JP4451621B2 - Flame retardant thermoplastic polyurethane composition and molded article - Google Patents

Description

  The present invention relates to a flame retardant thermoplastic polyurethane composition and a molded body obtained from the composition, and more particularly, a flame retardant which is easy to be molded by extrusion molding and does not contain halogen elements such as bromine and chlorine. The present invention relates to a heat-resistant thermoplastic polyurethane composition and a molded article obtained from the composition.

  Thermoplastic polyurethane exhibits flexibility and extremely good wear resistance, and is useful for OA equipment parts, household appliance parts, automobile interior materials, house interior materials, etc. It is flammable. In order to make this flame-retardant, generally, a halogen-based flame retardant is blended. However, the halogen-based flame retardant can impart high flame retardancy with a small amount of blending, but has a disadvantage that harmful gases are generated during combustion.

  On the other hand, non-halogen flame retardants (non-halogen flame retardants) include nitrogen flame retardants such as melamine and melamine cyanurate, phosphorus flame retardants such as ammonium polyphosphate, triphenyl phosphate and melamine polyphosphate, and hydroxylation. There are inorganic flame retardants such as magnesium and aluminum hydroxide. Among them, phosphorus flame retardants are effective with a small amount. However, when a flame retardant is added to a thermoplastic polyurethane, flame retardancy can be imparted, but the molecular chain of the thermoplastic polyurethane molecule is cleaved by the phosphorus flame retardant, resulting in a decrease in molecular weight and a significant decrease in melt viscosity. In addition, it has the disadvantage of causing a significant decrease in mechanical properties.

Under such circumstances, a flame retardant polyurethane composition comprising a thermoplastic polyurethane, a powder obtained by microencapsulating ammonium polyphosphate with a melamine formaldehyde resin or an epoxy resin, and an inorganic flame retardant (See Patent Document 1). This is due to the decrease in physical properties caused by the direct blending of ammonium polyphosphate with thermoplastic polyurethane, and by avoiding contact between thermoplastic polyurethane and ammonium polyphosphate by microencapsulating ammonium polyphosphate, tensile properties, especially tensile strength It is intended to prevent the decrease of However, microencapsulation of ammonium polyphosphate has a problem that the cost is increased and the effect of imparting flame retardancy is lowered.
JP-A-5-9376

  The present invention has been made in view of such circumstances, a flame-retardant thermoplastic polyurethane composition from which a molded article having good moldability and a good appearance can be obtained, and a molding comprising the composition. The purpose is to provide a body.

  As a result of intensive studies, the present inventors compounded a thermoplastic polyurethane (A) with a phosphorus-based flame retardant (B) and an epoxy compound (C) having two or more epoxy groups in the molecule at a specific ratio. As a result, the inventors have found that the above object can be achieved and have reached the present invention.

That is, the present invention
(1) A halogen-free composition comprising a thermoplastic polyurethane (A), a phosphorus-based flame retardant (B), and an epoxy compound (C) having two or more epoxy groups in the molecule, the composition The blending ratio of the thermoplastic polyurethane (A) and the phosphorus-based flame retardant (B) is (A) :( B) = 92 to 45: 8 to 55 by weight ratio, and (A) and (B) The flame-retardant heat for extrusion molding, wherein 0.1 to 30 parts by weight of an epoxy compound (C) having two or more epoxy groups in the molecule is blended with respect to 100 parts by weight of the total amount of The present invention relates to a plastic polyurethane composition.

(2) A composition obtained by further blending a conductive agent (D) with the composition according to (1), wherein the total amount of the thermoplastic polyurethane (A) and the phosphorus-based flame retardant (B) is 100 wt. The present invention relates to a flame retardant thermoplastic polyurethane composition for extrusion molding , characterized in that 0.05 to 25 parts by weight of the conductive agent (D) is blended with respect to parts.

(3) The conductive agent (D) is carbon black or grafted carbon black, and relates to the flame-retardant thermoplastic polyurethane composition for extrusion molding according to (2).

(4) The flame retardant thermoplastic polyurethane composition for extrusion molding according to (2), wherein the conductive agent (D) is a polymer having a polyalkylene oxide chain in the molecule.

(5) The present invention relates to an extruded product comprising the flame-retardant thermoplastic polyurethane composition according to any one of (1) to (4).

(6) A molded article of a multi-layer structure, relates them at least one layer (1) to (4) extrudates, characterized in that it consists of a flame retardant thermoplastic polyurethane composition according to any one of is there.

(7) The present invention relates to the extruded product according to (5) or (6), which is a seamless belt.

  In the flame-retardant thermoplastic polyurethane composition of the present invention, even when the molecular chain of the thermoplastic polyurethane (A) is cleaved by the phosphorus-based flame retardant (B), the molecules of the thermoplastic polyurethane (A) having a low molecular weight are bonded to each other. Further, since they are bonded again via the epoxy compound (C) having two or more epoxy groups in the molecule, the flow characteristics at the time of melting are good, and the moldability is excellent. And the molded object which consists of such a composition shows the favorable external appearance, and there exists an advantage that it is the thing excellent also in the flame retardance.

  The flame retardant thermoplastic polyurethane composition of the present invention comprises a halogen comprising a thermoplastic polyurethane (A), a phosphorus flame retardant (B), and an epoxy compound (C) having two or more epoxy groups in the molecule. It is a composition which does not contain, Comprising: The mixing ratio of the thermoplastic polyurethane (A) in this composition and a phosphorus flame retardant (B) is a weight ratio (A) :( B) = 92-45: 8-55 And 0.1 to 30 parts by weight of an epoxy compound (C) having two or more epoxy groups in the molecule with respect to 100 parts by weight of the total amount of (A) and (B). (Hereinafter, the epoxy compound (C) having two or more epoxy groups in the molecule may be simply referred to as an epoxy compound (C)).

  As the thermoplastic polyurethane (A) used in the present invention, a commercially available thermoplastic polyurethane can be used. For example, hexamethylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, toluylene diisocyanate, etc. as diisocyanates, polytetramethylene glycol, polyethylene glycol, and hydroxyl groups at both ends as long chain diols Thermoplastic polyurethane using 1,4-butanediol, cyclohexanediol, ethylene glycol or the like as the short-chain diol, such as aliphatic polyester.

  The phosphorus flame retardant (B) used in the present invention is not particularly limited as long as it is a phosphorus compound exhibiting a flame retardant effect. For example, inorganic phosphate compounds such as ammonium polyphosphate, triphenyl phosphate And phosphate ester compounds such as triethyl phosphate, melamine polyphosphate, and the like. Moreover, such phosphorus flame retardant can also be used individually by 1 type or in mixture of 2 or more types by arbitrary mixing ratios.

  Furthermore, in the present invention, as the phosphorus flame retardant (B), there is little decrease in the molecular weight of the thermoplastic polyurethane due to blending, and the acid value can be reduced because the blending amount of the epoxy compound (C) described later can be kept small. It is preferable to use one that is 2 eq / kg or less.

  On the other hand, the epoxy compound (C) having two or more epoxy groups in the molecule is not particularly limited as long as it is a compound having two or more epoxy groups in the molecule. For example, a co-polymer of glycidyl methacrylate and methyl methacrylate. Glycidyl ester type epoxy resin such as polymer, bisphenol A type epoxy resin such as bisphenol A-diglycidyl, cyclic aliphatic epoxy resin, copolymer of glycidyl methacrylate and ethylene, copolymer of glycidyl methacrylate and styrene, epoxidation Examples thereof include styrene-ethylene / butylene-styrene block copolymers and epoxidized styrene-ethylene / isoprene-styrene block copolymers. Moreover, these derivatives can also be used. Furthermore, such an epoxy compound can be used alone or in admixture of two or more at any mixing ratio.

  In particular, in the present invention, the epoxy compound (C) is preferably an epoxy compound having an epoxy equivalent of 1500 g / eq or less because the melt viscosity can be adjusted with a small amount.

  In the present invention, the mixing ratio of the thermoplastic polyurethane (A) and the phosphorus-based flame retardant (B) is (A) :( B) = 92 to 45: 8 to 55, more preferably (A): (B) = 93-50: 7-50. When the blending ratio of the phosphorus-based flame retardant (B) in the total 100 parts by weight of the thermoplastic polyurethane (A) and the phosphorus-based flame retardant (B) exceeds 55 parts by weight, continuous molding processing becomes difficult. Causes a reduction in strength of the resulting molded article. Conversely, if the blending ratio of the phosphorus-based flame retardant (B) is less than 8 parts by weight, the effect of improving flame retardancy becomes insufficient, which is not preferable.

  In the present invention, the blending ratio of the epoxy compound (C) in the composition is 100 parts by weight of the total amount of the thermoplastic polyurethane resin (A) and the phosphorus flame retardant (B) in the composition. It is 0.1-30 weight part with respect to it, Preferably it is 0.5-25 weight part. By blending the epoxy compound (C) at this ratio, when the thermoplastic polyurethane (A) and the phosphorus-based flame retardant (B) are kneaded with heat, the molecular chains are cut to reduce the molecular weight of the thermoplastic polyurethane molecules. Can be recombined via the epoxy compound (C). As a result, a decrease in the melt viscosity of the composition during the molding process can be avoided, the molding processability can be improved, and a molded article having a good appearance can be obtained.

  When the content of the epoxy compound (C) with respect to 100 parts by weight of the total amount of the thermoplastic polyurethane (A) and the phosphorus-based flame retardant (B) exceeds 30 parts by weight, the epoxy compound is easily flammable. The oxygen index is lowered and the flame retardancy is insufficient. In addition, when the content of the epoxy compound (C) is less than 0.1 parts by weight with respect to 100 parts by weight of the total amount of the thermoplastic polyurethane (A) and the phosphorus-based flame retardant (B), the epoxy compound (C) component This is not preferable because the effect of blending, that is, the effect of preventing the decrease in the melt viscosity of the composition at the time of molding processing by recombining the thermoplastic polyurethane molecules having reduced molecular weights again.

The present invention also provides a flame retardant thermoplastic polyurethane composition in which a conductive agent (D) is further blended with the above composition for the purpose of application to electronic equipment such as electrophotography.
In this case, the compounding quantity of the electrically conductive agent (D) in a composition shall be 0.05-25 weight part with respect to 100 weight part of total amounts with a thermoplastic polyurethane (A) and a phosphorus flame retardant (B). . If it is less than the above range, semiconductivity cannot be imparted to the composition. If it exceeds the above range, not only the extrusion processability is deteriorated, but also the strength of the molded product is lowered.

  Examples of the conductive agent (D) include an electron conductive material, and examples thereof include carbon black, grafted carbon black, metal oxide, and metal powder. Among these electron conductive materials, it is preferable that carbon black is included as an essential component because the resistance of the composition is reduced with a small amount of the compound. Examples of carbon black include acetylene black, furnace black, and channel black. Among them, acetylene black and ketjen black, which is a kind of furnace black, are preferable from the viewpoint that semiconductivity can be imparted with a small amount. In addition, in order to reduce the variation in resistance value of the molded product formed from the composition, it is also possible to use surface-treated carbon black or grafted carbon black (for example, see JP-A-11-29678). it can.

  Examples of the conductive agent (D) include an ion conductive material. Specifically, polymers having a polyalkylene oxide chain in the molecule such as polyethylene oxide, a copolymer of ethylene oxide and propylene oxide, a copolymer of ethylene oxide and epichlorohydrin, polyether ester, polyether ester amide, etc. Is mentioned. In addition, a polymer containing an ionic group such as a quaternary ammonium salt, a sulfonate, or a carboxylate in the molecule, so-called ionomer can be used. Among these, a polymer having a polyalkylene oxide chain in the molecule is preferable. Further, when a polymer having a polyalkylene oxide chain in the molecule is used as the conductive agent (D), it is preferable to use this in combination with an ionic electrolyte. By using an ionic electrolyte in combination, not only can the amount of the polymer having a polyalkylene oxide chain in the molecule be suppressed, but also the electrical resistance varies due to changes in temperature and humidity, so-called environmental dependence of electrical resistance. Get smaller. Examples of the ionic electrolyte include thiocyanates, phosphates, sulfates, halides, and halogen acid chloric acids of alkali metals or alkaline earth metals. Among them, potassium thiocyanate and thiocyanate are particularly preferable. Sodium, lithium thiocyanate, potassium perchlorate, sodium perchlorate, and lithium perchlorate are particularly preferred because they can lower the electrical resistance with a small amount.

  A flame retardant other than the phosphorus flame retardant (B) can be added to the flame retardant thermoplastic polyurethane composition of the present invention as long as the effect of the invention is maintained. Examples thereof include inorganic hydroxides such as aluminum hydroxide and magnesium hydroxide, borates such as zinc borate and ammonium borate, and silicon compounds such as silicon dioxide.

  Furthermore, the flame retardant thermoplastic polyurethane composition of the present invention has a known stabilizer, ultraviolet absorber, antioxidant, lubricant, processing aid, as long as the effects of the invention are maintained as necessary. It is of course possible to blend other ingredients such as various compounding agents such as foaming agents and fillers and colorants such as dyes and pigments.

The flame-retardant thermoplastic polyurethane composition of the present invention has a apparent viscosity (η _ap ) of 1900 to 50000 poise at a measurement temperature of 200 ° C. and a test pressure of 9.8 MPa in accordance with JIS K7210 Annex C (reference). It is particularly preferable from the viewpoint of extrusion moldability.

  The flame-retardant thermoplastic polyurethane composition of the present invention includes, for example, the above-described thermoplastic polyurethane (A), phosphorus flame retardant (B), epoxy compound (C), thermoplastic polyurethane (A), phosphorus flame retardant. (B), an epoxy compound (C), and a conductive agent (D) can be produced by heating and kneading at 120 to 240 ° C, preferably 150 to 220 ° C. The apparatus used for heat kneading is not particularly limited as long as it can be heat kneaded under the above-mentioned conditions. For example, a heat kneading apparatus such as a blender, kneader, mixing roll, Banbury mixer, uniaxial or biaxial extruder, etc. Preferably, a twin-screw extruder capable of controlling the cooling of the composition temperature is used.

  The flame retardant thermoplastic polyurethane composition of the present invention thus obtained has an excellent flame retardancy with an oxygen index value specified by JIS K 7201 exceeding 26.0, and a normal extruder and Even if it molds using a metal mold | die, since it does not draw down, the wrinkle which becomes a molding defect does not generate | occur | produce in a molded article, and the various molded object which has the favorable external appearance which is not torn by the fall of melt viscosity is obtained.

  The flame-retardant thermoplastic polyurethane composition of the present invention can be formed into various molded products. Extrusion inflation molding is also possible, and it is also possible to form a seamless seamless belt shape. Furthermore, the molded product obtained from the flame retardant thermoplastic polyurethane composition of the present invention is not limited to a single layer structure, for example, polyolefins such as polyethylene and polypropylene, polyesters such as polybutylene terephthalate and polyethylene terephthalate, polystyrene, polyamide and polycarbonate. A multilayer structure with polyvinylidene fluoride or the like can also be used.

  The field of use of the molded product obtained by using the flame-retardant thermoplastic polyurethane composition of the present invention is not particularly limited, such as OA equipment parts, household appliance parts, automobile interior materials, house interior materials, etc. It can be used in many fields where thermoplastic resins are conventionally used. Among these, the seamless belt formed seamlessly into a seamless belt is most utilized in the flame-retardant thermoplastic polyurethane composition of the present invention, which is capable of extrusion blow molding. In particular, the seamless belt made of the flame retardant thermoplastic polyurethane composition of the present invention, which is blended with a conductive agent and imparts semiconductivity, can form images by electrophotography or electrostatic printing such as copying machines, facsimiles, and printers. It is suitably used as a sheet material conveying belt, a transfer belt, an intermediate transfer belt, a fixing belt, a developing belt, a photoreceptor substrate belt, etc. in an image forming apparatus to be performed. In addition, a conductive roll in which a similar seamless belt is covered with a metal or non-metallic core rod is also suitably used as a charging roll, a toner supply roll, a developing roll, and a transfer roll.

  EXAMPLES Next, an Example demonstrates this invention in detail. In addition, the evaluation method of the raw material and composition used in the following examples is as follows. The acid value of the phosphorus flame retardant was determined by titrating the phosphorus flame retardant with a 0.1N potassium hydroxide aqueous solution.

<Thermoplastic polyurethane (A)>
A-1: Elastollan C85A11FG, ester polyurethane, melt viscosity 14260 poise, manufactured by BASF Japan Ltd.
A-2: Pandex T-1190, ester polyurethane, melt viscosity 7570 poise, manufactured by Dainippon Ink & Chemicals, Inc.
A-3: Elastollan ET88511FG, ether-based polyurethane, melt viscosity 8220 poise, manufactured by BASF Japan Ltd.
<Phosphorus flame retardant (B)>
B-1: MPP-A (melamine polyphosphate), acid value 0.19 eq / kg, manufactured by Sanwa Chemical Co., Ltd.
B-2: EXOLIT AP-422 (ammonium polyphosphate), acid value 0.02 eq / kg, manufactured by Clariant Japan Co., Ltd.
<Epoxy compound (C)>
C-1: Blemmer CP-30, molecular weight 9000, epoxy equivalent 529 g / eq, manufactured by NOF Corporation.
C-2: Blemmer CP-50M, molecular weight 10,000, epoxy equivalent 310 g / eq, manufactured by NOF Corporation.
<Conducting agent (D)>
D-1: Denka black (acetylene black), average particle size 35 nm, manufactured by Denki Kagaku Kogyo Co., Ltd.
D-2: PEO-1 (polyethylene oxide), molecular weight 150,000 to 300,000, manufactured by Sumitomo Seika Co., Ltd.
Li: Lithium perchlorate, manufactured by Toyama Pharmaceutical Co., Ltd.

<Melt viscosity>
Melt viscosity is obtained by using the obtained composition compound with a flow tester CFT-500C (manufactured by Shimadzu Corporation), a test temperature of 200 ° C. and a test pressure of 9. 9 according to JIS K 7210 Annex C (reference). The apparent viscosity (η _ap ) at 8 MPa was measured and determined.

<Appearance>
Using a 20 mm uniaxial extruder equipped with an annular die having a lip diameter of 24 mm, the composition compound was produced at a set temperature of the extruder of 195 ° C. and a single-layer tubular film molded body having a thickness of 150 μm and a folding diameter of 40 mm. The degree of occurrence of wrinkles appearing on the surface of the molded body and the degree of tearing of the molded body were evaluated by visual observation, and were shown in the following four stages.
◯: No wrinkles on the entire surface of the molded body and no holes in the molded body.
Δ: Some wrinkles are generated on the entire surface of the molded body, and there is no hole in the molded body.
×: Wrinkles are generated on the entire surface of the molded body, and there is no hole in the molded body.
XX: Breaking occurs in the molded body.

<Flame retardance>
The obtained composition compound was formed into a 3 mm-thick compact by press molding, and an oxygen index defined by JIS K 7201 using a candle method combustion tester D-type (manufactured by Toyo Seisakusho Co., Ltd.). Was measured to evaluate flame retardancy.

<Volume resistivity>
The composition compound was press-molded at 190 ° C. for 10 minutes to produce a film molded body having a thickness of 150 μm. And the volume resistivity of the film molded object was measured by the applied voltage 10V using the resistivity measuring device (Hiresta) by Mitsubishi Chemical Corporation, and the HRS probe on the conditions of 23 degreeC and 50% RH.

[Examples 1-9, Comparative Examples 1-5]
Using a batch kneader, various raw materials were kneaded for 5 minutes at a kneader tank set temperature of 170 ° C. and a stirring blade rotation speed of 100 rpm at the rate shown in Table 1, and then pelletized using a pelletizer to compound the resin composition. Produced. After the compound of this resin composition was dried at 70 ° C. for 4 hours, the above-described characteristics were evaluated. These results are shown in Table 1.

As is clear from Table 1, the compositions of Examples 1 to 9 in which (A), (B), and (C) were blended in the proportions indicated in the present invention have a high oxygen index and an appropriate melt viscosity. There was also a good appearance of the molded body. Moreover, the tendency was the same even if the types of (A), (B), and (C) were changed.
On the other hand, in Comparative Example 1 in which (C) was not blended, the melt viscosity of the resin composition was low, so that drawdown occurred during extrusion molding, and a molded article having a good surface without wrinkles could not be obtained. It was. On the contrary, Comparative Example 2 in which the blending amount of (C) exceeds the range of the present invention has an oxygen index lower than 26% and did not show sufficient flame retardancy. Further, Comparative Example 3 and Comparative Example 4 in which (B) was not blended or the blending amount of (B) was less than the range of the present invention showed good moldability, but the oxygen index was 26%. It was lower and did not show sufficient flame retardancy. On the contrary, in Comparative Example 5 in which the blending amount of (B) exceeds the range of the present invention, the flame retardancy is good, but the melt elongation of the resin composition is very small in the molten state at the time of molding. In addition, the extrusion-molded body was broken, and a continuous molded body could not be obtained.

[Examples 10 to 12, Comparative Example 6]
Using a batch kneader, the various raw materials were kneaded for 5 minutes at a kneader tank set temperature of 170 ° C. and a stirring blade rotation speed of 100 rpm at the rate shown in Table 2, and then pelletized using a pelletizer to compound the resin composition. Produced. After the compound of this resin composition was dried at 70 ° C. for 4 hours, the above-described characteristics were evaluated. These results are shown in Table 2.

As is clear from Table 2, Examples 10 to 12 in which the conductive agent (D) was blended in the ratio shown in the present invention in addition to (A), (B), and (C) had good high oxygen index. Flame retardant. Further, a molded article having an appropriate melt viscosity, excellent molding processability, and a smooth surface without wrinkles was obtained. Moreover, the tendency was the same even if the kind of (D) was changed. Further, the obtained molded body exhibits a volume resistivity of 1 × 10 ⁴ to 1 × 10 ¹³ Ω · cm, which is regarded as a semiconductive region, and can be used in electrophotographic systems such as copying machines, facsimile machines, and printers, or electrostatic printing systems. It was suitable as a molded product used in an image forming apparatus for forming an image.
On the other hand, in Comparative Example 6 in which (C) was removed from the composition of Example 12, the melt viscosity was low and the molding processability was poor, and many wrinkles were generated on the surface of the molded body.

[Example 13]
Using a two-layer coextrusion machine equipped with an annular die having a lip diameter of 50 mm, a thickness consisting of an inner layer of 110 μm thickness composed of the composition compound of Example 11 and polyvinylidene fluoride (KYNAR710, melt viscosity 2900 poise, manufactured by Atofina) A tube-shaped film with a folding diameter of 120 mm was produced with a two-layer structure consisting of a surface layer of 40 μm.
The appearance of the obtained tubular film was good with no wrinkles, and the oxygen index was 30.6%, indicating excellent flame retardancy.

As described above, the flame retardant thermoplastic polyurethane composition of the present invention is a thermoplastic polyurethane having a low molecular weight even when the molecular chain of the thermoplastic polyurethane is broken during the molding process due to the presence of the phosphorus flame retardant. These molecules are bonded again through the epoxy compound. Accordingly, the flow characteristics at the time of melting are good, and the molding processability is excellent. For this reason, the flame-retardant thermoplastic polyurethane composition of the present invention can provide a molded article that exhibits a good appearance and is excellent in flame retardancy.
The flame-retardant thermoplastic polyurethane composition of the present invention having such a feature is molded by extrusion molding or the like and used for various applications. It is suitably used as a sheet material conveying belt, a transfer belt, an intermediate transfer belt, a fixing belt, a developing belt, a photoreceptor substrate belt, and the like in an image forming apparatus that forms an image by electrostatic printing. In addition, a conductive roll in which a similar seamless belt is covered with a metal or nonmetallic core rod is also suitably used as a charging roll, a toner supply roll, a developing roll, and a transfer roll.

Claims (7)

A composition containing no halogen, comprising a thermoplastic polyurethane (A), a phosphorus-based flame retardant (B), and an epoxy compound (C) having two or more epoxy groups in the molecule, wherein the heat in the composition The blending ratio of the plastic polyurethane (A) and the phosphorus-based flame retardant (B) is (A) :( B) = 92 to 45: 8 to 55 by weight ratio, and the total amount of (A) and (B) Flame retardant thermoplastic polyurethane composition for extrusion molding, comprising 0.1 to 30 parts by weight of epoxy compound (C) having two or more epoxy groups in the molecule per 100 parts by weight object. A composition obtained by further blending a conductive agent (D) with the composition according to claim 1, wherein the total amount of thermoplastic polyurethane (A) and phosphorus flame retardant (B) is 100 parts by weight. A flame retardant thermoplastic polyurethane composition for extrusion molding , wherein the conductive agent (D) is blended in an amount of 0.05 to 25 parts by weight. The flame retardant thermoplastic polyurethane composition for extrusion molding according to claim 2, wherein the conductive agent (D) is carbon black or grafted carbon black. The flame retardant thermoplastic polyurethane composition for extrusion molding according to claim 2, wherein the conductive agent (D) is a polymer having a polyalkylene oxide chain in the molecule. An extrusion- molded article comprising the flame-retardant thermoplastic polyurethane composition according to any one of claims 1 to 4. A molded product of a multilayer structure, of which extrudates at least more is characterized in that it consists of a flame retardant thermoplastic polyurethane composition according to any one of claims 1 to 4. It is a seamless belt shape, The extrusion molded object of Claim 5 or Claim 6 characterized by the above-mentioned.