JP2018168284A - Thermoplastic resin composition - Google Patents

Abstract

To provide a thermoplastic resin composition that has excellent flame retardancy and, at the same time, has low flame strength at ignition with excellent flame spread resistance.SOLUTION: A thermoplastic resin composition contains (A) a thermoplastic resin, and is characterized in that: a gross calorific value at a cracking furnace temperature of 70-425°C, measured by ASTM D7309 Method A using a microscale combustion calorimeter, is at least 20% of a gross calorific value at a cracking furnace temperature of 200-600°C.SELECTED DRAWING: None

Description

  The present invention relates to a thermoplastic resin composition excellent in flame retardancy.

  Thermoplastic resins have been used in many products such as food packaging containers, miscellaneous goods, building materials, automobile materials, OA equipment, electronic parts, and home appliance casings, taking advantage of their excellent moldability.

  On the other hand, the thermoplastic resin is flammable, and there was concern about the safety of the product. Therefore, in order to eliminate this flammability, conventionally, flame retardant studies using various flame retardants have been conducted for the purpose of imparting flame retardancy to thermoplastic resins (see Patent Document 1).

  However, conventional flame retardancy studies have focused on the flammability for evaluating the combustion time, and the flame spreadability evaluated from the flame strength during ignition has been overlooked.

JP-A-8-73684

  An object of the present invention is to provide a thermoplastic resin composition that is excellent in flame retardancy and, at the same time, has low flame strength upon ignition and excellent flame spread resistance.

  The present invention includes (A) a thermoplastic resin, and a total calorific value at a cracking furnace temperature of 75 to 425 ° C. measured based on ASTM D7309 Method A using a microscale combustion calorimeter. It is a thermoplastic resin composition characterized by being 20% or more of the total calorific value at 200 to 600 ° C.

In this invention, the following structures are included as a preferable aspect.
The thermoplastic resin (A) is at least one of a rubber-modified styrene resin and a polyolefin resin, and in particular, the content of 4-tert-butylcatechol contained in the rubber-modified styrene resin is 6 mg / kg or less. Be.
Furthermore, it contains (B) a halogen-based flame retardant, particularly 3 to 25 parts by mass of the (B) halogen-based flame retardant with respect to 100 parts by mass of the (A) thermoplastic resin, and further , (C) containing a flame retardant aid, in particular 0.1 to 7 parts by mass of the flame retardant aid (C) with respect to 100 parts by mass of the thermoplastic resin (A).

  According to the present invention, a thermoplastic resin composition excellent in flame retardancy and fire spread resistance is defined by defining the ratio of the total calorific value in a specific cracking furnace temperature range measured using a microscale combustion calorimeter. A thing is obtained. Therefore, it is advantageous to use it in building materials, automobile materials, OA equipment, home appliance housings and the like that require flame retardancy and fire spread resistance.

It is a figure which shows an example of the heat dissipation rate characteristic curve obtained by the measurement based on ASTM D7309.

  As a result of various studies on the flame retardancy and fire spread resistance of the thermoplastic resin composition, the present inventors measured using a micro-scale combustion calorimeter (MCC) based on ASTM D7309 method A. Thus, the present invention has been achieved by finding that the ratio of the total calorific value in a specific cracking furnace temperature range can be used as an indicator of flame retardancy and fire spread resistance.

  MCC is an apparatus for evaluating the combustion characteristics of combustible materials based on ASTM D7309, and has a decomposition furnace and a combustion furnace in the apparatus. In ASTM D7309, a sample is placed in an MCC cracking furnace, and the cracking furnace is heated at an arbitrary speed while flowing a mixed gas of nitrogen or nitrogen and oxygen into the cracking furnace, and the cracked gas generated therefrom is burned. It introduce | transduces into a furnace, burns cracked gas in presence of nitrogen and oxygen, and calculates a heat release rate (Heat Release Rate, HRR) from the amount of oxygen consumed. In such a method, the form of the sample is not limited, the reproducibility is good, and the combustion characteristics can be quantitatively shown.

In the present invention, based on ASTM D7309 Method A, the heat release rate (HRR) [W / g] per 1 g of sample is measured over time under the following conditions. Since the temperature of the cracking furnace is increased at a constant rate, the temperature of the cracking furnace corresponding to the measurement time is plotted on the horizontal axis, and the heat release rate obtained from the amount of oxygen consumed measured at the time is plotted on the vertical axis. A heat dissipation characteristic curve as shown is obtained. In addition, FIG. 1 is an example and is not limited to the heat dissipation rate characteristic curve according to the present invention.
Sample mass: 3.0mg
Decomposition furnace heating rate: 1.0 ° C / sec
Decomposition furnace temperature: 850 ° C
Combustion furnace temperature: 900 ° C (constant)
Decomposition furnace atmosphere: Nitrogen (anaerobic condition) (80 ml / min)
Combustion furnace atmosphere: oxygen / nitrogen mixed gas (oxygen 20 ml / min, nitrogen 80 ml / min)

  In the thermoplastic resin composition of the present invention, the ratio of the total calorific value at the cracking furnace temperature of 75 to 425 ° C. with respect to the total calorific value at the cracking furnace temperature of 200 to 600 ° C. is 20% or more. The total calorific value is the sum of values obtained by multiplying the heat release rate at each measurement point in the corresponding temperature range by the measurement interval (time). In the curve of FIG. 1, the horizontal axis represents the cracking furnace temperature, but since the cracking furnace temperature is raised at a constant rate, the horizontal axis corresponds to the time from the start of the temperature raising. Therefore, in the curve with time on the horizontal axis, the integrated value of the heat release rate during the time when the cracking furnace temperature reached 200 ° C. and 600 ° C. is the total calorific value between the cracking furnace temperatures 200-600 ° C. The integral value of the heat release rate during the time when the temperature reaches 75 ° C. and 425 ° C. is the total calorific value between the cracking furnace temperatures of 75 to 425 ° C.

  In the present invention, if the ratio of the total calorific value at the cracking furnace temperature of 75-425 ° C. with respect to the total calorific value between the cracking furnace temperature of 200-600 ° C. is a thermoplastic resin composition having a heat dissipation characteristic of 20% or more, Excellent flame retardancy and fire spread resistance are obtained.

  The thermoplastic resin (A) used in the present invention is not particularly limited as long as it is a polymer having thermoplasticity. Polystyrene (GPPS), acrylonitrile-styrene copolymer (AS resin), methyl methacrylate-styrene General-purpose styrene resins such as copolymer (MS resin), maleic anhydride-styrene copolymer, acrylic acid (or methacrylic acid) ester / styrene copolymer; high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene Copolymer (ABS resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-ethylenepropylene-styrene copolymer (AES resin), methyl methacrylate-butadiene-styrene copolymer (MBS resin), etc. Rubber-modified styrenic resin; poly Α-olefin polymers and copolymers of at least one of α-olefins having 2 to 10 carbon atoms, such as ethylene (PE), polypropylene (PP), and ethylene / propylene copolymers, and chlorinated polyethylenes thereof Olefin resins such as modified polymers and modified copolymers, cyclic olefin copolymers, etc .; ethylene copolymers such as ionomers, ethylene / vinyl acetate copolymers, ethylene / vinyl alcohol copolymers; polyvinyl chloride Resin (PVC), ethylene-vinyl chloride polymer, polyvinyl chloride resin such as polyvinylidene chloride (PVDC); heavy weight using one or more of acrylic acid (or methacrylic acid) ester such as polymethyl methacrylate (PMMA) Acrylic resins such as coalesces and copolymers; polyamide 6, polyamide 6,6, polyamide 6,1 Polyamide resins (PA) such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyester resins such as polyethylene naphthalate; polyacetal (POM); polycarbonate (PC); polyarylate (PAR); PPE); polyphenylene sulfide (PPS); fluorine resin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF); liquid crystal polymer; polyimide resin (PI), polyamideimide (PAI), polyetherimide (PEI), etc. Imide resins; ketone resins such as polyether ketone and polyether ether ketone (PEEK); sulfone resins such as polysulfone (PSU) and polyether sulfone (PES); urethane Fat (PU); polyvinyl acetate (PVAc); polyethylene oxide (PEO), polyvinyl alcohol (PVA); polyvinyl ethers, polyvinyl butyral, phenoxy resin, polylactic acid resin (PLA) and the like. These can be used alone or in combination of two or more. Of these, general-purpose styrene resins, rubber-modified styrene resins, olefin resins, acrylic resins, vinyl chloride resins, polycarbonate resins, polyester resins, polyamide resins, and polyphenylene ether are preferable, and rubber modified resins are particularly preferable. Styrenic resin, olefinic resin, acrylic resin, polycarbonate resin, polyester resin, and polyphenylene ether are preferable, and rubber-modified styrene resin and polyolefin resin such as polypropylene are more preferable.

  The styrene resin is obtained by polymerizing an aromatic vinyl compound monomer, and a styrene resin that has been rubber-modified by adding a rubbery polymer is referred to as a rubber-modified styrene resin. 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, styrene monomers such as acrylonitrile, acrylic acid, methacrylic acid, acrylic acid (or methacrylic acid) ester, maleic anhydride, etc. that are copolymerizable with these aromatic vinyl compound monomers The body may be of a level that does not impair the performance of the thermoplastic 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.

  The rubber-like polymer used for the rubber-modified styrene resin includes polybutadiene, styrene-butadiene random or block copolymer, polyisoprene, polychloroprene, styrene-isoprene random, block or graft copolymer, and ethylene-propylene rubber. , Ethylene-propylene-diene rubber, and the like, and in particular, random, block or graft copolymers of polybutadiene and styrene-butadiene are preferable. These may be partially hydrogenated, or may be used alone or in combination of two or more.

  The content of the rubbery polymer in the rubber-modified styrenic resin is preferably 3 to 15% by mass. When the content of the rubbery polymer is 3 to 15% by mass, a thermoplastic resin composition having an excellent balance between impact resistance and heat resistance can be obtained.

  The volume average particle diameter of the rubber-like polymer in the rubber-modified styrenic resin is preferably 0.1 to 5.0 μm mass%, particularly preferably 1.0 to 4.0 μm mass%. When the volume average particle diameter of the rubbery polymer is 0.1 to 5.0 μm, a significant impact resistance improving effect can be obtained.

  The content of 4-tert-butylcatechol (TBC) contained in the rubber-modified styrene resin is preferably 6 mg / kg or less. More preferably, it is 0.1-5 mg / kg. TBC is a polymerization initiator, and if the content of TBC is 6 mg / kg or less, the flame retardancy stability is increased, which is preferable.

  As a structure of the thermoplastic resin composition of this invention, it is preferable to contain (B) halogenated flame retardant other than (A) thermoplastic resin.

  Examples of the halogen-based flame retardant (B) used in the present invention include halogenated diphenyl ether compounds, halogenated diphenylalkane compounds, halogenated phthalimide compounds, tris (polyhalogenphenoxy) triazine compounds, halogenated bisphenol A polymers, halogenated compounds. Examples thereof include a styrene / butadiene block copolymer, a halogenated styrene / butadiene random copolymer, and a halogenated styrene / butadiene graft copolymer. Preferred are halogenated diphenylalkane compounds, halogenated phthalimide compounds, and tris (polyhalogenphenoxy) triazine compounds.

  The halogenated diphenylalkane compound is a compound represented by the following formula [1].

In the above formula [1], 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 halogen atom of an integer of 1 to 5, and X ₁ + X ₂ Represents ≧ 2.

  Examples of the halogenated diphenylalkane compound include diphenylmethane, 1,2-diphenylethane, 1,3-diphenylpropane, 1,6-diphenylhexane, and the like, trihalogen-substituted products, tetrahalogen-substituted products, and pentahalogen-substituted products. , Hexahalogen-substituted, heptahalogen-substituted, octahalogen-substituted, nonahalogen-substituted, and decahalogen-substituted. Preferred is decahalogen diphenylethane, and particularly preferred is decabromodiphenylethane.

  The halogenated phthalimide compound is a compound represented by the following formula [2].

In the above formula [2], R is an alkylene group having a structure of C _n H _2n (n is an integer of 0 to 6), X ₁ and X ₂ are each independently a halogen atom of an integer of 1 to 4, and X ₁ + X ₂ Represents ≧ 2.

  Examples of halogenated phthalimide compounds include methylene-bis-phthalimide, ethylene-bis-phthalimide, propylene-bis-phthalimide, butylene-bis-phthalimide, pentylene-bis-phthalimide, hexylene-bis-phthalimide, and the like, trihalogens Examples include substituted, tetrahalogen-substituted, pentahalogen-substituted, hexahalogen-substituted, heptahalogen-substituted, and octahalogen-substituted. Preferred is ethylene-bis-tetrahalogen phthalimide, and particularly preferred is ethylene-bis-tetrabromophthalimide.

  The tris (polyhalogenphenoxy) triazine compound is a compound represented by the following formula [3].

In the above formula [3], X is independently an integer of 1 to 3 halogen atoms, and X ₁ + X ₂ + X ₃ ≧ 3.

  Examples of the tris (polyhalogenphenoxy) triazine compound include trihalogen trisubstituted, tetrahalogen substituted, pentahalogen substituted, hexahalogen substituted, heptahalogen substituted, octahalogen substituted, nonahalogen substituted triphenoxytriazine. It is done. Tris (trihalogenphenoxy) triazine is preferable, and tris (tribromophenoxy) triazine is particularly preferable.

  In this invention, the addition amount of (B) halogenated flame retardant is 3-25 mass parts with respect to 100 mass parts of (A) thermoplastic resins, Preferably 5-20 mass parts is preferable.

  In the present invention, it is preferable to further contain a flame retardant aid (C). The (C) flame retardant aid functions to further enhance the flame retardant effect of the (B) halogen flame retardant, such as antimony oxide, antimony trioxide, antimony tetroxide, antimony pentoxide, sodium antimonate, etc. Zinc borate, barium metaborate, anhydrous zinc borate, anhydrous boric acid, etc. as boron compounds, stannic oxide, zinc stannate, zinc hydroxystannate, etc. as tin compounds, molybdenum oxide, molybdenum as molybdenum compounds Examples of the ammonium compound include zirconium oxide and zirconium hydroxide as the zirconium compound, and zinc sulfide as the zinc compound. Among them, it is particularly preferable to use antimony trioxide.

  In this invention, 0.1-7 mass parts is preferable with respect to 100 mass parts of (A) thermoplastic resins, and, as for the addition amount of (C) flame retardant adjuvant, 0.5-6 mass parts is especially preferable. The effect of improving the flame retardancy of the thermoplastic resin composition is obtained at 0.1 part by mass or more, and a molded article with a good appearance is obtained when it is 7 parts by mass or less.

  In addition, the thermoplastic resin composition of the present invention has various additives such as dyes, pigments, anti-coloring agents, lubricants, antioxidants, anti-aging agents, light stabilizers, antistatic agents to the extent that the effects of the present invention are obtained. Known additives such as additives, fillers and compatibilizers, and modifiers such as colorants such as titanium oxide and carbon black can be added. These addition methods are not particularly limited, and are known methods, for example, (A) the thermoplastic resin to be used before the start of polymerization, during the polymerization in the middle of polymerization, or after the completion of polymerization, and (B) When the halogen-based flame retardant or (C) flame retardant aid is blended, it can also be added in an extruder or a molding machine.

  A known mixing technique can be applied to the method for mixing the thermoplastic resin composition of the present invention. For example, a uniform resin composition can be obtained by 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. There are no particular restrictions on the melt kneader. 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.

  Examples of a molding method for obtaining a molded product from the resin composition of the present invention include injection molding.

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

(A) Thermoplastic resin A-1: Rubber-modified impact-resistant polystyrene resin (the rubber-like polymer is polybutadiene rubber, the rubber-like polymer content in the matrix portion is 9.0% by mass, and the volume-average particle of the rubber-like polymer. (Diameter 3.0μm, TBC content 2.0mg / kg in the matrix part)
A-2: Polypropylene resin ("Novatec PP MA1B" manufactured by Nippon Polypro Co., Ltd.)

<Measurement of rubbery polymer content>
Dissolve the sample in chloroform, add a certain amount of iodine monochloride / carbon tetrachloride solution, leave it in the dark for about 1 hour, add 15% by weight potassium iodide solution and 50 ml of pure water, and add excess iodine monochloride. The solution was titrated with 0.1N sodium thiosulfate / ethanol aqueous solution and calculated from the amount of added iodine monochloride.

<Measurement of volume average particle diameter of rubbery polymer>
The sample was dissolved in dimethylformamide and measured with a laser diffraction particle size distribution apparatus (laser diffraction particle “Analyzer LS-230” manufactured by Beckman Coulter, Inc.).

<Measurement of TBC content>
Dissolve 2 g of the sample in 100 ml of tetrahydrofuran (THF), remove the rubber-like dispersed particles with a centrifuge (“H-2000B” (rotor: H) manufactured by Kokusan Co., Ltd.), collect 10 ml of the supernatant, 200 μl of N, O-bis (trimethylsilyl) trifluoroacetamide was added, and the TBC content in the sample was measured with a gas chromatograph / mass spectrometer (GC / MS).
Apparatus: “HP7890 / HP5974” manufactured by Agilent Technologies
Column: “DB-5MS” manufactured by Agilent Technologies
Oven: 50 ° C
Inlet: 300 ° C
Carrier: helium, 1 ml / min
Detector: Mass spectrometer

(B) Halogen-based flame retardant Decabromodiphenylethane (“SAYTEX 8010” manufactured by Albemarle)

(C) Flame retardant auxiliary antimony trioxide ("AT-3CN" manufactured by Suzuhiro Chemical Co., Ltd.)

  The above (A) thermoplastic resin, (B) halogen-based flame retardant and (C) flame retardant aid are blended in parts by mass shown in Table 1, and all these components are combined into a Henschel mixer ("FM20B" manufactured by Nippon Coke Industries, Ltd.). ) And then fed into a twin screw extruder (“TEM26SS” manufactured by Toshiba Machine Co., Ltd.) to form a strand, which was cooled to water and led to a pelletizer to be pelletized. At this time, the cylinder temperature was 230 ° C. and the supply amount was 30 kg / hour.

  Using the obtained pellet, MCC ("MCC-3" manufactured by DETAK) was used, and based on ASTM D7309 Method A, the heat dissipation rate [W / g] was measured under the above-described conditions, and the cracking furnace temperature was 200 to 600. The total calorific value [kJ / g] at 0 ° C. and the total calorific value [kJ / g] at the cracking furnace temperature of 75 to 425 ° C. are obtained respectively, and the total calorific value at the cracking furnace temperature of 200 to 600 ° C. and the cracking furnace temperature The total calorific value at 75 to 425 ° C. was determined, and the ratio of the total calorific value at the cracking furnace temperature 75 to 425 ° C. to the total calorific value at the cracking furnace temperature 200 to 600 ° C. was calculated. Moreover, flame retardance was evaluated by the method shown below using the obtained pellet. The results are shown in Table 1.

<Fire spread resistance>
Of the heat release rate measured based on ASTM D7309 Method A using the MCC, the fire spread resistance was evaluated by the heat release rate (maximum heat release rate) when the maximum reached between the decomposition furnace temperatures of 200 to 600 ° C. According to the present inventors, it has been found that the fire spread resistance is insufficient when the maximum heat dissipation rate is 500 W / g or more. Therefore, in this invention, the case where the maximum heat dissipation rate was less than 500 W / g was set as the pass.

<Flame retardance>
Flame retardancy was evaluated by the total calorific value at a cracking furnace temperature of 200 to 600 ° C. measured based on ASTM D7309 Method A using the MCC. According to the present inventor, it has been found that when the total calorific value is 39.0 J / g or more, the flame retardancy is insufficient. Therefore, in the present invention, the total calorific value is less than 39.0 J / g.

<UL94 flame retardancy>
A test piece for combustion having a length of 127 mm, a width of 12.7 mm, and a thickness of 2.5 mm was molded using an injection molding machine (“J100E-P” manufactured by Nippon Steel Works). At this time, the cylinder temperature of the injection molding machine was 220 ° C., and the mold temperature was 45 ° C. Using this test piece, the combustibility was evaluated in accordance with the vertical combustion test method of UL94. When this test method did not satisfy V-2, it was determined as NG.

  From Table 1, in the example in which the ratio of the total calorific value at the cracking furnace temperature of 75 to 425 ° C. with respect to the total calorific value at the cracking furnace temperature of 200 to 600 ° C. is 20% or more, the maximum heat dissipation rate is less than 500 W / g. The total calorific value was less than 39.0 kJ / g, high flame retardancy and fire spread resistance were shown, and high flame retardancy was also shown in the UL94 evaluation. On the other hand, it was found that the comparative example was inferior in flame retardancy at a maximum heat dissipation rate of 500 W / g or more, and inferior in flame retardance in UL94 evaluation.

The present invention contains (A) a thermoplastic resin and (B) a halogen flame retardant ,
The (A) thermoplastic resin is at least one of a rubber-modified styrene resin and a polyolefin resin,
3 to 25 parts by mass of the (B) halogen flame retardant with respect to 100 parts by mass of the (A) thermoplastic resin,
Measured based on ASTM D7309 Method A using a micro-scale combustion calorimeter, the total calorific value at a cracking furnace temperature of 75-425 ° C is 20% or more of the total calorific value at a cracking furnace temperature of 200-600 ° C This is a thermoplastic resin composition.

In this invention, the following structures are included as a preferable aspect.
The content of 4-tert-butylcatechol included before Symbol rubber-modified styrene resin is less than 6 mg / kg.
Furthermore , it contains ( C) a flame retardant aid, in particular 0.1 to 7 parts by mass of the (C) flame retardant aid with respect to 100 parts by mass of the (A) thermoplastic resin.

Claims (7)

  (A) The total calorific value at a cracking furnace temperature of 75 to 425 ° C. measured according to ASTM D7309 Method A containing a thermoplastic resin and using a microscale combustion calorimeter is 200 to 600 ° C. A thermoplastic resin composition characterized by being 20% or more of the total calorific value in   The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin (A) is at least one of a rubber-modified styrene resin and a polyolefin resin.   The thermoplastic resin composition according to claim 2, wherein the content of 4-tert-butylcatechol contained in the rubber-modified styrenic resin is 6 mg / kg or less.   The thermoplastic resin composition according to any one of claims 1 to 3, further comprising (B) a halogen-based flame retardant.   5. The thermoplastic resin composition according to claim 4, comprising 3 to 25 parts by mass of the (B) halogen flame retardant with respect to 100 parts by mass of the (A) thermoplastic resin.   The thermoplastic resin composition according to claim 4 or 5, further comprising (C) a flame retardant aid.   The resin composition according to claim 6, wherein 0.1 to 7 parts by mass of the flame retardant aid (C) is contained with respect to 100 parts by mass of the (A) thermoplastic resin.

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