阅读说明：本技术 一种低滚阻抗湿滑改性天然橡胶复合材料及其制备方法 (Low rolling resistance wet-skid modified natural rubber composite material and preparation method thereof ) 是由 张志毅 张利召 刘亚青 赵贵哲 于 2021-01-28 设计创作，主要内容包括：本发明涉及改性天然橡胶复合材料,具体涉及一种低滚阻抗湿滑改性天然橡胶复合材料及其制备方法；包括如下步骤：使用硅烷偶联剂KH792改性二氧化硅制得氨基化二氧化硅；然后使用巯基-烯点击化学法将半胱氨酸接枝在溶聚丁苯橡胶上,制得羧基功能化的丁苯橡胶；将氨基化的二氧化硅与羧基化的丁苯橡胶通过酰胺化反应形成共价键连接,然后将制得的改性粒子分散到蒸馏水中再与天然橡胶共混后硫化,制得改性天然橡胶复合材料；本发明采用快速有效的混合方式,改性后的二氧化硅在天然橡胶基体中能够较好地分散并且能够与基体形成共价键连接,得到的天然橡胶复合材料具有良好的抗湿滑性能和较低的滚动阻力。(The invention relates to a modified natural rubber composite material, in particular to a low rolling resistance wet-skid modified natural rubber composite material and a preparation method thereof; the method comprises the following steps: modifying the silicon dioxide by using a silane coupling agent KH792 to prepare aminated silicon dioxide; then grafting cysteine on the solution polymerized styrene-butadiene rubber by using a sulfydryl-alkene click chemistry method to prepare carboxyl functionalized styrene-butadiene rubber; forming covalent bond connection between aminated silicon dioxide and carboxylated styrene-butadiene rubber through amidation reaction, dispersing the prepared modified particles into distilled water, blending the modified particles with natural rubber, and vulcanizing to prepare a modified natural rubber composite material; the invention adopts a quick and effective mixing mode, the modified silicon dioxide can be well dispersed in a natural rubber matrix and can form covalent bond connection with the matrix, and the obtained natural rubber composite material has good wet skid resistance and lower rolling resistance.)

1. The low rolling resistance wet-skid modified natural rubber composite material is characterized by being prepared from the following raw materials in parts by mass: 100 parts of natural rubber, 20-50 parts of modified silica nanoparticles and 12.5 parts of rubber auxiliaries;

the modified silicon dioxide nano particle is prepared by the following steps:

(1) modifying the silica by using a silane coupling agent KH792 to obtain aminated silica particles;

(2) grafting cysteine on styrene-butadiene rubber by a sulfydryl-alkene click chemistry method to obtain carboxyl functionalized styrene-butadiene rubber;

(3) forming covalent bond connection between the aminated silicon dioxide and the carboxyl functionalized styrene butadiene rubber through amidation reaction, and then obtaining the modified silicon dioxide nano particles through suction filtration, washing and drying.

2. The low rolling resistance wet skid modified natural rubber composite material as claimed in claim 1, wherein the specific preparation method of the aminated silica particles is as follows:

(1) mixing a silane coupling agent KH792, distilled water and ethanol according to a mass ratio of 1:1:8, standing for 2 hours to fully hydrolyze the KH792, and obtaining a silane coupling agent hydrolysate;

(2) weighing silicon dioxide, pouring the silicon dioxide into a solution with the ratio of ethanol to distilled water being 3:1, and uniformly stirring by ultrasonic waves, wherein the mass ratio of the silicon dioxide to the ethanol to the distilled water solution is 1: 9;

(3) and (3) slowly dripping the uniformly mixed dispersion liquid obtained in the step (2) into the silane coupling agent hydrolysate prepared in the step (1), reacting for 2 hours at 80 ℃, and performing suction filtration, washing and drying to obtain the aminated silicon dioxide particles.

3. The wet skid resistance-modified natural rubber composite material as claimed in claim 2, wherein the silane coupling agent KH792 is used in an amount of 8% by mass of silica.

4. The low rolling resistance wet skid modified natural rubber composite material as claimed in claim 1, wherein the specific preparation method of the carboxyl functionalized styrene butadiene rubber is as follows: preparing cysteine into 3mg/ml aqueous solution, adding the aqueous solution into solution polymerized butadiene styrene rubber solution with the solid content of 20%, adding 25g/L lauroyl peroxide as a catalyst, and adding N₂Reacting for 1h at 80 ℃ in the atmosphere to obtain the carboxyl functionalized styrene butadiene rubber.

5. The low rolling resistance wet skid modified natural rubber composite as claimed in claim 1, wherein the mass ratio of cysteine to styrene butadiene rubber is 1:50, and the mass ratio of styrene butadiene rubber to lauroyl peroxide is 3000: 1.

6. The low rolling resistance wet skid modified natural rubber composite material as claimed in claim 1, wherein the specific reaction process of the aminated silica particles and the carboxylic functionalized styrene-butadiene rubber is as follows: adding a carboxyl activating agent 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and a catalyst N-hydroxysuccinimide into a carboxyl functionalized styrene-butadiene rubber solution, standing for half an hour, slowly dropwise adding an aminated silicon dioxide aqueous solution with the concentration of 10%, and reacting for 24 hours at 0 ℃ after dropwise adding.

7. The low rolling resistance wet skid modified natural rubber composite of claim 6, wherein the mass ratio of the aminated silica particles to the carboxylic functionalized styrene-butadiene rubber is 1: 20.

8. The low rolling resistance wet-skid modified natural rubber composite material as claimed in claim 1, wherein the rubber auxiliary agent is composed of the following raw materials in parts by mass: 5 parts of zinc oxide, 2 parts of stearic acid, 1 part of anti-aging agent 4010NA, 1 parts of antioxidant RD, 1.5 parts of accelerator NOBS and 2 parts of sulfur.

9. The method for preparing a low rolling resistance wet skid modified natural rubber composite as claimed in any one of claims 1 to 8, comprising the steps of:

adding modified silicon dioxide particles in parts by mass into distilled water to prepare suspension with the concentration of 10%, performing ultrasonic treatment for 15min, adding the suspension into natural latex with the solid content of 20%, and mechanically stirring for 30 min; then demulsifying by using a 10% calcium chloride solution, and drying in a vacuum drying oven at 70 ℃ to constant weight to obtain a master batch;

plasticating the dry master batch obtained in the step I in an internal mixer at the temperature of 90 ℃ and the speed of 40rpm, sequentially adding 5 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 1.5 parts by mass of a vulcanization accelerator NOBS, 1 part by mass of an anti-aging agent 4010NA and 1 part by mass of an antioxidant RD, mixing for 5min, and discharging rubber mixed batch;

thirdly, adjusting the temperature of a die cavity of the internal mixer to 110 ℃, putting the rubber compound obtained in the second step into the internal mixer, mixing for 5min, and then discharging again;

cooling the rubber material obtained in the step (c) to room temperature, transferring the rubber material to an open mill for further mixing, adding 2 parts by mass of sulfur in the mixing process, and mixing the rubber material uniformly; taking out, standing for 24h, and then hot-pressing for 15min at 150 ℃ on a flat vulcanizing machine for vulcanization to obtain the natural rubber composite material.

Technical Field

The invention relates to a modified natural rubber composite material, in particular to a low rolling resistance wet-skid modified natural rubber composite material and a preparation method thereof.

Background

With the implementation of the eu tire labeling method, the standard of green performance is clarified, and the research on green tires is driven to a high tide. The green tire designed by new materials, new technologies and new formulas inherits the green manufacturing concept and wins the favor of people by the characteristic of high-efficiency application. The raw materials and the production process of the green tire follow the green manufacturing concept, the scientific development concept of energy conservation, emission reduction and environmental protection is practiced in the application process, and the green tire is a novel tire which accords with the socialized sustainable development. Therefore, developing green tires is one of the leading trends in the tire industry in the future. The green tire is characterized by mainly comprising: (1) the rolling resistance of the tire is low, so that fuel oil is saved, carbon dioxide emission is reduced, haze caused by automobile exhaust is reduced, and the reduction of atmospheric pollution and environmental protection are facilitated; (2) the tire has good wet skid resistance and good handling performance, and the driving safety is improved.

At present, in the process of developing and manufacturing high-performance tires, the method of reinforcing natural rubber by carbon black is difficult to regulate and control the rolling resistance performance and the wet skid resistance performance, and can not meet the requirements of the current society. Therefore, it is still a great challenge to effectively improve the wet skid resistance of the tread rubber material and reduce the rolling resistance.

Silica, also known as white carbon, is the most preferred filler to replace carbon black in the green tire manufacturing process due to its smaller particle size, higher hardness, and more surface functional groups. According to the current research, the silica is used as a reinforcing filler, so that the wet skid resistance of the tire can be improved, and the rolling resistance of the tire can be effectively reduced. However, the silica is easily agglomerated due to more hydroxyl groups on the surface, which affects the reinforcing effect, and the interface interaction between the silica and the rubber matrix is weak. Therefore, how to improve the dispersion of silica in the natural rubber matrix and enhance the interfacial interaction between the filler and the matrix becomes the key for improving the rubber performance of silica.

Disclosure of Invention

The invention overcomes the defects of the prior art and provides the low rolling resistance wet-skid modified natural rubber composite material, thereby complementing the defects in the field at present and meeting the development requirements of high-performance tires.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the low rolling resistance wet-skid modified natural rubber composite material is prepared from the following raw materials in parts by mass: 100 parts of natural rubber, 20-50 parts of modified silica nanoparticles and 12.5 parts of rubber auxiliaries;

the modified silicon dioxide nano particle is prepared by the following steps:

(1) modifying silica with a silane coupling agent N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane (KH792) to obtain aminated silica particles;

(2) grafting cysteine on styrene-butadiene rubber by a sulfydryl-alkene click chemistry method to obtain carboxyl functionalized styrene-butadiene rubber;

(3) forming covalent bond connection between the aminated silicon dioxide and the carboxyl functionalized styrene butadiene rubber through amidation reaction, and then obtaining the modified silicon dioxide nano particles through suction filtration, washing and drying.

The modification mechanism of the silica nanoparticles of the present invention is:

(1)

(2)

(3)

further, the specific preparation method of the aminated silica particle comprises the following steps:

(1) mixing a silane coupling agent KH792, distilled water and ethanol according to a mass ratio of 1:1:8, standing for 2 hours to fully hydrolyze the KH792, and obtaining a silane coupling agent hydrolysate;

(2) weighing silicon dioxide, pouring the silicon dioxide into a solution with the ratio of ethanol to distilled water being 3:1, and uniformly stirring by ultrasonic waves, wherein the mass ratio of the silicon dioxide to the ethanol to the distilled water solution is 1: 9;

(3) and (3) slowly dripping the uniformly mixed dispersion liquid obtained in the step (2) into the silane coupling agent hydrolysate prepared in the step (1), reacting for 2 hours at 80 ℃, and performing suction filtration, washing and drying to obtain the aminated silicon dioxide particles.

Further, the amount of the silane coupling agent KH792 is 8% of the mass of the silica.

Further, the concrete preparation method of the carboxyl functionalized styrene butadiene rubber comprises the following steps: preparing cysteine into 3mg/ml aqueous solution, adding the aqueous solution into solution polymerized butadiene styrene rubber solution with the solid content of 20%, adding 25g/L lauroyl peroxide as a catalyst, and adding N₂Reacting for 1h at 80 ℃ in the atmosphere to obtain the carboxyl functionalized styrene butadiene rubber.

Preferably, the mass ratio of the cysteine to the styrene-butadiene rubber is 1:50, and the mass ratio of the styrene-butadiene rubber to the lauroyl peroxide is 3000: 1.

Further, the specific reaction process of the aminated silica particles and the carboxyl functionalized styrene-butadiene rubber is as follows: adding a carboxyl activating agent 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and a catalyst N-hydroxysuccinimide into a carboxyl functionalized styrene-butadiene rubber solution, standing for half an hour, slowly dropwise adding an aminated silicon dioxide aqueous solution with the concentration of 10%, and reacting for 24 hours at 0 ℃ after dropwise adding.

Preferably, the mass ratio of the aminated silica particles to the carboxyl-functionalized styrene-butadiene rubber is 1: 20.

Further, the rubber auxiliary agent is composed of the following raw materials in parts by mass: 5 parts of zinc oxide, 2 parts of stearic acid, 1 part of anti-aging agent 4010NA, 1 parts of antioxidant RD, 1.5 parts of accelerator NOBS and 2 parts of sulfur.

In addition, the invention also provides a preparation method of the low rolling resistance wet-skid modified natural rubber composite material, which comprises the following steps:

adding modified silicon dioxide particles in parts by mass into distilled water to prepare suspension with the concentration of 10%, performing ultrasonic treatment for 15min, adding the suspension into natural latex with the solid content of 20%, and mechanically stirring for 30 min; then demulsifying by using a 10% calcium chloride solution, and drying in a vacuum drying oven at 70 ℃ to constant weight to obtain a master batch;

plasticating the dry master batch obtained in the step I in an internal mixer at the temperature of 90 ℃ and the speed of 40rpm, sequentially adding 5 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 1.5 parts by mass of a vulcanization accelerator NOBS, 1 part by mass of an anti-aging agent 4010NA and 1 part by mass of an antioxidant RD, mixing for 5min, and discharging rubber mixed batch;

thirdly, adjusting the temperature of a die cavity of the internal mixer to 110 ℃, putting the rubber compound obtained in the second step into the internal mixer, mixing for 5min, and then discharging again;

cooling the rubber material obtained in the step (c) to room temperature, transferring the rubber material to an open mill for further mixing, adding 2 parts by mass of sulfur in the mixing process, and mixing the rubber material uniformly; taking out, standing for 24h, and then hot-pressing for 15min at 150 ℃ on a flat vulcanizing machine for vulcanization to obtain the natural rubber composite material.

The natural rubber is natural latex crude rubber, and the styrene butadiene rubber is solution polymerized styrene butadiene rubber.

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

by functionalizing silica with a silane coupling agent in advance, not only the particle diameter of silica can be reduced, but also a desired functional group can be obtained on the surface thereof; subsequent amidation reactions enable covalent bonding between the silica and the substrate; and finally, uniformly dispersing the silicon dioxide in the natural rubber matrix in an effective mixing mode, thereby preparing the low rolling resistance wet-skid modified natural rubber composite material. The composite material has good wet skid resistance and lower rolling resistance, when the content of the modified silicon dioxide is 40 parts measured by a dynamic mechanical property analyzer, the loss factor value at 0 ℃ is 0.116, the loss factor value at 60 ℃ is 0.023, and the tensile strength measured by a universal test stretcher is 23.5 MPa. Compared with natural rubber, the wet skid resistance is improved by 41 percent, the rolling resistance is reduced by 36 percent, and the tensile strength is improved by 16 percent.

Drawings

Fig. 1 is SEM photographs of unmodified (a) and modified (b) silica particles.

Fig. 2 is an infrared spectrum of modified silica nanoparticles.

Fig. 3 is a thermogravimetric plot of modified silica nanoparticles.

FIG. 4 is an SEM photograph of a low roll resistance wet skid modified natural rubber composite prepared according to an example of the present invention.

FIG. 5 is an EDS chart of a low roll resistance wet skid modified natural rubber composite prepared in accordance with an example of the present invention, showing that: the modified silica particles are uniformly dispersed in the matrix natural rubber.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto, and may be carried out with reference to conventional techniques for process parameters not particularly noted.

Preparing modified silicon dioxide particle powder:

3.2g of silane coupling agent KH792 is weighed, slowly dripped into a blended solution of 3.2g of distilled water and 25.6g of ethanol, stirred by ultrasound for 15min and then kept stand for 2h for sufficient hydrolysis for later use. Then weighing 40g of silicon dioxide, pouring the silicon dioxide into 360g of solution with the ratio of ethanol to distilled water being 3:1, stirring the solution ultrasonically for 30min, pouring the solution into a three-neck flask, slowly dripping the prepared silane coupling agent hydrolysate, reacting the mixture for 2h in a water bath kettle at the temperature of 80 ℃, and finally obtaining the aminated silicon dioxide powder through suction filtration, washing and drying.

Preparing 0.6g cysteine into 3mg/ml aqueous solution, adding the solution into 150g solution of solution polymerized butadiene styrene rubber with solid content of 20%, adding 0.4ml 25g/L lauroyl peroxide as catalyst, and adding N in a water bath kettle₂Reacting for 1h at the temperature of 80 ℃ in the atmosphere to obtain the carboxyl functionalized styrene butadiene rubber.

Adding 0.03g of EDC and 0.02g of NHS of a carboxyl activating agent into a carboxyl functionalized styrene-butadiene rubber solution, stirring for 10min, standing for half an hour, slowly dropwise adding into a prepared aminated silicon dioxide aqueous solution with the concentration of 10%, reacting for 24h at 0 ℃, and performing suction filtration, washing and drying to obtain modified silicon dioxide powder.

Examples 1-4 preparation of low roll resistance wet skid modified natural rubber composites:

the following procedure was used to prepare the formulations according to table 1:

firstly, preparing the prepared modified silicon dioxide particles with the mass ratio into an aqueous solution, adding the aqueous solution into natural latex with the solid content of 60 percent after ultrasonic treatment for 15min, mechanically stirring the natural latex for 30min, and demulsifying the natural latex by using a calcium chloride solution. Drying in an oven at 70 ℃ to obtain a master batch;

plasticating the dry master batch obtained in the step I in an internal mixer at the temperature of 90 ℃ and the speed of 40rpm, sequentially adding 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1.5 parts by weight of vulcanization accelerator NOBS, 1 part by weight of anti-aging agent 4010NA and 1 part by weight of antioxidant RD, mixing for 5min, and discharging rubber mixed batch;

thirdly, adjusting the temperature of a die cavity of the internal mixer to 110 ℃, putting the rubber compound obtained in the second step into the internal mixer, mixing for 5min, and then discharging again;

cooling the rubber material obtained in the step (III) to room temperature, transferring the rubber material to an open mill for further mixing, adding sulfur with the mass fraction of 2% in the mixing process, and mixing the rubber material uniformly; taking out and standing for 24h, and then carrying out hot pressing on a flat vulcanizing machine at 150 ℃ for 15min for vulcanization to obtain the vulcanized rubber. Examples rubber formulations are shown in table 1.

TABLE 1 rubber formulation (raw material content unit: parts by weight)

The rubber composite material was prepared according to the above formulation with 40 parts by weight of unmodified silica as a comparative example.

TABLE 2 mechanical Properties of comparative examples and examples 1 to 4

Sample (I)	Comparative example	Example 3	Example 1	Example 2	Example 4
						Tensile strength/MPa	17.5	20.3	17.8	18.1	19.4
Elongation at break/%	653.1	648.4	672.3	660.8	640.1
						Tear Strength/MPa	30.8	36.4	32.5	33.9	35.2

TABLE 3 dynamic mechanical Properties of comparative examples and examples 1 to 4

Sample (I)	Comparative example	Example 3	Example 1	Example 2	Example 4
						0℃tanδ	0.068	0.116	0.074	0.082	0.104
60℃tanδ	0.036	0.023	0.034	0.031	0.032

The comparative example and the vulcanized rubber composite materials obtained in examples 1 to 4 were subjected to the performance test, and the results are shown in tables 2 and 3. As can be seen from the test results in Table 2, the combination of mechanical properties is the best when 40 parts of modified silica is added. As can be seen from the results of the dynamic mechanical properties test in Table 3, example 3, i.e., 40 parts of modified silica, has the highest tan. delta. value at 0 ℃ and the lowest tan. delta. value at 60 ℃. The higher the tan delta test value at 0 ℃, the better the wet skid resistance is; the lower the tan delta value at 60 ℃ is, the lower the rolling resistance is. Therefore, when 40 parts of modified silica is added by using the method disclosed by the invention, the rubber composite material has good mechanical property, better wet skid resistance and lower rolling resistance.