JPH11237759A - Developer and image forming device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good image at a low cost by using a developer which is good in offset resistance, flow property and preservable property and is small in spent amt. SOLUTION: Wax which consists essentially of an ester component having a peak of a carbon number distribution at a carbon number 40 to 100 and in which the peak of the carbon number distribution of its acid component occupies >=60% of the acid component of the entire part, is added to a binder resin at 0.1 to 15 wt.% of the total weight of the resin. As a result, the developer which makes it possible to obtain the good image and has the good offset resistance, flow property and preservable property and is small in the spent amt. is obtd. In addition, an oil coating mechanism for heat rollers, etc., may be simplified by using such developer. The image forming device which makes it possible to reduce the device cost and printing cost and to form the good image without the occurrence of the wear of the heat roller is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus using electrophotographic technology and a developer used for the apparatus.

[0002]

2. Description of the Related Art In the electrophotographic technique, an electrostatic latent image forming step for forming an electrostatic latent image on a photoreceptor is usually performed, and this electrostatic latent image is developed using a developer to form a developer image. Image formation is performed by a development step, a transfer step of transferring a developer image onto a transfer material such as paper, and a fixing step of fixing the transferred developer image.

In the fixing step, a developer image is generally thermocompression-bonded to a transfer material using a heated heat roller. At the time of heat fixing by the heat roller, the developer is not fixed to the transfer material, and an offset phenomenon that adheres to the heat roller is likely to occur. For this reason, conventionally, the offset phenomenon has been prevented by adding a wax to the developer to improve the releasability of the developer from the heat roller.

[0004] As such a wax, a method of adding a natural wax or a polyolefin wax having sharp melting properties has been proposed. However, the effect of preventing offset varies depending on the type of wax, and depending on the type of wax, there are problems such as significantly deteriorating the fluidity and preservability of the obtained developer and causing spent on the developer. there were.

[0005] In a full-color electrophotographic apparatus, a sharp melt resin which is easy to melt is usually used in order to reproduce colors by color superposition. Therefore, high-temperature offset is more likely to occur as compared with general monochrome electrophotographic toner. In order to solve the problem, a method of applying a large amount of silicone oil to a heat fixing roller having a rubber surface has conventionally been used.

FIG. 8 is a schematic diagram for explaining an example of a fixing device used in a conventional full-color image forming apparatus. As shown in the figure, this apparatus is provided opposite to the heat roller 1, a cleaning roller 4 provided on the heat roller 1, a means for supplying silicon oil to the heat roller 1, and the heat roller 1. It has a pressure roller 2 that can rotate in synchronization with the heat roller 1.
The means for supplying the silicon oil includes an oil application roller 101 which can rotate in synchronization with the heat roller 1, an oil impregnation tank 8 having an oil impregnation roller 9 which can rotate in synchronization with the oil application roller 101, an oil impregnation. An oil transfer pipe 7 having an oil transfer pump 6 connected to the tank 8; an oil supply tank 5 connected to the oil transfer pipe 7 and containing silicone oil; an oil recovery filter 102 provided below the pressure roller; There is an oil transport pipe 103 connecting between the recovery filter 102 and the oil supply tank 5.

In this fixing device, the silicone oil supplied from the oil supply tank 5 is applied to the oil application roller 1.
01, it is possible to apply a large amount on the heat roller 1.

However, this method requires a complicated oil application mechanism as described above, and causes the heat roller to wear due to the mechanical stress of the oil application mechanism, thereby shortening the life of the heat roller. there were.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to provide offset resistance,
An object of the present invention is to provide a developer having good fluidity and preservability and having a small amount of spent.

[0010] Also. Another object of the present invention is to use a developer having good offset resistance, fluidity and preservability, and a small amount of spent, thereby simplifying an oil application mechanism of a heat roller and reducing wear of the heat roller. It is an object of the present invention to provide a low-cost image forming apparatus which does not cause a problem.

[0011]

The developer of the present invention comprises a binder resin, a colorant, and an ester component having a peak of carbon number distribution in the range of 40 to 100 carbon atoms. The peak of the number distribution accounts for 60% or more of the total acid component, and its content is 0.1 to 15% based on the total weight of the binder resin.
% By weight of wax.

An image forming apparatus according to the present invention comprises an image carrier, a binder resin, a colorant, and an ester component having a carbon number distribution peak at 40 to 100 carbon atoms provided on the image carrier. As the main component, the peak of the carbon number distribution of the acid component is
A developer containing a wax occupying 60% or more of the entire acid component and having a content of 0.1 to 15% by weight based on the total weight of the binder resin is contained and formed on the surface of the image bearing member. A developing device for visualizing the electrostatic latent image with the developer to form a developer image, a transfer device for transferring the developer image to a material to be transferred, and a transfer device for transferring the transferred developer image. And a fixing device for fixing to the transfer material.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has investigated the characteristics of various waxes that can be used in a developer, and has found that the offset resistance is good, good fluidity and storage stability are maintained, and the spent toner is used. The present inventors have found a wax that is effective for preventing the occurrence of the odor, and have accomplished the present invention.

The developer of the present invention contains a binder resin, a coloring material, and a wax, and the wax used has a carbon number of 40.
The main component is an ester component having a peak of carbon number distribution at ~ 100, and the peak of carbon number distribution of the acid component occupies 60% or more of the entire acid component, and the content is based on the total weight of the binder resin. On the other hand, the content is 0.1 to 15% by weight.

Further, the image forming apparatus according to the present invention forms an image carrier and an electrostatic latent image formed on the image carrier and visualized by a developer to form a developer image. And a transfer device for transferring the developer image to the transfer material, and a fixing device for fixing the transferred developer image to the transfer material. The developer
A binder resin, a colorant, and an ester component having a carbon number distribution peak at 40 to 100 carbon atoms as a main component, and the peak of the carbon number distribution of the acid component accounts for 60% or more of the entire acid component. The content is 0.1 to the total weight of the binder resin
And 15% by weight of wax.

The present inventors prepared a developer using various waxes, and examined the toner properties such as offset property, fluidity, storage property, and spent amount. 1) Melting Point of Wax and Toner Characteristics The inventors first prepared a developer using waxes having various melting points, and examined the toner characteristics. An example is shown below.

Preparation of Samples 1 to 5 An azo pigment 3% and a metal complex C were added to a polyester resin.
After kneading 1% of CA and 5% of wax, volume average particle size 8μm
To obtain a toner to which 1% of silica having an average particle diameter of 16 nm was added.

Table 1 below shows a comparison of toner characteristics depending on the type of wax. In addition, the offset property was investigated as follows. First, an image is fixed with a nip width of 7 mm by controlling the temperature to 160 ° C. using a heat roll fixing device in which dimethyl silicone oil (300CS) is applied to an elastic rubber roller. After fixing, the white paper is passed through, the amount of toner adhering to the white paper is observed, the degree of offset is determined, and those in which the adhered toner is not visually observed are indicated by double circles. Those that did not hinder the formation were evaluated as 、, those that hindered the image formation due to the attached toner were evaluated as Δ, and those that wrapped the recording paper around the fixing roller due to offset were evaluated as x.

The fluidity was measured by measuring the remaining amount (g) of the toner on the mesh after 20 g of the toner was shaken with the mesh. The smaller the number, the better the fluidity. The storage stability was determined by measuring the remaining amount (g) of the toner on the mesh after shaking 20 g of the toner left at 55 ° C. for 8 hours with a mesh. The smaller the number, the better the preservability.

The amount of spent was determined by separating the carrier from the developer after printing 5,000 sheets, measuring the amount of carbon, and determining the difference from the amount of carbon in the initial carrier. The smaller the number, the less the amount of spent.

[0021]

[Table 1]

From the above Table 1, it was found that a wax having a too low melting point markedly deteriorates fluidity and storage stability. Further, it was found that a wax having a too high melting point could not obtain a sufficient offset prevention effect. From these results, it was found that the wax having a melting point in the range of 70 to 90 ° C. was good.

2) Components of Wax and Characteristics of Toner Next, experiments similar to those in Table 1 were conducted for various waxes having melting points in the range of 70 to 90 ° C. Table 2 below shows the types of wax and the toner characteristics for one example.

[0024]

[Table 2]

As shown in Table 2 above, samples 3, 6,
8, it can be seen that good results are obtained for the offset. Samples 3 and 6 are synthetic ester waxes.

The rice wax of Sample 8 is a natural wax containing an ester component as a main component, and the best results were obtained in all of the offset resistance, fluidity, and spent amount.

From the above, it is considered that a wax containing an ester component as a main component is effective in preventing offset.
However, in Table 2, rice waxes A and B,
Carnauba No. In No. 1, a difference was found in the offset properties, though all contained an ester component as a main component. From these facts, rice waxes A and B, carnauba No. 1
Was considered further.

3) Carbon number distribution of wax Rice wax A, B, carnauba no. In order to further consider No. 1, the carbon number distribution of the acids and alcohols of these three waxes was examined. The results are shown in Table 3 below.

[0029]

[Table 3]

As shown in Table 3 above, the carnauba wax has a very wide distribution of the carbon content of the acid component. Rice wax A has a C24 acid component of 55.
8%. On the other hand, the C24 acid component of rice wax B having the best toner characteristics is 6% of the total acid component.
It accounts for 3.8%.

The synthetic ester wax used in Samples 3 and 6 uses behenic acid (C22) having a purity of 80% or more as an acid component. Synthetic ester wax A is C2
Esterification of a monovalent fatty acid of 2 and a monohydric alcohol of C22 results in one molecule of C44. The synthetic ester wax B is obtained by esterifying a C22 monovalent fatty acid and a C5 tetravalent alcohol, and one molecule is C93.

From the above results, an ester component having a carbon number distribution peak at 40 to 100 carbon atoms as a main component,
Further, it was found that when a wax having a peak of the carbon number distribution of the acid component occupying 60% or more of the entire acid component was used, good offset properties could be obtained.

A preferred wax is a synthetic ester wax of behenic acid and alcohol, or a rice wax having a carbon number distribution peak of an acid component of a fatty acid having 24 carbon atoms.
It was found to be rice wax in fatty acids.

FIGS. 1 to 4 show DSC curves of rice waxes A and B, carnauba wax and synthetic ester wax A, respectively. Rice wax B and synthetic ester waxes A and B have very sharp endotherms as compared with rice wax A and carnauba wax. For this reason, it is considered that a wax having a sharp carbon number distribution of the ester component has a sharp endotherm. If the endothermic characteristics are not sharp, it is considered that components that melt at low temperatures cause deterioration in storage stability, fluidity, and spent, and components that melt at high temperatures hinder improvement in offset properties. Therefore, it is considered that good results were obtained with wax having a sharp endothermic characteristic.

The amount of the wax added is 0.1 to 15% by weight based on the total weight of the binder resin. If the amount is less than 0.1% by weight, a sufficient releasing effect cannot be obtained, and %, The wax contaminates the carrier, so that the charging characteristics deteriorate and the image tends to deteriorate.

Next, an example of the image forming apparatus of the present invention will be described with reference to FIG. In FIG. 5, a photosensitive drum 11 serving as an image carrier is a cylindrical laminated organic photosensitive member having a diameter of 40 mm and a length of 266 mm, and is provided so as to be rotatable in the direction of the arrow shown in the figure.

The following are arranged around the photosensitive drum 11 along the rotation direction. That is, an exposure unit 15 that exposes the surface of the photoconductor drum 11 charged by a charging roller (not shown) to form an electrostatic latent image, and a developer is stored downstream of the exposure unit 15. A developing device 12 for developing the formed electrostatic latent image and a means 14 for transporting a sheet as a transfer material to the photosensitive drum 21 are provided downstream of the developing device 12.

Further, a blade cleaning device 13 and a static elimination lamp (not shown) are provided downstream of the contact position of the photosensitive drum 11 with the sheet. Conveying means 1
Reference numeral 4 has a width substantially equal to the width of the photosensitive drum 11. The transporting means 14 is in the form of an annular belt, and the upstream and downstream annular portions of the transporting means 14 are respectively provided with a tension roller 17 and a driving roller 1.
8 are provided. The conveying means 14 moves the tension roller 17 and the driving roller 18 so as to follow the outer periphery of the tension roller 17 and the driving roller 18 in this annular portion.
Is in contact with The distance from the tension roller 17 to the drive roller 18 is about 300 mm.

Tension roller 17 and drive roller 18
Are provided so as to be rotatable in the directions indicated by arrows. With the rotation of the driving roller 18, the conveying means 14 is sent in a ring shape. The transport speed is controlled to synchronize with the rotation speed of the photoconductor.

The above-described photoreceptor drum 11, exposure unit 15, developing unit 12, blade cleaning device 13, and discharge lamp 16 constitute a process unit 100.

On the transport means 14, the tension roller 1
A process unit 100, a process unit 200, a process unit 300, and a process unit 400 are provided between the drive unit 7 and the drive roller 18 along the transport direction.
0, the process unit 400 has the same configuration as the process unit 100.

That is, the photosensitive drum 1, the photosensitive drum 21, the photosensitive drum 31, and the photosensitive drum 41 are provided substantially at the center of each process unit. Around the photosensitive drum, an exposure unit 25, an exposure unit 3
5, and an exposure unit 45; downstream of the developing unit 22, the developing unit 32, and the developing unit 42;
3, the configuration provided with the blade cleaning device 33 and the blade cleaning device 43
Same as 0.

A different structure in each process unit is a developer housed in a developing device. For example, the developing device 12
, Yellow for the developing unit 22, cyan for the developing unit 32, and black for the developing unit 42.
As a main component, a binder resin and an ester component having a carbon number distribution peak at 40 to 100 carbon atoms, and the peak of the carbon number distribution of the acid component accounts for 60% or more of the entire acid component,
The content is 0.1 to 15% by weight based on the total weight of the binder resin.
And a developer containing wax.

When a color image is output, the sheets conveyed by the conveying means 14 are photosensitive drums 1, 21, 31, 41, respectively.
And contact sequentially. This paper and each photosensitive drum 11,
Power supply rollers 19, 29, 39, and 49, which are transfer units, are provided in a one-to-one correspondence with the photoconductor drums 11, 21, 31, and 41 at contact positions with 21, 31, and 41. ing.

That is, the power supply rollers 19, 29, 39, 4
Reference numeral 9 denotes a contact position with the corresponding photoconductor drum 11, which is provided in back contact with the conveying means 14, and is opposed to the photoconductor drum 11 via the conveying means 14. The power supply rollers 19, 29, 39, and 49 are connected to a bias power supply (not shown). Power supply rollers 19, 2
Reference numerals 9, 39, and 49 are adapted to rotate following the movement of the transport means 14.

Here, the image forming process of the image forming apparatus thus configured will be described. The rotating photosensitive drums 11 and 12 of each of the above four process units
1, 31, 41 are uniformly charged to 50 V by a charging unit (not shown) to which an AD superimposed DC bias is applied.

Photoreceptor drums 11 and 12 uniformly charged
Exposure units 1, 31 and 41 perform exposure with a phosphor.
Light is irradiated from 5, 25, 35, and 45 to form an electrostatic latent image. Developing devices 12, 22, 3
The development is carried out by the developers 2 and 42 which are sufficiently charged in advance for each color.

On the other hand, the paper is sent from a paper feed cassette (not shown) to a transfer position of the photosensitive drum 11. When the sheet is conveyed to the transfer position, a voltage of, for example, about 1400 V is applied to the conveying means 14 from the power supply rollers 19, 29, 39, and 49 as a bias voltage. By applying a bias voltage, the photosensitive drums 11, 21, 3
A transfer electric field is formed between the transfer means 14 and the transfer means 14. Therefore, first, the developer image on the photosensitive drum 11 is transferred to a sheet, and the sheet carrying this developer image is conveyed and reaches the photosensitive drum 21. The developer image formed on the photosensitive drum 21 is transferred to be superimposed on the previously transferred developer image. The sheet is further conveyed, and the developer images of the respective colors are similarly transferred onto the photosensitive drums 31 and 41.

As described above, the sheet carrying the image formed by the multiple transfer is sent from the conveying means 14 to the fixing device 15. The fixing device 15 has a heat roller 35 and a pressure roller 45. The sheet is fixed on the sheet by passing the image between the heat roller and the pressure roller in a state where the image contacts the heat roller.

In the above-described full-color electrophotographic apparatus, a sharp-melt resin which is easy to melt is used in order to reproduce colors by color superposition. Therefore, high-temperature offset is more likely to occur as compared with general monochrome electrophotographic toner. Since the toner according to the present invention has very good offset resistance, even when used in a full-color electrophotographic apparatus, the spent amount is small, its fluidity, preservability, and offset resistance are good, and An image is obtained.

Further, in the full-color electrophotographic apparatus, a method of applying a large amount of silicone oil to the roller surface of the fixing device has been used to eliminate the offset. There is no need to use such a method. Therefore, the image forming apparatus of the present invention does not require such a complicated oil application mechanism for applying the silicone oil, and can simplify the fixing device. Further, since the mechanical stress due to the oil application mechanism is eliminated, the wear of the heat roller is remarkably reduced, and as a result, the life of the heat roller can be extended.

Further, by coating the surface of the heat roller with a fluorine-containing resin, the mechanical strength of the roller can be increased. Conventionally, when coating with a fluorine-containing resin, it was difficult to apply the oil sufficiently evenly because the roller surface became difficult to wet, and it could not be used in combination with a full-color toner. By using the toner according to the present invention, offset can be prevented even if oil application is not sufficiently performed. For this reason, it becomes possible to use in combination with a fluorine-containing resin-coated roller. in this way. By combining the toner according to the present invention with the fluororesin-coated roller, it is possible to further extend the life of the fixing roller.

The types of fluorine-containing resin include PFA (ethylene tetrafluoride-perfluorovinyl ether copolymer),
And PTFE. Examples of the binder resin usable in the present invention include styrene-based copolymers such as polystyrene, styrene, butadiene copolymer, and styrene-acryl copolymer, polyethylene, polyethylene acetate copolymer, and polyethylene vinyl alcohol. Copolymers, phenolic resins, epoxy resins, allyl phthalate resin polyamide resins, maleic acid resins, and the like. Particularly, a sharp melt resin such as polyester is more preferably used for forming a color image. Examples of the coloring material that can be used in the present invention include, for example, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, methylene blue, dupon oil red, methylene blue chloride, malachite green, oxalate, lamp black, and rose beregal. In addition to these and mixtures thereof, various dyes and pigments can be used.

The binder resin is used in an amount of 70 to 70% based on the total weight of the developer.
It is preferable that 98% by weight and 1 to 8% by weight of the coloring material are contained. 6 and 7 show other examples of the image forming apparatus of the present invention.

In the image forming apparatus shown in FIG. 6, four types of developing devices 11 each containing four colors of developer similar to those used in the apparatus shown in FIG.
2, 122, 132, and 142 are integrally formed so as to be rotatable and movable, and a transfer roller 54, a cleaning device 53, and a charge removing device 56 are provided downstream of the developing device. A fixing device 15 including a heat roller 35 and a pressure roller 45 is provided downstream. In this apparatus, first, a developing device 112 develops an electrostatic latent image on a common photosensitive drum 51, and the obtained developer image is conveyed to a transfer position between the transfer roller 54 and the photosensitive drum 51. Transfer to paper. Thereafter, the photosensitive drum 51 is cleaned by the cleaning device 53, and the charge is removed by the charge removing device 56, thereby completing one cycle of transfer. Next, development is performed by the developing device 122, and a similar transfer operation is performed. Further, the developing units 132 and 142 perform similar development and transfer. The developer image multi-transferred onto the sheet in this manner is fixed in the same manner as in the apparatus shown in FIG.

The image forming apparatus shown in FIG. 7 is a modification of the image forming apparatus shown in FIG. 6, in which an intermediate transfer roller 64 is provided instead of the transfer roller 54 so as to face the photosensitive drum 51. In this apparatus, the developer image on the photosensitive drum 51 developed by the developing device 112 is temporarily transferred to the surface of the intermediate transfer roller 64. Then, the photosensitive drum 5
1 is cleaned by the cleaning device 53, the charge is removed by the charge removing device 56, and one cycle of transfer is completed. Next, development is performed by the developing device 122, and the image is similarly transferred onto the intermediate transfer roller 64. Similar development and transfer operations are performed for the developing devices 132 and 142. The developer image multiplex-transferred onto the surface of the intermediate transfer roller 64 in this manner is then transferred onto the sheet by bringing the sheet into contact with the intermediate transfer roller 64. The developer image transferred onto the paper is fixed in the same manner as in the apparatus shown in FIG.

In the apparatus shown in FIGS. 6 and 7,
As in the apparatus shown in (1), a high-quality image can be obtained by using a developer having a small amount of spent and having good offset resistance, fluidity and storage stability. Further, in particular, the developer according to the present invention has a good offset resistance even when using a sharp melt resin which is easy to melt. Has the effect of extending the life.

[0058]

According to the present invention, a good image can be obtained,
A developer having good offset resistance, fluidity and storage stability and a small amount of spent can be obtained. Further, by using such a developer, the oil application mechanism of the heat roller can be simplified, the apparatus cost and the printing cost can be reduced without causing wear of the heat roller, and a good image can be formed. The resulting image forming apparatus is obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a DSC curve of wax.

FIG. 2 is a graph showing a DSC curve of wax.

FIG. 3 is a graph showing a DSC curve of wax.

FIG. 4 is a graph showing a DSC curve of wax.

FIG. 5 shows an example of the image forming apparatus of the present invention.

FIG. 6 shows another example of the image forming apparatus of the present invention.

FIG. 7 shows still another example of the image forming apparatus of the present invention.

FIG. 8 is a schematic diagram illustrating an example of a fixing device used in a conventional full-color image forming apparatus.

[Description of sign]

1, 35: Heat roller 2, 45: Pressure roller 11, 21, 31, 41, 51: Photoconductor drum 12, 22, 32, 42, 112, 122, 132, 1
42 developing device 13,23,33,43 cleaning device 14 conveying means 15 fixing device 16,26,36,46 discharging lamp 17 tension roller 18 drive roller 54 transfer roller 64 intermediate transfer roller 100 , 200,300,400 ... Process unit

Claims (7)

[Claims] 1. A binder resin, a coloring material, and a carbon number of 40 to 1.
The ester component having a carbon number distribution peak at 00 as a main component, the peak of the carbon number distribution of the acid component accounts for 60% or more of the entire acid component, and the content is 0% with respect to the total weight of the binder resin. And a wax in an amount of from 1 to 15% by weight. 2. The developer according to claim 1, wherein the wax is a rice wax having a carbon number distribution peak of an acid component of a fatty acid having 24 carbon atoms. 3. The developer according to claim 1, wherein the wax is a synthetic ester wax of behenic acid and alcohol. 4. An image carrier, provided on the image carrier,
A binder resin, a colorant, and an ester component having a carbon number distribution peak at 40 to 100 carbon atoms as a main component, and the peak of the carbon number distribution of the acid component accounts for 60% or more of the entire acid component. The content is 0.1 to the total weight of the binder resin
A developing device for containing a developer containing 15% by weight of wax and for visualizing an electrostatic latent image formed on the surface of the image carrier with the developer to form a developer image;
An image forming apparatus comprising: a transfer device for transferring the developer image to a transfer material; and a fixing device for fixing the transferred developer image to the transfer material. 5. The image forming apparatus according to claim 6, wherein the wax is rice wax having a carbon number distribution peak of an acid component of a fatty acid having 24 carbon atoms. 6. The image forming apparatus according to claim 4, wherein the wax is a synthetic ester wax of behenic acid and an alcohol. 7. The image forming apparatus according to claim 1, wherein the fixing device is of a heat roller type, and at least a heat roller that comes into contact with an image is an elastic roller coated with a fluorine-containing resin. .