JP2020125375A - Polystyrene-based resin extrusion foam plate - Google Patents

Abstract

To provide a polystyrene-based resin extrusion foam plate having high flame retardancy against a severer condition, in particular, contact of spark.SOLUTION: A polystyrene-based resin extrusion foam plate is obtained by extrusion-foaming a polystyrene-based resin using a physical foaming agent, in which the physical foaming agent contains aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, hydrofluoroolefin and other foaming agents, the total blended amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms and the hydrofluoroolefin is 0.30-1.10 mol with respect to 1 kg of the polystyrene-based resin, a ratio of the blended amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms with respect to 100 mol% of the total of the blended amount of the physical foaming agent is 0.5 mol% or more and less than 10 mol%, and a ratio ((I)/(II)) of the bulk density (I) of the surface layer portion to 5 mm in a thickness direction from the surface of the extrusion foam plate of the surface portion to the bulk density (II) of the whole extrusion foam plate exceeds 1.10.SELECTED DRAWING: None

Description

The present invention relates to a polystyrene resin extruded foam plate.

The polystyrene-based resin extruded foam plate used for applications such as building materials is required to have high flame retardancy that satisfies the flammability standard of the extruded polystyrene foam heat insulating plate defined by, for example, JIS A9511 (2009).

As a method for imparting flame retardancy to a polystyrene resin extruded foam plate, for example, a method in which a flame retardant is blended and a nonflammable gas is used as a physical foaming agent is disclosed (see Patent Document 1). Further, an extruded foam plate containing a flame retardant, a non-combustible gas as a physical foaming agent, an organic foaming agent having a high PS permeability, and a foaming agent containing no organic foaming agent having a low PS permeability. Is disclosed (see Patent Document 2).

JP, 2008-100352, A Japanese Patent No. 5892300

In recent years, the required level of flame retardancy for extruded polystyrene resin foam plates has been increasing, and there is a demand for extruded polystyrene resin foam plates exhibiting higher flame retardancy. Specifically, for example, even if sparks scattered by welding or the like come into contact with the foam plate at a construction site, there is a demand for a high degree of flame retardancy that does not cause ignition.

The polystyrene-based resin extruded foam plate described in Patent Document 1 has a relatively large amount of butane, which is a flammable gas, in the foam plate, so more severe conditions such as the contact of sparks scattered by welding or the like. There was a risk that the flame retardancy would be insufficient.

The polystyrene resin extruded foam plate described in Patent Document 2 has higher flame retardancy because it does not contain butane, which is a flammable gas, in the foam plate. However, the foamed plate described in Patent Document 2 is not intended to have flame retardancy under more severe conditions such as sparks scattered by welding or the like, and the flame retardance is insufficient under such conditions. There was a risk that

The present invention has been made in view of such a background, and an object of the present invention is to provide a polystyrene resin extruded foam plate having high flame retardancy against more severe conditions, particularly against contact with sparks.

The present invention provides the polystyrene resin extruded foam plate described below.
<1> A polystyrene resin extruded foam plate 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,
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,
The ratio of the blending 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 100 mol% in total of the blending amount of the physical foaming agent,
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 plate and the apparent density (II) of the entire extruded foam plate exceeds 1.10. A polystyrene resin extruded foam plate characterized by:
<2> The polystyrene resin extruded foam plate 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> Molar ratio of the compounding amount (A) of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms to 1 kg of the polystyrene resin and the compounding amount (B) of hydrofluoroolefin to 1 kg of the polystyrene resin ((A)/ (B)) is 0.5 or less, the polystyrene-based resin extruded foam plate 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 with respect to 1 kg of the polystyrene resin. The polystyrene-based resin extruded foam plate according to [4].
<5> The polystyrene resin extruded foam plate 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 from the surface of the extruded foam plate to 2 mm in the thickness direction 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 polystyrene-based resin extruded foam plate according to any one of <1> to <5>, which has a diameter of more than 100 μm.
<7> The polystyrene resin extruded foam plate according to any one of <1> to <6>, wherein an apparent density (II) of the entire extruded foam plate is 20 to 50 kg/m ³ .

The polystyrene resin extruded foam plate of the present invention contains an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms as a physical foaming agent, hydrofluoroolefin, and another foaming agent, and has 3 carbon atoms with respect to the total blending amount of the physical foaming agent. By setting the blending amount of the aliphatic saturated hydrocarbon of 5 to a specific ratio and setting the apparent density of the surface layer portion with respect to the apparent density of the entire polystyrene-based resin extruded foam plate to a specific range, excellent heat insulation and lightweight properties are obtained. It is possible to obtain a polystyrene resin extruded foam plate having a high degree of flame retardancy.

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

(Polystyrene resin)
The polystyrene resin in the present invention is a polymer mainly composed of styrene, and a styrene homopolymer or a copolymer of styrene and a vinyl monomer copolymerizable with 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. Further, these polystyrene-based resins may be used as a mixture of two or more kinds. The polystyrene resin may contain a polyfunctional monomer unit component such as divinylbenzene or a hyperbranched macromonomer. Among these polystyrene-based resins, polystyrene is preferable from the viewpoint of foamability.

The polystyrene resin has a styrene component of 50 mol% or more, preferably 60 mol% or more, more preferably 80 mol% or more, and further preferably 90 mol% or more.

The polystyrene resin may contain other polymers within the range in which the objects and effects of the present invention are achieved. As the other polymer, polyethylene resin (one kind or a mixture of two or more kinds selected from the group of ethylene homopolymer and ethylene copolymer having an ethylene unit content of 50 mol% or more), polypropylene -Based resin (one kind or a mixture of two or more kinds selected from the group of propylene homopolymer and propylene-based copolymer having a propylene unit component content of 50 mol% or more), polyphenylene ether-based resin, polymethyl methacrylate Thermoplastic resin such as styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer hydrogenated product, styrene-isoprene-styrene block copolymer water Examples thereof include additives and thermoplastic elastomers such as styrene-ethylene copolymers. These other polymers can be mixed according to the purpose so as to be less than 50% by mass, preferably 30% by mass or less in the polystyrene resin.

Further, in order to enhance the heat insulating property of the foam plate, a material containing an amorphous or low crystalline polyethylene terephthalate 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 copolymer is less than 5 J/g (including 0) and less than 2 J/g (including 0) from the viewpoint of the production stability of the extruded foam plate. Is preferable, and more preferably less than 1 J/g (including 0). The amount of heat of fusion is "when measuring the heat of fusion after performing a constant heat treatment" described in JIS K7122 (2012) (both the heating rate and the cooling rate in the condition adjustment of the test piece are 10°C/ The measurement is performed based on a DSC curve obtained by using a heat flux differential scanning calorimeter (hereinafter referred to as a DSC device).

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 700 to 1500 Pa·s. It is more preferable that there is. The melt viscosity is a value measured under the conditions of a temperature of 200°C and a shear rate of 100 sec- ¹ based on JIS K7199:1999.

(Physical foaming agent)
The physical foaming agent in the present invention contains an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, a hydrofluoroolefin, and another foaming agent.

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

[Hydrofluoroolefin]
The present invention uses hydrofluoroolefin (HFO) as a physical blowing agent. HFO includes a hydrofluoroolefin having 3 to 5 carbon atoms, specifically, trans-1,3,3,3-tetrafluoropropene (trans HFO-1234ze), cis-1,3,3,3-tetra. Fluoropropene (cis HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1-chloro-3,3,3-trifluoropropene (HFO-1233zd) and the like can be mentioned. .. These hydrofluoroolefins are foaming agents that have low thermal conductivity in a gaseous state, are difficult to burn, have a low ozone depletion potential, and have a very low global warming potential (GWP). Among the above hydrofluoroolefins, trans-1,3,3,3-tetrafluoropropene (transHFO-1234ze), 1-chloro-3,3,3 has low thermal conductivity and good handleability. It is preferable to use 3-trifluoropropene (HFO-1233zd), and it is more preferable to use 1-chloro-3,3,3-trifluoropropene (HFO-1233zd). Further, these hydrofluoroolefins can be used alone or in combination of two or more kinds.

[Other foaming 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, but has a polystyrene transmittance of 0.5×10 ⁻¹⁰ cc·cm/cm ² ·s·cmHg or more. Are preferred physical blowing agents. Other physical foaming agents having a polystyrene transmittance within the above range are preferable because they dissipate early from the polystyrene resin and do not affect the flame retardancy and heat insulation of the polystyrene resin extruded foam plate. Examples of the other foaming agent having a polystyrene transmittance within the above range include dimethyl ether, ethanol, carbon dioxide, water, methyl chloride, ethyl chloride and the like. Among them, it is preferable to include one or more physical foaming agents selected from dimethyl ether, ethanol, carbon dioxide, and water from the viewpoints of environmental properties, 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 obtained polystyrene-based resin extruded foam plate has a better moldability and a good appearance.

The polystyrene-based resin extruded foam plate 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. by setting the blending amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms to the blending amount to a specific ratio and setting the apparent density of the surface layer portion to the apparent density of the entire polystyrene-based resin extruded foam plate to a specific range It has excellent flame retardancy even under severer conditions, such as when it is assumed that sparks scattered by will contact.

Conventionally, when imparting flame retardancy to a polystyrene-based resin extruded foam plate, it has been considered to manufacture it using a nonflammable foaming agent such as hydrofluoroolefin together with a combustible foaming agent such as butane as a physical foaming agent. Came. However, the above-mentioned conventional polystyrene-based resin extruded foam plate has not been manufactured assuming flame retardancy under more severe conditions such as the contact of sparks scattered by welding or the like.

In the examples described later, even when produced using a non-combustible gas hydrofluoroolefin as a physical foaming agent, if the blending ratio of butane in the physical foaming agent is high, the resulting foamed plate will be Although it satisfies the flammability standard stipulated in JIS A9511 (2006), it does not have sufficient flame retardancy under more severe conditions such as when sparks scattered by welding are supposed to come into contact. there were.

Furthermore, even in a polystyrene resin extruded foam plate manufactured using a foaming agent that does not contain butane, which is a flammable gas, as a physical foaming agent, it is assumed that sparks scattered by welding etc. will come into contact with more severe conditions. However, the flame retardancy was insufficient.

On the other hand, the inventors of the present invention include an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, a hydrofluoroolefin, and another physical foaming agent, and having 3 to 5 carbon atoms relative to the total blending amount of the physical foaming agent. The polystyrene resin extruded foam plate manufactured using a physical foaming agent with a specified amount of the group saturated hydrocarbon content satisfies the flammability standard stipulated in JIS A9511 (2006) and is scattered by welding etc. It has been found that even in more severe conditions such as when it is assumed that the sparks come into contact with each other, the flame retardancy is high.

The reason why the polystyrene-based resin foam plate obtained by the present invention has a high degree of flame retardance even under more severe conditions, such as assuming that sparks scattered by welding etc. come into contact, is that butane remains in the foam plate. It is considered that this is because the amount was small and a high-density layer having a high apparent density was formed on the surface layer of the extruded foam plate. As will be described later, in the extruded foam plate of the present invention, the 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 plate to the apparent density (II) of the entire extruded foam plate ((I )/(II)) exceeds 1.10. In the present invention, the addition of the hydrofluoroolefin and the other physical foaming agent, and the addition of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms makes the obtained extruded foam plate satisfy the above apparent density ratio. ..

In the physical foaming 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 foaming agent. .. When the proportion of the saturated saturated hydrocarbon having 3 to 5 carbon atoms is less than 0.5 mol%, a high-density layer having a high apparent density is not formed on the surface layer portion of the extruded foam plate and is scattered by welding or the like. There is a risk that flame retardancy will be insufficient under more severe conditions, such as when it is assumed that sparks will come into contact. Moreover, when the ratio of the blending amount of the C3-5 aliphatic saturated hydrocarbon exceeds 10 mol %, the residual amount of the C3-5 aliphatic saturated hydrocarbon in the extruded foam plate increases. , The flame retardancy against sparks may be insufficient.
From the above viewpoint, the lower limit of the proportion of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms is preferably 3 mol% or more, and preferably 5 mol% or more, based on 100 mol% of the total amount of the physical blowing agent. More preferably. Further, the upper limit of the proportion of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms is preferably 9 mol% or less, and is 8 mol% or less with respect to the total 100 mol% of the physical blowing agent. Is more preferable.

Moreover, the total compounding amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms and the hydrofluoroolefin is 0.30 to 1.10 mol with respect to 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 extruded foam plate obtained has excellent heat insulating properties, lightweight properties, flame retardancy, and the like. From the above viewpoint, the total blending amount is preferably 0.40 to 1.0 mol%, and more preferably 0.45 to 0.80 mol%.

In the present invention, the molar ratio ((A)/(A)/(A)/(A)/(A)) of the amount of aliphatic saturated hydrocarbon having 3 to 5 carbon atoms to 1 kg of polystyrene resin and (B) the amount of hydrofluoroolefin added to 1 kg of polystyrene resin. (B)) is preferably 0.5 or less. When the molar ratio ((A)/(B)) is within the above range, it is possible to further enhance the flame retardancy under more severe conditions such as the assumption that sparks scattered by welding or the like come into contact with each other. From the above viewpoint, the molar ratio is more preferably 0.4 or less, and further preferably 0.3 or less. The lower limit of the molar ratio is preferably 0.1.

In the present invention, the blending amount of hydrofluoroolefin 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 property and light weight of the extruded foam plate. From the above viewpoint, the blending amount of hydrofluoroolefin is more preferably 0.40 to 0.60 mol per 1 kg of polystyrene resin.

Further, the compounding amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms is preferably 0.05 to 0.09 mol per 1 kg of the polystyrene resin. When the blending amount of each of the hydrofluoroolefin and the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms is within the above range, the sparks scattered by welding or the like come into contact with the extruded foam plate while maintaining the heat insulating property and the lightweight property. It is possible to further enhance the flame retardancy under more severe conditions such as that assumed. From the above viewpoint, it is more preferable that the amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms be 0.07 to 0.09 mol with respect to 1 kg of the polystyrene resin.

Further, the total blending amount of the physical foaming agent in the present invention is preferably 0.8 to 2.0 mol with respect to 1 kg of the polystyrene resin. When the total blending amount of the physical foaming agent is within the above range, the apparent density of the entire extruded foam plate can be further lowered, and the extruded foam plate having excellent appearance (surface property) can be obtained. From the above viewpoint, the total blending amount of the physical foaming agent is more preferably 0.9 to 1.8 mol, and further preferably 1.0 to 1.5 mol per 1 kg of the polystyrene resin.

(Flame retardants)
A flame retardant can be added to the polystyrene resin extruded foam plate of the present invention. The flame retardant is not particularly limited as long as it is a flame retardant that can be usually compounded in a polystyrene resin extruded foam plate, and examples thereof 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), brominated bisphenol compounds, tris(2,3-dibromopropyl)isocyanurate, mono(2,3,4-tribromobutyl)isocyanurate, di(2,3,4) -Tribromobutyl) isocyanurate, brominated isocyanurate represented by tris(2,3,4-tribromobutyl)isocyanurate, tris(2,3-dibromopropyl)cyanurate, cresyldi-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, melem , Silicone compounds, inorganic compounds such as boron oxide, zinc borate and zinc sulfide, phosphoric acid ester compounds represented by triphenyl phosphate, red phosphorus compounds, ammonium polyphosphate, phosphazenes, phosphorus compounds such as hypophosphite A compound etc. are mentioned. These compounds can be used alone or in combination of two or more.

When the flame retardant is blended, the blending amount is preferably 5 parts by mass or less (including 0) with respect to 100 parts by mass of the polystyrene resin. By setting the addition amount of the flame retardant within the above range, an extruded foam plate having excellent flame retardancy can be obtained without the flame retardant hindering the foamability. From the above viewpoint, the blending amount of the flame retardant is preferably 0.5 to 4 parts by mass, and more preferably 1 to 3.5 parts by mass with respect to 100 parts by mass of the polystyrene resin.

(Additive)
In the polystyrene-based resin extruded foam plate of the present invention, in addition to the above-mentioned polystyrene-based resin, physical foaming agent and flame retardant, other additives can be blended within a range that does not impair the objects and effects of the present invention. Examples of these include a bubble regulator, a heat stabilizer, a flame retardant aid, a colorant, an antioxidant, a radiation suppressant, a filler, and a lubricant.

Examples of the cell regulator include inorganic substances such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, clay, aluminum oxide, bentonite and diatomaceous earth. Further, the cell regulator may be used in combination of two or more kinds. The blending amount of the cell regulator is preferably 1 to 7.5 parts by mass or less, and more preferably 3 to 7 parts by mass with respect to 100 parts by mass of the polystyrene resin.

Examples of the heat stabilizer include one or more heat stabilizers selected from epoxy compounds, phenol compounds, hindered amine compounds, and phosphite compounds.

Examples of the flame retardant aid include at least one flame retardant aid selected from diphenylalkane, diphenylalkene, and polyalkylbenzene. By blending these, the oxygen index (minimum concentration of oxygen required to maintain the combustion of the material) of the obtained foam plate can be improved.

Examples of the diphenylenyl alkane include 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3, and the like. 4-diethyl-3,4-diphenylhexane may be mentioned. Examples of the diphenyl alkene include 2,4-diphenyl-4-methyl-1-pentene and 2,4-diphenyl-4-ethyl-1-pentene. Examples of the polyalkylenebenzene include poly-1,4-diisopropylbenzene (CCPIB). Among these, poly-1,4-diisopropylbenzene (CCPIB) is preferable.

Examples of the radiation suppressing agent include fine powdery ones 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. it can. These can be used alone or in combination of two or more.

(Method for manufacturing polystyrene resin foam plate)
Hereinafter, one embodiment of the method for producing a polystyrene resin foam plate of the present invention will be described. The method for producing a polystyrene-based resin foam plate of the present invention comprises a step of extrusion-foaming a foamable molten resin composition obtained by kneading a polystyrene-based resin, a physical foaming agent, a flame retardant and other additives to form a plate. The method including is adopted.

Specifically, a polystyrene resin and, if necessary, additives such as a flame retardant, a cell regulator, a heat stabilizer, and a flame retardant auxiliary are supplied to an extruder, heated, kneaded, and further a physical foaming agent. Is pressed into an extruder, and the expandable polystyrene resin molten 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 be foamed, Molding die placed at the exit of the die (shape forming device (guider) composed of two upper and lower plates made of polytetrafluoroethylene resin or the like installed in parallel or gradually expanding from the entrance to the exit) A method of manufacturing a polystyrene resin extruded foam plate (hereinafter, sometimes referred to as a master plate) by molding it into a plate shape by passing it through a molding tool such as a molding roll or a molding roll can be adopted. Further, the width, length and thickness can be adjusted by cutting the extruded foam plate (original plate) obtained by this method to obtain a plate-shaped polystyrene resin extruded foam plate of a desired size. ..

The physical properties of the extruded polystyrene resin foam plate of the present invention will be described below.

(Apparent density)
The polystyrene resin foam plate of the present invention has a ratio ((I)/( of apparent density (I) of the surface layer portion up to 5 mm from the surface of the extruded foam plate to the apparent density (II) of the entire extruded foam plate). II)) is more than 1.10. When the ratio of the apparent densities ((I)/(II)) is within the above range, it means that a high density layer having a high apparent density is formed on the surface layer portion of the extruded foam plate. Therefore, in the foamed plate of the present invention, the amount of butane in the foamed plate was small, and the apparent density ratio ((I)/(II)) was within the above range, so that the foamed plate was scattered by welding or the like. It is considered that the resin has a high degree of flame retardancy even under more severe conditions such as the assumption that a spark comes into contact with it. In addition, the extruded foam plate also has excellent mechanical strength.
From the above viewpoint, the ratio ((I)/(II)) of the apparent density (I) of the surface layer portion and the apparent density (II) of the entire extruded foam plate is preferably more than 1.15, and more than 1.20. More preferably, it is more preferably more than 1.25. The upper limit of the apparent density ratio ((I)/(II)) is about 1.5.

The polystyrene resin extruded foam plate of the present invention uses a physical foaming agent containing a specific amount of an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms in addition to hydrofluoroolefin and another physical foaming agent as a physical foaming agent. As a result, the ratio ((I)/(II)) of the overall apparent density (II) to the apparent density (I) of the surface layer portion satisfies the above range. The reason for this is not clear, but it is considered that the foaming rate of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms is higher than that of the hydrofluoroolefin.
On the other hand, an extruded foam plate produced using a physical foaming agent containing a hydrofluoroolefin and another physical foaming agent and containing no aliphatic saturated hydrocarbon having 3 to 5 carbon atoms has the above ratio ((I)/( II)) is less than 1.10, and it is assumed that a high-density layer with a high apparent density is not formed on the surface layer of the extruded foam plate and sparks scattered by welding or the like come into contact with each other under more severe conditions. Flame resistance may be insufficient.

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

Preferably extruded polystyrene resin foam plate overall apparent density (II) is 20 to 50 kg / ^{m 3,} more preferably from 25~45kg / ^{m 3,} still to be 30-40 kg / ^{m 3} preferable.

The entire apparent density of the extruded foam plate is based on JIS K7222 (2005), and is a value obtained by dividing the weight of the polystyrene resin foam plate by the volume obtained from the outer dimensions of the foam plate in unit conversion (kg/m ³ ). Desired.

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

(Average bubble diameter)
The polystyrene-based resin extruded foam plate of the present invention has an average cell diameter in the thickness direction of the surface layer portion of 2 mm in the thickness direction from the surface of the extruded foam plate of 60 to 100 μm, and the thickness of the extruded foam plate at the center in the thickness direction. The average bubble diameter in the direction preferably exceeds 100 μm. When the average cell diameter in the thickness direction of the extruded foam plate is within the above range, the foam plate is more excellent in heat insulating property and moldability. In particular, it is considered that a layer having a high apparent density is likely to be formed in the surface layer portion because 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 small. Therefore, the flame retardancy under more severe conditions such as the assumption that sparks scattered by welding or the like come into contact with each other becomes better. 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 part in the thickness direction of the extruded foam plate, and the value is 60 to It is considered that the reason why the thickness falls within the range of 100 μm is that an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, which is a foaming agent having a higher foaming rate than hydrofluoroolefin, is used.
From the above viewpoint, 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 further 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 plate is more preferably more than 150 μm, further preferably more than 200 μm. The upper limit of the average cell diameter in the thickness direction of the central portion of the extruded foam plate in the thickness direction is about 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, 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, and the individual bubbles existing in a cross-sectional area perpendicular to the extrusion direction of the test piece (a vertical cross section orthogonal to the extrusion direction of the foam plate) On the other hand, two straight lines that are orthogonal to the thickness direction and circumscribe the 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. This is divided into 10 parts in the width direction of the foam plate, and measurement is performed on 10 test pieces cut out from the vicinity of the central part, and the arithmetic mean value is measured from the surface of the extruded foam plate to the surface layer portion up to 2 mm in the thickness direction. The average bubble diameter of

The average cell diameter in the central portion of the extruded foam plate in the thickness direction means the cell diameter obtained by the following measuring method. First, a portion up to 2.5 mm (total thickness 5 mm) in each surface direction from a straight line bisecting the foam plate in the thickness direction is cut out to obtain a test piece, and a cross-sectional area perpendicular to the extrusion direction of the test piece (of the foam plate For each bubble present in a vertical cross section orthogonal to the extrusion direction), two straight lines that are orthogonal to the thickness direction and circumscribe the 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. This is divided into 10 equal parts in the width direction of the foam plate, and measurement is performed on 10 test pieces cut out from the vicinity of the center part, and the arithmetic mean value is taken as the average cell diameter in the center part in the thickness direction of the extruded foam plate. ..

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

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

The density ρ (g/cm ³ ) of the resin composition was obtained by performing an operation of defoaming air bubbles in the test piece used for measurement and the test piece used for measurement by defoaming the air bubbles, and then obtaining the sample. Can be determined from the volume (cm ³ ).

(Thermal conductivity)
The thermal conductivity of the polystyrene resin foam plate 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 plate 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 described in JIS A1412-2 (1999) (two heat flow meters, high temperature side 38°C, low temperature side 8°C, average temperature 23°C). can do.

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

(Flammability test (spark))
The polystyrene-based resin extruded foam plate of the present invention has better flame retardancy under more severe conditions such as the assumption that sparks scattered by welding or the like come into contact. The combustion test under such conditions can be performed, for example, using fireworks as a fire source. Specifically, a firework is installed at a distance of 20 mm from the surface of the extruded foam plate so that the fireworks tip comes, and the fireworks are ignited, and sparks are applied to the surface of the foam plate 30 seconds later, and then the surface of the foam plate. Can be observed and the presence or absence of ignition can be confirmed.

Hereinafter, the method for producing the polystyrene-based resin foam plate of the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the examples.

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

The following materials were used as the materials 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), Dai-ichi Kogyo Seiyaku, trade name "Pyroguard SR130"
Flame retardant 2: Tetrabromobisphenol-A-bis(2,3-dibromopropyl ether), Dai-ichi Kogyo Seiyaku, trade name "Pyroguard SR720"
A mixture of the above flame retardant 1 and flame retardant 2 in a weight ratio of 60:40 was used as the flame retardant.

[Physical foaming 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 (trans HFO-1234ze)
Other foaming agents: dimethyl ether (DME), ethanol (EtOH), water, carbon dioxide, chloromethane (MeCl)

[Additive]
Bubble control agent: talc (Matsumura Sangyo, product name "High Filler #12")
Coloring agent: Gray MB (PSX-ET4217B, manufactured by Nikko Vix Co., Ltd.)

(Manufacturing conditions)
Polystyrene resin, flame retardant, and each additive were supplied to the first extruder of the above apparatus so as to have the blending amounts and blending amounts shown in Tables 1 and 2, and the mixture was heated to 200° C. and kneaded, and the foaming agent was poured. From the inlet, the physical foaming agent having the blending composition and blending amount shown in Table 1 was supplied to the melt and further kneaded. Then, the foamable resin melt is sequentially supplied to the second extruder, and the temperature of the extruded resin is suitable for foaming (113° C.: foaming property measured at the position of the joint between the extruder and the die). After adjusting the temperature of the resin melt), it is extruded from the die lip into the guider at the die pressure shown in Tables 1 and 2 at a discharge rate of 700 kg/hr, passed through the guider to be shaped into a plate (shape), and has a width of 1050 mm. A polystyrene foam extruded foam plate (original plate) having a thickness of 55 mm was obtained. Further, immediately after production, the original plate was adjusted to have 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 adjusting the thickness of the foam plate, each surface of the foam plate was cut by about 2 mm. After that, the foamed plate after cutting was transferred to a constant temperature and humidity chamber at 23° C. and a relative humidity of 50%, and the foamed plate was allowed to stand in the constant temperature and humidity chamber.

Regarding the obtained polystyrene resin foam plates of Examples 1 to 11 and Comparative Examples 1 to 7, surface layer physical properties (average cell diameter, apparent density), overall physical properties of the foam plate (average cell diameter, apparent density), closed cells The rate, foaming state, density ratio, thermal conductivity, flammability 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. In the following measurement and evaluation of the extruded foam plate, a 2 mm portion cut from the surface of the foam plate (original plate) formed into a plate shape by passing through the guider was used.

(Physical properties of surface layer)
[Average cell diameter in thickness direction]
It was determined according to the above method. First, a test piece (width 5 mm x thickness 2 mm) is cut out from the surface of the foam plate up to 2 mm in the thickness direction, and the test piece has a vertical cross-sectional area in the extrusion direction (a vertical cross section orthogonal to the extrusion direction of the foam plate). For each individual bubble existing in, the two straight lines that are orthogonal to the thickness direction and circumscribe the 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 obtain the bubble diameter in the thickness direction. In the above measurement, the foam plate is divided into 10 equal parts in the width direction, and 10 test pieces cut out from the vicinity of the center are measured, and the arithmetic mean value is measured from the surface of the extruded foam plate to 2 mm in the thickness direction. The average cell diameter of the surface layer was used.
[Apparent density]
For a test piece (width 50 mm×length 50 mm×thickness 5 mm) cut out in a thickness direction of 5 mm from the surface of the extruded foam plate, the apparent density was obtained from the weight and the external dimension of the test piece, and the arithmetic mean was calculated. In the above measurement, the foamed plate was divided into 10 equal parts in the width direction, and 10 test pieces cut out from the vicinity of the central portion were measured, and the arithmetic mean value was taken as the apparent density of the surface layer portion.

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

(Closed cell ratio)
Three test pieces (width 25 mm x length 25 mm x thickness 40 mm) were cut out from the vicinity of the center in the width direction of the extruded foam plate, and the closed cell ratio was measured by the above method and arithmetically averaged.

(Foamed state)
The foamed state of the extruded foam plate was evaluated according to the following criteria.
◯: No cracks, spots, etc. ×: Poor appearance, cracks, spots, etc.

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

(Thermal conductivity)
Three pieces of 200 mm wide, 200 mm long, and 50 mm thick were cut out from the center of the extruded foam plate in the width direction, and the flat plate heat flow meter method (heat flow meter two-sheet method, high temperature side 33) described in JIS A1412-2 (1999) was used. C., low temperature side 13.degree. C., average temperature 23.degree. C.), thermal conductivity was measured and arithmetically averaged.

(Combustion test (flame))
The combustion test of contacting with a flame was performed under the following conditions according to 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 center of the extruded foam plate in the width direction, and an ignition limit indicator line and a combustion limit indicator line were attached to the test pieces. The candle for a fire source had a thickness of about 20 mm and a core length of 10 mm, and a flame length of 50 mm or more and a thickness of about 7 mm or more.
The candle was moved to the ignition limit indicator line at a uniform speed over about 5 seconds, and after reaching the indicator line, the flame was retracted. The time from that moment until the flame was extinguished was measured, the presence or absence of residual dust and the stop position of combustion were confirmed, and the evaluation was made according to the following criteria.
1. The average value of the extinction time of 5 test pieces is 3 seconds or less.2. No dust left 3. Those satisfying the above 1 to 3 which did not exceed the combustion limit indicator line were evaluated as pass: ◯, and those satisfying any of the above 1 to 3 were rejected: x.

(Oxygen index)
The oxygen index was measured according to the combustion test method for polymer materials by the oxygen index method described in JIS K7201-2 (2007). Five test pieces having a size of width 10×length 150×thickness 10 mm were cut out from the center portion in the width direction of the extruded foam plate, preliminarily adjusted under a temperature of 60° C. for 4 weeks, and then the temperature was 23° C. and the relative humidity was 50. What was adjusted with% for 168 hours was used. A flame retardance tester (ON-1D type manufactured by Suga Test Instruments Co., Ltd.) was used as a measuring instrument. The values obtained for the three test pieces were arithmetically averaged.

(Flammability 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 center portion in the width direction of the extruded foam plate.
As a test device, a firework is installed at a distance of 20 mm from the surface of the test piece so that the tip of the firework comes, the firework is ignited, and the spark is applied to the surface of the test piece for 30 seconds, and then the state of the surface of the test piece is measured. The following criteria were evaluated.
When the surface of the test piece burned for 3 seconds or longer due to sparks, it was determined that the material was ignited, and it was determined to be unacceptable. Further, the case where the surface did not ignite even when melted was regarded as a pass, and the case where all five test pieces were passed was indicated as ◯.

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

From the results shown in Table 1, the production was carried out using a physical foaming agent having a hydrofluoroolefin, an aliphatic saturated hydrocarbon having 3 to 5 carbon atoms, and another foaming agent in the compounding amount and the compounding ratio defined by the present invention. The foam plates of Examples 1 to 11 had a high oxygen index and did not burn even when the sparks were in direct contact. Further, the foamed plate of the present invention had a high degree of flame retardancy even when the flame retardant content was small or not.

On the other hand, from the results shown in Table 2, the foam plates of Comparative Examples 1 to 5 in which the butane blending amount exceeds 10 mol% with respect to the total blending amount of the physical blowing agent had the high density layer in the surface layer portion, The content of butane in the foam plate was high, and the flame retardance 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 compounded were inferior in flame retardancy to sparks than Examples in which isobutane was compounded. 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 plate is smaller than the value specified in the present invention.

From these results, according to the polystyrene resin extruded foam plate of the present invention, it is assumed that the aliphatic saturated carbonization contains a specific aliphatic saturated hydrocarbon, hydrofluoroolefin and another foaming agent as the physical foaming agent. A polystyrene-based resin extruded foam board that has a specific amount of hydrogen and hydrofluoroolefin and that defines the apparent density of the surface layer part relative to the apparent density of the entire polystyrene-based resin extruded foam board is excellent in heat insulation and lightweight. It was confirmed that it has high flame retardancy.

Claims (7)

A polystyrene resin extruded foam plate obtained by extruding a polystyrene resin by 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 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,
The ratio of the blending 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 100 mol% in total of the blending amount of the physical foaming agent,
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 plate and the apparent density (II) of the entire extruded foam plate exceeds 1.10. A polystyrene resin extruded foam plate characterized by: The polystyrene-based resin extruded foam plate 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. Molar ratio ((A)/(B)) of the blending amount (A) of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms to 1 kg of the polystyrene resin and the blending amount (B) of hydrofluoroolefin to 1 kg of the polystyrene resin. ) Is 0.5 or less, The polystyrene-based resin extruded foam plate according to claim 1 or 2, wherein. 4. The compounding amount of the aliphatic saturated hydrocarbon having 3 to 5 carbon atoms is 0.05 to 0.09 mol with respect to 1 kg of polystyrene-based resin. Polystyrene resin extruded foam board. The polystyrene-based resin extruded foam plate according to any one of claims 1 to 4, wherein the hydrofluoroolefin is 1-chloro-3,3,3-trifluoropropene. 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 100 μm. The polystyrene-based resin extruded foam plate according to any one of claims 1 to 5, wherein Extruded polystyrene resin foam plate according to any one of claims 1 to 6, wherein the apparent density of the entire extruded foam plate (II) is characterized in that it is a 20 to 50 kg / m ^3.