JPH04145151A - Flame-retardant resin composition - Google Patents

Abstract

PURPOSE:To obtain a transparent flame-retardant resin composition suitable for office devices such as OA device, etc., having excellent flame retardance, impact resistance, molding processing properties and good appearance of molded article by copolymerizing styrene bromide in a rubber reinforced thermoplastic resin. CONSTITUTION:A composition which comprises (A) a graft copolymer obtained by polymerizing A2: 90-30 pts.wt. monomer selected from styrene bromide, (meth) acrylic acid alkyl ester, maleic anhydride, etc., in the presence of A1: 10-70 pts.wt. rubber polymer and having <=0.01 difference between refractive index of the component A1 and that of the copolymer of the component A2 is blended with (B) a copolymer obtained by polymerizing styrene bromide with (meth) acrylic acid alkyl ester, etc., and (C) a flame-retardant in the weight ratio of the component A/B/C=15-100/0-85/0-30 and has <=0.01 difference between refractive index of the component A and that of the component B. Further 5-80wt.% of the composition is mixed with (D) 20-95wt.% another thermoplastic resin polymer <=0.01 difference between refractive index of the composition and that of the thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a resin composition that is excellent in impact resistance, appearance of molded articles, self-extinguishing properties, and excellent in transparency.

b. Prior Art Conventionally, thermoplastic resins imparted with impact resistance by rubber-like polymers are well known as resins collectively referred to as ABS resins. Thermoplastic resins imparted with impact resistance may be required to have both flame retardancy and transparency depending on the application.

This is especially true when used in household goods, electrical appliances, appliances and other products, products such as automobiles, and building materials. Transparent resins with good impact resistance include resin compositions obtained by melt-mixing a styrene-methyl methacrylate copolymer and a styrene-butadiene block copolymer having almost the same refractive index, and butadiene polymers. Graft copolymers, in which vinyl monomers such as styrene and methyl methacrylate are grafted onto rubber-like substances such as styrene-butadiene copolymers, are known.

C1 Problems to be Solved by the Invention However, these resin compositions are easily scorched;
Impact resistance is also poor. For this reason, there is an increasing demand for flame retardancy.

Known methods of imparting flame retardancy to these rubber-reinforced thermoplastics, including ABS resins, consist of blending flame retardants, often such flame retardants with brominated diphenyl oxide compounds or Contains brominated polycarbonate compounds.

However, when these flame retardants are added, there are problems such as loss of transparency, poor processability, and poor appearance of the molded product due to welding.

d. Means for Solving the Problems The present invention achieves excellent flame retardancy, impact resistance, moldability, and appearance of molded products by copolymerizing brominated styrene into a rubber-reinforced thermoplastic resin. The present invention aims to provide a flame-retardant resin composition that maintains transparency.

In the present invention, the following components (A), (B) and (C) are combined into (A)/(B)/(C) -15 to 100/0
~85 A flame retardant resin composition containing 10 to 30% by weight, in which when component (B) is used, the difference in refractive index with component (A) is 0.01 or less. The present invention provides a characteristic flame-retardant resin composition (hereinafter referred to as the flame-retardant resin composition according to claim (1)).

(A) In the presence of 10 to 70 parts by weight of component rubbery polymer (a), 5 to 50% by weight of brominated styrene, 10 to 95% by weight of (meth)acrylic acid alkyl ester, and maleic anhydride, aromatic One or more monomers selected from vinyl monomers, maleimide monomers, and vinyl cyan monomers 85-0
Monomer (b) consisting of 90 to 30 parts by weight (a+b
= 100 parts by weight), and the difference between the refractive index of the rubbery polymer (a) and the refractive index of the monomer (b) copolymer is 0.01 or less. Union,
.

(B) Components 5 to 50% by weight of brominated styrene, 5 to 95% by weight of (meth)acrylic acid alkyl ester, and aromatic vinyl monomers, vinyl cyanide monomers, maleic anhydride, and maleimide monomers. One or more selected monomers 90
A copolymer obtained by polymerizing ~0% by weight, (C) a component flame retardant, and a refractive index of 5 to 80% by weight of the flame retardant resin composition according to claim (1). To provide a flame-retardant resin composition (hereinafter referred to as the flame-retardant resin composition according to claim (2)) comprising 20 to 95% by weight of another thermoplastic resin having a difference of o, oi or less. It is something.

In addition, in this specification, the flame-retardant resin composition according to claim (1) and the flame-retardant resin composition according to claim (2) are collectively referred to as the flame-retardant resin composition of the present invention. collectively.

The present invention will be explained in more detail below.

Component (A) of the present invention is a rubbery polymer (a) 10-7
5-50% by weight, preferably 10-38% by weight, particularly preferably 15-50% by weight of brominated styrene, in the presence of 0 parts by weight, preferably 12-66 parts by weight, (meth)acrylic acid alkyl ester 10 ~95% by weight, preferably 15 to 75% by weight, and one or more monomers selected from maleic anhydride, aromatic vinyl monomers, maleimide monomers, vinyl cyan monomers 85 ~0% by weight of monomer (b) 90-30 parts by weight, preferably 88-34 parts by weight
Parts by weight, particularly preferably 85 to 50 parts by weight (a ten b
= 100 parts by weight), and the difference between the refractive index of the rubbery polymer (a) and the refractive index of the copolymer of the monomer mixture (b) is 0.01 or less, preferably 0.00
5 or less.

Examples of the rubbery polymer (a) include polybutadiene, butadiene-styrene copolymer, polyisoprene, butadiene-acrylonitrile copolymer, ethylene-propylene-(dienemethylene) copolymer, isobutylene-isoprene copolymer, acrylic Hydrogenated diene systems such as rubber, styrene-butadiene block copolymer, styrene-butadiene-styrene block copolymer, styrene-butadiene-styrene radial teleblock copolymer, styrene-isoprene-styrene block copolymer rubber, 5EBS, etc. Examples include (block) copolymers, polyurethane rubber, and silicone rubber.

Preferred rubbery polymers (a) include 30 to 98% by weight of conjugated diene monomers such as butadiene and isoprene, 1 to 60% by weight of brominated styrene, and 0 to 60% by weight of aromatic vinyl monomers, preferably Copolymer rubber obtained by copolymerizing 1 to 50% by weight, polybutadiene, butadiene-styrene copolymer, ethylene-propylene-(dienemethylene) copolymer, acrylic rubber, acrylic copolymerized with brominated styrene. Examples include silicone rubber, silicone rubber, and silicone rubber copolymerized with a graft-crossing agent.

The brominated styrenes graft-polymerized in the presence of the rubbery polymer (a) include monobromostyrene, dipromostyrene and tribromostyrene.

Among these, dipromostyrene is most preferred.

Examples of the (meth)acrylic acid alkyl ester include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and among them, methyl methacrylate is preferred.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, O-methylstyrene, m-methylstyrene, P-methylstyrene, chlorstyrene, dichlorostyrene, α-ethylstyrene, and methyl-α-methylstyrene. , dimethylstyrene, etc. Among these, styrene, α-methylstyrene and p-methylstyrene are preferred.

Examples of the maleimide monomers include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(
Examples include p-bromophenylmaleimide, tribromophenylmaleimide, N-(p-chlorophenyl)maleimide, and among these, maleimide, N-phenylmaleimide, N-cyclohexylmaleimide, and tribromophenylmaleimide are preferred.

As the vinyl cyan monomer, acrylonitrile,
Examples include methacrylonitrile, and among these, acrylonitrile is preferred.

(8) The content of the rubbery polymer (a) in the component is 10 to
The amount is 70 parts by weight, preferably 12 to 66 parts by weight, and more preferably 15 to 50 parts by weight. Rubbery polymer (a)
If the content is less than 10 parts by weight, impact resistance will decrease,
If it exceeds 70 parts by weight, the grafting rate, surface gloss and flame retardance of the resin will decrease.

The amount of brominated styrene in the monomer C3) used in component (A) is 5 to 50% by weight, preferably 5 to 40% by weight.
Weight%. When the amount of brominated styrene is less than 5% by weight, a sufficient flame retardant effect cannot be obtained, and when it exceeds 50% by weight, impact resistance decreases.

The amount of (meth)alkyl acrylate in monomer (b) used in component (A) is 10 to 95% by weight.
, preferably 15 to 75% by weight, more preferably 20 to 75% by weight
It is 72% by weight. When the amount of (meth)alkyl acrylic ester is less than 10% by weight, it is difficult to obtain transparency;
In addition, poor appearance occurs due to welding, and if it exceeds 95% by weight, impact resistance decreases.

One or more monomers selected from maleic anhydride, aromatic vinyl monomers, maleimide monomers, and vinyl cyan monomers in monomer (b) used in component (A). The content is 85-0% by weight, preferably 80-5% by weight, more preferably 75-15% by weight.

If the content of these monomers exceeds 85% by weight, impact resistance will be poor.

Intrinsic viscosity of the matrix resin component of component (A) [η] (
(measured in methyl ethyl ketone at 30°C; the same applies hereinafter) is preferably 0.1 to 1.5 di/g, more preferably 0.3 to 1. It is Odi/g. If [η] is less than 0.1 d1/g, impact strength will not be sufficiently developed, and if [η] exceeds 1.5 a/g, moldability will decrease. Here, the matrix resin is (A)
It refers to a resin component other than the grafted rubber component in the component, and the above-mentioned intrinsic viscosity [η] is a value determined by measuring the methyl ethyl ketone dissolved content of component (A) according to a conventional method.

The grafting ratio of component (A) is preferably 10 to 200%, more preferably 20 to 120%.

If the grafting ratio is low, the impact resistance will be reduced, and if the grafting ratio is high, dripping (molten dripping) during combustion will likely occur.

Component (B) of the present invention is 5 to 50% by weight of brominated styrene.
, 5 to 95% by weight of (meth)acrylic acid alkyl ester, and 90 to 90% of one or more monomers selected from aromatic vinyl monomers, vinyl cyanide monomers, maleic anhydride, and maleimide monomers. A copolymer obtained by polymerizing 0% by weight, and the difference in refractive index from component (8) is 0.01
The graft copolymer is as follows.

Each component in the above component (B), namely brominated styrene,
As the (meth)acrylic acid alkyl ester, aromatic vinyl monomer, vinyl cyanide monomer, maleic anhydride, and maleimide monomer, the same ones as those used in the component (A) are used. be able to.

Among the above components (B), preferred are copolymers obtained by polymerizing dipromostyrene, methyl methacrylate, acrylonitrile, and styrene.

The amount of brominated styrene in component (B) is 5 to 50% by weight
, preferably 10 to 45% by weight. When the amount of brominated styrene is less than 5% by weight, the flame retardant effect decreases,
If it exceeds % by weight, the impact resistance will decrease.

The amount of (meth)acrylic acid alkyl ester is 5 to 95% by weight, preferably 20 to 90% by weight. If it is less than 5% by weight, the appearance due to welding will be poor, and if it exceeds 95% by weight, impact resistance will be poor.

The content of one or more monomers selected from aromatic vinyl monomers, vinyl cyanide monomers, maleic anhydride, and maleimide monomers is 90 to 0% by weight.

If the content of these monomers exceeds 90% by weight, impact resistance will be poor. The polymerization method for component (B) is not particularly limited, but a preferred polymerization method is to
After starting the emulsion polymerization reaction using 40% by weight, the remaining monomers (100 to 60% by weight) were added continuously in equal amounts at a rate lower than the polymer formation rate until the polymerization conversion rate was increased. A method of polymerizing until it reaches 80% or more is exemplified.

The bromine-containing copolymer (B) synthesized by this method is
Brominated styrene is more uniformly incorporated into the copolymer than in component (B) synthesized by other polymerization methods, and the copolymer has an excellent flame retardant effect.

The refractive index difference between component (B) and component (A) is 0.01 or less,
Preferably it is 0.005 or less. If it exceeds 0.01, transparency will be poor.

The intrinsic viscosity [η] of component (B) is preferably 0.1 to 1
．． 5 a/g, more preferably 0.3 to 1.0
dl/g. If (η) is less than 0.1Li1/g, impact strength will not be sufficiently developed, and if it exceeds 1.5 a/g, moldability will decrease.

Component (C) of the present invention is a flame retardant, and includes, for example, a phosphorus-containing compound. Preferred are phosphate compounds, specifically triphenyl phosphate,
Examples include tricresyl phosphate.

To impart a flame retardant effect, it is also possible to use antimony oxide, which has a high synergistic effect when used with a halogen compound. In addition, when obtaining a transparent flame-retardant resin, it is preferable to use the resin within a range that does not impair transparency. The amount of antimony oxide contained in the composition of the present invention is usually 20
% by weight or less, preferably from 0.05 to 10% by weight, more preferably from 0.1 to 5% by weight, particularly preferably from 0.2 to 5% by weight
It is 3% by weight.

In the flame-retardant resin composition according to claim (1), (8)
The blending ratio of the components is 15 to 100% by weight, preferably 25% by weight.
~100% by weight, more preferably 30-98% by weight,
Particularly preferred is 35 to 95% by weight. If the amount of component (A) is less than 15% by weight, sufficient impact resistance cannot be obtained.

The blending ratio of component (B) is 0 to 85% by weight, preferably 0.
~75% by weight, more preferably 2-75% by weight, particularly preferably 5-65% by weight. If the content of component (B) exceeds 85% by weight, impact resistance will decrease. When component (B) is blended in this proportion, moldability and surface appearance of the molded product are excellent.

The blending ratio of component (C) is 0 to 30% by weight, preferably 2
-25% by weight, more preferably 5-20% by weight. If the blending ratio of component (C) exceeds 30% by weight, thermal stability will be poor.

In the flame-retardant resin composition according to claim (1), the content of the rubbery polymer is preferably 5 to 65% by weight,
More preferably, it is 10 to 40% by weight. If the content of the rubbery polymer is less than 5% by weight, the impact resistance will be low;
If it exceeds % by weight, flame retardancy will decrease.

The bromine content in the flame retardant resin composition according to claim (1) is preferably 1 to 30% by weight, more preferably 5% by weight.
~20% by weight. If the bromine content is less than 1%, a sufficient flame retardant effect will not be obtained, and if it exceeds 30% by weight, the impact strength will decrease.

The flame-retardant resin composition according to claim (1) is characterized in that brominated styrene is copolymerized in the graft copolymer of component (A). In this composition, since the brominated styrene that imparts flame retardancy is uniformly dispersed in the resin composition, the flame retardance is not only improved, but also the graft copolymer of component (A) and (B) Compatibility with components is improved and impact resistance is also improved. Furthermore, since brominated styrene is copolymerized around the rubber particles (grafted part), it has an excellent effect of preventing dripping during combustion.

In the flame-retardant resin composition according to claim (1), since the (A) component and the (B) component are copolymerized with an alkyl (meth)acrylate ester, there is no problem with appearance defects due to welding during molding and molding. Processability is significantly improved.

Examples of polymerization methods for component (A) and component (B) include bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, and precipitation polymerization, and a combination of these methods may also be used. Moreover, a continuous method, a semi-continuous method, or a batch method can also be applied. In order to copolymerize brominated styrene more uniformly in the polymer, increase the dispersibility of brominated styrene in the resin composition, and improve the flame retardant effect, (batch) incremental polymerization is used in the emulsion polymerization method. Preferably legal.

The flame retardant resin composition according to claim (2) is the flame retardant resin composition according to claim (1).
5 to 80% by weight of the flame retardant resin composition described above and 20 to 20 other thermoplastic resins having a refractive index difference of 0.01 or less
It is a flame retardant resin composition consisting of 95% by weight.

That is, the flame retardant resin composition according to claim (1) has a refractive index difference of 0.01 or less, preferably 0.00.
5 or less, such as ABS resin, A
BS resin, ABS resin, polycarbonate, pps,
ppo, POM, polyamide, PBT, PET,
According to claim (2), by blending one or more thermoplastic resins selected from polyvinyl chloride, polyolefin, polyacetal, epoxy resin, silicone resin, polyurethane, vinylidene fluoride, HIPS, polystyrene, and thermoplastic elastomer. A flame retardant resin composition can be obtained. The blending amount is 20-95% by weight, preferably 20-80% by weight of the thermoplastic resin based on 5-80% by weight, preferably 20-80% by weight of the flame-retardant resin composition according to claim (1). %. If the flame-retardant resin composition according to claim (1) is less than 5% by weight, the excellent properties of the flame-retardant resin of the present invention cannot be sufficiently obtained, and if it is more than 95% by weight, other thermoplastics This is not preferable because the excellent properties of the resin cannot be obtained.

As other thermoplastic resins, in particular polycarbonate, p
ps, ppo, polyamide, PBT, PET,
By using polyvinyl chloride, polyacetal, epoxy resin, silicone resin, or polyurethane, a composition with excellent flame retardancy and transparency can be obtained.

Furthermore, the flame-retardant resin composition of the present invention may optionally contain stabilizers such as antioxidants and ultraviolet absorbers, lubricants such as silicone oil and low molecular weight polyethylene, calcium carbonate, talc, clay, and titanium oxide. , silica, magnesium carbonate, carbon black, barium sulfate, calcium oxide, aluminum oxide, mica, glass beads, glass fiber, fillers such as metal fillers, halogen-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, silicon-containing compounds, metals Flame retardants such as (water) oxides, dispersants, blowing agents, colorants, etc. can be added.

As a device for melt-mixing each component used in manufacturing the flame-retardant resin composition of the present invention, known devices such as an open type mixing roll, a closed type Banbury mixer, 1 extruder, 1 kneader, and 1 continuous mixer are used. can do.

The flame-retardant resin composition of the present invention is molded into molded products by extrusion molding, injection molding, compression molding, etc., and these molded products have excellent flame retardancy, impact resistance, and practical moldability. Since it has a good surface appearance, it is extremely useful as household goods, electrical equipment, office equipment, and other products, automobiles, and construction materials.

e. Examples The present invention will be specifically explained by examples below.
The present invention is not limited to these examples.

In addition, in the following examples, parts mean parts by weight.

Examples 1 to 8 and Comparative Examples 1 to 8 [a] 0.2 parts of potassium stearate and lauric were placed in a stainless steel polymerization reactor with an internal volume of 100 mm and equipped with 4-stage paddle blades for stirring the rubber. 90 parts of ion exchange water containing 1.5 parts of potassium acid, 0.1 part of sodium alkylnaphthalene sulfonate, 0.1 part of potassium hydroxide and 1.5 parts of potassium chloride were charged, and 100 parts of butadiene was added thereto. The temperature was raised under stirring at a rotational speed of 90 rpv in a nitrogen atmosphere, and when it reached 45°C, potassium persulfate was added, and the reaction temperature was then increased to 45°C.
The polymerization reaction was carried out while controlling the temperature to be kept constant at °C. When the polymerization rate reached 90%, 0.1 part of diethylhydroxyamine was added to stop the reaction, and unreacted monomer was virtually removed by ruthless steam. By removing the rubber-like polymer latex of Example 1 shown in Table 1(a) (
Polybutadiene rubber latex) was obtained.

1. In a separable flask equipped with a reflux condenser, a thermometer, and a stirrer, add 15 parts of the polybutadiene rubber latex obtained by the above manufacturing method in terms of solid content, and 65 parts of ion-exchanged water.
0.35 parts of rosin acid soap, 4 parts of dipromostyrene.
4 parts and 21.1 parts of methyl methacrylate, then 0.2 parts of sodium birophosphate and 0.0 parts of ferrous sulfate heptahydrate.
．． Part 01, and Grape IJ! A solution of 0.4 parts dissolved in 20 parts of ion-exchanged water was added. Then, 0.07 parts of cumene hydroperoxide was added to start polymerization, and after polymerization for 1 hour, 45 parts of ion-exchanged water, 0.7 parts of rosin acid soap, 10.3 parts of dipromostyrene, and methyl methacrylate were added. 49.2 parts and 0.01 part of cumene hydroperoxide were added continuously over a period of 2 hours, and polymerization was continued for an additional hour to complete the reaction. The obtained copolymer latex was coagulated by adding sulfuric acid, washed with water, and dried to obtain component (8) of Example 1.

Component (A) of Examples 2 to 8 and Comparative Examples 1 to 8 was obtained in the same manner using the rubber component monomer mixtures shown in Table 1(a) and Table 2(a). .

■ and two-year production In a separable flask equipped with a reflux condenser, a temperature needle, and a stirrer, 250 parts of ion-exchanged water and 3 parts of potassium rosinate.
parts, dipromostyrene 8.6 parts, methyl methacrylate 1 part
7.1 parts of acrylonitrile, 4.3 parts of acrylonitrile and 0.03 parts of t-dodecyl mercaptan, then 0.05 parts of sodium ethylenediaminetetraacetate, 0.0 parts of ferrous sulfate heptahydrate.
A solution of 0.002 parts of sodium formaldehyde sulfoxylate and 0.1 part of sodium formaldehyde sulfoxylate dissolved in 8 parts of ion-exchanged water was added. Then, 0.025 parts of diisopropylbenzene hydroperoxide was added to start polymerization, and after polymerization for 1 hour, 20.0 parts of dipromostyrene, 400 parts of methyl methacrylate, and 10.0 parts of acrylonitrile were added.
1 part, 0.09 parts of L-dodecylmercaptan, and 0.09 parts of sodium ethylenediaminetetraacetate in 8 parts of ion-exchanged water.
．． A solution containing 0.05 parts of ferrous sulfate 7, 0.002 parts of ferrous sulfate 7-eternal and 0.1 part of sodium formaldehyde sulfoxylate was added continuously over 1.5 hours, and the reaction was further polymerized for 1 hour. completed. The obtained copolymer latex was coagulated by adding sulfuric acid, washed with water, and dried to obtain component (B) of Example 2.

(B) of Example 3.5.7.8 and Comparative Example 4.6.8 was prepared in the same manner using the monomer mixtures shown in Table 1(B) and Table 2(B). Got the ingredients.

Using the (A) component, (B) component and (C) component shown in Notice Table-1 and Table-2, blend them in the proportions shown in Table-1,
The mixture was mixed using a Henschel type mixer and then melt-kneaded using a vented extruder at 220°C to obtain a pelletized transparent flame-retardant resin composition. The test piece was produced using an injection molding machine with the cylinder temperature set at 230°C. Table 1 shows the evaluation results of the obtained transparent flame-retardant resin composition.
and shown in Table-2.

In addition, each physical property of the obtained composition was evaluated by the following method.

(1) Izot impact strength ASTM D256 1/4', 23°C with two notches (kg cm/cm) (2) Combustion test compliant with UL-94. Test piece: 1/16″×172″×
5" (3) Measurement of clouding Measured with a haze meter (MSC connection type).

Test piece: 1/8'X2''x3# Table 8 Visual evaluation As is clear from the results shown in Tables 1 and 2, the compositions of Examples 1 to 8 had excellent flame retardancy. Moreover, it has excellent transparency.

On the other hand, the compositions of Comparative Examples 1 and 2 are compositions in which the amount of rubbery polymer used in component (A) is outside the range of the present invention. Comparative Example 2, which uses a large amount, has poor flame retardancy.

In addition, the compositions of Comparative Examples 3 and 4 are compositions in which the amount of bromostyrene used in component b in the graft copolymer (A) or in the copolymer (B) is outside the range of the present invention. ,
Comparative Example 3, in which a small amount was used, had poor flame retardancy, and Comparative Example 4, in which a large amount was used, had poor impact resistance and poor appearance due to welding.

Comparative Example 5 is an example in which no (meth)acrylic acid alkyl ester is used, and the flame retardance is good, but the appearance is very poor due to welding.

In Comparative Examples 6 to 8, the difference in refractive index of each component is outside the range of the present invention, and the transparency is poor.

10 Effects of the Invention The flame-retardant resin composition of the present invention has excellent transparency and flame retardancy, and also has high impact resistance and molded appearance at a practical level. have. Moreover,
Good workability during molding.

Therefore, it is possible to mold large molded products and complex molded products such as office equipment such as OA equipment and electrical equipment, and it is a material that is valuable in practical terms, has extremely high industrial value, and is extremely useful in industry. be.

Patent applicant: Japan Synthetic Rubber Co., Ltd.

Claims (2)

[Claims] (1) The following (A) component, (B) component and (C) component are (A)/(B)/(C)=15-100/0-85/
A flame-retardant resin composition containing 0 to 30% by weight, characterized in that when component (B) is used, the difference in refractive index from component (A) is 0.01 or less. A flame-retardant resin composition. (A) In the presence of 10 to 70 parts by weight of component rubbery polymer (a), 5 to 50% by weight of brominated styrene, 10 to 95% by weight of an alkyl (meth)acrylate, and maleic anhydride, aromatic One or more monomers selected from vinyl monomers, maleimide monomers, and vinyl cyan monomers 85-0
Monomer (b) consisting of 90 to 30 parts by weight (a+b
= 100 parts by weight), and the difference between the refractive index of the rubbery polymer (a) and the refractive index of the monomer (b) copolymer is 0.01 or less. (B) Component 5 to 50% by weight of brominated styrene, 5 to 95% by weight of alkyl (meth)acrylate, and aromatic vinyl monomer, vinyl cyanide monomer, maleic anhydride, and maleimide monomer. One or more monomers selected from the body 90~
Copolymer obtained by polymerizing 0% by weight, component (C) flame retardant (2) Consists of 5-80% by weight of the flame-retardant resin composition according to claim (1) and 20-95% by weight of another thermoplastic resin having a refractive index difference of 0.01 or less. A flame-retardant resin composition characterized by: