JP2016169274A - Thermally expansive microsphere and production method therefor and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally expansive microsphere that has small shrinkage degree when heated for a long time and is excellent in heat durability, a production method therefor and a use thereof.SOLUTION: The thermally expansive microsphere of the present invention is a thermally expansive microsphere that is constituted of an outer shell composed of a thermoplastic resin and a foaming agent included in the outer shell and vaporizes by being heated, the thermoplastic resin is constituted of a copolymer obtained by polymerizing polymerizable components, the polymerizable components essentially contain a nitrile-based monomer and a monomer (I) as monomer components and the monomer (I) is at least one kind of monomer selected from acrolein and methacrolein.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermally expandable microsphere, a method for producing the same, and an application thereof.

Thermally expandable microspheres are microencapsulated foaming agents that are vaporized by heating with an outer shell made of a thermoplastic resin, and are also called thermally expandable microcapsules.
Generally, a thermoplastic resin that has a good gas barrier property and softens when heated is used for the polymer that forms the outer shell of the thermally expandable microsphere. When the heat-expandable microspheres are heated, the foaming agent is vaporized, and the expansion force acts on the outer shell, and the elastic modulus of the polymer forming the outer shell decreases rapidly. Rapid expansion occurs. This temperature is referred to as “expansion start temperature”. When the heating temperature is equal to or higher than the expansion start temperature, hollow particles (closed cell bodies) are formed by the above-described expansion phenomenon.

  After that, when the temperature is further increased, the hollow particles further expand as the pressure and volume of the vaporized foaming agent increase. However, the phenomenon that the hollow particles contract at a certain temperature (sagging phenomenon) occurs. . The “sagging phenomenon” is considered to occur when the vaporized foaming agent passes through the outer shell and escapes to the outside, and the expansion force of the foaming agent is inferior to the force acting in the direction of contracting the outer shell. The temperature at which this “sagging phenomenon” occurs is closely related to the heat resistance of the thermally expandable microspheres (hollow particles).

  The heat resistance of thermally expandable microspheres is mainly determined by the balance between the physical properties (softening temperature, melt viscosity, etc.) of the thermoplastic resin constituting the outer shell and the vapor pressure of the substance constituting the foaming agent. . A typical example of examining the heat resistance of thermally expandable microspheres is measurement of the maximum expansion temperature using a thermomechanical analyzer. In this measurement, thermally expandable microspheres are placed in a container, and the heating temperature is continuously increased from around room temperature at a rate of temperature increase of about 5 to 10 ° C./min, and the displacement of the height is continuously measured. Here, the temperature at which the displacement of the height of the thermally expandable microspheres in the container starts is the expansion start temperature, and the temperature at which the height is maximum is the maximum expansion temperature. In this case, when the heating temperature reaches a temperature exceeding the maximum expansion temperature, the “sagging phenomenon” as a whole of the thermally expandable microspheres (hollow particles) occurs, but this “sagging phenomenon” occurs up to a higher temperature region. No heat-expandable microspheres are generally said to have excellent heat resistance.

  By the way, the above-mentioned “sagging phenomenon” mainly focuses on the relationship between the heating temperature and the “sagging phenomenon”, and the influence of the heating time is not considered much. Actually, even if the temperature of the heat-expandable microspheres is lower than the maximum expansion temperature, the heat-expandable microspheres once in an expanded state are kept heated for several tens of minutes or longer. In many cases, a “sagging phenomenon” occurs in a sphere (hollow particle) and the hollow particle contracts. Such a “sagging phenomenon” is caused by a time factor rather than a temperature factor. Thus, even if the heating time is long, the “sagging phenomenon” hardly occurs. It can be said that the thermal durability is excellent.

  As described above, the heat-expandable microspheres have the property of being expanded by heating to form lightweight hollow particles, so they are used in a wide range of fields such as designability-imparting agents, functionality-imparting agents, and lightening agents. It has been. On the other hand, conventional heat-expandable microspheres exhibit excellent expandability when the heating time is relatively short, and the desired design, porosity, lightness, heat insulation, sound absorption, impact Although sufficient effects such as absorbability can be obtained, if the heating time is long, the thermal durability is not sufficient, so that the “sag phenomenon” described above occurs and the hollow particles shrink and the desired There was a problem that the effect of was not sufficiently obtained.

  In Patent Document 1, a polymerizable component having a polymerizable monomer having two or more polymerizable double bonds and a monomer capable of forming a homopolymer having a high glass transition temperature is polymerized. Thermally expandable microspheres have been proposed that contain an outer shell made of the copolymer and a volatile expansion agent that becomes gaseous at a temperature below the softening point of the copolymer. It is described that a sphere becomes a microballoon (hollow particle) having excellent thermal expansibility and excellent thermal durability after thermal expansion. However, even these thermally expandable microspheres cannot be said to have sufficient thermal durability when heated for a longer time, and further improvement in thermal durability has been demanded.

JP 05-285376 A

  An object of the present invention is to provide a thermally expandable microsphere having a small degree of shrinkage when heated for a long time and having excellent thermal durability, a method for producing the same, and a use thereof.

  As a result of intensive studies to solve the above problems, the present inventors have solved the above problems when the polymerizable component essentially contains a nitrile monomer and a specific monomer component. And reached the present invention.

That is, the thermally expandable microsphere according to the present invention is a thermally expandable microsphere composed of an outer shell made of a thermoplastic resin and a foaming agent encapsulated therein and vaporized by heating. The plastic resin is composed of a copolymer obtained by polymerizing a polymerizable component, and the polymerizable component essentially contains a nitrile monomer and a monomer (I) as monomer components, Monomer (I) is at least one monomer selected from acrolein and methacrolein.
The weight ratio of the monomer (I) is preferably 0.0001 to 0.1 part by weight with respect to 100 parts by weight of the nitrile monomer. The weight ratio of the nitrile monomer is preferably 30 to 99% by weight with respect to the monomer component. The nitrile monomer preferably contains acrylonitrile and / or methacrylonitrile.
The thermally expandable microsphere preferably contains at least one component (A) selected from toluene, acetonitrile, propanenitrile and isobutyronitrile. Moreover, it is preferable that the weight ratio of the said component (A) is 0.0001 to 0.1 weight% with respect to the said thermally expansible microsphere.

The method for producing thermally expandable microspheres according to the present invention is a method for producing thermally expandable microspheres comprising an outer shell made of a thermoplastic resin and a foaming agent encapsulated therein and vaporized by heating. And dispersing the oily mixture containing the foaming agent and the polymerizable component in an aqueous dispersion medium, and polymerizing the polymerizable component, wherein the polymerizable component is a nitrile monomer as a monomer component. And monomer (I), and the monomer (I) is at least one monomer selected from acrolein and methacrolein.
The oily mixture preferably contains at least one component (A) selected from toluene, acetonitrile, propanenitrile and isobutyronitrile.

The hollow particles of the present invention are obtained by heating and expanding the thermally expandable microspheres and / or the thermally expandable microspheres obtained by the production method.
The composition of the present invention includes the thermally expandable microspheres, at least one granular material selected from the thermally expandable microspheres obtained by the production method and the hollow particles, and a base material component.
The molded product of the present invention is formed by molding the composition.

The heat-expandable microspheres of the present invention have a small degree of shrinkage when heated for a long time and are excellent in thermal durability.
The method for producing thermally expandable microspheres of the present invention can efficiently produce thermally expandable microspheres that have a small degree of shrinkage when heated for a long time and are excellent in thermal durability.
Since the hollow particles of the present invention are formed by expanding the thermally expandable microspheres and / or the thermally expandable microspheres obtained by the above production method, the degree of shrinkage when heated for a long time is small, and the heat durability is improved. Excellent.
The composition of the present invention is excellent in heat durability because it contains at least one granular material selected from the above-mentioned thermally expandable microspheres, the thermally expandable microspheres obtained by the above production method, and the above hollow particles, and is molded. Thus, a lightweight molded product can be obtained.
Since the molded product of the present invention is formed by molding the above composition, it is lightweight.

It is the schematic which shows an example of a thermally expansible microsphere. It is the schematic which shows an example of a hollow particle.

[Thermal expandable microspheres]
As shown in FIG. 1, the thermally expandable microsphere of the present invention is composed of an outer shell (shell) 11 made of a thermoplastic resin and a foaming agent (core) 12 that is contained in the shell and vaporizes when heated. These are thermally expandable microspheres. The thermally expandable microsphere has a core-shell structure, and the thermally expandable microsphere exhibits thermal expandability (property that the entire microsphere expands by heating) as a whole microsphere. The thermoplastic resin is obtained by polymerizing a polymerizable component.

The polymerizable component is a component that becomes a thermoplastic resin that forms the outer shell of the thermally expandable microsphere by polymerization. The polymerizable component is a component which essentially includes a monomer component and may contain a crosslinking agent.
The monomer component means a radical polymerizable monomer having one polymerizable double bond and is a component capable of addition polymerization. The crosslinking agent means a radically polymerizable monomer having a plurality of polymerizable double bonds, and is a component that introduces a bridge structure into the thermoplastic resin.

The polymerizable component essentially comprises a nitrile monomer.
Examples of the nitrile monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile and the like. These nitrile monomers may be used alone or in combination of two or more.

  The weight ratio of the nitrile monomer is preferably 30 to 99% by weight, more preferably 33 to 99% by weight, still more preferably 40 to 98% by weight, particularly preferably 50%, based on the monomer component. ~ 98 wt%. When the weight ratio is 30 to 99% by weight, the heat-expandable microspheres obtained have excellent thermal durability.

The nitrile monomer preferably includes acrylonitrile and / or methacrylonitrile, more preferably includes methacrylonitrile, and further preferably includes acrylonitrile and methacrylonitrile.
When the nitrile monomer contains acrylonitrile (AN) and methacrylonitrile (MAN), the weight ratio of acrylonitrile and methacrylonitrile (AN / MAN) is not particularly limited, but preferably 10/90 to 90 / 10, more preferably 30/70 to 80/20, still more preferably 45/55 to 75/25. If the AN and MAN weight ratio is less than 10/90, the gas barrier property may be lowered. On the other hand, if the AN and MAN weight ratio exceeds 90/10, sufficient expansion ratio may not be obtained.

  The polymerizable component further requires the monomer (I). Monomer (I) is at least one monomer selected from acrolein and methacrolein. The weight ratio of the monomer (I) is preferably 0.0001 to 0.1 parts by weight, more preferably 0.0001 to 0.05 parts by weight, more preferably 100 parts by weight of the nitrile monomer. Preferably it is 0.0002-0.01 weight part, Most preferably, it is 0.0002-0.005 weight part. Although the detailed mechanism is unknown, when the polymerizable component contains the monomer (I) in the above specific range, the heat-expandable microspheres obtained have excellent thermal durability.

  Further, the combination of the nitrile monomer and the monomer (I) that are essentially included in the polymerizable component is not particularly limited. For example, a combination of acrylonitrile and methacrylonitrile with acrolein and methacrolein, acrylonitrile And a combination of methacrylonitrile and acrolein, a combination of acrylonitrile and methacrylonitrile and methacrolein, a combination of acrylonitrile and acrolein, a combination of methacrylonitrile and methacrolein, and the like. Among these, acrylonitrile and a combination of methacrylonitrile and methacrolein are preferable.

  Here, the thermal durability in the present invention will be described. The heat durability in the present invention means that the “sagging phenomenon” of the heat-expandable microspheres (hollow particles) is suppressed when the heating time is long. Specifically, even if the “sagging phenomenon” does not occur or the “sagging phenomenon” occurs, the degree of contraction of the thermally expandable microspheres (hollow particles) is small and the expansion is closer to the maximum expansion. Means maintaining state.

In the present invention, the thermal durability index of the thermally expandable microsphere is evaluated as TD (%). A specific method for measuring TD (%) will be described in Examples described later. TD (%) is evaluated at the maximum expansion temperature of the thermally expandable microsphere, and how long the thermally expandable microsphere that has reached the maximum expansion state by heating maintains its volume expansion state after being continuously heated. This is the value shown. In addition, the said maximum expansion temperature means the maximum expansion temperature determined by the method demonstrated by the [measurement of the maximum expansion temperature and the true specific gravity at the time of maximum expansion] of the Example mentioned later. The TD (%) of the thermally expandable microsphere is preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. The upper limit of TD (%) is 100%. When the TD (%) of the thermally expandable microsphere is less than 30%, the thermal durability is insufficient.
The heat resistance in the present invention means that the heat-expandable microsphere can be used at a high temperature and exhibits excellent expandability when the heating time is relatively short.

The polymerizable component may contain a monomer other than the nitrile monomer and monomer (I) as the monomer component.
The monomer other than the nitrile monomer and the monomer (I) is not particularly limited. For example, a vinyl halide monomer such as vinyl chloride; a vinylidene halide monomer such as vinylidene chloride; Vinyl ester monomers such as vinyl acetate, vinyl propionate and vinyl butyrate; carboxyl group-containing monomers such as (meth) acrylic acid, ethacrylic acid, crotonic acid and cinnamic acid; maleic acid, itaconic acid, Carboxylic anhydride monomers such as fumaric acid; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl ( (Meth) acrylate, phenyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate (Meth) acrylic acid ester monomers such as rate, benzyl (meth) acrylate and 2-hydroxyethyl (meth) acrylate; (meth) acrylamide monomers such as acrylamide, substituted acrylamide, methacrylamide and substituted methacrylamide Maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide; styrene monomers such as styrene and α-methylstyrene; ethylene unsaturated monoolefin monomers such as ethylene, propylene and isobutylene; vinyl Vinyl ether monomers such as methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl ketone monomers such as vinyl methyl ketone; N-vinyl monomers such as N-vinyl carbazole and N-vinyl pyrrolidone; Vinyl naphthalene List salt etc. be able to. In the carboxyl group-containing monomer, some or all of the carboxyl groups may be neutralized during polymerization or after polymerization. In addition, (meth) acryl means acryl or methacryl. These monomers may be used alone or in combination of two or more. Among these, the polymerizable component preferably contains at least one selected from vinylidene chloride, a carboxyl group-containing monomer, a (meth) acrylic acid ester monomer, and a (meth) acrylamide monomer. When the polymerizable component contains vinylidene chloride, gas barrier properties are improved. When the polymerizable component contains a carboxyl group-containing monomer, heat resistance and solvent resistance are improved. When the polymerizable component contains a (meth) acrylic acid ester monomer, the expansion behavior can be easily controlled. When the polymerizable component contains a (meth) acrylamide monomer, the heat resistance is improved.

  When the polymerizable component contains vinylidene chloride, the weight ratio of vinylidene chloride is preferably 0.1 to 69% by weight, more preferably 0.1 to 65% by weight, based on the monomer component. When the polymerizable component contains a (meth) acrylic acid ester monomer together with vinylidene chloride, the weight ratio of vinylidene chloride is preferably 0.1 to 65% by weight, more preferably 0, based on the monomer component. 0.1 to 62% by weight, and the weight ratio of the (meth) acrylic acid ester monomer is preferably 0.1 to 10% by weight, more preferably 0.1 to 6%, based on the monomer component. % By weight.

  When the polymerizable component includes a carboxyl group-containing monomer, the weight ratio of the carboxyl group-containing monomer is preferably 0.1 to 69% by weight, more preferably 0.1 to 0.1% by weight with respect to the monomer component. It is 65% by weight, more preferably 0.1 to 59% by weight, and particularly preferably 0.1 to 49% by weight. When the polymerizable component includes a monomer that reacts with the carboxyl group of the carboxyl group-containing monomer together with the carboxyl group-containing monomer, the heat resistance is further improved, and the expansion performance at high temperatures is improved. Examples of the monomer that reacts with the carboxyl group of the carboxyl group-containing monomer include, for example, N-methylol (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth). Acrylate, vinyl glycidyl ether, propenyl glycidyl ether, glycidyl (meth) acrylate, glycerin mono (meth) acrylate, 4-hydroxybutyl acrylate glycidyl ether, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2 -Hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, p-hydroxystyrene, etc. can be mentioned. The weight ratio of the monomer that reacts with the carboxyl group of the carboxyl group-containing monomer is preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, and more preferably, with respect to the monomer component. Preferably it is 0.1 to 2 weight%, Most preferably, it is 0.1 to 1 weight%.

  When the polymerizable component contains a (meth) acrylic acid ester monomer, the weight ratio of the (meth) acrylic acid ester monomer is preferably 0.1 to 69 weight with respect to the monomer component. %, More preferably 0.1 to 65% by weight, still more preferably 0.1 to 59% by weight, particularly preferably 0.1 to 49% by weight.

As described above, the polymerizable component may contain a crosslinking agent in addition to the monomer component. By polymerizing using a cross-linking agent, in the thermally expandable microspheres obtained, a decrease in the retention rate (encapsulation retention rate) of the encapsulated foaming agent during thermal expansion is suppressed, and effective thermal expansion can be achieved. it can.
The crosslinking agent is not particularly limited. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, allyl methacrylate, triacryl formal, triallyl isocyanate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) ) Acrylate, triethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, PEG # 200 di (meth) acrylate, PEG # 400 di (meth) acrylate, PEG # 600 di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethyl Propane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, glycerin di (meth) acrylate, dimethylol-tricyclodecane di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) ) Acrylate, dipentaerythritol hexa (meth) acrylate, neopentyl glycol acrylic acid benzoate, trimethylolpropane acrylic acid benzoate, 2-hydroxy-3-acryloyloxypropyl (meth) acrylate, hydroxypivalic acid Neopentyl glycol di (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) ) Acrylate, polytetramethylene glycol di (meth) acrylate, phenyl glycidyl ether acrylate hexamethylene diisocyanate urethane prepolymer, phenyl glycidyl ether acrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene A diisocyanate urethane prepolymer, a pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, etc. can be mentioned. These crosslinking agents may be used alone or in combination of two or more.

  Although there is no limitation in particular about the quantity of a crosslinking agent, Preferably it is 0-5 weight part with respect to 100 weight part of monomer components, More preferably, it is 0.1-2 weight part, More preferably, it is 0.3- The amount is 1.5 parts by weight, particularly preferably 0.5 to 1.0 part by weight.

  The foaming agent is a component that is vaporized by heating, and is encapsulated in an outer shell made of a thermoplastic resin of thermally expandable microspheres. The whole shows a property of swelling by heating.

  The foaming agent is not particularly limited as long as it is a substance that is vaporized by heating. For example, propane, (iso) butane, (iso) pentane, (iso) hexane, (iso) heptane, (iso) octane, ( C3-C13 hydrocarbons such as (iso) nonane, (iso) decane, (iso) undecane, (iso) dodecane, (iso) tridecane; (iso) hexadecane, (iso) eicosane, etc. Hydrocarbons of 20 or less; pseudocumene, petroleum ether, hydrocarbons such as petroleum fractions such as normal paraffin and isoparaffin having an initial boiling point of 150 to 260 ° C. and / or a distillation range of 70 to 360 ° C .; methyl chloride, methylene chloride, Halogenated hydrocarbons having 1 to 12 carbon atoms such as chloroform and carbon tetrachloride; Fluorine-containing compounds such as hydrofluoroether; Silanes having an alkyl group having 1 to 5 carbon atoms such as lamethylsilane, trimethylethylsilane, trimethylisopropylsilane, trimethyl-n-propylsilane; azodicarbonamide, N, N′-dinitrosopentamethylenetetramine, 4,4 ′ -A compound etc. which generate | occur | produces gas by thermally decomposing by heating, such as oxybis (benzenesulfonyl hydrazide), are mentioned. These foaming agents may be used alone or in combination of two or more. The foaming agent may be linear, branched or alicyclic, and is preferably aliphatic.

  A foaming agent is a substance that is vaporized by heating, but if a substance having a boiling point below the softening point of a thermoplastic resin is included as a foaming agent, a vapor pressure sufficient for expansion at the expansion temperature of the thermally expandable microspheres is obtained. It is preferable because it can be generated and a high expansion ratio can be imparted. In this case, as the foaming agent, a substance having a boiling point lower than the softening point of the thermoplastic resin and a substance having a boiling point higher than the softening point of the thermoplastic resin may be included.

The thermally expandable microsphere preferably contains at least one selected from toluene, acetonitrile, propanenitrile and isobutyronitrile (hereinafter, these may be referred to as component (A)). Although the detailed mechanism is unknown, the component (A) has some effect on the thermoplastic resin constituting the outer shell of the thermally expandable microsphere, and has the effect of improving the thermal durability of the thermally expandable microsphere. It is an ingredient to have. Since the component (A) is a substance that is vaporized by heating, it is a component included in the concept of the foaming agent in the present invention. However, the foaming agent excluding the component (A) in the present invention has no effect of improving the thermal durability of the thermally expandable microsphere. It suffices that the component (A) is contained in the entire thermally expandable microsphere, and all of the component (A) may be contained in the outer shell, and all of the component (A) is contained in the outer shell. It may be in a state where a part thereof is enclosed in the outer shell and a part thereof is contained in the outer shell. Among the component (A), the thermally expandable microsphere preferably contains at least one selected from toluene and propanenitrile, and more preferably contains toluene. When the heat-expandable microspheres contain a specific amount of the component (A), the resulting heat-expandable microspheres are further improved in thermal durability.
The weight ratio of the component (A) is preferably 0.0001 to 0.1% by weight, more preferably 0.0001 to 0.05% by weight, and still more preferably 0.0002 to 0.1% by weight with respect to the thermally expandable microspheres. 0.01% by weight, particularly preferably 0.0002 to 0.005% by weight. When the weight ratio is less than 0.0001% by weight, the effect of improving the heat durability may not be sufficiently obtained. When the weight ratio exceeds 0.1% by weight, the expansion performance of the thermally expandable microspheres is deteriorated. There is.

  The encapsulating rate of the foaming agent is defined as the percentage of the weight of the foaming agent encapsulated in the thermally expandable microspheres relative to the weight of the thermally expandable microspheres. The encapsulating rate of the foaming agent is not particularly limited, but is preferably 1 to 50% by weight, more preferably 2 to 45% by weight, still more preferably 5 to 40% by weight, based on the weight of the thermally expandable microspheres. Particularly preferably, it is 10 to 30% by weight. The encapsulating rate of the foaming agent when the thermally expandable microspheres include the component (A) is the components (A) and components (A) and (components) contained in the thermally expandable microspheres with respect to the weight of the thermally expandable microspheres. It means the percentage of the total weight with the blowing agent excluding A).

  The average particle size of the thermally expandable microsphere is not particularly limited, but is preferably 1 to 100 μm, more preferably 2 to 80 μm, still more preferably 3 to 60 μm, and particularly preferably 5 to 50 μm. When the average particle diameter is smaller than 1 μm, the expansion performance of the thermally expandable microsphere may be lowered. On the other hand, when the average particle diameter is larger than 100 μm, aggregates are generated in the process of producing the thermally expandable microspheres, and the thermally expandable microspheres may not be obtained efficiently.

  The coefficient of variation CV of the particle size distribution of the heat-expandable microspheres is not particularly limited, but is preferably 45% or less, more preferably 40% or less, and even more preferably 30% or less. The variation coefficient CV is calculated by the following calculation formulas (1) and (2).

（式中、ｓは粒子径の標準偏差、＜ｘ＞は平均粒子径、ｘ_ｉはｉ番目の粒子径、ｎは粒子の数である。）

(Wherein, s is the standard deviation of the particle size, <x> is an average particle size, x _i is the i-th particle diameter, n is the number of particles.)

The expansion start temperature (T _s ) of the thermally expandable microsphere is not particularly limited, but is preferably 60 to 200 ° C, more preferably 65 to 190 ° C, still more preferably 70 to 180 ° C, and particularly preferably 80 to 170 ° C. It is.
Although there is no limitation in particular about the maximum expansion temperature ( _Tmax ) of a thermally expansible microsphere, Preferably it is 80-350 degreeC, More preferably, it is 100-300 degreeC, More preferably, it is 120-280 degreeC, Most preferably, it is 140- 250 ° C. If the maximum expansion temperature of the thermally expandable microsphere is less than 80 ° C., sufficient heat resistance may not be obtained.

  The heat-expandable microspheres obtained by the present invention have a small degree of shrinkage when heated for a long time and are excellent in heat durability, so that injection molding, extrusion molding, kneading molding, calendar molding, blow molding, compression molding, vacuum It can be used for molding such as molding and thermoforming. Further, the thermally expandable microspheres of the present invention can be used by being mixed with a paste-like material such as a vinyl chloride paste or a liquid composition such as an EVA emulsion, an acrylic emulsion, or a solvent-type binder. It is effective to use these heat-expandable microspheres mixed with a vehicle paint composition that requires heating for a long time until the final product form is obtained.

The maximum expansion ratio of the heat-expandable microsphere is not particularly limited, but is preferably 3 times or more, more preferably 10 times or more, still more preferably 20 times or more, particularly preferably 30 times or more, and further preferably 50 times or more. Most preferably, it is 70 times or more. On the other hand, the upper limit of the maximum expansion ratio is preferably 200 times.
When the pressure resistance of the hollow particles obtained by heating and expanding the thermally expandable microspheres is required, the maximum expansion ratio of the thermally expandable microspheres is preferably set in order to maintain the thickness of the outer shell of the hollow particles. Is 3 times or more, and a preferable upper limit is 100 times. If the maximum expansion ratio is less than 3 times, a sufficient lightening effect may not be obtained. When the maximum expansion ratio exceeds 100 times, pressure resistance may be insufficient.
When heat-expandable microspheres are mixed with a resin composition and the resin composition is expanded by heating to obtain a lightweight product, the maximum expansion ratio is preferably 20 times or more, and the upper limit is preferably 200 times. is there. If the maximum expansion ratio is less than 20 times, a sufficient lightening effect may not be obtained. When the maximum expansion ratio exceeds 200 times, it may cause surface roughness in a molded article or the like.
The thermally expandable microspheres of the present invention can be produced by a production method by suspension polymerization described in detail below, but are not limited to this production method. For example, the interfacial polymerization method, reverse phase emulsification method, emulsion weight It may be possible to manufacture it legally.

[Production method and use of thermally expandable microspheres]
The method for producing thermally expandable microspheres of the present invention comprises dispersing an oily mixture containing a polymerizable component containing the specific monomer component described above in detail and a foaming agent in an aqueous dispersion medium, and the polymerizable component. It is a method including a step of polymerizing (hereinafter also referred to as a polymerization step).
In the polymerization step, it is preferable to polymerize the polymerizable component in the presence of the polymerization initiator using an oily mixture containing a polymerization initiator.

Although there is no limitation in particular as a polymerization initiator, The peroxide, an azo compound, etc. which are used very generally can be mentioned.
Examples of the peroxide include peroxydicarbonates such as diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, dibenzylperoxydicarbonate; lauroyl peroxide Diacyl peroxides such as benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxyketals such as 2,2-bis (t-butylperoxy) butane; cumene hydroperoxide, t-butyl Hydroperoxides such as hydroperoxides; Dialkyl peroxides such as dicumyl peroxide and di-t-butyl peroxide; t-hexylperoxypivalate, t-butyl It can be exemplified helper peroxy esters such as oxy isobutyrate.

Examples of the azo compound include 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4- Dimethylvaleronitrile), 2,2'-azobis (2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), etc. Can be mentioned.
These polymerization initiators may be used alone or in combination of two or more. As the polymerization initiator, an oil-soluble polymerization initiator soluble in the monomer component is preferable. The polymerization initiator may be used by adding it to the oily mixture in advance before dispersing the oily mixture in the aqueous dispersion medium, or adding it to the aqueous suspension after the oily mixture is dispersed in the aqueous dispersion medium. May be.

  Although there is no limitation in particular about the compounding quantity of a polymerization initiator, Preferably it is 0.05-10 weight part with respect to 100 weight part of polymeric components, More preferably, it is 0.1-8 weight part, More preferably Is 0.2 to 5 parts by weight.

In the polymerization step, the oily mixture may further contain a chain transfer agent and the like.
In the production method of the present invention, an aqueous suspension in which an oily mixture is dispersed in an aqueous dispersion medium is prepared, and a polymerizable component is polymerized.
The aqueous dispersion medium is a medium mainly composed of water such as ion-exchanged water in which the oily mixture is dispersed, and may further contain an alcohol such as methanol, ethanol or propanol, or a hydrophilic organic solvent such as acetone. Good. The hydrophilicity in the present invention means that it can be arbitrarily mixed with water. Although there is no limitation in particular about the usage-amount of an aqueous dispersion medium, it is preferable to use 100-1000 weight part aqueous dispersion medium with respect to 100 weight part of polymeric components.

  The aqueous dispersion medium may further contain an electrolyte. Examples of the electrolyte include sodium chloride, magnesium chloride, calcium chloride, sodium sulfate, magnesium sulfate, ammonium sulfate, and sodium carbonate. These electrolytes may be used alone or in combination of two or more. Although there is no limitation in particular about content of an electrolyte, it is preferable to contain 0.1-50 weight part with respect to 100 weight part of aqueous dispersion media.

  The aqueous dispersion medium is a polyalkyleneimine having a molecular weight of 1000 or more having at least one structure in which an alkyl group substituted with a hydrophilic functional group selected from a carboxylic acid (salt) group and a phosphonic acid (salt) group is bonded to a nitrogen atom Water-soluble 1,1-substituted compounds having a structure in which a hydrophilic functional group selected from a hydroxyl group, a carboxylic acid (salt) group and a phosphonic acid (salt) group and a hetero atom are bonded to the same carbon atom, At least one selected from potassium chromate, alkali metal nitrite, metal (III) halide, boric acid, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble vitamin Bs and water-soluble phosphonic acids (salts) The water-soluble compound may be contained. In addition, the water solubility in this invention means the state which melt | dissolves 1g or more per 100g of water.

  The amount of the water-soluble compound contained in the aqueous dispersion medium is not particularly limited, but is preferably 0.0001 to 1.0 part by weight, more preferably 0.0003 to 100 parts by weight of the polymerizable component. 0.1 parts by weight, more preferably 0.001 to 0.05 parts by weight. If the amount of the water-soluble compound is too small, the effect of the water-soluble compound may not be sufficiently obtained. Moreover, when there is too much quantity of a water-soluble compound, a polymerization rate may fall or the residual amount of the polymeric component which is a raw material may increase.

The aqueous dispersion medium may contain a dispersion stabilizer and a dispersion stabilization auxiliary agent in addition to the electrolyte and the water-soluble compound.
The dispersion stabilizer is not particularly limited. For example, colloidal silica, colloidal calcium carbonate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, ferric hydroxide, calcium sulfate, barium sulfate, calcium oxalate, metasilicic acid. Calcium, calcium carbonate, barium carbonate, magnesium carbonate, calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, etc. phosphates, calcium pyrophosphate, aluminum pyrophosphate, pyrophosphates such as zinc pyrophosphate, difficulties such as alumina sol The dispersion stabilizer of a water-soluble inorganic compound can be mentioned. These dispersion stabilizers may be used alone or in combination of two or more, and the type thereof is appropriately selected in consideration of the particle diameter of the resulting heat-expandable microspheres, dispersion stability during polymerization, and the like. Of these, tricalcium phosphate, magnesium pyrophosphate obtained by the metathesis method, calcium pyrophosphate, and colloidal silica are preferable.

The blending amount of the dispersion stabilizer is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the polymerizable component.
The dispersion stabilizing aid is not particularly limited, and examples thereof include a polymer type dispersion stabilizing aid, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant. Mention may be made of activators. These dispersion stabilizing aids may be used alone or in combination of two or more, and are appropriately selected in consideration of the particle diameter of the resulting heat-expandable microspheres, dispersion stability during polymerization, and the like.

Examples of the polymer type dispersion stabilizing aid include, for example, a condensation product of diethanolamine and an aliphatic dicarboxylic acid, gelatin, polyvinyl pyrrolidone, methyl cellulose, polyethylene oxide, polyvinyl alcohol and the like.
The blending amount of the dispersion stabilizing auxiliary agent is not particularly limited, but is preferably 0.0001 to 5 parts by weight, more preferably 0.0003 to 2 parts by weight with respect to 100 parts by weight of the polymerizable component.

  The aqueous dispersion medium is prepared, for example, by blending water, such as ion-exchanged water, with an electrolyte, a water-soluble compound, a dispersion stabilizer, a dispersion stabilization auxiliary agent, and the like as necessary. The pH of the aqueous dispersion medium at the time of polymerization is appropriately determined depending on the type of the water-soluble compound, the dispersion stabilizer, and the dispersion stabilization aid. When colloidal silica is used as the dispersion stabilizer, the pH of the aqueous dispersion medium during polymerization is preferably 2 to 7, more preferably 2 to 6.5, still more preferably 2 to 6, and particularly preferably 2 to 4. .

In the production method of the present invention, polymerization may be carried out in the presence of sodium hydroxide, sodium hydroxide and zinc chloride.
In the production method of the present invention, an oily mixture is suspended and dispersed in an aqueous dispersion medium so that spherical oil droplets having a predetermined particle diameter are prepared.

As a method for suspending and dispersing the oily mixture, for example, a method of stirring with a homomixer (for example, manufactured by Primix) or a method of using a static dispersion device such as a static mixer (for example, manufactured by Noritake Engineering Co., Ltd.). And general dispersion methods such as a membrane suspension method and an ultrasonic dispersion method.
Next, suspension polymerization is started by heating the dispersion in which the oily mixture is dispersed as spherical oil droplets in the aqueous dispersion medium. During the polymerization reaction, it is preferable to stir the dispersion, and the stirring may be performed so gently as to prevent, for example, floating of the monomer and sedimentation of the thermally expandable microspheres after polymerization.

  Although superposition | polymerization temperature is freely set by the kind of polymerization initiator, Preferably it is 30-100 degreeC, More preferably, it controls in the range of 40-90 degreeC. During the polymerization reaction, the reaction temperature may be changed stepwise or may be a single step. The time for maintaining the reaction temperature is preferably about 1 to 20 hours. Although there is no limitation in particular about the superposition | polymerization initial stage pressure, it is 0-5 Mpa in gauge pressure, More preferably, it is the range of 0.1-3 Mpa.

  After the completion of the polymerization reaction, if desired, the dispersion stabilizer is decomposed with hydrochloric acid or the like, and the resulting product (thermally expandable microspheres) is isolated from the dispersion by operations such as suction filtration, centrifugation, and centrifugal filtration. . Furthermore, the obtained thermally expandable microsphere-containing water-containing cake can be washed with water and dried to obtain thermally expandable microspheres.

The hollow particles of the present invention can be produced by heating and expanding the thermally expandable microspheres of the present invention and / or the thermally expandable microspheres obtained by the production method of the present invention.
The hollow particles are composed of an outer shell made of a thermoplastic resin and a hollow portion surrounded by the outer shell. The hollow particles are (almost) spherical and have a hollow portion corresponding to a large cavity inside. If the shape of the hollow particles is exemplified by familiar articles, a soft tennis ball can be mentioned.

  The hollow part is (substantially) spherical and is in contact with the inner surface of the outer shell. The hollow portion is basically filled with a gas obtained by vaporizing the foaming agent, and a part of the foaming agent may be in a liquefied state. Further, all or part of the foaming agent may be replaced with other gas such as air. Usually, the hollow part is preferably one large hollow part, but there may be a plurality of hollow parts.

  Although there is no limitation in particular about the average particle diameter of a hollow particle, Preferably it is 1-1000 micrometers, More preferably, it is 5-800 micrometers, More preferably, it is 10-500 micrometers. Further, the coefficient of variation CV of the particle size distribution of the hollow particles is not particularly limited, but is preferably 45% or less, more preferably 40% or less, and further preferably 30% or less.

Although there is no limitation in particular about the true specific gravity of a hollow particle, Preferably it is 0.005-0.3, More preferably, it is 0.010-0.25, More preferably, it is 0.015-0.20. When the true specific gravity of the hollow particles is less than 0.005, the pressure resistance may be lowered. On the other hand, when the true specific gravity of the hollow particles is larger than 0.3, the effect of lowering the specific gravity is lowered. Therefore, when preparing a composition using the hollow particles, the amount added is large, which is uneconomical. There is.
As shown in FIG. 2, the hollow particles may be further composed of a fine particle filler attached to the outer surface of the outer shell. Hereinafter, the hollow particles to which the fine particle filler is attached may be referred to as “fine particle-attached hollow particles”. The term “adhesion” as used herein may simply be the state (4) in which the fine particle fillers (4 and 5) are adsorbed on the outer surface of the outer shell (2) of the hollow particle (1). This means that the thermoplastic resin constituting the outer shell may be melted by heating, and the fine particle filler may sink into the outer surface of the outer shell of the hollow particles and be fixed (5). The particle shape of the fine particle filler may be indefinite or spherical.

  The weight ratio of the fine particle filler to the hollow particles (fine particle filler / hollow particles) is not particularly limited, but is preferably 90/10 to 60/40, more preferably 85/15 to 65/35, and even more preferably. Is 80 / 20-70 / 30. When the fine particle filler / hollow particles (weight ratio) is larger than 90/10, the true specific gravity of the fine particle-attached hollow particles is increased, and the effect of lowering the specific gravity may be reduced. On the other hand, when the fine particle filler / hollow particles (weight ratio) is smaller than 60/40, the true specific gravity of the fine particle-adhered hollow particles is low, and handling such as dusting may be deteriorated.

The true specific gravity of the fine particle-attached hollow particles is not particularly limited, but is preferably 0.01 to 0.5, more preferably 0.03 to 0.4, still more preferably 0.05 to 0.35, Most preferably, it is 0.07-0.30. When the true specific gravity of the fine particle-attached hollow particles is less than 0.01, the pressure resistance may be lowered. On the other hand, when the true specific gravity of the fine particle-adhered hollow particles is greater than 0.5, the effect of reducing the specific gravity is reduced. Sometimes.
The average particle size of the fine particle filler is appropriately selected and is not particularly limited, but is preferably 0.001 to 30 μm, more preferably 0.005 to 25 μm, and still more preferably 0.01 to 20 μm.

The ratio between the average particle size of the fine particle filler and the average particle size of the fine particle-attached hollow particles (average particle size of the fine particle filler / average particle size of the fine particle-attached hollow particles) is preferably from the viewpoint of adhesion of the fine particle filler. 1 or less, more preferably 0.8 or less, and still more preferably 0.6 or less.
Various particles can be used as the fine particle filler, and any of inorganic and organic materials may be used. Examples of the shape of the fine particle main body include a spherical shape, a needle shape, and a plate shape.

Examples of inorganic substances constituting the fine particle filler include limestone (heavy calcium carbonate), quartz, silica (silica), wollastonite, gypsum, apatite, magnetite, zeolite, clay (montmorillonite, saponite, hectorite, beidellite, and steven. Minerals such as site, nontronite, vermiculite, halloysite, talc, mica, mica, etc .; in the periodic table of elements, group 1-16 metal oxides (titanium oxide, zinc oxide, aluminum oxide, manganese oxide, oxidation) Molybdenum, tungsten oxide, vanadium oxide, tin oxide, iron oxide (including magnetic iron oxide), indium oxide, etc., metal hydroxide (aluminum hydroxide, gold hydroxide, magnesium hydroxide, etc.), metal carbonate (carbonic acid) Calcium (light calcium carbonate), hydrogen carbonate cal , Sodium hydrogen carbonate (bicarbonate), iron carbonate, etc., metal sulfates (aluminum sulfate, cobalt sulfate, sodium hydrogen sulfate, copper sulfate, nickel sulfate, barium sulfate, etc.), 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.), nitrate (sodium nitrate, iron nitrate, lead nitrate, etc.) )) And the like.
Inorganic substances constituting the fine particle filler are also synthetic calcium carbonate, ferrite, zeolite, silver ion supported zeolite, zirconia, alum, lead zirconate titanate, alumina fiber, cement, zonotlite, silicon oxide (silica, silicate, glass, (Including glass fiber), silicon nitride, silicon carbide, silicon sulfide, carbon black, carbon nanotube, graphite, activated carbon, bamboo charcoal, charcoal, fullerene, and the like.

Organic substances constituting the fine particle filler are sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, nitrocellulose, hydroxypropyl cellulose, sodium alginate, polyvinyl alcohol, polyvinyl pyrrolidone, sodium polyacrylate, carboxyvinyl polymer, polyvinyl methyl ether, ( Examples thereof include (meth) acrylic resin, polyamide resin, nylon resin, silicon resin, urethane resin, polyethylene resin, and fluorine resin.
The inorganic substance or organic substance constituting the fine particle filler may be treated with a surface treating agent such as fatty acid, resin acid, urethane compound, fatty acid ester, or may be untreated.

The method for producing the hollow particles is not particularly limited as long as it is a method for heating and expanding the thermally expandable microspheres, and may be either a dry heating expansion method or a wet heating expansion method.
Examples of the dry heating expansion method include an internal injection method described in Japanese Patent Application Laid-Open No. 2006-213930. This internal injection method includes a step of injecting a gas fluid containing thermally expandable microspheres through a gas introduction pipe provided with a dispersion nozzle at the outlet and installed inside the hot air flow and injecting from the dispersion nozzle (injection step); , The step of causing the gaseous fluid to collide with a collision plate installed downstream of the dispersion nozzle and dispersing the thermally expandable microspheres in the hot air flow (dispersion step); It is a dry-type heat expansion method including a step (expansion step) of heating and expanding above the expansion start temperature in a hot air flow. The internal injection method is preferable because hollow particles having uniform physical properties can be obtained regardless of the type of thermoplastic resin constituting the outer shell of the thermally expandable microspheres as a raw material. As another dry heating expansion method, there is a method described in Japanese Patent Application Laid-Open No. 2006-96963.
Examples of the wet heating expansion method include the method described in Japanese Patent Application Laid-Open No. 62-201231.

  Examples of the method for producing the fine particle-attached hollow particles include a step of mixing thermally expandable microspheres and a particulate filler (mixing step), and starting the expansion of the thermally expandable microspheres using the mixture obtained in the mixing step. There can be mentioned a production method including a step of heating to a temperature equal to or higher than the temperature to expand the thermally expandable microspheres and attaching the fine particle filler to the outer surface of the outer shell (attachment step).

  Since the hollow particles of the present invention have a small degree of shrinkage when heated for a long time and are excellent in heat durability, injection molding, extrusion molding, kneading molding, calendar molding, blow molding, compression molding, vacuum molding, thermoforming, etc. It can be used for molding. The hollow particles of the present invention can also be used by being mixed with a paste-like material such as a vinyl chloride paste or a liquid composition such as an EVA emulsion, an acrylic emulsion, or a solvent-type binder. It is effective to mix and use in a vehicle paint composition that requires heating for a long time before it is made into a final product form.

[Composition, molded product and use thereof]
The composition of the present invention comprises at least one granular material selected from the thermally expandable microspheres of the present invention, the thermally expandable microspheres obtained by the production method of the present invention, and the hollow particles of the present invention, and a base component. including. There is no limitation in particular as a base material component, What is necessary is just an inorganic component and / or an organic component. Hereinafter, at least one granular material selected from the thermally expandable microspheres of the present invention, the thermally expandable microspheres obtained by the production method of the present invention, and the hollow particles of the present invention may be simply referred to as granular materials.
The inorganic component is not particularly limited. For example, ordinary portland cement, early-strength cement, alumina cement, blast furnace slag cement, fly ash cement and the like; blast furnace slag, electric furnace oxidation slag, electric furnace reduction slag, etc. Slag; limes such as quicklime and slaked lime; titania, alumina, zirconia, silica, magnesia, zircon, barium zirconate, cordierite, lead titanate, barium titanate, mullite, zinc oxide, tin oxide, silicon carbide, silicon nitride And ceramics such as ferrite, and the like. These inorganic components may be used alone or in combination of two or more.

  The organic component is not particularly limited. For example, natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber, Rubbers such as silicon rubber, acrylic rubber, urethane rubber, fluoro rubber, ethylene-propylene-diene rubber (EPDM); thermosetting resins such as epoxy resin, phenol resin, unsaturated polyester resin, polyurethane; polyethylene wax, paraffin wax, etc. Waxes: ethylene-vinyl acetate copolymer (EVA), polyethylene, modified polyethylene, polypropylene, modified polypropylene, modified polyolefin, polyvinyl chloride (PVC), acrylic resin, thermoplastic polyurethane, acrylonitrile-styrene Polymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polystyrene (PS), polyamide resin (nylon 6, nylon 66, etc.), modified polyamide, polycarbonate, polyethylene terephthalate (PET), polybutylene terephthalate Thermoplastic resins such as (PBT), polyacetal (POM), polyphenylene sulfide (PPS), polyphenylene ether (PPE), and modified polyphenylene ether; ionomer resins such as ethylene ionomer, urethane ionomer, styrene ionomer, and fluorine ionomer; Thermoplastic elastomers such as olefin elastomers, styrene elastomers, polyester elastomers; polylactic acid (PLA), cellulose acetate, PBS, P A, bioplastics such as starch resin; sealing materials such as modified silicone, urethane, polysulfide, acrylic, silicone, polyisobutylene, butyl rubber; urethane, ethylene-vinyl acetate copolymer, vinyl chloride Examples of the organic component include acrylic and acrylic paint components, and these organic components may be used alone or in combination of two or more.

The composition of this invention can be prepared by mixing these base material components and a granular material. Moreover, the composition obtained by mixing a base material component and a granular material can be further mixed with another base material component to obtain the composition of the present invention.
The weight ratio of the granular material is preferably 0.1 to 70 parts by weight, more preferably 0.5 to 65 parts by weight, and still more preferably 1 to 60 parts by weight with respect to 100 parts by weight of the base material component.
The mixing method is not particularly limited, but it is preferable to mix with a kneader, a roll, a mixing roll, a mixer, a single screw kneader, a twin screw kneader, a multi screw kneader or the like.
The composition of the present invention includes, as necessary, binders such as hydroxypropylmethylcellulose, methylcellulose, hydroxyethylcellulose, carboxylmethylcellulose, polyvinyl alcohol, polyethylene terephthalate, and the like; Further, it may contain a dispersant such as polyalcohol.
Examples of the use of the composition of the present invention include a molding composition, a coating composition, a clay composition, a fiber composition, an adhesive composition, and a powder composition.

The molded product of the present invention is obtained by molding the composition described above. Examples of the molded article of the present invention include molded articles such as molded articles and coating films. In the molded product of the present invention, various physical properties such as lightness, porosity, sound absorption, heat insulation, low thermal conductivity, low dielectric constant, design, impact absorption, and strength are improved.
A ceramic filter or the like can be obtained by further firing a molded product containing an inorganic substance as a base component.

Examples of the present invention will be specifically described below. The present invention is not limited to these examples. In the following Examples and Comparative Examples, “%” means “% by weight” and “parts” means “parts by weight” unless otherwise specified.
About the thermally expansible microsphere, the hollow particle, the composition, and the molding which were mentioned in the following examples and comparative examples, the physical property was measured in the following way, and performance was evaluated further. Hereinafter, the heat-expandable microsphere may be referred to as “microsphere” for simplicity.

(Measurement of particle size and particle size distribution)
A laser diffraction / scattering particle size distribution measuring device (Microtrac ASVR Nikkiso Co., Ltd.) was used to measure the particle size and particle size distribution of the microspheres. The volume-based cumulative 50% particle size (D50) was taken as the average particle size. The volume-based cumulative particle diameter means a particle diameter with respect to a predetermined ratio of a distribution obtained by accumulating all the particles in the order of volume from the smaller side.

[Measurement of moisture content of microspheres]
As a measuring apparatus, a Karl Fischer moisture meter (MKA-510N type, manufactured by Kyoto Electronics Industry Co., Ltd.) was used for measurement.

[Measurement of true specific gravity of microspheres and hollow particles]
The true specific gravity of the microspheres and hollow particles was measured by the following measuring method.
The true specific gravity was measured by an immersion method (Archimedes method) using isopropyl alcohol in an atmosphere having an environmental temperature of 25 ° C. and a relative humidity of 50%.
Specifically, the volumetric flask having a capacity of 100 cc was emptied and dried, and the weight of the volumetric flask (WB ₁ ) was weighed. After the weighed volumetric flask was accurately filled with isopropyl alcohol to the meniscus, the weight (WB ₂ ) of the volumetric flask filled with 100 cc of isopropyl alcohol was weighed.

Further, the volumetric flask with a capacity of 100 cc was emptied and dried, and the weight of the volumetric flask (WS ₁ ) was weighed. The weighed volumetric flask was filled with about 50 cc of particles, and the weight (WS ₂ ) of the volumetric flask filled with the particles was weighed. Then, the weight (WS ₃ ) after accurately filling the meniscus with isopropyl alcohol so that bubbles do not enter into the volumetric flask filled with particles was weighed. Then, the obtained WB ₁ , WB ₂ , WS ₁ , WS ₂ and WS ₃ were introduced into the following formula, and the true specific gravity (d) of the particles was calculated.
d = {(WS ₂ −WS ₁ ) × (WB ₂ −WB ₁ ) / 100} / {(WB ₂ −WB ₁ ) − (WS ₃ −WS ₂ )}
Above, the true specific gravity was calculated using microspheres and hollow particles as particles.

[Measurement of maximum expansion temperature and true specific gravity at maximum expansion]
A flat box with a bottom of 12 cm in length, 13 cm in width, and 9 cm in height is made of aluminum foil, and 1.0 g of dried microspheres are uniformly placed therein, and this box is set at a predetermined temperature. The microspheres were heated and expanded for a predetermined time in an oven. Specifically, the temperature of the gear-type oven was set as 5 ° C. intervals in the range of 50 to 300 ° C., and the heating time was set as 1 minute intervals in the range of 1 to 10 minutes. The true specific gravity of the microspheres (hollow particles) heated and expanded at each temperature and time is measured according to the above measurement method, and the temperature showing the smallest true specific gravity value among them is the maximum expansion temperature (T _max ). And the value of the true specific gravity was defined as the true specific gravity d _max during maximum expansion.

[Evaluation of thermal durability TD]
The thermal durability TD was evaluated at the maximum expansion temperature obtained above. Specifically, by the same method as described above, the true specific gravity d _s of hollow particles obtained by heating and expanding microspheres at the maximum expansion temperature for 60 minutes is measured, and the thermal durability TD (%) is calculated by the following equation. did.
Thermal durability TD (%) = (d _max / d _s ) × 100

[Example A1]
In 600 g of ion-exchanged water, 80 g of colloidal silica whose active ingredient amount is 20% by weight, 1.0 g of polyvinylpyrrolidone and carboxymethylated polyethyleneimines (CMPEI; substituted alkyl group: —CH ₂ COONa, substitution rate: 80 %, Weight average molecular weight: 50,000), and then the pH of the resulting mixture was adjusted to 2.8 to 3.2 to prepare an aqueous dispersion medium.
Separately, 160 g of acrylonitrile, 120 g of methacrylonitrile, 20 g of methyl methacrylate, 0.0045 g of methacrolein, 1.0 g of ethylene glycol dimethacrylate, 35 g of isobutane as a foaming agent, 25 g of isopentane, and 0. An oily mixture was prepared by mixing 0030 g, 0.0030 g of propanenitrile and 3.0 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as an initiator. The aqueous dispersion medium and the oily mixture were mixed, and the resulting mixture was dispersed with a homomixer (Primix Co., TK homomixer) at a rotational speed of 11000 rpm for 2 minutes to prepare a suspension. The suspension was transferred to a pressure reactor having a capacity of 1.5 liters and purged with nitrogen. Then, the initial reaction pressure was 0.50 MPa, and the polymerization reaction was carried out at a polymerization temperature of 55 ° C. for 20 hours while stirring at 80 rpm. After the polymerization, the polymerization product was filtered and dried to obtain microspheres. The physical properties of the obtained microspheres were evaluated, and the results are shown in Table 1.

[Examples A2 to A9 and Comparative Examples A1 to A9]
In Examples A2 to A9 and Comparative Examples A1 to A9, microspheres were obtained in the same manner as in Example 1 except that the oily mixture was changed to those shown in Tables 1 to 4. Furthermore, the physical property was evaluated and the result was shown to Tables 1-4.

In Tables 1 to 4, the following abbreviations are used.
PVP: Polyvinylpyrrolidone CMPEI: Carboxymethylated polyethyleneimine / Na salt (substituted alkyl group: —CH ₂ COONa, substitution rate: 80%, weight average molecular weight: 50,000)
EDTA: ethylenediaminetetraacetic acid / 4Na salt AN: acrylonitrile MAN: methacrylonitrile MA: methyl acrylate MMA: methyl methacrylate IBX: isobornyl methacrylate VCl ₂ : vinylidene chloride MAA: methacrylic acid MAM: methacrylamide EDMA: ethylene glycol di Methacrylate TMP: Trimethylolpropane trimethacrylate V-65: 2,2'-azobis (2,4-dimethylvaleronitrile)
OPP: Di-2-ethylhexyl peroxydicarbonate (purity 70% by weight)

  As shown in Tables 1 to 4, the thermally expandable microspheres of the present invention have a small true specific gravity at the time of maximum expansion and excellent expansion ratio, and the degree of shrinkage is small even after heating at the maximum expansion temperature for 60 minutes. It is clear that the thermal durability is excellent.

[Example B1]
(Preparation of unexpanded PVC coating)
25 parts by weight of polyvinyl chloride (PVC) (manufactured by Shin-Daiichi Vinyl Chloride Co., Ltd.), 50 parts by weight of DINP (manufactured by Shin Nippon Rika Co., Ltd.) A compound was prepared by adding 24 parts by weight of calcium (manufactured by Bihoku Powder Chemical Co., Ltd.). The prepared compound was coated on a Teflon (registered trademark) sheet with a thickness of 1.5 mm and gelled by heating at 100 ° C. for 10 minutes in a gear oven to obtain an unexpanded PVC coating.

(Production of expanded PVC coating)
The unexpanded PVC coating film was heated in a gear-type oven set to the maximum expansion temperature of the microspheres of Example A1 for 60 minutes to obtain an expanded PVC coating film.
Measured unexpanded PVC coating film having a specific gravity _{(d A)} and the expansion PVC coating specific gravity _{(d B)} respectively, before and after foaming specific gravity reduction rate _{(= (d A -d B)} × 100 / d A) Calculated and evaluated for lightness. The results are shown in Table 5. The greater the specific gravity reduction rate, the better the physical properties such as weight reduction, cushioning properties, elasticity, and impact strength. The specific gravity of the PVC coating film was measured by an immersion method using a precision hydrometer AX200 manufactured by Shimadzu Corporation.

[Example B2, Comparative Example B1 and Comparative Example B2]
In Example B2, Comparative Example B1 and Comparative Example B2, the microspheres used are changed to those shown in Table 5, respectively, and the temperature at which the unexpanded PVC coating is heated is changed to the maximum expansion temperature of the microspheres used. Except for the above, an expanded PVC coating film was obtained in the same manner as in Example B1. About the obtained expanded PVC coating film, specific gravity reduction rate was calculated | required like Example B1, and the result was shown in Table 5.

  From the results in Table 5, it is clear that the expanded PVC coating obtained from the thermally expandable microspheres of the present invention has very excellent performance in physical properties such as weight reduction, cushioning properties, elasticity, and impact strength. is there.

  The heat-expandable microspheres of the present invention have a small degree of shrinkage when heated for a long time and are excellent in thermal durability. Therefore, it is useful in applications intended to improve designability, porosity, weight reduction, heat insulation, sound absorption, shock absorption and the like. The method for producing thermally expandable microspheres of the present invention can efficiently produce the above thermally expandable microspheres.

11 Outer shell made of thermoplastic resin 12 Foaming agent 1 Hollow particle (fine particle-attached hollow particle)
2 Outer shell 3 Hollow part 4 Fine particle filler (adsorbed state)
5 Fine particle filler (indented and fixed state)

Claims (11)

A thermally expandable microsphere composed of an outer shell made of a thermoplastic resin and a foaming agent contained therein and vaporized by heating;
The thermoplastic resin is composed of a copolymer obtained by polymerizing a polymerizable component,
The polymerizable component essentially contains a nitrile monomer and a monomer (I) as a monomer component,
The monomer (I) is at least one monomer selected from acrolein and methacrolein.
Thermally expandable microspheres.   The thermally expansible microsphere of Claim 1 whose weight ratio of the said monomer (I) is 0.0001-0.1 weight part with respect to 100 weight part of said nitrile monomers.   The thermally expandable microsphere according to claim 1 or 2, wherein a weight ratio of the nitrile monomer is 30 to 99% by weight with respect to the monomer component.   The thermally expandable microsphere according to any one of claims 1 to 3, wherein the nitrile monomer includes acrylonitrile and / or methacrylonitrile.   The thermally expandable microsphere according to any one of claims 1 to 4, wherein the thermally expandable microsphere includes a component (A) that is at least one selected from toluene, acetonitrile, propanenitrile, and isobutyronitrile. .   The thermally expansible microsphere of Claim 5 whose weight ratio of the said component (A) is 0.0001 to 0.1 weight% with respect to the said thermally expansible microsphere. A method for producing thermally expandable microspheres comprising an outer shell made of a thermoplastic resin and a foaming agent encapsulated therein and vaporized by heating,
Dispersing an oily mixture containing the foaming agent and a polymerizable component in an aqueous dispersion medium, and polymerizing the polymerizable component;
The polymerizable component essentially contains a nitrile monomer and a monomer (I) as a monomer component,
The monomer (I) is at least one monomer selected from acrolein and methacrolein.
A method for producing thermally expandable microspheres.   The method for producing thermally expandable microspheres according to claim 7, wherein the oily mixture contains a component (A) which is at least one selected from toluene, acetonitrile, propanenitrile and isobutyronitrile.   Hollow particles obtained by heating and expanding the thermally expandable microspheres according to any one of claims 1 to 6 and / or the thermally expandable microspheres obtained by the production method according to any one of claims 7 to 8. .   It is chosen from the thermally expansible microsphere in any one of Claims 1-6, the thermally expansible microsphere obtained by the manufacturing method in any one of Claims 7-8, and the hollow particle of Claim 9. A composition comprising at least one particulate material and a base component.   A molded article obtained by molding the composition according to claim 10.

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