JPH10186892A - Intermediate transfer body, its manufacture and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate transfer body, etc., capable of obtaining high glossiness, easily controlling the driving and the traveling of the intermediate transfer body while making the coefficient of friction low with a photoreceptor, and also reducing the transfer ratio of fogging toner so as to prevent image quality from being deteriorated in image formation in which a toner image is transferred and fixed to such a recording medium as a paper from the photoreceptor by using the intermediate transfer body. SOLUTION: A surface (image primary transfer surface) 24 to which the image of the intermediate transfer body is primarily transferred is a surface in which a protruding part 23 distinguishably scatters on a smooth surface 22. Relation between the area rate (Cin (%)) of the surface 22 on the surface 24 and the height (h(μm)) of the part 23 desirably satisfies an empirical formula h<=19.(1-Cin/100)<1/2> -24.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method employing a system in which a toner image formed on a photoreceptor is primarily transferred to an intermediate transfer member, and the primary transferred toner image is transferred and fixed on recording paper. The present invention relates to an intermediate transfer member, an image forming apparatus, and a method of manufacturing the intermediate transfer member, which are used in the method.

[0002]

2. Description of the Related Art An electrostatic latent image formed on a photoreceptor, which has been widely used, is developed as a toner image with dry toner, and then the toner image is electrostatically transferred to a recording medium.
In the image forming technique for fixing, there is a problem that density unevenness occurs in an image or powder toner is scattered in a transfer portion, resulting in inferior resolution and dot reproducibility.

[0003] This is largely due to the transfer process of electrostatically transferring the toner image on the photoreceptor to the recording medium.

Since the transfer efficiency of the toner layer depends on Et, if the Et is not constant regardless of the thickness of the toner layer, the unevenness of the recording medium represented by paper, and the unevenness of the electrical properties, the transfer efficiency will be reduced. It differs depending on the transfer position of the recording medium.
When the toner image formed on the photoreceptor is monochromatic and has a small layer thickness, image unevenness mainly occurs due to unevenness of a recording medium and unevenness of electrical properties. This is also true when a single-color toner image independently formed on a plurality of photoconductors is overlaid and transferred onto a single recording medium to form a color image. Causes image unevenness. In other words, the difference between the portion to be overprinted and the portion to transfer a single color without overlap transfer can be electrostatically suppressed, but it is difficult to compensate for unevenness of the recording medium and unevenness in electrical properties.

On the other hand, a single-color toner image independently formed on a plurality of photoconductors is transferred to an intermediate medium having uniform physical properties without unevenness, that is, a so-called intermediate transfer member (for example, a belt or a drum).
There is known a method in which the color image is transferred onto the recording medium by superimposing the color image on the recording medium. In this case, a uniform image without unevenness can be obtained on the intermediate transfer member. However, the toner image on the intermediate transfer member is multilayered, and has three or more layers at a large number and one layer or less at a small number. These toner layers are collectively electrostatically and uniformly applied to a recording medium represented by paper. It is difficult to apply a constant electric field to transfer
As a result, Et becomes non-uniform. Therefore, in this electrostatic transfer system, all of the color images superimposed on the intermediate transfer member are not transferred to the recording medium, but partially remain on the intermediate transfer member. Further, the residual amount differs depending on the thickness of the toner layer formed on the intermediate transfer member. Therefore, the color balance of the color image obtained on the recording medium shifts, and a desired color image cannot be obtained. In addition, a recording medium such as paper has irregularities on its surface.
The image does not adhere completely to the intermediate transfer member, causing an uneven gap. The transfer electric field is disturbed, the Coulomb repulsion between the powder toners is caused, and the toner is scattered, thereby deteriorating the image quality.

[0006] To solve this problem, Japanese Patent Publication No. 46-4167
No. 9 discloses a method in which a toner image formed on a photosensitive member is adhesively transferred to an intermediate transfer member, and then the toner is melt-transferred from the intermediate transfer member to a recording medium. In this method, since the transfer of the toner image to the recording medium is performed in a non-electrostatic manner, the deterioration of the image quality in the electrostatic transfer process as described above is less likely to occur.

[0007] For example, in Japanese Patent Application Laid-Open No. 2-108072, a toner image of a different color is electrostatically superimposedly transferred onto an intermediate transfer member, and a multi-color multiple toner image is fused on the intermediate transfer member. A technique is disclosed in which a fused multiple toner image is transferred to a recording medium to obtain a color copy.
According to this method, the transfer of the toner image to the recording medium is performed in a non-electrostatic manner, so that the image quality is hardly deteriorated as described above (this method is referred to as a transfer fixing method).

An image forming apparatus using this transfer fixing method is disclosed in US Pat. No. 2,990,278, Japanese Patent Laid-Open No. 5-1.
No. 9642, JP-A-5-107950, JP-A-5-249798, etc., the intermediate transfer body and the recording medium are adhered so that the transfer of the toner image from the intermediate transfer body to the recording medium is completely performed. After heating and pressurizing, cooling the toner until the cohesive force between the toners becomes larger than the adhesive strength between the toner and the intermediate transfer body (at least to the melting point or less), and then separating the recording medium from the intermediate transfer body. ing. According to this, it is possible to obtain a high-quality image having high transfer efficiency of toner, good color balance, high glossiness, and excellent toner transparency. In order to make effective use of this advantage, research has been continued on the structure of the uppermost layer of the intermediate transfer member.

For example, as a material having heat resistance and toner releasability, a silicone-based rubber, a fluorine-based resin, or a fluorine-based resin dispersed in a fluorine-based rubber as used in a conventional fixing device is used. Things are being considered.

In an apparatus using an intermediate transfer member, since the intermediate transfer member is in contact with the surface of the photoreceptor, a releasing agent such as silicone oil is applied to the surface of the intermediate transfer member as in a conventional fixing device. Can not give. Therefore, in order to prevent the toner image from being offset on the surface of the intermediate transfer member during transfer and fixing, and to reduce defects in image quality, the surface material of the intermediate transfer member has good releasability from toner. In many cases, a silicone rubber having advantages is used.

[0011]

However, even when an intermediate transfer member coated with silicone rubber is used, the following problems occur.

On the surface of the photoreceptor, there are a large number of isolated toners called fog toners, in addition to the toner image which is an image. When the toner image on the photoreceptor surface is directly transferred to the recording paper by using the electrostatic force, the selective transfer using the electrostatic force is performed on the fog toner, and the level is not recognized even when the toner image is transferred to the recording paper. However, when the above intermediate is used, the fog toner is almost completely transferred to the surface of the intermediate transfer member due to the elasticity and adhesiveness of the silicone rubber. As a result, there is a problem that image quality is reduced.

When a silicone-based rubber is used, if the toner image once melted is cooled to a temperature below the melting point and then peeled off, no offset phenomenon occurs on the surface of the intermediate transfer member. The toner image on the recording medium peeled off from the surface follows the surface shape of the intermediate transfer member. In other words, the surface of the toner image roughly captures the surface shape of the intermediate transfer body as if taking a mold. If the surface of the intermediate body is smooth, the toner image becomes extremely glossy, that is, the gloss becomes high. If the body surface is rough or cloudy, the gloss of the toner image is low. In order to obtain high gloss, it is necessary to keep the surface of the silicone rubber smooth.
This is because of the good leveling properties of silicone rubber.
It is easily achievable. However, another problem arises in that case. In other words, in order to copy and print a color image, toner images of three or more colors are superimposed to form a color. At that time, registration of each color, that is, misregistration has a significant effect on image quality. Then, the following problem occurs.

A smooth intermediate transfer member coated with a silicone rubber has a high coefficient of friction with a very smooth surface such as a photoreceptor. As a result, a slip occurs between a member (for example, a driving roll) for driving the intermediate transfer member and the back surface of the intermediate transfer member. Also, when the driving force is increased by increasing the coefficient of friction between the drive roll and the back of the intermediate transfer body,
The intermediate transfer body is good if the direction of the force received from the drive roll and the direction of the force received from the photoreceptor are good, but usually there is a problem of mechanical accuracy, and these directions do not exactly match. However, the intermediate transfer member is wavy from each other and cannot maintain a flat surface. As a result, there is a problem that the toner image on the surface of the photoreceptor cannot be transferred faithfully and an image defect occurs.

In general, to reduce the coefficient of friction of rubber,
A method of roughening the surface is used. Several methods are known. One of the methods is a method in which, in spray coating, the silicone rubber during spraying is hardly atomized, for example, by changing the coating conditions such as temperature, humidity, distance from a spray gun, and the viscosity of the silicone rubber, and roughening. . However, in this method, even if fine undulations appear, the surface of the undulations remains smooth, so that the coefficient of friction does not significantly decrease. The other is blasting, in which sand or steel grains are applied, and this method results in a general roughening of the rubber surface so as to form depressions. However, the coefficient of friction decreases only slightly, and the transfer rate of fog toner cannot be reduced. In addition, not only is the gloss of the image significantly reduced, but it is difficult to make the image uniformly rough, resulting in unevenness, and the image quality is greatly degraded. Other coating methods such as blade coater and dipping are also used, but even if both can produce large undulations, the surface will be like a mirror surface, and the inventors have paid attention to the problem of overcoming There is no solution.

There are several prior arts which describe the surface roughness of the intermediate transfer member. JP-A-59-50473 describes that the surface roughness is controlled by spray coating. However, the coefficient of friction with the photosensitive member is so large that it can be controlled by sliding the intermediate transfer member against the photosensitive member. It cannot be lowered nor can the transfer of fog toner be reduced to a level that cannot be recognized. In addition, JP-A-59-202377
JP-A-5-196442, JP-A-5-333711
JP-A-6-102782, JP-A-7-43992
And Japanese Patent Application Laid-Open No. H8-185061 exist, but the purpose is to improve the durability of the rubber on the surface of the intermediate transfer body, the transferability, the gloss of the image, the prevention of transfer omission, and the adhesion to the transfer material, The purpose is to regulate the surface roughness of the intermediate transfer member for the purpose of preventing the toner from being offset to the surface of the intermediate transfer member and for improving the preservability of the release member in order to prevent adverse effects of the release material such as oil. Even if the surface roughness disclosed in those publications is achieved, the intermediate transfer body which the present inventors have a problem with, a high gloss desirable as a color image, the influence on the image due to unevenness of the intermediate transfer body surface. It is demanded that the driving performance of the intermediate transfer member be improved without the visual observation and that the driving performance of the intermediate transfer member be improved (that is, the coefficient of friction with the photoreceptor be low) and that the transfer rate of fog toner be reduced. Be satisfied with everything Can not.

Accordingly, a first object of the present invention is to form an image forming apparatus for transferring and fixing a toner image from a photoreceptor to a recording medium using an intermediate transfer member having a surface such as silicone rubber in view of the above-mentioned drawbacks. In the apparatus, the image gloss can take a desirable high value for a color image, and the driving coefficient of the intermediate transfer member can be easily controlled by lowering the coefficient of friction with the photoreceptor, and the image quality deteriorates by reducing the transfer rate of fog toner. It is an object of the present invention to provide an intermediate transfer member capable of preventing the occurrence of an image.

A second object of the present invention is to provide a suitable method for producing the intermediate transfer member.

A third object of the present invention is to provide an image forming apparatus using the intermediate transfer member.

[0020]

The first object can be achieved by the following intermediate transfer member. That is, the photoreceptor on which the electrostatic latent image is formed is developed with a developer containing toner, the developed toner image is primarily transferred to an intermediate transfer member, and then the primary-transferred toner image is
An intermediate transfer member used in an image forming method in which a toner image is transferred to a recording medium by heating at least by contacting the recording medium, and a surface on which the image is primarily transferred (hereinafter, also referred to as an image primary transfer surface) is The intermediate transfer member is a surface in which convex portions are provided on a smooth surface, and the surfaces (the smooth surface and the convex portions) are scattered so as to be distinguishable.

In the present invention, "the smooth surface and the convex portion can be distinguished" means that when the enlarged image or the enlarged photograph of the image primary transfer surface is observed, the smooth surface and the convex portion are objectively determined. It means that it can be distinguished (that is, a person skilled in the art can practically arbitrarily recognize the existence of the two types). This point is applicable everywhere in the observation target area. Therefore,
The primary transfer surface of the image according to the present invention can be distinguished from unevenness, but is clearly different from a surface where a smooth surface is not clear, that is, a surface where the surface is sandblasted.

According to the present invention, since the individual projections present on the image primary transfer surface are scattered, the image transferred from the surface to the recording medium is less affected by the projections (ie, The concave portions of the transferred image corresponding to the convex portions become invisible), and have high gloss. On the other hand, the friction between the intermediate transfer member and the photoreceptor is reduced by the convex portion,
Further, transfer of fog toner is also prevented. As a result, the above object can be achieved.

The first object described above can also achieve the following invention by the same or similar operation.

That is, in the intermediate transfer member used in the image forming method, the surface onto which the image is transferred is a surface on which a convex portion is formed on a smooth surface and these are scattered so as to be distinguishable. The relationship between the ratio [Cin (%)] of the area of the smooth surface of the intermediate transfer member surface and the height [h (μm)] of the convex portion is determined by the empirical formula h ≦ 19 · (1−Cin / 100) ^{−1 /} satisfies ² -24.5 (1), the height of the convex portion, the intermediate transfer member is 2μm or more. Cin is, for example, 50 to 95%.

In the intermediate transfer member used in the image forming method, the surface onto which the image is to be transferred is a surface having a smooth surface on which projections are scattered. The intermediate transfer member, wherein the image primary transfer surface has a coefficient of friction lower than the coefficient of friction in the absence thereof.

The second object is the above-mentioned method for producing an intermediate transfer member, wherein before the surface of the intermediate transfer member is finally cured, a surface corresponding to a surface on which an image is primarily transferred is formed on the surface. This can be achieved by a manufacturing method including a step of pressing a mold having the same.

The third object is to provide a photoreceptor, a developing machine for supplying a developer containing toner to the photoreceptor, an intermediate transfer member in contact with the photoreceptor, and a recording medium in which a recording medium is fed into contact with the intermediate transfer member. Medium transporting means, at least comprising a heating means for heating the contact portion, forming an electrostatic latent image on the photoreceptor using light, and developing the electrostatic latent image with a developer containing toner, The developed toner image is primary-transferred to an intermediate transfer member, and thereafter, the primary-transferred toner image is
In an image forming apparatus that performs an image forming method of transferring a toner image to a recording medium by heating at least in contact with a recording medium, the surface on which the image of the intermediate transfer body is primarily transferred has a convex portion on a smooth surface, Make them distinguishable,
This can be achieved by an image forming apparatus that is a scattered surface.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

FIG. 1 is a schematic view illustrating an embodiment of the present invention and schematically shows an intermediate transfer member according to the present invention and an image forming apparatus using the same.

The intermediate transfer member 50 has a belt shape and has a two-layer structure of a base layer and a surface layer. Materials that can be used as the base layer (substrate) of the intermediate transfer member include polyimide, polyetheretherketone (PEEK), polyarylene sulfide (PAS), polyimideamide, polyethersulfone, (PES), and polyethernitrile ( PE
N) and thermoplastic polyimides. Polyimides are preferred from the requirements of heat resistance and mechanical strength.

The surface layer preferably has a volume resistivity of 10 ¹² Ωcm to 10 ¹⁵ Ωcm in order to electrostatically transfer the toner image from the photosensitive member to the intermediate transfer member without image disturbance.

When simultaneous transfer and fixing from the intermediate transfer member to a recording medium (paper or the like) is performed, the adhesion between the intermediate transfer member and the recording medium is improved by sandwiching the toner image, and the releasing property and heat resistance of the toner are taken into consideration. The surface layer is preferably a silicone rubber coat layer. However, in some cases, a fluorine-based resin or a coating layer in which a fluorine-based resin is dispersed in a fluororubber can be used. Usually, the rubber hardness of the surface layer is 20 to 70.
The thickness is set to 20 to 300 μm.

In FIG. 1, a belt-like intermediate transfer member 50 is shown.
Are arranged horizontally by the rollers 5-1 and 5-2 positioned above and below the rollers 5-1 and 5-2, and the rollers 5-1 and 5-2 are separated from each other. It is supported by a heating roll 2 whose diameter is substantially equal to the distance between the highest point and the lowest point, and is rotatable in the direction of the arrow. An intermediate transfer member is held between the heating roll 2 and the pressing roll 3.
Are arranged facing each other. As the heat and pressure roll, a metal roll or a roll having a heat-resistant elastic layer such as silicone rubber on a metal roll can be used. A heat source is arranged inside the heating roll, and the heating temperature is
The toner temperature in the heating area is set and controlled so as to be equal to or higher than the toner melting temperature. The heating roll 2 and the pressure roll 3 can be arranged in reverse, and the pressure roll 3 may be a heating roll having a heat source inside.

The drum-shaped photoconductors 1-1, 1-2, 1-3, and 1-4 are arranged in parallel in contact with and facing the surface of the upper transfer surface of the intermediate transfer member 50 and along the belt movement direction. The chargers 10-1 and 10-
It can be uniformly charged by 2, 10-3, and 10-4. As the photoconductors 1-1, 1-2, 1-3, and 1-4, various organic photoconductors can be used in addition to various inorganic photoconductors (Se, a-Si, a-SiC, CdS, and the like). it can.

Light beam scanning device 2 for turning on / off each photosensitive member by a light beam pulse width modulator in response to a density signal
0 are located across each photoreceptor. Developing units 11, 12, 13, and 14 containing black, yellow, magenta, and cyan toners are arranged on each photoconductor, respectively. The color toner is formed of a thermoplastic binder containing a dye such as yellow, magenta, and cyan, and a known material can be used. The amount of toner on the recording paper of each color is about 0.4 m depending on the content of the dye.
g / cm ² ~0.7mg / cm ² to become such, the exposure condition or the developing conditions are set.

Each photoconductor 1-1, 1-2, 1-3, 1-4
Below, through the intermediate transfer member 50, the transfer device 50-1,
50-2, 50-3, and 50-4 are arranged.

Between the pressure roll 2 and the pressure roll 3,
The recording paper P from the tray 6 can be sent.

Recording paper sandwiched between pressure roll 2 and pressure roll 3
The holding section (nip), that is, the heating area,
The intermediate transfer body 50, the toner image, and the recording paper P are sufficiently dense.
No partial lifting occurs and the recording paper P does not wrinkle
Is set so that this does not occur. The nip pressure is
1 × 10 for the above toner^Five Pa-1 × 10 ⁶ 
The range of Pa is appropriate.

Immediately after passing through the heating area, a heating area exit cooling device 7 facing the recording paper P is provided. The heating area exit cooling device 7 is for the purpose of lowering the toner temperature immediately after passing through the heating area, and the same effect can be obtained by cooling not only from the paper side but also from the intermediate transfer body immediately after passing through the heating area. The same is true even when cooling is performed immediately after passing through the heating region from both sides. By cooling, the cohesive force of the toner is increased to prevent the toner from being offset to the intermediate transfer body 50 during peeling.

The cooling device 4 arranged below the lower moving surface of the intermediate transfer member cools the intermediate transfer member 50 and the recording paper P which are conveyed integrally from the heating area.

The device having the above configuration functions as follows. Each photoconductor is exposed by the light beam scanning device 20 according to an image signal, and an electrostatic latent image is formed. The electrostatic latent images on the respective photoconductors are developed by developers 11, 12, 13, and 14 containing black, yellow, magenta, and cyan toners, respectively.
And a toner image of each color of a so-called digital image representing the density by area modulation is formed on each photoconductor. The toner images of the respective colors are sequentially transferred to the transfer units 50-1 and 50.
According to -2, 50-3, and 50-4, primary transfer is performed to the intermediate transfer member 50, and a plurality of color toner images are formed on the intermediate transfer member 50.

The pressure roll 3 is provided with the recording paper P from the tray 6.
Is pressed against the heating roll 2 with the paper feeding. Thereafter, the intermediate transfer member 50 holding the plurality of color toner images and the recording paper P
However, the heating roll 2, the pressure roll 3
And heated under pressure. The toner heated above the melting temperature is softened and melted, penetrates into the recording paper P, and then solidifies, whereby transfer and fixing are performed.

The intermediate transfer body 50 and the recording paper P cooled by the heating area outlet cooling device 7 and the cooling device 4 are conveyed, and the recording paper P is hardened by the roll 5-2 having a small radius of curvature. As a result, the toner is separated from the intermediate transfer member 50 together with the toner, and a color image is formed. The surface of the toner image transferred and fixed on the recording paper P is
The surface is smoothed and has a high gloss.

The image primary transfer surface of the intermediate transfer member according to the present invention, which is used in the image forming apparatus as described above,
The convex portions are scattered on the smooth surface. Then, the intermediate transfer member is defined by a combination of requirements in the following description.

The smooth surface and the convex portions on the image primary transfer surface are scattered so as to be distinguishable. In addition, due to the presence of the protrusion, the coefficient of friction in the absence of the protrusion,
The image primary transfer surface has a low coefficient of friction.

The height of the projection is preferably 2 μm or more,
It is 12 μm or less, more preferably 3 μm or more and 9 μm or less.

The interval between the convex portions is preferably
10 μm or more and 200 μm or less.

Further, the ratio [Cin (%)] of the area of the smooth surface on the image primary transfer surface and the height [h (μ
m)] preferably satisfies the empirical formula h ≦ 19 · (1−Cin / 100) ^−1/2 −24.5 · (1) (see Examples below).

The shape and arrangement pattern of the projections are not limited, and various patterns can be employed, including those with and without order. For example, the patterns are as shown in FIGS.

FIG. 2 is a cross-sectional view of the intermediate. In this intermediate, a silicone rubber 24 having a smooth portion 22 and a convex portion 23 is provided on a base layer 21. Other FIGS. 3 to 7
FIG. 4 is a diagram showing a pattern of a convex portion as viewed from above. As shown in FIG. 3 or 4, the convex portions may be isolated (FIG. 3 shows a pattern in which each column and each row of the convex portions have the same pattern, and FIG.
Indicates a pattern in which the convex portions are shifted every other line),
As shown in FIGS. 5 to 7, it may be linear (FIG.
Is a line perpendicular to the longitudinal direction of the intermediate body, FIG. 6 is a line parallel to the direction, and FIG. 7 is a pattern of a line oblique to the direction).

It is preferable that the heights of the projections are as uniform as possible, but it is not always necessary.

To obtain the intermediate transfer member of the present invention, any method can be used. For example, the intermediate transfer member can be prepared by embossing. For example, a mold in which fine recesses are formed on a smooth surface by processing metal may be used, but the following method can also be preferably used.

As shown in FIG. 8, a toner image 81 having no toner at the position corresponding to the convex portion of the intermediate transfer member (resulting in a concave portion) is transferred and fixed to a recording medium (paper or the like) 82, and the recording is performed. In this method, the medium 82 is used as an embossing die and is pressed against an intermediate transfer body before curing (that is, an intermediate transfer body before rubber or resin is hardened).

At this time, the interval between the concave portions, the depth of the concave portions, and the size of the concave portions are created by changing the number of times of overlapping the toner, the number of lines / inch, and the area ratio of the toner image. For example, if a convex portion is formed on the surface of the intermediate transfer member by using a paper type in which the toner is one line, 200 lines / inch, and the area ratio of the toner image is 85%, the convex portion on the surface of the intermediate transfer member depends on the conditions of transfer and fixing. Height is 3 μm to 4 μm, interval is 100 μm
And the area ratio of the smooth portion can be changed from 85% to 90%. At this time, the roughness of the smooth portion is 0.10.
μmRa, and from FIG. 9, the gloss of this smooth portion alone is 1
Over 00%.

The intermediate transfer member can be a drum or the like in addition to the belt.

[0056]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples and comparative examples on which the invention was completed.

In these examples, an 80 μm-thick polyimide film to which carbon black was added was used for the base layer of the belt-shaped intermediate transfer member, and the toner image was electrostatically transferred from the photosensitive member to the intermediate transfer member without image disturbance. For this purpose, the volume resistivity of the base layer was adjusted from 10 ⁸ Ωcm to 10 ¹² Ωcm by changing the amount of carbon black added.

The surface layer of the intermediate transfer member was coated with a 50 μm-thick silicone-based rubber (specific materials will be described later) on the base layer.

The amount of each color toner used on the recording paper was set so that the content of each dye was 0.65 mg / cm ² .

The device used is a device substantially corresponding to the device shown in FIG. As a roll corresponding to the heating / pressing roll shown in FIG. 1, a 3 mm-thick silicone rubber having a hardness of 55 was laminated on a hollow aluminum roll, and a halogen lamp was used as a heat source inside the heating roll. used. The nip pressure is 5.5 × 10
^It was set to ⁵ Pa. [Comparative Example] The present inventors first made the surface of the intermediate transfer member uniform and examined the relationship between the surface roughness and the gloss. As a method of uniformly roughening the silicone rubber surface,
A member having a uniform roughness on the surface of the silicone rubber, in fact, a stamping method of pressing a wrapping film (trade name: Imperial Wrapping Film, manufactured by Sumitomo 3M) (that is, a method of projecting the surface of the wrapping film onto the silicone rubber surface) Tried).

Specifically, a silicone rubber having a rubber hardness of 40 Hs (trade name: silicone rubber KE4895, manufactured by Shin-Etsu Chemical Co., Ltd.) and a silicone rubber having a rubber hardness of 65 Hs (prototype, Dow Corning Toray Co., Ltd.) (Silicone Co.) was coated to a thickness of about 50 μm, a wrapping film was placed on the surface before cross-linking, and after a certain period of time, peeled off, and the remaining cross-linking steps were performed. At that time, by changing the number of the wrapping film, the timing of mounting on the silicone rubber surface, the time, and the like, intermediate transfer members having various surface roughnesses were prepared. FIG. 9 shows the result of examining the relationship between the gloss and the roughness of the image using the intermediate transfer member created by such embossing.

Here, the apparatus used for image formation and evaluation will be specifically described. Evaluation copier Product name: Acolor 935, toner manufactured by Fuji Xerox Co., Ltd. Toner for Acolor 935, paper manufactured by Fuji Xerox Co., Ltd. Product name: J-coated paper, gloss meter Gloss Meter Model GM-26D for 26, manufactured by Fuji Xerox Co., Ltd. Surface roughness meter Profile Micrometer VF7500 / 7510 manufactured by Murakami Color Research Laboratory, 75 ° manufactured by Keyence FIG. 9 shows that there is not much difference in gloss due to the difference in hardness of silicone rubber. This is presumably because the recording paper on which the toner image has been transferred and fixed is cooled and then peeled off from the intermediate transfer member.

Incidentally, it is said that a desirable high gloss for a color image is 70% or more. According to FIG. 9, when the entire surface of the intermediate transfer member is uniformly roughened, the surface roughness is smaller than Ra 0.3 μm. There must be.

Next, the friction coefficient of the embossed intermediate transfer member with the photoreceptor is shown in FIG. in this case,
A difference occurs depending on the rubber hardness, and the higher the rubber hardness, the lower the friction coefficient. This is because low rubber hardness tends to cause deformation when pressure is applied. The friction coefficient measuring device used was Peeling / Slipp manufactured by Heidon.
ing / Scratching Tester Hei
don-14. The speed was 100 mm / sec, and the load was 10 gf / mm.

Here, the allowable range of the friction coefficient between the intermediate transfer member and the photosensitive member will be described. FIG. 11 is an explanatory diagram showing the relationship between the photoreceptor 111, the intermediate transfer belt 112, and the forces acting on the intermediate transfer member drive roll 113 for driving the intermediate transfer belt 112. There is a limit in mechanical working accuracy, and a speed difference occurs between the speed of the surface of the photoconductor 111 and the moving speed of the intermediate transfer belt 112, and the speed of the photoconductor 111 and the driving roll 11
The situation when an error occurs with respect to the parallelism 3 is shown.

A friction coefficient μ between the photoconductor 111 and the intermediate transfer belt 112 is provided between the photoconductor 111 and the intermediate transfer belt 112.
And a transfer pressure Fn.
Here, the transfer pressure Fn is the sum of the electrostatic attraction force and the mechanical pressing force accompanying the transfer, and is generally at least 0.5 g / m2.
It is said to require a value of m ² . Further, between the back surface of the intermediate transfer member belt 112 and the intermediate transfer member driving roll 113,
A conveying force Fd for moving the intermediate transfer belt 112 acts. On the other hand, the intermediate transfer belt 112 itself has a bending rigidity Fr.

When the belt bending stiffness Fr is sufficient,
If the frictional force Fs is larger than the transporting force Fd, a slip occurs between the intermediate transfer member driving roll 113 and the back surface of the intermediate transfer member belt 112, and the moving speed of the intermediate transfer member belt 112 becomes uncontrollable, and the image expands and contracts. A color overlay shift will occur.

On the other hand, when the conveying force Fd is sufficient with respect to the frictional force Fs, but the belt bending rigidity Fr is insufficient, the intermediate transfer belt 112 is wavy, and the moving speed of the intermediate transfer belt 112 is reduced. Control becomes impossible, and the image expands / contracts or the color overlap shifts.

FIG. 12 shows whether control is actually performed when the friction coefficient μ between the photosensitive member and the intermediate transfer member (belt), the thickness of the belt, and the like are changed. From this, when the belt is thin and the rigidity is small, the threshold value is determined by the waving of the belt, and when the belt bending rigidity is increased by the thickness of the belt, the threshold value is determined by the slip of the intermediate transfer member driving roll. However, it can be seen that control is not possible unless the friction coefficient is 1.2 or less. Note that this result indicates the transfer pressure Fn
Is the minimum value of 0.5 g / mm ² , and it is desirable that the friction coefficient is small.

Therefore, from FIG. 10 in which the coefficient of friction of the embossed intermediate transfer member with the photoreceptor was examined, it was found that in order to reduce the value to 1.2 or less, the surface roughness of the intermediate transfer member slightly changed depending on the rubber hardness. The height needs to be larger than 0.5 μm Ra.

FIG. 13 shows the results of examining the fog toner transfer rate of the embossed intermediate transfer members. The hatched portion in the figure indicates the transfer rate when the toner image on the photoconductor is directly transferred onto the recording medium by electrostatic transfer in the related art. Therefore, the surface of the intermediate transfer member must have a roughness of about 0.6 μm Ra or more in order to make it comparable to the conventional one.

From the above results, when the surface of the intermediate transfer member is made uniform and the surface roughness is made 0.6 μm Ra or more, the friction coefficient is 1.2 or less and the fog toner transfer rate is equal to or less than that of the conventional electrostatic transfer. Can be achieved, but gross is reduced to 40%
It turned out to be below. [Examples (some control examples)] As a result of the above, the present inventors
An attempt was made to roughen the surface of the intermediate transfer member without leaving it smooth, instead of uniformly roughening the surface. That is, by leaving a smooth high gloss surface at a high area ratio on the surface of the intermediate transfer member, a high gloss of 70% or more is obtained. To reduce the friction coefficient and the fog toner transfer rate.

Here, it must be taken into consideration that in the image on the recording medium, the convex portion on the surface of the intermediate transfer member forms a concave portion on the surface of the toner image. Usually, in order to prevent the visual function (VT) shown in FIG.
According to FIG. F), at least 150 lines / inch or more is required. That is, the interval between the convex portions is preferably 170 μm or less. However, as a result of a sensory evaluation as an interval that does not matter even if visually recognized, it was found that the interval may be about 200 μm. Thus, FIG. 15 shows the result of evaluating how much the area of the smooth portion should be actually increased to increase the gloss of the image to 70% or more by changing the height of the convex portion. As a result, in practice, an intermediate transfer body coated with silicone rubber having a rubber hardness of 40 Hs was prepared using a recording paper having the above-described toner image as a mold, and the area of the smooth portion and the height of the convex portion were changed. The image was obtained by transferring and fixing the image on recording paper and measuring the gloss.

FIG. 15 shows that the relationship between the height of the convex portion and the area ratio of the smooth portion should be higher than the solid line in FIG. 15 in order to obtain the desired high gloss for the color image. .

The relationship between the area ratio of the smooth portion and the height of the convex portion is represented by the following equation. Height of convex portion [h] ≦ 19 · (1−Cin / 100) ^−1/2 −24.5 Expression (1) Unit of height of convex portion: μm Unit of Cin:% For example, smooth portion If the area ratio (Cin) is 85%, the height (h) of the convex portion may be about 10 μm or less.

Although the interval between the projections cannot be changed greatly due to the conditions for forming the mold for embossing the surface of the intermediate transfer member, the size of the projection is 120 μm.
From m to about 200 μm, there was no significant difference in the relationship between the gloss value and the area ratio of the smooth portion and the height of the convex portion in FIG.

Next, FIG. 16 and FIG. 17 show measurement results of the other two required items, that is, the coefficient of friction with the photosensitive member and the transfer rate of the fog toner. These are 40Hs and 65
In the intermediate transfer member of the silicone rubber surface of Hs, the coefficient of friction with the photoreceptor and the fog were determined using the intermediate transfer member in which convex portions of various heights were formed with the area ratio of the smooth portion between 55% and 95%. This is a measurement of the toner transfer rate.

From FIG. 16, the coefficient of friction with the photoreceptor originally depends on the area ratio of the smooth portion. From this measurement, when the area ratio of the smooth portion is 55% to 95%, if the height of the convex portion is 2 μm or more, , The coefficient of friction was found to be 3.0 or less.

The fact that the area ratio of the smooth portion is 0.55 or more means that the area ratio of the convex portion is 0.45 or less. Since the contact area is about 1/3, the coefficient of friction should simply be reduced to about 1/3 of the smooth surface, but it is considered that the cause of the fact that this was not the case is the deformation of the silicone rubber. From the viewpoint of driving and driving control of the intermediate transfer member, the friction coefficient is required to be 1.2 or less. It turned out to be good.

From the experimental results, it was found from the experimental results that the fog toner transfer rate was not significantly affected by the area ratio of the smooth portion if there were some protrusions, and the conventional electrostatic force was used if the height of the protrusions was also 2 μm or more. It was found that the transfer rate was lower than or equal to the transfer rate in the case of direct transfer to a recording medium. The average particle size of the color toner used this time is about 7 μm, and it comes into contact with the concave smooth portion. Nevertheless, the reason why the transfer rate of the fog toner decreased was that the pressure applied to the fog toner from the smooth portion of the intermediate transfer member was reduced due to the presence of the convex portion. May be stronger than the adhesive force with the surface of the intermediate transfer member,
It is considered that the transfer rate of the entire fog toner was reduced.

From the above results, when the friction coefficient between the intermediate transfer member and the photoreceptor is reduced (in this embodiment, 1.2 or less), a smooth portion is provided on the silicone rubber on the surface of the intermediate transfer member. A convex portion having a height of 2 μm or more is provided there, and the formula (1)
The height of the convex portion and the area ratio of the smooth portion may be determined so as to satisfy the following. By doing so, the gloss of the image is high, and the transfer rate of the fog toner can be made equal to or less than the transfer rate in the case of direct transfer to the recording medium by the conventional electrostatic force.

Although the gloss desired for a color image is set to 70%, for example, if 60% can be tolerated, the relationship between the area ratio of the smooth portion and the height of the convex portion in FIG.
The required area ratio of the smooth portion and the height of the convex portion may be obtained.

The present invention is not limited by the above embodiments, but should be determined by the gist of the present invention and its idea.

[0084]

According to the present invention, in image formation in which a toner image is transferred and fixed from a photoreceptor to a recording medium using an intermediate transfer member, a desired high gloss as a color image can be obtained, and the intermediate transfer is performed to prevent image displacement. Driving controllability of the body can be maintained well. In addition, the transfer rate of the fog toner on the photosensitive member can be reduced to a level equal to or less than the conventional direct transfer to the recording medium by the electrostatic force.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus using an intermediate transfer member according to the present invention.

FIG. 2 is a schematic sectional view of an example of an intermediate transfer member according to the present invention.

FIG. 3 is a schematic plan view of an example of an intermediate transfer member according to the present invention.

FIG. 4 is a schematic plan view of another example of the intermediate transfer member according to the present invention.

FIG. 5 is a schematic plan view of still another example of the intermediate transfer member according to the present invention.

FIG. 6 is a schematic plan view of another example of the intermediate transfer member according to the present invention.

FIG. 7 is a schematic plan view of still another example of the intermediate transfer member according to the present invention.

FIG. 8 is a schematic diagram showing an example of a mold for embossing the surface of an intermediate transfer member so that convex portions are scattered on smooth portions.

FIG. 9 is a diagram showing the relationship between the roughness of the surface of an intermediate transfer member provided with unevenness and the image gloss.

FIG. 10 is a diagram showing the relationship between the roughness of the surface of an intermediate transfer member provided with unevenness and the coefficient of friction.

FIG. 11 is a schematic diagram illustrating a relationship between forces acting on an intermediate transfer member and an intermediate transfer member driving roll that drives the intermediate transfer member.

FIG. 12 is a diagram illustrating a relationship between the running controllability of the intermediate transfer member and the friction coefficient between the intermediate transfer member and the photoconductor when the friction coefficient is changed.

FIG. 13 is a diagram showing the relationship between the roughness of the surface of an intermediate transfer member provided with uniform unevenness and the transfer rate of fog toner.

FIG. 14 is a diagram showing a relationship between a spatial frequency and a visual function value.

FIG. 15 is a diagram showing the relationship between the area ratio of the smooth portion on the surface of the intermediate transfer body and the image gloss when the height of the convex portion on the surface is changed so that the convex portions are scattered in the smooth portion. It is.

FIG. 16 is a diagram showing the relationship between the height of the protrusions on the surface of the intermediate transfer member and the coefficient of friction, in which the protrusions are embossed in the smooth portion.

FIG. 17 is a diagram illustrating a relationship between the height of the convex portion on the surface of the intermediate transfer member and the transfer rate of fog toner, which is embossed so that the convex portion is scattered in the smooth portion.

[Explanation of symbols]

1 1-1, 1-2, 1-3, 1-4 Photoconductor 2
Heating roll 3 Pressure roll 4 Cooling device 5
0 Intermediate transfer member 5-1, 5-2, 5-3 Roll 6
Paper tray 7 Heating area exit cooling device 10-1, 10-2, 10-3, 10-4 Charger 11, 12, 13, 14 Developing device 20 Exposure device P Recording paper

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Riki Ando 430 Green Tech Nakai, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. Inside (72) Inventor Kaku Kitano 430 Green Tech Nakai, Nakaicho, Ashigarakami-gun, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. 72) Inventor Yasuo Sakaguchi 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd.

Claims (18)

[Claims] 1. A photoconductor on which an electrostatic latent image is formed is developed by a developer containing toner, and the developed toner image is primarily transferred to an intermediate transfer member. An intermediate transfer member used in an image forming method in which an image is brought into contact with a recording medium and at least a toner image is transferred to the recording medium by heating, and the surface on which the image is primarily transferred has a smooth surface with convex portions. , An intermediate transfer member, which is the surface on which they are distinguishably scattered. 2. The height of the projection is 2 μm or more and 12 μm or more.
2. The intermediate transfer member according to claim 1, wherein m is equal to or less than m. 3. An interval between the convex portions is not less than 10 μm and not more than 20 μm.
3. The intermediate transfer member according to claim 2, which has a thickness of 0 μm or less. 4. The relationship between the ratio [Cin (%)] of the area of the smooth surface on the surface on which the image is primarily transferred and the height [h (μm)] of the convex portion is determined by an empirical formula h ≦ 19 · The intermediate transfer member according to claim 2, wherein (1-Cin / 100) ^-1/2 -24.5 (1) is satisfied. 5. The intermediate transfer member according to claim 4, wherein said Cin is 50 to 95%. 6. The gloss of the surface on which the image is primarily transferred is 6
The intermediate transfer member according to claim 5, wherein the amount is 0% or more. 7. The gloss of the surface on which an image is primarily transferred is 7
The intermediate transfer member according to claim 5, wherein the amount is 0% or more. 8. The intermediate transfer member according to claim 1, wherein the surface on which the image is primarily transferred is made of a silicone rubber. 9. A photoconductor on which an electrostatic latent image is formed is developed by a developer containing toner, and the developed toner image is primarily transferred to an intermediate transfer member. An intermediate transfer member used in an image forming method in which an image is brought into contact with a recording medium and at least a toner image is transferred to the recording medium by heating, and the surface on which the image is primarily transferred has a smooth surface with convex portions. , Which are scattered so that they can be distinguished, and the ratio [Cin (%)] of the area of the smooth surface on the surface on which the image is primarily transferred and the height [h (μm)] of the convex portion Satisfies the empirical formula h ≦ 19 · (1−Cin / 100) ^−1/2 −24.5 (1), and the height of the convex portion is 2 μm or more. 10. The intermediate transfer member according to claim 9, wherein said Cin is 50 to 95%. 11. A photoconductor on which an electrostatic latent image is formed is developed by a developer containing toner, and the developed toner image is primarily transferred to an intermediate transfer member, and thereafter, the transferred toner image is transferred. Is brought into contact with a recording medium, an intermediate transfer member used in an image forming method of transferring a toner image to the recording medium by heating at least, the surface on which the image is primarily transferred has a smooth surface with convex portions, An intermediate transfer member, wherein the surface to which the image is transferred has a friction coefficient smaller than a friction coefficient in a case where the surface is not present due to the presence of the protrusion. 12. The intermediate transfer member according to claim 11, wherein the smooth surface and the convex portion are scattered so as to be distinguishable. 13. The relationship between the ratio [Cin (%)] of the area of the smooth surface on the surface on which the image is primarily transferred and the height [h (μm)] of the convex portion is determined by an empirical formula h ≦ 19 · (1) -Cin / 100) ^-1/2 -2
The intermediate transfer member according to claim 12, which satisfies 4.5. 14. The intermediate transfer member according to claim 13, wherein the height of the projection is 2 μm or more. 15. The intermediate transfer member according to claim 14, wherein the Cin is 50 to 95%. 16. The method for producing an intermediate transfer member according to claim 1, wherein the surface of the intermediate transfer member has a surface corresponding to a surface on which an image is primarily transferred before the surface is finally cured. A method for producing an intermediate transfer member having a step of pressing a mold. 17. The method according to claim 16, wherein the mold comprises a recording medium and a toner image transferred to the surface of the recording medium. 18. A photoreceptor, a developing machine for supplying a developer containing toner to the photoreceptor, an intermediate transfer member in contact with the photoreceptor, a recording medium conveying means for sending a recording medium to and contacting the intermediate transfer member, At least heating means for heating the contact portion, forming an electrostatic latent image on the photoconductor using light, developing the electrostatic latent image with a developer containing toner, and developing the developed toner. Primary transfer of the image to the intermediate transfer body, after that, the primary transferred toner image, in contact with the recording medium, in an image forming apparatus that performs an image forming method of transferring the toner image to the recording medium by at least heating, An image forming apparatus in which the surface of the intermediate transfer body on which an image is primarily transferred is a smooth surface having convex portions scattered so as to be distinguishable.