JP2002146037A - Method for producing flame-retardant thermoplastic resin blended product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a flame-retardant thermoplastic resin blended product having good flame retardancy without decreasing impact strength in spite of adding a flame retardant. SOLUTION: This method for producing a flame-retardant thermoplastic resin blended product having at least two resin phases and containing a flame retardant is characterized by comprising the 1st step of making a melt kneading of the flame retardant with a resin having relatively smaller oxygen index among the resins constituting the resin phases and the 2nd step of making a melt kneading of the composition obtained from the 1st step with resin (S) having relatively greater oxygen index.

Description

[Detailed description of the invention]

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a flame-retardant thermoplastic resin blend having good flame retardancy and good impact strength, and a flame-retardant thermoplastic resin blend obtained by the method. .

[0002]

BACKGROUND OF THE INVENTION Thermoplastic resins such as polycarbonate resins (PC), ABS resins (ABS), polystyrene resins (PS),
Polyphenylene ether resin (PPE), polybutylene terephthalate resin (PBT), polyethylene terephthalate resin (PET), polyamide resin (PA), polyarylene sulfide resin (PAS), polyetherimide resin
(PEI) and the like are widely used in electric/electronic parts, OA equipment parts, etc. due to their excellent heat resistance, mechanical properties, electrical properties, etc.

[0003] In addition, polymer blends utilizing these features, such as PC/ABS, PC/PS, PC/PBT, PPE/PBT, PPE/P
Blends such as A, PPE/PAS, and PPE/PBT/PC have been developed.

[0004] Flame retardancy is often required for the above applications, and in order to meet this requirement, halogen-based, phosphorus-based, nitrogen-based, silicon-based, etc. flame retardants are added to the above blends.

[0005]

In order to obtain sufficient flame retardancy, a large amount of flame retardant must be added. This often leads to deterioration of the resin. Therefore,
There is a desire for a blend of thermoplastic resins in which the addition of a flame retardant does not reduce impact strength and provides better flame retardant properties.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have found that in the preparation of a blend containing a flame retardant such as those described above, a flame retardant is added to a resin having a lower flame retardancy and then a resin having a higher flame retardancy The inventors have found that a method of melt-kneading with a high resin yields a blend with less decrease in impact strength or with better flame retardancy, and arrived at the present invention.

[0007] That is, the present invention has two or more resin phases,
In the method for producing a thermoplastic resin blend containing a flame retardant, a first step of melt-kneading a resin having a relatively small oxygen index among the resins constituting the resin phase and the flame retardant;
and a second step of melt-kneading the composition obtained in the first step and a resin having a relatively high oxygen index.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The flame retardant used in the present invention is not particularly limited, but halogen-based, phosphorus-based, silicon-based and organometallic salt-based flame retardants are preferred.

Preferred examples of halogen flame retardants are brominated flame retardants, such as brominated polycarbonates (including oligomeric and polymeric types), brominated epoxy resins, brominated phenoxy resins, brominated polystyrenes and brominated polyphenylene ethers. and so on.

[0010] A preferred example of the phosphorus-based flame retardant is a phosphate ester-based compound represented by (Chem. 1).

[Chemical 1] [wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrocarbon, preferably a substituted or unsubstituted aromatic hydrocarbon. Preferred examples of R ₁ , R ₂ , R ₃ and R ₄ are phenyl groups,
Cresyl group, xylenyl group (eg, 2,6-xylenyl group), trimethylphenyl group, ethylphenyl group, cumyl group, butylphenyl group and the like. X is a divalent group containing a carbon atom and optionally containing an oxygen atom and/or a nitrogen atom, preferably -O-Y1 _- O- (wherein Y1 is _a substituted or unsubstituted aromatic carbon a hydrogen group, preferably a 1,4-phenylene group, a 1,3-phenylene group, or the like) or -O-Y2 _- R5 _- Y3 _- O- ₍ where Y2 and Y
₃ is a substituted or unsubstituted aromatic group, preferably a phenylene group, etc.; R ₅ is a hydrocarbon group or a hydrocarbonoxy group;
Preferably, it is an aliphatic hydrocarbon group having 1 to 9 carbon atoms, such as a 2,2'-propylene group. m is 0 to 5
is an integer of Other preferred examples of X are nitrogen-containing compounds. In particular, a form in which a nitrogen atom is directly bonded to a phosphorus atom, such as a 1,4-piperazinedyl group having the structure of Chemical Formula 2, is preferred.

[Chemical 2]

Examples of preferred phosphoric ester compounds include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, bisphenol A tetraphenyl diphosphate, bisphenol A tetracresyl diphosphate, resorcinol tetrakis(2,6-dimethylphenyl) phosphate. , tetraxylyl piperazine diphosphoramide, and the like.

A preferred example of the silicon-based flame retardant is a crosslinked or non-crosslinked silicone polymer obtained by polymerizing at least one of the siloxane units represented by Chemical Formula 3.

[0013]

[Chemical 3] [Here, R5, _R6 , _R7 , _R8 , _R9 and R10 each independently represent a substituted or unsubstituted monovalent hydrocarbon group having ₁ to ₁₀ carbon atoms. ]

[0014] Alternatively, copolymers of the above silicone-based polymers with other polymers such as polycarbonate are also preferred.

Preferred examples of organic metal salt flame retardants include metal salts of aromatic sulfonic acid amides and metal salts of aromatic sulfonic acids. Preferred metals of the metal salt are alkali metals such as sodium or potassium, alkaline earth metals such as magnesium or calcium, copper or aluminum and the like.

The thermoplastic resin in the present invention is preferably polycarbonate resin, ABS resin, polystyrene resin, polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin, polyarylene sulfide resin, It is a polyetherimide resin.

Preferred examples of polycarbonate resins are
It is an aromatic polycarbonate polymerized by solution, melt or solid phase polymerization by a known phosgene method or melt method (see, for example, Japanese Patent Application Laid-Open Nos. 215763/1988 and 124934/1990). A polycarbonate-based resin consists of a carbonate component and a diphenol component. Precursors for introducing the carbonate component include, for example, phosgene and diphenyl carbonate. Suitable diphenols also include, for example, 2,2-bis(4-hydroxyphenyl)propane (so-called bisphenol A),
2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4
-hydroxyphenyl)propane, 1,1-bis(4-
hydroxyphenyl)cyclohexane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)decane, 1,4-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclododecane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclododecane; 4,4-dihydroxydiphenyl ether, 4,4-thiodiphenol, 4 ，
4-dihydroxy-3,3-dichlorodiphenyl ether, 4,4-dihydroxy-2,5-dihydroxydiphenyl ether and the like. These can be used alone or in combination. In addition, it is also possible to use a compound having 3 or more phenolic hydroxyl groups. A preferred polycarbonate resin is bisphenol A polycarbonate.

Preferred examples of ABS resins are (a) a rubbery polymer, (b) a vinyl cyanide monomer component and (c)
It is a copolymer containing an aromatic vinyl monomer component.

The rubbery polymer (a) includes polybutadiene, polyisoprene, random copolymers and block copolymers of styrene-butadiene, hydrogenated products of these block copolymers, and acrylonitrile-butadiene copolymers. , diene rubbers such as butadiene-isoprene copolymers, ethylene-propylene random copolymers and block copolymers, ethylene-butene random copolymers and block copolymers, copolymers of ethylene and α-olefins Copolymers, copolymers of ethylene-methacrylate, ethylene-butyl acrylate, etc., and ethylene-unsaturated carboxylic acid esters, copolymers of ethylene and fatty acid vinyls, such as ethylene-vinyl acetate, ethylene-propylene-ethylidene norbornene copolymers , ethylene-propylene non-conjugated diene terpolymers such as ethylene-propylene-hexadiene copolymers, butylene-isoprene copolymers, etc., and these may be used singly or in combination of two or more. A preferred rubbery polymer is ethylene-
Propylene rubbers, ethylene-propylene non-conjugated diene terpolymers and diene rubbers, particularly preferably polybutadiene and styrene-butadiene copolymers. Preferably.

The vinyl cyanide monomer component (b) includes, for example, acrylonitrile and methacrylonitrile, and one or more of them are used.

As the aromatic vinyl monomer component (c),
For example styrene, α-methylstyrene, o-, m- or p-methylstyrene, vinylxylene, monochlorostyrene, dichlorostyrene, monobromostyrene,
Dibromostyrene, fluorostyrene, p-tert-butylstyrene, ethylstyrene, vinylnaphthalene and the like can be mentioned, and one or two or more of them are used. Styrene and α-methylstyrene are preferred.

[0022] There are no particular restrictions on the production method of the ABS copolymer, and commonly known methods such as bulk polymerization, solution polymerization, bulk suspension polymerization, suspension polymerization and emulsion polymerization are used. again,
AB by blending separately copolymerized resins
It is also possible to obtain S copolymers. A preferred example of an ABS copolymer is an acrylonitrile-styrene-butadiene copolymer.

[0023] A preferred example of the polystyrene resin is represented by the general formula (Chem. 4).

[Chemical 4] [wherein R ₁₁ is a hydrogen atom or a C 1-4 alkyl group, Z is a halogen atom or a C 1-4
and p is an integer of 0 to 5]. Such polystyrene resins include, for example, homopolymers of styrene or derivatives thereof, and polybutadiene,
Polyisoprene, butyl rubber, EPDM, ethylene-propylene copolymer, natural rubber, styrenic polymers modified with natural or synthetic elastomeric materials such as epichlorohydrin, and styrene-containing copolymers, e.g. , styrene-acrylonitrile copolymer (SAN), styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Preferred styrenic polymers for this invention are homopolystyrene and rubber reinforced polystyrene.

Preferred examples of polyphenylene ether resins are represented by the general formula (Chemical Formula 5):

[Chemical 5] [wherein R _{12 ,} R ₁₃ , R ₁₄ and R ₁₅ are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a haloalkyl having at least two carbon atoms between the halogen atom and the phenyl ring; or a haloalkoxy group and containing no tertiary α-carbons, where n is an integer representing the degree of polymerization. ], and may be a single polymer represented by the above general formula or a copolymer in which two or more of them are combined. In preferred embodiments, R ₁₂ and R ₁₃ are alkyl groups having 1 to 4 carbon atoms, and R ₁₄ and R ₁₅ are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms. For example poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-
diethyl-1,4-phenylene) ether, poly(2-
methyl-6-ethyl-1,4-phenylene)ether,
Poly(2-methyl-6-propyl-1,4-phenylene) ether, poly(2,6-dipropyl-1,4-phenylene) ether, poly(2-ethyl-6-propyl-1,4-phenylene) ether and the like. As the PPE copolymer, the polyphenylene ether repeating unit may contain an alkyl trisubstituted phenol, such as
Copolymers containing a portion of 2,3,6-trimethylphenol may be mentioned. A copolymer obtained by grafting a styrenic compound to these PPEs may also be used. Examples of styrene-based compound-grafted polyphenylene ethers include the above PPE and styrene-based compounds such as styrene, α-methylstyrene, vinyltoluene,
Examples thereof include copolymers obtained by graft polymerization of chlorostyrene and the like.

A preferred example of the polybutylene terephthalate resin is a polymer obtained by condensation reaction of terephthalic acid or its ester-forming derivative as the acid component and 1,4-butanediol or its ester-forming derivative as the diol component. . As the dicarboxylic acid component, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,
Dicarboxylic acids other than terephthalic acid, such as 4-cyclohexanedicarboxylic acid or ester-forming derivatives thereof, may also be used. As diol components, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, poly Diols other than 1,4-butanediol, such as tetramethylene glycol, polyethylene glycol, and polypropylene glycol, may also be used.

Polyethylene terephthalate resin means a polymer obtained by condensation reaction of terephthalic acid or its ester-forming derivative as an acid component and ethylene glycol or its ester-forming derivative as a diol component. As the dicarboxylic acid component, dicarboxylic acids other than terephthalic acid such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and ester-forming derivatives thereof are used. You can use it. Further, as diol copolymer components, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, methanol, neopentyl glycol, polytetramethylene glycol,
Diols other than ethylene glycol, such as polyethylene glycol and polypropylene glycol, may also be used.

[0027] A preferred example of the polyamide-based resin is a polymer that has a --CO--NH-- bond in the polymer main chain and can be melted by heating. For example, nylon-4, nylon-6,
Nylon-12, Nylon-6,6, Nylon-4,
6, nylon-6,10, nylon-6,12 and nylon-6,T (polyamide composed of hexamethylenediamine and terephthalic acid), nylon-MXD,6 (polyamide composed of metaxylenediamine and adipic acid), hexamethylene Copolymers of diamines, adipic acid and caprolactam, mixtures thereof, and the like.

Polyarylene sulfide resin (PA
A preferred example of S) means a polymer containing a structural unit represented by (Chem. 6) in the polymer main chain.

[Chemical 6] [Here, R ₁₆ is a hydrocarbon having 1 to 10 carbon atoms, m
is an integer of 0 to 4]. A preferred PAS is polyphenylene sulfide.

[0029] The resins in the blends of this invention are two or more and have at least two resin phases. Having at least two resin phases means that two or more resins contained in the blend are not molecularly compatible and form a single phase, but form multiple resin phases, a so-called phase separation structure. means to take The structure of each phase is not particularly limited, but in the case of a blend of two kinds of resins, it is generally preferable to have a continuous phase/dispersed phase (so-called sea-island structure), layered structure, or mutually continuous phase structure. The size of each phase is not particularly limited, but in the case of a continuous layer/dispersed layer structure, the average particle size of the dispersed layer is preferably 100 μm or less.
More preferably 50 μm or less, most preferably 10 μm
It is below. If the size of the dispersed phase is too large, sufficient mechanical properties cannot be obtained.

Examples of preferred resin blend combinations are:
PC/ABS, PC/PS, PC/PBT, PC/P
A, PPE/PBT, PPE/PA, PPE/PAS,
PC/PS/PPE, PC/PBT/PPE, and the like.
These combinations are immiscible or semi-miscible combinations. With or without the addition of a compatibilizer, fine dispersion of the resins, the so-called micro-phase separation structure, can be achieved. However, it does not form a single phase.

[0031] The oxygen index can be measured according to ASTM D-2863.
For example, it is described in "Polymer Degradation/Collapsing Troubleshooting and Latest Modification/Stabilization Technology Comprehensive Data Collection", pp. 347-348, High Polymer Property Study Group, 1981. Representative values for these polymers are shown in Table 1.

[0032]

[Table 1]

The method of the present invention comprises a first step and a second step. In the first step, among the resins constituting the resin phase in the thermoplastic resin blend, a resin having a relatively low oxygen index and a flame retardant are combined. Melt and knead. The resin melt-mixed in the first step is the resin with the smaller oxygen index in the case of a binary blend. For example, in the case of PC/PS, PS, PC/PB
In the case of T, it is PBT. In this case, a part of the resin having a small oxygen index may be melt-kneaded, or the entire resin may be melt-kneaded. In the case of a ternary blend, resins other than the resin with the highest oxygen index are melt-kneaded in the first step. For example, in the case of PC/ABS/SAN, the ABS graft copolymer and/or SAN are melt-kneaded in the first step, and in the case of PC/PBT/PPE, PBT and/or PC are melt-kneaded in the first step.
In the case of PC/PBT/PPE, part or all of PBT, part or all of PC, or part or all of PC and PBT may be melt-kneaded in the first step. The amount of the flame retardant mixed in the melt kneading in the first step is preferably 1 to 50 parts by weight per 100 parts by weight of the resin having a relatively small oxygen index. If it exceeds 50 parts by weight, the kneading in the first step may not be efficient. In the second step, the composition (masterbatch) obtained in the first step is melt-kneaded with a resin having a relatively large oxygen index to obtain a flame-retardant thermoplastic resin blend. In the second step, additional flame retardants may or may not be added as desired. If added, the additional flame retardant may be the same as or different from that used in the first step, and the amount added will depend on the efficiency of the kneading process and the flame retardancy and final physical properties of the composition. selected accordingly

[0034] The first step is preferable, and after mixing predetermined amounts of the components with a super mixer, Henschel mixer, ribbon blender, super floater, etc., the mixture is melt-kneaded with a device such as an extruder, kneader, Banbury mixer, heating rollers, or the like. It can be done by A preferred method is melt-kneading with an extruder.

[0035] The second step is preferably performed by mixing predetermined amounts of the components with a super mixer, Henschel mixer, ribbon blender, super floater, etc., and then using a device such as an extruder, kneader, Banbury mixer, heated rollers, or the like. can. A preferred method is melt-kneading with an extruder.

The first step and the second step are preferably carried out continuously using an extruder having feed ports at two or more positions. The components to be melt-kneaded in the first step are supplied from the upstream supply port of the extruder, the first step is performed in the upstream part, and the components to be melt-kneaded in the second step are supplied from the downstream supply port. Then, the second step can be performed downstream.

Another preferred example is a method in which the first step and the second step are carried out separately. For example, the first step is performed using an extruder to pelletize, the pellets and the remaining constituents are melt-kneaded using the same or a different extruder,
A second step can be performed.

In the method of the present invention, various additives can be added, if necessary, in addition to the thermoplastic resin and flame retardant. Additives include, for example, anti-drip agents, reinforcing agents (talc, mica, clay, glass fiber, glass flakes, milled ballast, carbon fiber, etc.), pigments, dyes, fillers (carbon black, silica, titanium oxide, etc.), Stabilizers, heat-resistant agents, antioxidants, weather-resistant agents, plasticizers, antistatic agents, and fluidity improvers. These additives are
It can be added in either the first step, the second step, or both.

[0039] The anti-dripping agent is an additive that functions to suppress dripping during combustion, and known ones can be used. In particular, polytetrafluoroethylene (PTFE) or the like, which forms a fibril structure in a polycarbonate-based resin, is highly effective in suppressing dripping, and thus is suitable.

Among these polytetrafluoroethylenes (PTFE), those having excellent dispersibility, for example, PTFE emulsified and dispersed in a solution such as water, polycarbonates and styrene-acrylonitrile copolymers are typified. A resin-encapsulated PTFE is preferable because it gives a molded body made of a polycarbonate composition a good surface appearance.

[0041] In the case of emulsifying and dispersing PTFE in a solution such as water, there is no particular limitation, but PTFE having an average particle size of 1 micron or less is preferred, and 0.5 micron or less is particularly preferred.

Specific examples of commercially available PTFE include Teflon 30J (trademark, Mitsui DuPont Fluorochemicals Co., Ltd.) and Polyflon D-2.
C (trademark, Daikin Chemical Industries, Ltd.), Aflon AD
1 (trademark, Asahi Glass Co., Ltd.).

[0043]

EXAMPLES The present invention will now be described with reference to examples. Materials used in Examples and Comparative Examples are as follows. 1. Polycarbonate resin: bisphenol A polycarbonate LEXAN (manufactured by Nippon GE Plastics), MI value measured at 300° C., 1.2 kg: 12.
3 g/10 minutes2. Styrene-based resin: ABS resin: SANTAC AT-07 (Japan A&L Co., Ltd.)
product), rubber content = 20%, MI = 2.5 g/min (20
0° C., 5 kg) HIPS resin: 870ST (Japan Polystyrene Co., Ltd.)
), polybutadiene grafted with styrene.
Rubber content = 9.5%, MI = 1.9 g/min (200
°C, 5 kg)3. Flame retardant: bisphenol A-tetraphenyl diphosphate CR741S4. Polytetrafluoroethylene: D2-C (manufactured by Daikin Industries, Ltd.)

The physical properties of the thermoplastic resin blends obtained in Examples and Comparative Examples were measured as follows. The test piece was prepared by Toyo Machinery & Metal Co., Ltd.
A 0t injection molding machine was used at a barrel temperature of 260°C and a mold temperature of 50°C. (1) Izod impact resistance: 63.5×12.7×3.
It was measured according to ASTM D-265 using a 2 mm test piece. (2) Tensile strength and elongation: ASTM D-638
(tensile speed: 10 mm/min). (3) Flexural strength and modulus of elasticity: 127 x 12.7 x
It was measured according to ASTM (D790) using a 6.4 mm test piece. (4) Deflection temperature under load: 127 x 12.7 x 6.4 mm
was measured according to ASTM D-648 (load 18.6 kg, temperature increase rate 2° C./min) using a test piece. (5) Flame retardancy (UL94): Five test pieces (125x13x1.6
mm).

Example 1 Using a twin-screw extruder TEX44αII manufactured by The Japan Steel Works, Ltd., the following first and second steps were carried out. First, as the first step, A as a styrene resin
20 parts by weight of BS resin and 6.67 parts by weight of flame retardant were melt-kneaded to prepare a masterbatch having a weight ratio of 75:25. Extrusion conditions are 200 rpm rotation speed and 23 barrel temperature.
It was 0°C. Next, in the second step, 80 parts by weight of polycarbonate resin, 26.67 parts by weight of the masterbatch obtained in the first step, 8.33 parts by weight of the same flame retardant as used in the first step, and an anti-drip agent Melt-knead 0.6 parts by weight of polytetrafluoroethylene as
A thermoplastic blend was prepared. Extrusion conditions are rotation speed of 350 rpm, output of 150 kg, and barrel temperature of 250-2.
It was 60°C. Table 2 shows the measurement results of the physical properties of the obtained thermoplastic resin blend.

Comparative Example 1 The same amount of material used in Example 1 was melted and kneaded at once without being divided into two steps to produce a thermoplastic resin blend, and its physical properties were measured. Melt-kneading was performed using the same extruder as used in Example 1, and the extrusion conditions were the same as in the second step in Example 1. Table 2 shows the results.

Example 2 and Comparative Example 2 Thermoplastic resin blends were produced in the same manner as in Example 1 and Comparative Example 1, respectively, except that the number of revolutions was 200 rpm in the extrusion conditions of the second step. Physical properties were measured. Table 2 shows the results.

Example 3 A thermoplastic resin blend was produced in the same manner as in Example 1, except that the amount of the flame retardant added in the second step was changed to 4.33 parts by weight, and its physical properties were measured. Table 2 shows the results.

Comparative Example 3 A thermoplastic resin blend was produced in the same manner as in Comparative Example 1, except that the amount of flame retardant was changed to 11 parts by weight, and its physical properties were measured. Table 2 shows the results.

Example 4 A thermoplastic resin blend was produced in the same manner as in Example 1 except that HIPS resin was used as the styrene resin and the amount of the flame retardant added in the second step was changed to 5.33 parts by weight. and measured its physical properties. Table 2 shows the results.

Comparative Example 4 A thermoplastic resin blend was produced in the same manner as in Comparative Example 1 except that HIPS resin was used as the styrene resin and the amount of the flame retardant was changed to 12 parts by weight, and its physical properties were measured. .
Table 2 shows the results.

[0052]

[Table 2]

As is apparent from Table 2, the method of the present invention can produce flame-retardant thermoplastic resin blends with excellent flame retardancy and good impact resistance ( Examples 1 and 2). Also, even with a small amount of flame retardant, high flame retardancy can be obtained (Examples 3 and 4).

[0054]

According to the method of the present invention, a thermoplastic resin blend having good flame retardant properties can be produced without lowering the impact strength even with the addition of a flame retardant.

──────────────────────────────────────────────────── ──── continuation of the front page F term (reference) 4F070 AA06 AA07 AA08 AA18 AA47 AA50 AA52 AA54 AA55 AA58 AC50 AC55 AC76 AC84 AC87 AC88 AC92 AE07 FA17 FB07 4J002 BC00W BC00X BC00Y BC05W BC05X BC05Y BC06W BC06X BC06Y BC07W BC07X BC07Y BC11Z BP01W BP01X CD12Z CF06W CF06X CF07W CF07X CF07Y CG00W CG00X CG00Y CG01W CG01X CG01Y CG03W CG03X CG03Y CG03Z CH07W CH07X CH07Y CH07Z CH08Z CL00W CL00X CL01W CL01X CL03W CL03X CM04W CM04X CN01W CN01X CP03Z EV236 EV286 EW046 FD13Z FD136

Claims (7)

[Claims] 1. In a method for producing a thermoplastic resin blend having two or more resin phases and containing a flame retardant, a resin having a relatively low oxygen index among the resins constituting the resin phase and the flame retardant. and a second step of melt-kneading the composition obtained in the first step and a resin having a relatively large oxygen index. A flame-retardant thermoplastic resin blend characterized by comprising manufacturing method. 2. The method according to claim 1, wherein the amount of the flame retardant in the melt kneading of the first step is 1 to 50 parts by weight with respect to 100 parts by weight of the resin having a relatively low oxygen index. Production method. 3. The flame retardant is one or more flame retardants selected from the group consisting of phosphate ester flame retardants, halogen flame retardants, nitrogen-containing flame retardants, silicon-containing flame retardants and organic metal salts. The manufacturing method according to any one of claims 1 to 2. [Claim 4] The resin is polycarbonate resin, ABS
resin selected from the group consisting of polystyrene resins, polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyamide resins, polyarylene sulfide resins, and polyetherimide resins. The manufacturing method according to any one of claims 1 to 3, wherein 5. The method is characterized in that the first step and the second step are carried out continuously in one extruder, and the first step is carried out in the upstream part of the extruder and the second step is carried out in the downstream part of the extruder. The production method according to any one of claims 1 to 4 6. A method according to any one of claims 1 to 4, characterized in that the first step and the second step are carried out separately. 7. A flame retardant resin blend produced by the method of any one of claims 1-6.