Method for preparing hydrophobic silica and hydrophobic silica prepared thereby

Abstract

The present invention relates to a method for preparing hydrophobic silica and hydrophobic silica prepared thereby and, more specifically, to a method for preparing high-quality hydrophobic silica and hydrophobic silica prepared thereby, whereby, by inducing a hydrophobization reaction of silica under a condition in which almost no moisture is present, the generation of corrosive gas while preparing hydrophobic silica can be suppressed, and thus corrosion of an apparatus for preparing hydrophobic silica can be prevented, such that the problem of deterioration in the quality of prepared hydrophobic silica due to such corrosion of an apparatus can be solved.

Description

Method for manufacturing hydrophobic silica and hydrophobic silica manufactured thereby

[0001] The present invention relates to a method for manufacturing hydrophobic silica and hydrophobic silica produced by the same, and more specifically, to a method for manufacturing hydrophobic silica by inducing a hydrophobic reaction of silica under conditions with almost no moisture to suppress the generation of corrosive gases, thereby preventing corrosion of the hydrophobic silica manufacturing apparatus, and thus resolving the problem of quality degradation of the hydrophobic silica produced due to such apparatus corrosion, and to hydrophobic silica produced by the same.

[0002]

[0003] When manufacturing hydrophobic silica (e.g., precipitated silica, fumed silica, etc.) using conventional silanes (dimethyldichlorosilane, methyltrichlorosilane, chlorotrimethylsilane, ethyltrichlorosilane, diethyldichlorosilane, chlorotriethylsilane, phenyltrichlorosilane, diphenyldichlorosilane, methylphenyldichlorosilane, etc.), the process is mainly carried out in a batch reactor made of metal. In order to promote the reaction for manufacturing the hydrophobic silica, a method has generally been used in which steam is introduced to accelerate the decomposition of the silanes and facilitate the reaction with the silica surface.

[0004] During this process, the decomposition of silanes generates a large amount of chlorine (Cl2), which reacts with moisture inside the device to produce hydrochloric acid (HCl). This hydrochloric acid not only causes corrosion to the reactors in the manufacturing equipment but also creates black dust due to the resulting corrosion. The main component of this black dust is Fe3O4, which, when mixed into the manufactured hydrophobic silica, causes a fatal degradation in quality and, in the worst-case scenario, renders the product impossible to sell.

[0005] To address the aforementioned problems, the introduction of post-treatment equipment utilizing magnetic materials to remove black dust has been considered; however, there are limitations as it is extremely difficult to completely remove it from among nanoparticles such as silica. In practice, the quality level of hydrophobic silica treated with silanes is primarily determined by the incorporation of black dust; since the final products, such as silicone or sealants, are transparent or white, black dust constitutes a critical quality issue.

[0006] In addition, hydrochloric acid generated during the manufacture of hydrophobic silica in a moist environment becomes significantly difficult to remove once it is sorbed between the silica particles. This can lower the pH of the silica product, leading to off-spec results. Furthermore, if production workers come into contact with silica products sorbed with hydrochloric acid, it can cause skin diseases and potentially lead to fatal problems upon respiration.

[0007] Therefore, it is necessary to develop a method for manufacturing high-quality hydrophobic silica that resolves the aforementioned problems and limitations, minimizes the generation of black dust and the resulting hydrochloric acid, and can safely extend the lifespan of the manufacturing equipment.

[0008]

[0009] The objective of the present invention is to provide a method for producing high-quality hydrophobic silica by using a dry method that does not use moisture such as steam, thereby minimizing the generation of black dust and the generation of hydrochloric acid, which is the cause thereof, and to provide the hydrophobic silica produced thereby.

[0010] In addition, the objective of the present invention is to provide a method for manufacturing hydrophobic silica that can resolve the problem of reducing the lifespan of a manufacturing apparatus due to moisture such as steam and the resulting hydrochloric acid, black dust, etc., and to provide hydrophobic silica manufactured thereby.

[0011] The objectives of the present invention are not limited to those mentioned above, and other objectives and advantages of the present invention not mentioned may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0012]

[0013] To achieve the above objective, according to one aspect of the present invention, (S1) a step of introducing hydrophilic silica into a metal reactor and stirring;

[0014] (S2) A step of injecting an inert gas into the reactor to form an inert atmosphere inside the reactor;

[0015] (S3) A step of raising the temperature inside the reactor to 300~400℃;

[0016] (S4) A step of introducing an organic silane into the reactor;

[0017] (S5) A step of sealing the reactor to form high-pressure conditions, and then obtaining hydrophobic silica by hydrophobization reaction of hydrophilic silica and organic silane; comprising,

[0018] The above-mentioned hydrophobic silica may provide a method for producing hydrophobic silica having a carbon content of 0.80 to 3.0 wt%, a metal impurity content of less than 1,000 ppb, and a methanol wettability of 40 ml or more.

[0019] The hydrophilic silica of (S1) above may include silica powder or silica spherical particles having a water content of 7 weight% or less and a pH of 7 or less.

[0020] The organic silane of (S4) above may be an organic silane containing a chloro group (-Cl).

[0021] The above-mentioned organic silane containing a chloro group may include one or more of dimethyldichlorosilane, methyltrichlorosilane, chlorotrimethylsilane, ethyltrichlorosilane, diethyldichlorosilane, chlorotriethylsilane, phenyltrichlorosilane, diphenyldichlorosilane, and methylphenyldichlorosilane.

[0022] The above (S1) to (S5) may be performed using a dry method that does not supply steam.

[0023] The high pressure of the above (S5) is 2 x 10 5 ~ 5 X 10 5 It may satisfy the range of Pa.

[0024] The hydrophobic silica obtained in (S5) above may have a water content of 0.5 weight% or less and a pH of 4 or higher.

[0025] The hydrophobic silica obtained in (S5) above may not contain black dust containing Fe3O4.

[0026] According to another embodiment of the present invention, hydrophobic silica produced by the method for producing hydrophobic silica according to one embodiment of the present invention can be provided, wherein the hydrophobic silica has a carbon content of 0.80 to 3.0 weight%, a metal impurity content of less than 1,000 ppb, and a methanol wettability of 40 ml or more.

[0027] The above hydrophobic silica may not contain black dust containing Fe3O4.

[0028] The above hydrophobic silica may have a water content of 0.5 weight% or less and a pH of 4 or higher.

[0029]

[0030] The method for manufacturing hydrophobic silica according to the present invention utilizes a dry method that does not use moisture, such as steam, thereby minimizing the generation of hydrochloric acid and preventing the occurrence of black dust. Furthermore, this prevents corrosion of the reactor in the hydrophobic silica manufacturing apparatus, enables the production of high-quality hydrophobic silica free from black dust, and has the advantage of resolving safety issues caused by hydrochloric acid adsorption.

[0031] In addition to the effects described above, the effects of the present invention are described together with the details for implementing the invention below.

[0032]

[0033] In describing this specification, if it is determined that a detailed description of related prior art could unnecessarily obscure the gist of this specification, such detailed description is omitted.

[0034] Throughout this specification, unless specifically stated otherwise, each component may be singular or plural.

[0035] In interpreting the components in this specification, they are interpreted to include an error range even if there is no separate explicit description.

[0036] Where terms such as “comprising,” “containing,” “having,” “consisting of,” “arranging,” or “equipping” are used for a component in this specification, other parts may be added unless “only” is used. Where a component is expressed in the singular, it includes cases where it is included in the plural unless specifically stated otherwise.

[0037] Throughout this specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" or "C to D" means C or more and D or less unless specifically stated otherwise.

[0038] Unless otherwise specifically stated regarding units in this invention, they are interpreted as being based on “weight,” and for example, if only “%” is indicated in this specification, it is interpreted to mean “weight% (wt%).”

[0039] In interpreting the components in this specification, they are interpreted to include an error range even if there is no separate explicit description.

[0040]

[0041] The present invention will be described in more detail below.

[0042] A method for manufacturing hydrophobic silica according to one aspect of the present invention is,

[0043] (S1) A step of introducing hydrophilic silica into a metal reactor and stirring;

[0044] (S2) A step of injecting an inert gas into the reactor to form an inert atmosphere inside the reactor;

[0045] (S3) A step of raising the temperature inside the reactor to 300~400℃;

[0046] (S4) A step of introducing an organic silane into the reactor;

[0047] (S5) A step of sealing the reactor and then obtaining hydrophobic silica by a hydrophobic reaction of hydrophilic silica and an organic silane; may be included,

[0048] The hydrophobic silica obtained above may satisfy the following conditions: a carbon content of 0.80 to 3.0 wt%, a metal impurity of less than 1,000 ppb, and a methanol wettability of 40 ml or more.

[0049] In order to produce hydrophobic silica in the present invention, hydrophilic silica and an organic silane are used as reactants, and a hydrophobization reaction is carried out.

[0050] According to one example, the inert gas may include Ar gas, N2 gas, etc., but is not limited thereto.

[0051] According to one example, the hydrophilic silica may be one in which a hydrophilic group such as -OH (hydroxyl group) is bonded to the surface of the silica, or may be in a form in which silanol is present on the surface of the silica.

[0052] According to one example, the method for manufacturing hydrophobic silica of the present invention basically aims for conditions without moisture, but since the hydrophilic silica used as a raw material contains some moisture, it is preferable to use hydrophilic silica that satisfies a moisture content of 7 weight% or less and a pH of 7 or less.

[0053] According to one example, the hydrophilic silica has a silanol (Si-OH) density of 2.2 ea / nm 2 Silica powder or spherical silica particles of the above quality may be used. Since silanol provides reaction sites capable of hydrophobizing the surface of silica, a hydrophobization reaction is possible in the presence of silanol, so it is preferable that the density of silanol be within the above range.

[0054] According to one example, the specific surface area of ​​the hydrophilic silica is 50 to 800 m² based on BET analysis. 2 It may be used if it exhibits specific surface area characteristics of / g. If the specific surface area (BET) of hydrophilic silica is 50 m² 2 If it is less than / g, the number of silanols is low, so there may not be enough reaction sites available for hydrophobication, and 800 m 2 If the amount exceeds / g, aggregation of silica may occur due to the high specific surface area, and there may be a disadvantage of increased process costs as a large amount of treating agent (e.g., organosilane) must be added to exhibit hydrophobicity.

[0055] According to one example, the organic silane is not particularly limited as long as it is an organic silane containing a chloro group (-Cl). For example, the organic silane containing a chloro group may include one or more of dimethyldichlorosilane, methyltrichlorosilane, chlorotrimethylsilane, ethyltrichlorosilane, diethyldichlorosilane, chlorotriethylsilane, phenyltrichlorosilane, diphenyldichlorosilane, and methylphenyldichlorosilane, but is not limited thereto.

[0056] According to one example, the organic silane can be added in an amount of 5 to 20 weight percent relative to 100 weight percent of the hydrophilic silica. If the amount of organic silane is less than 5 weight percent, there may be a problem in that it does not meet the hydrophobicity intended in the present invention, and if it exceeds 20 weight percent, there may be a problem in that it has a higher degree of hydrophobicity than the hydrophobicity intended in the present invention, or a problem in that a larger amount of steam or inert gas is required in the reaction byproduct treatment process, and there may be a disadvantage in that the process economic efficiency is reduced as a result.

[0057] The hydrophobization reaction for producing hydrophobic silica occurs above the vaporization temperature of the organic silane. The organic silane is mixed with silica in a gaseous state and reacts with the surface silanol present on the surface of the silica. At this time, in the method for producing hydrophobic silica according to the present invention, if the organic silane and the silanol on the surface of the silica react in a dry manner, that is, in an atmosphere with almost no moisture, the amount of hydrochloric acid gas generated is significantly reduced, for example, to less than half, so the degree of corrosion of the reactor is greatly reduced or almost no corrosion occurs, and high-quality hydrophobic silica can be produced.

[0058] Meanwhile, conventional technology involves introducing silica into a metal batch reactor and raising the temperature to 250–350°C, which is above the vaporization temperature of the organic silane; once the reaction temperature is reached, the organic silane is introduced simultaneously with steam. At this time, the steam reacts with the organic silane to generate hydrochloric acid, a corrosive gas, while promoting the hydrophobization reaction. Additionally, since high-pressure steam increases the internal pressure of the reactor, the reactor vent is opened to reduce the internal pressure to approximately 1.01 x 10⁻⁶ 5 The hydrophobization reaction is carried out while maintaining the Pa level. Once the hydrophobization reaction is complete, an additional process must be performed to remove corrosive gases by flowing inert gas.

[0059] However, as described above, the method for manufacturing hydrophobic silica of the present invention uses a dry method that does not introduce steam, so it does not generate hydrochloric acid, which is a corrosive gas, while the hydrophobization reaction proceeds at a temperature of 300 to 400°C, which is slightly higher than conventional methods. By not introducing steam, the reaction of organic silanes with moisture other than surface silanol is suppressed, thereby minimizing the generation of corrosive gas during the reaction.

[0060] In addition, since high-pressure steam is not injected, the process can be carried out under high-pressure conditions with the reactor sealed; consequently, this offers the advantage of increased process efficiency and a further reduced possibility of impurity contamination. The aforementioned high pressure in a sealed state is, for example, 2 × 10⁻⁶ 5 ~ 5 × 10 5 It may satisfy the range of Pa, for example, 2.03 × 10 5 ~ 5.07 × 10 5It may satisfy the range of Pa. Furthermore, since the amount of corrosive hydrochloric acid gas generated is significantly reduced, there are advantages in the lifespan and maintenance of the device, and it is efficient because there is no need to necessarily perform a process of flowing inert gas to remove the corrosive gas. If a small amount of corrosive gas is generated or purging is required, it is desirable to perform a separate process of injecting inert gas, but there is an advantage that purging can be performed with a significantly smaller amount of inert gas compared to conventional technology.

[0061] Preferably, the hydrophobic silica produced above satisfies the following properties of the hydrophobic silica produced in the present invention (i) to (v), and furthermore, may not contain black dust containing Fe3O4.

[0062] (i) Methanol wettability of 40 ml or more, preferably 50 ml or more;

[0063] (ii) The carbon content is 0.80 to 3.0 weight%, preferably 0.90 to 2.0 weight%;

[0064] (iii) metal impurities are 1,000 ppb or less, preferably 200 ppb or less, more preferably 170 ppb or less;

[0065] (iv) moisture content of 0.5 weight% or less, preferably 0.3 weight% or less;

[0066] (v) pH is 4 or higher, preferably 5 or higher.

[0067] If the water content of the hydrophobic silica exceeds 0.5 weight%, it may cause problems such as reduced mechanical properties and water resistance of the final product when the hydrophobic silica is applied to the final product, such as silicone or adhesive.

[0068] If the pH of hydrophobic silica is less than 4, it is harmful to the skin and respiratory system of workers handling the hydrophobic silica and causes corrosion of the packaging bag, which may lead to problems due to damage to the packaging bag during the storage and distribution of the product.

[0069]

[0070] The present invention will be explained in more detail below through examples and experimental examples. However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0071]

[0072] Example 1

[0073] 100 g of hydrophilic silica was introduced into a SUS reactor and stirred. N2 gas was injected into the reactor as an inert gas to create an inert atmosphere inside the reactor. The temperature inside the reactor was raised to 350°C to set the hydrophobization reaction temperature to 350°C. The mixture was prepared by adding 11 wt% of dimethyldichlorosilane as a treatment agent relative to 100 wt% of the hydrophilic silica. During the hydrophobization reaction, there was no inflow or outflow of material except for the introduction of the organic silane into the reactor, and the reactor vent was closed to reduce the pressure to 2.6 x 10⁻⁶ 6 Hydrophobic silica was prepared by carrying out a hydrophobic reaction for 1 hour while maintaining Pa.

[0074]

[0075] Example 2

[0076] Hydrophobic silica was prepared in the same manner as in Example 1, except that the hydrophobization reaction temperature was 350 ℃.

[0077]

[0078] Comparative Example 1

[0079] Hydrophobic silica was prepared in the same manner as in Example 1, except that the hydrophobization reaction temperature was 250 ℃.

[0080]

[0081] Comparative Example 2

[0082] Hydrophobic silica was prepared in the same manner as in Example 1, except that the hydrophobization reaction temperature was 450 ℃.

[0083]

[0084] Comparative Example 3

[0085] Hydrophobic silica was prepared in the same manner as in Example 1, except that the hydrophobization reaction temperature was 550 ℃.

[0086]

[0087] Comparative Example 4

[0088] Hydrophobic silica was prepared using the same method as in Example 1, but under conditions present with moisture, by simultaneously introducing steam at a flow rate of 0.13 sccm with the organic silane during the hydrophobization reaction. The reaction temperature was 300°C, and the preparation was carried out by adding 11 wt% of dimethyldichlorosilane relative to 100 wt% of the hydrophilic silica. During the hydrophobization reaction, approximately 5 × 10 5 High-pressure steam of Pa is injected to open the reactor vent, and the pressure becomes 1.01 × 10 5 It was maintained at Pa.

[0089]

[0090] Table 1 below shows the methanol wettability, carbon content, and metal impurity content of the hydrophobic silica prepared in Examples 1 to 2 and Comparative Examples 1 to 4, respectively, measured using the method of Experimental Examples 1 to 3 below. The methanol wettability and carbon content can be used to confirm whether hydrophobization proceeded well.

[0091]

[0092] Experimental Example 1

[0093] Methanol wettability is a measurement used to analyze the hydrophobicity of hydrophobic silica, indicating the wettability of the hydrophobic silica to an organic solvent (methanol). Specifically, hydrophobic silica was added to distilled water, and methanol was added dropwise to settle the hydrophobic silica floating on the surface of the distilled water. Once all the hydrophobic silica had settled, the addition of methanol was stopped, and the volume added was measured.

[0094]

[0095] Experimental Example 2

[0096] The carbon content of hydrophobic silica was analyzed using Thermo Scientific’s Flash EA 1112 Series instrument. Specifically, the carbon was converted into carbon dioxide by burning hydrophobic silica in an oxygen atmosphere at 1000 °C, and the carbon content was analyzed by measuring the amount of carbon dioxide produced.

[0097]

[0098] Experimental Example 3

[0099] Metal impurities in hydrophobic silica were measured using Thermo Scientific's iCAP 7000 Series instrument. Specifically, hydrophobic silica was pretreated by mixing it with hydrofluoric acid and nitric acid and heating it; then, the pretreated samples were analyzed for metal impurities using ICP-OES, and the sum of the detected concentrations for seven elements—Fe, Cr, Al, Ti, Ni, Mo, and Mn—was presented.

[0100]

[0101] Reaction Temperature [°C] Methanol Wetness [ml] Carbon Content [wt.%] Metal Impurities [ppb] Example 1 300 42.5 0.9 1168 Example 2 350 50.2 1.1 3155 Comparative Example 1 250 32.8 0.7 8161 Comparative Example 2 450 53.7 1.2 3172 Comparative Example 3 550 54.1 1.2 5169 Comparative Example 4 300 48.1 1.1 28165

[0102]

[0103] As can be seen from Table 1, referring to Examples 1 and 2, methanol wettability and carbon content increased when the hydrophobization reaction temperature was increased. This means that the hydrophobization reaction can be promoted by increasing the reaction temperature with the reactor vent closed, even without introducing steam.

[0104] In addition, when comparing the carbon content of Example 2 and Comparative Example 4, it can be seen that hydrophobic silica having physical properties equivalent to those of hydrophobic silica produced by introducing steam can be produced without introducing steam.

[0105] On the other hand, when the reaction is carried out at a temperature lower than the reaction temperature range of 300 to 450°C as in Comparative Example 1, the reactivity is reduced, resulting in lower methanol wettability and lower carbon content. This means that the silica was not sufficiently hydrophobized.

[0106] In addition, comparing Comparative Examples 2 and 3, it can be seen that the methanol wettability and carbon content of hydrophobic silica increase up to a reaction temperature of 450°C, but do not increase further at 550°C. This is interpreted to mean that the hydrophobization reaction of silica is already saturated at 450°C.

[0107] In Comparative Example 4, a large amount of metal impurities was detected compared to Examples 1 and 2. This means that corrosive gases generated by the reaction of the organic silane with steam as well as the silanol on the silica surface due to the introduction of steam during the hydrophobization reaction promoted reactor corrosion. On the other hand, in Examples 1 and 2, since steam was not used during the hydrophobization reaction, the reaction of the organic silane with moisture other than the silica surface was suppressed, so it can be seen that reactor corrosion was improved compared to Comparative Example 4, with less corrosive gas generation.

[0108] This indicates that the manufacturing method of the present invention can produce hydrophobic silica with low metal impurities while exhibiting physical properties equivalent to those of hydrophobic silica produced by conventional technology. In the present invention, by producing hydrophobic silica at a reaction temperature 50 to 100°C higher and at a high pressure compared to conventional technology, the probability of reaction between the silica surface and the organic silane can be increased even without steam acting as a catalyst. Through this, the problem of reactor corrosion can be improved without degrading the physical properties of the hydrophobic silica, and high-quality hydrophobic silica can be produced.

[0109]

[0110] Although the present invention has been described in more detail with reference to the embodiments attached herein, the present specification is not necessarily limited to these embodiments and may be modified in various ways within the scope of the technical spirit of the present specification. Accordingly, the embodiments disclosed in the present specification are intended to explain, not limit, the technical spirit of the present specification, and the scope of the technical spirit of the present specification is not limited by these embodiments. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of protection of the present specification shall be interpreted by the claims, and all technical spirits within the equivalent scope shall be interpreted as being included within the scope of rights of the present specification.

Claims

1. (S1) A step of introducing hydrophilic silica into a metal reactor and stirring; (S2) A step of injecting an inert gas into the reactor to form an inert atmosphere inside the reactor; (S3) A step of raising the temperature inside the reactor to 300~400℃; (S4) A step of introducing an organic silane into the reactor; (S5) A step of sealing the reactor to form high-pressure conditions, and then obtaining hydrophobic silica by hydrophobization reaction of hydrophilic silica and organic silane; comprising, A method for producing hydrophobic silica, wherein the obtained hydrophobic silica has a carbon content of 0.80 to 3.0 wt%, metal impurities of less than 1,000 ppb, and methanol wettability of 40 ml or more.

2. In Paragraph 1, A method for producing hydrophobic silica, wherein the hydrophilic silica of (S1) comprises silica powder or silica spherical particles satisfying a water content of 7 weight% or less and a pH of 7 or less.

3. In Paragraph 1, A method for producing hydrophobic silica, wherein the organic silane of (S4) above is an organic silane containing a chloro group (-Cl).

4. In Paragraph 3, A method for producing hydrophobic silica, wherein the above-mentioned organic silane containing a chloro group comprises one or more of dimethyldichlorosilane, methyltrichlorosilane, chlorotrimethylsilane, ethyltrichlorosilane, diethyldichlorosilane, chlorotriethylsilane, phenyltrichlorosilane, diphenyldichlorosilane, and methylphenyldichlorosilane.

5. In Paragraph 1, A method for manufacturing hydrophobic silica, wherein the above (S1) to (S5) are performed by a dry method without supplying steam.

6. In Paragraph 1, The high pressure of the above (S5) is 2 × 10 5 ~ 5 × 10 5 A method for manufacturing hydrophobic silica satisfying the range of Pa.

7. In Paragraph 1, A method for producing hydrophobic silica, wherein the hydrophobic silica obtained in (S5) above has a water content of 0.5 wt% or less and a pH of 4 or higher.

8. In Paragraph 1, A method for producing hydrophobic silica that does not contain black dust containing Fe3O4, obtained in (S5) above.

9. Hydrophobic silica produced by a method for producing hydrophobic silica according to any one of claims 1 to 8, wherein Hydrophobic silica having a carbon content of 0.80 to 3.0 wt%, metal impurities of less than 1,000 ppb, and methanol wettability of 40 ml or more.

10. In Paragraph 9, The above hydrophobic silica is hydrophobic silica that does not contain black dust containing Fe3O4.

11. In Paragraph 9, The above hydrophobic silica is hydrophobic silica having a water content of 0.5 weight% or less and a pH of 4 or higher.