WO2010032851A1

WO2010032851A1 - Method for producing hydrophilized microparticles, and hydrophilized microparticles produced by the method

Info

Publication number: WO2010032851A1
Application number: PCT/JP2009/066442
Authority: WO
Inventors: 藤田　一郎; 竹林　仁; 順司高田; 佐々木　令晋; 和明松本; 勇人池田; 浅子　佳延
Original assignee: 東洋炭素株式会社; 株式会社日本触媒
Priority date: 2008-09-19
Filing date: 2009-09-18
Publication date: 2010-03-25
Also published as: CN102159625B; KR20110069785A; TWI464186B; CN102159625A; JP5698978B2; TW201026726A; JPWO2010032851A1

Abstract

Disclosed is a method for producing vinyl polymer microparticles each having a highly hydrophilized surface without deteriorating excellent physical properties including mechanical properties and other properties including particle-size-controlling properties inherent in vinyl polymer microparticles. Also disclosed are the hydrophilized particles. Specifically disclosed is a method for producing hydrophilized microparticles, which is characterized by comprising contacting a mixed gas essentially comprising a fluorine gas and a gas of a compound containing an oxygen atom with base particles to render the surfaces of the base particles hydrophilic, wherein the base particles comprise vinyl polymer microparticles having a mass average particle diameter of 1000 μm or less and the mixed gas contains the fluorine gas at a concentration of 0.01 to 1.0 vol%.

Description

Method for producing hydrophilized fine particles and hydrophilized fine particles obtained by the method

The present invention relates to a method for producing hydrophilic fine particles by subjecting the surface of base particles to hydrophilicity treatment.

Vinyl-based (co) polymer fine particles are usually produced by radical polymerization using a raw material such as a (meth) acrylic monomer that is a polymerization raw material or a vinyl monomer composition such as styrene as a raw material. Or by adding inorganic components or non-polymerizable components to the vinyl monomer composition, the mechanical strength, heat resistance, optical properties, surface shape, porosity, etc. of the fine particles Various physical properties can be controlled. The polymerization method can be appropriately selected from suspension polymerization, emulsion polymerization, seed polymerization, dispersion polymerization, etc., and vinyl polymer fine particles having a controlled particle diameter and particle size distribution are produced over a wide range. be able to. Vinyl polymer fine particles have been used in a wide range of industrial fields such as paint additives and film additives because of their ease of control of various properties as described above and economic significance among polymer fine particles. .

In recent years, the surface of vinyl polymer fine particles has been made hydrophilic with the background of water-based paints based on environmental issues, etc., and with the aim of expanding into new application fields that can make use of the excellent properties of vinyl polymer fine particles. Attempts have been made.

The following methods are known as the hydrophilic treatment of such fine particles. For example, Patent Document 1 describes a method of reacting a crosslinked polymer fine particle having a reactive functional group on the surface with a modified or unmodified polyethylene glycol having a reactive group capable of causing a chemical reaction with these functional groups. Has been. In this technique, when the modified or unmodified polyethylene glycol is reacted, the fine particles are liable to cause secondary aggregation. In addition, the reactive functional group of the crosslinked polymer fine particle is introduced into the polymer by a (meth) acrylic monomer having a reactive functional group. However, when the concentration of the functional group-containing monomer is increased, fine particles and coarse particles There is a problem that generation, secondary aggregation, etc. are likely to occur, and it becomes difficult to control the particle size distribution, and the mechanical properties of the particles are deteriorated. For this reason, it was difficult to introduce a reactive functional group at a high concentration on the surface of the fine particles. Moreover, since it is a chemical surface treatment reaction, it is not possible to obtain fine particles that are uniformly hydrophilized. As a result, there has been a problem that fine particles having a hydrophilic group uniformly and at a high density cannot be obtained.

Patent Document 2 describes a technique for making a surface of fluororesin particles hydrophilic by adsorbing a surfactant. Since this technique simply adsorbs the surfactant on the surface of the fluororesin particles, it is difficult to permanently maintain the hydrophilic state and the degree of hydrophilicity is low.

Patent Document 3 describes a method of hydrophilizing by dispersing fine particles in ozone water in which ozone gas is dissolved in water. In this method, there is a problem that the strength and heat resistance of the particles are lowered when sufficiently hydrophilized.

Since all of the above Patent Documents 1 to 3 are treatments in a liquid phase, secondary aggregation of fine particles is likely to occur, and uniform treatment cannot be performed, so that it is difficult to obtain fine particles having a high degree of hydrophilicity.

Patent Documents 4 and 5 describe a method of performing a hydrophilic treatment using ozone gas. Patent Document 6 describes a method for hydrophilizing the surface of fine particles by a low-temperature plasma treatment using argon gas. In these methods, electrostatic aggregation easily occurs due to treatment in a charged gas, and it is difficult to uniformly hydrophilize the particle surface.

JP-A-5-1106 JP 2005-336241 A JP 2007-326935 A JP 2001-212447 A JP 2005-239915 A JP 2007-184278 A

In the present invention, vinyl having a high degree of hydrophilicity on the surface without impairing the excellent mechanical properties, various physical properties such as heat resistance, properties such as controllability of particle diameter, etc. possessed by the vinyl polymer fine particles as described above. The production method for obtaining the polymer fine particles and the provision of such hydrophilized fine particles were raised as problems.

In order to solve the above-mentioned problems, the present inventors diligently studied the method for hydrophilizing vinyl polymer fine particles, and as a result, by treating the vinyl polymer fine particles in a specific gas atmosphere, the vinyl polymer fine particles The present inventors have found that particles having extremely high hydrophilicity can be obtained without impairing excellent properties such as mechanical properties of the present invention.

The method for producing hydrophilized fine particles of the present invention that has solved the above-described problem is that a base material is subjected to a treatment in which a mixed gas containing a fluorine gas and a gas containing a compound containing oxygen atoms is brought into contact with the base material. A method for producing hydrophilized microparticles by hydrophilizing the surface of the particles, wherein vinyl polymer microparticles having a mass average particle diameter of 1000 μm or less are used as substrate particles, and the fluorine gas concentration in the mixed gas is 0.01 to It is characterized by 1.0% by volume.

As the compound gas containing oxygen atoms, oxygen gas is preferable. Moreover, it is preferable to perform the process which makes it contact with a water | moisture content after the process which makes the said mixed gas contact the base material particle | grains. As this water | moisture content, alkaline aqueous solution and / or water and / or water vapor | steam are preferable.

The present invention includes hydrophilized fine particles obtained by the above production method.

In the production method of the present invention, the surface of the vinyl polymer fine particles can be made uniform and highly hydrophilic without impairing the excellent mechanical properties of the vinyl polymer fine particles. In addition, this production method is a simple method and can be highly hydrophilized in a short time, so that it is excellent in economic efficiency. Therefore, the production method of the present invention can provide vinyl polymer fine particles having a uniform and highly hydrophilic surface at low cost.

In the production method of the present invention, the surface of the base particle is hydrophilized by subjecting the base particle to contact with a mixed gas that essentially contains a fluorine gas and a compound gas containing oxygen atoms. By this treatment, it is considered that hydrogen bonded to carbon is substituted with oxygen and fluorine to become —C (F) ═O, and then a part or all thereof is converted to a carboxyl group. For this reason, a large number of —C (F) ═O and / or carboxyl groups are generated in the vicinity of the surface of the hydrophilized fine particles, and the hydrophilicity is remarkably increased. Further, along with the generation of the above-mentioned —C (F) ═O and carboxyl group, a reaction in which CH bonds in a part of the particle skeleton are converted into CF bonds also occurs. The presence of these functional groups and bonds can be confirmed by an X-ray photoelectron analyzer (ESCA) or the like.

It is preferable to perform a treatment of bringing the mixed gas into contact with moisture after the treatment of bringing the mixed gas into contact with the substrate particles. Upon contact with moisture, —C (F) ═O is more efficiently converted to a carboxyl group. As water, an alkaline aqueous solution and / or water and / or water vapor are preferable.

The surface of the hydrophilized fine particles obtained by the production method of the present invention has —C (F) ═O and / or a carboxyl group, and in addition to these groups on the surface or inside of the particle, As the fluorine component, a fluorine component covalently bonded to hydrocarbon carbon (also referred to as covalent bond fluorine) may be included. Since the covalently bonded fluorine has an effect of suppressing secondary aggregation between particles by coexisting with —C (F) ═O and / or a carboxyl group, it is preferably present even in a trace amount.

Further, the hydrophilized fine particles obtained by the production method of the present invention may have hydrogen fluoride (HF) attached as a fluorine component. Since this HF may be harmful in handling the hydrophilized fine particles of the present invention, its content is preferably as small as possible. More preferably, no HF is attached.

These fluorine components can be distinguished by the eluting fluorine content and the non-eluting fluorine content. That is, in the dissolution test described later, fluorine ionized and eluted in the solvent is referred to as eluting fluorine, and the content thereof is defined as the eluting fluorine content. The eluting fluorine includes fluorine derived from the above-mentioned attached (free) hydrogen fluoride and fluorine derived from —C (F) ═O.

On the other hand, in the dissolution test, fluorine that cannot be eluted is non-eluting fluorine, and its content is the non-eluting fluorine amount. The non-eluting fluorine usually corresponds to the above-described covalently bonded fluorine, but may contain a free fluorine component that is incorporated into the particles and cannot be eluted.

The eluting fluorine content and the non-eluting fluorine content are expressed in terms of fluorine atom content (mg / g) contained per 1 g of particles.

As a result of examining the safety and characteristics of the hydrophilized fine particles, it is preferable that non-eluting fluorine exists to some extent. Specifically, the range of 0.1 to 50 mg / g is preferable because the above-described effect of suppressing secondary aggregation is exhibited. However, if the amount is too large, the hydrophilicity may be insufficient or the mechanical properties of the particles may be deteriorated. A more preferable non-eluting fluorine content is 1 to 40 mg / g, and further preferably 2 to 20 mg / g.

On the other hand, the eluting fluorine content is preferably small or absent when handling the hydrophilized fine particles, and specifically, it is preferably less than 1 mg / g. It is more preferably 0.5 mg / g or less, further preferably 0.2 mg / g or less, still more preferably 0.1 mg / g or less, and particularly preferably 0.01 mg / g or less.

The degree of hydrophilicity can be expressed by an acid value (KOH neutralization amount: mgKOH / g). The acid value of the hydrophilized fine particles of the present invention is preferably 0.05 mgKOH / g or more. If it is less than 0.05 mgKOH / g, the dispersibility in an aqueous medium may be insufficient. The acid value is more preferably 0.1 mgKOH / g or more, and further preferably 1 mgKOH / g or more. The acid value of the hydrophilized fine particles is defined as the amount (mg) of KOH required for neutralizing 1 g of particles, and is measured by the method described later. The substrate particles are highly hydrophobic and do not get wet with water, so that they cannot be dispersed in an aqueous medium and the acid value cannot be measured. Moreover, when the alkali washing mentioned later is performed, the hydrogen atom of the carboxyl group produced | generated by the base particle is substituted by the alkali metal atom. Therefore, it is impossible to evaluate the degree of hydrophilicity by the acid value in the hydrophilized fine particles after alkali washing.

The degree of hydrophilicity of the particles can also be expressed by the degree of hydrophobicity, and the degree of hydrophobicity of the particles obtained by the method of the present invention is preferably 10 or less, and most preferably 0. The degree of hydrophobicity can be determined as follows.

[Hydrophobicity]
Put 50 cc of ion-exchanged water in a 200 cc glass beaker with a stirrer on the bottom, float 0.2 g of particles on the water surface, sink the tip of the burette in the water in the beaker, and gently rotate the stirrer 5 minutes after the addition of the particles, methanol is gradually introduced from the burette. Methanol is continuously introduced until the total amount of particles on the water surface is completely submerged in water, the amount of methanol introduced (cc) when the particles are completely submerged in water is measured, and the degree of hydrophobicity is determined based on the following equation.
Hydrophobic degree (%) = methanol introduction amount (cc) × 100 / {amount of water (cc) + methanol introduction amount (cc)}

Here, before adding methanol from the burette, when the particles floating on the water surface completely sink in the water, it was determined that the degree of hydrophobicity was zero.

It should be noted that the preferred form and range of the shape, average particle diameter, CV value of the particle diameter, and mechanical properties of the hydrophilized fine particles are the same as the preferred form and range in the description of the base particle described later.

[Hydrophilic treatment]
The hydrophilization treatment is not particularly limited as long as the base material particles and the mixed gas are in contact with each other. However, a method of introducing the mixed gas into a container that can hold the base material particles and treating the base particles in a sealed state (sealing) A contact method) or a method in which a mixed gas is circulated and continuously supplied in a container capable of holding substrate particles (continuous supply method) is preferable.

In the treatment, it is preferable to increase the contact efficiency between the mixed gas and the base material particles, and to make the mixture uniformly hydrophilic in a short time. In order to increase the contact efficiency, it is preferable to diffuse the mixed gas into the processing container, and examples thereof include a method in which the mixed gas is stirred in a stream using a stirring device such as a fan, or a method in which base particles are spread thinly on a pallet or the like. . Moreover, you may stir a base particle, The method etc. which rotate a processing container using a drum rotary apparatus etc., or make a base particle flow with a stirrer etc. are mentioned. A plurality of these contact efficiency improving means may be used in combination.

When the base particles are spread thinly on a pallet or the like, the thickness of the base particle layer is set to 2 mm or less in the processing container in order to perform the hydrophilic treatment uniformly and without variation among the particles. It is preferable to load. A more preferable particle layer thickness is 0.5 mm or less.

The concentration of fluorine gas in the mixed gas is 0.01 to 1.0% by volume. If the fluorine gas concentration is less than 0.01% by volume, there may be particles that are insufficiently hydrophilized. In view of excellent uniformity of the hydrophilization treatment, the fluorine gas concentration is preferably 0.08% by volume or more. When the concentration of the fluorine gas is set to 1.0% by volume or less, even if it is white or colored, there is little. More preferably, it is 0.3 volume% or less.

In the mixed gas, the gas of the compound containing oxygen atoms is an essential component together with the fluorine gas. Preferred examples of the compound gas containing oxygen atoms include oxygen, sulfur dioxide, carbon dioxide, carbon monoxide, and nitrogen dioxide. Among these, oxygen gas is preferable in terms of high hydrophilization efficiency even under mild processing conditions. As the mixed gas, an inert gas such as nitrogen, helium, or argon can be used in addition to the fluorine gas and the compound gas containing oxygen atoms. In addition, it is preferable to use nitrogen gas as an inert gas from the viewpoint of preventing dust explosion in the treatment in the gas phase and performing the hydrophilic treatment industrially and safely. Accordingly, the mixed gas preferably has a composition comprising a fluorine gas, a compound gas containing oxygen atoms, and an inert gas, and more preferably a mixed gas containing fluorine gas, oxygen gas and nitrogen gas.

If the gas concentration of the compound containing oxygen atoms in the mixed gas is 0.1 vol% to 99.99 vol%, the base particles that are the object of the present invention can be hydrophilized. When the gas concentration of the compound containing oxygen atoms is less than 0.1% by volume, there is a possibility that particles having insufficient hydrophilicity exist. In order to obtain particles (powder) having a uniform degree of hydrophilization, and in order to obtain highly hydrophilic particles in a short time, the gas concentration of the compound containing oxygen atoms is 0.1% by volume. It is preferable that the amount be 0.5% by volume or more. On the other hand, the high concentration of oxygen-containing compound gas does not adversely affect the hydrophilization of the particles, but the reason why dust explosion can be prevented in the hydrophilization treatment and the hydrophilization treatment can be performed safely. Is preferably 10% by volume or less, more preferably 5% by volume or less.

When an inert gas is used as a component of the mixed gas, the concentration of the inert gas is not particularly limited, and may be appropriately selected within a range that does not impair the effect of the hydrophilization treatment with a fluorine gas and a compound gas containing oxygen atoms. . Usually, 99 volume% or less is preferable. If it exceeds 99% by volume, there is a possibility that particles having insufficient hydrophilicity may exist. In addition, the concentration of the inert gas is preferably 90% by volume or more, and more preferably 94% by mass or more from the reason that the occurrence of dust explosion in the hydrophilic treatment can be suppressed and the hydrophilic treatment can be performed safely.

When the partial pressure of the fluorine gas in the mixed gas is 8 Pa (0.06 Torr) or more, the uniformity of the hydrophilic treatment is excellent, which is preferable. More preferably, it is 24 Pa (0.18 Torr) or more, and more preferably 64 Pa (0.48 Torr) or more. From the viewpoint of suppressing the decomposition and coloring of the vinyl polymer skeleton due to the hydrophilic treatment, the partial pressure of the fluorine gas is preferably 1000 Pa (7.5 Torr) or less, more preferably 700 Pa (5.25 Torr) or less. .

In the case of using oxygen gas as a component of the mixed gas, the partial pressure of oxygen gas is preferably 70 Pa (0.53 Torr) to 85000 Pa (637.6 Torr) from the viewpoint of performing the hydrophilic treatment uniformly. From the viewpoint of industrially and safely hydrophilizing treatment, it is preferably 70 Pa to 7998 Pa (60 Torr), and more preferably 70 Pa to 3999 Pa (30 Torr). The preferable range is the same with respect to the partial pressure of the gas of the compound containing an oxygen atom.

When nitrogen gas is used as a component of the mixed gas, the partial pressure of the nitrogen gas is preferably 3199 Pa (24 Torr) to 79180 Pa (594 Torr), more preferably 71918 Pa from the viewpoint of industrially and safely hydrophilizing treatment. (540 Torr) to 79180 Pa (594 Torr). In the case of using other inert gas, the preferable range of the partial pressure of the other inert gas is the same.

The total pressure of the mixed gas is preferably 101.3 kPa (760 Torr) or less in order to safely perform the hydrophilic treatment. If it exceeds 101.3 kPa, the mixed gas may leak out of the container.

In the case of the sealed contact type, the ratio of the mixed gas to the base particles is preferably 30 L to 4000 L, more preferably 1000 L to 3000 L, in terms of normal temperature and normal pressure, with respect to 1 kg of the base particles. preferable. In the case of the continuous supply type, it is preferable to supply the total flow rate from 30 L to 15000 L, more preferably from 1000 L to 10000 L, in terms of normal temperature and normal pressure, with respect to 1 kg of the base particles.

Specifically, in the case of the sealed contact type, the base particles put in a container that can be sealed as it is or put in a container are decompressed, and after reducing the pressure, the mixed gas is introduced and the treatment is performed for a predetermined time. If moisture remains, HF is generated and dangerous. Therefore, it is preferable to sufficiently evacuate when decompressing. In the case of the continuous supply type, the mixed gas may be introduced for a predetermined time.

In the case of the sealed contact type, the inside of the chamber may be preheated before introducing the mixed gas. The reaction temperature is preferably about −20 ° C. to 200 ° C., more preferably about 0 ° C. to 100 ° C., and further preferably 10 ° C. to 40 ° C. If the reaction temperature exceeds 200 ° C, the vinyl polymer particles may be decomposed. On the other hand, if the reaction temperature is lower than -20 ° C, the hydrophilization treatment may be insufficient. In addition, reaction temperature means the temperature of the gas in a chamber.

When introducing the mixed gas, a compound gas containing oxygen atoms or other gas other than fluorine gas may be first introduced into the chamber, and then fluorine gas may be introduced, or a premixed gas may be introduced. Good.

The contact time (treatment time) between the base particles and the mixed gas is not particularly limited, and the treatment may be performed until a desired degree of hydrophilicity is achieved, but the treatment is completed in about 10 to 60 minutes. After the treatment, it is preferable to perform a step of reducing the pressure again to about 0.13 Pa (0.001 Torr) and then introducing nitrogen gas. When this step is completed, the pressure is released to atmospheric pressure.

In the method for producing hydrophilized fine particles of the present invention, it is preferable that after the contact treatment with the mixed gas, the particles after contact with the mixed gas are further brought into contact with moisture. The —C (F) ═O formed on the particle surface by contact with the mixed gas is more efficiently converted to a carboxyl group by contacting with moisture. Further, HF generated at this time and HF or F ₂ adsorbed on the particle surface can be effectively removed. The moisture is preferably an alkaline aqueous solution and / or water and / or water vapor.

The mode in which the particles after contact with the mixed gas are brought into contact with water is any of the mode in which an alkaline aqueous solution is used as the water; the mode in which water and / or water vapor is used; May be. Among these, an embodiment using an alkaline aqueous solution and water and / or water vapor is preferable. The order of contact is not particularly limited, but from the viewpoint of efficiently removing HF or F ₂ adsorbed on the particle surface, the particle is brought into contact with an alkaline aqueous solution and then brought into contact with water and / or water vapor. Is desirable. When contacted with an alkaline aqueous solution, an alkali metal salt or amine salt of a carboxylic acid (hereinafter sometimes referred to as a carboxylate salt) is formed on the particle surface. This carboxylate is preferable because it further increases the hydrophilicity of the particles, and then the excess alkaline aqueous solution can be washed by contacting the particles with water and / or water vapor. In the present specification, hereinafter, the case of bringing particles into contact with an alkaline aqueous solution may be referred to as alkali treatment, and the case of bringing particles into contact with water may be referred to as warm water cleaning.

As a method of contact treatment with moisture to efficiently promote conversion to a carboxyl group or carboxylate, effectively remove HF and F ₂ adsorbed on the particle surface, and reduce eluting fluorine Although not particularly limited, for example, a method in which the chamber used for contact with the gas is opened to atmospheric pressure, and then water vapor is fed into the chamber to bring the particles into contact with water; After releasing to atmospheric pressure, water vapor is sent into the chamber to bring the particles into contact with water, and then the particles are taken out, dispersed in water and washed with a solvent containing water or water; after contact with the gas , A method in which particles taken out from the chamber are separately immersed in a water vapor atmosphere or washed with water or a solvent containing water; after contact with gas, the particles taken out from the chamber are placed in an alkaline aqueous solution. Method of dispersing and alkali treatment: After contact with gas, particles removed from the chamber are dispersed in an alkaline aqueous solution and alkali treated, and then the particles are taken out and dispersed in water with a solvent containing water or water. The method of washing | cleaning etc. are mentioned. The contact time with moisture is preferably about 1 to 600 minutes.

In order to efficiently convert —C (F) ═O to a carboxyl group or a carboxylate salt, and to effectively remove HF or F ₂ adsorbed on the particle surface, The temperature of (alkaline aqueous solution and / or water and / or water vapor) is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, still more preferably 60 ° C. or higher, and most preferably 80 ° C. or higher.

Further, when the particles are treated and washed with an alkaline aqueous solution or water or a solvent containing water, the particle concentration is preferably 0.5 to 50% by mass in a total of 100% by mass of the solvent and the particles. If the particle concentration is less than 0.5% by mass, the amount of fluorine-containing wastewater generated when washing a predetermined amount of particles increases, which may increase the cost industrially. If the particle concentration exceeds 50% by mass, cleaning may be insufficient. In order to efficiently clean the particles, it is also preferable to perform ultrasonic dispersion with the particles in a solvent.

As mentioned above, eluent fluorine such as fluorine components adhering to the particle surface may cause problems such as corrosion due to the safety of the particle or contact with other materials, so remove it as much as possible. When the alkali treatment using an alkaline aqueous solution as the moisture is performed, the leachable fluorine adsorbed on the particle surface can be more efficiently removed.

Examples of alkaline aqueous solutions include aqueous solutions of water-soluble amines such as ammonia, monoethanolamine, and diethanolamine, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide, and lithium carbonate. An aqueous solution containing an alkali metal ion in which an alkali metal compound such as an alkali metal carbonate such as sodium carbonate, potassium carbonate, rubidium carbonate or cesium carbonate is dissolved in water is preferably used. Among the above alkaline aqueous solutions, aqueous solutions containing alkali metal ions are preferable, those containing sodium are more preferable, and sodium hydroxide aqueous solutions are particularly preferable.

The concentration of the alkaline aqueous solution is preferably 0.01N to 5N. More preferably, it is 0.05N to 2N, and still more preferably 0.1N to 1N. The specific method of the alkali treatment is not particularly limited. For example, after contact with a gas, particles taken out from the chamber are dispersed in an alkaline aqueous solution having the above concentration, and then at a temperature of 80 ° C. or higher for 1 minute to 600 minutes. And a method of bringing the particles into contact with an alkaline aqueous solution.

The amount of fluorine atoms contained in the resulting hydrophilized fine particles (total fluorine amount), the amount of fluorine atoms ionized and liberated (elutable fluorine content), and the fluorine atoms that are incorporated into the particle skeleton by chemical bonding and are not liberated The amount (non-eluting fluorine content) can be measured by the following method.

[Total fluorine content: oxygen combustion flask method]
2 mg of particles are weighed on a 3 cm × 2 cm filter paper and wrapped so that the particles do not scatter. The platinum basket attached to the oxygen flask is heated with a Bunsen burner and kept in a red hot state for about 5 seconds. When the basket cools, pack the filter paper wrapped in particles into the basket. When 15 ml of distilled water is put into a 500 ml oxygen flask and the inner wall of the flask is wetted, the inside of the flask is replaced with an oxygen atmosphere. Light the filter paper in the basket and quickly insert it into the flask. After combustion, the flask is shaken a few times and allowed to stand for 30 minutes, after which the contents of the flask are transferred to a polypropylene beaker with a capacity of 100 ml, and further distilled water is added to adjust the total volume to 50 ml. The pH was adjusted to a constant level by adding 5 ml of a buffer solution, and the fluorine ion concentration was measured with an ion meter while stirring with a magnetic stirrer to determine the total fluorine amount (mg / g). Here, “Orion1115000 4-Star” (manufactured by Thermo Fisher Scientific) was used as the ion meter, and “Orion 9609BNWP” (manufactured by the same company) was used as the electrode.

[Elutable fluorine content: Fluorine ion electrode method]
50 ml of distilled water was put into a 100 ml polypropylene beaker, and 5 ml of buffer solution was further added. While stirring with a magnetic stirrer, the fluorine ion electrode was immersed in the liquid. 0.2 g of particles were added, and the fluorine ion concentration was measured for 360 minutes after the addition, and the elution fluorine content (mg / g) was obtained. The same ion meter and electrode as those used in the measurement of the total fluorine amount were used.

[Non-eluting fluorine content]
The non-eluting fluorine content (mg / g) was determined by the following formula.
Non-eluting fluorine content = (total fluorine content)-(eluting fluorine content)

In addition, the presence or absence of the generation of carboxyl groups on the particle surface after the hydrophilization treatment is determined by an X-ray photoelectron analyzer (ESCA: for example, a scanning X-ray photoelectron analyzer “PHIPQuanteraMSXM (registered trademark)” manufactured by ULVAC-PHI). Can be measured. In the present invention, the determination was made based on the presence or absence of a peak at 288 eV.

Next, the base particles will be described. The substrate particles used in the method of the present invention are not particularly limited as long as they are particles containing a vinyl polymer, and particles made of only a vinyl polymer, or an organic / inorganic composite made of a material in which an organic material and an inorganic material are combined. Any of the particles can be used. The vinyl of the present invention includes (meth) acryloyl. Specific examples of the vinyl polymer fine particles include particles composed only of vinyl polymers such as (meth) acrylic (co) polymers, (meth) acrylic-styrene copolymers, and polymerizable ( Meaning of containing vinyl group; the same applies hereinafter) Organic radical composite particles and / or condensation polymers of alkoxysilane, and organic-inorganic composite particles such as a copolymer of polymerizable alkoxysilane and vinyl monomer. In the following description, the term “vinyl polymer” means an organic-only polymer obtained by polymerizing vinyl monomers. The “vinyl polymer fine particles” as used in the present invention means particles containing a component or a skeleton made of “vinyl polymer”. Although details of the production method of these vinyl polymer fine particles will be described later, emulsion polymerization, suspension polymerization, seed polymerization, sol-gel method, etc. can be adopted, among which seed polymerization or sol-gel method can reduce the particle size distribution. Therefore, it is preferable. The composition of the fine particles can be confirmed by GC-MS or the like.

[Vinyl polymer particles]
Vinyl polymer particles are obtained by polymerizing a monomer composition containing a monomer mixture containing a vinyl monomer. The vinyl monomer contained in the monomer mixture is a non-crosslinkable monomer having one vinyl group in one molecule, and a crosslinkable monomer having two or more vinyl groups in one molecule. Any of these can be used.

Examples of the non-crosslinkable monomer include (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, glycidyl (meth) acrylate, cyclohex (Meth) acrylates such as xyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, -(Meth) acrylic monomers such as hydroxyalkyl (meth) acrylates such as hydroxybutyl (meth) acrylate: styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylvinylbenzene, α- Styrene monomers such as methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, parahydroxystyrene, etc .: 2-hydroxyethyl Hydroxyl group-containing vinyl ethers such as vinyl ether and 4-hydroxybutyl vinyl ether: hydroxyl group-containing allyl ethers such as 2-hydroxyethyl allyl ether and 4-hydroxybutyl allyl ether. In addition, when (meth) acrylic acid is used as the non-crosslinkable monomer, it may be partially neutralized with an alkali metal. These non-crosslinkable monomers may be used alone or in combination of two or more. Among these non-crosslinkable monomers, a monomer having no ester bond in the molecule is preferably used as an essential component, and among them, a styrene monomer is preferable, and styrene, α-methylstyrene are particularly preferable. Ethyl vinyl benzene and the like are preferable.

Examples of the crosslinkable monomer include trimethylolpropane triacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, decaethylene glycol dimethacrylate, pentadecaethylene glycol dimethacrylate, pentacontact ethylene glycol dimethacrylate. Methacrylate, 1,3-butylene dimethacrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, allyl methacrylate, tri Multifunctional (meth) acrylates such as methylolpropane trimethacrylate and pentaerythritol tetraacrylate; polyethylene glycol di (meth) Polyalkylene glycol di (meth) acrylates such as acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate; aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; N, Examples thereof include cross-linking agents such as N-divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfonic acid; polybutadiene, polyisoprene unsaturated polyester, and the like. These crosslinkable monomers may be used alone or in combination of two or more. Among these, it is preferable to use a monomer having no ester bond in the molecule as an essential component. Among them, an aromatic divinyl compound is preferable, and divinylbenzene is particularly preferable.

When a styrene monomer is used as the non-crosslinkable monomer and an aromatic divinyl compound is used as the crosslinkable monomer, it is preferable because the effect of making the particles hydrophilic by the method of the present invention is easily obtained.

The content of the crosslinkable monomer in the monomer mixture is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and 50% by mass or less. More preferably, it is 40 mass% or less, More preferably, it is 30 mass% or less. By setting the content of the crosslinkable monomer in the monomer mixture to 1% by mass or more, the solvent resistance and heat resistance of the vinyl polymer particles are increased, and the content of the crosslinkable monomer is set to 50%. By setting the mass% or less, the hardness of the particles can be made appropriate.

Further, when the monomer composition is polymerized, a polymerization initiator or a dispersion stabilizer may be used as necessary. As the polymerization initiator, any of those usually used for polymerization can be used. For example, a peroxide initiator, an azo initiator, or the like can be used. Examples of the peroxide initiator include hydrogen peroxide, peracetic acid, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide. Oxide, t-butylperoxy-2-ethylhexanoate, di-t-butylperoxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, methyl ethyl ketone peroxide, diisopropyl Examples thereof include peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, and the like.

Examples of the azo initiator include dimethyl 2,2-azobisisobutyronitrile, azobiscyclohexacarbonitrile, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl). Valeronitrile), 2,2′-azobis (2,3-dimethylbutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,3,3-trimethyl) Butyronitrile), 2,2′-azobis (2-isopropylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (4-methoxy-2,4- Dimethylvaleronitrile), 2- (carbamoylazo) isobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 4,4′-azobis (4-cyano) Pentane acid), 4,4'-azobis (4-cyanovaleric acid), dimethyl-2,2'-azobis isobutyrate, and the like.

These polymerization initiators may be used alone or in combination of two or more. The addition amount of these polymerization initiators is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and 5 parts by mass or less with respect to 100 parts by mass of the monomer mixture. It is preferable that it is 3 parts by mass or less.

The dispersion stabilizer is used to stabilize the droplet diameter of the monomer composition during the polymerization reaction when the monomer composition is polymerized using a suspension polymerization method or the like. The dispersion stabilizer may be dissolved or dispersed in a solvent (for example, an aqueous solvent) as a dispersion medium without being contained in the monomer composition. As the dispersion stabilizer, any of an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant may be used. A dispersion stabilizer may be used independently and may use 2 or more types together. Among these, fatty acid oils such as sodium oleate and castor oil potassium; alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; polyoxyethylene distyryl phenyl ether sulfate ammonium salt, polyoxyethylene distyryl phenyl ether sulfate Polyoxyethylene distyryl phenyl ether sulfate such as sodium salt; alkylbenzene sulfonate such as sodium dodecylbenzene sulfonate; alkyl naphthalene sulfonate, alkane sulfonate, dialkyl sulfosuccinate, alkyl phosphate ester, naphthalene Anion such as sulfonic acid formalin condensate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl sulfate Emissions surfactants are preferred.

The amount of the dispersion stabilizer may be appropriately adjusted according to the desired size of the vinyl polymer particles. For example, if it is desired to obtain vinyl polymer particles having an average particle diameter of 3 μm or more and 30 μm or less, the addition amount of the dispersion stabilizer may be 0.1 parts by mass or more with respect to 100 parts by mass of the monomer mixture. Preferably, it is 0.5 parts by mass or more, more preferably 1 part by mass or more, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 3 parts by mass or less.

In addition, pigments, plasticizers, polymerization stabilizers, fluorescent brighteners, magnetic powders, ultraviolet absorbers, antistatic agents, flame retardants, and the like may be added to the monomer composition. The amount of these additives used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and still more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the monomer mixture. It is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 3 parts by mass or less.

[Method for producing vinyl polymer particles]
In the method for producing vinyl polymer particles, a monomer composition containing the monomer mixture as described above is polymerized. In addition, as a polymerization method, well-known polymerization methods, such as suspension polymerization, seed polymerization, and emulsion polymerization, can be employ | adopted, Among these, suspension polymerization and seed polymerization are preferable.

When the suspension polymerization method is employed, the solvent used is not particularly limited as long as it does not completely dissolve the monomer composition, but an aqueous medium is preferably used. These solvents can be appropriately used within a range of usually 20 parts by mass or more and 10,000 parts by mass or less with respect to 100 parts by mass of the monomer composition. As a method for producing vinyl polymer particles, a method in which a monomer composition containing a monomer mixture and a polymerization initiator is suspended and polymerized in an aqueous solvent in which a dispersion stabilizer is dissolved or dispersed is preferable. It is.

The polymerization temperature of the suspension polymerization is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, further preferably 60 ° C. or higher, preferably 95 ° C. or lower, more preferably 90 ° C. or lower, still more preferably. Is 85 ° C. or lower. The polymerization reaction time is preferably 1 hour or longer, more preferably 2 hours or longer, further preferably 3 hours or longer, preferably 10 hours or shorter, more preferably 8 hours or shorter, still more preferably. 5 hours or less. In order to control the particle diameter of the vinyl polymer to be produced, the polymerization reaction is preferably performed after regulating the droplet diameter of the monomer composition or while regulating the droplet diameter. The regulation of the droplet diameter of the monomer composition is, for example, that a suspension in which the monomer composition is dispersed in an aqueous medium is changed to T.P. K. It can be carried out by stirring with a high-speed stirrer such as a homomixer or a line mixer. The vinyl polymer particles produced by the polymerization reaction may be dried and further subjected to a classification process or the like if necessary. In addition, it is preferable to perform drying at 150 degrees C or less, More preferably, it is 120 degrees C or less, More preferably, it is 100 degrees C or less.

When employing the seed polymerization method, it is preferable to use a styrene-based or (meth) acrylate-based polymer as the seed particle, and it is more preferable to use a non-crosslinked type or a fine particle having a low degree of crosslinking. The average particle diameter of the seed particles is preferably 0.1 μm to 10 μm, and the value (CV value) represented by 100 × particle diameter standard deviation / average particle diameter is preferably 10 or less. As a method for producing such seed particles, a conventionally used method can be employed, and examples thereof include soap-free emulsion polymerization and dispersion polymerization.

The charged amount of the monomer composition in the seed polymerization is preferably 0.5 to 50 parts by mass with respect to 1 part by mass of the seed particles. If the charged amount of the monomer composition is too small, the increase in the particle size due to polymerization is small, and if it is too large, the monomer composition is not completely absorbed by the seed particles and polymerizes independently in the medium. May produce abnormal particles. In addition, about the polymerization temperature and the drying conditions of the obtained particle | grains, the conditions similar to the said suspension polymerization are applicable.

[Organic inorganic composite particles]
Organic-inorganic composite particles are particles comprising an organic part derived from a vinyl polymer and an inorganic part. As an aspect of the organic-inorganic composite particles, an aspect in which inorganic fine particles such as metal oxides such as silica, alumina and titania, metal nitrides, metal sulfides and metal carbides are dispersed and contained in the vinyl polymer; Organo) A mode in which a metalloxane chain (molecular chain containing a “metal-oxygen-metal” bond) such as polysiloxane and polytitanoxane and an organic molecule are combined at the molecular level; a vinyl polymer such as vinyltrimethoxysilane is formed. Polymeric unit having a vinyl group and polysiloxane using particles obtained by causing an organoalkoxysilane having a vinyl group to undergo a hydrolysis condensation reaction or a polymerization reaction of a vinyl group or a silane compound having a hydrolyzable silyl group. Organic-inorganic composite containing vinyl polymer skeleton and polysiloxane skeleton, such as particles obtained by reacting with polymer Aspects such as made of the child and the like. Among these, an embodiment composed of organic-inorganic composite particles including a vinyl polymer skeleton and a polysiloxane skeleton is particularly preferable.

Hereinafter, organic-inorganic composite particles containing a vinyl polymer skeleton and a polysiloxane skeleton (hereinafter sometimes simply referred to as “composite particles”) will be described in detail.

The vinyl polymer skeleton is a vinyl polymer having a main chain composed of a repeating unit represented by the following formula (1), having a side chain, having a branched structure, and further having a crosslinked structure. It may be a thing. The hardness of the composite particles can be controlled appropriately.

Further, the polysiloxane skeleton is defined as a portion in which a siloxane unit represented by the following formula (2) is continuously chemically bonded to form a network of a network structure.

The amount of SiO ₂ constituting the polysiloxane skeleton is preferably 0.1% by mass or more, more preferably 1% by mass or more, and preferably 25% by mass or less with respect to the mass of the composite particles. More preferably, it is 10 mass% or less. When the amount of SiO ₂ in the polysiloxane skeleton is in the above range, the hardness of the composite particles can be easily controlled. The amount of SiO ₂ constituting the polysiloxane skeleton is a mass percentage obtained by measuring the mass before and after firing the particles at a temperature of 800 ° C. or higher in an oxidizing atmosphere such as air.

The composite particles can be arbitrarily adjusted by appropriately changing the ratio of the polysiloxane skeleton part and the vinyl polymer skeleton part with respect to each of the mechanical properties such as hardness and breaking strength. The polysiloxane skeleton in the composite particles is preferably obtained by hydrolytic condensation reaction of a silane compound having a hydrolyzable group.

Although it does not specifically limit as a silane compound which has hydrolyzability, For example, the silane compound represented by following General formula (3), its derivative (s), etc. are mentioned.
R ' _m SiX _4-m (3)
(In the formula, R ′ may have a substituent and represents at least one group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group and an unsaturated aliphatic group, and X represents a hydroxyl group, an alkoxy group. And represents at least one group selected from the group consisting of a group and an acyloxy group, and m is an integer from 0 to 3.)

Although it does not specifically limit as a silane compound represented by General formula (3), For example, as m = 0, tetrafunctional silane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, etc. Silanes having m = 1 are methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, phenyltrimethoxysilane, benzyltrimethoxysilane Naphthyltrimethoxysilane, methyltriacetoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, 3- (meth) acryloxypropi Trifunctional silanes such as trimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane; those with m = 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, diacetoxydimethylsilane, diphenylsilanediol, etc. Examples of bifunctional silanes: m = 3 include monofunctional silanes such as trimethylmethoxysilane, trimethylethoxysilane, and trimethylsilanol.

The derivative of the silane compound represented by the general formula (3) is not particularly limited. For example, a part of X is substituted with a group capable of forming a chelate compound such as a carboxyl group and a β-dicarbonyl group. Examples thereof include compounds and low condensates obtained by partially hydrolyzing the silane compound.

The hydrolyzable silane compound may be used alone or in combination of two or more. In addition, in the general formula (3), when only the silane compound in which m = 3 and its derivative are used as raw materials, composite particles cannot be obtained.

When the polysiloxane skeleton of the composite particle has an organosilicon atom in which a silicon atom is directly bonded to at least one carbon atom in the vinyl polymer skeleton, the hydrolyzable silane compound It is necessary to use those having an organic group containing a vinyl bond.

Examples of the organic group containing a vinyl bond include organic groups represented by the following general formulas (4), (5), and (6).
CH ₂ = C (-R ^a ) -COOR ^b- (4)
(In the formula, R ^a represents a hydrogen atom or a methyl group, and R ^b represents a divalent organic group having 1 to 20 carbon atoms which may have a substituent.)
CH ₂ = C (-R ^c )-(5)
(In the formula, R ^c represents a hydrogen atom or a methyl group.)
CH ₂ = C (-R ^d ) -R ^e- (6)
(In the formula, R ^d represents a hydrogen atom or a methyl group, and R ^e represents a divalent organic group having 1 to 20 carbon atoms which may have a substituent.)

Examples of the organic group of the general formula (4) include a (meth) acryloxy group, and the silane compound of the general formula (3) having a (meth) acryloxy group includes, for example, γ-methacryloxypropyltrimethoxy. Silane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltriacetoxysilane, γ-methacryloxyethoxypropyltrimethoxysilane (or γ-trimethoxysilylpropyl-β-methacryloxyethyl ether), γ- (methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropylmethyldimethoxysilane, etc. These may be used alone or in combination of two or more.

Examples of the organic group of the general formula (5) include a vinyl group and an isopropenyl group. Examples of the silane compound of the general formula (3) having these organic groups include vinyl trimethoxysilane, Examples include vinyltriethoxysilane, vinyltriacetoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, and vinylmethyldiacetoxysilane. These may be used alone or in combination of two or more.

Examples of the organic group of the general formula (6) include 1-alkenyl group or vinylphenyl group, isoalkenyl group or isopropenylphenyl group, and the silane of the general formula (3) having these organic groups. Examples of the compound include 1-hexenyltrimethoxysilane, 1-hexenyltriethoxysilane, 1-octenyltrimethoxysilane, 1-decenyltrimethoxysilane, γ-trimethoxysilylpropyl vinyl ether, ω-trimethoxysilylundecane. Examples include acid vinyl ester, p-trimethoxysilylstyrene, 1-hexenylmethyldimethoxysilane, 1-hexenylmethyldiethoxysilane, and the like. These may be used alone or in combination of two or more.

The vinyl polymer skeleton contained in the composite particles is obtained by allowing the particles having a polysiloxane skeleton obtained by the hydrolysis-condensation reaction of (I) silane compound to absorb the vinyl monomer component and then polymerizing the particles. be able to. In particular, when the silane compound has an organic group containing a vinyl bond together with a hydrolyzable group, it can also be obtained by polymerizing this after the hydrolysis condensation reaction of the (II) silane compound.

The composite particle has (i) a form in which the polysiloxane skeleton has an organosilicon atom in which a silicon atom is directly chemically bonded to at least one carbon atom in the vinyl polymer skeleton (chemical bond type). (Ii) The form (IPN type) does not have such an organosilicon atom in the molecule, and is not particularly limited, but the form (i) is preferred. In addition, when the vinyl polymer skeleton is obtained together with the polysiloxane skeleton by the method (I), composite particles having the form (ii) are obtained. In particular, the silane compound has a vinyl bond together with a hydrolyzable group. If it has an organic group containing, composite particles having both the forms (i) and (ii) can be obtained. Further, when the vinyl polymer skeleton is obtained together with the polysiloxane skeleton as in (II), composite particles having the form (i) are obtained.

In the methods (I) and (II), examples of the monomer that can be absorbed by the particles having a polysiloxane skeleton include the vinyl monomers described above, and depending on the desired physical properties of the composite particles. It can be selected appropriately. These may be used alone or in combination of two or more.

For example, a hydrophobic vinyl-based monomer is preferable because a stable emulsion in which the monomer component is emulsified and dispersed can be generated when the monomer component is absorbed into particles having a polysiloxane skeleton. Moreover, if the crosslinkable monomer described above is used, the mechanical properties of the resulting composite particles can be easily adjusted, and the solvent resistance of the composite particles can be improved. As the crosslinkable monomer, those exemplified as those used for the vinyl polymer particles can be used.

The method for producing composite particles preferably includes a hydrolysis-condensation step and a polymerization step, and more preferably includes an absorption step for absorbing the polymerizable monomer after the hydrolysis and condensation step and before the polymerization step. . By including the absorption step, the content of the vinyl polymer skeleton component in the composite particles and the refractive index of the vinyl polymer skeleton contained can be adjusted. In addition, when the silane compound used in the hydrolysis-condensation step does not have an element that constitutes a vinyl polymer skeleton together with an element that can constitute a polysiloxane skeleton structure, the absorption step is essential, and this absorption step is followed. A vinyl polymer skeleton is formed in the polymerization process.

The hydrolysis-condensation step is a step of performing a reaction in which a silane compound is hydrolyzed in a solvent containing water to undergo condensation polymerization. By the hydrolysis condensation step, particles having a polysiloxane skeleton (polysiloxane particles) can be obtained. Hydrolysis and polycondensation can employ any method such as batch, split, and continuous. In the hydrolysis and condensation polymerization, basic catalysts such as ammonia, urea, ethanolamine, tetramethylammonium hydroxide, alkali metal hydroxide, and alkaline earth metal hydroxide can be preferably used as the catalyst.

In the solvent containing water, an organic solvent can be contained in addition to water and the catalyst. Examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1,4-butanediol; acetone, Examples thereof include ketones such as methyl ethyl ketone; esters such as ethyl acetate; (cyclo) paraffins such as isooctane and cyclohexane; aromatic hydrocarbons such as benzene and toluene. These may be used alone or in combination of two or more.

In the hydrolysis-condensation step, anionic, cationic and nonionic surfactants and polymer dispersants such as polyvinyl alcohol and polyvinylpyrrolidone can be used in combination. These may be used alone or in combination of two or more.

Hydrolytic condensation is performed by mixing the silane compound as a raw material with a solvent containing a catalyst, water, and an organic solvent, and then at a temperature of 0 ° C. to 100 ° C., preferably 0 ° C. to 70 ° C., for 30 minutes to 100 hours. It can carry out by stirring below. Thereby, polysiloxane particles are obtained. Moreover, after producing a particle by performing a hydrolysis-condensation reaction to a desired degree, this may be used as a seed particle, and a silane compound may be further added to the reaction system to grow the seed particle.

The absorption process is not particularly limited as long as it proceeds in the presence of the monomer component in the presence of the polysiloxane particles. Therefore, the monomer component may be added to the solvent in which the polysiloxane particles are dispersed, or the polysiloxane particles may be added to the solvent containing the monomer component. Especially, it is preferable to add a monomer component in the solvent which disperse | distributed polysiloxane particle | grains previously like the former. In particular, the method of adding the monomer component to the reaction liquid without taking out the polysiloxane particles obtained in the hydrolysis and condensation process from the reaction liquid (polysiloxane particle dispersion) does not complicate the process. It is preferable because of its excellent properties.

In the absorption step, the monomer component is absorbed in the structure of the polysiloxane particle, but the concentration of each of the polysiloxane particle and the monomer component is increased so that the absorption of the monomer component proceeds quickly, It is preferable that the mixing ratio of the polysiloxane and the monomer component, the processing method and means for mixing, the temperature and time at the time of mixing, the processing method and means after mixing, etc. are appropriately set and performed under the conditions.

These requirements may be appropriately determined depending on the type of polysiloxane particles and monomer components used. These conditions may be applied singly or in combination of two or more.

In the absorption step, the amount of the monomer component added is preferably 0.01 to 100 times by mass with respect to the mass of the silane compound used as the raw material for the polysiloxane particles. More preferably, they are 0.5 times or more and 30 times or less, More preferably, they are 1 time or more and 20 times or less. If the amount added is less than the above range, the amount of monomer component absorption of the polysiloxane particles is reduced, the mechanical properties of the resulting composite particles may be insufficient, if exceeding the above range, There is a tendency that it is difficult to completely absorb the added monomer component in the polysiloxane particles, and the unabsorbed monomer component remains, and thus aggregation between particles is likely to occur in the subsequent polymerization stage. There is.

In the absorption step, the timing of addition of the monomer component is not particularly limited, and may be added all at once, may be added in several times, or may be fed at an arbitrary rate. In addition, when adding the monomer component, either the monomer component alone or the solution of the monomer component may be added, but the monomer component is previously added to water or an aqueous medium with an emulsifier. It is preferable to mix the emulsified and emulsified liquid into the polysiloxane particles because the polysiloxane particles can be more efficiently absorbed.

The emulsifier is not particularly limited. For example, the anionic surfactants exemplified as the dispersion stabilizer, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan Dispersion of polysiloxane particles and composite particles after nonionic surfactants such as fatty acid esters, polyoxyethylene alkylamines, glycerin fatty acid esters, oxyethylene-oxypropylene block polymers have absorbed the polysiloxane particles and monomer components This is preferable because the state can be stabilized. These emulsifiers may be used alone or in combination of two or more.

The amount of the emulsifier used is not particularly limited, and specifically, it is preferably 0.01 parts by mass or more, more preferably 0 with respect to 100 parts by mass of the total mass of the monomer components to be emulsified. 0.05 parts by mass or more, more preferably 1 part by mass or more, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 5 parts by mass or less. When the amount is less than 0.01 parts by mass, a stable emulsion may not be obtained. When the amount exceeds 10 parts by mass, emulsion polymerization or the like may occur as a side reaction. In order to obtain an emulsified liquid, the monomer component may be made into an emulsion state in water using a homomixer or an ultrasonic homogenizer together with the emulsifier.

Further, when emulsifying and dispersing the monomer component with an emulsifier, it is preferable to use water or a water-soluble organic solvent that is 0.3 to 10 times the mass of the monomer component. Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1,4-butanediol; acetone And ketones such as methyl ethyl ketone; esters such as ethyl acetate;

The absorption step is preferably performed in the temperature range of 0 ° C. to 60 ° C. with stirring for 5 minutes to 720 minutes. These conditions may be set as appropriate depending on the type of polysiloxane particles and monomers to be used, and these conditions may be used alone or in combination of two or more.

In the absorption process, for determining whether the monomer component has been absorbed by the polysiloxane particles, for example, before adding the monomer component and after the absorption step, observe the particles with a microscope to absorb the monomer component. Thus, it can be easily determined by confirming that the particle size is increased.

The polymerization step is a step of obtaining particles having a vinyl polymer skeleton by polymerizing a monomer component. Specifically, when a silane compound having an organic group having a vinyl bond is used, it is a step of polymerizing the vinyl bond of the organic group to form a vinyl polymer skeleton. Is a process of polymerizing the absorbed monomer component, or the absorbed monomer component and the vinyl bond of the polysiloxane skeleton to form a vinyl (system) polymer skeleton, if both fall under Can be a step of forming a vinyl (system) polymer skeleton by either reaction.

The polymerization reaction may be performed in the middle of the hydrolysis-condensation step or the absorption step, and may be performed after one or both of the steps, and is not particularly limited, but usually after the hydrolysis-condensation step (the absorption step). If done, of course, start after the absorption step).

The polymerization method is not particularly limited, and for example, any of a method using a radical polymerization initiator, a method of irradiating ultraviolet rays or radiation, a method of applying heat, and the like can be adopted. Although it does not specifically limit as said radical polymerization initiator, For example, what is used for superposition | polymerization of the said vinyl polymer particle can be mentioned. These radical polymerization initiators may be used alone or in combination of two or more.

The amount of the radical polymerization initiator used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and still more preferably 0.001 part by mass with respect to 100 parts by mass of the total mass of the monomer components. It is 1 part by mass or more, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 5 parts by mass or less. When the usage-amount of a radical polymerization initiator is less than 0.001 mass part, the polymerization degree of a monomer component may not rise. The method of charging the radical polymerization initiator into the solvent is not particularly limited, and is a method in which the entire amount is initially charged (before the reaction is started) (the mode in which the radical polymerization initiator is emulsified and dispersed together with the monomer component, A mode in which a radical polymerization initiator is charged after absorption); a method in which a part is charged first, and the rest is continuously fed, or intermittently pulsed, or a combination of these, etc. Any known method can be employed.

The reaction temperature for carrying out radical polymerization is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, preferably 100 ° C. or lower, more preferably 80 ° C. or lower. If the reaction temperature is too low, the degree of polymerization does not increase sufficiently and the mechanical properties of the composite particles tend to be insufficient. On the other hand, if the reaction temperature is too high, aggregation between particles occurs during the polymerization. It tends to happen easily. The reaction time for performing radical polymerization may be appropriately changed according to the type of polymerization initiator to be used, but is usually preferably 5 minutes or more, more preferably 10 minutes or more, and preferably 600 minutes or less. More preferably, it is 300 minutes or less. When the reaction time is too short, the degree of polymerization may not be sufficiently increased, and when the reaction time is too long, aggregation tends to occur between particles.

According to the above-mentioned production method, base particles composed of vinyl polymer fine particles having desirable characteristics (such as mechanical characteristics and particle size distribution characteristics) described later can be obtained.

The shape of the base particle used in the present invention is not particularly limited, and may be any of spherical, spheroid, scallop, thin plate, needle, eyebrows, and the particle surface has a smooth shape. The shape may be any of a shape, a bowl shape and a porous shape. Among them, the spherical shape is preferable because it has many industrial uses. The magnitude | size of a base particle shall be 1 mm (1000 micrometers) or less by a mass mean particle diameter. This is because particles exceeding 1 mm have limited applications and few industrial fields of use. The mass average particle diameter is preferably 0.05 to 500 μm, more preferably 0.1 to 100 μm, and further preferably 0.5 to 30 μm. The mass average particle size means a value obtained as a volume average particle size in a conventionally known particle size distribution measurement method, and specifically, a precise particle size distribution measurement apparatus (for example, trade name “Coulter Multi” using the Coulter principle). It is a value measured by “Sizer III” manufactured by Beckman Coulter, Inc.

Further, the coefficient of variation (CV value) in the particle diameter of the substrate particles used in the present invention is preferably 40% or less. If the CV value exceeds 40%, the particle size variation is too large, and there is a risk of unevenness in the hydrophilic treatment. The CV value is a value obtained by applying the mass average particle diameter of the base material particle measured by a precision particle size distribution measuring apparatus using the Coulter principle and the standard deviation of the particle diameter of the base material particle to the following formula. is there.
Coefficient of variation (%) of substrate particles = 100 × standard deviation of particle diameter / mass average particle diameter

The preferred range of the mass average particle diameter and coefficient of variation of the hydrophilized fine particles is the same as that of the base particles.

The base particles are hydrophilized by the method described above. The dispersibility, mechanical characteristics, hue, and particle size distribution characteristics (CV value) of the base particles and the hydrophilized fine particles are preferably approximately the same, and preferably not changed before and after the hydrophilization treatment. The dispersibility is a property that the particles are not fixed or fused.

The mechanical characteristics can be evaluated by, for example, a compression elastic modulus, a compression fracture load, a recovery rate, and the like. The compression elastic modulus of the present invention is the elastic modulus (N / mm ² : MPa) when a particle is loaded and deformed by 10%, and the compressive fracture load is the load (mN) when compression is strengthened to cause fracture. The recovery rate is the recovery rate after compression (%). These measurement methods will be described in detail in Examples. Substrate particles, in any of the hydrophilic fine particles, the compression modulus is preferably 1000 N / mm ² or more, more preferably 2000N / mm ² or more, 3000N / mm ² or more is more preferable. Similarly, the compressive breaking load is preferably 1 mN or more, more preferably 3 mN or more, and further preferably 5 mN or more. Further, the recovery rate is preferably 0.5% or more, more preferably 1% or more, and further preferably 5% or more.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited by the following Example, As long as it changes and implements in the range which does not deviate from the meaning of this invention, it is contained in the scope of the present invention. In the following, “part” means “part by mass” and “%” means “% by mass” unless otherwise specified.

Synthesis example 1
In a four-necked flask equipped with a condenser, a thermometer, and a dripping port, 400 parts of ion-exchanged water, 6 parts of 25% aqueous ammonia and 180 parts of methanol are placed, and this solution is stirred with 3-methacryloxypropyltrimethoxy. 100 parts of silane was added from the dropping port, and a hydrolytic condensation reaction of 3-methacryloxypropyltrimethoxysilane was performed to obtain an emulsion of polysiloxane particles.

Subsequently, 0.35 part of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd .: “Hytenol (registered trademark) NF-08”) as an emulsifier was dissolved in 175 parts of ion-exchanged water. A solution in which 70 parts of divinylbenzene and 3.4 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd .: “V-65”) are added is added to a TK homomixer ( The emulsion of the monomer component was prepared by emulsifying and dispersing at 6000 rpm for 5 minutes using a special machine chemical industry).

The obtained emulsion was added to an emulsion of polysiloxane particles and further stirred. Two hours after the addition of the emulsion, the reaction solution was sampled and observed with a microscope. As a result, it was confirmed that the polysiloxane particles were enlarged by absorbing the monomer component.

Next, the reaction solution was heated to 65 ° C. under a nitrogen atmosphere and held at 65 ° C. for 2 hours to perform radical polymerization of the monomer component. The emulsion after radical polymerization was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and methanol. The substrate particles 1 (organic inorganic composite particles) were obtained by vacuum drying at 80 ° C. for 12 hours. When the particle diameter of the substrate particle 1 was measured by Coulter Multisizer III type (manufactured by Beckman Coulter, Inc.), the mass average particle diameter was 3.8 μm, and the coefficient of variation (CV value) was 2.9%. The average particle size of the base particles was determined by measuring the particle size of 30000 particles using a Coulter Multisizer III type (manufactured by Beckman Coulter, Inc.). The CV value (%) of the particle diameter was determined according to the following formula.

Synthesis example 2
An emulsion of polysiloxane particles was prepared in the same manner as in Synthesis Example 1 except that the amount of 3-methacryloxypropyltrimethoxysilane added to the flask was 50 parts.

Next, from a solution obtained by dissolving 0.75 part of “Hytenol NF-08” in 175 parts of ion-exchanged water, from 125 parts of styrene, 25 parts of 1,6-hexanediol dimethacrylate and 4 parts of “V-65”. The resulting solution was added and emulsified and dispersed at 6000 rpm for 5 minutes using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare an emulsion of monomer components. Thereafter, in the same manner as in Synthesis Example 1, substrate particles 2 (organic / inorganic composite particles) were obtained.

Next, the reaction solution was heated to 65 ° C. under a nitrogen atmosphere and held at 65 ° C. for 2 hours to perform radical polymerization of the monomer component. The emulsion after radical polymerization was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and methanol. The substrate particles 2 were obtained by vacuum drying at 80 ° C. for 12 hours. The base material particle 2 had a mass average particle diameter of 3.8 μm and a CV value of 3.3%.

Synthesis example 3
Substrate particles in the same manner as in Synthesis Example 2, except that the amount of 25% aqueous ammonia was 20 parts, and 75 parts of styrene and 75 parts of 1,6-hexanedimethacrylate were used when preparing the emulsion of the monomer component. 3 (organic inorganic composite particles) was obtained. The base particle 3 had a mass average particle diameter of 2.1 μm and a CV value of 5.2%.

Synthesis example 4
Base material particles 4 (organic / inorganic composite particles) were obtained in the same manner as in Synthesis Example 1 except that the amount of 25% aqueous ammonia was 20 parts. The base particle 4 had a mass average particle diameter of 2.0 μm and a CV value of 5.3%.

Synthesis example 5
A four-necked flask equipped with a cooling tube, a thermometer, and a dropping port was charged with 150 parts of an ion exchange aqueous solution in which 2 parts of the above-mentioned “Hytenol NF-08” was dissolved as a dispersion stabilizer. 100 parts of divinylbenzene and 2 parts of “V-65” were added, and the mixture was emulsified and dispersed at 5000 rpm for 5 minutes with the TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a suspension.

To this suspension, 250 parts of ion-exchanged water was added, the temperature was raised to 65 ° C. under a nitrogen atmosphere, and the mixture was held at 65 ° C. for 2 hours to perform radical polymerization. The emulsion after radical polymerization was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and methanol, and further classified. Base particles 5 (vinyl polymer particles) were obtained by vacuum drying the classified particles at 80 ° C. for 12 hours. The base particle 5 had a mass average particle diameter of 2.1 μm and a CV value of 25.0%.

Synthesis Example 6
Substrate particles 6 (vinyl polymer particles) in the same manner as in Synthesis Example 5 except that a monomer mixture comprising 30 parts of styrene and 70 parts of 1,6-hexanediol dimethacrylate was used instead of 100 parts of divinylbenzene. ) The base particle 6 had a mass average particle diameter of 2.8 μm and a CV value of 19.0%.

Synthesis example 7
Substrate particles 7 (vinyl polymer particles) in the same manner as in Synthesis Example 5 except that a monomer mixture comprising 70 parts of styrene and 30 parts of 1,6-hexanediol dimethacrylate was used instead of 100 parts of divinylbenzene. ) The base particle 7 had a mass average particle diameter of 2.3 μm and a CV value of 23.5%.

Synthesis example 8
Substrate particles 8 (vinyl polymer particles) were obtained in the same manner as in Synthesis Example 5 except that a monomer mixture consisting of 70 parts of methyl methacrylate and 30 parts of ethylene glycol dimethacrylate was used instead of 100 parts of divinylbenzene. It was. The base particle 8 had a mass average particle diameter of 3.2 μm and a CV value of 30.0%.

Synthesis Example 9
Base material particles 9 (organic inorganic composite particles) were obtained in the same manner as in Synthesis Example 1 except that the amount of 25% aqueous ammonia was 10 parts. The mass average particle diameter of the substrate particles 10 was 3.0 μm, and the CV value was 2.5%.

Synthesis Example 10
The base particle 10 (organic matter) was prepared in the same manner as in Synthesis Example 1 except that the amount of 25% aqueous ammonia was 10 parts, and that the monomer component emulsion was prepared with 100 parts of 1,6-hexanediol dimethacrylate. Inorganic composite particles) were obtained. The base particle 10 had a mass average particle size of 3.0 μm and a CV value of 2.7%.

Example 1
120 g of the base particle 1 obtained in Synthesis Example 1 was placed in a chamber type processing container having a capacity of 500 L. The thickness of the particle layer was 0.5 mm. After reducing the pressure in the chamber to 1 Pa, fluorine (F ₂ ) and oxygen (O ₂ ) were introduced so that F ₂ : 13.33 Pa (0.1 Torr) and O ₂ : 80 kPa (600 Torr). F ₂ is 0.017% by volume, and the balance is O ₂ . Then, the process was performed for 60 minutes at 30 degreeC. Thereafter, the inside of the chamber was replaced with nitrogen and then returned to atmospheric pressure. Of the particles after gas treatment, 7 g was put into a 500 ml separable flask, and ion-exchanged water was added to 350 g (particle concentration 2 mass%), and ultrasonic dispersion was performed at room temperature (about 25 ° C.) for 10 minutes. Subsequently, it heated at 85 degreeC, heat-processed for 3 hours, and wash | cleaned the particle | grains (contact process with a water | moisture content). After cooling to room temperature, the particles were filtered, and the cake obtained was washed in the order of ion-exchanged water and methanol, and then vacuum-dried at 80 ° C. for 12 hours to make hydrophilic according to Example 1. Fine particles 1 were obtained.

Example 2
A hydrophilization treatment was performed in the same manner as in Example 1 except that F ₂ was changed to 133.3 Pa (1 Torr) and 0.17% by volume to obtain hydrophilized fine particles 2 according to Example 2.

Example 3
Hydrophilic microparticles 3 according to Example 3 were obtained in the same manner as in Example 2 except that the base particle 2 was used instead of the base particle 1.

Example 4
Hydrophilic microparticles 4 according to Example 4 were obtained in the same manner as in Example 1 except that F ₂ was changed to 0.67 kPa (5 Torr) and 0.83% by volume.

Examples 5 to 11
Hydrophilic microparticles 5 to 11 according to Examples 5 to 11 were obtained in the same manner as in Example 4 except that the base particles 2 to 8 obtained in Synthesis Examples 2 to 8 were used instead of the base particles 1. .

Comparative Example 1
The hydrophilization treatment 1 was carried out in the same manner as in Example 1 except that F ₂ was changed to 1.33 kPa (10 Torr) and 1.64 vol% to obtain comparative hydrophilized fine particles 1 according to Comparative Example 1. It was.

Comparative Example 2
5 g of the base particle 1 obtained in Synthesis Example 1 was taken, dispersed in 45 g of methanol, 0.5 g of 3-aminopropyltrimethoxysilane was added, and the mixture was heated at 100 ± 2 ° C. for 2 hours with stirring. After cooling to room temperature, it was filtered and the resulting cake was washed with methanol. Vacuum drying was performed at 80 ° C. for 12 hours to obtain comparative hydrophilized fine particles 2 according to Comparative Example 2.

Comparative Example 3
0.5 g of the base particle 1 obtained in Synthesis Example 1 is taken and added to 100 ml of an oxidation treatment mixture prepared in advance so as to be 200 ml / l of sulfuric acid and 400 g / l of chromic acid, followed by heat treatment at 70 ° C. for 5 minutes. went. After cooling to room temperature, the mixture was filtered, and the resulting fine particles were washed with water. Vacuum drying was performed at 80 ° C. for 12 hours to obtain comparative hydrophilized fine particles 3 according to Comparative Example 3.

<Characteristic evaluation method>
The following characteristics were evaluated for the base particles obtained in each synthesis example and the hydrophilized fine particles obtained in the examples and comparative examples, and are shown in Tables 1 to 3.

[Mass average particle diameter, CV value]
The mass average particle diameter and CV value were measured by the same method as in Synthesis Example 1.

[Particle shape]
The particles were observed using an electron microscope, and the shape was visually determined.

[Dispersibility in water]
30 g of ion-exchanged water was put into a screw tube having a capacity of 50 cc, 0.1 g of particles were added, and the dispersion state of the particles in water was visually observed. ○ when most of the particles are familiar with water, △ when most of the particles are familiar with water, but some particles remain floating on the water △, most of the particles are above the water The floating thing was evaluated as x.

[Hydrophobicity]
Put 50 cc of ion-exchanged water in a 200 cc glass beaker with a stirrer on the bottom, float 0.2 g of particles on the water surface, sink the tip of the burette in the water in the beaker, and gently rotate the stirrer 5 minutes after the addition of the particles, methanol was gradually introduced from the burette. The introduction of methanol was continued until the total amount of particles on the water surface was completely submerged, and the amount of methanol introduced (cc) when the particles completely submerged in water was measured, and the degree of hydrophobicity was determined based on the following equation. In addition, before adding methanol from the burette, when the particles floating on the water surface completely sink in water, the degree of hydrophobicity was set to zero.
Hydrophobic degree (%) = methanol introduction amount (cc) × 100 / {amount of water (cc) + methanol introduction amount (cc)}

[Changes in color]
The color of the particles before and after the hydrophilic treatment was evaluated by visual observation. A sample with no change in color was marked with ◯, a sample with a slight yellowish color was marked with Δ, and a sample with a completely discolored color was marked with ×.

[Total fluorine content, elutable fluorine content, non-eluting fluorine content]
The total fluorine amount and the eluting fluorine content were determined by the above-described method, and the difference was defined as the non-eluting fluorine content.

[Acid value (KOH neutralization amount)]
Ultrapure water (prepared with “PURELITE” PRA-0015-000 manufactured by Organo Corporation, 18.2 MΩ · cm or less) was added to the weighed 0.5 g of sample particles to adjust the total amount to 50 g, followed by sonication. 10 minutes. Next, neutralization titration was performed using an automatic titrator (Hiranuma Sangyo Co., Ltd., COM-1600), the amount of addition of the titration solution when the potential change amount was maximized, and the acid value was calculated by the following formula. . As the titrant, a 0.005M KOH aqueous solution was used.

[Confirmation of carboxyl group and carboxylate]
Using an X-ray photoelectron spectrometer (ESCA; manufactured by ULVAC-PHI; scanning X-ray photoelectron spectrometer; PHI Quantera SXM ^™ (Scanning X-ray Microprobe)) on the surface of the base material particles after hydrophilization treatment The presence or absence of the formation of carboxyl groups and carboxylates was confirmed.

[Surface existence rate of C, O, F atoms]
Using an X-ray photoelectron spectrometer (ESCA; manufactured by JEOL; JPS-9000MC), the abundance (mol%) of C, O and F atoms on the surface of the base particles and the hydrophilized fine particles was measured. Was used to calculate the relative surface abundance (%) of each atom.

Relative surface abundance of C atoms (%) = 100 × [abundance of C atoms (mol%) / (abundance of C atoms (mol%) + abundance of O atoms (mol%) + abundance of F atoms (mol) %))]
Relative surface abundance of O atoms (%) = 100 × [abundance of O atoms (mol%) / (abundance of C atoms (mol%) + abundance of O atoms (mol%) + abundance of F atoms (mol %))]
F-relative surface abundance (%) = 100 × [F atom abundance (mol%) / (C atom abundance (mol%) + O atom abundance (mol%) + F atom abundance (mol %))]

[10% compression modulus (10% K value: hardness)]
A circular plate indenter with a diameter of 50 μm per sample particle spread on a sample table (material: SKS flat plate) at room temperature (25 ° C.) by a Shimadzu micro-compression tester (manufactured by Shimadzu Corporation, “MCTW-500”) (Material: diamond) Using a load at a constant load speed (2.275 mN / sec) toward the center of the particle, the load when the particle is deformed until the compression displacement becomes 10% of the particle diameter And the amount of displacement (mm) is measured. The measured compression load, particle compression displacement, and particle radius are expressed as follows:

(Where E: compression elastic modulus (N / mm ² ), F: compression load (N), S: compression displacement (mm), R: radius of particle (mm)). calculate. This operation is performed on three different particles, and the average value is set as the 10% compression modulus of the base particles.

[Compressive fracture load]
A load was applied to the particles in the same manner as the compression modulus, and the load (mN) when the particles were broken by deformation was taken as the compression failure load.

[Compression deformation recovery rate (recovery rate)]
Using a micro-compression tester (manufactured by Shimadzu Corporation: “MCTW-500”), after compressing the sample particles to a reverse load of 9.8 mN, measure the relationship between the load value and the compression displacement when the load is reduced. Displacement to the point of reversal when measuring the end point when removing the load as the origin load value of 0.098 mN and the compression (recovery) speed at load and removal as 1.486 mN / sec. It is a value expressed as a ratio (L1 / L2) (%) between (L1) and the displacement (L2) from the reversal point to the point where the origin load value is taken.

The hydrophilized fine particles obtained in Examples 1 to 11 had a degree of hydrophobicity of 0 due to the hydrophilization treatment, and there was almost no change in color. When each hydrophilized fine particle was analyzed by XPS (ESCA), a carbon peak corresponding to a carboxyl group was observed at 288 eV. Further, the mechanical strength of each fine particle hardly changed before and after the treatment. On the other hand, in Comparative Example 1, since the volume% of fluorine in the mixed gas exceeded the specified range, the particle skeleton was damaged by oxidation and turned black. In Comparative Example 2, the particles were subjected to silane coupling treatment. However, hydrophilicity was insufficient and non-uniform, and many particles were not dispersed in water. Further, in Comparative Example 3 in which the oxidation / hydrophilization treatment with chromic acid was performed, the surface of the particles was sufficiently hydrophilic, but the compressive fracture load and recovery rate of the particles decreased compared with those before the chromic acid treatment. I found out.

Examples 12-17
120 g of the base particle 9 obtained in Synthesis Example 9 was placed in a chamber type processing container having a capacity of 500 L. Except that the composition of the mixed gas and the temperature of the gas in the chamber were the conditions shown in Table 4, gas treatment was performed in the same manner as in Example 1 to obtain hydrophilized fine particles 12 to 17. In Examples 12 to 17, the cleaning treatment with ion-exchanged water after the gas treatment was not performed.

In Table 4, Reference Example 1 shows the measurement results of various physical properties of the base particle 9.

From Table 4, the fine particles obtained in Examples 12 to 17 had a hydrophobicity of 0 due to the hydrophilization treatment. That is, it can be seen that when the mixed gas contains an inert gas, the hydrophilization treatment proceeds in the same manner, and hydrophilized fine particles are obtained. In addition, the mechanical strength of each fine particle hardly changed before and after the treatment. Further, when the surfaces of the hydrophilized fine particles of Examples 12 to 17 were analyzed using XPS (ESCA), a carbon peak corresponding to a carboxyl group was observed at 288 eV. Furthermore, from the result of the relative surface abundance ratio (%) of each atom, the base particle after the hydrophilization treatment has a relatively increased oxygen atom amount compared with that before the hydrophilization treatment, and a carboxyl group is generated. It was confirmed that

Further, when the amount of elution fluorine was measured, it was 1.83 mg / g for the hydrophilized fine particles 12, and 1.50 mg / g for the hydrophilized fine particles 14.

Examples 18-21
Same as Example 16 except that the temperature of the mixed gas was changed to −20 ° C. (Example 18), 0 ° C. (Example 19), 20 ° C. (Example 20), and 40 ° C. (Example 21). Then, gas treatment was performed to obtain hydrophilized fine particles 18 to 21. Also in Examples 18 to 21, washing with ion-exchanged water after gas treatment was not performed.

When XPS (ESCA) was used to analyze the abundance of various atoms on the surface of the base particles after the hydrophilic treatment, a carbon peak corresponding to a carboxyl group was observed at 288 eV. Moreover, it was confirmed that the oxygen atom amount relatively increased and the fluorine atom amount decreased as the temperature of the mixed gas during the hydrophilization treatment increased (Table 5).

Examples 22 and 23
7 g of hydrophilized fine particles 12 were immersed in 85 ° C. ion exchange water, and washed with stirring at 85 ° C. for 3 hours (particle concentration: 6.3% by mass). Thereafter, washing with ion-exchanged water and methanol was performed in this order, and further, vacuum drying was performed at 80 ° C. for 12 hours to obtain hydrophilic fine particles 22.
The hydrophilic fine particles 14 were also washed in the same warm water to obtain hydrophilic fine particles 23.

Examples 24 and 25
7 g of hydrophilized fine particles 12 were immersed in a 0.25N aqueous sodium hydroxide solution (particle concentration: 2% by mass) and subjected to alkali treatment at 85 ° C. for 3 hours with stirring. After filtering the particles, they were immersed in ion-exchanged water at 85 ° C. (particle concentration: 6.3% by mass) and washed at the same temperature for 3 hours. After cooling to room temperature, the particles were filtered, washed with ion-exchanged water and methanol in this order, and further vacuum-dried at 80 ° C. for 12 hours to obtain hydrophilized fine particles 24.

The hydrophilic fine particles 14 were also subjected to the same alkali treatment and warm water washing to obtain the hydrophilic fine particles 25.
The eluting fluorine amount of the hydrophilized fine particles 12, 14 and 22 to 25 was measured. The results are shown in Table 6.

From Table 6, it can be seen that the amount of elutable fluorine is the largest in Examples 12 and 14 where no alkali treatment or warm water washing was performed, and can be reduced by performing alkali treatment or warm water washing. Moreover, it turns out that the reduction effect of the amount of elution fluorine becomes high in order of warm water washing | cleaning, an alkali treatment, and warm water washing | cleaning.

Examples 26-28
120 g of the base particle 10 obtained in Synthesis Example 10 was placed in a chamber type processing container having a capacity of 500 L. Hydrophilic particles 26 to 28 were obtained by carrying out gas treatment in the same manner as in Example 1 except that the composition of the mixed gas and the temperature of the gas in the chamber were the conditions shown in Table 4. In Examples 26 to 28, no cleaning treatment with ion-exchanged water after gas treatment was performed.

In Table 7, Reference Example 2 shows the measurement results of various physical properties of the base particle 10.

From Table 7, the microparticles obtained in Examples 26 to 28 had a hydrophobicity of 0 due to the hydrophilization treatment. That is, it can be seen that when the mixed gas contains an inert gas, the hydrophilization treatment proceeds in the same manner, and hydrophilized fine particles are obtained. In addition, the mechanical strength of each fine particle hardly changed before and after the treatment. When the surface of the hydrophilized fine particles obtained in Examples 26 to 28 was analyzed using XPS (ESCA), a carbon peak corresponding to a carboxyl group was observed at 288 eV. In addition, from the results of the relative surface abundance ratio (%) of each atom, the base particle after the hydrophilization treatment has a relatively increased oxygen atom amount as compared with that before the hydrophilization treatment, and the formation of carboxyl groups It could be confirmed. In addition, the elution fluorine amount of the hydrophilized fine particles 26 was 3.76 mg / g.

From the XPS (ESCA) analysis results of Examples 15 and 16 (Table 4) and Examples 27 and 28 (Table 7), the monomer component is styrene-based (aromatic compared to acrylate-based substrate particles). The base particles of the divinyl compound) have a greater increase in the presence of O atoms after hydrophilization than the original base particles (before hydrophilization) under the same hydrophilization conditions, and the presence of F atoms. It can be seen that the ratio is high, the monomer component is highly reactive to the mixed gas of styrene-based substrate particles, and is easily hydrophilized.

Example 29
7 g of the hydrophilized fine particles 26 were immersed in 85 ° C. ion exchange water (particle concentration: 6.3% by mass) and washed with stirring at 85 ° C. for 3 hours. Thereafter, ion-exchanged water and methanol were washed in this order, and further vacuum-dried at 80 ° C. for 12 hours to obtain hydrophilized fine particles 29.

Example 30
7 g of hydrophilized fine particles 26 were immersed in a 0.25N aqueous sodium hydroxide solution (particle concentration: 2% by mass) and subjected to alkali treatment at 85 ° C. for 3 hours with stirring. After filtering the particles, they were immersed in ion-exchanged water at 85 ° C. (particle concentration: 6.3% by mass) and washed at the same temperature for 3 hours. After cooling to room temperature, the particles were filtered, washed with ion-exchanged water and methanol in this order, and further vacuum-dried at 80 ° C. for 12 hours to obtain hydrophilized fine particles 30.
The amount of elution fluorine of the obtained hydrophilized fine particles 26, 29 and 30 was measured. The results are shown in Table 8.

From Table 8, it can be seen that the amount of leaching fluorine can be reduced by the washing treatment, and the fluorine reduction effect by the washing treatment is similar to that in the case where the substrate particles contain a styrene-based monomer. It turns out that it increases in order of when both are performed.
In addition, as a result of performing surface elemental analysis on each particle obtained in Examples 24, 25, and 30 by XPS (ESCA), the presence of Na was confirmed.

The method of the present invention is a useful method that can increase the degree of hydrophilicity of the particle surface by a simple method without impairing the excellent mechanical properties of the particle. Since the hydrophilized fine particles obtained by the method of the present invention have extremely high hydrophilicity, they can be used as various fine particles in the field of electronic materials such as additives for water-based paints or conductive particle substrates.

Claims

This is a method for producing hydrophilized fine particles by hydrophilizing the surface of the base particle by subjecting the base particle to contact with a mixed gas essentially containing a fluorine gas and a compound gas containing oxygen atoms. And
A method for producing hydrophilized fine particles, characterized in that vinyl polymer fine particles having a mass average particle diameter of 1000 μm or less are used as substrate particles, and the fluorine gas concentration in the mixed gas is 0.01 to 1.0% by volume.
The method for producing hydrophilized fine particles according to claim 1, wherein the gas of the compound containing oxygen atoms is oxygen gas.
The method for producing hydrophilized fine particles according to claim 1 or 2, wherein after the treatment of bringing the mixed gas into contact with the base material particles, a treatment of bringing into contact with moisture is performed.
The method for producing hydrophilized fine particles according to claim 3, wherein the moisture is an alkaline aqueous solution.
The method for producing hydrophilized fine particles according to claim 3 or 4, wherein the moisture is water and / or water vapor.
A hydrophilized fine particle obtained by the production method according to any one of claims 1 to 5.