Thermoplastic resin extruded bubble sheet

Abstract

To provide a production method of a thermoplastic resin extruded foam plate having excellent fire retardancy and long-term heat insulation property.SOLUTION: A thermoplastic resin extruded foam plate contains a base resin comprising a styrene-acrylonitrile copolymer and a fire retardant, and has an apparent density of 20 kg / m3 or more and 50 kg / m3 or less, a cross-sectional area perpendicular to the extrusion direction of 100 cm2 or more, and thickness of 20 mm or more and 150 mm or less, wherein the total amount (Ch+Cc) of a content Ch of a hydrofluoroolefin per kg of the thermoplastic resin extruded foam plate measured by gas chromatography using a test piece conditioned in the method (1) and a content Cc (including 0) of a 3-5C aliphatic saturated hydrocarbon per kg of the extruded thermoplastic resin foam plate is 0.5 mol or more and 1.3 mol or less, and a ratio [Ch / (Ch+Cc)] of the content Ch to the total amount (Ch+Cc) is more than 0.5. Method (1): Cut out a test piece, with a 500 mm length, a 200 mm width and a 5 mm thickness, in which no molding skin exists, from the thermoplastic resin extruded foam plate, and carry out conditioning of the test piece by settling the test piece for 37 days under an atmosphere at a temperature of 23°C and humidity of 50%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to thermoplastic resin extruded foam boards, and more specifically, to thermoplastic resin extruded foam boards that can be suitably used as insulation materials for walls, floors, roofs, etc., of buildings. [Background technology]

[0002] Extruded thermoplastic foam boards (hereinafter also simply referred to as "extruded foam boards") are widely used as building insulation materials due to their excellent heat insulation properties and mechanical strength. Extruded foam boards are generally manufactured by heating and melting a thermoplastic resin such as polystyrene in an extruder, then injecting a physical blowing agent into the resulting molten material under pressure and kneading it to obtain a foamed molten resin mixture. This mixture is then extruded into a low-pressure area through a flat die attached to the tip of the extruder to foam it, and finally molded into a board shape using a molding tool.

[0003] In recent years, there has been a growing demand for energy-saving features in homes and buildings, creating a need for extruded foam boards with superior flame retardancy and thermal insulation. One method for manufacturing extruded foam boards with excellent thermal insulation is to use various hydrofluoroolefins (hereinafter also simply referred to as "HFOs") as physical blowing agents. HFOs are non-combustible blowing agents that can impart high thermal insulation properties to extruded foam boards. Furthermore, they are environmentally friendly blowing agents because they have very low ozone depletion potentials and global warming potentials.

[0004] Furthermore, attempts have been made to use styrene-acrylonitrile copolymer as the base resin for extruded foam boards. For example, Patent Document 1 discloses the production of extruded foam boards using styrene-acrylonitrile copolymer as the base resin and 1,3,3,3-tetrafluoropropene (HFO-1234ze) as the HFO. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-94472 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, in the technology described in Patent Document 1, HFO does not easily remain in the extruded foam board, and the HFO content in the extruded foam board may decrease significantly over a long period of time after manufacturing. In other words, there was room for improvement from the viewpoint of achieving good long-term thermal insulation. Taking these circumstances into consideration, the present invention provides a thermoplastic resin extruded foam board that has good flame retardancy and excellent long-term thermal insulation. [Means for solving the problem]

[0007] According to the present invention, the following thermoplastic resin extruded foam board is provided.

[0008] [1] A base resin containing a styrene-acrylonitrile copolymer and a flame retardant, with an apparent density of 20 kg / m³ 3 More than 50kg / m 3 Below, the cross-sectional area perpendicular to the extrusion direction is 100 cm². 2 A thermoplastic resin extruded foam board having a thickness of 20 mm or more and 150 mm or less, wherein the total amount (Ch + Cc) of hydrofluoroolefin content Ch and aliphatic saturated hydrocarbon content Cc (including 0) per 1 kg of the thermoplastic resin extruded foam board, measured by gas chromatography using a test piece conditioned by the following method (1), is 0.5 mol or more and 1.3 mol or less, and the ratio of the content Ch to the total amount (Ch + Cc) [Ch / (Ch + Cc)] is greater than 0.5. Method (1): A test piece measuring 500 mm in length x 200 mm in width x 5 mm in thickness without a molded surface is cut from the thermoplastic resin extruded foam board, and the test piece is conditioned by standing it for 37 days in an atmosphere of 23°C and 50% humidity.

[0009] [2] In the thermoplastic resin extrusion foam board of [1], the molecular weight of the hydrofluoroolefin is 110 or more.

[0010] [3] In the thermoplastic resin extrusion foam board of [1] or [2], the hydrofluoroolefin is one or more selected from the group consisting of 1-chloro-2,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene, and 1,1,1,4,4,4-hexafluoro-2-butene.

[0011] [4] In the thermoplastic resin extrusion foam board according to any one of [1] to [3], the hydrofluoroolefin is 1-chloro-2,3,3,3-tetrafluoropropene.

[0012] [5] In the thermoplastic resin extrusion foam board according to any one of [1] to [4], the content Cc of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms per 1 kg of the thermoplastic resin extrusion foam board is 0.1 mol or more and 0.6 mol or less.

[0013] [6] In the thermoplastic resin extrusion foam board according to any one of [1] to [5], the average cell diameter in the thickness direction of the thermoplastic resin extrusion foam board is 50 μm or more and 300 μm or less.

[0014] [7] In the thermoplastic resin extrusion foam board according to any one of [1] to [6], the content of the acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base resin is 20% by mass or more and 40% by mass or less.

[0015] [8] In the thermoplastic resin extrusion foam board according to any one of [1] to [7], the flame retardant contains a brominated styrene-butadiene copolymer, and the blending amount of the brominated styrene-butadiene copolymer is 0.5 parts by mass or more and 8 parts by mass or less with respect to 100 parts by weight of the base resin.

[0016] [9] In the thermoplastic resin extruded foam board described in [8] above, the flame retardant further comprises brominated bisphenol, wherein the amount of brominated bisphenol is 0.1 parts by mass or more and 1 part by mass or less per 100 parts by mass of the base resin, and the ratio of the amount of brominated bisphenol to the amount of brominated styrene-butadiene copolymer is 0.05 or more and 0.3 or less. [Effects of the Invention]

[0017] The extruded foam board of the present invention exhibits good flame retardancy and excellent long-term heat insulation properties. [Modes for carrying out the invention]

[0018] <Thermoplastic resin extruded foam board> The following describes the thermoplastic resin extruded foam board (hereinafter also referred to as "extruded foam board") according to the present invention. The extruded foam board of the present invention contains a base resin, a physical foaming agent, and a flame retardant, and has an apparent density of 20 kg / m³. 3 More than 50kg / m 3 The following applies, with a cross-sectional area perpendicular to the extrusion direction of 100 cm². 2 The above conditions apply, and the thickness is between 20mm and 150mm.

[0019] The extruded foam board according to the present invention is manufactured in general terms as follows. For example, additives such as a flame retardant and a foam regulator are added to a base resin and supplied to an extruder, where it is heated, melted, and kneaded. Next, a physical foaming agent is injected under pressure into the extruder and kneaded further to form a foamable molten resin composition, and this foamable molten resin composition is extruded from a high-pressure area to a low-pressure area (usually into the atmosphere) to foam it. Then, the resulting foam is shaped into a board using a shaping device (such as a guider) connected to the die outlet of the extruder, thereby manufacturing a thermoplastic resin extruded foam board. As the shaping device, for example, a device consisting of a pair of upper and lower polytetrafluoroethylene plates is used. Details of the manufacturing method of the extruded foam board will be described later.

[0020] [Base resin] The extruded foam board of the present invention contains a styrene-acrylonitrile copolymer as a base resin. Specifically, it is preferable that 50% by mass or more of the base resin is a styrene-acrylonitrile copolymer, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, 100% by mass, that is, it is most preferable that the base resin is substantially composed solely of a styrene-acrylonitrile copolymer.

[0021] A styrene-acrylonitrile copolymer is a copolymer of styrene and acrylonitrile. The styrene-acrylonitrile copolymer may consist of one type, or it may contain two or more types with different copolymerization ratios of styrene and acrylonitrile.

[0022] The content of acrylonitrile components derived from the styrene-acrylonitrile copolymer in the base resin is, for example, 10% by mass or more and 40% by mass or less.

[0023] From the viewpoint of further improving the persistence of hydrofluoroolefins in extruded foam boards, the content of acrylonitrile components derived from styrene-acrylonitrile copolymer in the base resin is preferably 15% by mass or more, and more preferably 20% by mass or more.

[0024] From the viewpoint of further improving the surface properties of the resulting extruded foam board, the content of acrylonitrile component in the base resin is preferably 35% by mass or less, and more preferably 30% by mass or less.

[0025] When two or more styrene-acrylonitrile copolymers with different acrylonitrile content are used, the amount of acrylonitrile component derived from the styrene-acrylonitrile copolymer in the entire base resin is calculated according to the amount (mass%) of each styrene-acrylonitrile copolymer in the base resin and the amount (mass%) of the acrylonitrile component in each styrene-acrylonitrile copolymer. For example, if the base resin is composed of 40% by mass of a styrene-acrylonitrile copolymer with an acrylonitrile component content of 50% by mass and 60% by mass of a styrene-acrylonitrile copolymer with an acrylonitrile component content of 20% by mass, the amount of acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base resin is 40% by mass × 0.5 + 60% by mass × 0.2 = 32% by mass.

[0026] The acrylonitrile content in styrene-acrylonitrile copolymer can be determined by pyrolysis gas chromatography analysis.

[0027] The base resin according to the present invention may contain other polymers besides styrene-acrylonitrile copolymer, to the extent that the objectives and effects of the present invention are achieved. Examples of other polymers include thermoplastic resins such as polystyrene resins, polypropylene resins, polyester resins, polyolefin resins, polyphenylene ether resins, and polymethyl methacrylate, as well as thermoplastic elastomers such as styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer hydrogenated, styrene-isoprene-styrene block copolymer hydrogenated, and styrene-ethylene copolymer. However, the content of other polymers is preferably less than 30% by mass, more preferably 20% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 0% by mass, meaning the base resin contains only styrene-acrylonitrile copolymer as a polymer component.

[0028] The melt viscosity of the base resin used in the extruded foam board of the present invention is preferably 500 Pa·s to 4000 Pa·s, more preferably 1000 Pa·s to 3700 Pa·s, and even more preferably 1200 Pa·s to 3000 Pa·s, due to its excellent foaming properties and moldability. In this specification, the melt viscosity is based on JIS K7199:1999, at a temperature of 200°C and a shear rate of 100 sec. -1 These are values ​​measured under the following conditions.

[0029] [Physical foaming agent] The physical blowing agent used in the present invention includes hydrofluoroolefins (hereinafter also referred to as "HFO"). Hydrofluoroolefins (HFOs) are fluorine-containing hydrocarbons having a structure in which at least one hydrogen atom and one fluorine atom are bonded to a carbon skeleton with unsaturated bonds. For example, a hydrofluoroolefin may have a structure in which one hydrogen atom and one fluorine atom are bonded to a carbon skeleton with unsaturated bonds. In addition to hydrogen and fluorine atoms, a chlorine atom may also be bonded to the carbon skeleton of a hydrofluoroolefin. That is, the term hydrofluoroolefin in this specification is a concept that includes hydrochlorofluoroolefins (HCFOs) having a structure in which one hydrogen atom, one fluorine atom and one chlorine atom are bonded to a carbon skeleton with unsaturated bonds.

[0030] The HFO includes one or more selected from 1,3,3,3-tetrafluoropropene (hereinafter also referred to as "HFO-1234ze"), 1-chloro-3,3,3-trifluoropropene (hereinafter also referred to as "HFO-1233zd"), 1-chloro-2,3,3,3-tetrafluoropropene (hereinafter also referred to as "HFO-1224yd"), 2,3,3,3-tetrafluoropropene (hereinafter also referred to as "HFO-1234yf"), 1,1,1,4,4,4-hexafluoro-2-butene (hereinafter also referred to as "HFO-1336mzz"), etc. Hydrofluoroolefins have a zero ozone depletion potential, a very low global warming potential, low thermal conductivity in the gaseous state, and are non-flammable.

[0031] In particular, it is preferable to include HFO with a molecular weight of 110 or more as a physical blowing agent. By including HFO with a molecular weight of 110 or more, compared to the case where HFO with a molecular weight of less than 110 is included, the HFO is more likely to remain in the extruded foam board using styrene-acrylonitrile copolymer as the base resin, and the long-term thermal insulation properties of the extruded foam board can be improved. When two or more HFOs with different molecular weights are included, it is preferable that the proportion of HFO with a molecular weight of 110 or more accounts for 60 mol% or more of 100 mol%, more preferably 80 mol% or more, and even more preferable that it contains only 100 mol%, i.e., HFO with a molecular weight of 110 or more.

[0032] Furthermore, in extruded foam boards using styrene-acrylonitrile copolymer as the base resin, HFO tends to remain more readily, and the long-term thermal insulation properties of the extruded foam boards can be improved. Therefore, it is more preferable that the HFO contains one or more selected from the group consisting of 1-chloro-2,3,3,3-tetrafluoropropene (HFO-1224yd), 1-chloro-3,3,3-trifluoropropene (HFO-1233zd), and 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz). Among these, HFO-1224yd is preferred. By including HFO-1224yd as the HFO, even when the HFO content Ch per 1 kg of the extruded foam board, as described later, is relatively high, for example, 0.5 mol or more, the decrease in the heat resistance of the extruded foam board is suppressed.

[0033] The HFO content (Ch) per 1 kg of extruded foam board is, for example, 0.25 mol or more, and 0.3 mol or more. Keeping the Ch content within the above range ensures good long-term thermal insulation of the extruded foam board.

[0034] Furthermore, from the viewpoint of more reliably increasing the long-term thermal conductivity of the extruded foam board, the HFO content Ch per 1 kg of extruded foam board is preferably 0.5 mol or more, more preferably 0.55 mol or more, and even more preferably 0.6 mol or more. When manufacturing the extruded foam board according to the present invention, for example, by blending the above-mentioned base resin with a predetermined amount of HFO, it becomes possible to retain HFO in the obtained extruded foam board at such a high content as described above.

[0035] On the other hand, from the viewpoint of more reliably suppressing the occurrence of gas spots which degrade the appearance of the extruded foam board and reduce its heat resistance, the HFO content Ch per 1 kg of extruded foam board is preferably 1.3 mol or less, 1.1 mol or less, and more preferably 1.0 mol or less.

[0036] The physical blowing agent may include other physical blowing agents besides HFO, as long as they do not hinder the objectives and effects of the present invention.

[0037] Other examples of physical blowing agents include water, alcohol, aliphatic saturated hydrocarbons with 3 to 5 carbon atoms, dialkyl ethers with 1 to 3 carbon atoms (e.g., dimethyl ether and diethyl ether), and carbon dioxide.

[0038] From the viewpoint of increasing the compressive strength of the resulting extruded foam board, it is preferable to include aliphatic saturated hydrocarbons having 3 to 5 carbon atoms among the other physical blowing agents exemplified above. As aliphatic saturated hydrocarbons having 3 to 5 carbon atoms, one or more selected from propane, n-butane, isobutane (2-methylpropane), n-pentane, isopentane (2-methylbutane), cyclobutane, neopentane (2,2-dimethylpropane), cyclopentane, etc., can be used in mixtures. Among these, isobutane can be preferably used.

[0039] The content of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms (Cc) per 1 kg of extruded foam board is preferably, for example, 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. When the content of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms (Cc) is within the above range, the compressive strength of the extruded foam board can be improved.

[0040] The total amount of hydrofluoroolefin (Ch) and aliphatic saturated hydrocarbons with 3 to 5 carbon atoms (Cc) per 1 kg of extruded foam board (Ch + Cc) is between 0.5 mol and 1.3 mol, and the ratio of Ch to the total amount (Ch + Cc) [Ch / (Ch + Cc)] is greater than 0.5. Having both the total amount (Ch + Cc) and the ratio [Ch / (Ch + Cc)] within the above range ensures good long-term thermal insulation of the extruded foam board.

[0041] In addition, in the extruded foam board of the present invention, the content Cc of one or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms may be 0. In this case, the total amount (Ch + Cc) corresponds to the content Ch, and the ratio [Ch / (Ch + Cc)] is 1.

[0042] From the viewpoint of suppressing the increase in thermal conductivity of extruded foam boards over long periods of time and further improving their heat insulation properties, the total amount (Ch + Cc) is preferably 0.52 mol or more, more preferably 0.55 mol or more, and even more preferably 0.6 mol or more per 1 kg of extruded foam board.

[0043] From the viewpoint of more reliably suppressing the risk of numerous gas spots forming on the resulting extruded foam board, which may degrade the appearance of the extruded foam board, and the risk of a decrease in the heat resistance of the extruded foam board, the total amount (Ch + Cc) is preferably 1.1 mol or less, more preferably 1.0 mol or less, and even more preferably 0.8 mol or less, per kg of the extruded foam board.

[0044] From the viewpoint of more reliably suppressing the increase in thermal conductivity of extruded foam boards over long periods of time and obtaining higher flame retardancy, the ratio [Ch / (Ch+Cc)] is preferably 0.55 or higher, more preferably 0.6 or higher, even more preferably 0.75 or higher, particularly preferably 0.9 or higher, and most preferably 1, that is, it is free from 1 or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms.

[0045] In this specification, the content of physical blowing agents (HFO, aliphatic saturated hydrocarbons) in extruded foam boards is a value measured by the following method using gas chromatography. Specifically, a test piece measuring 500 mm in length, 200 mm in width, and 5 mm in thickness, without a molded surface, is cut from the center of the extruded foam board, and the test piece is conditioned by standing in an atmosphere of 23°C and 50% humidity for 37 days. In this specification, this conditioning method is referred to as method (1). A sample weighing 1 g is cut from the test piece conditioned by method (1), and the content of HFO and aliphatic saturated hydrocarbons in the extruded foam board is measured by gas chromatography analysis. The content of physical blowing agents obtained in a 37-day accelerated test with a test piece thickness of 5 mm corresponds, for example, to the content of physical blowing agents in an extruded foam board with a thickness of 50 mm approximately 10 years after manufacture.

[0046] Gas chromatographic analysis is performed as follows: The above sample is accurately weighed and placed in a sealed sample bottle containing 50 mL of toluene solution (containing approximately 0.02 g of accurately weighed cyclopentane as an internal standard). The bottle is immediately sealed, and the mixture is thoroughly stirred to dissolve the physical foaming agent in the sample into the toluene, which is then used as the measurement sample. Approximately 2 μL of this solution is taken using a microsyringe and injected into the gas chromatograph to obtain a chromatogram.

[0047] The measurement conditions for the gas chromatograph are as follows: Equipment used: GC-14B manufactured by Shimadzu Corporation Column: Glass column for Shimadzu GC-14B, manufactured by Shinwa Chemical Co., Ltd. • Packed column: Glass column, 4.1m length x 3.2mm inner diameter ·Stationary phase: Silicone DC550 20% • Carrier: Chromosorb W AW DMCS (60 / 80 mesh) Column temperature: 40℃ Detector: FID Carrier gas: Nitrogen Carrier gas flow rate: 50 mL / min Inlet temperature: 200℃ Detector temperature: 200℃ From the obtained gas chromatogram, the peak area of ​​each physical blowing agent component is read, and the HFO content and isobutane content are calculated using an internal standard and a calibration curve of the relative sensitivity of each blowing agent component.

[0048] The measurement of the physical blowing agent content (residual amount) described above is preferably performed on extruded foam boards immediately after manufacturing (for example, within 24 hours after manufacturing). Note that the physical blowing agent content does not fluctuate significantly within a range of, for example, 10 years ± 1 year after manufacturing. Therefore, the physical blowing agent content may be measured using the above method for extruded foam boards regardless of the time elapsed since manufacturing.

[0049] In the present invention, as described above, by using a specific resin in which the acrylonitrile component content is adjusted to a predetermined range as the base resin and blending it with HFO as a physical foaming agent to manufacture an extruded foam board, the amount of HFO remaining in the resulting extruded foam board is maintained at a high level over a long period of time. In other words, it is characterized by a high HFO retention rate Rh in the extruded foam board. The HFO retention rate Rh in the extruded foam board is expressed by the following formula (1). Rh = Ch / Bh × 100 ... (1)

[0050] Here, Bh is the amount of HFO added per 1 kg of the extruded foam board (mol / kg) during the manufacturing of the extruded foam board, and Ch is the HFO content in 1 kg of the extruded foam board (mol / kg), which is a value obtained by accelerated testing using the method (1) described above. In the extruded foam board obtained by the present invention, the remaining HFO percentage Rh in the extruded foam board is preferably 65% ​​or more, more preferably 70% or more, and even more preferably 75% or more. There is no particular upper limit to the remaining HFO percentage Rh in the extruded foam board, but it is generally around 90%.

[0051] Furthermore, when the physical blowing agent contains one or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms, the ratio of the remaining rate Rh of HFO in the extruded foam board to the remaining rate Rc of one or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms in the extruded foam board (Rh / Rc) is preferably 0.8 or higher, more preferably 0.85 or higher, and even more preferably 0.9 or higher. The remaining rate Rc of one or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms in the extruded foam board is expressed by the following formula (2). Rc = Cc / Bc × 100 ... (2)

[0052] Here, Bc is the amount (mol / kg) of one or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms added per 1 kg of the extruded foam board during its manufacture, and Cc is the content (mol / kg) of one or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms in 1 kg of the extruded foam board, and is a value obtained by accelerated testing using the method (1) described above.

[0053] [Radiation suppressant] In the extruded foam board of the present invention, graphite may be included as a radiation suppressor to improve thermal insulation. Including graphite as a radiation suppressor can enhance the effect of improving thermal insulation.

[0054] Examples of graphite include flake graphite, scaly graphite, artificial graphite, and clay-like graphite, with the use of graphite whose main component is flake graphite being preferable. It is preferable to add the graphite as a masterbatch blended at a high concentration into the base resin. Graphite with a fixed carbon content of 80% or more is preferable because it offers good workability during masterbatch production and excellent thermal insulation improvement of the resulting extruded foam board. Furthermore, to further enhance the thermal insulation of the extruded foam board, graphite with a fixed carbon content of 90% or more is more preferable, and 95% or more is even more preferable. The upper limit of the fixed carbon content is approximately 100%. The fixed carbon content of graphite refers to the value measured according to the method compliant with JIS M8511:2014.

[0055] When graphite is included, the graphite content is, for example, 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the base resin. When the amount of graphite added is within the above range, the radiation suppression effect of graphite is more easily exhibited. In addition, it is possible to suppress an excessive decrease in the apparent density of the extruded foam board and deterioration of the surface condition. From the viewpoint of more reliably exhibiting the above effects, it is more preferable that the amount of graphite added is 0.3 parts by mass or more, and even more preferable that it is 0.5 parts by mass or more, per 100 parts by mass of the base resin. On the other hand, the upper limit of the amount of graphite added is more preferably 3 parts by mass, and even more preferably 1 part by mass, per 100 parts by mass of the base resin.

[0056] Furthermore, the extruded foam board of the present invention may contain radiation suppressants other than graphite to further improve its heat insulation properties. Examples of radiation suppressants other than graphite include one or more selected from metal oxides such as titanium oxide, metals such as aluminum, ceramics, carbon black, infrared shielding pigments, hydrotalcite, etc. Among these, titanium oxide can be suitably used. The content of radiation suppressants other than graphite is preferably, for example, 0.5 parts by mass or more and 5 parts by mass or less, and preferably 1 part by mass or more and 4 parts by mass or less, per 100 parts by mass of the base resin.

[0057] [Flame retardant] The extruded foam board of the present invention is primarily used as an insulating material for building materials, and its flame retardancy is imparted by the inclusion of a flame retardant in the base resin.

[0058] The amount of flame retardant added is preferably 0.5 parts by mass to 8 parts by mass per 100 parts by mass of the base resin, more preferably 2 parts by mass to 7 parts by mass, and even more preferably 2.5 parts by mass to 6 parts by mass, since this allows for the imparting of high flame retardancy to the extruded foam board while suppressing a decrease in foaming properties and mechanical properties. If the amount of flame retardant is within the above range, it is possible to obtain an extruded foam board that has high flame retardancy, such as the flammability standard for extruded polystyrene foam insulation materials described in "Test Method A" of the flammability test method of JIS A9521:2017, without the flame retardant inhibiting foaming properties.

[0059] The flame retardant used in the present invention is not particularly limited, but it is preferable to use a brominated flame retardant. Examples of brominated flame retardants include brominated butadiene polymers such as brominated styrene-butadiene copolymer, 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), and tetrabromobisphenol-S-bis One or more of the following can be used in combination: brominated bisphenol compounds such as (2,3-dibromopropyl ether) and tetrabromobisphenol-F-bis(2,3-dibromopropyl ether), tris(2,3-dibromopropyl) isocyanurate, mono(2,3,4-tribromobutyl) isocyanurate, di(2,3,4-tribromobutyl) isocyanurate, and tris(2,3,4-tribromobutyl) isocyanurate. From the viewpoint of improving flame retardancy, it is preferable that the flame retardant is a brominated styrene-butadiene copolymer. In particular, it is preferable that the main component of the flame retardant is a brominated styrene-butadiene copolymer. The main component of the flame retardant is a brominated styrene-butadiene copolymer, meaning that the content of the brominated styrene-butadiene copolymer in the flame retardant is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The upper limit of the content of the brominated styrene-butadiene copolymer in the flame retardant is not particularly limited and may be 100% by mass.

[0060] From the viewpoint of improving flame retardancy, the amount of brominated styrene-butadiene copolymer blended is preferably 0.5 parts by mass to 8 parts by mass per 100 parts by mass of the base resin, more preferably 1 part by mass to 6 parts by mass, and even more preferably 2 parts by mass to 5 parts by mass.

[0061] In extruded foam boards using styrene-acrylonitrile copolymer as the base resin, when brominated styrene-butadiene copolymer is used as the flame retardant, it may be difficult to achieve the desired flame retardancy. In the extruded foam board of the present invention, as described above, good flame retardancy can be achieved even when brominated styrene-butadiene copolymer is used as the flame retardant. The reason for this is not clear, but one possible reason is that a relatively large amount of hydrofluoroolefin is contained as a physical blowing agent.

[0062] Furthermore, from the viewpoint of more stably exhibiting flame retardancy when using brominated styrene-butadiene copolymer as a flame retardant, it is preferable to include a brominated bisphenol flame retardant such as tetrabromobisphenol A-bis(2,3-dibromopropyl ether) or tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) in addition to the brominated styrene-butadiene copolymer. Considering the above circumstances, it is preferable that the flame retardant contains both brominated styrene-butadiene copolymer and brominated bisphenol.

[0063] From the viewpoint of improving flame retardancy without impeding moldability, the amount of brominated bisphenol-based flame retardant blended is preferably 0.1 parts by mass or more and 1 part by mass or less per 100 parts by mass of the base resin, more preferably 0.2 parts by mass or more and less than 1 part by mass, and even more preferably 0.3 parts by mass or more and 0.9 parts by mass or less. Also, from the same viewpoint, the ratio of the blended content of brominated bisphenol to the blended content of brominated styrene-butadiene copolymer (brominated bisphenol content / brominated styrene-butadiene copolymer content) is preferably 0.05 or more and 0.3 or less, and more preferably 0.1 or more and 0.25 or less.

[0064] In addition to brominated flame retardants, one or more of the following may be used in combination: cresyldi-2,6-xylenyl phosphate, antimony trioxide, antimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, pentabromottoluene, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, melamine, melam, melem, and other nitrogen-containing cyclic compounds; silicone compounds; inorganic compounds such as boron oxide, zinc borate, and zinc sulfide; phosphate esters represented by triphenyl phosphate; red phosphorus compounds; phosphorus compounds such as ammonium polyphosphate, phosphazene, and hypophosphate.

[0065] [Flame retardant] Furthermore, the extruded foam board of the present invention may contain a flame retardant additive in combination with the flame retardant for the purpose of further improving flame retardancy. Examples of flame retardant additives 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, as well as polyalkylated aromatic compounds such as poly-1,4-diisopropylbenzene. The amount of flame retardant additive is preferably, for example, 0.01 parts by mass or more and 1 part by mass or less, and preferably 0.05 parts by mass or more and 0.5 parts by mass or less, per 100 parts by mass of the base resin.

[0066] Furthermore, the extruded foam board of the present invention may optionally contain other known additives in the base resin. Examples of other additives include foam regulators, colorants such as pigments and dyes, heat stabilizers, fillers, and various other additives.

[0067] [Bubble regulator] In the extruded foam board of the present invention, it is preferable to contain a cell regulator. As the cell regulator, inorganic powder such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, clay, aluminum oxide, bentonite, and diatomaceous earth can be used. Among them, talc is suitable because it is easy to adjust the cell diameter and can easily reduce the cell diameter without inhibiting the flame retardancy. Particularly, fine talc with a 50% particle size (photo-transmission centrifugal sedimentation method) of 0.1 μm or more and 20 μm or less is preferable, and fine talc with a 50% particle size of 0.5 μm or more and 15 μm or less is more preferable. The addition amount of the cell regulator varies depending on the type of the regulator, the target cell diameter, etc. When using talc as the cell regulator, the content of talc is preferably 0.1 part by mass or more and 7 parts by mass or less, more preferably 0.2 part by mass or more and 5 parts by mass or less, and still more preferably 0.3 part by mass or more and 3 parts by mass or less per 100 parts by mass of the base resin.

[0068] [Heat stabilizer] The heat stabilizer can improve the thermal stability of the brominated flame retardant by blending it with raw materials, end materials, etc. when manufacturing the extruded foam board or recycling and pelletizing the end materials of the extruded foam board. Examples of the heat stabilizer include bisphenol-type epoxy compounds such as the EPICLON series manufactured by DIC Corporation, novolac-type epoxy compounds, 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 addition amount of the heat stabilizer is preferably 0.1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the total amount of the flame retardant.

[0069] [Apparent density] The apparent density of the extruded foam board according to the present invention is, for example, 20 kg / m 3 or more and 50 kg / m 3 or less, preferably 20 kg / m 3 or more and 45 kg / m 3 or less, and more preferably 25 kg / m3 More than 40kg / m 3 The following applies: When the apparent density is within the above range, it can be suitably used as a thermal insulation material that has sufficient mechanical strength and excellent lightweight properties.

[0070] Apparent density was measured in accordance with JIS K6767 (1999). Rectangular samples measuring 50 mm (length) x 50 mm (width) x 50 mm (thickness) were cut from three locations: the center and near both ends of each extruded foam board in the width direction. The apparent density of each sample was measured, and the arithmetic mean of the three measurements was taken as the apparent density.

[0071] [Closed cell ratio] The closed-cell ratio of the extruded foam board is, for example, 85% or more, preferably 90% or more, and preferably 93% or more. If the closed-cell ratio is within the above range, the foaming agent is more likely to remain in the cells, and the extruded foam board can maintain high thermal insulation performance over a long period of time.

[0072] In this specification, the closed-cell ratio of extruded foam board is determined using the true volume Vx of the extruded foam board (cut sample) measured using the following formula (3), and the closed-cell ratio S (%) is calculated using the average value for N=3. This is done by placing a cut sample without a molded surface, cut to a size of 25 mm × 25 mm × 20 mm from the extruded foam board, into a sample cup for measurement. However, if the thickness is thin and a cut sample of 20 mm in the thickness direction cannot be cut, for example, two cut samples of size 25 mm × 25 mm × 10 mm may be placed simultaneously into the sample cup for measurement.

[0073] S(%)=(Vx-W / ρ)×100 / (V A -W / ρ)···(3) Vx: True volume (cm³) of the cut sample measured by the method described above. 3 (This corresponds to the sum of the volume of resin constituting the cut sample of the extruded foam board and the total volume of the closed-cell portions within the cut sample.) V A : The apparent volume (cm³) of the cut sample calculated from the external dimensions of the cut sample used for measurement. 3 ) W: Total mass (g) of the cut sample used for measurement ρ: Density of the resin constituting the extruded foam board (g / cm³) 3 )

[0074] [Average bubble diameter in the thickness direction] From the viewpoint of further suppressing the emission of hydrofluoroolefins from the extruded foam board, the average cell diameter in the thickness direction is preferably 50 μm or more, more preferably 80 μm or more. On the other hand, from the viewpoint of further improving thermal insulation by suppressing radiant heat transfer, the average cell diameter in the thickness direction is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less.

[0075] The method for measuring the average bubble diameter in the thickness direction is as follows: The average bubble diameter in the thickness direction can be obtained by taking magnified photographs at three locations: the center and near both ends of the cross-section perpendicular to the width direction of the extruded foam board. The magnification is adjusted within a range of 50 to 200 times so that the number of cells in the photograph is approximately 200 to 500. On each photograph, the maximum diameter of individual bubbles in the thickness direction is measured using the image processing software NS2K-pro manufactured by Nano System Co., Ltd., and the average of these values ​​is calculated by taking the arithmetic mean of each value.

[0076] [Bubble deformation rate] Furthermore, in the case of extruded foam boards, it is preferable that the cell deformation rate is between 0.7 and 1.5. The cell deformation rate is calculated by taking the average cell diameter in the thickness direction, obtained by the measurement method described above, measuring the maximum diameter in the width direction of each cell using the image processing software NS2K-pro manufactured by Nano System Co., Ltd. on magnified photographs of the cells, and taking the arithmetic mean of these values ​​to obtain the average cell diameter in the width direction, and then dividing the average cell diameter in the thickness direction by the average cell diameter in the width direction. The smaller the cell deformation rate is than 1, the flatter the cell, and the larger the rate is than 1, the more elongated the cell. When the cell deformation rate is within the above range, the extruded foam board has excellent mechanical strength and higher thermal insulation properties. In addition, the shrinkage of the extruded foam board is more easily suppressed, resulting in an extruded foam board with superior dimensional stability. From the viewpoint of dimensional stability of the extruded foam board, the lower limit of the cell deformation rate is more preferably 0.8. The upper limit of the cell deformation rate is more preferably 1.3, and even more preferably 1.2, from the viewpoint of improving thermal insulation properties.

[0077] [Shape, cross-sectional area, and dimensions] The extruded foam board of the present invention is in the form of a board. The cross-sectional area perpendicular to the extrusion direction in the extruded foam board is 100 cm². 2 That's all, 200cm 2 Preferably, it should be 300 cm or more. 2 It is more preferable that it be greater than or equal to 400 cm. 2 It is even more preferable that the above is true. The upper limit of the cross-sectional area perpendicular to the extrusion direction is approximately 1500 cm². 2 In this specification, the cross-sectional area perpendicular to the extrusion direction refers to the area of ​​the cross-section of the extruded foam board that is perpendicular to the extrusion direction.

[0078] In the case of extruded foam board used as thermal insulation, the thickness of the extruded foam board 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 of the extruded foam board is generally around 150 mm.

[0079] Furthermore, the width of the extruded foam board is preferably 800 mm or more, and more preferably 900 mm or more. The upper limit of the width of the extruded foam board is approximately 1200 mm.

[0080] [Thermal conductivity] The thermal conductivity of the extruded foam board is, for example, 0.028 W / m·K or less, preferably 0.027 W / m·K or less, and more preferably 0.026 W / m·K or less. The method for measuring the thermal conductivity in this invention is as follows.

[0081] The thermal conductivity of the present invention is measured by the following method, which conforms to the accelerated test described in ISO 11561, except for changing the thickness of the test specimen. This standard determines the long-term change in thermal conductivity due to the release of foaming agent from extruded foam board by accelerated testing. Specifically, it is as follows: First, a test specimen is obtained from the extruded foam board by the following method (Method (1)). A test specimen measuring 500 mm in length, 200 mm in width, and 5 mm in thickness, without a molded surface, is cut from the center of the extruded foam board, and the test specimen is conditioned by being left undisturbed for 37 days in an atmosphere of 23°C and 50% humidity. Then, the thermal conductivity is measured using the test specimen obtained by the above method based on the flat plate heat flow meter method (two heat flow meters, high temperature side 38°C, low temperature side 8°C, average temperature 23°C) described in JIS A1412-2:1999.

[0082] In the accelerated testing described in ISO 11561, the specimen thickness is 6 mm or more, but in this invention, for convenience, the specimen thickness was set to 5 mm. The thermal conductivity obtained from a 37-day accelerated testing using a specimen thickness of 5 mm corresponds, for example, to the thermal conductivity of an extruded foam board with a thickness of 50 mm approximately 10 years after manufacturing.

[0083] [Rate of dimensional change] The dimensional change rate of the extruded foam board after heating in a 75°C atmosphere for 22 hours is preferably within ±1%. Specifically, when the dimension of the extruded foam board after heating in a 75°C atmosphere for 22 hours is Da, and the dimension of the extruded foam board before heating is Db, the dimensional change rate of the extruded foam board after heating [(Da-Db) / Db×100] is preferably within ±1%. It is preferable that the dimensional change rate of the extruded foam board when heated in a 75°C atmosphere for 22 hours is within ±1% in each of the thickness, width, and length directions. Note that the dimensional change rate refers to the change in dimensions due to shrinkage and expansion due to heating. If the dimensional change rate of the extruded foam board at 75°C is within the above range, it can be said that the heat resistance is particularly good. More preferably, the dimensional change rate of the extruded foam board at 75°C is within ±0.8%.

[0084] The dimensional change rate can be determined by the following method. Specifically, first, the extruded foam board is left to stand for 12 hours in an environment of 23°C. After standing, a test piece without a skin surface is cut from the extruded foam board with dimensions of 25 mm in the thickness direction, 100 mm in the extrusion direction, and 100 mm in the width direction. The dimensions Db in each direction (VD, MD, TD) of the cut test piece are measured. VD is the thickness direction, MD is the extrusion direction, and TD is the width direction. Then, the test piece is placed in an oven adjusted to a predetermined temperature (75°C), and after 22 hours, the test piece is removed and the dimensions Da in each direction (VD, MD, TD) are measured. The dimensional change rate [(Da-Db) / Db×100] for each direction is then calculated. The largest value among the obtained dimensional change rates in each direction is taken as the dimensional change rate of the extruded foam board after heating in a 75°C atmosphere for 22 hours.

[0085] <Method for manufacturing thermoplastic extruded foam boards> The following describes in detail an example of a method for manufacturing the thermoplastic resin extruded foam board of the present invention. The method for manufacturing the thermoplastic resin extruded foam board (hereinafter also simply referred to as "extruded foam board") according to the present invention includes, for example, a step of extruding a foamable molten resin composition containing a base resin, a flame retardant, and a physical blowing agent, and forming it into a board shape using a molding tool, with an apparent density of 20 kg / m³.3 More than 50kg / m 3 The following applies, with a cross-sectional area perpendicular to the extrusion direction of 100 cm². 2 The above describes a method for producing a thermoplastic resin extruded foam board with a thickness of 20 mm to 150 mm. However, the method for producing the extruded foam board of the present invention is not limited to the following examples.

[0086] In general terms, the manufacturing method of the present invention involves, for example, adding additives such as a flame retardant and a foam regulator to a base resin, supplying it to an extruder, and heating and kneading it. Next, a physical foaming agent is injected under pressure into the extruder and kneaded further to form a foamable molten resin composition, and this foamable molten resin composition is extruded from a high-pressure area to a low-pressure area (usually into the atmosphere) to foam it. Then, the resulting foam is shaped into a plate using a shaping device (such as a guider) connected to the die outlet of the extruder, thereby producing a thermoplastic resin extruded foam sheet. As the shaping device, for example, a device consisting of a pair of upper and lower polytetrafluoroethylene plates can be used. As the base resin, the aforementioned materials can be used.

[0087] [Physical foaming agent] The physical blowing agent used in this invention can be one of those described above. The amount Ah of HFO blended per 1 kg of base resin is, for example, 0.4 mol or more and 1.3 mol or less. By setting the amount Ah of HFO blended within the above range, the residual amount Ch of HFO in the resulting extruded foam board can be increased. Consequently, an extruded foam board with excellent long-term thermal insulation properties can be obtained.

[0088] From the viewpoint of further improving the long-term thermal insulation properties of the resulting extruded foam board, the blending amount Ah is preferably 0.45 mol or more, more preferably 0.5 mol or more, even more preferably 0.6 mol or more, and particularly preferably 0.7 mol or more.

[0089] On the other hand, from the viewpoint of more reliably suppressing the risk of numerous gas spots forming, which could lead to a deterioration in the appearance of the extruded foam board or a decrease in heat resistance, the blending amount Ah is preferably 1.1 mol or less, more preferably 1.0 mol or less, and even more preferably 0.9 mol or less.

[0090] The proportion of HFO in the total amount of physical blowing agent (100 mol%) is, for example, 25 mol% or more, preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 50 mol% or more, and particularly preferably 55 mol% or more, from the viewpoint of improving thermal insulation. The upper limit of the amount of HFO in the total amount of physical blowing agent (100 mol%) may be 100 mol%, but from the viewpoint of more reliably suppressing gas spots, it is preferably 80 mol%, and more preferably 70 mol%.

[0091] The physical blowing agent may include other physical blowing agents besides HFO, as long as they do not hinder the objectives and effects of the present invention.

[0092] Other examples of physical blowing agents include water, alcohol, aliphatic saturated hydrocarbons with 3 to 5 carbon atoms, dialkyl ethers with 1 to 3 carbon atoms (e.g., dimethyl ether and diethyl ether), and carbon dioxide.

[0093] From the viewpoint of increasing the compressive strength of extruded foam boards, it is preferable to use aliphatic saturated hydrocarbons having 3 to 5 carbon atoms among the other physical blowing agents exemplified above. As aliphatic saturated hydrocarbons having 3 to 5 carbon atoms, for example, one or more selected from propane, n-butane, isobutane (2-methylpropane), n-pentane, isopentane (2-methylbutane), cyclobutane, neopentane (2,2-dimethylpropane), cyclopentane, etc., can be used in mixtures. Among these, isobutane can be preferably used.

[0094] The amount of aliphatic saturated hydrocarbon (Ac) with 3 to 5 carbon atoms blended per 1 kg of base resin is preferably, for example, 0.1 mol to 0.6 mol, and more preferably 0.2 mol to 0.5 mol. By keeping the amount of Ac within the above range, the compressive strength of the extruded foam board can be increased.

[0095] It is preferable that the sum of the amount of HFO (Ah) blended per 1 kg of base resin and the amount of aliphatic saturated hydrocarbon (Ac) with 3 to 5 carbon atoms blended per 1 kg of base resin (Ah + Ac) is 0.5 mol or more, and that the ratio of the amount of blended Ah to the total (Ah + Ac) [Ah / (Ah + Ac)] is greater than 0.5. By having the total amount (Ah + Ac) and the ratio [Ah / (Ah + Ac)] within the above range, the long-term thermal insulation properties of the resulting extruded foam board can be improved.

[0096] From the viewpoint of further improving the thermal insulation properties of the extruded foam board, the total amount (Ah + Ac) is preferably 0.6 mol or more, and more preferably 0.7 mol or more, per 1 kg of base resin.

[0097] On the other hand, from the viewpoint of more reliably suppressing the occurrence of numerous gas spots and the deterioration of the appearance of the extruded foam board, and more reliably suppressing the deterioration of the heat resistance of the extruded foam board, the total amount (Ah + Ac) is preferably 1.3 mol or less, more preferably 1.1 mol or less, and even more preferably 1.0 mol or less per 1 kg of base resin.

[0098] From the viewpoint of improving the long-term thermal insulation and flame retardancy of the extruded foam board, the ratio [Ah / (Ah+Ac)] is preferably 0.55 or higher, more preferably 0.65 or higher, and even more preferably 0.75 or higher. The upper limit of the ratio [Ah / (Ah+Ac)] is 1.0.

[0099] From the viewpoint of suppressing gas spots and improving the appearance of the extruded foam board, it is preferable to use water and / or alcohol (i.e., one or both of water and alcohol) among the other physical blowing agents mentioned above, and it is even more preferable to use both water and alcohol.

[0100] When using both water and alcohol, there are no restrictions on the ratio of the two, but water:alcohol = 90mol%:10mol% to 50mol%:50mol% is preferred, and 80mol%:20mol% to 60mol%:40mol% is more preferred.

[0101] As the alcohol, aliphatic alcohols having 1 to 5 carbon atoms are preferred. Examples include methyl alcohol (methanol), ethyl alcohol (ethanol), n-propyl alcohol, isopropyl alcohol, butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, aryl alcohol, clotyl alcohol, propagyl alcohol, n-amyl alcohol, sec-amyl alcohol, isoamyl alcohol, tert-amyl alcohol, neopentyl alcohol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-2-butanol, etc., which can be used alone or in combination of two or more. From the viewpoint of improving the appearance of the extruded foam board, ethanol can be preferably used among these.

[0102] The ratio of the amount of water and / or alcohol per 1 kg of base resin to the amount of HFO per 1 kg of base resin [(amount of water and / or alcohol) / amount of HFO] is, for example, 0.3 to 2.5. From the viewpoint of improving the surface condition of the extruded foam board, [(amount of water and / or alcohol) / amount of HFO] is preferably 0.4 to 2, more preferably 0.5 to 1.5, and even more preferably 0.6 to 1.2. The amount of water and / or alcohol per 1 kg of base resin is preferably 0.2 mol or more, more preferably 0.3 mol or more, and even more preferably 0.4 mol or more. The upper limit of the amount of water and / or alcohol per 1 kg of base resin is, for example, 0.8 mol.

[0103] From the viewpoint of more reliably suppressing gas spots and improving the appearance of the extruded foam board, the amount of water and / or alcohol blended is preferably 0.2 mol or more, more preferably 0.3 mol or more, even more preferably 0.4 mol or more, and particularly preferably 0.5 mol or more, per 1 kg of base resin. The upper limit of the amount of water and / or alcohol blended is, for example, 0.8 mol per 1 kg of base resin. The amount of water blended is, for example, 0.1 mol or more and 0.6 mol or less, preferably 0.3 mol or more and 0.5 mol or less, per 1 kg of base resin. Preferably 0.05 mol or more and 0.3 mol or less, and more preferably 0.1 mol or more and 0.2 mol or less.

[0104] Furthermore, the total amount of physical blowing agent is preferably, for example, 0.8 mol or more and 1.8 mol or less per 1 kg of base resin. From the viewpoint of more easily obtaining an extruded foam board with the desired apparent density, the total amount of physical blowing agent is preferably 1.0 mol or more per 1 kg of base resin. On the other hand, from the viewpoint of further suppressing the separation of the blowing agent from the extruded foam board and the generation of gas spots, the total amount of physical blowing agent is preferably 1.6 mol or less per 1 kg of base resin.

[0105] [Radiation suppressant] In the manufacturing method of the present invention, various additives such as the aforementioned radiation suppressants, flame retardants, flame retardant aids, and heat stabilizers can be used.

[0106] Furthermore, in the manufacturing method of the present invention, other known additives may be appropriately blended into the base resin as needed. Examples of other additives include foam regulators, colorants such as pigments and dyes, heat stabilizers, fillers, and various other additives.

[0107] In the manufacturing method of the present invention, a method can be employed in which a predetermined proportion of the flame retardant and other additives are supplied together with the base resin to a supply unit located upstream of the extruder and kneaded in the extruder. Alternatively, a method can be employed in which the flame retardant and other additives are supplied into the molten resin from a supply unit located in the middle of the extruder.

[0108] Specifically, methods such as supplying a dry blend of flame retardants, other additives, and a base resin to an extruder for melt-kneading, supplying a melt-kneaded mixture of flame retardants, other additives, and a base resin kneaded in a kneader to an extruder, and preparing a masterbatch in which a high concentration of flame retardants and other additives are pre-mixed with a base resin, supplying this to an extruder for melt-kneading with the base resin can be employed. Particularly from the viewpoint of dispersibility, it is preferable to prepare a flame retardant masterbatch and supply it to the extruder. For the preparation of the flame retardant masterbatch, it is preferable to use a base resin with a melt flow rate of about 0.5 to 30 g / 10 min at 200°C and a load of 5 kg, and to adjust the masterbatch so that it contains 10 to 95% by mass of flame retardant, more preferably 30 to 90% by mass, and even more preferably 50 to 85% by mass. [Examples]

[0109] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the contents of the examples.

[0110] In the examples and comparative examples, the following extrusion apparatus and raw materials were used for production.

[0111] [Extruder] An extrusion apparatus was used in which a first extruder with an inner diameter of 180 mm and a second extruder with an inner diameter of 225 mm were connected in series, an injection port for a physical foaming agent was provided near the end of the first extruder, and a flat die equipped with a resin discharge port (die lip) with a rectangular cross-section and a gap of 2.5 mm x width of 400 mm was connected to the outlet of the second extruder. A shaping device (guider) consisting of a pair of upper and lower polytetrafluoroethylene resin plates was attached to the resin outlet of the flat die so that the upper and lower resin plates were parallel to each other.

[0112] <1> Base resin Table 1 shows the details of the base resins used. The melt viscosity of the thermoplastic resins in Table 1 was measured using a Capillograph 1D manufactured by Toyo Seiki Seisakusho Co., Ltd., by the following method: A capillary with a hole diameter of 1.0 mm and a length of 10.0 mm was attached to the tip of a cylinder with a cylinder diameter of 9.55 mm and a length of 350 mm. After heating the cylinder and capillary to 200°C, the sample to be measured (resin pellets) was filled into the cylinder and preheated for 4 minutes to melt it completely. The melt viscosity of the resin was measured under conditions of a shear rate of 100 sec⁻¹.

[0113] [Table 1]

[0114] <2> Flame retardant Brominated styrene-butadiene copolymer (manufactured by Lanxess K.K.: "Emerald Innovation 3000") Brominated bisphenol (manufactured by Suzuhiro Chemical Co., Ltd.: FCP-680, tetrabromobisphenol A-bis(2,3-dibromopropyl ether))

[0115] <3> Bubble regulator Talc (manufactured by Matsumura Sangyo Co., Ltd.: High Filler #12, particle size (d50) 7.5 μm)

[0116] <4> Radiation suppressant Graphite (manufactured by Nippon Graphite Industries Co., Ltd.: CP-N (flaky graphite), primary particle size (d50) = 13.5 μm, fixed carbon content 99%)

[0117] <5> Physical foaming agent • Hydrofluoroolefin (HFO) 1-Chloro-3,3,3-trifluoropropene (HFO-1224yd): Manufactured by AGC Corporation 1-Chloro-3,3,3-trifluoropropene (HFO-1233zd): Manufactured by Honeywell Trans-1,3,3,3-tetrafluoropropene (HFO-1234ze): Manufactured by Honeywell cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz): Manufactured by Mitsui Chemours Fluoroproducts Ltd. Isobutane (i-Bu) ·water Ethanol (EtOH) • Dimethyl ether (DME)

[0118] The base resin, flame retardant, and foam regulator shown in Table 2 were supplied to the first extruder, heated to 200°C and kneaded, and the physical foaming agent shown in Table 2 was supplied from the physical foaming agent inlet provided in the first extruder and kneaded further to form a foamed resin molten material. Next, the obtained foamed resin molten material was transferred to the second extruder to adjust the resin temperature, and then extruded into a guider at a discharge rate of 700 kg / hr, passing through the guider while foaming to form a plate (shaping) to obtain a base plate of extruded foam board with a thickness of 55 mm. After that, the molded skin on both sides of the base plate was evenly cut to obtain a plate-shaped extruded foam board (width: 910 mm, length: 2000 mm, thickness: 50 mm, area of ​​the cross-section perpendicular to the extrusion direction: 455 cm²). 2 ) was manufactured. The extruded foam board after manufacturing was left to stand for 24 hours at a temperature of 23°C and 50% RH, and the following <1> ~ <10> This was used for evaluation.

[0119] [Table 2]

[0120] Regarding the obtained extruded foam board, the following applies: <1> ~ <10> The following items were evaluated. Table 2 shows <1> ~ <10> The evaluation results for the following items are shown.

[0121] <1> Apparent density Apparent density was measured in accordance with JIS K6767 (1999). Rectangular samples measuring 50 mm (length) x 50 mm (width) x 50 mm (thickness) were cut from three locations: the center and near both ends of each extruded foam board in the width direction. The apparent density of each sample was measured, and the arithmetic mean of the three measurements was taken as the apparent density.

[0122] <2> Closed cell ratio The closed-cell ratio of the extruded foam board was determined using the following equation (3), similar to the one described above, with the true volume Vx of the extruded foam board measured using an air-comparative hydrometer (Toshiba Beckmann Corporation, air-comparative hydrometer, model: 930), according to procedure C of ASTM-D2856-70. The average value for N=3 was used as the closed-cell ratio.

[0123] S(%)=(Vx-W / ρ)×100 / (V A -W / ρ)···(3) Vx: True volume (cm³) of the cut sample measured by the method described above. 3 (This corresponds to the sum of the volume of resin constituting the cut sample of the extruded foam board and the total volume of the closed-cell portions within the cut sample.) V A : The apparent volume (cm³) of the cut sample calculated from the external dimensions of the cut sample used for measurement. 3 ) W: Total mass (g) of the cut sample used for measurement ρ: Density of the resin constituting the extruded foam board (g / cm³) 3 )

[0124] <3> Average bubble diameter in the thickness direction The average bubble diameter in the thickness direction was determined by the following method: Magnified photographs were taken at three locations in the vertical cross-section of the obtained extruded foam board, specifically near the center and both ends, with the magnification adjusted to 100x. The maximum diameter of individual bubbles in the thickness direction was measured in each photograph using the image processing software NS2K-pro manufactured by Nano System Co., Ltd., and the average bubble diameter in the thickness direction was determined by arithmetic mean of these values.

[0125] <4> Bubble deformation rate The bubble deformation rate was determined by measuring the maximum diameter in the width direction of each individual bubble using the image processing software NS2K-pro from NanoSystems Inc. on magnified photographs of the bubbles, and then calculating the average bubble diameter in the width direction by taking the arithmetic mean of these values. Finally, the average bubble diameter in the thickness direction was divided by the average bubble diameter in the width direction.

[0126] <5> Content of physical blowing agents (HFO, isobutane) (Ch, Cc) The HFO content (Ch) and isobutane content (Cc) per 1 kg of extruded foam board were determined. The Ch and Cc content were determined by gas chromatography as described below.

[0127] Specifically, a test specimen measuring 500 mm in length, 200 mm in width, and 5 mm in thickness, without a molded surface, was cut from the center of the extruded foam board. This specimen was conditioned by standing in an atmosphere of 23°C and 50% humidity for 37 days (i.e., Method (1)). Five samples weighing approximately 1 g each were cut from this specimen. Five points were selected along the length of the specimen, near the center in the width direction, at 20 mm intervals. From each point, a 1 g sample with its original thickness (i.e., 5 mm) was cut. Gas chromatography analysis was performed to measure the content of HFO and aliphatic saturated hydrocarbons in the extruded foam board. The measured content was converted to the unit content of HFO and isobutane per 1 kg of extruded foam board (mol / kg). The arithmetic mean values ​​(mol / kg) of HFO and isobutane content per 1 kg of extruded foam board obtained from five samples were defined as the HFO content Ch (mol / kg) and the isobutane content Cc (mol / kg) per 1 kg of extruded foam board.

[0128] Gas chromatographic analysis was performed as follows: The above samples were accurately weighed and placed in a sealed sample bottle containing 50 mL of toluene solution (containing approximately 0.02 g of accurately weighed cyclopentane as an internal standard). The bottle was immediately sealed, and the mixture was thoroughly stirred to dissolve the physical foaming agent in the sample into the toluene, which was then used as the measurement sample. Approximately 2 μL of this solution was taken using a microsyringe and injected into a gas chromatograph to obtain a chromatogram.

[0129] The measurement conditions for the gas chromatograph are as follows: Equipment used: GC-14B manufactured by Shimadzu Corporation Column: Glass column for Shimadzu GC-14B, manufactured by Shinwa Chemical Co., Ltd. • Packed column: Glass column, 4.1m length x 3.2mm inner diameter ·Stationary phase: Silicone DC550 20% • Carrier: Chromosorb W AW DMCS (60 / 80 mesh) Column temperature: 40℃ Detector: FID Carrier gas: Nitrogen Carrier gas flow rate: 50 mL / min Inlet temperature: 200℃ Detector temperature: 200℃ From the obtained gas chromatograms, the peak areas of each physical blowing agent component were read, and the HFO content and isobutane content were calculated using an internal standard and a calibration curve of the relative sensitivity of each blowing agent component.

[0130] The residual HFO percentage Rh was calculated from the HFO content Ch per 1 kg of extruded foam board using the following formula (4). Specifically, the residual HFO percentage Rh was calculated by dividing the HFO content Ch per 1 kg of extruded foam board by the amount of HFO added per 1 kg of extruded foam board Bh during the manufacturing of the extruded foam board, and multiplying by 100 to convert it to a percentage. Similarly, the residual isobutane percentage Rc was calculated from the aliphatic saturated hydrocarbon content Cc per 1 kg of extruded foam board using the following formula (5). Rh = Ch / Bh × 100 ... (4) Rc = Cc / Bc × 100 ... (5)

[0131] <6> Thermal insulation Thermal insulation performance was evaluated by measuring the thermal conductivity of the extruded foam board. The thermal conductivity of the extruded foam board was measured in accordance with the accelerated test described in ISO 11561, except for changing the thickness of the test specimen. This standard determines the long-term change in thermal conductivity due to the release of foaming agent from the extruded foam board by accelerated testing. Specifically, it is as follows: A test specimen measuring 500 mm in length, 200 mm in width, and 5 mm in thickness, without the molded surface, is cut from the center of the extruded foam board, and the specimen is conditioned by being left undisturbed for 37 days in an atmosphere of 23°C and 50% humidity. The thermal conductivity of this specimen is measured based on the flat plate heat flow meter method (two heat flow meters, high temperature side 38°C, low temperature side 8°C, average temperature 23°C) described in JIS A1412-2:1999.

[0132] Based on the measured thermal conductivity, the thermal insulation performance was evaluated according to the following criteria. A: 0.026W / m·K or less B: Over 0.026 W / m and less than 0.027 W / m·K C: 0.027W / m·K or more

[0133] <7> exterior The appearance was evaluated by visually observing gas spots (excessively large bubbles with a diameter of 2 mm or more, observed on the surface and cross-section due to the separation of the foaming agent during extrusion foaming) in the obtained raw material. The criteria for evaluating the appearance are as follows: ◎: Almost no gas spots are visible on the surface of the original plate or on the cross-section perpendicular to the extrusion direction. ○: Slight gas spots are visible on the surface of the original plate and on the cross-section perpendicular to the extrusion direction. ×: Numerous gas spots are visible on the surface of the original plate and on the cross-section perpendicular to the extrusion direction.

[0134] <8> heat resistance The heat resistance was evaluated by measuring the dimensional change rate after heating extruded foam boards at multiple temperatures (55, 60, 65, 70, 75, 80°C) for 22 hours. Specifically, the dimensional change rate was measured as follows:

[0135] First, the extruded foam board was left to stand for 12 hours at 23°C. After standing, a test specimen without a skin surface was cut from the extruded foam board with dimensions of 25 mm in the thickness direction, 100 mm in the extrusion direction, and 100 mm in the width direction. The dimension Db in each direction (VD, MD, TD) of the cut test specimen was measured. VD is the thickness direction, MD is the extrusion direction, and TD is the width direction. Then, the test specimen was placed in an oven adjusted to 55°C, and after 22 hours, the test specimen was removed and the dimension Da in each direction (VD, MD, TD) was measured. For the dimension Da of the heated test specimen, the dimensional change rate in each direction relative to the dimension Db of the test specimen before heating was calculated using the formula [(Da-Db) / Db×100]. Of the obtained dimensional change rates in each direction, the largest value was taken as the dimensional change rate at 55°C. This method was repeated at temperatures of 60°C, 65°C, 70°C, 75°C, and 80°C, and the dimensional change rate at each temperature was determined. The "Heat Resistance" column in the table shows the maximum temperature at which the dimensional change rate was within ±1%.

[0136] <9> Flame retardant (Oxygen index) Flame retardancy was evaluated by the oxygen index. Specifically, the oxygen index was measured in accordance with the combustion test method for polymer materials using the oxygen index method described in JIS K7201-2 (2007). Multiple test pieces measuring 10 mm wide x 150 mm long x 10 mm thick were cut from the center of the width direction of the extruded foam board and used after being conditioned at a temperature of 23 degrees Celsius and a relative humidity of 50% for 168 hours. A flame retardancy tester (ON-1D model, manufactured by Suga Test Instruments Co., Ltd.) was used as the measuring instrument. The heat source for the igniter was liquefied petroleum gas (LPG), and the ignition procedure was method A, with the test piece standing upright in a designated position inside the tester. Flame retardancy was evaluated according to the following criteria based on the measured oxygen index, and is shown in the "Flame Retardancy" column of the table. ○: Oxygen index exceeds 28 ×: Oxygen index below 28

[0137] (Flammability test) Furthermore, for the cases where the oxygen index evaluation above was "○", the following flammability test was conducted to confirm that it passed. Specifically, extruded foam boards 7 days after manufacture were subjected to a flammability test in accordance with measurement method A of the flammability test method of JIS A9521:2017. For the measurement, five test pieces were randomly cut from one extruded foam board, and those that met the following criteria were considered to have passed. Passing criteria: The average flame extinction time for the five test specimens is within 3 seconds, there is no residue, and the material does not burn beyond the flammability limit. In all cases where the oxygen index evaluation above was "○", the above flammability test was also passed.

[0138] <10> Compressive strength For Examples 1, 2, Comparative Example 1, 2, 3, and 4, the compressive strength of the obtained extruded foam boards was measured. Specifically, in accordance with JIS K7181 (2011), the following method was used with a Tensilon universal material testing machine manufactured by A&D Co., Ltd. A test piece (50 mm in the extrusion direction × 50 mm in the width direction × 25 mm in thickness [excluding the skin layer]) cut from the center of the extruded foam board was compressed by 10% at a speed of 10 mm / min to obtain a stress-strain curve. The stress at 10% compression was read from the obtained stress-strain curve and the 10% compressive strength was determined by dividing it by the compressed area of ​​the test piece. The above measurement was performed in the three directions of the extrusion direction, width direction, and thickness direction of the extruded foam board, and the arithmetic mean was taken as the compressive strength.

[0139] The compressive strength of the extruded foam board was 30.6 N / cm² in Example 1. 2 Example 2 showed a pressure of 25.5 N / cm². 2 Comparative Example 1 had a pressure of 24.5 N / cm². 2 Comparative Example 2 had a pressure of 25.4 N / cm². 2 Comparative Example 3 had a pressure of 23.9 N / cm². 2 Comparative Example 4 had a pressure of 22.4 N / cm². 2 That was the case.

[0140] As can be seen from Table 2, Examples 1 to 9 use a styrene-acrylonitrile copolymer as the base resin, and the total amount (Ch+Cc) of hydrofluoroolefin (Ch) and the amount of one or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms (Cc) is between 0.5 mol and 1.3 mol, and the ratio of Ch to the total amount (Ch+Cc) [Ch / (Ch+Cc)] is greater than 0.5. In Examples 1 to 9, it was confirmed that they exhibited high flame retardancy and excellent long-term heat insulation. Examples 1 to 6, which contained 1-chloro-2,3,3,3-tetrafluoropropene as the hydrofluoroolefin, also showed excellent heat resistance. In Comparative Examples 1 to 7, where at least one of the total amount (Ch+Cc) and [Ch / (Ch+Cc)] did not meet the numerical range of the present invention, it was not possible to achieve good heat insulation and flame retardancy.

Claims

1. A base resin containing a styrene-acrylonitrile copolymer and a flame retardant, with an apparent density of 20 kg / m³. ３ More than 50kg / m ３ Below, the cross-sectional area perpendicular to the extrusion direction is 100 cm². ２ The above, and a thermoplastic resin extruded foam board with a thickness of 20 mm or more and 150 mm or less, The total amount (Ch + Cc) of hydrofluoroolefin content Ch and C3-C5 aliphatic saturated hydrocarbon content Cc (including 0) per 1 kg of thermoplastic resin extruded foam board, measured by gas chromatography using a test specimen conditioned by the method (1) below, is 0.5 mol or more and 1.3 mol or less, and the ratio of the Ch content to the total amount (Ch + Cc) [Ch / (Ch + Cc)] is greater than 0.

5. The hydrofluoroolefin comprises one or more selected from the group consisting of 1-chloro-2,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene, and 1,1,1,4,4,4-hexafluoro-2-butene. Thermoplastic extruded foam board. Method (1): A test piece measuring 500 mm in length, 200 mm in width, and 5 mm in thickness, without a molded surface, is cut from a thermoplastic resin extruded foam board. The test piece is then conditioned by standing in an atmosphere of 23°C and 50% humidity for 37 days.

2. The molecular weight of the hydrofluoroolefin is 110 or more. The thermoplastic resin extruded foam board according to claim 1.

3. The hydrofluoroolefin is 1-chloro-2,3,3,3-tetrafluoropropene. The thermoplastic resin extruded foam board according to claim 1.

4. The content of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms (Cc) per 1 kg of the thermoplastic resin extruded foam board is 0.1 mol or more and 0.6 mol or less. The thermoplastic resin extruded foam board according to claim 1.

5. The average bubble diameter in the thickness direction of the thermoplastic resin extruded foam board is 50 μm or more and 300 μm or less. The thermoplastic resin extruded foam board according to claim 1.

6. The content of the acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base resin is 20% by mass or more and 40% by mass or less. The thermoplastic resin extruded foam board according to claim 1.

7. The flame retardant contains a brominated styrene-butadiene copolymer, and the amount of the brominated styrene-butadiene copolymer is 0.5 parts by mass or more and 8 parts by mass or less per 100 parts by weight of the base resin. The thermoplastic resin extruded foam board according to claim 1.

8. The flame retardant further contains brominated bisphenol, wherein the amount of brominated bisphenol is 0.1 parts by mass or more and 1 part by mass or less per 100 parts by mass of the base resin, and the ratio of the amount of brominated bisphenol to the amount of brominated styrene-butadiene copolymer is 0.05 or more and 0.3 or less. The thermoplastic resin extruded foam board according to claim 7.

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