Method for manufacturing polystyrene resin extruded foam boards

Abstract

To provide a method for manufacturing a polystyrene-based resin extrusion foam plate which can suppress variations in the number of bubbles and variations in a bubble deformation rate, while achieving both flame retardancy and heat stability.SOLUTION: There is provided a method for manufacturing a polystyrene-based resin extrusion foam plate, wherein a bubble regulator contains a talc, an addition amount of the talc with respect to 100 pts.wt. of a base material resin exceeds 0.5 pts.wt. and 5 pts.wt. or less, an addition amount of a flame retardant with respect to 100 pts.wt. of the base material resin is 0.5 to 10 pts.wt., the flame retardant contains a composite flame retardant composed of a compound having 2,3-dibromo-2-alkylpropyl group and a compound having a 2,3-dibromopropyl group, an addition amount of the composite flame retardant with respect to 100 pts.wt. of the base material resin is 0.5 to 10 pts.wt., a foamable molten resin composition contains poly (1,4-diisopropylbenzene), and an addition amount of poly (1,4-diisopropylbenzene) with respect to 100 pts.wt. of the base material resin is 0.01 pts.wt. or more and 1.5 pts.wt. or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Conventionally, a method is known in which a foam regulator is added to a polystyrene resin material, which is heated, melted, and kneaded in an extruder, then a physical foaming agent is injected under pressure into the extruder and kneaded further, these molten mixtures are extruded from a high-pressure area to a low-pressure area (usually into the atmosphere), and then shaped into a plate by a shaping device connected to the die outlet of the extruder to obtain a high-thickness polystyrene resin extruded foam (hereinafter also referred to as extruded foam or foam).

[0003] For extruded foam to be used as building insulation, it is required to satisfy the flammability standards for extruded polystyrene foam insulation materials described in JIS A9521:2022, for example. Therefore, flame retardants such as hexabromocyclododecane (hereinafter referred to as HBCD) have been added to extruded foam. HBCD is a versatile and excellent flame retardant that provides flame retardant effects with relatively small amounts. However, there are moves to regulate HBCD under the Chemical Substances Control Law and REACH, and in anticipation of its designation as a regulated substance, studies have been conducted on polystyrene resin extruded foam using superior flame retardants other than HBCD.

[0004] For example, Patent Document 1 discloses the use of a mixture of a bromine-containing organic compound having a 2,3-dibromopropyl group and a bromine-containing organic compound having a 2,3-dibromo-2-alkylpropyl group as a bromine-containing organic compound to impart flame retardancy. It is stated that by using a mixture of a bromine-containing organic compound having a 2,3-dibromopropyl group and a bromine-containing organic compound having a 2,3-dibromo-2-alkylpropyl group, an extruded foam board with excellent flame retardancy can be produced. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-82932 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, in the method for manufacturing extruded foam boards described in Patent Document 1, 100 cm 2 When attempting to manufacture extruded foam boards with such large cross-sectional areas, it can be difficult to suppress variations in air bubbles within the extruded foam board, and there was room for further improvement in this regard.

[0007] This invention has been made in view of the above circumstances, and aims to provide a method for manufacturing polystyrene resin extruded foam boards that can achieve both flame retardancy and thermal stability while suppressing variations in the number of air bubbles and variations in the rate of air bubble deformation. [Means for solving the problem]

[0008] To solve the above problems, the following method for manufacturing polystyrene resin extruded foam boards is provided.

[0009] [1] A foamable molten resin composition, which is made by kneading a base resin mainly composed of polystyrene resin, a foam regulator, a flame retardant, and a physical blowing agent, is extruded and foamed and molded into a sheet shape using a molding tool, with a cross-sectional area perpendicular to the extrusion direction of 100 cm². 2 The above method for manufacturing polystyrene resin extruded foam boards, A method for producing polystyrene resin extruded foam board, characterized in that the foam regulator contains talc, the amount of talc added per 100 parts by weight of the base resin is more than 0.5 parts by weight and 5 parts by weight or less; the flame retardant contains a composite flame retardant comprising a compound having a 2,3-dibromo-2-alkylpropyl group and a compound having a 2,3-dibromopropyl group, the amount of the composite flame retardant added per 100 parts by weight of the base resin is 0.5 parts by weight or more and 10 parts by weight or less; and the foamable molten resin composition contains poly(1,4-diisopropylbenzene), the amount of poly(1,4-diisopropylbenzene) added per 100 parts by weight of the base resin is 0.01 parts by weight or more and 1.5 parts by weight or less. [2] The polystyrene resin extruded foam board according to [1], characterized in that the ratio of the amount of talc added to the amount of poly(1,4-diisopropylbenzene) added is 7 or more. [3] The polystyrene resin extruded foam board according to [1] or [2], characterized in that the ratio of the amount of poly(1,4-diisopropylbenzene) added to the amount of the composite flame retardant added is 0.003 or more and less than 0.05. [4] A method for producing polystyrene resin extruded foam board according to [1] to [3], characterized in that the ratio of the amount of the compound having a 2,3-dibromo-2-alkylpropyl group added to the composite flame retardant to the amount of the compound having a 2,3-dibromopropyl group added is 50:50 to 80:20. [5] A method for producing polystyrene resin extruded foam board according to [1] to [4], characterized in that the physical blowing agent contains carbon dioxide, and the amount of carbon dioxide added per 1 kg of the base resin is 0.05 mol or more and 0.5 mol or less. [Effects of the Invention]

[0010] According to the method for producing polystyrene resin extruded foam boards of the present invention, it is possible to obtain polystyrene resin extruded foam boards that can achieve both flame retardancy and thermal stability while suppressing variations in the number of air bubbles and variations in the rate of air bubble deformation. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing each surface (VD surface, MD surface, TD surface) of an extruded foam board in which the bubble structure was examined in the examples.

Mode for Carrying Out the Invention

[0012] Hereinafter, an embodiment of a method for manufacturing a polystyrene-based resin extruded foam board of the present invention will be described.

[0013] The manufacturing method of the present invention is a method for manufacturing a polystyrene-based resin extruded foam board (hereinafter, also simply referred to as an extruded foam board) by a method including a step of extruding and foaming a foamable molten resin composition obtained by kneading a base resin mainly composed of a polystyrene-based resin, a bubble regulator, a flame retardant, and a physical foaming agent, and forming it into a plate shape with a molding tool.

[0014] Specifically, a base resin composed of a polystyrene-based resin and other resins added as necessary, a bubble regulator, a flame retardant, a physical foaming agent, and other additives blended as necessary are melted and kneaded under heating in an extruder to obtain a melt-kneaded product. A physical foaming agent is injected into the obtained melt-kneaded product, and it is further kneaded to obtain a foamable resin melt. This foamable resin melt is adjusted to an appropriate foaming temperature, extruded from a high-pressure extruder through a flat die into a low-pressure region to be foamed, and passed through a shaping device such as a molding die (for example, a molding die (guider) composed of two upper and lower plates of a resin such as polytetrafluoroethylene resin arranged in parallel or gently expanding from the inlet to the outlet direction) or a molding roll, whereby a plate-shaped extruded foam board is manufactured.

[0015] Furthermore, in the manufacturing method of the present invention, the foamable molten resin composition contains poly(1,4 - diisopropylbenzene).

[0016] <Base resin> (Polystyrene-based resin) Examples of the polystyrene-based resin used in the production method of the present invention include, for example, polystyrene, styrene-methyl acrylate copolymer containing 50 mol% or more of styrene unit component, styrene-ethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-polyphenylene ether copolymer, styrene-acrylonitrile copolymer, styrene-methyl styrene copolymer, styrene-dimethyl styrene copolymer, styrene-ethyl styrene copolymer, styrene-diethyl styrene copolymer, etc. One or more selected from these can be exemplified. Among these, polystyrene can be preferably used. In addition, polystyrene may contain unit components by a branching agent such as a polyfunctional monomer or a polyfunctional macromonomer in addition to the styrene unit component. The content of the styrene component unit in the above copolymer is preferably 60 mol% or more, more preferably 80 mol% or more, and still more preferably 90 mol% or more.

[0017] In addition, the base resin may contain an amorphous polyethylene terephthalate-based copolymer in order to enhance the heat insulation property of the extruded foam board. In this case, the amorphous polyethylene terephthalate-based resin is preferably blended so as to be 5% by weight or more and less than 50% by weight in the base resin, more preferably 10% by weight or more and 40% by weight or less, and still more preferably 15% by weight or more and 30% by weight or less. In addition, in the amorphous polyethylene terephthalate-based copolymer, the heat of fusion accompanying the melting of the resin based on JIS K7122 is less than 5 J / g.

[0018] Also, since the melt viscosity of the polystyrene-based resin used in the production method of the present invention is excellent in foamability and moldability, under the conditions of 200 °C and a shear rate of 100 sec -1 it is preferably 500 to 3000 Pa·s, more preferably 700 to 2500 Pa·s, and still more preferably 800 to 2000 Pa·s.

[0019] (Other polymers) The base resin may include polymers other than the polystyrene resin and the amorphous polyethylene terephthalate copolymer, to the extent that the objectives and effects of the present invention are achieved. Other polymers include thermoplastic resins such as polyethylene resins (one or more selected from the group of ethylene homopolymers and ethylene copolymers with an ethylene unit component content of 50 mol% or more), polypropylene resins (one or more selected from the group of propylene homopolymers and propylene copolymers with a propylene unit component content of 50 mol% or more), 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. These other polymers can be blended in the base resin in an amount of less than 50% by weight, preferably 30% by weight or less, more preferably 10% by weight or less, and even more preferably 5% by weight or less, depending on the purpose.

[0020] In the manufacturing method of the present invention, "base resin mainly composed of polystyrene resin" means that 50% by weight or more of the base resin is polystyrene resin. The polystyrene resin content in the base resin is preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more.

[0021] <Physical foaming agent> The physical blowing agent contained in the foamed resin molten preferably includes an early dissipation blowing agent such as carbon dioxide, water, dimethyl ether, ethyl chloride, and an aliphatic alcohol having 1 to 5 carbon atoms, and a hydrocarbon blowing agent having 3 to 5 carbon atoms.

[0022] The physical blowing agent preferably contains carbon dioxide. The amount of carbon dioxide added per 1 kg of base resin is more preferably 0.05 mol or more and 0.5 mol or less, and even more preferably 0.1 mol or more and 0.3 mol or less. When the amount of carbon dioxide added is within this range, variations in the number of bubbles and variations in the bubble deformation rate in the extruded foam board can be further suppressed.

[0023] The physical blowing agent preferably contains water. The amount of water added per 1 kg of base resin is preferably 0.05 to 0.35 mol, more preferably 0.30 mol or less, and even more preferably 0.25 mol or less. When the amount of water added is within this range, variations in the number of bubbles and variations in the bubble deformation rate in the extruded foam board can be further suppressed.

[0024] Examples of aliphatic alcohols having 1 to 5 carbon atoms 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, and 3-methyl-2-butanol. Among these, ethanol can be preferably used. Furthermore, two or more of these can be used in combination.

[0025] Suitable examples of hydrocarbon-based blowing agents with 3 to 5 carbon atoms include saturated hydrocarbons such as propane (3 carbon atoms), n-butane and isobutane (2-methylpropane) (4 carbon atoms), n-pentane and isopentane (2-methylbutane) (5 carbon atoms), neopentane (2,2-dimethylpropane), and cyclopentane. Also, examples of hydrocarbon-based blowing agents with 3 to 5 carbon atoms include fluorinated unsaturated hydrocarbons such as 1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene, 1-chloro-2,3,3,3-tetrafluoropropene, and 1,1,1,4,4,4-hexafluoro-2-butene, which have an ozone depletion potential of 0 and an extremely low global warming potential, even if they contain halogens in their molecules. These hydrocarbon-based blowing agents with 3 to 5 carbon atoms can be used individually or in combination of two or more. Among hydrocarbon-based blowing agents having 3 to 5 carbon atoms, isobutane is particularly preferred. Furthermore, the isobutane content in the hydrocarbon-based blowing agent having 3 to 5 carbon atoms is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 80 mol% or more.

[0026] Hydrocarbon-based blowing agents with 3 to 5 carbon atoms have a slower permeation rate into polystyrene resin than air, remaining in the polystyrene resin extruded foam board for a long period of time, and also have a lower thermal conductivity than air. Therefore, the resulting polystyrene resin extruded foam board has good thermal insulation properties. In addition, saturated hydrocarbon-based blowing agents with 3 to 5 carbon atoms plasticize the polystyrene resin, making it easier to adjust the melt viscoelasticity of the foamed resin molten material to a range suitable for foaming. Consequently, including a hydrocarbon-based blowing agent with 3 to 5 carbon atoms in the physical blowing agent makes it easier to obtain polystyrene resin extruded foam board with a low apparent density.

[0027] The total amount of the early-dissipating blowing agent and the hydrocarbon-based blowing agent added is preferably 0.8 mol or more and 2.0 mol or less per 1 kg of base resin. Adding 0.8 mol or more of the physical blowing agent allows the foamed resin molten material to foam to the desired apparent density required for building insulation materials. Adding 2.0 mol or less of the physical blowing agent reduces the risk of defects in the appearance of the extruded foam board. From this viewpoint, the total amount of the early-dissipating blowing agent and the hydrocarbon-based blowing agent added is more preferably 0.9 mol or more and 1.8 mol or less per 1 kg of base resin, and even more preferably 1.0 mol or more and 1.6 mol or less per 1 kg of base resin.

[0028] When the total of the early-dissipating blowing agent and the hydrocarbon-based blowing agent is set to 100 mol%, it is preferable that the physical blowing agent contains 40 mol% to 70 mol% of the early-dissipating blowing agent and 30 mol% to 60 mol% of the hydrocarbon-based blowing agent with 3 to 5 carbon atoms. By including the early-dissipating blowing agent and the hydrocarbon-based blowing agent with 3 to 5 carbon atoms within the above ranges, it is possible to obtain a polystyrene resin extruded foam board that has excellent heat insulation properties as well as excellent flame retardancy.

[0029] <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.

[0030] Flame retardants are as follows (A)(B): (A) Compounds having a 2,3-dibromo-2-alkylpropyl group, and (B) Compounds having a 2,3-dibromopropyl group The compound flame retardant comprises the following: Here, the compound flame retardant may be in the form of a mixture of two or more predetermined flame retardants, or it may contain two or more predetermined flame retardants, with each flame retardant being added separately to the base resin. By using the compound flame retardant, high flame retardancy can be imparted to the extruded foam board, the polystyrene resin is less likely to decompose during extrusion, and it becomes easy to obtain a stable extruded foam board with low apparent density (high foaming ratio).

[0031] In the manufacturing method of the present invention, the flame retardant preferably consists of 80% by weight or more of a composite flame retardant comprising (A) a compound having a 2,3-dibromo-2-alkylpropyl group and (B) a compound having a 2,3-dibromopropyl group, more preferably 90% by weight or more, and even more preferably 95% by weight or more. It is particularly preferable that the composite flame retardant consists only of (A) a compound having a 2,3-dibromo-2-alkylpropyl group and (B) a compound having a 2,3-dibromopropyl group.

[0032] Examples of compounds having a (A)2,3-dibromo-2-alkylpropyl group that constitute a composite flame retardant include tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-S-bis(2,3-dibromo-2-methylpropyl ether), and tetrabromobisphenol-F-bis(2,3-dibromo-2-methylpropyl ether). From the viewpoint of excellent flame retardant performance, the compound having a (A)2,3-dibromo-2-alkylpropyl group is preferably tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropyl ether).

[0033] Examples of compounds having a (B)2,3-dibromopropyl group that constitute the composite flame retardant include tetrabromobisphenol-A-bis(2,3-dibromopropyl ether), tetrabromobisphenol-S-bis(2,3-dibromopropyl ether), tetrabromobisphenol-F-bis(2,3-dibromopropyl ether), tris(2,3-dibromopropyl) isocyanurate, and tris(2,3-dibromopropyl) cyanurate. From the viewpoint of excellent thermal stability, the compound having a (B)2,3-dibromopropyl group that constitutes the composite flame retardant is preferably tetrabromobisphenol-A-bis(2,3-dibromopropyl ether).

[0034] The amount of composite flame retardant added is 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, and even more preferably 3 to 7 parts by weight, per 100 parts by weight of the base resin, in order to impart a high degree of flame retardancy to the extruded foam board while suppressing a decrease in extruded foaming properties and mechanical properties. Within this range, an extruded foam board with a high degree of flame retardancy can be obtained without the flame retardant inhibiting foaming properties.

[0035] In a composite flame retardant, the ratio (A:B) of the amount of compound (A) having a 2,3-dibromo-2-alkylpropyl group to the amount of compound (B) having a 2,3-dibromopropyl group is preferably 50:50 to 80:20 by weight, and more preferably 55:45 to 70:30. By keeping the ratio within this range, higher thermal stability can be imparted.

[0036] In addition to the composite flame retardants mentioned above, other flame retardants may also be used in combination, such as brominated butadiene-styrene copolymers, cresyl di2,6-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.

[0037] <Poly(1,4-diisopropylbenzene)> The amount of poly(1,4-diisopropylbenzene) (hereinafter sometimes referred to as "CCPIB") added is 0.01 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the base resin. When the amount of poly(1,4-diisopropylbenzene) added is within this range, variations in the number of bubbles and variations in the bubble deformation rate in the extruded foam board can be suppressed. In particular, even a small amount of poly(1,4-diisopropylbenzene) added (for example, 0.01 parts by weight or more) exhibits the effect of homogenizing the number of bubbles. From the above viewpoint, it is more preferable that the amount of CCPIB added is 0.02 parts by weight or more and 0.5 parts by weight or less per 100 parts by weight of the base resin. In this invention, the amount of poly(1,4-diisopropylbenzene) added during manufacturing and the amount of poly(1,4-diisopropylbenzene) in the extruded foam board can be considered to be the same amount.

[0038] The ratio of the amount of poly(1,4-diisopropylbenzene) added to the amount of composite flame retardant (CCPIB / composite flame retardant) is preferably 0.003 or more and 0.07 or less. When the ratio of the amount of poly(1,4-diisopropylbenzene) added (CCPIB / composite flame retardant) is within this range, the effect of suppressing variations in the number of bubbles and the rate of bubble deformation is obtained, and the extruded foam board becomes easier to mold. From the above viewpoint, it is more preferable that the ratio of the amount of poly(1,4-diisopropylbenzene) added to the amount of composite flame retardant (CCPIB / composite flame retardant) is 0.005 or more and less than 0.05. Note that the ratio of the amount of poly(1,4-diisopropylbenzene) added to the amount of composite flame retardant (CCPIB / composite flame retardant) is expressed as a ratio of parts by weight.

[0039] <Bubble adjusting agent> The bubble regulator contains talc, and the amount of talc added per 100 parts by weight of the base resin is between 0.5 parts by weight and 5 parts by weight. When the bubble regulator contains talc in this range, it is easy to adjust the bubble diameter and reduce the bubble diameter without impairing flame retardancy. From the above viewpoint, it is preferable that the amount of talc added per 100 parts by weight of the base resin be 0.7 parts by weight or more, more preferably 1.2 parts by weight or more, and even more preferably 1.5 parts by weight or more. On the other hand, from the viewpoint of suppressing excessively small bubble diameters, it is preferable that the amount of talc added per 100 parts by weight of the base resin be 4.5 parts by weight or less, and more preferably 4 parts by weight or less. In particular, fine talc with a 50% particle size (light transmission centrifugation method) of 0.1 to 20 μm is preferred, and fine talc with a particle size of 0.5 to 15 μm is preferred.

[0040] In addition to talc, the foam regulator may include inorganic powders such as kaolin, mica, silica, calcium carbonate, barium sulfate, clay, aluminum oxide, bentonite, and diatomaceous earth. In the production method of the present invention, it is preferable that 50% by weight or more of the foam regulator is talc, more preferably 60% by weight or more is talc, even more preferably 65% ​​by weight or more is talc, and particularly preferably 70% by weight or more is talc.

[0041] Adding talc tends to increase the number of bubbles. Furthermore, even a small amount of poly(1,4-diisopropylbenzene) contributes to uniformizing the number of bubbles. By setting the ratio of talc to poly(1,4-diisopropylbenzene) within a specific range, the foaming immediately after extrusion becomes more uniform when the foam is extruded from a high-pressure extruder to a low-pressure region through a die. Furthermore, when the foam is subsequently molded into a sheet using a molding tool, the frictional resistance between the foam and the molding tool in the width direction becomes more uniform, leading to more stable foaming and reduced variation in the number of bubbles and bubble deformation rate of the resulting foam sheet. Additionally, setting the ratio of talc to poly(1,4-diisopropylbenzene) within a specific range results in superior ease of molding and excellent extrusion stability. From the above viewpoint, the ratio of talc to poly(1,4-diisopropylbenzene) (talc / CCPIB) is preferably 7 or higher, more preferably 10 or higher, even more preferably 12 or higher, and particularly preferably 15 or higher. Furthermore, the ratio of talc added to the amount of poly(1,4-diisopropylbenzene) (talc / CCPIB) is preferably 80 or less, more preferably 70 or less, even more preferably 60 or less, and particularly preferably 50 or less. Note that the ratio of talc added to the amount of poly(1,4-diisopropylbenzene) (talc / CCPIB) is expressed in parts by weight.

[0042] <Additives> The foamed resin molten material may contain various additives. Examples of additives include heat stabilizers, flame retardants, radiation suppressants, and colorants.

[0043] Examples of heat stabilizers include one or more heat stabilizers selected from epoxy compounds, phenolic compounds, hindered amine compounds, and phosphite compounds. Preferably, the total amount of heat stabilizer added is 0.01 parts by weight or more and 30 parts by weight or less per 100 parts by weight of flame retardant.

[0044] Examples of flame retardant additives include at least one selected from diphenylalkanes, diphenylalkenes, and polyalkylbenzenes. By incorporating these, the oxygen index (the minimum concentration of oxygen required to maintain combustion of the material) of the resulting foam can be improved. Preferably, the amount of flame retardant additive added is 0.01 parts by weight or more and 20 parts by weight or less per 100 parts by weight of flame retardant.

[0045] Examples of radiation suppressants include fine powders that have a radiation suppression effect. Specifically, examples include metal oxides such as titanium oxide, metal powders such as aluminum powder, carbon such as carbon black and graphite, and ceramics. These can be used individually or in combination of two or more. The amount of radiation suppressant added is preferably 0.5 parts by weight or more and 5 parts by weight or less, and more preferably 1 part by weight or more and 4 parts by weight or less, per 100 parts by weight of the base resin.

[0046] In the manufacturing method of the present invention, as a method for blending foam regulators, flame retardants, physical foaming agents, and other additives into the base resin, a method can be employed in which a predetermined proportion of the additives is supplied together with the base resin to a supply unit provided upstream of the extruder and kneaded in the extruder. Alternatively, a method can be employed in which the additives are supplied into the molten polystyrene resin from a supply unit provided in the middle of the extruder. Specifically, a method can be employed in which a dry blend of the other additives and the base resin is supplied to the extruder and melt-kneaded, a method in which the additives and the base resin are kneaded by a kneader or the like and supplied to the extruder as a molten mixture, or a method in which a masterbatch is prepared in advance by blending a high concentration of flame retardant or other additives into a polystyrene resin, and this is supplied to the extruder and melt-kneaded with the base resin. In particular from the viewpoint of dispersibility, it is preferable to prepare a masterbatch and supply it to the extruder.

[0047] In the manufacturing method of the present invention, as described above, a molten foamable resin composition containing a base resin mainly composed of polystyrene resin, a foam regulator, a flame retardant, and a physical foaming agent is extruded and foamed under atmospheric pressure and molded into a plate shape using a molding tool to obtain a polystyrene resin extruded foam sheet.

[0048] <Physical properties of extruded foam boards> Next, we will describe the polystyrene resin extruded foam board obtained by the manufacturing method of the present invention.

[0049] (Cross-sectional area, dimensions, etc.) Furthermore, the extruded foam board of the present invention is in the form of a board. The extruded foam board has a cross-sectional area perpendicular to its extrusion direction of 100 cm². 2 That's all, 200cm 2 It is preferable that the above is true. The upper limit of the cross-sectional area is approximately 1500 cm². 2 In this specification, the area of ​​the cross-section perpendicular to the extrusion direction refers to the area of ​​the cross-section perpendicular to the extrusion direction of the foam board. The area of ​​the cross-section perpendicular to the extrusion direction is obtained by multiplying the thickness and width of the cross-section perpendicular to the extrusion direction of the extruded foam board.

[0050] The extruded foam board of the present invention can be manufactured and then cut to adjust the width, length, and possibly thickness to create a polystyrene-based resin foam insulation board.

[0051] However, if the width of the extruded foam board fluctuates significantly during manufacturing, and the width becomes narrower than specified, it becomes impossible to obtain foam insulation boards of the specified size, resulting in poor yield. Furthermore, as mentioned above, in the manufacture of extruded foam boards, foaming tends to become more difficult as the apparent density decreases and the cross-sectional area increases. According to the manufacturing method of the present invention, even when manufacturing extruded foam boards with high thickness and large cross-sectional area, it is possible to suppress variations in the number of air bubbles and variations in the air bubble deformation rate within the extruded foam board. In addition, according to the manufacturing method of the present invention, the ease of molding and extrusion stability of the extruded foam board are excellent, allowing for high yield in continuous molding.

[0052] When extruded foam board is used as thermal insulation, its thickness is preferably 20 mm or more, more preferably 30 mm or more, and even more preferably 50 mm or more. On the other hand, the upper limit of the thickness is preferably 150 mm, and more preferably 130 mm. The thickness of the extruded foam board is determined from the thickness at a position that bisects the width direction of the extruded foam board.

[0053] In the present invention, even if the widthwise length of the extruded foam board is long, it is possible to suppress variations in the number of air bubbles and variations in the rate of air bubble deformation between the widthwise edges and the center. From the above viewpoint, the width of the extruded foam board is preferably 800 mm or more, more preferably 800 mm or more, and even more preferably 850 mm or more. The upper limit is approximately 1200 mm.

[0054] (Bubble structure: average bubble diameter) The average bubble diameter of the resin extruded foam board is preferably 0.1 mm to 0.5 mm, and more preferably 0.15 mm to 0.30 mm, from the viewpoint of good mechanical strength, heat insulation, and appearance. The average bubble diameter of the polystyrene resin extruded foam board is measured as follows.

[0055] First, the extruded foam board is cut perpendicular to the extrusion direction. From the cut extruded foam board, the central part is defined as the point that bisects the width and thickness directions, respectively. The first and second ends are defined as points that bisect the thickness direction, located at a length of 10% of the width direction from each end toward the central part, and are the same length from each end toward the central part. Magnified photographs of the central part, first end, and second end are obtained using a microscope or similar device.

[0056] Next, in the resulting magnified photograph, three line segments equal in length (2 mm multiplied by the magnification factor) are drawn along the thickness direction of the extruded foam board at equal intervals, and the number of bubbles intersecting each line segment is measured. Then, the average diameter of the bubbles present on each line segment is determined by dividing the length of the line segment (the actual length of the line segment considering the magnification factor of the photograph) by the number of bubbles measured minus 1 ([number of bubbles intersecting the line segment - 1]). This measurement is performed at the center, the first end, and the second end, and the arithmetic mean of the obtained average diameters is taken as the average bubble diameter in the thickness direction of the extruded foam board.

[0057] Next, in the obtained magnified photograph, three line segments equal in length (2 mm multiplied by the magnification factor) are drawn along the width direction of the extruded foam board at equal intervals, and the number of bubbles intersecting each line segment is measured. Then, the average diameter of the bubbles present on each line segment is determined by dividing the length of the line segment (the actual length of the line segment considering the magnification factor of the photograph) by the number of bubbles measured minus 1 ([number of bubbles intersecting the line segment - 1]). This measurement is performed at the center, the first end, and the second end, and the arithmetic mean of the obtained average diameters is taken as the average bubble diameter in the width direction of the extruded foam board. The arithmetic mean of the average bubble diameter in the thickness direction and the average bubble diameter in the width direction obtained above is taken as the average bubble diameter of the extruded foam board.

[0058] (Bubble structure: Bubble deformation rate) The cell deformation ratio of the extruded foam board is preferably between 0.8 and 1.2. The cell deformation ratio is calculated by dividing the average cell diameter in the thickness direction by the average cell density in the width direction (average cell density in the thickness direction / average cell density in the width direction). The smaller the cell deformation ratio is (less than 1), the flatter the cells are; the larger the cell deformation ratio is (greater than 1), the more elongated the cells are. A cell deformation ratio within the above range provides a good balance between the mechanical strength and thermal insulation of the extruded foam board. The lower limit of the cell deformation ratio is more preferably 0.9 from the viewpoint of maintaining the compressive strength and dimensional stability of the extruded foam board. The upper limit of the cell deformation ratio is more preferably 1.1 from the viewpoint of improving thermal insulation.

[0059] (Apparent density) The apparent density of the extruded foam board is 20 to 50 kg / m 3 and preferably 30 to 45 kg / m 3 . When the apparent density is within the above range, it has sufficient mechanical strength, is excellent in lightness, and can be suitably used as, for example, a heat insulating material.

[0060] (Closed cell ratio) The closed cell ratio of the extruded foam board is preferably 85% or more, more preferably 90% or more, and even more preferably 93% or more. If the closed cell ratio is within this range, the physical foaming agent is likely to remain in the cells, and the high heat insulating performance of the foam board can be maintained over a long period. Further, a foam board excellent in mechanical strength such as compressive strength can be obtained.

[0061] The closed cell ratio of the extruded foam board is measured using a Toshiba Beckman air comparison pycnometer model 930 in accordance with procedure C of ASTM-D2856-70 (A cut sample without a formed skin cut to a size of 25 mm × 25 mm × 20 mm from the extruded foam board is placed in a sample cup for measurement. However, when the thickness is thin and a 20 mm cut sample in the thickness direction cannot be cut out, for example, two cut samples with a size of 25 mm × 25 mm × 10 mm can be placed in the sample cup simultaneously for measurement.). Using the true volume Vx of the extruded foam board (cut sample) thus measured, the closed cell ratio S (%) is calculated by the following formula (1) and obtained as the average value with N = 3.

[0062] S (%) = (Vx - W / ρ) × 100 / (VA - W / ρ) (1) Vx: The true volume (cm 3 ) of the cut sample measured by the above method (corresponding to the sum of the volume of the resin constituting the cut sample of the extruded foam board and the total volume of the closed cells in the cut sample.). VA: The apparent volume (cm 3 ) of the cut sample calculated from the outer dimensions of the cut sample used for the measurement. W: The total weight (g) of the cut sample used for the measurement. ρ: Density of the resin constituting the extruded foam board (g / cm³) 3 )

[0063] (Thermal conductivity after 5 days) In the extruded foam board of the present invention, the thermal conductivity after 5 days of manufacture is preferably 0.028 W / m·K or less, and more preferably 0.027 W / m·K or less. The thermal conductivity can be measured based on the heat flow meter method described in JIS A1412-2:1999 (single test specimen, symmetrical configuration, high temperature side 38°C, low temperature side 8°C, average temperature 23°C).

[0064] The method for producing polystyrene resin extruded foam boards of the present invention is not limited to the embodiments described above. [Examples]

[0065] The present invention will be described below with reference to examples, but the present invention is not limited in any way to these examples.

[0066] In the examples and comparative examples, the following apparatus and raw materials were used.

[0067] The extrusion apparatus used consisted of a first extruder with an inner diameter of 115 mm and a second extruder equipped with a high-kneading type screw with an inner diameter of 180 mm, connected in series. A physical foaming agent injection port was provided near the end of the first extruder, and a flat die with a resin discharge port (die lip) having a rectangular cross-section with a gap of 1 mm and a width of 440 mm was connected to the outlet of the second extruder. In addition, a molding device (guider) consisting of a pair of upper and lower plates made of polytetrafluoroethylene resin, horizontally installed at approximately constant intervals, was attached to the resin outlet of the second extruder.

[0068] (1) Base resin Polystyrene resin: DIC Corporation's polystyrene "HP-600ANJ", melt viscosity 1400 Pa·s (200℃, shear rate 100 sec) -1 )

[0069] (2) Physical foaming agent Isobutane: Manufactured by Mitsui Chemicals, Inc. water Carbon dioxide: Manufactured by Showa Carbonated Co., Ltd. Dimethyl ether: Manufactured by Mitsubishi Gas Chemical Company Ethanol: Manufactured by Yamaichi Chemical Industry Co., Ltd.

[0070] (3) Flame retardants (compound flame retardants) (A) Tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether): "SR-130" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (B) Tetrabromobisphenol A-bis(2,3-dibromopropyl ether): "SR-720" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0071] (4) Bubble regulator Talc: "High Filler #12" manufactured by Matsumura Sangyo Co., Ltd., particle size (d50) 7.5 μm

[0072] (5) Additive: Poly(1,4-diisopropylbenzene) (abbreviation: CCPIB) UNITED INITIATORS “CC-P3”

[0073] (6) Additive: Polycaprolactone (abbreviation: BC7A) "BC7A" manufactured by Suzuhiro Chemical Co., Ltd.

[0074] (Examples 1-5, Comparative Examples 1-4) The types and amounts of base resin, flame retardant masterbatch, talc (foam regulator), and CCPIB shown in Table 1 (Examples 1-4, Comparative Examples 1 and 2) were supplied to the first extruder, heated to 200°C and kneaded, and the types and amounts of physical blowing agent shown in Table 1 were supplied from the physical blowing 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 720 kg / hr, passing through the guider while foaming to form a plate (shaping) polystyrene resin extruded foam board (width: 1000 mm, length: 1820 mm, thickness: 45 mm, area of ​​cross-section perpendicular to the extrusion direction: 450 cm²). 2 ) was created.

[0075] Similarly, using the types and quantities of base resin, flame retardant masterbatch, talc (foam regulator), CCPIB, and physical blowing agent shown in Table 2 (Examples 5, Comparative Examples 3 and 4), rectangular polystyrene resin extruded foam boards (width: 950 mm, length: 1820 mm, thickness: 110 mm, cross-sectional area perpendicular to the extrusion direction: 1045 cm²) were produced. 2 They manufactured ).

[0076] [Table 1]

[0077] [Table 2]

[0078] Furthermore, the methods for measuring and evaluating the various physical properties of the extruded foam boards of Examples 1-5 and Comparative Examples 1-4 are as follows.

[0079] (Bubble structure) Measurement positions: For extruded foam board (1000 mm wide), the first and second ends were measured at positions that were 10% of the widthwise length from the end in the widthwise direction toward the center (100 mm from the end in the widthwise direction toward the center), and also at positions that bisected the thickness. The center was measured at positions that bisected both the widthwise and thicknesswise directions. Measurement of VD, MD, and TD surfaces: The measurement area was defined as a region enclosed by a 2mm x 2mm square from each direction, so that the above measurement position was in the center. As illustrated in Figure 1, the VD surface is the cross-section parallel to the extrusion direction of the extruded foam board and perpendicular to the thickness direction, the MD surface is the cross-section parallel to the extrusion direction of the extruded foam board and perpendicular to the width direction, and the TD surface is the cross-section perpendicular to the extrusion direction of the extruded foam board and parallel to the width direction. (Number of bubbles) The number of bubbles was determined by magnifying and projecting the same measurement area as the bubble structure using a microscope, and counting the total number of bubbles in the projected image within a 2mm x 2mm area. If bubbles were present on the boundary lines of a square, bubbles spanning one opposite side were included in the measurement, but bubbles spanning the other opposite side were not. This procedure was performed three times on different test specimens for each measurement area, and the arithmetic mean of these results was used as the number of bubbles for each measurement area. (Bubble diameter: Average bubble diameter (ASTM method)) The average bubble diameter was determined in accordance with ASTM D3576 as follows. First, the extruded foam board was cut perpendicular to the extrusion direction. The center was defined as the point that bisects the width and thickness directions of the cut extruded foam board, and the first and second ends were defined as points that bisect the thickness direction, located at a length of 10% of the width direction length from the ends of the width direction toward the center (100 mm from the ends toward the center). Magnified photographs of the center, first end, and second end were obtained using a microscope. Next, in the obtained magnified photographs, three line segments with lengths equal to 2 mm multiplied by the magnification factor were drawn at equal intervals along the thickness direction of the extruded foam board, and the number of bubbles intersecting each line segment was measured. Next, the average diameter of the bubbles present on each line segment was determined by dividing the length of the line segment (actual length of the line segment considering the magnification factor of the photograph) by the number of bubbles measured minus 1 ([number of bubbles intersecting the line segment - 1]). This measurement was performed on the central part, the first end, and the second end, and the arithmetic mean of the obtained average diameters was taken as the average bubble diameter in the thickness direction of the extruded foam board. Next, in the obtained magnified photograph, three line segments with lengths equal to 2 mm multiplied by the magnification factor were drawn at equal intervals along the width direction of the extruded foam board, and the number of bubbles intersecting each line segment was measured. The average diameter of the bubbles present on each line segment was calculated by dividing the length of the line segment (actual length of the line segment considering the magnification factor of the photograph) by the number of bubbles measured minus 1 ([number of bubbles intersecting the line segment - 1]). This measurement was performed at the center, the first end, and the second end, and the arithmetic mean of the obtained average diameters was taken as the average bubble diameter in the width direction of the extruded foam board. The arithmetic mean of the average bubble diameter in the thickness direction and the average bubble diameter in the width direction obtained above was taken as the average bubble diameter of the polystyrene resin extruded foam board. (Air bubble deformation rate) The bubble deformation rate was calculated for each measurement area corresponding to the bubble structure, in accordance with ASTM D3576. This involved magnifying and projecting the image, drawing vertical and horizontal lines on a 2mm x 2mm projection area, counting the number of bubbles intersecting these lines, and dividing the length of the lines by the number of bubbles to determine the bubble diameter for each measurement area. The calculation was then performed as follows: vertical bubble diameter ÷ horizontal bubble diameter. This process was repeated three times for each measurement area, and the values ​​were then calculated by taking the arithmetic mean. The bubble deformation rate for each cross-section was determined as follows. Note that the VD direction, MD direction, and TD direction refer to the thickness direction of the extruded foam board, the extrusion direction, and the width direction, respectively. The VD surface, TD surface, and MD surface are the surfaces indicated by the arrows in Figure 1. MD surface bubble deformation rate = MD surface bubble diameter in the VD direction ÷ MD direction bubble diameter TD surface bubble deformation rate = TD surface bubble diameter in the VD direction ÷ TD direction bubble diameter VD surface bubble deformation rate = VD surface bubble diameter in MD direction ÷ TD direction bubble diameter (Percentage of small bubbles: Percentage of bubbles with a diameter of 250 μm or less) For extruded foam boards, the ratio of the area occupied per unit of the foam cross-sectional area of ​​bubbles with a diameter of 250 μm or less was determined as follows. Here, bubbles with a diameter of 250 μm or less are defined as bubbles with an equivalent circular diameter of 250 μm or less. A scanning electron microscope is used to magnify the central part of the vertical cross-section perpendicular to the extrusion direction of the foam board and photograph it. From the photograph, the parts corresponding to bubbles with a diameter in the thickness direction larger than 250 μm, taking into account the magnification, are filled in black. The image is imported into an image processing device, and the area ratio of bubbles with a diameter of 250 μm or less per unit of the foam cross-sectional area is determined from the ratio of the area other than the filled-in-black parts to the total area of ​​the image. (Flame retardant) A flammability test was conducted based on C.14 Flammability Test Method A described in JIS A9521:2022. Measurements were taken by cutting out five test pieces, and the evaluation was as follows: ○ if "the flame extinguished within 3 seconds in all test pieces, there was no residue, and the material did not burn beyond the flammability limit line," and × otherwise. (Ease of molding) The following criteria were used for evaluation. A: The foaming process is extremely stable, and the surface of the extruded foam board is extremely beautiful. B: The foaming is stable, and an extremely beautiful surface can be obtained for the extruded foam board. C: The foaming is stable, and a beautiful surface can be obtained for the extruded foam board. D: Although there is some unevenness in the foaming, it is moldable, and no roughness or spots are observed on the surface of the extruded foam board. E: When attempting foam molding, resin clogs within the guider, making molding impossible, and roughness and spots are visible on the surface of the extruded foam board. (Extrusion stability) The following criteria were used for evaluation: A: During extrusion foaming, continuous and extremely stable extrusion molding into a sheet shape is possible. B: During extrusion foaming, slight variations in discharge are occasionally observed, but continuous and stable extrusion molding into a sheet shape is possible. C: During extrusion foaming, the discharge is unstable, but continuous extrusion molding is possible (not applicable). D: During extrusion foaming, the discharge is unstable, making extrusion molding impossible.

[0080] Tables 3 and 4 show the measurement results and evaluations of various physical properties of the extruded foam boards of Examples 1-5 and Comparative Examples 1-4.

[0081] [Table 3] [Table 4]

[0082] As shown in Tables 3 and 4, the extruded foam boards of Examples 1 to 5 exhibited good ease of molding, extrusion stability, flame retardancy, and thermal stability, and it was confirmed that variations in the number of air bubbles and variations in the rate of air bubble deformation were suppressed. Furthermore, it was confirmed that the small-bubble area ratio of Example 4 was 95%. On the other hand, Comparative Example 2 could not be extruded, and it was confirmed that it was difficult to suppress variations in the number of air bubbles and variations in the rate of air bubble deformation in the extruded foam boards of Comparative Examples 1, 3, and 4.

Claims

1. The process includes a step of extruding and foaming a foamable molten resin composition, which is made by kneading a base resin mainly composed of polystyrene resin, a foam regulator, a flame retardant, and a physical foaming agent, and then molding it into a sheet shape using a molding tool, with a cross-sectional area perpendicular to the extrusion direction of 100 cm². ２ The above method for manufacturing polystyrene resin extruded foam boards, A method for producing polystyrene resin extruded foam board, characterized in that the foam regulator contains talc, the amount of talc added per 100 parts by weight of the base resin is more than 0.5 parts by weight and 5 parts by weight or less; the flame retardant contains a composite flame retardant comprising a compound having a 2,3-dibromo-2-alkylpropyl group and a compound having a 2,3-dibromopropyl group, the amount of the composite flame retardant added per 100 parts by weight of the base resin is 0.5 parts by weight or more and 10 parts by weight or less; and the foamable molten resin composition contains poly(1,4-diisopropylbenzene), the amount of poly(1,4-diisopropylbenzene) added per 100 parts by weight of the base resin is 0.01 parts by weight or more and 1.5 parts by weight or less.

2. The method for producing polystyrene resin extruded foam board according to claim 1, characterized in that the ratio of the amount of talc added to the amount of poly(1,4-diisopropylbenzene) added is 7 or more.

3. A method for producing polystyrene resin extruded foam board according to claim 1 or 2, characterized in that the ratio of the amount of poly(1,4-diisopropylbenzene) added to the amount of the composite flame retardant added is 0.003 or more and less than 0.

05.

4. A method for producing polystyrene resin extruded foam board according to claim 1 or 2, characterized in that the ratio of the amount of the compound having a 2,3-dibromo-2-alkylpropyl group added to the composite flame retardant to the amount of the compound having a 2,3-dibromopropyl group added is 50:50 to 80:

20.

5. A method for producing a polystyrene resin extruded foam board according to claim 1 or 2, characterized in that the physical blowing agent contains carbon dioxide, and the amount of carbon dioxide added per 1 kg of the base resin is 0.05 mol or more and 0.5 mol or less.

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