Synthetic rubber wet masterbatch, method for preparing the same, and use thereof

Abstract

The application provides a synthetic rubber wet masterbatch and a preparation method thereof. The method comprises the following steps: S1) obtaining a synthetic rubber glue solution by using a bulk polymerization method; S2) mixing fillers and / or additives with the synthetic rubber glue solution, and uniformly dispersing to obtain a composite; and S3) devolatilizing the composite to obtain a rubber masterbatch. The wet masterbatch is prepared by using a pure bulk polymerization glue solution. In the process of synthesizing the rubber glue solution by the bulk polymerization reaction, in order to reduce the viscosity of the system, only 0% to 30% of organic solvents are used; therefore, the amount of the organic solvents is very small or even can be not used. Compared with a dry masterbatch, the dispersibility of the fillers is greatly improved. After the synthetic rubber masterbatch is subjected to a closed mixing and an open mixing, and after vulcanization, it is found that the vulcanized rubber has excellent mechanical properties, wear resistance, rolling resistance and low heat generation.

Description

Technical Field

[0001] This invention belongs to the field of rubber composite material processing and production technology, and particularly relates to a wet process masterbatch for synthetic rubber, its preparation method and application. Background Technology

[0002] The wet-process masterbatch prepared with excellent filler dispersibility and application performance has been extensively studied by numerous research institutions and manufacturing companies both domestically and internationally. Patent CN102314270A mentions the application of a wet-process masterbatch rubber composition in tires. The patent describes a preparation process where two of the following liquids are first mixed: a turbid dispersion of rubber additives (antioxidants, stearic acid, resins, etc.), rubber latex, and filler slurry, and then mixed with another liquid. This preparation process is relatively complex, and the types of rubber additives that can be used are limited. Cabot Corporation in the United States developed a liquid-phase continuous manufacturing process for natural rubber / carbon black masterbatch using natural latex and carbon black slurry (US19970823411, CN97195156). This simplified the mixing process, shortened the mixing time, and reduced energy consumption and cost. However, it limited the types of masterbatch and fillers that could be used. Furthermore, the polar components of the latex adsorbed onto the filler surface disrupted the interaction between the filler and the rubber, significantly reducing the performance of the resulting rubber products. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a synthetic rubber wet process masterbatch, its preparation method and application. The method uses a significantly reduced amount of organic solvent or even no organic solvent at all, and the synthetic rubber wet process masterbatch obtained has excellent mechanical properties and wear resistance, low rolling resistance and low heat generation after vulcanization.

[0004] This invention provides a method for preparing synthetic rubber wet process masterbatch, comprising the following steps:

[0005] S1) Synthetic rubber compound was prepared by bulk polymerization;

[0006] S2) The filler and / or additives are mixed with the synthetic rubber liquid and dispersed evenly to obtain the composite.

[0007] S3) The composite is devolatilized to obtain rubber masterbatch.

[0008] The method for preparing synthetic rubber wet-process masterbatch provided by this invention significantly reduces the amount of organic solvent used, and may even eliminate the need for organic solvents altogether. The process employs a dry devolatilization method without agglomeration, resulting in a simple and energy-efficient preparation process. The synthetic rubber masterbatch prepared using this invention exhibits excellent filler dispersibility, and rubber products made from this synthetic rubber wet-process masterbatch possess superior mechanical properties, abrasion resistance, and low rolling resistance and heat generation.

[0009] This invention employs a bulk polymerization method to prepare a synthetic rubber compound. Specifically, it involves bulk polymerization of diolefin monomers and / or monoolefin monomers, with the concentration of the synthetic rubber compound being 1-40 wt%, preferably 5-25%. The concentration of the synthetic rubber compound is the same as the concentration of the dry rubber in the compound. In this invention, the diolefin monomers are selected from butadiene and isoprene. The synthetic rubber compound is a compound of one type of rubber or a mixture of two or more rubber compounds. To reduce the viscosity of the bulk polymerization system, this invention preferably adds a small amount of a good solvent for the rubber during the polymerization process; based on the total mass of the olefin monomers and the good solvent, the concentration of the good solvent is 0-30 wt%.

[0010] This invention involves mixing fillers and / or additives with synthetic rubber and dispersing them uniformly to obtain a composite. The fillers and / or additives can be directly added to the synthetic rubber solution; alternatively, they can be added to the synthetic rubber solution after being prepared into a suspension with a solvent. If the fillers and / or additives are prepared into a suspension with a solvent, the solvent used is preferably a good solvent for rubber; the type of good solvent can be the same as or different from the type of good solvent used in step S1).

[0011] In this invention, the filler is a solid filler commonly used in rubber products; the filler is preferably one or more of carbon black, silica, kaolin, calcium carbonate, graphene and carbon nanotubes, more preferably carbon black and / or silica; the particle size of the carbon black is preferably 1~500nm, more preferably 11~100nm; the particle size of the silica is 10~50nm, more preferably 15~40nm.

[0012] In this invention, the additive is selected from one or more of surfactants, antioxidants, plasticizers, coupling agents, flame retardants, resins, and dyes.

[0013] The activator is selected from zinc oxide and / or stearic acid;

[0014] The antioxidant is selected from one or more of amine antioxidants, phenolic antioxidants, quinoline antioxidants, and protective waxes;

[0015] The plasticizer improves the processing properties of the rubber; the plasticizer is selected from processing oils and / or liquid rubbers; the processing oil is selected from one or more of aromatic oils, paraffin oils, and naphthenic oils; the liquid rubber has a weight-average molecular weight of 3 × 10⁻⁶. 3 ~1×10 5 ;

[0016] The coupling agent is used to improve the interaction between the filler (such as silica) and the rubber matrix; the coupling agent is selected from one or more of silane coupling agents, titanate coupling agents and aluminate coupling agents; the mass ratio of the filler to the coupling agent is (10:0.5) to (10:2.0), preferably 10:1.

[0017] The resin is selected from tackifying resins and / or reinforcing resins.

[0018] In this invention, based on 100 parts of dry rubber in synthetic rubber solution, 0 to 150 parts of filler are used, preferably 10 to 120 parts, and more preferably 20 to 100 parts.

[0019] 1 to 12 parts of surfactant, preferably 3 to 10 parts;

[0020] 0.5 to 12 parts of antioxidant, preferably 1 to 6 parts;

[0021] 0 to 50 parts of plasticizer, preferably 2 to 40 parts, more preferably 3 to 20 parts;

[0022] 0.5 to 20 parts of resin, preferably 2 to 12 parts.

[0023] After obtaining the composite, the present invention devolatilizes the composite to obtain rubber masterbatch. In the present invention, the devolatilization is a dry devolatilization process, which does not involve agglomeration; the monomers that were not involved in the polymerization reaction are purified and then participate in the bulk polymerization reaction to prepare rubber; the removed solvent can be recycled.

[0024] The present invention preferably involves further internal mixing and vulcanization after obtaining the rubber masterbatch; during internal mixing, one or more of the following are preferably added: vulcanizing agent, accelerator, anti-scorching agent and anti-reversion agent.

[0025] In this invention, the vulcanizing agent is an auxiliary agent that crosslinks rubber molecular chains under high temperature and high pressure. The vulcanizing agent is selected from one or more of sulfur, sulfur donors, and peroxides. In specific embodiments, if it is a diene rubber, the vulcanizing agent is preferably sulfur and / or a sulfur donor; if it is a monoolefin rubber, the vulcanizing agent is a peroxide.

[0026] The accelerator is selected from one or more of thiazole accelerators, sulfenamide accelerators, thiuram accelerators, dithiocarbamate accelerators, and diphenylguanidine accelerators; in the specific embodiment, the accelerator is designated as NS.

[0027] The anti-scorching agent is an auxiliary agent that slows down the early scorching reaction before the scorching operation. The anti-scorching agent is selected from one or more of organic acids, nitrosamines and thioimides.

[0028] In this invention, the anti-reversion agent is an additive that prevents the rubber from undergoing reversion during the vulcanization process.

[0029] Based on 100 parts by weight of dry rubber in synthetic rubber compound, the amounts of vulcanizing agent, accelerator, scorch inhibitor, and anti-reversion agent added are as follows:

[0030] 0.2 to 12 parts of vulcanizing agent, preferably 0.5 to 6 parts; in a specific embodiment, the amount of vulcanizing agent is 1.6 parts;

[0031] The accelerator is used in an amount of 0.2 to 8 parts, preferably 0.5 to 5 parts; in a specific embodiment, the amount of accelerator is 2.0 parts.

[0032] The amount of anti-scorching agent is 0 to 1 part, preferably 0.1 to 0.5 parts;

[0033] And 0 to 1 part of an anti-sulfurization reversion agent, preferably 0.1 to 0.5 parts.

[0034] In this invention, the synthetic rubber wet process masterbatch is vulcanized to obtain vulcanized rubber; the vulcanized rubber has significant advantages in mechanical strength, abrasion performance, rolling resistance and heat generation performance.

[0035] This method for preparing synthetic rubber wet masterbatch uses pure bulk polymerization solution. During the bulk polymerization reaction to synthesize the rubber solution, only 0% to 30% organic solvent is used to reduce the system viscosity; thus, the amount of organic solvent used in this invention is very small, or even negligible. Furthermore, unreacted monomers can be refined and reused in the polymerization reaction, and the small amount of organic solvent used can be recycled. The process does not generate any waste. The post-treatment process does not involve coagulation and employs a dry devolatilization process, different from traditional wet masterbatch, simplifying the process.

[0036] Compared with dry-process masterbatch, the wet-process synthetic rubber masterbatch prepared by the process of this invention has significantly improved filler dispersibility. After the synthetic rubber masterbatch is processed by internal mixing and open milling and then vulcanized, the sample obtained is subjected to performance testing. It is found that the vulcanized rubber has excellent mechanical properties and wear resistance, low rolling resistance and low heat generation. Detailed Implementation

[0037] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of a synthetic rubber wet process masterbatch and its preparation method provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0038] Comparative Example 1

[0039] Dry mixing technology was used: 100 parts trans-butyl ester rubber, 5 parts zinc oxide, 3 parts stearic acid, 60 parts silica, 6 parts silane coupling agent, 2 parts antioxidant 4020, 1 part antioxidant RD, 1 part protective wax, and 3 parts environmentally friendly aromatic oil were mixed in an internal mixer. The mixture was then sheeted on a two-roll mill to obtain a first-stage masterbatch. The first-stage masterbatch was left to stand at room temperature for 2 hours. The first-stage masterbatch, 2.0 parts accelerator NS, and 1.6 parts sulfur were mixed evenly in an internal mixer, and the mixture was sheeted on a two-roll mill to obtain a final compound, which was left to stand at room temperature for 24 hours. The final compound was vulcanized at 150°C. The corresponding performance tests were performed according to the equipment, standards, or methods described in Table 1.

[0040] Example 1

[0041] Trans-butadiene-pentadiene rubber (10% dry rubber mass, the remainder being unreacted monomers) was obtained by pure bulk polymerization of butadiene and isoprene monomers. To 1000 parts of this trans-butadiene-pentadiene rubber compound, 5 parts zinc oxide, 3 parts stearic acid, 60 parts silica, 6 parts silane coupling agent, 2 parts antioxidant 4020, 1 part antioxidant RD, 1 part protective wax, and 3 parts environmentally friendly aromatic oil were added. After uniform dispersion under stirring and shearing, the mixture was devolatilized. The resulting monomers were refined and then reintroduced into the polymerization system for further polymerization. The resulting wet masterbatch was mixed thoroughly in an internal mixer with 2.0 parts accelerator NS and 1.6 parts sulfur. The mixture was sheeted on an open mill and left to stand at room temperature for 24 hours. The final compound was vulcanized at 150°C. The corresponding performance tests were conducted according to the equipment, standards, or methods described in Table 1.

[0042] Example 2:

[0043] Trans-butadiene-pentadiene rubber (25% dry rubber mass, the remainder being unreacted monomers) was obtained by polymerizing butadiene and isoprene monomers using a pure bulk polymerization process. A suspension was formed by mixing 5 parts zinc oxide, 3 parts stearic acid, 60 parts silica, 6 parts silane coupling agent, 2 parts antioxidant 4020, 1 part antioxidant RD, 1 part protective wax, and 3 parts environmentally friendly aromatic oil in 300 parts n-hexane. The n-hexane suspension containing silica and other rubber additives was then added to 400 parts of the trans-butadiene-pentadiene rubber solution. After uniform dispersion under stirring and shearing, the mixture was devolatilized. The monomers generated from the devolatilization were purified and reintroduced into the polymerization system for further polymerization. The purified n-hexane was recycled. The resulting wet masterbatch was uniformly mixed with 2.0 parts accelerator NS and 1.6 parts sulfur in an internal mixer. The mixture was sheeted on an open mill and left to stand at room temperature for 24 hours. The final compound was vulcanized at 150°C. Perform the corresponding performance tests according to the equipment, standards, or methods described in Table 1.

[0044] Example 3:

[0045] A bulk polymerization process employing solvent viscosity reduction was used to produce a trans-butadiene-pentadiene rubber compound (16% dry rubber mass, 20% heptane solvent mass, and 64% unreacted monomers) obtained by polymerizing butadiene and isoprene monomers. 5 parts zinc oxide, 3 parts stearic acid, 60 parts silica, 6 parts silane coupling agent, 2 parts antioxidant 4020, 1 part antioxidant RD, 1 part protective wax, and 3 parts environmentally friendly aromatic oil were added to 625 parts of the trans-butadiene-pentadiene rubber compound. After uniform dispersion under stirring and shearing, the compound was devolatilized. The resulting monomers were purified and reintroduced into the polymerization system for further polymerization. The purified hexane was recycled. The resulting wet masterbatch was uniformly mixed with 2.0 parts accelerator NS and 1.6 parts sulfur in an internal mixer. The compound was sheeted on an open mill and left to stand at room temperature for 24 hours. The final compound was vulcanized at 150°C. Relevant performance tests were conducted according to the equipment, standards, or methods described in Table 1.

[0046] Table 1. Equipment and Standards or Methods Used

[0047]

[0048] Table 2 Performance test results of Examples 1-3 and Comparative Example 1

[0049]

[0050] As can be seen from the above examples, compared with the samples prepared by the traditional dry rubber mixing process (Comparative Example 1), the filler dispersion grade is significantly improved; the wet masterbatch prepared by the technology of this invention, after vulcanization, shows an increase in tensile strength of 0.8~2.4MPa, an increase in tear strength of 7~10KN / m, an increase in resilience of 7~9 units, a decrease in compression heat generation of 6.0~7.7℃, a decrease in tanδ@60℃ (characterizing rolling resistance) of about 50%, and a decrease in wear volume of about 30%.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing vulcanizate, characterized in that, The steps are as follows: Trans-butadiene-pentadiene rubber compound was obtained by polymerizing butadiene and isoprene monomers using a pure bulk polymerization process. The dry rubber accounted for 25% of the compound, with the remainder being unreacted monomers. A suspension was formed by stirring 5 parts zinc oxide, 3 parts stearic acid, 60 parts silica, 6 parts silane coupling agent, 2 parts antioxidant 4020, 1 part antioxidant RD, 1 part protective wax, and 3 parts environmentally friendly aromatic oil in 300 parts n-hexane. The n-hexane suspension containing silica and other rubber additives was then added to 400 parts of the trans-butadiene-pentadiene rubber compound. After uniform dispersion under stirring and shearing, the mixture was devolatilized. The monomers generated from the devolatilization were purified and then reintroduced into the polymerization system for another polymerization reaction. The purified n-hexane was recycled. The resulting wet masterbatch was uniformly mixed with 2.0 parts accelerator NS and 1.6 parts sulfur in an internal mixer. The mixed compound was sheeted on an open mill and left to stand at room temperature for 24 hours. The final compound was vulcanized at 150°C to obtain vulcanized rubber.

2. The preparation method according to claim 1, characterized in that, The particle size of the silica is 10~50nm.

3. A vulcanizate, prepared by the method described in any one of claims 1 to 2.

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