Carbon black-reinforced rubber and method for its production

Abstract

The present application relates to the field of carbon black reinforced rubber, in particular to carbon black reinforced rubber and a preparation method thereof.The preparation method of the carbon black reinforced rubber provided by the present application solves the problems of carbon black particle coarsening or sedimentation in the carbon black dispersion liquid during storage and standing or long-time homogenization of multiple phases by recycling breaking and dispersing carbon black in an organic solvent and then mixing the carbon black with a raw rubber solution in a turbulent flow, and the carbon black can be stably dispersed in the organic solvent in nanometer size without prior surface modification treatment, and the carbon black reinforced rubber can be produced by mixing the carbon black with the raw rubber solution, the subsequent conveying, mixing and flocculation are continuous and fast, and there are no problems such as obvious carbon black coarsening and sedimentation, so that high-quality dispersion of the carbon black in the raw rubber matrix can be realized without special equipment configuration and process control, the production device and process are mature technologies in the field of fluid mixing, and highly meet the needs of industrial production, and the carbon black reinforced rubber can be well produced by using a continuous process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of carbon black reinforced rubber, in particular to carbon black reinforced rubber and a preparation method thereof. BACKGROUND

[0002] Carbon black is the earliest and most widely used nano reinforcing material in the rubber industry. Although the affinity of carbon black and rubber is acceptable, it is still difficult to achieve good dispersion of carbon black particles with extremely small particle size in the rubber matrix through traditional mixing process, so that the optimal reinforcing effect cannot be achieved, and this situation is particularly prominent for low structure carbon black of series 1-3. In conventional mixing production, the dispersion effect of fine particle size and low structure carbon black can be improved by multi-stage masterbatching, but this inevitably increases the process cost and reduces the mixing production efficiency. At the end of the 20th century, the rubber liquid mixing technology proposed by Cabot Corporation of the United States provided an effective solution to the dispersion of nano fillers in rubber. However, since the dispersion medium is water, the technology can only prepare natural rubber / carbon black wet rubber by mixing and flocculating carbon black aqueous slurry and natural latex. Although the technology can be extended to emulsion polymerized styrene-butadiene, nitrile rubber, and chlorobutyl rubber systems, it is still based on the latex system of water-based dispersion medium. This brings great limitations to the selection of rubber matrix, and cannot be applied to rubber materials with higher structure regularity prepared based on solution polymerization, such as isoprene rubber, solution polymerized styrene-butadiene rubber, and cis-butadiene rubber. In view of this problem, Qingdao Yewei Research Institute introduced the solvent-based wet mixing technology based on synthetic rubber, commonly known as "liquid gold" technology, in about 2005. The technology can achieve good dispersion of carbon black, white carbon black and other nano reinforcing fillers in natural rubber and synthetic rubber obtained by different polymerization processes.

[0003] The biggest technical difficulty of carbon black reinforced synthetic rubber wet rubber based on solvent method is how to realize the stable dispersion of carbon black in organic solvent in nanometer size. The common method is to use coupling agent to modify the surface of pre-carbon black to improve its dispersion performance in organic solvent. Patent CN103205001A directly adds carbon black and coupling agent into the rubber solution, realizes coarse dispersion by stirring, then sets the variable diameter or flow angle in the high-pressure pipeline of the mixed liquid to realize the dispersion of carbon black nanoparticles in the solution under the action of turbulence and coupling agent, and finally obtains carbon black reinforced composite material by flocculation and drying. However, both methods have certain disadvantages. The former may have certain difficulties in the selection and grafting modification process of coupling agent, and the latter has high requirements for processing equipment and process parameters. SUMMARY

[0004] Therefore, the present application provides carbon black reinforced rubber and a preparation method thereof.

[0005] The present application provides a preparation method of carbon black reinforced rubber, comprising the following steps:

[0006] S1) performing cyclic crushing and dispersion of carbon black in an organic solvent to obtain a carbon black dispersion liquid; the cyclic crushing and dispersion mode comprises emulsification treatment or high-pressure homogenization treatment; the rotation speed of the emulsification treatment is 3000 rpm-10000 rpm, and the emulsification treatment time is 20 min-30 min; the pressure of the high-pressure homogenization treatment is 500 bar-2000 bar, and the high-pressure homogenization treatment time is 10 min-30 min;

[0007] S2) performing turbulent mixing of a raw rubber solution and the carbon black dispersion liquid obtained in step S1) and flocculation to obtain carbon black reinforced rubber.

[0008] The concentration of the carbon black dispersion liquid is 0.01 g / mL-0.10 g / mL, preferably 0.02 g / mL-0.05 g / mL; the iodine adsorption value of the carbon black in the carbon black dispersion liquid is ≥80 g / kg. The carbon black in the carbon black dispersion liquid is preferably selected from rubber carbon black or pigment carbon black; the organic solvent in the carbon black dispersion liquid is preferably selected from one or more of n-hexane, cyclohexane, benzene, toluene and xylene. The concentration of the raw rubber in the raw rubber solution is 0.01 g / mL-0.10 g / mL, preferably 0.04 g / mL-0.08 g / mL. The raw rubber in the raw rubber solution is preferably selected from one or more of natural rubber, eucommia rubber, isoprene rubber, cis-butadiene rubber, emulsion polymerized styrene-butadiene rubber, solution polymerized styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, chlorobutyl rubber, nitrile rubber and hydrogenated nitrile rubber; the solvent in the raw rubber solution is an organic solvent, which is the same as the organic solvent in the carbon black dispersion liquid. The weight ratio of the raw rubber in the raw rubber solution to the carbon black in the carbon black dispersion liquid is 100:(40-60), preferably 100:50.

[0009] The preparation method of the carbon black reinforced rubber provided by the application comprises the following steps: firstly, the carbon black is subjected to cyclic breaking and dispersion in an organic solvent to obtain a carbon black dispersion liquid. The cyclic breaking and dispersion mode comprises emulsification treatment or high-pressure homogenization treatment. The carbon black is subjected to breaking treatment for a certain time length, so as to sufficiently reduce the size of the carbon black in a liquid phase environment through sufficient shearing action and capacity input, which is a prerequisite for realizing the dispersion of the carbon black in a raw rubber matrix. The shearing force applied to the carbon black particles by simple high-speed stirring cannot overcome the van der Waals force of the nanoparticles, and cannot break the carbon black particles into nanoscale. The rotation speed of the emulsification treatment is 3000 rpm to 10000 rpm, and preferably 5000 rpm to 8000 rpm. The emulsification treatment time is 20 min to 30 min. The pressure of the high-pressure homogenization treatment is 500 bar to 2000 bar, and preferably 1000 bar to 1800 bar. The high-pressure homogenization treatment time is 10 min to 30 min. In some embodiments of the application, the emulsification treatment is performed by using a recyclable continuous emulsification pump. The high-pressure homogenization treatment is performed by using a recyclable continuous high-pressure homogenizer.

[0010] After obtaining the carbon black dispersion liquid, the raw rubber solution and the carbon black dispersion liquid are subjected to turbulent mixing. Preferably, the carbon black dispersion liquid is prepared first, and then the carbon black dispersion liquid is directly subjected to turbulent mixing in the raw rubber solution without being placed. Specifically, the carbon black is subjected to cyclic breaking and dispersion in an organic solvent to obtain a carbon black dispersion liquid, and then the obtained carbon black dispersion liquid is directly subjected to turbulent mixing with the raw rubber solution without being placed. In some embodiments of the application, the carbon black is subjected to stirring in an organic solvent, and then is subjected to cyclic breaking and dispersion to obtain a carbon black dispersion liquid. Then, the obtained carbon black dispersion liquid is directly and co-currently conveyed to a static mixer with the raw rubber solution to perform turbulent mixing. The carbon black dispersion liquid is directly subjected to turbulent mixing with the raw rubber solution without being placed in the application. On the one hand, this process is more suitable for continuous production, and more importantly, this process can prevent the aggregation and coarsening of the carbon black.

[0011] The turbulent mixing is performed by using a static mixer. The mixing unit of the static mixer is one or a combination of multiple types selected from the group consisting of SK type, SV type and SX type. More specifically, the length of the mixing unit of the static mixer is 200 mm to 600 mm. The static mixer is a pipeline mixer. The outer wall of the pipeline is provided with a feeding port and a discharging port. The inside is spliced by mixing units along the length of the pipeline. The type of the mixing unit can form a high degree of turbulence in a short time. In addition, in order to ensure the uniformity of the mixing of the carbon black slurry and the rubber solution, the total length of the mixing unit cannot be too small, but if it is too long, the residence time of the broken carbon black particles in the liquid phase environment will be prolonged, which will cause aggregation and coarsening.

[0012] After the turbulent mixing of the raw rubber solution and the carbon black dispersion liquid, the material after the turbulent mixing is flocculated. The flocculation methods include ethanol flocculation, hot water flocculation, high-temperature steam flocculation, spray drying flocculation, etc. The ethanol flocculation is preferred in the present application; the ethanol flocculation is faster, which is conducive to inhibiting the aggregation of carbon black particles in the flocculation process. In addition, from the subsequent drying, the specific heat of ethanol is much lower than that of water, and the advantages in drying energy consumption and efficiency are significant.

[0013] After the turbulent mixing of the raw rubber solution and the carbon black dispersion liquid, the material after the turbulent mixing is flocculated. The flocculation methods include ethanol flocculation, hot water flocculation, high-temperature steam flocculation, spray drying flocculation, etc. The ethanol flocculation is preferred in the present application; the ethanol flocculation is faster, which is conducive to inhibiting the aggregation of carbon black particles in the flocculation process. In addition, from the subsequent drying, the specific heat of ethanol is much lower than that of water, and the advantages in drying energy consumption and efficiency are significant.

[0014] The present application also provides a carbon black reinforced rubber prepared by the preparation method of any one of the above technical solutions.

[0015] The preparation method of the carbon black reinforced rubber provided by the present application solves the problems of carbon black particle coarsening or sedimentation in the storage and standing or long-time homogenization of the carbon black dispersion liquid by circulating crushing and dispersing the carbon black in the organic solvent and then mixing it with the raw rubber solution. Compared with the prior art, the present application can realize the stable dispersion of carbon black in the organic solvent in nanometer size and the production of carbon black reinforced rubber with the raw rubber solution without the need for prior surface modification treatment of the carbon black. In addition, since the carbon black dispersion liquid is prepared by high-strength crushing, the subsequent transportation, mixing and flocculation are continuous and fast, and there is no obvious problem of carbon black coarsening and sedimentation, so the high-quality dispersion of carbon black in the raw rubber matrix can be realized without special equipment configuration and process control. The production device and process are mature technologies in the field of fluid mixing, and are highly consistent with the needs of industrial production. The continuous process can be well used to produce carbon black reinforced rubber. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The flow chart of the preparation method of the carbon black reinforced rubber of the present application;

[0017] Figure 2 The physical map of the carbon black reinforced rubber nanocomposite obtained in Example 2 of the present application. DETAILED DESCRIPTION

[0018] The present application discloses a carbon black reinforced rubber and its preparation method and vulcanized rubber. The skilled in the art can improve the process parameters according to the content of the present application. It is particularly pointed out that all similar replacements and changes are obvious to the skilled in the art, and they are considered to be included in the present application. The method and application of the present application have been described by the preferred embodiments, and the related personnel can obviously change or appropriately change and combine the method and application of the present application without departing from the content, spirit and scope of the present application, to realize and apply the present application technology.

[0019] The preparation method of the carbon black reinforced rubber of the present application mainly includes four steps:

[0020] 1) Preparation of carbon black dispersion slurry;

[0021] 2) Preparation of raw rubber solution;

[0022] 3) Co-current transportation and high-speed mixing of carbon black slurry and raw rubber solution;

[0023] 4) Flocculation and drying of raw rubber / carbon black mixed solution.

[0024] Specifically, as shown in Figure 1 , the flow chart of the preparation method of the carbon black reinforced rubber of the present application is shown. As can be seen from Figure 1 , the carbon black particles and raw rubber are dispersed in the organic solvent to obtain carbon black dispersion liquid and raw rubber solution, then the two are co-currently transported and high-speed mixed, and then flocculated with ethanol to obtain masterbatch wet rubber, and then pressed, air-dried at room temperature and air-dried, to finally obtain the rubber product. Figure 1

[0025] The present application is further described in combination with the following examples:

[0026] Examples 1-4

[0027] ​Carbon black is weighed according to a set concentration and added to a specific solvent, and a carbon black dispersion liquid with fluidity is obtained after simple stirring, and then the carbon black dispersion liquid is added to a high-strength dispersion device for cyclic crushing, while a sufficient amount of raw rubber solution is prepared according to a specific concentration by using the same solvent. The carbon black dispersion liquid after a certain time of crushing treatment is directly discharged through an external pipeline without placement, while the prepared raw rubber solution is pumped into the external pipeline through a rotor pump. The flow rate of the rotor pump is adjusted according to a set raw rubber / carbon black ratio, and then the carbon black dispersion liquid and the raw rubber solution are transported to a static mixer from two different inlets respectively, so that the two are fully turbulent and uniformly mixed in the mixer. A plurality of nozzles with a diameter of about 2 mm are installed in parallel at the outlet position of the static mixer, and the carbon black / raw rubber mixed liquid is discharged through the nozzles and directly introduced into excess ethanol for flocculation. The flocculated wet rubber is fished out and rolled into a sheet with a thickness of less than 1 mm by using a press. After the wet rubber sheet is dried at room temperature for 48 hours, it is hung in a blast drying oven at 120°C for 5 hours, and then cooled to obtain a carbon black reinforced rubber nanocomposite with good dispersion state. As shown in Figure 2 Figure 2 It is a physical diagram of the carbon black reinforced rubber nanocomposite obtained in Example 2 of the present application.

[0028] The selection of each material and the setting of process parameters in Examples 1-4 are shown in Table 1:

[0029] Table 1

[0030]

[0031] For Examples 1-4, the physical properties of the wet process masterbatch were evaluated using a standard formula. The raw materials in the evaluation formula include raw rubber, carbon black, zinc oxide, stearic acid, accelerator TBBS, and sulfur. The raw rubber and carbon black are present together in the form of a masterbatch, and based on 100 phr of raw rubber (50 phr of carbon black) in the masterbatch, the amounts of zinc oxide, stearic acid, accelerator TBBS, and sulfur are 5 phr, 2 phr, 0.7 phr, and 2.25 phr, respectively.

[0032] The physical property test results of the wet process masterbatch after mixing and vulcanization according to the foregoing formula are shown in Table 2:

[0033] Table 2

[0034]

[0035] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes within the technical scope disclosed by the present application according to the technical solution and inventive concept of the present application, which should be covered within the protection scope of the present application.​

Claims

1. Process for the preparation of carbon black reinforced rubber, characterized in that, The preparation method realizes stable dispersion of carbon black in an organic solvent in nanometer size without chemical modification of the carbon black and produces carbon black reinforced rubber with a raw rubber solution, and comprises the following steps: S1) performing cyclic crushing dispersion of the carbon black in the organic solvent to obtain a carbon black dispersion liquid; the cyclic crushing dispersion mode comprises emulsification treatment or high-pressure homogenization treatment; the rotation speed of the emulsification treatment is 3000 rpm-10000 rpm, and the emulsification treatment time is 20 min-30 min; the pressure of the high-pressure homogenization treatment is 500 bar-2000 bar, and the high-pressure homogenization treatment time is 10 min-30 min; S2) performing turbulent mixing of the raw rubber solution and the carbon black dispersion liquid obtained in step S1) and flocculation to obtain carbon black reinforced rubber; the turbulent mixing is performed by using a static mixer, and the mixing unit of the static mixer is one or more of SK type, SV type and SX type in series combination; The length of the mixing unit of the static mixer is 200 mm-600 mm.

2. The production method according to claim 1, characterized by, The iodine adsorption value of the carbon black is ≥80 g / kg.

3. The production method according to claim 1, characterized by, The concentration of the carbon black dispersion liquid is 0.01 g / mL-0.10 g / mL.

4. The method of claim 1, wherein, The concentration of the raw rubber solution is 0.01 g / mL-0.10 g / mL.

5. The preparation method according to claim 1, characterized in that, The weight ratio of the raw rubber in the raw rubber solution to the carbon black in the carbon black dispersion liquid is 100:(40-60).

6. The method of claim 1, wherein, The carbon black is selected from rubber carbon black or pigment carbon black; The raw rubber is selected from one or more of natural rubber, eucommia rubber, isoprene rubber, cis-butadiene rubber, emulsion polymerized styrene-butadiene rubber, solution polymerized styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, chlorobutyl rubber, nitrile rubber and hydrogenated nitrile rubber; The organic solvent is selected from one or more of n-hexane, cyclohexane, benzene, toluene and xylene.

7. The preparation method according to claim 1, characterized in that, The flocculation is performed by using ethanol.

8. Carbon black reinforced rubber, characterized in that The carbon black reinforced rubber is obtained by the preparation method in any one of claims 1-7.

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