A method for preparing a natural latex / carbon black full-gel masterbatch

Abstract

The present application belongs to the technical field of rubber wet mixing, and particularly relates to a preparation method of natural latex / carbon black full-gel master batch, which combines the method of emulsion mixing and the gelation system without any chemical reagent. In the gelation stage, the carbon black and the natural latex mixed solution have no obvious phase separation, and no waste water is generated, realizing the green and environmental production purpose. The double-cone extruder is used for extruding and dehydrating, increasing the drying efficiency. The crushing of the double-cone extruder increases the drying area of the crushed rubber and the vacuum oven. The physical properties and dynamic mechanical properties of the mixed rubber prepared by the natural latex / carbon black full-gel master batch are significantly improved compared with the dry mixing rubber. The damage of the acid and other coagulants to the environment, equipment and workers is solved. The subsequent drying time of the natural latex / carbon black full-gel master batch is shortened. The preparation efficiency is improved, the performance of the rubber is improved, and the dispersion of the carbon black in the rubber matrix is improved in each stage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rubber wet mixing, and particularly relates to a preparation method of a natural latex / carbon black full-gel master batch. BACKGROUND

[0002] At present, in order to improve the dispersibility of fillers such as carbon black, with the successful application of wet mixing technology in the field of rubber industry, masterbatch is also applied in the field of rubber industry. In the wet mixing technology, the rubber coagulation generally adopts the way of adding acid coagulant, for example, the preparation method of zeolite rubber composite material disclosed in Chinese patent 201811575766.7 includes the following steps: (1) preparing raw materials according to mass fraction: NR 100; zinc oxide 3-5; stearic acid 1-3; antioxidant 4010NA 1; accelerator CZ 1-1.5; sulfur 2; zeolite powder 1-50; add zeolite powder into distilled water, stir uniformly, then mix with natural latex, and then mechanically stir uniformly, and stir with glass rod manually, while slowly adding acetic acid solution to make it coagulate; (2) the coagulation co-precipitate is pressed, washed, granulated, and finally dehydrated in an electric hot air oven and dried in a vacuum drying oven to constant weight, to obtain zeolite / NR wet co-precipitated rubber; (3) add antioxidants, accelerators, stearic acid, zinc oxide, zeolite and sulfur in turn on the open mill, mix uniformly by conventional mixing method, and obtain the mixed rubber; (4) measure the vulcanization time t of the mixed rubber by rubber vulcanization instrument, and vulcanize the mixed rubber after standing for 10-12 hours on the flat vulcanizing machine. The preparation method of wet mixing natural rubber material disclosed in Chinese patent 201110064299.3: A, the slurry is composed of white carbon black dry material, deionized water, coupling agent and surfactant, and the preparation procedure is: 1) soak 15%-40% white carbon black dry material in 60%-85% deionized water for 3-6 hours; 2) add 1%-10% coupling agent and 0.2%-5% surfactant of white carbon black dry material content, mechanically stir to mix white carbon black dry material, coupling agent and surfactant uniformly, and prepare white carbon black slurry; B, grind the above slurry with a grinder to white carbon black water dispersion with sedimentation less than 80 mg / h; C, prepare latex mixture 1) take field latex or centrifuged concentrated natural latex with dry rubber content of 15%-60%; 2) add prepared white carbon black water dispersion to the latex, stir for 20-50 minutes at room temperature; 3) mix the latex and white carbon black water dispersion uniformly to form latex mixture; D, coagulation, washing and dehydration 1) add 0.3%-1% acetic acid of the total amount of the mixture to the mixed solution after mixing uniformly, so that the pH value is 3-5, the latex is uniformly coagulated and co-precipitated with white carbon black; 2) wash off the excess acetic acid with water, and wash and dehydrate the coagulated rubber with a washing machine; 3) send the dehydrated rubber to a rubber granulator for granulation, then send the rubber particles to a box dryer for drying at a temperature of 90-120℃ for 4-6 hours; E, after drying completely, it is the mixed rubber material of natural rubber.A carbon black, synthetic rubber, and wet mixing rubber integrated production method disclosed in Chinese patent 201310095415.7 includes the following steps: (1) carbon black production: fuel oil or fuel gas is sent to the air provided by the main air blower and preheated to a certain temperature by the air preheater, mixed and combusted in the combustion section to generate high-temperature combustion gas flow; the raw material oil is preheated to a certain temperature by the preheater and then sprayed into the reaction furnace throat section to mix with the high-temperature combustion gas flow, rapidly cracking to produce carbon black flue gas; then, spray into the quenching water to reduce the flue gas temperature to terminate the reaction, and separate the carbon black after passing through the bag filter; (2) synthetic rubber production: monomers are polymerized in a solvent under the action of a catalyst to obtain a polymer, and then the catalyst is removed to obtain a synthetic rubber solution; (3) wet mixing rubber production: the carbon black obtained in step (1) is added to the synthetic rubber solution obtained in step (2), and a mixture is obtained by stirring, dispersing, and coagulating, and the mixture is dried after desolventizing to obtain the wet mixing rubber; wherein the heat generated during carbon black production and tail gas combustion is used to dry the wet mixing rubber. A synthetic rubber wet mixing process disclosed in Chinese patent 201811319015.9 includes the following steps: step S1, liquid preparation: synthetic rubber is placed in a container, white carbon black emulsion is added dropwise to the synthetic rubber at a stirring speed of 600 r / min, after the dropwise addition is completed, the emulsion is stirred at 1000 r / min for 30 min to mix the emulsion uniformly, the stirring speed is reduced to 800 r / min, and then amino sulfonic acid, accelerator NS, stearic acid, and antioxidant are sequentially added to the emulsion under stirring, after the addition is completed, the stirring is continued for 45-48 min to obtain a latex mixture; step S2, coagulation: the latex mixture coagulates on the inner wall of the mixing chamber; step S3, collection: the coagulated liquid flows out along the inner wall of the mixing chamber to collect a rubber mixture; step S4, stirring: the rubber mixture is stirred in a rubber wet mixer, the stirring process parameters are a stirring speed of 300-500 r / min and a stirring time of 3-8 min; step S5, drying: the stirred mixture is coagulated, washed, and desolventized to obtain a wet mixing synthetic rubber; the specific steps are as follows: the coagulated latex mixture is placed in a washing machine for desolventizing, and at the same time, the latex mixture is washed with tap water, the desolventized rubber sheet after the washing machine is placed in an oven at 75°C for drying for 7-8 h, the oven temperature is adjusted to 150°C, and the rubber sheet is dried for 110-115 s, then taken out, the dried rubber sheet is placed on an open mill for supplementary mixing, the rubber sheet is passed through the open mill rollers for ten times at the minimum gap of the open mill rollers to obtain a finished rubber, and the prepared rubber is vulcanized on a flat vulcanizing machine at 150°C and a pressure of 10 MPa for 15 min to obtain a synthetic rubber. This coagulation method with chemical reagents has hazards to the environment, equipment, and workers, and has an impact on the performance of the rubber, and there is a problem of long dehydration drying time of the water-containing rubber compound, which greatly wastes time cost and reduces the performance of the rubber.Therefore, the natural latex / carbon black full gel masterbatch preparation method is developed to solve the above problems, which has positive social and economic benefits. SUMMARY

[0003] The natural latex / carbon black full gel masterbatch preparation method is developed to solve the above problems, which has positive social and economic benefits.

[0004] To achieve the above purpose, the process of the natural latex / carbon black full gel masterbatch preparation method is as follows:

[0005] First, dry grinding of carbon black is carried out to prepare carbon black slurry;

[0006] Then, the carbon black slurry is added to the natural latex to prepare a mixed solution of carbon black attached to rubber particles;

[0007] Secondly, the gelation is carried out by mechanical force and thermal complexation without any chemical reagent to form a full gel;

[0008] Finally, the full gel is dehydrated, dried and granulated by a double-cone extruder to reduce the moisture content to the standard of dry rubber, and the natural latex / carbon black full gel masterbatch is obtained;

[0009] The specific process includes four steps of grinding, mixing, coagulation and drying:

[0010] (I) Grinding: The granulated carbon black is placed in a dry grinding device for dry grinding to prepare carbon black slurry;

[0011] The dry grinding device includes a ball mill and a bead mill supporting the dry grinding method; the mass percentage concentration of the carbon black slurry is 3-50%;

[0012] (II) Mixing: The carbon black slurry is poured into the natural latex at a set stirring speed to prepare a mixed solution of carbon black attached to rubber particles;

[0013] The stirring speed is 600 r / min; the mass percentage concentration of the natural latex is 60%;

[0014] (III) Coagulation: The mixed solution of carbon black attached to rubber particles is coagulated by stirring and heating to accelerate coagulation, and the coagulated rubber has no obvious phase separation; the coagulated precipitate is dried in a vacuum oven at a temperature of 60℃ to obtain a full gel;

[0015] The heating temperature is 100℃;

[0016] (iv) drying: the full gel is placed in an extruder to extrude and dehydrate, and after granulation and crushing, it is placed in a vacuum oven to dry, obtaining the natural latex / carbon black full gel masterbatch;

[0017] The extruder is a double-tapered extruder with a Y-type buffer extrusion mechanism, as shown in the figure. Figure 1 As shown in the figure, the Y-type buffer extrusion mechanism has a large compression ratio, the "V"-shaped part formed by the main screw and the auxiliary screw is responsible for material feeding, the "I"-shaped part of the main screw performs single-screw extrusion and dehydration, the extruder head is arranged at the tail of the extruder barrel to control the temperature during the extrusion process, the temperature control medium is heat conducting oil, the rotary knife granulating mechanism is connected with the extruder head to crush the extruded rubber, and the water extruded from the rubber flows out through the dehydration head arranged at the bottom of the extruder barrel.

[0018] The mass ratio of carbon black to natural latex involved in the present application is 3-6:10; in the extrusion and dehydration process, not only the rubber material is dehydrated, but also it is crushed and granulated, thereby improving the uniformity of the dispersion of carbon black in the rubber matrix.

[0019] Compared with the prior art, the present application combines the method of mixing emulsion and the gelation system without adding any chemical reagent. In the coagulation stage, the carbon black and natural latex mixed solution has no obvious phase separation, and no waste water is generated, achieving the purpose of green and environmental protection. The extrusion and dehydration by the double-tapered extruder increases the drying efficiency. The crushing by the double-tapered extruder increases the drying area of the crushed rubber and the vacuum oven. The physical properties and dynamic mechanical properties of the mixed rubber prepared from the natural latex / carbon black full gel masterbatch are significantly improved compared with the dry mixed rubber. The damage of the coagulant such as acid to the environment, equipment and workers is solved. The subsequent drying time of the natural latex / carbon black full gel masterbatch is shortened. The performance of the rubber material is improved while the preparation efficiency is improved. The dispersion of carbon black in the rubber matrix is improved in each stage, so that the natural latex / carbon black full gel masterbatch has excellent mechanical properties. The principle is scientific and reliable. Firstly, the carbon black is pretreated, and then the full gel is completed under the shearing force of the double-tapered extruder by the extrusion and dehydration method. It is environmentally friendly and has low rolling resistance. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of the structure and principle of the Y-type buffer extrusion mechanism involved in the present application.

[0021] Figure 2 The figure is a process flow diagram of Example 1 of the present application. DETAILED DESCRIPTION

[0022] The present application will be further described below by means of examples and in conjunction with the drawings.

[0023] Example 1

[0024] The specific process flow of the natural latex / carbon black full gel masterbatch preparation method involved in the embodiment includes four steps of grinding, mixing, coagulation and drying:

[0025] (I) Grinding: 70g of carbon black was placed in the grinding tank of a planetary ball mill for grinding for 0.5 hours, and 35g of carbon black was taken out to prepare a carbon black slurry with a mass percentage concentration of 25%, which was stirred uniformly and reserved for use;

[0026] (II) Mixing: The carbon black slurry was poured into 166.7g of natural latex with a mass percentage concentration of 60% under the condition that the stirring speed was 600r / min, to obtain a mixed solution in which carbon black was attached to rubber particles;

[0027] (III) Coagulation: The mixed solution in which carbon black was attached to rubber particles was coagulated by using a coagulation method, and after stirring at a stirring speed of 600r / min for 5 minutes, it was placed in an oil bath and heated to 100℃, and then taken out and stirred again at a stirring speed of 600r / min until a full gel was formed;

[0028] (IV) Drying: The full gel was placed in a double-tube extruder with a forced feeding function through the "V" type part composed of the main screw 1 and the auxiliary screw 2, the temperature of the extruder head 3 and the barrel 4 was heated to 110℃, the "I" type part of the main screw 1 was used to extrude and dehydrate the full gel by single screw, the extrusion granulating mechanism 5 was used for granulation and crushing to form crushed rubber, and the crushed rubber was placed in a vacuum oven with a temperature of 100℃ for drying for 15 minutes, so that the water content in the crushed rubber was reduced to 1%, and a natural latex / carbon black full gel masterbatch was obtained.

[0029] Example 2:

[0030] The embodiment relates to the comprehensive performance comparison of the dry mixing rubber and the wet mixing rubber.

[0031] 100g of natural rubber, 35g of carbon black, 5g of zinc oxide and 2g of stearic acid were sequentially added to an open mill for cold roll mixing for 8 minutes, 2.25g of sulfur and 0.7g of accelerator (TBBS) were added and passed through the open mill for 6 times, to obtain a dry mixing rubber;

[0032] 135g of the natural latex / carbon black full gel masterbatch prepared in Example 1, 5g of zinc oxide and 2g of stearic acid were placed in an open mill for cold roll mixing for 5 minutes, 2.25g of sulfur and 0.7g of accelerator (TBBS) were added and passed through the open mill for 6 times, to obtain a wet mixing rubber;

[0033] The dry mixing rubber and the wet mixing rubber were tested respectively, and the results are shown in the following table:

[0034]

[0035] It can be seen that the wet mixing rubber is superior to the dry mixing rubber in hardness, 10% set, 100% set, 300% set, tensile strength and elongation at break, and the DMA 60° loss factor of the wet mixing rubber is lower than that of the dry mixing rubber.

Claims

1. A process for the preparation of a natural latex / carbon black full-gel masterbatch, characterized in that, The process is as follows: First, dry grinding of carbon black is carried out to prepare carbon black slurry; Then, the carbon black slurry is added to the natural latex to prepare a mixed solution of carbon black attached to rubber particles; Secondly, the mixed solution is gelled by mechanical force and thermal complexation without any chemical reagent to form a full gel; Finally, the full gel is dehydrated, dried and granulated by a double-cone extruder to reduce the water content to the standard of dry rubber, thereby obtaining a natural latex / carbon black full gel masterbatch; The extruder is a double-cone extruder with a Y-type buffer extrusion mechanism. The "V" type part formed by the main screw 1 and the auxiliary screw of the Y-type buffer extrusion mechanism is responsible for material feeding. The "I" type part of the main screw 1 performs single screw extrusion dehydration. The extruder head is arranged at the tail of the extruder barrel to control the temperature of the extrusion process. The temperature control medium is heat conducting oil. The rotary knife granulating mechanism is connected with the extruder head to granulate and crush the extruded rubber. The water extruded from the rubber is discharged through the dehydration head arranged at the bottom of the extruder barrel.

2. The process for the preparation of natural latex / carbon black full coagulum masterbatch as claimed in claim 1 wherein, The specific process includes four steps of grinding, mixing, solidification and drying: (1) Grinding: The granulated carbon black is placed in a dry grinding device for dry grinding to prepare carbon black slurry; (2) Mixing: The carbon black slurry is poured into the natural latex at a set stirring speed to prepare a mixed solution of carbon black attached to rubber particles; (3) Solidification: The mixed solution of carbon black attached to rubber particles is gelled by stirring and heating to accelerate the gelling. The gelled rubber has no obvious phase separation. The gelled precipitate is placed in a vacuum oven at a temperature of 60℃ for drying to obtain a full gel; (4) Drying: The full gel is dehydrated by an extruder, and after granulation and crushing, it is dried in a vacuum oven to obtain a natural latex / carbon black full gel masterbatch.

3. The process for the preparation of natural latex / carbon black full coagulum masterbatch as claimed in claim 2 wherein, The specific process flow includes four steps of grinding, mixing, solidification and drying: (1) Grinding: 70g of carbon black is placed in the grinding tank of a planetary ball mill for grinding for 0.5 hours. 35g of carbon black is taken out to prepare a carbon black slurry with a mass percentage concentration of 25%. Stir until uniform for standby; (2) Mixing: The carbon black slurry is poured into 166.7g of natural latex with a mass percentage concentration of 60% under the condition of stirring speed of 600r / min to obtain a mixed solution of carbon black attached to rubber particles; (3) Solidification: The mixed solution of carbon black attached to rubber particles is gelled by stirring at a stirring speed of 600r / min for 5 minutes. Then, it is placed in an oil bath and heated to 100℃. After taking out, it is stirred again at a stirring speed of 600r / min until a full gel is formed; (4) Drying: The full gel is placed in a double-cone extruder with forced feeding function through the "V" type part formed by the main screw and the auxiliary screw. The temperature of the extruder head and the barrel is heated to 110℃. The "I" type part of the main screw performs single screw extrusion dehydration on the full gel. The extrusion granulating mechanism performs granulation and crushing to form crushed rubber. The crushed rubber is placed in a vacuum oven at a temperature of 100℃ for drying for 15 minutes to reduce the water content in the crushed rubber to 1%, thereby obtaining a natural latex / carbon black full gel masterbatch.

4. The process for the preparation of natural latex / carbon black full coagulum masterbatch as claimed in claim 3 wherein, The dry grinding equipment in step (1) includes a ball mill and a bead mill supporting the dry grinding method; the mass percentage concentration of the carbon black slurry is 3-50%.

5. The process for the preparation of natural latex / carbon black full coagulum masterbatch as claimed in claim 3 wherein, The stirring speed in step (2) is 600 r / min; the mass percentage concentration of the natural latex is 60%.

6. The process for the preparation of natural latex / carbon black full coagulum masterbatch as claimed in claim 3 wherein, The heating temperature in step (3) is 100℃.

7. The process for the preparation of natural latex / carbon black all-gel masterbatch according to claim 1 or 2, characterized in that, The mass ratio of the carbon black to the natural latex is 3-6:10.

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