Vulcanization method and application of modified polyisoprene rubber

Abstract

The invention provides a vulcanization method and application of modified polyisoprene rubber, and belongs to the technical field of chemical materials, and the vulcanization method comprises the following steps: step 1, dissolving polyisoprene rubber into a rubber solution with the concentration of 1-10%, adding a polar monomer or a novel organic compound modifier into the rubber solution, then adding an initiator, and reacting at 60-80 DEG C for 8-12 hours to obtain modified polyisoprene rubber; and separating out the reaction polymerization liquid by using an organic solvent to obtain the modified polyisoprene rubber. Step 2, emulsifying the modified polyisoprene rubber into an emulsion, adding sulfur, a polyfunctional group cross-linking agent and an auxiliary agent, pre-vulcanizing at 20-30 DEG C for 12-17 hours, and vulcanizing at 90-120 DEG C for 30-50 minutes. By optimizing the cross-linking reaction path, the invention provides a vulcanization process which is more environment-friendly, efficient and safe, can greatly reduce the consumption of sulfur and shorten the vulcanization time, is suitable for preparing polyisoprene rubber products with excellent physical properties, and has important industrial application value and wide market prospects.

Description

Technical Field

[0001] The invention relates to the technical field of chemical materials, and in particular to a vulcanization method and application of modified polyisoprene rubber. Background Art

[0002] Polyisoprene rubber is a general-purpose rubber material made from the polymerization of isoprene monomers. Isoprene rubber with a high cis structure is highly similar to the molecular structure of natural rubber and does not contain protein. It is a general-purpose synthetic rubber with excellent comprehensive properties. Today, isoprene rubber has been widely used in automobile tires, film products, wires and cables, conveyor belts, and hoses.

[0003] At present, the modification of polyisoprene rubber includes physical blending modification and chemical modification. The chemical modification mainly includes epoxidation modification, hydroxylation modification, grafting modification and hydrogenation addition modification. Among them, grafting modification is a more commonly used modification method. Solution grafting method and emulsion grafting method can be used, and the grafting monomer can also be copolymerized with isoprene for grafting. The solution grafting method is simple and easy to operate, and there are many types of grafting monomers to choose from.

[0004] In terms of vulcanization process, the current vulcanization of polyisoprene rubber usually adopts traditional vulcanization packages, which contain ingredients such as sulfur, accelerators, activators and scorch retardants. Among them, accelerators are an indispensable component. Common organic accelerators such as thiazoles, thiurams, subsulfuramides and dithiocarbamates can effectively accelerate the rate of vulcanization reaction, but they are often toxic and may decompose to produce carcinogens such as nitrosamines during high-temperature vulcanization. In addition, if the vulcanization process is incomplete, it will not only lead to a decline in the performance of rubber products, but also produce a pungent odor and may cause damage to human health. Therefore, it is necessary to develop a new type of polyisoprene rubber with a new structure and optimize the vulcanization process to prepare safe, non-toxic and non-allergenic rubber products. Summary of the invention

[0005] The purpose of the present invention is to provide a vulcanization method and application of modified polyisoprene rubber to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A vulcanization method for modified polyisoprene rubber comprises the following steps:

[0008] Step 1, dissolving polyisoprene rubber into a 1-10% concentration of glue solution, adding a polar monomer or a novel organic compound modifier to the glue solution, and then adding an initiator, reacting at 60-80° C. for 8-12 hours to obtain a reaction polymer solution, and then precipitating with an organic solvent to obtain a modified polyisoprene rubber;

[0009] Step 2: emulsify the modified polyisoprene rubber into an emulsion, add a multifunctional crosslinking agent, sulfur and additives, pre-vulcanize at 20-30° C. for 12-17 hours, and then vulcanize at 90-120° C. for 30-50 minutes.

[0010] Preferably, in step 1, by weight, the polyisoprene rubber is 100 parts, the polar monomer is 30-50 parts, and the initiator is 1-2 parts.

[0011] Preferably, in step 1, the glue solvent includes one or more of cyclohexane, n-hexane, toluene and xylene.

[0012] Preferably, in step 1, the organic solvent used for precipitation includes one or more of ethanol, methanol, acetone and petroleum ether.

[0013] Preferably, in step 1, 30-50 parts of a novel organic compound modifier: a siloxy-containing acrylic ester compound or 2-(vinyl ether)-3-methylimidazole or bis(allyl)phenylphosphine oxide are added.

[0014] Preferably, in step 2, by weight, the multifunctional cross-linking agent is 1-2 parts, sulfur is 0.3-0.5 parts, and the auxiliary agent is 1-3 parts.

[0015] Preferably, the polar monomer includes one or more of acrylate and its derivatives, acrylic acid and its derivatives, phospholipids and its derivatives, mercapto acids and their derivatives, and mercaptoamine and its derivatives.

[0016] Preferably, the initiator includes one or more of azobisisobutyl cyanide, azobisisoheptanenitrile, dicumyl peroxide, benzoyl peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl hydroperoxide, potassium persulfate, sodium persulfate, and ammonium persulfate.

[0017] Preferably, in step 2, the multifunctional cross-linking agent includes one or more of a polyacid, a polyol, a polyamine, and a polyepoxide.

[0018] Preferably, in step 2, the auxiliary agent is a mixture of zinc oxide, potassium hydroxide, titanium dioxide and antioxidant 264.

[0019] The invention also provides an application of a vulcanization method of modified polyisoprene rubber in modified polyisoprene rubber.

[0020] The beneficial effects of the above technical solution of the present invention are as follows:

[0021] The present invention introduces polar functional groups into the rubber chain by adding polar monomers into the polyisoprene rubber glue for graft copolymerization, and adopts multifunctional compounds that can react with the polar functional groups to form covalent bonds to form crosslinking pairs. The covalent bond crosslinking between the crosslinking pairs and the sulfur crosslinking play a synergistic role, thereby achieving complete replacement of traditional accelerators.

[0022] The present invention optimizes the cross-linking reaction path, provides a more environmentally friendly, efficient and safe vulcanization process, can greatly reduce the amount of sulfur used and shorten the vulcanization time, is suitable for preparing polyisoprene rubber products with excellent physical properties, and has important industrial application value and broad market prospects. DETAILED DESCRIPTION

[0023] In order to make the present application easier to understand, the present application will be further described in detail below in conjunction with the examples, which are merely illustrative and are not intended to limit the scope of application of the present application. The raw materials or components used in the present application can be obtained through commercial routes or conventional methods unless otherwise specified.

[0024] Example 1

[0025] The vulcanization method of the modified polyisoprene rubber in the above embodiment comprises the following steps:

[0026] Step 1: Dissolve 100 parts of polyisoprene rubber in toluene to prepare a 5% concentration of rubber solution, add 20 parts of butyl acrylate, 10 parts of methacrylic acid and 1 part of azobisisobutyronitrile, and stir and react at 60°C for 12 hours. After the reaction is completed, pour the polymer solution into ethanol for precipitation to obtain modified polyisoprene rubber, wash it with ethanol three times, and then dry it in an oven at 60°C to constant weight.

[0027] Step 2: emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 1 part of bio-based epoxidized soybean oil, 0.3 parts of sulfur and 2 parts of additives based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 30°C for 14 hours, pour into a film mold, and then vulcanize at 110°C for 40 minutes to prepare a film product.

[0028] The mechanical tensile properties of the film were tested after demoulding.

[0029] Example 2

[0030] The vulcanization method of the modified polyisoprene rubber in the above embodiment comprises the following steps:

[0031] Step 1: Dissolve 100 parts of polyisoprene rubber in toluene to prepare a 10% concentration of rubber solution, add 30 parts of octyl acrylate, 20 parts of mercaptoethylamine and 2 parts of cumene peroxide, and stir and react at 70°C for 10 hours. After the reaction is completed, pour the polymer solution into acetone to precipitate to obtain modified polyisoprene rubber, wash it with acetone three times, and then dry it in a 60°C oven to constant weight.

[0032] Step 2: emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 1.5 parts of epoxidized linseed oil, 0.4 parts of sulfur and 3 parts of additives based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 20° C. for 12 hours, pour into a film mold, and then vulcanize at 90° C. for 50 minutes to prepare a film product.

[0033] The mechanical tensile properties of the film were tested after demoulding.

[0034] Example 3

[0035] The vulcanization method of the modified polyisoprene rubber in the above embodiment comprises the following steps:

[0036] Step 1: Dissolve 100 parts of polyisoprene rubber in toluene to prepare a 6% concentration of rubber solution, add 40 parts of phosphatidyl alcohol and 1.5 parts of benzoyl peroxide, and stir and react at 80°C for 8 hours. After the reaction is completed, pour the polymer solution into petroleum ether for precipitation to obtain modified polyisoprene rubber, wash it with petroleum ether three times, and then dry it in a 60°C oven to constant weight.

[0037] Step 2: emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 2 parts of hexamethylenetetramine, 0.5 parts of sulfur and 2 parts of additives based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 25° C. for 17 hours, pour into a film mold, and then vulcanize at 120° C. for 30 minutes to prepare a film product.

[0038] The mechanical tensile properties of the film were tested after demoulding.

[0039] Example 4

[0040] The vulcanization method of the modified polyisoprene rubber in the above embodiment comprises the following steps:

[0041] Step 1: Dissolve 100 parts of polyisoprene rubber in toluene to prepare a 1% rubber solution, add 20 parts of thioglycolic acid, 15 parts of phosphatidylethanolamine and 1.5 parts of azobisisoheptanenitrile, and stir at 70°C for 11 hours. After the reaction, pour the polymer solution into ethanol for precipitation to obtain modified polyisoprene rubber, wash it with ethanol three times, and then dry it in an oven at 60°C to constant weight.

[0042] Step 2: emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 1.5 parts of phosphatidylinositol, 0.4 parts of sulfur and 1 part of an additive based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 30° C. for 15 hours, pour into a film mold, and then vulcanize at 110° C. for 40 minutes to prepare a film product.

[0043] The mechanical tensile properties of the film were tested after demoulding.

[0044] Comparative Example 1

[0045] The difference between it and Example 1 is that:

[0046] 100 parts of unmodified polyisoprene rubber were emulsified into an emulsion by a conventional emulsification method, and 1.5 parts of sulfur, 2 parts of CBS (N-cyclohexyl-2-benzothiazolesulfonamide) accelerator and 2 parts of auxiliary agents were added. After pre-vulcanization at 30°C for 24 hours, the mixture was poured into a film mold and then vulcanized at 120°C for 30 minutes to prepare a film product.

[0047] The mechanical tensile properties of the film were tested after demoulding.

[0048] Comparative Example 2

[0049] The difference between it and Example 1 is that:

[0050] Step 1: Dissolve 100 parts of polyisoprene rubber in toluene to prepare a 4% concentration of rubber solution, add 30 parts of octyl acrylate, 20 parts of mercaptoethylamine and 1 part of cumene peroxide, and stir and react at 60°C for 12 hours. After the reaction is completed, pour the polymer solution into ethanol for precipitation to obtain modified polyisoprene rubber, wash it with ethanol three times, and then dry it in an oven at 60°C to constant weight.

[0051] Step 2: emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 2 parts of sulfur, 1.8 parts of TBBS (N-tert-butyl-2-benzothiazolesulfonamide) accelerator and 2 parts of auxiliary agent based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 30° C. for 20 hours, pour into a film mold, and then vulcanize at 90° C. for 60 minutes to prepare a film product.

[0052] The mechanical tensile properties of the film were tested after demoulding.

[0053] Comparative Example 3

[0054] Step 1: Dissolve 100 parts of polyisoprene rubber in toluene to prepare a 5% concentration of rubber solution, add 20 parts of butyl acrylate, 10 parts of methacrylic acid and 1 part of azobisisobutyronitrile, and stir and react at 70°C for 11 hours. After the reaction is completed, pour the polymer solution into acetone to precipitate to obtain modified polyisoprene rubber, wash it with acetone three times, and then dry it in an oven at 60°C to constant weight.

[0055] Step 2: emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 1.7 parts of sulfur, 2 parts of DM (dibenzothiazole disulfide) accelerator, and 3 parts of auxiliary agent based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 30° C. for 24 hours, pour into a film mold, and then vulcanize at 120° C. for 30 minutes to prepare a film product.

[0056] The mechanical tensile properties of the film were tested after demoulding.

[0057] The test results of the mechanical tensile properties of the films of Examples 1-4 and Comparative Examples 1-3 are shown in the following table:

[0058] Tensile strength / MPa Elongation at break / % Modulus (500%) / MPa Example 1 23 850％ 3.1 Example 2 22 880％ 2.8 Example 3 24 800％ 3.2 Example 4 23 820％ 2.5 Comparative Example 1 20 750％ 3.5 Comparative Example 2 19 700％ 4.0 Comparative Example 3 18 720％ 3.8

[0059] From the above test results, it can be seen that the present invention adopts the synergistic mechanism of covalent bond crosslinking and sulfur crosslinking between crosslinking pairs in the vulcanization process to replace the use of traditional accelerators, effectively avoiding product quality problems and potential health risks caused by incomplete vulcanization, significantly improving the mechanical tensile properties of the final product, and greatly reducing the amount of sulfur used and shortening the vulcanization time.

[0060] By optimizing the cross-linking reaction path, the present invention ensures the thoroughness and controllability of the vulcanization process and eliminates the potential threat of unreacted chemicals to human health. Data show that the modified polyisoprene rubber treated by the method of the present invention has excellent results in key mechanical performance indicators such as modulus, tensile strength and elongation at break at 500% strain.

[0061] Example 5

[0062] The purpose is to provide a new modified polyisoprene rubber vulcanization method and application to solve the deficiencies in the prior art.

[0063] The novel organic compound modifier used in the present invention is a silicon-oxygen-containing acrylic ester compound, and its general structural formula is: CH=CH-COO-(CH)-Si(OR) (wherein n is an integer of 2-6, and R is methyl or ethyl).

[0064] Design principles and group action mechanisms

[0065] Containing siloxane groups: Silicon atoms have empty orbitals, which can form coordination bonds with active sites on rubber molecular chains, enhancing the interaction between rubber molecular chains. At the same time, siloxane groups can undergo hydrolysis and condensation reactions at high temperatures to form a siloxane network structure, further improving the crosslinking density and heat resistance of rubber.

[0066] Acrylate group: Acrylate group (CH=CH-COO-) can be grafted and copolymerized with the double bonds on the polyisoprene rubber molecular chain through free radical polymerization. Under the action of the initiator, the double bonds of the acrylate group are opened and connected with the rubber molecular chain, thereby introducing the siloxy-containing group into the rubber molecular chain. This graft copolymerization reaction can improve the polarity and compatibility of the rubber, allowing the rubber to better cooperate with other additives in the subsequent vulcanization process.

[0067] Vulcanization method

[0068] A vulcanization method for modified polyisoprene rubber comprises the following steps:

[0069] Step 1, dissolving polyisoprene rubber into a glue solution with a concentration of 2-8%, adding the above-mentioned new organic compound modifier and initiator to the glue solution, reacting at 50-70°C for 10-15h to obtain a reaction polymer solution, and then precipitating with an organic solvent to obtain a modified polyisoprene rubber. Among them, by weight, 100 parts of polyisoprene rubber, 20-40 parts of new organic compound modifier, and 0.5-1.5 parts of initiator. The glue solution solvent can be selected from one or more of cyclohexane, n-heptane, benzene, etc. The organic solvent for precipitation can be selected from one or more of isopropanol, butanone, ether, etc. The initiator can be selected from one or more of azobisisobutyronitrile, benzoyl peroxide, ammonium persulfate, etc.

[0070] Step 2: emulsify the modified polyisoprene rubber into an emulsion, add a multifunctional crosslinking agent, sulfur and an auxiliary agent, pre-vulcanize at 15-25°C for 10-15h, and then vulcanize at 80-110°C for 20-40min. In parts by weight, the multifunctional crosslinking agent is 0.5-1.5 parts, the sulfur is 0.2-0.4 parts, and the auxiliary agent is 0.5-2 parts. The multifunctional crosslinking agent can be selected from one or more of polyols, polyamines, etc. The auxiliary agent is a mixture of zinc oxide, stearic acid, and antioxidant RD.

[0071] The specific steps include:

[0072] Step 1: dissolve 100 parts of polyisoprene rubber in n-heptane to prepare a 5% glue solution, add 30 parts of a new organic compound modifier (such as CH=CH-COO-(CH)-Si(OCH)) and 1 part of azobisisobutyronitrile to the glue solution, react at 60°C for 12 hours, and obtain a polymer solution after the reaction is completed. Then, pour the polymer solution into isopropanol for precipitation to obtain a modified polyisoprene rubber, wash it three times with isopropanol, and then dry it in a 55°C oven to constant weight.

[0073] Step 2: emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 1 part of trimethylolpropane, 0.3 parts of sulfur, and 1.5 parts of additives based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 20°C for 12 hours, pour into a film mold, and then vulcanize at 90°C for 30 minutes to prepare a film product.

[0074] Comparative Example

[0075] The film product was prepared by adopting the conventional unmodified polyisoprene rubber vulcanization method, that is, without adding the novel organic compound modifier, and the other vulcanization conditions were the same as those in the embodiment.

[0076] Performance Testing

[0077] The film products prepared in the examples and comparative examples were subjected to mechanical property tests, including tensile strength, elongation at break, modulus and other index tests. The test results showed that the film products prepared in the examples were superior to the comparative examples in terms of tensile strength and elongation at break, and had a moderate modulus, indicating that the modified vulcanization method of the present invention can effectively improve the performance of polyisoprene rubber products.

[0078] Example 6

[0079] A new type of organic compound modifier is used.

[0080] The novel organic compound modifier used in the present invention is 2-(vinyl ether)-3-methylimidazole, and the imidazole ring structure is as follows: the imidazole ring has electron-rich characteristics, and the nitrogen atoms on the ring can attract each other with the unsaturated bonds in the polyisoprene rubber molecular chain through π-stacking, so that the modifier molecules can be well attached to the rubber molecular chain. During the vulcanization process, the nitrogen atoms can also react with sulfur as active sites to form a sulfur-nitrogen bond cross-linking structure, thereby enhancing the stability and heat resistance of the rubber network. At the same time, the presence of the imidazole ring can improve the rigidity of the rubber molecular chain, which helps to improve the modulus of the rubber product.

[0081] Vinyl ether group: Vinyl ether (-CH=CH-O-) group has high reactivity and can undergo free radical polymerization under the action of initiator. It can undergo addition reaction with double bonds on the polyisoprene rubber molecular chain to introduce imidazole ring structure into the rubber molecular chain. This graft copolymerization reaction can not only improve the polarity of rubber and compatibility with other additives, but also provide more active sites for subsequent vulcanization crosslinking, making the vulcanization reaction more uniform and efficient, thereby improving vulcanization efficiency and reducing sulfur usage.

[0082] A vulcanization method for modified polyisoprene rubber comprises the following steps:

[0083] Step 1: dissolve the polyisoprene rubber into a glue solution with a concentration of 3-9%, add the above-mentioned new organic compound modifier and initiator to the glue solution, react at 55-75°C for 9-13h to obtain a reaction polymer solution, and then precipitate with an organic solvent to obtain a modified polyisoprene rubber. Among them, by weight, 100 parts of polyisoprene rubber, 25-45 parts of new organic compound modifier, and 0.8-1.8 parts of initiator. The glue solution solvent can be selected from one or more aromatic hydrocarbon solvents such as benzene, toluene, and xylene. The organic solvent for precipitation can be selected from one or more alcohol solvents such as methanol, ethanol, and isopropanol. The initiator can be selected from one or more azobisisoheptanitrile, dibenzoyl peroxide, potassium persulfate, etc.

[0084] Step 2: Emulsify the modified polyisoprene rubber into an emulsion, add a multifunctional crosslinking agent, sulfur and an auxiliary agent, pre-vulcanize at 18-28°C for 11-16 hours, and then vulcanize at 85-115°C for 25-45 minutes. In parts by weight, the multifunctional crosslinking agent is 0.8-1.8 parts, sulfur is 0.25-0.45 parts, and the auxiliary agent is 0.8-2.5 parts. The multifunctional crosslinking agent can be selected from one or more of polyacids, polyamines, polyols, etc. The auxiliary agent is a mixture of zinc oxide, stearic acid, and antioxidant 1010.

[0085] Please follow the steps below:

[0086] Step 1: Dissolve 100 parts of polyisoprene rubber in toluene to prepare a 6% concentration of glue solution, add 35 parts of 2-(vinyl ether)-3-methylimidazole and 1.2 parts of dibenzoyl peroxide to the glue solution, and react at 65°C for 11 hours. After the reaction is completed, pour the polymer solution into ethanol to precipitate to obtain modified polyisoprene rubber, wash it with ethanol three times, and then dry it in a 60°C oven to constant weight.

[0087] Step 2: Emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 1.2 parts of hexamethylenediamine, 0.35 parts of sulfur, and 2 parts of additives based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 22°C for 13 hours, pour into a film mold, and then vulcanize at 100°C for 35 minutes to prepare a film product.

[0088] The comparative example adopts the conventional polyisoprene rubber vulcanization process without adding the novel organic compound modifier, and other conditions are the same as those in the embodiment to prepare a film product.

[0089] The film products prepared in the examples and comparative examples were subjected to mechanical property tests, including tensile strength, elongation at break and modulus tests, and the results are shown in the following table:

[0090] Test items Example Comparative Example Tensile strength(MPa) 28 20 Elongation at break (%) 900 700 Modulus (MPa) 4.5 3.2

[0091] From the above data, it can be seen that after using the novel modifier of the present invention, the tensile strength of the modified polyisoprene rubber product increased by 40%, the elongation at break increased by about 28.6%, and the modulus increased by about 40.6%. This shows that 2-(vinyl ether)-3-methylimidazole as a modifier has a significant synergistic effect in improving the vulcanization effect and product performance of polyisoprene rubber.

[0092] Example 7

[0093] A phosphorus-containing organic compound modifier is used.

[0094] The novel phosphorus-containing organic compound modifier used in the present invention is bis(allyl)phenylphosphine oxide. The allyl group: allyl (-CH-CH=CH) has high reactivity and can undergo free radical polymerization under the action of an initiator. It can undergo addition reaction with the double bonds on the polyisoprene rubber molecular chain, thereby introducing the phosphorus-containing group into the rubber molecular chain. This graft copolymerization reaction changes the structure of the rubber molecular chain, increases the branching degree and crosslinking points of the molecular chain, improves the crosslinking density of the rubber, and further improves the mechanical properties of the rubber, such as tensile strength and modulus. At the same time, the introduction of the allyl group also provides more active sites for the subsequent vulcanization reaction, making the vulcanization reaction more sufficient and uniform, and shortening the vulcanization time.

[0095] Phenyl phosphine oxide group: The phosphorus atom in the phenyl phosphine oxide group (-CH-PO) has an empty d orbital, which can interact with the electron cloud in the rubber molecular chain, enhance the attraction between the molecular chains, and improve the stability of the rubber. During the vulcanization process, the phosphorus atom can also react synergistically with sulfur or other crosslinking agents to form a special crosslinking structure, further improving the strength of the crosslinking network of the rubber. In addition, the phenyl phosphine oxide group has good flame retardant properties. It can form a dense phosphorus-containing protective film when the rubber burns, preventing the transfer of oxygen and heat, thereby effectively improving the flame retardancy of rubber products. At the same time, the benzene ring structure in the group has a certain conjugated system, which can absorb and disperse external energy such as ultraviolet rays, giving rubber products better aging resistance.

[0096] A vulcanization method for modified polyisoprene rubber comprises the following steps:

[0097] Step 1: dissolve polyisoprene rubber into a glue solution with a concentration of 2-6%, add the above-mentioned new phosphorus-containing organic compound modifier and initiator to the glue solution, react at 45-65°C for 10-14h to obtain a reaction polymer solution, and then precipitate with an organic solvent to obtain a modified polyisoprene rubber. Among them, by weight, 100 parts of polyisoprene rubber, 30-50 parts of new phosphorus-containing organic compound modifier, and 1-2 parts of initiator. The glue solution solvent can be selected from one or more of cyclohexane, n-hexane, toluene, etc. The organic solvent for precipitation can be selected from one or more of ethanol, methanol, acetone, etc. The initiator can be selected from one or more of azobisisobutyronitrile, benzoyl peroxide, ammonium persulfate, etc.

[0098] Step 2: Emulsify the modified polyisoprene rubber into an emulsion, add a multifunctional crosslinking agent, sulfur and an additive, pre-vulcanize at 15-25°C for 10-15h, and then vulcanize at 80-110°C for 20-40min. In parts by weight, the multifunctional crosslinking agent is 1-2 parts, sulfur is 0.2-0.4 parts, and the additive is 1-3 parts. The multifunctional crosslinking agent can be selected from one or more of polyacids, polyols, polyamines, etc. The additive is a mixture of zinc oxide, stearic acid, and antioxidant 264.

[0099] Please follow the steps below:

[0100] Step 1: Dissolve 100 parts of polyisoprene rubber in cyclohexane to prepare a 4% concentration of glue solution, add 40 parts of bis(allyl)phenylphosphine oxide and 1.5 parts of azobisisobutyronitrile to the glue solution, and react at 55°C for 12 hours. After the reaction is completed, pour the polymer solution into ethanol for precipitation to obtain modified polyisoprene rubber, wash it with ethanol three times, and then dry it in a 50°C oven to constant weight.

[0101] Step 2: Emulsify the dried modified polyisoprene rubber into an emulsion using a conventional emulsification method, add 1.5 parts of trimethylolpropane, 0.3 parts of sulfur, and 2 parts of additives based on the dry basis of the modified polyisoprene rubber obtained in step 1, pre-vulcanize at 20°C for 13 hours, pour into a film mold, and then vulcanize at 95°C for 30 minutes to prepare a film product.

[0102] In the comparative example, a conventional polyisoprene rubber vulcanization process without adding the novel phosphorus-containing organic compound modifier was used, and other conditions were the same as those in the example to prepare a film product.

[0103] The film products prepared in the examples and comparative examples were tested for mechanical properties (tensile strength, elongation at break, modulus), flame retardancy (limiting oxygen index test) and aging resistance (mechanical property retention after accelerated aging). The results are shown in the following table:

[0104]

[0105] From the above data, it can be seen that after using the novel phosphorus-containing organic compound modifier of the present invention, the tensile strength of the modified polyisoprene rubber product is increased by about 44.4%, the elongation at break is increased by about 30.8%, the modulus is increased by about 50%, the limiting oxygen index is increased by 40%, and the tensile strength retention rate after aging is increased by about 33.3%. This shows that bis(allyl)phenylphosphine oxide as a modifier has a significant synergistic effect in improving the vulcanization effect, mechanical properties, flame retardant properties and aging resistance of polyisoprene rubber.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for vulcanizing modified polyisoprene rubber, characterized in that: The following steps are involved: Step 1, dissolving polyisoprene rubber into a 1-10% concentration of glue solution, adding a polar monomer or a novel organic compound modifier to the glue solution, and then adding an initiator, reacting at 60-80° C. for 8-12 hours to obtain a reaction polymer solution, and then precipitating with an organic solvent to obtain a modified polyisoprene rubber; Step 2: emulsify the modified polyisoprene rubber into an emulsion, add a multifunctional crosslinking agent, sulfur and additives, pre-vulcanize at 20-30° C. for 12-17 hours, and then vulcanize at 90-120° C. for 30-50 minutes.

2. A method for vulcanizing modified polyisoprene rubber according to claim 1, characterized in that: In step 1, by weight, 100 parts of polyisoprene rubber, 30-50 parts of polar monomer, and 1-2 parts of initiator are used.

3. The method for vulcanizing modified polyisoprene rubber according to claim 1, characterized in that: In step 1, the glue solvent includes one or more of cyclohexane, n-hexane, toluene and xylene.

4. The method for vulcanizing modified polyisoprene rubber according to claim 1, characterized in that: In step 1, 30-50 parts of a novel organic compound modifier: a silicone-containing acrylic ester compound or 2-(vinyl ether)-3-methylimidazole or bis(allyl)phenylphosphine oxide is added.

5. The method for vulcanizing modified polyisoprene rubber according to claim 1, characterized in that: In step 2, by weight, the multifunctional crosslinking agent is 1-2 parts, sulfur is 0.3-0.5 parts, and the auxiliary agent is 1-3 parts.

6. A method for vulcanizing modified polyisoprene rubber according to claim 2, characterized in that: The polar monomers include one or more of acrylates and their derivatives, acrylic acid and their derivatives, phospholipids and their derivatives, mercapto acids and their derivatives, and mercaptoamines and their derivatives.

7. A method for vulcanizing modified polyisoprene rubber according to claim 2, characterized in that: The initiator includes one or more of azobisisobutyl cyanide, azobisisoheptanenitrile, diisopropylbenzene peroxide, benzoyl peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl hydroperoxide, potassium persulfate, sodium persulfate, and ammonium persulfate.

8. The method for vulcanizing modified polyisoprene rubber according to claim 5, characterized in that: In step 2, the multifunctional cross-linking agent includes one or more of polyacids, polyols, polyamines, and polyepoxides.

9. The method for vulcanizing modified polyisoprene rubber according to claim 5, characterized in that: In step 2, the auxiliary agent is a mixture of zinc oxide, potassium hydroxide, titanium dioxide and antioxidant 264.

10. Use of the vulcanization method of modified polyisoprene rubber according to any one of claims 1 to 9 in modified polyisoprene rubber.

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