A low dynamic ratio, high heat-resistant natural rubber material and its preparation method

Abstract

This invention discloses a low-dynamic-ratio, high-heat-resistant natural rubber material and its preparation method, belonging to the field of rubber component manufacturing technology. It contains the following components by weight: 100 parts natural rubber, 15-20 parts carbon black, 3-5 parts zinc oxide, 1-1.5 parts stearic acid, 1-2 parts first antioxidant, 2-3 parts microcrystalline wax, 0.5-1.5 parts second antioxidant, 1.5 parts third antioxidant, 2-4 parts paraffin oil, 0.4-0.7 parts S-80, 2-3 parts MPTD-70, 0.5-1.5 parts OTOS-80, and 0.5-1.5 parts NS. This invention employs a low-sulfur, high-acceleration vulcanization system, containing more monosulfide bonds and reducing weaker polysulfide bonds. The synergistic effect of the high-speed thiuram-based accelerator MPTD-70 and the sulfenamide-based accelerator OTOS-80 further improves the high-temperature resistance of the rubber backbone.

Description

Technical Field

[0001] This invention belongs to the field of rubber component manufacturing technology, specifically relating to a low dynamic ratio, high heat-resistant natural rubber material and its preparation method. Background Technology

[0002] Natural rubber is widely used in various shock-absorbing products due to its excellent elasticity, superior physical and mechanical properties, and good dynamic fatigue resistance. However, because natural rubber contains double bonds in its olefin chains, it can react with free radicals, oxygen, peroxides, ultraviolet light, and free radical inhibitors. In addition, the presence of electron-donating methyl groups in its structure increases the electron cloud density of the double bonds and enhances the activity of α-H, making natural rubber more prone to aging and resulting in performance degradation. The material is also not resistant to long-term high-temperature environments. Summary of the Invention

[0003] This invention provides a low dynamic ratio, high heat resistance natural rubber material and its preparation method. By adjusting the rubber formulation, the temperature resistance of natural rubber is improved while ensuring a low dynamic ratio.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A low dynamic ratio, high heat-resistant natural rubber material, comprising the following components by weight: 100 parts natural rubber, 15-20 parts carbon black, 3-5 parts zinc oxide, 1-1.5 parts stearic acid, 1-2 parts primary antioxidant, 2-3 parts microcrystalline wax, 0.5-1.5 parts secondary antioxidant, 1.5 parts tertiary antioxidant, 2-4 parts paraffin oil, 0.4-0.7 parts predispersed sulfur S-80, 2-3 parts N,N-dimethyl-N,N-diphenylthiuram disulfide (MPTD-70), 0.5-1.5 parts N-oxodiethylenethiocarbamoyl-N'-oxodiethylenesulfenamide (OTOS-80), and 0.5-1.5 parts N-tert-butyl-2-benzylthiazolylsulfonamide (NS).

[0006] To maintain a low dynamic ratio of natural rubber, this invention does not add heat-resistant styrene-butadiene rubber to the raw rubber formulation system. Instead, it uses Hengmoney 10CV raw rubber. The vulcanization system employs an effective vulcanization system, uses pre-dispersed sulfur S-80, and uses N,N-dimethyl-N,N-diphenylthiuram disulfide (MPTD-70) and N-oxodiethylenethiocarbamoyl-N'-oxodiethylenesulfenamide (OTOS-80) as accelerators to reduce the formation of polysulfide bonds and improve heat resistance.

[0007] The present invention discloses a method for preparing a low dynamic ratio, high heat-resistant natural rubber material, comprising the following steps:

[0008] (1) Preparation of natural rubber: Prepare the materials according to the above formula and send all the raw materials into the internal mixer. After the internal mixing, the hardness, strength and elongation of the rubber are tested. Among them, the rubber with a hardness of 45±5 degrees, strength ≥17MPa and elongation ≥450% is qualified rubber.

[0009] (2) Rubber molding and vulcanization: The qualified rubber is rolled into shape using a two-roll mill at 55-65℃, and then the rolled rubber is placed into a mold in the vulcanization equipment at a pressure of 180-200 kgf / cm². 2 The rubber is vulcanized at a temperature of 160-165℃ for 420-540 seconds.

[0010] (3) Post-processing and inspection: Trim the edges of the vulcanized product and inspect its size and appearance to obtain qualified finished products.

[0011] As a further aspect of the present invention, the carbon black is high-structure general-purpose furnace black N650.

[0012] As a further aspect of the present invention, the first antioxidant is N-isopropyl-N'-phenyl-p-phenylenediamine (4010NA).

[0013] As a further aspect of the present invention, the second antioxidant is DDA-70.

[0014] As a further aspect of the present invention, the third antioxidant is antioxidant RD.

[0015] The beneficial effects of this invention are:

[0016] 1. This invention provides a natural rubber material with low dynamic ratio and high heat resistance, and its preparation method. By adjusting the rubber formulation and changing the vulcanization system, the heat resistance of natural rubber is improved while ensuring low dynamic ratio.

[0017] 2. This invention employs a low-sulfur, high-acceleration vulcanization system, containing more monosulfide bonds and reducing the number of weaker polysulfide bonds. The synergistic effect of the ultra-fast thiuram-based accelerator MPTD-70 and the sulfenamide-based accelerator OTOS-80 further improves the high-temperature resistance of the rubber backbone. Finally, none of the materials used in this invention reduce the performance of natural rubber itself, ultimately resulting in a natural rubber material with a low dynamic ratio and high heat resistance. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1

[0020] A natural rubber material with low dynamic ratio and high heat resistance, comprising the following components by weight:

[0021] 100 parts natural rubber, 17 parts N650 carbon black, 4 parts zinc oxide, 1.5 parts stearic acid, 2 parts N-isopropyl-N'-phenyl-p-phenylenediamine, 3 parts microcrystalline wax, 1.5 parts DDA-70, 1.5 parts antioxidant RD, 3 parts paraffin oil, 0.7 parts predispersed sulfur S-80, 2.1 parts N,N-dimethyl-N,N-diphenylthiuram disulfide, 1.5 parts N-oxodiethylenethiocarbamoyl-N'-oxodiethylenesulfenamide, 0.84 parts N-tert-butyl-2-phenylthiazolylsulfonamide;

[0022] The preparation method of this low dynamic ratio, high heat-resistant natural rubber material includes the following steps:

[0023] (1) Preparation of natural rubber: Weigh the above raw rubber and ingredients, add natural rubber, reinforcing agent, antioxidant, activator, stearic acid and paraffin oil into the internal mixer according to the formula and carry out the first stage of mixing. The vulcanizing agent and accelerator are added in the second stage of mixing to obtain synthetic rubber.

[0024] (2) Rubber molding and vulcanization: The internally mixed rubber is molded using a two-roll mill at 55°C. The molded rubber is then placed into a mold in a vulcanizing device under a pressure of 180 kgf / cm². 2 The rubber was vulcanized at a temperature of 160℃ for 480 seconds.

[0025] (3) Trim the edges of the vulcanized product and inspect its size and appearance to obtain a qualified finished product.

[0026] Example 2

[0027] A natural rubber material with low dynamic ratio and high heat resistance, comprising the following components by weight:

[0028] 100 parts natural rubber, 20 parts N650 carbon black, 4 parts zinc oxide, 1.5 parts stearic acid, 2 parts N-isopropyl-N'-phenyl-p-phenylenediamine, 3 parts microcrystalline wax, 1.5 parts DDA-70, 1.5 parts antioxidant RD, 3 parts paraffin oil, 0.5 parts predispersed sulfur S-80, 2.5 parts N,N-dimethyl-N,N-diphenylthiuram disulfide, 1.5 parts N-oxodiethylenethiocarbamoyl-N'-oxodiethylenesulfenamide, 0.5 parts N-tert-butyl-2-phenylthiazolylsulfonamide;

[0029] The preparation method of this low dynamic ratio, high heat-resistant natural rubber material includes the following steps:

[0030] (1) Preparation of natural rubber: Weigh the above raw rubber and ingredients, add natural rubber, reinforcing agent, antioxidant, activator, stearic acid and paraffin oil into the internal mixer according to the formula and carry out the first stage of mixing. The vulcanizing agent and accelerator are added in the second stage of mixing to obtain synthetic rubber.

[0031] (2) Rubber molding and vulcanization: The internally mixed rubber is molded using a two-roll mill at 60°C. The molded rubber is then placed into a mold in a vulcanizing device under a pressure of 190 kgf / cm². 2 The rubber was vulcanized at a temperature of 160℃ for 420 seconds.

[0032] (3) Trim the edges of the vulcanized product and inspect its size and appearance to obtain a qualified finished product.

[0033] Comparative Example 1

[0034] A natural rubber material with low dynamic ratio and high heat resistance, comprising the following components by weight:

[0035] Natural rubber 80 parts, styrene-butadiene rubber 20 parts, N650 carbon black 17 parts, zinc oxide 4 parts, stearic acid 1.5 parts, N-isopropyl-N'-phenyl-p-phenylenediamine 2 parts, microcrystalline wax 3 parts, DDA-70 1.5 parts, antioxidant RD 1.5 parts, paraffin oil 3 parts, predispersed sulfur S-80 0.7 parts, N,N-dimethyl-N,N-diphenylthiuram disulfide 2.1 parts, N-oxodiethylenethiocarbamoyl-N'-oxodiethylenesulfenamide 1.5 parts, N-tert-butyl-2-phenylthiazolylsulfonamide 0.84 parts;

[0036] The preparation method of this low dynamic ratio, high heat-resistant natural rubber material includes the following steps:

[0037] (1) Preparation of natural rubber: Weigh the above raw rubber and ingredients, add natural rubber, reinforcing agent, antioxidant, activator, stearic acid and paraffin oil into the internal mixer according to the formula and carry out the first stage of mixing. The vulcanizing agent and accelerator are added in the second stage of mixing to obtain synthetic rubber.

[0038] (2) Rubber molding and vulcanization: The rubber after internal mixing is molded by open mill at 60°C, and then the molded rubber is placed in the mold in the vulcanization equipment. The rubber is vulcanized under the conditions of pressure of 190kgf / cm2 and temperature of 160°C for 420s.

[0039] (3) Trim the edges of the vulcanized product and inspect its size and appearance to obtain a qualified finished product.

[0040] Comparative Example 2

[0041] A natural rubber material with low dynamic ratio and high heat resistance, comprising the following components by weight:

[0042] 100 parts natural rubber, 17 parts N650 carbon black, 4 parts zinc oxide, 1.5 parts stearic acid, 2 parts N-isopropyl-N'-phenyl-p-phenylenediamine, 3 parts microcrystalline wax, 1.5 parts DDA-70, 1.5 parts antioxidant RD, 3 parts paraffin oil, 0.7 parts predispersed sulfur S-80, 1.5 parts N-cyclohexyl-2-benzothiazole sulfenamide, 0.5 parts dibenzothiazole disulfide, and 1 part 4,4′-dithiodimorpholine;

[0043] The preparation method of this low dynamic ratio, high heat-resistant natural rubber material includes the following steps:

[0044] (1) Preparation of natural rubber: Weigh the above raw rubber and ingredients, add natural rubber, reinforcing agent, antioxidant, activator, stearic acid and paraffin oil into the internal mixer according to the formula and carry out the first stage of mixing. The vulcanizing agent and accelerator are added in the second stage of mixing to obtain synthetic rubber.

[0045] (2) Rubber molding and vulcanization: The internally mixed rubber is molded using a two-roll mill at 60°C. The molded rubber is then placed into a mold in a vulcanizing device under a pressure of 190 kgf / cm². 2 The rubber was vulcanized at a temperature of 160℃ for 420 seconds.

[0046] (3) Trim the edges of the vulcanized product and inspect its size and appearance to obtain a qualified finished product.

[0047] The natural rubber materials prepared in Examples 1-2 and Comparative Examples 1-2 were tested, and the test standards and results are shown in Table 1.

[0048] Table 1

[0049]

[0050]

[0051] As can be seen from the table, compared with Comparative Examples 1-2, Comparative Example 1 used 80 parts of natural rubber and 20 parts of styrene-butadiene rubber for raw rubber, while keeping the rest the same; Comparative Example 2 used pure natural rubber for raw rubber, and the vulcanization system used a conventional and effective vulcanization system; The natural rubber materials prepared in Examples 1-2 not only have a lower dynamic ratio and high heat resistance, but also have the following characteristics: the present invention uses a low-sulfur, high-accelerator vulcanization system, which contains more monosulfide bonds and reduces the number of polysulfide bonds with relatively weak bond energy. The synergistic effect of the ultra-fast thiuram accelerator MPTD-70 and the sulfenamide accelerator OTOS-80 further improves the high-temperature resistance of the rubber backbone.

[0052] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A natural rubber material with low dynamic ratio and high heat resistance, characterized in that, The product contains the following components by weight: 100 parts natural rubber, 15-20 parts carbon black, 3-5 parts zinc oxide, 1-1.5 parts stearic acid, 1-2 parts primary antioxidant, 2-3 parts microcrystalline wax, 0.5-1.5 parts secondary antioxidant, 1.5 parts tertiary antioxidant, 2-4 parts paraffin oil, 0.4-0.7 parts predispersed sulfur S-80, 2-3 parts N,N-dimethyl-N,N-diphenylthiuram disulfide, 0.5-1.5 parts N-oxodiethylenethiocarbamoyl-N'-oxodiethylenesulfenamide, and 0.5-1.5 parts N-tert-butyl-2-benzylthiazolylsulfonamide.

2. The low dynamic ratio, high heat resistance natural rubber material according to claim 1, characterized in that, The carbon black is a high-structure general-purpose furnace black, N650.

3. The low dynamic ratio, high heat resistance natural rubber material according to claim 1, characterized in that, The first antioxidant is N-isopropyl-N'-phenyl-p-phenylenediamine.

4. The low dynamic ratio, high heat resistance natural rubber material according to claim 1, characterized in that, The second antioxidant is DDA-70.

5. A low dynamic ratio, high heat-resistant natural rubber material according to claim 1, characterized in that, The third antioxidant is antioxidant RD.

6. The method for preparing a low dynamic ratio, high heat-resistant natural rubber material according to claim 1, characterized in that, Includes the following steps: (1) Prepare materials according to the formula and send all raw materials into the internal mixer. After the internal mixer is used to obtain the mixed rubber, test its hardness, strength and elongation. Among them, the rubber with a hardness of 45±5 degrees, strength ≥17MPa and elongation ≥450% is qualified rubber. (2) The qualified rubber is processed by open milling at 55-65℃, and then the processed rubber is placed into a mold in the vulcanizing equipment at a pressure of 180-200 kgf / cm². 2 The rubber is vulcanized at a temperature of 160-165℃ for 420-540 seconds. (3) Trim the edges of the vulcanized product and inspect its size and appearance to obtain a qualified finished product.

Images