JP2002148931A - Toner supply roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner supply roller capable of obtaining an image without a failure such as uneven pitch and uneven density. SOLUTION: In the toner supply roller having a toner cartridge 4 in which toner being developer is stored, the toner supply roller 5 and a development roller 6, ad consisting of a foam elastic body to be mounted on a developing device to form the toner image by supplying the toner to a electrostatic latent image on the surface of a photoreptor, its compression spring constant is 0.25 to 5.0 N/mm and surface friction is 0.4 to 1.2 N.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner supply roller in a developing device of a printer for electrophotography, electrostatic recording, and the like, and more particularly, to a toner cartridge containing toner as a developer, a toner supply roller, and a development roller. And a toner supply roller mounted on a developing device that supplies toner to an electrostatic latent image on the surface of a photoreceptor to form a toner image.

[0002]

2. Description of the Related Art In recent years, a conductive roller system has been widely adopted as a developing roller and a toner supply roller used in a developing device arranged in a developing process in an electrophotographic apparatus such as an electrophotographic copying machine, a laser beam printer, and a facsimile. I have. In such a method, the toner is frictionally charged by rubbing the toner supply roller against the developing roller. Therefore, the toner supply roller has a stable friction property (pressing force) with the developing roller and a high toner supply to the frictional portion. Is required. Conventionally, a foamed elastic material obtained by foaming rubber, urethane, or the like is generally used for this type of toner supply roller.

[0003]

However, when the present inventors examined the performance of a conventional toner supply roller made of a foamed elastic body, the toner conveyed to the developing roller adhered to the toner regulating blade, Moreover, when this toner fixing layer gradually grows and eventually becomes a hindrance to the toner layer carried on the developing roller, a portion where the carried toner layer cannot pass occurs, and the toner is developed in a state where toner does not exist. As a result, it was found that a defect such as white spots due to non-supply of toner may occur in the developed image. The present invention has been made in view of such conventional circumstances, and provides a developing device equipped with a toner supply roller made of a foamed elastic material, which can obtain an image without a defect such as white spots due to non-supply of toner. The purpose is to do.

[0004]

The inventors of the present invention have studied the toner supply roller which has caused the above-described image defects, and have found the following. That is, the toner supply roller rubs the toner against the developing roller in order to charge the toner existing between the toner supply roller and the developing roller at the same time as the toner supply. To increase the damage of
It has been found that the toner is deteriorated and the deteriorated toner is easily fixed. As a result of further studies, it has been found that the rubbing force is greatly affected by the hardness and frictional resistance of the toner supply roller and the pressing force of the toner supply roller / developing roller. It has been found that when the hardness (compression spring constant) and the frictional resistance of the toner supply roller and the pressing force of the toner supply roller / developing roller are made suitable, an image without any trouble can be formed. The present invention has been made based on such findings.

That is, the present invention comprises a toner cartridge containing a toner as a developer, a toner supply roller and a development roller, and supplies toner to an electrostatic latent image on the surface of a photoreceptor to form a toner image. A toner supply roller made of a foamed elastic material mounted on an apparatus, wherein a compression spring constant is 0.25 to 5.0 N / mm and a surface friction resistance is 0.4 to 1.2 N. Is provided.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The toner supply roller of the present invention has a hardness (compression spring constant) of 0.25 to 5.0 N / mm, and the compression spring constant is 0.4 to 4.0 N / mm. mm, particularly preferably 0.7 to 3.0 N / mm. If the compression spring constant is less than 0.25 N / mm, there is a disadvantage that the toner is not sufficiently triboelectrically charged.
If it exceeds N / mm, there is an inconvenience that the toner is greatly damaged. The toner supply roller of the present invention includes:
The frictional resistance of the foamed elastic body forming the surface is 0.4 to 1.2N, preferably 0.4 to 0.8N. This frictional resistance is 0.4
If it is less than N, there is a disadvantage that the toner cannot be transported because the slip is too large, and if it exceeds 1.2 N, the damage to the toner becomes large, so that there is a disadvantage that the toner is easily deteriorated.

The average foam cell diameter of the foamed elastic body forming the toner supply roller is preferably 20 to 400 μm, more preferably 100 to 300 μm. If the average foam cell diameter is less than 20 μm, clogging with toner may occur, and the hardness near the surface of the roller may increase. If it exceeds 400 μm, the amount of toner entering the inside of the roller increases. Therefore, there is a possibility that a suitable toner supply cannot be performed. Further, the number of cells of the foamed elastic body is preferably 6 to 260 cells per 1 mm ² , and more preferably 10 to 100 cells. If the number of cells is less than 6, the toner supply to the developing roller may not be performed uniformly. If the number of cells exceeds 260, scraping of the toner remaining on the developing roller becomes insufficient. There is a risk. When the toner supply roller of the present invention is mounted on the developing device, the deformation of the roller when the toner supply roller comes into contact with the development roller is substantially due to the deformation of the toner supply roller. The amount of bite by the roller is 0.5 to 2 mm, preferably 0.5
It is preferable to dispose so that the distance is about 1.5 mm. If the amount of bite by the developing roller of the toner supply roller is less than 0.5 mm, there is a possibility that the toner remaining on the developing roller cannot be sufficiently scraped off. If the amount exceeds 2 mm, damage to the toner may increase. There is.

The foamed elastic body forming such a toner supply roller may be any foamed elastic body having the above characteristics, such as ester-based polyurethane foam, ether-based polyurethane foam, nitrile rubber, ethylene propylene rubber, and ethylene propylene diene. Examples include foams of rubber materials such as rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, acrylic rubber, chloroprene rubber, butyl rubber, and epichlorohydrin rubber. These may be used alone or in combination of two or more to form a foam. Of these, ester polyurethane foam, ether polyurethane foam, nitrile rubber foam, ethylene propylene rubber foam, ethylene propylene diene rubber foam, and silicone rubber foam are particularly preferred. For the purpose of controlling frictional resistance, the foam raw material can be mixed with silicone oil or the foam surface can be coated with silicone oil.

Further, the toner supply roller according to the present invention comprises:
It may be conductive, and can be produced by forming a conductive foamed elastic layer on the outside of a good conductive shaft in the same manner as conventionally used as a conductive toner supply roller. For metal shafts, steel materials such as sulfur free-cutting steel plated with zinc, aluminum,
Examples include stainless steel and phosphor bronze.
For the conductive foamed elastic layer, a foamed elastic material obtained by adding a conductive agent to an appropriate foamed elastic body and imparting conductivity is used. Also in the case of the conductive foamed elastic body, the number of cells is preferably 6 to 260 cells per 1 mm ² ,
Are more preferred.

As the conductive agent to be added when imparting conductivity to the foamed elastic body, an ionic conductive agent or an electronic conductive agent is used. Examples of the ionic conductive agent include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (eg, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (eg, stearyltrimethylammonium), benzyltrimethylammonium, and a modified fatty acid dimethylethylammonium. Ammonium salts such as perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, ethyl sulfate, carboxylate and sulfonate, lithium and sodium Perchlorates of alkali metals and alkaline earth metals such as, potassium, calcium, magnesium,
Chlorate, hydrochloride, bromate, iodate, borofluoride, trifluoromethyl sulfate, sulfonate and the like can be mentioned.

Examples of the electronic conductive agent include conductive carbon such as Ketjen black and acetylene black;
SAF, ISAF, HAF, FEF, GPF, SRF,
Rubber carbon such as FT and MT; carbon for oxidation-treated ink, pyrolytic carbon, natural graphite, artificial graphite; conductive metal oxides such as tin oxide, titanium oxide and zinc oxide; nickel, copper, silver, Examples thereof include metals such as germanium.

These conductive agents may be used alone or in combination of two or more. The amount of addition is not particularly limited, but in the case of the ionic conductive agent, usually 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the foamed elastic body. Selected by range. On the other hand, in the case of the electronic conductive agent, it is selected in the range of 1 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of the rubber-based elastic body. Note that, in addition to the conductive agent, other rubber additives such as a known filler and a crosslinking agent can be appropriately added to the conductive elastic layer as needed.

Further, in the present invention, when the conductive foamed elastic body of the toner supply roller is formed of polyurethane foam, the acetone foam of the polyurethane foam is used so that the deposit on the surface of the roller does not fuse the toner. Since the extraction rate is preferably 5% by weight or less, it is necessary to sufficiently examine the amount of the conductive agent to be added.
That is, if a large amount of carbon black (for example, channel black) having a large amount of volatilization is blended, the acetone extraction ratio is increased, and if a carbon black having a large oil absorption (for example, acetylene black or high-structure oil furnace black) is blended, the acetone extraction ratio is increased. Can be reduced.

The developing roller used in the developing device of the present invention is conductive, and a conductive elastic layer is formed on the outside of a good conductive shaft in the same manner as that conventionally used as a conventional conductive developing roller. Things. The conductive elastic layer is made of an elastic material obtained by adding a conductive agent as described above to an appropriate rubber-like elastic body to impart conductivity. here,
The rubber-like elastic body is not particularly limited, and can be arbitrarily selected from those conventionally used in conductive developing rollers. Examples of the rubbery elastic body include nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, urethane rubber, acrylic rubber, chloroprene rubber, butyl rubber, and epichlorohydrin rubber. And the like. These may be used alone or in combination of two or more. Among them, nitrile rubber, urethane rubber, epichlorohydrin rubber,
Ethylene propylene rubber, ethylene propylene diene rubber, and silicone rubber are preferred.

In the developing roller according to the present invention, in order to control frictional resistance and prevent contamination of the photosensitive member, etc.
For example, a thickness 1 made of a crosslinkable resin such as an alkyd resin, a phenol resin, a melamine resin and a mixture thereof.
It is preferable that a resin coating layer having a thickness of 100 μm is provided on the roller surface. These crosslinkable resins may contain various additives such as a charge control agent, a lubricant, a conductive agent, and other resins, if desired. The resin coating layer is usually
A dipping method, a roll coater method, a doctor blade method, using a coating liquid obtained by dissolving or dispersing a cross-linkable resin, a cross-linking agent, and various additives (using an alcohol-based solvent such as methanol or a ketone-based solvent such as methyl ethyl ketone as a solvent). After being applied on the elastic layer by a spray method or the like, it can be formed by drying at room temperature or at a temperature of about 50 to 170 ° C. and curing by crosslinking.

FIG. 1 is a schematic view of a developing section of a laser printer which is an example of a developing apparatus equipped with a toner supply roller of the present invention. Reference numeral 1 in the figure denotes a photoconductor, whose surface is uniformly charged by a primary charger 2, and then an image signal transmitted from a control unit (not shown) is converted into an optical signal using an LED array print head 3. After conversion, this is exposed on the surface of the photoreceptor 1 to form an electrostatic latent image. This electrostatic latent image is
The toner image is formed by being stored in the toner cartridge 4 and being developed by the toner supplied to the photoconductor 1 via the toner supply roller 5 and the developing roller 6. The toner image formed on the surface of the photoreceptor 1 is transferred to a paper surface supplied from a paper magazine 7 by a transfer charger 8 and fixed by a thermal fixing device 9, and the paper is transported and discharged in the direction of the arrow. The photoreceptor 1 after the transfer is returned to the initial state by the cleaning unit 10.

FIG. 2 is a schematic view showing a state of toner supply and frictional charging by the toner supply roller 5 and the developing roller 6, and FIG. 2B is an enlarged view of a portion indicated by a symbol A in FIG. It is. Since the contact portion 60 of the developing roller 6 with the toner supply roller 5 and the contact portion 50 of the toner supply roller 5 with the development roller 6 move in the directions of the arrows, the toner sandwiched between them is in contact. Due to the frictional force with the part 50, as shown in FIG. 2B, the toner is frictionally charged by sliding on the contact part 60 in the direction opposite to the traveling direction. Slip occurs between the toner and the contact portion 60 to charge the toner, and the charged toner is supplied onto the developing roller. Therefore, by using a toner supply roller having an appropriate frictional resistance with the toner, both the frictional force between the toner supply roller and the toner (toner holding property) and the frictional force between the developing roller and the toner (toner slipping property) are improved. To be
The toner can be supplied and the toner charged with little damage to the toner, and as a result, development without image defects can be performed.

[0018]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention. Examples 1 to 3 and Comparative Examples 1 to 4 The developing roller A and the toner supply rollers B, C, D, E, F, G or H are combined into the printer shown in FIG. An image was formed in an environment of (25 ° C., 50% RH), and the image quality of the image was evaluated.

The developing roller A used here was manufactured by the following method. Polyether polyol having a molecular weight of 5,000 by adding propylene oxide and ethylene oxide to glycerin (OH value: 33 mgKOH / g)
100 parts by weight, 1.0 part by weight of 1,4-butanediol,
0.5 parts by weight of nickel acetylacetonate, 0.01 parts by weight of dibutyltin dilaurate and 0.2 parts by weight of sodium perchlorate were added and mixed using a mixer to prepare a polyol composition. After stirring and defoaming the polyol composition under reduced pressure, 17.5 parts by weight of urethane-modified MDI (diphenylmethane diisocyanate) was added, and the mixture was stirred for 2 minutes.
Next, this was cast into a mold in which the metal shaft was heated to 110 ° C. in advance, and cured at 110 ° C. for 2 hours to form a conductive elastic layer on the outer periphery of the metal shaft to obtain a roller. The surface of the obtained roller was polished, and the surface was adjusted to a JIS 10-point average roughness of 4.0 μmRz.

Next, as a resin for forming the resin coating layer,
Oil-free alkyd resin (manufactured by Dainippon Ink, M6
402) and a melamine resin (manufactured by Dai Nippon Ink Co., Ltd., Super Beckamine L-145-60, solid content ratio 60% by weight) so that the oil-free alkyd resin and the melamine resin have a solid content weight ratio of 80/20. Mixed with methyl ethyl ketone as a solvent, and the solid concentration is 20% by weight.
It was adjusted to be. 20 parts by weight (20 phr) of carbon (De) per 100 parts by weight of the solid content of this mixture
Gussa, Printex L6: average particle size 18
nm) and dispersed using a paint shaker to prepare a coating solution. The roller was immersed in the coating solution, pulled up, and heated at 130 ° C. for 3 hours to produce a developing roller A having a cured resin coating layer. The outer diameter of the obtained developing roller A was 16.0 mm.

Further, the toner supply rollers B,
C, D, E, F, G and H were prepared by the following method. 20 wt. Parts of a polymer polyol having a solid content of about 28% using a polyether polyol having a molecular weight of 5,000, which is obtained by adding 15 wt.% Of ethylene oxide and 85 wt.% Of propylene oxide to glycerin, and 75 wt. 40% by weight of a hydrophilic polyether polyol having a molecular weight of 3400 to which 25% by weight of an oxide is added, and 15% by weight of ethylene oxide and 85% of propylene oxide in glycerin.
After sufficiently stirring 40 parts by weight of a polyether polyol having a molecular weight of 4800 and 21 parts by weight of tolylene diisocyanate (TDI-80),
C., and the stirring was repeated every 12 hours to obtain a polyether polyol prepolymer after 48 hours. Next, based on 100 parts by weight of this prepolymer, 27 parts by weight of water-dispersed carbon (carbon content: 8% by weight) containing conductive carbon, and 70% di- (dimetalaminoethyl) ether as a catalyst Polyether-modified silicone foam stabilizer comprising 0.1 part by weight of a propylene glycol solution and 70% by weight of ether chains of polyoxyethylene
A mixture in which 2.5 parts by weight was dissolved (29.6 parts by weight in total) was mixed. This mixture is filled into a cylindrical mold, the inner surface of which is coated with Teflon and the end is sealed by a removable cap, the cap is closed and the cap is closed and adjusted to 70 ° C. It was left in a hot-air oven for 8 to 10 hours to obtain polyurethane foams of various hardnesses (compression spring constants) which were foam-cured.

The cured polyurethane foam was removed from the mold by removing the cap at the end of the mold, and passed through a roll to be subjected to a glassing treatment. Next, a hole having an inner diameter of 5 mm was formed at the center of the circle at the end face of the cylinder, and a zinc-coated shaft coated with an adhesive and having an outer diameter of 6.0 mm and a length of 240 mm was press-fitted. After heating and bonding for 15 minutes in an open at 60 ° C., the outer diameter of the cylinder is 13.0 mm
After grinding with a grindstone so that the frictional resistance is adjusted by changing the amount of application to each roller surface and applying silicone oil, toner supply rollers B, C, and C, each having a different hardness (compression spring constant) and frictional resistance. D, E, F, G and H were prepared. The number of cells and the cell diameter of the foamed elastic body can be determined by taking a photograph at a magnification of 40 to 60 times using a CCD video camera manufactured by Hilox Corporation and measuring the cell diameter and the cell number of the image. I asked. The number of cells was measured according to JIS K6402.

As shown in FIG. 3, each of the toner supply rollers B to H is a foamed elastic roller in which a foamed elastic roller 12 is disposed around a metal rotating shaft 11. This toner supply roller was arranged as the toner supply roller 5 of the printer shown in FIG. 1, and an image forming test was performed. In this printer, the center distance between the developing roller 6 and the toner supply roller 5 is fixed at 13.5 mm, and since the outer diameter of the developing roller A is 16.0 mm, a toner supply roller having an outer diameter of 13.0 mm is provided. In this case, the amount of biting of the developing roller A into the toner supply roller is 1.0 mm. In the present embodiment, the compression spring constant of the toner supply roller was measured in the circumferential direction of the roller and in the longitudinal direction of the roller by the measuring method shown in FIG. As shown in FIG. 4, the rotation shaft 11 of the toner supply roller 5 is
The force gauge 14 placed above the roller 12 is moved downward at a constant speed (0.1 mm / sec), and a disk-shaped compression plate having a diameter of 13 mm provided at the tip of the force gauge 14 is identified. About jig (disk indenter) 15
The compression was performed to a depth of 1.0 mm, and the spring constant was calculated from the measured stress-strain curve. This measurement was performed at intervals of 30 mm in the longitudinal direction of the roller and at 30 degrees in the circumferential direction of the roller, and was calculated as an average value.

In this embodiment, a friction tester “HEIDON Tribogear” manufactured by Shinto Kagaku Co., Ltd. is used, and FIG.
The surface frictional resistance of the roller was measured according to the method described in (1). As shown in FIG. 5, the toner supply roller 5 was fixed to the movable stage 16 and moved in the direction of the arrow at a friction speed of 100 mm / min. The mating member of the friction was an acrylic round bar 17 having a diameter of 12 mm, which was arranged in a direction perpendicular to the toner supply roller 5 and was rubbed by a load 19 with a load of 1N. The friction resistance at this time was measured by the load cell 18. The reason why the acrylic material was selected as the friction partner material is that the main component of the toner is similar to the acrylic material, and the friction by this combination simulates the friction between the toner supply roller and the toner. The toner supply roller used in this embodiment is formed by the method shown in FIG.
After measuring the compression spring constant and measuring the frictional resistance by the method shown in FIG. 5, the image forming test was performed by arranging it as the toner supply roller 5 of the printer shown in FIG. The developing roller A was disposed as the developing roller 6. The image evaluation and the image formation test were performed using A4
Paper of size is fed vertically and kept at a constant temperature and humidity (25 ° C / 5
(0% RH) environment. The image evaluation was performed after printing 10 dark gray solid images and then 7% as a continuous image formation test.
The printing was performed by continuously printing 1,000 solid gray images. Table 1 shows the results. In the table below, the image quality evaluation is performed by forming a solid dark gray image, and when the image quality is uniform and good (○), and when the image is uneven due to uneven shading (x).
And In addition, the occurrence of a defect of a blank image in continuous image formation is “none” when no image is generated up to 1000 sheets,
In the case of occurrence, the number of images formed so far is shown.

[0025]

[Table 1]

The following can be seen from the results shown in Table 1. Hardness (compression spring constant) of toner supply roller is 0.25 ~
Even at 5.0 N / mm, if the frictional resistance of the toner supply roller exceeds 1.2 N, image defects such as blank image defects due to toner deterioration and uneven density in image quality occur. I have. Hardness (compression spring constant) of toner supply roller is 0.25 ~
Even at 5.0 N / mm, if the frictional resistance of the toner supply roller is less than 0.4 N, there is no white spot image defect due to toner deterioration, but image defect such as uneven density in image quality. It has occurred. Even when the frictional resistance of the toner supply roller is 0.4 to 1.2 N, the hardness (compression spring constant) of the toner supply roller is 0.25.
If it is less than N / mm, no white spot image defect due to toner deterioration occurs, but image defects such as uneven density in image quality have occurred. Even if the frictional resistance of the toner supply roller is 0.4 to 1.2 N, the hardness (compression spring constant) of the toner supply roller is 5.0 N
/ Mm, image defects such as white spot image defects due to toner deterioration and density unevenness in image quality have occurred.

[0027]

When the toner supply roller of the present invention is mounted on a developing device, the toner supply roller presses the toner against the development roller, supplies the toner to the development roller, and frictionally charges the supplied toner. Therefore, it is possible to perform development without causing image deterioration such as white spots without causing toner deterioration, and it is also possible to suitably scrape off the toner remaining on the developing roller. Good images without defects can be formed over a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a developing unit of a laser printer which is an example of a developing device according to the present invention.

FIG. 2 is a schematic diagram illustrating a state of toner triboelectric charging by a toner supply roller and a developing roller of the present invention.

FIG. 3 is a schematic perspective view of a toner supply roller of the present invention.

FIG. 4 is a schematic view showing a method of measuring a compression spring constant of the toner supply roller shown in the embodiment.

FIG. 5 is a schematic diagram showing a method for measuring the surface frictional resistance of the toner supply roller shown in the example.

[Explanation of symbols]

 1: Photoreceptor 2: Primary charger 3: LED array print head 4: Toner cartridge 5: Toner supply roller 6: Developing roller 7: Paper magazine 8: Transfer charger 9: Thermal fixing device 10: Cleaning unit 11: Rotation Shaft 12: Foam elastic roller 13: V block 14: Force gauge 15: Compression jig (disc indenter) 16: Movable stage 17: Acrylic round bar 19: Load load

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 2H077 AC04 AD06 AE02 AE04 FA13 FA14 FA22 FA27 3J103 AA02 AA13 AA32 BA31 BA41 FA02 FA05 FA18 GA02 GA52 HA03 HA05 HA11 HA12 HA15 HA18 HA20 HA32 HA33 HA36 HA37 HA48 HA52 HA53

Claims (5)

[Claims] An image forming apparatus includes a toner cartridge containing toner as a developer, a toner supply roller, and a developing roller, and is mounted on a developing device that supplies toner to an electrostatic latent image on a photoreceptor surface to form a toner image. And a compression spring constant of 0.25 to 5.0.
N / mm and a surface frictional resistance of 0.4 to 1.2N. 2. The foamed elastic body has an average foamed cell diameter of 2
0 to 400 μm, 6 to 260 cells per 1 mm ²
The toner supply roller according to claim 1, wherein the toner supply roller is a unit. 3. The foamed elastic body has an average foamed cell diameter of 1
The number of cells per 100 to 300 μm / mm ² is 10 to 1
3. The toner supply roller according to claim 1, wherein the number of the toner supply rollers is 100 and the compression spring constant is 0.4 to 4.0 N / mm. 4. 4. The toner supply roller according to claim 1, wherein the toner supply roller is formed by forming a conductive foamed elastic layer outside a good conductive shaft. 5. The toner supply roller according to claim 4, wherein the good conductive shaft is a metal shaft, and the conductive foamed elastic layer is provided with conductivity by conductive carbon.