Resin foam and method for producing resin foam

Abstract

The invention relates to a resin foam and a method for manufacturing the resin foam. The purpose of the present invention is to provide a resin foam having excellent flame retardancy and excellent moldability even in simultaneous processing of a plurality of pieces in which a plurality of products are molded using one mold. A resin foam obtained by foaming a base resin composition, the base resin composition containing (A) a resin including (A-1) a polyphenylene ether resin, (A-2) a polystyrene resin, and (A-3) a resin having a carbon-carbon unsaturated double bond, (B) a phosphorus-based flame retardant, and (C) a zinc compound, the resin (A) containing (A-1) a polyphenylene ether resin, (A-2) a polystyrene resin, and (A-3) a resin having a carbon-carbon unsaturated double bond. And 0.05 to 5.0 moles of zinc per 1 mole of the carbon-carbon unsaturated double bond of the resin (A-3) having the carbon-carbon unsaturated double bond.

Description

Technical Field

[0001] This invention relates to resin foams and methods for manufacturing resin foams. Background Technology

[0002] Flame-retardant plastics and metals have traditionally been used as materials for internal components in automobiles and electronic devices. These materials offer excellent flame retardancy and high strength, thus expanding their applications in automotive parts and electronic equipment. However, from an energy-saving perspective, there is a growing demand for materials that are lighter and possess superior flame retardancy, strength, and impact resistance. Flame-retardant foamed molded materials are one such material.

[0003] As examples of flame-retardant foamed molded articles, it is known that molded articles are formed by adding flame retardants to a blend of polystyrene-based resin and polyphenylene ether-based resin and then foaming it (e.g., Patent Documents 1 and 2).

[0004] However, in resin foams, more flame retardant is required to achieve the same level of flame retardancy as injection-molded articles. This is because, when comparing samples of the same size, the amount of resin per unit volume in the foam is less than that in the unfoamed resin, making it difficult to form a char layer and resulting in a longer burning time. Furthermore, the less resin in the foam compared to the unfoamed resin makes it more prone to softening due to the heat of combustion, leading to resin dripping during combustion, which is also a major cause of reduced flame retardancy. While increasing the amount of flame retardant added to the foam to improve flame retardancy does improve flame retardancy, it also reduces mechanical properties, heat resistance, and foaming properties. As a solution to these problems, Patent Document 3 discloses a technique of adding a rubber component to balance foaming and flame retardancy.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2000-95892

[0008] Patent Document 2: International Publication No. 2003 / 004552

[0009] Patent Document 3: Japanese Patent No. 4712914 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] On the other hand, besides the issue of reduced flame retardancy, there are also process problems in the manufacture of foamed molded parts, such as the foaming molding cycle taking longer than the injection molding cycle. Because of the time-consuming foaming molding cycle, there is an increasing demand for simultaneous processing (multiple parts produced in one mold per cycle) to optimize the molding process. However, simultaneous processing of multiple parts results in a reduction in the amount of resin foam filled in each product and a decrease in moldability.

[0012] Therefore, the object of the present invention is to provide a resin foam that has excellent formability and excellent flame retardancy even when multiple parts of multiple products are processed simultaneously using a single mold.

[0013] Furthermore, a further objective of the present invention is to provide a method for manufacturing resin foam that can produce resin foam with excellent formability and flame retardancy even when multiple products are molded simultaneously using a single mold.

[0014] Methods for solving problems

[0015] The present invention is described below.

[0016] [1] A resin foam, which is a resin foam formed by foaming a base resin composition, wherein,

[0017] The above-mentioned substrate resin composition comprises:

[0018] (A) Resin,

[0019] (B) Phosphorus-based flame retardants, and

[0020] (C) Zinc compounds,

[0021] The above-mentioned (A) resin comprises:

[0022] (A-1) Polyphenylene ether resin,

[0023] (A-2) Polystyrene resins, and

[0024] (A-3) Resins containing carbon-carbon unsaturated double bonds,

[0025] Each mole of carbon-carbon unsaturated double bonds in the resin having carbon-carbon unsaturated double bonds as described above (A-3) contains 0.05 to 5.0 moles of zinc.

[0026] [2] The resin foam described in [1] is in the shape of beads.

[0027] [3] The resin foam as described in [1] or [2], wherein the flame retardancy is V-2 to V-0 as determined by the UL94 vertical burning test based on the UL standard.

[0028] [4] The resin foam as described in any one of [1] to [3], wherein, relative to 100 parts by weight of the above-mentioned (A) resin, it comprises 5 to 25 parts by weight of the above-mentioned (B) phosphorus flame retardant.

[0029] [5] The resin foam as described in any one of [1] to [4], wherein the amount of the carbon-carbon unsaturated double bond is 0.001 to 0.2 moles relative to 1 mole of phosphorus contained in the above-mentioned base resin composition.

[0030] [6] The resin foam as described in any one of [1] to [5], wherein 100 parts by weight of the above-mentioned (A) resin contains 40 to 94 parts by weight of the above-mentioned (A-1) polyphenylene ether resin.

[0031] [7] The resin foam as described in any one of [1] to [6], wherein 100 parts by weight of the above-mentioned (A) resin includes 1 to 59 parts by weight of the above-mentioned (A-2) polystyrene resin.

[0032] [8] The resin foam as described in any one of [1] to [7], wherein the resin (A-3) having carbon-carbon unsaturated double bonds comprises structural units derived from styrene, and the proportion of structural units derived from styrene is 60 to 99% by mass relative to 100% by mass of the resin (A-3) having carbon-carbon unsaturated double bonds.

[0033] [9] The resin foam as described in any one of [1] to [8], wherein the above-mentioned (B) phosphorus flame retardant is at least one selected from the group consisting of phosphate esters and phosphazene compounds.

[0034]

[10] A method for manufacturing a resin foam, comprising the following steps:

[0035] In the granulation process, the resin foam described in any one of [1] to [9] is granulated after being mixed by an extruder to produce granules of the base resin composition;

[0036] The impregnation process allows the foaming agent to penetrate into the aforementioned granules; and

[0037] The foaming process involves foaming the granules impregnated with the aforementioned foaming agent to obtain a resin foam.

[0038]

[11] A method for manufacturing a resin foam, comprising the following steps:

[0039] The granulation process involves granulating the granules of the base resin composition obtained by extrusion mixing and / or the welded parts of the base resin composition granules generated during extrusion, as well as the resin blocks discharged from the extruder or die head, by mixing them in an extruder to produce granules of the base resin composition.

[0040] The impregnation process allows the foaming agent to penetrate into the aforementioned granules; and

[0041] The foaming process involves foaming the granules impregnated with the aforementioned foaming agent to obtain a resin foam.

[0042] in,

[0043] The above-mentioned substrate resin composition comprises:

[0044] (A) Resin,

[0045] (B) Phosphorus-based flame retardants, and

[0046] (C) Zinc compounds,

[0047] The above-mentioned (A) resin comprises:

[0048] (A-1) Polyphenylene ether resin,

[0049] (A-2) Polystyrene resins, and

[0050] (A-3) Resins containing carbon-carbon unsaturated double bonds,

[0051] Each mole of carbon-carbon unsaturated double bonds in the resin having carbon-carbon unsaturated double bonds as described above (A-3) contains 0.05 to 5.0 moles of zinc.

[0052] The effects of the invention

[0053] According to the present invention, a resin foam with excellent formability and excellent flame retardancy can be provided even when multiple parts of multiple products are processed simultaneously using a single mold.

[0054] In addition, according to the present invention, a method for manufacturing a resin foam can be provided, which can produce a resin foam with excellent formability and excellent flame retardancy even when multiple parts of multiple products are molded using a single mold during processing. Detailed Implementation

[0055] The following provides a detailed description of specific embodiments of the present invention (hereinafter also referred to as "this embodiment"). It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of its key points.

[0056] (Resin foam)

[0057] The resin foam of this embodiment is a resin foam formed by foaming a base resin composition, characterized in that...

[0058] The above-mentioned substrate resin composition comprises:

[0059] (A) Resin,

[0060] (B) Phosphorus-based flame retardants, and

[0061] (C) Zinc compounds,

[0062] (A) The resin contains:

[0063] (A-1) Polyphenylene ether resin,

[0064] (A-2) Polystyrene resins, and

[0065] (A-3) Resins containing carbon-carbon unsaturated double bonds,

[0066] One mole of carbon-carbon unsaturated double bonds in a resin having carbon-carbon unsaturated double bonds (A-3) contains 0.05 to 5.0 moles of zinc.

[0067] If it is the above-mentioned resin foam, then even when multiple parts of multiple products are molded using a single mold, the moldability is excellent and the flame retardancy is excellent.

[0068] The shape of the resin foam in this embodiment can be plate-shaped, cylindrical, prismatic, bead-shaped, etc., but is not limited to any one shape.

[0069] It should be noted that "bead shape" refers to a spherical or nearly spherical shape. In this specification, nearly spherical includes a perfect sphere, an ellipsoidal ball shaped like a rugby ball, or similar shapes.

[0070] The resin foam in this embodiment is not limited, but foamed particles are preferred. The foamed particles have a bead shape.

[0071] The flame retardancy of the resin foam in this embodiment, as determined by the UL94 vertical burning test according to the UL standard, is preferably V-2 to V-0. Furthermore, the flame retardancy of the resin foam, as determined by the UL94 vertical burning test according to the UL standard, is particularly preferably V-0.

[0072] The flame retardancy, determined based on the UL94 vertical burning test according to UL standards, is specifically evaluated using the methods described in the examples.

[0073] ((Base material resin composition))

[0074] The resin foam of this embodiment is a resin foam formed by foaming a base resin composition. The base resin composition includes (A) a resin, (B) a phosphorus-based flame retardant, and (C) a zinc compound.

[0075] The substrate resin composition of this embodiment is preferably a foaming substrate resin composition used to obtain a resin foam. By foaming the substrate resin composition of this embodiment, a resin foam for obtaining a foamed molded article can be manufactured. Alternatively, a foamed molded article can be manufactured directly.

[0076] [(A) Resin]

[0077] The resin (A) in the resin foam of this embodiment includes (A-1) a polyphenylene ether resin, (A-2) a polystyrene resin, and (A-3) a resin having carbon-carbon unsaturated double bonds.

[0078] <(A-1) Polyphenylene ether resin>

[0079] (A―1) Polyphenylene ether resins refer to polymers containing structural units (construction units) represented by the following general formula (I), such as homopolymers composed of structural units represented by the following general formula (I) and copolymers containing structural units represented by the following general formula (I).

[0080] [Chemistry 1]

[0081]

[0082] In general formula (I), R 1 R 2 R 3 and R 4 Each of these groups independently represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a phenyl group, or a haloalkyl or haloalkoxy group having at least two carbon atoms between the halogen atom and the benzene ring in general formula (I) and not containing an α-tertiary carbon atom. Additionally, in general formula (I), n is an integer representing the degree of polymerization.

[0083] Specific examples of polyphenylene ether resins include poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-1,4-phenylene) ether, poly(2-methyl-6-propyl-1,4-phenylene) ether, poly(2,6-dipropyl-1,4-phenylene) ether, poly(2-ethyl-6-propyl-1,4-phenylene) ether, poly(2,6-dibutyl-1,4-phenylene) ether, poly(2,6-dilauryl-1,4-phenylene) ether, poly(2,6-diphenyl-1,4-diphenylene) ether, and poly(2,6-diphenyl-1,4-diphenylene) ether. 6-Dimethoxy-1,4-phenylene) ether, poly(2,6-diethoxy-1,4-phenylene) ether, poly(2-methoxy-6-ethoxy-1,4-phenylene) ether, poly(2-ethyl-6-stearoyloxy-1,4-phenylene) ether, poly(2,6-dichloro-1,4-phenylene) ether, poly(2-methyl-6-phenyl-1,4-phenylene) ether, poly(2,6-dibenzyl-1,4-phenylene) ether, poly(2-ethoxy-1,4-phenylene) ether, poly(2-chloro-1,4-phenylene) ether, poly(2,6-dibromo-1,4-phenylene) ether, etc., but not limited to these. R in general formula (I) is particularly preferred. 1 and R 2 Alkyl groups having 1 to 4 carbon atoms, R 3 and R 4 Substances that are hydrogen or alkyl groups having 1 to 4 carbon atoms.

[0084] The manufacturing method of the aforementioned polyphenylene ether resin is not particularly limited and can be manufactured by known methods. For example, it can be easily manufactured by the method described in U.S. Patent No. 3,306,874, which uses a complex of cuprous salt and amine as a catalyst to oxidatively polymerize, for example, 2,6-xylenol. Furthermore, methods described in U.S. Patent Nos. 3,306,875, 3,257,357, and 3,257,358, Japanese Patent Publication Nos. 52-17,880, 50-51,197, and 63-152,628 can also be cited.

[0085] In addition, in this embodiment, as a polyphenylene ether resin, a modified polyphenylene ether resin in which part or all of the structural units constituting the polyphenylene ether resin are modified by unsaturated or saturated carboxylic acids or their derivatives can be used.

[0086] Examples of the modified polyphenylene ether resins described above include those disclosed in Japanese Patent Application Publication No. 2-276823 (US Patent No. 5159027, US Reissue Patent No. 35695), Japanese Patent Application Publication No. 63-108059 (US Patent No. 5214109, US Patent No. 5216089), and Japanese Patent Application Publication No. 59-59724.

[0087] Modified polyphenylene ether resin can be manufactured, for example, by reacting unsaturated or saturated carboxylic acids or their derivatives in the presence or absence of a free radical initiator. Alternatively, modified polyphenylene ether resin can be manufactured by dissolving polyphenylene ether resin with unsaturated or saturated carboxylic acids or their derivatives in an organic solvent in the presence or absence of a free radical initiator, and reacting the mixture in solution.

[0088] Examples of unsaturated carboxylic acids or their derivatives include maleic acid, fumaric acid, itaconic acid, halomaleic acid, cis-4-cyclohexene-1,2-dicarboxylic acid, bridged-cis-bicyclo(2,2,1)-5-heptene-2,3-dicarboxylic acid, etc.; anhydrides, esters, amides, imides, etc. of these dicarboxylic acids; as well as acrylic acid, methacrylic acid, etc.; esters, amides, etc. of these monocarboxylic acids.

[0089] Furthermore, examples of saturated carboxylic acids or their derivatives include compounds that undergo thermal decomposition at the reaction temperature during the manufacture of modified polyphenylene ether resins, thereby forming derivatives of the modified polyphenylene ether resin. Specifically, examples of saturated carboxylic acids or their derivatives include malic acid and citric acid.

[0090] The polyphenylene ether resin can be a resin consisting solely of polyphenylene ether resin, comprising 100% by mass of the aforementioned polyphenylene ether resin, or it can be a polymer alloy as described above. In the case of a polymer alloy, from the perspective of heat resistance and flame retardancy, the content of polyphenylene ether resin in 100% by mass of the polymer alloy is preferably 30-99% by mass, more preferably 40-95% by mass, and even more preferably 50-75% by mass.

[0091] The weight-average molecular weight (Mw) of the (A-1) polyphenylene ether resin is preferably 20,000 to 90,000, more preferably 40,000 to 80,000, and even more preferably 50,000 to 75,000. If the weight-average molecular weight of the (A-1) polyphenylene ether resin is 20,000 or more, the rupture of the resin bubble during foaming can be sufficiently suppressed. In addition, if the weight-average molecular weight of the (A-1) polyphenylene ether resin is 90,000 or less, the melt viscosity of the resin will not become too high, and there is a tendency to be able to granulate well in the granulation process (manufacturing of the base resin composition granules) in the manufacturing of foamed particles described later, without having to reach the processing limit of the die pressure.

[0092] It should be noted that the weight-average molecular weight (Mw) can be calculated as follows: for resin determination based on gel permeation chromatography (GPC), the peak molecular weight of the chromatogram is determined using a calibration curve derived from the determination of commercially available standard polystyrene (using the peak molecular weight of standard polystyrene).

[0093] The content of (A-1) polyphenylene ether resin relative to 100% by mass of the base resin composition is preferably 30-99% by mass, more preferably 40-95% by mass, and even more preferably 50-75% by mass.

[0094] In addition, in the resin foam of this embodiment, the (A-1) polyphenylene ether resin preferably contains 40 to 94 parts by weight, more preferably 50 to 90 parts by weight, and even more preferably 55 to 75 parts by weight in 100 parts by weight of (A) resin.

[0095] <(A-2) Polystyrene-based resins>

[0096] (A-2) Polystyrene-based resins refer to homopolymers of styrene and styrene derivatives, and copolymers in which styrene and styrene derivatives are the main components (containing more than 50% by mass in the polystyrene-based resin). It should be noted that, in this invention, even copolymers in which styrene and styrene derivatives are the main components, substances equivalent to the resins with carbon-carbon unsaturated double bonds described later in (A-3), i.e., substances with carbon-carbon unsaturated double bonds in the portion other than the aromatic ring (e.g., high-impact polystyrene (HIPS), styrene-butadiene copolymers, etc.), are not included in (A-2) polystyrene-based resins, but are included in (A-3) resins with carbon-carbon unsaturated double bonds.

[0097] Examples of styrene derivatives include o-methylstyrene, m-methylstyrene, p-methylstyrene, tert-butylstyrene, α-methylstyrene, β-methylstyrene, diphenylethylene, chlorostyrene, and bromostyrene.

[0098] Examples of (A-2) polystyrene resins that are homopolymers include polystyrene, polyα-methylstyrene, and polychlorostyrene.

[0099] Examples of (A-2) polystyrene resins belonging to the copolymer category include, for example, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, styrene-maleimide copolymers, styrene-N-phenylmaleimide copolymers, styrene-N-alkylmaleimide copolymers, styrene-N-alkylsubstituted phenylmaleimide copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methyl acrylate copolymers, styrene-methyl methacrylate copolymers, styrene-n-alkyl acrylate copolymers, styrene-n-alkyl methacrylate copolymers, ethyl vinylbenzene-divinylbenzene copolymers, and other binary copolymers; styrene-grafted polyethylene, styrene-grafted ethylene-vinyl acetate copolymers, (styrene-acrylic acid)-grafted polyethylene, styrene-grafted polyamide, and other graft copolymers; and so on.

[0100] They can be used individually or in combination of two or more.

[0101] The content of (A-2) polystyrene resin relative to 100% by mass of the base resin composition is preferably 1 to 70% by mass, more preferably 5 to 60% by mass, and even more preferably 10 to 50% by mass.

[0102] In addition, in the resin foam of this embodiment, the (A-2) polystyrene resin preferably contains 1 to 59 parts by weight, more preferably 3 to 40 parts by weight, and even more preferably 5 to 25 parts by weight in 100 parts by weight of (A) resin.

[0103] Polystyrene-based resins can be manufactured using any of the existing known manufacturing methods.

[0104] <(A-3) Resins with carbon-carbon unsaturated double bonds>

[0105] In the resin foam of this embodiment, (A-3) is not particularly limited to any resin having carbon-carbon unsaturated double bonds; examples include high-impact polystyrene (HIPS), styrene-butadiene copolymer, and ABS (acrylonitrile-butadiene-styrene resin). Regarding high-impact polystyrene (HIPS), fine rubber-like particles are blended or grafted into a styrene-based polymer matrix. Examples of such rubbers include polybutadiene, styrene-butadiene copolymer, polyisoprene, and ethylene-propylene copolymer.

[0106] In addition, in this invention, "resin having carbon-carbon unsaturated double bonds" refers to a resin having carbon unsaturated double bonds in the portion outside the aromatic ring.

[0107] In the resin foam of this embodiment, from the perspective of improving foamability, the amount of carbon-carbon unsaturated double bonds relative to 1 mole of phosphorus contained in the above-mentioned base resin composition is preferably 0.001 to 0.5 moles, more preferably 0.001 to 0.2 moles, and even more preferably 0.001 to 0.15 moles. Normally, if a flame retardant is added, the melt viscosity of the base resin decreases, making it prone to film breakage during foaming, thus making it difficult to obtain a high-quality resin foam. However, by keeping the amount of carbon-carbon unsaturated double bonds relative to 1 mole of phosphorus in the base resin composition within the above range, it is easy to adjust to the melt viscosity most suitable for foaming, and it is easy to obtain a resin foam with excellent independent bubble rate.

[0108] It should be noted that the amount of carbon-carbon unsaturated double bonds per mole of phosphorus in the base resin composition can be determined by ICP-MS, and by... 1 The amount of carbon-carbon unsaturated double bonds was determined by ¹H-NMR (ECS400, 400MHz) and calculated from (amount of carbon-carbon unsaturated double bonds) / (amount of phosphorus). Details of the determination method are described in the examples.

[0109] In the resin foam of this embodiment, from the perspective of foaming properties and heat resistance, the amount of carbon-carbon unsaturated double bonds in the substrate resin composition is preferably 0.1 to 10% by mass, more preferably 0.2 to 7.0% by mass, and even more preferably 0.2 to 5.0% by mass, relative to 100% by mass of the substrate resin composition.

[0110] It should be noted that the amount of carbon-carbon unsaturated double bonds in the substrate resin composition is determined by... 1 Values ​​measured by H-NMR (ECS400, 400MHz).

[0111] (A-3) The resin having carbon-carbon unsaturated double bonds preferably contains structural units derived from styrene. When the resin having carbon-carbon unsaturated double bonds in (A-3) contains structural units derived from styrene, the proportion of structural units derived from styrene relative to 100% by mass of the resin having carbon-carbon unsaturated double bonds in (A-3) is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 65% ​​by mass or more. Furthermore, the proportion of structural units derived from styrene relative to 100% by mass of the resin having carbon-carbon unsaturated double bonds in (A-3) is preferably 99% by mass or less, preferably 50% to 99% by mass, and more preferably 60% to 99% by mass.

[0112] It should be noted that the proportion of structural units from styrene is determined using... 1Values ​​measured by H-NMR.

[0113] Furthermore, in the resin foam of this embodiment, the resin having carbon-carbon unsaturated double bonds (A-3) preferably comprises 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, in 100 parts by mass of resin (A). Additionally, in the resin foam of this embodiment, the resin having carbon-carbon unsaturated double bonds (A-3) preferably comprises 59 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, in 100 parts by mass of resin (A).

[0114] (B) Phosphorus-based flame retardants

[0115] In this embodiment, (B) the phosphorus-based flame retardant can use a substance containing a phosphorus compound. Examples of phosphorus compounds include phosphate esters, phosphazene compounds having phosphorus and nitrogen atoms bonded in the main chain, trialkylphosphine oxide, and triphenylphosphine oxide.

[0116] As (B) phosphorus-based flame retardant, it is preferably at least one selected from the group consisting of phosphate esters and phosphazene compounds.

[0117] Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, tri(xylene) phosphate, toluene diphenyl phosphate, xylene phenyl phosphate, dimethyl ethyl phosphate, methyl dibutyl phosphate, ethyl dipropyl phosphate, hydroxyphenyl diphenyl phosphate, resorcinol bis(diphenyl phosphate), etc. Additionally, examples include phosphate ester compounds modified with various substituents, various condensed phosphate ester compounds, and phosphate ester compounds with cyclic structures.

[0118] Among these, phosphazene compounds, triphenyl phosphates, condensed phosphate compounds, and phosphate compounds with cyclic structures are preferred in terms of heat resistance, flame retardancy, and foaming properties.

[0119] They can be used individually or in combination of two or more.

[0120] In the base resin composition, relative to 100 parts by weight of resin (A), phosphorus-based flame retardant (B) preferably comprises 5 to 25 parts by weight. Furthermore, in the base resin composition, relative to 100 parts by weight of resin (A), phosphorus-based flame retardant (B) more preferably comprises 10 to 25 parts by weight, and even more preferably comprises 15 to 25 parts by weight.

[0121] [(C) Zinc compounds]

[0122] Examples of zinc compounds include zinc chloride, zinc oxide, zinc sulfide, zinc sulfate, zinc chromate, zinc stearate, zinc stannate, zinc gluconate, and zinc phosphide (Zn3P2).

[0123] They can be used individually or in combination of two or more.

[0124] The content of zinc compound relative to 100 parts by weight of resin (A) is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more. Furthermore, the content of zinc compound relative to 100 parts by weight of resin (A) is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and even more preferably 1 part by weight or less.

[0125] In the resin foam of this embodiment, 0.05 to 5.0 moles of zinc are contained in 1 mole of carbon-carbon unsaturated double bonds in the resin having carbon-carbon unsaturated double bonds (A-3). Furthermore, from the perspective of improving foamability, zinc is preferably contained in 0.1 to 4.0 moles, more preferably 0.2 to 3.5 moles, and even more preferably 0.3 to 3.0 moles in 1 mole of carbon-carbon unsaturated double bonds in the resin having carbon-carbon unsaturated double bonds (A-3). The reason for the preferred zinc content within the above range is speculated as follows: Typically, carbon-carbon unsaturated double bonds generate free radicals upon heating, forming a cross-linked structure. If the cross-linking reaction proceeds excessively, the molecular weight increases, and the product exists within the resin as a foreign gel. The elongation viscosity of the base resin becomes uneven, making it prone to film rupture during foaming, thus making it difficult to obtain a high-quality foam. Furthermore, even if a foam with a high rate of independent bubbles is obtained, if an excessive cross-linked structure is formed, insufficient expansion during molding will occur due to excessively high elongation viscosity, resulting in a poor appearance of the molded article. However, by setting the zinc content within the range of 1 mole relative to the carbon-carbon unsaturated double bonds in the base resin composition to the above range, zinc moderately inhibits the crosslinking reaction, making it easy to obtain a foam with excellent formability.

[0126] [Other Additives]

[0127] In this embodiment, the base resin composition may contain other additives in addition to (A) resin, (B) phosphorus flame retardant and (C) zinc compound.

[0128] Other additives may include flame retardants other than (B) phosphorus-based flame retardants, flame retardant auxiliaries, heat stabilizers, antioxidants other than those mentioned above, antistatic agents, inorganic fillers, anti-dripping agents, ultraviolet absorbers, light absorbers, plasticizers, release agents, dyes and pigments, rubber components, and resins other than those mentioned in (A-1) to (A-3) above. These can be added within the scope of not impairing the effects of the present invention.

[0129] The content of other additives is preferably 0 to 40 parts by weight, more preferably 0 to 20 parts by weight, and even more preferably 0 to 5 parts by weight, relative to 100 parts by weight of resin (A).

[0130] To achieve adequate flame retardancy, the base resin composition preferably contains additional flame retardants other than (B) phosphorus-based flame retardants.

[0131] Other flame retardants include organic and inorganic flame retardants. Organic flame retardants include halogenated compounds (represented by bromine compounds) and non-halogenated compounds (represented by phosphorus compounds and silicone compounds). Inorganic flame retardants include metal hydroxides (represented by aluminum hydroxide and magnesium hydroxide) and antimony compounds (represented by antimony trioxide and antimony pentoxide). From an environmental perspective, non-halogenated flame retardants are preferred, phosphorus and silicone flame retardants are more preferred, and phosphorus-based flame retardants are even more preferred.

[0132] [Method for manufacturing the substrate resin composition]

[0133] The method for manufacturing the base resin composition is not particularly limited. For example, one method involves mixing (A) resin, (B) phosphorus-based flame retardant, and (C) zinc compound, along with optional components, using a Henschel mixer, drum mixer, or V-type agitator, followed by mixing using a single-screw or multi-screw extruder, heated rollers, kneader, or Banbury mixer. From a productivity perspective, mixing using an extruder equipped with a degassing and pressure-reducing device is preferred. Alternatively, pre-mixing can be avoided, and each component can be continuously fed into the extruder individually or together using a metering feeder. The mixing temperature depends on the preferred processing temperature of the base resin, for example, 140–350°C, preferably 180–300°C.

[0134] In this embodiment, the base resin composition is preferably granules (i.e., base resin composition granules). Base resin composition granules can be used to manufacture resin foams. By foaming the base resin composition granules of this embodiment, a resin foam for obtaining a foamed molded body can be manufactured; alternatively, a foamed molded body can also be manufactured directly.

[0135] By using base resin composition granules, it is possible to obtain resin foams with good moldability and foaming properties, as well as foamed molded bodies with excellent flame retardancy and appearance.

[0136] The shape of the base resin composition granules in this embodiment is preferably approximately circular when cut perpendicular to the length direction. Examples include approximately columnar or approximately spherical shapes, with spherical shapes being preferred.

[0137] It should be noted that, in this specification, "approximately circular" includes a perfect circle, an ellipse, or similar shapes with rounded corners. "Approximately cylindrical" includes not only columns with a constant cross-section but also shapes whose cross-sectional shape changes (such as shapes where the cross-sectional diameter decreases at both ends along the length direction). "Approximately spherical" includes a perfect sphere, an ellipsoidal shaped like a rugby ball, or similar shapes.

[0138] -Method for manufacturing granules of the base resin composition-

[0139] There is no particular limitation on the manufacturing method of the base resin composition granules. Examples of methods include granulating the base resin composition by means of, for example, thermal cutting, underwater cutting, or wire cutting. Among these, thermal cutting and underwater cutting are preferred because pores are less likely to be generated near the surface of the granules. Underwater cutting is preferred because it is easy to efficiently produce near-spherical granules with the above characteristics.

[0140] When using underwater cutting, the circulating water pressure is preferably 1.0 to 2.0 bar. This is believed to have the following effects: by applying water pressure during cutting, voids can be suppressed in the water, preventing cutting damage and resulting in a uniform pellet shape; and by applying pressure to the molten resin exiting the die, the pellet shape is made closer to a spherical shape. It should be noted that in this specification, pressure is indicated by gauge pressure.

[0141] Furthermore, the higher the temperature of the circulating water used for underwater cutting, the better; preferably 90°C or higher, and more preferably 95°C or higher. By keeping the temperature of the circulating water within the above range, the cooling rate of the molten resin can be slowed down, the temperature difference between the resin surface and the interior can be reduced, the formation of pores can be easily suppressed, or even if pores are formed, their size can be easily reduced.

[0142] (Resin foam)

[0143] The resin foam of this embodiment is a resin foam formed by foaming a base resin composition comprising (A) resin, (B) phosphorus-based flame retardant, and (C) zinc compound. Examples of (A) resin, (B) phosphorus-based flame retardant, and (C) zinc compound are the same substances contained in the aforementioned base resin composition, and their amounts can also be the same.

[0144] The resin foam of this embodiment is formed by foaming the above-mentioned base resin composition. Alternatively, it can be formed by foaming the above-mentioned base resin composition granules.

[0145] In this embodiment, the expansion ratio of the resin foam is preferably 3 to 50 cc / g, more preferably 5 to 15 cc / g, and even more preferably 6 to 12 cc / g. If the expansion ratio of the resin foam is 50 cc / g or less, the independent bubble rate is high, and it tends to exhibit excellent moldability. If the expansion ratio of the resin foam is 3 cc / g or more, it tends to fully achieve the goal of lightweighting the component.

[0146] Regarding the expansion ratio of resin foam, after determining the weight W (g) of the resin foam, the volume V (cc) is determined using a water bath. The volume is divided by the weight, and the resulting value is taken as the expansion ratio of the resin foam.

[0147] In this embodiment, the independent bubble rate of the resin foam is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. If the independent bubble rate of the resin foam is 80% or more, it tends to exhibit excellent moldability.

[0148] Regarding the independent bubble rate of resin foam, the true volume (Vxp) of resin foam with a known expansion ratio (cc / g) can be measured using an air comparison hydrometer manufactured by Beckman Co., Ltd., and the independent bubble rate Sp (%) can be calculated using the following formula.

[0149] Sp(%)={(Vxp-Wp / ρp) / (Vap-Wp / ρp)}×100

[0150] Vxp: True volume of the resin foam (cm³) 3 )

[0151] Vap: Volume of resin foam (expansion ratio × mass) (cc)

[0152] Wp: Mass of the resin foam (g)

[0153] ρp: Density of the resin composition used as the base material for the resin foam (g / cm³) 3 )

[0154] -Manufacturing method of resin foam-

[0155] The method for manufacturing the resin foam in this embodiment is not particularly limited. For example, extrusion foaming, in which gas is injected into molten resin in an extruder to cause foaming, or a method including the following steps: a granulation step for producing granules of a base resin composition; an impregnation step for impregnating a foaming agent into the granules of the base resin composition; and a foaming step for foaming the granules of the base resin composition to obtain a resin foam; and so on. Furthermore, in the method for manufacturing the resin foam, the following granulation step may be performed: feeding the granules of the base resin composition obtained by extrusion mixing, the welded material of the base resin composition produced during extrusion, the resin block discharged from the extruder or die, or the resin foam back into the extruder to produce granules of the base resin composition. In addition, the granulation step may also be a granulation step for producing granules of the base resin composition by mixing the resin foam of this embodiment in an extruder and then granulating it.

[0156] The method for manufacturing the resin foam of this embodiment preferably includes the following steps:

[0157] In the granulation process, the resin foam of this embodiment is granulated after being mixed by an extruder to produce granules of the base resin composition.

[0158] The impregnation process allows the foaming agent to penetrate into the granules; and

[0159] The foaming process involves foaming granules impregnated with a foaming agent to obtain a resin foam.

[0160] In addition, another embodiment of the method for manufacturing a resin foam includes the following steps:

[0161] The granulation process involves granulating the granules of the base resin composition obtained by extrusion mixing and / or the welded parts of the base resin composition granules generated during extrusion, as well as the resin blocks discharged from the extruder or die head, by mixing them in an extruder to produce granules of the base resin composition.

[0162] The impregnation process allows the foaming agent to penetrate into the granules; and

[0163] The foaming process involves foaming granules impregnated with a foaming agent to obtain a resin foam.

[0164] The manufacturing method is characterized by,

[0165] The substrate resin composition comprises:

[0166] (A) Resin,

[0167] (B) Phosphorus-based flame retardants, and

[0168] (C) Zinc compounds,

[0169] (A) The resin contains:

[0170] (A-1) Polyphenylene ether resin,

[0171] (A-2) Polystyrene resins, and

[0172] (A-3) Resins containing carbon-carbon unsaturated double bonds,

[0173] The composition contains 0.05 to 5.0 moles of zinc per 1 mole of unsaturated double bonds in the base resin composition.

[0174] According to the above-described method for manufacturing resin foam, it is possible to manufacture resin foam with excellent formability and flame retardancy, even when multiple products are molded from a single mold and processed simultaneously.

[0175] <Granulation Process>

[0176] Examples of granulation processes include: a granulation process in which the resin foam of this embodiment is granulated after being mixed using an extruder to produce granules of a base resin composition; and a granulation process in which the granules of the base resin composition obtained by extrusion mixing and / or the welded product of the base resin composition granules generated during extrusion, and the resin blocks discharged from the extruder or die are granulated after being mixed using an extruder to produce granules of a base resin composition.

[0177] In the granulation process, there is no particular limitation on the method for mixing the various components of the base resin composition. For example, it can be the same as the method described in the above [method for manufacturing base resin composition], and the mixing temperature can also be the same.

[0178] In the granulation process, there is no particular limitation on the granulation method of the extruded base resin composition. For example, it can be the same as the method described in the above [method for manufacturing base resin composition granules], and the water pressure, temperature and other conditions of the circulating water can also be the same when using the underwater cutting method.

[0179] <Immersion Process>

[0180] In the impregnation process, there is no particular limitation on the method for containing a foaming agent in the substrate resin composition, and commonly used methods can be applied. Examples of methods for containing a foaming agent include: methods using a suspension system such as water in an aqueous medium (suspension impregnation); methods using thermally decomposable foaming agents such as sodium bicarbonate (foaming agent decomposition method); methods that bring a gas into a liquid state under an atmosphere above the critical pressure and then contact it with the substrate resin composition (liquid phase impregnation); methods that bring a gas into contact with the substrate resin composition in a gaseous state under a high-pressure atmosphere below the critical pressure (gas phase impregnation); and so on. Among these, the method of containing a foaming agent in the substrate resin composition is particularly preferred, as a method of performing gas phase impregnation under a high-pressure atmosphere below the critical pressure.

[0181] Compared to suspension impregnation performed at high temperatures, gas-phase impregnation offers better gas solubility in the resin, making it easier to increase the foaming agent content. Therefore, it's easier to achieve high foaming ratios, and the bubble size within the substrate resin composition tends to be more uniform. The foaming agent decomposition method can also be performed at high temperatures, and since not all thermally decomposable foaming agents are converted into gas, the amount of gas generated is relatively reduced. Therefore, gas-phase impregnation has the advantage of more easily increasing the foaming agent content. Furthermore, compared to liquid-phase impregnation, gas-phase impregnation allows for more compact equipment such as pressure-resistant devices and cooling systems, resulting in lower equipment costs.

[0182] The gas phase impregnation conditions are not particularly limited, but the atmospheric pressure is preferably 0.5 to 6.0 MPa, more preferably 2.0 to 4.0 MPa. The atmospheric temperature is preferably 5 to 30°C, more preferably 7 to 20°C. The impregnation time is preferably 2.0 to 6.0 hours, more preferably 2.5 to 4.0 hours. When the atmospheric pressure, atmospheric temperature, and impregnation time are within the above ranges, the dissolution of the gas in the substrate resin composition is easier and more effective. In particular, if the atmospheric temperature is low, there is a tendency for the impregnation amount to increase but the impregnation rate to slow down; if the atmospheric temperature is high, there is a tendency for the impregnation amount to decrease but the impregnation rate to increase. To achieve a balance and effectively dissolve the gas in the substrate resin composition, the above-mentioned atmospheric temperatures are preferred.

[0183] There are no particular limitations on the foaming agent; commonly used gases can be used. Examples include inorganic gases such as air, carbon dioxide, nitrogen, oxygen, ammonia, hydrogen, argon, helium, and neon; fluorinated hydrocarbons such as trichlorofluoromethane (R11), dichlorodifluoromethane (R12), dichlorofluoromethane (R22), tetrachlorodifluoroethane (R112), dichlorofluoroethane (R141b), dichlorofluoroethane (R142b), difluoroethane (R152a), HFC-245fa, HFC-236ea, HFC-245ca, and HFC-225ca; and aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and neopentane. Ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, and tetrahydropyran; ketones such as dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl n-hexyl ketone, ethyl n-propyl ketone, and ethyl n-butyl ketone; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and tert-butanol; carboxylic acid esters such as methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate, and ethyl propionate; chlorinated hydrocarbons such as chloromethane and chloroethane; and so on.

[0184] They can be used individually or in combination of two or more.

[0185] From a flame-retardant perspective, the foaming agent is preferably non-flammable and non-combustible; from a gas safety perspective, inorganic gases are preferred. Furthermore, inorganic gases are less soluble in resins than organic gases such as hydrocarbons, and the gas is easily released from the base resin composition during the foaming process or after molding, thus offering the advantage of superior dimensional stability of the foamed molded body over time. In addition, inorganic gases are less likely to cause resin plasticization due to residual gas and exhibit excellent heat resistance from an earlier stage after molding. Among inorganic gases, carbon dioxide is preferred from the perspectives of resin solubility and ease of handling.

[0186] The amount of foaming agent impregnated is preferably 3 to 13 parts by mass, more preferably 3.5 to 10 parts by mass, relative to 100 parts by mass of resin contained in the base resin composition.

[0187] When the amount of foaming agent is 3 parts by mass or more relative to 100 parts by mass of resin in the base resin composition, a higher foaming ratio can be easily achieved, the deviation of bubble size within the base resin composition can be suppressed, and the deviation of foaming ratio between base resin compositions tends to decrease. When the amount of foaming agent is 13 parts by mass or less relative to 100 parts by mass of resin in the base resin composition, the bubble size will not become too small, the tendency to over-foam can be suppressed, and therefore there is a tendency to easily maintain the independent bubble rate.

[0188] <Fogging Process>

[0189] There is no particular limitation on the foaming method of the foaming particles in the foaming process. For example, the following methods can be cited: a method of releasing the foaming agent (gas, etc.) dissolved in the base resin composition from high pressure to low pressure atmosphere at once; a method of heating the foaming agent (gas, etc.) dissolved in the base resin composition by pressurized steam, hot air, etc.; and so on.

[0190] The heating foaming method is particularly preferred. This is because, compared to methods that involve a sudden release from high-pressure conditions to a low-pressure atmosphere, the bubble size within the substrate resin composition tends to become more uniform.

[0191] Pressurized steam has the advantage of easily controlling the foaming ratio, especially for products with low foaming ratios. This pressurized steam is introduced from the bottom of, for example, a foaming furnace through multiple steam holes, and the resin is stirred using stirring blades, thereby enabling more uniform and efficient foaming of the base resin composition. The stirring blade rotation speed is preferably 20–120 rpm, more preferably 50–90 rpm. If the stirring blade rotation speed is 20 rpm or higher, it is easy to uniformly contact the pressurized steam, thus facilitating foaming control and reducing the likelihood of adhesion or other defects. Conversely, if the stirring blade rotation speed is 120 rpm or lower, the resin foam is less likely to be damaged by the stirring blades during foaming, reducing the likelihood of problems such as a decrease in the independent bubble rate or failure to achieve the desired foaming ratio.

[0192] Furthermore, as a foaming method for the resin foam in the foaming process, a method using high-temperature hot air for heating and foaming (hot air foaming) is preferred. This method is particularly effective when the glass transition temperature of the base resin composition (base resin composition granules) is high. Hot air foaming can be either a batch-type or a continuous method.

[0193] When foaming the resin foam to the desired expansion ratio, the foaming process can be carried out in one stage or in multiple stages such as two or three stages. In the case of multi-stage foaming, it is preferable to pressurize the pre-foamed particles (foamed particles that have not undergone the final stage of foaming) with an inorganic gas before each stage of foaming. The gas used for pressurization is not particularly limited, but inorganic gases are preferred from the perspectives of flame retardancy and gas safety. Examples of inorganic gases include air, carbon dioxide, nitrogen, oxygen, ammonia, hydrogen, argon, helium, and neon. Carbon dioxide and air are preferred from the perspectives of ease of handling and economy, but the process is not limited to these. The pressurization method is also not particularly limited; methods such as filling a pressure vessel with resin pre-foamed material and supplying an inorganic gas to pressurize the vessel can be used as examples.

[0194] In resin foams, if aliphatic hydrocarbon gases remain, the residual gases can cause plasticization of the resin, lowering the glass transition temperature and making it prone to failing to exhibit excellent heat resistance. Furthermore, if aliphatic hydrocarbon gases remain in the foamed resin particles, the gases will slowly dissipate over time, easily leading to dimensional changes in the resulting foamed molded article. Therefore, the residual concentration (content) of the aliphatic hydrocarbon gases is preferably below 1000 ppm by volume.

[0195] To ensure that the residual concentration of aliphatic hydrocarbon gases in the resin foam is below 1000 ppm by volume, this can be achieved, for example, by using inorganic gases as foaming agents or by subjecting the resin foam to a "curing process" that releases the residual gases by placing it under high temperature (e.g., arbitrarily set between 40°C and 80°C) conditions for an extended period.

[0196] It should be noted that, in this specification, the residual concentration of aliphatic hydrocarbon gases refers to the value obtained by dividing the volume of aliphatic hydrocarbon gases contained in the resin foam by the volume of the foam (volume ppm). 1 volume ppm (hereinafter also referred to as "ppm") is equivalent to 0.0001 volume.

[0197] (Foam-molded body)

[0198] The foamed molded body of this embodiment is preferably composed of the resin foam of this embodiment. Alternatively, the foamed molded body may also be a molded body obtained by adding a foaming agent to a base resin composition or base resin composition granules and causing it to foam.

[0199] Other foamed molded articles in this embodiment are manufactured using the above-mentioned base resin composition or base resin composition granules with good formability and foaming properties, and therefore have excellent flame retardancy and appearance.

[0200] The preferred expansion ratio of the foamed molded body in this embodiment is 3 to 50 cm³. 3 / g, more preferably 5-15cm 3 / g, further preferably 9-12cm 3 / g. If the foaming ratio of other foamed molded articles is 50cm³. 3 Below a certain value (e.g.), it tends to exhibit excellent heat resistance, mechanical properties, and appearance. If the foaming ratio of other foamed molded parts is 3cm³, then... 3 If the weight is above / g, it tends to fully achieve the goal of lightweighting components.

[0201] It should be noted that the foaming ratio is obtained as follows: after measuring the weight W (g) of the resin foam, the volume V (cc) is measured using water. The volume is then divided by the weight, and the resulting value is the foaming ratio.

[0202] In this embodiment, the independent bubble rate of the foamed molded article is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. If the independent bubble rate of the foamed molded article is 80% or more, it tends to exhibit excellent heat resistance, mechanical properties, and appearance.

[0203] The independent bubble ratio of a foamed molded body can be determined using the same method as that used for resin foams.

[0204] -Manufacturing method of foamed molded body-

[0205] Furthermore, the method for manufacturing the foamed molded article includes a molding step using the resin foam of this embodiment. There are no particular limitations on the method for molding the foamed article using the resin foam; for example, the following method can be used: filling the molding cavity of a molding mold with the resin foam, heating it to cause expansion while simultaneously thermally fusing the resin foam pieces together, and then cooling to solidify the product, thus performing molding. There are no particular limitations on the method of filling the resin foam; known methods can be used.

[0206] Before filling the molding cavity of the molding die into the resin foam, it is preferable to subject the resin foam to gas-based pressurization. By applying a certain gas pressure to the bubbles in the resin foam, the resin foams constituting the foamed molded body are firmly fused together, which improves the rigidity and appearance of the foamed molded body. There are no particular limitations on the gas used for pressurization, but air and inorganic gases are preferred from the perspectives of ease of processing and economy. There are no particular limitations on the pressurization method, and examples include filling the resin foam into a pressurization container, then introducing pressurized gas, increasing the pressure to a maximum pressure of 0.1 to 20 MPa over 10 minutes to 96 hours, thereby supplying gas into the pressurization container; etc.

[0207] Heating methods during the molding of foamed molded articles can include heating using a heat medium such as steam, heating using a heater such as an IR heater, and heating using microwaves. When using a heat medium, a general heat medium can be used, but steam is preferred from the perspective of effectively heating the resin.

[0208] Steam foaming molding methods typically include the following steps: a process of replacing air between foam particles within the mold with steam, referred to as one-sided / opposite-sided heating, using a mold with steam vents; a process of introducing steam from both sides of the mold, referred to as two-sided heating, to fully heat the resin foam and fuse it together; a cooling process of blowing water to cool the heated product; and so on. The temperature is most prone to rise in the two-sided heating process, therefore, residual stress in the foamed mold can be controlled by controlling the temperature and time of the two-sided heating process.

[0209] If the heating temperature of the resin foam is high, the resin foam particles are more likely to fuse together, which easily reduces the residual stress of the foamed molded body, thus tending to improve moldability, heat resistance, and appearance. However, if the heating temperature is too high, the foamed molded body tends to shrink and warp. Similarly, if the heating time of the resin foam is long, the resin foam particles are more likely to fuse together, which easily reduces the residual stress of the foamed molded body, thus tending to improve moldability, heat resistance, and appearance. However, if the heating time is too long, the foamed molded body will shrink, warp, or experience cycle time deterioration and moldability degradation.

[0210] Based on the above, the heating temperature of the resin foam in the molding process is preferably above Tg-30°C of the base resin composition, which can be above Tg-20°C, above Tg-10°C, above Tg, or even greater than Tg. Furthermore, the heating temperature of the resin foam in the molding process is preferably below Tg+50°C of the base resin composition, which can be below Tg+30°C or below Tg+20°C.

[0211] Furthermore, based on the above aspects, the heating time of the resin foam in the molding process is preferably 10 seconds or more, but can be 20 seconds or more, 40 seconds or more, or greater than 40 seconds. Additionally, the heating time of the resin foam in the molding process is preferably 180 seconds or less, but can be 120 seconds or less, or 90 seconds or less.

[0212] For example, the molding process may include heating at a high temperature above Tg, or heating for a long time above Tg for more than 40 seconds.

[0213] Example

[0214] The present invention will be described in more detail below through embodiments, but the present invention is not limited to any of the embodiments described below.

[0215] The determination and evaluation methods used in the examples and comparative examples are described below.

[0216] <Zinc content>

[0217] Approximately 0.1 g of the sample was accurately weighed into a TFM-made decomposition vessel, and sulfuric acid (Kanto Chemical's Ultrapure-100 ultrapure sulfuric acid) and nitric acid (Kanto Chemical's ultrapure nitric acid (EL grade)) were added. Pressure acid decomposition was performed using a Milestone-General microwave decomposition apparatus. The decomposition solution was brought to a final volume of 50 mL, and the analysis was performed using an Agilent Technologies ICP-MS.

[0218] <Phosphorus content>

[0219] Approximately 0.1 g of the sample was accurately weighed into a TFM-made decomposition vessel, and sulfuric acid (Kanto Chemical's Ultrapure-100 ultrapure sulfuric acid) and nitric acid (Kanto Chemical's ultrapure nitric acid (EL grade)) were added. Pressure acid decomposition was performed using a Milestone-General microwave decomposition apparatus. The decomposition solution was brought to a final volume of 50 mL, and the analysis was performed using an Agilent Technologies ICP-MS.

[0220] <Carbon-carbon unsaturated double bond content>

[0221] 0.7 mL of deuterated chloroform (containing the reference peak TMS, 0.00 ppm) was added to approximately 25 mg of sample and dissolved by heating at 50 °C. The solution was prepared using JEOL-made... 1 512 cumulative measurements were performed using ¹H NMR (ECS400, 400 MHz). The integral values ​​of polystyrene (benzene ring (5H), 6.2–7.5 ppm) and butadiene (double bond (2H), 4.9–6.0 ppm) in polyphenylene ether resins (-CH₃(6H), 2.09 ppm), resins containing double bonds were calculated based on the obtained spectra. Since the integral value of polystyrene overlapped with that of the benzene ring in polyphenylene ether resins, the value obtained by subtracting the integral value of the overlapping signal was used. The amount of carbon-carbon unsaturated double bonds in resins containing carbon-carbon unsaturated double bonds was calculated based on these integral values ​​and the number of protons.

[0222] <Moldability>

[0223] Using various foam molding manufacturing methods, foam molded bodies measuring 150mm × 150mm × 3mm in thickness were manufactured under a crack rate of 10%. The case of obtaining one foam molded body using one mold and one cycle of molding was defined as one piece of workability, and the case of obtaining three molded bodies of the above dimensions using one mold and one cycle of molding was defined as multiple pieces of simultaneous workability. The obtained foam molded bodies were visually inspected, and their appearance was evaluated according to the following criteria.

[0224] A: No defects in appearance were observed on the surface and ends of the foamed molded body.

[0225] B: Unsatisfactory appearance is observed on the surface or ends of the foamed molded body.

[0226] C: Appearance defects were observed on the surface and ends of the foamed molded body. Or, a sheet-like foamed molded body could not be obtained, making appearance assessment impossible.

[0227] <Expansion ratio of resin foam>

[0228] After determining the weight W (g) of the resin foam, the volume V (cc) is determined using a water bath. The volume is divided by the weight, and the resulting value V / W (cc / g) is taken as the foaming ratio.

[0229] <Independent bubble rate of resin foam>

[0230] The true volume (Vxp) of a resin foam with a known expansion ratio (cc / g) was measured using an air comparison hydrometer manufactured by Beckman Co., Ltd., and the independent bubble rate Sp (%) was calculated using the following formula.

[0231] Sp(%)={(Vxp-Wp / ρp) / (Vap-Wp / ρp)}×100

[0232] Vxp: True volume of the resin foam (cm³) 3 )

[0233] Vap: Volume of resin foam (expansion ratio × mass) (cc)

[0234] Wp: Mass of the resin foam (g)

[0235] ρp: Density of the resin composition used as the base material for the resin foam (g / cm³) 3 )

[0236] Flame retardancy

[0237] The flame retardancy was evaluated based on the UL94 vertical burning test according to the US UL standard. The test method is shown below.

[0238] The obtained resin foam was molded into test pieces with a length of 125 mm, a width of 13 mm, and a thickness of 5 mm. Five of these molded pieces were used for evaluation. The test pieces were vertically mounted in the clamp and subjected to two 10-second flame contacts using a 20 mm flame. The combustion behavior was used to determine V-0, V-1, V-2, and unsuitable. The criteria for V-0, V-1, V-2, and unsuitable are as follows.

[0239] V-0: The duration of flaming combustion in the first and second tests was less than 10 seconds. In addition, the total duration of flaming combustion and non-flaming combustion in the second test was less than 30 seconds. Furthermore, the total duration of flaming combustion in the five test pieces was less than 50 seconds. There were no samples that burned to the position of the fixing clamp, and no cotton was ignited due to burning debris.

[0240] V-1: The duration of flaming combustion in the first and second tests was less than 30 seconds. In addition, the total duration of flaming combustion and non-flaming combustion in the second test was less than 60 seconds. Furthermore, the total duration of flaming combustion of the five test pieces was less than 250 seconds. There were no samples that burned to the position of the fixing clamp, and no cotton was ignited due to burning debris.

[0241] V-2: The duration of flaming combustion in the first and second tests was less than 30 seconds. In addition, the total duration of flaming combustion and non-flaming combustion in the second test was less than 60 seconds. Furthermore, the total duration of flaming combustion in the five test pieces was less than 250 seconds. There were no samples that burned to the position of the fixed clamp, and the cotton was ignited due to burning debris.

[0242] Not suitable: Does not meet any of V-0, V-1, or V-2.

[0243] The raw materials used in the examples and comparative examples are described below.

[0244] (A-1) Polyphenylene ether resin-1: Modified polyphenylene ether resin S201A (manufactured by Asahi Kasei Corporation)

[0245] (A-2) Polystyrene Resins-1: General Purpose Polystyrene Resin GP685 (manufactured by PS Japan Co., Ltd.)

[0246] (A-3) Resins with carbon-carbon unsaturated double bonds - 1: Impact-resistant polystyrene resin HIPS 475D (manufactured by PSJapan Co., Ltd.)

[0247] (A-3) Resin with carbon-carbon unsaturated double bonds - 2: Styrene-butadiene copolymer K-Resin (manufactured by INEOSStylorution)

[0248] (B) Phosphorus-based flame retardant-1: Condensed phosphate ester flame retardant CR-741 (manufactured by Daihachi Chemical Co., Ltd.)

[0249] (B) Phosphorus-based flame retardant-2: Rabitle FP-110, a phosphazene-based flame retardant (manufactured by Fushimi Pharmaceutical Co., Ltd.)

[0250] (C) Zinc compound-1: Zinc oxide

[0251] (C) Zinc compound-2: Zinc sulfide

[0252] The following describes the embodiments and comparative examples.

[0253] [Examples 1 and Examples 3-5]

[0254] (A-1) polyphenylene ether resin-1, (A-2) polystyrene resin-1, (A-3) resin with carbon-carbon unsaturated double bonds-1, (B) phosphorus flame retardant-1, (B) phosphorus flame retardant-2, (C) zinc compound-1, and (C) zinc compound-2 were mixed in the proportions shown in Table 1. The mixture was then heated, melt-mixed, and extruded using an extruder to produce granules of the base resin composition. Following the method described in Example 1 of Japanese Patent Application Publication No. 4-372630, the granules of the base resin composition were contained in a pressure-resistant container. After replacing the gas in the container with dry air, carbon dioxide (gas) was injected as a foaming agent. At a pressure of 3.0 MPa and a temperature of 10°C, 7% by weight of carbon dioxide was impregnated into the base resin granules for 3 hours. The granules were then foamed in a foaming furnace while the stirring blades rotated at 77 rpm using pressurized steam to obtain a resin foam. The expansion ratio and independent bubble rate of the obtained resin foam are shown in Table 1. The resin foam was pressurized to 0.4 MPa over 4 hours and then maintained at 0.4 MPa for 8 hours for pressure treatment. It was then filled into an in-mold with steam vents and heated using pressurized steam to cause the resin foam to expand and fuse together. After cooling, it was removed from the mold to obtain the foamed molded body. The results of the determination and evaluation of various physical properties of the foamed molded body are shown in Table 1.

[0255] [Example 2]

[0256] Resin-1 with carbon-carbon unsaturated double bonds (A-3) was changed to resin-2 with carbon-carbon unsaturated double bonds (A-3), and the base resin composition granules, resin foams, and foamed molded articles were obtained in the same manner as in Example 1. The results of the determination and evaluation of various physical properties are shown in Table 1.

[0257] [Example 6]

[0258] After obtaining the base resin composition granules using the same composition as in Example 1, they were fed back into the extruder to obtain the base resin composition granules, resin foam, and foamed molded articles. The results of the determination and evaluation of various physical properties are shown in Table 1.

[0259] [Comparative Example 1]

[0260] Without mixing (C) zinc compound, (A-1) polyphenylene ether resin-1, (A-2) polystyrene resin-1, (A-3) resin-1 with carbon-carbon unsaturated double bonds, and (B) phosphorus flame retardant-1 were mixed in the proportions shown in Table 1. Otherwise, the same as in Example 1, base resin composition granules, resin foams, and foamed molded articles were obtained. The results of various physical property determinations and evaluations are shown in Table 1.

[0261] [Comparative Example 2]

[0262] Resin-1 with carbon-carbon unsaturated double bonds (A-3) was not mixed, and polyphenylene ether resin-1 (A-1), polystyrene resin-1 (A-2), phosphorus flame retardant-1 (B), and zinc compound (C) were mixed in the proportions shown in Table 1. Otherwise, the same as in Example 1, base resin composition granules, resin foams, and foamed molded articles were obtained. The results of various physical property determinations and evaluations are shown in Table 1.

[0263] [Comparative Example 3]

[0264] Without mixing (B) phosphorus-based flame retardant-1, (A-1) polyphenylene ether resin-1, (A-2) polystyrene resin-1, (A-3) resin-1 with carbon-carbon unsaturated double bonds, and (C) zinc compound were mixed in the proportions shown in Table 1. Otherwise, the same as in Example 1, base resin composition granules, resin foams, and foamed molded articles were obtained. The results of various physical property determinations and evaluations are shown in Table 1.

[0265] [Comparative Example 4]

[0266] Except for changing the mixing amount of zinc compound (C) to the proportions shown in Table 1, the substrate resin composition granules, resin foams, and foamed molded articles were obtained in the same manner as in Example 1. The results of the determination and evaluation of various physical properties are shown in Table 1.

[0267]

[0268] As shown in Table 1, if it is the resin foam of the present invention, the moldability is excellent even when multiple parts of multiple products are molded using one mold at the same time, and the flame retardancy is excellent.

[0269] Industrial applicability

[0270] According to the present invention, it is possible to provide a resin foam that can be molded into multiple products using a single mold, and which simultaneously exhibits excellent processing performance and flame retardancy.

Claims

1. A resin foam, which is a resin foam formed by foaming a base resin composition, wherein, The substrate resin composition comprises: (A) Resin, (B) Phosphorus-based flame retardants, and (C) Zinc compounds, The (A) resin comprises: (A-1) Polyphenylene ether resin, (A-2) Polystyrene resins, and (A-3) Resins containing carbon-carbon unsaturated double bonds, Each mole of carbon-carbon unsaturated double bonds in the resin having carbon-carbon unsaturated double bonds (A-3) contains 0.05 to 5.0 moles of zinc.

2. The resin foam as described in claim 1, wherein it is in the shape of beads.

3. The resin foam as described in claim 1 or 2, wherein, The flame retardancy, determined by the UL94 vertical burning test based on UL standards, is V-2 to V-0.

4. The resin foam as described in claim 1 or 2, wherein, The (B) phosphorus-based flame retardant comprises 5 to 25 parts by weight of the (A) resin relative to 100 parts by weight of the (A) resin.

5. The resin foam as described in claim 1 or 2, wherein, The amount of carbon-carbon unsaturated double bonds is 0.001 to 0.2 mol relative to 1 mol of phosphorus contained in the substrate resin composition.

6. The resin foam as described in claim 1 or 2, wherein, Of the 100 parts by weight of the (A) resin, there are 40 to 94 parts by weight of the (A-1) polyphenylene ether resin.

7. The resin foam as described in claim 1 or 2, wherein, Of the 100 parts by weight of the (A) resin, there are 1 to 59 parts by weight of the (A-2) polystyrene-based resin.

8. The resin foam as described in claim 1 or 2, wherein, The (A-3) resin having carbon-carbon unsaturated double bonds comprises structural units derived from styrene, wherein the proportion of structural units derived from styrene is 60% to 99% by mass relative to 100% by mass of the (A-3) resin having carbon-carbon unsaturated double bonds.

9. The resin foam as described in claim 1 or 2, wherein, The (B) phosphorus-based flame retardant is at least one selected from the group consisting of phosphate esters and phosphazene compounds.

10. A method for manufacturing a resin foam, comprising the following steps: In the granulation process, the resin foam described in claim 1 or 2 is granulated after being mixed by an extruder to produce granules of the base resin composition. The impregnation process allows the foaming agent to penetrate into the granules; and The foaming process involves foaming the granules impregnated with the foaming agent to obtain a resin foam.

11. A method for manufacturing a resin foam, comprising the following steps: The granulation process involves granulating the granules of the base resin composition obtained by extrusion mixing and / or the welded parts of the base resin composition granules generated during extrusion, as well as the resin blocks discharged from the extruder or die head, by mixing them in an extruder to produce granules of the base resin composition. The impregnation process allows the foaming agent to penetrate into the granules; and The foaming process involves foaming the granules impregnated with the foaming agent to obtain a resin foam. in, The substrate resin composition comprises: (A) Resin, (B) Phosphorus-based flame retardants, and (C) Zinc compounds, The (A) resin comprises: (A-1) Polyphenylene ether resin, (A-2) Polystyrene resins, and (A-3) Resins containing carbon-carbon unsaturated double bonds, Each mole of carbon-carbon unsaturated double bonds in the resin having carbon-carbon unsaturated double bonds (A-3) contains 0.05 to 5.0 moles of zinc.

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