Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
  • B01J13/02—Making microcapsules or microballoons
  • B01J13/06—Making microcapsules or microballoons by phase separation
  • B01J13/14—Polymerisation; cross-linking
  • B01J13/16—Interfacial polymerisation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/32—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof from compositions containing microballoons, e.g. syntactic foams
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere

Definitions

• the present invention relates to heat-expandable microspheres and their uses.
• Heat-expandable microspheres are fine particles that expand when heated, and are used in a wide range of applications, such as design additives for foaming inks and wallpapers, and weight-reducing agents for resins and paints.
• Heat-expandable microspheres are widely known as microparticles having a thermoplastic resin shell and encapsulating an expanding agent whose boiling point is equal to or lower than the softening point of the thermoplastic resin constituting the shell.
• Patent Document 1 discloses microspheres using a vinylidene chloride copolymer, an acrylonitrile copolymer, or an acrylic ester copolymer as the thermoplastic resin and a hydrocarbon such as isobutane or isopentane as the expanding agent.
• Patent Document 2 discloses heat-expandable microspheres containing isododecane as the expanding agent and exhibiting expandability after heating at 150°C for 5 minutes.
• Heat-expandable microspheres are generally used by blending them with other base materials and expanding the blend when the blend is heated, which allows the base material to have design properties, cushioning properties, etc., and to be made lighter.
• the heating process may require multiple heating steps, and heat-expandable microspheres whose expandability does not decrease even after multiple heating steps are desired.
• the heat-expandable microspheres disclosed in Patent Document 1 can be efficiently expanded at a relatively low heating temperature, at higher temperatures or for long heating times, their heat resistance is insufficient, causing a phenomenon known as "settlement,” in which they significantly shrink upon heating, resulting in insufficient expandability.
• the heat-expandable microspheres disclosed in Patent Document 2 are expandable even after heating at 150°C for 5 minutes, but their expandability decreases with prolonged heating times, making it impossible to maintain sufficient expandability.
• the object of the present invention is to provide heat-expandable microspheres that maintain high expandability even when heated for long periods of time, and uses thereof.
• the present inventors have found that the above problems can be solved by using heat-expandable microspheres containing a specific substance, and have arrived at the present invention. That is, the present invention includes the following aspects.
• Heat-expandable microspheres comprising a thermoplastic resin and a siloxane-based substance (A) that volatilizes in an amount of 2% by weight or more when heated at 150°C for 24 hours, the substance (A) being encapsulated within the heat-expandable microspheres.
• ⁇ 3> Heat-expandable microspheres according to ⁇ 1> or ⁇ 2>, wherein the substance (A) is at least one selected from the group consisting of organodisiloxanes, organotrisiloxanes, and organopolysiloxanes.
• thermoplastic resin is a polymer of a polymerizable component containing at least one monomer selected from the group consisting of a nitrile monomer, a carboxyl group-containing monomer, a (meth)acrylic acid ester monomer, a styrene monomer, a (meth)acrylamide monomer, and a vinylidene halide monomer.
• the thermoplastic resin is a polymer of a polymerizable component containing at least one monomer selected from the group consisting of a nitrile monomer, a carboxyl group-containing monomer, a (meth)acrylic acid ester monomer, a styrene monomer, a (meth)acrylamide monomer, and a vinylidene halide monomer.
• Hollow particles which are expanded bodies of the heat-expandable microspheres according to any one of ⁇ 1> to ⁇ 5>.
• Microparticle-coated hollow particles comprising the hollow particles according to ⁇ 6> and microparticles attached to the outer surface of the outer shell of the hollow particles.
• a composition comprising at least one selected from the heat-expandable microspheres described in any one of ⁇ 1> to ⁇ 5>, the hollow particles described in ⁇ 6>, and the fine-particle-coated hollow particles described in ⁇ 7>, and a base component.
• ⁇ 9> A molded article obtained by molding the composition according to ⁇ 8>.
• the heat-expandable microspheres of the present invention maintain high expandability even when heated for a long period of time.
• the hollow particles of the present invention are expanded versions of the heat-expandable microspheres, and therefore are lightweight with reduced shrinkage.
• the fine particle-coated hollow particles of the present invention contain the above hollow particles, and therefore are lightweight with reduced shrinkage.
• the composition of the present invention contains at least one selected from the group consisting of the heat-expandable microspheres, the hollow particles, and the fine particle-coated hollow particles, and therefore allows for the stable production of lightweight molded articles.
• the molded article of the present invention is obtained by molding the above composition, and is therefore lightweight and has excellent heat resistance.
• FIG. 1 is a schematic diagram illustrating an example of heat-expandable microspheres.
• FIG. 2 is a schematic diagram showing an example of fine particle-coated hollow particles.
• the heat-expandable microspheres of the present invention contain a thermoplastic resin and a siloxane-based substance (A) that volatilizes by 2% by weight or more when heated at 150°C for 24 hours, and the microspheres encapsulate the siloxane-based substance (A).
• the microspheres as a whole exhibit heat expandability (the property that the entire microspheres expand when heated).
• the heat-expandable microspheres of the present invention may be in the following embodiment 1 or embodiment 2.
• Aspect 1 A shell containing a thermoplastic resin and a physical substance (A) contained in the shell.
• Aspect 2 A shell containing two or more pores in the thermoplastic resin, and the pores containing the substance (A).
• the embodiment 1 has a core-shell structure having an outer shell 6 containing a thermoplastic resin and a core 7 containing the substance (A) as shown in FIG. Furthermore, when the microspheres of the present invention are those of embodiment 1, the effects of the present invention are exhibited, and the hollow particles, which are expanded bodies of the microspheres, are preferred in that they have elasticity.
• Thermoplastic resins are resins that have the property of softening when heated.
• the thermoplastic resin is not particularly limited, but examples thereof include acrylic resins, acrylic acid resins, nitrile resins, vinyl chloride resins, vinylidene chloride resins, urethane resins, styrene resins, amide resins, ester resins, ether resins, olefin resins, cellulose resins, etc. These thermoplastic resins may be used alone or in combination of two or more, or may be copolymers.
• the thermoplastic resin preferably contains at least one selected from an acrylic resin, an acrylic acid resin, a nitrile resin, a vinylidene chloride resin, a styrene resin, and an amide resin, and more preferably a copolymer of these.
• the thermoplastic resin is preferably a polymer obtained by polymerizing a polymerizable component.
• the polymerizable component includes a monomer component and may include a crosslinking agent.
• the monomer component refers to a polymerizable monomer having one polymerizable double bond and is capable of addition polymerization.
• the crosslinking agent refers to a polymerizable monomer having multiple polymerizable double bonds and is a component capable of introducing a crosslinked structure into a thermoplastic resin.
• the monomer components are not particularly limited, but examples include nitrile monomers such as acrylonitrile, methacrylonitrile, and fumaronitrile; carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, maleic acid, itaconic acid, fumaric acid, citraconic acid, and chloromaleic acid; 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; methyl (meth)acrylate, ethyl ( (meth)acrylic acid ester monomers such as butyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate
• Suitable monomers include maleimide-based monomers such as diisohexylmaleimide; styrene-based monomers such as styrene and ⁇ -methylstyrene; ethylenically unsaturated monoolefin-based monomers such as ethylene, propylene, and isobutylene; vinyl ether-based monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; vinyl ketone-based monomers such as vinyl methyl ketone; N-vinyl-based monomers such as N-vinylcarbazole and N-vinylpyrrolidone; and vinyl naphthalene salts. These monomers may be used alone or in combination of two or more.
• (Meth)acrylic refers to either acrylic or methacrylic.
• the polymerizable component contains at least one selected from nitrile-based monomers, carboxyl group-containing monomers, (meth)acrylic acid ester-based monomers, styrene-based monomers, vinyl ester-based monomers, acrylamide-based monomers, and vinylidene halide-based monomers.
• the polymerizable component preferably contains a carboxyl group-containing monomer as a monomer component, since the resulting heat-expandable microspheres have improved heat resistance.
• Acrylic acid and methacrylic acid are preferred as carboxyl group-containing monomers because they are readily available and further improve heat resistance.
• some or all of the carboxyl groups in the carboxyl group-containing monomer may be in the form of a carboxyl salt during or after polymerization.
• the weight ratio of the carboxyl group-containing monomer in the polymerizable component is not particularly limited, but is preferably 5 to 70% by weight, more preferably 10 to 65% by weight, even more preferably 20 to 60% by weight, and particularly preferably 30 to 55% by weight.
• the polymerizable component may further contain a monomer having a group reactive with a carboxyl group as a monomer component.
• the polymerizable component containing a monomer having a group reactive with a carboxyl group is preferred because it improves the heat resistance of the resulting heat-expandable microspheres.
• the group that reacts with a carboxyl group is not particularly limited, but examples thereof include a methylol group, a hydroxyl group, an amino group, an epoxy group, and an isocyanate group.
• the monomer having a group reactive with a carboxyl group is not particularly limited, and examples thereof include N-methylol(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylate, N,N-dimethylaminopropyl(meth)acrylate, vinyl glycidyl ether, propenyl glycidyl ether, glycidyl(meth)acrylate, glycerin mono(meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 2-hydroxy-3-phenoxypropy
• the polymerizable component contains vinylidene chloride as a monomer component, since this improves the gas barrier properties. It is preferable that the polymerizable component contains at least one selected from a (meth)acrylic acid ester monomer and a styrene monomer as a monomer component, since this makes it easier to control the thermal expansion characteristics. It is preferable that the polymerizable component contains a (meth)acrylamide monomer as a monomer component, since this improves heat resistance.
• the polymerizable component may contain a crosslinking agent, which is preferable in terms of improving heat resistance.
• the crosslinking agent is not particularly limited, and examples thereof include alkanediol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5 pentanediol di(meth)acrylate, and 2-methyl-1,8 octanediol di(meth)acrylate; diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, PEG #200 di(meth)acrylate
• thermoplastic resin in the heat-expandable microspheres there are no particular restrictions on the weight percentage of the thermoplastic resin in the heat-expandable microspheres, but it is preferably 10 to 99% by weight, more preferably 20 to 98% by weight, even more preferably 30 to 97% by weight, particularly preferably 40 to 95% by weight, and most preferably 50 to 95% by weight.
• the heat-expandable microspheres of the present invention may be surface-treated with an organic compound containing a metal belonging to Groups 3 to 12 of the periodic table, or may be crosslinked by carboxyl groups and metal ions.
• the heat-expandable microspheres of the present invention may contain a component having thermosetting properties.
• the thermosetting component is not particularly limited, and examples thereof include: thermosetting silicones such as silicone rubber, silicone resin, and silicone oligomer; epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene type epoxy resin, and glycidylamine type epoxy resin; phenol resins such as novolac type phenol resin, resol type phenol resin, and benzylic ether type phenol resin; melamine resin, urea resin, polyimide resin, and bismaleimide resin; and the like, and these may be used alone or in combination of two or more.
• the substance (A) has a structure in which a silicon atom is bonded to an organic group, with the main skeleton being a siloxane bond in which a silicon atom is bonded to an oxygen atom.
• the substance (A) having the above structure tends to remain inside the heat-expandable microspheres, resulting in high expandability. Even when the shell softens due to prolonged heating, the substance (A) is retained inside the shell due to the presence of siloxane bonds, preventing penetration of the shell resin. This allows the heat-expandable microspheres to maintain high expandability even after prolonged heating. Furthermore, the inclusion of substance (A) in the heat-expandable microspheres allows them to maintain high expandability even after reheating.
• organotrisiloxanes such as octamethylcyclotetrasiloxane, dodecamethylcyclohexasiloxane, dodecamethylpentasiloxane, decamethyltetrasiloxane, methylpolysiloxane, methylphenylpolysiloxane, decamethylcyclopentasiloxane, methylhydrogenpolysiloxane, caprylyl methicone, triethoxysilylethyl polydimethylsiloxyethyl dimethicone, triethoxysilylethyl polydimethylsiloxyethylhexyl dimethicone, ethylmethicone, and modified silicone oil; triethoxycaprylylsilane; polymethylhydrosiloxane, and the like, and these may be used alone or in combination of two or more.
• the weight percentage of substance (A) in the heat-expandable microspheres is not particularly limited, but is preferably 1 to 70 wt %, more preferably 3 to 60 wt %, even more preferably 5 to 50 wt %, particularly preferably 8 to 40 wt %, and most preferably 10 to 35 wt %.
• the weight percentage of substance (A) in the heat-expandable microspheres is determined by the method described in the Examples.
• the heat-expandable microspheres of the present invention may contain a substance (B) other than the substance (A), which is a component that volatilizes upon heating.
• the substance (B) is not particularly limited, and examples thereof include linear hydrocarbons such as methane, ethane, 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, and isotridecane.
• branched hydrocarbons such as hexane, 4-methyldodecane, isotetradecane, isopentadecane, isohexadecane, 2,2,4,4,6,8,8-heptamethylnonane, isoheptadecane, isooctadecane, isonadecane, and 2,6,10,14-tetramethylpentadecane; cyclododecane, cyclotridecane, hexylcyclohexane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, and nonylcyclohexane hydrocarbons such as petroleum ether, and petroleum fractions such as normal paraffins and isoparaffins having an initial boiling point of 150 to 260°C and/or a distillation range of 70 to 360°C; halides of hydrocarbons having 1 to 12 carbon atoms such as methyl
• the heat-expandable microspheres of the present invention may contain, in addition to the substance (A), a substance (C) which volatilizes in an amount of less than 2% by weight when heated at 150° C. for 24 hours.
• the volume-average particle size of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 0.1 to 500 ⁇ m, more preferably 0.5 to 300 ⁇ m, even more preferably 1 to 200 ⁇ m, particularly preferably 3 to 100 ⁇ m, and most preferably 5 to 50 ⁇ m.
• the volume-average particle size of the heat-expandable microspheres of the present invention is measured by the method described in the Examples.
• the expansion initiation temperature (Ts) of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 120 to 350°C, more preferably 140 to 340°C, even more preferably 150 to 330°C, and particularly preferably 150 to 320°C.
• the maximum expansion displacement (Hmax1) of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 100 ⁇ m or more, more preferably 200 ⁇ m or more, even more preferably 300 ⁇ m or more, and particularly preferably 500 ⁇ m or more.
• the maximum expansion displacement (Hmax2) of the heat-expandable microspheres of the present invention after heating for 2 hours at a temperature 50°C lower than their expansion-initiation temperature is not particularly limited, but is preferably at least 100 ⁇ m, more preferably at least 200 ⁇ m, even more preferably at least 300 ⁇ m, and particularly preferably at least 500 ⁇ m.
• the maximum expansion displacement of the heat-expandable microspheres of the present invention and the heated product thereof is measured by the method described in the examples.
• the heat-expandable microspheres can also be used by mixing them with paste-like materials such as PVC paste, or liquid compositions such as EVA emulsion, acrylic emulsion, and urethane binder. They can also be incorporated into coatings to create texture and improve design.
• paste-like materials such as PVC paste, or liquid compositions such as EVA emulsion, acrylic emulsion, and urethane binder. They can also be incorporated into coatings to create texture and improve design.
• the method for producing heat-expandable microspheres of the present invention includes, for example, a step of dispersing an oily mixture containing a polymerizable component, the substance (A), and a polymerization initiator in an aqueous dispersion medium and polymerizing the polymerizable component (hereinafter, sometimes simply referred to as a polymerization step).
• the polymerization initiator is not particularly limited, but examples thereof include commonly used peroxides and azo compounds.
• peroxides include peroxydicarbonates such as diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and dibenzyl peroxydicarbonate; diacyl peroxides such as dilauroyl peroxide and dibenzoyl 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 peroxyesters such as t-hexyl peroxypiva
• azo compounds examples 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).
• polymerization initiator used in the amount of polymerization initiator used, but it is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, and even more preferably 0.2 to 5 parts by weight per 100 parts by weight of the polymerizable component.
• aqueous dispersion medium is a medium containing water, such as ion-exchanged water, as its main component, for dispersing the oily mixture, and may further contain an alcohol, such as methanol, ethanol, or propanol, or a hydrophilic organic solvent, such as acetone.
• hydrophilic 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 is preferably 100 to 1,000 parts by weight per 100 parts by weight of the polymerizable component.
• the aqueous dispersion medium may further contain an electrolyte.
• electrolytes 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. There are no particular restrictions on the content of the electrolyte, 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 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, polyalkyleneimines having a structure in which an alkyl group substituted with a hydrophilic functional group selected from a carboxylic acid (salt) group and a phosphonic acid (salt) group is bonded to a nitrogen atom, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble B vitamins, potassium dichromate, alkali metal nitrites, metal (III) halides, boric acid, and water-soluble phosphonic acids (salts).
• water-soluble 1,1-substituted compounds having a structure in which a hydrophilic functional group selected from a hydroxyl group, a
• water-soluble means a state in which 1 g or more of the compound dissolves in 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 part by weight, more preferably 0.0003 to 0.1 part by weight, and even more preferably 0.001 to 0.05 part by weight, relative to 100 parts by weight of the polymerizable component.
• the aqueous dispersion medium may contain a dispersion stabilizer or a dispersion stabilization aid in addition to the electrolyte and the water-soluble compound.
• the dispersion stabilizer is not particularly limited, but examples thereof include tribasic calcium phosphate, magnesium pyrophosphate obtained by a double decomposition method, calcium pyrophosphate, colloidal silica, alumina sol, magnesium hydroxide, and the like, and these dispersion stabilizers may be used alone or in combination of two or more.
• the amount of the dispersion stabilizer to be added is not particularly limited, but is preferably 0.05 to 100 parts by weight, more preferably 0.2 to 70 parts by weight, per 100 parts by weight of the polymerizable component.
• the dispersion stabilization aid is not particularly limited, and examples thereof include polymer-type dispersion stabilization aids, and surfactants such as cationic surfactants, anionic surfactants, zwitterionic surfactants, and nonionic surfactants, and these dispersion stabilization 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 electrolytes, water-soluble compounds, dispersion stabilizers, dispersion stabilization aids, etc. as needed.
• the pH of the aqueous dispersion medium during polymerization is determined appropriately depending on the type of water-soluble compound, dispersion stabilizer, and dispersion stabilization aid.
• the polymerization may be carried out in the presence of sodium hydroxide or sodium hydroxide and zinc chloride.
• an 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 the oily mixture include a method of stirring with a homomixer (e.g., manufactured by Primix Corporation) or the like, a method using a static dispersing device such as a static mixer (e.g., manufactured by Noritake Engineering Co., Ltd.), a membrane suspension method, an ultrasonic dispersion method, and other common dispersion methods.
• the suspension polymerization is then initiated by heating the dispersion in which the oily mixture is dispersed as oil globules in the aqueous dispersion medium.
• the dispersion is preferably stirred, and the stirring may be gentle enough to prevent the floating of the monomers and the settling of the heat-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, and more preferably 40 to 90°C.
• the reaction temperature is preferably maintained for approximately 1 to 20 hours.
• the slurry obtained after the polymerization step is filtered using a centrifuge, a pressure press, a vacuum dehydrator, or the like to form a cake-like substance having a moisture content of 10 to 50% by weight, preferably 15 to 45% by weight, and more preferably 20 to 40% by weight.
• the cake-like substance is then dried using a tray dryer, an indirect heating dryer, a fluidized bed dryer, a vacuum dryer, a vibration dryer, a flash dryer, or the like to form a dry powder having a moisture content of 6% by weight or less, preferably 5% by weight or less, and more preferably 4% by weight or less.
• the cake-like product may be washed with water or redispersed, filtered, and dried.
• the slurry may be dried using a spray dryer, fluidized bed dryer, or the like to obtain a dry powder.
• the hollow particles of the present invention are expanded versions of the heat-expandable microspheres described above.
• the hollow particles are lightweight and exhibit excellent material properties when incorporated into compositions or molded articles.
• the hollow particles of the present invention are not particularly limited, but can be obtained by thermally expanding the above-mentioned heat-expandable microspheres, preferably at a temperature of 100 to 500°C.
• the thermal expansion method is not particularly limited, and either a dry thermal expansion method or a wet thermal expansion method may be used.
• the volume average particle diameter of the hollow particles of the present invention can be freely designed depending on the application and is not particularly limited, but is preferably 0.2 to 3000 ⁇ m, and more preferably 1 to 1000 ⁇ m.
• the true specific gravity of the hollow particles of the present invention is not particularly limited, but is preferably 0.005 to 0.8, more preferably 0.01 to 0.6, even more preferably 0.015 to 0.5, and particularly preferably 0.020 to 0.4.
• the true specific gravity of the hollow particles of the present invention is measured by the method described in the Examples.
• microparticle-coated hollow particles of the present invention comprise the hollow particles described above and microparticles attached to the outer surface of the shell of the hollow particle. As shown in Figure 2, the microparticle-coated hollow particles may be composed of microparticles (4 or 5) attached to the outer surface of the shell 2.
• attached here refers to a state in which the microparticles are simply adsorbed onto the outer surface of the shell 2 of the hollow particle (the state of microparticle 4 in Figure 2), or a state in which the thermoplastic resin forming the shell near the outer surface is melted by heating, causing the microparticles to sink into the outer surface of the shell of the hollow particle and become fixed thereto (the state of microparticle 5 in Figure 2).
• fine particles can be used, and may be made of either inorganic or organic materials.
• the shape of the fine particles may be amorphous or spherical. Examples of the shape of the fine particles include spherical, needle-like, and plate-like.
• the fine particles are not particularly limited, but when the fine particles are organic, examples thereof include metal soaps such as sodium carboxymethylcellulose, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, nitrocellulose, hydroxypropyl cellulose, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, carboxyvinyl polymer, polyvinyl methyl ether, magnesium stearate, calcium stearate, zinc stearate, barium stearate, and lithium stearate; synthetic waxes such as polyethylene wax, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, and hydrogenated castor oil; (meth)acrylic resins, polyamide resins, polyimide resins, urethane resins, polyethylene resins, polypropylene resins, and fluorine-based resins.
• metal soaps such as sodium carboxymethylcellulose, hydroxyethyl cellulose
• the fine particles include talc, mica, clay, bentonite, wollastonite, sericite, kaolin, alumina silicate, pyrophyllite, montmorillonite, carbon black, molybdenum disulfide, tungsten disulfide, graphite fluoride, calcium fluoride, boron nitride, silicon carbide, silica, alumina, mica, colloidal calcium carbonate, calcium silicate, calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, barium sulfate, calcium hydroxide, calcium phosphate, magnesium hydroxide, magnesium phosphate, barium sulfate, titanium dioxide, magnesium oxide, zinc oxide, hydrosaltite, ceramic beads, glass flakes, glass beads, quartz beads, and glass microballoons.
• the inorganic or organic material constituting the fine particles may be treated with a surface treatment agent such as a silane coupling agent, paraffin wax, fatty acid,
• the volume average particle diameter of the microparticles is preferably 1/10 or less of the volume average particle diameter of the microparticle-coated hollow particles.
• average particle diameter refers to the average particle diameter of the primary particles.
• weight percentage of fine particles in the total fine particle-coated hollow particles is preferably 20 to 95% by weight, more preferably 20 to 90% by weight, even more preferably 40 to 85% by weight, and especially preferably 40 to 80% by weight.
• the true specific gravity of the fine particle-coated hollow particles of the present invention is not particularly limited, but is preferably 0.01 to 0.8.
• a true specific gravity of 0.03 or higher tends to suppress deformation of the hollow particles, while a true specific gravity of 0.8 or lower tends to allow them to function more efficiently as a weight-reducing agent.
• the fine particle-coated hollow particles of the present invention are blended with the compositions described below, they are useful as coating compositions or adhesive compositions.
• the fine particle-coated hollow particles can be obtained, for example, by heating and expanding fine particle-coated heat-expandable microspheres.
• a preferred method for producing fine particle-coated hollow particles includes a step of mixing heat-expandable microspheres with fine particles (mixing step), and a step of heating the mixture obtained in the mixing step to a temperature above the softening point to expand the heat-expandable microspheres and to cause fine particles to adhere to the outer surfaces of the resulting hollow particles (adhesion step).
• composition of the present invention contains at least one material selected from the group consisting of the heat-expandable microspheres, hollow particles, and fine particle-coated hollow particles (hereinafter sometimes simply referred to as particulate material), and a base component.
• the base material component is not particularly limited, and examples thereof 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; waxes such as polyethylene wax and paraffin wax; 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), and polybutylene terephthalate.
• rubbers such as natural rubber, butyl rubber, silicone rubber, and ethylene-propylene-diene rubber (EPDM); thermosetting
• thermoplastic resins such as polybutadiene (PBT), polyacetal (POM), polyphenylene sulfide (PPS), etc.; thermoplastic elastomers such as olefin-based elastomers and styrene-based elastomers; bioplastics such as polylactic acid (PLA), cellulose acetate, polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), and starch resins; sealing materials such as silicone-based, modified silicone-based, polysulfide-based, modified polysulfide-based, urethane-based, acrylic-based, polyisobutylene-based, and butyl rubber-based; urethane-based, ethylene-vinyl acetate copolymer-based, vinyl chloride-based, and acrylic coating components; emulsions; and inorganic materials such as cement, mortar, and cordierite, and these base components may be used alone or in combination of two or more.
• PBT polybut
• the composition of the present invention can be prepared by mixing a base component with a granular material.
• the composition obtained by mixing a base component with a granular material can be further mixed with another base component to prepare the composition of the present invention.
• the content of the particulate material is not particularly limited, but is preferably 0.1 to 70 parts by weight, more preferably 0.5 to 65 parts by weight, and even more preferably 1 to 60 parts by weight, per 100 parts by weight of the base component.
• the method for producing the composition of the present invention is not particularly limited, but is preferably a method of mixing using a kneader, roll, mixing roll, mixer, single-screw kneader, twin-screw kneader, multi-screw kneader, or the like.
• the uses of the composition of the present invention are not particularly limited, but examples thereof include molding compositions, coating compositions, clay compositions, fiber compositions, adhesive compositions, and powder compositions.
• 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 coating films and molded articles.
• 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, designability, impact absorption, strength, chipping resistance, etc.
• a molded article containing an inorganic substance as a base component can be further fired to obtain a ceramic filter or the like.
• the sample was heated from 20°C to 400°C at a heating rate of 10°C/min while a force of 0.01 N was applied using the pressure probe, and the displacement of the pressure probe in the vertical direction was measured.
• the temperature at which displacement in the forward direction began was defined as the expansion beginning temperature (Ts), and the temperature at which the maximum expansion displacement (Hmax) was observed was defined as the maximum expansion temperature (Tmax).
• the true specific gravity of the hollow particles was measured by a liquid immersion method (Archimedes method) using isopropyl alcohol in an atmosphere at an ambient temperature of 25° C. and a relative humidity of 50%.
• Example 1 To 600 g of ion-exchanged water were added 150 g of sodium chloride, 50 g of colloidal silica containing 20% by weight of an active ingredient, 4.0 g of polyvinylpyrrolidone, and 1.0 g of ethylenediaminetetraacetic acid tetrasodium salt, and the pH of the resulting mixture was adjusted to 2.0 to 3.0 to prepare an aqueous dispersion medium.
• an oily mixture was prepared by mixing 4 g of acrylonitrile, 114 g of methacrylonitrile, 153 g of methacrylic acid, 15 g of methacrylamide, 15 g of styrene, 0.06 g of 1,9-nonanediol diacrylate, 30 g of decamethyltetrasiloxane (volatilization amount when heated at 150°C for 24 hours: 100 wt%, kinematic viscosity at 25°C: 1.5 mm 2 /s), and 8 g of a liquid containing 50 wt% of di-sec-butyl peroxydicarbonate as an active ingredient.
• the aqueous dispersion medium and the oily mixture were mixed, and the resulting mixture was dispersed in a homomixer to prepare a suspension.
• the suspension was transferred to a 1.5 L pressure reactor and purged with nitrogen.
• the initial reaction pressure was adjusted to 0.2 MPa, and polymerization was carried out at 60°C for 20 hours with stirring.
• the resulting product was filtered and dried to give heat-expandable microspheres 1.
• the resulting heat-expandable microspheres 1 had the same configuration as the above-mentioned configuration 1, and their physical properties were measured to evaluate their expandability. The results are shown in Table 1.
• the heat-expandable microspheres of Examples 1 to 7 expanded well even after prolonged heating, demonstrating excellent expansion retention.
• the heat-expandable microspheres of Comparative Example 1 showed no expansion after prolonged heating, demonstrating poor expansion retention.
• the heat-expandable microspheres of Comparative Example 2 showed neither an expansion initiation temperature nor a maximum expansion temperature, and no expansion was observed. Furthermore, no expansion was observed even after prolonged heating.
• Example A The heat-expandable microspheres 1 obtained in Example 1 were heated in an oven at 200°C for 2 hours and then at 280°C for 2 minutes to obtain hollow particles A.
• the true specific gravity of the obtained hollow particles A was 0.05, indicating that lightweight hollow particles were obtained.
• Heat-expandable microspheres 1 of Example 1 expanded well even after prolonged heating, yielding lightweight hollow particles.
• heat-expandable microspheres 3 of Comparative Example 1 showed reduced expansion after prolonged heating, making it impossible to obtain hollow particles.
• the heat-expandable microspheres of the present invention maintain high expandability even after prolonged heating. Therefore, when a compound containing the heat-expandable microspheres is heated, the compound can maintain its expandability even after multiple heating steps or long-term heating steps. Therefore, the compound can be suitably used in processing steps that involve significant thermal history.
• the heat-expandable microspheres, hollow particles, and microparticle-coated hollow particles of the present invention have excellent heat resistance and can be used as compounding agents in various products such as paints, coating compositions, films, and molded articles.
• Fine particle-adhered hollow particle 2 Outer shell (outer shell) 3 Hollow portion 4 Fine particles (adsorbed state) 5. Microparticles (embedded and fixed) 6. Shell containing thermoplastic resin 7. Core containing substance (A)

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