Extruded styrene resin foam and method for producing same

Abstract

To provide an extruded styrenic resin foam that achieves improved flame retardancy and reduced variations in average combustion time in accordance with JIS.SOLUTION: An extruded styrenic resin foam includes a styrenic resin, and a brominated flame retardant and an anion surfactant. The content of the anion surfactant is 0.01-5.0 pts.wt. relative to 100 pts.wt. of the styrenic resin. The brominated flame retardant is a brominated styrene butadiene polymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an extruded styrene resin foam having flame retardant properties and a method for producing the same. [Background technology]

[0002] A method for continuously producing a styrene resin foam by heating and melting a styrene resin in an extruder or the like, adding a blowing agent, cooling the mixture, and extruding the mixture into a low-pressure region is already known. A flame retardant is added to the extruded styrene resin foam in order to satisfy the flammability standard for extruded styrene foam insulation boards specified in JIS A9511. The main required property of a flame retardant suitable for extruded styrene resin foam is that it does not decompose at temperatures of around 230°C, which are the extrusion processing conditions for typical styrene resins. If the flame retardant decomposes under extrusion processing conditions, it will cause deterioration of the resin, which will have adverse effects such as worsening the moldability of the resulting foam and making it difficult to control the foam cell diameter. Another necessary characteristic of flame retardants suitable for extruded styrene resin foams is that they decompose efficiently before the decomposition of the styrene resin. Polystyrene is known to decompose at temperatures around 300°C. Therefore, if the flame retardant does not decompose efficiently at temperatures below 300°C, it may not meet the flammability standards set forth in JIS A9511. Furthermore, in order to achieve the required combustion performance, it is necessary to add a large amount of flame retardant, which tends to have adverse effects such as increased product costs and poor moldability of the resulting foam.

[0003] Given the above background, hexabromocyclodecane (hereinafter abbreviated as "HBCD") has been widely used as a flame retardant for extruded styrene resin foams. HBCD is known to be relatively stable under extrusion processing conditions and to decompose efficiently when polystyrene is decomposed, and it can exhibit high flame retardancy with a small amount added. However, HBCD is a persistent and bioaccumulative compound, which is undesirable from an environmental hygiene perspective, and there is a need to reduce the amount of HBCD used and to develop flame retardants to replace HBCD. Therefore, studies are being conducted on extruded styrene resin foams using brominated flame retardants other than HBCD.

[0004] For example, polymer flame retardants have been developed to replace conventional low-molecular-weight flame retardants as an alternative to HBCD. Among these, brominated styrene-butadiene block copolymers have attracted attention as having flame retardant performance at the same level as HBCD (see Patent Documents 1 and 2). However, brominated styrene-butadiene block copolymers have problems with thermal stability, and a technology has been disclosed in which the thermal stability of brominated polymer flame retardants is improved by using alkyl phosphite and epoxy compounds as stabilizers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-120935 [Patent Document 2] Japanese Patent Application Publication No. 2017-2248 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the above-mentioned conventional technology, there was a large variation in the measured values ​​in the JIS A9511 combustion test, and there was a risk that the JIS flammability standard would not be met. The present invention has been made to solve the above-mentioned problems associated with flame-retardant extruded styrene resin foams, and an object of the present invention is to provide an extruded styrene resin foam having excellent flame retardancy. [Means for solving the problem]

[0007] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by adding an aliphatic bromine-containing polymer as a flame retardant and a predetermined amount of alkyl sulfate as an anionic surfactant to a styrene-based resin foam obtained by melt-kneading a styrene-based resin and a blowing agent in an extruder and extruding and foaming the resulting mixture under a low pressure.

[0008] That is, the present invention is [1] An extruded styrene-based resin foam containing a styrene-based resin, a brominated flame retardant, and an anionic surfactant, wherein the brominated flame retardant is a brominated styrene-butadiene polymer. [2] The extruded styrene-based resin foam according to [1], characterized in that it contains 0.5 to 3.0 parts by weight of a brominated styrene-butadiene polymer per 100 parts by weight of the total amount of the styrene-based resin. [3] The extruded styrene-based resin foam according to [1] or [2], characterized in that the anionic surfactant is contained in an amount of 0.01 to 0.1 parts by weight per 100 parts by weight of the total amount of the styrene-based resin. [4] The extruded styrene resin foam according to any one of [1] to [3], wherein the anionic surfactant is an alkyl sulfate. [5] The extruded styrene-based resin foam according to any one of [1] to [4], further comprising a radical generator, the radical generator being contained in an amount of 0.05 to 0.5 parts by weight per 100 parts by weight of the total amount of the styrene-based resin. [6] The extruded styrene resin foam according to [5], wherein the radical generator is 2,3-dimethyl-2,3-diphenylbutane and / or poly-1,4-diisopropylbenzene. [7] The extruded styrene resin foam according to any one of [1] to [6], which passes the combustion test method of JIS A9511. [8] The extruded styrene resin foam according to any one of [1] to [7], characterized in that the extruded styrene resin foam has an average combustion time of less than 1.0 second and a standard deviation of less than 0.3 in a combustion test according to JIS A9511. [9] The extruded styrene resin foam board according to any one of [1] to [8], wherein the extruded styrene resin foam is an extruded styrene resin foam board.

[10] A method for producing an extruded foam by extruding and foaming a styrene-based resin composition containing a styrene-based resin, a brominated flame retardant, and an anionic surfactant, wherein the brominated flame retardant is a brominated styrene-butadiene polymer.

[11] A method for producing the extruded styrene resin foam according to

[10] , comprising a step of mixing a styrene resin with an anionic surfactant.

[12] The method for producing an extruded styrene resin foam according to

[10] or

[11] , wherein the blowing agent is at least one selected from saturated hydrocarbons having 3 to 5 carbon atoms.

[13] The method for producing an extruded styrene resin foam according to

[12] , further comprising, as a blowing agent, at least one selected from the group consisting of water, carbon dioxide, nitrogen, alcohols having 1 to 4 carbon atoms, dimethyl ether, methyl chloride, and ethyl chloride. [Effects of the Invention]

[0009] The extruded styrene resin foam of the present invention is an extruded styrene resin foam with improved flame retardancy and reduced variation in the average time for JIS flammability. DETAILED DESCRIPTION OF THE INVENTION

[0010] One embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, the term "A to B" representing a numerical range means "greater than or equal to A (including and greater than A) and less than or equal to B (including and less than B)."

[0011] (styrene resin) The styrene-based resin used in the present invention is not particularly limited as long as it is a styrene-based resin different from the brominated styrene-butadiene polymer described below, and examples thereof include homopolymers of styrene-based monomers such as styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, bromostyrene, chlorostyrene, vinyltoluene, and vinylxylene, and copolymers composed of a combination of two or more types of monomers; and copolymers obtained by copolymerizing the above-mentioned styrene-based monomers with at least one monomer such as divinylbenzene, butadiene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, maleic anhydride, and itaconic anhydride. The monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, maleic anhydride, and itaconic anhydride that are copolymerized with the styrene-based monomer can be used in an amount that does not decrease the physical properties such as compressive strength of the extruded styrene-based resin foam to be produced.

[0012] Furthermore, the styrene-based resin used in the present invention is not limited to a homopolymer or copolymer of the styrene-based monomer, but may be a blend of a homopolymer or copolymer of the styrene-based monomer with a homopolymer or copolymer of the other monomer, or may be a blend of diene rubber-reinforced polystyrene or acrylic rubber-reinforced polystyrene. Among these styrene-based resins, styrene homopolymer, styrene-acrylonitrile copolymer, (meth)acrylic acid copolymerized polystyrene, maleic anhydride-modified polystyrene, and impact-resistant polystyrene are preferred from the viewpoint of extrusion foam moldability, etc. Styrene homopolymer is particularly preferred from the viewpoint of cost.

[0013] The styrene-based resin preferably contains 50 parts by weight or more, more preferably 60 parts by weight or more, even more preferably 70 parts by weight or more, still more preferably 80 parts by weight or more, even more preferably 90 parts by weight or more, and particularly preferably 95 parts by weight or more of a resin having a structural unit derived from a styrene-based monomer, per 100 parts by weight of the styrene-based resin.

[0014] (Flame retardant) In the extruded styrene-based resin foam of the present invention, a brominated styrene-butadiene polymer is used as the brominated flame retardant, thereby making it possible to obtain a foam having excellent flame retardancy and environmental compatibility. Examples of the brominated styrene-butadiene polymer used in the present invention include brominated styrene-butadiene block copolymers, brominated styrene-butadiene random copolymers, brominated styrene-butadiene graft polymers, and brominated-epoxidized styrene-butadiene block copolymers. These may be used alone or in combination of two or more. Among these, brominated styrene-butadiene block copolymers are preferred in terms of performance, cost, and stable supply.

[0015] Examples of such brominated styrene-butadiene polymers include the polymers described in Patent Document 1. More specifically, styrene-butadiene copolymers in which the butadiene-derived structural units are brominated can be used. Among such copolymers, those in which the styrene-derived structural units are not brominated are preferred from the viewpoint of flame retardancy. Examples of such brominated styrene-butadiene polymers (brominated butadiene-styrene copolymers) in which the butadiene-derived structural units are brominated but the styrene-derived structural units are not brominated include, for example, brominated butadiene-styrene copolymers designated by CAS No. 1 195978-93-8. A brominated butadiene-styrene copolymer designated by CAS No. 1 195978-93-8 is commercially available, for example, from Chemtura Corporation under the trade name "EMERALD INNOVATION 3000."

[0016] The content of the brominated styrene-butadiene polymer in the flame retardant composition of the present invention is preferably 30 to 80 wt% based on the total weight of the composition (100 wt%), and from a cost perspective, is more preferably 40 wt% or more, and even more preferably 50 wt% or more. A low-concentration flame retardant composition of less than 30 wt% is disadvantageous in terms of cost because a large amount must be added when incorporating it into a styrene-based extruded foam. On the other hand, if the content exceeds 80 wt%, the proportion of the styrene-based resin in the flame retardant composition becomes extremely low, which tends to make the composition embrittle and difficult to manufacture. In addition, the flame retardant tends to decompose, which may lead to poor appearance of the flame retardant composition and, ultimately, poor appearance of the foam. The content of the brominated flame retardant in the present invention is preferably 0.5 to 5.0 parts by weight, more preferably 0.5 to 3.0 parts by weight, based on 100 parts by weight of the total styrene resin in the extruded styrene resin foam.

[0017] (radical generator) In the present invention, the flame retardancy of the extruded styrene resin foam can be improved by further using a radical generator. Examples of the radical generator used in the present invention include alkanes and alkenes having a phenyl group, such as 2,3-dimethyl-2,3-diphenylbutane, poly-1,4-diisopropylbenzene, 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, and also include peroxides such as dicumyl peroxide. Among these, those that are stable under resin processing temperature conditions are preferred, and specifically, 2,3-dimethyl-2,3-diphenylbutane and poly-1,4-diisopropylbenzene are preferred. The content of the radical generator in the present invention is preferably 0.05 to 5.0 parts by weight, more preferably 0.05 to 0.5 parts by weight, based on 100 parts by weight of the total styrene resin in the extruded styrene resin foam.

[0018] (anionic surfactant) In the present invention, the flame retardancy of the extruded styrene resin foam can be further improved by further using an anionic surfactant. The anionic surfactant used in the present invention is preferably alkylbenzenesulfonic acid, sodium alkylbenzenesulfonate, or sodium α-olefinsulfonate. For example, lauryl sulfate or its salts such as sodium lauryl sulfate, ammonium lauryl sulfate, or triethanolamine lauryl sulfate; or polyoxyethylene lauryl ether organic acid salts such as sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, sodium polyoxyethylene lauryl ether acetate, or ammonium laureth sulfate can be used. Among these, alkyl sulfates are preferred, and sodium lauryl sulfate is more preferred, as they have excellent dispersibility under resin processing temperature conditions. For example, this is sold by Kao Corporation under the trade name "EMAL 10PT." The content of the alkyl sulfate in the present invention is preferably 0.005 to 7.0 parts by weight, more preferably 0.01 to 5.0 parts by weight, and even more preferably 0.02 to 0.1 parts by weight, relative to 100 parts by weight of the total styrene resin in the extruded styrene resin foam.

[0019] (foaming agent) The blowing agent used in the present invention is not particularly limited, but by using a saturated hydrocarbon having 3 to 5 carbon atoms, excellent environmental compatibility can be imparted. Examples of saturated hydrocarbons having 3 to 5 carbon atoms that can be used in the present invention include propane, n-butane, i-butane, n-pentane, i-pentane, and neopentane. These may be used alone or in combination of two or more. Among these saturated hydrocarbons having 3 to 5 carbon atoms, propane, n-butane, i-butane, or a mixture of two or more of these is preferred from the viewpoint of foamability. Furthermore, from the viewpoint of the heat insulating performance of the foam, n-butane, i-butane, or a mixture of these is preferred, and i-butane is particularly preferred. From the viewpoint of improving the thermal conductivity of the foam, it is preferable to include 2.5 to 4.0 parts by weight of i-butane per 100 parts by weight of the total styrene resin in the extruded styrene resin foam. However, since i-butane is a flammable gas, adding a large amount tends to deteriorate the flame retardancy of the foam. To balance the thermal conductivity and flame retardancy, the preferred content is 2.7 to 3.7 parts by weight per 100 parts by weight of the total styrene resin in the extruded styrene resin foam.

[0020] In the present invention, furthermore, by using a blowing agent other than saturated hydrocarbons having 3 to 5 carbon atoms, a plasticizing effect and a foaming aid effect can be obtained during foam production, thereby reducing the extrusion pressure and enabling stable foam production. Other blowing agents that can be used in the present invention include, for example, ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, and tetrahydropyran; ketones such as dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-propyl ketone, and ethyl-n-butyl ketone; methanol, ethanol, propyl alcohol, and the like. Examples of suitable blowing agents include saturated alcohols having 1 to 4 carbon atoms, such as alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, and t-butyl alcohol; carboxylic acid esters, such as methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate, and ethyl propionate; alkyl halide blowing agents, such as methyl chloride and ethyl chloride; fluorinated alkyl blowing agents, such as trans-1,3,3,3-tetrafluoroprop-1-ene; inorganic blowing agents, such as water, carbon dioxide, and nitrogen; and chemical blowing agents, such as azo compounds and tetrazole. These other blowing agents may be used alone or in combination of two or more. Among these other blowing agents, saturated alcohols having 1 to 4 carbon atoms, dimethyl ether, diethyl ether, methyl ethyl ether, methyl chloride, ethyl chloride, etc. are preferred from the viewpoints of foamability, foam moldability, etc., and water, carbon dioxide, and nitrogen are preferred from the viewpoints of flammability, flame retardancy, heat insulation, etc. Furthermore, dimethyl ether is particularly preferred from the viewpoint of plasticizing effect, and water is particularly preferred from the viewpoints of cost and the effect of improving heat insulation by controlling the cell diameter.

[0021] From the above viewpoints, in the present invention, it is preferable that in addition to the saturated hydrocarbon having 3 to 5 carbon atoms, the blowing agent further contains at least one other blowing agent selected from the group consisting of water, carbon dioxide, nitrogen, alcohols having 1 to 4 carbon atoms, dimethyl ether, methyl chloride, and ethyl chloride.

[0022] The amount of the blowing agent used in the present invention (total amount of the saturated hydrocarbon and other blowing agents) is preferably 2 to 20 parts by weight, more preferably 4 to 10 parts by weight, based on 100 parts by weight of the total styrene resin in the extruded styrene resin foam. If the amount of foam used is less than 2 parts by weight, the expansion ratio will be low and the resin foam's properties such as light weight and heat insulation may not be fully exhibited, while if it exceeds 20 parts by weight, the excessive amount of blowing agent may cause defects such as voids in the foam.

[0023] (stabilizer) The stabilizer can suppress the decomposition of the flame retardant. When the extruded foam further contains a stabilizer, the extruded foam has the advantage of being excellent in flame retardancy and / or thermal stability. The stabilizer is not particularly limited, but preferred examples include epoxy compounds and polyhydric alcohol esters, which can provide extruded foams with excellent flame retardancy and thermal stability.

[0024] Examples of epoxy compounds include bisphenol A glycidyl ether, cresol novolac, and phenol novolac. Polyhydric alcohol esters are reaction products (esters) of polyhydric alcohols such as pentaerythritol, dipentaerythritol, and tripentaerythritol with monocarboxylic acids such as acetic acid and propionic acid, or dicarboxylic acids such as adipic acid and glutamic acid. The polyhydric alcohol ester may be a mixture of esters having one or more hydroxyl groups in the molecule, and may contain a small amount of the raw material polyhydric alcohol. A specific example of the polyhydric alcohol ester is a reaction mixture of dipentaerythritol and adipic acid (dipentaerythritol / adipic acid reaction mixture). The content of the epoxy compound in the present invention is preferably 0.1 to 5.0 parts by weight, more preferably 0.1 to 0.5 parts by weight, based on 100 parts by weight of the total styrene resin in the extruded styrene resin foam. The content of the polyhydric alcohol ester is preferably 0.1 to 5.0 parts by weight, more preferably 0.1 to 0.5 parts by weight, based on 100 parts by weight of the total styrene resin in the extruded styrene resin foam.

[0025] (processing aids) The processing aid is not particularly limited, but examples thereof include fatty acid metal salts, fatty acid amides, fatty acid esters, liquid paraffin, olefin waxes, etc. The fatty acid metal salt is not particularly limited, but examples thereof include sodium stearate, calcium stearate, magnesium stearate, barium stearate, etc. The content of the processing aid in the present invention is preferably 0.1 to 5.0 parts by weight, more preferably 0.1 to 0.5 parts by weight, based on 100 parts by weight of the total styrene resin in the extruded styrene resin foam.

[0026] (Bubble size adjuster) Examples of the cell diameter adjuster include talc, and the amount thereof is preferably 0.1 to 10.0 parts by weight, more preferably 0.1 to 5.0 parts by weight, per 100 parts by weight of the total styrene resin in the extruded styrene resin foam.

[0027] (Water absorption medium) In the present invention, when water is used as another blowing agent, it is preferable to add a water-absorbing substance to ensure stable extrusion foam molding. Specific examples of water-absorbing substances that can be used in the present invention include water-absorbing polymers such as hydroxyethyl cellulose, polyacrylate polymers, starch-acrylic acid graft copolymers, polyvinyl alcohol polymers, vinyl alcohol-acrylate copolymers, ethylene-vinyl alcohol copolymers, acrylonitrile-methyl methacrylate-butadiene copolymers, polyethylene oxide copolymers, and derivatives thereof, as well as fine powders having hydroxyl groups on their surfaces and particle diameters of 1000 nm or less, such as anhydrous silica (silicon oxide) having silanol groups on its surface, water-absorbing or water-swelling layered silicates such as smectite and swellable fluoromica, and their organically modified products, as well as porous substances such as zeolite, activated carbon, alumina, silica gel, porous glass, activated clay, diatomaceous earth, and bentonite. The amount of water-absorbing substance added in the present invention is adjusted as appropriate depending on the amount of water added, etc., but is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, per 100 parts by weight of the styrene-based resin.

[0028] (Manufacturing method) The method for producing the extruded styrene resin foam of the present invention includes feeding the styrene resin, the flame retardant composition, the anionic surfactant, the additives, etc. to a heating and melting means such as an extruder, adding a blowing agent to the styrene resin at any stage under high-pressure conditions to form a fluid gel, cooling the mixture to a temperature suitable for extrusion foaming, and then extruding and foaming the fluid gel through a die into a low-pressure region to form a foam. To explain in detail the process up to the step of adding the blowing agent, a mixture obtained by, for example, dry blending a styrene-based resin, a flame retardant composition, an anionic surfactant, and additives used as needed (stabilizer, radical generator, water-absorbing substance, and various other additives) is supplied to an extruder and heated, melted, and kneaded, and at a desired position in the extruder, a blowing agent is added to this kneaded mixture and the mixture is pressed into the styrene-based resin. In this way, in the present invention, a specific flame retardant composition is prepared in advance, and then this composition is used with a styrene-based resin and a blowing agent to form a foam, thereby making it possible to provide a foam that is excellent in thermal stability and flame retardancy and has an excellent appearance.

[0029] The heating temperature, melt-kneading time, and melt-kneading means used when heating and melt-kneading the styrene resin, flame retardant composition, anionic surfactant, blowing agent, and optional additives are not particularly limited. The heating temperature may be at or above the temperature at which the styrene resin melts. However, a temperature that minimizes molecular degradation of the resin, including the influence of the flame retardant brominated styrene butadiene polymer, is preferred, for example, from about 160 to 240°C, and more preferably 225°C or less. The melt-kneading time cannot be determined in general because it varies depending on the extrusion rate per unit time and the melt-kneading means, but the time required for the styrene resin and blowing agent to be uniformly dispersed and mixed is appropriately selected. Examples of melt-kneading means include screw extruders, but there are no particular limitations as long as they are used in conventional extrusion foaming. The foam molding method is not particularly limited, and a general method can be used in which, for example, a foam obtained by releasing pressure from a slit die is molded into a plate-like foam having a large cross-sectional area using a molding die and a molding roll placed in close contact with or in contact with the slit die.

[0030] The thickness of the extruded styrene resin foam of the present invention is not particularly limited and may be appropriately selected depending on the intended use. For example, in the case of a heat insulating material used in a building material or the like, a thickness as thick as a normal plate is preferred in order to impart desirable heat insulating properties, bending strength, and compressive strength, and the thickness is usually 10 to 150 mm, preferably 20 to 100 mm. The density of the extruded styrene resin foam of the present invention is set to 15 to 50 kg / m in order to provide it with light weight and excellent heat insulating properties, bending strength, and compressive strength. 3 is preferably 25 to 40 kg / m 3 It is more preferable that: The extruded styrene resin foam of the present invention is suitable for use as a heat insulating material in construction applications because of its excellent thermal stability, flame retardancy and heat insulating properties. [Example]

[0031] Hereinafter, one embodiment of the present invention will be described in detail using examples and comparative examples, although it should be understood that the present invention is not limited to the following examples.

[0032] The raw materials used in the examples and comparative examples are as follows. (A) Styrene-based resin [PS Japan Co., Ltd., 680] (B) Flame retardant Brominated styrene butadiene block polymer [Chemtura, EMERALD INNOVATION 3000, bromine content 65 wt%] (C) Radical generator Poly-1,4-diisopropylbenzene [CUROX CC-P3, manufactured by UNITED INITIATORS] (D) Surfactant Sodium lauryl sulfate [Kao, Emeral 10PT] (E) Epoxy compounds Bisphenol-A glycidyl ether [ADEKA, EP-13, epoxy equivalent 180-200g / eq.] (F) Polyhydric alcohol partial ester Dipentaerythritol-adipic acid reaction mixture [Ajinomoto Fine-Techno, Plain Riser ST210] (G) Processing aids Calcium stearate [Sakai Chemical Industry Co., Ltd., SC-P] (H) Bubble size adjuster Talc [Hayashi Kasei Co., Ltd., PHK-400] (I) Water absorption medium Bentonite [BYK Co., Ltd., Bentolite L] Silica [Evonik Degussa Japan Co., Ltd., Carplex BS-304F] (J) Foaming agent Isobutane [Mitsui Chemicals, Inc.] Dimethyl ether [Iwatani Corporation] ·Water [tap water].

[0033] The measurement and evaluation methods used in the examples and comparative examples are as follows.

[0034] (1) Foam density The foam density is calculated as the foam density (g / cm 3 ) = foam weight (g) / foam volume (cm 3 ) and the unit is (kg / m 3 ) and shown.

[0035] (2) Closed cell ratio For the extruded styrene-based resin foams obtained in each Example and Comparative Example, the direction of extrusion from the extruder was defined as the extrusion direction, the longitudinal direction of the surface perpendicular to the extrusion direction was defined as the width direction, and the transverse direction of the surface perpendicular to the extrusion direction was defined as the thickness direction. The length of the extruded foam in the extrusion direction was defined as the length of the extruded foam, the length of the extruded foam in the width direction was defined as the width of the extruded foam, and the length of the extruded foam in the thickness direction was defined as the thickness of the extruded foam. Test pieces measuring 30 mm in thickness, 25 mm in length (extrusion direction), and 25 mm in width were cut from three locations in the center of the width direction of the extruded styrene-based resin foam. The volume and other parameters of the three test pieces were measured according to Procedure C of ASTM-D2856-70, and the closed cell content of each test piece was calculated using the following formula. The average value of the three test pieces was defined as the closed cell content of the extruded styrene-based resin foam. Closed cell ratio (%)=(V1-W / ρ)×100 / (V2-W / ρ). Here, V1(cm 3 ) is the true volume of the test piece measured using an air comparison type hydrometer (Tokyo Science Co., Ltd., air comparison type hydrometer, Model 1000). The true volume is the volume excluding the volume of the non-closed cell portion. V2 (cm 3 ) is the apparent volume calculated from the dimensions of the test piece measured using a vernier caliper [Mitutoyo Corporation, M-type standard vernier caliper N30]. W (g) is the total weight of the test piece. ρ (g / cm 3) is the density of the styrene resin used in the production of the extruded styrene resin foam. The density ρ of the styrene resin used in each example and comparative example is 1.05 (g / cm 3 ) was decided.

[0036] (3) Average bubble diameter For each of the width direction cross section (TD), thickness direction cross section (HD), and extrusion direction cross section (MD) of the extruded styrene resin foams obtained in each of the Examples and Comparative Examples, images were taken at 100x magnification using a microscope (DIGITAL MICROSCOPE VHX-900, manufactured by KEYENCE CORPORATION) in accordance with ASTM D-3576. Next, a 100 mm straight line was drawn at any position on the obtained image. The number of cells on the line was counted in each image, and the average chord length (t) of the cells in the extruded styrene resin foam was calculated using the following formula: Average chord length t (μm) = 100 / (number of bubbles x image magnification) The cell diameter (D) of the cells in the extruded styrene resin foam was calculated using the following formula. Bubble diameter D (μm) = t / 0.616. The average cell diameter of the extruded styrene resin foam is the triple root of the product of the cell diameters calculated from the images of the cross sections perpendicular to each direction, and was specifically calculated using the following formula. Average bubble diameter = (bubble diameter in HD image × bubble diameter in TD image × bubble diameter in MD image) 1 / 3

[0037] (4) Thermal conductivity (W / mK) The thermal conductivity of the extruded styrene resin foams obtained in each of the Examples and Comparative Examples, 7 days after production, was measured in accordance with JIS A9511. For the thermal conductivity measurement, a single test piece having a thickness of 25 mm, a width of 100 mm, and a length of 300 mm, obtained by arranging three extruded styrene resin foams having a thickness of 25 mm, a width of 100 mm, and a length of 300 mm in the width direction, was used as a measurement sample.

[0038] (5) JIS flammability The measurement was conducted in accordance with JIS A9511:2006R (measurement method A was adopted), using test pieces with a thickness of 10 mm, length of 200 mm, and width of 25 mm. After producing an extruded styrene resin foam, the foam was cut into test pieces of the above dimensions and left to stand under standard temperature condition class 3 (23°C ± 5°C) and standard humidity condition class 3 (50 + 20, -10% RH) conditions specified in JIS K7100, and 7 days after the foam was produced, the measurement was conducted. As the evaluation standard for JIS flammability, the flame-out time was calculated as the average value of the measurement results for five test pieces.

[0039] Example 1 [Preparation of resin mixture] A resin mixture consisting of 100 parts by weight of (A) styrene-based resin (680) was dry-blended with 2.3 parts by weight of EMERALD INNOVATION 3000 as a flame retardant, 0.2 parts by weight of CUROX CC-P3 as a radical generator, 0.03 parts by weight of EMALE 10PT as an anionic surfactant, 0.2 parts by weight of EP-13 as an epoxy compound, 0.2 parts by weight of PLENLYZER ST210 as a polyhydric alcohol partial ester, 0.2 parts by weight of SC-P as a processing aid, 0.8 parts by weight of talc as a cell size adjuster, and 0.5 parts by weight of VENTOLITE L and 0.3 parts by weight of CARPLEX BS-304F as water-absorbing media. This dry blend is abbreviated as [GP].

[0040] [Preparation of extruded foam] The resulting GP was fed at approximately 800 kg / hr to a 150 mm diameter single-screw extruder, a 200 mm diameter single-screw extruder, and a cooler connected in series. The resin mixture fed to the first extruder was heated to a resin temperature of 230°C to melt, plasticize, and knead. 3.7 parts by weight of isobutane and 2.0 parts by weight of dimethyl ether (J) as blowing agents, and 0.9 parts by weight of water (tap water) per 100 parts by weight of styrene-based resin, were injected into the resin near the tip of the first extruder. The resin was then cooled to 120°C in a second extruder and cooler connected to the first extruder, and extruded into the atmosphere through a die with a rectangular cross-section measuring 2 mm thick and 400 mm wide, located at the tip of the cooler, and foamed. An extruded foam with a cross-sectional shape measuring 60 mm thick and 1000 mm wide was then obtained using a molding die placed in close contact with the die and a molding roll placed downstream of it. This was then cut with a cutter to a thickness of 50 mm, width 910 mm and length 1820 mm, yielding a foam.

[0041] (Examples 2 to 6, Comparative Examples 1 and 2) Foams were obtained in the same manner as in Example 1, except that the amounts of flame retardant and stabilizer and the anionic surfactant were changed as shown in Table 1. The properties of the obtained foams are shown in Table 1.

[0042] Compared with the extruded foams of Comparative Examples 1 and 2, which did not use an anionic surfactant, the extruded foams of Examples 1 to 6 had a low average JIS flammability time of less than 1 second, and the standard deviation evaluating the variation among five test pieces was also small, less than 0.3, indicating that they had excellent flammability.

[0043] [Table 1]

Claims

1. 1. An extruded styrene-based resin foam comprising a styrene-based resin, a brominated flame retardant, and an anionic surfactant, wherein the brominated flame retardant is a brominated styrene-butadiene polymer.

2. 2. The extruded styrene-based resin foam according to claim 1, wherein the brominated styrene-butadiene polymer is contained in an amount of 0.5 to 3.0 parts by weight per 100 parts by weight of the total amount of the styrene-based resin.

3. 3. The extruded styrene resin foam according to claim 1, wherein the anionic surfactant is contained in an amount of 0.01 to 0.1 parts by weight per 100 parts by weight of the total amount of the styrene resin.

4. The extruded styrene resin foam according to any one of claims 1 to 3, wherein the anionic surfactant is an alkyl sulfate.

5. The extruded styrene-based resin foam according to any one of claims 1 to 4, further comprising a radical generator, wherein the radical generator is contained in an amount of 0.05 to 0.5 parts by weight per 100 parts by weight of the total amount of the styrene-based resin.

6. 6. The extruded styrene resin foam according to claim 5, wherein the radical generator is 2,3-dimethyl-2,3-diphenylbutane and / or poly-1,4-diisopropylbenzene.

7. The extruded styrene resin foam according to any one of claims 1 to 6, which passes the combustion test method of JIS A9511.

8. The extruded styrene resin foam according to any one of claims 1 to 7, characterized in that the extruded styrene resin foam has a combustion time of less than 1.0 second on average and a standard deviation of less than 0.3 in a combustion test according to JIS A9511.

9. The extruded styrene resin foam board according to any one of claims 1 to 8, wherein the extruded styrene resin foam is an extruded styrene resin foam board.

10. A method for producing an extruded foam by extruding and foaming a styrene-based resin composition containing a styrene-based resin, a brominated flame retardant, and an anionic surfactant, wherein the brominated flame retardant is a brominated styrene-butadiene polymer.

11. The method for producing an extruded styrenic resin foam according to claim 10, comprising a step of mixing the styrenic resin with an anionic surfactant.

12. 12. The method for producing an extruded styrene resin foam according to claim 10, wherein the blowing agent is at least one selected from saturated hydrocarbons having 3 to 5 carbon atoms.

13. The method for producing an extruded styrene resin foam according to claim 12, further comprising, as a blowing agent, at least one selected from the group consisting of water, carbon dioxide, nitrogen, alcohols having 1 to 4 carbon atoms, dimethyl ether, methyl chloride, and ethyl chloride.

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