JP2008137859A - Ultrafine particle porous silica - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, regarding porous silica having pores with high regularity in a mesopore region, applications in various fields to a catalyst carrier, a separating agent or the like are examined, but, its cohesion is high, and its particle diameter is made large, thus the applications are limited, and to provide porous silica having pores with high regularity in a mesopore region and dispersed into a solvent to a submicron order. <P>SOLUTION: Disclosed is porous silica whose peak intensity is expressed by d<SB>100</SB>:d<SB>110</SB>:d<SB>200</SB>=100:5.0 to 20.0:5.0 to 10.0, and having the average particle diameter of 50 to 500 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to fine-particle-shaped porous silica having highly regular pores in a mesopore region and capable of being dispersed in a solvent with an average particle size on the order of submicrons.

  Porous silica with highly regular pores in the mesopore region has been studied for application in various fields such as catalyst carriers and separating agents. There was a problem that was limited. For example, in order to obtain a smooth and homogeneous film when used as a component of an ink absorbing layer of an ink jet recording paper or as an additive of a functional polymer film that imparts low dielectric properties or optical properties. However, it is required that the particle diameter is on the order of submicron while maintaining highly regular pores. Further, in the fields of catalyst carriers, separating agents, adsorbents, pharmaceutical carriers for pharmaceuticals, etc., they are used after being granulated or molded, or are used by being uniformly dispersed in a matrix. In order to improve the mechanical strength of the molded body and the dispersibility in the matrix, it is necessary to maintain the regularity of the mesopores and to make the porous silica fine particles.

  In view of the above problems, a method has been proposed in which fine porous silica is obtained by treating a mixed solution obtained by mixing porous silica and a cationic resin in an aqueous solvent with a high-pressure homogenizer. (For example, see Patent Document 1)

  However, the porous silica produced by such a method has a wide distribution of mesopores and has a problem in the uniformity of the pores, so that a catalyst carrier or a separation agent for a substance of a specific size can be used. It was difficult to apply for use. In addition, since a cationic resin is essential, its use is limited.

A wet pulverization method using an organic solvent as a dispersion medium has been proposed as a method of pulverizing while suppressing the collapse of the pore structure of porous silica. (For example, see Patent Document 2)
The above-mentioned method can only make fine particles up to about 10 μm, and if fine particles are made to submicron order, there is a problem that the pores collapse and the pore regularity is impaired.

JP 2002-356621 A (page 1 to page 8) JP 2000-44227 A (page 1 to page 3)

  An object of the present invention is to provide a porous silica in the form of fine particles having highly regular pores in a mesopore region and capable of being dispersed in a solvent with an average particle size on the order of submicrons.

That is, in the X-ray diffraction pattern of the present invention, the peak intensity is represented by a ratio of d ₁₀₀ : d ₁₁₀ : d ₂₀₀ = 100: 5.0 to 20.0: 5.0 to 15.0, and the average particle diameter Relates to a porous silica characterized by having a thickness of 50 to 500 nm. According to the present invention, porous silica that has high pore regularity and is dispersed in a solvent with an average particle size on the order of submicrons can be produced without performing a pulverization treatment after synthesis.

  According to the present invention, a porous material that exhibits a hexagonal structure (2d-hexagonal) in the mesopore region, has highly regular pores distributed in a narrow pore size range, and is dispersed in a solvent with an average particle size on the order of submicrons. Silica can be provided. When this porous silica is used as a component of an ink absorbing layer of an ink jet recording paper or used as a functional polymer film, a smooth and homogeneous film that has not been obtained conventionally can be obtained.

  The porous silica in the present invention has an average particle diameter of 50 to 500 nm, preferably 50 to 300 nm.

For the measurement of the average particle size, it is preferable to measure as a dispersion liquid that has been subjected to ultrasonic irradiation treatment in advance, and can be used for the measurement as follows, for example.
100 mg of a sample is added to 10 ml of ion-exchanged water and dispersed at 20 KHz, 200 W, 4.4 watt / cm ³ using an ultrasonic generator (Ultrasonic distributor / Tomy UD-200). The resulting dispersion is subjected to particle size distribution measurement.
The average particle diameter refers to a numerical value of the volume-based average diameter to be measured. The method for measuring the particle size distribution is not particularly limited, but it is preferably performed by a laser diffraction / scattering particle size distribution measuring apparatus.

The pore regularity of the porous silica in the present invention is confirmed by obtaining an X-ray diffraction pattern. If a large amount of moisture remains in the pores, the peak intensity of the d value will be lower than the actual value. Therefore, it is preferable to sufficiently dry the sample in advance for measuring the X-ray diffraction pattern. An example of the measurement method is shown below. The sample is heated at 80-120 ° C. for 1 hour or more and cooled in a desiccator. The cooled sample is placed on a plate for X-ray diffraction measurement and leveled so that it becomes a uniform plane. The X-ray diffraction pattern is measured using a fully automatic X-ray diffractometer (RINT ULTIMAII, manufactured by Rigaku Corporation). In X-ray diffraction pattern of the porous silica in this invention when _the ratio of the peak intensity of the _{d 100,} d _110, d _{200 is} that the peak intensity of the _{d 100} and _{100, d 100: d 110:} d 200 = 100: 5.0-20.0: 5.0-15.0 are preferable, and 100: 8.0-20.0: 7.0-15.0 are more preferable. Here, d ₁₀₀ , d ₁₁₀ , and d ₂₀₀ indicate the intervals of the (100) plane, the (110) plane, and the (200) plane, respectively, of the hexagonal structure of the X-ray diffraction pattern. As the regularity of the pores decreases, the peak intensities of d ₁₁₀ and d ₂₀₀ decrease. Especially for d _200, it is often the peak itself can not be sure will be unclear. Porous silica of the present invention, which can be confirmed as also clear peak to peak of d _200, the pore regularity is extremely high.

  The average pore diameter is not particularly limited, but is preferably 1 to 20 nm, more preferably 1 to 10 nm. If the average pore diameter is less than 1 nm, the pore volume is too small to provide low dielectric properties and optical properties. On the other hand, if the average pore diameter exceeds 20 nm, the physical strength of the pore walls is not sufficient to maintain the pore structure, which is not preferable. The average pore diameter can be determined by a known nitrogen adsorption measurement.

  The porous silica in the present invention includes those added with a metal species at the time of synthesis or after synthesis. It is known that when porous silica is exposed to hot water, steam, or an aqueous alkali metal salt solution, the pore walls of the silica dissolve with time, and the specific surface area and pore regularity of the pores are impaired. Yes. By adding a metal species at the time of synthesis or after synthesis, it is possible to obtain porous silica having excellent durability with little structural deterioration with respect to hot water, steam, or an aqueous alkali metal salt solution. As the metal species to be added, at least one is selected from the group consisting of Al, Zr, Ti, Fe, Ga, Sn, V, Cr, and Ru. The compound containing the metal species is preferably a compound that ionizes in water. For example, in the case of Al, sodium aluminate or aluminum nitrate, and in the case of Zr, zirconium hydrochloride, zirconyl nitrate, or the like can be used. The metal species may be added at any time during synthesis. Alternatively, it is possible to immerse the porous silica in an aqueous solution of the metal species after synthesis and obtain it through a drying step. The content of the metal species incorporated in the pore walls of the porous silica is preferably 4 wt% or less from the viewpoint of the pore regularity of the porous silica.

Although the manufacturing method of the porous silica of this invention is not specifically limited, It is preferable to carry out through the following 1st, 2nd, 3rd processes.
1st process: The process of disperse | distributing alkoxysilane to the cationic surfactant solution of pH1-pH3.
Second step: A step in which a complex of silica and a surfactant forms a gel by adding an alkali source to pH 8.5 to pH 9.5.
3rd process: The process of removing surfactant from the obtained composite_body | complex.

  In the first step, the alkoxysilane is hydrolyzed under mild acidic conditions of pH 1 to pH 3 in the presence of a cationic surfactant. The pH condition of the reaction in the first step is preferably pH 1 to pH 3 and more preferably pH 1.5 to pH 2.5 from the viewpoint of regularity of the pores. The acid used for adjusting the pH is not particularly limited, and can be widely used, such as mineral acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as acetic acid, but the pH can be adjusted with a smaller amount of acid. A mineral acid which is a strong acid is preferable from the viewpoint of carrying out.

  In the second step, silicate polycondensation proceeds under mild basic conditions of pH 8.5 to pH 9.5. The pH condition of the reaction in the second step is preferably pH 8.5 to 9.5, more preferably pH 9.0, from the viewpoint of regularity of the pores. The alkali source used for adjusting the pH is not particularly limited, and a wide range of alkali sources such as sodium hydroxide and potassium hydroxide can be used. However, porous silica having a finer average particle diameter is synthesized. From this viewpoint, ammonia is preferable. Ammonia refers to ammonia, urea, and the like. Urea has an amino group in the molecule and decomposes under acid to generate ammonia. In addition, from the viewpoint of obtaining more finely divided porous silica, water may be added before the adjustment of pH 8.5 to 9.5 in the second step. The water addition ratio is not particularly limited, but from the viewpoint of regularity of the pore structure, water addition of 0.5 to 5 times the weight of the reaction solution before addition is preferable.

  In the third step, the surfactant is removed from the resulting composite. Examples of the method for removing the surfactant in the third step include a method of baking at 400 ° C. to 600 ° C. and a method of extracting with an organic solvent. In the case of adopting a firing method as a method for removing the surfactant, it is necessary to concentrate and dry the complex-containing sol obtained in the second step. Concentration / drying methods include a method of concentrating and drying the complex-containing sol as it is, and a method of filtering the complex-containing sol and drying the concentrated complex. When the method of heating and concentrating and drying the composite-containing sol as it is, the heating temperature is preferably 50 ° C to 100 ° C, more preferably 60 ° C to 80 ° C, and more preferably 65 ° C to 75 ° C from the viewpoint of regularity of the pores. Further preferred. In the method of filtering the composite-containing sol and drying the concentrated composite, the drying temperature is not particularly limited. Further, the solid content after drying is preferably 80% to 100% in any case, more preferably 90% to 100%, and most preferably 95% to 100%.

  Cationic surfactants include primary amine salts, secondary amine salts, tertiary amine salts, quaternary ammonium salts, etc. From the viewpoint of pore regularity, quaternary ammonium salts are preferred. preferable.

  Quaternary ammonium salts include octyltrimethylammonium chloride, octyltrimethylammonium bromide, octyltrimethylammonium hydroxide, decyltrimethylammonium chloride, decyltrimethylammonium bromide, decyltrimethylammonium hydroxide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, Dodecyltrimethylammonium hydroxide, myristyltrimethylammonium chloride, myristyltrimethylammonium bromide, myristylammonium hydroxide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium hydroxide, octadecylto Examples include alkyl (carbon number: 10 to 22) trimethylammonium salts such as methylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium hydroxide, behenyltrimethylammonium chloride, behenyltrimethylammonium bromide, and behenyltrimethylammonium hydroxide. From the viewpoint of regularity, alkyltrimethylammonium salts having 14 to 18 carbon atoms are preferred.

で示される有機化合物を指し、テトラメトキシシラン（ＴＭＯＳ）、テトラエトキシシラン（ＴＥＯＳ）等が挙げられる。 As alkoxysilane,

And includes, for example, tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS).

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example.

Example 1
Dissolve 2.1 g of myristyltrimethylammonium chloride (C14 alkyltrimethylammonium salt) in 40 g of 0.5M hydrochloric acid, and after stirring at 25 ° C., add 4.3 g of tetraethoxysilane (TEOS), pH 2.0, Stir at 25 ° C. for 3 hours. Thereafter, 3.5 g of 25% ammonia solution was added and stirred at pH 9.0 and 25 ° C. for 1 hour. The preparation was transferred to a tray and dried at 70 ° C. for 24 hours. The obtained solid was fired at 580 ° C. for 10 hours to obtain 1.0 g of porous silica A of the present invention.

Example 2
After 2.1 g of cetyltrimethylammonium chloride (C16 alkyltrimethylammonium salt) was dissolved in 40 g of 0.5 M hydrochloric acid and stirred at 25 ° C., 4.3 g of tetraethoxysilane (TEOS) was added, pH 2.0, Stir at 25 ° C. for 3 hours. Thereafter, 3.5 g of 25% ammonia solution was added and stirred at pH 9.0 and 25 ° C. for 1 hour. The preparation was transferred to a tray and dried at 70 ° C. for 24 hours. The obtained solid was baked at 580 ° C. for 10 hours to obtain 1.0 g of porous silica B of the present invention.

Example 3
2.1 g of octadecyltrimethylammonium chloride (alkyltrimethylammonium salt having 18 carbon atoms) is dissolved in 40 g of 0.5 M hydrochloric acid, stirred at 25 ° C., 4.3 g of tetramethoxysilane (TMOS) is added, pH 2.0, Stir at 25 ° C. for 3 hours. Thereafter, 3.5 g of 25% ammonia solution was added and stirred at pH 9.0 and 25 ° C. for 0.5 hour. The preparation was subjected to suction filtration using a filter paper (No. 5C manufactured by Advantech), and the solid content was dried for an hour at 70 ° C. The obtained solid was calcined at 580 ° C. for 10 hours to obtain 1.4 g of porous silica C of the present invention Got.

Comparative Example 1
2.1 g of cetyltrimethylammonium chloride (alkyltrimethylammonium salt having 16 carbon atoms) is dissolved in 40 g of 2.0 M hydrochloric acid, stirred at 25 ° C., 4.3 g of tetraethoxysilane (TEOS) is added, pH is 0.1, Stir at 25 ° C. for 3 hours. Thereafter, 5.5 g of a 25% ammonia solution was added, and the mixture was stirred at pH 9.0 and 25 ° C. for 1 hour. The preparation was transferred to a tray and dried at 70 ° C. for 24 hours. The obtained solid was fired at 580 ° C. for 10 hours to obtain 1.0 g of porous silica a.

Comparative Example 2
After 2.1 g of cetyltrimethylammonium chloride (C16 alkyltrimethylammonium salt) was dissolved in 40 g of 0.5 M hydrochloric acid and stirred at 25 ° C., 4.3 g of tetraethoxysilane (TEOS) was added, pH 2.0, Stir at 25 ° C. for 3 hours. Thereafter, 5.5 g of a 25% ammonia solution was added to adjust the pH to 10.5, and the mixture was stirred at 25 ° C. for 1 hour. The preparation was transferred to a tray and dried at 70 ° C. for 24 hours. The obtained solid was calcined at 580 ° C. for 10 hours to obtain 1.0 g of porous silica b.

Comparative Example 3
36 g of cetyltrimethylammonium chloride (C16 alkyltrimethylammonium salt) was dissolved in 500 ml of ion-exchanged water at 65 ° C. (pH 11.0). This liquid was added to a mixed liquid of water glass No. 1 1418.4 g and ion-exchanged water 500 g, and stirred at 65 ° C. for 1 hour. The pH was adjusted to 8.5 by adding 80 g of 2M hydrochloric acid, and the mixture was stirred at 65 ° C. for 1 hour. The preparation was washed with ion-exchanged water, filtered, and the solid content was dried at 40 ° C. for 24 hours. The obtained solid was calcined at 580 ° C. for 10 hours to obtain 328.0 g of porous silica c.

After the porous silicas A, B, and C obtained in Examples 1 to 3 and the porous silicas a, b, and c obtained in Comparative Examples 1 to 3 were dried at 80 ° C. for 1 hour, an X-ray diffraction pattern Was measured, and the peak intensity ratio of d ₁₁₀ and d ₂₀₀ when the peak intensity of d ₁₀₀ was taken as ₁₀₀ was calculated. The results of the X-ray diffraction patterns of the porous silicas A, B and C of the present invention are shown in FIG. 1, and the results of the X-ray diffraction patterns of the comparative porous silicas a, b and c are shown in FIGS. 4 shows. Further, X when the ratio of the porous _d 100 of porous silica a~c silica A~C and _{comparative, d 110,} d ₂₀₀ and the peak intensity of _{(d 100} shown in Table 1 and 100 of the present invention Peak intensity ratio of line diffraction pattern). The X-ray diffraction pattern was measured with a fully automatic X-ray diffractometer (manufactured by RINT ULTIMAII Rigaku Corporation).

As shown in FIG. 1, the peaks of d ₁₀₀ , d ₁₁₀ , and d ₂₀₀ were observed for porous silicas A, B, and C. Further, as shown in Table 1, the porous silica _{A, B, d 100, d} 110, the ratio of _{d 200} of C _{is, d 100: d 110: d} 200 = 100: 5.0~20.0: 5 Within the range of .0 to 15.0.

As shown in FIG. 2 and FIG. 3, the peaks of d ₁₀₀ and d ₁₁₀ were observed for porous silica a and porous silica b, but the peak of d ₂₀₀ was not observed. Further, as shown in Table 1, the porous silica a, _{d 100,} d _110, the ratio of _{d 200} of _{b, d 100: d 110: d} 200 = 100: 5.0~20.0: 5.0 It was not in the range of ˜15.0.

As shown in FIG. 4, the ratio of d ₁₀₀ , d ₁₁₀ , d ₂₀₀ of the porous silica c is d ₁₀₀ : d ₁₁₀ : d ₂₀₀ = 100: 5.0 to 20.0: 5.0 to 15.0. It was within the range.

  For the porous silicas A, B, and C obtained in Examples 1 to 3 and the porous silicas a, b, and c obtained in Comparative Examples 1 to 3, the average pore diameter and ratio were measured by a known nitrogen adsorption measurement. The surface area was calculated. That is, the nitrogen adsorption measurement was performed using a gas adsorption amount measuring device (BELSORP18 Plus Nippon Bell Co., Ltd.) after vacuum suction treatment at 180 ° C. for 2 hours. The average pore diameter was calculated by a known BJH method, and the specific surface area was calculated by a known BET method.

The particle size distribution of the porous silicas A, B, and C obtained in Examples 1 to 3 and the porous silica c obtained in Comparative Example 4 was measured. FIG. 5 shows the results of porous silicas A, B, and C, and FIG. 6 shows the results of porous silica c. The particle size distribution was obtained by adding 100 mg of porous silica to 10 ml of ion-exchanged water and dispersing at 20 KHz, 200 W, 4.4 watt / cm ³ with an ultrasonic generator (Ultrasonic distributor / Tomy UD-200). This dispersion was measured using a laser diffraction / scattering particle size distribution analyzer (COULTER LS230, manufactured by Beckman Coulter, Inc.).

  As shown in FIG. 5, the average particle diameters of the porous silicas A, B and C were in the range of 50 to 500 nm.

  As shown in FIG. 6, the average particle diameter of the porous silica c was 4877 nm, and was not in the range of 50 to 500 nm.

  According to the present invention, porous silica having highly regular pores in the mesopore region and dispersed in a submicron order in a solvent can be provided, and its industrial utility value is great.

It is an X-ray diffraction pattern of porous silica A, B, C. It is an X-ray diffraction pattern of porous silica a. It is an X-ray diffraction pattern of porous silica b. It is an X-ray diffraction pattern of porous silica c. It is a figure which shows the average particle diameter of porous silica A, B, and C. It is a figure which shows the average particle diameter of the porous silica c.

Claims (3)

In the X-ray diffraction pattern, the peak intensity is represented by a ratio of d ₁₀₀ : d ₁₁₀ : d ₂₀₀ = 100: 5.0 to 20.0: 5.0 to 15.0, and the average particle size is 50 to 500 nm. The porous silica characterized by the above. A first step of dispersing alkoxysilane in a cationic surfactant solution of pH 1 to pH 3 and adding an alkali source to the dispersion to adjust the pH to 8.5 to 9.5, whereby a composite of silica and surfactant 2. The porous silica according to claim 1, wherein the porous silica is produced by a method comprising a second step of forming a surfactant and a third step of removing the surfactant from the obtained composite. The porous silica according to claim 2, wherein the alkali source added in the second step is ammonia.

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