JP5287142B2 - Method for producing polymer fine particles - Google Patents

Description

  The present invention relates to a method for producing polymer fine particles.

  Polymer fine particles are widely used in the fields of various spacers used in liquid crystals and the like, slipperiness modifiers for various films, fillers for liquid chromatography, ion exchange resins, plastic modifiers, and the like.

  Conventionally, polymer fine particles have been produced by emulsion polymerization, suspension polymerization, seed polymerization, dispersion polymerization, and polymer precipitation. Among these, as a means for improving monodispersity, for example, obtained by suspension polymerization or the like. The obtained styrene copolymer fine particles are sieved and then subjected to a swelling process to obtain relatively uniform and large particles (for example, refer to Patent Document 1), the method of simply obtaining fine particles by sieving, etc. there were.

  In recent years, there has been an increasing demand for monodisperse polymer fine particles having a narrow particle size distribution. However, since the conventional method is obtained by sieving or the like, the polymer fine particles have a wide particle size distribution.

Further, since screening and classification are frequent processes, a simple method for producing polymer fine particles that do not require these processes has been desired.
Japanese Patent Laid-Open No. 62-109807

  Then, an object of this invention is to provide the method which can manufacture the polymer fine particle excellent in monodispersibility, without passing through classification processes, such as sieving and classification.

As a result of intensive investigations to solve the problems in the prior art, the present inventor has selectively dispersed fine particles of polymer fine particles by selectively etching the sea phase of the polymer alloy phase-separated into a sea-island structure. Has been found, and the present invention has been completed.
That is, the present invention is a polymer fine particle that contains two or more kinds of polymers and removes the polymer constituting the sea phase from the multicomponent polymer having a sea-island phase separation structure constituted by the two or more kinds of polymers. It relates to the manufacturing method.
In one embodiment of the present invention, the sea-island phase separation structure is formed by spinodal decomposition. In another embodiment of the present invention, the sea-island phase separation structure is formed by reaction-induced phase decomposition.
In the present invention, the average particle size of the polymer fine particles is preferably 0.01 to 30 μm.

  According to the method for producing polymer fine particles of the present invention, polymer fine particles having excellent monodispersibility can be produced without going through a frequent sorting step such as sieving or classification.

The best mode for carrying out the invention will be described below. However, the present invention is not limited to the best mode for carrying out the invention described below.
The present invention provides the production of polymer fine particles that contain two or more kinds of polymers and remove the polymer constituting the sea phase from the multi-component polymer having a sea-island phase separation structure composed of the two or more kinds of polymers. Regarding the method.

The present invention forms a sea-island structure in which two or more polymers are phase-separated, selectively removes the sea phase, and collects the island phase without passing through a sorting step such as sieving or classification. In this method, polymer fine particles having excellent monodispersibility can be obtained.
A multi-component polymer having a sea-island phase separation structure composed of two or more components has a feature that the particle size distribution of the spherical island phase is narrow. The present invention focuses on this feature, and after forming the sea-island phase separation structure, the polymer constituting the island phase is selectively removed by selectively removing the polymer constituting the sea phase. It can be obtained as

  In the present invention, the multi-component polymer has a sea-island phase separation structure, and is a polymer mixture containing at least two polymers of a polymer constituting the sea phase and a polymer constituting the island phase. . The polymer constituting the sea phase and / or the polymer constituting the island phase may each further contain two or more kinds of polymers.

  The polymer contained in the multi-component polymer is not particularly limited, for example, thermoplastic resins such as polyethylene, polypropylene, polycarbonate, polyetheretherketone, polystyrene, polyurethane, polyimide, acrylic rubber, butadiene rubber, acrylonitrile butadiene rubber, etc. And other elastomers.

  Examples of the combination of polymers included in the multi-component polymer, that is, the combination of polymers constituting the sea-island phase separation structure include polycarbonate / polystyrene, polyurethane / acrylic rubber, and the like. In the examples of these combinations, it is preferable that the former is a polymer constituting an island phase and the latter is a polymer constituting an ocean phase.

As a method for forming the sea-island phase separation structure, a method in which two or more kinds of polymers are mixed and uniformly dissolved in a solvent, and then the solvent is removed by heating or reduced pressure can be generally used. If the polymer does not dissolve in the solvent or is difficult to dissolve, for example, by using an extruder and mixing two or more polymers at a temperature equal to or higher than the melting temperature of the polymer and applying shearing, etc. It is possible to use a method of uniformly melting and then cooling. After melting uniformly, injection molding may be performed.
In these methods, a sea-island phase separation structure is usually formed by nucleation or spinodal decomposition.

The blending ratio of the polymer is not particularly limited, but it can be said that when the blending ratio of the polymer to be obtained as fine particles is increased, the amount of the obtained polymer fine particles is increased and the productivity is increased.
However, in consideration of productivity, if the blending ratio of the polymer to be obtained as fine particles is increased too much, the polymer to be obtained as fine particles tends to become a sea phase, and even if the sea phase is removed in the subsequent process. The desired polymer fine particles cannot be obtained.

  That is, generally, a polymer with a low blending ratio tends to be an island phase, and a polymer with a high blending ratio tends to be a sea phase. In view of the above, the amount of polymer to be obtained as fine particles is 10 to 80 parts by weight with respect to 100 parts by weight of the total amount of polymers used to form a multi-component polymer having a sea-island phase separation structure. Is preferred. More preferably, it is 15-60 weight part, More preferably, it is 20-40 weight part. When the blending amount is less than 10 parts by weight, productivity is poor, and when the blending amount exceeds 80 parts by weight, it tends to be difficult to obtain fine particles composed of a desired polymer.

  Examples of the polymer contained in the multi-component polymer include a high-molecular weight (cured) thermosetting resin. The high molecular weight thermosetting resin is usually used in combination with the above-described thermoplastic resin and / or elastomer, and includes a multi-component system including the high molecular weight thermosetting resin and the thermoplastic resin and / or elastomer. The sea-island phase separation structure is constituted by the polymer. In this aspect, it is preferable that the island phase, that is, the obtained polymer fine particles are composed of a thermosetting resin cured product.

  As the thermosetting resin, those which are compatible with the thermoplastic resin or elastomer in the state before high molecular weight (before curing) are preferable. For example, epoxy resin, phenol resin, melamine resin, urea resin, polyurethane, etc. Is mentioned. Epoxy resins are preferred from the viewpoint that they tend to be in an island phase and are not easily etched.

  In this case, as a method of forming the sea-island phase separation structure, a thermosetting resin in a state before curing is further added to the thermoplastic resin and / or elastomer to obtain a mixture, and then the thermosetting in the mixture. A method of curing the resin can be taken. This phenomenon occurs when the thermosetting resin has a high molecular weight, and the high molecular weight thermosetting resin undergoes phase decomposition with the thermoplastic resin and / or elastomer, and is called reaction-induced phase decomposition.

  The combination of the thermosetting resin and the thermoplastic resin and / or elastomer is a mixture of these before the thermosetting resin is cured, but the thermoplastic resin undergoes phase separation as the thermosetting resin is cured. A combination that forms a sea-island phase separation structure composed of a multi-component polymer including a resin and / or elastomer and a high-molecular weight (cured) thermosetting resin is preferable. Examples thereof include epoxy resin / acrylic rubber, epoxy resin / acrylonitrile butadiene rubber, polyurethane / acrylic rubber, and the like. In the illustration of these combinations, it is preferable that the former hardened | cured material is a polymer which comprises an island phase, and the latter is a polymer which comprises a sea phase.

  Specifically, the epoxy resin is preferably an epoxy resin having a glycidyl ether group, such as an aromatic glycidyl ether type epoxy resin or an aliphatic glycidyl ether type epoxy resin, and an aromatic glycidyl ether type epoxy resin. More preferably, it is an epoxy resin. The aromatic glycidyl ether type epoxy resin is not particularly limited as long as it has an aromatic ring and a glycidyl ether group in the molecule. The epoxy resin used in the present invention preferably has two or more glycidyl ether groups in the molecule.

  Specific examples of aromatic glycidyl ether type epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, bisphenol S type epoxy resins, and diglycidyl ethers of naphthalenediol. Of glycidyl ether.

Specific examples of the aliphatic glycidyl ether type epoxy resin include diglycidyl ether of aliphatic diol, triglycidyl ether of aliphatic triol, diglycidyl ether of polyalkylene ether having hydroxyl groups at both ends, glycerin triglycidyl ether, bisphenol A hydrogenated compound of an A type epoxy resin, a hydrogenated compound of a bisphenol F type epoxy resin, and a silicone-modified epoxy resin.
These epoxy resins are used singly or in combination of two or more.

The epoxy resin preferably has a weight average molecular weight of 700 or less, and more preferably 400 or less. When the weight average molecular weight exceeds 700, the thermoplastic resin and / or elastomer tends to phase separate even before curing. Moreover, it is preferable that the weight average molecular weight of an epoxy resin is 110 or more, and it is more preferable that it is 300 or more. If the weight average molecular weight is less than 110, the island phase containing the cured epoxy resin as a component tends to be easily etched.
In the present invention, “weight average molecular weight” refers to a weight average molecular weight in terms of standard polystyrene as measured by gel permeation chromatography (GPC).

  In order to cure the thermosetting resin, the mixture containing the thermoplastic resin and / or elastomer and the thermosetting resin in a state before curing is combined with a curing agent or a curing accelerator alone. May be added. It is preferable to use a curing agent and a curing accelerator that are compatible with a thermoplastic resin, an elastomer, and a thermosetting resin.

  For example, epoxy resin curing agents include phenolic curing agents represented by bifunctional or polyfunctional phenols, acid anhydride curing agents, and aromatic amine curing agents represented by aromatic diamines. Examples of the bifunctional or polyfunctional phenol include bisphenol A and bisphenol F. Examples of the acid anhydride curing agent include phthalic anhydride, tetrahydrophthalic anhydride, pyromellitic anhydride, and the like. Examples of the aromatic diamine curing agent include 4,4′-diaminodiphenylmethane.

  Among these, from the viewpoint that the island phase containing the epoxy resin cured product formed by phase separation is difficult to be etched, a phenol-based curing agent or an aromatic amine-based curing agent is preferable, and bisphenol A, bisphenol F or More preferred is 4,4′-diaminodiphenylmethane. These are used singly or in combination of two or more. Moreover, it is preferable that the weight average molecular weight of a hardening | curing agent is 400 or less from a compatible viewpoint. Furthermore, it is preferable that the weight average molecular weight of a hardening | curing agent is 100 or more from a viewpoint that the island phase which uses an epoxy resin hardened | cured material as a component is hard to be etched.

  The ratio of the epoxy resin to the curing agent is preferably such that the equivalent ratio of the active hydrogen of the curing agent to the epoxy group of the epoxy resin is 0.7 to 1.3. More preferably, it is 0.8-1.2, More preferably, it is 0.9-1.0. When this ratio deviates from the above range, the island phase tends to be easily etched when an island phase containing a cured epoxy resin is formed by phase separation.

  Examples of the curing accelerator include tertiary amines, quaternary ammonium salts, and imidazoles. In particular, as a curing accelerator in a curing reaction between an epoxy resin and a phenolic curing agent, imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-phenylimidazole are preferable. These are used singly or in combination of two or more.

  As for the compounding quantity of a hardening accelerator, 0.05-10 weight part is preferable with respect to a total of 100 weight part of an epoxy resin and a hardening | curing agent as needed. If the blending amount is less than 0.05 parts by weight, the curability may be inferior, and if it exceeds 10 parts by weight, a curing accelerator may remain as an unreacted component. There is a tendency for the island phase to be easily etched.

  There is no particular limitation on the ratio of the total of the thermosetting resin component including the thermosetting resin before curing, the curing agent and, if necessary, the curing accelerator, to the total of the thermoplastic resin and / or elastomer. When it is desired to obtain polymer fine particles made of a thermosetting resin cured product, the total amount of the thermosetting resin component is preferably 15 to 300 parts by weight with respect to 100 parts by weight of the thermoplastic resin and / or elastomer. More preferably, it is 20-200 weight part, More preferably, it is 25-100 weight part. If this blending amount is less than 15 parts by weight, the resulting polymer fine particles are few and the productivity is low, and if it exceeds 300 parts by weight, the cured thermosetting resin is likely to be a sea phase instead of an island phase. There is a possibility that polymer fine particles containing a desired resin as a component cannot be obtained.

  The sea-island phase separation structure is formed in the process of shifting from a single phase region to a two-phase region due to solvent evaporation, temperature change, high molecular weight reaction, and the like. When the above process occurs near the critical point of the phase diagram, the sea-island phase separation structure is often formed by spinodal decomposition. The sea-island phase separation structure formed by spinodal decomposition is an island phase with a particularly high periodicity and a narrow size distribution. That is, in the present invention, polymer fine particles having superior monodispersibility can be produced by forming the island phase by spinodal decomposition.

  In addition, the formation of a sea-island phase separation structure using reaction-induced phase decomposition has a feature that the size distribution of the island phase is extremely narrow and the size of the island phase can be controlled by adjusting the phase decomposition rate and the hardening rate. That is, the island phase tends to be smaller when the curing rate is higher than the phase decomposition rate, and conversely, the island phase tends to be larger when the curing rate is slower than the phase decomposition rate. In the present invention, by utilizing this phenomenon, the distribution of the size of the island phase is narrow, the island phase having a size suitable for the purpose is formed, and then the sea phase is selectively removed, thereby monodispersity. Excellent polymer fine particles can be obtained.

  Although it is possible to obtain polymer fine particles having an arbitrary particle size by the production method of the present invention, the particle size of the polymer fine particles is preferably 0.01 to 30 μm. In particular, the formation of the sea-island structure is performed by reaction-induced phase decomposition, and the particle size of the polymer fine particles can be controlled between 0.01 and 30 μm by adjusting the phase decomposition rate and the curing rate.

  The form of the multicomponent polymer having a sea-island phase separation structure is not particularly limited, and can be, for example, a film form. A film made of a multi-component polymer can be formed by a conventionally known method.

  In the present invention, a process for removing the sea phase is required after the multi-component polymer having the sea-island phase separation structure is formed. The sea phase can be removed, for example, by etching a polymer constituting the sea phase. In the sea phase etching in the present invention, a method capable of selectively etching the sea phase is usually used. That is, it is preferable that the polymer constituting the island phase is difficult to be etched. From the viewpoint that the island phase is difficult to be etched, the island phase is preferably a cured product of a thermosetting resin in which a three-dimensional network is formed, and more preferably an epoxy resin cured product. From the viewpoint that the sea phase is easily etched, a thermoplastic resin or an elastomer is preferable.

As a method for selectively etching the sea phase, generally, solvent etching, acid etching, alkali etching, etc., utilizing the difference in solubility between the polymer constituting the sea phase and the polymer constituting the island phase. used.
Examples of the solvent used for solvent etching include methylene chloride, methyl ethyl ketone, chloroform, tetrahydrofuran, xylene, toluene, heptane, decalin, and the like. These solvents can be used alone or in combination of two or more.

In the acid etching, an acid aqueous solution such as a mixed solution composed of sulfuric acid, phosphoric acid and potassium permanganate, and a mixed solution composed of potassium chromate and sulfuric acid can be used.
In alkaline etching, an aqueous alkali solution such as an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution can be used.

  Moreover, it is also possible to adjust an etching rate by heating or cooling these solvents and solutions. When etching using a solvent or solution, a film composed of a multi-component polymer having a sea-island phase separation structure is immersed in the solvent or solution, or a multi-component polymer on a filter paper that does not allow polymer fine particles to pass through. There is a method of spraying a solvent or a solution after placing a film.

  Another method for selectively etching the sea phase is to use an ion etching apparatus that generates active ions capable of etching a polymer under vacuum conditions.

  The collection of the polymer fine particles formed after the etching is preferably performed using a filter paper or a filter that does not allow the polymer fine particles to pass therethrough, but is not limited thereto. The recovered polymer fine particles are preferably washed with a liquid that does not dissolve the polymer fine particles.

  By the production method of the present invention, monodisperse polymer fine particles having excellent monodispersibility can be obtained. The dispersibility of the resulting polymer fine particles is preferably 1.00 to 1.20, and more preferably 1.00 to 1.10. Dispersibility refers to the ratio of the volume average particle diameter to the number average particle diameter.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1
Acrylic rubber (manufactured by Nagase ChemteX Corporation, weight average molecular weight (Mw) 800,000, molecular weight distribution (Mw / Mn) 2.2) 230 parts by weight as a polymer component, bisphenol A type epoxy resin (manufactured by Toto Kasei Co., Ltd., 60 parts by weight of trade name “YD-8125”, epoxy equivalent 175), 40 parts by weight of bisphenol A (manufactured by Wako Pure Chemical Industries, reagent name “bisphenol A”, molecular weight 228) as a curing agent, and 600 parts by weight of methyl ethyl ketone as a solvent. Blended.

  This was mixed with a stirring motor for 30 minutes to obtain a varnish. This varnish is applied on a polyethylene terephthalate film whose surface has been subjected to a release treatment, heated and dried at 90 ° C. for 5 minutes, and then cured at 170 ° C. for 1 hour to have an epoxy resin cured product with a film thickness of 50 μm in the island phase. A sea-island phase separation structure film was obtained.

  Thereafter, the polyethylene terephthalate film was peeled off, and the sea-island phase-separated structure film was immersed in methyl ethyl ketone at room temperature for 5 hours to etch the acrylic rubber as the sea phase. Thereafter, methyl ethyl ketone containing the island phase as a solid content was filtered using a Kiriyama funnel (filter paper No. 5C). The solid content remaining on the funnel was dispersed in methyl ethyl ketone using an ultrasonic disperser (manufactured by VELBO, VS150), and then the dispersion was filtered with a Kiriyama funnel (filter paper No. 5C). This dispersion-filtration process was repeated three times, and the solid content remaining on the funnel was dried at 60 ° C. under a reduced pressure of 750 mmHg for 20 hours. The dried solid content was crushed using a table mill to obtain polymer fine particles.

(Example 2)
Instead of the above-described curing agent, 1-cyanoethyl-2-phenylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name “CUREZOL 2PZ-CN”) was used as a curing accelerator, and blended in the same manner as in Example 1.

  Specifically, acrylic rubber (manufactured by Nagase ChemteX Corp., weight average molecular weight (Mw) 800,000, molecular weight distribution (Mw / Mn) 2.2) 230 parts by weight as a polymer component, and bisphenol A type epoxy resin (as epoxy resin) Toto Kasei Co., Ltd., trade name “YD-8125”, epoxy equivalent 175) 60 parts by weight and 1-cyanoethyl-2-phenylimidazole (trade name “Curesol 2PZ-CN”, manufactured by Shikoku Kasei Kogyo Co., Ltd.) 1 as a curing accelerator 8 parts by weight were blended. For operations other than blending, polymer fine particles were prepared in the same manner as in Example 1 except that the filter paper used for filtration was replaced with a membrane filter (trade name “A045A” manufactured by ADVANTEC).

(Example 3)
As polymer components, polycarbonate (Mitsubishi Chemical Co., Mn = 32400, Mw / Mn = 1.8) 20 parts by weight, polystyrene (Wako Pure Chemical Industries, Mw = 15000, Mw / Mn = 1.8) 80 parts by weight , And 100 parts by weight of tetrahydrofuran as a solvent. This was mixed with a stirring motor for 30 minutes to obtain a varnish.

  This varnish is coated on a polyethylene terephthalate film whose surface has been release-treated, and dried by heating at 45 ° C. for 1 hour and 120 ° C. for 1 hour, and a sea-island phase-separated structure film having a polycarbonate component with a film thickness of 50 μm in the island phase Got. Thereafter, the polyethylene terephthalate film was peeled off, and the sea-island phase-separated structure film was immersed in toluene at room temperature for 8 hours to etch the polystyrene as the sea phase.

  Thereafter, toluene containing the island phase as a solid content was filtered using a Kiriyama funnel (filter paper No. 5C). The solid content remaining on the funnel was dispersed in toluene using an ultrasonic disperser (manufactured by VELBO, VS150), and then the dispersion was filtered with a Kiriyama funnel (filter paper No. 5C). This dispersion-filtration process was repeated three times, and the solid content remaining on the funnel was dried at 60 ° C. under a reduced pressure of 750 mmHg for 20 hours. The dried solid content was crushed using a table mill to obtain polymer fine particles.

(Comparative Example 1)
In a flask equipped with a Dimroth condenser, a nitrogen inlet, a stirrer, and a thermometer, 500 parts by weight of methanol, 3 parts by weight of sodium dioctylsulfosuccinate, and 10 parts by weight of polyvinylpyrrolidone (Mw = 40000) are blended, and nitrogen gas And stirred for 30 minutes at 70 ° C. to dissolve. A solution in which 120 parts by weight of styrene as a monomer and 1.2 parts by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator were dissolved in advance was placed in the flask and stirred.

  Thereafter, the reaction solution was cooled to 30 ° C. or lower, passed through a 150 mesh wire mesh, a coarse resin lump was removed, and the dispersion liquid passed through the wire mesh was further filtered using a Kiriyama funnel (filter paper No. 5C). Using an ultrasonic disperser (manufactured by VELBO, VS150), the solid content remaining on the funnel was washed in order with methanol and ion-exchanged water, and dried under reduced pressure at 60 ° C. and 750 mmHg for 20 hours to obtain seed particles. It was. Since the seed particles were agglomerated, they were crushed by a table mill (manufactured by Sangen Industry Co., Ltd., WS-2 type).

In a flask equipped with the above-mentioned apparatus, 500 parts by weight of ion exchange water and 1 part by weight of sodium dodecylbenzenesulfonate were blended and dissolved. The seed particles obtained above were dispersed using an ultrasonic disperser, and nitrogen gas was allowed to flow and stirred while maintaining at 15 to 30 ° C.
Next, 720 parts by weight of styrene as a monomer, 0.01 part by weight of divinylbenzene, and 0.7 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator were dissolved in the flask. And stirred for 24 hours. Thereafter, 100 parts by weight of a 5% aqueous polyvinyl alcohol solution (degree of polymerization of 1500 or more) was added to the flask.

  Furthermore, 1.4 parts by weight of p-benzoquinone as a polymerization inhibitor and 0.7 parts by weight of sodium hydrogen carbonate as a pH adjuster were added and maintained at 70 ° C. for 24 hours, heated to 85 ° C. and maintained for 4 hours. After cooling to 30 ° C. or lower, the reaction solution was passed through a 150 mesh wire mesh, and the dispersion that passed through the wire mesh was filtered with a Kiriyama funnel (filter paper No. 5C).

  Using an ultrasonic disperser (manufactured by VELBO, VS150), the solid content remaining on the funnel was dispersed in methanol / ion-exchanged water (50% by weight / 50% by weight), and then the dispersion was used as a Kiriyama funnel (filter paper). No. 5C). This dispersion-filtration process was repeated 5 times, and the solid content remaining on the funnel was dried at 60 ° C. under a reduced pressure of 750 mmHg for 20 hours. The dried solid content was crushed using a table mill to obtain polymer fine particles.

[Evaluation method]
The fine particles obtained in Examples 1 to 3 and Comparative Example 1 were evaluated for volume average particle diameter and dispersibility. The number average particle size and volume average particle size were measured using a laser diffraction scattering method particle size distribution measuring device LS13 320 Multiwave manufactured by Beckman Coulter and a submicron particle analyzer N5 manufactured by the same company. Specifically, first, measurement is performed with a laser diffraction / scattering particle size distribution measuring apparatus LS13 320 multiwave, and when the obtained volume average particle diameter is 1 μm or more, the number average particle obtained by this apparatus is used. The values of diameter and volume average particle diameter were used for evaluation. When the value of the obtained volume average particle diameter was less than 1 μm, the measurement was further performed with a submicron particle analyzer N5, and the number average particle diameter and the volume average particle diameter obtained thereby were used for evaluation. The dispersibility was evaluated by the ratio of the volume average particle diameter to the number average particle diameter using the number average particle diameter and the volume average particle diameter obtained by these measurements.
Table 1 shows the evaluation results of the fine particles obtained in Examples 1 to 3 and Comparative Example 1.

The sea-island phase separation structure obtained in the production process of Example 1 or 2 utilizes reaction-induced phase decomposition. In Example 2, the average particle diameter of the obtained fine particles was smaller than that in Example 1. This is considered to be because Example 2 has a faster curing rate and a slower phase decomposition rate than Example 1. Thus, when the sea-island phase separation structure was formed by reaction-induced phase decomposition to produce fine particles, the particle size of the obtained fine particles could be controlled by adjusting the curing rate and the phase decomposition rate.
In Example 3, spinodal decomposition proceeded by evaporation of the solvent, and a sea-island phase separation structure was formed.

In the production steps of Examples 1 to 3, monodisperse polymer fine particles having excellent monodispersibility could be produced without passing through classification steps such as sieving and classification. Further, the process of obtaining the resin itself was simple and excellent in productivity.
On the other hand, the fine particles obtained in Comparative Example 1 were obtained by radical polymerization and were inferior in monodispersibility. In addition, it has been necessary to go through many manufacturing processes.

Claims (4)

A step of dissolving two or more kinds of polymers in a solvent, removing the solvent , and obtaining a multi-component polymer having a sea-island phase separation structure composed of the two or more kinds of polymers ; and
A method for producing polymer fine particles, comprising a step of removing a polymer constituting a sea phase from a multicomponent polymer having a sea-island phase separation structure .   The method for producing polymer fine particles according to claim 1, wherein the sea-island phase separation structure is formed by spinodal decomposition. The method for producing polymer fine particles according to claim 1 or 2 , wherein the sea-island phase separation structure is formed by reaction-induced phase decomposition.   The method for producing polymer fine particles according to any one of claims 1 to 3, wherein the average particle size of the polymer fine particles is 0.01 to 30 µm.