JP2022111660A - Method for producing polystyrene-based resin extruded foam plate - Google Patents

Abstract

To provide a method for producing a polystyrene-based resin extruded foam plate capable of reducing the thermal conductivity of a foam plate.SOLUTION: There is provided a method for producing a polystyrene-based resin extruded foam plate which comprises a step of extruding and foaming a foamable resin composition obtained by kneading a base material resin composed mainly of a polystyrene-based resin and a physical foaming agent, followed by molding it into a plate shape by a molding tool, wherein the physical foaming agent contains a foaming agent (a) composed of 1-chloro-2,3,3,3-tetrafluoropropene and a foaming agent (b) composed of a saturated hydrocarbon having 3 to 5 carbon atoms; the total addition amount of the physical foaming agent is 0.8 to 1.5 mol based on 1 kg of the base material resin; the addition amount of the foaming agent (a) is 0.7 to 1.3 mol based on 1 kg of the base material resin; the addition amount of the foaming agent (b) is 0.1 mol or more based on 1 kg of the base material resin; and the ratio of the addition amount of the foaming agent (b) based on 1 kg of the base material resin to the addition amount of the foaming agent (a) based on 1 kg of the base material resin is 0.6 or less.SELECTED DRAWING: None

Description

Application for application of Article 30, Paragraph 2 of the Patent Act Issued by: Japan Institute for Promoting Invention and Innovation Publication: Japan Institute for Promoting Invention and Innovation Public Technical Bulletin Public Technical Number: 2020-500051 Publication date: January 23, 2020

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

As the foaming agent used in the production of the extruded foam board, butane such as normal butane and isobutane is used because it has excellent foaming properties, an ozone depletion potential of 0, a small global warming potential, and excellent heat insulation properties. ing. However, since these butanes are extremely flammable and remain in the extruded foam board for a long period of time to become flammable, there is an upper limit to the amount of butane to be added.

In order to solve the above flammability problem, so far, by using an early fugitive blowing agent such as water, carbon dioxide, ether, alcohol, etc. in combination with butane, even if the apparent density is low, Extruded foam boards have been manufactured with low residual amounts. Furthermore, in recent years, hydrofluoroolefins such as 1,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene have been used in combination with butane and early fugitive blowing agents. there is These hydrofluoroolefins are soluble in polystyrene-based resins and have foaming properties, so they can be used to produce extruded foam boards with low apparent densities. In addition, hydrofluoroolefin is nonflammable, has low thermal conductivity in a gaseous state, has excellent heat insulating properties, and remains in the extruded foam board for a long period of time, so that long-term heat insulating properties can be imparted.

Furthermore, hydrofluoroolefins are eco-friendly foaming agents because they have very low ozone depletion potential and global warming potential. As an extruded foamed board manufactured using the above hydrofluoroolefin, for example, foamed boards of Patent Documents 1 to 3 have been proposed.

JP 2013-82805 A JP 2015-229771 A JP 2017-95618 A

Examples of the hydrofluoroolefins that are readily available include 1,3,3,3-tetrafluoropropene (hereinafter also referred to as HFO-1234ze), 1-chloro-3,3,3-trifluoropropene (hereinafter referred to as Also referred to as HFO-1233zd) and the like.

Among these hydrofluoroolefins, HFO-1234ze has an excellent effect of keeping thermal conductivity low (low thermal conductivity) compared to HFO-1233zd, but has low solubility in polystyrene resins. If the added amount is too large, it may dissipate from the polystyrene-based resin immediately after foaming, making it impossible to obtain an extruded foam board with a low apparent density.

On the other hand, although HFO-1233zd has better foaming properties than HFO-1234ze, the effect of keeping the thermal conductivity of the extruded foam board low over a long period of time is slightly lower than that of HFO-1234ze. In some cases, the contribution to the effect of lowering the thermal conductivity may be insufficient.

The present invention uses a foaming agent containing hydrofluoroolefin to provide a method for producing a polystyrene-based resin extruded foamed board that has excellent foamability, has a good appearance, and can maintain a low thermal conductivity of the foamed board. 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 polystyrene-based resin comprising a step of extruding and foaming an expandable resin composition obtained by kneading a base resin containing a polystyrene-based resin as a main component and a physical blowing agent and molding it into a plate shape using a molding tool. A method for producing an extruded foam board, wherein the physical foaming agent is a foaming agent (a) consisting of 1-chloro-2,3,3,3-tetrafluoropropene and a saturated hydrocarbon having 3 to 5 carbon atoms. The total amount of the physical foaming agent added is 0.8 to 1.5 mol with respect to 1 kg of the base resin, and the amount of the foaming agent (a) added is the base material It is 0.7 to 1.3 mol per 1 kg of resin, the amount of the foaming agent (b) added is 0.1 mol or more per 1 kg of the base resin, and the foaming agent ( A method for producing an extruded polystyrene-based resin foam board, wherein the ratio of the amount of the foaming agent (b) added to 1 kg of the base resin to the amount of a) added is 0.6 or less.
[2] In the method for producing an extruded polystyrene resin foam board according to the above invention 1, the amount of the foaming agent (b) added is less than 0.4 mol per 1 kg of the base resin.
[3] In the method for producing an extruded polystyrene resin foam board according to the above invention 1 or 2, the amount of the foaming agent (a) added is more than 0.8 mol and not more than 1.3 mol per 1 kg of the base resin. characterized by being
[4] In the method for producing an extruded polystyrene-based resin foam board according to the inventions 1 to 3, the amount of the foaming agent (b) added to 1 kg of the base resin relative to the addition amount of the foaming agent (a) to 1 kg of the base resin is 0.4 or less.

According to the production method of the present invention, a foaming agent is used in which a hydrofluoroolefin containing 1-chloro-2,3,3,3-tetrafluoropropene as a main component and a saturated hydrocarbon such as butane are added at a specific ratio. Thus, there is provided a method for producing a polystyrene-based resin extruded foam board which has excellent foamability, has a good appearance, and can maintain a low thermal conductivity after a long period of time.

The method for producing the polystyrene-based resin extruded foam board of the present invention will be described in detail below.
The production method of the present invention includes a step of extruding and foaming an expandable resin composition obtained by kneading a base resin containing a polystyrene resin as a main component and a physical blowing agent, and molding the composition into a plate using a molding tool. is a method for producing a polystyrene-based resin extruded foam board (hereinafter also simply referred to as an extruded foam board).

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 specific foaming agent is injected into the resulting melt-kneaded product, further kneaded to obtain an expandable resin melt, the expandable resin melt is adjusted to an appropriate foaming temperature, and passed through a flat die from within a high-pressure extruder. It is extruded to a low pressure area to foam, and a mold placed at the exit of a flat die (for example, two upper and lower polytetrafluoroethylene resins installed in parallel or so as to gradually expand from the entrance to the exit direction) A plate-like extruded foam plate is manufactured by passing through a mold (guider) composed of a plate and a forming device such as a forming roll.

<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, and styrene-methyl methacrylate copolymer. Polymer, 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 coalescence, styrene-methylstyrene copolymer, styrene-dimethylstyrene copolymer, styrene-ethylstyrene copolymer, styrene-diethylstyrene copolymer, 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 the styrene component unit in the copolymer is preferably 60 mol % or more, more preferably 80 mol % or more, still more preferably 90 mol % or more.

In addition, the base resin preferably contains an amorphous polyethylene terephthalate-based copolymer in order to improve the heat insulating properties of the extruded 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 amount of heat of fusion is determined according to JIS K7122 (1987) "when measuring the heat of fusion after performing a certain heat treatment" (heating rate and cooling rate in condition adjustment of the test piece are both 10 ° C./min. ) and is measured based on a DSC curve obtained using a heat flux differential scanning calorimeter.

Further, the melt viscosity of the polystyrene resin used in the production method of the present invention is excellent in foamability and moldability, so it is 500 to 3000 Pa s under the conditions of 200 ° C. and a shear rate of 100 sec ^-1 . It is preferably 1000 to 2500 Pa·s, still more preferably 1500 to 2300 Pa·s.

(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 blowing agent used in the present invention comprises at least a blowing agent (a) consisting of 1-chloro-2,3,3,3-tetrafluoropropene (HFO-1224yd) and a saturated hydrocarbon having 3 to 5 carbon atoms. It contains a foaming agent (b) as an essential component.

HFO-1224yd (1-chloro-2,3,3,3-tetrafluoropropene), which is the foaming agent (a), has moderate solubility and excellent foamability in polystyrene-based resins among hydrofluoroolefins. , which facilitates the production of extruded foam boards with low apparent density. In addition, since HFO-1224yd is nonflammable, it is possible to reduce the risk of ignition due to static electricity during the production of extruded foam boards. Furthermore, HFO-1224yd is a blowing agent that has a low ozone depletion potential, a very low global warming potential, and a low burden on the environment. However, compared to HFO-1234ze, HFO-1224yd is more likely to dissipate from the extruded foam board and cannot keep the thermal conductivity of the extruded foam board low for a long period of time. In particular, when the amount of HFO-1224yd added increases, there is a tendency for it to escape more easily from the extruded foam board. In the present invention, by adding HFO-1224yd and a saturated hydrocarbon having 3 to 5 carbon atoms in a specific ratio, the dissipation of HFO-1224yd from the extruded foam plate is suppressed, and the saturated hydrocarbon having 3 to 5 carbon atoms is added. The thermal conductivity of the extruded foam board can be kept low after a long period of time compared to the case where hydrogen is not added.

Examples of the saturated hydrocarbon having 3 to 5 carbon atoms of the blowing agent (b) include propane, normal butane, isobutane (2-methylpropane), normal pentane, isopentane (2-methylbutane), cyclobutane, neopentane (2,2 -dimethylpropane), cyclopentane, and the like. Moreover, these can also be used together 2 or more types. Among these, isobutane can be preferably used.

(Other blowing agents)
As the physical blowing agent used in the present invention, in addition to the essential blowing agent (a) and blowing agent (b), water, carbon dioxide, alkyl chloride, aliphatic alcohol having 1 to 5 carbon atoms, carbon of alkyl chain One or more other blowing agents selected from hydrofluoroolefins having 3 or 4 carbon atoms other than dialkyl ethers having 1 to 3 numbers and HFO-1224yd can be used.

To obtain an extruded foam board having a small apparent density and a good appearance by increasing the expansion ratio of the obtained extruded foam board by using the other foaming agent together with the foaming agent (a) and the foaming agent (b). is more easily possible.

Since water and carbon dioxide can reduce the environmental load and quickly dissipate from the extruded foam board, the dimensions of the obtained extruded foam board can be stabilized at an early stage.

Examples of alkyl chlorides include methyl chloride and ethyl chloride. Alkyl chloride facilitates foaming of polystyrene-based resin, and by using it together with the foaming agent (a) and foaming agent (b), an extruded foam board having a desired apparent density can be obtained. Furthermore, since the alkyl chloride has a high permeation rate through polystyrene resin and escapes early after the production of the extruded foam board, the dimensions of the obtained extruded foam board can be stabilized at an early stage.

Aliphatic alcohols with 1 to 5 carbon atoms do not deplete the ozone layer, do not cause global warming, and are quickly dissipated from the extruded foam board, so the shape of the extruded foam board can be quickly changed. can be stabilized to The aliphatic alcohol, when used together with the foaming agent (a) and the foaming agent (b), can contribute to obtaining an extruded foam board with a low apparent density (high expansion ratio).

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. Among these, ethanol can be preferably used from the viewpoint of safety to the environment and the human body.

In the present invention, in addition to HFO-1224yd as the essential blowing agent (a), trans-1,3,3,3-tetrafluoropropene (transHFO- 1234ze), cis-1,3,3,3-tetrafluoropropene (cisHFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,1,1,4,4, 4-Hexafluoro-2-butene (HFO-1336mzz) and the like can be used. These hydrofluoroolefins also include hydrochlorofluoroolefins into which chlorine is partially introduced. These foaming agents may be used alone or in combination of two or more.

<Addition amount of blowing agent>
In the present invention, the total addition amount of the physical foaming agent is 0.8 to 1.5 mol per 1 kg of the base resin. If the amount of the physical foaming agent added is too small, the resulting extruded foam board will have a high apparent density, and it may not be possible to obtain an extruded foam board with a desired low apparent density. On the other hand, if the amount added is too large, the apparent density becomes too small, and the strength of the resulting extruded foam board is reduced, making it unusable as a heat insulating material for building materials. The appearance of the foam board may deteriorate. For this reason, the total added amount of the physical blowing agent preferably exceeds 0.9 mol, more preferably 1 mol or more. Moreover, the upper limit thereof is preferably 1.4 mol, more preferably 1.35 mol.

The amount of foaming agent (a) added is 0.7 to 1.3 mol per 1 kg of base resin. If the addition amount of the foaming agent (a) is too small, the apparent density of the resulting extruded foam board may be too high, and it may not be possible to obtain an extruded foam board with a desired low apparent density. From this point of view, the addition amount of the foaming agent (a) is preferably more than 0.8 mol per kg of the base resin, more preferably 0.9 mol or more per kg of the base resin. If it is difficult to manufacture under conditions where the amount of the foaming agent (a) added is large, a high kneading type screw such as a screw with a large ratio of the axial length to the screw diameter or a twin screw is used. It becomes easy to manufacture an extruded foam board by using it as needed. On the other hand, if the addition amount of the foaming agent (a) is too large, a large number of gas spots may occur and the appearance of the resulting extruded foam board may deteriorate. From this point of view, the addition amount of the foaming agent (a) is preferably 1.2 mol or less per 1 kg of the base resin, and more preferably 1.1 mol or less per 1 kg of the base resin.

The amount of the foaming agent (b) added is 0.1 mol or more per 1 kg of the base resin. If the amount of the foaming agent (b) added is too small, the thermal conductivity of the foamed board may not be kept low after a long period of time. From this point of view, the addition amount of the foaming agent (b) is preferably 0.15 mol or more per 1 kg of the base resin, and more preferably 0.2 mol or more per 1 kg of the base resin. On the other hand, from the viewpoint of maintaining the appearance and high flame retardancy of the foam board, the amount of the foaming agent (b) added is preferably less than 0.4 mol, more preferably less than 0.4 mol, per 1 kg of the base resin. It is 0.35 mol or less per 1 kg, more preferably 0.3 mol or less per 1 kg of the base resin.

In the present invention, the ratio of the amount of foaming agent (b) added to 1 kg of base resin to the amount of foaming agent (a) added to 1 kg of base resin is 0.6 or less. When the ratio of the added amount of the foaming agent (b) to the added amount of the foaming agent (a) is within the above range, a foamed board having a low apparent density can be obtained, and the thermal conductivity can be kept low after a long period of time. can be done. From this point of view, the ratio of the amount of the foaming agent (b) added to 1 kg of the base resin to the amount of the foaming agent (a) added to 1 kg of the base resin is preferably 0.5 or less, and preferably 0.4 or less. is more preferably 0.3 or less. On the other hand, the lower limit of the ratio is approximately 0.1.

According to the production method of the present invention, a foaming agent is used in which a hydrofluoroolefin containing 1-chloro-2,3,3,3-tetrafluoropropene as a main component and a saturated hydrocarbon such as butane are added at a specific ratio. Thereby, the thermal conductivity of the foam board can be lowered after a long period of time. Although the reason for the above is not clear, the thermal conductivity of the gas phase determined from the mole fraction of the foaming agent present in the cells of the foamed plate after a long period of time is higher than that of the saturated hydrocarbon added at a specific ratio. is calculated to be low.

Other blowing agents other than the blowing agent (a) and the blowing agent (b) include water, carbon dioxide, alkyl chlorides, aliphatic alcohols having 1 to 5 carbon atoms, dialkyl ethers having 1 to 3 carbon atoms in the alkyl chain, and When one or more blowing agents selected from hydrofluoroolefins having 3 or 4 carbon atoms other than HFO-1224yd are added, they are each preferably 0.3 mol or less, preferably 0.2 mol, per 1 kg of the base resin. The following are more preferable, and 0.1 mol or less is even more preferable.

<Other ingredients>
(Flame retardants)
The extruded foam board obtained by the production 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, brominated flame retardants are preferred. 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), tetrabromobisphenol -S-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-A-bis (2,3 -dibromopropyl ether), tetrabromobisphenol-S-bis(2,3-dibromopropyl ether), brominated bisphenol compounds represented by tetrabromobisphenol-F-bis(2,3-dibromopropyl ether), tris ( 2,3-dibromopropyl)isocyanurate, mono(2,3,4-tribromobutyl)isocyanurate, di(2,3,4-tribromobutyl)isocyanurate, tris(2,3,4-tribromo brominated isocyanurates such as butyl isocyanurate; These brominated flame retardants can be used singly or in combination of two or more.

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, brominated butadiene-styrene copolymer, tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tetrabromobisphenol A- It is preferred to use a flame retardant containing one or more of bis(2,3-dibromo-2-methylpropyl ether), tris(2,3-dibromopropyl) isocyanurate. In addition, among these, high flame retardancy can be imparted, polystyrene resin is difficult to decompose during extrusion, and it has a low apparent density (high expansion ratio) and is stable even in the case of a large cross-sectional area. Since it becomes easy to obtain an extruded foam board by using a flame retardant containing a brominated butadiene-styrene copolymer, or tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and tetrabromobisphenol A -Bis(2,3-dibromo-2-methylpropyl ether) is more preferably used in combination with a flame retardant.

The blending amount of the flame retardant can impart a high degree of flame retardancy to the extruded foam board, and can also suppress the deterioration of extrusion foamability and mechanical properties. It is 0.1 to 10 parts by mass, more preferably 1 to 8 parts by mass, and still more preferably 3 to 7 parts by mass. Within this range, the flame retardant does not inhibit the foamability, and the extruded polystyrene foam insulation board described in "Test Method A" specified in the flammability test method of JIS A9521: 2017 Combustibility for It is possible to obtain an extruded foam board with a high degree of flame retardancy, such as the standard.

(flame retardant aid)
Further, in the method of the present invention, a flame retardant aid can be used together with the flame retardant for the purpose of further improving the flame retardancy of the extruded 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 polystyrene 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 extruded 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 90% 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 extruded foam board. In order to further improve the heat insulating properties of the extruded foam board, the graphite preferably has a fixed carbon content of 93% 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 (1976).

The amount of graphite compounded 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 property is improved, and an extruded foam 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 to 5 parts by mass, more preferably 0.4 to 3 parts by mass with respect to 100 parts by mass of the base resin of the extruded foam board. .

In addition, in the production method of the present invention, the extruded foam board may contain a radiation suppressing agent other than the above-mentioned 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. 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 preferable 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 the 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 weight per 100 parts by weight of the polystyrene resin. , more preferably 0.2 to 5 parts by weight, more preferably 0.3 to 3 parts by weight.

(Heat stabilizer)
Thermal stabilizers are added to raw materials and offcuts when manufacturing extruded foam boards or when repelling extruded foam board offcuts, etc., to improve the thermal stability of the above brominated flame retardants. can be improved. Examples of the heat stabilizer include bisphenol type epoxy compounds such as DIC's EPICLON series, novolac type epoxy compounds, (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) Propionate]) and other hindered phenolic compounds, (bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-diphosphite) and other phosphite compounds. 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 polystyrene 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 in advance by blending a high-concentration flame retardant and other additives with a polystyrene resin, and this is supplied to an extruder and melt-kneaded with the base resin. 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 should be adjusted so that the masterbatch contains 10 to 95% by mass of the flame retardant, using a polystyrene resin with an MFR of about 0.5 to 30 g/10 minutes as the base resin. is preferred, it is more preferably adjusted to be contained in an amount of 30 to 90% by mass, and more preferably adjusted to be contained in an amount of 50 to 85% by mass.

In the method of the present invention, the melted foamable resin composition containing the above-described base resin, additives such as flame retardants, and physical foaming agent is extruded under atmospheric pressure and foamed to form a plate-like shape using a molding tool. By molding, a polystyrene-based resin extruded foam board can be obtained.

<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.)
Also, the extruded foam board of the present invention has a plate shape. The extruded foam board preferably has a cross-sectional area perpendicular to the extrusion direction of 100 cm ² or more, more preferably 200 cm ² or more. The upper limit of its cross-sectional area is approximately 1500 cm ² .
In this specification, the cross-sectional area perpendicular to the extrusion direction refers to the area of the cross section of the extruded foam board perpendicular to the extrusion direction.

The extruded foam 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 the width becomes narrower than the specified size, it becomes impossible to obtain an extruded foam board of the specified size, resulting in a poor yield. In addition, in the production of extruded foam boards, as described above, foaming tends to become more difficult as the apparent density decreases and the cross-sectional area increases. According to the production method of the present invention, even when producing an extruded foam board having a large thickness and a large cross-sectional area, it is possible to stably produce an extruded foam board with a good appearance.

When the extruded foam board is used as a heat insulating material, its thickness is preferably 10 to 150 mm, more preferably 15 to 120 mm.

The width of the extruded foam board is preferably 800 mm or more, more preferably 900 mm or more. Its upper limit is approximately 1200 mm.

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

(Closed cell rate)
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 foaming agent (a) and the foaming agent (b) are likely to stay in the cells, and the extruded foam board can maintain high heat insulation performance over a long period of time. In addition, an extruded foam board having excellent mechanical strength such as compressive strength can be obtained.

(Thermal conductivity)
(7 days later)
In the extruded foam board of the present invention, the thermal conductivity 7 days after production is preferably 0.025 W/m·K or less, more preferably 0.023 W/m·K or less, and still more preferably 0.021 W/m.・K or less.
(after 100 days)
Also, the thermal conductivity 100 days after production is preferably 0.027 W/m·K or less, more preferably 0.026 W/m·K or less, and still more preferably 0.025 W/m·K or less.
(after 300 days)
Also, the thermal conductivity 300 days after production is preferably 0.030 W/m·K or less, more preferably 0.028 W/m·K or less, and still more preferably 0.026 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 specimen, symmetrical configuration, high temperature side 38°C, low temperature side 8°C, average temperature 23°C). . A specific measuring method will be described in Examples.

In addition, the long-term thermal conductivity is measured on a sample subjected to an accelerated test described in test method A of long-term change accelerated test of thermal resistance in accordance with JIS A1486 (2014). According to this method, for example, a sample obtained by slicing an extruded foam board with a thickness of 25 mm to a thickness of 10 mm, the thermal conductivity measured 16 days after production is the same as the heat conductivity after about 100 days after the production of the extruded foam board. The thermal conductivity, which corresponds to the conductivity, measured 80 days after production corresponds to the thermal conductivity of the extruded foam board approximately 300 days after production.

(Residual amount of foaming agent)
The extruded foamed board of the present invention can be obtained by extrusion foaming using the foaming agent (a) and the foaming agent (b), as described above, so that the extruded foamed board contains 1-chloro-2,3,3,3- A specific amount of tetrafluoropropene remains. The residual amount of the foaming agent (a) in the extruded foam board in the present invention is a value measured by an internal standard method using a gas chromatograph. Specifically, a sample of the extruded foam plate is placed in a sample bottle with a lid containing an appropriate amount of toluene and an internal standard substance, and the lid is closed. The residual amount of the foaming agent (a) in the extruded foam board can be determined by performing gas chromatographic analysis using the solution dissolved therein as a sample for measurement.

In the extruded foam board according to the present invention, the residual amount of the foaming agent (a) is preferably 0.6 mol or more per 1 kg of the extruded foam board after 7 days from production, and 0.5 mol or more after 100 days. . If the residual amount is within this range, the foaming agent (a) and the foaming agent (b) exhibit the effect of improving the heat insulating property, and the extruded foam board having excellent heat insulating property is obtained.
In the extruded foam board according to the present invention, the ratio (%) of the residual amount of the foaming agent (a) after 100 days after production to the residual amount of foaming agent (a) after 7 days after production is 70% or more. is preferred.

(compressive strength)
The extruded foam board according to the present invention has excellent compressive strength 7 days after production. In particular, when an amorphous polyethylene terephthalate-based copolymer is included as a base resin together with a polystyrene-based resin, satisfying the composition of the blowing agent of the present invention provides the effect of improving the compressive strength. The compressive strength of the extruded foam board is measured as follows.
In accordance with JIS K7181 (2011), for example, using a Tensilon universal material testing machine manufactured by A&D Co., Ltd., it can be measured by the following method. A test piece cut out from the central portion of the extruded foam, excluding the skin layer, is compressed by 10% at a speed of 10 mm/min to obtain a stress-strain curve. The stress at 10% compression is read from the resulting stress-strain curve and divided by the compression area of the test piece to obtain the 10% compression strength. However, the stress-strain curve indicates the yield point before reaching the target strain amount, and if the yield point stress is greater than the stress corresponding to the target strain amount, the compressive strength of the target strain amount is the yield point stress shall be calculated based on The compressive strength in the present invention is obtained by performing the above measurements in each of the extrusion direction, width direction, and thickness direction of the extruded foam board and averaging the results.

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

(1) Base resin polystyrene resin: polystyrene “HP780AN” manufactured by DIC Corporation, melt viscosity (200° C., 100 sec ⁻¹ ) 1900 Pa·s
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, 100sec ^-1 ) 2000Pa・s

(2) Physical blowing agent (a-1) 1-chloro-2,3,3,3-tetrafluoropropene (HFO-1224yd): manufactured by AGC (a-2) 1-chloro-3,3,3- Trifluoropropene (HFO-1233zd): Honeywell Japan Co., Ltd. (b) Isobutane: Taiyo Liquefied Gas Co., Ltd. (c-1) Water (c-2) Ethanol: Yamaichi Chemical Industry Co., Ltd.

(3) Flame retardant Tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether): Daiichi Kogyo Seiyaku "SR-130" / Tetrabromobisphenol A-bis (2,3-dibromopropyl ether) : Using a flame retardant masterbatch (GR-134BG manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) containing 82% by mass of a mixed flame retardant of Daiichi Kogyo Seiyaku "SR-720" = 60% by mass / 40% by mass, the master Batches were added to achieve the amounts of flame retardant listed in the table.

(4) Air cell regulator talc (manufactured by Matsumura Sangyo Co., Ltd., product name “High Filler #12”)
(5) Radiation suppressor graphite ("CP-N" (flaky graphite) manufactured by Nippon Graphite Industry Co., Ltd., primary particle size (d50) = 10 µm)
Titanium oxide (“JR-405” manufactured by Tayka Co., Ltd., primary particle size (d50) = 0.2 μm)

Examples 1-6, Comparative Examples 1-4
Base resin, flame retardant masterbatch, talc (cell control agent) and A radiation suppressing agent is supplied to the first extruder, heated to 200 ° C. and kneaded, and the type and amount of the physical blowing agent shown in Tables 1 and 2 are injected from the physical blowing agent injection port provided in the first extruder. was fed and further kneaded to form a foamable resin melt. 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 of extruded foam plate with a thickness of 30 mm, further adjusting the width and length of the base plate by cutting, and equally cutting the molded skins on both sides to have a 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.

Regarding the extruded foam boards obtained in Examples and Comparative Examples, apparent density, closed cell ratio, thermal conductivity (after 7 days, 100 days, 300 days), residual HFO amount (after 7 days, 100 days), residual HFO rate, Compressive strength was measured by the following method, and combustibility and appearance were evaluated according to the following criteria.

(apparent density)
The apparent density of the extruded foam board was determined as follows. A rectangular parallelepiped sample of 50 mm long × 50 mm wide × 25 mm thick is cut out from the center and both ends of the obtained extruded foam board, the mass is measured, and the mass is divided by the volume. Apparent densities of the samples were determined, and the arithmetic average value thereof was taken as the apparent density.

(Closed cell rate)
The closed cell content 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 Extrusion It was obtained from the following formula (1) using the true volume Vx of the foam board.

Specifically, cut samples are cut out from a total of three locations in the width direction center and near the width direction both ends of the extruded foam board, each cut sample is used as a measurement sample, and the closed cell ratio is measured for each measurement sample. Then, an arithmetic mean value of closed cell ratios at three locations was obtained. As a cut sample, an extruded foam plate cut into a size of 25 mm long×25 mm wide×25 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 extruded foam plate and the total volume of the closed cells in the cut sample) equivalent to the sum of
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 extruded foam board (g/cm ³ )

(Thermal conductivity after 7 days of manufacture)
A test piece 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 plate immediately after production, and the test piece is stored in a constant temperature and humidity room at a temperature of 23 ° C. and a relative humidity of 50%. After a day, the 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 after 100 days and 300 days after manufacture)
In addition, the thermal conductivity after 100 days and 300 days after production is based on JIS A1486 (2014), and the thermal conductivity is measured for the extruded foam board subjected to test method A of the long-term change acceleration test of thermal resistance. is the value obtained by 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 and stored in a constant temperature and humidity room with a temperature of 23 ° C. and a relative humidity of 50%. Equivalent to 300 days after production) using a test piece of JIS A1412-2 (1999) described in the flat plate heat flow meter method (two heat flow meters method, high temperature side 38 ° C., low temperature side 8 ° C., average temperature 23 ° C.) Thermal conductivity was measured based on

(Remaining amount of HFO after 7 days of production)
A test piece of 200 mm × 200 mm × 25 mm is cut out from the central part in the width direction of the extruded foam board immediately after production, and the test piece is stored in a constant temperature and humidity room at a temperature of 23 ° C. and a relative humidity of 50%. A suitable amount of sample was cut from the piece, placed in a sample bottle with a lid containing an appropriate amount of toluene and an internal standard substance, and the lid was closed. Using the obtained solution as a sample for measurement, gas chromatographic analysis was performed to determine the residual amount of HFO in the extruded foam board.
(HFO residual amount after 100 days of production)
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 furthermore, by evenly shaving from both sides, a test piece of 200 mm long × 200 mm wide × 10 mm thick is cut out. The test piece is stored in a constant temperature and humidity room at a temperature of 23 ° C. and a relative humidity of 50%, and an appropriate amount of sample is cut from the test piece 16 days after production (equivalent to 100 days after production of an extruded foam board with a thickness of 25 mm). After putting it in a sample bottle with a lid containing an appropriate amount of toluene and an internal standard substance and closing the lid, it was thoroughly stirred and gas chromatograph analysis was performed using a solution obtained by dissolving the HFO in the extruded foam plate in toluene as a measurement sample. Then, the amount of HFO remaining in the extruded foam board was obtained.

(HFO residual rate)
The HFO residual ratio was obtained by dividing the HFO residual amount after 7 days of production by the HFO residual amount after 100 days.

(Combustion quality)
The extruded foam plate immediately after production was stored in a constant temperature and humidity room with a temperature of 23 ° C. and a relative humidity of 50%. Flammability was measured based on "test method A" defined in A9521:2017 Flammability Test Method, and flame retardancy of the extruded foam board was evaluated according to the following criteria.
Evaluation Criteria ◯: Disappears within 3 seconds in all five test pieces.
x: The average burning time of 5 test pieces exceeds 3 seconds. (N/A)

(compressive strength)
The compressive strength of the extruded foam board was measured as follows. Based on JIS K7181 (2011), it was carried out by the following method using a Tensilon universal material testing machine manufactured by A&D Co., Ltd. A test piece (extrusion direction 50 mm x width direction 50 mm x thickness 25 mm [excluding skin layer]) obtained by cutting out from the central part of the extruded foam plate was compressed by 10% at a speed of 10 mm / min to obtain a stress-strain curve. . The stress at 10% compression was read from the obtained stress-strain curve and divided by the compression area (25 cm ² ) of the test piece to obtain the 10% compression strength. The above measurements were performed in each of the three directions of the extruded foam board, ie, the extrusion direction, width direction, and thickness direction, and the arithmetic average value was taken as the compressive strength.

(exterior)
Appearance was evaluated according to the following criteria.
⊚: The foamed state was good, and the surface of the base plate had no roughness or spot holes.
○: Roughness was observed on part of the surface of the base plate, but the foaming state was good, there were no spot holes on the surface, and an extruded foam plate with a good appearance was obtained by scraping the molded skin of the base plate. . x: Roughness, spot holes, etc. were observed on the surface of the base plate, and a good extruded foam plate could not be obtained.

From the above results, Comparative Examples 1 and 4, in which isobutane was not added, had lower HFO residual amount and HFO residual ratio after 100 days than Examples 1 to 6, and Comparative Example 1 also had low compressive strength. rice field. In addition, in Comparative Example 2 in which the amount of HFO-1224yd was increased and isobutane was not added, and in Comparative Example 3 in which the balance of the amount of HFO-1224yd and isobutane added was outside the scope of the present invention, the moldability of the extruded foam board A good extruded foam board could not be obtained because the surface was rough and had a plurality of spot holes. Moreover, in Comparative Examples 2 and 3, no good extruded foam board was obtained, so the evaluation of combustibility and the measurement of compressive strength were not performed.
On the other hand, extrusion foaming of Examples 1 to 6 was produced by using a base resin mainly composed of polystyrene resin and adding HFO-1224yd and isobutane as physical blowing agents within the range specified in the present invention. The plate was well balanced in all evaluations of apparent density, thermal conductivity, compressive strength value, combustibility and appearance.

Claims (4)

A polystyrene-based resin extruded foam board including a step of extruding and foaming an expandable resin composition obtained by kneading a base resin containing a polystyrene-based resin as a main component and a physical foaming agent, and molding it into a plate using a molding tool. A manufacturing method of
The physical blowing agent comprises a blowing agent (a) consisting of 1-chloro-2,3,3,3-tetrafluoropropene and a blowing agent (b) consisting of a saturated hydrocarbon having 3 to 5 carbon atoms,
The total amount of the physical foaming agent added is 0.8 to 1.5 mol with respect to 1 kg of the base resin,
The amount of the foaming agent (a) added is 0.7 to 1.3 mol per 1 kg of the base resin,
The amount of the foaming agent (b) added is 0.1 mol or more per 1 kg of the base resin,
A polystyrene resin extrusion characterized in that the ratio of the amount of the foaming agent (b) added to 1 kg of the base resin to the amount of the foaming agent (a) added to 1 kg of the base resin is 0.6 or less. A method for manufacturing a foam board. 2. The method for producing an extruded polystyrene resin foam board according to claim 1, wherein the amount of said foaming agent (b) added is less than 0.4 mol per 1 kg of said base resin. 3. The polystyrene resin extruded foam board according to claim 1 or 2, wherein the amount of the foaming agent (a) added is more than 0.8 mol and 1.3 mol or less per 1 kg of the base resin. Production method. 2. The ratio of the amount of the foaming agent (b) added to 1 kg of the base resin to the amount of the foaming agent (a) added to 1 kg of the base resin is 0.4 or less. 4. The method for producing the polystyrene-based resin extruded foam board according to any one of 3.