JP6282928B2 - Method for producing styrene-based flame retardant resin composition - Google Patents

Description

  The present invention relates to a method for producing a styrene-based flame retardant resin composition containing a bromine-containing flame retardant.

  Styrenic resins are used in a wide range of applications that take advantage of their properties. In particular, flame retardant resins with high flame retardancy are used in a wide variety of fields, including office automation equipment such as word processors, personal computers, printers, and copiers, and home appliances such as LCD TVs, VTRs, and audio. Yes.

  Conventionally, various flame retardants have been proposed to impart flame retardancy to styrene-based resins, and among them, halogen-containing organic compounds that are inexpensive and have excellent physical property balance are often used. Typical examples include tetrabromobisphenol A, decabromodiphenyl ether, decabromodiphenylethane, brominated triazine, brominated epoxy, and brominated flame retardants in which the epoxy group of brominated epoxy resin is blocked with tribromophenol. It is preferably used. Among them, use of brominated triazine-based 2,4,6-tris (2,4,6-trisbromophenoxy) -1,3,5-triazine compound having a good balance between heat resistance and physical properties for flame-retardant resin Is increasing.

  However, when brominated triazine is blended in the resin composition as a flame retardant, an unpleasant odor may occur during resin processing and when the final product is unpacked. Such odors have problems such as not only reducing workability during resin processing, but also significantly reducing the commercial value of molded products.

  In Patent Document 1, a styrene-based resin as a raw material is divided, and after a part is melt-mixed with other components, the remaining styrene-based resin is added and the whole is melt-mixed to reach a resin composition. A production method is disclosed in which the maximum temperature is lowered to suppress the generation of odor due to thermal decomposition of the flame retardant.

JP 2011-11415 A

  In the production method described in Patent Document 1, the problem of odor of the styrene-based flame retardant resin composition containing the bromine-containing flame retardant was solved, but the resin and its resin were added to the strand outlet of the die part of the twin screw extruder. It has been found that “meani” occurs due to sticking or seizing of pyrolysates and additives. When the mains are mixed in the resin composition, the appearance of a molded product using the resin composition is deteriorated. For this reason, in the case of occurrence of a mess, there is a problem that maintenance work for stopping the continuous production line and removing dirt on the die part is required, and productivity is lowered.

  An object of the present invention is to provide a production method that suppresses the occurrence of scouring at the strand outlet of a die part when producing a styrene-based flame retardant resin composition containing a bromine-containing flame retardant using a twin screw extruder. It is in.

The method for producing a styrene-based flame retardant resin composition of the present invention uses a twin screw extruder having a land length of the die portion of less than 20 mm, and sets the shear rate at the die portion to 600 to 900 s ^−1. A modified styrene resin, (B) a bromine-containing flame retardant, (C) a flame retardant aid, and (D) zinc stearate are melt-mixed.

  According to the present invention, in the production of a styrene-based flame retardant resin composition in which a rubber-modified styrene resin and a bromine-containing flame retardant are uniformly melt-mixed using a twin-screw extruder, Can be suppressed. Therefore, it is possible to reduce the frequency of maintenance work of the twin-screw extruder for removing the mains and improve the productivity of the styrene-based flame retardant resin composition.

  In the present invention, the addition of the rubber-modified styrenic resin is divided into two portions to suppress the temperature rise of the resin composition during melt mixing, and the pyrolysis of the bromine-containing flame retardant in the resin composition is suppressed. Can be suppressed. Therefore, the decomposition product of the flame retardant, which is a cause of unpleasant odor, contained in the obtained styrene-based flame retardant resin composition is reduced, and odor generation from the final product is suppressed during resin processing. The

It is a schematic diagram which shows the structure of the twin-screw extruder preferably used for this invention. It is a cross-sectional schematic diagram along the extrusion direction of the die part of the twin-screw extruder used for this invention.

The feature of the present invention is that when the raw material (A) rubber-modified styrene resin, (B) bromine-containing flame retardant, and (C) flame retardant aid are put into a twin screw extruder and mixed, (D) using zinc stearate as an agent, using a twin screw extruder with a land length of the die portion of less than 20 mm, and setting the shear rate in the die portion of the twin screw extruder to 600 to 900 s ⁻¹ is there.

  The present invention is described in detail below.

The (A) rubber-modified styrenic resin used in the present invention is, for example, a rubber-like polymer dissolved in a mixed liquid of an aromatic vinyl monomer and an inert solvent, and stirred, bulk polymerization, suspension polymerization, solution It refers to a polymer obtained by dispersing a rubbery polymer in the form of particles in an aromatic vinyl polymer matrix obtained by polymerization or the like. Although there is no restriction | limiting in particular about the molecular weight of a matrix part, 0.55-0.85 is suitable at a reduced viscosity ((eta) _sp / C). If it exceeds 0.85, the fluidity of the resin composition is too low to hinder molding, and if it is less than 0.55, there is a problem that practically sufficient strength cannot be exhibited. Although there is no restriction | limiting in particular about rubber content, 5-15 mass% generally used for rubber-modified styrene-type resin is suitable. The rubber content is preferably determined in consideration of the balance between impact strength and rigidity necessary for the molded product. Although there is no restriction | limiting in particular about the volume average particle diameter of a rubber-like polymer, Generally it is 0.4-6.0 micrometers, Preferably 0.5-3.0 micrometers is suitable. If the rubber particle diameter is too small, the impact resistance strength is drastically lowered, and if the particle diameter is too large, the appearance such as surface gloss of the molded product tends to deteriorate.

  The aromatic vinyl monomer mentioned above is mainly styrene. Although o-methyl styrene, m-methyl styrene, p-methyl styrene, 2,4-dimethyl styrene, and the like, and combinations thereof can be mentioned, styrene is most preferable.

  Examples of the rubber-like polymer include polybutadiene, styrene-butadiene copolymer, polyisoprene and the like, and among them, polybutadiene and styrene-butadiene copolymer are preferable.

  The brominated flame retardant (B) used in the present invention is preferably a brominated aromatic triazine compound having a melting point of 200 to 260 ° C., particularly 2,4,6-tris (2,4,6- Tribromophenoxy) -1,3,5-triazine.

  Furthermore, the (C) flame retardant aid used in the present invention functions to further enhance the flame retardant effect of the (B) bromine-containing flame retardant, such as antimony trioxide, antimony tetroxide, and pentoxide. Antimony, antimony oxide such as sodium antimonate, zinc borate, barium metaborate, anhydrous boric acid, boric compounds such as anhydrous boric acid, tin compounds such as zinc stannate and zinc hydroxystannate, molybdenum oxide, molybdenum Examples thereof include molybdenum compounds such as ammonium acid, zirconium compounds such as zirconium oxide and zirconium hydroxide, and zinc compounds such as zinc sulfide. Among these, antimony trioxide is preferably used.

  In the present invention, (D) zinc stearate is used as a dispersant in addition to (A) the rubber-modified styrene resin, (B) the bromine-containing flame retardant, and (C) the flame retardant aid. When a compound other than zinc stearate is used as the dispersing agent, the effect of suppressing the mains cannot be obtained.

  In the present invention, the blending amounts of (A) to (D) are preferably (B) 5 to 30 parts by mass, (C) 0.5 to 5 parts by mass, and (A) 100 parts by mass. D) 0.1 to 5 parts by mass.

  In addition, in this invention, in the range which does not impair the objective of this invention, addition of components other than said (A)-(D), for example, a plasticizer, a lubricant, a stabilizer, a ultraviolet absorber, a filler, a reinforcing agent, etc. An agent can be added.

In the present invention, when the raw materials (A) to (D) are charged into the twin screw extruder used for melt mixing and melt mixed, the shear rate at the die portion of the twin screw extruder is set to 600 to 900 s ^{-1 is} assumed. Moreover, the twin-screw extruder below 20 mm is used as the land length of the die part.

FIG. 2 shows a schematic cross-sectional view of the die portion. In the cross section along the extrusion direction of the resin composition, the die portion 7 of the twin-screw extruder used in the present invention is from the inlet side on the right side of the paper to the outlet on the left side of the paper (strand outlet 8) as shown in FIG. On the other hand, the cross-sectional area perpendicular to the extrusion direction is reduced. And in this invention, the length (land length) t of the land which is a channel | path of the resin composition by the side of the strand exit 8 shall be less than 20 mm. When the land length t is 20 mm or more, a sag is generated even if the shear rate is set to 600 to 900 s ⁻¹ , which is not preferable.

In addition, in the melt mixing of the resin composition, the higher the shear rate, the better the mixing and dispersion, and a stable and uniform resin composition can be obtained. If it is higher and the shear rate exceeds 900 s ⁻¹ , it is difficult to obtain the effect of preventing the occurrence of scum. Further, if the shear rate is less than 600 ⁻¹ , the effect of preventing the occurrence of scum is obtained, but the dispersibility is lowered and the resin composition becomes inferior in flame retardancy. In the present invention, by setting the shear rate to 600 to 900 s ⁻¹ , it is possible to stably produce a resin composition having high flame retardancy without generating a spear. The shear rate in the die part is obtained by the following formula.

Shear rate (s ⁻¹ ) = 4Q / πr ³
Q: Volume flow rate ratio (mm ³ / s) = πd ² S / 60
S: extrusion speed (mm / min) = discharge amount (kg / h) /0.0153388
d: Die portion entrance radius (mm)
r: Die part exit radius (mm)

  In the present invention, the above (A) to (D) may be melt-mixed at one time, but (A) a part of the rubber-modified styrene resin and (B) to (D) are first melt-mixed, The remaining (A) rubber-modified styrenic resin is charged and the whole is melt-mixed, so that the resin temperature that reaches the maximum at the exit of the twin-screw extruder can be lowered and the generation of odors can be suppressed. it can.

  FIG. 1 is a diagram schematically showing the configuration of a twin screw extruder preferably used in the present invention, in which 1 is a twin screw extruder, 2 is a first raw material inlet, and 3 is a second raw material inlet. Mouth, 4 is a first vacuum vent, 5 is a second vacuum vent, 6 is a kneading disk, 7 is a die portion, and 8 is a strand outlet which is a discharge port for the resin composition. In FIG. 1, the right side of the drawing is upstream and the left side is downstream. The dice portion 7 has the cross-sectional structure shown in FIG.

  When (A) to (D) are melted and mixed at a time, (A) to (D) are arranged between the first raw material inlet 2 or the first raw material inlet 2 and the first vacuum vent 4. Are put into the twin screw extruder 1 and melted and mixed uniformly. In this case, even if all the components are introduced from the first raw material inlet 2, some constituent components are introduced from the first raw material inlet 2, and the remaining constituent components are supplied from the first raw material inlet 2 to the first raw material inlet 2. Side feed may be performed up to one vacuum vent 4. For example, (A) is charged from the first raw material inlet 2, and (B), (C), and (D) are partially charged from the first raw material inlet 2 together with (A). A form of side-feeding is also preferably applied.

  When (A) is divided into two and melt-mixed with (B) to (D), the twin-screw extruder 1 is from the upstream side between the first raw material inlet 2 and the strand outlet 8. , At least a first vacuum vent 4, a second raw material inlet 3, a kneading disk 6, and a second vacuum vent 5.

  First, a part (A-1), (B), (C), and (D) of (A) is transferred from the first raw material inlet 2 or the first raw material inlet 2 to the first vacuum vent 4. During this time, it is put into an extruder and uniformly melted and mixed to obtain a first mixture. Then, the remainder (A-2) of (A) is charged from the second raw material charging port 3, added to the first mixture, and melted and mixed uniformly again. A composition is obtained.

  In the present invention, as described above, by introducing (A-2) from the second raw material inlet 3, it is possible to reduce the temperature of the first mixture whose temperature has already been increased by melt mixing. The maximum resin temperature at the strand outlet 8 of the resin composition of the twin-screw extruder 1 can be greatly reduced as compared with the conventional case. In addition, (A-1), (B), (C), and (D) constituting the first mixture may be melted and mixed uniformly before adding (A-2), and all the components are mixed. Even if charged from the first raw material charging port 2, some components are charged from the first raw material charging port 2, and the remaining components are transferred from the first raw material charging port 2 to the first vacuum vent 4. You may side feed between. For example, (A-1) is introduced from the first raw material inlet 2, and (B), (C), and (D) are partially fed from the first raw material inlet 2 together with (A-1). A mode in which the charging is performed and the remaining part is side-feeded is also preferably applied.

  In the present invention, the mass ratio of (A-1) and (A-2) obtained by dividing (A) into two is (A-1) / (A-2) = 45/55 to 85/15. When the mass ratio of (A-2) is lower than 15% by mass, the temperature lowering effect of the mixture is not sufficient, and when it exceeds 55% by mass, (A-2) and the first mixture are combined. It becomes impossible to melt and mix sufficiently uniformly.

  The twin-screw extruder 1 is charged with (A-2) after the vaporized components are removed from the first mixture in the first vacuum vent 4, and then a relatively large amount of (A-2) is back-flowed (vented up). ), The kneading disk 6 needs to be disposed after the charging (A-2). When the cylinder inner diameter of the twin-screw extruder 1 is D and the distance from the first vacuum vent 4 to the kneading disk 6 is L1, L1 / D ≧ 5.4. In addition, L1 means the distance from the center part of the 1st vacuum vent 4 to the upstream front-end | tip of the kneading disc 6 in the length direction of the twin-screw extruder 1 as shown in FIG. In addition, if the distance from the first vacuum vent 4 to the kneading disk 6 is too long, uniform mixing failure of the first mixture of (A-2) is likely to occur, and therefore preferably L1 / D ≦ 9. .0.

  Further, L2 / D, which is a ratio of the length L2 of the kneading disk 6 and the above D, is preferably 2.5 to 3.0.

As described above, if the compositions of (A) to (D) are the same, by dividing (A) and feeding it into a twin-screw extruder, the maximum resin temperature is lowered to a bromine-containing flame retardant. Occurrence of the resulting odor can be suppressed. In this case, by setting the shear rate of the die part of the twin-screw extruder to 600 to 700 s ⁻¹ , it is possible to surely obtain a high mean suppressing effect and odor generating effect. This is preferable.

  In the twin-screw extruder 1 of FIG. 1, it is preferable that other elements are appropriately disposed between the kneading disk 6 and the second vacuum vent 5. Specifically, a full flight screw, a notch screw are provided. It is desirable to arrange elements, three-blade rotor segments and the like in combination as necessary.

  Conventionally, when a styrene-based flame retardant resin composition is produced using a bromine-containing flame retardant, it has occurred in the process of processing a molded product using the resin composition and the final product after processing Odor is due to the fact that a component produced by thermal decomposition of a bromine-containing flame retardant in the process of producing a styrene-based flame retardant resin composition is contained in the resin composition. That is, in the process of adding a flame retardant, a flame retardant aid, and a dispersant to a rubber-modified styrene resin, and uniformly melting and mixing with a twin screw extruder or the like, the temperature of the mixture rises and the melting point of the flame retardant is increased. When exceeding, a part of flame retardant will thermally decompose. Since the styrene-based flame retardant resin composition obtained in the process includes a component generated by thermal decomposition of the flame retardant, the component is used when molding a molded product using the resin composition. It becomes odor and is emitted to the outside.

  In the present invention, among the components constituting the resin composition, (A) only the rubber-modified styrenic resin is divided into two parts, and after part of the components are uniformly melt-mixed with the other components (B) to (D), (A) By adding a rubber-modified styrenic resin and uniformly melting and mixing, the temperature rise of the mixture in the uniform melt mixing step is suppressed, and multiple components can be uniformly melt mixed in a lower temperature range than before. it can. Therefore, even if the resin composition in the conventional twin screw extruder has exceeded the melting point of the flame retardant, it can be kept below the melting point of the flame retardant, and the thermal decomposition of the flame retardant is suppressed. can do. Therefore, generation | occurrence | production of the odor at the time of the shaping | molding process of the styrene-type flame retardant resin composition finally obtained and a molded article is suppressed.

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

[(A) Rubber-modified styrene resin]
The characteristics and configuration of the rubber-modified styrene resin (A) used in this example are as follows.
Reduced viscosity: 0.81 dl / g
Rubbery polymer content: 8.8% by mass
Gel content: 23.7 mass%
Volume average particle diameter of rubber particles: 2.5 μm

  The reduced viscosity, gel content, rubbery polymer content and average particle size referred to here were measured by the following methods.

<Reduced viscosity (η _sp / C)>
(A) A mixed solvent of 15 ml of methyl ethyl ketone (MEK) and 15 ml of acetone is added to 1 g of rubber-modified styrenic resin, and dissolved by shaking at 25 ° C. for 2 hours. The resin component was precipitated by adding 500 ml of methanol and dried. The resin component obtained by the same operation was dissolved in toluene to prepare a sample solution having a polymer concentration of 0.4% (mass / volume). This sample solution and pure toluene were kept constant at 30 ° C., the solution flow seconds were measured with an Ubbelohde viscometer, and the following formula was calculated.

η _sp / C = (t1 / t0-1) / C
η _sp : Specific viscosity t0: Pure toluene flow seconds t1: Sample solution flow seconds C: Polymer concentration

<Gel content>
(A) A rubber-modified styrenic resin is added to toluene at a ratio of 2.5% by mass, dissolved by shaking at 25 ° C. for 2 hours, and then insoluble by centrifugation (rotation speed: 10,000 to 14000 rpm, separation time 30 minutes). (Gel content) was allowed to settle, and the supernatant was removed by decantation to obtain a swollen gel. Next, this swollen gel was preliminarily dried at 100 ° C. for 2 hours, and then dried in a vacuum dryer at 120 ° C. for 1 hour. It cooled to normal temperature with the desiccator, weighed precisely, and computed with the following formula.

Gel content (%) = ((ba) / S) × 100
a: Mass of centrifugal sedimentation tube b: Dry gel + mass of centrifugal sedimentation tube S: Mass of sample resin

<Rubber polymer content>
(A) A rubber-modified styrene-based resin is dissolved in chloroform, a certain amount of iodine monochloride / carbon tetrachloride solution is added, and the mixture is left in a dark place for about 1 hour, and then a 15% by mass potassium iodide solution and 50 ml of pure water are added. In addition, excess iodine monochloride was titrated with 0.1N sodium thiosulfate / ethanol aqueous solution and calculated from the amount of iodine monochloride added.

<Volume average particle diameter of rubbery polymer>
(A) The rubber-modified styrene resin was completely dissolved in dimethylformamide and measured with a laser diffraction particle size distribution device (Laser diffraction particle analyzer LS-230, manufactured by Coulter).

[(B) Bromine-containing flame retardant]
“SR245” (2,4,6-tris (2,4,6, -tribromophenoxy) -1,3,5-triazine compound) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was used.

[(C) Flame retardant aid]
“PATOX-M” (antimony trioxide having an average particle diameter of 0.8 μm) manufactured by Nippon Seiko Co., Ltd. was used.

[Dispersant]
(D) “Zinc stearate G” manufactured by NOF Corporation was used as zinc stearate.

The dispersants used in the comparative examples are as follows.
Calcium stearate: NOF Corporation "Calcium stearate G"
Magnesium stearate: “Magnesium stearate G” manufactured by NOF Corporation
Sodium stearate: Showa Chemical Co., Ltd. “Sodium stearate”

[Twin screw extruder]
“H-KTX-30XHT” manufactured by Kobe Steel, Ltd. was used. The configuration is as shown in FIG. 1, and the specifications and setting conditions are as follows. As the die portion 7, a three-hole die was used, and two types having a land length of 15 mm and a land length of 25 mm were used.

Screw diameter Φ: 30mm
Cylinder inner diameter D: 32mm
Die portion entrance radius d: 5 mm
Die part exit radius r: 1.8 mm
Land length t: 15mm, 25mm
L1 / D = 7.2
L / D = 53 (L is the total length of the screw including the kneading disk 6 of the twin screw extruder)
Kneading disk 6: A kneading element having a phase angle of 45 ° and a phase angle of 90 ° was combined and L2 / D was 3.0.
Cylinder set temperature: 180 ° C. (conveying part) to 200 ° C. (kneading to measuring part)

〔Evaluation method〕
The evaluation methods in the examples are as follows.

<Meani property>
After extruding a certain amount with the twin-screw extruder 1, it was visually observed and judged whether or not a spear was generated at the strand outlet 8 of the die part 7. Judgment criteria are as follows.
A: Meani was not observed at all.
○: Some scouring was observed.
X: Meani was observed at a problematic level.

<Resin temperature>
The temperature of the resin composition at the strand outlet 8 of the die part 7 of the twin screw extruder 1 was measured. The temperature measured here is the maximum temperature reached by the resin composition.

<Flame retardance>
The pellet of the styrene-based flame retardant resin composition is heated and dried at 70 ° C. for 3 hours, and then is 127 × 12.7 × 0.8 mm with an injection molding machine (“J100E-P” manufactured by Nippon Steel) A test piece for flammability evaluation was molded. Using such a test piece, a combustion test was performed based on the subject No. 94 vertical combustion test method (UL94) of US Underwriters Laboratories.

<Odor sensory test>
A 10 g sample was placed in a 50 ml screw-cap sample bottle, sealed, and heated in an oven at 60 ° C. for 20 minutes, and a sensory tester dedicated to the intensity of odor was judged and subjected to relative evaluation.
Odor relative comparison judgment ×: Strong ○: Weak (substantially no effect)

(Examples 1-3, Comparative Examples 1-3)
(A) The rubber-modified styrenic resin, (C) the flame retardant aid, and the dispersant were premixed with a mixer-type mixer at the blending ratio shown in Table 1, and then the twin-screw extruder 1 shown in FIG. The first raw material inlet 2 is charged, and (B) a bromine-containing flame retardant is side-fed between the first raw material inlet 2 and the first vacuum vent 4 to form a styrene flame retardant resin composition. Got. The land length t of the die part 7 of the twin-screw extruder 1 was 15 mm, the discharge rate was 32.2 kg / h, and the shear rate of the die part was 600 s ⁻¹ . Table 1 shows the blending amounts and evaluation results of each example.

  As shown in Table 1, the use of zinc stearate as a dispersant successfully prevented the occurrence of scum.

(Examples 4 and 5, Comparative Examples 4 and 5)
The discharge rate of the twin screw extruder 1 is 37.6 kg / h, 48.3 kg / h, 26.8 kg / h, and 53.7 kg / h, and the shear rate of the die part is 700 s ⁻¹ , 900 s ⁻¹ , 500 ^{− A} styrene-based flame retardant resin composition was produced and evaluated in the same manner as in Example 1 except that ¹ and 1000 s ⁻¹ were changed. The evaluation results of each example are shown in Table 2.

(Comparative Examples 6 and 7)
Styrenic flame retardant resin compositions were produced and evaluated in the same manner as in Examples 1 and 5 except that the die portion 7 having a land length of 25 mm was used for the twin screw extruder 1. The evaluation results of each example are shown in Table 2.

(Examples 6 to 8, Comparative Examples 8 and 9)
Examples 6 to 8 and Comparative Examples 8 and 9 were carried out at the same blending ratio as in Example 1. In each example, (A) 70 parts by mass of rubber-modified styrenic resin (A-1), (C) flame retardant aid, and (D) zinc stearate were premixed in a mixer-type mixer, and then shown in FIG. (1) The bromine-containing flame retardant is side-fed between the first raw material inlet 2 and the first vacuum vent 4; The remaining 30 parts by mass (A-2) of the (A) rubber-modified styrenic resin was charged from the second raw material charging port 3 to obtain a styrene-based flame retardant resin composition. Further, the discharge rate of the twin screw extruder 1 is 32.2 kg / h, 37.6 kg / h, 48.3 kg / h, 26.8 kg / h and 53.7 kg / h, and the shear rate of the die part is 600 s ^{−. 1, 700s -1, 900s -1,} 500s -1, and it was 1000 s ^-1. The evaluation results of each example are shown in Table 2.

(Comparative Examples 10 and 11)
Styrenic flame retardant resin compositions were produced and evaluated in the same manner as in Examples 6 and 8, except that the die part 7 having a land length of 25 mm was used in the twin-screw extruder 1. The evaluation results of each example are shown in Table 2.

(Comparative Examples 12 and 13)
A styrene flame retardant resin composition was produced and evaluated in the same manner as in Examples 6 and 7 except that the blending ratio was the same as in Comparative Example 1. The evaluation results for each example are shown in Table 3.

As is clear from Tables 2 and 3, it was found that if the shear rate is the same, the lower the shear rate, the higher the effect of preventing the occurrence of cracking, but if the shear rate is less than 600 s ⁻¹ , the flame retardancy is inferior. Moreover, even if it mixed with the same composition and the same shear rate, when the (A) was divided | segmented and thrown in, the maximum resin temperature became low and it turned out that generation | occurrence | production of an odor is suppressed. Furthermore, when the land length of the die part is 20 mm or more, it has been found that in any case, the effect of preventing the occurrence of scratches cannot be obtained. Furthermore, when (A) is divided and added, by setting the shear rate of the die part to 600 s ^{-1 to} 700 s ^-1 , it is possible to obtain the effects of preventing occurrence of scum and suppressing odor generation at a higher level. all right.

  1: twin screw extruder, 2: first raw material inlet, 3: second raw material inlet, 4: first vacuum vent, 5: second vacuum vent, 6: kneading disc, 7: die Part 8: Strand exit

Claims (6)

Using a twin-screw extruder having a land length t of the die portion of less than 20 mm and setting the shear rate in the die portion to 600 to 900 s ⁻¹ , (A) a rubber-modified styrene resin, (B) a bromine-containing flame retardant, ( A method for producing a styrene-based flame-retardant resin composition, which comprises melt-mixing C) a flame retardant aid and (D) zinc stearate.   The method for producing a styrene-based flame retardant resin composition according to claim 1, wherein the brominated flame retardant (B) is a brominated aromatic triazine compound having a melting point of 200 to 260 ° C.   3. The styrenic difficulty according to claim 2, wherein the brominated aromatic triazine compound is 2,4,6-tris (2,4,6-tribromophenoxy) -1,3,5-triazine. A method for producing a flammable resin composition. Between the first raw material charging port located at the upstream end portion and the resin composition outlet port located at the downstream end portion, the twin screw extruder from the upstream side, the first vacuum vent, It has at least a second raw material inlet, a kneading disk, and a second vacuum vent, the inner diameter of the cylinder of the twin screw extruder is D, and the distance from the first vacuum vent to the kneading disk is L1 L1 / D ≧ 5.4, and
45 to 85% by mass (A-1), (B), (C), and (D) of (A) are supplied from the first raw material inlet or the first raw material inlet to the first vacuum vent. In the meantime, the mixture is put into a twin screw extruder and homogeneously melted and mixed, and then the remaining 55 to 15% by mass (A-2) of the above (A) is introduced from the second raw material inlet and uniformly melted and mixed. The manufacturing method of the styrene-type flame retardant resin composition of any one of Claims 1 thru | or 3 characterized by the above-mentioned. The said shear rate is 600-700 s < ^-1 >, The manufacturing method of the styrene-type flame retardant resin composition of Claim 4 characterized by the above-mentioned.   The said L1 / D is 9.0 or less, The manufacturing method of the styrene-type flame retardant resin composition of Claim 4 or 5 characterized by the above-mentioned.

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