Method for producing hydrophilized product

Abstract

A method for producing a hydrophilized product according to one aspect of the present invention comprises a step for hydrophilizing an inorganic oxide by subjecting an alkaline reaction solution containing water and an object to be treated having the inorganic oxide on the surface thereof to a hydrothermal treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for producing a hydrophilic treatment product. BACKGROUND

[0002] Oxide particles such as silica and alumina are widely used as inorganic fillers for electronic materials or resin parts for automobiles (for example, Patent Literature 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2020-132753 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, inorganic oxides are required to have high hydrophilicity.

[0008] An object of the present application is to provide a method for producing a novel hydrophilic treatment product capable of hydrophilizing inorganic oxides.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] One aspect of the present application is a method for producing a hydrophilic treatment product, comprising a step of hydrophilizing an inorganic oxide by subjecting an alkaline reaction liquid containing a treated object having the inorganic oxide on the surface and water to hydrothermal treatment.

[0011] [1] A method for producing a hydrophilic treatment product, comprising a step of hydrophilizing an inorganic oxide by subjecting an alkaline reaction liquid containing a treated object having the inorganic oxide on the surface and water to hydrothermal treatment.

[0012] [2] The method for producing a hydrophilic treatment product according to [1], wherein the inorganic oxide is alumina.

[0013] [3] The method for producing a hydrophilic treatment product according to [1] or [2], wherein the inorganic oxide is silica.

[0014] [4] The method for producing a hydrophilic treatment product according to any one of [1] to [3], wherein the inorganic oxide is ceria.

[0015] [5] The method for producing a hydrophilic treatment product according to any one of [1] to [4], wherein the hydrothermal treatment is performed at a temperature of 110 to 300°C.

[0016] [6] The method for producing a hydrophilic treatment object according to any one of [1] to [5], wherein the hydrothermal treatment is performed at a temperature of 110 to 190°C and a treatment time of 5 minutes to 24 hours.

[0017] [7] The method for producing a hydrophilic treatment object according to any one of [1] to [6], wherein the treatment object is a particle.

[0018] [8] The method for producing a hydrophilic treatment object according to any one of [1] to [6], wherein the treatment object is a semiconductor wafer.

[0019] Effects of the Invention

[0020] According to one aspect of the present application, there is provided a novel method for producing a hydrophilic treatment object capable of hydrophilizing an inorganic oxide. DETAILED DESCRIPTION

[0021] Hereinafter, the present application will be described in detail according to preferred embodiments thereof. However, the present application is not limited to the following embodiments.

[0022] In the present specification, the term "step" includes not only a single step but also a step which cannot be clearly distinguished from other steps as long as the desired function of the step is achieved. In the present specification, a numerical range indicated by "~" indicates a range including the numerical values recited before and after "~" as the minimum value and the maximum value, respectively. In the numerical range recited in stages in the present specification, the upper limit value or the lower limit value of the numerical range of a certain stage can be arbitrarily combined with the upper limit value or the lower limit value of the numerical range of another stage. In the numerical range recited in the present specification, the upper limit value or the lower limit value of the numerical range can be replaced with the value indicated in the examples. "A or B" includes either one of A and B, and can include both. In the present specification, the materials exemplified can be used alone or in combination of two or more, unless otherwise specified.

[0023] (Method for producing a hydrophilic treatment object)

[0024] The method for producing a hydrophilic treatment object according to the present embodiment includes a step of hydrophilizing an inorganic oxide by subjecting an alkaline reaction solution containing a treatment object having an inorganic oxide on the surface and water to hydrothermal treatment.

[0025] The area ratio of the inorganic oxide on the surface of the treatment object can be 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100%.

[0026] The shape of the object to be treated is not particularly limited as long as it can be accommodated in the airtight container and water and the alkali agent can contact the surface of the object to be treated. The shape of the object to be treated can be, for example, a cylindrical shape, a columnar shape, a spherical shape, an indefinite shape, or a plate shape. The object to be treated can be a particle. The object to be treated can be a semiconductor wafer.

[0027] The inorganic oxide is composed of an element having an electronegativity lower than that of oxygen and forming at least one ion having a valence of two or more.

[0028] As the inorganic oxide, for example, there can be mentioned silicon dioxide, cerium dioxide, aluminum oxide, titanium dioxide, zirconium oxide, magnesium oxide, yttrium oxide, zinc oxide, iron oxide, tin oxide, scandium oxide, vanadium oxide, and chromium oxide. The inorganic oxide can be a composite oxide composed of two or more metals. As such a composite oxide, for example, there can be mentioned lithium titanate, barium titanate, and magnesium-aluminum oxide. The inorganic oxide can be produced by a melting method, a sol-gel method, a liquid phase method, or the like.

[0029] The reaction liquid is alkaline. Alkaline means that the pH is more than 7.0. The reaction liquid can be adjusted to be alkaline by adding an alkali agent to water. Since the saturated vapor pressure of the alkali agent has a tendency to reduce the pressure resistance of the airtight container, it is preferable to be lower than water. As the alkali agent having a saturated vapor pressure higher than water, for example, there can be mentioned ammonia and amines such as methylamine. As the alkali agent having a saturated vapor pressure lower than water, for example, there can be mentioned metal hydroxides such as potassium hydroxide, sodium hydroxide, and aluminum hydroxide. Also, a solid alkali catalyst such as zeolite subjected to alkali treatment on the surface can be used as the alkali agent.

[0030] The pH of the reaction liquid is more than 7.0, and can be 8.0 or more, 9.0 or more, 10.0 or more, or 11.0 or more, and can be 13.0 or less.

[0031] The hydrothermal treatment can be performed by sealing the object to be treated, water, and an alkali agent in an airtight container having pressure resistance, and heating at a temperature of more than 100°C in a closed state. By heating the reaction liquid containing the object to be treated and water in the airtight container, the inside of the airtight container becomes a heating and pressurizing environment, and the hydrothermal treatment (hydrothermal synthesis) is performed.

[0032] The hydrothermal treatment can be performed by supplying water vapor (steam) from the outside to the airtight container. By supplying water vapor from the outside, the temperature and pressure in the airtight container can be increased in a short time, and the hydrothermal treatment environment can be easily formed and maintained. The supply of water vapor can be performed using, for example, a boiler. The supply of water vapor can be performed in combination with the method of heating the reaction liquid containing the object to be treated and water in the airtight container. The amount of water vapor supplied is appropriately adjusted so that the inside of the airtight container becomes a predetermined temperature and pressure.

[0033] The hydrothermal treatment can be performed while stirring the reaction liquid. As the pressure-resistant closed container, a publicly known container that can be used for hydrothermal treatment can be used without particular limitation. As the pressure-resistant closed container, for example, an autoclave can be used.

[0034] The content of the treated substance in the reaction liquid is not particularly limited as long as a sufficient amount of water for the hydrothermal treatment is ensured, and can be 10 parts by volume or more, 20 parts by volume or more, or 50 parts by volume or more, and can also be 300 parts by volume or less, 200 parts by volume or less, or 100 parts by volume or less, with respect to 100 parts by volume of water. The content of the treated substance in the reaction liquid is preferably 100 parts by volume or less, because this avoids excessively high viscosity of the reaction liquid, thereby facilitating stirring and having a tendency to improve the processing efficiency.

[0035] The reaction conditions for the hydrothermal treatment are not particularly limited, and can be set to, for example, 110 to 300°C and 0.5 minutes to 24 hours. If the reaction temperature is 110°C or higher, there is a tendency for the hydrothermal reaction to occur more easily and favorably, and if it is 300°C or lower, there is a tendency for the ion concentration in the reaction liquid to be high and for the reaction to proceed in a short time. The reaction temperature is preferably 170°C or higher, preferably 260°C or lower, and more preferably 190°C or lower. The reaction time is preferably 5 minutes to 24 hours, more preferably 0.5 to 24 hours, and further preferably 5 to 15 hours. If the reaction time is 24 hours or less, there is a tendency to easily achieve a balance between the progress of the reaction and the cost.

[0036] From the viewpoint of further improving the hydrophilicity, it is preferable that the hydrothermal treatment be performed under conditions of low temperature (for example, less than 250°C) and long time (for example, 1 hour or more). If the reaction temperature is less than 250°C, there is a tendency to easily prevent bumping of the reaction liquid upon cooling after the reaction, thereby being able to suppress a decrease in the yield of the hydrophilized treated substance due to scattering of the reaction liquid to the outside of the container upon bumping. When the reaction temperature is less than 250°C, there is a tendency to be able to shorten the cooling time of the reaction liquid, thereby improving the work efficiency. Furthermore, by the reaction time being 1 hour or more, there is a tendency to be able to sufficiently perform the hydrophilization reaction even at low temperature.

[0037] The pressure in the container at the time of the hydrothermal treatment can be the saturated vapor pressure corresponding to the above-described reaction temperature or more, but from the viewpoint of the pressure resistance of the apparatus, the saturated vapor pressure is preferable. In the case of supplying water vapor into the closed container, it is preferable to supply the saturated water vapor at the above-described reaction temperature.

[0038] (Evaluation of Hydrophilicity Based on Hansen Solubility Parameter (HSP))

[0039] In the present specification, the hydrophilization of the inorganic oxide means that the polarizability term (δ p1) and hydrogen bonding term (δ h1 ) is increased by 2 or more.

[0040] Hitherto, as a method for evaluating the hydroxyl group concentration or the hydrophilicity of the surface of an inorganic oxide, there are known a surface infrared spectroscopy measurement method, a titration method based on a metal hydride, an organic metal compound, and the like, but there are problems of low reproducibility or poor quantitativeness due to precision, required humidity, strictness of moisture amount management, and the like. Therefore, as a result of intensive studies by the inventors, it has been found that the HSP measurement method shown below becomes a hydrophilicity evaluation method capable of satisfying quantitativeness and reproducibility.

[0041] Specifically, since the δ d , δ p , and δ h of a common substance are known from a database or the like, for example, the δ d , δ p , and δ h of a desired substance can be obtained by referring to the database. The parameters of a substance not registered in the database can be calculated using, for example, a computer software such as HSPiP (Hansen Solubility Parameter in Practice; written by Prof. Steven Abbott and Dr. Yamamoto Hiroshi).

[0042] For example, the δ d1 , δ p1 , and δ h1 of an inorganic oxide particle can be calculated by the following procedure. First, 16 kinds of evaluation solvents of which the parameters (δ d , δ p , and δ h ) are known are prepared. Next, a dispersibility test of the particle of the evaluation object with respect to each of the evaluation solvents is performed, and it is determined which of each of the evaluation solvents is "a solvent excellent in dispersibility" and "a solvent poor in dispersibility". The dispersibility test can be performed by the method shown in the following examples. Next, after each of the evaluation solvents is plotted in a three-dimensional space (Hansen space) with the δ d , δ p , and δ h as the coordinate axes, a virtual spherical ball is made in the three-dimensional space so as not to include all of the "solvents poor in dispersibility" and to include all of the "solvents excellent in dispersibility". Then, the δ d , δ p , and δ h of the center of the spherical ball are obtained as the δ d1 , δ p1 , and δ h1 of the particle.

[0043] δ d1 , δ p1 and δ h1 The particle size varies depending on the type of material, particle size, particle size distribution (coefficient of variation of particle size), surface treatment content (type of surface treatment agent, amount of surface treatment agent used, surface treatment method, etc.). For example, the larger the particle size, the higher the δ d1 There is a tendency to increase, while δ p1 and δ h1 There is a tendency to decrease. In addition, the larger the coefficient of variation of particle size, the greater the p1 There is a tendency to increase, while δ h1 There is a tendency to decrease. The δ of the surface treated particles d1 , δ p1 and δ h1 The entire surface-treated particle is taken as the object, taking into account the influence of the surface treatment. d1 , δ p1 and δ h1 , the value at 25°C can be used.

[0044] Example

[0045] Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0046] (Example 1)

[0047] Alumina particles (manufactured by Sumitomo Chemical Co., Ltd., product name "AA04") were prepared as the treated material. Scanning electron microscope (SEM) imaging revealed the particle size D50 (hereinafter referred to as "particle size A") and particle size D100 of the particles. Particle size A was 0.4 μm.

[0048] The alumina particles (particle diameter A: 0.4 μm) 18 g were dispersed in ultrapure water 162 g, and while confirming the pH of the dispersion liquid using a pH meter (manufactured by As One Corporation), a prescribed amount of sodium hydroxide was added, whereby a reaction liquid 1 having a pH of 12 was prepared. This was enclosed in a Teflon (registered trademark) container having a capacity of 200 ml, and the Teflon (registered trademark) container was further housed in a stainless steel pressure-resistant container, and the pressure-resistant container was closed. Inside the closed pressure-resistant container, while stirring the solution in the Teflon (registered trademark) container at a rotation speed of 700 rpm using a magnetic stirrer, heating was performed by a heater, and the temperature of the reaction liquid was made to be 180°C. After reaching 180°C, while continuing the stirring, hydrothermal treatment was performed at 180°C for 5 hours. Then, the heating and stirring were stopped, and natural cooling to room temperature (25°C) was performed. In addition, the maximum reached temperature of the reaction liquid during the hydrothermal treatment was 181°C. After cooling, the solution and solid components in the Teflon (registered trademark) container were extracted into a beaker, ultrapure water was added to dilute to 800 ml, and the mixture was left overnight to precipitate the alumina particles, and the supernatant was separated using a dropper. Dilution and separation were repeated until the pH of the supernatant became 7. Then, the supernatant was dried using an oven at 130°C for 3 hours, and 15.6 g of a powder-like basic hydrothermally reacted alumina 1 was obtained.

[0049] (Example 2)

[0050] Silica particles (manufactured by NIPPON SHOKUBAI CO., LTD., product name "KE-S50") were prepared. The particle diameter D50 (hereinafter, referred to as "particle diameter A") and the particle diameter D100 of the particles were obtained from real image observation using a scanning electron microscope (SEM). The particle diameter A was 0.5 μm. Except that the silica particles (manufactured by NIPPON SHOKUBAI CO., LTD., product name "KE-S50", particle diameter A: 0.5 μm) were used instead of the alumina particles, a powder-like basic hydrothermally reacted silica 1 was obtained in the same manner as in Example 1.

[0051] (Comparative Example 1)

[0052] The untreated alumina particles were used as the sample of Comparative Example 1.

[0053] (Comparative Example 2)

[0054] An alumina particle (manufactured by Sumitomo Chemical Co., Ltd., product name "AA04", particle diameter A: 0.4 μm) 18 g was dispersed in ultrapure water 162 g, and while confirming the pH of the dispersion liquid using a pH meter (manufactured by As One Corporation), a prescribed amount of sulfuric acid was added, whereby a reaction liquid 2 having a pH of 7 was prepared. Except for using the reaction liquid 2 instead of the reaction liquid 1, the hydrothermally reacted alumina particle 2 was obtained in the same manner as in Example 1.

[0055] (Comparative Example 3)

[0056] The untreated silica particle was used as a sample of Comparative Example 3.

[0057] (Comparative Example 4)

[0058] A silica particle (manufactured by NIPPON SHOKUBAI CO., LTD., product name "KE-S50", particle diameter A: 0.5 μm) 18 g was dispersed in ultrapure water 162 g, whereby a reaction liquid 3 was prepared. The pH of the reaction liquid 3 was 6.9. Except for using the reaction liquid 3 instead of the reaction liquid 1, the hydrothermally reacted silica particle 2 was obtained in the same manner as in Example 1.

[0059] < Evaluation Method >

[0060] (Measurement of the Hansen solubility index of the sample)

[0061] Next, 16 kinds of organic solvents 20 mL were put in each of 16 containers (screw bottles) after 0.02 g of the particle was put in each of the containers, whereby test liquids (particle content: about 0.1 mass%) were prepared. As the 16 kinds of organic solvents, MIBK (methyl isobutyl ketone), toluene, methanol, cyclohexanol, acetone, acetonitrile, formamide, benzyl benzoate, dimethyl sulfoxide, ethyl acetate, ethanol, acetic anhydride, γ-butyrolactone, MEK (methyl ethyl ketone), 1-butanol, and cyclohexane were used. The test liquids were subjected to dispersion treatment for 5 minutes using an ultrasonic dispersion device (manufactured by AS ONE Co., Ltd., product name "VS-D100"). Next, the particle size distribution (cumulative particle size distribution, volume distribution) of the particle in the test liquid was measured using a particle size distribution meter (manufactured by Shimadzu Corporation, product name "SALD-7500"). For the case where the above 16 kinds of organic solvents were used, the particle diameter D50 (hereinafter, referred to as "particle diameter B") was obtained based on the measurement results of the particle size distribution, respectively. In addition, the particle size distribution of the standard particle (MBP1-10) whose particle size distribution was determined in advance was measured, and it was confirmed that the measurement content was appropriate.

[0062] Based on the measurement results of the particle size distribution, the coefficient of variation (CV) of the particle size was obtained for each of the 16 organic solvents. The case where the coefficient of variation was 20 or more was judged to be a polydisperse state, and the case where the coefficient of variation was less than 20 was judged to be a monodisperse state. For the 16 organic solvents, the following criteria were used to determine which was a "poorly dispersible solvent" and which was an "excellent dispersible solvent".

[0063] For the criterion of aggregation in the monodisperse state, a particle size twice the particle size A (assuming the particle size when two particles are in contact) was used as a threshold value, and the organic solvent for which the particle size B was equal to or greater than the threshold value was judged to be a "poorly dispersible solvent", and the organic solvent for which the particle size B was less than the threshold value was judged to be an "excellent dispersible solvent".

[0064] On the other hand, for the criterion of aggregation in the polydisperse state, since the distribution of the particle size is wide, from the viewpoint of desiring to set a criterion that easily targets aggregated particles, the particle size D100 was used as a threshold value, and the organic solvent for which the particle size B was equal to or greater than the threshold value was judged to be a "poorly dispersible solvent", and the organic solvent for which the particle size B was less than the threshold value was judged to be an "excellent dispersible solvent".

[0065] Next, using the analysis software HSPiP (Hansen Solubility Parameter in Practice; written by Prof. Steven Abbott and Dr. Yamamoto Hiroshi), the 16 organic solvents were plotted in a three-dimensional space (Hansen space) with δ d , δ p , and δ h as the coordinate axes. As the δ d , δ p , and δ h of each organic solvent, the values in the database of the analysis software were used.

[0066] Next, in the three-dimensional space, a virtual spherical ball was created that did not include any of the "poorly dispersible solvents" and included all of the "excellent dispersible solvents". Then, the δ d , δ p , and δ h of the center of the spherical ball were obtained as the δ d1 , δ p1 , and δ h1 of the particles. The δ d1 , δ p1 , and δ h1 of the particles in the examples and comparative examples are shown in Table 1.

[0067] [Table 1]

[0068]

[0069] Of the 3 terms of HSP, the term that affects hydrophilicity is δ p1 derived from polar force and δ h1 derived from hydrogen bond force. If the value of at least one of these 2 terms increases by 2 or more, it is considered that the hydroxyl group of the inorganic oxide increases, and thus it is possible to determine that the inorganic oxide has been hydrophilized.

[0070] When comparing Example 1 in which the treated substance is alumina particles with Comparative Example 1, since the values of δ p1 and δ h1 are both increased and δ p1 is increased by 2 or more in Example 1, it is known that the alumina particles have been hydrophilized after the hydrothermal treatment.

[0071] On the other hand, when comparing Comparative Example 1 and Comparative Example 2, the HSP hardly changes, and thus it is known that the inorganic oxide is not hydrophilized when the hydrothermal treatment is performed under neutral conditions.

[0072] When comparing Example 2 in which the treated substance is silica particles with Comparative Example 3, δ p1 and δ h1 in δ h1 of Example 2 are significantly increased, and thus it is known that the silica particles have been hydrophilized after the hydrothermal treatment.

[0073] On the other hand, when comparing Comparative Example 3 and Comparative Example 4, the HSP hardly changes, and thus it is known that the inorganic oxide is not hydrophilized when the hydrothermal treatment is performed under acidic conditions.

Claims

1. A method for producing a hydrophilic treatment product, comprising the steps of: hydrophilizing an inorganic oxide on a surface of a treatment target by subjecting an alkaline reaction solution containing the treatment target and water to hydrothermal treatment.

2. The method for producing a hydrophilic treatment product according to claim 1, wherein the inorganic oxide is alumina.

3. The method for producing a hydrophilic treatment product according to claim 1 or 2, wherein the inorganic oxide is silica.

4. The method for producing a hydrophilic treatment product according to any one of claims 1 to 3, wherein the inorganic oxide is ceria.

5. The method for producing a hydrophilic treatment product according to any one of claims 1 to 4, wherein the hydrothermal treatment is performed at a temperature of 110 to 300°C.

6. The method for producing a hydrophilic treatment product according to any one of claims 1 to 5, wherein the hydrothermal treatment is performed at a temperature of 110 to 190°C and for a period of 5 minutes to 24 hours.

7. The method for producing a hydrophilic treatment product according to any one of claims 1 to 6, wherein the treatment target is a particle.

8. The method for producing a hydrophilic treatment product according to any one of claims 1 to 6, wherein the treatment target is a semiconductor wafer. ​ ​ ​ ​ ​ ​ ​ ​

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