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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/42—Nitriles
  • C08F220/44—Acrylonitrile
  • C08F220/46—Acrylonitrile with carboxylic acids, sulfonic acids or salts thereof
• • 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
  • 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 thermally expandable microcapsules.
• Patent Document 1 discloses heat-expandable microspheres each comprising an outer shell made of a thermoplastic resin and a blowing agent encapsulated therein that vaporizes upon heating, and the thermoplastic resin includes a nitrile monomer (A) essentially containing methacrylonitrile, a carboxyl group-containing monomer (B), and a monomer (C) having a group reactive with a carboxyl group.
• A nitrile monomer
• B carboxyl group-containing monomer
• C monomer having a group reactive with a carboxyl group.
• engineering plastics highly heat-resistant engineering plastics and super engineering plastics
• shear-mix and dissolve molten resin such as engineering plastic with a high-pressure supercritical fluid, followed by foam injection molding.
• the objective of the present invention is to provide thermally expandable microcapsules that have excellent heat resistance at high temperatures, high foaming performance even at high temperatures, and excellent moldability, without requiring special molding machines even when using engineering plastics, etc.
• the present disclosure (4) is a thermally expandable microcapsule in any combination with any of the present disclosures (1) to (3), wherein the polymer contains 45% by weight or more and 65% by weight or less of structural units derived from a nitrile monomer (I) and 35% by weight or more and 55% by weight or less of structural units derived from a carboxyl group-containing monomer (II), and the nitrile monomer (I) includes acrylonitrile.
• the difference is preferably 0.5% or more, more preferably 1.0% or more.
• the Tg % (Ts+20° C.) is preferably 0% or more, and is preferably 5% or less, and more preferably 3% or less.
• the Tg% refers to the rate of change in sample weight and can be measured using a thermogravimetric/differential thermal analyzer (TG/DTA). Specifically, for example, 20 ⁇ g of sample is placed in an aluminum container with a diameter of 5 mm and a depth of 2 mm, heated from 40° C. to 350° C.
• the Tg% at the foaming initiation temperature Ts obtained from the TMA measurement results and the Tg% at the foaming initiation temperature Ts + 20° C. are measured, and the difference therebetween can be calculated.
• the difference between the Tg% at Ts and the Tg% at Ts + 20° C. is considered to correspond to a change in state, such as the weight of gas outflowing from the foaming initiation temperature to a high-temperature range.
• the thermally expandable microcapsules of the present invention preferably have a true density of 1.08 g/ cm3 or more at the lower limit and 1.50 g/ cm3 at the upper limit.
• a true density can be measured using a true density meter (Ultrapyc 5000, manufactured by Anton Parr, etc.) under conditions of a pressure of 12 psi, a temperature of 25° C., and a gas type of helium.
• the content of the acrylonitrile-derived structural units in the polymer is preferably 23% by weight or more, more preferably 26% by weight or more, and is preferably 43% by weight or less, more preferably 37% by weight or less.
• the content of the structural units derived from methacrylonitrile in the polymer is preferably 15% by weight or more, more preferably 20% by weight or more, and is preferably 31% by weight or less, more preferably 28% by weight or less.
• the polymerizable monomer may be a monomer having two or more radically polymerizable double bonds, and specific examples thereof include divinylbenzene, di(meth)acrylate, tri- or higher functional (meth)acrylate, and the like.
• examples of the di(meth)acrylate include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, etc.
• the metal cation is not particularly limited as long as it reacts with the carboxyl group of the copolymer to ionically crosslink the copolymer, and examples thereof include ions of Li, Na, K, Zn, Mg, Ca, Ba, Sr, Mn, Al, Ti, Ru, Fe, Ni, Cu, Cs, Sn, Cr, and Pb. These may be used alone or in combination of two or more. Among these, Ca, Zn, and Al ions are preferred, and Zn ions are particularly preferred. Although the combination of two or more of the above metal cations is not particularly limited, it is preferable to use an alkali metal ion in combination with a metal cation other than the alkali metal ion.
• the presence of the alkali metal ion activates functional groups such as carboxyl groups, thereby promoting the reaction between the metal cation other than the alkali metal and the carboxyl group of the copolymer.
• the alkali metal include Na, K, and Li.
• the Si-based compound and Mg-based compound preferably contain oxides, hydroxides, carbonates or hydrogen carbonates of silicon and magnesium. These Si-based compounds and Mg-based compounds may be used alone or in combination of two or more.
• Examples of the Si-based compound include colloidal silica, silicate sol, No. 3 water glass, sodium orthosilicate, sodium metasilicate, etc. Among these, colloidal silica is preferred.
• Examples of the Mg-based compound include magnesium oxide, magnesium hydroxide, magnesium hydroxide, hydrotalcite, dihydrotalcite, magnesium carbonate, basic magnesium carbonate, magnesium calcium carbonate, magnesium phosphate, magnesium hydrogen phosphate, magnesium pyrophosphate, magnesium borate, etc. Of these, magnesium hydroxide is preferred.
• the shell may further contain stabilizers, UV absorbers, antioxidants, antistatic agents, flame retardants, silane coupling agents, colorants, etc. as needed.
• a volatile expanding agent is encapsulated as a core agent in the shell.
• the volatile expanding agent is a substance that becomes gaseous at a temperature below the softening point of the polymer that constitutes the shell, and is preferably a low-boiling organic solvent.
• volatile expanding agent examples include low molecular weight hydrocarbons such as ethane, ethylene, propane, propene, n-butane, isobutane, butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, petroleum ether, isooctane, octane, decane, isododecane, dodecane, and hexanedecane.
• low molecular weight hydrocarbons such as ethane, ethylene, propane, propene, n-butane, isobutane, butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, petroleum ether, isooctane, octane, decane, isododecane, dodecan
• chlorofluorocarbons such as CCl3F , CCl2F2 , CClF3 , and CClF2 - CClF2 ; and tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane.
• chlorofluorocarbons such as CCl3F , CCl2F2 , CClF3 , and CClF2 - CClF2
• tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane.
• the use of high-boiling hydrocarbons having 8 or more carbon atoms can improve the maximum expansion temperature, and the use of low-boiling hydrocarbons having 5 or less carbon atoms can increase the expansion ratio and allow expansion to begin quickly.
• a thermally decomposable compound that is thermally decomposed into a gaseous form when heated may be used as the volatile expanding agent.
• the method for producing the thermally expandable microcapsules which are one embodiment of the present invention, is not particularly limited, but they can be produced, for example, by carrying out the steps of preparing an aqueous dispersion medium, dispersing an oily mixture containing a monomer composition, a volatile expanding agent, a metal cation salt, etc. in the aqueous dispersion medium, and polymerizing the monomer composition.
• the monomer composition may contain the nitrile monomer (I), the carboxyl group-containing monomer (II), and other monomers.
• the first step is to prepare an aqueous dispersion medium.
• an aqueous dispersion medium containing silicon dioxide is prepared by adding water and a dispersion stabilizer containing silicon dioxide, and optionally a co-stabilizer, to a polymerization reaction vessel.
• alkali metal nitrite, stannous chloride, stannic chloride, potassium dichromate, etc. may also be added as needed.
• the dispersion stabilizer containing silicon dioxide includes colloidal silica.
• the colloidal silica may be alkaline colloidal silica having a colloidal solution (aqueous dispersion) with a pH of more than 7, or acidic colloidal silica having a pH of less than 7. Of these, alkaline colloidal silica is more preferred.
• the colloidal silica preferably contains 10 to 50% by weight of silicon dioxide as a solid content and is monodisperse.
• the amount of the silicon dioxide-containing dispersion stabilizer added is determined appropriately depending on the particle size of the thermally expandable microcapsules, but the preferred lower limit is 2.5 parts by weight and the preferred upper limit is 7 parts by weight per 100 parts by weight of the oily mixture (oil phase). The more preferred lower limit is 3 parts by weight and the even more preferred upper limit is 5 parts by weight.
• the amount of oil phase refers to the total amount of the monomer and volatile expanding agent.
• auxiliary stabilizers examples include condensation products of diethanolamine and aliphatic dicarboxylic acids, and condensation products of urea and formaldehyde.
• Other examples include polyvinylpyrrolidone, polyethylene oxide, polyethyleneimine, tetramethylammonium hydroxide, gelatin, methylcellulose, polyvinyl alcohol, dioctyl sulfosuccinate, sorbitan esters, and various emulsifiers.
• the oily mixture and the aqueous dispersion medium may be prepared in separate containers, and the oily mixture may be dispersed in the aqueous dispersion medium by stirring in a separate container, and then added to the polymerization reaction vessel.
• an inorganic compound is present at the interface between the oil droplets of the oily mixture and the aqueous dispersion medium, and as a result, the inorganic compound can be present on the surface of the resulting thermally expandable microcapsules.
• a polymerization initiator is used to polymerize the monomers. The polymerization initiator may be added to the oily mixture in advance, or may be added after the aqueous dispersion medium and the oily mixture are stirred and mixed in a polymerization reaction vessel.
• Examples of a method for emulsifying and dispersing the oily mixture in an aqueous dispersion medium to a predetermined particle size include a method of stirring with a homomixer (for example, manufactured by Tokushu Kika Kogyo Co., Ltd.) or a method of passing the mixture through a static dispersion device such as a line mixer or an element-type static disperser.
• a homomixer for example, manufactured by Tokushu Kika Kogyo Co., Ltd.
• a static dispersion device such as a line mixer or an element-type static disperser.
• the aqueous dispersion medium and the polymerizable mixture may be supplied separately to the static dispersing device, or a dispersion liquid that has been mixed and stirred in advance may be supplied.
• the thermally expandable microcapsules which are one embodiment of the present invention, can be produced by subjecting the dispersion obtained through the above-mentioned steps to a process of polymerizing the monomer by heating, a process of washing, and a process of drying.
• the polymerization temperature is preferably 50° C. or higher and 60° C. or lower.
• the polymerization time is preferably 4 hours or longer and 24 hours or shorter.
• the polymerization pressure is preferably 0.1 MPa or higher and 1 MPa or lower.
• Masterbatch pellets can be obtained by mixing the thermally expandable microcapsules of the present invention with a resin (base resin).
• a foamable resin composition can be obtained by adding a matrix resin such as a thermoplastic resin to the thermally expandable microcapsules of the present invention.
• An ink containing the thermally expandable microcapsules and resin can also be used as a foamable ink.
• Compositions containing the thermally expandable microcapsules and resin of the present invention are preferably used for applications such as adhesives, rubber chips, foam chips, flooring materials, rock consolidation materials, paints, coating materials, reinforcing fibers, composite materials, electronic components, and molding materials.
• the molding materials are preferably used for molding by injection molding, extrusion molding, blow molding, rotational molding, vacuum molding, inflation molding, calendar molding, slush molding, dip molding, foam molding, fused deposition modeling, inkjet printing, stereolithography, and laser sintering.
• the curable resin examples include epoxy resin, (meth)acrylic resin, urethane resin, phenol resin, cyanate resin, isocyanate resin, maleimide resin, benzoxazine resin, silicone resin, fluororesin, polyimide resin, and phenoxy resin.
• the curable resin preferably includes an epoxy resin. These curable resins may be used alone or in combination of two or more.
• the content of the thermally expandable microcapsules in the masterbatch pellets is not particularly limited, but a preferred lower limit is 10 parts by weight and a preferred upper limit is 90 parts by weight per 100 parts by weight of the thermoplastic resin.
• the method for producing the masterbatch pellets is not particularly limited, but examples include a method in which raw materials such as a base resin and various additives are pre-kneaded using a co-rotating twin-screw extruder or the like. The mixture is then heated to a predetermined temperature, a blowing agent such as thermally expandable microcapsules is added, and the resulting mixture is further kneaded. The resulting mixture is then cut into pellets of a desired size using a pelletizer to form the masterbatch.
• a pellet-shaped masterbatch may be produced by kneading raw materials such as the base resin and thermally expandable microcapsules using a batch kneader and then granulating them using a granulator.
• the kneading machine is not particularly limited as long as it can knead the thermally expandable microcapsules without destroying them, and examples thereof include a pressure kneader and a Banbury mixer.
• the molding method for the foamed molded article is not particularly limited, and examples include kneading molding, calendar molding, extrusion molding, and injection molding.
• injection molding the process is not particularly limited, and examples include the short shot method, in which a portion of the resin material is placed in a mold and foamed, and the core-back method, in which the mold is fully filled with the resin material and then opened to the desired extent for foaming.
• aqueous dispersion medium was prepared by adding 8 L of water, 5 parts by weight of colloidal silica as a dispersant, and 0.3 parts by weight of polyvinylpyrrolidone to a polymerization reaction vessel.
• An oily mixture consisting of the monomers and metal cation salts in the amounts shown in Tables 1 and 2 was then added to the aqueous dispersion medium and suspended to prepare a dispersion.
• the resulting dispersion was stirred and mixed using a homogenizer and placed in a nitrogen-purged pressure polymerization vessel.
• the reaction was carried out at the polymerization pressure shown in Tables 1 and 2, at the polymerization temperature and for the polymerization time shown in Tables 1 and 2, to obtain a reaction product.
• the resulting reaction product was repeatedly filtered and washed with water, and then dried to obtain thermally expandable microcapsules.
• Tg% Measurement The weight change rate (Tg%) of the thermally expandable microcapsules was measured using a thermogravimetric/differential thermal analyzer (TG/DTA) (TG/DTA6200 (manufactured by Hitachi, Ltd.)). Specifically, 20 ⁇ g of the sample was placed in an aluminum container with a diameter of 5 mm and a depth of 2 mm, heated from 40°C to 350°C at a heating rate of 5°C/min, the change in the weight of the sample was measured, and the difference between the Tg% at the foaming onset temperature Ts obtained from the TMA measurement results and the Tg% at the foaming onset temperature Ts + 20°C was calculated.
• TG/DTA thermogravimetric/differential thermal analyzer
• Apparatus Gel permeation chromatograph GPC (manufactured by JASCO) Detector: Differential refractive index detector RI (JASCO RI-4030) Column: Shodex LF-804 (two columns connected) Flow rate: 0.8 mL/min Column temperature: 40°C ⁇ Injection volume: 0.200mL Standard sample: Monodisperse polystyrene manufactured by Tosoh Corporation
• the density of the resulting foamed molded article was measured in accordance with JIS K 7112 Method A (underwater displacement method).
• the specific gravity is an index of heat resistance, which is the objective of the present invention. If the heat resistance is poor, the specific gravity will be high because the microcapsules will shrink after expanding at high temperatures. Therefore, if a foamed molded product with a low specific gravity is obtained, the thermally expandable microcapsules can be said to have excellent heat resistance.
• the present invention makes it possible to provide thermally expandable microcapsules that have excellent heat resistance at high temperatures, high foaming performance even at high temperatures, and excellent moldability, without the need for special molding machines, even when using engineering plastics, etc.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
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• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Dispersion Chemistry (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

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Citations (4)

• 2025
  • 2025-01-31 JP JP2025528499A patent/JP7767688B1/ja active Active
  • 2025-01-31 WO PCT/JP2025/003155 patent/WO2025169847A1/ja active Pending
  • 2025-02-04 TW TW114103968A patent/TW202600772A/zh unknown

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