JP6831327B2 - Flame retardant masterbatch and its manufacturing method - Google Patents

Description

The present invention relates to a flame retardant masterbatch used to impart flame retardancy to a styrene resin and a method for producing the same.

Styrene-based resins are used in a wide range of applications by taking advantage of their characteristics. Among them, flame-retardant resins with high flame retardancy are used in various fields such as word processors, personal computers, printers, OA equipment such as copiers, home appliances such as TVs, VTRs, and audios. ..

Conventionally, various flame retardants have been proposed in order to impart flame retardancy to styrene-based resins. Among them, halogen-containing organic compounds, which are inexpensive and have an excellent balance of physical properties, are often used as flame retardants.

In recent years, as a method of making a styrene resin flame-retardant from the viewpoint of economy and work environment, a masterbatch is prepared by melting and mixing a high-concentration flame retardant and a flame retardant aid with a styrene resin in advance using an extruder. There is an increasing number of methods for producing a styrene-based flame-retardant resin composition having desired physical properties and flame-retardant properties by using the obtained masterbatch and a styrene-based resin. Patent Document 1 is mentioned as a masterbatch technique.

Further, in recent years, in fields such as OA equipment and home appliances, a hot runner molding method using a large molding machine, a gas assist injection method, and the like have been applied in order to cope with the increase in size of plastic parts. Therefore, the resin used is required to have excellent moldability in addition to flame retardancy. Further, in molding deep molded products and the like, reduction of scratches generated at the time of mold release is also regarded as important in order to increase the added value of the product.

Japanese Unexamined Patent Publication No. 2014-205802

Bromine-based flame retardants are often used as flame retardants, but some brominated flame retardants have a high melting point and do not melt at the processing temperature when melt-mixing with an extruder, depending on the kneading conditions. Causes secondary aggregation of flame retardant particles. When the styrene-based flame-retardant resin composition obtained by using the flame retardant masterbatch is molded, molding defects such as a flash occur. Further, when the styrene-based flame-retardant resin composition obtained by using the flame retardant masterbatch whose kneading is too strong is molded, scratches occur at the time of molding release.

The present invention has been made in view of such circumstances, and provides a flame retardant masterbatch having excellent extrudability and uniformity, and a method for producing the same.

The present invention is as follows.
1. 1. A flame retardant masterbatch containing a styrene resin and a flame retardant.
The flame retardant is a flame retardant masterbatch having a melting point of 270 ° C. or higher.
2. 2. The flame retardant masterbatch according to 1 above, wherein the flame retardant is 15 to 90 parts by mass with respect to 100 parts by mass of the styrene resin.
3. 3. The flame retardant masterbatch according to 1 or 2 above, wherein the flame retardant is a brominated diphenylalkane represented by the formula (1).
[In the formula, R is an alkylene group of C _n H _2n (n is an integer of 1 to 10), X ₁ and X ₂ are bromine atoms of an integer 1 to 5, respectively, and X ₁ + X ₂ ≧ 2. ]
4. The flame retardant masterbatch according to 3 above, wherein the brominated diphenylalkane is decabromodiphenylethane.
5. The flame retardant masterbatch according to any one of 1 to 4 above, further comprising a flame retardant aid and talc.
6. 5. The flame retardant masterbatch according to 5, wherein the flame retardant aid is 0 to 15 parts by mass and the talc is 0 to 40 parts by mass with respect to 100 parts by mass of the styrene resin.
7. 5. The flame retardant masterbatch according to 5 or 6 above, wherein the flame retardant aid is antimony trioxide.
8. A method for manufacturing a flame retardant masterbatch using a twin-screw extruder.
The twin-screw extruder includes a plurality of raw material supply units for supplying the raw materials of the flame retardant masterbatch into a cylinder, a kneading unit provided on the downstream side of the raw material supply unit and kneading the raw materials, and the above. A progressive screw provided between the upstream side of the kneading portion and the kneading portion, a vacuum vent port provided on the downstream side of the kneading portion, and a kneading portion provided on the downstream side of the vacuum vent port. Equipped with an outlet for discharging the raw material kneaded in
A step of kneading the raw material supplied from the raw material supply unit in the kneading unit and discharging the raw material from the discharge port is provided.
The raw material contains a styrene resin and a flame retardant, and contains
The melting point of the flame retardant is higher than the maximum temperature between the kneading portion and the outlet.
The flame retardant is supplied into the cylinder from a source other than the most upstream raw material supply section among the plurality of raw material supply sections.
The L / D of the progressive screw on the upstream side of the kneading portion is 1.2 or less.
A method for producing a flame retardant masterbatch, wherein the L / D of the progressive screw between the kneading portions is 0.5 or more.
However, D is the screw diameter (mm), and L is the screw lead length (mm).
9. The method for producing a flame retardant masterbatch according to the above 8, wherein the flame retardant is 15 to 90 parts by mass with respect to 100 parts by mass of the styrene resin.
10. The method for producing a flame retardant masterbatch according to 8 or 9 above, wherein the flame retardant is a brominated diphenylalkane represented by the formula (1).
[In the formula, R is an alkylene group of C _n H _2n (n is an integer of 1 to 10), X ₁ and X ₂ are bromine atoms of an integer 1 to 5, respectively, and X ₁ + X ₂ ≧ 2. ]
11. The method for producing a flame retardant masterbatch according to the above 10, wherein the brominated diphenylalkane is decabromodiphenylethane.
12. The method for producing a flame retardant masterbatch according to any one of 8 to 11 above, wherein the raw material further contains a flame retardant aid and talc.
13. The method for producing a flame retardant masterbatch according to the above 12, wherein the flame retardant aid is 0 to 15 parts by mass and the talc is 0 to 40 parts by mass with respect to 100 parts by mass of the styrene resin.
14. The method for producing a flame retardant masterbatch according to 12 or 13 above, wherein the flame retardant aid is antimony trioxide.
15. A flame retardant masterbatch in which raw materials containing a styrene resin and a flame retardant are kneaded.
The flame retardant is a flame retardant masterbatch having a melting point higher than the maximum temperature reached by the raw materials during kneading.
16. The flame retardant masterbatch obtained by the method according to any one of 8 to 14 or the flame retardant masterbatch according to any one of 1 to 7 or 15 and a styrene resin composition. A method for producing a styrene-based flame retardant resin composition, which comprises a step of melting and mixing the above with an extruder.
17. A molded product made of a styrene-based flame-retardant resin composition obtained by the method according to 16.

According to the present invention, a flame retardant masterbatch having excellent extrudability and uniformity can be produced by extruding under specific manufacturing conditions using a twin-screw extruder, and the flame retardant masterbatch is used. However, the styrene-based flame retardant resin composition can be easily produced by diluting with the styrene-based resin. The obtained styrene-based flame-retardant resin composition can easily obtain a molded product having excellent flame retardancy, appearance of the molded product, and scratch resistance at the time of molding release.

It is a schematic diagram which shows the manufacturing process of this invention.

FIG. 1 is a schematic view of a twin-screw extruder used in the manufacturing method of the present invention. Hereinafter, a method for manufacturing a flame retardant masterbatch using this twin-screw extruder will be described.

FIG. 1 shows the resin composition located from the first raw material supply section 2 located on the upstream side of the twin-screw extruder 1 to the discharge port (die) 5 from the upstream side to the first kneading section 6, A second raw material supply section 3, a second kneading section 7, a vacuum vent 4, a progressive screw 8 on the adjacent upstream side of the second kneading section, and a progressive screw 9 between the kneading sections are provided. Further, a thermometer 10 was provided on the downstream side of the second kneading portion and at the resin composition discharge port for observing the resin temperature. Even if there is no thermometer, it does not affect the actual production.

The raw materials of the flame retardant masterbatch include (A) a styrene resin and (B) a flame retardant. (B) The flame retardant is charged into the cylinder from the second raw material supply unit 3. Further, when the raw material supply section is located downstream from the second raw material supply section, (B) the flame retardant can be added in portions, and the progressive screws 8 and 9 are used in the same manner. The rest of the raw material is charged into the cylinder from the first raw material supply unit. It is desirable to install a side feeder in the raw material supply section after the second raw material supply section and (B) charge the flame retardant.

The forward feed screw 8 is preferably L / D 1.2 or less, and when the L / D of the forward feed screw 8 exceeds 1.2, the resin temperature of the second kneading portion tends to be low, and (B) dispersion of the flame retardant. Tends to get worse. However, D represents the screw diameter (mm), and L represents the screw lead length.

The specific configurations of the first kneading portion 6 and the second kneading portion 7 are not particularly limited, and those having a general configuration can be used, for example, kneading discs (1), (2), (1). ), (1), (2), (3), and the like, and one or more units are arranged.
The kneading discs (1) to (3) have phase angles of 45 degrees, 90 degrees, and 135 degrees, respectively, and have an L / D of 0.25 to 0.8. However, the phase angle represents the twist angle (degrees) between two adjacent blades, L represents the length of the kneading disc (mm), and D represents the screw diameter (mm).

It is desirable that the progressive screw 9 between the second kneading portions has an L / D of 0.5 or more, and if the L / D of the progressive screw 9 is less than 0.5, the resin temperature of the second kneading portion tends to be high. Using a flame retardant masterbatch prepared with a / D of less than 0.5, scratches tend to occur in a molded product of a styrene-based flame-retardant resin composition diluted with a styrene-based resin. However, D represents the screw diameter (mm), and L represents the screw lead length (mm).

As the (A) styrene-based resin used in the flame retardant masterbatch of the present invention, it is desirable to use a rubber-modified styrene-based resin. The rubber-modified styrene resin is obtained, for example, by dissolving a rubber-like polymer in a mixed solution of an aromatic vinyl monomer and an inert solvent, and stirring the mixture to carry out bulk polymerization, suspension polymerization, solution polymerization, or the like. , A polymer obtained by dispersing a rubber-like polymer in the form of particles in a matrix of aromatic vinyl polymers. The molecular weight of the matrix portion is not particularly limited, but the reduced viscosity (η _sp / C) is 0.50 dl / g or more, preferably 0.55 to 0.85 dl / g. If the reduced viscosity exceeds 0.85 dl / g, the fluidity of the composition is too low to hinder molding, and if it is less than 0.55 dl / g, practically sufficient strength cannot be exhibited. is there. The rubber content is not particularly limited, but 4 to 15% by mass, which is generally used for rubber-modified styrene resins, is preferable. It is desirable to determine the rubber content in consideration of the balance between impact strength and rigidity required for the molded product.

Examples of the above aromatic vinyl monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene and the like, and a combination system thereof. Most suitable.

The volume average particle size of the rubber-like polymer contained in the rubber-modified styrene resin is not particularly limited, but is generally 0.4 to 6.0 μm, preferably 0.5 to 3.0 μm. .. If the rubber particle size is too small, the impact resistance is sharply lowered, and conversely, if the particle size is too large, the appearance such as the surface gloss of the molded product tends to be deteriorated.

Further, the rubber-like polymer contained in the rubber-modified styrene resin includes polybutadiene, polyisoprene, a styrene-butadiene copolymer, and the like, and the polybutadiene includes high cis polybutadiene and cis bond having a high content of cis bond. Examples thereof include rubber polybutadiene having a low content. High cis polybutadiene is desirable.

The (B) flame retardant used in the flame retardant masterbatch of the present invention will be described. In the present invention, as the flame retardant (B), one having a melting point higher than the maximum temperature between the second kneading portion 7 and the discharge port 5 is used. Such a flame retardant has poor dispersibility and tends to cause secondary aggregation. However, by producing a flame retardant masterbatch by the method of the present invention, a flame retardant masterbatch having excellent extrudability and uniformity can be obtained. .. The flame retardant type is not particularly limited, and examples thereof include brominated diphenylalkane and brominated phthalimide having a high melting point. A brominated diphenylalkane is desirable and has a structure represented by the following general formula.

In the formula, R is an alkylene group of C _n H _2n (n is an integer of 1 to 10), X ₁ and X ₂ are bromine atoms having an integer of 1 to 5, respectively, and X ₁ + X ₂ ≧ 2.

Specifically, dibromo-substituted products such as diphenylmethane, 1,2-diphenylethane, 1,3-diphenylpropane, and 1,6-diphenylhexane, tribromo-substituted products, tetrabromo-substituted products, pentabromo-substituted products, hexabromo-substituted products, and heptabromo. Substituters, octabromo substitutions, nonabromo substitutions, decabromo substitutions can be mentioned. Preferred are octabromo, nonabromo and decabromo substituteds of diphenylalkanes, with decabromodiphenylethane being particularly desirable. The melting point of the flame retardant (B) is preferably 270 ° C. or higher, more preferably 300 ° C. or higher, further preferably 330 ° C. or higher, still more preferably 345 ° C. or higher.

The amount to be added is not particularly limited, but it is desirable that the amount of (B) flame retardant is 15 to 90 parts by mass with respect to 100 parts by mass of (A) styrene resin. Further, the raw material of the flame retardant masterbatch may include (C) a flame retardant aid and (D) talc. Preferably, (A) 100 parts by mass of the styrene resin, (B) 15 to 90 parts by mass of the flame retardant, 0 to 15 parts by mass of the flame retardant aid, and (D) 0 to 40 parts by mass of talc. It can be partially added.

The (C) flame retardant aid has a function of further enhancing the flame retardant effect of the (B) flame retardant. For example, antimony trioxide, antimony tetroxide, antimony tetroxide, sodium antimonate, etc. Zinc-based compounds such as zinc borate, barium metaborate, anhydrous zinc borate, anhydrous boric acid, etc., tin-based compounds such as zinc stannate and hydroxytinate, and molybdenum-based compounds such as molybdenum oxide and ammonium molybdate. Examples thereof include zirconium oxide and zirconium hydroxide, and zinc sulfide and the like as zinc-based compounds, and antimony trioxide is particularly preferable. The volume particle diameter is preferably 2.0 μm or less, more preferably 1.5 μm or less.

The talc (D) is not particularly limited, but preferably has a volume average particle diameter of 2 to 15 μm, and more preferably 5 to 10 μm.

Further, in order to obtain the flame retardant masterbatch of the present invention, it is possible to further add a colorant, a plasticizer, a lubricant, a heat stabilizer, an ultraviolet absorber, a filler, a reinforcing agent, etc. as additives according to the purpose. You can.

For example, since many black molded products are used, carbon black can be added as a pigment to the flame retardant masterbatch of the present invention as needed to produce a flame retardant masterbatch.
In addition, it is easier to manufacture the flame retardant masterbatch, and it is easier to manufacture the styrene-based flame-retardant resin composition using the flame retardant masterbatch, and the strength is increased. From the viewpoint of fluidity and scratch resistance of the molded product of the flame resin composition, polyolefin wax, higher fatty acid amide, higher carboxylic acid metal salt and the like can be used as the lubricant.

Using the flame retardant masterbatch of the present invention, a styrene-based flame-retardant resin composition can be obtained by diluting with an arbitrary styrene-based resin. The dilution amount of the styrene resin can be arbitrarily determined depending on the amount of the flame retardant in the flame retardant masterbatch and the required flame retardancy of the styrene flame retardant resin composition. 5 to 80 parts by mass of the flame retardant masterbatch 95 to 20 parts by mass of the styrene resin, more preferably 10 to 70 parts by mass of the flame retardant masterbatch 90 to 30 parts by mass of the styrene resin, still more preferably 14 to 30 parts by mass of the flame retardant masterbatch. 63 parts by mass The styrene resin is 86 to 37 parts by mass. Further, the melt-kneading method is not particularly limited, and for example, a method such as a Banbury mixer, a kneader, a single-screw extruder, or a twin-screw extruder can be adopted, and in particular, a single-screw extruder or two. It is preferable to use a shaft extruder. The screw of the single-screw extruder can be full flight, dalmage, pin or madock, but it is particularly preferable to use dalmage.

The molded product of the styrene-based flame-retardant resin composition is preferably applied to OA equipment such as word processors, personal computers, printers and copiers, and home appliances such as TVs, VTRs and audios. The molding method is not particularly limited, but injection molding is preferable, and a hot runner molding method using a large molding machine and a gas assist injection method are also preferably applied.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[(A) Styrene-based resin]
The (A-1) styrene-based resin used had a reduced viscosity of 0.70 dl / g, a gel content of 26.4% by mass, and a rubber-like polymer of 9.4% by mass, and the volume of the rubber-like polymer. It is a rubber-modified styrene resin (HI) of high cis polybutadiene rubber having an average particle size of 2.8 μm and all containing cis-1,4 bonds in a ratio of 90 mol% or more.
The (A-2) styrene resin is a styrene polymer (GP) having a reduced viscosity of 0.74 dl / g and a liquid paraffin content of 2.2% by mass in the styrene resin.
The reduced viscosity, gel content, rubbery polymer content and volume average particle size referred to here were measured by the following methods.

<Reduced viscosity>
A mixed solvent of 15 ml of methyl ethyl ketone (MEK) and 15 ml of acetone is added to 1 g of a styrene resin, dissolved by shaking at 25 ° C. for 2 hours, the insoluble matter is precipitated by centrifugation, the supernatant is taken out by decantation, and 500 ml of methanol is used. Is added to precipitate the resin component, and the insoluble component is filtered and dried. The resin component obtained by the same operation is dissolved in toluene to prepare a sample solution having a polymer concentration of 0.4% (weight / volume). This sample solution and pure toluene were kept at a constant temperature of 30 ° C., and the number of seconds of solution flowing down was measured with an Ubbelohde viscometer, and calculated by the following formula.

η _sp / C = (t1 / t0-1) / C
t0: Number of seconds of pure toluene flowing down t1: Number of seconds of sample solution flowing down C: Polymer concentration

<Gel content>
Styrene-based resin is added to toluene at a ratio of 2.5% by mass, dissolved by shaking at 25 ° C. for 2 hours, and then the insoluble matter (gel content) is precipitated by centrifugation (rotation speed 1000 to 14000 rpm, separation time 30 minutes). Then, the supernatant is removed by decantation to obtain a gel. Next, the swollen gel is pre-dried at 100 ° C. for 2 hours and then dried in a vacuum dryer at 120 ° C. for 1 hour. It was cooled to room temperature with a desiccator, weighed precisely, and calculated by the following formula.
Gel fraction (%) = ((ba) / S) x 100
a: Centrifugal sedimentation tube weight b: Dry gel + centrifugal sedimentation tube weight S: Sample resin weight

<Rubber polymer content>
Dissolve a styrene resin in chloroform, add a certain amount of iodine monochloride / carbon tetrachloride solution, leave it in the dark for about 1 hour, add 15% by mass potassium iodide solution and 50 ml of pure water, and add excess monochloride. Iodine was titrated with a 0.1 N sodium thiosulfate / ethanol solution and calculated from the amount of iodine monochloride added.

<Volume average particle size of rubber-like polymer>
The styrene resin was completely dissolved in dimethylformamide and measured with a laser diffraction type particle size distribution device. As a measuring device, a laser diffraction type particle analyzer "LS-230 type" manufactured by Beckman Coulter Co., Ltd. was used.

[(B) Flame Retardant]
As the flame retardant, "SAYTEX-8010" (decabromodiphenylethane) manufactured by Albemarle Japan Co., Ltd. was used. (Melting point: 345 ° C)

[(C) Flame retardant aid]
"PATOX-M" (antimony trioxide having a volume average particle diameter of 0.8 μm) manufactured by Nihon Seiko Co., Ltd. was used.

[(D) Talc]
"KP talc" (volume average particle size: 8 μm) manufactured by Fuji Talc Industry Co., Ltd. was used.

[Manufacturing of flame retardant masterbatch]
After premixing (A) styrene resin, (C) flame retardant aid, and (D) talc in the blending amounts (parts by mass) shown in Tables 1 and 2 with a Henschel mixer type mixer, FIG. A fixed amount was supplied to the first supply section of the twin-screw extruder shown. The flame retardant (B) was supplied at the supply positions and blending ratios shown in Tables 1 and 2. These raw materials were melt-kneaded in the first and second kneading portions to form strands, cooled with water, led to a pelletizer, and pelletized to obtain a flame retardant masterbatch. At the time of premixing, a mixture of sodium aluminosilicate and A-type zeolite, zinc stearate, polyethylene wax, and ethylene bisstearate amide were also added at the same time.

As the twin-screw extruder, "H-KTX30XHT" (screw diameter Φ30 mm, L / D = 46.8) manufactured by Kobe Steel, Ltd. was used. The cylinder set temperature is 190 ° C (conveyed part) to 220 ° C (kneading to measuring part) to 230 ° C (discharge port), and the discharge amount and screw rotation speed under other conditions are the conditions shown in Tables 1 and 2. It was carried out at. As for the resin temperature at the time of extrusion, the thermometer values installed on the downstream side of the second kneading portion and the discharge port are shown in Tables 1 and 2.

[Manufacturing of styrene-based flame-retardant resin composition]
The flame retardant masterbatch and styrene resin are premixed in the blending amounts (parts by mass) shown in Tables 1 and 2 with a Henshell mixer type mixer, then supplied to a single screw extruder and melt-kneaded. , Strands, water-cooled, led to a pelletizer, and pelletized to obtain a styrene-based flame retardant resin composition.

As the single-screw extruder, IKG's "PMS40-28" (screw diameter Φ40 mm, L / D = 28, dalmage screw) was used. The cylinder temperature was 180 ° C. (transportation site) to 200 ° C. (kneading to weighing site) to 230 ° C. (discharge port), and the screw rotation speed was 100 rpm.

〔Evaluation methods〕
The various measurements shown in Examples and Comparative Examples were carried out by the following methods. The results are shown in Tables 1 and 2.

<Dispersibility>
After heating and drying the pellets of the flame retardant masterbatch at 70 ° C for 3 hours in a press molding machine (“MP-2F” manufactured by Toyo Seiki Seisakusho Co., Ltd.), place about 100 g on the edge of the press plate to set the temperature to 200 ° C. The flame retardant masterbatch that had melted and protruded was slowly pulled by heating for 3 minutes, gradually applying pressure, and a film having a thickness of about 30 to 50 μm was prepared and visually observed. The evaluation results are described as follows.
○: No lumps ×: There are lumps with poor dispersion

(Flame retardance>
After the pellets of the styrene-based flame-retardant resin composition are heated and dried at 70 ° C. for 3 hours, the difficulty of 127 × 12.7 × 0.8 mm is obtained by an injection molding machine (“J100E-P” manufactured by Japan Steel Works, Ltd.). A test piece for flame evaluation was molded. Using such a test piece, a combustion test was conducted based on the vertical combustion test method (UL94) of Subject 94 of Underwriters Laboratories, Inc. of the United States.

(Scratch property>
Pellets of styrene-based flame-retardant resin composition are heated and dried at 70 ° C. for 3 hours, and then molded by an injection molding machine (“J100E-P” manufactured by Japan Steel Works, Ltd.) for a molding technician test (molded product dimensions). : Length / width / depth = 100 x 75 x 45 mm, box type) Cylinder temperature: 220 ° C, mold temperature: 40 ° C, cooling time: 40 seconds, injection speed: 10%, injection time: 6 seconds It was continuously molded. The scratches generated at the corners of the molded product when the mold was opened were visually observed. The evaluation results are described as follows.
○: No scratches ×: Scratches

1 Twin-screw extruder 2 1st supply part 3 2nd supply part 4 Vacuum vent port 5 Flame retardant masterbatch discharge port (die)
6 1st kneading part 7 2nd kneading part 8 Forward feed screw 9 Forward feed screw 10 Thermometer

Claims (9)

A method for manufacturing a flame retardant masterbatch using a twin-screw extruder.
The twin-screw extruder includes a plurality of raw material supply units for supplying the raw materials of the flame retardant masterbatch into a cylinder, a kneading unit provided on the downstream side of the raw material supply unit and kneading the raw materials, and the above. A progressive screw provided between the upstream side of the kneading portion and the kneading portion, a vacuum vent port provided on the downstream side of the kneading portion, and a kneading portion provided on the downstream side of the vacuum vent port. Equipped with an outlet for discharging the raw material kneaded in
A step of kneading the raw material supplied from the raw material supply unit in the kneading unit and discharging the raw material from the discharge port is provided.
The raw material contains a styrene resin and a flame retardant, and contains
The melting point of the flame retardant is higher than the maximum temperature between the kneading portion and the outlet.
The flame retardant is supplied into the cylinder from a source other than the most upstream raw material supply section among the plurality of raw material supply sections.
The L / D of the progressive screw on the upstream side of the kneading portion is 1.2 or less.
A method for producing a flame retardant masterbatch, wherein the L / D of the progressive screw between the kneading portions is 0.5 or more.
However, D is the screw diameter (mm), and L is the screw lead length (mm). With respect to the styrene-based resin 100 parts by weight, and the flame retardant 15 to 90 parts by weight, the production method of the flame retardant masterbatch according to claim 1. The method for producing a flame retardant masterbatch according to claim 1 or 2 , wherein the flame retardant is a brominated diphenylalkane represented by the formula (1).
[In the formula, R is an alkylene group of C _n H _2n (n is an integer of 1 to 10), X ₁ and X ₂ are bromine atoms of an integer 1 to 5, respectively, and X ₁ + X ₂ ≧ 2. ] The method for producing a flame retardant masterbatch according to claim 3 , wherein the brominated diphenylalkane is decabromodiphenylethane. The material further comprises, the production method of the flame retardant masterbatch according to any one of claims 1 to 4 the flame retardant aid and talc. The method for producing a flame retardant masterbatch according to claim 5 , wherein the flame retardant aid is 0 to 15 parts by mass and the talc is 0 to 40 parts by mass with respect to 100 parts by mass of the styrene resin. The method for producing a flame retardant masterbatch according to claim 5 or 6 , wherein the flame retardant aid is antimony trioxide. Comprises a flame retardant master batch was obtained by the method according to any one of claims 1 to 7, and a styrene-based resin composition, the step of melt-mixing in an extruder, a styrene-based flame retardant A method for producing a resin composition. A method for producing a molded product , which comprises a step of molding the styrene-based flame-retardant resin composition obtained by the method according to claim 8 .