CN114407266A - Preparation method of carbon black/natural latex composite material - Google Patents

Abstract

The invention belongs to the technical field of wet mixing of natural rubber, and relates to a preparation method of a carbon black natural latex composite material, which comprises the steps of firstly, respectively mixing a prepared carbon black aqueous solution and a potassium oleate aqueous solution with foamed natural latex, then, stirring at a high speed to ensure that the natural latex is fully contacted with carbon black, preparing carbon black master batch by a foaming flocculation method, and finally, putting the carbon black master batch into an internal mixer for mixing, wherein the obtained mixed rubber has uniform quality, not only the physical property and the dynamic mechanical property are obviously improved compared with the mixing process of a conventional wet method and a conventional dry method, but also the aging property is greatly improved, simultaneously, the carbon black achieves better dispersion effect in the natural latex, can solve the problems of filler residue and overlarge energy consumption caused by acid flocculation, shorten the vulcanization time, greatly improve the rubber production efficiency and improve the rubber property, the problem of environmental pollution caused by flying of the rubber additive is avoided, and the rubber additive is green, environment-friendly, energy-saving and consumption-reducing.

Description

A kind of preparation method of carbon black/natural latex composite material

Technical field:

The invention belongs to the technical field of natural rubber wet kneading, and relates to a method for preparing a carbon black/natural latex composite material, which can shorten the production cycle, make the reinforcing fillers microscopically dispersed in the natural rubber, and improve the rubber properties.

Background technique:

Kneading is the process of mixing rubber and various raw materials evenly. It is implemented by an open mill or an internal mixer. It is the first and most important step in the processing and production of rubber materials. Wet kneading is a process in which the rubber in latex state is mixed with the pre-dispersed reinforcing filler dispersion system uniformly, so that the reinforcing filler particles are uniformly dispersed in the latex system, and the rubber and filler composite material is formed by flocculation and co-precipitation. .

The traditional mixing method in the rubber industry is the multi-stage mixing method of the internal mixer. However, the viscoelasticity of the rubber makes the temperature rise faster due to the continuous shearing during the mixing process. The safety of rubber processing, the mixing process is very short, making it difficult for the dispersion of rubber additives in rubber to achieve an ideal state; in order to improve the mixing efficiency, the rubber industry has developed new mixing methods and processes, including low-temperature one-shot method, Tandem mixing and continuous mixing, etc. Although the new mixing technology can improve the mixing efficiency and quality, due to the essential characteristics of rubber, the dispersion level of the filler in the mixed rubber still cannot reach the expected value, especially Natural rubber composites prepared by wet mixing.

Carbon black is a typical component in rubber. It can only play a role if it is evenly distributed in the rubber, which can make the elastic network of the rubber have unique structural properties. However, in actual production, it is difficult for carbon black to be uniformly dispersed in the rubber. It needs to be realized by means of high shear force and high power mixer. Natural latex is a milky white colloid composed of cis-1,4-polyisoprene, water, a small amount of protein and phospholipids, and has good film-forming properties. The coagulated raw rubber has good physical properties, including high Elasticity and high tensile strength, etc., are widely used in medicine and life fields, making tablet coatings, transdermal agents and condoms, as well as adhesives, carpets, leather boards, various gloves and balloons. Natural rubber is prepared from natural latex through the steps of collection, coagulation, washing and drying, among which coagulation is an important step in the formation of natural rubber.

The carbon black masterbatch in the prior art has problems such as low dispersity of reinforcing filler, cumbersome production process (including high-energy-consuming mixing), and low coagulation efficiency when carbon black is mixed with latex. The research found that although the wet mixing process can improve the micro-dispersion degree of carbon black filler, because the flocculation and drying methods are mostly chemical means such as acid flocculation, it will affect the performance of rubber products. For example, Chinese Patent 201110064299.3 discloses a method for preparing a wet-kneaded natural rubber material, comprising the following steps: A. The preparation of the slurry The slurry is composed of silica dry material, deionized water, coupling agent and surfactant , the preparation procedure is: 1) Soak 15-40% silica dry material in 60-85% deionized water, soaking time is 3-6h; 2), add 1-10% of silica dry material content Coupling agent, 0.2-5% surfactant, and mechanical stirring to make white carbon black dry material, coupling agent and surfactant mix uniformly to make white carbon black slurry; B. Grinding the above slurry with a grinding machine To the silica water dispersion that the sedimentation amount is less than 80mg/h; C, make latex mixture 1), get the field latex of natural rubber or the natural latex that is concentrated by centrifugation with dry rubber content of 15-60%; 2) , Add the prepared silica water dispersion into the latex, and stir at room temperature for 20-50 minutes; 3), the latex and the silica water dispersion are uniformly mixed into a latex mixture; D, flocculation, washing and dehydration 1), add 0.3-1% acetic acid of the total amount of the mixed solution to the mixed solution after mixing to make its pH value 3-5, the latex is uniformly flocculated and co-precipitated with silica; 2), The solidified rubber is washed with clean water to remove excess acetic acid, and washed and dehydrated by a rubber washing machine; 3) The dehydrated rubber is sent to a rubber granulator for granulation, and then the rubber granules are sent to the box type. Dry in a drying cabinet, the temperature is 90-120°C, and the drying time is 4-6h; E. After drying is complete, it is the natural rubber compound; the preparation method of a zeolite rubber composite material disclosed in Chinese Patent No. 201811575766.7, It includes the following steps: (1) prepare raw materials in proportion by mass: NR100; zinc oxide 3-5; stearic acid 1-3; antioxidant 4010NA1; accelerator CZ1-1.5; sulfur 2; zeolite powder 1-50; The zeolite powder is added into distilled water, mixed with natural rubber latex after stirring evenly, and then stirred by hand with a glass rod, while slowly adding acetic acid solution to flocculate; Finally, after dehydration in an electric heating blast box and drying to a constant weight in a vacuum drying box, the zeolite/NR wet-process co-precipitated glue was obtained; (3) an anti-aging agent, an accelerator, stearic acid, and zinc oxide were added in turn on the open mill. , zeolite and sulfur are mixed evenly by conventional mixing methods to obtain a mixed rubber; (4) the positive vulcanization time t of the mixed rubber is measured with a rubber vulcanizer. Compound rubber vulcanization molding. The unavoidable defects of the acid flocculation method will not only affect the health of the operators, but also corrode the equipment. The long-term drying after flocculation will easily produce acid gases that affect the environment. If the strong acid is not cleaned properly, it will also affect the subsequent vulcanization time. The vulcanization time of the rubber compound will have a hysteresis phenomenon in an acidic environment, which is easy to cause over-vulcanization and affect the performance of rubber products. Therefore, a preparation method of carbon black natural latex composite material was developed and designed to obtain a wet masterbatch with uniform dispersion of carbon black.

Invention content:

The purpose of the present invention is to overcome the shortcomings of the prior art, to design a preparation method of carbon black natural latex composite material, to improve the dispersion of carbon black in rubber, and then to make the mixed rubber have better performance.

In order to achieve the above purpose, the preparation method of carbon black/natural latex composite material involved in the present invention is a foaming self-flocculation method, and the specific process includes three steps: preparing carbon black aqueous solution, preparing potassium oleate aqueous solution, and preparing carbon black/natural latex composite material. steps:

(1) Preparation of carbon black aqueous solution: mix 60 parts by mass of powdered carbon black with deionized water to prepare a 25wt% carbon black aqueous solution;

(2) preparation of potassium oleate aqueous solution: 1.5g potassium oleate is mixed with deionized water to make 10wt% potassium oleate aqueous solution, the potassium oleate aqueous solution is placed on the magnetic stirrer that rotating speed is 20rpm, and the temperature is 70 Stir for 30min under the condition of ℃, make potassium oleate fully dissolve in deionized water and generate foam;

(3) Preparation of carbon black/natural latex composite material:

The potassium oleate aqueous solution was mixed with 166.67 parts by mass of 60wt% NRL (natural rubber latex), stirred for 5min under the condition of a frequency of 10-20HZ, and foamed;

Mixing the carbon black aqueous solution with the foamed NRL, stirring until flocculation, to obtain a carbon black masterbatch;

The carbon black masterbatch is compressed and dried, processed to a dry rubber level, and the drying temperature is 100° C. to obtain a carbon black/natural latex composite material that is foamed by containing potassium oleate.

The carbon blacks involved in the present invention include N115, N234, cracked carbon blacks and other carbon black materials for making rubber products and tire industry.

After the carbon black/natural latex composite material according to the present invention is put into an internal mixer, the mixed rubber can be obtained by internal mixing at a temperature of 100° C. and a rotation speed of 80 r/min.

Compared with the prior art, the present invention utilizes a wet kneading process to foam the natural latex through potassium oleate, so that the water dispersion of carbon black and the natural latex are fully contacted, and the molecular chains of the natural latex can be more dispersed, It can obtain wet masterbatch with uniform dispersion of carbon black, improve the dispersion of carbon black in rubber, and make the produced compound have better comprehensive performance, avoid the use of acid, reduce the generation of pollution and acidity The influence of residue on rubber properties achieves the goal of green environmental protection; it mixes the water dispersion of carbon black with the natural latex foamed with potassium oleate, the process is simple and environmentally friendly, and solves the problem of the high odor of the conventional acid flocculation process. , damage to equipment and unstable product quality.

Description of drawings:

Fig. 1 is a process flow block diagram of the present invention.

Detailed ways:

The present invention will be further described below through embodiments and in conjunction with the accompanying drawings.

Example 1:

The specific technological process of a carbon black/natural latex composite material preparation method involved in this example includes three steps of preparing carbon black aqueous solution, preparing potassium oleate aqueous solution and preparing carbon black/natural latex composite material:

(1) Preparation of carbon black aqueous solution: the granulated carbon black N115 is filtered and screened through an electric sieve of 100 mesh screen to obtain powder carbon black with a smaller particle size; 60 parts by mass of powder carbon black are mixed with deionized water A 25wt% carbon black aqueous solution was prepared, which was manually stirred with a stirring rod for a little while;

(2) preparation of potassium oleate aqueous solution: 1.5g potassium oleate is mixed with deionized water to make 10wt% potassium oleate aqueous solution, the potassium oleate aqueous solution is placed on the magnetic stirrer that rotating speed is 20rpm, and the temperature is 70 Stir for 30min under the condition of ℃;

(3) Preparation of carbon black/natural latex composite material:

The potassium oleate aqueous solution of 15g was mixed with 166.67 parts by mass of 60wt% NRL (natural latex), and a stirrer was used to carry out physical stirring and foaming treatment, and the stirring time was 5min, and the rotating speed was 1200r/min;

Mix the carbon black aqueous solution with the foamed NRL, and stir until flocculation to obtain carbon black masterbatch;

The carbon black masterbatch is compressed and dried, processed to a dry rubber level, and the drying temperature is 100° C. to obtain a carbon black/natural latex composite material that is foamed by containing potassium oleate.

Example 2:

This example involves the comprehensive performance test of carbon black/natural latex composite vulcanizate. The sizing material, the specific technological process is: mix carbon black/natural latex composite material with 1.06 parts by mass of stearic acid, 3.72 parts by mass of zinc oxide, 1.59 parts by mass of microcrystalline wax, 1.59 parts by mass of 4020 (anti-aging agent) and 1.59 parts by mass of 4020 RD (anti-aging agent) in mass parts was put into the internal mixer, and the temperature was 100 ° C and the rotation speed was 80 r/min for internal mixing to obtain a mixed rubber; 1.69 mass parts S (sulfur) and 1.28 mass parts NS ( Vulcanization accelerator) is mixed with the rubber compound on the open mill, and thin pass is carried out, wherein, the rolling and the triangle bag are each four times to obtain the rubber material;

The mechanical properties and dynamic mechanical properties of the three compounds were tested respectively, and the results are shown in the following table:

It can be seen from the above table that the T90 of the foaming flocculation method is significantly lower than that of the conventional dry method and stirring flocculation, thereby reducing the energy consumption; the tensile strength, elongation at break and tear strength are significantly improved, indicating that The carbon black/natural latex composite prepared by foaming flocculation method can effectively disperse the carbon black filler in the rubber matrix, improve the combination of carbon black and rubber molecular chain, so that the rubber compound forms more filler-rubber molecular chain The network structure leads to the densification of the cross-linked network structure and the improvement of the comprehensive performance; the Payne effect data shows that the carbon black/natural latex composite prepared by the foaming and flocculation method is beneficial to the dispersion of the filler in the colloid and its combination with the rubber; DIN abrasion data showed that the carbon black/natural latex composite prepared by foaming flocculation method had better filler dispersibility, more attachment points between filler and molecular chain, and better wear resistance.

Example 3:

A carbon black/natural latex composite material preparation method involved in this example selects granulated carbon black N235, and adopts the specific process of Example 1 to prepare the carbon black/natural latex composite material.

Example 4:

This example involves the comprehensive performance test of carbon black/natural latex composite vulcanizate. Sizing material, concrete technological process is identical with embodiment 1;

The mechanical properties and dynamic mechanical properties of the three compounds were tested respectively, and the results are shown in the following table:

Test items Tobacco Sheet Glue - Dry Process Agitation flocculation - wet process Foaming flocculation method - wet method T10 3.01 2.35 1.7 T90 6.95 6.65 5.53 ML 2.66 2.96 1.88 MH 19.34 18.62 16.84 Hardness (Shore A) 61.5 64 63 10% constant elongation (MPa) 0.82 0.88 0.91 100% constant elongation (MPa) 2.81 2.68 3.09 300% constant elongation (MPa) 13.99 12.95 14.64 Tensile strength (MPa) 23.83 22.60 25.25 Elongation at break(%) 480.77 435.03 520.69 Tensile product 11456.75 9831.68 13147.42 Payne 1007.95 867.92 802.88 DIN wear 0.1658 0.1616 0.1507 Carbon black dispersion 6 6.3 6.9

It can be seen from the above table that the MH-ML of the NR compound prepared by the foaming self-flocculation method is the largest and the processing performance is better, the MH-ML of the NR compound prepared by stirring flocculation is the second, and the NR prepared by the conventional dry method is the second. The MH-ML of the rubber compound is the worst and the processing performance is the worst;

The constant elongation, tensile strength, elongation at break and tensile product of the NR compound prepared by the foaming self-flocculation method are higher than those of the NR compound prepared by the conventional wet stirring flocculation and the conventional dry method, and the comprehensive performance is better. It is because the destructive effect of the foaming self-flocculation process on the rubber molecular chain is relatively small, which can effectively combine the carbon black with the rubber molecular chain, increase the reinforcing performance of the rubber compound, and form a stable filler-rubber molecular chain network structure. ;

The Payne of the NR compound prepared by the foaming self-flocculation method is the smallest, indicating that the dispersion of the filler and the combination of the rubber molecular chain are better, and the physical network structure of the filler and the filler is less, which is beneficial to improve the physical properties of the compound;

DIN abrasion data showed that the carbon black/natural latex composite prepared by foaming flocculation method had better filler dispersibility, more attachment points between filler and molecular chain, and better wear resistance.

Claims (4)

1. a carbon black natural rubber latex composite material preparation method, is characterized in that, it is a foaming self-flocculation method, and concrete technological process comprises preparing carbon black aqueous solution, preparing potassium oleate aqueous solution, preparing carbon black/natural latex composite material and a total of three step: (1) prepare carbon black aqueous solution: mix powder carbon black and deionized water to make 25wt% carbon black aqueous solution; (2) preparation of potassium oleate aqueous solution: potassium oleate and deionized water are mixed to make 10wt% potassium oleate aqueous solution, the potassium oleate aqueous solution is stirred, and potassium oleate is fully dissolved in deionized water and produces foam; (3) Preparation of carbon black/natural latex composite material: Mix the potassium oleate aqueous solution with 60wt% NRL, stir for 5min under the condition of a frequency of 10-20HZ, and foam; Mixing the carbon black aqueous solution with the foamed NRL, stirring until flocculation, to obtain a carbon black masterbatch; The carbon black masterbatch is compressed and dried, processed to a dry rubber level, and the drying temperature is 100° C. to obtain a carbon black/natural latex composite material that is foamed by containing potassium oleate. 2. carbon black natural rubber latex composite material preparation method according to claim 1, is characterized in that, the stirring process that step (2) relates to is that potassium oleate aqueous solution is placed on the magnetic stirrer that rotating speed is 20rpm, and temperature is 20rpm. Stir at 70°C for 30min. 3. The method for preparing carbon black natural rubber latex composite material according to claim 1 or 2, wherein the carbon black comprises N115, N234, cracked carbon black and other carbon black materials for making rubber products and tire industry. 4. The method for preparing carbon black natural rubber latex composite material according to claim 3, characterized in that, after the carbon black/natural latex composite material is put into an internal mixer, the temperature is 100 DEG C, and the rotating speed is carried out under the condition of 80 r/min. Mixed rubber can be obtained by mixing.

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