JPH0378624B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intermediate device used for transferring a toner image on an image carrier such as a photoreceptor drum and further transferring this transferred toner image to a next transfer material such as a recording material. The present invention relates to transfer bodies, particularly intermediate transfer bodies for electrostatic recording and electrophotographic copying.

Conventionally, in recording devices such as electrostatic recording and electrophotography, an electrostatic charge image is formed on an image carrier such as a photoreceptor drum, and this is developed using a developing agent mixed with toner and, if necessary, carrier. and transfer the obtained toner image onto a transfer sheet, for example electrostatically,
Images are formed based on the process of further fixing.

However, when a toner image is electrostatically transferred onto a transfer sheet (recording material) using a transfer electrode such as a corona discharger as in the past, charge disturbance occurs and the resolution of the toner image decreases. Put it away.
Furthermore, when a dielectric magnetic toner or the like that can provide a high-quality toner image is used as the toner, a state in which transfer is virtually impossible is caused.

As a method to improve the above-mentioned drawbacks of electrostatic transfer, attempts have been made to press transfer onto a transfer sheet using a pressure roll, but the transfer efficiency is poor and only about half the amount of toner image is transferred. There is a disability.

Therefore, for example, in Japanese Patent Publication No. 46-41679, Japanese Patent Publication No. 48-22763, Japanese Unexamined Patent Publication No. 49-78559, and US Pat. The image is transferred by pressure, and the transferred toner image is transferred by pressure onto a transfer sheet while being heated and melted using a hot roll.
A method of fixing (transfer fixing) has been proposed. In such a method, a toner image is pressure-transferred onto the surface layer of a rubber-based transfer layer, such as silicone rubber, which has releasability on the one hand and has the property of adhering fine particles when pressed. The toner image is melted by contact with a heating body such as a heat roller, and is transferred under pressure onto a transfer sheet fed at the same time and fixed. In other words, the toner image melted by heating is easily transferred and fixed onto the transfer sheet based on the above-mentioned releasability of the transfer layer, so there is no reduction in the resolution of the toner image due to the transfer process, and moreover, the transfer rate is high. is expected to be realized.

However, since the transfer layer made of silicone rubber described above has a small elastic aftereffect (deformation recovery time from an elastic deformation state), when toner particles are peeled off from the photoreceptor (i.e., pressure transfer), the toner particles are transferred to the surface of the transfer layer. It was found that the holding effect was insufficient and the press transfer rate was not very high.

In view of these circumstances, it is an object of the present invention to particularly improve the pressure transfer rate while taking advantage of the features of the pressure intermediate transfer method as described above.

This object is achieved by using the intermediate transfer body according to the present invention, in which the transfer layer is mainly formed of a mixture of fluorosilicone rubber and non-fluorosilicone rubber (hereinafter simply referred to as silicone rubber). This is accomplished by an intermediate transfer member.

According to the intermediate transfer member of the present invention, the transfer layer is mainly made of a mixture of silicone rubber and fluorosilicone rubber, and fluorosilicone rubber in particular has a larger elastic aftereffect than ordinary silicone rubber, and therefore The elastically deformed state can then be maintained for a sufficient period of time to entrap the toner particles. Therefore, the transfer layer exhibits a high pressure transfer rate due to the action of the fluorosilicone rubber. However, since fluorosilicone rubber has a large negative chargeability (due to the fluorine content) and tends to be positively charged on the side of the toner image carrier, it is inappropriate to form a transfer layer by itself. The transfer layer of the present invention contains silicone rubber which has a negative chargeability as high as that of fluorosilicone rubber and good adhesiveness as described above, so that it can sufficiently eliminate the above-mentioned drawbacks of fluorosilicone rubber and have its advantages. This makes it possible to provide an excellent transfer layer that takes advantage of this.

In order to obtain these remarkable effects, the content ratio of each rubber component in the transfer layer should be fluorosilicone rubber: silicone rubber = 30:70 to 95:
5 is suitable for the above reasons, and more preferably fluorosilicone rubber:silicone rubber=50:50 to 90:10 is suitable for the present invention. If the ratio is outside this range and the amount of fluorosilicone rubber decreases, the above-mentioned elastic aftereffect will be small and the pressure transfer rate will decrease, and if the amount of fluorosilicone rubber is too large, the charging performance of the toner image carrier side will be affected and the photosensitivity will decrease. , developing performance, static elimination properties, etc. are likely to be adversely affected.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows the main parts of a pressure transfer type electrophotographic copying machine incorporating an intermediate transfer member 1 according to the present invention.

In this copying machine, an original 4 covered with a platen cover 3 is placed on the glass surface of an original placing table 2 that is movably provided on the upper wall of the main body. Light 6 from 5 is irradiated through a slit 50 provided on the upper wall of the main body, and the reflected light passes through an SLA (self-cleaning lens array) 7, is reflected by a mirror 8, and then enters a photosensitive drum 9. Therefore, the uniformly charged photosensitive layer 10 made of selenium, organic photoconductive material, etc. of the drum 9 is exposed to a pattern corresponding to the original image by moving the original table 2 in the direction of the arrow. is performed to form an electrostatic latent image. Reference numeral 11 in the figure is a corona charger, which charges the entire surface of the photosensitive layer to a predetermined polarity in an unexposed state. Further, 12 is a device consisting of a light emitting diode array or an electroluminescent plate for preventing black frames, which eliminates the charge on the non-image area on the photoreceptor and prevents toner from adhering to the non-image area. There is a function to do that. A known conductive toner 14 is supplied from a developing sleeve 13 to the photosensitive drum 9 on which the electrostatic latent image is formed. The thickness of this toner 14 is regulated by a magnetic roll 15 for regulating the toner thickness.
It is conveyed on the sleeve 13, but due to the rotation of the sleeve 13 and the magnet roll 16 inside the sleeve 13.
The conveying force is applied by the rotation of . and,
Since a reverse charge is induced in the toner 14 by the electrostatic latent image on the photoreceptor drum 9, the toner particles are sequentially moved and adsorbed onto the photoreceptor drum 9 in proportion to the amount of charge of the electrostatic latent image. A toner image of a predetermined pattern is formed on the toner image, and development is performed.

The toner image thus formed is then pressure-transferred to the intermediate transfer roll 1 which is in contact with the photoreceptor drum 9 at a linear pressure of about 1.0 Kg weight/cm or less (for example, about 0.4 Kg weight/cm). be done. This roll 1
As will be described later, since the surface layer has a surface layer mainly composed of a mixture of silicone rubber and fluorosilicone rubber, the toner particles on the photoreceptor drum 9 can be sufficiently removed. The peeled toner particles are
The next pressure roll 1 is placed on the roll 1 while being preheated to a predetermined temperature (that is, a temperature that exhibits sufficient mold release properties) by the heater lamp 17 inside the roll 1.
It is carried to position 8. The pressure roll 18 is heated to a predetermined temperature by an internal heater lamp 19, and is moved from a paper feed box 20 to a guide plate 22 by a paper feed roll 21.
Copy paper 2 fed via conveyance roller 23
4 is fed between rolls 1 and 18 while being heated. Therefore, the copy paper 24 has a temperature sufficient to transfer the toner image, and when fed between the rolls 1 and 8, the toner image, which has already been preheated, is separated from or transferred from the roll 1, and At the same time, the toner image can be fixed on the copy paper 24. In the figure, 25 is a cleaning roller for the pressure roll 18, 26 is a cleaning roller for the intermediate transfer roll 1, 27 is a guide plate for sending the fixed copy paper to the paper discharge roller 29 on the paper discharge tray 28 side, and 30 Reference numeral 31 designates a roller for feeding copy paper from the bottom of the tray 28 during double-sided copying, and a guide plate 31 during double-sided copying.

At the latter stage of the intermediate transfer roller 1, a transparent filter 33 is connected to the photoreceptor drum 9 from a static elimination lamp 32.
Light is irradiated through the drum to erase any residual charge on the drum. Furthermore, a cleaning member 34 made of, for example, a rubber roller is brought into contact with the photoreceptor drum 9, and the separated residual toner particles are collected on a collecting magnet (both not shown) by a scraping blade. .

What should be noted in the copying machine configured as described above is that the intermediate transfer roll 1 is made of a metal support such as aluminum, stainless steel, or brass, an elastic support, or a resin support, as shown in FIG. It has a structure in which a surface (transfer) layer mainly composed of silicone rubber and fluorosilicone rubber (for example, 50:50) is provided on a support 37 such as a body.

The silicone rubber forming the transfer layer 38 may be a known methyl silicone rubber, methyl phenyl silicone rubber, methyl vinyl sulcone rubber, etc.
KE−40, 41, 42, 42S, KE−441, 44, 45,
45SKE−471, 47, 48, KE−67, 103, 1205,
1206, 1300, 1600, KE−12, 16, 17, 62, 1091,
1093, 1400 (both room temperature vulcanization type), KE−104,
106, 1201, 1202, 1204, KE-1212, 1800 (all low temperature vulcanization type) [all of the above are Shin-Etsu Chemical Co., Ltd.
Co., Ltd.] etc. are available. On the other hand, as for the polymerization type of silicone rubber, an addition polymerization type is more desirable than a condensation polymerization type (for example, the above-mentioned KE-44).
Addition polymerization type silicone rubber has no unreacted components compared to condensation polymerization type rubber, and therefore can maintain the performance of the image carrier (image forming ability) well. It is possible to fully exhibit properties (peelability of toner image) and transfer/fixing properties (transfer of toner image onto recording material = releasability). Such addition-polymerizable silicone rubbers are preferably linear or crosslinked polymers in which a silicone compound having a hydrogen-silicon bond and a silicone compound having a vinyl group are produced in the presence of a platinum catalyst, for example. used for. The general formula of a silicon compound having a vinyl group is: [In the formula, R represents a hydrogen atom, a lower alkyl group, a fluorinated lower alkyl group, an alkoxy group, an aryl group, or a vinyl group, at least one R is a vinyl group, and m and n are oxygen-silicon bond units. represents the number of bonds. ].

Specific examples of compounds included in this general formula include [CH ₂ =CH(CH ₃ ) ₂ Si] ₂ O, [CH ₂ =
Examples include CH(CH ₃ )SiO] ₃ and the like. Further, the general formula of the silicon compound having the above hydrogen-silicon bond is: [wherein R is a hydrogen atom, a lower alkyl group, a fluorinated lower alkyl group, an alkoxy group, or an aryl group, and at least one R is a hydrogen atom,
l represents the number of bonds in the oxygen-silicon bond unit. ].

Specific examples of compounds included in this general formula include, for example, H(CH ₃ ) ₂ SiOSi(CH ₃ ) ₃ , [H
(CH ₃ ) ₂ Si〕 ₂ O, (CH ₃ ) ₃ SiO〔SiH(CH ₃ )O〕Si
(CH ₃ ) ₃ , etc., and such siloxanes that are already commercially available include KF-99 manufactured by Shin-Etsu Chemical Co., Ltd. and SH-1107 manufactured by Toyo Rayon Co., Ltd.
etc. are known.

Further, the other fluorosilicone rubber forming the transfer layer 38 may be made of the above-described silicone rubber into which fluorine atoms have been introduced by substitution. That is, in the above compounds, all CH ₃ groups are replaced with CF ₃ groups,
Those in which some CH ₃ groups are replaced with CF ₃ groups (some CH ₃ groups remain), and CHxF ₃ -x in which the hydrogen atoms of CH ₃ groups are replaced with fluorine atoms.
Examples include those having a group.

Next, a reinforcing filler can be added to the transfer layer 38 of the intermediate transfer body of the present invention for the purpose of increasing its physical strength, increasing its weight, etc. The tensile strength of silicone rubber is generally about 3 to 10 kg/cm ² , and an increase in the tensile strength can be achieved mainly by adding the above-mentioned reinforcing filler. As for the silicone rubber filler, the smaller the particle size and the larger the surface area, the greater the reinforcing effect. These fillers include Valron (Estersil; surface treated silica), Aerosil (high purity fumed silica),
Santocel C.S. (silica airgel) etc. can be used.

The above transfer layer also has improved heat resistance and flame resistance,
Various additives can be added for the purpose of coloring, adjusting resistance value, etc. For example, coloring agents such as pigments and dyes such as carbon black, titanium white, lead white, and zinc white; iron compounds such as iron octylate and iron oxide;
Heat resistance improvers such as titanium oxide, nickel oxide, zirconium silicate, and other rare earth elements such as cerium and lanthanum; flame retardants such as compounds such as copper, nickel, and cobalt, or organic halogen compounds are added to improve the transfer layer. Properties can be improved.

Next, in order to manufacture the above intermediate transfer member 1, a dope is formed by diluting, for example, a silicone rubber and fluorosilicone rubber raw material by adding an organic solvent with a relatively high boiling point. And, as shown in Figure 3,
The dope 40 described above is spray applied while the support drum 37 is being rotated. In this case, a known spray applicator 41 itself can be used,
The dope 40 is drawn into the nozzle 43 by compressed air from the compressor 42, and is ejected from there onto the circumferential surface of the rotating support 37. The nozzle 43 is moved linearly in the axial direction of the support 37, thereby uniformly forming a spray coating layer on the support 37. If the coating layer is heated to about 100 to 200 DEG C. after this coating, the coating layer is cured by heating, and the transfer layer 38 made of the addition polymerizable silicone rubber can be formed to have a uniform thickness.

The transfer layer 38 thus formed by the spray coating method has an appropriate surface roughness (particularly a surface roughness of 0.1 to 5S) due to the spray coating method, and exhibits sufficient adhesion to the toner particles described above. ing. With this spray application,
Although the transfer layer 38 cannot be formed very thick, it can be formed into a relatively thin (particularly 200 μm or less) and uniform film. If the film thickness is less than 5 μm, coating may not be uniform.

FIG. 4 shows a reference example.

The intermediate transfer roll 1 according to this example has a support 37
It has a two-layer transfer layer on which a fluorosilicone rubber layer 39 with a thickness of about 50 to 75 μm and a normal silicone rubber layer 40 with a thickness of about 50 to 100 μm are laminated. Even with this configuration, as described above, the press transfer rate of the toner can be increased, and the adverse effects of the charging property of the rubber can be prevented.

According to this intermediate transfer member, since the rubber layer 40 on the surface side of the transfer layer 38 is mainly formed of silicone rubber, the toner particle releasability characteristic of silicone rubber can be obtained, and at the same time, the rubber layer 40 on the support side of the transfer layer 38 can be obtained. Since the rubber layer 39 is mainly made of fluorosilicone rubber with a large elastic aftereffect, the transfer layer 3
The toner particle retention ability compared to No. 8 is increased, and the transfer rate during pressure transfer can be improved. Moreover, the presence of the rubber layer 40 on the surface side can effectively prevent the negative chargeability of the fluorosilicone rubber of the rubber layer 39 on the support side from having an adverse effect.

In this case, the thickness of each rubber layer is preferably selected appropriately, and the thickness of the rubber layer 39 is desirably about 100 μm or less, and the thickness of the rubber layer 40 is preferably about 30 μm or more. These thickness ranges are determined in such a way that the elastic aftereffects of the fluorosilicone rubber can be exerted while not being affected by its charging properties.

The intermediate transfer member shown in Fig. 4 is inferior to the intermediate transfer member shown in Fig. 2 because there is no fluorosilicone rubber on the surface of the transfer layer, but the structure shown in Fig. 4 is applied to the cleaning member. Good results can be obtained. The cleaning member will be detailed later.

FIG. 5 schematically shows another embodiment using a belt-type intermediate transfer body, which is different from the example in FIG. 1, and parts common to those in FIG. 1 are given common symbols. The explanation is omitted.

In the figure, 51 is an electrostatic latent image forming section including the above-mentioned charger 11 and exposure system, 53 is a developing section including the above-mentioned developing sleeve 13, and 58 is the above-mentioned static elimination lamp 32.
59 is a cleaning section including the above-mentioned cleaning member 34 and the like. The intermediate transfer section includes a transfer belt 7 that runs through a transfer roll 60, a pressure roll 61, and a tension roller 62.
It starts from 1. The transfer belt 71 is made of a base material such as an electroformed nickel belt or a stretch-cast polyimide belt, on which the silicone rubber layer 38 or 39 and 40 as described above is provided. This transfer belt 71
After the toner image is peeled off by being pressed by the photosensitive drum 9, the toner image is preheated by an infrared heater 65 and brought into close contact with the copy paper 24, which is passed between the pressure roller 18 and the toner image. 24
transferred and fixed on top. After this transfer, the belt 71
Paper dust etc. on the top is removed by a cleaning device 64,
Furthermore, the transfer surface of the belt 71 is neutralized by a static eliminating device 66 .

In addition, the above-mentioned rubber layer 38 (or 39 and 4
0) is also effective when applied to the cleaning member 34 shown in FIG. That is, as shown in FIG. 6, when the rubber layer 38 is applied to the cleaning member 34, the rubber layer 38 still remains on the photoreceptor drum 9 because the rubber layer 38 tends to be negatively charged due to the fluorine content. If the residual toner is positively charged, this toner is physically removed or adhesively peeled off by the cleaning member 34 in the same manner as in the above-mentioned pressure transfer, and at the same time, it is also electrostatically attracted. Ru. Therefore, the residual toner is effectively removed onto the cleaning member 34, so that the cleaning action can be significantly enhanced. The arrangement, shape, and structure of the cleaning member 34 are not limited to the example described above.

Although the present invention has been illustrated above, the embodiments described above can be further modified based on the technical idea of the present invention.

For example, other known mechanisms may be used as the intermediate transfer mechanism described above. The toner image on the intermediate transfer body is
The image may be transferred onto a second intermediate transfer body instead of copy paper, and further transferred from this second intermediate transfer body to copy paper. Further, in the above example, the transfer and fixing were performed simultaneously, but the fixing section may be provided separately at another location. Note that the method of the present invention can be applied to recording devices other than electrophotographic copying machines.

[Brief explanation of drawings]

1 to 3, 5 and 6 show embodiments of the present invention, and FIG. 4 shows a reference example, and FIG. 1 shows an electrophotographic copying machine having an intermediate transfer body. 2 is a sectional view of the intermediate transfer body, FIG. 3 is a schematic diagram of the formation of the surface layer (transfer layer) of the intermediate transfer body, and FIG. 4 is a sectional view of another intermediate transfer body. , 5th
The figure is a schematic view of the main parts of an electrophotographic copying machine according to another example. FIG. 6 is a sectional view of a cleaning member. In addition, in the symbols shown in the drawings, 1,71
...Intermediate transfer body, 9...Photosensitive drum, 13...
Developing sleeve, 14... Toner, 17, 19...
Heater lamp, 18, 61...Crimping roll, 2
0... Paper feed box, 22, 27, 31... Guide, 2
4... Copy paper, 28... Receiver, 32... Static elimination lamp, 34... Cleaning member, 37... Support, 38... Transfer layer made of fluorosilicone rubber and silicone rubber, 39... Fluorosilicone rubber Layer, 40...Silicone rubber layer, 40
...addition polymerization type silicone rubber dope, 41...
...Spray applicator, 60...Transfer roll, 62...
...Tension roller, 65... Heater.

Claims (1)

[Claims] 1. In an intermediate transfer body used to transfer a toner image on an image carrier and further transfer this transferred toner image to the next transfer material, the surface of this intermediate transfer body is directly pressed against the image carrier. The transfer layer is mainly formed of a mixture of fluorosilicone rubber and non-fluorosilicone rubber, and the content ratio of the fluorosilicone rubber and the non-fluorosilicone rubber is 30% by weight. :70 to 95:5, the surface roughness of the transfer layer is 0.1 to 5S, and the thickness of the transfer layer is 5 to 200 μm.