BIPB-containing ethylene propylene diene monomer mixed additive and preparation method thereof

Abstract

The invention discloses a BIPB-containing ethylene propylene diene monomer mixed additive and a preparation method thereof. The mixed additive comprises BIPB, ethylene propylene diene monomer, an inorganic inert material, an accelerant and a modified additive, wherein the modified additive is prepared from diphenyl thiourea, styrene, 2-methyl styrene, a scorch retarder, a blooming prevention agent and white carbon black. Compared with the prior art, the mixed additive prepared by the invention has good anti-blooming and anti-scorching effects, and can improve the processing safety and storage stability of rubber products.

Description

Technical Field

[0001] The invention relates to the technical field of rubber additives, and in particular to an ethylene propylene diene monomer rubber mixed additive containing BIPB and a preparation method thereof. Background Art

[0002] In the rubber industry, EPDM rubber, as an important polymer elastomer material, is widely used in automobiles, construction, wires and cables and other fields due to its excellent physical and mechanical properties, aging resistance, weather resistance, heat resistance and electrical insulation properties. However, in practical applications, there are still some performance deficiencies, such as slow vulcanization speed, poor self-adhesion and mutual adhesion, which limit its application under certain specific conditions. In order to overcome these defects, researchers continue to explore new mixing additives and their preparation methods to improve their comprehensive performance.

[0003] BIPB (di-tert-butyl peroxide isopropylbenzene) can be used as a crosslinking agent for chlorinated polyethylene, EPDM rubber, ethylene-vinyl acetate copolymer, silicone rubber, nitrile rubber and other plastics and rubbers in the plastic and rubber industries. It also produces little irritating odor during the operation and in the finished products.

[0004] Rubber additives are usually added to the rubber matrix and play a specific role in the mixing, vulcanization, processing and use of rubber. They can adjust the viscosity, fluidity, crosslinking density, hardness, wear resistance, aging resistance, heat resistance, cold resistance, electrical insulation, flame retardancy and other physical and chemical properties of rubber. The improvement of these properties is directly related to the final quality and application areas of rubber products, such as the production and manufacturing of various rubber products such as tires, seals, hoses, tapes, rubber shoes, rubber gaskets, etc. There are many types of rubber additives, which can be roughly divided into vulcanizers, accelerators, antioxidants, plasticizers, fillers, colorants, foaming agents, flame retardants and other categories. Each additive has its own unique chemical structure and mechanism of action. Through scientific formulation and reasonable addition, the performance of rubber products can be optimized.

[0005] CN110105624A discloses an EPDM rubber crosslinking aid and a sealing strip prepared therefrom. The invention adopts a new type of vulcanization crosslinking aid 1,3-diallylimidazole acrylate, and introduces two structural factors, allyl and acrylate, which inhibit the degradation of the main chain. Both structures contain active hydrogen and have high activity in the presence of peroxide free radicals, and can form CC crosslinking bonds with rubber. At the same time, the presence of anions and cations can also inhibit the consumption of free radicals and keep the vulcanization efficiency unchanged. Although the invention increases the vulcanization speed of EPDM rubber, the rubber prepared by this method is easy to burn and has poor mechanical properties.

[0006] CN118325195A discloses a special anti-scorch agent for chloroprene rubber, a chloroprene rubber compound containing the anti-scorch agent, and a preparation method. In the process of preparing the chloroprene rubber compound, the special anti-scorch agent of the present invention only needs to be added in an amount of 1.5%-2.5% of the mass of chloroprene rubber to extend the scorch time and safe storage period of the chloroprene rubber. Compared with the existing anti-scorch agent, the use of the special anti-scorch agent of the present invention in the preparation of the chloroprene rubber compound can extend the scorch time by about 2 times, and extend the safe storage period of the chloroprene rubber to more than half a year. However, the range of rubbers for which the anti-scorch agent prepared by the invention can be used is limited. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide an EPDM rubber mixing additive containing BIPB to improve the anti-scorch and anti-blooming properties of the rubber.

[0008] To achieve the above-mentioned purpose, the present invention provides an EPDM rubber mixing additive containing BIPB, which comprises the following components, measured by weight: 40-50 parts of BIPB, 40-50 parts of EPDM rubber, 10-20 parts of inorganic inert materials, 1-7 parts of accelerators and 2-8 parts of modified additive additives, wherein the modified additive additive is prepared from diphenylthiourea, styrene, 2-methylstyrene, a scorch retarder, an anti-blooming agent and white carbon black.

[0009] Preferably, the preparation method of the modified additive comprises the following steps:

[0010] Evenly melt diphenylthiourea, styrene and 2-methylstyrene at 85-95°C, then add scorch retarder, anti-floating agent and white carbon black, and mix evenly to obtain the modified additive.

[0011] More preferably, the preparation method of the modified additive comprises the following steps, in parts by weight:

[0012] Evenly melt 2-8 parts of diphenylthiourea, 1-5 parts of styrene and 1-6 parts of 2-methylstyrene at 85-95°C, then add 1-7 parts of anti-scorch agent, 1-7 parts of anti-blooming agent and 5-20 parts of white carbon black, and mix evenly to obtain the modified additive.

[0013] Preferably, the scorch retarder is any one of 1H-isoindole-1,3(2H)-dione-2-[(2-methylcyclohexyl)thio], 2-[(1-chlorocyclohexyl)thio]isoindole-1,3-dione, and N-[(diethoxyphosphinoyl)thio]-N-ethylethylamine.

[0014] More preferably, the scorch retarder is N-[(diethoxyphosphonyl)thio]-N-ethylethylamine.

[0015] Preferably, the accelerator is any one of 4-fluoro-2(3H)-benzothiazolethione, 6-amino-2-mercaptobenzothiazole, and 2-mercapto-6-methoxybenzothiazole.

[0016] Preferably, the inorganic inert material is a mixture of silicon dioxide, zinc oxide and titanium dioxide.

[0017] A method for preparing an EPDM rubber mixing additive containing BIPB comprises the following steps, measured in parts by weight:

[0018] 40-50 parts of BIPB, 40-50 parts of EPDM rubber and 10-20 parts of inorganic inert materials are mixed, and then 1-7 parts of accelerator, 1-10 parts of vulcanizer and 2-8 parts of modified additive are added and mixed, and the BIPB-containing EPDM rubber mixed additive is prepared after internal mixing and extrusion.

[0019] Preferably, the mixing temperature is controlled at 80-122°C.

[0020] Preferably, the mixing time is controlled at 60-80 min.

[0021] In this recipe, the ingredients and their functions are as follows:

[0022] BIPB: As a key component in the peroxide vulcanization system, BIPB decomposes at high temperature to produce free radicals, which in turn trigger a cross-linking reaction between EPDM rubber molecular chains, transforming the rubber from a linear structure to a three-dimensional network structure, thereby realizing the vulcanization process of the rubber. The BIPB in the present invention uses BIPB produced by Guangxi Donglan New Materials Co., Ltd., with a trade name of B13, which is 1,3-di-tert-butyl peroxide isopropylbenzene with a pure meta structure.

[0023] EPDM rubber: Adding a certain proportion of rubber to the additive can improve the affinity between the additive and the rubber, making the additive easier to disperse in the rubber, thereby achieving better fusion.

[0024] Inorganic inert materials: Inorganic inert materials mainly play the role of filling, reinforcing and adjusting performance.

[0025] Accelerator: Accelerator mainly accelerates the vulcanization reaction, shortens the vulcanization time and improves the vulcanization effect. Vulcanization is a key step in rubber processing, which forms a cross-linked structure between rubber molecular chains, thereby improving the physical and mechanical properties of rubber.

[0026] Anti-scorch agent: The main function of the anti-scorch agent is to delay or inhibit the early scorching of rubber during the processing, that is, to prevent the rubber from cross-linking before the predetermined vulcanization conditions are reached, thereby ensuring the stability and controllability of the rubber mixing additives during the processing.

[0027] Anti-floating agent: Anti-floating agent can effectively prevent the frosting phenomenon caused by the precipitation of additives during the processing, storage and use of rubber products. By improving the solubility and stability of rubber in compounding agents, anti-floating agent ensures the uniform dispersion and long-lasting effect of additives in the rubber matrix, thereby avoiding the formation of visible precipitates of additives on the surface or inside of the rubber. It can be used in conjunction with anti-scorch agents to achieve better anti-floating performance.

[0028] Beneficial effects of the present invention:

[0029] Compared with the prior art, a scorch preventer is prepared by reacting diphenylthiourea, styrene and 2-methylstyrene, which is then mixed with another scorch preventer and white carbon black to obtain a modified additive. The modified additive is mixed with BIPB, EPDM rubber and an inorganic inert material and then applied to subsequent rubber processing to achieve a good scorch preventer effect. DETAILED DESCRIPTION

[0030] Parameters for specific chemical substances used, sources.

[0031] 1H-Isoindole-1,3(2H)-dione-2-[(2-methylcyclohexyl)thio], CAS No.: 88683-40-3.

[0032] 2-[(1-chlorocyclohexyl)thio]isoindole-1,3-dione, CAS No.: 17796-86-0.

[0033] Ethanamine, N-[(diethoxyphosphinyl)thio]-N-ethyl-, CAS No.: 5626-97-1.

[0034] 4-Fluoro-2(3H)-benzothiazolethione, CAS number: 154327-24-9.

[0035] 6-Amino-2-mercaptobenzothiazole, CAS number: 7442-07-1.

[0036] 2-Mercapto-6-methoxybenzothiazole, CAS number: 2182-73-2.

[0037] SEBS defrost, model: FPS-10, Zhengzhou Huilin.

[0038] EPDM rubber: Brand: 4770P, DowDuPont.

[0039] White carbon black: 325 mesh.

[0040] Example 1

[0041] A method for preparing an EPDM rubber mixing additive containing BIPB comprises the following steps:

[0042] Step 1: Mix 40kg BIPB, 50kg EPDM rubber, 5kg silica, 5kg zinc oxide and 5kg titanium dioxide at 100°C for 30min, then add 5kg 6-amino-2-mercaptobenzothiazole and 5kg modified additive and mix at 110°C for 40min, mix at 50°C and 50rpm for 10min, and extrude to prepare BIPB-containing EPDM rubber mixed additive.

[0043] The preparation method of the modified additive comprises the following steps:

[0044] 3 kg of diphenylthiourea, 3 kg of styrene and 3 kg of 2-methylstyrene were melted evenly at 90°C, and then 5 kg of N-[(diethoxyphosphonyl)thio]-N-ethylethylamine, 5 kg of SEBS defrost agent and 20 kg of white carbon black were added and mixed evenly to obtain the modified additive.

[0045] Diphenylthiourea: It has certain reactivity and can react with other components such as styrene, 2-methylstyrene, etc. at high temperature to prepare anti-scorch agent, thereby extending the anti-scorch time of rubber. At the same time, the generated product can further assist the additionally added anti-scorch agent, thereby helping to form a stable modified additive system, which is beneficial to improve the modified additive after mixing with EPDM rubber to achieve better anti-scorch effect.

[0046] Styrene: It has certain reactivity and can react with other ingredients such as diphenylthiourea and 2-methylstyrene at high temperature to prepare anti-scorching agents, which can improve the stability and anti-scorching performance of additives.

[0047] 2-Methylstyrene: It mainly plays the role of adjusting the physical and chemical properties of the modified additive, promoting compatibility with other components, and possibly participating in the formation of complex cross-linked structures. Similar to styrene, 2-methylstyrene can react to increase the anti-scorch effect of the modified additive.

[0048] Example 2

[0049] The difference between Example 2 of the present application and Example 1 is that the N-[(diethoxyphosphinoyl)thio]-N-ethylethylamine in Example 1 is replaced by 1H-isoindole-1,3(2H)-dione-2-[(2-methylcyclohexyl)thio].

[0050] Example 3

[0051] The difference between Example 3 of the present application and Example 1 is that the N-[(diethoxyphosphinoyl)thio]-N-ethylethylamine in Example 1 is replaced by 2-[(1-chlorocyclohexyl)thio]isoindole-1,3-dione.

[0052] Example 4

[0053] The difference between Example 4 of the present application and Example 1 is that the 6-amino-2-mercaptobenzothiazole in Example 1 is replaced by 2-mercapto-6-methoxybenzothiazole.

[0054] Example 5

[0055] The difference between Example 5 of the present application and Example 1 is that the 6-amino-2-mercaptobenzothiazole in Example 1 is replaced by 4-fluoro-2(3H)-benzothiazolethione.

[0056] Comparative Example 1

[0057] The difference between Comparative Example 1 of the present application and Example 1 is that the N-[(diethoxyphosphonyl)thio]-N-ethylethylamine in Example 1 is replaced by N-cyclohexylthiophthalimide.

[0058] Comparative Example 2

[0059] The difference between Comparative Example 2 of the present application and Example 1 is that no white carbon black is added in Comparative Example 2.

[0060] Test Example 1

[0061] Vulcanization characteristics: Use MDR2000 rotorless vulcanizer according to the test method in GB / T16584-1996 "Determination of vulcanization characteristics of rubber with rotorless vulcanizer": 15kg of EPDM rubber mixed additive containing BIPB, 100kg of EPDM rubber raw rubber, 2kg of stearic acid, and 45kg of paraffin oil prepared in the above Examples 1-5 and Comparative Examples 1-2 are mixed in a 50°C, 60rpm internal mixer, and the rubber discharge time is 7min for a period of mixing. After the mixed rubber is rolled, 1kg of sulfur is added. After the material is eaten, mix for 8min, thin pass 10 times, exhaust, and sheet to obtain a mixed rubber. The obtained mixed rubber is tested, the vulcanization temperature is 120°C, the sample mass is about 5g, and the shape is disc-shaped. The test results are shown in Table 1:

[0062] Table 1: Scorch time

[0063] Experimental groups Scorch time (min) Example 1 83 Example 2 72 Example 3 71 Example 4 74 Example 5 68 Comparative Example 1 51 Comparative Example 2 44

[0064] Test Example 2

[0065] 15 kg of EPDM rubber mixing aid containing BIPB prepared in Examples 1-5 and Comparative Examples 1-2, 100 kg of EPDM rubber raw rubber, 2 kg of stearic acid, and 45 kg of paraffin oil were mixed in an internal mixer at 50°C and 60 rpm, and the rubber discharge time was 7 min for a period of mixing. After the mixed rubber material was rolled, 1 kg of sulfur was added. After the material was fed, the rubber was mixed for 8 min, thinned 10 times, exhausted, and sheeted to obtain a mixed rubber; the mixed rubber was vulcanized at 170°C for 6 min to obtain rubber.

[0066] Anti-blooming performance: The rubber prepared above was immersed in a 1wt% saline solution for 2 hours, taken out and rinsed with tap water, and after standing for 24 hours, the sample was placed in a 70℃ high temperature environment for 2 hours, and then placed in a -20℃ low temperature environment for 2 hours. The sample was taken out to observe the surface frost situation, and the frost situation was recorded from high to low in order of severe frost, slight frost, and no frost according to the size of the frost area. The test results are shown in Table 2:

[0067] Table 2 Anti-floating performance

[0068]

[0069]

[0070] Through the test data results in Table 1 and Table 2 of Examples 1-5 and Comparative Example 1, it can be found that the anti-blooming effect and anti-scorch effect of the EPDM rubber containing BIPB prepared in Example 1 are the best.

[0071] Comparing the tabular data in Examples 1-3 and Comparative Example 1, it is found that the anti-scorch time and anti-blooming performance of the EPDM rubber containing BIPB in Example 1 are different. The possible reason is that different anti-scorch agents are used. The anti-scorch agent can react chemically with the accelerator, and this reaction prevents the promoting effect of the accelerator. When the anti-scorch agent is completely consumed, the amount of the accelerator gradually increases, and the new polymer generated by the previous reaction also releases the accelerator. Therefore, the main effect of adding the anti-scorch agent is that the anti-scorch agent has reacted with the accelerator before the vulcanization product reacts in large quantities, so the anti-scorch agent delays the generation of polysulfide radicals in the cross-linked rubber, achieving the effect of delayed vulcanization. In addition to containing a group that reacts with the accelerator, N-[(diethoxyphosphonyl)thio]-N-ethylethylamine in Example 1 also contains a phosphorus atom. The organophosphorus compound in Example 1 can significantly prolong the scorch time, and has almost no effect on the vulcanization speed of the rubber, and has no significant effect on the crosslinking density of the vulcanized rubber. At the same time, it can also improve the adhesion between the rubber and the skeleton material. The scorch retarder and the blooming agent work synergistically, so that the prepared rubber has the characteristic of not blooming, and can improve the stability of insoluble sulfur in the rubber material. The scorch retarder in Examples 2-3 and Comparative Example 1 is only a sulfonamide scorch retarder, and its anti-scorch and anti-blooming performance is worse than that of the organophosphorus scorch retarder.

[0072] Comparing the tabular data in Example 1 and Examples 4-5, it is found that the anti-scorch time and anti-blooming performance of the EPDM rubber containing BIPB in Example 1 are different. The possible reason is that different accelerators are used. Sulfonamide accelerators are a type of accelerator with relatively excellent performance in various aspects. They have a long scorch time and can be quickly vulcanized. At the same time, they can ensure a flat vulcanization curve and have good processing safety. Because of the enhanced interaction between silica and the accelerator, a more stable network structure is formed in the rubber, which may slow down the speed of the cross-linking reaction during the vulcanization process. At the same time, due to the interaction between silica and the accelerator, silica has better dispersibility, and a more uniform dispersion means that the spacing between silica particles is more consistent, thereby reducing the possibility of excessive local cross-linking density. This uniform cross-linked network structure helps to extend the pre-vulcanization time, thereby improving the anti-scorch performance of the rubber.

[0073] Compared with Example 1 and Comparative Example 2, when the rubber scorch time in Example 1 is prolonged, the white carbon black has a longer time to move, aggregate and interact with the accelerator, the number and size of the white carbon black group increases, and more stress concentration points are formed. The stress concentration effect causes the tensile strength and tear strength of the rubber to decrease. In Comparative Example 2, because white carbon black is not used, the accelerator cannot interact with white carbon black, so the anti-scorch effect of the rubber is poor. In addition, the inorganic filler has an adsorption effect on the accelerator, which will produce a delay effect during the vulcanization process of the rubber.

Claims

1. An EPDM rubber mixing additive containing BIPB, characterized in that: The invention comprises the following components by weight: 40-50 parts of BIPB, 40-50 parts of EPDM rubber, 10-20 parts of inorganic inert materials, 1-7 parts of accelerators and 2-8 parts of modified additives, wherein the modified additives are prepared from diphenylthiourea, styrene, 2-methylstyrene, a scorch retarder, a bloom preventer and white carbon black.

2. The BIPB-containing EPDM rubber mixing aid according to claim 1, characterized in that: The preparation method of the modified additive comprises the following steps: evenly melting diphenylthiourea, styrene and 2-methylstyrene at 85-95°C, adding a scorch retarder, an anti-blooming agent and white carbon black, and mixing evenly to obtain the modified additive.

3. The BIPB-containing EPDM rubber mixing aid according to claim 2, characterized in that: The preparation method of the modified additive comprises the following steps, calculated by weight: Evenly melt 2-8 parts of diphenylthiourea, 1-5 parts of styrene and 1-6 parts of 2-methylstyrene at 85-95°C, then add 1-7 parts of anti-scorch agent, 1-7 parts of anti-blooming agent and 5-20 parts of white carbon black, and mix evenly to obtain the modified additive.

4. The BIPB-containing EPDM rubber mixing aid according to claim 1, characterized in that: The anti-scorching agent is any one of 1H-isoindole-1,3(2H)-dione-2-[(2-methylcyclohexyl)thio], 2-[(1-chlorocyclohexyl)thio]isoindole-1,3-dione, and N-[(diethoxyphosphonyl)thio]-N-ethylethylamine.

5. The BIPB-containing EPDM rubber mixing aid according to claim 4, characterized in that: The scorch retarder is N-[(diethoxyphosphonyl)thio]-N-ethylethylamine.

6. The BIPB-containing EPDM rubber mixing aid according to claim 1, characterized in that: The accelerator is any one of 4-fluoro-2(3H)-benzothiazolethione, 6-amino-2-mercaptobenzothiazole, and 2-mercapto-6-methoxybenzothiazole.

7. The BIPB-containing EPDM rubber mixing aid according to claim 1, characterized in that: The inorganic inert material is a mixture of silicon dioxide, zinc oxide and titanium dioxide.

8. A method for preparing an EPDM rubber mixing additive containing BIPB as claimed in any one of claims 1 to 7, characterized in that: The method comprises the following steps, in parts by weight: 40-50 parts of BIPB, 40-50 parts of EPDM rubber and 10-20 parts of inorganic inert materials are mixed, and then 1-7 parts of accelerator and 2-8 parts of modified additive are added and mixed, and the BIPB-containing EPDM rubber mixed additive is prepared after internal mixing and extrusion.

9. The method for preparing the BIPB-containing EPDM rubber mixing aid according to claim 8, characterized in that: The mixing temperature is controlled at 80-122°C.

10. The method for preparing the BIPB-containing EPDM rubber mixing aid according to claim 8, characterized in that: The mixing time is controlled at 60-80 minutes.

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