Preparation method of polystyrene in-situ reinforced 1, 2-polybutadiene rubber, product and application

Abstract

The invention belongs to the field of rubber modification, and discloses a preparation method of polystyrene in-situ reinforced 1, 2-polybutadiene rubber, a product and application. The preparation method comprises the following steps: (1) in a protective atmosphere, carrying out polymerization reaction on a styrene solution in the presence of a first molybdenum catalyst to obtain a mixture containing polystyrene; and (2) mixing the mixture containing polystyrene with a second solvent, butadiene and a second molybdenum catalyst, and carrying out a second polymerization reaction in a protective atmosphere to obtain the in-situ blended polystyrene / 1, 2-polybutadiene rubber. The mechanical strength of the modified rubber is obviously improved, the modified rubber has lower Mooney viscosity, better processability and higher molecular weight, in addition, the content of a 1, 2 structure is high, the wet skid resistance, heat generation and rolling resistance of the rubber are improved, the rubber is suitable for tires and products, the application range of the 1, 2-polybutadiene rubber is further widened, and the 1, 2-polybutadiene rubber has good application prospects. And the method has extremely high application value.

Description

Technical Field

[0001] The invention belongs to the field of rubber modification, in particular to the field of in-situ enhanced modified 1,2-polybutadiene rubber, and specifically to a preparation method, product and application of polystyrene in-situ enhanced 1,2-polybutadiene rubber. Background Art

[0002] 1,2 Polybutadiene rubber (also known as high vinyl polybutadiene rubber, HVBR for short) is a non-polar rubber with a saturated alkane chain as the main chain and a large number of side vinyl groups (vinyl content greater than 65%) in the side chain. It has excellent properties of high anti-slip, low heat generation and low rolling resistance. If used in combination with other rubbers such as natural rubber, it can be used as a tread rubber for high-performance green tires. At the same time, the rich side vinyl groups increase the relaxation and internal friction of the HVBR molecular chain. Compared with natural rubber, styrene-butadiene rubber and butadiene rubber, the glass transition temperature of HVBR is closer to room temperature and the loss factor value is higher, so it can be used as a shock-absorbing material. However, compared with other synthetic rubbers, the physical and mechanical properties of HVBR are not outstanding. After HVBR is reinforced with fillers such as carbon black and white carbon black, the mechanical properties can be greatly improved, but the mechanical strength is still not as good as that of natural rubber and styrene-butadiene rubber reinforced with fillers. Therefore, if the mechanical strength of HVBR can be further improved, its application in tires and products can be expanded.

[0003] In addition to reinforcing rubber with fillers, it can also be blended with plastics to improve mechanical properties. For example, Wuhu Xinhai Rubber and Plastic Products Co., Ltd. invented a NBR / PVC blended rubber and plastic material and its preparation method (CN102993500A, application number CN201210399734.2). The NBR / PVC blended rubber and plastic material has the ozone resistance of PVC and the oil resistance and cross-linkability of NBR, and improves the tensile strength, tensile stress, tear resistance and other mechanical properties of the original material. At present, there is no research on improving the mechanical properties of HVBR by blending rubber and plastics. In addition, HVBR contains rich side vinyl, high Mooney viscosity, poor processing performance, and difficulty in physical blending with plastics. It is difficult to achieve the desired effect due to poor dispersibility.

[0004] Qingdao University of Science and Technology invented a HVBR (CN105777964A, application number: CN201610147275.7) blended in situ with industrialized ethylene vinyl acetate rubber to prepare a material blended at the molecular level of two-phase polymers, which significantly improves the compatibility of the two phases and improves the damping performance of the polymer blend. However, the inventors of the present invention have found that industrially produced rubber or plastic generally contains residual catalysts or other impurities, which will poison molybdenum catalysts, affect polymerization activity, and limit industrial production.

[0005] Sinopec has invented a method for preparing high-vinyl styrene-butadiene copolymers using a molybdenum-based catalytic system (CN106699967A, application number CN201510780995.2). However, the molybdenum-based styrene-butadiene rubber obtained by this method has a low molecular weight, a wide molecular weight distribution, and high compression heat generation, and can only be used to prepare high-performance tire tread rubber, high-impact polystyrene, ABS and other high-performance plastics modifiers.

[0006] In summary, the physical and mechanical properties of conventional 1,2-polybutadiene rubber need to be further improved. However, either the Mooney viscosity of 1,2-polybutadiene rubber is large, the processing performance itself is poor, the physical blending processing with plastics is difficult, and the poor dispersion makes it difficult to achieve the desired effect; or, the in-situ blending polymerization activity is low, and it is difficult to use an efficient method to in-situ enhance rubber or plastic with 1,2-polybutadiene rubber, which is not suitable for industrial production; or, the molecular weight of the obtained rubber is low, or the molecular weight distribution is wide, and it cannot be used in tires and products, and can only be used as a modification aid. Summary of the invention

[0007] In order to overcome the above-mentioned defects in the prior art, the inventor of the present invention unexpectedly discovered through research that the preparation method of polystyrene in-situ reinforced 1,2-polybutadiene rubber (HVBR) of the present invention is adopted, and a polymerization system is obtained after synthesizing polystyrene by a molybdenum-based catalyst, and the polymerization system is directly blended with butadiene monomer, and a molybdenum-based catalyst is added to prepare HVBR blended in situ with polystyrene, so that polystyrene in-situ reinforced 1,2-polybutadiene rubber (HVBR) can be obtained. The mechanical strength of the polystyrene in-situ reinforced 1,2-polybutadiene rubber is significantly improved, and it has a lower Mooney viscosity and better processing performance. Not only that, it has a higher molecular weight under the condition of having a lower Mooney viscosity. In addition, the polystyrene in-situ reinforced 1,2-polybutadiene rubber of the present invention has a high content of 1,2 structure, and the rubber has improved anti-slip properties, heat generation and rolling resistance. The rubber is suitable for tires and products, further broadening the application range of 1,2-polybutadiene rubber, and has extremely high application value.

[0008] The first aspect of the present invention is to provide a method for preparing polystyrene in-situ reinforced 1,2-polybutadiene rubber, comprising:

[0009] (1) subjecting a styrene solution to a first polymerization reaction in the presence of a first molybdenum-based catalyst under a protective atmosphere to obtain a mixture containing polystyrene;

[0010] (2) mixing the mixture containing polystyrene obtained in step (1) with a second solvent, butadiene and a second molybdenum-based catalyst, and performing a second polymerization reaction under a protective atmosphere to obtain an in-situ blended polystyrene / 1,2-polybutadiene rubber;

[0011] The first molybdenum-based catalyst and the second molybdenum-based catalyst each include a molybdenum compound, an alkyl aluminum, and a phosphoric acid ester.

[0012] The invention prepares HVBR by using molybdenum catalysts, firstly prepares polystyrene by using molybdenum catalysts, then adds butadiene and molybdenum catalysts into the polymerization system to prepare styrene in-situ enhanced HVBR.

[0013] According to the present invention, the molar ratio of styrene, molybdenum compound, alkyl aluminum and phosphate ester can be selected within a wide range. In a preferred embodiment of the present invention, in step (1): the molar ratio of styrene, molybdenum compound, alkyl aluminum and phosphate ester is (100-6000):1:(5-30):(1-5); preferably (1500-6000):1:(8-20):(1-3).

[0014] According to the present invention, preferably, the molar ratio of styrene to the molybdenum compound is (1500-6000):1, for example, 1500, 2000, 2500, 3000, 4000, 5000, 6000 and the ratio of any two values ​​or any interval between any two values ​​to 1.

[0015] According to the present invention, preferably, the molar ratio of the molybdenum compound to the alkyl aluminum is 1:(8-20), for example, the ratio of 1 to 8, 10, 14, 16, 18, 20 and any two values ​​or any interval between any two values.

[0016] According to the present invention, preferably, the molar ratio of the molybdenum compound to the phosphate is 1:(1-3), for example, the ratio of 1 to 1, 1.5, 2, 2.5, 3 and any two values ​​or any interval between any two values.

[0017] According to the present invention, the concentration of the styrene solution can be selected in a wide range. In a preferred embodiment of the present invention, the concentration of the styrene solution is 0.96-1.92 mol / L (i.e., M), such as 0.96 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 1.92 mol / L, and any two values ​​or any interval between any two values.

[0018] According to the present invention, the conditions for the first polymerization reaction in step (1) can be selected within a wide range. In a preferred embodiment of the present invention, the conditions for the first polymerization reaction in step (1) include: a temperature of 60-90° C., and / or a time of 8-12 h.

[0019] In a preferred embodiment of the present invention, the protective atmosphere is nitrogen and / or an inert gas.

[0020] According to the present invention, the solvent used for the styrene solution can be selected from a wide range. In a preferred embodiment of the present invention, the solvent used for the styrene solution is at least one of toluene, n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octane.

[0021] According to the present invention, the amount of the mixture containing polystyrene can be selected within a wide range. In a preferred embodiment of the present invention, based on the mass of polystyrene, the amount of the mixture containing polystyrene is such that the mass ratio of polystyrene to butadiene is (0.5-20):100, preferably (2-15):100, for example, 2, 5, 8, 10, 13, 15, and the ratio of any two values ​​or any interval between any two values ​​to 100.

[0022] According to the present invention, in step (2): the molar ratio of butadiene, molybdenum compound, alkyl aluminum and phosphate ester can be selected within a wide range. In a preferred embodiment of the present invention, the molar ratio of butadiene, molybdenum compound, alkyl aluminum and phosphate ester is (500-8000):1:(5-30):(1-5), preferably (2000-6000):1:(10-24):(2-4).

[0023] According to the present invention, preferably, the molar ratio of butadiene to the molybdenum compound is (2000-6000):1, for example, 2000, 2500, 3000, 4000, 5000, 6000 and the ratio of any two values ​​or any interval between any two values ​​to 1.

[0024] According to the present invention, preferably, the molar ratio of the molybdenum compound to the alkyl aluminum in step (2) is 1:(10-24), for example, the ratio of 1 to 10, 14, 16, 18, 20, 22, 24 and any two values ​​or any interval between any two values.

[0025] According to the present invention, preferably, the molar ratio of the molybdenum compound to the phosphate in step (2) is 1:(2-4), for example, the ratio of 1 to 2, 2.5, 3, 3.5, 4, and any two values ​​or any interval between any two values.

[0026] According to the present invention, the amount of the second solvent can be selected within a wide range. In a preferred embodiment of the present invention, the amount of the second solvent is such that the concentration of butadiene in the second solvent is 1-5 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, and any two values ​​or any interval between any two values.

[0027] According to the present invention, the second solvent can be selected from a wide range. In a preferred embodiment of the present invention, the second solvent is selected from at least one of toluene, n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octane.

[0028] According to the present invention, the conditions for the second polymerization reaction in step (2) can be selected within a wide range. In a preferred embodiment of the present invention, the conditions for the second polymerization reaction in step (2) include:

[0029] The temperature is 40° C.-80° C., and / or the reaction time is 4-12 h, and / or the mixing method is stirring, preferably with a stirring speed of 20-600 rpm.

[0030] In a preferred embodiment of the present invention, the protective atmosphere is nitrogen and / or an inert gas.

[0031] According to the present invention, the molybdenum compound can be selected from a wide range. In a preferred embodiment of the present invention, the molybdenum compound is selected from at least one of molybdenum pentachloride, molybdenum tetrachloride and molybdenum dichloride.

[0032] According to the present invention, the alkyl aluminum can be selected from a wide range. In a preferred embodiment of the present invention, the alkyl aluminum is selected from at least one of trimethyl aluminum, tripropyl aluminum, tributyl aluminum, diisobutyl aluminum hydride, and meta-cresol aluminum.

[0033] According to the present invention, the phosphate ester can be selected in a wide range. In a preferred embodiment of the present invention, the phosphate ester is selected from at least one of triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, di(2-ethylhexyl) phosphate, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, triisopropylphenyl phosphate, and triisooctyl phosphate.

[0034] In a preferred embodiment of the present invention, the preparation method further comprises vulcanizing the in-situ blended polystyrene / 1,2-polybutadiene rubber obtained in step (2) with an additive to obtain polystyrene in-situ reinforced 1,2-polybutadiene rubber.

[0035] According to the present invention, the auxiliary agent for vulcanization can be a conventional auxiliary agent in the art. In a preferred embodiment of the present invention, in parts by mass, relative to 100 parts of in-situ blended polystyrene / 1,2-polybutadiene rubber, the auxiliary agent for vulcanization includes: 20-60 parts of carbon black, 1-3 parts of ZnO, 0.5-1.5 parts of stearic acid, 0.4-0.6 parts of accelerator, 0.4-0.8 parts of antioxidant, and 0.5-2 parts of vulcanizing agent.

[0036] According to the present invention, the accelerator, antioxidant and vulcanizer are all commonly used additives in rubber, including but not limited to the types or models of additives specifically used in the present invention.

[0037] In a preferred embodiment of the present invention, the mixing step before vulcanization comprises:

[0038] The in-situ blended polystyrene / 1,2-polybutadiene rubber and the additives except the vulcanizing agent are first mixed and kneaded, and then the vulcanizing agent is added and the kneading is continued.

[0039] According to the present invention, the vulcanization conditions can be selected within a wide range. In a preferred embodiment of the present invention, the vulcanization conditions include: temperature 120°C-160°C, and / or time 1-60 min, and / or pressure 1-10 MPa.

[0040] In order to facilitate the understanding of the present invention, a preferred embodiment of the present invention is used for description below:

[0041] The method for preparing styrene in-situ reinforced 1,2-polybutadiene rubber of the present invention comprises the following steps:

[0042] (1) Under a nitrogen atmosphere, a certain concentration of styrene solution and a molybdenum-based catalyst are added to a reactor, heated to 60-90° C., and reacted for 8-12 hours.

[0043] (2) dissolving the polystyrene solution obtained in step (1) to a certain concentration preferably with a solvent, adding the butadiene solution to a polystyrene solution reactor under a nitrogen atmosphere, then adding a molybdenum-based catalyst to the reactor, heating to 40° C.-80° C., and then stirring the reaction for 4-12 hours at a stirring speed of 20-600 rpm;

[0044] (3) The prepared high vinyl polybutadiene rubber in situ blended with styrene is processed and vulcanized according to a certain formula to obtain a PS plastic / polybutadiene in situ intercalated plastic / rubber composite material (in situ-Plastic / HVBR).

[0045] Based on the above technical solution, preferably, the styrene concentration in step (1) is 0.96-1.92M, and the solvent used is one or more of toluene, n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octane.

[0046] Based on the above technical solution, preferably, the solvent used in step (2) is one or two of n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octane.

[0047] On the basis of the above technical solution, preferably, in the step (2), the mass fraction of polystyrene in butadiene is 0.5%-20%, and the solvent of the butadiene solution is selected from one or more of toluene, n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octane.

[0048] On the basis of the above technical solution, preferably, the components of the molybdenum-based catalyst used in step (1) and step (2) are a molybdenum compound, an alkyl aluminum and a phosphate ester, wherein the molybdenum compound is molybdenum pentachloride, molybdenum tetrachloride or molybdenum dichloride; the alkyl aluminum is one or more of trimethyl aluminum, tripropyl aluminum, tributyl aluminum, diisobutyl aluminum hydride and meta-cresol aluminum; and the phosphate ester is one or more of triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, di(2-ethylhexyl) phosphate, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, triisopropylphenyl phosphate and triisooctyl phosphate.

[0049] On the basis of the above technical solution, preferably, the molar ratio of butadiene, molybdenum compound, alkyl aluminum and phosphate is 5000:1:10-24:2-4.

[0050] On the basis of the above technical solution, more preferably, the formula in step (3) is: in situ-Plastic / HVBR 100phr; carbon black 45phr, ZnO 1.65phr; stearic acid 1.1phr; accelerator NS 0.55phr; antioxidant RD 0.55phr; sulfur 1phr.

[0051] On the basis of the above technical solution, more preferably, the processing technology in the step (3) is: the above formula (except sulfur) is kneaded at 60r / min for 15min at 80°C using a torque rheometer, sulfur is added on an open mill for 4 times, and then the sheet is unloaded, and the thickness of the sheet is 2mm.

[0052] On the basis of the above technical solution, more preferably, the vulcanization process in step (3) is: temperature 120°C-160°C, time 1-60min, pressure 1-10MPa.

[0053] The second aspect of the present invention is to provide a polystyrene in-situ reinforced 1,2-polybutadiene rubber, wherein the polystyrene in-situ reinforced 1,2-polybutadiene rubber is prepared by the preparation method described in the first aspect.

[0054] In a preferred embodiment of the present invention, the mass content of the 1,2 structure of the polystyrene in-situ reinforced 1,2-polybutadiene rubber is 80%-85%, and / or the Mooney viscosity is 60-75.

[0055] In the present invention, "and / or" means that either one of the conditions on both sides of "and / or" can be adopted, or both conditions can exist at the same time.

[0056] The third aspect of the present invention is to provide a use of the polystyrene in-situ reinforced 1,2-polybutadiene rubber described in the second aspect in a tire and / or tire product.

[0057] It can be known from the above records that the preparation method of polystyrene in-situ reinforced 1,2-polybutadiene rubber (HVBR) of the present invention is adopted, and a polymerization system is obtained after synthesizing polystyrene by a molybdenum catalyst, and the polymerization system is directly blended with butadiene monomer, and a molybdenum catalyst is added to prepare HVBR of polystyrene in-situ blending, so that polystyrene in-situ reinforced 1,2-polybutadiene rubber (HVBR) can be obtained. Because the same molybdenum catalyst is used, the post-processing is simple, the process is simple, and the conventional plastic reinforcement of different catalytic systems is avoided with residual catalysts or other impurities, which will poison the molybdenum catalyst, affect the polymerization activity, and limit industrial production; and the in-situ blended polystyrene of the present invention has good dispersibility in HVBR, and the Mooney viscosity of the obtained product is reduced and has a higher molecular weight, so that the processing performance is improved, and the mechanical strength, not only that, the polystyrene in-situ reinforced 1,2-polybutadiene rubber of the present invention has improved anti-slip, heat generation, rolling resistance and other properties.

[0058] The beneficial effects achieved by the present invention are:

[0059] 1) Polystyrene is prepared by using a molybdenum catalyst. After the polymerization is completed, there are few impurities in the system that poison the molybdenum catalyst, which does not affect the polymerization of the next step of molybdenum polybutadiene. There are few post-processing processes, the process is simple, and it is conducive to industrial scale-up.

[0060] 2) During the polymerization of butadiene, the mass fraction of polystyrene is adjustable, which can control the synthesis of high-vinyl polybutadiene rubber with high molecular weight and high 1,2-structure content without affecting the excellent properties of HVBR itself, such as high anti-skid performance, low heat generation and low rolling resistance.

[0061] 3) Polystyrene is reinforced with 1,2-polybutadiene by an in-situ blending method, which avoids the shortcomings of poor dispersibility and processing performance of polystyrene in HVBR. The mechanical strength of the obtained product is significantly improved, the Mooney viscosity is reduced, the processing performance is improved, and the anti-slip, heat generation and rolling resistance properties are all improved.

[0062] In summary, on the one hand, the preparation method of the present invention has high polymerization activity and monomer conversion rate, and is suitable for industrial production; on the other hand, the mechanical strength of the polystyrene in-situ reinforced 1,2-polybutadiene rubber of the present invention is significantly improved, not only that, the polystyrene in-situ reinforced 1,2-polybutadiene rubber has a lower Mooney viscosity and better processing performance, and more unexpectedly, it has a higher molecular weight while having a lower Mooney viscosity, not only that, the anti-slip, heat generation and rolling resistance of the polystyrene in-situ reinforced 1,2-polybutadiene rubber of the present invention are slightly improved. In view of the comprehensive performance of the polystyrene in-situ reinforced 1,2-polybutadiene rubber of the present invention, the rubber is suitable for tires and products, further broadening the application range of 1,2-polybutadiene rubber, and has extremely high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is the infrared spectra of Comparative Example 1 and Examples 1-2;

[0064] Depend on Figure 1 It can be seen that at 698cm -1 The absorption peak is the polystyrene absorption peak at 908cm -1 The strong absorption peak of 1,2-polybutadiene structure appears, indicating that there is more 1,2-polybutadiene in the polymer, at 968cm -1 The absorption peak of 1,4-polybutadiene structure appears, which indicates that the polybutadiene chain segments in the polymerization product are mainly 1,2-polybutadiene, and the product is a high-vinyl polymerization product.

[0065] Figure 2 The scanning electron microscope images of comparative examples 1-3 and embodiment 1. The scale in the image is 10 μm, and the white circles are the etched polystyrene;

[0066] Figure 3 It is a dynamic mechanical performance diagram of comparative examples 1-3 and embodiment 1. DETAILED DESCRIPTION

[0067] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0068] The specific implementation of the present invention is further described below in conjunction with the examples and drawings.

[0069] The experimental methods described in the following examples are conventional methods unless otherwise specified; if no specific techniques or conditions are specified in the examples, they are carried out according to the techniques or conditions described in the literature in the field or according to the product instructions; the reagents and materials are all analytically pure reagents and can be obtained from commercial channels unless otherwise specified.

[0070] The unit of dosage, phr, is the number of parts added per 100 parts of rubber by mass. In the following examples, as an example, M in a styrene toluene solution having a concentration of 1.5 M refers to mol / L.

[0071] The test methods used in this embodiment and comparative example are described as follows:

[0072] 1. The infrared spectra (FTIR) were measured using a VERTEX70 (Bruker, Germany) infrared spectrometer in total reflection mode.

[0073] 2. Scanning electron microscopy (SEM) tests were performed on a JMS-6700F (JEOL, Japan) scanning microscope equipped with an energy dispersive X-ray (EDX ISIS 300, Oxford, UK) microanalysis system. Prior to SEM testing, the samples were freeze-fractured in liquid nitrogen and then extracted with toluene in a Soxhlet extractor for 24 h.

[0074] 3. Tensile and tear tests were performed on a GT-AT-7000M (Taiwan Gotech, China) electronic tensile testing machine at a speed of 500 mm / min.

[0075] 4. Dynamic mechanical properties were performed by DMA Q800 (TA, United States) in the temperature scanning mode from −60 °C to 80 °C at a rate of 3 °C / min, with a vibration amplitude of 10 μm and a frequency of 1 Hz.

[0076] 5. The detection method of monomer conversion rate is: weighing method;

[0077] 6. The detection method of number average molecular weight is: GPC; the detection method of Mw / Mn is: mass spectrometry;

[0078] 7. The test method for Mooney viscosity is: GB / T 1232.1-2016;

[0079] 8. The detection method of 1,2-butadiene structure content is: infrared spectroscopy;

[0080] 9. Damping performance test method: DMA Q800 (TA, United States) was used in the temperature scanning mode from -60°C to 80°C at a rate of 3°C / min, with a vibration amplitude of 10 μm and a frequency of 1 Hz.

[0081] Preparation Example 1 (Preparation of molybdenum-based polystyrene)

[0082] A 1.5M styrene toluene solution was added into the reactor and heated to 70°C. Then a molybdenum-based catalyst was injected into the reactor. The molar ratio of styrene, molybdenum pentachloride, aluminum metacresol and triethyl phosphate was 5000:1:10:2. The polymerization reaction was carried out for 9 hours to obtain molybdenum-based polystyrene (PS), which was then cooled for later use.

[0083] Preparation Example 2 (Preparation of molybdenum-based polystyrene)

[0084] A 1.0 M styrene toluene solution was added into the reactor and heated to 80°C. Then a molybdenum-based catalyst was injected into the reactor. The molar ratio of styrene, molybdenum pentachloride, aluminum metacresol and triethyl phosphate was 4000:1:12:1.5. The polymerization reaction was carried out for 8 hours to obtain molybdenum-based polystyrene (PS), which was then cooled for later use.

[0085] Preparation Example 3 (Preparation of molybdenum-based polystyrene)

[0086] A 1.2 M styrene toluene solution was added into the reactor and heated to 75°C. Then a molybdenum-based catalyst was injected into the reactor. The molar ratio of styrene, molybdenum pentachloride, aluminum metacresol and triethyl phosphate was 6000:1:15:1.2. The polymerization reaction was carried out for 8.5 hours to obtain molybdenum-based polystyrene (PS), which was then cooled for later use.

[0087] Example 1

[0088] Under nitrogen atmosphere, a certain amount of the polystyrene toluene solution obtained in Preparation Example 1 was added to a 2.6M butadiene n-hexane solution, added to a reactor and heated to 60°C, wherein the mass of the polystyrene was 5% of the mass of the butadiene. Then, a molybdenum-based catalyst was injected into the reactor, and the molar ratio of butadiene, molybdenum pentachloride, aluminum metacresol and tributyl phosphate was 5000:1:10:2. After reacting for 6 hours, ethanol was added to terminate the polymerization, and the obtained rubber-plastic composite material was poured into boiling water to obtain a precipitate, which was vacuum dried at 80°C to constant weight to obtain in-situ blended polystyrene / 1,2-polybutadiene rubber (HVBR / PS5).

[0089] The obtained in-situ blended 100phr in-situ blended polystyrene / 1,2-polybutadiene rubber was mixed with 45phr carbon black, 1.65phr ZnO, 1.1phr stearic acid, 0.55phr accelerator NS, 0.55phr antioxidant RD in a mixing mill, mixed at 80°C and 60r / min for 15min, then 1phr sulfur was added to the mixing mill for 4 times, and then the sheet was cut to a thickness of 2mm. The above-mentioned mixed rubber was vulcanized at 150°C for 30min and a pressure of 5MPa to obtain vulcanized polystyrene / 1,2-polybutadiene rubber (in situ-HVBR / PS5).

[0090] Example 2

[0091] The preparation method is the same as that in Example 1, except that the solvent of the butadiene solution is selected from n-pentane, the mass of polystyrene is 8% of the mass of butadiene, the molybdenum compound is molybdenum tetrachloride, the alkyl aluminum and the phosphate are tripropyl aluminum and di(2-ethylhexyl) phosphate, respectively, and the molar ratio of butadiene, the molybdenum compound, the alkyl aluminum and the phosphate is 5000:1:14:2. According to the same mixing formula and vulcanization process as in Example 1, an HVBR / PS rubber-plastic composite material (HVBR / PS8) with a polystyrene mass fraction of 8% is prepared, and it is named in situ-HVBR / PS8.

[0092] Example 3

[0093] The same method as in Example 1 was used for preparation, except that the solvent of the butadiene solution was selected from n-pentane, the mass of polystyrene was 10% of the mass of butadiene, the molybdenum compound was molybdenum tetrachloride, the alkyl aluminum and the phosphate were tripropyl aluminum and di(2-ethylhexyl) phosphate, respectively, and the molar ratio of butadiene, the molybdenum compound, the alkyl aluminum and the phosphate was 5000:1:14:2. According to the same mixing formula and vulcanization process as in Example 1, an HVBR / PS rubber-plastic composite material (HVBR / PS10) with a polystyrene mass fraction of 10% was prepared, and was named in situ-HVBR / PS10.

[0094] Example 4

[0095] Polystyrene in-situ reinforced 1,2-polybutadiene rubber (after vulcanization) was prepared according to the method of Example 2, except that the polystyrene toluene solution in Preparation Example 2 was used instead of the polystyrene toluene solution in Preparation Example 1.

[0096] Example 5

[0097] Polystyrene in-situ reinforced 1,2-polybutadiene rubber (after vulcanization) was prepared according to the method of Example 2, except that the polystyrene toluene solution in Preparation Example 3 was used instead of the polystyrene toluene solution in Preparation Example 1.

[0098] Example 6

[0099] The polystyrene in-situ reinforced 1,2-polybutadiene rubber (after vulcanization) was prepared according to the method of Example 3, except that the polystyrene toluene solution in Preparation Example 3 was used instead of the polystyrene toluene solution in Preparation Example 1.

[0100] Example 7

[0101] The polystyrene in-situ reinforced 1,2-polybutadiene rubber (after vulcanization) was prepared according to the method of Example 3, except that the amount of the polystyrene mixture was such that the mass ratio of polystyrene to butadiene was 18:100.

[0102] Example 8

[0103] Polystyrene in-situ reinforced 1,2-polybutadiene rubber (after vulcanization) was prepared according to the method of Example 3, except that the amount of the polystyrene mixture was such that the mass ratio of polystyrene to butadiene was 20:100, and the molar ratio of butadiene, molybdenum compound, alkyl aluminum and phosphate was 7000:1:8:3.

[0104] Example 9

[0105] Polystyrene in-situ reinforced 1,2-polybutadiene rubber (after vulcanization) was prepared according to the method of Example 3, except that the amount of the polystyrene mixture was such that the mass ratio of polystyrene to butadiene was 18:100, and the molar ratio of butadiene, molybdenum compound, alkyl aluminum and phosphate was 7000:1:8:1.5.

[0106] Comparative Example 1 (HVBR without styrene)

[0107] The same polymerization method as in Example 1 was used to polymerize butadiene without adding polystyrene to prepare pure HVBR01. The obtained pure HVBR was subjected to the same mixing formula and vulcanization process as in Example 1 to prepare HVBR02 vulcanizate without adding polystyrene.

[0108] Comparative Example 2 (HVBR / PS rubber-plastic composite material prepared by physical blending)

[0109] Butadiene was polymerized by the same polymerization method as in Example 1 but without adding polystyrene to prepare pure HVBR, and then the obtained polymer was physically blended with 5% polystyrene. The obtained physically mixed 100phr Ph-HVBR / PS rubber-plastic composite material was subjected to the same mixing formula and vulcanization process as in Example 1 on a double-roll mill to prepare a physically blended HVBR / PS rubber-plastic composite material with a polystyrene mass fraction of 5%, named Ph-HVBR / PS5.

[0110] Comparative Example 3 (HVBR / PS rubber-plastic composite material prepared by solution co-precipitation method)

[0111] Butadiene was polymerized by the same polymerization method as in Example 1 but without adding polystyrene to prepare pure HVBR. After HVBR was dissolved, 5% by mass of polystyrene obtained in Preparation Example 1 was added, the product was poured into boiling water for precipitation, and dried to constant weight at 80°C in a vacuum drying oven to obtain solution co-precipitation method HVBR / PS5, which was then used in the same mixing formula and vulcanization process as in Example 1 to obtain a solution co-precipitated HVBR / PS rubber-plastic composite material with a polystyrene mass fraction of 5%, named So-HVBR / PS5.

[0112] Polymerization activity and performance testing

[0113] From Table 1 we can see that:

[0114] The monomer conversion rate is an important indicator for evaluating the catalytic effect of the catalytic system. A high conversion rate is conducive to improving the monomer utilization rate and reducing the catalyst dosage and raw material consumption. As can be seen from Table 1, the addition of molybdenum polystyrene does not affect the polymerization activity. Compared with Comparative Example 1, it can be seen that when the amount of molybdenum polystyrene added is 10%, the monomer conversion rate is only reduced by 1%.

[0115] From Comparative Example 1, it can be seen that the catalyst activity in the molybdenum-based HVBR is high, it is not easy to chain transfer, the molecular weight is large, the Mooney viscosity is large, and the processing performance is poor; after the addition of polystyrene, although the number average molecular weight of HVBR is significantly reduced, it is still above 300,000, and the molecular weight distribution becomes wider. Therefore, the addition of polystyrene can reduce the Mooney viscosity and improve the processing performance without affecting the performance.

[0116] Different conditions of conventional preparation methods will affect the 1,2-structure content. Low 1,2-structure content may affect the performance of the product, while high 1,2-structure content means good wet skid resistance and rolling resistance of the product. After adding polystyrene using the preparation method of the present invention, the 1,2-structure content of HVBR is above 80%, which also shows that this in-situ blending method will not affect the configuration of the active center of the molybdenum-based HVBR, and the obtained product still belongs to high vinyl polybutadiene.

[0117] Table 1 Effect of polystyrene on the activity and structure of polybutadiene

[0118]

[0119]

[0120] After the sample was vulcanized, the liquid nitrogen-fractured specimens were extracted with toluene in a Soxhlet extractor for 24 hours to etch out the styrene in the system. SEM scanning was then performed to analyze the effects of different dispersion methods on the dispersion of styrene in HVBR ( Figure 2 ), the white circles in the figure mark the holes left after the etching of styrene. The hole size in Comparative Example 2 (Ph-HVBR / PS5) is the largest (10μm), indicating that the dispersion of styrene in HVBR in the physical blending method is relatively poor, while the hole sizes in Comparative Example 3 (So-HVBR / PS5) and Example 1 (Insitu-HVBR / PS5) are also relatively small, and compared with So-HVBR / PS5, the surface of the material in Example 1 is smoother and the dispersion of styrene is better.

[0121] Table 2 Mechanical properties of samples prepared under different conditions

[0122] PS (wt% Bd) Tensile strength(MPa) Tear strength (MPa) Comparative Example 1 0 10 28 Comparative Example 2 5 12 30 Comparative Example 3 5 14 31 Example 1 5 16 36 Example 2 8 18 34 Example 3 10 17 32 Example 4 8 18 33 Example 5 8 18.5 33 Example 6 10 17.5 34 Example 7 18 16 33 Example 8 20 15 32 Example 9 20 15.5 32

[0123] The effects of different blending methods on the tensile strength and tear strength of the material (after vulcanization) are shown in Table 2. Compared with Comparative Examples 1-3, the tensile strength and tear strength of the rubber material in the examples obtained by the in-situ blending method of the present invention are significantly improved. For example, the tensile strength of Example 1 of the in-situ blending method is increased by 1.5 times, and the tear strength is increased by 1.2 times. The mechanical properties of the HVBR not reinforced with styrene in Comparative Example 1 are the worst, while the mechanical properties of the HVBR with styrene added in Comparative Examples 2 and 3 are improved compared with the comparative examples, but are significantly lower than the products of the examples of the present invention.

[0124] Table 3 Damping performance of comparative examples 1-3 and embodiment 1

[0125]

[0126] Depend on Figure 3 It can be seen from Table 2 that the effective damping temperature range (tanδ>0.3) of the mechanically blended comparative example 2 (Ph-HVBR / PS5) is 32.73°C, which is lower than 35.62°C of the comparative example 1 (HVBR) without styrene addition. The damping temperature range of 1 (Insitu-HVBR / PS5) in Example 1 is 32.37°C, which is the largest decrease, indicating that the mechanical blending method makes the PS most unevenly dispersed in the HVBR, while the in-situ blending method makes the PS more evenly dispersed in the HVBR.

[0127] The In situ-HVBR / PS5 of Example 1 of the in-situ blending method has the highest tan δ value at 0°C, indicating that the wet skid resistance is improved, while the tan δ at 60 and 80°C is the lowest, indicating that the rolling resistance and heat generation are reduced.

[0128] In summary, the present invention can reduce the Mooney viscosity of HVBR polymers and improve processing performance. The Mooney viscosity of the polymer obtained by the present invention is reduced to 60-75, so that the processing performance is better, while the molecular weight can still be maintained at about 300,000, and the tensile strength is above 16MPa, the tear strength is above 32MPa, and the mechanical properties are significantly improved. In addition, the 1,2-structure content in the polymer of the present invention is above 80wt%, and the product is a high vinyl polymerization product.

[0129] The rubber product is used in tires, and the good anti-skid performance of the tire can reduce the chance of the tire slipping on wet and slippery ground. The good heat generation performance means that the tire generates less heat during the friction of the movement, which reduces the temperature of the tire. The improved rolling resistance performance means that the tire has low resistance and low energy consumption during rolling. From the above tests, it can be seen that the polymer product tire of the present invention is used in automobile or aircraft tire products. On the one hand, it has good anti-skid performance under slippery road conditions. On the other hand, it can reduce the tire temperature during use and increase the service life. On the third hand, the low rolling resistance of the tire can reduce energy consumption.

[0130] Of course, the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and equal changes and improvements made by ordinary technicians in the technical field within the essential scope of the present invention should all fall within the scope of the patent coverage of the present invention.

[0131] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

[0132] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0133] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0134] The endpoints and any values ​​of the scope disclosed in the present application document are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0135] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

[0136] Moreover, any embodiment described in this document may be freely combined with one or more other embodiments described in this document, and the technical solutions or technical ideas formed thereby are deemed to be part of the original disclosure or original record of the present invention, and should not be regarded as new content that has not been disclosed or anticipated in this document, unless a person skilled in the art considers that the combination is obviously unreasonable.

Claims

1. A method for preparing polystyrene in-situ reinforced 1,2-polybutadiene rubber, comprising: (1) subjecting a styrene solution to a first polymerization reaction in the presence of a first molybdenum-based catalyst under a protective atmosphere to obtain a mixture containing polystyrene; (2) mixing the mixture containing polystyrene obtained in step (1) with a second solvent, butadiene and a second molybdenum-based catalyst, and performing a second polymerization reaction under a protective atmosphere to obtain an in-situ blended polystyrene / 1,2-polybutadiene rubber; The first molybdenum-based catalyst and the second molybdenum-based catalyst each include a molybdenum compound, an alkyl aluminum, and a phosphoric acid ester.

2. The preparation method according to claim 1, characterized in that: In step (1): The molar ratio of styrene, molybdenum compound, alkyl aluminum and phosphate is (100-6000):1:(5-30):(1-5); and / or, The concentration of the styrene solution is 0.96-1.92 mol / L.

3. The preparation method according to claim 1, characterized in that: The conditions of the first polymerization reaction in step (1) include: The temperature is 60-90°C, and / or the time is 8-12h; and / or, The protective atmosphere is nitrogen and / or an inert gas; and / or, The solvent used for the styrene solution is at least one of toluene, n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octane.

4. The preparation method according to claim 1, characterized in that: In step (2): The amount of the mixture containing polystyrene is such that the mass ratio of polystyrene to butadiene is (0.5-20):100, preferably (2-15):100, based on the mass of polystyrene; and / or, The molar ratio of butadiene, molybdenum compound, alkyl aluminum and phosphate is (500-8000):1:(5-30):(1-5), preferably (2000-6000):1:(10-24):(2-4).

5. The preparation method according to claim 1, characterized in that: The amount of the second solvent is such that the concentration of butadiene in the second solvent is 1-5 mol / L; and / or, The second solvent is selected from at least one of toluene, n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octane.

6. The preparation method according to claim 1, characterized in that: The conditions for the second polymerization reaction in step (2) include: The temperature is 40-80°C, and / or the reaction time is 4-12h, and / or the mixing method is stirring, preferably the stirring speed is 20-600rpm; and / or, The protective atmosphere is nitrogen and / or an inert gas.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The molybdenum compound is selected from at least one of molybdenum pentachloride, molybdenum tetrachloride and molybdenum dichloride; and / or, The alkyl aluminum is selected from at least one of trimethyl aluminum, tripropyl aluminum, tributyl aluminum, diisobutyl aluminum hydride, and meta-cresol aluminum; and / or, The phosphate ester is selected from at least one of triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, di(2-ethylhexyl) phosphate, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, triisopropylphenyl phosphate, and triisooctyl phosphate.

8. The preparation method according to any one of claims 1 to 6, characterized in that: The preparation method further comprises vulcanizing the in-situ blended polystyrene / 1,2-polybutadiene rubber obtained in step (2) with an auxiliary agent to obtain the polystyrene in-situ reinforced 1,2-polybutadiene rubber.

9. The preparation method according to claim 8, characterized in that: In parts by mass, relative to 100 parts of in-situ blended polystyrene / 1,2-polybutadiene rubber, the additives used for vulcanization include: 20-60 parts of carbon black, 1-3 parts of ZnO, 0.5-1.5 parts of stearic acid, 0.4-0.6 parts of accelerator, 0.4-0.8 parts of antioxidant, and 0.5-2 parts of vulcanizing agent.

10. The preparation method according to claim 8, characterized in that: The mixing steps before vulcanization include: Firstly, the in-situ blended polystyrene / 1,2-polybutadiene rubber and the additives other than the vulcanizing agent are mixed and kneaded, and then the vulcanizing agent is added and kneaded; and / or, The vulcanization conditions include: temperature 120-160° C., and / or time 1-60 min, and / or pressure 1-10 MPa.

11. A polystyrene in-situ reinforced 1,2-polybutadiene rubber, wherein the polystyrene in-situ reinforced 1,2-polybutadiene rubber is prepared by the preparation method according to any one of claims 1 to 10; Preferably, the mass content of the 1,2 structure of the polystyrene in-situ reinforced 1,2-polybutadiene rubber is 80%-85%, and / or the Mooney viscosity is 60-75.

12. Use of the polystyrene in-situ reinforced 1,2-polybutadiene rubber according to claim 11 in tires and / or tire products.

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