JP2012057009A - Rubber-modified polystyrene-based flame-retardant resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber-modified polystyrene-based flame-retardant resin composition and a molding in which the using for the application of an internal part, an exterior material or the like of OA equipment or a liquid crystal television, which receives thermal history over a long period of time is possible.SOLUTION: The flame-retardant resin composition includes, based on (A) 100 pts.mass of a rubber-modified polystyrene resin, (B) 15-22 pts.mass of a bromine-based flame retardant of 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine, and (C) 2.3-3.7 pts.mass of an antimony trioxide. Further, the rubber-modified polystyrene-based flame-retardant resin composition comprises blending (D) 2,700-12,000 ppm of a phenolic antioxidant of octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and/or triethylene glycol-bis [3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] as the addition concentration of the mass standard based on the whole flame-retardant resin composition into the flame-retardant resin composition.

Description

The present invention relates to a rubber-modified polystyrene-based flame retardant resin composition and a molded article having high flame retardancy and excellent long-term heat resistance.

Conventionally, rubber-modified polystyrene resins have been used in the field of food packaging materials such as foamed sheets and sundries, and have many applications in fields where durability and heat resistance over a long period of time are not particularly required. For applications that receive a certain degree of thermal history over a long period of time, such as internal parts and exterior materials for office automation equipment and LCD TVs, ABS resin (acrylonitrile-butadiene-styrene resin) and PC / ABS resin (polymer alloy of polycarbonate resin and ABS resin) In these cases, improvement of long-term stability has been attempted (Japanese Patent No. 4017053). In recent years, due to the demand for cost reduction, rubber-modified polystyrene resins have been adopted instead of these resins. As a result, even rubber-modified polystyrene resins are required to have durability that was not particularly required in the past. Even in the flame-retardant styrene-based resin composition, an improvement to keep the yellowing due to long-time irradiation of light low is being attempted (Japanese Patent Laid-Open No. 2000-034377).

Japanese Patent No. 4017053 JP 2000-034377 A

Flame retardant properties are often required for applications such as internal parts and exterior materials for office automation equipment and liquid crystal televisions, but when rubber-modified polystyrene resins are used as flame retardant compositions containing flame retardants such as halogens. The rubber property-modified polystyrene flame retardant resin composition capable of maintaining the physical properties over a long period of time has not been known.

２．ＪＩＳ Ｋ ７１３９に基づき作成した試験片を温度７０℃で２０００時間加熱した際の引張歪の保持率およびシャルピー衝撃強度の保持率が５０％以上を有する上記１．に記載のゴム変性ポリスチレン系難燃樹脂組成物。
３．１．５ｍｍ厚みの試験片の加熱前および温度７０℃で２０００時間加熱した際のＵＬ９４燃焼試験で難燃性がいずれもＶ−０である上記１．に記載のゴム変性ポリスチレン系難燃樹脂組成物。
４．ＪＩＳ Ｋ ７１３９に基づき作成した試験片を温度７０℃で２０００時間加熱した際の引張歪の保持率およびシャルピー衝撃強度の保持率が５０％以上を有し、かつ１．５ｍｍ厚みの試験片の加熱前および温度７０℃で２０００時間加熱した際のＵＬ９４燃焼性試験での難燃性がＶ−０である上記１．に記載のゴム変性ポリスチレン系難燃樹脂組成物。
５．上記１．乃至上記４．に記載のいずれかのゴム変性ポリスチレン系難燃樹脂組成物からなる成形体。
６．上記１．乃至上記４．に記載のいずれかのゴム変性ポリスチレン系難燃樹脂組成物を用いた電気・電子機器筐体または内部部品。 As a result of intensive studies on the above problems, the present inventor has selected a specific flame retardant and a specific phenolic antioxidant and completed the present invention by using a specific amount.
1. (A) 15 to 22 parts by mass of a brominated flame retardant represented by structural formula (I) and (C) 2.3 to 3.7 parts by mass of antimony trioxide with respect to 100 parts by mass of rubber-modified polystyrene resin. In addition to the flame retardant resin composition contained, 2700 to 12000 ppm of (D) a phenolic antioxidant represented by the structural formula (II) and / or (III) as a mass-based additive concentration with respect to the entire flame retardant resin composition A rubber-modified polystyrene-based flame retardant resin composition.

2. 1. A tensile strain retention rate and a Charpy impact strength retention rate of 50% or more when a test piece prepared based on JIS K 7139 is heated at a temperature of 70 ° C. for 2000 hours. The rubber-modified polystyrene-based flame retardant resin composition described in 1.
3. The flame retardancy is V-0 in the UL94 combustion test before heating a 1.5 mm-thick test piece and at a temperature of 70 ° C. for 2000 hours. The rubber-modified polystyrene-based flame retardant resin composition described in 1.
4). Heating of a test piece having a tensile strain retention ratio and a Charpy impact strength retention ratio of 50% or more when a specimen prepared according to JIS K 7139 is heated at a temperature of 70 ° C. for 2000 hours, and having a thickness of 1.5 mm The flame resistance in the UL94 flammability test when heated at a temperature of 70 ° C. before and at a temperature of 70 ° C. is V-0. The rubber-modified polystyrene-based flame retardant resin composition described in 1.
5. Above 1. Thru 4. A molded article comprising any one of the rubber-modified polystyrene-based flame retardant resin composition described in 1.
6). Above 1. Thru 4. Electrical / electronic equipment casings or internal parts using any of the rubber-modified polystyrene-based flame retardant resin compositions described in 1.

According to the present invention, a rubber-modified polystyrene flame retardant resin composition using a halogen-based flame retardant represented by the structural formula (I) and a phenol-based antioxidant represented by the structural formula (II) and / or the structural formula (III). The durability of the product is greatly improved, and it is advantageous to use it in applications that receive heat history over a long period of time, such as internal parts and exterior materials of OA equipment and liquid crystal televisions.

The rubber-modified polystyrene resin (HIPS) used in the present invention is a product obtained by dissolving a rubber component in a styrene monomer and polymerizing it with stirring using a polymerization initiator such as thermal polymerization or peroxide. As such, batch polymerization or continuous polymerization may be used. As the rubber component, a homopolymer of butadiene or a copolymer with styrene copolymerizable with butadiene is used, and the molecular structure of the copolymer may be a random structure or a block structure, and has a branched structure. Also good. Such a rubber-modified polystyrene resin may be used in combination with polystyrene (GPPS) not containing a rubber component for the purpose of adjusting the amount of rubber component, impact strength, and fluidity of the resin composition.

The brominated flame retardant used in the present invention is a brominated flame retardant represented by the structural formula (I) {2,4,6-tris (2,4,6-tribromophenoxy) -1,3,5-triazine}. For example, it is a product known as the trade name Piroguard SR245 (Daiichi Kogyo Seiyaku Co., Ltd.).

The flame retardant of the structural formula (I) has a melting point of about 230 ° C., and melts at the processing temperature of polystyrene resins such as general polystyrene and rubber-modified polystyrene resin, so that dispersion in resin kneading is easy. The appearance of the molded product used is good.

Although the addition amount of the flame retardant of the structural formula (I) can be adjusted according to the required flame retardant level, 15 to 22 parts by mass with respect to 100 parts by mass of the rubber-modified polystyrene resin is essential, preferably 16 to 21 parts. When the amount of the flame retardant is less than 15 parts, the flame retardancy is inferior and the V-0 level in the UL94 combustion test cannot be secured. On the other hand, if the amount is more than 22 parts, the V-0 level in the UL94 combustion test is satisfied, but the retention effect of tensile strain and impact characteristics is deteriorated and the heat resistance is also lowered. When other flame retardants are used, it is difficult to maintain the physical properties after long-term heating, and the flame retardancy tends to decrease.

In the present invention, a flame retardant aid is used together with the flame retardant. As the flame retardant aid, it is essential to use 2.3 to 3.7 parts by mass of antimony trioxide, and preferably 2.6 to 3.5 parts by mass. When the amount of antimony trioxide is less than 2.3 parts by mass, the combustion time becomes long and flame retardancy cannot be ensured. On the other hand, if the amount is more than 3.7 parts, the glowing (fire type time) becomes long and flame retardancy cannot be ensured.

The phenolic antioxidant used in the present invention is the structural formula (II) {octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate}, structural formula (III) {triethylene glycol- Bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate]} is used alone or in combination. For example, structural formula (II) is known as trade name IRGANOX1076, and structural formula (III) is known as trade name IRGANOX245 (both manufactured by Ciba Specialty Chemicals). These are specified amounts at the production stage of rubber-modified styrene resin (in batch polymerization, beads are extruded and pelletized. In continuous polymerization, pelletized immediately before or after the devolatilization step). It may be added in advance, or may be added in the step of compounding the flame retardant with the resin.

Phenol-based antioxidants are often used as primary antioxidants in an amount of about 0.05 parts by mass with respect to the resin composition. However, such an added amount maintains the physical properties when heated for a long time as shown in the present invention. Has no effect. The addition amount of the phenolic antioxidant represented by the structural formula (II) and the structural formula (III) is such that the total amount of the phenolic antioxidant is based on the weight of the whole flame retardant resin composition even when used alone or in combination. The addition concentration is 2700 to 12000 ppm, preferably 3100 to 10000 ppm. If it is less than 2700 ppm, the flame retardancy when heated at a temperature of 70 ° C. for 2000 hours is deteriorated. In addition, other antioxidants to the extent that they are added in the production stage of general rubber-modified styrenic resins may be included, but when a large amount of other antioxidants are used to solve the problems of the present invention It is difficult to maintain the physical properties after long-term heating, and the flammability tends to decrease.

In the measurement of tensile strain and Charpy impact strength in the present invention, a test piece prepared based on JIS K 7139 was used. Each physical property retention rate is a value obtained by measuring a physical property value after heating for 2000 hours at a temperature of 70 ° C. and expressed as a percentage of the physical property value for 0 hour (before heating).
The tensile strain was measured based on JIS K 7162, and the Charpy impact strength was measured based on JIS K 7111-1. The deflection temperature under load (HDT) was used as an index of heat resistance, and measurement was performed based on JIS K 7191-2 (A method, flatwise).

The internal parts and exterior materials of office automation equipment and liquid crystal televisions are usually used at room temperature or higher and deflection temperature under load (HDT). At a temperature near room temperature, even if a test piece for physical property testing is held for a long period of time, the deterioration with time of the physical property changes gradually, and a significant difference is unlikely to appear. In the present invention, a temperature of 70 ° C. close to the deflection temperature under load (HDT) of the resin composition is adopted as an accelerating condition for thermal deterioration, and the physical property retention rate after heating for 2000 hours is used as an index of durability. As a standard of the physical property retention rate, the retention rate 50% exemplified in JIS K 7226 (Plastic-Time after long-term heat exposure-Determination of temperature limit) was determined to be 50%.

The composition of the present invention can be obtained by melt-kneading a resin, a flame retardant, a flame retardant aid, and an antioxidant blended in a specified composition with an extruder. For example, at the time of extrusion, a resin and a chemical compounded to have a prescribed composition are sufficiently mixed with a tumbler, a Henschel mixer, etc., and then supplied to an extruder to form a strand, which may be pelletized with a pelletizer. . Further, components other than the resin may be continuously supplied separately to the extruder according to the supply amount of the resin and extruded. In this case, polyethylene wax, fatty acid metal salt, ethylene bisstearylamide, mineral oil, etc. may be used as a release agent or lubricant, and an antistatic agent, an ultraviolet absorber, a colorant such as titanium oxide or carbon black. Further, modifiers such as inorganic fillers such as talc, calcium carbonate and glass fiber, and elastomer components (SBS and hydrogenated SBS) may be added.

The composition of the present invention is a rubber-modified styrene-based flame retardant resin composition with greatly improved durability, such as internal parts of electrical / electronic devices such as OA devices and liquid crystal televisions, exterior materials such as housings, etc. It is suitable for molded products that receive a heat history over a long period of time. Although there is no restriction | limiting in particular in a shaping | molding method, Injection molding is suitable.

Hereinafter, details will be described by way of examples, but the present invention is not limited thereto.

Rubber-modified polystyrene resin: HIPS having a weight average molecular weight of 180,000 and a rubber amount of 8.6% and GPPS having a weight average molecular weight of 240,000 were used in a mass ratio of 8: 2.

Brominated flame retardants: trade name Piroguard SR245 (Daiichi Kogyo Seiyaku Co., Ltd., structural formula (I)) and trade name SAYTEX 8010 [Albemarle Japan Co., Ltd., structural formula (IV): ethylenebispentabromobenzene] are used. It was.

Flame retardant aid: Trade name AT-3CN (antimony trioxide) manufactured by Suzuhiro Chemical Co., Ltd. was used.

Phenol-based antioxidants: trade name IRGANOX 1076 (the structural formula (II)), trade name IRGANOX 245 (the structural formula (III)), and trade name IRGANOX 1520L {the following structural formula (V): 2, 4-bis [(octylthio) ) Methyl] -O-cresol] (all manufactured by Ciba Specialty Chemicals).

Titanium oxide: Trade name CR-90-2 (Ishihara Sangyo Co., Ltd.) was used.

(Preparation of resin composition)
With respect to 100 parts by mass of the rubber-modified polystyrene resin, the flame retardant and the flame retardant aid used the mass parts shown in Tables 1 to 3, and the titanium oxide used 4 parts by mass. The antioxidant was measured and used so that it might become the density | concentration of Table 1-Table 3 with respect to the whole flame-retardant resin composition. All these components are mixed in a Henschel mixer (Mitsui Miike Chemical Co., Ltd., FM20B), supplied to a twin-screw extruder (Nippon Steel Works, TEM26SS) to form a strand, water cooled, and then into a pelletizer. Guided pelletized. At this time, the cylinder temperature was 230 ° C. and the supply amount was 30 kg / hour. The obtained pellets were dried by heating at a temperature of 70 ° C. for 3 hours, and then an A-type test piece (dumbbell) described in JIS K 7139 was molded by an injection molding machine (manufactured by Nippon Steel Works, Ltd., J100E-P). did. At this time, the cylinder temperature was 205 ° C. and the mold temperature was 45 ° C. The Charpy test piece was cut out from the center of the dumbbell piece, cut into a notch (type A, r = 0.25 mm), and used for the test. The deflection temperature under load (HDT) of the resin composition was measured based on JIS K 7191-2 (Method A, flatwise) using a test piece cut out from the center of the dumbbell piece.

(Heating test)
The obtained dumbbell pieces and Charpy pieces were put into a blower dryer (model name DF-62, manufactured by Yamato Co., Ltd.) set at a temperature of 70 ° C., taken out after heating for 2000 hours, measured for physical properties, and measured separately before heating. The ratio with respect to the physical property value was obtained as a percentage and used as the retention rate. The tensile strain was measured based on JIS K 7162, and the Charpy impact strength was measured based on JIS K 7111-1. The physical property retention rate at each predetermined time is shown in Tables 1 to 3.

(Combustion quality)
A combustion test was performed on a 1.5 mm-thickness combustion test piece based on the subject No. 94 vertical combustion test method (UL94) of US Underwriters Laboratories. The results are shown in Tables 1 to 3.

(About each example and comparative example)
Examples 1-4, 5-8, and 9-10 ensure a physical property retention of 50% or more after long-term heating by using the flame retardant and addition amount of the present invention and addition amount of antioxidant and antioxidant species. It is possible to show that flammability is maintained. Comparative Example 1 shows that the physical properties after long-term heating cannot be maintained without adding an antioxidant, and the combustibility is also deteriorated. Comparative Examples 2 and 4 show that if the antioxidant addition amount is below the lower limit of the addition amount of the antioxidant, the physical properties after long-term heating can be maintained, but the combustibility is deteriorated. Comparative Examples 3 and 5 indicate that when the antioxidant addition amount exceeds the upper limit, the physical properties and the combustibility are maintained, but the heat resistance is not satisfied.
Comparative Example 6 shows a decrease in flame retardancy when the amount of flame retardant falls below a prescribed lower limit, and Comparative Example 7 shows a decrease in flame retardance when the amount of flame retardant aid falls below the lower limit. Comparative Example 8 shows a decrease in flame retardancy with an excess of flame retardant aid, and Comparative Example 9 shows that although the flame retardancy is satisfactory with an excess of flame retardant, the heat resistance is reduced. Comparative Example 10 shows that when a flame retardant different from the present invention is used, the physical properties after long-term heating are significantly reduced and the flame retardancy cannot be maintained. Comparative Example 11 shows that physical properties and combustibility cannot be maintained when an antioxidant different from the present invention is used.

According to the present invention, the rubber-modified polystyrene flame retardant resin composition using the halogen-based flame retardant represented by the general formula (I) and the general formula (II) and / or the general formula (III) has greatly improved durability. However, it is advantageous to use in applications that receive heat history over a long period of time, such as internal parts and exterior materials of OA equipment and liquid crystal televisions.

Claims (6)

(A) 15 to 22 parts by mass of a brominated flame retardant represented by structural formula (I) and (C) 2.3 to 3.7 parts by mass of antimony trioxide with respect to 100 parts by mass of rubber-modified polystyrene resin. In addition to the flame retardant resin composition contained, 2700 to 12000 ppm of (D) a phenolic antioxidant represented by the structural formula (II) and / or (III) as a mass-based additive concentration with respect to the entire flame retardant resin composition A rubber-modified polystyrene-based flame retardant resin composition.

The rubber-modified polystyrene-based flame retardant according to claim 1, wherein a tensile strain retention rate and a Charpy impact strength retention rate when a test piece prepared based on JIS K 7139 is heated at a temperature of 70 ° C for 2000 hours have a retention rate of 50% or more. Resin composition. The rubber-modified polystyrene-based flame retardant resin composition according to claim 1, wherein flame retardance is V-0 in a UL94 combustion test before heating a test piece having a thickness of 1.5 mm and at a temperature of 70 ° C for 2000 hours. object. Heating of a test piece having a tensile strain retention ratio and a Charpy impact strength retention ratio of 50% or more when a specimen prepared according to JIS K 7139 is heated at a temperature of 70 ° C. for 2000 hours, and having a thickness of 1.5 mm The rubber-modified polystyrene-based flame-retardant resin composition according to claim 1, wherein the flame-retardant property in the UL94 flammability test when heated at a temperature of 70 ° C before and at a temperature of 70 ° C is V-0. A molded body comprising the rubber-modified polystyrene-based flame retardant resin composition according to any one of claims 1 to 4. An electrical / electronic equipment casing or an internal part using the rubber-modified polystyrene-based flame retardant resin composition according to any one of claims 1 to 4.