High-dispersion nano silicon dioxide, preparation method thereof and rubber composite material

Abstract

The invention relates to high-dispersion nano silicon dioxide, a preparation method thereof and a rubber composite material, and the preparation method comprises the following steps: hydrated nano silicon dioxide, an aqueous medium and arginine are subjected to sanding treatment, active sites are generated on the surface of the hydrated nano silicon dioxide, and the hydrated nano silicon dioxide is obtained; the arginine, the active sites and surface hydroxyl groups of the hydrated nano-silica are subjected to a grafting reaction in the sanding treatment process to form modified mixed slurry, a predetermined amount of a silane coupling agent is added, the silane coupling agent is grafted to the surface of the hydrated nano-silica, the slurry is subjected to solid-liquid separation, washing, drying and grinding into powder, and the high-dispersion nano-silica is obtained. The grafting efficiency and the powder dispersity are remarkably improved, the obtained nano silicon dioxide has high dispersity, the specific surface area is remarkably increased, the oil absorption value is reduced, high filling can be achieved when the nano silicon dioxide is applied to the rubber composite material, the tensile strength and the elongation at break of the rubber composite material are greatly improved, and meanwhile the raw material cost is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rubber additives, and particularly relates to high-dispersed nano-silica, a preparation method thereof, and a rubber composite material. BACKGROUND

[0002] Nano-silica has been widely used in the fields of coatings, plastics, medical carriers, daily chemical products, etc. due to its large specific surface area, good biological safety, and high reactivity. In particular in the field of rubber, nano-silica has been used as the best inorganic material to replace carbon black. However, due to a large number of hydroxyl groups on the surface of nano-silica, the nano-silica has weak acidity and hydrophilicity, which makes it difficult to disperse in the preparation process of the composite material, and the nano-silica has poor compatibility with the matrix material, and is prone to form "particle aggregation" in the matrix of the composite material, thereby affecting the filling effect and limiting the application of the nano-silica. Therefore, the modification of nano-silica has become a hot topic.

[0003] At present, the surface of nano-silica is mainly grafted with small molecule modifiers through chemical modification to reduce the hydroxyl groups on the surface of nano-silica. At the same time, the grafted small molecules are inserted into the crosslinking center in the crosslinking process of the matrix, so as to enhance the dispersibility and compatibility of nano-silica in the matrix. In addition, some molecular chains similar to the chain segments of the matrix polymer are grafted on the surface of nano-silica through chemical grafting, which can more effectively promote the dispersion of nano-silica in the matrix polymer.

[0004] In the prior art, TESPT (bis-(3-(triethoxysilyl)propyl)-tetrasulfide) is used to perform dehydration condensation reaction with the hydroxyl groups on the surface of nano-silica to realize the chemical bonding between TESPT and nano-silica. In a solution with a certain alcohol-water ratio, TESPT is first hydrolyzed under weak acid conditions, and then nano-silica is grafted at 50 DEG C. After washing and drying, the nano-silica is compounded with a rubber matrix. The results show that the nano-silica modified by TESPT can form a chemical bond in the compounding process with the rubber, and the stability of the nano-silica in the compounding process with the rubber is improved.

[0005] Generally, the traditional modification method usually has harsh reaction conditions, needs organic solvents for dissolution, has a large amount of addition, has a complicated preparation process, requires active groups on the surface, has a low grafting rate, and has technical problems such as difficulty in large-scale production.

[0006] In summary, it is urgent to provide high-dispersed nano-silica with high dispersibility and large specific surface area, and a preparation method thereof, and a rubber composite material with better compatibility in the compounding process with a matrix and a preparation method thereof, which have excellent product performance and outstanding economy. SUMMARY

[0007] The application aims to provide a high-dispersible nano-silica with a large specific surface area and better compatibility in the process of being compounded with a matrix, a preparation method of the high-dispersible nano-silica, and a rubber composite material with excellent product performance and outstanding economy and a preparation method of the rubber composite material.

[0008] The above object is achieved by the following technical solution: a preparation method of high-dispersible nano-silica, comprising the following steps: S1, modification: mixing hydrated nano-silica, an aqueous medium and arginine in a predetermined ratio to form a mixed slurry, and performing sand milling treatment on the mixed slurry, so as to generate active sites on the surface of the hydrated nano-silica through high-energy grinding, and the arginine and the active sites and the surface hydroxyl groups of the hydrated nano-silica are grafted to form a modified mixed slurry in the sand milling treatment process; S2, silane coupling agent grafting: adding a predetermined amount of a silane coupling agent to the modified mixed slurry, and grafting the silane coupling agent on the surface of the hydrated nano-silica; S3, post-treatment: performing solid-liquid separation on the slurry treated in step S2, and washing, drying and grinding the slurry into powder to obtain the high-dispersible nano-silica.

[0009] The arginine is used for surface activation treatment of the nano-silica in the application by means of sand milling, so that the size of the inorganic particles is reduced, and the key is that high-activity active sites are created on the surface of the nano-silica in the high-energy sand milling process. The nature of the active sites is defect sites, which are vacancies or coordination unsaturated sites formed after the surface atoms are acted on by mechanical force. These sites have a high-activity window period of short existence, which can enable the arginine to rapidly react with the active sites. The arginine is added before the sand milling treatment, and the active sites with short existence can be rapidly captured in the high-energy sand milling process. The active sites can immediately react with the surrounding arginine molecules to realize a grafting efficiency and a grafting density much higher than those of the traditional method.

[0010] The arginine is not only grafted with the surface hydroxyl groups of the nano-silica, but also grafted with the "active sites" on the surface of the nano-silica, has a high grafting rate, and can make the surface grafting of the nano-silica more sufficient. Experiments prove that the grafting of the arginine effectively activates the surface and creates more superior conditions for the subsequent grafting of the silane coupling agent. The possible mechanism is that the arginine molecular chain provides better steric hindrance, and the specific functional groups of the arginine can produce certain intermolecular interactions with the silane coupling agent, guide and promote the directional arrangement and grafting of the silane coupling agent on the surface.

[0011] The nano-silicon dioxide modified by arginine is grafted with a silane coupling agent, which effectively increases the steric hindrance effect between the nano-silicon dioxide particles, so that the nano-particles have better dispersibility, and high-dispersibility nano-silicon dioxide can be prepared. The prepared nano-silicon dioxide has improved surface hydrophobicity and more uniform adhesion to the high polymer matrix material.

[0012] The specific surface area of the prepared nano-silicon dioxide is increased, the oil absorption value is reduced, the dispersibility and the compatibility with the high polymer matrix are significantly improved, and the technical problems of traditional modification processes, such as complexity and poor dispersibility, can be effectively solved.

[0013] It should be noted that the aqueous medium herein refers to a liquid medium with water as the main component and continuous phase, which is used for dispersing the nano-silicon dioxide particles and as a carrier for the reaction. The content of water is usually not less than 50%, preferably not less than 80%, and more preferably 100% based on the total weight of the aqueous medium, i.e. pure water. The aqueous medium can be specifically selected from deionized water, pure water, distilled water, or water and one or more water-soluble organic solvents. From the perspectives of environmental protection and cost, pure water is preferred.

[0014] In the present application, arginine which is water-soluble and non-toxic is first used to activate the surface of silicon dioxide, then a silane coupling agent is grafted, and at the same time, sand milling is used to reduce the particle size of the inorganic particles during the grafting process, so that the grafted nano-silicon dioxide has good dispersibility and large specific surface area, thereby improving the compatibility during the subsequent compounding process of nano-silicon dioxide and the matrix.

[0015] As a preferred further technical solution, in step S2, the silane coupling agent is directly added to the grinding mechanism treated in step S1, and the sand milling treatment is continued for a predetermined time to complete the grafting of the silane coupling agent.

[0016] In this way, the modification in step S1 and the grafting of the silane coupling agent in step S2 are both carried out in the same grinding mechanism and during the grinding process, that is, the modification and the grafting of the silane coupling agent are both completed in a continuous sand milling process. The stepwise sand milling allows the arginine to fully activate the surface hydroxyl groups of the silicon dioxide, and then a more stable interface layer is formed through the grafting of the vinyl triethoxysilane, thereby avoiding the competitive reaction between the modifiers and further improving the grafting rate.

[0017] As a preferred further technical solution, in step S1, the mass ratio of the hydrated nano-silicon dioxide, the aqueous medium and the arginine is 150:350:4-5.

[0018] As a preferred further technical solution, the silane coupling agent is vinyl triethoxysilane.

[0019] Vinyl triethoxysilane can be grafted with the surface hydroxyl and active sites of nano-silica, enhance the chemical bonding with rubber matrix, and improve the mechanical properties of the composite. The silane coupling agent uses vinyl triethoxysilane as the preferred embodiment, and of course, as those skilled in the art should know, other silane coupling agents can be used to graft to nano-silica and play the same role, but the effect is different.

[0020] As preferred, the further technical solution is that the mass ratio of the arginine to the silane coupling agent is 4-5:1-2.

[0021] As preferred, the further technical solution is that the sanding treatment time of the step S1 is 1-1.5 hours, the sanding treatment time of the step S2 is 3-4 hours, and the rotation speed of the sanding treatment is 2500-3000 r / min. The appropriate rotation speed ensures that the sanding energy is sufficient to produce active sites, while avoiding excessive fragmentation.

[0022] As preferred, the further technical solution is that the specific steps of the step S3 include: centrifugal separation of the slurry, the rotation speed of the centrifugal separation is 9000-12000 r / min, and the centrifugal time is 5-6 min; washing 3-4 times, and then drying at 120-150℃ for 20-24h, grinding into powder after drying, the grinding rotation speed is 500-600 r / min, the grinding time is 8-12 min, and the powder is obtained by passing through an 80 mesh screen after grinding.

[0023] To achieve the above purpose, the application further provides a high-dispersion nano-silica prepared by the preparation method of the high-dispersion nano-silica. The nano-silica has a high specific surface area, a low oil absorption value, and excellent dispersibility, and is suitable for various high polymer composites.

[0024] To achieve the above purpose, the application further provides a rubber composite material, the raw materials of which include the high-dispersion nano-silica.

[0025] After the nano-silica is modified by arginine and then grafted with vinyl triethoxysilane, the steric hindrance effect between the nano-silica particles is effectively increased, so that the nano-particles have better dispersibility. Meanwhile, the grafted vinyl triethoxysilane can better disperse the nano-particles in the rubber matrix, has good compatibility with the rubber matrix, and can better penetrate the rubber system during the rubber vulcanization process, so that the nano-silica can be uniformly distributed in the rubber "space network structure", and the performance (such as tensile strength and elongation at break) of the rubber composite material is improved.

[0026] As preferred, the further technical solution is that the adding amount of the high-dispersed nanometer silicon dioxide is 45-55% based on the total weight of the rubber. The high filling amount of the high-dispersed nanometer silicon dioxide of the application can significantly reduce the cost while maintaining or improving the mechanical properties of the product, and enhance the competitiveness of the product.

[0027] To achieve the above-mentioned purpose, the application further provides a preparation method of the rubber composite material, which comprises the following steps: Banbury mixing: Banbury mixing and dispersing the rubber matrix; Modification: adding the high-dispersed nanometer silicon dioxide into the rubber matrix and continuing to Banbury mixing and dispersing to prepare a rubber composite; Vulcanization: vulcanizing the rubber composite.

[0028] The high-dispersed nanometer silicon dioxide of the application is uniformly dispersed in the Banbury mixing and vulcanization processes, the nanoparticles have better dispersibility, and after being grafted with vinyl triethoxysilane, the nanoparticles can be better dispersed in the rubber matrix, have good compatibility with the rubber matrix, and can be better interpenetrated in the rubber system in the rubber vulcanization process, so that the nanometer silicon dioxide can be uniformly distributed in the "spatial network structure" of the rubber, and the performance of the composite material is optimized. Experiments show that: by high filling (50%) of the high-dispersed nanometer silicon dioxide, combined with optimized Banbury mixing and vulcanization processes, the silicon dioxide is uniformly distributed in the "spatial network structure" of the rubber; the tensile strength of the rubber composite material is above 625 MPa (the highest is 741 MPa), which is much higher than the performance of the commercially available silicon dioxide with an adding amount of 40% (500 MPa), and the rubber amount is significantly reduced, and the cost is reduced by about 7000 yuan per ton, thereby solving the contradiction between the high filling performance and the poor performance of the traditional rubber composite.

[0029] Compared with the prior art, the powder specific surface area of the high-dispersed nanometer silicon dioxide prepared by the application is significantly increased (up to 229.17 m² / g), the oil absorption value is greatly reduced (the reduction is nearly 49%), and the high-dispersed nanometer silicon dioxide exhibits excellent dispersibility and compatibility in the rubber matrix; after the high-dispersed nanometer silicon dioxide is applied to the butadiene rubber / styrene butadiene rubber system at a high filling amount of 50%, the tensile strength of the composite material is as high as 741 MPa, and the elongation at break is more than 320%.

[0030] The process of the application is simple, environmentally friendly, has high grafting efficiency, and is suitable for large-scale production; while significantly improving the mechanical properties of the rubber product, the raw material cost is effectively reduced due to the high filling amount, and the product has excellent performance and outstanding economy. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments illustrated in the drawings, and their specification, are included to explain the application and are not meant to limit the application.

[0032] Figure 1 is a schematic diagram of the diluted and uniformly mixed suspension of nanosilica prepared in the examples and comparative examples of the present application; Figure 2 is a schematic diagram of the diluted and uniformly mixed suspension of nanosilica prepared in the examples and comparative examples of the present application after 72h of sedimentation. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor shall fall within the protection scope of the present application.

[0034] In addition, the technical solutions in the various embodiments of the present application can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize the combination. When the combination of technical solutions appears to be contradictory or unachievable, it shall be considered that the combination of technical solutions does not exist and is not within the protection scope required by the present application.

[0035] Unless otherwise specified, the drugs / reagents used are commercially available.

[0036] A preparation method of high-dispersion nanosilica, comprising the following steps: S1, modification: mixing hydrated nanosilica, an aqueous medium and arginine in a predetermined ratio to form a mixed slurry, and performing sand milling treatment on the mixed slurry, so as to generate active sites on the surface of the hydrated nanosilica by high-energy grinding, and the arginine and the active sites and the surface hydroxyl groups of the hydrated nanosilica undergo grafting reaction to form a modified mixed slurry during the sand milling treatment; S2, silane coupling agent grafting: adding a predetermined amount of silane coupling agent into the modified mixed slurry, and grafting the silane coupling agent on the surface of the hydrated nanosilica; S3, post-treatment: performing solid-liquid separation on the slurry treated in step S2, and washing, drying and grinding into powder to obtain high-dispersion nanosilica.

[0037] It should be noted that the aqueous medium herein refers to a liquid medium with water as the main component and continuous phase, which is used for dispersing the nanosilica particles and as a carrier for reaction. The content of water is usually not less than 50%, preferably not less than 80%, and more preferably 100% based on the total weight of the aqueous medium, i.e. pure water. The aqueous medium can be specifically selected from deionized water, pure water, distilled water, or water and one or more water-soluble organic solvents. From the perspectives of environmental protection and cost, pure water is preferred.

[0038] On the basis of the above-mentioned embodiments, in another embodiment of the present application, the silane coupling agent is directly added into the grinding mechanism treated in step S1 in step S2, and the sanding treatment is continued for a predetermined time to complete the grafting of the silane coupling agent.

[0039] On the basis of the above-mentioned embodiments, in another embodiment of the present application, in step S1, the mass ratio of the hydrated nanosilica, the aqueous medium and arginine is 150:350:4-5.

[0040] On the basis of the above-mentioned embodiments, in another embodiment of the present application, the silane coupling agent is vinyltriethoxysilane.

[0041] On the basis of the above-mentioned embodiments, in another embodiment of the present application, the mass ratio of arginine to the silane coupling agent is 4-5:1-2.

[0042] On the basis of the above-mentioned embodiments, in another embodiment of the present application, the sanding treatment in step S1 is performed for 1-1.5 hours, the sanding treatment in step S2 is performed for 3-4 hours, and the rotation speed of the sanding treatment is 2500-3000 r / min. The appropriate rotation speed ensures that the sanding energy is sufficient to generate active sites, while avoiding excessive fragmentation.

[0043] On the basis of the above-mentioned embodiments, in another embodiment of the present application, the specific steps of step S3 include: centrifuging the slurry at a rotation speed of 9000-12000 r / min for 5-6 min; washing 3-4 times, and then drying at 120-150℃ for 20-24 h, grinding into powder after drying at a rotation speed of 500-600 r / min for 8-12 min, and passing through an 80-mesh screen to obtain high-dispersion nanosilica.

[0044] The present application also provides a high-dispersion nanosilica prepared by any of the above-mentioned preparation methods of high-dispersion nanosilica. The nanosilica has a high specific surface area, a low oil absorption value and excellent dispersibility, and is suitable for various polymer composites.

[0045] The present application also provides a rubber composite material, the raw materials of which include the high-dispersion nanosilica.

[0046] On the basis of the above-mentioned embodiments, in another embodiment of the present application, the addition amount of the high-dispersion nanosilica is 45-55% based on the total weight of the rubber. The high filling amount of the high-dispersion nanosilica of the present application can significantly reduce the cost, while maintaining or improving the mechanical properties of the product, and enhancing the competitiveness of the product.

[0047] The present invention also provides a method for preparing the rubber composite material, the embodiment of which is as follows, including the following steps: Internal mixing: the process of internally mixing and dispersing the rubber matrix; Modification: The highly dispersed nano-silica is added to the rubber matrix and further mixed and dispersed to prepare a rubber composite; Vulcanization: The process of vulcanizing a rubber compound.

[0048] To better understand the technical solution of the present invention, specific embodiments are provided as follows: Sand milling equipment: 1L vertical sand mill; grinding media: 0.2mm zirconia beads; dispersion media: pure water; centrifuge; forced-air drying oven; Example 1 of preparation of highly dispersed nano silica The preparation of highly dispersed nano-silica in this embodiment includes the following steps: 150g of hydrated nano-silica (commercially available, 20nm particle size), 350g of water, and 4.5g of arginine (modifier) ​​were ground in a vertical sand mill at 2800 rpm for 1 hour. Then, 1.5g of vinyltriethoxysilane (VTES, molecular formula C8H18O3Si, molecular weight approximately 190.32) was added, and grinding continued for 3 hours. The resulting slurry was then centrifuged at 10000 rpm for 6 minutes, washed 3-4 times, dried in an oven at 150℃ for 24 hours, and then ground into powder in a ball mill at 500-600 rpm for 8-12 minutes. The powder was then sieved through an 80-mesh sieve. This sample was marked as test sample number 5.

[0049] Comparative Example 1 The preparation of nano-silica includes the following steps: 150g of hydrated nano-silica (commercially available, 20nm particle size), 350g of water, 1.5g of modifier (vinyltriethoxysilane), and 2ml of glacial acetic acid were ground in a vertical sand mill at 2800 rpm for 4 hours. The ground slurry was then centrifuged, washed three times, and dried in an oven at 150℃ for 24 hours. It was then ground in a ball mill at 500-600 rpm for 8-12 minutes until powdered. The powder was then sieved through an 80-mesh sieve. This sample was marked as test sample number 1.

[0050] Comparative Example 2 The preparation of nano-silica includes the following steps: Hydrated nano-silica (commercially available particle size 20 nm) 150 g, water 350 g, modifier: polyvinyl pyrrolidone (K30) 3 g were ground in a vertical sand mill, grinding speed setting 2800 r / min, grinding time: 4 h, the ground slurry was taken out, centrifuged at 10000 r / min for 6 min, washed 3-4 times, then placed in an oven, dried at 150°C for 24 h, ground in a ball mill at a speed of 500-600 r / min for 8-12 min to obtain a powder, and sieved through a 80 mesh screen. Marked as No. 2 test sample.

[0051] Comparative Example 3 Preparation of nano-silica, including the following steps: Hydrated nano-silica (commercially available particle size 20 nm) 150 g, water 350 g, modifier: polyethylene glycol (PEG400) 6 g were ground in a vertical sand mill, grinding speed setting 2800 r / min, grinding time: 4 h, the ground slurry was taken out, centrifuged at 10000 r / min for 6 min, washed 3-4 times, then placed in an oven, dried at 150°C for 24 h, ground in a ball mill at a speed of 500-600 r / min for 8-12 min to obtain a powder, and sieved through a 80 mesh screen. Marked as No. 3 test sample.

[0052] Comparative Example 4 Preparation of nano-silica, including the following steps: Hydrated nano-silica (commercially available particle size 20 nm) 150 g, water 350 g, modifier: arginine 4.5 g were ground in a vertical sand mill, grinding speed setting 2800 r / min, grinding time: 4 h, the ground slurry was taken out, centrifuged at 10000 r / min for 6 min, washed 3-4 times, then placed in an oven, dried at 150°C for 24 h, ground in a ball mill at a speed of 500 r / min for 12 min to obtain a powder, and sieved through a 80 mesh screen. Marked as No. 4 test sample.

[0053] Comparative Example 5 Preparation of nano-silica, without adding any modifier and silane coupling agent, other processing steps same as in Example 1 of preparation of highly dispersed nano-silica. Marked as No. 6 test sample.

[0054] Example 1 Figure 1 The silica suspension samples prepared in Example 1 and each comparative example were tested. Each sample was taken out and diluted to a mass concentration of 1%, then transferred into a centrifuge tube, and observed after standing for 72 h. The results are shown in Table 1. Figure 1 Figure 2 ​The display: without adding modifier (sample No. 6), adding vinyl triethoxysilane (sample No. 1) and adding polyvinylpyrrolidone (sample No. 2) have no obvious effect on the suspension and dispersion of nanosilica, the dispersion effect of nanosilica added with polyethylene glycol (sample No. 3) is not as good as that of arginine (sample No. 4) and arginine compounded with vinyl triethoxysilane (sample No. 5), wherein the suspension and dispersion effect of the nanosilica prepared by arginine compounded with vinyl triethoxysilane (sample No. 5) is the best. This may be due to the fact that the nanosilica is modified by arginine and then grafted with vinyl triethoxysilane, which effectively increases the steric hindrance effect between the nanosilica particles, so that the nanoparticles have better dispersibility, and the grafted vinyl triethoxysilane can better disperse the nanoparticles in the matrix.

[0055] The prepared sample No. 4, sample No. 5 and sample No. 6 are further subjected to performance test, and the test results are as follows: after being modified by arginine, the specific surface area of the sample No. 4 is obviously increased, the specific surface area is increased from 185 g / m 2 to 204.74 g / m 2 , which is increased by 10.67% compared with sample No. 6; the oil absorption value is reduced from 2.35 g / 100 g to 1.22 g / 100 g, which is reduced by 48.08% compared with sample No. 6; and the specific surface area of the nanosilica in sample No. 5 is increased to 229.17 g / m 2 after being modified by arginine and vinyl triethoxysilane, which is increased by 23.87% compared with sample No. 6; the oil absorption value is reduced to 1.20 g / 100 g, which is reduced by 48.93% compared with sample No. 6.

[0056] It is shown that the prepared high-dispersion silica powder has improved hydrophobicity and better adhesion to the high-molecular matrix material.

[0057] Preparation example 1 of rubber composite material The rubber composite material is prepared by the following steps: Banbury mixing: 700 g of butadiene rubber (brand 0150) and 300 g of styrene-butadiene rubber (brand RC2564S) are weighed and added to a Banbury mixer for dispersion, and the Banbury mixing temperature is set to 60 DEG C, and the dispersion time is 5 min in forward rotation and 5 min in reverse rotation; Modification: Add 1 kg of high dispersion silica prepared in Example 1, continue to disperse in the internal mixer, heat to 100℃, continue to disperse for 10 min forward rotation and 10 min reverse rotation, add insoluble sulfur 20g IS-90, and anti-sulfur reducing agent 50g HVA-2, set the temperature of the internal mixer to 100℃, rotate for 2 min forward and 2 min reverse, then raise the protective cover of the internal mixer, heat to 150℃, rotate for 6 min forward and 6 min reverse, then take out the rubber compound after mixing, cool and place for 24 h; Vulcanization: Take out the rubber and place it in a mold 10 cm, use a flat plate vulcanizer to vulcanize it, set the vulcanization temperature to 105℃ for the first stage, 5 min, 160℃ for the second stage, 5 min, 175℃ for the third stage, 6 min, 180℃ for the fourth stage, 6 min, and 200℃ for the fifth stage, 8 min, set the pressure to 16t, after vulcanization, take out the vulcanized rubber, then cut it into a rectangular strip, measure its thickness, length and width with a vernier caliper, and then place it in a universal tensile testing machine for mechanical property testing.

[0058] Preparation of rubber composite material Example 2 Preparation of high dispersion nano-silica: Hydrated nano-silica (15 nm) 1500g, water 3500g, arginine addition amount 40g, grinding speed setting 2500r / min, grinding time: 1.5h, then add vinyl triethoxysilane 10g, continue to grind for 4h, take out the ground slurry, centrifuge at 9000r / min for 6min, wash 4 times, then place in an oven at 120℃ for 24h drying, then grind in a ball mill at 600r / min for 8min to grind into powder, and sieve the powder through a 80 mesh screen.

[0059] Add high dispersion silica 818.18g, the specific steps for preparing the rubber composite material are the same as in Example 1.

[0060] Preparation of rubber composite material Example 3 Preparation of high dispersion nano-silica: Hydrated nano-silica (20 nm) 1500g, water 3500g, arginine addition amount 50g, grinding speed setting 3000r / min, grinding time: 1h, then add vinyl triethoxysilane 20g, continue to grind for 3h, take out the ground slurry, centrifuge at 12000r / min for 5min, wash 4 times, then place in an oven at 150℃ for 24h drying, then grind in a ball mill at 550r / min for 10min to grind into powder, and sieve the powder through a 80 mesh screen.

[0061] The high-dispersed silica was added in an amount of 1 Kg, and the rubber composite was prepared according to the steps in Example 1.

[0062] Comparative Example 6 The rubber composite was prepared, and in the modification step, no high-dispersed silica prepared according to the application was added, but instead, 0%, 10%, 20%, 30%, 40%, and 50% of commercially available nano-silica was added, respectively, and the other steps were the same as in Example 1.

[0063] Table 1. Mechanical properties of the rubber composite prepared by adding commercially available nano-silica in different proportions in Comparative Example 6

[0064] Comparative Example 7 The rubber composite was prepared, and in the modification step, high-dispersed nano-silica prepared according to Comparative Example 4 was added in the same proportion, and the other steps were the same as in Example 1. Table 2. Mechanical properties of the rubber composite prepared in Example 1 and Comparative Example 7

[0065] As shown in Table 1, when the addition amount of commercially available nano-silica in the rubber matrix is 40%, the mechanical properties of the prepared rubber composite are optimal, and the tensile strength reaches 500 MPa; when the addition amount of commercially available nano-silica reaches 50%, the tensile strength of the rubber composite is 476 MPa, that is, when the addition amount of commercially available nano-silica is higher than 40%, the tensile strength of the rubber composite decreases.

[0066] As shown in Table 2, the test results show that the tensile strength of Comparative Example 7 is 625 MPa (the addition amount of modified silica is 40%), the tensile strength of Example 1 is 741 MPa (the addition amount of modified silica is 50%), and the tensile strength of Example 2 is 702 MPa (the addition amount of modified silica is 45%), all of which are higher than 40% of the commercially available nano-silica. The test data show that the modified nano-silica prepared according to the application can be well dispersed in the rubber matrix, and after being grafted with vinyl triethoxysilane, the nano-silica can be better dispersed in the rubber matrix, and can be better interpenetrated in the rubber system during the vulcanization process, so that the nano-silica can be uniformly distributed in the rubber "space network structure", and the performance of the rubber composite can be improved. The nano-silica modified by vinyl triethoxysilane and arginine can be better compatible with the rubber matrix, and can be better interpenetrated in the rubber matrix during the vulcanization process, and can be uniformly distributed in the rubber space network, thereby improving the mechanical properties of the rubber composite. At the same time, a high filling amount of nano-silica can effectively reduce the cost of the rubber composite.

[0067] Referring to the rubber cost price comparison of different silica addition amounts shown in Table 3 below, it can be seen that for the preparation of 1 ton of rubber composite material, the use of high-dispersion silica can save about 7000 yuan compared with the use of ordinary silica.

[0068] The cost of rubber composite material added with ordinary silica: 600x0.7x85+600x0.3x67+4.5x400=49560 yuan The cost of rubber composite material added with modified silica: 500x0.7x85+500x0.3x67+500x7=42600 yuan Because the addition amount of modified silica is more than that of ordinary silica, the use amount of styrene-butadiene rubber and butadiene rubber is reduced, and the mechanical properties of the composite rubber are improved instead, so the cost of the composite rubber added with the modified silica of the application is much lower than that of the composite rubber added with ordinary commercially available silica, which can significantly improve the profit margin and product performance of the product, and improve the product competitiveness.

[0069] Table 3 Rubber cost price comparison of different silica addition amounts

[0070] For those skilled in the art, without departing from the principles of the application, a number of improvements and refinements can be made, which should also be considered within the scope of protection of the application.

Claims

1. A method for preparing highly dispersed nanosilica, characterized by, The method comprises the following steps: S1, modification: mixing hydrated nanosilica, aqueous medium and arginine in a predetermined ratio to form a mixed slurry, sanding the mixed slurry, generating active sites on the surface of the hydrated nanosilica through high-energy grinding, and grafting arginine with the active sites and the surface hydroxyl groups of the hydrated nanosilica to form a modified mixed slurry during the sanding process; S2, silane coupling agent grafting: adding a predetermined amount of silane coupling agent to the modified mixed slurry to graft the silane coupling agent on the surface of the hydrated nanosilica; S3, post-treatment: solid-liquid separation, washing, drying and grinding into powder of the slurry treated in step S2 to obtain high-dispersion nanosilica.

2. The method for preparing highly dispersed nano-silica according to claim 1, characterized in that, In step S2, the silane coupling agent is directly added to the grinding mechanism treated in step S1, and the sanding process is continued for a predetermined time to complete the grafting of the silane coupling agent.

3. The method for preparing highly dispersed nano-silica according to claim 2, characterized in that, In step S1, the mass ratio of the hydrated nanosilica, the aqueous medium and the arginine is 150:350:4-5.

4. The method for preparing highly dispersed nano-silica according to claim 3, characterized in that, The silane coupling agent is vinyltriethoxysilane.

5. The method for preparing highly dispersed nano-silica according to claim 4, characterized in that, The mass ratio of the arginine to the silane coupling agent is 4-5:1-2.

6. The method for preparing highly dispersed nano-silica according to any one of claims 2 to 5, characterized in that, The sanding time in step S1 is 1-1.5 hours, the sanding time in step S2 is 3-4 hours, and the rotation speed of the sanding is 2500-3000 r / min.

7. A highly dispersed nanosilica, characterized in that, The high-dispersion nanosilica is prepared by the method of any one of claims 1-6.

8. A rubber composite material characterized by, The raw material comprises the high-dispersion nanosilica of claim 7.

9. The rubber composite of claim 8, wherein, The addition amount of the high-dispersion nanosilica is 45-55% based on the total weight of the rubber.

10. Process for the production of a rubber composite material according to claim 8 or 9, characterized in that, The method comprises the following steps: Banbury mixing: Banbury mixing and dispersing the rubber matrix; Modification: adding the high-dispersion nanosilica to the rubber matrix for further Banbury mixing and dispersing to prepare a rubber composite; Vulcanization: vulcanizing the rubber composite. The method comprises the following steps: Banbury mixing: Banbury mixing and dispersing the rubber matrix; Modification: adding the high-dispersion nanosilica to the rubber matrix for further Banbury mixing and dispersing to prepare a rubber composite; Vulcanization: vulcanizing the rubber composite.

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