KR101046340B1 - Method for preparing carbon black / silica composite using sol-gel method - Google Patents

Abstract

The present invention relates to a method for producing a carbon black / silica composite by synthesizing silica on the surface of carbon black, and more specifically, tetraethyl orthosilicate (TEOS) on the surface of carbon black particles stabilized by PVP (Polyvinylpyrrolidone) physically adsorbed And a method for preparing a carbon black / silica composite by combining silica synthesized from the same. According to the present invention, since the carbon black / silica composite can be prepared without chemically modifying the surface of the carbon black particles, the process is simplified, the processing time can be shortened, and can be usefully used in various applications. In the existing rubber industry process, it is possible to solve the problem of dispersion and dust in the polymer of carbon black and silica that occur in the compounding process can be particularly useful in the rubber industry.

Carbon Black / Silica Composite, TEOS, PVP, Sol-Gel Method, Polymer Grafting Method

Description

Method for producing carbon black / silica composites using sol-gel method {Production of Carbon black / Silica Composites by Sol-gel Process}

The present invention relates to a method for producing a carbon black / silica composite by synthesizing silica on a carbon black surface, and more specifically, by using TEOS (Tetraethyl orthosilicate) on the carbon black surface stabilized by adsorption of polyvinylpyrrolidone (PVP) It relates to a method for producing and bonding silica particles by the sol-gel method.

Carbon black is characterized by heat resistance, weather resistance, electrical conductivity and thermal conductivity, and these characteristics are important inorganic particles used throughout the industry as a reinforcing agent, pigment, and conductive material. However, the carbon black particles have a strong van der Waals force, which causes serious aggregation of the particles. Therefore, in order to overcome the limitations of the mechanical method in dispersing the carbon black in the polymer resin and to maximize the compatibility and to enhance the reinforcing effect, a method of grafting the polymer on the surface of the carbon black is widely used [ Prog. Polym. Sci. , 17, 417, 1992; J. Mater. Sci. , 33, 1871, 1998; Polym. Adv. Technol. , 12, 596, 2001]. As a method for producing such a polymer composite, heterogeneous polymerization methods such as suspension polymerization, dispersion polymerization and emulsion polymerization are mainly used. To this end, another chemical treatment, such as an acid treatment and a coupling agent, is required to attach a functional group, such as a carbon-carbon double bond, on which the reaction can begin on the carbon black surface. Therefore, the process is difficult and there is a disadvantage that the yield is not high in the entire reaction. For example, according to Korean Patent Application No. 0021053, in the production of silica / carbon nanotube composites, a hydroxyl group is introduced to the surface of the carbon nanotubes by chemical surface treatment, and then a silane coupling agent having an amine group is added to the hydroxyl. It is known to introduce silica by reacting with a practical group to introduce an active point therefrom.

On the other hand, carbon black used for the reinforcement and conductivity of the silicone rubber is to attach a silica having the same properties as that of the silicon, not the polymer, on the surface of the silicone rubber was intended to appear more robust reinforcement. Kazuhiro Fujiki used a method of synthesizing silica after polymer grafting, which is a conventional chemical method [ J. Mater. Sci. , 33, 1871, 1998].

However, there is no known example of synthesizing and bonding silica by sol-gel method using TEOS on the surface of carbon black particles stabilized by physically adsorbing PVP without chemically synthesizing polymer on the surface of carbon black by chemical method.

An object of the present invention is to provide a method for producing a carbon black / silica composite in which silica is bonded to the surface of the carbon black particles through a simple process.

In order to achieve the above object, the present invention is a step of physically adsorbing PVP on the surface of the carbon black particles, and bonding the silica synthesized by the sol-gel process from TEOS to the carbon black particles stabilized by the adsorption It provides a method for producing a carbon black / silica composite comprising a.

According to the present invention, since the carbon black / silica composite can be prepared without chemically modifying the surface of the carbon black particles, the process is simplified, the processing time can be shortened, and can be usefully used in various applications. In the existing rubber industry process, it is possible to solve the problem of dispersion and dust in the polymer of carbon black and silica that occur in the compounding process can be particularly useful in the rubber industry.

The present invention adsorbs polyvinylpyrrolidone (PVP) on the surface of carbon black particles, and then combines silica synthesized from TEOS to carbon black particles stabilized by PVP adsorption to prepare carbon black / silica composites. Provide a way to.

Hereinafter, the present invention will be described in detail step by step.

Method for producing a carbon black / silica composite according to the present invention

Adsorbing PVP on the carbon black surface in distilled water solvent (step 1);

Dispersing carbon black particles having PVP adsorbed in a mixed solvent of ethanol and ammonia water (step 2);

Synthesizing TEOS to silica by sol-gel method in the mixed solvent (step 3); And

Bonding the synthesized silica to the surface of the carbon black adsorbed PVP (step 4)

It includes.

In step 1, the PVP is preferably 0.075 to 0.375 parts by weight based on 100 parts by weight of distilled water. If the amount is less than 0.075 parts by weight, silica particles are not generated on the surface of the carbon black particles and are separately synthesized on the medium. When the amount is more than 0.375 parts by weight, the excess PVP increases the viscosity of the reactant, so that filtering for the next step is performed. There is no problem.

In step 1, PVP is physically adsorbed with the carbon black particles, so there is no need to chemically modify the surface of the carbon black particles. This simplifies the process and shortens the process time as compared to the conventional polymer grafting method.

In Step 2, the carbon black particles stabilized by PVP adsorption are dispersed in a mixed solvent of ethanol and ammonia water. In order to react with silica formed by the sol-gel method from TEOS in the following step 3, it is preferable to disperse the carbon black particles in the mixed solvent in advance. The ammonia water in this step is preferably used a solution containing about 25 to 30% NH ₃ , it is preferable to use 4 to 5 parts by volume with respect to 100 parts by volume of ethanol.

In step 3, TEOS is synthesized in silica in the mixed solvent. The silica synthesized in this step is rich in hydroxyl group, so that the bonding is facilitated by nitrogen bonding with hydrogen atoms and electrical attraction on the PVP chain adsorbed onto the carbon black particles in the subsequent step 4. The amount of TEOS in this step is preferably in the range of 3 to 7 parts by volume, more preferably in the range of 3 to 5 parts by volume with respect to 100 parts by volume of ethanol. If the amount of TEOS is less than 3 parts by volume, there is a problem that the silica is not synthesized normally, when exceeding 7 parts by volume excess silica is formed on the surface of the carbon black to disperse the composite in the polymer of the carbon black There is a problem that can not be achieved characteristics.

In step 4, the PVP-adsorbed carbon black particles present in the same mixed solvent and silica synthesized from TEOS are combined. More specifically, the nitrogen atoms in the PVP chain adsorbed on the surface of the carbon black particles bind to the synthesized silica rich in hydroxyl groups through hydrogen bonding and electrical attraction.

The above steps are preferably carried out in a temperature range of 20 to 50 ℃, more preferably carried out at 20 to 30 ℃. When the above steps are performed at a temperature below 20 ° C., excessive time is required for dissolution of PVP, adsorption of PVP on the surface of carbon black particles, synthesis of silica from TEOS, and bonding between adsorbed PVP and synthesized silica. And, if the above steps are carried out at a temperature exceeding 50 ℃, there is a problem that the reaction occurs rapidly in the silica production step by the sol-gel reaction of TEOS is not generated on the carbon black surface.

The stirring of the step of adsorbing the PVP on the surface of the carbon black particles and the stirring of the step of combining the synthesized silica with the PVP on the surface of the carbon black particles are preferably performed for 12 to 48 hours, and are performed for 24 to 36 hours. It is more desirable to be. If the agitation is performed for less than 12 hours, there is a problem that physical adsorption of PVP and chemical bonding of silica are not sufficiently performed, and there is no advantage even more than 48 hours.

Through the above steps, it is possible to prepare a carbon black / silica composite in which silica particles of several nm to several ten nm are bonded to the carbon black particle surface.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples and the like do not limit the scope of the present invention, and those skilled in the art to which the present invention pertains variously within the equivalent range of the technical concept of the present invention and the claims to be described below. Of course, modifications and variations are possible.

Example 1 Preparation of Carbon Black / Silica Composite (1-1)

0.3 g of PVP (M _w = 40,000, KANTO, Japan) and 400 g of distilled water were added to the reactor, and ultrasonic waves were added until the PVP was completely dissolved. Thereafter, 1 g of carbon black (N762, Degussa, Germany) was added to distilled water in which PVP was dissolved, and the mixture was stirred at room temperature for 24 hours to physically adsorb PVP onto the surface of carbon black.

The reaction mixture was filtered and redispersed in 100 ml of ethanol, and 4.4 ml of ammonia water (Duksan, Korea) and 4 ml of TEOS (Samchun, Korea) were added and stirred at room temperature for 24 hours to obtain a carbon black / silica complex. . The obtained complex was confirmed through a transmission electron microscope. The content of each component for the preparation of the composite is shown in Table 1.

Example 2 Preparation of Carbon Black / Silica Composite (1-2)

A carbon black / silica composite was obtained in the same manner as in Example 1 except that 1.0 g of PVP was added. The content of each component for the preparation of the composite is shown in Table 1.

Example 3 Preparation of Carbon Black / Silica Composite (1-3)

A carbon black / silica composite was obtained in the same manner as in Example 1, except that 1.5 g of PVP was added. The obtained complex was confirmed through a transmission electron microscope, and the results are shown in FIG. 3. According to Figure 3, it can be seen that on the surface of the carbon black particles, silica that looks like black dots having an average size of 2 nm is synthesized. The content of each component for the preparation of the composite is shown in Table 1.

Carbon black
(g) Distilled water
(g) PVP
(g) ethanol
(ml) ammonia
(ml) TEOS
(ml) Example 1 One 400 0.3 100 4.4 4 Example 2 One 400 1.0 100 4.4 4 Example 3 One 400 1.5 100 4.4 4

Example 4 Preparation of Carbon Black / Silica Composite (2-1)

1.5 g of PVP and 400 g of distilled water were added to the reactor, and ultrasonic waves were applied until the PVP was completely dissolved. 1 g of carbon black was added to distilled water in which PVP was dissolved, and stirred at room temperature for 24 hours to physically adsorb PVP on the surface of carbon black.

The reaction mixture was filtered and redispersed in 100 ml of ethanol. Then, 4.4 ml of ammonia water and 3 ml of TEOS were added thereto and stirred at room temperature for 24 hours to obtain a carbon black / silica composite. The content of each component for the preparation of the composite is shown in Table 2.

Example 5 Preparation of Carbon Black / Silica Composite (2-2)

A carbon black / silica composite was obtained in the same manner as in Example 4 except that 4 ml of TEOS was added. The obtained complex was confirmed through a transmission electron microscope, and the results are shown in FIG. 3. According to Figure 3, it can be seen that on the surface of the carbon black particles, silica that looks like black dots having an average size of 2 nm is synthesized. The content of each component for the preparation of the composite is shown in Table 2.

Example 6 Preparation of Carbon Black / Silica Composite (2-3)

A carbon black / silica composite was obtained in the same manner as in Example 4 except that 5 ml of TEOS was added. The obtained composite was confirmed through a transmission electron microscope, the results are shown in FIG. According to FIG. 4, it can be seen that silica particles having an average size of 20 nm cover the entire carbon black surface. The content of each component for the preparation of the composite is shown in Table 2.

Carbon black
(g) Distilled water
(g) PVP
(g) ethanol
(ml) ammonia
(ml) TEOS
(ml) Example 4 One 400 1.5 100 4.4 3 Example 5 One 400 1.5 100 4.4 4 Example 6 One 400 1.5 100 4.4 5

Comparative Example 1

0.1 g of PVP and 400 g of distilled water are added to the reactor and ultrasonic waves are applied until the PVP is completely dissolved. 1 g of carbon black was added to distilled water in which PVP was dissolved, and stirred at room temperature for 24 hours to physically adsorb PVP on the surface of carbon black.

The reaction mixture was filtered and redispersed in 100 ml of ethanol, and 4.4 ml of ammonia water and 5 ml of TEOS were added and stirred at room temperature for 24 hours to obtain a carbon black / silica composite. The obtained composite was confirmed through a transmission electron microscope and the results are shown in FIG. According to FIG. 2, it can be seen that the amount of PVP adsorbed on the surface of the carbon black is small, and thus the synthesized silica does not adhere to the carbon black particles and is separately synthesized on the medium. The size of the synthesized silica was about 100 nm larger than that of carbon black. The content of each component for the preparation of the composite is shown in Table 3.

Comparative Example 2

2.0 g of PVP and 400 g of distilled water were added to the reactor, and ultrasonic waves were applied until the PVP was completely dissolved. 1 g of carbon black was added to distilled water in which PVP was dissolved, and stirred at room temperature for 24 hours to physically adsorb PVP on the surface of carbon black.

The reactants were not filtered, and the subsequent silica synthesis did not proceed.

Carbon black particles adsorbed excessively by PVP were confirmed by transmission electron microscope, and the results are shown in FIG. 5. According to FIG. 5, it can be seen that PVP is thickly adsorbed around the round carbon black particles. The content of each component for the preparation of the composite is shown in Table 3.

Carbon black
(g) Distilled water
(g) PVP
(g) ethanol
(ml) ammonia
(ml) TEOS
(ml) Comparative Example 1 One 400 0.1 100 4.4 5 Comparative Example 2 One 400 2.0 - - -

Comparative Example 3

1.5 g of PVP and 400 g of distilled water were added to the reactor, and ultrasonic waves were applied until the PVP was completely dissolved. 1 g of carbon black was added to distilled water in which PVP was dissolved, and stirred at room temperature for 24 hours to physically adsorb PVP on the surface of carbon black.

The reaction mixture was filtered and redispersed in 100 ml of ethanol, 4.4 ml of ammonia water was added, and the mixture was stirred at room temperature for 24 hours without adding TEOS.

Particles after the reaction were confirmed through a transmission electron microscope, which is shown in FIG. 6. According to FIG. 6, since TEOS, which is a precursor of silica, was not added, it can be seen that only carbon black is present after the reaction without the synthesized silica. The content of each component for the preparation of the composite is shown in Table 4.

Carbon black
(g) Distilled water
(g) PVP
(g) ethanol
(ml) ammonia
(ml) TEOS
(ml) Comparative Example 3 One 400 1.5 100 4.4 0

1 is a transmission electron micrograph of the carbon black particles used in the present invention.

FIG. 2 is a transmission electron micrograph of carbon black and silica particles in a state in which the synthesized silica is not bonded to the carbon black due to the small amount of PVP adsorbed on the carbon black of Comparative Example 1 prepared by the sol-gel method according to the present invention. .

3 is a transmission electron micrograph of the carbon black / silica composite of Example 3 and Example 5 prepared by the sol-gel method according to the present invention.

Figure 4 is a transmission electron micrograph of the carbon black / silica composite of Example 6 prepared by the sol-gel method according to the present invention.

5 is a transmission electron microscope photograph of carbon black in which PVP is excessively adsorbed in Comparative Example 2. FIG.

6 is a transmission electron micrograph of the carbon black particles of Comparative Example 3 reacted in the absence of TEOS.

Claims (3)

Dispersing polyvinylpyrrolondone (PVP) in a range of 0.075 to 0.375 parts by weight with respect to 100 parts by weight of distilled water, and introducing carbon black to adsorb PVP on the surface of the carbon black; Dispersing the carbon black particles adsorbed by the PVP in a mixed solvent of ethanol and ammonia water in an ammonia water of 4 to 5 volume ratio relative to 100 ethanol volume ratio; Synthesizing TEOS in a range of 3 to 7 by volume with respect to 100 volumes by weight of ethanol in the mixed solvent to silica by a sol-gel method; And Bonding the synthesized silica to the surface of carbon black adsorbed with PVP; Method of producing a carbon black / silica composite comprising a. The method of claim 1, wherein each of the steps is performed for 12 to 48 hours at a reaction temperature of 20 to 50 ℃. delete

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