Manufacturing method for extruded polystyrene resin foam board

Abstract

To provide a method for manufacturing a polystyrene-based resin foam plate which can maintain low thermal conductivity over a long period of time, is excellent in manufacturing stability and has good appearance.SOLUTION: There is provided a method for manufacturing a polystyrene-based resin foam plate, wherein a polystyrene-based resin contains two kinds of polystyrene-based resins A and B having different melt tensions and melt flow rates in a blending weight ratio (A:B) of 25:75 to 90:10, the total addition amount of the physical foaming agent is 1 mol or more and 1.8 mol or less with respect to 1 kg of a base material resin, the physical foaming agent contains 1,1,1,4,4,4-hexafluoro-2-butene and dialkyl ether having 1 to 3 carbon atoms, addition amounts of fluorine-containing alkene and ether are 0.3 mol or more and 1.1 mol or less, and 0.05 mol or more and 0.8 mol or less with respect to 1 kg of the base material resin, and a ratio of the addition amount (mol / kg) of the fluorine-containing alkene to the addition amount (mol / kg) of the ether is 1 to 10.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing an extruded polystyrene resin foam board, and more particularly to a method for producing an extruded polystyrene resin foam board that can be suitably used as a heat insulating material for walls, floors, roofs, etc. of buildings. [Background technology]

[0002] Extruded polystyrene resin foam boards (hereinafter simply referred to as "foam boards") are widely used as building insulation materials due to their excellent thermal insulation properties and mechanical strength. Such foam boards are generally produced by heating and melting polystyrene resin in an extruder, then injecting and kneading a physical blowing agent into the resulting melt to obtain a foamable molten resin mixture, which is then extruded into a low-pressure region through a flat die or the like attached to the tip of the extruder to foam, and then molding the mixture into a board using a molding tool.

[0003] In recent years, there has been an increasing demand for energy conservation in homes, buildings, and the like, creating a growing demand for extruded polystyrene resin foam boards with excellent thermal insulation properties. One method for producing extruded polystyrene resin foam boards with excellent thermal insulation properties is to use a blowing agent made of a hydrofluoroolefin (hereinafter simply referred to as "HFO") such as 1,3,3,3-tetrafluoropropene or 1-chloro-3,3,3-trifluoropropene (see, for example, Patent Documents 1 and 2). These HFOs are non-flammable and have low thermal conductivity, making it possible to impart high thermal insulation properties. Furthermore, they are environmentally friendly blowing agents because they have very low ozone depletion potential and global warming potential.

[0004] In Patent Documents 1 and 2, 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz) is used as the HFO, either alone or in combination with other blowing agents. The HFO-1336mzz used in Patent Documents 1 and 2 is excellent in maintaining the thermal conductivity of the foam board low over a long period of time (long-term low thermal conductivity). Therefore, there is a need for the production of foam boards that can maintain low thermal conductivity by using HFO-1336mzz as a blowing agent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2010-522808 [Patent Document 2] Special Publication No. 2019-515112 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when manufacturing foam boards, if an excessive amount of HFO-1336mzz is added in an attempt to maintain a lower thermal conductivity, problems arise in that the foaming agent separates from the resin, deteriorating moldability, and when HFO-1336mzz is used in combination with other foaming agents, moldability can also deteriorate depending on the blending ratio.As described above, when HFO-1336mzz is used, manufacturing stability is poor, and there is a possibility that a foam board with a good appearance cannot be obtained.

[0007] The present invention has been made in view of the above background, and aims to provide a method for producing a polystyrene-based resin foam board that can maintain low thermal conductivity for a long period of time, has excellent production stability, and has a good appearance. [Means for solving the problem]

[0008] According to the present invention, there is provided the following method for producing an extruded polystyrene resin foam board.

[0009] [1] A foaming method for producing a foamable molten resin composition having an apparent density of 20 kg / m, which comprises a step of extruding and foaming a foamable molten resin composition obtained by kneading a base resin mainly composed of a polystyrene resin, a flame retardant, and a physical foaming agent, and molding the extrudate into a plate. 3 More than 50kg / m 3 The following method for producing an extruded polystyrene resin foam board: The polystyrene resin contains polystyrene resin A having a melt tension of 10 cN or more at 200°C and a melt flow rate of 7 g / 10 min or less as measured at 200°C under a load of 5 kg, and polystyrene resin B having a melt tension of less than 10 cN at 200°C and a melt flow rate of more than 7 g / 10 min as measured at 200°C under a load of 5 kg, the weight ratio of the blending amount of the polystyrene-based resin A to the blending amount of the polystyrene-based resin B (polystyrene-based resin A:polystyrene-based resin B) is 25:75 to 90:10; the total amount of the physical foaming agent added is 1 mol or more and 1.8 mol or less per 1 kg of the base resin, the physical blowing agent contains 1,1,1,4,4,4-hexafluoro-2-butene and a dialkyl ether having 1 to 3 carbon atoms; the amount of 1,1,1,4,4,4-hexafluoro-2-butene added is 0.3 mol or more and 1.1 mol or less per 1 kg of the base resin; the amount of the dialkyl ether having 1 to 3 carbon atoms added is 0.05 mol or more and 0.8 mol or less per 1 kg of the base resin, A method for producing an extruded polystyrene resin foam board, wherein the ratio of the amount (mol / kg) of the 1,1,1,4,4,4-hexafluoro-2-butene added to the amount (mol / kg) of the dialkyl ether having 1 to 3 carbon atoms added is 1 to 10.

[0010] [2] The method for producing an extruded polystyrene resin foam board according to the invention [1], wherein the amount of 1,1,1,4,4,4-hexafluoro-2-butene added is 0.6 mol or more and 0.9 mol or less per kg of the base resin.

[0011] [3] The method for producing an extruded polystyrene resin foam board according to the invention [1] or [2], characterized in that the amount of the dialkyl ether having 1 to 3 carbon atoms added is 0.1 mol or more and 0.6 mol or less per kg of the base resin.

[0012] [4] The method for producing an extruded polystyrene resin foam board according to any one of the inventions [1] to [3], characterized in that the ratio of the amount (mol / kg) of the 1,1,1,4,4,4-hexafluoro-2-butene to the amount (mol / kg) of the dialkyl ether having 1 to 3 carbon atoms is 2 to 3.5.

[0013] [5] The method for producing an extruded polystyrene foam board according to any one of the inventions [1] to [4], wherein the polystyrene resin B contains a polystyrene resin b, and the polystyrene resin b is a recycled raw material derived from scraps and / or crushed extruded polystyrene foam boards.

[0014] [6] The method for producing an extruded polystyrene foam board according to any one of the above [1] to [5] inventions, characterized in that the thickness of the extruded polystyrene foam board is 20 mm or more. [Effects of the Invention]

[0015] According to the manufacturing method of the present invention, it is possible to provide a method for manufacturing a polystyrene resin foam board that can maintain low thermal conductivity for a long period of time, has excellent manufacturing stability, and has a good appearance. DETAILED DESCRIPTION OF THE INVENTION

[0016] The method for producing an extruded polystyrene resin foam board of the present invention will be described in detail below. The method for producing an extruded polystyrene resin foam board of the present invention includes a step of extruding and foaming an expandable resin composition obtained by kneading a base resin mainly composed of a polystyrene resin (hereinafter also referred to as "polystyrene resin K"), a flame retardant, and a physical blowing agent, and forming the composition into a board. 3 More than 50kg / m 3 The following is a method for producing an extruded polystyrene resin foam board.

[0017] Specifically, a base resin consisting of polystyrene resin K and other resins added as needed, a flame retardant, other additives added as needed, and a physical foaming agent are pressed into the extruder, melted and kneaded under heating to form a foamable resin melt, which is then adjusted to an appropriate foaming temperature and extruded from the high-pressure extruder into a low-pressure region through a flat die to foam it, and a forming tool such as a forming mold (for example, a shaping device (hereinafter also referred to as a guider) consisting of two upper and lower plates of polytetrafluoroethylene resin or the like arranged parallel to each other or so as to gradually expand from the entrance toward the exit) or a forming roll is placed at the outlet of the flat die, and the extruded foam composition is molded into a plate by passing through the forming tool.

[0018] In the present invention, by blending a specific polystyrene-based resin K (polystyrene-based resin A, polystyrene-based resin B) described below in a specific blending amount and further adding a specific foaming agent (foaming agent A, foaming agent B) described below in a specific addition amount, it is possible to obtain a foamed board that can maintain low thermal conductivity for a long period of time, has excellent manufacturing stability, and has a good appearance.

[0019] <Base resin> (Polystyrene Resin K) Examples of the polystyrene resin K used in the production method of the present invention include polystyrene (general-purpose polystyrene: GPPS), and one or more selected from the group consisting of styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers, styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-maleic anhydride copolymers, styrene-polyphenylene ether copolymers, styrene-acrylonitrile copolymers, styrene-methylstyrene copolymers, styrene-dimethylstyrene copolymers, styrene-ethylstyrene copolymers, and styrene-diethylstyrene copolymers, each containing 50 mol% or more of styrene unit components. Among these, polystyrene is preferred. The polystyrene resin may also contain unit components derived from a branching agent such as a polyfunctional monomer or a polyfunctional macromonomer. The content of styrene unit components in the copolymer is preferably 60 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0020] In the present invention, a base resin having polystyrene-based resin K as a main component means that 50% by weight or more of the base resin is a polystyrene-based resin, preferably 70% by weight or more, more preferably 80% by weight or more, and even more preferably 90% by weight or more.

[0021] The melt viscosity of the polystyrene resin K used in the production method of the present invention is preferably 500 to 3000 Pa·s, more preferably 1000 to 2500 Pa·s, and even more preferably 1500 to 2300 Pa·s, in order to provide excellent foaming and moldability. In this specification, the melt viscosity is measured based on JIS K7199:1999 at a temperature of 200°C and a shear rate of 100 sec -1 The values ​​were measured under the following conditions.

[0022] Specifically, the polystyrene resin K in the present invention includes a polystyrene resin A and a polystyrene resin B.

[0023] (Polystyrene Resin A) Polystyrene resin A has a melt tension of 10 cN or more at 200°C and a melt flow rate (hereinafter also referred to as "MFR") of 7 g / 10 min or less measured under a load of 5 kg at 200°C. By using polystyrene resin A that satisfies these conditions, an extruded foam board with excellent manufacturing stability and appearance can be obtained.

[0024] From the viewpoints of further improving production stability and improving appearance, the melt tension of the polystyrene resin A at 200°C is preferably 12 cN or more, more preferably 15 cN or more, and even more preferably 20 cN or more. The upper limit of the melt tension of the polystyrene resin A at 200°C is, for example, 100 cN, and preferably 50 cN.

[0025] The MFR of polystyrene resin A measured at 200°C under a load of 5 kg is preferably 6 g / 10 min or less, more preferably 5 g / 10 min or less, from the viewpoint of further improving production stability and obtaining an extruded foam board with excellent appearance. The lower limit of the MFR of polystyrene resin A is, for example, 0.5 g / 10 min.

[0026] Any polystyrene-based resin satisfying the above-mentioned melt tension and MFR conditions is used as the polystyrene-based resin A. Note that the polystyrene-based resin A may contain two or more polystyrene-based resins satisfying the above-mentioned conditions. When the polystyrene-based resin A is made up of two or more polystyrene-based resins, the melt tension of each polystyrene-based resin is determined, and the melt tension calculated taking into account the blending ratio of each polystyrene-based resin in the polystyrene-based resin A should be 10 cN or more. Similarly, the MFR of each polystyrene-based resin is determined, and the MFR calculated taking into account the blending ratio of each polystyrene-based resin in the polystyrene-based resin A should be 7 g / 10 min or less.

[0027] (Polystyrene resin B) Polystyrene resin B has a melt tension at 200°C of less than 10 cN and a melt flow rate measured at 200°C under a load of 5 kg of more than 7 g / 10 min.

[0028] From the viewpoint of obtaining a foamed board having a good appearance and a low apparent density after extrusion foaming, the melt tension of polystyrene resin B at 200°C is preferably 8 cN or less, more preferably 6 cN or less. The lower limit of the melt tension of polystyrene resin B at 200°C is, for example, 1 cN.

[0029] The MFR of polystyrene resin B measured at 200°C under a load of 5 kg is preferably 10 g / 10 min or more, more preferably 15 g / 10 min or more, from the viewpoint of easily maintaining high fluidity of the foamable resin melt even under conditions of a relatively low extrusion temperature. The upper limit of the MFR of polystyrene resin B is, for example, 35 g / 10 min, and preferably 25 g / 10 min.

[0030] Any polystyrene-based resin satisfying the above-mentioned melt tension and MFR conditions is used as polystyrene-based resin B. Note that polystyrene-based resin B may contain two or more polystyrene-based resins satisfying the above-mentioned conditions. When polystyrene-based resin B is made up of two or more polystyrene-based resins, the melt tension of each polystyrene-based resin is determined, and the melt tension calculated taking into account the blending ratio of each polystyrene-based resin in polystyrene-based resin B should be less than 10 cN. Similarly, the MFR of each polystyrene-based resin is determined, and the MFR calculated taking into account the blending ratio of each polystyrene-based resin in polystyrene-based resin B should be more than 7 g / 10 min.

[0031] As the polystyrene-based resin B, for example, commercially available general-purpose polystyrene, recycled raw materials of polystyrene-based resin foam bead moldings used in fish boxes, etc., or recycled raw materials of polystyrene-based resin extruded foam boards can be used.

[0032] The polystyrene resin B of the present invention preferably contains a polystyrene resin b, which is a recycled raw material derived from scraps of extruded polystyrene foam boards and / or crushed materials. The polystyrene resin b is a recycled polystyrene resin obtained by, for example, heating and melting scraps of extruded polystyrene foam boards and / or crushed materials of extruded polystyrene foam boards and pelletizing them. Examples of the scraps of foam boards and / or crushed materials include scraps of foam boards obtained by cutting extruded polystyrene foam boards and crushed materials obtained by crushing extruded polystyrene foam boards.

[0033] From the viewpoint of recycling, the blending amount of polystyrene resin b in polystyrene resin B is preferably 70% by weight or more, more preferably 80% by weight or more, and even more preferably 90% by weight or more.

[0034] (Polystyrene Resin C) In addition to the polystyrene resin A and the polystyrene resin B, the polystyrene resin K may also contain the polystyrene resin C within a range that does not impair the objects and effects of the present invention.

[0035] Examples of polystyrene resin C include polystyrene resins having a melt tension of 10 cN or more at 200°C and an MFR of more than 7 g / 10 min measured at 200°C under a load of 5 kg, and / or polystyrene resins having a melt tension of less than 10 cN at 200°C and an MFR of 7 g / 10 min or less measured at 200°C under a load of 5 kg.

[0036] The specific method for determining the melt tension at 200°C of polystyrene resin A and polystyrene resin B is as follows: The melt tension of polystyrene resin A and polystyrene resin B is measured in accordance with ASTM D1238 using, for example, a Capilograph 1D (manufactured by Toyo Seiki Seisakusho, Ltd.). Using a cylinder with a diameter of 9.55 mm and a length of 350 mm and an orifice with a nozzle diameter of 2.095 mm and a length of 8.0 mm, the set temperatures of the cylinder and orifice were set to 200°C (MT200), the required amount of sample was placed in the cylinder, and after leaving it for 4 minutes, the piston speed was set to 10 mm / min and the molten resin was extruded from the orifice in the form of a string, and this string-like material was hung on a tension detection pulley with a diameter of 45 mm. The string-like material was taken up by the take-up roller while the take-up speed was increased at a constant rate so that it reached 200 m / min from 0 m / min in 4 minutes, and the maximum tension value just before the string-like material broke was obtained.

[0037] The reason for setting the time required for the take-up speed to reach 200 m / min from 0 m / min to 4 minutes is to suppress thermal degradation of the resin and to improve the reproducibility of the obtained values. The above procedure was repeated 10 times using different samples, and the three largest and three smallest maximum values ​​obtained from the 10 measurements were discarded. The arithmetic mean of the remaining four intermediate maximum values ​​was taken as the melt tension (cN).

[0038] However, if the melt tension is measured using the above method and the string-like material does not break even when the take-up speed reaches 200 m / min, the melt tension (cN) obtained by keeping the take-up speed at a constant speed of 200 m / min is used. Specifically, similar to the above measurement, molten resin is extruded into a string-like shape from an orifice, and this string-like material is hung on a tension detection pulley. The take-up roller is rotated while the take-up speed is increased at a constant rate so that it reaches 200 m / min over 4 minutes, and the rotation speed is waited until it reaches 200 m / min. Melt tension data acquisition begins after the rotation speed reaches 200 m / min, and data acquisition is completed after 30 seconds. The average value (Tave) of the maximum tension (Tmax) and the minimum tension (Tmin) obtained from a tension load curve obtained during this 30-second period, with melt tension on the vertical axis and time on the horizontal axis, is defined as the melt tension in this specification.

[0039] The MFR of polystyrene resin A and polystyrene resin B is a value measured based on JIS K7210-1:2014 under conditions of a test temperature of 200°C and a nominal load of 5 kg.

[0040] (Other polymers) The base resin may contain polymers other than the polystyrene-based resin K as long as the objectives and effects of the present invention are achieved. Examples of other polymers include amorphous polyethylene terephthalate-based resins (heat of fusion less than 5 J / g, as measured by heat flux differential scanning calorimetry in accordance with JIS K7122-1987), polyethylene-based resins (a mixture of one or more selected from the group consisting of ethylene homopolymers and ethylene-based copolymers having an ethylene unit component content of 50 mol% or more), polypropylene-based resins (a mixture of one or more selected from the group consisting of propylene homopolymers and propylene-based copolymers having a propylene unit component content of 50 mol% or more), polyphenylene ether-based resins, and polymethyl methacrylate, as well as thermoplastic elastomers such as styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, hydrogenated styrene-butadiene-styrene block copolymers, hydrogenated styrene-isoprene-styrene block copolymers, and styrene-ethylene copolymers. These other polymers may be appropriately blended within a range that does not impair the objectives and effects of the present invention.

[0041] The weight ratio of the blended amount of polystyrene resin A to the blended amount of polystyrene resin B (polystyrene resin A:polystyrene resin B) is 25:75 to 90:10. By setting the blended amounts of polystyrene resin A and polystyrene resin B within the above ranges, it is possible to improve the closed cell ratio and obtain a foam board with a good appearance and low apparent density. From the viewpoint of further improving the above effects, it is preferable that the weight ratio of the blended amount of polystyrene resin A to the blended amount of polystyrene resin B (polystyrene resin A:polystyrene resin B) is 40:60 to 80:20.

[0042] When the entire polystyrene-based resin K is taken as 100% by weight, the sum of the amount of polystyrene-based resin A and the amount of polystyrene-based resin B is preferably 70% by weight or more, more preferably 80% by weight or more, and even more preferably 90% by weight or more. It is particularly preferable that the polystyrene-based resin K consists essentially of polystyrene-based resin A and polystyrene-based resin B.

[0043] <Physical foaming agent> The physical blowing agent used in the present invention contains, as essential components, blowing agent A consisting of 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz) and blowing agent B consisting of a dialkyl ether having 1 to 3 carbon atoms.

[0044] (Blowing agent A) Among hydrofluoroolefins, blowing agent A, 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz), has moderate solubility in polystyrene resins and excellent retention within the foam, allowing for the production of foam boards with excellent low thermal conductivity over a long period of time. It is also nonflammable, reducing the risk of ignition due to static electricity during foam board production. Furthermore, it has a low ozone depletion potential and a very low global warming potential, making it an environmentally friendly blowing agent. However, adding excessive amounts of blowing agent A can sometimes deteriorate the appearance of the extruded foam board.

[0045] (Blowing agent B) Examples of the C1-3 dialkyl ether of the blowing agent B include dimethyl ether, diethyl ether, dipropyl ether, and methyl ethyl ether, which can be used alone or in combination of two or more. From the viewpoint of improving production stability, dimethyl ether is preferably used among these. The C1-3 dialkyl ether means a dialkyl ether having an alkyl chain with 1 to 3 carbon atoms.

[0046] Dialkyl ethers having 1 to 3 carbon atoms (especially dimethyl ethers) do not deplete the ozone layer or contribute to global warming, and since they quickly dissipate from the foam board, they can quickly stabilize the shape of the foam board. Furthermore, the use of dialkyl ethers having 1 to 3 carbon atoms allows foam boards with lower apparent density (higher expansion ratio) to be obtained.

[0047] (Foaming agent C) In the present invention, blowing agent A and blowing agent B are used as essential physical blowing agents, but other blowing agent C can be appropriately added to the physical blowing agent as long as the effects of the present invention are not impaired. Examples of blowing agent C include early-dissipation blowing agents such as water, carbon dioxide, and aliphatic alcohols having 1 to 5 carbon atoms, which can be used alone or in combination of two or more. Among these, water and / or aliphatic alcohols having 1 to 5 carbon atoms are preferred as blowing agent C.

[0048] Examples of aliphatic alcohols having 1 to 5 carbon atoms include monohydric alcohols such as methyl alcohol (methanol), ethyl alcohol (ethanol), n-propyl alcohol, isopropyl alcohol, butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, aryl alcohol, crotyl alcohol, propargyl alcohol, n-amyl alcohol, sec-amyl alcohol, isoamyl alcohol, tert-amyl alcohol, neopentyl alcohol, 3-pentanol, 2-methyl-1-butanol, and 3-methyl-2-butanol. These can be used alone or in combination of two or more. Among these, ethanol is preferred for improving the appearance. The ratio of ethanol to 100% by weight of aliphatic alcohols having 1 to 5 carbon atoms is preferably 60% by weight or more, more preferably 70% by weight or more, and even more preferably 85% by weight or more.

[0049] <Amount of physical foaming agent added> In the present invention, the total amount of physical foaming agent added is 1 mol or more and 1.8 mol or less per 1 kg of base resin. By setting the total amount of physical foaming agent added within this range, a foam board with excellent appearance, low apparent density, and the ability to maintain low thermal conductivity for a long period of time can be obtained. From the viewpoint of further improving the above effects, the total amount of physical foaming agent added is preferably 1.2 mol or more and 1.6 mol or less, and more preferably 1.3 mol or more and 1.5 mol or less per 1 kg of base resin.

[0050] The amount of blowing agent A (1,1,1,4,4,4-hexafluoro-2-butene) added is 0.3 mol or more per kg of base resin. By setting the amount of blowing agent A added within this range, it is possible to maintain low thermal conductivity for a long period of time. From the viewpoint of maintaining low thermal conductivity for a further long period of time, the amount of blowing agent A added is preferably 0.4 mol or more, more preferably 0.6 mol or more, per kg of base resin.

[0051] On the other hand, from the viewpoint of improving production stability, the amount of foaming agent A added is 1.1 mol or less, preferably 0.90 mol or less, and more preferably 0.80 mol or less, per kg of base resin.

[0052] In the present invention, in a high-mixing extruder such as a twin screw or screw with a large ratio of axial length to screw diameter, or a tandem extruder in which a first extruder and a second extruder are connected in series, a continuous static mixer may be used at the connection between the first extruder and the second extruder or at the connection between the second extruder and the die, as needed, to facilitate the production of extruded foam plates with excellent appearance even when a large amount of blowing agent A is added.

[0053] The amount of foaming agent B (dialkyl ether having 1 to 3 carbon atoms) added is 0.05 mol or more and 0.8 mol or less per 1 kg of base resin. By setting the amount of foaming agent B added within this range, it is possible to obtain a foamed board with excellent production stability and a desired apparent density. Furthermore, from the viewpoint of improving the appearance, the amount of foaming agent B added is preferably 0.1 mol or more and 0.6 mol or less, and more preferably 0.2 mol or more and 0.5 mol or less.

[0054] From the viewpoint of improving production stability, the ratio of the amount (mol / kg) of blowing agent A (1,1,1,4,4,4-hexafluoro-2-butene) added to the amount (mol / kg) of blowing agent B (dialkyl ether having 1 to 3 carbon atoms) added (blowing agent A / blowing agent B) is 1 to 10. Furthermore, from the viewpoint of improving the appearance, it is preferably 1.5 to 6, and more preferably 2 to 3.5.

[0055] When foaming agent C is added, the amount is, for example, 0.1 mol to 0.7 mol, and preferably 0.3 mol to 0.6 mol, per 1 kg of base resin. When water and an aliphatic alcohol having 1 to 5 carbon atoms are used as foaming agent C, the amount is preferably, for example, 0.09 mol to 0.4 mol of water per 1 kg of base resin and 0.01 mol to 0.3 mol of an aliphatic alcohol having 1 to 5 carbon atoms per 1 kg of base resin.

[0056] In the present invention, by setting the blending amounts of polystyrene resins A and B, the total amount of physical foaming agent added, the amount of foaming agents A and B added, and the ratio of the amount of foaming agent A added to the amount of foaming agent B added within the above-mentioned specific ranges, it is possible to maintain low thermal conductivity for a long period of time, and to easily obtain a foamed board with excellent production stability and good appearance.

[0057] <Other ingredients> (Flame retardant) The foam board obtained by the manufacturing method of the present invention is mainly used as a heat insulating material for building materials, and flame retardancy is imparted by blending a flame retardant with the base resin. The flame retardant used in the present invention is not particularly limited, but it is preferable to use a brominated flame retardant. Examples of the brominated flame retardant include brominated butadiene polymers such as brominated butadiene-styrene copolymers, tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-S-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-A-bis(2,3-dibromopropyl ether), tetrabromobisphenol-B-bis(2,3-dibromopropyl ether), tetrabromobisphenol-C-bis(2,3-dibromopropyl ether), tetrabromobisphenol-D ... Examples include brominated bisphenol compounds such as tetrabromobisphenol-S-bis(2,3-dibromopropyl ether) and tetrabromobisphenol-F-bis(2,3-dibromopropyl ether), and brominated isocyanurates such as tris(2,3-dibromopropyl)isocyanurate, mono(2,3,4-tribromobutyl)isocyanurate, di(2,3,4-tribromobutyl)isocyanurate, and tris(2,3,4-tribromobutyl)isocyanurate. These brominated flame retardants can be used alone or in combination.

[0058] In addition to these bromine-based flame retardants, nitrogen-containing cyclic compounds such as cresyl di-2,6-xylenyl phosphate, antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, pentabromotoluene, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, melamine, melam, and melem; inorganic compounds such as silicone compounds, boron oxide, zinc borate, and zinc sulfide; and phosphorus compounds such as phosphate esters represented by triphenyl phosphate, red phosphorus, ammonium polyphosphate, phosphazene, and hypophosphites.

[0059] Among these flame retardants, it is more preferable to use a flame retardant containing a combination of tetrabromobisphenol A-bis(2,3-dibromopropyl ether) and tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), or a flame retardant containing a brominated butadiene-styrene copolymer, because these can impart high flame retardancy, are less likely to decompose the polystyrene resin during extrusion, and make it easier to stably obtain foamed boards even when the foamed board has a low apparent density (high expansion ratio) and a large cross-sectional area.

[0060] The amount of flame retardant added is preferably 0.1 to 10 parts by weight, more preferably 1 to 9 parts by weight, and even more preferably 1.5 to 7 parts by weight, per 100 parts by weight of the base resin, because this allows the foam board to have high flame retardancy while suppressing deterioration in extrusion foamability and mechanical properties. Within this range, the flame retardant does not inhibit foamability, and a foam board can be obtained that exhibits high flame retardancy, as specified in "Test Method A" for extruded polystyrene foam insulation, which is defined in JIS A9521:2022, Test Methods for Flammability of Foamed Plastic Insulation Materials.

[0061] (Flame retardant synergist) In the method of the present invention, a flame retardant synergist can be used in combination with the flame retardant to further improve the flame retardancy of the foam board. Examples of the flame retardant synergist include one or more selected from diphenylalkanes and diphenylalkenes such as 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, and polyalkylated aromatic compounds such as poly-1,4-diisopropylbenzene. The amount of the flame retardant synergist added is generally 0.01 to 1 part by weight, more preferably 0.05 to 0.5 parts by weight, per 100 parts by weight of the base resin.

[0062] (Radiation suppressant) In the production method of the present invention, graphite can be added to the foamable molten resin composition as a radiation suppressor to improve the heat insulating properties of the foam board by reflecting infrared rays.

[0063] Examples of graphite include flake graphite, scaly graphite, artificial graphite, and amorphous graphite, and it is preferable to use graphite whose main component is flake graphite. As described below, graphite is preferably used as a masterbatch in which it is added to a polystyrene resin at a high concentration. Graphite with a fixed carbon content of 80% or more is preferred because it provides good workability when producing the masterbatch and is effective in improving the thermal insulation of the resulting foam board. Furthermore, to further improve the thermal insulation of the foam board, graphite with a fixed carbon content of 90% or more is more preferred, and graphite with a fixed carbon content of 95% or more is even more preferred. The fixed carbon content of the graphite refers to a value measured by the method described in JIS M8511:2014.

[0064] When graphite is added, the amount of graphite added is preferably 0.2 to 10 parts by weight per 100 parts by weight of the base resin. When the amount added is within this range, the heat insulating properties are improved, and a foam board with the desired low thermal conductivity can be obtained. From this perspective, the amount of graphite added is more preferably 0.3 parts by weight or more, and even more preferably 0.4 parts by weight or more, per 100 parts by weight of the base resin. On the other hand, from the perspective of maintaining the flame retardancy of the foam board, the upper limit of the amount of graphite added is more preferably 5 parts by weight, even more preferably 3 parts by weight, and particularly preferably 1 part by weight, per 100 parts by weight of the base resin.

[0065] In the manufacturing method of the present invention, a radiation suppressor other than the graphite can be incorporated into the foam board to further improve heat insulation. Examples of radiation suppressors other than graphite include one or more selected from metal oxides such as titanium oxide, metals such as aluminum, ceramics, carbon black, graphite, infrared-shielding pigments, and hydrotalcite. Among these, titanium oxide is preferably used. The amount of the radiation suppressor other than graphite added is generally 0.5 to 5 parts by weight, more preferably 1 to 4 parts by weight, per 100 parts by weight of the base resin.

[0066] In the method of the present invention, other known additives may be added to the base resin as needed, such as cell regulators, colorants (e.g., pigments and dyes), heat stabilizers, and fillers.

[0067] (Foam adjuster) In the manufacturing method of the present invention, a foamable resin composition is preferably formed by adding a cell regulator to the base resin. Examples of the cell regulator include inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, clay, aluminum oxide, bentonite, and diatomaceous earth. Among these, talc is preferred because it is easy to control the cell size and can easily reduce the cell size without impairing flame retardancy. Fine talc with a 50% particle size (measured by centrifugal sedimentation using light transmission) of 0.1 to 20 μm is particularly preferred, with talc of 0.5 to 15 μm being particularly preferred. The amount of cell regulator added varies depending on the type of regulator, the desired cell size, and other factors. When talc is used as a cell regulator, the amount is preferably 0.1 to 7 parts by weight, more preferably 0.2 to 5 parts by weight, and even more preferably 0.3 to 3 parts by weight per 100 parts by weight of the base resin.

[0068] (heat stabilizer) The thermal stabilizer can be incorporated into raw materials or waste materials during foam board production or when recycling and repelletizing foam board waste materials, thereby improving the thermal stability of the brominated flame retardant. Examples of the thermal stabilizer include one or more selected from bisphenol-type epoxy compounds and novolac-type epoxy compounds, such as those in the EPICLON series manufactured by DIC Corporation; hindered phenol compounds, such as pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; and phosphite compounds, such as bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite. The amount of the thermal stabilizer added is preferably 0.1 to 40 parts by weight per 100 parts by weight of the total amount of flame retardant.

[0069] In the manufacturing method of the present invention, a method for blending a flame retardant or other additives into a base resin can be employed, for example, by feeding a predetermined proportion of the flame retardant or other additives together with the base resin into a feeder provided upstream of the extruder and kneading them in the extruder. Alternatively, a method can be employed in which the flame retardant or other additives are fed into a molten resin from a feeder provided midway through the extruder. Specifically, a method can be employed in which a dry blend of the flame retardant, other additives, and base resin is fed into the extruder and melt-kneaded; a method can be employed in which the flame retardant, other additives, and base resin are kneaded in a kneader or the like and a melt-kneaded mixture is fed into the extruder; or a method can be employed in which a masterbatch is prepared by blending a high concentration of the flame retardant or other additives into the base resin, and the masterbatch is fed into the extruder and melt-kneaded with the base resin. Particularly from the viewpoint of dispersibility, it is preferable to prepare a flame retardant masterbatch and feed it into the extruder. The flame retardant masterbatch is prepared by using a polystyrene resin as the base resin, which has a melt flow rate of approximately 0.5 to 30 g / 10 min at 200°C under a load of 5 kg, and adjusting the masterbatch so that the flame retardant content is 10 to 95 wt %, more preferably 30 to 90 wt %, and even more preferably 50 to 85 wt %.

[0070] <Physical properties of foam board> Next, the extruded polystyrene resin foam board obtained by the production method of the present invention will be described.

[0071] (Apparent density) The apparent density of the foam board of the present invention is 20 kg / m 3 More than 50kg / m 3 or less, preferably 25 kg / m 3 More than 45kg / m 3 More preferably, it is 30 kg / m or less. 3 More than 40kg / m 3 When the apparent density is within the above range, the material has sufficient mechanical strength and is suitable for use as a lightweight heat insulating material.

[0072] (closed cell ratio) The closed cell ratio of the foam board of the present invention is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more. If the closed cell ratio is within this range, the blowing agent is more likely to remain in the cells, allowing the foam board to maintain its high thermal insulation performance for a long period of time. In addition, the foam board can have excellent mechanical strength, such as compressive strength.

[0073] The closed cell percentage of the extruded foam board in this specification is measured in accordance with Procedure C of ASTM-D2856-70 using a Toshiba Beckman Co., Ltd. air comparison hydrometer, Model 930. (A cut sample, without a molded skin, cut into 25 mm x 25 mm x 20 mm pieces from the foam board is placed in a sample cup for measurement. However, if the foam board is too thin to cut a 20 mm cut sample in the thickness direction, for example, two cut samples each measuring 25 mm x 25 mm x 10 mm may be placed in the sample cup at the same time for measurement.) The true volume Vx of the extruded foam board (cut sample) is used to calculate the closed cell percentage S (%) using the following formula (1), and the average value is calculated for N = 3.

[0074] S(%)=(Vx-W / ρ)×100 / (V A -W / ρ) (1) Vx: The true volume (cm) of the cut sample measured by the above method 3 ) (This corresponds to the sum of the volume of the resin that makes up a cut sample of the extruded foam board and the total volume of the air bubbles in the closed cell portion of the cut sample.) V A : 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 resin that makes up the extruded foam board (g / cm 3 )

[0075] (Thermal conductivity after 7 days) The foam board of the present invention preferably has a thermal conductivity of 0.028 W / m·K or less, and more preferably 0.025 W / m·K or less, 7 days after production.

[0076] (Thermal conductivity after 300 days) The foam board of the present invention preferably has a thermal conductivity of 0.030 W / m·K or less, more preferably 0.027 W / m·K or less, 300 days after production.

[0077] The thermal conductivity can be measured based on the heat flow meter method described in JIS A1412-2:1999 (symmetrical construction of one test piece, high temperature side 38°C, low temperature side 8°C, average temperature 23°C).

[0078] (cross-sectional area, dimensions, etc.) The foamed board of the present invention is in the form of a plate, and its cross-sectional area perpendicular to the extrusion direction is 100 cm 2 More than 200cm 2 The upper limit of the cross-sectional area is approximately 1500 cm 2 In this specification, the cross-sectional area perpendicular to the extrusion direction refers to the area of ​​a cross section perpendicular to the extrusion direction of the foam board.

[0079] The foam board of the present invention is usually produced by preparing a base plate one size larger than the desired size, and then cutting the base plate to adjust the width, length, and in some cases the thickness.

[0080] However, if the width of the base plate fluctuates significantly during production and becomes narrower than specified, it becomes impossible to obtain a foamed board of the specified size, resulting in a poor yield. Furthermore, in the production of foamed boards, the lower the apparent density and the larger the cross-sectional area, the more difficult it tends to be to expand. The production method of the present invention has excellent production stability, making it possible to stably produce foamed boards with good appearance, even when producing foamed boards with large thicknesses and cross-sectional areas. Extruded foamed boards with a good foaming state and excellent surface smoothness can be suitably used as foamed boards with a molded skin without cutting the surface in the thickness direction.

[0081] In the case of a foam board used as a thermal insulating material, its thickness is preferably 20 mm or more, more preferably 30 mm or more, and even more preferably 50 mm or more. On the other hand, the upper limit of the thickness is preferably 150 mm, more preferably 130 mm. In the present invention, since the process includes a step of extruding and foaming a foamable molten resin composition into a plate, a foam board can be stably produced even when the thickness is large.

[0082] The width is preferably 800 mm or more, more preferably 900 mm or more, with the upper limit being approximately 1200 mm. [Example]

[0083] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0084] In the examples and comparative examples, the following devices and raw materials were used.

[0085] The extrusion equipment used consisted of a first highly mixed extruder with an inner diameter of 115 mm and a second extruder with an inner diameter of 180 mm connected in series, a physical foaming agent injection port near the end of the first extruder, and a flat die equipped with a resin outlet (die lip) with a rectangular cross section measuring 1 mm and a width of 440 mm, connected to the outlet of the second extruder. A molding device (guider) consisting of a pair of upper and lower polytetrafluoroethylene resin plates placed horizontally at an approximately fixed interval was attached to the resin outlet of the second extruder.

[0086] (1) Base resin The polystyrene resins listed in Table 1 were used. The recycled polystyrene resin composition (RPS1) in Table 1 was prepared by crushing an extruded polystyrene foam board produced under the same conditions as in Example 1, except that the base resin was PS1 (100% by weight). The crushed material was fed into a single-screw extruder with an inner diameter of 90 mm and an L / D ratio of 50 and kneaded at a maximum temperature of 220°C. The molten resin was extruded into strands at a throughput of 250 kg / hr and cut into pellets, yielding pellets of the recycled PS resin composition (RPS1).

[0087] The specific method for determining the melt tension of the polystyrene resin at 200°C in Table 1 was measured using a Capilograph 1D (manufactured by Toyo Seiki Seisakusho, Ltd.) in accordance with ASTM D1238. The specific measurement method is as follows: A cylinder with a diameter of 9.55 mm and a length of 350 mm and an orifice with a nozzle diameter of 2.095 mm and a length of 8.0 mm were used, the cylinder and orifice were set to a temperature of 200°C (MT200), a polystyrene resin sample was placed in the cylinder, and after leaving it for 4 minutes, the piston speed was increased to 10 mm / min and the molten resin was extruded from the orifice in a string-like shape. This string-like material was hung on a tension detection pulley with a diameter of 45 mm, and the string-like material was taken up by a take-up roller while the take-up speed was increased at a constant rate so that it reached 200 m / min from 0 m / min in 4 minutes, and the maximum tension value just before the string-like material broke was obtained. The above procedure was repeated 10 times using different samples. The three largest and three smallest maximum values ​​were removed from the 10 measurements, and the arithmetic mean of the remaining four intermediate maximum values ​​was used as the melt tension (cN). However, if the melt tension was measured using the above method and the string-like material did not break even when the take-up speed reached 200 m / min, the melt tension (cN) value obtained by keeping the take-up speed at a constant 200 m / min was used. Specifically, similar to the above measurement, the molten resin was extruded into a string from the orifice, and this string-like material was hung on a tension detection pulley. The take-up roller was rotated while the take-up speed was increased at a constant rate so that it reached 200 m / min over 4 minutes, and the rotation speed was waited until it reached 200 m / min. Melt tension data collection began after the rotation speed reached 200 m / min, and data collection was completed 30 seconds later. The melt tension in this specification was determined as the average value (Tave) of the maximum tension (Tmax) and the minimum tension (Tmin) obtained from a tension load curve obtained during these 30 seconds, with the melt tension on the vertical axis and the time on the horizontal axis.

[0088] As described above, the MFR (melt flow rate) of the polystyrene resin in Table 1 was measured based on JIS K7210-1:2014 under the conditions of a test temperature of 200°C and a nominal load of 5 kg.

[0089] [Table 1]

[0090] (2) Flame retardants A flame retardant masterbatch (GR-134BG manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) containing a mixed flame retardant of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether): Dai-ichi Kogyo Seiyaku "SR-130" / tetrabromobisphenol A-bis(2,3-dibromopropyl ether): Dai-ichi Kogyo Seiyaku "SR-720" = 60% by weight / 40% by weight was used, and the masterbatch was added so as to obtain the flame retardant amounts shown in Tables 1 and 2.

[0091] (3) Foam adjuster Talc (manufactured by Matsumura Sangyo Co., Ltd., product name "High Filler #12", particle size (d50) 7.5 μm)

[0092] (4) Radiation suppressants (4-1) Graphite (Graphite: manufactured by Resino Color Kogyo Co., Ltd., product name: SBF-T-1683, flake graphite powder, average particle size 17 μm, 40% masterbatch) (4-2) Titanium oxide (manufactured by Nikko Bix Co., Ltd.)

[0093] (5) Physical foaming agents (a) HFO-1336mzz: Mitsui Chemours Fluoroproducts (b) Dimethyl ether: manufactured by Mitsubishi Gas Chemical Company, Inc. (c1) water (c2) Alcohol (ethanol / isopropyl alcohol / 1-propanol = 90% by weight / 6% by weight / 4% by weight): manufactured by Yamaichi Chemical Industry Co., Ltd. (c3) Carbon dioxide: manufactured by Showa Carbonic Co., Ltd.

[0094] Examples 1 to 9, Comparative Examples 1 to 5 The types and amounts of base resin, flame retardant masterbatch, and cell control agent shown in Table 2 (Examples 1 to 9) and Table 3 (Comparative Examples 1 to 5) were fed into a first extruder, heated to 200°C, and kneaded. The types and amounts of physical blowing agents shown in Tables 2 and 3 were fed through a physical blowing agent inlet provided in the first extruder, and further kneaded to form a foamable resin melt. The resulting foamable resin melt was then transferred to a second extruder to adjust the resin temperature, and after that, extruded into a guider at a discharge rate of 400 kg / hr. The melt was passed through the guider while foaming and molded (shaped) into a board-like shape to produce a base plate of foam board 30 mm thick. The width and length of the base plate were adjusted by cutting, and the molding skins on both sides were evenly cut to produce a rectangular parallelepiped polystyrene resin foam board without a molding skin (width: 910 mm, length: 1820 mm, thickness: 25 mm, cross-sectional area perpendicular to the extrusion direction: 227.5 cm). 2 ) was manufactured.

[0095] [Table 2]

[0096] [Table 3]

[0097] The foamed boards obtained under the conditions of the Examples and Comparative Examples were measured for thickness, apparent density, closed cell content, and thermal conductivity (after 7 days and 300 days) using the following methods, and were evaluated for flammability, manufacturing stability, and appearance according to the following criteria. The results are shown in Tables 2 and 3.

[0098] (Thickness) The foamed plate was measured at three positions that divided the plate into four equal parts in the width direction, and the measured values ​​were averaged to obtain the thickness.

[0099] (Apparent density) The apparent density of the foam board was determined as follows: rectangular parallelepiped samples, each 50 mm long x 50 mm wide x 20 mm thick, were cut out from the center and both ends of the foam board at a position that divided the foam board into two equal parts in the length direction, and the weights were measured. The apparent density of each sample was calculated by dividing the weights by the volume, and the arithmetic average of these was used as the apparent density.

[0100] (closed cell ratio) The closed cell ratio of the foam board was calculated from the above formula (1) using the true volume Vx of the foam board measured using an air comparison hydrometer (Toshiba Beckman Co., Ltd., air comparison hydrometer, model: 930) in accordance with procedure C of ASTM-D2856-70.

[0101] (Thermal conductivity: 7 days after manufacture) Test pieces measuring 200 mm long x 200 mm wide x 20 mm thick were cut out from the center of the width direction of the foamed board immediately after production, and the test pieces were stored in a constant temperature and humidity room at a temperature of 23°C and a relative humidity of 50%. Seven days after production, the thermal conductivity of each test piece was measured using the flat plate heat flow meter method described in JIS A1412-2 (1999) (two heat flow meter system, high temperature side 38°C, low temperature side 8°C, average temperature 23°C).

[0102] (Thermal conductivity: 300 days after manufacture) The thermal conductivity 300 days after manufacture was measured on extruded foam boards subjected to Test Method A of the Long-Term Accelerated Test for Thermal Resistance in accordance with JIS A1486:2014. Specifically, a rectangular parallelepiped (200 mm x 200 mm x 25 mm) was cut from the center of the width of the extruded foam board immediately after manufacture, and then uniformly scraped from both sides to cut test pieces (200 mm x 200 mm x 10 mm). These test pieces were stored in a constant temperature and humidity chamber at 23°C and 50% relative humidity. The thermal conductivity of the test pieces 48 days after manufacture (equivalent to 300 days after manufacture of a 25 mm-thick extruded foam board) was measured using the flat plate heat flow meter method (two heat flow meters, high temperature 38°C, low temperature 8°C, average temperature 23°C) described in JIS A1412-2 (1999).

[0103] (flammability) Immediately after production, the foam boards were stored in a constant temperature and humidity room at a temperature of 23°C and a relative humidity of 50%. Four weeks after production, five test pieces (N=5) were randomly cut out from the foam boards. Flammability was measured based on "Test Method A" specified in JIS A9521:2022, a test method for flammability in foam plastic insulation materials, and the flame retardancy of the foam boards was evaluated according to the following criteria. ○: The average burning time of the five test specimens is 3 seconds or less ×: The average burning time of the five test specimens exceeds 3 seconds (not applicable)

[0104] (manufacturing stability) The manufacturing stability was evaluated according to the following criteria. 〇: Continuous and stable extrusion molding into plate shape is possible during extrusion foaming △: Occasional snagging occurred during extrusion foaming, but extrusion molding into a plate was possible ×: Stuckness frequently occurs during extrusion foaming, making it difficult to extrude into a plate shape

[0105] (exterior) The appearance of the base plate and the extruded foam plate was visually evaluated according to the following criteria: The base plate was a foam plate with a molded skin that was one size larger than the desired size, and the extruded foam plate was a foam plate that had been cut to adjust the width, length, and, in some cases, thickness, and had the molded skin removed. ◎: The surfaces of the base plate and extruded foam plate are extremely good ○: The surface of the base plate is slightly rough and has some spot holes. The surface of the extruded foam plate is in excellent condition. △: The surface of the extruded foam board is slightly rough and has some spot holes. ×: Roughness and numerous spot holes on the surface of the extruded foam board

[0106] From the results of the above measurements and evaluations, it was confirmed that Examples 1 to 9, which contain polystyrene resin A, polystyrene resin B, 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz) (blowing agent A), and dialkyl ether having 1 to 3 carbon atoms (blowing agent B) under the conditions of the present invention, are excellent in all of the apparent density, closed cell ratio, thermal conductivity (after 7 days and 300 days), manufacturing stability, and appearance.

[0107] Furthermore, it was confirmed that the appearance was further improved when the ratio of the amount of foaming agent A added to the amount of foaming agent B added was 2 to 3.5.

[0108] In contrast to Examples 1 to 9, Comparative Examples 1 to 5 were unable to improve the apparent density, closed cell content, thermal conductivity of the foam board, manufacturing stability, and appearance. Specifically, these are as follows.

[0109] In Comparative Example 1, the amount of foaming agent A / the amount of foaming agent B did not satisfy the requirements of the present invention. As a result, although a foam board was produced in Comparative Example 1, the foaming property was poor and the production stability and appearance were also poor. In Comparative Example 2, foaming agent B was not used. As a result, in Comparative Example 2, the plasticity was insufficient, foaming was unstable, and it was difficult to produce a foam board. In Comparative Example 3, carbon dioxide was used instead of foaming agent B. As a result, the cells in Comparative Example 3 were too fine, making it difficult to produce a foam board. In Comparative Example 4, a polystyrene-based resin A having a melt tension at 200°C of 7 cN or more and a melt flow rate measured at 200°C under a load of 10 g / 10 min or less was not used. As a result, it was difficult to produce a foam board in Comparative Example 4. In Comparative Example 5, the amount of foaming agent A was set higher than the requirements of the present invention. As a result, in Comparative Example 5, foaming was unstable, making it difficult to produce a foam board.

Claims

1. The method includes a step of extruding and foaming a foamable molten resin composition obtained by kneading a base resin mainly composed of a polystyrene-based resin, a flame retardant, and a physical foaming agent, and molding the extrudate into a plate. ３ More than 50kg / m ３ The following method for producing an extruded polystyrene resin foam board: the polystyrene-based resin comprises a polystyrene-based resin A having a melt tension of 10 cN or more at 200°C and a melt flow rate of 7 g / 10 min or less as measured at 200°C under a load of 5 kg, and a polystyrene-based resin B having a melt tension of less than 10 cN at 200°C and a melt flow rate of more than 7 g / 10 min as measured at 200°C under a load of 5 kg; the weight ratio of the polystyrene-based resin A to the polystyrene-based resin B (polystyrene-based resin A:polystyrene-based resin B) is 25:75 to 90:10, the total amount of the physical foaming agent added is 1 mol or more and 1.8 mol or less per 1 kg of the base resin, the physical blowing agent contains 1,1,1,4,4,4-hexafluoro-2-butene and a dialkyl ether having 1 to 3 carbon atoms; the amount of 1,1,1,4,4,4-hexafluoro-2-butene added is 0.3 mol or more and 1.1 mol or less per 1 kg of the base resin; the amount of the dialkyl ether having 1 to 3 carbon atoms added is 0.05 mol or more and 0.8 mol or less per 1 kg of the base resin; A method for producing an extruded polystyrene resin foam board, characterized in that the ratio of the amount (mol / kg) of 1,1,1,4,4,4-hexafluoro-2-butene added to the amount (mol / kg) of the dialkyl ether having 1 to 3 carbon atoms added is 1 to 10.

2. 2. The method for producing an extruded polystyrene resin foam board according to claim 1, wherein the amount of 1,1,1,4,4,4-hexafluoro-2-butene added is 0.6 mol or more and 0.9 mol or less per 1 kg of the base resin.

3. 3. The method for producing an extruded polystyrene resin foam board according to claim 1, wherein the amount of the dialkyl ether having 1 to 3 carbon atoms added is 0.1 mol or more and 0.6 mol or less per 1 kg of the base resin.

4. 3. The method for producing an extruded polystyrene foam board according to claim 1, wherein the ratio of the amount (mol / kg) of the 1,1,1,4,4,4-hexafluoro-2-butene to the amount (mol / kg) of the dialkyl ether having 1 to 3 carbon atoms is 2 to 3.

5.

5. 3. The method for producing an extruded polystyrene foam board according to claim 1, wherein the polystyrene resin B comprises a polystyrene resin b, and the polystyrene resin b is a recycled raw material derived from scraps of extruded polystyrene foam boards and / or crushed extruded polystyrene foam boards.

6. 3. The method for producing an extruded polystyrene foam board according to claim 1, wherein the thickness of the extruded polystyrene foam board is 20 mm or more.

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