RESIN COMPOSITION CONTAINING VAPOR GROWN CARBON FIBER AND USE THEREOF

CROSS-REFERENCE TO RELATED APPLICATIONS

This is an application filed pursuant to 35 U.S.C. Section 111 (a) with claiming the benefit of U.S . provisional application Serial No. 60/619,024 filed October 18, 2004, U.S. provisional application Serial No. 60/619, 025 filed October 18, 2004 andU.S. provisional application Serial No. 60/619,026 filed October 18, 2004 under theprovisionof 35U.S.C. lll(b), pursuant to 35 U.S.C. Section 119 (e) (1) .

TECHNICAL FIELD

The present invention relates to a resin composition for a seamless belt and a seamless belt obtained by molding the composition. More specifically, the present invention relates to a resin composition for a seamless belt to be used for a photoreceptor, a charge belt, a transfer belt, a fixing belt, or the like in an image forming apparatus such as an electrophotographic copyingmachine or a laserprinter, the resin composition being excellent in durability, heat resistance and surface smoothness, and the resin composition having stable electrical resistance properties, and a seamless belt using the composition.

Also, the present invention relates to a resin composition for a tray, excellent in heat resistance, antistatic property, etc., onto which tray a magnetic head for a hard disk drive is

mounted, and onwhich tray themagnetichead is processed, washed, transferred, stored, etc.; and a tray using the composition, for carrying a magnetic head for magnetic disk drive.

Also, the present invention relates to: an electroconductive thermoplasticresincomposition for afuel tube, containing as a conductive filler a specific vapor grown carbon fiber; and a fuel tube using the composition. More specifically, the present invention relates to: an electroconductive thermoplastic resin composition which has stable electrical resistance property, which is excellent in surface smoothness, toughness, extrusionmoldabiIityandthe like inabalancedmanner withoutimpairingtheelongationpropertyofathermoplasticresin itself, and which can be suitably used for a fuel tube for use inan automobile or the like; anda fuel tubeusing the composition.

BACKGROUND ART

In an electrophotographic device, a rotating body made of metal, plastic, rubber or the like is used for a photoreceptor, a charged body, a transferring member, a fixing member or the like. Known examples of rotating body include those having a drum-like shape and those made of resin having a belt-like shape.

Since a seam in a rotating body having a belt-like shape causes defects in an output image which are attributable to the seam, those having a belt-like shape need to be endless (seamless belt) with no seam.

In a case where a seamless belt is used as a rotating body, the belt requires heat resistance and heat cycle durability as well as mechanical properties such as tensile strength.

In addition, in a color laser printer or a color copying

machine utilizing an electrophotographic technique, since transcription or the like is repeated with toner of a basic color such as cyan, yellow, magenta or black, a seamless belt used in such printer or copying machine must have a small coefficient of thermal expansion and be excellent in dimensional stability.

Accordingly, thermosetting polyimide or a heat-resistant fluorine-based resin has been used for a seamless belt.

Meanwhile, it is important for a transfer belt, an intermediate transfer belt, a fixing belt or the like for electrophotography in a copying machine, a printer, or the like to have stable electrical resistance properties. In order to transfer and fix a toner image, it is necessary to regulate the electrical resistivity to be 10 ⁶ to 10 ¹³ Ω-cm. Furthermore, it is required that difference between the surface resistivity and the volume resistivity be small, that fluctuation in the surface resistivity and the volume resistivity with time be small and that the surface resistivity and the volume resistivity depend little on environmental changes.

Since thermosetting polyimide or a heat-resistant fluorine-based resin used for a seamless belt has insulating property, attempts have been made to add various conductive fillers to such polyimide or resin to reduce its resistance. Examples of conductive filler tobe generallyusedinclude: carbon materials each having a graphite structure such as carbon black, graphite, vapor grown carbon fiber and carbon fiber; metal materials such as metal fiber, metal powder and metal foil, and metal oxides; and inorganic filler coated with metal (JP 2000-248086 A, JP 2003-255640 A and JP 2003-246927 A) . In particular, it has been recently revealed that miniaturization

of conductive filler, increase in aspect ratio of the filler, increase in specific surface area of the filler or the like is effective for obtaining high conductivity with a small addition amount of the filler. In view of this, carbon black having an extremely large specific surface area and a hollow carbon fiber

(carbonnanotube) having a small filament diameterhavebeenused.

However, carbon black and carbon nanotube each have a large specific surface area and hence has large surface energy, so that agglomeration readily occurs and the dispersibility into a resin is poor. As a result, in a case where carbon black or the carbon nanotube is blended into a resin, there are problems of reduction in mechanical strength and variations in electrical resistance properties.

Since charge (static electricity) preventing property is required in trays for magnetic heads, such trays have been conventionallyproducedbymolding conductive resin compositions obtained by blending in and dispersing conductivity-imparting components such as an antistatic agent, carbon black and a carbon fiber into thermoplastic resins such as ABS, polycarbonate and modified polyphenylene ether (PPE) .

However, a compositioncompoundedwithanantistatic agent, whose electroconductive mechanism depends on ionic conduction, is susceptible to moisture in the environment. In addition, the antistatic agent flows out during washing or long-term use of the composition, which leads to reduction in the antistatic property. Furthermore, the addition of a large amount of antistatic agent causes a problem such as decrease in heat resistance.

Although carbonblack and a carbon fiber are not influenced

by humidity, washing and the like, they involve, for example, a problem that carbon particles or carbon fibers are apt to fall out of a molded product, to thereby damage a magnetic head.

To cope with those problems, in a case where a carbon fibril having an average fiber diameter of 200 nm or less is blended in, the problem that carbon fibers fall out of a molded product is reduced. Thus, use of such a carbon fibril (carbon nanofiber) as a conductivity imparting component is considered to be effective in preventing static electricity(JP 2001-310994 A) . However, a carbon fibril, having a large specific surface area andhencehigh surface energy, is apt to generate agglomerates and is hard to be dispersed into a resin. Therefore, a relatively large amount of carbon fibril must be blended in for imparting conductivity. However, the carbon fibril is extremely expensive, so it leads to an increase in production cost. Furthermore, a reduction in amount of carbon fibril to be added involves a disadvantage, that is, insufficient conductivity of a molded product to be obtained.

Hollow molded products of thermoplastic resins have been mainly used for, for example, the ducts in the engine rooms of automobiles, and are produced by subjecting polyamide-based resins to blow molding or by extrusion molding saturated polyester-basedresins, polyamide resins, polyolefin resins, and thermoplastic polyurethane into tubes. Polyamideresins (polyamide 11 andpolyamide 12) , polyester resins, and fluorine-based resins each having flexibility have been widely used for fuel tubes for automobiles. However, when a blow hollow molded product and a tube molded product are used inapplicationswhere anon-conductive liquidsuchas a fuel flows,

there arises a seriousproblem. That is, charge accumulates owing to friction between the inner wall of the tube and the fuel, and spark occurring at the time of discharge of the charge ignites the fuel to cause fire to occur. To prevent this problem, conductivityhasbeen impartedto the innermost layer of the tube. JP 08-261374 Adiscloses amulti-layer synthetic resin tube having an inner layer composed of an electroconductive thermoplastic molding material. The document shows a graphite-fibril having a fiber diameter of 10 ran and an aspect ratio of about 500 to 1,000 (that is, a carbon nanofiber) as a conductivityimpartingmaterial. JP 11-106647Aand JP 11-343411

Aeachdescribe carbonblackas a conductivityimpartingmaterial.

However, carbon black and a carbon nanotube each have a large specific surface area and hence has large surface energy, so each of them is apt to generate an agglomerate and has poor dispersibilityinto aresin. As a result, thesematerials involve many problems when blended into a resin, such as reduction in mechanical strength, difficulty in obtaining surface smoothness and wide variation in elecrtoconductivity due to localization.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a resin composition for a seamless belt showing stable electrical resistance properties and excellent in surface smoothness, durability and heat resistance and a seamless belt using the composition.

Another object of the present invention is to provide a tray for carrying amagnetic head for a magnetic disk drive, which tray is inexpensive, excellent in mechanical strength and an

antistatic property, from which carbon fibers do not fall off .

Still another object of the present invention is to provide an electroconductive thermoplastic resin composition that can be suitably used for a tube for a fuel, the composition showing stable electrical resistance property, and the compositionbeing excellent insurface smoothness, durability, andheat resistance.

The inventors of the present invention have made extensive studies with a view to achieving the above object. As a result, they have found that the above objects can be achieved by using a resin composition with a specific vapor grown carbon fiber blended therein as a conductive filler, thereby completing the present invention.

That is, one aspect of the present invention relates to: a resin composition for a seamless belt having the following constitution; a method of producing the resin composition; and a seamless belt using the resin composition.

[Al] A resin composition for a seamless belt, containing a heat-resistant resin having a glass transition temperature of 100 ⁰ C or higher and/or a melting point of 200 ⁰ C or higher and a vapor grown carbon fiber having an average filament diameter of 50 to 130 nm in an amount of 1 to 30 parts by mass with respect to 100 parts by mass of the heat-resistant resin, wherein the volume resistivity of the resin composition is within a range of 1 x 10 ⁵ to 1 x 10 ¹³ Ωcm. [A2] The resin composition for a seamless belt according to the above item Al, further containing conductive carbon black in an amount of 1 to 10 parts by mass with respect to 100 parts by mass of the heat-resistant resin. [A3] The resin composition for a seamless belt according to the

above item Al or A2, wherein the heat-resistant resin is at least one of thermoplastic resin and thermosetting resin. [A4] A resin composition for a seamless belt according to the above itemAl or A2, wherein the heat-resistant resin is at least one kind selected from a fluorine-based resin, polyimide, polyamide imide, polyether imide, polyether ether ketone, polysulfone, polyether sulfone, polybenzimidazole, polyphenylene sulfide, polyethylene naphthalate, polyallylate and an aromatic polyamide resin. [A5] The resin composition for a seamless belt according to the above item A4, wherein the heat-resistant resin is a fluorine-based resin, polyimide, polyamide imide, or polyether ether ketone. [Aβ] The resin composition for a seamless belt according to the above itemAl, wherein the vapor grown carbon fiber has a specific surface area of 10 to 50 m ² /g and an average aspect ratio of 65 to 500.

[A7] The resin composition for a seamless belt according to the above itemA6, wherein the vapor grown carbon fiber has a specific surface area of 15 to 40 m ² /g, and an average aspect ratio of 100 to 200.

[A8] The resin composition for a seamless belt according to any oneofthe above itemsAl, A6, andA7, whereinthenumberofbranches of the vapor grown carbon fiber per length is 0.3/μm or less. [A9] A method of producing the resin composition for a seamless belt according to any one of the above items 1 to 8, wherein vapor grown carbon fiber ismelt-blended into the heat-resistant resin, and at the time of melt-blending, breaking of the vapor grown carbon fiber filaments is suppressed to be 20% or less.

[AlO] A seamless belt consisting of the resin composition according to any one of the above items Al to A8, which is substantially unstretched.

[All] The seamless belt according to the above item AlO, wherein the thermal conductivity is 0.8 W/mK or more.

[A12] The seamless belt according to the above item AlO, wherein a ten point average roughness (Rz) at a cut-off wavelength of

2.5 mm is 10 μm or less.

[A13] The seamless belt according to the above item AlO, wherein the difference between surface resistivity and the volume resistivity is in 2 or less orders of magnitude.

[A14] The seamless belt according to the above itemAlO, in which a surface resistivity changes by 2 or less orders of magnitude upon application of a charging voltage. [A15] The seamless belt according to the above itemAlO, wherein a ratio (Ra/Rh) of a volume resistivity Ra at normal temperature and a normal humidity to a volume resistivity Rh at a high temperature and a high humidity is in the range of 0.03 to 30.

[A16] The seamless belt according to the above item AlO, wherein a ratio (Rioov/Riooov) of a volume resistivity Rioov when 100 V is applied to a volume resistivity Riooov when 1,000 V is applied in the range of 0.03 to 30.

[A17] The seamless belt according to any one of the above items

AlO to A16, which is used for a transfer belt, an intermediate transfer belt, a transfer/fixing belt, an intermediate transfer/fixing belt or a fixing belt for use in an image forming apparatus utilizing an electrophotographic technique.

The seamless belt of the present invention, which uses a specific vapor grown carbon fiber as a conductive filler, can

showmore stable electrical resistance properties (such as small difference between the surface resistivity and the volume resistivity, small fluctuation in the surface resistivity and thevolumeresistivitywithtime, andlowdependenceof the surface resistivityandthevolume resistivityonenvironmental changes) . In addition, the belt is excellent in surface smoothness, flexibility, durabilityandheat resistance (that is, inthebelt, wrinkles and dimensional changes hardly generate when it is repeatedly used for a long time period at a high temperature and underpressure) . Therefore, the belt can be preferably used for a photoreceptor belt, a charge belt, a transfer belt, a fixing belt or the like in an image forming apparatus such as a (color) laser printer or a (color) electrophotographic copying machine.

Another aspect of the present invention relates to a resin composition for a tray for carrying a magnetic head for a magnetic disk drive composed of the following constitution; a carrier tray using the same; and methods of producing them. [Bl] A resin composition for a tray for carrying a magnetic head for a magnetic disk drive, comprising a heat-resistant resin having a glass transition temperature of 100 ⁰ C or higher and/or a melting point of 200 ⁰ C or higher and a vapor grown carbon fiber having an average filament diameter of 50 to 130 nm in an amount of 1 to 30 parts by mass with respect to 100 parts by mass of the heat-resistant resin, wherein the volume resistivity of the resin composition is in the range of 1 x 10 ² to 1 x 10 ⁸ Ωcm. [B2] The resin composition for a carrier tray according to Bl, wherein the heat-resistant resin is at least one kind selected fromafluorine resin, polyimide, polyamide imide, polyether imide, polyether ether ketone, polysulfone, polyether sulfone,

polybenzimidazole, polyphenylene sulfide, polyethylene naphthalate, polyallylate, aromatic polyamide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, and a cycloolefin polymer. [B3] The resin composition for a carrier tray according to Bl, wherein theheat-resistant resinis apolyether ether ketone resin, a polycarbonate resin, a modified polyphenylene ether resin, polyphenylene sulfide, or a cycloolefin polymer. [B4] The resin composition for a carrier tray according to Bl, wherein the vapor grown carbon fiber has a specific surface area of 10 to 50 m ² /g and an average aspect ratio of 65 to 500. [B5] The resin composition for a carrier tray according to B4, wherein the vapor grown carbon fiber has a specific surface area of 15 to 40 m ² /g, and have an average aspect ratio of 100 to 200. [B6] The resin composition for a carrier tray according to Bl, wherein the number of branches of the vapor grown carbon fiber per length is 0.3/μm or less.

[B7] A method of producing the resin composition for a carrier tray according to any one of Bl to B6, wherein the vapor grown carbon fiber is melt-kneaded with the thermoplastic resin, and the breaking ratio of the vapor grown carbon fiber at the time of melt-mixing is suppressed to 20% or less.

[B8] A tray for carrying a magnetic head for a magnetic disk composed of the resin composition according to any one of Bl to B6, comprising an arm part, a head chip attached to the tip of the arm part and a lead wire connected to the head chip. [B9] The carrier tray according to B8, wherein the thermal conductivity is 0.8 W/mK or more. [BlO] The carrier tray according to B8, wherein in at least a

portion on which a magnetic head is to be mounted, the ten point average roughness (Rz) at a cut-off wavelength of 2.5 mm is 10 μm or less.

[BIl] The carrier tray according to B8, wherein, when the tray having a surface area of 100 to 1,000 cm ² is immersed in 500 ml of pure water and an ultrasonic wave of 40 KHz is applied to the tray for 60 seconds, the number ofparticles eachhaving aparticle size of 1 μm or more and falling off from the surface of the tray is 5,000 pcs/cm ² or less per unit surface area. [B12] The carrier tray according to B8, wherein the total amount ofoutgas is 1 μg/gor less inwhichthe amount ofmethylene chloride is 0.1 μg/g or less and the amount of hydrocarbons is 0.5 μg/g or less, in a surface area of 12.6 cm ² measured by means of a headspace gas chromatogram under conditions of a heating temperature of 85°C and an equilibrium time of 16 hours.

[B13] A method of producing a tray for carrying a magnetic head for a magnetic disk drive, wherein the resin composition for a tray for carrying a magnetic head for a magnetic disk drive according to any one of Bl to B6 is subjected to injectionmolding. The tray for carrying a magnetic head for a magnetic disk drive of the present invention uses a specific vapor grown carbon fiber which can be favorably dispersed as a conductive filler into a heat-resistant resin; and provide desired antistatic property even in a small amount. Unlike a case where carbon black is used, in a case of using the tray of the present invention, no falling-off of particles from the tray occurs and therefore, a magnetic head can be prevented from being damaged.

Still another aspect of the present invention relates to: an electroconductive thermoplastic resin composition for a fuel

tube composed of the following constitution; and a fuel tube using the composition.

[Cl] An electroconductive thermoplastic resin composition for a fuel tube, comprising a thermoplastic resin and vapor grown carbon fiber having an average filament diameter of 50 to 130 nm, wherein the volume resistivity is 1 x 10 ⁸ Ωcm or less and the stretch at break of the resin composition is 80% or more of the stretch at break of the thermoplastic resin alone. [C2] The electroconductive thermoplastic resin composition for a fuel tube according to the above Cl, in which the thermoplastic resin is polyamide, polyester, or a fluorine-based resin. [C3] The electroconductive thermoplastic resin composition for a fuel tube according to the above C2, in which the polyamide is one of PA6, PA46, PA66, PA612, PAlOlO, PAl012, PA69, PAIl, PA12, PA1212, PA6T, PA6I, PA12T, PA12I, and PA12/6T and 12/61 or a mixture of them.

[C4] The electroconductive thermoplastic resin composition for a fuel tube according to the above C2, in which the polyester- is at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and polybutylene naphthalate.

[C5] The electroconductive thermoplastic resin composition for a fuel tube according to the above C2, inwhich the fluorine-based resinisatleastoneofanethylene-tetrafluoroethylenecopolymer (ETFE) , a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer (THV) , an ethylene-chlorotrifluoroethylene copolymer (ECTFE) and polyvinylidene fluoride (PVDF) . [C6] The electroconductive thermoplastic resin composition for a fuel tube according to the above Cl, in which the vapor grown

carbon fiber has a specific surface area of 10 to 50 nr/g and an average aspect ratio of 65 to 500.

[C7] The electroconductive thermoplastic resin composition for a fuel tube according to the above C6, in which the vapor grown carbon fiber has a specific surface area of 15 to 40 rα ² /g, and have an average aspect ratio of 100 to 200.

[C8] The electroconductive thermoplastic resin composition for a fuel tube according to any one of the above Cl, C6 and C7, in which the number of branches of the vapor grown carbon fiber per length is 0.3/μm or less.

[C9] The electroconductive thermoplastic resin composition for a fuel tube according to the above Cl, in which the amount of the vapor grown carbon fiber in the resin composition is 10 mass% or less. [ClO] Amethod of producing the electroconductive thermoplastic resin composition for a fuel tube according to any one of the aboveCl toC9, whereinthevaporgrowncarbonfiber ismelt-kneaded with the thermoplastic resin and the breaking ratio of the vapor grown carbon fiber at the time of melt-kneading is suppressed to 20% or less.

[CIl] Afuel tubeusingthe electroconductivethermoplasticresin composition for a fuel tube according to any one of the above Cl to ClO. [C12] The fuel tube according to the above CIl, comprising a multi-layer structure where at least the innermost layer of the multi-layer structure is made of the resin composition. [C13] A method of producing a fuel tube having a multi-layer structure, comprising a multi-layer structure where at least the innermost layer of the multi-layer structure is made of the resin

composition for a fuel tube according to any one of the above Cl to ClO, whereinthe resincompositionandthe same thermoplastic resin composition as the former or another thermoplastic resin composition different from the former are subjected to co-extrusion molding.

The electroconductive thermoplastic resin composition for a fuel tube of the present invention is excellent in physical properties such as surface smoothness, toughness, and extrusion moldability in abalancedmannerwithout impairing the elongation property of a thermoplastic resin itself, so it can be suitably used for a fuel tube or any other tubular molded product for use in an automobile or the like.

BRIEF DESCRIPTION OF DRAWINGS Fig. I ¹ is an electron micrograph (magnification : X 2000) of the electroconductive resin composition obtained in Example 9.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail, in the order of (A) a resin composition for a seamless belt and a seamless belt, (B) a resin composition for a tray for carrying a magnetic head for a magnetic disk drive and a carrier trayand (C) anelectroconductivethermoplasticresincomposition for a fuel tube and a fuel tube.

(A) a resin composition for a seamless belt and a seamless belt

Aheat-resistant resin to be used in the present invention is required to be a heat-resistant resinhaving a glass transition

temperature of 100 ⁰ C or higher and/or a melting point of 200 ⁰ C or higher, and any one of thermoplastic and thermosetting resins can be used as long as the resin satisfies the above requirement . To be specific, at least one kind selected from a fluorine-based resin, a polyimide resin, a polyamide imide resin, a polyether imide resin, a polyether ether ketone resin, a polysulfone resin, a polyether sulfone resin, a polybenzimidazole resin, a polyphenylene sulfide resin, a polyethylene naphthalate resin, a polyallylate resin and an aromatic polyamide resin is preferable.

Of those, a fluorine-based resin, a polyimide resin (PI) , a polyamide imide resin (PAI) , or a polyether ether ketone resin (PEEK) is suitable.

The term "fluorine-based resin" refers to generally known fluorine resins of thermoplastic homopolymer or copolymer type. A resin having a glass transition temperature of 100 ⁰ C or higher and/or a melting point of 200 ⁰ C or higher is selected from such fluorine-based resins. Preferable examples of such resin include perfluoro-based copolymers. Specific examples of the perfluoro-based copolymers include: a copolymer of tetrafluoroethylene andperfluoroalkyl vinyl ether; a copolymer of tetrafluoroethylene and hexafluoropropylene; a copolymer of tetrafluoroethyleneandethylene (ETFE) ; andatertiarycopolymer of tetrafluoroethylene, hexafluoropropylene and perfluoroalkyl vinyl ether. Those polymers each have a heat distortion temperature under load of about 70 to 100 ⁰ C and a heat resistance up to about 150 to 260°C.

The term "polyimide resin" refers to all resins each having an imide bond in its structure, and examples of such resin include

thermoplastic and thermosetting polyimide.

Thermoplastic polyimide has an imide group and has thermoplasticity. Therefore, the polyimide itself can melt or soften at a predetermined temperature or higher, so the polyimide can be directly subjected to extrusion molding. The property is found in polyimide having in its main chain, (2 or more) ether bonds, an alkylene bond (having 3 or more carbon atoms) and a functional group that provides intramolecular flexibility such as a carbonyl group. To be specific, an organic dianhydride (such as pyromellitic dianhydride, 2, 2 ' , 3, 3'-biphenyltetracarboxylic dianhydride, 3, 3' , 4, 4 '-benzophenonetetracarboxylic dianhydrideorbis (2, 3-dicarboxyphenyl)methanedianhydride) and an organic diamine (such as bis{4- [3- (4-aminophenoxy)benzoyl]phenyl}ether, 4,4"-bis (3-aminophenoxy)biphenyl, bis{4- (3-aminophenoxy)phenyl}sulfone or

2, 2 '-bis{4- (3-aminophenoxy)phenyl}propane) equal to each other in amount are allowed to gradually react with each other while being stirred in an organic polar solvent (such as N-methylpyrrolidone or N,N-dimethylacetamide) . The reaction involves polycondensation into a polymer having a necessary molecular weight and imide ring closure after the polycondensation. As a result, the organic dianhydride and the organic diamine react to form polyimide in a single stroke. The temperature of extruding polyimide into a film is about 300 to 400 ⁰ C.

Thermosettingpolyimide does notmelt in apolyimide state . Therefore, molding of the thermosettingpolyimide into a seamless belt involves the two steps of: subjecting its precursor having

thermoplasticity, i.e. polyamic acid to primary molding; and subsequently transforming the resultant into an imide. For example, the polyimide can be produced by allowing an organic dianhydride (such as pyromellitic dianhydride, 2, 2 ' , 3, 3 '-biphenyltetracarboxylic dianhydride,

3, 3' , 4, 4 '-benzophenonetetracarboxylic dianhydride or bis (2,3-dicarboxyphenyl)methane dianhydride) and an organic diamine (such as p-phenylenediamine, 4, 4'-diaminodiphenyl, 4, 4' -diaminodiphenylmethane, or 4, 4 '-diaminophenyl ether) equal to each other in amount to gradually react with each other while stirring the organic dianhydride and the organic diamine in an organic solvent (such as N-methylpyrrolidone or N,N-dimethylacetamide) . The reaction is a polycondensation reaction for producing a polyamic acid having a desiredmolecular weight, andmust not involve a ring closure reaction to transform the resultant into an imide. For this purpose, the organic dianhydride and the organic diamine must be allowed to gradually react with each other while the reaction temperature is kept low. The above examples of polyimide have no amino group, but so-called polyamide imide containing an amino group can also be used. The polyamide imide can be produced through a polycondensation reaction between a tricarboxylic monoanhydride to serve as an organic acid and anyone of the organic diamines exemplified above equal to each other in amount in an organic solvent. The polyimide-based resin has a heat distortion temperature of 200 to 400 ⁰ C and heat resistance up to about 250 to 350 ⁰ C.

The vapor grown carbon fiber to be used in the present invention preferably has an average filament diameter of 50 to 130 nm. An average filament diameter of less than 50 nm results

in an exponential increase in surface energy, with the result that an agglomeration force between filaments drastically increases. If a vapor grown carbon fiber having such average filament diameter is merely kneadedwith a resin, the fiber cannot be sufficiently dispersed into the resin, which results in agglomerates of the fiber scattered in a resin matrix and therefore, a conductive network cannot be formed. When a large shearingforce is appliedat the time ofkneading, the agglomerates can be raveled out and the fiber can be dispersed into the matrix. However, since filaments are broken when the agglomerates are raveled out, desired conductivity cannot be obtained. On the other hand, if the average filament diameter exceeds 13o run, it is necessary to increase the amount of carbon fiber to be blended in order to obtain desired conductivity, which leads to adverse affects on physical properties such as a mechanical strength and flexibility.

It is preferable that the vapor grown carbon fiber to be used in the present invention have an aspect ratio of 65 to 500, more preferably 100 to 200. The larger the aspect ratio of the fiber (that is, the longer the filament) , the more entangled with each other and the more difficult it is to ravel out. As a result, the fiber cannot be sufficiently dispersed. On the other hand, if the aspect ratio is less than 65, 10 mass% or more of a filler must be added in order to form a conductive linked skeleton structure, which is not preferred in that fluidity and tensile strength of the resin is remarkably decreased.

The degree of branching of the vapor grown carbon fiber to be used in the present invention is preferably 0.3/μm or less,

more preferably 0.2/μm or less, or still more preferably 0.1/μm or less. If the degree of branching is in excess of 0.3/μm, the carbon fiber forms strongaggregates, therebymaking it difficult to impart conductivity efficiently with a small amount of the fiber.

In the vapor grown carbon fiber to be used in the present invention, the average interplaner spacing d _O o2 according to an X-ray diffraction method is preferably 0.345 nm or less, more preferably 0.343 nm or less, or still more preferably 0.340 nm or less. When the average interplaner spacing doos is in excess of 0.345 nm, graphite crystals have not sufficiently grown, so the resistivity of the carbon fiber alone increases to be 10 or more times as high as that of a crystallized fiber. Furthermore, when the carbon fiber is mixed with a resin or the like, electron transfer to and fro between the carbon fiber and the resin becomes difficult. To be specific, the same degree of conductivity as the conductivity obtained in the case of carbon fiberwhere graphite crystals have growncannotbeobtainedunless a filler is added in an amount twice or more. The vapor grown carbon fiber to be used in the present invention has a BET specific surface area of preferably 10 to 50 m ² /g, or more preferably 15 to 40 m ² /g. When the BET specific surface area increases, surface energy of the carbon fiber also increases to make adhesive and agglomeration forces stronger, which leads to difficulty in dispersing the fiber. Furthermore, since the interfacial areabetween thematrix and the carbon fiber increases, it is impossible to sufficiently cover the fiber with the matrix, or more carbon fiber may be peeled off the matrix. As aresult, whenacompositeofthe fiber andthe resin isproduced,

not only electrical conductivity but also mechanical strength deteriorates, which is not preferred.

The peak height ratio (Id/Ig) of a band ranging from 1341 to 1349 cm ^"1 (Id) to a band ranging from 1570 to 1578 cm ^"1 (Ig) in the Raman scattering spectrum of the vapor grown carbon fiber to be used in the present invention is preferably 0.1 to 1.4, more preferably 0.15 to 1.3, or still more preferably 0.2 to 1.2.

The vapor grown carbon fiber to be used in the present invention having the above physical properties can be produced by thermally decomposing a carbon source (an organic compound) in the presence of an organic transition metal compound.

Examples of carbon source (organic compound) to serve as a rawmaterial for the carbon fiber include gases such as toluene, benzene, naphthalene, ethylene, acetylene, ethane, anaturalgas, andcarbonmonoxide, andmixtures ofthegases . Ofthose, aromatic hydrocarbons such as toluene and benzene are preferable.

The organictransitionmetal compoundcontains atransition metal to serve as a catalyst. The transition metal is an element belonging to any one of Groups 4 to 10 in the periodic table. Examples of preferable organic transitionmetal compound include ferrocene and nickelocene.

A sulfur compound such as sulfur or thiophene can be used as a catalyst aidwhichenhances catalytic activitybyefficiently removing a gas such as hydrogen adsorbing to the surface of a transitionmetal catalyst particle in the atmosphere of a thermal decomposition reaction.

By using a reducing gas such as hydrogen as carrier gas, the above organic compound, the organic transitionmetal compound and the sulfur compound are supplied into a reactor heated to

800 to 1300 °C and cause a thermal decomposition, to thereby generate carbon fiber.

With respect to the form of raw materials, for example, the organic transition metal compound and the sulfur compound dissolved in aromatic hydrocarbon may be used, or the materials gasified at a temperature of 500 ⁰ C or less maybe used. However, in a case where the raw material is in liquid form, vaporization and decomposition of the raw material occur on the inner wall of the reaction tube, causing an uneven concentration- distribution , andthus generatedcarbon fibertends to aggregate.

Therefore, as the formof rawmaterials, the rawmaterial gasified in advance is preferred for the purposed of making the concentration of the material uniform inside the reaction tube.

The ratio of the transition metal catalyst to sulfur compoundcatalystaid (transitionmetal /transitionmetal+ sulfur compound) is preferably 15 to 35 mass %. If the ratio is less thanl5mass%, the catalyst activitybecomes too high, increasing the number of branching in the carbon fiber or producing radial carbon fiber filaments, which leads to increase in interaction betweenfilaments andunpreferable formationofstrongaggregates. If the ratio exceeds 35 mass%, since gas such as hydrogen adsorbed onto the catalyst cannot be sufficiently removed, which disturbs carbon source supply to the catalyst and leads to generation of particles other than carbon fiber, it is not preferred. The branching number of carbon fiber and the raveling level of filament agglomerates depend on raw material concentration at the time of reaction. That is, whenthematerial concentration in vapor phase is high, catalyst particles are formed by heterogeneous nucleation on the surface of the generated carbon

fiber, and additional carbon fiber is generated from the carbon fiber surface, to thereby form carbon fiber like a silver frost. Moreover, carbon fiber filaments obtained from materials having a high concentration readily tangle with each other and cannot be easily raveled out. Accordingly, it is preferable that the ratio of the supply amount of rawmaterial to the amount of carrier gas in the reaction tube be 1 g/1 or less, more preferably 0.5 g/1, even more preferably 0.2 g/1.

It is preferable to remove organic substance such as tar attached to the surface of the carbon fiber by heat-treatment in inert atmosphere at 900 to 1300 °C. Moreover, in order to increaseelectroconductivityofthe carbonfiber, itispreferable to conduct a heat treatment in inert atmosphere at 2000 to 3500 ⁰ C to thereby develop crystals. The furnace used for heat treatment to develop crystals may be any furnace as far as the furnace can hold the target temperatureof2000 °Corhigher, morepreferably2300 °Corhigher. For example, Acheson furnace, resistance furnace or high-frequency furnace may be used. Alternatively, the heat treatment may be conducted by directly applying an electrical current to the powder material or formed product in some cases.

The atmosphere of the heat treatment is non-oxidation, preferably inert atmosphere constitutedby one ormore rare gases of argon, helium and neon. With respect to the heat treatment time, in light of productivity, the shorter, the more preferable, and generally 1 hour is sufficient. When heating is performed foralongtimeperiod, the carbon fiberis sinteredandsolidified, so production yield deteriorates. Therefore, it is sufficient that, after the temperature at the central portion of a molded

product or the like has reached a target temperature, the temperature at the central portion be kept at the target temperature for 10 minutes to 1 hour.

In order to further develop crystals of carbon fiber and thereby increase electroconductivity, boron compound such as boron carbide (B ₄ C) , boron oxide (B ₂ O ₃ ) , elemental boron, boric acid(H ₃ BO ₃ ) or borate salt may be mixed into carbon fiber in conducting graphitization with heat treatment at 2000 to 3500 °C in inert atmosphere. The amount of the boron compound to be added depends on the chemical property and physical property of the compound and cannot be flatly limited. For instance, in a case where boron carbide (B ₄ C) is used, the amount is preferably 0.05 to 10 mass %, more preferably 0.1 to 5 mass % based on the carbon fiber. Throughthe heat treatmentwith additionofboron compound, carbon cryatallinity of carbon fiber is enhanced and electroconductivity is increased. The boron amount contained in the crystals of carbon fiber or in the surface of the crystals is preferably 0.01 to 5 mass %. For the purpose of improving electroconductivity of the carbon fiber and its affinity with resin, it is more preferable that the boron content be 0.1 mass % ormore. Further, since the upper limit of the boron amount which can substitute carbon in the graphenesheet is about 3 mass %, a larger amount of boron, especially 5 mass % or more of boron, which will remain as boron carbides or boron oxides to cause decrease in electroconductivity, is unpreferable.

For the purpose of increasing affinity between the carbon fiber and resin, carbon fiber may be subjected to oxidation treatment to thereby introduce phenolic hydroxyl group, carboxyl

group, quinone group or lactone group to the surface of the carbon fiber. Further, the carbon fiber may be subjected to surface treatment with a silane coupling agent, titanate coupling agent, aluminium coupling agent or phosphoric ester coupling agent or the like.

In the present invention, carbon black may also be added as a conductive filler. Whenavapor growncarbon fiber andcarbon black are used in combination and the carbon black is uniformly dispersed, a phenomenon that the range of variation in conductivity is narrowed is observed.

Carbon black that can be used generally has an average particle size of 1 to 500 μm and a volume resistivity of about 10 ¹ to 10 ⁴ Ω-cm. Examples thereof include acetyleneblack, Ketjen Black, oil furnace black and thermal black. The resin composition for a seamless belt of the present inventioncontains theheat-resistantresinandvapor growncarbon fiber described above, and optionally contains carbon black.

The blending amount of the vapor grown carbon fiber is 1 to 30 parts by mass, or preferably 3 to 15 parts by mass with respect to 100 parts by mass of the heat-resistant resin. If the blending amount of the vapor grown carbon fiber is less than

1 part by mass, it is difficult to form a conductive network, with the result that desired conductivity cannot be obtained. On the other hand, if the amount exceeds 30 mass %, flexibility as required for a seamless belt cannot be obtained.

When carbon black is blended in, the blending amount of carbonblack ispreferably 1 to 10 partsbymass, ormorepreferably

2 to 5 parts by mass with respect to 100 parts by mass of the heat-resistant resin. If the blending amount of carbon black

exceeds 10 parts by mass, flexibility as required for a seamless belt cannotbeobtained, therebycausinga largenumberofproblems such as reduction in surface smoothness.

It is preferable that at the time of mixing and kneading of the above respective components, breaking of the vapor grown carbon fiber filaments be suppressed as much as possible. To be specific, the breaking ratio of the vapor grown carbon fiber is suppressed to preferably 20 % or less, more preferably 15% or less, or still more preferably 10 % or less. The breaking ratio can be evaluated by comparing the aspect ratios (measured by means of, for example, a scanning electron microscope photographic image) of the carbon fiberbefore andafterthemixing and kneading.

For example, procedure as described below can be used in order to perform the mixing and kneading step while suppressing thebreakingofthevaporgrowncarbonfiberto the extentpossible.

In general, when an inorganic filler is melt-kneaded with a thermoplastic resin or a thermosetting resin, a high shearing force is applied to agglomerated inorganic filler to break the inorganic filler to thereby pulverize the inorganic filler, so that the inorganic filler isuniformlydispersedinamoltenresin. Examples of an available kneader for generating a high shearing force include a large number of kneaders such as one utilizing astonemillmechanismanda co-rotatingtwin screwextruderhaving a kneading disk introduced into screw elements, which can apply a high shearing force. However, when any such kneader is used, filaments of the vapor grown carbon fiber are broken in a kneading step. Althoughbreaking of the fiber filaments canbe suppressed in case of using a uniaxial extruder having a weak shearing force,

it is impossible to uniformly disperse the fiber. Therefore, in order to uniformly disperse the fiber while suppressing breaking of filaments, a co-rotating twin screw extruder using no kneading disk is desirably used to reduce a shearing force. Alternatively, a kneader such as a pressure kneader that does not apply a high shearing force and achieves dispersion over a long time period is desirably used. Alternatively, a special mixing element is desirably employed in a uniaxial extruder. The wettability of an inorganic filler with respect to a molten resin is important for filling the resinwith the inorganic filler. When an inorganic filler is introduced into a molten resin, it is indispensable to increase the area corresponding to an interface between themolten resin and the inorganic filler. An example of a method of improving wettability includes a method wherein the surface of vapor grown carbon fiber is oxidized.

When the vapor grown carbon fiber to be used in the present invention is downy with a bulk specific gravity of about 0.01 to 0.1 g/cm ³ , the fiber tends to involve the air, so deaeration by means of an ordinary uniaxial extruder or co-rotating twin screw extruder is difficult, and therefore it is difficult to fill the resinwith the carbon fiber. In such a case, abatch-type pressure kneader is preferably used as a kneader that has good filling property and can suppress breaking of filaments to the extent possible. The fiber kneaded by means of a batch-type pressure kneader can be fed into a uniaxial extruder before being solidified, to thereby be formed into pellets.

The resin composition for a seamless belt of the present invention can have a volume specific resistivity of 1 x 10 ⁶ to 1 x 10 ¹³ Ωcm, preferably 1 x 10 ⁷ to 1 x 10 ¹⁰ Ωcm, or more preferably

1 x 10 ⁸ to 1 x 10 ⁹ Ωcmby adjustingphysical properties andblending amount of the vapor grown carbon fiber.

After preparing a composition by mixing and dispersing the above components, the composition is molded into a seamless belt . A dry molding method or a wet molding method can be preferably used as a molding method.

The dry molding method is a method involving directly subjecting a matrix resin to melt extrusion molding through a ring die in a state where substantially no organic solvent is present. The wet molding method involves: subjecting a composition in a plasticized state or a solution state to primary molding in the presence of an organic solvent; removing a solvent or the like; and molding the resultant into a target seamless belt shape. In the primary molding, the composition in a plasticized state is molded into a tubular shape while casting the composition toward the outer periphery of a metal drum, or by directly subjecting the composition to extrusion molding through a ring die. A centrifugal casting method where a composition is poured in a solution state into a metal drum and molded while rotating the drum.

An organic solvent to be used in the wet molding method is selected from those which can swell or dissolve the heat-resistant resin (apolyamic acidinthe case of thermosetting polyimide) . The centrifugal casting method involves the use of an organic solvent into which the heat-resistant resin can be completely dissolved, and it is necessary to select the amount of the solvent.

Descriptionwillbegivenofanexampleofamethodofmolding a seamless belt by means of the centrifugal casting method using

thermosetting polyimide as a heat-resistant resin. First, starting materials are subjected to a polycondensation reaction in the organic solvent to produce a polyamic acid solution. A conductive filler is mixed therewith and dispersed into the solution as described above. Next, a predetermined amount of the polyamic acid solution is injected into a metal drum corresponding to a seamless belt having desired dimensions (diameter and width) , and rotation is started while the drum is heated fromthe outside of the drum. When the solution is centrifuged at a predetermined temperature (generally a temperature slightly higher than the boiling point of the organic solvent and lower than the temperature at which the solution is transformed into an imide) for a predetermined time period, the solvent is gradually evaporated and removed while the solution is uniformly flown over the entire inner surface of the drum. Thus, the polyamic acid is solidified and molded into an endless belt. The resultant endless belt is peeled off the drum and fit into a cylindrical mold, and the whole is placed into a heating oven, gradually heated to 250 ⁰ C at first, and then gradually heated to 400 ⁰ C (secondary molding) . During the heating, an imidation reaction gradually proceeds, whereby a seamless belt using thermosetting polyimide as a matrix is produced. The cylindrical moldused in the secondarymolding is intendedmainly for performing a secondary treatment while keeping the shape of the belt, and is not essential. A heat-resistant resin other than thermosetting polyimide can be molded by means of the centrifugal casting method in accordance with the same procedure as in the case of polyimide.

Other molding conditions are not particularly limited in

both of the dry molding method and the wet molding method, and optimumconditions are desirably selected in correspondence with a selected composition. However, in the dry molding method, the melt extrusion of the composition through a ring die is preferably performed at room temperature and the composition is preferably taken up substantially without stretching.

The seamless belt of the present invention thus produced is excellent in surface smoothness, and its ten point average roughness (Rz) at a cut-off wavelength of 2.5 mm is 10 μm or less, or preferably 8 μm or less.

The seamlessbelt ofthepresent invention canhave a thermal conductivity of 0.8 W/mK or more. If the thermal conductivity is 0.8 W/mK or more, the temperature of the seamless belt can be uniform, to thereby suppress the occurrence of, for example, wrinkles. In addition, the seamless belt can have good heat discharge property, and the maximum temperature that the belt can reach at the time of continuous use can be lowered, whereby the durability of the belt can be improved.

In addition, the seamless belt of the present invention has stable electrical resistance properties. To be specific:

(1) the ratio of the surface resistivity to the volume resistivity is within 2 or less orders of magnitude;

(2) fluctuation of the surface resistivity due to application of a charging voltage is within 2 or less orders of magnitude; (3) the ratio (Rioov/Riooov) of a volume resistivity Rioov when 100 V is applied to a volume resistivity Riooov when 1, 000 V is applied can be in the range of 0.03 to 30; and/or

(4) the ratio (Ra/Rh) of the volume resistivity Ra at normal temperature and a normal humidity to the volume resistivity Rh

at a high temperature and a high humidity can be in the range of 0.03 to 30.

Regarding the above item (1) : In a molded product of conventional resin composite material containing a conductive filler, there is a large difference between a surface resistivity and a volume resistivity, and a ratio (surface resistivity/volume resistivity) is often 10 ² or more. In the seamless belt using vapor grown carbon fiber of the present invention, however, the carbon fiber can be dispersed sufficiently, so the ratio can be less than 10 ² (difference between the surface resistivity and the volume resistivity is within 2 or less orders of magnitude) . Therefore, the seamless belt entirely shows stable electrical resistance property.

Regarding the above items (2) and (3) : When the seamless belt is used for a transfer belt, an intermediate transfer belt, or the like, a voltage must be controlled in accordance with the type of an image and the environment. If the resistivity fluctuates according to the voltage, the voltage control is difficult. Therefore, the less the resistivity depends on the voltage, themorepreferable. Inthe seamless belt of the present invention, the fluctuation range of the surface resistivity upon application of a charging voltage can be within 2 or less orders of magnitude (less than 10 ² ) , or preferably 1 or less order of magnitude (less than 10 ¹ ) . In addition, a ratio (Rioov/Riooov) of the volume resistivity Rioov when 100 V is applied to a volume resistivity Riooov when 1, 000 V is applied can fall within the range of 0.03 to 30, or preferably 0.1 to 10.

Regarding the above item (4) : In the seamless belt with a controlled resistivity to be used for a transfer belt, an

intermediatetransferbeltorthelike, fluctuationinresistivity due to the environment is preferably small . In the seamless belt of the present invention, a ratio (Ra/Rh) of a volume resistivity Ra at normal temperature and a normal humidity to a volume resistivity Rh at a high temperature and a high humidity can be adjusted to fall within the range of 0.03 to 30, or preferably 0.1 to 10. The term "at normal temperature and a normal humidity" as used herein refers to an environment having a temperature of 23 ⁰ C and a humidity of 55 %Rh and the term "at a high temperature andahighhumidity" as usedherein refers to an environment having a temperature of 30 ⁰ C and a humidity of 80 %Rh.

(B) resin composition for a tray for carrying a magnetic head for a magnetic disk drive and a carrier tray Aheat-resistant resin to be used in the present invention is a heat-resistant resin having a glass transition temperature of 100 ⁰ C or higher and/or a melting point of 200 ⁰ C or higher, and any one of thermoplastic and thermosetting resins can be used as long as the resin satisfies the conditions. To be specific, at least one kind selected from a fluorine resin, polyimide, polyamide imide, polyether imide, polyether ether ketone, polysulfone, polyether sulfone, polybenzimidazole, polyphenylene sulfide, polyethylene naphthalate, polyallylate, an aromatic polyamide resin, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, and a cycloolefin polymer is preferable.

Ofthose, polycarbonate (PC) , polyether ether ketone (PEEK) , modifiedpolyphenylene ether (PPE) , polyphenylene sulfide (PPS) , ora cycloolefinpolymerispreferable interms ofheat resistance,

dimensional accuracy, and cost.

The vapor grown carbon fiber to be used is the same as used in above (A) .

The resin composition for a tray for carrying a magnetic head for a magnetic disk drive contains the above heat-resistant resin and the vapor grown carbon fiber.

The blending amount of the vapor grown carbon fiber is 1 to 30 parts by mass, or preferably 3 to 15 parts by mass with respect to 100 parts by mass of the heat-resistant resin. If the blending amount of the vapor grown carbon fiber is less than 1 part by mass, it is difficult to form a conductive network, with the result that desired conductivity cannot be obtained. On the other hand, if the amount exceeds 30 parts by mass, impact resistance significantly deteriorates. Mixing/kneading of the above components maybe carried out in the same manner as described in the above (A) .

The resin composition for a carrier tray of the present invention can be controlled to have a volume specific resistivity of 1 x 10 ² to 1 x 10 ⁸ Ωcm, preferably 1 x 10 ³ to 1 x 10 ⁸ Ωcm, or more preferably 1 x 10 ⁴ to 1 x 10 ⁷ Ωcm which is suitable for a tray for carrying a magnetic head for a magnetic disk drive, by adjusting physical properties, blending amount, and the like of the vapor grown carbon fiber. The surface resistivity of the resin composition can be regulated to be 1 x 10 ² to 1 x 10 ¹⁰ Ω/D or preferably 1 x 10 ⁴ to 1 x 10 ⁸ Ω/D.

With resistivity controllable to be within the above range, not only an excellent antistatic property but also prevention of excessive contact current from flowing into a magnetic head which is caused by contact between the magnetic head and the tray

can be achieved.

The above respective components are mixed and dispersed to prepare a composition, and the composition is molded into a carrier tray. The molding can be performed bymeans of a general method. To be specific, the resin composition obtained by means of the above method is molded by means of any one of various melt-moldingmethods . Examples of amoldingmethod includepress molding, extrusion molding, vacuum molding, blow molding, and injection molding. Of those, injection molding is preferable. In addition to general injection molding methods, any one of various molding methods such as: integral molding of a metal part and any other part by means of an insert injection molding method; a two-color injection molding method; a core back injection molding method; a sandwich injection molding method; and an injection press molding method can be used as an injection moldingmethod. Sincethe surface resistivityof aproductvaries depending on a resin temperature, a die temperature and a molding pressure, appropriateconditionsmustbe set ininjectionmolding.

A side gate, a film gate, a submarine gate, a pin gate or the like can be used as a gate (inlet) for injecting the resin composition from a cavity of a die in an injectionmoldingmethod. The sectional areas of those gates are each desirably 0.2 mm ² or more.

Of those, a pin gate which does not require gate processing after molding is desirable in terms of productivity. In this case, it is preferable that the diameter of the pin gate be 0.5 to 3 mm, or particularly desirably 1.0 to 2.5 mm. With respect to the gate diameter of the pin gate, smaller, themore preferable, as far as the die can be sufficiently filled with a resin, and

the gate diameter is generally 0.2 to 0.5 mm. However, if the gate diameter (sectional area) is too small, the conductive network formed by vapor grown carbon fiber is apt to be broken due to excessive shear force imposed to the resin composition when it flows through the gate. On the other hand, an excessively large gate diameter makes the gate portion of a molded product less clear, with the result that the molded product is badly finished.

The resin composition of the present invention has good fluidity and good mold transferability. With a gate relatively large as described above, the transferability can be enhanced. In the mold for the molded product, it is desirable that a flat portionhavinganangle of 80 to 100 degrees (nearlyperpendicular) against the parting face have a smooth surface. When the plane nearly perpendicular to the parting face has a rough surface, since such irregularities are transferred onto the resin, a large force is required to take a product out of the mold, which leads to defects such as breakage of the molded product. Therefore, the ten point average roughness (Rz) of the plane nearly perpendicular to the parting plane at a cut-off wavelength of 2.5 mm is preferably 10 μm or less, more preferably 5 μm or less, or still more preferably 3 μm or less.

The carrier tray sometimes corrodes and damages a magnetic head by virtue of a gas generated from the tray. The amount of such a gas generated fromthe carrier trayof thepresent invention is preferably small. To be specific, the total amount of outgas from a surface area of 12.8 cm ² measured by means of a headspace gas chromatogram under the conditions of a heating temperature of 85 ⁰ C and an equilibrium time of 16 hours is preferably 1 μg/g

or less, more preferably 0.5 μg/g or less, the amount of methylene chloride generated is 0.1 μg/g or less, more preferably 0.02 μg/g or less, and the amount of hydrocarbons genetated is 0.5 μg/g or less, more preferably 0.2 μg/g or less. Examples of the hydrocarbon include n-heptane, n-hexane, cyclohexane, benzene, and toluene, which are used in producing a resin. To obtain such a tray, it is desirable that the resin composition be degassed to remove volatile components during its production process or that a heat-resistant resin polymerized by a method not using a polymerization solvent.

The carrier tray of the present invention preferably has a surface excellent inuniformity and stability. To be specific, when the tray having a surface area of 100 to 1, 000 cm ² is immersed in 500 ml of pure water and an ultrasonic wave of 40 KHz is applied to the tray for 60 seconds, the number of particles each having a particle size of 1 μm or more and falling off from the surface of the tray (particle generation) is 5, 000 pcs/cm ² or less. Such a tray can prevent a magnetic head from being physically or chemically contaminated and damaged by particles that fall out as a result of scratching, abrasion and washing.

If the particle generation exceeds 5, 000 pcs/cm ² , it causes contamination and damage by the particles that fall off at the timeofscratching, abrasion, washing, orthe like. Inthepresent invention, it is particularly desirable that the particle generation be 1,000 pcs/cm ² or less.

The carrier trayof thepresent invention canhave a thermal conductivity of 0.8 W/mK or more. With thermal conductivity of 0.8 W/mK or more, heat radiation can contribute to drastic improvement in deformation and damage of the tray at the time

of handling on and after heat treatment step.

(C) an electroconductive thermoplastic resin composition for a fuel tube and a fuel tube Examples of thermoplastic resin used in the present invention includes polyamide, polyester and fluorine-based resin.

The polyamide is a resin mainly composed of an amino acid, lactam, or a diamine and a dicarboxylic acid, and examples of its main component include: amino acids such as 6-aminocapronic acid, 11-aminoundecylic acid, 12-aminododecanoic acid and para-aminomethylbenzoic acid; lactams such as ε-aminocaprolactam and ω-laurolactam; aliphatic, alicyclic, and aromatic diamines such as tetramethylenediamine, hexamethylenediamine, undecamethylenediamine, dodecamethylenediamine,

2, 2, 4-/2, 4, 4-trimethylhexamethylenediamine,

5-methylnonamethylenediamine, metaxylenediamine, paraxylylenediamine, 1, 3-bis (aminomethyl) cyclohexane, 1, 4-bis (aminomethyl) cyclohexane, l-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, bis (4-aminocyclohexyl)methane, bis (3-methyl-4-aminocyclohexyl)methane,

2, 2-bis (4-aminocyclohexyl)propane, bis (aminopropyl)piperazine, aminoethylpiperazine and

2-methylpentamethylenediamine; and aliphatic, alicyclic, and aromatic dicarboxylic acids such as adipic acid, spelic acid, azelaicacid, sebacicacid, dodecanedioic acid, terephthalicacid, isophthalic acid, 2-chloroterephthalic acid,

2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid and hexahydroisophthalic acid.

In the present invention, each of polyamide homopolymers and copolymers derived fromthose rawmaterials maybe used alone, or two or more of them may be used as a mixture.

Specific examples of the polyamide homopolymers and copolymers include PA6, PA46, PA66, PA612, PAlOlO, PA1012, PA69, PAIl, PA12, PA1212, PA6T, PA6I, PA12T, PA12I, and PA12/6T and 12/61. Of those, a homopolyamide resin composed of structural units having an average carbon number per one amide group of 8 to 15 or a copolymerized polyamide resin having an average carbon number per one amide group of 8 to 15 is preferable with a view to obtaining improved toughness and improved extrusion moldability. Preferable examples of such polyamide include PA12, PAIl, PA1112 and PA1212.

Examples of the polyester include polyesters obtained from dicarboxylic acids and aliphatic diols. Examples of the dicarboxylic acids include: aliphatic dicarboxylic acids each having 2 to 20 carbon atoms such as terephthalic acid, azelaic acid, sebacic acid, adipic acid, dodecanedicarboxylic acid and isophthalicacid; aromaticdicarboxylic acids suchas isophthalic acid and naphthalenedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. Each of them may be used alone, or two or more of them may be used as a mixture. Examples of the aliphatic diols include ethylene glycol, propylene glycol, 1, 4-butanediol, trimethylene glycol, 1, 4-cyclohexanedimethanol, and hexamethylene glycol.

Examples of a preferable thermoplastic polyester include

polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polycyclohexylenedimethylene terephthalate, and polyethylene naphthalate. Of those, polybutylene terephthalate having an appropriate mechanical strength, or a copolyester composed of: a dicarboxylic acid component containing 60 mol% or more (preferably 70 mol% or more) of terephthalic acid, and dodecanedicarboxylic acid and/or isophthalic acid; and a 1, 4-butanediol component is particularly preferably used, The fluorine-basedresinis agenerallyknown fluorine resin which is composed of a thermoplastic resin alone or is formed as a result of copolymerization of thermoplastic resins, and is preferably a perfluoro-based copolymer. Specific examples thereof include: a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether; a copolymer of tetrafluoroethylene and hexafluoropropylene; a copolymer of tetrafluoroethylene and ethylene (ETFE); andatertiarycopolymeroftetrafluoroethylene, hexafluoropropylene, and perfluoroalkyl vinyl ether.

The vapor grown carbon fiber to be used is the same as used in above (A) .

The above resin composition contains the above heat-resistant resin and the above vapor grown carbon fiber. The blending amount of the vapor grown carbon fiber is 10 mass % or less in the resin composition, preferably 2 to 8 mass %. If the blending amount exceeds 10 mass %, the stretching property of the resin composition deteriorates. Further, if the blending amount is too small, electroconductivity as desired cannot be obtained.

Mixing/kneading of the above components may be carried out

in the same manner as described in the above (A) .

The resin composition of the present invention can be adapted to have a volume specific resistivity of 1 x 10 ⁸ Ωcm or less, preferably 1 x 10 ² to 1 x 10 ⁸ Ωcm, or more preferably 1 x 10 ⁴ to 1 x 10 ⁷ Ωcm by adjusting the physical properties and loadings of the vapor grown carbon fibers.

The resin composition of the present invention can suppress a reduction in breaking elongation due to the compounding of the above specific vapor grown carbon fibers as a conductive filler. Therefore, the resin composition can be said to be a material that brings together excellent conductivity and excellent elongation property. To be specific, when the breaking elongation (%) of a resin alone compounded with no vapor grown carbon fiber is denoted by A (%) and the breaking elongation of the resin composition of the present invention prepared by compounding the resin with vapor grown carbon fibers is denoted by B (%) , a maintenance factor (B/A x 100 (%) ) of the breaking elongation of the conductive resin composition to the breaking elongationofthe resinalone canbe 80% ormore. Thevalue reduces to about 20% when carbon black or a carbon nanotube is used as a conductive filler.

The composition of the present invention is suitable for producing a hollow molded product such as a tube molded product or a blow molded product, and is particularly suitable for producing a multi-layer hollow molded product through co-extrusion. In the case where the composition of the present inventionis appliedto a fuel tubehaving amulti-layer structure, the innermost layer of the structure is preferably formed of the composition. In this case, the same material as that for the

innermost layer may be used for an outer layer or for, if the multi-layer structure has three or more layers, an intermediate layer of the structure. Alternatively, the electroconductive thermoplastic resin composition of the present invention having a composition different from that of the innermost layer may be used therefor. A thermoplastic resin composition compounded with no conductivity imparting material may also be used. Examples of the thermoplastic resin composition compounded with no conductivity impartingmaterial includepolyamide, polyester, and a fluorine-based resin.

EXAMPLES

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the examples.

Examples 1 to 6, and Comparative Examples 1 to 9

Table 1 shows the compounding conditions for Examples and

Comparative Examples. Aresin and a conductive filler were melt- kneaded in accordance with the formulation shown in Table 1, and the kneaded product was molded into a film for measuring a volume specific resistance.

Details about a resin anda conductive fillerused, amethod of measuring the agglomerate of the conductive filler, kneading conditions, molding conditions, and a method of evaluating a molded film are shownbelow. Table 1 also shows a volume specific resistance, evaluation on the presence or absence of an agglomerate, and the breaking ratio of a fiber in each of Examples and Comparative Examples.

[Kneading method] i) Thermoplastic resin

A co-rotating twin screw extruder (PCM30) manufactured by IKEGAIwasused. Kneadingwasperformedat atemperatureof280 ⁰ C. ii) Thermosetting resin

A pressure kneader manufactured by Toshin Chemitech Co., Ltd. (having a kneading volume of 10 liters) was used. The temperature was set to 60°C.

[Molding method] i) Thermoplastic resin

A copolymer of tetrafluoroethylene and ethylene (ETFE: manufactured by ASAHI GLASS CO., LTD., AfIon type COP-55AXT, melting point: 260 ⁰ C) was used as a fluorine-based resin. A uniaxial extruder Laboplastomill (manufactured by Toyo Seiki Seisaku-Sho, Ltd.) and a cylindrical film molding die (having a diameter of 10 cm and a thickness of 200 μm.) were used. Molding was performed at 290 ⁰ C. ii) Thermosetting resin

ADMFsolutionofpolyamicacid (havinga solidconcentration of 18.5% and a viscosity of 3,000 poise) , which had been obtained by using 4, 4 '-diaminodiphenyl ether as an aromatic diamine and pyromellitic dianhydride as an aromatic tetracarboxylic dianhydride, was used. A specific amount of vapor grown carbon fiber was added to the solution, and the resultant dispersion liquid was kneaded. Next, the resultant was cast into a cylindrical SUS, andthe wholewas treated at 140 ⁰ C for 15minutes, 200 ⁰ C for 20 minutes, 25O ⁰ C for 30 minutes, 300 ⁰ C for 30 minutes, and350 ⁰ C for 30minutes . Thus, ablackpolyimide tubularproduct having a thickness of about 50 μm was produced.

[Vapor grown carbon fiber] i) VGCF (registered trademark) : Vapor grown carbon fiber manufactured by SHOWA DENKO K.K. (average filament diameter: 150 run, average filament length: 10 μm, specific surface area: 13 JR ² Zg, aspect ratio: 67, I ₀ = 0.2) was used. In addition, the fiber was pulverized by means of a jet mill to have an adjusted average filament length of 5 μm (aspect ratio: 33) . ii) VGCF-S: Vapor grown carbon fiber manufactured by SHOWA DENKO K.K. (average filament diameter: 100 run, average filament length: 11 μm, specific surface area: 20 m ² /g, aspect ratio: 110, I ₀ = 0.2) was used. In addition, the fiber was pulverized by means of a jet mill to have an adjusted average filament length of 5 μm (aspect ratio: 50) . iii) VGNF (registered trademark) : Vapor grown carbon fiber manufactured by SHOWA DENKO K.K. (average filament diameter: 80 nm, average filament length: 10 μm, specific surface area: 25 TO ² Zg, aspect ratio: 125, I ₀ = 0.2) was used. In addition, the fiber was pulverized by means of a jet mill to have an adjusted average filament length of 5 μm (aspect ratio: 63) . iv) Carbon nanotube (CNT: hollow carbon fibril) : A PEI master batchmanufacturedbyHyperionCatalysis (RMB 8515-00: containing 15mass% ofCNT) was used. The CNThadanaverage filament diameter of 10 nm, an average filament length of 5 μm, a specific surface area of 250 m ² /g (catalogue value) , and an aspect ratio of 500. [Conductive carbon black]

AKetjenBlack (KB) EC600JDmanufacturedbyLIONCORPORATION having a specific surface area of 800 mVg was used.

[Methods of measuring and evaluating physical properties] The physical properties of a film-like sample which was

cut out of the tubular product obtained by molding the resin composition as described above were measured and evaluated according to the following methods. i) Volume resistivity and surface resistivity in thickness direction

Four 10 cm-square pieces were cut out of the sample, and were left for 24 hours in a normal-temperature-and-normal-humidity environment (having a temperature of 23°C and a humidity of 55%Rh) and in a high-temperature-and-high-humidity environment (having a temperature of 30 ⁰ C and a humidity of 80%Rh) . The volume resistivity and surface resistivity of each sample was measured at 100Vbymeans of adigitalultra-highresistance/micro-current meter R8340 manufacturedbyADVANTEST CORPORATION and an HRprobe manufactured by Mitsubishi Chemical Corporation in each of the environments. ii) Agglomerate of carbon fiber: The broken-out section of the film-like samplewas observedwith a scanning electronmicroscope (at a magnification of 2,000), and the presence or absence of fiber agglomerates was determined according to the following criteria.

Size of an agglomerate (longitudinal diameter) O: Less than 0.5 μm

Δ: 0.5 μm or more and less than 5 μm x : 5 μm or more iii) Breaking ratio of carbon fiber (%) : The breaking ratio of carbon fiber filaments was determined from the following expression.

Breaking ratio of carbon fiber (%) = {1 - (Aspect ratio

of carbon fiber in molded product of composition/Aspect ratio of carbon fibers before mixing and kneading) } x 100

Here, the aspect ratio was measured and calculated through observation with a scanning electron microscope. iv) Raman scattering spectrum: The peak intensity ratio of 1360 cm ^"1 to 1580 cm ^"1 (I ₀ was measured. v) Ten point average roughness (Rz) :

The sum of the average absolute value of the height of the five highest peaks and the average absolute value of the depth ofthe five deepestvalleysmeasuredinadirectionof longitudinal magnification from the average line of a roughness curve was calculated. vi) Thermal conductivity: Thermal conductivity was measured according to a hot-wire method by means of a quick thermal conductivity meter manufactured by Kyoto Electronic

Manufacturing Co., Ltd. A test sample used was obtained by laminating films so as to have a shape of 100 x 100 x 2 mm thick.

Table 1

Examples 7 to 12, and Comparative Examples 10 to 18

Table 2 shows the compounding conditions for the compositions of Examples andComparative Examples. Aresin and a conductive filler were melt-kneaded in accordance with Table 2, and the kneaded product was subjected to injection-molding, to thereby obtain a flat plate for measuring a volume specific resistance.

Details about the resin, the conductive filler, the kneading conditions, themoldingconditions andthe evaluationmethod are shown below. Table 2 also shows the volume specific resistance, presence or absence of an agglomerate, the breaking ratio, the thermal conductivity, the ten point average roughness, the outgas amount, and the amountofparticles fallingoffthe sample eachobtainedinExamples and Comparative Examples.

Also, Fig.1 shows anpicture of scanningelectronmicroscope(at amagnificationof 2, 000) of the conductive resin composition obtained in Example 9.

[Thermoplastic resins used] i) Polycarbonate resin (PC) : Panlite (registered trademark) L-1225L manufactured by TEIJIN CHEMICALS LTD. ii) Modified polyphenylene ether resin (m-PPE) : NORYL (registered trademark) 534 manufactured by GE Plastics [Kneading method]

Aco-rotatingtwinscrewextruder (PCM30) manufacturedbyIKEGAI was used. PC andm-PPEwere kneadedat temperatures of 270 ⁰ Cand260 ⁰ C, respectively. [Molding method]

An injection molding machine having a clamping force of 75 ton with with SYCAP control package, manufactured by Sumitomo Heavy

Industries, Ltd. was used to mold a flat plate (measuring 100 x 100 x 2 mm thick) . PC and m-PPE were molded at temperatures of 280 ⁰ C and 270 ⁰ C, respectively. [Vapor grown carbon fiber] The same vapor grown carbon fiber was used as above. [Carbon black]

The same carbon black was used as above. [Methods of measuring properties to be evaluated] i) Volumespecificresistance:Avolumespecificresistancewasmeasure d by means of a four-prove method in accordance with JIS K7194. ii) Agglomerates of carbon fiber, the breaking ratio and the Raman scattering spectrum were measured in the same manner as above, iii) Thermal conductivity: The thermal conductivity was measured according to a hot-wiremethodbymeans of a quick thermal conductivity meter manufactured by Kyoto Electronic Manufacturing Co., Ltd. iv) Ten point average roughness (Rz) :

The sum of the average absolute value of the height of the five highest peaks and the average absolute value of the depth of the five deepest valleys which were measured in a direction of longitudinal magnificationfromthe averagelineofaroughness curvewas calculated, by using a surface roughness meter "Surfcom" manufactured by TOKYO SEIMITSU with a cut-off wavelength of 2.5 mm, a measuring length of 5 mm and a measuring speed of 0.3 mm/s. The heights of the lowest bottom to the fifth lowest bottom were v) Falling-off of particles

A flat plate sample of 100 mm x 100 mm x 2 mm was immersed in 500ml ofpurewater andanultrasonicwave of 40 KHzwas appliedthereto for 60 seconds. After that, the extracted pure water was sucked with a submerged particle counter, and the number of particles each having

a particle size of 1 μm or more was measured, vi) Measurement of the outgas amount

The amounts of n-heptane and methylene chloride and the total amount of outgas were measuredbymeans of a headspace gas chromatogram in accordance with the method described in JP 2001-118222 A. The measurement method is specifically described as follows.

Two pieces of samples of 22 mm x 10 mm x 3 mm (having a total surface area of 12.6 cm ² ) to serve as analysis samples were cut out of a tray, and a gas was extracted in a vial having a volume of 22 mL where 10 μL of n-octane was added as an internal standard substance under the conditions ofaheatingtemperature of 85°C andanequilibrium time of 16 hours. The gas generated in the vial was measured by means of a gas chromatogram (GC/MS) . The measurement was performed under the following conditions. Apparatus: "GC/MS QP5050" manufacturedby Shimadzu Corporation

Column: CHROMPAK PORAPLOT Q 0.32 mm ^χ 25 m

Column temperature: 35 to 240 ⁰ C (10°C/min)

Inlet temperature: 230 ⁰ C

Interface temperature: 280 ⁰ C Tray gas: Helium

Inlet pressure: 100 KPas

Total flow rate: 60 mL/min

Injection rate: 2mL

The total outgas amount, the amount of methylene chloride, and the amount of n-heptane were calculated as follows.

Total outgas amount (μg/g) = (Total peak area of sample - Total peak area of blank) / (Peak area of n-octane/Mass of n-octane (g) ) x 1/ (Mass of sample (g) )

Amount of methylene chloride (μg/g) = (Peak area of methylene

chloride) / (Peak area of n-octane/Mass of n-octane (g) ) x 1/ (Mass of sample (g) )

Amount of heptane (μg/g) = (Peak area of heptane)/ (Peak area of n-octane/Mass of n-octane (g) ) x 1/ (Mass of sample (g) )

Table 2

* ND: less than 0.01 μg/g in an amount of outgas

* ND: less than 0.01 μg/g in an amount of outgas

Impact resistance was significantly low in comparative Examples 8 and 9.

Examples 13 to 17, and Comparative Examples 19 to 25

Table 3 shows the compounding conditions for the compositions preparedinExamplesandComparativeExamples. Aresinandaconductive fillerweremeltedandkneadedinaccordancewiththe formulation shown

in Table 3, and the kneadedproduct wasmolded into a film formeasuring a volume specific resistance.

Details about a resin used, a conductive filler, kneading conditions, molding conditions, an evaluation method for the molded film, and the like are shown below. Table 3 also shows the results of Examples and Comparative Examples.

[Synthetic resins used] i) ETFE (copolymer of tetrafluoroethylene and ethylene) : Neoflon ETFE EP-540 manufactured by DAIKIN INDUSTRIES, LTD., tensile elongation: 300 % ii) PA12 (polyamide 12; polydodecaneamide) : Grilamid L20HL manufactured by EMS-SHOWA DENKO K.K., tensile elongation: 250 % iii) PBTE (polybutylene terephthalate elastomer) : Pelprene P80C manufactured by Toyobo co., Ltd., tensile elongation: 250 % [Kneading method]

Aco-rotatingtwinscrewextruder (PCM30) manufacturedby IKEGAI was used. A PBT elastomer, ETFE and PA12 were kneaded at 260 ⁰ C (PBT elastomer), 280 ⁰ C (ETFE) and 210 ⁰ C (PA12) , respectively. [Molding method]

A sycap-type injectionmoldingmachine having a fastening force of 75 ton manufactured by Sumitomo Heavy Industries, Ltd. was used to mold a flat plate (measuring 100 x 100 x 2 mm thick) from each the PBT elastomer, ETFE, and PA12 at 270 ⁰ C (PBT elastomer) , 290 ⁰ C (ETFE) and 230 ⁰ C (PA12), respectively. [Vapor grown carbon fibers]

The same vapor grown carbon fiber was used as above. [Conductive carbon black]

The same carbon black was used as above.

[Methods of measuring and evaluating properties] i) Volumespecificresistance:Avolumespecificresistancewasmeasure d by means of a four-prove method in accordance with JIS K7194. ii) Agglomerates of carbon fiber, the breaking ratio and the Raman scattering spectrum were measured in the same manner as above. iii) Thermal conductivity: Thermal conductivitywasmeasuredaccording to a hot-wire method by means of a quick thermal conductivity meter manufactured by Kyoto Electronic Manufacturing Co., Ltd. iv) Tensile elongation and elongation ratio: A tensile elongation was measuredinaccordancewithISO527. Anelongationratiowascalculated as a ratio (B/A x 100 (%) ) of the tensile elongation (B) to the tensile elongation (A) of a resin compounded with no conductive filler.

Table 3

ιJ->

Example 18 :

A tube having an outer diameter of 5 mm, an inner diameter of 3 mm, an inner layer thickness of 1 mm, an outer layer thickness of 1 mm and a length of 30 cm was produced by subjecting the resin composition of Example 15 (temperature 220 ⁰ C) for the inner layer and PA12 (temperature 220 ⁰ C) for the outer layer to co-extrusion by means of a multi-layer tube extruder equipped with two uniaxial extruders manufactured by SOUKEN CO., LTD.

10 tubes each having the above constitution were prepared, and were left for 4 hours in a cooling device at - 40 ⁰ C. After that, the tubes were taken out of the cooling device, and a spindle of 0.454 kg was allowed to fall onto the tubes from a height of 304.8 mm. As a result, none of the tubes was broken. Similarly, the resin composition of Comparative Example 24 using KB as a conductive filler was used to evaluate a strength at a low temperature in the same way. As a result all of 10 tubes were broken.