Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G15/00—Apparatus for electrographic processes using a charge pattern
  • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
  • G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G15/00—Apparatus for electrographic processes using a charge pattern
  • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
  • G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
  • G03G15/1665—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat
  • G03G15/167—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat at least one of the recording member or the transfer member being rotatable during the transfer
  • G03G15/1685—Structure, details of the transfer member, e.g. chemical composition

Definitions

• the present invention relates to a melt-extrudable material suitable for forming a transfer layer of photosensitive part of image forming device and to a transfer belt of photosensitive part formed by using the same.
• Fluorine-containing resins are excellent in chemical and thermal stability and in addition, surface lubricity, electrical properties, mechanical properties and abrasion resistance, and are widely used for a carrier of transfer material and an image forming part in the field of electrophotographic copying machine.
• a fluorine-containing resin composition is an electrically insulating material having a volume resistivity exceeding 10 16 ⁇ cm, and in a pressure roll and paper feeding roll inside an electrophotographic copying machine, causes troubles such as adherence of paper pieces thereto and adherence or scattering of toner due to static electricity.
• an electrically conductive substance to the fluorine-containing resin composition has been tried.
• the electrically conductive substance are carbon materials such as carbon black, graphite powder and carbon fiber, metal powder, and the like.
• an electrically conductive belt is used widely in an intermediate transfer device, transfer separation device, carrying device, charging device and developing device of electrophotographic copying machine, printer or facsimile machine.
• a usual electrically conductive belt is, for example, one produced by adding an electrically conductive carbon black to a thermoplastic resin. The resin is molded into films and the films are connected to make a belt. Also the resin is extrusion-molded into a tubular film, and this tubular film is cut crosswise in a horizontal direction. The resulting product is known as a seamless belt (JP-A-2-233765, JP-A-3-89357, JP-A-64-26439, etc.).
• thermoplastic resins are used depending on requirements.
• a fluorine-containing polymer has flame resistance, durability arid anti-filming property (toner-releasing property) which are more excellent than those of other thermoplastic resins, and therefore is widely used.
• durability arid anti-filming property toner-releasing property
• the electrically conductive belt when used as an intermediate transfer belt of a copying machine, etc., the belt is required to be electrically charged in order to electrostatically attract a toner onto a surface of the belt, and therefore high voltage is applied repeatedly to the belt by corona discharging. A resistance of the fluorine-containing polymer belt is lowered gradually by the applied high voltage and for that reason, an amount of toner transfer to the belt decreases, which has an adverse effect on an image.
• a specific range of conductivity is demanded in so-called semi-conductive rolls and belts such as a charge roll and belt, transfer roll and developing roll in an electrophotographic copying machine.
• a volume resistivity is required to be controlled in the range of from 10 8 to 10 13 ⁇ cm.
• a fluorine-containing resin composition having electric conductivity and non-sticking property which does not cause a drastic change in a resistance by an adding amount of the conductive substance, does not lower excellent properties inherent to the fluorine-containing resin such as chemical resistance and can minimize changes in mechanical properties such as an increase in a viscosity, surface roughness and non-sticking property.
• melt-extrudable material suitable for forming a transfer layer of a photosensitive part of image forming device, particularly the melt-extrudable material comprising a fluorine-containing resin which is excellent in non-sticking property, smoothness and strength and easy in controlling volume resistivity, and a transfer belt produced by using the melt-extrudable material.
• the present invention relates to the melt-extrudable material which is suitable for forming a transfer layer of a photosensitive part of image forming device and comprises a composition comprising (A) a filler and (B) a fluorine-containing thermoplastic resin and to the transfer belt produced by molding the melt-extrudable material; at least a part of the filler being fluorinated, and the composition giving a coating film having a surface volume resistivity of from 10 8 to 10 13 ⁇ cm, a water contact angle of not less than 96 degrees and a tensile strength of not less than 400 kgf/cm 2 at 25°C.
• the melt-extrudable material of the present invention comprises (A) a filler, at least a part of which is fluorinated and (B) a fluorine-containing thermoplastic resin.
• Examples of the preferred filler as the component (A), at least a part of which is fluorinated, are fluorinated carbon materials such as carbon black, carbon fiber, petroleum coke and graphite powder.
• a fluorinated carbon black obtained by fluorinating a carbon black particularly a fluorinated carbon black having a fluorine atom/carbon atom ratio F/C of not less than 0.1 and less than 1.0, particularly not less than 0.1 and less than 0.5 is preferred.
• F/C of the fluorinated carbon black of the component (A) is less than 0.1, an effect of fluorination is insufficient and the problems inherent to carbon material before fluorination remain unsolved, that is, controlling of conductivity is difficult because a rate of change in a resistance for an adding amount thereof is very big, a dispersion of the fluorinated carbon black becomes non-uniform due to growth of structure, and the obtained composition gets hard.
• F/C is not less than 1.0, a desired conductivity cannot be imparted to the composition.
• F/C is measured in the manner mentioned below.
• a fluorinated carbon black is wrapped together with a combustion improver Na 2 O 2 and a polyethylene film in a filter paper, followed by firing in a closed flask filled with oxygen.
• An amount of generated hydrogen fluoride is measured through usual method by using a fluoride ion meter (ION ANALYZER 901 available from Orion Corporation).
• a fluorine content is calculated from the obtained value.
• F/C is calculated from the obtained fluorine content.
• a major component of the fluorinated carbon black (A) is poly(carbon monofluoride).
• Preferred is a fluorinated carbon black obtained by fluorinating a carbon black having an average particle size of from 0.01 to 50 ⁇ m, preferably 0.01 to 1 ⁇ m with a fluorine gas.
• a fluorinated carbon black obtained by using a carbon material having an average particle size exceeding 50 ⁇ m, for example, petroleum coke, graphite powder or carbon fiber an amount thereof for imparting conductivity and non-sticking property to the resin must be increased and there is a tendency that there arise problems on the obtained composition such as an increase in a surface roughness, lowering of mechanical strength and non-uniform resistivity.
• a carbon material suitable for the fluorinated carbon black (A) is a carbon black having the above-mentioned average particle size.
• the usable carbon black are, for instance, commercially available ones such as a furnace black for rubber (for example, ASAHI #55 available from Asahi Carbon Co., Ltd., etc.), a channel black for coloration (for example, LEBEN 7000 available from Columbia Carbon Co., Ltd.), thermal black (SEVACARBON MT-C1 available from Columbia Carbon Co., Ltd.), and the like.
• the conductive carbon black is defined by the factors such as a small average particle size (average particle size: not more than 0.1 ⁇ m), a large surface area (N 2 surface area: not less than 50 m 2 /g), a developed structure (oil absorption: not less than 100 cc/g), a small content of impurities (ash content: less than 0.1 %) and an advanced graphitization.
• the conductive carbon black is widely used because conductivity can be imparted to the material with a relatively small amount thereof.
• Examples thereof are commercially available carbon blacks, for instance, KETJEN BLACK EC and KETJEN BLACK EC-600JD (The foregoing are available from Ketjen Black International, Inc.), BLACK PEARLS 2000, VULCAN XC-72 and CSX-99 (The foregoing are available from Cablack Co., Ltd.), DENKA BLACK (Denid Kagaku Kogyo Kabushiki Kaisha), CONDUCTEX 950 (Columbia Carbon Co., Ltd.), and the like.
• the fluorinated carbon black (A) used in the present invention is obtained by bringing those carbon materials into contact with fluorine gas at a temperature in a range of from 200° to 600°C, more preferably 300° to 500°C.
• a reaction temperature is lower than the above-mentioned range, there occur problems such that a fluorination reaction is slow, it is difficult to increase a degree of fluorination, thermal stability is not sufficient and properties inherent to the fluorinated carbon black such as non-sticking property and lubricity are not exhibited.
• the reaction temperature is higher than the above-mentioned range, a thermal decomposition reaction easily arises and yield of the obtained fluorinated carbon black is lowered. Also in some cases, a drastic thermal decomposition reaction may occur and result in an explosion. Therefore full attention must be paid to that.
• the fluorine gas used in the reaction may be diluted with an inert gas such as nitrogen, argon, helium or carbon tetrafluoride and may contain hydrogen fluoride.
• an inert gas such as nitrogen, argon, helium or carbon tetrafluoride and may contain hydrogen fluoride.
• reaction time and an amount of fluorine gas flow may be optionally adjusted depending on a reactivity of a starting carbon material with fluorine and a desired F/C (fluorine content).
• a feature of the present invention is to provide a fluorine-containing thermoplastic resin material capable of melt-extrusion molding.
• hitherto rubber materials such as a fluorine-containing rubber and silicone rubber have been used.
• materials mainly comprising those rubbers cannot be extrusion-molded.
• thermoplastic resin examples include copolymers of tetrafluoroethylene (TFE) with at least one ethylenically unsaturated monomer copolymerizable therewith (for example, olefins such as ethylene and propylene, halogenated olefins such as hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene and vinyl fluoride, perfluoro(alkyl vinyl ethers), and the like), polychlorotrifluoroethylene, polyvinylidene fluoride, and the like.
• TFE tetrafluoroethylene
• ethylenically unsaturated monomer copolymerizable therewith for example, olefins such as ethylene and propylene, halogenated olefins such as hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene and vinyl fluoride, perfluoro(alkyl
• a particularly preferred fluorine-containing thermoplastic resin is a fluorine-containing thermoplastic resin having hydrogen atom from the point that a high strength can be obtained and processability is excellent.
• ETFE ethylene-tetrafluoroethylene copolymer
• PVdF polyvinylidene fluoride
• vinylidene fluoride-hexafluoropropylene copolymer are preferred from the viewpoint of high strength and processability.
• fluorine-containing thermoplastic resins an effect of obtaining a composition having excellent heat resistance, non-sticking property, water- and oil-repellency, lubricity and chemical resistance is exhibited as compared with usual resins.
• thermoplastic resins such as polyether ether ketone, thermoplastic polyimide, polyethylene naphthalate, polybutylene naphthalate, polyether sulfone, polysulfone, polycarbonate, polyarylate, polybutylene terephthalate and polyether nitrile.
• a proportion of the component (A) to the component (B) is 1/99 to 20/80 (weight ratio, hereinafter the same). If the amount of the component (A) decreases, there is a tendency that an effect of adding the fluorinated carbon black is not obtained sufficiently, and if the amount is too much, there is a tendency that a mechanical strength such as a tensile strength is lowered.
• the above-mentioned non-fluorine-containing thermoplastic resin may be blended in a range not lowering the effect of the present invention.
• a feature of the melt-extrudable material of the present invention is such that a good extrusion-moldability can be obtained even without adding a plasticizer and a stable semi-conductivity can be obtained even without adding a surfactant. Therefore it is possible to eliminate an addition of a fluorine-containing surfactant and ester type plasticizer having a low electric resistance which have caused a problem with contamination because of bleeding thereof.
• composition of the present invention can be prepared, for example, by the following mixing methods.
• the resin, fluorinated carbon black and if necessary, a minimum of additives are mixed with a mixer such as V-blender, tumbler or Henschel mixer and then further mixed with a melt-kneader such as a two screw extruder to give pellets.
• a mixer such as V-blender, tumbler or Henschel mixer
• a melt-kneader such as a two screw extruder to give pellets.
• the so-obtained pellets are molded into a desired form, for example, belt, plate, film, and the like by using an extrusion-molding machine.
• the melt-extrudable material of the present invention has properties suitable as a molding material for a transfer layer of photosensitive part of image forming device.
• a tube or film obtained by melt-extrusion molding of the material of the present invention has the following properties.
• a surface roughness (Ra) is not more than 5 ⁇ m, especially not more than 0.5 ⁇ m.
• a smooth surface having a small surface roughness (Ra) is excellent from the viewpoint of a small amount of remaining toner and image forming property.
• a transfer belt which the present invention is directed to is subject to a large tension when rotated at high speed. Hitherto there was no transfer belt not only satisfying the above-mentioned properties (1), (2) and (4) but also giving a large tensile strength. Such a transfer belt is obtained only by the present invention.
• the material of the present invention can provide molded articles of various forms by melt-extrusion molding method, for example, molded articles in the form of film, tube, plate, belt, etc.
• a uniform and homogeneous melt-extrusion-molded article cannot be obtained unless a material therefor has excellent melt-moldability.
• a melt viscosity is increased significantly due to its structure and thus melt-kneading becomes insufficient and dispersion becomes non-uniform.
• melt flow rate (MFR) thereof which is one of indices for melt-moldability is in an allowable range (not less than 0.5 g/10 min, preferably not less than 0.7 g/ 10 min, ETFE: 297°C, PVdF: 230°C, load: 5 kg) and dispersibility (kneading property) as well as melt-moldability are good.
• the present invention also relates to the transfer belt of a photosensitive part of film forming device.
• Examples of the film forming device in the present invention are electrophotographic copying machine, facsimile machine, laser printer, and the like.
• the film forming device is not limited to them and encompasses a device for transferring a toner according to electrostatic copying.
• a photosensitive part of a fun forming device for example, art electrophotographic copying machine are usually used semi-conductive rolls such as a charge roll, developing roll and transfer belt (or roll).
• a transfer belt functions to transfer a toner image on a photosensitive drum to a transfer paper usually in such a manner that the endless transfer belt presses the transfer paper onto the photosensitive drum with three rolls.
• Such a transfer belt is a single endless belt (thickness: usually from 50 to 250 ⁇ m) or an endless belt comprising a heat resistant resin fabric and a transfer layer (thickness: from about 10 ⁇ m to about 50 ⁇ m) provided thereon.
• the transfer belt of the present invention can be applied to those conventional structures.
• melt-extrudable material of the present invention is also useful for a resistive layer such as a transfer roll, charge roll or developing roll in addition to the use for the transfer belt.
• Such rolls are obtained by forming a conductive elastic layer on a conductive substrate.
• a material for the conductive elastic layer is not limited particularly.
• the layer is formed by using a composition prepared by mixing a conductive powder, conductive fiber (carbon black, metal powder, carbon fiber, etc.), or the like to a synthetic rubber such as silicone rubber, ethylene propylene rubber, epichlorohydrin rubber, nitrile rubber or urethane rubber.
• the material to be used is one having a volume resistivity of not more than 10 5 ⁇ cm, preferably not more than 10 3 ⁇ cm and a rubber hardness (JIS A) in the range of 20 to 50 degrees, preferably 25 to 40 degrees.
• a plasticizer and surfactant for the purpose to adjust a resistivity and rubber hardness when mixing a conductive powder, etc. This is because bleeding of those chemicals arises with a lapse of time, which causes contamination of a surface of photosensitive and toner filming on a surface of the roll.
• a material of the conductive substrate is not limited particularly, and aluminum, an alloy mainly comprising aluminum or stainless steel can be used.
• melt-extrudable material of the present invention is made into a tubular form through usual melt-extrusion molding.
• the tube may be stretched or may have thermal shrinkability, but usually may have neither stretchability nor thermal shrinkability.
• a wall thickness of the tube need be in the range of from 0.01 to 0.15 mm. If the wall thickness is beyond the range, a preferred roll for photosensitive part cannot be obtained.
• the roll for photosensitive part of the present invention can be produced by a method of firstly putting the metallic core roll and the tube produced from the melt-extrudable material of the present invention in a cylindrical molded article so that a space is provided between the roll and the tube and the inner surface of the cylindrical molded article comes into contact with the outer surface of the tube, and then pouring a material for the conductive elastic layer into the above-mentioned space, and if necessary, carrying out vulcanizing. It is a matter of course that the roll covered with the tube has to be taken out of the cylindrical molded article at a necessary time.
• the inner surface of the tube may be subjected previously to etching treatment or primer treatment so that it is easily contacted to the rubber portion.
• the roll may be produced by previously making the conductive elastic layer and then covering the tube of the present invention on the surface of the conductive elastic layer. In that case, it is better to use a tube having thermal shrinkability. Thus there is no restriction in the production method of the roll.
• melt-extrudable material of the present invention is suitable for various rolls and belts of a photosensitive part of film forming device, particularly for a transfer belt which is required to have high strength.
• Part represents part by weight.
• Carbon black (DENKA BLACK available from Denki Kagaku Kogyo Kabushiki Kaisha, average particle size: 0.04 ⁇ m) was fluorinated to give a fluorinated carbon black having F/C of 0.1.
• a volume resistivity is measured with a resistance measuring cell (Resistivity Chamber R12702A) and a resistance meter (Digital Ultra-high Resistance Meter R8340A) which are available from ADVANTEST CORPORATION) according to JIS K 6911.
• a water contact angle is measured with a contact angle meter available from Kyowa Kaimen Kagaku Kabushiki Kaisha.
• a tensile strength is measured according to ASTM D 638.
• Measurement is made automatically on 2.5 mm surface of a sample at a pick-up speed of 0.3 mm/sec with a diamond pick-up having a needle end of 2 ⁇ mR by using a surface roughness meter (Surfcom 470A) available from Tokyo Seimitsu Kabushild Kaisha.
• the surface roughness Ra is a center line average height prescribed in JIS B 0601-1982.
• melt flow rate (MFR)(ETFE: 297°C, PVdF: 230°C, load: 5 kg) is measured according to ASTM D 3307 to examine melt-moldability of the melt-extrudable material of the present invention. The results are shown in Table 1.
• Pellets were obtained in the same manner as in Example 1 except that a fluorinated carbon black having F/C shown in Table 1 was used in an amount shown in Table 1, and then melt-extrusion-molded to give a film. Physical properties of the film were measured. The results are shown in Table 1.
• Pellets were obtained in the same manner as in Example 1 except that polyvinylidene fluoride (PVdF) was used instead of ETFE, and then melt-extrusion-molded to give a film. Physical properties of the film were measured. The results are shown in Table 1.
• PVdF polyvinylidene fluoride
• a film was produced in the same manner as in Example 1 except that only ETFE was melt-extrusion-molded without blending a fluorinated carbon black. Physical properties of the film were measured. The results are shown in Table 1.
• Example 2 Melt-extrusion molding was carried out in the same manner as in Example 1 except that a non-fluorinated carbon black (DENKA BLACK available from Denki Kagaku Kogyo Kabushiki Kaisha, average particle size: 0.04 ⁇ m) was used instead of a fluorinated carbon black in an amount shown in Table 1, to give a film. Physical properties of the film were measured. The results are shown in Table 1.
• DENKA BLACK available from Denki Kagaku Kogyo Kabushiki Kaisha, average particle size: 0.04 ⁇ m
• melt-extrudable material of the present invention is excellent in melt-moldability (MFR), and a variation of a volume resistivity is small even if an adding amount of fluorinated carbon black is changed (comparison between Example 1 and 2, 3 and 4, and 5 and 6, respectively).
• the melt-extrudable material gives a molded article which is suitable for a transfer belt or roll of photosensitive part, has enough strength and is excellent in non-sticking property (water contact angle) and smoothness (surface roughness).

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Electrostatic Charge, Transfer And Separation In Electrography (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=15043271

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (5)

Family Cites Families (10)

• 1999
  • 1999-04-26 JP JP2000548777A patent/JP3743288B2/ja not_active Expired - Fee Related
  • 1999-04-26 WO PCT/JP1999/002194 patent/WO1999059033A1/fr not_active Ceased
  • 1999-04-26 EP EP99917146A patent/EP1079282A4/fr not_active Withdrawn
  • 1999-04-26 KR KR1020007011660A patent/KR20010034795A/ko not_active Ceased

Also Published As

Similar Documents

Legal Events