JP2019044036A - Styrenic resin composition for extrusion foaming, foam sheet, container, and plate-like foam - Google Patents

Abstract

To provide a styrenic resin composition for extrusion foaming capable of obtaining a foam sheet and a plate-like foam having a high expansion ratio and fine bubble cells.SOLUTION: A styrenic resin composition for extrusion foaming contains a styrenic resin (A) and a bisamide compound (B) represented by formula (1), and contains 0.01-10 mass% of the bisamide compound (B) based on 100 mass% of the styrenic resin composition. In formula (1), Rand Rare each independently C1-24 alkyl group, an alkenyl group, an alkynyl group or a hydroxyalkyl group; and n is an integer of 1 to 6.SELECTED DRAWING: None

Description

  The present invention relates to a styrenic resin composition having a high expansion ratio, fine cell cells, and an extruded foam sheet excellent in surface smoothness and a plate-like foam.

  BACKGROUND ART Extruded foamed sheets of styrenic resin are widely used for food packaging containers such as food trays, lunch boxes, instant noodle containers, natto containers, cups, etc. because they are excellent in lightness, rigidity and moldability. In addition, sheet-like extruded foams of styrenic resin have excellent thermal insulation and mechanical strength, so they are used in various fields such as flooring, wall materials, ceiling materials, core materials of tatami mats of general buildings etc. ing.

  As a method of improving the appearance, heat insulation and strength of extruded foam sheets and plate-like extruded foams, it is effective to make the cell size finer, and generally, inorganic fine particles such as talc and calcium carbonate are used as a foaming nucleating agent As, you often adjust the bubble cell.

  In addition, carbon dioxide or nitrogen as a foaming agent is impregnated into a thermoplastic resin in a supercritical state, and bubble nuclei are generated by rapidly reducing the pressure from the pressure above the critical pressure to atmospheric pressure, and then the growth of the bubbles is controlled in the cooling step. The method of obtaining a fine bubble cell by carrying out is disclosed (patent documents 1-3).

JP 10-175249 A U.S. Pat. No. 4,473,665 U.S. Pat. No. 5,158,986

However, in the above-mentioned prior art, the cells of the extruded foam could not be sufficiently refined.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a styrenic resin composition for extrusion and foaming capable of making the cell size of the extruded foam fine.

That is, this invention is a place shown to following (1)-(13).
(1) A styrenic resin composition comprising a styrenic resin (A) and a bisamide compound (B) represented by the following general formula (1), which is based on 100% by mass of the styrenic resin composition, The styrenic resin composition for extrusion foaming containing 0.01-10 mass% of bisamide compounds (B).
[Wherein, in the formula, R ¹ and R ² are the same or different and each is an alkyl group having 1 to 24 carbon atoms, an alkenyl group, an alkynyl group or a hydroxyalkyl group, and n is an integer of 1 to 6. ]

(2) The styrenic resin composition for extrusion foaming as described in said (1) whose content of the said bisamide compound (B) is 0.03-2.5 mass%.
(3) The styrene resin composition for extrusion foaming as described in said (1) or (2) whose content of the said bisamide compound (B) is 0.04-0.6 mass%.
(4) The content of the fatty acid metal salt (C) is 0 to 0.1% by mass with respect to 100% by mass of the styrene resin composition described in any one of the above (1) to (3) Styrenic resin composition for extrusion foaming of
(5) The styrene system for extrusion foaming according to any one of the above (1) to (4), wherein the content ratio of fatty acid metal salt (C) / mass ratio of bisamide compound (B) is 0.6 or less Resin composition.
(6) The styrene resin composition for extrusion foaming according to any one of (1) to (5), wherein R1 and R2 each have 1 to 22 carbon atoms.
(7) The extrusion-forming styrenic resin composition according to any one of the above (1) to (6), wherein R 1 and R 2 each have 16 to 22 carbon atoms.
(8) The styrenic resin composition for extrusion foaming according to any one of the above (1) to (7), wherein the methanol-soluble content of the styrenic resin (A) is 0.2 to 3.0% by mass. object.
(9) The styrene resin composition for extrusion foaming according to any one of (1) to (8) above, wherein the weight average molecular weight of the styrene resin (A) is 100,000 to 700,000.
(10) In the above (1) to (9), the ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) of the styrene resin (A) is 1.5 to 3.5 The styrene resin composition for extrusion foaming according to any one of the items.
(11) A foam sheet obtained by molding the styrenic resin composition for extrusion and foaming according to any one of the above (1) to (10).
(12) A container formed by molding the foam sheet according to (11).
(13) A plate-like foam formed by molding the styrenic resin composition for extrusion and foaming according to any one of (1) to (10).

  By using the styrenic resin composition for extrusion and foaming of the present invention, the cell of the extruded foam can be miniaturized.

17 shows a transmission electron micrograph obtained for Example 5.

  Hereinafter, the present invention will be described in detail.

<Styrene-based resin composition>
The styrenic resin composition of the present invention contains styrenic resin (A) and bisamide compound (B), and may contain components such as fatty acid metal salt (C) and inorganic fine particles (D). Details of each component will be described later.

  The melt mass flow rate (MFR) of the styrenic resin composition of the present invention measured under the conditions of 200 ° C. and 49 N load is preferably 0.1 to 30 g / 10 min, and 0.5 to 25 g / 10 min. Is more preferable, and 1 to 15 g / 10 min is more preferable. When the melt mass flow rate (MFR) is less than 0.1 g / 10 min, the productivity of the extruded foam deteriorates, and when it exceeds 30 g / 10 min, the pressure in the die becomes high when the amount of the foaming agent is increased. It may be difficult to maintain and the expansion ratio may not increase.

  93-130 degreeC of the Vicat softening temperature of the styrene resin composition of this invention is preferable, More preferably, it is 95-125 degreeC, More preferably, it is 100-110 degreeC. When the Vicat softening temperature is less than 93 ° C., the heat resistance of the extruded foam becomes insufficient, and when the Vicat softening temperature exceeds 130 ° C., the molding processability of the extruded foam decreases.

Charpy impact strength of the styrenic resin composition of the present invention is preferably 1.2kJ / ^{m 2} or more, more preferably at 1.4kJ / ^{m 2} or more, still more preferably 1.6kJ / ^{m 2} or more. When the Charpy impact strength is less than 1.2 kJ / m ² , the impact resistance of the extruded foam becomes insufficient. The upper limit of the Charpy impact strength is not particularly specified, but is, for example, 2.5 kJ / m ² .

<Styrene-based resin (A)>
The styrene resin (A) of the present invention preferably has a weight average molecular weight (Mw) of 100,000 to 700,000, and more preferably 150,000 to 600,000, as measured by gel permeation chromatography (GPC). preferable. If the Mw is less than 100,000, the strength of the extruded foam decreases, and if the Mw exceeds 700,000, the flowability decreases, which is not preferable. The Mw of the styrenic resin (A) is adjusted according to the reaction temperature and residence time of the polymerization step, the type and amount of the polymerization initiator, the type and amount of the chain transfer agent, and the type and amount of the solvent used in the polymerization. Can.

  The styrene resin (A) of the present invention preferably has a ratio (Mz / Mw) of Z average molecular weight (Mz) to weight average molecular weight (Mw) of 1.5 to 3.5, and 1.7 to 3 More preferably, it is .0. If the ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) is less than 1.5, the foaming ratio may decrease, and if (Mz / Mw) exceeds 3.5 , The molding processability of the extruded foam is deteriorated.

  It is preferable that it is 0.2-3.0 mass%, and, as for the methanol soluble part of the styrene resin (A) of this invention, it is more preferable that it is 0.3-2.5 mass%, 0.4- Particularly preferred is 2.0% by mass. If the methanol soluble content is less than 0.2% by mass, the formability of the extruded foam may be reduced. When the methanol-soluble content exceeds 3.0% by mass, the strength and heat resistance of the foam may be reduced. The methanol-soluble component as used herein refers to a component soluble in methanol in styrenic resin, and, for example, other than styrene oligomers (styrene dimer, styrene trimer) by-produced in the polymerization step or stifling step of styrenic resin. These components include various additives such as liquid paraffin and silicone oil, residual styrene monomers, and low molecular weight components such as polymerization solvents. As a method of adjusting the methanol soluble content, the method of adjusting the generation amount of styrene oligomers (styrene dimer, styrene trimer) by-produced in the polymerization step depending on the type and amount of the initiator, the addition amount of liquid paraffin and silicone oil And the like.

  The styrene-based resin (A) of the present invention uses a styrene monomer as an essential component (essential component) as a raw material, but in addition to a homopolymer of styrene, 50% by mass or less of a vinyl-based monomer copolymerizable with styrene You may include in the ratio of. Examples of vinyl monomers include substituted styrenes such as α-methylstyrene and p-methylstyrene, acrylic acid, acrylic acid such as methacrylic acid, butyl acrylate and methyl methacrylate, and vinyl cyanide such as acrylonitrile and methacrylonitrile Monomers, maleic anhydride and the like can be mentioned.

  Examples of the polymerization method of the styrene resin (A) of the present invention include known styrene polymerization methods such as bulk polymerization method, solution polymerization and suspension polymerization method. As the solvent, for example, alkylbenzenes such as benzene, toluene, ethylbenzene and xylene, ketones such as acetone and methyl ethyl ketone, aliphatic hydrocarbons such as hexane and cyclohexane, and the like can be used. As a type of reactor, a continuous polymerization system in which a complete mixing type reactor, a plug flow reactor, a loop type reactor and the like are combined is preferably used.

  When producing the styrenic resin (A) of the present invention, from the viewpoint of controlling the polymerization reaction, if necessary, a polymerization solvent, a polymerization initiator such as an organic peroxide, or a chain transfer agent such as an aliphatic mercaptan It can be used.

  As a polymerization initiator, a radical polymerization initiator is preferable, and for example, known and commonly used 1,1-di (t-butylperoxy) cyclohexane, 2,2-di (t-butylperoxy) butane, 2,2- Peroxy ketals such as di (4,4-di-t-butylperoxycyclohexyl) propane and 1,1-di (t-amylperoxy) cyclohexane, cumene hydroperoxide, t-butyl hydroperoxide and the like Alkyl peroxides such as hydroperoxides, t-butyl peroxy acetate, t-amyl peroxy isononanoate, t-butyl cumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, di-t -Dialkyl peroxides such as hexyl peroxide, t-butylperoxyacetal And peroxy esters such as t-butyl peroxybenzoate and t-butyl peroxy isopropyl monocarbonate, and peroxy carbonates such as t-butyl peroxy isopropyl carbonate and polyether tetrakis (t-butyl peroxy carbonate) N, N'-azobis (cyclohexane-1-carbonitrile), N, N'-azobis (2-methylbutyronitrile), N, N'-azobis (2,4-dimethylvaleronitrile), N, N Examples thereof include '-azobis [2- (hydroxymethyl) propionitrile] and the like, and one or more of these may be used in combination.

  Examples of chain transfer agents include monofunctional chain transfer agents such as aliphatic mercaptan, aromatic mercaptan, pentaphenyl ethane, α-methylstyrene dimer and terpinorene, ethylene glycol, tetraethylene glycol, neopentyl glycol, trimethylolpropane And polyfunctional chain transfer agents such as polyfunctional mercaptans obtained by esterifying polyhydric alcohol hydroxyl groups such as pentaerythritol, dipentaerythritol, tripentaerythritol, and sorbitol with thioglycolic acid or mercaptopropionic acid; The species or two or more species can be used in combination.

<Bisamide Compound (B)>
The bisamide compound (B) of the present invention is represented by the following general formula (1).

However, wherein ^R 1, ^{R 2} are the same or different and each is an alkyl group having 1 to 24 carbon atoms, an alkenyl group, an alkynyl group, a hydroxyalkyl group, n represents an integer of 1-6.

  n is preferably an integer of 1 to 5, more preferably an integer of 1 to 4, still more preferably an integer of 1 to 3, and still more preferably 2.

The number of carbon atoms of R ¹ and R ² is preferably 1 to 22, more preferably 6 to 22, still more preferably 10 to 22, and still more preferably 13 to 19, It is further preferable that it is -18.

  Specific examples of the bisamide compound (B) of the above general formula (1) include methylene bis lauric acid amide, methylene bis stearic acid amide, ethylene bis capric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide, ethylene bis Fatty acid bisamides such as behenic acid amide, ethylene bishydroxystearic acid amide, hexamethylene bisstearic acid amide, hexamethylene bis behenic acid amide, hexamethylene bishydroxystearic acid amide, ethylene bis oleic acid amide, ethylene biserucic acid amide And unsaturated fatty acid amides such as hexamethylene bisadipamide and the like, and one or more of these may be used in combination. Also, other bisamides such as N, N'-distearyl adipamide, N, N'-distearyl sebacic acid amide, N, N'-dioleyl adipic acid amide, N, N'-dioleyl sebacic acid amide and the like The compounds can also be used in combination.

  The bisamide compound (B) is 0.01 to 10% by mass, preferably 0.02 to 8% by mass, and preferably 0.03 to 6% by mass with respect to 100% by mass of the styrene resin composition. Is more preferably 0.03 to 2.5% by mass, further preferably 0.04 to 0.6% by mass, and 0.05 to 0.5% by mass Is more preferred. When the amount of the bisamide compound (B) is less than 0.01% by mass, the refining effect of the foam cell can not be obtained. Moreover, when a bisamide compound (B) exceeds 10 mass%, since the strength, the foaming ratio of a foam, and heat resistance fall, it is unpreferable.

  In order to obtain the effects of the present invention, it is preferable that the bisamide compound (B) is dispersed in the form of particles in the styrene resin composition. The dispersed particles of the bisamide compound (B) can be observed, for example, by a transmission electron microscope, and the weight-average equivalent circular particle diameter of the dispersed particles is preferably 1 to 1000 nm. The dispersed particles of the bisamide compound (B) are considered to act as a nucleating agent in the foam formation of the foam, and when the weight-average equivalent circle particle diameter of the dispersed particles is 1 to 1000 nm, the foam of the foam The cell miniaturization effect is particularly effective. As a method of adjusting the weight average circle equivalent particle diameter of dispersed particles of the bisamide compound (B), a styrenic resin composition containing the bisamide compound (B) is melted at a temperature equal to or higher than the melting point of the bisamide compound (B) In the process of cooling, a method of adjusting by the cooling rate is effective. By increasing the cooling rate, it is possible to suppress the coarsening of the dispersed particles, so the dispersed particles become smaller, and conversely, the dispersed particles can be increased by decreasing the cooling rate.

<Fatty acid metal salt (C)>
The fatty acid metal salt (C) of the present invention is a metal of a higher fatty acid represented by the chemical formula R ³ —COOH (wherein R ³ is an alkyl group having 7 to 21 carbon atoms, an alkenyl group, an alkynyl group or a hydroxyalkyl group). Specifically, zinc salts, calcium stearate, magnesium stearate, aluminum stearate, calcium oleate, calcium palmitate, zinc hydroxystearate, aluminum hydroxystearate, zinc behenate, behenic acid Calcium, calcium montanate and the like can be mentioned.

  It is preferable that content of fatty-acid metal salt (C) is 0-0.1 mass% with respect to 100 mass% of styrene-type resin compositions of this invention. The content of the fatty acid metal salt (C) is preferably 0 to 0.05% by mass, and more preferably not containing the fatty acid metal salt (C). When content of a fatty-acid metal salt (C) exceeds 0.1 mass%, the refinement | miniaturization effect of the cell diameter of a foam may be inferior. It is considered that the fatty acid metal salt (C) suppresses the formation of fine particles of the bisamide compound (B). In another expression, the content of fatty acid metal salt (C) / mass ratio of bisamide compound (B) is preferably 0.6 or less, more preferably 0.5 or less, and 0.4 or less. It is more preferable that the ratio be 0.3 or less. When the content of the bisamide compound (B) is relatively large, the refining effect may be exhibited even if the content of the fatty acid metal salt (C) exceeds 0.1% by mass, in which case By making the mass ratio 0.6 or less, the miniaturization effect is more effectively exhibited. The content of the fatty acid metal salt (C) is 0 to 0.1% by mass, and the content of the fatty acid metal salt (C) / the mass ratio of the bisamide compound (B) is 0.6 or less. preferable.

<Inorganic fine particles (D)>
The inorganic fine particles (D) of the present invention are fine particles of an inorganic compound, and examples thereof include talc, calcium carbonate, clay and the like. When the styrene-based resin composition contains inorganic fine particles (D), the inorganic fine particles (D) function as a nucleating agent, and the cell diameter refining effect is particularly high.

  The average particle diameter of the inorganic fine particles (D) is, for example, 0.1 to 100 μm, preferably 0.5 to 30 μm, more preferably 1 to 20 μm, and still more preferably 5 to 15 μm. The average particle diameter of the inorganic fine particles (D) means the particle diameter at an integrated value of 50% in the particle size distribution determined by the laser diffraction / scattering method.

In the styrene resin composition, the content of the inorganic fine particles (D) is preferably 0.01 to 10% by mass, and 0.02 to 5% by mass with respect to 100% by mass of the styrene resin composition. More preferably, 0.05 to 1% by mass is more preferable, and 0.1 to 0.5% by mass is more preferable.
<Other additives>
The styrene-based resin composition of the present invention includes, as additives, phosphorus-based, phenol-based and amine-based antioxidants, liquid paraffin, silicone oil, plasticizers such as polyethylene wax, UV absorbers, antistatic agents, A flame retardant, a coloring agent, a pigment, a deodorant, an antifogging agent etc. can be added as needed.

<Method of Producing Styrene-Based Resin Composition>
The method for producing the styrenic resin composition of the present invention is not particularly limited, and a known blending method can be used. For example, a method of dry blending with a tumbler, a Henschel mixer, a hopper blender, etc., and melt compounding with a single screw extruder, a twin screw extruder, a multiple screw extruder, a Banbury mixer, a kneader, etc. may be mentioned. A masterbatch in which (B) is adjusted to a predetermined amount or more is prepared in advance, and blended with a styrenic resin (A) at the time of production of a foam, or a bisamide compound (B) is styrenic resin (A) It is also possible to adopt a method of adhering to the pellet surface of and adding it.

  Another thermoplastic resin or rubber reinforcing material can be added to the styrenic resin composition of the present invention for the purpose of improving heat resistance, strength and oil resistance, as long as the effects of the present invention are not impaired.

  Specific examples of the thermoplastic resin include polyolefin resins such as polypropylene and propylene-α-olefin copolymer, polyphenylene ether, modified polyphenylene ether, poly L-lactic acid, poly D-lactic acid, poly D, L-lactic acid and the like Aliphatic polyester resins and the like can be mentioned, and one or more of these can be used in combination.

  Specific examples of the rubber reinforcing material include natural rubber, polybutadiene, polyisoprene, polyisobutylene, polychloroprene, polysulfide rubber, thiocor rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, styrene-butadiene block copolymer, Styrene-butadiene-styrene copolymer, styrene-isoprene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogen Styrene rubbers such as added styrene-isoprene block copolymer, hydrogenated styrene-isoprene-styrene block copolymer, and further ethylene propylene rubber, ethylene propylene diene rubber, linear -Based rubbers such as high density polyethylene elastomers, or butadiene-acrylonitrile-styrene-core-shell rubber, methyl methacrylate-butadiene-styrene-core-shell rubber, methyl methacrylate-butyl acrylate-styrene-core-shell rubber, octyl acrylate-butadiene-styrene-core-shell rubber And alkyl acrylate-butadiene-acrylonitrile-styrene-core-shell rubber and high impact polystyrene, and one or more of these can be used in combination.

<Production method of foam sheet, container>
The styrenic resin composition of the present invention can be processed into a foam sheet using a known extrusion foam sheet production method. Specifically, two single-screw extruders and two-screw extruders are arranged in series, melt-kneaded together with a foaming agent by the first extruder, and cooled by the second extruder to a resin temperature of 120 After adjusting to <RTIgt; C </ RTI> to <RTIgt; 180 C, </ RTI> there is a method of releasing to the atmosphere with a circular die and foaming under reduced pressure.

  As the foaming agent, aliphatic hydrocarbons such as propane, normal butane, isobutane, pentane and hexane, cycloaliphatic hydrocarbons such as cyclobutane and cyclopentane, trichlorofluoromethane, dichlorodifluoromethane, 1,1-difluoroethane, Physical blowing agents such as halogenated hydrocarbons such as 1,1-difluoro-chloride and methylene chloride can be used. Further, decomposable foaming agents such as azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, sodium bicarbonate and citric acid, inorganic gases such as carbon dioxide and nitrogen, and water can also be used. These foaming agents can be used as appropriate mixed, but butane is often used industrially, and in view of foam extrudability, secondary formability of foam sheet and foamability, a mixture comprising isobutane and normal butane It is preferred to use butane. Since butane has a low permeation rate to a polystyrene resin, it usually remains in the foam sheet at about 0.5 to 3% by mass immediately after foam extrusion. The remaining amount affects the thickness of the secondary foam in the secondary molding and the thermoforming property, and therefore, the residual amount is appropriately adjusted by setting a certain aging period.

  0.5-4.0 mm is preferable and, as for the thickness of the foam sheet of this invention, 1.0-3.0 mm is more preferable. If the thickness of the foam sheet is less than 0.5 mm, the strength and heat insulation of the container after secondary molding will be reduced. When the thickness of the foam sheet exceeds 4.0 mm, temperature unevenness of the sheet is likely to occur during secondary molding, and the moldability is deteriorated.

The density of the foamed sheet of the present invention is preferably from 30~500kg / ^{m 3,} more preferably 50~300kg / ^{m 3.} If the density of the extruded foam sheet is less than 30 kg / m ³ , the strength is reduced, and if it exceeds 500 kg / m ³ , the heat insulation becomes insufficient.

  The average cell diameter X in the thickness direction, the average cell diameter Y in the extrusion direction, and the average cell diameter Z in the width direction of the foam sheet of the present invention are preferably 0.01 to 500 μm and 0.1 to 300 μm, respectively. It is more preferable that If the average cell diameter is less than 0.01 μm, the density of the extruded foam sheet is increased, which is not preferable in terms of heat insulation. When the average cell diameter exceeds 500 μm, the strength, heat insulation and planar smoothness of the foam sheet are reduced.

  In the foam sheet of the present invention, a surface layer called a so-called skin layer can be provided on the front and back surfaces of the sheet, which has a density higher than that of the central portion in the thickness direction. By providing the skin layer, the strength of the sheet can be increased, and the appearance is finished beautifully. The skin layer can be adjusted by air cooling the surface of the foam sheet immediately after leaving the circular die.

  The foam sheet of the present invention can be improved in moldability, strength and rigidity by laminating a thermoplastic resin sheet or film on one side or both sides. The thermoplastic resin constituting the sheet or film is polystyrene, polystyrene resin such as high impact polystyrene, polypropylene resin, polyester resin, high density polyethylene, low density polyethylene, linear low density polyethylene, ethylene-vinyl acetate Although a copolymer etc. are mentioned, even if it does not use an adhesive layer, it is preferable to use a polystyrene resin which can be laminated and has good recyclability.

  The thickness of the thermoplastic resin sheet or film to be laminated is not particularly limited, but is preferably 10 to 300 μm, more preferably 50 to 250 μm, and particularly preferably 70 to 200 μm. A thicker sheet or film is advantageous for deep-drawing, but too thick is undesirable because it increases the weight of the container.

  The foam sheet of the present invention can be secondarily formed into a container such as a tray, an instant noodle container, a natto container, or a cup by thermoforming such as vacuum forming or pressure forming.

<Method of manufacturing plate-like foam>
The styrenic resin composition of the present invention can be processed into a plate-like foam by using a die having a slit with a rectangular cross section in place of the circular die in the above method for producing an extruded foam sheet.

  In addition, when producing a plate-like foam, known flame retardants can be used. For example, hexabromocyclododecane, dibromoneopentyl glycol, decabromodiphenyl oxide, tetrabromobisphenol A, tetrabromophthalic acid Examples thereof include bromine-based flame retardants such as diol, tetrabromophenol and polypentabromobenzyl acrylate, and phosphorus-based flame retardants such as phosphated urea urea, polyphosphazene, ammonium phosphate, ammonium polyphosphate and red phosphorus.

Preferably the density of the plate-like foam of the present invention is 5 to 100 kg / ^{m 3,} and more preferably 10 to 50 kg / ^{m 3.} When the density of the plate-like foam is less than 5 kg / m ³ , the strength is reduced, and when it exceeds 100 kg / m ³ , the heat insulation becomes insufficient.

  Since the plate-like foam of the present invention is excellent in strength and heat insulation, it can be suitably used for flooring, wall materials, ceiling materials, and core materials of tatami mats of general buildings and the like.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

<Production of styrenic resin A-1 to A-4>
(1) Production of styrenic resin A-1 The following first to third reactors were connected in series to constitute a polymerization step.

1st reactor: 39 L volume mixing type reactor with stirring blades 2nd reactor: 39 L volume mixing type reactor with stirring blades 3rd reactor: 16 L volume plug flow reactor with static mixer

  The conditions of each reactor were as follows.

First reactor: [reaction temperature] 117 ° C
Second reactor: [reaction temperature] 125 ° C.
Third reactor: [Reaction temperature] Adjusted so that a temperature gradient of 130 to 140 ° C appears in the flow direction

  The following were used as raw material solutions.

  Raw material liquid obtained by mixing 0.02 parts by mass of 1,1-di (t-butylperoxy) cyclohexane with 90 parts by mass of styrene and 10 parts by mass of ethylbenzene

The feed solution was continuously fed to the first reactor set at 117 ° C. at a feed rate of 13.5 kg / hr and polymerized, and then continuously charged and polymerized in the second reactor set at 125 ° C. . The polymerization conversion at the outlet of the second reactor was 55%. Further, the polymerization was allowed to proceed to 70% in a third reactor adjusted to have a temperature gradient of 130 to 140 ° C. until the polymerization conversion reached 70%.
The polymerization solution was introduced in series into a two-stage vacuum degassing vessel equipped with a preheater to separate unreacted styrene and ethylbenzene, extruded into strands, cooled and cut into pellets. The temperature of the first stage preheater is set to 200 ° C., the pressure of the vacuum degassing tank is 66.7 kPa, the temperature of the second stage preheater is set to 240 ° C., the pressure of the vacuum degassing tank Was 0.9 kPa. The characteristics of the obtained styrene resin A-1 are shown in Table 1.

(2) Production of styrenic resin A-2 Using the following raw material liquid, the temperature conditions of the first to third reactors were changed as follows, and the supply speed of the raw material liquid was changed to 16.5 kg / hr. Same as production of -1. The characteristics are shown in Table 1.

Raw material liquid
Raw material liquid obtained by mixing 0.020 parts by mass of 2,2-bis (4,4-t-butylperoxycyclohexyl) propane with 92 parts by mass of styrene and 8 parts by mass of ethylbenzene

<Condition>
First reactor: [reaction temperature] 113 ° C
Second reactor: [reaction temperature] 119 ° C.
Third reactor: [Reaction temperature] Adjusted so that a temperature gradient of 170 to 180 ° C is obtained in the flow direction

(3) Production of styrenic resin A-3 Using the following raw material liquid, the temperature conditions of the first to third reactors were changed as follows, and the supply speed of the raw material liquid was changed to 17.6 kg / hr. Same as production of -1. The characteristics are shown in Table 1.

Raw material liquid
Raw material liquid in which 90 parts by mass of styrene and 10 parts by mass of ethylbenzene are mixed

<Condition>
First reactor: [reaction temperature] 150 ° C.
Second reactor: [reaction temperature] 156 ° C.
Third reactor: [Reaction temperature] Adjusted so that a temperature gradient of 170 to 180 ° C is obtained in the flow direction

(4) Production of styrenic resin A-4 Using the following raw material liquid, the temperature conditions of the first to third reactors are changed as follows, and the supply rate of the raw material liquid is 16.5 kg / hr, and the third reaction It was the same as the production of A-1 except that 0.8% by mass of liquid paraffin was added to 100% by mass of the resin at the outlet of the vessel. The characteristics are shown in Table 1.

Raw material liquid
Raw material liquid in which 90 parts by mass of styrene and 10 parts by mass of ethylbenzene are mixed

<Condition>
First reactor: [reaction temperature] 130 ° C
Second reactor: [reaction temperature] 150 ° C.
Third reactor: [Reaction temperature] Adjusted so that a temperature gradient of 140 to 150 ° C was obtained in the flow direction

Examples 1 to 12 and Comparative Examples 1 to 4
The styrenic resin (A-1 to A-4) and bisamide compounds (B-1 to B-3), fatty acid metal salt (C-1) and monoamide compound (E) produced by the above method are shown in Table 2 It mixed by the Henschel mixer by the mass% ratio shown to, and it melt-compounded with the twin-screw extruder (Kobe Steel Works make, KTX30 (alpha)) set to 150-210 degreeC. The die resin temperature at this time was 220 ° C. The resin properties are shown in Table 2.

The following compounds were used as the bisamide compound (B), fatty acid metal salt (C) and monoamide compound (E).
<Bisamide Compound (B)>
B-1: Ethylene bis stearic acid amide (Kao Kao-wax EBFF)
B-2: Ethylenebishydroxystearic acid amide (Nippon Kasei Corporation Suripax B)
B-3: Ethylene bis oleic acid amide (NOF Corporation Alflow AD 281 F)
<Fatty acid metal salt (C)>
C-1: Zinc stearate (Nippon Oil Corp. Zinc Stearate GP)
<Monoamide compound (E)>
E-1: stearic acid amide (manufactured by NOF Corporation Alflow F10)

Next, an extruded foam sheet was manufactured with a tandem extruder having screw diameters of 40 mmφ and 50 mmφ. First, with respect to 100 parts by mass of the above melt compounded resin, 0.5 parts by mass of a talc master batch consisting of 60% by mass of polystyrene and 40% by mass of talc (average particle diameter 9 μm) is uniformly mixed and extruded with a screw diameter of 40 mmφ Supplied to the aircraft. Furthermore, butane gas was injected from the tip of the extruder at a rate of 2.0 parts by mass with respect to 100 parts by mass of the resin as a foaming agent, and melt mixed. The cylinder temperature at this time was 180 to 210 ° C., the resin temperature was 200 to 210 ° C., and the pressure was 12 to 18 MPa.
Thereafter, it is transferred to an extruder with a screw diameter of 50 mmφ through a connecting pipe set at 210 ° C., and the cylinder temperature is 150 to 180 ° C., the resin temperature at the outlet is adjusted to 160 ° C., and the resin pressure is 15 MPa. A circular die of 6 mm diameter and 40 mm diameter was extruded at a discharge rate of 10 kg / hr, drawn along a cooling mandrel with a diameter of 152 mm, pulled out, and cut at one point in the circumference by a cutter to obtain an extruded foam sheet. The characteristics are shown in Table 2.

Example 13
Talc master batch 0.5 mass consisting of 4 mass parts of hexabromocyclododecane, 40 mass% of polystyrene and 40 mass% of talc (average particle diameter 9 μm) with respect to 100 mass parts of the melt-compounded resin in the above examples. After blending the parts, it is supplied to an extruder with a screw diameter of 40 mmφ, 5.0 parts by mass of butane gas is pressed in, the resin temperature at the outlet of the extruder with a screw diameter of 50 mmφ is 140 ° C, the resin pressure is adjusted to 10 MPa, and circular die A plate-like extruded foam was obtained using a die having a slit of rectangular cross section with a thickness of 4 mm and a width direction of 40 mm. The characteristics are shown in Table 2.

  By using the styrenic resin composition of the example, the cell diameter can be reduced while maintaining low foam density, and the obtained foam is excellent in surface smoothness.

  In addition, various physical properties in Table 1-Table 2, and performance evaluation were performed with the following method.

(1) Molecular Weight The number average molecular weight (Mn), the weight average molecular weight (Mw), and the Z average molecular weight (Mz) were measured using gel permeation chromatography (GPC) under the following conditions.
GPC model: Shodex GPC-101 manufactured by Showa Denko KK
Column: Polymer Laboratories PLgel 10μm MIXED-B
Mobile phase: tetrahydrofuran Sample concentration: 0.2% by mass
Temperature: oven 40 ° C, inlet 35 ° C, detector 35 ° C
Detector: Differential Refractometer In the measurement of the molecular weight of the present invention, the molecular weight at each elution time was calculated from the elution curve of monodispersed polystyrene, and calculated as a polystyrene-equivalent molecular weight.

(2) Methanol-soluble component The methanol-soluble component was measured under the following conditions. 1.00 g of a styrene resin is precisely weighed (P), 40 ml of methyl ethyl ketone is added and dissolved, and 400 ml of methanol is rapidly added to precipitate and precipitate methanol insoluble matter (resin component). After standing for about 10 minutes, the solution was gradually filtered through a glass filter to separate methanol-soluble components, dried under reduced pressure at 120 ° C. for 2 hours in a vacuum dryer, then allowed to cool for 25 minutes in a desiccator, and dried The mass N of the methanol insolubles is measured and determined as follows.
Methanol soluble matter (mass%) = (P-N) / P x 100

  The resin properties were evaluated by the following method.

(3) Content of Bisamide Compound (B) The content of the bisamide compound (B) in the resin composition was measured under the following conditions. First, the styrenic resin composition was freeze-crushed, accurately weighed 0.05 g, and then dissolved in 25 mL of chloroform to make a constant volume. Next, the obtained solution was diluted with chloroform, and after adjusting the diluted solution, it was filtered with a PTFE disc filter (0.45 μm), and measured by LC / MS / MS analysis under the following conditions.
LC: LC20A (Shimadzu Corporation)
MS: API 4000 (AB / MDS Sciex)
Column: Cadenza CD-C18 2.0 × 150 mm 3 μm
Column temperature: 45 ° C
Mobile phase: A = 0.1 vol% formic acid, water / methanol = 1/9 solution
B = chloroform Flow rate: 0.3 mL / min
Injection volume: 3 μL
Ionization: ESI method MS detection: positive ion extraction (SRM method)

  In addition, the bisamide compound marketed normally is a mixture of the bisamide from which chain length differs (For example, in the case of ethylene bis stearamide, the mixture of C16-C16, C16-C18, C18-C18). Therefore, a calibration curve of each component having a different chain length is prepared from the component ratio for each chain length previously obtained by GC or the like, and after calculating the quantitative value of each component individually, the total amount thereof is used as the amount of bisamide compound. .

(4) Content of Fatty Acid Metal Salt (C) The content of fatty acid metal salt (C) in the resin composition is determined using the amount of metal element using a fluorescent X-ray elemental analyzer (MESA-500 W) manufactured by Horiba, Ltd. It asked by quantifying.

(5) Weight-average circle equivalent particle diameter Dv of dispersed particles
A molded product (30 mm) obtained by preheating the styrene resin composition for 3 minutes at a temperature of 250 ° C. for 3 minutes with a heat press (MP-2F manufactured by Toyo Seiki Seisakusho), molding for 2 minutes under a pressure of 15 MPa A cross section was cut with a microtome for × 30 mm × 3 mmt, and after staining with RuO ₄ , the central part of the cross section was observed using a transmission electron microscope (H-7500 manufactured by Hitachi, Ltd.). The part stained black corresponds to the bisamide compound (B).

  A photograph obtained by a transmission electron microscope is shown in FIG. From the photograph shown in FIG. 1, a binarization process was performed using an image analysis software "image A" manufactured by Asahi Kasei Engineering Co., Ltd., and the area of the bisamide compound (B) was measured. Since the dispersed particles of the bisamide compound (B) have an irregular shape, the diameter (equivalent circle particle diameter: Di) of the circle having the same area as the bisamide compound (B) is determined, and the weight average equivalent circle particle diameter It asked for (Dv).

(6) Melt mass flow rate Determined under the conditions of 200 ° C. and 49 N load based on JIS K 7210.

(7) Vicat softening temperature Test pieces were prepared using an injection molding machine, and were obtained under the conditions of 50 N load based on JIS K7206.

(8) Charpy impact strength A test piece was prepared using an injection molding machine, and was determined according to JIS K7111.

Foam properties were evaluated by the following method.
(9) Thickness Except for 5 mm on both ends of the extruded foam, positions at intervals of 10 mm in width were taken as measurement points. Using a Dial Thickness Gauge Peacock Model G (manufactured by Ozaki Mfg. Co., Ltd.), measure the thickness to a minimum unit of 0.01 mm, taking care not to deform the test piece, and measure this average value of the extruded foam Thickness (mm).

(10) Density A test piece of 10 cm long × 10 cm wide was carefully cut out of the extruded foam so that the cell structure of the material was not broken, and was calculated from the weight and thickness of the test piece according to the following equation.
Density (kg / m ³ ) = weight of test piece (g) / thickness of test piece (mm) × 100

(11) Foaming Ratio The foaming ratio of the extruded foam was a value obtained by dividing the density (1,050 kg / m ³ ) of the base polystyrene resin by the density of the extruded foam obtained above.

(12) Average cell diameter The average cell diameter X in the thickness direction of the foamed foam, the average cell diameter Y in the extrusion direction, and the average cell diameter Z in the width direction are based on the average chord length measured by the test method of ASTM D2842-06. Calculated.
The average cell diameter X in the thickness direction is a vertical straight line drawn over the entire thickness of the foam in a cross section perpendicular to the extrusion direction observed with a scanning electron microscope, and the average chord is calculated from the length of the straight line and the number of cells intersecting the straight line The length X1 was determined and calculated from X1 / 0.616.
The average cell diameter Y in the extrusion direction divides the vertical cross section in the extrusion direction observed by the scanning electron microscope into four equal parts in the thickness direction, and in each of three line segments near the surface layer, central part in the thickness direction, and near the back surface. The average chord length Y1 is determined from the length of the straight line and the number of cells intersecting the straight line, the average cell diameter of each line segment is calculated from Y1 / 0.616, and the average cell in the extrusion direction is calculated using these arithmetic mean values. The diameter is Y.
The average cell diameter Z in the width direction divides the vertical cross section in the width direction, which is observed with a scanning electron microscope, into four equal parts in the thickness direction, and in each of three line segments near the surface layer, the center in the thickness direction, and the back surface. The average chord length Z1 is determined from the length of the straight line and the number of cells intersecting the straight line, the average cell diameter of each line segment is calculated from Z1 / 0.616, and the average cell in the width direction is calculated using these arithmetic mean values. The diameter is Z.

(13) Gloss Based on JIS K 7105, the upper and lower surfaces (the contact surface of the cooling mandrel and the non-contact surface in the case of a foam sheet) were measured under the condition of an incident angle of 60 degrees, and the average value was taken as the gloss. The higher the degree of gloss, the better the surface smoothness.

Claims (13)

A styrenic resin composition comprising a styrenic resin (A) and a bisamide compound (B) represented by the following general formula (1), wherein the bisamide compound (100% by mass of the styrenic resin composition) The styrenic resin composition for extrusion foams which contains 0.01-10 mass% of B).
[Wherein, in the formula, R ¹ and R ² are the same or different and each is an alkyl group having 1 to 24 carbon atoms, an alkenyl group, an alkynyl group or a hydroxyalkyl group, and n is an integer of 1 to 6. ]   The styrene resin composition for extrusion foaming according to claim 1, wherein the content of the bisamide compound (B) is 0.03 to 2.5% by mass.   The styrene resin composition for extrusion foaming according to claim 1 or 2, wherein the content of the bisamide compound (B) is 0.04 to 0.6% by mass.   The content for fatty-acid metal salt (C) is 0-0.1 mass% with respect to 100 mass% of styrene resin compositions, It is for extrusion foaming of any one of Claims 1-3. Styrenic resin composition.   The styrene resin composition for extrusion foaming according to any one of claims 1 to 4, wherein the content ratio of the fatty acid metal salt (C) to the mass ratio of the bisamide compound (B) is 0.6 or less. The styrene resin composition for extrusion foaming according to any one of claims 1 to 5, wherein R ¹ and R ² each have 1 to 22 carbon atoms. The styrene resin composition for extrusion foaming according to any one of claims 1 to 6, wherein R ¹ and R ² each have 6 to 22 carbon atoms.   The styrene-based resin composition for extrusion and foaming according to any one of claims 1 to 7, wherein the methanol-soluble content of the styrene-based resin (A) is 0.2 to 3.0% by mass.   The styrene resin composition for extrusion foaming according to any one of claims 1 to 8, wherein the weight average molecular weight of the styrene resin (A) is 100,000 to 700,000.   The ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) of the styrene resin (A) is 1.5 to 3.5, any one of claims 1 to 9. The styrenic resin composition for extrusion foaming as described in 4.   The foam sheet formed by shape | molding the styrene resin composition for extrusion foams of any one of Claims 1-10.   The container formed by shape | molding the foam sheet of Claim 11.   The plate-like foam formed by shape | molding the styrene resin composition for extrusion foaming of any one of Claims 1-10.