阅读说明：本技术 中空聚合物颗粒和其制造方法 (Hollow polymer particles and method for producing same ) 是由 原田良祐 于 2019-09-12 设计创作，主要内容包括：一种中空聚合物颗粒,其包含：含有乙烯基系单体单元和磷酸酯系单体单元的聚合物,所述中空聚合物颗粒的体积平均粒径为0.5～1000μm。(A hollow polymeric particle comprising: a polymer comprising a vinyl monomer unit and a phosphate monomer unit, wherein the hollow polymer particles have a volume average particle diameter of 0.5 to 1000 μm.)

1. A hollow polymeric particle comprising: a polymer comprising a vinyl monomer unit and a phosphate monomer unit, wherein the hollow polymer particles have a volume average particle diameter of 0.5 to 1000 μm.

2. The hollow polymeric particle of claim 1, wherein the phosphate-based monomer units have ethylenically unsaturated groups.

3. The hollow polymer particle according to claim 1 or 2, wherein the phosphate-based monomer unit is represented by the following formula (1),

in the formula, R₁Is (meth) acryloyl or allyl, R₂Is a straight-chain or branched alkylene group, m is an integer of 1 to 30, n is 0 or 1, v is an integer of 1 to 10, and x is 1 or 2.

4. A hollow polymeric particle comprising: a polymer containing a vinyl monomer unit,

the content of phosphorus element is 2-200 mg/kg, the content of alkaline earth metal element is 1-100 mg/kg, and the content of phosphorus element is more than that of alkaline earth metal element,

the hollow polymer particles have a volume average particle diameter of 0.5 to 1000 μm.

5. The hollow polymer particle according to any one of claims 1 to 4, having a specific surface area of 1 to 30m²A specific gravity of 0.1 to 0.4g/cm³。

6. The hollow polymer particle according to any one of claims 1 to 4, wherein the inside of the particle has a porous structure.

7. The hollow polymeric particle of any one of claims 1-4, wherein there are only 1 hole inside the particle.

8. A resin composition comprising the hollow polymer particle as claimed in any one of claims 1 to 7.

9. A coating composition comprising the hollow polymeric particles of any one of claims 1 to 7.

10. A cosmetic comprising the hollow polymer particles as defined in any one of claims 1 to 7.

11. A light-diffusing film comprising the hollow polymer particles according to any one of claims 1 to 7.

12. A method for producing hollow polymer particles, characterized in that a monomer mixture containing 0.01-1 part by mass of a phosphate ester monomer unit per 100 parts by mass of a vinyl monomer unit is subjected to suspension polymerization in the presence of a non-polymerizable organic compound and a dispersant.

13. The method for producing hollow polymer particles according to claim 12, wherein the dispersant is a phosphate of an alkaline earth metal.

Technical Field

The present invention relates to hollow polymer particles and a method for producing the same.

Background

Polymer particles having pores inside have been developed as functional members such as a light diffusing agent, a matting agent, a heat insulating agent, and a light weighting agent by utilizing the pores.

Patent document 1 describes an invention relating to hollow porous resin particles composed of a mesoporous structure and an outer contour formed on the surface thereof. The hollow porous resin particles are obtained by allowing an oil-soluble polymerization initiator and a water-soluble polymerization initiator to act simultaneously when a polymerizable monomer is suspension-polymerized in an aqueous system.

However, since the surface layer portion of the hollow porous resin particle is extremely thin and brittle, if an external force is applied, the particle is broken and the inside is exposed at a high risk.

On the other hand, patent document 2 describes porous resin particles made of a methacrylic resin, which are porous inside and have a non-porous surface layer on the surface. The porous resin particles were obtained by swelling micro-crosslinked (0.15%) particles in an alcohol solvent, and then adding dropwise to an aqueous system to precipitate and remove the alcohol.

However, the porous resin particles also have insufficient crosslinked structure and insufficient strength, and therefore, the particles may be deformed by external force and the pores inside the particles may be disintegrated. In addition, the solvent resistance is also insufficient, and it is difficult to use the composition with media other than aqueous media.

As described above, conventional hollow porous particles have insufficient mechanical strength, are likely to be deformed or broken when an external force is applied thereto, and are difficult to maintain their shapes when an external force is applied thereto. When such hollow porous particles having insufficient mechanical strength are used as a light diffusing agent or a matting agent to produce an optical film, a coating material, or the like, the optical film and a coating film formed from the coating material obtained are also easily scratched.

Documents of the prior art

Patent document

Patent document 1: japanese unexamined patent application publication No. 2017-82152

Patent document 2: japanese laid-open patent publication No. 2015-67803

Disclosure of Invention

Problems to be solved by the invention

In view of the above circumstances, an object of the present invention is to provide: hollow polymer particles having high mechanical strength.

Means for solving the problems

The present inventors have made extensive studies to achieve the above object, and as a result, have found that: hollow particles are produced which contain a polymer containing a predetermined monomer unit and have a predetermined volume average particle diameter, and thus hollow particles having high mechanical strength can be provided. The present inventors have further studied based on the above findings, and thus have completed the present invention.

Namely, the present invention provides the following hollow polymer particles.

Item 1.

A hollow polymeric particle comprising: a polymer comprising a vinyl monomer unit and a phosphate monomer unit, wherein the hollow polymer particles have a volume average particle diameter of 0.5 to 1000 μm.

Item 2.

The hollow polymer particles according to item 1, wherein the phosphate-based monomer unit has an ethylenically unsaturated group.

Item 3.

The hollow polymer particle according to item 1 or 2, wherein the phosphate-based monomer unit is represented by formula (1) below.

(in the formula, R₁Is (meth) acryloyl or allyl, R₂Is a straight-chain or branched alkylene group, m is an integer of 1 to 30, n is 0 or 1, v is an integer of 1 to 10, and x is 1 or 2. )

Item 4.

A hollow polymeric particle comprising: a polymer containing a vinyl monomer unit,

the content of phosphorus element is 2-200 mg/kg, the content of alkaline earth metal element is 1-100 mg/kg, and the content of phosphorus element is more than that of alkaline earth metal element,

the hollow polymer particles have a volume average particle diameter of 0.5 to 1000 μm.

Item 5.

The hollow polymer particles according to any one of items 1 to 4, which have a specific surface area of 1 to 30m²A specific gravity of 0.1 to 0.4g/cm³。

Item 6.

The hollow polymer particle according to any one of claims 1 to 4, wherein the inside of the particle has a porous structure.

Item 7.

The hollow polymer particle according to any one of items 1 to 4, wherein the particle has only 1 hole inside.

Item 8.

A resin composition comprising the hollow polymer particle described in any one of items 1 to 7.

Item 9.

A coating composition comprising the hollow polymer particles of any one of items 1 to 7.

Item 10.

A cosmetic comprising the hollow polymer particle described in any one of items 1 to 7.

Item 11.

A light diffusing film comprising the hollow polymer particle as set forth in any one of items 1 to 7.

Item 12.

A method for producing hollow polymer particles, characterized in that a monomer mixture containing 0.01-1 part by mass of a phosphate ester monomer unit per 100 parts by mass of a vinyl monomer unit is subjected to suspension polymerization in the presence of a non-polymerizable organic compound and a dispersant.

Item 13.

The method for producing hollow polymer particles according to item 12, wherein the dispersant is a phosphate of an alkaline earth metal.

ADVANTAGEOUS EFFECTS OF INVENTION

The hollow polymer particles of the present invention have high mechanical strength.

Detailed Description

(first invention: hollow Polymer particles)

The hollow polymer particles of the present invention comprise: a polymer comprising a vinyl monomer unit and a phosphate monomer unit, wherein the hollow polymer particles have a volume average particle diameter of 0.5 to 1000 μm.

The hollow polymer particles of the present invention may have a form having 1 hollow structure inside the particle, and the particle may have a porous structure inside the particle. In addition, the shape of the particles is preferably spherical in view of the mechanical strength of the particles.

The hollow polymer particles have a volume average particle diameter of 0.5 μm or more, preferably 2 μm or more. If the volume average particle diameter of the hollow polymer particles is less than 0.5. mu.m, a large amount of the hollow polymer particles is required to be blended in order to form desired optical characteristics when blended in a coating film or the like, which is uneconomical. On the other hand, the hollow polymer particles have a volume average particle diameter of 1000 μm or less, preferably 100 μm or less, and more preferably 50 μm or less. If the volume average particle diameter of the hollow polymer particles exceeds 1000. mu.m, the hollow polymer particles may fall off from the coating film.

In the present specification, the volume average particle diameter of the hollow polymer particles can be obtained by the Coulter method. Volume average particle diameter of hollow polymer particles Using Coulter Multisizer^TM3(Beckman Coulter Co., Ltd., measuring device manufactured by Ltd.). More specifically, a Multisizer issued in accordance with Beckman Coulter co^TM3 the aperture corrected by the user specification. The pore diameter used for the measurement is appropriately selected depending on the size of the hollow polymer particles to be measured. The Current (aperture Current) and Gain (Gain) are appropriately set depending on the size of the aperture selected. For example, when the aperture having a size of 50 μm is selected, the Current (aperture Current) is set to-800 and the Gain is set to 4. As the measurement samples, the following dispersions were used: a dispersion was prepared by dispersing 0.1g of hollow polymer particles in a 0.1% by weight aqueous nonionic surfactant solution 10m1 using a touch mixer (Yamato Scientific Co., Ltd., "TOUCHMIXER MT-31", manufactured by Ltd.) and an ULTRASONIC cleaner (VELVO-CLEAR, manufactured by ULTRASONIC CLEANER VS-150, manufactured by Kabushiki Kaisha Co., Ltd.). During the measurement, the beaker is not aeratedThe degree of foaming was slowly stirred in advance, and the measurement was terminated at the time of measuring 10 ten thousand hollow polymer particles. The volume average particle diameter of the hollow polymer particles is an arithmetic average in a volume-based particle size distribution of 10 ten thousand particles.

It is preferable that the inside of the hollow polymer particle has a hollow structure or a porous structure, and on the other hand, the surface of the hollow polymer particle is in a non-porous shape. More specifically, the specific surface area of the hollow polymer particles is preferably 1m²More preferably 1.5 m/g or more²More than g. By adopting the above configuration, high light diffusibility can be obtained. On the other hand, the specific surface area of the hollow polymer particles is preferably 30m for the reason that the shrinkage and cracks on the particle surface are small²Less than g, more preferably 25m²The ratio of the carbon atoms to the carbon atoms is less than g. In the present specification, the specific surface area of the hollow polymer particles is defined as a specific surface area defined by ISO 9277, 1 st edition JIS Z8830: 2001 (BET method) (nitrogen adsorption method).

In addition, for the reason of high strength, the hollow polymer particles preferably have a bulk specific gravity of 0.1g/cm³Above, more preferably 0.15g/cm³The above. On the other hand, the hollow polymer particles preferably have a bulk specific gravity of 0.4g/cm for the reason of light weight and light diffusibility by adding a small amount³Less, more preferably 0.35g/cm³The following. In the present specification, the bulk specific gravity of the hollow polymer particles is defined as that measured in accordance with JIS K5101-12-1 (pigment test method-part 12: apparent density or apparent specific volume-part 1: standing method).

The hollow polymer particles are composed of a polymer containing a vinyl monomer unit and a phosphate monomer unit.

The vinyl monomer unit to be used is not particularly limited, and any known vinyl monomer unit can be widely used. Specifically, examples of the monofunctional vinyl monomer unit having 1 ethylenically unsaturated group include (meth) acrylic acid, alkyl ester monomer units of (meth) acrylic acid, 2-hydroxyethyl methacrylate, 2-methoxyethyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, diethylaminoethyl methacrylate, trifluoroethyl methacrylate, heptadecafluorodecyl methacrylate, styrene monomer units, and vinyl acetate. The alkyl group contained in the alkyl ester of (meth) acrylic acid monomer unit may be linear or branched. Examples of the alkyl ester (meth) acrylate monomer include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate; alkyl methacrylates such as n-butyl methacrylate, 2-ethylhexyl methacrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and isobornyl methacrylate. The alkyl group contained in the alkyl ester of (meth) acrylic acid monomer is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. When the number of carbon atoms of the alkyl group contained in the alkyl ester of (meth) acrylate monomer is in the range of 1 to 8, the dispersion liquid during suspension polymerization is excellent in stability, and as a result, hollow polymer particles having high mechanical strength can be easily obtained.

Examples of the styrene monomer include styrene, p-methylstyrene, and α -methylstyrene. Examples of the polyfunctional vinyl monomer unit having 2 or more ethylenically unsaturated groups include a polyfunctional (meth) acrylate monomer unit and an aromatic divinyl monomer unit.

Examples of the polyfunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, tetradecanethylene glycol di (meth) acrylate, decaethylene glycol di (meth) acrylate, heptadecaethylene glycol di (meth) acrylate, 1, 3-butanediol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, phthalic acid diethylene glycol di (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and mixtures thereof, Caprolactone modified hydroxypivalate neopentyl glycol diacrylate, polyester acrylate, urethane acrylate, and the like.

Examples of the aromatic divinyl monomer include divinylbenzene, divinylnaphthalene, and derivatives thereof.

Among the above vinyl monomer units, polyfunctional vinyl monomer units such as ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and divinylbenzene are preferably contained because hollow polymer particles having excellent solvent resistance can be obtained in addition to high mechanical strength.

The content of the polyfunctional vinyl monomer unit is preferably 5% by mass or more, more preferably 10% by mass or more, based on 100% by mass of the total vinyl monomer units. The polyfunctional vinyl monomer unit is contained by 5 mass% or more, and thus a hollow structure is easily formed. On the other hand, the content of the polyfunctional vinyl monomer unit is preferably 50% by mass or less, more preferably 40% by mass or less, of the total 100% by mass of the vinyl monomer units. The content of the polyfunctional vinyl monomer unit is 50% by mass or less, and the resulting hollow polymer particles have a small shrinkage on the surface and a high strength.

The phosphate monomer unit is preferably an acidic phosphate monomer unit because it is easily oriented on the surface of a droplet during suspension polymerization and acts with an inorganic dispersant to increase the hardness in the vicinity of the particle surface.

The acidic phosphate monomer unit is preferably an acidic phosphate monomer having an ethylenically unsaturated group because it is copolymerized with a vinyl monomer in the vicinity of the surface of the droplet during suspension polymerization to increase the particle hardness.

More specific examples of the acidic phosphate ester monomer having an ethylenically unsaturated group include those having the structural formula shown in the following formula (1).

(in the formula, R₁Is (meth) acryloyl or allyl, R₂Is a straight-chain or branched alkylene group, m is an integer of 1 to 30, n is 0 or 1, v is an integer of 1 to 10, and x is 1 or 2. )

More specifically, caprolactone EO-modified phosphodimethacrylate represented by the following formula (2) (product name: KAYAMER PM-21, manufactured by Nippon chemical Co., Ltd.), polyoxypropylene allyl ether phosphate represented by the following formula (3) (product name: ADEKA REASOAP PP-70, manufactured by ADEKA Co., Ltd.), and 2-methacryloyloxyethyl acid phosphate can be exemplified.

(wherein a and b are a-1, b-2, or a-2, b-1.)

(wherein p is an integer of 1 to 30. q is 1 or 2.)

The content of the phosphate monomer unit is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, per 100 parts by mass of the vinyl monomer unit. The monomer unit having a phosphate moiety as a main skeleton is contained in an amount of 0.01 parts by mass or more per 100 parts by mass of the vinyl monomer unit, and thus a hollow structure can be formed. On the other hand, the content of the phosphate monomer unit is preferably 1 part by mass or less, more preferably 0.8 part by mass or less, per 100 parts by mass of the vinyl monomer unit. The phosphate-based monomer unit is 1 part by mass or less based on 100 parts by mass of the vinyl-based monomer unit, and thus the hollow polymer particles obtained can easily maintain a substantially spherical shape. When the phosphate monomer unit and the vinyl monomer unit are copolymerized, a hollow polymer particle having high strength can be obtained, and therefore, this is preferable.

The hollow polymer particles may contain, as needed, 1 or more of various components such as a pigment, an antioxidant, a perfume, an ultraviolet ray protection agent, a surfactant, a preservative, and a pharmaceutically effective component.

(second invention: hollow Polymer particles)

In addition, the present invention includes an invention directed to a hollow polymeric particle comprising: a polymer containing a vinyl monomer unit, wherein the content of phosphorus is 2 to 200mg/kg, the content of alkaline earth metal is 1 to 100mg/kg, the content of phosphorus is greater than the content of alkaline earth metal, and the volume average particle diameter is 0.5 to 1000 μm.

The size and shape of the hollow polymer particles of the second invention are the same as those of the first invention. The vinyl monomer unit is also the same as described above in the first invention.

The content of the phosphorus element in the hollow polymer particles of the second invention is more than the content of the alkaline earth metal. The contents of these elements can be measured by any element analysis, for example, by high-frequency inductively coupled plasma emission spectrometry (ICP emission spectrometry).

The content of phosphorus element in the hollow polymer particles is 2mg/kg or more, preferably 5mg/kg or more. When the content of phosphorus element is less than 2mg/kg, the hollow structure of the hollow polymer particles is not easily formed. On the other hand, the content of phosphorus in the hollow polymer particles is 200mg/kg or less, preferably 100mg/kg or less. If the content of the phosphorus element exceeds 200mg/kg, the mechanical strength of the hollow polymer particles becomes insufficient.

The content of the alkaline earth metal element in the hollow polymer particles is 1mg/kg or more, preferably 3mg/kg or more. In the second invention, the phosphorus element and the alkaline earth metal element form a dense coating film on the surface layer of the hollow polymer particles by the interaction between the phosphorus element and the alkaline earth metal element, and the mechanical strength of the hollow polymer particles is significantly improved. Therefore, when the content of the alkaline earth metal element in the hollow polymer particles is less than 1mg/kg, the above-mentioned coating film is not sufficiently formed, and the mechanical strength of the hollow polymer particles becomes insufficient. On the other hand, the content of the alkaline earth metal element in the hollow polymer particles is 100mg/kg or less, preferably 80mg/kg or less. When the content of the alkaline earth metal element exceeds 100mg/kg, the dispersion stability of the hollow polymer particles in the coating film is deteriorated when the coating film is formed, or the scratch resistance of the film is deteriorated when the film is formed.

The kind of the alkaline earth metal element contained in the hollow polymer particles is not particularly limited. Among them, magnesium or calcium is preferable.

The hollow polymer particles may contain a phosphate monomer unit. For example, the hollow polymer particles are preferably formed of the polymer containing the vinyl monomer unit and the phosphate monomer unit. Examples of the phosphate ester monomer unit include those similar to the first invention.

The specific surface area and bulk density of the hollow polymer particles are the same as those of the first invention.

As in the first invention, the hollow polymer particles may contain, as needed, 1 or more of various components such as a pigment, an antioxidant, a fragrance, an ultraviolet ray protection agent, a surfactant, a preservative, and a medicinal component.

The hollow polymer particles of the first and second inventions have excellent mechanical strength, and can be suitably used for resin compositions, coating compositions, cosmetics, light-diffusing films, and the like. The resin formed from the resin composition obtained using the hollow polymer particles of the present invention, the coating film formed from the coating composition, and the light diffusion film all have remarkable effects of excellent scratch resistance.

(third invention: method for producing hollow Polymer particles)

In addition, the present invention includes inventions relating to a method for producing hollow polymer particles. The method for producing hollow polymer particles of the present invention is characterized by comprising the steps of: a mixture of a non-polymerizable organic compound and a polymerizable monomer, wherein the polymerizable monomer contains 0.01 to 1 part by mass of a polymerizable monomer unit having a phosphate group per 100 parts by mass of a vinyl monomer unit, is subjected to suspension polymerization.

The same monomer units as those described above can be used for the vinyl monomer unit and the monomer unit having a phosphate moiety as a main skeleton.

The mixture of the vinyl monomer unit and the polymerizable monomer unit having a phosphate moiety is subjected to suspension polymerization in the presence of a non-polymerizable organic compound.

The non-polymerizable organic compound has a function as a so-called solvent, and is also advantageous in forming a hollow structure or a porous structure inside the hollow polymer particles.

The non-polymerizable organic compound is preferably an organic solvent having a boiling point of 30 ℃ or higher and 200 ℃ or lower, because it is present in the form of a liquid in the temperature range in which the polymerization step is carried out. More specifically, 1 or more selected from the group consisting of saturated aliphatic hydrocarbons such as n-pentane, isopentane, n-hexane, cyclohexane, and n-heptane, aromatic compounds such as toluene and benzene, acetate-based compounds such as ethyl acetate and butyl acetate, and fluorine-based compounds such as hydrofluoroethers and hydrofluorocarbons can be used.

The amount of the non-polymerizable organic compound used is preferably 10 to 250 parts by mass per 100 parts by mass of the mixture of the vinyl monomer unit and the polymerizable monomer unit having a phosphate moiety. The non-polymerizable organic compound is contained in an amount of 10 parts by mass or more, so that the hollow structure or porous structure inside the hollow polymer particles can be formed more reliably. On the other hand, the non-polymerizable organic compound is 250 parts by mass or less, so that sufficient strength of the resulting hollow polymer particles can be secured.

In order to promote the polymerization of the monomer units used, it is also preferred to use a radical polymerization initiator. The radical polymerization initiator is not particularly limited, and any known one can be widely used.

More specifically, examples of the radical polymerization initiator include oil-soluble azo compounds such as 2,2 '-azobis-2, 4-dimethylvaleronitrile and 2, 2' -azobisisobutyronitrile, and oil-soluble peroxides such as benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, methyl ethyl ketone peroxide, propyl peroxydicarbonate, cumene hydroperoxide and tert-butyl hydroperoxide.

These polymerization initiators may be used alone or in combination of 2 or more. The amount of the polymerization initiator to be added is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, based on 100 parts by mass of the polymerizable monomer, because the polymerization of the polymerizable monomer can be smoothly initiated.

In addition, in the suspension, 1 or more selected from the group consisting of a dispersant, a dispersing aid, a surfactant, a pH adjuster, a water-soluble polymerization inhibitor, and an antioxidant is also preferably added as necessary.

As the dispersant, known dispersants can be widely used, and there is no particular limitation. Among them, an inorganic dispersant is preferably used because a hollow polymer particle having high strength can be obtained. More specifically, salts which are hardly soluble in water such as magnesium pyrophosphate, calcium carbonate, tricalcium phosphate, and barium carbonate, inorganic dispersants such as silica and zirconia, and inorganic polymer substances such as talc, bentonite, silicic acid, diatomaceous earth, and clay can be used. These may be used alone or in combination of two or more.

In the above-mentioned method, when an alkaline earth metal pyrophosphate or phosphate is used as the dispersant, a metal ion interacts with a phosphate ester moiety in a phosphate ester monomer to form a dense coating on a surface layer, and as a result, hollow polymer particles having high strength can be obtained. In addition, as the alkaline earth metal, magnesium or calcium can be suitably used.

The amount of the dispersant to be added is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass, based on 100% by mass of the total amount of the polymerizable monomers, for the purpose of ensuring stability of oil droplets in the polymerizable monomer solution and obtaining hollow polymer particles having a uniform particle diameter.

In order to obtain hollow polymer particles having a further uniform particle diameter, suspension polymerization may be carried out by dispersing droplets using a high-pressure dispersing machine such as a microfluidizer or a Nanomizer which utilizes the collision force between droplets and the collision force against the wall of the machine.

The polymerization temperature is preferably in the range of 30 to 105 ℃. The time for maintaining the polymerization temperature is preferably in the range of 0.1 to 20 hours. After completion of the polymerization, a suspension containing hollow polymer particles containing a non-polymerizable organic compound in the particles is obtained. The suspension was distilled to remove non-polymerizable organic compounds. More preferably, the dispersion stabilizer in the suspension is dissolved and removed with an acid or the like, and then the hollow polymer particles are separated by filtration, the aqueous medium is removed, and the hollow polymer particles are separated by washing with water or a solvent and drying. Alternatively, after completion of the polymerization, the hollow polymer particles may be separated by removing the non-polymerizable organic compound by removing the dispersion stabilizer without distilling the suspension, washing, and drying. The hollow polymer particles of the present invention thus obtained have high mechanical strength, and therefore, can be suitably used as particles for light-weighting agents such as optical films, optical sheets, illumination covers, and the like, matting agents such as paints, inks, and the like, heat-insulating agents for paints, sheets, resins, molded articles, and the like.

While the embodiments of the present invention have been described above, the present invention is not limited to these examples, and it is needless to say that the present invention can be implemented in various forms without departing from the scope of the present invention.

Examples

Hereinafter, embodiments of the present invention will be described more specifically with reference to examples, but the present invention is not limited to these.

[ method of measuring volume average particle diameter of hollow Polymer particles ]

The hollow polymer particles were measured by the Coulter method as follows.

Volume average particle diameter of hollow polymer particles Using Coulter Multisizer^TM3 (measuring apparatus manufactured by Beckman Coulter co., ltd.). The measurement was carried out using a Multisizer published under Beckman Coulter Co., Ltd^TM3 the aperture corrected by the user specification.

The pore diameter used for the measurement is appropriately selected depending on the size of the hollow polymer particles to be measured. The Current (aperture Current) and Gain (Gain) are appropriately set depending on the size of the aperture selected. For example, in the case of selecting an aperture having a size of 50 μm, the Current (aperture Current) is set to-800 and Gain is set to 4. As the measurement samples, the following dispersions were used: a dispersion was formed by dispersing 0.1g of hollow polymer particles in a 0.1% by weight aqueous nonionic surfactant solution 10m1 using a touch mixer (Yamato Scientific Co., Ltd., "TOUCHMIXER MT-31", manufactured by Ltd.) and an ULTRASONIC cleaner (VELVO-CLEAR, manufactured by ULTRASONIC CLEANER VS-150 ", manufactured by Kabushiki Kaisha Co., Ltd.). In the measurement, the inside of the beaker was stirred slowly in advance to such an extent that no air bubbles entered, and the measurement was terminated at the time of measuring 10 ten thousand hollow polymer particles. The volume average particle diameter of the hollow polymer particles is an arithmetic average in a volume-based particle size distribution of 10 ten thousand particles.

(specific surface area)

The specific surface area of the hollow polymer particles is determined by ISO 9277 version 1 JIS Z8830: 2001 (BET method) (nitrogen adsorption method). The BET nitrogen adsorption isotherm of the hollow polymer particles to be treated was measured using an automatic specific surface area/pore distribution measuring apparatus TristarII manufactured by Shimadzu corporation, and the specific surface area was calculated from the nitrogen adsorption amount by the BET multipoint method.

After the pretreatment by purging with a heated gas, nitrogen was used as an adsorbent having a cross-sectional area of 0.162nm²Under the conditions (3), the measurement was carried out by a constant volume method. The pretreatment is specifically performed as follows: the vessel containing the resin pellets was heated at 65 ℃ and purged with nitrogen for 20 minutes, and after natural cooling at room temperature, the vessel was heated at 65 ℃ and degassed under vacuum until the pressure in the vessel became 0.05mmHg or less.

(bulk specific gravity)

The bulk specific gravity of the hollow polymer particles was measured in accordance with JIS K5101-12-1 (pigment test method-part 12: apparent density or apparent specific volume-part 1: static method).

(example 1)

An oil phase was prepared by mixing 105 parts by mass of methyl methacrylate, 45 parts by mass of trimethylolpropane trimethacrylate, 0.3 parts by mass of "KAYAMER (registered trademark) PM-21" (manufactured by Japan chemical co., ltd.), which is a polymerizable monomer having an acidic phosphate group, 0.45 parts by mass of AVN (manufactured by Japan Finechem co. ltd.), 75 parts by mass of ethyl acetate, which is a non-polymerizable organic compound, and 75 parts by mass of cyclohexane. Further, 900 parts by mass of deionized water as an aqueous medium and 23 parts by mass of magnesium pyrophosphate produced by a double decomposition method as a dispersant were mixed to adjust an aqueous phase.

Next, the oil phase was dispersed in the aqueous phase at 8000rpm using a TK-homomixer (manufactured by Primix Corporation) for 5 minutes to obtain a dispersion of approximately 8 μm. Thereafter, the dispersion was placed in a polymerization reactor equipped with a stirrer and a thermometer, the internal temperature of the polymerization reactor was raised to 55 ℃ and stirring of the suspension was continued for 5 hours, and then the internal temperature of the polymerization reactor was raised to 70 ℃ (secondary temperature rise) and the suspension was stirred at 70 ℃ for 2 hours, thereby completing the suspension polymerization reaction.

After the suspension was cooled, the dispersant (magnesium pyrophosphate) contained in the suspension was decomposed with hydrochloric acid. Thereafter, the suspension was dehydrated by filtration to separate the solid content, and the solid content was washed with sufficient water. Thereafter, vacuum drying was performed at 70 ℃ for 24 hours to remove the non-polymerizable organic compound, thereby obtaining spherical polymer particles. The average particle diameter of the resulting polymer particles was 8.0. mu.m. The obtained polymer particles had a porous shape as observed by SEM. The bulk specific gravity was 0.33g/ml, and the specific surface area of the resulting pellets before and after treatment with a jet mill at a pressure of 0.4MPa was measured to find that the specific surface area was 8.2m²/g、23.2m²/g。

(example 2)

Polymer particles were obtained in the same manner as in example 1, except for using 54 parts by mass of styrene, 36 parts by mass of ethylene glycol dimethacrylate, 105 parts by mass of cyclohexane and 105 parts by mass of ethyl acetate.

(example 3)

Polymer particles were obtained in the same manner as in example 1, except that the amount of methyl methacrylate was 135 parts by mass and the amount of trimethylolpropane trimethacrylate was 15 parts by mass.

(example 4)

Polymer particles were obtained in the same manner as in example 1, except that 105 parts by mass of isobutyl methacrylate and 45 parts by mass of ethylene glycol dimethacrylate were used.

(example 5)

Polymer pellets were obtained in the same manner as in example 1 except that 105 parts by mass of styrene, 45 parts by mass of trimethylolpropane trimethacrylate and 0.8 part by mass of "ADEKA REASOAP PP-70" (manufactured by ADEKA Co., Ltd.) as a polymerizable monomer having an acidic phosphate group were used.

(example 6)

Polymer particles were obtained in the same manner as in example 1, except that the non-polymerizable organic compound was changed to cyclohexane in an amount of 150 parts by mass. The resulting particles were those with only 1 pore present in the interior.

(example 7)

In example 1, when the adjusted oil phase was dispersed in the aqueous phase, the rotational speed of the TK-homomixer was changed to 2500rpm, and a dispersion having a particle size of approximately 35 μm was obtained. The subsequent polymerization step and the subsequent polymer particles were obtained in the same manner as in example 1.

(example 8)

An oil phase was prepared by mixing 65 parts by mass of methyl methacrylate, 85 parts by mass of ethylene glycol dimethacrylate, 0.3 part by mass of a polymerizable monomer having an acidic phosphate group "KAYAMER (registered trademark) PM-21", 0.75 part by mass of AVN as a polymerization initiator, 75 parts by mass of ethyl acetate as a non-polymerizable organic compound, and 75 parts by mass of cyclohexane. Further, 900 parts by mass of deionized water as an aqueous medium and 90 parts by mass of tricalcium phosphate as a dispersant were mixed to adjust the aqueous phase.

Except for the above, polymer particles were obtained in the same manner as in example 1. The average particle diameter of the resulting polymer particles was 8.0. mu.m. The obtained polymer particles had a porous shape as observed by SEM. The bulk specific gravity was 0.32g/ml, and the obtained granules were measuredThe specific surface area before and after the treatment with the jet mill at a pressure of 0.4MPa was 7.2m²/g、10.2m²/g。

Comparative example 1

Polymer particles were obtained in the same manner as in example 1, except that KAYMER PM-21 as a polymerizable monomer having an acidic phosphate group was not used. The resulting particles were porous particles.

Comparative example 2

Styrene 105 parts by mass, trimethylolpropane trimethacrylate 45 parts by mass, AVN (manufactured by Japan Finechem co.ltd.) 1.5 parts by mass as an oil-soluble polymerization initiator, and cyclohexane 150 parts by mass as a non-polymerizable organic compound were mixed to adjust an oil phase. Further, 900 parts by mass of deionized water as an aqueous medium, 1 part by mass of sodium lauryl sulfate as a surfactant, and 2.3 parts by mass of VA-057 (manufactured by Wako pure chemical industries, Ltd.) as a water-soluble polymerization initiator were mixed to adjust the aqueous phase.

Subsequently, the oil phase was dispersed in the aqueous phase at 8000rpm by using a TK-homomixer (manufactured by Primix Corporation) for 5 minutes to obtain a dispersion of approximately 8 μm. Thereafter, the dispersion was placed in a polymerization reactor equipped with a stirrer and a thermometer, the internal temperature of the polymerization reactor was raised to 60 ℃ and stirring of the suspension was continued for 5 hours, and then the internal temperature of the polymerization reactor was raised to 70 ℃ (secondary temperature rise) and the suspension was stirred at 70 ℃ for 2 hours, thereby completing the suspension polymerization reaction.

After cooling the suspension, the suspension was dehydrated by filtration to separate the solid content, and the solid content was washed with sufficient water. Thereafter, vacuum drying was performed at 70 ℃ for 24 hours to remove the non-polymerizable organic compound, thereby obtaining polymer particles. The average particle diameter of the resulting polymer particles was 8.0. mu.m. The obtained polymer particles had a porous shape as observed by SEM.

(evaluation test of mechanical Strength)

The hollow polymer pellets of each of the examples and comparative examples were passed through a jet mill (manufactured by Current jet CJ-10 Nisshin Engineering Inc.) under a pressure of 0.4MPa and a feed rate of 5 g/min.

(determination of phosphorus element and alkaline earth Metal element)

The phosphorus element content and the alkaline earth metal element content were measured by a polytype ICP emission spectrometer ("ICPE-9000", manufactured by Shimadzu corporation). About 1.0g of the hollow polymer particles were precisely weighed, and the precisely weighed hollow polymer particles were heated at 450 ℃ for 3 hours using an electric furnace (muffle STR-15K manufactured by Isuzu Motors Limited) to be ashed. The ashed hollow polymer particles were dissolved in 2ml of concentrated hydrochloric acid, and the volume was adjusted to 50ml with distilled water to obtain a measurement sample. Then, the measurement sample was subjected to measurement by the polytype ICP emission spectrometry apparatus under the following measurement conditions, and the peak intensities of the wavelengths of the respective elements (Na, Ca, Mg, Fe, Cr, P) were obtained. Then, from the peak intensities of the obtained wavelengths of the respective elements (Na, Ca, Mg, Fe, Cr, P), the concentrations (μ g/ml) of the respective elements (Na, Ca, Mg, Fe, Cr, P) in the measurement sample were calculated based on a standard curve for quantification prepared by the following standard curve preparation method. Then, the calculated concentration Tc (μ g/ml) of each element (Na, Ca, Mg, Fe, Cr, P) and the weight W (g) of the precisely weighed hollow polymer particles were substituted into the following formula to calculate the amount of each element in the hollow polymer particles.

Element amount ═ (Tc (μ g/ml)/w (g) x 50(ml)

< measurement Condition >

Measuring wavelength: na (589.592nm), Ca (317.933nm), Mg (285.213nm), Fe (238.204nm), Cr (205.552nm), P (177.499nm)

Observation direction: axial direction

High-frequency power: 1.20kW

Carrier flow rate: 0.7L/min

Plasma flow rate: 10.0L/min

Auxiliary flow rate: 0.6L/min

Exposure time: 30 seconds

< method for preparing standard curve >

The calibration curve was measured using a standard solution (manufactured by SPEX, USA, XSTC-13 (general purpose mixed standard solution)Liquid) ", 31 element mixtures (base 5% HNO₃) About 10mg/l each) were prepared by stepwise dilution with distilled water to prepare standards at concentrations of 0ppm (blank), 0.2ppm, 1ppm, 2.5ppm and 5ppm, respectively. The standard solutions of the respective concentrations were measured by the polytype ICP emission spectrometry apparatus under the above measurement conditions, and the peak intensities of the wavelengths of the respective elements (Na, Ca, Mg, Fe, Cr) were obtained. For each element (Na, Ca, Mg, Fe, Cr), the concentration and peak intensity were plotted, an approximation line (straight line or quadratic curve) by the least square method was obtained, and the obtained approximation line was used as a standard curve for quantification.

As shown in table 1 below, the hollow polymer particles of each comparative example were disintegrated by the jet mill treatment, and the internal porous structure was exposed, so that the specific surface area was significantly increased as compared with that before the jet mill treatment. In contrast, it was confirmed that the hollow polymer particles of each example tended to suppress an increase in specific surface area after the jet mill treatment.

[ Table 1]

(example 9)

7.5 parts by mass of the hollow polymer particles obtained in example 2, 30 parts by mass of an acrylic resin (product name ACRYDIC A811, manufactured by DIC Co., Ltd.), 10 parts by mass of a crosslinking agent (product name VM-D, manufactured by DIC Co., Ltd.), and 50 parts by mass of butyl acetate as a solvent were mixed in a stirring and defoaming device for 3 minutes and defoamed for 1 minute to obtain a light-diffusing resin composition.

The obtained light-diffusing resin composition was applied to a 125 μm thick PET film using a coating apparatus equipped with a plate having a gap of 50 μm, and then dried at 70 ℃ for 10 minutes to obtain a light-diffusing film a.

Comparative example 3

A light-diffusing film B was obtained in the same manner as in example 9, except that the hollow polymer particles obtained in comparative example 2 were used.

(evaluation test of scratch resistance)

The coated surface of the obtained light diffusion film was subjected to reciprocal polishing 20 times with a cloth using a crockfastness tester, and the polished light diffusion film was visually observed for scratches. The case where the scratch was not caused and the coating film was peeled off was marked as "o", and the case where the scratch was caused and the coating film was peeled off was marked as "x".

(measurement of haze and Total light transmittance)

The total light transmittance of the light diffusing film was measured in accordance with JIS K7361-1, and the haze (haze) was measured in accordance with JIS K7136. Specifically, the total light transmittance and haze of the light diffusion film were measured using a haze meter (NDH2000) commercially available from japan electrochromism industries.

As shown in table 2 below, the film of comparative example 3 did not have preferable results in the evaluation of scratch resistance. On the other hand, the film of example 9 was evaluated for good scratch resistance.

[ Table 2]

	Haze degree	Total light transmittance	Scratch resistance
				Light diffusing film A	87％	62％	○
Light-diffusing film B	85％	63％	×