JP7576933B2 - Flame-retardant styrene-based resin composition and molded article - Google Patents

Description

The present invention relates to a flame-retardant styrene-based resin composition and a molded article containing the flame-retardant styrene-based resin composition.

Styrene-based resins are used in a wide range of applications due to their excellent moldability, dimensional stability, and impact resistance. Among them, polystyrene-based resin compositions imparted with flame retardancy are used in a wide range of applications, including home appliances and office automation equipment, and there is currently a demand for thinner products in order to reduce or lighten the weight of these products.
Conventionally, various flame retardants have been proposed to impart flame retardancy to styrene resins, and among them, bromine-based flame retardants, which are inexpensive and have a good balance of physical properties, are widely used. However, in recent years, due to the intensifying movement to regulate halogen-containing organic compounds, mainly in Europe, there is an increasing demand for flame-retardant resins and flame-retardant resin compositions that do not contain bromine elements.

As an alternative flame retardant to such bromine-based flame retardants, for example, Patent Document 1 discloses a technique for adding a phosphinate to a thermoplastic polymer. Patent Document 2 discloses a technique for adding a phosphinate to polyphenylene ether and polystyrene.

Japanese Patent Application Publication No. 11-124466 JP 2008-37970 A

Although the above-mentioned Patent Document 1 describes that flame retardancy can be obtained for polystyrene, these flame retardants have poor dispersibility in polystyrene, insufficient flame retardancy, and problems such as reduced impact strength or poor appearance of molded products have been encountered. In addition, Patent Document 2 contains polyphenylene ether, which provides excellent flame retardancy, but has problems with light resistance such as discoloration due to light. Therefore, there is a problem that it is difficult to use for housings for office equipment or home appliances.
Therefore, an object of the present invention is to provide a flame-retardant styrene-based resin composition which exhibits high flame retardancy and is excellent in impact resistance, light resistance and molded appearance, and a molded article containing the flame-retardant styrene-based resin composition.

As a result of intensive research to solve the above problems, the present inventors have discovered that a flame-retardant styrene-based resin composition containing a rubber-modified styrene-based resin (A), a copolymer resin (B) containing a styrene-based monomer unit (b1), an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit, and a phosphinate salt (C) in specific ratios surprisingly exhibits very high flame retardancy, excellent impact resistance, light resistance, and low dielectric properties, and have completed the present invention.

［上記式（１）中、Ｒ¹¹及びＲ¹²は、各々独立して、直鎖状若しくは分岐状の炭素原子数１～６のアルキル基又は炭素原子数６～１０のアリール基であり；Ｍ¹は、カルシウムイオン、マグネシウムイオン、アルミニウムイオン、亜鉛イオン、ビスマスイオン、マンガンイオン、ナトリウムイオン、カリウムイオン及びプロトン化された窒素塩基からなる群より選ばれる少なくとも１種であり；ａはＭ¹のイオン価を表し、１～３の整数であり；ｍ¹は、１～３の整数であり；ａ＝ｍ¹である。］で表されるホスフィン酸塩、及び
下記式（２）：

［式中、Ｒ²¹及びＲ²²は、各々独立して、直鎖状若しくは分岐状の炭素原子数１～６のアルキル基又は炭素原子数６～１０のアリール基であり；Ｌ²³は、直鎖状若しくは分岐状の炭素原子数１～１０のアルキレン基、炭素原子数６～１０のアリーレン基、炭素原子数６～１０のアルキルアリーレン基又は炭素原子数６～１０のアリールアルキレン基であり；Ｍ²は、カルシウムイオン、マグネシウムイオン、アルミニウムイオン、亜鉛イオン、ビスマスイオン、マンガンイオン、ナトリウムイオン、カリウムイオン及びプロトン化された窒素塩基からなる群より選ばれる少なくとも１種であり；ｂはＭ²のイオン価を表し、１～３の整数であり；ｍ²は、１～３の整数であり；ｉは、１又は２の整数であり；ｂ×ｉ＝２ｎである］で表されるジホスフィン酸塩からなる群より選ばれる少なくとも１種のホスフィン酸塩類を含む難燃剤（Ｃ）を１０～３０質量％と、
を含有することを特徴とする難燃性スチレン系樹脂組成物。 That is, the present invention is as follows.
[1] 40 to 85% by mass of a rubber-modified styrene-based resin (A),
a copolymer resin (B) containing a styrene-based monomer unit (b1), an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit in an amount of 5.0 to 30% by mass;
The following general formula (1):

[In the above formula (1), R ¹¹ and R ¹² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms; M ¹ is at least one selected from the group consisting of calcium ion, magnesium ion, aluminum ion, zinc ion, bismuth ion, manganese ion, sodium ion, potassium ion, and protonated nitrogen base; a represents the ionic valence of M ¹ and is an integer of 1 to 3; m ¹ is an integer of 1 to 3; and a=m ^1. ], and a phosphinic acid salt represented by the following formula (2):

[wherein R ²¹ and R ²² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms; L ²³ is a linear or branched alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 10 carbon atoms, an alkylarylene group having 6 to 10 carbon atoms, or an arylalkylene group having 6 to 10 carbon atoms; M ² is at least one selected from the group consisting of calcium ions, magnesium ions, aluminum ions, zinc ions, bismuth ions, manganese ions, sodium ions, potassium ions, and protonated nitrogen bases; b represents the ionic valence of M ² and is an integer of 1 to 3; m ² is an integer of 1 to 3; i is an integer of 1 or 2; and b×i=2n],
A flame-retardant styrene-based resin composition comprising:

[2] The flame-retardant styrene-based resin composition according to [1], in which the copolymer resin (B) contains 67.0 to 96.0% by mass of the styrene-based monomer units (b1), 4.0 to 18.0% by mass of the unsaturated carboxylic acid-based monomer units, and 0.0 to 15.0% by mass of the unsaturated carboxylic acid ester-based monomer units, when the total content of the styrene-based monomer units, the unsaturated carboxylic acid ester-based monomer units, and the unsaturated carboxylic acid ester-based monomer units is taken as 100% by mass.

[3] The flame-retardant styrene-based resin composition according to claim 1 or 2, wherein the flame retardant (C) is granular and has an average particle size of more than 0.5 μm and not more than 10 μm.

[4] A molded article comprising the flame-retardant styrene-based resin composition described in any one of [1] to [3] above.

The present invention provides a flame-retardant styrene-based resin composition that exhibits high flame retardancy and is excellent in impact resistance, light resistance, and molded appearance, as well as a molded article that contains the flame-retardant styrene-based resin composition.

The following describes in detail an embodiment of the present invention (hereinafter referred to as the "present embodiment"); however, the present invention is not limited to the following description, and can be practiced in various modifications within the scope of the gist of the invention.

[Flame-retardant styrene-based resin composition]
The flame-retardant styrene-based resin composition of the present embodiment contains 40 to 85 mass % of a rubber-modified styrene-based resin (A), 5.0 to 30 mass % of a copolymer resin (B) containing a styrene-based monomer unit (b1), an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit, and a flame retardant (C) containing a phosphinate having a specific chemical structure.

<Rubber-modified styrene-based resin (A): Component (A)>
The flame-retardant styrene-based resin composition of the present embodiment uses a rubber-modified styrene-based resin (A) in order to increase impact strength. The content of the rubber-modified styrene-based resin (A) is 40 to 85 mass%, preferably 50 to 80 mass%, and more preferably 55 to 75 mass%, based on 100 mass% of the flame-retardant styrene-based resin composition. If it exceeds 85 mass%, the flame retardancy decreases.

The rubber-modified styrene-based resin (A) of this embodiment is a styrene-based resin matrix in which particles of a rubber-like polymer (a1) are dispersed, and can be produced by polymerizing a styrene-based monomer in the presence of the rubber-like polymer (a1).

In addition to styrene, examples of the styrene monomer (a2) contained in the styrene resin that is the matrix constituting the rubber-modified styrene resin (A) of this embodiment include α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and t-butylstyrene, or bromostyrene, chlorostyrene, and indene. Styrene is particularly preferred. One or more of these styrene monomers can be used.

The rubber-like polymer (a1) contained in the rubber-modified styrene-based resin (A) of this embodiment may contain a styrene-based resin on the inside (including a salami structure and a core-shell structure) and have a styrene-based resin grafted on the outside.

As the rubber-like polymer (a1), for example, polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. can be used, but polybutadiene or styrene-butadiene copolymer is preferred. As the polybutadiene, both high-cis polybutadiene with a high cis content and low-cis polybutadiene with a low cis content can be used. In addition, as the structure of the styrene-butadiene copolymer, both a random structure and a block structure can be used. These rubber-like polymers (a1) can be used alone or in combination. In addition, saturated rubber obtained by hydrogenating butadiene rubber can also be used.

Examples of such rubber-modified styrene-based resins (A) include HIPS (high impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), and AES resin (acrylonitrile-ethylene propylene rubber-styrene copolymer).

When the rubber-modified styrene-based resin (A) is a HIPS-based resin, the particularly preferred rubber-like polymer (a1) is a high-cis polybutadiene having 90 mol % or more of cis-1,4 bonds, preferably having 6 mol % or less of vinyl-1,2 bonds, and more preferably having 3 mol % or less of vinyl-1,2 bonds.
The content of isomers having a cis-1,4, trans-1,4, or vinyl-1,2 structure as a constituent unit of the high-cis polybutadiene can be measured using an infrared spectrophotometer and calculated by processing the data according to the Morello method.
The high-cis polybutadiene can be easily obtained by a known production method, for example, by polymerizing 1,3-butadiene using a catalyst containing an organoaluminum compound and a cobalt or nickel compound.

The content of the rubber-like polymer (a1) in the rubber-modified styrene-based resin (A) is preferably 3 to 20% by mass, more preferably 5 to 20% by mass. If the content of the rubber-like polymer (a1) is less than 3% by mass, the impact resistance of the styrene-based resin decreases. If the content of the rubber-like polymer (a1) is more than 20% by mass, the flame retardancy decreases.
In the present disclosure, the content of the rubber-like polymer (a1) contained in the rubber-modified styrene-based resin (A) is a value calculated using pyrolysis gas chromatography.

The average particle size of the rubber-like polymer (a1) contained in the rubber-modified styrene-based resin (A) is preferably 0.5 to 4.0 μm, more preferably 0.8 to 3.5 μm, from the viewpoints of impact resistance and flame retardancy.
In the present disclosure, the average particle size of the rubber-like polymer (a1) contained in the rubber-modified styrene-based resin (A) is a value measured by the procedure described in the section [Examples] below.

The reduced viscosity of the rubber-modified styrene-based resin (A), which is an index of the molecular weight of the rubber-modified styrene-based resin (A), is preferably in the range of 0.50 to 0.85 dL/g, more preferably in the range of 0.55 to 0.80 dL/g. If it is less than 0.50 dL/g, the impact strength decreases, and if it exceeds 0.85 dL/g, the moldability decreases due to the decrease in fluidity.
In the present disclosure, the reduced viscosity of the rubber-modified styrene-based resin (A) is a value measured in a toluene solution at 30° C. and a concentration of 0.5 g/dL, and more specifically, is a value measured by the procedure described in the section [Examples] below.

The method for producing the rubber-modified styrene-based resin (A) is not particularly limited, but it can be produced by bulk polymerization (or solution polymerization) in which a styrene-based monomer (and a solvent) is polymerized in the presence of the rubber-like polymer (a1), or by bulk-suspension polymerization in which the reaction transitions to suspension polymerization during the course of the reaction, or by emulsion graft polymerization in which a styrene-based monomer is polymerized in the presence of the rubber-like polymer (a1) latex. In bulk polymerization, the rubber-like polymer (a1) can be produced by continuously supplying a mixed solution containing the rubber-like polymer (a1) and the styrene-based monomer (a2), and optionally an organic solvent, an organic peroxide, and/or a chain transfer agent, to a polymerization apparatus consisting of a complete mixing reactor or a tank reactor and multiple tank reactors connected in series.

<Copolymer resin (B): (B) component>
In the present embodiment, the content of the copolymer resin (B) containing the styrene-based monomer unit (b1), the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit is, The content is 5 to 30% by mass, preferably 8 to 25% by mass, and more preferably 10 to 20% by mass, based on 100% by mass of the flame-retardant styrene-based resin composition. If the content is too low, the dispersibility of the flame retardant (c) is insufficient, resulting in a decrease in impact strength and molded appearance, whereas if the content is more than 30 mass %, the impact strength decreases.

In the copolymer resin (B), when the total content of the styrene-based monomer unit (b1), the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit is taken as 100% by mass, the content of the styrene-based monomer unit (b1) is preferably 67.0 to 96.0% by mass, more preferably 74.0 to 92.0% by mass, and even more preferably 77.0 to 87.0% by mass. By making the content 67.0% by mass or more, the fluidity of the resin can be improved, while by making the content 96.0% by mass or less, the unsaturated carboxylic acid-based monomer unit and the unsaturated carboxylic acid ester-based monomer unit described below are present in desired amounts, and the effects described below due to these monomer units are expressed.

In the flame-retardant styrene-based resin composition of this embodiment, the unsaturated carboxylic acid-based monomer unit plays a role in improving heat resistance. In the copolymer resin (B), when the total content of the styrene-based monomer unit (b1), the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit is taken as 100% by mass, the content of the unsaturated carboxylic acid-based monomer unit is preferably 4.0 to 18.0% by mass, more preferably 6.0 to 16.0% by mass, and even more preferably 8.0 to 13.0% by mass. By making the content 4.0% by mass or more, it is possible to further improve heat resistance, while by making the content 18.0% by mass or less, it is possible to develop high flame retardancy and also improve the fluidity and mechanical properties of the resin.

Generally, styrene-methacrylic acid resins, including styrene-methacrylic acid-methyl methacrylate copolymer resins, are almost always produced on an industrial scale by radical polymerization, but in order to suppress the gelling reaction during the devolatilization process, various alcohols may be added to the polymerization system before polymerization.

In the present embodiment, the unsaturated carboxylic acid ester monomer can be used to suppress the dehydration reaction of the unsaturated carboxylic acid monomer through intermolecular interaction with the unsaturated carboxylic acid monomer, and to improve the mechanical strength of the resin. Furthermore, the unsaturated carboxylic acid ester monomer also contributes to improving resin properties such as weather resistance and surface hardness.
In the copolymer resin (B), when the total content of the styrene monomer unit (b1), the unsaturated carboxylic acid monomer unit, and the unsaturated carboxylic acid ester monomer unit is taken as 100% by mass, the content of the unsaturated carboxylic acid ester monomer unit is preferably 0 to 15% by mass, more preferably 1 to 12% by mass, and even more preferably 2 to 10% by mass. By making the content 15% by mass or less, the fluidity of the resin can be improved and water absorption can be suppressed. In addition, by making the content of the unsaturated carboxylic acid ester monomer unit 0% by mass, the heat resistance can be improved and the cost can be reduced, but from the above viewpoint, the content of the unsaturated carboxylic acid ester monomer unit can also be made to be more than 0% by mass.

In addition, when unsaturated carboxylic acid monomer units and unsaturated carboxylic acid ester monomer units are bonded side by side, if a high-temperature, high-vacuum devolatilizer is used, a dealcoholization reaction may occur under certain conditions, resulting in the formation of a six-membered cyclic acid anhydride. The copolymer resin (B) of this embodiment may contain this six-membered cyclic acid anhydride, but it is preferable to contain as little as possible, as this reduces fluidity.

In this embodiment, the contents of the styrene monomer unit (b1), the unsaturated carboxylic acid monomer unit (e.g., methacrylic acid monomer unit) and the unsaturated carboxylic acid ester monomer unit (e.g., methyl methacrylate monomer unit) in the copolymer resin (B) can be determined from the integral ratio of the spectrum measured by a proton nuclear magnetic resonance ( ¹ H-NMR) measurement device. The contents of each monomer unit in the copolymer resin (B) described later can also be determined by proton nuclear magnetic resonance measurement.

In this embodiment, the copolymer resin (B) typically consists of a styrene-based monomer unit (b1), an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit, although it is not excluded that the copolymer resin (B) may further contain monomer units other than the styrene-based monomer unit (b1), the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit, within a range that does not impair the effects of the present invention.

The styrene-based monomer (b1) is not particularly limited, but examples thereof include styrene derivatives such as styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, t-butylstyrene, bromostyrene, chlorostyrene, and indene. From an industrial viewpoint, styrene is preferred as the styrene-based monomer (b1). These styrene-based monomers (b1) can be used alone or in combination of two or more.

The unsaturated carboxylic acid monomer is not particularly limited, but examples thereof include methacrylic acid, acrylic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, and the like. As the unsaturated carboxylic acid monomer, methacrylic acid is preferred because it has a large effect of improving heat resistance, is liquid at room temperature, and has excellent handleability. These unsaturated carboxylic acid monomers can be used alone or in combination of two or more.

Furthermore, the above-mentioned unsaturated carboxylic acid ester monomer is not particularly limited, but examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. As the (meth)acrylic acid ester monomer, methyl (meth)acrylate is preferred because it has a small effect on the decrease in heat resistance. These unsaturated carboxylic acid ester monomers can be used alone or in combination of two or more.

In this embodiment, the weight average molecular weight (Mw) of the copolymer resin (B) is preferably 100,000 to 350,000, more preferably 120,000 to 300,000, and even more preferably 140,000 to 240,000. When the weight average molecular weight (Mw) is 100,000 to 350,000, a resin with a better balance between mechanical strength and fluidity is obtained, and there is also little gel contamination. The weight average molecular weight (Mw) is a value obtained by using gel permeation chromatography and converting it into standard polystyrene.

In this embodiment, the melt flow rate of the copolymer resin (B) is preferably 0.3 to 3.0 g/10 min, more preferably 0.4 to 2.5 g/10 min, and even more preferably 0.4 to 2.0 g/10 min. A melt flow rate of 0.3 g/10 min or more is preferable from the viewpoint of fluidity, and a melt flow rate of 3.0 g/10 min or less is preferable from the viewpoint of mechanical strength of the resin. The melt flow rate is a value measured at 200°C and a load of 49 N in accordance with ISO 1133.

In the present embodiment, the polymerization method for the copolymer resin (B) is not particularly limited, but for example, a bulk polymerization method or a solution polymerization method can be suitably adopted as a radical polymerization method. The polymerization method mainly includes a polymerization step of polymerizing the polymerization raw materials (monomer components) and a devolatilization step of removing volatile matters such as unreacted monomers and polymerization solvent from the polymerization product.
Hereinafter, a polymerization method for the copolymer resin (B) that can be used in the present embodiment will be described.

When the polymerization raw materials are polymerized to obtain the copolymer resin (B), the polymerization raw material composition typically contains a polymerization initiator and a chain transfer agent. Examples of the polymerization initiator include organic peroxides, such as peroxyketals such as 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, and n-butyl-4,4-bis(t-butylperoxy)valerate, dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, and dicumyl peroxide, diacyl peroxides such as acetyl peroxide and isobutyryl peroxide, peroxydicarbonates such as diisopropyl peroxydicarbonate, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, and hydroperoxides such as t-butyl hydroperoxide. From the viewpoint of decomposition rate and polymerization rate, 1,1-bis(t-butylperoxy)cyclohexane is preferred.

Examples of the chain transfer agent include α-methylstyrene linear dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan.

As a polymerization method for the copolymer resin (B), solution polymerization using a polymerization solvent can be adopted as necessary. Examples of polymerization solvents used include aromatic hydrocarbons, such as ethylbenzene, and dialkyl ketones, such as methyl ethyl ketone, and each of these may be used alone or in combination of two or more. Other polymerization solvents, such as aliphatic hydrocarbons, can be further mixed with the aromatic hydrocarbons as long as the solubility of the polymerization product is not reduced. These polymerization solvents are preferably used in an amount not exceeding 25 parts by mass per 100 parts by mass of the total monomers. If the amount of polymerization solvent exceeds 25 parts by mass per 100 parts by mass of the total monomers, the polymerization rate is significantly reduced and the mechanical strength of the obtained resin tends to be significantly reduced. It is preferable to add 5 to 20 parts by mass per 100 parts by mass of the total monomers before polymerization, as this makes it easier to uniformize the quality and is also preferable in terms of polymerization temperature control.

In this embodiment, the apparatus used in the polymerization step to obtain the copolymer resin (B) is not particularly limited, and may be appropriately selected according to the polymerization method of the styrene-based resin. For example, in the case of bulk polymerization, a polymerization apparatus having one or more completely mixed reactors connected together can be used. There is also no particular limit to the devolatilization step. In the case of bulk polymerization, the polymerization is continued until the unreacted monomer is preferably 50% by mass or less, more preferably 40% by mass or less, and the devolatilization treatment is performed by a known method to remove the volatile matter such as the unreacted monomer. For example, a normal devolatilization apparatus such as a flash drum, a twin-screw devolatilizer, a thin film evaporator, or an extruder can be used, but a devolatilization apparatus with a small retention portion is preferred. The temperature of the devolatilization treatment is usually about 190 to 280°C, and from the viewpoint of suppressing the formation of a six-membered ring acid anhydride due to the adjacent methacrylic acid and methyl methacrylate, 190 to 260°C is more preferred. The pressure for the devolatilization process is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, and more preferably 0.13 to 2.0 kPa. Desirable devolatilization methods include, for example, a method of removing volatiles by reducing pressure under heating, and a method of removing volatiles through an extruder or the like designed for the purpose of removing volatiles.

<Flame Retardant (C): Component (C)>
The flame-retardant styrene-based resin composition of the present embodiment contains 10 to 30 mass% of the flame retardant (C) relative to 100 mass% of the flame-retardant styrene-based resin composition, preferably 11 to 29 mass%, more preferably 12 to 28 mass%, and even more preferably 15 to 25 mass%.
In this embodiment, the flame retardant (C) contains at least one phosphinate selected from silver phosphinates and diphosphinates, and preferably contains 70 mass% or more of the phosphinates relative to the entire flame retardant (C) (100 mass%). Therefore, the flame retardant (C) in this embodiment may contain 30 mass% or less of a known flame retardant other than the phosphinates relative to the entire flame retardant (C) (100 mass%).

［上記式（１）中、Ｒ¹¹及びＲ¹²は、各々独立して、直鎖状若しくは分岐状の炭素原子数１～６のアルキル基又は炭素原子数６～１０のアリール基であり；Ｍ¹は、カルシウムイオン、マグネシウムイオン、アルミニウムイオン、亜鉛イオン、ビスマスイオン、マンガンイオン、ナトリウムイオン、カリウムイオン及びプロトン化された窒素塩基からなる群より選ばれる少なくとも１種であり；ａはＭ¹のイオン価を表し、１～３の整数であり；ｍ¹は、１～３の整数であり；ａ＝ｍ¹である。Ｒ¹¹及びＲ¹²がそれぞれ複数存在する場合は、それぞれのＲ¹¹及びＲ¹²が同一であってもあるいは異なっていてもよい。］ In this embodiment, the phosphinate is represented by the following general formula (1).

[In the above formula (1), R ¹¹ and R ¹² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms; M ¹ is at least one selected from the group consisting of calcium ion, magnesium ion, aluminum ion, zinc ion, bismuth ion, manganese ion, sodium ion, potassium ion, and protonated nitrogen base; a represents the ionic valence of M ¹ and is an integer of 1 to 3; m ¹ is an integer of 1 to 3; a=m ^1. When there are a plurality of R ¹¹ and R ¹² , each R ¹¹ and R ¹² may be the same or different.]

［上記式（２）中、Ｒ²¹及びＲ²²は、各々独立して、直鎖状若しくは分岐状の炭素原子数１～６のアルキル基又は炭素原子数６～１０のアリール基であり；Ｌ²³は、直鎖状若しくは分岐状の炭素原子数１～１０のアルキレン基、炭素原子数６～１０のアリーレン基、炭素原子数６～１０のアルキルアリーレン基又は炭素原子数６～１０のアリールアルキレン基であり；Ｍ²は、カルシウムイオン、マグネシウムイオン、アルミニウムイオン、亜鉛イオン、ビスマスイオン、マンガンイオン、ナトリウムイオン、カリウムイオン及びプロトン化された窒素塩基からなる群より選ばれる少なくとも１種であり；ｂはＭ²のイオン価を表し、１～３の整数であり；ｍ²は、１～３の整数であり；ｉは、１又は２の整数であり；ｂ×ｉ＝２ｍ²である。Ｒ²¹及びＲ¹²がそれぞれ複数存在する場合は、それぞれのＲ²¹及びＲ²²が同一であってもあるいは異なっていてもよい。］からなる群より選ばれる少なくとも１種が挙げられる。 In this embodiment, the diphosphinate is represented by the following general formula (2).

[In the above formula (2), R ²¹ and R ²² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms; L ²³ is a linear or branched alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 10 carbon atoms, an alkylarylene group having 6 to 10 carbon atoms, or an arylalkylene group having 6 to 10 carbon atoms; M ² is at least one selected from the group consisting of calcium ion, magnesium ion, aluminum ion, zinc ion, bismuth ion, manganese ion, sodium ion, potassium ion, and protonated nitrogen base; b represents the ionic valence of M ² and is an integer of 1 to 3; m ² is an integer of 1 to 3; i is an integer of 1 or 2; b×i=2m ^2. When there are a plurality of ^{R 21} and R ¹² , each R ²¹ and R ²² may be the same or different. At least one selected from the group consisting of:

Examples of linear or branched alkyl groups having 1 to 6 carbon atoms include linear alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, or a hexyl group, and branched alkyl groups such as an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, an isoamyl group, or a t-amyl group.
The aryl group having 6 to 10 carbon atoms may have a single ring structure or a condensed ring structure, and examples thereof include a phenyl group and a naphthyl group.
Examples of the linear or branched alkylene group having 1 to 10 carbon atoms include groups in which one hydrogen atom has been removed from the linear or branched alkyl group having 1 to 6 carbon atoms.
Examples of the arylene group having 6 to 10 carbon atoms include groups in which one hydrogen atom has been removed from the above-mentioned aryl group having 6 to 10 carbon atoms.
Examples of the alkylarylene group having 6 to 10 carbon atoms include a methylphenylene group, an ethylphenylene group, a tert-butylphenylene group, a methylnaphthylene group, an ethylnaphthylene group, and a tert-butylnaphthylene group.
Examples of the arylalkylene group having 6 to 10 carbon atoms include a phenylmethylene group, a phenylethylene group, a phenylpropylene group, and a phenylbutylene group.
In the above formula (1), it is preferable that R ¹¹ and R ¹² each independently represent a linear alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.
In the above formula (1), M ¹ is preferably calcium, magnesium, aluminum, or zinc. Also, a represents the ionic valence of M ¹ and is 2 or 3.
In the above formula (2), it is preferable that R ²¹ and R ²² are each independently a linear alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.
In the above formula (2), it is preferable that each L ²³ is independently a linear alkylene group having 1 to 6 carbon atoms or an arylene group having 6 to 10 carbon atoms.
In the above formula (2), ^M2 is preferably calcium, magnesium, aluminum, or zinc. Also, b represents the ionic valence of ^M2 and is 2 or 3.
Phosphinates have excellent electrical properties, making them suitable for flame-retardant materials that require insulation. They also have excellent hydrolysis properties, making them suitable for use in high-temperature, high-humidity environments, and are highly recyclable.

The phosphinates used in this embodiment are produced in aqueous solution using, among others, phosphinic acid and a metal carbonate, metal hydroxide or metal oxide, and are essentially monomeric compounds, but also include polymeric phosphinates with a degree of condensation of 1 to 3 in some circumstances, depending on the reaction conditions.

Such phosphinates are not particularly limited, and examples thereof include calcium dimethylphosphinate, magnesium dimethylphosphinate, aluminum dimethylphosphinate, zinc dimethylphosphinate, calcium ethylmethylphosphinate, magnesium ethylmethylphosphinate, aluminum ethylmethylphosphinate, zinc ethylmethylphosphinate, calcium diethylphosphinate, magnesium diethylphosphinate, aluminum diethylphosphinate, zinc diethylphosphinate, calcium methyl-n-propylphosphinate, magnesium methyl-n-propylphosphinate, aluminum methyl-n-propylphosphinate, zinc methyl-n-propylphosphinate, calcium methane di(methylphosphinate), magnesium methane di(methylphosphinate), aluminum methane di(methylphosphinate), zinc methane di(methylphosphinate), calcium benzene-1,4-(dimethylphosphinate), benzene-1,4- Examples of the methylphenylphosphinate include magnesium (dimethylphosphinate), aluminum benzene-1,4-(dimethylphosphinate), zinc benzene-1,4-(dimethylphosphinate), calcium methylphenylphosphinate, magnesium methylphenylphosphinate, aluminum methylphenylphosphinate, zinc methylphenylphosphinate, calcium diphenylphosphinate, magnesium diphenylphosphinate, aluminum diphenylphosphinate, and zinc diphenylphosphinate. Of these, calcium dimethylphosphinate, aluminum dimethylphosphinate, zinc dimethylphosphinate, calcium ethylmethylphosphinate, aluminum ethylmethylphosphinate, aluminum ethylbutylphosphinate, aluminum dibutylphosphinate, zinc ethylmethylphosphinate, calcium diethylphosphinate, aluminum diethylphosphinate, and zinc diethylphosphinate are preferred, and aluminum diethylphosphinate is more preferred.
Commercially available phosphinates include, but are not limited to, Exolit (registered trademark) OP1230, OP1240, OP1311, OP1312, OP930, and OP935 manufactured by Clariant Japan KK

In this embodiment, the phosphinate is preferably granular. When the phosphinate is granular, the average particle size of the phosphinate is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less, from the viewpoint of improving the mechanical strength and appearance of the molded article obtained by molding the flame-retardant resin composition of this embodiment, and it is preferable to use a powder of the phosphinate pulverized to this particle size. It is preferably more than 0.5 to 10 μm, more preferably more than 1 μm to 10 μm. When a powder with a preferred particle size is used, not only high flame retardancy is exhibited, but also impact strength is significantly increased, which is particularly preferable.
The method for measuring the average particle size of granular phosphinates is based on the volumetric particle size measured using a laser diffraction/scattering particle size distribution measuring device. The value is measured using a 3% isopropanol aqueous solution as the dispersion medium for the phosphinates. Specifically, the average particle size can be determined by performing a blank measurement using a laser diffraction/scattering particle size distribution measuring device LA-910 (manufactured by Horiba, Ltd.) with a dispersion medium of 3% isopropanol aqueous solution, and then inserting a measurement sample so that the measurement sample has a specified transmittance (95% to 70%). The sample is dispersed in the dispersion medium by irradiating it with ultrasonic waves for 1 minute.

<Optionally Added Ingredients>
In addition to the above components (A) to (C), the flame-retardant styrene-based resin composition of the present embodiment may contain optional additives such as conventionally known additives and processing aids, as necessary, within the scope of not impairing the effects of the present invention. Examples of such additives and processing aids include antioxidants, weathering agents, lubricants, antistatic agents, fillers, and flame-retardant aids (fluorine-based resins, such as polytetrafluoroethylene or PS-coated PTFE containing 50% polytetrafluoroethylene).

Examples of the antioxidant in this embodiment include phenol-based compounds, phosphorus-based compounds, and thioether-based compounds.
Examples of the phenol-based antioxidants include 2,6-di-tert-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, distearyl (3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate, 1,6-hexamethylenebis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid amide], 4,4'-thiobis(6-tert-butyl-m-cresol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(6-tert-butyl -m-cresol), 2,2'-ethylidenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis(4-sec-butyl-6-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 2-tert-butyl- 4-Methyl-6-(2-acryloyloxy-3-tert-butyl-5-methylbenzyl)phenol, stearyl[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)methylpropionate]methane, thiodiethylene glycol bis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,6-hexamethylene bis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis[3,3-bis(4-hydroxy-3-tert-butylphenyl)butyric acid ] glycol ester, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl]terephthalate, 1,3,5-tris[(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, 3,9-bis[1,1-dimethyl-2-{(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, triethylene glycol bis[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], etc. These may be used in combination of two or more kinds.

Examples of the phosphorus-based antioxidants include tris(2,4-di-tert-butylphenyl)phosphite, trisnonylphenyl phosphite, tris[2-tert-butyl-4-(3-tert-butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl]phosphite, tridecyl phosphite, octyldiphenyl phosphite, di(decyl)monophenyl phosphite, di(tridecyl)pentaerythritol diphosphite, and di(nonylphenyl)pentaerythritol. tet diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, tetra(tridecyl)isopropylidenediphenol diphosphite, tetra(tridecyl)-4,4'-n -butylidenebis(2-tert-butyl-5-methylphenol)diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, tetrakis(2,4-di-tert-butylphenyl)biphenylene diphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 2,2'-methylenebis(4,6-tert-butylphenyl)-2-ethylhexylphosphine phosphite, 2,2'-methylenebis(4,6-tert-butylphenyl)-octadecyl phosphite, 2,2'-ethylidenebis(4,6-di-tert-butylphenyl)fluorophosphite, tris(2-[(2,4,8,10-tetrakis-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]ethyl)amine, phosphite of 2-ethyl-2-butylpropylene glycol and 2,4,6-tri-tert-butylphenol, etc. These may be used in a mixture of two or more kinds.

The above-mentioned thioether-based antioxidants include, for example, dialkyl thiodipropionates such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate, and pentaerythritol tetra(β-alkyl mercaptopropionate esters. Two or more of these may be mixed and used.

The weather resistance agent may be an ultraviolet absorber, a hindered amine light stabilizer, or the like.

Examples of the ultraviolet absorber include 2-hydroxybenzophenones such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 5,5'-methylenebis(2-hydroxy-4-methoxybenzophenone); 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxyphenyl)benzotriazoles such as 2-(2'-hydroxy-5'-tert-octylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-dicumylphenyl)benzotriazole, 2,2'-methylenebis(4-tert-octyl-6-(benzotriazolyl)phenol), and 2-(2'-hydroxy-3'-tert-butyl-5'-carboxyphenyl)benzotriazole; phenyl salicyl benzoates such as 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, 2,4-di-tert-amylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, and hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate; substituted oxanilides such as 2-ethyl-2'-ethoxyoxanilide and 2-ethoxy-4'-dodecyloxanilide; ethyl-α-cyano-β,β-diphenylacrylate; cyanoacrylates such as methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate; and triaryltriazines such as 2-(2-hydroxy-4-octoxyphenyl)-4,6-bis(2,4-di-tert-butylphenyl)-s-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-s-triazine, and 2-(2-hydroxy-4-propoxy-5-methylphenyl)-4,6-bis(2,4-di-tert-butylphenyl)-s-triazine. These may be used in combination of two or more kinds.

Examples of hindered amine light stabilizers include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, and tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate. tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butane tetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidyl)-di(tridecyl)-1,2,3,4-butane tetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-di(tridecyl)-1,2,3,4-butane tetracarboxylate, bis(1,2,2,4,4-pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, 1-(2-hydroxyethyl)-2,2, 6,6-tetramethyl-4-piperidinol/diethyl succinate polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/2,4-dichloro-6-tert-octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8,12-tetraazadodecane, 1 , 5,8,12-tetrakis[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8-12-tetraazadodecane, 1,6,11-tris[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]aminoundecane, and 1,6,11-tris[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazin-6-yl]aminoundecane. These may be used in combination of two or more.

The above lubricants can be fatty amides, fatty esters, fatty acids, fatty acid metal salts, etc.

Examples of the aliphatic amide lubricants include stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, ethylene bisstearic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, and ethylene bislauric acid amide.
These may be used in combination of two or more.

The above-mentioned aliphatic ester-based lubricants include methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, methyl erucate, methyl behenate, butyl laurate, butyl stearate, isopropyl myristate, isopropyl palmitate, octyl palmitate, coconut fatty acid octyl ester, octyl stearate, tallow fatty acid octyl ester, lauryl laurate, stearyl stearate, behenyl behenate, cetyl myristate, esters of linear, unbranched, saturated monocarboxylic acid having 28 to 30 carbon atoms (hereinafter abbreviated as montanic acid) and ethylene glycol, esters of montanic acid and glycerin, ... Examples of such esters include esters of montanic acid and butylene glycol, esters of montanic acid and trimethylolethane, esters of montanic acid and trimethylolpropane, esters of montanic acid and pentaerythritol, glycerin monostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan trioleate. These may be used in combination of two or more kinds.

Specific examples of the saturated fatty acids among the above fatty acid-based lubricants include lauric acid (dodecanoic acid), isodecanoic acid, tridecylic acid, myristic acid (tetradecanoic acid), pentadecylic acid, palmitic acid (hexadecanoic acid), margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), isostearic acid, tuberculostearic acid (nonadecanoic acid), 2-hydroxystearic acid, arachidic acid (icosanoic acid), behenic acid (docosanoic acid), lignoceric acid (tetradocosanoic acid), cerotic acid (hexadocosanoic acid), montanic acid (octadocosanoic acid), and melissic acid, and particularly include lauric acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, and montanic acid.
Specific examples of the unsaturated fatty acids among the fatty acid-based lubricants include myristoleic acid (tetradecenoic acid), palmitoleic acid (hexadecenoic acid), oleic acid (cis-9-octadecenoic acid), elaidic acid (trans-9-octadecenoic acid), ricinoleic acid (octadecadienoic acid), vaccenic acid (cis-11-octadecenoic acid), linoleic acid (octadecadienoic acid), linolenic acid (9,11,13-octadecatrienoic acid), elestearic acid (9,11,13-octadecatrienoic acid), gadoleic acid (icosanoic acid), erucic acid (docosanoic acid), nervonic acid (tetradocosanoic acid), etc. These may be used in combination of two or more kinds.

Examples of the fatty acid metal salt-based lubricants include the lithium salts, calcium salts, magnesium salts, and aluminum salts of the fatty acids of the fatty acid-based lubricants. Two or more of these may be used in combination.

As the antistatic agent, cationic, anionic, nonionic, amphoteric, fatty acid partial esters such as glycerin fatty acid monoesters, and the like can be used.
Specifically, alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, benzalkonium salts, N,N-bis(2-hydroxyethyl)-N-(3-dodecyloxy-2-hydroxypropyl)methyl ammonium methosulfate, (3-lauryl amidopropyl)trimethyl ammonium methyl sulfate, stearamidopropyl dimethyl-2-hydroxyethyl ammonium nitrate, stearamidopropyl dimethyl-2-hydroxyethyl ammonium phosphate, cationic polymers, alkyl sulfonates, alkyl benzene sulfonates, sodium alkyl diphenyl ether disulfonate, alkyl nitrate ester salts, phosphorus Examples of such esters include alkyl ester salts, alkyl phosphate amine salts, stearic acid monoglyceride, pentaerythritol fatty acid esters, sorbitan monopalmitate, sorbitan monostearate, diglycerol fatty acid esters, alkyldiethanolamines, alkyldiethanolamine fatty acid monoesters, alkyldiethanolamides, polyoxyethylene dodecyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol monolaurates, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyether block copolymers, cetyl betaine, and hydroxyethyl imidazoline sulfate. These may be used in combination of two or more kinds.

Examples of fillers that can be used include talc, calcium carbonate, barium sulfate, carbon fiber, mica, wollastonite, whiskers, etc.

In addition to the above-mentioned additives and processing aids, the flame-retardant styrene-based resin composition in this embodiment may contain optional additives such as antiblocking agents, colorants, antiblooming agents, surface treatment agents, antibacterial agents, and anti-viscosity agents (anti-viscosity agents such as silicone oils described in JP 2009-120717 A, monoamide compounds of higher aliphatic carboxylic acids, and monoester compounds obtained by reacting higher aliphatic carboxylic acids with monohydric to trihydric alcohol compounds).

In this embodiment, the total content of the additives, processing aids, and optional components may be 0.05 to 5 mass% in the flame-retardant styrene-based resin composition.

The flame-retardant styrene-based resin composition of the present embodiment may consist essentially of only the components (A) to (C) and any optional additional components, or may consist of only the components (A) to (C), or only the components (A) to (C) and any optional additional components.
The phrase "consisting essentially of only the components (A) to (C) and any optional additional components" means that 95 to 100 mass % (preferably 98 to 100 mass %) of the flame-retardant styrene-based resin composition is made up of the components (A) to (C) or the components (A) to (C) and any optional additional components.
The flame-retardant styrene-based resin composition of the present embodiment may contain inevitable impurities in addition to the components (A) to (C) and optional additional components, as long as the effects of the present invention are not impaired.

[Physical properties of flame-retardant styrene-based resin composition]
<Flame retardancy>
The flame retardancy of the flame-retardant styrene-based resin composition of this embodiment is preferably within the standard in the UL94 vertical flame test (UL94-V test), that is, the flame retardancy class is preferably V-0 to V-2.
In the present disclosure, flame retardancy can be evaluated by the method described in the Examples section below.

<Melt flow rate (MFR)>
The melt flow rate of the flame-retardant styrene-based resin composition of the present embodiment is preferably 1 g/10 min or more, more preferably 2 g/10 min or more. If it is less than 1 g/10 min, the fluidity is low, and there is a risk that it will be difficult to mold large or thin products.
In this disclosure, the melt flow rate is a value measured in accordance with ISO 1133 under conditions of a temperature of 200° C. and a load of 49 N.

<Charpy impact strength>
The Charpy impact strength of the flame-retardant styrene-based resin composition of the present embodiment is preferably 1.2 kJ/m ² or more, more preferably 6 kJ/m ² or more. If it is less than 1.2 kJ/m ² , there is a concern that it may be damaged during use in applications such as internal parts of office automation products.
In this disclosure, the Charpy impact strength is a value measured in accordance with ISO 179.

<Light resistance>
The light resistance of the flame-retardant styrene-based resin composition of the present embodiment is preferably such that the color difference ΔE is 10 or less, more preferably 5 or less. If the color difference ΔE is greater than 10, the composition may not be usable outdoors due to a decrease in strength, and may also discolor indoors, impairing the design and recyclability.
In this disclosure, the color difference ΔE is a value measured in accordance with JIS K7103 and JIS K7105 using a xenon lamp weather meter, maintaining the temperature of a black panel at 63° C., and measuring the color difference (ΔE) after 300 hours.

[Method for producing flame-retardant styrene-based resin composition]
The flame-retardant styrene-based resin composition of the present embodiment can be produced by melt-kneading each component by any method. For example, a high-speed agitator such as a Henschel mixer, a batch-type kneader such as a Banbury mixer, a single-screw or twin-screw continuous kneader, a roll mixer, or the like can be used alone or in combination. The heating temperature during kneading is usually selected in the range of 180 to 260°C.

[Molded products]
The flame-retardant styrene-based resin composition of the present embodiment can be used to produce a molded article by the above-mentioned melt kneading molding machine, or by using pellets of the obtained flame-retardant styrene-based resin composition as a raw material, through injection molding, injection compression molding, extrusion molding, blow molding, press molding, vacuum molding, foam molding, or the like.
The flame-retardant styrene-based resin composition of the present embodiment can be suitably used for molded articles, particularly injection molded articles (including injection compression), office automation equipment such as copiers, fax machines, televisions, radios, tape recorders, video decks, personal computers, printers, telephones, information terminals, refrigerators, and microwave ovens, home appliances, housings and various parts of electric and electronic devices, foamed insulation materials, insulating films, and the like.

The following provides a more detailed explanation of the present invention based on examples and comparative examples, but the present invention is not limited to these examples.

<Measurement and evaluation methods>
The physical properties of the resin compositions obtained in each of the Examples and Comparative Examples were measured and evaluated according to the following methods.

(1) Content of rubber-like polymer (a1) in rubber-modified styrene-based resin (A) Taking into account the bonding mode of the butadiene segments, the amount of butadiene segments was measured using pyrolysis gas chromatography, and the content of rubber-like polymer (a1) was calculated from the amount of butadiene segments. The unit is mass%.

(2) Average particle size of rubber-like polymer (a1) contained in rubber-modified styrene-based resin (A) An ultra-thin section with a thickness of 75 nm was prepared from the rubber-modified styrene-based resin (A) stained with osmium tetroxide, and a photograph was taken at a magnification of 10,000 times using an electron microscope. In the photograph, the black-stained particles are the rubber-like polymer (a1). From the photograph, the following formula (N1):
Average particle diameter = ΣniDri ³ /ΣniDri ² (N1)
(In the formula, ni is the number of rubber-like polymer (a1) particles having a particle diameter Dri, and the particle diameter Dri is the particle diameter calculated as a circle-equivalent diameter from the area of the particle in the photograph.)
The area average particle size was calculated by the above method, and was taken as the average particle size of the rubber-like polymer (a1). In this measurement, the photograph was scanned at a resolution of 200 dpi, and the measurement was performed using particle analysis software of an image analyzer IP-1000 (manufactured by Asahi Kasei Corporation).

(3) Reduced Viscosity of Rubber-Modified Styrenic Resin (A) The reduced viscosity is an index of the molecular weight of the rubber-modified styrenic resin (A). 1 g of the rubber-modified styrenic resin (A) was added to 20 mL of a mixed solvent of methyl ethyl ketone/methanol (mixed mass ratio 90/10) and dissolved in a shaker for 60 minutes. Next, using a Hitachi himacCR20 centrifuge equipped with an R20A2 rotor, the mixture was centrifuged at 0°C and 20,000 rpm for 60 minutes, and then methanol was added to the supernatant to precipitate the styrenic resin, which is the matrix phase in the rubber-modified styrenic resin (A). The precipitate was filtered and then dried to prepare a sample, and the reduced viscosity (dL/g) was measured in a toluene solution at 30°C and a concentration of 0.5 g/dL.

(4) Contents of styrene monomer unit (b1), methacrylic acid monomer unit, and methyl methacrylate monomer unit in copolymer resin (B) The resin composition was quantified from the integral ratio of the spectrum measured by a proton nuclear magnetic resonance ( ¹ H-NMR) spectrometer.
Sample preparation: 30 mg of resin pellets were dissolved in 0.75 mL of d6-DMSO by heating at 60° C. for 4 to 6 hours.
・Measuring equipment: JNM ECA-500 manufactured by JEOL Ltd.
Measurement conditions: Measurement temperature 25°C, observation nucleus 1H, number of accumulations 64, repetition time 11 seconds.
(Spectral assignment)
Regarding the assignment of the spectrum measured in dimethyl sulfoxide deuterated solvent, the peaks at 0.5 to 1.5 ppm are hydrogen atoms of the α-methyl groups of methacrylic acid, methyl methacrylate, and six-membered cyclic acid anhydrides, the peaks at 1.6 to 2.1 ppm are hydrogen atoms of the methylene groups of the polymer main chain, the peak at 3.5 ppm is hydrogen atoms of the carboxylate ester (-COOCH ₃ ) of methyl methacrylate, and the peak at 12.4 ppm is hydrogen atoms of the carboxylate of methacrylic acid. In addition, the peak at 6.5 to 7.5 ppm is hydrogen atoms of the aromatic ring of styrene. Note that the content of six-membered cyclic acid anhydrides in the resins of the present examples and comparative examples is low, so quantification is generally difficult with this measurement method.

(5) Weight Average Molecular Weight of Copolymer Resin (B) The weight average molecular weight of copolymer resin (B) was measured under the following conditions and by the following procedures.
Sample preparation: The resin was dissolved in tetrahydrofuran at about 0.05% by mass.
Measurement conditions: Instrument: TOSOH HLC-8220GPC (gel permeation chromatography)
Column: super HZM-H
Temperature: 40°C
Carrier: THF 0.35 mL/min
Detector: RI, UV: 254 nm
Calibration curve: Prepared using standard PS manufactured by TOSOH.

(6) Flame Retardancy Using test pieces (b) (size: 127 mm × 12.7 mm, thickness: 1.5 mm or 0.8 mm) prepared by the method described below, flame retardancy was evaluated by a method conforming to the UL94 vertical flame test (UL94-V test) using a 50 W test flame.
The flame of a gas burner was applied to the test piece (b) to evaluate the degree of combustion.
The flame retardancy grade indicates the flame retardancy class as classified by the UL94-V test. The test was performed five times for each test piece and the evaluation was made. The classification method is as follows:
V-0: Total burning time of 5 units is 50 seconds or less, maximum burning time is 10 seconds or less, cotton dripping does not ignite V-1: Total burning time of 5 units is 250 seconds or less, maximum burning time is 30 seconds or less, cotton dripping does not ignite V-2: Total burning time of 5 units is 250 seconds or less, maximum burning time is 30 seconds or less, cotton dripping does ignite Not V: Not UL94 standard

(7) Melt flow rate (MFR)
The melt mass flow rate (g/10 min) of the copolymer resin (B) was measured in accordance with ISO 1133 (200° C., load 49 N).

(8) Charpy Impact Strength The Charpy impact strength (kJ/m ² ) of a test piece (b) prepared by the method described below was measured in accordance with ISO 179 with a notch.

(9) Light resistance: Test piece (a) prepared by the method described below was used to evaluate light resistance in accordance with JIS K7103 and JIS K7105. That is, a xenon lamp weather meter (Ci65, manufactured by Atlas Co., Ltd.) was used to maintain the temperature of the black panel at 63° C., and the color difference (ΔE) between the start of measurement and 300 hours after the start of measurement was evaluated. ΔE was measured under the following conditions using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd.).
(a) Lamp: Halogen lamp; 12V, 50W [manufactured by NARVA]
(b) Wavelength of light: 400 to 700 nm
(c) Light source: C light source 2 degree field of view (d) Measurement hole: Diameter 30mm
(e) Measurement target: reflected light

(10) Surface Appearance The surface appearance was evaluated by observing one surface of a test piece prepared by the method described below. When there were less than 20 dents with an opening of 0.1 mm or more, the surface appearance was evaluated as "OK", and when there were 20 or more dents, the surface appearance was evaluated as "NG".

The materials used in the examples are as follows.
[Component (A)]
・Rubber modified styrene resin (HIPS):
A rubber-modified styrene-based resin, high impact polystyrene (HIPS), was used. The HIPS used polybutadiene as a rubber-like polymer, and the analytical values of the HIPS by the above analytical method were a rubber-like polymer (a1) content of 8.6 mass%, an average particle size of the rubber-like polymer (a1) particles of 1.9 μm, and a reduced viscosity of 0.64 dL/g.

[Component (B)]
[Resin a]
A polymerization raw material composition liquid consisting of 71.3 parts by mass of styrene (ST), 7.3 parts by mass of methacrylic acid (MAA), 6.4 parts by mass of methyl methacrylate (MMA), 15.0 parts by mass of ethylbenzene, and 0.025 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane was continuously supplied at a rate of 1.1 L/hour to a 4-L complete mixing type reactor, then to a polymerization apparatus consisting of a 2-L laminar flow type reactor, and then to a devolatilizer connected to a single-screw extruder for removing volatile matters such as unreacted monomers and polymerization solvent, successively to prepare a resin.
The polymerization reaction conditions in the polymerization step were a polymerization temperature of 122° C. in the complete mixing reactor and a polymerization temperature of 120 to 142° C. in the laminar flow reactor. The devolatilized unreacted gas was condensed in a condenser through which a coolant of −5° C. was passed, and recovered as an unreacted liquid.
The polymer content in the final polymerization solution was measured after drying the polymerization solution at 215° C. under a reduced pressure of 2.5 kPa for 30 minutes according to the formula [(mass of sample after drying/mass of sample before drying)×100%], and was found to be 65.6% by mass, and the weight-average molecular weight was 214,000.
The composition and physical properties of the resulting resin a are shown in Table 1.
[Resins b to d]
Resins b to e were obtained in the same manner as for resin a by adjusting the composition, polymerization temperature conditions, etc. so as to obtain the resin properties shown in Table 1 below.
The composition ratios and physical properties of the resulting resins b to e are shown in Table 1.

[GPPS]
Polystyrene with MFR 2.2 (GPPS, manufactured by PS Japan, G9401) was used.

[Polyphenylene ether]
Polyphenylene ether (Zylon S202A, manufactured by Asahi Kasei Corporation) was used.
The polyphenylene ether resins used were as follows:
Zylon S202A [manufactured by Asahi Kasei Corporation] (Mz molecular weight 6.0 x ¹⁰⁴ )

[Component (C)]
Aluminum diethylphosphinate (hereinafter, DEP) was produced with reference to the method described in JP-A-08-73720.
The DEP lumps were wet-pulverized in water and then classified to obtain DEP having the following average particle sizes.
DEP-1: Aluminum diethylphosphinate, average particle size (d50%) 3.1 μm
DEP-2: Aluminum diethylphosphinate, average particle size (d50%) 20 μm
DEP-3: Aluminum diethylphosphinate, average particle size (d50%) 15 μm
DEP-4: Aluminum diethylphosphinate, average particle size (d50%) 0.8 μm
DEP-5: Calcium diethylphosphinate, average particle size (d50%) 3 μm
The average particle size of the granular phosphinate salts is calculated based on the volume-based particle size measured using a laser diffraction/scattering particle size distribution measuring device. The average particle size is a value measured using a 3% isopropanol aqueous solution as a dispersion medium for the phosphinate salts. Specifically, the average particle size can be determined by performing a blank measurement using a laser diffraction/scattering particle size distribution measuring device LA-910 (manufactured by Horiba, Ltd.) with a dispersion medium of 3% isopropanol aqueous solution, and then inserting a measurement sample so that the measurement sample has a specified transmittance (95% to 70%). The sample was dispersed in the dispersion medium by irradiating it with ultrasonic waves for 1 minute.

[PTFE]
PS-coated PTFE containing 50% polytetrafluoroethylene "SN3300 manufactured by Shine Polymer"

[Additives]
(Phenol-based antioxidant)
3-(3,5-di-tert-butyl-4-hydroxyphenyl)stearyl propionate [manufactured by BASF, Irganox 1076]
(Phosphorus-based antioxidant)
Tris(2,4-di-tert-butylphenyl)phosphite [BASF Corporation, Irgafos 168]

[Examples 1 to 12]
In the composition ratios shown in Tables 2 and 3 below, 0.5 parts by mass of PTFE, 0.2 parts by mass of Irganox 1076, and 0.2 parts by mass of Irgafos 168 were added to 100 parts by mass of each component and components (A) to (C), and then premixed. The resulting premixes were mixed together and melt-extruded at 180°C to 260°C using a twin-screw extruder (Toshiba Machine Co., Ltd., TEM-26SS), to obtain pellets of a flame-retardant styrene-based resin composition as a kneaded product. At this time, the screw rotation speed was 150 rpm, and the discharge rate was 10 kg/hr.
The pellet-shaped flame-retardant styrene-based resin composition thus obtained was molded into a test piece (a) using an injection molding machine manufactured by Japan Steel Works, Ltd. equipped with an ISO standard test piece type A mold at a cylinder temperature of 220° C., a mold temperature of 50° C., an injection pressure (gauge pressure 40-60 MPa), an injection speed (panel set value) of 50%, and an injection time/cooling time of 5 sec/20 sec. The test piece thus obtained was used to measure the Charpy impact strength, Vicat softening temperature, and light resistance, and to evaluate the surface appearance of the molded article. Flame retardancy was evaluated by preparing test pieces (b) using an injection molding machine manufactured by Japan Steel Works, Ltd., equipped with a pin-gate flat mold measuring 127 mm x 12.7 mm x 1.5 mm thick, with a cylinder temperature of 220°C, a mold temperature of 50°C, injection pressure (gauge pressure 40-60 MPa), injection speed (panel set value) of 50%, and injection time/cooling time = 5 sec/20 sec. The results are shown in Table 2.

[Comparative Examples 1 to 6]
In Comparative Examples 1 to 6, pellets of resin compositions were obtained in the same manner as in the Examples, except that the compositions were changed as shown in Table 3. The results of the measurements and evaluations of the various physical properties are shown in Table 3.

As shown in Table 2, Examples 1 to 12 have high flame retardancy (V-0 or V-1 at a thickness of 1.5 mm) and are excellent in impact resistance, heat resistance, light resistance, and molded appearance. In addition, the good dispersion results in a material with high elasticity and rigidity.

As shown in Table 3, in Comparative Examples 1 and 2, without the specific copolymer resin (B), the dispersibility was poor, flame retardancy was not obtained, and the impact strength and molded appearance were poor.
Regarding Comparative Example 3, as shown in Table 3, when polyphenylene ether was used in place of the specific copolymer resin (B), the light resistance, impact strength and molded appearance were deteriorated.
Regarding Comparative Example 4, as shown in Table 3, when the amount of component (B) was large, the fluidity and impact strength decreased.
In Comparative Example 5, as shown in Table 3, when the amount of component (C) is large, the fluidity and impact strength are reduced. On the other hand, when the amount of component (C) is small, as in Comparative Example 6, flame retardancy is not obtained.

Molded articles containing the flame-retardant styrene-based resin composition of the present invention can be suitably used for thin-walled products, sheets, films, etc., such as computer parts for desktop computers and notebook computers, mobile phone parts, electrical and electronic equipment, personal digital assistants, home appliance parts, automobile parts, industrial materials, and building materials.

Claims (5)

40 to 85% by mass of a rubber-modified styrene-based resin (A);
a copolymer resin (B) containing a styrene-based monomer unit (b1), an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit in an amount of 5.0 to 30% by mass;
The following general formula (1):

[In the above formula (1), R ¹¹ and R ¹² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms; M ¹ is at least one selected from the group consisting of calcium ion, magnesium ion, aluminum ion, zinc ion, bismuth ion, manganese ion, sodium ion, potassium ion, and protonated nitrogen base; a represents the ionic valence of M ¹ and is an integer of 1 to 3; m ¹ is an integer of 1 to 3; a=m ^1. When there are a plurality of ^{R 11} and R ¹² , each R ¹¹ and R ¹² may be the same or different.], and a phosphinic acid salt represented by the following formula (2):

[In the formula, R ²¹ and R ²² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms; L ²³ is a linear or branched alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 10 carbon atoms, an alkylarylene group having 7 to 10 carbon atoms, or an arylalkylene group having 7 to 10 carbon atoms; M ² is at least one selected from the group consisting of calcium ion, magnesium ion, aluminum ion, zinc ion, bismuth ion, manganese ion, sodium ion, potassium ion, and protonated nitrogen base; b represents the ionic valence of M ² and is an integer of 1 to 3; m ² is an integer of 1 to 3; i is an integer of 1 or 2; and b×i=2m ^2. When there are a plurality of R ²¹ and R ²² , each R ²¹ and R ²² may be the same or different. and 10 to 30 mass % of a flame retardant (C) containing at least one phosphinate selected from the group consisting of diphosphinates represented by the formula (I)
the copolymer resin (B) is a copolymer resin having a styrene-based monomer unit (b1), an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit, or a copolymer resin composed only of a styrene-based monomer unit (b1) and an unsaturated carboxylic acid-based monomer unit,
the styrene-based monomer unit (b1) is contained in an amount of 69.7 to 97.6 mass%, the unsaturated carboxylic acid-based monomer unit is contained in an amount of 2.4 to 14.1 mass%, and the unsaturated carboxylic acid ester-based monomer unit is contained in an amount of 0 to 16.2 mass%, when the total content of the styrene-based monomer unit (b1), the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit is taken as 100 mass%,
the unsaturated carboxylic acid monomer is methacrylic acid, acrylic acid, fumaric acid or itaconic acid, and the unsaturated carboxylic acid ester monomer is methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate or cyclohexyl (meth)acrylate;
The flame retardant (C) is granular, and the average particle size of the flame retardant (C) is more than 0.5 μm and not more than 10 μm. The flame-retardant styrene-based resin composition according to claim 1, wherein the rubber-modified styrene-based resin (A) comprises a matrix of a styrene-based resin and particles of a rubber-like polymer (a1). The flame-retardant styrene-based resin composition according to claim 1 or 2, having a melt flow rate of 1 gram/10 minutes or more. the total content of the rubber-modified styrene-based resin (A), the copolymer resin (B), the flame retardant (C) and any optional additional components is 95 to 100% by mass based on the entire flame-retardant styrene-based resin composition;
The flame-retardant styrene-based resin composition according to any one of claims 1 to 3, wherein the optional added component is any one of an antioxidant, a weather resistance agent, a lubricant, an antistatic agent, a filler, a flame retardant auxiliary, an antiblocking agent, a colorant, an antiblooming agent, a surface treatment agent, an antibacterial agent, and an anti-dye agent. A molded article comprising the flame-retardant styrene-based resin composition according to any one of claims 1 to 4.