JP2008033179A - Fixing method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve temporal changes and durability of a roller means of applying a fixing solution and applying pressure. <P>SOLUTION: An image forming apparatus comprises a latent image carrier, a developing means of developing an electrostatic latent image on the latent image carrier with toner, a transfer means of transferring the developed toner image onto a recording material, and a fixing means of fixing the toner image on the recording material by applying the fixing solution for softening or swelling toner to the toner image transferred onto the recording material, wherein at least a surface of a member which comes into contact with a fixing-solution applied surface of the recording material after the fixing solution is applied is made of ultrahigh molecular weight polyethylene. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing method and an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more specifically, a fixing method for fixing a toner on a recording medium by applying a fixing liquid that softens or swells the toner to the toner, and image formation Relates to the device.

  Conventionally, thermal fixing type image forming apparatuses that fix toner on a recording material by heating and pressurizing the toner on the recording material have been known, but various fixing methods that do not employ the thermal fixing method have been proposed. As one of them, there is a wet fixing method in which a fixing process is performed using a fixing solution that softens or swells toner. This wet fixing method fixes a toner on a recording material by applying a fixing solution to the toner to soften or swell the toner. This wet fixing method is an excellent fixing method as an energy saving measure because the heat treatment that consumes a large amount of power as in the heat fixing method is not required. In addition, since a warm-up time as in the heat fixing method is not required, a quick start is possible. Examples of an image forming apparatus that employs such a fixing method include those described in Patent Document 1 and Patent Document 2.

In an image forming apparatus using the above-described wet fixing method, it is important to apply a uniform coating amount when applying a fixing solution that softens or swells toner. One method is a roller coating method.
As an example, a fixing device composed of a fixing roller and a supply roller that reverses the fixing roller stabilizes the state of the coating liquid by reverse rotation, and unevenness of ribs and the like is prevented.
Conventionally, a silicone rubber roller has been coated with a PFA tube because a coating nip is ensured, surface smoothness is ensured, a medium resistance of 10 ⁹ to 10 ¹² Ωcm, and it is necessary to apply a bias. The bias was applied from the blade.

  The coating of the PFA tube has a resistance value when bias is applied and solvent resistance of the surface, toner adhesion reduction due to the polymer, sliding noise with the cleaning blade due to the low friction coefficient μ of the surface, etc. The benefits are great.

As will be described later, the present invention mainly uses ultrahigh molecular weight polyethylene as a material for a fixing liquid application roller or the like, but even if the sheet conveyance path of this type of image forming apparatus is a narrow conveyance path. A rotation guide provided so as not to cause defects such as rubbing traces is made of an ultrahigh molecular weight polyethylene sheet-like resin material (see Patent Document 3).
JP 2004-294847 A JP 2004-109749 A JP 2001-10755 A

However, in a fixing device composed of a fixing roller and a reverse supply roller, the coating of the PFA tube is weakly bonded to the base rubber, and there are problems in terms of durability and increasing the amount of pressure and bias application. It was.
Further, in the above-described prior art, by covering the PFA tube, it is easy to cause wrinkles due to the necessity of forming a nip by blade pressure and pressurization.
Further, because of the necessity of forming a nip, the roller is a rubber roller having a low hardness and is coated with a PFA tube. For this reason, the softening liquid that has entered the thickness portion other than the covering portion, the gap between the covering portions, and the like easily dissolves the rubber of the rubber roller. Since the softening liquid has high solubility of the colored resin particles, the rubber material is almost dissolved due to its function. This problem also applies to the pressurizing unit that pressurizes the recording medium after the fixing device with a roller pair. The purpose of the pressing means is to accelerate the fixing property.
However, since the softening agent is applied in the fixing unit, the softening is progressing. Further, the viscosity is higher than that of the fixing roller, and the conditions are such that adhesion is easy. Further, the toner that has passed the time is hardened, and the processing of the collected toner becomes a problem in blade cleaning. Further, when the machine is stopped for a long time, the blade and the roller are fixed through the toner. Furthermore, it is necessary to avoid that the blade pressure is constantly applied.

  In addition, the technique described in Patent Document 3 described above has insufficient durability.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to improve the temporal change and durability of roller means for applying and pressing a fixing solution.

The above problems are solved by the following inventions (1) to (8) (hereinafter referred to as the present inventions 1 to 8).
(1) a latent image carrier, developing means for developing the electrostatic latent image on the latent image carrier with toner, transfer means for transferring the developed toner image onto the recording material, and on the recording material An image forming apparatus comprising: a fixing unit that applies a fixing solution that softens or swells toner to a transferred toner image and fixes the toner image on the recording material. An image forming apparatus characterized in that at least the surface of a member in contact with the fixing liquid application surface is made of ultra high molecular weight polyethylene.
The electrostatic latent image on the latent image carrier is developed with toner, the developed toner image is transferred onto a recording material, and a fixing solution for softening or swelling the toner is applied to the toner image transferred onto the recording material. A fixing method for fixing a toner image on the recording material,
A fixing method comprising: forming at least a surface of a member in contact with a fixing liquid application surface of the recording material from ultra high molecular weight polyethylene, and contacting the fixing liquid application surface of the recording material after application of the fixing liquid.

(2) The fixing unit includes a fixing liquid application roller and an opposing roller facing the fixing liquid application roller, and a member that contacts the fixing liquid application surface of the recording material after the fixing liquid application is the fixing liquid application roller. The image forming apparatus as described in (1) above, wherein
Using fixing means comprising a fixing liquid application roller and an opposing roller facing the fixing liquid application roller, and using the fixing liquid application roller as a member that comes into contact with the fixing liquid application surface of the recording material after application of the fixing liquid. The fixing method of (1) above, which is characterized.

(3) The image forming apparatus according to (2), wherein at least the surface of the facing roller is made of ultra high molecular weight polyethylene.
Using fixing means comprising a fixing liquid application roller and an opposing roller facing the fixing liquid application roller, and using the fixing liquid application roller as a member that comes into contact with the fixing liquid application surface of the recording material after application of the fixing liquid. The fixing method of (1) above, which is characterized.

(4) A pressing roller that presses the toner image on the recording material and a back roller provided opposite to the pressing roller in the traveling direction of the recording material and downstream of the fixing unit. The image forming apparatus according to any one of (1) to (3), wherein a pressure unit is provided, and at least a surface of the pressure roller is made of ultrahigh molecular weight polyethylene.
A toner image on the recording material by a pressure roller having at least a surface made of ultra-high molecular weight polyethylene and a back roller facing the pressure roller in the traveling direction of the recording material and downstream of the fixing unit. The fixing method according to any one of (1) to (3), wherein the pressure is applied.

(5) The image forming apparatus according to (4), further comprising a bias applying unit that applies a bias having the same polarity as the toner transferred onto the recording material to the pressure roller.
The fixing method according to (4), wherein a bias having the same polarity as the toner transferred onto the recording material is applied to the pressure roller.

(6) The above (2), characterized by comprising a cleaning means for cleaning the surface of the ultra high molecular weight polyethylene roller in contact with the roller, and the cleaning means having a mechanism for contacting and separating from the roller. To (4).
Any one of (2) to (4) above, wherein the surface of the ultra high molecular weight polyethylene roller is brought into contact with the surface of the ultra high molecular weight polyethylene roller by a cleaning unit having a mechanism for contacting and separating from the roller. Fixing method.

(7) The image forming apparatus according to (6), wherein the pressure roller cleaning means is a web.
The fixing method according to (6), wherein a web is used as a cleaning unit for the pressure roller.

(8) The above (7), wherein a backup roller that contacts the pressure roller via the web is provided, and the backup roller has a mechanism that contacts and separates from the pressure roller via the web. The image forming apparatus described.
The fixing method according to (7), wherein a backup roller comes in contact with and separates from the pressure roller through the web.

  According to the present invention, at least the surface of the member that comes into contact with the fixing liquid application surface of the recording material is made of ultrahigh molecular weight polyethylene, and the fixing liquid is brought into contact with the fixing liquid application surface of the recording material after application of the fixing liquid. It is possible to improve the change over time and the durability of the roller means for applying and pressurizing.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 is a conceptual diagram showing an embodiment of an image forming apparatus according to the present invention, and shows a color electrophotographic tandem type image forming apparatus used as a copying machine or a printer. FIG. 3 shows a part of the image forming apparatus shown in FIG.

As shown in FIG. 2, the image forming unit is provided with an intermediate transfer belt 11 as a toner image carrier. The intermediate transfer belt 11 is stretched around three support rollers 12, 13, and 14, and is configured to rotate clockwise. In the transport direction of the intermediate transfer belt 11, black (Bk), yellow (Y), magenta (M), and cyan (C) image forming units 15Bk, 15Y, 15M, and 15C are arranged. Above these image forming units 15Bk, 15Y, 15M and 15C, an exposure device (not shown) is arranged. For example, in the case of a copying machine, image information of a document is read by a scanner, and light L for writing an electrostatic latent image on the photosensitive drum 16 (16Bk, 16Y, 16M, 16C) is exposed according to the image information. Irradiated by the device (see FIG. 3).
A secondary transfer device 17 is provided at a position facing the support roller 14 of the intermediate transfer belt 11. The secondary transfer device 17 is composed of a secondary transfer belt 20 stretched between two support rollers 18 and 19. The secondary transfer device 17 may have a configuration using a transfer roller in addition to the transfer belt. A belt cleaning device 21 is disposed at a position facing the support roller 12 of the intermediate transfer belt 11. The belt cleaning device 21 is arranged to remove the toner remaining on the intermediate transfer belt 11.
The recording material (recording paper) 22 is guided to the secondary transfer portion by a pair of paper feed rollers 23, and the secondary transfer belt 20 is pressed against the intermediate transfer belt 11 when the toner image is transferred to the recording material 22. Transfer. The recording material 22 onto which the toner image has been transferred is guided to the fixing device 30 and a fixing solution is attached thereto.

Next, the image forming unit will be described.
FIG. 3 is a partially enlarged view of the image forming apparatus shown in FIG. FIG. 1 is a schematic configuration diagram illustrating an example of a fixing unit and a pressure unit according to the present invention. 4A and 4B are explanatory diagrams showing a state in which the fixing liquid is applied to the toner on the recording material, and the toner is softened or swelled. FIG. 4A shows a state before fixing, and FIG. 4B shows a softened state. Alternatively, swelling is shown, and FIG. 4C shows the completion of fixing.
As shown in FIGS. 3 and 1, in the image forming unit, a charging device 24, a developing device 25, a cleaning device 26, and a charge eliminating device 27 are disposed around the photosensitive drum 16. Further, a primary transfer device 28 is provided at a position facing the photoconductor 16 through the intermediate transfer belt 11.
The charging device 24 is a contact charging system that employs a charging roller, and uniformly charges the surface of the photosensitive drum 16 by applying a voltage by contacting the photosensitive drum 16. As the charging device 24, a non-contact charging type charging device employing non-contact scorotron charging or the like may be employed.

  The developing device 25 causes the toner in the developer to adhere to the latent image on the photosensitive drum 16 to make it visible. Here, the toners corresponding to the respective colors are made of resin materials colored in the respective colors, and are formed so as to be softened or swelled by a fixing liquid described later (see FIGS. 4A to 4C). The developing device 25 includes a stirring unit and a developing unit (not shown), and the developer that has not been used for development is returned to the stirring unit and reused. The toner concentration in the stirring unit is detected by a toner concentration sensor, and is controlled so that the concentration becomes constant.

  The primary transfer device 28 transfers the toner visualized on the photosensitive drum 16 to the intermediate transfer belt 11. Here, as the primary transfer device 28, a transfer roller method is adopted, and the primary transfer device 28 is disposed so as to be pressed against the photosensitive drum 16 with the intermediate transfer belt 11 interposed therebetween. As the primary transfer device 28, a conductive brush shape, a non-contact corona charger, or the like can also be employed.

  The cleaning device 26 removes unnecessary toner on the photosensitive drum 16. As the cleaning device 26, a blade configured so that the tip is pressed against the photosensitive drum 16 can be used. Here, the collected toner can be collected in the developing device 25 by a collection screw (not shown) or a toner recycling device, and can be reused.

  The neutralization device 27 is constituted by a lamp, and initializes the surface potential of the photosensitive drum 16 by irradiating light.

Next, the fixing device 30 for attaching the fixing liquid to the toner will be described.
As shown in FIG. 1, the fixing solution is stored in a fixing solution filling tank 31 and connected to a fixing solution application pad 32 through a transport pipe. A small amount of fixing solution is supplied to the coating roller 33 from the fixing solution coating pad 32 containing the fixing solution to the coating roller 33 which is a means for attaching the fixing solution, and the coating roller 33 and the pressure roller 34 are in contact with each other. The fixing liquid is applied to the unfixed toner 36 on the recording material (recording medium) 35 at the part. Here, the recording material 35 such as paper is one to which toner has been attached in the above-described image forming process. The application roller 33 is processed from a block of ultra high molecular polyethylene.

Here, the ultra high molecular weight polyethylene will be described.
The ultra high molecular weight polyethylene used in the present invention has a high molecular weight of 1 million to 6 million. As a commercial product, Sakushin Kogyo's ultra high molecular weight polyethylene “trade name New Light” is available.
As its characteristics,
(1) The attached toner is easy to peel off.
(2) Swelling and dissolution do not occur even if a solvent is attached.
(3) Since the volume resistance value can be controlled and the resistance can be selected up to 103 Ω · cm, there is an advantage that a bias can be applied from the shaft core, and an effective performance can be obtained by a cleaning means with a simple configuration.

Thus, when ultra high molecular weight polyethylene is used as the roller, the volume resistance can be lowered to 10 ³ Ωcm, so that a bias can be applied and offset can be prevented. In particular, since a bias can be applied from the cored bar, a highly reliable configuration as a contact is possible.

  Further, if not only the application roller 33 but also the surface of the pressure roller 34 facing the application roller 33 is made of ultra-high molecular weight polyethylene, the softening liquid applied by the application roller 33 will be on both ends of the recording material 35 outside the size. In addition, it is possible to clean the softening liquid adhering to the contact between the papers. Further, in order to maintain the feeding speed of the recording material 35, the opposing roller is also required to have mechanical accuracy such as an outer dimension and a coaxial degree, but it can also be met. Furthermore, the outer dimensions should not swell, and mechanical strength is also required as nip formation with the application roller 33, but any of these can be accommodated.

Next, it can be seen that the pressurizing means of the present invention is arranged in the recording material conveyance path after the fixing solution is applied (see FIG. 1).
The pressurizing means 37 after applying the fixing solution has an effect of accelerating the softening of the toner (an effect such as pushing the toner into the paper fiber), but it is not necessarily in the subsequent process of the applying means, and the printing speed and the subsequent process. The necessity depends on various conditions such as the distance to and the softening speed of the softener.
Here, the pressurizing means 37 as an auxiliary mechanism will be described.
The pressure unit 37 includes a pressure roller 38 that comes into contact with the toner image surface and a back roller 39 that faces the pressure roller 38. The pressure setting varies depending on the machine conditions. The effect by this pressurizing means 37 is considered as follows.

  In other words, after the application roller 33 has passed, if the fixing is not completed before the next mechanical part is contacted, problems such as rubbing occur. Further, it is necessary to prevent the above problems from occurring during fixing. Although it is known to pressurize the coated surface as a means for promoting fixing, it is necessary to prevent offset because it is in the middle of fixing.

Therefore, if the pressure roller 38 is made of ultra high molecular weight polyethylene, the offset can be reduced. However, cleaning is necessary because it is not perfect, but a cleaning means with a low load is sufficient. In addition, when the toner is being softened, the visualized toner image can be traced on the surface of the smooth roller, and as a result, the reflection density is increased due to the flat state. can do.
The back roller 39 facing the pressure roller 38 may also be an ultra high molecular weight polyethylene roller or a roller having an intermediate resistance (10 ⁹ to 10 ¹² Ω · cm).

As described above, the advantage of pressurization is great. However, by applying pressure, the toner tends to adhere to the surface. Moreover, if it is softening, the viscosity will also become high and it will adhere easily to the roller surface. Actually, when tested with an ultra-high molecular weight polyethylene roller, a visualized toner image that hardly adheres at a pressure of about its own weight is attached when the pressure is increased. Although the absolute amount is small (the relationship between the pressure and the adhesion amount is not specifically measured and is based on sensory evaluation), it is offset if there is no cleaning.
Accordingly, the pressure roller 34 is provided with a web cleaning member (web) 40 as a cleaning means. In addition, a bias having the same polarity as the toner is applied to the pressure roller 38 as an offset prevention means. Here, a stable roller configuration can be applied from the metal core, and the wrinkle of the film due to many factors such as pressure distribution and mechanical accuracy is taken into consideration even if the applied pressure is higher than that coated with a tube etc. Can do.

As described above, a reverse bias can be applied to the pressure roller 38 to reduce the degree of offset. In that case, the ground is removed from the core bar, so the reliability is high.
Further, when the recording material 35 is a sheet of paper, there is a gap between sheets in continuous paper passing, and depending on the size, contact between both ends occurs in the configuration with the opposing roller (back roller 39 in the figure). The opposing roller is grounded with respect to the bias, but if the resistance value is low, it leaks and is not easily applied to the recording material to be originally applied.

Therefore, as described above, it is important that the facing roller is a roller means having a medium resistance value. According to this ultra-high molecular weight polyethylene, a resistance value of 10 ³ to 10 ¹⁷ Ω · cm can be selected, so that it can be a counter roller as a medium resistance roller. In addition, it is possible to drop the roller from the cored bar part to the ground, so that stable quality can be maintained. This is because normal terminals can be used.

  As described above, even with ultra-high molecular weight polyethylene, a small amount of toner adheres. And if there is no cleaning mechanism, it will be offset. A cleaning unit that cleans the surface by contacting the surface of the pressure roller 38 made of ultrahigh molecular weight polyethylene as shown in FIG. 1 is installed, and the offset toner to which the softening liquid is attached is collected to perform stable pressing. be able to. However, since the softening agent is included, it is necessary to move the cleaning means to a position separated from the pressure roller 38 when the machine is stopped. This is because the fixing means is stuck between the cleaning means and the pressure roller 38.

  It is preferable to use the web 40 as the cleaning means that is separated from the surface of the pressure roller 38. By using the web 40 and collecting the collected toner while winding it, the roller surface can be constantly cleaned even in a new part. . Further, the portion of the web 40 that is in contact is separated when the machine is stopped. However, if the web 40 is wound up to a new surface and stopped, it is not necessary to separate it.

Further, by pressing a pressing roller 41 made of, for example, sponge from the back surface of the web 40 against a portion that comes into contact with the pressing roller 38, the adhesion between the web 40 and the pressing roller 38 is increased, and the pressing roller 38 is increased in the width direction. The variation of can be eliminated. Further, a mechanism for contacting and separating the presser roller 41 from the back surface is provided in order to avoid the continuous contact state of the web 40 when the machine is stopped or the power is turned off. The release amount of the presser roller 41 may be small, and a back tension is always applied to the feed roller 42 of the web 40, so there is no risk of looseness. Reference numeral 43 denotes a take-up roller for winding the web 40, and reference numeral 44 denotes a cleaning blade for removing excess fixing solution.
Although the web 40 contacts and separates, the contact requires a pressure at the nip as a cleaning effect, and this pressure can reduce variations in cleaning performance in the width direction. Naturally, the pressurizing means 37 is also separated from the pressurizing position when the web is separated.

Next, examples of softeners are shown.
The softening agent contained in the fixing liquid is a material that softens or swells the resin component constituting the toner (hereinafter referred to as “softening agent”). As the softening agent, an aliphatic ester can be used.

  In the present invention, the aliphatic ester preferably contains a saturated aliphatic ester. Thereby, storage stability (resistance to oxidation and hydrolysis) can be improved. Further, the safety to the human body is high, and the resin contained in the toner can be dissolved or swollen within 1 second. Furthermore, the saturated aliphatic ester has less stickiness in the toner layer after the solvent has evaporated. This is considered to be because an oil film is formed on the surface of the toner layer in which the saturated aliphatic ester is softened.

In the present invention, the saturated aliphatic ester has the general formula (1)
R ₁ COOR ₂ (1)
It is preferable that R ₁ is an alkyl group having 11 to 14 carbon atoms, and R ₂ is an alkyl group having 1 to 3 carbon atoms. Thereby, the solubility with respect to the resin contained in a toner can be improved. Further, the odor index is 10 or less, and there is no unpleasant odor or irritating odor.

  Examples of the aliphatic monocarboxylic acid ester include ethyl laurate, hexyl laurate, ethyl tridecylate, isopropyl tridecylate, ethyl myristate, isopropyl myristate, and the like. As the resin contained in the toner, polystyrene resin, styrene-acrylic copolymer resin, and polyester resin are suitable. Further, the toner may have a wax component such as polyethylene.

In the present invention, the aliphatic ester preferably contains an aliphatic dicarboxylic acid ester.
In the present invention, the aliphatic dicarboxylic acid ester has the general formula (2)
R ₃ (COOR ₄ ) ₂ (2)
R ₃ is preferably an alkylene group having 3 to 8 carbon atoms, and R ₄ is preferably an alkyl group having 2 to 5 carbon atoms. Thereby, the solubility with respect to the resin contained in a toner can be improved. Further, the odor index is 10 or less, and there is no unpleasant odor or irritating odor.
Examples of the aliphatic dicarboxylic acid ester include diethyl succinate, diethyl adipate, diisobutyl adipate, diisopropyl adipate, diisodecyl adipate, diethyl sebacate, dibutyl sebacate and the like. The resin contained in the toner is the same as described above.

  In the present invention, the aliphatic ester preferably contains a dialkoxyalkyl aliphatic dicarboxylate. Thereby, the fixing property of the toner can be improved. Since the aliphatic dicarboxylic acid dialkoxyalkyl is slightly soluble in water, when water is used as a solvent, it is easily retained in a soluble state.

In the present invention, the dialkoxyalkyl aliphatic dicarboxylate has the general formula (3)
R ₅ (COOR ₆ —O—R ₇ ) ₂ (3)
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 one or more carbon atoms. The alkyl group is preferably 4 or less. Thereby, the solubility with respect to the resin contained in a toner can be improved. Further, the odor index is 10 or less, and there is no unpleasant odor or irritating odor.

  Examples of the aliphatic dicarboxylic acid dialkoxyalkyl include diethoxyethyl succinate, dibutoxyethyl succinate, diethoxyethyl adipate, dibutoxyethyl adipate, diethoxyethyl sebacate and the like.

In the present invention, the odor index of the aliphatic ester is preferably 10 or less. This eliminates discomfort in a normal office environment. If the aliphatic ester and the solvent have an unpleasant odor or an irritating odor, they are not suitable for use in an office environment or the like. In particular, since the aliphatic ester remains in the toner even after the toner is fixed, it is not preferable in use to have an unpleasant odor or an irritating odor.
In addition, the odor index (10log (dilution rate until no odor is lost)) by the three-point comparison odor bag method, which is a sensory measurement, is used as an odor indicator as a highly accurate and practical odor measurement scale in office environments. ing.
Further, if the solvent has an unpleasant odor or an irritating odor, an odor is generated from the apparatus during fixing. Since the solvent has a large content in the fixing solution, the odor index is preferably 7 or less, and more preferably 3 or less.

  Next, a diluent for diluting the softener or a dispersion for dispersing the softener will be described. When a softener is used as the fixer, a diluent is sometimes required. Considering the place of the softener after dissolution and swelling, it is desirable that the softener can be supplied in a thin and small amount, but it is extremely difficult to supply the softener in a small amount and uniformly. Therefore, as a method for supplying such a small amount of softener, a method of diluting the softener with some liquid is generally used.

  At this time, when the diluent is attached to the resin, the diluent preferably contains a substance that does not lower the amount of heat necessary for melting the resin. If possible, it is best to use only substances that do not reduce the amount of heat required for melting the resin. As described above, by measuring the amount of heat necessary for melting the resin when the softener is attached to the resin, the proper amount of the softener is grasped, and when using an appropriate amount of the softener, If a diluent that lowers the amount of heat required for melting is used, the amount of softening agent will seem to increase.

  In other words, the softening force is too much, which is advantageous for softening and swelling of the resin, but is disadvantageous in that it takes time for subsequent solidification. The amount of heat necessary for melting the softener and diluent, or the softener, diluent and other components that are attached to the resin as the fixing solution is zero or the amount of heat necessary to obtain the desired fixability. Although there is a method to determine the amount of softening agent from the amount of heat necessary for melting the resin, using a diluent that does not affect the amount of heat necessary for melting the resin, it is better to determine the dilution rate only for convenience of use, Convenient.

When the present invention is used for a dry toner, it is preferable that water is contained as a diluent solvent in a configuration in which the fixing solution contains a diluent solvent. Thereby, the odor of the fixing solution can be greatly reduced. Also, water is not applicable to volatile organic compounds (VOC) and is extremely advantageous for the office environment. However, since the solubility of the aliphatic ester in water is generally low, it is necessary to maintain the aliphatic ester in a soluble state in water or in a dispersed state in fine particles.
Examples of such a method include a method of adding a surfactant having an HLB value of about 5 to 16 to water, adding an aliphatic ester, and then stirring for a long time while heating. Surfactants having an HLB value of about 5 to 16 include sucrose fatty acid esters such as sucrose citrates such as sucrose laurate, sucrose myristate, and sucrose stearate, and sorbitan fatty acid esters. Examples thereof include sorbitan monooleate, sorbitan trioleate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monopalmitate, glycerin fatty acid esters and the like.
Moreover, a mixed solvent of water and a water-soluble solvent can also be used as a dilution solvent. Examples of the water-soluble solvent include monovalent alcohols such as ethanol and isopropanol, and polyhydric alcohols such as propylene glycol, 1,3 butylene glycol and glycerin.

  In the present invention, the good solvent for the aliphatic ester may be a hydrophobic solvent. Examples of such solvents include silicone oils, olefin solvents, paraffin solvents, fluorine solvents, and the like, and it is preferable to select from solvents having an LD50 of greater than 3 g / kg. As silicone oils, polydimethylsiloxane, methylcyclosiloxane tetramer, pentamer and the like having a viscosity of about 1 to 10 mPa · s are suitable. As paraffin type, n-decane, n-dodecane, n-undecane and the like are suitable. As the olefin solvent, poly α-oxyethylene or the like is suitable. As the fluorinated solvent, hydrofluoroether or the like is suitable. These hydrophobic solvents are desirably non-volatile and have a boiling point of 260 ° C. or higher under atmospheric pressure.

  In the present invention, the aliphatic ester, which is a softening agent for a resin contained in a toner or the like, may be a gel-like liquid or a semi-solid such as wax in addition to a fluid liquid. The viscosity of the aliphatic ester is preferably 1 mPa · s or more and 100 Pa · s or less.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

  The present invention will be specifically described below with reference to examples. However, the present embodiment is merely illustrative of the present invention, and the present invention is not limited by these embodiments.

  The fixing unit of the Ricoh color printer (CX8800) is modified to the fixing unit and the pressing unit shown in FIG. 1, and image formation is performed using the toner for the Ricoh color printer (Ipsio Color toner 9800, resin: polyester resin). Then, a fixer having the following formulation was applied to the toner on the recording material and pressurized.

The application roller of the fixing unit was prepared using an ultra-high molecular weight polyethylene block (manufactured by Sakushin Kogyo Co., Ltd., trade name: Newlite). Further, the pressure roller of the pressure means was also prepared using the new light block.
In addition, when the fixing solution is applied to the toner layer, the ratio of the softening agent to the toner on the paper is 9 wt% after the diluted solvent in the fixing solution evaporates or diffuses into the paper. Fixing was performed. The application amount of the fixing solution was 0.5 g to 0.6 g / A4.
(Fixing solution formula)

Softener: Diisobutyl adipate (higher alcohol industry) 5wt%
Diluting solvent
Water 19wt%
Propylene glycol 75wt%
Penetration agent: Polyether-modified silicone (Toray Dow Corning) 1wt%
Stirring while adding the softening agent dropwise to the dilution solvent, the softening agent was mixed with the dilution solvent. The mixed state was a microemulsion state.
(Fixation test)

Output image: Solid black (toner amount on paper: 0.2 g / A4)
Fixing evaluation: 10 seconds after application, rubbing the toner surface with a waste, and judging by image deterioration (test result)

  10 seconds after application, the toner surface was rubbed with a waste cloth, and it was confirmed that the image was not disturbed and good fixing was performed.

In the same manner as in Example 1, the toner is applied to the toner layer with the following fixer formulation. When the fixer is applied, the diluted solvent in the fixer evaporates or diffuses into the paper, and then the toner on the paper Fixing was performed so that the ratio of the softening agent was 6 to 7 wt%. The coating amount of the fixing solution was 0.15 g to 0.2 g / A4.
(Fixing solution formula)

Softening agent: Diethoxyethyl succinate (Croda) 10wt%
Diluting solvent
Water 54wt%
Propylene glycol 35wt%
Penetration agent: Polyether-modified silicone (Toray Dow Corning) 1wt%
Stirring while adding the softening agent dropwise to the dilution solvent, the softening agent was mixed with the dilution solvent. The mixed state was a dissolved state.
(test results)

  10 seconds after application, the toner surface was rubbed with a waste cloth, and it was confirmed that the image was not disturbed and good fixing was performed.

In the same manner as in Example 1, the toner is applied to the toner layer with the following fixer formulation. When the fixer is applied, the diluted solvent in the fixer evaporates or diffuses into the paper, and then the toner on the paper Fixing was performed so that the softener ratio was 11 to 12 wt%. The coating amount of the fixing solution was 0.6 g to 0.7 g / A4.
(Fixing solution formula)

Softener: Diethylhexyl succinate (higher alcohol industry) 5wt%
Diluting solvent
Water 19wt%
Propylene glycol 75wt%
Penetration agent: Polyether-modified silicone (Toray Dow Corning) 1wt%
Stirring while adding the softening agent dropwise to the dilution solvent, the softening agent was mixed with the dilution solvent. The mixed state was a microemulsion state.
(test results)

  10 seconds after application, the toner surface was rubbed with a waste cloth, and it was confirmed that the image was not disturbed and good fixing was performed.

FIG. 5 is a conceptual diagram showing another embodiment of the image forming apparatus according to the present invention.
Using the liquid developing type image forming apparatus shown in FIG. 5, only the pressurizing means shown in FIG. 1 is attached downstream of the fixing liquid application unit including the supply roller 50, the fixing roller 51, and the opposing roller 52, and the experiment is performed. It was.
Note that the supply roller 50 and the pressure roller of the pressure means were made using a block of ultrahigh molecular weight polyethylene (trade name: Newlite) manufactured by Sakushin Kogyo Co., Ltd.
Development is performed using a liquid developer 53 in which toner is dispersed in dimethylpolysiloxane oil having a viscosity of 50 mPa · s as a carrier liquid, and the toner image on the formed recording material 35 is the same as that used in Example 1. A fixer was applied and pressed with a pressure roller.
The obtained image was subjected to a fixing test by rubbing the toner surface with a waste cloth 10 seconds after the application, and it was confirmed that the image was not disturbed and was fixed satisfactorily.
Reference numeral 54 denotes a coating device that applies the liquid developer 53 to the photosensitive member 16, and includes an intermediate roller 55, a cleaning blade 56, and a coating roller 57. A developing roller 58 applies the liquid developer 53 from the coating device 54 to the photosensitive member 16. A cleaning blade 59 removes excess liquid developer on the photosensitive member 16 via the sweep roller 60. A cleaning blade 61 removes excess liquid developer from the liquid developer transferred from the photoreceptor 16 to the intermediate transfer roller 62. Reference numeral 63 denotes a transfer roller.

[Function and effect]
According to the first and second aspects of the present invention, after the fixing solution is applied to the toner on the recording material, at least the surface of the member that comes into contact with the fixing solution application surface, for example, the fixing solution application roller, is made of ultrahigh molecular weight polyethylene. Therefore, not only the toner does not adhere easily, but the volume resistance of the roller can be lowered to 10 ³ Ω · cm, so that a bias can be applied and offset prevention can be performed. In particular, since a bias can be applied from a cored bar, a highly reliable configuration as a contact is possible.

  According to the third aspect of the present invention, the surface of the facing roller facing the fixing liquid application roller is made of ultra-high molecular weight polyethylene, so that not only the fixing liquid adhered from the coating roller can be cleaned but also required for the facing roller. It is possible to cope with mechanical accuracy and mechanical strength.

  According to the fourth aspect of the present invention, since the surface of the pressure roller of the pressure unit provided on the downstream side of the fixing unit is made of ultra high molecular weight polyethylene, it is difficult to avoid toner adhesion due to pressure, but the absolute amount is small. can do.

  According to the fifth aspect of the invention, the bias having the same polarity as the toner on the recording material is applied to the pressure roller, so that the offset can be reduced.

  According to the sixth aspect of the present invention, since the cleaning means for contacting the surface of the ultra high molecular weight polyethylene roller to clean the roller surface is provided and the contact / separation mechanism for contacting / separating the roller surface to the cleaning means is provided, the fixing solution adheres. Not only can the offset toner be recovered to perform stable pressurization, but also the cleaning means and the roller can be prevented from sticking when the machine is stopped.

  According to the seventh aspect of the present invention, since the cleaning means for the pressure roller is a web, the recovered toner is collected while being wound up. Therefore, the roller surface can be constantly cleaned at a new portion and is in contact therewith. The web part is separated when the machine is stopped, and it is not necessary that the web part is separated when the winding is stopped to a new surface.

  According to the eighth aspect of the present invention, the backup roller (see the presser roller in FIG. 1) that contacts the pressure roller via the web is provided, and the backup roller has a mechanism that contacts and separates from the pressure roller via the web. Therefore, it is possible to apply a pressure at the nip portion necessary for cleaning to the web, and this pressure can reduce variations in the cleaning performance in the width direction. As a matter of course, the backup roller is separated from the pressure position when the web is separated.

It is a schematic block diagram which shows an example of the fixing means and pressurizing means which concern on this invention. 1 is a conceptual diagram illustrating an embodiment of an image forming apparatus according to the present invention, and is a diagram illustrating a color electrophotographic tandem image forming apparatus used as a copying machine or a printer. FIG. 3 is a diagram illustrating a part of the image forming apparatus illustrated in FIG. 2. 4A and 4B are explanatory diagrams showing a state in which a fixing liquid is applied to toner on a recording material, and the toner is softened or swollen. FIG. 5A shows before fixing, FIG. 5B shows softening or swelling, and FIG. ) Indicates completion of fixing. It is a conceptual diagram which shows the other Example of the image forming apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 15 Image formation unit 16 Photosensitive drum or latent image carrier 17 Secondary transfer apparatus 28 Primary transfer apparatus 30 Apparatus which adheres fixing liquid to toner

Claims (16)

The electrostatic latent image on the latent image carrier is developed with toner, the developed toner image is transferred onto a recording material, and a fixing solution for softening or swelling the toner is applied to the toner image transferred onto the recording material. A fixing method for fixing a toner image on the recording material,
A fixing method comprising: forming at least a surface of a member in contact with a fixing liquid application surface of the recording material from ultra high molecular weight polyethylene, and contacting the fixing liquid application surface of the recording material after application of the fixing liquid.   Using fixing means comprising a fixing liquid application roller and an opposing roller facing the fixing liquid application roller, and using the fixing liquid application roller as a member that comes into contact with the fixing liquid application surface of the recording material after application of the fixing liquid. The fixing method according to claim 1, wherein:   Using fixing means comprising a fixing liquid application roller and an opposing roller facing the fixing liquid application roller, and using the fixing liquid application roller as a member that comes into contact with the fixing liquid application surface of the recording material after application of the fixing liquid. The fixing method according to claim 1, wherein:   A toner image on the recording material by a pressure roller having at least a surface made of ultra-high molecular weight polyethylene and a back roller facing the pressure roller in the traveling direction of the recording material and downstream of the fixing unit. The fixing method according to claim 1, wherein pressure is applied.   The fixing method according to claim 4, wherein a bias having the same polarity as that of the toner transferred onto the recording material is applied to the pressure roller.   5. The roller surface according to claim 2, wherein the surface of the ultra high molecular weight polyethylene roller is brought into contact with the surface of the ultra high molecular weight polyethylene roller by a cleaning unit having a mechanism that contacts and separates from the roller. Fixing method.   The fixing method according to claim 6, wherein a web is used as cleaning means for the pressure roller.   The fixing method according to claim 7, wherein a backup roller contacts and separates from the pressure roller through the web.   A latent image carrier, a developing unit that develops the electrostatic latent image on the latent image carrier with toner, a transfer unit that transfers the developed toner image onto a recording material, and the image transferred onto the recording material An image forming apparatus comprising: a fixing unit that applies a fixing liquid that softens or swells toner to a toner image and fixes the toner image on the recording material, wherein the fixing liquid is applied to the recording material after the fixing liquid is applied. An image forming apparatus, wherein at least a surface of a member in contact with the surface is made of ultrahigh molecular weight polyethylene.   The fixing unit includes a fixing liquid application roller and a facing roller facing the fixing liquid application roller, and the member that contacts the fixing liquid application surface of the recording material after the fixing liquid application is the fixing liquid application roller. The image forming apparatus according to claim 9.   The image forming apparatus according to claim 10, wherein at least a surface of the facing roller is made of ultra high molecular weight polyethylene.   A pressure unit including a pressure roller that presses the toner image on the recording material and a back roller facing the pressure roller in a traveling direction of the recording material and downstream of the fixing unit; The image forming apparatus according to claim 9, wherein at least a surface of the pressure roller is made of ultra high molecular weight polyethylene.   The image forming apparatus according to claim 12, further comprising a bias applying unit that applies a bias having the same polarity as the toner transferred onto the recording material to the pressure roller.   13. The cleaning device according to claim 10, further comprising a cleaning unit that contacts the surface of the ultra high molecular weight polyethylene roller to clean the surface of the roller, and the cleaning unit has a mechanism that contacts and separates from the roller. The image forming apparatus according to claim 1.   15. The image forming apparatus according to claim 14, wherein the pressure roller cleaning means is a web.   16. The apparatus according to claim 15, further comprising a backup roller that contacts the pressure roller via the web, and the backup roller has a mechanism that contacts and separates from the pressure roller via the web. Image forming apparatus.

Images