic acid, polyethylene glycol, antioxidant 2246, sun-resistant whitening agent, vulcanization accelerator CZ, vulcanization accelerator DM, and sulfur.

9. The preparation method according to claim 6, characterized in that, In step (2), the rubber matrix is ​​first placed in an open mixing mill for plasticizing, and the temperature is controlled at 30-80℃. It is passed through the mill 1-5 times. After wrapping the rollers, zinc oxide, stearic acid, polyethylene glycol, antioxidant 2246, sun-resistant whitening agent and core-shell particles are added and the rubber is turned 2-5 times. Then, vulcanization accelerator CZ, vulcanization accelerator DM and sulfur are added and the rubber is turned 2-5 times. It is passed through the mill 1-5 times and finally the rubber is discharged and left to stand for 24-36 hours.

Images