Method for manufacturing extruded thermoplastic foam boards

Abstract

To provide a method for manufacturing a thermoplastic resin extrusion foam plate which has a good heat insulation property, flame retardancy, heat resistance and appearance.SOLUTION: A method for manufacturing a thermoplastic resin extrusion foam plate includes a step of extrusion foaming a foamable molten resin composition containing a base material resin containing a styrene-acrylonitrile copolymer, a flame retardant and a physical foaming agent, and molding the foamable molten resin composition into a plate shape by a molding tool, in which apparent density is 20 kg / m3 or more and 50 kg / m3 or less, and an extrusion direction vertical cross-sectional area is 100 cm2 or more, wherein a content of the acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base material resin is 10 mass% or more and 40 mass% or less, the physical foaming agent contains 1-chloro-2,3,3,3-tetrafluoropropene, and a blending amount Ah of the 1-chloro-2,3,3,3-tetrafluoropropene to 1 kg of the base material resin is 0.4 mol or more and 1.3 mol or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing thermoplastic resin extruded foam boards, and more specifically, to a method for manufacturing thermoplastic resin extruded foam boards that can be suitably used as thermal 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 in an extruder, then injecting a physical foaming 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 thermal insulation properties. One method for manufacturing extruded foam boards with excellent thermal insulation properties 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] For example, Patent Documents 1 to 4 disclose a technology for manufacturing extruded foam boards using polystyrene resin as the base resin and HFO as the physical foaming agent. In these patent documents, HFOs such as 1-chloro-3,3,3-trifluoropropene (HFO-1233zd), 1,3,3,3-tetrafluoropropene (HFO-1234ze), and 1-chloro-3,3,3-trifluoropropene (HFO-1224yd) are used. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-82147 [Patent Document 2] International Publication No. WO2017 / 141888 [Patent Document 3] Special Publication No. 2010-522808 [Patent Document 4] Japanese Patent Publication No. 2022-111660 [Overview of the project] [Problems that the invention aims to solve]

[0006] To improve the thermal insulation properties of extruded foam boards, it is necessary to retain a sufficient amount of HFO in the resulting extruded foam board. However, in the technologies described in Patent Documents 1 to 4, HFO does not easily remain in the polystyrene resin, leaving room for improvement from the viewpoint of further enhancing thermal insulation properties. Furthermore, when the amount of HFO added was increased in an attempt to improve the thermal insulation properties of the extruded foam board, the heat resistance of the resulting extruded foam board was sometimes impaired. Taking these circumstances into consideration, the present invention provides a method for manufacturing a thermoplastic resin extruded foam board that has good thermal insulation properties, flame retardancy, heat resistance, and appearance. [Means for solving the problem]

[0007] According to the present invention, a method for manufacturing a thermoplastic resin extruded foam board is provided as shown below.

[0008] [1] A foamed molten resin composition comprising a base resin containing a styrene-acrylonitrile copolymer, a flame retardant, and a physical blowing agent, which is extruded and foamed and then molded into a sheet using a molding tool, 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. 2A method for manufacturing the above thermoplastic resin extruded foam board, wherein the content of the acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base resin is 10% by mass or more and 40% by mass or less, the physical foaming agent contains 1-chloro-2,3,3,3-tetrafluoropropene, and the blending amount Ah of the 1-chloro-2,3,3,3-tetrafluoropropene with respect to 1 kg of the base resin is 0.4 mol or more and 1.3 mol or less.

[0009] [2] In the method for manufacturing the thermoplastic resin extruded foam board according to [1], the content of the acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base resin is 20% by mass or more.

[0010] [3] In the method for manufacturing the thermoplastic resin extruded foam board according to [1] or [2], 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.

[0011] [4] In the method for manufacturing the thermoplastic resin extruded foam board according to [3], the flame retardant further contains a brominated bisphenol, the blending amount of the brominated bisphenol is 0.1 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the base resin, and the ratio of the blending amount of the brominated bisphenol to the blending amount of the brominated styrene-butadiene copolymer is 0.05 or more and 0.3 or less.

[0012] [5] In the method for manufacturing the thermoplastic resin extruded foam board according to any one of [1] to [4], the physical foaming agent further contains an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, and the sum (Ah + Ac) of the blending amount Ah of the 1-chloro-2,3,3,3-tetrafluoropropene with respect to 1 kg of the base resin and the blending amount Ac of the hydrocarbon with respect to 1 kg of the base resin is 0.5 mol or more, and the ratio [Ah / (Ah + Ac)] of the blending amount Ah to the sum (Ah + Ac) is more than 0.5.

[0013] [6] In the method for producing a thermoplastic resin extrusion foam board according to any one of [1] to [5] above, further comprising water and / or alcohol, and the ratio of the blending amount of the water and / or alcohol to the blending amount Ah of the 1-chloro-2,3,3,3-tetrafluoropropene is 0.4 or more and 2 or less.

Effect of the Invention

[0014] According to the production method of the present invention, it is possible to produce a thermoplastic resin extrusion foam having good heat insulation, flame retardancy, heat resistance and appearance.

Embodiments for Carrying out the Invention

[0015] <Method for Producing Thermoplastic Resin Extrusion Foam Board> Hereinafter, the method for producing a thermoplastic resin extrusion foam board of the present invention will be described in detail. The method for producing a thermoplastic resin extrusion foam board (hereinafter, also simply referred to as "extrusion foam board") according to the present invention includes a step of extruding and foaming a foamable molten resin composition containing a base resin, a flame retardant and a physical foaming agent and forming it into a plate shape by a molding tool, and the apparent density is 20 kg / m 3 or more and 50 kg / m 3 or less, and it is a method for producing a thermoplastic resin extrusion foam board with a cross-sectional area perpendicular to the extrusion direction of 100 cm 2 or more.

[0016] Generally speaking, the production method of the present invention is, for example, adding additives such as a flame retardant and a bubble regulator to a base resin, supplying it to an extruder, heating it, melting and kneading it. Next, a physical foaming agent is pressed into the extruder and further kneaded to obtain a foamable molten resin composition, and the foamable molten resin composition is extruded from a high-pressure region to a low-pressure region (usually in the atmosphere) to be foamed. Then, the obtained foam is shaped into a plate shape using a shaping device (such as a guide) connected to the die outlet of the extruder, thereby producing a thermoplastic resin extrusion foam board. As the shaping device, for example, a device composed of a pair of upper and lower polytetrafluoroethylene plates is used.

[0017] [Base Resin] The manufacturing method according to the present invention uses a base resin containing a styrene-acrylonitrile copolymer. 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.

[0018] By using a styrene-acrylonitrile copolymer as the base resin, it becomes easy to obtain extruded foam boards with excellent heat insulation and heat resistance.

[0019] Styrene-acrylonitrile copolymers are copolymers of styrene and acrylonitrile. A single styrene-acrylonitrile copolymer may be used, or a mixture of two or more copolymers with different copolymerization ratios of styrene and acrylonitrile may be used.

[0020] The content of acrylonitrile components derived from styrene-acrylonitrile copolymer in the base resin is 10% by mass or more and 40% by mass or less.

[0021] If the acrylonitrile component content in the base resin is too low, 1-chloro-2,3,3,3-tetrafluoropropene, as described later, may not remain in the extruded foam board. Furthermore, if 1-chloro-2,3,3,3-tetrafluoropropene is blended in a relatively large amount within the blending range described later as a physical blowing agent, the heat resistance of the resulting extruded foam board may be significantly reduced. Considering the above circumstances, the acrylonitrile component content derived from the styrene-acrylonitrile copolymer in the base resin is preferably 15% by mass or more, and more preferably 20% by mass or more.

[0022] On the other hand, if the acrylonitrile component content in the base resin is too high, gas spots may occur frequently on the surface of the extruded foam board, making it impossible to obtain a good quality extruded foam board. Considering these circumstances, the acrylonitrile component content derived from the styrene-acrylonitrile copolymer in the base resin is preferably 35% by mass or less, and more preferably 30% by mass or less.

[0023] 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.

[0024] The acrylonitrile content in styrene-acrylonitrile copolymer can be determined by pyrolysis gas chromatography analysis.

[0025] 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.

[0026] The melt viscosity of the base resin used in the manufacturing method of the present invention is preferably 500 to 4000 Pa·s, more preferably 1000 to 3700 Pa·s, and even more preferably 1200 to 3000 Pa·s, due to its excellent foaming 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.

[0027] [Physical foaming agent] The physical foaming agent used in the present invention contains 1-chloro-2,3,3,3-tetrafluoropropene (hereinafter also referred to as "HFO-1224yd").

[0028] When manufacturing extruded foam boards using styrene-acrylonitrile copolymer as the base resin, adding a predetermined amount of HFO-1224yd as a physical blowing agent results in an effect that, compared to other hydrofluoroolefins (e.g., 1,3,3,3-tetrafluoropropene, 1,1,1,4,4,4-hexafluoro-2-butene, 1-chloro-3,3,3-trifluoropropene), does not impair the heat resistance or appearance of the resulting extruded foam board, and HFO-1224yd tends to remain in the extruded foam board. The reason for this is not clear, but it is thought that HFO-1224yd has significantly better solubility and foaming properties in styrene-acrylonitrile copolymers compared to other HFOs.

[0029] Here, the statement that HFO-1224yd tends to remain in extruded foam boards means, for example, that the proportion of HFO-1224yd per 1 kg of extruded foam board (i.e., the HFO-1224yd retention rate) is high, measured by gas chromatography using test specimens conditioned by method (1) described later, relative to the amount of HFO-1224yd blended per 1 kg of extruded foam board during manufacturing. A high HFO-1224yd retention rate makes it easier to obtain extruded foam boards with excellent long-term thermal insulation properties.

[0030] Furthermore, because HFO-1224yd is non-flammable, it reduces the risk of ignition due to static electricity during the manufacturing of extruded foam boards. In addition, HFO-1224yd has a low ozone depletion potential and a very low global warming potential, thus having a small impact on the environment.

[0031] The amount Ah of HFO-1224yd added per 1 kg of base resin is between 0.4 mol and 1.3 mol.

[0032] From the viewpoint of improving the long-term thermal insulation properties of the 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, particularly preferably 0.7 mol or more, and most preferably 0.8 mol or more.

[0033] 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 1.2 mol or less, more preferably 1.1 mol or less, even more preferably 1.0 mol or less, and particularly preferably 0.9 mol or less.

[0034] As described above, the manufacturing method of the present invention uses the specific resin as the base resin, and the content of the acrylonitrile component in the base resin is adjusted to a predetermined range. Therefore, even when a large amount of 1-chloro-2,3,3,3-tetrafluoropropene is blended as a physical blowing agent, for example, 0.5 mol or more per 1 kg of base resin, the heat resistance and appearance of the extruded foam board are not impaired. Furthermore, the residual amount of 1-chloro-2,3,3,3-tetrafluoropropene in the extruded foam board is maintained at a high level over a long period of time. Therefore, an extruded foam board with excellent heat insulation properties can be stably obtained.

[0035] The proportion of HFO-1224yd 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-1224yd 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%.

[0036] The physical blowing agent may include other physical blowing agents besides HFO-1224yd, 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), carbon dioxide, and hydrofluoroolefins other than HFO-1224yd.

[0038] From the viewpoint of increasing the compressive strength of the resulting extruded foam board, 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.

[0039] 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 or more and 0.6 mol or less, more preferably 0.2 mol or more and 0.5 mol or less, and more preferably 0.3 mol or more and 0.45 mol or less. By setting the amount of Ac within the above range, the compressive strength of the resulting extruded foam board can be further increased.

[0040] It is preferable that the sum of the amount Ah added to 1 kg of HFO-1224yd base resin and the amount Ac added to 1 kg of base resin containing aliphatic saturated hydrocarbons with 3 to 5 carbon atoms (Ah + Ac) is 0.5 mol or more, and that the ratio of the amount Ah added to the sum (Ah + Ac) [Ah / (Ah + Ac)] is greater than 0.5. By having the sum (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.

[0041] 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, more preferably 0.7 mol or more, and even more preferably 0.8 mol or more, per 1 kg of base resin.

[0042] 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.

[0043] 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, for example, 1.0.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] The ratio of the amount of water and / or alcohol per 1 kg of base resin (mol / kg) to the amount of HFO-1224yd per 1 kg of base resin (Ah) [(amount of water and / or alcohol) / Amount of HFO-1224yd Ah] is, for example, 0.3 to 2.5. From the viewpoint of improving the surface condition of the extruded foam board, it is preferable that [(amount of water and / or alcohol) / Amount of HFO-1224yd Ah] be 0.4 to 2, more preferably 0.5 to 1.5, and even more preferably 0.6 to 1.2.

[0048] 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 preferably 0.1 mol or more and 0.6 mol or less, more preferably 0.3 mol or more and 0.5 mol or less, per 1 kg of base resin. The amount of alcohol blended is preferably 0.05 mol or more and 0.3 mol or less, more preferably 0.1 mol or more and 0.2 mol or less, per 1 kg of base resin.

[0049] 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.

[0050] [Radiation suppressant] In the manufacturing method of the present invention, graphite can be added to the foamed molten resin composition as a radiation suppressor to improve thermal insulation. By adding graphite as a radiation suppressor, the effect of improving thermal insulation can be enhanced.

[0051] 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.

[0052] When graphite is incorporated, the amount of graphite added is, for example, 0.1 parts by mass or more and 5.0 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 exerted. 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 exerting 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.

[0053] Furthermore, in the manufacturing method of the present invention, in order to further improve the heat insulation properties, the extruded foam board may contain radiation suppressants other than graphite. 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 amount of radiation suppressant other than graphite added is preferably 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.

[0054] [Flame retardant] The extruded foam board obtained by the manufacturing method of the present invention is mainly used as an insulating material for building materials, and flame retardancy is imparted by blending a flame retardant into the base resin.

[0055] The amount of flame retardant added is preferably 0.1 parts by mass to 10 parts by mass per 100 parts by mass of base resin, more preferably 0.5 parts by mass to 8 parts by mass, and even more preferably 2 parts by mass to 7 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 added 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.

[0056] 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 brominated bisphenol compounds, such as (2,3-dibromopropyl ether), 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 can be used in combination. Among these, it is preferable to use a brominated styrene-butadiene copolymer. In particular, it is preferable that the main component of the flame retardant is a brominated styrene-butadiene copolymer. When the main component of the flame retardant is a brominated styrene-butadiene copolymer, the amount of 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 amount of brominated styrene-butadiene copolymer in the flame retardant is not particularly limited and may be 100% by mass.

[0057] From the viewpoint of improving flame retardancy, the amount of brominated styrene-butadiene copolymer blended is preferably 0.5 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the base resin, more preferably 1 part by mass or more and 6 parts by mass or less, and even more preferably 2 parts by mass or more and 5 parts by mass or less.

[0058] 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 manufacturing method 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 predetermined amount of 1-chloro-2,3,3,3-tetrafluoropropene is blended as a physical blowing agent.

[0059] Furthermore, from the viewpoint of more stably exhibiting flame retardancy when using brominated styrene-butadiene copolymer as a flame retardant, it is preferable to incorporate brominated bisphenol-based flame retardants 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.

[0060] 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 amount of brominated bisphenol to the amount of brominated styrene-butadiene copolymer is preferably 0.05 or more and 0.3 or less, and more preferably 0.1 or more and 0.25 or less.

[0061] 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.

[0062] [Flame retardant] Furthermore, in the manufacturing method of the present invention, a flame retardant additive can be used in combination with the flame retardant for the purpose of further improving the flame retardancy of the extruded foam board. 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 added 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.

[0063] 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.

[0064] [Bubble regulator] In the manufacturing method of the present invention, it is preferable to form a foamable molten resin composition by blending a foam regulator with a base resin. As the foam regulator, inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium dioxide, clay, aluminum oxide, bentonite, and diatomaceous earth can be used. Among these, talc is preferred because it is easy to adjust the bubble diameter and it is easy to reduce the bubble diameter without impairing flame retardancy. In particular, fine talc with a 50% particle size (light transmission centrifugal sedimentation method) of 0.1 μm to 20 μm is preferred, and fine talc with a particle size of 0.5 μm to 15 μm is preferred. The amount of foam regulator added varies depending on the type of regulator, the desired bubble diameter, etc., but when talc is used as the foam regulator, the amount of talc blended is preferably 0.1 parts by mass to 7 parts by mass per 100 parts by mass of base resin, more preferably 0.2 parts by mass to 5 parts by mass, and even more preferably 0.3 parts by mass to 3 parts by mass.

[0065] [Heat stabilizer] Heat stabilizers can improve the thermal stability of brominated flame retardants by being blended into raw materials or scraps when manufacturing extruded foam boards or when recycling and repelling scraps of extruded foam boards. Examples of such heat stabilizers include one or more heat stabilizers selected from 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). Preferably, the amount of heat stabilizer added is 0.1 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the total amount of flame retardant.

[0066] In the manufacturing method of the present invention, as a method of blending a flame retardant and other additives into a base resin, a method can be adopted in which a predetermined ratio of the flame retardant and other additives is supplied to a supply section provided upstream of an extruder together with the base resin and kneaded in the extruder. Alternatively, a method can also be adopted in which the flame retardant and other additives are supplied into the molten resin from a supply section provided in the middle of the extruder.

[0067] Specifically, a method can be adopted in which a dry blend of a flame retardant, other additives, and a base resin is supplied to an extruder and melt-kneaded, a method in which a melt-kneaded product obtained by kneading a flame retardant, other additives, and a base resin with a kneader or the like is supplied to an extruder, a method in which a masterbatch in which a high-concentration flame retardant and other additives are previously blended into a base resin is prepared and this is supplied to an extruder and melt-kneaded with the base resin, etc. In particular, from the viewpoint of dispersibility, it is preferable to adopt a method in which a flame retardant masterbatch is prepared and supplied to an extruder. The adjustment of the flame retardant masterbatch is preferably adjusted so that the base resin used has a melt flow rate of about 0.5 to 30 g / 10 minutes at 200°C and a load of 5 kg, and the flame retardant is contained in the masterbatch at 10 to 95% by mass, more preferably adjusted to be contained at 30 to 90% by mass, and still more preferably adjusted to be contained at 50 to 85% by mass.

[0068] <Thermoplastic resin extrusion foamed board> Hereinafter, an example of a thermoplastic resin extrusion foamed board obtained by the manufacturing method of the present invention will be described. However, the extrusion foamed board obtained by the manufacturing method of the present invention is not limited to the following examples. The thermoplastic resin extrusion foamed board according to an example of the present invention is a thermoplastic resin extrusion foamed board containing a base resin, a flame retardant, and a physical foaming agent. Details of the base resin, the flame retardant, and the physical foaming agent are as described above.

[0069] [Apparent density] The apparent density of the extrusion foamed board according to the present invention is, for example, 20 kg / m 3 or more and 50 kg / m 3 [[ID=二十]] 3 or less, preferably 20 kg / m 3 or more and 45 kg / m3 The following is more preferable: 25 kg / m 3 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 properties 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 (1), 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)···(1) 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 HFO-1224yd 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 suppressing radiant heat transfer and further improving thermal insulation, 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] Generally, in the manufacture of extruded foam boards, foaming and molding tend to become more difficult as the apparent density decreases and the cross-sectional area increases. However, the manufacturing method of the present invention offers excellent manufacturing stability, allowing for the stable production of extruded foam boards with good appearance, even when manufacturing boards with large thicknesses, widths, and cross-sectional areas. Extruded foam boards with good foaming properties and excellent surface smoothness can also be suitably used as extruded foam boards with a molded skin without cutting the surface in the thickness direction.

[0079] 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, for example, about 150 mm.

[0080] 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. Generally, when manufacturing wide extruded foam boards, shrinkage of the extruded foam board tends to occur more easily, possibly because the anisotropy of the air bubbles in the resulting extruded foam board tends to be higher. According to the manufacturing method of the present invention, since the manufacturing stability is excellent, even when manufacturing wide extruded foam boards, for example, with a width within the above range, they can be manufactured stably.

[0081] [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.

[0082] 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: 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. In this specification, this conditioning method is referred to as method (1). Then, the thermal conductivity is measured using the test specimen obtained by method (1) above, 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.

[0083] 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.

[0084] [Content of physical foaming agent] The following describes the content (residual amount) of the physical blowing agent (HFO-1224yd, one or more hydrocarbons selected from aliphatic saturated hydrocarbons with 3 to 5 carbon atoms) in extruded foam boards.

[0085] (1) HFO-1224yd The HFO-1224yd 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.

[0086] Furthermore, from the viewpoint of more reliably increasing the long-term thermal conductivity of the extruded foam board, the content Ch of HFO-1224yd 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-1224yd, it becomes possible to retain HFO-1224yd in the obtained extruded foam board at the high content described above.

[0087] 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-1224yd content Ch per 1 kg of extruded foam board is preferably 1.3 mol or less, more preferably 1.1 mol or less, and even more preferably 1.0 mol or less.

[0088] (2) Aliphatic saturated hydrocarbons with 3 to 5 carbon atoms When HFO-1224yd is used in combination with aliphatic saturated hydrocarbons having 3 to 5 carbon atoms as a physical blowing agent, the content Cc of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms 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 Cc of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms is within the above range, the compressive strength of the extruded foam board can be improved.

[0089] The total amount (Ch+Cc) of HFO-1224yd per 1 kg of extruded foam board, plus the amount of one or more hydrocarbons selected from aliphatic saturated hydrocarbons with 3 to 5 carbon atoms per 1 kg of extruded foam board, is between 0.5 mol and 1.3 mol, and the ratio of Ch content to the total amount (Ch+Cc) [Ch / (Ch+Cc)] is greater than 0.5. Having 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.

[0090] Furthermore, if aliphatic saturated hydrocarbons with 3 to 5 carbon atoms are not used in combination with HFO-1224yd (i.e., if the Cc content is 0), the total amount (Ch + Cc) corresponds to the Ch content, and the ratio [Ch / (Ch + Cc)] is 1.

[0091] From the viewpoint of suppressing the increase in thermal conductivity of extruded foam boards over long periods 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.

[0092] From the viewpoint of more reliably suppressing the risk of numerous gas spots forming in 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, and more preferably 1.0 mol or less, per kg of the extruded foam board.

[0093] From the viewpoint of more reliably suppressing the increase in thermal conductivity of extruded foam boards over long periods of time, 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.

[0094] In this specification, the content of the physical blowing agent (HFO-1224yd, aliphatic saturated hydrocarbon) in extruded foam board 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 (i.e., method (1)). A sample weighing 1 g is cut from the test piece, and the content of HFO-1224yd and aliphatic saturated hydrocarbon in the extruded foam board is measured by gas chromatography analysis. The content of the physical blowing agent obtained in a 37-day accelerated test with a test piece thickness of 5 mm corresponds, for example, to the content of the physical blowing agent in an extruded foam board with a thickness of 50 mm approximately 10 years after manufacture.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] According to the manufacturing method of 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 by blending 1-chloro-2,3,3,3-tetrafluoropropene as a physical blowing agent to produce an extruded foam board, the residual amount of 1-chloro-2,3,3,3-tetrafluoropropene 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 residual rate Rh of HFO-1224yd in the extruded foam board. The residual rate Rh of HFO-1224yd in the extruded foam board is expressed by the following formula (2). Rh = Ch / Bh × 100 ... (2)

[0099] Here, Bh is the amount of HFO-1224yd added per 1 kg of the extruded foam board (mol / kg) during the manufacturing of the extruded foam board, and Ch is the HFO-1224yd 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 residual rate Rh of HFO-1224yd in the extruded foam board is, for example, 65% or more, preferably 70% or more, and more preferably 75% or more. There is no particular upper limit to the residual rate Rh of HFO-1224yd in the extruded foam board, but it is generally around 90%.

[0100] Furthermore, if the physical blowing agent contains one or more hydrocarbons selected from aliphatic saturated hydrocarbons having 3 to 5 carbon atoms, the ratio (Rh / Rc) of the remaining rate Rh of HFO-1224yd 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 is preferably 0.8 or higher, more preferably 0.85 or higher, and even more preferably 0.9 or higher.

[0101] The remaining percentage 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 (3). Rc = Cc / Bc × 100 ... (3)

[0102] 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.

[0103] [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%.

[0104] 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. [Examples]

[0105] 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.

[0106] In the examples and comparative examples, the extrusion apparatus and raw materials described below were used.

[0107] [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.

[0108] <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.

[0109] [Table 1]

[0110] <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))

[0111] <3> Bubble regulator Talc (manufactured by Matsumura Sangyo Co., Ltd.: High Filler #12, particle size (d50) 7.5 μm)

[0112] <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%)

[0113] <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)

[0114] 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.

[0115] [Table 2]

[0116] 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.

[0117] <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.

[0118] <2> Closed cell ratio The closed-cell ratio of the extruded foam board was determined using the following formula (1), 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.

[0119] S(%)=(Vx-W / ρ)×100 / (V A -W / ρ)···(1) 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 )

[0120] <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.

[0121] <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.

[0122] <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.

[0123] Specifically, a test piece 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 test piece was conditioned by standing in an atmosphere of 23°C and 50% humidity for 37 days (Method (1)). Five samples weighing approximately 1 g each were cut from this test piece. Five points were selected along the length of the test piece, 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-1224yd and aliphatic saturated hydrocarbons in the extruded foam board. The measured content was converted to obtain the HFO and isobutane content (mol / kg) per 1 kg of extruded foam board. 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.

[0124] 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.

[0125] 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.

[0126] 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)

[0127] <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 was as follows: A test specimen measuring 500 mm in length, 200 mm in width, and 5 mm in thickness, without the molded surface, was cut from the center of the extruded foam board, and the specimen was conditioned by leaving it undisturbed for 37 days in an atmosphere of 23°C and 50% humidity (Method (1)). The thermal conductivity was measured using this specimen 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.

[0128] 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

[0129] <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.

[0130] <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:

[0131] 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%.

[0132] <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

[0133] (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 specimen does not burn beyond the flammability limit. In all cases where the oxygen index evaluation above was "○", the above flammability test was also passed.

[0134] <10> Compressive strength For Examples 1, 2, Comparative Example 1, 2, 4, and 5, 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.

[0135] 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 4 had a pressure of 23.9 N / cm². 2 Comparative Example 5 had a pressure of 22.4 N / cm². 2 That was the case.

[0136] As can be seen from Table 2, in Examples 1 to 6, in which a base resin whose main component is a styrene-acrylonitrile copolymer was blended with a predetermined amount of HFO-1224yd as a hydrofluoroolefin, the HFO retention was significantly better compared to Comparative Examples 1 to 13, and the long-term thermal insulation was excellent. Furthermore, in Examples 1 to 3, it was confirmed that sufficient heat resistance was maintained even when the amount of HFO-1224yd blended was increased, and the appearance was good in all cases. In addition, the obtained extruded foam boards had a high degree of flame retardancy. Details of Comparative Examples 1 to 13 are as follows.

[0137] Comparative Examples 1-3 are examples of extruded foam boards manufactured using polystyrene as the base resin and blending a predetermined amount of HFO-1224yd as a hydrofluoroolefin. The amount of HFO-1224yd blended differed among Comparative Examples 1-3. In Comparative Examples 1 and 2, it was confirmed that the HFO content (residual rate) decreased significantly over time, and the thermal insulation properties also decreased. Furthermore, in Comparative Example 3, where the amount of HFO-1224yd was increased, a good extruded foam board could not be obtained. In addition, in Comparative Examples 1-3, the heat resistance decreased when the amount of HFO-1224yd was increased.

[0138] Comparative Examples 4-6 are examples of extruded foam boards manufactured using a styrene-methyl methacrylate copolymer as the base resin and blending a predetermined amount of HFO-1224yd as a hydrofluoroolefin. The amount of HFO-1224yd blended differed among Comparative Examples 4-6. In Comparative Examples 4-6, it was confirmed that the HFO content (remaining rate) decreased significantly over time, resulting in a decrease in thermal insulation properties. Furthermore, it was confirmed that increasing the amount of HFO-1224yd also decreased heat resistance.

[0139] Comparative Example 7 uses a styrene-acrylonitrile copolymer as the base resin, but it is an example where the amount of HFO-1224yd added is too high. In Comparative Example 7, gas spots occurred frequently, foaming was difficult, and an extruded foam board could not be obtained.

[0140] Comparative Example 8 is an example in which an extruded foam board was manufactured using a styrene-acrylonitrile copolymer as the base resin and HFO-1233zd as the hydrofluoroolefin. In Comparative Example 8, it was confirmed that the heat resistance was significantly reduced.

[0141] Comparative Example 9 is an example in which an extruded foam board was manufactured using a styrene-acrylonitrile copolymer as the base resin and HFO-1234ze as the hydrofluoroolefin. In Comparative Example 9, the HFO content (remaining rate) decreased significantly over time. In addition, gas spots occurred frequently. Furthermore, there was room for improvement in flame retardancy.

[0142] Comparative Example 10 is an example where the acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base resin was too low. Over time, the HFO content (remaining rate) decreased, resulting in insufficient long-term thermal insulation.

[0143] Comparative Examples 11-13 are examples in which HFO-1336mzz was used in common, but the type of base resin was different. The main components of the base resins used in Comparative Examples 11-13 were polystyrene, styrene-methyl methacrylate copolymer, and styrene-acrylonitrile copolymer, respectively. HFO-1336mzz is a type of foaming agent that is known to be less likely to be released from foam boards and to have high persistence, and as can be seen from the results in Table 2, it tends to show a generally constant persistence rate regardless of the type of base resin.

[0144] On the other hand, Examples 1, Comparative Example 1, and Comparative Example 4 are examples in which HFO-1224yd was blended in a similar amount as in Comparative Examples 11-13, but the type of base resin was different. The main components of the base resins used in Examples 1, Comparative Example 1, and Comparative Example 4 were styrene-acrylonitrile copolymer, polystyrene, and styrene-methyl methacrylate copolymer, respectively. Example 1 can be said to have a particularly high HFO retention rate compared to Comparative Examples 1 and 4. The above trend was not observed when HFO-1336mzz was used, as described above for Comparative Examples 11-13. As can be seen from the above explanation, HFO-1224yd can be said to have a particularly high long-term thermal insulation effect when used in the manufacture of extruded foam boards using styrene-acrylonitrile copolymer as the base resin. It was also confirmed that Comparative Examples 11-13, which blended HFO-1336mzz, had inferior heat resistance compared to Example 1, which blended a similar amount of HFO-1224yd.

Claims

1. The process involves extruding and foaming a foamed molten resin composition containing a base resin containing a styrene-acrylonitrile copolymer, a flame retardant, and a physical blowing agent, and then molding it into a sheet using a molding tool, 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 method for producing thermoplastic resin extruded foam boards, The content of the acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base resin is 10% by mass or more and 40% by mass or less. The physical foaming agent comprises 1-chloro-2,3,3,3-tetrafluoropropene, The amount Ah of 1-chloro-2,3,3,3-tetrafluoropropene blended per 1 kg of the base resin is 0.4 mol or more and 1.3 mol or less. A method for manufacturing extruded foam boards made from thermoplastic resin.

2. The content of the acrylonitrile component derived from the styrene-acrylonitrile copolymer in the base resin is 20% by mass or more. A method for producing a thermoplastic resin extruded foam board according to claim 1.

3. 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. A method for producing a thermoplastic resin extruded foam board according to claim 1.

4. 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. A method for producing a thermoplastic resin extruded foam board according to claim 3.

5. The physical blowing agent further comprises an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms. The sum of the amount Ah of 1-chloro-2,3,3,3-tetrafluoropropene blended per 1 kg of the base resin and the amount Ac of the hydrocarbon blended per 1 kg of the base resin (Ah + Ac) is 0.5 mol or more, and the ratio of the amount Ah to the sum (Ah + Ac) [Ah / (Ah + Ac)] is greater than 0.

5. A method for producing a thermoplastic resin extruded foam board according to claim 1.

6. The physical foaming agent further comprises water and / or alcohol, The ratio of the amount of water and / or alcohol to the amount of 1-chloro-2,3,3,3-tetrafluoropropene Ah is 0.4 or more and 2 or less. A method for producing a thermoplastic resin extruded foam board according to claim 1.

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