JP2023085796A - Method for manufacturing polystyrene-based resin extruded foamed plate - Google Patents

Abstract

To provide a method for manufacturing a polystyrene-based resin extruded foamed plate which has appearance having good smoothness, can maintain low thermal conductivity, and is excellent in manufacture stability.SOLUTION: A method for manufacturing a polystyrene-based resin extruded foamed plate, which has a cross sectional area of 100 cm2 or more and apparent density of 20-50 kg/m3, includes a step of extruding a foamable resin composition obtained by kneading a base material resin containing a polystyrene-based resin as a main component, a flame retardant, and a physical foaming agent, and molding the extruded resin composition into a plate shape by a molding tool, wherein the physical foaming agent contains 1,1,1,4,4,4-hexafluoro-2-butene, and saturated hydrocarbon having 3 to 5 carbon atoms.SELECTED DRAWING: None

Description

There is an application for the application of Article 30, Paragraph 2 of the Patent Act Publisher: Japan Institute for Promoting Invention and Innovation Publication: Japan Institute for Promoting Invention and Innovation Public Technical Bulletin Public Technical Number: 2021-500600 Publication date: April 19, 2021

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

BACKGROUND ART A polystyrene-based resin extruded foam board (hereinafter also simply referred to as a "foam board") is widely used as a building heat insulating material because of its excellent heat insulating properties and mechanical strength. Such a plate-shaped foamed plate is generally produced by heating and melting a polystyrene resin in an extruder, then injecting a physical foaming agent into the resulting melt and kneading the resulting foamable molten resin kneaded product by extrusion. It is manufactured by extruding into a low-pressure region from a flat die or the like attached to the tip of the machine, foaming it, and molding it into a plate with a molding tool.

Common foaming agents used in the production of foamed boards include normal butane, isobutane, etc., which have excellent foaming properties, an ozone depletion potential of 0, a small global warming potential, and excellent heat insulation properties. of butane is used. However, these butanes are extremely flammable and remain in the foam board for a long period of time. There is an upper limit to the amount to be added.

In order to solve the above problems, in recent years, hydrofluoroolefins such as 1,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene (hereinafter also simply referred to as "HFO") A foaming agent consisting of is used (for example, Patent Documents 1 and 2). These HFOs are nonflammable, have low thermal conductivity, and can provide high heat insulation. Furthermore, it is an environmentally friendly blowing agent because it has very low ozone layer depletion potential and global warming potential.

Patent Documents 1 and 2 use 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz) alone or in combination with other foaming agents as HFO. HFO-1336mzz used in these Patent Documents 1 and 2 is excellent in the effect of keeping the thermal conductivity of the foam board low over a long period of time (long-term low thermal conductivity). Therefore, it is desired to manufacture a foamed board that can maintain low thermal conductivity by using HFO-1336mzz as a foaming agent.

Japanese Patent Publication No. 2010-522808 Japanese Patent Publication No. 2019-515112

However, when producing a foam board, if the amount of HFO-1336mzz is excessively set in order to maintain a lower thermal conductivity, the foaming agent will separate from the resin and the moldability will deteriorate. There was a problem that moldability deteriorated depending on the compounding ratio when using -1336mzz in combination with other foaming agents. In particular, these tendencies were conspicuous when trying to obtain a foam having a large cross-sectional area such as a thick foam board.

The present invention has been made in view of this background, and provides a method for producing a polystyrene-based resin extruded foam board that has an appearance with good smoothness, can maintain low thermal conductivity, and has excellent production stability. The task is to provide

According to the present invention, the following method for producing a polystyrene-based resin extruded foam board is provided.
[1] A step of extruding an expandable resin composition obtained by kneading a base resin containing a polystyrene resin as a main component, a flame retardant, and a physical blowing agent into a plate shape using a molding tool, ^and A method for producing a polystyrene-based resin extruded foam board having a cross-sectional area and an apparent density of 20 to 50 kg/m ³ ,
The physical blowing agent contains 1,1,1,4,4,4-hexafluoro-2-butene and a saturated hydrocarbon having 3 to 5 carbon atoms,
The total amount of the physical foaming agent is 1 to 1.5 mol,
The blending amount of the 1,1,1,4,4,4-hexafluoro-2-butene is 0.1 to 0.6 mol per 1 kg of the base resin,
The blending amount of the saturated hydrocarbon having 3 to 5 carbon atoms is 0.2 to 0.7 mol per 1 kg of the base resin,
The total amount of the 1,1,1,4,4,4-hexafluoro-2-butene and the saturated hydrocarbon having 3 to 5 carbon atoms is 0.6 to 1.3 mol,
The ratio (1 , 1,1,4,4,4-hexafluoro-2-butene/the saturated hydrocarbon having 3 to 5 carbon atoms) is 2 or less.
[2] In the method for producing an extruded polystyrene resin foam board according to the invention [1], the above 1, 1, 1, 4, 4 ,4-Hexafluoro-2-butene compounding amount (mol/kg) ratio (1,1,1,4,4,4-hexafluoro-2-butene compounding amount/saturated carbonization with 3 to 5 carbon atoms hydrogen content) is 1.5 or less.
[3] In the method for producing an extruded polystyrene resin foam board according to the invention [1] or [2], the physical foaming agent is water, carbon dioxide, a dialkyl ether having 1 to 3 carbon atoms in the alkyl chain, and carbon It contains one or more early fugitive foaming agents selected from aliphatic alcohols of numbers 1 to 5, and the blending amount of the early fugitive foaming agent is 0.2 mol or more per 1 kg of the base resin. and

According to the production method of the present invention, it is possible to provide a method for producing a polystyrene-based resin extruded foam board that has an appearance with good smoothness, can maintain low thermal conductivity, and has excellent production stability.

The method for producing the extruded polystyrene resin foam board of the present invention will be described in detail below.
The method for producing an extruded polystyrene resin foam board of the present invention comprises extruding an expandable resin composition obtained by kneading a base resin containing a polystyrene resin as a main component, a flame retardant, and a physical foaming agent, and forming a plate by using a molding tool. It is a method for producing a polystyrene-based resin extruded foam board including a step of molding into.

Specifically, a base resin consisting of a polystyrene resin and other resins added as necessary, a flame retardant, and other additives blended as necessary are melted and kneaded under heat in an extruder. Then, a foaming agent containing a specific HFO and a saturated hydrocarbon is pressurized into the obtained melt-kneaded product, and the mixture is further kneaded to obtain an expandable resin melt, and the expandable resin melt is adjusted to an appropriate foaming temperature, Extruded from a high-pressure extruder through a flat die to a low-pressure area to foam, and a mold placed at the exit of the flat die (for example, two upper and lower pieces installed in parallel or so as to gradually expand from the entrance to the exit direction) A shaping device (hereinafter also referred to as a guider) composed of a plate of polytetrafluoroethylene resin or the like and a molding tool such as a molding roll are arranged, and the extruded foam composition passes through the molding tool, In addition, in the present invention, by setting the blending amount and blending ratio of the specific HFO and saturated hydrocarbon described later to a specific range, the foam is shaped into a plate shape and has a large cross-sectional area. It is possible to obtain a foamed board that has a good appearance even if it is a board and that can maintain a low thermal conductivity.

<Base resin>
(polystyrene resin)
Examples of the polystyrene resin used in the production method of the present invention include 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 One or more selected from polymers, styrene-methylstyrene copolymers, styrene-dimethylstyrene copolymers, styrene-ethylstyrene copolymers, styrene-diethylstyrene copolymers, etc. can be exemplified. Among these, polystyrene can be preferably used. In addition to the styrene unit component, polystyrene may contain a unit component formed by a branching agent such as a polyfunctional monomer or a polyfunctional macromonomer. The content of styrene component units in the copolymer is preferably 60 mol % or more, more preferably 80 mol % or more, still more preferably 90 mol % or more.

The melt viscosity of the polystyrene-based resin used in the production method of the present invention is preferably 500 to 3000 Pa s, more preferably 1000 to 2500 Pa s, and still more preferably 1500 because of its excellent foamability and moldability. ~2300 Pa·s. In this specification, the melt viscosity is a value measured under conditions of a temperature of 200° C. and a shear rate of 100 sec ⁻¹ based on JIS K7199:1999.

In addition, the base resin may contain an amorphous polyethylene terephthalate-based copolymer in order to enhance the heat insulating properties of the foam board. In this case, the amorphous polyethylene terephthalate resin is preferably blended in the base resin in an amount of 5% by mass or more and less than 50% by mass, more preferably 10% by mass or more and 40% by mass or less, and even more preferably It is 15 mass % or more and 30 mass % or less. The amorphous polyethylene terephthalate-based copolymer has a heat of fusion of less than 5 J/g when the resin melts according to JIS K7122. The heat of fusion was measured using a heat flux differential scanning calorimeter based on the heat flux differential scanning calorimetry method in JIS K7122-1987, heated at a heating rate of 10 ° C. per minute to 280 ° C., and maintained at this temperature for 10 minutes. After holding, the temperature is cooled to 23°C at a cooling rate of 10°C/min, and the temperature is measured based on the DSC curve obtained by heating again to 280°C at a heating rate of 10°C/min.

The melt viscosity of the amorphous polyethylene terephthalate copolymer is preferably 500 to 3000 Pa·s, more preferably 1000 to 2500 Pa·s, still more preferably 1500 to 2300 Pa·s. From the viewpoint of compatibility with the polystyrene-based resin, the melt viscosity of the amorphous polyethylene terephthalate-based copolymer is preferably close to the melt viscosity of the polystyrene-based resin.

(Other polymers)
The base resin may contain a polymer other than the polystyrene-based resin and the amorphous polyethylene terephthalate-based copolymer within the range in which the objects and effects of the present invention are achieved. Other polymers include polyethylene-based resins (one or a mixture of two or more selected from the group of ethylene homopolymers and ethylene-based copolymers having an ethylene unit component content of 50 mol% or more), polypropylene-based resins. (one or a mixture of two or more selected from the group of propylene homopolymers and propylene copolymers having a propylene unit component content of 50 mol% or more), polyphenylene ether resins, thermoplastics such as polymethyl methacrylate Resin, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene-styrene block copolymer, styrene - thermoplastic elastomers such as ethylene copolymers; The content of these other polymers in the base resin is less than 50% by mass, preferably 30% by mass or less, more preferably 10% by mass or less, and still more preferably 5% by mass. % or less, depending on the purpose.

In the production method of the present invention, the base resin mainly composed of polystyrene resin means that 50% by mass or more of the base resin is polystyrene resin, preferably 60% by mass or more, more preferably. is 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

<Physical blowing agent>
The physical foaming agent used in the present invention is a foaming agent A composed of 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz) and a saturated hydrocarbon having 3 to 5 carbon atoms. Agent B is an essential component.

(Blowing agent A)
Foaming agent A, 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz), among hydrofluoroolefins, has moderate solubility and excellent foaming properties in polystyrene resins. It has persistence in the body and can produce a foam board with excellent long-term low thermal conductivity. In addition, since it is nonflammable, it is possible to reduce the risk of ignition due to static electricity during production of the foam board. Furthermore, it has a low ozone depletion potential, a very low global warming potential, and is a blowing agent that has a low impact on the environment. However, if the foaming agent A is excessively added, the smoothness is inhibited and the appearance may be deteriorated.

(Blowing agent B)
Examples of the saturated hydrocarbon having 3 to 5 carbon atoms of the blowing agent B include propane, normal butane, isobutane, normal pentane, isopentane, neopentane, cyclopentane, etc. These may be used alone or in combination of two or more. It can be used in combination. Among these, isobutane can be preferably used.

The saturated hydrocarbon having 3 to 5 carbon atoms, particularly isobutane, has a relatively low gas permeation rate to polystyrene resin, and thus can remain in the foam board for a relatively long period of time. Moreover, since the saturated hydrocarbon has a lower thermal conductivity than air, it can contribute to the reduction of the thermal conductivity of the extruded foam board when it remains in the cells of the foam board. However, on the other hand, it also inhibits the flame retardancy of the foam board, so it is necessary to consider the blending amount and blending ratio that achieves both flame retardancy and long-term heat insulation.

(Early release foaming agent)
In the present invention, the foaming agent A and the foaming agent B are used as essential foaming agents. It is preferred to incorporate one or more early release blowing agents selected from fatty alcohols of

Since water has a low molecular weight and high foaming efficiency, it makes it possible to reduce the apparent density of the extruded foam insulation board. In addition, the water makes it possible to reduce the burden on the environment and quickly dissipates from the foam board, so that the dimensions of the obtained foam board can be stabilized at an early stage.

Carbon dioxide can achieve a high expansion ratio without impairing the flame retardancy of the obtained extruded foam insulation board, and also has high gas permeability to the base resin, so that carbon dioxide quickly dissipates from the extruded foam insulation board. , the dimensional stability, heat insulation performance and flame retardancy of the foam insulation board can be stabilized at an early stage.

Dialkyl ethers having 1 to 3 carbon atoms in the alkyl chain and aliphatic alcohols having 1 to 5 carbon atoms do not deplete the ozone layer like water does, nor do they cause global warming. Since it dissipates early, the shape of the foam board can be stabilized early. Further, by using a dialkyl ether having an alkyl chain of 1 to 3 carbon atoms or an aliphatic alcohol having 1 to 5 carbon atoms, a foamed board having a lower apparent density (higher expansion ratio) can be obtained.

Examples of the dialkyl ether having an alkyl chain of 1 to 3 carbon atoms include dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, etc. Among these, dimethyl ether can be preferably used. Moreover, these can also be used together 2 or more types.

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, crotyl alcohol, propargyl 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., and among these, ethanol can be preferably used. Moreover, these can also be used together 2 or more types.

By blending the early dissipating foaming agent together with the foaming agent A and the foaming agent B in a specific ratio, the resin during foaming is appropriately plasticized to improve the foamability, thereby obtaining a foamed board with a low apparent density. be able to. When an early dissipation foaming agent is used together with the blowing agent A and the blowing agent B, it becomes easier to obtain a foam board with a low apparent density. It is preferable to use The molar ratio of water to the aliphatic alcohol having 1 to 5 carbon atoms (water: aliphatic alcohol having 1 to 5 carbon atoms) is preferably 65:35 to 85:15, more preferably 70:30 to 80. :20.

<Blending amount of blowing agent>
In the present invention, the total amount of the physical foaming agent compounded is 1 to 1.5 mol per 1 kg of the base resin. From the viewpoint of obtaining a foamed board that has an excellent appearance, a low apparent density, and is capable of maintaining a low thermal conductivity after a long period of time, the total amount of the physical foaming agent is added to 1 kg of the base resin. is preferably 1.1 to 1.4 mol, more preferably 1.2 to 1.4 mol or more.

Further, the blending amount of the foaming agent A is in the range of 0.1 to 0.6 mol per 1 kg of the base resin. By setting the blending amount of the foaming agent A within the above range, it is possible to maintain a low thermal conductivity especially for a long period of time among foamed boards using HFO. From the viewpoint of maintaining low thermal conductivity over a long period of time, the amount of foaming agent A compounded is preferably 0.2 mol or more, more preferably 0.3 mol or more, relative to 1 kg of the base resin. On the other hand, from the viewpoint of easily obtaining a foamed board having a low apparent density, the amount of the foaming agent A compounded is preferably 0.5 mol or less, more preferably 0.4 mol or less per 1 kg of the base resin. In the present invention, a high kneading type extruder such as a screw having a large ratio of the axial length of the screw to the diameter of the screw or a twin screw, or a first extruder and a second extruder are connected in series. In the tandem extruder, a continuous static mixing device (static mixer) is installed at the connecting portion between the first extruder and the second extruder, or the connecting portion between the second extruder and the die, if necessary. By using the foaming agent A in the above range, it is possible to easily produce an extruded foam board.

The total amount of the foaming agent A and the foaming agent B is in the range of 0.6 to 1.3 mol, preferably in the range of 0.7 to 1 mol, per 1 kg of the base resin. .

Further, the blending amount of the foaming agent B is 0.2 to 0.7 mol per 1 kg of the base resin. If the blending amount of the blowing agent B is too small, it may not be possible to obtain the desired low thermal conductivity. On the other hand, if the blending amount is too large, it may become difficult to satisfy flame retardancy. From this point of view, the amount of foaming agent B added is preferably 0.3 to 0.6 mol per 1 kg of the base resin.

Furthermore, the ratio of the blending amount (mol/kg) of foaming agent A to the blending amount (mol/kg) of foaming agent B (foaming agent A/foaming agent B) is 2 or less. In the present invention, it is important that the ratio of the blending amount of foaming agent A to the blending amount of foaming agent B satisfies the above specific ratio. Even if the foaming agent B is blended together with the foaming agent A, if the ratio of the blending amount of the foaming agent A to the foaming agent B does not satisfy the above specific ratio, the production stability is inferior, and the obtained extruded foam board is The surface smoothness of the surface and edges is poor, gas spots may occur, and the appearance may be poor. Moreover, the cell structure of the obtained extruded foam board has an excessively small cell diameter in the thickness direction, and as a result, it may be difficult to maintain a low thermal conductivity. From this point of view, the ratio of the amount of the foaming agent A to the foaming agent B is preferably 1.5 or less. On the other hand, the ratio of the compounding amount (mol/kg) of foaming agent A to the compounding amount (mol/kg) of foaming agent B (compounding amount of foaming agent A/compounding amount of foaming agent B) is 0.1 or more. is preferable, and 0.3 or more is more preferable.

In the present invention, the total blending amount of the foaming agents, the blending amount of the foaming agent A, the blending amount of the foaming agent B, and the ratio of the blending amount of the foaming agent A to the total blending amount of the foaming agent A and the foaming agent B are specified above. By setting it within the range, it is possible to obtain an extruded foam board having excellent moldability (shapeability) and good appearance even when a large amount of HFO is blended.

When an early dissipation foaming agent is used as the foaming agent together with the foaming agent A and the foaming agent B, the blending amount of the early dissipation foaming agent is preferably 0.2 mol or more per 1 kg of the base resin. The early fugitive blowing agent can improve the foamability, and since it dissipates quickly, it does not impair thermal conductivity or flame retardancy. From this point of view, the blending amount of the early fugitive foaming agent is more preferably 0.3 mol or more, more preferably 0.4 mol or more per 1 kg of the base resin. On the other hand, from the viewpoint of maintaining low thermal conductivity, the amount of the early fugitive foaming agent is preferably 0.8 mol or less, more preferably 0.7 mol or less.

<Other ingredients>
(Flame retardants)
The foam board obtained by the manufacturing method of the present invention is mainly used as a heat insulating material for building materials, and flame retardancy is imparted by blending a flame retardant with the base resin. Although the flame retardant used in the present invention is not particularly limited, it is preferable to use a brominated flame retardant. Examples of the brominated flame retardant include brominated butadiene-based polymers such as brominated butadiene-styrene copolymers, tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropyl ether), tetra Bromobisphenol-S-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-A-bis (2 ,3-dibromopropyl ether), tetrabromobisphenol-S-bis(2,3-dibromopropyl ether), tetrabromobisphenol-F-bis(2,3-dibromopropyl ether), and brominated bisphenol compounds represented by Tris (2,3-dibromopropyl) isocyanurate, mono (2,3,4-tribromobutyl) isocyanurate, di (2,3,4-tribromobutyl) isocyanurate, tris (2,3,4- Brominated isocyanurates represented by tribromobutyl) isocyanurate can be exemplified. Moreover, 1 type, or 2 or more types can be mixed and used for these brominated flame retardants.

In addition to these brominated flame retardants, cresyl di-2,6-xylenyl phosphate, antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, pentabromotoluene, isocyanuric acid, triallyl isocyanurate , Nitrogen-containing cyclic compounds such as melamine cyanurate, melamine, melam, and melem; silicone compounds; inorganic compounds such as boron oxide, zinc borate, and zinc sulfide; , ammonium polyphosphate, phosphazene, and phosphorus compounds such as hypophosphite.

Among these flame retardants, it can impart high flame retardancy, does not easily decompose polystyrene resins during extrusion, and is stable even when it has a low apparent density (high expansion ratio) and a large cross-sectional area. Tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) are combined because it becomes easy to obtain a foamed board by It is more preferable to use a combined flame retardant or a flame retardant containing a brominated butadiene-styrene copolymer.

The blending amount of the flame retardant is 0.00 per 100 parts by mass of the base resin because it can impart a high degree of flame retardancy to the foamed board and can also suppress deterioration in extrusion foamability and mechanical properties. It is preferably 1 to 10 parts by mass, more preferably 1 to 9 parts by mass, still more preferably 1.5 to 7 parts by mass. Within this range, the flame retardant does not inhibit the foamability, and the extruded polystyrene foam insulation material described in "Test Method A" specified in the flammability test method of JIS A9521: 2017 Combustibility for It is possible to obtain a foam board with a high degree of flame retardancy, such as the standard.

(flame retardant aid)
In addition, in the method of the present invention, a flame retardant auxiliary can be used together with the flame retardant for the purpose of further improving the flame retardancy of the foam board. Examples of flame retardant aids include 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3,4 -Diphenylalkanes and diphenylalkenes such as diethyl-3,4-diphenylhexane, 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-ethyl-1-pentene, poly-1,4 - One or more selected from polyalkylated aromatic compounds such as diisopropylbenzene can be exemplified. The blending amount of the flame retardant aid is generally 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part by mass, per 100 parts by mass of the base resin.

(Radiation inhibitor)
In the production method of the present invention, graphite can be blended as a radiation suppressor in the expandable resin composition in order to improve heat insulation. Graphite can improve the heat insulation of the foam board by reflecting infrared rays.

Examples of graphite include scale-like graphite, scale-like graphite, artificial graphite, earthy graphite, and the like, and it is preferable to use graphite whose main component is scale-like graphite. As will be described later, graphite is preferably used as a masterbatch in which polystyrene resin is blended at a high concentration. Graphite having a fixed carbon content of 80% or more is preferable because it has good workability when producing a masterbatch and has an excellent effect of improving the heat insulating properties of the resulting foam board. Further, in order to further improve the heat insulating properties of the foam board, the fixed carbon content is more preferably 90% or more, more preferably 95% or more. The fixed carbon content of the graphite is the value measured by the method described in JIS M8511:2014.

When graphite is blended, the amount of graphite blended is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the base resin. When the blending amount is within this range, the heat insulating properties are improved, and a foamed board having a desired low thermal conductivity can be obtained. From this point of view, the blending amount of the graphite is more preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more based on 100 parts by mass of the base resin of the foamed plate. On the other hand, from the viewpoint of maintaining the flame retardancy of the foam board, the upper limit of the graphite content is more preferably 5 parts by mass and 3 parts by mass with respect to 100 parts by mass of the base resin of the foam board. is more preferable, and 1 part by mass is particularly preferable.

Further, in the manufacturing method of the present invention, the foam board may contain a radiation suppressing agent other than the graphite in order to further improve the heat insulating properties. Radiation inhibitors other than graphite include, for example, one or more selected from metal oxides such as titanium oxide, metals such as aluminum, ceramics, carbon black, graphite, infrared shielding pigments, hydrotalcite, and the like. can be exemplified. Among these, titanium oxide can be preferably used. The amount of the radiation suppressing agent other than graphite is generally 0.5 to 5 parts by mass, more preferably 1 to 4 parts by mass, per 100 parts by mass of the base resin.

In addition, in the method of the present invention, other known additives can be appropriately added to the base resin, if necessary. Examples of other additives include various additives such as cell control agents, coloring agents such as pigments and dyes, heat stabilizers, and fillers.

(Air bubble control agent)
In the production method of the present invention, it is preferable to mix a cell control agent with the base resin to form the foamable resin composition. Inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, clay, aluminum oxide, bentonite, and diatomaceous earth can be used as the cell regulator. Among them, talc is suitable because it is easy to adjust the bubble diameter and can easily reduce the bubble diameter without impairing the flame retardancy. A fine talc of 0.5 to 15 μm is preferred. The amount of the cell control agent to be added varies depending on the type of control agent, the target cell diameter, etc., but when talc is used as the cell control agent, it is preferably 0.1 to 7 parts by mass per 100 parts by mass of the base resin. , more preferably 0.2 to 5 parts by mass, more preferably 0.3 to 3 parts by mass.

(Heat stabilizer)
Thermal stabilizers improve the thermal stability of the brominated flame retardants by adding them to raw materials and offcuts, etc., when manufacturing foamed boards or when repelletizing offcuts of foamed boards by recycling them. can be made Examples of the heat stabilizer include bisphenol type epoxy compounds such as EPICLON series manufactured by DIC, novolac type epoxy compounds, (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl ) Propionate]) and other hindered phenol compounds, (bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-diphosphite) and other phosphite compounds. Thermal stabilizers are included. It should be noted that the amount of the heat stabilizer compounded is preferably 0.1 to 40 parts by mass with respect to 100 parts by mass of the total amount of the flame retardant.

In the production method of the present invention, as a method of blending the flame retardant and other additives into the base resin, a predetermined ratio of the flame retardant and other additives together with the base resin is added to the feed section provided upstream of the extruder. and kneading in an extruder. In addition, a method of supplying the flame retardant and other additives into the molten resin from a supply section provided in the middle of the extruder can also be adopted. Specifically, a method of supplying a dry blend of a flame retardant, other additives, and a base resin to an extruder and melt-kneading them, and kneading the flame retardant, other additives, and a base resin with a kneader or the like. A method of supplying a melt-kneaded material to an extruder. A masterbatch is prepared by blending a base resin with a high-concentration flame retardant and other additives in advance, and this is supplied to an extruder and melt-kneaded with the base resin. method etc. can be adopted. In particular, from the viewpoint of dispersibility, it is preferable to adopt a method of preparing a flame retardant masterbatch and supplying it to an extruder. The flame retardant masterbatch is adjusted by using a polystyrene resin with a melt flow rate of about 0.5 to 30 g/10 minutes at 200 ° C. and a load of 5 kg as the base resin, and the flame retardant in the masterbatch is 10 to 95. It is preferably adjusted to contain 30 to 90% by mass, more preferably 50 to 85% by mass.

<Physical properties of foam board>
Next, the polystyrene-based resin extruded foam board obtained by the manufacturing method of the present invention will be described.
(cross-sectional area, dimensions, etc.)
The foamed plate of the present invention is plate-shaped and has a cross-sectional area perpendicular to the extrusion direction of 100 cm ² or more, preferably 200 cm ² or more. The upper limit of its cross-sectional area is approximately 1500 cm ² . In addition, in this specification, the cross-sectional area perpendicular to the extrusion direction refers to the area of the cross section perpendicular to the extrusion direction of the foam board.

The foamed board of the present invention is usually manufactured by preparing a base plate having a size one size or more larger than the desired size, cutting the base plate, and adjusting the width and length, and depending on the case, the thickness.

However, if the width of the base plate fluctuates greatly during production and becomes narrower than the specified width, it becomes impossible to obtain a foamed plate of the specified size, resulting in a poor yield. In the production of foamed 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 a foam board having a large thickness and a large cross-sectional area is manufactured because of excellent manufacturing stability, a foam board having a good appearance can be stably manufactured. An extruded foam board that has a good foaming state and excellent surface smoothness can be suitably used as a foam board with a molded skin without cutting the surface in the thickness direction.

In the case of a foam board used as a heat insulating material, its thickness is preferably 20 mm or more, more preferably 30 mm or more, and even more preferably 50 mm or more. On the other hand, the upper limit of thickness is preferably 150 mm, more preferably 130 mm.

Also, the width is preferably 800 mm or more, more preferably 900 mm or more. Its upper limit is approximately 1200 mm.

(apparent density)
The foam board of the present invention has an apparent density of 20-50 kg/m ³ , preferably 30-40 kg/m ³ . When the apparent density is within the above range, it can be suitably used as a heat insulating material having sufficient mechanical strength and excellent lightness.

(Closed cell rate)
The closed cell ratio of the foam plate is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more. If the closed cell ratio is within this range, the foaming agent tends to remain in the cells, and the high heat insulation performance of the foam board can be maintained over a long period of time. In addition, a foamed board having excellent mechanical strength such as compressive strength can be obtained.

The closed cell content of the extruded foam plate herein is measured according to procedure C of ASTM-D2856-70 using a Toshiba Beckman Co., Ltd. Air Comparator Type 930 Hydrometer (25 mm x 25 mm x 20 mm from the extruded foam plate). A cut sample without a molded skin cut to the size of is placed in a sample cup and measured.However, if the thickness is thin and a cut sample of 20 mm in the thickness direction cannot be cut out, for example, 25 mm × 25 mm × Two cut samples with a size of 10 mm may be placed in a sample cup at the same time and measured.) Using the true volume Vx of the extruded foam plate (cut sample), the closed cell ratio S is calculated by the following equation (1). (%) is calculated and determined as an average value of N=3.

S (%) = (Vx-W/ρ) x 100/(V _A -W/ρ) (1)
Vx: True volume (cm ³ ) of the cut sample measured by the above method (equivalent 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) .)
V _A : Apparent volume of the cut sample calculated from the outer dimensions of the cut sample used for measurement (cm ³ )
W: total weight of cut sample used for measurement (g)
ρ: Density of resin constituting extruded foam board (g/cm ³ )

(Bubble structure: Average bubble diameter in the thickness direction)
The average cell diameter in the thickness direction of the foamed plate is preferably 50 to 200 μm, more preferably 70 to 170 μm, still more preferably 80 to 150 μm. When the average cell diameter is within the above range, the thermoplastic resin foam board has even higher heat insulating properties and superior mechanical strength.

The method for measuring the average bubble diameter in the thickness direction is as follows. The average cell diameter in the thickness direction is obtained by increasing the magnification from 50 times to 200 so that the number of cells in the photograph is about 200 to 500 at a total of three locations in the center and near both ends of the cross section in the width direction of the foam board. Magnified photographs adjusted to a range of about 100% are obtained, and on each photograph, the maximum diameter of each bubble in the thickness direction is measured using the image processing software NS2K-pro manufactured by Nanosystem Co., Ltd., and these values are calculated. Each can be obtained by arithmetic averaging.

(Bubble structure: bubble deformation rate)
Further, in the thermoplastic resin foam board, it is preferable that the bubble deformation ratio is 0.7 to 1.5. The bubble deformation rate is the average bubble diameter in the thickness direction obtained by the above measurement method. Similar to the average bubble diameter in the thickness direction, an enlarged photograph of the bubble is obtained by using the image processing software NS2K-pro manufactured by Nanosystem Co., Ltd. Measure the maximum diameter of each bubble in the width direction using the , calculate the average bubble diameter in the width direction by arithmetically averaging each of these values, and divide the average bubble diameter in the thickness direction by the average bubble diameter in the width direction. When the cell deformation rate is smaller than 1, the cell is flattened, and when it is greater than 1, the cell is elongated. When the cell deformation rate is within the above range, the thermoplastic resin foam board has excellent mechanical strength and higher heat insulation. From the viewpoint of compressive strength and dimensional stability of the foam board, the lower limit of the cell deformation ratio is more preferably 0.8. In addition, the upper limit of the cell deformation rate is more preferably 1.1, more preferably 1.05, from the viewpoint of the effect of improving heat insulating properties.

(Thermal conductivity after 7 days)
In the foamed board of the present invention, the thermal conductivity 7 days after production is preferably 0.026 W/m·K or less, more preferably 0.025 W/m·K or less.

(Thermal conductivity after 100 days)
Also, the thermal conductivity 100 days after production is preferably 0.028 W/m·K or less, more preferably 0.027 W/m·K or less.

The thermal conductivity is measured based on the heat flow meter method described in JIS A1412-2: 1999 (one specimen, symmetrical configuration, high temperature side 38 ° C., low temperature side 8 ° C., average temperature 23 ° C.). can be done.

The present invention will be described in more detail below by way of examples. However, the present invention is in no way limited by the examples.

In Examples and Comparative Examples, the following apparatus and raw materials were used.

A high kneading type first extruder with an inner diameter of 115 mm and a second extruder with an inner diameter of 180 mm are connected in series, a physical foaming agent injection port is provided near the end of the first extruder, and a cross section with a gap of 1 mm × width of 440 mm is An extrusion apparatus was used in which a flat die with a rectangular resin outlet (die lip) was connected to the outlet of the second extruder. At the resin outlet of the second extruder, a molding device (guider) was attached, in which a pair of upper and lower plates made of polytetrafluoroethylene resin were horizontally arranged at substantially constant intervals.

(1) Base resin (1-1) Polystyrene resin: polystyrene “HP780AN” manufactured by DIC Corporation, melt viscosity (200° C., 100 sec ⁻¹ ) 1900 Pa·s
(1-2) Polyester resin: spiroglycol-modified polyethylene terephthalate "ALTESTER3012" manufactured by Mitsubishi Gas Chemical Co., Ltd., terephthalic acid 100% by mass, spiroglycol/ethylene glycol = 30% by mass/70% by mass, melt viscosity (200°C, 100 sec ^-1 ) 2000 Pa s
The melt viscosity is a value measured using a Capilograph 1D (manufactured by Toyo Seiki Seisakusho Co., Ltd.) flow property measuring machine under conditions of a temperature of 200° C. and a shear rate of 100 sec ⁻¹ .

(2) flame retardant (2-1) tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether): Daiichi Kogyo Seiyaku "SR-130" / tetrabromobisphenol A-bis (2,3 -Dibromopropyl ether): Daiichi Kogyo Seiyaku "SR-720" = 60% by mass / using a flame retardant masterbatch containing a 40% by mass mixed flame retardant (GR-134BG manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), The masterbatch was added so as to have the amount of flame retardant shown in the table.
(2-2) Brominated butadiene-styrene copolymer: Using a flame retardant masterbatch containing a flame retardant of Emerald Innovation 3000 (E3000) manufactured by LANXESS, the masterbatch is prepared so that the amount of flame retardant in the table is was added to

(3) Air cell regulator talc (manufactured by Matsumura Sangyo Co., Ltd., product name “High Filler #12”, particle size (d50) 7.5 μm)

(4) Radiation suppressor (4-1) Graphite (graphite: manufactured by Resinocolor Kogyo Co., Ltd., trade name: SBF-T-1683, flake graphite powder, average particle size 17 μm, 40% masterbatch)
(4-2) Titanium oxide (manufactured by Nikko Bix Co., Ltd.)

(5) Physical blowing agent (A) 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz): (B) Isobutane (C-1) manufactured by Mitsui Chemours Fluoro Products Co., Ltd. 1,3,3,3-tetrafluoropropene (HFO-1234ze): manufactured by Honeywell Japan (C-2) water (C-3) ethanol: manufactured by Yamaichi Chemical Industry Co., Ltd.

Examples 1-6, Comparative Examples 1-5
The type and amount of base resin, flame retardant masterbatch, and cell control agent shown in Table 1 below (Examples 1 to 6, Comparative Examples 1 to 5) are supplied to the first extruder, heated to 200 ° C. and kneaded. Then, from the physical foaming agent injection port provided in the first extruder, the physical foaming agent of the type and amount shown in Table 1 is supplied at each foaming agent injection pressure shown in Table 1, and further kneaded to melt the foamable resin. formed things. Next, the obtained foamable resin melt is transferred to a second extruder to adjust the resin temperature, extruded into a guider at a discharge rate of 400 kg/hr, and passed through the guider while foaming to form a plate. Molding (shaping) to produce a base plate with a thickness of 30 mm of foam board, further adjusting the width and length of the base plate by cutting, and cutting the molded skins on both sides evenly so that there is no molded skin A rectangular parallelepiped polystyrene resin foam board (width: 910 mm, length: 1820 mm, thickness: 25 mm, cross-sectional area perpendicular to the extrusion direction: 227.5 cm ² ) was produced.

For the foam plates obtained under the conditions of Examples and Comparative Examples, the cell structure (average cell diameter in the thickness direction, cell deformation rate), apparent density, closed cell rate, and thermal conductivity (after 7 days and 100 days) were measured by the following methods. Combustibility, appearance (surface smoothness (surface, edges), gas spots, shrinkage), and manufacturing stability were evaluated according to the following criteria. Table 1 shows the results.

Cell structure (average cell diameter in thickness direction)
The average bubble diameter in the thickness direction was obtained by the following method. Enlarged photographs were taken at a magnification of 100 times at a total of three locations, which are positions where the obtained foam board is divided into two equal parts in the length direction, and near the center and both ends of the vertical cross section in the width direction of the foam board. On each photograph, the maximum diameter of each bubble in the thickness direction was measured using the image processing software NS2K-pro manufactured by Nanosystem Co., Ltd., and the values were calculated by arithmetically averaging.

Bubble structure (bubble deformation rate)
For the bubble deformation rate, the maximum diameter of each bubble in the width direction is measured using the image processing software NS2K-pro manufactured by Nanosystem Co., Ltd. for enlarged photographs of bubbles in the same manner as the method for measuring the bubble diameter in the thickness direction. , and the average cell diameter in the width direction was determined by arithmetically averaging these values, and the average cell diameter in the thickness direction was divided by the average cell diameter in the width direction.

Specifically, cut samples were cut out from a total of three positions at which the obtained foam board was divided into two equal parts in the length direction, and at the center part in the width direction and near both ends in the width direction of the foam board. A cut sample was used as a measurement sample, the closed cell content was measured for each measurement sample, and the arithmetic mean value of the closed cell content at three locations was obtained. As a cut sample, a foam plate cut into a size of 25 mm long×25 mm wide×20 mm thick was used.

S (%) = (Vx-W/ρ) x 100/(Va-W/ρ) (1)
However, Vx, Va, W, and ρ in the formula are as follows.
Vx: the true volume of the cut sample (cm ³ ) obtained by measurement with the above-mentioned air-comparative hydrometer (the volume of the resin constituting the cut sample of the foam plate and the total volume of the closed cells in the cut sample) corresponds to sum.)
Va: Apparent volume of the cut sample calculated from the outer dimensions of the cut sample used for measurement (cm ³ )
W: Total mass of cut sample used for measurement (g)
ρ: Density of the resin composition constituting the foam board (g/cm ³ )

(apparent density)
The apparent density of the foam board was obtained by the following method. A rectangular parallelepiped sample of 50 mm long × 50 mm wide × 20 mm thick was cut out from the position where the obtained foam board was divided into two equal parts in the length direction, and from the center part and both ends in the width direction of the obtained foam board. The apparent density of each sample was determined by dividing the mass by the volume, and the arithmetic average value thereof was taken as the apparent density.

(Closed cell rate)
The closed cell ratio of the foam board is measured using an air comparison type hydrometer (manufactured by Toshiba Beckman Co., Ltd., air comparison type hydrometer, model: 930 type) according to procedure C of ASTM-D2856-70. It was obtained from the following formula (1) using the true volume Vx of the plate.

(Thermal conductivity: 7 days after production)
A test piece of 200 mm length × 200 mm width × 20 mm thickness was cut out from the central part in the width direction of the foam board immediately after production, and the test piece was stored in a constant temperature and humidity room at a temperature of 23 ° C. and a relative humidity of 50%. Later, each thermal conductivity was measured based on the plate heat flow meter method (two heat flow meters method, high temperature side 38° C., low temperature side 8° C., average temperature 23° C.) described in JIS A1412-2 (1999).

(Thermal conductivity: 100 days after production)
The thermal conductivity after 100 days of manufacture conforms to JIS A1486:2014, and is a value obtained by measuring the thermal conductivity of an extruded foam board subjected to test method A of the long-term change acceleration test of thermal resistance. be. Specifically, a rectangular parallelepiped of 200 mm long × 200 mm wide × 25 mm thick is cut out from the central part in the width direction of the extruded foam board immediately after production, and is further shaved evenly from both sides to a size of 200 mm long × 200 mm wide × 10 mm thick. A test piece was cut out, stored in a constant temperature and humidity room with a temperature of 23 ° C. and a relative humidity of 50%, and JIS A1412-2 (equivalent to 100 days after the production of an extruded foam board with a thickness of 25 mm) using the test piece 16 days after production. 1999), the thermal conductivity was measured based on the plate heat flow meter method (two heat flow meters, high temperature side 38°C, low temperature side 8°C, average temperature 23°C).

(Combustion quality)
The foam board immediately after production was stored in a constant temperature and humidity room with a temperature of 23 ° C. and a relative humidity of 50%, and 4 weeks after production, 5 test pieces were randomly cut out from the foam board (N = 5), The flammability was measured based on "test method A" defined in the flammability test method of 2017, and the flame retardancy of the foam board was evaluated according to the following criteria.
Evaluation criteria ◎: disappears in less than 2 seconds in all 5 test pieces ○: disappears in 2 to 3 seconds in 1 or more test pieces, disappears in 3 seconds in all 5 test pieces ×: 5 pieces The average burning time of the test piece exceeds 3 seconds (not applicable)

(Appearance: Surface smoothness (surface, edge))
The surface smoothness of the surface and edges of the base plate and the extruded foam plate was visually evaluated according to the following criteria.
◎: The surface and edges of the base plate and the extruded foam plate are extremely good ○: Roughness rarely occurs on the surface or the edge of the base plate, and the surface and edges of the extruded foam plate are extremely good △: The surface or the edge of the extruded foam plate Roughness rarely occurs on the part ×: A lot of roughness occurs on the surface or edge of the extruded foam board

(gas spot)
Gas spots (excessively large bubbles observed on the surface of the foamed plate and cross section of the foamed plate due to separation of the foaming agent generated during extrusion foaming) were evaluated according to the following criteria.
◎: No spot holes are seen in the base plate and the extruded foam plate ○: Almost no spot holes are seen in the base plate, and no spot holes are seen in the extruded foam plate △: Spot holes are part of the extruded foam plate was observed ×: Multiple spot holes were observed in the extruded foam board, and a good foam board was not obtained

(manufacturing stability)
Production stability was evaluated according to the following criteria.
◎: Stable manufacturability with no variation in the width of the original sheet 〇: Variation in the width of the original sheet is rarely seen, but there is no problem in manufacturing Not ×: difficult to mold the original plate, difficult to manufacture

From the results of each measurement and evaluation described above, 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz) (blowing agent A) as a physical blowing agent and Examples 1 to 6 using saturated hydrocarbon (isobutane) (foaming agent B) under the conditions of the present invention have good apparent density, cell structure, and thermal conductivity after 7 days and 100 days, and are combustible. And the state of appearance was also good.

On the other hand, Comparative Examples 1 to 5, in which the foaming agent was not used under the conditions of the present invention, were inferior in any of smoothness, gas spotting, and production stability, and all were inferior to Examples 1 to 6 after 7 days. , the thermal conductivity after 100 days was poor.

Claims (3)

A step of extruding an expandable resin composition obtained by kneading a base resin containing a polystyrene resin as a main component, a flame retardant, and a physical blowing agent into a plate shape using a molding tool, and forming a cross-sectional area of 100 cm ² or more. A method for producing a polystyrene-based resin extruded foam board having an apparent density of 20 to 50 kg/m ³ ,
The physical blowing agent contains 1,1,1,4,4,4-hexafluoro-2-butene and a saturated hydrocarbon having 3 to 5 carbon atoms,
The total amount of the physical foaming agent is 1 to 1.5 mol,
The blending amount of the 1,1,1,4,4,4-hexafluoro-2-butene is 0.1 to 0.6 mol per 1 kg of the base resin,
The blending amount of the saturated hydrocarbon having 3 to 5 carbon atoms is 0.2 to 0.7 mol per 1 kg of the base resin,
The total amount of the 1,1,1,4,4,4-hexafluoro-2-butene and the saturated hydrocarbon having 3 to 5 carbon atoms is 0.6 to 1.3 mol,
The ratio (1 , 1,1,4,4,4-hexafluoro-2-butene/saturated hydrocarbon having 3 to 5 carbon atoms) is 2 or less. manufacturing method. The ratio (1 , 1,1,4,4,4-hexafluoro-2-butene/amount of saturated hydrocarbon having 3 to 5 carbon atoms) is 1.5 or less. A method for producing the polystyrene-based resin extruded foam board described. The physical blowing agent comprises one or more early-dissipating blowing agents selected from water, carbon dioxide, dialkyl ethers having alkyl chains of 1 to 3 carbon atoms and aliphatic alcohols having 1 to 5 carbon atoms, 3. The method for producing an extruded polystyrene resin foam board according to claim 1, wherein the amount of the early fugitive foaming agent is 0.2 mol or more per 1 kg of the base resin.