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  • 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
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  • 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
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  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/16—Making expandable particles
  • C08J9/20—Making expandable particles by suspension polymerisation in the presence of the blowing agent
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • 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
  • B01J13/18—In situ polymerisation with all reactants being present in the same phase
  • B01J13/185—In situ polymerisation with all reactants being present in the same phase in an organic phase
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  • C08F2/00—Processes of polymerisation
  • C08F2/12—Polymerisation in non-solvents
  • C08F2/16—Aqueous medium
  • C08F2/18—Suspension polymerisation
  • C08F2/20—Suspension polymerisation with the aid of macromolecular dispersing agents
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  • C08F2/00—Processes of polymerisation
  • C08F2/44—Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers
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  • 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
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  • 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
  • C08F220/10—Esters
  • C08F220/12—Esters of monohydric alcohols or phenols
  • C08F220/14—Methyl esters, e.g. methyl (meth)acrylate
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  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0066—Use of inorganic compounding ingredients
  • C08J9/0071—Nanosized fillers, i.e. having at least one dimension below 100 nanometers
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  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
  • C08J9/08—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent developing carbon dioxide
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  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
  • C08J9/14—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent organic
  • C08J9/141—Hydrocarbons
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  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/22—After-treatment of expandable particles; Forming foamed products
  • C08J9/228—Forming foamed products
  • C08J9/236—Forming foamed products using binding agents
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  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
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  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/04—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
  • C08L27/06—Homopolymers or copolymers of vinyl chloride
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  • C08L33/00—Compositions of homopolymers or 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 of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/18—Homopolymers or copolymers of nitriles
  • C08L33/22—Homopolymers or copolymers of nitriles containing four or more carbon atoms
• • C—CHEMISTRY; METALLURGY
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  • C08J2203/00—Foams characterized by the expanding agent
  • C08J2203/02—CO2-releasing, e.g. NaHCO3 and citric acid
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  • C08J2203/00—Foams characterized by the expanding agent
  • C08J2203/14—Saturated hydrocarbons, e.g. butane; Unspecified hydrocarbons
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  • C08J2203/00—Foams characterized by the expanding agent
  • C08J2203/22—Expandable microspheres, e.g. Expancel®
• • C—CHEMISTRY; METALLURGY
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  • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2327/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
  • C08J2327/06—Homopolymers or copolymers of vinyl chloride
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  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/24—Acids; Salts thereof
  • C08K3/26—Carbonates; Bicarbonates
  • C08K2003/265—Calcium, strontium or barium carbonate
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  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/10—Esters; Ether-esters
  • C08K5/12—Esters; Ether-esters of cyclic polycarboxylic acids
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  • C08L2203/00—Applications
  • C08L2203/14—Applications used for foams
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  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/14—Polymer mixtures characterised by other features containing polymeric additives characterised by shape
  • C08L2205/18—Spheres
  • C08L2205/20—Hollow spheres

Definitions

• the present invention relates to thermally expandable microcapsules, and foaming resin compositions and foams using the thermally expandable microcapsules.
• foaming agents have been used to foam materials for the purpose of reducing the weight and increasing the functionality of resin materials.
• foaming agents thermally expandable microcapsules and chemical foaming agents are generally used.
• Thermally expandable microcapsules are widely known in which a liquid volatile expanding agent that becomes gaseous at a temperature below the softening point of the shell polymer is encapsulated in a thermoplastic shell polymer.
• Patent Document 1 discloses a method for producing thermally expandable microcapsules encapsulating a volatile expanding agent by adding, while stirring, an oil mixture obtained by mixing a volatile expanding agent such as a low-boiling aliphatic hydrocarbon with a monomer into an aqueous dispersion medium containing a dispersant together with an oil-soluble polymerization catalyst, and carrying out suspension polymerization.
• An object of the present invention is to provide a thermally expandable microcapsule that enables the production of a molded article having a high expansion ratio, light weight and excellent appearance, and a foaming resin composition and foam using the thermally expandable microcapsule.
• the present disclosure (1) is a thermally expandable microcapsule in which a shell made of a polymer contains a volatile expanding agent as a core agent, wherein the shell is a thermally expandable microcapsule containing a polymer obtained by polymerizing a monomer composition containing a carbonyl group-containing monomer, and silicon dioxide, and having a volatile content of 0.55% by weight or more and 2% by weight or less when left standing at a temperature of 70 ° C. for 1 hour.
• the present disclosure (2) is the thermally expandable microcapsule according to the present disclosure (1), which has a volatile content of 20% by weight or more and 30% by weight or less when left standing at a temperature of 210° C. for 20 minutes.
• the present disclosure (3) is the thermally expandable microcapsule according to (1) or (2), wherein the ratio of the volatile matter when left standing at a temperature of 70 ° C. for 1 hour to the volatile matter when standing at a temperature of 210 ° C. for 20 minutes is 8% or less.
• the present disclosure (4) is a thermally expandable microcapsule according to any one of the present disclosure (1) to (3), which has a weight increase rate of 60% by weight or less when left standing for 12 hours at a temperature of 50 ° C. and a humidity of 80% or more.
• the present disclosure (5) is the thermally expandable microcapsule according to any one of the present disclosure (1) to (4), having an average particle size of 10 ⁇ m or more and 45 ⁇ m or less.
• the present disclosure (6) is the thermally expandable microcapsule according to any one of the present disclosure (1) to (5), which has a maximum foaming temperature (Tmax) of 180°C or higher and 225°C or lower.
• Tmax maximum foaming temperature
• (7) of the present disclosure is a foamable resin composition containing the thermally expandable microcapsules according to any one of (1) to (6) of the present disclosure and a thermoplastic resin.
• the present disclosure (8) is a foam obtained using the foamable resin composition according to the present disclosure (7). The present invention will be described in detail below.
• thermally expandable microcapsules having a high expansion ratio and capable of producing a lightweight molded article having excellent appearance can be obtained by controlling the volatile content of a polymer obtained by polymerizing a monomer composition containing a carbonyl group-containing monomer in the shell and thermally expandable microcapsules containing silicon dioxide, thereby completing the present invention.
• the thermally expandable microcapsules of the present invention have a volatile content of 0.55% by weight or more and 2% by weight or less when allowed to stand at a temperature of 70° C. for 1 hour.
• the volatile matter content is 0.55% by weight or more, both the appearance of the molded article and the improvement of foamability can be achieved.
• the content is 2% by weight or less, it is possible to particularly improve the appearance of the molded product.
• such thermally expandable microcapsules are unlikely to aggregate during foaming, and can contribute to the improvement of foaming performance.
• thermally expandable microcapsules are excellent in fluidity when aggregated into multiparticles, they can be stably charged from a hopper or the like at the time of molding, for example.
• the preferred lower limit of the volatile content after standing at the temperature of 70° C. for 1 hour is 0.57% by weight, the more preferred lower limit is 0.6% by weight, the preferred upper limit is 1.8% by weight, and the more preferred upper limit is 1.5% by weight.
• the volatile content after standing at a temperature of 70° C. for 1 hour can be measured from the change in weight after heating for 1 hour at a temperature of 70° C. and a humidity of less than 20% using an oven. In the volatile content measurement, when the humidity is less than 20%, the difference in weight change due to the difference in humidity is negligible.
• the volatile content when left standing at a temperature of 70 ° C. for 1 hour the volatile content, the volatile content ratio, the weight increase rate, and the average circularity after standing at a temperature of 210 ° C. for 20 minutes, which will be described later, can be controlled.
• the thermally expandable microcapsules of the present invention preferably have a volatile content of 20% by weight or more and 30% by weight or less when allowed to stand at a temperature of 210° C. for 20 minutes. Sufficient foamability can be ensured because the volatile content is 20% by weight or more. In addition, when the amount is 30% by weight or less, it is possible to secure a high appearance when the foamed molded article is formed.
• a more preferable lower limit of the volatile content when left standing at the temperature of 210° C. for 20 minutes is 23% by weight, a more preferable lower limit is 25% by weight, a more preferable upper limit is 28% by weight, and a further preferable upper limit is 27% by weight.
• the volatile content when left standing at a temperature of 210° C. for 20 minutes can be measured from the change in weight after heating for 20 minutes at a temperature of 210° C. and a humidity of less than 20% using an oven.
• the ratio of the volatile matter after standing at a temperature of 70°C for 1 hour to the volatile matter when standing at a temperature of 210°C for 20 minutes is preferably 8% or less.
• the above ratio is 8% or less, it is possible to suppress aggregation after foaming and obtain a foamed molded product with a good (smooth) appearance and a high foaming ratio.
• a more preferred upper limit is 7.5%, a still more preferred upper limit is 5%, and a still more preferred upper limit is 3%.
• the preferable lower limit is not particularly limited, it is 0%.
• the heat-expandable microcapsules of the present invention preferably have a weight increase rate of 60% by weight or less when allowed to stand at a temperature of 50° C. and a humidity of 80% or more for 12 hours.
• the weight increase rate is 60% by weight or less, it is possible to improve the appearance of a foamed molded article.
• a more preferable upper limit of the weight increase rate is 50% by weight, a more preferable upper limit is 35% by weight, a preferable lower limit is 10% by weight, and a more preferable lower limit is 20% by weight.
• the weight increase rate can be measured from the change in weight when left standing for 12 hours at a temperature of 50° C. and a humidity of 80% or higher using a thermo-hygrostat. In the measurement of the weight increase rate, when the humidity is 80% or more, the difference in weight change due to the difference in humidity is negligible.
• the thermally expandable microcapsules of the present invention preferably have a maximum foaming temperature (Tmax) with a lower limit of 180°C and a preferred upper limit of 225°C.
• Tmax maximum foaming temperature
• the heat resistance is improved, and when the composition containing the thermally expandable microcapsules is molded in a high temperature region, the thermally expandable microcapsules can be prevented from bursting and shrinking.
• the cohesion of the thermally expandable microcapsules during molding can be suppressed, and the appearance can be improved.
• a more preferable lower limit is 185°C
• a further preferable lower limit is 190°C
• a more preferable upper limit is 222°C
• a further preferable upper limit is 220°C.
• the maximum foaming temperature means the temperature at which the diameter of the thermally expandable microcapsules reaches its maximum (maximum displacement) when the diameter of the thermally expandable microcapsules is measured while being heated from room temperature. Also, the temperature at which the displacement starts to rise is defined as the foaming start temperature.
• the preferable upper limit of foaming start temperature is 170 degreeC.
• Ts foaming start temperature
• a more preferred upper limit is 165°C
• a preferred lower limit is 145°C
• a more preferred upper limit is 165°C.
• the maximum displacement (Dmax) measured by thermomechanical analysis has a preferred lower limit of 350 ⁇ m, a preferred upper limit of 1600 ⁇ m, a more preferred lower limit of 500 ⁇ m, and a more preferred upper limit of 1500 ⁇ m. Within the above range, the foaming ratio is improved and desired foaming performance can be obtained.
• the maximum amount of displacement is the value at which the diameter of the entire predetermined amount of thermally expandable microcapsules becomes maximum when the diameter is measured while heating a predetermined amount of thermally expandable microcapsules from room temperature.
• the preferred lower limit of the average particle size (volume average particle size) of the thermally expandable microcapsules of the present invention is 10 ⁇ m, and the preferred upper limit thereof is 45 ⁇ m.
• the content is within the above range, the obtained molded article has moderate cells, a sufficient expansion ratio can be obtained, and an excellent appearance can be obtained.
• a more preferable lower limit is 15 ⁇ m, a more preferable lower limit is 20 ⁇ m, a more preferable upper limit is 35 ⁇ m, a still more preferable upper limit is 32 ⁇ m, and a particularly preferable upper limit is 30 ⁇ m.
• the CV value of the volume average particle diameter of the thermally expandable microcapsules of the present invention is preferably 35% or less, usually 10% or more, preferably 15% or more.
• the average particle size (volume average particle size) and CV value can be measured by using a particle size distribution analyzer or the like.
• the preferred lower limit of the average circularity of the thermally expandable microcapsules of the present invention is 0.910, and the preferred upper limit thereof is 0.980.
• the thickness within the above range, the appearance at the time of molding can be made smooth without dents.
• a more preferable lower limit is 0.920, and a more preferable upper limit is 0.970.
• the above-mentioned average circularity is obtained by measuring the circularity from images during wet measurement with Mastersizer 3000 (manufactured by Malvern Panalytical), for example, and calculating the average circularity.
• the circularity is a numerical value obtained by dividing the area calculated from the image of the thermally expandable microcapsule by the area of the circumscribed circle of the image of the thermally expandable microcapsule (image area of the thermally expandable microcapsule/area of the circumscribed circle of the image of the thermally expandable microcapsule).
• the average circularity may be calculated by measuring the circularity using a dry measurement image of CALPAS (Nippon Laser Co., Ltd.).
• the shell constituting the thermally expandable microcapsule of the present invention contains a polymer obtained by polymerizing a monomer composition containing a carbonyl group-containing monomer, and silicon dioxide.
• the shell includes silicon dioxide.
• the silicon dioxide may adhere to the surface of the shell, or may be mixed in the shell.
• Silicon dioxide also includes hydrates of silicon dioxide. Examples of the silicon dioxide include those contained in fine silica particles and those contained in colloidal silica.
• the colloidal silica is a colloid of silicon dioxide or a hydrate of silicon dioxide.
• the colloidal silica containing silicon dioxide preferably has an average particle size of 10 to 300 nm.
• a preferable lower limit of the silicon dioxide content in the thermally expandable microcapsules of the present invention is 1% by weight, and a preferable upper limit thereof is 5% by weight.
• the average particle size of the thermally expandable microcapsules can be stably maintained, and by setting the silicon dioxide content to 5% by weight or less, it is possible to obtain thermally expandable microcapsules having excellent foaming performance.
• a more preferable lower limit of the content of silicon dioxide is 1.5% by weight, a more preferable upper limit is 3% by weight, a still more preferable lower limit is 1.7% by weight, and a further preferable upper limit is 2.8% by weight.
• the shell contains a polymer obtained by polymerizing a monomer composition containing a carbonyl group-containing monomer, and silicon dioxide.
• Examples of the carbonyl group-containing monomer include radically polymerizable unsaturated carboxylic acid monomers having 3 to 8 carbon atoms, radically polymerizable unsaturated carboxylic acid ester monomers having 3 to 8 carbon atoms, polyfunctional carboxylic acid ester monomers, and the like.
• the radically polymerizable unsaturated carboxylic acid monomer having 3 to 8 carbon atoms for example, one having one free carboxyl group for ionic cross-linking per molecule can be used.
• Specific examples include unsaturated carboxylic acids and anhydrides thereof, and these may be used alone or in combination of two or more.
• the unsaturated carboxylic acid include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid and cinnamic acid, and unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, citraconic acid and chloromaleic acid.
• acrylic acid, methacrylic acid, maleic acid, maleic anhydride, and itaconic acid are particularly preferred.
• a preferable lower limit of the content of the radically polymerizable unsaturated carboxylic acid monomer having 3 to 8 carbon atoms in the monomer composition is 5% by weight, and a preferable upper limit thereof is 50% by weight. By making it 5% by weight or more, the maximum foaming temperature can be raised, and by making it 50% by weight or less, it is possible to improve the expansion ratio.
• a preferred lower limit is 10% by weight and a preferred upper limit is 30% by weight.
• Examples of the radical polymerizable unsaturated carboxylic acid ester monomer having 3 to 8 carbon atoms are preferably (meth)acrylic acid esters, and particularly preferred are methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate and n-butyl methacrylate. Alicyclic/aromatic/heterocyclic ring-containing methacrylic acid esters such as cyclohexyl methacrylate, benzyl methacrylate and isobornyl methacrylate are also preferred.
• a preferable lower limit of the content of the radically polymerizable unsaturated carboxylic acid ester monomer having 3 to 8 carbon atoms in the monomer composition is 0.01% by weight, and a preferable upper limit thereof is 35% by weight.
• a preferable upper limit thereof is 35% by weight.
• the polyfunctional carboxylic acid ester monomer refers to a carboxylic acid ester monomer having two or more radically polymerizable double bonds, and is different from the radically polymerizable unsaturated carboxylic acid ester monomer having 3 to 8 carbon atoms.
• the polyfunctional carboxylic acid ester monomer has a role as a cross-linking agent. By containing the polyfunctional carboxylic acid ester monomer, the strength of the shell can be enhanced, and the cell walls are less likely to break during thermal expansion.
• polyfunctional carboxylic acid ester monomers include di(meth)acrylates and tri- or higher functional (meth)acrylates.
• di(meth)acrylate examples 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 and the like.
• 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, trimethylolpropane di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate and the like are included.
• a di(meth)acrylate of polyethylene glycol having a weight average molecular weight of 200 to 600 may be used.
• trifunctional (meth)acrylate examples include trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and triallylformal tri(meth)acrylate. Moreover, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. are mentioned as said tetra- or more functional (meth)acrylate. Among these, a trifunctional one such as trimethylolpropane tri(meth)acrylate and a bifunctional (meth)acrylate such as polyethylene glycol are relatively uniformly crosslinked to the acrylonitrile-based shell.
• a preferable lower limit of the content of the polyfunctional carboxylic acid ester monomer in the monomer composition is 0.1% by weight, and a preferable upper limit thereof is 1.0% by weight.
• a preferable lower limit of the content of the polyfunctional carboxylic acid ester monomer in the monomer composition is 0.1% by weight, and a preferable upper limit thereof is 1.0% by weight.
• the monomer composition preferably contains a nitrile-based monomer such as acrylonitrile and methacrylonitrile in addition to the carbonyl group-containing monomer.
• a nitrile-based monomer such as acrylonitrile and methacrylonitrile
• the gas barrier properties of the shell can be improved.
• vinylidene chloride, divinylbenzene, vinyl acetate, styrene-based monomers, and the like may also be contained.
• the preferable lower limit of the nitrile-based monomer content in the monomer composition is 40% by weight, and the preferable upper limit is 90% by weight.
• the gas barrier property of the shell can be enhanced and the expansion ratio can be improved.
• heat resistance can be improved and yellowing can be prevented.
• a more preferable lower limit is 50% by weight, and a more preferable upper limit is 80% by weight.
• the monomer composition preferably contains 40 to 90% by weight of nitrile monomer and 10 to 60% by weight of carbonyl group-containing monomer.
• the monomer composition contains a polymerization initiator for polymerizing the monomers.
• a polymerization initiator for example, dialkyl peroxide, diacyl peroxide, peroxyester, peroxydicarbonate, azo compound and the like are preferably used. Specific examples include dialkyl peroxides such as methyl ethyl peroxide, di-t-butyl peroxide and dicumyl peroxide; diacyl peroxides such as isobutyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide and 3,5,5-trimethylhexanoyl peroxide.
• t-butyl peroxypivalate t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate and the like can be mentioned.
• Peroxy esters such as cumyl peroxyneodecanoate, ( ⁇ , ⁇ -bis-neodecanoylperoxy) diisopropylbenzene; bis(4-t-butylcyclohexyl) peroxydicarbonate, di-n-propyl-oxydicarbonate, diisopropyl peroxydicarbonate and the like.
• peroxydicarbonates such as di(2-ethylethylperoxy)dicarbonate, dimethoxybutylperoxydicarbonate, and di(3-methyl-3-methoxybutylperoxy)dicarbonate are included.
• azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(1-cyclohexanecarbonitrile), and the like.
• a preferable lower limit of the weight average molecular weight of the polymer constituting the shell is 100,000, and a preferable upper limit thereof is 2,000,000.
• a decrease in shell strength can be suppressed, and when it is 2,000,000 or less, an excessive increase in shell strength can be suppressed, and a decrease in expansion ratio can be suppressed.
• the shell may further contain a stabilizer, an ultraviolet absorber, an antioxidant, an antistatic agent, a flame retardant, a silane coupling agent, a coloring agent, and the like, if necessary.
• the thermally expandable microcapsules of the present invention contain a volatile expanding agent as a core agent in the shell.
• the volatile expansion 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 point organic solvent.
• volatile swelling 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 CCl 3 F, CCl 2 F 2 , CClF 3 and CClF 2 -CClF 2 ; and tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane and trimethyl-n-propylsilane.
• tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane and trimethyl-n-propylsilane.
• isobutane, n-butane, n-pentane, isopentane, n-hexane, isooctane, isododecane and mixtures thereof are preferred.
• These volatile swelling agents may be used alone or in combination of two or more.
• a thermally decomposable compound that is thermally decomposed by heating into
• thermoly expandable microcapsules of the present invention it is preferable to use a low-boiling hydrocarbon having 5 or less carbon atoms among the above-mentioned volatile expanding agents.
• a hydrocarbon having 5 or less carbon atoms
• thermally expandable microcapsules that have a high foaming ratio and start foaming quickly.
• a thermally decomposable compound that is thermally decomposed by heating into a gaseous state may be used.
• the method for producing the thermally expandable microcapsules of the present invention is not particularly limited.
• the microcapsules can be produced by the steps of preparing an aqueous medium, dispersing an oil mixture containing a monomer composition and a volatile swelling agent in the aqueous medium, and polymerizing the monomers.
• the monomer composition for example, one containing 40 to 90% by weight of the nitrile monomer and 10 to 60% by weight of the carbonyl group-containing monomer can be used.
• the first step is to prepare an aqueous medium.
• an aqueous dispersion medium containing silicon dioxide is prepared by adding water, a dispersion stabilizer containing silicon dioxide, and optionally a co-stabilizer to a polymerization reactor.
• alkali metal nitrite, stannous chloride, stannic chloride, potassium dichromate, etc. may be added.
• Examples of the dispersion stabilizer containing silicon dioxide include colloidal silica.
• colloidal silica alkaline colloidal silica whose colloidal solution (aqueous dispersion) has a pH of more than 7 may be used, or acidic colloidal silica whose pH is less than 7 may be used. Among them, alkaline colloidal silica is more preferable.
• the colloidal silica preferably contains 10 to 50% by weight of silicon dioxide as a solid content and is monodispersed.
• dispersion stabilizers other than silicon dioxide examples include calcium phosphate, magnesium hydroxide, aluminum hydroxide, ferric hydroxide, barium sulfate, calcium sulfate, sodium sulfate, calcium oxalate, calcium carbonate, barium carbonate, and magnesium carbonate.
• the amount of the dispersion stabilizer containing silicon dioxide to be added is appropriately determined according to the particle size of the thermally expandable microcapsules. A more preferable lower limit is 3 parts by weight, and a more preferable upper limit is 5 parts by weight.
• the amount of the oil phase means the total amount of the monomer and the volatile swelling agent.
• co-stabilizer examples include a condensation product of diethanolamine and an aliphatic dicarboxylic acid, a condensation product of urea and formaldehyde, and the like. Also included are polyvinylpyrrolidone, polyethylene oxide, polyethyleneimine, tetramethylammonium hydroxide, gelatin, methylcellulose, polyvinyl alcohol, dioctylsulfosuccinate, sorbitan ester, and various emulsifiers.
• the combination of the dispersion stabilizer and co-stabilizer is not particularly limited, and examples thereof include a combination of colloidal silica and a condensation product, a combination of colloidal silica and a water-soluble nitrogen-containing compound, and the like. Among these, a combination of colloidal silica and a condensation product is preferred.
• the condensation product is preferably a condensation product of diethanolamine and an aliphatic dicarboxylic acid, particularly preferably a condensation product of diethanolamine and adipic acid or a condensation product of diethanolamine and itaconic acid.
• water-soluble nitrogen-containing compound examples include polydialkylaminoalkyl (meth)acrylates represented by polyvinylpyrrolidone, polyethyleneimine, polyoxyethylenealkylamine, polydimethylaminoethyl methacrylate and polydimethylaminoethyl acrylate. Also included are polydialkylaminoalkyl(meth)acrylamides represented by polydimethylaminopropylacrylamide and polydimethylaminopropylmethacrylamide, polyacrylamide, polycationic acrylamide, polyaminesulfone, polyallylamine, and the like. Among these, polyvinylpyrrolidone is preferably used.
• the amount of the condensation product or water-soluble nitrogen-containing compound is appropriately determined depending on the particle size of the thermally expandable microcapsules, but the preferred lower limit is 0.05 parts by weight and the preferred upper limit is 0.2 parts by weight with respect to 100 parts by weight of the oil mixture.
• Inorganic salts such as sodium chloride and sodium sulfate may be added in addition to the dispersion stabilizer and co-stabilizer. By adding an inorganic salt, thermally expandable microcapsules having a more uniform particle shape can be obtained.
• the amount of the inorganic salt added is preferably 0 to 100 parts by weight per 100 parts by weight of the monomer.
• the aqueous dispersion medium containing the dispersion stabilizer is prepared by blending the dispersion stabilizer and co-stabilizer with deionized water, and the pH of the aqueous phase at this time is appropriately determined depending on the type of dispersion stabilizer and co-stabilizer used.
• the pH of the aqueous phase at this time is appropriately determined depending on the type of dispersion stabilizer and co-stabilizer used.
• silicon dioxide is used as a dispersion stabilizer
• polymerization is carried out in an acidic medium, and in order to make the aqueous medium acidic, an acid such as hydrochloric acid is added as necessary to adjust the pH of the system to 3-4.
• magnesium hydroxide or calcium phosphate the polymerization is carried out in an alkaline medium.
• a step of dispersing an oily liquid mixture containing a monomer composition and a volatile expanding agent in an aqueous medium is carried out. Specifically, for example, a step of dispersing an oily mixed liquid containing a monomer composition containing 40 to 90% by weight of the nitrile-based monomer and 10 to 60% by weight of a carbonyl group-containing monomer and a volatile expanding agent in an aqueous medium.
• the monomer composition and the volatile swelling agent may be separately added to the aqueous dispersion medium to prepare an oily mixture in the aqueous dispersion medium, but usually both are mixed in advance to form an oily mixture and then added to the aqueous dispersion medium.
• an oily mixture and an aqueous dispersion medium may be prepared in advance in separate containers, and the oily mixture may be dispersed in the aqueous dispersion medium (primary dispersion) by mixing them in separate containers while stirring, and then added to the polymerization reaction vessel.
• 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 the step of dispersing an oily mixture containing the monomer composition and a volatile swelling agent in an aqueous medium include a method of stirring with a stirring blade such as a swept-back blade, a batch high-speed rotation high-shear disperser (e.g. JP-A-7-96167) and a continuous high-speed rotation high-shear disperser (e.g. JP-A-2000-191817).
• Another example is a method of passing through an in-tube type dispersing device such as a line mixer or a static in-tube mixer (static mixer).
• the step of dispersing the oil mixture containing the monomer composition and the volatile swelling agent in the aqueous medium it is preferable to disperse using a static in-tube mixer.
• a static tube mixer By using the static tube mixer, it is possible to mix in a tube instead of in a tank, and static mixing without using a stirring blade, so that the thermally expandable microcapsules of the present invention can be suitably produced.
• the static pipe mixer (static mixer) has a plurality of plate-like elements having a large number of holes formed in a tubular body having both ends opened.
• a plurality of adjacent plate-like elements are stacked so that the centers of the holes of the adjacent plate-like elements are not aligned with each other, but at least part of the mutual openings are opposed to each other.
• the thermally expandable microcapsules of the present invention can be suitably produced.
• the pressurization is preferably performed at 1 to 6 MPa.
• the pressurization can be set by the pore size and flow rate.
• the hole diameter is preferably 1 to 3 mm.
• a flow rate of 100 to 500 L/min is preferable.
• a combination such as a hole diameter of 2 mm and a flow rate of 200 L/min is suitable.
• the thermally expandable microcapsules of the present invention can be produced by heating the dispersion liquid obtained through the above-described steps to polymerize the monomers and washing the dispersion.
• the thermally expandable microcapsules produced by such a method have a high maximum foaming temperature, are excellent in heat resistance, and do not burst or shrink even during molding in a high temperature range.
• a washing step is performed.
• the cleaning process include immersion cleaning, running water cleaning, shower cleaning, and the like, and further, cleaning methods combining these with ultrasonic waves and shaking can be applied.
• the washing process can be performed in combination with the dehydration process to improve production efficiency. Specifically, the following methods are mentioned. After the slurry supplied by the dehydrator is turned into a wet cake, a predetermined amount of washing water (preferably ion-exchanged water) is supplied into the dehydrator and pressed again. Wash water is supplied and squeezed again. Repeat this process several times.
• washing water preferably ion-exchanged water
• the amount of slurry supplied to the dehydrator, the amount and ratio of washing water, and the number of times of washing are important in removing inorganic salts such as sodium chloride and sodium sulfate.
• inorganic salts such as sodium chloride and sodium sulfate.
• the amount [volume] of washing water in the washing step is preferably 2.5 to 5 times the polymerization slurry.
• a drying step is then carried out.
• the silicon dioxide content of the shell can be adjusted in addition to the purpose of volatilizing the liquid component.
• the drying step methods such as natural drying, hot air drying (fluidized bed drying), and vacuum drying can be used.
• the drying temperature is preferably 30° C. or higher, more preferably 32° C. or higher, still more preferably 35° C. or higher, preferably 70° C. or lower, more preferably 68° C. or lower, and still more preferably 65° C. or lower.
• the drying time (total drying time) in the drying step is preferably 12 hours or longer, more preferably 13 hours or longer, more preferably 14 hours or longer, preferably 20 hours or shorter, and more preferably 18 hours or shorter.
• the drying step may be performed at a constant temperature, or may be performed by changing the drying temperature stepwise. Moreover, when changing the drying temperature stepwise, it may be divided into a plurality of times. In this case, the number of drying steps is preferably 2 to 4, more preferably 3 times (first drying step to third drying step). In this case, it is preferable that the average drying temperature in the first drying step is 40°C or lower, the average drying temperature in the second drying step is higher than 40°C and lower than 50°C, and the average drying temperature in the third drying step is higher than 50°C.
• Vacuum drying is particularly preferred as the drying method.
• a method using a heating vacuum vibration dryer or the like can be used.
• the range of the vacuum value in the vacuum drying is preferably -0.065 to -0.100 MPa, more preferably -0.070 to -0.095 MPa, and even more preferably -0.075 to -0.090 MPa.
• the above vacuum value can be measured with a vacuum manometer or vacuum gauge.
• a masterbatch pellet can be obtained by mixing an expandable resin composition obtained by adding a matrix resin such as a thermoplastic resin to the thermally expandable microcapsules of the present invention, or by mixing the thermally expandable microcapsules with a base resin such as a thermoplastic resin.
• foaming can be produced by adding a foamable resin composition obtained by adding a matrix resin such as a thermoplastic resin to the masterbatch pellets, molding the mixture using a molding method such as injection molding, and then foaming the thermally expandable microcapsules by heating during molding.
• the foamable resin composition of the present invention preferably contains 0.1 to 10 parts by weight of thermally expandable microcapsules per 100 parts by weight of the matrix resin.
• the foamable resin composition may contain a chemical foaming agent.
• the chemical foaming agent is not particularly limited as long as it is in the form of a powder at room temperature, and conventionally widely used chemical foaming agents can be used.
• the chemical foaming agents are classified into organic foaming agents and inorganic foaming agents, which are further classified into thermal decomposition type and reactive type.
• ADCA azodicarbonamide
• DPT N,N'-dinitropentamethylenetetramine
• OBSH 4,4'-oxybisbenzenesulfonylhydrazide
• Inorganic pyrolytic blowing agents include hydrogen carbonates, carbonates, combinations of hydrogen carbonates and organic acid salts, and the like.
• As the chemical foaming agent it is preferable to use a thermal decomposition type chemical foaming agent.
• the decomposition temperature, the amount of gas generated, and the particle size determine the performance of the thermal decomposition type chemical blowing agent.
• the decomposition temperature of the chemical foaming agent is preferably 180 to 200°C.
• the above decomposition temperature can be adjusted by using a combination of urea-based or zinc-based foaming aids, if necessary.
• the amount of gas generated by the chemical foaming agent is preferably 220 to 240 ml/g.
• the amount of gas generated is the volume of gas generated when the chemical foaming agent decomposes. Since this gas becomes gas in the bubbles, it affects the foaming ratio.
• the bubble diameter can be reduced by using the above chemical foaming agent in combination with citrate or zinc oxide.
• the chemical foaming agent is usually powder, and the smaller the particle size, the greater the number of particles per unit weight. There is a tendency that the larger the number of particles, the larger the number of generated bubbles.
• the preferred lower limit of the average particle size (median size) of the chemical foaming agent is 4 ⁇ m, and the preferred upper limit is 20 ⁇ m. When the content is within the above range, the obtained molded article has moderate cells, a sufficient expansion ratio can be obtained, and an excellent appearance can be obtained.
• a more preferable lower limit is 5 ⁇ m, and a more preferable upper limit is 10 ⁇ m.
• the method for molding the foam molded article is not particularly limited, and examples thereof include kneading molding, calendar molding, extrusion molding, injection molding and the like.
• the method is not particularly limited, and includes a short-short method in which a part of the resin material is put into the mold and foamed, and a core-back method in which the mold is fully filled with the resin material and then opened to the desired foaming point.
• thermally expandable microcapsule that has a high expansion ratio and is capable of producing a molded product that is lightweight and has an excellent appearance, and a foaming resin composition and foam using the thermally expandable microcapsule.
• the thermally expandable microcapsules of the present invention can be suitably used for automobile members, paints, adhesives and inks.
• Example 1 (Production of thermally expandable microcapsules) 330 parts by weight of colloidal silica having a solid content of 20% by weight (average particle diameter of 20 nm), 12 parts by weight of polyvinylpyrrolidone, 1096 parts by weight of sodium chloride, and 0.85 parts by weight of sodium nitrite were added to 3300 parts by weight of ion-exchanged water and mixed, and then an aqueous dispersion medium was prepared. Alkaline colloidal silica was used as the colloidal silica (aqueous dispersion).
• an aqueous dispersion medium was charged into tank 2, and the oily mixture in tank 1 was charged into tank 2 and mixed to obtain a primary dispersion. At this time, the pH of the primary dispersion becomes 3.5 to 4.0.
• the resulting primary dispersion was passed through a static tube mixer (static mixer, manufactured by Fujikin Co., Ltd., Bunkun) at a flow rate of 200 L/min and a pressure of 1.5 MPa. The liquid that passed through was fed into the autoclave.
• the static element type disperser used had a plate-like element with a thickness of 5 mm, an effective diameter of 15 mm, a hole diameter of 2 mm, and had a punch-like shape, and had 78 holes, at least some of which could face each other between adjacent plate-like elements of different types.
• the number of units composed of the combination of the first element and the second element was set to 10 sets so that the fluid could pass through the holes of each plate-like element. Thereafter, the atmosphere was purged with nitrogen and reacted at a reaction temperature of 60° C. for 15 hours. The reaction pressure was 0.5 MPa, and the stirring was performed at 200 rpm.
• the obtained pre-dried thermally expandable microcapsules were vacuum dried (total drying time: 12.5 hours, vacuum value: -0.085 MPa) using a heating vacuum vibration dryer (manufactured by Chuo Kakoki Co., Ltd., model VU) to obtain thermally expandable microcapsules.
• a heating vacuum vibration dryer manufactured by Chuo Kakoki Co., Ltd., model VU
• first drying step was performed at set temperatures of 45, 50, and 55 ° C. for 5.5 hours (both were heated at 10 ° C./hr), and then set temperatures were 60 and 65 ° C. Drying (second drying step) was performed for 1.5 hours.
• Examples 2-6 Comparative Examples 1-6
• the obtained pre-drying thermally expandable microcapsules were dried under the drying conditions (first to third drying steps, total drying time, vacuum value) and the washing conditions (the amount of washing water per 300 L of the polymerization slurry) shown in Tables 2 and 3.
• Heat-expandable microcapsules and foam precursors were obtained in the same manner as in Example 1, except that the drying step and the washing step were performed.
• Comparative Example 7 (Production of thermally expandable microcapsules) 330 parts by weight of colloidal silica having a solid content of 20% by weight (average particle diameter of 20 nm), 12 parts by weight of polyvinylpyrrolidone, 1096 parts by weight of sodium chloride, and 0.85 parts by weight of sodium nitrite were added to 3300 parts by weight of ion-exchanged water and mixed, and then an aqueous dispersion medium was prepared. Alkaline colloidal silica was used as the colloidal silica (aqueous dispersion).
• the pH of the primary dispersion becomes 3.5 to 4.0.
• the resulting primary dispersion was passed through a static tube mixer (static mixer, manufactured by Fujikin Co., Ltd., Bunkun) at a flow rate of 200 L/min and a pressure of 1.5 MPa.
• the liquid that passed through was fed into the autoclave.
• the static element type disperser used had a plate-like element with a thickness of 5 mm, an effective diameter of 15 mm, a hole diameter of 2 mm, and had a punch-like shape, and had 78 holes, at least some of which could face each other between adjacent plate-like elements of different types.
• the number of units composed of the combination of the first element and the second element was set to 10 sets so that the fluid could pass through the holes of each plate-like element. Thereafter, the atmosphere was purged with nitrogen and reacted at a reaction temperature of 60° C. for 15 hours. The reaction pressure was 0.5 MPa, and the stirring was performed at 200 rpm. After that, 8000 L of the obtained polymerized slurry was divided and supplied to a compression dehydrator (manufactured by Ishigaki Co., Ltd., filter press), and after dehydration, a predetermined amount of washing water was supplied to the dehydrator and a washing process was performed to obtain pre-drying thermally expandable microcapsules. In the washing process, 300 L of the polymerized slurry was washed with 1000 L of washing water.
• the obtained pre-drying thermally expandable microcapsules were dried under the drying conditions (first to third drying steps, total drying time, vacuum value) and the washing conditions (the amount of washing water per 300 L of the polymerization slurry) shown in Tables 2 and 3.
• Heat-expandable microcapsules and foam precursors were obtained in the same manner as in Example 1, except that the drying step and the washing step were performed.
• thermomechanical analyzer TMA2940, manufactured by TA instruments
• Ts foaming start temperature
• Dmax maximum displacement
• Tmax maximum foaming temperature
• SiO 2 content (silicon dioxide content in the thermally expandable microcapsules) was measured using an EDS energy dispersive X-ray analyzer (JSM-6510, manufactured by JEOL Ltd.).
• thermally expandable microcapsules capable of producing molded articles having a high expansion ratio, light weight and excellent appearance, and foaming resin compositions and foams using the thermally expandable microcapsules.

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