Thermal insulation material

Abstract

To provide a thermal insulation material exhibiting superior thermal insulation and heat resistance under high-temperature conditions.SOLUTION: There is provided a thermal insulation material composed of a foamed styrene-based resin molded body that satisfies the following conditions (A)-(D): (A) a thermal conductivity (λ1) at an average temperature of 23°C is 0.0300 W / mK or less, (B) a thermal conductivity (λ2) at an average temperature of 35°C is 0.0320 W / mK or less, (C) a thermal conductivity (λ3) at an average temperature of 60°C is 0.0340 W / mK or less, and (D) a dimensional change rate after 24-hour heating at 90°C is within ±1%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a heat insulating material made of a foamed molded styrene resin. [Background technology]

[0002] Because of their light weight and excellent thermal insulation properties, thermal insulation materials using polystyrene as a base resin are widely used as thermal insulation materials for residential and industrial use. One way to impart excellent thermal insulation properties to such thermal insulation materials is to incorporate a radiation heat transfer inhibitor such as graphite into the thermal insulation material.

[0003] On the other hand, from the viewpoint of heat resistance, insulating materials using polystyrene as a base resin have a large rate of dimensional change when heated, which may make them difficult to use in high-temperature areas, for example, as insulating materials for hot water containers such as hot water tanks, or as insulating materials for building roofs. One approach to address this problem is to use a copolymer of styrene and another monomer as the base resin, thereby reducing the rate of dimensional change of the foamed molded product and imparting heat resistance (Patent Document 1, Patent Document 2).

[0004] However, while foams using heat-resistant styrene-based resins containing a radiation heat transfer inhibitor as described in Patent Documents 1 and 2 have been shown to have a certain degree of improvement in thermal insulation performance compared to conventional foams, it is difficult to say that they have sufficiently contributed to the recent trend toward further energy conservation in homes and housing equipment. Specifically, further improvements in thermal insulation performance are desired. Furthermore, the temperature environment to which thermal insulation materials are actually exposed is not limited to the room temperature environment of 23°C, but can also be much higher, specifically, up to approximately 30°C, 35°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and even 95°C. Therefore, a thermal insulation material that has excellent thermal insulation performance even at high temperatures and exhibits minimal dimensional change is desired. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-148661 [Patent Document 2] Japanese Patent Application Publication No. 2023-144509 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present disclosure is to provide a heat insulating material that has excellent heat insulating properties and heat resistance not only in a room temperature environment but also in a high temperature environment. [Means for solving the problem]

[0007] The present invention provides [1] A heat insulating material comprising a styrene-based resin foam molded product that satisfies the following (A) to (D): (A) Thermal conductivity (λ1) at an average temperature of 23°C is 0.0300 W / mK or less, (B) Thermal conductivity (λ2) at an average temperature of 35°C is 0.0320 W / mK or less; (C) Thermal conductivity (λ3) at an average temperature of 60°C is 0.0340 W / mK or less; (D) The dimensional change rate after heating at 90°C for 24 hours is within ±1%. [2] The heat insulating material according to [1], wherein the value obtained by dividing λ2 by λ1 is 1.04 or less. [3] The heat insulating material according to [1] or [2], wherein the value obtained by dividing λ3 by λ1 is 1.10 or less. [4] The heat insulating material according to [1] or [2], wherein the styrene-based resin foam molded product has a Vicat softening point of 106°C or higher and 125°C or lower and contains a first styrene-based resin having 2 to 20% by weight of a structural unit derived from (meth)acrylic acid. [5] The heat insulating material according to [1] or [2], wherein the styrene-based resin foam molded body has a content ratio of the first styrene-based resin relative to the entire base resin of 70% by weight or more and 100% by weight or less. [6] The heat insulating material according to [1] or [2], wherein the styrene-based resin foam molded body contains a radiation heat transfer inhibitor. [7] The heat insulating material according to [1] or [2], wherein the laser scattering intensity per unit solution concentration of the radiation heat transfer inhibitor in the styrene-based resin foam molded article is 5.0 {% / (mg / ml)} / wt% or more. [8] The heat insulating material according to [1] or [2], wherein the styrene-based resin foam molded product contains a bromine-based flame retardant in which a bromine atom is added to an aliphatic carbon. [9] The density of the styrene resin foam molded body is 15 kg / m 3 ~40kg / m 3 The heat insulating material according to [1] or [2],

[10] . The heat insulating material described in [1] or [2] that passes the combustion test of JIS A9511 Method A;

[11] . Heat insulating material described in [1] or [2] that meets the UL-94 HF-1 standard;

[12] The water absorption of the styrene resin foam according to JIS A 9511 is 1.0 g / 100 cm 2 The heat insulating material according to [1] or [2], which is the following:

[13] The heat insulating material according to [1] or [2], wherein the foamed molded body has an average cell diameter of more than 80 μm and less than 400 μm.

[14] The heat insulating material according to [1], wherein the styrene-based resin foamed molded body is a foamed bead molded body. Regarding. [Effects of the Invention]

[0008] The heat insulating material of the present invention exhibits excellent heat insulating performance in high temperature environments. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Base resin> The styrene-based resin used in this embodiment is not limited to a styrene homopolymer and / or a copolymer of styrene and another monomer or a derivative thereof, but may also be a blend of (a) a styrene homopolymer and / or a copolymer of styrene and another monomer or a derivative thereof with (b) a homopolymer of the above-mentioned other monomer or derivative, or a copolymer thereof, within a range that does not impair the effects of this embodiment.

[0010] Examples of the "other monomers or derivatives thereof" include: (a) styrene derivatives such as methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and trichlorostyrene; (b) polyfunctional vinyl compounds such as divinylbenzene; (c) (meth)acrylic acid compounds such as acrylic acid and methacrylic acid; (d) methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, and Examples of such compounds include (meth)acrylic acid ester compounds such as butyl methacrylate; (e) vinyl cyanide compounds such as (meth)acrylonitrile; (f) diene compounds or derivatives thereof such as butadiene; (g) 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. These compounds may be used alone or in combination of two or more.

[0011] In this embodiment, the base resin constituting the styrene-based foam molded article may contain other resins in addition to the styrene-based resin. Examples of such resins include vinyl resins such as polymethyl methacrylate, polyacrylonitrile resin, and vinyl chloride resin; polyolefin resins such as polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-propylene-butene terpolymer, and cycloolefin (co)polymer; polyolefin resins having a branched or crosslinked structure introduced therein to control the rheology; polyamide resins such as nylon 6, nylon 66, nylon 11, nylon 12, and MXD nylon; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyarylate, and polycarbonate; aliphatic polyester resins such as polylactic acid; and engineering plastics such as polyphenylene ether resin (PPE), modified polyphenylene ether resin (modified PPE), polyoxymethylene resin, polyphenylene sulfide resin, polyphenylene sulfide resin, aromatic polyether resin, and polyether ether ketone resin.

[0012] In this embodiment, it is preferable that the resin contains a first styrene-based resin having a Vicat softening point of 106°C or higher and 125°C or lower and containing 2 to 20% by weight of structural units derived from (meth)acrylic acid. The first styrene-based resin is, in other words, a styrene-(meth)acrylic acid copolymer containing 3 to 20% by weight of structural units derived from (meth)acrylic acid. The content of structural units derived from (meth)acrylic acid in the first styrene-based resin is usually 2 to 20% by weight, preferably 2 to 15% by weight, and more preferably 3 to 12% by weight. The Vicat softening point is measured according to JIS K 7206.

[0013] The melt mass flow rate (MFR) of the first styrene resin is preferably 0.5 to 5 g / 10 min, more preferably 1 to 4 g / 10 min, from the viewpoint of ensuring the molding processability and strength of the heat insulating material. The MFR is measured according to JIS K 7210.

[0014] In this embodiment, the composition may further contain a second styrene-based resin different from the first styrene-based resin. The second styrene-based resin preferably has a Vicat softening point of 95° C. or higher and 105° C. or lower. The second styrene-based resin is preferably a styrene homopolymer and / or a copolymer of styrene and another monomer or a derivative thereof in an amount of 70% by weight to 100% by weight.

[0015] In this embodiment, the first styrene-based resin is preferably the main component of the entire base resin. The main component here means 50% by weight or more of the entire base resin. The content of the first styrene-based resin relative to the entire base resin is preferably 70% by weight or more and 100% by weight or less. It is more preferably 70% by weight or more and 90% by weight or less, even more preferably 70% by weight or more and 85% by weight or less, and even more preferably 70% by weight or more and 80% by weight or less. When the content of the first styrene-based resin is 70% by weight or more, a foamed molded article with excellent heat resistance can be obtained. When the content of the first styrene-based resin is 90% or less, a good foamed molded article can be easily obtained using a general EPS molding machine.

[0016] In this embodiment, when the second styrene-based resin is contained, it is preferably 5% by weight or more and 50% by weight or less, more preferably 5% by weight or more and 30% by weight or less, even more preferably 10% by weight or more and 30% by weight or less, and even more preferably 15% by weight or more and 30% by weight or less, based on the entire base resin.

[0017] <Radiation heat transfer inhibitor> The heat insulating material according to one embodiment of the present disclosure can exhibit high heat insulating properties not only at room temperature but also at high temperatures by including a radiation heat transfer inhibitor. Here, the term "radiation heat transfer inhibitor" refers to a substance that has the property of reflecting, scattering, or absorbing light in the infrared region (e.g., a wavelength region of about 0.8 μm to 100 μm).

[0018] The radiation heat transfer inhibitor is not particularly limited, but carbon-based radiation heat transfer inhibitors are preferred in terms of dispersibility in polystyrene-based resins and cost. Examples of carbon-based radiation heat transfer inhibitors include graphite, carbon black, activated carbon, graphene, and carbon nanotubes, with graphite being more preferred. That is, it is particularly preferred that the radiation heat transfer inhibitor contains graphite as a main component. Here, "contains as a main component" refers to a content ratio of more than 50 wt%. In a preferred embodiment, the content ratio of graphite relative to the entire radiation heat transfer inhibitor is more than 50 wt%, more preferably 80 wt% or more, even more preferably 90 wt% or more, and particularly preferably 100 wt% (total amount).

[0019] Examples of the graphite include flake graphite, amorphous graphite, spherical graphite, and artificial graphite. In the present disclosure, the term "flake" also includes scaly, thin, or plate-like graphite. These graphites can be used alone or in combination of two or more. Among these, a graphite mixture containing flake graphite as a main component is preferred, and flake graphite is more preferred, because of its high radiation heat transfer suppression effect.

[0020] Examples of radiation heat transfer inhibitors other than carbon-based radiation heat transfer inhibitors include aluminum-based compounds, zinc-based compounds, magnesium-based compounds, titanium-based compounds, heat ray reflectors, metal sulfates, antimony-based compounds, metal oxides, heat ray absorbers, metal particles, etc. Specific examples include titanium oxide, aluminum, copper, etc.

[0021] The above-mentioned radiation heat transfer inhibitors may be used alone or in combination of two or more.

[0022] The average particle size of the radiation heat transfer inhibitor in the present disclosure is not particularly limited, but is preferably 12 μm to 2 μm, more preferably 10 μm to 2 μm, and even more preferably 7 μm to 2 μm. By setting the average particle size to 12 μm or less, the moldability during foam molding of the resin particles is improved, and by setting the average particle size to 2 μm or more, the resin particles can be handled without impairing their handleability. The average particle size of the radiation heat transfer inhibitor referred to here refers to the particle size D50 (i.e., 50% volume cumulative particle size) at which the cumulative volume of the total particles is 50% as measured and analyzed by a laser diffraction scattering method based on the Mie theory in accordance with ISO 13320:2009 and JIS Z8825-1.

[0023] The content of the radiation heat transfer inhibitor is not particularly limited, but for example, the content ratio of the radiation heat transfer inhibitor to the heat insulating material can be 2.0% by weight or more and 10.0% by weight or less, 3.0% by weight or more and 8.0% by weight or less, etc. With this blending amount, desired heat insulating properties can be achieved.

[0024] <Laser scattering intensity> In a heat insulating material according to one embodiment of the present disclosure, the laser scattering intensity per unit solution concentration of the radiation heat transfer inhibitor in the heat insulating material is preferably 5.0 {% / (mg / ml)} / wt% or more. When the laser scattering intensity is equal to or greater than a predetermined value, the dispersion of the radiation heat transfer inhibitor in the heat insulating material is favorable. As a result, the thermal conductivity of the heat insulating material is reduced, and the heat insulating properties are improved. Specific methods for measuring the laser scattering intensity will be described in the examples below.

[0025] <Flame retardant> The flame retardant contained in the thermal insulating material according to one embodiment of the present disclosure is not particularly limited, and various flame retardants can be used. In one preferred embodiment, the flame retardant is a bromine-based flame retardant, in which the bromine atom is attached to an aliphatic carbon.

[0026] Examples of brominated flame retardants include brominated bisphenol compounds, brominated styrene-butadiene copolymers, and brominated isocyanurate compounds. Specific examples of brominated bisphenol compounds include 2,2-bis[4-(2,3-dibromo-2-methylpropoxy)-3,5-dibromophenyl]propane (also known as tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)), 2,2-bis[4-(2,3-dibromopropoxy)-3,5-dibromophenyl]propane (also known as tetrabromobisphenol A-bis(2,3-dibromopropyl ether)), and the like. Brominated styrene-butadiene copolymers include brominated styrene-butadiene block copolymers, brominated random styrene-butadiene copolymers, and brominated styrene-butadiene graft copolymers. Examples of brominated isocyanurate compounds include tris(2,3-dibromopropyl)isocyanurate, etc. Other examples include tetrabromocyclooctane, etc. These brominated flame retardants may be used alone or in combination of two or more.

[0027] The content of the brominated flame retardant is not particularly limited, but for example, the content of the brominated flame retardant relative to the entire thermal insulation material can be 0.8% by weight or more and 5.0% by weight or less. If the content of the brominated flame retardant is 0.8% by weight or more, the desired flame retardant performance can be achieved. If the content of the brominated flame retardant is 5.0% by weight or less, the adverse effect on the dimensional change rate of the thermal insulation material at 90°C can be suppressed.

[0028] In one embodiment of the present disclosure, the insulating material may contain a blowing agent. The blowing agent is not particularly limited, but from the viewpoint of ease of achieving a high blowing ratio in actual use, volatile blowing agents are preferred, saturated hydrocarbons are more preferred, and aliphatic hydrocarbons having 4 or 5 carbon atoms are even more preferred. Examples of such hydrocarbons include normal butane, isobutane, normal pentane, isopentane, neopentane, cyclopentane, etc. These blowing agents may be used alone or in combination of two or more. In one preferred embodiment, the blowing agent contains an aliphatic hydrocarbon having 4 carbon atoms and / or an aliphatic hydrocarbon having 5 carbon atoms. In another preferred embodiment, the blowing agent contains at least an aliphatic hydrocarbon having 5 carbon atoms. Other blowing agents that may be used in this embodiment include hydrofluoroolefins, hydrochlorofluoroolefins, hydrofluorocarbons, nitrogen, carbon dioxide, etc.

[0029] The amount of foaming agent is not particularly limited, but for example, when the insulating material is 100% by weight, the amount of foaming agent is 10% by weight or less. Preferably, it is 5% by weight or less. If the content is 5% by weight or less, it is possible to suppress adverse effects on the dimensional change rate of the insulating material at 90°C.

[0030] <Other ingredients> The heat insulating material according to one embodiment of the present disclosure may further contain other components within a range that does not impair its performance, such as a stabilizer, a radical generator, a processing aid, a light resistance stabilizer, a nucleating agent, a foaming aid, an antistatic agent, a colorant such as a pigment, etc.

[0031] <Insulating material manufacturing method> The method for producing the thermal insulating material according to one embodiment of the present disclosure is not particularly limited, but a first production method includes a step of preparing a resin melt containing a base resin, a radiant heat transfer inhibitor, a flame retardant, a foaming agent, and, as necessary, various additives, and extruding the resin melt through a die having a plurality of small holes into pressurized circulating water, cutting the resulting expandable styrene-based resin particles with a rotary cutter, and pre-expanding and molding the resulting expandable styrene-based resin particles to produce a thermal insulating material.

[0032] In addition, a second manufacturing method is a method for manufacturing a heat insulating material in which a base resin, a radiation heat transfer inhibitor, a flame retardant, and, if necessary, various additives such as a radical generator and a heat stabilizer are melt-kneaded in an extruder, extruded through a die having many small holes, and then cut with a cutter to obtain resin particles (cold cut method or hot cut method), and the resin particles are suspended in water and impregnated with a blowing agent to obtain expandable styrene-based resin particles, which are then pre-expanded and molded.

[0033] The first production method will be described below.

[0034] <Method for producing expandable styrene resin particles> First, the base resin, radiant heat transfer inhibitor, brominated flame retardant, and other components, if necessary, are melt-kneaded in an extruder. Next, a blowing agent is dissolved and dispersed in the melt-kneaded mixture using the extruder or a mixing device installed downstream of the extruder. Next, the melt-kneaded mixture containing the blowing agent is extruded through a die with many small holes installed downstream of the extruder or the mixing device into a cutter chamber filled with pressurized circulating water. Immediately after extrusion, the melt-kneaded mixture is cut with a rotating cutter and cooled and solidified using the pressurized circulating water. This results in the desired expandable styrene-based resin particles. The melt-kneading using the extruder can be performed using a single extruder, multiple extruders connected together, or a second kneading device such as an extruder, a static mixer, or a mixer without a screw, and can be selected as appropriate.

[0035] <Method of manufacturing styrene resin foam molded article> A known method can be used to produce a foamed molded article using the expandable styrene-based resin particles. For example, the expandable styrene-based resin particles are pre-expanded to produce pre-expanded resin particles. The pre-expanded resin particles are then molded using a molding machine to produce a foamed molded styrene-based resin article.

[0036] <Pre-expanded resin particles> Pre-expanded resin particles can be produced, for example, by expanding expandable styrene-based resin particles 10 to 110 times with heated steam. The pre-expanded resin particles are used for molding after being cured for a certain period of time, if necessary. The obtained pre-expanded resin particles are molded (e.g., molded in a mold) with steam using a known molding machine to produce a heat insulating material. Depending on the shape of the mold used, molded articles with complex shapes and block-shaped molded articles can be obtained.

[0037] <Insulation density> In one embodiment of the present disclosure, the density of the insulating material is 15 to 40 kg / m 3 is preferably 18 to 30 kg / m 3 By satisfying the above range, the heat insulating performance and strength characteristics are excellent, and the heat insulating material is durable enough for residential and industrial use.

[0038] <Cell diameter of the insulation material> In one embodiment of the present disclosure, the average cell diameter constituting the thermal insulating material is preferably greater than 80 μm and less than 400 μm. It is more preferably 100 μm to 300 μm. If the average cell diameter exceeds 400 μm, the number of cell membranes in the thermal insulating material decreases, and sufficient thermal insulating performance may not be obtained. Furthermore, if the average cell diameter is less than 100 μm, the cell membrane thickness becomes extremely thin, which may lead to a decrease in the closed cell ratio of the thermal insulating material, deterioration in thermal insulating performance, deterioration in strength, and deterioration in heat resistance.

[0039] <Thermal conductivity of insulation material> In one embodiment of the present disclosure, the thermal conductivity (λ1) at an average temperature of 23°C is 0.0300 W / mK or less, preferably 0.0298 W / mK or less, and more preferably 0.0297 W / mK or less. Furthermore, the thermal conductivity (λ2) at an average temperature of 35°C is 0.0320 W / mK or less, and more preferably 0.0310 W / mK or less. Furthermore, the thermal conductivity at an average temperature of 60°C (λ3) is 0.0340 W / mK or less, preferably 0.0330 W / mK or less, and more preferably 0.0326 W / mK or less. The thermal conductivity is measured by a heat flow meter method in accordance with JIS A1412-2:1999, and the thermal conductivity at a temperature difference of 20°C is used. The above thermal conductivities enable the provision of a thermal insulating material with excellent thermal insulation performance even in high-temperature environments.

[0040] <Thermal conductivity ratio of insulating materials> In one aspect of the present disclosure, it is preferable that the value obtained by dividing the thermal conductivity (λ2) at an average temperature of 35°C by the thermal conductivity (λ1) at an average temperature of 23°C is 1.04 or less. It is also preferable that the value obtained by dividing the thermal conductivity (λ3) at an average temperature of 60°C by the thermal conductivity (λ1) at an average temperature of 23°C is 1.10 or less. These values ​​enable the material to provide excellent heat insulation and heat retention performance even when the ambient temperature rises to high levels.

[0041] <Dimensional change rate of insulation material> In one embodiment of the present disclosure, the dimensional change rate of the insulating material after heating for 24 hours in a 90°C atmosphere is within ±1%. This range allows for the provision of an insulating material with excellent dimensional stability even in high-temperature environments, and excellent durability. The measurement conditions will be described later.

[0042] <Flame retardant performance of insulation materials> In one embodiment of the present disclosure, by adding a flame retardant to a thermal insulation material, it is possible to provide a thermal insulation material that meets the JIS A 9511 A method. By satisfying this flame retardancy standard, it is possible to ensure the flame retardancy performance required for architectural thermal insulation materials, and to provide a thermal insulation material that is excellent not only in thermal insulation performance and heat resistance but also in flame retardancy performance. Furthermore, in one embodiment of the present disclosure, by adding a flame retardant to a thermal insulation material, it is possible to provide a thermal insulation material that satisfies HF-2 or less, more preferably HF-1, in the horizontal combustion test for foams specified in UL94. By having this flame retardancy, it can be used as a thermal insulation material for electrical appliances. The measurement conditions will be described later.

[0043] <Water absorption characteristics of insulation material> In one embodiment of the present disclosure, the water absorption property of the heat insulating material is a water absorption amount of 1.0 g / 100 cm according to JIS A 9511. 2 It is preferably 0.5 g / 100 cm or less, and more preferably 0.5 g / 100 cm 2 Below 0.1g / 100cm, most preferably 0.1g / 100cm 2 When the water absorption amount of the heat insulating material is within the above range, the heat insulating performance is less likely to be reduced due to water absorption, and high heat insulating performance is maintained for a long period of time.

[0044] The heat insulating material having the above-mentioned properties is suitable for use as a heat insulating material for houses, warehouses, roofs, hot water tanks, etc., but is not limited to these uses. [Example]

[0045] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0046] Example 1 [Preparation of expandable styrene resin particles] 93 parts by weight of methacrylic acid-modified heat-resistant polystyrene resin (G9001, manufactured by PS Japan Co., Ltd., 8% methacrylic acid, Vicat softening point: 124°C, MFR: 1.5g / 10 min), 4.5 parts by weight of graphite (SGP-40B flake graphite, average particle size: 5.8µm, manufactured by Marutoyo Foundry Co., Ltd.), and 2.5 parts by weight of brominated flame retardant (GR-170p, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., a mixture of 2,2-bis[4-(2,3-dibromo-2-methylpropoxy)-3,5-dibromophenyl]propane and a stabilizer) were fed into a 40mm diameter co-rotating intermeshing twin-screw extruder (first extruder). The cylinder temperature after the raw material feed section of the twin-screw extruder was set to 200°C, and the feed materials were melt-kneaded. Next, 8.0 parts by weight of mixed pentane (a mixture of 80% by weight of n-pentane and 20% by weight of isopentane (manufactured by SK Sangyo Co., Ltd.)) as a foaming agent was injected into the middle part of the cylinder after the raw material feed section of the twin-screw extruder relative to 100 parts by weight of the melt obtained by melt kneading, and further melt kneading was performed.

[0047] The resulting thermoplastic resin melt (the thermoplastic resin melt impregnated with the blowing agent) was then fed to a 90 mm diameter single-screw extruder (second extruder) through a continuation pipe set at 200°C. A gear pump set at 180°C and a diverter valve were connected to the tip of the single-screw extruder, and a die set at 250°C with 60 small holes, each 0.65 mm in diameter and 5.0 mm in land length, was connected downstream of the diverter valve. The cylinder temperature of the single-screw extruder was then set to 170°C to knead the thermoplastic resin melt. The melt obtained by melt kneading was then extruded through the die connected to the tip of the single-screw extruder at an extrusion rate (discharge) of 60 kg / hr into pressurized water at a temperature of 70°C and a water pressure of 0.9 MPa.

[0048] Immediately after that, the molten material was cut into particles using a rotary cutter with a blade. This produced expandable styrene resin particles for in-mold molding. The average particle weight of the resulting expandable styrene resin particles was 1 mg.

[0049] [Formation of pre-expanded particles] The obtained expandable styrene resin particles were placed in a pre-expanding machine and expanded by introducing steam at 0.1 MPa. This resulted in the formation of pre-expanded particles. The bulk expansion ratio of the obtained pre-expanded particles was 50 times (cc / g).

[0050] [Making insulation] The obtained pre-expanded particles were filled into a mold (mold for in-mold molding) attached to a molding machine for styrene foam, and steam of 0.08 MPa was introduced to cause in-mold foaming. After that, the resin foam molded body in the mold was cooled with water until the pressure pressing the mold was 0.015 MPa (gauge pressure). Then, it was measured in a size of 400 mm long x 400 mm wide x 25 mm thick, with a density of 20 kg / m 3 A heat insulating material (hereinafter sometimes referred to as "styrene-based resin heat insulating material") made of the above styrene-based resin foam molded article was produced.

[0051] Example 2 A styrene-based resin heat insulating material was prepared in the same manner as in Example 1, except that the methacrylic acid-modified heat-resistant polystyrene-based resin was changed to MR100 [manufactured by PS Japan Co., Ltd., 4% by weight of methacrylic acid, Vicat softening point: 109°C, MFR: 2.3 g / 10 min].

[0052] Example 3 A styrene-based resin heat insulating material was produced in the same manner as in Example 1, except that the base resin was changed to 65 parts by weight of a methacrylic acid-modified heat-resistant polystyrene resin (manufactured by PS Japan Co., Ltd.; G9001, 8% by weight of methacrylic acid, Vicat softening point: 124°C, MFR: 1.5 g / 10 min) and 28 parts by weight of a polystyrene resin (manufactured by PS Japan Co., Ltd.; 680, Vicat softening point: 97°C, MFR: 8 g / 10 min).

[0053] Example 4 Expandable styrene resin particles were prepared in the same manner as in Example 1, except that the base resin was changed to 75 parts by weight of a methacrylic acid-modified heat-resistant polystyrene resin (manufactured by PS Japan Co., Ltd.; MR100) and 18 parts by weight of a polystyrene resin (manufactured by PS Japan Co., Ltd.; 680). Then, pre-expanding and molding were carried out to obtain pre-expanded particles with a bulk ratio of 30 times and a density of 33 kg / m. 3 A styrene-based resin heat insulating material was obtained.

[0054] Example 5 Expandable styrene resin particles were prepared in the same manner as in Example 1, except that the base resin was changed to 75 parts by weight of a methacrylic acid-modified heat-resistant polystyrene resin (manufactured by PS Japan Co., Ltd.; MR100) and 18 parts by weight of a polystyrene resin (manufactured by PS Japan Co., Ltd.; 680). Then, pre-expanding and molding were carried out to obtain pre-expanded particles with a bulk ratio of 55 times and a density of 18 kg / m. 3 A styrene-based resin heat insulating material was obtained.

[0055] Example 6 A styrene-based resin insulation material was prepared in the same manner as in Example 1, except that the base resin was changed to 88 parts by weight of methacrylic acid-modified heat-resistant polystyrene-based resin (G9001 manufactured by PS Japan Co., Ltd.) and 9.5 parts by weight of graphite.

[0056] (Comparative Example 1) A styrene-based resin heat insulating material was produced in the same manner as in Example 2, except that graphite, a radiation heat transfer inhibitor, was not used and was replaced with talc (Talc Powder PK-C, manufactured by Hayashi Kasei Co., Ltd.).

[0057] (Comparative Example 2) A styrene-based resin insulation material was produced using the same process as in Example 1, except that the methacrylic acid-modified heat-resistant polystyrene-based resin (manufactured by PS Japan Co., Ltd.; G9001) was changed to a polystyrene-based resin (manufactured by PS Japan Co., Ltd.; 680).

[0058] Various properties of the heat insulating materials produced in each experimental example were measured by the following methods.

[0059] <Measurement of average particle size D50 of graphite and laser scattering intensity (%)> (1) Preparation of sample solution 500 mg of the insulating material was dissolved and dispersed in 20 mL of a 0.1% (w / w) Span 80 toluene solution to prepare a sample solution. The above-mentioned dissolution and dispersion refers to a state in which the resin is dissolved and the graphite is dispersed. The 0.1% (w / w) Span 80 toluene solution refers to toluene to which 0.1% (w / w) of the surfactant Span 80 has been added. Next, the sample solution was irradiated with ultrasonic waves in an ultrasonic cleaner to relax the aggregation of graphite. (2) Ultrasonic irradiation conditions Equipment used: AS ONE Corporation ultrasonic cleaner, model USM Oscillation frequency: 42kHz Irradiation time: 10 minutes Temperature: room temperature (3) Particle size measurement conditions Measurement equipment: Malvern Laser Diffraction Particle Size Distribution Analyzer Mastersizer 3000 Light source: 632.8nm red He-Ne laser and 470nm blue LED Dispersion unit: Wet dispersion unit Hydro MV The analysis was carried out under the following settings. The volume distribution was determined and the D50 particle size of the graphite in the sample was calculated by measurement and analysis using a laser diffraction / scattering method based on the Mie theory in accordance with ISO13320:2009 and JIS Z8825-1. Particle type: non-spherical Graphite refractive index: 2.42 Graphite absorption rate: 1.0 Dispersion medium: 0.1% (w / w) Span 80 toluene solution Refractive index of dispersion medium: 1.49 Agitation speed in dispersion unit: 2500 rpm Analysis model: General, single mode preserving Measurement temperature: room temperature (4) Measurement procedure 120 mL of 0.1% (w / w) Span 80 toluene solution was poured into the dispersion unit and stirred at 2500 rpm to stabilize. The light intensity measured by the central detector when irradiating the dispersion medium with a 632.8 nm red He-Ne laser beam without the sample solution sample in the measurement cell was taken as the transmitted light intensity Lb. Next, 2 mL of the ultrasonically treated sample solution was taken and added to the dispersion unit. One minute after adding the sample solution, the light intensity measured by the central detector when irradiating the dispersion medium with a 632.8 nm red He-Ne laser beam was taken as the transmitted light intensity Ls. The particle size (D50) was also measured at the same time. The laser scattering intensity Ob of the sample solution was calculated from the obtained Ls and Lb using the following formula: Ob = (1 - Ls / Lb) x 100 (%) The central detector is a detector located in front of the laser light output, and the light detected here is a measure of the transmitted light that was not used for scattering. The laser scattering intensity is a measure of the amount of laser light lost when the sample scatters the laser of the analytical device. (5) Calculation of laser scattering intensity per unit solution concentration of insulating material The laser scattering intensity X (% / (mg / ml)) per unit solution concentration of the heat insulating material was calculated using the following formula. X (% / (mg / ml)) = laser scattering intensity (Ob) / {sample weight (500 mg) / toluene amount (20 mL) × sample injection amount (2 mL) / total toluene amount in dispersion unit (120 mL + 2 mL)} Here, the laser scattering intensity per unit solution concentration is the value obtained by dividing the measured laser scattering intensity by the sample concentration in toluene. Because the measurement device used here is an instrument that requires measurement in solution, the sample concentration in the toluene solution was kept constant, and measurements were obtained for a constant sample amount. (6) Calculation of laser scattering intensity per unit solution concentration of radiation heat transfer inhibitor for thermal insulation The laser scattering intensity Y {% / (mg / ml)} / wt % per unit solution concentration of the radiation heat transfer inhibitor contained in the heat insulating material (hereinafter abbreviated as "measurement object") was calculated using the following formula. Y{% / (mg / ml)} / weight% = laser scattering intensity per unit solution concentration of the target (% / (mg / ml)) / graphite content of the target (weight%).

[0060] <Insulation density> A sample measuring 300 mm in length, 300 mm in width, and 25 mm in thickness was cut out from the styrene-based resin foam molded body. The weight (kg) of the sample was measured, and the length, width, and thickness were measured using a vernier caliper. The volume (m 3 ) was calculated, and the expansion ratio was calculated according to the following formula. Insulation density (kg / m 3 ) = sample weight (kg) / sample volume (m 3 ).

[0061] <Average cell diameter of insulation material> The styrene-based resin foam molded body was cut with a razor and the cross section was observed under an optical microscope. The number of cells present within a 1,000 μm x 1,000 μm square area of ​​the cross section was counted, and the value calculated using the following formula (area average diameter) was taken as the average cell diameter. The average cell diameter of five samples was measured, and the average was taken as the average cell diameter of the standard. Average cell diameter (μm) = 2 × [1000 μm × 1000 μm / (number of cells × π)] 1 / 2 .

[0062] <Measurement of thermal conductivity of insulation materials> A sample measuring 300 mm in length, 300 mm in width, and 25 mm in thickness was cut out from a styrene-based resin foam molded article. The sample was left standing at 23°C for one month, and then thermal conductivity (λ1) was measured at an average temperature of 23°C with a temperature difference of 20°C, thermal conductivity (λ2) was measured at an average temperature of 35°C with a temperature difference of 20°C, and thermal conductivity (λ3) was measured at an average temperature of 60°C with a temperature difference of 20°C using a thermal conductivity measuring device (HC-074, manufactured by Eiko Seiki Co., Ltd.) according to JIS A1412-2:1999 using the heat flow meter method.

[0063] <Measurement of dimensional change rate of insulation material> A sample with a length of 150 mm × width of 150 mm × thickness of 25 mm was cut out from the styrene resin foam molded body. After the sample was left standing at a temperature of 23°C for 168 hours, three straight lines were marked parallel to each other in the longitudinal and transverse directions at intervals of 50 mm at the center of the test piece. After placing the test piece in a hot air circulation dryer at 90°C for 24 hours, it was taken out and left standing at a place in the standard state (temperature 23 ± 2°C, humidity 50 ± 5%) for 1 hour. The dimensions of the vertical and horizontal lines were measured, and the heating dimensional change rate S (%) was calculated by the following formula. S = (L1 - L0) / L0 × 100 In the formula, S represents the heating dimensional change rate (%), L0 represents the dimension (mm) before heating, and L1 represents the dimension (mm) after heating.

[0064] <Evaluation of flame retardancy> <JIS A 9511 Method A Combustion Test> The styrene resin foam molded body was left standing at a temperature of 23°C for one month, and five test pieces with a length of 200 mm × width of 25 mm × thickness of 10 mm were cut out. Then, a pass / fail judgment was made in accordance with the combustion property measurement method A of JIS A 9511:2017. <ul 94 発泡体水平燃焼試験> The styrene resin foam molded product was left to stand at 23°C for one month, and five test pieces measuring 150mm long x 50mm wide x 13mm thick were cut out.The foam was then subjected to a horizontal combustion test in accordance with UL94 Seventh Edition to determine its compliance class. <Flame retardancy evaluation - oxygen index> The styrene resin foam molded article was left standing at 70°C for 168 hours and then at 23°C for 24 hours, after which the oxygen index was measured in accordance with JIS K7201.

[0065] <Measurement of water absorption of foam> A sample measuring 100 mm in length, 100 mm in width, and 25 mm in thickness was cut out from the styrene-based resin foam molded article. The water absorption of the sample was measured according to the water absorption measurement method of JIS A 9511 Test Method A.

[0066] [Table 1]

Claims

1. A heat insulating material comprising a foamed styrene resin molded product satisfying the following (A) to (D): (A) Thermal conductivity (λ1) at an average temperature of 23°C is 0.0300 W / mK or less; (B) a thermal conductivity (λ2) of 0.0320 W / mK or less at an average temperature of 35°C; (C) Thermal conductivity (λ3) at an average temperature of 60°C is 0.0340 W / mK or less; (D) The dimensional change rate after heating at 90°C for 24 hours is within ±1%.

2. The heat insulating material according to claim 1, wherein the value obtained by dividing λ2 by λ1 is 1.04 or less.

3. The heat insulating material according to claim 1 or 2, wherein a value obtained by dividing λ3 by λ1 is 1.10 or less.

4. The styrene-based resin foam molded product has a Vicat softening point of 106 ° C. or higher and 125 ° C. or lower, and contains a first styrene-based resin having 2 to 20 wt% of a structural unit derived from (meth)acrylic acid. The heat insulating material according to claim 1 or 2.

5. 3. The heat insulating material according to claim 1, wherein the styrene-based resin foam molded article has a content of the first styrene-based resin of 70% by weight or more and 100% by weight or less relative to the total weight of the base resin.

6. The heat insulating material according to claim 1 or 2, wherein the styrene-based resin foam molded article contains a radiation heat transfer inhibitor.

7. 3. The heat insulating material according to claim 1, wherein the styrene-based resin foam molded article has a laser scattering intensity per unit solution concentration of the radiation heat transfer inhibitor of 5.0% / (mg / ml) / wt % or more.

8. 3. The heat insulating material according to claim 1, wherein the styrene-based resin foam molded article contains a bromine-based flame retardant in which a bromine atom is added to an aliphatic carbon.

9. The density of the styrene resin foam molded article is 15 kg / m ３ ~40 kg / m ３ The heat insulating material according to claim 1 or 2,

10. 3. The heat insulating material according to claim 1, which passes the combustion test of JIS A9511 Method A.

11. 3. The heat insulating material according to claim 1 or 2, which satisfies the UL-94 HF-1 standard.

12. The water absorption of the styrene-based resin foam according to JIS A 9511 is 1.0 g / 100 cm ２ The heat insulating material according to claim 1 or 2, wherein:

13. The heat insulating material according to claim 1 or 2, wherein the foamed molded body has an average cell diameter of more than 80 μm and less than 400 μm.

14. 2. The heat insulating material according to claim 1, wherein the styrene resin foamed molded article is a foamed bead molded article.

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