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
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
• • 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 heat-expandable microspheres, masterbatches, compositions, and foam-molded articles.
• Heat-expandable microspheres which are fine particles with a thermoplastic resin shell and a blowing agent encapsulated inside, are characterized by expanding when heated. Furthermore, a masterbatch obtained by kneading these heat-expandable microspheres with a base resin also has the characteristic of expanding when heated.
• These heat-expandable microspheres and masterbatches are used in a wide range of applications, for example, they can be blended with a base resin and molded to produce molded articles. The heat-expandable microspheres expand upon heat treatment during molding, which not only reduces the weight of the molded articles but also provides them with decorative features, cushioning properties, etc.
• Patent Document 1 proposes such heat-expandable microspheres as heat-expandable microcapsules containing a blowing agent and having an outer shell made of a polymer composed of 15-75% by weight of a nitrile-based monomer, 10-65% by weight of a monomer having a carboxyl group, 0.1-20% by weight of a monomer having an amide group, and 0.1-20% by weight of a monomer having a cyclic structure in its side chain.
• the heat-expandable microspheres disclosed in Patent Document 1 have excellent heat and solvent resistance, and exhibit excellent foaming properties over a wide range of high temperatures, making them suitable for foam molding of thermoplastic resins and thermosetting resins at resin molding temperatures of 200°C or higher.
• a deposit known as "smear" is generated and accumulates near the discharge outlet of the molding machine, including granular base resin and expanded heat-expandable microspheres.
• the resulting smear may be mixed into the molded product or adhere to its surface, degrading the appearance of the molded product.
• an object of the present invention is to provide heat-expandable microspheres that can reduce the occurrence of resin deposits when forming foamed articles, and uses thereof.
• the present invention includes the following aspects.
• Heat-expandable microspheres comprising an outer shell containing a polymer and a blowing agent encapsulated in the outer shell and vaporized by heating, wherein the solubility parameter of the polymer is 13 (cal/cm 3 ) 1/2 or less.
• ⁇ 4> The heat-expandable microspheres according to ⁇ 2> or ⁇ 3>, wherein the polymerizable component further comprises at least one monomer selected from the group consisting of (meth)acrylic acid amide monomers and (meth)acrylic acid ester monomers.
• ⁇ 5> The heat-expandable microspheres according to ⁇ 4>, wherein the weight ratio of the at least one monomer selected from the group consisting of the (meth)acrylic acid amide monomer and the (meth)acrylic acid ester monomer in the polymerizable component is 5 to 70% by weight.
• ⁇ 6> Heat-expandable microspheres according to any one of ⁇ 2> to ⁇ 5>, wherein the weight ratio of acrylonitrile in the polymerizable component is less than 20% by weight.
• a masterbatch comprising the heat-expandable microspheres according to any one of ⁇ 1> to ⁇ 6> and a base resin, wherein the base resin has a melt flow rate of more than 60 g/10 min and a melting point of not higher than the expansion initiation temperature of the heat-expandable microspheres.
• ⁇ 8> The masterbatch according to ⁇ 7>, wherein the melting point is 60 to 130°C.
• ⁇ 9> The masterbatch according to ⁇ 7> or ⁇ 8>, wherein the content of the heat-expandable microspheres is 35 to 300 parts by weight per 100 parts by weight of the base resin.
• ⁇ 10> A composition comprising the heat-expandable microspheres according to any one of ⁇ 1> to ⁇ 6> and at least one masterbatch selected from the masterbatch according to any one of ⁇ 7> to ⁇ 9>, and a matrix component.
• ⁇ 11> A foamed molded article obtained by molding the composition according to ⁇ 10>.
• the heat-expandable microspheres of the present invention can reduce the occurrence of gum during the molding of foamed articles.
• the masterbatch of the present invention contains the above-mentioned heat-expandable microspheres, and therefore can reduce the occurrence of resin deposits during the molding of foamed articles.
• the composition of the present invention contains at least one selected from the heat-expandable microspheres and the masterbatch, and therefore can reduce the occurrence of gum during molding of a foamed article.
• the molded article of the present invention is obtained by molding the above composition, and therefore has a good appearance and is lightweight.
• the heat-expandable microspheres of the present invention comprise a polymer-containing shell and a blowing agent encapsulated in the shell that vaporizes upon heating, and the microspheres as a whole exhibit heat-expandability (the property that the entire microspheres expand upon heating).
• the heat-expandable microspheres preferably have a core-shell structure consisting of a polymer-containing shell and a core that essentially contains a blowing agent.
• the heat-expandable microspheres of the present invention are those in which the polymer forming the outer shell has a solubility parameter of 13 (cal/cm 3 ) 1/2 or less.
• the solubility parameter may be simply referred to as the SP value.
• the solubility parameter of the polymer forming the outer shell of heat-expandable microspheres is 13 (cal/cm 3 ) 1/2 or less, it is close to the solubility parameter of the matrix component, which is thought to enhance the compatibility between the heat-expandable microspheres and the matrix component, thereby making it possible to reduce the occurrence of sludge during molding.
• the solubility parameter is preferably 9.0 to 13 (cal/cm 3 ) 1/2 , more preferably 10 to 12.8 (cal/cm 3 ) 1/2 , and even more preferably 11 to 12.8 (cal/cm 3 ) 1/2 .
• the SP value is a value calculated by the Fedors method described in "POLYMER ENGINEERING AND SCIENCE, February 1974, Vol. 14, No. 2, Robert F. Fedors (pp. 147-154)".
• the SP value can be calculated from the following formula (I) using the cohesive energy (E coh ) of the atomic groups constituting the structural units of the polymer and the molar volume (V) of the atomic groups constituting the structural units.
• a structural unit derived from acrylonitrile has one secondary carbon (-CH 2 -) atomic group, one tertiary carbon (-CH ⁇ ) atomic group, and one nitrile group (-CN) atomic group.
• the structural unit derived from methacrylonitrile has one primary carbon (-CH 3 ) atomic group, one secondary carbon (-CH 2 -) atomic group, one quaternary carbon (>C ⁇ ) atomic group, and one nitrile group (-CN) atomic group.
• the above formula (II) can be generalized to the following formula (III) not only for polymers consisting of the above specific structural units but also for polymers having other structural units.
• SP value (SP 1 ⁇ a 1 +SP 2 ⁇ a 2 +...+SP n ⁇ a n )/(a 1 +a 2 +...+a n ) (III)
• SP1 is the SP value of the first structural unit in the polymer
• a1 is its weight percentage in the polymer
• SP2 to SPn are the SP values of the second to nth structural units in the polymer
• a2 to an are their weight percentages in the polymer, respectively.
• the polymer is a polymer of a polymerizable component described below
• the above a 1 to an represent the weight proportions of the respective monomers in the polymerizable component.
• the polymer forming the outer shell is preferably a polymer of a polymerizable component containing a monomer having one (radically) polymerizable carbon-carbon double bond (hereinafter, sometimes referred to as a "monomer component").
• a polymer is preferred because it allows the blowing agent to be efficiently encapsulated and provides high expansion performance.
• the weight proportion of the structural units derived from each monomer component in the polymer is the weight proportion of each monomer component in the polymerizable component.
• the polymerizable component may further contain a monomer having at least two (radically) polymerizable carbon-carbon double bonds (hereinafter, sometimes referred to as a crosslinking agent).
• the monomer component and the crosslinking agent are components capable of undergoing an addition reaction, and the crosslinking agent is a component capable of introducing a crosslinked structure into the thermoplastic resin (A).
• the weight proportion of the structural units derived from each crosslinking agent in the polymer is the weight proportion of each crosslinking agent in the polymerizable component.
• the monomer components are not particularly limited, but examples include nitrile monomers such as acrylonitrile, methacrylonitrile, fumaronitrile, and maleonitrile; vinyl halide monomers such as vinyl chloride; vinylidene halide monomers such as vinylidene chloride; vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl butyrate; unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid, as well as maleic acid, itaconic acid, fumaric acid, and cinnamic acid.
• nitrile monomers such as acrylonitrile, methacrylonitrile, fumaronitrile, and maleonitrile
• vinyl halide monomers such as vinyl chloride
• vinylidene halide monomers such as vinylidene chloride
• vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl
• Carboxyl group-containing monomers such as unsaturated dicarboxylic acids such as maleic acid and chloromaleic acid, anhydrides of unsaturated dicarboxylic acids, and unsaturated dicarboxylic acid monoesters such as monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate; methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, (meth)acrylic acid ester-based monomers such as acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate,
• carboxyl groups in the carboxyl group-containing monomer may be neutralized during or after polymerization.
• Acrylic acid and methacrylic acid may be collectively referred to as (meth)acrylic acid, and (meth)acrylate refers to acrylate or methacrylate, while (meth)acrylic refers to acrylic or methacrylic. These monomer components may be used alone or in combination.
• the polymerizable component is not particularly limited, but a carboxyl group-containing monomer is preferred as a monomer component since it improves the heat resistance of the heat-expandable microspheres and also makes it easier to adjust the solubility parameter of the polymer to fall within the above range.
• the weight ratio of the carboxyl group-containing monomer in the polymerizable component is not particularly limited, but is preferably 20 to 70 wt %, more preferably 25 to 65 wt %, and even more preferably 30 to 60 wt %.
• a weight ratio of 20 wt % or more tends to improve the heat resistance of heat-expandable microspheres.
• a weight ratio of 70 wt % or less tends to prevent the shell from becoming too rigid, improving the expandability.
• the polymerizable component contains a carboxyl group-containing monomer
• it is not particularly limited, but it is preferable to further contain at least one monomer selected from the group consisting of a (meth)acrylamide monomer and a (meth)acrylic acid ester monomer, since this improves the heat resistance of the heat-expandable microspheres.
• the weight ratio of the at least one monomer selected from the group consisting of a (meth)acrylamide monomer and a (meth)acrylic ester monomer in the polymerizable component is not particularly limited, but is preferably 5 to 70% by weight, more preferably 8 to 60% by weight, and even more preferably 8 to 50% by weight.
• a weight ratio of 5% by weight or more tends to improve the heat resistance of the heat-expandable microspheres.
• a weight ratio of 70% by weight or less tends to prevent the shell from becoming too rigid, thereby improving the expandability.
• the content of the (meth)acrylamide-based monomer or the (meth)acrylic acid ester-based monomer may be in the above weight ratio.
• the weight percentage of acrylonitrile in the polymerizable component is not particularly limited, but is preferably less than 20% by weight. Having the weight percentage of acrylonitrile in the polymerizable component within the above range is preferred in that the rigidity of the outer shell is adjusted and the expandability is improved. Also, having the weight percentage of acrylonitrile in the polymerizable component within the above range is preferred in that the solubility parameter of the polymer can be easily adjusted within the above range.
• the weight proportion of acrylonitrile in the polymerizable component is more preferably 15% by weight or less, even more preferably less than 13% by weight, and particularly preferably 10% by weight or less.
• the polymerizable component may contain methacrylonitrile.
• the polymerizable component containing methacrylonitrile is preferred in that the gas barrier properties of the outer shell are improved. Furthermore, the polymer containing methacrylonitrile is preferred in that the solubility parameter of the polymer can be easily adjusted to the above range.
• the weight ratio of methacrylonitrile in the polymerizable component is not particularly limited, but is preferably 0 to 70% by weight, more preferably 5 to 60% by weight.
• the polymerizable component may contain a crosslinking agent.
• the outer shell has a crosslinked structure, which improves the gas barrier properties and expandability.
• 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, and 1,9-nonanediol di(meth)acrylate; diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, PEG#200 di(meth)acrylate, and PEG#400 di(meth)acrylate; Polyalkylene glycol di(meth)acrylates such as acrylate, PEG #600 di(meth)acrylate, PEG #1000 di(meth)acrylate, dipropylene glycol di(me
• the weight percentage of the crosslinking agent in the polymerizable component is preferably 0 to 10% by weight, more preferably 0.1 to 5% by weight, even more preferably 0.15 to 3% by weight, particularly preferably 0.2 to 2% by weight, and most preferably 0.3 to 1.5% by weight.
• the blowing agent is a component that vaporizes when heated and is encapsulated in the outer shell of the heat-expandable microspheres, which allows the entire microsphere to exhibit thermal expandability (the property of expanding when heated).
• the blowing agent is not particularly limited, and examples thereof include hydrocarbons having 1 to 13 carbon atoms such as methane, ethane, propane, (iso)butane, (iso)pentane, (iso)hexane, (iso)heptane, (iso)octane, (iso)nonane, (iso)decane, (iso)undecane, (iso)dodecane, and (iso)tridecane; hydrocarbons having more than 13 but not more than 20 carbon atoms such as (iso)hexadecane and (iso)eicosane; and petroleum ethers such as normal paraffins and isoparaffins having an initial boiling point of 150 to 260°C
• halides of hydrocarbons having 1 to 12 carbon atoms such as methyl chloride, methylene chloride, chloroform, and carbon tetrachloride; fluorine-containing compounds such as hydrofluoroethers; silanes having an alkyl group having 1 to 5 carbon atoms such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane; and compounds that generate gas upon thermal decomposition by heating, such as azodicarbonamide, N,N'-dinitrosopentamethylenetetramine, and 4,4'-oxybis(benzenesulfonylhydrazide).
• fluorine-containing compounds such as hydrofluoroethers
• silanes having an alkyl group having 1 to 5 carbon atoms such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-prop
• the blowing agent may be composed of one compound or a mixture of two or more compounds.
• the blowing agent may be linear, branched, or cyclic, and is preferably aliphatic.
• the blowing agent preferably contains a hydrocarbon having 8 or more carbon atoms, which increases the maximum expansion temperature of the heat-expandable microspheres, and preferably contains a hydrocarbon having 6 or less carbon atoms, which increases the efficiency of the expansion of the heat-expandable microspheres.
• the content of the blowing agent in the heat-expandable microspheres of the present invention is defined as the percentage of the weight of the blowing agent encapsulated in the heat-expandable microspheres relative to the total weight of the heat-expandable microspheres.
• the content of the blowing agent is not particularly limited, but is preferably 2 to 40 wt%, more preferably 4 to 35 wt%, even more preferably 5 to 30 wt%, and particularly preferably 6 to 25 wt%.
• the blowing agent is less likely to leak to the outside during thermal expansion, and expandability tends to be improved.
• the expansion onset temperature (Ts) of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 120 to 200°C, more preferably 130 to 180°C, even more preferably 140 to 180°C, and particularly preferably 150 to 170°C.
• An expansion onset temperature of 120°C or higher tends to improve the heat resistance of the heat-expandable microspheres.
• An expansion onset temperature of 200°C or lower tends to improve the expansion performance.
• the maximum expansion temperature (Tmax) of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 155° C. or higher, more preferably 155 to 250° C., even more preferably 160 to 230° C., particularly preferably 165 to 210° C., and most preferably 170 to 200° C. Heat-expandable microspheres having a maximum expansion temperature of 155° C. or higher tend to have sufficient heat resistance.
• the expansion starting temperature (Ts) and maximum expansion temperature (Tmax) of the heat-expandable microspheres are measured by the methods described in the examples.
• the average particle size of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 1 to 200 ⁇ m, more preferably 5 to 100 ⁇ m, even more preferably 5 to 60 ⁇ m, and particularly preferably 10 to 50 ⁇ m.
• An average particle size of 1 ⁇ m or more tends to improve the expansion performance of the heat-expandable microspheres.
• An average particle size of 200 ⁇ m or less tends to improve the appearance of the resulting molded article.
• the coefficient of variation (Cv) of the particle size distribution of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 10 to 40%, more preferably 15 to 35%.
• the average particle size and particle size distribution of the heat-expandable microspheres are measured by the methods described in the Examples.
• the maximum volume expansion ratio of the heat-expandable microspheres of the present invention is not particularly limited, but is preferably 5 to 200 times, more preferably 10 to 200 times, and even more preferably 15 to 200 times. An expansion ratio of 5 times or more tends to result in a lightweight molded product. An expansion ratio of 200 times or less tends to result in a molded product with a good appearance.
• the heat-expandable microspheres of the present invention can be produced by a method including the steps of dispersing an oily mixture containing a polymerizable component, a blowing agent, and a polymerization initiator in an aqueous dispersion medium and polymerizing the polymerizable component (hereinafter sometimes referred to as the polymerization step).
• the polymerization initiator is not particularly limited, but examples thereof include peroxides and azo compounds.
• the peroxide is not particularly limited, and examples thereof 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-hex
• the azo compound is not particularly limited, and examples thereof include 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis(cyclohexane-1-carbonitrile).
• the amount of polymerization initiator used 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.
• the aqueous dispersion medium used in the polymerization step is a medium containing water, such as ion-exchanged water, as a main component for dispersing the oily mixture, and may further contain alcohols, such as methanol, ethanol, and propanol, and hydrophilic organic solvents, such as acetone.
• “hydrophilic” means a state in which the medium can be arbitrarily mixed with water.
• the amount of the aqueous dispersion medium used is not particularly limited, but is preferably 100 to 1000 parts by weight per 100 parts by weight of the polymerizable component.
• the aqueous dispersion medium may further contain an electrolyte.
• the electrolyte include sodium chloride, magnesium chloride, calcium chloride, sodium sulfate, magnesium sulfate, ammonium sulfate, sodium carbonate, etc. These electrolytes may be used alone or in combination of two or more.
• the content of the electrolyte is not particularly limited, but 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 the group consisting of water-soluble 1,1-substituted compounds having a structure in which at least one 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 at least one 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 compound selected from the group consisting of water-soluble 1,1-substituted compounds having a structure in which
• 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.
• a dispersion stabilizer examples include tricalcium phosphate, magnesium pyrophosphate obtained by a metathesis method, calcium pyrophosphate, colloidal silica, alumina sol, magnesium hydroxide, etc. 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.
• dispersion stabilization aid examples include surfactants such as polymer-type dispersion stabilization aids, cationic surfactants, anionic surfactants, zwitterionic surfactants, nonionic surfactants, etc. 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 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 gently, for example, to a degree sufficient to prevent the floating of the oil globules 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 obtained slurry is filtered using a centrifuge, pressure press, vacuum dehydrator, etc. to obtain a wet powder 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 obtained wet powder is then dried using a tray dryer, indirect heating dryer, fluidized bed dryer, vacuum dryer, vibration dryer, flash dryer, etc. to obtain a dry powder.
• the moisture content of the obtained dry powder is preferably 8% by weight or less, more preferably 5% by weight or less.
• the obtained wet or dry powder may be washed with water and/or redispersed, then re-filtered and dried.
• the slurry may be dried using a spray dryer, fluidized bed dryer, or the like to obtain a dry powder.
• the wet or dry powder can be selected appropriately depending on the intended use.
• the masterbatch of the present invention contains the above expandable microspheres and a base resin, and is a foam molding masterbatch that can be used to produce foamed molded articles.
• the base resin contained in the masterbatch of the present invention is a component that is kneaded together with the heat-expandable microspheres to form the masterbatch.
• the base resin has a melt flow rate (hereinafter sometimes referred to as MFR) of more than 60 g/10 min and a melting point lower than the expansion initiation temperature of the heat-expandable microspheres.
• MFR melt flow rate
• the MFR of the base resin is preferably more than 60 g/10 min and not more than 500 g/10 min, more preferably 65 to 400 g/10 min, and even more preferably 70 to 300 g/10 min.
• the MFR of the base resin is measured in accordance with JIS K7210 using a capillary rheometer under conditions of a measurement temperature of 190°C and a load of 2.16 kg.
• the melting point of the base resin there are no particular limitations on the melting point of the base resin, so long as it is equal to or lower than the expansion initiation temperature of the heat-expandable microspheres, but it is preferably at least 5°C lower than the expansion initiation temperature of the heat-expandable microspheres, more preferably at least 10°C lower than the expansion initiation temperature of the heat-expandable microspheres, and even more preferably at least 20°C lower than the expansion initiation temperature of the heat-expandable microspheres.
• the melting point of the base resin is not particularly limited as long as it is below the expansion initiation temperature of the heat-expandable microspheres, but is preferably 60 to 130°C, more preferably 65 to 120°C, even more preferably 70 to 120°C, and especially preferably 75 to 110°C.
• a melting point of 60°C or higher tends to prevent fusion of masterbatches.
• a melting point of 130°C or lower tends to improve expandability.
• the base resin is not particularly limited as long as it has the above-mentioned properties, and examples thereof include ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, silane-crosslinkable ethylene-vinyl acetate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, ethylene-butyl (meth)acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, low-density polyethylene (LDPE), silane-crosslinkable low-density polyethylene, low-density linear low-density polyethylene (L-LDPE), silane-crosslinkable linear Examples of the polymer include olefin polymers such as linear low-density polyethylene
• the base resin preferably contains an olefin polymer, as this improves the dispersibility of the heat-expandable microspheres.
• the content of the olefin units constituting the olefin polymer is not particularly limited, but is preferably 60 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 75 to 100% by weight, and particularly preferably 80 to 100% by weight. When the content is within the above range, the dispersibility of the heat-expandable microspheres tends to be improved.
• the olefin unit is not particularly limited, but is preferably an olefin having 2 to 10 carbon atoms, and preferably contains ethylene.
• the content of the ethylene unit constituting the olefin-based polymer is not particularly limited, but is preferably 50 to 100% by weight, more preferably 60 to 100% by weight, even more preferably 70 to 100% by weight, and particularly preferably 75 to 100% by weight.
• the weight percentage of the olefin-based polymer in the base resin is not particularly limited, but is preferably 10 to 100% by weight, more preferably 30 to 100% by weight, even more preferably 50 to 100% by weight, and particularly preferably 80 to 100% by weight. A weight percentage within the above range tends to improve the dispersibility of heat-expandable microspheres.
• the base resin may also consist of an olefin-based polymer.
• the content of heat-expandable microspheres in the masterbatch of the present invention is not particularly limited, but is preferably 35 to 300 parts by weight, more preferably 50 to 250 parts by weight, even more preferably 60 to 200 parts by weight, and particularly preferably 75 to 150 parts by weight, per 100 parts by weight of base resin.
• a content of 35 parts by weight or more tends to make it easier to maintain the mechanical properties of the matrix component that constitutes the resulting foamed molded article.
• a content of 300 parts by weight or less tends to improve the dispersibility of the heat-expandable microspheres during the production of the molded article.
• the masterbatch of the present invention may further contain other components, such as molding additives including stabilizers, lubricants, fillers, and dispersibility improvers, in addition to the heat-expandable microspheres and base resin.
• the stabilizer is not particularly limited, and examples thereof include phenol-based stabilizers such as pentaerythrityl-tetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] and triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate]; phosphorus-based stabilizers such as tris(mononylphenyl)phosphite and tris(2,4-di-t-butylphenyl)phosphite; and sulfur-based stabilizers such as dilauroyl dipropionate, and these may be used alone or in combination of two or more.
• the lubricant is not particularly limited, and examples thereof include polyethylene wax; glycerin fatty acid esters such as glycerin monostearate and diglycerin stearate; and fatty acids such as stearic acid, and one or more of these may be used in combination.
• the filler is not particularly limited, and examples thereof include plant fibers such as wood flour and kenaf, organic fibers such as polyethylene fibers, polypropylene fibers, nylon fibers, and polyester fibers; inorganic fibers such as glass fibers (including those coated with metal) and carbon fibers (including those coated with metal), potassium titanate, asbestos, silicon carbide, silicon nitride, ceramic fibers, metal fibers, aramid fibers, barium sulfate, calcium sulfate, calcium silicate, calcium carbonate, magnesium carbonate, antimony trioxide, zinc oxide, titanium oxide, magnesium oxide, iron oxide, molybdenum disulfide, magnesium hydroxide, aluminum hydroxide, mica, talc, kaolin, pyrophyllite, bentonite, sericite, zeolite, wollastonite, alumina, clay, ferrite, graphite, gypsum, glass beads, glass balloons, and inorganic particles of quartz, and these may be used alone or
• the specific gravity of the masterbatch of the present invention is not particularly limited, but is preferably 0.8 g/mL or higher, more preferably 0.8 to 1.2 g/mL, even more preferably 0.85 to 1.1 g/mL, and particularly preferably 0.9 to 1.1 g/mL. If the specific gravity is 0.8 g/mL or higher, the amount of expanded heat-expandable microspheres contained in the masterbatch tends to be small, resulting in improved expandability.
• the specific gravity of the masterbatch is determined by the method described in the Examples.
• the expansion ratio of the masterbatch is preferably 5 to 120 times, more preferably 10 to 100 times, and even more preferably 15 to 75 times. If the expansion ratio is 5 times or more, a lightweight foamed molded product tends to be obtained. If the expansion ratio is 120 times or less, a foamed molded product with a good appearance tends to be obtained.
• the cross-sectional shape of the masterbatch of the present invention when cut along a plane perpendicular to its longitudinal direction is determined appropriately depending on the use of the masterbatch, etc., and examples thereof include a circle, an ellipse, a polygon, a star, a hollow circle, etc.
• the length of the masterbatch of the present invention is determined appropriately depending on its application, etc., but is preferably 1 to 5 mm, more preferably 2 to 4 mm, and even more preferably 2.5 to 3.5 mm. A length within this range tends to improve the dispersibility of heat-expandable microspheres during the production of molded articles.
• the major axis length of the cross section of the masterbatch of the present invention taken along a plane perpendicular to its longitudinal direction is determined appropriately depending on the intended use, but is preferably 1 to 5 mm, more preferably 2 to 4 mm, and even more preferably 2.5 to 3.5 mm.
• a major axis length within the above range tends to improve the dispersibility of the heat-expandable microspheres during the production of molded articles.
• the masterbatch of the present invention can be produced by any method that involves mixing heat-expandable microspheres and a base resin, preferably a method that uniformly disperses them.
• the method for producing the masterbatch include a production method that includes the following pre-mixing step (1) and the following pelletizing step (2).
• (1) A pre-kneading step in which a base resin is melted and kneaded in advance using a kneading machine such as a roll, kneader, pressure kneader, Banbury mixer, etc.
• heat-expandable microspheres and, if necessary, other components as described above are added to the molten base resin to prepare a pre-kneaded mixture.
• a pelletizing step in which the pre-kneaded mixture obtained above is fed into an extruder such as a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and the molten mixture is extruded in a desired shape and thickness, and then pelletized using a hot-cut pelletizer.
• an extruder such as a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and the molten mixture is extruded in a desired shape and thickness, and then pelletized using a hot-cut pelletizer.
• the masterbatch of the present invention can be produced by extruding a strand of the desired thickness from an extruder and cutting it to the desired length using a cutter.
• the thickness of the strand can be adjusted by the diameter of the strand die of the extruder, the strand take-up speed, etc.
• the masterbatch must be produced at a temperature lower than the expansion initiation temperature of the heat-expandable microspheres, otherwise the heat-expandable microspheres will expand.
• the masterbatch is produced at a temperature at least 5°C lower than the expansion initiation temperature to prevent the heat-expandable microspheres from expanding.
• composition and foamed molded article contains at least one selected from the heat-expandable microspheres and the masterbatch described above, and a matrix component.
• the composition of the present invention may contain the heat-expandable microspheres and a matrix component. Alternatively, the composition may contain the masterbatch and a matrix component.
• a foamed molded article can be produced by molding the composition of the present invention, and the generation of resin deposits during the production of the foamed molded article can be reduced.
• the matrix component is not particularly limited, and examples thereof include polyvinyl chloride; polyvinylidene chloride; polyvinyl alcohol; ethylene-based copolymers such as ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, and ethylene-butyl (meth)acrylate copolymer; ionomers; polyolefin-based resins such as low-density polyethylene, high-density polyethylene, polypropylene, polybutene, polyisobutylene, polystyrene, and polyterpene; styrene-based copolymers such as styrene-acrylonitrile copolymer and styrene-butadiene-acrylonitrile copolymer; polyacetal; polymethyl methacrylate; cellulose acetate; polycarbon
• the matrix component is not particularly limited, but preferably contains a thermoplastic elastomer in order to achieve the effects of the present invention.
• the matrix component preferably contains at least one selected from an olefin-based elastomer and a styrene-based elastomer.
• the weight proportion of the thermoplastic elastomer in the matrix component is not particularly limited, but is preferably 30 to 100% by weight, more preferably 50 to 100% by weight, and particularly preferably 70 to 100% by weight.
• the content of heat-expandable microspheres in the composition of the present invention is not particularly limited, but is preferably 0.01 to less than 35 parts by weight, more preferably 0.1 to 30 parts by weight, even more preferably 0.5 to 20 parts by weight, and particularly preferably 1 to 15 parts by weight, per 100 parts by weight of the matrix component.
• a content within the above range tends to enable the production of foamed molded articles that are lightweight and have a good appearance.
• the content of the masterbatch in the composition is not particularly limited as long as it corresponds to the content of the heat-expandable microspheres, but is preferably 0.05 to 50 parts by weight, more preferably 0.1 to 30 parts by weight, even more preferably 1 to 20 parts by weight, and particularly preferably 3 to 10 parts by weight, per 100 parts by weight of the matrix component.
• a content of 0.05 parts by weight or more tends to make it easier to obtain a lightweight foamed molded product.
• a content of 50 parts by weight or less tends to make it easier to obtain a foamed molded product with good appearance.
• composition of the present invention may also contain molding additives such as the stabilizers, lubricants, fillers, and dispersibility improvers described above, as long as the effects of the present invention are achieved.
• composition of the present invention can be produced by mixing at least one selected from heat-expandable microspheres and a masterbatch with a matrix resin in a ribbon mixer or a counter-rotor mixer, while controlling the temperature so that it is lower than the expansion initiation temperature of the heat-expandable microspheres and, if necessary, lower than the melting point or softening point of the base component or matrix component of the masterbatch.
• the expansion ratio of the foamed molded article of the present invention is not particularly limited, but is preferably 1.1 to 5 times. When the expansion ratio is 1.1 times or more, the foamed molded article tends to be lightweight. When the expansion ratio is 5 times or less, the deterioration of the mechanical properties of the foamed molded article tends to be reduced.
• the lower limit of the expansion ratio is more preferably 1.2 times, even more preferably 1.4 times, and particularly preferably 1.5 times.
• the upper limit of the expansion ratio is more preferably 4 times, even more preferably 3 times, and particularly preferably 2 times.
• foam molded article of the present invention include, for example, automotive components such as door trim, instrument panels, glass runs, body seals, and bumpers; building materials such as window frame seals, door gaskets, and flooring; shoe soles; and artificial cork.
• automotive components such as door trim, instrument panels, glass runs, body seals, and bumpers
• building materials such as window frame seals, door gaskets, and flooring
• shoe soles such as shoe soles; and artificial cork.
• heat-expandable microspheres of the present invention will now be described in detail. It should be noted that the present invention is not limited to these examples. In the following examples and comparative examples, “%” means “% by weight” and “parts” means “parts by weight” unless otherwise specified. Furthermore, for the sake of simplicity, heat-expandable microspheres will be referred to as “microspheres,” the base resin as “resin,” and the matrix component as “matrix.”
• the sample was heated from 20°C to 350°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 displacement occurred was defined as the maximum expansion temperature (Tmax).
• the specific gravity of the masterbatch was measured using the following measurement method.
• the specific gravity was measured by the immersion method (Archimedes method) using isopropyl alcohol in an atmosphere with an ambient temperature of 25°C and a relative humidity of 50%. Specifically, a 100 mL volumetric flask was emptied and dried, and the volumetric flask weight (WB1) was measured. The weighed volumetric flask was then filled with isopropyl alcohol exactly up to the meniscus, and the weight (WB2) of the volumetric flask filled with 100 mL of isopropyl alcohol was measured.
• the resulting composition was extrusion-molded to obtain a foamed molded article using a Laboplastomill (ME-25, single-screw extruder manufactured by Toyo Seiki Seisakusho, Ltd.) as an extrusion molding machine and a strand die (nozzle diameter 3.0 mm) as a mold.
• the extrusion molding was carried out for 30 minutes, starting 5 minutes after the raw material composition was charged into the extrusion molding machine and extrusion from the strand die began.
• the weight of the resin deposited around the discharge port of the strand die for 30 minutes was measured, and the weight of the resin measured was evaluated based on the following index, with a score of ⁇ or higher being considered a pass.
• ⁇ The amount of eye mucus was 25 mg or less, which was good.
• Good The amount of eye mucus was more than 25 mg and not more than 50 mg, which was fairly good.
• ⁇ The amount of eye mucus exceeded 50 mg, and the result was poor.
• Measurement of specific gravity of foam molded product Measurement was carried out using a Shimadzu top-pan electronic analytical balance (AX200, manufactured by Shimadzu Corporation) in the solid specific gravity measurement mode (immersion method).
• AX200 Shimadzu top-pan electronic analytical balance
• aqueous dispersion medium and the oily mixture were mixed, and the resulting mixture was dispersed in a homomixer (TK Homomixer, manufactured by Plamix Co., Ltd.) at 10,000 rpm for 1 minute to prepare a suspension.
• the suspension was transferred to a 1.5-liter pressure reactor and purged with nitrogen.
• the initial reaction pressure was adjusted to 0.35 MPa, and polymerization was carried out at a polymerization temperature of 60°C for 20 hours while stirring at 80 rpm. After polymerization, the product was filtered and dried to obtain microspheres 1.
• Table 1 The physical properties of the resulting heat-expandable microspheres are shown in Table 1.
• AN acrylonitrile
• SP(AN) 14.4 (cal/cm 3 ) 1/2
• MAN methacrylonitrile
• SP (MAN) 12.7 (cal/cm 3 ) 1/2
• AA acrylic acid
• MAA methacrylic acid
• SP(MAA) 12.5 (cal/cm 3 ) 1/2
• MAAm methacrylamide
• SP(MAAm) 16.3 (cal/cm 3 ) 1/2
• MMA methyl methacrylate
• SP(MMA) 9.9 (cal/cm 3 ) 1/2
• St styrene
• SP(St) 10.6 (cal/cm 3 ) 1/2
• EDMA ethylene glycol dimethacrylate
• SP(EDMA) 11.2 (cal/cm 3 ) 1/2
• the physical properties of the obtained masterbatch are shown in Table 2.
• Resin 1 Ethylene-vinyl acetate copolymer, Ultrathene (registered trademark) 720 manufactured by Tosoh Corporation, specific gravity 0.947, melting point 67°C, melt flow rate 150 g/10 min, olefin unit content 72 wt%, ethylene unit content 72 wt%
• Resin 2 Ethylene-butene copolymer, Excellen (registered trademark) FX558 manufactured by Sumitomo Chemical Co., Ltd., specific gravity 0.89, melting point 79°C, melt flow rate 75 g/10 min, olefin unit content 100 wt%, ethylene unit content 77.8 wt%
• Resin 3 Low-density polyethylene, Petrothene (registered trademark) 353 manufactured by Tosoh Corporation, specific gravity 0.915, melting point 98°C, melt flow rate 145 g/10 min, olefin unit content 100% by weight, ethylene unit content 100% by weight
• Resin 4 E
• Example 1 Six parts by weight of the masterbatch (MB1) obtained in Production Example B1 was mixed with 100 parts by weight of Matrix 1 (an olefin-based elastomer, manufactured by Mitsui Chemicals, Inc., Milastomer® 8032BS, specific gravity 0.89) as a matrix component to obtain a composition.
• Matrix 1 an olefin-based elastomer, manufactured by Mitsui Chemicals, Inc., Milastomer® 8032BS, specific gravity 0.89
• the resulting composition was extruded using the extruder and strand die described in the "Measurement and Evaluation of Residue Amount" section above to obtain a strand-shaped foamed molded article.
• the physical properties of the resulting foamed molded article are shown in Table 4.
• the molding conditions were as follows: the temperature (molding temperature) of the cylinder and strand die of the extruder was set to 200° C., and the screw rotation speed was set to 25 rpm. The residence time of the composition in the molding machine was 3.5 minutes.
• Examples 2 to 8 Comparative Examples 1 to 3> Each foam molded article was obtained in the same manner as in Example 1, except that the production conditions for the foam molded article in Example 1 were changed to those shown in Tables 4 and 5. The physical properties of the obtained foam molded articles are shown in Tables 4 and 5.
• Matrix 1 Olefin-based elastomer, Milastomer (registered trademark) 8032BS manufactured by Mitsui Chemicals, Inc., specific gravity 0.89, A hardness 79
• Matrix 2 styrene-based elastomer, Aronkasei Co., Ltd. AR-SC-30, specific gravity 0.89, A hardness 26
• Tables 4 and 5 show that when the solubility parameter of the polymer contained in the outer shell of heat-expandable microspheres is 13 (cal/cm 3 ) 1/2 or less, the generation of gum can be reduced during foam molding. On the other hand, it is clear that when the solubility parameter of the polymer contained in the outer shell exceeds 13 (cal/cm 3 ) 1/2 , the generation of gunk cannot be reduced when forming a foamed molded article.
• the heat-expandable microspheres of the present invention can be used to produce foamed molded articles by injection molding, extrusion molding, press molding, etc.
• the foamed molded articles obtained can be used as sound-insulating materials, heat-insulating materials, heat-shielding materials, sound-absorbing materials, etc.

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