Styrene-based resin extruded foam and method for producing the same

Abstract

To easily provide a styrenic resin extrusion foam having an excellent heat insulation property and a thickness adjustment property.SOLUTION: A styrenic resin extrusion foam containing a styrenic resin and a foaming agent contains 20-80 wt.% of a styrene-(meth)acrylic acid-based copolymer in 100 wt.% of the styrenic resin, and contains hydro(chloro)fluoroolefin and alkyl chloride as the foaming agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a styrene-based resin extruded foam and a method for producing the same. [Background technology]

[0002] Styrene resin extruded foams are generally manufactured continuously by heating and melting a styrene resin composition using an extruder, then adding a foaming agent under high pressure conditions, cooling to a predetermined resin temperature, and then extruding it into a low-pressure range.

[0003] Styrene-based extruded foams are used as insulation materials for structures, for example, due to their good workability and thermal insulation properties. In recent years, with the increasing demand for energy conservation in houses and buildings, there is a need for technological development of foams with even higher thermal insulation properties than conventional ones.

[0004] As methods for producing highly insulating foams, there are proposed methods that involve adding graphite or titanium dioxide within a predetermined range as a heat radiation suppressant (see, for example, Patent Document 1), and methods for producing styrene resin extruded foams that use environmentally friendly fluorinated olefins (hydrofluoroolefins and hydrochlorofluoroolefins) or alkyl chlorides such as methyl chloride and ethyl chloride as blowing agents, which have an ozone depletion potential of 0 (zero) and a low global warming potential (see, for example, Patent Documents 2 to 4). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-221110 [Patent Document 2] Special Publication No. 2008-546892 [Patent Document 3] Japanese Patent Publication No. 2019-189811 [Patent Document 4] Japanese Patent Publication No. 2019-108416 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, in the styrene resin extruded foam described in the above patent document, while heat radiation suppressants such as graphite and blowing agents such as hydrofluoroolefins can impart excellent heat insulation properties to the foam, there is a challenge in that they have a strong nucleating effect, making it difficult to refine the bubbles and achieve sufficient thickness in the foam.

[0007] Therefore, the object of the present invention is to provide a styrene-based resin extruded foam having excellent heat insulation properties and thickness-forming properties. [Means for solving the problem]

[0008] To solve the above problems, the inventors conducted diligent research and discovered that by combining a specific styrene-based resin and a specific foaming agent, it is possible to achieve both excellent heat insulation and excellent thickness-forming properties, which were not achievable with conventional technology, thus completing the present invention. The present invention includes the following embodiments.

[0009] <1> A styrene resin extruded foam comprising a styrene resin and a blowing agent, The styrene-based resin comprises a styrene-(meth)acrylic acid copolymer. The content of the styrene-(meth)acrylic acid copolymer in 100% by weight of the styrene-based resin is 20 to 80% by weight. The foaming agent comprises hydro(chloro)fluoroolefin and alkyl chloride. Styrene-based resin extruded foam. <2> The styrene-(meth)acrylic acid copolymer has a composition in which (meth)acrylic acid-derived constituent units account for 5 to 20% by weight relative to 100% by weight of all constituent units. <1> Styrene resin extruded foam as described above. <3> The hydro(chloro)fluoroolefin content is 0.10 to 1.0 mol per 1 kg of the styrene resin extruded foam. <1> ~ <2> A styrene-based resin extruded foam as described in any one of the items. <4> The alkyl chloride content is 0.10 to 1.0 mol per 1 kg of the styrene resin extruded foam. <1> ~ <3> A styrene-based resin extruded foam as described in any one of the items. <5> The styrene-based resin extruded foam contains graphite in an amount of 1.0 part by weight or more and 5.0 parts by weight or less per 100 parts by weight of styrene-based resin. <1> ~ <4> A styrene-based resin extruded foam as described in any one of the items. <6> The thermal conductivity of the styrene resin extruded foam is 0.0224 W / mK or less. <1> ~ <5> A styrene-based resin extruded foam as described in any one of the items. <7> The apparent density of the styrene resin extruded foam is 20-60 kg / m³ 3 That is, <1> ~ <6> A styrene-based resin extruded foam as described in any one of the items. <8> The thickness of the styrene resin extruded foam is 10 mm or more and 150 mm or less. <1> ~ <7> A styrene-based resin extruded foam as described in any one of the items. <9> A method for producing an extruded styrene resin foam by extruding a foamable styrene resin composition obtained by melt-kneading a styrene resin and a foaming agent, wherein the method satisfies the following conditions (a) to (c): (a) The styrene-based resin comprises a styrene-(meth)acrylic acid copolymer, (b) The content of the styrene-(meth)acrylic acid copolymer in 100% by weight of the styrene resin is 20 to 80% by weight, (c) The foaming agent comprises hydro(chloro)fluoroolefin, alkyl chloride, and water. <10> The aforementioned foaming agent is, in proportion to 100 parts by weight of styrene resin, (c1) The amount of hydro(chloro)fluoroolefin added is 3 to 10 parts by weight, (c2) The amount of alkyl chloride added is 2 to 6 parts by weight, (c3) The amount of water added is 0.3 to 1.5 parts by weight, The method for producing a styrene resin extrusion foam according to <9>.

Effect of the Invention

[0010] According to the present invention, a styrene resin extrusion foam that achieves both excellent heat insulation and thickness build-up properties can be obtained.

Mode for Carrying Out the Invention

[0011] 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 each configuration described below, and various modifications are possible within the scope shown in the claims. Embodiments and examples obtained by appropriately combining the technical means disclosed in different embodiments and examples are also included in the technical scope of the present invention. In addition, all academic documents and patent documents described in this specification are incorporated herein by reference. Further, unless otherwise specified in this specification, "A~B" representing a numerical range is intended to mean "A or more and B or less".

[0012] Styrene-(meth)acrylic acid copolymers are generally used for the purpose of imparting heat resistance and chemical resistance because they are superior in heat resistance and chemical resistance to polystyrene. However, since they have properties similar to those of polystyrene, it is difficult to assume that they have a particularly excellent effect of improving thickness build-up properties. When hydro(chloro)fluoroolefin is used as a foaming agent for a polystyrene resin, the bubbles of the styrene resin extrusion foam tend to be refined, and the thickness build-up property of the styrene resin extrusion foam tends to be impaired. However, by using a foaming agent containing at least two types of styrene resins, one of which contains a styrene-(meth)acrylic acid copolymer, and containing hydro(chloro)fluoroolefin and alkyl chloride, excellent heat insulation can be achieved, and excellent thickness build-up properties can also be achieved. Note that "(meth)acrylic" means "methacrylic and / or acrylic".

[0013] Embodiments of the present invention will be described below.

[0014] [1. Styrene-based resin extruded foam] The styrene resin extruded foam according to one embodiment of the present invention is characterized in that the styrene resin contains a specific amount of a styrene-(meth)acrylic acid copolymer, and the foaming agent contains hydro(chloro)fluoroolefin and alkyl chloride.

[0015] (1-1. Styrene resins) The styrene resin extruded foam in one embodiment of the present invention comprises a styrene resin, which consists of a blend of at least two types of polymers, one of which is a styrene-(meth)acrylic copolymer. That is, the styrene resin comprises (i) a styrene-(meth)acrylic acid copolymer and (ii) a styrene polymer other than (i) (hereinafter referred to as "other styrene polymers"). Here, (ii) other styrene polymers include, for example, a homopolymer of styrene monomers (polystyrene), a copolymer of two or more styrene monomers, or a copolymer of a styrene monomer and another monomer.

[0016] Examples of styrene monomers constituting (i) styrene-(meth)acrylic acid copolymers and (ii) other styrene polymers include styrene, methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, vinyltoluene, vinylxylene, and the like.

[0017] Examples of monomers other than styrene monomers and (meth)acrylic acid include polyfunctional vinyl compounds such as divinylbenzene; (meth)acrylic acid ester compounds such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, and butyl methacrylate; acrylonitrile; diene compounds such as butadiene; unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride; and N-alkyl-substituted maleimide compounds such as N-methylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(2)-chlorophenylmaleimide, N-(4)-bromophenylmaleimide, and N-(1)-naphthylmaleimide. (i) Styrene-(meth)acrylic acid copolymers may also contain these other monomers as constituent units.

[0018] The amount of styrene monomers contained in the other styrene polymer is preferably 80 to 100% by weight, and more preferably 90 to 100% by weight, relative to 100% by weight of the constituent units of the other styrene polymer.

[0019] The total amount of styrene monomers and (meth)acrylic acid contained in the styrene-(meth)acrylic acid copolymer is preferably 80 to 100% by weight, and more preferably 90 to 100% by weight, based on 100% by weight of the constituent units of the styrene-(meth)acrylic acid copolymer.

[0020] (i) The styrene-(meth)acrylic acid copolymer and (ii) the other styrene-based polymer may each be a single polymer or a combination of two or more polymers.

[0021] For the purpose of adjusting the MFR, melt viscosity during molding, melt tension, etc. of the styrene resin used in one embodiment of the present invention, (i) styrene-(meth)acrylic acid copolymer and / or (ii) other styrene polymers may have a branched structure. These may be used individually, or two or more different copolymer components, molecular weight and molecular weight distribution, branched structure, and / or MFR may be mixed and used.

[0022] In one embodiment of the present invention, (i) the content of the styrene-(meth)acrylic acid copolymer is 20% by weight or more and 80% by weight of 100% by weight of the styrene resin. From the viewpoint of easily improving the thickness-forming effect of the styrene resin extruded foam, 22% by weight or more and 78% by weight or less is preferred, 25% by weight or more and 75% by weight or less is more preferred, 30% by weight or more and 70% by weight or less is even more preferred, 35% by weight or more and 65% by weight or less is particularly preferred, 40% by weight or more and 60% by weight or less is even more preferred, and 45% by weight or more and 55% by weight or less is most preferred.

[0023] In one embodiment of the present invention, the constituent units derived from (meth)acrylic acid contained in the (i) styrene-(meth)acrylic acid copolymer are preferably 5 to 20% by weight, more preferably 5 to 17% by weight, and even more preferably 5 to 15% by weight, per 100% by weight of the (i) styrene-(meth)acrylic acid copolymer. If the (meth)acrylic acid component contained in the (i) styrene-(meth)acrylic acid copolymer is less than 5% by weight, the amount of (meth)acrylic acid component is too small, and the thickness-building effect may not be achieved. On the other hand, if the amount of (meth)acrylic acid component is more than 20% by weight, the amount of (meth)acrylic acid component is too large, which may result in poor elongation during foaming and inhibit foaming.

[0024] In one embodiment of the present invention, a styrene resin MFR of 0.1 to 50 g / 10 min is preferable because (i) it offers excellent moldability during extrusion foam molding, (ii) it allows for easy adjustment of the discharge amount during molding, the thickness, width, apparent density, and closed-cell ratio of the obtained styrene resin extruded foam to desired values, (iii) it offers excellent foamability (ease of adjusting the thickness, width, apparent density, closed-cell ratio, and surface properties of the foam to desired conditions), (iv) it yields a styrene resin extruded foam with excellent appearance, and (v) it yields a styrene resin extruded foam with a balanced set of properties (e.g., mechanical strength such as compressive strength, flexural strength, or bending deflection, and toughness). Furthermore, a styrene resin MFR of 0.3 to 30 g / 10 min is even more preferable, and 0.5 to 25 g / 10 min is particularly preferable, from the viewpoint of balancing moldability and foamability with mechanical strength and toughness. In one embodiment of the present invention, the MFR is measured according to Method A of JIS K7210-1 (2014) and test condition H (test temperature 200°C, load 5 kg).

[0025] (1-2. Foaming agent) The styrene resin extruded foam in one embodiment of the present invention contains hydro(chloro)fluoroolefin and alkyl chloride as blowing agents. This improves the thermal insulation properties of the styrene resin extruded foam. Note that "hydro(chloro)fluoroolefin" means "hydrofluoroolefin and / or hydrochlorofluoroolefin".

[0026] There are no particular restrictions on the hydrofluoroolefin used in one embodiment of the present invention, but tetrafluoropropene and hexafluorobutene are preferred from the viewpoint of low gaseous thermal conductivity and safety. Specifically, examples include trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze), cis-1,3,3,3-tetrafluoropropene (cis-HFO-1234ze), 2,3,3,3-tetrafluoropropene (trans-HFO-1234yf), and cis-1,1,1,4,4,4-hexafluoro-2-butene (cis-HFO-1336mzz). Furthermore, there are no particular restrictions on the hydrochlorofluoroolefin used in one embodiment of the present invention, but hydrochlorotrifluoropropene is preferred from the viewpoint of low gaseous thermal conductivity and safety. Specifically, examples include trans-1-chloro-3,3,3-trifluoropropene (trans-HCFO-1233zd). These hydrofluoroolefins and hydrochlorofluoroolefins may be used individually or in combination of two or more.

[0027] In one embodiment of the present invention, the hydro(chloro)fluoroolefin content is preferably 0.10 to 1.0 mol per 1 kg of styrene resin extruded foam, more preferably 0.15 to 0.8 mol, and even more preferably 0.2 to 0.6 mol. When the hydro(chloro)fluoroolefin content is less than 0.10 mol per 1 kg of styrene resin, the effect of improving thermal insulation by hydro(chloro)fluoroolefin tends not to be very significant. On the other hand, when the hydro(chloro)fluoroolefin content exceeds 1.0 mol per 1 kg of styrene resin extruded foam, the hydro(chloro)fluoroolefin may separate from the resin molten material during extrusion foaming, potentially causing spot holes (traces where localized clumps of hydro(chloro)fluoroolefin have broken through the surface of the extruded foam and been released into the outside air) on the surface of the extruded foam, or reducing the closed-cell ratio and impairing thermal insulation.

[0028] In one embodiment of the present invention, alkyl chlorides having 1 to 3 carbon atoms are preferred, such as ethyl chloride and methyl chloride. One type may be used, or two or more types may be used in combination.

[0029] In one embodiment of the present invention, the alkyl chloride content is preferably 0.10 to 1.0 mol per 1 kg of styrene resin extruded foam, more preferably 0.15 to 0.8 mol, and even more preferably 0.2 to 0.7 mol. If the alkyl chloride content is less than 0.10 mol per 1 kg of styrene resin extruded foam, the effect of improving the heat insulation properties due to alkyl chloride cannot be expected to be significant. On the other hand, if the amount of alkyl chloride added exceeds 1.0 mol per 1 kg of styrene resin extruded foam, the alkyl chloride greatly plasticizes the styrene resin, which may worsen the heat resistance of the resulting styrene resin extruded foam.

[0030] The styrene resin extruded foam of one embodiment of the present invention may contain other foaming agents from the viewpoint of obtaining a plasticizing effect and / or a co-foaming effect during foam production, reducing the extrusion pressure, and enabling stable foam production. Examples include saturated hydrocarbons having 3 to 5 carbon atoms, ethers, ketones, saturated alcohols having 1 to 4 carbon atoms, carboxylic acid esters, water, and carbon dioxide.

[0031] Examples of saturated hydrocarbons having 3 to 5 carbon atoms include propane, n-butane, i-butane, n-pentane, i-pentane, and neopentane. Among these saturated hydrocarbons having 3 to 5 carbon atoms, propane, n-butane, i-butane, or mixtures thereof are preferred from the viewpoint of foaming properties. Furthermore, from the viewpoint of thermal insulation of styrene resin extruded foams, n-butane, i-butane, or mixtures thereof are preferred, with i-butane being particularly preferred. i-butane will also be referred to as "isobutane" below.

[0032] In one embodiment of the present invention, the content of saturated hydrocarbons having 3 to 5 carbon atoms is preferably 0 to 0.5 mol, more preferably 0 to 0.3 mol, and even more preferably 0 to 0.2 mol per 1 kg of styrene resin extruded foam.

[0033] Other blowing 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, and tetrahydropyran; ketones such as dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, methyl-i-butyl ketone, methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-propyl ketone, and ethyl-n-butyl ketone; saturated alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, and t-butyl alcohol; and carboxylic acid esters such as methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate, and ethyl propionate; as well as other organic blowing agents. Inorganic blowing agents such as water and carbon dioxide can also be used. These other foaming agents may be used individually or in combination of two or more.

[0034] Among other blowing agents, saturated hydrocarbons with 3 to 5 carbon atoms, saturated alcohols with 1 to 4 carbon atoms, dimethyl ether, diethyl ether, and methyl ethyl ether are preferred from the viewpoint of foaming properties and foam moldability. Carbon dioxide is preferred from the viewpoint of flammability of the blowing agent, flame retardancy of the foam, or heat insulation properties. Among these, dimethyl ether is particularly preferred from the viewpoint of plasticizing effect.

[0035] (1-3. Flame retardants) In one embodiment of the present invention, flame retardancy can be imparted to the styrene resin extruded foam by adding a flame retardant.

[0036] As the flame retardant, brominated flame retardants are preferably used. Specific examples of brominated flame retardants in one embodiment of the present invention include hexabromocyclododecane, tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl) ether, tetrabromobisphenol A-bis(2,3-dibromopropyl) ether, tris(2,3-dibromopropyl) isocyanurate, and aliphatic bromine-containing polymers such as brominated styrene-butadiene block copolymer. These may be used individually or in combination of two or more.

[0037] Of these, tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl) ether, a mixed brominated flame retardant consisting of tetrabromobisphenol A-bis(2,3-dibromopropyl) ether, brominated styrene-butadiene block copolymer, and hexabromocyclododecane are preferably used because they allow for good extrusion operation and do not adversely affect the heat resistance of the foam. These substances may be used individually or as mixtures.

[0038] In one embodiment of the present invention, the content of the brominated flame retardant in the styrene resin extruded foam is preferably 1.0 part by weight or more and 8.0 parts by weight or less, more preferably 1.5 parts by weight or more and 7.0 parts by weight or less, and even more preferably 2.0 parts by weight or more and 6.0 parts by weight or less, per 100 parts by weight of styrene resin. If the content of the brominated flame retardant is less than 1.0 part 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, it may impair the stability and surface properties during foam manufacturing. However, it is more preferable that the content of the flame retardant be appropriately adjusted according to the amount of foaming agent added, the apparent density of the foam, and the type or content of additives that have a flame retardant synergistic effect, so as to obtain the flame retardancy specified in JIS A 9521 Measurement Method A.

[0039] In one embodiment of the present invention, a radical generator can be used in combination to improve the flame retardant performance of the styrene resin extruded foam. Specifically, examples of the radical generator include 2,3-dimethyl-2,3-diphenylbutane, poly-1,4-diisopropylbenzene, 2,3-diethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3,4-diethyl-3,4-diphenylhexane, 2,4-diphenyl-4-methyl-1-pentene, and 2,4-diphenyl-4-ethyl-1-pentene. Peroxides such as dicumyl peroxide can also be used. Among these, those that are stable under resin processing temperature conditions are preferred, and specifically, 2,3-dimethyl-2,3-diphenylbutane and poly-1,4-diisopropylbenzene are preferred, and the preferred amount of the radical generator to be added is 0.05 to 0.5 parts by weight per 100 parts by weight of styrene resin.

[0040] Furthermore, to improve flame retardancy, or in other words, as a flame retardant additive, phosphorus-based flame retardants such as phosphate esters and phosphine oxides can be used in combination, to the extent that they do not impair thermal stability. Examples of phosphate esters include triphenyl phosphate, tris(tributylbromoneopentyl) phosphate, tricresyl phosphate, trixyllenyl phosphate, cresyldiphenyl phosphate, 2-ethylhexyldiphenyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris(2-ethylhexyl) phosphate, tris(butoxyethyl) phosphate, or condensed phosphate esters, with triphenyl phosphate or tris(tributylbromoneopentyl) phosphate being particularly preferred. In addition, triphenylphosphine oxide is preferred as a phosphine oxide type phosphorus-based flame retardant. These phosphate esters and phosphine oxides may be used individually or in combination of two or more. The preferred amount of phosphorus-based flame retardant to add is 0.1 to 2 parts by weight per 100 parts by weight of styrene resin.

[0041] (1-4. Stabilizers) In one embodiment of the present invention, a flame retardant stabilizer can be used. Specific examples of stabilizers, though not particularly limited, include: (i) epoxy compounds such as bisphenol A diglycidyl ether type epoxy resin, cresol novolac type epoxy resin, and phenol novolac type epoxy resin; (ii) polyhydric alcohol esters which are reaction products of polyhydric alcohols such as pentaerythritol, dipentaerythritol, and tripentaerythritol with monohydric carboxylic acids such as acetic acid and propionic acid, or dihydric carboxylic acids such as adipic acid and glutamic acid, and which are mixtures of esters having one or more hydroxyl groups in their molecules, and which may contain a small amount of the starting polyhydric alcohol; (iii) triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, pentaerythritol tetrakis[3-( Phenolic stabilizers such as 3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and phosphite stabilizers such as (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-3,9-diphosphaspiro[5.5]undecane, and tetrakis(2,4-di-tert-butyl-5-methylphenyl)-4,4'-biphenylenediphosphonite) are preferably used because they improve the thermal stability of the foam without reducing its flame retardancy. These stabilizers may be used individually or in combination of two or more. The preferred amount of stabilizer to add is 0.1 to 2 parts by weight per 100 parts by weight of styrene resin.

[0042] (1-5. Heat radiation suppressants) The styrene resin extruded foam according to one embodiment of the present invention may have a heat radiation suppressant added to improve its heat insulation properties. In one embodiment of the present invention, graphite and carbon black can be used as the heat radiation suppressant. Examples of graphite include flaky graphite, clay graphite, spheroidal graphite, and artificial graphite. Among these, it is preferable to use flaky graphite as the main component because it has a high heat radiation suppression effect. The graphite has a fixed carbon content of 80% or more, and more preferably 85% or more. By setting the fixed carbon content within the above range, a foam with high heat insulation properties can be obtained.

[0043] The average particle size of the graphite is preferably 15 μm or less, and more preferably 10 μm or less. By setting the average particle size within the above range, the specific surface area of ​​the graphite increases, and the probability of collision with thermal radiation increases, thus enhancing the thermal radiation suppression effect. The average particle size refers to the particle size at which the cumulative volume relative to the total volume becomes 50% (volume-averaged particle size by laser diffraction scattering method), which is determined by measuring and analyzing the particle size distribution using a laser diffraction scattering method based on Mie theory in accordance with ISO 13320:2009 and JIS Z8825:2013.

[0044] In one embodiment of the present invention, the graphite content is preferably 0.5 parts by weight or more and 5.0 parts by weight or less per 100 parts by weight of styrene resin, and more preferably 1.0 part by weight or more and 3.0 parts by weight or less. If the content is less than 0.5 parts by weight, a sufficient heat radiation suppression effect cannot be obtained. If the content exceeds 5.0 parts by weight, a heat radiation suppression effect commensurate with the content cannot be obtained, and there is no cost benefit.

[0045] The aforementioned heat radiation suppressor refers to a substance having the properties of reflecting, scattering, and absorbing light in the near-infrared or infrared region. By containing a heat radiation suppressor, a foam with high thermal insulation properties can be obtained. In addition to graphite, white particles such as titanium dioxide, barium sulfate, zinc oxide, aluminum oxide, and antimony oxide can be used as heat radiation suppressors in the present invention. These may be used individually or in combination of two or more. Among the white particles, titanium dioxide or barium sulfate are preferred, and titanium dioxide is more preferred, due to their large heat radiation suppression effect. The average particle size of the white particles is not particularly limited, but considering effective reflection of infrared rays and color development on the resin, for example, 0.1 μm to 10 μm is preferred for titanium dioxide, and 0.15 μm to 5 μm is more preferred.

[0046] In one embodiment of the present invention, the content of white particles is preferably 1.0 part by weight or more and 3.0 parts by weight or less, and more preferably 1.5 parts by weight or more and 2.5 parts by weight or less, per 100 parts by weight of styrene resin. Compared to graphite, white particles have a smaller heat radiation suppression effect, and if the content of white particles is less than 1.0 part by weight, the heat radiation suppression effect is almost negligible even if the white particles are included. If the content of white particles exceeds 3.0 parts by weight, a heat radiation suppression effect commensurate with the content cannot be obtained, while the flame retardancy of the foam tends to deteriorate.

[0047] In one embodiment of the present invention, the total content of the heat radiation inhibitor is preferably 1.0 part by weight or more and 6.0 parts by weight or less, and more preferably 2.0 parts by weight or more and 5.0 parts by weight or less, per 100 parts by weight of the styrene resin. If the total content of the heat radiation inhibitor is less than 1.0 part by weight, it is difficult to obtain heat insulation. On the other hand, as the content of solid additives such as the heat radiation inhibitor increases, the number of nucleation points increases, which tends to make the bubbles in the foam finer and worsen the elongation of the resin itself, making it difficult to impart a beautiful surface to the extruded foam and to achieve the desired thickness. However, if the total content of the heat radiation inhibitor exceeds 6.0 parts by weight, it tends to be particularly difficult to impart a beautiful surface to the extruded foam and to achieve the desired thickness, and furthermore, it tends to impair extrusion stability and flame retardancy.

[0048] (1-6. Other additives) In one embodiment of the present invention, the styrene resin may further contain, if necessary, inorganic compounds such as silica, calcium silicate, wollastonite, kaolin, clay, mica, and calcium carbonate; processing aids such as sodium stearate, calcium stearate, magnesium stearate, barium stearate, liquid paraffin, olefin waxes, and stearylamide compounds; phenolic antioxidants, phosphorus stabilizers, nitrogen stabilizers, sulfur stabilizers, light-resistant stabilizers such as benzotriazoles and hindered amines; bubble size adjusters such as talc; other flame retardants, antistatic agents, colorants such as pigments, and plasticizers, to the extent that they do not impede the effects of one embodiment of the present invention. The preferred amount of other additives is 0 to 2 parts by weight per 100 parts by weight of styrene resin.

[0049] (1-7. Physical Properties) The thermal conductivity of the styrene resin extruded foam according to one embodiment of the present invention is not particularly limited, but from the viewpoint of thermal insulation, considering its function as, for example, a building insulation material or an insulation material for a cold storage or refrigerated vehicle, it is preferable that the thermal conductivity measured at an average temperature of 23°C one week after manufacturing is 0.0284 W / mK or less, more preferably 0.0244 W / mK or less, and particularly preferably 0.0224 W / mK or less.

[0050] The apparent density of the styrene resin extruded foam according to one embodiment of the present invention is 20 kg / m³, from the viewpoint of thermal insulation and lightweight properties, considering its function as, for example, a building insulation material or an insulation material for a cold storage or refrigerated vehicle. 3 More than 60kg / m 3 The following is preferable, and more preferably, 25 kg / m 3 More than 40kg / m 3 The following applies:

[0051] The closed-cell ratio of the styrene resin extruded foam according to one embodiment of the present invention is preferably 90% or more, and more preferably 95% or more. If the closed-cell ratio is less than 90%, the blowing agent dissipates from the extruded foam prematurely, and the thermal insulation performance decreases.

[0052] The average cell diameter in the thickness direction of the styrene resin extruded foam according to one 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 particularly preferably 0.05 mm or more and 0.3 mm or less. Generally, the smaller the average cell diameter, the shorter the distance between the cell walls of the foam, so the range of motion of the cells in the extruded foam when shaping the extruded foam is narrower, making deformation difficult, and making it difficult to give the extruded foam a beautiful surface and to achieve the desired thickness. When the average cell diameter in the thickness direction of the styrene resin extruded foam is less than 0.05 mm, the tendency to make it particularly difficult to give the extruded foam a beautiful surface and to achieve the desired thickness becomes even more pronounced. On the other hand, when the average cell diameter in the thickness direction of the styrene resin extruded foam exceeds 0.5 mm, there is a risk that sufficient heat insulation cannot be obtained.

[0053] Furthermore, the average bubble diameter of the styrene resin extruded foam according to one embodiment of the present invention can be evaluated using a microscope [(KEYENCE Corporation, DIGITAL MICROSCOPE VHX-900)] as described below.

[0054] The vertical cross-sections in the width direction of the obtained styrene resin extruded foam were observed from the extrusion direction using the microscope at three locations: the center in the width direction and 150 mm from one end to the opposite end in the width direction (the same location at both ends in the width direction). 100x magnified photographs were taken. Similarly, the vertical cross-sections in the extrusion direction of the three locations in the width direction were observed from the width direction using the microscope, and 100x magnified photographs were taken. Three 2 mm straight lines were drawn arbitrarily in the thickness direction of the magnified photographs (three lines for each observation location and each observation direction), and the number of bubbles tangent to these lines, a, was measured. From the measured number of bubbles a, the average bubble diameter A in the thickness direction for each observation location was calculated using the following formula (1). The average value of the three locations (two directions for each location) was taken as the average bubble diameter A (average value) in the thickness direction of the styrene resin extruded foam.

[0055] The average bubble diameter A (mm) in the thickness direction for each observation point = 2 × 3 / number of bubbles a ...(1).

[0056] The vertical cross-sections perpendicular to the extrusion direction at three locations in the thickness direction of the obtained styrene resin extruded foam—the center in the width direction and 150 mm from one end to the opposite end in the width direction (the same location at both ends in the width direction)—were observed from the width direction using the aforementioned microscope, and 100x magnified photographs were taken. Three 2 mm straight lines were drawn arbitrarily in the extrusion direction of the magnified photographs (three lines for each observation location), and the number of bubbles b tangent to these lines was measured. From the measured number of bubbles b, the average bubble diameter B in the extrusion direction for each observation location was calculated using the following equation (2). The average value of the three locations was taken as the average bubble diameter B (average value) in the extrusion direction of the styrene resin extruded foam.

[0057] The average bubble diameter B (mm) in the extrusion direction for each observation point = 2 × 3 / number of bubbles b ...(2).

[0058] The vertical cross-sections in the width direction of the obtained styrene resin extruded foam were observed from the extrusion direction using the aforementioned microscope at three locations: the center in the width direction and 150 mm from one end to the opposite end in the width direction (the same location at both ends in the width direction). 100x magnified photographs were taken. Three 2 mm straight lines were drawn arbitrarily in the width direction of the magnified photographs (three lines for each observation location), and the number of bubbles c tangent to these lines was measured. From the measured number of bubbles c, the average bubble diameter C in the width direction for each observation location was calculated using the following equation (3). The average value of the three locations was taken as the average bubble diameter C (average value) in the width direction of the styrene resin extruded foam.

[0059] The average bubble diameter C (mm) in the width direction for each observation point = 2 × 3 / number of bubbles c ...(3).

[0060] The cell 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 even more preferably 0.8 or more and 1.2 or less. If the cell deformation rate is less than 0.7, the compressive strength will be low, and the extruded foam may not be able to secure strength suitable for the intended application. In addition, because the cells tend to return to a spherical shape, the extruded foam tends to have poor dimensional (shape) retention. On the other hand, if the cell deformation rate exceeds 2.0, the number of cells in the thickness direction of the extruded foam decreases, so the effect of improving thermal insulation due to the cell shape becomes smaller.

[0061] Furthermore, the bubble deformation rate of the styrene resin extruded foam according to one embodiment of the present invention can be determined from the average bubble diameter described above by the following formula (4).

[0062] Bubble deformation rate (unitless) = A (average value) / {[B (average value) + C (average value)] / 2} ... (4).

[0063] The thickness of the styrene resin extruded foam according to one embodiment of the present invention is preferably 10 mm to 150 mm, more preferably 15 mm to 130 mm, even more preferably 20 mm to 130 mm, even more preferably 20 mm to 120 mm, and particularly preferably 30 mm to 120 mm, considering its function as, for example, a building insulation material or an insulation material for a cold storage or refrigerated vehicle, from the viewpoint of thermal insulation, bending strength and compressive strength.

[0064] In addition, in the case of styrene resin extruded foam, as described in the examples and comparative examples of the present invention, after extrusion foam molding to impart shape, the surface on both sides perpendicular to the thickness direction may be cut to a depth of about 5 mm on each side in the thickness direction to obtain the product thickness. However, unless otherwise specified, the thickness in the styrene resin extruded foam according to one embodiment of the present invention refers to the thickness after extrusion foam molding to impart shape and before cutting.

[0065] Thus, by one embodiment of the present invention, a styrene-based resin extruded foam having excellent heat insulation and flame retardancy, as well as a beautiful appearance and sufficient thickness suitable for use, can be easily obtained. From these viewpoints, the styrene-based resin extruded foam of the present invention is particularly useful for applications such as building insulation materials and insulation materials for refrigerated vehicle bodywork.

[0066] [2. Method for producing styrene-based resin extruded foam] The components already explained in [1. Styrene-based resin extruded foam] will be used as references, and their explanation will be omitted here.

[0067] One embodiment of the method for producing the styrene-based resin extruded foam of the present invention is the following method.

[0068] A method for producing an extruded styrene resin foam by extruding a foamable styrene resin composition obtained by melt-kneading a styrene resin and a foaming agent, wherein the method satisfies the following conditions (a) to (c): (a) The styrene-based resin comprises a styrene-(meth)acrylic acid copolymer, (b) The content of the styrene-(meth)acrylic acid copolymer in 100% by weight of the styrene resin is 20 to 80% by weight, (c) The foaming agent comprises hydro(chloro)fluoroolefin, alkyl chloride, and water.

[0069] By adding water in addition to hydro(chloro)fluoroolefin and alkyl chloride as blowing agents to styrene resins, the thickness-forming properties of the styrene resin can be improved, making it possible to stably produce styrene resin extruded foams that have both thermal insulation and thickness-forming properties.

[0070] In one embodiment of the manufacturing method according to the present invention, the amounts of hydro(chloro)fluoroolefin and alkyl chloride added can be appropriately adjusted to satisfy the above-mentioned content in the styrene resin extruded foam.

[0071] While not particularly limited, the amount of hydro(chloro)fluoroolefin added is preferably 1.0 to 14.0 parts by weight, more preferably 2.0 to 12.0 parts by weight, and especially preferably 3.0 to 10.0 parts by weight, per 100 parts by weight of styrene resin. If the amount of hydro(chloro)fluoroolefin added is less than 1.0 part by weight per 100 parts by weight of styrene resin, the effect of improving thermal insulation by hydro(chloro)fluoroolefin tends not to be very significant. On the other hand, if the amount of hydro(chloro)fluoroolefin added exceeds 14.0 parts by weight per 100 parts by weight of styrene resin, the hydro(chloro)fluoroolefin may separate from the molten resin during extrusion foaming, potentially causing spot holes (traces where localized clumps of hydro(chloro)fluoroolefin have broken through the surface of the extruded foam and been released into the outside air) on the surface of the extruded foam, or reducing the closed-cell ratio and impairing thermal insulation.

[0072] While not particularly limited, the amount of alkyl chloride added is preferably 1.0 to 8.0 parts by weight, more preferably 1.5 to 7.0 parts by weight, and especially preferably 2.0 to 6.0 parts by weight, per 100 parts by weight of styrene resin. If the amount of alkyl chloride added is less than 1.0 part by weight per 100 parts by weight of styrene resin, the effect of improving the heat insulation properties due to alkyl chloride tends not to be very significant. On the other hand, if the amount of alkyl chloride added exceeds 8.0 parts by weight per 100 parts by weight of styrene resin, the alkyl chloride greatly plasticizes the styrene resin, which may worsen the heat resistance of the resulting styrene resin extruded foam.

[0073] In one embodiment of the manufacturing method according to the present invention, the amount of water added is preferably 0.1 to 1.5 parts by weight, more preferably 0.2 to 1.5 parts by weight, and particularly preferably 0.3 to 1.5 parts by weight, per 100 parts by weight of styrene resin. If the amount of water added is less than 0.1 parts by weight per 100 parts by weight of styrene resin, the effect of improving thickness due to water cannot be expected to be very significant. On the other hand, if the amount of water added exceeds 1.5 parts by weight per 100 parts by weight of styrene resin, there is a risk that the aesthetic appearance of the foam will deteriorate, such as the occurrence of spot holes on the surface of the extruded foam.

[0074] As one embodiment of the manufacturing method according to the present invention, other blowing agents may be added as the blowing agent, and other blowing agents described above [1. Styrene resin extruded foam] can be used similarly. Chemical blowing agents such as azo compounds and tetrazoles may also be used.

[0075] In one embodiment of the manufacturing method according to the present invention, the total amount of foaming agent added is preferably 2 to 20 parts by weight, and more preferably 2 to 15 parts by weight, per 100 parts by weight of styrene resin. If the amount of foaming agent added is 2 parts by weight or more, the foaming ratio can be sufficiently increased, so that properties such as lightness and heat insulation of the resin foam can be easily exhibited. If the amount of foaming agent added is 20 parts by weight or less, the occurrence of defects such as voids in the foam can be prevented.

[0076] In one embodiment of the manufacturing method according to the present invention, it is preferable to add a water-absorbing substance in order to stably perform extrusion foam molding. Specific examples of water-absorbing substances used in one embodiment of the present invention include water-absorbing polymers such as polyacrylate polymers, starch-acrylic acid graft copolymers, polyvinyl alcohol polymers, vinyl alcohol-acrylate copolymers, ethylene-vinyl alcohol copolymers, acrylonitrile-methyl methacrylate-butadiene copolymers, polyethylene oxide copolymers and derivatives thereof, as well as fine powders with a particle size of 1000 nm or less having hydroxyl groups on the surface, such as anhydrous silica (silicon oxide) having silanol groups on the surface [for example, AEROSIL manufactured by Nippon Aerosil Co., Ltd. is commercially available]; water-absorbing or water-swellable layered silicates such as smectite and swellable fluoromica, and organically treated products thereof; porous materials such as zeolite, activated carbon, alumina, silica gel, porous glass, activated clay, diatomaceous earth, and bentonite. The amount of water-absorbing substance added is adjusted as appropriate by the amount of water added, but it is preferably 0.01 to 5 parts by weight, and more preferably 0.1 to 3 parts by weight, per 100 parts by weight of styrene resin.

[0077] First, a styrene-based resin and, if necessary, the various additives mentioned above are supplied to the heating and melting section of an extruder having a die slit section (in other words, the resin composition is supplied to the heating and melting section of the extruder). At this time, a foaming agent can be added to the resin composition under high-pressure conditions at any stage (for example, while the resin composition is being heated and melted, or after the resin composition has been heated and melted). This completes the melting process.

[0078] Subsequently, the foamy molten material obtained in the melting process is cooled to a temperature suitable for extrusion foaming, and then the fluid gel is extruded through the die slit into a low-pressure region (for example, atmospheric pressure) to form a styrene-based resin extruded foam. This completes the foaming process.

[0079] Methods for incorporating various additives into styrene-based resins during the melting process include, for example, adding various additives to the styrene-based resin and mixing by dry blending; adding various additives to the molten styrene-based resin from a supply unit installed in the middle of the extruder; preparing a masterbatch containing high concentrations of various additives in the styrene-based resin using an extruder, kneader, Banbury mixer, rolls, etc., and mixing the masterbatch with the styrene-based resin by dry blending; and supplying various additives to the extruder using a separate supply unit from the styrene-based resin.

[0080] The heating temperature in the above-mentioned heating and melting section is above the melting temperature of the styrene resin used. The heating temperature is preferably such that molecular degradation of the resin due to the effects of additives is suppressed as much as possible (for example, around 150°C to 260°C). The melt-mixing time in the heating and melting section cannot be uniquely defined as it varies depending on the amount of styrene resin extruded per unit time and / or the type of extruder used as the melt-mixing section, and can be appropriately set as the time required for the styrene resin, foaming agent and additives to be uniformly dispersed and mixed.

[0081] The melt-mixing section can use any mechanism commonly used in conventional extrusion foaming, such as a screw-type extruder.

[0082] The pressure used when adding or injecting the foaming agent is not particularly limited, and any pressure higher than the internal pressure of the extruder or similar equipment is acceptable.

[0083] In the foaming process, one method of extrusion foaming is to release the aforementioned fluid gel from a high-pressure region to a low-pressure region through a die slit section having a straight slit shape for use in extrusion molding. In this way, an extruded foam is obtained. The shape of the die slit section is not particularly limited, and various die slit sections in this art can be used.

[0084] Styrene resin extruded foam may be molded as a plate-shaped foam, i.e., an extruded foam sheet. For example, a plate-shaped foam with a large cross-sectional area can be molded using a molding die installed in close contact with or adjacent to a slit die, and a molding roll installed adjacent to the downstream side of the molding die, etc. By adjusting the flow surface shape of the molding die and the die temperature, the desired cross-sectional shape, surface properties, and foam quality of the foam can be obtained. [Examples]

[0085] The following describes some embodiments of the present invention, but the present invention is not limited to these embodiments.

[0086] [Raw materials] The raw materials used in the examples and comparative examples are as follows:

[0087] ○ Styrene resin • Polystyrene A [Manufactured by PS Japan Co., Ltd., 680; MFR 7.0g / 10 mins] • Polystyrene B [Manufactured by PS Japan Co., Ltd., G9401; MFR 2.1g / 10 mins] • Styrene-methacrylic acid copolymer [Manufactured by PS Japan Co., Ltd., G9001; MFR 1.5g / 10 min, methacrylic acid content = 8% by weight]

[0088] ○ Heat radiation suppressant • Graphite [(Manufactured by Marutoyo Casting Materials Co., Ltd., M-885; flake graphite, average particle size 5.5 μm, fixed carbon content 89%)]

[0089] ○ Flame retardant • Mixed bromine-based flame retardant containing tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis(2,3-dibromopropyl) ether [Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., GR-125P]

[0090] ○ Flame retardant additive Triphenylphosphine oxide [Sumitomo Corporation Chemicals]

[0091] ○ Stabilizer • Bisphenol-A-glycidyl ether [(Manufactured by ADEKA Corporation, EP-13)] • Dipentaerythritol-adipic acid reaction mixture [Manufactured by Ajinomoto Fine Techno Co., Ltd., Prenlyzer ST210] Triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate [Manufactured by Songwon Japan Co., Ltd., Sonnox 2450FF]

[0092] ○Other additives • Talc [Manufactured by Hayashi Chemical Co., Ltd., Talc Powder PK-Z] • Calcium stearate [Manufactured by Sakai Chemical Industry Co., Ltd., SC-P] • Bentonite [(Manufactured by Hojun Co., Ltd., Bengelbright 11K)] • Silica [Manufactured by Evonik Degussa Japan Co., Ltd., Carplex BS-304F] • Stearic acid monoglyceride [manufactured by Riken Vitamin Co., Ltd., Rikemar S-100P]

[0093] ○ Foaming agent • HFO-1234ze [Manufactured by Honeywell Japan Co., Ltd.] • HCFO-1233zd [Manufactured by Honeywell Japan Co., Ltd.] • Dimethyl ether [manufactured by Iwatani Corporation] • Ethyl chloride [manufactured by Nippon Tokushu Kagaku Kogyo Co., Ltd.] • Isobutane [manufactured by Mitsui Chemicals, Inc.] • Water [Tap water from Settsu City, Osaka Prefecture].

[0094] [Measurement method] In the examples and comparative examples, various parameters were measured and evaluated according to the measurement methods described below.

[0095] (1) Thickness of styrene resin extruded foam (before cutting) In the extruded foam board with a cross-sectional shape of 60 mm thickness x 1000 mm width obtained in the [Preparation of Extruded Foam] described later, the thickness was measured at three points using a caliper [(Mitutoyo Corporation, M-type standard caliper N30)]: the center in the width direction, and 150 mm from one end to the opposite end in the width direction (the same location at both ends in the width direction). The average value of the three points was taken as the thickness of the styrene resin extruded foam.

[0096] (2) Per 1 kg of foam: amount of HFO-1234ze remaining, amount of HCFO-1233zd remaining, amount of isobutane remaining, amount of ethyl chloride remaining The obtained styrene resin extruded foam was left to stand under the standard temperature conditions of Class 3 (23°C ± 5°C) and standard humidity conditions of Class 3 (50+20°C, -10%RH) as specified in JIS K 7100. The residual amounts of HFO-1234ze, HCFO-1233zd, isobutane, and ethyl chloride after 7 days from production were evaluated using the following equipment and procedures. a) Equipment used: Gas chromatograph GC-2014 [(manufactured by Shimadzu Corporation)] b) Column used: G-Column G-950 25UM [Manufactured by the Chemicals Evaluation and Research Institute]

[0097] c) Measurement conditions; ·Inlet temperature: 65℃ Column temperature: 80°C Detector temperature: 100℃ • Carrier gas: High-purity helium • Carry gas flow rate: 30 mL / min • Detector: TCD ·Current: 120mA

[0098] A test piece of about 1.2 g, which varies depending on the apparent density cut out from the foam, was placed in a sealable glass container of about 130 cc (hereinafter referred to as "sealed container"), and the air in the sealed container was evacuated with a vacuum pump. Then, the sealed container was heated at 170 °C for 10 minutes to remove the blowing agent in the foam into the sealed container. After the sealed container returned to room temperature, helium was introduced into the sealed container to return to atmospheric pressure, and then a mixed gas containing 40 μL of HFO-1234ze, HCFO-1233zd, isobutane, and ethyl chloride was taken out with a microsyringe and evaluated under the use equipment and measurement conditions of a) to c) above.

[0099] (3) Apparent density (kg / m 3 ) The weight of the obtained styrene-based resin extruded foam was measured, and the length (extrusion direction) dimension, width dimension, and thickness dimension were measured.

[0100] From the measured weight and each dimension, the apparent density of the styrene-based resin extruded foam was determined based on the following formula. Then, the unit of the apparent density was converted to kg / m 3 Conversion. Apparent density (g / cm 3 ) = foam weight (g) / foam volume (cm 3 )

[0101] (4) Closed-cell ratio From three locations of the obtained styrene-based resin extruded foam: the center in the width direction, a location 150 mm from one end in the width direction towards the opposite end, and a location 150 mm from the other end in the width direction towards the opposite end, test pieces with a thickness of 40 mm × length (extrusion direction) of 25 mm × width of 25 mm were cut out. Using the test pieces, measurement was carried out according to Procedure C of ASTM-D2856-70, and the closed-cell ratio of each test piece was determined by the following formula. The average value of the closed-cell ratios at the three locations was taken as the closed-cell ratio of the styrene-based resin extruded foam. Closed-cell ratio (%) = (V1 - W / ρ) × 100 / (V2 - W / ρ)

[0102] Here, V1 (cm 3V2 (cm³) is the true volume of the test specimen (excluding the volume of non-closed-cell portions) measured using an air-comparative hydrometer [Tokyo Science Co., Ltd., air-comparative hydrometer, model 1000]. 3 ) is the apparent volume calculated from the external dimensions of the test specimen measured using a caliper [Mitutoyo Corporation, M-type standard caliper N30]. W(g) is the total weight of the test specimen. Also, ρ(g / cm³) 3 ) is the density of the styrene resin that makes up the extruded foam, and is 1.05 (g / cm³). 3 )

[0103] (5) Average bubble diameter in the thickness direction and bubble deformation rate As described above, the average bubble diameter in the thickness direction of the obtained styrene-based resin extruded foam was measured using a microscope [(KEYENCE Corporation, DIGITAL MICROSCOPE VHX-900)]. Furthermore, the average bubble diameter in the extrusion direction and width direction was measured, and the bubble deformation rate was determined from these values.

[0104] (6) Thermal conductivity In accordance with JIS A 9521, test specimens cut from styrene resin extruded foam with dimensions of 50 mm thickness × 300 mm length (extrusion direction) × 300 mm width were used, and the thermal conductivity at an average temperature of 23°C was measured using a thermal conductivity measuring device [Eiko Seiki Co., Ltd., HC-074]. Specifically, after the manufacture of the styrene resin extruded foam, test specimens of the above dimensions were cut out, and these specimens were subjected to standard temperature conditions of Class 3 (23°C ± 5°C) and standard humidity conditions of Class 3 (50°C) as specified in JIS K 7100. +20、-10 After standing under conditions of %RH, the thermal conductivity of the styrene resin extruded foam was measured one week (7 days) after its manufacture.

[0105] (7) JIS flammability In accordance with JIS A 9521, the flammability was evaluated using a test specimen measuring 10 mm thick × 200 mm long (extrusion direction) × 25 mm wide, according to the following criteria. The manufactured styrene resin extruded foam was cut into test specimens of the above dimensions, and these specimens were subjected to standard temperature conditions of Class 3 (23°C ± 5°C) and standard humidity conditions of Class 3 (50°C) as specified in JIS K 7100. +20、-10 The samples were left standing under conditions of %RH. One week (7 days) after the manufacture of the styrene resin extruded foam, the flammability was evaluated using test specimens. ○: Meets the criteria of "flame extinguishing within 3 seconds, leaving no residue, and not burning beyond the flammability limit indicator line." ×: Does not meet the above criteria.

[0106] (8) Appearance of the foam Based on the evaluation results of shape and surface properties described in (8)-1 and (8)-2 below, the following evaluation criteria were used for the determination. Pass: Both the shape and surface quality evaluation results are marked with a circle (○). Failure: At least one of the evaluation results for shape and surface properties is △ or ×.

[0107] (8)-1.Shape The extruded foam from the molding roll stage to before cutting was visually inspected and evaluated according to the following evaluation criteria. ○: The extruded foam is flat and without any undulation in the extrusion direction, width direction, or thickness direction. ×: The extruded foam is not in a flat, plate-like shape because it is wavy in one or more directions: the extrusion direction, the width direction, or the thickness direction.

[0108] (8)-2.Superficiality The extruded foam was visually inspected before and after cutting and evaluated according to the following evaluation criteria. Note that "surface" refers to the surface perpendicular to the thickness direction, and "after cutting" refers to the state after both surfaces have been cut to a depth of 5 mm on each side in the thickness direction, based on the thickness (average of 3 points) of the styrene resin extruded foam. ◎: The surface is beautiful, free from surface abnormalities such as flow marks, cracks, and peeling. ○: There are fine cracks less than 2mm in length, but there are no other surface abnormalities such as flow marks or tearing, and no traces of these remain on the surface after cutting. △: Surface abnormalities such as flow marks, cracks longer than 2 mm, and tearing are present, but these marks do not remain on the surface after cutting. ×: Surface abnormalities such as flow marks, cracks, and tearing are present, and traces of these remain on the surface even after cutting.

[0109] For the examples and comparative examples, graphite was added using a masterbatch prepared according to the following method.

[0110] (Manufacturing example) [Making a graphite masterbatch] Add 48% by weight of polystyrene A, 50% by weight of graphite [M-885, manufactured by Marutoyo Casting Co., Ltd.], and 2.0% by weight of monoglyceride stearate [Rikemar S-100P, manufactured by Riken Vitamin Co., Ltd.] (relative to 100% by weight of the total amount of polystyrene A, graphite, and monoglyceride stearate) to a Banbury mixer and mix at 5 kgf / cm². 2 The resin was melted and kneaded for 20 minutes under a load without heating or cooling. During this time, the resin temperature was measured to be 190°C. The strand-shaped resin was fed into a ruder and extruded at a discharge rate of 250 kg / hr through a die with small holes attached to the tip. After cooling and solidifying in a 30°C water bath, it was cut to obtain a graphite masterbatch.

[0111] (Example 1) [Preparation of resin mixture] The materials shown in Table 1 (materials other than the foaming agent) were dry-blended according to the formulations shown in Table 1 to obtain a resin mixture.

[0112] [Production of extruded foam] The obtained resin composition was supplied at approximately 800 kg / hr to an extruder consisting of a 150 mm diameter single-screw extruder (first extruder), a 200 mm diameter single-screw extruder (second extruder), and a cooler connected in series.

[0113] The resin composition supplied to the first extruder was heated to 250°C to melt or plasticize and knead to obtain a resin composition, and the foaming agent shown in Table 1 was injected under pressure into the resin composition near the tip of the first extruder.

[0114] Subsequently, the resin composition was cooled to the resin temperature shown in Table 1 in a second extruder and cooler connected to the first extruder. The mixture was then extruded into the atmosphere at the foaming pressure shown in Table 1 through a rectangular cross-section die (slit die) with the thickness shown in Table 1, which was installed at the tip of the cooler. Finally, an extruded foam sheet with a cross-sectional shape of 85 mm thick x 1000 mm wide was obtained using a molding die installed in close contact with the die and a molding roll installed downstream of it. The evaluation results of the obtained foam are shown in Table 1.

[0115] (Examples 2-9) Extruded foam was obtained by the same procedure as in Example 1, except that the formulation and manufacturing conditions shown in Table 1 were changed. The physical properties of the obtained extruded foam are shown in Table 1.

[0116] (Comparative Examples 1-6) Extruded foam was obtained by the same procedure as in Example 1, except that the formulation and manufacturing conditions shown in Table 2 were changed. The physical properties of the obtained extruded foam are shown in Table 2.

[0117] [Table 1]

[0118] [Table 2] As can be seen from Examples 1-9 and Comparative Examples 1-6, by including a styrene-methacrylic acid copolymer in a specific range in a styrene-based resin and a specific blowing agent, it is possible to easily obtain a styrene-based resin extruded foam that has excellent heat insulation properties, a beautiful surface, and sufficient thickness suitable for use. [Industrial applicability]

[0119] A styrene-based resin extruded foam according to one aspect of the present invention can be used, for example, as a core material for thermal insulation materials, sound-absorbing materials, vacuum insulation materials, cushioning materials, and fillers.

Claims

1. A styrene resin extruded foam comprising a styrene resin and a blowing agent, The styrene-based resin comprises a styrene-(meth)acrylic acid copolymer, The content of the styrene-(meth)acrylic acid copolymer in 100% by weight of the styrene-based resin is 20 to 80% by weight. The foaming agent comprises hydro(chloro)fluoroolefin and alkyl chloride. Styrene-based resin extruded foam.

2. The styrene-based resin extruded foam according to claim 1, wherein the constituent units derived from (meth)acrylic acid are 5 to 20% by weight relative to 100% by weight of all constituent units of the styrene-(meth)acrylic acid copolymer.

3. The styrene-based resin extruded foam according to any one of claims 1 to 2, wherein the content of the hydro(chloro)fluoroolefin is 0.10 to 1.0 mol per 1 kg of the styrene-based resin extruded foam.

4. The styrene resin extruded foam according to any one of claims 1 to 3, wherein the content of the alkyl chloride is 0.10 to 1.0 mol per 1 kg of the styrene resin extruded foam.

5. The styrene resin extruded foam according to any one of claims 1 to 4, wherein the styrene resin extruded foam contains 1.0 part by weight or more and 5.0 parts by weight or less of graphite per 100 parts by weight of styrene resin.

6. The styrene resin extruded foam according to any one of claims 1 to 5, wherein the thermal conductivity of the styrene resin extruded foam is 0.0224 W / mK or less.

7. The apparent density of the styrene resin extruded foam is 20 to 60 kg / m³. ３ The styrene resin extruded foam according to any one of claims 1 to 6.

8. The styrene resin extruded foam according to any one of claims 1 to 7, wherein the thickness of the styrene resin extruded foam is 10 mm or more and 150 mm or less.

9. A method for producing an extruded styrene resin foam by extruding a foamable styrene resin composition obtained by melt-kneading a styrene resin and a foaming agent, wherein the method satisfies the following conditions (a) to (c): (a) The styrene-based resin comprises a styrene-(meth)acrylic acid copolymer, (b) The content of the styrene-(meth)acrylic acid copolymer in 100% by weight of the styrene resin is 20 to 80% by weight, (c) The foaming agent comprises hydro(chloro)fluoroolefin, alkyl chloride, and water.

10. The aforementioned foaming agent is, in proportion to 100 parts by weight of styrene resin, (c1) The amount of hydro(chloro)fluoroolefin added is 3 to 10 parts by weight, (c2) The amount of alkyl chloride added is 2 to 6 parts by weight, (c3) The amount of water added is 0.3 to 1.5 parts by weight. A method for producing a styrene-based resin extruded foam according to claim 9.

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