JP2020164731A - Styrene-based resin flaky foam and method for producing the same - Google Patents

Abstract

To provide a styrene-based resin foam that has excellent workability.SOLUTION: A styrene-based resin flaky foam according to one aspect of the present invention has a true density, a thickness DT, a short side length DS perpendicular to the thickness direction, and a long side length DL, in a particular range, in which the relationship between the short side length DS and the thickness DT is DS≥DT, and the ratio DA/DT between the average length DA, which is the average value of the short side length DS and the long side length DL, and the thickness DT is 5 to 500.SELECTED DRAWING: None

Description

The present invention relates to a styrene-based resin flaky foam and a method for producing the same.

Conventionally, various types of foams have been used as heat insulating materials in structures such as houses and buildings. In recent years, from the viewpoint of energy saving, a material having more excellent heat insulating properties has been demanded. Furthermore, the shortage of human resources has become a major problem at construction sites, and there is a growing demand for heat insulating materials that can be easily constructed.

Conventionally, a styrene resin extruded foam plate is known as a styrene resin foam used for a heat insulating material (for example, Patent Document 1). Further, as a shape other than the plate shape, beads for producing a styrene resin foam by filling a mold of a styrene resin with foam particles of a styrene resin and heating the foam particles to fuse the foam particles with each other. Foamed resin particles in the form have also been developed (for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-129449 JP-A-2018-90707

However, the above-mentioned conventional technique has room for improvement from the viewpoint of workability. One aspect of the present invention is to realize a styrene-based resin foam having excellent workability.

As a result of diligent research conducted by the present inventor in order to solve the above-mentioned problems, it was found that the workability can be improved by processing the styrene resin foam into a specific flake-like shape, and the present invention is completed. I came to let you. The present invention includes the following aspects.

<1> A flake-like foam containing a styrene resin, having a true density of 40 kg / m ³ or more and 150 kg / m ³ or less, and a thickness _DT of 0.01 mm or more and 2.0 mm or less in the thickness direction. vertical short side length _{D S} and the long side length _{D L} is not less 0.5mm or 50.0mm or less, the short side has a length _{D S} and the thickness _{D T} and the relationship _{D S} ≧ _{D T,} and , the ratio _D a / _{D T} of the short side length _{D S} and the average length longer side which is the average value of the length _{D L D a} and the thickness _{D T} is 5 to 500, styrene resin flakes Foam.

<2> The styrene-based resin flake-like foam according to <1>, which has a bulk density of 5 kg / m ³ or more and 25 kg / m ³ or less.

<3> The styrene-based resin flake-like foam according to <1> or <2>, wherein the average cell diameter is 0.01 mm or more and 5.0 mm or less.

<4> The styrene-based resin flake-like foam according to any one of <1> to <3>, wherein the styrene-based resin contains a styrene-acrylonitrile copolymer.

<5> A method for producing a flake-shaped foam containing a styrene resin, wherein the surface of the styrene resin extruded foam obtained by extruding and foaming a styrene resin composition containing a styrene resin and a foaming agent is used. A method for producing a styrene resin flake-like foam, which comprises a step of grinding 0.05 mm or more and 10 mm or less in the thickness direction.

<6> The method for producing a styrene-based resin flaky foam according to <5>, wherein the thickness of the styrene-based resin extruded foam is 10 mm or more and 50 mm or less.

According to one aspect of the present invention, it is possible to provide a styrene-based resin foam having excellent workability.

An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope of the claims, and the technical means disclosed in different embodiments and examples can be used. Embodiments and examples obtained in appropriate combinations are also included in the technical scope of the present invention. In addition, all the academic documents and patent documents described in the present specification are incorporated as references in the present specification. Further, unless otherwise specified in the present specification, "A to B" representing a numerical range is intended to be "A or more and B or less".

[1. Styrene-based resin flake foam]
The styrene-based resin flake-shaped foam according to the embodiment of the present invention is a flake-shaped foam containing a styrene-based resin, has a true density of 40 kg / m ³ or more and 150 kg / m ³ or less, and has a thickness _DT. and at 0.01mm or more 2.0mm or less perpendicular short sides in the thickness direction length _{D S} and the long side length _{D L} is at 0.5mm or 50.0mm or less, the short side length _{D S} and the thickness D relationship between _T is _{D S} ≧ _{D T,} and, the short side length _{D S} and the long side length _{D L} ratio _D a / _{D T} is the mean value mean of the length _{D a} and the thickness _{D T} of However, it is 5 to 500. Hereinafter, the styrene-based resin flake-like foam according to the embodiment of the present invention is also simply referred to as "flake-like foam".

Conventionally, the styrene resin foam used as a heat insulating material has a bead-like or plate-like shape. Although the styrene-based resin foams having these shapes are excellent in heat insulation, machinability and workability, they all have standard products. There is a limit to the degree of freedom in changing the shape at the site where they are actually used. In addition, a great deal of labor and labor was required to cut them and adjust their shapes. There is also a method of pre-cutting them according to the shape to be used in the field, but precise design and great cost are required.

The present inventor has found that these problems can be solved by using a flaky styrene resin foam having a specific shape. As used herein, the term "flake-like" is intended to be flaky, as opposed to bead-like and plate-like. The flake-shaped foam according to the embodiment of the present invention can be formed into a free shape by filling the package or spraying it on the wall. When the beaded foam is applied for filling or spraying, the shape is liable to collapse. On the other hand, if it is a flake-shaped foam, it is easy to maintain its shape when applied to filling or spraying. Therefore, the flake-shaped foam is excellent in workability. The specific shape of the flake-shaped foam will be described later. Further, since the flake-shaped foam is a foam containing a styrene resin, it also has a high degree of heat insulating property. That is, the flake-shaped foam has a specific shape, and because it is a foam, it exerts an excellent effect.

<1-1. Shape and physical properties>
The shape, physical properties, and the like of the flake-shaped foam according to the embodiment of the present invention will be described below. Unless otherwise specified, these values relating to the shape, physical properties, etc. are intended to be values measured by the measuring method described in Examples described later.

The flake-shaped foam has a true density of 40 kg / m ³ or more and 150 kg / m ³ or less. The fact that the true density of the flake-shaped foam is within the above range indicates that the flake-shaped foam is different from the unfoamed resin film, resin piece, or the like. Further, if the true density is within the above range, it is preferable from the viewpoint of heat insulation and light weight. The true density is preferably 50 kg / m ³ or more and 140 kg / m ³ or less, and more preferably 60 kg / m ³ or more and 130 kg / m ³ or less.

The flake-shaped foam has a thickness _DT of 0.01 mm or more and 2.0 mm or less. Also, flake foam, perpendicular short side to the thickness length _{D S} and the long side length _{D L} is 0.5mm or more 50.0mm or less. As used herein, the thickness _DT is intended to be the visually shortest side length of the flaky foam. Since the flake-shaped foam is flaky as described above, the shortest side can be visually determined. Further, the longest line segment in the plane perpendicular to the thickness of the flake-shaped foam is referred to as a long side, and the line segment perpendicularly intersecting at the center of the long side is referred to as a short side. Specific measuring methods for the thickness, short side, and long side will be described in detail in Examples. Short side relationship between the length _{D S} and the thickness _{D T} is the _{D S} ≧ _{D T.} The thickness D _T, if the short side length D _S and the long side length D _L is in the range, easily handled flaky foam, from the viewpoint of workability.

The thickness _DT is preferably 0.05 mm or more and 1.5 mm or less, and more preferably 0.10 mm or more and 1.0 mm or less. Short side length _{D S} and the long side length _{D L} is preferably at not less than 1.0mm 40.0mm or less, and more preferably 1.5mm or more 30.0mm or less.

Furthermore, flaked foam, the ratio _D A / _{D T} of the short side length _{D S} and the average length longer side which is the average value of the length _{D L D A} and the thickness _{D T} is, is 5 to 500 .. When D _A / D _T is 5 or more, the flake-shaped foam is unlike the bead-shaped foam and is not easily collapsed when filled or sprayed. Further, if D _A / D _T is 500 or less, it can be densely filled or sprayed. Average length _{D A} is preferably 0.5mm or more 50.0mm or less, more preferably 1.0mm or more 40.0mm or less, and more preferably 1.5mm or more 30.0mm or less .. D _A / _{D T} is preferably 10 or more, more preferably 20 or more, more preferably 30 or more. _Further, D A / _{D T} is preferably 400 or less, more preferably 300 or less, more preferably 200 or less, particularly preferably 100 or less.

Also, flake foam, the ratio _D L / _{D S} of the short side length _{D S} and the long side length _{D L} of preferably 1 to 10, more preferably 2 to 9. For example, it short side length _{D S} is preferably 0.5mm or more 10.0mm or less, more preferably 1.0mm or more 9.0mm or less, and 1.5mm or more 8.0mm or less Is even more preferable. Long side length _{D L} is preferably less than 8.0 mm 50.0 mm, more preferably less than 9.0 mm 40.0 mm, further not less than 10.0 mm 30.0 mm or less preferable.

The flake-shaped foam preferably has a bulk density of 5 kg / m ³ or more and 25 kg / m ³ or less, more preferably 7 kg / m ³ or more and 23 kg / m ³ or less, and 10 kg / m ³ or more and 20 kg / m. It is more preferably ³ or less. If the bulk density is within the range, it is easy to handle and has excellent workability.

The flake-shaped foam preferably has an average cell diameter of 0.01 mm or more and 5.0 mm or less, more preferably 0.02 mm or more and 4.0 mm or less, and 0.03 mm or more and 3.0 mm or less. Is even more preferable. When the average cell diameter is in this range, it is preferable from the viewpoint of heat insulating properties.

The workability of the flake-shaped foam can be evaluated by, for example, the angle of repose. The angle of repose is preferably 41 degrees or more, more preferably 50 degrees or more, and even more preferably 60 degrees or more. When the angle of repose is 41 degrees or more, the flake-shaped foam does not easily collapse when used by filling or spraying, and the shape can be maintained.

<1-2. Styrene resin>
The flake-shaped foam according to one embodiment of the present invention contains a styrene resin. Examples of the styrene-based resin include homopolymers of styrene-based monomers (polystyrene); copolymers of two or more types of styrene-based monomers; copolymers of styrene-based monomers and other monomers. Can be mentioned.

Examples of the styrene-based monomer include styrene, methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, vinyltoluene, vinylxylene and the like. .. Other monomers include polyfunctional vinyl compounds such as divinylbenzene; acrylate, methacrylic acid; methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate and the like ( Meta) acrylic acid ester compound; vinyl cyanide compound such as (meth) acrylonitrile; diene compound such as butadiene; unsaturated carboxylic acid anhydride such as maleic anhydride and itaconic anhydride; N-methylmaleimide, N-butylmaleimide , N-cyclohexylmaleimide, N-phenylmaleimide, N- (2) -chlorophenylmaleimide, N- (4) -bromophenylmaleimide, N- (1) -naphthylmaleimide and other N-alkyl-substituted maleimide compounds. .. These may be used alone or in combination of two or more.

Further, the styrene resin may be a blend of a homopolymer or copolymer containing the styrene-based monomer and a homopolymer or copolymer of the other monomer. For example, the styrene resin may be blended with a diene rubber reinforced polystyrene, an acrylic rubber reinforced polystyrene, a polyphenylene ether resin, or the like.

As a styrene-based resin, both polystyrene and styrene-acrylonitrile are relatively inexpensive, can be foam-molded with low-pressure steam or the like without using a special method, and have an excellent balance of heat insulating properties, flame retardancy, and cushioning properties. A polymer or a styrene-butyl acrylate copolymer is preferable. In particular, from the viewpoint of heat insulating properties, it is preferable that the styrene resin contains a styrene-acrylonitrile copolymer. Further, when a styrene resin containing a styrene-acrylonitrile copolymer is used, a flake-shaped foam having the above-mentioned shape can be easily obtained.

The styrene resin preferably contains an acrylonitrile component of 5% by weight or more and 45% by weight or less, more preferably 10% by weight or more and 40% by weight or less, and further preferably 15% by weight or more and 35% by weight or less. When the content of the acrylonitrile component in the styrene resin is 5% by weight or more, sufficient heat insulating properties can be obtained. Further, when the content of the acrylonitrile component in the styrene resin is 45% by weight or less, the styrene component is large, so that the melt fluidity at the time of foaming can be ensured, and therefore the foaming can be sufficiently performed.

The styrene-based resin preferably contains the styrene-acrylonitrile copolymer in an amount of 10% by weight or more and 100% by weight or less, more preferably 20% by weight or more and 99% by weight or less, and more than 30% by weight or 98% by weight or less. Is even more preferable. When the content of the styrene-acrylonitrile copolymer in the styrene resin is 10% by weight or more, it is preferable from the viewpoint of obtaining heat insulating properties and obtaining a flaky foam having the above-mentioned shape.

The styrene resin may contain polystyrene in an amount of 0% by weight or more and 90% by weight or less, the styrene-acrylonitrile copolymer in an amount of 10% by weight or more and 100% by weight or less, and polystyrene in an amount of 1% by weight or more and 85% by weight or less. -Acrylonitrile copolymer may be contained in an amount of 15% by weight or more and 99% by weight or less, polystyrene may be contained in an amount of 2% by weight or more and 80% by weight or less, and the styrene-acrylonitrile copolymer may be contained in an amount of 20% by weight or more and 98% by weight or less.

Further, the styrene-acrylonitrile copolymer preferably contains an acrylonitrile component of 10% by weight or more and 45% by weight or less, more preferably 15% by weight or more and 40% by weight or less, and 20% by weight or more and 35% by weight or less. Is even more preferable. When the acrylonitrile component in the styrene-acrylonitrile copolymer is 10% by weight or more, sufficient heat insulating properties can be obtained. Further, when the acrylonitrile component in the styrene-acrylonitrile copolymer is 45% by weight or less, the styrene component is large, so that the melt fluidity at the time of foaming can be ensured, and therefore the foaming can be sufficiently performed.

Further, the styrene resin may be a styrene resin having a branched structure for the purpose of adjusting the melt flow rate, the melt viscosity at the time of molding, the melt tension, and the like. Hereinafter, the melt flow rate is referred to as MFR. Further, two or more kinds of styrene resins having different copolymerization components, molecular weights, molecular weight distributions, branched structures and / or MFRs may be mixed and used.

The MFR of the styrene resin is preferably 1.0 to 15.0 g / 10 minutes, more preferably 2.0 to 10.0 g / 10 minutes. When the MFR is within the above range, it is easy to adjust the heat insulating property, foaming property, physical properties, etc. of the flake-shaped foam to a desired range. In the present specification, MFR is a value measured based on the method A of JIS K7210-1 (2014).

<1-3. Heat ray radiation inhibitor>
The flake-shaped foam may contain a heat ray radiation inhibitor in order to improve the heat insulating property. As used herein, the heat ray radiation inhibitor refers to a substance having the property of reflecting, scattering or absorbing light in the near infrared or infrared region. Examples of the heat ray radiation inhibitor include carbons such as graphite, graphene, carbon black, carbon nanotubes, activated carbon and expanded graphite; and white particles such as titanium oxide, barium sulfate, zinc oxide, aluminum oxide and antimony oxide. These may be used alone or in combination of two or more.

Among these, graphite is preferable because of its high effect of suppressing heat ray radiation on cost. Examples of graphite include scaly graphite, earthy graphite, spheroidal graphite, artificial graphite and the like, and among these, scaly graphite is preferable because it exhibits a high heat ray radiation suppressing effect. In addition, in this specification, the term "scaly" includes scaly, flaky or plate-like. Graphite preferably has a fixed carbon content of 80% or more, and more preferably 85% or more. By setting the fixed carbon content in the above range, a flake-shaped foam having high heat insulating properties can be obtained.

The average particle size of graphite is preferably 15 μm or less, more preferably 10 μm or less. By setting the particle size in the above range, the specific surface area of graphite is increased and the probability of collision with heat ray radiation is increased, so that the effect of suppressing heat ray radiation is enhanced.

The average particle size is measured and analyzed by the laser diffraction scattering method based on the Mie theory based on ISO13320: 2009 and JIS Z8825: 2013, and the cumulative volume with respect to the volume of all particles becomes 50%. It means the particle size (volume average particle size by the laser diffraction scattering method).

The content of graphite is preferably 0.5 parts by weight or more and 10.0 parts by weight or less, more preferably 1.0 part by weight or more and 5.0 parts by weight or less, and 1.5 parts by weight with respect to 100 parts by weight of the styrene resin. More than 3.0 parts by weight is more preferable. When the graphite content is 0.5 parts by weight or more, a sufficient heat ray radiation suppressing effect can be obtained. When the graphite content is 10.0 parts by weight or less, a heat ray radiation suppressing effect corresponding to the content can be obtained, which is cost effective.

<1-4. Flame Retardant>
The flaky foam may contain a flame retardant. The content of the flame retardant is preferably 0.5 parts by weight or more and 8.0 parts by weight or less, more preferably 1.0 part by weight or more and 5.0 parts by weight or less, based on 100 parts by weight of the styrene resin. More preferably, it is 1.5 parts by weight or more and 5.0 parts by weight or less. When the content of the flame retardant is 0.5 parts by weight or more, various good properties such as flame retardancy as a foam can be obtained. Further, when the content of the flame retardant is 8.0 parts by weight or less, sufficient flame retardancy can be imparted without impairing the stability during the production of the foam.

As the flame retardant, a brominated flame retardant is preferably used. Specific examples of the brominated flame retardant include bromine such as tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether. Bisphenol bromide compounds; aliphatic bromine-containing polymers such as brominated styrene-butadiene block copolymers, brominated styrene-butadiene random copolymers, brominated styrene-butadiene graft copolymers; tetrabromocyclooctane, hexabromocyclo Dodecane, tris (2,3-dibromopropyl) isocyanurate and the like can be mentioned. These may be used alone or in combination of two or more.

Of these, a mixed brominated flame retardant of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether, brominated styrene. -Butadiene block copolymer or hexabromocyclododecane is preferably used because it has good extrusion operation and does not adversely affect the heat resistance of the foam. These substances may be used alone or as a mixture.

Further, as the flame retardant aid, a phosphorus-based flame retardant such as a phosphoric acid ester and phosphine oxide can be used in combination as long as the thermal stability is not impaired. Phosphate esters include triphenyl phosphate, tris (tributylbromoneopentyl) phosphate, tricresyl phosphate, trixylyleneyl phosphate, cresildiphenyl phosphate, 2-ethylhexyldiphenyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, Examples thereof include tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate and condensed phosphate ester. Particularly, triphenyl phosphate and tris (tributylbromoneopentyl) phosphate are preferable. As the phosphine oxide, triphenylphosphine oxide is preferable. These may be used alone or in combination of two or more. The preferable amount of the phosphorus-based flame retardant added is 0.1 to 2 parts by weight, more preferably 0.5 to 1.5 parts by weight, based on 100 parts by weight of the styrene resin.

<1-5. Stabilizer>
The flake-like foam may contain a stabilizer in order to suppress the decomposition of the flame retardant and / or the deterioration of the resin. Specific examples of the stabilizer include an epoxy compound, a polyhydric alcohol ester mixture, a phenolic stabilizer, a phosphite stabilizer and the like. These stabilizers are preferably used because they do not reduce the flame retardancy of the foam and improve the thermal stability of the foam.

Examples of the epoxy compound include bisphenol A diglycidyl ether type epoxy resin, cresol novolac type epoxy resin, and phenol novolac type epoxy resin. Examples of the polyhydric alcohol ester mixture include polyhydric alcohols such as pentaerythritol, dipentaerythritol and tripentaerythritol, monovalent carboxylic acids such as acetic acid and propionic acid, and divalent carboxylic acids such as adipic acid and glutamate. A polyhydric alcohol ester which is a reaction product of the above, and a mixture of polyhydric alcohol esters having one or more hydroxyl groups in the molecule can be mentioned. The polyhydric alcohol ester mixture may contain a small amount of the raw material polyhydric alcohol. Examples of the phenolic stabilizer include triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate and pentaerythritol tetrakis [3- (3', 5'-di-tert-). Butyl-4'-hydroxyphenyl) propionate], octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and the like. As phosphite stabilizers, 3,9-bis (2,4-di-tert-butylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane, 3, 9-bis (2,6-di-tert-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane, tetrakis (2,4-di- Examples thereof include tert-butyl-5-methylphenyl) -4,4'-biphenylenediphosphonite. These may be used alone or in combination of two or more.

<1-6. Moldability improver>
The flaky foam may contain a moldability improving agent. For example, if a polyhydric alcohol fatty acid ester is used as the moldability improving agent, it is possible to obtain a sufficient thickness in the extruded foam even when a hydrofluoroolefin described later is used as the foaming agent.

The content of the polyhydric alcohol fatty acid ester is preferably 0.05 parts by weight or more and 5.0 parts by weight or less, and 0.1 parts by weight or more and 3.0 parts by weight or less with respect to 100 parts by weight of the styrene resin. It is more preferable that the amount is 0.5 parts by weight or more and less than 2.0 parts by weight. When the content of the polyhydric alcohol fatty acid ester is 0.05 parts by weight or more, the effect of thickening the extruded foam can be sufficiently obtained. Further, if the content of the polyhydric alcohol fatty acid ester is 5.0 parts by weight or less, the extrudability, foamability and molding stability during production may be impaired, and various properties such as heat resistance of the foam may be deteriorated. There is no risk of doing so.

Examples of the polyhydric alcohol fatty acid ester include higher fatty acids having 10 to 24 carbon atoms and polyvalents such as ethylene glycol, glycerin, 1,2,4-butanetriol, diglycerin, pentaerythritol, sorbitol, erythritol, and hexanetriol. Esters with alcohols can be mentioned. These polyhydric alcohol fatty acid esters may be used alone or in combination of two or more.

Among these, an ester of a higher fatty acid having 10 to 24 carbon atoms and glycerin, in other words, a glycerin fatty acid ester is preferable. A monofatty acid ester, a difatty acid ester, a trifatty acid ester or a tetrafatty acid ester of glycerin is particularly preferable from the viewpoint of availability, price and the like.

Examples of the glycerin fatty acid ester include laurate monoglyceride, laurate diglyceride, laurate triglyceride, palmitic acid monoglyceride, palmitic acid diglyceride, palmitic acid triglyceride, stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, and stearic acid tetraglyceride. Be done.

<1-7. Other additives>
The flake-like foam is a bubble size adjuster such as talc, if necessary; sodium stearate, calcium stearate, magnesium stearate, barium stearate, ethylene bisstearate amide, liquid paraffin, olefin wax, stearyl amide. Lubricants such as compounds; light-resistant stabilizers such as phenol-based antioxidants, phosphorus-based stabilizers, nitrogen-based stabilizers, sulfur-based stabilizers, benzotriazoles, and hindered amines; silica, calcium silicate, wallastonite, kaolin , Clay, mica, calcium carbonate and other inorganic compounds: colorants such as pigments; insect repellents such as anti-termite agents; plastic agents, flame repellents, antistatic agents, binders, humidity control agents, antibacterial agents, etc. You may be. In addition, the foaming agent added when obtaining the extruded foam described later may remain in the flake-shaped foam.

When water and / or alcohols are used as the foaming agent, it is preferable to add a water absorption medium in order to stably perform extrusion foam molding. Specific examples of the water-absorbing medium include a polyacrylate-based polymer, a starch-acrylic acid graft copolymer, a polyvinyl alcohol-based polymer, a vinyl alcohol-acrylate-based copolymer, and an ethylene-vinyl alcohol-based copolymer. Water-absorbent polymers such as acrylonitrile-methyl methacrylate-butadiene copolymers, polyethylene oxide copolymers and derivatives thereof; anhydrous silica (silicon oxide) having a silanol group on the surface [for example, Nippon Aerodil Co., Ltd. AEROSIL manufactured by AEROSIL, etc. are commercially available] and other fine powders having a hydroxyl group on the surface and having a particle size of 1000 nm or less; water-absorbing or water-swellable layered silicates such as smectite and swellable fluoropolymer, and their organic treatment. Products: Porous substances such as zeolite, activated charcoal, alumina, silica gel, porous glass, activated white clay, diatomaceous clay, and bentonite can be mentioned. The amount of the water absorption medium added is appropriately adjusted depending on the amount of water and / or alcohol added, but is preferably 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the styrene resin. The weight part is more preferable.

[2. Method for producing styrene-based resin flaky foam]
The method for producing a styrene-based resin flake-shaped foam according to an embodiment of the present invention is a method for producing a styrene-based resin-containing flake-shaped foam, which comprises a styrene-based resin composition containing a styrene-based resin and a foaming agent. The step of grinding the surface of the styrene resin extruded foam obtained by extrusion foaming in the thickness direction of 0.05 mm or more and 10 mm or less is included. As a result, a flake-shaped foam having a specific shape as described above can be obtained from the styrene-based resin extruded foam. [1. The configuration already described in [Styrene-based resin flake-like foam] will be omitted here.

<2-1. Styrene-based resin extruded foam>
The flake-shaped foam can be obtained from a styrene-based resin extruded foam. The styrene-based resin extruded foam can be obtained by extrusion-foaming a styrene-based resin composition containing a styrene-based resin and a foaming agent. That is, in the method for producing a styrene-based resin flake-shaped foam according to an embodiment of the present invention, a styrene-based resin extruded foam is obtained by extrusion-foaming a styrene-based resin composition containing a styrene-based resin and a foaming agent. The process may be included. In the present specification, the styrene-based resin extruded foam is also simply referred to as "extruded foam", and the styrene-based resin composition is also simply referred to as "resin composition".

Examples of the method for producing the extruded foam include the following methods. First, the styrene-based resin and, if necessary, the above-mentioned various additives are supplied to a heating and melting section of an extruder or the like. At this time, the foaming agent can be added to the styrene resin under high pressure conditions at any stage. Then, a styrene resin composition containing a styrene resin, a foaming agent, and various additives described above, if necessary, is formed as a fluidized gel, cooled to a temperature suitable for extrusion foaming, and then the fluidized gel is passed through a die in a low pressure region. By extruding and foaming, an extruded foam is formed.

As a method of blending various additives with the styrene resin, for example, a method of adding various additives to the styrene resin and mixing them by dry blending; a styrene resin melted from a supply section provided in the middle of the extruder. Method of adding various additives to resin; Using an extruder, kneader, Banbury mixer, roll, etc. in advance, prepare a masterbatch containing various additives in high concentration in styrene resin, and use the masterbatch and styrene type in advance. A method of mixing the resin by dry blending; a method of supplying various additives to the extruder by a supply facility different from the styrene resin can be mentioned.

The heating temperature in the heating and melting section is equal to or higher than the temperature at which the styrene resin used melts. The heating temperature is preferably a temperature at which molecular deterioration of the resin due to the influence of additives or the like is suppressed as much as possible, for example, about 150 ° C. to 260 ° C. The melt-kneading time in the heat-melting section is uniquely defined because it differs depending on the extrusion amount of the styrene resin per unit time and / or the type of extruder used as the heat-melting section and used as the melt-kneading section. This is not possible, and the time required for the styrene resin, the foaming agent, and the additive to be uniformly dispersed and mixed is appropriately set.

As the melt-kneading portion, a mechanism used for ordinary extrusion foaming can be used without particular limitation, and examples thereof include a screw type extruder and the like.

The pressure at which the foaming agent is added or injected is not particularly limited, and may be a pressure higher than the internal pressure of an extruder or the like.

Examples of the method of extrusion foaming include a method of opening the above-mentioned fluidized gel from a high pressure region to a low pressure region through a slit die having an opening having a straight slit shape used for extrusion molding. In this way, an extruded foam is obtained.

The foaming pressure in extrusion foaming is preferably 1.5 MPa or more and less than 3.0 MPa, and more preferably 1.8 MPa or more and 2.7 MPa or less. When the foaming pressure is within this range, the surface of the extruded foam is easily ground into flakes.

Further, the extruded foam may be molded as a plate-shaped foam, that is, an extruded foam plate. For example, using a molding die in which the extruded foam obtained as described above is placed in close contact with or in contact with the slit die, a molding roll installed adjacent to the downstream side of the molding die, or the like is used. A plate-shaped foam having a large cross-sectional area can be molded. By adjusting the flow surface shape of the molding die and adjusting the temperature of the die, the desired cross-sectional shape of the foam, the surface property of the foam, and the quality of the foam can be obtained.

The thickness of the extruded foam is preferably 10 mm or more and 50 mm or less, and more preferably 20 mm or more and 40 mm or less. When the thickness of the extruded foam is within this range, flaky foam can be easily and efficiently obtained in the grinding step described later.

<2-2. Foaming agent>
Examples of the foaming agent include hydrofluoroolefins, saturated hydrocarbons having 3 to 5 carbon atoms, and other foaming agents. From the viewpoint of improving the heat insulating property of the extruded foam, it is preferable to use a hydrofluoroolefin as a foaming agent. These foaming agents may be used alone or in combination of two or more. For example, a saturated hydrocarbon having 3 to 5 carbon atoms and a hydrofluoroolefin may be used in combination.

As the hydrofluoroolefin, for example, tetrafluoropropene is preferable from the viewpoint of low thermal conductivity of the gas and safety. Specifically, trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze), cis-1,3,3,3-tetrafluoropropene (cis-HFO-1234ze), 2,3. Examples thereof include 3,3-tetrafluoropropene (trans-HFO-1234yf). These hydrofluoroolefins may be used alone or in combination of two or more.

Further, as the hydrofluoroolefin, a chlorinated hydrofluoroolefin, that is, a hydrochlorofluoroolefin may be used.

The amount of the hydrofluoroolefin added is preferably 2.0 parts by weight or more and 14.0 parts by weight or less, more preferably 3.0 parts by weight or more and 13.0 parts by weight or less, based on 100 parts by weight of the styrene resin. More preferably, it is 0 parts by weight or more and 12.0 parts by weight or less. When the amount of the hydrofluoroolefin added is 2.0 parts by weight or more, the effect of improving the heat insulating property can be expected. Further, when the amount of the hydrofluoroolefin added is 14.0 parts by weight or less, the hydrofluoroolefin is separated from the resin melt during extrusion foaming, and spot holes are generated on the surface of the extrusion foam, and it is independent. It is possible to avoid a decrease in the bubble ratio and impairing the heat insulating property. The spot pores are intended to be traces of a local mass of hydrofluoroolefin penetrating the surface of the extruded foam and being released to the outside air.

Hydrofluoroolefins are environmentally friendly foaming agents with zero or extremely low ozone depletion potentials and very low global warming potentials. Moreover, since hydrofluoroolefins have low thermal conductivity in a gaseous state and are flame-retardant, they can be used as a foaming agent for extruded foams to impart excellent heat insulating properties and flame-retardant properties to the extruded foams. can do.

When a hydrofluoroolefin having low solubility in a styrene resin such as tetrafluoropropene is used, the hydrofluoroolefin is separated and / or vaporized from the resin melt as the amount of addition is increased. Hydrofluoroolefins can be nucleation points. This means that the bubbles in the foam are miniaturized; the plasticizing effect on the resin melt is reduced by reducing the foaming agent remaining in the resin; the resin melt due to the latent heat of vaporization of the foaming agent. It can lead to cooling and solidification. As a result, it tends to be difficult to increase the thickness of the extruded foam. In this case, it is preferable to use a moldability improving agent in combination as described above.

Examples of saturated hydrocarbons having 3 to 5 carbon atoms include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane and the like. Among these saturated hydrocarbons having 3 to 5 carbon atoms, propane, n-butane, i-butane, or a mixture thereof is preferable from the viewpoint of foamability. Further, from the viewpoint of heat insulating properties of the foam, n-butane, i-butane, or a mixture thereof is preferable, and i-butane is particularly preferable. The i-butane is also hereinafter referred to as "isobutane".

Depending on the desired foaming ratio, flame retardancy, and other properties of the foam, the amount of hydrofluoroolefin and / or saturated hydrocarbon having 3 to 5 carbon atoms added may be limited. If the addition amount is out of the desired range, the extrusion foam moldability and the like may not be sufficient. In this case, further, by using another foaming agent, a plasticizing effect and / or a co-foaming effect at the time of producing the foam can be obtained. As a result, the extrusion pressure can be reduced, so that the foam can be stably produced.

Other effervescent agents include, for example, ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, tetrahydropyran; dimethylketone, methylethylketone. , Diethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, methyl-i-butyl ketone, methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-propyl ketone, ethyl-n-butyl ketone, etc. Ketones; saturated alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t-butyl alcohol; methyl formic acid ester, ethyl formic acid ester, propyl formic acid ester , Carborate esters such as butyl formic acid, amyl ester of formic acid, methyl propionic acid ester, ethyl propionic acid ester; organic foaming agents such as alkyl halides such as methyl chloride and ethyl chloride. Inorganic foaming agents such as water and carbon dioxide, chemical foaming agents such as azo compounds and tetrazole can also be used. These other foaming agents may be used alone or in combination of two or more.

Among other foaming agents, saturated alcohols having 1 to 4 carbon atoms, dimethyl ether, diethyl ether, methyl ethyl ether, methyl chloride, ethyl chloride and the like are preferable from the viewpoint of foamability and foam formability. Further, water and carbon dioxide are preferable from the viewpoint of flammability of the foaming agent, flame retardancy of the foam, heat insulating property, and the like. Of these, dimethyl ether is particularly preferable from the viewpoint of plasticizing effect. Water is particularly preferable from the viewpoint of improving the heat insulating property by controlling the cost and the bubble diameter.

From the above, the foaming agent preferably contains at least one selected from the group consisting of saturated hydrocarbons having 3 to 5 carbon atoms, hydrofluoroolefins and hydrochlorofluoroolefins. Further, it is more preferable that the foaming agent further contains at least one selected from the group consisting of ethyl chloride, methyl chloride and dimethyl ether.

The total amount of the foaming agent added is preferably 2 to 20 parts by weight, more preferably 2 to 15 parts by weight, based on 100 parts by weight of the styrene resin. When the amount of the foaming agent added is 2 parts by weight or more, the foaming ratio can be sufficiently increased, so that the properties such as light weight and heat insulating property as a resin foam are likely to be exhibited. When the amount of the foaming agent added is 20 parts by weight or less, it is possible to prevent the occurrence of defects such as voids in the foam.

<2-3. Grinding process>
The grinding step is a step of grinding the surface of the extruded foam described above by 0.05 mm or more and 10 mm or less in the thickness direction. This makes it possible to obtain a flaky foam having the above-mentioned specific shape. Grinding can be performed by, for example, a cutter, scissors, a tipped saw, a plane or the like. Grinding is preferably performed in the thickness direction of the extruded foam of 0.1 mm or more and 8 mm or less, and more preferably 0.5 mm or more and 5 mm or less.

[3. Use]
The flake-shaped foam can be suitably used as, for example, a heat insulating material; a sound absorbing material; a core material of a vacuum heat insulating material; a cushioning material; a filler such as a cushion, a pillow, and winter clothes. The flake-shaped foam can be blown into the target space, or can be blown onto a wall or the like. Alternatively, the flaky foam can be used again in agglomerates. Further, the flaky foam can be used by packaging, for example, by packing it in a bag made of an elastic material. As described above, since the flake-shaped foam does not easily collapse, it is excellent in workability and therefore can be applied to various uses.

Examples of the present invention will be described below, but the present invention is not limited thereto.

〔material〕
The raw materials used in the examples and comparative examples are as follows.

○ Base resin ・ Styrene-based resin A [Styrene-acrylonitrile copolymer: manufactured by Denka Co., Ltd., Denka AS GR-AT-5S, acrylonitrile component amount 25% by weight, MFR 8.0 g / 10 minutes]
-Styrene-based resin B [Styrene-acrylonitrile copolymer: manufactured by Denka Co., Ltd., Denka AS AS-EXS, acrylonitrile component amount 25% by weight, MFR 2.1 g / 10 minutes]
-Styrene-based resin C [Styrene-acrylonitrile copolymer: manufactured by Denka Co., Ltd., Denka AS AS-XGS, acrylonitrile component amount 28% by weight, MFR 2.1 g / 10 minutes]
-Styrene resin D [Polystyrene: PS Japan Corporation, G9401, MFR 2.2 g / 10 minutes]
○ Heat ray radiation inhibitor ・ Graphite [Manufactured by Marutoyo Casting Co., Ltd., M-885: scaly graphite, primary particle size 5.5 μm, fixed carbon content 89%]
○ Flame retardant ・ Mixed brominated flame retardant with tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether [Daiichi Kogyo Made by Pharmaceutical Co., Ltd., GR-125P]
○ Flame retardant, triphenylphosphine oxide [Sumitomo Corporation Chemical]
○ Stabilizer ・ Bisphenol-A-glycidyl ether [manufactured by ADEKA Corporation, EP-13]
・ Dipentaerythritol-adipic acid reaction mixture [Ajinomoto Fine-Techno Co., Ltd., Plenizer ST210]
-Triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate [Songwon Japan Co., Ltd., Sonnox 2450FF]
○ Other additives ・ Talc [Talcan powder PK-Z manufactured by Hayashi Kasei Co., Ltd.]
・ Calcium stearate [Sakai Chemical Industry Co., Ltd., SCP]
・ Bentonite [Made by Hojun Co., Ltd., Wenger Bright 11K]
・ Silica [Carplex BS-304F, manufactured by Evonik Degussa Japan Co., Ltd.]
-Ethylene bisstearic acid amide [manufactured by NOF CORPORATION, Alflo H-50S]
・ Stearic acid monoglyceride [Riken Vitamin Co., Ltd., Rikemar S-100P]
○ Foaming agent, HFO-1234ze [Manufactured by Honeywell Japan Co., Ltd.]
・ Dimethyl ether [manufactured by Iwatani Corporation]
・ Isobutane [Mitsui Chemicals, Inc.]
・ Ethyl chloride [manufactured by Nippon Tokushu Kagaku Kogyo Co., Ltd.]
・ Water [Tap water, Settsu City, Osaka Prefecture]
〔Measuring method〕
Regarding the flake-shaped foams and the like according to Examples and Comparative Examples, the acrylonitrile content, true density, bulk density, thickness, long side length and short side length, average cell diameter, and rest of the styrene resin are according to the following methods. The angle was measured. The measurable items were also measured for the powdered grinding chips, beaded foams, and film pieces according to the comparative example.

(1) Acrylonitrile content in styrene resin [% by weight]
The obtained flaky foam was analyzed by IR under the following conditions.
-Device: FT-IR [Perkin Elmer, Spectrometer Model Spectrum One]
-Measurement range: 4000-400 cm ^-1
-Detector: DTGS
・ Number of integrations: 4 times ・ Resolution: 4.00 cm ^-1
In the obtained analysis results, the acrylonitrile content was determined from the absorbance of each of the acrylonitrile-derived peak appearing near 2240 cm ^-1 and the styrene-derived peak appearing near 1600 cm ^-1 .

(2) True density [kg / m ³ ]
The obtained flake-shaped foam is subjected to the conditions of the standard temperature condition class 3 (23 ° C. ± 5 ° C.) and the standard humidity state class 3 (50 ^{+ 20, -10} % RH) specified in JIS K 7100. After allowing to stand for 24 hours, the weight [g] was measured. Then, the weighed flaky foam was submerged in an appropriate amount of ethanol taken in a measuring cylinder. The volume of the flake-shaped foam [cm ³ ] was measured from the change in the ethanol liquid level before and after submerging the flake-shaped foam.

The true density of the flake-shaped foam was determined from the following formula (I).
True density [g / cm ³ ] = weight [g] / volume [cm ³ ] ... (I)
The unit of the obtained true density was converted into kg / m ³ .

(3) Bulk density [kg / m ³ ]
The obtained flake-shaped foam is subjected to the conditions of standard temperature condition 3 grade (23 ° C ± 5 ° C) and standard humidity condition 3 grade (50 ^{+ 20, -10} % RH) specified in JIS K 7100. After allowing to stand for 24 hours, it was placed in a measuring cylinder so that the volume was 2000 cm ^3, and the weight was measured.

The bulk density of the flake-shaped foam was determined from the following formula (II).
Bulk density [g / cm ³ ] = weight [g] / 2000 [cm ³ ] ... (II)
The unit of the obtained bulk density was converted into kg / m ³ .

(4) Thickness _DT [mm]
The thickness of a total of 10 flaky foams randomly extracted was measured using a micrometer [Mitutoyo Co., Ltd., Digimatic Micrometer MDC-25SX]. The measurement result was the average value of the values of the 10 points measured. The thickness _DT refers to the length of one side of the flake-shaped foam, which is the shortest visually.

(5) long side length _{D L} and a short side length _D S [mm]
The longest line segment on the plane perpendicular to the thickness of the flake-shaped foam at a total of 10 points whose thickness was measured in (4) is the long side, and the line segment that intersects vertically at the center of the long side is the short side, and their lengths. The size was measured using Nogisu [Mitutoyo Co., Ltd., M-type standard Nogisu 530-101 N15]. The measurement result was the average value of the values of 10 points measured on each of the long side and the short side.

(6) Average bubble diameter [mm]
A total of 10 flaky foams randomly extracted were evaluated using a microscope [DIGITAL MICROSCOPE VHX-900, manufactured by KEYENCE Co., Ltd.] as described below.

A plane perpendicular to the thickness of the obtained flake-shaped foam was observed with a microscope, and a 150-fold magnified photograph was taken. Three straight lines of 2 mm were arbitrarily drawn in each of the long side direction and the short side direction of the enlarged photograph, and the number a of bubbles in contact with the straight lines was measured. From the measured number of bubbles a, the bubble diameter was determined by the following formula (III).
Bubble diameter (mm) = 2 (mm) x 6 / number of bubbles a ... (III)
The bubble diameter was measured in the same manner on the opposite plane. The average value of the bubble diameters of the styrene-based resin flake-shaped foams having a total of 10 points × 2 planes measured in this way was taken as the average bubble diameter of the flake-shaped foams.

(7) Angle of repose [degree]
From a height of 200 mm, a flake-shaped foam was dropped by 1000 cm ³ from a hole of Φ40 mm toward a circular pedestal of Φ100 mm. The angle of the slope of the flaky foam deposited in a mountain shape on the pedestal was measured and evaluated as the angle of repose.

The angle of repose was evaluated as follows.
1 point: angle of repose 0 to 20 degrees 2 points: angle of repose 21-40 degrees 3 points: angle of repose 41-60 degrees 4 points: angle of repose 61-80 degrees 5 points: angle of repose 81-90 degrees If it is 4 points or more, it will not collapse, 3 points will not collapse easily, and 2 points or less will all collapse. The value of the angle of repose is a value rounded to the first decimal place.

[Examples and Comparative Examples]
For Examples and Comparative Examples, graphite was added by a masterbatch made according to the following procedure.

<Manufacturing Example 1: Preparation of Graphite Masterbatch A>
For 100 parts by weight of styrene resin A [styrene-acrylonitrile copolymer: manufactured by Denka Co., Ltd., Denka AS GR-AT-5S], which is a base resin, and 100 parts by weight of styrene resin A in a Banbury mixer. , Styrene [manufactured by Marutoyo Casting Co., Ltd., M-885] 102 parts by weight and ethylene bisstearic acid amide [manufactured by Nichiyu Co., Ltd., Alflo H-50S] 2.0 parts by weight, 5 kgf The mixture was melt-kneaded for 20 minutes without heating and cooling under a load of / cm ² . At this time, the resin temperature was measured and found to be 185 ° C. The obtained resin mixture was supplied to the ruder and extruded at a discharge rate of 250 kg / hr through a die having a small hole attached to the tip of the ruder. The extruded strand-shaped resin mixture was cooled and solidified in a water tank at 30 ° C., and then cut to obtain Graphite Masterbatch A.

<Manufacturing Example 2: Preparation of Graphite Masterbatch B>
In Production Example 1, the same as in Production Example 1 except that styrene resin B [styrene-acrylonitrile copolymer: manufactured by Denka Co., Ltd., Denka AS AS-EXS] was used instead of styrene resin A. A styrene masterbatch B was obtained.

<Manufacturing Example 3: Fabrication of Graphite Masterbatch C>
In Production Example 1, the same as in Production Example 1 except that styrene resin C [styrene-acrylonitrile copolymer: manufactured by Denka Co., Ltd., Denka AS AS-XGS] was used instead of styrene resin A. A graphite masterbatch C was obtained.

<Manufacturing Example 4: Production of Graphite Masterbatch D>
A graphite masterbatch D was obtained in the same manner as in Production Example 1 except that the styrene resin D [polystyrene: manufactured by PS Japan Corporation, G9401] was used instead of the styrene resin A in Production Example 1.

<Example 1>
[Preparation of resin composition]
A styrene resin A [styrene-acrylonitrile copolymer: manufactured by Denka Co., Ltd., Denka AS GR-AT-5S] 96.6 parts by weight, and a graphite master batch A5 as a radiation inhibitor master batch. 0 parts by weight, as a flame retardant, a mixed brominated flame retardant of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether [ Daiichi Kogyo Seiyaku Co., Ltd., GR-125P] 3.0 parts by weight, triphenylphosphine oxide [Sumitomo Shoji Chemical] 1.0 part by weight as a flame retardant, talc [Hayashi Kasei Co., Ltd. ), Talcan powder PK-Z] 3.0 parts by weight, bisphenol-A-glycidyl ether as a stabilizer [made by ADEKA Co., Ltd., EP-13] 0.20 parts by weight, triethylene glycol-bis-3- ( 3-t-Butyl-4-hydroxy-5-methylphenyl) propionate [Songwon Japan Co., Ltd., Sonnox 2450FF] 0.20 parts by weight, dipentaerythritol-adipic acid reaction mixture [Ajinomoto Fine Techno, Plenizer ST210] 0.10 parts by weight, calcium stearate [manufactured by Sakai Chemical Industry Co., Ltd., SC-P] 0.20 parts by weight as a lubricant, and monoglyceride stearate [manufactured by RIKEN Vitamin Co., Ltd. S-100P] 0.50 parts by weight was dry blended.

[Preparation of flaky foam]
The obtained resin composition is transferred to an extruder in which a single-screw extruder (first extruder) having a diameter of 65 mm, a single-screw extruder (second extruder) having a diameter of 90 mm, and a cooler are connected in series. It was supplied at 50 kg / hr. The resin composition supplied to the first extruder is melted or plasticized by heating to a resin temperature of 250 ° C., kneaded, and then a foaming agent (3.0 parts by weight of isobutane with respect to 100 parts by weight of the base resin). And 6.0 parts by weight of ethyl chloride) was press-fitted into the resin composition near the tip of the first extruder.

Then, the resin temperature was cooled to 110 ° C. in the second extruder and the cooler connected to the first extruder. The resin composition was extruded and foamed into the atmosphere from a 50 mm wide rectangular cross-section mouthpiece (slit die) provided at the tip of the cooler. The thickness of the mouthpiece was adjusted so that the foaming pressure was 2.5 MPa. Then, an extruded foam plate having a cross-sectional shape having a thickness of 30 mm and a width of 150 mm was obtained by a molding die installed in close contact with the mouthpiece and a molding roll installed on the downstream side thereof.

The obtained extruded foam plate was cured at room temperature for 1 day. Then, the upper and lower planes of the extruded foam plate were ground by 5 mm in the thickness direction for each plane using a tip saw to obtain a flake-shaped foam. The tip saw at the time of grinding moves while rotating the blade from the side extruded first to the side extruded later along the extrusion direction of the extruded foam plate with the blade direction perpendicular to the plane of the extruded foam plate. I let you. Table 1 shows the evaluation results of the obtained flake-shaped foam.

<Examples 2 to 11>
As shown in Tables 1 and 2, flaky foam was obtained by the same operation as in Example 1 except that the types, addition amounts and / or production conditions of various formulations were changed.

<Comparative example 1>
As a result of grinding XPS [styrene resin extruded foam: Kaneka Corporation, Kaneka Foam (registered trademark) Super E-BK (thickness 50 mm)] in the same manner as in Example 1, powdery grinding chips were obtained. It was. This grinding debris was evaluated in the same manner as in Example 1.

<Comparative example 2>
As shown in Table 3, an extruded foam plate was obtained by the same operation as in Example 1 except that the types, addition amounts and / or production conditions of various formulations were changed. The obtained extruded foam plate was cured at room temperature for 1 day. Then, the upper and lower surfaces of the extruded foam were cut into desired sizes using a cutter and scissors within a range of up to 5 mm in the thickness direction for each plane to obtain foam pieces having the shapes shown in Table 3. The foam piece was evaluated in the same manner as in Example 1.

<Comparative example 3>
EPS [Styrene-based resin pre-foamed particles: Kaneka Corporation, Kaneka Corporation (registered trademark) DF (30-fold foamed product)] was evaluated in the same manner as in Example 1.

<Comparative example 4>
A resin film was obtained by heating and pressing styrene-based resin A [styrene-acrylonitrile copolymer: manufactured by Denka Co., Ltd., Denka AS GR-AT-5S] at 200 ° C. and 50 kgf / cm ² for 5 minutes. The resin film was cut into a desired size using a cutter and scissors to obtain a film piece having the shape shown in Table 3. The film piece was evaluated in the same manner as in Example 1.

〔Measurement result〕
Tables 1 to 3 show the physical properties of the flake-shaped foams and the like obtained in Examples 1 to 11 and Comparative Examples 1 to 4. As described above, graphite was added in advance as a masterbatch of styrene-based resin at the time of preparation of the resin composition. When the masterbatch was used, the base resin was 100 parts by weight in total with the base resin contained in the masterbatch.

The flaky foam having a specific shape of Examples 1 to 11 had an angle of repose of 50 degrees or more, and an angle of repose evaluation point of 3 points or more. That is, it was found that these flake-shaped foams are hard to collapse and have excellent workability. On the other hand, powdered grinding dust of Comparative Example 1, the thickness _{D T} of Comparative Example 2 is more than 2.0 _mm, the foam piece D A / _{D T} is less than 5, bead foam of Comparative Example 3, repose The angle was less than 40 degrees or less than 30 degrees. Further, since the film piece of Comparative Example 4 was not foamed, the true density was high, and this film piece also had an angle of repose of less than 30 degrees. That is, it was found that the samples of Comparative Examples 1 to 4 were inferior in workability.

Since the flake-shaped foam according to one aspect of the present invention is excellent in workability, it can be used as, for example, a heat insulating material, a sound absorbing material, a core material of a vacuum heat insulating material, a cushioning material, and a filler.

Claims (6)

A flake-like foam containing a styrene resin,
The true density is 40 kg / m ³ or more and 150 kg / m ³ or less.
The thickness _DT is 0.01 mm or more and 2.0 mm or less.
Vertical short side in the thickness direction length _{D S} and the long side length _{D L} is at 0.5mm or 50.0mm or less,
Short side relationship between the length _{D S} and the thickness _{D T} is _{D S} ≧ _{D T,} and, the short side length _D average length _S and the long side is an average value of the length _{D L D A} and the thickness D the ratio _D a / _{D T} and _T is 5 to 500, styrene resin flake foam. The styrene-based resin flake-like foam according to claim 1, which has a bulk density of 5 kg / m ³ or more and 25 kg / m ³ or less. The styrene-based resin flake-like foam according to claim 1 or 2, wherein the average cell diameter is 0.01 mm or more and 5.0 mm or less. The styrene-based resin flake-like foam according to any one of claims 1 to 3, wherein the styrene-based resin contains a styrene-acrylonitrile copolymer. A method for producing a flake-shaped foam containing a styrene resin.
Styrene-based resin flakes including a step of grinding the surface of a styrene-based resin extruded foam obtained by extrusion-foaming a styrene-based resin composition containing a styrene-based resin and a foaming agent from 0.05 mm to 10 mm in the thickness direction. A method for producing a foam. The method for producing a styrene-based resin flake-shaped foam according to claim 5, wherein the thickness of the styrene-based resin extruded foam is 10 mm or more and 50 mm or less.