JP7394263B2 - Thermally expandable microspheres and their uses - Google Patents

Description

The present invention relates to thermally expandable microspheres and their uses.

Thermal-expandable microspheres having a structure in which the outer shell is made of thermoplastic resin and a blowing agent is encapsulated therein are generally called thermally-expandable microspheres (thermal-expandable microcapsules). Thermally expandable microspheres are microspheres that have the characteristic of expanding when subjected to heat treatment.
These thermally expandable microspheres are used in a wide range of applications, for example, thermally expandable microspheres are incorporated into a base material. Due to the heat treatment applied during molding, the thermally expandable microspheres expand at the same time as molding, making it possible not only to reduce the weight of the molded product but also to impart design properties, cushioning properties, etc. to the molded product.
In order to ensure the expansion function of thermally expandable microspheres, the thermoplastic resin used for their outer shells usually needs to have gas barrier properties. Such thermally expandable microspheres may have outer shells made of vinylidene chloride copolymers, acrylonitrile copolymers, acrylic copolymers, etc., and blowing agents such as isobutane or isopentane may be used. A method using mainly hydrocarbons has been disclosed (Patent Document 1).

US Patent No. 3,615,972

However, the thermally expandable microspheres disclosed in Patent Document 1 do not exhibit biodegradability and may cause marine pollution problems due to microplastics.
An object of the present invention is to provide thermally expandable microspheres that have good expansion performance and exhibit biodegradability, and uses thereof.

As a result of extensive studies, the present inventors discovered that the above-mentioned problems could be solved by thermally expandable microspheres having specific performance, and thus arrived at the present invention.
That is, the present invention provides thermally expandable microspheres that include an outer shell containing a thermoplastic resin and a foaming agent that is encapsulated in the outer shell and vaporizes when heated, and that is measured in accordance with JIS K6950:2000. Thermal expandable microspheres have a biodegradability (De1) of more than 0% for 5 days.

The thermally expandable microspheres of the present invention preferably satisfy at least one of the following 1) to 5).
1) The thermoplastic resin is a polymer of a polymerizable component containing a monomer (A), and the monomer (A) has one polymerizable carbon-carbon double bond, and an ester bond and /or has an ether bond.
2) The monomer (A) is a compound having 5 or more oxygen atoms in the molecule.
3) The monomer (A) has the following group (a1) in the molecule.
Group (a1): a group containing a linear structure moiety and/or a branched structure moiety and having two or more carbon atoms 4) The polymerizable component is a nitrile monomer, a carboxyl group other than monomer (A) It further includes a monomer (B) which is at least one selected from group-containing monomers and (meth)acrylic acid ester monomers other than monomer (A).
5) The degree of biodegradation (De2) for 5 days measured in accordance with JIS K6950:2000 after immersion in acetonitrile for 24 hours is more than 0%.

The hollow particles of the present invention are expanded bodies of the above thermally expandable microspheres.
The fine particle-attached hollow particles of the present invention are composed of the hollow particles described above and fine particles adhered to the outer surface of the outer shell portion of the hollow particles.

The composition of the present invention includes at least one selected from the above thermally expandable microspheres, the above hollow particles, and the above fine particle-attached hollow particles, and a base material component.
The molded article of the present invention is formed by molding the above composition.

The thermally expandable microspheres of the present invention have good expansion performance and are biodegradable.
Since the hollow particles of the present invention are obtained using the above thermally expandable microspheres as raw materials, they have a low specific gravity and are biodegradable.
The microparticle-attached resin hollow particles of the present invention are obtained using the above thermally expandable microspheres as raw materials, and therefore have a low specific gravity and exhibit biodegradability.
Since the composition of the present invention contains at least one selected from the above thermally expandable microspheres, the above hollow particles, and the above fine particle-attached empty particles, a lightweight molded article can be obtained.
The molded article of the present invention is lightweight.

FIG. 2 is a schematic diagram showing an example of thermally expandable microspheres. FIG. 2 is a schematic diagram showing an example of resin hollow particles to which fine particles are attached.

The present invention will be explained below.
In this specification, the numerical range represented by "~" means a numerical range that includes the numbers before and after "~" as the lower limit and upper limit. If a plurality of lower limit values and a plurality of upper limit values are listed separately, any lower limit value and any upper limit value may be selected to form a range connected by "~".

[Thermally expandable microspheres]
The heat-expandable microspheres of the present invention include an outer shell containing a thermoplastic resin and a blowing agent that is encapsulated in the outer shell and vaporizes when heated. Thermally expandable microspheres exhibit thermal expandability (the property that the entire microsphere expands upon heating).
As shown in FIG. 1, the thermally expandable microspheres of the present invention have a core-shell structure composed of an outer shell 6 and a foaming agent (core) 7.

In the thermally expandable microspheres of the present invention, the outer shell contains a thermoplastic resin.
The thermoplastic resin forming the outer shell is preferably a polymer obtained by polymerizing a polymerizable component since it can have good expansion performance.
The polymerizable component is a component that is essentially a monomer component and may contain a crosslinking agent. The monomer component means a monomer having one (radical) polymerizable carbon-carbon double bond, and is a component capable of addition polymerization. Further, the crosslinking agent refers to a monomer having at least two (radically) polymerizable carbon-carbon double bonds, and is a component that introduces a crosslinking structure into a thermoplastic resin.

When the polymerizable component has one carbon-carbon double bond in the molecule and contains a monomer (A) having an ester bond and/or an ether bond, both swelling performance and biodegradability can be achieved. It is preferable.
The total number of ester bonds and ether bonds that the monomer (A) has is not particularly limited, but is preferably 1 to 35, and furthermore, (1) 1 to 30, (2) 1 to 25. (3) 1 to 20 pieces, (4) 1 to 15 pieces, (5) 2 to 15 pieces, (6) 2 to 10 pieces, (7) 2 to 8 pieces, (8) 2 to 6 pieces, (9) Preferably in the order of 2 to 4 (the larger the number in parentheses is, the more preferable it is).
When the monomer (A) has an ester bond or an ether bond, the number of each bond is preferably within the numerical range of the total number of the above-mentioned ester bonds and ether bonds.
Furthermore, the monomer (A) may be a (meth)acrylic acid ester derivative.

The number of oxygen atoms that the monomer (A) has in the molecule is not particularly limited, but is preferably 5 or more. When the number of oxygen atoms is 5 or more, biodegradability tends to improve. The number of oxygen atoms is (1) 5 to 40, (2) 5 to 35, (3) 6 to 35, (4) 6 to 30, (5) 7 to 30, (6) 7 ~25 pieces, (7) 7 to 20 pieces, and (8) 8 to 20 pieces are preferable in this order (the larger the number in parentheses is, the more preferable it is).
The monomer (A) may have a phosphorus atom and/or a sulfur atom in its molecule, or may not have a phosphorus atom and/or a sulfur atom.

The monomer (A) may have the following group (a1). It is preferable that the monomer (A) has the group (a1) because the stretchability of the thermoplastic resin during softening is improved and the expansion performance is improved. Monomer (A) belongs to the monomer components explained above.
Group (a1): a group containing a linear structure moiety and/or a branched structure moiety and having two or more carbon atoms

When the monomer (A) has a group (a1), the number of carbon atoms in the group (a1) is not particularly limited, but is preferably 2 or more, such as (1) 2 to 150, (2 ) 2 to 125 pieces, (3) 3 to 85 pieces, (4) 4 to 65 pieces, (5) 5 to 65 pieces, and (6) 5 to 45 pieces are preferable in this order (as the number in parentheses increases, preferable.).
When the monomer (A) has a group (a1), the group (a1) may not have a polymerizable carbon-carbon double bond, but may have a polymerizable carbon-carbon double bond. Good too. In order to achieve the effects of the present invention, the group (a1) preferably does not have a polymerizable carbon-carbon double bond.
When the monomer (A) has an ester bond and a group (a1), an oxygen atom other than the carbonyl moiety in the ester bond is preferably bonded to the group (a1).

The straight chain structure moiety and/or the branched structure moiety that the group (a1) has has a carbon atom. The number of carbon atoms in the linear structure part and/or the branched structure part is not particularly limited, but from the viewpoint of achieving the effects of the present invention, it is preferably 2 to 150, and furthermore, (1) 2 to 120, (2) 2 to 80 pieces, (3) 2 to 60 pieces, (4) 3 to 60 pieces, (5) 4 to 60 pieces, (6) 4 to 40 pieces, (7) 5 to 40 pieces Preferable (the larger the number in parentheses is, the more preferable it is).
The linear structure moiety and/or the branched structure moiety that the group (a1) has may contain a carbon atom and further an oxygen atom.

The group (a1) may have at least one selected from an alkoxy group, a phenoxy group, a carboxyl group, and a hydroxyl group. It is preferable that the group (a1) has at least one selected from an alkoxy group, a phenoxy group, a carboxyl group, and a hydroxyl group because heat resistance is improved. The number of carbon atoms in the alkoxy group is preferably 1 to 20.

Monomer (A) may have at least one selected from oxyalkylene structural moieties and hydroxycarboxylic acid structural moieties in its molecule.
The number of carbon atoms in the oxyalkylene structural moiety is not particularly limited, but is preferably 2 to 4, preferably 2 to 3, in order to achieve the effects of the present invention.
The number of carbon atoms in the hydroxycarboxylic acid structural part is not particularly limited, but from the viewpoint of achieving the effects of the present invention, it is preferably 1 to 15, more preferably 1 to 10, and even more preferably is 2 to 8, particularly preferably 2 to 6.
When the monomer (A) has at least one type selected from an oxyalkylene structural moiety and a hydroxycarboxylic acid structural moiety in the molecule, it is preferable that the oxyalkylene structural moiety is present in the group (a1).

When the monomer (A) has at least one type selected from oxyalkylene structure moieties and hydroxycarboxylic acid structure moieties in its molecule, the number of constituent units of the oxyalkylene structure and the number of constituent units of the hydroxycarboxylic acid structure The total number of is not particularly limited, but is preferably 1 to 30, and furthermore, (1) 1 to 20, (2) 2 to 20, (3) 2 to 15, and (4) 3 to 30. 15 pieces, and (5) 3 to 10 pieces are preferable (the larger the number in parentheses is, the more preferable it is). In addition, in the present invention, when the total number of structural units of the oxyalkylene structure and the number of structural units of the hydroxycarboxylic acid structure is 2 or more, the total number of structural units is equal to the average number of structural units of the above structural part. means the sum.
In addition, when the monomer (A) has an oxyalkylene structure moiety or a hydroxycarboxylic acid structure moiety in its molecule, the number of constituent units of each structure is the number of constituent units of the above-mentioned oxyalkylene structure and the hydroxycarboxylic acid structure moiety. It is preferable that the numerical value range is the total number of structural units of the structure.

Monomer (A) may be an alkylene oxide adduct and/or a lactone adduct. It is preferable that the monomer (A) is an alkylene oxide adduct and/or a lactone adduct, since biodegradability is improved.
The number of moles of alkylene oxide added in the monomer (A) is not particularly limited, but it is preferably within the same numerical range as the number of constituent units of oxyalkylene explained above. In the present invention, the number of moles of alkylene oxide added means the average number of moles of alkylene oxide added, and the number of moles of lactone added means the average number of moles of lactone added.
Further, the number of carbon atoms in the alkylene oxide is not particularly limited, but is preferably 2 to 4, preferably 2 to 3.

The number of moles of lactone added in the monomer (A) is not particularly limited, but is preferably 1 to 15, more preferably (1) 1 to 10, (2) 2 to 10, (3) 2 to 8. , (4) 2 to 6, and (5) 2 to 4 are preferable in this order (the larger the number in parentheses is, the more preferable it is). In the present invention, the number of moles of lactone added means the average number of moles of lactone added.
The number of carbon atoms in the lactone is not particularly limited, but is preferably 4 to 15, more preferably 5 to 10, even more preferably 6 to 9, particularly preferably 6 (caprolactone). .

Examples of the monomer (A) include methoxypolyethylene glycol mono(meth)acrylate, methoxypolypropylene glycol mono(meth)acrylate, methoxypolybutylene glycol mono(meth)acrylate, and methoxypolyethylene glycol-polypropylene glycol mono(meth)acrylate. , methoxypolyethylene glycol-polybutylene glycol mono(meth)acrylate, methoxypolypropylene glycol-polybutylene glycol mono(meth)acrylate, octylpolyethylene glycol mono(meth)acrylate, lauroxypolyethylene glycol mono(meth)acrylate, stearoxypolyethylene glycol Alkoxypolyoxyalkylene mono(meth)acrylates such as mono(meth)acrylate; Phenoxypolyoxyalkylene mono(meth)acrylates such as phenoxypolyethylene glycol mono(meth)acrylate; Polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate; ) acrylate, polyalkylene such as polybutylene glycol mono(meth)acrylate, polyethylene glycol-polypropylene glycol mono(meth)acrylate, polyethylene glycol-polybutylene glycol mono(meth)acrylate, polypropylene glycol-polybutylene glycol mono(meth)acrylate, etc. Examples include glycol mono(meth)acrylate; mono(2-acryloyloxyethyl) succinate; and polylactone mono(meth)acrylate such as ω-carboxy-polycaprolactone mono(meth)acrylate. These monomers (A) may be used alone or in combination of two or more.
In addition, in this invention, the notation of (meth)acrylate means acrylate or methacrylate.

When the polymerizable component contains monomer (A), the weight proportion of monomer (A) in the polymerizable component is not particularly limited, but is preferably 3 to 100% by weight, and furthermore, (1 ) 3-90% by weight, (2) 5-90% by weight, (3) 10-90% by weight, (4) 15-80% by weight, (5) 15-70% by weight, (6) 20-70% by weight %, (7) 20 to 50% by weight, and (8) 25 to 50% by weight (the larger the value in parentheses is, the more preferable it is). When the weight ratio is 3% by weight or more, there is a tendency for both expansion performance and biodegradability to be achieved.

The polymerizable component may contain, as a monomer component, a monomer component other than monomer (A) (hereinafter sometimes simply referred to as other monomer component).
Other monomer components include, for example, nitrile monomers such as acrylonitrile, methacrylonitrile, fumaronitrile, and maleonitrile; halogenated vinyl monomers such as vinyl chloride; and halogenated vinylidene monomers such as vinylidene chloride. vinyl ester monomers other than monomer (A) such as vinyl acetate, vinyl propionate, vinyl butyrate; unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, cinnamic acid, etc. unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, citraconic acid, chloromaleic acid, anhydrides of unsaturated dicarboxylic acids, monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, Carboxyl group-containing monomers other than monomer (A) such as unsaturated dicarboxylic acid monoesters such as monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate; methyl (meth)acrylate, ethyl (meth)acrylate 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 other than monomer (A) such as benzyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate; ) Acrylamide monomers; maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide; styrenic monomers such as styrene and α-methylstyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, and isobutylene Vinyl ether monomers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Vinyl ketone monomers such as vinyl methyl ketone; N-vinyl monomers such as N-vinyl carbazole and N-vinyl pyrrolidone Monomer; examples include vinylnaphthalene salt. In the carboxyl group-containing monomer, some or all of the carboxyl groups may be neutralized during or after polymerization. These other monomer components may be used alone or in combination of two or more.
In the present invention, acrylic acid and methacrylic acid may be collectively referred to as (meth)acrylic acid, and (meth)acrylic means acrylic or methacrylic.

The polymerizable component is at least one selected from nitrile monomers, carboxyl group-containing monomers other than monomer (A), and (meth)acrylic acid ester monomers other than monomer (A). It is preferable that the monomer (B) as a seed is further included because the expansion performance is improved.
When the polymerizable component further contains a monomer (B), the weight proportion of the monomer (B) in the polymerizable component is not particularly limited, but is preferably from 5 to 97% by weight, and ( 1) 5-95% by weight, (2) 5-90% by weight, (3) 10-90% by weight, (4) 10-85% by weight, (5) 10-80% by weight, (6) 15-80 Weight%, (7) 20 to 80% by weight, and (8) 25 to 80% by weight are preferable in this order (the larger the value in parentheses is, the more preferable it is).

It is preferable that the nitrile monomer contains acrylonitrile and/or methacrylonitrile, since this improves the rigidity of the thermoplastic resin forming the outer shell. When the nitrile monomer contains acrylonitrile, the weight proportion of acrylonitrile in the nitrile monomer is not particularly limited, but is preferably 5 to 100% by weight, more preferably 10 to 90% by weight, and even more preferably 10 to 80% by weight, particularly preferably 25 to 80% by weight.
When the nitrile monomer contains methacrylonitrile, the weight proportion of methacrylonitrile in the nitrile monomer is not particularly limited, but is preferably 5 to 100% by weight, more preferably 10 to 90% by weight. , more preferably 10 to 80% by weight, particularly preferably 25 to 80% by weight.

The polymerizable component may further contain a halogenated vinylidene monomer as a monomer component. It is preferable to include a vinylidene halide monomer because the gas barrier properties of the thermoplastic resin forming the outer shell are improved. When the polymerizable component contains a halogenated vinylidene monomer, the weight proportion of the halogenated vinylidene monomer in the polymerizable component is not particularly limited, but is preferably 5 to 55% by weight.

The polymerizable component may contain a crosslinking agent as described above. In the thermally expandable microspheres obtained by polymerization using a crosslinking agent, a decrease in the retention rate (inclusion retention rate) of the encapsulated foaming agent during thermal expansion is suppressed, and it is possible to effectively thermally expand the microspheres. can.
The crosslinking agent is not particularly limited, but includes, for example, aromatic divinyl compounds such as divinylbenzene; allyl methacrylate, triacryl formal, triallyl isocyanate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and Ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polytetramethylene glycol diacrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1, 9-nonanediol di(meth)acrylate, PEG #200 di(meth)acrylate, PEG #400 di(meth)acrylate, PEG #600 di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerysrtol tetraacrylate, dipentaerysrtol hexaacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, tricyclodecane dimethanol di(meth)acrylate, etc. Examples include polyfunctional (meth)acrylate compounds. These crosslinking agents may be used alone or in combination of two or more.

There may be no crosslinking agent, but there is no particular limitation on its amount, preferably 0 to 5.0 parts by weight, more preferably 0.01 to 3.0 parts by weight, based on 100 parts by weight of the monomer component. parts, more preferably 0.02 to 2.0 parts by weight, particularly preferably 0.05 to 1.5 parts by weight. When the content of the crosslinking agent is 5.0 parts by weight or less, the expansion performance of the thermally expandable microspheres tends to improve.

The foaming agent is a component that vaporizes when heated, and is included in the outer shell of the thermally expandable microspheres, making the thermally expandable microspheres thermally expandable as a whole. It begins to exhibit the property of expanding when heated.

Foaming agents are not particularly limited, but include, for example, linear hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, nonane, decane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nanodecane; isobutane; , isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, isododecane, 3-methylundecane, isotridecane, 4-methyldodecane, isotetradecane, isopentadecane, isohexadecane, 2,2,4,4,6,8,8- Branched hydrocarbons such as heptamethylnonane, isoheptadecane, isooctadecane, isonanodecane, 2,6,10,14-tetramethylpentadecane; cyclododecane, cyclotridecane, hexylcyclohexane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, Hydrocarbons such as nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, octadecylcyclohexane; Petroleum ether; Their halides; Fluorine-containing compounds such as hydrofluoroether; Tetraalkylsilane; Thermal decomposition by heating Examples include compounds that generate gas. The blowing agent may be linear, branched, or alicyclic, and is preferably aliphatic. Moreover, these blowing agents may be used alone or in combination of two or more.

In the thermally expandable microspheres of the present invention, the degree of biodegradation (De1) (hereinafter sometimes simply referred to as De1) for 5 days measured in accordance with JIS K6950:2000 is more than 0%, preferably It is more than 0% and less than 70%. If the De1 is 0%, it does not have biodegradability. On the other hand, when the De1 is 70% or less, it tends to have good expansion performance. The De1 is preferably (1) 3 to 70%, (2) 5 to 60%, (3) 7 to 60%, (4) 10 to 60%, and (5) 10 to 50% (in parentheses). The larger the value, the better).
Note that the biodegradation degree (De1) of the thermally expandable microspheres for 5 days measured in accordance with JIS K6950:2000 is based on the method described in the Examples of the present invention.

The heat-expandable microspheres of the present invention are not particularly limited, but in terms of achieving the effects of the present invention, the heat-expandable microspheres are immersed in acetonitrile for 24 hours and then measured in accordance with JIS K6950:2000. The daily biodegradability (De2) (hereinafter sometimes simply referred to as De2) is preferably more than 0%, more preferably more than 0% and 70% or less. The De2 is a value measured for the biodegradability of the thermoplastic resin, which is a component other than the blowing agent that constitutes the thermally expandable microspheres and is a component that mainly forms the outer shell. From this, when the De2 is more than 0%, biodegradability tends to improve. Further, when the upper limit of De2 is 70%, the denseness of the outer shell and the stretchability during softening become sufficient, and the expansion performance tends to improve. The De2 is (1) 5-70%, (2) 5-65%, (3) 5-60%, (4) 7-60%, (5) 10-60%, (7) 10-55 %, (8) 15-55%, and (9) 15-50% (the larger the value in parentheses is, the more preferable it is).
In addition, the biodegradation degree (De2) of the thermally expandable microspheres for 5 days after being immersed for 24 hours, measured in accordance with JIS K6950:2000, is based on the method described in the examples of the present invention. .
Moreover, in the thermally expandable microspheres of the present invention, although there are no particular limitations, it is preferable that De2≧De1 be satisfied in order to achieve the effects of the present invention.

The average particle diameter of the thermally expandable microspheres of the present invention is not particularly limited, but is preferably 0.5 to 200 μm, and furthermore, (1) 1 to 150 μm, (2) 2 to 100 μm, (3) 3 ~100 μm, (4) 5 to 100 μm, (5) 5 to 75 μm, and (6) 5 to 50 μm (the larger the value in parentheses is, the more preferable it is). When the average particle size is 0.5 μm or more, the expansion performance of the thermally expandable microspheres tends to improve, and when the average particle size is 200 μm or less, the expansion stability of the thermally expandable microspheres tends to improve. There is. Note that the average particle diameter of the thermally expandable microspheres is determined by the method described in Examples of the present invention.

The coefficient of variation CV of the particle size distribution of the thermally expandable microspheres is not particularly limited, but is preferably 50% or less, more preferably 45% or less, particularly preferably 40% or less. The coefficient of variation CV is calculated using formulas (1) and (2) shown below.

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

(In the formula, s is the standard deviation of the particle diameter, <x> is the average particle diameter, xi is the i-th particle diameter, and n is the number of particles.)

The encapsulation ratio of the blowing agent is defined as the percentage of the weight of the blowing agent encapsulated in the heat-expandable microspheres to the weight of the heat-expandable microspheres. The inclusion rate of the blowing agent is not particularly limited, but is preferably 1 to 50% by weight, more preferably 2 to 45% by weight, even more preferably 5 to 40% by weight, particularly preferably 10 to 35% by weight.
The encapsulation rate of the foaming agent in the thermally expandable microspheres was determined by the method described in the Examples of the present invention.

The expansion start temperature (T _s ) of the thermally expandable microspheres is not particularly limited, but is preferably 80 to 300°C, more preferably 90 to 280°C, even more preferably 100 to 250°C, particularly preferably 110 to 250°C. °C, most preferably 120-250 °C. If the expansion start temperature of the thermally expandable microspheres is less than 80° C., the thermally expandable microspheres may not have sufficient heat resistance.
The maximum expansion temperature (T _max ) of the thermally expandable microspheres is not particularly limited, but is preferably 100 to 350°C, more preferably 110 to 300°C, even more preferably 120 to 280°C, particularly preferably 130 to 280°C. °C, most preferably 140-280 °C. Further, the upper limit of the maximum expansion temperature is preferably 350°C. If the maximum expansion temperature of the thermally expandable microspheres is less than 100°C, sufficient heat resistance may not be obtained, and if it exceeds 350°C, a sufficient expansion ratio may not be obtained.
Note that the expansion start temperature (T _s ) and maximum expansion temperature (T _max ) of the thermally expandable microspheres are determined by the method described in Examples of the present invention.

The maximum volumetric expansion ratio of the thermally expandable microspheres is not particularly limited, but is preferably 3 to 200 times, more preferably 5 to 200 times, even more preferably 10 to 200 times, particularly preferably 15 to 200 times, More preferably, it is 20 to 200 times.

The heat-expandable microspheres of the present invention can be used in paste compositions such as polyvinyl chloride pastes, and liquid compositions such as EVA emulsions, acrylic emulsions, and solvent-based binders. It can also be used for molding processes such as injection molding, extrusion molding, press molding, kneading molding, calendar molding, blow molding, compression molding, vacuum molding, and thermoforming.

[Method for manufacturing thermally expandable microspheres]
The manufacturing method for the thermally expandable microspheres of the present invention includes a step of dispersing an oily mixture containing a polymerizable component, a blowing agent, and a polymerization initiator in an aqueous dispersion medium, and polymerizing the polymerizable component ( (Hereinafter, it may be simply referred to as a polymerization step).

The polymerization initiator is not particularly limited, but commonly used peroxides, azo compounds, and the like can be mentioned.
Examples of peroxides include peroxydicarbonates such as diisopropylperoxydicarbonate, di-sec-butylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, and dibenzylperoxydicarbonate; dilauroylperoxydicarbonate; oxide, diacyl peroxide such as dibenzoyl peroxide; ketone peroxide such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxyketal such as 2,2-bis(t-butylperoxy)butane; cumene hydroperoxide, t - Hydroperoxides such as butyl hydroperoxide; dialkyl peroxides such as dicumyl peroxide and di-t-butyl peroxide; peroxy esters such as t-hexyl peroxypivalate and t-butyl peroxyisobutyrate can be mentioned.

Examples of azo compounds 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.

The amount of the polymerization initiator is not particularly limited, but is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, and most preferably 0.2 parts by weight based on 100 parts by weight of the polymerizable component. ~5 parts by weight. If the weight ratio is less than 0.05% by weight, unpolymerized polymerizable components may remain, making it impossible to stably produce desired thermally expandable microspheres. When the weight ratio exceeds 10% by weight, heat resistance may decrease.

In the polymerization process, the aqueous dispersion medium is a medium for dispersing an oily mixture that essentially includes a polymerizable component and a blowing agent, and has water such as ion-exchanged water as a main component. The aqueous dispersion medium may further contain an alcohol such as methanol, ethanol, and propanol, and a hydrophilic organic solvent such as acetone. Hydrophilicity in the present invention means a state in which it can be freely miscible with water. There is no particular limitation on the amount of the aqueous dispersion medium used, but it is preferable to use 100 to 1000 parts by weight of the aqueous dispersion medium per 100 parts by weight of the polymerizable component.

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.
The content of the electrolyte is not particularly limited, but it is preferably 0.1 to 50 parts by weight per 100 parts by weight of the aqueous dispersion medium.

The aqueous dispersion medium is a water-soluble 1,1-substituted compound 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 heteroatom are bonded to the same carbon atom. selected from the group consisting of potassium dichromate, alkali metal nitrites, metal (III) halides, boric acid, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble vitamin Bs, and water-soluble phosphonic acids (salts). It may contain at least one water-soluble compound. In addition, water-soluble in the present invention means a state in which 1 g or more is dissolved per 100 g 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 parts by weight, more preferably 0.0003 to 1.0 parts by weight, based on 100 parts by weight of the polymerizable component. 0.1 part by weight, particularly preferably 0.001 to 0.05 part 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. Furthermore, if the amount of the water-soluble compound is too large, the polymerization rate may decrease or the remaining amount of the polymerizable component as a raw material may increase.

The aqueous dispersion medium may contain a dispersion stabilizer and a dispersion stabilization aid in addition to the electrolyte and the water-soluble compound.
Examples of the dispersion stabilizer include tribasic calcium phosphate, magnesium pyrophosphate obtained by metathesis production method, calcium pyrophosphate, colloidal silica, alumina sol, magnesium hydroxide, and the like. These dispersion stabilizers may be used alone or in combination of two or more.
The amount of the dispersion stabilizer is preferably 0.05 to 30 parts by weight, more preferably 0.2 to 20 parts by weight, based on 100 parts by weight of the polymerizable component.

There are no particular limitations on the dispersion stabilizing aid, but examples include polymer-type dispersion stabilizing aids, cationic surfactants, anionic surfactants, amphoteric surfactants, nonionic surfactants, and other surfactants. Examples include activators and the like. These dispersion stabilizing aids may be used alone or in combination of two or more.

The aqueous dispersion medium is prepared, for example, by blending water (ion-exchanged water) with a water-soluble compound and, if necessary, a dispersion stabilizer and/or a dispersion stabilization aid. The pH of the aqueous dispersion medium during polymerization is appropriately determined depending on the type of water-soluble compound, dispersion stabilizer, and dispersion stabilization aid.

In the method for producing the heat-expandable microspheres of the present invention, polymerization may be carried out in the presence of sodium hydroxide and/or zinc chloride.
In the method for producing the thermally expandable microspheres of the present invention, an oily mixture is suspended and dispersed in an aqueous dispersion medium so that spherical oil droplets with a predetermined particle size are prepared.
Furthermore, in the polymerization step, a chain transfer agent, an organic pigment, an inorganic pigment or inorganic particles whose surface has been treated to be hydrophobic, etc. may be further used.

In the polymerization step, the oily mixture is suspended and dispersed in an aqueous dispersion medium so that spherical oil droplets with a predetermined particle size are prepared.
Examples of methods for suspending and dispersing the oily mixture include stirring with a homo mixer (for example, manufactured by Primix Co., Ltd.), or using a static dispersion device such as a static mixer (for example, manufactured by Noritake Co., Ltd.). General dispersion methods such as membrane emulsification method, ultrasonic dispersion method, etc. can be mentioned.
Next, suspension polymerization is initiated by heating an aqueous suspension in which the oily mixture is dispersed as spherical oil droplets in an aqueous dispersion medium. During the polymerization reaction, it is preferable to stir the aqueous suspension, and the stirring may be performed slowly enough to prevent, for example, floating of monomer components and sedimentation of thermally expandable microspheres after polymerization.

The polymerization temperature can be freely set depending on the type of polymerization initiator, but is preferably controlled within the range of 30 to 100°C, more preferably 40 to 90°C. The time for maintaining the reaction temperature is preferably about 0.1 to 20 hours. The initial polymerization pressure is not particularly limited, but it is 0 to 5.0 MPa in gauge pressure, more preferably 0.1 to 3.0 MPa.

The obtained slurry is filtered using a centrifuge, pressure press, vacuum dehydrator, etc. to obtain a wet powder with a moisture content of 10 to 50% by weight, preferably 15 to 45% by weight, and more preferably 20 to 40% by weight. Obtainable. Further, the obtained wet powder is dried using a tray dryer, an indirect heating dryer, a fluidized fluid dryer, a vacuum dryer, a vibration dryer, a flash dryer, or the like to obtain a dry powder. The moisture content of the obtained dry powder is preferably 8% by weight or less, more preferably 5% by weight or less.
Furthermore, for the purpose of reducing the content of ionic substances, the obtained wet powder or dry powder may be washed with water and/or redispersed, then filtered again, and dried. Alternatively, the slurry may be dried using a spray dryer, a fluidized fluid dryer, etc. to obtain a dry powder. Wet powder and dry powder can be selected as appropriate depending on the intended use.

[Hollow particles]
The hollow particles of the present invention are particles obtained by heating and expanding the thermally expandable microspheres described above, and are biodegradable and lightweight. Moreover, when it is included in a composition or a molded article, the material properties are excellent.

The hollow particles of the present invention are obtained by heating and expanding the thermally expandable microspheres described above, preferably at 80 to 450°C. The heating expansion method is not particularly limited and may be a dry heating expansion method, a wet heating expansion method, or the like. Examples of the dry heating expansion method include the method described in JP-A-2006-213930, particularly the internal injection method. Further, as another dry heating expansion method, there is a method described in JP-A No. 2006-96963. Examples of the wet heating expansion method include the method described in JP-A-62-201231.

The true specific gravity of the hollow particles of the present invention is not particularly limited, but is preferably 0.001 to 0.60. When the true specific gravity is 0.001 or more, the film thickness of the outer shell portion becomes sufficient, and there is a tendency that sagging can be suppressed. On the other hand, when the true specific gravity is 0.60 or less, the effect of lowering the specific gravity can be sufficiently obtained, and when preparing a composition using hollow particles, the physical properties of the composition or molded article can be sufficiently maintained. There is a tendency to do so. The true specific gravity is more preferably 0.003 to 0.50, still more preferably 0.005 to 0.40, particularly preferably 0.005 to 0.30, and most preferably 0.01 to 0.20. . Note that the true specific gravity of the hollow particles is determined by the method measured in Examples.

[Hollow particles with fine particles attached]
The fine particle-attached hollow particles of the present invention include the above-described hollow particles and fine particles attached to the outer surface of the outer shell portion of the hollow particles.For example, as shown in FIG. It is formed of fine particles (4 and 5) attached to the outer surface of the outer shell (2).
The adhesion mentioned here may simply be a state where the fine particles 4 and 5 are adsorbed to the outer surface of the outer shell 2 of the hollow particle (the state of the fine particle 4 in FIG. 2), and the outer shell near the outer surface may be This means that the constituting thermoplastic resin may be melted by heating, and the particulate filler may sink into the outer surface of the outer shell of the hollow particle and be in a fixed state (the state of particulate 5 in FIG. 2). The particle shape of the fine particles may be amorphous or spherical.
By adhering the fine particles to the hollow particles, scattering of the hollow particles can be suppressed and handling can be improved, and dispersibility in base material components such as binders and resins can also be improved.

Various types of particles can be used as the fine particles, and they may be made of either inorganic or organic materials. Examples of the shape of the fine particles include spherical, needle-like, and plate-like shapes.
The inorganic substances constituting the fine particles are not particularly limited, but include, for example, wollastenite, sericite, kaolin, mica, clay, talc, bentonite, alumina silicate, pyrophyllite, montmorillonite, calcium silicate, calcium carbonate, magnesium carbonate, Dolomite, calcium sulfate, barium sulfate, glass flakes, boron nitride, silicon carbide, silica, alumina, mica, titanium dioxide, zinc oxide, magnesium oxide, zinc oxide, hydrosultite, carbon black, molybdenum disulfide, tungsten disulfide, Examples include ceramic beads, glass beads, crystal beads, and glass microballoons.

The organic substances constituting the fine particles are not particularly limited, but include, for example, sodium carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, ethylcellulose, nitrocellulose, hydroxypropylcellulose, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, and carboxyvinyl. Polymer, polyvinyl methyl ether, magnesium stearate, calcium stearate, zinc stearate, polyethylene wax, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, hydrogenated castor oil, (meth)acrylic resin, polyamide resin, silicone resin , urethane resin, polyethylene resin, polypropylene resin, fluororesin, etc.
The inorganic and organic substances constituting the fine particles may be treated with a surface treatment agent such as a silane coupling agent, paraffin wax, fatty acid, resin acid, urethane compound, or fatty acid ester, or may be untreated.

The average particle diameter of the fine particles is not particularly limited, but is preferably 0.001 to 30 μm, more preferably 0.005 to 25 μm, particularly preferably 0.01 to 20 μm. Note that the average particle diameter is a value of a volume-based cumulative 50% particle diameter measured by a laser diffraction method.
Although the ratio of the average particle diameter of fine particles to the average particle diameter of hollow particles (average particle diameter of fine particles/average particle diameter of hollow particles) is not particularly limited, it is preferable in terms of adhesion of the fine particles to the surface of the hollow particles. is 1 or less, more preferably 0.1 or less, still more preferably 0.05 or less.

There is no particular limitation on the weight ratio of the fine particles to the entire hollow particles to which the fine particles are attached, but it is preferably 5 to 95% by weight, more preferably 10 to 90% by weight, even more preferably 20 to 85% by weight, and particularly preferably 30% by weight. ~80% by weight, particularly preferably 40-80% by weight. If the weight ratio exceeds 95% by weight, the amount of the hollow particles to be added becomes large when preparing a composition using the hollow particles to which the fine particles are attached, which may be uneconomical.

The true specific gravity of the hollow particles to which the fine particles are attached is not particularly limited, but is preferably 0.01 to 0.60, more preferably 0.03 to 0.40, even more preferably 0.05 to 0.30, and particularly preferably is 0.07 to 0.20. When the true specific gravity is 0.01 or more, the film thickness of the outer shell portion becomes sufficient, and there is a tendency that sagging can be suppressed. On the other hand, when the true specific gravity is 0.60 or less, the effect of lowering the specific gravity can be sufficiently obtained, and the physical properties of the composition or molded product can be sufficiently maintained when preparing a composition using the hollow particles with fine particles attached. There is a tendency to be able to.

The hollow particles to which fine particles are attached according to the present invention can be produced, for example, by heating and expanding thermally expandable microspheres to which fine particles are attached. The method for producing hollow particles with fine particles attached includes a step of mixing thermally expandable microspheres and fine particles (mixing step), heating the mixture obtained in the mixing step to a temperature above the softening point, and A manufacturing method including a step of expanding expandable microspheres and adhering microparticles to the outer surface of the resulting hollow particles (attachment step) is preferred.

The mixing step is a step of mixing the aforementioned thermally expandable microspheres and the aforementioned fine particles.
The weight ratio of the microparticles to the total of the thermally expandable microspheres and microparticles in the mixing step is not particularly limited, but is preferably 5 to 95% by weight, more preferably 10 to 90% by weight, and even more preferably 20 to 85% by weight. It is particularly preferably 30 to 80% by weight. When the weight ratio is 95% by weight or less, the obtained hollow particles to which fine particles are attached are lightweight, and a sufficient effect of lowering the specific gravity tends to be obtained.

In the mixing step, the device used to mix the thermally expandable microspheres and the fine particles is not particularly limited, and any device equipped with an extremely simple mechanism such as a container and a stirring blade can be used. Further, a powder mixer capable of general shaking or stirring may be used.
Examples of the powder mixer include powder mixers that can perform rocking agitation or agitation, such as a ribbon mixer and a vertical screw mixer. In addition, we also offer Super Mixer (manufactured by Kawata Co., Ltd.) and High Speed Mixer (manufactured by Fukae Co., Ltd.), which are more efficient and multifunctional powder mixers that combine stirring devices, New Gram Machine (manufactured by Seishin Enterprise Co., Ltd.), and SV. A mixer (manufactured by Kobelco Environmental Solutions Co., Ltd.) or the like may be used.

The adhesion step is a step of heating the mixture containing the thermally expandable microspheres and fine particles obtained in the above mixing step to a temperature above the softening point of the thermoplastic resin that constitutes the outer shell of the thermally expandable microspheres. be. In the attachment step, the thermally expandable microspheres are expanded and fine particles are attached to the outer surface of the outer shell of the resulting hollow particles.
Heating may be performed using a general contact heat transfer type or direct heating type mixing dryer. There are no particular limitations on the functions of the mixing type drying device, but it is preferable to have the ability to adjust the temperature, disperse and mix raw materials, and optionally have a pressure reducing device or cooling device to speed up drying. The device used for heating is not particularly limited, and examples thereof include Loedige mixer (manufactured by Matsubo Co., Ltd.), Solid Air (manufactured by Hosokawa Micron Co., Ltd.), and the like.
The temperature conditions for heating will depend on the type of thermally expandable microspheres, but should be around the maximum expansion temperature of the thermally expandable microspheres, preferably 70 to 250°C, more preferably 80 to 230°C, and Preferably it is 90 to 220°C.

[Composition and molded object]
The composition of the present invention contains at least one selected from the above-described thermally expandable microspheres, hollow particles, and hollow particles with fine particles attached thereto, and a base material component.
Examples of base material components include rubbers such as natural rubber, butyl rubber, silicone rubber, and ethylene-propylene-diene rubber (EPDM); thermosetting resins such as unsaturated polyester, epoxy resin, and phenolic resin; polyethylene wax, paraffin wax Waxes such as ethylene-vinyl acetate copolymer (EVA), ionomer, polyethylene, polypropylene, polyvinyl chloride (PVC), acrylic resin, thermoplastic polyurethane, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene -Styrene copolymer (ABS resin), polystyrene (PS), polyamide resin (nylon 6, nylon 66, etc.), polycarbonate, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyacetal (POM), polyphenylene sulfide (PPS) ); Thermoplastic elastomers such as olefin elastomers and styrene elastomers; polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymers, vinylidene fluoride-hexafluoro Fluorine-containing resins such as propylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, hexafluoropropylene-tetrafluoroethylene copolymer, ethylene-tetrafluoroethylene; polylactic acid (PLA), cellulose acetate, polybutylene saccharide Bioplastics such as PBS, polyhydroxyalkanoate (PHA), starch resin; sealing materials such as silicone, modified silicone, polysulfide, modified polysulfide, urethane, acrylic, polyisobutylene, butyl rubber, etc. ;Liquid components such as urethane-based, ethylene-vinyl acetate copolymer-based, vinyl chloride-based, and acrylic emulsions and plastisols;Inorganic materials such as cement, mortar, and cordierite;Cellulose, kenaf, bran, aramid fibers, and phenolic fibers , polyester fibers, acrylic fibers, polyolefin fibers such as polyethylene and polypropylene, polyvinyl alcohol fibers, and organic fibers such as rayon. These base material components may be diluted, dissolved, or dispersed in water or an organic solvent. These base material components may be used alone or in combination of two or more.

The composition of the present invention can be prepared by mixing at least one selected from thermally expandable microspheres, hollow particles, and hollow particles to which fine particles are attached, and a base material component. Further, a composition obtained by mixing at least one selected from thermally expandable microspheres, hollow particles, and hollow particles with fine particles attached thereto and a base material component may be further mixed with another base material component to form a base material. It can also be an inventive composition.
In addition to at least one selected from thermally expandable microspheres, hollow particles, and hollow particles to which microparticles are attached, and the base material component, the composition of the present invention may contain other components depending on the intended use. Other components include, for example, plasticizers, fillers, colorants, high-boiling organic solvents, adhesives, and the like.

In the composition of the present invention, the total content of thermally expandable microspheres, hollow particles, and hollow particles with fine particles attached is not particularly limited, but is preferably from 0.05 to 100 parts by weight based on 100 parts by weight of the base material component. It is 750 parts by weight. When the total content is 0.05 parts by weight or more, a sufficiently lightweight molded article tends to be obtained. On the other hand, when the total content is 750 parts by weight or less, the uniform dispersibility of at least one selected from thermally expandable microspheres, hollow particles, and hollow particles with fine particles attached tends to be further improved. The total content is more preferably 0.1 to 700 parts by weight, still more preferably 0.2 to 650 parts by weight, particularly preferably 0.5 to 600 parts by weight, and most preferably 1 to 500 parts by weight. .

The method for preparing the composition of the present invention is not particularly limited, and any conventionally known method may be employed. The method includes, for example, a homomixer, a static mixer, a Henschel mixer, a tumbler mixer, a planetary mixer, a kneader, a roll, a mixing roll, a mixer, a single-screw kneader, a twin-screw kneader, a multi-screw kneader, and other mixers. An example of this method is to mechanically mix the mixture uniformly using a .
Examples of the composition of the present invention include a rubber composition, a molding composition, a coating composition, a clay composition, an adhesive composition, and a powder composition.

The molded article of the present invention is obtained by molding the composition described above.
Examples of the molded article of the present invention include molded articles and coating films.
The molded article of the present invention has improved physical properties such as lightness, porosity, sound absorption, heat insulation, low thermal conductivity, low dielectric constant, design, shock absorption, and strength, and also has an excellent appearance. You can also get the effect.

Examples of the thermally expandable microspheres of the present invention will be specifically described below. Note that 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.
Furthermore, the physical properties of the thermally expandable microspheres mentioned in the following Examples and Comparative Examples were measured in the manner shown below, and the performance was further evaluated. Hereinafter, thermally expandable microspheres may be referred to as "microspheres" for simplicity.

[Measurement of average particle diameter (D50) and particle size distribution of thermally expandable microspheres]
As a measuring device, a Microtrack particle size distribution meter (Model 9320-HRA) manufactured by Nikkiso Co., Ltd. was used, and the D50 value determined by volume-based measurement was taken as the average particle diameter.

[Measurement of the expansion start temperature (T _s ) and maximum expansion temperature (T _max ) of thermally expandable microspheres]
A DMA (DMA Q800 model manufactured by TA instruments) was used as a measuring device. 0.5 mg of thermally expandable microspheres was placed in an aluminum cup with a diameter of 5.6 mm and a depth of 4.8 mm, and an aluminum lid (diameter 5.6 mm, thickness 0.1 mm) was placed on top of the thermally expandable microsphere layer. A sample was prepared. The height of the sample was measured while applying a force of 0.01 N to the sample from above using a presser. The sample was heated from 20° C. to 350° C. at a temperature increase rate of 10° C./min while applying a force of 0.01 N using a presser, and the amount of displacement of the presser in the vertical direction was measured. The displacement start temperature in the positive direction was defined as the expansion start temperature (T _s ), and the temperature at which the maximum displacement (H _max ) occurred was defined as the maximum expansion temperature (T _max ).

[Measurement of water content (C _w1 ) of thermally expandable microspheres]
The measurement was performed using a Karl Fischer moisture meter (model MKA-510N, manufactured by Kyoto Electronics Industry Co., Ltd.) as a measuring device. The moisture content (% by weight) of the thermally expandable microspheres was defined as _Cw1 .

[Measurement of encapsulation rate (C ₁ ) of foaming agent in thermally expandable microspheres]
1.0 g of thermally expandable microspheres was placed in a stainless steel evaporation dish with a diameter of 80 mm and a depth of 15 mm, and its weight (W ₁ (g)) was measured. After adding 30 ml of acetonitrile and uniformly dispersing the mixture and allowing it to stand at room temperature for 24 hours, the weight (W ₂ (g)) after drying under reduced pressure at 130° C. for 2 hours was measured.
The encapsulation rate (C ₁ ) of the foaming agent in the thermally expandable microspheres was calculated using the following formula.
C ₁ (weight %) = 100×{100×(W ₁ −W ₂ )/1.0−C _w1 }/(100−C _w1 )
(In the formula, the water content C _w1 of the thermally expandable microspheres was the value measured by the above method.)

[Measurement of true specific gravity]
The true specific gravity of thermally expandable microspheres, hollow particles, or hollow particles with fine particles attached (hereinafter sometimes simply referred to as particle samples) was measured by the following measurement method.
The true specific gravity was measured by an immersion method (Archimedes method) using isopropyl alcohol in an atmosphere of an environmental temperature of 25° C. and a relative humidity of 50%. Specifically, a volumetric flask with a capacity of 100 mL was emptied, and after drying, the weight of the volumetric flask (WB1) was measured. After accurately filling the weighed volumetric flask with isopropyl alcohol up to the meniscus, the weight (WB2) of the volumetric flask filled with 100 mL of isopropyl alcohol was weighed. Further, a volumetric flask with a capacity of 100 mL was emptied, and after drying, the weight of the volumetric flask (WS1) was measured. Approximately 50 mL of the particle sample was filled into the weighed volumetric flask, and the weight (WS2) of the volumetric flask filled with the particle sample was weighed. Then, the volumetric flask filled with the particle sample was filled with isopropyl alcohol up to the meniscus without any air bubbles, and then the weight (WS3) was measured. Then, the obtained WB1, WB2, WS1, WS2, and WS3 were introduced into the following formula to calculate the true specific gravity (d) of the particle sample.
d={(WS2-WS1)×(WB2-WB1)/100}/{(WB2-WB1)-(WS3-WS2)}

[Measurement of true specific gravity after expansion of thermally expandable microspheres]
A box with a flat bottom measuring 12 cm in length, 13 cm in width, and 9 cm in height was made from aluminum foil, and 1.0 g of thermally expandable microspheres were uniformly placed in the box, and the box was covered with aluminum foil. The box with the lid was placed in a gear type oven and heated for 1 minute at the maximum expansion temperature of the thermally expandable microspheres described above to obtain an expanded body. The true specific gravity of the hollow particles, which were the expanded bodies obtained, was measured by the method described above. It means that the smaller the true specific gravity of the expanding body, the better the expanding performance.

[Measurement of biodegradation level (De1)]
The degree of biodegradation (De1) of the thermally expandable microspheres was measured in accordance with JIS K6950:2000. Specifically, the following steps were performed.
First, in order to prepare an inorganic salt medium, the following solutions A to D were prepared.
(Solution A)
8.5 g of anhydrous potassium dihydrogen phosphate, 21.75 g of anhydrous dipotassium hydrogen phosphate, 33.4 g of disodium hydrogen phosphate dihydrate, and 0.5 g of ammonium chloride were dissolved in water to make a solution A with a total volume of 1000 mL. was prepared.
(Solution B)
22.5 g of magnesium sulfate heptahydrate was dissolved in water to prepare a solution B with a total volume of 1000 mL.
(Solution C)
36.4 g of calcium chloride dihydrate was dissolved in water to prepare a solution C with a total volume of 1000 mL.
(Solution D)
0.25 g of iron (III) chloride hexahydrate was dissolved in water to prepare a solution D with a total volume of 1000 mL. Regarding solution D, in order to prevent precipitation, a new solution was prepared immediately before use, or one drop of concentrated hydrochloric acid or one drop of 0.4 g/L aqueous solution of ethylenediaminetetraacetic acid was added.
Next, 10 mL of solution A and 1 mL each of solutions B to D were added to 500 mL of water, and water was further added to make the total volume 1000 mL. This was used as an inorganic salt medium.
200 mL of an inorganic salt medium was placed in a 300 mL culture bottle, and then 30 mg of thermally expandable microspheres and 45 mg of activated sludge for sewage treatment were added, and then 100 mL of an inorganic salt medium was added to prepare a measurement sample. The prepared measurement sample was allowed to stand at 25°C for 5 days, and the amount of oxygen consumed (BOD1) after the stand was measured.
Separately, 200 mL of inorganic salt medium was placed in a 300 mL culture bottle, 45 mg of activated sludge for sewage treatment was added, and then 100 mL of inorganic salt medium was added to prepare blank samples. The prepared blank was left to stand for 5 days under the same conditions as above, and the oxygen consumption (BOD0) was measured.
The degree of biodegradation (De1) was calculated from the following formula from the theoretical maximum amount of oxygen ThOD1 required to oxidize the thermally expandable microspheres, and the above-mentioned BOD1 and BOD0. Note that when De1 is 0%, it means that the thermally expandable microspheres do not exhibit biodegradability.
Biodegradation level (De1) (%) = 100 x (BOD1-BOD0)/ThOD1

[Measurement of biodegradation level (De2)]
The degree of biodegradation (De2) after the thermally expandable microspheres were immersed in acetonitrile for 24 hours was measured in accordance with JIS K6950:2000. Specifically, the following steps were performed.
First, 1.0 g of thermally expandable microspheres was placed in a stainless steel evaporation dish with a diameter of 80 mm and a depth of 15 mm, and 30 ml of acetonitrile was added to disperse it uniformly. After standing at room temperature for 24 hours, it was dried under reduced pressure at 130°C for 2 hours. A residue after the immersion treatment was obtained.
Next, the oxygen consumption BOD3 of the obtained residue was measured in the same manner as the method for measuring the degree of biodegradation (De1) explained above. Based on the BOD3, the oxygen consumption amount BOD0 measured above, and the theoretical maximum amount of oxygen ThOD2 required to oxidize the obtained residue, the raw material after immersing the thermally expandable microspheres in acetonitrile for 24 hours was determined. The degree of decomposition (De2) was calculated by changing BOD1 to BOD3 and ThOD1 to ThOD2 in the formula calculated by De1 above.

(Example 1)
Dissolve 130 parts of sodium chloride in 500 parts of ion-exchanged water, add 1.0 part of polyvinylpyrrolidone, 0.05 part of carboxymethylated polyimine/Na salt, and 65 parts of colloidal silica (effective concentration 20%), and adjust the pH. 3.0 to prepare an aqueous dispersion medium.
Separately, 5 parts of methoxypolyethylene glycol monomethacrylate (average number of constituent units of ethylene glycol: 4), 30 parts of acrylonitrile, 7 parts of methacrylonitrile, 49 parts of methacrylic acid, 8 parts of methacrylamide, 4 parts of styrene, ethylene glycol 2 parts of dimethacrylate, 2 parts of di-2-ethylhexyl peroxydicarbonate (purity 70%), and 40 parts of 2-methylbutane (isopentane) were mixed to form an oily mixture.
The aqueous dispersion medium and the oily mixture were mixed, and the resulting mixture was dispersed for 1 minute at a rotation speed of 10,000 rpm using a homomixer (manufactured by Primix Co., Ltd., TK Homomixer) to prepare an aqueous suspension.
The obtained aqueous suspension was transferred to a pressurized reactor with a capacity of 1.5 liters, and the reactor was purged with nitrogen.The initial reaction pressure was then set to 0.35 MPa, and a polymerization reaction was carried out at a polymerization temperature of 60°C for 20 hours while stirring at 80 rpm. . After polymerization, the product was filtered and dried to obtain thermally expandable microspheres. The physical properties of the obtained thermally expandable microspheres were measured and evaluated. The results are shown in Table 1.

(Examples 2 to 18, Comparative Examples 1 to 4)
In Examples 2 to 18 and Comparative Examples 1 to 4, thermally expandable microspheres were obtained in the same manner as in Example 1, except for the changes shown in Tables 1 to 3.
The physical properties of each of the obtained thermally expandable microspheres were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1 to 3.
In addition, in Tables 1 to 3, the following abbreviations are used. Further, for example, "n=(≈)3" indicates that the average structural unit is 3.
Perloyl OPP: di-2-ethylhexyl peroxydicarbonate (purity 70%)
Isobutane: 2-methylpropane Isopentane: 2-methylbutane

The thermally expandable microspheres of the present invention can be used, for example, as a lightweighting material for putty, paint, ink, sealant, mortar, paper clay, pottery, etc., and can be used together with base material components to perform injection molding, extrusion, etc. By performing molding such as molding, press molding, etc., it is possible to produce a molded body having excellent sound insulation, heat insulation, heat insulation, sound absorption, etc. properties.

1 Hollow particles with fine particles attached 2 Outer shell portion 3 Hollow portion 4 Fine particles (adsorbed state)
5 Fine particles (embedded, immobilized state)
6 Outer shell
7 Foaming agent (core)

Claims (6)

A thermally expandable microsphere comprising an outer shell containing a thermoplastic resin and a foaming agent that is encapsulated in the outer shell and vaporizes when heated,
The blowing agent is at least one selected from linear hydrocarbons, branched hydrocarbons, and alicyclic hydrocarbons,
The thermoplastic resin is a polymer of polymerizable components containing a monomer (A) and a monomer (B),
An alkoxypolyoxyalkylene mono(meth)acrylate in which the monomer (A) has an oxyalkylene structure having 2 to 30 structural units, and a polyalkylene glycol mono having an oxyalkylene structure having 2 to 30 structural units. At least one member selected from (meth)acrylate, polylactone mono(meth)acrylate having a hydroxycarboxylic acid structure having 2 to 30 structural units, and mono(2-acryloyloxyethyl) succinate,
The monomer (B) is at least one selected from carboxyl group-containing monomers and nitrile monomers other than monomer (A),
The weight proportion of the monomer (A) in the polymerizable component is 5 to 90% by weight,
The weight proportion of the monomer (B) in the polymerizable component is 5 to 95% by weight,
Thermally expandable microspheres have a biodegradability (De1) of 3% or more at 25°C for 5 days using activated sludge for sewage treatment, measured in accordance with JIS K6950:2000. Claim 1, wherein the biodegradability (De2) of activated sludge for sewage treatment after immersion in acetonitrile for 24 hours and measured in accordance with JIS K6950:2000 at 25°C for 5 days is 5% or more. The thermally expandable microspheres described. Hollow particles which are expanded bodies of the thermally expandable microspheres according to claim 1. Hollow particles with fine particles attached thereto, comprising the hollow particles according to claim 3 and fine particles adhered to the outer surface of the outer shell portion of the hollow particles. A composition comprising at least one selected from the thermally expandable microspheres according to claim 1 or 2, the hollow particles according to claim 3 , and the fine particle-attached hollow particles according to claim 4 , and a base material component. . A molded article obtained by molding the composition according to claim 5 .

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