JP7031305B2 - Intermediate transfer belt and image forming device using it - Google Patents

Description

The present invention relates to an intermediate transfer belt and an image forming apparatus using the intermediate transfer belt.

Conventionally, seamless belts have been used as members in electrophotographic apparatus for various purposes. In particular, in recent full-color electrophotographic equipment, an intermediate transfer belt method is used in which developed images of four colors of yellow, magenta, cyan, and black are once color-superposed on an intermediate transfer belt and then collectively transferred to a transfer medium such as paper. Is used.

Such an intermediate transfer belt method has been used in a system using a four-color developer for one photoconductor, but has a drawback that the printing speed is slow. Therefore, as high-speed printing, a quadruple tandem method is used in which photoconductors are arranged for four colors and each color is continuously transferred to paper. However, with this method, it is very difficult to match the position accuracy of superimposing each color image due to fluctuations due to the paper environment and the like, which causes a color shift image. Therefore, in recent years, it has become mainstream to adopt the intermediate transfer method as the quadruple tandem method.

Under such circumstances, even in the intermediate transfer belt, the required characteristics (high-speed transfer, position accuracy) are stricter than before, and it is necessary to satisfy the characteristics corresponding to these requirements. There is. In particular, for position accuracy, it is required to suppress fluctuations due to deformation such as elongation of the belt itself due to continuous use. Further, the intermediate transfer belt is laid out over a wide area of the apparatus, and is required to be flame-retardant because a high voltage is applied for transfer. In order to meet such demands, polyimide resins, polyamide-imide resins and the like, which are high elastic modulus and high heat resistance resins, are mainly used as intermediate transfer belt materials.

However, since the intermediate transfer belt made of polyimide resin has high strength and high surface hardness, high pressure is applied to the toner layer when transferring the toner image, and the toner is locally aggregated to form a part of the image. So-called hollow images that are not transferred may occur. Further, since the contact followability with the contact member in the transfer portion such as a photoconductor or paper is inferior, a partial poor contact portion (void) may occur in the transfer portion, and transfer unevenness may occur.

In recent years, images are often formed on various types of paper using full-color electrophotographic, and not only ordinary smooth paper, but also recycled paper and embossed paper, which have slipperiness and high smoothness such as coated paper, are used. Rough surface materials such as Japanese paper and kraft paper are increasingly being used. It is important to have the ability to follow papers with different surface textures, and if the followability is poor, unevenness of unevenness in the unevenness of the paper and unevenness of color tone will occur. In order to solve this problem, various intermediate transfer belts in which an elastic layer in which a flame retardant is mixed with a relatively flexible rubber is laminated on a base layer have been proposed. However, rubber and flame retardants are easily affected by temperature and humidity, and the environmental fluctuation of resistance tends to be large. Therefore, there is a problem that the image density differs between the high temperature and high humidity environment and the low temperature and low humidity environment.

Patent Document 1 proposes an intermediate transfer belt in which red phosphorus and aluminum hydroxide are blended with rubber to achieve both flame retardancy and flexibility. However, the resistance difference between the high temperature and high humidity environment and the normal temperature and humidity environment is more than one digit, and the image quality required in recent years has not been reached.

The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide an intermediate transfer belt having high flame retardancy and having a stable image density even when the temperature and humidity change.

The above problem is solved by the following configuration 1).
1) An intermediate transfer belt on which a toner image obtained by developing a latent image formed on an image carrier with toner is transferred.
The intermediate transfer belt has a laminated structure including a base layer and an elastic layer containing spherical fine particles and having an uneven shape due to the spherical fine particles.
The elastic layer contains a phosphorus compound, a metal hydrate and a clay mineral, and contains acrylic rubber or hydrogenated nitrile rubber.
An intermediate transfer belt characterized by that.

According to the present invention, it is possible to provide an intermediate transfer belt having high flame retardancy and having a stable image density even when the temperature and humidity change.

It is sectional drawing which shows an example of the layer structure of the intermediate transfer belt of this invention. It is a top view of the intermediate transfer belt of FIG. It is a figure which shows the shape of a spherical fine particle schematically. It is a figure which shows the shape of a spherical fine particle schematically. It is a figure which shows the shape of a spherical fine particle schematically. It is a schematic diagram which shows an example of the method of applying spherical fine particles to an elastic layer. It is a schematic diagram of the main part which shows an example of the image forming apparatus of this invention. It is a schematic diagram of the main part which shows another example of the image forming apparatus of this invention.

Seamless belts are used for some members in electrophotographic equipment, and there is an intermediate transfer body (intermediate transfer belt) as one of the important members that require electrical characteristics. Hereinafter, the intermediate transfer belt of the present invention will be described.

The intermediate transfer belt of the present invention can be a seamless belt, which is a plurality of color toner developments sequentially formed on an intermediate transfer belt type electrophotographic apparatus [so-called image carrier (for example, photoconductor drum). It is suitably equipped as an intermediate transfer belt in a device of a system in which images are sequentially superposed on an intermediate transfer belt to perform primary transfer, and the primary transfer images are collectively transferred to a recording medium.

FIG. 1 is a cross-sectional view showing an example of the layer structure of the intermediate transfer belt of the present invention, and FIG. 2 is a plan view of the intermediate transfer belt of FIG.
In the intermediate transfer belt of FIG. 1, a flexible elastic layer 12 is laminated on a rigid base layer 11 that can obtain relatively flexibility, and a part of spherical fine particles 13 is exposed on the outermost surface thereof, and the elastic layer is formed. A concave-convex shape is given to 12. In a preferred embodiment, as shown in FIGS. 1 and 2, some or all of the spherical fine particles 13 are independently embedded in a single state in the thickness direction of the elastic layer 12, whereby the surface of the elastic layer 12 is formed. It has an uneven shape. In the form shown in FIGS. 1 and 2, there is almost no overlap of the spherical fine particles 13 in the thickness direction and / or the plane direction of the elastic layer 12, and there is almost no complete burial of the spherical fine particles 13 in the elastic layer 12.

<Base layer>
First, the base layer 11 will be described. The base layer 11 contains a resin, and examples thereof include a resin containing a filler (or an additive) for adjusting the electric resistance, that is, a so-called electric resistance adjusting material.
As such a resin, for example, a fluororesin such as PVDF or ETFE, a polyimide resin or a polyamide-imide resin is preferable from the viewpoint of flame retardancy, and particularly from the viewpoint of mechanical strength (high elasticity) and heat resistance. Polyimide resin or polyamide-imide resin is suitable.

Examples of the electric resistance adjusting material include metal oxides, carbon black, ionic conductive agents, and conductive polymer materials. Examples of the metal oxide include zinc oxide, tin oxide, titanium oxide, zirconium oxide, aluminum oxide, silicon oxide and the like. Further, in order to improve the dispersibility, the metal oxide may be surface-treated in advance. Examples of carbon black include Ketjen black, furnace black, acetylene black, thermal black, gas black and the like. Examples of the ionic conductive agent include tetraalkylammonium salt, trialkylbenzylammonium salt, alkylsulfonate, alkylbenzenesulfonate, alkylsulfate, gluserine fatty acid ester, sorbitan fatty acid ester, polyoxyethylenealkylamine, and polyoxyethylene fat. Examples thereof include alcohol esters, alkyl betaines, lithium perchlorate and the like, and these may be used in combination.
The electrical resistance adjusting material in the present invention is not limited to the above-mentioned exemplified compound.
In addition, the coating liquid used in the production of the intermediate transfer belt of the present invention further contains additives such as dispersion aids, reinforcing materials, lubricants, heat conductive materials, and antioxidants, if necessary. You may.

When used for a seamless belt suitably equipped as the intermediate transfer belt, the resistance values are preferably 1 × 10 ⁸ [Ω / □] to 1 × 10 ¹³ [Ω / □] for surface resistance and 1 for volume resistance. It is preferable to contain an electric resistance adjusting material such as carbon black so as to have × 10 ⁸ [Ω · cm] to 1 × 10 ¹¹ [Ω · cm]. The amount of the electric resistance adjusting material added should be set to an amount that does not deteriorate the electrical characteristics (surface resistance and volume resistance) and can obtain mechanical strength to the extent that the film is not fragile and easily cracked.

The thickness of the base layer 11 is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30 μm to 150 μm, more preferably 40 μm to 120 μm, and particularly preferably 50 μm to 80 μm. When the thickness of the base material layer is 30 μm or more, cracks are unlikely to occur and the belt can be suppressed from tearing, and when the thickness is 150 μm or less, the belt due to bending can be suppressed from cracking. Further, it is advantageous in terms of durability that the thickness of the base layer is in the particularly preferable range. It is preferable that the base layer 11 has as little film thickness unevenness as possible in order to improve running stability.

The thickness of the base layer 11 can be measured by, for example, a contact type or eddy current type film thickness meter, and the cross section of the film can also be measured by a scanning electron microscope (SEM).

In the case of carbon black, for example, the content of the electric resistance adjusting material in the present invention is, for example, 10 to 25 wt%, preferably 15 to 25 wt% with respect to the total solid content in the coating liquid for forming the base layer 11. It is 20 wt%. When a metal oxide is used, its content is, for example, 1 to 50 wt%, preferably 10 to 30 wt%, based on the total solid content in the coating liquid. By adopting the content of the electric resistance adjusting material as described above, the uniformity of the resistance value is improved, and the fluctuation of the resistance value with respect to an arbitrary potential is reduced. In addition, the mechanical strength of the intermediate transfer belt is improved, which is preferable in actual use.

As the polyimide and polyamide-imide in the present invention, general-purpose products from manufacturers such as Toray Dupont, Ube Industries, Shin Nihon Rika, JSR, Unitika, IST, Hitachi Kasei Kogyo, Toyo Spinning Co., Ltd., and Arakawa Chemical Co., Ltd. were obtained. Can be used.

<Elastic layer>
Next, the elastic layer 12 laminated on the base layer 11 will be described. As the material constituting the elastic layer 12, a general-purpose resin, elastomer, rubber or the like can be used, but a material having sufficient flexibility (elasticity) to sufficiently exhibit the effects of the present invention is used. It is preferable to use an elastomer material or a rubber material.
Examples of the elastomer material include polyester-based, polyamide-based, polyether-based, polyurethane-based, polyolefin-based, polystyrene-based, polyacrylic-based, polydiene-based, silicone-modified polycarbonate-based, and fluorine-based copolymerization system as thermoplastic elastomers. .. Further, examples of the thermosetting property include polyurethane-based, silicone-modified epoxy-based, and silicone-modified acrylic-based.
Examples of the rubber material include isoprene rubber, styrene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, butyl rubber, silicone rubber, chloroprene rubber, acrylic rubber, chlorosulfonated polyethylene, fluororubber, urethane rubber, and hydrin rubber. ..
In the present invention, a material that can obtain desired performance can be appropriately selected from the above-mentioned various elastomers and rubbers, and among them, ozone resistance, flexibility, adhesion to spherical fine particles, and flame retardancy are imparted. Acrylic rubber is most preferable from the viewpoint of environmental stability. Hereinafter, a case where the elastic layer 12 contains an acrylic rubber will be described as a preferred example of the present invention, but the present invention is not limited to the following examples.

The acrylic rubber used for the elastic layer 12 of the present invention can be the one currently on the market and is not particularly limited. However, among the various cross-linking systems (epoxide group, active chlorine group, carboxyl group) of acrylic rubber, the carboxyl group cross-linking system is excellent in rubber physical characteristics (particularly compression permanent strain) and processability, so the carboxyl group cross-linking system is selected. It is preferable to do so.

The cross-linking agent used for the carboxyl group cross-linking acrylic rubber is preferably an amine compound, and most preferably a polyvalent amine compound. Specific examples of such an amine compound include an aliphatic polyvalent amine cross-linking agent and an aromatic polyvalent amine cross-linking agent. Examples of the aliphatic polyvalent amine cross-linking agent include hexamethylenediamine, hexamethylenediamine carbamate, N, N'-dicinnamylidene-1,6-hexanediamine and the like. Examples of the aromatic polyvalent amine cross-linking agent include 4,4'-methylenedianiline, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and 4,4'-(m-phenylenedi). Isopropyridene) dianiline, 4,4'-(p-phenylenediisopropyridene) dianiline, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminobenzanilide, 4, Examples thereof include 4'-bis (4-aminophenoxy) biphenyl, m-xylylenediamine, p-xylylenediamine, 1,3,5-benzenetriamine, 1,3,5-benzenetriaminomethyl and the like.

The blending amount of the cross-linking agent is preferably 0.05 to 20 parts by mass, and more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the acrylic rubber. When the blending amount of the cross-linking agent is 0.05 part by mass or more, the cross-linking is sufficiently performed and the shape of the cross-linked product can be easily maintained. On the other hand, when the amount is 20 parts by mass or less, the crosslinked product does not become too hard, and the elasticity of the crosslinked rubber becomes good.

In the elastic layer 12 of the present invention, a cross-linking accelerator may be further blended and used in combination with the above-mentioned cross-linking agent. The cross-linking accelerator is also not limited, but is preferably a cross-linking accelerator that can be used in combination with the polyvalent amine cross-linking agent. Examples of such a cross-linking accelerator include a guanidine compound, an imidazole compound, a quaternary onium salt, a polyvalent tertiary amine compound, a tertiary phosphine compound, and an alkali metal salt of a weak acid. Examples of the guanidine compound include 1,3-diphenylguanidine and 1,3-dioltotrilguanidine. Examples of the imidazole compound include 2-methylimidazole and 2-phenylimidazole. Examples of the quaternary onium salt include tetra n-butylammonium bromide and octadecyltri-n-butylammonium bromide. Examples of the polyvalent tertiary amine compound include triethylenediamine, 1,8-diaza-bicyclo [5.4.0] undecene-7 (DBU) and the like. Examples of the tertiary phosphine compound include triphenylphosphine and tri-p-tolylphosphine. Examples of the alkali metal salt of the weak acid include a phosphate of sodium or potassium, an inorganic weak acid salt such as a carbonate, or an organic weak acid salt such as stearate and lauryl salt.

The amount of the cross-linking accelerator used is preferably 0.1 to 20 parts by mass, and more preferably 0.3 to 10 parts by mass per 100 parts by mass of acrylic rubber. When the blending amount of the cross-linking accelerator is 0.1 part by mass or more, the tensile strength of the cross-linked product is improved, and the change in elongation or the change in tensile strength after heat loading is also small. When the blending amount of the crosslinking accelerator is 20 parts by mass or less, the crosslinking rate at the time of crosslinking can be suppressed, the bloom of the crosslinking accelerator on the surface of the crosslinking product, and the increase in hardness of the crosslinking product can be suppressed.

In preparing the acrylic rubber composition for providing the elastic layer 12, an appropriate mixing method such as roll mixing, Banbury mixing, screw mixing, and solution mixing can be adopted. The blending order is not particularly limited, but after sufficiently mixing the components that are difficult to react or decompose with heat, a component that easily reacts with heat or a component that easily decomposes, for example, a cross-linking agent, is used at a temperature at which reaction or decomposition does not occur. It may be mixed in a short time.

Acrylic rubber can be crosslinked by heating. The heating temperature is preferably 130 to 220 ° C, more preferably 140 ° C to 200 ° C, and the crosslinking time is preferably 30 seconds to 5 hours. As the heating method, a method used for cross-linking rubber such as press heating, steam heating, oven heating, and hot air heating may be appropriately selected. Further, after cross-linking once, post-cross-linking may be performed in order to reliably cross-link to the inside of the cross-linked product. Post-crosslinking varies depending on the heating method, crosslinking temperature, shape and the like, but is preferably carried out for 1 to 48 hours. The heating method and heating temperature at the time of post-crosslinking may be appropriately selected.

On the other hand, the thickness of the elastic layer 12 is preferably 200 μm to 600 μm, more preferably 300 μm to 500 μm. When the thickness of the elastic layer 12 is 200 μm or more, the image quality is sufficient for paper types having surface irregularities, and when it is 600 μm or less, the weight of the intermediate transfer belt is reduced and the deflection and warpage are prevented. However, the running performance can be stabilized, and cracks due to bending at the roller curvature portion for stretching the belt can be prevented. As a method for measuring the thickness, the cross section can be measured with a scanning microscope (SEM).

Materials such as a resistance modifier, an antioxidant, a reinforcing agent, a filler, and a vulcanization accelerator for adjusting the electrical characteristics may be appropriately added to the elastic layer 12, if necessary.

The resistivity control required for the intermediate transfer belt requires the addition of a conductive agent because the resistivity of acrylic rubber alone is high. Although carbon or an ionic conductive agent can be added to control the resistivity, in the present invention, it is preferable to use an ionic conductive agent which is effective even when added in a small amount and does not affect the rubber hardness. Specifically, it is preferable to add 0.01 to 3 parts by mass of various perchlorates and ionic liquids with respect to 100 parts by mass of acrylic rubber. When the amount of the ionic conductive agent added is 0.01 parts by mass or more, the effect of lowering the resistivity can be obtained, and when it is 3 parts by mass or less, bloom or bleeding of the conductive agent on the belt surface can be prevented.
The resistance value of the elastic layer 12 is preferably 1 × 10 ⁸ to 1 × 10 ¹³ Ω / □ for the surface resistance and 1 × 10 ⁷ to 1 × 10 ¹² Ω · cm for the volume resistance.

<Spherical fine particles>
Next, the spherical fine particles 13 contained in the elastic layer 12 will be described. The shape of the spherical fine particles 13 is preferably spherical particles from the viewpoint of toner transfer efficiency.
The spherical shape is defined as follows.
3A to 3C are diagrams schematically showing the shape of the spherical fine particles used in the present invention.
In FIGS. 3B to 3C, when the spherical fine particles are defined by the major axis r1, the minor axis r2, and the thickness r3 (where r1 ≧ r2 ≧ r3), the ratio of the major axis to the minor axis (r2 /). Spherical fine particles in which r1) is in the range of 0.9 to 1.0 and the ratio (r3 / r2) of the thickness to the minor axis is in the range of 0.9 to 1.0 are defined as spherical particles. ..
When the ratio of the major axis to the minor axis and the ratio of the thickness to the minor axis (r3 / r2) are 0.9 or more, it becomes easy to arrange the spherical fine particles on the surface of the elastic layer. Toner transfer efficiency is improved.
For the major axis r1, the minor axis r2, and the thickness r3, for example, spherical fine particles are uniformly dispersed and adhered on a smooth measurement surface, and 100 spherical fine particles are subjected to a color laser microscope "VK-8500" (manufactured by Keyence). The major axis r1 (μm), minor axis r2 (μm), and thickness r3 (μm) of 100 spherical fine particles are measured by magnifying to an arbitrary magnification (for example, 1,000 times), and their arithmetic averages are measured. It can be calculated from the value.

The material of the spherical fine particles 13 is not particularly limited, and examples thereof include spherical fine particles containing a resin such as a melamine resin, an acrylic resin, a polyamide resin, a polyester resin, a silicone resin, and a fluororesin as a main component. Further, the surface of the particles made of these resin materials may be surface-treated with a different material.
Further, the spherical fine particles 13 can also be formed by using a rubber material. As the spherical fine particles in the present invention, those having a structure in which the surface of the spherical fine particles made of a rubber material is coated with a hard resin can also be applied. It may also be hollow or porous.

Among these resins, the melamine resin is most preferable as it has slipperiness and has a high function of being able to impart adhesiveness to rubber, releasability to toner, and abrasion resistance. The spherical fine particles 13 are preferably particles produced into a spherical shape by a polymerization method or the like using these resins, and in the present invention, those closer to a true sphere are preferable. Further, the particle size of the spherical fine particles 13 has a volume average particle size of 1.0 μm to 5.0 μm, and is preferably monodisperse particles. The monodisperse particles referred to here do not mean particles having a single particle size, but refer to particles having an extremely sharp particle size distribution. Specifically, it may have a distribution width of ± (average particle size × 0.5) μm or less. When the volume average particle size of the spherical fine particles 13 is 1.0 μm or more, the transfer performance can be improved, and when the volume average particle size is 5.0 μm or less, the surface roughness becomes small and the gaps between the particles become small. Performance and cleaning performance are improved. Furthermore, since many of the spherical fine particles 13 have high insulating properties, the charging potential is less likely to remain when the volume average particle size is 5.0 μm or less, and image distortion during continuous image output can be suppressed. The timing of applying the spherical fine particles 13 to the surface of the elastic layer 12 is not particularly limited, and can be applied either before or after vulcanization of the rubber.

The spherical fine particles 13 are not particularly limited, and those synthesized as appropriate may be used, or commercially available products may be used. The commercially available products include silicone particles (Momentive Performance Materials, trade name "Tospearl 120", trade name "Tospearl 145", trade name "Tospearl 2000B"), acrylic particles (Sekisui Plastics Industry, product name " Techpolymer MBX-SS "), melamine particles (Nippon Shokubai Co., Ltd., trade name" Epostal S12 ") and the like.

The ratio of the spherical fine particles 13 in the elastic layer 12 is preferably 0.1 to 1 part by mass, more preferably 0.2 to 0.5 part by mass with respect to 100 parts by mass of the acrylic rubber of the elastic layer 12, for example.

<Flame retardant>
The elastic layer 12 in the present invention uses a combination of a phosphorus compound, a metal hydrate, and a clay mineral as a flame retardant. By combining the three types, a synergistic effect as a flame retardant can be exhibited, flame retardancy can be exhibited with a smaller amount, and resistance fluctuation can be suppressed even if the temperature and humidity change. As a specific resistance fluctuation, it is preferable that the difference between high temperature and high humidity and normal temperature and humidity is within one digit.

Examples of clay minerals include vermiculite, kaolin, mica, layered silicate and the like. Among these, layered silicate is preferable from the viewpoint of dispersibility in rubber. The layered silicate means a layered silicate mineral having exchangeable metal cations such as sodium ion and magnesium ion between layers. The silicate mineral may be a natural product or a synthetic product. Examples of the layered silicate include smectites such as montmorillonite, hectorite, saponite, stepnsite, byderite, and nontronite. Among them, montmorillonite is highly effective as a flame retardant and is suitable. These layered silicates may be used alone or in combination of two or more. As a commercially available product, such a material includes Cloisite manufactured by Big Chemie.
The average particle size of the clay mineral is preferably 1 μm to 30 μm, more preferably 5 μm to 20 μm.

Examples of the metal hydrate include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, zirconium hydroxide, dolomite, hydrotalcite, zinc hydroxystinate and the like. Of these, aluminum hydroxide is particularly preferable because it has excellent dispersibility in rubber and is advantageous in terms of flame retardancy and resistance to environmental fluctuations. As a commercial product of such a material, Showa Denko Corporation's Heidi Light can be mentioned.
The average particle size of the metal hydrate is preferably 0.1 μm to 10 μm, more preferably 1 μm to 3 μm.

Specific examples of the phosphorus compound include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, diphenyl octyl phosphate, triallyl phosphate, tricresyl phosphate and cresyl diphenyl. Phosphate, 2-ethylhexyldiphenyl phosphate, triallyl phosphate, tri (hydroxyphenyl) phosphate, diethylbis (hydroxyethyl) aminomethylphosphonate, tris (3-hydroxypropyl) phosphine oxide, dibutylhydrooxymethylphosphonate, di (butoxy) Phosphineyl propylamide, dimethylmethylphosphonate, guanidine phosphate, trisdichloropropyl phosphate, tris β-chloropropyl phosphate, polybromostyrene, ammonium polyphosphate, polyphosphate amide, polyphosphate melamine, red phosphorus, etc. Red phosphorus is most preferable because it has high flame retardancy. As a commercially available product, Nova Excel of Rinkagaku Kogyo can be mentioned as such a material.
The average particle size of the phosphorus compound is preferably 1 μm to 50 μm, more preferably 5 μm to 20 μm.

The amount of the flame-retardant agent to be blended is 1 to 20 parts by mass, preferably 5 to 15 parts by mass, and 1 to 150 parts by mass, preferably 5 to 20 parts by mass of the metal hydrate with respect to 100 parts by mass of acrylic rubber. By mass, the amount of clay mineral is 1 to 10 parts by mass, preferably 3 to 7 parts by mass. By adjusting the blending amount of the flame retardant within the above range, high flame retardancy can be obtained, and the image density is stable even if the temperature and humidity change.

<Surface condition of intermediate transfer belt>
Next, the surface state of the intermediate transfer belt in the present invention will be described.
As mentioned above, FIG. 2 is a plan view of the intermediate transfer belt of FIG. As shown in FIG. 2, in the present invention, it is preferable that the spherical fine particles 13 having a uniform particle size are arranged independently and in an orderly manner, and the overlapping of the spherical fine particles 13 is hardly observed. It is preferable that the particle size of each spherical fine particle 13 constituting this surface is also uniform, and specifically, it is preferable that the distribution width is ± (average particle size × 0.5) μm or less.
As shown in FIG. 2, if a method capable of limiting the overlap between the spherical fine particles 13 can be used, the particle size of the spherical fine particles 13 does not have to satisfy the distribution width.
It is preferable that the spherical fine particles 13 occupy 60% or more of the area of the surface of the elastic layer 12. By satisfying such an occupancy rate, the exposed portion area of the acrylic rubber of the elastic layer 12 can be reduced, the contact opportunity between the toner and the acrylic rubber can be reduced, and good transferability can be obtained. The occupancy rate is more preferably 66% or more.

In the form shown in FIGS. 1 and 2, the spherical fine particles 13 are partially embedded in the elastic layer 12, but the burial rate is preferably more than 50% and less than 100%. It is more preferably 51% to 90%. When the burial rate exceeds 50%, the detachment of the spherical fine particles 13 is suppressed even in a long-term use in an image forming apparatus, and the durability is improved. On the other hand, when the burial rate is less than 100%, the transfer performance due to the presence of the spherical fine particles 13 is improved.
The burial rate is a rate indicating how much of the particle size of the spherical fine particles 13 is buried in the thickness direction of the elastic layer 12. Note that the burial rate here exceeds 50% and is less than 100% does not mean that the burial rate of all spherical fine particles 13 exceeds 50% and is less than 100%, but is viewed from a certain viewpoint. The average burial rate at that time should be more than 50% and not less than 100%.
The burial rate is determined by observing any part of the surface of the elastic layer 12 with a cross-sectional SEM (5,000 times) using a scanning electron microscope (SEM, manufactured by KEYENCE Co., Ltd., device name: VE-7800). It can be measured by determining what proportion of the particle size of 10 spherical fine particles is buried in the thickness direction of 12, and calculating the average value thereof.
For example, when the burial rate is 50%, spherical fine particles completely buried in the elastic layer 12 are hardly observed in the cross-sectional observation with an electron microscope. In the present invention, the amount of spherical fine particles completely embedded in the elastic layer 12 is preferably 5% by number or less with respect to the entire spherical fine particles.

Next, an example of the method for manufacturing the intermediate transfer belt of the present invention will be described.
First, a method for producing the base layer 11 will be described.
The base layer 11 can be produced, for example, by using a coating liquid containing the polyimide resin precursor or the polyamide-imide resin precursor as a resin component and a filler such as an electric resistance adjusting material.
While slowly rotating a cylindrical mold, for example, a cylindrical metal mold, the coating liquid is applied and spread evenly over the entire outer surface of the cylinder by a liquid supply device such as a nozzle or a dispenser. (Forms a coating film). After that, the rotation speed is increased to a predetermined speed, and when the predetermined speed is reached, the rotation speed is maintained at a constant speed, and the rotation is continued for a desired time. Then, the solvent in the coating film is evaporated at a temperature of about 80 to 150 ° C. while gradually raising the temperature while rotating. In this process, it is preferable to efficiently circulate and remove atmospheric vapor (volatile solvent, etc.). When a self-supporting film is formed, the entire mold is transferred to a heating furnace (baking furnace) capable of high-temperature treatment, the temperature is gradually raised, and finally high-temperature heat treatment (baking) of about 250 ° C to 450 ° C is performed. ), And the polyimide resin precursor or the polyamide-imide resin precursor is sufficiently imidized or polyamide-imidized to form the base layer 11. After sufficiently cooling, the elastic layer 12 is continuously laminated.

The elastic layer 12 is formed by coating on the base layer 11 using a rubber paint (acrylic rubber composition) in which acrylic rubber, a cross-linking agent, a cross-linking accelerator and the like are dissolved in an organic solvent, and then the solvent is dried and vulcanized. It can be manufactured by. As the coating molding method, existing coating methods such as spiral coating, die coating, and roll coating can be applied as in the base layer 11, but the thickness of the elastic layer 12 is increased in order to improve the uneven transfer property. As a coating method for forming a thick film, die coating and spiral coating are excellent. Here, the spiral coating will be described. First, while rotating the base layer 11 in the circumferential direction and continuously supplying the rubber paint with a round or wide nozzle, the nozzle is moved in the axial direction of the base layer 11 to spiral the rubber paint on the base layer 11. Paint on. The rubber paint spirally applied on the base layer 11 is dried while being leveled by maintaining a predetermined rotation speed and drying temperature. After that, it is further vulcanized (crosslinked) at a predetermined vulcanization temperature to be formed.

<Belt surface condition manufacturing method>
The vulcanized elastic layer 12 is then sufficiently cooled, and subsequently, the spherical fine particles 13 are applied onto the elastic layer 12 to fix the spherical fine particles 13 on the elastic layer 12, and a desired seamless belt (intermediate transfer belt) is used. ). As a method of applying the spherical fine particles 13, as shown in FIG. 4, a powder supply device 45 and a pressing member 43 are installed, and a belt 42 coated with a base layer 11 and an elastic layer 12 is attached to a mold drum 41. While rotating the mold drum 41, the cast coating liquid containing the spherical fine particles 13 is uniformly sprinkled on the surface of the elastic layer 12 from the powder supply device 45, and the spherical fine particles 13 sprinkled on the surface are pressed by the pressing member 43. Press at a constant pressure. With this pressing member 43, the surplus spherical fine particles 13 are removed while embedding the spherical fine particles 13 in the elastic layer 12. In the present invention, in particular, by using the monodisperse spherical fine particles 13, in a simple step of only the smoothing step with such a pressing member, the elastic layer 12 is formed in the thickness direction (preferably also in the plane direction). Spherical fine particles 13 can be independently embedded in a single state, whereby an uneven shape can be formed on the surface of the elastic layer 12. The burial rate can be adjusted by the length of the pressing time of the pressing member.
The burial rate can be adjusted by other methods. For example, the burial rate can be adjusted by adjusting the pressing force of the pressing member 43. For example, although it depends on the viscosity, solid content, amount of solvent used, particle material, etc. of the casting coating liquid, as a guide, the pressing force is 1 mN / cm at a viscosity of the casting coating liquid of 100 to 100,000 mPa · s. By setting the range to about 1000 mN / cm, it is possible to achieve a burial rate of more than 50% and less than 100% relatively easily.

The spherical fine particles 13 are uniformly arranged on the surface of the elastic layer 12, and then heated at a predetermined temperature for a predetermined time while rotating to form an elastic layer 12 in which the spherical fine particles 13 are embedded. After sufficient cooling, the base layer is removed from the mold to obtain a desired seamless belt (intermediate transfer belt).

The resistance of the intermediate transfer belt thus produced is adjusted by varying the amount of carbon black and the ionic conductive agent. At this time, note that the resistance is likely to change depending on the size of the spherical fine particles 13 and the occupied area ratio. The resistance can be measured by using a commercially available measuring instrument, for example, by using a high rester manufactured by Dia Instruments.

<Image forming device>
The image forming apparatus of the present invention is developed by an image carrier on which a latent image is formed and can carry a toner image, a developing means for developing the latent image formed on the image carrier with toner, and the developing means. It has an intermediate transfer body on which the transferred toner image is primarily transferred, and a transfer means for secondary transfer of the toner image carried on the intermediate transfer body to a recording medium, and the intermediate transfer body is an intermediate of the present invention. It is characterized by being a transfer belt. Further, it also has other means appropriately selected as necessary, such as static elimination means, cleaning means, recycling means, control means and the like.
In this case, it is preferable that the image forming apparatus is a full-color image forming apparatus in which a plurality of latent image carriers having developing means for each color are arranged in series.

The electrophotographic apparatus (hereinafter, referred to as “image forming apparatus”) in the present invention will be described in detail below with reference to the drawings. The following is an example, and the present invention is not limited thereto.

FIG. 5 is a schematic diagram of a main part showing an example of the image forming apparatus of the present invention.
The intermediate transfer unit 500 including the belt member shown in FIG. 5 is composed of an intermediate transfer belt 501 or the like, which is an intermediate transfer body stretched on a plurality of rollers. Around the intermediate transfer belt 501, a secondary transfer bias roller 605 which is a secondary transfer charge applying means of the secondary transfer unit 600, a belt cleaning blade 504 which is an intermediate transfer body cleaning means, and a lubricant of a lubricant applying means. The lubricant coating brush 505 and the like, which are coating members, are arranged so as to face each other.

Further, a position detection mark (not shown) is provided on the outer peripheral surface or the inner peripheral surface of the intermediate transfer belt 501. However, on the outer peripheral surface side of the intermediate transfer belt 501, it is necessary to devise a position detection mark so as to avoid the passing area of the belt cleaning blade 504, which may cause difficulty in arrangement. In that case, A position detection mark may be provided on the inner peripheral surface side of the intermediate transfer belt 501. The optical sensor 514 as a mark detection sensor is provided at a position between the primary transfer bias roller 507 and the belt drive roller 508 over which the intermediate transfer belt 501 is bridged.

The intermediate transfer belt 501 includes a primary transfer bias roller 507, a belt drive roller 508, a belt tension roller 509, a secondary transfer facing roller 510, a cleaning facing roller 511, and a feedback current detecting roller 512, which are primary transfer charge applying means. It is stretched over. Each roller is made of a conductive material, and each roller other than the primary transfer bias roller 507 is grounded. A transfer bias controlled to a predetermined magnitude of current or voltage is applied to the primary transfer bias roller 507 by a constant current or constant voltage controlled primary transfer power supply 801 according to the number of overlays of toner images. ing.

The intermediate transfer belt 501 is driven in the arrow direction by a belt drive roller 508 that is rotationally driven in the arrow direction by a drive motor (not shown).
The intermediate transfer belt 501, which is a belt member, is usually a semiconductor or an insulator and has a single-layer or multi-layer structure. However, in the present invention, a seamless belt is preferably used, which improves durability and improves durability. , Excellent image formation can be realized. Further, the intermediate transfer belt is set to be larger than the maximum paper-passable size in order to superimpose the toner image formed on the photoconductor drum 200.

The secondary transfer bias roller 605, which is a secondary transfer means, has a contact / detachment mechanism as a contact / detachment means described later with respect to the belt outer peripheral surface of the intermediate transfer belt 501 of the portion stretched on the secondary transfer opposed roller 510. , It is configured to be connectable and detachable. The secondary transfer bias roller 605 is arranged so as to sandwich the transfer paper P, which is a recording medium, between the intermediate transfer belt 501 and the portion stretched on the secondary transfer facing roller 510, and has a constant current. A transfer bias of a predetermined current is applied by the controlled secondary transfer power supply 802.

The resist roller 610 feeds the transfer paper P, which is a transfer material, between the secondary transfer bias roller 605 and the intermediate transfer belt 501 stretched on the secondary transfer opposed roller 510 at a predetermined timing. Further, a cleaning blade 608, which is a cleaning means, is in contact with the secondary transfer bias roller 605. The cleaning blade 608 removes and cleans the deposits adhering to the surface of the secondary transfer bias roller 605.

In the color copying machine having such a configuration, when the image formation cycle is started, the photoconductor drum 200 is rotated counterclockwise indicated by an arrow by a drive motor (not shown), and Bk (Bk) (on the photoconductor drum 200) is placed on the photoconductor drum 200. Black) toner image formation, C (cyan) toner image formation, M (magenta) toner image formation, and Y (yellow) toner image formation are performed. The intermediate transfer belt 501 is rotated clockwise by the belt drive roller 508 as indicated by the arrow. Along with the rotation of the intermediate transfer belt 501, the primary transfer of the Bk toner image, the C toner image, the M toner image, and the Y toner image is performed by the transfer bias due to the voltage applied to the primary transfer bias roller 507. Finally, each toner image is superposed on the intermediate transfer belt 501 in the order of Bk, C, M, and Y.

For example, the Bk toner image formation is performed as follows.
In FIG. 5, the charging charger 203 uniformly charges the surface of the photoconductor drum 200 with a negative charge to a predetermined potential by corona discharge. The timing is determined based on the belt mark detection signal, and raster exposure with a laser beam is performed based on the Bk color image signal by a writing optical unit (not shown). When this raster image is exposed, the exposed portion of the surface of the photoconductor drum 200 that is initially uniformly charged loses the charge proportional to the amount of exposure light, and a Bk electrostatic latent image is formed. When the negatively charged Bk toner on the developing roller of the Bk developer 231K comes into contact with this Bk electrostatic latent image, the toner does not adhere to the portion of the photoconductor drum 200 where the charge remains, and the charge is charged. Toner is adsorbed on the absent portion, that is, the exposed portion, and a Bk toner image similar to the electrostatic latent image is formed.

The Bk toner image thus formed on the photoconductor drum 200 is primarily transferred to the outer peripheral surface of the intermediate transfer belt 501 which is driven and rotated at a constant speed in contact with the photoconductor drum 200. Some untransferred residual toner remaining on the surface of the photoconductor drum 200 after the primary transfer is cleaned by the photoconductor cleaning device 201 in preparation for reuse of the photoconductor drum 200. On the photoconductor drum 200 side, the process proceeds to the C image forming step after the Bk image forming step, the reading of the C image data by the color scanner starts at a predetermined timing, and the laser beam writing by the C image data causes the photoconductor drum. A C electrostatic latent image is formed on the surface of 200.

Then, the revolver developing unit 230 is rotated after the rear end portion of the Bk electrostatic latent image has passed and before the tip end portion of the C electrostatic latent image has reached, and the C developer 231C develops. It is set at the position and the C electrostatic latent image is developed with C toner. After that, the development of the C electrostatic latent image region is continued, but when the rear end of the C electrostatic latent image passes, the revolver developing unit is rotated as in the case of the previous Bk developing machine 231K, and then the next step is performed. Move the M developer 231M of the above to the development position. This is also completed before the tip of the next Y electrostatic latent image reaches the developing position. As for the image forming steps of M and Y, since the operations of reading color image data, forming an electrostatic latent image, and developing are the same as those of the above-mentioned Bk and C steps, the description thereof will be omitted.

The toner images of Bk, C, M, and Y sequentially formed on the photoconductor drum 200 in this way are sequentially aligned on the same surface on the intermediate transfer belt 501 and primary transfer is performed. As a result, a toner image in which a maximum of four colors are superimposed is formed on the intermediate transfer belt 501. On the other hand, at the time when the image forming operation is started, the transfer paper P is fed from a paper feeding unit such as a transfer paper cassette or a manual feed tray, and stands by at the nip of the resist roller 610.
Then, when the tip of the toner image on the intermediate transfer belt 501 touches the secondary transfer portion in which the nip is formed by the intermediate transfer belt 501 stretched on the secondary transfer opposed roller 510 and the secondary transfer bias roller 605. The resist roller 610 is driven so that the tip of the transfer paper P coincides with the tip of the toner image, and the transfer paper P is conveyed along the transfer paper guide plate 601. Registration alignment is performed.

In this way, when the transfer paper P passes through the secondary transfer unit, the transfer bias due to the voltage applied to the secondary transfer bias roller 605 by the secondary transfer power supply 802 causes the four-color layered toner image on the intermediate transfer belt 501. Is collectively transferred (secondary transfer) on the transfer paper P. The transfer paper P is conveyed along the transfer paper guide plate 601 and is statically eliminated by passing through a portion facing the transfer paper static elimination charger 606 composed of a static elimination needle arranged on the downstream side of the secondary transfer portion. , Is sent toward the fixing device 270 by the belt transport device 210, which is a belt component. Then, after the toner image is melt-fixed at the nip portion of the fixing rollers 271 and 272 of the fixing device 270, the transfer paper P is sent out of the main body of the device by a discharge roller (not shown) and stacked face up on a copy tray (not shown). Will be done. If necessary, the fixing device 270 may be configured to include a belt component.

On the other hand, the surface of the photoconductor drum 200 after the belt transfer is cleaned by the photoconductor cleaning device 201, and the static electricity is uniformly removed by the static elimination lamp 202. Further, the residual toner remaining on the outer peripheral surface of the belt of the intermediate transfer belt 501 after the toner image is secondarily transferred to the transfer paper P is cleaned by the belt cleaning blade 504. The belt cleaning blade 504 is configured to be brought into contact with and detached from the belt outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing by a cleaning member detaching mechanism (not shown).

On the upstream side of the intermediate transfer belt 501 of the belt cleaning blade 504 in the moving direction, a toner seal member 502 that comes into contact with and separates from the outer peripheral surface of the belt of the intermediate transfer belt 501 is provided. The toner seal member 502 receives the dropped toner dropped from the belt cleaning blade 504 during cleaning of the residual toner, and prevents the dropped toner from scattering on the transfer path of the transfer paper P. The toner seal member 502 is brought into contact with and detached from the belt outer peripheral surface of the intermediate transfer belt 501 together with the belt cleaning blade 504 by the cleaning member detaching mechanism.

The lubricant 506 scraped off by the lubricant application brush 505 is applied to the outer peripheral surface of the intermediate transfer belt 501 from which the residual toner has been removed in this manner. The lubricant 506 is made of a solid body such as zinc stearate and is arranged so as to come into contact with the lubricant application brush 505. Further, the residual charge remaining on the outer peripheral surface of the belt of the intermediate transfer belt 501 is removed by the static elimination bias applied by the belt static elimination brush (not shown) in contact with the outer peripheral surface of the belt of the intermediate transfer belt 501. Here, the lubricant application brush 505 and the belt static elimination brush are brought into contact with and detached from the belt outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing by their respective attachment / detachment mechanisms (not shown). ..

Here, at the time of repeat copying, the operation of the color scanner and the image formation on the photoconductor drum 200 are performed on the second first color at a predetermined timing following the image forming step of the first fourth color (Y). Proceed to the image forming step of (Bk). Further, the intermediate transfer belt 501 is a second Bk toner in the area cleaned by the belt cleaning blade 504 on the outer peripheral surface of the belt, following the batch transfer step of the first four-color laminated toner image to the transfer paper. Allow the image to be primarily transferred. After that, the operation is the same as that of the first sheet. The above is the copy mode for obtaining a 4-color full-color copy, but in the case of the 3-color copy mode and the 2-color copy mode, the same operation as described above is performed for the specified color and the number of times. Further, in the case of the single color copy mode, only the developing machine of the predetermined color of the revolver developing unit 230 is put into the developing operation state, and the belt cleaning blade 504 is kept in contact with the intermediate transfer belt 501 until the predetermined number of sheets is completed. Perform the copy operation in the state.

In the above embodiment, the copying machine provided with only one photoconductor drum 1 has been described, but the present invention has, for example, a plurality of photoconductor drums as shown in the schematic diagram of the main part of FIG. It can also be applied to an image forming apparatus arranged side by side along one intermediate transfer belt made of a seamless belt.
FIG. 6 is a configuration of a 4-drum digital color printer equipped with four photoconductor drums 21BK, 21Y, 21M, 21C for forming toner images of four different colors (black, yellow, magenta, cyan). An example is shown.

In FIG. 6, the printer main body 101 is composed of an image writing unit 112, an image forming unit 113, and a paper feeding unit 14 for forming a color image by an electrophotographic method. Based on the image signal, the image processing unit processes the image to convert it into black (BK), magenta (M), yellow (Y), and cyan (C) color signals for image formation, and transmits the image to the image writing unit 112. do. The image writing unit 112 is, for example, a laser scanning optical system including a laser light source, a deflector such as a rotating multifaceted mirror, a scanning imaging optical system, and a mirror group, and has four corresponding to each of the above color signals. The image carrier (photoreceptor) 21BK, 21M, 21Y, 21C, which has a writing optical path and is provided for each color of the image forming unit 113, writes an image according to each color signal.

The image forming unit 113 includes photoconductors 21BK, 21M, 21Y, and 21C, which are image carriers for black (BK), magenta (M), yellow (Y), and cyan (C). As each photoconductor for each color, an OPC photoconductor is usually used. Around each of the photoconductors 21BK, 21M, 21Y, and 21C, there is a charging device, an exposed portion of laser light from the writing unit 112, and developing devices 20BK, 20M, 20Y for each color of black, magenta, yellow, and cyan. 20C, primary transfer bias rollers 23BK, 23M, 23Y, 23C as primary transfer means, a cleaning device (not shown), a photoconductor static elimination device (not shown), and the like are arranged. A two-component magnetic brush developing method is used for the developing devices 20BK, 20M, 20Y, and 20C. The intermediate transfer belt 22 which is a belt component is interposed between the photoconductors 21BK, 21M, 21Y, 21C and the primary transfer bias rollers 23BK, 23M, 23Y, 23C, respectively, and is formed on each photoconductor. The toner images of each color are sequentially superimposed and transferred.

On the other hand, the transfer paper P is fed from the paper feed unit 14, and then supported on the transfer transfer belt 50, which is a belt constituent unit, via the resist roller 16. Then, at the point where the intermediate transfer belt 22 and the transfer transfer belt 50 come into contact with each other, the toner image transferred on the intermediate transfer belt 22 is secondarily transferred (batch transfer) by the secondary transfer bias roller 60 as the secondary transfer means. ). As a result, a color image is formed on the transfer paper P. The transfer paper P on which the color image is formed is conveyed to the fixing device 15 by the transfer transfer belt 50, and after the image transferred by the fixing device 15 is fixed, it is discharged to the outside of the printer main body.

The residual toner that is not transferred during the secondary transfer and remains on the intermediate transfer belt 22 is removed from the intermediate transfer belt 22 by the belt cleaning member 25. A lubricant application device 27 is arranged on the downstream side of the belt cleaning member 25. The lubricant applying device 27 includes a solid lubricant and a conductive brush that rubs against the intermediate transfer belt 22 to apply the solid lubricant. The conductive brush is in constant contact with the intermediate transfer belt 22 to apply a solid lubricant to the intermediate transfer belt 22. The solid lubricant has the effect of improving the cleaning property of the intermediate transfer belt 22, preventing the occurrence of filming, and improving the durability.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples, and these Examples are appropriately modified without departing from the gist of the present invention. Is also within the scope of the present invention.

[Example 1, Example 2, Example 3, Example 4]
A coating liquid for a base layer was prepared according to the following, and a seamless belt base layer was manufactured using this coating liquid.

<Preparation of coating liquid for base layer>
First, carbon black (SpecialBlack4; Evonik Degussa), which was previously dispersed in N-methyl-2-pyrrolidone in a polyimide varnish (U-Wanis A; manufactured by Ube Industries, Ltd.) containing a polyimide resin precursor as a main component, was previously dispersed in N-methyl-2-pyrrolidone by a bead mill. The dispersion liquid was prepared so that the carbon black content was 16.7 [mass%] of the solid acid content of the polyamic acid, and the mixture was well stirred and mixed to prepare a coating liquid.

<Manufacturing of polyimide base layer belt>
A metal cylindrical support having an outer diameter of 340 [mm] and a length of 360 [mm] roughened by blasting was used as a mold and attached to a roll coat coating device. Subsequently, the coating liquid for the base layer is poured into the pan, the paint is pumped up at the rotation speed of the coating roller of 40 [mm / sec], and the gap between the regulation roller and the coating roller is set to 0.6 [mm] on the coating roller. The paint thickness was controlled.

After that, the rotation speed of the cylindrical support is controlled to 35 [mm / sec] to bring it closer to the coating roller, the gap with the coating roller is set to 0.4 [mm], and the paint on the coating roller is uniformly applied to the cylindrical support. After transfer coating on top, put it in a hot air circulation dryer while maintaining rotation, gradually raise the temperature to 110 [° C] and heat for 30 minutes, then raise the temperature further and heat at 200 [° C] for 30 minutes. , Stopped rotation. Then, this was introduced into a heating furnace (firing furnace) capable of high temperature treatment, the temperature was gradually raised to 320 [° C.], and the heat treatment (firing) was performed for 60 minutes. It was sufficiently cooled to obtain a polyimide base layer belt A.

<Preparation of elastic layer on polyimide base layer belt>
Various rubber compositions for forming an elastic layer were prepared by blending and kneading each component shown in Table 1 below at the ratio shown in the same table.

The components used in Table 1 are as follows.
Acrylic rubber: ZEON CORPORATION Nipole AR12
Stearic acid: Beads made by NOF Corporation Tsubaki Stearic acid Red phosphorus: Made by Rinkagaku Kogyo Co., Ltd. Nova Excel 140F
Melamine polyphosphate: ADEKA FP-2100JC
Aluminum hydroxide: Showa Denko Corporation Heidi Light H42M
Magnesium hydroxide: Kisma 5A manufactured by Kyowa Chemical Industry Co., Ltd.
Clay mineral: CLOISITE5 (montmorillonite) manufactured by Big Chemie
Crosslinking agent: Dupontow Elastomer Japan manufactured DIak. No1 (hexamethylenediamine carbamate)
Crosslinking accelerator: VULCOFAC ACT55 manufactured by Saffic alcan (70% 1,8-diazabicyclo (5,4,0) salt of undecene-7 and dibasic acid, 30% amorphous silica)
Conductive agent: QAP-01 (tetrabutylammonium perchlorate) manufactured by Carlit Japan Co., Ltd.

Next, the rubber composition thus obtained was dissolved in an organic solvent (MIBK: methyl isobutyl ketone) to prepare a rubber solution having a solid content of 35 [wt%]. The prepared rubber solution is moved to the axial method of the support while continuously ejecting the rubber solution from the nozzle onto the polyimide base layer belt while rotating the cylindrical support on which the previously prepared polyimide base layer belt is formed. It was painted in a spiral shape. The coating amount was set so that the final film thickness was 400 [μm]. After that, the cylindrical support coated with the rubber solution was put into a hot air circulation dryer while rotating as it was, and the temperature was raised to 90 [° C] at a heating rate of 4 [° C / min] and heated for 30 minutes. ..

Then, it is taken out from the dryer and cooled, and on the surface thereof, silicone spherical fine particles (Eposter S12 (volume average particle size 1.2 [μm] product); Nippon Catalyst, as spherical fine particles 13 are used. (Spherical particles) were evenly sprinkled on the surface, and the pressing member of the polyurethane rubber blade was pressed against the elastic layer 12 with a pressing pressure of 100 [mN / cm]. Then, it was put into the hot air circulation dryer again, heated to 170 [° C.] at a heating rate of 4 [° C./min], and heat-treated for 60 minutes. Belt B (Example 2), intermediate transfer belt C (Example 3), and intermediate transfer belt D (Example 4) were obtained.
In the intermediate transfer belts of Examples 1 to 4, the spherical fine particles occupied 66% of the surface area of the elastic layer. The burial rate of the spherical fine particles in the elastic layer was 55%.

[Example 5]
Examples 1 to 4 were repeated except that the elastic layer forming rubber composition shown in Examples 1 to 4 was changed to the elastic layer forming rubber composition shown in Table 2, and the intermediate transfer belt E (Example 5) was repeated. ) Was obtained.

The components used in Table 2 are as follows.
Hydrogenated Nitrile Rubber: Zeon Corporation Zet Pole 2020L
Stearic acid (Beaded stearic acid camellia manufactured by NOF CORPORATION)
Sulfur: Tsurumi Chemical Industry 200mesh Sulfur Zinc Oxide: Shodo Chemical Industry Zinc Oxide Type 2 Vulcanization Accelerator: Noxeller TS (Tetramethylthiuram Monosulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Akarin: Nova Excel 140F manufactured by Rin Kagaku Kogyo Co., Ltd.
Aluminum hydroxide: Showa Denko Corporation Heidi Light H42M
Conductive agent: QAP-01 (tetrabutylammonium perchlorate) manufactured by Carlit Japan Co., Ltd.

In the intermediate transfer belt of Example 5, the spherical fine particles occupied 72% of the surface area of the elastic layer. The burial rate of the spherical fine particles in the elastic layer was 60%.

<Comparative Examples 1 to 3>
Examples 1 to 4 were repeated except that the elastic layer forming rubber compositions shown in Examples 1 to 4 were changed to various elastic layer forming rubber compositions shown in Table 3, and the intermediate transfer belt F (Comparative Example) was repeated. 1), an intermediate transfer belt G (Comparative Example 2), and an intermediate transfer belt H (Comparative Example 3) were obtained. The various components used are the same as in Examples 1 to 4.

In the intermediate transfer belts of Comparative Examples 1 to 3, the spherical fine particles occupied 68% of the surface area of the elastic layer. The burial rate of the spherical fine particles in the elastic layer was 55%.

<Comparative example 4 >
Example 5 was repeated except that the elastic layer forming rubber composition shown in Example 5 was changed to the elastic layer forming rubber composition shown in Table 4, and an intermediate transfer belt I (Comparative Example 4) was obtained. .. The various components used are the same as in Example 5.

In the intermediate transfer belt of Comparative Example 4, the spherical fine particles occupied 63% of the surface area of the elastic layer. The burial rate of the spherical fine particles in the elastic layer was 60%.

The following evaluations were performed on the intermediate transfer belts A to I of each of the above Examples and Comparative Examples.

(Flame retardance)
It was performed according to the UL-94 V test.

(Resistance environment change)
Using a high rester from Mitsubishi Chemical Analytech, the volume resistivity when 500V was applied for 10 seconds was measured as the resistance value. The measurement environment was 23 ° C. 50% RH (MM environment) and 27 ° C. 80% RH (HH environment).

(Image density)
The intermediate transfer belts A to I of each of the above Examples and Comparative Examples are mounted on the image forming apparatus of FIG. Was output 10 sheets at a time, and the image densities were compared. Judgment was that ○ indicates no change, Δ indicates that the concentration is low in the HH environment but is at an actual usable level, and × indicates that the concentration is too low in the HH environment and cannot be used.

The results are shown in Table 5. The "digit" in the resistance environment fluctuation means a value obtained by subtracting the "usual logarithmic value of the resistivity of the HH environment" from the "usual logarithmic value of the resistivity of the MM environment".

From the results in Table 5, it can be seen that the intermediate transfer belt of the example has high flame retardancy and the image density is stable even when the temperature and humidity change.

(Code in FIGS. 1 and 2)
11 Base layer 12 Elastic layer 13 Spherical fine particles (reference numerals in FIGS. 3A, B, C)
r1 major axis r2 minor axis r3 thickness (reference numeral in FIG. 4)
41 Mold drum 42 Belt coated with base layer and elastic layer 43 Pressing member 45 Powder supply device (reference numeral in FIG. 5)
P Transfer paper L Laser light 70 Static elimination roller 80 Earth roller 200 Photoconductor drum 201 Photoreceptor cleaning device 202 Static elimination lamp 203 Charging charger 204 Potential sensor 205 Image density sensor 210 Belt carrier 230 Revolver developing unit 231Y Y developing machine 231K Bk developing machine 231CC developer 231MM M developer 270 Fixing device 271, 272 Fixing roller 500 Intermediate transfer unit 501 Intermediate transfer belt 502 Toner seal member 503 Charged charger 504 Belt cleaning blade 505 Lubricating brush 506 Lubricator 507 Primary transfer bias roller 508 Belt drive roller 509 Belt tension roller 510 Secondary transfer facing roller 511 Cleaning facing roller 512 Feed bag Current detection roller 513 Toner image 514 Optical sensor 600 Secondary transfer unit 601 Transfer paper guide plate 605 Secondary transfer bias roller 606 Transfer paper static elimination charger 608 Cleaning blade 610 Resist roller 801 Primary transfer power supply 802 Secondary transfer power supply (reference numeral in FIG. 6)
P Transfer paper 101 Printer body 112 Image writing unit 113 Image forming unit 14 Feeding unit 15 Fixing device 16 Resist roller 20BK, 20M, 20Y, 20C Developing device 21BK, 21M, 21Y, 21C Photoreceptor 22 Intermediate transfer belt 23BK, 23M , 23Y, 23C Primary transfer bias roller 25 Belt cleaning member 26 Drive roller 27 Lubricant application device 50 Transfer transfer belt 60 Secondary transfer bias roller

Japanese Unexamined Patent Publication No. 2012-198329

Claims (7)

An intermediate transfer belt on which a toner image obtained by developing a latent image formed on an image carrier with toner is transferred.
The intermediate transfer belt has a laminated structure including a base layer and an elastic layer containing spherical fine particles and having an uneven shape due to the spherical fine particles.
The elastic layer contains a phosphorus compound, a metal hydrate and a clay mineral, and contains acrylic rubber or hydrogenated nitrile rubber.
An intermediate transfer belt characterized by that. The intermediate transfer belt according to claim 1, wherein the clay mineral is a layered silicate. The intermediate transfer belt according to claim 1 or 2, wherein the metal hydrate is aluminum hydroxide. The intermediate transfer belt according to any one of claims 1 to 3, wherein the phosphorus-based compound is red phosphorus. A claim characterized in that a part or all of the spherical fine particles are independently embedded in a single state in the thickness direction of the elastic layer, thereby forming an uneven shape on the surface of the elastic layer. Item 4. The intermediate transfer belt according to any one of Items 1 to 4 . An image carrier on which a latent image is formed and can support a toner image,
A developing means for developing a latent image formed on the image carrier with toner, and
An intermediate transfer body to which the toner image developed by the developing means is primarily transferred, and
It has a transfer means for secondary transfer of the toner image supported on the intermediate transfer body to a recording medium.
An image forming apparatus according to any one of claims 1 to 5 , wherein the intermediate transfer body is the intermediate transfer belt. The image forming apparatus according to claim 6 , wherein the image forming apparatus is a full-color image forming apparatus, and a plurality of latent image carriers having development means for each color are arranged in series.

Images