JP7224195B2 - Polystyrene resin extruded foam board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polystyrene-based resin extruded foam board.

Polystyrene-based resin extruded foam boards used for building materials and other applications are required to have a high level of flame retardancy that satisfies the flammability standards for extruded polystyrene foam heat insulating boards specified in JISA9511 (2009), for example.

As a method of imparting flame retardancy to an extruded polystyrene resin foam board, for example, a method of blending a flame retardant and using a nonflammable gas as a physical foaming agent is disclosed (see Patent Document 1). Further, an extruded foam board manufactured using a foaming agent containing a flame retardant, a nonflammable gas as a physical foaming agent, and an organic foaming agent with a high PS permeability, but not containing an organic foaming agent with a low PS permeability. is disclosed (see Patent Document 2).

JP 2018-100352 A Japanese Patent No. 5892300

In recent years, the level of flame resistance required for extruded polystyrene resin foam boards has been increasing, and extruded polystyrene resin foam boards exhibiting higher flame retardancy are being sought. Specifically, for example, even when sparks scattered by welding or the like at a construction site come into contact with a foam board, there is a demand for a high level of flame retardancy such that there is no risk of ignition.

The polystyrene-based resin extruded foam plate described in Patent Document 1 contains a relatively large amount of butane, which is a combustible gas, in the foam plate. There was a risk that the flame retardancy would be insufficient.

The extruded polystyrene-based resin foam board described in Patent Document 2 does not contain butane, which is a combustible gas, in the foam board, and has higher flame resistance. However, the foam plate described in Patent Document 2 is not intended to have flame retardancy under more severe conditions, such as contact with sparks scattered by welding or the like, and flame retardancy is insufficient under such conditions. There was a risk of becoming

The present invention has been made in view of such a background, and an object of the present invention is to provide a polystyrene-based resin extruded foam board having high flame resistance against severer conditions, especially contact with sparks.

The present invention provides a polystyrene-based resin extruded foam board described below.
<1> A polystyrene-based resin extruded foam board obtained by extruding and foaming a polystyrene-based resin using a physical foaming agent,
The physical blowing agent contains an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, a hydrofluoroolefin and another blowing agent,
The total amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms and the hydrofluoroolefin is 0.30 to 1.10 mol per 1 kg of the polystyrene resin,
The ratio of the blended amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms to the total 100 mol% of the blended amount of the physical blowing agent is 0.5 mol% or more and less than 10 mol%,
The ratio ((I)/(II)) of the apparent density (I) of the surface layer portion up to 5 mm in the thickness direction from the surface of the extruded foam board to the apparent density (II) of the entire extruded foam board exceeds 1.10. A polystyrene-based resin extruded foam board characterized by:
<2> The polystyrene-based resin extruded foam board according to <1>, wherein the other foaming agent contains one or more physical foaming agents selected from dimethyl ether, ethanol, carbon dioxide and water.
<3> The molar ratio ((A)/ (B)) is 0.5 or less, the polystyrene-based resin extruded foam board according to <1> or <2>.
<4> Any one of <1> to <3>, wherein the amount of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms is 0.05 to 0.09 mol per 1 kg of the polystyrene resin. The polystyrene-based resin extruded foam board according to 1.
<5> The polystyrene resin extruded foam board according to any one of <1> to <4>, wherein the hydrofluoroolefin is 1-chloro-3,3,3-trifluoropropene.
<6> The average cell diameter in the thickness direction of the surface layer portion up to 2 mm in the thickness direction from the surface of the extruded foam plate is 60 to 100 μm, and the average cell diameter in the thickness direction of the central portion in the thickness direction of the extruded foam plate is The extruded polystyrene resin foam board according to any one of <1> to <5>, which has a thickness of more than 100 μm.
<7> The extruded polystyrene resin foamed board according to any one of <1> to <6>, wherein the apparent density (II) of the entire extruded foamed board is 20 to 50 kg/m ³ .

The polystyrene-based resin extruded foam board of the present invention contains an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, a hydrofluoroolefin, and another foaming agent as a physical foaming agent, and has 3 carbon atoms with respect to the total amount of the physical foaming agent. By setting the blending amount of aliphatic saturated hydrocarbons of 1 to 5 to a specific ratio and setting the apparent density of the surface layer portion to the apparent density of the entire polystyrene resin foam board to a specific range, it is excellent in heat insulation and light weight. , a polystyrene-based resin extruded foam board having a high degree of flame retardancy can be obtained.

The polystyrene resin foam board of the present invention (hereinafter sometimes referred to as an extruded foam board or foam board) is a polystyrene resin foam board obtained by extruding and foaming a polystyrene resin using a physical foaming agent. , the physical blowing agent contains an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, a hydrofluoroolefin and another blowing agent.

(polystyrene resin)
The polystyrene-based resin in the present invention is a polymer mainly composed of styrene, and a styrene homopolymer or a copolymer of a vinyl-based monomer that can be copolymerized with styrene and styrene can be used. Specifically, polystyrene (GPPS), styrene-acrylonitrile copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer , styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-maleic anhydride copolymer, polystyrene-polyphenylene ether copolymer, and the like. Moreover, these polystyrene-based resins may be used in combination of two or more. The polystyrene-based resin may contain polyfunctional monomer unit components such as divinylbenzene and multi-branched macromonomers. Among these polystyrene-based resins, polystyrene is preferable from the viewpoint of expandability.

The polystyrene resin contains 50 mol % or more of styrene, preferably 60 mol % or more, more preferably 80 mol % or more, and still more preferably 90 mol % or more.

The polystyrene resin may contain other polymers as long as the objects and effects of the present invention are achieved. Other polymers include polyethylene resins (one or a mixture of two or more selected from the group of ethylene homopolymers and ethylene copolymers having an ethylene unit component content of 50 mol% or more), polypropylene. -based resin (one or a mixture of two or more selected from the group of propylene homopolymers and propylene-based copolymers having a propylene unit component content of 50 mol% or more), polyphenylene ether-based resin, polymethyl methacrylate and other thermoplastic resins, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, hydrogenated styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymer water Examples include additives, thermoplastic elastomers such as styrene-ethylene copolymers, and the like. These other polymers can be mixed depending on the purpose so as to be less than 50% by mass, preferably 30% by mass or less, in the polystyrene resin.

Moreover, in order to improve the heat insulating property of the foam board, one containing an amorphous or low-crystalline polyethylene terephthalate-based copolymer can be used. In this case, the amorphous or low-crystalline polyethylene terephthalate resin is preferably blended in the polystyrene resin in an amount of 5% by mass or more and less than 50% by mass, and 10% by mass or more and less than 30% by mass. It is more preferable to blend in

The heat of fusion of the amorphous or low-crystalline polyethylene terephthalate-based copolymer is less than 5 J/g (including 0) and less than 2 J/g (including 0) from the viewpoint of production stability of the extruded foam board. and more preferably less than 1 J/g (including 0). In addition, the heat of fusion is described in JIS K7122 (2012) "When the heat of fusion is measured after performing a certain heat treatment" (heating rate and cooling rate in condition adjustment of the test piece are both 10 ° C./ minutes) and is measured based on a DSC curve obtained using a heat flux differential scanning calorimeter (hereinafter referred to as DSC apparatus).

In addition, from the viewpoint of foamability and moldability, the polystyrene resin preferably has a melt viscosity of about 500 to 2500 Pa s, more preferably 600 to 2000 Pa s, and more preferably 700 to 1500 Pa s. It is even more preferable to have The above melt viscosity is a value measured under conditions of a temperature of 200° C. and a shear rate of 100 seconds ⁻¹ based on JIS K7199:1999.

(physical blowing agent)
The physical blowing agent in the present invention includes aliphatic saturated hydrocarbons having 3 to 5 carbon atoms, hydrofluoroolefins and other blowing agents.

[Aliphatic saturated hydrocarbon]
Examples of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms used in the present invention include propane, n-butane, isobutane, cyclobutane, n-pentane, isopentane, neopentane and cyclopentane. Among these, n-butane and isobutane are preferred, and isobutane is more preferred. These aliphatic saturated hydrocarbons having 3 to 5 carbon atoms can be used alone or in combination of two or more.

[Hydrofluoroolefin]
The present invention uses hydrofluoroolefins (HFOs) as physical blowing agents. HFO includes hydrofluoroolefins having 3 to 5 carbon atoms, specifically trans-1,3,3,3-tetrafluoropropene (transHFO-1234ze), cis-1,3,3,3-tetra fluoropropene (cisHFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1-chloro-3,3,3-trifluoropropene (HFO-1233zd) and the like. . These hydrofluoroolefins are blowing agents with low gaseous thermal conductivity, low flammability, low ozone depletion potential, and very low global warming potential (GWP). Among the above hydrofluoroolefins, trans-1,3,3,3-tetrafluoropropene (transHFO-1234ze), 1-chloro-3,3, 3-trifluoropropene (HFO-1233zd) is preferably used, and 1-chloro-3,3,3-trifluoropropene (HFO-1233zd) is more preferably used. Moreover, these hydrofluoroolefins can be used alone or in combination of two or more.

[Other blowing agents]
The other foaming agent in the present invention is not particularly limited as long ^as it is a physical foaming agent other than the ^above . is preferred. Another physical foaming agent having a polystyrene permeability within the above range is preferred because it quickly dissipates from the polystyrene-based resin and does not affect the flame retardancy and heat insulating properties of the extruded polystyrene-based resin foam board. Other foaming agents having a polystyrene permeability within the above range include, for example, dimethyl ether, ethanol, carbon dioxide, water, methyl chloride, and ethyl chloride. Among them, it is preferable that one or more physical blowing agents selected from dimethyl ether, ethanol, carbon dioxide and water are included from the viewpoint of environmental friendliness, handleability and the like. In particular, when dimethyl ether, ethanol, carbon dioxide and water are all used in combination as other physical foaming agents, the resulting polystyrene resin extruded foam board is more excellent in moldability and has a good appearance.

The polystyrene-based resin extruded foam board of the present invention uses a physical foaming agent containing an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, a hydrofluoroolefin, and another physical foaming agent as a physical foaming agent. Welding, etc. can be achieved by setting the blending amount of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms to a specific ratio to the blending amount, and setting the apparent density of the surface layer portion to the apparent density of the entire polystyrene resin foam board within a specific range. It has excellent flame retardancy even under severer conditions such as those assumed to come into contact with sparks scattered by fire.

Conventionally, when imparting flame retardancy to an extruded polystyrene resin foam board, it has been considered to use a nonflammable foaming agent such as hydrofluoroolefin as a physical foaming agent together with a flammable foaming agent such as butane. It's here. However, the conventional polystyrene-based resin extruded foam plate was not manufactured with the assumption of flame retardancy under severer conditions such as coming into contact with sparks scattered by welding or the like.

In the examples described later, even in the case of manufacturing using hydrofluoroolefin, which is a nonflammable gas, as the physical blowing agent, when the blending ratio of butane in the physical blowing agent is large, the foamed plate obtained is Although it satisfies the flammability standards stipulated in JISA9511 (2006), flame retardancy is insufficient under severer conditions such as contact with sparks scattered by welding, etc. there were.

Furthermore, even in polystyrene resin extruded foam boards manufactured using a foaming agent that does not contain butane, which is a flammable gas, as a physical foaming agent, stricter conditions such as those assumed to come into contact with sparks scattered by welding etc. The flame retardancy was insufficient.

On the other hand, the present inventors have found that C3-C5 aliphatic saturated hydrocarbons, hydrofluoroolefins and other physical blowing agents are included, and C3-C5 fats with respect to the total amount of physical blowing agents A polystyrene resin extruded foam board manufactured using a physical foaming agent with a specific proportion of the blended amount of group saturated hydrocarbon satisfies the flammability standard specified in JISA9511 (2006) and is not scattered by welding etc. It was found that it has a high degree of flame retardancy even under severer conditions such as those assumed to come into contact with sparks.

The reason why the polystyrene resin foam plate obtained by the present invention has a high degree of flame resistance even under severer conditions, such as when it is assumed that sparks scattered by welding or the like come into contact, is because the residual butane in the foam plate This is probably because the amount was small and a high-density layer with a high apparent density was formed on the surface layer of the extruded foam board. As will be described later, the extruded foam board of the present invention has a ratio ((I )/(II)) is greater than 1.10. In the present invention, by containing an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms in addition to the hydrofluoroolefin and other physical foaming agents, the obtained extruded foam board satisfies the above apparent density ratio. .

In the physical blowing agent used in the present invention, the ratio of the compounded amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms is 0.5 mol% or more and less than 10 mol% with respect to the total 100 mol% of the compounded amount of the physical blowing agent. . If the proportion of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms is less than 0.5 mol%, a high density layer with a high apparent density is not formed on the surface layer of the extruded foam board, and the extruded foam board is scattered due to welding or the like. There is a risk that flame retardancy will be insufficient under more severe conditions, such as when spark contact is assumed. In addition, when the proportion of the C 3-5 aliphatic saturated hydrocarbon compounded exceeds 10 mol%, the residual amount of the C 3-5 aliphatic hydrocarbon in the extruded foam board increases. , there is a risk of insufficient flame resistance against sparks and the like.
From the above point of view, the lower limit of the proportion of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms is preferably 3 mol% or more relative to the total 100 mol% of the physical blowing agent, and 5 mol% or more. It is more preferable to have In addition, the upper limit of the proportion of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms is preferably 9 mol% or less and 8 mol% or less with respect to the total 100 mol% of the physical blowing agent. is more preferred.

Also, the total amount of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms and the hydrofluoroolefin is 0.30 to 1.10 mol per 1 kg of the polystyrene resin. When the total amount of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms and the hydrofluoroolefin is within the above range, the resulting extruded foam board will be excellent in heat insulation, light weight, flame retardancy and the like. From the above viewpoint, the total amount is preferably 0.40 to 1.0 mol%, more preferably 0.45 to 0.80 mol%.

In the present invention, the molar ratio ((A)/ (B)) is preferably 0.5 or less. When the molar ratio ((A)/(B)) is within the above range, the flame retardance can be further enhanced under severer conditions, such as when sparks scattered by welding or the like come into contact. From the above viewpoint, the molar ratio is more preferably 0.4 or less, further preferably 0.3 or less. Also, the lower limit of the molar ratio is preferably 0.1.

In the present invention, the amount of hydrofluoroolefin compounded is preferably 0.35 to 0.80 mol per 1 kg of polystyrene resin. When the blending amount of the hydrofluoroolefin is within the above range, the flame retardancy can be further enhanced while maintaining the heat insulating properties and lightness of the extruded foam board. From the above point of view, it is more preferable that the amount of the hydrofluoroolefin compounded is 0.40 to 0.60 mol per 1 kg of the polystyrene resin.

Also, the amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms to be blended is preferably 0.05 to 0.09 mol per 1 kg of the polystyrene resin. When the amount of the hydrofluoroolefin and the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms is within the above ranges, the extruded foam plate maintains heat insulation and lightness, and sparks scattered by welding or the like come into contact. It is possible to further improve the flame retardancy under more severe conditions as assumed. From the above viewpoint, it is more preferable that the amount of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms is 0.07 to 0.09 mol per 1 kg of the polystyrene resin.

Further, the total amount of the above-mentioned physical foaming agents to be compounded in the present invention is preferably 0.8 to 2.0 mol per 1 kg of polystyrene resin. When the total amount of the physical foaming agent is within the above range, the apparent density of the entire extruded foam board can be further reduced, and the extruded foam board can have excellent appearance (surface properties). From the above point of view, the total amount of the physical foaming agent compounded is more preferably 0.9 to 1.8 mol, more preferably 1.0 to 1.5 mol, per 1 kg of polystyrene resin.

(Flame retardants)
A flame retardant can be added to the extruded polystyrene resin foam board of the present invention. The flame retardant is not particularly limited as long as it is a flame retardant that can be usually blended in a polystyrene resin extruded foam board. Examples include brominated butadiene-styrene copolymer, tetrabromobisphenol-A-bis ( 2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-S-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis(2,3-dibromo-2- methyl propyl 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 typified by -tribromobutyl) isocyanurate, in addition to brominated isocyanurates represented by tris (2,3,4-tribromobutyl) isocyanurate, tris (2,3-dibromopropyl) cyanurate, cresyl di-2,6- Nitrogen-containing cyclic compounds such as xylenyl phosphate, antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, pentabromotoluene, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, melamine, melam, and melem , silicone compounds, inorganic compounds such as boron oxide, zinc borate, and zinc sulfide, phosphoric acid esters represented by triphenyl phosphate, red phosphorus, ammonium polyphosphate, phosphazene, and phosphorus compounds such as hypophosphite. compounds and the like. These compounds can be used alone or in combination of two or more.

When blending the above flame retardant, the blending amount is preferably 5 parts by mass or less (including 0 parts) with respect to 100 parts by mass of the polystyrene resin. By setting the amount of the flame retardant added within the above range, an extruded foam board having excellent flame retardancy can be obtained without the flame retardant inhibiting foamability. From the above point of view, the amount of the flame retardant compounded is preferably 0.5 to 4 parts by mass, more preferably 1 to 3.5 parts by mass based on 100 parts by mass of the polystyrene resin.

(Additive)
In addition to the polystyrene resin, physical foaming agent and flame retardant described above, the extruded polystyrene resin foam board of the present invention may contain other additives as long as they do not interfere with the objects and effects of the present invention. These include, for example, cell control agents, heat stabilizers, flame retardant aids, colorants, antioxidants, radiation inhibitors, fillers, lubricants, and the like.

Inorganic substances such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, clay, aluminum oxide, bentonite, and diatomaceous earth are exemplified as cell regulators. Two or more kinds of the cell control agent can be used in combination. The amount of the foam control agent compounded is preferably 1 to 7.5 parts by mass or less, more preferably 3 to 7 parts by mass, based on 100 parts by mass of the polystyrene resin.

The heat stabilizer includes one or more heat stabilizers selected from epoxy compounds, phenol compounds, hindered amine compounds, and phosphite compounds.

The flame retardant aid includes at least one flame retardant aid selected from diphenylalkanes, diphenylalkenes and polyalkylbenzenes. By blending these, it is possible to improve the oxygen index (minimum concentration of oxygen required to keep the material burning) of the resulting foam board.

Diphenylalkanes include, for example, 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3, 4-diethyl-3,4-diphenylhexane can be mentioned. Diphenylalkenes include, for example, 2,4-diphenyl-4-methyl-1-pentene and 2,4-diphenyl-4-ethyl-1-pentene. Polyalkylenebenzenes include, for example, poly-1,4-diisopropylbenzene (CCPIB). Among these, poly-1,4-diisopropylbenzene (CCPIB) is preferred.

Examples of the radiation suppressing agent include fine powders having a radiation suppressing effect, and examples thereof include metal oxides such as titanium oxide, metals such as aluminum, carbon black, carbon such as graphite, and ceramics. can. These can be used singly or in combination of two or more.

(Manufacturing method of polystyrene resin foam board)
An embodiment of the method for producing a polystyrene resin foam board of the present invention will be described below. The method for producing a polystyrene resin foam board of the present invention comprises a step of extruding and foaming an expandable molten resin composition obtained by kneading a polystyrene resin, a physical foaming agent, a flame retardant and other additives to form a plate. A method involving

Specifically, a polystyrene resin and, if necessary, additives such as a flame retardant, a cell control agent, a heat stabilizer, and a flame retardant aid are supplied to an extruder, heated and kneaded, and then a physical foaming agent is added. is injected into an extruder and kneaded, for example, the foamable polystyrene resin melt composition obtained by kneading is extruded into a low pressure region (usually in the atmosphere) from a high pressure extruder through a flat die to foam. Mold placed at the exit of the die (shaping device (guider) consisting of two upper and lower plates made of polytetrafluoroethylene resin, etc., installed in parallel or so as to gradually expand from the entrance to the exit) A method of manufacturing a polystyrene-based resin extruded foam plate (hereinafter sometimes referred to as a base plate) by passing it through a forming tool such as a forming roll or the like to form a plate can be adopted. Further, the width, length and thickness can be adjusted by cutting the extruded foam plate (original plate) obtained by this method, and a plate-shaped polystyrene resin extruded foam plate of a desired size can be obtained. .

The physical properties of the extruded polystyrene resin foam board of the present invention are described below.

(apparent density)
The polystyrene resin foam board of the present invention has a ratio of the apparent density (I) of the surface layer portion up to 5 mm in the thickness direction from the surface of the extruded foam board to the apparent density (II) of the entire extruded foam board ((I) / ( II)) is greater than 1.10. That the apparent density ratio ((I)/(II)) is within the above range means that a high-density layer having a high apparent density is formed on the surface layer of the extruded foam board. Therefore, in the foamed plate of the present invention, the amount of butane in the foamed plate is small and the ratio of the apparent densities ((I)/(II)) is within the above range. It is believed that the material will have a high degree of flame retardancy even under severer conditions such as those assumed to come into contact with sparks. In addition, the extruded foam board is excellent in mechanical strength.
From the above viewpoint, the ratio ((I)/(II)) of the apparent density (I) of the surface layer portion to the apparent density (II) of the entire extruded foam board is preferably more than 1.15, and more than 1.20. is more preferred, and more than 1.25 is even more preferred. The upper limit of the apparent density ratio ((I)/(II)) is approximately 1.5.

The polystyrene-based resin extruded foam board of the present invention uses a physical foaming agent containing a specific amount of aliphatic saturated hydrocarbon having 3 to 5 carbon atoms in addition to hydrofluoroolefin and other physical foaming agents as physical foaming agents. Therefore, the ratio ((I)/(II)) of the apparent density (II) of the whole to the apparent density (I) of the surface layer satisfies the above range. Although the reason for this is not clear, it is believed that the foaming rate of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms is faster than that of hydrofluoroolefins.
On the other hand, the extruded foam board produced using a physical foaming agent containing hydrofluoroolefin and other physical foaming agents and not containing aliphatic saturated hydrocarbons having 3 to 5 carbon atoms has the above ratio ((I)/( II)) is less than 1.10, a high-density layer with a high apparent density is not formed on the surface layer of the extruded foam board, and under more severe conditions assuming contact with sparks scattered by welding etc. Flame retardancy may be insufficient.

The apparent density (I) of the surface layer portion of the extruded foam board can be determined as follows. First, a test piece is cut out from a portion up to 5 mm in thickness direction from the surface of the extruded foam board, and the weight and outer dimensions of the test piece can be obtained. In this specification, the surface refers to the outermost surface of a polystyrene-based resin extruded foam board (original board). When the outermost surface of the extruded polystyrene resin foam plate (original plate) is cut to adjust the thickness, the term refers to the outermost surface of the extruded foam plate after cutting.

The apparent density (II) of the entire extruded polystyrene resin foam board is preferably 20 to 50 kg/m ³ , more preferably 25 to 45 kg/m ³ , further preferably 30 to 40 kg/m ³ . preferable.

The overall apparent density of the extruded foamed board is obtained by dividing the weight of the polystyrene resin foamed board by the volume determined from the external dimensions of the foamed board, based on JIS K7222 (2005), and converting the value into units (kg/m ³ ). Desired.

(thickness and width)
The thickness of the extruded polystyrene resin foam plate (original plate) is preferably 35 mm or more, more preferably 40 mm or more, and even more preferably 50 mm or more, from the viewpoint of heat insulation. The upper limit of the thickness of the extruded foam board is approximately 120 mm.
From the same point of view, the width of the extruded polystyrene resin foam plate (original plate) is preferably 600 mm or more, more preferably 800 mm or more.

(Average bubble diameter)
The polystyrene resin extruded foam plate of the present invention has an average cell diameter of 60 to 100 μm in the thickness direction of the surface layer portion from the surface of the extruded foam plate to 2 mm in the thickness direction, and the thickness of the central part in the thickness direction of the extruded foam plate. It is preferred that the average cell diameter in the direction exceeds 100 μm. When the average cell diameter in the thickness direction of the extruded foamed board is within the above range, the foamed board is more excellent in heat insulation, moldability, and the like. In particular, it is considered that a layer having a high apparent density is likely to be formed in the surface layer portion due to the small average cell diameter in the thickness direction of the surface layer portion up to 2 mm in the thickness direction from the surface of the extruded foam board. Therefore, the flame retardance is improved under severer conditions, such as when sparks scattered by welding or the like come into contact. In the present invention, the average cell diameter in the thickness direction of the surface layer portion up to 2 mm in the thickness direction from the surface of the extruded foam plate is smaller than the average cell diameter in the thickness direction of the central portion in the thickness direction of the extruded foam plate, and the value is 60 to 60. The reason why it is within the range of 100 μm is considered to be the use of aliphatic saturated hydrocarbons having 3 to 5 carbon atoms, which are foaming agents having a faster foaming rate than hydrofluoroolefins.
From the above point of view, the average cell diameter in the thickness direction of the surface layer portion up to 2 mm in the thickness direction from the surface of the extruded foam plate is more preferably 70 to 90 μm, and even more preferably 75 to 88 μm. The average cell diameter in the thickness direction of the central portion in the thickness direction of the extruded foam board is more preferably more than 150 μm, and more preferably more than 200 μm. The upper limit of the average cell diameter in the thickness direction of the central portion in the thickness direction of the extruded foam board is approximately 350 μm.

The average cell diameter in the thickness direction of the surface layer portion up to 2 mm in the thickness direction from the surface of the extruded foam plate means the cell diameter in the thickness direction obtained by the following measuring method. First, cut out a portion up to 2 mm in the thickness direction from the surface of the foam plate to make a test piece, and the individual cells present in the vertical cross-sectional area cross section in the extrusion direction of the test piece (vertical cross section perpendicular to the extrusion direction of the foam plate) On the other hand, draw two straight lines perpendicular to the thickness direction and circumscribe the bubble, and measure the distance between the straight lines. This is performed for each bubble, and the obtained values are arithmetically averaged to obtain the bubble diameter in the thickness direction. This foam board was divided into 10 equal parts in the width direction, and 10 test pieces cut out from the vicinity of the center part were measured, and the arithmetic average value was calculated from the surface of the extruded foam board to the surface layer part up to 2 mm in the thickness direction. is the average bubble diameter of

The average cell diameter at the central portion in the thickness direction of the extruded foam plate means the cell diameter obtained by the following measuring method. First, a portion up to 2.5 mm in each surface direction (total thickness 5 mm) is cut out from a straight line that bisects the foam plate in the thickness direction to obtain a test piece, and the vertical cross-sectional area cross section of the test piece in the extrusion direction (of the foam plate Two straight lines perpendicular to the thickness direction and circumscribing each bubble are drawn, and the distance between the straight lines is measured. This is performed for each bubble, and the obtained values are arithmetically averaged to obtain the bubble diameter in the thickness direction. The foam board is divided into 10 equal parts in the width direction, and 10 test pieces cut out from the vicinity of the central part thereof are measured. .

(Closed cell rate)
The closed cell ratio of the polystyrene resin foam board in the present invention is preferably 60% or more, more preferably 80% or more, and still more preferably 90% or more from the viewpoint of obtaining excellent physical properties such as heat insulation and mechanical strength. .

In addition, the closed cell ratio: S (%) is measured according to the procedure C described in ASTM D2856-70 (1976 recertification) using an air comparison type hydrometer 930 manufactured by Toshiba Beckman Co., Ltd. The actual volume of the test piece to be measured (the sum of the volume of the closed cells and the volume of the resin portion): Vx (cm ³ ) can be calculated by the following formula (1).
S (%) = (Vx-W/ρ) x 100/(Va-W/ρ) (1)
However, Va, W, and ρ in the above formula are as follows.
Va: Apparent volume of test piece used for measurement (cm ³ )
W: Mass of test piece (g)
ρ: Density of the resin composition constituting the test piece (g/cm ³ )

The density ρ (g/cm ³ ) of the resin composition was determined by the mass W (g) of the test piece and the test piece used for the measurement by defoaming air bubbles with a hot press and then cooling the sample obtained. can be obtained from the volume (cm ³ ) of

(Thermal conductivity)
The thermal conductivity of the polystyrene resin foam board in the present invention is preferably 0.020 to 0.040 W/m·K, more preferably 0.021 to 0.026 W/m·K. When the thermal conductivity of the foam board is within the above range, excellent heat insulation can be obtained. The thermal conductivity is measured according to the flat plate heat flow meter method (2 heat flow meters method, high temperature side 38 ° C., low temperature side 8 ° C., average temperature 23 ° C.) described in JIS A1412-2 (1999). can do.

(oxygen index)
The polystyrene resin foam board of the present invention exhibits an excellent oxygen index. The oxygen index can be measured according to JIS K7201-2 (2007).

(Combustibility test (spark))
The extruded polystyrene resin foam plate of the present invention exhibits better flame retardancy under severer conditions, such as when sparks scattered by welding or the like come into contact. A combustion test under such conditions can be performed, for example, using fireworks as a source of fire. Specifically, a firework is placed so that the tip of the firework is at a distance of 20 mm from the surface of the extruded foam board, the firework is ignited, and 30 seconds after the spark is applied to the surface of the foam board, the surface of the foam board It can be done by observing and confirming the presence or absence of ignition.

EXAMPLES The method for producing a polystyrene-based resin foam board of the present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples.

[Device]
A first extruder with an inner diameter of 180 mm and a second extruder with an inner diameter of 225 mm are connected in series, and a flat die with a resin outlet (die lip) having a rectangular cross section in the width direction with a gap of 2.5 mm × width of 400 mm. A shaping device connected to the outlet of the second extruder and composed of a pair of upper and lower polytetrafluoroethylene resin plates installed parallel to the resin outlet of the flat die (interval: 55 mm). was used.

In addition, the following materials were used as materials to be introduced into the manufacturing apparatus.
[Resin component]
(polystyrene resin)
Polystyrene: HP-600ANJ (manufactured by DIC)
(Copolymer)
SPET: ALTESTER30 (manufactured by Mitsubishi Gas Chemical Company)

[Flame retardants]
Flame retardant 1: Tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropyl ether), Daiichi Kogyo Seiyaku, trade name "Pyrogard SR130"
Flame retardant 2: Tetrabromobisphenol-A-bis(2,3-dibromopropyl ether), Daiichi Kogyo Seiyaku, trade name "Pyrogard SR720"
A mixture of flame retardant 1 and flame retardant 2 at a weight ratio of 60:40 was used as a flame retardant.

[Physical blowing agent]
Saturated hydrocarbon: isobutane (i-Bu)
Hydrofluoroolefin: 1-chloro-3,3,3-trifluoropropene (manufactured by Honeywell, product name “Solstice 1233zd (E)”)
trans-1,3,3,3-tetrafluoropropene (transHFO-1234ze)
Other blowing agents: dimethyl ether (DME), ethanol (EtOH), water, carbon dioxide, chloromethane (MeCl)

[Additive]
Air bubble control agent: talc (manufactured by Matsumura Sangyo, product name “High Filler #12”)
Coloring agent: Gray MB (PSX-ET4217B manufactured by Nikko Bix Co., Ltd.)

(manufacturing conditions)
A polystyrene resin, a flame retardant, and each additive are supplied to the first extruder of the above equipment so that the blends and blending amounts shown in Tables 1 and 2 are obtained, heated to 200 ° C. and kneaded, and the foaming agent is injected. A physical foaming agent having the composition and amount shown in Table 1 was supplied from the inlet to the melt and further kneaded. Then, the foamable resin melt is sequentially supplied to the second extruder, and the extruded resin temperature is set to a foamable resin temperature suitable for foaming (113 ° C: foamability measured at the position of the joint between the extruder and the die temperature of resin melt), extruded from the die lip into the guider at a discharge rate of 700 kg/hr at the die pressure shown in Tables 1 and 2, passed through the guider and molded (shaped) into a plate shape with a width of 1050 mm. A polystyrene-based resin extruded foam plate (original plate) having a thickness of 55 mm was obtained. Furthermore, immediately after production, the original plate was adjusted to a width of 910 mm and a thickness of 50 mm by cutting to obtain polystyrene resin foam plates of Examples 1 to 11 and Comparative Examples 1 to 7. In addition, in adjusting the thickness of the foam board, about 2 mm was cut from both surfaces of the foam board. After that, the cut foam board was moved into a constant temperature and humidity room at 23° C. and a relative humidity of 50%, and left still in the constant temperature and humidity room.

Regarding the obtained polystyrene resin foam boards of Examples 1 to 11 and Comparative Examples 1 to 7, the physical properties of the surface layer (average cell diameter, apparent density), the physical properties of the entire foam board (average cell diameter, apparent density), closed cells The rate, foaming state, density ratio, thermal conductivity, combustibility test (flame), oxygen index, and combustion test (spark) were measured by the following methods and evaluated according to the following criteria. The results are shown in Tables 1 and 2. For the measurement and evaluation of the extruded foam plate described below, a 2 mm portion cut from the surface of the foam plate (original plate) passed through the guider and formed into a plate-like shape was used.

(Surface layer physical properties)
[Average bubble diameter in the thickness direction]
It was obtained according to the method described above. First, a portion up to 2 mm in the thickness direction is cut out from the surface of the foam plate to obtain a test piece (5 mm width x 2 mm thickness), and the vertical cross-sectional area cross section of the test piece in the extrusion direction (vertical cross section perpendicular to the extrusion direction of the foam plate). Two straight lines perpendicular to the thickness direction and circumscribing each bubble were drawn, and the distance between the straight lines was measured. This was performed for each bubble, and the obtained values were arithmetically averaged to determine the bubble diameter in the thickness direction. The above measurement is performed by dividing the foam board into 10 equal parts in the width direction, measuring 10 test pieces cut out from the vicinity of the center part, and calculating the arithmetic mean value from the surface of the extruded foam board to 2 mm in the thickness direction. It was taken as the average bubble diameter of the surface layer portion.
[Apparent density]
A test piece (width 50 mm×length 50 mm×thickness 5 mm) cut out from the surface of the extruded foam board in a thickness direction of 5 mm was obtained from the weight and outer dimensions of the test piece, and the apparent density was calculated and arithmetically averaged. For the above measurements, the foam board was divided into 10 equal parts in the width direction, and 10 test pieces cut out from the vicinity of the central part were measured, and the arithmetic average value was taken as the apparent density of the surface layer.

(Entire foam board physical properties)
[Average bubble diameter in the thickness direction]
It was obtained according to the method described above. First, from a straight line that bisects the foam board in the thickness direction, a portion up to 2.5 mm in each surface direction (total thickness 5 mm) is cut out to make a test piece (width 5 mm × thickness 5 mm), and the extrusion direction of the test piece is perpendicular. Cross-sectional area Cross-section (vertical cross-section perpendicular to the extrusion direction of the foam board) For each bubble that exists, draw two straight lines that are perpendicular to the thickness direction and circumscribe the bubbles, and measure the distance between the straight lines do. This was performed for each bubble, and the obtained values were arithmetically averaged to determine the bubble diameter in the thickness direction. The above measurement is performed by dividing the foam board into 10 equal parts in the width direction, measuring 10 test pieces cut out from the vicinity of the center part, and calculating the arithmetic mean value of the average cell diameter at the center part in the thickness direction of the extruded foam board. and
[Apparent density]
It was obtained by dividing the weight of the extruded foam board by the volume determined from the outer dimensions of the foam board and converting the value into units (kg/m ³ ).

(Closed cell rate)
Three test pieces (width 25 mm×length 25 mm×thickness 40 mm) were cut out from the vicinity of the central portion in the width direction of the extruded foam board, and the independent cell ratio was measured by the above method and arithmetically averaged.

(Foam state)
The foaming state of the extruded foam board was evaluated according to the following criteria.
○: No cracks, spots, etc. ×: Poor appearance, cracks, spots, etc.

(Apparent density ratio)
The apparent density (I) of the surface layer portion was divided by the apparent density (II) of the entire extruded foam board to calculate the apparent density ratio ((I)/(II)).

(Thermal conductivity)
Three samples of width 200 mm × length 200 mm × thickness 50 mm were cut out from the central part of the extruded foam board in the width direction, and the plate heat flow meter method described in JIS A1412-2 (1999) (two heat flow meters method, high temperature side 33 °C, low temperature side 13 °C, average temperature 23 °C), and the arithmetic average was taken.

(Combustion test (flame))
A flame-contact combustion test was conducted under the following conditions in accordance with JIS A9511 (2009).
Five test pieces each having a width of 25 mm, a length of 200 mm, and a thickness of 10 mm were cut out from the central portion of the extruded foam plate in the width direction, and the test pieces were marked with an ignition limit indicator line and a combustion limit indicator line. When the candle for the fire source has a thickness of about 20 mm and a wick length of 10 mm, the flame length is 50 mm or more and the thickness is about 7 mm or more.
The candle was moved to the ignition limit indicator line at a constant speed over about 5 seconds, and after reaching the indicator line, the flame was retracted. The time from that moment until the flame extinguished was measured, the presence or absence of residual dust, and the position at which combustion stopped was confirmed, and evaluated according to the following criteria.
1. 2. The average extinguishing time of 5 test pieces is 3 seconds or less. No residue 3. Those satisfying the above 1 to 3 not exceeding the flammability limit indicator line were evaluated as acceptable, and those not satisfying any of the above 1 to 3 were disqualified as x.

(oxygen index)
The oxygen index was measured according to the combustion test method for polymeric materials by the oxygen index method described in JIS K7201-2 (2007). Five test pieces of width 10 x length 150 x thickness 10 mm were cut out from the central part of the extruded foam board in the width direction, and after preconditioning in an atmosphere of 60 degrees Celsius for 4 weeks, the temperature was 23 degrees Celsius and the relative humidity was 50. % adjusted for 168 hours was used. A flame retardancy tester (ON-1D model manufactured by Suga Test Instruments Co., Ltd.) was used as a measuring instrument. The values obtained for the three specimens were arithmetically averaged.

(Combustibility test (spark))
Five test pieces each having a width of 150 mm, a length of 150 mm, and a thickness of 50 mm were cut out from the central portion in the width direction of the extruded foam board.
As a test device, set a firework so that the tip of the firework is at a distance of 20 mm from the test piece surface, ignite the firework, hit the surface of the test piece with the spark, and after 30 seconds, check the state of the surface of the test piece. Evaluation was made according to the following criteria.
When the surface of the test piece burned for 3 seconds or longer due to the spark, it was determined that the test piece was ignited and was judged to be unacceptable. In addition, when the surface melted but did not ignite, it was judged to be acceptable, and when all five test pieces were acceptable, it was indicated by ◯.

In the combustibility test (spark), NEW Gold Sparkler manufactured by Inoue Toy Fireworks Co., Ltd. was used as the fireworks. The spark temperature is approximately 1200 to 1500°C.

From the results shown in Table 1, the physical foaming agent having the hydrofluoroolefin, the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, and other foaming agent in the blending amount and blending ratio specified by the present invention was used. The foam boards of Examples 1-11 had a high oxygen index and did not burn even when directly contacted by a spark. Moreover, the foamed plate of the present invention had a high level of flame retardancy even when the amount of the flame retardant compounded was small or even when the amount was not compounded.

On the other hand, from the results shown in Table 2, the foamed boards of Comparative Examples 1 to 5, in which the amount of butane added to the total amount of the physical blowing agent exceeds 10 mol%, had a high-density layer on the surface layer. The content of butane in the foam board was large, and the flame retardancy against sparks was insufficient.

Further, from the results shown in Table 2, it was confirmed that Comparative Examples 6 and 7, in which isobutane, which is a combustible gas, was not blended were inferior to the examples in which isobutane was blended in flame retardancy against sparks. It is considered that this is because the ratio of the apparent density of the surface layer to the apparent density of the entire foam board is smaller than the value specified in the present invention.

From these results, according to the polystyrene resin extruded foam board of the present invention, on the premise that it contains a specific aliphatic saturated hydrocarbon, a hydrofluoroolefin, and another foaming agent as a physical foaming agent, The extruded polystyrene resin foam board, in which the ratio of the blending amount of hydrogen and hydrofluoroolefin is set to a specific amount, and the apparent density of the surface layer portion is specified with respect to the apparent density of the entire polystyrene resin foam board, is excellent in heat insulation and light weight. , was confirmed to have a high degree of flame retardancy.

Claims (6)

A polystyrene-based resin extruded foam board obtained by extruding and foaming a polystyrene-based resin using a physical foaming agent,
The physical blowing agent contains an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, a hydrofluoroolefin and another blowing agent,
The total amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms and the hydrofluoroolefin is 0.30 to 1.10 mol per 1 kg of the polystyrene resin,
The ratio of the blended amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms to the total 100 mol% of the blended amount of the physical blowing agent is 0.5 mol% or more and less than 10 mol%,
The amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms is 0.09 mol or less per 1 kg of the polystyrene resin,
The average cell diameter in the thickness direction of the surface layer portion up to 2 mm in the thickness direction from the surface of the extruded foam plate is 60 to 100 μm, and the average cell diameter in the thickness direction of the central portion in the thickness direction of the extruded foam plate exceeds 150 μm. ,
The ratio ((I)/(II)) of the apparent density (I) of the surface layer portion up to 5 mm in the thickness direction from the surface of the extruded foam board to the apparent density (II) of the entire extruded foam board exceeds 1.10. A polystyrene-based resin extruded foam board characterized by: 2. The extruded polystyrene resin foam board according to claim 1, wherein the other foaming agent includes one or more physical foaming agents selected from dimethyl ether, ethanol, carbon dioxide and water. The molar ratio of the compounding amount (A) of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms with respect to 1 kg of the polystyrene resin and the compounding amount (B) of the hydrofluoroolefin with respect to 1 kg of the polystyrene resin ((A)/(B) ) is 0.5 or less, the extruded polystyrene resin foam board according to claim 1 or 2. The polystyrene-based according to any one of claims 1 to 3, wherein the amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms is 0.05 mol or more per 1 kg of the polystyrene-based resin. Resin extruded foam board. 5. The extruded polystyrene resin foam board according to any one of claims 1 to 4, wherein the hydrofluoroolefin is 1-chloro-3,3,3-trifluoropropene. The extruded polystyrene resin foam board according to any one of claims 1 to 5, characterized in that the apparent density (II) of the entire extruded foam board is 20-45 kg/m ³ .