JP7011422B2 - Styrene-based resin extruded foam and its manufacturing method - Google Patents

Description

The present invention relates to a styrene resin extruded foam obtained by extrusion foaming using a styrene resin and a foaming agent, and a method for producing the same.

In a styrene-based resin extruded foam, generally, a styrene-based resin composition is heated and melted using an extruder or the like, a foaming agent is added under high pressure conditions, the mixture is cooled to a predetermined resin temperature, and then the styrene resin composition is subjected to low pressure. Manufactured continuously by extruding into the region.

The styrene-based resin extruded foam is used, for example, as a heat insulating material for a structure because of its good workability and heat insulating properties. In recent years, there has been an increasing demand for energy saving in houses and buildings, and there is a demand for technological development of higher heat insulating foam than before.

As a method for producing a highly heat-insulating foam, a method of controlling the bubble diameter of the extruded foam within a predetermined range (for example, Patent Document 1) and a method of adding a heat ray radiation inhibitor (for example, Patent Documents 2 to 2). 3), a method using a foaming agent having a low thermal conductivity (for example, Patent Documents 4 to 6) has been proposed.

Among the above, as a method of using a foaming agent having a low thermal conductivity, an environment-friendly fluorinated olefin (hydrofluoroolefin, which has an ozone depletion potential of 0 (zero) and a small global warming potential) is used. A method for producing a styrene-based resin extruded foam using HFO) has been proposed. However, since the hydrofluoroolefins used in these conventional techniques have low solubility in styrene-based resins and are quickly separated from the styrene-based resins during extrusion foaming, the separated hydrofluoroolefins serve as nucleating points and bubbles. As the diameter becomes finer, the deformation / movable range for extruding foam to give shape becomes smaller, and there is a problem that it is not easy to give a beautiful surface to the extruded foam and to give thickness. .. Furthermore, the adiabatic expansion of the hydrofluoroolefin causes the resin to be cooled and solidified (elongation becomes poor), and the elongation of the resin itself deteriorates, making it more difficult to impart a beautiful surface to the extruded foam and to increase its thickness. There was a problem. Patent Document 6 proposes a method for producing a styrene-based resin extruded foam having excellent heat insulating properties and moldability by using hydrofluoroolefin, saturated hydrocarbon, and water or carbon dioxide in combination. However, in the range of blending the foaming agent of the prior art, the amount of the foaming agent used is large, and particularly when graphite is used as the heat ray radiation inhibitor, the extruded foam cannot be imparted with suitable flame retardancy. Since hydrofluoroolefins are not completely nonflammable, flame retardancy when a styrene resin extruded foam is used unless a suitable range is selected in combination with a foaming agent used in combination or with a heat ray radiation inhibitor. Had a problem that impaired.

As described above, all of the conventional techniques for producing a highly heat-insulating foam deteriorate the deformation of the foam and / or the elongation of the resin itself when the extruded foam is extruded and foamed for molding. Since there was a problem with the surface properties and thickness of the extruded foam, a styrene resin extruded foam having excellent heat insulating properties and flame retardancy, and having a beautiful appearance and / or a sufficient thickness was obtained. It was not easily obtained and still had problems.

JP-A-2004-59595 JP 2013-221110 JP 2015-11316 Special table 2008-546892 WO2015 / 093195 JP 2013-194101

An object of the present invention is to easily obtain a styrene-based resin extruded foam having excellent heat insulating properties and flame retardancy, having a beautiful appearance, and having a sufficient thickness suitable for use.

As a result of diligent studies to solve the above problems, the present inventors have completed the present invention.

That is, one embodiment of the present invention has the following configuration.
[1] A styrene resin extruded foam containing a flame retardant of 0.5 parts by weight or more and 8.0 parts by weight or less with respect to 100 parts by weight of the styrene resin.
It contains saturated hydrocarbons with 3 to 5 carbon atoms and hydrofluoroolefins as foaming agents.
(I) The residual amount of hydrofluoroolefin in the extruded styrene resin foam is 0.41 mol or more and 0.80 mol or less per 1 kg of the extruded foam.
(II) The residual amount of saturated hydrocarbons having 3 to 5 carbon atoms in the styrene-based resin extruded foam is 0.05 mol or more and 0.35 mol or less per 1 kg of the extruded foam.
(III) The total amount of the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the styrene-based resin extruded foam is 0.46 mol or more and 0.90 mol or less per 1 kg of the extruded foam. A styrene-based resin extruded foam, characterized in that it is.
[2] The styrene-based resin extruded foam according to [1], which contains graphite in an amount of 1.0 part by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the styrene-based resin.
[3] Further, as the foaming agent, at least one of the group consisting of dimethyl ether, ethyl chloride, and methyl chloride is contained in an amount of 0.5 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the styrene resin [1] or. The styrene-based resin extruded foam according to [2].
[4] The styrene-based resin extruded foam according to any one of [1] to [3], wherein at least one of the saturated hydrocarbons having 3 to 5 carbon atoms is isobutane.
[5] The styrene-based resin extruded foam according to any one of [1] to [4], wherein the hydrofluoroolefin is tetrafluoropropene.
[6] The styrene-based resin extruded foam according to any one of [1] to [5], which has a thickness of 10 mm or more and 150 mm or less.
[7] The styrene-based resin extruded foam according to any one of [1] to [6], wherein the apparent density is 20 kg / m ³ or more and 60 kg / m ³ or less, and the closed cell ratio is 90% or more.
[8] The styrene-based resin extruded foam according to any one of [1] to [7], which contains 0.5 parts by weight or more and 5.0 parts by weight or less of a bromine-based flame retardant with respect to 100 parts by weight of the styrene-based resin. body.
[9] The method for producing an extruded styrene resin foam according to any one of [1] to [8].

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to easily obtain a styrene-based resin extruded foam having excellent heat insulating properties and flame retardancy, having a beautiful appearance, and having a sufficient thickness suitable for use.

An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope of the claims. Further, the technical scope of the present invention also includes embodiments and / or examples obtained by appropriately combining the technical means disclosed in different embodiments and / or examples. In addition, all the academic and patent documents described in the present specification are incorporated as references in the present specification. Further, unless otherwise specified in the present specification, "A to B" representing a numerical range is intended to be "A or more (including A and larger than A) and B or less (including B and smaller than B)".

[1. Styrene-based resin extruded foam]
The styrene-based resin extruded foam of the present invention is a styrene-based resin extruded foam containing 0.5 parts by weight or more and 8.0 parts by weight or less of a flame retardant with respect to 100 parts by weight of the styrene-based resin, and is used as a foaming agent. It contains saturated hydrocarbons having 3 to 5 carbon atoms and hydrofluoroolefins. Further, if necessary, the styrene resin composition containing an appropriate amount of other additives is heated and melted using an extruder or the like, and then a foaming agent is added under high pressure conditions and cooled to a predetermined resin temperature. , It is continuously manufactured by extruding it into the low pressure range.

(1-1. Styrene resin)
The styrene-based resin used in one embodiment of the present invention is not particularly limited, and (i) styrene such as styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, bromostyrene, chlorostyrene, vinyltoluene, vinylxylene and the like. A homopolymer of a system monomer or a copolymer composed of a combination of two or more types of monomers, or (ii) the styrene-based monomer and divinylbenzene, butadiene, acrylic acid, methacrylic acid, methyl acrylate. , A copolymer obtained by copolymerizing one or more of monomers such as methyl methacrylate, acrylonitrile, maleic anhydride, and itaconic anhydride. Monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, maleic anhydride, and itaconic anhydride to be copolymerized with the styrene-based monomer can be used as the compressive strength of the produced styrene-based resin extruded foam. An amount that does not deteriorate the physical properties of the above can be used. Further, the styrene-based resin used in one embodiment of the present invention is not limited to the homopolymer or copolymer of the styrene-based monomer, but the homopolymer or copolymer of the styrene-based monomer and the above-mentioned. It may be a homopolymer of other monomers or a blend with a copolymer. For example, the styrene-based resin used in one embodiment of the present invention may be a blend of a homopolymer or copolymer of the styrene-based monomer and diene-based rubber-reinforced polystyrene or acrylic rubber-based rubber-reinforced polystyrene. good. Further, the styrene-based resin used in one embodiment of the present invention is a styrene-based resin having a branched structure for the purpose of adjusting the melt flow rate (hereinafter referred to as MFR), the melt viscosity during molding, the melt tension, and the like. There may be.

As the styrene resin in one embodiment of the present invention, using a styrene resin having an MFR of 0.1 to 50 g / 10 minutes is excellent in (i) moldability during extrusion foam molding, and (ii) molding. It is easy to adjust the discharge amount at the time of processing, the thickness, width, apparent density, and closed cell ratio of the obtained styrene resin extruded foam to desired values, and (iii) foamability (thickness, width of foam, It is easy to adjust the apparent density, closed cell ratio, surface properties, etc. to the desired conditions), (iv) a styrene resin extruded foam with excellent appearance, etc. can be obtained, and (v). It is preferable from the viewpoint that a styrene resin extruded foam having a well-balanced characteristics (for example, mechanical strength such as compressive strength, bending strength or bending amount, toughness, etc.) can be obtained. Further, the MFR of the styrene resin is more preferably 0.3 to 30 g / 10 minutes, more preferably 0.5 to 25 g / 10 minutes, from the viewpoint of the balance between molding processability and foamability, mechanical strength and toughness. Especially preferable. In one embodiment of the present invention, the MFR is measured by the method A of JIS K7210 (1999) and the test condition H.

In one embodiment of the present invention, among the above-mentioned styrene-based resins, polystyrene resin is particularly suitable from the viewpoint of economy and processability. When higher heat resistance is required for the extruded foam, it is preferable to use a styrene-acrylonitrile copolymer, (meth) acrylic acid copolymer polystyrene, and maleic anhydride-modified polystyrene. Further, when the extruded foam is required to have higher impact resistance, it is preferable to use rubber-reinforced polystyrene. These styrene resins may be used alone, or two or more different styrene resins having different copolymerization components, molecular weights and molecular weight distributions, branched structures, and / or MFRs may be mixed and used. ..

(1-2. Foaming agent)
The hydrofluoroolefin used in the present invention is not particularly limited, but tetrafluoropropene is preferable from the viewpoint of low thermal conductivity and safety of the gas. Specifically, trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze), cis-1,3,3,3-tetrafluoropropene (cis-HFO-1234ze), 2,3. Examples thereof include 3,3-tetrafluoropropene (trans-HFO-1234yf). Further, the hydrofluoroolefin used in the present invention may be a chlorinated hydrochlorofluoroolefin. The hydrochlorofluoroolefin is not particularly limited, but hydrochlorotrifluoropropene is preferable from the viewpoint of low thermal conductivity and safety of the gas. Specific examples thereof include trans-1-chloro-3,3,3-trifluoropropene (trans-HCFO-1233zd). These hydrofluoroolefins may be used alone or in combination of two or more.

Examples of the saturated hydrocarbon having 3 to 5 carbon atoms used in the present invention include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane and the like. Among these saturated hydrocarbons having 3 to 5 carbon atoms, propane, n-butane, i-butane, or a mixture thereof is preferable from the viewpoint of foamability. Further, from the viewpoint of the heat insulating performance of the foam, n-butane, i-butane (hereinafter, also referred to as "isobutane"), or a mixture thereof is preferable, and i-butane is particularly preferable.

Depending on the desired foaming ratio, flame retardancy, and other characteristics of the foam, the amount of the hydrofluoroolefin or saturated hydrocarbon having 3 to 5 carbon atoms added may be limited, and extrusion foam molding may be performed. The sex may not be sufficient.

In one embodiment of the present invention, by further using another foaming agent, a plasticizing effect and / or a co-foaming effect at the time of foam production can be obtained, the extrusion pressure is reduced, and the foam can be stably produced. Is possible.

Other effervescent agents include, for example, ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, tetrahydropyran; dimethylketone, methylethylketone. , Diethyl-n-propylketone, methyl-n-butylketone, methyl-i-butylketone, methyl-n-amylketone, methyl-n-hexylketone, ethyl-n-propylketone, ethyl-n-butylketone, etc. Ketones; Saturated alcohols with 1 to 4 carbon atoms such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t-butyl alcohol; methyl formic acid ester, ethyl formic acid ester, propyl formic acid ester , Caroic acid esters such as butyl ester, amilic acid amyl ester, methyl propionate, ethyl propionate; organic foaming agents such as alkyl halides such as methyl chloride and ethyl chloride, inorganic foaming agents such as water and carbon dioxide. , Azo compounds, chemical effervescent agents such as tetrazole and the like can be used. These other foaming agents may be used alone or in combination of two or more.

Among other foaming agents, saturated hydrocarbons having 3 to 5 carbon atoms, saturated alcohols having 1 to 4 carbon atoms, dimethyl ether, diethyl ether, methyl ethyl ether, etc. Methyl chloride, ethyl chloride and the like are preferable, and water and carbon dioxide are preferable from the viewpoint of flammability of the foaming agent, flame retardancy or heat insulating property of the foam. Among these, dimethyl ether, methyl chloride, and ethyl chloride are particularly preferable from the viewpoint of the plasticizing effect, and water is particularly preferable from the viewpoint of the cost and the effect of improving the heat insulating property by controlling the bubble diameter.

When dimethyl ether, methyl chloride, and ethyl chloride are used as other foaming agents in the present invention, the amount thereof is preferably 0.5 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the styrene resin. It is more preferably 9.0 parts by weight or more and 10 parts by weight or less, and particularly preferably 2.0 parts by weight or more and 8.0 parts by weight or less. If the amount of dimethyl ether, methyl chloride, and ethyl chloride added is less than 0.5 parts by weight with respect to 100 parts by weight of the styrene resin, the amount added is too small, and it is difficult to obtain the effect of improving the foamability and moldability of the extruded foam. .. When the amount of dimethyl ether, methyl chloride, and ethyl chloride added exceeds 15 parts by weight with respect to 100 parts by weight of the styrene resin, the amount remaining in the obtained extruded foam is too large and the flame retardancy is deteriorated. There is a risk of causing it.

The amount of the foaming agent added in one embodiment of the present invention is preferably 2.0 parts by weight or more and 20 parts by weight or less, and 2.0 parts by weight or more and 15 parts by weight with respect to 100 parts by weight of the styrene resin as a whole. Less than a portion is more preferable. If the amount of the foaming agent added is less than 2.0 parts by weight, the foaming ratio is low, and it may be difficult to exhibit characteristics such as lightness and heat insulating properties as a resin foam. If it is more than 20 parts by weight, it is excessive. Due to the large amount of foaming agent, defects such as voids may occur in the foam.

The present invention contains saturated hydrocarbons having 3 to 5 carbon atoms and hydrofluoroolefins as foaming agents.
(I) The residual amount of hydrofluoroolefin in the extruded styrene resin foam is 0.41 mol or more and 0.80 mol or less per 1 kg of the extruded foam.
(II) The residual amount of saturated hydrocarbons having 3 to 5 carbon atoms in the styrene-based resin extruded foam is 0.05 mol or more and 0.35 mol or less per 1 kg of the extruded foam.
(III) The total amount of the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the styrene resin extruded foam is 0.46 mol or more and 0.90 mol or less per 1 kg of the extruded foam. Is.

In one embodiment of the present invention, the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms in the styrene resin extruded foam is 0.05 mol or more and 0.35 mol or less per 1 kg of the extruded foam, and 0. It is preferably 05 mol or more and 0.30 mol or less, and more preferably 0.10 mol or more and 0.25 mol or less. When the residual amount of saturated hydrocarbon having 3 to 5 carbon atoms in the styrene resin extruded foam is less than 0.05 mol per 1 kg of the extruded foam, the saturated hydrocarbon having 3 to 5 carbon atoms in the foam is used. The amount of is too small to obtain a foam of the desired thickness. When the residual amount of saturated hydrocarbon having 3 to 5 carbon atoms in the styrene resin extruded foam exceeds 0.40 mol per 1 kg of the extruded foam, the foam has 3 to 5 carbon atoms which is a flammable gas. Since the amount of the saturated hydrocarbon of 5 is too large, the desired flame retardancy cannot be imparted.

In one embodiment of the present invention, the residual amount of hydrofluoroolefin in the styrene resin extruded foam is 0.41 mol or more and 0.80 mol or less, and 0.41 mol or more and 0.70 mol or less per 1 kg of the extruded foam. It is preferably 0.41 mol or more and 0.65 mol or less, more preferably 0.41 mol or more. When the residual amount of hydrofluoroolefin in the styrene-based resin extruded foam is less than 0.41 mol per 1 kg of the extruded foam, the amount of hydrofluoroolefin in the foam is too small, and the desired heat insulating property can be obtained. do not have. When the residual amount of hydrofluoroolefin in the extruded styrene resin foam exceeds 0.80 mol per 1 kg of the extruded foam, the amount of hydrofluoroolefin in the foam is too large, and the moldability deteriorates, which is desired. An extruded foam having the appearance of is not obtained.

Hydrofluoroolefins have an ozone depletion potential of zero or extremely small, have a very small global warming potential, and are environmentally friendly foaming agents. Moreover, since hydrofluoroolefins have low thermal conductivity in a gaseous state and are flame-retardant (however, they are not completely nonflammable), they are excellent when used as a foaming agent for styrene-based resin extruded foams. It is possible to impart heat insulating properties, and it is easier to impart excellent flame retardancy than when a conventional flammable gas is used.

On the other hand, when a hydrofluoroolefin having low solubility in a styrene resin such as the above-mentioned tetrafluoropropene is used, the hydrofluoroolefin is separated from the resin melt and vaporized as the amount of addition is increased, thereby forming a nucleus. As a point, the bubbles in the foam become finer, the foaming agent remaining in the resin decreases, the plasticizing effect on the resin melt decreases, and the resin melt cools and solidifies due to the adiabatic expansion of the foam. When it occurs, it tends to be difficult to give a beautiful surface to the extruded foam and to give it a thickness.

In one embodiment of the present invention, the total amount of the residual amount of saturated hydrocarbon having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the styrene resin extruded foam is 0. It is 46 mol or more and 0.90 mol or less, preferably 0.46 mol or more and 0.85 mol or less, and more preferably 0.50 mol or more and 0.80 mol or less. When the total amount of the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the styrene resin extruded foam is less than 0.46 mol, the amount of foaming agent in the foam is The amount is too small to obtain the desired heat insulating property. When the total amount of the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the styrene resin extruded foam exceeds 0.90 mol, the hydrofluoroolefin is completely nonflammable. Rather, the amount of the remaining foaming agent in the extruded foaming is too large, so that the flame retardancy deteriorates.

The content of saturated hydrocarbons having 3 to 5 carbon atoms and the content of hydrofluoroolefins in the styrene-based resin extruded foam may gradually decrease immediately after production. It is considered that this is because saturated hydrocarbons having 3 to 5 carbon atoms and hydrofluoroolefins are gradually disappearing from the styrene resin extruded foam immediately after production, particularly from the surface thereof. However, the disappearance is a phenomenon that occurs immediately after production, and hardly occurs after 7 days from production. In other words, after 7 days have passed from the production, the content of saturated hydrocarbons having 3 to 5 carbon atoms and the content of hydrofluoroolefins in the styrene-based resin extruded foam may be considered to be substantially constant. .. Therefore, in one embodiment of the present invention, the content of saturated hydrocarbon having 3 to 5 carbon atoms and the content of hydrofluoroolefin in the styrene resin extruded foam are the same after 7 days have passed from the production. It may be a content.

According to the present invention, foaming is performed by controlling the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms, the residual amount of hydrofluoroolefins, and the total amount of these residual amounts in the styrene resin extruded foam. It is possible to obtain a thick foam while imparting excellent heat insulating properties and flame retardancy to the body.

As a preferred embodiment of the present invention, a saturated hydrocarbon having 3 to 5 carbon atoms and a hydrofluoroolefin used as a foaming agent are contained in a predetermined amount, and at least one of the group consisting of dimethyl ether, ethyl chloride and methyl chloride is contained. As a result, the surface properties and thicknessing properties of the extruded foam (that is, the formability of the extruded foam), which deteriorates when hydrofluoroolefins are used as the foaming agent, are improved, and the extruded foam has excellent heat insulating properties and flame retardancy. A styrene-based resin extruded foam can be obtained. If a large amount of hydrofluoroolefin is used to improve heat insulation, the moldability of the extruded foam deteriorates. Therefore, the residual amount of hydrofluoroolefin is usually suppressed to the above amount, and the number of carbon atoms is further increased. Good moldability of the extruded foam can be ensured by containing 3 to 5 saturated hydrocarbons and at least one of the group consisting of dimethyl ether, ethyl chloride and methyl chloride.

In order to control the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the styrene resin extruded foam within the predetermined amount range specified in the present invention as described above, carbon is used. The blending amount, extrusion temperature, foaming pressure, etc. of the saturated hydrocarbons of the number 3 to 5 and the hydrofluoroolefin may be adjusted. In order to increase the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and hydrofluoroolefins by adjusting the extrusion temperature and foaming pressure, it is sufficient to keep the extrusion temperature low and the foaming pressure high, and conversely, carbon. In order to reduce the residual amounts of saturated hydrocarbons and hydrofluoroolefins of Nos. 3 to 5, the extrusion temperature may be increased and the foaming pressure may be decreased.

In one embodiment of the present invention, when water and / or alcohols are used as other foaming agents, it is preferable to add a water-absorbent substance in order to stably perform extrusion foam molding. Specific examples of the water-absorbent substance used in one embodiment of the present invention include a polyacrylic acid salt-based polymer, a starch-acrylic acid graft copolymer, a polyvinyl alcohol-based polymer, and a vinyl alcohol-acrylic acid salt-based copolymer. Water-absorbent polymers such as coalesced, ethylene-vinyl alcohol-based copolymers, acrylonitrile-methyl methacrylate-butadiene-based copolymers, polyethylene oxide-based copolymers and derivatives thereof, as well as anhydrous silica having a silanol group on the surface. (Silicon oxide) [For example, AEROSIL manufactured by Nippon Aerosil Co., Ltd. is commercially available], which is a fine powder having a hydroxyl group on the surface and having a particle diameter of 1000 nm or less; Examples thereof include swellable layered silicates and their organically treated products; porous substances such as zeolites, activated carbons, aluminas, silica gels, porous glass, active white clay, diatomaceous clay, and bentonite. The amount of the water-absorbent substance added is appropriately adjusted depending on the amount of water and / or alcohol added, but is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the styrene resin. 0.1 to 3 parts by weight is more preferable.

In the method for producing a styrene resin extruded foam according to an embodiment of the present invention, the pressure at which the foaming agent is added or injected is not particularly limited, and may be higher than the internal pressure of an extruder or the like. Just do it.

(1-3. Flame retardant)
In one embodiment of the present invention, the styrene resin obtained by containing 0.5 part by weight or more and 8.0 parts by weight or less of the flame retardant with respect to 100 parts by weight of the styrene resin in the styrene resin extruded foam. Flame retardancy can be imparted to the extruded foam. If the content of the flame retardant is less than 0.5 parts by weight, it tends to be difficult to obtain good properties as a foam such as flame retardancy, while if it exceeds 8.0 parts by weight, foam production is produced. It may impair the stability and surface properties of the product. However, the content of the flame retardant is the type of foaming agent added, the apparent density of the foam, the additive having a flame retardant synergistic effect, etc. so that the flame retardancy specified in JIS A 9521 measurement method A can be obtained. Alternatively, it is more preferable to adjust appropriately according to the content and the like.

As the flame retardant, a brominated flame retardant is preferably used. Specific examples of the brominated flame retardant in one embodiment of the present invention include hexabromocyclododecane, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether, and tetrabromobisphenol A-bis. Examples include aliphatic bromine-containing polymers such as (2,3-dibromopropyl) ether, tris (2,3-dibromopropyl) isocyanurate, and brominated styrene-butadiene block copolymers. These may be used alone or in combination of two or more.

Among these, a mixed brominated flame retardant composed of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether, brominated. The styrene-butadiene block copolymer and hexabromocyclododecane are preferably used because they have good extrusion operation and do not adversely affect the heat resistance of the foam. These substances may be used alone or as a mixture.

The content of the bromine-based flame retardant in the styrene-based resin extruded foam according to the embodiment of the present invention is preferably 0.5 parts by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the styrene-based resin, and styrene. It is more preferably 1.0 part by weight or more and 5.0 parts by weight or less, and further preferably 1.5 parts by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the based resin. When the content of the brominated flame retardant is less than 0.5 parts by weight, it tends to be difficult to obtain good properties as a foam such as flame retardancy, while when it exceeds 5.0 parts by weight, foaming tends to occur. It may impair the stability and surface properties of the body during manufacturing.

In one embodiment of the present invention, a radical generator can be used in combination for the purpose of improving the flame retardant performance of the styrene resin extruded foam. Specifically, the radical generator is 2,3-dimethyl-2,3-diphenylbutane, poly-1,4-diisopropylbenzene, 2,3-diethyl-2,3-diphenylbutane, 3,4-. Dimethyl-3,4-diphenylhexane, 3,4-diphenyl-3,4-diphenylhexane, 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-ethyl-1-pentene, etc. Can be mentioned. Peroxides such as dicumyl peroxide are also used. Among them, those which are stable under the resin processing temperature conditions are preferable, and specifically, 2,3-dimethyl-2,3-diphenylbutane and poly-1,4-diisopropylbenzene are preferable, and the radical generators mentioned above. The preferable amount to be added is 0.05 to 0.5 part by weight with respect to 100 parts by weight of the styrene resin.

Further, for the purpose of improving the flame retardant performance, in other words, as a flame retardant aid, a phosphorus-based flame retardant such as a phosphoric acid ester and a phosphine oxide can be used in combination as long as the thermal stability performance is not impaired. Phosphate esters include triphenyl phosphate, tris (tributylbromoneopentyl) phosphate, tricresyl phosphate, trixylylenyl phosphate, cresyldiphenyl phosphate, 2-ethylhexyldiphenyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, etc. Examples thereof include tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate, condensed phosphate ester and the like, and triphenyl phosphate or tris (tributylbromoneopentyl) phosphate is particularly preferable. Further, as the phosphine oxide type phosphorus flame retardant, triphenylphosphine oxide is preferable. These phosphate esters and phosphine oxides may be used alone or in combination of two or more. The preferable amount of the phosphorus-based flame retardant to be added is 0.1 to 2 parts by weight with respect to 100 parts by weight of the styrene-based resin.

(1-4. Stabilizer)
In one embodiment of the present invention, a resin and / or a flame retardant stabilizer can be used, if necessary. Specific examples of the stabilizer include, but are not limited to, (i) an epoxy compound such as bisphenol A diglycidyl ether type epoxy resin, cresol novolac type epoxy resin, and phenol novolac type epoxy resin. ii) A reaction product of a polyhydric alcohol such as pentaerythritol, dipentaerythritol, tripentaerythritol and a monohydric carboxylic acid such as acetic acid or propionic acid, or a divalent carboxylic acid such as adipic acid or glutamate. A polyhydric alcohol ester, (iii) triethylene glycol-bis-3-, which is an ester, which is a mixture of esters having one or more hydroxyl groups in its molecule and may contain a small amount of the raw material polyhydric alcohol. (3-tert-Butyl-4-hydroxy-5-methylphenyl) propionate, pentaerythritol tetrakis [3- (3', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate], and octadecyl 3-. (3,5-Di-tert-butyl-4-hydroxyphenyl) Phenolic stabilizers such as propionate, (iv) 3,9-bis (2,4-di-tert-butylphenoxy) -2,4 8,10-Tetraoxa-3,9-diphosphaspiro [5.5] undecane, 3,9-bis (2,6-di-tert-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa- Phosphite-based stabilizers, such as 3,9-diphosphaspiro [5.5] undecane, and tetrakis (2,4-di-tert-butyl-5-methylphenyl) -4,4'-biphenylenediphosphonite). And the like are preferably used because they do not deteriorate the flame retardant performance of the foam and improve the thermal stability of the foam.

(1-5. Heat ray radiation inhibitor)
In the styrene resin extruded foam according to the embodiment of the present invention, graphite may be added as a heat ray radiation inhibitor in order to improve the heat insulating property. Examples of the graphite used in one embodiment of the present invention include scale-like graphite, earth-like graphite, spheroidal graphite, and artificial graphite. Among these, it is preferable to use scaly graphite as the main component because it has a high effect of suppressing heat ray radiation. Graphite preferably has a fixed carbon content of 80% or more, and more preferably 85% or more. By setting the fixed carbon content in the above range, a foam having high heat insulating properties can be obtained.

The average particle size of graphite is preferably 15 μm or less, more preferably 10 μm or less. By setting the average particle size in the above range, the specific surface area of graphite becomes large and the probability of collision with heat ray radiation becomes high, so that the effect of suppressing heat ray radiation becomes high. The average particle size is measured and analyzed by the laser diffraction scattering method based on the Mie theory based on ISO13320: 2009 and JIS Z8825: 2013, and the particle size when the cumulative volume with respect to the volume of all particles becomes 50%. It means (volume average particle size by laser diffraction scattering method).

The graphite content in one embodiment of the present invention is 1.0 part by weight or more and 5.0 parts by weight or less, and 1.5 parts by weight or more and 3.0 parts by weight or less with respect to 100 parts by weight of the styrene resin. preferable. If the content is less than 1.0 part by weight, a sufficient effect of suppressing heat ray radiation cannot be obtained. If the content exceeds 5.0 parts by weight, the effect of suppressing heat ray radiation corresponding to the content cannot be obtained, and there is no cost merit.

The heat ray radiation inhibitor refers to a substance having the property of reflecting, scattering, and absorbing light in the near infrared or infrared region. By containing a heat ray radiation inhibitor, it can be a foam having high heat insulating properties. As the heat ray radiation inhibitor that can be used in the present invention, white particles such as titanium oxide, barium sulfate, zinc oxide, aluminum oxide, and antimony oxide can be used in combination in addition to graphite. These may be used alone or in combination of two or more. Among these, titanium oxide or barium sulfate is preferable, and titanium oxide is more preferable, because the effect of suppressing radiation radiation is large. The average particle size of the white particles is not particularly limited, but is preferably 0.1 μm to 10 μm for titanium oxide, for example, in consideration of effective reflection of infrared rays and color development on the resin. , 0.15 μm to 5 μm is more preferable.

The content of the white particles in one embodiment of the present invention is preferably 1.0 part by weight or more and 3.0 parts by weight or less, and 1.5 parts by weight or more and 2.5 parts by weight with respect to 100 parts by weight of the styrene resin. More preferably, it is by weight or less. The white particles have a smaller heat ray radiation suppressing effect than graphite, and when the content of the white particles is less than 1.0 part by weight, there is almost no heat ray radiation suppressing effect even if the white particles are contained. When the content of the white particles exceeds 3.0 parts by weight, the heat ray radiation suppressing effect corresponding to the content cannot be obtained, while the flame retardancy of the foam tends to deteriorate.

The total content of the heat ray radiation inhibitor in one embodiment of the present invention is preferably 1.0 part by weight or more and 6.0 parts by weight or less, and 2.0 parts by weight or more and 5. More preferably, it is 0 parts by weight or less. If the total content of the heat ray radiation inhibitor is less than 1.0 part by weight, it is difficult to obtain heat insulating properties. On the other hand, as the content of the solid additive such as the heat ray radiation inhibitor increases, the number of nucleus forming points increases. However, it tends to be difficult to give the extruded foam a beautiful surface and to increase the thickness of the extruded foam because the bubbles of the foam become finer and the elongation of the resin itself deteriorates. When the total content of the heat ray radiation inhibitor exceeds 6.0 parts by weight, it tends to be inferior, in particular, to impart a beautiful surface to the extruded foam and to increase the thickness of the extruded foam. It tends to impair extrusion stability and flame retardancy.
(1-6. Moldability improver)
In one embodiment of the present invention, polyethylene glycol and / or a polyhydric alcohol fatty acid ester may be added as a moldability improving agent, if necessary. By using these, it is possible to impart a beautiful surface to the extruded foam and to increase the thickness of the extruded foam (that is, to improve the moldability of the extruded foam).

The average molecular weight of the polyethylene glycol used in one embodiment of the present invention is not particularly limited, but is preferably 1000 or more and 25,000 or less, more preferably 1500 or more and 20000 or less, and particularly preferably 3000 or more and 15000 or less. These polyethylene glycols having different average molecular weights may be used alone or in combination of two or more. When the average molecular weight of polyethylene glycol is less than 1000, the freezing point of polyethylene glycol is low and the polyethylene glycol is in a liquid state at room temperature. Therefore, depending on the amount used, the handling property is poor, for example, in the dry blending step during the production of extruded foam. In addition, there is a risk of affecting various properties of the extruded foam, such as the sliminess of the surface due to the bleed-out of polyethylene glycol from the inside to the surface of the extruded foam. On the other hand, when the molecular weight of polyethylene glycol is 1000 or more and 25,000 or less, the freezing point is higher than normal temperature, the handling property is excellent, bleed-out does not occur, the freezing point is lower than the extrusion foam molding temperature, and the styrene type at the time of extrusion foam molding. Since the resin can also be given a plasticizing effect, it is possible to exert a sufficient effect of imparting surface properties to the extruded foam of a styrene resin and a sufficient effect of thickening. When the molecular weight of polyethylene glycol exceeds 25,000, it exists as a solid at the extrusion foaming temperature, and it is not possible to impart a plasticizing effect to the styrene resin during extrusion foam molding, and a sufficient surface property imparting effect to the styrene resin extruded foam. , And there is a risk that sufficient thicknessing effect cannot be exhibited.

The content of polyethylene glycol in one embodiment of the present invention is preferably 0.1 parts by weight or more and 3.0 parts by weight or less, and particularly preferably 0.2 parts by weight or more and 1.0 part by weight or less. If the content of polyethylene glycol is less than 0.05 parts by weight, the effect of imparting surface properties and the effect of thickening tend to be insufficient. On the other hand, when the content of polyethylene glycol exceeds 5.0 parts by weight, the content of polyethylene glycol is excessive, which impairs the extrudability, foamability, and molding stability during manufacturing, and the heat resistance of the extruded foam. There is a risk of deteriorating various characteristics of.

Examples of the polyhydric alcohol fatty acid ester used in one embodiment of the present invention include higher fatty acids having 10 to 24 carbon atoms, ethylene glycol, glycerin, 1,2,4-butanetriol, diglycerin, pentaerythritol, and sorbitol. , Esters with polyhydric alcohols such as erythritol and hexanetriol. These polyhydric alcohol fatty acid esters may be used alone or in combination of two or more.

Among these, glycerin fatty acid ester, particularly glycerin mono, di, tri, or tetra fatty acid ester is preferable from the viewpoint of availability and price.

Examples of the glycerin fatty acid ester include lauric acid monoglyceride, lauric acid diglyceride, lauric acid triglyceride, partimate monoglyceride, partimate diglyceride, partimate triglyceride, stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, and stearic acid tetraglyceride. It is preferable to use at least one selected from the group consisting of.

The melting point of the glycerin fatty acid ester used in the present invention is preferably 150 ° C. or lower, more preferably 130 ° C. or lower, and particularly preferably 110 ° C. When the melting point of the glycerin fatty acid ester is 150 ° C. or lower, for example, it has excellent handleability in a dry blending step during extrusion foam molding and exists as a liquid during extrusion foam molding, so that it is a styrene type during extrusion foam molding. Since a plasticizing effect can be imparted to the resin, a sufficient thickening effect of the styrene-based resin extruded foam can be exhibited. On the other hand, when the melting point exceeds 150 ° C., it exists as a solid during extrusion foam molding, and the styrene resin during extrusion foam molding cannot be given a plasticizing effect, and a sufficient thickening effect of the styrene resin extruded foam is exhibited. It may not be possible.

The content of the polyhydric alcohol fatty acid ester used in one embodiment of the present invention is preferably 0.05 parts by weight or more and 5.0 parts by weight or less, and 0.1 parts by weight or more and 3 parts by weight with respect to 100 parts by weight of the styrene resin. .0 parts by weight or less is more preferable, and 0.5 parts by weight or more and less than 2.0 parts by weight is particularly preferable. If the content of the polyhydric alcohol fatty acid ester is less than 0.05 parts by weight, the thickening effect of the extruded foam tends to be insufficient. On the other hand, if it exceeds 5.0 parts by weight, the amount is excessive, which may impair the extrusion, foaming and molding stability during manufacturing, and may deteriorate various properties such as heat resistance of the extruded foam.

In one embodiment of the present invention, when polyethylene glycol and polyvalent alcohol fatty acid ester are used in combination as a moldability improving agent, the total amount of polyethylene glycol and polyvalent alcohol fatty acid ester is 100 parts by weight of the styrene resin. Is preferably 0.1 parts by weight or more and 3.0 parts by weight or less, and particularly preferably 0.2 parts by weight or more and 2.0 parts by weight or less. If the content is less than 0.05 parts by weight, the effect of imparting surface properties and the effect of thickening tend to be insufficient. On the other hand, when the content exceeds 5.0 parts by weight, the content is excessive, which impairs the extrudability, foamability, and molding stability during manufacturing, and deteriorates various properties such as heat resistance of the extruded foam. There is a risk.

(1-7. Additive)
In one embodiment of the present invention, if necessary, for example, silica, calcium silicate, wallastnite, kaolin, clay, mica, carbonic acid, to the extent that the effect according to the embodiment of the present invention is not impaired. Inorganic compounds such as calcium, sodium stearate, calcium stearate, magnesium stearate, barium stearate, liquid paraffin, olefin wax, processing aids such as stearylamide compounds, phenolic antioxidants, phosphorus stabilizers, nitrogen System stabilizers, sulfur-based stabilizers, light-resistant stabilizers such as benzotriazoles and hindered amines, bubble size adjusters such as talc, flame retardant agents other than the above, antistatic agents, colorants such as pigments, plasticizers, etc. The additive may be contained in the styrene-based resin.

The method and procedure for blending various additives with the styrene resin include, for example, a method of adding various additives to the styrene resin and mixing them by dry blending, and melting from a supply unit provided in the middle of the extruder. A method of adding various additives to a styrene resin, using an extruder, kneader, Banbury mixer, roll, etc. in advance to prepare a masterbatch containing a high concentration of various additives in the styrene resin, and using the masterbatch Examples thereof include a method of mixing the styrene resin with a dry blend, and a method of supplying various additives to the extruder by a supply facility different from the styrene resin. For example, there is a procedure in which various additives are added to a styrene resin and mixed, then supplied to an extruder to be heated and melted, and then a foaming agent is further added and mixed. The timing and kneading time of adding the styrene resin to the styrene resin are not particularly limited.

(1-8. Physical characteristics)
The thermal conductivity of the styrene-based resin extruded foam according to one embodiment of the present invention is not particularly limited, but it is considered that it functions as, for example, a heat insulating material for a building or a heat insulating material for a cold storage or a cold storage vehicle. From the viewpoint of heat insulating properties, the thermal conductivity one week after production measured at an average temperature of 23 ° C. is preferably 0.0244 W / mK or less, more preferably 0.0234 W / mK or less, and 0.0224 W. It is particularly preferable that it is / mK or less.

The apparent density of the styrene resin extruded foam according to the embodiment of the present invention is heat insulating and lightweight considering that it functions as, for example, a heat insulating material for construction, or a heat insulating material for a cold storage or a cold storage vehicle. From the above viewpoint, it is preferably 20 kg / m ³ or more and 60 kg / m ³ or less, and more preferably 25 kg / m ³ or more and 40 kg / m ³ or less.

The closed cell ratio of the styrene resin extruded foam according to the embodiment of the present invention is preferably 90% or more, more preferably 95% or more. When the closed cell ratio is less than 90%, the foaming agent is dissipated from the extruded foam at an early stage, and the heat insulating property is deteriorated.

The average cell diameter in the thickness direction of the styrene resin extruded foam according to the embodiment of the present invention is preferably 0.05 mm or more and 0.5 mm or less, more preferably 0.05 mm or more and 0.4 mm or less, and more preferably 0.05 mm or more. 0.3 mm or less is particularly preferable. In general, the smaller the average cell diameter, the shorter the distance between the bubble walls of the foam, so that the movable range of the bubbles in the extruded foam when giving shape to the extruded foam during extrusion foaming is narrow, and deformation is difficult. Therefore, it tends to be difficult to impart a beautiful surface to the extruded foam and to increase the thickness of the extruded foam. When the average cell diameter in the thickness direction of the styrene resin extruded foam is smaller than 0.05 mm, it tends to be difficult to give the extruded foam a beautiful surface and to obtain the thickness of the extruded foam. It will be something like that. On the other hand, when the average cell diameter in the thickness direction of the styrene resin extruded foam exceeds 0.5 mm, sufficient heat insulating properties may not be obtained.

The average cell diameter of the styrene resin extruded foam according to the embodiment of the present invention was evaluated using a microscope [DIGITAL MICROSCOPE VHX-900 manufactured by KEYENCE Co., Ltd.] as described below.

A total of three width-wise vertical cross sections of the obtained styrene-based resin extruded foam at the center in the width direction and 150 mm from one end in the width direction to the opposite end (the same place for both ends in the width direction). Was observed with the microscope from the extrusion direction and the width direction, and a 100-fold magnified photograph was taken. Three straight lines of 2 mm were arbitrarily drawn in the thickness direction of the enlarged photograph (three at each observation point and each observation direction), and the number a of bubbles in contact with the straight lines was measured. From the measured number of bubbles a, the average bubble diameter A in the thickness direction for each observation point was obtained by the following equation (1). The average value of the three locations (two directions at each location) was taken as the average cell diameter A (average value) in the thickness direction of the styrene resin extruded foam.

Average bubble diameter A (mm) = 2 × 3 / number of bubbles a in the thickness direction for each observation point
... (1).

Extruded vertical cross section of the obtained styrene-based resin extruded foam at three locations in the central portion in the width direction and 150 mm in the opposite end direction from one end in the width direction (the same location for both ends in the width direction). Was observed with the microscope from the width direction, and a 100-fold magnified photograph was taken. Three straight lines of 2 mm were arbitrarily drawn in the extrusion direction of the enlarged photograph (three for each observation point), and the number b of bubbles in contact with the straight lines was measured. From the measured number of bubbles b, the average bubble diameter B in the extrusion direction for each observation point was obtained by the following equation (2). The average value of the three locations was taken as the average cell diameter B (average value) in the extrusion direction of the styrene resin extruded foam.

Average bubble diameter B (mm) in the extrusion direction for each observation point = 2 × 3 / number of bubbles b
... (2).

Width vertical cross section of the obtained styrene resin extruded foam at three locations in the width direction center and 150 mm in the opposite direction from one end in the width direction (same location for both ends in the width direction). Was observed with the microscope from the extrusion direction, and a 100-fold magnified photograph was taken. Three straight lines of 2 mm were arbitrarily drawn in the width direction of the enlarged photograph (three for each observation point), and the number c of bubbles in contact with the straight lines was measured. From the measured number of bubbles c, the average bubble diameter C in the width direction for each observation point was obtained by the following equation (3). The average value of the three locations was taken as the average cell diameter C (average value) in the width direction of the styrene resin extruded foam.

Average bubble diameter C (mm) in the width direction for each observation point = 2 × 3 / number of bubbles c
... (3).

The bubble deformation rate of the styrene resin extruded foam according to one embodiment of the present invention is preferably 0.7 or more and 2.0 or less, more preferably 0.8 or more and 1.5 or less, and 0.8 or more and 1.2. The following is more preferable. When the bubble deformation rate is smaller than 0.7, the compressive strength becomes low, and there is a possibility that the strength suitable for the application cannot be secured in the extruded foam. Further, since the bubbles tend to return to a spherical shape, the dimension (shape) maintainability of the extruded foam tends to be inferior. On the other hand, when the bubble deformation rate exceeds 2.0, the number of bubbles in the thickness direction of the extruded foam is reduced, so that the effect of improving the heat insulating property due to the bubble shape is reduced.

The bubble deformation rate of the styrene resin extruded foam according to the embodiment of the present invention can be obtained from the above-mentioned average bubble diameter by the following formula (4).

Bubble deformation rate (no unit) = A (mean value) / {[B (mean value) + C (mean value)] / 2} ... (4).

The thickness of the styrene resin extruded foam according to the embodiment of the present invention is heat insulating property, bending strength and compressive strength in consideration of functioning as, for example, a heat insulating material for a building or a heat insulating material for a cold storage or a cold storage vehicle. From the above viewpoint, it is preferably 10 mm or more and 150 mm or less, more preferably 20 mm or more and 130 mm or less, and particularly preferably 30 mm or more and 120 mm or less.

In the styrene resin extruded foam, as described in Examples and Comparative Examples of the present invention, after extrusion foam molding is performed to give a shape, both surfaces of a plane perpendicular to the thickness direction are unilaterally sided in the thickness direction. The product may be cut to a depth of about 5 mm to obtain the product thickness, but unless otherwise specified, the thickness of the styrene resin extruded foam according to the embodiment of the present invention is extruded to give a shape. It is the uncut thickness as it is.

The shape of the styrene resin extruded foam according to the embodiment of the present invention is, for example, in the extrusion direction, the width direction, and the thickness so as to be suitably used as a heat insulating material for construction or a heat insulating material for a cold storage or a cold storage vehicle. It should be plate-shaped with no waviness in either direction. As described above, for example, when a hydrofluoroolefin is used, when a heat ray radiation inhibitor is used, or when the average cell diameter becomes finer as a styrene-based extruded foam, the elongation of the resin itself deteriorates. Or, because the movable range of the bubbles of the extruded foam when extruded and foamed to give the shape is narrow and it is difficult to deform, the shape can be given when the extrusion foam molding is performed and the adjustment to the thickness is attempted. However, the extruded foam may not be in the shape of a plate because it is wavy in one or more of the extrusion direction, the width direction, and the thickness direction.

The surface properties of the styrene-based resin extruded foam according to the embodiment of the present invention are intended to ensure stability during manufacturing, and when used as a product while leaving both surfaces of a plane perpendicular to the thickness direction. Since it is particularly important, it needs to be beautiful with no flow marks, cracks, or lumps. As described above, for example, when a hydrofluoroolefin is used, when a heat ray radiation inhibitor is used, or when the average cell diameter becomes finer as a styrene-based extruded foam, the elongation of the resin itself deteriorates. Or, when the extruded foam is extruded to give shape, the movable range of the bubbles of the extruded foam is narrow and it is difficult to deform, so that flow marks, cracks, worms, etc. occur on the surface of the extruded foam. The surface quality may be impaired. A flow mark is a flow mark of a resin melt, and is generated on both surfaces of a plane perpendicular to the thickness direction when the resin itself is hard and does not stretch well. Cracks are cracks that occur when an excessive force is applied to the extruded foam, and are particularly likely to occur when the extruded foam is forcibly molded to increase its thickness while it is difficult to obtain the thickness. .. It may occur on both surfaces of a plane perpendicular to the thickness direction, or it may occur at the edge (side) in the width direction. In severe cases, cracks may be the starting point and the continuously produced extruded foam may be torn. In addition, mushy is a part of the foamed resin melt that solidifies too much and gets caught in the molding die and rolls up, so that both surfaces of the plane perpendicular to the thickness direction and the edges (sides) in the width direction are It may occur locally or globally.

Thus, according to one embodiment of the present invention, it is possible to easily obtain a styrene-based resin extruded foam having excellent heat insulating properties and flame retardancy, having a beautiful appearance, and having a sufficient thickness suitable for use. can.

[2. Method for manufacturing styrene resin extruded foam]
The method for producing a styrene-based resin extruded foam according to an embodiment of the present invention is described in [1. Styrene-based resin extruded foam] is a production method used for producing the styrene-based resin extruded foam. Among the configurations used in the method for producing a styrene resin extruded foam according to an embodiment of the present invention, [1. The configuration already described in [Styrene-based resin extruded foam] will be omitted here.

As a method for producing the styrene resin extruded foam according to the embodiment of the present invention, a styrene resin, a flame retardant, and if necessary, a stabilizer, a heat ray radiation inhibitor, a moldability improver, or other Additives and the like are supplied to the heating and melting part of the extruder and the like. At this time, the foaming agent can be added to the styrene resin under high pressure conditions at any stage. Then, a mixture of a styrene resin, a foaming agent, and other additives is formed as a fluidized gel (in other words, a resin melt), cooled to a temperature suitable for extrusion foaming, and then the fluidized gel is passed through a die to a low pressure region. Extruded and foamed to form a foam.

The heating temperature in the heat-melting portion may be a temperature higher than the temperature at which the styrene-based resin used melts, but the temperature at which molecular deterioration of the resin due to the influence of additives or the like is suppressed as much as possible, for example, 150 ° C. to 260 ° C. The degree is preferable. The melt-kneading time in the heat-melting section is uniquely specified because it differs depending on the extrusion amount of the styrene resin per unit time and / or the type of the extruder used as the heat-melting section and used as the melt-kneading section. This is not possible, and the time required for the styrene resin to be uniformly dispersed and mixed with the foaming agent and the additive is appropriately set.

Examples of the melt-kneaded portion include a screw type extruder, but the melt-kneaded portion is not particularly limited as long as it is used for ordinary extrusion foaming.

The foam molding method according to an embodiment of the present invention is, for example, an extruded foam obtained by opening from a high pressure region to a low pressure region through a slit die having a straight slit shape at an opening used for extrusion molding. A method of forming a plate-shaped foam having a large cross-sectional area by using a molding die installed in close contact with or in contact with a slit die, a forming roll installed adjacent to the downstream side of the forming die, or the like. Is used. By adjusting the flow surface shape and the mold temperature of the molding die, the desired cross-sectional shape of the foam, the surface property of the foam, and the quality of the foam can be obtained.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention. Further, by combining the technical means disclosed in each embodiment, new technical features can be formed.

Hereinafter, examples of the present invention will be described. Needless to say, the present invention is not limited to the following examples.

The raw materials used in the examples and comparative examples are as follows.

○ Base resin / styrene resin [PS Japan Corporation, G9401; MFR 2.2 g / 10 minutes]
○ Heat ray radiation inhibitor ・ Graphite [M-885 manufactured by Marutoyo Casting Co., Ltd.; Scale (piece) graphite, average particle size 5.5 μm, fixed carbon content 89%]
-Titanium oxide [manufactured by Sakai Chemical Industry Co., Ltd., R-7E; average particle size 0.23 μm].

○ Flame Retardant ・ Mixed brominated flame retardant of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether [Daiichi Kogyo Made by Pharmaceutical Co., Ltd., GR-125P].
-Brominated styrene-butadiene block copolymer [EMERALD INNOVATION # 3000, manufactured by Chemtura].

○ Flame-retardant aid, triphenylphosphine oxide [Sumitomo Shoji Chemical].
-Tetrakis (2,6-dimethylphenyl) -m-phenylene bisphosphate [manufactured by Daihachi Kagaku, PX-200]
○ Radical generator ・ Poly-1,4-diisopropylbenzene [manufactured by UNITED INITIOTORS, CCPIB].
○ Stabilizer ・ Bisphenol-A-glycidyl ether [manufactured by ADEKA Corporation, EP-13].
-Cresol novolak type epoxy resin [manufactured by Huntsman Japan, ECN-1280]
-Dipentaerythritol-Adipic acid reaction mixture [Ajinomoto Fine-Techno Co., Ltd., Plenizer ST210]
-Pentaerythritol tetrakis [3- (3', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] [Chemtura, ANOX20]
3,9-bis (2,4-di-tert-butylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] Undecane [Chemtura, Ultranox 626]
-Triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate [Songwon Japan Co., Ltd., Sonnox 2450FF].
○ Other additives
・ Talc [Tarkhan powder PK-Z manufactured by Hayashi Kasei Co., Ltd.]
・ Calcium stearate [SC-P, manufactured by Sakai Chemical Industry Co., Ltd.]
・ Bentonite [Made by Hojun Co., Ltd., Wenger Bright 11K]
・ Silica [Carplex BS-304F, manufactured by Evonik Degussa Japan Co., Ltd.]
-Ethylene bisstearic acid amide [manufactured by NOF CORPORATION, Alflo H-50S].
○ Moldability improver ・ Polyethylene glycol [manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., PEG 6000; average molecular weight 7400 to 9000, freezing point 56 to 61 ° C]
-Stearic acid monoglyceride [manufactured by Riken Vitamin Co., Ltd., Rikemar S-100P, melting point 67 ° C]
○ Foaming agent / Trans-HFO-1234ze [Manufactured by Honeywell Japan Co., Ltd.]
・ Dimethyl ether [manufactured by Iwatani Corp.]
・ Isobutane [manufactured by Mitsui Chemicals, Inc.]
・ Ethyl chloride [manufactured by Nippon Tokushu Kagaku Kogyo Co., Ltd.]
・ Water [Tap water in Settsu City, Osaka Prefecture].

For Examples and Comparative Examples, the thickness of the styrene resin extruded foam (before cutting), the residual amount of HFO-1234ze per 1 kg of the foam, the residual amount of isobutane, the apparent density, the closed cell ratio, the average cell diameter, etc. The bubble deformation rate, thermal conductivity, and JIS flammability were evaluated.

(1) Evaluation of thickness (before cutting) and variation in thickness of styrene resin extruded foam Using a caliper [Mitutoyo Co., Ltd., M-type standard caliper N30], at intervals of 75 mm around the center in the width direction. The thickness of a total of 13 places was measured. The average value of 13 points was taken as the thickness of the styrene resin extruded foam. In addition, the measured values were evaluated according to the following criteria.
◯: The variation in thickness (maximum value-minimum value) is within 10 mm.
X: The variation in thickness (maximum value-minimum value) exceeds 10 mm.

(2) Residual amount of HFO-1234ze and residual amount of isobutane per 1 kg of foam The obtained styrene-based resin extruded foam is subjected to standard temperature state 3 (23 ° C ± 5 ° C) specified in JIS K 7100, and standard humidity. The mixture was allowed to stand under the condition of the third grade (50 ^{+ 20, -10} % RH), and the residual amount of HFO-1234ze and the residual amount of isobutane 7 days after the production were evaluated by the following equipment and procedure.
a) Equipment used; Gas chromatograph GC-2014 [manufactured by Shimadzu Corporation]
b) Column used; G-Column G-950 25UM [manufactured by Chemicals Evaluation and Research Institute]
c) Measurement conditions;
・ Injection port temperature: 65 ° C
-Column temperature: 80 ° C
-Detector temperature: 100 ° C
・ Carry gas: High-purity helium ・ Carry gas flow rate: 30 mL / min ・ Detector: TCD
・ Current: 120mA

A test piece of about 1.2 g is placed in a sealable glass container of about 130 cc (hereinafter referred to as "sealed container"), which varies depending on the apparent density cut out from the foam, and the air inside the closed container is evacuated by a vacuum pump. rice field. Then, the closed container was heated at 170 ° C. for 10 minutes, and the foaming agent in the foam was taken out into the closed container. After the closed container returns to room temperature, helium is introduced into the closed container and returned to atmospheric pressure, and then 40 μL of the mixed gas containing HFO-1234ze and isobutane is taken out with a microsyringe, and the above a) to c) are used. Evaluation was made using equipment and measurement conditions.

(3) Apparent density (kg / m ³ )
The weight of the obtained styrene-based resin extruded foam was measured, and the length, width, and thickness were measured.

From the measured weight and each dimension, the foam density was obtained based on the following formula (5), and the unit was converted to kg / m ³ .
Apparent density (g / cm ³ ) = foam weight (g) / foam volume (cm ³ ) ... (5)

(4) Closed cell ratio The thickness of the obtained styrene resin extruded foam is 40 mm from a total of three locations, 150 mm in the width direction from one end to the opposite end (the same location for both ends in the width direction). Using a test piece cut into a length (extrusion direction) of 25 mm and a width of 25 mm, measurement was performed according to procedure C of ASTM-D2856-70, and the closed cell ratio of each test piece was obtained by the following formula (6). The average value of the three locations was taken as the closed cell ratio of the styrene resin extruded foam.
Closed cell ratio (%) = (V1-W / ρ) × 100 / (V2-W / ρ) ... (6)
Here, V1 (cm ³ ) is the true volume of the test piece (volume of the non-closed cell portion) measured using an air comparative hydrometer [Tokyo Science Co., Ltd., air comparative hydrometer, model 1000 type]. Is excluded.). V2 (cm ³ ) is an apparent volume calculated from the outer dimensions of the test piece measured using a caliper [Mitutoyo Co., Ltd., M-type standard caliper N30]. W (g) is the total weight of the test piece. Further, ρ (g / cm ³ ) is the density of the styrene-based resin constituting the extruded foam, and was set to 1.05 (g / cm ³ ).

(5) Average bubble diameter and bubble deformation rate in the thickness direction The obtained styrene-based resin extruded foam was evaluated as described above.

(6) Thermal conductivity According to JIS A 9521, using a test piece cut into a thickness product thickness x length (extrusion direction) 300 mm x width 300 mm, a thermal conductivity measuring device [Eiko Seiki Co., Ltd., HC- 074] measured the thermal conductivity at an average temperature of 23 ° C. After the styrene resin extruded foam is manufactured, it is cut into test pieces of the above dimensions, and the standard temperature condition 3 (23 ° C ± 5 ° C) and standard humidity 3 (50 ° C) specified in JIS K 7100 are measured. It was allowed to stand under the conditions of ^{+20, -10} % RH), and was carried out 7 days after the production. The thermal conductivity value obtained by the measurement was judged according to the following criteria.
○ (Pass): Thermal conductivity is 0.024 (0.0244) W / mK or less.
× (Failure): Thermal conductivity is greater than 0.024 (0.0244) W / mK.

(7) JIS flammability According to JIS A 9521, a test piece having a thickness of 10 mm, a length of 200 mm and a width of 25 mm was used and evaluated according to the following criteria. After the styrene resin extruded foam is manufactured, it is cut into test pieces of the above dimensions, and the standard temperature condition 3 (23 ° C ± 5 ° C) and standard humidity 3 (50 ° C) specified in JIS K 7100 are measured. It was allowed to stand under the conditions of ^{+20, -10} % RH), and one week after the production.
◯: Satisfies the criteria that the flame is extinguished within 3 seconds, there is no residue, and the combustion does not exceed the combustion limit indicator line.
×: Does not meet the above criteria.

(8) Appearance of foam From the evaluation results of shape and surface properties described in (8) -1 and (8) -2 below, the determination was made according to the following evaluation criteria.
Pass: Both the shape and surface quality evaluation results are ○.
Fail: At least one of the evaluation results of shape and surface property is Δ or ×.

(8) -1. The extruded foam after the shape forming roll and before cutting was visually inspected and evaluated according to the following evaluation criteria.
◯: The extruded foam has a plate shape without waviness in any of the extrusion direction, the width direction, and the thickness direction.
X: The extruded foam is wavy in one or more of the extrusion direction, the width direction, and the thickness direction, and is not plate-shaped.

(8) -2. The extruded foam before and after the surface cut was visually inspected and evaluated according to the following evaluation criteria. The surface refers to a surface perpendicular to the thickness direction, and after cutting, both surfaces are cut at a depth of 5 mm on one side in the thickness direction based on the thickness of the styrene resin extruded foam (3-point average value). Refers to the state.
◯: The surface is beautiful with no surface abnormalities such as flow marks, cracks, and lumps.
Δ: There are surface abnormalities such as flow marks, cracks, and burrs, but these marks do not remain on the surface after cutting.
X: There are surface abnormalities such as flow marks, cracks, and burrs, and these marks remain on the surface after cutting.

For Examples and Comparative Examples, graphite and titanium oxide were added by a masterbatch prepared according to the following method.

[Making a graphite masterbatch]
In a Banbury mixer, 100 parts by weight of styrene resin [PS Japan Co., Ltd., G9401], which is a base resin, and 100 parts by weight of styrene resin A, graphite [manufactured by Marutoyo Casting Co., Ltd., M-885] 102 parts by weight and ethylene bisstearic acid amide [Alflow H-50S manufactured by Nichiyu Co., Ltd.] 2.0 parts by weight are added and heated and cooled under a load of 5 kgf / cm ² . Was melt-kneaded for 20 minutes without performing. At this time, the resin temperature was measured and found to be 190 ° C. A strand-shaped resin supplied to a ruder and extruded at a discharge rate of 250 kg / hr through a die having a small hole attached to the tip was cooled and solidified in a water tank at 30 ° C., and then cut to obtain a masterbatch.

[Making a titanium oxide masterbatch]
In a Banbury mixer, 100 parts by weight of styrene resin A [PS Japan Co., Ltd., G9401], which is a base resin, and 100 parts by weight of styrene resin A, titanium oxide [manufactured by Sakai Chemical Industry Co., Ltd., R-7E] 154 parts by weight and ethylene bisstearic acid amide [Alflow H-50S manufactured by Nichiyu Co., Ltd.] 2.6 parts by weight were added and heated and cooled with a load of 5 kgf / cm ² . Was melt-kneaded for 20 minutes without performing. At this time, the resin temperature was measured and found to be 190 ° C. A strand-shaped resin supplied to a ruder and extruded at a discharge rate of 250 kg / hr through a die having a small hole attached to the tip was cooled and solidified in a water tank at 30 ° C., and then cut to obtain a masterbatch.

(Example 1)
[Preparation of resin mixture]
Tetrabromobisphenol A-bis (2,3-dibromo-) as a flame retardant with respect to 100 parts by weight of the styrene resin [PS Japan Co., Ltd., G9401] which is the base resin and 100 parts by weight of the styrene resin. A mixed brominated flame retardant of 2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether [GR-125P, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.] 3.0 parts by weight , 1.0 part by weight of triphenylphosphine oxide [Sumitomo Shoji Chemical] as a flame retardant auxiliary, 2.01.0 parts by weight of talc [Talcan powder PK-Z manufactured by Hayashi Kasei Co., Ltd.] as a bubble size adjuster, stable As an agent, bisphenol-A-glycidyl ether [manufactured by ADEKA Co., Ltd., EP-13] 0.20 part by weight, triethylene glycol-bis-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate [Songwon Japan Co., Ltd., Sonnox 2450FF] 0.20 parts by weight, dipentaerythritol-adipic acid reaction mixture [Ajinomoto Fine Techno, Plenlyzer ST210] 0.10 parts by weight, calcium stearate as a retardant [Sakai Chemical Industry] 0.20 parts by weight of SC-P manufactured by Co., Ltd., 0.40 parts by weight of bentnite [Hojun Co., Ltd., Bengel Bright 11K] as a water absorbing medium, and silica [Ebonic Degusa Japan Co., Ltd., Carplex BS-304F] 0.40 parts by weight was dry blended.

[Preparation of extruded foam]
Approximately 950 kg / hr to the obtained resin mixture, a single-screw extruder with a diameter of 150 mm (first extruder), a single-screw extruder with a diameter of 200 mm (second extruder), and an extruder in which a cooler is connected in series. Supplied in.

The resin mixture supplied to the first extruder is heated to a resin temperature of 240 ° C. to melt, plasticize, and knead, and a foaming agent (HFO-1234ze 6.0 parts by weight, isobutane 1 with respect to 100 parts by weight of the base resin). (5.5 parts by weight, 1.5 parts by weight of dimethyl ether, and 0.8 parts by weight of water) were press-fitted into the resin near the tip of the first extruder. After that, the resin temperature was cooled to 122 ° C. in the second extruder and the cooler connected to the first extruder, and a base (slit die) having a rectangular cross section with a thickness of 6 mm and a width of 400 mm was provided at the tip of the cooler. ), After extruding and foaming into the atmosphere at a foaming pressure of 4.0 MPa, a molding die installed in close contact with the mouthpiece and a molding roll installed on the downstream side thereof have a cross-sectional shape of 60 mm in thickness and 1000 mm in width. An extruded foam plate was obtained and cut into a thickness of 50 mm, a width of 910 mm and a length of 1820 mm with a cutter. The evaluation results of the obtained foam are shown in Table 1.

(Examples 2 to 11)
As shown in Table 1, an extruded foam was obtained by the same operation as in Example 1 except that the types, addition amounts, and / or production conditions of various formulations were changed. Table 1 shows the physical characteristics of the obtained extruded foam. As described above, graphite and titanium oxide were added in advance in the form of a masterbatch of a styrene-based resin at the time of preparation of the resin mixture. When the masterbatch was used, the base resin was 100 parts by weight in total with the base resin contained in the masterbatch.

(Comparative Examples 1 to 4)
As shown in Table 2, an extruded foam was obtained by the same operation as in Example 1 except that the types, addition amounts, and / or production conditions of various formulations were changed. Table 2 shows the physical characteristics of the obtained extruded foam. As described above, graphite and titanium oxide were added in advance in the form of a masterbatch of a styrene-based resin at the time of preparation of the resin mixture. When the masterbatch was used, the base resin was 100 parts by weight in total with the base resin contained in the masterbatch.

As can be seen from Comparative Example 1, when the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms in the extruded foam 7 days after the production of the styrene resin extruded foam is larger than a predetermined amount, the flammability becomes longer. Deteriorates.

As can be seen from Comparative Example 2, when the residual amount of hydrofluoroolefin in the extruded foam 7 days after the production of the styrene resin extruded foam is less than a predetermined amount, the thermal conductivity exceeds 0.024 W / mK. And get worse.

As in Comparative Example 3, the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms in the extruded foam 7 days after the production of the styrene resin extruded foam, and 7 days after the production of the styrene resin extruded foam. When the total amount of the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the extruded foam is larger than a predetermined amount, or as in Comparative Example 4, styrene resin extruded foaming When the residual amount of hydrofluoroolefin in the extruded foam 7 days after the production of the body is larger than a predetermined amount, the moldability of the extruded foam deteriorates, the moldability of the extruded foam deteriorates, and the desired foaming occurs. Extruded foam having a body appearance cannot be obtained.

As can be seen from Examples 1 to 6, the styrene-based resin extruded foam of the present invention has an excellent heat insulating property and excellent flame retardancy with a thermal conductivity of 0.024 W / mK or less, and further has a surface surface. It can be seen that it is a styrene-based resin extruded foam that is beautiful and has a sufficient thickness suitable for use.

Since the present invention is a styrene-based resin extruded foam having excellent heat insulating properties and flame-retardant properties, a beautiful surface, and a sufficient thickness suitable for use, the styrene-based resin is used. The resin extruded foam can be suitably used as a heat insulating material for a house or a structure.

Claims (9)

A styrene resin extruded foam containing a flame retardant of 0.5 parts by weight or more and 8.0 parts by weight or less with respect to 100 parts by weight of the styrene resin.
It contains saturated hydrocarbons with 3 to 5 carbon atoms and hydrofluoroolefins as foaming agents.
(I) The residual amount of hydrofluoroolefin in the extruded styrene resin foam is 0.48 mol or more and 0.80 mol or less per 1 kg of the extruded foam.
(II) The residual amount of saturated hydrocarbons having 3 to 5 carbon atoms in the styrene-based resin extruded foam is 0.05 mol or more and 0.35 mol or less per 1 kg of the extruded foam.
(III) The total amount of the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the styrene-based resin extruded foam is 0.46 mol or more and 0.90 mol or less per 1 kg of the extruded foam. Styrene-based resin extruded foam, characterized by being:
Here, the residual amount of the hydrofluoroolefin and the residual amount of the saturated hydrocarbon having 3 to 5 carbon atoms are determined.
The styrene resin extruded foam is statically subjected to the conditions of the standard temperature state 3 (23 ° C ± 5 ° C) and the standard humidity 3 (50 + 20, -10% RH) specified in JIS K 7100. Placed and evaluated 7 days after manufacture with the following equipment and procedures:
a) Equipment used; gas chromatograph
b) Column used; G-Column
c) Measurement conditions;
・ Injection port temperature: 65 ° C
-Column temperature: 80 ° C
-Detector temperature: 100 ° C
・ Carry gas: High-purity helium
・ Carry gas flow rate: 30 mL / min
-Detector: TCD
・ Current: 120mA
d) Measurement procedure;
A test piece cut out from the styrene resin extruded foam is placed in a sealable glass container, the glass container is evacuated by a vacuum pump, and then the glass container is heated at 170 ° C. for 10 minutes. The foaming agent in the glass container is taken out into the glass container, the temperature of the glass container is returned to room temperature, helium is introduced into the glass container and the pressure is returned to atmospheric pressure, and then 40 μL of the foaming agent is contained in the glass container. The mixed gas was taken out and evaluated under the equipment used and the measurement conditions of a) to c) above. A styrene resin extruded foam containing a flame retardant of 0.5 parts by weight or more and 8.0 parts by weight or less with respect to 100 parts by weight of the styrene resin.
It contains saturated hydrocarbons with 3 to 5 carbon atoms and hydrofluoroolefins as foaming agents.
(I) The residual amount of hydrofluoroolefin in the extruded styrene resin foam is 0.41 mol or more and 0.80 mol or less per 1 kg of the extruded foam.
(II) The residual amount of saturated hydrocarbons having 3 to 5 carbon atoms in the styrene-based resin extruded foam is 0.05 mol or more and 0.21 mol or less per 1 kg of the extruded foam.
(III) The total amount of the residual amount of saturated hydrocarbons having 3 to 5 carbon atoms and the residual amount of hydrofluoroolefin in the styrene-based resin extruded foam is 0.46 mol or more and 0.90 mol or less per 1 kg of the extruded foam. Styrene-based resin extruded foam, characterized by being:
Here, the residual amount of the hydrofluoroolefin and the residual amount of the saturated hydrocarbon having 3 to 5 carbon atoms are determined.
The styrene resin extruded foam is statically subjected to the conditions of the standard temperature state 3 (23 ° C ± 5 ° C) and the standard humidity 3 (50 + 20, -10% RH) specified in JIS K 7100. Placed and evaluated 7 days after manufacture with the following equipment and procedures:
a) Equipment used; gas chromatograph
b) Column used; G-Column
c) Measurement conditions;
・ Injection port temperature: 65 ° C
-Column temperature: 80 ° C
-Detector temperature: 100 ° C
・ Carry gas: High-purity helium
・ Carry gas flow rate: 30 mL / min
-Detector: TCD
・ Current: 120mA
d) Measurement procedure;
A test piece cut out from the styrene resin extruded foam is placed in a sealable glass container, the glass container is evacuated by a vacuum pump, and then the glass container is heated at 170 ° C. for 10 minutes. The foaming agent in the glass container is taken out into the glass container, the temperature of the glass container is returned to room temperature, helium is introduced into the glass container and the pressure is returned to atmospheric pressure, and then 40 μL of the foaming agent is contained in the glass container. The mixed gas was taken out and evaluated under the equipment used and the measurement conditions of a) to c) above. The styrene-based resin extruded foam according to claim 1 or 2 , which contains graphite in an amount of 1.0 part by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the styrene-based resin. 3. The styrene-based resin extruded foam according to item 1 . The styrene-based resin extruded foam according to any one of claims 1 to 4 , wherein at least one of the saturated hydrocarbons having 3 to 5 carbon atoms is isobutane. The styrene-based resin extruded foam according to any one of claims 1 to 5 , wherein the hydrofluoroolefin is tetrafluoropropene. The styrene-based resin extruded foam according to any one of claims 1 to 6 , wherein the thickness is 10 mm or more and 150 mm or less. The styrene-based resin extruded foam according to any one of claims 1 to 7 , wherein the apparent density is 20 kg / m ³ or more and 60 kg / m ³ or less, and the closed cell ratio is 90% or more. The styrene-based resin extruded foam according to any one of claims 1 to 8 , which contains 0.5 parts by weight or more and 5.0 parts by weight or less of a styrene-based flame retardant with respect to 100 parts by weight of the styrene-based resin.