CN110028702B

CN110028702B - Nano-silica-doped nano-cellulose material and preparation method and application thereof

Info

Publication number: CN110028702B
Application number: CN201910353571.6A
Authority: CN
Inventors: 唐磊; 张金柱; 张延伟; 马洁
Original assignee: Jinan Shengquan Group Share Holding Co Ltd
Current assignee: Jinan Shengquan Group Share Holding Co Ltd
Priority date: 2019-04-29
Filing date: 2019-04-29
Publication date: 2022-03-08
Anticipated expiration: 2039-04-29
Also published as: CN110028702A

Abstract

The invention provides a nano-silica doped nano-cellulose material and a preparation method and application thereof, wherein at least partial hydrogen bond combination exists between the nano-silica and the nano-cellulose material; the mass percentage of the nano silicon dioxide is 70-90% based on the total mass of the nano silicon dioxide doped nano cellulose material as 100%. The nano-silicon dioxide has better dispersibility in rubber, so that nano-cellulose connected with the nano-silicon dioxide through partial hydrogen bonds can be uniformly dispersed in the rubber, the use of surfactants such as silane coupling agents and the like can be reduced, the product cost is indirectly reduced, the specific gravity of the product is reduced, and meanwhile, the nano-cellulose material is a green environment-friendly material, so that the pressure of the traditional modified material on the environment can be relieved.

Description

Nano-silica-doped nano-cellulose material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of modified materials, and relates to a nano-silica doped nano-cellulose material, and a preparation method and application thereof.

Background

Cellulose is a rich natural renewable biopolymer material that is widely distributed in higher plants, but also in marine animals, algae, bacteria, fungi, and invertebrates. Cellulose undergoes mechanical shearing and chemical action to transversely decompose cellulose fibers into its substructure nano-units, producing nanocellulose (MFC). Due to the characteristics of high modulus, reproducibility, degradability and the like, the reinforcing agent becomes a hot spot when being used for reinforcing high polymer materials such as rubber and the like in recent years. However, like other nano materials, nanocellulose has strong agglomeration property, has poor dispersibility in high polymer materials such as rubber and the like, and cannot play a role, and a simple and low-cost method for adding and dispersing is not available at present.

The nano silicon dioxide is an inorganic chemical material and is commonly called white carbon black. Due to the ultrafine nanometer size, the size range is 1-100nm, so the material has a plurality of unique properties, such as optical performance for resisting ultraviolet rays, and the aging resistance, the strength and the chemical resistance of other materials can be improved, and the material is not used forIs often widespread. The nanometer silicon dioxide is amorphous white powder, has no toxicity, no odor and no pollution, and has spherical microstructure, flocculent and reticular quasi-particle structure, and SiO has molecular formula and structural formula₂And is insoluble in water. The application of the nano silicon dioxide is very wide, and the nano silicon dioxide can be applied to the following fields: electronic packaging materials, resin composite materials, plastics, coatings, pigments (dyes), ceramics, sealants, glass fiber reinforced plastic products, drug carriers, cosmetics, antibacterial materials, rubbers and the like. Adding a small amount of nano SiO into common rubber₂And then, the strength, wear resistance, ageing resistance and other properties of the product can reach or exceed those of high-grade rubber products, and the color can be kept unchanged for a long time. The surface of the silica powder has hydroxyl groups and siloxane groups, and researches prove that the surface of the silica powder has three hydroxyl groups (adjacent hydroxyl groups, isolated hydroxyl groups and double hydroxyl groups), the hydroxyl groups have strong activity, the adjacent hydroxyl groups are combined with each other in a hydrogen bond mode, and the silica powder has an adsorption effect on polar substances, and when a system such as rubber is added, the active hydroxyl groups free on the surface of the silica can adsorb the polar substances such as an accelerator, so that a delay effect on the vulcanization of the rubber can be generated after the silica is added into the rubber system.

CN106519352A discloses a microcrystalline cellulose-nano silicon dioxide hybrid material, a preparation method and an application thereof, wherein the patent uses tetraethoxysilane and a coupling agent (Si69) as silicon sources, adopts a 'microreactor' technology combined with a 'sol-gel' technology, utilizes hydroxyl on the surface of swelling microcrystalline cellulose to lead a catalyst NaOH required by a sol-gel reaction to be introduced into the microreactor formed by the surface and the inside of the microcrystalline cellulose, then catalyzes the sol-gel reaction to lead nano silicon dioxide to be loaded on the surface and the inside of the microcrystalline cellulose, and obtains the hybrid material by filtering and drying, and the hybrid material is applied to rubber to study the influence of the hybrid material on the rubber performance. The raw material adopted by the patent is microcrystalline cellulose, belongs to a non-nano material, and does not really solve the problem of agglomeration of the nano material, so that the modified rubber prepared by using the microcrystalline cellulose as the filler has obviously reduced performance; meanwhile, the silicon dioxide adsorbs the accelerator in the formula to delay the vulcanization time, so a large amount of silane coupling agent needs to be added in the formula for surface active treatment before use, and the product cost is further increased. CN107892762 discloses a preparation method of a composite material based on waste bamboo pulp fiber paper and hydrogenated nitrile butadiene rubber, which comprises the steps of firstly stirring and crushing the waste bamboo pulp fiber paper at a high speed into paper pulp, then performing alkaline hydrolysis, homogenizing to obtain nano-sized cellulose, hydrogenating the modified nitrile butadiene latex by a hydrazine hydrate method, adding oxidized starch for compounding, mixing with other additives to obtain oxidized starch composite hydrogenated nitrile butadiene rubber latex, then adding nano-sized cellulose into the latex, adding toughened latex, and preparing a composite material based on the waste bamboo pulp fiber paper and hydrogenated nitrile butadiene rubber by a coacervation method.

CN107419599 discloses a carboxymethyl cellulose modified nano-silica, which comprises the following raw materials in parts by weight: 8-12 parts of carboxymethyl cellulose, 2-3 parts of nano silicon dioxide, 80-85 parts of styrene sodium and 20-30 parts of ethyl acetate, wherein the prepared carboxymethyl cellulose modified nano silicon dioxide has good performance and can be applied to paper making, but the problems of whether the carboxymethyl cellulose modified nano silicon dioxide can be used as a reinforcing material and dispersion performance in other high polymer materials are not paid much attention.

There is a need to develop a method for reducing the agglomeration of nanocellulose so that nanocellulose can be better used as a reinforcing material.

Disclosure of Invention

The invention aims to provide a nano-silica doped nano-cellulose material, and a preparation method and application thereof. The nano-silica doped nano-cellulose material provided by the invention can be uniformly dispersed in materials such as rubber and plastics under the condition of reducing the addition amount of surfactants such as silane coupling agents, and has an excellent reinforcing effect on matrix materials.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides a nano-silica doped nano-cellulose material, wherein at least partial hydrogen bonding exists between the nano-silica and the nano-cellulose material; the content of the nano-silica is 70-90% by mass, such as 72%, 75%, 78%, 80%, 82%, 85%, 88%, and the like, based on 100% by mass of the total nano-silica-doped nano-cellulose material.

The hydroxyl on the surface of the nano silicon dioxide can form a hydrogen bond with the hydroxyl on the surface of the nano cellulose material, and the hydroxyl and the nano cellulose material are synergistic, so that on one hand, the formed hydrogen bond can reduce the number of the hydroxyl on the surface of the nano silicon dioxide, reduce the adsorption of the hydroxyl on polar substances such as an accelerant and the like, improve the delayed effect on vulcanization, and simultaneously, reduce the defect that the nano cellulose material is easy to agglomerate due to the existing hydroxyl.

And the nano-silica has better dispersibility in rubber, so that the nano-cellulose connected with the nano-silica through partial hydrogen bonds can be uniformly dispersed in the rubber, the use of surfactants such as silane coupling agents and the like can be reduced, the product cost is indirectly reduced, the product specific gravity is reduced (the density of nano-silica doped nano-cellulose material is lower than that of the nano-silica), and meanwhile, the nano-cellulose material is a green environment-friendly material, so that the pressure of the traditional modified material on the environment can be relieved.

Preferably, the content of the nano-silica is 80-90% by mass, such as 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% and the like, based on 100% by mass of the total mass of the nano-silica doped nano-cellulose material.

When the content of the nano-cellulose material is 10-20%, the nano-cellulose material can be well dispersed without agglomeration, and meanwhile, the tensile strength of the rubber can be improved, the defect that the vulcanization of the rubber is delayed in the application process of the white carbon black in the rubber is overcome, so that the vulcanization efficiency is improved, the ML (minimum torque) can be reduced, and the processability of the rubber is improved.

The nano-silica doped nano-cellulose material has small average particle size and small particle size distribution, so that the nano-silica doped nano-cellulose material can be uniformly dispersed in high polymer materials such as rubber and the like.

Preferably, the nanosilica has an average particle size of 28-32nm, such as 29nm, 30nm, 31nm, etc., more preferably 30 nm.

Preferably, the nanocellulose material has an average diameter of 8-20nm, such as 9nm, 10nm, 12nm, 15nm, 18nm, etc., and an aspect ratio of 100-200, such as 120, 150, 180, etc.

According to the invention, the nano-cellulose material with the diameter and the length-diameter ratio within a certain range is preferably selected, at the moment, hydrogen bonds between nano-silica and the nano-cellulose material are more, and the modification effect on rubber and the like is better.

Preferably, the nanocellulose material comprises nanocellulose and/or micro-nanocellulose.

The micro-nano lignocellulose adopted by the invention refers to micro-nano cellulose containing lignin components, and can be understood as cellulose materials containing lignin and having the diameter size within 1 nm-1 mu m.

The nano-cellulose material used in the invention can be selected from nano-cellulose and micro-nano lignocellulose, wherein the micro-nano lignocellulose is micro-nano cellulose containing lignin components.

Preferably, the lignin content is 20-25 wt%, such as 21 wt%, 22 wt%, 23 wt%, 24 wt%, etc., based on the mass of the micro-nano lignocellulose as 100%.

In the invention, the raw materials for preparing the nano-silica doped nano-cellulose material comprise the following components in parts by weight:

160-600 parts by weight of nano-cellulose material dispersion liquid;

400 parts of sodium metasilicate solution;

120 portions of sulfuric acid solution and 140 portions of sulfuric acid solution.

In the present invention, the nano-cellulose material dispersion liquid 160-600 parts by weight, for example, 200 parts by weight, 220 parts by weight, 250 parts by weight, 280 parts by weight, 300 parts by weight, 320 parts by weight, 350 parts by weight, 400 parts by weight, 450 parts by weight, 500 parts by weight, 550 parts by weight, etc.

In the present invention, the sodium metasilicate solution is 300-400 parts by weight, for example, 310 parts by weight, 320 parts by weight, 330 parts by weight, 350 parts by weight, 370 parts by weight, 380 parts by weight, and the like.

In the present invention, the sulfuric acid solution 120-.

Preferably, the concentration of the nanocellulose material dispersion is 5-8%, such as 5.5%, 6%, 6.5%, 7%, 7.5%, and the like.

In the present invention, if the concentration of the nano cellulose material dispersion is too low, the concentration of sodium metasilicate may be too low, and the amount of water to be recovered may be greatly increased, and at the same time, the amount of acid used may be increased, thereby decreasing the preparation efficiency, and if the concentration of the nano cellulose material dispersion is too high, the time for dispersing in the sodium metasilicate solution may be increased, thereby indirectly increasing the production cost.

Preferably, the concentration of the sodium metasilicate solution is 20-25%, such as 21%, 22%, 23%, 24%, etc.

If the concentration of the sodium metasilicate solution is too low, the amount of water used is increased, which indirectly increases the cost, and if the concentration is too high, the resulting silica particles may be non-uniform and the particle size distribution may be large.

Preferably, the sodium metasilicate is selected from any one of sodium metasilicate pentahydrate, sodium metasilicate nonahydrate, or anhydrous sodium metasilicate, or a combination of at least two thereof, and sodium metasilicate pentahydrate is more preferred.

Preferably, the concentration of the sulfuric acid solution is 12-20 wt%, such as 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, etc.

In a second aspect, the present invention provides a method for preparing a nanosilica-doped nanocellulose material according to the first aspect, said method comprising the steps of:

and mixing the nano-cellulose material dispersion liquid with a sodium metasilicate solution, adding a sulfuric acid solution into the mixed solution until the pH value is 7-8, and aging, filtering and drying to obtain the nano-silica doped nano-cellulose material.

The mode of reacting in situ to generate the nano silicon dioxide in the nano cellulose material dispersion liquid by using the sodium metasilicate as a silicon source can enable more hydroxyl groups carried by the silicon dioxide to be combined with hydroxyl groups on the surface of the nano cellulose material in a hydrogen bond mode, and the two generate a synergistic effect, so that the quantity of free active hydroxyl groups on the surface of the silicon dioxide can be reduced, the adsorption of the free active hydroxyl groups on polar substances such as an accelerant and the like can be reduced, the delayed effect on vulcanization can be improved, and the effect of agglomeration of the nano cellulose material due to the active hydroxyl groups can be reduced.

The invention adopts low-cost sodium metasilicate as the silicon source, has low production cost and does not have the environmental pressure caused by the traditional filler.

The preparation method provided by the invention is simple, the reaction condition is mild, and the energy consumption is low.

Preferably, the drying mode is any one or combination of at least two of spray drying, atmospheric drying or freeze drying, and spray drying is preferred.

The invention prefers spray drying, the spray drying mode can directly obtain powder materials, the particle size is smaller, the particle size distribution is more uniform, and the process of granulating after drying in other drying modes is omitted.

Preferably, the temperature of the spray drying is 150-.

Preferably, the spray drying has a spray pressure of 0.36-0.42MPa, such as 0.38MPa, 0.40MPa, and the like.

Preferably, during said spray drying, the feeding speed of the peristaltic pump is 20-25r/min, such as 21r/min, 22r/min, 23r/min, 24r/min, etc.

Preferably, the manner of adding the sulfuric acid solution is dropwise.

Preferably, the time of the dropwise addition is 1 to 3 hours, such as 1.2 hours, 1.5 hours, 1.7 hours, 2 hours, 2.2 hours, 2.5 hours, 2.7 hours and the like.

Preferably, the mixing time is 0.5 to 3h, such as 0.8h, 1.0h, 1.2h, 1.5h, 1.7h, 2h, 2.2h, 2.5h, 2.7h, and the like.

Preferably, the aging time is from 2 to 4h, such as 2.1h, 2.3h, 2.4h, 2.5h, 2.7h, 2.9h, 3.0h, 3.2h, 3.5h, 3.7h, and the like.

Preferably, the temperature of said mixing, adding the sulfuric acid solution and aging is each independently selected from 70-80 ℃, such as 72 ℃, 75 ℃, 78 ℃ and the like.

Preferably, the mixing, adding and aging agitation rates are each independently selected from 200-400r/min, such as 250r/min, 280r/min, 300r/min, 320r/min, 350r/min, 380r/min, and the like.

Preferably, a post-filtration wash is also included.

Preferably, the washing is washing to a conductivity of the filtrate of 0.1-1.0us/cm (e.g., 0.2us/cm, 0.5us/cm, 0.8us/cm, etc.) and a pH of 7-8.

In a third aspect, the present invention provides the use of a nanosilica doped nanocellulose material according to the first aspect as a reinforcing material.

Preferably, the use of a nanosilica doped nanocellulose material according to the first aspect as a rubber or plastic reinforcement.

The nano-silica doped nano-cellulose material provided by the invention can completely replace the application of white carbon black in rubber, can overcome the defect that the vulcanization of the rubber is delayed in the application process of the white carbon black in the rubber, and can improve the vulcanization efficiency of the rubber.

In a fourth aspect, the nanosilica doped nanocellulose material according to the first aspect is used in papermaking or in coating.

In a fifth aspect, the present invention provides a modified rubber comprising the nanosilica-doped nanocellulose material of the first aspect.

Preferably, the composition comprises the following components in parts by weight:

in the traditional preparation process of the modified rubber by using the white carbon black or the nano-cellulose material, the white carbon black or the nano-cellulose material dispersion liquid is generally dispersed into the latex of natural rubber and styrene butadiene rubber, then the emulsion breaking and the drying dehydration are carried out to prepare the master batch, and the prepared master batch is mixed and added with other auxiliary agents on an open mill. The preparation method is complicated, the energy consumption problem in the rubber mixing engineering is increased, and the production cost is indirectly increased.

In the present invention, the nanosilica doped nanocellulose material described in the first aspect is 45-50 parts, such as 46 parts, 47 parts, 48 parts, 49 parts and the like.

In the present invention, the active agent is 10 to 15 parts, such as 11 parts, 12 parts, 13 parts, 14 parts, etc.

The activator may be any one or a combination of at least two of stearic acid, zinc oxide, polyethylene glycol, and the like.

In the present invention, the antioxidant is used in an amount of 1 to 2 parts, for example, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, etc.

The antioxidant can be antioxidant RD.

In the present invention, the accelerator is 1 to 3 parts, for example, 1.5 parts, 2 parts, 2.2 parts, 2.8 parts, etc.

The promoter may be a promoter CZ, DM, or the like.

In the present invention, the sulfur is 1 to 3 parts, for example, 1.5 parts, 2 parts, 2.2 parts, 2.8 parts, etc.

The nano-silica doped nano-cellulose material provided by the invention can be used as a reinforcing material to be added into a rubber material, and has a relatively excellent reinforcing effect on the rubber material.

Compared with the prior art, the invention has the following beneficial effects:

(1) in the nano-silica doped nano-cellulose material provided by the invention, part of nano-silica is combined with the nano-cellulose material through hydrogen bonds, and the nano-silica has a good dispersion effect in materials such as rubber, so that nano-cellulose connected with the nano-silica through part of the hydrogen bonds can be uniformly dispersed in the rubber, the use of surfactants such as silane coupling agents can be reduced, the product cost is indirectly reduced, the specific gravity of the product is reduced, and meanwhile, the nano-cellulose material is a green environment-friendly material, so that the pressure of the traditional modified material on the environment can be relieved;

(2) the preparation method provided by the invention is simple and feasible, mild in reaction condition, low in cost and low in energy consumption;

(3) when the nano-silica doped nano-cellulose material provided by the invention is applied to rubber, the defect of delayed vulcanization of the rubber in the application process of white carbon black can be overcome, the vulcanization efficiency of the rubber is improved, and the nano-silica doped nano-cellulose material has an excellent reinforcing effect on the rubber, wherein the tensile strength is more than 14.4MPa and can reach more than 18MPa at most, and the vulcanization time is within 600 s.

Drawings

FIG. 1 is a scanning electron micrograph of the nano-silica doped nano-cellulose material prepared in example 1.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Preparation example 1

The nano-silica doped nano-cellulose material is characterized in that at least partial hydrogen bonding exists between the nano-silica and the nano-cellulose material, and the mass percentage of the nano-silica is 90%.

The preparation method comprises the following steps:

(1) the nano-cellulose (average diameter of 10nm, length-diameter ratio of 100-120) dispersion with concentration of 6% and sodium metasilicate solution with concentration of 22% were mixed at 78 ℃ and stirring speed of 340r/min for 40min, and then sulfuric acid solution with concentration of 20 wt% was added dropwise until pH was 8, and the adding time was 1.5 h.

(2) Stopping dropwise adding the sulfuric acid solution, aging for 2h, keeping the stirring speed and temperature under the conditions, filtering and washing until the conductivity of the filtrate is within the range of 0.1-1.0us/cm and the pH is 7, and finally performing spray drying at 170 ℃ to obtain the nano-silica doped nano-cellulose material.

The microscopic morphology of the nano-silica doped nano-cellulose material obtained by the scanning electron microscope observation is shown in fig. 1, and it can be known from the figure that nano-cellulose is similar to a dendritic structure, and nano-silica is dispersed on the surface of nano-cellulose, and the nano-cellulose has good dispersibility and is not agglomerated.

Preparation examples 2 to 5

The difference from preparation example 1 was that the nanocellulose dispersion had a concentration of 5% (preparation example 2), 8% (preparation example 3), 3% (preparation example 4), 10% (preparation example 5).

Preparation examples 6 to 9

The difference from preparation example 1 was that the sodium metasilicate solution had a concentration of 20% (preparation example 6), 25% (preparation example 7), 15% (preparation example 8) and 30% (preparation example 9).

Preparation example 10

The difference from preparation example 1 is that the average diameter of the nano-cellulose is 30nm, the aspect ratio is 100-140 (preparation example 10), the average diameter is 15nm, the aspect ratio is 200-220 (preparation example 11), the average diameter is 30nm, and the aspect ratio is 300-350 (preparation example 12).

Preparation example 13

The difference from the preparation example 1 is that the nano-cellulose is replaced by micro-nano lignocellulose, the lignin content is 22 wt%, the diameter is 15nm, and the length-diameter ratio is 100-150.

Preparation examples 14 to 15

The difference from preparation example 1 is that the drying method of this preparation example was oven atmospheric drying (preparation example 14) and freeze drying (preparation example 15).

The doped materials obtained in preparation examples 14-15 can be subjected to post-treatment such as ball milling to obtain powdery nano-silica doped nano-cellulose materials.

Preparation examples 16 to 17

The difference from preparation example 1 is that the ratio of the nano-cellulose dispersion and the sodium metasilicate solution was controlled so that the nano-silica content of the finally obtained nano-silica doped nano-cellulose material was 80% (preparation example 16) and 70% (preparation example 17).

Preparation example 18

The preparation method comprises the following steps:

(1) the 6 percent nano-cellulose (average diameter is 10nm, length-diameter ratio is 100-120) dispersion liquid and 22 percent sodium metasilicate solution are mixed for 1.5h at 70 ℃ and stirring speed of 400r/min, and then 12 percent by weight of sulfuric acid solution is dripped until the pH value is 8, and the dripping time is 3 h.

(2) Stopping dropwise adding the sulfuric acid solution, aging for 3h, filtering and washing until the conductivity of the filtrate is within the range of 0.1-1.0us/cm and the pH is 7-8, and finally performing spray drying at 180 ℃ to obtain the nano-silica doped nano-cellulose material.

Preparation example 19

The preparation method comprises the following steps:

(1) the nano-cellulose (average diameter of 10nm, length-diameter ratio of 100-120) dispersion with concentration of 6% and sodium metasilicate solution with concentration of 22% were mixed at 80 ℃ and stirring speed of 200r/min for 3h, and then sulfuric acid solution with concentration of 20 wt% was added dropwise until pH was 8, and the adding time was 2 h.

(2) Stopping dropwise adding the sulfuric acid solution, aging for 4h, filtering and washing until the conductivity of the filtrate is within the range of 0.1-1.0us/cm and the pH is 7-8, and finally performing spray drying at 180 ℃ to obtain the nano-silica doped nano-cellulose material.

Preparation example 20

Nanosilica was prepared according to the preparation method provided in preparation example 1, nanosilica was mixed with a nanocellulose dispersion (nanocellulose used in example 1) at a stirring rate of 340r/min at 78 ℃ for 250min (sum of mixing reaction time in example 1) according to a ratio of nanosilica to nanocellulose of 9:1, and then filtered and washed until the conductivity of the filtrate was in the range of 0.1-1.0us/cm and pH was 7, and finally spray-dried at 170 ℃ to obtain a doped material.

Comparative preparation example 1

The nano-silica is prepared according to the preparation method provided by the preparation example 1, and the preparation process conditions are consistent with those of the preparation example 1.

Comparative preparation example 2

The doped material provided by the comparative preparation example is the microcrystalline cellulose-nano silicon dioxide hybrid material provided by CN106519352A example 1.

Comparative preparation examples 3 to 4

The difference from preparation example 1 is that the ratio of the nano-cellulose dispersion and the sodium metasilicate solution was controlled so that the nano-silica content of the finally obtained nano-silica doped nano-cellulose material was 65% (comparative preparation example 3) and 95% (comparative preparation example 4).

Examples 1 to 20

A modified rubber comprises the following components in parts by weight:

wherein the nano-silica doped nano-cellulose material is the nano-silica doped nano-cellulose material provided in preparation examples 1-20.

The preparation method comprises the following steps: firstly, adjusting the roller spacing to 1.2mm, putting rubber into a roller before plastication and wrapping, and making 3/4 cutters once on each side for 3 min; adding stearic acid, zinc oxide and RD at room temperature, and performing 3/4 cutters twice on each side for 2 min; thirdly, nano-silicon dioxide doped nano-cellulose material, PEG 4000 and Si69 are added, after all powder is mixed, 3/4 cutters are made for 4 times each side for 8 min; fourthly, the roller spacing is set to be 1.6mm, sulfur, CZ and DM are added, after the mixture is mixed, 3/4 cutters are made for 2 times at each side, and the time is 3 min; fifthly, adjusting the roller distance to 0.8mm, performing thin passing for 7 times, and then discharging the sheet; sixthly, after the mixed rubber sheet is stood for 4 hours at room temperature, the vulcanization curve of the mixed rubber at 150 ℃ is tested, and the relevant data of the vulcanization curve are shown in the table 1; seventhly, vulcanizing the mixed rubber on a flat vulcanizing machine under the conditions of 150 ℃, 15min and 10 MPa; cutting the vulcanized rubber sheet into samples, testing the tensile strength of the samples, and the test results of the tensile strength are shown in table 2.

Comparative examples 1 to 4

The only difference from example 1 is that the nanosilica doped nanocellulose material was replaced with the doped material provided in comparative preparation examples 1-4.

Comparative example 5

The difference from example 1 is that the nanosilica doped nanocellulose material was replaced with nanocellulose and nanosilica, wherein the ratio of nanocellulose and nanosilica was 1:9 (same as the ratio of nanosilica and nanocellulose in preparation example 1).

Comparative example 6

The difference from example 1 is that the nanosilica-doped nanocellulose material was replaced with 48 parts of nanocellulose (as nanocellulose used in preparation example 1).

Performance characterization

The rubbers provided in examples 1 to 20 and comparative examples 1 to 6 were subjected to a performance test as follows:

(1) vulcanization curve: the method is carried out according to the method for measuring the vulcanization characteristics of the rubber in GB/T16584 by a rotor-free vulcanizer, wherein the test temperature is 150 ℃, and the test time is 20 min.

(2) Tensile strength: according to the measuring method of the tensile property of the vulcanized rubber and the thermoplastic rubber in GB/T528;

the test results are shown in table 1:

TABLE 1

In the invention, whether the nano-silica doped nano-cellulose material is uniformly dispersed can be judged by comparing the tensile strength, and the larger the tensile strength is, the more uniformly the nano-silica doped nano-cellulose material is dispersed in rubber is shown.

According to the embodiment and the performance test, the nano-silica doped nano-cellulose material provided by the invention can be uniformly dispersed in rubber, the tensile strength of the rubber can be improved, the defect of delayed vulcanization caused by adding white carbon black is overcome, the vulcanization efficiency of the rubber is improved, the minimum torque ML in the rubber processing process is reduced, and the processability of the rubber is improved.

It is understood from the comparison between example 1 and examples 2 to 5 that the concentration of the dispersion of the nano-cellulose material is preferably 5 to 8% in the process of preparing the nano-silica doped nano-cellulose material, and when the concentration is not within this range, the dispersion effect of the finally obtained material in the rubber may be affected due to the slightly poor dispersibility of the nano-silica hybrid nano-cellulose material. As is clear from the comparison between example 1 and examples 6 to 9, the concentration of the sodium metasilicate solution is 20 to 25%, and when it is out of this range, the dispersion effect of the finally obtained material in the rubber may be affected by the slightly poor dispersibility of the hybrid material. As can be seen from the comparison between example 1 and example 10, the invention prefers the nano-cellulose material with the diameter of 8-20nm and the aspect ratio of 100-200, and in this case, the nano-cellulose material has better modification effect on the modified rubber. As can be seen from the comparison between example 1 and example 11, the nanocellulose material of the present invention can be nanocellulose or micro-nanocellulose. As can be seen from the comparison between example 1 and examples 12-13, the spray drying method is preferred in the present invention, and the post-treatment of other drying methods can be omitted, thereby saving the cost. As can be seen from the comparison between example 1 and examples 14-15, in the nanosilica-doped nanocellulose material provided by the invention, the mass percentage of the nanosilica is preferably 80-90%, and when the nanosilica content is low, part of the nanocellulose may have an agglomeration phenomenon. As can be seen from the comparison between example 1 and example 18, the nanosilica doped nanocellulose material prepared by the preparation method provided by the invention has better modification effect when applied to rubber.

As can be seen from the comparison between the example 1 and the comparative example 1, the nano-silica doped nano-cellulose material of the invention can replace white carbon black to be used as a reinforcing agent of rubber, can improve the defect of delayed vulcanization after the white carbon black is added, improves the vulcanization efficiency of the rubber, reduces ML in the rubber processing process, and improves the processability of the rubber. As can be seen from the comparison between example 1 and comparative example 2, the nano-silica doped nano-cellulose material of the present invention has a modification effect on rubber far superior to that of comparative example 2 at a nano level. As can be seen from the comparison between example 1 and comparative examples 3-4, in the nano-silica doped nano-cellulose material adopted in the present invention, the effect is best when the content of nano-silica is within 70-90%, if the content of nano-silica is small, the nano-cellulose will have agglomeration phenomenon to affect the performance of rubber, and if the addition amount of nano-silica is too large, the production time will be prolonged due to the delayed vulcanization of rubber caused by nano-silica. It can be seen from the comparison between example 1 and comparative example 5 that the direct addition of nanocellulose and nanosilica does not result in the complete and uniform dispersion of nanocellulose in rubber, and further affects the modification effect of nanocellulose. As can be seen from the comparison between example 1 and comparative example 6, the nanosilica doped nanocellulose material provided by the present invention can be uniformly dispersed in rubber.

The applicant states that the present invention is illustrated by the above examples of the nanosilica doped nanocellulose material of the present invention and the preparation method and application thereof, but the present invention is not limited to the above process steps, i.e. it does not mean that the present invention must rely on the above process steps to be carried out. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.

Claims

1. A nanosilica doped nanocellulose material, characterised in that there is at least partial hydrogen bonding between the nanosilica and the nanocellulose material;

the mass percentage of the nano silicon dioxide is 81-90% calculated by the total mass of the nano silicon dioxide doped nano cellulose material being 100%;

the nano-silica doped nano-cellulose material is prepared by adopting the following method, and the method comprises the following steps:

mixing the nano-cellulose material dispersion liquid with a sodium metasilicate solution, adding a sulfuric acid solution into the mixed solution until the pH value is 7-8, and aging, filtering and drying to obtain the nano-silica doped nano-cellulose material;

the concentration of the sodium metasilicate solution is 20-25%;

the concentration of the nano-cellulose material dispersion liquid is 5-8%;

the average diameter of the nano-cellulose material is 8-20nm, and the length-diameter ratio is 100-200.

2. The nanosilica-doped nanocellulose material of claim 1, wherein the nanosilica has an average particle size of 28-32 nm.

3. Nanosilica doped nanocellulose material as claimed in claim 2, characterised in that said nanosilica has an average particle size of 30 nm.

4. The nanosilica-doped nanocellulose material of claim 1, wherein the nanocellulose material comprises nanocellulose and/or micronano lignocellulose.

5. The nanosilica-doped nanocellulose material of claim 4, wherein the lignin content is 20-25 wt% based on the mass of the micro-nano lignocellulose as 100%.

6. The nano-silica doped nano-cellulose material as claimed in claim 1, wherein the raw materials for preparing the nano-silica doped nano-cellulose material comprise the following components in parts by weight:

160-600 parts by weight of nano-cellulose material dispersion liquid;

400 parts of sodium metasilicate solution;

7. The nanosilica-doped nanocellulose material of claim 6, wherein the sodium metasilicate is selected from any one of sodium metasilicate pentahydrate, sodium metasilicate nonahydrate, or sodium metasilicate anhydrous or a combination of at least two thereof.

8. The nanosilica-doped nanocellulose material of claim 7, wherein the sodium metasilicate is sodium metasilicate pentahydrate.

9. The nanosilica-doped nanocellulose material of claim 6, wherein the concentration of the sulfuric acid solution is from 12 to 20 wt%.

10. The method for the preparation of nanosilica doped nanocellulose material according to any of claims 1-9, characterized in that it comprises the steps of:

11. The method according to claim 10, wherein the drying is performed by any one or a combination of at least two of spray drying, atmospheric drying, and freeze drying.

12. The method according to claim 11, wherein the drying is performed by spray drying.

13. The method as claimed in claim 12, wherein the temperature of the spray drying is 150 ℃ to 180 ℃.

14. The method of claim 13, wherein the temperature of the spray drying is 170 ℃.

15. The method of claim 12, wherein the spray drying has a spray pressure of 0.36 to 0.42 MPa.

16. The method of claim 12, wherein a feed rate of a peristaltic pump is 20 to 25r/min during the spray drying process.

17. The method according to claim 10, wherein the sulfuric acid solution is added dropwise.

18. The method of claim 17, wherein the dropping is carried out for 1 to 3 hours.

19. The method of claim 10, wherein the mixing time is 0.5 to 3 hours.

20. The process according to claim 10, wherein the aging time is 2 to 4 hours.

21. The method of claim 10, wherein the temperature of mixing, adding the sulfuric acid solution, and aging is each independently selected from 70-80 ℃.

22. The method as claimed in claim 10, wherein the mixing, adding and aging stirring rates are each independently selected from 200-400 r/min.

23. The method of claim 10, further comprising a post-filtration wash.

24. The method of claim 23, wherein the washing is washing until the filtrate has a conductivity of 0.1-1.0us/cm and a pH of 7-8.

25. The method of claim 10, comprising the steps of:

(1) mixing 5-8% concentration nanometer cellulose material dispersion liquid and 20-25% concentration sodium metasilicate solution at 70-80 deg.c and stirring speed of 200-400r/min for 0.5-3 hr, and dropping 12-20 wt% concentration sulfuric acid solution to pH 7-8 for 1-3 hr;

(2) stopping dropwise adding the sulfuric acid solution, aging for 2-4h, filtering and washing until the conductivity of the filtrate is 0.1-1.0us/cm and the pH is 7-8, and finally performing spray drying at the temperature of 150-180 ℃ to obtain the nano-silica doped nano-cellulose material.

26. Use of nanosilica doped nanocellulose material according to any of claims 1-9 as rubber reinforcement.

27. A modified rubber comprising the nanosilica-doped nanocellulose material of any of claims 1-9.

28. The modified rubber according to claim 27, wherein the modified rubber comprises the following components in parts by weight:

100 parts of rubber;

45-50 parts of nanosilica doped nanocellulose material of any of claims 1-9;

10-15 parts of an active agent;

1-2 parts of an anti-aging agent;

1-3 parts of an accelerator;

1-3 parts of sulfur.