JP6758558B2 - Silica gel porous particles and their manufacturing method - Google Patents

Description

The present invention relates to porous silica gel particles and a method for producing the same.

A porous body having through holes through which a porous structure communicates is used for various purposes. Such porous bodies include those made of organic polymers (Patent Document 1 and the like) and those made of silica gel (Patent Documents 2 and 3 and the like). Further, in recent years, a particulate porous body has been proposed. For example, a method of crushing the produced porous body into a particulate form (Patent Document 2) and a method of producing a particulate porous body from the beginning (Patent Document 2). There is Patent Document 3).

JP 2013-020960 Japanese Unexamined Patent Publication No. 2014-148456 Japanese Unexamined Patent Publication No. 2015-3860

A porous body having through holes through which a porous structure communicates has an advantage that it is easier to handle than a massive porous body in applications such as a packing material for a separation column for chromatography and a column reactor. However, the method of crushing the produced porous body into particles has a problem that the produced porous body particles are irregular and the filling rate is low. Further, in the method of producing a particulate porous body from the beginning, a skin layer may be formed on the particle surface and the pores may be closed.

Therefore, an object of the present invention is to provide silica gel porous particles having through holes, having a uniform shape and not closing the through holes, a method for producing the same, and a block copolymer for use in the production method. That is.

In order to achieve the above object, the porous particles of the present invention are substantially spherical porous particles, and the porous particles are formed of silica gel, and a through hole through which a porous structure communicates is formed therein. The feature is that the end portion of the through hole is open toward the outside of the porous particles.

The method for producing porous particles of the present invention is
A dispersion preparation step of preparing a dispersion by dispersing a porous particle raw material containing at least one of a silica monomer and a silica prepolymer in a dispersion medium, and a polymerization step of polymerizing the porous particle raw material in the dispersion. The method for producing porous particles of the present invention, which comprises the above and forms the through holes by spinodal decomposition in the polymerization step.

The block copolymer of the present invention is a block copolymer formed by containing a hydrophobic polymer block and a hydrophilic polymer block, and the porous particles are prepared in the dispersion liquid preparation step of the method for producing porous particles of the present invention. A block copolymer used as a dispersant for dispersing raw materials in a dispersion medium.

The silica gel porous particles of the present invention have through holes inside, have a substantially spherical and homogeneous shape, and the through holes are not closed. Further, according to the method for producing porous particles of the present invention and the block copolymer of the present invention, it is possible to produce the porous particles of the present invention having the above-mentioned characteristics.

FIG. 1 is an enlarged photograph (magnification: 100 times) of a cross section of the porous silica gel particles produced in the examples. FIG. 2 is an enlarged photograph (magnification: 1000 times) of a cross section of the porous silica gel particles produced in the examples. FIG. 3 is an enlarged photograph (magnification of 5000 times) of a cross section of the porous silica gel particles produced in the examples. FIG. 4 is an enlarged photograph (magnification of 10000 times) of the cross section of the porous silica gel resin particles produced in the examples.

Hereinafter, the present invention will be described with reference to an example. However, the present invention is not limited by the following description.

[1. Silica gel porous particles]
As described above, the silica gel porous particles of the present invention (hereinafter, may be simply referred to as “porous particles” or “porous particles of the present invention”) are substantially spherical. The porous particles of the present invention have, for example, a major axis (longest diameter) of 1.6 times or less, 1.4 times or less, or 1.2 times or less of a minor axis (shortest diameter). Ideally, the porous particles of the present invention are, for example, spherical and have the same major axis and minor axis.

The particle size (particle size) of the porous particles of the present invention is not particularly limited, but the lower limit of the average particle size is, for example, 0.5 μm, 5 μm, 7 μm, 1,000 μm (1 mm), etc. The upper limit is, for example, 30,000 μm (30 mm), 10,000 μm (10 mm), 1,000 μm (1 mm), 700 μm, or the like. The range of the particle size (particle size) of the porous particles of the present invention is, for example, 0.5 to 30,000 μm (0.5 μm to 30 mm), 1 to 10 mm, 5 to 1,000 μm, or 7 to 700 μm. Is. Further, in the present invention, the average particle size can be measured by, for example, a laser diffraction / scattering type particle size distribution measuring device. Alternatively, if it is difficult to measure with a laser diffraction / scattering particle size distribution measuring device due to a small amount of sample, the average particle size may be estimated from a scanning electron micrograph (SEM) image.

As described above, the porous particles of the present invention are formed of silica gel, have through holes through which the porous structure communicates, and the ends of the through holes are outside the porous particles. It opens toward. The through hole has, for example, a bent structure as a result of the perforated structure communicating with each other. Further, the porous particles of the present invention are not particle-aggregated structures, but are porous particles having a co-continuous structure (the porous structure communicates inside the particles) and having through holes. In the present invention, the "particle agglomeration type" porous structure means that small particles having no pores in the particles are bonded to each other to form a skeleton, and at the same time, pores are formed as gaps between the particles. The structure that is used. In the "particle agglomerate type" porous structure, those in which the outer shape of the aggregate of the particles is substantially granular are referred to as particle agglomerate type particles.

The fact that the porous particles of the present invention have through holes through which the porous structure communicates can be confirmed, for example, by a photograph of a cross section or a surface of the porous particles of the present invention. Further, it can be confirmed, for example, by a photograph of the surface of the porous particles of the present invention that the end portion of the through hole is open toward the outside of the porous particles. The porous particles of the present invention, for example, have an opening toward the outside of the porous particles without blocking the ends of the through holes due to the absence of a skin layer (a layer covering the particle surface). are doing. The presence or absence of this skin layer can also be confirmed by a photograph of the surface of the porous particles of the present invention. Further, it is preferable that the porous particles are separated from each other without being bonded to other porous particles.

Further, the porous particles of the present invention may be an aggregate of a plurality of porous particles that are separated from each other without being bonded to other porous particles. Among the aggregates of the porous particles, the number of substantially spherical porous particles (porous particles of the present invention) is, for example, more than 50%, or 70% or more, 80% or more, 90% or more, and the like. You may.

In the porous particles of the present invention, the through holes through which the porous structures communicate may be, for example, a macropore connected to each other and an open cell structure having mesopores in the walls of the macropores. The hole diameter of the through hole is not particularly limited, but is in the range of, for example, 10 to 1,000,000 nm (1 mm), 20 to 100,000 nm, or 30 to 50,000 nm. The pore diameter of the through hole may be hereinafter also referred to as "pore diameter". As will be described later, the pore diameter is influenced by various elements at the time of producing the porous particles of the present invention, and the pore diameter can be adjusted by adjusting the various elements. The pore diameter is usually non-uniform, and the degree of uniformity (dispersion) varies depending on, for example, the effect of heat distribution in the system and stirring in the polymerization reaction during the production of the porous particles of the present invention.

The porosity (porosity) of the porous particles of the present invention is not particularly limited, but is, for example, 30 to 95% by volume, 35 to 90% by volume, or 40 to 85% by volume. The porosity (porosity) can be measured by, for example, a nitrogen adsorption method, a mercury intrusion method, a liquid chromatography method, or the like.

As described above, the material of the porous particles of the present invention is silica gel. That is, the porous particles of the present invention may be formed, for example, by silica gel or by containing silica gel. In the present invention, when the term "silica gel" is simply used, the silica gel may be, for example, inorganic silica or hybrid silica unless otherwise specified. The inorganic silica refers to silica gel containing no organic group in the molecule, and the hybrid silica refers to silica gel containing an organic group in the molecule (for example, side chain). Further, the inorganic silica and the hybrid silica may or may not contain a hetero atom such as a nitrogen atom or a sulfur atom in the molecule, respectively. Further, the porous particles of the present invention may be composed of, for example, a single polymer, but may be a mixture or a copolymer of a plurality of polymers. The copolymer may be, for example, a random copolymer or a block copolymer.

Further, the porous particles of the present invention may or may not contain components other than the polymer (silica gel). The other components are not particularly limited, but are, for example, inorganic fillers (silica, calcium carbonate, talc, alumina, titanium oxide, carbon black, etc.) and organic fillers (acrylic resin particles, urethane resin, etc.). Particles, etc.), nanofibers (carbon nanofiber, cellulose nanofibers, etc.) and the like.

The method for producing the porous particles of the present invention is not particularly limited, but for example, the method for producing the porous particles of the present invention can be used.

[2. Method for producing porous particles]
As described above, the method for producing porous particles of the present invention includes a dispersion liquid preparation step of preparing a dispersion liquid by dispersing a porous particle raw material containing at least one of a monomer and a prepolymer in a dispersion medium, and the porous material. A polymerization step of polymerizing a sex particle raw material in the dispersion liquid is included, and in the polymerization step, the through holes are formed by spinodal decomposition.

In the method for producing porous particles of the present invention, for example, in the dispersion liquid preparation step, the porous particle raw material is dispersed in a dispersion medium together with a dispersant. The dispersant may be, for example, a surfactant.

In the method for producing porous particles of the present invention, for example, the dispersant may be a block copolymer of the present invention formed by containing a hydrophobic polymer block and a hydrophilic polymer block. In this case, for example, the method for producing porous particles of the present invention further comprises a dispersant manufacturing step for producing the dispersant (block copolymer of the present invention), and the dispersant manufacturing step is carried out by living radical polymerization. After the first living radical polymerization step of forming one of the hydrophobic polymer block and the hydrophilic polymer block and the first living radical polymerization step, the other of the hydrophobic polymer block and the hydrophilic polymer block is subjected to living radical polymerization. It may include a first living radical polymerization step of forming the above. Since the block copolymer of the present invention is formed containing a hydrophobic polymer block and a hydrophilic polymer block, it can be said to be a "surfactant" in a broad sense.

According to the production method of the present invention, it is possible to produce porous particles having through holes through which the porous structure communicates, having a substantially spherical outer shape, and having no skin layer. This mechanism is unknown, but it is presumed that, for example, the interface between the porous particle raw material and the dispersion medium can be maintained in an appropriate state. Specifically, for example, by maintaining the interface in an appropriate state, it is considered that the through holes can be formed because the porous particle raw materials can be polymerized without agglomeration. Further, for example, since the porous particle raw material can be maintained in a state of being dispersed in the dispersion medium in the form of particles, it is considered that substantially spherical porous particles of the present invention can be produced. Further, for example, if one of the hydrophilic substance or the hydrophobic substance in the porous particle raw material is unevenly distributed at the interface, the skin layer may be formed by causing polymerization or the like. This skin layer tends to close the through holes on the surface of the porous particles. However, the formation of a skin layer can be prevented by controlling the ratio of the hydrophilic substance to the hydrophobic substance to an appropriate state at the interface. However, this mechanism is an example and does not limit the present invention in any way.

The method for maintaining the interface between the porous particle raw material and the dispersion medium in an appropriate state is not particularly limited, but for example, the block copolymer (dispersant) of the present invention, which is the surfactant or a surfactant in a broad sense. ) Can be mentioned. Further, in the surfactant or the block copolymer (dispersant) of the present invention, it is preferable to appropriately control the ratio of the hydrophobic portion to the hydrophilic portion as described later. Further, as a method of maintaining the interface between the porous particle raw material and the dispersion medium in an appropriate state, for example, a method of physically stirring the dispersion liquid and the like can be mentioned.

In the present invention, "spinodal decomposition" refers to a phenomenon in which a multi-component mixed system forms a co-continuous structure and undergoes phase separation (for example, a two-component mixed system separates into two phases), or a state in which the two-component mixed system is phase-separated. "Spinodal decomposition" may refer to, for example, a process of two-phase separation that occurs when a two-component mixed system is rapidly cooled from a high temperature to an unstable state, but the present invention is not limited to the case of rapid cooling. That is, in the present invention, the method for causing the spinodal decomposition is not particularly limited, and any method may be used. For example, by polymerizing or cross-linking the porous particle raw material while the porous particle raw material is dispersed in the dispersion medium and the interface between the porous particle raw material and the dispersion medium is maintained in an appropriate state. It is considered that spinodal decomposition occurs and the structure is fixed. The method for maintaining the interface between the porous particle raw material and the dispersion medium in an appropriate state is, for example, as described above.

Hereinafter, the method for producing porous particles of the present invention will be described in more detail.

[2-1. Dispersion]
In the production method of the present invention, first, a porous particle raw material containing at least one of a monomer and a prepolymer is dispersed in a dispersion medium to prepare a dispersion liquid (dispersion liquid preparation step). The monomer and prepolymer are not particularly limited, and examples thereof include monomers and prepolymers corresponding to the silica gels. More specifically, for example, TMOS (tetramethoxysilane), TEOS (tetraethoxysilane), MTMS (methoxysilane), SQ (silsesquioxane) and the like can be mentioned. Examples of the raw material monomer of the organic / inorganic hybrid system include organoalkoxysilanes such as methyltrimethoxysilane, vinyltrimethoxysilane, dimethyldimethoxysilane, and 1,2-bistrimethoxysilylethane, and silane coupling agents. Examples thereof include a combination of an organic polymer compound containing a reaction part and silica, and these can be used, for example, as a raw material monomer for hybrid silica. The dispersion medium is not particularly limited, and examples thereof include an organic solvent and water, which may be used alone or in combination of two or more. Examples of the organic solvent include hydrocarbon solvents such as hexane, octane, decane, dodecane, isodecane, cyclohexane, methylcyclohexane, toluene, xylene, ethylbenzene, and cumene; methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and the like. Alcohol-based solvents such as hexanol, benzyl alcohol, cyclohexanol; ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol propyl ether, jigglime. , Triglime, dipropylene glycol dimethyl ether, butyl carbitol, butyltriethylene glycol, methyldipropylene glycol, methylcellosolve acetate, propylene glycol monomethyl ether acetate, dipropylene glycol butyl ether acetate, diethylene glycol monobutyl ether acetate and other glycol solvents; diethyl ether , Dipropyl ether, methylcyclopropyl ether, tetrahydrofuran, dioxane, anisole and other ether solvents; methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, acetophenone and other ketone solvents; methyl acetate, ethyl acetate, butyl acetate, etc. Ester solvents such as propyl acetate, methyl butyrate, ethyl butyrate, caprolactone, methyl lactate, ethyl lactate; halogenated solvents such as chloroform and dichloroethane; amide solvents such as dimethylformamide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone and caprolactam ; Dimethyl sulfoxide, sulfolane, tetramethylurea, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl carbonate, nitromethane, acetonitrile, nitrobenzene, dioctylphthalate and the like can be mentioned, and only one type may be used or two or more types may be used in combination.

The concentration of the porous particle raw material (at least one of the monomer and the prepolymer) in the dispersion is not particularly limited, but is, for example, 0.01 to 10,000 g / L, 1 to 5, with respect to the dispersion medium. It is 000 g / L, or 5 to 3,000 g / L.

Further, in the method for producing porous particles of the present invention, for example, in the dispersion liquid preparation step, the porous particle raw material may be dispersed in a dispersion medium together with a dispersant. The concentration of the dispersant is not particularly limited, but is, for example, 1 to 500 g / L, 2 to 300 g / L, or 3 to 250 g / L with respect to the dispersion medium.

The dispersant may be, for example, a surfactant. The surfactant is not particularly limited, but is, for example, an anionic surfactant, a cationic surfactant, a nonionic surfactant, a block copolymer composed of a hydrophilic block and a hydrophobic block, for example, a polyacrylic acid block and a polyacrylic ester. Examples thereof include a block copolymer composed of blocks, a block copolymer composed of a polyoxyethylene block and a polyacrylic ester block, a block copolymer composed of a polyoxyethylene block and a polyoxypropylene block, and the like.

Examples of the anionic surfactant include fatty acid salts, sulfate ester salts of higher alcohols, phosphate ester salts of fatty alcohols, alkylallyl sulfonates, formalin condensed naphthalene sulfonates and the like. Examples of the cationic surfactant include an alkyl primary amine salt, an alkyl secondary amine salt, an alkyl tertiary amine salt, an alkyl quaternary ammonium salt, and a pyridinium salt. Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters and the like. Examples of the polymer surfactant include partially saponified polyvinyl alcohol, starch, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and partially saponified polymethacrylate.

By selecting the surfactant to be used, the average particle size and particle size distribution of the obtained porous silica gel particles and the aggregated state of the particles can be controlled. For example, an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be controlled. By using an activator, the average particle size can be reduced and the particle size distribution can be narrowed. Further, by using a polymer surfactant, the average particle size can be increased and the aggregation of particles can be suppressed. In particular, when a block copolymer composed of a hydrophilic block and a hydrophobic block is used as the surfactant, it can be emulsified with a small amount of addition, so that the viscosity of the solution during the polymerization reaction can be kept low, and stirring is easy. It is preferable.

Only one type of these surfactants may be used, or two or more types may be used in combination.

Further, for example, the dispersant may be a block copolymer formed by containing a hydrophobic polymer block and a hydrophilic polymer block. In this case, for example, the method for producing porous particles of the present invention further comprises a dispersant manufacturing step for producing the dispersant, wherein the dispersant manufacturing step is carried out by living radical polymerization to obtain the hydrophobic polymer block and hydrophilicity. After the first living radical polymerization step of forming one of the sex polymer blocks and the first living radical polymerization step, the second living which forms the other of the hydrophobic polymer block and the hydrophilic polymer block by living radical polymerization. It may include a radical polymerization step. The block copolymer (dispersant) and the dispersant manufacturing process will be described in [2-2. Block copolymer (dispersant) and dispersant manufacturing process] will be described in detail.

Further, in the dispersion liquid preparation step, the dispersion liquid may contain components other than the porous particle raw material and the dispersant. The other components are not particularly limited, and examples thereof include surfactants other than nonionic activators, antifoaming agents, and the like as long as they do not affect the original dispersion.

[2-2. Block copolymer (dispersant) and dispersant manufacturing process]
The block copolymer (dispersant) and the dispersant manufacturing process will be described in detail below.

First, since the block copolymer is formed by containing a hydrophobic polymer block and a hydrophilic polymer block, it can be said to be a "surfactant" in a broad sense as described above. Further, the block copolymer and the dispersant manufacturing process may be, for example, the same as or according to the description in JP-A-2015-83688, or may be referred to. Specifically, for example, it is as follows.

The block copolymer is, for example, the hydrophobic polymer block (hereinafter, may be simply referred to as "hydrophobic block" or "hydrophobic block A" or "A block")-the hydrophilic polymer block (hereinafter, simply "". It may be a diblock copolymer composed of "hydrophilic block" or "hydrophilic block B" or "B block"). The block copolymer is obtained by polymerizing an addition polymerizable monomer using a radical generator, for example, using an organic iodide as a polymerization initiation compound and an organic phosphorus compound, an organic nitrogen compound or an organic oxygen compound as a catalyst. It may be.

The content of the A block (hydrophobic block) in the block copolymer molecule is, for example, 5 to 95% by mass, 10 to 90% by mass, 15 to 85% by mass, or 20 to 80% by mass. The content of the B block (hydrophilic block) in the block copolymer molecule is, for example, 5 to 95% by mass, 10 to 90% by mass, 15 to 85% by mass, or 20 to 80% by mass. ..

The hydrophobic monomer that is the raw material of the A block (hydrophobic block) is, for example, a (meth) acrylate ((meth) acrylic acid ester) having a hydrophobic group, a vinyl compound having a hydrophobic group, and an allyl having a hydrophobic group. Compounds, etc. may be mentioned. The hydrophilic monomer which is a raw material of the B block (hydrophilic block) is, for example, a (meth) acrylate having a hydrophilic group ((meth) acrylic acid ester), a vinyl compound having a hydrophilic group, an allyl compound having a hydrophilic group, and the like. And so on. For example, the hydrophobic monomer may contain lauryl (meth) acrylate, and the hydrophilic monomer may contain polyethylene glycol methacrylate. In the present invention, "(meth) acrylic" means one or both of "acrylic" and "methacryl", and "(co) polymerization" means one or both of "polymerization" and "copolymerization". means. The same applies to "(meth) acrylate". Further, "(poly) alkylene ........." means one or both of "alkylene ........." and "polyalkylene .........". The same applies to “(poly) ethylene ………”.

As described above, the dispersant (block copolymer) has a diblock structure formed by containing the hydrophobic polymer block A and the hydrophilic polymer block B (hereinafter, may be referred to as “AB diblock polymer”). )is there. For example, in the dispersion preparation step, the dispersant (block copolymer) is dispersed in the dispersion medium together with the porous particle raw material (including at least one of a monomer and a prepolymer). When the porous particle raw material is relatively hydrophilic with respect to the dispersion medium, for example, the hydrophilic polymer block B is adsorbed on the porous particle raw material, and the particles formed by aggregating the porous particle raw material The surface is coated with the hydrophobic polymer block A. As a result, the hydrophobic polymer block A becomes a form facing the hydrophobic dispersion medium. On the contrary, when the porous particle raw material is relatively hydrophobic with respect to the dispersion medium, for example, the hydrophobic polymer block A is adsorbed on the porous particle raw material and the porous particle raw material is aggregated. The surface of the particles is coated with the hydrophilic polymer block B. As a result, the hydrophilic polymer block B faces the hydrophilic dispersion medium. In this way, the porous particle raw material can be in a state of being dispersed in the dispersion medium in the form of particles. This state can also be said to be, for example, a state in which the porous particle raw material is emulsified (suspended) in the dispersion medium. Thereby, for example, the dispersion stability and storage stability of the dispersion liquid before and after the polymerization can be improved.

The porous particle raw material (including at least one of the monomer and the prepolymer) is as described above. For example, the porous raw material is at least one of the radically polymerizable or thermosetting monomer and the prepolymer. May include. Further, the monomer and prepolymer may be, for example, a hydrophilic monomer and prepolymer.

Next, in the method for producing the block copolymer (dispersant), for example, as described above, an organic iodide is used as a polymerization initiator compound, an organic phosphorus compound, an organic nitrogen compound or an organic oxygen compound is used as a catalyst, and a radical generator is used. The method may be a method of polymerizing an addition-polymerizable monomer (hydrophobic monomer and hydrophilic monomer). Such a production method is described in, for example, Japanese Patent Application Laid-Open No. 2015-83688. According to this manufacturing method, there are no problems such as heavy metals, odor, coloring, and cost. Specifically, for example, there are the following advantages (1) to (6).

(1) Do not use heavy metal compounds; do not use heavy metal compounds such as ATRP method and DT method.
(2) Purification is not essential; the ATRP method and DT method require removal of heavy metals, and the RAFT method and MADIX method require removal of sulfur compounds.
(3) No special and expensive compounds are required, relatively inexpensive materials on the market can be used and therefore low cost; other living radical polymerization methods require special compounds.
(4) The polymerization conditions are mild, and the polymerization can be carried out under the same conditions as the conventional radical polymerization method; the NMP method requires a high temperature, and the ATRP method requires the removal of oxygen.
(5) It is not necessary to purify the monomers and solvents used, various monomers can be used, and monomers having various functional groups such as acid groups and amino groups can be used, and various polymers can be used in the polymer block. A functional group can be introduced; especially in the ATRP method, the acid group becomes its catalytic poison, and the acid group cannot be used as it is. Methacrylate does not polymerize well in the NMP method.
(6) The molecular weight and structure can be controlled, a block polymer in a desired bonded state can be easily obtained, and the polymerization rate is very good.

The above description is an example, and in the present invention, the method for producing the block copolymer (dispersant) is not particularly limited. That is, the method for producing the block copolymer (dispersant) is not limited to the method described in JP-A-2015-83688, and any production method may be used.

The hydrophobic monomer forming the A block is not particularly limited, and for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, 2 -Methylpropane (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl ( Meta) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tetradecyl (meth) acrylate, octadecyl (meth) acrylate, behenyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, t -Butylcyclohexyl (meth) acrylate, isobolonyl (meth) acrylate, 2,2,4-trimethylcyclohexyl (meth) acrylate, cyclodecyl (meth) acrylate, cyclodecylmethyl (meth) acrylate, benzyl (meth) acrylate, t-butyl Examples thereof include aliphatic, alicyclic, aromatic alkyl (meth) acrylates such as benzotriazole phenylethyl (meth) acrylate, phenyl (meth) acrylate, naphthyl (meth) acrylate, and allyl (meth) acrylate. Those having a long alkyl group such as meta) acrylate are preferable. Only one type of the hydrophobic monomer may be used, or a plurality of types may be used in combination.

The hydrophilic monomer constituting the B block is not particularly limited, and examples thereof include a monomer having a polyglycol group, and more specifically, for example, poly (n = 2 or more) ethylene glycol mono (meth) acrylate. Poly (n = 2 or more) propylene glycol mono (meth) acrylate, poly (n = 2 or more) tetramethylene glycol mono (meth) acrylate, mono or poly (n = 2 or more) polyethylene glycol mono or poly (n = 2 or more) ) Mono (meth) acrylate of propylene glycol random copolymer, mono (meth) acrylate of mono or poly (n = 2 or more) ethylene glycol mono or poly (n = 2 or more) mono (meth) acrylate of propylene glycol block copolymer, etc. (Meta) acrylate, as well as (poly) ethylene glycol monomethyl ether (meth) acrylate, (poly) polyethylene glycol monooctyl ether (meth) acrylate, (poly) ethylene glycol monolauryl ether (meth) acrylate, (poly) ethylene glycol Monostearyl ether (meth) acrylate, (poly) polyethylene glycol monooleyl ether (meth) acrylate, (poly) polyethylene glycol monostearic acid ester (meth) acrylate, (poly) polyethylene glycol monononylphenyl ether (meth) acrylate, ( Poly) propylene glycol monomethyl ether (meth) acrylate, (poly) propylene glycol monoethyl ether (meth) acrylate, (poly) propylene glycol monooctyl ether (meth) acrylate, (poly) propylene glycol monolauryl ether (meth) acrylate, Examples include (polyalkylene) glycol monoalkyl such as (poly) ethylene glycol (poly) propylene glycol monomethyl ether (meth) acrylate, alkylene, alkyn ether or ester mono (meth) acrylate, and particularly poly (n = 6 or more). ) Polyethylene glycol mono (meth) acrylate is desirable. In addition, said n represents the degree of polymerization in said said polyglycol group. Further, the hydrophilic monomer may be used alone or in combination of two or more.

Further, the block copolymer (dispersant) may be formed only from the hydrophobic polymer block A (A block) and the hydrophilic polymer block B (B block), but may include other components ( It may be (copolymerized). Examples of the monomer that can be copolymerized within the range that does not change the basic properties of the A block and the B block include conventionally known monomers, for example, styrene, vinyl toluene, vinyl hydroxybenzene, chloromethyl styrene, vinyl naphthalene, and vinyl. Biphenyl, vinyl ethyl benzene, vinyl dimethyl benzene, α-methyl styrene, ethylene, propylene, isoprene, butene, butadiene, 1-hexene, cyclohexene, cyclodecene, dichloroethylene, chloroethylene, fluoroethylene, tetrafluoroethylene, acrylonitrile, methacrylonitrile, Vinyl-based monomers such as vinyl acetate, vinyl propionate, isocyanatodimethylmethane isopropenylbenzene, phenylmaleimide, cyclohexylmaleimide, and hydroxymethylstyrene, and hydroxyl-containing monomers include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl. (Meta) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate, cyclohexanediol mono (meth) acrylate, etc. The above-mentioned (poly) alkylene glycol mono (meth) such as (meth) acryloyloxyethyl mono or poly (n = 2 or more) caprolactone as the mono (meth) acrylic acid ester of the alkylene glycol of the above, and other monomers. ) Acrylate-based mono (meth) acrylic acid ester obtained by ring-opening polymerization of lactones such as ε-caprolactone and γ-butyrolactone; 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalate and The above-mentioned (poly) alkylene glycol mono (meth) acrylic acid ester such as 2- (meth) acryloyloxyethyl-2-hydroxyethyl succinate is reacted with a dibasic acid to form a half ester, and then the other Ester-based (meth) acrylate in which alcohol and alkylene glycol are reacted with a carboxyl group; mono (meth) of a polyfunctional hydroxyl group having three or more hydroxyl groups such as glycerol mono (meth) acrylate and dimethylol propane mono (meth) acrylate. ) Acrylate; 3-chloro-2-hydroxypropyl (meth) acrylate, octafluorooctyl (meth) ac Halogen element-containing (meth) acrylates such as relate, tetrafluoroethyl (meth) acrylate; 2- (4-benzoxy-3-hydroxyphenoxy) ethyl (meth) acrylate, 2- (2'-hydroxy-5- (meth)) Monomers that absorb ultraviolet light, such as acryloyloxyethylphenyl) -2H-benzotriazole, especially this monomer, may be copolymerized to improve the light resistance of the dye; α-hydroxyl methyl, such as ethyl-α-hydroxymethylacrylate. Substituted acrylates and the like can be mentioned.

The molecular weight of the block copolymer (dispersant) is not particularly limited, but is a styrene-equivalent number average molecular weight in gel permeation chromatography (hereinafter, GPC) (hereinafter, the number average molecular weight refers to GPC in terms of styrene, and is simply referred to as molecular weight). For example, 1,000 or more, 1,500 or more, 2,000 or more or 3,000 or more, for example, 300,000 or less, 100,000 or less, or 50,000 or less. The molecular weight range is, for example, 1,000 to 300,000, preferably 1,500 to 100,000, more preferably 2,000 to 50,000, still more preferably 3,000 to 50,000. From the viewpoint of dispersion stability of the porous particle raw material in the dispersion medium, the molecular weight of the block copolymer (dispersant) is preferably 1,000 or more. Further, from the viewpoint of the solubility of the block copolymer (dispersant) in the dispersion medium, the molecular weight of the block copolymer (dispersant) is preferably 300,000 or less. If the molecular weight of the block copolymer (dispersant) is too large, the dispersants in the dispersion medium may be aggregated and the molecules may be entangled with each other so that the porous particle raw material cannot be dispersed.

The degree of dispersion (hereinafter referred to as PDI), which is the ratio of the weight average molecular weight to the number average molecular weight, in the block copolymer (dispersant) is not particularly limited. In living radical polymerization, a very small PDI (~ 1.3) polymer dispersant can be used, but in the present invention, it is important that the block copolymer (dispersant) has the above-mentioned block structure. PDI is not significantly involved. However, if the PDI is too wide, the block copolymer (dispersant) will contain a polymer having a large molecular weight to a polymer having a small molecular weight, and a phenomenon other than the above-mentioned molecular weight range may occur, which is not preferable. In the block copolymer (dispersant) used in the present invention, the PDI is preferably 2.0 or less, more preferably 1.8 or less.

Next, the mass ratio of the hydrophobic block to the hydrophilic block in the block copolymer (dispersant) is not particularly limited, but is as described above, for example. By appropriately controlling the mass ratio of the hydrophobic block to the hydrophilic block, for example, in the method for producing porous particles of the present invention, the interface between the porous particle raw material and the dispersion medium is maintained in an appropriate state. can do. As a result, for example, the porous particle raw material can be maintained in a state of being dispersed in the dispersion medium in the form of particles, so that the porous particles of the present invention can be produced in a substantially spherical shape. Further, for example, by appropriately controlling the mass ratio of the hydrophobic block to the hydrophilic block, the ratio of the hydrophilic substance to the hydrophobic substance can be appropriately controlled at the interface between the porous particle raw material and the dispersion medium. It can be controlled to the state. For example, if either a hydrophilic substance or a hydrophobic substance is unevenly distributed at the interface, the skin layer may be formed by causing polymerization or the like. This skin layer tends to close the through holes on the surface of the porous particles. However, the formation of a skin layer can be prevented by controlling the ratio of the hydrophilic substance to the hydrophobic substance to an appropriate state at the interface. However, these explanations are examples and do not limit the present invention.

Next, a polymerization method (manufacturing method) for obtaining the block copolymer (dispersant) used in the present invention will be described. This polymerization method is not particularly limited, but for example, as described above, an addition polymerizable monomer using an organic iodide as a polymerization initiator compound, an organic phosphorus compound, an organic nitrogen compound or an organic oxygen compound as a catalyst, and a radical generator. It may be a method of polymerizing (hydrophobic monomer and hydrophilic monomer). This polymerization method does not use a metal compound or a ligand, and does not require the use of special compounds such as nitroxide, dithiocarboxylic acid ester, and zantate, and is a conventional addition polymerizable monomer and a polymerization initiator which is a radical generator. It is a living radical polymerization that can be easily carried out by simply using a starting compound which is an organic iodide and a catalyst in combination with the radical polymerization using the above.

The above polymerization method is described in the following general reaction formula 1
It proceeds by the reaction mechanism represented by, and is considered to be a reversible active reaction of the Dormant species Polymer-X (PX) to the growth radical. This polymerization mechanism may change depending on the type of catalyst, but it is considered that the process proceeds as follows. In the above formula 1, P · generated from the polymerization initiator reacts with XA to generate catalyst A · on site. A. acts as an activator of PX, and this catalytic action activates PX with high frequency.

More specifically, in the presence of the initiator compound to which iodine (X) is bound, radicals generated from the polymerization initiator abstract the active hydrogen and active halogen atoms of the catalyst to become the catalyst radical A. Then, the A. extracts the X of the starting compound to become XA, the starting compound becomes a radical, the monomer polymerizes on the radical, and X is immediately extracted from XA to prevent the termination reaction. Further, A. Extracts X from the terminal X by heat or the like, becomes XA and a terminal radical, and the monomer reacts there, and immediately gives X to the terminal radical to stabilize it. By repeating this process, polymerization proceeds and the molecular weight and structure can be controlled. However, in some cases, a side reaction may be accompanied by a bimolecular termination reaction or disproportionation.

The starting compound for initiating the living radical polymerization is a conventionally known organic iodide and is not particularly limited. Specifically, methyl iodide, ethyl iodide, propyl iodide, isopropyl iodide, butyl iodide, t-butyl iodide; iodophenylmethane, iododiphenylmethane, iodotriphenylmethane, 2-iodo Alkyl iodides such as -1-phenylethane, 1-iodo-1-phenylethane, 1-iodo-1,1-diphenylethane, diiodomethane; iodo dichloromethane, iodochloromethane, iodotrichloromethane, iododibromomethane Organic halides containing iodine atoms such as 1-iodoethanol, 1-iodopropanol, 2-iodopropanol, 2-iodo-2-propanol, 2-iodo-2-methylpropanol, 2-phenyl-1. -Alcohol iodides such as iodoethanol and 2-phenyl-2-iodoethanol; ester compounds of these iodide alcohols with carboxylic acid compounds such as acetic acid, butyric acid and fumaric acid; iodoacetic acid, α-iodopropion Acid, α-iodobutyric acid, α-iodoisobutyric acid, α-iodoisovaleric acid, α-iodoisovaleric acid, α-iodocaproic acid, α-iodophenylacetic acid, α-iododiphenylacetic acid, α-iodo-α -Phenylpropionic acid, α-iodo-β-phenylpropionic acid, β-iodopropionic acid, β-iodobutyric acid, β-iodoisobutyric acid, β-iodovaleric acid, β-iodoisovaleric acid, β-iodocaproic acid , Β-Iodophenylacetic acid, β-iododiphenylacetic acid, β-iodo-α-phenylpropionic acid, β-iodo-β-phenylpropionic acid and other iodide carboxylic acids; these iodide carboxylic acids methanol, ethanol , Phenol, benzyl alcohol, and esterified products such as the above-mentioned iodide alcohol; acid anhydrides of those iodide carboxylic acids; acid anhydrides of those iodide carboxylic acids such as chloride and bromide; iodo acetonitrile, 2 Examples thereof include cyano group-containing iodides such as −cyano-2-iodopropane, 2-cyano-2-iodobutane, 1-cyano-1-iodocyclohexane, and 2-cyano-2-iodovaleronitrile. Bifunctional initiator compounds having two iodines can also be used, for example, 1,2-diaiodoethane, 1,2-diaiodotetrafluoroethane, 1,2-diaiodotetrachloroethane, 1,2-diaiodo-1-. Examples thereof include phenylethane, a reaction product of a carboxylic acid iodide such as α-iodoisobutyric acid and a diol such as ethylene glycol, and a diamine such as hexamethylenediamine. In addition, "iodine" is synonymous with "iodine" and represents iodide. The same applies below. Further, the starting compound may be used alone or in combination of two or more.

Further, as these compounds, for example, commercially available products may be used as they are, or they can be obtained by a conventionally known method. For example, an organic halide obtained by reacting an azo compound such as azobisisobutyronitrile with iodine, or in which the above-mentioned iodine of the organic iodide is replaced with another halogen atom such as bromide or chloride is used. An organic iodide used in the present invention can be obtained by performing a halogen exchange reaction using an iodide salt such as quaternary ammonium iodide or sodium iodide. They are not particularly limited.

The catalyst is, for example, an organic phosphorus compound, an organic nitrogen compound, or an organic oxygen compound that abstracts the iodine atom of the starting compound and becomes a radical, preferably a phosphorus halide containing an iodine atom or a phosphite compound. , Phosphinate compound, organic phosphorus compound, imide compound, hydantoin compound, organic nitrogen compound, phenol compound, iodooxyphenyl compound, vitamins, organic oxygen compound. Is done. These compounds are not particularly limited, and specific examples thereof include phosphorus halides containing an iodine atom, phosphite compounds, and phenylate compounds, and examples thereof include dichloroiodrine and dibromoiodrine. Phosphorus triiodide, dimethylphosphite, diethylphosphite, dibutylphosphite, diperfluoroethylphosphinate, diphenylphosphite, dibenzylphosphite, bis (2-ethylhexyl) phosphite, bis (2,2,2) -Trifluoroethyl) phosphite, diallyl phosphite, ethylene phosphite, ethoxyphenylphosphinate, phenylphenoxyphosphinate, ethoxymethylphosphinate, phenoxymethylphosphinate and the like. The nitrogen compounds are imide-based compounds and hydantoin-based compounds, for example, succinimide, 2,2-dimethylsuccinimide, α, α-dimethyl-β-methylsuccinimide, 3-ethyl-3-methyl-2,5-pyrrolidindione, Sis-1,2,3,6-tetrahydrophthalimide, α-methyl-α-propylsuccinimide, 5-methylhexahydroisoindole-1,3-dione, 2-phenylsuccinimide, α-methyl-α-phenylsuccinimide, 2,3-diacetoxysuccinimide, maleimide, phthalimide, 4-methylphthalimide, N-chlorophthalimide, N-bromophthalimide, N-bromophthalimide, 4-nitrophthalimide, 2,3-naphthalenecarboxyimide, pyromellitic diimide, 5 -Bromoisoindole-1,3-dione, N-chlorosuccinimide, N-bromosuccinimide, N-iodosuccinimide, hydantin, diiaidohydantin and the like can be mentioned. Examples of the oxygen compound include a phenolic compound which is a phenolic hydroxyl group having a hydroxyl group in the aromatic ring, an iodooxyphenyl compound which is an iodide of the phenolic hydroxyl group, and vitamins. For example, the phenols include phenol, hydroquinone, and methoxy. Hydroquinone, t-butylphenol, t-butylmethylphenol, catechol, resorcinol, di-t-butylhydroxytoluene, dimethylphenol, trimethylphenol, di-t-butylmethoxyphenol, hydroxystyrene polymer polymer or its hydroxyphenyl group support Examples include polymer fine particles. Since these are added as polymerization inhibitors for the preservation of the monomer, the effect can be exhibited by using the commercially available monomer as it is without purification. Examples of the iodooxyphenyl compound include timoldiaiodide, and examples of vitamins include vitamin C and vitamin E.

The amount of the catalyst is not particularly limited, but is, for example, less than the number of moles of the polymerization initiator. If the number of moles of the catalyst is too large, the polymerization may be controlled too much and the polymerization may not proceed.

Next, the polymerization initiator used in the present invention is not particularly limited, and for example, conventionally known polymerization initiators such as organic peroxides and azo compounds, which are usually used, can be used. Specific examples include benzoyl peroxide, dicumyl peroxide, diisopropyl peroxide, di-t-butyl peroxide, t-butylperoxybenzoate, t-hexylperoxybenzoate, and t-butylperoxy-2-ethylhexa. Noate, t-hexylperoxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis (t) -Butylperoxy) hexyl-3,3-isopropylhydroperoxide, t-butylhydroperoxide, dicumylhydroperoxide, acetylperoxide, bis (4-t-butylcyclohexyl) peroxydicarbonate, isobutylperoxide , 3,3,5-trimethylhexanoyl peroxide, lauryl peroxide, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (isobutyrate), 2, Examples thereof include 2'-azobis (methoxydimethylvaleronitrile), and only one type may be used or two or more types may be used in combination.

The amount of the polymerization initiator used is not particularly limited, but is, for example, 0.001 to 0.1 mol times, more preferably 0.002 to 0.05 mol times, the number of moles of the monomer. If the amount of the polymerization initiator used is too small, the polymerization may be insufficient, and if it is too large, a polymer containing only the addition polymerization monomer may be formed.

As described above, the block copolymer (dispersant) used in the present invention can be obtained by polymerizing using at least an initiator compound, an addition-polymerizable monomer, a polymerization initiator and a catalyst which are organic iodides. The above polymerization may be carried out in bulk without using an organic solvent, but solution polymerization using a solvent is preferable. The organic solvent used is not particularly limited, and any solvent may be used as long as it dissolves the organic iodide, catalyst, addition-polymerizable monomer and polymerization initiator used in the present invention. Examples of the organic solvent are hydrocarbon solvents such as hexane, octane, decane, isodecane, cyclohexane, methylcyclohexane, toluene, xylene, ethylbenzene, cumene; methanol, ethanol, propanol, isopropanol, butanol, isobutanol, hexanol, benzyl. Alcohol-based solvents such as alcohol and cyclohexanol; ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol propyl ether, jiglime, triglime, Glycol solvents such as dipropylene glycol dimethyl ether, butyl carbitol, butyltriethylene glycol, methyldipropylene glycol, methylcellosolve acetate, propylene glycol monomethyl ether acetate, dipropylene glycol butyl ether acetate, diethylene glycol monobutyl ether acetate; diethyl ether, dipropyl Ether solvents such as ether, methyl cyclopropyl ether, tetrahydrofuran, dioxane, anisole; ketone solvents such as methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, acetophenone; methyl acetate, ethyl acetate, butyl acetate, propyl acetate, etc. Ester solvents such as methyl butyrate, ethyl butyrate, caprolactone, methyl lactate, ethyl lactate; halogenated solvents such as chloroform and dichloroethane; amide solvents such as dimethylformamide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone and caprolactam; dimethylsulfoxide , Sulfolane, tetramethylurea, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl carbonate, nitromethane, acetonitrile, nitrobenzene, dioctylphthalate and the like, and may be used alone or in combination of two or more.

The solid content (monomer concentration) of the polymerization solution is not particularly limited, but is, for example, 5 to 80% by mass, preferably 20 to 60% by mass. From the viewpoint of smoothly completing the polymerization, it is preferable that the monomer concentration is not too low. Further, from the viewpoint of preventing the viscosity of the polymerization solution from becoming too high, making stirring difficult, and the polymerization rate from becoming poor, it is preferable that the monomer concentration is not too high.

The polymerization temperature is not particularly limited, and is 0 ° C. to 150 ° C., more preferably 30 ° C. to 120 ° C. The polymerization temperature is adjusted by the half-life of each polymerization initiator. The polymerization time is preferably continued until the monomer is exhausted, but is not particularly limited, and is, for example, 0.5 hour to 48 hours, preferably 1 hour to 24 hours as a practical time, and more preferably 2 hours. Hours to 12 hours.

The atmosphere of the polymerization reaction is not particularly limited, and for example, the polymerization may be carried out as it is in the atmosphere, that is, oxygen may be present in the system within a normal range, and oxygen may be removed if necessary. Therefore, it may be carried out under a stream of nitrogen or argon. Further, as the material to be used, impurities may be removed by distillation, activated carbon or alumina, but a commercially available product can be used as it is. Further, the polymerization may be carried out under light shielding, or may be carried out in a transparent container such as glass without any problem.

The operation and mechanism of the method (polymerization method) for producing the block copolymer (dispersant) are as follows, for example. First, using a monofunctional organic iodide as an starting compound, an addition-polymerizable monomer having at least an acid group is polymerized by the above method to obtain one polymer block (referred to as A block). Since the polymer terminal is substituted with an iodine group, it is stabilized, and the monomer can be added again and dissociated by heat or the like, or a small amount of radical initiator is added to initiate the polymerization again.

The A block is taken out, purified, dissolved again in an organic solvent, and the following monomer is added as the starting compound, preferably a catalyst and a polymerization initiator are added for polymerization, thereby polymer-terminated iodine. Dissociates and polymerization starts again, and a diblock polymer in which the B block is linked to the A block can be obtained. Further, after forming the A block, the block copolymer (dispersant) can be obtained by adding the B block monomer as it is without taking out the polymer, and preferably adding a catalyst and a polymerization initiator to carry out the polymerization.

Similarly, the formation of the above blocks is reversed, and the B block monomer, which is a hydrophilic polymer, is first polymerized, and then the monomer containing at least the monomer having a hydrophobic group is polymerized to form the AB diblock. A polymer (the block copolymer) may be obtained.

In the polymerization used in the present invention, for example, the molecular weight of the polymer can be controlled by the amount of the starting compound. More specifically, for example, by setting the number of moles of the monomer with respect to the number of moles of the starting compound, an arbitrary molecular weight or the magnitude of the molecular weight can be controlled. For example, when 1 mol of the starting compound is used and 500 mol of a monomer having a molecular weight of 100 is used for polymerization, a theoretical molecular weight of 1 × 100 × 500 = 50,000 is given, that is, as a set molecular weight,
[1 mol of starting compound x molecular weight of monomer x molar ratio of monomer to starting compound]
Can be calculated with.

However, the polymerization method used in the present invention may be accompanied by a side reaction of bimolecular termination or disproportionation, and may not reach the above theoretical molecular weight. A polymer that does not have these side reactions is preferable, but it may be coupled to increase the molecular weight, or it may be stopped to decrease the molecular weight. Further, the polymerization rate does not have to be 100%, and the remaining monomer is distilled off, removed when the block polymer is precipitated, or a desired block polymer is obtained, and then a polymerization initiator or a catalyst is added. The polymerization may be completed. The diblock polymer used in the present invention may be produced and contained, and there is no problem even if each block polymer unit is contained. The block copolymer (dispersant) containing 50% by mass or more, more preferably 80% by mass or more of the block polymer of the present invention may be preferable. Further, the PDI is widened by accompanying the above-mentioned side reaction, but the PDI is not particularly limited, and is preferably 2.0 or less, more preferably 1.8 or less.

As described above, the diblock polymer which is the block copolymer (dispersant) used in the present invention is polymerized by using an organic iodide as an initiator compound and at least using an addition polymerizable monomer, a polymerization initiator and a catalyst. Can be obtained. However, as described above, this production method (polymerization method) is arbitrary, and the block copolymer (dispersant) used in the present invention may be produced by any method.

[2-3. Production of porous particles by polymerization]
Specifically, the method for producing porous particles of the present invention can be carried out, for example, as follows.

First, a porous particle raw material containing at least one of a monomer and a prepolymer is dispersed in a dispersion medium to which the block copolymer (dispersant) is previously added to prepare a dispersion liquid (dispersion liquid preparation step). The porous particle raw material is as described above. Specifically, in the dispersion liquid preparation step, specifically, for example, a porous particle raw material containing at least one of a silica monomer and a silica prepolymer and containing a solvent serving as a pologene, and the block copolymer (dispersant) are added in advance. The porous particle raw material is dispersed in the hydrophobic organic solvent in the form of particles by mixing with the hydrophobic organic solvent (dispersion medium). Then, for example, the dispersion liquid is heated to perform the polymerization step. Then, porous particles made of silica gel are obtained by polymerization (polymerization step). Then, if necessary, the solvent, unreacted material, etc. are removed from the porous particles.

The silica monomer and silica prepolymer as raw materials are as described above. Of these, silica monomers and silica prepolymers that are soluble in porogen are particularly preferred.

In the present invention, the term "pologen" refers to an inert solvent or mixture of inert solvents as a pore-forming agent. Porogen is present during a polymerization reaction that forms a porous polymer at some stage of polymerization, and by removing it from the reaction mixture at a given stage, it is a porous body with a three-dimensional network structure and communicating voids. Is obtained.

In the present invention, the porogen is, for example, a solvent capable of dissolving the porous particle raw material and causing reaction-induced phase separation after the porous particle raw material is polymerized. Examples of the pologene include cellosolves such as methyl cellosolve and ethyl cellosolve, esters such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, and glycols such as polyethylene glycol and polypropylene glycol. Among them, polyethylene glycol, methyl cellosolve, ethyl cellosolve, ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate having a molecular weight of about 200 to 20,000 are preferable, and polyethylene glycol and propylene glycol monomethyl ether acetate having a molecular weight of about 200 to 20,000 are particularly preferable. preferable. Only one type of the porogen may be used, or two or more types may be used in combination.

In the present invention, it is desirable to use a polyalkylene glycol or a polyalkylene glycol derivative having a hydroxyl group and having a hydroxyl value of 100 (mgKOH / g) or more as the porogen. When the hydroxyl value is smaller than 100 (mgKOH / g), the viscosity becomes high, it becomes difficult to increase the pore size of the formed silica gel porous body, and the effect of imparting hydrophilicity to the silica gel porous body decreases. Sometimes. The amount of hydroxyl groups on the surface of the silica gel porous body and the hydroxyl group equivalent of porogen are closely related, and as the hydroxyl value of porogen decreases, the amount of hydroxyl groups appearing on the surface of the silica gel porous body also decreases, and the hydrophilicity of the surface decreases. It is thought that this is to be done.

Further, as described above, the porous particle raw material contains, for example, at least one of a silica monomer and a silica prepolymer, and also contains a solvent that becomes a porosin. The porous particle raw material can be prepared, for example, by mixing at least one of the silica monomer and the silica prepolymer with the porogen to homogenize it.

The content ratio of the solvent that becomes porosity in the porous particle raw material affects, for example, the pore diameter, pore distribution, etc. of the obtained silica gel porous particles, and when the porosity content is high, the pore diameter is large and small. And the pore diameter tends to be smaller. Further, when the content ratio of porogen is high, the pore distribution tends to be broad, and when it is low, the pore distribution tends to be sharp.

The content ratio of the porosity solvent in the porous particle raw material is usually 50 to 300% by weight, preferably 50 to 300% by weight, based on at least one of the silica monomer and the silica prepolymer contained in the porous particle raw material. More preferably, it is ~ 200% by weight. When the porosity content is at least the above lower limit, a porous structure having a higher porosity can be formed, while when it is at least the above upper limit, the porosity of the obtained porous particles is suppressed to an appropriate range. It can be done and the mechanical strength tends to be improved.

The method for preparing the porous particle raw material is not particularly limited, and a method of mixing at least one of the silica monomer and the silica prepolymer at room temperature or while heating may be adopted, or at room temperature or while heating. A method may be adopted in which at least one of the silica monomer and the silica prepolymer is added to the pologene and mixed or dissolved.

Next, in the dispersion liquid preparation step, for example, if a sufficient shearing force is applied and the mixture is stirred, the porous particle raw material can be dispersed in the form of particles. In this case, an appropriate method can be taken in consideration of the size and particle size distribution of the particles. For example, as the method for dispersing the porous particle raw material, a method that can provide a sufficient shearing force may be used. More specifically, for example, not only a device having stirring blades of various shapes such as a propeller type, a paddle type, a turbine type, and a screw type, but also a rotating / revolving mixer and a test tube bottom swirling at high speed to provide a liquid content. A known method such as a "vortex mixer" for stirring the mixture, ultrasonic stirring, and a membrane emulsification method can be used. It is preferable to select a method in which the particle size is as constant as possible.

In the dispersion liquid adjusting step, as described above, for example, the porous particle raw material and the hydrophobic organic solvent (dispersion medium) to which the block copolymer (dispersant) is added in advance are mixed and the porous. The particle raw material may be dispersed in the form of particles in a hydrophobic organic solvent. The concentration of the block copolymer (dispersant) in the hydrophobic organic solvent (dispersion medium) to which the block copolymer (dispersant) is added in advance is not particularly limited, but is, for example, 1 to 500 g / L as described above. It is 2 to 300 g / L, or 3 to 250 g / L. When the block copolymer concentration is at least the above lower limit, the particle size can be easily controlled and aggregation during polymerization can be suppressed, and when it is at least the above upper limit, bubbles are generated during polymerization and the viscosity is increased. It can be suppressed and easy to manufacture. Then, as described above, the next polymerization step can be carried out in a state where a water-in-oil emulsion in which the porous particle raw material is dispersed in the form of particles in a hydrophobic organic solvent is formed.

Further, in the polymerization step of polymerizing the porous particle raw material in the dispersion liquid, the amount of the dispersant (for example, the block copolymer or the surfactant) used is not particularly limited, but the silica monomer and the silica prepolymer are not particularly limited. , And, for example, about 1 to 20% by weight, or 2 to 10% by weight, based on the total amount of the polymer. The amount of the dispersant used affects, for example, the average particle size and particle size distribution of the obtained porous particles, and the aggregation of the particles. When the amount of the dispersant used is large, the average particle size, particle size distribution, and particle agglomeration can be controlled, and when the amount is small, foaming and viscosity tend to be kept low. Therefore, when the amount of the dispersant used is not more than the above lower limit, the raw material mixture can be uniformly emulsified, the particle size distribution can be narrowed, and the agglomeration of particles can be suppressed. Further, when it is not more than the above upper limit, foaming and an increase in viscosity can be suppressed, and production becomes easy.

In the polymerization step, the reaction temperature is not particularly limited and can be appropriately set. The reaction temperature is basically determined by the raw material monomer and the raw material prepolymer, and also varies depending on the stirring speed, porogen, amount of surfactant used, etc., but is, for example, 20 to 250 ° C., 40 to 220 ° C., or It is 50 to 200 ° C. The heating temperature affects, for example, the pore size of the resulting porous particles. When the heating temperature is high, the pore size of the obtained porous particles tends to be small, and when the heating temperature is low, the pore size of the obtained porous particles tends to be large. When the heating temperature is moderately high, the addition polymerization reaction proceeds smoothly, and when the heating temperature is moderately low, the reaction rate is prevented from becoming too fast, and the porous structure can be formed well.

In the polymerization step, the reaction time is not particularly limited and can be appropriately set. The reaction time varies depending on the stirring speed, heating temperature, porogen, amount of surfactant used, and the like, but is, for example, 0.01 to 100 hr, 0.05 to 24 hr, or 0.1 to 20 hr. The reaction time affects, for example, the reaction rate of the resulting porosity. When the reaction time is long, the reaction rate is high and there are few unreacted substances, so the mechanical strength tends to be high. When the reaction time is short, the reaction rate is low and there are many unreacted substances, so the mechanical strength tends to be low. When the reaction time is moderately long, the addition polymerization reaction proceeds sufficiently to form a desired porous structure, and when the reaction time is moderately short, the possibility of crushing by stirring can be reduced.

Further, in the polymerization step, it is preferable to carry out the reaction while stirring the dispersion liquid. The stirring speed is not particularly limited, and varies depending on the heating temperature, reaction scale, porogen, amount of surfactant used, etc., but for example, 10 to 20,000 rpm, 30 to 10,000 rpm, 50 to 5,000 rpm, 50 to 800 rpm, or 100-400 rpm. In addition, "rpm" represents the number of revolutions per minute. The stirring speed affects, for example, the particle size of the resulting porous particles. Generally, when the stirring speed is high, the particle size of the obtained porous particles tends to be small, and when the stirring speed is low, the particle size of the obtained porous particles tends to be large. When the stirring speed is moderately high, phase separation and the like are suppressed, and a product having a uniform particle size can be obtained. When the stirring speed is moderately low, the particle size is not too small and foaming can be suppressed.

When the polymerization step is completed, as described above, porogens, solvents, unreacted substances and the like are removed from the porous particles, if necessary. Specifically, for example, the dispersion medium containing the porous fine particles is diluted with a large amount of cleaning solvent, and the precipitated particles are separated by a centrifuge repeatedly to sufficiently wash the particles, and then the cleaning is performed with a vacuum dryer. Remove the solvent. The cleaning solvent is preferably a solvent having high solubility in the dispersion medium and porogen, and preferably a solvent having a low boiling point and easy to remove. Specific examples of the cleaning solvent include methyl ethyl ketone and the like. In this way, the porous particles of the present invention can be obtained.

Further, the produced porous particles may be surface-modified by, for example, physical treatment or chemical treatment. The physical or chemical treatment can be performed, for example, for the purpose of improving the properties of the separating agent for chromatography. Examples of the physical treatment or chemical treatment include surface hydrophilicity, surface hydrophobicity, introduction of functional groups, and the like.

The use of the porous particles of the present invention is not particularly limited, but it is very useful as, for example, a novel adsorption / separating agent. More specifically, the porous particles of the present invention can be used, for example, as a separating agent for chromatography. Examples of the object to be separated by the chromatography include separation of biological substances such as proteins, peptides, amino acids and nucleic acids and other chemical substances. The use of the porous particles of the present invention is not limited to this, and for example, a column carrying a filler for cosmetics, a filler for tires, a filler for paints / inks, a base for sustained-release chemicals, and a reaction catalyst. It can be used for various purposes such as a filler for a reactor, a bactericide, and a separator for a battery. In the case of a battery separator, for example, the porous particles of the present invention can be coated on the surface of the electrode to obtain a battery separator.

Hereinafter, examples of the present invention will be described. However, the present invention is not limited to the following examples.

<Synthesis example: Synthesis of AB block copolymer (dispersant)>
An AB block copolymer (dispersant) formed from the hydrophobic polymer block A and the hydrophilic polymer block B was produced (synthesized) as in Synthesis Examples 1 and 2 below. In these block copolymers, all the constituent monomers are (meth) acrylate-based monomers, the A-chain polymer block is a (meth) acrylate having a hydrophobic group, and the B-chain polymer block has a hydrophilic group ( Meta) acrylate is a constituent component. Further, the polystyrene-equivalent number average molecular weight in GPC is 2,000 to 100,000, the PDI is 1.6 or less, and the number average molecular weight of the polymer block A composed of (meth) acrylate having a hydrophobic group. Is less than 80,000 and 20-95% by mass of the total constituents. In the following, the number of copies of each substance is parts by mass (parts by weight) unless otherwise specified.

[Synthesis Example 1]
5.23 parts of toluene, 5 parts of lauryl methacrylate (hereinafter abbreviated as LMA), 0.0495 parts of iodine, 2,2 as a polymerization initiator in a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube. '-Azobis (4-methoxy-2,4-dimethylvaleronitrile) (hereinafter abbreviated as V-70) 0.909 parts, azobisdimethylisobutyvaleronitrile (hereinafter abbreviated as V-65) 0.0183 parts, And 0.0726 part of tetrabutylammonium iodide (hereinafter abbreviated as BNI) was charged, and the mixture was stirred at 60 ° C. while flowing nitrogen. Polymerization for 16 hours gave Polymer Block A. This was sampled, the solid content was measured, and the polymerization conversion rate converted from the non-volatile content was 90%. At this time, the number average molecular weight (hereinafter abbreviated as RI-Mn) of the GPC differential refractometer was 16,500, and the PDI was 1.27.

Next, 2.33 parts of toluene, 9.34 parts of polyethylene glycol methacrylate (hereinafter abbreviated as PEGMA), and 0.121 parts of V-70 were added, and further polymerized at 60 ° C. for 3 hours in the same manner as described above. A chain was formed, the number average molecular weight of the B chain was 2,100, the PDI was 1.28, and the polymerization conversion rate was 87%. In this way, a solution of the AB block copolymer was obtained. This polymerization solution was dissolved in tetrahydrofuran having about the same weight, precipitated in a large amount of methanol, left to stand for a while, and then the supernatant was removed and centrifuged. Then, the obtained precipitate was similarly dissolved in tetrahydrofuran and precipitated in methanol twice, and then the obtained precipitate was dried to form a semi-fluid AB block copolymer (dispersant). Got The yield was 41%. The obtained AB block copolymer had a number average molecular weight of 18,700 and a PDI of 1.27. Hereinafter, the block copolymer (dispersant) of the present synthesis example (synthesis example 1) thus obtained will be referred to as "block copolymer K-1".

[Synthesis Example 2]
Dimethyldiglycol (hereinafter abbreviated as DMDG) 33.4 parts, LMA 100 parts, iodine 1.5 parts, tetrabutylammonium iodide (hereinafter abbreviated as DMDG) 33.4 parts, LMA 100 parts, tetrabutylammonium iodide (hereinafter abbreviated as DMDG) to a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube , BNI) 0.7 part, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) as a polymerization initiator (trade name: V-70, manufactured by Wako Pure Chemical Industries, Ltd.) 3.8 1.0 part of 2,2'-azobis (2,4-dimethylvaleronitrile) (trade name: V-65, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Then, the mixture was stirred while introducing argon gas, and the temperature was raised to 60 ° C. with a mantle heater. The reaction system was kept at 60 ° C. and polymerized for 3 hours to obtain polymer block A. When the progress of the polymerization was calculated by ¹ H-NMR measurement in the reaction system, the polymerization rate was 89%. Further, the molecular weight was calculated by gel permeation chromatography (GPC) measurement (detector: differential refractometer) using a THF solvent, and the number average molecular weight (hereinafter abbreviated as Mn) was 5900 and the weight average molecular weight (hereinafter referred to as Mw). (Omitted) was 8200. Its molecular weight distribution (hereinafter abbreviated as PDI value) was 1.40.

Then, following the above, 147 parts of PEGMA, 0.7 parts of V-65, and 49 parts of DMDG were added to the reaction system, and the mixture was polymerized at 60 ° C. for 1 hour for a predetermined time to form a polymer block B. As a result of calculating the polymerization progress by ^{1 1} H-NMR measurement, the polymerization rate of PEGMA was 23%. Moreover, when the molecular weight was measured from GPC, the Mn of the entire block copolymer was 9700 and the Mw was 12000. The PDI value was 1.24.

337 parts of the polymerization solution obtained as described above is diluted with about the same amount of THF, washed with saturated brine to remove PEGMA unreacted with DMDG, dried over sodium sulfate, concentrated, and dried at 80 ° C. As a result, 118 parts of a polymer additive composed of AB block copolymer was obtained. When DMDG and unreacted PEGMA could not be completely removed by the washing operation, dialysis (dialysis membrane: Spectra / Pore 6, MWCO 1,000) was used in water, and then freeze-dried. Hereinafter, the block copolymer (dispersant) of the present synthesis example (synthesis example 2) thus obtained will be referred to as "block copolymer K-2".

In the following examples, the porous particles of the present invention were produced.

[Example 1]
<Preparation of silica monomer composition>
1.12 g of polyethylene oxide (abbreviation: PEO, weight average molecular weight 10,000) and 10 mL of 0.01 M acetic acid were placed in a 50 ml beaker and dissolved with a stirrer chip. After melting, it was cooled with ice water and stirred while adding 4.5 ml of tetramethoxysilane (abbreviation: TMOS) and stirred until it became a transparent uniform solution (about 15 minutes), and it was confirmed that it became transparent (hydrolysis). Done).

<Dispersion preparation process>
The silica mixture is dissolved in a cylindrical glass sample bottle (inner diameter 19 mm, height 60 mm) in which 0.9 g of the AB block copolymer (dispersant) K-1 is dissolved in 15 g of dodecane as a dispersion medium. In addition, a dispersion was prepared.

<Polymerization process and post-treatment>
The dispersion was stirred at room temperature at 2000 rpm for 10 minutes with a stirring blade, and then the number of revolutions per minute was reduced to 50 rpm and reacted at a high temperature bath temperature of 40 ° C. for 90 minutes to carry out polymerization. As a result, the silica composition dispersed in the form of fine particles solidified in the state of particles. The particles obtained by this polymerization step were placed in MEK and sufficiently stirred, and then the particles were separated using a centrifuge. This washing step with MEK was repeated 10 times to sufficiently remove poroses, residual monomers and the like, and then dried under reduced pressure to obtain 2.6 g of spherical porous particles made of silica gel. The average particle size of the porous particles was 12 μm. In addition, the appearance of the spherical porous particles (spherical fine particles) and SEM photographs of the particle surface are shown in FIGS. 1 to 4. FIGS. 1 to 4 show photographs of the particle surface of this example, respectively. In addition, each figure is a photograph having a magnification of 100 times, 1000 times, 5000 times, and 10000 times, respectively. As shown in each of FIGS. 1 to 4, the silica gel porous particles have through holes through which the porous structure communicates, and there is no skin layer on the surface, and the edges of the through holes are present. The portion was open toward the outside of the porous particles.

[Example 2]
As a dispersant, 2.6 g of spherical porous particles made of silica gel were obtained in the same manner as in Example 1 except that the block copolymer K-2 was used instead of the block copolymer K-1. The average particle size of the porous particles was 11 μm. Further, the appearance of the spherical porous particles (spherical fine particles) and the SEM photographs of the particle surface and the inside of the particles showed the same results as in FIGS. 1 to 4 (Example 1). That is, the silica gel porous particles had through holes through which the porous structure communicated. Further, there was no skin layer on the surface of the silica gel porous particles, and the end portion of the through hole was opened toward the outside of the porous particle.

[Example 3]
Spherical porosity made of silica gel in the same manner as in Example 1 except that the nonionic surfactant "Unilube 10MS-250KB" (trade name of Nichiyu Co., Ltd.) is used as the dispersant instead of the block copolymer K-1. 3.3 g of particles were obtained. The average particle size of the porous particles was 12 μm. Further, the appearance of the spherical porous particles (spherical fine particles) and the SEM photographs of the particle surface and the inside of the particles showed the same results as in FIGS. 1 to 4 (Example 1). That is, the silica gel porous particles had through holes through which the porous structure communicated. Further, there was no skin layer on the surface of the silica gel porous particles, and the end portion of the through hole was opened toward the outside of the porous particle.

The data of Examples 1 to 3 are shown in Table 1 below.

Furthermore, when the porous particles of Examples 1 to 3 were used as a separating agent for chromatography, good separation characteristics could be obtained.

As described above, according to the present invention, there is provided a silica gel porous particle having through holes, a uniform shape and the through holes not being closed, a method for producing the same, and a block copolymer used in the method for producing the same. be able to. The use of the porous particles of the present invention is not particularly limited, but it is very useful as, for example, a novel adsorption / separating agent. More specifically, the porous particles of the present invention can be used, for example, as a separating agent for chromatography. Examples of the object to be separated by the chromatography include separation of biological substances such as proteins, peptides, amino acids and nucleic acids and other chemical substances. The use of the porous particles of the present invention is not limited to this, and for example, a column carrying a filler for cosmetics, a filler for tires, a filler for paints / inks, a base for sustained-release chemicals, and a reaction catalyst. It can be used for various purposes such as a filler for a reactor.

Claims (8)

A method for producing substantially spherical porous particles.
The porous particles have an average particle size of 0.5 to 700 μm.
The porous particles are formed of silica gel, have through holes of a co-continuous structure in which the porous structures communicate with each other, and the ends of the through holes face the outside of the porous particles. is open Te,
The manufacturing method is
A dispersion preparation step of preparing a dispersion by dispersing a porous particle raw material containing at least one of a silica monomer and a silica prepolymer and a pologene in a dispersion medium.
Including a polymerization step of polymerizing the porous particle raw material in the dispersion.
In the dispersion liquid preparation step, the porous particle raw material is dispersed in a dispersion medium together with a dispersant.
A method for producing the porous particles, which comprises forming the through holes by spinodal decomposition in the polymerization step. The production method according to claim 1, wherein the major axis of the porous particles is 1.6 times or less the minor axis. The production method according to claim 1 or 2 , wherein in the dispersion liquid preparation step, the porous particle raw material is dispersed in a dispersion medium together with a dispersant. The production method according to claim 3 , wherein the dispersant is a block copolymer formed by containing a hydrophobic polymer block and a hydrophilic polymer block. Further, the dispersant manufacturing step of manufacturing the dispersant is included.
The dispersant manufacturing step includes a first living radical polymerization step of forming one of the hydrophobic polymer block and the hydrophilic polymer block by living radical polymerization.
The production method according to claim 4 , further comprising a second living radical polymerization step of forming the other of the hydrophobic polymer block and the hydrophilic polymer block by living radical polymerization after the first living radical polymerization step. The production method according to claim 3 , wherein the dispersant is a surfactant. The production method according to claim 6 , wherein the surfactant is a nonionic surfactant. A block copolymer formed by comprising a hydrophobic polymer block and a hydrophilic polymer block, which is used as the dispersant in the production method according to claim 4 or 5 .