JP2007077225A - Hollow resin particle and thermally expanding microcapsule - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow resin particle wherein heat resistance is drastically improved while a low specific density is retained. <P>SOLUTION: The hollow resin particle has a polymer shell (PS) comprising a polymer (P) having a monomer comprising 65-87 mol% acrylonitrile, 8-20 mol% methacrylic acid and 5-15 mol% (meth)acrylate as an essential compositional unit. Preferably, methyl methacrylate, isobonyl methacrylate or 2-hydroxyethyl methacrylate is used as the (meth)acrylate, and more preferably, methyl methacrylate and 2-hydroxyethyl methacrylate are used in combination. With the object of preventing specific density deterioration at an elevated temperature, the polymer shell (PS) preferably contains 1-10 wt.% volatile liquid (SL) based on the weight of the hollow resin particle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to hollow resin particles and thermally expandable microcapsules for producing the hollow resin particles.

Since the hollow resin particles have a very low specific gravity and a small particle size, they have been used in various resin materials, paints, building materials and the like for the purpose of reducing weight and improving heat insulation. However, if the heat resistance of the hollow resin particles is low, the particles are likely to coalesce in the production process such as polymerization of the heat-expandable microcapsules and heat expansion, and the particles are not subjected to the classification process, which is an expensive process. It cannot be used for applications such as electronic materials and synthetic wood that require fineness. Further, even when the hollow resin particles are used, the coalescence of the particles and the deterioration of the specific gravity occur, so that it is difficult to apply to materials used at high temperatures.
Therefore, many studies have been made to improve the heat resistance of the hollow resin particles. For example, from 80% by weight or more of nitrile monomer, 20% by weight or less of non-nitrile monomer and 0.1 to 1% by weight of a crosslinking agent. Hollow resin particles having a polymer as a shell (see, for example, Patent Document 1), nitrile monomers of 80% by weight or more, non-nitrile monomers of 19.95% by weight or less, tetrafunctional or higher functional crosslinking agents and / or long side chains A hollow resin particle (for example, see Patent Document 2) and the like having a polymer made of 0.05 to 1% by weight of a crosslinking agent as a shell has been reported.
JP 62-286534 A JP2002-320843

  Conventional hollow resin particles have a cross-linking agent as an essential constituent unit and are trying to improve heat resistance by the effect of the cross-linking agent. However, if the amount of the crosslinking agent is excessively increased, the specific gravity of the hollow resin particles obtained by reducing the expansion ratio of the thermally expandable microcapsules does not decrease. On the other hand, when the amount of the crosslinking agent is small, the heat resistance is not improved. Therefore, the heat resistance improvement method using the crosslinking agent cannot achieve both heat resistance and low specific gravity. That is, an object of the present invention is to provide hollow resin particles that have both heat resistance and low specific gravity.

  The hollow resin particles of the present invention are characterized by a polymer (P) having an essential constituent unit of a monomer comprising acrylonitrile 65 to 87 mol%, methacrylic acid 8 to 20 mol%, and (meth) acrylate 5 to 15 mol%. The gist is that it has a polymer shell (PS).

  According to the hollow resin particles of the present invention, the heat resistance can be greatly improved while maintaining the low specific gravity, which is a major characteristic of the hollow resin particles.

The contents (mol%) of acrylonitrile, methacrylic acid, and (meth) acrylate, which are essential constituent units of the polymer (P), are based on the total number of moles of all essential constituent units, acrylonitrile 65 to 87, methacrylic acid 8 -20 and (meth) acrylates 5-15. Outside this range, the heat resistance and low specific gravity of the hollow resin particles of the present invention cannot be compatible.
More preferably, they are acrylonitrile 70-85, methacrylic acid 9-17, (meth) acrylate 6-13, Most preferably, they are acrylonitrile 75-83, methacrylic acid 10-14, (meth) acrylate 7-12.

As the (meth) acrylate, an alkyl (meth) acrylate having 4 to 24 carbon atoms can be used, and methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (Meth) acrylate, dodecyl (meth) acrylate, isobornyl (meth) acrylate and the like can be mentioned.
In addition, in this specification, (meth) acryl ... means acryl ... and methacryl ... That is, for example, (meth) acrylonitrile means acrylonitrile and methacrylonitrile.

  As (meth) acrylate, in addition to alkyl (meth) acrylate, (meth) acrylate having various functional groups can be used. For example, hydroxyalkyl (meth) acrylate (C2-C20 of alkyl group: 2-hydroxyethyl (meth) acrylate (HEMA), hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc. The same)), aminoalkyl (meth) acrylate (aminoethyl (meth) acrylate, aminoisopropyl (meth) acrylate, aminobutyl (meth) acrylate, aminohexyl (meth) acrylate, etc.), isocyanatoalkyl (meth) acrylate (isocyanate) Natoethyl (meth) acrylate, isocyanatopropyl (meth) acrylate, isocyanatobutyl (meth) acrylate and isocyanatohexyl (meth) acrylate), glycidyl methacrylate (GMA), polyethylene glycol (weight average molecular weight 100 to 10000) mono (meth) acrylate, polyethylene / polypropylene glycol (weight average molecular weight 200 to 10000, oxyethylene content 10 to 90% by weight) mono (meth) acrylate and polypropylene Examples include glycol (weight average molecular weight 100 to 10,000) mono (meth) acrylate.

  Of these, (meth) acrylates having 4 to 15 carbon atoms are preferable, and more preferably methyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, from the viewpoint of coexistence of heat resistance and low specific gravity improvement of the hollow resin particles. Particularly preferred is a combined use of methyl methacrylate and 2-hydroxyethyl methacrylate.

When methyl methacrylate and 2-hydroxyethyl methacrylate are used in combination, the content (mol%) is based on the total number of moles of all essential constituent units, from 4.99 to 14.99 mol%, 2-hydroxy It is preferable that it is 0.01-3 mol% of ethyl methacrylate, More preferably, it is 6-13 mol% of methyl methacrylate, 0.02-0.5 mol% of 2-hydroxyethyl methacrylate, Especially preferably, it is 7-7 mol of methyl methacrylate. 12 mol%, 2-hydroxyethyl methacrylate 0.03-0.3 mol%.
Within this range, the gas barrier property, flexibility and heat resistance of the polymer shell (PS) made of the polymer (P) can be compatible, and the heat resistance and low specific gravity of the hollow resin particles can be sufficiently exhibited. Can do.

  Arbitrary structural units other than acrylonitrile, methacrylic acid and (meth) acrylate include aromatic vinyl hydrocarbons having 8 to 12 carbon atoms, aliphatic vinyl hydrocarbons having 2 to 18 carbon atoms, and alicyclic compounds having 5 to 15 carbon atoms. It is possible to use vinyl hydrocarbons, (meth) acrylamides having 3 to 22 carbon atoms, vinyl sulfonic acids having 2 to 10 carbon atoms, vinyl ethers having 3 to 10 carbon atoms, vinyl ketones having 4 to 11 carbon atoms, crosslinkable monomers, and the like. it can.

Examples of the aromatic vinyl hydrocarbon having 8 to 12 carbon atoms include styrene, α-methyl styrene, vinyl toluene, 2,4-dimethyl styrene, ethyl styrene, isopropyl styrene, butyl styrene, phenyl styrene, cyclohexyl styrene, benzyl styrene, Examples include tilbenzene, hydroxystyrene, vinyl naphthalene, vinyl pyridine, chlorostyrene, aminostyrene, and dichlorostyrene.
Examples of the aliphatic vinyl hydrocarbon having 2 to 18 carbon atoms (D2) include ethylene, propylene, butene, isobutylene, pentene, heptene, octene, dodecene, octadecene 1-buten-3-ol and 2-buten-1-ol. Is mentioned.
Examples of the alicyclic vinyl hydrocarbon having 5 to 15 carbon atoms include vinylcyclohexane, cyclohexene, pinene, limonene and indene.

  Examples of the (meth) acrylamide having 3 to 22 carbon atoms include (meth) acrylamide, N-alkyl (meth) acrylamide (N-methyl (meth) acrylamide, N-butyl (meth) acrylamide, N-benzyl (meth) acrylamide and the like. ), N, N-dialkyl (meth) acrylamide (N, N-dimethyl (meth) acrylamide and N, N-dipropyl (meth) acrylamide), N-hydroxyalkyl (meth) acrylamide (N-hydroxymethyl (meth)) In addition to acrylamide and N-hydroxyethyl (meth) acrylamide), and aminoalkyl (meth) acrylamide (dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, etc.), N-vinyl lactam (N − Nirupiroridon, etc.) and the like can also be used.

  Examples of the vinyl sulfonic acid having 2 to 10 carbon atoms include vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, α-methylstyrene sulfonic acid, (meth) acryloxypropyl sulfonic acid, (meth) acryloxyethane sulfonic acid, 3 -(Meth) acryloyloxy-2-hydroxypropanesulfonic acid and propylallylsulfosuccinic acid, and alkali metal (sodium and potassium) salts, alkaline earth metal (calcium and magnesium) salts, amine salts, ammonium salts, etc. Is mentioned.

  Examples of the vinyl ether having 3 to 10 carbon atoms include vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl butyl ether, vinyl 2-ethylhexyl ether, vinyl phenyl ether, vinyl 2-methoxyethyl ether, vinyl 2-butoxyethyl ether, 2 -Butoxy-2'-vinyloxydiethyl ether, vinyl 2-ethylmercaptoethyl ether, etc. are mentioned.

  Examples of the vinyl ketone having 4 to 11 carbon atoms include vinyl methyl ketone, vinyl ethyl ketone, vinyl phenyl ketone, and vinyl 2-ethylhexyl ketone.

As the crosslinkable monomer, a monomer having at least two vinyl groups can be used, and a diene having 4 to 10 carbon atoms, bis (meth) acrylamide having 8 to 12 carbon atoms, poly (2 to 10 carbon atoms) poly ( A (meth) acrylate, a C6-C9 polyallylamine, a C6-C17 polyallyl ether, a C9-C14 diallyl ester, etc. can be used.
Examples of the diene include butadiene, pentadiene, hexadiene, cyclopentadiene, ethylidene norbornene, divinylbenzene, divinyltoluene, divinylxylene, and diallylcarbinol.
Examples of bis (meth) acrylamide include N, N′-methylenebis (meth) acrylamide, N, N′-ethylenebis (meth) acrylamide, and N, N′-propylenebis (meth) acrylamide.
Poly (meth) acrylates of polyols include polyol di (meth) acrylate {ethylene glycol di (meth) acrylate, poly (degree of polymerization 2-5) ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate and glycerin. Di (meth) acrylate, etc.} and polyol tri or tetra (meth) acrylate {glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, diglycerin tetra (meth) acrylate, etc.} and the like.
Examples of polyallylamine include diallylamine and triallylamine.
Examples of the polyvinyl ether include divinyl ether, diallyl ether {diallyl ether, diallyloxymethane, diaryloxyethane, pentaerythritol diallyl ether, etc.} and tri- or tetra-allyl ether {tetraallyloxyethane, pentaerythritol triallyl ether. And pentaerythritol tetraallyl ether, etc.}.
Examples of diallyl esters include diallyl phthalate, diallyl malonate, diallyl succinate, and diallyl adipate.

The content (mol%) of arbitrary structural units other than acrylonitrile, methacrylic acid and (meth) acrylate is preferably 20 mol% or less based on the total number of moles of essential structural units, more preferably, 1 to 10 mol%, particularly preferably 1 to 5 mol% or less.
Within this range, the gas barrier property, flexibility and heat resistance of the polymer shell (PS) made of the polymer (P) can be compatible, and the heat resistance and low specific gravity of the hollow resin particles can be sufficiently exhibited. Can do.

  Various additives may be used in the hollow resin particles of the present invention as necessary. For example, antioxidants (such as hindered phenol, phosphorus and lactone), ultraviolet absorbers (such as benzotriazole), antibacterial agents, and the like. An agent (such as phenyl ether) and an antistatic agent (such as a polyamide-based copolymer) can be added.

  The softening temperature (° C.) of the hollow resin particles is preferably 110 to 250, more preferably 120 to 220, and particularly preferably 130 to 200. The softening temperature is measured in accordance with JIS K5601-2-2: 1999 5.1 powder method (measurement sample is heated at 50 ° C. and 0.1 to 3 torr for 90 minutes).

The volume average particle diameter (μm) of the hollow resin particles is preferably 0.1 to 200, more preferably 0.5 to 150, and particularly preferably 1 to 100.
The volume average particle size is measured by a laser diffraction type particle size distribution measuring apparatus having a measurement principle {light scattering method (25 ° C.)} described in JIS Z8825-1: 2001 {for example, LA-920 manufactured by Horiba, Shimadzu Manufactured by SALD-1100, etc.).
The volume average particle size can be adjusted by controlling the particle size of the thermally expandable microcapsules, and can be arbitrarily controlled by the heating expansion temperature and time of the thermally expandable microcapsules.

The specific gravity (g / cm ³ ) of the hollow resin particles is preferably 0.6 to 0.008, more preferably 0.5 to 0.01, and particularly preferably 0.4 to 0.02.
Here, the specific gravity of the hollow resin particles means the specific gravity (apparent density) of the whole particle including the hollow portion.
The specific gravity is described in 2. of JIS Z8807-1976 “Method for Measuring Solid Specific Gravity”. It is measured according to a measurement method using a specific gravity bottle (liquid; distilled water or methanol).

As a method for producing the hollow resin particles of the present invention, a polymer having an essential constituent unit of a monomer composed of 65 to 87 mol% of acrylonitrile, 8 to 20 mol% of methacrylic acid, and 5 to 15 mol% of (meth) acrylic acid ester ( After producing a thermally expandable microcapsule containing a volatile liquid (SL) in a polymer shell (PS) made of P), the thermally expandable microcapsule is expanded by heating to make it hollow. is there.
As the heating method, a known method can be applied, and an air dryer, a smooth air dryer and a Nauter mixer (made by Hosokawa Micron), solid air (made by Hosokawa Micron), a universal mixer (made by Dalton), etc. are used. can do.
The heating temperature (° C.) is preferably {the softening temperature of the polymer (P) (NT) -20 to (NT) +70} ° C. (90 to 350 ° C.), more preferably 100 to 330, particularly preferably 140 to 300. Most preferably, it is 150-270.
The heating time is preferably 1 minute to 60 minutes, more preferably 5 to 30 minutes, and particularly preferably 0.5 to 15 minutes.
Heating may be performed in an atmosphere of air, inert gas (such as nitrogen and argon) or vacuum, and resin (urethane resin, acrylic resin, epoxy resin, silicone resin, polyester resin, polyamide resin, polyimide resin, and polyolefin resin) Etc.), in a solvent (DMF, toluene, silicone oil, etc.), etc.
The hollow resin particles can be adjusted in particle size or sharpened in particle size distribution by classification.

The volatile liquid and (SL) are not particularly limited as long as they do not dissolve the constituent components of the polymer shell (PS), and known ones can be used, including hydrocarbons, halogenated hydrocarbons, alcohols, ethers, and the like. Includes ketones and the like.
Volatility means the property that the vapor pressure (MPa) of the liquid at 180 ° C. is 0.1 to 10 (preferably 0.2 to 7.5, more preferably 0.3 to 5.0). That is, the volatile liquid means a liquid (25 ° C.) having such properties.
Examples of the hydrocarbon include hydrocarbons having 5 to 15 carbon atoms such as n-pentane, isobutane, isopentane, n-hexane, isohexane, heptane, benzene, toluene, xylene, cyclohexane, cyclopentane, and methylcyclohexane. It is done.
Examples of the halogenated hydrocarbon include halides having 1 to 4 carbon atoms such as ethyl chloride, methyl chloride, methyl bromide, chloroform, dichlorobutane, and trichloroethane.
As alcohol, C1-C20 alcohol etc. are used, and methanol, ethanol, butanol, cyclohexanol, t-butanol, etc. are mentioned.
As ether, C2-C15 ether etc. are used, and dimethyl ether, diethyl ether, dibutyl ether, diethylene glycol, dioxane, tetrahydrofuran, etc. are mentioned.
As a ketone, a C3-C13 ketone etc. are used, and acetone, methyl isobutyl ketone, methyl ethyl ketone, benzophenone, dicyclohexyl ketone, etc. are mentioned.

Of these, hydrocarbons and halogenated hydrocarbons are preferable from the viewpoint of expansibility, and more preferable are hydrocarbons, and particularly preferable are n-pentane, isobutane, and isopentane.
The content (% by weight) of the volatile liquid (SL) in the thermally expandable microcapsule is preferably 10 to 50, more preferably 11 to 30, and particularly preferably 12 to 20 based on the weight of the hollow resin particles. It is.

The hollow resin particles of the present invention preferably contain 1 to 10% by weight of volatile liquid (SL) in the polymer shell (PS) based on the weight of the hollow resin particles, and more preferably 1.5 to 8% by weight, particularly preferably 2 to 7% by weight.
If it is this range, lightness will not be impaired by the weight of (SL), and (PS) will shrink by the vapor pressure of (SL) remaining inside when the hollow resin particles are exposed to a high temperature. This can be prevented and low specific gravity can be secured.
The hollow resin particles of the present invention can be obtained by expanding the thermally expandable microcapsules by heating. At this time, most (SL) permeates the polymer shell (PS). Accordingly, the heat expansion of the thermally expandable microcapsules is preferably performed in a short time, and the specific heat expansion time is preferably 1 minute to 60 minutes, more preferably 5 to 30 minutes, and particularly preferably 0. .5 to 15 minutes.

The analysis of the content of the volatile liquid (SL) remaining in the polymer shell (PS) of the hollow resin particles is performed by a gas chromatograph in accordance with JIS0114.
The measurement sample is prepared by swelling or dissolving about 1 g of hollow resin particles in about 150 g of DMF and extracting (SL) inside. A commercially available gas chromatograph can be used, for example, GC14B (manufactured by Shimadzu Corporation) can be used. Other specific measurement conditions are as follows. The column was a capillary column DB17 (manufactured by J & WSCIENTIFIC), and the temperature condition was 40 ° C. for 5 minutes. The detection method was a flame ion detection method, and helium was used as the carrier gas. As the internal standard, a non-overlapping peak of (SL) can be used, and for example, propyl acetate or the like can be used.

The thermally expandable microcapsule of the present invention can be produced by a known method. For example, acrylonitrile, methacrylic acid, (meth) acrylate and optionally other monomers, a volatile liquid (SL), and a polymerization initiator are used. The mixture can be produced by suspension polymerization in an aqueous medium containing a surfactant and / or a dispersion stabilizer (Japanese Patent Publication No. 42-26524).
The polymerization temperature (° C.) is preferably 40 to 120, more preferably 45 to 90, and particularly preferably 50 to 80. The polymerization may be performed under atmospheric pressure, but is preferably performed under pressure (atmospheric pressure +0.1 to 1 MPa) so as not to make the volatile liquid or the like (SL) gaseous.
The suspension polymerization is preferably performed in a sealed state using a pressure vessel. Moreover, after suspending with a disperser etc., it may transfer to a pressure-resistant container and suspension polymerization may be carried out, and you may make it suspend in a pressure-resistant container.
After completion of the polymerization, solid-liquid separation and / or washing may be performed by a known method (such as centrifugation or filtration). On the other hand, the product can be produced in a state dispersed in water or in a solvent or the like without performing solid-liquid separation.
In the case of solid-liquid separation and / or washing, it may be dried and / or pulverized below the softening temperature of the polymer shell (PS). Drying and pulverization can be performed by a known method, and an air flow dryer, a normal air dryer, a Nauter mixer (manufactured by Hosokawa Micron), or the like can be used. Further, drying and pulverization can be simultaneously performed by a pulverization dryer or the like.

Although it does not specifically limit as a polymerization initiator, The oil-soluble initiator soluble in a monomer is preferable and a well-known peroxide initiator, an azo initiator, etc. can be used. Of these, azo initiators are preferred, and 2,2′-azobisisobutyronitrile, 1,1′-azobiscyclohexane 1-carbonitrile, and 2,2′-azobis-4-methoxy-2 are more preferred. , 4-dimethylvaleronitrile and 2,2′-azobis-2,4-dimethylvaleronitrile, particularly preferably 2,2′-azobisisobutyronitrile.
When a polymerization initiator is used, the amount used (% by weight) is preferably 0.01 to 5, more preferably 0.05 to 2, particularly preferably 0, based on the total weight of the vinyl monomer as a constituent unit. .1-1.

Examples of the surfactant include anionic surfactants (sodium lauryl sulfate, (poly) oxyethylene (degree of polymerization 1 to 100) sodium lauryl sulfate and (poly) oxyethylene (degree of polymerization 1 to 100) lauryl sulfate triethanolamine, etc. ), Cationic surfactants (stearyltrimethylammonium chloride, diethylaminoethylamide stearate lactate, dilaurylamine hydrochloride and oleylamine lactate, etc.), nonionic surfactants (diethanolamine adipic acid condensate, lauryldimethylamine oxide, Glyceryl monostearate, sorbitan monolaurate and diethylaminoethylamide lactate stearate) and amphoteric surfactants (coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, lauryl hydroxysulfobe Included in and β- laurylamino sodium propionate, etc.), in addition to these surfactants, it is possible to use a polymer type dispersant (polyvinyl alcohol, starch and carboxymethyl cellulose).
Of these, cationic, nonionic and amphoteric surfactants and their combined use with polymeric dispersants are preferred, and more preferred are nonionic active agents and nonionic active agents with polymeric dispersants. Particularly preferred are nonionic active agents.
When a surfactant is used, the amount used (% by weight) is preferably 0.01 to 10, more preferably 0.05 to 5, based on the total weight of the monomer and the volatile liquid (SL). Most preferably, it is 0.1-2.

As the dispersion stabilizer, silica (such as colloidal silica), calcium carbonate, calcium phosphate, aluminum hydroxide, barium carbonate, magnesium hydroxide, or the like is used, and two or more kinds can be used in combination.
Of these, colloidal silica is preferable from the viewpoint of dispersion stability.
When a dispersion stabilizer is used, the amount used (% by weight) is preferably 0.01 to 30, more preferably 0.1 to 20, based on the total weight of the monomer and the volatile liquid (SL). Especially preferably, it is 0.5-10.

The volume average particle size (μm) of the thermally expanded microcapsule is preferably 0.1 to 100, more preferably 0.5 to 60, and particularly preferably 1 to 30.
In addition, when used for lightening materials, such as resin, 10-100 micrometers is preferable, More preferably, it is 20-60 micrometers. Moreover, when using for the coating materials for motor vehicles etc., 0.5-60 micrometers is preferable, More preferably, it is 1-20 micrometers. The volume average particle size is measured by a laser diffraction type particle size distribution measuring apparatus having a measurement principle {light scattering method (25 ° C.)} described in JIS Z8825-1: 2001 {for example, LA-920 manufactured by Horiba, Shimadzu Manufactured by SALD-1100, etc.).
The volume average particle diameter can be controlled by a known method. The type and amount of the surfactant (decreases as the amount increases), the type and amount of the dispersion stabilizer (decreases as the amount increases), the dispersion condition (conditions It can be arbitrarily controlled by, for example, decreasing when tightened).
The shape of the thermally expandable microcapsule may be a needle shape or a flat shape, but is preferably spherical from the viewpoint of expandability. The thickness of the shell varies depending on the volume average particle diameter and the like, but is usually about 0.5 to 75 μm, and can be adjusted by the amount of (SL) (decreasing as the amount is increased).

EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to this.
<Example 1>
120 parts by weight of deionized water, 21.6 parts by weight of a 20% colloidal silica aqueous solution, 1.0 part by weight of adipic acid-diethanolamine condensate and 42 parts by weight of sodium sulfate were uniformly mixed, and then 34 parts by weight of acrylonitrile ( 640 mmol), 7 parts by weight (81 mmol) of methacrylic acid, 8.5 parts by weight (85 mmol) of methyl methacrylate, 12.2 parts by weight of n-pentane and 0.2 parts by weight of azobisisobutyronitrile. In addition, the suspension was stirred for 2 minutes using a homomixer (ROBOMICS, 4000 rpm, manufactured by Special Machinery Co., Ltd.) to obtain a suspension. This suspension was transferred to a pressure-resistant reaction vessel and polymerized at a gauge pressure of 0.25 MPa and 60 ° C. for 20 hours. Next, the polymerization solution was filtered and dried at 60 ° C. for 5 hours to obtain thermally expandable microcapsules. The thermally expandable microcapsules were heated at 180 ° C. for 2 minutes using an electric furnace (manufactured by the company) to obtain hollow resin particles (1). The volume average particle diameter and specific gravity of the hollow resin particles were analyzed, and the remaining amount of n-pentane in the hollow resin particles is shown in Table 1. Moreover, the following heat resistance evaluation was performed and the result was shown in Table 1.

<Remaining amount of n-pentane>
Measurement was performed according to JIS0114 using a gas chromatograph.
In the measurement sample, about 1 g of hollow resin particles are swollen or dissolved in about 150 g of DMF to extract (SL) inside.
The measurement conditions are as follows.
-Equipment used: GC14B (Shimadzu)
Column: DB17 (manufactured by J & WSCIENTIFIC)
・ Detection method: Flame ion detection method ・ Temperature condition: 40 ° C. × 5 minutes ・ Carrier gas: Helium ・ Internal standard: Propyl acetate

<Volume average particle diameter>
In accordance with JIS Z8825-1: 2001, 0.1 g of a measurement sample is dispersed in 100 ml of methyl alcohol and measured using a laser scattering particle size distribution analyzer LA-920 (25 ° C., manufactured by Horiba, Ltd.). did.

<Specific gravity>
2. JIS Z8807-1976 “Method of measuring solid specific gravity” It measured based on the measuring method (liquid; methanol) by a specific gravity bottle.

<Heat resistance evaluation>
After heating 0.1 g of hollow resin particles at 180 ° C. for 60 minutes in an electric furnace (Denken), the volume average particle diameter and specific gravity were measured.

<Examples 2 to 9>
Except for the structural units and amounts used (parts by weight) shown in Tables 1 and 2, the thermally expandable microcapsules were obtained in the same manner as in Example 1 and then in the same manner as in Example 1. Hollow resin particles (2) to (11) were obtained. In addition, the results evaluated in the same manner as in Example 1 are shown in Tables 1 and 2.

<Comparative Examples 1-3>
A hollow resin particle for comparison was obtained in the same manner as in Example 1 after obtaining thermally expandable microcapsules in the same manner as in Example 1 except that the structural units and amounts used (parts by weight) shown in Table 2 were used. Got. Table 2 shows the results evaluated in the same manner as in Example 1.

( )内はモル％

( )内はモル％

Figures in parentheses are mol%.

Figures in parentheses are mol%.

  In the hollow resin particles of Comparative Examples 1 and 3, the specific gravity deteriorated and the volume average particle diameter increased after the heat treatment. The hollow resin particles of the present invention did not change in specific gravity and volume average particle diameter before and after heat treatment, and were extremely excellent in heat resistance. In addition, the hollow resin particles of Comparative Example 2 have a very high specific gravity although the specific gravity and the volume average particle diameter are not changed before and after the heat treatment and the heat resistance is high. Therefore, according to the hollow resin particles of the present invention, the heat resistance can be greatly improved while maintaining the low specific gravity, which is a major characteristic of the hollow resin particles.

The hollow resin particles of the present invention have a sufficiently low specific gravity even when used in a high temperature region (180 ° C. or higher). Therefore, it is suitable for paints for automobiles, fireproof paints, expansive inks and the like. Moreover, the hollow resin particle of this invention can be utilized in the field | area where weight reduction and high heat resistance are requested | required. For example, it is suitable for various resin materials and rubber material weight reduction materials, heat fixing materials for fixing rolls of printers, and the like.

Claims (5)

Hollow resin particles having a polymer shell (PS) comprising a polymer (P) whose essential constituent unit is a monomer comprising 65 to 87 mol% of acrylonitrile, 8 to 20 mol% of methacrylic acid, and 5 to 15 mol% of (meth) acrylate . The hollow resin particle according to claim 1, wherein the (meth) acrylate is methyl methacrylate. The hollow according to claim 1, wherein the (meth) acrylate comprises 4.99 to 14.99 mol% of methyl methacrylate and 0.01 to 3 mol% of 2-hydroxyethyl methacrylate based on the total number of moles of all essential structural units. Resin particles. The hollow resin particle according to any one of claims 1 to 3, wherein the polymer shell (PS) contains 1 to 10% by weight of a volatile liquid (SL) based on the weight of the hollow resin particle. A thermally expandable microcapsule for producing the hollow resin particle according to any one of claims 1 to 4.