Resin composition, foamed resin composition, and extruded foamed molded article

Abstract

The present invention provides a resin composition that can enhance the flame retardancy of various thermoplastic resins and impart excellent heat resistance, and a foamed resin composition suitable for obtaining extruded foamed molded articles that are highly flame-retardant and have excellent heat resistance. [Solution] The resin composition of the present invention contains a thermoplastic resin, a brominated flame retardant, and an organic phosphonic acid. The foamed resin composition of the present invention contains the resin composition and a foaming agent. The foamed resin composition of the present invention can produce an extruded foamed molded article with excellent flame retardancy.

Description

Technical Field

[0001] The present invention relates to a resin composition, a foamable resin composition, and an extrusion foam molded body.

Background Art

[0002] Foamed molded bodies typified by styrene resin foams are lightweight and are therefore widely used in a variety of fields, such as for heat insulation applications in home appliances and building materials, and for civil engineering applications such as earthwork methods. Since many thermoplastic resins such as styrene resins are formed only of carbon and hydrogen, once ignited, they generate black smoke and have the property of burning violently. Therefore, depending on the application of the foamed molded body, it is necessary to make the resin flame retardant by using a flame retardant.

[0003] Conventionally, for making a foamed molded body mainly composed of a thermoplastic resin flame retardant, hexabromocyclododecane (HBCD) has been used as a flame retardant, and it is known that a desired flame retardant effect can be obtained with a relatively small amount of use. In recent years, other brominated flame retardants have been adopted in place of HBCD. For example, brominated flame retardants such as tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) are often used (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, while conventional brominated flame retardants can impart flame retardancy to foams of certain resins, they still sometimes fail to provide sufficient flame retardancy and do not meet the increasingly stringent demands for flame retardancy in recent years, leaving room for improvement. In particular, foamed molded articles obtained using recycled thermoplastic resins (e.g., recycled polystyrene or recycled polypropylene) are more difficult to flame retard than those made from virgin resins (such as resins obtained from petroleum).

[0006] The present invention has been made in view of the above, and aims to provide a resin composition that can enhance the flame retardancy of various thermoplastic resins. [Means for solving the problem]

[0007] The inventors of this invention conducted extensive research to achieve the above objectives and, as a result, discovered that these objectives can be achieved by using a thermoplastic resin, a brominated flame retardant, and an organic phosphonic acid, thus completing the present invention.

[0008] In other words, the present invention encompasses, for example, the subject matter described in the following sections. Item 1 A resin composition containing a thermoplastic resin, a brominated flame retardant, and an organic phosphonic acid. Section 2 The resin composition according to item 1, wherein the organic phosphonic acid has a 5% weight loss temperature of 150°C or higher when heated under a nitrogen atmosphere at a heating rate of 10°C / min. Section 3 The resin composition according to claim 1 or 2, wherein the organic phosphonic acid is solid at 20°C. Section 4 The resin composition according to any one of claims 1 to 3, wherein the organic phosphonic acid is one or more selected from the group consisting of 1-hydroxyethane-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, and ethylenediaminetetramethylenephosphonic acid. Section 5 The resin composition according to any one of claims 1 to 4, wherein the brominated flame retardant is at least one selected from the group consisting of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tris(2,3-dibromopropyl) isocyanurate, tris(tribromophenoxy)triazine, and brominated epoxy oligomer. Section 6 The resin composition according to any one of claims 1 to 5, wherein the organic phosphonic acid is contained in an amount of 0.05 parts by mass or more and 1 part by mass or less per 100 parts by mass of the thermoplastic resin. Section 7 The resin composition according to any one of claims 1 to 6, wherein the organic phosphonic acid is contained in an amount of 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the brominated flame retardant. Section 8 A resin composition according to any one of claims 1 to 7, comprising at least one metal selected from the group consisting of transition metals, alkali metals, and alkaline earth metals. Section 9 The resin composition according to item 8, wherein the metal is included in the thermoplastic resin. Section 10 The thermoplastic resin is a resin composition according to any one of claims 1 to 9, comprising a polystyrene resin. Section 11 A foaming resin composition comprising a resin composition described in any one of items 1 to 10 and a foaming agent. Item 12 An extruded foamed molded article containing a foam of the foamed resin composition described in item 11. [Effects of the Invention]

[0009] The resin composition of the present invention can enhance the flame retardancy of various thermoplastic resins.

[0010] Furthermore, the foamed resin composition of the present invention can produce foamed molded articles with excellent flame retardancy, and such foamed molded articles exhibit excellent flame retardancy even if they are derived from recycled thermoplastic resin.

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail. In this specification, expressions such as "containing" and "including" include concepts such as "containing", "including", "substantially consisting of", and "consisting only of".

[0012] In the numerical ranges described step by step in this specification, the upper limit value or lower limit value of a numerical range at a certain step can be arbitrarily combined with the upper limit value or lower limit value of a numerical range at other steps. In the numerical ranges described in this specification, the upper limit value or lower limit value of the numerical range may be replaced with the value shown in the examples or a value uniquely derivable from the examples. Also, in this specification, numerical values connected by "~" mean a numerical range including the numerical values before and after "~" as the lower limit value and the upper limit value.

[0013] 1.Resin composition The resin composition of the present invention contains a thermoplastic resin, a brominated flame retardant, and an organic phosphonic acid. The resin composition of the present invention contains a thermoplastic resin, a brominated flame retardant, and an organic phosphonic acid as essential components, and thus has high flame retardancy. More specifically, by using the resin composition of the present invention, it is possible to produce a molded article having excellent flame retardancy.

[0014] In particular, even if the thermoplastic resin contained in the resin composition of the present invention is a recycled thermoplastic resin (hereinafter sometimes referred to as "recycled resin"), the molded article obtained from such a resin composition has high flame retardancy. Also, the molded article obtained from the resin composition may have excellent heat resistance in addition to flame retardancy.

[0015] Flame retardancy can be evaluated by LOI (Limiting Oxygen Index) or UL-94. For example, in the case of a polystyrene-based resin, flame retardancy can be evaluated by measuring the LOI (Limiting Oxygen Index), and in the case of a polyolefin resin, flame retardancy can be evaluated by UL-94.

[0016] (Thermoplastic resin) The thermoplastic resin is the main component contained in the resin composition of the present invention. The type of thermoplastic resin contained in the resin composition of the present invention is not particularly limited, and for example, known thermoplastic resins can be widely mentioned. The thermoplastic resin may be a so-called virgin resin, that is, a thermoplastic resin obtained from petroleum as a raw material, or a recycled thermoplastic resin (recycled resin).

[0017] Examples of the types of virgin resins include polystyrene resins, polyolefin resins, soft polyvinyl chloride resins, hard polyvinyl chloride resins, acrylic resins, acrylonitrile-butadiene-styrene resins, polycarbonate resins, etc. Among them, in terms of ease of extrusion foaming, the virgin resins are preferably polystyrene resins and polyolefin resins.

[0018] When the virgin resin is a polystyrene resin, its type is not particularly limited. For example, the polystyrene resins used for extrusion foaming can also be widely applied in the present invention. Examples include homopolymers of styrene monomers and copolymers of styrene and other monomers. The monomer units constituting the polystyrene resin can contain 50% by mass or more of styrene monomers, preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The styrene resin may be a homopolymer of polystyrene.

[0019] When the virgin resin is a polyolefin resin, its type is not particularly limited. For example, the polyolefin resins used for extrusion foaming can also be widely applied in the present invention. Examples of polyolefin resins include homopolymers or copolymers of olefin monomers such as ethylene and propylene, and copolymers containing olefin monomers as the main component and vinyl monomers copolymerizable with them. They may also be low-density polyethylene resins, high-density polyethylene resins, and polypropylene resins.

[0020] The method for producing virgin resin is not particularly limited; for example, it can be obtained by known methods, or it can be obtained from commercially available products.

[0021] On the other hand, examples of recycled resins include polystyrene resins, polyolefin resins, flexible polyvinyl chloride resins, rigid polyvinyl chloride resins, acrylic resins, acrylonitrile-butadiene-styrene resins, and polycarbonate resins. Among these, recycled polystyrene resins and recycled polyolefin resins are preferred as virgin resins because they are easy to extrude and foam, and it is easy to obtain extruded foam molded articles that are highly flame-retardant and have excellent heat resistance. Recycled polystyrene or recycled polypropylene can be preferably used.

[0022] The method for producing recycled resin is not particularly limited; for example, it can be obtained by known methods, or it can be obtained from commercially available products. Recycled resin can be obtained through so-called material recycling, in which used and recovered thermoplastic resin molded products are crushed and reused. In addition, recycled resin can be obtained through chemical recycling (chemical decomposition method) or mechanical recycling. Chemical recycling is a method of resynthesizing thermoplastic resin from raw materials obtained by chemically decomposing used thermoplastic resin molded products, etc.

[0023] Specifically, recycled resin can be obtained by removing foreign matter from used molded products, then crushing and washing them, and finally pelletizing them using an extruder.

[0024] The recycled resin may contain at least one metal selected from the group consisting of transition metals, alkali metals, and alkaline earth metals, as described below. Such metals do not necessarily have to exist as elemental elements in the recycled resin, but may be included as part of a compound.

[0025] In order to easily obtain an extruded foam molded article with excellent flame retardancy, it is preferable that the thermoplastic resin contains a polystyrene-based resin or a polypropylene resin. In particular, in the present invention, even if the thermoplastic resin is recycled polystyrene or recycled polypropylene, that is, even if the raw material resin of the extruded foam molded article is recycled polystyrene or recycled polypropylene, an extruded foam molded article with excellent flame retardancy can be obtained.

[0026] The thermoplastic resin may also contain other additives, as long as the effects of the present invention are not hindered. Examples of additives include light stabilizers, antioxidants, preservatives, surfactants, fillers such as inorganic particles, pigments, colorants, and fungicides. One or more of these additives may be included in the styrene-based resin.

[0027] (Bromine-based flame retardant) The brominated flame retardant is a component for imparting flame retardancy to the resin composition of the present invention, or a component for imparting flame retardancy to a molded article obtained from the resin composition.

[0028] As long as the brominated flame retardant is a compound that contains bromine and has the property of imparting flame retardancy, its type is not particularly limited, and known brominated flame retardants contained in extruded foam molded articles can be broadly applied in the present invention as well.

[0029] Examples of brominated flame retardants include brominated cycloalkane compounds, brominated aromatic compounds, bromine-containing isocyanurates, and bromine-containing epoxy compounds.

[0030] Examples of brominated aromatic compounds include tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tris(tribromophenoxy)triazine, hexabromobenzene, pentabromotoluene, hexabromobiphenyl, decabromobiphenyl, hexabromocyclodecane, decabromodiphenyl ether, octabromodiphenyl ether, hexabromodiphenyl ether, bis(pentabromophenoxy)ethane, ethylenebis(pentabromophenyl), ethylenebis(tetrabromophthalimide), tetrabromobisphenol A, and others, as well as compounds manufactured using brominated bisphenol A as a raw material. Examples include brominated polycarbonates such as polycarbonate oligomers and copolymers of the polycarbonate oligomer and bisphenol A; brominated epoxy compounds such as diexo compounds produced by the reaction of brominated bisphenol A with epichlorohydrin and monoepoxy compounds obtained by the reaction of brominated phenols with epichlorohydrin; halogenated brominated compound polymers such as poly(brominated benzyl acrylate), brominated polyphenylene ether, brominated bisphenol A, cyanuryl chloride and brominated phenol condensates, brominated polystyrenes such as brominated (polystyrene), poly(brominated styrene), and crosslinked brominated polystyrene; and crosslinked or non-crosslinked brominated poly(α-methylstyrene).

[0031] Examples of bromine-containing isocyanurates include tris(2,3-dibromopropyl)isocyanurate, and examples of bromine-containing epoxy compounds include bromine-containing epoxy oligomers. Examples of brominated cycloalkane compounds include hexabromocycloheptane, tetrabromocycloheptane, tetrabromocyclooctane, and hexabromocyclododecane.

[0032] In terms of easily obtaining an extruded foam molded article with high flame retardancy, it is preferable that the brominated flame retardant is at least one selected from the group consisting of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tris(2,3-dibromopropyl) isocyanurate, tris(tribromophenoxy)triazine, and brominated epoxy oligomers. In particular, in terms of easily obtaining an extruded foam molded article that can be obtained with high flame retardancy, it is preferable that the brominated flame retardant is at least one selected from the group consisting of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tris(2,3-dibromopropyl) isocyanurate, and brominated epoxy oligomers.

[0033] Brominated flame retardants can be manufactured by known methods or obtained from commercially available products. One or more brominated flame retardants are included in the resin composition.

[0034] (Organophosphonic acid) Organic phosphonic acids are organic compounds having a phosphonic acid moiety or a phosphonic acid-derived moiety. In the resin composition of the present invention, organic phosphonic acids are components that can act as chelating agents, and the inclusion of organic phosphonic acids in the resin composition can enhance flame retardancy and, in some cases, impart excellent heat resistance. Therefore, by including organic phosphonic acids in the resin composition, it is possible to achieve both flame retardancy and heat resistance in extruded foam molded articles, which are in a trade-off relationship. Furthermore, the inclusion of organic phosphonic acids in the resin composition of the present invention improves the appearance of the molded article, for example, making it more difficult to detect particulate foreign matter (foreign matter derived from organic phosphonic acids).

[0035] For example, a wide range of known organic phosphonic acid compounds can be used.

[0036] The organic phosphonic acid is preferably such that the 5% weight loss temperature when heated in a nitrogen atmosphere at a heating rate of 10°C / min is 150°C or higher. In this case, an extruded foam molded article with high flame retardancy is easily obtained, and in particular, an extruded foam molded article with particularly excellent heat resistance is easily obtained. The organic phosphonic acid is more preferably such that the 5% weight loss temperature when heated in a nitrogen atmosphere at a heating rate of 10°C / min is 180°C or higher, even more preferably 190°C or higher, even more preferably 200°C or higher, and particularly preferably 215°C or higher.

[0037] It is preferable that the organic phosphonic acid is solid at 20°C. In this case, the handling properties when preparing the resin composition are good, and the organic phosphonic acid is more easily dispersed uniformly in the molded article, making it easier to obtain an extruded foam molded article with excellent heat resistance.

[0038] The organic phosphonic acid is preferably one or more selected from the group consisting of 1-hydroxyethane-1,1-diphosphonic acid, aminotrimethylenephosphonic acid (also called aminotrismethylenephosphonic acid), 2-phosphonobutane-1,2,4-tricarboxylic acid (also called phosphonobutanetricarboxylic acid), and ethylenediaminetetramethylenephosphonic acid. In this case, flame retardancy can be further enhanced, and heat resistance can also be easily improved. From the viewpoint of particularly improving both flame retardancy and heat resistance, the organic phosphonic acid is especially preferably ethylenediaminetetramethylenephosphonic acid.

[0039] Organic phosphonic acids can be manufactured by known methods or obtained from commercially available products.

[0040] Organic phosphonic acids may be included in the resin composition as one or more types.

[0041] (Resin composition) The resin composition of the present invention contains the thermoplastic resin, the brominated flame retardant, and the organic phosphonic acid as essential components.

[0042] Preferably, the organic phosphonic acid is present in an amount of 0.05 parts by mass or more and 1 part by mass or less per 100 parts by mass of the thermoplastic resin. In this case, it becomes easier to obtain an extruded foam molded article with excellent flame retardancy, and the appearance of the molded article also improves, for example, making it less likely for particulate foreign matter to be found in the molded article.

[0043] The content of the organic phosphonic acid is more preferably 0.08 parts by mass or more, even more preferably 0.1 parts by mass or more, even more preferably 0.8 parts by mass or less, even more preferably 0.7 parts by mass or less, and particularly preferably 0.6 parts by mass or less, per 100 parts by mass of the thermoplastic resin.

[0044] Furthermore, it is preferable that the organic phosphonic acid is contained in an amount of 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the brominated flame retardant. In this case, it becomes easier to obtain an extruded foam molded article with excellent flame retardancy, and the appearance of the molded article also improves, for example, making it difficult to detect particulate foreign matter.

[0045] The content of the organic phosphonic acid may be 1.5 parts by mass or more per 100 parts by mass of the brominated flame retardant, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, particularly preferably 6 parts by mass or more, more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and particularly preferably 60 parts by mass or less.

[0046] The brominated flame retardant can be included in an amount of 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the thermoplastic resin, and preferably in an amount of 0.1 parts by mass or more and 10 parts by mass or less. In these cases, an extruded foam molded article with excellent flame retardancy is more easily obtained.

[0047] The content of the brominated flame retardant is more preferably 0.5 parts by mass or more, even more preferably 0.8 parts by mass or more, particularly preferably 1 part by mass or more, more preferably 8 parts by mass or less, even more preferably 7 parts by mass or less, and particularly preferably 5 parts by mass or less, per 100 parts by mass of the thermoplastic resin. In particular, from the viewpoint of easily achieving both flame retardancy and heat resistance, the brominated flame retardant is preferably contained in 4 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the thermoplastic resin. When the thermoplastic resin is a recycled polystyrene resin, these ranges can be preferably adopted as the content of the brominated flame retardant. However, if the brominated flame retardant is a combination of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) and tetrabromobisphenol A-bis(2,3-dibromopropyl ether), the brominated flame retardant may be present in 2 parts by mass or more, preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of the thermoplastic resin.

[0048] Of the brominated flame retardants, the content of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) is more preferably 0.5 parts by mass or more, even more preferably 0.8 parts by mass or more, particularly preferably 1 part by mass or more, and may be 10 parts by mass or less, preferably 9 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably 1.5 parts by mass or less, per 100 parts by mass of the thermoplastic resin. When the thermoplastic resin is a recycled polystyrene resin, these ranges can be preferably adopted as the content of the brominated flame retardant.

[0049] However, if the thermoplastic resin is a polyolefin resin such as recycled polyolefin resin, the brominated flame retardant may be included in an amount of, for example, 25 parts by mass or more per 100 parts by mass of the resin. However, in terms of improving heat resistance, an amount of 20 parts by mass or less is preferred, more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and also preferably 3 parts by mass or more, and more preferably 5 parts by mass or more.

[0050] The resin composition of the present invention may contain other components as long as it contains the thermoplastic resin, the brominated flame retardant, and the organic phosphonic acid as essential components. Furthermore, since the foamed resin composition described later can be prepared using the resin composition of the present invention, the resin composition of the present invention may contain components that can be included in a foamed resin composition.

[0051] The resin composition of the present invention may contain a flame retardant additive. In this case, it becomes easier to obtain an extruded foam molded article with particularly excellent flame retardancy.

[0052] As flame retardant additives, a wide range of known flame retardant additives that can be used in foamed molded articles can be listed. Examples of flame retardant additives include cumene peroxide, cumene hydroperoxide, di-t-butyl peroxide, di-t-hexyl peroxide, 2,3-diphenyl-2,3-dimethylbutane, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3, dicumyl peroxide, 2,3-dimethyl-2,3-diphenylbutane, etc. Other examples include phthalocyanine metal complexes such as phthalocyanine iron, phthalocyanine manganese, and phthalocyanine cobalt, and zeolites. Other examples of flame retardant additives include zinc fatty acid compounds such as zinc stearate, phosphate compounds such as resorcinol bis-dixylenyl phosphate, carboxylate compounds such as tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, and antimony oxide. When the thermoplastic resin is a polyolefin resin, particularly a recycled polypropylene resin, the flame retardant additive is preferably antimony oxide.

[0053] The content of the flame retardant additive is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.01 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and even more preferably 0.6 parts by mass or less, per 100 parts by mass of the thermoplastic resin. In particular, when the thermoplastic resin is recycled polypropylene resin, the content of the flame retardant additive is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, especially preferably 1 part by mass or more, and also preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less, per 100 parts by mass of the thermoplastic resin.

[0054] The resin composition of the present invention may also contain at least one metal selected from the group consisting of transition metals, alkali metals, and alkaline earth metals. Conventionally, when an extruded foam molded article contains the aforementioned metal, it has been difficult to improve its flame retardancy. In this regard, the resin composition of the present invention contains the thermoplastic resin, the brominated flame retardant, and the organic phosphonic acid as essential components, so it is possible to improve flame retardancy despite containing the aforementioned metal (especially transition metals). Furthermore, because the resin composition of the present invention contains the thermoplastic resin, the brominated flame retardant, and the organic phosphonic acid as essential components, it is sometimes possible to achieve both flame retardancy and heat resistance despite containing the aforementioned metal (especially transition metals).

[0055] When the resin composition of the present invention contains the aforementioned metal, it is particularly preferable that it is derived from a thermoplastic resin. For example, recycled resins such as recycled polystyrene may contain the aforementioned metal (especially transition metals). For this reason, it has been difficult to improve the flame retardancy of extruded foam molded articles using recycled resins such as recycled polystyrene in the past. However, as described above, the present invention makes it possible to improve the flame retardancy of extruded foam molded articles obtained from recycled resins containing the aforementioned metal. Furthermore, as described above, the present invention may also make it possible to achieve both flame retardancy and heat resistance in extruded foam molded articles obtained from recycled resins containing the aforementioned metal.

[0056] If the resin composition of the present invention contains the metal, its content is preferably, for example, 100 ppm by mass or more and 2000 ppm by mass or less relative to the thermoplastic resin, more preferably 150 ppm by mass or more, even more preferably 200 ppm by mass or more, and even more preferably 1800 ppm by mass or less, and even more preferably 1500 ppm by mass or less.

[0057] Examples of transition metals include Ti, Mn, Fe, Ni, Cu, Zn, and Zr. Examples of alkali metals include Li, Na, and K. Examples of alkaline earth metals include Mg, Ca, Sr, and Ba. The metals contained in the resin composition do not necessarily have to exist as elemental metals; they can also exist in the form of metal-containing compounds. These elemental metals or metal compounds may originate from thermoplastic resins.

[0058] The resin composition of the present invention can enhance the flame retardancy of various thermoplastic resins and may also impart excellent heat resistance. Furthermore, by using the resin composition of the present invention as a foaming resin composition as described later, it is possible to obtain an extruded foam molded article with excellent flame retardancy. Therefore, the resin composition of the present invention can be suitably used as a raw material for obtaining an extruded foam molded article. In particular, even an extruded foam molded article obtained using recycled resins such as recycled polystyrene as a raw material can exhibit high flame retardancy and may also have improved heat resistance.

[0059] The resin composition of the present invention may also contain known resin additives such as light stabilizers, ultraviolet absorbers, ultraviolet stabilizers, heavy metal deactivators, impact modifiers, colorants, lubricants, anti-dripping agents, crystal nucleating agents, antistatic agents, and compatibilizers, to the extent that they do not impair the effects of the present invention. When the foaming resin composition contains additives, their content can be, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less, relative to the mass of the styrene-based resin. The resin composition of the present invention may contain 50% by mass or more of a thermoplastic resin, a brominated flame retardant, and an organic phosphonic acid, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0060] The method for preparing the resin composition of the present invention is not particularly limited, and for example, it can be prepared by mixing the thermoplastic resin, the brominated flame retardant, the organic phosphonic acid, and one or more other components added as needed in a predetermined proportion.

[0061] 2. Foamed resin composition The present invention also encompasses foamed resin compositions. Such foamed resin compositions may contain the resin composition of the present invention described above and a foaming agent. That is, the resin composition of the present invention can be combined with a foaming agent to form a foamed resin composition.

[0062] The foaming agent may be incorporated into the foamable resin composition during the foaming process described later, or it may be incorporated into the foamable resin composition before foaming.

[0063] For example, a wide range of known blowing agents used in foam molding can be used. Specifically, examples include volatile organic blowing agents such as propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, 1-chloro-1,1-difluoroethane, monochlorodifluoromethane, monochloro-1,2,2,2-tetrafluoroethane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,3,3,3-pentafluoropropane, dichloromethane, 1,2-dichloroethane, dimethyl ether, diethyl ether, and ethyl methyl ether; inorganic blowing agents such as water, nitrogen, and carbon dioxide; and chemical blowing agents such as azo compounds. The blowing agent can be used alone or in combination of two or more types.

[0064] The amount of foaming agent can be appropriately set according to the desired foam performance and the molding method used. For example, the amount of foaming agent can be 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of thermoplastic resin.

[0065] The foaming resin composition may also contain various components that can be found in extruded foam molded articles, in addition to the foaming agent. Examples of such components include fatty acid metal salts such as zinc fatty acid; phosphate ester compounds such as phosphate esters and phosphite esters; heat stabilizers such as phosphite compounds, thioether compounds, hindered phenol compounds, hindered amine compounds, organotin compounds, phosphate esters and hydrotalcite; the aforementioned flame retardant additives; and foaming nucleating agents such as talc, bentonite, kaolin, mica, silica, clay and diatomaceous earth.

[0066] A foamed resin composition can be used to form a foamed molded article by various foaming methods. For example, an extruded foamed molded article can be obtained by extruding the foamed resin composition. Since such an extruded foamed molded article contains foam from the foamed resin composition, it has excellent flame retardancy. Furthermore, foamed molded articles obtained from foamed resin compositions may also have excellent flame retardancy and heat resistance. In particular, even if the thermoplastic resin contained in the foamed resin composition is a recycled resin such as recycled polystyrene or recycled polypropylene, it may be possible to obtain an extruded foamed molded article that has high flame retardancy and excellent flame retardancy and heat resistance.

[0067] The method for manufacturing the extruded foamed article is not particularly limited, and for example, known manufacturing methods can be widely employed. For example, the extruded foamed article can be manufactured by a manufacturing method comprising the following extrusion foaming process. Extrusion foaming process: A foamable resin composition (without foaming agent) is melted and mixed in an extruder, then a foaming agent (H) is injected into the extruder under pressure, and then the mixture is extruded into the atmosphere from the extruder die.

[0068] Through such an extrusion foaming process, a thermoplastic resin such as recycled polystyrene or recycled polypropylene is foamed and molded, and an extruded foamed molded article of the foamable resin composition is obtained. In the extrusion foaming process, the resin composition and other components as needed can be supplied to the extruder in any order, melted and mixed in the extruder, and then foamed and molded. Alternatively, some or all of the components can be mixed in advance to form a mixture, and then this mixture can be supplied to the extruder.

[0069] In identifying the inventions contained herein, the components (properties, structures, functions, etc.) described in each embodiment of this disclosure may be combined in any way. That is, this disclosure encompasses all subject matter consisting of any combination of the combinatable components described herein. [Examples]

[0070] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to the embodiments of these examples.

[0071] The raw materials used in the examples and comparative examples (thermoplastic resin, flame retardant, organic phosphonic acid, flame retardant additive, and other chelating agents) were as follows.

[0072] <Thermoplastic resin> • Recycle PS: Recycled polystyrene recovered and recycled from discarded home appliances (contains Na, Ca, Zn, Ba, and Fe as metal species, with a total metal content of 230 ppm by mass). Recycled PP: Recycled polypropylene recovered and recycled from discarded home appliances (contains Na, Ca, Zn, Ba, and Fe as metal species, with a total metal content of 300 ppm by mass).

[0073] <Flame retardant> • SR-130; Tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) (manufactured by Daiichi Kogyo Seiyaku Co., Ltd. as "Piroguard SR-130") • SR-720N: Tetrabromobisphenol A-bis(2,3-dibromopropyl ether) (manufactured by Daiichi Kogyo Seiyaku Co., Ltd. as "Piroguard SR-720N") • SR-245: Tris(tribromophenoxy)triazine (manufactured by Daiichi Kogyo Seiyaku Co., Ltd. as "Piroguard SR-245")

[0074] <Organophosphonic acid> • PH-540: Ethylenediaminetetramethylenephosphonic acid (manufactured by Kirest), 5% weight loss temperature is 237°C. ATMP: Aminotrismethylenephosphonic acid, 5% weight loss temperature is 194°C • PBTC: Phosphonobutanetricarboxylic acid, 5% weight loss temperature is 210°C

[0075] <Flame retardant additive> • Dicumyl:2,3-diphenyl-2,3-dimethylbutane • Zn-St: Zinc stearate (manufactured by Nitto Chemical Industries) ·LA-57: Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4- Tetracarboxylate (manufactured by ADEKA) • PX-200: Resorcinol bis-dixylenyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd.) • Phthalocyanine iron ATO: Antimony Oxide

[0076] <Other chelating agents> • EDTA: Ethylenediaminetetraacetic acid CDA-10: N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine (manufactured by ADEKA) • EDTA-4Na: Ethylenediaminetetraacetate tetrasodium • NTA: Nitrilotriacetic acid • NTA-4Na: Tetrasodium nitrilotriacetate Sodium gluconate: Sodium gluconate • Potassium pyrophosphate:

[0077] (Example 1) The components, excluding the foaming agent, were introduced into a 65 mm diameter extruder in the proportions shown in Table 1 below. The extruder was heated to 200°C to melt and plasticize the components, and the mixing was continued to prepare a foamed resin composition within the extruder. A two-stage extruder, with a 65 mm diameter and a 90 mm diameter extruder connected in series, was used. As shown in Table 1, the proportions of each component were 100 parts by mass of thermoplastic resin, 1.25 parts by mass of flame retardant, 0.20 parts by mass of organic phosphonic acid, and 0 parts by mass of flame retardant additive (i.e., not used).

[0078] Subsequently, a predetermined amount of carbon dioxide gas as a foaming agent was injected into the tip of a 65 mm extruder (opposite side to the die of the 90 mm diameter extruder) in a separate line, and the resin temperature (in-machine temperature) was cooled to 120 °C with a 90 mm diameter extruder. Thereafter, the resin composition was extruded into the atmosphere from a die lip with a rectangular cross-section of 2.5 mm in the thickness direction and 45 mm in the width direction provided at the tip of the 90 mm diameter extruder, thereby obtaining an extrusion foamed molded body of recycled polystyrene in the shape of a rectangular parallelepiped.

[0079] (Examples 2 to 9) An extrusion foamed molded body was obtained in the same manner as in Example 1, except that the raw materials and compounding amounts shown in Table 1 were changed.

[0080] (Examples 10 to 17) An extrusion foamed molded body was obtained in the same manner as in Example 1, except that the raw materials and compounding amounts shown in Table 2 were changed.

[0081] (Comparative Examples 1 to 7) An extrusion foamed molded body was obtained in the same manner as in Example 1, except that the raw materials and compounding amounts shown in Table 3 were changed.

[0082] (Examples 18 to 24 and Comparative Examples 8 to 11) An extrusion foamed molded body was obtained in the same manner as in Example 1, except that the raw materials and compounding amounts shown in Table 4 were changed.

[0083] (Evaluation Method) <LOI (Limiting Oxygen Index)> The oxygen index was measured according to JIS K-72, and the flame retardant performance was evaluated based on the following criteria. A: The oxygen index was 30.0 or more, and it had particularly excellent flame retardancy. B: The oxygen index was 28.0 or more and less than 30.0, and it had excellent flame retardancy. C: The oxygen index was less than 28.0, and it did not have excellent flame retardancy.

[0084] <ul-94> The test was performed using strip-shaped test specimens (length 127 mm x width 12.7 mm x thickness 1.6 mm) in accordance with UL-94. Flame retardancy was determined according to the UL-94 criteria. V-0 (Total burning time of 5 sticks: 50 seconds or less, maximum burning time: 10 seconds or less, no drip cotton ignition), V-1 (Total burning time of 5 sticks: 250 seconds or less, maximum burning time: 30 seconds or less, no drip cotton ignition), V-2 (Total burning time of 5 sticks: 250 seconds or less, maximum burning time: 30 seconds or less, with drip cotton ignition), NR (Not conforming to UL94 standards) The evaluation was based on four levels, with V-0 being considered a passing grade.

[0085] <Dispersibility> Dispersibility was evaluated based on the following criteria. The plate-shaped molded products were obtained by slicing the extruded foam molded body, which was undergoing the heat resistance test described later, with a cutter to form boards, compressing them with a twin-screw roll, then coarsely crushing them with a pulverizer, putting the resulting coarse material into a laboplast mill, melting and kneading it at 200°C, immediately removing it, and molding it into a 3.2 mm thick plate using a cooling press. A: No particulate foreign matter was found when the plate-shaped molded product was visually inspected. B: Particulate foreign matter was observed when the plate-shaped molded product was visually inspected.

[0086] <Heat resistance> The heat resistance of the foamed molded articles was evaluated from the degree of yellowing (YI: Yellow Index) of the foamed molded articles obtained in each example and comparative example. Specifically, the extruded foamed molded article under test was sliced ​​with a cutter to form a board, compressed with a twin-screw roll, and then coarsely crushed in a pulverizer. The coarsely crushed material was put into a laboplast mill, melted and kneaded at 200°C, immediately removed, and molded into a 3.2 mm thick plate using a cooling press. The resulting plate-shaped molded product was heated in a hot press at 220°C for 7 minutes, and then cooled with a cooling press. The cooled plate-shaped molded product was dissolved in methylene chloride at a concentration of 10% by mass, and the solution was filtered through a 0.45 μm filter. The resulting solution was used as the heat resistance test sample. The YI value of the sample was measured by transmission using a spectrophotometer (SE-6000, manufactured by Nippon Denshoku Industries Ltd.), and the heat resistance performance was evaluated based on the following criteria. A: The YI value was 20 or less, indicating particularly excellent heat resistance. The B:YI value exceeded 20, indicating poor heat resistance.

[0087] Tables 1-4 show the formulation conditions for obtaining the extruded foam molded articles for each example and comparative example, as well as the evaluation results of the obtained foam molded articles. A blank space in each table indicates that the raw material was not used.

[0088] As is clear from Tables 1-4, extruded foam molded articles obtained from resin compositions (foaming resin compositions) containing thermoplastic resin, brominated flame retardant, and organic phosphonic acid exhibited excellent flame retardancy and heat resistance. In particular, despite the thermoplastic resin being a recycled resin (recycled polystyrene or recycled polypropylene), it demonstrated excellent flame retardancy and heat resistance. It was found that, as in the comparative example, simply including a chelating agent other than organic phosphonic acid is insufficient to achieve both flame retardancy and heat resistance in extruded foam molded articles made from recycled resin.

[0089] [Table 1]

[0090] Table 2

[0091] Table 3

[0092] Table 4

Claims

1. A resin composition containing a thermoplastic resin, a brominated flame retardant, and an organic phosphonic acid.

2. The resin composition according to claim 1, wherein the organic phosphonic acid has a 5% weight loss temperature of 150°C or higher when heated under a nitrogen atmosphere at a heating rate of 10°C / min.

3. The resin composition according to claim 1, wherein the organic phosphonic acid is solid at 20°C.

4. The resin composition according to claim 1, wherein the organic phosphonic acid is one or more selected from the group consisting of 1-hydroxyethane-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, and ethylenediaminetetramethylenephosphonic acid.

5. The resin composition according to claim 1, wherein the brominated flame retardant is at least one selected from the group consisting of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tris(2,3-dibromopropyl) isocyanurate, tris(tribromophenoxy)triazine, and brominated epoxy oligomer.

6. The resin composition according to claim 1, wherein the organic phosphonic acid is contained in an amount of 0.05 parts by mass or more and 1 part by mass or less per 100 parts by mass of the thermoplastic resin.

7. The resin composition according to claim 1, wherein the organic phosphonic acid is contained in an amount of 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the brominated flame retardant.

8. The resin composition according to claim 1, comprising at least one metal selected from the group consisting of transition metals, alkali metals, and alkaline earth metals.

9. The resin composition according to claim 8, wherein the metal is included in the thermoplastic resin.

10. The resin composition according to claim 1, wherein the thermoplastic resin contains a polystyrene resin.

11. A foaming resin composition comprising the resin composition according to any one of claims 1 to 10 and a foaming agent.

12. An extruded foamed molded article containing a foam of the foamed resin composition described in claim 11.

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