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

Abstract

The invention provides a zinc-free vulcanizing aid, a rubber composition, a rubber product and a tire. The preparation method of the zinc-free vulcanizing aid comprises the following steps: pre-reacting zinc oxide, stearic acid, an anti-aging agent and a vulcanizing system drug in a solvent, and sequentially filtering to remove zinc and removing the solvent after the pre-reaction to obtain the zinc-free vulcanizing aid. The zinc-free vulcanizing auxiliary agent contains the intermediate which is active through pre-reaction, and the intermediate has the effect of promoting vulcanization and has the effect of activating an accelerant in advance, so that the zinc-free vulcanizing auxiliary agent can partially or completely replace zinc oxide in a common formula. A zinc-free rubber product can be prepared by adopting the zinc-free vulcanizing aid, zinc-free emission and environmental friendliness are realized, and a rubber composition can obtain rubber properties, such as crosslinking density, hardness, stress at definite elongation, hysteresis and the like, which are close to those of zinc-containing rubber under the condition that zinc is not contained under the action of the zinc-free vulcanizing aid.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of tread rubber, and in particular to a zinc-free vulcanizing aid, a rubber composition, a rubber product and a tire. Background Art

[0002] In the current industry, zinc oxide or zinc-containing additives are indispensable as rubber vulcanization activators or functional additives in tire formulation design. Rubber compositions lacking zinc have low tensile stress, low modulus, low hardness, and low crosslinking degree; especially if diene rubber compositions containing natural rubber, isoprene rubber, butyl rubber, etc. do not contain zinc oxide, vulcanization reversion effect will occur, and even make the rubber completely worthless. Therefore, generally speaking, the zinc oxide content in diene rubber compositions used in tire manufacturing is at least 2phr.

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

[0004] Therefore, the tire manufacturers are required to produce without zinc. However, in the current process, if zinc is completely removed from the diene rubber composition, the degree of crosslinking will be reduced, the hardness and tensile stress of the rubber will decrease, and the hysteresis loss will increase, which will greatly reduce the use value of the tires made with it.

[0005] In order to achieve environmental protection goals and ensure tire performance at the same time, some attempts to develop zinc-free or low-zinc rubber compositions have been carried out at home and abroad. Patent CN109369994B discloses a low-zinc rubber composition, which discloses a rubber composition with a zinc content of 0.5 to 1 phr. It replaces zinc oxide with high specific surface area nano zinc oxide with zinc hydroxide particles as a carrier. On the basis of high activity and high dispersion, it reduces the use of zinc and ensures good performance of the composition. Patent CN115678038B discloses a method of using a lignin zinc salt complex to replace zinc oxide. By utilizing its good dispersion characteristics, it achieves the purpose of reducing the application of zinc oxide, and is applied to tire tread rubber, which can ensure the wear resistance of the tire and reduce the rolling resistance of the tire, thereby increasing the service life of the tire. Both of the above patents achieve the purpose of reducing the application by improving the dispersion of zinc, and cannot completely eliminate the harm of zinc to the environment. Patent CN102300917B discloses a rubber composition that does not contain zinc or contains less than 0.5 phr of zinc and is used in tire manufacturing. It improves the processability of the rubber composition due to the absence of zinc (i.e., reduces viscosity and prolongs scorch time) by using blocked mercaptosilane. Although this patent can reduce the amount of zinc or even contain no zinc, it requires the use of specific blocked mercaptosilane, which may further react to form mercapto groups during high-temperature mixing, has certain irritation and odor, and poses safety issues. Summary of the invention

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

[0007] In order to achieve the above-mentioned object, according to one aspect of the present invention, a zinc-free vulcanization accelerator is provided. The zinc-free vulcanization accelerator is obtained by the following preparation method: zinc oxide, stearic acid, an antioxidant, and a vulcanization system chemical are pre-reacted in a solvent, and after the pre-reaction, the zinc is removed by filtering and the solvent is removed in sequence to obtain the zinc-free vulcanization accelerator.

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

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

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

[0011] Further, 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 chemicals added in the pre-reaction include any one or more of vulcanizing agents and accelerators, the vulcanizing agents include any one or more of sulfurs and sulfur carriers, the accelerators include any one or more of sulfonamide accelerators and thiazole accelerators, preferably, the accelerators include any one or more of CZ, DCBS, MBTS, MBT and TBBS.

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

[0015]

[0016] In Formula I, R 1 Selected from C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 The aromatic hydrocarbon 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 aliphatic rings separately or simultaneously, R 6 Selected from H, C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 an 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 has a value of 1, and at least one of y and z has a value of 1.

[0017] Furthermore, the zinc-free vulcanization accelerator also includes 50 to 150 phr of rubber, and the preparation method of the zinc-free vulcanization accelerator including rubber also includes a first mixing or a second mixing, wherein the first mixing includes: mixing the filtrate obtained after filtering and removing zinc with the rubber and then removing the solvent; the second mixing includes: removing the solvent from the filtrate obtained after filtering and removing zinc and then mixing it with the rubber;

[0018] Preferably, the rubber includes 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 eucommia gum, polyisoprene rubber, butadiene rubber, halogenated butyl rubber and EPDM rubber; preferably, the molecular weight of the rubber is 1,000 to 40 million, more preferably 5,000 to 30 million, and more preferably 10,000 to 8 million.

[0019] Preferably, the rubber comprises a diene rubber of the following formula II:

[0020]

[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 0 at the same time.

[0022] According to another aspect of the present application, a rubber composition is provided, which includes: an elastomer, a filler and a zinc-free vulcanization accelerator, wherein the zinc-free vulcanization accelerator is any one of the above-mentioned zinc-free vulcanization accelerators.

[0023] Further, the filler includes any one or more of a carbon-based filler, a silicon-based filler, a carbon-silicon dual-phase filler and clay;

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

[0025] Furthermore, the rubber composition includes 100 phr of an elastomer, 20 to 170 phr of a filler, and 10 to 50 phr of a zinc-free vulcanization aid;

[0026] Preferably, the rubber composition comprises 3 to 30 parts of other additives, and the other additives are selected from any one or more of resin, process oil, vulcanizing agent and silane coupling agent.

[0027] According to another aspect of the present application, a rubber product is provided, which is prepared from a rubber composition, wherein the rubber composition includes any one of the above-mentioned rubber compositions.

[0028] According to another aspect of the present application, a tire is provided, wherein the tire contains the above-mentioned rubber product.

[0029] By applying the technical solution of the present invention, the zinc-free vulcanization accelerator contains an active intermediate generated by pre-reaction of an antioxidant and a vulcanization system drug under the catalytic action of zinc oxide and stearic acid. The intermediate has the function of promoting vulcanization and plays the role of an early activation accelerator, so it can partially or completely replace the role of zinc oxide in ordinary formulas. By using the zinc-free vulcanization accelerator, zinc-free rubber products can be prepared, zinc-free emissions can be achieved, and it is environmentally friendly. Moreover, through the effect of the zinc-free vulcanization accelerator, the rubber composition can obtain the crosslinking density and hardness, tensile stress, hysteresis and other rubber properties close to those of zinc-containing rubber without zinc. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

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

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

[0033] The zinc-free vulcanization accelerator contains an active intermediate generated by pre-reaction of an antioxidant and a vulcanization system drug under the catalytic action of zinc oxide and stearic acid. The intermediate has the function of promoting vulcanization and plays the role of an early activation accelerator, so it can partially or completely replace the role of zinc oxide in ordinary formulas. By using the zinc-free vulcanization accelerator, zinc-free rubber products can be prepared, zinc-free emissions can be achieved, and it is environmentally friendly. Moreover, through the action of the zinc-free vulcanization accelerator, the rubber composition can obtain the crosslinking density and hardness, tensile stress, hysteresis and other rubber properties close to those of zinc-containing rubber without zinc.

[0034] Taking the phenylenediamine antioxidant and 2-thiobenzothiazole vulcanization system chemicals as an example, the reaction occurring in the pre-reaction is shown in the following reaction equation, and the generated active intermediate has the effect of promoting vulcanization.

[0035]

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

[0037] The ratio of zinc oxide, stearic acid, antioxidant, and vulcanization system medicine added in the above-mentioned pre-reaction can be set according to the ratio between 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 medicine 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 above-mentioned 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 better effect but is also more environmentally friendly. Its structural formula is as follows:

[0040]

[0041] In the formula, R 1 Selected from C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 The aromatic hydrocarbon 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 aliphatic rings separately or simultaneously, R 6 Selected from H, C1-C 18 Chain hydrocarbon groups, C3-C18 Alicyclic hydrocarbon or C6-C 18 an 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 has a value of 1, and at least one of y and z has a value of 1.

[0042] In some embodiments of the present application, the vulcanization system chemicals added in the pre-reaction include any one or more of a vulcanizing agent and an accelerator. In other embodiments of the present application, the vulcanization system chemicals added in the pre-reaction are any one or more of accelerators, and the vulcanizing agent is added during the preparation of the rubber product. Preferably, the vulcanizing agent includes any one or more of sulfur and sulfur carriers.

[0043] Preferably, the accelerator includes any one or more of sulfenamide accelerators and thiazole accelerators. Preferably, the accelerator includes 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 there is no special requirement for this application.

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

[0046] Since zinc oxide is insoluble 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 will remain in the filtrate, which can well separate the zinc oxide and avoid zinc residue.

[0047] In some typical embodiments of the present application, the zinc-free vulcanization accelerator also includes 50 to 150 phr of rubber, and the preparation method of the zinc-free vulcanization accelerator including rubber also includes the first mixing or the second mixing, wherein the first mixing includes: removing the solvent after mixing the filtrate obtained after filtering and removing zinc with the rubber; the second mixing includes: removing the solvent after mixing the filtrate obtained after filtering and removing zinc with the rubber. The zinc-free vulcanization accelerator containing rubber is a masterbatch type accelerator. Since it has been dispersed in the rubber, it has better effects in subsequent applications and is more conducive to the active intermediates generated by the pre-reaction of the antioxidant and the vulcanization system drugs for the crosslinking density and rubber enhancement. In particular, through the above-mentioned first mixing, the filtrate obtained after filtering and removing zinc can be evenly mixed with the rubber by a relatively simple method, such as stirring, and the rubber and other components therein are mixed more fully and evenly; in the above-mentioned second mixing, the filtration and zinc removal product after the solvent is removed 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. Among them, natural polymers include but are not limited to natural rubber, eucommia gum, guayule gum, etc. Synthetic polymers include but are not limited to monomers polymerized in solution (i.e., solution rubber), monomers polymerized in emulsion (i.e., emulsion rubber), and monomers polymerized in bulk. Solution rubber is a homopolymer or copolymer of ethylene, propylene, butene, pentene, hexene, heptene, diene with 4-7 carbon atoms or triene with 6-7 carbon atoms, or olefin monomers containing other atoms or functional groups, other atoms or functional groups include any one or more of silicon atoms, fluorine atoms, chlorine atoms, nitrogen atoms, oxygen atoms, sulfur atoms, ester groups, aminoester groups, and cyano groups, and also includes homopolymers and copolymers containing the above monomers, including but not limited to polybutadiene, polyisoprene, styrene-butadiene rubber, ethylene-propylene rubber, butyl rubber, nitrile rubber, chloroprene rubber, silicone rubber, fluororubber, polyurethane rubber, chlorosulfonated polyethylene rubber, acrylate rubber, etc.

[0049] The rubber in the zinc-free vulcanization aid of the present invention is preferably any one or more of natural rubber, styrene-butadiene rubber, isoprene rubber, natural eucommia gum, polyisoprene rubber, butadiene rubber, halogenated butyl rubber, and EPDM rubber.

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

[0051] In some embodiments of the present application, the rubber in the zinc-free vulcanization aid is a diene rubber having the following structure:

[0052]

[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 0 at the same time.

[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, in the diene rubber having the structure of Formula II, a, b, and c are 0, and d, e, and f are not 0; or a, b, and c are not 0, and d, e, and f are 0; or a, b, c, and d are 0, and e and f are not 0. The diene rubber having this structure has a higher crosslinking density.

[0056] Further, the sum of the number of alkenyl double bonds and aromatic groups on the side groups and side chains of the diene rubber shown in formula II accounts for 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 therebetween. It can be understood by those skilled in the art that the structure of formula II may contain only side groups or side chains, and may contain only alkenyl double bonds or aromatic groups on the side groups or side chains, and the number of alkenyl double bonds or aromatic groups on the side groups or side chains accounts for more than 15% of the sum of the number of all alkenyl double bonds and aromatic groups in the molecular structure of the diene rubber.

[0057] Preferably, the molecular weight of the structural rubber of formula II is 10,000 to 4,000,000.

[0058] Furthermore, the structural rubber of formula II accounts for more than 35% of the weight of the diene rubber, preferably, more than 60% of the weight of the diene rubber, for example, the weight content of the structural rubber of formula II in the diene rubber is 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%.

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

[0060] In the rubber composition, due to the use of the above-mentioned zinc-free vulcanization accelerator, the antioxidant and the vulcanization system drugs therein are pre-reacted under the catalytic action of zinc oxide and stearic acid to generate an active intermediate, and the intermediate has the effect of promoting vulcanization and plays the role of an early activation accelerator, so it can partially or completely replace the role of zinc oxide in the ordinary formula. The rubber composition of the present application uses the zinc-free vulcanization accelerator to prepare zinc-free rubber products, achieve zinc-free emissions, and be environmentally friendly. Moreover, through the action of the above-mentioned zinc-free vulcanization accelerator, it is possible to obtain crosslinking density and hardness, tensile stress, hysteresis and other rubber properties close to those of zinc-containing rubber compositions without 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 vulcanizing agent. There are no special requirements, and it will not be elaborated here.

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

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

[0064] The rubber composition of the present application may contain a vulcanizing agent, which may be added as one of the chemicals in the vulcanization system to the preliminary reaction for preparing the zinc-free vulcanizing agent, or may be contained in the rubber composition alone.

[0065] In some preferred embodiments of the present application, the rubber composition comprises 3 to 30 parts of other additives, and the other additives are selected from any one or more of resin, process oil, vulcanizing agent and silane coupling agent.

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

[0067] The rubber product is prepared from the zinc-free rubber composition, which not only achieves zinc-free emission, but also has rubber properties such as cross-linking density and hardness, tensile stress, hysteresis, etc. that are close to those of the zinc-containing rubber composition.

[0068] The method for preparing the rubber product by mixing the rubber composition can be selected from the prior art, and there is no special requirement for this application.

[0069] In some preferred embodiments of the present application, the vulcanization system drug added in the pre-reaction of the zinc-free vulcanization accelerator is an accelerator, and the zinc-free vulcanization accelerator is used to prepare the above-mentioned rubber product by the following method: (a) by kneading, the elastomer, filler, zinc-free vulcanization accelerator and other optional auxiliaries are mixed once or multiple times, and the mixing temperature reaches 125℃~200℃ to discharge the glue, as a masterbatch; (b) the masterbatch is thermomechanically kneaded once or multiple times, maintained at a kneading temperature of 125℃~180℃, and the glue is kept for 0~1200s to discharge, as a second masterbatch; if there are other remaining auxiliaries, fillers, antioxidants, all are added at this stage once or in batches; and (c) the second masterbatch is mixed with the vulcanization system in an internal mixer, the mixing temperature is ≤120℃, the glue is discharged, and the final mixing is obtained. In the above method, according to the specific mixing conditions adopted for the zinc-free vulcanization accelerator, the performance of the prepared rubber product can be further improved. Preferably, the final rubber mix prepared by the above process is vulcanized on a flat vulcanizer to obtain a vulcanized rubber.

[0070] According to another typical embodiment of the present application, a tire is provided, the tire containing the above-mentioned rubber product. Due to the use of the above-mentioned rubber product, the tire not only has good performance, but also can achieve zero or greatly reduced zinc emissions, 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 embodiments 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 Ikos New Materials Co., Ltd.;

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

[0075] Carbon black, N234, Shandong Zhongxiang Polymer Materials 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-butane, cis content 97%);

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

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

[0082] Zinc oxide, Dalian Zinc Oxide Factory;

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

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

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

[0086] Antioxidant A, synthesized by ourselves, has the structural formula

[0087] Antioxidant B, synthesized by ourselves, has the structural formula

[0088] Antioxidant C, synthesized by ourselves, has the structural formula

[0089] Antioxidant D, synthesized by ourselves, has the structural formula

[0090] Antioxidant E, synthesized by ourselves, has the structural formula

[0091] Antioxidant F, synthesized by ourselves, has the structural formula

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

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

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

[0095] Accelerator DPG, Shandong Shanxian Chemical Co., Ltd.;

[0096] Sulfur, Wudi Jinsheng Chemical Co., Ltd.

[0097] Example 1

[0098] 10 phr of stearic acid, 17.5 phr of zinc oxide, 10 phr of antioxidant 4020, and 10 phr of vulcanization accelerator TBBS were mixed in decane, pre-reacted at 160°C for 30 minutes, filtered to remove zinc oxide after returning to room temperature, and the filtrate was dried and mixed with 96.3 phr of SSBR and 30 phr of BR to obtain a zinc-free vulcanization accelerator;

[0099] The rubber compound was prepared according to the formula in Table 1. The specific method is as follows:

[0100] After adding SSBR and BR into the internal mixer and kneading, add carbon black N234 and the above-mentioned zinc-free vulcanizing agent, and continue kneading until the mixture is uniform. During the kneading process, the temperature is controlled at 150-160°C;

[0101] Add sulfur and knead, the temperature during kneading not exceeding 110°C;

[0102] The obtained rubber composition is vulcanized to obtain a vulcanized rubber, and the physical properties of the rubber are tested.

[0103] Comparative Example 1

[0104] The rubber compound was prepared according to the formula in Table 1. The specific method is as follows:

[0105] After adding SSBR and BR into the internal mixer and kneading, add carbon black N234, stearic acid, zinc oxide, antioxidant 4020, and accelerator TBBS and continue kneading until the mixture is uniform. During the kneading process, the temperature is controlled at 150-160℃.

[0106] Add sulfur and knead, the temperature during kneading not exceeding 110°C;

[0107] The obtained rubber composition is vulcanized to obtain a vulcanized rubber, and the physical properties of the rubber are tested.

[0108] Example 2

[0109] 10 phr of stearic acid, 17.5 phr of zinc oxide, 12.5 phr of antioxidant A, and 11.5 phr of vulcanization accelerator CZ were mixed in xylene, pre-reacted at 130°C for 40 minutes, filtered to remove zinc oxide after returning to room temperature, and the filtrate was dried and mixed with 100 phr of IR to obtain a zinc-free vulcanization accelerator;

[0110] The rubber compound was prepared according to the formula in Table 1. The specific method is as follows:

[0111] After adding IR to the internal mixer and kneading, add white carbon black, Si69, and the above-mentioned zinc-free vulcanizing agent, and continue kneading until the mixture is uniform. During the kneading process, the temperature is controlled at 150-160°C;

[0112] Add sulfur and DPG, knead, and the temperature during kneading does not exceed 120°C;

[0113] The obtained rubber composition is vulcanized to obtain a vulcanized rubber, and the physical properties of the rubber are tested.

[0114] Comparative Example 2

[0115] The rubber compound was prepared according to the formula in Table 1. The specific method is as follows:

[0116] After adding IR to the internal mixer and kneading, add white carbon black, Si69, stearic acid, zinc oxide, antioxidant A, and accelerator CZ, and continue kneading until the mixture is uniform. During the kneading period, the temperature is controlled at 150-160°C;

[0117] Add sulfur and DPG, knead, and the temperature during kneading does not exceed 120°C;

[0118] The obtained rubber composition is vulcanized to obtain a vulcanized rubber, and the physical properties of the rubber are tested.

[0119] Zero zinc blank samples Comparative Example 0-1 and Comparative Example 0-2 were set. The difference from Comparative Examples 1 and 2 was that zinc oxide was not added to Comparative Example 0-1 and Comparative Example 0-2.

[0120] Table 1 Rubber compound formula (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 content in rubber and its products by inductively coupled plasma atomic emission spectrometry”. The test results are shown in Table 2.

[0123] The vulcanization characteristics of the rubber compound were determined in accordance with GB / T16584-1996 Determination of vulcanization characteristics of rubber using a rotorless vulcanizer. The test results are shown in Table 3.

[0124] The physical properties of the rubber compound (tensile strength, elongation at break, 100% modulus of tensile stress, 300% modulus of tensile stress) were measured in accordance with GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber. The results are shown in Table 3.

[0125] The hardness of the rubber compound was measured in accordance with GB / T 531.1-2008 Test method for indentation hardness of vulcanized rubber or thermoplastic rubber Part 1: Shore hardness method (Shore hardness) and the test results are shown in Table 3.

[0126] The elastic modulus of the rubber at 20°C was determined according to GB / T9870.1-2006 Determination of dynamic properties of vulcanized rubber or thermoplastic rubber Part 1: General rules, and the tanδmax of the rubber was determined by a rotational rheometer. The test results are shown in Table 3.

[0127] Table 2

[0128]

[0129]

[0130] From the results in Table 2, it can be seen that the zinc content in the rubber composition containing the zinc-free vulcanization accelerator is equivalent to the zinc content in the zero-zinc blank sample without adding zinc oxide, and both are significantly lower than the zinc content in the ordinary zinc-containing formula.

[0131] In Table 3 and the subsequent physical property test result tables, for the convenience of comparison, the test data of each embodiment are based on the corresponding comparative example with the same composition except zinc oxide, and the index value is obtained. For example, in Table 1, the value of MH of Example 1 is the ratio of its measured value to the measured number of MH of Comparative Example 1*100; the larger the value, the higher the index.

[0132] Table 3 Physical property test results

[0133]

[0134] The results in Table 3 show that the rubbers prepared from the zinc-free rubber composition of the present invention (Examples 1 and 2) are close to those of the conventional zinc-containing rubbers (corresponding to Examples 1 and 2, respectively) in terms of crosslinking density, modulus, stress, hardness, mechanical properties, and hysteresis properties, and can be used in rubber products and tires.

[0135] The zinc-free vulcanization accelerators numbered #3 to #9 were prepared. The dosage of the specific components involved in the preparation process is shown in Table 4 below, and the process parameters are shown in Table 5 below. The preparation process is as follows: Stearic acid, zinc oxide, antioxidant, and vulcanization accelerator are mixed in a solvent, pre-reacted for a period of time, and the zinc oxide is removed by filtering after returning to room temperature. The filtrate is first desolventized and then mixed with rubber (#5 to #9), or mixed with rubber in liquid phase and then desolventized (#3 to #4) to obtain a zinc-free vulcanization accelerator. It was determined that the zinc content of zinc-free vulcanization accelerators #3 to #9 was 0.

[0136] The zinc-free vulcanization accelerators No. 10 to No. 14 were prepared with the same formula and preparation process as the zinc-free vulcanization accelerator No. 6 in Example, except for the pre-reaction parameter conditions listed in Table 5. It was determined that the zinc content of the zinc-free vulcanization accelerators No. 10 to No. 14 was 0.

[0137] Table 4

[0138]

[0139] Table 5

[0140]

[0141] Examples 3 to 9 were prepared in the same manner as Example 1, and Comparative Examples 3 to 9 were prepared in the same manner as Comparative Example 1 to prepare final rubber mixes and vulcanized rubbers, and their formulations are shown in Tables 6 and 7 below.

[0142] Table 6 Rubber compound formula (unit: phr)

[0143]

[0144] Table 7 Rubber compound formula (unit: phr)

[0145]

[0146] The formulations of Examples 10 to 14 are the same as those of Example 6 except for the zinc-free vulcanizing aid. The zinc-free vulcanizing aids of Examples 10 to 14 are zinc-free vulcanizing aids #10 to #14, respectively. The final rubber mix and the vulcanized rubber are prepared in the same manner as in Example 1.

[0147] Examples 3 to 14 and Comparative Examples 3 to 9 were tested using the same testing method as Example 1. The results are shown in Tables 8 and 9.

[0148] Table 8 Physical property test results

[0149]

[0150]

[0151] Table 9 Physical property test results

[0152]

[0153] Table 10 Physical property test results

[0154]

[0155] In Tables 8 and 9, the performance parameters of the rubber materials containing zinc-free vulcanization accelerators prepared by the present invention (Examples 3-9) and conventional zinc-containing rubber materials (corresponding to Examples 3-9, respectively) meet the requirements after vulcanization test, and can be used in the production of rubber products and tires. The vulcanized rubber materials of Examples 2, 5-14 above were extracted after aging, and the extracts were detected by ultra-high performance liquid chromatography-high resolution tandem mass spectrometry (UPLC-HRMS / MS), and no quinone compounds were detected, proving that the environmentally friendly para-aniline antioxidant AF used therein does not produce highly toxic quinone conversion products in the rubber residue, and is an environmentally friendly rubber additive.

[0156] In Table 10, when preparing zinc-free vulcanization aids, higher temperature and appropriate pre-reaction time are conducive to improving its performance, so that the rubber containing it has more excellent performance.

[0157] From the above description, it can be seen that the above embodiment of the present invention achieves the following technical effects: the above zinc-free vulcanization accelerator contains an active intermediate generated by pre-reaction of an antioxidant and a vulcanization system drug under the catalytic action of zinc oxide and stearic acid, and the intermediate has the effect of promoting vulcanization and plays the role of an early activation accelerator, so it can partially or completely replace the role of zinc oxide in ordinary formulas. By using the zinc-free vulcanization accelerator, zinc-free rubber products can be prepared, zinc-free emissions can be achieved, and it is environmentally friendly. Moreover, through the effect of the above zinc-free vulcanization accelerator, the rubber composition can obtain the cross-linking density and hardness, tensile stress, hysteresis and other rubber properties close to those of zinc-containing rubber without zinc.

[0158] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A zinc-free vulcanization aid, characterized in that: The zinc-free vulcanization accelerator is obtained by the following preparation method: zinc oxide, stearic acid, an antioxidant, and a vulcanization system chemical are pre-reacted in a solvent, and after the pre-reaction, zinc is removed by filtering and the solvent is removed in sequence to obtain the zinc-free vulcanization accelerator.

2. The zinc-free vulcanization aid according to claim 1, characterized in that: The reaction temperature of the pre-reaction is 100-190°C, and the reaction time is 1min-120min; Preferably, 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: 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 chemicals are added.

4. The zinc-free vulcanization aid according to any one of claims 1 to 3, characterized in that: The solvent is selected from any one or more of butanol, octanol, N-methylpyrrolidone, octane, nonane, decane, toluene and xylene; And / or, the antioxidant is a p-phenylenediamine antioxidant; And / or, the vulcanization system chemicals added in the pre-reaction include any one or more of vulcanizing agents and accelerators, the vulcanizing agent includes any one or more of sulfur and sulfur carriers, the accelerator includes any one or more of sulfonamide accelerators and thiazole accelerators, preferably, the accelerator includes any one or more of CZ, DCBS, MBTS, MBT and TBBS.

5. The zinc-free vulcanization aid according to claim 4, characterized in that: The antioxidant includes a compound having a structure shown in Formula I: In Formula I, R 1 Selected from C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 The aromatic hydrocarbon 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 aliphatic rings separately or simultaneously, R 6 Selected from H, C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 an 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 has a value of 1, and at least one of y and z has a value of 1.

6. The zinc-free vulcanization aid according to any one of claims 1 to 3, characterized in that: The zinc-free vulcanization accelerator also includes 50 to 150 phr of rubber. The preparation method of the zinc-free vulcanization accelerator including the rubber also includes a first mixing or a second mixing. The first mixing includes: removing the solvent from the filtrate obtained after filtering and removing zinc and mixing it with the rubber. The second mixing includes: removing the solvent from the filtrate obtained after filtering and removing zinc and mixing it with the rubber. Preferably, the rubber includes 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 eucommia gum, polyisoprene rubber, butadiene rubber, halogenated butyl rubber and EPDM rubber; preferably, the molecular weight of the rubber is 1,000 to 40 million, more preferably 5,000 to 30 million, and more preferably 10,000 to 8 million; Preferably, the rubber comprises a diene rubber having a structure shown in Formula II: 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 0 at the same time.

7. A rubber composition, characterized in that: include: An elastomer, a filler and a zinc-free vulcanization accelerator, wherein the zinc-free vulcanization accelerator is the zinc-free vulcanization accelerator according to any one of claims 1 to 6.

8. The rubber composition according to claim 7, characterized in that The filler includes any one or more of a carbon-based filler, a silicon-based filler, a carbon-silicon dual-phase filler and clay; Preferably, the specific surface area of ​​the filler is 10 to 500 m 2 / g, more preferably 30 to 300 m 2 / g, more preferably 50 to 300 m 2 / g.

9. The rubber composition according to claim 7, characterized in that: The rubber composition comprises 100 phr of elastomer, 20 to 170 phr of filler and 10 to 50 phr of zinc-free vulcanization aid; Preferably, the rubber composition comprises 3 to 30 parts of other additives, and the other additives are selected from any one or more of resin, process oil, vulcanizing agent and silane coupling agent.

10. A rubber product prepared from a rubber composition, characterized in that: The rubber composition includes the rubber composition according to any one of claims 7 to 9.

11. A tire, characterized in that: A rubber product comprising the rubber product according to claim 10.

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