JP2006035092A - Method for producing mixture of hollow resin particle and inorganic fine particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a mixture of hollow resin particles and inorganic fine particles in which the sticking property of inorganic fine particles to the surface of the hollow resin particles is high and homogeneous. <P>SOLUTION: In the method for producing the mixture of hollow resin particle and inorganic fine particle, inorganic fine particles B or a water dispersion of the inorganic fine particles B is mixed into a water dispersion of thermal expansion microcapsules A, or the thermal expansion microcapsules A or water dispersion of the thermal expansion microcapsules A is mixed into the water dispersion of the inorganic fine particles B, thereafter, solid-liquid separation or solid-liquid separation and drying is performed to produce cake C of water content 0 to 100 wt.% or to produce powder D of water content 0 to 5 wt.% through the pulverization of the cake C, and the cake C or the powder D is thermally expanded to produce a mixture of the hollow resin particles and the inorganic fine particles B. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for producing a mixture of hollow resin particles and inorganic fine particles.

The hollow resin particles are added to a resin material or the like as a lightening agent. In addition, inorganic fine particles such as calcium carbonate, titanium oxide, or talc are also added as fillers from the viewpoint of improving resin physical properties and reducing costs.
Conventionally, when both hollow resin particles and inorganic fine particles are added to a resin material or the like, a method of adding them separately or a method of adding a mixture of both has been employed. The latter method is superior from the standpoint of simplifying the operation and preventing scattering of hollow resin particles having a very low specific gravity.
As a method for producing a mixture of the two, a method in which inorganic fine particles are mixed with a wet cake of a thermally expandable microcapsule and heated to expand (Patent Document 1), or a mixture of inorganic fine particles in a dried thermally expandable microcapsule is heated and expanded. (Patent Document 2). Here, from the viewpoint of preventing scattering of the hollow resin particles, it is preferable that the inorganic fine particles adhere to the surface of the hollow resin particles.
JP-A-3-273037 JP2003-113039

In a method in which inorganic fine particles are mixed with a heat-expandable microcapsule wet cake and heated to expand, the heat-expandable microcapsules become agglomerated under the influence of residual moisture, resulting in uneven mixing. For this reason, problems such as specific gravity of the resin material to which this is added and variations in physical properties arise. In addition, in the method of mixing inorganic fine particles into dried thermally expandable microcapsules and heating and expanding, the adhesion between the hollow resin particles and the inorganic fine particles is low, which causes a problem of scattering of the hollow resin particles.
That is, an object of the present invention is to create a uniform mixture of hollow resin particles and inorganic fine particles with high adhesion of inorganic fine particles to the surface of the hollow resin particles.

The method for producing a mixture of hollow resin particles and inorganic fine particles according to the present invention comprises mixing an aqueous dispersion of inorganic fine particles (B) or (A) with an aqueous dispersion of thermally expandable microcapsules, followed by solid-liquid separation. The gist of the present invention is that it is formed into a cake or powder having a water content of 0 to 50% by weight and is heated and expanded.
That is, the present invention
The inorganic fine particle (B) or the aqueous dispersion of (B) is mixed with the aqueous dispersion of the thermally expandable microcapsule (A), or the thermally expandable microcapsule ( After mixing A) or the aqueous dispersion of (A), solid-liquid separation, or solid-liquid separation and drying are performed to obtain a cake (C) having a water content of 0 to 100% by weight, or (C) To obtain a powder (D) having a water content of 0 to 5% by weight, and (C) or (D) is heated and expanded to form a mixture of hollow resin particles and inorganic fine particles (B). A method for producing a mixture of hollow resin particles and inorganic fine particles.

  According to the method for producing a mixture of hollow resin particles and inorganic fine particles of the present invention, it is possible to prepare a mixture of hollow resin particles and inorganic fine particles that has high adhesion of inorganic fine particles to the surface of the hollow resin particles and is uniform. it can. Therefore, the resin material or the like to which the present mixture is added has very little variation in specific gravity and physical properties, and can greatly reduce the scattering of the hollow resin particles.

The thermally expandable microcapsule of the present invention means a microcapsule containing an acrylic polymer (AP) as a shell (PS) and containing a volatile liquid and / or a sublimable solid (SL) in the (PS).
The acrylic polymer (AP) is not limited as long as it is a polymer having a vinyl monomer as a structural unit, but the cyano group-containing vinyl monomer (1) is preferably an essential structural unit. As vinyl monomers, in addition to cyano group-containing vinyl monomer (1), (meth) acrylate (2), carboxyl group-containing vinyl monomer (3), amino group-containing vinyl monomer (4), hydroxyl group-containing vinyl monomer (5) , Epoxy group-containing vinyl monomer (6), isocyanato group-containing vinyl monomer (7), vinyl hydrocarbon (8), and crosslinkable vinyl monomer (9).

As the cyano group-containing vinyl monomer (1), any vinyl polymer having a cyano group can be used without limitation. (Meth) acrylonitrile, α-chloro (meth) acrylonitrile, α-ethoxy (meth) acrylonitrile, fumaronitrile, male oil Examples thereof include nitrile, cyanostyrene and a mixture thereof. Among these, from the viewpoint of gas barrier properties, (meth) acrylonitrile, α-chloro (meth) acrylonitrile and α-ethoxy (meth) acrylonitrile are preferable, (meth) acrylonitrile is more preferable, and acrylonitrile is particularly preferable.
In addition, in this specification, (meth) acryl ... means acryl ... and methacryl ... That is, for example, (meth) acrylonitrile means acrylonitrile and methacrylonitrile.

As the (meth) acrylate (2), (meth) acrylate having 4 to 22 carbon atoms is used, and methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic. Acid-2-ethylhexyl, octadecyl (meth) acrylate, and the like. In addition, maleic acid esters having 6 to 12 carbon atoms (such as dimethyl maleate, diethyl maleate and dihexyl maleate) and polyoxyalkylenes having a weight average molecular weight of 100 to 2000 (oxyethylene and / or oxypropylene: random and / or Block) Mono (meth) acrylate (terminal hydroxyl group is etherified or esterified with alkyl group having 1 to 4 carbon atoms (such as methyl, ethyl and butyl) or saturated fatty acid having 2 to 3 carbon atoms (such as acetic acid and propionic acid) Can be used.
Of these, from the viewpoint of heat resistance, (meth) acrylates having 4 to 10 carbon atoms are preferable, methyl (meth) acrylate, ethyl (meth) acrylate and propyl (meth) acrylate are particularly preferable. Is methyl (meth) acrylate.

As the carboxyl group-containing vinyl monomer (3), vinyl carboxylic acid having 3 to 20 carbon atoms or the like is used, and (meth) acrylic acid, (anhydrous) maleic acid, maleic acid monoalkyl ester (alkyl having 1 to 20 carbon atoms). : Maleic acid monoethyl ester, maleic acid monobutyl ester, maleic acid monohexyl ester, etc. (the same applies to alkyl), fumaric acid, fumaric acid monoalkyl ester, crotonic acid, itaconic acid, itaconic acid monoalkyl ester, itacone Acid glycol monoethers (glycols having 2 to 20 carbon atoms: ethylene glycol, propylene glycol, hexene glycol, etc.), citraconic acid, citraconic acid monoalkyl ester, cinnamic acid, etc., and alkali metal (sodium and potassium) salts thereof, A Cali earth metals (calcium and magnesium) salts, amines (C3-20: trimethylamine, triethylamine, butyl dimethylamine and triethanolamine) salts and ammonium salts.
Among these, from the viewpoint of heat resistance and the like, vinyl carboxylic acids having 3 to 10 carbon atoms are preferable, more preferably (meth) acrylic acid, (anhydrous) maleic acid and maleic acid monoalkyl ester, particularly preferably (meth). Acrylic acid.

In addition, the carboxyl group of the carboxyl group-containing vinyl monomer (3) may be blocked with a blocking agent.
The blocking agent of the carboxyl group, the oxime of 2 to 30 carbon atoms {methyl ethyl ketone oxime _{(CH 3 CH 2 CH (CH} 3) = NOH), acetophenone oxime _{(C 6 H 5 CH (CH} 3) = NOH) and benzophenone Oximes ((C ₆ H ₅ ) ₂ CH═NOH) and the like (hereinafter the same) and vinyl compounds having 3 to 30 carbon atoms {2-methylpropene (isobutene) and 2-methylhexene (isoheptane) etc.} etc. It is preferably used, more preferably a vinyl compound, particularly preferably 2-methylpropene (isobutene).
The blocking method is not particularly limited, and can be performed by a known method. The addition amount of the blocking agent is preferably 1 to 2 molar equivalents, more preferably 1.2 to 1.8 molar equivalents, relative to 1 molar equivalent of the functional group to be blocked. The blocking reaction temperature is usually 10 to 150 ° C., but it is preferably performed at a low temperature so that the vinyl monomer is not polymerized, and preferably 10 to 30 ° C. Further, a known catalyst may be added to promote the reaction (the blocking method is the same hereinafter).

As the amino group-containing vinyl monomer (4), an amino group-containing vinyl monomer having 4 to 50 carbon atoms can be used, and aminoalkyl (meth) acrylate (alkyl having 3 to 20 carbon atoms: aminoethyl (meth) acrylate, amino Isopropyl (meth) acrylate, aminobutyl (meth) acrylate, aminohexyl (meth) acrylate and the like (the same applies to alkyl below)), aminoalkylacrylamide (alkyl having 3 to 20 carbon atoms), dimethylacrylamide, (meth) allylamine, Examples include crotylamine, aminostyrene, N-allylphenylenediamine, and 16- (meth) acryloylhexadecylamine.
Among these, from the viewpoint of heat resistance, an amino group-containing vinyl monomer having 4 to 20 carbon atoms is preferable, more preferably an aminoalkyl (meth) acrylate and aminoalkyl (meth) acrylamide having 4 to 20 carbon atoms, particularly preferably. These are aminoalkyl (meth) acrylates having 4 to 10 carbon atoms and aminoalkyl (meth) acrylamides.

The amino group of the amino group-containing vinyl monomer (4) may be blocked with a blocking agent.
Examples of the amino group blocking agent include ketones having 3 to 30 carbon atoms (acetone, methyl isobutyl ketone, methyl ethyl ketone, benzophenone, dicyclohexyl ketone, methyl acetoacetate, ethyl acetoacetate, and acetylacetone) (hereinafter the same) and those having 1 to 1 carbon atoms. 30 carboxylic acids (formic acid, acetic acid, butanoic acid, lauric acid, benzoic acid, toluic acid and the like (hereinafter the same)) and the like are preferably used, and more preferably a ketone is used.

As the hydroxyl group-containing vinyl monomer (5), a hydroxyl group-containing vinyl monomer having 2 to 20 carbon atoms is used, and hydroxyalkyl (meth) acrylate (alkyl 3 to 20 carbon atoms: hydroxyethyl (meth) acrylate, hydroxypropyl ( (Meth) acrylate and hydroxybutyl (meth) acrylate etc. (the same applies to alkyl below)), hydroxyacrylamide (alkyl having 3 to 20 carbon atoms), hydroxystyrene, N-methylol (meth) acrylamide, (meth) allyl alcohol, black Examples include til alcohol, isocrotyl alcohol, 1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol, propargyl alcohol, 2-hydroxyethylpropenyl ether, and sucrose allyl ether. Et In addition, polyethylene glycol (weight average molecular weight 100 to 10,000) (meth) acrylate, polyethylene / polypropylene glycol (weight average molecular weight 200 to 10,000, oxyethylene content 10 to 90% by weight) mono (meth) acrylate and polypropylene glycol (Weight average molecular weight 100 to 10,000) Mono (meth) acrylate and the like can also be used.
Of these, from the viewpoint of heat resistance, hydroxyalkyl (meth) acrylate and hydroxyalkyl (meth) acrylamide are preferable, hydroxyalkyl (meth) acrylate is more preferable, and hydroxyethyl methacrylate (HEMA) is particularly preferable.

In addition, the hydroxyl group of the hydroxyl group-containing vinyl monomer (5) may be blocked with a blocking agent.
As the hydroxyl blocking agent, the above-mentioned ketones and carboxylic acids are preferably used, and more preferably ketones are used.

As the epoxy group-containing vinyl monomer (6), an epoxy group-containing vinyl monomer having 5 to 20 carbon atoms is used, and examples thereof include vinyl glycidyl ether, propenyl glycidyl ether, and glycidyl (meth) acrylate.
Among these, glycidyl methacrylate (GMA) is preferable from the viewpoint of heat resistance.

As the isocyanato group-containing vinyl monomer (7), isocyanatoalkyl (meth) acrylate having 4 to 20 carbon atoms is used, and isocyanatoethyl (meth) acrylate, isocyanatopropyl (meth) acrylate, isocyanatobutyl (meth) ) Acrylate and isocyanatohexyl (meth) acrylate.
Among these, from the viewpoint of heat resistance, isocyanatoalkyl (meth) acrylate having 4 to 10 carbon atoms is preferable, and isocyanatohexyl (meth) acrylate is particularly preferable.

The isocyanato group of the isocyanato group-containing vinyl monomer (7) may be blocked with a blocking agent.
As the blocking agent for the isocyanato group, the above oxime, phenol having 6 to 30 carbon atoms (phenol, cresol, ethylphenol, butylphenol, nonylphenol, dinonylphenol, etc.) and alcohol having 1 to 20 carbon atoms (methanol, ethanol, butanol) , Cyclohexanol, t-butanol, triethyl carbinol, tributyl carbinol and triphenyl carbinol) are preferably used, more preferably oxime and alcohol, particularly preferably methyl ethyl ketone oxime, methanol and butanol.

Examples of the vinyl hydrocarbon (8) include an aromatic vinyl hydrocarbon having 8 to 12 carbon atoms, an aliphatic vinyl hydrocarbon having 2 to 18 carbon atoms, and an alicyclic vinyl hydrocarbon having 5 to 15 carbon atoms.
Aromatic vinyl hydrocarbons include styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotylbenzene, hydroxystyrene, Examples include vinyl naphthalene, vinyl pyridine, chlorostyrene and dichlorostyrene.
Examples of the aliphatic vinyl hydrocarbon include ethylene, propylene, butene, isobutylene, pentene, heptene, octene, dodecene, octadecene, and the like.
Examples of the alicyclic vinyl hydrocarbon include vinylcyclohexane, cyclohexene, pinene, limonene and indene.

  As the crosslinkable vinyl monomer (9), a vinyl monomer having at least two vinyl groups and a vinyl monomer that generates a vinyl group at a high temperature (100 to 200 ° C.) can be used.

Examples of the vinyl monomer having at least two vinyl groups include diene having 4 to 10 carbon atoms, bis (meth) acrylamide having 8 to 12 carbon atoms, poly (meth) acrylate having a polyol (2 to 10 carbon atoms), and 6 carbon atoms. -9 polyallylamine, C6-C17 polyallyl ether, C9-14 diallyl ester, etc. are contained.
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.
Among these, from the viewpoint of heat resistance, a vinyl monomer having two vinyl groups is preferable, more preferably diene, bis (meth) acrylamide, divinyl ether and di (meth) allyl ether, particularly preferably diene and di ( (Meth) allyl ether.

As the acrylic polymer (AP), from the viewpoint of expansibility and heat resistance, at least one vinyl monomer selected from the group consisting of a cyano group-containing vinyl monomer (1) and vinyl monomers (2) to (8), etc. Are preferably structural units.
In addition, when the vinyl monomer which has a functional group which is easy to react mutually is used as a structural unit, it is preferable to block the functional group of one vinyl monomer with a blocking agent from a viewpoint of expansibility. For example, when the carboxyl group-containing vinyl monomer (3) and the epoxy group-containing vinyl monomer (6) are used as structural units, the carboxyl group in (3) is preferably blocked with a blocking agent. When the isocyanate group-containing vinyl monomer (7) and the amino group-containing vinyl monomer (4) and / or the hydroxyl group-containing vinyl monomer (5) are used as constituent units, the isocyanate group in (7) is blocked by a blocking agent. It is preferable that
Of the other vinyl monomers, (meth) acrylate (2), carboxyl group-containing vinyl monomer (3) and amino group-containing vinyl monomer (4) are preferred.

When the cyano group-containing vinyl monomer (1) and at least one vinyl monomer selected from the group consisting of vinyl monomers (2) to (8) are used as constituent units, the inclusion of the cyano group-containing vinyl monomer (1) unit The amount (mol%) is preferably from 50 to 99.5, more preferably from 60 to 96, particularly preferably from 70 to 93, based on the total number of moles of the vinyl monomer as a constituent unit. Within this range, the gas barrier properties can be sufficiently exerted and the expansibility can be further improved.
The content (mol%) of at least one vinyl monomer unit selected from the group consisting of vinyl monomers (2) to (8) is 0.5 to 50 based on the total number of moles of vinyl monomers as constituent units. Is more preferable, 4 to 40 is more preferable, and 7 to 30 is particularly preferable. Within this range, the expansibility and heat resistance are further improved.

When the (meth) acrylate (2) or the carboxyl group-containing vinyl monomer (3) is included as a structural unit, the content (mol%) is 0.5 to 0.5 based on the total number of moles of the vinyl monomer as the structural unit. 50 is preferable, more preferably 2 to 30, and particularly preferably 5 to 20. Within this range, the expansibility and heat resistance are further improved.
When the amino group-containing vinyl monomer (4) is included as a structural unit, the content (mol%) is preferably 0.01 to 20, more preferably 0 based on the total number of moles of the vinyl monomer as the structural unit. 0.05 to 15 and particularly preferably 0.1 to 10. Within this range, the expansibility and heat resistance are further improved.
When the hydroxyl group-containing vinyl monomer (5), epoxy group-containing vinyl monomer (6), isocyanato group-containing vinyl monomer (7) or vinyl hydrocarbon (8) is included as a constituent unit, this content (mol%) Based on the total number of moles of vinyl monomer as a unit, 0.01 to 20 is preferable, 0.05 to 15 is more preferable, and 0.09 to 10 is particularly preferable. Within this range, the expansibility and heat resistance are further improved.
When the crosslinkable vinyl monomer (7) is included as a structural unit, the content (mol%) is preferably 0.01 to 10 based on the total number of moles of the vinyl monomer as the structural unit, more preferably 0.8. 05 to 5, particularly preferably 0.09 to 1. Within this range, the expansibility and heat resistance are further improved.

  The weight average molecular weight (Mw) of the acrylic polymer (AP) is preferably 5,000 to 1,000,000, more preferably 10,000 to 500,000, and particularly preferably 20,000 to 300,000. Mw is measured by gel permeation chromatography using polystyrene as a standard substance.

The acrylic polymer (AP) may contain a compound having a reactive group that reacts with the functional groups of the vinyl monomers (2) to (7), an organic filler, a colorant, and the like.
Examples of the compound having a reactive group that reacts with the functional group of the vinyl monomers (2) to (7) include polyisocyanate {2,4- or 2,6-tolylene diisocyanate (TDI), 2,4′- or 4 , 4'-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)}, polycarboxylic acids {isophthalic acid, malonic acid terephthalic acid, succinic acid, adipic acid, hexanetricarboxylic acid and 1,3 -Cyclopentanedicarboxylic acid etc.}, polyamine {ethylenediamine, bis (hexamethylene) triamine, isophoronediamine and 1,3- or 1,4-phenylenediamine etc.}, polyol {ethylene glycol, propylene glycol, glycerin and bisphenol A etc} Epoxide {ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, diglycidyl adipate, limonene dioxide, pentaerythritol triglycidyl ether and bisphenol A diglycidyl ether and the like}, and mixtures of two or more of them may be used. When these compounds are contained, if the functional groups of the vinyl monomers (2) to (7) are not blocked, the reactive groups in these compounds are blocked from the viewpoint of expansibility. It is preferable to block with an agent (blocking agent and blocking method are the same as in the case of vinyl monomer).
When a compound having a reactive group that reacts with the functional groups of the vinyl monomers (2) to (7) is included, the content (mol%) is set to 0.00 on the basis of the total number of moles of the vinyl monomer as a constituent unit. 01-20 are preferable, More preferably, it is 0.05-15, Most preferably, it is 0.09-10. Within this range, the expansibility and heat resistance are further improved.

As an organic filler, a well-known organic filler etc. are contained, A polystyrene filler, a polymethylmethacrylate filler, etc. are mentioned.
When an organic filler is included, the content (% by weight) is preferably 0.1 to 20, more preferably 0.3 to 10, particularly preferably 0, based on the total weight of the constituent units of the polymer (P). .5-5.
Examples of the colorant include known dyes and pigments.
When a colorant is included, the content (% by weight) is preferably 0.1 to 20, more preferably 0.3 to 10, particularly preferably 0, based on the total weight of the constituent units of the polymer (P). .5-5.

The volatile liquid (SL) is not particularly limited as long as it does not dissolve the constituent components of the polymer shell (PS), and known ones can be used, such as hydrocarbons, halogenated hydrocarbons, alcohols, ethers, ketones, and the like. Sublimable compounds and the like are included.
Examples of the hydrocarbon include hydrocarbons having 3 to 15 carbon atoms, such as propane, butane, pentane, n-hexane, isohexane, heptane, benzene, toluene, xylene, cyclohexane, cyclopentane, and methylcyclohexane.
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, etc., more preferably hydrocarbons, and particularly preferably pentane, n-hexane, cyclohexane and isohexane.
The content (% by weight) of the volatile liquid (SL) is preferably 1 to 50, more preferably 5 to 20, particularly preferably 10 to 15 based on the weight of the polymer shell (PS).

The heat-expandable microcapsule of the present invention can be produced according to a known method (Japanese Patent Publication No. 42-26524), for example, vinyl monomer, volatile liquid or sublimable solid (SL), and necessary Are mixed with a polymerization initiator, a compound having a reactive group that reacts with the functional groups of the vinyl monomers (2) to (7), a thermoplastic resin, an organic filler and / or a colorant, and this mixture is mixed with a surfactant and / or Alternatively, it may be obtained by a method of dispersing in an aqueous medium containing a dispersion stabilizer followed by suspension polymerization.
The polymerization temperature (° C.) is preferably 50 to 120, more preferably 55 to 90, and particularly preferably 60 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.

Although it does not specifically limit as a polymerization initiator, The initiator soluble in a vinyl 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 is a combined use of a nonionic active agent and a polymeric dispersant.
When a surfactant is used, the amount used (% by weight) is 0.01 to 10 based on the total weight of the vinyl monomer as a constituent unit and the volatile liquid and / or sublimable solid (SL). More preferably, it is 0.05-5, Most preferably, it is 0.1-2.
When using a polymeric dispersant, the amount used is preferably 0.01 to 5, based on the total weight of the vinyl monomer as a constituent unit and the volatile liquid and / or sublimable solid (SL), More preferably, it is 0.02-3, Most preferably, it is 0.03-1.

As the dispersion stabilizer, the same inorganic fine particles (B) described later can be used, and organic fine particles (polystyrene fine particles, polymethyl methacrylate fine particles, polyacrylic acid fine particles, polyepoxide fine particles, etc.) may be used.
Of these, inorganic fine particles (B) are preferable, silica (such as colloidal silica), calcium carbonate, calcium phosphate, aluminum hydroxide, barium carbonate and magnesium hydroxide are particularly preferable, silica is most preferable, and colloidal silk is most preferable. . The dispersion stabilizer is dispersed in an aqueous medium to stabilize the dispersibility of the vinyl monomer and the acrylic polymer (P). After the production of the thermally expandable microcapsule of the present invention, the polymer shell It exists on the outer wall surface of (PS).
When a dispersion stabilizer is used, the amount used (% by weight) is 0.01 to 20 based on the total weight of the vinyl monomer as the constituent unit and the volatile liquid and / or sublimable solid (SL). More preferably, it is 0.1-10, Most preferably, it is 0.5-5.
The surfactant and the dispersion stabilizer may be removed by washing filtration or the like after the production of the thermally expandable microcapsule.

  In addition, you may use various additives as needed, for example, antioxidants (hindert phenol, phosphorus, lactone, etc.), ultraviolet absorbers (benzotriazole, etc.), antibacterial agents (phenyl ether, etc.) and An antistatic agent (polyamide copolymer or the like) can be added.

The volume average particle size (μm) of the thermally expanded microcapsule is preferably 0.1 to 150, more preferably 0.5 to 100, and particularly preferably 1 to 50.
In addition, when used for lightening materials, such as resin, 10-150 micrometers is preferable, More preferably, it is 20-100 micrometers. Moreover, when using for the coating materials for motor vehicles etc., 0.5-100 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).

The aqueous dispersion of thermally expandable microcapsules is not particularly limited as long as the thermally expandable microcapsules are dispersed in an aqueous medium, but as described above, the thermally expandable microcapsules are obtained by suspension polymerization in water. Since it is usual to obtain, the water dispersion obtained by this suspension polymerization can be used as it is. Here, the water dispersion means that the expandable microcapsules are dispersed in a medium containing water as a main component (hereinafter referred to as an aqueous medium), and may contain a surfactant or the like.
Alternatively, the thermally expandable microcapsules obtained by suspension polymerization in water may be once separated into solid and liquid, washed, and then dispersed again in an aqueous medium.
Here, solid-liquid separation means separation of the thermally expandable microcapsule and the aqueous medium. Solid-liquid separation can be performed by a known method, and examples include a method using a centrifuge (centrifugal dehydrator) and a method using a filter. When the thermally expandable microcapsules are dispersed again in the aqueous medium, the above-mentioned surfactant can be used. In addition, a dispersing machine can be used for redispersion. As the disperser, a known disperser can be used. For example, a twin-screw mixer, a planetary mixer (manufactured by Ashizawa Finetech Co., Ltd.), a disperser, a homomixer (manufactured by Special Machinery Co., Ltd.), Examples include Ebara Milder (manufactured by Matsubo Co., Ltd.), various mills (ball mill, basket mill, roller mill, etc. (manufactured by Asada Iron Works Co., Ltd.), etc.).

Various inorganic fine particles (B) can be used depending on the purpose of use of the resin material or the like to which the mixture of the present invention is added. Natural products (B1), modified products of natural products (B2) and Any of synthetic products (including purified products) (B3) may be used. Examples of the shape of the inorganic fine particles (B) include a spherical shape, a needle shape, and a plate shape.
The volume average particle diameter (μm) of the inorganic fine particles (B) is preferably 0.001 to 50, more preferably 0.005 to 10, particularly preferably 0.01 to 5. Within this range, the miscibility with the thermally expandable microcapsules is further improved.
The volume average particle diameter of the inorganic fine particles (B) is measured by a dynamic light scattering method when it is less than 0.1 μm. Here, the dynamic light scattering method is a method of irradiating a particle suspension that is performing Brownian motion with laser light and analyzing the temporal statistical characteristics (eg, time correlation function) of the scattered light, thereby obtaining a particle diameter. It is a method to ask for. It can be measured using a dynamic light scattering particle diameter measuring device {for example, DLS-7000 (manufactured by Otsuka Electronics)} having this measurement principle {light scattering method (25 ° C.)}. On the other hand, in the case of 0.1 μm or more, 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 It is measured using a SALD-1100 model manufactured by Seisakusho.

  Examples of natural products (B1) include limestone (heavy calcium carbonate), quartz, silica (silica), wollastonite, gypsum, asbestos, apatite, magnetite, zeolite, and clay.

  Examples of clay include montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, halloysite, talc, mica and mica.

Examples of the modified natural product (B2) include clay modified with an organic compound (organized clay). Organic clays include clays modified with organic cations (alkyl ammonium ions having an alkyl group with 2 to 70 carbon atoms (hexyl ammonium ion, octyl ammonium ion, 2-ethylhexyl ammonium ion, dodecyl ammonium ion, etc.) In which the cation is exchanged with an organic cation).
There are no particular limitations on the organic method, and any known method can be used.

  Examples of the composite (including purified product) (B3) include metals, metal compounds, other composites (metal composite compounds, non-metal compounds, non-metal composite compounds, etc.), and carbides having organic substances as precursors. It is done.

  As the metal, any metal that is solid at room temperature or higher (20 to 250 ° C.) can be used. In the periodic table of elements, metals in groups 1 to 16 (zinc, aluminum, molybdenum, tungsten, zirconium, Barium, manganese, cobalt, calcium, gold, silver, chromium, titanium, iron, platinum, copper, lead, nickel, etc.), nickel-copper, cobalt-nickel, copper-palladium, iron-bismuth, etc. Also, alloys (solid solution) such as aluminum-magnesium can be used.

  Examples of the metal compound include group 1 to group 16 metal oxides (titanium oxide, zinc oxide, aluminum oxide, chromium oxide, manganese oxide, molybdenum oxide, tungsten oxide, vanadium oxide, tin oxide, oxidation in the periodic table of elements. Iron (including magnetic iron oxide) and indium oxide), metal hydroxides (aluminum hydroxide, gold hydroxide, magnesium hydroxide, etc.), metal sulfides (copper sulfide, sodium sulfide, lead sulfide, nickel sulfide and sulfide) Platinum), metal halides (calcium fluoride, tin fluoride, potassium fluoride, etc.), metal carbides (calcium carbide, titanium carbide, iron carbide, sodium carbide, etc.), metal nitrides (aluminum nitride, chromium nitride, nitriding) Germanium and cobalt nitride), metal carbonates (calcium carbonate (light calcium carbonate), hydrogen carbonate) Lucium, sodium bicarbonate (sodium bicarbonate) and iron carbonate), metal sulfate (aluminum sulfate, cobalt sulfate, sodium hydrogen sulfate, copper sulfate, nickel sulfate, barium sulfate, etc.) and other metal salts (titanate (titanate) Barium, magnesium titanate, potassium titanate, etc.), borate (aluminum borate, zinc borate, etc.), phosphate (calcium phosphate, sodium phosphate, magnesium phosphate, etc.), aluminate (yttrium aluminate (YAG), etc.) ) And nitrates (sodium nitrate, iron nitrate, lead nitrate, etc.)) and the like.

  Other composites include ferrite, zeolite, silver ion supported zeolite, zirconia, alum, lead zirconate titanate (PZT), alumina fiber, cement, zonotlite, MOS (manufactured by Ube Industries), silicon oxide ( Silica, silicate, glass and glass fiber), silicon nitride, silicon carbide and silicon sulfide.

  Examples of the carbide having an organic substance as a precursor include carbon black, carbon nanotube, graphite, activated carbon, bamboo charcoal, charcoal, and fullerene.

An aqueous dispersion of inorganic fine particles (B) can also be used.
As a method for producing an aqueous dispersion of inorganic fine particles (B), it is preferable that (B) is introduced into water and then uniformly dispersed by a disperser. As the disperser, the above dispersers can be used. Moreover, in order to improve the dispersibility of (B), the said surfactant can also be used.
A commercially available aqueous dispersion of inorganic fine particles (B) may be used. Examples thereof include colloidal silica (manufactured by Nissan Chemical Co., Ltd.).

Among these, in order to effectively improve the physical properties (heat resistance, strength, etc.) of the resin material to which the mixture of the present invention is added, the needle-like or plate-like inorganic compound (A) is preferable, specifically Organic clay, wollastonite, acicular potassium titanate (manufactured by DuPont) and zonotlite are preferred.
Further, from the viewpoint of cost reduction of resin materials and the like, calcium carbonate, titanium oxide, silica, clay and the like are particularly preferable.

  Further, by selecting the inorganic fine particles (B), the resin material or the like to which the mixture of the present invention is added can have (a) conductivity, (b) magnetism, (c) piezoelectricity, (d) bactericidal property, and / or (E) Functions such as ultraviolet absorption can also be imparted. To provide these functions, in the case of (a), carbon black, carbon nanotube, metal (silver, copper, gold, platinum, nickel, etc.) and / or indium oxide, etc., in the case of (b) ferrite And / or magnetic iron oxide, etc. In the case of (c), barium titanate and / or PZT, etc., in the case of (d), silver ion-supported zeolite, titanium oxide and / or zinc oxide, etc. It is preferable to use titanium oxide, zinc oxide and / or cerium oxide.

  The content (% by weight) of the inorganic fine particles (B) varies depending on the purpose of use of the resin material to which the mixture of the present invention is added, but is preferably 50 to 1000, more preferably based on the thermally expandable microcapsules. 100-800. Within this range, the effect of improving physical properties and reducing costs due to the inorganic fine particles (B) can be further exhibited together with the effect of reducing the weight by the hollow resin particles.

Mixing of the heat-expandable microcapsule (A) and the inorganic fine particles (B) is carried out by adding (B) or the (B) aqueous dispersion to the (A) aqueous dispersion, or (B) the aqueous dispersion. It is carried out by adding (A) or an aqueous dispersion of (A).
There is no particular limitation on the mixing method, and each of them may be charged all at once or dividedly.
According to the present method, aggregation of the same kind of particles (especially between inorganic fine particles (B)), which is likely to occur in dry mixing, can be alleviated, so that both can be mixed uniformly and inorganic fine particles (B ) Becomes extremely high. As a result, the adhesion of the inorganic fine particles to the surface of the hollow resin particles is high, and a uniform mixture of the hollow resin particles and the inorganic fine particles can be created.

When mixing the heat-expandable microcapsule (A) and the inorganic fine particles (B), the above-described disperser can be used.
The mixing time varies depending on the type of the disperser, the stirring intensity, the mixing amount, and the like, but it is preferable that the mixing time is sufficient for the two to be uniformly mixed. Specifically, it is preferably performed for about 10 minutes to 5 hours, more preferably for 30 minutes to 3 hours.
The manufacturing equipment used is as described above.

In the present invention, solid-liquid separation means separating an aqueous medium from a mixture of an aqueous dispersion of thermally expandable microcapsules and inorganic fine particles (B) or the aqueous dispersion of (A). The method of solid-liquid separation can be performed by a known method. Examples thereof include a method using a centrifuge (centrifugal dehydrator) and a method using a filter.
By solid-liquid separation, a cake (C) of a mixture having a water content of usually 0 to 100% by weight, preferably 0 to 50% by weight is obtained. Depending on the solid-liquid separation method and the like, a cake with a water content exceeding 100% by weight may be obtained. From the viewpoint of improving the expandability, it is necessary to dry and lower the water content to 100% by weight or less. . The cake after solid-liquid separation may be used as it is for the heat expansion treatment described later, or a cake having a reduced water content by drying or a powder (D) having a water content of 0 to 5% by weight may be used. good.
Here, the cake means a lump, and the powder is not lump but powder and has fluidity. Drying means an operation for reducing the water content, and can be performed by a known method. For example, an air dryer, a smooth air dryer, a paddle dryer (manufactured by Nara Machinery Co., Ltd.), a nauter mixer (manufactured by Hosokawa Micron Co., Ltd.), or the like can be used.
The pulverization is an operation of making a lump cake into a powder and can be performed by a known method. For example, various pulverizers, the above-described paddle dryers, nauter mixers, and the like can be used. If a dry pulverizer such as a paddle dryer or Nauta mixer is used, drying and pulverization can be performed simultaneously.
The drying temperature is preferably carried out at a low temperature so that the volatile liquid (SL) does not volatilize. Specifically, the drying temperature is preferably 20 to 100 ° C, more preferably 30 to 80 ° C.
The water content is measured in accordance with JIS K6828-1 “How to determine the non-volatile content of a synthetic resin emulsion”. However, the drying temperature is 50 ° C.

In the present invention, when (C) or (D) is heated and expanded, the thermally expandable microcapsules (A) in (C) or (D) are expanded by heating to form hollow resin particles and inorganic fine particles. It means an operation for obtaining a mixture.
When (D) is used here, the expansion ratio at the time of thermal expansion is increased, and aggregation between particles is reduced, which is preferable.
As a method of heating expansion, a known method can be applied. For example, an air dryer, a smooth air dryer, and a powder mixer (such as Manchuria, a planetary mixer, a paddle dryer, and a nauter mixer) are used. can do.
As heating temperature (degreeC), 90-320 degreeC is preferable, More preferably, it is 100-290, Especially preferably, it is 120-250, Most preferably, it is 130-230.
The heating expansion time is preferably 1 minute to 6 hours, more preferably 3 minutes to 3 hours, and particularly preferably 5 minutes to 1 hour.
Heating can be performed in an atmosphere of air, inert gas (such as nitrogen and argon), or vacuum.

  The heat expansion treatment is preferably performed under mechanical shearing from the viewpoint of uniform expansion and prevention of interparticle adhesion. Here, under mechanical shearing means that (C) or (D) is flowing by applying mechanical energy to (C) or (D). Examples of mechanical energy include stirring and vibration. Specifically, it is preferable to use the above-mentioned powder mixer (Manchuria, planetary mixer, paddle dryer, nauter mixer, etc.), and more preferably continuous powder mixing from the viewpoint of productivity. Machine (paddle dryer, etc.).

The specific gravity (g / cm ³ ) of the mixture is preferably 1.0 to 0.01, more preferably 0.8 to 0.02, and particularly preferably 0.5 to 0.03. Within this range, the resin material or the like to which the present mixture is added can be effectively reduced in weight, and the workability at the time of addition is further improved.
The specific gravity of the hollow resin particles means the specific gravity (apparent density) of the whole particle including the hollow part, and is described in 2. of JIS Z8807-1976 “Solid Specific Gravity Measurement Method”. It is measured according to a measurement method using a specific gravity bottle (liquid; distilled water or methanol).

EXAMPLES Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto. Parts or% means parts by weight or% by weight unless otherwise specified.

The obtained mixture was evaluated by the following method.
<Specific gravity of the mixture>
2. JIS Z8807-1976 “Method of measuring solid specific gravity” The specific gravity was measured according to a measuring method using a specific gravity bottle (liquid; methanol). This specific gravity measurement was repeated 10 times, and the standard deviation of specific gravity was calculated.
<Surface condition of the mixture>
The surface of the hollow resin particles was observed using an electron microscope.
<Dispersion of mixture>
Prepare a square paper with a side of 30 cm on a horizontal table, and when 0.5 part by weight of the mixture is dropped from a position 15 cm high at the center, how much the dropped mixture falls on the square paper. The scattering property was evaluated.

<Example 1>
After uniformly mixing 340 parts of deionized water, 6 parts of 20% colloidal silica aqueous solution (manufactured by Nissan Chemical Industries, Ltd.), 1 part of acetic acid, 10 parts of 10% adipic acid-diethanolamine condensate aqueous solution and 110 parts of sodium chloride To this, 72 parts of acrylonitrile, 15.5 parts of methyl methacrylate, 15.2 parts of methacrylic acid, 25 parts of pentane, 0.5 part of azobisisobutyronitrile and ADK STAB AO50 (manufactured by Asahi Denka Kogyo Co., Ltd.) The solution which consists of was added, and it stirred for 1 minute using the homomixer (ROBOMICS, 10000rpm by special machinery Co., Ltd.), and obtained suspension.
This suspension was transferred to a pressure-resistant reaction vessel and polymerized at 60 ° C. for 20 hours while stirring at a gauge pressure of 0.4 MPa and 300 rpm to obtain an aqueous dispersion of thermally expandable microcapsules.
Add 100 parts of heavy calcium carbonate (manufactured by Sankyo Seimitsu Co., Ltd.) to 100 parts of an aqueous dispersion of thermally expandable microcapsules, and use a disperser (ROBOMICS, 2000 rpm, manufactured by Special Machinery Co., Ltd.), 30 Stir and mix for minutes.
After stirring and mixing for 30 minutes, 500 parts of ion exchange water was added to 150 parts of the mixed solution, and solid-liquid separation was performed using a centrifuge. A cake with a water content of 40% by weight was obtained by solid-liquid separation.
This cake was put into Manban (made by Special Machinery Co., Ltd.) heated to 180 ° C. and subjected to a heat expansion treatment for 15 minutes.
The average specific gravity of the obtained mixture was 0.13, and the standard deviation was 0.014. The mixing amount of the inorganic fine particles (A) was 280% by weight with respect to the thermally expandable microcapsules.
As a result of observing the obtained mixture with an electron microscope, heavy calcium carbonate was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in specific gravity of the mixture and the surface adhesion of heavy calcium carbonate.

<Example 2>
The aqueous dispersion of thermally expandable microcapsules obtained in the same manner as in Example 1 was subjected to solid-liquid separation using a centrifuge. A cake with a water content of 40% by weight was obtained by solid-liquid separation. This cake was dried at 40 ° C. for 15 hours to obtain a powder having a water content of 1.0% by weight. To 20 parts by weight of this powder, 5 parts of a 10% adipic acid-diethanolamine condensate aqueous solution and 75 parts of ion-exchanged water were added and dispersed with a disperser for 30 minutes. To this, 30 parts by weight of heavy calcium carbonate was added and mixed with a disperser for 30 minutes.
150 parts of the mixed solution was subjected to solid-liquid separation using a centrifuge. A cake with a water content of 40% by weight was obtained by solid-liquid separation.
This cake was put into Manban (made by Special Machinery Co., Ltd.) heated to 180 ° C. and subjected to a heat expansion treatment for 15 minutes.
The average specific gravity of the obtained mixture was 0.08, and the standard deviation was 0.014. The mixing amount of the inorganic fine particles (B) was 140% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, heavy calcium carbonate was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in specific gravity of the mixture and the surface adhesion of heavy calcium carbonate.

<Example 3>
The aqueous dispersion of thermally expandable microcapsules obtained in the same manner as in Example 1 was subjected to solid-liquid separation using a centrifuge. A cake with a water content of 40% by weight was obtained by solid-liquid separation. This cake was dried at 40 ° C. for 15 hours to obtain a powder having a water content of 1.0% by weight. To 20 parts by weight of this powder, 5 parts of a 10% adipic acid-diethanolamine condensate aqueous solution and 75 parts of ion-exchanged water were added and dispersed with a disperser for 30 minutes. To this, 110 parts by weight of heavy calcium carbonate was added and mixed with a disperser for 30 minutes.
150 parts of the mixed solution was subjected to solid-liquid separation using a centrifuge. A cake with a water content of 40% by weight was obtained by solid-liquid separation.
This cake was put into Manban (made by Special Machinery Co., Ltd.) heated to 180 ° C. and subjected to a heat expansion treatment for 15 minutes.
The average specific gravity of the obtained mixture was 0.2, and the standard deviation was 0.020. The mixing amount of the inorganic fine particles (B) was 500% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, heavy calcium carbonate was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in specific gravity of the mixture and the surface adhesion of heavy calcium carbonate.

<Example 4>
A mixture was obtained in the same manner as in Example 1 except that 200 parts by weight of a light calcium carbonate aqueous dispersion having a solid content of 30% by weight was used instead of heavy calcium carbonate. An aqueous dispersion of light calcium carbonate is obtained by dispersing 300 parts by weight of light calcium carbonate (Luminous manufactured by Maruo Calcium Co., Ltd.) in 700 parts by weight of water using a homomixer (ROBOMICS, 5000 rpm manufactured by Special Machinery Co., Ltd.) for 30 minutes. Was obtained.
The average specific gravity of the obtained mixture was 0.13, and the standard deviation was 0.016. The mixing amount of the inorganic fine particles (B) was 280% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, light calcium carbonate was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in specific gravity of the mixture and the surface adhesion of light calcium carbonate.

<Example 5>
A mixture was obtained in the same manner as in Example 1 except that titanium oxide was used instead of heavy calcium carbonate.
The average specific gravity of the obtained mixture was 0.11 and the standard deviation was 0.023. The mixing amount of the inorganic fine particles (B) was 280% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, titanium oxide was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in specific gravity of the mixture and the surface adhesion of titanium oxide.

<Example 6>
A mixture was obtained in the same manner as in Example 1 except that talc (manufactured by Achieve Co., Ltd.) was used instead of light calcium carbonate.
The average specific gravity of the obtained mixture was 0.10, and the standard deviation was 0.024. The mixing amount of the inorganic fine particles (B) was 280% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, talc was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no specific gravity variation of the mixture and the surface adhesion of talc.

<Example 7>
A mixture was obtained in the same manner as in Example 1 except that 400 parts by weight of 20% solid colloidal silica (Snowtex AK manufactured by Nissan Chemical Industries, Ltd.) was used instead of light calcium carbonate.
The average specific gravity of the obtained mixture was 0.14, and the standard deviation was 0.017. The mixing amount of the inorganic fine particles (B) was 370% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, silica was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in the specific gravity of the mixture and the surface adhesion of silica.

<Example 8>
A mixture was obtained in the same manner as in Example 1 except that glass powder (manufactured by Achieve Co., Ltd.) was used instead of light calcium carbonate.
The average specific gravity of the obtained mixture was 0.13, and the standard deviation was 0.029. The mixing amount of the inorganic fine particles (B) was 280% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, the glass powder was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in the specific gravity of the mixture and the surface adhesion of the glass powder.

<Example 9>
The cake with a water content of 40% by weight of Example 1 was dried at 40 ° C. for 20 hours using a kanji (manufactured by Special Machinery Co., Ltd.) to obtain a powder with a water content of 2% by weight. A mixture was obtained in the same manner as in Example 1 except that this powder was put into a mixed mixture (made by Special Machinery Co., Ltd.) heated to 180 ° C. and subjected to a heat expansion treatment for 15 minutes.
The average specific gravity of the obtained mixture was 0.12, and the standard deviation was 0.014. The mixing amount of the inorganic fine particles (A) was 280% by weight with respect to the thermally expandable microcapsules.
As a result of observing the obtained mixture with an electron microscope, heavy calcium carbonate was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in specific gravity of the mixture and the surface adhesion of heavy calcium carbonate.

<Example 10>
The cake with a water content of 40% by weight of Example 2 was dried at 50 ° C. for 15 hours using a mixed cake (manufactured by Special Machinery Co., Ltd.) to obtain a powder with a water content of 1% by weight. The mixture was obtained in the same manner as in Example 2 except that the mixture was put into Manchu (heated by Special Machinery Co., Ltd.) heated to 180 ° C. and subjected to a heat expansion treatment for 15 minutes.
The average specific gravity of the obtained mixture was 0.075, and the standard deviation was 0.015. The mixing amount of the inorganic fine particles (B) was 140% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, heavy calcium carbonate was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in specific gravity of the mixture and the surface adhesion of heavy calcium carbonate.

<Example 11>
A mixture was obtained in the same manner as in Example 1 except that the aqueous dispersion of thermally expandable microcapsules was added to the light calcium carbonate aqueous dispersion.
The average specific gravity of the obtained mixture was 0.13, and the standard deviation was 0.015. The mixing amount of the inorganic fine particles (B) was 280% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, light calcium carbonate was uniformly attached to the surface of the hollow resin particles.
When scattering property was evaluated, it was found that there was nothing scattered outside the paper surface and the scattering property was low. The low scattering property can be inferred from the fact that there is no variation in specific gravity of the mixture and the surface adhesion of light calcium carbonate.

<Comparative Example 1>
The aqueous dispersion of thermally expandable microcapsules obtained in the same manner as in Example 1 was subjected to solid-liquid separation using a centrifuge. A cake with a water content of 40% by weight was obtained by solid-liquid separation. 60 parts by weight of heavy calcium carbonate was added to this cake and mixed for 1 hour.
This cake was put into Manban (made by Special Machinery Co., Ltd.) heated to 180 ° C. and subjected to a heat expansion treatment for 15 minutes.
The average specific gravity of the obtained mixture was 0.09, and the standard deviation was 0.26. The mixing amount of the inorganic fine particles (B) was 280% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, many aggregates of calcium carbonate were observed on the surface of the hollow resin particles, and there were portions that were attached and portions that were not attached at all.
As a result of evaluating the scattering property, it was found that many of them scattered outside the paper surface and the scattering property was high. The high scattering property can be inferred from the fact that the specific gravity variation of the mixture is large and the poor surface adhesion of calcium carbonate.

<Comparative example 2>
The aqueous dispersion of thermally expandable microcapsules obtained in the same manner as in Example 1 was subjected to solid-liquid separation using a centrifuge. A cake with a water content of 40% by weight was obtained by solid-liquid separation. This cake was dried at 40 ° C. for 15 hours to obtain a powder having a water content of 1.0% by weight. To this, 60 parts by weight of heavy calcium carbonate was added and mixed for 1 hour.
This cake was put into Manban (made by Special Machinery Co., Ltd.) heated to 180 ° C. and subjected to a heat expansion treatment for 15 minutes.
The average specific gravity of the obtained mixture was 0.12, and the standard deviation was 0.09. The mixing amount of the inorganic fine particles (B) was 280% by weight with respect to the thermally expandable microcapsules (A).
As a result of observing the obtained mixture with an electron microscope, many aggregates of calcium carbonate were observed on the surface of the hollow resin particles, and there were portions that were attached and portions that were not attached at all.
As a result of evaluating the scattering property, it was found that many of them scattered outside the paper surface and the scattering property was high. The high scattering property can be inferred from the fact that the specific gravity variation of the mixture is large and the poor surface adhesion of calcium carbonate.

The mixture of the hollow resin particles and the inorganic fine particles of the present invention can be added to a resin material or the like as a function-imparting agent for reducing weight, improving physical properties, and reducing costs. Specifically, it can be used not only for organic materials such as general-purpose plastic materials, engineering plastic materials, and rubber materials, but also for inorganic materials such as ceramics.

Claims (4)

The inorganic fine particle (B) or the aqueous dispersion of (B) is mixed with the aqueous dispersion of the thermally expandable microcapsule (A), or the thermally expandable microcapsule ( After mixing A) or the aqueous dispersion of (A), solid-liquid separation, or solid-liquid separation and drying are performed to obtain a cake (C) having a water content of 0 to 100% by weight, or (C) To obtain a powder (D) having a water content of 0 to 5% by weight, and (C) or (D) is heated and expanded to form a mixture of hollow resin particles and inorganic fine particles (B). A method for producing a mixture of hollow resin particles and inorganic fine particles. The method for producing a mixture according to claim 1, wherein the inorganic fine particles (B) are at least one selected from the group consisting of calcium carbonate, titanium oxide, silica, talc and mica. The method for producing a mixture according to claim 1 or 2, wherein a mixing amount of the inorganic fine particles (B) is 50 to 1000% by weight with respect to the thermally expandable microcapsules (A). The method for producing a mixture according to any one of claims 1 to 3, wherein the thermal expansion is performed under mechanical shearing.