JP6808418B2 - Semi-conductive polyamide resin composition, molded article using it, and seamless belt for electrophotographic - Google Patents

Description

A semi-conductive polyamide resin composition containing a polyamide resin and an electron conductive material that can be suitably used in the field of seamless belts for electrophotographic used in an image forming apparatus using an electrophotographic method, and molding using the same. Regarding seamless belts for body and electrophotographic.

In addition to drum-shaped and roller-shaped members, transfer material transport members, intermediate transfer members, electrophotographic photosensitive members, fixing members, etc. used in image forming devices using electrophotographic methods such as copiers and laser beam printers are also included. Belt-shaped xerographic seamless belts may be used.

As the seamless belt for electrophotographic, a seamless belt containing a thermoplastic resin as a main component is generally used. A seamless belt containing a thermoplastic resin as a main component has an advantage that it can be manufactured at low cost and a general-purpose molding machine can be used.

Among the thermoplastic resins, the polyamide resin has excellent properties such as high breaking elongation and high elastic modulus, and therefore a proposal to use the polyamide resin for a seamless belt for electrophotographic photography has already been made (Patent Documents). 1. See Patent Document 2 and Patent Document 3).

On the other hand, in order to impart semiconductivity to the thermoplastic resin, it is common to mix an electron conductive material such as carbon black (CB) or a metal oxide in the thermoplastic resin. These electron-conducting materials are characterized by a small change in electrical resistance with respect to changes in the usage environment, but since they exhibit conductivity by contact with the electron-conducting materials, dispersion in the resin is important. is there. For this reason, these electronically conductive materials have a large variation in electrical resistance due to a slight change in concentration or a dispersed state, and the conductivity drops sharply with a certain amount of addition (percoration phenomenon). Therefore, the volume resistivity is 10 ⁶ to 10 It is difficult to control to a semi-conductive region of ¹³ Ω · cm.

In recent years, it has been proposed to use fine carbon fibers such as carbon nanotubes (CNT) instead of CB as the electron conductive material (see Patent Documents 4 and 5). Since this fine carbon fiber has a large aspect ratio (length / outer diameter), it is possible to impart conductivity to the resin with a relatively small amount of compounding as compared with CB and the like, and the addition amount and conductivity Since the relationship between the two changes linearly, it has a feature that the conductivity can be easily controlled.

By the way, it is known that the electrical resistance of a seamless belt for electrophotographic photography increases (increased energization) as energization is repeatedly performed in an image forming apparatus. The increase in energization of this seamless belt for electrophotographic is that even if the optimum transfer current value for transferring the toner image is set for the initial resistance value in the electrophotographic image formation, the toner image is increased after the resistance is increased. Transfer is not performed optimally, which may cause image defects. In order to suppress the transfer failure of the toner image, it is generally said that the increase in energization of the seamless belt for electrophotographic photography must be within one digit. For this reason, in addition to the uniformity of electrical resistance (variation in electrical resistance and small change in electrical resistance due to environmental changes), the seamless belt for electrophotographic used in electrophotographic image forming devices is energized with electrical resistance. It is required that the rise is small (the rise in energization is within one digit).

JP 2000-347513 JP 2001-142315 JP 2001-350347 JP-A-2004-339316 JP 2012-168529

However, a molded product using a resin composition in which fine carbon fibers are mixed with a polyamide resin such as nylon 6 or nylon 12 is excellent in the uniformity of electric resistance in the semi-conductive region, but on the other hand, the electric resistance is energized. There is a problem that the rise is large.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a semi-conductive polyamide resin composition having excellent uniformity of electrical resistance in a semi-conductive region and a small increase in electrical resistance. ..

As a result of diligent studies to solve the above problems, the present inventors have made a semi-conductive polyamide resin composition containing a polyamide resin composed of a diamine constituent unit derived from xylylenediamine and a dicarboxylic acid constituent unit and fine carbon fibers. By doing so, it was found that a molded product having a small increase in electrical resistance energization can be obtained, and the present invention has been completed.

According to the present invention
(1) 80 to 99% by weight of the polyamide resin (A) composed of a diamine constituent unit containing a constituent unit derived from xylylene diamine as a main component and a dicarboxylic acid constituent unit, and 20 to 1 of fine carbon fibers (B) . Seamless belt for electrophotographic which contains a semi-conductive polyamide resin composition layer composed of % by weight and has a volume resistivity of 1.0 × 10 ^{7 to} 1.0 × 10 ¹² Ω · cm. Is provided,
(2) The electrophotograph according to claim 1, wherein the xylylenediamine is one selected from a mixture of metaxylylenediamine, paraxylylenediamine, and metaxylylenediamine and paraxylylenediamine. For seamless belts are provided,
(3) The seamless belt for electrophotographic according to any one of claims 1 or 2, wherein the dicarboxylic acid contains a structural unit derived from an aliphatic dicarboxylic acid having 4 to 20 carbon atoms as a main component. Being done
(4) The seamless belt for electrophotographic according to claim 3, wherein the aliphatic dicarboxylic acid is sebacic acid or adipic acid.
(5) The seamless belt for electrophotographic according to any one of claims 1 to 4, wherein the fine carbon fiber is at least one selected from single-walled carbon nanotubes and multi-walled carbon nanotubes.

Since the semi-conductive polyamide resin composition of the present invention has high uniformity of electric resistance and a small increase in energization of electric resistance, it can be suitably used as a seamless belt for electrophotographic.

Hereinafter, the present invention will be described in detail.

[Semi-conductive polyamide resin composition]
The semi-conductive polyamide resin composition of the present invention comprises a polyamide resin (A) composed of a diamine constituent unit and a dicarboxylic acid constituent unit containing a constituent unit derived from xylylenediamine as a main component, and fine carbon fibers (B). , Contain. By using such a semi-conductive polyamide resin composition of the present invention, it is possible to obtain a molded product having high uniformity of electric resistance and a small increase in energization of electric resistance.

The blending ratio of the polyamide resin (A) and the fine carbon fibers (B) in the semi-conductive polyamide resin composition is not particularly limited, but is fine with respect to 80 to 99% by weight of the polyamide resin (A). The carbon fiber (B) is preferably contained in an amount of 20 to 1% by weight, and the fine carbon fiber (B) is more preferably contained in an amount of 10 to 1% by weight based on 90 to 99% by weight of the polyamide resin (A). If the blending amount of the fine carbon fibers (B) exceeds 20% by weight, the semi-conductive polyamide resin composition is inferior in extrusion suitability, so that the surface of the obtained molded product may not be smooth. Further, the amount of the fine carbon fiber (B) is less than 1 wt%, it becomes difficult to impart the performance of the volume resistivity of the semiconductive region ^{(10 6 ~10 13 Ω · cm} ).

[Polyamide resin (A)]
The polyamide resin (A) is composed of a diamine structural unit and a dicarboxylic acid structural unit whose main component is a structural unit derived from xylylenediamine. Here, the main component refers to a component that accounts for 50 mol% or more of the diamine constituent unit or the dicarboxylic acid constituent unit, and the same applies hereinafter.

[Diamine constituent unit]
The polyamide resin (A) used in the present invention contains, as a main component, a structural unit in which the diamine structural unit constituting the polyamide resin (A) is derived from xylylenediamine. The content of the structural unit derived from xylylenediamine is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 90 mol% or more, based on the total diamine constituent units.

The above-mentioned xylylenediamine is preferably metaxylylenediamine, paraxylylenediamine or a mixture thereof, and from the viewpoint of obtaining excellent toughness, metaxylylenediamine or a mixture of metaxylylenediamine and paraxylylenediamine. Is more preferable, and a mixture of m-xylylenediamine and paraxylylenediamine is particularly preferable. When xylylenediamine is a mixture of metaxylylenediamine and paraxylylenediamine, the content of metaxylylenediamine in the mixture of metaxylylenediamine and paraxylylenediamine from the viewpoint of obtaining excellent toughness. The amount is preferably 10 to 99 mol%, more preferably 40 to 95 mol%, and particularly preferably 60 to 90 mol%.

The diamine structural unit may include a structural unit derived from a diamine other than xylylenediamine. Diamines other than xylylenediamine include tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2. , 4-trimethyl-hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine and other aliphatic diamines; 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,3 -Diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminomethyl) decalin, bis (aminomethyl) tricyclodecane, etc. Alicyclic diamines; diamines having an aromatic ring such as bis (4-aminophenyl) ether, paraphenylenediamine, bis (aminomethyl) naphthalene; and the like can be exemplified, but are not limited thereto. .. The polyamide resin (A) can contain one or more structural units derived from these diamines.

[Dicarboxylic acid constituent unit]
The dicarboxylic acid constituent unit constituting the polyamide resin (A) used in the present invention is not particularly limited, but is derived from at least one selected from aliphatic dicarboxylic acids having 1 to 20 carbon atoms, terephthalic acid, and isophthalic acid. It is preferably a unit, more preferably a structural unit derived from an aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and particularly preferably a structural unit derived from an aliphatic dicarboxylic acid having 4 to 12 carbon atoms. ..

Examples of the aliphatic dicarboxylic acid having 4 to 20 carbon atoms include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,10-decandicarboxylic acid, and 1,11-undecandicarboxylic acid. Examples thereof include 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid.

Among the above, a structural unit derived from at least one selected from adipic acid and sebacic acid is preferable, and a structural unit derived from sebacic acid is more preferable. The polyamide resin (A) can contain one or more of these carboxylic acid constituent units.

The dicarboxylic acid structural unit preferably contains a structural unit derived from an aliphatic dicarboxylic acid having 4 to 20 carbon atoms as a main component. The content of the constituent unit derived from the aliphatic dicarboxylic acid having 4 to 20 carbon atoms in the dicarboxylic acid constituent unit is more preferably 70 to 100 mol%, particularly preferably 85 to 100 mol%.

[Fine carbon fiber (B)]
The fine carbon fibers used in the present invention are those having a hollow space in the core of the fibers, preferably in the form of fibers having a small fiber diameter and a high aspect ratio, and also include those commonly called carbon nanotubes. Specifically, it is preferable that the average fiber diameter is 1 nm to 200 nm, the average fiber length is 0.1 μm to 100 μm, and the aspect ratio is in the range of 10 to 10,000.

Examples of the fine carbon fibers include single-walled carbon nanotubes, multi-walled carbon nanotubes (Japanese Patent Laid-Open No. 3-64606, JP-A-3-77288, JP-A-2004-299986), and cup-laminated carbon nanotubes (Japanese Patent Laid-Open No. 2003-73928, JP-A-2004-). 360099), platelet-type carbon nanofibers (Japanese Patent Laid-Open No. 2004-360391), bell-shaped structure-connected aggregate carbon nanotubes (Japanese Patent Laid-Open No. 2012-46864, JP-A-2011-47081, JP-A-2011-46852) and the like. Among these, in the bell-shaped structural unit assembly, the connecting portion of the bell-shaped structural unit aggregate that is connected by a weak van der Waals force is easily separated at the joint by the shearing force in kneading or extrusion. However, it is preferable because it does not easily form an agglomerate in which microcarbon fibers are entangled with each other and has excellent dispersibility.

If necessary, the semi-conductive polyamide resin composition of the present invention may contain additives as long as its properties are not impaired. Additives include ionic conductive materials, electron conductive materials such as carbon black and metal oxides, antioxidants, heat stabilizers, organic fillers and inorganic fillers, plasticizers, lubricants, compatibilizers, processing aids, etc. Examples include pigments. Appropriate amounts of these additives can be used according to their respective purposes.

[Manufacturing method of semi-conductive polyamide resin composition]
The method for producing the semi-conductive polyamide resin composition of the present invention is not particularly limited, but for example, a polyamide resin (A), fine carbon fibers (B), and an additive used as necessary are blended and dried. A method of blending, a method in which a polyamide resin (A) is melt-kneaded in advance and a predetermined amount of fine carbon fibers (B) and an additive used as necessary are blended therein, and a predetermined amount of the polyamide resin (A) is blended. A method of blending fine carbon fibers (B) and various additives used as necessary and then melt-kneading. A predetermined amount of fine carbon fibers (B) is blended with a polyamide resin (A), and then melt-kneaded. A method of producing a master batch and melt-kneading the master batch and the polyamide resin (A) at the time of extrusion molding can be mentioned. From the viewpoint of uniformly mixing the polyamide resin (A) and the fine carbon fibers (B), it is preferable to have a step of blending a predetermined amount of the fine carbon fibers with the polyamide resin and melt-kneading.

Examples of the apparatus for melt-kneading include various known extruders such as a batch type kneader, a kneader, a conider, a Banbury mixer, a roll mill, and a single-screw or twin-screw extruder. Among these, a single-screw extruder or a twin-screw extruder is preferably used because of its excellent kneading ability and productivity.

The temperature at the time of melt-kneading can be appropriately selected depending on the type of the polyamide resin (A) used, the melt viscosity, etc., but is usually in the range of 185 ° C. to 300 ° C. to prevent deterioration of the polyamide resin (A) and moldability. From the viewpoint of the above, the temperature is preferably 190 to 280 ° C.

From the viewpoint of moldability, the melt viscosity of the semi-conductive polyamide resin composition is preferably 1,000 to 50,000 poise, more preferably 1,500 to 40,000 poise, and even more preferably 2,000 to 30,000 poise. If the melt viscosity is less than 1000 poise, when the composition is melt-extruded, drawdown may occur due to the low melt viscosity, and wrinkles resulting in molding defects may occur. On the other hand, if the melt viscosity exceeds 50,000 poise, the extrusion pressure (compressive stress and shear stress) increases during melt extrusion, so that the composition may generate heat and gel may be generated. The melt viscosity can be measured by using a conventionally known measuring machine, for example, using an heightened flow tester manufactured by Shimadzu Corporation equipped with a die having a length of 10 mm and a diameter of 1 mm.

[Molded product]
The molded product of the present invention contains the above-mentioned semi-conductive polyamide resin composition of the present invention. Further, the semi-conductive polyamide resin composition of the present invention may be used for at least a part of the molded product. Examples of the form of the molded body include a film shape, a sheet shape, a tube shape, a belt shape, and the like.

The molded product of the present invention can be produced, for example, by molding the above-mentioned semi-conductive polyamide resin composition into various forms by a conventionally known molding method. Examples of the manufacturing method include molding methods such as injection molding, extrusion molding, compression molding, vacuum forming, and press molding.

When producing a film or sheet-shaped molded product, an extrusion molding method provided with a flat die is preferable. As an extrusion molding method including a flat die, for example, an extruder and a flat die are arranged below the extruder so as to communicate with the extruder, and below the flat die, melting extruded from the flat die is performed. A semi-conductive resin composition in which a semi-conductive polyamide resin composition is supplied to an extruder using an extrusion molding apparatus in which a cooling roll and a touch roll for cooling the resin are arranged, and melted and pressurized. Is extruded into a film from the tip of a flat die and cooled and solidified with a cooling roll to form a film or sheet-like molded product.

On the other hand, when producing a tubular or belt-shaped molded product, an inflation extrusion molding method is preferable. As an inflation extrusion molding method, for example, an extruder and an annular die are arranged below the extruder so as to communicate with the extruder, and a molten resin extruded downward from the annular die is placed below the annular die. Using an extrusion molding device provided with a mandrel that is supported on the outer circumference and cooled and solidified, the semi-conductive polyamide resin composition is supplied to the extruder, and the melted and pressurized semi-conductive polyamide resin composition is cyclic. Examples thereof include a method of extruding a tube from a die, supporting it on the outer periphery of a mandrel, and cooling and solidifying it to form a tubular molded body. At that time, the tube-shaped molded body can be cut into a desired width to obtain a belt-shaped molded body.

When the above extrusion molding method is used, the molding temperature at the time of extrusion molding can be appropriately selected depending on the type of the polyamide resin (A) used, the melt viscosity and the like, but is usually in the range of 185 ° C. to 300 ° C. From the viewpoint of preventing deterioration of the polyamide resin (A) and moldability, the temperature is preferably 190 to 280 ° C.

Although the above description relates to a single layer, in the case of two layers, another extruder is arranged, and the composition in a molten state from each extruder is placed on a flat die or an annular die for two layers. It can be obtained by feeding and extruding two layers simultaneously from a flat die or an annular die. When there are three or more layers, an extruder may be prepared according to the number of layers.

The molded product containing the semi-conductive polyamide resin composition of the present invention includes molded products such as automobile-related parts, OA equipment parts, electronic / electrical parts, mechanical parts, packaging films, hollow containers, pipes, tubes, hoses, etc. It can be suitably used as various molded products, fibers and the like.

[Seamless belt for electrophotographic]
Among the above, the molded product of the present invention has a uniform electrical resistance (variations in electrical resistance and a small change in electrical resistance due to environmental changes) and a small increase in electrical resistance due to energization, so that it is seamless especially for electrophotographic. It can be suitably used as a belt. The electrophotographic seamless belt referred to here is a transfer transfer belt or an intermediate transfer belt used in an electrophotographic image forming apparatus.

Further, the electrophotographic belt of the present invention preferably has a predetermined electrical characteristics and mechanical properties as a transfer conveyor belt or an intermediate transfer belt, for example, the volume resistivity of the belt-shaped molded product is 1.0 × 10 ⁶ It is preferably ~ 1.0 × 10 ¹³ Ω · cm and the tensile modulus is 1000 to 5000 MPa. The volume resistivity is more preferably 5.0 × 10 ^{6 to} 5.0 × 10 ¹² Ω · cm, and further preferably 1.0 × 10 ^{7 to} 1.0 × 10 ¹² Ω · cm. .. The tensile elastic modulus is more preferably 1500 to 4500 MPa, more preferably 1800 to 4000 MPa.

Hereinafter, the present invention will be described in more detail with reference to Examples. The method for measuring the physical properties performed in the examples is as follows.
(1) Melt Viscosity The melt viscosity was measured using a high-grade flow tester manufactured by Shimadzu Corporation equipped with a die having a length of 10 mm and a diameter of 1 mm. In addition, the unit was expressed as (poise).
(2) Variations in electrical resistivity (volume resistivity) and electrical resistance Using a high-rester UP (MCP-HT450, manufactured by Dia Instruments) with a URS probe attached, 3 points of 100 mm x 1000 mm samples in the TD direction and in the MD direction. The volume resistivity was measured at a total of 60 points at 20 points. The average value of the measured values of the volume resistivity at the above 60 points was obtained, and this was used as the volume resistivity of the sample. (Measurement conditions: temperature 23 ° C., relative humidity 50% RH, load 2 kg, applied voltage 500 V, 10 seconds) In addition, variations in the measured values of volume resistance were obtained and evaluated based on the following evaluation criteria.
◯: Volume resistivity variation is within 1.0 digit ×: Volume resistivity variation exceeds 1.0 digit (3) Increased energization of electrical resistivity (volume resistivity) Using the following device, a voltage of 500 V is applied to the sample. Was applied continuously for 5 hours, the current value was read at predetermined time intervals, and the volume resistivity at each predetermined time was calculated using the following formula. Next, the obtained volume resistivity was converted into the common logarithm notation, and calculated by subtracting the volume resistivity in the common logarithm notation before the voltage application from the volume resistivity in the common logarithm notation after the voltage was applied.
-Power supply: MODEL 610C (manufactured by Trek), applicable voltage: 500V
-Electrode: P-618 (main electrode outer diameter 50 mm, guard electrode inner diameter 70 mm (with conductive rubber on both sides), manufactured by Kawaguchi Electric Works)
・ Ammeter: DIGITAL MULTIMETER (manufactured by IWATSU)
ρv = (V [V] / I [A]) x (W [cm] x L [cm]) / t [cm]
[Here, V = applied voltage [V], I = measured current value [A], W × L = area of main electrode [cm ² ] = 19.625 cm ² , t = thickness [cm]]
(4) Tension elastic modulus A sample having a width of 10 mm and a length of 200 mm was cut out in the MD direction of the obtained molded body, and a value of the tensile elastic modulus was obtained from a strain-stress curve using an autograph (AGS-100) manufactured by Shimadzu Corporation. Asked. (Test conditions: Chuck distance 100 mm, speed 50 mm / min) Further, the TD direction was also measured in the same manner, and the average value in the MD direction and the TD direction was taken as the tensile elastic modulus (MPa) of the sample.

The following raw materials were used.
<Polyamide resin (A)>
Polyamide resin (A-1) [melting point: 190 ° C., specific gravity: 1.13, manufactured by Mitsubishi Gas Chemical Company, product name: LEXTER8000 (xylylenediamine and sebacic acid)]
Polyamide resin (A-2) [melting point: 240 ° C., specific gravity: 1.21, manufactured by Mitsubishi Gas Chemical Company, product name: nylon MXD6 S6001 (xylylenediamine and adipic acid)]
Polyamide resin (A-3) [Nylon 12, Tm: 178 ° C., specific gravity: 1.02, melt viscosity: 1700 poise (measurement temperature 200 ° C., load 100 kg)]
Polyamide resin (A-4) [Nylon 12, Tm: 178 ° C., specific gravity: 1.02, melt viscosity: 5400 poise (measurement temperature 200 ° C., load 100 kg)]
<Fine carbon fiber (B)>
-Fine carbon fiber (B) [bell-shaped structural unit aggregate, average fiber diameter: 11 nm, DBP oil absorption: 330 ml / 100 g, specific surface area: 230 m ² / g]

[Preparation of masterbatch]
90% by weight of the polyamide resin (A-1) and 10% by weight of the fine carbon fibers (B) were melt-kneaded using a twin-screw kneader extruder having a screw diameter of 38φ mm to prepare a masterbatch of 10% by weight of the fine carbon fibers. ..

[Example 1]
The masterbatch and the polyamide resin (A-1) were dry-blended so as to have the blending ratios shown in Table 1, and the obtained mixture was simply provided with a flat die (set temperature: 218 ° C., lip width 150 mm). It was supplied to a shaft extruder and extruded into a film in a molten state (extrusion speed: 1.2 m / min). Then, this film-shaped molten resin is discharged onto a chill roll (surface set temperature: 30 ° C., air gap: 100 mm) whose surface is mirror-finished, cooled while being pressed by a touch roll, and is in the form of a film having a thickness of 170 μm. A semi-conductive polyamide resin molded product was obtained. Table 1 shows the measurement results of the volume resistivity, the uniformity of the electric resistance, and the increase in the energization of the electric resistance of the obtained film-shaped molded body.

[Examples 2 to 4, Comparative Examples 1 to 3]
In the same manner as in Example 1, each film-shaped molded product was obtained under the compounding ratio and processing conditions shown in Table 1. Table 1 shows the measurement results of the volume resistivity, the uniformity of the electric resistance, and the increase in the energization of the electric resistance of each of the obtained film-shaped molded bodies.

As shown in Table 1, a semi-conductive polyamide containing a polyamide resin (A) and fine carbon fibers (B) composed of a diamine constituent unit containing a constituent unit derived from xylylenediamine as a main component and a dicarboxylic acid constituent unit. The molded products of Examples 1 to 4 made of the resin composition showed a high uniformity of electric resistance in the semi-conductive region and a small increase in energization of the electric resistance. On the other hand, as shown in Table 1, the molded products of Comparative Examples 1 to 3 containing fine carbon fibers in nylon 12 show a high uniformity of electric resistance, but the result that the energization increase of the electric resistance exceeds an order of magnitude. showed that.

As described above, according to the present invention, a half containing a polyamide resin (A) and fine carbon fibers (B) composed of a diamine constituent unit containing a constituent unit derived from xylylenediamine as a main component and a dicarboxylic acid constituent unit. Since the conductive polyamide resin composition has high uniformity of electric resistance and a small increase in energization of electric resistance, a molded body that can be suitably used as a seamless belt for electrophotographic can be obtained.

Claims (5)

The polyamide resin (A) composed of a diamine constituent unit containing a constituent unit derived from xylylene diamine as a main component and a dicarboxylic acid constituent unit is 80 to 99% by weight, and the fine carbon fiber (B) is 20 to 1% by weight. A seamless belt for electrophotographic photography , which comprises a semi-conductive polyamide resin composition layer composed of , and has a volume resistivity of 1.0 × 10 ^{7 to} 1.0 × 10 ¹² Ω · cm . The seamless belt for electrophotographic according to claim 1, wherein the xylylenediamine is one selected from m-xylylenediamine, paraxylylenediamine, and a mixture of m-xylylenediamine and paraxylylenediamine. .. The seamless belt for electrophotographic according to any one of claims 1 or 2, wherein the dicarboxylic acid contains a structural unit derived from an aliphatic dicarboxylic acid having 4 to 20 carbon atoms as a main component. The seamless belt for electrophotographic according to claim 3, wherein the aliphatic dicarboxylic acid is sebacic acid or adipic acid. The seamless belt for electrophotographic according to any one of claims 1 to 4, wherein the fine carbon fibers are at least one selected from single-walled carbon nanotubes and multi-walled carbon nanotubes.