KR102521764B1 - Silica masterbatch preparation method and silica masterbatch prepared therefrom - Google Patents

Abstract

The silica masterbatch manufacturing method of the present invention and the silica masterbatch prepared therefrom can be mixed without loss or scattering in the mixing process, so that scattered (blown) silica can be reduced, and silica particles are easily dispersed, so that the working environment and It has the effect of improving product quality stability.
In addition, the method for preparing the silica masterbatch of the present invention and the silica masterbatch prepared therefrom can be continuously produced, thereby reducing process costs and providing excellent process efficiency.

Description

Silica masterbatch manufacturing method and silica masterbatch prepared therefrom {SILICA MASTERBATCH PREPARATION METHOD AND SILICA MASTERBATCH PREPARED THEREFROM}

The present invention relates to a method for preparing a silica masterbatch and a silica masterbatch prepared therefrom. When the silica masterbatch is used as a blending material of a polymer, scattering (blown) silica can be reduced, and quantitative blending and continuous production It relates to a processable silica masterbatch manufacturing method and a silica masterbatch prepared therefrom.

In general, silica is used as a reinforcing filler such as carbon black in the rubber industry, and various types of silica have been developed along with the development of the rubber industry. In particular, in order to improve the poor working environment of the rubber industry and to manage and improve quality, masterbatch used by pre-dispersing in rubber has been widely spread, thereby dramatically improving the working environment of the rubber industry. However, silica has not yet been commercialized as a masterbatch due to the bulk structure and surface chemical properties of silica. In addition, when a high-concentration silica masterbatch is prepared as in the conventional form, the spacing between the silica particles is narrowed, so that the white color in the bulk form becomes almost translucent, and the silica masterbatch prepared in this way is not well dispersed when used as a polymer compounding agent There are downsides to not having

Accordingly, rubber compound manufacturers that use silica in the form of powder or granules rather than master batches have environmental problems due to dust generation when silica is applied to products due to scattering of silica, product quality stability, and worker's disease. causing very serious problems such as In order to solve the problem of silica scattering, silica manufacturers and various research institutes are also making efforts, and it is urgent to develop a silica masterbatch that can improve this.

Accordingly, the inventors of the present invention tried to solve the above-mentioned problems by providing a method for manufacturing a dry silica masterbatch through "Silica masterbatch and its manufacturing method (10-2003-0031237)". However, in this case, the manufacturing process is long, so the production cost is high, and there is a problem in that some undispersed grains appear when the rubber compounding agent is used. Accordingly, the inventors of the present invention tried to solve these problems by providing a "latex-bound low-flying silica composition and a method for producing the same (10-2006-0022690)". However, in this case, while dispersion is easy during mixing, a continuous manufacturing process is not possible, so a batch process must be additionally performed, resulting in a decrease in process efficiency. There was a limit where mixing was impossible.

Korean Patent Publication 10-2003-0031237 Korean Patent Publication 10-2006-0022690

The problem to be solved by the present invention is to provide a method for preparing a silica masterbatch capable of reducing scattered (blown) silica and at the same time quantitatively blending and continuous manufacturing process, and a silica masterbatch prepared therefrom.

In order to solve the above problems, the present invention (1) obtaining a silica master batch composition by mixing the silica mixture solution and the binder solution in a mixing unit; (2) transferring the silica masterbatch composition to a settling tank through a transfer unit; (3) forming aggregates by injecting a coagulant into the transfer part while transferring the silica masterbatch composition to the precipitation bath; and (4) obtaining a silica masterbatch from the aggregate, wherein the binder solution is a latex-containing binder solution or a polymer emulsion.

According to a preferred embodiment of the present invention, a silica mixture may be prepared by mixing 200 to 400 parts by weight of water with respect to 100 parts by weight of silica before step (1).

According to a preferred embodiment of the present invention, in step (1), 10 to 70 parts by weight of the binder solution based on the solid content of the binder solution may be mixed with 100 parts by weight of silica in the silica mixture.

According to a preferred embodiment of the present invention, the latex may be at least one selected from the group consisting of natural rubber (NR) latex, styrene-butadiene rubber (SBR) latex, and nitrile-based rubber (NBR) latex.

According to a preferred embodiment of the present invention, the polymer emulsion may be at least one selected from the group consisting of polyurethane (PU) emulsion, ethylene vinyl acetate (EVA) emulsion and polyvinyl alcohol (PVA) emulsion.

According to a preferred embodiment of the present invention, the coagulant may be at least one selected from the group consisting of magnesium sulfate, aluminum sulfate, citric acid (C ₆ H ₈ O ₇ ), and lactic acid (C ₃ H ₆ O ₃ ).

According to a preferred embodiment of the present invention, the silica contained in the silica mixture may be coated with oil or wax in an amount of 0.1 to 5% by weight.

According to a preferred embodiment of the present invention, the silica mixture may further include a surfactant (emulsifier), a starch oligomer, an alcohol having a melting point of 30° C. or less, and an acrylic thickener alone or in combination.

According to a preferred embodiment of the present invention, in the step (4), the silica masterbatch may be obtained by drying the agglomerates on a belt having a sieve structure or performing drying after centrifugation.

In addition, the present invention provides a silica masterbatch prepared from any one of the above-described silica masterbatch manufacturing methods.

The silica masterbatch manufacturing method of the present invention and the silica masterbatch prepared therefrom can be mixed without loss or scattering in the mixing process, so that scattered (blown) silica can be reduced, and silica particles are easily dispersed, so that the working environment and It has the effect of improving product quality stability.

In addition, the method for preparing the silica masterbatch of the present invention and the silica masterbatch prepared therefrom can be continuously produced, thereby reducing process costs and providing excellent process efficiency.

1 is a process flow diagram according to one preferred embodiment of the present invention.
2 is an external image of a conventional silica masterbatch.
3 is an external image of a silica masterbatch according to a preferred embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, an embodiment of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention.

First, the terms used in the specification of the present invention will be briefly described.

The term 'any one or more' means to include both 'any one selected from the corresponding group' and 'a mixture of two or more selected from the corresponding group'.

As described above, in the past, when applying silica to a product, there were difficulties such as environmental problems due to dust generation due to scattering of silica, product quality stability, and disease occurrence of workers. Accordingly, the inventors of the present invention provide "silica masterbatch and manufacturing method thereof (10-2003-0031237)" and "latex-bound low-flying silica composition and manufacturing method thereof (10-2006-0022690)" to reduce silica scattering. However, some undispersed grains appear when using a rubber compounding agent, and a continuous manufacturing process is impossible, so a batch process must be additionally performed, resulting in a decrease in process efficiency. In some cases, the silica is rapidly adsorbed to form a film, so it was difficult to manufacture a uniform masterbatch, and thereafter, there was a limitation in that a lot of energy was consumed to remove moisture.

Accordingly, the present invention provides (1) obtaining a silica masterbatch composition by mixing the silica mixture and the binder solution in a mixing unit; (2) transferring the silica masterbatch composition to a settling tank through a transfer unit; (3) forming aggregates by injecting a coagulant into the transfer part while transferring the silica masterbatch composition to the precipitation bath; And (4) obtaining a silica masterbatch from the aggregate; the binder solution is a latex-containing binder solution or a polymer emulsion to provide a method for preparing a silica masterbatch to seek a solution to the above-mentioned limitations.

Accordingly, the present invention can be blended without loss or scattering in the mixing process to reduce scattered (blown and scattered) silica, and has the effect of improving the working environment and product quality stability because silica particles are easily dispersed. In addition, since continuous manufacturing is possible, process cost reduction is possible, and process efficiency is excellent.

1 is a process flow diagram according to one preferred embodiment of the present invention. Referring to FIG. 1, the present invention is a step (S1) of obtaining a silica masterbatch composition by mixing a silica mixture and a binder solution in a mixing unit, transferring the silica masterbatch composition to a settling tank through a transfer unit (S2), In the course of transferring the silica masterbatch composition to the precipitation tank, a coagulant is introduced into the transfer unit to form aggregates (S3) and a silica masterbatch is obtained from the aggregates (S4).

First, (1) a step (S1) of obtaining a silica masterbatch composition by mixing a silica mixture and a binder solution in a mixing section will be described.

A silica masterbatch composition can be prepared by mixing and uniformly stirring the silica mixture solution and the binder solution through the step (1).

The silica mixed solution is a mixed solution containing silica, and may include silica and water according to a preferred embodiment of the present invention. In some cases, various additives may be further included.

In addition, the contents of silica and water included in the silica mixture may be in an appropriate range according to the oil absorption of silica, and preferably, the content of water included in the silica mixture may be greater than the oil absorption of silica. More preferably, the silica mixture may include 200 to 400 parts by weight of water based on 100 parts by weight of silica. More preferably, the silica mixture may include 250 to 350 parts by weight of water based on 100 parts by weight of silica.

When the contents of silica and water included in the silica mixture are within the above range, the silica mixture may have fluidity, thereby facilitating the manufacturing process.

If the silica mixture contains water less than the above range, fluidity is low, and it is difficult to uniformly perform agitation and transfer through a pipe may be difficult.

According to a preferred embodiment of the present invention, the silica contained in the silica mixture may be coated with oil or wax in an amount of 0.1 to 5% by weight. More preferably, it may be coated with 0.2 to 1% by weight, and more preferably, it may be coated with 0.3 to 0.5% by weight.

By coating and treating the surface of the silica as described above, the present invention has the effect of improving the dispersibility when the masterbatch is used as a compounding agent, and the moisture of the latex-containing binder solution or polymer emulsion used as the binder solution is rapidly absorbed into the silica. It has the effect of preventing this. In addition, when drying the silica masterbatch, the drying time can be shortened due to the water repellent effect, thereby improving the drying efficiency.

Meanwhile, in some cases, the silica mixture may further include various additives commonly used in the related art.

Preferably, the silica mixture may further include a surfactant (emulsifier), a starch oligomer, an alcohol having a melting point of 30° C. or less, and an acrylic thickener alone or in combination. In addition, the additive may be included in an amount of 2.5 to 15 parts by weight based on 100 parts by weight of the silica mixture.

The surfactant can perform a uniform coating of silica and can perform the function of reinforcing the silica. As surfactants, anionic dioctyl sodium sulfosuccinate, benzophenone-9, cationic laurelkonium chloride, stearalkonium chloride, Nonionic Cocamide MEA, modified cocamide DEA, and the like can be used.

A thickener is a material that increases the viscosity of a liquid, and those commonly used in the art may be used.

The binder solution is an intermediate medium for uniformly dispersing silica to prepare a silica masterbatch, and in the present invention, a latex-containing binder solution or a polymer emulsion is used as the binder solution.

The latex-containing binder solution refers to a solution containing latex, and the content range of the latex can be appropriately selected to the extent that the silica can be evenly dispersed and the silica can be bound to prepare a silica masterbatch.

Preferably, the latex-containing binder solution may include 40 to 60% by weight of latex, more preferably 45 to 55% by weight of latex. At this time, the meaning of including the latex in weight% of the above range means that the moisture is removed and completely dried latex solids are included in the weight% of the above range.

In this case, process efficiency can be improved by reducing the separation time with water in the centrifugal separation process described later, and when the silica masterbatch is applied to the polymer, scattering of silica is significantly reduced.

If the latex-containing binder solution contains latex less than the above range, scattering of silica may occur when the silica masterbatch is used as a compounding agent. In addition, when the mile latex-containing binder solution contains latex in excess of the above range, it has the effect of reducing silica scattering, but the silica concentration is low and the amount of silica master batch is relatively increased to design the formulation, resulting in high mixing costs. this can happen

In addition, the latex may be a kind commonly used in the art, but preferably selected from the group consisting of natural rubber (NR) latex, styrene-butadiene rubber (SBR) latex and nitrile rubber (NBR) latex can be one or more of the

A polymer emulsion includes a polymer material and is composed of at least two immiscible liquid phases, one of which is a thermodynamically unstable system dispersed in another liquid phase. The content range of the polymer emulsion may be appropriately selected to the extent that the silica masterbatch can be prepared by binding the silica in the same solid content range as latex while uniformly dispersing the silica.

According to a preferred embodiment of the present invention, the polymer emulsion may be at least one selected from the group consisting of polyurethane (PU) emulsion, ethylene vinyl acetate (EVA) emulsion and polyvinyl alcohol (PVA) emulsion. At this time, it is preferable that the polymer emulsion is a water dispersion type and excludes nonionic properties.

If a nonionic emulsion is used as a binder, it is difficult to bind silica by breaking the emulsion, so a net or centrifugal separator cannot be used to separate water, and a lot of cost may be incurred in removing water by drying.

In addition, according to a preferred embodiment of the present invention, in step (1), 10 to 70 parts by weight of the binder solution based on the solid content of the binder solution may be mixed with 100 parts by weight of silica in the silica mixture. More preferably, it can be mixed in 11 to 50 parts by weight. In this case, since silica can be evenly dispersed, quantitative mixing is possible, and thus, physical properties can be improved overall.

On the other hand, it is preferable to prepare a silica mixture solution by mixing 200 to 400 parts by weight of water with respect to 100 parts by weight of silica before step (1).

In this way, when the silica mixture solution is first prepared before mixing the silica mixture solution and the binder solution, the binding (aggregation) process described later can be effectively performed.

If silica, water, and a binder solution are simultaneously added and mixed without pre-preparation of the silica mixture, water is rapidly adsorbed to form a silica film (film), which may cause a problem of inhibiting aggregation of the binder solution. Therefore, in the present invention, a silica masterbatch composition must be prepared by preparing a silica mixture solution in advance and then mixing it with a binder solution so that a continuous manufacturing process is possible, resulting in excellent process efficiency, easy particle dispersion during stirring, and quantitative mixing. The effect of improving product quality can be achieved.

Meanwhile, as described above, the content range in which the binder solution is mixed may be determined according to the concentration of the binder solution, that is, the solid content. Therefore, the content of the binder solution mixed with the silica mixture may be determined according to the concentration of the above-described latex-containing binder solution. For example, when a latex-containing binder solution having a solid content of 50% by weight with respect to 100 parts by weight of silica in the silica mixture is mixed, 50 parts by weight of latex solids may be mixed with respect to 100 parts by weight of silica. In addition, when a latex-containing binder solution having a solid content of 70% by weight with respect to 100 parts by weight of silica in the silica mixture is mixed, 70 parts by weight of latex solids may be mixed with respect to 100 parts by weight of silica.

Mixing of the silica mixture solution and the binder solution in step (1) may be performed in a mixing unit. At this time, the mixing unit may be a tank or a solution bath.

In addition, the mixing may be performed through a stirrer in the mixing unit while maintaining appropriate fluidity.

At this time, a high-speed stirrer may be used as the stirrer, and the stirring speed of the high-speed stirrer is preferably 200 to 500 rpm and the stirring time is 60 to 300 seconds. If the stirring speed or stirring time exceeds the above range, the silica tends to lean toward the wall of the stirrer, making uniform binding difficult and there is a risk that the bound silica may rather fall off, and the stirring speed or stirring time is less than the above range There is a concern that the part where silica can come into contact with latex or emulsion, which is a binder, will be reduced.

Next, (2) the step (S2) of transferring the silica masterbatch composition to the sedimentation tank through the transfer unit will be described.

Through the step (2), the silica masterbatch composition may be transferred to a settling tank where precipitation and separation are performed.

Next, (3) the step (S3) of forming agglomerates by introducing a coagulant into the conveying unit while transferring the silica masterbatch composition to the precipitation bath will be described.

Through the step (3), the silica masterbatch composition is agglomerated by the agglomerates introduced into the transfer unit to form agglomerates. In this way, in the case of forming agglomerates in the conveying unit, it is possible to prevent the problem of agglomerates sticking to the stirrer when the silica and latex mixture is added from the tank tank, and the silica is evenly bound to provide uniform quality of high content. Eggplant has the effect of providing a silica masterbatch.

If the coagulant is added in the mixing section consisting of a tank or solution tank instead of the conveying section to perform agglomeration, difficulties such as sticking of the coagulant to the stirrer in the mixing section and clumping occur, making it impossible to manufacture a silica masterbatch of uniform quality. There may be problems that cannot be solved, and some of the silica may not be bound by the binder, so that a high content of aggregate may not be formed, and thus it may be difficult to prepare a silica masterbatch in a quantitative amount.

That is, in the method for preparing the silica masterbatch of the present invention, a coagulant must be added to the transfer unit during transfer of the silica masterbatch composition to the precipitation tank to form agglomerates to prevent clogging of the transfer piping, and silica is uniformly distributed throughout the composition. It is possible to achieve the effect of providing a silica masterbatch having a high content and uniform quality by being bound.

The coagulant is an agent that causes aggregation of the silica masterbatch composition including silica, a binder, and other additives, and various agents that cause aggregation by adjusting pH commonly in the art may be used. Preferably, the coagulant may be at least one selected from the group consisting of magnesium sulfate, aluminum sulfate, citric acid (C ₆ H ₈ O ₇ ), and lactic acid (C ₃ H ₆ O ₃ ).

In this case, the aggregation of the silica masterbatch composition can be performed at a high speed, so that agglomerates can be formed in the transfer pipe, so that water can be separated from the silica and rubber latex or polymer emulsion mixture to quickly form a silica masterbatch, , it is possible to provide a silica masterbatch having a high content and uniform quality in which the silica is evenly bound.

Next, step (4) of obtaining a silica masterbatch from the aggregate (S4) will be described.

The step (4) is a silica masterbatch manufacturing method, characterized in that to obtain a silica masterbatch by drying the aggregate after centrifugation.

Furthermore, the present invention provides a silica masterbatch prepared from any one of the above-described silica masterbatch manufacturing methods.

Through this, the present invention has the effect of improving the working environment and product quality stability by reducing scattered (scattered) silica. In addition, a continuous manufacturing process is possible, resulting in excellent process efficiency, easy particle dispersion during stirring, and a binder function, enabling quantitative mixing.

Hereinafter, the present invention will be described in more detail based on examples.

Example 1

A silica mixture solution was prepared by mixing and stirring 60 parts by weight of silica and 180 parts by weight of water in a tank to have fluidity. Thereafter, 80 parts by weight of the silica mixture and a NBR latex binder solution having a solid content of 50% by weight were added to the primary tank and stirred for 4 minutes to prepare a mixed composition. While the mixed composition was being transferred through a transfer pipe, a coagulant was added to form agglomerates. Thereafter, the silica is precipitated separately from the binder solution and separated from water. After obtaining a wet silica masterbatch separated from water, primary water removal was performed through a centrifugal separator. Thereafter, tunnel-type oven drying was performed to obtain a silica masterbatch.

Example 2

A silica mixture was prepared by mixing and stirring 70 parts by weight of silica and 210 parts by weight of water in a tank to have fluidity. Thereafter, 60 parts by weight of the silica mixture and a 50% by weight NR latex binder solution were added to the first tank, stirred for 2 minutes, transferred to the second tank, and further stirred for 2 minutes to prepare a mixed composition. While the mixed composition was being transferred through a transfer pipe, a coagulant was added to form agglomerates. Thereafter, the silica is precipitated separately from the binder solution and separated from water. After obtaining a wet silica masterbatch separated from water, primary water removal was performed through a centrifugal separator. Thereafter, tunnel-type oven drying was performed to obtain a silica masterbatch.

Example 3

A silica mixture was prepared by mixing and stirring 80 parts by weight of silica and 240 parts by weight of water in a tank to have fluidity. Thereafter, 40 parts by weight of the silica mixture and 50% by weight of the SBR latex binder solution were added to the first tank, stirred for 2 minutes, transferred to the second tank, and further stirred for 2 minutes to prepare a mixed composition. While the mixed composition was being transferred through a transfer pipe, a coagulant was added to form agglomerates. Thereafter, the silica is precipitated separately from the binder solution and separated from water. After obtaining a wet silica masterbatch separated from water, primary water removal was performed through a centrifugal separator. Thereafter, tunnel-type oven drying was performed to obtain a silica masterbatch.

Example 4

65 parts by weight of silica and 195 parts by weight of water were mixed and stirred in a tank to have fluidity to prepare a silica mixture. Thereafter, 100 parts by weight of the silica mixture and 35% by weight of the PU emulsion binder solution were added to the primary tank and stirred for 4 minutes to prepare a mixed composition. While the mixed composition was being transferred through a transfer pipe, a coagulant was added to form agglomerates. Thereafter, the silica is precipitated separately from the binder solution and separated from water. After obtaining a wet silica masterbatch separated from water, primary water removal was performed through a centrifugal separator. Thereafter, tunnel-type oven drying was performed to obtain a silica masterbatch.

comparative example

A silica mixture was prepared by mixing and stirring 70 parts by weight of silica and 210 parts by weight of water in a tank to have fluidity. Thereafter, the same procedure as in Example 1 was performed except that a coagulant was added to the silica mixture in a tank to form aggregates.

Experimental Example 1. Observation of appearance of silica masterbatch

The appearance of the silica masterbatch prepared in Example 1 and Comparative Example was observed.

matter Example 1 Example 2 Example 3 Example 4 Comparative Example 1 silica
mixture silica 60 70 80 65 70 PEG 200 - - - 3 water (H2O) 180 210 240 195 210 bookbinder NBR latex 80 - - - - NR latex - 60 - - 60 SBR Latex - - 40 - - PU emulsion - - - 100 - coagulant aluminum sulfate
5% 50 50 50 50 50 location of agglutination transfer pipe transfer pipe transfer pipe transfer pipe in the tank
bulk agglomeration appearance observation almost no powder Powder Excess Occurrence NBR Latex: Kumho Petrochemical
NR latex: Malaysian natural latex
SBR Latex: Kumho Petrochemical
PU emulsion: Shinchang Industrial Co., Ltd. polyurethane emulsion, WPU-10, 35%
Silica: Rhodia Zeosil 175

Referring to Table 1, it can be seen that in the case of the silica masterbatch prepared through the method for preparing the silica masterbatch of the present invention, aggregation of silica and latex occurs smoothly, and powder is hardly generated. On the other hand, it can be seen that when bulk aggregation occurs in a tank rather than in a transfer pipe as in Comparative Example 1, an excessive amount of powder is generated, resulting in an excessive amount of silica scattering.

In this regard, FIG. 2 is an external image of a conventional silica masterbatch prepared according to a comparative example, and FIG. 3 is an external image of a silica masterbatch prepared according to Example 1 of the present invention. Specifically, FIGS. 2 (a) and 3 (a) are external images of the silica masterbatch observed on a lab scale basis, and FIGS. 2 (b), 2 (c), 3 (b) and 3 ( c) is an external image of the silica masterbatch observed on a pilot scale basis. Referring to Figures 2 and 3, it can be seen that in the case of the comparative example, there is a problem in that excessive powder is generated because the silica is not sufficiently aggregated. In addition, in the case of Example 1 of the present invention, it can be seen that the silica is sufficiently aggregated and there is almost no powder. Through this, it can be seen that the present invention can significantly reduce silica scattering.

Claims (10)

(1) obtaining a silica masterbatch composition by mixing the silica mixture and the binder solution in a mixing unit;
(2) transferring the silica masterbatch composition to a settling tank through a transfer unit;
(3) forming agglomerates by injecting a coagulant into the transfer part while transferring the silica masterbatch composition to the precipitation bath; and
(4) obtaining a silica masterbatch from the aggregate;
Before step (1), 200 to 400 parts by weight of water is mixed with respect to 100 parts by weight of silica to prepare a silica mixture,
In step (1), 11 to 50 parts by weight of a binder solution based on the solid content of the binder solution is mixed with respect to 100 parts by weight of silica in the silica mixture,
The silica contained in the silica mixture is coated with 0.3 to 0.5% by weight of oil or wax,
The binder solution is a silica masterbatch manufacturing method of a latex-containing binder solution or a polymer emulsion.
delete delete According to claim 1,
The silica masterbatch manufacturing method, characterized in that the latex is at least one selected from the group consisting of natural rubber (NR) latex, styrene-butadiene rubber (SBR) latex and nitrile rubber (NBR) latex.
According to claim 1,
The polymer emulsion is a silica masterbatch manufacturing method, characterized in that at least one selected from the group consisting of polyurethane (PU) emulsion, ethylene vinyl acetate (EVA) emulsion and polyvinyl alcohol (PVA) emulsion.
According to claim 1,
The coagulant is a masterbatch manufacturing method, characterized in that at least one selected from the group consisting of magnesium sulfate, aluminum sulfate, citric acid (C ₆ H ₈ O ₇ ) and lactic acid (C ₃ H ₆ O ₃ ).
delete According to claim 1,
The silica mixture solution further comprises a surfactant (emulsifier), a starch oligomer, an alcohol having a melting point of 30 ° C or less, and an acrylic thickener alone or in combination with additives.
According to claim 1,
In the step (4), the silica masterbatch is prepared by drying the aggregate on a belt having a sieve structure or performing drying after centrifugation to obtain a silica masterbatch.
delete

Images