JPH11116768A - High-impact styrene type flame-retardant resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-impact styrene type flame-retardant resin composition excellent in heat stability. SOLUTION: There is provided a resin composition comprising 100 pts.wt. rubber-modified styrene resin (A) containing 2-25 wt.% conjugated diene rubber in which the rate of 1,4-bonds in the butadiene unit chains of a conjugated diene rubber is at least 70 wt.%, and the reduced viscosity ηsp /C of the resin portion is 0.4-0.6 and 1-100 pts.wt. halogen-containing flame retardant (B), wherein the total content of the remaining aromatic vinyl monomer, dimer and trimer is at most 1 wt.%. In a more particular example, the temperature at which a 5 wt.% weight loss is reached when component B is subjected to a heating test (a rate of temperature rise is 10 deg.C/min) is 300 deg.C or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a styrene-based flame-retardant resin composition. More specifically, the present invention relates to an impact-resistant styrene-based flame-retardant resin composition having excellent thermal stability.

[0002]

2. Description of the Related Art Styrene-based resins are excellent in impact resistance in addition to excellent moldability.
Although it is used in various fields such as home electric appliance parts and OA equipment parts, its use is limited due to the flammability of styrene resins.

[0003] As a method of making a styrene resin flame-retardant,
For example, it is known to add a halogen-based flame retardant to a styrene-based resin, and although flame retardancy is achieved to some extent, impact resistance may be reduced due to poor thermal stability of the flame retardant. .

[0004] In recent years, the production of large thin molded products has been required for styrene resins used in such fields, and high-temperature molding has been used in order to improve fluidity. However, among polystyrene resins, polybutadiene used in rubber-modified styrene resin (HIPS) has an unsaturated bond that is easily thermally degraded.
The impact resistance of HIPS is remarkably reduced by high-temperature molding, and there is a demand for HIPS having excellent thermal stability that can withstand high-temperature molding.

On the other hand, a stabilization method in which a hindered phenol-based antioxidant is blended with a styrene-based resin (Japanese Patent Application Laid-Open No. 7-285126), a thermoplastic resin such as polyphenylene ether, a diene base rubber, an antioxidant And a technique of adding a metal deactivator to improve impact strength under a high heat history (Japanese Patent Laid-Open No. 4-339858), but improvement of thermal stability by these methods is not sufficient. Satisfactory thermal stability improvement technology is awaited. on the other hand,
Composition of rubber-modified polymer containing high cis-polybutadiene as a main component and halogen-based flame retardant (Japanese Patent Publication No. 57-26695), rubber-modified styrene-based rubber using specific amount of cis-1,4-bonded conjugated diene rubber A composition comprising a resin and a non-halogen flame retardant (JP-A-5-179064) is known. Although the composition has excellent thermal stability, the flame retardancy is not always satisfactory. A flame-retardant styrenic resin having both stability and flame retardancy has been demanded.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has a styrene-based flame-retardant resin composition which does not have the above-mentioned problems, that is, has excellent heat stability and excellent flame retardancy. The purpose is to provide goods.

[0007]

Means for Solving the Problems As a result of intensive studies on the improvement of thermal stability and impact resistance, the present inventors have found that a rubber-modified styrene resin having a specific polybutadiene structure and a specific molecular weight, Surprisingly, the thermal stability and impact resistance of the rubber-modified styrenic resin can be surprisingly controlled by controlling the flame retardant, the residual aromatic vinyl monomer and the amount of the dimer and trimer of the aromatic vinyl monomer. The inventors have found that it is possible to dramatically improve the performance, and have reached the present invention.

That is, the present invention relates to (A) a conjugated diene rubber in which the ratio of cis-1,4-bonds in the butadiene unit chain of the conjugated diene rubber is 70% by weight or more.
Rubber-modified styrene-based resin containing 5% by weight and having a reduced viscosity ηsp / C of 0.4 to 0.6 in the resin part 100
A resin composition comprising 1 part by weight and 1 to 100 parts by weight of a halogen-based flame retardant (B), and an aromatic vinyl monomer remaining in the resin composition and a dimer of an aromatic vinyl monomer And a total content of trimers of 1% by weight or less, and an impact-resistant styrene-based flame-retardant resin composition,
In particular, the above (B) is a heating test (heating rate 10 ° C /
The present invention provides an impact-resistant styrene-based flame-retardant resin composition or an impact-resistant styrene-based dripping-type flame-retardant resin composition in which the temperature when the weight is reduced by 5% by weight is 300 ° C. or less.

Hereinafter, the present invention will be described in detail.

The impact-resistant styrene-based flame-retardant resin composition of the present invention contains a specific (A) rubber-modified styrene-based resin and (B) a halogen-based flame retardant.

The above (A) is a main component of the molding resin composition and plays a role of maintaining the strength of the molded article, and (B) is a component for imparting flame retardancy to the styrene resin.

The rubber-modified styrene resin (A) is a conjugated diene rubber having a cis-1,4-bond ratio of 70% by weight or more in the butadiene unit chain of the conjugated diene rubber (referred to as high cis rubber). It contains. The ratio of the cis 1,4-bond is essentially 70% by weight,
Preferably 80% by weight or more, more preferably 90% by weight
That is all. When a conjugated diene rubber having a cis 1,4 bond ratio of less than 70% by weight (referred to as low cis rubber) is used, the thermal stability is poor due to an increase in the 1,2-vinyl bond ratio. In molding, the drop in impact resistance is remarkable. On the other hand, with regard to flame retardancy, an increase in the amount of 1,2-vinyl bond promotes a crosslinking reaction at the time of combustion, and delays dropping of a fire, resulting in drop-type flame retardancy. Lower. Also (A)
It is important that the reduced viscosity ηsp / C of the resin part is 0.4 to 0.6. If the reduced viscosity is more than 0.6, the fluidity is lowered, and high temperature molding is required, so that the rubber is deteriorated. On the other hand, if the reduced viscosity is less than 0.4, the impact resistance is lowered, which is not preferable. And (A) contains 2 to 25% by weight of the high cis rubber. If the content is less than 2% by weight, the impact resistance is poor, while if it exceeds 25% by weight, the fluidity decreases.

Further, the total content of the aromatic vinyl monomer and the dimer and trimer of the aromatic vinyl monomer remaining in the resin composition must be 1% by weight or less.
If the total exceeds 1% by weight, the compound volatilizes during combustion and acts as a fuel, so that the flame retardancy is reduced.

The resin composition (A) of the present invention may be used as (B) in a heating test (heating rate 10 ° C./min) when the temperature at which the weight is reduced by 5% by weight is 300 ° C. or less. Especially effective. Halogen-based flame retardants having relatively low thermal stability decompose during molding to produce a large amount of halogen, and thus the halogen triggers and accelerates the deterioration of the low cis rubber. The present inventors have found that they exhibit stable thermal stability without depending on the decomposition temperature of the flame retardant, and have completed the present invention.

In the present invention, the rubber-modified styrene resin (A) comprises a rubber-modified styrene resin alone or a rubber-modified styrene resin and a rubber-unmodified styrene resin,
There is no particular limitation as long as it is compatible with or homogeneously dispersed with the component (B). The rubber-modified styrenic resin refers to a polymer in which a rubbery polymer is dispersed in a matrix in a matrix composed of a vinyl aromatic polymer, and an aromatic vinyl monomer is present in the presence of the rubbery polymer. It can be obtained by adding a monomer and, if necessary, a vinyl monomer copolymerizable therewith, and subjecting the monomer mixture to known bulk polymerization, bulk suspension polymerization, solution polymerization or emulsion polymerization.

Examples of such resins include impact-resistant polystyrene, ABS resin (acrylonitrile-butadiene-styrene copolymer), and the like.

Here, the rubber-like polymer must have a glass transition temperature (Tg) of -30 ° C. or less,
If the temperature exceeds -30 ° C, the impact resistance decreases.

Examples of such rubbery polymers include conjugated diene rubbers such as polybutadiene, poly (styrene-butadiene), and poly (acrylonitrile-butadiene). It may be a rubber-like polymer in which a rubber-like polymer obtained by partially hydrogenating a diene rubber, isoprene rubber, chloroprene rubber or the like is blended.

The rubbery polymer has a Mooney viscosity (ML) of 20 to 90 measured at 100 ° C., and a 5% by weight styrene solution viscosity (5% SV) at 25 ° C. of 20 to 3
It is preferably in the range of 00 centipoise (cps). A particularly preferred range is 25 to 150 cps.

The aromatic vinyl monomer as an essential component in the graft-polymerizable monomer mixture to be polymerized in the presence of the rubbery polymer is, for example, styrene, α-methylstyrene, paramethylstyrene or the like. Yes, styrene is most preferred, but other aromatic vinyl monomers described above may be copolymerized mainly with styrene.

If necessary, one or more monomer components copolymerizable with the aromatic vinyl monomer can be introduced as components of the rubber-modified styrene resin. When it is necessary to increase oil resistance, unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile can be used.

If it is necessary to lower the melt viscosity during blending, an acrylate comprising an alkyl group having 1 to 8 carbon atoms can be used. Further, when it is necessary to further increase the heat resistance of the resin composition, α-methylstyrene, acrylic acid, methacrylic acid,
Monomers such as maleic anhydride and N-substituted maleimide may be copolymerized. The content of the vinyl monomer copolymerizable with the vinyl aromatic monomer in the monomer mixture is from 0 to 40.
% By weight.

The rubbery polymer in the rubber-modified styrenic resin is preferably 5 to 80% by weight, particularly preferably 1 to 80% by weight.
0 to 50% by weight, a graft-polymerizable monomer mixture,
Preferably 95 to 20% by weight, more preferably 90 to 5% by weight.
It is in the range of 0% by weight. Within this range, the balance between impact resistance and rigidity of the target resin composition is improved. Further, the rubber particle diameter of the styrene-based polymer is 0.1 to 5.0.
μm is preferred, and 0.2 to 3.0 μm is particularly preferred. Within the above range, impact resistance is particularly improved.

The reduced viscosity ηsp / c of the resin part (0.5 g / dl, which is a measure of the molecular weight of the rubber-modified styrenic resin,
30 ° C. measurement: toluene solution when the matrix resin is polystyrene, methyl ethyl ketone when the matrix resin is an unsaturated nitrile-aromatic vinyl copolymer)
It is necessary to be in the range of 0.40 to 0.60 dl / g, and more preferably in the range of 0.45 to 0.55 dl / g. Reduced viscosity ηs of rubber-modified styrenic resin
Means for satisfying the above requirements regarding p / c include:
Adjustment of the amount of the polymerization initiator, the polymerization temperature, the amount of the chain transfer agent and the like can be mentioned.

Here, the reduced viscosity ηsp / c is 0.40 to 0.40.
A rubber-modified styrene-based resin having 0.60 dl / g generally has excellent fluidity and flame retardancy, particularly excellent drop-type flame retardancy, but may have a reduced impact strength. On the other hand, the dispersed phase of the conjugated diene-based polymer is identified by highly grafting the vinyl aromatic monomer to the conjugated diene-based polymer using an organic peroxide having a high hydrogen abstraction ability. It is possible to produce a rubber-modified styrenic resin having an excellent particle size distribution and excellent impact strength and rigidity.

In the present invention, the halogenated flame retardant as (B) includes halogenated bisphenol, halogenated polycarbonate, halogenated bisarylalkane, halogenated bisimide, halogenated aromatic vinyl polymer,
Examples thereof include aromatic halogen compounds such as halogenated cyanurate resins and halogenated polyphenylene ethers, aliphatic halogen compounds, and aromatic / aliphatic halogen compounds such as halogenated bisalkylbisphenols, and are preferably decabromodiphenyl oxide and tetrabromo. Bisphenol A, tetrabromobisphenol A oligomer, brominated bisphenol phenoxy resin,
Brominated bisphenol-based polycarbonate, brominated polystyrene, brominated cross-linked polystyrene, brominated polyphenylene oxide, polydibromophenylene oxide, decabromodiphenyl oxide bisphenol condensate, halogen-containing phosphoric acid ester, and fluorine-based resin.

Here, in the heating test (B) effective in the present invention (heating rate of 10 ° C./min), halogen-based flame retardants whose temperature at the time of reducing 5% by weight is 300 ° C. or less are, for example, hexagonal. Halogenated aliphatic flame retardants such as bromocyclododecane, bis (dibromopropyl) tetrabromobisphenol A ether, and halogenated aliphatic / aromatic flame retardants.

In the resin composition of the present invention, if necessary, an organic phosphorus compound, red phosphorus, an inorganic phosphate, an inorganic flame retardant, etc. may be blended as a flame retardant other than the halogen flame retardant (C). be able to.

The amount of (C) is preferably 1 to 40 parts by weight, more preferably 1 to 40 parts by weight, per 100 parts by weight of (A).
20 parts by weight, most preferably 5 to 10 parts by weight.

In the present invention, if necessary, one or more flame retardants selected from a metal-containing compound, a triazine skeleton-containing compound, a novolak resin, a silicone resin, a silicone oil, silica, an aramid fiber, a fluororesin, and a polyacrylonitrile fiber. Auxiliaries (D) can be included.

In the present invention, (D) is preferably a metal oxide and / or metal powder. The metal oxide is aluminum oxide, iron oxide, titanium oxide, manganese oxide,
Magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, cobalt oxide, bismuth oxide, chromium oxide, tin oxide, antimony oxide, nickel oxide, copper oxide, tungsten oxide, etc., or a composite (alloy) thereof, The metal powder is a simple substance such as aluminum, iron, titanium, manganese, zinc, molybdenum, cobalt, bismuth, chromium, nickel, copper, tungsten, tin, antimony, or a composite thereof. Among them, antimony oxide such as antimony trioxide is most preferable.

The amount of (D) is preferably 0.001 to 40 parts by weight, more preferably 1 to 20 parts by weight, most preferably 5 to 10 parts by weight, based on 100 parts by weight of (A). is there.

The resin composition of the present invention may be, if necessary, one or more selected from saturated higher aliphatic carboxylic acids or metal salts thereof, carboxylic acid ester waxes, organosiloxane waxes, polyolefin waxes, and polycaprolactone. Two or more release agents (E) can be blended.

Among the above (E), one or more compounds selected from saturated higher aliphatic carboxylic acids or metal salts thereof are preferred.

The carboxylic acid of the saturated higher fatty acid is preferably a straight-chain saturated monocarboxylic acid having 12 to 42 carbon atoms. For example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid and the like can be mentioned. Examples of the metal of these metal salts include lithium, sodium, potassium, magnesium, calcium, aluminum, zinc and the like, and particularly preferred are zinc stearate, magnesium stearate, calcium stearate, and aluminum stearate.

The amount of (E) is preferably 0.01 to 5 parts by weight, more preferably 100 parts by weight of (A).
0.1 to 5 parts by weight, most preferably 0.3 to 1 part by weight.

In the present invention, if necessary, a copolymer resin comprising an aromatic vinyl unit and an acrylate ester unit, an aliphatic hydrocarbon, a higher fatty acid, a higher fatty acid ester, a higher fatty acid amide, a higher aliphatic alcohol, or a metal One or two or more fluidity improvers (F) selected from soaps can be blended.

The amount of (F) is preferably 0.1 to 20 parts by weight, more preferably 100 parts by weight of (A).
0.5 to 10 parts by weight, most preferably 1 to 5 parts by weight.

The aromatic vinyl unit of the copolymer resin as (F) is, for example, styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, p-bromostyrene, 2,4,5-tribromostyrene And the like, and styrene is most preferred, but the above-mentioned other aromatic vinyl monomer may be copolymerized mainly with styrene. The acrylate unit is an acrylate ester having an alkyl group having 1 to 8 carbon atoms, such as methyl acrylate and butyl acrylate.

Here, the content of the acrylate unit in the copolymer resin is preferably 3 to 40% by weight.
5-20% by weight is preferred. Also, the solution viscosity (MEK of 10% by weight of resin) which is an index of the molecular weight of the copolymer resin is used.
(Solution, measurement temperature 25 ° C.) is preferably 2 to 10 cP (centipoise). If the solution viscosity is less than 2 cP, the impact strength decreases, while if it exceeds 10 cP, the effect of improving the fluidity decreases.

The aliphatic hydrocarbon-based processing aid as (F) is liquid paraffin, natural paraffin, microwax, polyolefin wax, synthetic paraffin, or a partial oxide thereof, or a fluoride or chloride.

The higher fatty acids as (F) include saturated fatty acids other than those described in the section of the mold release agent (E), and unsaturated fatty acids such as ricinoleic acid, ricinberidic acid and 9-oxy-12-octadecenoic acid. It is.

The higher fatty acid ester (F) may be a monohydric alcohol ester of a fatty acid such as methyl phenylstearate or butyl phenylstearate, or a monohydric alcohol ester of a polybasic acid such as diester stearate of diphenylstearyl phthalate. And sorbitan monolaurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquiolate, sorbitan triolate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate , Sorbitan esters such as polyoxyethylene sorbitan monooleate, monoglyceride stearate,
Fatty acid esters of glycerin monomers such as oleic acid monoglyceride, capric acid monoglyceride, behenic acid monoglyceride, polyglycerin fatty acid esters such as polyglycerin stearate, polyglycerin oleate, polyglycerin laurate, and polyoxyethylene mono Fatty acid esters having a polyalkylene ether unit such as laurate, polyoxyethylene monostearate and polyoxyethylene monooleate; and neopentyl polyol fatty acid esters such as neopentyl polyol distearate.

The higher fatty acid amides as (F) include monoamides of saturated fatty acids such as phenylstearic acid amide, methylolstearic acid amide, methylolbehenic acid amide, coconut oil fatty acid diethanolamide, lauric acid diethanolamide, and coconut oil fatty acid diethanolamide. And N, N′-substituted monoamides such as oleic acid diethanolamide and the like.
Saturated fatty acid bisamides such as (hydroxyphenyl) stearamide, ethylenebis (stearic acid amide), ethylenebis (12-hydroxyphenyl) stearic acid amide, hexamethylenebis (12-hydroxyphenyl) stearic acid amide, and m-xylylenebis (12
-Hydroxyphenyl) stearic acid amide and the like.

The higher aliphatic alcohol as (F) is
Monohydric alcohols such as stearyl alcohol and cetyl alcohol; polyhydric alcohols such as sorbitol and mannitol; and polyoxyethylene dodecylamine and polyoxyethylene bactadecylamine. Allylated ethers having an alkylene ether unit, polyoxyethylene lauryl ether, polyoxyethylene tridodecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl ether such as polyoxyethylene oleyl ether, polyoxyethylene Polyoxyethylene alkyl phenyl ether such as ethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether;
Polyepichlorohydrin ether, polyoxyethylene bisphenol A ether, polyoxyethylene ethylene glycol, polyoxypropylene bisphenol A
It is a dihydric alcohol having a polyalkylene ether unit such as ether or polyoxyethylene polyoxypropylene glycol ether.

The metal soap as (F) is a metal salt of a higher fatty acid such as stearic acid, such as barium, calcium, zinc, aluminum or magnesium.

In the present invention, if necessary, a thermoplastic elastomer (G) can be blended. For example, polystyrene, polyolefin, polyester, polyurethane, 1,2-polybutadiene, polyvinyl chloride, etc. And the like, and a polystyrene-based thermoplastic elastomer is particularly preferable.

The amount of (G) is preferably 0.5 to 20 parts by weight, more preferably 100 parts by weight of (A).
It is 1 to 10 parts by weight, most preferably 2 to 5 parts by weight.

The above-mentioned polystyrene-based thermoplastic elastomer is a block copolymer comprising an aromatic vinyl unit and a conjugated diene unit, or a block copolymer in which the conjugated diene unit is partially hydrogenated.

The aromatic vinyl monomer constituting the block copolymer is, for example, styrene, α-methylstyrene, paramethylstyrene, p-chlorostyrene, p-bromostyrene, 2,4,5-tribromobenzene. Styrene is the most preferable, and styrene is most preferable. However, other aromatic vinyl monomers described above may be copolymerized mainly with styrene.

The conjugated diene monomer constituting the block copolymer includes 1,3-butadiene, isoprene and the like.

In the block structure of the block copolymer, a polymer block composed of an aromatic vinyl unit is represented by S, and a polymer block composed of a conjugated diene and / or a partially hydrogenated unit thereof is represented by B. When displaying with,
SB, S (BS) n (where n is an integer of 1 to 3), S
(BSB) n, where n is an integer of 1 to 2
A block copolymer or (SB) nX (where n is 3 to 6)
Integer. X is a residue of a coupling agent such as silicon tetrachloride, tin tetrachloride, and a polyepoxy compound. It is preferable to use a star-shaped (star) block copolymer having a B-part as a bonding center. Above all, SB type 2 and SBS 3
And SBSB type 4 linear block copolymers are preferred.

In the present invention, if light resistance is required, an ultraviolet absorber, a hindered amine light stabilizer, an antioxidant, an active species trapping agent, a light-blocking agent, a metal deactivator, or One or more light resistance improvers (H) selected from quenchers can be blended.

The amount of (H) is preferably 0.05 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, and most preferably 1 to 5 parts by weight based on 100 parts by weight of the component B. It is.

In the present invention, examples of preferred compositions include the following.

The conjugated diene-based rubber contains 5 to 15% by weight of a conjugated diene-based rubber in which the ratio of cis 1,4-bonds in the butadiene unit chain is 90% by weight or more, and the reduced viscosity ηsp of the resin portion. 5 to 25 parts by weight of a flame retardant represented by the formula (1) based on 100 parts by weight of a styrene resin composed of a rubber-modified styrene resin having a / C of 0.4 to 0.6 and a rubber-unmodified styrene resin. Parts, 1 to 5 parts by weight of antimony trioxide, 0.01 to 5 parts by weight of one or more compounds selected from saturated higher aliphatic carboxylic acids and metal salts thereof.

The composition thus obtained is, for example,
It is possible to perform continuous molding for a long time using an injection molding machine or an extrusion molding machine, and the obtained molded product is flame-retardant,
Excellent fluidity, heat resistance and impact resistance.

[0058]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited thereto.

In the examples and comparative examples, various measurements were performed using the following measuring methods or measuring machines.

(1) Analysis of Flame Retardant 5 g of the resin composition was dissolved in 100 ml of methyl ethyl ketone and separated using an ultracentrifuge (20,000 rpm).
m, 1 hour). Then, the supernatant obtained by separation was added with 2
A double amount of methanol was added to precipitate a resin component, and the solution portion and the resin portion were separated using an ultracentrifuge. For the solution part, use GPC (gel permeation chromatography) [manufactured by Tosoh Corporation, Japan;
HLC-8020; column, manufactured by Tosoh Corporation, two G1000HXL; mobile phase, tetrahydrofuran; flow rate, 0.8 ml / min; pressure, 60 kg
f / cm ² ; temperature INLET 35 ° C, OVEN 4
0 ° C., RI 35 ° C .; sample loop 100 ml; injected sample amount 0.08 g / 20 ml], and the area ratio of each component on the chromatogram is assumed to be the weight fraction of each component, and the remaining fragrance is determined from the area ratio. The compositions and amounts of dimeric and trimeric aromatic vinyl monomers and aromatic vinyl monomers were determined. On the other hand, for the above resin portion, using a Fourier transform nuclear magnetic resonance apparatus (proton-FT-NMR),
The ratio of integral values of aromatic protons or aliphatic protons was determined, and the amount of a thermoplastic resin such as a rubber-modified styrene resin was determined.

(2) Heating test of flame retardant (thermogravimetric balance test: TGA method) Using a Shimadzu thermal analyzer DT-40 manufactured by Shimadzu Corporation of Japan, the temperature was raised at 10 ° C./min under a nitrogen stream. The 5% weight loss temperature was determined.

(3) Reduced viscosity of rubber-modified styrene resin ηsp / C
and a mixed solvent of methanol and 2 ml of methanol.
Shake for 5 hours and centrifuge at 18000 rpm for 30 minutes at 5 ° C. The supernatant was taken out and the resin component was precipitated with methanol and then dried.

0.1 g of the resin thus obtained is
In the case of rubber-modified polystyrene, it is dissolved in toluene, and in the case of rubber-modified acrylonitrile-styrene copolymer resin, it is dissolved in methyl ethyl ketone to obtain a solution having a concentration of 0.5 g / dl. The solution falling time T ₁ (second) was measured at 30 ° C. On the other hand, the falling time T ₀ (second) of pure toluene or pure methyl ethyl ketone was measured separately using the same viscometer, and calculated by the following formula.

Ηsp / C = (T ₁ / T ₀ −1) / C C: Polymer concentration (g / dl) (4) Glass transition temperature of rubber (Tg) Molded product (3.2 mm thickness × 12.3 mm width) × 60m
m), tan δ was measured using a mechanical spectrometer (RMS-800, manufactured by Rheometrics), and the peak was defined as Tg.

Measurement conditions: Heating rate: 3 ° C./min, temperature range: −150 to 0 ° C., strain: 0.1%, frequency: 1 Hz (5) Izod impact strength: Measured at 23 ° C. according to ASTM-D256.

Unit: kgcm / cm (V notch, 1/4 inch test piece) (6) Vicat softening temperature Measured by a method in accordance with ASTM-D1525, and used as a measure of heat resistance.

(7) Melt flow rate (MFR) The melt flow rate was measured by a method in accordance with ASTM-D1238 as an index of melt fluidity. It was determined from the extruded amount per 10 minutes (g / 10 minutes) under the conditions of a load of 5 kg and a melting temperature of 200 ° C.

(8) Thermal Stability Test of Flame Retardant Resin Composition The resin composition was injected into an injection molding machine (Model IS manufactured by Toshiba Machine Co., Ltd.)
80A), cylinder temperature 230 ° C, mold temperature 60 ° C
When a test piece is prepared under the conditions described in (1), the retention ratio (%) of the Izod impact strength to the initial value of 100 when the resin composition is retained at 230 ° C. for 20 minutes in a molding machine and the initial value of the Tg of the rubber at that time The shift amount (° C.) with respect to was used as an index of thermal stability (see FIG. 1).

(9) Flame retardancy VB (Vertical Bur) conforming to UL-94
ning) method. (1/16 inch test piece) The flame retardancy levels are in the order of V-0, V-1, and V-2.

The following components were used in Examples and Comparative Examples.

(A) Styrene resin Rubber-modified styrene resin (HIPS) polybutadiene (weight ratio of cis 1,4 bond / trans 1,4 bond / 1 vinyl 1,2 bond = 95/2/3) (Nippon Zeon ( Co., Ltd., brand name Nipol 122 OSL)｝
Was dissolved in the following mixture to give a uniform solution.

Polybutadiene 10.5% by weight Styrene 74.2% by weight Ethylbenzene 15.0% by weight α-methylstyrene dimer 0.27% by weight t-butylperoxyisopropyl carbonate 0.03% by weight Is continuously supplied to a series four-stage reactor equipped with a stirrer, and the first stage has a stirring speed of 190 rpm and 126 rpm.
° C, the second stage is 50 rpm, 133 ° C, the third stage is 20 rpm
m, 140 ° C., and polymerization was performed at 20 rpm and 155 ° C. in the fourth stage. Subsequently, the polymerization liquid having a solid content of 73% was led to a devolatilizer to remove unreacted monomers and a solvent to obtain a rubber-modified aromatic vinyl resin (referred to as HIPS-1). As a result of analyzing the obtained rubber-modified aromatic vinyl resin, the rubber content was 12.1% by weight, and the weight average particle diameter of the rubber was 1.5 μm.
m, and the reduced viscosity ηsp / c was 0.53 dl / g.

By adjusting the amount of the polymerization initiator, the polymerization temperature and the amount of the chain transfer agent, the rubber modified rubber having the same rubber content and the weight average particle diameter of the rubber as HIPS-1 and having a different reduced viscosity ηsp / c. A styrenic resin was produced. The results are shown in Table 2.

On the other hand, polybutadiene having a different weight ratio of cis 1,4 bond / trans 1,4 bond / vinyl 1,2 bond in polybutadiene was used. A rubber-modified styrene resin having a rubber content, a rubber weight average particle diameter, and a reduced viscosity ηsp / c was produced. The results are shown in Table 3.

Rubber-unmodified styrene resin (GPPS) Polystyrene having a weight average molecular weight of 200,000 (produced by Asahi Kasei Kogyo Co., Ltd.) was used (referred to as GPPS).

(B) Halogen flame retardant Bis (dibromopropyl) tetrabromobisphenol A ether (FR-1) A halogen flame retardant represented by the following formula (1) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was used. The 5% weight loss temperature (designated FR-1) is 290 ° C.

[0077]

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Tris (tribromoneopentyl) phosphate (FR-2) A halogen-based flame retardant represented by the following formula (2) manufactured by Daihachi Chemical Industry Co., Ltd. was used. The 5% weight loss temperature (designated FR-2) is 310 ° C.

[0079]

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Ethylene bis (tetrabromophthalimide) (FR-3) A halogen-based flame retardant represented by the following formula (3) manufactured by Albemarle was used. The 5% weight loss temperature (designated FR-3) is 440 ° C.

[0081]

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(C) Flame retardant aid Antimony trioxide (Sb ₂ O ₃ ) manufactured by Suzuhiro Chemical Co., Ltd. was used.

[0083]

Examples 1-2 and Comparative Examples 1-2 Polystyrene containing a large amount of residual styrene monomer and oligomer (styrene dimer and trimer) was produced by changing the polymerization temperature and the amount of chain transfer agent. And HIPS-1 were blended with HIPS obtained by purification to produce rubber-modified polystyrene having different amounts of residual styrene monomer and oligomer. Then, it was compounded at the composition ratio shown in Table 1 and a side-feedable twin-screw extruder (cylinder inner diameter D = 40 mm)
(Φ, L / D = 46), and melt extrusion was performed at 230 ° C.

A test piece was prepared from the pellet thus obtained using an injection molding machine (Model IS80A, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 230 ° C. and a mold temperature of 60 ° C., and evaluated for flame retardancy. Was performed. The results are shown in Table 1.

According to Table 1, it is found that the flame retardancy is greatly improved by reducing the residual styrene monomer and oligomer in the resin composition to 1% by weight or less.

[0086]

[Table 1]

[0087]

Examples 3-6, Comparative Examples 3-4 Reduced viscosity η shown in Table 2
HIPS with different sp / C are used, and the total content of residual styrene monomer, styrene dimer and trimer is 0.
5% by weight was mixed at the composition ratio shown in Table 2, and the same experiment as in Example 1 was performed to evaluate. The results are shown in Table 2.

According to Table 2, the total content of the residual styrene monomer, styrene dimer and trimer in the molded product was 1.
At 0 wt% or less, ηsp / C of HIPS is 0.4 to 0.1.
It can be seen that when it is in the range of 6, the balance characteristics of fluidity, impact resistance and flame retardancy are improved.

[0089]

[Table 2]

[0090]

Examples 7 to 12, Comparative Examples 5 to 6 HIPS having different amounts of cis 1,4-bonds in the rubbers shown in Table 3 and thermal stability (5
Examples 1 and 2 were prepared by using halogen-based flame retardants having different weight percent reduction temperatures, and adjusting the total content of the residual styrene monomer, styrene dimer and trimer to 0.5% by weight. Similarly, a composition was prepared and the thermal stability was evaluated. The results are shown in Table 3.

According to Table 3, it is found that the thermal stability is remarkably improved when HIPS of the high cis rubber is used. Also, among the halogen-based flame retardants, the 5% by weight reduction temperature is 30%.
HI of flame retardant of 0 ° C or less and high cis rubber used in the present invention
In combination with PS, the effect of improving thermal stability is the largest.

[0092]

[Table 3]

[0093]

Examples 13 and 14, Comparative Examples 7 and 8 HIPS having different amounts of cis 1,4-bonds in the rubbers shown in Table 4 and residual styrene monomer, total amount of styrene dimer and trimer are contained. A composition was prepared in the same manner as in Example 1 so that the amount was 0.5% by weight, and the flame retardancy was evaluated. The results are shown in Table 4.

According to Table 4, when the amount of cis 1,4-bond decreases, the amount of 1,2-vinyl bond increases with the decrease, so that the cross-linking reaction is accelerated during combustion and the drop-type flame retardancy decreases. You can see that.

[0095]

[Table 4]

[0096]

The styrenic flame-retardant resin composition of the present invention comprises:
An impact-resistant styrene-based flame-retardant resin composition having excellent thermal stability.

The styrenic flame-retardant resin composition is VT
R, distribution board, television, audio player, condenser, household outlet, boombox, video cassette, video disk player, air conditioner, humidifier, electric home appliance housing such as electric hot air machine, chassis or parts, CD-ROM main Frame (mechanical chassis), printer, fax, PPC, CRT, word processor copier, electronic cash register, office computer system, floppy disk drive, keyboard, type, ECR, calculator, toner cartridge, OA equipment housing such as telephone, Chassis or parts, connector, coil bobbin, switch, relay, relay socket, LED, variable condenser, AC adapter, FBT high-voltage bobbin, FBT case, IFT coil bobbin, jack, volume shaft, motor Suitable for electronic and electrical materials such as electrical components, and automotive materials such as instrument panels, radiator grills, clusters, speaker grills, louvers, console boxes, defroster garnishes, ornaments, fuse boxes, relay cases, connector shift tapes, etc. And play a large role in these industries.

[Brief description of the drawings]

FIG. 1 In a thermal stability test of a resin composition (Comparative Example 6), a shift amount (° C.) with respect to an initial value of Tg of rubber when a resin composition is kept at 230 ° C. for 20 minutes in a molding machine is determined. The method is shown. The temperature at the peak top of tan δ without stagnation (-87.0 ° C.) and its temperature with stagnation (−
78.2 ° C.) as an index of thermal stability.

Claims (3)

[Claims] 1. The conjugated diene rubber has a cis-1,4-bond content of 70% by weight in the butadiene unit chain.
The conjugated diene-based rubber described above is contained in an amount of 2 to 25% by weight, and the reduced viscosity ηsp / C of the resin portion is 0.4 to 0.1%.
A resin composition comprising 100 parts by weight of a rubber-modified styrenic resin which is No. 6 and (B) 1 to 100 parts by weight of a halogen-based flame retardant, wherein the aromatic vinyl monomer and fragrance remaining in the resin composition An impact-resistant styrene-based flame-retardant resin composition, characterized in that the total content of dimers and trimers of an aromatic vinyl monomer is 1% by weight or less. 2. The impact resistance according to claim 1, wherein the temperature at which the halogen-based flame retardant (B) loses 5% by weight in a heating test (heating rate: 10 ° C./min) is 300 ° C. or less. Styrene-based flame-retardant resin composition. 3. The flame-retardant impact-resistant styrene-based resin composition according to claim 2.