Liquid-phase in-situ modified natural rubber and preparation method thereof

Abstract

The invention relates to the field of new materials, and particularly discloses liquid-phase in-situ modified natural rubber and a preparation method thereof. The liquid-phase in-situ modified natural rubber comprises the following raw materials in parts by weight: natural rubber; high molecular weight polyisobutylene; a compatilizer; polyvinyl alcohol; lauryl sodium sulfate; borax; casein; white carbon black; sodium dodecyl benzene sulfonate; polysorbate; a silicon ore suspending agent; a silane coupling agent; a rubber defoaming agent; formic acid; aluminum fluoride nanoparticles; and hydroxypropyl methyl cellulose. The preparation method comprises the following steps: preparing a white carbon black aqueous dispersion; preparing a rubber compound latex mixed solution; and curing and post-processing. The liquid-phase in-situ modified natural rubber has the advantages of excellent processability and capability of reducing production energy consumption.

Description

Technical Field

[0001] The present application relates to the field of new materials, and more specifically, to a liquid phase in-situ modified natural rubber and a preparation method thereof. Background Art

[0002] Natural rubber is a natural polymer extracted from the bark of the rubber tree. It is mainly composed of cis-1,4-polyisoprene, which gives natural rubber unique physical and chemical properties, making it an indispensable and important material in industry and daily life.

[0003] The rubber compound of tires is generally made by adding reinforcing agents and other additives to natural rubber after plasticization by dry mixing, and then vulcanizing to form products. Silica is a very useful reinforcing agent. Dry mixing of silica can improve the wear resistance and other physical and mechanical properties of tires. The amount needs to exceed 30 parts to have a significant performance improvement effect.

[0004] However, the increase in the amount of white carbon black leads to increased water absorption and uneven dispersion, resulting in poor processing performance of the compound rubber and high energy consumption during the production process. Summary of the invention

[0005] In order to improve the dispersibility of white carbon black in a rubber mix, enhance the processability of the rubber mix, and thus reduce production energy consumption, the present application provides a liquid phase in-situ modified natural rubber and a preparation method thereof.

[0006] In a first aspect, the present application provides a liquid phase in-situ modified natural rubber and a preparation method thereof, which adopts the following technical scheme:

[0007] A liquid phase in-situ modified natural rubber comprises the following raw materials in parts by weight:

[0008] 70 parts of natural rubber

[0009] 30 parts of high molecular weight polyisobutylene

[0010] 1-2 parts of compatibilizer

[0011] Polyvinyl alcohol 3-5 parts

[0012] 1.6-2.4 parts of sodium lauryl sulfate

[0013] Borax 0.005-0.007 parts

[0014] Casein 0.24-0.36 parts

[0015] 30-45 parts of white carbon black

[0016] Sodium dodecylbenzene sulfonate 0.3-0.45 parts

[0017] Polysorbate 0.3-0.45 parts

[0018] Silicon ore suspension agent 0.06-0.2 parts

[0019] Silane coupling agent 1.8-2.7 parts

[0020] Rubber defoamer 0.5-1 part

[0021] Formic acid 0.4-0.6 parts

[0022] 4-6 parts of aluminum fluoride nanoparticles

[0023] Hydroxypropyl methylcellulose 2-3 parts.

[0024] By adopting the above technical solution, aluminum fluoride nanoparticles have excellent hydrophobicity. After surface treatment, white carbon black forms a water dispersion, and aluminum fluoride nanoparticles can bond and adsorb with white carbon black, improve the water absorption characteristics of white carbon black, and coat the white carbon black particles to form a hydrophobic film, making it easy to disperse. Hydroxypropyl methylcellulose can help maintain the uniform dispersion of white carbon black and aluminum fluoride nanoparticles in natural rubber and high molecular weight polyisobutylene, prevent sedimentation or stratification, and change the fluidity of the rubber during mixing. The addition of high molecular weight polyisobutylene can form a tiny, discontinuous filler network inside the rubber matrix, so that the white carbon black adsorbed with aluminum fluoride nanoparticles is evenly dispersed in this filler network, and is more closely connected to the rubber matrix, which helps to improve the Mooney viscosity of natural rubber, improve its fluidity, and improve the processability of the mixed rubber, thereby reducing production energy consumption.

[0025] Optionally, the silicon ore suspending agent is sodium lignin sulfonate.

[0026] Optionally, the silane coupling agent is silicon-69.

[0027] Optionally, the compatibilizer is maleic anhydride grafted polyisobutylene.

[0028] Optionally, the rubber defoamer is polydimethylsiloxane.

[0029] Optionally, the modified natural rubber further comprises 2-4 parts of composite fiber, the composite fiber comprises corn protein and wheat protein, and the weight ratio of corn protein to wheat protein is 1:1.

[0030] By adopting the above technical solution, the composite fiber made of corn protein fiber and wheat protein fiber can adjust the humidity of the matrix material, further improve the dispersibility of white carbon black, and enhance the processability, elasticity, tensile strength and thermal stability of the compound rubber.

[0031] Optionally, the corn protein and wheat protein are blended and spun into composite fibers through solution spinning.

[0032] In a second aspect, the present application provides a method for preparing liquid phase in-situ modified natural rubber, which adopts the following technical solution:

[0033] A method for preparing liquid phase in-situ modified natural rubber comprises the following steps:

[0034] (1) Preparation of white carbon black aqueous dispersion:

[0035] Weigh white carbon black, dissolve it in deionized water, the weight ratio of white carbon black to deionized water is 1:2, then add sodium dodecylbenzene sulfonate, polysorbate, silica ore suspension agent and silane coupling agent in sequence, stir and mix until uniform, and prepare white carbon black slurry; grind the white carbon black slurry until the sedimentation volume of the white carbon black slurry is less than 50 mg / h, and prepare a white carbon black water dispersion;

[0036] (2) Preparation of rubber latex mixture:

[0037] Preparation of natural rubber latex mixture:

[0038] Preparation of natural rubber latex: crush and dry natural rubber to obtain natural rubber powder for later use; dissolve polyvinyl alcohol and sodium lauryl sulfate in deionized water, stir evenly to form a stable emulsifier solution with a mass concentration of 3%, wherein the amount of polyvinyl alcohol is half of the total amount, and the amount of sodium lauryl sulfate is half of the total amount; add the natural rubber powder to the emulsifier solution, homogenize at room temperature to completely disperse the natural rubber powder, then adjust the pH to neutral, filter out impurities, and obtain natural rubber latex;

[0039] Preparation of high molecular weight polyisobutylene latex: dissolving high molecular weight polyisobutylene in hexane for later use; dissolving polyvinyl alcohol and sodium lauryl sulfate in deionized water, stirring evenly to form a stable emulsifier solution with a mass concentration of 3%, wherein the amount of polyvinyl alcohol is half of the total amount, and the amount of sodium lauryl sulfate is half of the total amount; adding the dissolved high molecular weight polyisobutylene to the emulsifier solution, homogenizing at room temperature to completely disperse the high molecular weight polyisobutylene; evaporating to remove the hexane; adjusting the pH to neutral, filtering impurities, and obtaining the high molecular weight polyisobutylene latex;

[0040] Latex mixing: heating natural rubber latex and high molecular weight polyisobutylene latex to 40° C. respectively, gradually adding polyisobutylene latex to natural rubber latex while stirring at room temperature, homogenizing, adding compatibilizer, mixing evenly, and obtaining mixed latex;

[0041] Prepare casein solution: add borax to deionized water and stir to dissolve, prepare boric acid solution with a mass concentration of 10%; add casein to deionized water and stir to dissolve, the mass concentration is 10%, then add boric acid solution and stir evenly;

[0042] Add casein solution, white carbon black aqueous dispersion, aluminum fluoride nanoparticles, hydroxypropyl methylcellulose and rubber defoamer to the mixed latex in sequence, stirring each time after adding a raw material until it is evenly dispersed before adding the next one, until all the raw materials are completely evenly dispersed, to obtain a mixed rubber latex mixture;

[0043] (3) Curing and post-processing:

[0044] Take formic acid and dissolve it in deionized water to prepare a formic acid solution with a mass concentration of 10%, add the formic acid solution with a mass concentration of 10% to the mixed rubber latex mixture, stir until it is evenly dispersed, adjust the pH, and evenly flocculate the latex and co-precipitate with white carbon black for 8-16 hours; wash the excess formic acid from the coagulated rubber with clean water, wash the rubber and dehydrate it; granulate the dehydrated rubber, wash the rubber again until the pH is neutral, and obtain rubber particles; dry the rubber particles at 90-110°C for 4-6 hours until they are completely dried, so as to obtain liquid phase in-situ modified natural rubber.

[0045] By adopting the above technical scheme, the natural rubber is modified by the liquid phase in-situ method, so that the dispersion and uniformity of white carbon black in the rubber are greatly improved, the production energy consumption is reduced, the dust is reduced, and the environment is improved.

[0046] In a third aspect, the present application provides a method for preparing liquid phase in-situ modified natural rubber, which adopts the following technical solution:

[0047] A method for preparing liquid phase in-situ modified natural rubber comprises the following steps:

[0048] (1) Preparation of white carbon black aqueous dispersion:

[0049] Weigh white carbon black, dissolve it in deionized water, the weight ratio of white carbon black to deionized water is 1:2, then add sodium dodecylbenzene sulfonate, polysorbate, silica ore suspension agent and silane coupling agent in sequence, stir and mix until uniform, and prepare white carbon black slurry; grind the white carbon black slurry until the sedimentation volume of the white carbon black slurry is less than 50 mg / h, and prepare a white carbon black water dispersion;

[0050] (2) Preparation of rubber latex mixture:

[0051] Preparation of natural rubber latex mixture:

[0052] Preparation of natural rubber latex: crush and dry natural rubber to obtain natural rubber powder for later use; dissolve polyvinyl alcohol and sodium lauryl sulfate in deionized water, stir evenly to form a stable emulsifier solution with a mass concentration of 3%, wherein the amount of polyvinyl alcohol is half of the total amount, and the amount of sodium lauryl sulfate is half of the total amount; add the natural rubber powder to the emulsifier solution, homogenize at room temperature to completely disperse the natural rubber powder, then adjust the pH to neutral, filter out impurities, and obtain natural rubber latex;

[0053] Preparation of high molecular weight polyisobutylene latex: dissolving high molecular weight polyisobutylene in hexane for later use; dissolving polyvinyl alcohol and sodium lauryl sulfate in deionized water, stirring evenly to form a stable emulsifier solution with a mass concentration of 3%, wherein the amount of polyvinyl alcohol is half of the total amount, and the amount of sodium lauryl sulfate is half of the total amount; adding the dissolved high molecular weight polyisobutylene to the emulsifier solution, homogenizing at room temperature to completely disperse the high molecular weight polyisobutylene; evaporating to remove the hexane; adjusting the pH to neutral, filtering impurities, and obtaining the high molecular weight polyisobutylene latex;

[0054] Latex mixing: heating natural rubber latex and high molecular weight polyisobutylene latex to 40° C. respectively, gradually adding polyisobutylene latex to natural rubber latex while stirring at room temperature, homogenizing, adding compatibilizer, mixing evenly, and obtaining mixed latex;

[0055] Prepare casein solution: add borax to deionized water and stir to dissolve, prepare boric acid solution with a mass concentration of 10%; add casein to deionized water and stir to dissolve, the mass concentration is 10%, then add boric acid solution and stir evenly;

[0056] Add casein solution, white carbon black aqueous dispersion, aluminum fluoride nanoparticles, hydroxypropyl methylcellulose, composite fiber and rubber defoamer to the mixed latex in sequence, stirring each time after adding a raw material until it is evenly dispersed before adding the next one, until all the raw materials are completely evenly dispersed, to obtain a mixed rubber latex mixture;

[0057] (3) Curing and post-processing:

[0058] Take formic acid and dissolve it in deionized water to prepare a formic acid solution with a mass concentration of 10%, add the formic acid solution with a mass concentration of 10% to the mixed rubber latex mixture, stir until it is evenly dispersed, adjust the pH, and evenly flocculate the latex and co-precipitate with white carbon black for 8-16 hours; wash the excess formic acid from the coagulated rubber with clean water, wash the rubber and dehydrate it; granulate the dehydrated rubber, wash the rubber again until the pH is neutral, and obtain rubber particles; dry the rubber particles at 90-110°C for 4-6 hours until they are completely dried, so as to obtain liquid phase in-situ modified natural rubber.

[0059] In summary, this application has the following beneficial effects:

[0060] 1. In the present application, high molecular weight polyisobutylene is preferably used in combination with natural rubber, aluminum fluoride nanoparticles are added to improve the hydrophobicity of white carbon black, and hydroxypropyl methylcellulose is added to improve the dispersibility of white carbon black and aluminum fluoride nanoparticles in the rubber matrix, which can effectively improve the processability of the mixed rubber, reduce production energy consumption, and greatly improve the mechanical properties of the manufactured vulcanized rubber, such as tensile strength and tear strength.

[0061] 2. Since the present application uses composite fibers, the humidity of the matrix material is adjusted, the dispersibility of white carbon black is further improved, and the processability, elasticity, tensile strength and thermal stability of the mixed rubber are enhanced.

[0062] 3. The method of the present application modifies natural rubber by a liquid phase in-situ method, so that the dispersibility and uniformity of white carbon black in the rubber are greatly improved, production energy consumption is reduced, dust is reduced, and the environment is improved. DETAILED DESCRIPTION

[0063] The present application is further described in detail with reference to the following examples. It is specially noted that if no specific conditions are specified in the following examples, the conventional conditions or the conditions recommended by the manufacturer are followed, and the raw materials used in the following examples can be obtained from common commercial sources unless otherwise specified.

[0064] Natural rubber, produced in Hainan Island.

[0065] High molecular weight polyisobutylene, model HM-50, viscosity average molecular weight 390000-490000.

[0066] Maleic anhydride grafted polyisobutylene, brand MA2400.

[0067] Borax, analytical grade AR, content 99.5%.

[0068] Casein, brand - Nanshi, CAS number is 9000-71-9.

[0069] White carbon black is precipitated white carbon black with a purity of 95%.

[0070] Formic acid, commercially available 85 wt% formic acid.

[0071] Aluminum fluoride nanoparticles, analytical grade, content 99%, first grade.

[0072] Hydroxypropyl methylcellulose, CAS number is 9004-65-3.

[0073] Corn protein, CAS number is 9010-66-6.

[0074] Wheat protein, CAS number is 9007-90-3.

[0075] Example

[0076] Example 1

[0077] A liquid phase in-situ modified natural rubber comprises the following raw materials: 70 kg of natural rubber; 30 kg of high molecular weight polyisobutylene; 1 kg of a compatibilizer, which is maleic anhydride grafted polyisobutylene; 3 kg of polyvinyl alcohol; 1.6 kg of sodium dodecyl sulfate; 0.005 kg of borax; 0.24 kg of casein; 30 kg of white carbon black; 0.3 kg of sodium dodecylbenzene sulfonate; 0.3 kg of polysorbate; 0.06 kg of a silica ore suspension agent, which is sodium lignin sulfonate; 1.8 kg of a silane coupling agent, which is silicon-69; 0.5 kg of a rubber defoamer, which is polydimethylsiloxane; 0.4 kg of formic acid; 4 kg of aluminum fluoride nanoparticles; and 2 kg of hydroxypropyl methylcellulose.

[0078] A method for preparing liquid phase in-situ modified natural rubber comprises the following steps:

[0079] Weigh each raw material according to the above formula and set aside.

[0080] (1) Preparation of white carbon black aqueous dispersion:

[0081] Weigh white carbon black and dissolve it in deionized water, the weight ratio of white carbon black to deionized water is 1:2, then add sodium dodecylbenzene sulfonate, polysorbate, silica ore suspension agent and silane coupling agent in sequence, stir and mix until uniform, and prepare white carbon black slurry. Grind the white carbon black slurry at 800r / min on a high-speed shear disperser until the sedimentation volume of the white carbon black slurry is less than 50mg / h, and prepare a white carbon black aqueous dispersion.

[0082] (2) Preparation of rubber latex mixture:

[0083] Preparation of natural rubber latex mixture:

[0084] Preparation of natural rubber latex: crush and dry natural rubber to micron level to obtain natural rubber powder for later use. Dissolve polyvinyl alcohol and sodium dodecyl sulfate in deionized water and stir evenly to form a stable emulsifier solution with a mass concentration of 3%. The amount of polyvinyl alcohol is half of the total amount, and the amount of sodium dodecyl sulfate is half of the total amount. Add the natural rubber powder to the emulsifier solution, homogenize at room temperature, pressure 100MPa, single homogenization time 30min, cycle number 6 times, make the natural rubber powder completely dispersed, then adjust the pH to neutral, use a 0.45μm microporous filter membrane to filter impurities, vacuum defoam, and obtain natural rubber latex.

[0085] Preparation of high molecular weight polyisobutylene latex: dissolve high molecular weight polyisobutylene in hexane and set aside. Dissolve polyvinyl alcohol and sodium dodecyl sulfate in deionized water and stir evenly to form a stable emulsifier solution with a mass concentration of 3%. The amount of polyvinyl alcohol is half of the total amount, and the amount of sodium dodecyl sulfate is half of the total amount. Add the dissolved high molecular weight polyisobutylene to the emulsifier solution, homogenize at room temperature, pressure 100 MPa, single homogenization time 30 minutes, cycle number 6 times, so that the high molecular weight polyisobutylene is completely dispersed. Evaporate to remove hexane; adjust the pH to neutral, use a 0.45μm microporous filter membrane to filter impurities, vacuum defoam, and obtain high molecular weight polyisobutylene latex.

[0086] Latex mixing: Heat natural rubber latex and high molecular weight polyisobutylene latex to 40°C respectively, gradually add polyisobutylene latex to natural rubber latex while stirring at room temperature, homogenize, homogenize at room temperature, pressure 100MPa, single homogenization time 30min, cycle number 5 times. Add compatibilizer, stir until mixed evenly, filter impurities with 0.45μm microporous filter membrane, vacuum defoam, and obtain mixed latex.

[0087] Prepare casein solution: Add borax to deionized water and stir to dissolve, prepare a 10% boric acid solution. Add casein to deionized water and stir to dissolve, the mass concentration is 10%, then add 10% boric acid solution, stir evenly, and prepare casein solution.

[0088] Add casein solution, white carbon black aqueous dispersion, aluminum fluoride nanoparticles, hydroxypropyl methylcellulose and rubber defoamer to the mixed latex in sequence. After adding one raw material each time, stir until it is evenly dispersed before adding the next one. Stir at room temperature at a speed of 800r / min until all the raw materials are completely dispersed and there is no foam, so as to obtain a mixed rubber latex mixture.

[0089] (3) Curing and post-processing:

[0090] Dissolve formic acid in deionized water to prepare a 10% formic acid solution. Add a 10% formic acid solution to the mixed rubber latex mixture, stir at 1000r / min for 10 minutes at room temperature until it is evenly dispersed, and adjust the pH. The latex is uniformly flocculated and co-precipitated with white carbon black for 8 hours. The coagulated rubber is repeatedly rolled with a rubber washer, and the excess formic acid is washed with clean water, and the rubber is washed and dehydrated with a rubber washer. The dehydrated rubber is granulated at the micron level and then washed in a rubber washing pool until the pH is neutral to obtain rubber particles. Dry the rubber particles at 90°C for 6 hours until they are completely dried to obtain liquid-phase in-situ modified natural rubber.

[0091] Example 2

[0092] A liquid phase in-situ modified natural rubber. The difference between this embodiment and embodiment 1 is that the amounts of various raw materials are different, see Table 1 for details.

[0093] A method for preparing liquid phase in-situ modified natural rubber. The difference between this embodiment and embodiment 1 is that (3) during the curing and post-treatment, the time for latex flocculation and co-precipitation with white carbon black is 12 hours; and the drying conditions of the rubber particles are 100°C for 5 hours.

[0094] Example 3

[0095] A liquid phase in-situ modified natural rubber. The difference between this embodiment and embodiment 1 is that the amounts of various raw materials are different, see Table 1 for details.

[0096] A method for preparing liquid phase in-situ modified natural rubber. The difference between this embodiment and embodiment 1 is that (3) during the curing and post-treatment, the time for latex flocculation and co-precipitation with white carbon black is 16 hours; the drying conditions of the rubber particles are 110°C for 4 hours.

[0097] Example 4

[0098] A liquid phase in-situ modified natural rubber. The difference between this embodiment and embodiment 2 is that the modified natural rubber in this embodiment also includes 2kg of composite fiber, the composite fiber includes corn protein and wheat protein, and the weight ratio of corn protein to wheat protein is 1:1.

[0099] A method for preparing liquid phase in-situ modified natural rubber comprises the following steps:

[0100] Weigh each raw material according to the above formula and set aside.

[0101] (1) Preparation of white carbon black aqueous dispersion:

[0102] Weigh white carbon black and dissolve it in deionized water, the weight ratio of white carbon black to deionized water is 1:2, then add sodium dodecylbenzene sulfonate, polysorbate, silica ore suspension agent and silane coupling agent in sequence, stir and mix until uniform, and prepare white carbon black slurry. Grind the white carbon black slurry at 800r / min on a high-speed shear disperser until the sedimentation volume of the white carbon black slurry is less than 50mg / h, and prepare a white carbon black aqueous dispersion.

[0103] (2) Preparation of rubber latex mixture:

[0104] Preparation of natural rubber latex mixture:

[0105] Preparation of natural rubber latex: crush and dry natural rubber to micron level to obtain natural rubber powder for later use. Dissolve polyvinyl alcohol and sodium dodecyl sulfate in deionized water and stir evenly to form a stable emulsifier solution with a mass concentration of 3%. The amount of polyvinyl alcohol is half of the total amount, and the amount of sodium dodecyl sulfate is half of the total amount. Add the natural rubber powder to the emulsifier solution, homogenize at room temperature, pressure 100MPa, single homogenization time 30min, cycle number 6 times, make the natural rubber powder completely dispersed, then adjust the pH to neutral, use a 0.45μm microporous filter membrane to filter impurities, vacuum defoam, and obtain natural rubber latex.

[0106] Preparation of high molecular weight polyisobutylene latex: dissolve high molecular weight polyisobutylene in hexane and set aside. Dissolve polyvinyl alcohol and sodium dodecyl sulfate in deionized water and stir evenly to form a stable emulsifier solution with a mass concentration of 3%. The amount of polyvinyl alcohol is half of the total amount, and the amount of sodium dodecyl sulfate is half of the total amount. Add the dissolved high molecular weight polyisobutylene to the emulsifier solution, homogenize at room temperature, pressure 100 MPa, single homogenization time 30 minutes, cycle number 6 times, so that the high molecular weight polyisobutylene is completely dispersed. Evaporate to remove hexane; adjust the pH to neutral, use a 0.45μm microporous filter membrane to filter impurities, vacuum defoam, and obtain high molecular weight polyisobutylene latex.

[0107] Latex mixing: Heat natural rubber latex and high molecular weight polyisobutylene latex to 40°C respectively, gradually add polyisobutylene latex to natural rubber latex while stirring at room temperature, homogenize, homogenize at room temperature, pressure 100MPa, single homogenization time 30min, cycle number 5 times. Add compatibilizer, stir until mixed evenly, filter impurities with 0.45μm microporous filter membrane, vacuum defoam, and obtain mixed latex.

[0108] Prepare casein solution: Add borax to deionized water and stir to dissolve, prepare a 10% boric acid solution. Add casein to deionized water and stir to dissolve, the mass concentration is 10%, then add 10% boric acid solution, stir evenly, and prepare casein solution.

[0109] Preparation of composite fiber: Take 5kg corn protein, 5kg wheat protein, 1kg glycerol, 0.1kg glutaraldehyde, 0.2kg polyvinyl alcohol and 0.05kg ascorbic acid, dissolve in 50%wt formic acid solution, stir at 500r / min for 2h at room temperature until completely dissolved to form a protein solution. Use acetic acid to adjust the pH of the protein solution to 5. Homogenize at 50℃ and 80MPa, and homogenize three times, each homogenization time is 15min. The homogenized protein solution is vacuum degassed for 30min and filtered with a 0.45μm microporous filter membrane. Prepare an aqueous solution containing 10wt% calcium chloride and 1wt% acetic acid as a coagulation bath, control the temperature at 25℃, extrude the protein solution into the coagulation bath through a spinneret, control the pressure of the spinneret to 2bar, the speed to 15m / min, and the temperature of the coagulation bath to form primary fibers. Wash the primary fibers with deionized water to remove the coagulant and other impurities remaining on the surface. The cleaned fiber is dried in an oven at 40°C to ensure that its water content is less than 5wt%. The fiber is stretched at 4 times. The stretched fiber is placed in a constant temperature environment for shaping at 80°C for 1 hour to ensure that its size is stable. The diameter of the composite fiber is controlled at 10μm, the fineness is 2μm, and the length is 30mm. The composite fiber can be obtained and the required amount is taken according to the ratio.

[0110] Add casein solution, white carbon black aqueous dispersion, aluminum fluoride nanoparticles, hydroxypropyl methylcellulose, composite fiber and rubber defoamer to the mixed latex in sequence. After adding one raw material each time, stir until it is evenly dispersed before adding the next one. Stir at room temperature at a speed of 800r / min until all the raw materials are completely dispersed and there is no foam, so as to obtain a mixed rubber latex mixture.

[0111] (3) Curing and post-processing:

[0112] Dissolve formic acid in deionized water to prepare a 10% formic acid solution. Add a 10% formic acid solution to the mixed rubber latex mixture, stir at 1000r / min for 10 minutes at room temperature until it is evenly dispersed, and adjust the pH. The latex is uniformly flocculated and co-precipitated with white carbon black for 12 hours. The coagulated rubber is repeatedly rolled with a rubber washer, and the excess formic acid is washed with clean water, and the rubber is washed and dehydrated with a rubber washer. The dehydrated rubber is granulated at the micron level and then washed in a rubber washing pool until the pH is neutral to obtain rubber particles. Dry the rubber particles at 100°C for 5 hours until they are completely dried to obtain liquid-phase in-situ modified natural rubber.

[0113] Example 5

[0114] The difference between this embodiment and embodiment 4 is that the amount of composite fiber used is different, see Table 1 for details.

[0115] Example 6

[0116] The difference between this embodiment and embodiment 4 is that the amount of composite fiber used is different, see Table 1 for details.

[0117] Example 7

[0118] The difference between this embodiment and embodiment 5 is that all corn protein is replaced by an equal amount of wheat protein in the composite fiber.

[0119] Example 8

[0120] The difference between this embodiment and embodiment 5 is that all the wheat proteins are replaced by an equal amount of corn protein in the composite fiber.

[0121] Comparative Example

[0122] Comparative Example 1

[0123] A dry-process modified natural rubber comprises 100 kg of natural rubber and 38 kg of white carbon black.

[0124] A preparation method of dry modified natural rubber comprises the following steps: using a two-roll open mill to plasticize a natural rubber sheet at 50°C, gradually adding white carbon black, and mixing for 30 minutes until the white carbon black is completely and evenly distributed, taking out the mixed rubber sheet, cooling it to room temperature with water, and thus obtaining the dry modified natural rubber.

[0125] Comparative Example 2

[0126] The difference between this comparative example and Example 2 is that in this comparative example, all high molecular weight polyisobutylene is replaced by an equal amount of natural rubber, and there is no high molecular weight polyisobutylene, aluminum fluoride nanoparticles and hydroxypropyl methylcellulose in the formula.

[0127] Comparative Example 3

[0128] The difference between this comparative example and Example 2 is that in this comparative example, all high molecular weight polyisobutylene is replaced by an equal amount of natural rubber, and there is no high molecular weight polyisobutylene in the formula.

[0129] Comparative Example 4

[0130] The difference between this comparative example and Example 2 is that there are no aluminum fluoride nanoparticles in this comparative example.

[0131] Comparative Example 5

[0132] The difference between this comparative example and Example 2 is that there is no hydroxypropyl methylcellulose in this comparative example.

[0133] Comparative Example 6

[0134] The difference between this comparative example and Example 2 is that in this comparative example, all high molecular weight polyisobutylene is replaced by an equal amount of natural rubber, and there is no high molecular weight polyisobutylene and aluminum fluoride nanoparticles in the formula.

[0135] Comparative Example 7

[0136] The difference between this comparative example and Example 2 is that in this comparative example, all high molecular weight polyisobutylene is replaced by an equal amount of natural rubber, and there is no high molecular weight polyisobutylene and hydroxypropyl methylcellulose in the formula.

[0137] Comparative Example 8

[0138] The difference between this comparative example and Example 2 is that there are no aluminum fluoride nanoparticles and hydroxypropyl methylcellulose in this comparative example.

[0139] Table 1 Amount of each raw material in each embodiment and comparative example

[0140]

[0141]

[0142]

[0143] Performance testing

[0144] Test methods

[0145] 1. Unvulcanized rubber

[0146] Referring to "GB / T1232.1-2016 Determination of Unvulcanized Rubber by Disc Shear Viscometer Part 1: Determination of Mooney Viscosity", the modified natural rubber prepared in each embodiment and comparative example was sampled and tested to obtain the Mooney viscosity value. Three samples were tested for each embodiment or comparative example and the average value was taken. The test results are shown in Table 2.

[0147] Referring to "GB / T 3510-2023 Rapid plasticity test method for determination of plasticity of unvulcanized rubber", the modified natural rubber prepared in each embodiment and comparative example was sampled and tested, and the plasticity value was measured. Three samples were tested for each embodiment or comparative example and the median value was taken. The test results are shown in Table 2.

[0148] 2. Vulcanized rubber

[0149] Take the modified natural rubber obtained in each embodiment and comparative example, and prepare the corresponding vulcanized rubber according to the following formula and vulcanization conditions: 150kg of modified natural rubber, 45kg of N375 carbon black, 5kg of zinc oxide, 1.5kg of stearic acid, 1.5kg of antioxidant RD, 1.5kg of antioxidant 4020, 1.5kg of accelerator NS, and 2kg of sulfur powder; the vulcanization conditions are 151°C and 30min.

[0150] With reference to "GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", samples were prepared for the vulcanized rubbers prepared in different embodiments and comparative examples. The samples were dumbbell-shaped type 1. The tensile strength, elongation at break and 300% tensile stress of each sample were tested. Three samples of the vulcanized rubber corresponding to each embodiment or comparative example were tested and the average value was taken. The test results are shown in Table 2.

[0151] With reference to "GB / T 529-2008 Determination of tear strength of vulcanized rubber or thermoplastic rubber", samples were prepared for the vulcanized rubbers prepared in different embodiments and comparative examples. The samples were rectangular and notched. The tear strength of each sample was measured. Three samples of the vulcanized rubber corresponding to each embodiment or comparative example were tested and the average value was taken. The test results are shown in Table 2.

[0152] With reference to "GB / T 1689-2014 Determination of wear resistance of vulcanized rubber (using Akron abrasion tester)", samples of the vulcanized rubbers prepared in different embodiments and comparative examples were prepared, and the sample wear volume of each sample was measured. Three samples of the vulcanized rubber corresponding to each embodiment or comparative example were tested and the average value was taken. The test results are shown in Table 2.

[0153] Table 2 Test results

[0154]

[0155]

[0156] It can be seen from Example 2 and Comparative Example 1 and Table 2 that the liquid phase in-situ modified natural rubber of the present application has excellent processability, can reduce production energy consumption, and the prepared vulcanized rubber also has excellent mechanical properties.

[0157] Combining Example 2 and Comparative Examples 2-8 with Table 2, it can be seen that the use of high molecular weight polyisobutylene and natural rubber, the addition of aluminum fluoride nanoparticles to improve the hydrophobicity of white carbon black, and the addition of hydroxypropyl methylcellulose to improve the dispersibility of white carbon black and aluminum fluoride nanoparticles in the rubber matrix can effectively improve the processability of the mixed rubber, reduce production energy consumption, and greatly improve the mechanical properties of the manufactured vulcanized rubber, such as tensile strength and tear strength. Moreover, when the three are used in combination, the performance improvement effect is optimal.

[0158] Combining Example 2 and Example 5 with Table 2, it can be seen that the addition of the composite fiber further enhances the processability of the liquid phase in-situ modified natural rubber and the mechanical properties of the corresponding vulcanized rubber. Combining Example 2, Example 5, Example 7, Example 8 with Table 2, it can be seen that when the composite fiber is made of wheat protein and corn protein, the performance improvement effect is optimal when they are coordinated.

[0159] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A liquid phase in-situ modified natural rubber, characterized in that: The invention comprises the following raw materials in parts by weight: 70 parts of natural rubber 30 parts of high molecular weight polyisobutylene 1-2 parts of compatibilizer Polyvinyl alcohol 3-5 parts 1.6-2.4 parts of sodium lauryl sulfate Borax 0.005-0.007 parts Casein 0.24-0.36 parts 30-45 parts of white carbon black Sodium dodecylbenzene sulfonate 0.3-0.45 parts Polysorbate 0.3-0.45 parts Silicon ore suspension agent 0.06-0.2 parts Silane coupling agent 1.8-2.7 parts Rubber defoamer 0.5-1 part Formic acid 0.4-0.6 parts 4-6 parts of aluminum fluoride nanoparticles Hydroxypropyl methylcellulose 2-3 parts.

2. The liquid phase in-situ modified natural rubber according to claim 1, characterized in that: The silicon ore suspending agent is sodium lignin sulfonate.

3. The liquid phase in-situ modified natural rubber according to claim 1, characterized in that: The silane coupling agent is silicon-69.

4. The liquid phase in-situ modified natural rubber according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted polyisobutylene.

5. The liquid phase in-situ modified natural rubber according to claim 1, characterized in that: The rubber defoamer is polydimethylsiloxane.

6. The liquid phase in-situ modified natural rubber according to claim 1, characterized in that: The modified natural rubber also includes 2-4 parts of composite fiber, which includes corn protein and wheat protein, and the weight ratio of corn protein to wheat protein is 1:

1.

7. The liquid phase in-situ modified natural rubber according to claim 6, characterized in that: The corn protein and wheat protein are blended and spun through solution to prepare composite fiber.

8. A method for preparing liquid phase in-situ modified natural rubber according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Preparation of white carbon black aqueous dispersion: Weigh white carbon black, dissolve it in deionized water, the weight ratio of white carbon black to deionized water is 1:2, then add sodium dodecylbenzene sulfonate, polysorbate, silica ore suspension agent and silane coupling agent in sequence, stir and mix until uniform, and prepare white carbon black slurry; grind the white carbon black slurry until the sedimentation volume of the white carbon black slurry is less than 50 mg / h, and prepare a white carbon black water dispersion; (2) Preparation of rubber latex mixture: Preparation of natural rubber latex mixture: Preparation of natural rubber latex: crush and dry natural rubber to obtain natural rubber powder for later use; dissolve polyvinyl alcohol and sodium lauryl sulfate in deionized water, stir evenly to form a stable emulsifier solution with a mass concentration of 3%, wherein the amount of polyvinyl alcohol is half of the total amount, and the amount of sodium lauryl sulfate is half of the total amount; add the natural rubber powder to the emulsifier solution, homogenize at room temperature to completely disperse the natural rubber powder, then adjust the pH to neutral, filter out impurities, and obtain natural rubber latex; Preparation of high molecular weight polyisobutylene latex: dissolving high molecular weight polyisobutylene in hexane for later use; dissolving polyvinyl alcohol and sodium lauryl sulfate in deionized water, stirring evenly to form a stable emulsifier solution with a mass concentration of 3%, wherein the amount of polyvinyl alcohol is half of the total amount, and the amount of sodium lauryl sulfate is half of the total amount; adding the dissolved high molecular weight polyisobutylene to the emulsifier solution, homogenizing at room temperature to completely disperse the high molecular weight polyisobutylene; evaporating to remove the hexane; adjusting the pH to neutral, filtering impurities, and obtaining the high molecular weight polyisobutylene latex; Latex mixing: heating natural rubber latex and high molecular weight polyisobutylene latex to 40° C. respectively, gradually adding polyisobutylene latex to natural rubber latex while stirring at room temperature, homogenizing, adding compatibilizer, mixing evenly, and obtaining mixed latex; Prepare casein solution: add borax to deionized water and stir to dissolve, prepare boric acid solution with a mass concentration of 10%; add casein to deionized water and stir to dissolve, the mass concentration is 10%, then add boric acid solution and stir evenly; Add casein solution, white carbon black aqueous dispersion, aluminum fluoride nanoparticles, hydroxypropyl methylcellulose and rubber defoamer to the mixed latex in sequence, stirring each time after adding a raw material until it is evenly dispersed before adding the next one, until all the raw materials are completely evenly dispersed, to obtain a mixed rubber latex mixture; (3) Curing and post-processing: Take formic acid and dissolve it in deionized water to prepare a formic acid solution with a mass concentration of 10%, add the formic acid solution with a mass concentration of 10% to the mixed rubber latex mixture, stir until it is evenly dispersed, adjust the pH, and evenly flocculate the latex and co-precipitate with white carbon black for 8-16 hours; wash the excess formic acid from the coagulated rubber with clean water, wash the rubber and dehydrate it; granulate the dehydrated rubber, wash the rubber again until the pH is neutral, and obtain rubber particles; dry the rubber particles at 90-110°C for 4-6 hours until they are completely dried, so as to obtain liquid phase in-situ modified natural rubber.

9. A method for preparing liquid phase in-situ modified natural rubber according to any one of claims 6-7, characterized in that: The following steps are involved: (1) Preparation of white carbon black aqueous dispersion: Weigh white carbon black, dissolve it in deionized water, the weight ratio of white carbon black to deionized water is 1:2, then add sodium dodecylbenzene sulfonate, polysorbate, silica ore suspension agent and silane coupling agent in sequence, stir and mix until uniform, and prepare white carbon black slurry; grind the white carbon black slurry until the sedimentation volume of the white carbon black slurry is less than 50 mg / h, and prepare a white carbon black water dispersion; (2) Preparation of rubber latex mixture: Preparation of natural rubber latex mixture: Preparation of natural rubber latex: crush and dry natural rubber to obtain natural rubber powder for later use; dissolve polyvinyl alcohol and sodium lauryl sulfate in deionized water, stir evenly to form a stable emulsifier solution with a mass concentration of 3%, wherein the amount of polyvinyl alcohol is half of the total amount, and the amount of sodium lauryl sulfate is half of the total amount; add the natural rubber powder to the emulsifier solution, homogenize at room temperature to completely disperse the natural rubber powder, then adjust the pH to neutral, filter out impurities, and obtain natural rubber latex; Preparation of high molecular weight polyisobutylene latex: dissolving high molecular weight polyisobutylene in hexane for later use; dissolving polyvinyl alcohol and sodium lauryl sulfate in deionized water, stirring evenly to form a stable emulsifier solution with a mass concentration of 3%, wherein the amount of polyvinyl alcohol is half of the total amount, and the amount of sodium lauryl sulfate is half of the total amount; adding the dissolved high molecular weight polyisobutylene to the emulsifier solution, homogenizing at room temperature to completely disperse the high molecular weight polyisobutylene; evaporating to remove the hexane; adjusting the pH to neutral, filtering impurities, and obtaining the high molecular weight polyisobutylene latex; Latex mixing: heating natural rubber latex and high molecular weight polyisobutylene latex to 40° C. respectively, gradually adding polyisobutylene latex to natural rubber latex while stirring at room temperature, homogenizing, adding compatibilizer, mixing evenly, and obtaining mixed latex; Prepare casein solution: add borax to deionized water and stir to dissolve, prepare boric acid solution with a mass concentration of 10%; add casein to deionized water and stir to dissolve, the mass concentration is 10%, then add boric acid solution and stir evenly; Add casein solution, white carbon black aqueous dispersion, aluminum fluoride nanoparticles, hydroxypropyl methylcellulose, composite fiber and rubber defoamer to the mixed latex in sequence, stirring each time after adding a raw material until it is evenly dispersed before adding the next one, until all the raw materials are completely evenly dispersed, to obtain a mixed rubber latex mixture; (3) Curing and post-processing: Take formic acid and dissolve it in deionized water to prepare a formic acid solution with a mass concentration of 10%, add the formic acid solution with a mass concentration of 10% to the mixed rubber latex mixture, stir until it is evenly dispersed, adjust the pH, and evenly flocculate the latex and co-precipitate with white carbon black for 8-16 hours; wash the excess formic acid from the coagulated rubber with clean water, wash the rubber and dehydrate it; granulate the dehydrated rubber, wash the rubber again until the pH is neutral, and obtain rubber particles; dry the rubber particles at 90-110°C for 4-6 hours until they are completely dried, so as to obtain liquid phase in-situ modified natural rubber.

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