WO2021095739A1 - Method for producing polymer fine particles, and dispersion stabilizer - Google Patents

Abstract

Provided is a production method by which polymer fine particles having excellent polymerization stability and a small particle diameter (for example, the average particle diameter is at most 0.20 μm) can be obtained. The production method comprises a step for producing polymer fine particles by polymerizing one or more second vinyl monomers, in the presence of a first polymer having a polymer chain of one or more first vinyl monomers and a unit of living radical polymerization activity, through dispersion polymerization using living radical polymerization based on the living radical polymerization activity. The unit of living radical polymerization activity can be used as an active unit in living radical polymerization through an exchange chain mechanism or a bond-dissociation mechanism.

Description

Method for producing polymer fine particles and dispersion stabilizer

This specification relates to a method for producing polymer fine particles and the like.

(Cross-reference to related applications) This application is a related application of Japanese Patent Application No. 2019-207465 filed on November 15, 2019, and claims priority based on this application. , All the contents described in this application are incorporated.

Polymer fine particles are used in a wide range of fields such as electrical and electronic materials such as conductive fine particles, spacers (for LCD cells, touch panel seals, etc.), resin film modifiers, thickeners (for paints, cosmetics, etc.), etc. It is used in. Conventionally used methods for producing micron-sized or smaller polymer fine particles include an emulsion polymerization method, a suspension polymerization method, a precipitation polymerization method, and a dispersion polymerization method.

In the emulsion polymerization method, a solvent, a polymerizable monomer sparingly soluble in the solvent, and an emulsifier (surfactant) are mixed, and polymerization is carried out using a polymerization initiator soluble in the solvent to obtain nano-order polymer fine particles. However, since it is necessary to use a large amount of a low-molecular-weight emulsifier, there is a concern that the final product may be adversely affected (turbidity, water resistance, etc.). In the suspension polymerization method, droplets are formed by mechanically stirring the polymerizable monomer in water in the presence of a dispersion stabilizer, and polymerization is carried out using an appropriate oil-soluble polymerization initiator. This is a method for obtaining polymer particles. The precipitation polymerization method is a method for obtaining polymer particles in a system in which a polymerizable monomer is dissolved in a solvent, but the obtained polymer is insoluble in a solvent and precipitates. Here, the suspension polymerization method generally obtains polymer particles having a particle size of several tens of μm or more, and the precipitation polymerization method generally obtains polymer particles having a particle size of several μm to several hundred μm, but all of these methods are smaller particles. This is a polymerization method that cannot be applied to applications that require a diameter.

On the other hand, the dispersion polymerization method is a method in which precipitation polymerization is carried out in the presence of a dispersion stabilizer, and the particle size of the produced fine particles can be controlled by the type and amount of the polymerizable monomer, solvent, and dispersion stabilizer. Moreover, the fine particles are characterized by having a narrow particle size distribution.

Various methods are known as methods for producing polymer fine particles by dispersion polymerization. Patent Document 1 describes acrylamide and its derivatives, p-styrene sulfonic acid and its salts, (meth) acrylic acid and their salts, etc. as homopolymers of these monomers or the co-weight of these monomers. As a method of forming a copolymer with a coalescence or a copolymer with another monomer into fine particles, a water-miscible organic solvent such as ethanol is used as a polymerization solvent, and a water-miscible organic solvent or a water-miscible organic solvent is used in advance at the time of polymerization. A method of producing hydrophilic polymer fine particles by allowing a soluble polymer to exist in a miscible solvent with water and polymerizing the above-mentioned monomers is disclosed. The range of the average particle size of the polymer fine particles specifically disclosed in the examples is 0.34 to 2.40 μm.

Patent Document 2 describes the polymerization of acrylamide or acrylic acid neutralized products alone or as a mixture in a mixed solvent of water and a water-miscible organic solvent, using polyvinylpyrrolidone or a polyvinylpyrrolidone copolymer having a weight average molecular weight of 10,000 or more. A method for producing polymer fine particles by performing in the presence of the above is disclosed, and the range of the average particle size of the polymer fine particles specifically disclosed in the examples is 0.7 to 1.30 μm. is there.

Patent Document 3 states that in the presence of a polymer (dispersion stabilizer) obtained by polymerizing a specific monomer in an alcoholic medium, the weight is soluble in the alcoholic medium but is produced. A method for producing monodisperse polymer fine particles by polymerizing one or more kinds of vinyl-based monomers that are insoluble or hardly soluble in the alcohol medium is disclosed, and the coalescence is specifically described in Examples. The range of the average particle size of the polymer fine particles disclosed in the above is 0.19 to 9.0 μm. More specifically, in this dispersion polymerization method, when acrylamide is used as the vinyl-based monomer, polymer fine particles having an average particle diameter of 0.19 μm and 0.20 μm can be obtained, and the vinyl-based simple particle is used. It is disclosed that when ammonium acrylate is used as the metric, polymer fine particles having an average particle diameter of 0.21 μm can be obtained.

In Patent Document 4, a raw material monomer containing a monomer having two or more unsaturated double bonds and an unsaturated monomer having a hydrophilic functional group or an active hydrogen group is dissolved in the raw material monomer. However, the produced polymer is subjected to solution polymerization, preferably dispersion polymerization or similar precipitation polymerization using a polymerization initiator in an insoluble medium, so that the particle size distribution is narrow even without using seed particles, and comparison is made. By efficiently obtaining crosslinked polymer fine particles having a uniformly uniform particle size, and at this time, by adding an organic compound having 5 or more carbon atoms and a melting point of 80 ° C. or less to the reaction system, It is disclosed that the dispersibility of particles is improved, the particle size distribution can be controlled more uniformly, and monodisperse polymer fine particles can be efficiently obtained. The range of the average particle size of the polymer fine particles specifically disclosed in the examples is 2.5 μm to 5.2 μm.

Japanese Unexamined Patent Publication No. 04-132705 Japanese Unexamined Patent Publication No. 04-279604 Japanese Unexamined Patent Publication No. 09-316106 Japanese Unexamined Patent Publication No. 2006-282772

However, the dispersion polymerization methods described in Patent Documents 1, 2 and 4 could not produce polymer fine particles having a small particle size (for example, 0.20 μm or less). Further, according to Patent Document 3, when ammonium acrylate was used as a monomer, the particle size was 0.21 μm.

Further, according to the present inventors, when a vinyl-based monomer other than the vinyl polymer specifically disclosed in Patent Document 3 is used, the dispersibility of the fine particles is lowered during the polymerization reaction. There was a problem of polymerization stability, such as agglomeration. In addition, there is a problem in the degree of freedom in selecting the vinyl-based monomer.

The present specification provides a production method capable of obtaining polymer fine particles having a small particle size (for example, an average particle size of 0.20 μm or less) while having excellent polymerization stability, and a dispersion stabilizer therefor.

The present inventors have focused on a polymer having a polymerizable group, which is used as a dispersion stabilizer, for example. Then, a polymer having a specific living radical polymerization activity unit is used as a dispersion stabilizer, and by using living radical polymerization utilizing the specific living radical polymerization activity and performing dispersion polymerization, secondary in the polymerization step is performed. It was found that polymer fine particles having a small particle size can be stably obtained while suppressing aggregation and the like. According to the present specification, the following means are provided based on such findings.

[1] In the presence of a polymer chain of one or more first vinyl-based monomers and a first polymer having a living radical polymerization active unit, one or more second vinyl-based monomers A step of producing polymer fine particles by polymerizing a monomer by dispersion polymerization using living radical polymerization based on the living radical polymerization activity.
With
The method, wherein the living radical polymerization active unit is an active unit in living radical polymerization by an exchange chain mechanism or a bond-dissociation mechanism.
[2] The method according to [1], wherein the living radical polymerization active unit is living radical polymerization by the exchange chain mechanism.
[3] The method according to [1] or [2], wherein the living radical polymerization active unit is an active unit in living radical polymerization by a reversible addition-cracking chain transfer polymerization method or an iodine transfer polymerization method.
[4] The method according to any one of [1] to [3], wherein the first polymer has a molecular weight distribution of 2.0 or less.
[5] In the step of producing the polymer fine particles, 0.3 parts by mass or more and 50 parts by mass of the first polymer are used with respect to 100 parts by mass of the second vinyl-based monomer of one or more kinds. The method according to any one of [1] to [4], which is used below.
[6] In the step of producing the polymer fine particles, 0.3 parts by mass or more and 20 parts by mass of the first polymer are used with respect to 100 parts by mass of the second vinyl-based monomer of one or more kinds. The method according to [5], which is used below.
[7] The second vinyl-based monomer of one kind or two or more kinds contains acrylic acid or a salt thereof, and the polymerization solvent in the step of producing the polymer fine particles contains acetonitrile, according to [1] to [6]. The method described in either.
[8] The one or more first vinyl-based monomers are selected from the group consisting of styrenes, (meth) acrylonitrile compounds, maleimide compounds, unsaturated acid anhydrides and unsaturated carboxylic acid compounds. The method according to [7], wherein there are two or more kinds of compounds containing styrenes.
[9] The second vinyl-based monomer of one or more kinds is one of [1] to [8] containing acrylic acid of 50% by mass or more and 100% by mass or less of the total mass thereof. The method described.
[10] The method according to [9], wherein the one or more first vinyl-based monomers contain 20% by mass or more of styrenes based on the total mass thereof.
[11] The one or more first vinyl-based monomers contain 20% by mass or more of styrenes based on the total mass of the first vinyl-based monomer, and the one or more second vinyl-based monomers. The body contains acrylic acid or a salt thereof in an amount of 50% by mass or more and 100% by mass or less of the total mass thereof.
The first polymer comprises a living radical polymerization active unit by reversible addition-cleavage chain transfer polymerization.
The method according to [1], wherein 0.3 parts by mass or more and 20 parts by mass or less of the first polymer is used with respect to 100 parts by mass of the first type or two or more kinds of second vinyl-based monomers.
[12] A polymer fine particle comprising a polymer comprising a polymer chain of one or more first vinyl-based monomers and a living polymerization active unit provided in at least a part of the polymer chain. Dispersion stabilizer for use in manufacturing.

The disclosure of the present specification relates to a method for producing polymer fine particles, a dispersion stabilizer, and the like. According to the method for producing polymer fine particles disclosed in the present specification, a polymer chain containing a unit derived from a first vinyl-based monomer (hereinafter, also referred to as a first polymer chain) and a living polymerization active unit. By polymerizing the second vinyl-based monomer in the presence of the first polymer having and, the second vinyl-based monomer is polymerized with the first polymerized chain as a base point, and the polymerized chain is polymerized. (Hereinafter, also referred to as a second polymerized chain) is extended from the living polymerization active unit. The extension of the second polymerized chain forms nuclei of the polymer fine particles, and then the extension of the second polymerized chain and the interaction between the second polymerized chains form particles, and the particle size of the particles increases.

Since the first polymer or the second polymer chain is polymerized by the living radical polymerization based on the active unit in the living radical polymerization by the exchange chain mechanism or the bond-dissociation mechanism, the molecular weight distribution is generally narrow, and the polymer fine particles have a narrow molecular weight distribution. During growth, it acts to stabilize the dispersion of the polymer fine particles. Further, due to the living polymerization activity derived from the first polymer, the polymer fine particles are provided with a first polymer chain and a second polymer chain, and the molecular weight of these polymer chains and the entire polymer chain is excellent. Is obtained.

A polymer having the first polymer chain of the first polymer on the surface layer of the polymer fine particles and the second polymer chain as a core by selecting the type of the first polymer chain and the second polymer chain. Fine particles and the like can be produced.

In the process of producing the polymer fine particles, the monomer, the initiator, etc. are all dissolved in the medium at the start of the polymerization, and the polymer produced by the start of the polymerization is precipitated and aggregated to form particles, which are non-uniform. The above method can be applied to the dispersion polymerization method of forming a solution. At this time, these polymer chains are organized so that the first polymer chain is arranged on the surface layer side of the polymer fine particles and the second polymer chain is arranged inside the polymer fine particles, so that the polymer fine particles are arranged. Is generated and grown. Since the first polymer or the first polymer chain functions as an excellent dispersion stabilizer and the dispersion stability of the polymer fine particles is ensured in the polymer fine particle production step, the average particle size is 0.2 μm or less. Even the polymer fine particles of the above can be easily obtained.

Hereinafter, typical and non-limiting specific examples of the present disclosure will be described in detail. This detailed description is intended to provide those skilled in the art with details for implementing the preferred examples of the present disclosure and is not intended to limit the scope of the present disclosure. In addition, the additional features and inventions disclosed below may be used separately or in combination with other features and inventions in order to provide a further improved "method for producing polymer fine particles and dispersion stabilizer". Can be done.

In addition, the combination of features and processes disclosed in the following detailed description is not essential in carrying out the present disclosure in the broadest sense, and is particularly for explaining typical specific examples of the present disclosure. It is to be described. In addition, the various features of the above and below representative examples, as well as the various features of those described in the independent and dependent claims, are described herein in providing additional and useful embodiments of the present disclosure. It does not have to be combined according to the specific examples given or in the order listed.

All features described herein and / or claims are, separately, as a limitation to the disclosure at the time of filing and the specific matters claimed, apart from the composition of the features described in the examples and / or claims. And it is intended to be disclosed independently of each other. In addition, all numerical ranges and statements relating to groups or groups are made with the intention of disclosing their intermediate composition as a limitation to the disclosure at the time of filing and the specific matters claimed.

Hereinafter, various embodiments disclosed in the present specification will be described in detail. In the present specification, "(meth) acrylic" means acrylic and / or methacrylic, and "(meth) acrylate" means acrylate and / or methacrylate. Further, the “(meth) acryloyl group” means an acryloyl group and / or a methacryloyl group.

(Method for producing polymer fine particles)
The method for producing polymer fine particles disclosed in the present specification (hereinafter, also simply referred to as the present production method) is one or more first vinyl-based monomers (hereinafter, simply referred to as the first method). In the presence of a first polymer chain containing a monomer unit derived from (also referred to as a monomer) and a first polymer having a living polymerization active unit, one or more second vinyl-based single particles. A step of polymerizing a dimer (hereinafter, also simply referred to as a second monomer) to produce polymer fine particles can be provided.

(First polymer) In this method, the first polymer can be used. The first polymer can include a first polymer chain containing units derived from one or more first monomers and a living polymerization active unit. As the first monomer, various vinyl-based monomers can be used without particular limitation, which varies depending on the function and use of the polymer fine particles to be obtained.

(First Polymerized Chain) The first polymerized chain is obtained by polymerizing a monomer composition containing the first monomer. Examples of the first monomer include styrenes, (meth) acrylonitrile compounds, maleimide compounds, unsaturated acid anhydrides and unsaturated carboxylic acid compounds. One or a combination of two or more of these can be used.

Styrenes include styrene and its derivatives. Specific compounds include styrene, α-methylstyrene, β-methylstyrene, vinylxylene, vinylnaphthalene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, pn-butylstyrene, p-isobutylstyrene, pt-butylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-chloromethylstyrene, p-chloromethylstyrene , O-Chlorostyrene, p-chlorostyrene, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, divinylbenzene and the like are exemplified, and one or more of these can be used. Among these, styrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-hydroxystyrene, m-hydroxystyrene, and p-hydroxystyrene are preferable from the viewpoint of polymerizable property.

Examples of the (meth) acrylonitrile compound include (meth) acrylonitrile and α-methylacrylonitrile. For example, acrylonitrile is used.

Maleimide compounds include maleimide and N-substituted maleimide compounds. Specific examples of the N-substituted maleimide compound include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, and N-tert-butyl. N-alkyl-substituted maleimide compounds such as maleimide, N-pentylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, N-stearylmaleimide; N-cyclopentylmaleimide, N-cyclohexylmaleimide, etc. N-Cycloalkyl-substituted maleimide compounds; N-phenylmaleimide, N- (4-hydroxyphenyl) maleimide, N- (4-acetylphenyl) maleimide, N- (4-methoxyphenyl) maleimide, N- (4-ethoxy) Examples thereof include N-aryl-substituted maleimide compounds such as phenyl) maleimide, N- (4-chlorophenyl) maleimide, and N- (4-bromophenyl) maleimide, and N-aralkyl-substituted maleimide compounds such as N-benzylmaleimide. One or two or more of them can be used. For example, N-phenylmaleimide is used.

Further, examples of the unsaturated acid anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride and the like, and one or more of these can be used.

Examples of unsaturated carboxylic acid compounds include (meth) acrylic acid, silicic acid, crotonic acid, and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, crotonic acid, and citraconic acid, and unsaturated dicarboxylic acids. Examples thereof include alkyl esters, and one or more of them can be used.

Among these, the first monomer preferably contains, for example, at least styrenes. This is because styrenes are easy to carry out in the living room and can impart appropriate hydrophobicity and affinity to organic solvents. It is possible to impart hydrophobicity or affinity to an organic solvent to the first polymerized chain. By doing so, for example, when the polymer fine particles are produced by the dispersion polymerization method in a polar organic solvent, the first polymer tends to be present on the surface layer of the polymer fine particles, and the polymer fine particles are produced. Dispersion stability is improved.

Styrene is, for example, 20% by mass or more of the total mass of the first monomer (first monomer unit of the first polymerized chain) for polymerizing the first polymerized chain. This is because if the content is 20% by mass or more, the living polymerization is facilitated, and an appropriate hydrophobicity and an affinity for an organic solvent can be appropriately imparted. Further, for example, it is 30% by mass or more, and for example, 35% by mass or more, and for example, 40% by mass or more, and for example, 50% by mass or more, and for example, 60% by mass or more. Further, for example, it is 65% by mass or more, for example, 70% by mass or more, and for example, 75% by mass or more. Further, the styrenes are 100% by mass or less of the total mass, and are, for example, 95% by mass or less, and are, for example, 90% by mass or less, and are, for example, 85% by mass or less, and are, for example,. It is 80% by mass or less, and for example, 75% by mass or less. The range of the styrenes with respect to the total mass can be set by appropriately combining the above-mentioned lower limit and upper limit, and is, for example, 20% by mass or more and 95% by mass or less, and for example, 30% by mass or more and 75% by mass or more. And, for example, 35% by mass or more and 85% by mass or less.

The (meth) acrylonitrile compound, maleimide compound, acid anhydride and unsaturated carboxylic acid compound can be used alone, and it is preferable to use one or more of these four types in combination with styrenes. This is because all of these four types can maintain, regulate or impart the hydrophobicity or organic solvent affinity of the first polymerized chain. Among them, one or more of (meth) acrylonitrile compounds such as acrylonitrile, maleimide compounds such as N-phenylmaleimide and acid anhydrides are preferable, and combinations of styrene and acrylonitrile, styrene and N-phenylmaleimide and the like are preferable. Suitable. The unsaturated carboxylic acid compound is preferable in that the polarity of the first polymer can be easily changed.

When used in combination with styrenes, the total amount of these one or more first monomers other than styrenes is the first monomer for polymerizing the first polymerized chain (first). It is, for example, 20% by mass or more of the total mass of the first monomer unit of the polymerized chain). Further, for example, it is 25% by mass or more, and for example, 30% by mass or more, and for example, 35% by mass or more, and for example, 40% by mass or more, and for example, 50% by mass or more. Further, for example, it is 60% by mass or more. The (meth) acrylonitrile compound is 80% by mass or less of the total mass, and is, for example, 75% by mass or less, and is, for example, 70% by mass or less, and is, for example, 65% by mass or less. Further, for example, it is 60% by mass or less, for example, 55% by mass or less, and for example, 50% by mass or less. The total amount of these one or more first monomers other than styrenes can be set by appropriately combining the above lower limit and upper limit, and is, for example, 20% by mass or more and 65% by mass or less. Yes, and for example, it is 25% by mass or more and 50% by mass or less.

The first polymerized chain may be a polymerized chain containing only the first monomer described above, but if necessary, other vinyl-based monomers other than the above may be used as the first monomer. be able to. For example, known vinyl-based monomers such as (meth) acrylic acid ester such as alkyl (meth) acrylic acid can be used. It should be noted that these other monomers are, for example, 10% by mass or less, for example, 5% by mass or less, for example, 3% by mass or less, or, for example, the total mass of the monomers constituting the first polymerized chain. 1, 1% by mass or less, and for example, 0.5% by mass or less.

Further, the first polymer may include a polymerized chain as another block in addition to the above-mentioned first polymerized chain. Examples of the vinyl-based monomer constituting such a polymerized chain include (meth) acrylic acid, known (meth) acrylic acid alkyl esters, and known (meth) acrylic acid hydroxyalkyl esters. Such a vinyl-based monomer may be a second monomer described later. Such other polymerized chains may be added, for example, in another synthetic step after the formation of the first polymerized chain. By being provided so as to be directly linked to the living radical active unit described later and to be linked to the first polymerized chain, a part of the monomer common to the second monomer used for the polymer fine particles is previously provided. , Can be provided in the first polymer.

(Living radical polymerization active unit)
The first polymer can comprise a living radical polymerization active unit. Living radical polymerization generally consists of only a start reaction and a growth reaction in the polymerization step, and is not accompanied by a side reaction such as a chain transfer reaction or a stop reaction that inactivates the growth end, and the growth end is always during polymerization. It is said to be a polymerization reaction that maintains the growth activity (living radical polymerization activity) based on radical species. The living radical polymerization active unit is a growth active unit in living radical polymerization. The living radical polymerization active unit is a unit derived from a control agent of the living radical polymerization method.

Variously known for living radical polymerization from its reaction mechanism, the living radical polymerization active unit can be an active unit in living radical polymerization by an exchange chain mechanism or a bond-dissociation mechanism. With these living radical polymerizations, the first polymer having a narrow molecular weight distribution can be easily obtained, and in the dispersion polymerization of the polymer fine particles, the first polymer is soluble or dispersed in the polymerization solvent. Various monomers can be selected for their function as stabilizers.

Living radical polymerization by the exchange chain mechanism includes a reversible addition-cleavage chain transfer polymerization method (RAFT method), an iodine transfer polymerization method, a polymerization method using an organic tellurium compound (TERP method), and a polymerization method using an organic antimony compound (SBRP). Method), a polymerization method using an organic bismuth compound (BIRP method), and the like. Living radical polymerization by an exchange chain mechanism is preferable in that the average particle size of the polymer fine particles can be reduced. Among these, the RAFT method and the iodine transfer polymerization method are preferable in that the molecular weight distribution of the first polymer can be narrowed. Further, the RAFT method is preferably used.

Examples of the living radical polymerization by the bond-dissociation mechanism include the nitroxy radical method (NMP method). Living radical polymerization by a bond-dissociation mechanism is preferable in that the average particle size of the polymer fine particles can be reduced. Among these, the NMP method is preferable in that the molecular weight distribution of the first polymer can be narrowed.

The polymerization conditions by these various living radical polymerizations are well known to those skilled in the art, and if necessary, the synthesis of the first polymer by the RAFT method, the iodine transfer polymerization method and the NMP method will be exemplified. The living radical polymerization process includes various processes such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization. Considering this, in the production of the first polymer, for example, solution polymerization can be used.

The first polymer can be synthesized by the RAFT method using, for example, a control agent of the RAFT method. The RAFT method is a living radical polymerization method suitable for obtaining a first polymer having a molecular weight distribution of 2.0 or less. As the control agent (RAFT agent) for living radical polymerization in the RAFT method, a known RAFT agent can be used without particular limitation. For example, a dithioester compound, a xanthate compound, a trithiocarbonate compound, a dithiocarbamate compound and the like can be mentioned. The RAFT agent may be a monofunctional agent having one active site, or a bifunctional or more agent having two or more active sites. A RAFT agent having more than two functionalities has a polymer chain extending in more than two directions. From the viewpoint of producing polymer fine particles, it may be preferable to use a RAFT agent having bifunctionality or trifunctionality or higher.

The substituent in the RAFT agent can be appropriately determined in consideration of the first monomer and the second monomer. The amount of the RAFT agent used is appropriately adjusted according to the target Mn, and is, for example, 0.1 part by mass or more and 10 parts by mass or less, for example, with respect to 100 parts by mass of the first monomer. , 0.5 parts by mass or more and 5 parts by mass or less, for example, 1 part by mass or more and 4 parts by mass or less, and for example, 1 part by mass or more and 3 parts by mass or less can be used.

As the RAFT agent, various known RAFT agents such as a dithioester compound, a xanthate compound, a trithiocarbonate compound and a dithiocarbamate compound can be used. More specifically, for example, dibenzyltrithiocarbonate, dithiobenzoate / 2-cyano-2-propylbenzodithioate, 2-phenyl-2-propylbenzodithioate, trithiocarbonate, 2-cyano-2-propyl. Dodecyltrithiocarbonate, 2- (dodecylthiocarbonothio oilthio) -2-methylpropanoate, distyryltrithiocarbonate, dicumyltrithiocarbonate, dithiocarbamate, cyanomethyl N-methyl-N-phenyldithiocarbamate, etc. Be done.

As the radical polymerization initiator (radical generator) used in the polymerization by the RAFT method, known radical polymerization initiators such as azo compounds, organic peroxides and persulfates can be used, but they are handled for safety. An azo compound is preferable because it is easy to carry out and side reactions during radical polymerization are unlikely to occur. Specific examples of the above azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2'-azobis (4-methoxy-2, 4-Dimethylvaleronitrile), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile) and the like. As the radical polymerization initiator, one kind or two or more kinds can be used.

The proportion of such radical polymerization initiator used is not particularly limited, but the proportion of the radical polymerization initiator used is not particularly limited from the viewpoint of obtaining a polymer having a narrower molecular weight distribution, but from the viewpoint of obtaining a polymer having a narrower molecular weight distribution. With respect to 100 parts by mass of the total mass of the first monomer, for example, 0.005% by mass or more and 2% by mass or less, for example, 0.005% by mass or more and 1% by mass or less, and for example, 0.005. It can be used in an amount of% by mass or more and 0.5% by mass or less.

The RAFT method may be carried out in the presence of a chain transfer agent, if necessary. As the chain transfer agent, one or more known ones can be used.

Further, in the RAFT method, a known polymerization solvent can be used, and examples thereof include a nitrile solvent, an aromatic solvent, a ketone solvent, an ester solvent, an orthoester solvent, dimethylformamide, dimethyl sulfoxide, alcohol and water. Be done. Specific examples of the nitrile solvent include acetonitrile, isobutyronitrile, benzonitrile and the like. Specific examples of the aromatic solvent include benzene, toluene, xylene, anisole and the like. Specific examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone and the like. Specific examples of the ester solvent include methyl acetate, ethyl acetate, propyl acetate, butyl acetate and the like. Specific examples of the orthoester solvent include trimethyl orthoacetate, triethyl orthoate, triethyl orthoate (n-propyl), tri (isopropyl) orthoatete, trimethyl orthoacetate, triethyl orthoacetate, triethyl orthopropionate, ortho n-. Examples thereof include trimethyl butyrate and trimethyl orthoisobutyrate. Preferably, a nitrile solvent such as acetonitrile and / or an aromatic solvent such as anisole can be used.

The concentration of the first monomer when the first polymer is polymerized by living radical polymerization is not particularly limited with respect to the total mass of the polymerization solvent and the first monomer, but for example. It can be 10% by mass or more and 80% by mass or less, for example, 15% by mass or more and 70% by mass or less, 20% by mass or more and 70% by mass or less.

The reaction temperature during the polymerization reaction by the RAFT method is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 45 ° C. or higher and 90 ° C. or lower, and further preferably 50 ° C. or higher and 80 ° C. or lower. When the reaction temperature is 40 ° C. or higher, the polymerization reaction can proceed smoothly. On the other hand, when the reaction temperature is 100 ° C. or lower, side reactions can be suppressed and restrictions on the initiators and solvents that can be used are relaxed.

The first polymer can also be synthesized by the iodine transfer polymerization method using, for example, a control agent of the iodine transfer polymerization method. The control agent in the iodine transfer polymerization method is not particularly limited, and known control agents can be used, for example, methyl iodide, methylene iodide, iodoform, carbon tetraiodide, 1-phenylethyl iodide, benzyl. Iodine, methyl 2-iodoisobutyrate, ethyl 2-iodoisobutyrate, ethyl 2-iodo-2-phenylacetate, bis (2-iodo-2-phenylacetate) ethylene glycol, bis (2-iodoisobutyric acid) ethylene glycol, etc. Can be mentioned.

The amount of the iodine transfer control agent used is appropriately adjusted according to the target Mn, and is, for example, 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the first monomer. Further, for example, 0.5 parts by mass or more and 5 parts by mass or less, and for example, 1 part by mass or more and 4 parts by mass or less can be used. For example, 0.1 part by mass or more and 10 parts by mass or less, for example, 0.5 part by mass or more and 5 parts by mass or less, and for example, 1 part by mass or more and 4 parts by mass with respect to 100 parts by mass of the first monomer. It can be used below.

As the radical polymerization initiator (radical generator) used in the polymerization by the iodine transfer polymerization method, known radical polymerization of azo compounds, organic peroxides, persulfates and the like in the same manner and amount as in the RAFT method. Initiators can be used. The reaction temperature, the polymerization solvent, and the first monomer concentration in the iodine transfer polymerization method can be appropriately selected and applied from the same embodiments as in the RAFT method.

The first polymer can also be synthesized by the NMP method using, for example, a control agent of the NMP method. As the control agent in the NMP method, a known control agent can be used without particular limitation, for example, 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO), N-tert-. Butyl-N- [1-diethylphosphono- (2,2-dimethylpropyl)] nitroxide (DEPN), 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO), N- Examples thereof include tert-butyl-N- (1-tert-butyl-2-ethylsulfinyl) propyl-N-oxyl (BESN).

The amount of the control agent used by the NMP method is appropriately adjusted according to the target Mn, and is, for example, 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the first monomer. For example, 0.5 parts by mass or more and 5 parts by mass or less, and for example, 1 part by mass or more and 4 parts by mass or less can be used. For example, 0.1 part by mass or more and 10 parts by mass or less, for example, 0.5 part by mass or more and 5 parts by mass or less, and for example, 1 part by mass or more and 4 parts by mass with respect to 100 parts by mass of the first monomer. It can be used below.

The radical polymerization initiator (radical generator) used in the polymerization by the NMP method is a known radical polymerization initiator such as an azo compound, an organic peroxide, and a persulfate in the same manner and amount as in the RAFT method. Can be used. The reaction temperature, the polymerization solvent, and the first monomer concentration in the NMP method can be appropriately selected and applied from the same aspects as in the RAFT method.

By synthesizing the first polymer by a predetermined living radical polymerization, a first polymer having a first polymer chain containing the first monomer and a living polymerization active unit can be obtained. The first polymer may also include two or more first polymerized chains. For example, after performing living radical polymerization or the like using one or more first monomers of a certain composition, one or more first monomers of another composition are used. By carrying out living radical polymerization or the like, a first polymer having a first polymerization chain (block) having a unit derived from the first monomer having a different composition can be obtained.

According to the predetermined living radical polymerization, a first polymer in which the number average molecular weight (Mn) and the weight average molecular weight (Mw) are controlled can be obtained. The Mn of the first polymer is not particularly limited, but is, for example, 3,000 or more, for example, 5,000 or more, and for example, 7,000 or more, and for example, 8. It is 000 or more, and for example, 10,000 or more. Further, the Mn is 50,000 or less, for example, 30,000 or less, and for example, 25,000 or less, and for example, 20,000 or less, and for example, 15,000 or less. And, for example, 14,000 or less, and for example, 12,000 or less. The range of Mn can be set by appropriately combining the above-mentioned lower limit and upper limit, and is, for example, 5,000 or more and 25,000 or less, and for example, 10,000 or more and 25,000 or less, and also. For example, 10,000 or more and 15,000 or less, and for example, 10,000 or more and 14,000 or less.

The Mw of the first polymer is not particularly limited, but is, for example, 5,000 or more, for example, 7,000 or more, and for example, 9,000 or more, and for example, 10. It is 000 or more, and is, for example, 13,000 or more, and is, for example, 15,000 or more. Further, the Mw is 60,000 or less, for example, 55,000 or less, and for example, 50,000 or less, and for example, 45,000 or less, and for example, 40,000 or less. And, for example, 36,000 or less, and for example, 35,000 or less, and for example, 30,000 or less, and for example, 25,000 or less. The range of Mw can be set by appropriately combining the above-mentioned lower limit and upper limit, and is, for example, 1,000 or more and 40,000 or less, and for example, 10,000 or more and 35,000 or less. For example, it is 10,000 or more and 30,000 or less, and for example, 15,000 or more and 25,000 or less.

Both Mw and Mn of the first polymer can be measured by gel permeation chromatography using polystyrene as a standard substance. As for the details of the chromatography conditions, the conditions disclosed in the subsequent examples can be adopted.

The molecular weight distribution (Mw / Mn) of the first polymer is not particularly limited, but is, for example, 2.5 or less, for example, 2.4 or less, and for example, 2.3 or less. Yes, for example 2.0 or less, and for example 1.6 or less, and for example 1.5 or less, and for example 1.4 or less, and for example 1.3 or less. is there. Further, the molecular weight distribution is, for example, 1.1 or more, for example, 1.2 or more, and for example, 1.3 or more, and for example, 1.4 or more, and for example, 1.5 or more. Is. The range of the molecular weight distribution can be set by appropriately combining the above-mentioned lower limit and upper limit. For example, 1.1 or more and 2.5 or less, for example, 1.1 or more and 2.4 or less, and for example, 1 It can be 1. or more and 2.3 or less, and for example, 1.1 or more and 2.0 or less.

The narrower the molecular weight distribution, the smaller the average particle size of the obtained polymer fine particles tends to be. It is preferable that the molecular weight distribution is 2.4 or less in order to obtain polymer fine particles having an average particle size of 0.2 μm or less, and 1.7 in order to obtain polymer fine particles having a smaller average particle size. The following is preferable, more preferably 1.6 or less, and even more preferably 1.4 or less.

The first polymer can include a first polymer chain and a living polymerization active unit, but typically, when a monofunctional control agent is used, the living polymerization active unit is the first. When a control agent having bifunctionality or higher is used, it is branched in two or more directions with the living polymerization active unit as a base point, and each of them is provided with a first polymerized chain. .. In any of the embodiments, when another polymerized chain is provided, the other polymerized chain is directly bonded to the living polymerization active unit, and the first polymerization is carried out more distally to the living polymerization active unit. The first polymerized chain is bonded to the distal end of the other polymerized chain so that the chain is provided.

(Production of Polymer Fine Particles) This method can produce polymer fine particles by dispersion-polymerizing one kind or two or more kinds of second monomers in the presence of the first polymer. In this method, the first polymer can be used as a starting point for the polymerization of the second monomer in the production of the polymer fine particles, and can also be used as a dispersion stabilizer in the polymerization solvent of the polymer fine particles. By doing so, the polymerization stability, that is, the aggregation of the polymer fine particles during the polymerization step is suppressed, the generation of coarse agglomerated particles is suppressed, the average particle size is small, and the particle size distribution is narrow. Can be obtained.

(Second vinyl-based monomer) The second vinyl-based monomer is not particularly limited, and may be appropriately selected from known vinyl-based monomers depending on the use of the polymer fine particles and the like. Can be done. For example, the first polymer effectively exerts its function as a dispersion stabilizer so that it is present on the surface layer side of the polymer fine particles, and the second polymer chain is present on the core side as the main component of the polymer fine particles. The second monomer can be a vinyl-based monomer having a hydrophilic group. Considering this viewpoint, examples of the second monomer include a carboxyl group-containing vinyl-based monomer and a hydroxy group-containing vinyl-based monomer.

Examples of the carboxy group-containing vinyl-based monomer include unsaturated carboxylic acids such as (meth) acrylic acid and crotonic acid, unsaturated dicarboxylic acids such as itaconic acid, maleic acid, and fumaric acid, and unsaturated dicarboxylic acids. Examples thereof include monoalkyl esters. Of these, (meth) acrylic acid is preferable.

(Meta) acrylic acid may be in the form of a salt. Here, the (meth) acrylic acid (salt) includes (meth) acrylic acid and (meth) acrylic acid salt. The salt in the (meth) acrylate is an alkali metal salt, an alkaline earth metal salt, an ammonium salt or an organic amine salt. Specifically, alkali metal salts such as sodium salt, lithium salt, potassium salt, rubidium salt, and cesium salt; alkaline earth metal salts such as magnesium salt, calcium salt, strontium salt, and barium salt; Examples include alkanolamine salts such as monoethanolamine salt, diethanolamine salt and triethanolamine salt, alkylamine salts such as monoethylamine salt, diethylamine salt and triethylamine salt, and organic amine salts such as polyamine such as ethylenediamine salt and triethylenediamine salt. Be done.

Examples of the hydroxy group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. , 3-Hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and mono (meth) acrylic acid esters of polyalkylene glycols such as polyethylene glycol and polypropylene glycol. These compounds may be used alone or in combination of two or more.

Such a second monomer can be used alone or in combination of two or more. The carboxyl group-containing vinyl-based monomer can be, for example, 40% by mass or more, and can be, for example, 50% by mass or more, based on the total mass of the second monomer. It can be 60% by mass or more, for example, 70% by mass or more, and can be, for example, 80% by mass or more, and can be, for example, 90% by mass or more. For example, it can be 95% by mass or more, and can be, for example, 100% by mass. The range of use of the carboxyl group-containing vinyl-based monomer with respect to the total mass of the second monomer can be set by appropriately combining the above lower and upper limits, and is, for example, 60% by mass or more and 100% by mass or less. Further, for example, it is 80% by mass or more and 100% by mass or less, and for example, 90% by mass or more and 100% by mass or less.

Further, the hydroxy group-containing vinyl-based monomer is, for example, 5% by mass or more, for example, 10% by mass or more, and for example, 20% by mass or more, based on the total mass of the second monomer. Yes, for example, 30% by mass or more, and for example, 40% by mass or more. Further, it is 50% by mass or less, and is, for example, 40% by mass or less, and is, for example, 30% by mass or less, and is, for example, 20% by mass or less, and is, for example, 10% by mass or less. For example, it is 5% by mass or less. The range of use of the hydroxy group-containing vinyl-based monomer with respect to the total mass of the second monomer can be set by appropriately combining the above lower and upper limits, and is, for example, 0% by mass or more and 40% by mass or less. Further, for example, it is 0% by mass or more and 20% by mass or less, and for example, 0% by mass or more and 10% by mass or less.

As the second monomer, other vinyl-based monomers can be included as long as the intended function of the second polymer chain in the polymer fine particles is not impaired. The vinyl-based monomer is not particularly limited, and examples thereof include (meth) acrylic acid alkyl ester and (meth) acrylic acid alkoxyalkyl ester. Such a second monomer is, for example, 20% by mass or less, for example, 10% by mass or less, and for example, 5% by mass or less, or, for example, 3% by mass, based on the total mass of the second monomer. % Or less, for example, 1% by mass or less can be contained.

Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, isopropyl (meth) acrylic acid, n-propyl (meth) acrylic acid, n-butyl (meth) acrylic acid, and ( Isobutyl acrylate, tert-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, (meth) Linear or branched alkyl ester compounds of (meth) acrylic acid such as n-nonyl acrylate, isononyl (meth) acrylate, decyl (meth) acrylate and dodecyl (meth) acrylate; cyclohexyl (meth) acrylate. , (Meta) methylcyclohexyl acrylate, (meth) tert-butylcyclohexyl acrylate, (meth) cyclododecyl acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, dicyclopentenyl (meth) acrylate, Examples thereof include aliphatic cyclic ester compounds of (meth) acrylic acid such as dicyclopentanyl (meth) acrylic acid.

Examples of the (meth) acrylate alkoxyalkyl ester include methoxymethyl (meth) acrylate, ethoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, and (meth). 2-propoxyethyl acrylate, 2-butoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 3-propoxypropyl (meth) acrylate, (meth) Examples thereof include 3-butoxypropyl acrylate, 3-methoxybutyl (meth) acrylate, 3-ethoxybutyl (meth) acrylate, 3-propoxybutyl (meth) acrylate, and 3-butoxybutyl (meth) acrylate. ..

In the process of producing the polymer fine particles, a crosslinked structure can be introduced into the second polymerized chain.

The method for introducing the crosslinked structure is not particularly limited, and examples thereof include the following methods.
1) Copolymerization of crosslinkable monomers 2) Utilizing chain transfer to polymer chains during radical polymerization 3) After synthesizing a polymer having a reactive functional group, post-crosslinking is performed by adding a crosslinking agent as necessary. Among these, the method by copolymerization of crosslinkable monomers is preferable because the operation is simple and the degree of crosslinking can be easily controlled.

Examples of the crosslinkable monomer include a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups, a monomer having a self-crosslinkable crosslinkable functional group such as a hydrolyzable silyl group, and the like. Can be mentioned. The polyfunctional polymerizable monomer is a compound having two or more polymerizable functional groups such as a (meth) acryloyl group and an alkenyl group in the molecule, and is a polyfunctional (meth) acrylate compound, a polyfunctional alkenyl compound, ( Meta) Examples thereof include compounds having both an acryloyl group and an alkenyl group. These compounds may be used alone or in combination of two or more. Among these, a polyfunctional alkenyl compound is preferable because a uniform crosslinked structure can be easily obtained, and a polyfunctional allyl ether compound having a plurality of allyl ether groups in the molecule is particularly preferable.

Examples of the polyfunctional (meth) acrylate compound include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and polypropylene glycol di (meth) acrylate. Di (meth) acrylates of dihydric alcohols such as meta) acrylate; trimethylol propantri (meth) acrylate, tri (meth) acrylate of trimethyl propanethylene oxide modified product, glycerin tri (meth) acrylate, pentaerythritol tri (meth) Tri (meth) acrylates of trivalent or higher polyhydric alcohols such as meta) acrylates and pentaerythritol tetra (meth) acrylates, poly (meth) acrylates such as tetra (meth) acrylates; Bisamides and the like can be mentioned.

Examples of the polyfunctional alkenyl compound include polyfunctional allyl ether compounds such as trimethylolpropanediallyl ether, trimethylolpropanetriallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, tetraallyloxyethane, and polyallyl saccharose; Polyfunctional allyl compound; Polyfunctional vinyl compounds such as divinylbenzene and the like can be mentioned.

Compounds having both (meth) acryloyl group and alkenyl group include allyl (meth) acrylate, isopropenyl (meth) acrylate, butenyl (meth) acrylate, pentenyl (meth) acrylate, and (meth) acrylate. 2- (2-Vinyloxyethoxy) ethyl and the like can be mentioned.

Specific examples of the monomer having a self-crosslinkable crosslinkable functional group include a hydrolyzable silyl group-containing vinyl monomer, N-methylol (meth) acrylamide, N-methoxyalkyl (meth) acrylamide and the like. Can be mentioned. These compounds can be used alone or in combination of two or more.

The hydrolyzable silyl group-containing vinyl monomer is not particularly limited as long as it is a vinyl monomer having at least one hydrolyzable silyl group. For example, vinyl silanes such as vinyl trimethoxysilane, vinyl triethoxysilane, vinyl methyl dimethoxysilane, vinyl dimethyl methoxysilanen; silyl such as trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, methyldimethoxysilylpropyl acrylate and the like. Group-containing acrylic acid esters; silyl group-containing methacrylate esters such as trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, dimethylmethoxysilylpropyl methacrylate; trimethoxysilylpropyl vinyl ether and the like. Cyril group-containing vinyl ethers; silyl group-containing vinyl esters such as trimethoxysilyl undecanoate vinyl and the like can be mentioned.

The amount of the crosslinkable monomer used is, for example, 0.1% by mass or more and 5% by mass or less with respect to the total mass of the monomers other than the crosslinkable monomer (non-crosslinkable monomer). For example, it is 0.5% by mass or more and 3% by mass or less. The amount of the crosslinkable monomer used is, for example, 0.01 mol% or more and 2 mol% or less, and for example, 0.03 mol% or more, based on the total molar amount of the non-crosslinkable monomer. It is 2 mol% or less, and for example, 0.5 mol% or more and 1 mol% or less.

In the production of the polymer fine particles, since the first polymer has a living polymerization activity unit, by adding an appropriate radical polymerization initiator (radical generator), the second monomer has a living polymerization activity. Polymerized with respect to the unit. The radical polymerization initiator can be appropriately selected from the various aspects described for the RAFT agent. The proportion of the radical polymerization initiator used is not particularly limited, but from the viewpoint of obtaining a polymer having a narrower molecular weight distribution, for example, 0.01% by mass or more is 5 with respect to 100 parts by mass of the total mass of the second monomer. By mass% or less, for example, 0.02% by mass or more and 3% by mass or less, and for example, 0.03% by mass or more and 3% by mass or less can be used.

By adopting the dispersion polymerization method for the production of the polymer fine particles, the polymer fine particles having a small average particle size can be easily obtained. The polymerization solvent used in the production of the polymer fine particles can be appropriately set according to the polymerization method to be adopted and the types of the first monomer, the second monomer and the like. When the dispersion polymerization method is adopted, for example, various solvents used in the synthesis of the first polymer can be appropriately used. For example, a nitrile solvent such as acetonitrile can be used.

By using the polymerization solvent at the time of synthesizing the first polymer, the first polymer can be dissolved, and the first polymer chain and the control agent for living radical polymerization can be easily dissolved. , The first polymerized chain is present on the surface layer side of the polymer fine particles, and the second polymerized chain side made of acrylic acid or the like as an extension end can be polymerized while being organized so as to be present inside the polymer fine particles. it can. Therefore, it becomes easy to form a fine particle structure having excellent dispersion stability.

Further, in consideration of dispersion polymerization, the polymerization solvent at the time of producing the polymer fine particles needs to be a poor solvent in which the second monomer and the like are dissolved but the polymer fine particles containing the polymer chains are not dissolved. Can be determined in consideration of.

For example, as the polymerization solvent at the time of producing the polymer fine particles, a nitrile solvent such as acetonitrile, an alcohol solvent such as methanol and t-butyl alcohol, a ketone solvent such as acetone, and a furan solvent such as tetrahydrofuran ether such as tetrahydrofuran. In addition to the system solvent, benzene, ethyl acetate, dichloroethane, n-hexane, cyclohexane, n-heptane and the like can be mentioned, and one of these can be used alone or in combination of two or more. Further, it can be used as a mixed solvent of such a solvent and a highly polar solvent such as water. When the polymerization solvent of the polymer fine particles contains a highly polar solvent such as water, the (meth) acrylic acid can be rapidly neutralized in the polymerization step. The amount of the highly polar solvent used is preferably 0.05 to 10.0% by mass, more preferably 0.1 to 5.0% by mass, and further preferably 0.1 to 1 by mass with respect to the total mass of the medium. It is 0.0% by mass. When the proportion of the highly polar solvent is 0.05% by mass or more, the effect on the neutralization reaction is recognized, and when it is 10.0% by mass or less, no adverse effect on the polymerization reaction is observed.

The concentration of the second monomer in the polymerization solvent is not particularly limited, but can be appropriately set, but can be, for example, 5% by mass or more and 30% by mass or less, and for example, 10% by mass or more. It can be 20% by mass or less.

The reaction temperature during the polymerization reaction during the production of the polymer fine particles is not particularly limited, but is, for example, 40 ° C. or higher and 100 ° C. or lower. Further, for example, it is 45 ° C. or higher and 90 ° C. or lower, and for example, 50 ° C. or higher and 80 ° C. or lower. When the reaction temperature is 40 ° C. or higher, the polymerization reaction can proceed smoothly. On the other hand, when the reaction temperature is 100 ° C. or lower, side reactions can be suppressed and restrictions on the initiators and solvents that can be used are relaxed.

The second monomer will be described in detail later, but in the presence of the first polymer, when the second monomer is polymerized to produce polymer fine particles, the first polymer is dispersed. In order to function as a stabilizer, for example, the first polymer can be used in an amount of 0.3 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the total mass of the second monomer. By using it in such a range, it is possible to produce polymer fine particles mainly containing the second monomer while allowing the first polymer to function as a dispersion stabilizer. Further, when the amount of the first polymer is less than 0.3 parts by mass, it is difficult to obtain a sufficient dispersion stabilizing effect, and the average particle size of the polymer fine particles tends to exceed 0.2 μm, even if it exceeds 50 parts by mass. This is because it is difficult to improve the functionality as a dispersion stabilizer, and the effect of reducing the average particle size of the polymer fine particles is also reduced.

The first polymer can be used with respect to 100 parts by mass of the total mass of the second monomer, for example, 0.5 parts by mass or more, and for example, 1 part by mass or more. Further, the first polymer can be used, for example, 50 parts by mass or less, for example, 40 parts by mass or less, for example, 30 parts by mass or less, and for example, 20 parts by mass or less. The range of the amount of the first polymer used with respect to 100 parts by mass of the total mass of the second monomer can be set by appropriately combining the above upper limit and lower limit, and is, for example, 0.3 parts by mass or more and 30 parts by mass or less. Yes, for example, 0.3 parts by mass or more and 20 parts by mass or less, for example, 0.5 parts by mass or more and 20 parts by mass or less, and for example, 1 part by mass or more and 20 parts by mass or less.

Polymer fine particles can be produced by the above method. According to this method, polymer fine particles having an average particle size of 0.2 μm or less can be easily obtained. In addition, since it is excellent in polymerization stability, it is possible to suppress the generation of agglomerates during the polymerization step and suppress the formation of coarse particles. In the present specification, the average particle size of the polymer fine particles is obtained by measuring the particle size of the polymer fine particles observed under a microscope using image analysis software or the like and obtaining the average value thereof. be able to. The average value of the particle sizes of 400 particles in the image observed by the electrolytic radiation scanning electron microscope can be used as the average particle size of the fine particles. More specifically, the following method can be adopted. Using an electric field radiation scanning electron microscope (FE-SEM, JSM-6330F manufactured by JEOL Ltd.) or a microscope with the same resolution as the electron microscope, a photographed image in which 50 to 100 particles can be observed on one sheet is captured. For the obtained images, use the image analysis software "WinROOF" manufactured by Mitani Shoji Co., Ltd. or software that can count the number of particles and particle size with the same accuracy and accuracy as the software. The total number of particles is 200, and the particle diameter (diameter equivalent to a circle) is measured for 200 particles. Further, this operation is performed to measure the particle size of 200 particles in the same manner for another captured image. The average value of the total particle diameters of 400 particles can be used as the average particle diameter. Further, the number of coarse particles can be obtained by counting the number of coarse particles in 100 particles, using the particles having twice or more the average particle diameter thus obtained as coarse particles.

In particular, the residual agglomerates in the polymerization stability test disclosed in the Examples are, for example, 200 ppm or less, for example 150 ppm or less, and for example 100 ppm or less, for example 60 ppm or less, and for example 40 ppm or less, and for example. Polymer fine particles of 20 ppm or less, for example, 10 ppm or less can be obtained.

Further, it is possible to obtain polymer fine particles in which the number of coarse particles per 100 particles disclosed in the examples is 2 or less, for example, 1 or less.

As described above, the first polymer disclosed in the present specification is useful as a dispersion stabilizer for the production of polymer fine particles. By producing the polymer fine particles using the first polymer as a dispersion stabilizer, a starting point for the polymerization of the polymer fine particles that can be dissolved in the polymerization solvent with a uniform number average molecular weight is provided, and in the polymerization solvent. Promotes self-assembly of the first polymerized chain and the second polymerized chain, which are suitable for particle nuclei and particle growth by the second monomer, and maintains good polymerization stability of polymer fine particles having a small average particle size. However, it can be easily manufactured.

Hereinafter, examples as specific examples will be described in order to explain the disclosure of the present specification more concretely. The following examples are intended to illustrate the disclosure herein and are not intended to limit its scope. In the following examples, unless otherwise specified,% represents mass% and parts represent mass parts.

(Method for measuring the molecular weight of polymer)
In the following examples, the molecular weight of the polymer was measured by gel permeation chromatography (GPC). That is, a polystyrene-equivalent number average molecular weight (Mn) and a weight average molecular weight (Mw) were obtained by THF-based GPC. Moreover, the molecular weight distribution (Mw / Mn) was calculated from the obtained values. The GPC was performed under the following conditions.

Column: Tosoh TSKgel Super Multipore HZ-M x 4 Solvent: Tetrahydrofuran Temperature: 40 ° C. Detector: RI flow velocity: 600 μL / min

(Synthesis of polymer with living polymerization activity)
(Polymer 1: P (St / PhMI))
2.0 parts of RAFT agent (dibenzyltrithiocarbonate: hereinafter also referred to as "DBTTC"), 2,2'-azobis (2-) in a 1 L flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube. Methylbutyronitrile) (manufactured by Nippon Finechem Co., Ltd., trade name "ABN-E": hereinafter also referred to as "ABN-E") 0.014 parts, styrene (hereinafter also referred to as "St") 38 parts, N -62 parts of phenylmaleimide (hereinafter, also referred to as "PhMI") and 222 parts of acetonitrile were charged, sufficiently degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 70 ° C. After 4 hours, the reaction was stopped by cooling to room temperature. The above polymerization solution was reprecipitated and purified from methanol / water = 90/10 (vоl%) and vacuum dried to obtain a polymer 1. As a result of analysis by gas chromatography, the reaction rates of the obtained polymer 1 were St75% and PhMI75%. The molecular weight of the polymer 1 was Mn10,200, Mw15,300, and Mw / Mn was 1.51. In addition, St and PhMI correspond to the first monomer. The composition, molecular weight distribution, etc. of the polymer are shown in Table 1 (the same applies hereinafter).

(Polymer 2: P (St / AN))
RAFT agent (DBTTC) 2.0 parts, ABN-E 0.41 parts, St75 parts, acrylonitrile (hereinafter, also referred to as "AN") 25 in a 1 L flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube. 67 parts and 67 parts of anisole were charged, sufficiently degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 80 ° C. After 4 hours, the reaction was stopped by cooling to room temperature. The polymer solution was reprecipitated and purified from methanol / water = 90/10 (vоl%) and vacuum dried to obtain a polymer 2. As a result of analysis by gas chromatography, the reaction rates of the polymer 2 were St73% and AN72%. The molecular weight of the polymer 2 was Mn11,900, Mw15,500, and Mw / Mn was 1.30. In addition, St and AN correspond to the first monomer.

(Polymer 3: P (St / maleic anhydride))
A 1 L flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube is charged with 2.0 parts of RAFT agent (DBTTC), 0.070 parts of ABN-E, 52 parts of St, 48 parts of maleic anhydride, and 207 parts of acetonitrile. , Nitrogen bubbling was sufficiently degassed, and polymerization was started in a constant temperature bath at 70 ° C. 4 hours later
The reaction was stopped by cooling to room temperature. The above polymerization solution was reprecipitated and purified from toluene and vacuum dried to obtain a polymer 3. As a result of analysis by gas chromatography, the reaction rate of the obtained polymer 3 was St 71% and maleic anhydride 71%. The molecular weight of the polymer 3 was Mn13,800, Mw22,200, and Mw / Mn was 1.61. In addition, St and maleic anhydride correspond to the first monomer.

(Polymer 4: P (St / PhMI))
3.24 parts of 1-phenylethyl iodide (1-PEI), 0.019 parts of ABN-E, 0.01 parts of St, 62 parts of PhMI, and acetonitrile in a 1 L flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube. 221 parts were charged, sufficiently degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 70 ° C. After 4 hours, the reaction was stopped by cooling to room temperature. The polymer solution was reprecipitated and purified from methanol / water = 90/10 (vоl%) and vacuum dried to obtain a polymer 4. As a result of analysis by gas chromatography, the reaction rates of the polymer 4 were St74% and PhMI74%. The molecular weight of the polymer 4 was Mn13,100, Mw31,100, and Mw / Mn was 2.37. In addition, St and PhMI correspond to the first monomer.

(Polymer 5: P (St / AN) -b-PAA)
70 parts of polymer 2, 0.019 parts of ABN-E, 100 parts of acrylic acid (hereinafter, also referred to as "AA") and 255 parts of acetonitrile in a 1 L flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube. The part was charged, sufficiently degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 70 ° C. After 4 hours, the reaction was stopped by cooling to room temperature. The above polymerization solution was reprecipitated and purified from hexane and vacuum dried to obtain a polymer 5. As a result of analysis by gas chromatography, the reaction rate of AA was 74%. The molecular weight of the polymer 5 after methyl esterification was Mn24,800, Mw35,500, and Mw / Mn was 1.43. In addition, St and AN correspond to the first monomer.

(Synthesis of polymer having no living polymerization activity)
(Polymer 1': P (St / AN))
A 1 L flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube is charged with 1.0 part of RAFT agent (DBTTC), 0.38 part of ABN-E, 75 parts of St, 25 parts of AN, and 66 parts of anisole, and nitrogen bubbling. Was sufficiently degassed, and polymerization was started in a constant temperature bath at 80 ° C. After 4 hours, a part of the polymerization solution was collected and the obtained monomer reaction rate measured by gas chromatography was St73% and AN72%. Next, after cooling the reaction solution to 40 ° C., 4.14 parts of n-propylamine sufficiently degassed by nitrogen bubbling was charged, and a decomposition reaction of RAFT groups was carried out. After another 4 hours, 9.04 parts of methyl acrylate (MA) sufficiently degassed by nitrogen bubbling was charged, and the terminal inactivation reaction was carried out at 40 ° C. for 4 hours. The above polymerization solution was reprecipitated and purified from methanol / water = 90/10 (vоl%) and vacuum dried to obtain a polymer 1'. The molecular weight of the polymer 1'was Mn11,200, Mw15,100, and Mw / Mn was 1.35.

Here, as a result of calculating the decomposition rate of the RAFT group (thiocarbonylthio group) for the polymer 1'according to the following measurement method, it was 100%, so that the polymer 1'has no living polymerization activity. It was confirmed.

<Measurement method of decomposition rate of thiocarbonylthio group>
After dissolving 1'5 g of the polymer in 15 g of acetone, it was cast on a polypropylene disposable tray (100 mm × 70 mm × 13 mm, manufactured by AS ONE), air-dried at room temperature for 16 hours, and then dried at 70 ° C., 4.5 Torr for 16 hours. A sheet-shaped sample was prepared by allowing the sample to be prepared. Next, using the obtained sheet-shaped sample, fluorescent X-ray analysis was performed under the following measurement conditions to quantify the sulfur content (%) in the sample. Using the obtained sulfur content, the decomposition rate (%) of the thiocarbonylthio group by n-propylamine was calculated according to the following formula. The results are shown in Table 1.
Decomposition rate of thiocarbonylthio groups = {(BA) / B} × {N / (N-1)} × 100
B: Sulfur content (%) in the sample before reaction with n-propylamine
A: Sulfur content (%) in the sample after the reaction with n-propylamine
N: Number of sulfur atoms in one thiocarbonylthio group ○ Measuring conditions Measuring equipment: ZSX PrimusII X-ray manufactured by Rigaku Co., Ltd .: Rh (50 kV, 50 mA)
Measurement element: C to U (C, N, O, S are measured at a fixed angle)
Analytical diameter: 20 mm
Analysis: Semi-quantitative analysis of detected elements by fundamental parameter method (FP method)

St: Styrene PhMI: N-Phenylmaleimide AN: Acrylonitrile AA: Acrylic acid DBTTC: Dibenzyltrithiocarbonate 1-PEI: 1-Phenylethyliodide ABN-E: 2,2-azobis (2-methylbutyronitrile) , Made by Japan Finechem, product name "ABN-E"
MA: Methyl acrylate

<Production example of polymer fine particles>
(Example 1)
In Example 1, polymer fine particles were produced using the polymer 1. A reactor equipped with a stirring blade, a thermometer, a reflux condenser and a nitrogen introduction tube was used for the polymerization. 567 parts of acetonitrile, 2.20 parts of ion-exchanged water, 100.0 parts of AA, 0.90 parts of trimethylolpropane diallyl ether (manufactured by Daiso, trade name "Neoallyl T-20"), 1 part of polymer 1 in the reactor. 0.0 parts and 1.0 mol% of triethylamine with respect to the above AA were charged. After sufficiently replacing the inside of the reactor with nitrogen, the inside temperature was raised to 55 ° C. by heating. After confirming that the internal temperature was stable at 55 ° C., 2,2'-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-65") 0 as a polymerization initiator. When .040 parts were added, white turbidity was observed in the reaction solution, and this point was set as the polymerization initiation point. The polymerization reaction was continued while maintaining the internal temperature at 55 ° C. by adjusting the external temperature (water bath temperature), and the internal temperature was raised to 65 ° C. when 6 hours had passed from the polymerization initiation point. The internal temperature was maintained at 65 ° C., and 12 hours after the reaction start point, the reaction rate of AA was 97%, and a reaction solution of a slurry-like polymer in which particles were dispersed in a medium was obtained. The obtained reaction solution was centrifuged to settle the polymer fine particles, and then the supernatant was removed. Then, after redispersing the precipitate in acetonitrile having the same mass as the polymerization reaction solution, the washing operation of precipitating the polymer fine particles by centrifugation to remove the supernatant was repeated twice. The precipitate was collected and dried under reduced pressure at 80 ° C. for 3 hours to remove volatile matter, thereby obtaining the polymer fine particles described in Example 1.

(Examples 2 to 12, Comparative Examples 1 and 2)
The same operation as in Example 1 was carried out except that the preparation was changed as shown in Table 2, and polymer fine particles were obtained.

<Evaluation of polymerization stability>
The reaction solution of the slurry-like polymer obtained in each Example and Comparative Example was filtered through a 200-mesh polynet (opening: 114 μm), and the mass of the agglomerates remaining on the polynet after drying was obtained. Was measured, and the amount of agglomerates with respect to the total amount charged was measured. The results are shown in Table 2.

<Measurement of average particle size and number of coarse particles>
For the polymer fine particles obtained in each Example and Comparative Example, 50 to 100 particles were formed per particle using an electric field radiation scanning electron microscope (FE-SEM, JSM-6330F manufactured by JEOL Ltd.). We acquired multiple observable captured images, and used the image analysis software "WinROOF" manufactured by Mitani Shoji Co., Ltd. to count the obtained images until the total number of particles reached 200, and about 200 particles were particles. The diameter (diameter equivalent to a circle) was measured. In this operation, the particle size of 200 particles was measured in the same manner for another captured image. The average value of the total particle diameters of 400 particles was taken as the average particle diameter. Further, particles having twice or more the average particle diameter thus obtained were regarded as coarse particles, and the number of coarse particles in 100 particles was counted. The results are shown in Table 2.

AA: HEA acrylate: 2-Hydroxyethyl acrylate T-20: Trimethylolpropane diallyl ether, manufactured by Daiso Corporation, trade name "Neoallyl T-20"
TEA: Triethylamine AcN: Acetonitrile V-65: 2,2'-azobis (2,4-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-65"

As shown in Table 2, in Examples 1 to 12, polymers 1 to 3 and 5 having active units in living radical polymerization by an exchange chain mechanism obtained by using RAFT polymerization, and iodine transfer polymerization were used. By using the obtained polymer 4 having an active unit in living radical polymerization by a bond-dissociation mechanism, the polymerization stability of the polymer fine particles at the time of polymerization was excellent, and as a result, the number of coarse particles was small. The average particle size of the polymer fine particles was 0.20 μm or less. On the other hand, Comparative Example 1 in which such a dispersion stabilizer was not used and Comparative Example 2 in which a polymer having no living polymerization activity was used as the dispersion stabilizer were inferior in polymerization stability and therefore had a large number of coarse particles. The average particle size of the obtained polymer fine particles was more than 0.50 μm.

Further, from Table 2, it was found that the narrower the molecular weight distribution of the polymers 1 to 5 (dispersion stabilizer) having a predetermined living radical polymerization active unit, the smaller the average particle size of the polymer fine particles. Further, from the results of Examples 2 to 6, it was found that the average particle size of the polymer fine particles became smaller when the amount of the polymer (dispersion stabilizer) having a living polymerization active unit was large.

Claims (12)

1. In the presence of a polymer chain of one or more first vinyl-based monomers and a first polymer having a living radical polymerization active unit, one or more second vinyl-based monomers Is provided with a step of producing polymer fine particles by polymerizing by dispersion polymerization using living radical polymerization based on the living radical polymerization activity.
   The method, wherein the living radical polymerization active unit is an active unit in living radical polymerization by an exchange chain mechanism or a bond-dissociation mechanism.
2. The method according to claim 1, wherein the living radical polymerization active unit is living radical polymerization by the exchange chain mechanism.
3. The method according to claim 1 or 2, wherein the living radical polymerization active unit is an active unit in living radical polymerization by a reversible addition-cracking chain transfer polymerization method or an iodine transfer polymerization method.
4. The method according to any one of claims 1 to 3, wherein the molecular weight distribution of the first polymer is 2.0 or less.
5. In the step of producing the polymer fine particles, 0.3 parts by mass or more and 50 parts by mass or less of the first polymer is used with respect to 100 parts by mass of the second vinyl-based monomer of one or more kinds. The method according to any one of claims 1 to 4.
6. In the step of producing the polymer fine particles, 0.3 parts by mass or more and 20 parts by mass or less of the first polymer is used with respect to 100 parts by mass of the second vinyl-based monomer of one or more kinds. The method according to claim 5.
7. The second vinyl-based monomer of one kind or two or more kinds contains acrylic acid or a salt thereof, and the polymerization solvent in the step of producing the polymer fine particles contains acetonitrile, according to any one of claims 1 to 6. The method described.
8. The one or more first vinyl-based monomers are styrenes selected from the group consisting of styrenes, (meth) acrylonitrile compounds, maleimide compounds, unsaturated acid anhydrides and unsaturated carboxylic acid compounds. The method according to claim 7, wherein there are two or more kinds including.
9. The method according to any one of claims 1 to 8, wherein the one or more kinds of second vinyl-based monomers contain acrylic acid of 50% by mass or more and 100% by mass or less of the total mass thereof. ..
10. The method according to claim 9, wherein the one type or two or more types of the first vinyl-based monomer contains styrenes in an amount of 20% by mass or more based on the total mass thereof.
11. The one or more first vinyl-based monomers contain 20% by mass or more of styrenes based on the total mass of the first vinyl-based monomer, and the one or more second vinyl-based monomers contain 20% by mass or more of the total mass. Contains acrylic acid or a salt thereof in an amount of 50% by mass or more and 100% by mass or less of the total mass.
    The first polymer comprises a living radical polymerization active unit by reversible addition-cleavage chain transfer polymerization.
    The method according to claim 1, wherein the first polymer is used in an amount of 0.3 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the one or more second vinyl-based monomers.
12. Used for producing polymer fine particles, which comprises a polymer comprising a polymer chain of one or more kinds of first vinyl-based monomers and a living polymerization active unit provided in at least a part of the polymer chain. Dispersion stabilizer for.