JP2006265451A - Magnetic microsphere having functional group on surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin particle including a desired magnetic particle that is easy to handle, has a large surface area, is hard to precipitate even when used in an aqueous dispersion system and bears a functional group such as a carboxy group on the minute resin surface. <P>SOLUTION: The microsphere comprises at least one thermoplastic resin and at least one magnetic material, has a density of 0.9-1.5 g/cc and an average particle size of 0.5-1,000 μm, and bears a carbonyl halide group or a functional group converted from the carbonyl halide group on the surface of the particle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic microsphere, and more particularly to a magnetic resin particle having many functional groups such as carboxyl groups on the surface of the particle. The magnetic resin particles are used for diagnostic reagents, cell separation carriers, cell culture carriers, nucleic acid separation and purification carriers, protein separation and purification carriers, immobilized enzyme carriers, drug delivery carriers, reaction media in microchannels, magnetic toners, magnetic These particles are useful for inks, magnetic paints, etc.

Conventionally, resin particles including magnetic particles are obtained by dispersing oleophilic magnetic particles in a polymerizable monomer, which is subjected to a suspension polymerization method (for example, see Patent Document 1) or an emulsion polymerization method (for example, a patent). For example). Furthermore, a method for introducing a useful carboxyl group into the particle surface is disclosed (see Patent Document 3).
However, since these methods all use a polymerizable monomer as a starting material, the added magnetic particles inhibit the polymerization reaction. For this reason, the content of the magnetic particles is limited, and the size of the magnetic resin particles to be generated is often as small as 1 μm or less. Therefore, it is required to efficiently produce magnetic resin particles having a large surface area that are easy to handle at 1 μm or more, preferably 5 μm or more, regardless of the content of the magnetic particles. In addition, these particles are in a state in which the monomer is polymerized, and have a lower density than a resin melt-molded with a thermoplastic resin or the like, and the solvent easily infiltrates in a dispersion medium of strong acid or strong alkali. In addition, many of the resin types used are those obtained by polymerizing (meth) acrylic acid ester, styrene, or styrene derivatives, and the specific gravity is greater than 1 even in a state where no magnetic particles are included. Accordingly, the resin particles including the magnetic particles are heavier, and when used in an aqueous dispersion medium, inconveniences such as easy precipitation often occur. In particular, when the particle diameter is 5 μm or more, it tends to settle.

  On the other hand, the present inventors efficiently produce spherical resin particles of 0.1 to 1,000 μm, preferably 5 to 500 μm, by melt-phase separation of two types of incompatible thermoplastic resins. A method (melt phase separation method) has been developed (Patent Document 4), which makes it possible to produce microspheres made of various thermoplastic resins. Also, based on this method, a method for producing composite microspheres in which inorganic materials such as magnetic particles are included in these microspheres has been developed (Patent Document 5), and further development of density-controlled magnetic resin microspheres has been developed. (Patent Document 6). However, the surface of these microspheres reflects the characteristics of the raw material resin as it is and does not have many useful functional groups on the surface. Therefore, the present inventors have made various studies and completed the present invention.

JP 59-221302 A Japanese Examined Patent Publication No. 3-57921 Japanese Patent Laid-Open No. 10-8771 JP 61-9433 A JP 2001-114901 A International Publication No. 04/0667609 Pamphlet

  The problem to be solved by the present invention is that the resin particles including the desired magnetic particles are easy to handle, have a large surface area, are difficult to settle even when used in an aqueous dispersion, and have a functional group such as a carboxyl group on a dense resin surface. It is to provide a magnetic microsphere having a group.

The above problems have been solved by the following <1> and <9>. It is shown below with <2>-<8> and <10>-<12> which are preferable embodiments.
<1> Spherical particles containing at least one thermoplastic resin and at least one magnetic material, having a density of 0.9 to 1.5 g / cc and an average particle size of 0.5 to 1,000 μm. A microsphere characterized by having a functional group converted from a halogenated carbonyl group or a halogenated carbonyl group on the particle surface,
<2> The microsphere according to the above <1>, wherein the functional group on the particle surface is a group having at its terminal one selected from the group consisting of a carboxyl group, an amino group, a hydroxyl group, and an —SH group. ,
<3> The microsphere according to <1> or <2>, wherein the average particle size is 10 to 100 μm,
<4> The microsphere according to any one of <1> to <3>, wherein the density is 1.0 to 1.5 g / cc,
<5> The microsphere according to any one of <1> to <4>, wherein the magnetic material is a soft magnetic material,
<6> The microsphere according to any one of <1> to <5>, wherein the magnetic material is a superparamagnetic material,
<7> The microsphere according to <5>, wherein the soft magnetic material is manganese zinc ferrite and / or nickel zinc ferrite,
<8> The microsphere according to any one of <1> to <8>, wherein the content of the magnetic material is 15 to 50% by weight,
<9> Spherical particles containing at least one thermoplastic resin and at least one magnetic material, having a density of 0.9 to 1.5 g / cc, and an average particle size of 0.5 to 1,000 μm, Any one of the above <1> to <8>, which comprises a step of introducing a carbonyl halide group to the surface of the particles by exposure to actinic radiation under stirring in a gas phase or a liquid phase containing oxalyl dihalide A method for producing the microsphere according to claim 1,
<10> The method for producing a microsphere according to <9>, including a step of bringing a spherical compound into which a halogenated carbonyl group has been introduced into contact with a reactive compound,
<11> The method for producing a microsphere according to <9> or <10>, wherein the active radiation is ultraviolet light,
<12> The method for producing a microsphere according to any one of <9> to <11>, wherein the spherical particles are produced by a melt phase separation method.

  According to the present invention, since it is easy to handle and has a large surface area, it is difficult to settle even when used in an aqueous dispersion, and various functional groups can be introduced onto the particle surface by a simple method. It is possible to provide a microsphere that can be applied as a novel material in various fields such as toner, ink, and paint, and a method for manufacturing the same.

The microsphere of the present invention contains at least one thermoplastic resin and at least one magnetic material, has a density of 0.9 to 1.5 g / cc, and an average particle size of 0.5 μm to 1,000 μm. It is a spherical particle, and has a functional group converted from a halogenated carbonyl group or a halogenated carbonyl group on the surface of the particle.
Below, the microsphere of this invention and its manufacturing method are demonstrated in detail.

<Introduction of carbonyl halide group to resin particle surface>
The functional group present on the surface of the resin particle of the microsphere of the present invention is a carbonyl halide group or a functional group converted from a halogenated carbonyl group. As the carbonyl halide group, a carbonyl chloride group and a carbonyl bromide group are preferable, and a carbonyl chloride group is particularly preferable from the viewpoint of cost and the balance between reactivity and stability.
As a method for introducing a carbonyl halide group into the resin particle surface, various known methods are employed. In particular, the method using a radical reaction that occurs under irradiation with actinic radiation described below is preferable in terms of convenience. For example, a spherical particle to be introduced with a carbonyl halide group is exposed to actinic radiation under stirring in a gas phase or a liquid phase containing oxalyl dihalide to introduce a carbonyl halide group on the surface of the resin spherical particle. A microsphere having a carbonyl halide group introduced on the surface of the resin particle can be obtained by the production method including the steps. It is preferable that the spherical particles are kept under stirring because the functional groups can be uniformly introduced onto the particle surface. Oxalyl dihalide is preferably oxalyl dichloride and oxalyl dibromide, particularly preferably oxalyl dichloride, from the viewpoints of cost, reaction conditions, stability, and handling. Moreover, oxalyl dichloride and oxalyl dibromide are liquid at room temperature and can be treated in a liquid phase by being introduced into a reaction treatment vessel as they are, which is preferable.
As a stirring means, a known method can be used. For example, a method of applying a rotational motion to a container in a horizontal tubular reaction container can be employed.

The actinic radiation is not particularly limited as long as oxalyl dihalide reacts, and examples thereof include electron beams such as γ rays, β rays, and X rays, radiation, ultraviolet rays, and the like. Among these, the use of ultraviolet rays is not limited by the place of use, can be downsized, is preferable from the viewpoint of safety, and more preferably ultraviolet rays generated from a mercury lamp.
The method for measuring the amount of introduced halogenated carboxyl group on the surface of the microsphere can be determined, for example, by adding and stirring the microsphere in a solvent such as water or methanol and titrating the resulting acidic solution. In addition, by determining the surface area of the microspheres by a known method, the amount of halogenated carboxyl groups per unit area of the microsphere surface can be determined together with the titration result.

  Hereinafter, in order to facilitate understanding of the present invention, an example using a chlorocarbonylation reaction of C—H by a photochemical reaction of oxalyl dichloride will be shown as one embodiment. This reaction is a reaction that occurs through a reactive active species (radical species) that occurs photochemically, and is stoichiometrically as shown in Formula (1).

ここで、Ｒは微小球体表面の炭素原子残基を示す。

Here, R represents a carbon atom residue on the surface of the microsphere.

<Introduction of functional group converted from carbonyl chloride group>
Furthermore, the said halogenated carbonyl group can be converted into a desired functional group by contacting and reacting the reactive compound which can introduce | transduce a desired functional group into this.
The functional group is preferably a group having one terminal selected from the group consisting of a carboxyl group, an amino group, a hydroxyl group, an —SH group, a sulfonic acid group, and a glycidyl group at the terminal. More preferably, it is a group having at its terminal one selected from the group consisting of a group, a hydroxyl group, and a —SH group. The above functional group is preferred because the hydrophilicity of the microsphere increases and further functional group conversion is easy. These functional groups are selected according to the use of the resin particles.
Examples of reactive compounds include amines such as ethylenediamine and triethylenediamine, glycols such as ethylene glycol, diethylene glycol, and butanediol, dithiols such as ethanedithiol, propanedithiol, and butanedithiol, diethanolamine, hydroxyethylamine, and the like. Preferred examples thereof include compounds having different functional groups, isethionic acid, glycidol and the like. The present invention is not limited to the above-described compounds, and any compound that reacts with a halogenated carbonyl group can be used.
Moreover, you may convert the functional group converted with the reactive compound into another desired functional group by a well-known method.

The reaction for converting the functional group is preferably carried out in an organic solvent. As the organic solvent, it is preferable to use a solvent inert to the conversion reaction. For example, petroleum hydrocarbon solvents such as benzene, toluene, xylene, hexane and heptane, and halogenated hydrocarbons such as methylene chloride, chloroform and carbon tetrachloride. It can be processed by dissolving a compound having a desired functional group in a solvent such as the above and immersing it in the surface of a polymer material having a modified acid chloride residue. At this time, for dehydrohalogenation, tertiary amines such as triethylamine and pyridine, and alkaline reagents such as sodium hydroxide and sodium alkoxide may be allowed to coexist and then washed with water to remove by-products. .
Further, this reaction can be achieved even in a gas phase in which a reactive compound capable of introducing a desired functional group is introduced as a gas. Such a compound can be used as long as it has a low boiling point and a relatively high vapor pressure, or can be easily converted into a gaseous state by heating, and has an advantage such that it does not require a treatment such as washing. . Among these compounds, compounds such as ethylenediamine can be used as those capable of reacting in the gas phase in the gaseous state.

<Thermoplastic resin>
The thermoplastic resin that can be used in the present invention as the resin material including the magnetic material is not particularly limited as long as it satisfies the gist of the present invention, but a polyolefin resin is preferable. When a polyolefin-based resin is used, the specific gravity is as small as 0.83 to 0.95, which is preferable because the specific gravity of the entire particle can be kept relatively small even after addition of magnetic particles. Polyolefin resins include polypropylene, polyethylene, polymethylpentene, poly (1-butene), polyisobutylene, polypropylene, polyvinyl chloride, polystyrene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl acetate, methyl acrylate / methacrylic acid Acid methyl copolymer, acrylonitrile / styrene copolymer, ethylene / vinyl acetate copolymer (EVA), ethylene / acrylic acid copolymer, ethylene / propylene copolymer, ABS resin (acrylonitrile / butadiene / styrene copolymer), thermoplastic elastomer (for example, styrene / butadiene block) Addition polymers such as polymers) are preferred, and polypropylene is particularly preferred.

<Magnetic material>
As the magnetic particles that can be used in the present invention, any particles that are smaller than the size of the target composite microsphere can be used. One of the purposes of including magnetic particles in spherical micro-resin particles is to drive the micro-spheres of the present invention in a micro area under various chemical environments by an external magnetic field, and to disperse, separate, collect, agitate, mix, control the flow rate, valve To perform unit operations such as operations. For the magnetic particles used for such purposes, it is necessary to use a ferromagnetic material having spontaneous magnetization. Here, the ferromagnetic material is a magnetic material having spontaneous magnetization such as ferromagnetism and ferrimagnetism. Such materials are diverse, such as metals, alloys, intermetallic compounds, oxides, and metal compounds. Further, depending on the form of utilization of the microspheres of the present invention, a magnetic material with little residual magnetization is required. In general, a magnetic material exhibiting soft magnetism (hereinafter also simply referred to as “soft magnetic material”) is suitable for such applications. Further, a superparamagnetic material in which a ferromagnetic material has a nano-order size is further preferable.
The filling amount of the magnetic material is preferably 1 to 50% by weight, more preferably 15 to 50% by weight, and still more preferably 15 to 25% by weight with respect to the total weight of the entire microsphere. The above range is preferable because the magnetic material is sufficiently contained in the thermoplastic resin and the magnetic responsiveness of the fine particles is good.

  Typical examples of the metal material include transition metals Fe, Ni, and Co, but alloys with these metals include Fe-V, Fe-Cr, Fe-Ni, Fe-Co, Ni-Co, and Ni-Cu. Ni-Zn, Ni-V, Ni-Cr, Ni-Mn, Co-Cr, Co-Mn, 50Ni50Co-V, 50Ni50Co-Cr and the like can also be used. Among these, a system containing Fe or Ni having a large saturation magnetic moment is preferable, and an Fe—Ni system is particularly preferable. When a material having a large saturation magnetic moment is used, the above object can be achieved with a small filling amount, and composite particles having a density defined by the present invention can be easily obtained. Other metal materials include rare earth Gd and its alloys.

Examples of the intermetallic compound include ZrFe ₂ , HfFe ₂ , FeBe ₂ , REFe ₂ (RE = Sc, Y, Ce, Sn, Gd, Dy, Ho, Er, Tm), GdCo _{2, and the} like. In addition, RECo ₅ (RE = Y, La, Ce, Sm), Sm ₂ Co ₁₇ , Gd ₂ O ₁₇ , Ni ₃ Mn, FeCa, FeNi, Ni ₃ Fe, CrPt ₃ , MnPt ₃ , FePd, FePd ₃ Fe ₃ Pt, FePt, CoPt, CoPt ₃ , Ni ₃ Pt, and the like.

On the other hand, as the oxide, a magnetic oxide having a crystal structure such as a spinel type, a garnet type, a perovskite type, or a magnetoplumbite type can be used.
Examples of the spinel type include MFe ₂ O ₄ (M = Mn, Fe, Co, Ni, Cu, Mg, Zn, Li _0.5 Fe _0.5 ), FeMn ₂ O ₄ , FeCo ₂ O ₄ , NiCo ₂ O ₄ , γ− And Fe ₂ O ₃ . γ-Fe ₂ O ₃ is iron oxide called maghemite. This is known as a material having a relatively low density (about 3.6 g / cm ³ ) and a large saturation magnetic moment, unlike α-Fe ₂ O ₃ (bengal) known as a pigment. Particularly preferred as a filler. All of these are known as soft magnetic materials, but among them, M = (Mn, Zn), (Ni, Zn), that is, manganese zinc ferrite, nickel zinc ferrite, etc. have little residual magnetization and are magnetic resin particles. The recovery / dispersion operation characteristics by the magnetic field are favorable, which is preferable.

Rare earth iron garnet can be used as the garnet type oxide. When expressed by the general formula R ₃ Fe ₅ O ₁₂ , it is known that R = Y, Sm, Zn, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu exhibit ferrimagnetism. Among these, Y, Sm, Yb, Lu, etc. are preferable in that the saturation magnetization is large. Among these, Y has a low density (5.17 g / cm ³ ) and is particularly preferable.

Magnetoplumbite type oxides include MFe ₁₂ O ₁₉ (M = Ba, Sr, Ca, Pb, Ag _0.5 La _0.5 , Ni _0.5 La _0.5 ), M ₂ BaFe ₁₆ O ₂₇ (M = Mn, Fe, Ni). Fe _0.5 Zn _0.5 , Mn _0.5 Zn _0.5 ), M ₂ Ba ₃ Fe ₂₄ O ₄₁ (M = Co, Ni, Cu, Mg, Co _0.75 Fe _0.25 ), M ₂ Ba ₂ Fe ₁₂ O ₂₂ (M = Mn, Co, Ni, Mg, Zn, Fe _0.25 Zn _0.75 ) and the like.
An example of the perovskite oxide is RFeO ₃ (R = rare earth ion).

On the other hand, borides (Co ₃ B, CoB, Fe ₃ B, MnB, FeB, etc.), Al compounds (Fe ₃ Al, Cu ₂ MnAl, etc.), carbides (Fe ₃ C, Fe ₂ C, Mn) are used as metal compounds. ₃ ZnC, Co ₂ Mn ₂ C, etc.), silicides (Fe ₃ Si, Fe ₅ Si ₃ , Co ₂ MnSi, etc.), nitrides (Mn ₄ N, Fe ₄ N, Fe ₈ N, Fe ₃ NiN, Fe _{3) PtN, Fe 2 N 0.75, Mn} 4 N 0.75 C 0.25, Mn 4 N 0.5 C 0.5, such as _{Fe 4 N 1-x C x} ) of the other, phosphide, arsenide compounds, Sb compounds, Bi compounds, sulfides, Se Compounds, Te compounds, halogen compounds, rare earth elements, and the like can also be used.
Other magnetic materials are described in Naoko Kakunobu's "Physics of Ferromagnetic Materials" Yukabo (S58.4 4th edition).
On the other hand, any superparamagnetic material can be used as long as it can obtain a ferromagnetic material as particles having a size of several nanometers to several tens of nanometers. In particular, nanoparticles such as magnetite are preferred.

<Microsphere>
The microsphere of the present invention contains at least one thermoplastic resin and at least one magnetic material, has a density of 0.9 to 1.5 g / cc, and an average particle size of 0.5 to 1,000 μm. It is a spherical particle, and has a functional group converted from a halogenated carbonyl group or a halogenated carbonyl group on the surface of the particle.
The size of the microspheres of the present invention reflects the size of the spherical particles used (average particle size: 0.5 to 1,000 μm) from the viewpoint of the production method. The microspheres of the present invention are larger than the spherical particles by the amount of functional groups introduced into the particle surface, but the average particle diameter is preferably in the range of 0.5 to 1,000 μm, preferably 10 to 100 μm. A range is more preferred. The particle size of the microspheres of the present invention can be selected according to the application.
The density of the microspheres of the present invention is 0.9 to 1.5 g / cc, preferably 1.0 to 1.5 g / cc. It is preferable that the density is within the above range because it is difficult to settle in the aqueous dispersion medium. The density can be adjusted to the above range depending on the content of the magnetic material and other fillers, the selection of the thermoplastic resin to be used, and the like.

The microsphere of the present invention may contain a filler other than the magnetic material. Examples of fillers other than magnetic materials include titanium oxide (titanium white), zinc oxide, lead oxide, aluminum hydroxide, zirconium oxide, cerium oxide, titanium nitride, zirconium nitride, selenium oxide, silicon carbide, silicon nitride, and carbonized. Examples thereof include boron, boron nitride, and strontium aluminate.
These fillers can be used in combination with two or more kinds of fillers having different functions or the same functions as necessary. These fillers are preferably contained inside the spherical particles, but may be localized on the surface of the base spherical particles, or a part thereof may be exposed on the surface of the spherical particles. Further, the filler may be subjected to a surface treatment in advance to facilitate the inclusion and localization in the spherical particles.

The shape of the fine particles of the present invention and the spherical particles that can be used in the present invention is a true sphere or a substantially spherical shape (hereinafter simply referred to as “substantially spherical”) from the viewpoint of the production method. The “substantially spherical” includes a spherical shape, a shape close to a sphere, and a shape close to a spheroid, and has a shape factor SF1 in the range of 100 to 140, but is preferably a true sphere (in the shape factor SF1). 100-138). The shape factor SF1 is an average value of the shape factors, and is calculated by the following method. An optical microscope image of particles dispersed on a slide glass is taken into a Luzex image analyzer through a video camera, and SF1 is obtained from the absolute maximum length and projection area obtained for 50 or more particles by the following formula to obtain an average value. It is a thing.
SF1 = (ML) ² / A × (π / 4) × 100
In the formula, ML represents the absolute maximum length of the particle, and A represents the projected area of the particle.

<Method for producing microsphere>
The microsphere of the present invention contains at least one thermoplastic resin and at least one magnetic material, has a density of 0.9 to 1.5 g / cc, and an average particle size of 0.5 μm to 1,000 μm. The spherical particles are preferably produced by a production method comprising a step of introducing a carbonyl halide group to the particle surface by exposing the spherical particles to actinic radiation under stirring in a gas phase or a liquid phase containing oxalyl dihalide. .
In addition, in order to convert the carbonyl halide group of the spherical particles obtained in the above step into another functional group, the microsphere of the present invention is produced by a production method further comprising a step of bringing the spherical particles into contact with a reactive compound. More preferably.
In addition, although each of the above steps can use known means and methods, it is preferable to use the means and methods described above.

In addition, as a method for producing spherical particles used in the present invention, a known method can be used. For example, the melt phase separation method described in JP-A-2001-114901 can easily produce spherical particles at low cost. It is preferable because it can be produced by the above method.
The melt phase separation method is a method including the following steps (1) to (4). That is,
(1) A thermoplastic resin composition consisting essentially of a thermoplastic resin and at least one filler is mixed with a dispersion medium that is not compatible with the composition at a temperature equal to or higher than the melting point of the composition. And the step of dispersing in fine particles,
(2) Fine particles of the obtained thermoplastic resin composition are cooled to a temperature below its melting point to disperse substantially spherical spherical particles having an average particle size of about 0.01 μm or more and about 1,000 μm or less. A step of making a mixture dispersed in a medium,
(3) a step of mixing the mixture with a developing solvent that is a poor solvent for the resin composition and a good solvent for the dispersion medium, and making the spherical particles into a suspension; and
(4) a step of separating a desired substantially spherical spherical particle from the suspension;
It is a method including.

  The dispersion medium used in the melt phase separation method forms a continuous phase for dispersing the thermoplastic resin composition in fine particles in the dispersion step of the step (1), and is not compatible with the thermoplastic resin. “Not having compatibility” means having no solubility of 1% by weight or more at the heating temperature. The dispersion medium preferably has no compatibility with the thermoplastic resin, and is preferably a poor solvent. Here, the poor solvent refers to a solvent that reduces the solubility of the thermoplastic resin when added to the thermoplastic resin solution at a predetermined temperature. The dispersion medium used in the melt phase separation method may be a mixture of two or more dispersion media, and is a poor solvent over the range of room temperature to the heating temperature of step (1) with respect to the thermoplastic resin composition. It is desirable. The dispersion medium used in the melt phase separation method is used in a volume of 0.5 to 5 times that of the thermoplastic resin composition.

  Preferred examples of the dispersion medium used in the melt phase separation method include polyalkylene oxides such as polyethylene oxide, polyethylene glycol, polyvinyl alcohol and derivatives thereof (acetalized products), polybutene, wax, natural rubber, synthetic rubber such as polybutadiene. Styrene-butadiene copolymer rubber, petroleum resin and the like, and these can be used alone or in combination. Polyalkylene oxides having different degrees of polymerization are commercially available. By appropriately combining these components, the dispersion medium can be adjusted so as to have a desired viscoelasticity at the dispersion temperature in step (1). it can.

  In the melt phase separation method, the melting point of the thermoplastic resin composition refers to a melting point measured by a differential scanning calorimetry (DSC) method. The melting point of the thermoplastic resin composition substantially composed of the thermoplastic resin and the inorganic filler can be approximated by the melting point of the thermoplastic resin. The melting points of various thermoplastic resins are described in handbooks, manufacturer's technical data, etc. (for example, practical plastic dictionary, material edition, supplementary revision, page 320, Table 1-4 (1993, Industrial Research Committee For example, the melting point of nylon 12 is about 180 ° C. In the melt phase separation method, the melting point of the thermoplastic resin is preferably not less than 30 ° C. and not more than 300 ° C. The fine particle dispersion step in step (1). The temperature is preferably 10 to 200 ° C. higher than the melting point of the thermoplastic resin used, preferably 20 to 150 ° C., and preferably mixed at a temperature higher than 20 ° C. If the heating temperature is too low. The thermoplastic resin composition is difficult to disperse in the fine particles and easily becomes entangled, and if the heating temperature is too high, thermal decomposition or the like occurs, which is not preferable.

  In the melt phase separation method, the method and apparatus for dispersing the resin composition in the dispersion medium in the dispersion medium in step (1) is not particularly limited. For example, it can be dispersed by a roll, a Banbury mixer, a kneader, a single screw extruder, a twin screw extruder, or the like. In the granulation method by the melt phase separation method, it is considered to belong to wet stirring granulation. The particle size is considered to be determined by the balance between In order to obtain a uniform particle size distribution, it is preferable to make the shearing force by stirring and the viscoelasticity of the composition uniform. For this purpose, a closed disperser is used and the temperature inside the disperser is set. It is preferable to make the distribution uniform.

  In the melt phase separation method, after step (2), the mixture of the thermoplastic resin composition and the dispersion medium is cooled to a melting point or lower, and then the developing solvent is a poor solvent for the composition and a good solvent for the dispersion medium. And this mixture may be mixed to form a suspension of spherical particles. In this case, after cooling the mixture, the mixture may be pulverized with a crusher or the like, pelletized with a pelletizer, or formed into a sheet with an extruder, a roll, or the like and then immersed in a developing solvent.

  As a developing solvent used in the melt phase separation method, water, an organic solvent and a mixture thereof can be used. When polyalkylene oxides are used as the dispersion medium, water can be used as a developing solvent. The target spherical particles can be separated from the suspension of spherical particles by centrifugation, filtration, or a combination of these methods. The separated spherical particles are used after drying if necessary.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the form in these Examples.
The evaluation method of the magnetic microsphere having a functional group on the surface in the following examples was based on the following method.

<Average particle size>
An optical micrograph of the resin particle sample was taken, 100 to 150 particles were randomly extracted, the particle diameter was measured using a caliper, and the average particle diameter was determined using the median value of the frequency graph.

<Specific gravity>
Measurement was performed 10 times using a helium-substituted pycnometer, and the average value of the last three measurements was taken as the specific gravity (density) of the sample.

<Determining the presence or absence of carbonyl halide groups on the surface>
When the halogenated carbonyl group on the microsphere surface generated by the radical reaction was reacted with a certain amount of pure water, the hydrogen ion concentration in the generated hydrochloric acid aqueous solution was 4 or less in terms of pH, and the introduction of the functional group was considered.

<Magnetic response>
When a 0.1 g sample is dispersed in 5 cc of water in a 10 cc plastic container and a magnetic field (about 50 kA / m) is applied from the outside of the container using a permanent magnet to collect magnetic resin particles in one place, several seconds When responding within, it was considered good.

  However, specific gravity and magnetic responsiveness were measured when microspheres having a carbonyl halide group on the surface of the microsphere were reacted with a carbonyl halide group and water to form a carboxyl group.

Example 1
Manganese zinc ferrite, which has been oleophilically treated to 850 g of polypropylene having a specific gravity of 0.91, is added so that the total weight of the microspheres is 5, 10, 15, 20, 25, 30, 50% by weight, and further polyethylene. Manganese zinc ferrite-containing polypropylene microspheres were obtained by the melt phase separation method using 1,000 g of glycol as a starting material. Next, 5.0 g of dried microspheres were charged into a quartz glass tubular reaction vessel, 2 mL of oxalyl dichloride was added, and the mixture was set in an ultraviolet irradiation apparatus. Then, ultraviolet rays were irradiated for 20 minutes. During this time, stirring was performed by rotating the reaction vessel at a speed of about 50 Hz. After completion of the reaction, the reaction was purged with nitrogen gas at a temperature of 50 to 100 ° C. for about 10 minutes to remove residual oxalyl dichloride. The average particle diameter, specific gravity, presence / absence of functional groups, and magnetic responsiveness of the obtained samples were evaluated. The results are shown in Table 1.

(Example 2)
As a result of treatment under the same conditions except that oxalyl dichloride was introduced into the reaction vessel in the gas phase at a partial pressure of oxalyl dichloride of 100 mmHg and an argon carrier gas partial pressure of 660 mmHg in place of the liquid phase in Example 1, the introduction rate of functional groups However, in all cases, the pH was 4 or less, and it was found that the gas phase reaction was also effective.

(Example 3)
1.0 g of each microsphere obtained in Example 1 was added to 100 ml of ion-exchanged water and stirred at room temperature for 10 minutes. Thereafter, the fine particles were filtered and dried under reduced pressure in a vacuum dryer. As a result of measuring the surface infrared spectral absorption spectrum of the obtained microsphere by reflection FT-IR, the characteristic absorption of the carbonyl chloride group disappeared and the characteristic absorption identified as the carboxyl group was obtained. The specific gravity and magnetic response were the same as those of Example 1.

Example 4
1.0 g of each microsphere obtained in Example 1 was added to 100 ml of a benzene solution containing 1% ethylenediamine and stirred for 10 minutes at room temperature. Thereafter, the fine particles were filtered, and benzene and ethylenediamine were distilled off under reduced pressure in a vacuum dryer. As a result of measuring the infrared spectral absorption spectrum of the obtained microsphere by reflection FT-IR, the characteristic absorption of the carbonyl chloride group disappears, and the broad characteristic absorption identified as the amino group and the amide bond The characteristic absorption based on the stretching vibration of carbonyl group was obtained. The specific gravity and magnetic response were the same as those of Example 1.

(Example 5)
1.0 g of each microsphere obtained in Example 1 was added to 100 ml of a benzene solution containing 1% ethylene glycol and an equal amount of triethylamine, and stirred for 10 minutes at room temperature. Thereafter, the fine particles were filtered and washed with water, and then dried in a vacuum dryer. As a result of measuring the infrared spectral absorption spectrum of the obtained microspheres by reflection FT-IR, the characteristic absorption of the carbonyl chloride group disappears, and the broad characteristic absorption identified as the hydroxyl group and the ester bond The characteristic absorption based on stretching vibration of carbonyl group was obtained. The specific gravity and magnetic response were the same as those of Example 1.

(Example 6)
1.0 g of each microsphere obtained in Example 1 was added to 100 ml of a benzene solution containing 1% 1,2-ethanedithiol and an equal amount of triethylamine, and stirred for 10 minutes at room temperature. Thereafter, the fine particles were filtered and washed with water, and then dried in a vacuum dryer. As a result of measuring the infrared spectral absorption spectrum of the surface of the obtained microsphere by reflection FT-IR, the characteristic absorption of the carbonyl chloride group disappears and the characteristic absorption identified as -SH group and the thiol ester bond The characteristic absorption based on the stretching vibration of carbonyl group was obtained. The specific gravity and magnetic response were the same as those of Example 1.

Claims (12)

Comprising at least one thermoplastic resin and at least one magnetic material;
The density is 0.9 to 1.5 g / cc,
Spherical particles having an average particle size of 0.5 to 1,000 μm,
A microsphere having a carbonyl halide group or a functional group converted from a carbonyl halide group on the particle surface.   The microsphere according to claim 1, wherein the functional group on the particle surface is a group having one terminal selected from the group consisting of a carboxyl group, an amino group, a hydroxyl group, and an —SH group at the terminal.   The microsphere according to claim 1 or 2, having an average particle diameter of 10 to 100 µm.   The microsphere according to any one of claims 1 to 3, wherein the density is 1.0 to 1.5 g / cc.   The microsphere according to any one of claims 1 to 4, wherein the magnetic material is a soft magnetic material.   The microsphere according to any one of claims 1 to 5, wherein the magnetic material is a superparamagnetic material.   The microsphere according to claim 5, wherein the soft magnetic material is manganese zinc ferrite and / or nickel zinc ferrite.   The microsphere according to any one of claims 1 to 7, wherein the content of the magnetic material is 15 to 50% by weight. Dihalogenated spherical particles containing at least one thermoplastic resin and at least one magnetic material, having a density of 0.9 to 1.5 g / cc and an average particle size of 0.5 μm to 1,000 μm The microsphere according to any one of claims 1 to 8, which comprises a step of introducing a carbonyl halide group to the particle surface by exposure to actinic radiation under stirring in a gas phase or a liquid phase containing oxalyl. Production method.   The method for producing microspheres according to claim 9, comprising a step of bringing spherical particles into which a carbonyl halide group has been introduced into contact with a reactive compound.   The method for producing microspheres according to claim 9 or 10, wherein the active radiation is ultraviolet rays.   The method for producing microspheres according to any one of claims 9 to 11, wherein the spherical particles are produced by a melt phase separation method.