KR101473776B1 - Flame Retardant Thermoplastic Resin Composition Having Improved Environmental Stress Cracking Resistance - Google Patents

Abstract

The present invention relates to a polyphenylene ether-based flame retardant thermoplastic resin composition comprising a polyphenylene ether resin, a rubber-modified polystyrene resin, a styrene-based thermoplastic elastomer, a polyvinyl butyral resin and a flame retardant.
The flame retardant thermoplastic resin composition according to the present invention has excellent mechanical properties such as strength and flame retardancy, and even when a small amount of polyvinyl butyral resin is used, resistance against external stress cracking is improved compared to conventional materials, And can be usefully applied to electronic parts manufacturing.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a flame retardant thermoplastic resin composition having improved external stress cracking resistance,

The present invention relates to a resin composition having excellent flame retardancy and improved resistance to external stress cracking as compared with conventional materials, and relates to a polyphenylene ether-based flame retardant thermoplastic resin composition containing a polyvinyl butyral resin and a flame retardant in a polyphenylene ether resin .

The polyphenylene ether resin is an engineering plastic material having excellent electrical properties, heat resistance, dimensional stability, low moisture absorption rate and creep property at high temperature, and is widely used for electric / electronic parts and automobile parts requiring precise dimensions. In recent years, a variety of research and development has been attempted, such as replacing automotive shell plates made of steel and achieving weight reduction and energy reduction.

However, since the polyphenylene ether resin has a high melt viscosity and poor moldability, solvent resistance and impact resistance are low, there is a problem in injection moldability and appearance of the molded article when applied alone. Therefore, mixing with a compatible / incompatible resin such as polystyrene The product that compensates for these drawbacks is being applied to the market.

However, a combination of a polyphenylene ether resin and a polystyrene resin causes a phenomenon in which the impact resistance is decreased while the workability is improved. Therefore, a method of improving the mechanical properties by adding a rubber-modified polystyrene resin is known.

However, these polyphenylene ether resins are limited to the use of reservior, containers, and cables that are exposed to stress for a long time due to environmental stress cracking (ESC) when they are exposed to a certain chemical environment for a long time. There is a drawback to follow.

In order to solve these drawbacks, U.S. Patent No. 4529761 has attempted to improve environmental stress cracking resistance (ESCR) by partially applying an alkyl or aralkyl sulfonate, which is an antistatic agent, And a large amount of expensive antistatic agent must be used.

In addition, U.S. Patent No. 4668723 discloses a method for partially improving ESCR characteristics of a polyphenylene ether resin composition using bis-maleimide or divinylbenzene having a polyfunctional group, There is a problem that it is not suitable for general injection molded articles because the melt stress is increased and the fluidity is lowered during injection molding and the quality of the molded article is deteriorated.

In addition, Korean Patent Publication No. 2010-0033540 discloses a method of increasing ESCR by mixing an impact modified monovinylidene aromatic polymer with a small amount of an ethylene / alpha-olefin (EAO) copolymer, The present invention has the disadvantage that it improves the ESCR characteristic over time and the Izod impact resistance to some extent by improving the elongation at break but is insufficient to satisfy chemical resistance and flame retardancy.

As described above, various methods for improving the ESCR properties have been proposed. However, development of a resin satisfying various properties required for engineering plastic materials such as ESCR properties, mechanical properties and heat resistance has not yet been developed.

A problem to be solved by the present invention is to provide a polyphenylene ether resin composition which is excellent in mechanical strength and flame retardancy while improving external stress cracking resistance.

In order to solve the above problems, the present invention provides a polyphenylene ether composition comprising 20 to 70% by weight of a polyphenylene ether; 10 to 40% by weight of a rubber-modified polystyrene resin composed of a copolymer of a styrene-based monomer and a monomer copolymerizable with a styrene-based monomer, or a styrene-based graft copolymer; Polystyrene-polyisoprene diblock copolymer, polystyrene-polyisoprene diblock copolymer, poly alpha methyl styrene-polybutadiene diblock copolymer, polystyrene-polybutadiene-polystyrene triblock copolymer, polystyrene-polyisoprene-polystyrene triblock copolymer, - at least one styrenic thermoplastic resin selected from the group consisting of polyalpha methylstyrene triblock copolymers, poly alpha methylstyrene-polyisoprene-polyalpha methylstyrene triblock copolymers and hydrogenated block copolymers thereof, 1 to 20% by weight of a block copolymer of an elastomer; 0.01 to 7.00% by weight of a polyvinyl butyral resin; And 1 to 20% by weight of a flame retardant; and a flame retardant thermoplastic resin composition with improved external stress cracking resistance.

At this time, the polyphenylene ether is preferably a compound represented by the following general formula (1).

[Chemical Formula 1]

(Wherein R ₁ to R ₄ each independently represent a hydrogen-substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a hydrogen-substituted or unsubstituted haloalkyl group having 1 to 30 carbon atoms, a hydrogen-substituted or unsubstituted carbon number 1 A substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a hydrogen-substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms, a hydrogen atom substituted or not substituted with hydrogen, a substituted or unsubstituted amino group having 1 to 30 carbon atoms, A substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms)

The polyphenylene ether may be selected from the group consisting of poly (2,6-dimethyl-1,4-phenylene) ether, poly (2,6- Poly (2,6-diallyl-1,4-phenylene) ether, poly (2, 6-dibutyl- Methyl-6-tolyl-1,4-phenylene) ether, poly (2-methyl- (2-methyl-6-butyl-1,4-phenylene) ether, poly (2,6-diethoxy-1,4-phenylene) ether, poly (2,6-dimethoxy-1,4-phenylene) (2,6-dimethyl-1,4-phenylene) ether and poly (2,3,6-trimethyl-1,4-phenylene) ether And a copolymer of poly (2,6-dimethyl-1,4-phenylene) ether and poly (2,3,5,6-tetramethyl-1,4-phenylene) ether Preferably at least one is chosen, and it is preferable that the intrinsic viscosity of from 25 ℃ chloroform solvent, 0.1 ~ 0.9 ㎗ / g.

The styrenic monomer may be styrene,? -Methylstyrene, or p-methylstyrene. The monomer copolymerizable with the styrenic monomer may be acrylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, methacrylic acid Maleic anhydride, methyl methacrylate, maleimide or N-phenylmaleimide, and the styrene graft copolymer may be an impact-resistant polystyrene resin, an acrylonitrile-butadiene-styrene resin, an acrylonitrile-butadiene- - a resin substituted with propylene rubber, and an acrylonitrile-acrylate-styrene resin.

The styrenic thermoplastic elastomer preferably further comprises an oil.

The polyvinyl butyral resin preferably has a melt index of 1 to 20 g / 10 min (230 DEG C, 2.16 kg) based on ASTM D 1238.

The flame retardant is preferably a mixture of an aromatic polyphosphate and a melamine polyphosphate.

The flame retardant thermoplastic resin composition according to the present invention has excellent mechanical properties such as strength and flame retardancy, and even when a small amount of polyvinyl butyral resin is used, resistance against external stress cracking is improved compared to conventional materials, And can be usefully applied to electronic parts manufacturing.

The polyphenylene ether resin composition of the present invention comprises 20 to 70% by weight of polyphenylene ether, 10 to 40% by weight of a rubber-modified polystyrene resin, 1 to 20% by weight of a styrenic thermoplastic elastomer, 0.01 to 7.00% by weight of a polyvinyl butyral resin, And 1 to 20% by weight of a flame retardant.

Hereinafter, the resin composition according to the present invention will be described in more detail.

The polyphenylene ether is preferably a compound represented by the following general formula (1).

(Wherein R ₁ to R ₄ each independently represent a hydrogen-substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a hydrogen-substituted or unsubstituted haloalkyl group having 1 to 30 carbon atoms, a hydrogen-substituted or unsubstituted carbon number 1 A substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a hydrogen-substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms, a hydrogen atom substituted or not substituted with hydrogen, a substituted or unsubstituted amino group having 1 to 30 carbon atoms, A substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms)

Specific examples of the polyphenylene ether include poly (2,6-dimethyl-1,4-phenylene) ether, poly (2,6-diethyl- Poly (2,6-dibutyl-1,4-phenylene) ether, poly (2,6- Methyl-6-tolyl-1,4-phenylene) ether, poly (2-methyl- Phenyl) ether, poly (2-methyl-6-butyl-1,4-phenylene) ether, Phenyl-1,4-phenylene) ether, poly (2,6-dimethoxy-1,4-phenylene) ether, poly (2,6-diethoxy- (2,6-dimethyl-1,4-phenylene) ether and poly (2,3,6-trimethyl-1,4-phenylene) ether, Ether and a copolymer of poly (2,6-dimethyl-1,4-phenylene) ether and poly (2,3,5,6-tetramethyl-1,4-phenylene) Although in the number of the selected at least one, but not the polyphenylene ether of the present invention is necessarily limited thereto.

The polyphenylene ether may be a copolymer of poly (2,6-dimethyl-1,4-phenylene) ether and poly (2,3,6-trimethyl-1,4-phenylene) -Dimethyl-1,4-phenylene) ether is more preferable, and it is most preferable to use poly (2,6-dimethyl-1,4-phenylene) ether.

The polyphenylene ethers may be used singly or in a mixture of two or more of them at an appropriate ratio.

The polymerization degree or molecular weight of the polyphenylene ether is not particularly limited. However, considering the thermal stability and workability of the thermoplastic resin composition, it is preferable that the polyphenylene ether has an intrinsic viscosity of 0.1 to 0.9 dl / g as measured in a chloroform solvent at 25 캜 , More preferably from 0.3 to 0.6 dl / g.

When the intrinsic viscosity is less than 0.1 dl / g, the molecular weight is low and the fluidity is improved. However, due to the decrease in heat resistance, it is difficult to secure smooth mechanical properties such as gas generation on the outer surface of the molded article, and the intrinsic viscosity exceeds 0.9 dl / g The fluidity is lowered, and injection pressure and temperature increase during injection molding, and the amount of deformation in the molded article increases.

The polyphenylene ether resin is preferably contained in an amount of 20 to 70% by weight based on the total composition. If the content is less than 20% by weight, the mechanical properties and heat resistance are deteriorated. If the content is more than 70% by weight, Which is undesirable because of decomposition by temperature.

Examples of the rubber-modified polystyrene resin include a copolymer of a styrene-based monomer and a monomer copolymerizable with a styrene-based monomer, or a styrene-based graft copolymer.

Examples of the styrene-based monomer include styrene,? -Methylstyrene, p-methylstyrene and the like, among which styrene is preferable.

Examples of the monomer copolymerizable with the styrene monomer include vinyl monomers such as vinyl monomers such as acrylonitrile and methacrylonitrile, vinyl monomers such as (meth) acrylic acid alkyl ester monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate and ethyl methacrylate , Maleimide, and N-phenylmaleimide. Of these, vinyl cyanide monomer and alkyl (meth) acrylate monomer are preferable.

Examples of the copolymer of the styrene monomer and the monomer copolymerizable with the styrene monomer include an acrylonitrile-styrene resin (AS resin), and examples of the styrene graft copolymer include an impact-resistant polystyrene resin (HIPS resin) Acrylate-styrene resin (AAS resin), a resin obtained by substituting butadiene of an ABS resin with an ethylene-propylene rubber (AES resin), and an acrylonitrile-acrylate-styrene resin .

Examples of the method for producing the styrenic copolymer include known methods such as emulsion polymerization, solution polymerization, suspension polymerization and bulk polymerization.

The rubber-modified polystyrene resin is preferably contained in an amount of 10 to 40 wt% based on the total weight of the composition. If the content is less than 10 wt%, the processability, impact properties, and chemical resistance deteriorate. When the content is more than 40 wt% Heat resistance and mechanical properties are deteriorated.

The styrenic thermoplastic elastomer of the present invention is derived from a vinyl aromatic monomer and may be a block or a triblock copolymer in the form of AB, ABA or ABC, and may be obtained by copolymerization of a vinyl aromatic monomer with hydrogenation, partial hydrogenation or hydrogen addition And a block of an unsaturated diene.

Examples of AB diblock type block copolymers include polystyrene-polyisoprene copolymers, polyalpha methylstyrene-polybutadiene copolymers and their hydrogenated forms, and such AB diblock copolymers are commercially well known Kraton D and Kraton G of Kraton and Solprene and K-resin of Philips are examples.

Examples of the ABA type triblock copolymer used as the styrene-based thermoplastic elastomer in the present invention include polystyrene-polybutadiene-polystyrene, polystyrene-polyisoprene-polystyrene, polyaramethylstyrene-polybutadiene- Alpha methyl styrene-polyisoprene-poly alpha methyl styrene, and hydrogenated forms thereof.

The styrenic thermoplastic elastomer used in the present invention may further comprise a commonly used oil. The oil is classified into paraffinic, naphthenic and aromatic oils according to the constituents, and in the present invention, paraffinic oils having favorable light resistance and weatherability It is more preferable to use oil.

In general, the oil input can be carried out indirectly by using the dielectric grade of the oil, by pre-kneading the styrene thermoplastic elastomer and the oil, or by directly introducing the oil into the apparatus for producing the thermoplastic elastomer. The content is preferably 50 to 3000 parts by weight, more preferably 100 to 1000 parts by weight, per 100 parts by weight of the elastomer.

The styrene-based thermoplastic elastomer is preferably contained in an amount of 1 to 20% by weight based on the total composition. When the content is less than 1% by weight, the impact property becomes weak. When the content is more than 20% by weight, heat resistance and mechanical properties are deteriorated .

In the present invention, a polyvinyl butyral resin is used as an additive for improving the external stress cracking resistance of the polyphenylene ether resin.

In general, polyvinyl butyral is a thermoplastic resin which is synthesized by the reaction of polyvinyl alcohol and butyl aldehyde, has excellent chemical resistance and is excellent in adhesion to glass, and is preferably a compound represented by the following formula (2).

The polyvinyl butyral resin preferably has a melt index of 1 to 20 g / 10 min (230 DEG C, 2.16 kg) based on ASTM D 1238. When the melt index is less than 1 g / 10 min, And the workability is deteriorated. When it exceeds 20 g / 10 min, there arises a problem that rigidity, stress uniformity, chemical resistance and elongation are deteriorated.

Commercially available products of the polyvinyl butyral used include, for example, BUTACITE from DuPont, or Shark pellet from Shark solutions, which can be used for finishing in safety glass or construction glass manufacturing operations It is also possible to use polyvinyl butyral recovered from car glass or architectural glass pieces, which can be used without limitation without departing from the purpose and scope of the present invention.

The polyvinyl butyral resin is preferably contained in an amount of 0.01 to 7.00 wt% based on the total weight of the composition. When the content is less than 0.01 wt%, the effect of improving the external stress cracking resistance is small. When the content is more than 7.00 wt% The compatibility with ether is deteriorated, peeling occurs in injection molding, mechanical strength is lowered, flame retardancy is reduced, and external stress cracking resistance tends to be rather reduced.

In order to impart flame retardancy to the resin composition, a flame retardant is mixed. In the present invention, an aromatic polyphosphate and a melamine polyphosphate are used as the flame retardant.

The halogen-containing flame retardant has excellent flame retardancy but causes environmental and health problems. The halogen-free flame retardant of the present invention has less toxicity and easy handling than the halogen flame retardant.

When heat is applied to melamine polyphosphate, melamine decomposes and melamine and phosphate condense, respectively, and flame retardancy is mainly due to mechanism of endothermic reaction and condensation process.

The polyphosphate of the flame retardant acts as a dehydrogenation catalyst to induce char formation and exhibits flame retardant properties, and does not generate toxic gas during thermal decomposition and generates less smoke than other flame retardants.

In addition, additives such as a heat stabilizer, an antioxidant, a dispersant, an inorganic additive, a light stabilizer, a pigment, and a dye may be added to the resin composition according to the production method of the resin.

Hereinafter, the present invention will be described in more detail with reference to the following examples, comparative examples and test examples.

It is to be understood, however, that the invention is not to be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Will be apparent to those skilled in the art to which the present invention pertains.

In addition, contents not described here can be inferred sufficiently technically by those having ordinary skill in the art, and a detailed description thereof will be omitted.

≪ Examples 1 to 5 and Comparative Examples 1 and 2 >

The flame retardant thermoplastic resin composition was prepared by the following composition and dried at 80 DEG C for 3 hours. The resin composition was injection-molded at an cylinder temperature of 250 to 290 DEG C and a mold temperature of 40 to 80 DEG C using an injection molding machine, .

Composition (% by weight) Example Comparative Example One 2 3 4 5 One 2 A ^{Note 1)} 62.04 61.64 60.84 59.24 57.64 56.04 54.44 B ^{Note 2)} 17.76 17.66 17.46 17.06 16.66 16.26 15.86 C ^{Note 3)} 4 4 4 4 4 4 4 D ^{Note 4)} 0.5 One 2 4 6 8 10 E E-1 ^{Note 5)} 5 5 5 5 5 5 5 E-2 ^{Note 6)} 10 10 10 10 10 10 10 F ^{Note 7)} 0.2 0.2 0.2 0.2 0.2 0.2 0.2 G ^{Note 8)} 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Note 1) Polyphenylene ether: poly (2,6-dimethylphenyl ether) (PX-100F, Mitsubishi, Japan), powder particles, average particle diameter (several tens of 탆)
Note 2) Rubber-modified polystyrene resin: Rubber-reinforced polystyrene resin (S834, Hyundai Electronics Co., Ltd., Korea)
OIL EXTENDED poly (styrene-butadiene) block copolymer, styrene content: 30%, oil content: 50%, styrene-based thermoplastic elastomer (PLASMER 5045N, Hyundai I &
10 g / 10 min under conditions of a melting point of 180 to 190 캜, a temperature of -30 캜 and a melt index of 230 캜 / 2.16 ㎏ (see, for example, Shark pellet, Shark solutions,
Note 5) Flame retardant: aromatic polyphosphate (PX-200, Daihachi, Japan)
Note 6) Flame retardant: melamine polyphosphate (OP-1312, Clariant, USA)
Note 7) Antioxidants: 1: 1 mixture of SONGNOX 1010 and SONGNOX 1680 from Songwon Industries (Korea)
Note 8) Dispersant: (E WAX, FLEXA, Germany)

<Test Example>

The tensile strength, elongation, flexural modulus, Izod impact strength, external stress cracking resistance and flame retardancy of the test pieces prepared in Examples 1 to 5 and Comparative Examples 1 and 2 were measured. Five specimens were measured and the upper and lower limits were excluded And the remaining average values are shown in Table 2 below.

Example Comparative Example One 2 3 4 5 One 2 Tensile strength ^{Note 1 )}
(Kgf / cm2) 690 686 669 650 610 590 570 Elongation (%) ^{Note 1)} 8 8.5 10 11 8.5 7 6 Flexural modulus ^{Note 2 )}
(Kgf / cm2) 23100 23010 22850 22460 22150 20156 19850 Izod impact strength ^{Note 3 )}
(Kgf · cm / cm) 12 14 15.9 17 12 10.1 7.5 ESCR (hours) ^{Note 4)} 0.5 0.7 One 1.4 1.2 0.6 0.1 Flammability (UL 94) ^{Note 5)} V0 V0 V0 V0 V0 V1 V1 Note 1) ASTM D 638, measuring speed 50 mm / min
Note 2) ASTM D790, specimen thickness 6.4 mm, measuring speed 10 mm / min
Note 3) ASTM D256, Specimen thickness 6.4 mm, Measured by notch using notch
Note 4) ASTM D638 TYPE 1 Tensile specimens are clamped with a metal jig (METAL ZIG) prepared in advance with 2% strain (STRAIN) and immersed in a standard reagent (TRI NORMAL BUTYL PHOSPHATE) Measure the time to
Note 5) Measured by the UL 94 test, a method prescribed by the Underwriter's Laboratory Inc. of the United States (test pieces held vertically are flamed for 10 seconds, The method is the length of time for which the test piece is continued to be flame-burned after the ignition source has been dropped away, and the ignition of the surface by the dripping is performed by dropping from the test piece ) Determined by being ignited by water)

In Table 2, flammability grades are classified according to the criteria shown in Table 3 below.

V0 V1 V2 Burning time (1st and 2nd respectively) Less than 10 seconds Less than 30 seconds Less than 30 seconds Secondary stream + Glowing Less than 30 seconds 60 seconds or less 60 seconds or less Total burning time Less than 50 seconds Less than 250 seconds Less than 250 seconds ignition of cotton by drip none none has exist

In Table 2, the external stress cracking resistance (ESCR) was confirmed by adding 0.5 to 10% by weight of polyvinyl butyral to the resin composition. In a comparative example in which polyvinyl butyral was added in an amount of 8% by weight or more, The mechanical properties and the ESCR characteristics are reduced due to the incompatibility of vinyl butyral, and particularly, the flame retardancy is lowered.

When the polyvinyl butyral resin is added to the polyphenylene ether resin mixed with the rubber-modified polystyrene resin and the styrenic thermoplastic elastomer as described above, the external stress cracking resistance is improved and the tensile strength, elongation, and elongation due to the addition of the polyvinyl butyral resin, The bending elastic mule and the Izod impact strength are improved and the flame retardancy is improved due to the addition of the aromatic polyphosphate and the flame retardant of melamine polyphosphate. Therefore, the parts for automobiles, electric / electronic devices, tanks, and containers requiring mechanical properties, ESCR characteristics and flame retardancy , Cables, and the like.

Claims (12)

20 to 70% by weight of polyphenylene ether;
10 to 40% by weight of a rubber-modified polystyrene resin composed of a copolymer of a styrene-based monomer and a monomer copolymerizable with a styrene-based monomer, or a styrene-based graft copolymer;
Polystyrene-polyisoprene diblock copolymer, polystyrene-polyisoprene diblock copolymer, poly alpha methyl styrene-polybutadiene diblock copolymer, polystyrene-polybutadiene-polystyrene triblock copolymer, polystyrene-polyisoprene-polystyrene triblock copolymer, - at least one styrenic thermoplastic resin selected from the group consisting of polyalpha methylstyrene triblock copolymers, poly alpha methylstyrene-polyisoprene-polyalpha methylstyrene triblock copolymers and hydrogenated block copolymers thereof, 1 to 20% by weight of a block copolymer of an elastomer;
0.01 to 7.00% by weight of a polyvinyl butyral resin; And
And 1 to 20% by weight of a flame retardant; and wherein the flame retardant thermoplastic resin composition has improved external stress cracking resistance. The method according to claim 1,
Wherein the polyphenylene ether is a compound represented by the following general formula (1), wherein the resistance to external stress cracking is improved.
[Chemical Formula 1]

(Wherein R ₁ to R ₄ each independently represent a hydrogen-substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a hydrogen-substituted or unsubstituted haloalkyl group having 1 to 30 carbon atoms, a hydrogen-substituted or unsubstituted carbon number 1 A substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a hydrogen-substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms, a hydrogen atom substituted or not substituted with hydrogen, a substituted or unsubstituted amino group having 1 to 30 carbon atoms, A substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms) The method according to claim 1,
The polyphenylene ether may be selected from the group consisting of poly (2,6-dimethyl-1,4-phenylene) ether, poly (2,6- 1,4-phenylene) ether, poly (2,6-dibutyl-1,4-phenylene) ether, poly (2-methyl-6-tolyl-1,4-phenylene) ether, poly Ether, poly (2-methyl-6-butyl-1,4-phenylene) ether, poly (2,6-diethoxy-1,4-phenylene) ether, poly (2,6-dimethoxy-1,4-phenylene) (2,6-dimethyl-1,4-phenylene) ether and poly (2,3,6-trimethyl-1,4-phenylene) And copolymers of poly (2,6-dimethyl-1,4-phenylene) ether and poly (2,3,5,6-tetramethyl-1,4-phenylene) ether It characterized in that the at least one, external stress cracking resistance is improved flame-retardant thermoplastic resin composition. The method according to claim 1,
Wherein the polyphenylene ether has an intrinsic viscosity of 0.1 to 0.9 dl / g in a chloroform solvent at 25 캜, wherein the polyphenylene ether has improved external stress cracking resistance. delete The method according to claim 1,
Wherein the styrenic monomer is at least one selected from the group consisting of styrene,? -Methylstyrene, and p-methylstyrene, wherein the external stress cracking resistance is improved. The method according to claim 1,
Wherein the monomer copolymerizable with the styrenic monomer is at least one monomer selected from the group consisting of acrylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, maleimide or N-phenylmaleimide , And an external stress cracking resistance is improved. The method according to claim 1,
The styrene-based graft copolymer may be a copolymer of an impact-resistant polystyrene resin, an acrylonitrile-butadiene-styrene resin, a resin obtained by substituting butadiene of an acrylonitrile-butadiene- styrene resin with an ethylene- Wherein the thermoplastic resin composition is at least one selected from the group consisting of a thermoplastic resin and a resin. delete The method according to claim 1,
Wherein the styrenic thermoplastic elastomer further comprises an oil. The flame retardant thermoplastic resin composition of claim 1, wherein the styrene-based thermoplastic elastomer further comprises an oil. The method according to claim 1,
Wherein the polyvinyl butyral resin has a melt index of 1 to 20 g / 10 minutes (230 DEG C, 2.16 kg) as measured according to ASTM D 1238. The flame retardant thermoplastic resin composition of claim 1, The method according to claim 1,
Wherein the flame retardant is a mixture of an aromatic polyphosphate and a melamine polyphosphate, wherein the flame retardant thermoplastic resin composition has improved external stress cracking resistance.