Composite silicon dioxide as well as preparation method and application thereof

Abstract

The invention provides composite silicon dioxide as well as a preparation method and application thereof. The composite silicon dioxide is a combination of hydrophilic fumed silica and hydrophobic fumed silica, the mass of the hydrophobic fumed silica is 4wt%-8wt% of the mass of the hydrophilic fumed silica; the hydrophobic fumed silica is obtained by modifying the hydrophilic fumed silica. The surface of hydrophilic fumed silica is hydrophilic and oleophobic, so that the hydrophilic fumed silica is directly used for filling a rubber material and is difficult to play a reinforcing role of the rubber material; part of hydrophilic fumed silica needing to be added into a rubber material is modified into hydrophobic fumed silica, wettability, dispersity and interface bonding strength are improved, and the reinforcing effect of composite silica is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon dioxide preparation, and relates to silicon dioxide for tires, and in particular to composite silicon dioxide and a preparation method and application thereof. Background Art

[0002] Adding silica to tires can enhance rolling resistance, wear resistance, grip and other properties. Generally speaking, silica with a high specific surface area can improve the wear resistance of tires, but a larger specific surface area means increased interactions, which is not conducive to the mixing and dispersion of silica between rubber materials.

[0003] Compared with wet silica, the primary agglomerate of fumed silica has a smaller primary particle size and a larger specific surface area. Fumed silica includes hydrophilic fumed silica and hydrophobic fumed silica. Hydrophilic fumed silica has excellent properties such as large specific surface area, strong surface adsorption capacity, large surface energy, and good dispersion performance. It has good stability, reinforcement, thickening and thixotropy. When used in tire rubber materials, it can improve the wear resistance of tires.

[0004] For example, CN108043382A discloses a masterbatch, a method for producing the masterbatch, a rubber composition for a tire, a method for producing the rubber composition for a tire, and a rubber material for a tire, which uses hydrophilic fumed silica to improve wear resistance.

[0005] However, fumed silica with hydrophilic and oleophobic surface properties is difficult to disperse in rubber materials, which limits its performance. In order to improve the performance of hydrophilic fumed silica and increase the service life of tires, it is necessary to provide a composite silica and a preparation method thereof that can improve the depolymerization ability of silica, improve the wear resistance and service life of tires. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a composite silica and a preparation method and application thereof, wherein the composite silica has good wettability, dispersibility and interface bonding strength in rubber materials, can improve the wear resistance of rubber and increase the service life of tires.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a composite silica, wherein the composite silica is a combination of hydrophilic fumed silica and hydrophobic fumed silica;

[0009] The mass of the hydrophobic fumed silica is 4wt%-8wt% of the mass of the hydrophilic fumed silica;

[0010] The hydrophobic fumed silica is obtained by modifying the hydrophilic fumed silica.

[0011] Hydrophilic fumed silica has a large specific surface area, but the hydrophilic fumed silica prepared by the gas phase method has many residual silanol (Si-OH) and siloxy groups, which makes the surface of the hydrophilic fumed silica have a strong polarity; the surface of the hydrophilic fumed silica with strong polarity is hydrophilic and oleophobic, and it is difficult to play a modifying role when directly filled into the material; the present invention modifies part of the hydrophilic fumed silica that needs to be added to the rubber material into hydrophobic fumed silica, and improves the modification performance of the composite silica through the synergistic effect of the hydrophilic fumed silica and the hydrophobic fumed silica, so that when it is used in the rubber material, it can effectively reduce the endogenous heat and improve the wear resistance and service life of the rubber material.

[0012] Among them, controlling the appropriate ratio of hydrophilic fumed silica to hydrophobic fumed silica can improve the uniformity of its distribution in the rubber material without reducing the modification effect of the hydrophilic fumed silica. In the present invention, the mass of the hydrophobic fumed silica needs to be 4wt%-8wt% of the mass of the hydrophilic fumed silica, for example, it can be 4wt%, 5wt%, 6wt%, 7wt% or 8wt%, but is not limited to the listed values, and the remaining values ​​not listed in the numerical range are also applicable.

[0013] Preferably, the method for modifying the hydrophilic fumed silica to obtain the hydrophobic fumed silica comprises:

[0014] In an oxygen-free atmosphere, mixing hydrophilic fumed silica, a modifier and a solvent, performing a modification treatment, and obtaining the hydrophobic fumed silica;

[0015] The modifier includes dimethyldichlorosilane and 2-ethoxyethylamine.

[0016] The modifier used in the present invention includes dimethyldichlorosilane and 2-ethoxyethylamine, wherein dimethyldichlorosilane can undergo condensation reaction with the surface active hydroxyl groups of hydrophilic fumed silica, thereby increasing the steric hindrance between silica ions and achieving the purpose of improving its wettability, dispersibility and interface bonding strength; the use of 2-ethoxyethylamine can form hydrogen bonds by utilizing the reaction between amino groups and hydroxyl groups, thereby achieving the purpose of effectively preventing ion agglomeration and precipitation; the present invention uses the synergistic improvement effect of dimethyldichlorosilane and 2-ethoxyethylamine to make the obtained hydrophobic fumed silica synergistic with the hydrophilic fumed silica, so that when it is used in rubber materials, it can effectively reduce the internal heat and improve the wear resistance and service life of the rubber materials.

[0017] Preferably, the solvent comprises an organic solvent, preferably toluene.

[0018] Preferably, the mass of the modifier is 8wt%-10wt% of the hydrophilic fumed silica, for example, it can be 8wt%, 8.5wt%, 9wt%, 9.5wt% or 10wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the mass of the 2-ethoxyethylamine is 8wt%-12wt% of the mass of the dimethyldichlorosilane, for example, it can be 8wt%, 9wt%, 10wt%, 11wt% or 12wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] In a second aspect, the present invention provides a method for preparing the composite silicon dioxide as described in the first aspect, characterized in that the preparation method comprises the following steps:

[0021] (1) preparing hydrophilic fumed silica;

[0022] (2) modifying the hydrophilic fumed silica described in part of step (1) to obtain hydrophobic fumed silica;

[0023] (3) Mixing the hydrophilic fumed silica and the hydrophobic fumed silica according to the formula amount to obtain the composite silica.

[0024] The second aspect of the present invention provides a composite silica obtained by a preparation method, which improves the modification performance of the composite silica through the synergistic effect of hydrophilic fumed silica and hydrophobic fumed silica, so that when it is used in rubber materials, it can effectively reduce endogenous heat and improve the wear resistance and service life of the rubber material.

[0025] Preferably, the step of preparing hydrophilic fumed silica comprises:

[0026] Mixing silicon tetrachloride, hydrogen, oxygen and ozone to react and obtain the hydrophilic fumed silica;

[0027] The volume ratio of silicon tetrachloride, hydrogen, oxygen and ozone is 1:(1.5-2):(12-15):(1-2).

[0028] The volume ratio of silicon tetrachloride to hydrogen is 1:(1.5-2), for example, 1:1.5, 1:1.6, 1:1.8, 1:1.9 or 1:2, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] The volume ratio of silicon tetrachloride to oxygen is 1:(12-15), for example, it can be 1:12, 1:13, 1:14 or 1:15, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] The volume ratio of silicon tetrachloride to ozone is 1:(1-2), for example, 1:1, 1:1.2, 1:1.5, 1:1.8 or 1:2, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] When preparing hydrophilic fumed silica, the present invention uses ozone to increase the specific surface area of ​​the obtained hydrophilic fumed silica and reduce its tap density.

[0032] Preferably, the reaction temperature is 1700°C-1750°C, for example, 1700°C, 1710°C, 1720°C, 1740°C or 1750°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, the preparation method of the present invention further comprises a deacidification treatment after mixing according to the formula amount. The present invention does not further limit the specific operation of the deacidification treatment, as long as the deacidification treatment can be achieved.

[0034] Preferably, the hydrophilic fumed silica is modified to obtain the hydrophobic fumed silica comprising:

[0035] In an oxygen-free atmosphere, the hydrophilic fumed silica and the modifier are mixed and modified to obtain the hydrophobic fumed silica;

[0036] The modifier includes dimethyldichlorosilane and 2-ethoxyethylamine.

[0037] Preferably, the modification treatment is carried out at a temperature of 400°C-450°C and for a time of 3h-5h.

[0038] The temperature of the modification treatment in the present invention is 400°C-450°C, for example, it can be 400°C, 410°C, 420°C, 440°C or 450°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] The modification treatment time in the present invention is 3h-5h, for example, 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, the mass of the modifier is 8wt%-10wt% of the hydrophilic fumed silica, for example, it can be 8wt%, 8.5wt%, 9wt%, 9.5wt% or 10wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the mass of the 2-ethoxyethylamine is 8wt%-12wt% of the mass of the dimethyldichlorosilane, for example, it can be 8wt%, 9wt%, 10wt%, 11wt% or 12wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] Preferably, the gas used in the oxygen-free atmosphere includes nitrogen and / or an inert gas.

[0043] Preferably, the inert gas comprises any one of helium, neon or argon or a combination of at least two of them. Typical but non-limiting compositions include a combination of helium and neon, a combination of neon and argon, a combination of helium and argon, or a combination of helium, neon and argon.

[0044] In a third aspect, the present invention provides a use of the composite silica as described in the first aspect, wherein the composite silica is used as a reinforcing agent for tire rubber.

[0045] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] Hydrophilic fumed silica has a large specific surface area, but the hydrophilic fumed silica prepared by the gas phase method has many residual silanol (Si-OH) and siloxy groups, which makes the surface of the hydrophilic fumed silica have a strong polarity; the surface of the hydrophilic fumed silica with strong polarity is hydrophilic and oleophobic, and it is difficult to play a modifying role when directly filled into the material; the present invention modifies part of the hydrophilic fumed silica that needs to be added to the rubber material into hydrophobic fumed silica, and improves the modification performance of the composite silica through the synergistic effect of the hydrophilic fumed silica and the hydrophobic fumed silica, so that when it is used in the rubber material, it can effectively reduce the endogenous heat and improve the wear resistance and service life of the rubber material. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0049] This embodiment provides a composite silica, wherein the composite silica is a combination of hydrophilic fumed silica and hydrophobic fumed silica;

[0050] The mass of the hydrophobic fumed silica is 4-8wt% of the mass of the hydrophilic fumed silica;

[0051] The preparation method of the composite silicon dioxide described in this embodiment comprises the following steps:

[0052] (1) mixing silicon tetrachloride, hydrogen, oxygen and ozone in a volume ratio of 1:(1.5-2):(12-15):(1-2), reacting at a temperature of 1700° C. to 1750° C. to obtain hydrophilic fumed silica;

[0053] (2) Modifying the hydrophilic fumed silica obtained in part of step (1) to obtain hydrophobic fumed silica: mixing the hydrophilic fumed silica and the modifier under a nitrogen atmosphere, and performing a modification treatment at a temperature of 400° C. to 450° C. for 3 h to 5 h to obtain hydrophobic fumed silica;

[0054] The modifier includes dimethyldichlorosilane and 2-ethoxyethylamine, the mass of the modifier is 8wt%-10wt% of the hydrophilic fumed silica, and the mass of the 2-ethoxyethylamine is 8wt%-12wt% of the mass of the dimethyldichlorosilane;

[0055] (3) Mixing the hydrophilic fumed silica and the hydrophobic fumed silica according to the formula amount to obtain the composite silica.

[0056] Example 1

[0057] This embodiment provides a composite silica, wherein the composite silica is a combination of hydrophilic fumed silica and hydrophobic fumed silica;

[0058] The mass of the hydrophobic fumed silica is 6wt% of the mass of the hydrophilic fumed silica;

[0059] The preparation method of the composite silicon dioxide described in this embodiment comprises the following steps:

[0060] (1) mixing silicon tetrachloride, hydrogen, oxygen and ozone in a volume ratio of 1:1.8:14:1.5, reacting at a temperature of 1720° C. to obtain hydrophilic fumed silica;

[0061] (2) Modifying the hydrophilic fumed silica obtained in part of step (1) to obtain hydrophobic fumed silica: mixing the hydrophilic fumed silica and the modifier under a nitrogen atmosphere, and performing a modification treatment at a temperature of 420° C. for 4 hours to obtain hydrophobic fumed silica;

[0062] The modifier includes dimethyldichlorosilane and 2-ethoxyethylamine, the mass of the modifier is 9wt% of the hydrophilic fumed silica, and the mass of the 2-ethoxyethylamine is 10wt% of the mass of the dimethyldichlorosilane;

[0063] (3) Mixing the hydrophilic fumed silica and the hydrophobic fumed silica according to the formula amount to obtain the composite silica.

[0064] Example 2

[0065] This embodiment provides a composite silica, wherein the composite silica is a combination of hydrophilic fumed silica and hydrophobic fumed silica;

[0066] The mass of the hydrophobic fumed silica is 4wt% of the mass of the hydrophilic fumed silica;

[0067] The preparation method of the composite silicon dioxide described in this embodiment comprises the following steps:

[0068] (1) mixing silicon tetrachloride, hydrogen, oxygen and ozone in a volume ratio of 1:1.5:12:1, reacting at a temperature of 1700° C. to obtain hydrophilic fumed silica;

[0069] (2) Modifying the hydrophilic fumed silica obtained in part of step (1) to obtain hydrophobic fumed silica: mixing the hydrophilic fumed silica and the modifier under a nitrogen atmosphere, and performing a modification treatment at a temperature of 400° C. for 5 hours to obtain hydrophobic fumed silica;

[0070] The modifier includes dimethyldichlorosilane and 2-ethoxyethylamine, the mass of the modifier is 8wt% of the hydrophilic fumed silica, and the mass of the 2-ethoxyethylamine is 8wt% of the mass of the dimethyldichlorosilane;

[0071] (3) Mixing the hydrophilic fumed silica and the hydrophobic fumed silica according to the formula amount to obtain the composite silica.

[0072] Example 3

[0073] This embodiment provides a composite silica, wherein the composite silica is a combination of hydrophilic fumed silica and hydrophobic fumed silica;

[0074] The mass of the hydrophobic fumed silica is 8wt% of the mass of the hydrophilic fumed silica;

[0075] The preparation method of the composite silicon dioxide described in this embodiment comprises the following steps:

[0076] (1) mixing silicon tetrachloride, hydrogen, oxygen and ozone in a volume ratio of 1:2:15:2, and reacting at a temperature of 1750° C. to obtain hydrophilic fumed silica;

[0077] (2) Modifying the hydrophilic fumed silica obtained in part of step (1) to obtain hydrophobic fumed silica: mixing the hydrophilic fumed silica and the modifier under a nitrogen atmosphere, and performing a modification treatment at a temperature of 450° C. for 3 hours to obtain hydrophobic fumed silica;

[0078] The modifier includes dimethyldichlorosilane and 2-ethoxyethylamine, the mass of the modifier is 10wt% of the hydrophilic fumed silica, and the mass of the 2-ethoxyethylamine is 12wt% of the mass of the dimethyldichlorosilane;

[0079] (3) Mixing the hydrophilic fumed silica and the hydrophobic fumed silica according to the formula amount to obtain the composite silica.

[0080] Example 4

[0081] This embodiment provides a composite silica, which is the same as that of embodiment 1 except that the mass of the modifier is 6 wt % of the hydrophilic fumed silica when preparing the composite silica.

[0082] Example 5

[0083] This embodiment provides a composite silica, which is the same as that of embodiment 1 except that the mass of the modifier is 12 wt % of the hydrophilic fumed silica when preparing the composite silica.

[0084] Example 6

[0085] This embodiment provides a composite silica, which is the same as that of Embodiment 1 except that when preparing the composite silica, the mass of 2-ethoxyethylamine is 6wt% of the mass of the dimethyldichlorosilane.

[0086] Example 7

[0087] This embodiment provides a composite silica, which is the same as that of Embodiment 1 except that when preparing the composite silica, the mass of 2-ethoxyethylamine is 15wt% of the mass of the dimethyldichlorosilane.

[0088] Example 8

[0089] This embodiment provides a composite silica, which is the same as that of Embodiment 1 except that ozone is not used when preparing the hydrophilic fumed silica.

[0090] Comparative Example 1

[0091] This comparative example provides a composite silica, which is the same as Example 1 except that the mass of the hydrophobic fumed silica is 2 wt % of the mass of the hydrophilic fumed silica.

[0092] Comparative Example 2

[0093] This comparative example provides a composite silica, which is the same as Example 1 except that the mass of the hydrophobic fumed silica is 10wt% of the mass of the hydrophilic fumed silica.

[0094] Comparative Example 3

[0095] This comparative example provides the hydrophilic fumed silica in Example 1.

[0096] Performance Characterization

[0097] The silica obtained in the above examples and comparative examples was prepared into a rubber composition:

[0098] The rubber was mixed according to GB / T 41938-2022 “Evaluation method for precipitated hydrated silica as a rubber compounding agent in a mixture of solution polymerized styrene-butadiene rubber (S-SBR) and butadiene rubber (BR)”.

[0099] According to GB / T9867-2008 "Determination of wear resistance of vulcanized rubber or thermoplastic rubber (rotating roller abrasion machine method"), the wear resistance of rubber is tested. The wear resistance index is:

[0100] Wear resistance index = measured wear amount / wear amount of the corresponding rubber composition in Example 1

[0101] The results are shown in Table 1.

[0102] Table 1

[0103] Wear resistance index Example 1 1 Example 2 1.08 Example 3 0.95 Example 4 1.29 Example 5 1.15 Example 6 1.20 Example 7 1.17 Example 8 1.31 Comparative Example 1 1.32 Comparative Example 2 1.20 Comparative Example 3 1.56

[0104] In summary, the present invention modifies part of the hydrophilic fumed silica that needs to be added to the rubber material into hydrophobic fumed silica. Through the synergistic effect of the hydrophilic fumed silica and the hydrophobic fumed silica, the modified performance of the composite silica is improved, so that when it is used in the rubber material, it can effectively reduce the endogenous heat and improve the wear resistance and service life of the rubber material.

[0105] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite silicon dioxide, characterized in that The composite silica is a combination of hydrophilic fumed silica and hydrophobic fumed silica; The mass of the hydrophobic fumed silica is 4wt%-8wt% of the mass of the hydrophilic fumed silica; The hydrophobic fumed silica is obtained by modifying the hydrophilic fumed silica.

2. The composite silicon dioxide according to claim 1, characterized in that The method for modifying the hydrophilic fumed silica to obtain the hydrophobic fumed silica comprises: In an oxygen-free atmosphere, mixing hydrophilic fumed silica, a modifier and a solvent, performing a modification treatment, and obtaining the hydrophobic fumed silica; The modifier includes dimethyldichlorosilane and 2-ethoxyethylamine.

3. The composite silicon dioxide according to claim 2, characterized in that The mass of the modifier is 8wt%-10wt% of the hydrophilic fumed silica; Preferably, the mass of the 2-ethoxyethylamine is 8wt%-12wt% of the mass of the dimethyldichlorosilane.

4. A method for preparing the composite silicon dioxide according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) preparing hydrophilic fumed silica; (2) modifying the hydrophilic fumed silica described in part of step (1) to obtain hydrophobic fumed silica; (3) Mixing the hydrophilic fumed silica and the hydrophobic fumed silica according to the formula amount to obtain the composite silica.

5. The preparation method according to claim 4, characterized in that: The steps of preparing hydrophilic fumed silica include: Mixing silicon tetrachloride, hydrogen, oxygen and ozone to react and obtain the hydrophilic fumed silica; The volume ratio of silicon tetrachloride, hydrogen, oxygen and ozone is 1:(1.5-2):(12-15):(1-2).

6. The preparation method according to claim 5, characterized in that: The reaction temperature is 1700°C-1750°C.

7. The preparation method according to claim 4, characterized in that: The hydrophilic fumed silica is modified to obtain the hydrophobic fumed silica comprising: In an oxygen-free atmosphere, the hydrophilic fumed silica and the modifier are mixed and modified to obtain the hydrophobic fumed silica; The modifier includes dimethyldichlorosilane and 2-ethoxyethylamine.

8. The preparation method according to claim 7, characterized in that: The temperature of the modification treatment is 400°C-450°C, and the time is 3h-5h; Preferably, the mass of the modifier is 8wt%-10wt% of the hydrophilic fumed silica; Preferably, the mass of the 2-ethoxyethylamine is 8wt%-12wt% of the mass of the dimethyldichlorosilane.

9. The preparation method according to claim 7, characterized in that: The gas used in the oxygen-free atmosphere includes nitrogen and / or an inert gas; Preferably, the inert gas includes any one of helium, neon or argon, or a combination of at least two of them.

10. A use of the composite silicon dioxide according to any one of claims 1 to 3, characterized in that: The composite silica is used as a reinforcing agent for tire rubber.