JP4533038B2 - Transfer conveyor belt and image forming apparatus - Google Patents

Description

  The present invention relates to a transfer conveyance belt and an image forming apparatus used in an electrophotographic apparatus.

  In recent years, a plurality of image forming units are arranged around the transfer conveyance belt, and the image formed on the image carrier of each image forming unit is transferred to a transfer material such as paper adsorbed on the transfer conveyance belt, There has been proposed a tandem type image forming apparatus that forms a single image on a transfer material.

In such a tandem type full-color image forming apparatus, an important issue in forming a high-quality image is
(1) Each color component image of a full color image formed on an image carrier of each color of yellow, magenta, cyan, and black is formed on a transfer material without being misaligned (hereinafter simply referred to as “color shift”). thing,
(2) The image density of yellow, magenta, cyan and black is constant regardless of the use environment and the number of durable sheets, and the color reproducibility when outputting the same image is excellent.
It is.

  In order to solve such problems, the tandem type full-color image forming apparatus has an optical sensor for detecting color misregistration, toner density, etc. in order to adjust the color misregistration and color tone, and has the obtained information. In addition, the color misregistration and the color tone are adjusted by feeding back the image forming conditions in the image forming unit.

Examples of a method of adjusting the color shift, the sample toner images of each color formed by the image forming unit is transferred to the transfer conveyor belt, on the basis of the toner image of a certain color (e.g., yellow sample toner image image the position in the standards), the positional deviation amount of the sample toner image image of another color is detected by an optical sensor (registration detection sensor), position adjustment to suit the amount of positional deviation of the folding mirror has been detected in the scanner The color shift (position shift) of the toner image of each color is corrected by adjusting the position of the laser writing on the photosensitive drum or changing the image writing timing for each color.

As an example of the toner density adjustment method, a sample toner image (halftone image or solid image) for each color formed in each image forming unit is transferred to a transfer conveyance belt, and the sample toner image on the transfer conveyance belt is transferred. The image is read by an optical sensor (density detection sensor), and the density is adjusted by adjusting the development bias and exposure amount of each color. There are roughly two types of density detection sensors: the irregular reflection method and the regular reflection method. However, the toner concentration of each color can be detected regardless of the color of the transfer conveyance belt (strictly, the absorption wavelength of light emitted from the sensor). A reflection type density sensor is generally used. When this regular reflection type sensor is used, there is no restriction on the color of the surface of the transfer conveyance belt as described above, but it is affected by the surface property of the belt. Specifically, the reflectance (gloss) of the belt surface is A high one is preferred.

As described above, in order to suppress the color shift and the change in color tone, which are the conditions for a high-quality full-color image, the sample toner on the transfer conveyance seamless belt is used although the above-described control is performed on the image forming apparatus side. images since it is detected by the optical sensor over the reflection of the transfer conveyance sample toner image image is transferred seamless belt surface condition of the concrete to the transfer conveyor belt surface light (often infrared light) The influence of the rate (gross) on each control described above is very large. That is, a transfer / conveying belt having a high gloss on the surface of the transfer / conveying belt and small change due to durability is necessary for performing highly reliable color misregistration control and density control.

  Further, even if the image writing timing for each color is adjusted as described above, if the transfer material such as paper is not firmly adsorbed on the transfer conveyance belt, the transfer material itself passes through each image forming unit. Misalignment occurs, resulting in color misregistration in the resulting image. That is, the adsorptivity of the recording medium to the transfer / conveying belt surface is also a very important characteristic required for the transfer / conveying belt.

  For such required characteristics, for example, by reducing the surface energy of the belt (see Patent Document 1) or adding a fluorosurfactant (see Patent Document 2), the releasability of the belt surface is increased. Proposals have been made. Further, a proposal has been made that a stable recording medium adsorption effect can be obtained by adjusting the charging characteristics of the belt surface and the charging characteristics of the recording medium to have opposite polarities (see Patent Document 3).

  However, when these belt members are used as a transfer conveyance belt of an electrophotographic apparatus, paper powder (mainly calcium carbonate as a filler) adheres to the surface of the seamless belt due to durability, and good density control and color misregistration control cannot be performed. There was a case. In addition, color misregistration may occur due to insufficient adsorption of a transfer material such as paper to the transfer conveyance belt.

  In particular, an image forming apparatus that cleans the surface of a member by an electric field (see Patent Document 4) has advantages such as simplification of the apparatus configuration as compared with an apparatus having a blade cleaning mechanism. Since there is no mechanism for mechanically cleaning paper dust on the surface of the belt, paper dust is likely to adhere, and the transfer and transport belt is required to be less contaminated with paper dust.

  Further, in recent years, for the purpose of reducing the installation area of the image forming apparatus, the yellow, magenta, cyan, and black image forming units are not arranged in the horizontal direction, but are arranged in the vertical direction (or obliquely) as shown in FIG. The image forming apparatuses arranged in the above are also proposed. In this type of image forming apparatus, a transfer material adsorbing property higher than that of an image forming apparatus having a plurality of image forming units in the horizontal direction is required, and the transfer material adsorbing force is insufficient with a conventional transfer conveyance belt. There was a case.

That is, the conventional transfer / conveying belt cannot sufficiently satisfy the characteristics required for the transfer / conveying belt, such as contamination resistance to the paper dust on the surface of the transfer / conveying belt and the adsorbability of the transfer material. Also in the image forming apparatus, the above-described effects of high image quality control (color shift control, density control, etc.) are not sufficient, and the resulting image quality is not satisfactory.
Japanese Patent No. 3019781 JP-A-8-286521 JP 2000-344376 A JP-A-9-304998

  Accordingly, the present inventors propose a new transfer / conveying belt that is different from the conventional ones and solves the above-mentioned problems.

  An object of the present invention is to provide a transfer / conveying belt that achieves both stable adsorption of a recording medium and reduction of contamination due to paper dust adhesion.

  Another object of the present invention is to provide an image forming apparatus that is simple in structure and can be miniaturized with little change in image quality due to durability.

According to the onset bright, transfer conveyor belt der for conveying the recording medium which is electrostatically attracted to the image transfer position of the plurality of image forming portions,
The transfer conveyance belt contains at least a thermoplastic resin and a conductive filler;
When the relative dielectric constant of the transfer / conveying belt is εb and the hydrogen bond component of the surface energy of the transfer / conveying belt is γb [mN / m], the following relationship is satisfied :
The outermost surface of the transfer conveyor belt, to have at least a surfactant
A transfer / conveying belt is provided .
15 ≦ εb ≦ 50
0.02 ≦ γb ≦ 30
5 ≦ (εb) ^1/2 + (γb) ^1/2 ≦ 10

According to the onset bright, has the transfer conveyance belt, the image forming apparatus is provided with means for detecting the said transfer conveyor belt surface optically.

  As described above, according to the present invention, it is possible to provide a transfer / conveying belt and an image forming apparatus that achieve both stable adsorption of a recording medium and reduction of contamination due to paper dust adhesion.

  As a result of investigations to solve the above problems, the present inventors have found that a substance called “paper dust” that adheres to the surface of the transfer conveyance belt due to durability is not fine paper powder, and most of it is paper filler. I have determined that it is an inorganic substance such as calcium carbonate. Therefore, as a result of intensive studies on the characteristics that can satisfy the adsorption force of the transfer material such as paper while suppressing the adhesion of calcium carbonate to the transfer conveyance belt, the relative permittivity εb of the transfer conveyance belt and the surface of the transfer conveyance belt It has been found that the above problem can be solved when the hydrogen bond component γb [mN / m] of the surface energy is in a specific range and the sum of the square roots of both is in a specific range.

In other words, the following relationship is satisfied—providing a transfer / conveying belt that achieves both stable adsorption of a recording medium and reduction of contamination due to adhesion of paper dust (mainly adhering calcium carbonate as a filler). it can;
15 ≦ εb ≦ 50
0.02 ≦ γb ≦ 30
5 ≦ (εb) ^1/2 + (γb) ^1/2 ≦ 10

The relative permittivity εb of the transfer / conveyance belt is less than 15, or the hydrogen bond component γb [mN / m] of the surface energy of the transfer / conveyance belt is less than 0.02, or (εb) ^1/2 + (γb) ^{1 / In} the case of ² <5, contamination of the transfer conveyance belt surface due to adhesion of paper dust (mainly adhesion of calcium carbonate as a filler) becomes significant, and the gloss of the transfer conveyance belt surface decreases significantly as the transfer conveyance belt is used. It becomes. When a transfer / conveying belt with a significant decrease in gloss is used in an image forming apparatus, it can be used without any particular problems at the beginning of use of the image forming apparatus, but stable color shift control and density control cannot be performed as durability progresses. Only low-quality images with shifts or color changes can be output.

Further, the relative dielectric constant εb of the transfer / conveyance belt exceeds 50, the hydrogen bond component γb [mN / m] of the surface energy of the transfer / conveyance belt exceeds 30, or 10 <(εb) ^1/2 + ( In the case of γb) ^1/2 , the recording medium cannot be stably adsorbed onto the surface of the transfer / conveyance belt, and a so-called color misregistration in which the position of each color component image deviates from the initial output image occurs.

  A preferable range of the relative dielectric constant of the transfer / conveyance belt is 20 ≦ εb ≦ 40, and a preferable range of the hydrogen bond component γb of the surface energy on the transfer / conveyance belt surface is 0.1 ≦ γb ≦ 10.

  Further, the value obtained by dividing the maximum value of relative dielectric constant in each part of the transfer / conveyance belt by the minimum value (variation of relative dielectric constant) is preferably 2 or less, and more preferably 1.5 or less. If the relative dielectric constant of the transfer / conveyance belt is large, the degree of contamination due to endurance of paper passing partially changes, which makes it difficult to control the stable image formation.

  The dielectric constant of the transfer / conveying belt depends on the type of thermoplastic resin used and the melt viscosity (dispersion state of the conductive filler in the thermoplastic resin when the conductive filler is kneaded and dispersed in the thermoplastic resin, etc. Influences), the type of conductive filler, the addition amount and dispersion state, the kneading method, the kneading temperature, the additive and the like. In addition, the hydrogen bond component of the surface energy on the transfer / conveying belt surface includes the type of thermoplastic resin used, the method of forming the seamless belt, the type and amount of additives, the presence or absence of surface treatment, the surface treatment strength, and the addition of surfactants. Therefore, the relative dielectric constant and surface energy hydrogen bonding component of the transfer / conveyance belt can be controlled by optimizing them.

  The method for measuring the relative dielectric constant of the transfer / conveying belt and the method for measuring the hydrogen bond component of the surface energy will be described below.

<Measurement method of relative permittivity of transfer conveyance belt>
(1) As shown in FIG. 1, the transfer conveyance belt has a diameter from a total of 12 locations including 4 locations in the circumferential direction (in increments of 90 °) and 3 locations in the axial direction (positions equally divided into 4 in the belt axial direction). Cut out at 56 mm.
(2) Using a mild ion sputtering E1030 (manufactured by Hitachi, Ltd.) on the entire back surface of the transfer conveyance belt, sputtering is performed with a target-sample distance of 30 mm, a discharge current of 15 mA, and a discharge time of 120 seconds. Form.
(3) Using a mild ion sputter E1030 (manufactured by Hitachi, Ltd.) on the surface side of the transfer conveyance belt, sputtering is performed with a target-sample distance of 30 mm, a discharge current of 15 mA, and a discharge time of 120 seconds. A 51 mm guard electrode and a measurement electrode with a diameter of 50 mm are provided with platinum-palladium to prepare a measurement sample.
(4) The thickness d [μm] of the sample is measured to the order of 1 μm using a dial gauge.
(5) The obtained measurement sample is aged in an environment of 23 ° C./55% Rh for 8 hours or more.
(6) The measurement sample is set on an LCR meter (HP4284A + dielectric measurement electrode: HP16451B, manufactured by Yokogawa Hewlett-Packard Company).
(7) 1 Vrms (100 Hz) is applied, and the value of Cp is measured in the “Cp-Rp” mode.
(8) Based on the obtained Cp, the relative dielectric constant ε of the measurement sample is calculated by the following formula;
ε = Cp [nF] × d [μm] /17.39
Where d: thickness of the sample.
(9) The value obtained by dividing the relative dielectric constant of each part of the transfer / conveyance belt by the minimum one is defined as the variation in the relative dielectric constant of the transfer / conveyance belt, and the average value of the relative dielectric constant of each part of the transfer / conveyance belt is εb. And

<Method for Measuring Hydrogen Bond Component of Surface Energy on Transfer Conveying Belt Surface>
The surface tension is composed of the following three components, and the surface tension [mN / m] of water, ethylene glycol and diiodomethane is as follows:
(Surface tension: γ ^total ) = (dispersion force: γ ^a ) + (dipole force: γ ^b ) + (hydrogen bonding force: γ ^c )
Water: (surface tension γ _L ^total : 72.8) = (γ _L ^a : 29.1) + (γ _L ^b : 1.3) + (γ _L ^c : 42.4)
Ethylene glycol: (surface tension γ _L ^total : 47.7) = (γ _L ^a : 30.1) + (γ _L ^b : 0.0) + (γ _L ^c : 17.6)
Diiodomethane: (surface tension γ _L ^total : 50.8) = (γ _L ^a : 46.8) + (γ _L ^b : 4.0) + (γ _L ^c : 0.0)
Here, γ _L ^total , γ _L ^a , γ _L ^b , and γ _L ^c are the surface tension, dispersion force, dipole force, and hydrogen bonding force of the liquid, respectively.

These liquids are dropped on the surface of the measurement target substance, and the relationship between the measured contact angle θ and the surface of the measurement target substance is expressed by the following equation (: Extended Fowks equation);
2 (γ _L ^a × γ _S ^a ) ^1/2 +2 (γ _L ^b × γ _S ^b ) ^1/2 +2 (γ _L ^c × γ _S ^c ) ^1/2 = γ _L ^total (1 + cos θ)
Here, γ _S ^a , γ _S ^b , and γ _S ^c are a dispersion force, a dipole force, and a hydrogen bonding force of the measurement target substance, respectively.

In order to obtain the dispersion force, dipole force, and hydrogen bonding force of the measurement target substance, the contact angle of the measurement target substance is measured with three kinds of measurement liquids, and each of the above expanded Fowks formulas has the respective γ _L ^total and γ By fitting _L ^a , γ _L ^b , γ _L ^c and the contact angle θ, it can be obtained by solving three simultaneous equations.

  In the present invention, the contact angle between the three measurement liquids, water, ethylene glycol, and diiodomethane, and the surface of the transfer conveyance belt is measured, and the dispersion force, dipole force, and hydrogen bonding force on the transfer conveyance belt surface are obtained and measured. The hydrogen bond force is defined as the hydrogen bond component γb [mN / m] of the surface energy on the transfer conveyance belt surface. A method for measuring the contact angle will be described below.

<Measurement method of contact angle>
(1) Cut out the transfer conveyance belt to an appropriate size.

  (2) The cut sample is attached to an aluminum cylinder with a diameter of 50 mm.

  (3) Set the aluminum cylinder with the sample on the goniometer-type contact angle measuring instrument (manufactured by Kyowa Interface Science Co., Ltd.), and drop the liquid for measurement three times each after 10 seconds. Measure and use the average value as the contact angle of each measurement liquid.

  The thermoplastic resin that can be used in the transfer conveyance belt according to the present invention is not particularly limited as long as it satisfies the characteristics of the present invention as a transfer conveyance belt. For example, an olefin resin such as polyethylene or polypropylene, a polystyrene resin, or the like. Resins, acrylic resins, aromatic polyester resins such as polyethylene terephthalate, polycarbonate and polyarylate, alicyclic polyester resins such as cyclohexylenedimethylene terephthalate, sulfur-containing resins such as polysulfone, polyethersulfone and polyphenylene sulfide, polyvinylidene fluoride Fluorine-containing resins such as polyethylene-tetrafluoroethylene copolymer, polyurethane resin, silicone resin, ketone resin, polyvinylidene chloride, thermoplastic polyimide resin, polyamide resin, modified poly Although it is possible to use alkylene oxide resins, or the like, or various modified resins and copolymers it is not limited to the above materials. Moreover, these thermoplastic resins may be used independently and may be used in mixture of multiple types. Among these thermoplastic resins, polyamide resins, polyphenylene sulfide resins, and alicyclic polyester resins are particularly preferable because they easily control the properties required for the present invention and are excellent in mechanical properties. Further, polyamide 6 · 10 resin, polyamide 11 resin, and polyamide 12 resin, which have low water absorption, are also preferred as the polyamide resin. On the other hand, when a transfer conveyance belt is produced using an olefin resin, silicone resin, or fluorine resin as a binder resin, it is difficult to control the hydrogen bond component of the surface energy of the transfer conveyance belt within the range required by the present invention.

  In addition, as the conductive filler that can be used in the transfer conveyance belt according to the present invention, a known conductive filler can be used. However, since the electrical characteristics can be controlled in a wide range with a small amount of addition, the conductive carbon black can be used. Is preferred. A preferable addition amount of the conductive carbon black is 5 to 20% by mass.

  It is preferable to have at least a surfactant on the outermost surface of the transfer / conveying belt according to the present invention, and it is more preferable that the surfactant is one or a mixture of a hydrocarbon-based surfactant and a fluorine-based surfactant. . By having the surfactant on the outermost surface of the transfer conveyance belt, it becomes easy to control the hydrogen bonding component on the transfer conveyance belt surface. That is, the amount of the surfactant added to the transfer / conveying belt surface is not particularly limited as long as an amount satisfying the characteristics of the present invention is added. As the fluorine-based surfactant, various types of hydrocarbon surfactants in which part or all of the hydrogen atoms are substituted with fluorine atoms can be used. Specific examples include various fluorosurfactants shown below, but are not limited thereto.

・ Anionic fluorinated surfactants Perfluoroalkyl sulfonates (lithium salts, potassium salts, ammonium salts, etc.), perfluoroalkyl carboxylates (potassium salts, etc.), etc. ・ Nonionic fluorinated surfactants perfluoroalkylethylene oxide Additives, etc. ・ Cationic fluorosurfactant Perfluoroalkyl quaternary ammonium iodide, perfluoroalkyltrimethylammonium salt, etc.

  Here, as a means for containing a surfactant on the outermost surface of the transfer conveyance belt, it may be added to a thermoplastic resin or the like, kneaded and molded, or a surfactant may be applied to the surface of the transfer conveyance belt. . In the case of coating on the surface of the transfer / conveying belt, it is preferable that the coating is diluted and dissolved with an appropriate solvent because it can be uniformly coated. The coating method can be applied by a known method such as dip coating, spray coating, brush coating, a method in which a cloth impregnated with a surfactant is brought into contact with the belt, and is not particularly limited. .

  In addition to the conductive filler, the transfer / conveying belt contains 5 to 20% by mass of a non-conductive filler, which has the effect of stabilizing the relative permittivity of the transfer / conveying belt and is also durable. This is preferable because scratches are less likely to occur, a decrease in reflectance (gloss) on the surface of the transfer / conveyance belt can be suppressed, and good density and image position detectability can be obtained during image formation.

As the non-conductive filler that can be used in the present invention, any filler that does not have conductivity can be used without particular limitation. For example, zinc oxide, silicon oxide, titanium oxide, talc, mica, oxidation Although iron, magnesium oxide, tin oxide, etc. can be mentioned, it is not limited to these. In the present invention, the nonconductive filler refers to a filler having a powder resistance of 10 ⁵ Ω · cm or more. The powder resistance is measured by applying a voltage of 10 V to the flat portions at both ends of a measurement sample formed into a cylindrical shape (φ10 mm) by applying a pressure of 100 kg / cm ² to the powder to be measured, Calculate body resistance. In addition, as a method for measuring the powder resistance of the filler added to the belt, a component obtained by heating the transfer / conveying belt to 550 ° C. in air can be measured by the above-described powder resistance measurement method.

  Moreover, other components can be added as an additive in the range which does not inhibit the object of the present invention. Specific examples include organic pigments, inorganic pigments, pH adjusters, crosslinking agents, mold release agents, coupling agents, lubricants, antioxidants, hydrolysis inhibitors, and molding aids. Two or more of these can be combined.

In addition, it is preferable that the surface of the transfer / conveying belt is subjected to a surface modification treatment because the hydrogen bond component of the surface energy on the surface of the transfer / conveying belt, which is a characteristic necessary for the present invention, can be easily controlled. Specific examples of the surface modification treatment include ultraviolet irradiation treatment, electron beam irradiation treatment, plasma treatment, corona treatment, and ozone treatment, and corona treatment is particularly preferable because it can be treated with a relatively simple apparatus configuration with a short tact. preferable. The corona treatment conditions are preferably 30 to 600 KW · h / m ² . If it is less than 30 KW · h / m ² , the treatment effect is small, and if it exceeds 600 KW · h / m ² , the mechanical strength of the belt may decrease.

  It also has a transfer conveyance belt that conveys electrostatically attracted recording media to the image transfer positions of multiple image forming units, and optically detects the sample toner images formed on the transfer conveyance belt surface and the transfer conveyance belt. In the image forming apparatus having the above-described means, by using the transfer conveyance belt of the present invention as the transfer conveyance belt, stable image control can be performed regardless of durability.

That is, the sample toner images of each color formed by the image forming unit is transferred to the transfer conveyor belt, on the basis of the toner image of a certain color (e.g., based on the position of the sample toner image image of yellow), detecting the other position shift amount of the sample toner image image of a color with an optical sensor (registration detection sensor), the position of the laser writing to the photosensitive drum to adjust positions in accordance with the detected positional deviation amount to folding mirror in the scanner An image forming apparatus having a mechanism for correcting color misregistration (position misregistration) of each color toner image by adjusting or changing the image writing timing for each color, or each color formed by each image forming unit sample toner image (halftone image or a solid image) was transferred onto the transfer conveyance belt for each, a sample toner image image on the transfer conveyor belt Optimum for image formation by using the transfer conveyance belt of the present invention in an image forming apparatus having a mechanism that adjusts the density by adjusting the development bias and exposure amount of each color by reading with a scientific sensor (density detection sensor) Control can be performed without depending on durability, and high-quality images can be continuously obtained.

  Here, it is preferable from the viewpoint of miniaturization of the apparatus that the transfer conveyance belt does not have a member (such as an adsorption roller) for adsorbing the transfer medium. If the color characteristics are insufficient, a so-called color shift in which the position of each color component image is shifted in the output image occurs. However, it is possible to obtain an image having no color misregistration by using a transfer conveyance belt having excellent transfer material adsorbability such as paper of the present invention.

  In addition, the removal of the sample toner image for various controls formed on the surface of the transfer / conveyance belt, and the transfer of the image to be transferred onto the transfer material due to a paper feed failure (jam), etc. A mechanism for cleaning the surface of the transfer conveyance belt is necessary to remove the surface. However, as a cleaning mechanism for the surface of the transfer conveyance belt, the method of cleaning the surface of the transfer conveyance belt by an electric field is a reduction in size of the apparatus, This is preferable from the viewpoint of simplification. As an example of a method for cleaning the transfer conveyance belt by an electric field, the transfer conveyance belt is rotated while being brought into contact with the photosensitive drum, and a bias having the same polarity as the toner is applied to the transfer roller to thereby apply a bias to the photosensitive member on the transfer conveyance belt. There is a method of returning the toner to the photosensitive drum. Here, since some of the toners have reversed charging polarities, the polarity of the bias applied to the transfer roller is changed in each of a plurality of arranged image forming units (for example, first and third image formations). By applying a negative polarity bias to the transfer roller in the second and fourth image forming units), the toner on the transfer conveyance belt can be efficiently returned to the photosensitive drum.

  However, in the image forming apparatus that cleans the surface of the transfer / conveyance belt by the electric field as described above, the toner adhering to the transfer / conveyance belt can be removed, but the paper dust and the like cannot be sufficiently removed. When a transfer / conveying belt is used, contaminants such as paper dust adhering to the belt surface may not be removed, and the output image may be affected. By using a belt, stable image formation can be performed.

  The method for producing the transfer / conveying belt according to the present invention is not particularly limited, and a resistance control material obtained by kneading a thermoplastic resin and a conductive filler in advance is known, such as extrusion molding, inflation molding, blow molding, injection molding, and the like. Extrusion molding and inflation molding that can relatively easily obtain a thin molded product of about 50 to 200 μm that can be used as a transfer conveyance belt are preferable. Here, as a kneading method of the thermoplastic resin and the conductive filler, known kneading and dispersing methods can be used, but a twin screw extruder as shown in FIG. 4 is used because of high dispersibility and productivity. Kneading and dispersion are preferred. In particular, the kneading method in which the thermoplastic resin component is charged from the main hopper 41 and the conductive filler is charged from the sub hopper 42 when the thermoplastic resin component is softened to a certain extent provides stable dispersion of the conductive filler. Particularly preferred. By performing such kneading, the relative dielectric constant of the transfer / conveying belt can be stably obtained. When the dispersion of the conductive filler is not uniform, the relative dielectric constant of the transfer / conveyance belt partially changes, and the degree of contamination due to the endurance of paper passing partially changes. When such a transfer / conveyance belt is used, it is not preferable because stable control of image formation becomes difficult.

  Further, the tube-like film obtained by extrusion molding or inflation molding is subjected to secondary processing by a method described in JP-A No. 2001-38804, JP-A No. 2002-301864, or JP-A No. 2002-331579. May be performed. When performing such secondary processing, a substance imparting releasability may be applied to the surface of the tubular film or the member surface in contact with the surface of the tubular film as necessary. Depending on the combination of the material and the material of the transfer / conveying belt, the hydrogen bond component of the surface energy on the surface of the obtained transfer / conveying belt may be outside the scope of the present invention. In such a case, the effects of the present invention cannot be obtained. .

  An outline of the operation of the image forming apparatus of the present invention will be described with reference to FIG. FIG. 2 shows an image forming apparatus of a tandem system, which has an electrostatic adsorption belt as a transfer medium carrier, that is, a transfer conveyance belt 6, which includes a drive roller 92, an adsorption counter roller 91, a tension roller. It is suspended from 93. The transfer conveyance belt 6 is driven to rotate in the direction of the arrow by a drive roller 92.

  A yellow (Y), magenta (M), cyan (C), and black (K) image forming unit is disposed along the peripheral surface of the transfer / conveyance belt 6. It is sequentially conveyed to the forming unit. Each image forming unit includes a photosensitive drum 1 (1Y, 1M, 1C, 1K), a primary charger 2 (2Y, 2M, 2C, 2K), an exposure unit 3 (not shown) (3Y, 3M, 3C, 3K), A developing device 4 (4Y, 4M, 4C, 4K) and a drum cleaner 5 (5Y, 5M, 5C, 5K) are provided. These photosensitive drum 1, primary charger 2, developing device 4, and drum cleaner 5 are processes. The cartridge is integrated as a cartridge and is detachable from the main body of the image forming apparatus.

  A transfer roller 8 (8Y, 8M, 8C, 8K), which is a transfer charging unit, is in contact with the photosensitive drum 1 via a transfer conveyance belt 6, and the toner image on the photosensitive drum 1 is transferred to the transfer material 13. At this time, a transfer bias is applied to the transfer roller 8 from a transfer bias power source 10 (10Y, 10M, 10C, 10K) connected thereto.

  An optical sensor is provided in the vicinity of the transfer conveyance belt surface, and density control of each color component image, image writing position control, image position accuracy control, and the like are performed based on information from the optical sensor.

  The transfer material 13 is transported from the paper feed cassette 14 and the like toward the image forming unit by the pickup roller 15 and the paper feed roller, and is once sandwiched between a pair of registration rollers that are roller-like synchronous rotating bodies, and then the registration roller pair. In synchronism with the image forming operation on the photosensitive drum 1, the toner is supplied to the transfer material suction portion of the transfer conveyance belt 6.

  A suction roller 18 serving as a suction assisting unit is disposed in the suction portion so as to face the suction facing roller 91 via the transfer transport belt 6, and the transfer transport belt 6 and the transfer material 13 are sandwiched between the suction roller 18 and the facing roller 91. It is supposed to be. By applying a voltage (adsorption bias) to the adsorption roller 18 from an unillustrated adsorption bias power supply (high voltage power supply), the adsorption of the transfer material 13 to the transfer conveyance belt 6 is assisted. Here, some image forming apparatuses shown in FIG. 3 do not have a member such as a suction roller for assisting the suction of the transfer material onto the surface of the transfer conveyance belt.

  The transfer material 13 adsorbed on the transfer / conveying belt 6 in this manner sequentially passes through the image forming portions of the respective color components, and the yellow, magenta, cyan, and black of the photosensitive drums 1 (1Y, 1M, 1C, and 1K). The toner images of the respective colors are successively superimposed and transferred by the voltage (transfer bias) applied to the transfer roller 8 (8Y, 8M, 8C, 8K). Thereafter, the transfer material 13 is separated from the transfer conveyance belt 6 and sent to the fixing device 16, where four color toner images are fixed, and a full color permanent image is obtained on the transfer material 13. The transfer residual toner remaining on the photosensitive drum 1 (1Y, 1M, 1C, 1K) after the transfer is removed by the drum cleaner 5 (5Y, 5M, 5C, 5K).

  As a method for removing the density control pattern formed on the transfer / conveying belt and the toner transferred on the transfer / conveying belt at the time of image formation, voltage applied to the transfer roller 8 (8Y, 8M, 8C, 8K) ( The toner on the transfer / conveying belt is returned to the photosensitive drum 1 (1Y, 1M, 1C, 1K) by the cleaning bias, and further removed by the drum cleaner 5 (5Y, 5M, 5C, 5K). Here, as the cleaning bias, for example, the first and third image forming units (here, yellow and cyan image forming units) have + polarity, and the second and fourth image forming units (here, magenta and black image forming units). Then, the toner on the transfer conveyance belt can be effectively returned to the photosensitive drum 1 (1Y, 1M, 1C, 1K) by changing the polarity in each image forming unit so as to be negative.

  The above is the outline of the operation of the image forming apparatus using the transfer conveyance belt of the present invention. However, the seamless belt of the present invention can be applied to other than the image forming apparatus shown in FIG. In particular, even in the image forming apparatus in which the suction roller 18 is omitted from the image forming apparatus of FIG. 2, when the transfer / conveying belt of the present invention is used, good transfer medium transportability can be exhibited. Of course, the present invention can be applied to an image forming apparatus adopting a blade cleaning method or a brush cleaning method as a cleaning mechanism of the transfer conveyance belt, and is not limited thereto.

  Hereinafter, the present invention will be described in detail with reference to examples.

Example 1
Polyamide 6/10 resin 35% by mass
Polyamide 12 resin 35% by mass
Conductive carbon black 12% by mass
Copper iodide 0.1% by mass
Zinc oxide (powder resistance 1 × 10 ¹⁰ Ω · cm) 15.9% by mass
Potassium perfluorobutanesulfonate 2% by mass

  The above blend was melt-kneaded at 240 to 260 ° C. using a twin-screw extruder shown in FIG. 4, and thermoplastic resin composition pellets were obtained using a strand cutter (not shown). Here, the thermoplastic resin component and potassium perfluorobutanesulfonate, which is a fluorosurfactant, are introduced from the main hopper 41 shown in FIG. 4, and the conductive carbon black and zinc oxide are introduced from the sub hopper 42. Kneaded. Here, it is necessary to provide the sub hopper 42 at a position where the thermoplastic resin component is in a softened state. The obtained resin composition was extruded at 240 to 260 ° C. to produce a seamless belt having a thickness of 100 μm, a diameter of 140 mm, and a width of 250 mm. The obtained belt was evaluated by the following dielectric constant measurement, measurement of hydrogen bond component of surface energy, continuous image output test, and surface gloss measurement. Table 2 shows the measurement results and the evaluation results.

<Measurement of relative permittivity>
When the relative permittivity of the seamless belt obtained by the above-described method was measured, the maximum value of the relative permittivity of each part was 25.0, the minimum value was 24.3, and the average value was 24.7.

<Measurement of hydrogen bond component of surface energy>
When the hydrogen bond component of the surface energy was measured on the surface of the seamless belt obtained by the above method, it was 1.2 [mN / m].

<Continuous image output test>
An image output test was conducted with a seamless belt attached to the image forming apparatus shown in FIG. The image forming apparatus feeds back image density information and image position information read by the optical sensor 17 to the developing means, the exposure means, and the image writing position each time 1000 sheets pass, thereby controlling image density control and image positioning. It has a function of performing (color shift) control.

  Here, before the continuous paper passing test, 10 color misregistration measurement images as shown in FIG. 5 and a full color photographic image were output. The color misregistration amount was as good as 40 μm on average. It had sufficient paper adsorption power. In addition, a high-quality image was obtained even in a full-color photographic image.

Next, a continuous image output test of 10,000 sheets was performed, and the contamination (gloss) of the transfer / conveying belt surface before and after the endurance was measured to confirm the contamination due to paper dust. Gloss was measured using a Horiba IG-320 gloss checker when the gloss in the belt axis direction was measured at the same position as the relative permittivity measurement. The average was 77.8 in the initial stage and the average after the paper passing test. With 56.8, there is little loss of gloss due to endurance and density control can be performed well. After the endurance, the same photographic image as the initial output is output, and there is no change in color tone compared to the initial output. It was a thing. Here, Xerox 4024 75 g / m ² paper was used for image output.

  In the image output test results, the image quality was evaluated as follows. The results are shown in Table 4.

Image evaluation <Color shift: Adsorbability>
○: The average value is less than 80 μm Δ: The average value is 80 μm or more and less than 130 μm ×: The average value is 130 μm or more

  Here, the color misregistration depends on the transfer material adsorbing property of the transfer conveyance belt, and the color deviation of the output image becomes smaller as the transfer material adsorbing property of the transfer conveying belt is superior. In the present invention, those having a color misregistration evaluation result of Δ or more are regarded as actually usable levels.

<Image stability: paper dust contamination resistance>
○: The gloss retention on the surface of the transfer / conveying belt after endurance is 50% or more, and the color tone of the image hardly changes through the endurance of 10,000 sheets.
Δ: The gloss retention rate on the surface of the transfer / conveyance belt after endurance is 30% or more and less than 50%, and the change in color tone of the image after endurance of 10,000 sheets is slight, or the gloss retention rate is 50% or more, but the image is in durability Slightly inferior in stability.
X: The gloss retention on the surface of the transfer / conveyance belt after endurance is less than 30%, and the change in color tone of the image after endurance of 10,000 sheets is remarkably observed.

  Here, the image stability depends on the paper dust contamination resistance on the surface of the transfer / conveyance belt, and the transfer / conveyance belt having excellent paper dust contamination resistance is excellent in image stability. In the present invention, those having an image stability evaluation result of Δ or more are regarded as practically usable levels.

(Example 2)
A test similar to that in Example 1 was performed, except that the same transfer conveyance belt as in Example 1 was incorporated in the vertical conveyance type image forming apparatus having no suction roller shown in FIG. Similarly to the image forming apparatus of FIG. 2, this image forming apparatus feeds back image density information and image position information read by the optical sensor 17 to the developing means, the exposure means, and the image writing position each time 1000 sheets are passed. Thus, it has a function of performing image density control and image alignment (color shift) control. Table 4 shows the measurement results and the evaluation results.

(Examples 3 to 6, Comparative Example 1)
A seamless belt was produced by extrusion molding in the same manner as in Example 1. The surface of the obtained seamless belt was subjected to corona discharge treatment with varying treatment strength to produce a transfer / conveying belt subjected to surface modification treatment. Various tests were performed on the obtained transfer conveyance belt in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.

(Examples 7 to 10, Comparative Example 2)
A seamless belt was produced by extrusion molding in the same manner as in Example 1. The surface of the obtained seamless belt was subjected to ultraviolet irradiation treatment at different treatment strengths to produce a transfer / conveying belt subjected to surface modification treatment. Various tests were performed on the obtained transfer conveyance belt in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.

(Examples 11-14, Comparative Example 3)
Various tests were conducted in the same manner as in Example 2 except that the composition of the seamless belt was as shown in Table 1. Table 4 shows the measurement results and the evaluation results.

ここで、酸化亜鉛、チタン酸バリウムの粉体抵抗はそれぞれ１×１０^１０、２×１０^１２Ω・ｃｍであった。

Here, the powder resistances of zinc oxide and barium titanate were 1 × 10 ¹⁰ and 2 × 10 ¹² Ω · cm, respectively.

(Examples 15 and 16, Comparative Example 4)
A seamless belt was produced by extrusion molding in the same manner as in Example 12. The surface of the obtained seamless belt was subjected to corona treatment at different treatment strengths to produce a transfer / conveying belt subjected to surface modification treatment. Various tests were performed on the obtained transfer conveyance belt in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.

(Examples 17 and 18, Comparative Example 5)
Various tests were performed in the same manner as in Example 2 except that the composition of the seamless belt was as shown in Table 2. Table 4 shows the measurement results and the evaluation results.

ここで、酸化亜鉛の粉体抵抗は１×１０^１０Ω・ｃｍであった。

Here, the powder resistance of zinc oxide was 1 × 10 ¹⁰ Ω · cm.

(Example 19)
Except that the composition of the transfer / conveyance belt was changed as follows, a transfer / conveyance belt was prepared and various tests were conducted in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.
Poly 1,4-cyclohexylene dimethylene terephthalate resin 77.5% by mass
Conductive carbon black 12% by mass
Sodium dodecylbenzenesulfonate 0.5% by mass

( Reference Example 20)
Polyphenylene sulfide resin 88% by mass
Conductive carbon black 12% by mass
A resin composition was prepared in the same manner as in Example 1 except that the above blend was melt kneaded at 300 to 320 ° C. using a twin screw extruder. The obtained resin composition was extruded at 300 to 320 ° C. to produce a tubular film having a thickness of 100 μm, a diameter of 139 mm, and a length of 250 mm, and the obtained tubular film was as shown in FIG. By carrying out the treatment, a transfer conveyance belt was produced.

The following is a description of FIG.
(I) The tube-shaped film 200 is fitted to the outer periphery of the cylindrical inner mold 201 having an outer diameter of 140.0 mm, a thickness of 5.0 mm, and a length of 300 mm while extending the inner peripheral length.
(Ii), (iii) An inner diameter of 140.6 mm and a thickness of 3 mm obtained by applying and drying a sodium dodecylbenzenesulfonate aqueous solution on the inner surface of a cylindrical inner mold 201 having a thermoplastic endless film 200 fitted on the outer periphery. A cylindrical outer mold 202 having a length of 300 mm is disposed.
(IV) Heating to 250 ° C. in the state of (iii) to expand the aluminum cylindrical inner mold 201 having a large coefficient of thermal expansion, and heat the outer peripheral surface of the tubular film 200 to the inner peripheral surface of the cylindrical outer mold 202 The transfer conveyance belt is removed from the mold after pressure transfer and cooling.

  Various tests were performed on the obtained transfer conveyance belt in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.

(Example 21)
In Example 1, a transfer conveyance belt was produced in the same manner as in Example 1 except that the kneading method was changed as follows.

  All the compounding agents were charged from the main hopper 41 of the twin screw extruder shown in FIG. 4 and melt kneaded at 240 to 260 ° C. to obtain a resin composition. The obtained resin composition was extruded at 240 to 260 ° C. to produce a seamless belt having a thickness of 100 μm, a diameter of 140 mm, and a width of 250 mm.

  Various tests were performed on the obtained transfer conveyance belt in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.

(Comparative Example 6)
In Reference Example 20, a transfer conveyance belt was prepared and carried out in the same manner as in Reference Example 20, except that a fluorine-based release agent was applied instead of the sodium dodecylbenzenesulfonate aqueous solution as a material to be applied to the inner surface of the cylindrical outer mold. Various tests were performed in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.

  (Comparative Examples 7 and 8)

上記配合を、２軸押出機を用いて２８０〜３００℃で溶融混練することにより樹脂組成物を得た。混練時に、全ての配合剤を図４に示される２軸押出機のメインホッパー４１から投入することにより混練した。得られた樹脂組成物を２８０〜３００℃で押出成形することにより厚さ１００μｍ、直径１４０ｍｍ、幅２５０ｍｍのシームレスベルトを作製した。得られた転写搬送ベルトに関して実施例２と同様にして各種試験を行った。測定結果及び評価結果を表４に示す。

A resin composition was obtained by melt-kneading the above blend at 280 to 300 ° C. using a twin-screw extruder. At the time of kneading, all the compounding agents were kneaded by charging from the main hopper 41 of the twin screw extruder shown in FIG. The obtained resin composition was extruded at 280 to 300 ° C. to produce a seamless belt having a thickness of 100 μm, a diameter of 140 mm, and a width of 250 mm. Various tests were performed on the obtained transfer conveyance belt in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.

(Comparative Example 9)
Polycarbonate resin 85% by mass
Conductive carbon black 15% by mass
A resin composition was obtained by melt-kneading the above blend at 280 to 290 ° C. using a twin screw extruder. At the time of kneading, all the compounding agents were kneaded by charging from the main hopper 41 of the twin screw extruder shown in FIG. The obtained resin composition was extruded at 280 to 290 ° C. to produce a seamless belt having a thickness of 100 μm, a diameter of 140 mm, and a width of 250 mm. Various tests were performed on the obtained transfer conveyance belt in the same manner as in Example 2. Table 4 shows the measurement results and the evaluation results.

It is the schematic which shows the relative dielectric constant measurement position of a transfer conveyance belt. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. It is the schematic which shows an example of another image forming apparatus of this invention. It is the schematic which shows an example of the kneading apparatus (double-screw extruder) which can be used for this invention. It is the schematic which shows the color shift measuring method. It is process schematic which shows the post-processing method of the transfer conveyance belt of this invention.

Explanation of symbols

1 (1Y, 1M, 1C, 1K) Electrophotographic photoreceptor 2 (2Y, 2M, 2C, 2K) Primary charger 3 (3Y, 3M, 3C, 3K) Exposure means 4 (4Y, 4M, 4C, 4K) Development 5 (5Y, 5M, 5C, 5K) Drum cleaner 6 Transfer conveyor belt 8 (8Y, 8M, 8C, 8K) Transfer roller 91 Adsorption counter roller 92 Drive roller 93 Tension roller 10 (10Y, 10M, 10C, 10K) Transfer Bias power supply 13 Transfer material 14 Paper feed cassette 15 Paper feed roller 16 Fixing roller 17 Optical sensor 18 Adsorption roller 40 Twin screw extruder drive motor 41 Main hopper 42 Sub hopper 43 Twin screw extruder cylinder 44 Die 45 Resin composition 200 Tube shape Film 201 Cylindrical inner mold 202 Cylinder outer mold

Claims (12)

A transfer conveyance belt for conveying the electrostatically adsorbed recording medium to image transfer positions of a plurality of image forming units,
The transfer conveyance belt contains at least a thermoplastic resin and a conductive filler;
When the relative dielectric constant of the transfer / conveying belt is εb and the hydrogen bond component of the surface energy of the transfer / conveying belt is γb [mN / m], the following relationship is satisfied :
Transfer conveyor belt outermost surface of the transfer conveyor belt, characterized in that it have at least a surfactant.
15 ≦ εb ≦ 50
0.02 ≦ γb ≦ 30
5 ≦ (εb) ^1/2 + (γb) ^1/2 ≦ 10   The transfer / conveying belt according to claim 1, wherein a value obtained by dividing a maximum value of a relative dielectric constant at each part of the transfer / conveying belt by a minimum value is 2 or less. Wherein the surfactant is a fluorine-based surfactant, a transfer conveyor belt according to claim 1 or 2 is at least one hydrocarbon surfactant. The conductive filler, the transfer conveyor belt according to any one of claims 1 to 3, which is a conductive carbon black. The transfer conveyor belt, the transfer conveyor belt of claim 4 containing 5 to 20 wt% of the conductive carbon black. The transfer conveyor belt, the transfer conveyor belt according to any one of claims 1 to 5 containing further non-conductive fillers 5-20% by weight. Wherein the thermoplastic resin is a polyamide resin, a transfer conveyor belt according to any one of claims 1 to 6 either polyphenylene sulfide resin and alicyclic polyester resin. Transfer conveyor belt according to any one of claims 1 to 7, the surface of the transfer conveyor belt is treated surface modification. The transfer conveyance belt according to claim 8 , wherein the surface modification treatment is any one of an ultraviolet irradiation treatment, an electron beam irradiation treatment, a plasma treatment, a corona treatment, and an ozone treatment. An image forming apparatus having a transfer conveyance belt for conveying an electrostatically adsorbed recording medium to image transfer positions of a plurality of image forming units, and means for optically detecting a sample toner image formed on the transfer conveyance belt An image forming apparatus according to claim 1, wherein the transfer conveyance belt is the transfer conveyance belt according to any one of claims 1 to 9 . The image forming apparatus according to claim 10 , wherein the image forming apparatus does not have a member that assists the adsorption of the recording medium to the surface of the transfer conveyance belt. The image forming apparatus according to claim 10 or 11 having a cleaning mechanism for cleaning by the electric field of the surface of the transfer conveyance belt.

Images