JPH08157643A - Water-repellent/oil-repellent porous silica particle and water-repellent/oil-repellent coating film - Google Patents

Abstract

PURPOSE: To obtain water-repellent/oil-repellent fine powder excellent in water repellency and oil repellency, physicochemical durability,weatherability, lubricity, dispersibility, nontackiness, etc. CONSTITUTION: The water-repellent/oil-repellent porous silica particles is obtained by chemically binding a perfluorohydrocarbon group-contg. silane derivative onto the surface of spherical porous silica particles each 100-1500m<2> /g in specific surface area, 0.6-3.0ml/g in pore volume, 4-300nm in average pore diameter and 0.01-350μm in particle diameter.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to water- and oil-repellent porous silica particles and a water- and oil-repellent coating film.

[0002]

2. Description of the Related Art Conventionally, a water-repellent paint has a molecular weight of 50.
It is known that low molecular weight tetrafluoroethylene resin fine particles of 0 to 20,000 and fluorinated at the terminal are mixed and dispersed in a resin as a water repellent powder (Japanese Patent Laid-Open No. 6-122).
No. 838, Japanese Utility Model Publication No. 2-78148, etc.). Further, it is known that the surface of a polymer composition exhibits water repellency due to a structure in which inorganic fine particles whose surface is coated with a fluorocarbon-based chemical adsorption film are dispersed in a polymer matrix resin (JP-A-6- See Japanese Patent Publication No. 200074). Alternatively, water- and oil-repellent fluorinated graphite ultrafine particles obtained by reacting acetylene black with fluorine gas are known (see JP-A-63-210009).

[0003]

However, the conventional water-repellent powder and water-repellent fine particles or the coating film containing them have the water- and oil-repellent performance and the durability performance such as abrasion resistance and chemical resistance at the same time. There was nothing to be satisfied. An object of the present invention is to provide water and oil repellent particles which are excellent in water and oil repellency and have high durability such as abrasion resistance and chemical resistance.

[0004]

The present invention has a specific surface area of 10
0 to 1500 m ² / g, pore volume 0.6 to 3.0 ml /
g, a water- and oil-repellent porous silica particle in which a perfluorohydrocarbon group-containing silane derivative is chemically bonded to the surface of the porous silica particle having an average pore diameter of 4 to 300 nm.

The perfluorohydrocarbon group-containing silane derivative is a silanol group (≡Si-) on the surface of porous silica particles.
OH). For example, an alkoxy group directly bonded to silicon (≡Si—O
R), a chloride group (≡Si—Cl), an isocyanate group (≡Si—NCO), an amino group (≡Si—NH ₂ ), and the like have a reactive group such as a condensation reaction with a silanol group and become porous. A perfluorohydrocarbon group can be provided on the surface of the crystalline silica. That is, the perfluorohydrocarbon group-containing silane derivative in the present invention is preferably composed of at least one compound selected from chlorosilane, alkoxysilane, isocyanate silane, and aminosilane containing a perfluorohydrocarbon group. Examples of various silane derivatives containing a perfluorohydrocarbon group include the following.

[0006]

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(Wherein R _f is a perfluoroalkyl group having 4 to 16 carbon atoms, m is an integer of 1 or more, and n is an integer of 4 to 16), or a silane derivative containing a perfluorohydrocarbon group, or a perfluorocarbon A hydrogen derivative is a silane derivative having an ether bond. Furthermore, a condensate obtained by hydrolyzing one or more of these silane derivatives, or a mixture of two or more of these can also be used.

Isocyanate silanes such as R _f (CH ₂ ) ₂ Si (NCO) ₃ are particularly preferable as the perfluorohydrocarbon group-containing silane derivative. This is because alkoxysilane requires heating to dehydrate-condense with the OH groups on the surface of silica particles to form a strong siloxane bond, whereas isocyanatesilane can form a siloxane bond at room temperature. In addition, chlorosilane easily reacts with OH groups on the surface of silica particles, but the reaction rate is fast, so it reacts rapidly even with moisture in the air, so care must be taken when handling it. On the other hand, isocyanate silane has a moderate reaction rate, and the reaction by-products are ammonia and carbon dioxide gas, which are easy to handle and suitable for industrial use.

The porous silica particles have a specific surface area of 100 to 1
It is necessary to be 500 m ² / g. Specific surface area 10
When it is less than 0 m ² / g, the amount of the perfluorohydrocarbon group-containing silane derivative reacting on the surface of the silica particles is small and sufficient water / oil repellency cannot be obtained, which is not suitable. When the specific surface area exceeds 1500 m ² / g, the water / oil repellency is no longer improved, and the perfluorohydrocarbon group-containing silane derivative reacts more than necessary on the particle surface, which is industrially wasteful. Specific surface area of porous silica particles is 3
It is more preferable if it is from 00 to 900 m ² / g.

The pore volume of the porous silica particles is from 0.6 to
It is required to be 3.0 ml / g. Pore volume 0.
If the amount is less than 6 ml / g, the volume of the perfluorohydrocarbon group-containing silane derivative that can be supported is insufficient, so that durable water / oil repellency cannot be obtained, which is unsuitable. If the pore volume exceeds 3.0 ml / g, the durable water repellent performance will no longer be improved, and rather the particles will become bulky and the strength of the particles will decrease, making them unsuitable for purposes such as hardness modification. It is more preferable that the pore volume of the porous silica particles is 0.9 to 2.1 ml / g.

The average pore radius of the porous silica particles is 4 to 3
It needs to be 00 nm. When the average pore diameter is less than 4 nm, the perfluorohydrocarbon group-containing silane derivative has a monomolecular film thickness of about 2 nm, and a uniform coating reaction cannot be obtained as a monomolecular film on the silica particle surface, which is not suitable.
If the average pore radius exceeds 300 nm, the water-repellent and oil-repellent performance obtained as a deposited film will not be improved, which is unsuitable. The average pore radius of the porous silica particles is 6 to 200n
It is more preferable that it is m.

The porous silica particles have a particle size of 0.01 to 35.
When it is 0 μm and is spherical or finely pulverized, it can be used widely as a filler for improving the physical properties of rubbers and resins from applications in the field of coatings where transparency and coloring are required, or due to the texture and function of fillers for cosmetics. It is preferable because it can respond. If the average particle size is less than 0.01 μm, the water / oil repellency is not sufficiently obtained, and the porous silica particles are apt to aggregate, and it is difficult to obtain uniformly dispersed water / oil repellent porous silica particles as a filler. Therefore, it is not preferable. If the average particle size exceeds 350 μm, the film-forming property of the composition containing silica particles as a filler becomes poor, which is not preferable. The average particle size of the porous silica particles is 0.05 to 3
It is more preferable if it is 0 μm. When the silica particles are spherical, the fluidity is improved, which is particularly preferable.

The porous silica particles have a SiO ₂ purity of 9
It is preferably 9.9% by weight or more. It is preferable that the silica particles are porous silica particles that do not substantially contain an alkali component in the components thereof or on the surface thereof. If the purity of SiO ₂ is less than 99.9% by weight, the silica surface and the siloxane bond of the perfluorohydrocarbon group-containing silane derivative are likely to be hydrolyzed due to the elution of the alkali content, so that the highly durable water and oil repellency cannot be maintained. Not preferable. Si
It is more preferable that the O ₂ purity is 99.99% by weight or more.

The water- and oil-repellent porous silica particles of the present invention are not particularly limited and can be used for various purposes. For example, when it is added as a filler to a paint, physical properties such as durability, water / oil repellency, hardness, surface slipperiness, and moisture resistance of the coating film can be improved. When blended with rubber, synthetic resin, fats and oils, etc., it can improve lubricity, fluidity, etc., or has a function as a thickener, a thixotropic agent, and an antiblocking agent. It can also be used as a surface modifier such as a water / oil repellent or a matting agent on the surface of a film or synthetic leather. Information industry paper (thermal recording paper, inkjet paper, etc.), general coated paper, papermaking filler such as strike-through prevention agent, cosmetics filler (lotion, putty, cream, lipstick, body powder), vehicle wax additive It can also be used as a water-permeable porous insulating material for building materials. Also in other fields, it can be used as a fluidity improver, an anti-icing agent, a snow accumulation inhibitor, an anti-caking agent, an anti-adhesion agent, a lubricity improving agent, a moistureproofing agent and the like.

[0015]

In the present invention, the water-repellent and oil-repellent porous silica particles have a structure chemically bonded to the perfluorohydrocarbon group-containing silane derivative. Therefore, the surface of the porous silica particles is entirely covered with the perfluorohydrocarbon group, and water and oil repellency is exhibited. In addition, it disperses well in paints, resins, organic solvents, etc., especially when added to fluorine-based resins, films, rubbers, and solvents, which were difficult to add in the past, and evenly disperses it to improve water / oil repellency and hardness. Can contribute to improvement. The binding between the perfluorohydrocarbon group-containing silane derivative and the porous silica particle is a siloxane bond due to the silanol group on the surface of the silica particle and the hydrolyzable reactive group of the perfluorohydrocarbon group-containing silane derivative being chemically bonded. Therefore, high durability of water and oil repellency is exhibited.

Since the porous silica particles have the above-mentioned pore characteristics, the surface area of the silica particles is large, the adsorption density of the adsorbed perfluorohydrocarbon group-containing silane derivative is very high, and Due to the volume effect in the adsorption process of the perfluorohydrocarbon group-containing silane derivative in step 1, the fluorine-containing concentration can be extremely increased, and the water- and oil-repellent performance excellent in durability can be realized.

[0017]

EXAMPLES The present invention will be specifically described below based on examples, but the following examples do not limit the scope of the present invention. In the examples, the evaluation method is as follows.

Water repellency measurement: Evaluation was made using the contact angle of a water drop. Kyowa Interface Science Co., Ltd. CA-A type measuring instrument was used to measure the contact angle, and the water droplet diameter was 1.5 mm to avoid the influence of weight.
It was measured at φ.

Abrasion resistance measurement: Load of 1.0k using flannel cloth
The sample surface was rubbed under the condition of g / cm ^{2, and} the abrasion resistance was evaluated from the change in water repellency depending on the contact angle.

Measurement of chemical resistance: After being immersed in a 0.1 N NaOH solution for 24 hours at room temperature, washed with water and dried, the chemical resistance was evaluated from the change in water repellency depending on the contact angle.

Light resistance measurement: The coating film was irradiated with light having a wavelength of 295 to 450 nm (irradiation intensity 90 mW / cm ² ) for 1000 hours (manufactured by Dainippon Plastics Co., Ltd., trade name super accelerated weather resistance tester Eye Super UV Tester SUV). After using -F11), the light resistance was evaluated from the change in water repellency depending on the contact angle.

Pencil hardness measurement: In accordance with JIS K5651, a pencil scratch tester (JIS K5401) was used to make a judgment using a pencil (Mitsubishi Pencil Co., Ltd., trade name Uni).

Adhesion measurement: The coating film was cross-cut in accordance with JIS K5400, and then the coating film was peeled off with cellophane tape (cellophane tape # 405 manufactured by Nichiban Co., Ltd., trade name). The adhesiveness was evaluated based on the number X of goggles, which remained without peeling after the test, out of 100 goggles.

[Synthesis Example 1] R _f CH = CH ₂ (where
R _f : C _n F _{2n + 1} , n: 6,8,10,12, mixture: average value 9.0) 49.6 g (0.1 mol), HSiCl
₃ 15.9 g (0.12 mol), H ₂ PtCl ₆・ 6H
0.2 g of 50% isopropanol solution of ₂ O in an internal volume of 1
The mixture was placed in a 00 ml glass pressure-resistant ampoule and reacted at 85 ° C. for 20 hours while shaking. After completion of the reaction, a reaction product was obtained by distillation under reduced pressure. When the reaction product is analyzed by gas chromatography, R _f (CH ₂ ) ₂ SiCl
₃ (bp 85 ° C. to 100 ° C./3 to 5 mmHg) was confirmed. The conversion rate to it was 95%.

[Synthesis Example 2] 50.3 g (0.08 mol) of R _f (CH ₂ ) ₂ SiCl ₃ which is the reaction product of Synthesis Example 1 is mixed with 15 g of methanol, and dry nitrogen is bubbled through the mixture. The reaction was carried out while removing HCl. The end point of this reaction was confirmed by quantitatively measuring generated HCl. After completion of the reaction, excess methanol was distilled off to obtain a reaction product. It was confirmed by gas chromatography that the reaction product was R _f (CH ₂ ) ₂ Si (OCH ₃ ) ₃ . The conversion rate to that was 100%.

[Synthesis Example 3] The reaction product R _f of Synthesis Example 1
A solution prepared by dissolving 50.3 g (0.08 mol) of (CH ₂ ) ₂ SiCl ₃ in 50 ml of benzene was added with 0.31 g (0.0016 mol) of triethylamine / methanesulfonate.
And 5.2 g (0.28 mol) of sodium cyanate
It was added dropwise with stirring to a liquid dissolved and suspended in 0 ml of benzene. After completion of dropping, the mixture was reacted under reflux at 80 ° C. for 2 hours, then cooled and solids were separated by filtration, benzene was distilled off from the filtrate, and the residue was distilled to obtain a reaction product. The reaction product did not contain chlorine, and when analyzed by its infrared absorption spectrum, it was confirmed to be R _f (CH ₂ ) ₂ Si (NCO) ₃ because it showed strong absorption of νNCO at 2290 cm ⁻¹ . The conversion rate to that was 80%.

[Synthesis Example 4] 190 g of 30% by weight sulfuric acid was added to 460 g of No. 3 water glass having a SiO ₂ concentration of 23% by weight.
g was reacted to form a silicic acid sol having a pH of 2. Next, when this sol was cooled to -1 ° C, 90 g of sodium sulfate was deposited and filtered off. Next, in a container with a capacity of 2 liters equipped with a stirrer and a gas blowing nozzle,
Nonionic surfactant sorbitan monooleate 2
Add 1.7 liters of toluene added 500 ppm,
While stirring at a stirring intensity of 10,000 rpm, the silicic acid sol was dropped to form an emulsion. The particle size of the sol obtained here was about 18 μm, which was close to a true sphere. Next, ammonia gas was blown through the gas blowing nozzle at a rate of 2 liters / minute for 5 minutes, and stirring was continued for another 60 minutes. During this time, the liquid temperature was maintained at 30 ° C. Next, the slurry was taken out of the container, the solid content was filtered off, the toluene attached to the solid content was treated with steam to be removed, and dried to obtain porous silica particles.

The SiO ₂ purity of the powder was 99.95% by weight, and as a result of observation with a scanning electron microscope, it was found that the average particle diameter was 5 μm and the particle diameter in the sol state was retained. . Specific surface area by BET method is 300m ² /
g, the pore volume by the nitrogen adsorption method was 1.0 ml / g, and the average pore diameter was 15 nm. Further, by the same method, the pH of the silicic acid sol, the particle size of the sol in the emulsion, and the like were changed, and porous silica powder having various physical properties described below was also synthesized.

[Synthesis Example 5] Si (OC ₂ H ₅ ) ₄ 10
7.14 g (0.5 mol), ethanol 820.97
g, 0.2 N hydrochloric acid 71.89 g (H ₂ O 3.9 mol) was placed in a flask equipped with a stirrer and reacted at room temperature for 24 hours, and then 3.0 wt% in consideration of SiO _2. A sol solution of tetraethoxysilane hydrolyzed condensate was obtained.

Example 1 Reaction product R _f of Synthesis Example 1
A solution was prepared by diluting 10 g of (CH ₂ ) ₂ SiCl ₃ with an ethyl acetate solvent to 100 g. Next, 1.0 g of the porous silica particles of Synthesis Example 4 (see Table 1 for physical properties) was added to this solution with stirring, ultrasonic waves were applied for 3 hours, and the solution was left standing for 1 hour. Thereafter, the solid content was separated by filtration, washed with hexane, filtered, and dried at 80 ° C. The contact angle of water and hexadecane was measured on the surface of the coating layer obtained by coating the water- and oil-repellent porous silica particles thus obtained on a glass substrate. The results are shown in Table 1.

Example 2 Reaction product R _f of Synthesis Example 2
10 g of (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , 168 g of isopropyl alcohol, and 2.6 g of a 0.1N acetic acid solution were placed in a flask equipped with a stirrer and reacted at room temperature for 48 hours, and then, Synthesis Example 4 ( For the physical properties, refer to Table 1) and add 1.0 g of porous silica particles, and sonicate for 3 hours.
Stirred for hours. Then, the solid content was separated by filtration, washed with ethanol, filtered, and dried and cured at 160 ° C. The surface of the coating layer obtained by spreading the water- and oil-repellent porous silica particles thus obtained on a glass substrate, water,
The contact angle with hexadecane was measured. The results are shown in Table 1.

Example 3 Reaction product R _f of Synthesis Example 3
A solution was prepared by diluting 30 g of (CH ₂ ) ₂ Si (NCO) ₃ with a dichloropentafluoropropane solvent to 300 g. Next, 3.0 g of the porous silica particles of Synthesis Example 4 (see Table 1 for physical properties) was added to this solution with stirring,
Ultrasonic waves were applied for 3 hours and left for another 12 hours. Then, the solid content was separated by filtration, washed with dichloropentafluoropropane, filtered, and dried at 80 ° C. The contact angle of water and hexadecane was measured on the surface of the coating layer obtained by coating the water-repellent and oil-repellent porous silica particles thus obtained on a glass substrate. The results are shown in Table 1.

[Examples 4 to 7] A water- and oil-repellent porous silica was obtained in the same manner as in Example 3 except that the porous silica particles were changed to those having the physical properties shown in Table 1. The contact angle of water and hexadecane was measured on the surface of the coating layer obtained by coating the water- and oil-repellent porous silica particles thus obtained on a glass substrate. The results are shown in Table 1.

[0034]

[Table 1]

[Example 8] For comparison, the same procedure as in Example 3 was repeated except that the porous silica particles were replaced with non-porous silica particles having an average particle size of 5 µm and a specific surface area of 7 m ² / g. Oily silica particles were obtained. Similarly, when it was spread on the glass surface and the contact angles with water and hexadecane were measured, they were 117 ° and 70 °, respectively. Example 1
The contact angle was smaller than that of No. 8.

[Example 9] For comparison, the average particle size is 7 μm.
m and a melting point of 332 ° C., low-molecular-weight PTFE powder was spread on a glass substrate, and the contact angles with water and hexadecane were measured to be 115 ° and 61 °, respectively. The contact angle was small as compared with Examples 1 to 8.

Example 10 To 16.7 g of the solution of the tetraethoxysilane hydrolyzed condensate of Synthesis Example 5, 2 g of the water- and oil-repellent porous silica particles of Example 6 was added and coated on a glass substrate. It was heated at 200 ° C. for 30 minutes to form a water and oil repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[Example 11] In Example 10, the amount of the solution of the tetraethoxysilane hydrolysis condensate was 33.4.
A water- and oil-repellent coating film was formed by the same experiment except that the amount was changed to g. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[Example 12] In Example 10, the amount of the solution of the tetraethoxysilane hydrolysis-condensation product was changed to 66.8.
A water- and oil-repellent coating film was formed by the same experiment except that the amount was changed to g. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

Example 13 The molecular weight was 3000 and-(C
11 of PTFE oligomer having F ₂ CF ₂ ) _n -structure
2 g of the water-repellent and oil-repellent porous silica particles of Example 6 was added to 18.2 g of a fluorinated hydrocarbon solvent-based dispersion liquid (manufactured by Asahi Glass Co., Ltd., trade name AG-Lub G) at a weight percentage, and the mixture was placed on a glass substrate. It was applied and heated at 200 ° C. for 30 minutes to form a water and oil repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[Example 14] 1.6 wt% perfluorocycloalkane-based solution of amorphous fluororesin (Asahi Glass Co., Ltd., trade name CYTOP CTL-102M) 1
To 25 g, 2 g of water- and oil-repellent porous silica particles of Example 6
Was added and coated on a glass substrate and heated at 200 ° C. for 30 minutes to form a water / oil repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[Example 15] 100 g of a fluororesin coating (Lumiflon LF-100, manufactured by Asahi Glass Co., Ltd.)
Was added to 5 g of the water- and oil-repellent porous silica particles of Example 6 and coated on a glass substrate, and heated at 80 ° C. for 30 minutes to form a water- and oil-repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[Example 16] Silicone type hard coat paint (manufactured by Shin-Etsu Chemical Co., Ltd., trade name X-12-23)
To 100 g of 21A), 8 g of the water- and oil-repellent porous silica particles of Example 6 was added and coated on a glass substrate, and heated at 120 ° C. for 90 minutes to form a water- and oil-repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[Example 17] To 30 g of synthetic fluoro oil (manufactured by Asahi Glass Co., Ltd., product name Freonlube FL-900),
1 g of the water- and oil-repellent porous silica particles of Example 6 was added and coated on a glass substrate to form a water- and oil-repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

Example 18 Tetrafluoroethylene / ethylene copolymer (Asahi Glass Co., Ltd., trade name AFLON CO
P) 1000 g and 10 g of the water- and oil-repellent porous silica particles of Example 6 were added, and the mixture was heated and kneaded to form a film, which was then heat-bonded to a degreased cold-rolled steel sheet for water- and oil-repellency. A coating film was formed. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[Example 19] For comparison, the tetraethoxysilane hydrolysis-condensation solution of Synthesis Example 5 was coated on a glass substrate without adding any filler, and heated at 200 ° C for 30 minutes for coating. A film was formed. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

Example 20 For comparison, 66.8 g of a solution of the tetraethoxysilane hydrolyzed condensate of Synthesis Example 5
2 g of the water- and oil-repellent silica particles of Example 8 having an average particle diameter of 1 μm were added to and coated on a glass substrate, and heated at 200 ° C. for 30 minutes to form a water- and oil-repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water. The contact angle of hexadecane on the surface of the coating film was less than 20 °.

[Example 21] For comparison, 66.8 g of a solution of the tetraethoxysilane hydrolyzed condensate of Synthesis Example 5 was compared.
2 g of the PTFE powder of Example 9 was added thereto and well dispersed, and then coated on a glass substrate and heated at 200 ° C. for 30 minutes to form a water / oil repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[Example 22] For comparison, the PTFE oligomer dispersion used in Example 13 was coated on a glass substrate without adding any filler and heated at 200 ° C for 30 minutes to form a coating film. did. Table 2 shows the results of evaluation of the coating film by the contact angle with water. The contact angle of hexadecane on the surface of the coating film was 62 °.

[Example 23] For comparison, the solution of the amorphous fluororesin used in Example 14 was applied onto a glass substrate and heated at 200 ° C for 30 minutes to form a water / oil repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water. The contact angle of hexadecane on the surface of the coating film was 60 °.

[Example 24] For comparison, the fluororesin paint used in Example 15 was applied on a glass substrate and heated to 80 ° C.
And heated for 30 minutes to form a water and oil repellent coating film. Table 2 shows the results of evaluation of the coating film by the contact angle with water.

[0052]

[Table 2]

In Table 2, it can be seen that Examples 10 to 18 have large contact angles and good durability as compared with Examples 19 to 24 given as comparative examples.

[0054]

The water- and oil-repellent porous silica particles of the present invention are water- and oil-repellent, waterproof, anticorrosive, snow-resistant, weather resistant,
Excellent lubricity. By incorporating the water- and oil-repellent porous silica particles of the present invention as a filler, it becomes possible to form a coating film having good water- and oil-repellency. Since the water- and oil-repellent porous silica particles of the present invention have strong water- and oil-repellency, the effect can be exhibited even in a small amount. For example, semiconductor encapsulant additives,
Even when it is used as a filler for various resins, paints, adhesives, and a filler for cosmetics, it is inexpensive because it can exhibit high-performance effects with a small amount, and can be widely applied as other surface treatment materials.

When porous silica particles having a SiO ₂ purity of 99.9% by weight or more and having substantially no alkali content in the components of the silica particles or on the surface thereof are used as the porous silica particles, Na, Since it does not contain impurities such as Fe and Al and has a high degree of purity, it can be applied not only as a material for the electronics industry, but also when used in the chemical industry, the steel industry, the non-ferrous metal industry, the glass industry, and optical applications. The effect that water-repellent performance has high long-term durability is obtained.
Further, since the water- and oil-repellent porous silica particles of the present invention have high electric resistance and high dielectric properties, they can be applied to electric insulating materials and materials to which chargeability is desired.

The water- and oil-repellent porous silica particles of the present invention are excellent in productivity, can be easily mass-produced by a relatively simple process and apparatus, and have an extremely high industrial value.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Rare Yoneda 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Asahi Glass Co., Ltd. Central Research Laboratory

Claims (4)

[Claims] 1. A specific surface area of 100 to 1500 m ² / g, a pore volume of 0.6 to 3.0 ml / g, and an average pore diameter of 4 to 300 n.
Water- and oil-repellent porous silica particles in which a perfluorohydrocarbon group-containing silane derivative is chemically bonded to the surface of the porous silica particles of m. 2. A porous silica particle having a particle size of 0.01 to 350.
The water- and oil-repellent porous silica particle according to claim 1, which is a spherical spherical silica particle having a diameter of μm. 3. Porous silica particles having a SiO ₂ purity of 99.
The water- and oil-repellent porous silica particle according to claim 1 or 2, which is 9% by weight or more, and is a porous silica particle which does not substantially contain an alkali component in a component of the silica particle or on a surface thereof. 4. A water and oil repellent coating film comprising the water and oil repellent porous silica particles according to any one of claims 1 to 3 as a filler.