Zinc-free vulcanization aid, rubber composition, rubber product, and tire

Abstract

The application provides a zinc-free vulcanization aid, a rubber composition, a rubber product and a tire. The zinc-free vulcanization aid is prepared by the following method: zinc oxide, stearic acid, an antioxidant, a vulcanization system medicine are pre-reacted in a solvent, and after pre-reaction, filtration for removing zinc and solvent removal are sequentially performed to obtain the zinc-free vulcanization aid. The zinc-free vulcanization aid contains an active intermediate generated by pre-reaction, the intermediate has the effect of promoting vulcanization, and plays the role of activating the accelerator in advance, so that it can partially or completely replace the role of zinc oxide in the ordinary formula. The zinc-free rubber product can be prepared by using the zinc-free vulcanization aid, zinc emission is realized, the environment is friendly, and through the action of the zinc-free vulcanization aid, the rubber composition can obtain the rubber properties such as crosslinking density, hardness, modulus, hysteresis and the like close to those of the zinc-containing rubber without containing zinc.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparation of tire tread rubber, in particular to a zinc-free vulcanization aid, rubber composition, rubber product and tire. BACKGROUND

[0002] At present, zinc oxide or zinc-containing aid is indispensable as a rubber vulcanization activator or functional aid in the design of tire formulations. Rubber compositions lacking zinc have low modulus, low modulus, low hardness, and low crosslinking degree; especially in diene rubber compositions containing natural rubber, isoprene rubber, butyl rubber, etc. If zinc oxide is not contained, it will produce a vulcanization reversion effect, and even lead to the complete lack of use value of the rubber compound. Therefore, in general, the zinc oxide in diene rubber compositions used for tire manufacturing is at least 2 phr.

[0003] However, from the aspects of "sustainable development" and environmental protection, zinc oxide in tires will enter the water circulation system with tire wear debris, causing environmental water pollution. The European Commission Directive 2400 / 73 / EC and the SB1260 bill proposed by California in 2016 both suggest limiting the use of zinc or zinc oxide in tires.

[0004] This poses a requirement for zinc-free production for tire manufacturers. However, in the current process, if zinc is completely removed from diene rubber compositions, it will result in a decrease in crosslinking degree, a decrease in rubber hardness and modulus, an increase in hysteresis loss, and a significant decrease in the use value of tires made therefrom.

[0005] In order to achieve the environmental protection goal and ensure the tire performance, some research and development attempts of zinc-free or low-zinc rubber compositions are carried out at home and abroad. Patent CN109369994B discloses a low-zinc rubber composition, which contains 0.5-1 phr of zinc, replaces zinc oxide with high specific surface area nano-zinc oxide taking zinc hydroxide particles as a carrier, reduces the use of zinc on the basis of high activity and high dispersion, and ensures good performance of the composition. Patent CN115678038B discloses a zinc lignin salt compound that replaces zinc oxide, uses the dispersion characteristics of the zinc lignin salt compound to achieve the purpose of reducing the amount of zinc oxide, and is applied to the tire tread rubber to ensure the wear resistance of the tire and reduce the rolling resistance of the tire, and improve the service life of the tire. The above two patents both achieve the purpose of reducing the amount of zinc by improving the dispersion of zinc, but cannot completely eliminate the environmental hazards of zinc. Patent CN102300917B discloses a rubber composition containing no zinc or containing 0.5 phr or less of zinc and applied to tire manufacturing, which uses capped mercaptosilane to improve the processability (i.e. reduce the viscosity and prolong the scorch time) of the rubber composition without zinc. Although the patent can reduce the amount of zinc or even contain no zinc, it needs to use a specific capped mercaptosilane, which may further react to generate mercapto at high temperature mixing, has certain irritancy and odor, and has safety problems. SUMMARY

[0006] The main purpose of the present application is to provide a zinc-free vulcanization aid, a rubber composition, a rubber product and a tire to solve the problem of environmental pollution caused by the presence of zinc in the rubber product used for tire manufacturing in the prior art.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a zinc-free vulcanization aid is provided, which is obtained by the following preparation method: pre-reacting zinc oxide, stearic acid, antioxidant, vulcanization system medicine in a solvent, and then filtering out zinc and removing the solvent to obtain the zinc-free vulcanization aid.

[0008] Further, the reaction temperature of the pre-reaction is 100-190 °C, and the reaction time is 1 min-120 min.

[0009] Preferably, the reaction temperature of the pre-reaction is 110-170 °C, and the reaction time is 5 min-50 min.

[0010] Further, 10-20 phr of zinc oxide, 5-15 phr of stearic acid, 5-15 phr of antioxidant and 5-15 phr of vulcanization system medicine are added in the pre-reaction.

[0011] Furthermore, the solvent is selected from any one or more of butanol, octanol, N-methylpyrrolidone, octane, nonane, decane, toluene, and xylene;

[0012] And / or, the antioxidant is a p-phenylenediamine antioxidant;

[0013] And / or, the vulcanization system reagents added in the pre-reaction include any one or more of vulcanizing agents and accelerators. Vulcanizing agents include any one or more of sulfur-based and sulfur carrier-based agents. Accelerators include any one or more of sulfenamide-based and thiazole-based accelerators. Preferably, the accelerators include any one or more of CZ, DCBS, MBTS, MBT, and TBBS.

[0014] Furthermore, the antioxidant includes compounds having the structure shown in Formula I:

[0015] Formula I

[0016] In formula I, R 1 Selected from C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 aromatic group, R 2 R 3 R 4 R 5 Each independently selected from C1-C 18 The chain hydrocarbon group, R 2 With R 3 Or R 4 With R 5 They can also form adipose rings individually or simultaneously, R 6 Selected from H, C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 The aromatic group; x=0 or 1, y=0 or 1, z=0 or 1, w=0 or 1, and at least one of x and w is 1, and at least one of y and z is 1.

[0017] Furthermore, the zinc-free vulcanizing aid also includes 50-150 phr of rubber. The preparation method of the zinc-free vulcanizing aid including rubber further includes a first mixing or a second mixing. The first mixing includes: mixing the filtrate obtained after zinc removal by filtration with the rubber and then removing the solvent; the second mixing includes: removing the solvent from the filtrate obtained after zinc removal by filtration and then mixing it with the rubber.

[0018] Preferably, the rubber comprises any one or more of natural polymers or synthetic polymers, preferably the rubber is selected from any one or more of natural rubber, styrene butadiene rubber, isoprene rubber, natural gutta-percha, polyisoprene rubber, butadiene rubber, halogenated butyl rubber and ethylene propylene diene rubber; preferably the rubber has a molecular weight of 1 kilo to 40 million, further preferably 5 kilo to 30 million, more preferably 1 million to 8 million.

[0019] Preferably, the rubber comprises a diene rubber having the following structure of Formula II:

[0020] Formula II

[0021] wherein a, b, c, d, e and f are each independently an integer greater than or equal to 0, and a, b, c, d, e and f are not simultaneously 0.

[0022] According to another aspect of the present application, there is provided a rubber composition comprising: an elastomer, a filler and a zinc-free curing aid, the zinc-free curing aid being any one of the zinc-free curing aids described above.

[0023] Further, the filler comprises any one or more of carbon-based fillers, silicon-based fillers, carbon-silicon dual-phase fillers and clays;

[0024] Preferably, the filler has a specific surface area of 10 to 500 m 2 / g, further preferably 30 to 300 m 2 / g, more preferably 50 to 300 m 2 / g.

[0025] Further, the rubber composition comprises 100 phr of the elastomer, 20 phr to 170 phr of the filler and 10 to 50 phr of the zinc-free curing aid;

[0026] Preferably, the rubber composition comprises 3 to 30 parts of other additives, the other additives being selected from any one or more of resins, processing oils, vulcanizing agents and silane coupling agents.

[0027] According to yet another aspect of the present application, there is provided a rubber article prepared from a rubber composition, the rubber composition comprising any one of the rubber compositions described above.

[0028] According to still another aspect of the present application, there is provided a tire comprising the rubber article described above.

[0029] The application discloses a zinc-free vulcanization aid, a rubber composition, a rubber product and a tire. DETAILED DESCRIPTION

[0030] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0031] As analyzed in the background art of the present application, there is a problem of environmental pollution caused by zinc contained in rubber products for tire preparation in the prior art. The lack of zinc in the existing tire rubber formula will cause a significant decrease in the performance of rubber, which is difficult to meet the use requirements. In order to solve this problem, the present application provides a zinc-free vulcanization aid, a rubber composition, a rubber product and a tire.

[0032] According to a typical embodiment of the present application, a zinc-free vulcanization aid is provided, which is prepared by the following preparation method: zinc oxide, stearic acid, antioxidant, vulcanization system medicine are pre-reacted in a solvent, and after pre-reaction, zinc is removed by filtration, and the solvent is removed to obtain the zinc-free vulcanization aid.

[0033] The zinc-free vulcanization aid contains active intermediates generated by pre-reaction of antioxidants and vulcanization system medicines under the catalysis of zinc oxide and stearic acid. The intermediates have the effect of promoting vulcanization and play the role of activating the accelerator in advance, so they can partially or completely replace zinc oxide in the general formula. The zinc-free vulcanization aid can be used to prepare zinc-free rubber products, realize zinc-free emission, and be friendly to the environment. Moreover, through the action of the zinc-free vulcanization aid, the rubber composition can obtain crosslinking density and hardness, modulus, hysteresis and other properties close to those of zinc-containing rubber without containing zinc.

[0034] Taking phenylenediamine antioxidants and 2-thiobenzothiazole vulcanization system medicines as examples, the reaction occurring in the pre-reaction is shown in the following reaction equation, and the generated active intermediates have the effect of promoting vulcanization.

[0035]

[0036] In some embodiments of the present application, the pre-reaction temperature is 100-190 °C and the reaction time is 1 min-120 min, which can promote the reaction between the antioxidant and the vulcanization system, and the pre-reaction product has a good effect of promoting vulcanization, which is beneficial to further improve the performance of the rubber composition containing the same. Preferably, the pre-reaction temperature is 110-170 °C, such as 120 °C, 130 °C, 140 °C, 150 °C, 160 °C or 170 °C, and the pre-reaction effect is better, and preferably, the pre-reaction time is 5 min-50 min, such as 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min or 50 min.

[0037] The proportions of zinc oxide, stearic acid, antioxidant and vulcanization system added in the pre-reaction can be set according to the proportions of the corresponding components in the existing formula. In some typical embodiments of the present application, 10-20 phr of zinc oxide, 5-15 phr of stearic acid, 5-15 phr of antioxidant and 5-15 phr of vulcanization system are added in the pre-reaction, and the zinc-free vulcanization aid prepared has a more significant promoting effect on improving the crosslinking density of the composition and the performance of the rubber compound.

[0038] In some embodiments of the present application, the antioxidant in the pre-reaction is a p-phenylenediamine antioxidant, for example, any one or more of 4020 (6PPD), 4010NA (IPPD) and 7PPD.

[0039] In some preferred embodiments of the present application, the antioxidant in the zinc-free vulcanization aid is an environmentally friendly p-phenylenediamine antioxidant, which not only has a good effect, but also is more environmentally friendly, and its structural formula is as follows:

[0040]

[0041] In the formula, R 1 is a chain hydrocarbon group, a cycloaliphatic hydrocarbon group or an aromatic hydrocarbon group, R 18 is a chain hydrocarbon group, a cycloaliphatic hydrocarbon group or an aromatic hydrocarbon group, R 18 is a chain hydrocarbon group, a cycloaliphatic hydrocarbon group or an aromatic hydrocarbon group, R 18 is a chain hydrocarbon group, a cycloaliphatic hydrocarbon group or an aromatic hydrocarbon group, R 2 , R 3 , R 4 , R 5 are each independently a chain hydrocarbon group, R 18 and R 2 or R 3 and R 4 or R 5 may also form an aliphatic ring respectively or simultaneously, and R 6 is selected from H, a chain hydrocarbon group, a cycloaliphatic hydrocarbon group or an aromatic hydrocarbon group, R 18C1-C10alkyl, C3-C10 18 C6-C10cycloalkyl, or C6-C10 18 aromatic hydrocarbon group; x = 0 or 1, y = 0 or 1, z = 0 or 1, w = 0 or 1, and at least one of x and w is 1, and at least one of y and z is 1.

[0042] In some embodiments of the present application, the vulcanization system additives added in the pre-reaction include any one or more of vulcanizing agents and accelerators. In other embodiments of the present application, the vulcanization system additives added in the pre-reaction are any one or more of accelerators, and the vulcanizing agents are added in the process of preparing the rubber product. Preferably, the vulcanizing agents include any one or more of sulfur and sulfur carriers.

[0043] Preferably, the accelerators include any one or more of sulfenamide accelerators and thiazole accelerators. Preferably, the accelerators include any one or more of CZ, DCBS, MBTS, MBT and TBBS.

[0044] The zinc oxide and stearic acid added in the pre-reaction can be selected from the prior art, and the present application does not have special requirements.

[0045] The solvent in the pre-reaction can dissolve the stearic acid, anti-aging agents and vulcanization system additives involved in the pre-reaction, and does not dissolve the zinc oxide, and has no adverse effect on the reaction of the anti-aging agents and the vulcanization system additives, and can be selected from the prior art. The amount of the solvent added can be adjusted according to its solubility for the above pre-reaction raw materials. Preferably, the solvent is selected from any one or more of butanol, octanol, N-methyl pyrrolidone, octane, nonane, decane, toluene and xylene, which not only has good solubility for the stearic acid, anti-aging agents and vulcanization system additives, is convenient for subsequent separation, but also is conducive to the pre-reaction and improves the reaction efficiency.

[0046] Since the zinc oxide is not dissolved in the solvent, after the pre-reaction is completed, the zinc oxide in the product system obtained after the pre-reaction can be removed by filtration, and other effective components remain in the filtrate, which well separates the zinc oxide and avoids zinc residue.

[0047] In some typical embodiments of the present application, the zinc-free vulcanization aid further comprises 50-150 phr of rubber, and the preparation method of the zinc-free vulcanization aid comprising rubber further comprises a first mixing or a second mixing, wherein the first mixing comprises mixing the filtrate obtained after the zinc removal with the rubber and removing the solvent; and the second mixing comprises mixing the filtrate obtained after the zinc removal with the rubber after removing the solvent. The zinc-free vulcanization aid comprising rubber is a masterbatch type aid, and the dispersion has been achieved in the rubber, so that the effect is better in subsequent application, and it is more conducive to the exertion of the active intermediates generated by the pre-reaction of the antioxidant and the vulcanization system on the crosslinking density and the improvement of the rubber compound. In particular, in the first mixing, the filtrate obtained after the zinc removal and the rubber can be uniformly mixed by a relatively simple method, such as stirring, and the rubber and other components are more fully and uniformly mixed; in the second mixing, the zinc-removed product after removing the solvent and the rubber can be mixed by the mixing method in the prior art, such as mixing.

[0048] Further, the rubber includes any one or more of natural polymers or synthetic polymers. The natural polymers include, but are not limited to, natural rubber, gutta-percha, silver camphor gum, etc. The synthetic polymers include, but are not limited to, polymers obtained by polymerization of monomers in a solution (i.e., solution polymerized rubber), polymers obtained by polymerization of monomers in an emulsion (i.e., emulsion polymerized rubber), and polymers obtained by polymerization of monomers in bulk. The solution polymerized rubber is a homopolymer or a copolymer of ethylene, propylene, butene, pentene, hexene, heptene, dienes with 4-7 carbon atoms, or trienes with 6-7 carbon atoms, or olefin monomers containing other atoms or functional groups, including any one or more of silicon atoms, fluorine atoms, chlorine atoms, nitrogen atoms, oxygen atoms, sulfur atoms, ester groups, amino ester groups, and cyano groups, and also includes homopolymers and copolymers containing the above-mentioned monomers, including but not limited to polybutadiene, polyisoprene, styrene-butadiene rubber, ethylene-propylene rubber, butyl rubber, nitrile-butadiene rubber, chlorobutyl rubber, silicone rubber, fluororubber, polyurethane rubber, chlorosulfonated polyethylene rubber, and acrylate rubber, etc.

[0049] The rubber in the zinc-free vulcanization aid of the present application is preferably any one or more of natural rubber, styrene-butadiene rubber, isoprene rubber, natural gutta-percha, polyisoprene rubber, butadiene rubber, halogenated butyl rubber, and terpolymer ethylene-propylene rubber.

[0050] In some embodiments of the present application, the rubber in the zinc-free vulcanization aid is preferably diene rubber, preferably the diene rubber structure contains branched chains and / or side groups, and the branched chains and / or side groups contain olefinic double bonds and / or aromatic groups.

[0051] In some embodiments of the present application, the rubber in the zinc-free vulcanization aid is diene rubber comprising the following structure II;

[0052] Formula II

[0053] In Formula II, a, b, c, d, e and f are each independently an integer greater than or equal to 0, and a, b, c, d, e and f are not simultaneously 0.

[0054] Preferably, at least two of a, b, c, d, e and f are not 0. The repeating units are randomly distributed.

[0055] In some preferred embodiments of the present application, the diene-based rubber having Formula II structure, a, b, c are 0, d, e, f are not 0; or a, b, c are not 0, d, e, f are 0; or a, b, c, d are 0, e, f are not 0; the diene-based rubber having the structure has higher crosslinking density.

[0056] Further, the sum of the number of alkenyl double bonds and aromatic groups on the side groups and branches of the diene-based rubber of Formula II is more than 15% of the sum of the number of alkenyl double bonds and aromatic groups of the rubber, such as 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 90% or any range between any two of them. Those skilled in the art can understand that Formula II structure can only contain side groups or branches, and can only contain alkenyl double bonds or aromatic groups on the side groups or branches. The number of alkenyl double bonds or aromatic groups on the side groups or branches is more than 15% of the sum of the number of alkenyl double bonds and aromatic groups in the molecular structure of the diene-based rubber.

[0057] Preferably, the molecular weight of the rubber of Formula II structure is 10,000-4,000,000.

[0058] Further, the rubber of Formula II structure is more than 35% by weight of the diene-based rubber, preferably more than 60% by weight of the diene-based rubber, such as 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% by weight of the diene-based rubber.

[0059] According to another aspect of the present application, a rubber composition is provided, which comprises: an elastomer, a filler and a zinc-free vulcanization aid, wherein the zinc-free vulcanization aid is any one of the above-mentioned zinc-free vulcanization aids.

[0060] The rubber composition of the present application uses the zinc-free curing aid, and thus can be prepared into a zinc-free rubber product, and realizes zinc-free emission, which is friendly to the environment. Moreover, through the action of the zinc-free curing aid, the rubber composition can obtain the similar crosslinking density and hardness, modulus, hysteresis and other properties of the rubber composition containing zinc.

[0061] The elastomer in the rubber composition can be selected from the prior art, and can be the same as or different from the rubber in the zinc-free curing aid, and is not particularly limited, and will not be described here.

[0062] The filler in the rubber composition includes any one or more of carbon-based fillers, silicon-based fillers, carbon-silicon dual-phase fillers, and clays; preferably, the specific surface area of the filler is 10-500 m 2 / g, further preferably 30-300 m 2 / g, and more preferably 50-300 m 2 / g, which is helpful to improve the properties of the rubber composition.

[0063] In some typical embodiments of the present application, in order to better exert the synergistic effect of the components, the rubber composition includes 100 phr of elastomer, 20-170 phr of filler, and 10-50 phr of zinc-free curing aid. Preferably, the rubber composition includes 100 phr of elastomer, 50-130 phr of filler, and 20-35 phr of zinc-free curing aid.

[0064] The rubber composition of the present application can include a vulcanizing agent, which can be added to the pre-reaction for preparing the zinc-free curing aid as one of the vulcanizing system drugs, or can be separately included in the rubber composition.

[0065] In some preferred embodiments of the present application, the rubber composition includes 3-30 parts of other auxiliary agents selected from any one or more of resins, operating oils, vulcanizing agents, and silane coupling agents.

[0066] According to another typical embodiment of the present application, a rubber product is provided, which is prepared from the rubber composition, wherein the rubber composition includes any one of the rubber compositions described above.

[0067] The rubber product is prepared from the above-mentioned rubber composition without zinc, which not only realizes zero zinc emission, but also has rubber compound properties such as crosslinking density and hardness, modulus, hysteresis close to those of a rubber composition containing zinc.

[0068] The method for preparing the rubber product by mixing the above-mentioned rubber composition can be selected in the prior art, and no special requirements are provided in the present application.

[0069] In some preferred embodiments of the present application, the vulcanization system drug added in the preparation of the zinc-free vulcanization aid is an accelerator, and the above-mentioned rubber product is prepared by the following method using the zinc-free vulcanization aid: (a) mixing the elastomer, the filler, the zinc-free vulcanization aid and the optional other additives by kneading in one or more times, and the mixing temperature is 125 °C to 200 °C to remove the gum as a first-stage masterbatch; (b) performing one or more times of hot mechanical kneading on the first-stage masterbatch, and keeping the kneading temperature at 125 °C to 180 °C to remove the gum for 0 to 1200 s to obtain a second-stage masterbatch; if there are remaining other additives, fillers and anti-aging agents, they are all added at this stage in one or more times; and (c) mixing the second-stage masterbatch with the vulcanization system in a mixer to obtain a final compound. In the above-mentioned method, specific mixing conditions are used according to the zinc-free vulcanization aid, which can further improve the performance of the prepared rubber product. Preferably, the final compound prepared by the above-mentioned process is vulcanized on a flat vulcanizing machine to obtain a vulcanized rubber.

[0070] According to another typical embodiment of the present application, a tire containing the above-mentioned rubber product is provided. The tire has good performance and can realize zero or greatly reduced zinc emission due to the use of the above-mentioned rubber product, and has good application prospects.

[0071] The beneficial effects that can be achieved by the present application will be further illustrated below in combination with examples and comparative examples.

[0072] The sources or technical parameters of the raw materials or reagents used in the examples and comparative examples are as follows:

[0073] IR, Qingdao Yikesi New Material Co., Ltd.;

[0074] White carbon black, NEWSIL1165-MP, Wuxi QuCheng Silicon Industry Co., Ltd.;

[0075] Carbon black, N234, Shandong Zhongxiao High Polymer Material Co., Ltd.;

[0076] Silane coupling agent Si69, Nanjing Shuguang Chemical Group Co., Ltd.;

[0077] SSBR, Dushanzi Petrochemical (styrene 25%, vinyl 64%);

[0078] SBR, Qilu Petrochemical ESBR1502 (styrene content 23.5%);

[0079] BR, Qilu Petrochemical BR9000 (nickel-based high-cis butadiene, cis content 97%);

[0080] NR, Xishuangbanna Michelin Rubber Co., Ltd. SCR5;

[0081] Stearic acid, PF1808, Malaysia Li Cheng Co., Ltd.;

[0082] Zinc oxide, Dalian Zinc Oxide Factory;

[0083] Antioxidant 4020, Jiangsu Shengao Chemical Co., Ltd.;

[0084] Antioxidant 4010NA, Shandong Shangshun Chemical Co., Ltd.;

[0085] Antioxidant 7PPD, Jiangsu Shengao Chemical Co., Ltd.;

[0086] Antioxidant A, self-synthesized, the structure is ;

[0087] Antioxidant B, self-synthesized, the structure is ;

[0088] Antioxidant C, self-synthesized, the structure is ;

[0089] Antioxidant D, self-synthesized, the structure is ;

[0090] Antioxidant E, self-synthesized, the structure is ;

[0091] Antioxidant F, self-synthesized, the structure is ;

[0092] Promoter CZ, Shandong Shangshun Chemical Co., Ltd.;

[0093] Promoter TBBS, Shandong Shangshun Chemical Co., Ltd.;

[0094] Promoter MBTS, Chaoyang Tianming Industry and Trade Co., Ltd.;

[0095] Promoter DPG, Shandong Shunxian Chemical Co., Ltd.;

[0096] Sulfur, no. Dijinsheng Chemical Co., Ltd.

[0097] Example 1

[0098] Mix 10 phr stearic acid, 17.5 phr zinc oxide, 10 phr antioxidant 4020, 10 phr vulcanization accelerator TBBS in decane, pre-react at 160 °C for 30 min, filter out the zinc oxide after the temperature returns to room temperature, dry the filtrate, and mix with 96.3 phr SSBR, 30 phr BR to obtain a zinc-free curing aid;

[0099] Prepare the rubber compound according to the formulation in Table 1, and the specific method is as follows:

[0100] After kneading the SSBR and BR in the internal mixer, add carbon black N234, the above-mentioned zinc-free curing aid, and continue to knead until uniform, and control the temperature during kneading at 150-160 °C;

[0101] Add sulfur, knead, and control the temperature during kneading at no more than 110 °C;

[0102] Vulcanize the obtained rubber composition to obtain a vulcanized rubber, and test the physical properties of the rubber compound.

[0103] Comparative Example 1

[0104] Prepare the rubber compound according to the formulation in Table 1, and the specific method is as follows:

[0105] After kneading the SSBR and BR in the internal mixer, add carbon black N234, stearic acid, zinc oxide, antioxidant 4020, and accelerator TBBS, and continue to knead until uniform, and control the temperature during kneading at 150-160 °C;

[0106] Add sulfur, knead, and control the temperature during kneading at no more than 110 °C;

[0107] Vulcanize the obtained rubber composition to obtain a vulcanized rubber, and test the physical properties of the rubber compound.

[0108] Example 2

[0109] Mix 10 phr stearic acid, 17.5 phr zinc oxide, 12.5 phr antioxidant A, and 11.5 phr vulcanization accelerator CZ in xylene, pre-react at 130 °C for 40 min, filter out the zinc oxide after the temperature returns to room temperature, dry the filtrate, and mix with 100 phr IR to obtain a zinc-free curing aid;

[0110] Prepare the rubber compound according to the formulation in Table 1, and the specific method is as follows:

[0111] After kneading the IR in the internal mixer, add white carbon black, Si69, and the above-mentioned zinc-free curing aid, and continue to knead until uniform, and control the temperature during kneading at 150-160 °C;

[0112] Sulfur, DPG were added, kneaded, the temperature during kneading was not more than 120 °C.

[0113] The obtained rubber composition was vulcanized to obtain vulcanized rubber, and the physical properties of the rubber were tested.

[0114] Comparative Example 2

[0115] The rubber was prepared according to the formulation in Table 1, and the specific method was as follows:

[0116] After the IR was kneaded in the internal mixer, the white carbon black, Si69, stearic acid, zinc oxide, antioxidant A, and accelerator CZ were added, and the kneading was continued until the mixture was uniform, and the temperature during kneading was controlled at 150-160 °C.

[0117] Sulfur, DPG were added, kneaded, the temperature during kneading was not more than 120 °C.

[0118] The obtained rubber composition was vulcanized to obtain vulcanized rubber, and the physical properties of the rubber were tested.

[0119] Comparative Examples 0-1 and 0-2 were set as zero-zinc blank samples, and the difference between Comparative Examples 0-1 and 0-2 and Comparative Examples 1 and 2 was that no zinc oxide was added in Comparative Examples 0-1 and 0-2.

[0120] Table 1 Rubber formulation (unit: phr)

[0121]

[0122] The zinc content in the rubber was determined according to "SN / T 2945-2011 Determination of Lead, Cadmium, Chromium, Copper, Manganese and Zinc in Rubber and Rubber Products by Inductively Coupled Plasma Atomic Emission Spectrometry", and the test results are shown in Table 2.

[0123] The vulcanization characteristics of the rubber were determined according to "GB / T 16584-1996 Rubber Determination of Vulcanization Characteristics by Means of a Moving Die Vulcanization Press", and the test results are shown in Table 3.

[0124] The physical properties (tensile strength, elongation at break, 100% modulus, and 300% modulus) of the rubber were determined according to "GB / T 528-2009 Vulcanized Rubber or Thermoplastic Rubber Determination of Tensile Stress-Strain Properties", and the results are shown in Table 3.

[0125] The hardness of the rubber was determined according to "GB / T 531.1-2008 Vulcanized Rubber or Thermoplastic Rubber Determination of Indentation Hardness Test Methods Part 1: Durometer Method (Shore Hardness)", and the test results are shown in Table 3.

[0126] The modulus at 20℃ of the rubber compound was determined according to GB / T 9870.1-2006 Rubber, vulcanized or thermoplastic - Determination of dynamic properties - Part 1: General test method, and tan delta max of the rubber compound was determined by using a rotational rheometer. The test results are shown in Table 3.

[0127] Table 2

[0128]

[0129] As can be seen from the results in Table 2, the zinc content in the rubber composition containing zinc-free vulcanization aid is comparable to that in the zero-zinc blank sample without adding zinc oxide, and is significantly lower than that in the ordinary zinc-containing formula.

[0130] In Table 3 and the subsequent physical property test result table, in order to facilitate comparison, the test data of each example are obtained by taking the corresponding comparative example with the same composition except for zinc oxide as the benchmark, and the index value is obtained, for example, in Table 1, the value of MH of Example 1 is the ratio of the measured value of Example 1 to the measured value of Comparative Example 1 x 100; the larger the value, the higher the index.

[0131] Table 3 Physical property test results

[0132]

[0133] As can be seen from the results in Table 3, the rubber compounds prepared from the zinc-free rubber composition of the present application (Examples 1 and 2) have similar crosslinking density, modulus, stress, hardness, mechanical properties and hysteresis properties to those of the conventional zinc-containing rubber compounds (Comparative Examples 1 and 2), and can be used in rubber products and tires.

[0134] The zinc-free vulcanization aids numbered #3~#9 were prepared, and the amounts of the specific components involved in the preparation process are shown in Table 4, and the process parameters are shown in Table 5. The preparation process is as follows: stearic acid, zinc oxide, antioxidant, vulcanization accelerator are mixed in a solvent, pre-reacted for a period of time, after the temperature returns to room temperature, the zinc oxide is filtered out, the filtrate is first subjected to solvent removal, and then mixed with rubber (#5~#9), or subjected to liquid-phase mixing with rubber (#3~#4), to obtain the zinc-free vulcanization aid. It is determined that the zinc content of the zinc-free vulcanization aids #3~#9 is 0.

[0135] The zinc-free vulcanization aids numbered #10~#14 were prepared, and the formulations and preparation processes thereof are the same as those of Example zinc-free vulcanization aid #6, and the only difference is the pre-reaction parameter condition listed in Table 5. It is determined that the zinc content of the zinc-free vulcanization aids #10~#14 is 0.

[0136] Table 4

[0137]

[0138] Table 5

[0139]

[0140] Examples 3-9 and Comparative Examples 3-9 were prepared according to the same method as Example 1, and the formulations are shown in Tables 6 and 7.

[0141] Table 6 Formulation (unit: phr)

[0142]

[0143] Table 7 Formulation (unit: phr)

[0144]

[0145] Examples 10-14 were prepared according to the same method as Example 1, and the formulations were the same as Example 6 except that the zinc-free vulcanization aid was replaced by zinc-free vulcanization aids #10-#14.

[0146] Examples 3-14 and Comparative Examples 3-9 were tested according to the same test method as Example 1, and the results are shown in Tables 8 and 9.

[0147] Table 8 Physical property test results

[0148]

[0149] Table 9 Physical property test results

[0150]

[0151] Table 10 Physical property test results

[0152]

[0153] In Tables 8 and 9, the rubber formulations containing zinc-free vulcanization aids prepared according to the present application (Examples 3-9) and conventional rubber formulations containing zinc (Comparative Examples 3-9) both meet the performance requirements after vulcanization testing, and can be applied to the production of rubber products and tires. The vulcanized rubber formulations of Examples 2, 5-14 above were aged and extracted, and the extract was detected by ultra-high performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS / MS). No quinone compounds were detected, proving that the environmentally friendly p-phenetidine anti-aging agents A-F used do not produce high-toxicity quinone conversion products in rubber residues, and are an environmentally friendly rubber additive.

[0154] In Table 10, when preparing the zinc-free vulcanization aid, higher temperature and suitable pre-reaction time are beneficial to improve the performance thereof, so that the rubber compound containing the same has more excellent performance.

[0155] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects: the above-mentioned zinc-free vulcanization aid contains active intermediates generated by pre-reaction of the antioxidant and the vulcanization system drug under the catalysis of zinc oxide and stearic acid, the intermediates have the effect of promoting vulcanization, and play the role of activating the accelerator in advance, so that they can partially or completely replace zinc oxide in the ordinary formula. By using the zinc-free vulcanization aid, zinc-free rubber products can be prepared, zinc emission is realized, and the environment is friendly. Moreover, through the action of the above-mentioned zinc-free vulcanization aid, the rubber composition can obtain rubber properties such as crosslinking density and hardness, modulus, hysteresis close to those of zinc-containing rubber without containing zinc.

[0156] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A zinc-free vulcanization aid, characterized by, The zinc-free vulcanization aid is prepared by the following method: zinc oxide, stearic acid, antioxidant, vulcanization system medicine are pre-reacted in a solvent, and then the zinc oxide is removed by filtration, and the solvent is removed to obtain the zinc-free vulcanization aid. In the pre-reaction, 10-20 phr of zinc oxide, 5-15 phr of stearic acid, 5-15 phr of antioxidant, and 5-15 phr of vulcanization system medicine are added. The reaction temperature of the pre-reaction is 100-190°C, and the reaction time is 1 min-120 min. The antioxidant is a p-phenylenediamine antioxidant; the vulcanization system medicine added in the pre-reaction includes an accelerator, and the accelerator includes any one or more of CZ, DCBS, MBTS, MBT, and TBBS.

2. The zinc-free vulcanization aid according to claim 1, characterized in that The reaction temperature of the pre-reaction is 110-170°C, and the reaction time is 5 min-50 min.

3. The zinc-free vulcanization aid according to claim 1, characterized in that The solvent is selected from any one or more of butanol, octanol, N-methyl pyrrolidone, octane, nonane, decane, toluene, and xylene.

4. The zinc-free vulcanization aid according to claim 1, characterized in that The antioxidant includes a compound having a structure shown in Formula I: Formula I In formula I, R 1 Selected from C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 aromatic group, R 2 R 3 R 4 R 5 Each independently selected from C1-C 18 The chain hydrocarbon group, R 2 With R 3 Or R 4 With R 5 They can also form adipose rings individually or simultaneously, R 6 Selected from H, C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 The aromatic group; x=0 or 1, y=0 or 1, z=0 or 1, w=0 or 1, and at least one of x and w is 1, and at least one of y and z is 1.

5. The zinc-free vulcanization aid according to claim 1, characterized in that The zinc-free vulcanization aid further includes 50-150 phr of rubber, and the preparation method of the zinc-free vulcanization aid including the rubber further includes a first mixing or a second mixing.

6. The zinc-free vulcanization aid according to claim 5, characterized in that The rubber includes any one or more of a natural polymer or a synthetic polymer.

7. The zinc-free vulcanization aid according to claim 5, characterized in that The rubber is selected from any one or more of natural rubber, styrene-butadiene rubber, isoprene rubber, natural eucommia rubber, polyisoprene rubber, butadiene rubber, halogenated butyl rubber, and ternary ethylene-propylene rubber.

8. The zinc-free vulcanization aid according to claim 5, characterized in that The molecular weight of the rubber is 1 thousand-40 million.

9. The zinc-free vulcanization aid according to claim 5, characterized in that, The molecular weight of the rubber is 5 thousand-300 million.

10. The zinc-free vulcanization aid according to claim 5, characterized in that, The molecular weight of the rubber is 1 million-800 million.

11. The zinc-free vulcanization co-agent of claim 5, wherein, The rubber includes diene rubber having a structure shown in Formula II: Formula II a, b, c, d, e, and f are each independently an integer greater than or equal to 0, and a, b, c, d, e, and f are not 0 at the same time.

12. A rubber composition characterized in that, The rubber composition includes 100 phr of an elastomer, 20 phr-170 phr of a filler, and 10-50 phr of a zinc-free vulcanization aid. The rubber composition includes 3-30 parts of other aids selected from any one or more of a resin, an operating oil, a vulcanizing agent, and a silane coupling agent.

13. The rubber composition according to claim 12, characterized in that, The rubber composition includes any one or more of the rubber compositions of claims 12-18.

14. The rubber composition according to claim 13, characterized in that, The specific surface area of the filler is 10 to 500 m 2 / g.

15. The rubber composition of claim 13, wherein The specific surface area of the filler is 30 to 300 m 2 / g.

16. The rubber composition of claim 13, wherein The specific surface area of the filler is 50-300 m 2 / g.

17. The rubber composition of claim 12, wherein The rubber product includes the rubber product of claim 19.

18. The rubber composition of claim 17, wherein ​ 19. A rubber article prepared from a rubber composition, characterized in that, ​ 20. A tire characterized by ​

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