JPH09221574A - Flame-retardant resin composition containing polystyrene obtained by anionic polymerization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flame-retardant styrene resin composition excellent in a balance between flowability and impact resistance by mixing a rubber-modified vinylaromatic polymer in which the continuous phase comprises a resin containing a vinylaromatic polymer obtained by anionic polymerization with a flame retardant. SOLUTION: This composition comprises 99-50 pts.wt. rubber-modified vinylaromatic polymer (A) which is obtained by radical polymerization and in which the continuous phase comprises a resin containing a linear or branched vinylaromatic polymer obtained by anionic polymerization and 1-50 pts.wt. halogenated flame retardant or a mixture thereof with an antimony oxide or phosphorus flame retardant. The linear vinylaromatic polymer of component A should have a ratio of the weight-average molecular weight to the number- average ratio of 2.0 or below when determined by the gel permeation chromatography differential refractometry and have a weight-average molecular weight of 50,000-200,000. Also the branched vinylaromatic polymer of component A has restrictions on its molecular structure.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a styrene-based flame-retardant resin composition having an excellent balance of fluidity and impact resistance,
Various molded products requiring flame retardancy, such as home appliances and O
A A styrene-based flame-retardant resin composition that can be used as a molding material for machines, automobile parts, and the like.

[0002]

2. Description of the Related Art Styrenic resins are widely used industrially as inexpensive molding materials having excellent processability and various physical properties. In particular, there is a strong demand for flame retardancy in the use of molding materials in the field of weak electrical equipment, and many flame retardant technologies for styrene resins have been filed. For example, a combination of a halogen-based flame retardant and antimony oxide (JP-A-1-182342),
A method in which decabromodiphenyl ether is used as a flame retardant (Japanese Patent Publication No. 52-32898), and a method in which a halogenated diphenyl ether and a halogenated bisphenol type polycarbonate oligomer are used in combination in a specific amount of antimony trioxide (Japanese Patent Laid-Open No. 58-65741). Etc.

However, when the polystyrene resin is made flame-retardant by these methods, the physical properties are lowered, particularly the impact resistance strength is remarkably lowered, and depending on the flame retardant used,
Since the fluidity is extremely deteriorated, a flame-retardant resin composition having a good balance between impact resistance and fluidity has been desired.
In addition, in recent years, there has been an increasing demand for home appliances to be large and thin, and in order to meet these demands, it is required to improve the mechanical strength and high fluidity of the resin. The method of adding a plasticizer such as mineral oil, which is generally used to achieve high fluidity of the resin, reduces the flame retardancy and at the same time facilitates melt dripping during combustion.

For example, a wide type large television (28, 32,
High flow (MFR 30g / 10min or more) required for a housing material that can be injection molded at a low pressure of 36 inches)
UL94V-0 standard flame-retardant molding material using ordinary high-impact polystyrene, high-fluidity polystyrene, brominated epoxy resin as flame retardant, paraffin-based mineral oil as fluidity improver, etc. Then, in order to satisfy the required fluidity, it is necessary to add 4 to 6 parts by weight or more of mineral oil to 100 parts by weight of the resin part. Addition of a large amount of mineral oil naturally leads to a large decrease in heat resistance, resulting in a decrease in the mechanical strength of the resin.

UL94 vertic for flame retardancy
In the alburning test, this material is very difficult to achieve the V-0 flame retardant performance because the material is dripped during combustion.
Therefore, there is a limit to the method for improving the fluidity of the resin by adding the plasticizer such as mineral oil. In addition, a method of lowering the molecular weight of the resin matrix is used for the purpose of increasing the fluidity of the resin, but this method leads to a decrease in the mechanical strength of the resin, and therefore balances the mechanical strength and fluidity of the resin composition. This method is also not practical because it becomes very difficult to take and the resin becomes more brittle when made flame-retardant.

[0006]

An object of the present invention is to develop a styrene resin having high fluidity and high impact resistance, and yet maintain high fluidity and impact strength after flame retardation. To provide a flame-retardant resin composition.

[0007]

Means for Solving the Problems The present inventors have found that when a rubber-modified vinyl aromatic polymer (hereinafter abbreviated as HIPS) contains a certain amount or more of polystyrene obtained by an anionic polymerization method in a part of its matrix. , Has found that it has extremely high fluidity and high impact resistance.
It has been found that, when IPS is made flame-retardant, its high fluidity and high impact resistance that it had before the flame-retardation is maintained at a high level, and the present invention has been completed.

The present invention will be described in more detail below. The rubber-modified vinyl aromatic polymer in which the continuous phase is composed of a resin containing a vinyl aromatic polymer obtained by the anionic polymerization method which is the component (A) used in the present invention is a continuous phase of styrene or O. -Polymerizing a single or two or more vinyl aromatic monomers such as nuclear alkyl-substituted styrenes such as methylstyrene, α-alkyl-substituted styrenes such as α-methylstyrene, and nuclear halogen-substituted styrenes such as monochlorostyrene. A rubber in which the polymer obtained as a result constitutes a resin continuous phase, and the polymer component obtained by an anionic polymerization method is contained in the polymer, and the rubber-like polymer is dispersed in the form of particles as a dispersed phase. Reinforcing styrene polymer.

The vinyl aromatic polymer obtained by the anionic polymerization method used in the present invention is a polymer obtained by polymerizing the above-mentioned styrene type monomers with an anionic polymerization catalyst such as alkyllithiums. In anionic polymerization, a polymerization initiation reaction is fast, and a monodisperse polymer having a uniform chain length can be easily obtained. Usually, it is in a living state in which active metal lithium is bound to the polymer end, and by utilizing this active end to react with a polyfunctional low molecular weight compound, it is possible to form a star polymer having a branched structure. In the present invention, a linear structure polymer and a star structure polymer obtained from these vinyl aromatic monomers prepared by anionic polymerization are used.

The term "branched vinyl aromatic polymer component" as used in the present invention means a branched vinyl aromatic polymer having a structure represented by the following formula. M- (P) _n (In the formula, M is a branched nucleus of a polyfunctional compound residue or a polyvinyl aromatic compound residue, P is a vinyl aromatic polymer, and n is 3
The number of arms of the branched polystyrene of the present invention is in the range of 3 to 8, and preferably 3 to 8. 6 pieces, more preferably 3 to
There are four.

The content of the vinyl aromatic polymer obtained by the anionic polymerization method in the vinyl aromatic polymer forming a continuous phase is 5% by weight or more, preferably 10% by weight or more,
More preferably, it is 20% by weight or more.

The vinyl aromatic polymer obtained by the anionic polymerization method contained in the continuous phase of the rubber-modified vinyl aromatic polymer of the present invention has a linear structure.
And those having the branched radial structure described above. In particular, the greatest feature of the linear structure is that the molecular weight distribution is narrow. The vinyl aromatic polymer obtained by the anionic polymerization method is different from the ordinary radical polymerization method, and a polymer close to monodisperse is easily obtained. Therefore, there are no components such as extremely low molecular weight components or oligomers that adversely affect the physical properties. Therefore, when blending with HIPS of radical polymerization to introduce a polymer component by anionic polymerization into the resin continuous phase, these components are It is possible to reduce the molecular weight of the entire resin continuous phase without increasing the number.

Further, the composition of the present invention is a flame-retardant resin composition, and as described above, HIPS containing extremely small amount of low molecular weight components and oligomer components is hard to be dropped in the combustion test when it is flame retarded. The effect is recognized from.

The HIPS containing the vinyl aromatic polymer obtained by the anionic polymerization method of the present invention in the continuous phase may be prepared by any method. For example, normal HI
A method of blending PS with a monodisperse linear aromatic vinyl polymer synthesized by an anionic polymerization method. Further, a method of blending a branched or radial type vinyl aromatic polymer synthesized by a coupling method of anionic polymerization and the like can be mentioned.

The vinyl aromatic polymer having a linear structure obtained by anionic polymerization used in the present invention is a gel permeation chromatography differential refractive index method (PG
The ratio of the weight average molecular weight to the number average molecular weight (also referred to as C-RI method) (molecular weight distribution Mw / Mn) is 2.0 or less, and the weight average molecular weight is in the range of 50,000 to 20,000. Are in. If the molecular weight distribution (Mw / Mn) exceeds 2.0, the monodispersity characteristic of anionic polymerization tends to be lost, and if the weight average molecular weight is less than 50,000, the mechanical strength of the resin is insufficient. Tend to do 2
If it exceeds 0,000, the fluidity, which is a feature of the present invention, tends to be lost.

The branched vinyl aromatic polymer of the anion polymerization of the present invention has a weight average molecular weight MwL by GPC-light scattering method in the analysis by gel permeation chromatography (hereinafter abbreviated as GPC) of the continuous phase of the HIPS resin described later. Apparent weight average molecular weight Mw by GPC-RI method
It is necessary that the ratio of R is 1.10 or more, preferably 1.2 or more. As the number of branches of the branched vinyl aromatic polymer increases, the MwL / MwR value increases even if the content of the branched polymer is the same, but in the present invention, the number of branches is at most 8 branches. To MwL / MwR is 5
It is preferably 4 or less. H of the component (A) of the present invention
The weight average molecular weight of the continuous phase of IPS based on the GPC light scattering method is preferably in the range of 120,000 to 500,000, more preferably 150,000 to 300,000, and further preferably 150,000 to 2
It is in the range of 50,000.

When the branched vinyl aromatic polymer of the component (A) of the present invention is synthesized by the anionic polymerization coupling method,
Usually, it is a mixture of uncoupled products, dimers, trimers and even multimers. For this reason, even if a polymer having a uniform molecular weight distribution of 1.5 or less is used as the polymer before coupling, the molecular weight distribution tends to widen after the coupling reaction. Therefore, the molecular weight distribution of the branched vinyl aromatic polymer of the present invention may be in the range of 1.0 to 3.0. In the case of a branched vinyl aromatic polymer, the molecular weight distribution is broadened by the coupling reaction, but if the molecular weight distribution of the polymer before coupling is 1.5 or less, low molecular weight components and oligomer components that adversely affect the physical properties do not increase. Therefore, the molecular weight distribution may be broad to some extent.

The rubbery polymer forming the dispersed phase of the component (A) of the present invention is one having a glass transition temperature of -30 ° C or lower. Specific examples include polybutadiene, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR) and other diene polymers, ethylene-propylene-diene rubber (EPDM), acrylic rubber and the like. As the polybutadiene rubber, both high cis polybutadiene rubber and low cis polybutadiene rubber can be preferably used. Further, the above polybutadiene rubber, SBR, and NBR are unsaturated 2
A hydrogenated part or all of the heavy bonds can also be used.

The HIPS forming a part of the component (A) is generally prepared by mixing the vinyl aromatic monomer in the presence of the rubber-like polymer in a lump, lump / suspension, or emulsion polymerization condition. It can be obtained by radical polymerization, but the method of bulk polymerization is economically superior. In the case of bulk polymerization, a small amount of an inert solvent such as ethylbenzene or toluene may be added. By polymerizing the vinyl aromatic monomer in the presence of the rubbery polymer by each of the above methods, a part of the vinyl aromatic monomer is grafted around the rubbery polymer particles, and A dispersed phase having a structure in which some vinyl aromatic polymer particles are contained inside the polymer particles is formed.

The dispersed phase can be separated and collected by dissolving it in a good solvent of the vinyl aromatic polymer constituting the continuous phase of the rubber-modified vinyl aromatic resin composition, for example, methyl ethyl ketone, and centrifuging. Further, the average particle size of the dispersed phase formed by the rubber-like polymer as the component (A) is adjusted to a range of 0.1 to 4.0 μm according to a standard method. A more preferable range of particle diameter is 0.4 to 3.0 μm. The swelling index (Swelling Index) for toluene, which is a measure of the degree of crosslinking of the dispersed phase particles, is adjusted to a range of 6 to 14.

The branched vinyl aromatic polymer contained in the continuous phase of the component (A) of the present invention by the anionic polymerization method can be efficiently prepared, for example, by the anionic polymerization coupling method. Specifically, it is obtained by polymerizing the vinyl aromatic monomer in a hydrocarbon solvent using an organolithium compound, and subjecting the resulting active one-terminal vinyl aromatic polymer to a coupling reaction with a polyfunctional compound. Can be done. The organolithium compound of the above method is n-
Examples thereof include propyllithium, iso-propyllithium, n-butyllithium, iso-butyllithium, sec-butyllithium, tert-butyllithium and phenyllithium.

The polyfunctional compound used in the coupling reaction is a low molecular weight compound having 3 to 8 functional groups capable of reacting with an active lithium terminal to form a bond. Examples of these low molecular weight compounds include polyhalogen compounds, polyepoxy compounds, polycarboxylic acid ester compounds, polyketone compounds, polycarboxylic acid anhydrides and the like. Specifically, silicon tetrachloride, di (trichlorosilylyl) ethane, 1,3,5-tribromobenzene, methyltrichlorotin, epoxidized soybean oil,
Tetraglycidyl 1,3-bisaminomethylcyclohexane, dimethyl oxalate, tri-2-ethylhexyl trimellitate, tetramethyl pyromelliticate, 2,3-
Examples include diacetonitrile cyclohexanone and pyromellitic dianhydride.

When carrying out the anionic polymerization, 0.01 to 1.0 part by weight of the lithium compound is added to 100 parts by weight of the vinyl aromatic monomer. Further, the above polyfunctional compound is added in an amount of 0.5 to 1.5 times equivalent to the amount of organolithium and reacted. The reaction proceeds rapidly and is usually completed in a few minutes to a few tens of minutes. As the reaction solvent, cyclohexane, n-hexane, benzene, toluene, ethylbenzene, THF and the like are used. The reaction temperature for carrying out the anionic polymerization is -30 to 120 ° C. The polymerization time is usually several seconds to several hours, depending on the solvent used and the polymerization temperature.

Separately from the above coupling reaction, a vinyl aromatic monomer is polymerized in a hydrocarbon solvent using an organolithium compound as an initiator, and after completion of the polymerization, one-end active vinyl aromatic monomer existing in a living state. A multi-branched vinyl aromatic polymer can be synthesized by adding a small amount of a polyfunctional vinyl aromatic monomer (for example, divinylbenzene) as a polymerization initiator and polymerizing the polymer. In this method, the proportion of the polyfunctional monomer added is in the range of 0.1 to 1.0 with respect to the organolithium in molar ratio. According to this method, a branched polymer having a slightly broad molecular weight distribution and substantially branched, which is close to a star polymer, can be obtained.

Next, a method for analyzing the branched vinyl aromatic polymer used in the present invention will be described. In the measurement of the molecular weight of a general styrene resin, the styrene resin is separated by the molecular size by gel permeation chromatography, and the concentration of the styrene resin is detected by using a concentration detector such as a differential refractive index detector. It is the molecular weight calculated based on the calibration curve of the relationship between the elution time and the molecular weight prepared using the monodisperse polystyrene produced by.
However, since a branched polymer tends to be rolled up in a GPC solvent and flows out slowly, the molecular weight measured by the above GPC differential refractive index detector gives a measured value smaller than the actual molecular weight.

G was used for the analysis of the branched polystyrene of the present invention.
It is performed by using both the PC-light scattering method and the GPC differential refractive index method. The GPC-light scattering method measures the fluctuation due to the scattered light of the light based on the solute in the solution when the solution is exposed to the light. This fluctuation is caused by the thermal motion of the solute molecule, and the larger the solute molecule is, the larger the fluctuation becomes. The principle of molecular weight measurement by the light scattering method (GPCLALLS method) is to measure the size of molecules by observing the degree of this fluctuation in a dilute solution. In the GPC-light scattering method, if the molecular weight is the same regardless of the molecular size, the same molecular weight is given even if the elution position is different.

The prepolymer polymerized with butyllithium by anionic polymerization and the coupling agent are added to the prepolymer to measure the MwL of the polymer obtained by the coupling reaction by the GPC-light scattering method. Desired. Preparation of samples in which the blend ratio of branched polymer and linear polymer was changed using branched polymer of known degree of branching and molecular weight and linear monodisperse polymer of anionic polymerization or linear polydisperse polymer of radical polymerization which is considered to have almost no branching. Then, MwL by the GPC-light scattering method and MwR by the GPC-RI method are measured. MwL / MwR has a larger value as the number of branching components in the polymer increases, and thus serves as an index indicating the amount of branching polymer components in the sample.

% Of branched polymer and M in blend
A calibration curve can be created based on the value of wL / MwR. It is possible to know the concentration of the branched polymer in the unknown sample using this calibration curve. As an analysis method from the flame-retardant resin composition, the sample is dissolved using a good solvent for the polymer such as MEK, and the gel in the composition, insoluble matter such as inorganic substances such as antimony trioxide are removed by centrifugation, The branched component can be quantified by separating the flame retardant and the polymer by using a solvent such as alcohol for the soluble component and performing the GPC analysis on the polymer.

The flame retardant used as the component (B) of the present invention refers to a halogen flame retardant and / or a phosphorus flame retardant, and optionally contains antimony oxide. Examples of the halogen-based flame retardant used in the present invention include halogenated bisphenols, aromatic halogen compounds, halogenated polycarbonates, halogenated aromatic vinyl polymers, halogenated cyanurate resins and halogenated polyphenylene ether resins.

Preferably, decabrom diphenyl oxide, an oligomer of tetrabromobisphenol A, a brominated bisphenol phenoxy resin, a brominated bisphenol polycarbonate, a brominated polystyrene,
Examples of the halogenated bisphenols include brominated cross-linked polystyrene, and specific examples of the halogenated bisphenols are dibromobisphenol A, tetrabromobisphenol A, dichlorobisphenol A, tetrachlorobisphenol A, dibromobisphenol F, tetrabromobisphenol F,
Dichlorobisphenol F, tetrachlorobisphenol F, dibromobisphenol S, tetrabromobisphenol S, dichlorobisphenol S, tetrachlorobisphenol S and the like can be mentioned.

The organic phosphorus compound used in the present invention is, for example, phosphine, phosphine oxide, biphosphine, phosphonium salt, phosphinic acid salt, phosphoric acid ester, phosphorous acid ester and the like. More specifically, triphenyl phosphate, methyl neopentyl phosphate, pentaerythritol diethyl diphosphite, methyl neopentyl phosphite, phenyl neopentyl phosphite, pentaerythritol diphenyl diphosphate, dicyclopentyl hypophosphate, dineo. They are pentyl hypophosphite, phenylpyrocatechol phosphite, ethylpyrocatechol phosphite, and dipyrocatechol hypophosphite.

As the organic phosphorus compound, aromatic monophosphoric acid ester and aromatic condensed phosphoric acid ester are particularly preferable. Among the phosphoric acid esters, triphenyl phosphate, tricresyl phosphate or the like is preferable as the aromatic monophosphate ester, and the combined use of the aromatic monophosphate ester and the aromatic condensed phosphate ester is volatile resistance, It is preferable from the viewpoint of the balance of impact resistance, heat resistance and fluidity.

Antimony oxide, which is optionally used as the component (B) of the present invention, is used when a halogen-based flame retardant is used as the component (B). Antimony oxide effectively acts as a flame retardant aid when a halogen-containing compound is used as the flame retardant. Antimony oxides include antimony trioxide, antimony tetroxide and antimony pentoxide. Antimony oxide is 5 against halogen flame retardant
５０50% by weight is added.

In the present invention, the flame retardant performance or flame resistant performance of the flame retardant resin composition is not particularly specified. The effect of the present invention is that by containing a specific amount or more of the vinyl aromatic polymer component by the anionic polymerization method as the resin matrix component, the deterioration of the physical properties, which is a problem due to the flame retardant treatment, is slight, and as a result, The point is to obtain a flame-retardant resin composition having an excellent balance of fluidity and physical properties. That is, according to the vertical burning method of UL94 flame resistance test standard, 94 V-
It is possible to create different compositions that satisfy 0 (non-dropped), 94V-1 (non-dripping), and 94V-2 (dripping). In any case, flame-retardant resin with well-balanced fluidity and mechanical strength. A composition is obtained.

The components (A) and (B) are mixed and kneaded by a known device such as a kneader, Banbury mixer, single-screw or twin-screw extruder. The flame-retardant resin composition may contain higher fatty acids, higher fatty acid metal salts, polydimethylsiloxane, stabilizers such as hindered phenols, pigments, etc.
Additives such as a plasticizer and an antistatic agent can be added.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to Examples, but these do not limit the scope of the present invention in any way. The measurements in Examples and Comparative Examples were according to the methods described below. (1) Izod impact test It was measured at 23 ° C by a method according to ASTM-D256. (V notch, 1/8 inch test piece) (2) Vicat softening temperature Measured by a method according to ASTM-D1525 and used as a scale of heat resistance. (3) Melt flow rate (MFR) It was measured by a method based on ASTM-D1238 as an index of fluidity. It was determined from the extrusion amount per 10 minutes (g / 10 minutes) under the conditions of a load of 5 kg and a melting temperature of 200 ° C.

(4) Evaluation of flame retardancy VB (vertical bur) in accordance with UL-94
(1/8 inch test piece) (5) Measurement of molecular weight and analysis of branched vinyl aromatic polymer GPC chromatograph manufactured by Tosoh Corp. (HLC-
8020, built-in differential refractive index detector, separation column made by the same company (three TSKgel-GMH _XL used), light scattering detector made by the same company (LS-8000), scattering angle 5 °, light source: 5 mw (He -Ne laser), temperature 38 ° C, solvent tetrahydrofuran, sample concentration 0.1 wt / v%,
The measurement was performed at a sampling pitch of 1 / 0.4 (times / second).

As the components used in Examples and Comparative Examples, those prepared in the following Reference Examples were used. Reference Example 1 (Preparation of Radical Polymerized Rubber Modified Polystyrene A1) Polybutadiene (Nihon Zeon Co., Ltd., Nipol 122)
0SL) is dissolved in styrene, ethylbenzene and t
-Butyl peroxyisopropyl carbonate was added in a small amount, and finally a polymerization stock solution having the following composition was prepared. (Unit: parts by weight) ・ Polybutadiene 9.8 ・ Styrene 76.8 ・ Ethylbenzene 13.0 ・ t-Butylperoxyisopropyl carbonate 0.04 ・ α-Methylstyrene dimer 0.02 ・ Polydimethylsiloxane 0.10

2.2 liters / hour of the above-mentioned polymerization stock solution was placed in a 3-tank reactor with an agitator having an internal volume of 6.2 liters.
The liquid was continuously fed at r. The temperature inside the reactor was adjusted so that the solid content concentration at the outlet of the first reactor was 38% by weight. Furthermore, the internal temperature of the reactor was controlled so that the solid content concentration at the outlet of the third reactor was 80% by weight. Next, the mixture was fed into a devolatilizer under a vacuum at 230 ° C. to remove unreacted styrene and ethylbenzene, and the mixture was granulated by an extruder to obtain pellet-shaped rubber-modified polystyrene A1. The proportion of polybutadiene in A1 was 12.3% by weight. The dispersed phase weight calculated from the insoluble matter of A1 methyl ethyl ketone is 30% by weight.
And the continuous phase was 70% by weight. The weight average molecular weight and the number average molecular weight of the continuous phase determined by GPC of the methyl ethyl ketone soluble component were 220000 and 81,000, respectively. The average particle size of the dispersed phase was 1.5 μm, and the swelling index for toluene was 9.5.

Reference Example 2 (Branched polystyrene B1, B2
Preparation) The autoclave equipped with an induction stirrer that had been replaced with nitrogen was charged with 7.0 kg of styrene and 35 kg of cyclohexane, and the internal temperature was adjusted to 5
The temperature was controlled at 5 ° C. While stirring at high speed, a 10% THF solution containing 12.6 g of n-butyllithium was injected to start the reaction. After 5 minutes, the internal temperature of the reactor rose to 87 ° C. A small amount of the reaction solution was sampled and precipitated in methanol to stop the reaction. The weight average molecular weight of the prepolymer before the coupling reaction was 54,000, the number average molecular weight was 52,000, and Mw / Mn = 1.038.
Then, as a coupling agent, tetraglycidyl 1,3
A 20% THF solution containing 16 g of bisaminomethylcyclohexane (hereinafter abbreviated as TED) was injected to start the coupling reaction. The temperature inside the reactor was controlled at 70 ° C. and the coupling reaction was performed for 20 minutes. The reaction solution was taken into a large amount of methanol to recover branched polystyrene B1. From this GPC, the weight average molecular weight was 137,000 and the number average molecular weight was 110000.

The GPC chart is as shown in FIG. 1, and there were two peak distributions of the coupling polymer having a high molecular weight by TED coupling and the partially uncoupled low molecular weight polymer. Since the weight average molecular weight of the high molecular weight component was 15,000 and the weight average molecular weight of the low molecular weight uncoupled component was 54,000, polystyrene having a three-branched structure was obtained by TED coupling. It was confirmed. The reason why a tri-branched polymer is formed by tetrafunctional TED is presumably because polystyrene having terminal activity is difficult to react with the fourth epoxy group due to steric hindrance. From the area ratio of the chromatograms of the high-molecular component and the low-molecular component, the content of 3-branched polymer was 87% by weight.

In the same manner as in Reference Example 2, the polymerization catalyst n
-By adjusting the implantation amount of butyl lithium,
The prepolymer before coupling was changed to have a different weight average molecular weight, and a coupling reaction by TED was performed to obtain a 3-branched polymer B2 having a different molecular weight. B
The branching result and the melt flow rate of No. 2 are shown in Table 1.

Reference Example 3 (4-branched polystyrene B3, B
Preparation of 4) 6 kg of cyclohexane in an autoclave purged with nitrogen,
1.0 kg of styrene monomer was charged, and the internal temperature was controlled at 55 ° C. Then, a 10% THF solution containing 1.57 g of n-butyllithium was injected to initiate polymerization.
After 5 minutes, the internal temperature of the reactor rose to 83 ° C. After continuing the reaction for 20 minutes, a part of the reaction solution was sampled and GPC measurement was carried out. The weight average molecular weight of this product was 674,000. Then di (trichlorosilylyl) ethane 0.82
A 20% THF solution containing g was added and a coupling reaction was carried out for 20 minutes while controlling the internal temperature at 70 ° C.
A branched polystyrene B3 was obtained by the same treatment as in Reference Example 2. The Mw of this product had a weight average molecular weight of 272,000, and uncoupling was a trace. Mw / of this thing
Mn was 1.05, and the polystyrene was a tetra-branched structure close to monodisperse. The reason why polystyrene having a 4-branched structure was obtained by using a hexafunctional coupling agent seems to be that it is difficult to react more than 4-branched structure due to steric hindrance as in the case of using TED as a coupling agent.

Similar to the polymer of B3, 6 kg of cyclohexane and 1.0 kg of styrene monomer were reacted with 1.5 times the charged amount of n-butyllithium, and di (trichlorosilylyl) ethane was used as the coupling agent. 1.1 g
The reaction was performed using Weight average molecular weight of polymer before coupling 494,000, weight average molecular weight of 2 after coupling
0.2 million of 4-branched polystyrene B4 was obtained.

Reference Example 4 (Preparation of linear monodisperse polystyrene L1 and L2) 6.0 kg of cyclohexane and 1.0 kg of styrene monomer were charged into an autoclave at an internal temperature of 40 ° C. Then, with vigorous stirring, a 20% cyclohexane solution containing 0.52 g of n-butyllithium was charged as a polymerization initiator. After 5 minutes, the internal temperature rose to 65 ° C. 2 after the fever ends
After continuing stirring for 0 minute, the reaction solution was poured into a large amount of methanol to obtain linear polystyrene L1. L1 has a weight average molecular weight Mw of 200,500,000 and Mw / Mn of 1.0.
It was 2. Similarly, when only the amount of n-butyllithium added is set to 0.90 g, Mw 132,000, Mw / Mn = 1.0
A linear polystyrene L2 having a monodispersity of 8 was obtained.

Reference Example 5 (Linear polydisperse polystyrene L
Preparation of 3, L4) A polymerization stock solution consisting of styrene and ethylbenzene was continuously fed to the three-tank reactor used for preparation of the rubber-modified polystyrene A1, and linear polymerization polystyrene, L3 was obtained by initiation of thermal polymerization. . Table 1 shows the analysis results and the melt flow rate values. On the other hand, styrene,
A polymerization stock solution consisting of ethylbenzene, α-methylstyrene dimer and t-butylperoxyisopropyl carbonate was continuously fed to obtain linear polystyrene L4. Table 1 shows the analysis results and the melt flow rate values. Brominated epoxy resin: Asahi Ciba Co., Ltd. F55 Bromine content 59.0 wt%

[0047]

[Table 1]

Reference Example 6 (Quantification of Branched Vinyl Aromatic Polymer) For the purpose of quantifying branched PS in a polymer sample, TED was used as a coupling agent in the same manner as in Reference Example 2 to obtain M.
A tri-branched monodisperse polymer (B-7) having wL 198,000 and Mw / Mn = 1.09 was prepared. B-7 / (B-7 + 680) × 10 ² was set to 0.5, 1 by using commercially available polydisperse polystyrene Asahi Kasei Polystyrene GP680 having MwL of 207,000 and Mw / Mn = 2.00, which had a molecular weight close to that of B-7.
G dissolved in THF at a ratio of 0, 30, 50, 100
Using PCLALLS and GPCRI, MwL and
MwR is measured and the vertical axis shows MwL / MwR and the horizontal axis shows B-7.
/ (B-7 + 680) × 10 ² was taken to prepare a calibration curve, and FIG. 2 was obtained. (The reason why the tri-branched polymer is used here is that the tri-branched polymer has the smallest number of branches in the present invention.
This is because the value of wL / MwR is smaller than that when other polymers having a large number of branches are used).

[0049]

【Example】

Examples 1 to 8 and Comparative Examples 1 and 2 Table 2 shows the radical-polymerized rubber-modified polystyrene A1 prepared in Reference Example 1, the polystyrene prepared in Reference Example and the flame retardant.
The flame-retardant resin composition of the present invention was prepared by blending with the above composition, melt-kneading using a twin-screw extruder, and pelletizing. Then, the flame-retardant resin composition thus obtained was heated at a resin temperature of 220 with an injection molding machine.
Molding was carried out at 0 ° C., a test piece was prepared, and the physical properties were evaluated. The evaluation results of each test piece are shown in Table 2.

[0050]

[Table 2]

[0051]

INDUSTRIAL APPLICABILITY The flame-retardant resin composition of the present invention containing a vinyl aromatic resin component by an anionic polymerization method in a resin matrix has flame retardancy and fluidity as shown in Examples and Comparative Examples. It has an excellent balance of properties and mechanical strength. The composition of the present invention is suitable for home electric appliance parts, OA equipment parts and the like which are required to have flame retardancy, and plays a large role in these industries.

[Brief description of drawings]

FIG. 1 is a GPC chart of Reference Example 2 (branched polystyrene B1).

FIG. 2 is a calibration curve for quantification of a branched vinyl aromatic polymer.

Claims (5)

[Claims] 1. 99 to 50 parts by weight of a rubber-modified vinyl aromatic polymer in which a continuous phase is composed of a resin containing a vinyl aromatic polymer obtained by anionic polymerization as the component (A), and the component (B) is difficult. A flame-retardant resin composition comprising 1 to 50 parts by weight of a flame retardant. 2. The vinyl aromatic polymer obtained by anionic polymerization of the component (A) has a ratio of weight average molecular weight to number average molecular weight of 2.0 or less by gel permeation chromatography-differential refractive index method. The flame-retardant resin composition according to claim 1, which is a linear structure vinyl aromatic polymer having a weight average molecular weight of 50,000 to 20,000. 3. A vinyl aromatic polymer obtained by anionic polymerization of component (A) is obtained by gel permeation chromatography-light scattering method based on weight average molecular weight MwL and gel permeation chromatography based on differential refractive index method. Weight average molecular weight MwR ratio is 1.10 or more 5.0
The flame-retardant resin composition according to claim 1, which is the following branched vinyl aromatic polymer. 4. The branched vinyl aromatic polymer has a structure represented by the following formula, and the branched polymer P has a molecular weight distribution (Mw /
Mn) is a vinyl aromatic polymer having a uniform chain length of 1.5 or less, a branched vinyl having a weight average molecular weight of 120,000 to 500,000 and a molecular weight distribution (Mw / Mn) of 1.0 to 3.0. The flame-retardant resin composition according to claim 3, which is an aromatic polymer. M- (P) _n (In the formula, M is a branched nucleus of a polyfunctional residue or a polyvinyl aromatic compound residue, P is a vinyl aromatic polymer, and n is an integer of 3 to 8 and is bonded to M. Represents the number of vinyl aromatic polymers) 5. The flame-retardant resin composition according to claim 1, wherein the flame retardant of the component (B) is a halogen-based flame retardant, a halogen-based flame retardant, and antimony oxide and / or a phosphorus-based flame retardant.