JP6078326B2 - Styrenic flame retardant resin composition and molded article comprising the same - Google Patents

Description

The present invention provides a styrene-based flame retardant resin composition having flame retardancy of V-2 according to the UL94 standard and excellent in dripping acceleration at the time of ignition and melting, and a molded body comprising the same.

Styrenic resins are used in a wide range of applications by taking advantage of their properties. Among them, styrene flame retardant resins imparted with flame retardancy are used in various fields such as OA equipment such as personal computers, printers and copying machines, home appliances such as TV and audio. As a method for making a styrene resin flame-retardant, it is known to add a flame retardant such as a halogen-based resin, a phosphorus-based resin, or a metal salt to the styrene-based resin. In general, in order to increase the flame retardancy, a method of increasing the amount of the flame retardant added to the material is taken, but an increase in the amount of the flame retardant is not preferable because it causes a decrease in physical properties. Further, since the increase in the amount of the flame retardant also increases the load on the environment, it is required to achieve the desired flame retardancy using as little flame retardant as possible. Thus, various styrene resin compositions have been studied so far for the purpose of reducing the flame retardant.

Conventionally, with styrene-based flame retardant resins, dripping acceleration during ignition melting is achieved by blending styrene-based resins with halogenated flame retardants such as brominated epoxy compounds and bromophosphates and polyorganosiloxanes with specific viscosities. Has been reported (see Patent Documents 1 and 2). However, since brominated epoxy compounds and bromophosphoric acid esters have a melting point or softening point as low as 200 ° C. or lower, they are not preferred when used for parts requiring high heat resistance such as electronic equipment and OA equipment.

JP-A-9-143333 Japanese Patent Laid-Open No. 10-110076

In view of such a current situation, the present invention solves the above-mentioned problems, has a flame retardancy of V-2 according to the UL94 standard, and is excellent in dripping acceleration at the time of ignition melting. And a molded body comprising the same.

The present invention is a styrene flame retardant resin composition comprising (A) a styrene resin, (B) polylactic acid, (C) a brominated diphenylalkane compound, and (D) a flame retardant aid. (B) 0.2 to 50.0 parts by mass of polylactic acid, (C) 4 to 15 parts by mass of brominated diphenylalkane compound, and (D) flame retardant aid, relative to 100 parts by mass of (A) styrene resin. It is characterized by 0.3 to 3.0 parts by mass of the agent.

Moreover, this invention provides the molded object characterized by being obtained by shape | molding the said styrene-type flame retardant resin composition.

Since the styrene-based flame retardant resin composition obtained in the present invention is excellent in dripping acceleration at the time of ignition and melting, it can be used in OA equipment and home appliance parts that require flame retardancy of V-2 in UL94 standards. Become advantageous.

The (A) styrene resin used in the present invention is obtained by radical polymerization of an aromatic vinyl compound monomer. If necessary, a conjugated diene rubber-like polymer is added to modify the rubber. You may go. As the polymerization method, it can be produced by a known method, for example, a bulk polymerization method, a bulk / suspension two-stage polymerization method, a solution polymerization method or the like. As the aromatic vinyl compound monomer, known monomers such as styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene can be used, and styrene is preferable. In addition, monomers other than styrene-based monomers such as acrylonitrile, (meth) acrylic acid, (meth) acrylic acid ester and maleic anhydride which can be copolymerized with these aromatic vinyl compound-based monomers, What is necessary is just a grade which does not impair the performance of a styrene resin composition. Furthermore, in the present invention, a polymer obtained by adding a crosslinking agent such as divinylbenzene to a styrene monomer may be used.

Examples of the conjugated diene rubbery polymer used for rubber modification of the styrene resin of the present invention include polybutadiene, styrene-butadiene random or block copolymers, polyisoprene, polychloroprene, styrene-isoprene random, block. Or a graft copolymer, an ethylene-propylene rubber, an ethylene-propylene-diene rubber, etc. are mentioned, but a random, block or graft copolymer of polybutadiene or styrene-butadiene is particularly preferable. These may be partially hydrogenated.

Examples of such (A) styrene resin include polystyrene (GPPS), high impact polystyrene (HIPS), ABS resin (acrylonitrile-butadiene-styrene copolymer), AS resin (acrylonitrile-styrene copolymer), MS resin (methyl methacrylate-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), AES resin (acrylonitrile-ethylenepropylene-styrene copolymer), MBS resin (methyl methacrylate-butadiene-styrene copolymer) Polymer) and the like.

As the (B) polylactic acid used in the present invention, poly (L-lactic acid), poly (D-lactic acid) and copolymers or mixtures thereof are used. From the viewpoint of reducing carbon dioxide emissions, plant-derived materials are preferred.

In the case of (B) polylactic acid mainly composed of poly (L-lactic acid), the heat resistance varies depending on the ratio of the D-lactic acid component. In the present invention, considering the heat resistance of the molded article, the proportion of the D-lactic acid component is preferably less than about 5.0 mol%.

As for the molecular weight of (B) polylactic acid, it is preferable that a weight average molecular weight (Mw) is 50,000-300,000, More preferably, it is 80,000-250,000, Most preferably, it is the range of 100,000-200,000. When the weight average molecular weight (Mw) is less than 50,000, the molded article is inferior in mechanical properties and heat resistance, and when it exceeds 300,000, the moldability is lowered, which is not preferable.

In the present invention, when (A) the styrene resin is 100 parts by mass, (B) the polylactic acid is 0.2 to 50 parts by mass. (B) If the polylactic acid is less than 0.2 parts by mass, sufficient dripping accelerating properties are not expressed, and if it exceeds 50 parts by mass, the flame retardancy deteriorates due to a decrease in the proportion of the flame retardant component in the composition. It is not preferable. More preferably, it is 0.2-20 mass parts, Most preferably, it is 0.5-10 mass parts.

The (C) brominated diphenylalkane compound used in the present invention is a compound represented by the following general formula (1).

（ここで、ＲはＣ_ｎＨ_２ｎ（ｎは１〜１０の整数）の構造のアルキレン基、Ｘ_１およびＸ_２はそれぞれ独立に整数１〜５の臭素原子でありＸ_１＋Ｘ_２≧２を表す。）

(Where R is an alkylene group having a structure of C _n H _2n (n is an integer of 1 to 10), X ₁ and X ₂ are each independently a bromine atom of an integer of 1 to 5, and X ₁ + X ₂ ≧ 2) Represents.)

(C) As brominated diphenylalkane compounds, dibromomethane, 1,2-diphenylethane, 1,3-diphenylpropane, 1,6-diphenylhexane and other dibromo-substituted, tribromo-substituted, tetrabromo-substituted, pentabromo-substituted, Examples include hexabromo-substituted, heptabromo-substituted, octabromo-substituted, nonabromo-substituted, and decabromo-substituted. Preferred are octabromo-substituted, nonabromo-substituted and decabromo-substituted diphenylalkanes, and particularly preferred is decabromodiphenylethane.

In the present invention, when (A) the styrene-based resin is 100 parts by mass, the amount of (C) brominated diphenylalkane compound is 4 to 15 parts by mass. (C) When there are few brominated diphenylalkane compounds than 4 mass parts, the flame retardance of a composition will deteriorate. Moreover, when it exceeds 15 mass parts, since a composition will not dripped at the time of ignition melting, dripping acceleration | stimulation property will not be expressed. Preferably it is 4-12 mass parts, Most preferably, it is 6-10 mass parts.

(D) Flame retardant aids include, for example, antimony trioxide, antimony tetroxide, antimony pentoxide, sodium antimonate, etc. as antimony oxide, zinc borate, barium metaborate, anhydrous zinc borate, anhydrous boric acid as boron compounds Stannic oxide, zinc stannate, zinc hydroxystannate, etc. as tin compounds, molybdenum oxide, ammonium molybdate, etc. as zirconium compounds, zirconium oxide, zirconium hydroxide, etc. as zirconium compounds, and zinc compounds Examples thereof include zinc sulfide. Among them, it is particularly preferable to use antimony trioxide.

(D) The flame retardant auxiliary is added in an amount of 0.3 to 3.0 parts by weight, preferably 0.3 to 2.0 parts by weight, particularly preferably 0 with respect to 100 parts by weight of the (A) styrenic resin. .5 to 2.0 parts by mass is preferable. (D) When the addition amount of the flame retardant aid is less than 0.3 parts by mass with respect to (A) the rubber-modified styrene resin, the flame retardancy is inferior, and when it exceeds 3.0 parts by mass, the glowing behavior during combustion Is not preferable.

The styrene flame retardant resin composition of the present invention includes various additives such as dyes, pigments, anti-coloring agents, lubricants, antioxidants, anti-aging agents, and light stabilizers within the scope of the present invention. Further, known additives such as antistatic agents, fillers and compatibilizing agents, colorants such as titanium oxide and carbon black, and modifiers such as elastomer components (SBS and hydrogenated SBS) can be added. These addition methods are not particularly limited, and are known methods, for example, (A) the styrene-based resin to be used before the start of polymerization, with respect to the reaction solution during the polymerization, or after the end of the polymerization, and (B) When blending polylactic acid, (C) brominated diphenylalkane compound, and (D) flame retardant aid, they can also be added in an extruder or molding machine.

A known mixing technique can be applied to the method for mixing the styrene-based flame retardant resin composition of the present invention. For example, a uniform styrene-based flame retardant resin composition is obtained by further melt-kneading a mixture preliminarily mixed with a mixing apparatus such as a mixer-type mixer, a V-type blender, and a tumbler-type mixer. I can do it. There is no particular limitation on melt kneading, and a known melting technique can be applied. Suitable melt kneaders include Banbury mixers, kneaders, rolls, single screw extruders, special single screw extruders, and twin screw extruders. Furthermore, there is a method of separately adding an additive such as a flame retardant from the middle of a melt-kneading apparatus such as an extruder.

There is no particular limitation on the molding method for obtaining a molded product from the styrene-based flame retardant resin composition of the present invention, but injection molding is preferable, and injection molding such as a toner cartridge container is particularly preferable.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

In Examples and Comparative Examples, (A) rubber-modified polystyrene resin (HIPS) was used as the styrene resin. The rubber-modified polystyrene resin uses a high-cis polybutadiene rubber containing cis 1,4 bonds in a ratio of 90 mol% or more in the rubber-like polymer, and the reduced viscosity of the matrix portion is 0.77 dl / g. A rubber-modified polystyrene resin having a gel content of 27.1% by mass, a rubbery polymer content of 9.2% by mass, and a volume average particle size of 2.76 μm was used. The reduced viscosity, the mass% of the gel content of the rubbery polymer, the rubbery polymer content, and the volume average particle diameter of the rubbery polymer were measured by the following methods.

Measurement of reduced viscosity (ηsp / C): A mixed solvent of 15 ml of methyl ethyl ketone and 15 ml of acetone is added to 1 g of rubber-modified polystyrene resin, and dissolved by shaking at 25 ° C. for 2 hours. The supernatant is taken out, 500 ml of methanol is added to precipitate the resin component, and the insoluble component is filtered and dried. The resin component obtained by the same operation was dissolved in toluene to prepare a sample solution having a polymer concentration of 0.4% (mass / volume). The sample solution and pure toluene were measured at a constant temperature of 30 ° C. using a Ubbelohde viscometer, and the number of seconds during which the solution flowed was measured.
ηsp / C = (t1 / t0-1) / C
t0: Pure toluene flow down seconds
t1: Sample solution flow down seconds
C: Polymer concentration

Measurement of gel content: Rubber modified polystyrene resin was added to toluene at a ratio of 2.5% (mass / volume), dissolved by shaking at 25 ° C. for 2 hours, and then centrifuged (rotation speed: 10,000 to 14000 rpm, separation time 30). Min), the insoluble matter (gel content) was allowed to settle, and the supernatant was removed by decantation to obtain a gel. Next, this swollen gel was preliminarily dried at 100 ° C. for 2 hours, and then dried in a vacuum dryer at 120 ° C. for 1 hour. It cooled to normal temperature with the desiccator, weighed precisely, and computed with the following formula.
Gel fraction (%) = [(ba) / S] × 100
a: Mass of centrifugal settling tube
b: Dry gel + centrifuge tube mass
S: Sample resin mass

Measurement of rubbery polymer content: A rubber-modified polystyrene resin was dissolved in chloroform, a certain amount of iodine monochloride / carbon tetrachloride solution was added, and the mixture was allowed to stand for about 1 hour in a dark place. 50 ml of pure water was added, excess iodine monochloride was titrated with a 0.1N sodium thiosulfate / ethanol aqueous solution, and the amount of iodine monochloride added was calculated.

Measurement of volume average particle diameter of rubber-like polymer: A rubber-modified polystyrene resin was completely dissolved in dimethylformamide and measured with a laser diffraction particle size distribution apparatus.
Measuring device: Coulter laser diffraction particle analyzer LS-230

(B) The trade name REVODA110 manufactured by Kaisho Biological Materials Co., Ltd. was used for polylactic acid.

As the (C) brominated diphenylalkane compound, trade name SAYTEX 8010 (melting point: 350 ° C.) manufactured by Albemarle, which is (C-1) decabromodiphenylethane, was used.

(D) As a flame retardant aid, trade name AT-3CN manufactured by Suzuhiro Chemical Co., which is antimony trioxide, was used.

As a comparative example, instead of the (C) brominated diphenylalkane compound, the commercial name SAYTEX BT-93 (melting point: 456 ° C.) manufactured by Albemarle, which is (C-2) ethylenebistetrabromophthalimide, is used as the brominated phthalimide compound. It was.

As a comparative example, instead of (C) brominated diphenylalkane compound, (C-3) 2,4,6-tris (2,4,6-tribromophenoxy) -1,3,5- Trade name Piroguard SR245 (melting point: 232 ° C.) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., which is triazine, was used.

Next, a method for mixing the styrene-based flame retardant resin composition of the present invention will be described. (A) Rubber-modified styrene resin, (B) polylactic acid, (C) brominated diphenylalkane compound, and (D) flame retardant aid are blended in the amounts shown in the table, and all these components are combined into a Henschel mixer (Mitsui Mitsui). The mixture was preliminarily mixed with a chemical engineering company (FM20B), supplied to a twin-screw extruder (Toshiki Machine Co., Ltd., TEM26SS) to form a strand, cooled with water, and then led to a pelletizer to be pelletized. At this time, the cylinder temperature was 230 ° C. and the supply amount was 30 kg / hour. For Comparative Example 7 and Comparative Example 8, (C-2) ethylenebistetrabromophthalimide or (C-3) 2,4,6-tris (2,4,4) instead of (C) brominated diphenylalkane compound 6-Tribromophenoxy) -1,3,5-Triazine was mixed, and the same operation as in the other examples was performed.

Various measurements shown in Examples and Comparative Examples were performed by the following methods.

The test piece for the combustion test was molded at a cylinder temperature of 190 ° C. with an injection molding machine (Toshiba, IS80EP).

The flame retardancy was evaluated at a specimen thickness of 1.5 mm in accordance with the vertical burn test method of Subject No. 94 of US Underwriters Laboratories (UL). In addition, NG in a table | surface shows what does not satisfy any of V-2, V-1, and V-0.

The dripping acceleration at the time of ignition melting was evaluated by the time required for 1 g of the test piece to drop in the vertical subject test of UL Subject No. 94 (the value obtained by dividing the combustion time by the weight of the test piece melted and dropped). . It should be noted that measurement was not possible when there was no molten drop. In this invention, the case where the said dripping time of a styrene-type flame retardant resin composition was 22.0 second / g or less was set as the pass.

The results are shown in Tables 1 and 2 below.

From the examples in Table 1, it can be seen that the styrene-based flame retardant resin composition that achieves V-2 according to the UL94 standard of the present invention is excellent in flame retardancy and dripping acceleration during ignition melting.

However, it can be seen that the styrenic resin compositions obtained in the comparative examples in Table 2 that do not satisfy the provisions of the present invention cannot achieve V-2 in the UL94 standard, or do not exhibit dripping acceleration during ignition melting.

(B) If the addition amount of polylactic acid is less than the specified amount, the dripping accelerating property does not appear, so the flame retardancy does not reach V-2, and the flame retardant cannot be reduced (Comparative Example 1). (B) It is not preferable to add more polylactic acid than the specified amount because the flame retardancy does not reach V-2 (Comparative Example 2). Even if (C) the brominated diphenylalkane compound is added, if the amount added is less than the specified amount, the flame retardancy does not reach V-2 (Comparative Example 3), and conversely (C) brominated diphenylalkane. When the amount of the compound is more than the specified amount, V-0 is achieved, and the dripping acceleration is not expressed (Comparative Example 4). Even if (D) flame retardant aid is added, if the amount added is less than the prescribed amount, the flame retardancy does not reach V-2 (Comparative Example 5), conversely (D) flame retardant aid is prescribed. If it is added more than the amount, the flame retardancy does not reach V-2 because it exhibits a glowing behavior during combustion (Comparative Example 6). (C) When a brominated phthalimide compound is blended in place of the brominated diphenylalkane compound, V-2 is achieved but the dripping acceleration is not improved (Comparative Examples 7 and 8), and (C) of the brominated diphenylalkane compound If a brominated triazine compound is added instead, V-2 is achieved but the dripping acceleration is not improved (Comparative Examples 9 and 10).

The styrene flame retardant resin composition that achieves V-2 according to the UL94 standard of the present invention is excellent in dripping acceleration at the time of ignition and melting, so that the flame retardant can be reduced, and economically with a low environmental load. Since it is advantageous, it is advantageous to use it in OA equipment and home appliance parts.

Claims (4)

(A) 0.2 to 50.0 parts by mass of (B) polylactic acid, (C) 4 to 15 parts by mass of brominated diphenylalkane compound, and (D) flame retardant aid, relative to 100 parts by mass of styrene resin. A styrene-based flame retardant resin composition containing 0.3 to 3.0 parts by mass of an agent and achieving V-2 according to UL94 standards. (C) The styrenic flame retardant resin composition according to claim 1, wherein the brominated diphenylalkane compound is 1,2-bis (pentabromophenyl) ethane. (D) The flame retardant assistant is antimony trioxide, The styrene flame retardant resin composition according to claim 1 or 2. A molded article obtained by molding the styrene-based flame retardant resin composition according to any one of claims 1 to 3.