Method for producing polystyrene-based resin extruded foam sheet

Abstract

To provide a method for producing a polystyrene-based resin extruded foam sheet capable of producing an extruded foam sheet with desired flame retardancy and heat resistance while exhibiting excellent production stability.SOLUTION: There is provided a method for producing a polystyrene-based resin extruded foam sheet, comprising the steps of: extruding and foaming a molten foaming resin composition containing a base resin including a polystyrene resin, a flame retardant, and a physical foaming agent; and forming the resulting extrudate into a sheet using a forming implement, wherein the polystyrene-based resin extruded foam sheet has an apparent density of 15 kg / m3 or more and 100 kg / m3 or less. The resin composition contains a brominated styrene-butadiene copolymer as a brominated flame retardant and one or more metal phosphinate selected from the group consisting of phosphoric acid metal salts, diphosphoric acid metal salts, and mixtures thereof as a phosphorus flame retardant. The amount of added brominated styrene-butadiene copolymer is 0.5 pts.mass or more and 12 pts.mass or less with respect to 100 pts.mass of the base resin, and the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer is 0.05 or more and 0.70 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing an extruded polystyrene resin foam board. [Background technology]

[0002] A conventional method for producing an extruded polystyrene resin foam board is known, in which a cell control agent is added to a base resin, the resulting mixture is heated and kneaded in an extruder, a physical blowing agent is then injected into the extruder and further kneaded, the resulting foamable molten resin composition is extruded from a high-pressure region to a low-pressure region (usually into the atmosphere), and the resulting foamable molten resin composition is shaped into a plate using a shaping device connected to the die outlet of the extruder. Extruded polystyrene resin foam boards have low thermal conductivity and excellent insulating properties, making them suitable for use as insulating materials for walls, floors, roofs, etc. of buildings.

[0003] A method for producing an extruded polystyrene resin foam board having heat insulating properties and flame retardancy has been proposed (for example, Patent Document 1). In the method for producing an extruded polystyrene resin foam board disclosed in Patent Document 1, a halogen-based flame retardant and a phosphorus-based flame retardant are added to an expandable molten resin composition to impart flame retardancy to the extruded foam board. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-331964 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in extruded polystyrene foam boards, heat resistance and manufacturing stability are sometimes required, and in order to reduce environmental impact and costs, it is sometimes required to reduce the amount of halogen-based flame retardants.

[0006] However, the method for producing an extruded polystyrene resin foam board disclosed in Patent Document 1 sometimes results in an extruded foam board having insufficient heat resistance, and when the amount of halogen-based flame retardant is reduced, the flame retardancy may be reduced.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing an extruded polystyrene resin foam board that can produce an extruded polystyrene foam board having desired flame retardancy and heat resistance and that can be produced with good production stability. [Means for solving the problem]

[0008] In order to solve the above problems, the following method for producing an extruded polystyrene resin foam board is provided.

[0009] [1] A foamable molten resin composition containing a base resin including a polystyrene resin, a flame retardant, and a physical foaming agent is extruded and foamed to form a plate using a molding tool. 3 More than 100kg / m 3 A method for producing the following extruded polystyrene resin foam board: The brominated flame retardant contains brominated styrene-butadiene copolymer. The phosphorus-based flame retardant comprises one or more metal phosphinates selected from the group consisting of metal salts of phosphinic acids, metal salts of diphosphinic acids, and mixtures thereof; the amount of the brominated styrene-butadiene copolymer added is 0.5 parts by mass or more and 12 parts by mass or less per 100 parts by mass of the base resin, A method for producing an extruded polystyrene resin foam board, wherein the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer is 0.05 or more and 0.70 or less. [2] The method for producing an extruded polystyrene resin foam board according to [1], wherein the phosphorus-based flame retardant has a melting point of 150°C or higher. [3] The method for producing an extruded polystyrene resin foam board according to [1] or [2], wherein the phosphorus content of the phosphorus-based flame retardant is 15% by mass or more. [4] The method for producing an extruded polystyrene resin foam board according to any one of [1] to [3], wherein the amount of the phosphorus-based flame retardant added is 0.15 parts by mass or more and 1 part by mass or less per 100 parts by mass of the base resin. [5] The method for producing an extruded polystyrene foam plate according to any one of [1] to [4], wherein the metal phosphinate includes an aluminum phosphinate. [6] The method for producing an extruded polystyrene foam plate according to any one of [1] to [5], wherein the extruded polystyrene foam plate has an average cell diameter in the thickness direction of 80 μm or more and 250 μm or less. [Effects of the Invention]

[0010] The method for producing an extruded polystyrene foam board of the present invention can produce an extruded foam board having the desired flame retardancy and heat resistance, and also ensures good production stability of the extruded foam board. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, one embodiment of the method for producing an extruded polystyrene resin foam board of the present invention will be described. The method for producing an extruded polystyrene resin foam board of the present invention includes the steps of extruding and foaming a foamable molten resin composition containing a base resin containing a polystyrene resin, a flame retardant, and a physical blowing agent, and molding the foam into a board using a molding tool. By this step, an extruded polystyrene resin foam board having an apparent density of 15 kg / m or more can be produced. 3 More than 100kg / m 3 The following extruded polystyrene resin foam board (hereinafter also referred to as extruded foam board) is produced.

[0012] Specifically, for example, a base resin, a flame retardant, and optional additives such as a cell regulator and a radiation suppressant are fed into an extruder, heated, melt-kneaded, and then a physical blowing agent is injected into the extruder and further kneaded to produce a foamable resin composition. This foamable resin composition is extruded from a high-pressure region to a low-pressure region (usually atmospheric) to foam it, and the resulting foam is shaped into a plate using a shaping device (such as a guider) connected to the die outlet of the extruder, thereby producing an extruded polystyrene resin foam plate. The shaping device may be, for example, a device consisting of a pair of upper and lower polytetrafluoroethylene plates.

[0013] <Base resin> The base resin contains a polystyrene resin as a main component. In this specification, "containing a polystyrene resin as a main component" means that the content of a specific component in 100% by mass of the composition is 50% by mass or more. Specifically, the content of the polystyrene resin in the base resin is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0014] (Polystyrene resin) The polystyrene resin is a polymer containing styrene as a main component, and a styrene homopolymer or a copolymer of styrene and a vinyl monomer copolymerizable with styrene can be used.

[0015] Specific examples of polystyrene resins include one or more selected from polystyrene, styrene-(meth)acrylic acid ester copolymers, styrene-(meth)acrylic acid copolymers, styrene-maleic anhydride copolymers, styrene-polyphenylene ether copolymers, styrene-acrylonitrile copolymers, styrene-methylstyrene copolymers, styrene-dimethylstyrene copolymers, styrene-ethylstyrene copolymers, styrene-diethylstyrene copolymers, etc. The term "(meth)acrylic acid" as used above is a concept that encompasses acrylic acid and methacrylic acid.

[0016] The content of the styrene component in the copolymer is preferably 50 mol % or more, more preferably 60 mol % or more, and even more preferably 70 mol % or more. The polystyrene resin may also contain polyfunctional monomer unit components such as divinylbenzene and multibranched macromonomers.

[0017] The polystyrene-based resin may be a biomass-derived polystyrene-based resin containing a biomass-derived monomer component. Note that the biomass-derived polystyrene-based resin may be one that has been certified by the mass balance method.

[0018] The polystyrene resin may also contain recycled components, such as commercially available recycled polystyrene resins and polystyrene resins obtained by reducing and pelletizing waste materials generated during the production of extruded polystyrene resin foam boards.

[0019] In addition, from the viewpoint of foaming property and manufacturing stability, the melt viscosity of polystyrene resin is set at 200°C and a shear rate of 100 sec -1 Under these conditions, the pressure is preferably 500 to 3000 Pa·s, more preferably 1000 to 2500 Pa·s, and even more preferably 1500 to 2300 Pa·s.

[0020] When the base resin contains a styrene-(meth)acrylic acid ester copolymer, a relatively large amount of hydrofluoroolefin (described below) as a physical blowing agent can be added, for example, at 0.5 mol / kg or more, resulting in an extruded foam board with superior thermal insulation properties. On the other hand, conventional extruded foam boards containing a styrene-(meth)acrylic acid ester copolymer as the main component tend to have reduced flame retardancy due to the (meth)acrylic acid ester component. In contrast, the present invention contains a specific flame retardant described below, so the resulting extruded foam board has excellent flame retardancy, even when the base resin contains a styrene-(meth)acrylic acid ester copolymer as the main component.

[0021] The styrene-(meth)acrylic acid ester copolymer is a copolymer of styrene and a lower alkyl (meth)acrylic acid ester, and specific examples thereof include a styrene-methyl acrylate copolymer, a styrene-ethyl acrylate copolymer, a styrene-propyl acrylate copolymer, a styrene-methyl methacrylate copolymer, a styrene-ethyl methacrylate copolymer, and a styrene-propyl methacrylate copolymer. Among these, the styrene-(meth)acrylic acid ester copolymer is preferably a styrene-methyl acrylate copolymer or a styrene-methyl methacrylate copolymer, and more preferably a styrene-methyl methacrylate copolymer. These styrene-(meth)acrylic acid ester copolymers can be used alone or in combination of two or more.

[0022] The content of the (meth)acrylic acid ester component in the styrene-(meth)acrylic acid ester copolymer can be, for example, in the range of 10% by mass or more and 80% by mass or less. Furthermore, from the viewpoint of ensuring flame retardancy, heat resistance, and production stability, it is preferable that the base resin contains a styrene-(meth)acrylic acid ester copolymer with a small amount of the (meth)acrylic acid ester component. In this case, the content of the (meth)acrylic acid ester component in the styrene-(meth)acrylic acid ester copolymer is preferably 5% by mass or more and less than 40% by mass, and more preferably 15% by mass or more and 30% by mass or less. The content of the (meth)acrylic acid ester component in the styrene-(meth)acrylic acid ester copolymer can be determined by a known method such as pyrolysis gas chromatography analysis.

[0023] (Other polymers) Polymers other than polystyrene-based resins may be added to the base resin as long as they do not impair the object of the present invention. Examples of other polymers include thermoplastic resins such as polyesters, polyolefins, and polyphenylene ethers, and thermoplastic elastomers such as styrene-based elastomers. The amount of polymers other than polystyrene-based resins added to the base resin (based on the base resin being 100% by mass) is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. It is most preferable that the amount is 0, i.e., the base resin contains only polystyrene-based resins as polymers.

[0024] (amorphous polyethylene terephthalate copolymer) Amorphous polyethylene terephthalate copolymers can be added to the base resin to further improve the thermal insulation, flame retardancy, and heat resistance of the extruded foam board. In this case, the amount of amorphous polyethylene terephthalate resin added to the base resin is preferably 5% to 40% by mass, more preferably 8% to 30% by mass. The heat of fusion associated with melting of the amorphous polyethylene terephthalate copolymer, as defined in JIS K7122 (1987), is less than 5 J / g. The heat of fusion is measured using a heat flux differential scanning calorimeter (HSC) based on the DSC curve obtained by heating a conditioned specimen at a heating rate of 10°C / min, as described in JIS K7122 (1987) for "measuring the heat of fusion after a certain heat treatment" (the heating and cooling rates for conditioning the specimen are both 10°C / min).

[0025] <Flame retardant> In the present invention, the flame retardant includes a predetermined brominated flame retardant and a phosphorus-based flame retardant. Specifically, the flame retardant includes a brominated styrene-butadiene copolymer as the brominated flame retardant and one or more metal phosphinates selected from the group consisting of metal salts of phosphinic acid, metal salts of diphosphinic acid, and mixtures thereof as the phosphorus-based flame retardant. By using the predetermined brominated flame retardant and phosphorus-based flame retardant in the predetermined amounts and mass ratios, an extruded foam board can be produced that exhibits excellent production stability and good flame retardancy and heat resistance. Furthermore, due to the synergistic effect of the predetermined brominated flame retardant and phosphorus-based flame retardant, high flame retardancy can be maintained even when the amount of the halogen-based flame-retardant brominated styrene-butadiene copolymer added is reduced within the range described below.

[0026] (Brominated flame retardants) The brominated flame retardant of the present invention includes a brominated styrene-butadiene copolymer. Examples of the brominated styrene-butadiene copolymer include one or more of a brominated styrene-butadiene block copolymer, a brominated styrene-butadiene random copolymer, and a brominated styrene-butadiene graft copolymer. Such a brominated styrene-butadiene copolymer is a polymer-type flame retardant produced, for example, by brominating a polystyrene-polybutadiene copolymer. Examples of the brominated styrene-butadiene copolymer preferably used in the present invention include commercially available products such as Emerald 3000 from Chemtura and FR122P from ICL-IP.

[0027] Considering dispersibility in polystyrene resins, the weight-average molecular weight of the brominated styrene-butadiene copolymer is preferably 100,000 to 200,000 in terms of polystyrene. From the viewpoint of flame retardancy, the bromine content is preferably 50 to 80 mass%. The bromine content can be determined based on JIS K7392 (2009).

[0028] The amount of brominated styrene-butadiene copolymer added is 0.5 to 12 parts by mass per 100 parts by mass of the base resin. By using the brominated styrene-butadiene copolymer in the above amount and in combination with a specific phosphorus-based flame retardant (described below) in a specific mass ratio, the flame retardancy, heat resistance, and manufacturing stability of the extruded foam board can be improved. Therefore, the brominated flame retardant added to the base resin preferably contains brominated styrene-butadiene copolymer as its main component. If only a brominated flame retardant other than brominated styrene-butadiene copolymer is used as the brominated flame retardant, the synergistic effect with the specific phosphorus-based flame retardant (described below) cannot be achieved, and reducing the amount of brominated flame retardant may result in a decrease in the flame retardancy of the extruded foam board. To achieve higher flame retardancy, the amount of the brominated styrene-butadiene copolymer added is preferably 1 part by mass or more, more preferably 2 parts by mass or more, particularly preferably 2.5 parts by mass or more, and most preferably 3 parts by mass or more, per 100 parts by mass of the base resin. To improve the manufacturing stability of the resulting extruded foam board, the amount of the brominated styrene-butadiene copolymer added is preferably 10 parts by mass or less, more preferably 9 parts by mass or less, per 100 parts by mass of the base resin.

[0029] In the present invention, the term "brominated flame retardant" refers to a material that contains bromine in its structure and exhibits flame retardant properties. Typically, brominated flame retardants exhibit flame retardancy by exhibiting radical trapping properties in the gas phase. In the present invention, the brominated flame retardant includes the above-mentioned brominated styrene-butadiene copolymer, but other brominated flame retardants may also be included within the scope of not impairing the intended effects of the present invention. Examples of other bromine-based flame retardants include tetrabromobisphenol A, tetrabromobisphenol-A-bis(2,3-dibromopropyl ether), tetrabromobisphenol-A-bis(2-bromoethyl ether), tetrabromobisphenol-A-bis(allyl ether), tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol S, tetrabromobisphenol-S-bis(2,3-dibromopropyl ether), hexabromocyclododecane, tetrabromocyclooctane, tris(2,3-dibromopropyl)isocyanurate, tribromophenol, decabromodiphenyl oxide, and tris(tribromoneopentyl)phosphate, and these may be used alone or in combination. The amount of other brominated flame retardants added is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, particularly preferably 1 part by mass or less, per 100 parts by mass of brominated styrene-butadiene copolymer, and most preferably 0, i.e., the brominated styrene-butadiene copolymer is the only brominated flame retardant included.

[0030] (phosphorus-based flame retardant) The phosphorus-based flame retardant in the present invention includes one or more phosphorus-based flame retardants selected from the group consisting of metal salts of phosphinic acid, metal salts of diphosphinic acid, and mixtures of metal salts of phosphinic acid and metal salts of diphosphinic acid. Hereinafter, the one or more phosphorus-based flame retardants selected from the group consisting of metal salts of phosphinic acid, metal salts of diphosphinic acid, and mixtures of metal salts of phosphinic acid and metal salts of diphosphinic acid may be referred to as metal phosphinic acid salts. The metal salts of phosphinic acid are represented by the following formula (I), and the metal salts of diphosphinic acid are represented by the following formula (II).

[0031] [ka] [ka]

[0032] In the above formula (I) and formula (II), R 1 and R 2 may be the same or different. 1 and R 2 are linear or branched alkyl and / or aryl having 1 to 6 carbon atoms. 3 is a linear or branched alkylene having 1 to 10 carbon atoms, an arylene having 6 to 10 carbon atoms, an alkylarylene having 6 to 10 carbon atoms, or an arylalkylene having 6 to 10 carbon atoms. In formula (I) and formula (II), M is a calcium ion, a magnesium ion, an aluminum ion, and / or a zinc ion. m is 2 or 3, n is 1 or 3, and x is 1 or 2.

[0033] The phosphorus-based flame retardant may be one type of compound represented by formula (I) or formula (II), or may contain two or more types of compounds, but preferably contains a metal phosphinate represented by formula (I). Specific examples of metal salts of phosphinate include calcium dimethylphosphinate, aluminum dimethylphosphinate, zinc dimethylphosphinate, calcium ethylmethylphosphinate, aluminum ethylmethylphosphinate, zinc ethylmethylphosphinate, calcium diethylphosphinate, aluminum diethylphosphinate, and zinc diethylphosphinate. Among these, it is more preferable that an aluminum salt of phosphinate is contained as the phosphorus-based flame retardant, and it is particularly preferable that aluminum diethylphosphinate is contained.

[0034] Furthermore, from the viewpoint of satisfactorily achieving the intended objectives of the present invention, the phosphorus-based flame retardant preferably contains, as a main component, one or more metal phosphinate salts selected from the group consisting of metal phosphinates, metal diphosphinates, and mixtures of metal phosphinates and metal diphosphinates, preferably an aluminum phosphinate salt, and more preferably aluminum diethylphosphinate. If only a phosphorus-based flame retardant other than the specified metal phosphinate salts is used as the phosphorus-based flame retardant, the synergistic effect with the specified brominated flame retardant is not achieved, and reducing the amount of brominated flame retardant may result in a decrease in the flame retardancy of the extruded foam board. Furthermore, the heat resistance of the extruded foam board may be insufficient.

[0035] Examples of phosphorus-based flame retardants containing metal phosphinate as the main component include the Exolit OP series manufactured by Clariant, and specific examples include commercially available grades such as OP1230, OP1240, OP1400, and OP1312.

[0036] From the viewpoint of more reliably increasing the flame retardancy of the extruded foam board, the phosphorus content of the phosphorus-based flame retardant is preferably 15% by mass or more and 30% by mass or less, more preferably 18% by mass or more and 28% by mass or less, and particularly preferably 20% by mass or more and 25% by mass or less, based on 100% by mass of the phosphorus-based flame retardant.

[0037] In the present invention, the phosphorus-based flame retardant refers to a material that contains phosphorus in its structure and exhibits flame retardant properties. Typically, phosphorus-based flame retardants exhibit flame retardancy by forming a char (carbonized layer) in the solid phase. In the present invention, the phosphorus-based flame retardant includes the above-mentioned metal phosphinate salts, but may also include other phosphorus-based flame retardants other than the above-mentioned metal phosphinate salts, as long as the intended effects of the present invention are not impaired. Examples of phosphorus-based flame retardants other than metal phosphinates include metal phosphates such as aluminum phosphate, triphenyl phosphate (TPP), triphenylphosphine oxide (TPPO), tricresyl phosphate (TCP), cresyl diphenyl phosphate (CDP), trixylenyl phosphate (TXP), xylyl diphenyl phosphate, resorcinol bis(diphenyl)phosphate, tris(chloroethyl)phosphate, tris(chloropropyl)phosphate (TCPP), and 2-diphenylphosphonylhydroquinone, and these may be used alone or in combination. The amount of phosphorus-based flame retardants other than the metal phosphinates is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less, per 100 parts by mass of the metal phosphinate. It is most preferred that the amount of the phosphorus-based flame retardant be 0, i.e., that the phosphorus-based flame retardant is solely composed of metal phosphinate.

[0038] The phosphorus-based flame retardant used in the present invention preferably has a melting point of 150°C or higher. In this case, the melting point of the phosphorus-based flame retardant is more preferably 160°C or higher, and even more preferably 165°C or higher, in order to further enhance the heat resistance of the resulting extruded foam board. The upper limit of the melting point of the phosphorus-based flame retardant is not particularly limited, but from the viewpoint of further improving production stability, 250°C can be used as a guideline, preferably 220°C, and more preferably 200°C. The melting point of the phosphorus-based flame retardant is determined in accordance with JIS K7121 (1987). Specifically, the conditioning method employs "(2) Measuring the melting temperature after a certain heat treatment." The conditioned test specimen is heated from 23°C to 280°C at a heating rate of 10°C / min to obtain a DSC curve, and the apex temperature of the melting peak is taken as the melting point. The heating and cooling rates during conditioning are 10°C / min. When multiple melting peaks appear on a DSC curve, the apex temperature of the melting peak with the largest area is taken as the melting point.

[0039] In the method for producing an extruded polystyrene resin foam board of the present invention, the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer is 0.05 or more and 0.70 or less. If the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer is less than 0.05, the flame retardancy of the extruded foam board may be reduced. To sufficiently enhance the flame retardancy of the extruded foam board, the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer is preferably 0.07 or more, more preferably 0.10 or more. On the other hand, if the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer exceeds 0.5, the resulting extruded foam board may shrink, resulting in reduced production stability. The reason why the extruded foam board tends to shrink when the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer is too high is unclear; however, it is thought that this may be due to localized aggregation of the metal phosphinate, which has a bubble nucleation effect, resulting in finer bubbles. To ensure stable production of extruded foam boards, the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer is preferably 0.45 or less, more preferably 0.40 or less. By setting the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer within the above range, even when a relatively large amount of the metal phosphinate, which has a bubble nucleation effect, is blended, the metal phosphinate can be adequately dispersed in the resin, and stable production of extruded foam boards is believed to be ensured.

[0040] From the viewpoint of ensuring that the flame retardancy, heat resistance, and manufacturing stability of the extruded foam board are improved, the amount of the phosphorus-based flame retardant added is preferably 0.10 parts by mass or more and 1.5 parts by mass or less, more preferably 0.15 parts by mass or more and 1 part by mass or less, and even more preferably 0.2 parts by mass or more and 0.8 parts by mass or less, per 100 parts by mass of the base resin.

[0041] In order to satisfy high flame retardancy such as the flammability standard for extruded polystyrene foam insulation described in "Test Method A" specified in the flammability test method of JIS A9521 (2022), the total amount of flame retardant added is preferably 1 to 15 parts by mass, and more preferably 2 to 12 parts by mass, per 100 parts by mass of the base resin.

[0042] (Other flame retardants and flame retardant assistants) Furthermore, in the present invention, in order to further improve the flame retardancy of the extruded foam board, other flame retardants or flame retardant assistants other than the bromine-based flame retardants and phosphorus-based flame retardants may be added in combination.

[0043] Examples of flame retardants other than bromine-based flame retardants and phosphorus-based flame retardants include polyalkylated aromatic compounds, hydrated metal compounds such as aluminum hydroxide and magnesium hydroxide, hindered amine compounds, etc. A flame retardant synergist is a type of compound that does not exhibit sufficient flame retardancy alone but exhibits a flame retardant effect when combined with another flame retardant, and examples thereof include diphenyl ethers such as poly-1,4-diisopropylbenzene, 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3,4-diethyl-3,4-diphenylhexane, 2,4-diphenyl-4-methyl-1-pentene, and 2,4-diphenyl-4-ethyl-1-pentene. Examples of suitable flame retardants include organic peroxides such as alkanes, diphenylalkenes, and dicumyl peroxide; nitrogen-containing cyclic compounds such as antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, melamine, melam, and melem; silicone compounds; inorganic compounds such as boron oxide, zinc borate, and zinc sulfide; and phosphorus compounds such as red phosphorus, ammonium polyphosphate, and phosphazene. When a flame retardant aid is added, the amount added is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the total amount of the flame retardants. From the perspective of further enhancing flame retardancy, it is preferable to include the above-mentioned other flame retardants and / or flame retardant aids in addition to the brominated styrene-butadiene copolymer and the metal phosphinate. In this case, the total amount of the other flame retardants and / or flame retardant synergists is preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 2 to 8 parts by mass, per 100 parts by mass of the brominated styrene-butadiene copolymer. This embodiment is more effective when the amount of the brominated styrene-butadiene copolymer added is relatively small, for example, 0.5 to 5 parts by mass, relative to the base resin. Furthermore, the other flame retardants and / or flame retardant synergists are preferably polyalkylated aromatic compounds such as poly-1,4-diisopropylbenzene.

[0044] An example of a method for adding a flame retardant to a thermoplastic resin containing a base resin is to supply a predetermined proportion of the flame retardant together with the thermoplastic resin to a raw material supply section provided upstream of the extruder and knead the flame retardant together with the thermoplastic resin in the extruder. Alternatively, the flame retardant can be supplied to a molten thermoplastic resin from a flame retardant supply section provided in the extruder. When supplying the flame retardant to the extruder, a method of supplying a dry blend of the flame retardant and the thermoplastic resin to the extruder, a method of supplying a liquid flame retardant that has been preheated and melted into the extruder, or a method of preparing a masterbatch containing the flame retardant and a thermoplastic resin as a base resin and supplying it to the extruder can be used. In particular, from the viewpoint of dispersibility, it is preferable to prepare a masterbatch containing the flame retardant and supply it to the extruder. When using a method of preparing a masterbatch containing the flame retardant and supplying it to the extruder, the brominated styrene-butadiene copolymer and the phosphorus-based flame retardant may be blended in the same masterbatch and supplied, or they may be supplied as separate masterbatches. The same applies to the blending method of the flame retardant aid.

[0045] (physical foaming agent) The physical blowing agent preferably has zero or extremely low ozone depletion potential and low global warming potential. For the purpose of reducing the thermal conductivity of the extruded polystyrene resin foam board, it is preferable to use one or more physical blowing agents selected from the group consisting of saturated hydrocarbons having at least 3 to 5 carbon atoms and hydrofluoroolefins (HFOs).

[0046] Specific examples of saturated hydrocarbons having 3 to 5 carbon atoms include propane, butane, and pentane. These blowing agents can be used alone or in combination of two or more. The saturated hydrocarbons having 3 to 5 carbon atoms have an ozone depletion potential of zero, a very low global warming potential, and low thermal conductivity in a gaseous state.

[0047] Specific examples of hydrofluoroolefins include 1,3,3,3-tetrafluoropropene (hereinafter also referred to as HFO1234ze), 1-chloro-3,3,3-trifluoropropene (hereinafter also referred to as HFO1233zd), 1-chloro-2,3,3,3-tetrafluoropropene (hereinafter also referred to as HFO1224yd), 2,3,3,3-tetrafluoropropene (HFO-1234yf), and 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz). These blowing agents can be used alone or in combination of two or more. The hydrofluoroolefins have an ozone depletion potential of zero, an extremely low global warming potential, low thermal conductivity in the gaseous state, and are non-flammable.

[0048] Among the hydrofluoroolefins, from the viewpoint of obtaining an extruded foam board with particularly low thermal conductivity, it is preferable to use one or more selected from HFO1234ze, HFO1233zd, HFO1224yd, and HFO-1336mzz. From the viewpoint of further improving the production stability of the obtained extruded foam board and further improving the long-term heat insulation properties, it is preferable to use a combination of HFO1234ze and HFO1233zd as the hydrofluoroolefin.

[0049] The amount of hydrofluoroolefin added is preferably 0.1 mol or more and 1.5 mol or less per 1 kg of base resin. When the amount of hydrofluoroolefin added is within this range, the extruded foam board has good production stability, and an effective amount of hydrofluoroolefin remains in the foamed insulation board after extrusion foaming, resulting in an extruded foam board with long-term insulation properties. From this perspective, the amount of hydrofluoroolefin added is more preferably 0.05 mol or more and 1.5 mol or less per 1 kg of base resin, more preferably 0.1 mol or more and 1.0 mol or less, and even more preferably 0.2 mol or more and 0.6 mol or less. In particular, when a styrene-(meth)acrylic acid ester copolymer is included as the main component of the base resin, good production stability can be ensured even when a relatively large amount of hydrofluoroolefin, for example, 0.5 mol / kg or more, is added.

[0050] Examples of physical blowing agents other than saturated hydrocarbons having 3 to 5 carbon atoms and hydrofluoroolefins include aliphatic alcohols having 1 to 5 carbon atoms, water, dialkyl ethers having an alkyl chain with 1 to 3 carbon atoms, and carbon dioxide. A preferred example of the aliphatic alcohols having 1 to 5 carbon atoms is ethanol. A preferred example of the dialkyl ethers having an alkyl chain with 1 to 3 carbon atoms is dimethyl ether.

[0051] In particular, from the viewpoint of achieving high early dissipation properties, enabling early stabilization of the shape of extruded foam boards, and the consistent production of extruded foam boards with lower apparent densities when used in combination with saturated hydrocarbons and / or hydrofluoroolefins having 3 to 5 carbon atoms, water and / or alcohol are preferred as physical blowing agents, and the use of both water and alcohol is even more preferred. The amount of water and / or alcohol added is preferably 0.01 mol to 0.6 mol, more preferably 0.1 mol to 0.5 mol, per 1 kg of base resin. The amount of water and / or alcohol added refers to the amount added when only water or alcohol is used, and refers to the total amount added when both water and alcohol are used. To ensure the above-mentioned effects, it is preferable to use both water and alcohol and keep the total amount added within the above range. There are no limitations on the blend ratio of the two, but a water:alcohol ratio of 90 mol%:10 mol% to 50 mol%:50 mol% is preferred, and 80 mol%:20 mol% to 60 mol%:40 mol% is more preferred.

[0052] Dimethyl ether is preferably used as the physical blowing agent because it has high compatibility with polystyrene resins and, when used in combination with hydrofluoroolefins, it is easy to obtain lightweight extruded foam boards with good appearance. The amount of dimethyl ether added is preferably 0.05 mol or more and 0.5 mol or less, and more preferably 0.1 mol or more and 0.4 mol or less, per kg of base resin.

[0053] (Radiation suppressant) The heat insulating properties can be further improved by adding a radiation inhibitor to the base resin. Examples of radiation inhibitors include graphite, metal oxides such as titanium oxide, metals such as aluminum, ceramics, carbon black, infrared-shielding pigments, hydrotalcite, etc. One or more of these can be used. Of these, graphite is preferred as the radiation inhibitor. Examples of graphite include flake graphite, flaky graphite, artificial graphite, and earthy graphite, and it is preferred to use one whose main component is flake graphite.

[0054] The amount of the radiation suppressor added is, for example, in the range of 0.2 to 8 parts by mass, preferably 0.5 to 6 parts by mass, per 100 parts by mass of the base resin. When the base resin contains graphite as the radiation suppressor, the content of graphite in the foamable melt resin composition is preferably 0.2 to 8.0 parts by mass, more preferably 0.3 to 5.0 parts by mass, per 100 parts by mass of the base resin.

[0055] (Other additives) In the present invention, various additives such as cell regulators, colorants such as pigments and dyes, heat stabilizers, weathering agents, antibacterial agents, and fillers may be added to the base resin as needed.

[0056] Examples of suitable cell regulators include inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, aluminum oxide, clay, bentonite, and diatomaceous earth, as well as conventional chemical foaming agents such as azodicarbodiamide. Among these, talc is preferred because it does not impair flame retardancy and allows for easy cell size control. Talc with a particle size of 0.1 to 20 μm, and more preferably 0.5 to 15 μm, as defined in JIS Z8901 (2006) is particularly preferred. The amount of cell regulator added varies depending on the type of cell regulator, the desired cell size, and other factors, but is generally 0.01 to 5 parts by weight, preferably 0.05 to 4 parts by weight, and particularly preferably 0.1 to 3 parts by weight, per 100 parts by weight of the base resin.

[0057] The physical properties of the extruded foam board will be described in detail below.

[0058] [Apparent Density] The apparent density of the extruded foam board of the present invention is 15 kg / m 3 More than 100kg / m 3 In order to improve the manufacturing stability and mechanical strength of the foamed board, the lower limit is 20 kg / m 3 It is preferable that the 3 From the viewpoint of improving the heat insulating property and ensuring the light weight, the upper limit is 80 kg / m 3 Preferably, it is 60 kg / m 3 More preferably, it is 50 kg / m 3 More preferably, it is 45 kg / m 3 The apparent density of the extruded foam board can be measured in accordance with JIS K6767 (1999).

[0059] Thickness The thickness of the extruded foam board is appropriately set depending on the intended use and is not particularly limited, but from the viewpoint of use as a heat insulating material, it is preferably 10 mm or more, more preferably 25 mm or more, even more preferably 35 mm or more, and particularly preferably 45 mm or more, with the upper limit of the thickness being approximately 150 mm.

[0060] [width] The width of the extruded foam plate is also appropriately set depending on the intended use, and is not particularly limited, but is preferably 300 mm or more and 2000 mm or less. The width of the extruded foam plate refers to the length in the width direction (the direction perpendicular to the extrusion direction and the thickness direction) of the foam plate when the foamable molten resin composition is extruded and foamed and molded into a plate using a molding tool.

[0061] [Average bubble diameter in thickness direction] The average cell diameter in the thickness direction (VD direction) of the extruded foam board is preferably 80 μm or more and 250 μm or less, more preferably 90 to 220 μm, and even more preferably 100 to 200 μm. By having the average cell diameter within this range, the extruded foam board has even higher heat insulating properties and superior mechanical strength. Furthermore, shrinkage immediately after production is suppressed, further improving production stability.

[0062] [Closed bubble rate] From the viewpoint of long-term heat insulation, the closed cell content of the extruded foam board is preferably 85% or more, more preferably 90% or more, and even more preferably 92% or more. The closed cell content of extruded foam boards was measured by cutting samples from five randomly selected locations on the extruded foam board. The closed cell content of each sample was calculated, and the arithmetic mean value of the closed cell content of the five locations was used. The cut samples were skinless samples cut from the extruded foam board to dimensions of 45 mm x 20 mm x 25 mm. If the extruded foam board was too thin to cut a 25 mm sample, two cut samples (45 mm x 20 mm x 12.5 mm) were stacked on top of each other for measurement. The closed cell content (S) (%) was calculated using the true volume (Vx) of the extruded polystyrene foam board measured using an air-comparison hydrometer (e.g., Toshiba Beckman, Model 930) according to Procedure C of ASTM-D2856-70, using the following formula (1): S(%)=(Vx-W / ρ)×100 / (VA-W / ρ)···(1) Vx: The true volume (cm) of the cut sample determined by measurement using an air comparison hydrometer 3 ) (This corresponds to the sum of the volume of the resin that makes up a cut sample of the foam and the total volume of the air bubbles in the closed cell portion of the cut sample.) VA: Apparent volume (cm) of the cut sample calculated from the outer dimensions of the cut sample used for measurement 3 ) W: Total weight of the cut sample used for measurement (g) ρ: Density of the base resin constituting the extruded polystyrene resin foam board (g / cm 3 )

[0063] [Heat resistance (rate of dimensional change due to heating)] The dimensional change rate upon heating of the extruded foam board when heated in an 80°C atmosphere for 22 hours is within 10%. If the dimensional change rate at 80°C is within this range, the extruded foam board has high heat resistance, and for example, even when placed flat under the summer sun, the dimensions are unlikely to change. The dimensional change rate upon heating refers to the rate of change in dimensions due to shrinkage and expansion caused by heating. Specific measurement methods will be explained in the examples.

[0064] The method for producing an extruded polystyrene resin foam board of the present invention is not limited to the above-described embodiment. [Example]

[0065] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples in any way.

[0066] In the examples and comparative examples, extruded foam boards were produced using the following extrusion equipment and raw materials. <Extrusion equipment> An extrusion device was used in which a first extruder with an inner diameter of 180 mm and a second extruder with an inner diameter of 225 mm were connected in series, a physical foaming agent injection port was provided near the end of the first extruder, and a flat die with a resin discharge port (die lip) with a rectangular cross section and a gap of 2.5 mm and a width of 400 mm or 1000 mm was connected to the outlet of the second extruder. A shaping device (guider) consisting of a pair of upper and lower polytetrafluoroethylene resin plates was attached to the resin outlet of the flat die so that the upper and lower resin plates were parallel to each other.

[0067] The base resins, cell regulators, flame retardants and physical foaming agents used in the examples and comparative examples are shown below. <Base resin> PS: GPPS, manufactured by DIC, HP600ANJ, melt viscosity (200°C, 100 sec -1), 1420 Pa·s SPET: amorphous polyethylene terephthalate copolymer (ethylene glycol / spiroglycol = 70 mol% / 30 mol%) ALTESTER30 (manufactured by Mitsubishi Gas Chemical Company, Inc.) MS200: Styrene-methyl methacrylate copolymer, manufactured by Toyo Styrene Co., Ltd., MS200 M component - 20% by mass, styrene component - 80% by mass, melt viscosity (200°C, 100 sec -1 )1980 Pa·s

[0068] <Foam adjuster> Talc: Matsumura Sangyo Co., Ltd. "Hi Filler #12" <Radiation suppressant> Graphite: Nippon Graphite Industries Co., Ltd. "CP-N", flake graphite

[0069] <Flame retardant> (Brominated flame retardants) FR(B)1: A mixture of brominated butadiene-styrene block copolymer (Emerald Innovation 3000) manufactured by Lanxess KK and poly-1,4-diisopropylbenzene (CCPIB) manufactured by United Initiators (where the mass ratio of Emerald Innovation 3000 to CCPIB is 20:1). FR(B)2: Brominated butadiene-styrene block copolymer: "Emerald innovation 3000" manufactured by LANXESS KK FR(B)3: A flame retardant masterbatch (GR-134BG manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) containing a 60% by mass mixture of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether): Daiichi Kogyo Seiyaku "SR-130" and tetrabromobisphenol A-bis(2,3-dibromopropyl ether): Daiichi Kogyo Seiyaku "SR-720" (60% by mass / 40% by mass). (phosphorus-based flame retardant) FR(P)1: Aluminum phosphinate, melting point 170°C, phosphorus content 23%, Clariant Exolit OP1230 FR(P)2: Aluminum phosphinate, melting point 170°C, phosphorus content 23%, Clariant Exolit OP1240 (PET decomposition inhibitor grade) FR(P)3: Triphenyl phosphate, melting point 50°C, phosphorus content 9.5%, manufactured by Daihachi Chemical Industry Co., Ltd. FR(P)4: Triphenylphosphine oxide, melting point 157°C, phosphorus content 11.0%, manufactured by Hokko Chemical Industry Co., Ltd. FR(P)5: Aromatic condensed phosphate ester, melting point 95°C, phosphorus content 9.0%, PX-200 manufactured by Daihachi Chemical Industry Co., Ltd. FR(P)6: PHOPHAL manufactured by Kanto Chemical Co., Ltd., aluminum phosphate, melting point 1500°C, phosphorus content 33%

[0070] <Physical foaming agent> 1,3,3,3-Tetrafluoropropene (HFO-1234ze) 1-chloro-3,3,3-trifluoropropene (HFO-1233zd) Isobutane (i-Bu) Dimethyl ether (DME) Carbon dioxide (CO2) Ethanol (EtOH) water

[0071] The base resin, cell control agent, and flame retardant were each fed into an extruder in the proportions shown in Tables 1 to 4 and melt-kneaded. The physical blowing agents shown in Tables 1 to 4 were then fed through the physical blowing agent inlet and further melt-kneaded. The molten mixture was extruded through a die lip at the tip of the extruder under atmospheric pressure and molded into a 55-mm-thick plate (base plate) shown in Tables 1 to 4 using a shaping device (guider). The molding skins on both sides were then uniformly trimmed to a thickness of 50 mm to produce the extruded polystyrene resin foam plates of Examples 1 to 14 and Comparative Examples 1 to 10. In Example 14, a mixture of 80% by weight of OP1230 and 20% by weight of PHOPHAL (the total amount of both was 100% by weight) was used as the phosphorus-based flame retardant.

[0072] The extruded foam boards were measured for apparent density, closed cell content, average cell diameter, flame retardancy, manufacturing stability (shrinkage, surface properties), LOI (oxygen index), and heat resistance (rate of dimensional change upon heating) using the following methods.

[0073] <Apparent density> The apparent density was measured in accordance with JIS K6767 (1999). Rectangular samples measuring 50 mm long, 50 mm wide, and 50 mm thick were cut from each extruded foam plate at three locations: the center and both ends in the width direction. The apparent density of each sample was measured, and the arithmetic mean of the measurements at the three locations was used as the apparent density.

[0074] <Closed bubble rate> The closed cell content of extruded foam boards was measured by cutting samples from five randomly selected locations on the extruded foam board. The closed cell content of each sample was calculated, and the arithmetic mean value of the closed cell content of the five locations was used. The cut samples were skinless samples cut from the extruded foam board to dimensions of 45 mm x 20 mm x 25 mm. If the extruded foam board was too thin to cut a 25 mm sample, for example, two cut samples (45 mm x 20 mm x 12.5 mm) were stacked together for measurement. The closed cell content (S) (%) was calculated using the true volume (Vx) of the extruded polystyrene resin foam board measured using an air-comparison hydrometer (Toshiba Beckman Corporation, Model 930) according to Procedure C of ASTM-D2856-70, using the following formula (1): S(%)=(Vx-W / ρ)×100 / (VA-W / ρ)···(1) Vx: The true volume (cm) of the cut sample determined by measurement using an air comparison hydrometer 3 ) (This corresponds to the sum of the volume of the resin that makes up a cut sample of the foam and the total volume of the air bubbles in the closed cell portion of the cut sample.) VA: Apparent volume (cm) of the cut sample calculated from the outer dimensions of the cut sample used for measurement 3 ) W: Total weight of the cut sample used for measurement (g) ρ: Density (g / cm³) of the base resin constituting the polystyrene-based resin extruded foam board 3 )

[0075] <Average cell diameter in the thickness direction> The average cell diameter in the thickness direction was obtained by obtaining magnified photographs in which the magnification was adjusted within the range of about 50 to 200 times so that the number of cells in the photograph was about 200 to 500 at three locations, namely, the central part and the vicinity of both ends in the vertical cross-section in the width direction of the extruded foam board. On each photograph, the maximum diameter in the thickness direction of each cell was measured using the image processing software NS2K-pro manufactured by Nanosystem Co., Ltd., and the arithmetic mean of those values was calculated. The average cell diameter in the thickness direction is also referred to as the VD cell diameter.

[0076] <Flame retardancy (JIS self-extinguishing property)> After production, for the extruded foam board after 7 days in an atmosphere of temperature 23°C and humidity 50%, a flammability test was conducted in accordance with Measurement Method A of the flammability test method of JIS A9521 (2022). For measurement, 5 test pieces were randomly cut out from one extruded foam board, and the flame retardancy was evaluated according to the following criteria. 〇: The average extinguishing time of the 5 test pieces is within 3 seconds, there is no remaining dust, and it does not burn beyond the combustion limit line. ×: The average combustion time of the 5 test pieces exceeds 3 seconds.

[0077] <LOI (Oxygen index)> After leaving the extruded foam board immediately after production in an atmosphere of temperature 23°C and humidity 50% for 4 weeks, test pieces were cut out from the extruded foam board, measured in accordance with JIS K7201 (2007), and the flame retardancy was evaluated. The type of heat source of the igniter was liquefied petroleum gas (LPG), the ignition procedure was Method A, and the test pieces were made to stand independently at a predetermined position in the testing machine. The test was conducted at a temperature of 23°C and a humidity of 50% at the test site.

[0078] <Overall evaluation of flame retardancy> The overall evaluation of flame retardancy was evaluated according to the following criteria. 〇 (Good): (JIS self-extinguishing property is "〇" and oxygen index is 26 or more) × (Poor): (JIS self-extinguishing property is "×" and / or oxygen index is less than 26)

[0079] <Manufacturing stability (shrinkage, surface properties)> The manufacturing stability (shrinkage, surface properties) was evaluated according to the following criteria. The state of shrinkage and the surface state of the original plate before cutting the molded skin and the extruded foam plate after cutting the molded skin were visually observed and evaluated as follows. ⊚: The shrinkage state and surface condition of the original plate and extruded foam plate were extremely good. ◯: The shrinkage state of the base plate and the extruded foam plate was extremely good, and although cracks and tears occurred on the surface of the base plate, the surface of the extruded foam plate was in extremely good condition. ×: The original plate shrank significantly, and good extruded foam plates could not be obtained stably.

[0080] <Heat resistance (rate of dimensional change due to heating)> The 80°C dimensional change rate of each sample in the thickness, length, and width directions was measured as follows. First, a foam board was bisected parallel to the length and at the center in the width direction. A rectangular parallelepiped test piece measuring 100 mm in length (vertical), 100 mm in width (horizontal), and 50 mm in thickness was cut from the center, including the surface exposed by the bisection. This test piece was then left at 23°C for at least one day, and the thickness, length, and width dimensions of each part of the test piece were measured with a vernier caliper. Next, the test piece after dimension measurement was heated in an oven adjusted to an 80°C atmosphere for 22 hours. After leaving the heated test piece at 23°C for one day, the dimensions were measured at the same locations as before heating, and the dimensional change rates in the thickness, length, and width directions before and after heating were calculated using the following formulas. Dimensional change rate = (1 - [test piece dimensions after heating / test piece dimensions before heating]) x 100 The above procedure was performed on three test pieces, and the arithmetic mean of the dimensional changes in the thickness, length, and width directions was taken as the dimensional change upon heating. The heat resistance of the extruded foam board was evaluated based on the calculated dimensional change upon heating (%) of the extruded foam board according to the following criteria. ◯ (Good): The rate of dimensional change upon heating is 10% or less. × (bad): The rate of dimensional change due to heating exceeds 10%. The results are shown in Tables 1 to 4.

[0081] [Table 1]

[0082] [Table 2]

[0083] [Table 3]

[0084] [Table 4]

[0085] The extruded foam boards of Examples 1 to 14 and Comparative Examples 2 and 3 contained a brominated styrene-butadiene copolymer as a brominated flame retardant and a metal phosphinate as a phosphorus-based flame retardant. Examining the above examples and comparative examples, the extruded foam boards of Examples 1 to 14 achieved excellent results in all categories, whereas Comparative Example 2, in which the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer was lower than the range specified in the present invention, had a poor flame retardancy rating. Comparative Example 3, in which the mass ratio was higher, showed significant shrinkage and poor manufacturing stability. It was confirmed that the extruded foam board of Comparative Example 3 had a smaller average cell diameter.

[0086] Furthermore, Comparative Example 1, which used only a brominated flame retardant containing a brominated styrene-butadiene copolymer as the flame retardant, had inferior flame retardancy compared to Examples (e.g., Examples 1 to 4) in which the same amount of brominated styrene-butadiene copolymer as Comparative Example 1 or a smaller amount of brominated styrene-butadiene copolymer was used in combination with a metal phosphinate in a predetermined ratio. In other words, simply reducing the amount of halogen-based flame retardant (brominated styrene-butadiene copolymer) made it difficult to ensure flame retardancy. Comparative Example 9, which used only a brominated flame retardant containing a brominated styrene-butadiene copolymer as the flame retardant and incorporated a large amount of radiation suppressant, also had inferior flame retardancy compared to Example 13 in which the same amount of brominated styrene-butadiene copolymer as Comparative Example 9 was used in combination with a metal phosphinate in a predetermined ratio.

[0087] In addition, for the extruded foam boards of Comparative Examples 4 to 6 and 8, which used a phosphate ester-based flame retardant other than a metal phosphinate as the phosphorus-based flame retardant, Comparative Examples 5, 6 and 8 had poor flame retardancy, and the synergistic effect with the brominated styrene-butadiene copolymer was insufficient. Therefore, it was not possible to reduce the amount of halogen-based flame retardant. Comparative Example 4, in which the amount of phosphate ester-based flame retardant added was increased to improve flame retardancy in Comparative Example 8, resulted in poor heat resistance.

[0088] Furthermore, the extruded foam board of Comparative Example 7, in which a brominated flame retardant other than a brominated styrene-butadiene copolymer was used in combination with a metal phosphinate, exhibited poor flame retardancy, and no synergistic effect with the metal phosphinate was observed compared with Comparative Example 10. Therefore, it was not possible to reduce the amount of halogen-based flame retardant.

Claims

1. The method includes a step of extruding and foaming a foamable molten resin composition containing a base resin including a polystyrene-based resin, a flame retardant, and a physical foaming agent, and molding the extrudate into a plate using a molding tool. ３ More than 100kg / m ３ A method for producing the following extruded polystyrene resin foam board: The brominated flame retardant contains a brominated styrene-butadiene copolymer, The phosphorus-based flame retardant comprises one or more metal phosphinates selected from the group consisting of metal salts of phosphinic acids, metal salts of diphosphinic acids, and mixtures thereof; the amount of the brominated styrene-butadiene copolymer added is 0.5 parts by mass or more and 12 parts by mass or less per 100 parts by mass of the base resin, The method for producing an extruded polystyrene resin foam board, wherein the mass ratio of the metal phosphinate to the brominated styrene-butadiene copolymer is 0.05 or more and 0.70 or less.

2. 2. The method for producing an extruded polystyrene resin foam board according to claim 1, wherein the phosphorus-based flame retardant has a melting point of 150°C or higher.

3. 3. The method for producing an extruded polystyrene resin foam board according to claim 1, wherein the phosphorus-based flame retardant has a phosphorus content of 15% by mass or more.

4. 3. The method for producing an extruded polystyrene resin foam board according to claim 1, wherein the phosphorus-based flame retardant is added in an amount of 0.15 parts by mass or more and 1 part by mass or less per 100 parts by mass of the base resin.

5. The method for producing an extruded polystyrene resin foam board according to claim 1 or 2, wherein the metal phosphinate comprises an aluminum phosphinate.

6. 3. The method for producing an extruded polystyrene resin foam board according to claim 1, wherein the extruded polystyrene resin foam board has an average cell diameter in the thickness direction of 80 μm or more and 250 μm or less.

Images