JP6368656B2 - Intermediate transfer belt - Google Patents

Description

  The present invention relates to an intermediate transfer belt used in an electrophotographic image forming apparatus.

  An intermediate transfer belt is incorporated in an image forming apparatus such as a copying machine, a printer, or a printing machine that employs an electrophotographic system. In the image forming apparatus, each toner image formed for each color by a plurality of photoconductors is primarily transferred onto the belt surface of the intermediate transfer belt. The toner images of the respective colors superimposed by the primary transfer are secondarily transferred from the belt surface to a print medium such as paper.

  As an intermediate transfer belt having such a function, a resin base single layer formed in a cylindrical shape has been conventionally used. In recent years, in order to improve secondary transferability, an intermediate transfer belt having a two-layer structure in which a flexible and smooth rubber elastic layer made of acrylonitrile-butadiene rubber or the like is laminated on the outer periphery of a base layer has been used. Yes. A rubber elastic layer made of acrylonitrile-butadiene rubber or the like has high flexibility, but has a strong tackiness on the surface of the layer as it is. Therefore, in order to improve toner separation and toner cleaning properties, the middle of a three-layer structure in which a surface layer having a relatively high hardness and a smooth surface is formed on the surface of the rubber elastic layer by a resin such as an acrylic resin. Transfer belts are also known.

  Prior Patent Document 1 also discloses an intermediate transfer belt in which independent spherical resin particles are embedded in the belt surface at a predetermined embedding rate, thereby forming an uneven shape.

JP 2011-150059 A

  However, the above-described intermediate transfer belt having a two-layer structure or a three-layer structure has the following problems. That is, in the intermediate transfer belt, the toner image is pressed against the smooth belt surface by the photoconductor during the primary transfer. At this time, there is a problem in that stress is generated in the toner and the toner aggregates, and the aggregated toner partially falls off, thereby causing a phenomenon called “cold” where the primary transfer becomes insufficient. If a hollowing out phenomenon occurs during primary transfer, the image quality of the image forming apparatus deteriorates.

  In the intermediate transfer belt, a voltage is applied in order to transfer and receive toner on the belt surface. By applying this voltage, ozone is generated in the use atmosphere. The generated ozone deteriorates the belt surface. As a result, there is a problem that cracks occur on the belt surface when the belt is used. When cracks occur on the belt surface, the durability of the intermediate transfer belt is lowered, and as a result, the durability of the image forming apparatus is also lowered.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an intermediate transfer belt capable of suppressing a void phenomenon during primary transfer and capable of suppressing cracks on the belt surface due to ozone deterioration. is there.

One aspect of the present invention is an intermediate transfer belt used in an electrophotographic image forming apparatus,
It has a base layer formed in a cylindrical shape, a rubber elastic layer laminated on the outer periphery of the base layer, and a surface layer laminated on the outer periphery of the rubber elastic layer,
The surface layer has a matrix polymer containing hydrogenated acrylonitrile-butadiene rubber, and a large number of spherical fine particles filled in the matrix polymer.
The large number of spherical fine particles are present in the in-plane direction of the surface layer in a state of being stacked in the thickness direction of the surface layer,
The intermediate transfer belt is characterized in that the surface of the surface layer has surface irregularities formed by the matrix polymer being raised by the large number of spherical fine particles.

  In the intermediate transfer belt, a large number of spherical fine particles filled in a matrix polymer constituting the surface layer are spread in the in-plane direction of the surface layer while being stacked in the thickness direction of the surface layer. And the surface layer surface has the unevenness | corrugation formed by the matrix polymer protruding by these many spherical fine particles. Therefore, when the toner image is pressed onto the surface of the surface layer by the photoconductor during the primary transfer, the surface irregularities are deformed and the spherical fine particles arranged inside easily escape in the in-plane direction. As a result, the stress applied to the toner is relieved and the toners are less likely to agglomerate with each other, and it is possible to suppress the void phenomenon that has conventionally occurred during the primary transfer.

  Furthermore, the hydrogenated acrylonitrile-butadiene rubber (HNBR) used for the surface layer constituting the belt surface has hydrogenated double bonds in the acrylonitrile-butadiene rubber. Less ozone degradation. Therefore, the intermediate transfer belt can suppress cracks on the surface (belt surface) due to ozone degradation.

  Therefore, according to the present invention, it is possible to provide an intermediate transfer belt capable of suppressing a void phenomenon during primary transfer and suppressing a crack on the belt surface due to ozone deterioration.

FIG. 3 is an explanatory diagram schematically illustrating an intermediate transfer belt of Example 1. It is explanatory drawing which expanded and showed the II-II cross section of FIG. 1 typically. It is a laser microscope image of the surface layer surface of the intermediate transfer belt of Sample 1 in an experimental example.

  The intermediate transfer belt is used in an electrophotographic image forming apparatus. Examples of the image forming apparatus include an electrophotographic copying machine using a charged image, a printer, a facsimile machine, a multifunction machine, an on-demand printing machine, and the like.

  The intermediate transfer belt has a base layer formed in a cylindrical shape. The base layer can be mainly composed of a resin. Examples of the resin used for the base layer include polyamideimide, polyimide, polyethersulfone resin, fluorine-based resin, and polycarbonate resin. These can be used alone or in combination of two or more. Of these resins, polyimide and / or polyamideimide are preferable. In this case, since the rigidity of the base layer is increased, it is advantageous for improving the durability of the intermediate transfer belt.

The base layer material used for forming the base layer contains one or more various additives such as a conductive agent, a flame retardant, a crosslinking agent, a leveling agent, a filler, and an antioxidant, as necessary. Can do. Examples of the conductive agent include carbon-based conductive materials such as carbon black, carbon nanotube, and graphite, metal powder materials such as aluminum powder and stainless steel powder, conductive zinc oxide (c-ZnO), and conductive titanium oxide (c-TiO). ₂ ), electronic conductive agents such as conductive metal oxides such as conductive iron oxide (c-Fe ₃ O ₄ ) and conductive tin oxide (c-SnO ₂ ). These can be used alone or in combination of two or more. Further, the cylindrical diameter and thickness of the base layer can be appropriately determined according to the application (for example, the model and size of the image forming apparatus). The cylinder diameter of the base layer can be about 120 mm to 1000 mm, for example. The thickness of the base layer is preferably 30 to 200 μm, more preferably 40 to 130 μm, and still more preferably 60 to 90 μm.

  The intermediate transfer belt has a rubber elastic layer laminated on the outer periphery of the base layer. The rubber elastic layer material used for forming the rubber elastic layer may include one or more rubbers selected from the group consisting of hydrogenated acrylonitrile-butadiene rubber, acrylonitrile-butadiene rubber, and butadiene rubber. it can. In this case, the adhesion between the surface layer and the rubber elastic layer is improved, and the surface layer is difficult to peel from the rubber elastic layer. Further, it is easy to ensure the flexibility of the rubber elastic layer, which is advantageous for improving the secondary transferability. The above rubbers can be used after being crosslinked.

  The rubber elastic layer material preferably contains at least hydrogenated acrylonitrile-butadiene rubber. In this case, since the same material hydrogenated acrylonitrile-butadiene rubber is used for the surface layer and the rubber elastic layer, the adhesion between the surface layer and the rubber elastic layer is further improved, and the surface layer is further improved from the rubber elastic layer. It becomes more difficult to peel off. Moreover, since not only the surface layer but also the double bond in the rubber elastic layer is reduced, it is easy to suppress the ozone deterioration of the rubber elastic layer due to the ozone transmitted through the surface layer. Therefore, in this case, it is advantageous for improving the durability.

  In addition to the rubber such as hydrogenated acrylonitrile-butadiene rubber, the rubber elastic layer material can contain, for example, polyvalent isocyanate having two or more isocyanate groups in the molecule. In this case, when the rubber elastic layer is formed from a cured product of the rubber elastic layer material, the strength of the rubber elastic layer increases, which is advantageous for improving the durability of the rubber elastic layer.

  Examples of the polyvalent isocyanate include aliphatic, alicyclic or aromatic polyisocyanates or derivatives of these polyisocyanates such as isocyanurates, biurets and adducts. Can be exemplified by aliphatic, alicyclic or aromatic diisocyanates or derivatives of these diisocyanates such as isocyanurates, biurets and adducts.

  More specifically, polyisocyanates include hexamethylene diisocyanate (HDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), isophorone diisocyanate (IPDI), xylene diisocyanate (XDI), xylene diisocyanate (XDI). ), Hydrogenated xylene diisocyanate (H6XDI), hydrogenated xylene diisocyanate (H6XDI), diphenylmethane diisocyanate (MDI), diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), naphthalene diisocyanate (NDI), these isocyanurates, biurets, adak It can be exemplified derivatives body such like. These can be used alone or in combination of two or more. The “system” mentioned above is meant to comprehensively include polyisocyanates having the same base isocyanate, derivatives thereof such as isocyanurates, biurets and adducts. That is, for example, in the case of “hexamethylene diisocyanate type”, various polyisocyanates based on hexamethylene diisocyanate, derivatives thereof such as isocyanurate, biuret and adducts are included. The same applies to other cases.

  As the polyvalent isocyanate, hexamethylene diisocyanate, hexamethylene diisocyanate, or the like can be suitably used. In this case, since the elasticity of the rubber elastic layer is excellent, it is advantageous for improving secondary transferability.

  The rubber elastic layer material may contain at least a bifunctional polyol or the like in addition to a rubber such as hydrogenated acrylonitrile-butadiene rubber and a polyvalent isocyanate. In this case, a urethane bond is easily formed when the rubber elastic layer material is cured, and the recovery elastic modulus of the rubber elastic layer is easily improved. Therefore, the deformation recovery performance of the rubber elastic layer is improved, and when the rubber elastic layer is deformed, the rubber elastic layer quickly returns to the flat state. Therefore, in this case, the secondary transfer property is improved and it is easy to contribute to good image formation.

  The polyol can include polyether polyol, polycarbonate diol, polyester diol and the like. Of these, ether polyols are preferably used from the viewpoint of flexibility. Specific examples of the polyol include ethylene oxide, polyols such as 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 1,4-bis (hydroxymethyl) cyclohexane, and ethylene oxide. Examples thereof include compounds to which alkylene oxides such as propylene oxide and butylene oxide are added. These can be used alone or in combination of two or more. The alkylene oxide unit formed by alkylene oxide is preferably composed of a propylene oxide unit formed by propylene oxide. In this case, moderate hardness can be expressed, and the recovery elastic modulus of the rubber elastic layer can be easily improved.

  The rubber elastic layer material is made of a conductive agent, a flame retardant (organic flame retardant, inorganic flame retardant), a crosslinking agent, a crosslinking aid, a vulcanizing agent, a vulcanization accelerator, an acid acceptor, if necessary. One or more various additives such as a lubricant, a filler and a catalyst can be contained.

  The conductive agent may be either an ionic conductive agent or an electronic conductive agent, and may include both. The conductive agent is preferably an ionic conductive agent from the viewpoint of easily obtaining a uniform volume electric resistance. Specific examples of the ionic conductive agent include quaternary ammonium salts, phosphate esters, sulfonates, aliphatic polyhydric alcohols, aliphatic alcohol sulfates, ionic liquids, and the like. These can be used alone or in combination of two or more. In addition, as an electronic electrically conductive agent, what was mentioned above in description of a base layer can be illustrated.

  The thickness of the rubber elastic layer can be determined in consideration of flexibility, flame retardancy, warpage, wear resistance, usage, and the like. The thickness of the rubber elastic layer is preferably 10 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more, and even more preferably 80 μm or more. On the other hand, the thickness of the rubber elastic layer is preferably 400 μm or less, more preferably 300 μm or less, still more preferably 250 μm or less, and even more preferably 220 μm or less.

  The intermediate transfer belt has a surface layer laminated on the outer periphery of a rubber elastic layer. Here, the surface layer has a matrix polymer containing hydrogenated acrylonitrile-butadiene rubber and a large number of spherical fine particles filled in the matrix polymer. The spherical shape includes not only a true sphere but also a shape similar to a sphere. A spheroid with a flatness ratio of 50% or more is included in a spherical shape.

  In addition to the hydrogenated acrylonitrile-butadiene rubber, the matrix polymer can contain, for example, one or more of acrylonitrile-butadiene rubber and butadiene rubber. These can be used after being crosslinked. The matrix polymer is preferably composed of hydrogenated acrylonitrile-butadiene rubber. This is because cracks on the belt surface due to ozone deterioration are surely suppressed, and the ozone-resistant barrier function is easily improved.

  Many spherical fine particles are present in the in-plane direction in the surface layer in a state of being stacked in the thickness direction of the surface layer. And the surface layer has the surface unevenness | corrugation formed by the matrix polymer protruding by these many spherical fine particles on the surface. Accordingly, the intermediate transfer belt has a different configuration from that in which a large number of spherical fine particles are embedded on the surface of the surface layer at a predetermined embedding rate. In the intermediate transfer belt, a part of the large number of spherical fine particles may be exposed on the surface of the surface layer as long as the hollow-out phenomenon can be suppressed. Further, the intermediate transfer belt may include a portion where the spherical fine particles are not stacked in the thickness direction of the surface layer as long as the hollowing out phenomenon can be suppressed.

  Specific examples of the material of the spherical fine particles include organic materials such as resins and inorganic materials. As the spherical fine particles, preferably, spherical resin fine particles can be suitably used. In this case, the spherical fine particles in the surface layer easily escape in the in-plane direction during the primary transfer, and even if the surface layer is filled with a relatively large amount of spherical fine particles, the hardness of the surface layer does not become excessively large. It is advantageous for improving the next transfer property. Further, in this case, since it is easy to obtain spherical fine particles having a narrow particle size distribution, it is easy to obtain an intermediate transfer belt that easily exhibits an effect of suppressing the hollowing out phenomenon during primary transfer.

  More specifically, examples of the spherical fine particles include spherical (meth) acrylic resin fine particles, spherical urethane-based resin fine particles, and spherical polyamide-based resin fine particles. The spherical fine particles can be used alone or in combination of two or more. In addition, (meth) acryl is the meaning including both acryl and methacryl (henceforth abbreviate | omitting).

  In the intermediate transfer belt, the content of the spherical fine particles in the surface layer can be specifically in the range of 5 to 45% by volume, for example. In this case, in the surface layer, a large number of spherical fine particles are likely to be spread in the in-plane direction in the surface layer in a state of being stacked in the thickness direction of the surface layer. Therefore, surface irregularities due to the matrix polymer are easily formed on the surface of the surface layer, and it is possible to reliably suppress the hollowing out phenomenon during the primary transfer. The volume% is a value calculated from the bulk density of the spherical fine particles and the specific gravity of the matrix polymer with respect to 100 parts by mass of the matrix polymer. Specifically, volume% = volume of spherical fine particles / volume of matrix polymer × 100.

  The content of the spherical fine particles in the surface layer is preferably 8% by volume or more, more preferably 10% by volume or more, still more preferably 13.6% by volume or more, and even more preferably 15% by volume, from the viewpoint of suppressing the hollow-out phenomenon. % Or more, even more preferably 17% by volume or more, and most preferably 18% by volume or more. In addition, the content of the spherical fine particles in the surface layer is preferably 43% by volume or less, more preferably 40% by volume or less, and still more preferably 38 from the viewpoints of the flexibility of the surface layer, the filling property of the spherical fine particles, and securing of the matrix polymer. 0.1% by volume or less, even more preferably 30% by volume or less, even more preferably 25% by volume or less, and most preferably 21% by volume or less.

  In the intermediate transfer belt, specifically, the average particle diameter of the spherical fine particles can be, for example, in a range of 0.1 or more and less than 3 μm. In this case, surface irregularities having an appropriate size are easily secured on the surface of the surface layer to suppress the hollowing out phenomenon during the primary transfer, and excessively large surface irregularities are hardly formed on the surface of the surface layer. Therefore, in this case, for example, when the surface of the surface layer is cleaned by the blade member, an untransferred toner hardly occurs, and an intermediate transfer belt that is advantageous in improving the toner cleaning property can be obtained. The average particle size is the particle size when the volume-based cumulative frequency distribution measured by a laser diffraction / scattering particle size distribution measuring device (manufactured by JGC Corporation, “Microtrack MT3300EX”) shows 50% ( Diameter) d50.

  The average particle diameter of the spherical fine particles is preferably 0.2 μm or more, more preferably 0.3 μm or more, and still more preferably 0.4 μm or more, from the viewpoint of the formation of surface irregularities. The average particle diameter of the spherical fine particles is preferably 2 μm or less, more preferably 1.5 μm or less, still more preferably 1.3 μm or less, and even more preferably 1 μm or less, from the viewpoint of improving toner cleaning properties. Can do.

  In the intermediate transfer belt, the maximum height Rz defined in JIS B0601: 2001 on the surface of the surface layer can be about 1.0 to 1.4 μm. The reference length when measuring the maximum height Rz is 10 mm.

  Specifically, the surface layer can be formed using a surface layer material containing, for example, a matrix polymer containing hydrogenated acrylonitrile-butadiene rubber and a large number of spherical fine particles. If necessary, the surface layer material may contain the above-mentioned conductive agent (electronic conductive agent and / or ionic conductive agent), flame retardant (organic flame retardant and / or inorganic flame retardant), cross-linking agent, cross-linking aid, One or more additives such as a sulfurizing agent, a vulcanization accelerator, an acid acceptor, a lubricant, and a filler can be contained.

  The thickness of the surface layer is preferably 3 μm or more, more preferably 4 μm or more, further preferably 5 μm or more, and even more preferably 6 μm or more, from the viewpoints of spherical fine particle filling properties, surface unevenness forming properties, surface slipperiness, and the like. can do. On the other hand, the thickness of the surface layer is preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 15 μm or less, from the viewpoints of suppressing increase in the friction coefficient of the belt surface and suppressing permanent distortion.

  The surface of the surface layer may be subjected to a light irradiation treatment or a surface treatment with a surface treatment liquid from the viewpoint of improving toner releasability. Specifically, the light irradiation treatment can be an ultraviolet irradiation treatment. As the surface treatment liquid, specifically, a surface treatment liquid containing a chlorine-containing compound, a surface treatment liquid containing a fluorine-containing compound, a surface treatment liquid containing isocyanate, and the like can be applied.

  In addition, each structure mentioned above can be arbitrarily combined as needed, in order to acquire each effect etc. which were mentioned above.

  Hereinafter, the intermediate transfer belt of the embodiment will be described with reference to the drawings.

Example 1
The intermediate transfer belt of Example 1 will be described with reference to FIGS. As shown in FIGS. 1 and 2, the intermediate transfer belt 1 of this example is used in an electrophotographic image forming apparatus. The intermediate transfer belt 1 includes a base layer 2 formed in a cylindrical shape, a rubber elastic layer 3 stacked on the outer periphery of the base layer 2, and a surface layer 4 stacked on the outer periphery of the rubber elastic layer 3. That is, the intermediate transfer belt 1 has a three-layer structure in which the rubber elastic layer 3 is laminated along the outer peripheral surface of the base layer 2 and the surface layer 4 is laminated in order along the outer peripheral surface of the rubber elastic layer 3. In FIG. 1, a detailed belt layer configuration is omitted.

  In this example, specifically, the base layer 2 is formed of polyimide or polyamideimide. The rubber elastic layer 3 includes one or more rubbers selected from the group consisting of hydrogenated acrylonitrile-butadiene rubber, acrylonitrile-butadiene rubber, and butadiene rubber, and a multi-layer having two or more isocyanate groups in the molecule. It is formed using a rubber elastic layer material containing a polyvalent isocyanate. The base layer 2 has conductivity by containing an electronic conductive agent. The rubber elastic layer 3 has conductivity by containing an ionic conductive agent.

  Here, the surface layer 4 has a matrix polymer 41 containing hydrogenated acrylonitrile-butadiene rubber, and a large number of spherical fine particles 42 filled in the matrix polymer 41. As shown in FIG. 2, a large number of spherical fine particles 42 are spread in the in-plane direction of the surface layer 4 while being stacked in the thickness direction of the surface layer 4. And the surface layer 4 has the surface unevenness | corrugation 43 which the matrix polymer 41 protruded by many spherical fine particles 42 on the surface.

  In this example, specifically, the content of the spherical fine particles 42 in the surface layer 4 is in the range of 5 to 45% by volume. Further, the average particle diameter of the spherical fine particles 42 is set in a range of 0.1 or more and less than 3 μm. Specifically, the surface layer 4 is formed using a surface layer material containing a matrix polymer containing hydrogenated acrylonitrile-butadiene rubber and a large number of spherical fine particles. The surface layer 4 has conductivity by containing an electronic conductive agent.

  Hereinafter, a plurality of intermediate transfer belt samples having different configurations were prepared and evaluated. An experimental example will be described.

(Experimental example)
<Preparation of base layer material>
Polyamideimide (PAI) (manufactured by Toyobo Co., Ltd., “Vilomax HR-16NN”) or polyimide (PI) (manufactured by Shin Nippon Rika Co., Ltd., “Rika Coat EN-20”) and an electronic conductive agent (carbon black) ) (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.) By mixing 10 parts by mass with 800 parts by mass of N-methyl-2-pyrrolidone (NMP), a PAI-based substrate material and a PI-based substrate layer The material was prepared.

<Preparation of rubber elastic layer material>
The following were prepared as materials used for the rubber elastic layer material.
Hydrogenated acrylonitrile-butadiene rubber (HNBR) (manufactured by Nippon Zeon Co., Ltd., “Zetpol 1020”)
・ Acrylonitrile-butadiene rubber (NBR) (Nippon Zeon, “Nipol DN3335”)
・ Butadiene rubber (BR) (manufactured by Nippon Zeon Co., Ltd., “Nipol BR1220”)
・ Vulcanization accelerator (1) (manufactured by Sanshin Chemical Co., Ltd., “Sunseller DM”)
・ Vulcanization accelerator (2) (manufactured by Sanshin Chemical Co., Ltd., “Suncellor TT”)
・ Vulcanizing agent (sulfur powder) (manufactured by Tsurumi Chemical Industry Co., Ltd., “Sulfur PTC”)
・ Lubricant (stearic acid) (manufactured by NOF Corporation, "Stearic acid cherry")
・ Acid-accepting agent (zinc oxide) (manufactured by Shodo Chemical Industry Co., Ltd., “Zinc oxide 2 types”)
・ Polyisocyanate (trimethylolpropane adduct of hexamethylene diisocyanate) (Tosoh Corp., “Coronate HL”)
・ Organic flame retardant (phosphazene derivative) (Fushimi Pharmaceutical Co., Ltd., “Ravitor FR-110”)
・ Inorganic flame retardant (aluminum hydroxide) (manufactured by Showa Denko KK, “Hijilite H-42M”)
・ Ionic conductive agent (tetrabutylammonium bromide: TBAB) (Fuji Junyaku Co., Ltd.)

  Each material shown in Table 2 to be described later is mixed in cyclohexanone so as to have a solid content of 25% by mass at each compounding ratio shown in Table 2, and mixed to obtain a liquid for each rubber elastic layer. The material was prepared.

<Preparation of surface layer material>
The following were prepared as materials used for the surface layer material.
・ Hydrogenated acrylonitrile-butadiene rubber (HNBR)
・ The above acrylonitrile-butadiene rubber (NBR)
・ Acrylic resin (Negami Kogyo Co., Ltd., “Paracron W-248E”)
・ Vulcanization accelerator (1)
・ The above vulcanization accelerator (2)
・ The above vulcanizing agent (sulfur powder)
・ Lubricant (stearic acid)
・ Acid acceptor (zinc oxide)
・ The above polyisocyanate (hexamethylene diisocyanate trimethylolpropane adduct)
・ The above organic flame retardants (phosphazene derivatives)
・ The above electronic conductive agent (carbon black)
Spherical fine particles (1) (spherical cross-linked acrylic resin fine particles, average particle size 0.8 μm) (“MX-80H3wt” manufactured by Soken Chemical Co., Ltd.)
Spherical fine particles (2) (spherical cross-linked acrylic resin fine particles, average particle size 1.0 μm) (“MX-100” manufactured by Soken Chemical Co., Ltd.)
・ Spherical fine particles (3) (spherical cross-linked acrylic resin fine particles, average particle size 0.4 μm)
The spherical fine particles (3) were obtained by classifying the spherical fine particles (1) using a classifier (manufactured by Matsubo, “Elbow Jet Classifier LABO”).
Spherical fine particles (4) (spherical cross-linked acrylic resin fine particles, average particle size: 3.0 μm) (“MX-300” manufactured by Soken Chemical Co., Ltd.)
・ Non-spherical fine particles (porous silica fine particles, average particle size 0.8 μm)
Non-spherical fine particles were obtained by classifying porous silica fine particles (average particle size: 3.0 μm, manufactured by Fuji Silysia Chemical Co., Ltd., “Silicia 430”) using the classifier.

  Each material shown in Table 2 to be described later is mixed in cyclohexanone so as to have a solid content of 10% by mass at each compounding ratio shown in Table 2, and mixed to obtain each liquid surface layer material. Prepared.

<Preparation of intermediate transfer belt sample>
An aluminum cylindrical mold was prepared as a substrate. In addition, a dispenser (liquid quantitative discharge device) having one nozzle was prepared. The nozzle of this dispenser is a needle nozzle having an inner diameter φ = 1 mm. Next, the predetermined base layer material, rubber elastic layer material, and surface layer material prepared above are accommodated in separate air pressure tanks, and the clearance between the outer peripheral surface of the mold and the nozzle is set to 1 mm. The mold and nozzle were set. Next, the nozzle for discharging the base layer material is moved downward in the axial direction at a moving speed of 1 mm / sec while rotating around the axis at a rotation speed of 200 rpm in a state where the mold is vertical, and an air pressurization tank The base layer material was pumped to the nozzle by applying a pressure of 0.4 MPa to the nozzle, and the base layer material was discharged from the nozzle, and was applied spirally on the outer peripheral surface of the mold. This formed the whole coating film which consists of a continuous body of a helical coating film. Subsequently, the formed whole coating film was subjected to heat treatment under the condition that the temperature was raised from room temperature to 250 ° C. in 2 hours and held at 250 ° C. for 1 hour. Thereby, the base layer (thickness 80 micrometers) formed in the cylinder shape was formed on the outer peripheral surface of a metal mold | die.

  Next, the nozzle for discharging a predetermined rubber elastic layer material is moved downward in the axial direction at a moving speed of 1 mm / sec while rotating the mold on which the base layer is formed around the axis at a rotation speed of 200 rpm. In addition, the pressure of 0.8 MPa is applied to the air pressure tank, the rubber elastic layer material is pumped to the nozzle, the rubber elastic layer material is discharged from the nozzle, and the surface of the base layer on the outer peripheral surface of the mold is spiral. Coated. This formed the whole coating film which consists of a continuous body of a helical coating film. Next, the formed whole coating film was subjected to heat treatment under the condition that the temperature was raised from room temperature to 170 ° C. in 3 hours and kept at 170 ° C. for 30 minutes. Thereby, a rubber elastic layer (thickness: 200 μm) was laminated along the outer peripheral surface of the base layer.

  Next, a nozzle for discharging a predetermined surface layer material is moved downward in the axial direction at a moving speed of 1 mm / sec while rotating the mold on which the rubber elastic layer is formed about the axis at a rotation speed of 100 rpm. At the same time, a pressure of 0.8 MPa is applied to the air pressure tank, the surface layer material is pumped to the nozzle, the surface layer material is discharged from the nozzle, and is spirally applied to the surface of the rubber elastic layer on the outer peripheral surface of the mold. Worked. This formed the whole coating film which consists of a continuous body of a helical coating film. Next, the formed whole coating film was subjected to heat treatment under the condition that the temperature was raised from room temperature to 170 ° C. in 30 minutes and held at 170 ° C. for 30 minutes. Thereby, a surface layer (thickness 15 μm) was laminated along the outer peripheral surface of the rubber elastic layer.

In this example, an ultraviolet ray irradiator (“UB031-2A / BM” (mercury lamp type) manufactured by Eye Graphics Co., Ltd.) is used while rotating the mold on which the surface layer is formed around the axis at a rotational speed of 60 rpm. The surface layer surface was irradiated with ultraviolet rays under the conditions of an irradiation intensity of 120 mW / cm ² , an irradiation time of 30 seconds, and a distance between the light source and the surface layer surface of 100 mm, and the surface layer was subjected to UV treatment. However, the sample 10 using an acrylic resin for the surface layer is not subjected to the UV treatment.

  Next, high-pressure air was blown between one end edge of the base layer and the outer peripheral surface of the mold, and the mold was extracted. Thus, the intermediate transfer belts of Sample 1 to Sample 12 were produced.

  When the cross section perpendicular to the surface of the intermediate transfer belt of Samples 1 to 9 was observed with a scanning electron microscope, a large number of spherical fine particles filled in the matrix polymer constituting the surface layer were stacked in the thickness direction of the surface layer. It was confirmed that it was spread in the in-plane direction of the surface layer. In addition, when the surface of the surface layer was observed with a laser microscope, as shown in FIG. 3, almost no spherical fine particles exposed on the surface of the surface layer were seen, and the matrix polymer was formed on the surface of the surface layer by a large number of spherical fine particles. Loose surface irregularities formed by bulging were confirmed.

<Primary transfer properties>
Each of the produced intermediate transfer belts is incorporated as an intermediate transfer belt of a color printer that employs an electrophotographic system ("MICROLINE VINCI C941dn" manufactured by Oki Data Co., Ltd.) to form a solid pattern fine line (line width: 0.5 mm). The toner image for this purpose was primarily transferred onto the surface of the intermediate transfer belt. Thereafter, the primary transferred toner image was observed with a microscope. A case where no toner dropout portion was observed in the toner image was determined as “A” because no hollowing out phenomenon occurred. When the toner image was confirmed to have a part where the agglomerated toner dropped out, it was determined as “C” because the hollowing out phenomenon occurred.

<Ozone resistance>
Each of the produced intermediate transfer belts was wound between a driving side roller having a diameter of 10 mm and a driven side roller having a diameter of 10 mm, which the rotation driving device has. At this time, the tension applied to the intermediate transfer belt of the sample was adjusted to 2 kgf on one side. Then, the sample intermediate transfer belt was rotated for 50 hours at a rotation speed of 40 rpm while being exposed to an air atmosphere having an ozone concentration of 5 ppm by mass. Then, the presence or absence of cracks on the surface of the surface layer, which is the surface of the belt, was confirmed in the stretched state. When no crack was confirmed with a 100 magnification microscope, it was designated as “A” because cracks on the belt surface due to ozone degradation were suppressed. When cracks were confirmed with a 100 magnification microscope, the cracks on the belt surface due to ozone deterioration were not suppressed and “C” was assigned.

<Adhesion>
The produced intermediate transfer belt was left in an environment of 40 ° C. × 95% RH for 1 week. Thereafter, the adhesion between the surface layer and the rubber elastic layer in each intermediate transfer belt was examined by a cross-cut tape test in accordance with JIS K5400. Specifically, using a cutter knife (“Small blade” manufactured by Olfa, Inc.) on the surface of the surface layer, after drawing 11 notches reaching the rubber elastic layer at an interval of 1 mm, the direction of 90 ° was changed and further 11 I drew a book. Thereby, 100 square grids were formed on the surface of the surface layer. Next, an adhesive tape (manufactured by 3M, “PTFE tape”) (width 25 mm) was applied to the grid so as to adhere to a length of about 50 mm, and then a 5 kg load was applied on the adhesive tape over 5 minutes. By allowing it to stand, the adhesive tape was sufficiently adhered to the grid. Next, the adhesive tape was peeled off instantaneously while holding the edge of the adhesive tape and keeping the adhesive tape at a right angle to the surface of the surface layer. And the adhesive tape side was confirmed and as shown in Table 1, it evaluated in six steps from 0-5. Specifically, the case where no lattice surface layer adhered to the adhesive tape and the adhesive tape did not change was defined as “5”. Moreover, the case where the surface layer adhered to the adhesive tape according to the degree shown in Table 1 was designated as “4”, “3”, “2”, “1”, or “0”.

<Cleanability>
The intermediate transfer belt of Sample 1 to Sample 9 is incorporated as an intermediate transfer belt of a color printer that employs an electrophotographic method (“MICROLINE VINIC C941dn” manufactured by Oki Data Corporation). Thus, the surface of the surface layer, which is the belt surface, was cleaned. Then, the surface layer surface was confirmed visually. The case where there was no toner scraping residue was designated as “A” for excellent cleaning properties. In addition, although it was within the allowable range, a case where a slight amount of toner scraping was observed was defined as “B”.

  Tables 2 and 3 summarize the detailed configuration and evaluation results of each intermediate transfer belt.

  According to the above results, the following can be understood. That is, the intermediate transfer belt of the sample 10 has surface irregularities formed by non-spherical fine particles added to the acrylic resin on the surface layer. For this reason, the intermediate transfer belt of the sample 10 does not sufficiently relax the stress applied to the toner when the toner image is pressed against the surface of the surface layer by the photoconductor during the primary transfer, and can suppress the void phenomenon. There wasn't. This is presumably because the non-spherical fine particles are difficult to escape in the in-plane direction in the surface layer because the non-spherical fine particles are used. Moreover, since the acrylic resin is hard, it is also considered that there was little deformation of the surface unevenness.

  Further, in the intermediate transfer belt of Sample 11, the matrix polymer constituting the surface layer is acrylonitrile-butadiene rubber, and the surface layer contains many double bonds due to acrylonitrile-butadiene rubber. Therefore, when the surface layer was exposed to ozone, the double bond in the surface layer was cut by ozone, and cracks due to ozone degradation occurred. Further, in the intermediate transfer belt of sample 11, as in the intermediate transfer belt of sample 10, the surface irregularities on the surface of the surface layer are formed by non-spherical fine particles, so that the hollowing out phenomenon cannot be suppressed.

  Further, in the intermediate transfer belt of Sample 12, the matrix polymer constituting the surface layer is acrylonitrile-butadiene rubber. The surface layer does not contain spherical fine particles. That is, the surface of the surface layer is smooth without fine surface irregularities due to spherical fine particles. For this reason, the intermediate transfer belt of the sample 12 was not able to suppress both the void phenomenon during the primary transfer and the crack on the belt surface due to ozone deterioration.

  On the other hand, in the intermediate transfer belts of Sample 1 to Sample 9, a large number of spherical fine particles filled in the matrix polymer constituting the surface layer are spread in the in-plane direction of the surface layer while being stacked in the thickness direction of the surface layer. doing. And the surface layer surface has the unevenness | corrugation formed by the matrix polymer protruding by these many spherical fine particles. Therefore, when the toner image is pressed onto the surface of the surface layer by the photoconductor during the primary transfer, the surface irregularities are deformed and the spherical fine particles arranged inside easily escape in the in-plane direction. As a result, the stress applied to the toner is relieved, the toners are less likely to agglomerate, and the void phenomenon during primary transfer can be suppressed.

  Also, the hydrogenated acrylonitrile-butadiene rubber used for the surface layer constituting the belt surface has few double bonds cut by ozone because the double bonds in the acrylonitrile-butadiene rubber are hydrogenated. Hard to deteriorate. Therefore, the intermediate transfer belts of Sample 1 to Sample 9 can suppress cracks on the surface layer due to ozone degradation.

  Further, when the intermediate transfer belts of Sample 1 to Sample 9 are compared, the following can be understood.

  In the intermediate transfer belts of Sample 1 to Sample 9, the rubber elastic layer material used for forming the rubber elastic layer is selected from the group consisting of hydrogenated acrylonitrile-butadiene rubber, acrylonitrile-butadiene rubber, and butadiene rubber. Contains seeds or two or more rubbers. Therefore, the intermediate transfer belts of Sample 1 to Sample 9 have high adhesion between the surface layer and the rubber elastic layer. In particular, Sample 1, Sample 4 to Sample 9 use hydrogenated acrylonitrile-butadiene rubber of the same material for the surface layer and the rubber elastic layer. Therefore, Sample 1, Sample 4 to Sample 9 have even higher adhesion between the surface layer and the rubber elastic layer.

  The intermediate transfer belts of Sample 1 to Sample 8 have an average particle diameter of spherical fine particles of less than 0.1 to 3 μm. For this reason, surface irregularities having an appropriate size are secured on the surface of the surface layer in order to suppress the hollowing out phenomenon during the primary transfer, while excessively large surface irregularities are hardly formed on the surface of the surface layer. Therefore, when the surface of the intermediate transfer belt of Samples 1 to 8 is cleaned by the cleaning blade, the toner is hardly scraped off and has excellent toner cleaning properties.

  As mentioned above, although the Example of this invention was described in detail, this invention is not limited to the said Example, A various change is possible within the range which does not impair the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Intermediate transfer belt 2 Base layer 3 Rubber elastic layer 4 Surface layer 41 Matrix polymer 42 Spherical fine particle 43 Surface unevenness

Claims (4)

An intermediate transfer belt used in an electrophotographic image forming apparatus,
It has a base layer formed in a cylindrical shape, a rubber elastic layer laminated on the outer periphery of the base layer, and a surface layer laminated on the outer periphery of the rubber elastic layer,
The surface layer has a matrix polymer containing hydrogenated acrylonitrile-butadiene rubber, and a large number of spherical fine particles filled in the matrix polymer.
The large number of spherical fine particles are present in the in-plane direction of the surface layer in a state of being stacked in the thickness direction of the surface layer,
An intermediate transfer belt having surface irregularities formed on the surface of the surface layer by the matrix polymer being raised by the large number of spherical fine particles.   2. The intermediate transfer belt according to claim 1, wherein the content of the spherical fine particles in the surface layer is in the range of 5 to 45% by volume.   3. The intermediate transfer belt according to claim 1, wherein an average particle diameter of the spherical fine particles is in a range of 0.1 to less than 3 μm.   The rubber elastic layer material used for forming the rubber elastic layer includes one or more rubbers selected from the group consisting of hydrogenated acrylonitrile-butadiene rubber, acrylonitrile-butadiene rubber, and butadiene rubber. The intermediate transfer belt according to any one of claims 1 to 3.