JP2007047365A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which prevents a paper jam due to a separating plate, allows easy peeling and release of recording paper on which a toner image has been fixed from the fixing device, and can prevent toner sticking on the separating plate and peeling of a coating member from the separating plate. <P>SOLUTION: The fixing device comprises a fixing roller 201 and a pressure roller 202 forming a nip portion 205, and the separating plate 203 disposed in noncontact with the fixing roller 201 and the pressure roller 202 and used to release a recording medium on which a toner image has been fixed through the nip portion 205 from the fixing roller 201 or the pressure roller 202, wherein the maximum value of pressure distribution in the nip portion 205 along a direction of movement of the recording medium is made to exist on an outlet side of the nip portion 205 rather than the midway point between the inlet and outlet of the nip portion 205. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device for fixing a toner image transferred to a recording paper on the recording paper in an image processing apparatus equipped with an electrophotographic image forming process, and an image forming apparatus to which the fixing device is applied.

A recording medium (hereinafter also simply referred to as recording paper) onto which a toner image has been transferred is formed by a nip formed by a fixing belt or fixing roller as a fixing member and a pressure roller as a pressure member in contact therewith. In an electrophotographic image forming apparatus having a fixing device that clamps and applies heat and / or pressure to fix the toner image on the recording paper, the recording paper on which the toner image is fixed has an adhesive force of toner. May wrap around the fixing belt or the fixing roller and be discharged from the nip portion as it is, resulting in poor separation. Further, when printing on both sides of the recording paper, the recording paper may wind around the pressure roller and cause separation failure.
As a method for avoiding such recording paper separation failure, the separation claw is brought into contact with the surface of the fixing member immediately after the exit of the nip portion, that is, the fixing belt, the fixing roller, or the pressure roller, and is discharged in a wound state. There is a method for forcibly removing the recording paper to be released. However, in this method, the surface of the fixing belt or the fixing roller may be scratched (claw marks) by being scraped by the separation claw, which may cause image defects.

Therefore, a method using a separation plate instead of the separation claw has been adopted. A plurality of separation claws are in contact with the image passing portion on the surface of the fixing member, whereas a separation plate is installed in a non-contact state with respect to the fixing member at the image passing portion. In some ways they are different. Accordingly, it is possible to prevent the fixing belt and the like from being damaged. However, the method using the separation plate has the following problems. In other words, the toner may adhere to the paper passing surface of the separation plate with time, and the attached toner may be retransferred to another recording paper, resulting in image defects. In addition, the gap between the separation plate and the fixing member may deviate from the design value, and the paper may enter the gap and wind around the fixing member.

In order to avoid such a problem, a technique for keeping the gap between the separation plate and the fixing member constant has been proposed. That is, Patent Document 1 discloses that
An apparatus developed for the purpose of providing a fixing device that maintains good print quality without damaging the fixing roller, the fixing member being in pressure contact with the pressure member, and a recording medium adjacent to the fixing member A separation plate disposed in a direction crossing the conveyance direction, disposed at a longitudinal end portion of the separation plate, and contacting the fixing member to thereby provide a gap between the fixing member and the separation plate. There is disclosed a fixing device provided with a spacer for maintaining a predetermined width.

By the way, when toner containing wax is used as a developer, a large amount of oil such as silicone oil for improving releasability is applied to the surface of the fixing member in order to prevent the recording paper from being wound around the fixing member. Although not necessary, it is not sufficient to use waxed toner in order to achieve oil-less operation.
Therefore, even when wax-containing toner is used, a separation plate is provided close to the surface of the fixing member, and the separation plate prevents the recording paper from being wrapped around the fixing member. However, in order to enhance the effect of preventing the recording paper from being wrapped by the separating plate, it is necessary to make the gap between the separating plate and the surface of the fixing member extremely narrow, and it is not easy to maintain the narrow gap accurately for a long period of time. In order to realize this, the manufacturing cost of the fixing device increases. In order to solve such a problem, Patent Document 2 discloses that a recording paper on which a toner image formed with wax-containing toner is transferred is passed between first and second fixing members, and heat and pressure are applied. A fixing device for fixing the toner image onto a recording paper, wherein the first and second fixing members are a base, an elastic layer provided on the base, and an elastic layer on the base; A separation layer for separating the recording paper is placed in contact with and disposed on at least one surface of the first and second fixing members, and the surface of the first and second fixing members is provided. A fixing device is disclosed in which an oil-impregnated application member for applying a small amount of oil is provided on at least one surface.

  Further, Patent Document 3 discloses an apparatus developed for the purpose of preventing a problem that the recording paper is wound around the surfaces of the fixing member and the pressure member, and includes a rotatable fixing member and a pressure contact with the fixing member. And a pressure member that forms a nip portion, and passes a recording paper carrying a toner image through the nip portion and fixes the toner image onto the recording paper by the action of heat and pressure. In order to form a convex nip by setting the surface hardness of the pressure member higher than the surface hardness of the fixing member, and to separate the recording material discharged from the convex nip from the surface of the pressure member Is separated between the pressure member surface and the front end of the recording material, and when the trailing edge of the front end margin of the recording material reaches the exit of the convex nip portion. The leading edge of the recording paper and the rotation center of the pressure member On the line, the fixing device is disclosed that the separating means leading end is configured to be positioned.

JP 2003-202767 A JP 2004-191520 A JP 2003-316197 A

3 and 4 are explanatory views showing the nip portion of the fixing device in the prior art. FIG. 3 is a view showing the nip portion between the fixing belt 303 and the pressure roller 302. FIG. 2 is a diagram showing a nip portion between the pressure roller 402 and the pressure roller 402. FIG. 3 and 4, the angles of the pressing directions 307 and 404 with respect to the recording paper moving directions 308 and 406 at the nip portion, which is the contact portion between the fixing belt or the fixing roller and the pressure roller, are about 90 degrees, respectively. Therefore, the pressure peak of the contact pressure in the nip portion exists in the center portion of the nip portion width along the recording paper moving direction (see FIG. 4). When the pressure peak exists at the center of the nip as described above, the toner pressurized at the center of the nip adheres to the recording paper and is simultaneously conveyed to the fixing member surface layer to the nip outlet, and the pressure is reduced at the nip outlet. Therefore, the recording paper goes to the separation plate without separating the curvature, and paper separation is performed by using the leading edge margin of the recording paper by the separation plate. Here, when the adhesive force of the toner to the fixing member is strong, the recording paper is wound around the fixing member and conveyed, so that the opportunity for separating the transfer paper with the separating plate increases, and the toner adheres to or separates from the separating plate. There arises a problem that the fluorine coating or the fluororesin tape applied to the plate is worn.

The present invention has been made in view of such problems of the prior art, eliminates paper jam caused by the separation plate, and can easily peel and remove the recording paper on which the toner image is fixed from the fixing device, It is another object of the present invention to provide a fixing device and an image forming apparatus that can prevent the toner from adhering to the separation plate and the coating member from peeling off from the separation plate.

In order to achieve the above object, a fixing device according to the present invention is arranged in a non-contact manner with respect to a fixing member and a pressure member that form a nip portion, and to the fixing member and the pressure member, and passes through the nip portion. In the fixing device including the separation plate for separating the recording medium on which the toner image is fixed from the fixing member or the pressure member, the maximum value of the pressure distribution along the moving direction of the recording medium in the nip portion is It exists in the nip part exit side rather than the intermediate point of the entrance and exit of the said nip part.
In this case, the fixing member and the pressure member are, on a cross-sectional view orthogonal to the rotation axis of the fixing member or the pressure member, a vertical line passing through the rotation axis of the fixing member, and the recording medium in the nip portion. An intersection point (P1) with a straight line indicating the moving direction is an intersection point (P1) between a straight line connecting the rotating shaft of the fixing member and the rotating shaft of the pressure member and a straight line indicating the moving direction of the recording medium in the nip portion ( It is arranged so as to be located on the nip portion outlet side with respect to P2), and the pressing direction in the nip portion is the same as or parallel to the direction of the vertical line passing through the rotation axis of the fixing member. Can do.
Further, when the axial hardness of the fixing member is δF (JIS-A) and the axial hardness of the pressure member is δP (JIS-A), the fixing member and the fixing member The hardness of the pressure member may be selected.
δF <δP <1.2δF …… (1)

The toner applied to the fixing device of the present invention contains a binder resin and a release agent. The toner has a weight average particle diameter (D4) of 2.5 to 5.0 μm and an average circularity of 0. 95-0. 99 is preferred.
In this case, the binder resin may be composed mainly of a polyester resin having a 1/2 outflow temperature of 110 to 145 ° C. in the Koka type flow tester.
The release agent is preferably dispersed in an island shape in the binder resin, and the average dispersed particle size is preferably 0.1 to 1.0 μm.
Further, the release agent is at least one selected from the group consisting of a liberated fatty acid type carnauba wax having an acid value of 5 or less, a montan ester wax, an oxidized rice wax having an acid value of 10 to 30, and a synthetic ester wax. There can be.
Furthermore, the toner may further contain a colorant.

An image forming apparatus according to the present invention includes an image carrier, a charging device that charges the surface of the image carrier, and an exposure device that forms an electrostatic latent image by exposing the charging surface of the image carrier based on image information. A developing device that visualizes the electrostatic latent image as a toner image, a transfer device that transfers the toner image on the image carrier to a recording medium, and the toner image is fixed to the recording medium after the toner image is transferred. In the image forming apparatus including the fixing device, the fixing device is any one of the fixing devices described above.

According to the present invention, the pressure peak in the pressure distribution along the moving direction of the recording medium in the nip portion where the fixing member and the pressure member abut is located closer to the nip portion outlet side than the intermediate point between the nip inlet and outlet. By doing so, the separation property of the recording paper is improved, and inconveniences such as peeling of the coating member on the surface of the separation plate and toner adhesion can be avoided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus to which the present invention is applied. 1, the image forming apparatus includes an image forming apparatus main body 100, a paper feed table 200 on which the image forming apparatus main body 100 is mounted, a scanner 300 attached on the apparatus main body 100, and an automatic document attached on the scanner 300. It is mainly composed of a transfer device (ADF) 400.
In the image forming apparatus main body 100, four image forming means 18 each having an electrophotographic process such as charging, developing, and cleaning are arranged around a photoconductor 40 serving as a latent image carrier. An image forming apparatus 20 is provided. Above the tandem type image forming apparatus 20, there is provided an exposure apparatus 21 that exposes the photoreceptor 40 with laser light based on image information to form a latent image. Further, an intermediate transfer belt 10 made of an endless belt member is provided at a position facing each photoreceptor 40 of the tandem type image forming apparatus 20. A primary transfer unit 62 for transferring the toner images of the respective colors formed on the photoconductor 40 to the intermediate transfer belt 10 is disposed at a position facing the photoconductor 40 via the intermediate transfer belt 10.
A secondary transfer device 22 that collectively transfers the toner images superimposed on the intermediate transfer belt 10 onto transfer paper conveyed from the paper feed table 200 is disposed below the intermediate transfer belt 10. The secondary transfer device 22 is configured by spanning a secondary transfer belt 24 that is an endless belt between two rollers 23, and is disposed so as to press against the support roller 16 via the intermediate transfer belt 10. The toner image on the transfer belt 10 is transferred to transfer paper. Beside the secondary transfer device 22, a fixing device 1 that fixes the image on the transfer paper, which is a feature of the present invention, is provided. The fixing device 1 is configured, for example, by pressing a pressure roller against a fixing belt which is an endless belt. The secondary transfer device 22 described above conveys a transfer sheet after image transfer to the fixing device 1. It has a transport function. Of course, a transfer roller or a non-contact charger may be arranged as the secondary transfer device 22, and in such a case, it is difficult to provide this sheet conveyance function together.
In the illustrated example, a reversing device for reversing the transfer paper in order to record images on both sides of the transfer paper, in parallel with the tandem image forming device 20 described above, under the secondary transfer device 22 and the fixing device 1. 28 is provided.

  For the developing device 4 of the image forming unit 18, a developer containing toner is used. The developing device 4 develops a latent image on the photoconductor 40 by applying an alternating electric field at a position facing the photoconductor 40 at a position facing the photoconductor 40 by the developer carrying body carrying and transporting the developer. By applying the alternating electric field, the developer is activated, the charge amount distribution of the toner can be narrowed, and the developability can be improved.

  The developing device 4 can be a process cartridge that is integrally supported together with the photoreceptor 40 and is detachably formed on the image forming apparatus main body. In addition, the process cartridge may include a charging unit and a cleaning unit.

The operation of the image forming apparatus having such a configuration will be described below.
First, a document is set on the document table 30 of the automatic document feeder 400, or the automatic document feeder 400 is opened and a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed. And hold it.
When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. Immediately drives the scanner 300 to cause the first traveling body 33 and the second traveling body 34 to travel. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

  Also, a start switch (not shown) is pressed, one of the support rollers 14, 15, 16 is rotated by a drive motor (not shown), the other two support rollers are driven to rotate, and the intermediate transfer belt 10 is rotated and conveyed. . At the same time, the photoconductors 40 are rotated by the individual image forming means 18 to form black, yellow, magenta, and cyan monochrome images on the photoconductors 40, respectively. Then, along with the conveyance of the intermediate transfer belt 10, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.

On the other hand, a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller The sheet is separated one by one at 45 and put into the sheet feeding path 46, conveyed by the conveying roller 47, guided to the sheet feeding path 48 in the copying machine main body 100, abutted against the registration roller 49 and stopped.
At this time, the sheet feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. Also good.
Next, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. To record a color image on the sheet.

After the image is transferred, the sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 1, and heat and pressure are applied to the fixing device 1 to fix the transferred image. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and led again to the transfer position, the image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.
On the other hand, residual toner remaining on the intermediate transfer belt 10 after image transfer is removed by the intermediate transfer belt cleaning device 17 to prepare for re-image formation by the tandem image forming device 20.

Hereinafter, the fixing device which is a characteristic part of the present invention will be described in detail with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of the nip portion of the fixing device according to the present invention. In FIG. 2, a nip portion 205 is formed by bringing a fixing roller 201 as a fixing member into contact with a pressure roller 202 as a pressure member, and the fixing roller 201 and the pressure roller 202 are connected to each other. Alternatively, on the cross-sectional view orthogonal to the rotation axis of the pressure roller 201, an intersection P1 of a vertical line passing through the rotation axis of the fixing roller 201 and a straight line 206 indicating the moving direction of the recording paper in the nip portion is the fixing roller. The straight line connecting the rotation axis of 201 and the rotation axis of the pressure roller 202 and the straight line 206 indicating the moving direction of the recording paper in the nip portion are arranged so as to be located on the nip portion outlet side. The pressure direction in the nip portion is the same or parallel to the “vertical direction passing through the rotation axis of the fixing roller 201”. Therefore, the nip direction is apparently inclined downward. In addition, as shown in FIG. 1, the pressure distribution along the recording paper conveyance direction in the nip portion is substantially targeted on both sides of the line connecting the rotation center axes of the fixing roller 201 and the pressure roller 202. The pressure peak, which is the highest pressure point, shifts to the nip outlet side with respect to the intermediate point between the nip inlet and the outlet. That is, in FIG. 2, there is a pressure peak on the vertical direction side of the rotation center axis of the fixing roller 201 with respect to the intermediate point between the entrance and exit of the nip portion.
As described above, by making the pressure on the nip outlet side higher than the pressure on the inlet side, the separation property of the recording paper from the fixing roller or the pressure roller is improved.

That is, according to the present embodiment, the nip outlet side becomes the pressure side, and the moving direction of the recording paper is directed to the pressure side, so that the separation property of the recording paper is improved. As a result, damage to the surface of the separation plate is reduced, and problems such as toner fixation on the separation plate and wear of the fluorine coating or fluororesin tape applied on the separation plate can be eliminated.
In this embodiment, a fixing belt can be used instead of the fixing roller. In this case, instead of the fixing roller and the rotating shaft of the fixing roller, a driving roller or a driven roller of the fixing belt that contacts the pressure roller via the fixing belt and its rotating shaft are applied.

Next, another embodiment of the present invention will be described.
The nip direction can also be set to the pressure side by providing a difference in on-axis hardness between the fixing roller and the pressure roller. In this embodiment, the on-axis hardness of the fixing roller is δF (JIS-A). When the on-axis hardness of the pressure roller is δP (JIS-A), the hardnesses of the fixing roller and the pressure roller are selected so that δF <δP <1.2δF (1) is satisfied. That is, in the present embodiment, the axial hardness δP (JIS-A) of the pressure roller is larger than the axial hardness δF (JIS-A) of the fixing roller, and the axial hardness δF (JIS-A) of the fixing member. ) Less than 1.2 times.
As a result, the nip direction is directed toward the pressure roller, the releasability of the recording paper after image transfer is improved, and the toner adheres to the separation plate and the fluorine coating or fluororesin tape applied on the separation plate is worn. Etc. can be avoided.
If the nip direction is directed too much toward the pressure side, it is conceivable that the recording paper will be wound around the pressure roller side during double-sided paper passing, but by selecting the hardness of the fixing roller and pressure roller within the above range, When the double-sided paper is passed, the recording paper can be prevented from being wound around the pressure roller side and good releasability can be ensured.

Table 1 shows the results of a 64 g paper separation property evaluation test. That is, Table 1 shows the relationship between the axial hardness of the fixing roller and the pressure roller and the peelability of the recording paper during single-sided printing and double-sided printing when 64 g paper is used as the recording paper. is there.

In Table 1, it can be seen that when the hardness of the pressure roller is smaller than the hardness of the fixing roller, the peelability during single-sided printing is poor (Experimental Example 2). On the other hand, when the hardness of the pressure roller is higher than the hardness of the fixing roller, it can be seen that the separability during single-sided printing is good (Experimental Examples 1, 3, and 4).
On the other hand, if the difference in hardness between the fixing roller and the pressure roller is too large, for example, wrapping around the pressure roller side occurs during double-sided printing, resulting in poor peelability (Experimental Example 4).
Therefore, in this embodiment, when the axial hardness of the fixing roller is δF (JIS-A) and the axial hardness of the pressure roller (member) is δP (JIS-A), the following equation 1 is satisfied. And
δF <δP <1.2δF …… (1)
As described above, by selecting the axial hardness of the fixing roller and the pressure roller, the nip direction is directed to the pressure side, the releasability of the recording paper after image transfer is improved, and the separation is performed. Problems such as toner fixation on the plate and abrasion of the fluorine coating or fluororesin tape applied on the separation plate can be avoided.

Next, the toner applied in the present invention will be described.
The toner applied in the present invention is, for example, a toner containing a binder resin, a colorant, and a release agent, and the release agent component is dispersed in islands in the binder resin, and the average of the release agent The dispersed particle size is 0.1 to 1.0 μm.
The amount of the release agent in all the components of the toner depends on the average dispersion diameter of the finely divided release agent, but usually 2 wt% to 10 wt% is appropriate. If the hot offset property is not obtained and the content exceeds 10% by weight, the developability and transferability are deteriorated, and filming on the photosensitive member and the charge imparting member becomes remarkable.

(Measurement of particle size of release agent dispersed by TEM)
In the toner applied to the present invention, the particle size in the maximum direction of the release agent is defined as the release agent dispersion diameter. Specifically, the toner is embedded in an epoxy resin, sliced to about 100 nm, dyed with ruthenium tetroxide, and then observed with a transmission electron microscope (TEM) at a magnification of 10,000 to 50,000 times. The photograph was taken and image evaluation of this photograph was carried out to observe the dispersion state of 50 release agents, and the dispersion diameter was measured and averaged.
As the release agent used for the toner, a low melting point release agent having a melting point of 110 ° C. or less works more effectively as a release agent between the fixing roller or belt and the toner interface, thereby fixing the fixing roller or belt. It is possible to prevent high temperature offset without applying a release material such as oil. If the melting point of the release agent is 110 ° C. or higher, the effect of releasability is not sufficient. Further, if the melting point of the release agent is 30 ° C. or less, the blocking resistance and storage stability of the toner may not be sufficient, which is not preferable. The melting point of the release agent was measured as the maximum endothermic peak by a differential scanning calorimeter (DSC).

In the present invention, the weight average particle diameter (D4) of the toner is 2.5 to 5.0 μm. When the weight average particle diameter of the toner is smaller than 2.5 μm, in the case of a two-component developer, the toner is fused to the surface of the carrier during a long period of stirring in the developing device, and the charging ability of the carrier is lowered, When it is used, toner filming on the developing roller and toner fusion to a member such as a blade for thinning the toner are likely to occur.
On the other hand, when the weight average particle diameter (D4) of the toner is larger than 5.0 μm, the toner layer on the transfer paper becomes non-uniform, the toner releasability is deteriorated, and the transfer paper is not sufficiently separated. There is a case.
Further, as a result of examining the toner shape and the releasability at the time of fixing, in addition to the factor of the toner particle diameter, the average circularity of the toner is 0. 95-0. 99, preferably 0. If it is smaller than 95, the toner layer on the transfer paper becomes non-uniform, the toner releasability is deteriorated, and the transfer paper may be insufficiently separated. If it is greater than 99, the toner is likely to be scattered during transfer, which may cause a problem on the image.

The following materials can be used as a release agent component that functions as a release agent that can be used in the present invention.
Known waxes can be used, and examples thereof include polyolefin waxes (polyethylene wax, polypropylene wax, etc.); long-chain hydrocarbons (paraffin wax, sazol wax, etc.); carbonyl group-containing waxes, and the like. Of these, carbonyl group-containing waxes are preferred. Carbonyl group-containing waxes include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18 -Octadecanediol distearate, etc.); polyalkanol esters (trimellitic acid tristearyl, distearyl maleate, etc.); polyalkanoic acid amides (ethylenediamine dibehenyl amide, etc.); polyalkylamides (trimellitic acid tristearyl amide, etc.) And dialkyl ketones (such as distearyl ketone). Among these carbonyl group-containing waxes, polyalkanoic acid esters are preferred.

The melting point of the wax is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. A wax having a melting point of less than 40 ° C. has an adverse effect on heat-resistant storage stability, and a wax having a melting point of more than 160 ° C. tends to cause a cold offset during fixing at a low temperature. Further, the melt viscosity of the wax is preferably 5 to 1000 cps, more preferably 10 to 100 cps, as a measured value at a temperature 20 ° C. higher than the melting point. Waxes exceeding 1000 cps are poor in improving hot offset resistance and low temperature fixability. The content of the wax in the toner is usually 0 to 40% by weight, preferably 3 to 30% by weight.

In addition, as the binder resin used in the toner applied in the present invention, one having the following composition can be used as long as the characteristics of the toner are satisfied.
For example, homopolymers of styrene such as polyester, polystyrene, poly p-chlorostyrene, polyvinyltoluene and the like; and styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers. Styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate Copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, Styrene-vinyl ethyl acetate Ter copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Examples thereof include styrene copolymers such as copolymers.

It is presumed that the fixing to the paper in the roller fixing or the belt fixing starts at around 70 ° C. to 100 ° C. in the copying machine, printer, FAX, etc., in which the toner fixing effective temperature is recent energy saving. In order to allow the toner to melt, the toner must start to flow around this temperature. Therefore, the toner must be softened at least at about 90 to 110 ° C. and fixing must be started.
However, in order to soften at 90 ° C., the glass transition must be 50 ° C. or lower, and the Tg (glass transition point) of such a polymer is also related to the molecular weight. Usually, when the glass transition point is 50 ° C. or lower, the fixability is good, but the storage stability is not satisfied.

  In addition, known dyes and pigments can be used as toner colorants, such as carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, Yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthracene Yellow BGL, Isoindolinone Yellow, Bengala, Red Tan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Parared, Phi Sae Red, Paraku Luort Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carnmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Tolujing Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, thioindigo red B, thioindigo maroon, oil red, quinacridone red, pi Zoron Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indance Ren Blue (RS, BC), Indigo, Ultramarine Blue, Bituminous Blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chrome Oxide, Pyridian, Emerald Green , Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Gree Lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, lithopone and mixtures thereof can be used. The content of the colorant is usually 1 to 15 wt%, preferably 3 to 10 wt%, based on the toner.

  The colorant can also be used as a master batch combined with a resin. As the binder resin to be kneaded together with the production of the master batch or the master batch, in addition to the above-mentioned modified and unmodified polyester resins, styrene such as polystyrene, poly p-chlorostyrene, and polyvinyl toluene, and polymers of substituted products thereof; Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α- Chloromethyl methacrylate copolymer, Tylene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid Styrene copolymers such as acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, poly Acrylic resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin paraffin wax, etc. wear.

  A masterbatch can be obtained by mixing and kneading a resin for a masterbatch and a colorant under a high shearing force. At this time, an organic solvent can be used in order to enhance the interaction between the colorant and the resin. In addition, a so-called flushing method called an aqueous paste containing water of a colorant is mixed and kneaded together with a resin and an organic solvent, and the colorant is transferred to the resin side to remove moisture and organic solvent components. Since the cake can be used as it is, it does not need to be dried and is preferably used. For mixing and kneading, a high shear dispersion device such as a three-roll mill is preferably used.

The toner applied to the present invention may contain a charge control substance as necessary. In particular, a high charge amount can be imparted by fixing the charge control substance to the surface of the toner. That is, by fixing the charge control substance to the surface of the toner, the amount and state of presence on the toner surface are stabilized, and the charge amount can be stabilized. In particular, in the toner having the configuration of the present invention, the charge amount stability is increased.
As the charge control substance, all known substances can be used. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified) Quaternary ammonium salts), alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives.
Specifically, Nitronine-based dye Bontron 03, quaternary ammonium salt Bontron P-51, metal-containing azo dye Bontron S-34, oxynaphthoic acid metal complex E-82, salicylic acid metal complex E- 84, E-89 of a phenol-based condensate (manufactured by Orient Chemical Industry Co., Ltd.), TP-302 of a quaternary ammonium salt molybdenum complex, TP-415 (manufactured by Hodogaya Chemical Co., Ltd.), quaternary ammonium Copy charge PSY VP2038 of salt, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit), copper phthalocyanine, perylene Quinacridone, azo pigment, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as a quaternary ammonium salt.

In the present invention, the amount of charge control agent used is determined uniquely by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is uniquely limited. However, preferably, 0. It is used in the range of 1 to 10 parts by weight. Preferably, 0. A range of 2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the main charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the flowability of the developer is reduced, and the image density is reduced. Incurs a decline. Further, a fluidity improver used for the purpose of improving the fluidity of the toner may be used. Specifically, silica, titanium oxide, alumina and the like are preferable, and silica subjected to hydrophobic treatment is particularly preferable.

Such a fluidizing agent can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having a fluoroalkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. . Further, in order to remove the developer after transfer remaining on the photosensitive member or the primary transfer medium, a cleaning property improver may be included. Examples of the cleaning property improver include zinc stearate, calcium stearate, stearic acid, and the like. Examples thereof include fatty acid metal salts such as polymer fine particles produced by soap-free emulsion polymerization such as polymethyl methacrylate fine particles and polystyrene fine particles.
The fine polymer particles have a relatively narrow particle size distribution and an average particle size of 0. The thing of 01-1 micrometer is preferable.

(Developer)
When the toner of the present invention is used for a two-component developer, it may be used by mixing with a magnetic carrier, and the content ratio of the carrier and the toner in the developer is 1 to 10 weights of toner with respect to 100 parts by weight of the carrier. Part is preferred.
As the magnetic carrier, conventionally known ones such as iron powder, ferrite powder, magnetite powder and magnetic resin carrier having a particle diameter of about 20 to 100 μm can be used.
The carrier may be coated with a resin, and examples of the coating material include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Polyvinyl and polyvinylidene resins such as acrylic resins, polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins and styrene-acrylic copolymer resins, Halogenated olefin resin such as vinyl chloride, polyester resin such as polyethylene terephthalate resin and polybutylene terephthalate resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexa Fluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, tetrafluoroethylene and vinylidene fluoride Fluoro such as terpolymers of emission and non-fluoride monomers including, and silicone resins.

Moreover, you may contain electrically conductive powder etc. in coating resin as needed. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide or the like can be used. These conductive powders preferably have an average particle diameter of 1 μm or less. When the average particle diameter is larger than 1 μm, it becomes difficult to control the electric resistance.
The toner of the present invention can also be used as a one-component magnetic toner that does not use a carrier or a non-magnetic toner.
The toner used in the present invention particularly contains at least a binder resin and a release agent, and the binder resin is a polyester having a 1/2 outflow temperature of 110 to 145 ° C. (claim 6) in the Koka type flow tester. Resin as a main component, and the release agent was selected from the group consisting of a desorbed fatty acid type carnauba wax having an acid value of 5 or less, a montan ester wax, an oxidized rice wax having an acid value of 10 to 30, and a synthetic ester wax. Contains at least one.

By using as a main component a polyester resin having a 1/2 outflow temperature of 110 to 145 [deg.] C. as a toner binder resin applied to a belt type fixing device, sufficient fixing performance and sufficient Excellent offset resistance.
Further, the release agent used in the present invention exhibits an appropriate dispersibility in the polyester resin, and exhibits a sufficient release property at the time of fixing. In other words, the release agent is compatible with the polyester resin, and sufficient release of the release agent cannot be obtained at the time of fixing, and the release property is not deteriorated. In other words, the toner does not exist in the toner, and the phenomenon that stable releasability at the time of fixing cannot be obtained does not occur.
When the ½ outflow temperature is less than 110 ° C., the toner blocking property is deteriorated and the offset property may be deteriorated. When the ½ outflow temperature is higher than 145 ° C., the toner fixing property is not good. May be sufficient.

In the present invention, a polyester resin is preferably used as the binder resin. Above all, when a polyester resin synthesized from a monomer mainly composed of bisphenol alcohol and a polycarboxylic acid is used, A good toner can be obtained without impairing the color of the colorant of the color and color toner. In addition, the fixing property at a low temperature is improved.
The polyester resin is obtained by condensation polymerization of an alcohol and a carboxylic acid. Examples of the alcohol used include ethylene glycol, diethylene glycol, triethylene glycol, and 1,2-propylene glycol. Diols such as 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,4-bis (hydroxymethyl) cyclohexane And etherified bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A, and other divalent alcohols A monomer can be mentioned. Examples of the carboxylic acid include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, Examples include malonic acid, inorganic substances of these acids, dimers of lower alkyl esters and linolenic acid, and other divalent organic acid monomers. It is also preferable to use not only a polymer composed of only the above bifunctional monomer but also a polymer containing a component composed of a trifunctional or higher polyfunctional monomer. Examples of such a polyfunctional monomer that is a trihydric or higher polyhydric alcohol monomer include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, and dipentaerythritol. , Tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methylpropanetriol, 2-methyl-1,2,4-butane Examples include triol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like.

Examples of the trivalent or higher polyvalent carboxylic acid monomer include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, and 2,5. , 7-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-digalboxyl-2-methyl-2-methylene Examples thereof include carboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, embole trimer acid and acid anhydrides thereof.
It is desirable that the above-described component composed of a trifunctional or higher polyfunctional monomer is contained in a proportion of 30 to 80 mol% in each of the alcohol component or acid component as a structural unit in the polymer.

The polyester resin can be prepared, for example, by polycondensing a polyol component and a polyvalent carboxylic acid component at a temperature of 180 to 250 ° C. in an inert gas atmosphere.
Moreover, 1/2 outflow temperature is the value calculated | required by Shimadzu Corporation Koka type | mold flotester-CFT-500. The measurement conditions were a load of 20 kg, a die diameter of 1.0 mm, a heating rate of 3 ° C./min, and the temperature at which the sample flowed out by half.
In addition, the free fatty acid type carnauba wax as a release agent used in the toner of the present invention is obtained by removing free fatty acid from carnauba wax, and the acid value is 5% or less, and It becomes finer than the conventional carnauba wax, and the dispersed particle size in the binder resin becomes 1 μm or less, thereby improving dispersibility.
It has been found that the use of the toner having these toner characteristics improves the separation performance and increases the separation margin at the front end position of the separation plate.

By using the above toner, the toner layer on the transfer paper is made uniform, the releasability of the toner is further improved, the transfer paper is improved in separation property, the wrapping of the transfer paper is improved, and an appropriate amount of separation is achieved at the time of fixing. The mold oozes out on the toner surface and the offset resistance is improved.
In other words, by using a toner resin whose main component is a polyester resin having a 1/2 outflow temperature of 110 to 145 ° C. in the Koka flow tester, excellent fixability and sufficient offset resistance are obtained. . Further, by applying the toner, sufficient releasability is exhibited at the time of fixing. That is, the release agent is compatible with the polyester resin, and sufficient release of the release agent is obtained at the time of fixing, so that deterioration of the release property can be prevented. It should be noted that due to poor dispersion in the polyester resin, there is no occurrence of a phenomenon in which the toner does not exist in the toner and stable releasability upon fixing cannot be obtained.

1 is a schematic configuration diagram of an image forming apparatus to which a fixing device of the present invention is applied. FIG. 4 is an explanatory view showing a nip portion of the fixing device according to the present invention. It is explanatory drawing of a prior art. It is explanatory drawing of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing device 4 Developing device 10 Intermediate transfer belt 14, 15, 16 Support roller 18 Image forming means 20 Tandem type image forming device 21 Exposure device 22 Secondary transfer device 23 Roller 24 Secondary transfer belt 30 Document table 32 Contact glass 33 One traveling body 34 Second traveling body 35 Imaging lens 36 Capture sensor 40 Photoconductor 42 Paper feed roller 43 Paper bank 44 Paper feed cassette 45 Separating roller 46 Paper feed path 47 Carriage roller 48 Paper feed path 49 Registration roller 50 Paper feed roller 51 Manual feed tray 52 Separating roller 53 Manual feed path 55 Switching claw 57 Paper discharge tray 62 Primary transfer means 100 Image forming apparatus main body 200 Paper feed table 201 Fixing roller 202 Pressure roller 203 Separating plate 204 Arrow 205 indicating the pressure direction Nip Part 206 A straight line (arrow) indicating the recording paper moving direction
300 Scanner 301 Driving roller 302 Pressure roller 303 Fixing belt 304 Driven roller 305 Separating plate 306 Nip 307 Arrow indicating pressure direction 308 Arrow indicating recording paper moving direction 400 Automatic document feeder (ADF)
401 Fixing roller 402 Pressure roller 403 Separating plate 404 Arrow indicating the pressing direction 405 Nip portion 406 Arrow indicating the recording paper moving direction

Claims (9)

A fixing member and a pressure member that form a nip portion, and a recording medium that is arranged in a non-contact manner with respect to the fixing member and the pressure member and has a toner image fixed through the nip portion are added to the fixing member or the addition member. In a fixing device including a separation plate that is separated from the pressure member,
The fixing device, wherein the maximum value of the pressure distribution along the moving direction of the recording medium in the nip portion is present on the nip portion outlet side with respect to an intermediate point between the inlet and outlet of the nip portion.   The fixing member and the pressure member indicate a vertical line passing through the rotation axis of the fixing member and a moving direction of the recording medium in the nip portion on a cross-sectional view orthogonal to the rotation axis of the fixing member or the pressure member. The intersection (P1) with the straight line is more than the intersection (P2) between the straight line connecting the rotation axis of the fixing member and the rotation axis of the pressure member and the straight line indicating the moving direction of the recording medium in the nip portion. The pressure direction in the nip portion is the same as or parallel to the direction of the vertical line passing through the rotation axis of the fixing member. The fixing device according to 1. When the on-axis hardness of the fixing member is δF (JIS-A) and the on-axis hardness of the pressing member is δP (JIS-A), the fixing member and the pressure are set so that the following formula (1) is satisfied. The fixing device according to claim 1, wherein the hardness of the member is selected.
δF <δP <1.2δF …… (1)   The toner for forming the toner image contains a binder resin and a release agent. The toner has a weight average particle diameter (D4) of 2.5 to 5.0 μm and an average circularity of 0. 95-0. The fixing device according to claim 1, wherein the fixing device is 99.   5. The fixing device according to claim 4, wherein the binder resin is mainly composed of a polyester resin having a 1/2 outflow temperature of 110 to 145 ° C. in a Koka type flow tester.   The fixing device according to claim 4, wherein the release agent is dispersed in an island shape in the binder resin, and an average dispersed particle diameter is 0.1 to 1.0 μm.   The release agent is at least one selected from the group consisting of a desorbed fatty acid type carnauba wax having an acid value of 5 or less, a montan ester wax, an oxidized rice wax having an acid value of 10 to 30, and a synthetic ester wax. The fixing device according to claim 4, wherein   The image forming apparatus according to claim 4, wherein the toner further contains a colorant. An image carrier, a charging device for charging the surface of the image carrier, an exposure device for exposing the charged surface of the image carrier based on image information to form an electrostatic latent image, and the electrostatic latent image An image having a developing device that visualizes a toner image, a transfer device that transfers the toner image on the image carrier to a recording medium, and a fixing device that fixes the toner image on the recording medium after the toner image is transferred. In the forming device,
The image forming apparatus according to claim 1, wherein the fixing device is the fixing device according to claim 1.

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