JP4774279B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image fixing method using an electrophotographic system such as a copying machine, a printer, a facsimile, and the like, and an image forming apparatus including the apparatus .

Image forming apparatuses used for printers, facsimiles, copying machines, and the like record images including characters, symbols, and the like on recording materials such as paper, cloth, and OHP sheets based on image information.
There are various types of such recording apparatuses. Among them, electrophotographic image forming apparatuses are widely used in offices because they can record high-definition images on plain paper at high speed. In this electrophotographic image forming apparatus, a heat fixing method in which toner on a recording medium is heated and melted and pressurized to fix the toner on the recording medium is the mainstream.
However, about half or more of the power consumption in these image forming apparatuses is consumed for heat fixing type toner heating, and a low power consumption (energy saving) fixing device is desired from the viewpoint of reducing environmental load in recent years. Yes. That is, there is a demand for a fixing method in which the heating temperature at the time of fixing is extremely lower than before or does not require heating.
From the viewpoint of energy saving, it is ideal to fix the toner without heating at all. As this non-heat fixing method, so-called solvent fixing in which a solvent that dissolves a toner resin is applied to unfixed toner is known (for example, see Patent Document 1).

In the solvent fixing, a method has been proposed in which a fixing solution that dissolves or swells toner is applied to the toner to dissolve or swell the toner, and this fixing solution is dried to fix the toner. This fixing method does not require a heat treatment for dissolving the toner as in the case of the thermal fixing method, and can be said to be an excellent fixing method as an energy saving measure with low power consumption.
However, in the above prior art, water, which is a dispersion medium of the softener, does not correspond to VOC (volatile organic compound), and there is no problem. However, for other organic compounds in the softener, odor (unpleasant odor or irritating odor) ) And safety (PRTR law compliant varieties and Proposition 65 varieties) are listed as examples in the examples. When used in an office environment, the material may cause adverse effects on the human body or be uncomfortable. Odor fills the office and its use in the office environment is a problem. In addition, when a large amount of fixing agent is applied to an unfixed toner image, wrinkles and curls occur on the recording medium due to moisture absorption, and the stable and high-speed recording medium (transfer paper) conveyance necessary for the image forming apparatus is significantly impaired. It will be. Further, if this large amount of water is to be removed by evaporation using a drying device, electric power comparable to that of the heat fixing device is required. Further, in order not to impair the fluidity between particles due to the influence of moisture in the atmosphere, the surface of the toner fine particles is treated with water repellency. In the case of a fixer using water as a solvent, When applied, there is a serious problem that the toner fine particles are repelled by the liquid and the image is disturbed.

On the other hand, as another solvent fixing method, the toner is dissolved and a solvent compatible with the silicone oil is mixed with the silicone oil to prevent image distortion due to the softening of the toner (see, for example, Patent Document 2). . That is, the flow of the softened toner is suppressed by the silicone oil having a relatively high viscosity. The solvent disclosed in the present invention is an aromatic solvent such as benzene, or a ketone solvent such as methyl ethyl ketone, which is volatile and has a bad smell, and has a problem from the viewpoint of the VOC problem. Many.
For these inventions, a solution that is harmless to the human body is used as a fixing solution, and the amount of adhesion on the recording medium such as transfer paper is reduced to prevent curling and wrinkling before transferring to the recording medium. There is an example in which a fixing solution is supplied to the toner of the toner to reduce the amount of adhesion on the non-image area (see, for example, Patent Document 3).
There has been proposed a method for increasing the adhesion between the toner and the adhesion between the toner and the recording paper by deforming the toner by pressurizing and heating the toner particles in advance so that the toner does not scatter when the fixing liquid is applied. (For example, refer to Patent Document 4). Therefore, pressurization is almost premised, and the heating means is in contact with the toner layer, which may disturb the image.
In the fixing method using the fixing liquid for softening the toner resin particles on the recording medium, an energy-saving and safe fixing device can be obtained as described above. However, the fixing speed is the same as the penetration speed of the softener into the resin particles and the recording medium. Because it depends, it is difficult to speed up.

JP-A-53-118139 JP 59-119364 A JP 2004-109750 A JP 2004-294847 A

  In a process of fixing a visible image to a recording medium, a fixing device having high-speed compatibility is provided by performing necessary heating with or without contact with toner particles or a recording medium to accelerate penetration of the fixing liquid. .

In the first aspect of the present invention, an image forming unit that forms an unfixed image with colored particles obtained by dispersing a coloring material and a resin to form fine particles, an intermediate transfer member that primarily transfers the formed unfixed image, A transfer means for transferring the transferred unfixed image onto a recording medium, and further, a fixing solution containing a softener having a property of softening the colored particles as a component. a supply means for supplying the recording medium, an image forming apparatus having a fixing device for fixing the colored particles and a pressurizing means for pressurizing the recording medium imparted with the fixing liquid to the recording medium, wherein fixer, wherein the diisobutyl adipate containing 50 [Wt%] colored particles as a softening agent having the property of dissolving or swelling, dimethylsiloxane 50 [Wt%] contains as a component of the diluent, wherein At least one temperature adjusting means for adjusting a temperature suitable for wearing,
The temperature adjusting means fixes the temperature of the fixing solution by adjusting the temperature to 45 ° C. to 50 ° C.

  According to the present invention, in an image forming apparatus having a fixing device that applies a fixing liquid containing a softening agent that softens a resin to colored particles containing a resin, at least one temperature adjusting unit is set so that the temperature is suitable for fixing. Therefore, softening of the resin is promoted, and high-speed fixing is possible.

FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment of the present invention.
In the same figure, an intermediate transfer belt 110 is used as an intermediate transfer member, and reference numerals 1Y, 1M, 1C, and 1B denote image forming portions. It shows only by a code. Reference numeral 1 denotes an image forming unit, 20 denotes a charger, 30 denotes a photosensitive member, 40 denotes a developing device, 41 denotes a developing roller, 42 denotes a cleaning member, 43 denotes a stirring screw, 44 denotes a coating roller, 50 denotes a static elimination lamp, and 60 denotes cleaning. 70, an intermediate transfer unit, 71, 72, 73 are suspension rollers, 74, 75, 76 are tension rollers, 77 is a primary transfer bias roller, 79 is a cleaning member, 80 is a transfer device, 81 is a secondary transfer bias A roller, 85 a separating device, 90 a fixing device, 110 an intermediate transfer belt, and 200 a transfer sheet as a recording medium. A is an arrow indicating the rotation direction, B , C, M, and Y are colors, and indicate black, cyan, magenta, and yellow, respectively.
The basic idea of the present invention is that the fixing process such as deforming the toner and increasing the adhesion between the toner particles and between the toner and the recording medium depends on the action of the fixing liquid when accelerating the penetration of the fixing liquid. Therefore, it is not necessary to carry out the process before applying the fixing solution. For this reason, it is an idea that heating the toner particles, the recording medium, and the fixing liquid supply means can be performed without contact with the image surface.
In FIG. 1, a charger 20, an image forming unit 1 using a light beam from an exposure device (not shown), a developing device 40, a transfer device 80, and a cleaning device 60 are disposed around a photosensitive member 30 as a latent image carrier. . As a material of the photoreceptor 30, a-Si, OPC, or the like can be used. Further, as the charger 20, a form such as a roller or a charger can be used. As the exposure apparatus, an LED, a laser scanning optical system, or the like can be used.

A case where an image is formed by reversal development with the copying machine having the above configuration will be described. The photosensitive member 30 is rotationally driven in the direction of arrow A at a constant speed during copying by a driving means such as a motor (not shown). Then, after being charged uniformly in the dark by the charger 20, the image forming unit 1 irradiates and forms an original light image by exposure, and the electrostatic latent image is carried on the outer peripheral surface of the photoreceptor 30. . Thereafter, the electrostatic latent image is developed while passing through a portion of the developing device 40. The toner image developed into the electrostatic latent image is transferred to the intermediate transfer belt 110 by the transfer unit 77 and then transferred to the transfer paper 200. After the transfer, the residual potential of the photosensitive member 30 is removed by the static elimination lamp 50, and the residual toner is removed by the cleaning device 20 to prepare for the next image formation.
The transferred transfer paper 200 is conveyed to the fixing device 90. First, an electric field for pressing toner particles against a recording medium is formed by an electric field applying unit (not shown), and then a fixing solution containing a component that dissolves the resin particles of the toner is supplied by a supplying unit (not shown). Is dissolved and swollen and fixed. At this time, since the bonding property between the recording medium and the toner particles is enhanced by the electric field applying means in advance, the flow of the toner particles due to the application of the fixing liquid can be prevented, and the disturbance of the image can be prevented.

The developer used in the copying machine of this embodiment has a low viscosity (about 1 mPa · s) and a low concentration (about 1%) using Isopar (trademark of Exxon), which is generally commercially available and used conventionally. It is not a liquid developer but a liquid developer with high viscosity and high concentration. As the viscosity and concentration range of the developer, for example, a viscosity of 50 to 10,000 mPa · s and a concentration of 5% to 40% are used. As the carrier liquid, a highly insulating material such as silicone oil, normal paraffin, Isopar M (Exxon trademark), vegetable oil, mineral oil or the like is used. Volatile and non-volatile can be selected according to the purpose, and the particle size of the toner can be selected according to the purpose from submicron to about 6 μm.
Next, the developing device of this embodiment will be described.

FIG. 2 is a diagram for explaining an embodiment of the present invention.
In the figure, reference numeral 45 is an intermediate roller, 46 is a cleaning member, 47 is a sweep roller, 48 is a cleaning member, 91 is a fixing roller, 92 is a pressure roller, 93 is a fixing liquid, 94 is a fixing liquid storage tank, and 95 is a heater. , 96 are liquid temperature sensors as liquid temperature detecting means, 97 is an electric field applying means, and 98 is a ground wire. The members of the same role as Figure 1 given the same numerals numerals omitting alphabetic code.
This figure shows the relationship between a fixing device and an image forming station of a roller transfer type using a rotating roller instead of the intermediate transfer belt type in FIG.
As shown in FIG. 2, the developing device 40 includes a developer storage tank 40 ′ for storing a developer therein, a developing roller 41, a sweep roller 47, and a coating roller whose surface is engraved with a uniform pattern. 44, an intermediate roller 45, and a stirring screw 43. The developing roller 41, the intermediate roller 45, and the sweep roller 47 are provided with cleaning members 42, 46, and 48 made of metal blades or rubber blades, respectively. Each cleaning member is not limited to a blade, and may be a roller type.

The developing roller 41 and the sweep roller 47 are each provided with an elastic layer having conductivity on the outer peripheral surface. Urethane rubber can be used as the material for these elastic layers. The surface hardness of the elastic layer is preferably 50 degrees or less in terms of JIS-A hardness so that a nip can be efficiently formed with the photoreceptor. The material of the elastic layer is not limited to urethane rubber, but may be any material that has conductivity and does not swell or dissolve with the carrier liquid / developer. Further, the surfaces of the developing roller 41 and the sweep roller 47 are conductive and are made of a material that does not swell or dissolve with the carrier liquid / developer, so that the carrier liquid / developer does not contact the inner layer. If so, the material of the elastic layer as the inner layer may have elasticity without any restriction on the conductivity and swelling and dissolution. At this time, it is necessary to apply the developing bias voltage / sweep bias voltage not from the shafts of the developing roller 41 / sweep roller 47 but from the surface.
Further, the elastic layer may be provided on the photosensitive member 30 side instead of the developing roller 41 and the sweep roller 47. Further, the photoconductor 30 may be composed of an endless belt-like member. Further, the developing roller 41 and the sweep roller 47 are configured by coating or tubes so that the surfaces thereof have smoothness of Rz 5 μm or less.

  When the developing roller 41 and the sweep roller 47 are brought into contact with the photosensitive member with an appropriate pressure, the elastic layer of each roller is elastically deformed to form a developing nip and a removal nip. In particular, by forming the development nip, it is possible to secure a certain development time for the toner of the developer to move and adhere to the photoreceptor due to the development electric field in the development area. Moreover, the nip width which is the width | variety of the surface moving direction in each nip part can be adjusted by adjusting a contact pressure. Each nip width is set to be equal to or greater than the product of the linear speed of each roller and the development time constant. Here, the development time constant is the time required until the development amount is saturated, and is obtained by dividing the necessary minimum nip width by the process speed. For example, if the required minimum nip width is 5 mm and the process speed is 500 mm / sec, the development time constant is 10 msec.

During the developing operation, a thin layer of developer is formed on the developing roller 41 by the application roller 44 via the intermediate roller 45. At this time, the thickness of the developer applied on the developing roller 41 was set so that the pigment content in the toner carried per 1 cm ^{2 of the} surface thereof was 3 μg or more and 60 μg or less. For this purpose, a thin layer of developer was applied to a thickness of 3 to 12 μm. This is because when the developer coating thickness is such that the pigment content in the toner carried per 1 cm ^{2 of the} developing roller surface is less than 3 μg, a sufficient amount of pigment is formed on the photoreceptor. This is because there is a possibility that the image density of the image portion will become thin without moving to the image portion of the latent image. Further, if the pigment content in the toner carried per 1 cm ^{2 on the} surface of the developing roller is greater than 60 μg, the excess toner remaining on the background after development increases and the removal by the sweep roller 47 is not possible. This is because there is a risk of becoming perfect.

  The developer thin layer formed on the surface of the developing roller 41 is developed in accordance with the latent image on the photosensitive member 30 when passing through the developing nip formed by the photosensitive member 30 and the developing roller 41. That is, in the image portion, the toner moves to the photoreceptor 30, and in the background portion (non-image portion), the toner is moved to the surface of the developing roller 41 by the electric field formed by the developing bias potential and the photoreceptor potential. Prevent toner from adhering to the area. However, if a part of the toner on the background portion does not move to the surface of the developing roller 41 and remains on the photosensitive member 30, it causes fogging. Accordingly, the developing device of the copying machine according to the present embodiment is provided with a sweep roller 47 for sweeping (cleaning) toner that causes the fog (hereinafter referred to as “fogging toner”). The sweep roller 47 is disposed downstream of the developing roller 41 in the rotation direction of the photoconductor 30 and is pressed against the photoconductor 30 so as to sandwich the developed toner layer. The surface of the sweep roller 47 removes fog toner from the background while moving at substantially the same speed as the surface of the photoreceptor 30.

  The toner after development on the developing roller 41 is removed by the cleaning member 42 to prevent ghosting, and the liquid developer removed by the sweep roller 47 is removed by the cleaning member 48 to maintain the performance of the sweep roller 47. These liquid developers are collected in an adjustment tank 40 ″, where they are sent again into the development tank 40 ′ after the concentration is adjusted. In the adjustment tank 40 ″, stirring means, and There are density detection means and liquid quantity detection means (not shown), and the density and liquid quantity are detected in a state where the density in the tank is uniform, and density adjustment is performed by replenishment with a new liquid developer or carrier. The supply amount of the liquid developer into the developing tank 40 ′ from here is set to be slightly larger than the usage amount of the liquid developer, and the overflow amount returns to the adjustment tank 40 ″. The liquid developer always circulates.

  Next, the fixing process using the fixing liquid, which is a characteristic part of the present invention, will be described. The fixing device 90 is composed of a pressure roller 92 that sandwiches and opposes the recording medium 200 with a fixing roller 91 that is a supply unit of the fixing liquid 93. A part of the fixing roller 91 is immersed in the fixing liquid 93, and then the amount of the fixing liquid 93 necessary for fixing is held on the fixing roller 91 by scraping off excess liquid with a metaling blade backed by a metal plate. Has been. In contrast, the pressure roller 92 is in contact with the recording medium 200 on which an unfixed image is placed. Since the fixing liquid 93 is supplied between the pressurized nips, the softened resin is crushed and the surface is smoothed, and the image quality after fixing is improved. The heater 95 will be described later.

FIG. 3 is a diagram showing a fixing process of the toner resin on the recording medium. 4A shows the state of the toner resin before fixing, FIG. 2B shows the state during fixing, and FIG. 3C shows the state of the toner resin after fixing.
In the figure, reference numeral ta denotes unfixed toner, and tb denotes fixed toner.
In FIG. 4B, when a fixing agent is applied to the resin of the unfixed toner ta, the resin is dissolved and swollen in the fixing agent to become sticky. It shows a state tb that is discharged from the liquid, penetrates into the recording medium, and the resins are bonded to each other and fixed.
When an excessive amount of the softening agent is supplied, the binding after the softening hardly occurs, and the adhesiveness is maintained even after a long time after the fixing solution is supplied. Here, it is considered that the binding process is caused by the fixing solution softening the resin diffusing inside the resin or penetrating into the recording medium. The speed of diffusion / penetration is important for high-speed compatibility. .

By the way, it is preferable that the pressure at the nip portion to which the fixing liquid is supplied be a pressure that can deform the softened resin. For example, a pressure of about several tens to several hundred kPa may be present. At this time, since the influence of the surface of the fixing roller can be considered, it is preferable that the surface is smooth. For example, the ten-point average roughness Rz as the surface roughness is desirably 2 to 3 μm or less.
In the fixing liquid coating apparatus used in the present invention, an electric field applying unit 97 is provided in the supply unit that supplies the fixing liquid 43, and when the electric field is supplied, toner particles having positive or negative polarity are pushed toward the recording medium 200 side. An electric field that is applied is generated. This electric field can prevent an offset in which the toner is transferred to the fixing roller 41 in reverse. The offset state changes depending on the applied voltage, and the fixing liquid coating apparatus used in the present invention was able to prevent the offset by applying a voltage of 600 V or more to form an electric field.

  The present invention is a so-called new solvent fixing method using a fixing solution containing a softening agent. In the prior art, in addition to odor problems, safety problems, etc., high-speed followability is regarded as a problem, and high-speed copying is considered. It was thought that there might be a limit. However, as described above, it is possible to increase the speed by applying a thin layer of the softening liquid by the application roller method, and further, the fixing speed is further improved by heating and heating the fixing liquid. Of course, the problems such as the safety of the softening solution, the problem of odor, and the toner offset to the roller of the application roller type have been cleared.

By the way, the reason why high-speed followability can be achieved by heating and heating the fixing solution is that the fixing solution containing the softening solution supplied to the toner layer is a fixing solution in which the resin is softened in the binding process as described above. It is considered that the toner on the surface layer is hardened by diffusing into the resin or penetrating into the recording medium, and this diffusion / penetration speed is controlled by heating / heating the fixing liquid, thereby diffusing into the toner resin. It is thought that this is due to further progress.
To reiterate, as a means of improving the permeability of the liquid in order to increase the diffusion / penetration speed of the fixing liquid into the toner layer and the recording medium,
・ Reduces fixer viscosity.
-Improve the affinity of the carrier liquid contained in the toner layer.
There is a method.
To achieve these, the fixing solution is heated and heated.
The recording medium itself is heated and heated.
There is a method. In the latter case, there are two cases where the toner layer is not carried on the recording medium, that is, when heating / heating is performed before transfer and when heating / heating is performed after transfer.
Next, the components of the fixing solution will be described.

1. Softener The softener used in the exemplary embodiment is a material (hereinafter referred to as “softener”) that dissolves or swells the resin component constituting the toner. The softener is preferably a material that does not volatilize, that is, has no odor and does not have an affinity for water. Specific examples of the dissolving / swelling component include saturated aliphatic ester, aliphatic dicarboxylic acid ester, and aliphatic dicarboxylic acid dialkoxyalkyl.

The saturated aliphatic ester is a compound represented by the general formula “R ₁ COOR ₂ ”, R ₁ is an alkyl group having 11 to 14 carbon atoms, and R ₂ has 1 to 3 carbon atoms. It is an alkyl group. Examples of the aliphatic monocarboxylic acid ester include ethyl laurate, ethyl tridecylate, isopropyl tridecylate, ethyl myristate, and isopropyl myristate. These are hardly volatilized and are dissolved in synthetic oils such as silicone oil and PAO, mineral oils, and hydrocarbon solvents, and the solubility in water is 0.1 g / 100 ml (25 ° C.) or less, which is hardly soluble. is there.

The aliphatic dicarboxylic acid ester is a compound represented by the general formula “R ₃ (COOR ₄ ) ₂ ”, R ₃ is an alkylene group having 3 to 8 carbon atoms, and R ₄ has 2 carbon atoms. These are alkyl groups of 5 or less. Examples of the aliphatic dicarboxylic acid ester include diisobutyl adipate, diisopropyl adipate, diethyl sebacate, dibutyl sebacate and the like. Most of these parts are hardly volatilized and are dissolved in synthetic oils such as silicone oil and PAO, mineral oils, and hydrocarbon solvents, and the solubility in water is 0.1 g / 100 ml (25 ° C) or less. It is poorly soluble.

Aliphatic dicarboxylate dialkoxyalkyl is a compound represented by the general formula “R ₅ (COOR ₆ —O—R ₇ ) ₂ ”, R ₅ is an alkylene group having 2 to 8 carbon atoms, R ₆ is an alkylene group having 2 to 4 carbon atoms, and R ₇ is an alkyl group having 1 to 4 carbon atoms. Examples of the aliphatic dicarboxylic acid dialkoxyalkyl include diethoxyethyl succinate, dibutoxyethyl succinate, diethoxyethyl adipate, dibutoxyethyl adipate, diethoxyethyl sebacate and the like. Many of these parts hardly volatilize. The solubility in water is 0.1 g / 100 ml (25 ° C.) or less and is hardly soluble. In addition, since many of these parts have low solubility in synthetic oils such as silicone oil and PAO (poly-α-olefin), mineral oils, and hydrocarbon solvents, the surface activity is about 1 to 5 in HLB value. There is also a method of emulsifying and dispersing in a synthetic oil such as silicone oil or PAO, mineral oil, or a hydrocarbon solvent with an agent.
In any case, the greater the number of carbons, the higher the viscosity and the higher the non-volatility. Also, purification can reduce odor, and some highly purified esters are almost odorless.

-About the point that a softening agent is liquid The example of a liquid softening agent is as above-mentioned. When the softening agent is a liquid, the penetration into the toner layer is faster than in the case of a solid or gel. Even in liquids, the permeation rate depends on viscosity, surface energy, and the like, and those with lower viscosity have a faster permeation rate. In addition, if it is liquid, it can be supplied using a pipe, a pump, or the like, and it is easy to handle because it does not scatter like powder, so the supply method is easy.
Moreover, since it is easy to form a thin layer, there are also advantages such as being easy to regulate the supply amount and being more easily mixed with resin particles than powder.

2. Softener diluting solution If the dissolving / swelling component is supplied in an amount larger than the required amount to the resin to be fixed, the resin will be dissolved too much, causing a flow of the resin to be fixed. The resin to be fixed is desirably in a semi-dissolved state or a swollen state, and depending on the type of the dissolved / swelled component, approximately half or less of the resin is sufficient. Further, a dissolving / swelling component that does not melt and swell unless it is more than that is not suitable because it is difficult to treat the dissolving / swelling component after the resin is melt-swelled. For example, the amount of toner constituting the toner image on the transfer paper is several μm in thickness, and it is desirable to supply the dissolved / swelled component in a thinner and smaller amount. Although it is desirable to be able to supply such a thin and small amount, it is extremely difficult to supply it uniformly. Therefore, as a method for supplying such a small amount of the dissolving / swelling component, a method of diluting the dissolving / swelling component with some liquid is generally used.

-About the volatility of the diluted solution As this diluted solution, the one using water is known in consideration of the influence on the environment. However, when a dispersion or dilution liquid that has good affinity with water or is mixed with water and is easily soluble in water is used, water tends to volatilize and may absorb more water. There is a problem that the density of the fixing agent which is easily changed. Moreover, since the problem of preservability, such as decay, also arises, it is necessary to study preservatives. Further, when the toner is applied on a photosensitive member, an intermediate transfer member or a film-like recording medium, the surface energy may not be applied uniformly. In addition, when transfer paper is used, there is a concern that the paper will cockle (wrinkle). Volatilization also causes odor and air pollution problems.

・ Non-volatile diluent To overcome these problems, it is desirable to use a dispersion / diluent that is non-volatile, hardly soluble in water and has almost no odor. Examples include silicone oil or mineral oil. Etc. Both have various structures and grades (viscosity / molecular weight). In the present embodiment, a solution obtained by mixing 50% of the softening agent and 50% or less of silicone oil 50% as a diluent is mainly used as a fixing agent.
If the softening agent is a liquid, it can be used as a fixing solution with only the softening agent. However, the amount of resin on the recording medium is extremely small, and it is difficult to supply an amount that does not become excessive. Accordingly, by diluting with an appropriate diluent and supplying it as a fixing solution, a necessary amount of a softening agent is contained in a supply amount of the fixing solution that can be stably supplied.

3. FIG. 4 is a diagram for explaining the fixing time and smear fixing temperature dependency.
In the figure, reference numerals G ₃₀ , G ₄₀ , and G ₅₀ are curves indicating smear changes at the liquid temperatures of 30 ° C., 40 ° C., and 50 ° C. during fixing, respectively. The horizontal axis represents the elapsed time (unit: minutes) from the fixing solution application, and the vertical axis represents the smear value described later.
The fixing time is a time from when the fixing solution is supplied until a satisfactory fixing property is obtained. Satisfactory fixing property means a state where the smear value is 0.2 or less (broken line in the figure).
The present invention is a solvent fixing method in which a fixing liquid containing a softening agent is supplied to an unfixed image (toner) on a recording medium, and the toner image is softened, partially dissolved, and fixed on a recording medium (transfer paper). The fixing speed depends on the penetration speed of the fixing liquid into the resin particles and the recording medium, and the time required for softening the resin. In order to shorten the fixing time, it is important to accelerate the penetration of the fixing solution into the toner layer. The viscosity of the fixing solution has a great influence, and the lower the viscosity, the faster the penetration. Further, the time required for softening the resin varies depending on the temperature, and the shorter the time, the higher the temperature.

The smear value mentioned here is a value obtained by the following inspection procedure.
At the tip of the clock meter, an elastic material with a thickness of 5 mm is attached as a cushion material, and a cloth is placed on the elastic material.
The density (three-point average) on the cloth after rubbing 10 times on the solid image is measured (Dcrk), and the value obtained by subtracting the cloth density (Dcls) from that is divided by the original image density (Dinit). Is the evaluation value in the smear method. That is, Dsmr is defined by the following equation.
Dsmr = (Dcrk−Dcls) / Dinit
The smaller the value of Dsmr, the better the fixability, and the current target value is 0.2 or less.

FIG. 5 is a diagram for explaining a reference configuration example 1 of the present invention.
The first reference configuration example is a configuration in which the toner temperature is increased immediately after the primary transfer.
Increasing the resin temperature is thought to soften the resin, accelerate the penetration of the fixer, and accelerate the softening of the resin by the fixer. In the image forming apparatus using the intermediate transfer body 100, in addition to the heater 95 for raising the liquid temperature, means for heating the toner particles (resin) transferred onto the intermediate transfer body 100, for example, an infrared heater 95 ′ Etc. The infrared heater 95 ′ softens the toner particles. When the toner particles are transferred to the transfer paper 200 and the fixing solution 93 is supplied, the toner particles are further softened by the fixing solution 93 and the fixing time is shortened. The toner particles softened by the heater are softened faster by the fixing liquid than the toner particles not softened by the heater. If the effect is sufficient with only the infrared heater 95 ′, the liquid temperature heater 95 can be omitted.
At this time, a higher amount of heat applied to the resin is more advantageous. Fixing time can be shortened. In particular, if the glass transition point is exceeded, a dramatic effect can be obtained. However, since this heating is not for melting and fixing the toner only by heating as in the conventional heat fixing method, the amount of heat as in the heat fixing method is not required. In particular, it does not have to be above the melting point. This heating softens the resin and accelerates the penetration of the fixing solution, keeps the fixing temperature in an advantageous state for softening the resin by the fixing solution, does not lower the fixing solution temperature when the fixing solution temperature is high, etc. effective.

The heater 95 shown in FIG. 2 is arranged for the purpose of heating the fixing liquid 93 as means for reducing the fixing liquid viscosity in order to shorten the fixing time.
In order to adjust the fixing liquid temperature, the liquid temperature detecting means 96 is provided in the fixing liquid container, the liquid temperature is detected, and the heater 95 is turned ON / OFF based on them. This method can also be used for the purpose of constantly controlling the temperature of the fixing solution in order to provide a constant fixing quality by heating the fixing solution even when used in a cold region.
When the relationship between the liquid temperature and the fixability (smear) was observed in the present invention, excellent fixability could be obtained in a shorter time at 50 ° C. than at the liquid temperature of 30 ° C.
The major merit of solvent fixing is non-heating. The heating of the fixer is controlled to 1/2 to 1/3 (200 to 300 W or less), and the specific temperature is 100 ° C. or less, preferably about 50 ° C. as the upper limit with respect to the power used conventionally. To control the heat source (heater).

FIG. 6 is a diagram for explaining a reference configuration example 2 of the present invention.
If the fixing solution 93 is merely heated, if the heat capacity of the supply means is large, the temperature of the fixing solution is lowered, so that a sufficient effect cannot be obtained and fixing time is required. Therefore, the fixing solution supply means is also provided with a heating means 95 " so that a sufficient effect can be obtained by setting the temperature equal to that of the fixing solution 93. In the figure, as a fixing solution supply means, a fixing roller 91 having a built-in heater. An example using is shown.
When the heat capacity of the supply unit is sufficiently larger than the heat capacity of the fixing solution, the temperature of the fixing solution can be controlled only by controlling the temperature of the supply unit.
Although not shown, a heater may be incorporated in the pressure roller 92 to form a heat roller.

FIG. 7 is a diagram for explaining a reference configuration example 3 of the present invention.
In the figure, reference numeral 101 denotes a conveyance belt for a recording medium.
FIG. 8 is a diagram for explaining a reference configuration example 4 of the present invention.
Even if the fixing solution 93 and the fixing solution supply unit 91 are warmed, if the recording medium 200 having a low temperature enters, the fixing solution temperature and the color resin temperature may be lowered, and a sufficient effect may not be obtained. Therefore, a better effect can be obtained by heating the recording medium.
Considering shortening of the fixing time, it is conceivable that the penetration of the fixing solution into the toner layer is accelerated, the viscosity of the colored resin is decreased, and the melting property is increased. The effect of heating and heating the fixing solution as a means for reducing the viscosity of the fixing solution is as described above. On the other hand, the same effect can be brought about by heating the recording medium (transfer paper). Furthermore, heating the recording medium has the effect of heating the colored particles on the recording medium, and the fixing time can be shortened. The embodiment shown in both figures is an example in which the transfer paper is heated before transfer, and is in contact (FIG. 7), non-contact (FIG. 8), from the image plane (FIGS. 7 and 8), and from the back (FIG. 8) Various heating means can be installed.
In the reference configuration examples 3 and 4 in FIGS. 7 and 8, the heating means (heater 95 or infrared heater 95 ′) of the fixing device 90 may be added as necessary. Is not specified. The same applies to the following drawings. However, if the heaters are combined well, it is possible to obtain a high fixing effect by reducing the total energy used.

FIG. 9 is a diagram for explaining a reference configuration example 5 of the present invention. FIG. 4A is a configuration diagram, and FIG. 4B is an enlarged view of a pressure roller.
In the figure, reference numeral 102 denotes an emery roller as a pressure roller.
Although it is effective to heat the transfer paper before applying the fixing liquid, in order to enhance the effect, it is preferable to heat the recording medium 200 on which the colored particles (toner particles) are placed. To heat the toner particles and the recording medium 200 without directly touching the unfixed toner, a heat roller 95 ″ having a heater built in the roller is brought into contact with the surface opposite to the toner image surface. The emery roller 102 is in contact with the image surface so that the image is not slid, and the emery roller locally presses the image surface with a point contact so that it does not touch the image as much as possible. In addition, the recording medium 200 is pressed against the heating roller so as not to disturb the image even when touched.

FIG. 10 is a diagram for explaining a reference configuration example 6 of the present invention.
When the transfer paper 200 and the toner layer were heated after applying the fixing solution 93 to the toner image, excellent short-time fixing could be obtained. Even if the fixing solution 93 and the fixing solution supply means 91 are warmed, the temperature of the transfer paper 200 decreases depending on the environment after the fixing solution is supplied, and the acceleration effect in the infiltration process of the fixing solution 93 into the transfer paper 200 is particularly low. It may become. Therefore, by heating the recording medium 200 after supplying the fixing liquid, the high temperature state can be maintained for a long time. In addition to heating the colored resin, the fixing liquid 93, the fixing liquid supplying means 91, the recording medium 200, etc., Fixing can be made faster.
Heating after applying the fixing solution includes a non-contact type heater such as infrared rays or a method in which the opposite surface without the toner image is brought into contact with the transfer paper with a heater built-in roller.

  The recording medium is specifically transfer paper, and there are many types. According to our study, the nature of the transfer paper affects the fixing quality (short-time fixing). When the thickness is large, the heat capacity is large, so that at the same fixing solution temperature or fixing solution supply means temperature, the fixing solution temperature at the time of applying the fixing solution is lowered and the fixing speed is slowed down. Therefore, by increasing the fixing solution temperature or the fixing solution supply means temperature in accordance with the thickness, the fixing solution can penetrate the transfer paper quickly so that the speed can be reduced. When the smoothness is low, heat transfer is poor, and therefore the resin temperature cannot be increased unless the temperature is increased. Therefore, by adjusting the fixing solution temperature or the fixing solution supply means temperature according to the smoothness, the fixing property equivalent to that of the paper with high smoothness can be obtained. Further, in the case of a coated paper, in the case of a coat layer in which the liquid is difficult to penetrate, the penetration is hindered. As described above, the permeation diffusion speed of the fixing solution varies depending on the physical properties (thickness, smoothness, etc.) of the transfer paper. Therefore, by changing the fixing solution temperature or the fixing solution supply means temperature according to the paper physical properties, the fixing speed does not change depending on the paper, and the fixing can be performed efficiently.

Examples of the fixing solution used in the present invention are shown below.
・ Diisobutyl adipate (softener, LD50 = 12.3 g / kg) 50 wt%
・ Dimethylsiloxane (50 mPa · s, diluent, LD50 = 15 g / kg) 50 wt%
In the copying apparatus shown in FIG. 1, an unfixed image formed on a transfer paper of Thunderbird Dalart (trade name) 127 g / m ² is used, and the fixing liquid adhesion amount on the paper is 80 to 80 at a fixing liquid temperature of 30 ° C. When the smear value was measured at 110 mg / A4, the smear value 30 seconds after application was 0.38, and the evaluation result within 1 minute after application was 0.18. Then, when the smear value was measured at a fixing solution temperature of 50 ° C. at a fixing solution adhesion amount of 80 to 110 mg / A4 on the paper, the smear value after 30 seconds after coating was 0.14, and within 1 minute after coating. As a result, it was possible to obtain an excellent fixability of 0.09. FIG. 4 is a plot of the evaluation results.
Assuming that the smear value in one minute after application is allowed to be 0.2, all the conditions are satisfied at 30 ° C. or higher. If the fixability is determined as a smear value of 0.2 or less at 30 seconds after coating, satisfactory fixability can be obtained if it is about 45 ° C. or more interpolated from the graph.

1 is a schematic configuration diagram of a copying machine according to an embodiment of the present invention. It is a figure for demonstrating embodiment of this invention. FIG. 4 is a diagram illustrating a fixing process of toner resin on a recording medium. It is a figure for demonstrating the fixing temperature dependency of fixing time and smear. It is a figure for demonstrating the reference structural example 1 of this invention. It is a figure for demonstrating the reference structural example 2 of this invention. It is a figure for demonstrating the reference structural example 3 of this invention. It is a figure for demonstrating the reference structural example 4 of this invention. It is a figure for demonstrating the reference structural example 5 of this invention. It is a figure for demonstrating the reference structural example 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 30 Photoconductor 40 Developing device 80 Transfer device 90 Fixing device 91 Fixing roller 92 Pressure roller 93 Fixing liquid 200 Transfer paper

Claims (1)

Image forming means for forming an unfixed image with colored particles obtained by dispersing colorant and resin into fine particles, an intermediate transfer body for primary transfer of the formed unfixed image, and the transferred unfixed image as a recording medium A transfer means for transferring the image on the recording medium, and a supply means for supplying a fixing liquid containing as a component a softener having a property of softening the colored particles to a recording medium carrying the unfixed image; An image forming apparatus comprising: a fixing device that pressurizes the recording medium to which the fixing liquid is applied; and fixing the colored particles to the recording medium.
The fixing solution contains 50 [Wt%] diisobutyl adipate as a softening agent having a property of dissolving or swelling the colored particles, and 50 [Wt%] of dimethylsiloxane as a component of the diluent. Having at least one temperature adjusting means for adjusting to a suitable temperature;
An image forming apparatus characterized in that the temperature adjusting means fixes the temperature of the fixing solution at 45 ° C. to 50 ° C.

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