Heat-expandable microspheres, their manufacturing method and uses

Abstract

To provide a heat-expandable microsphere and a method for producing the same that is excellent in heat resistance and has a high expansion characteristic, and to provide application.MEANS FOR SOLVING THE PROBLEM: Provided is a heat-expandable microsphere, which is a heat-expandable microsphere composed of an outer shell made of thermoplastic resin and a foaming agent contained therein and vaporized by heating, and in which the thermoplastic resin is a polymer of a polymerizable component containing a monomer (A), and the monomer (A) has a hydroxyl group, a lactone ring, and one polymerizable carbon-carbon double bond.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to heat-expandable microspheres, their production method and uses. [Background technology]

[0002] Heat-expandable microspheres, which have a thermoplastic resin shell and a foaming agent enclosed inside, are generally called heat-expandable microspheres (heat-expandable microcapsules). Heat-expandable microspheres are microspheres that have the characteristic of expanding when subjected to heat treatment. These heat-expandable microspheres are used in a wide range of applications, for example, when they are blended with a substrate. By heat treatment during molding, the heat-expandable microspheres expand simultaneously with molding, and can not only reduce the weight of the molded product but also impart design properties, cushioning properties, etc. to the molded product. To ensure the expansion function of heat-expandable microspheres, the thermoplastic resin used for the shell is usually required to have gas barrier properties. For example, heat-expandable microspheres that use a shell made of a vinylidene chloride copolymer, an acrylonitrile copolymer, an acrylic copolymer, or the like and mainly use a hydrocarbon such as isobutane or isopentane as a blowing agent have been disclosed (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 3,615,972 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it has been confirmed that the heat-expandable microspheres disclosed in Patent Document 1 exhibit good thermal expansion behavior but at relatively low temperatures, and therefore lack heat resistance during molding and are unable to expand effectively. Thus, there have been no heat-expandable microspheres having such excellent heat resistance and high expansion properties.

[0005] An object of the present invention is to provide heat-expandable microspheres having excellent heat resistance and high expansion properties, a production method thereof, and uses thereof. [Means for solving the problem]

[0006] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by heat-expandable microspheres which are composed of an outer shell made of a thermoplastic resin obtained by polymerizing a specific polymerizable component and a blowing agent encapsulated within the shell and vaporized by heating, thereby completing the present invention.

[0007] That is, the present invention relates to heat-expandable microspheres which are composed of an outer shell made of a thermoplastic resin and a blowing agent encapsulated therein and which vaporizes when heated, the thermoplastic resin being a polymer of a polymerizable component containing a monomer (A), and the monomer (A) having a hydroxyl group, a lactone ring, and one polymerizable carbon-carbon double bond.

[0008] In the heat-expandable microspheres of the present invention, it is preferable that at least one of the carbon atoms constituting the polymerizable carbon-carbon double bond is the same as the carbon atom constituting the lactone ring, excluding the carbon atom constituting the carbonyl group. In the heat-expandable microspheres of the present invention, the hydroxyl group and the lactone ring are preferably bonded to each other. In the heat-expandable microspheres of the present invention, the monomer (A) is preferably a compound represented by the following general formula (1):

[0009] [ka] (In the formula, R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

[0010] The method for producing heat-expandable microspheres of the present invention is a method for producing heat-expandable microspheres which are composed of an outer shell made of a thermoplastic resin and a blowing agent encapsulated in the outer shell and vaporized by heating, and comprises the steps of dispersing a polymerizable component and the blowing agent in an aqueous dispersion medium and polymerizing the polymerizable component, the polymerizable component comprising a monomer (A) having a hydroxyl group, a lactone ring, and one polymerizable carbon-carbon double bond.

[0011] The resin hollow particles of the present invention are expanded products of the above-mentioned heat-expandable microspheres. The microparticle-coated hollow resin particles of the present invention comprise the above-mentioned hollow resin particles and microparticles that are coated on the outer surface of the shell of the hollow resin particles.

[0012] The composition of the present invention contains at least one member selected from the group consisting of the heat-expandable microspheres, the hollow resin particles, and the microparticle-coated hollow resin particles, and a base component. The molded article of the present invention is obtained by molding the above composition. Effect of the Invention

[0013] The heat-expandable microspheres of the present invention have excellent heat resistance and high expansion performance. The resin hollow particles of the present invention are obtained using the above-mentioned heat-expandable microspheres as a raw material, and therefore have excellent heat resistance and a low specific gravity. The microparticle-coated hollow resin particles of the present invention are obtained using the above-mentioned heat-expandable microspheres as a raw material, and therefore have excellent heat resistance and a low specific gravity. The composition of the present invention contains at least one member selected from the group consisting of the heat-expandable microspheres, the hollow resin particles, and the fine particle-coated hollow resin particles, and therefore can give a lightweight molded article. The molded article of the present invention is lightweight. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing an example of heat-expandable microspheres. [Diagram 2] FIG. 2 is a schematic diagram showing an example of fine particle-adhered resin hollow particles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [Thermally expandable microspheres] As shown in Fig. 1, the heat-expandable microspheres of the present invention are composed of an outer shell 6 made of a thermoplastic resin and a foaming agent (core) 7 encapsulated therein that vaporizes when heated. These heat-expandable microspheres have a core-shell structure, and the microspheres as a whole exhibit thermal expandability (the property that the entire microsphere expands when heated). The thermoplastic resin is obtained by polymerizing a polymerizable component.

[0016] The polymerizable component is a component that becomes a thermoplastic resin that forms the outer shell of the heat-expandable microspheres through polymerization. The polymerizable component is a component that essentially contains a monomer component and may contain a crosslinking agent. The monomer component means a monomer having one polymerizable carbon-carbon double bond and is a component capable of addition polymerization. The crosslinking agent means a monomer having at least two polymerizable carbon-carbon double bonds and is a component that introduces a crosslinked structure into the thermoplastic resin.

[0017] The polymerizable component contains a monomer (A) having a hydroxyl group, a lactone ring, and one polymerizable carbon-carbon double bond. When the polymerizable component contains the monomer (A), the resulting polymer can have a lactone ring and a hydroxyl group. It is believed that the polymer has a lactone ring, and therefore the polymer has rigidity. Furthermore, it is believed that the polymer has a hydroxyl group, and therefore the resulting thermoplastic resin can have gas barrier properties. It is believed that the resulting heat-expandable microspheres have excellent heat resistance and high expansion properties.

[0018] The lactone ring in the monomer (A) is not particularly limited, but is preferably a 5- to 11-membered ring structure. When the lactone ring in the monomer (A) has a ring member number within the above range, the production stability of the heat-expandable microspheres tends to be improved. The upper limit of the number of ring members in the lactone ring is more preferably an 8-membered ring, further preferably a 7-membered ring, and particularly preferably a 6-membered ring.

[0019] The monomer (A) is not particularly limited, but it is preferable that at least one of the carbon atoms constituting the carbon-carbon double bond is the same as the carbon atom constituting the lactone ring excluding the carbon atom constituting the carbonyl group. When at least one of the carbon atoms constituting the carbon-carbon double bond is the same as the carbon atom constituting the lactone ring excluding the carbon atom constituting the carbonyl group, the lactone ring can be incorporated into the obtained polymer chain, the rigidity of the polymer is improved, the free volume of the polymer is reduced, the entanglement density of the molecular chain due to the intermolecular interaction of the polymer is increased, and the thermoplastic resin can have high viscoelasticity, so that it is considered that high thermal expansion properties can be obtained. When at least one of the carbon-carbon double bonds in the monomer (A) is the same as a carbon atom constituting a lactone ring excluding the carbon atom constituting the carbonyl group, a preferred embodiment is one in which one of the carbon atoms constituting the carbon-carbon double bond is the same as a carbon atom constituting a lactone ring excluding the carbon atom constituting the carbonyl group.

[0020] The monomer (A) is not particularly limited, but it is preferable that the hydroxyl group and lactone ring of the monomer (A) are bonded together. When the hydroxyl group and lactone ring are bonded together, the charge bias cohesive energy density of the resulting polymer increases, and the thermoplastic resin can have high gas barrier properties, which is believed to result in high thermal expansion properties. The number of hydroxyl groups contained in the monomer (A) is not particularly limited, but is preferably 1 to 3, more preferably 1 or 2, and particularly preferably 1.

[0021] The monomer (A) is not particularly limited, but is preferably a compound represented by the following general formula (1) since it can enhance the rigidity and gas barrier properties of the resulting polymer chain.

[0022] [ka]

[0023] In the formula, R1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R in general formula (1) 1 When is an alkyl group having 1 to 8 carbon atoms, the number of carbon atoms in the alkyl group is not particularly limited, but is more preferably 1 to 5, even more preferably 1 to 3, particularly preferably 1 to 2, and most preferably 1 (methyl group). R 1 As an embodiment of the alkyl group, a hydrogen atom is preferable since the entanglement density of the resulting polymer chains can be further increased.

[0024] R in general formula (1) 2 When is an alkyl group having 1 to 8 carbon atoms, the number of carbon atoms in the alkyl group is not particularly limited, but is more preferably 1 to 5, even more preferably 1 to 3, particularly preferably 1 to 2, and most preferably 1 (methyl group). R 2 As an embodiment of the alkyl group, a hydrogen atom is preferable since the entanglement density of the resulting polymer chains can be further increased.

[0025] Examples of the monomer (A) include swertiamarin, andrographolide, α-methylene-β-hydroxy-γ-butyrolactone, and the like. These monomers (A) may be used alone or in combination of two or more. The monomer (A) may be a compound derived from a living organism such as an animal or a plant.

[0026] The weight ratio of the monomer (A) in the polymerizable component is not particularly limited, but is preferably 5% by weight or more. If the weight ratio of the monomer (A) in the polymerizable component is less than 5% by weight, the effect of the present invention may not be obtained. The upper limit of the weight ratio of the monomer (A) in the polymerizable component is preferably 100% by weight, more preferably 90% by weight, even more preferably 75% by weight, particularly preferably 65% ​​by weight, and most preferably 50% by weight. On the other hand, the lower limit of the weight ratio of the monomer (A) is more preferably 10% by weight, even more preferably 15% by weight, particularly preferably 20% by weight, and most preferably 25% by weight.

[0027] The polymerizable component may contain, as a monomer component, a monomer component other than the monomer (A) (sometimes simply referred to as other monomer component). Examples of other monomer components include nitrile monomers such as acrylonitrile, methacrylonitrile, fumaronitrile, and maleonitrile; vinyl halide monomers such as vinyl chloride; vinylidene halide monomers such as vinylidene chloride; vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl butyrate; unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid; maleic acid, itaconic acid, fumaric acid, citraconic acid, Carboxyl group-containing monomers such as unsaturated dicarboxylic acids, anhydrides of unsaturated dicarboxylic acids, and unsaturated dicarboxylic acid monoesters, such as monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate; methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, (meth)acrylic acid ester monomers such as acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 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; ethylenically unsaturated monoolefin monomers such as ethylene, propylene, and isobutylene; vinyl ether monomers such as vinyl 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; and vinyl naphthalene salts. The carboxyl group-containing monomer may have some or all of its carboxyl groups neutralized during or after polymerization. In the present invention, acrylic acid and methacrylic acid may be collectively referred to as (meth)acrylic acid, and acrylate and methacrylate may be collectively referred to as (meth)acrylate.In addition, (meth)acrylate means acrylate or methacrylate, and (meth)acrylic means acrylic or methacrylic. These other monomer components may be used alone or in combination of two or more.

[0028] The polymerizable component may further contain a nitrile monomer as a monomer component, which is preferable because it improves the solvent resistance of the heat-expandable microspheres. When the polymerizable component contains a nitrile monomer, the weight ratio of the nitrile monomer in the polymerizable component is not particularly limited, but is preferably 5 to 95% by weight. When the weight ratio of the nitrile monomer is within the above range, the solvent resistance of the heat-expandable microspheres tends to be improved. The upper limit of the weight ratio of the nitrile monomer is more preferably 90% by weight, further preferably 85% by weight, particularly preferably 80% by weight, and most preferably 75% by weight. On the other hand, the lower limit of the weight ratio of the nitrile monomer is more preferably 10% by weight, further preferably 15% by weight, particularly preferably 20% by weight, and most preferably 25% by weight.

[0029] The nitrile monomer preferably contains acrylonitrile and / or methacrylonitrile, since the expansion performance is improved. When the nitrile monomer contains acrylonitrile, the weight ratio of acrylonitrile in the nitrile monomer is not particularly limited, but is preferably 5% by weight or more. The upper limit of the weight ratio of acrylonitrile in the nitrile monomer is preferably 100% by weight, more preferably 90% by weight, and even more preferably 80% by weight. On the other hand, the lower limit of the weight ratio of acrylonitrile in the nitrile monomer is more preferably 10% by weight, and particularly preferably 20% by weight. When the nitrile monomer contains methacrylonitrile, the weight ratio of methacrylonitrile in the nitrile monomer is not particularly limited, but is preferably 5% by weight or more. The upper limit of the weight ratio of methacrylonitrile in the nitrile monomer is preferably 100% by weight, more preferably 90% by weight, and particularly preferably 80% by weight. On the other hand, the lower limit of the weight ratio of methacrylonitrile in the nitrile monomer is more preferably 10% by weight, and particularly preferably 20% by weight.

[0030] The polymerizable component may further contain a carboxyl group-containing monomer as a monomer component, which is preferred because it improves the heat resistance of the heat-expandable microspheres. When the polymerizable component contains a carboxyl group-containing monomer, the weight ratio of the carboxyl group-containing monomer in the polymerizable component is not particularly limited, but is preferably 5 to 90% by weight. When the weight ratio of the carboxyl group-containing monomer is 5% by weight or more, the heat resistance tends to be improved, and when it is 90% by weight or less, the expansion performance tends to be improved. The upper limit of the weight ratio of the carboxyl group-containing monomer is more preferably 85% by weight, even more preferably 75% by weight, particularly preferably 70% by weight, and most preferably 65% ​​by weight. On the other hand, the lower limit of the weight ratio of the carboxyl group-containing monomer is more preferably 10% by weight, even more preferably 15% by weight, particularly preferably 20% by weight, and most preferably 25% by weight.

[0031] The polymerizable component may further contain a vinylidene halide monomer as a monomer component, which is preferable because it improves the gas barrier properties of the thermoplastic resin constituting the shell of the heat-expandable microspheres. When the polymerizable component contains a vinylidene halide monomer, the weight ratio of the vinylidene halide monomer in the polymerizable component is not particularly limited, but is preferably 5 to 80% by weight. When the weight ratio of the vinylidene halide monomer is within the above range, the expansion performance tends to be improved. The upper limit of the weight ratio of the vinylidene halide monomer is more preferably 75% by weight, even more preferably 70% by weight, particularly preferably 65% ​​by weight, and most preferably 60% by weight. The lower limit of the weight ratio of the vinylidene halide monomer is more preferably 10% by weight, even more preferably 15% by weight, particularly preferably 20% by weight, and most preferably 25% by weight.

[0032] The polymerizable component may contain a crosslinking agent as described above. By using a crosslinking agent for polymerization, the heat-expandable microspheres obtained can be effectively expanded by heat since the retention rate of the encapsulated blowing agent during thermal expansion is prevented from decreasing. The crosslinking agent is not particularly limited, and examples thereof include aromatic divinyl compounds such as divinylbenzene; allyl methacrylate, triacrylformal, triallyl isocyanate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene 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, Examples of the crosslinking agent include polyfunctional (meth)acrylate compounds such as ol 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, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, and tricyclodecane dimethanol di(meth)acrylate. These crosslinking agents may be used alone or in combination of two or more.

[0033] The crosslinking agent may be omitted, but there is no particular limitation on the amount thereof, which is preferably 0 to 5.0 parts by weight, more preferably 0.01 to 3.0 parts by weight, further preferably 0.02 to 2.0 parts by weight, and particularly preferably 0.05 to 1.5 parts by weight, based on 100 parts by weight of the monomer component. If the content of the crosslinking agent exceeds 5.0 parts by weight, the expansion performance of the heat-expandable microspheres may decrease.

[0034] The blowing agent is a component that vaporizes when heated. When the blowing agent is encapsulated in the thermoplastic resin shell of the heat-expandable microspheres, the heat-expandable microspheres as a whole exhibit heat expandability (the property that the entire microsphere expands when heated).

[0035] The blowing agent is not particularly limited, and examples thereof include linear hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, nonane, decane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, and nanodecane; isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, isododecane, 3-methylundecane, isotridecane, 4-methyldodecane, isotetradecane, isopentadecane, isohexadecane, 2,2,4,4,6,8,8-heptamethylnonane, isoheptadecane, and isooctadecane. Examples of the foaming agent include branched hydrocarbons such as isonadecane and 2,6,10,14-tetramethylpentadecane; hydrocarbons such as cyclododecane, cyclotridecane, hexylcyclohexane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, and octadecylcyclohexane; petroleum ether; halides thereof; fluorine-containing compounds such as hydrofluoroether; tetraalkylsilane; and compounds that are thermally decomposed by heating to generate gas. The foaming agent may be linear, branched, or alicyclic, and is preferably aliphatic. These foaming agents may be used alone or in combination of two or more.

[0036] The average particle size of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 0.5 to 200 μm, more preferably 1 to 150 μm, even more preferably 1.5 to 100 μm, particularly preferably 2 to 75 μm, and most preferably 5 to 50 μm. When the average particle size is 0.5 μm or more, the heat-expandable microspheres tend to have high expansion performance, and when the average particle size is 200 μm or less, the heat-expandable microspheres tend to have high expansion stability.

[0037] The coefficient of variation CV of the particle size distribution of the heat-expandable microspheres is not particularly limited, but is preferably not more than 50%, more preferably not more than 45%, and particularly preferably not more than 40%. The coefficient of variation CV is calculated by the following formulas (1) and (2).

[0038]

number

[0039] The encapsulation rate of the blowing agent is defined as the percentage of the weight of the blowing agent encapsulated in the heat-expandable microspheres relative to the weight of the heat-expandable microspheres. The encapsulation rate of the blowing agent is not particularly limited, but is preferably 1 to 50% by weight, more preferably 2 to 45% by weight, further preferably 5 to 40% by weight, and particularly preferably 10 to 35% by weight.

[0040] The expansion start temperature of thermally expandable microspheres (T s ) is not particularly limited, but is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, particularly preferably 130°C or higher, and most preferably 150°C or higher. If the expansion initiation temperature of heat-expandable microspheres is lower than 100°C, sufficient heat resistance may not be obtained. The upper limit of the expansion initiation temperature of heat-expandable microspheres is preferably 300°C. Maximum expansion temperature of thermally expandable microspheres (T max ) is not particularly limited, but is preferably 150° C. or higher, more preferably 170° C. or higher, even more preferably 180° C. or higher, particularly preferably 190° C. or higher, and most preferably 200° C. or higher. The upper limit of the maximum expansion temperature is preferably 350° C. If the maximum expansion temperature of the heat-expandable microspheres is lower than 150° C., sufficient heat resistance may not be obtained, and if it exceeds 350° C., a sufficient expansion ratio may not be obtained.

[0041] The heat-expandable microspheres of the present invention have excellent heat resistance and high expansion properties, and are therefore suitable for use in molding processes such as injection molding, extrusion molding, press molding, kneading molding, calendar molding, blow molding, compression molding, vacuum molding, thermoforming, etc. They can also be used by mixing with paste-like materials such as PVC paste, or liquid compositions such as EVA emulsion, acrylic emulsion, and solvent-based binders.

[0042] The maximum volume expansion ratio (R ex ) is not particularly limited, but is preferably 3 times or more, more preferably 10 times or more, even more preferably 20 times or more, particularly preferably 30 times or more, even more preferably 50 times or more, and most preferably 70 times or more. On the other hand, the upper limit of the maximum expansion ratio is preferably 200 times.

[0043] [Method of producing heat-expandable microspheres] The method for producing heat-expandable microspheres of the present invention comprises the steps of dispersing a polymerizable component, which includes a monomer (A) having a hydroxyl group, a lactone ring, and one polymerizable carbon-carbon double bond, and a blowing agent in an aqueous dispersion medium, and polymerizing the polymerizable component (hereinafter sometimes simply referred to as a polymerization step). The monomer (A), polymerizable component, and blowing agent used in the process for producing heat-expandable microspheres of the present invention are those described above.

[0044] In the method for producing heat-expandable microspheres of the present invention, the polymerizable component may be polymerized in the presence of a polymerization initiator. Use of a polymerization initiator is preferred because heat-expandable microspheres can be produced efficiently. The polymerization initiator is preferably contained in the oily mixture together with the polymerizable component and the blowing agent.

[0045] Examples of the polymerization initiator include peroxides and azo compounds. Examples of peroxides include peroxydicarbonates such as diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and dibenzyl peroxydicarbonate; diacyl peroxides such as lauroyl peroxide and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxyketals such as 2,2-bis(t-butylperoxy)butane; hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide; dialkyl peroxides such as dicumyl peroxide and di-t-butyl peroxide; and peroxy esters such as t-hexyl peroxypivalate and t-butyl peroxyisobutyrate.

[0046] 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), and 1,1'-azobis(cyclohexane-1-carbonitrile). 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 to 5 parts by weight, based on 100 parts by weight of the polymerizable component. When the amount of the polymerization initiator is within the above range, the heat resistance and expansion performance of the obtained heat-expandable microspheres tend to be high.

[0047] In the polymerization process, the aqueous dispersion medium is a medium for dispersing an oily mixture essentially containing a polymerizable component and a blowing agent, and is mainly composed of water such as ion-exchanged water. The aqueous dispersion medium may further contain an alcohol such as methanol, ethanol, or propanol, or a hydrophilic organic solvent such as acetone. In the present invention, hydrophilicity means a state in which the aqueous dispersion medium can be arbitrarily mixed with water. The amount of the aqueous dispersion medium used is not particularly limited, but it is preferable to use 100 to 1000 parts by weight of the aqueous dispersion medium for 100 parts by weight of the polymerizable component.

[0048] 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, sodium carbonate, etc. 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 preferable that the electrolyte is contained in an amount of 0.1 to 50 parts by weight per 100 parts by weight of the aqueous dispersion medium.

[0049] The aqueous dispersion medium may contain at least one water-soluble compound selected from 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 heteroatom are bonded to the same carbon atom, potassium dichromate, alkali metal nitrite, metal (III) halide, boric acid, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble B vitamins, and water-soluble phosphonic acids (salts). In the present invention, water-soluble means a state in which 1 g or more is dissolved in 100 g of water.

[0050] 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 0.1 parts by weight, and particularly preferably 0.001 to 0.05 parts by weight, relative to 100 parts by weight of the polymerizable component. If the amount of the water-soluble compound is too small, the effect of the water-soluble compound may not be sufficiently obtained. If the amount of the water-soluble compound is too large, the polymerization rate may decrease or the amount of the polymerizable component remaining as the raw material may increase.

[0051] The aqueous dispersion medium may contain a dispersion stabilizer or a dispersion stabilization assistant in addition to the electrolyte and the water-soluble compound. Examples of the dispersion stabilizer include tribasic calcium phosphate, magnesium pyrophosphate obtained by a double decomposition method, calcium pyrophosphate, colloidal silica, alumina sol, magnesium hydroxide, etc. These dispersion stabilizers may be used alone or in combination of two or more kinds. The amount of the dispersion stabilizer is preferably 0.05 to 30 parts by weight, and more preferably 0.2 to 20 parts by weight, based on 100 parts by weight of the polymerizable component.

[0052] The dispersion stabilization assistant is not particularly limited, and examples thereof include polymer-type dispersion stabilization assistants, cationic surfactants, anionic surfactants, amphoteric surfactants, nonionic surfactants, etc. These dispersion stabilization assistants may be used alone or in combination of two or more kinds.

[0053] 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 assistant. The pH of the aqueous dispersion medium during polymerization is appropriately determined depending on the types of the water-soluble compound, the dispersion stabilizer, and the dispersion stabilization assistant. Specifically, when colloidal silica is used as the dispersion stabilizer, the pH is preferably adjusted to the acidic range, and when magnesium hydroxide is used as the dispersion stabilizer, the pH is preferably adjusted to the alkaline range.

[0054] In the polymerization step, a chain transfer agent, an organic pigment, an inorganic pigment or inorganic particles whose surface has been treated for hydrophobicity, etc. may be further used, and the polymerization may be carried out in the presence of sodium hydroxide, or sodium hydroxide and zinc chloride.

[0055] In the polymerization step, the oily mixture is suspended and dispersed in an aqueous dispersion medium so as to prepare spherical oil droplets having a predetermined particle size. Examples of methods for suspending and dispersing an oily mixture include general dispersion methods such as stirring with a homomixer (e.g., manufactured by Primix Corporation) or the like, a method using a static dispersion device such as a static mixer (e.g., manufactured by Noritake Co., Ltd.), a membrane emulsification method, and an ultrasonic dispersion method. The aqueous suspension in which the oily mixture is dispersed in the aqueous dispersion medium as oil globules is then heated to initiate suspension polymerization. During the polymerization reaction, the aqueous suspension is preferably stirred, and the stirring may be carried out gently enough to prevent the floating of the monomer components and the settling of the heat-expandable microspheres after polymerization.

[0056] The polymerization temperature is 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 is 0 to 5.0 MPa, more preferably 0.1 to 3.0 MPa, in terms of gauge pressure.

[0057] [Hollow particles] The resin hollow particles of the present invention are particles obtained by thermally expanding the above-mentioned heat-expandable microspheres or the heat-expandable microspheres obtained by the above-mentioned method for producing heat-expandable microspheres. The resin hollow particles are lightweight and have excellent material properties when incorporated into a composition or molded article. The resin hollow particles of the present invention are particles obtained by thermally expanding the above-mentioned heat-expandable microspheres or the heat-expandable microspheres obtained by the above-mentioned method for producing heat-expandable microspheres. Since the resin hollow particles of the present invention are made of a shell made of a thermoplastic resin obtained by polymerizing a specific polymerizable component, they have excellent dispersibility when mixed with a base component.

[0058] The resin hollow particles of the present invention can be produced by thermally expanding the above-mentioned heat-expandable microspheres and / or the heat-expandable microspheres obtained by the method for producing heat-expandable microspheres. There are no particular limitations on the thermal expansion method, and either a dry thermal expansion method or a wet thermal expansion method may be used. The dry thermal expansion method includes the method described in JP-A-2006-213930, particularly the internal injection method. Another dry thermal expansion method includes the method described in JP-A-2006-96963. The wet thermal expansion method includes the method described in JP-A-62-201231.

[0059] The average particle size of the resin hollow particles is not particularly limited, but is preferably 1 to 1000 μm, more preferably 5 to 800 μm, and particularly preferably 10 to 500 μm. The coefficient of variation CV of the particle size distribution of the resin hollow particles is not particularly limited, but is preferably 50% or less, and more preferably 40% or less.

[0060] The true specific gravity of the hollow resin particles is not particularly limited, but is preferably 0.005 to 0.6, more preferably 0.015 to 0.4, and particularly preferably 0.020 to 0.3. If the true specific gravity of the hollow particles is 0.005 or more, the particles tend to have sufficient durability, and if the true specific gravity is 0.6 or less, a lightweight molded product tends to be obtained without increasing the amount of hollow particles added when preparing a composition.

[0061] The microparticle-coated hollow resin particles of the present invention are composed of the above-mentioned hollow resin particles and microparticles that are attached to the outer surface of the shell of the hollow resin particles. As an example, the microparticle-coated hollow resin particles may be composed of microparticles (4 or 5) that are attached to the outer surface of the shell (2) of the hollow resin particle, as shown in FIG. The term "adhesion" as used here means that the particulate filler (4 and 5) may simply be adsorbed (4) onto the outer surface of the shell (2) of the hollow particle (1) to which the particulates are attached in a manner such that the particulate filler (4 and 5) is adsorbed onto the outer surface of the shell (2) of the hollow particle to which the particulates are attached in a manner such that the particulates are embedded and fixed to the outer surface of the shell ... The fine particle-coated hollow particles can improve the workability (handling) during use and the dispersibility in a substrate.

[0062] The shape of the fine particles may be amorphous or spherical, for example, spherical, needle-like, or plate-like. The material of the fine particles is not particularly limited, and may be either an inorganic material or an organic material. The average particle size of the fine particles is appropriately selected depending on the hollow particle body used and is not particularly limited, but is preferably 0.001 to 30 μm, more preferably 0.005 to 25 μm, and particularly preferably 0.01 to 20 μm. The average particle size of the fine particles is preferably 1 / 10 or less of the average particle size of the fine particle-coated hollow particles, where the average particle size of the fine particles means the average particle size of the primary particles.

[0063] The microparticle-coated hollow particles can be obtained, for example, by heating and expanding the microparticle-coated heat-expandable microspheres. A preferred method for producing the microparticle-coated hollow particles includes a step of mixing the heat-expandable microspheres with the microparticles (mixing step) and a step of heating the mixture obtained in the mixing step to a temperature exceeding the softening point of the thermoplastic resin that constitutes the shell, thereby expanding the heat-expandable microspheres and adhering the microparticles to the outer surfaces of the obtained hollow particles (adhering step).

[0064] The true specific gravity of the fine particle-coated hollow particles is not particularly limited, but is preferably 0.01 to 0.6, more preferably 0.03 to 0.5, particularly preferably 0.05 to 0.4, and most preferably 0.07 to 0.35. When the fine particle-coated hollow particles have a true specific gravity of 0.01 or more, they tend to have sufficient durability, and when the hollow particles are 0.6 or less, when a composition is prepared using the hollow particles, a lightweight molded product tends to be obtained without increasing the amount of the hollow particles added.

[0065] [Composition and Molded Article] The composition of the present invention contains at least one particulate material selected from the group consisting of the heat-expandable microspheres of the present invention, the heat-expandable microspheres obtained by the method for producing heat-expandable microspheres of the present invention, the hollow particles of the present invention and the microparticle-coated hollow particles of the present invention, and a base component. The base material component is not particularly limited, and examples thereof include rubbers such as natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber, silicone rubber, acrylic rubber, urethane rubber, fluororubber, and ethylene-propylene-diene rubber (EPDM); thermosetting resins such as epoxy resins, phenolic resins, unsaturated polyester resins, and polyurethane; waxes such as polyethylene wax and paraffin wax; ethylene-vinyl acetate copolymers (EVA), polyethylene, modified polyethylene, polypropylene, modified polypropylene, modified polyolefins, polyvinyl chloride (PVC), acrylic resins, thermoplastic polyurethanes, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), polystyrene (PS), and polyamide resins (nylon 6, nylon 66, etc.). thermoplastic resins such as modified polyamide, polycarbonate, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyacetal (POM), polyphenylene sulfide (PPS), polyphenylene ether (PPE), modified polyphenylene ether; ionomer resins such as ethylene-based ionomer, urethane-based ionomer, styrene-based ionomer, fluorine-based ionomer; thermoplastic elastomers such as olefin-based elastomer, styrene-based elastomer, polyester-based elastomer; bioplastics such as polylactic acid (PLA), cellulose acetate, PBS, PHA, starch resin; sealing materials such as modified silicone, urethane, polysulfide, acrylic, silicone, polyisobutylene, butyl rubber; urethane, ethylene-vinyl acetate copolymer, vinyl chloride, acrylic paint components; and inorganic materials such as cement, mortar, and cordierite.

[0066] The composition of the present invention can be prepared by mixing these base components with at least one particulate material selected from the group consisting of heat-expandable microspheres, hollow particles, and hollow particles coated with fine particles. The composition obtained by mixing the base component with the particulate material can also be mixed with another base component to prepare the composition of the present invention. The weight ratio of the granular material to 100 parts by weight of the base component is preferably 0.1 to 70 parts by weight, more preferably 0.5 to 65 parts by weight, and further preferably 1 to 60 parts by weight.

[0067] The method for mixing the base component and the granular material is not particularly limited, but it is preferable to mix them using a kneader, roll, mixing roll, mixer, single-screw kneader, twin-screw kneader, multi-screw kneader, or the like. The applications of the composition of the present invention include, for example, molding compositions, coating compositions, clay compositions, fiber compositions, and the like. Examples of the composition include fiber compositions, adhesive compositions, and powder compositions.

[0068] The molded article of the present invention is obtained by molding the above-mentioned composition. Examples of the molded article of the present invention include molded articles such as molded products and coating films. The molded article of the present invention has improved physical properties such as light weight, porosity, sound absorption, heat insulation, low thermal conductivity, low dielectric constant, design, impact absorption, and strength. The molded article of the present invention is lightweight since it is obtained by molding the above composition. EXAMPLES

[0069] Examples of the heat-expandable microspheres of the present invention are described below in detail. However, 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. The heat-expandable microspheres described in the following Examples and Comparative Examples were measured for physical properties and evaluated for performance in the following manner. Hereinafter, the heat-expandable microspheres will sometimes be referred to as "microspheres" for simplicity.

[0070] [Measurement of average particle size (D50) and particle size distribution of heat-expandable microspheres] The measurement device used was a Microtrac particle size distribution meter (model 9320-HRA) manufactured by Nikkiso Co., Ltd., and the D50 value based on volumetric measurement was taken as the average particle size.

[0071] [Expansion start temperature of thermally expandable microspheres (T s ), maximum displacement (H max ) and maximum expansion temperature (T max Measurement of A DMA (DMA Q800, manufactured by TA Instruments) was used as the measuring device. 0.5 mg of 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 microsphere layer to prepare a sample. The sample height was measured while a force of 0.01 N was applied from above using a pressure rod. With a force of 0.01 N applied using the pressure rod, the sample was heated from 20°C to 300°C at a heating rate of 10°C / min, and the displacement of the pressure rod in the vertical direction was measured. The temperature at which displacement in the forward direction began was defined as the expansion beginning temperature (T s ) and the maximum displacement (H max ) is the maximum expansion temperature (T max ) was selected. max And T max A high value indicates excellent heat resistance and high expansion properties.

[0072] [Maximum volume expansion ratio of heat-expandable microspheres (R ex )〕 The maximum displacement (H max ) The maximum volume expansion ratio is calculated using the following formula. d bulk : Bulk density of heat-expandable microspheres: 0.0004 (g / mm 3 ) R ex ={((H max (μm) / 1000)×(5.6(mm) / 2) 2 ×π) / (0.0005 / d bulk )} (1 / 3)

[0073] [Water content of thermally expandable microspheres (C w1 Measurement of The measurement was performed using a Karl Fischer moisture meter (Model MKA-510N, manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The moisture content (wt%) of the heat-expandable microspheres was measured using w1 It was decided.

[0074] [Measurement of the encapsulation rate (C1) of the blowing agent in heat-expandable microspheres] 1.0 g of the heat-expandable microspheres were placed in a stainless steel evaporating dish with a diameter of 80 mm and a depth of 15 mm, and its weight (W1(g)) was measured. 30 ml of acetonitrile was added to disperse the microspheres uniformly, and the microspheres were left at room temperature for 24 hours, and then dried under reduced pressure at 130°C for 2 hours, after which their weight (W2(g)) was measured. The encapsulation rate (C1) of the blowing agent in the heat-expandable microspheres is calculated by the following formula: C1(weight%)=100×{100×(W1-W2) / 1.0-C w1 } / (100-C w1 ) (In the formula, the water content of thermally expandable microspheres C w1 is measured by the above method.)

[0075] <Example 1> An aqueous dispersion medium was prepared by dissolving 130 parts of sodium chloride in 500 parts of ion-exchanged water, adding 1.0 part of polyvinylpyrrolidone, 0.05 part of carboxymethylated polyimine Na salt, and 65 parts of colloidal silica (effective concentration 20%), and adjusting the pH to 3.0. Separately from this, 24 parts of α-methylene-β-hydroxy-γ-butyrolactone, 136 parts of acrylonitrile, 70 parts of methacrylonitrile, 10 parts of methyl methacrylate, 0.95 parts of ethylene glycol dimethacrylate, 3.0 parts of di-2-ethylhexyl peroxydicarbonate, 0.50 parts of dilauroyl peroxide, 15 parts of 2-methylpentane (isobutane), and 55 parts of 2-methylbutane (isopentane) were mixed and dissolved to obtain an oily mixture. The aqueous dispersion medium and the oil mixture were mixed, and the resulting mixture was dispersed for 1 minute at a rotation speed of 10,000 rpm using a homomixer (TK homomixer, manufactured by Primix Corporation) to prepare an aqueous suspension. The resulting aqueous suspension was transferred to a 1.5 L pressure reactor and purged with nitrogen. The initial reaction pressure was adjusted to 0.35 MPa, and the mixture was polymerized at 60°C for 20 hours while stirring at 80 rpm. After polymerization, the product was filtered and dried to obtain heat-expandable microspheres. The physical properties of the resulting heat-expandable microspheres are shown in Table 1.

[0076] <Examples 2 to 6 and Comparative Examples 1 to 4> In Examples 2 to 6, heat-expandable microspheres were obtained in the same manner as in Example 1, except that the procedures were changed as shown in Table 1. On the other hand, in Comparative Examples 1 to 4, heat-expandable microspheres were obtained in the same manner as in Example 1, except that the monomer (A) was not used and the procedures were changed as shown in Table 2. The physical properties of the resulting heat-expandable microspheres were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0077] [Table 1]

[0078] [Table 2]

[0079] The thermally expandable particles of Examples 1 to 6, which use the monomer (A) having a hydroxyl group, a lactone ring, and one polymerizable carbon-carbon double bond, are max And T max It is clear that the material has excellent heat resistance and high expansion performance. In contrast, the heat-expandable microspheres of Comparative Examples 1 to 4, which did not contain the monomer (A), max and T max It can be seen that at least one of these is low, and the heat resistance and / or expansion performance is poor. [Industrial Applicability]

[0080] The heat-expandable microspheres of the present invention can be used as a lightweight material for putty, paint, ink, sealant, mortar, paper clay, pottery, etc., and can also be used together with a base component to produce molded articles having excellent sound insulation, heat insulation, heat insulation, sound absorption, etc. [Explanation of symbols]

[0081] 1 Hollow particles with fine particles attached 2. Outer shell 3 Hollow part 4. Microparticles (adsorbed state) 5. Microparticles (embedded and fixed) 6. Shell made of thermoplastic resin 7 Foaming agent (core)< / x>

Claims

1. The outer shell is made of thermoplastic resin and the foam inside is vaporized by heating. and a heat-expandable microsphere comprising: the thermoplastic resin is a polymer of a polymerizable component containing a monomer (A), The monomer (A) is α-methylene-β-hydroxy-γ-butyrolactone, The weight ratio of the monomer (A) to the polymerizable component is 5 to 90% by weight.

2. The heat-expandable microspheres according to claim 1, wherein the polymerizable component further comprises a nitrile monomer.

3. A method for producing heat-expandable microspheres which are composed of an outer shell made of a thermoplastic resin and a blowing agent encapsulated therein and vaporized by heating, comprising the steps of: The method includes a step of dispersing a polymerizable component and the foaming agent in an aqueous dispersion medium, and polymerizing the polymerizable component, the polymerizable component comprises a monomer (A), The monomer (A) is α-methylene-β-hydroxy-γ-butyrolactone, The weight ratio of the monomer (A) in the polymerizable component is 5 to 90% by weight.

4. 3. A hollow resin particle which is an expanded product of the heat-expandable microspheres according to claim 1 or 2.

5. 5. A microparticle-attached hollow resin particle comprising the hollow resin particle according to claim 4 and microparticles attached to the outer surface of the outer shell of the hollow resin particle.

6. 10. A composition comprising at least one member selected from the group consisting of the heat-expandable microspheres according to claim 1 or 2, the hollow resin particles according to claim 4, and the microparticle-coated hollow resin particles according to claim 5, and a base component.

7. A molded article obtained by molding the composition according to claim 6.

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