JP2001042630A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a good image, even under serve environmental conditions and to maintain satisfactory image formation over a long time period, even if image formation is carried out repeatedly by using polyurethane as the principal constituent of each of a developer supporting roller, a developer supplying roller and a developer layer forming blade. SOLUTION: In this developing device, polyurethane is used as the principal constituent for each of a developer support roller, a developer supplying roller and a developer layer forming blade. The polyurethane of the developer carrier roller is a polyurethane elastic body, having 40-80 deg., Asker C hardness, the polyurethane of the developer supplying roller is polyurethane foam having 30-90 deg. Asker F hardness and the polyurethane of the developer layer forming blade is a polyurethane having 30-90 deg. JIS A hardness. The developer supporting roller is obtained, by forming an electrically conductive elastic layer 12 on the periphery of a shaft 11, having satisfactory electrical conductivity and further forming a coating layer 13 on the surface of the electrically conductive elastic layer 12. The electrically conductive elastic layer 12 comprises a polyurethane material provided with electrical conductivity by adding an electrically conductive agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an electrophotographic apparatus such as a copying machine, a facsimile, a printer, or the like, or an electrostatic recording apparatus, and an image forming apparatus having the same.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, a one-component developer is supplied to an image forming body such as an electrostatic latent image holder holding an electrostatic latent image. As an image forming method for visualizing the developer by attaching the developer to a latent image, a pressure developing method is known (US Pat.
No. 52012, No. 3731146, etc.). In this pressure development method, a developer carrying member carrying a developer is brought into contact with an electrostatic latent image holding member holding an electrostatic latent image, and the developer is formed on the latent image of the electrostatic latent image holding member. An image is formed by attaching the developer, and therefore, it is necessary to form the developer carrier from a conductive elastic material having conductivity and elasticity. In other words, in this pressure development method, as shown in FIG. 1, for example, a developer is supplied between a developer supply roller 3 for supplying a developer 10 and an electrostatic latent image holder 5 holding a latent image. A developer carrying roller 4 is provided, and the developer supply roller 3, the developer carrying roller 4, and the electrostatic latent image holder 5 are rotated in the direction of the arrow, so that the developer 10 is The developer is supplied to the surface of the carrying roller 4, and the developer is formed into a uniform thin layer by the developer layer forming blade 2. In this state, the developer carrying roller 4 rotates while being in contact with the electrostatic latent image holder 5. As a result, the charged developer formed in a thin layer shape adheres to the latent image on the electrostatic latent image holding member 5 from the developer carrying roller 4, and the latent image is visualized. Then, the transfer roller 6 causes the electrostatic latent image holding member 5 to move.
The upper developer image is transferred to the recording medium 9. Reference numeral 7 denotes a cleaning device, and a developer remaining on the surface of the electrostatic latent image holding member 5 after transfer is removed by a cleaning blade 8 provided in the cleaning device 10.

The developing process will be described in more detail. The developer 10 is supplied to the nip between the developer supply roller 3 and the developer carrying roller 4 and between the developer carrying roller 4 and the developer layer forming blade 2. In the nip portion, the toner is triboelectrically charged so as to have a predetermined positive or negative charge, and is electrostatically attracted and carried on the surface of the developer carrying roller 4 whose surface is charged in the opposite polarity to the developer. The developer carried on the surface of the developer carrying roller 4 is transferred to the surface of the developer carrying roller 4 and the electrostatic latent image carrier 5 at a nip portion between the electrostatic latent image carrier 5 and the developer carrying roller 4. Move to the latent image portion on the electrostatic latent image holding member 5 and adhere to it to form a visible image. The developer carrying roller 4 is required to have a function of charging the developer and a function of transmitting a developing bias to the surface of the developer to maintain the surface of the developer at an appropriate potential. Is formed of a conductive elastic body having As the conductive elastic body, an elastic body such as polyurethane, silicone, nitrile rubber, ethylene-propylene rubber, epichlorohydrin rubber, or the like, which is blended with a conductive agent to provide conductivity is used. Since the developer supply roller 3 is required to have a function of replenishing the developer and a function of frictionally charging the developer, the developer supply roller 3 is formed of a conductive foam in which a conductive agent is blended to impart conductivity. Have been. As the foam, a foam such as polyurethane, silicone, and ethylene-propylene rubber is used. Since the developer layer forming blade 2 is required to have a function of frictionally charging the developer and a function of regulating the layer thickness of the developer layer, a leaf spring-like metal plate having elasticity, resin or rubber is used. And the like, or a composite of a metal plate and an elastic body. As the resin or rubber, silicone, polyurethane, nitrile rubber, ethylene-propylene rubber, polyester, fluororesin, polyamide and the like are used.

[0004]

However, the above-mentioned conventional developing device has the following disadvantages, and therefore a solution has been demanded. That is, under environmental conditions of normal temperature / normal humidity (usually, 20 to 25 ° C./45 to 60%), the hardness and resistance of the material forming the developer carrying roller, the developer supply roller, and the developer layer forming blade ,
Even if a developing device is designed with an optimal combination of frictional force, etc., the environmental dependence of the viscoelastic behavior of those materials differs, so under severe environmental conditions such as high temperature / high humidity and low temperature / low humidity, Image fog, insufficient image density, and image unevenness tend to occur. In the early stage of printing,
Even in a developing device that can form a good image even under severe environmental conditions such as high temperature / high humidity or low temperature / low humidity, if image formation is repeated, image fogging and image There is a problem that insufficient density and image unevenness occur. The present invention has been made in view of the above circumstances, and forms a good image even under severe environmental conditions such as high temperature / high humidity and low temperature / low humidity. It is an object of the present invention to provide a developing device capable of maintaining good image formation by using the developing device and an image forming apparatus including the same.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventors have in mind a constituent material having various functions required in a developer carrying roller, a developer supply roller and a developer layer forming blade. As a result of intensive studies and investigations, when the main components constituting the developer carrying roller, the developer supply roller and the developer layer forming blade are made of polyurethane, the problem caused by the difference in viscoelasticity is solved, and the image It has been found that good image formation can be maintained for a long time even if the formation is repeated.
The present invention has been completed based on such findings.
That is, the present invention includes a developer supply roller that supplies a developer to an outer peripheral surface of a developer carrying roller, and a developer layer forming blade that forms a developer layer on the outer peripheral surface of the developer carrying roller, In a developing apparatus for developing a visible image by attaching a developer carried on an outer peripheral surface of the developer carrying roller to the electrostatic latent image held on the latent image holding body, the developer carrying roller and the developer It is an object of the present invention to provide a developing device characterized in that the main components constituting the supply roller and the developer layer forming blade are made of polyurethane, and an image forming device equipped with the developing device.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The main structure and main function of a developing device according to the present invention are shown in FIG. 1. Details have been described in the above-mentioned prior art and will not be described. In the developing device of the present invention, the main components constituting the developer carrying roller, the developer supply roller and the developer layer forming blade are polyurethane, and the problem caused by the difference in viscoelastic behavior as described above is solved. Since the polyurethane has good wear characteristics and a long life, the developing device also has a long life. The developer carrying roller used in the developing device of the present invention has a conductive elastic layer 12 formed on the outer periphery of a good conductive shaft 11 as shown in FIG. As exemplified in (1), there is a material in which a coating layer 13 is further formed on the surface of the conductive elastic layer 12. As the shaft 11, any material having good conductivity can be used.
A metal shaft such as a metal core made of a solid metal body or a metal cylindrical body having a hollow inside is used. Examples of the metal forming the shaft include iron, copper, nickel silver, stainless steel, and phosphor bronze. As the conductive elastic layer 12, an elastic body obtained by adding a conductive agent to a polyurethane material to impart conductivity is used. A polyurethane material is produced from a polyol component and a polyisocyanate component as main raw materials. Examples of the polyol component include polyether polyol, polyester polyol, and polyolefin polyol. Examples of the polyether polyol include polyols obtained by addition polymerization of glycerin and the like with an alkylene oxide such as ethylene oxide and propylene oxide, and polyols such as polytetramethylene ether glycol, ethylene glycol, propanediol, and butanediol. Examples of the polyester polyol include condensed polyester polyols obtained by condensation of a dicarboxylic acid and a diol or a triol, etc., and lactone polester polyols based on lactone ring-opening polymerization and polyether polyols obtained by ring-opening polymerization of a lactone. And an ester-modified polyol obtained by ester-modifying the compound with a lactone. Examples of the polyolefin polyol include polyisoprene polyol, polybutadiene polyol, and hydrogenated products thereof. Among these polyols, a polyolefin polyol is preferable from the viewpoint of obtaining a polyurethane material having low environmental condition dependency.

The polyisocyanate component includes aromatic polyisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude diphenylmethane diisocyanate (crude MDI), isophorone diisocyanate, hydrogenated genenyl methane diisocyanate, and hydrogenated tolylene diisocyanate. Polyisocyanates having no unsaturated bond, such as isocyanate and hexamethylene diisocyanate, and derivatives thereof, such as carbodiimide-modified and glycol-modified products;
Modified isocyanurate and the like can be mentioned. Among these polyisocyanate compounds, aromatic polyisocyanates are preferred from the viewpoint of obtaining a polyurethane material having good abrasion resistance. MDI, Crude MDI
(A so-called MDI-based polyisocyanate) is preferable because the reaction completion with the polyol is good. When a polyurethane is produced from a polyol component and a polyisocyanate component, an excess polyisocyanate and a polyol are preliminarily reacted to form a prepolymer, and the resulting prepolymer is further reacted with a polyol to cure the polyurethane. Manufacturing is preferable because a roller having excellent mechanical properties and good wear resistance can be obtained.

On the other hand, the conductive agent added to the conductive elastic layer includes an ionic conductive agent and an electronic conductive agent. Examples of the ionic conductive agent include dodecyl such as tetraethylammonium, tetrabutylammonium and lauryltrimethylammonium. Perchlorates, chlorates, hydrochlorides, bromine such as octadecyltrimethylammonium, benzyltrimethylammonium, modified aliphatic dimethylethylammonium, lauroylaminopropyldimethylethylammonium such as trimethylammonium, hexadecyltrimethylammonium and stearyltrimethylammonium Salts such as acid salts, iodate salts, borohydrofluoric acid salts, sulfate salts, alkyl sulfate salts, carboxylate salts, and sulfonate salts; alkali salts such as lithium, sodium, calcium, and magnesium Metal or alkaline earth perchlorates of metals, chlorates, hydrochlorides, bromates, iodates, fluoroboric acid salts, trifluoromethyl sulfate, and sulfonic acid salts. Examples of the electronic conductive agent include conductive carbon black such as Ketjen black and acetylene black; SAF, ISAF, HAF, and FE.
Carbon black for rubber such as F, GPF, SRF, FT, MT; carbon black for ink which has been subjected to oxidation treatment;
Pyrolytic carbon black, graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; nickel,
Powders such as metals such as copper can be used.

These conductive agents may be used alone,
You may use it combining the above. The amount of addition
In the case of an ion conductive agent, 100% by weight of the above polyurethane component
Parts by weight, preferably 0.01 to 5 parts by weight, more preferably 0.05 to 2 parts by weight.
Parts by weight; for electronic conductive agents, 1
To 50 parts by weight, preferably 5 to 40 parts by weight
be able to. By adjusting the amount of conductive agent added, the conductivity
The specific resistance of the elastic layer is 10^Three-10 ^TenΩ · cm, especially
10^Four-10⁸It is preferable to adjust to the range of Ωcm
No. The conductive elastic layer must have a material other than the conductive agent.
Additives, such as conventionally known fillers, stabilizers, and lubricants, if necessary
Can be appropriately added. Hardness of this conductive elastic layer
Is preferably 40-80 ° in Asker C hardness.
And particularly preferably 50 to 70 °. Asker C hardness 8
If the angle exceeds 0 °, the developer carrying roller becomes hard and an electrostatic latent image is formed.
Good image formation due to small contact area with holder
May not be possible, and may damage the developer
Developer for electrostatic latent image carrier and developer layer forming blade. Fixation
And the like, which causes image defects. Conversely, low
If the hardness is too high, the electrostatic latent image holding member and the developer layer
The friction with the blade increases, resulting in image defects such as jitter.
May occur.

The conductive elastic layer of the developer carrying roller preferably has a small compression set since the developer carrying roller is used in contact with the electrostatic latent image holding member or the developer layer forming blade. , Specifically, 20% or less, particularly 10%
The following is preferred. In particular, polyurethane rubber is particularly preferable because the compression set can be designed to be small. In addition,
The compression set is a value measured according to JIS K6301. The surface roughness of the conductive elastic layer is determined according to JIS.
10-point average roughness of 15 μm Rz or less, especially 3 to 10 μm
It is preferably Rz. This average roughness is 15 μmR
When z exceeds z, it is necessary to form a thick coating layer on the surface of the developer carrying member, and as a result, the surface of the developer carrying member becomes hard, and the developer is damaged, and the electrostatic latent image carrier and the developer layer are damaged. It is not preferable because the developer adheres to the forming blade and the image is defective. On the other hand, if the Rz is too small, when the coating layer is formed, the Rz on the surface of the developer carrying member becomes too small, and the amount of the developer carried becomes small, so that the image density may be reduced. The surface roughness was measured using a surface roughness meter “Surfcom 590A” (manufactured by Tokyo Seimitsu Co., Ltd.).
Measurement length 2.4mm in circumferential direction, measurement speed 0.3mm / sec,
It is a value obtained by measuring at 300 or more locations so that there is no deviation in the shaft direction and circumferential direction of the roller at a cutoff wavelength of 0.8 mm (the same applies to the following).

In the developer carrying roller used in the present invention, in order to control the chargeability and adhesion of the developer, the frictional force with the electrostatic latent image holding member and the developer layer forming blade is reduced. Alternatively, a coating layer made of a resin or the like can be provided on the surface of the conductive elastic layer in order to prevent contamination of the electrostatic latent image holding member by the elastic body. This coating layer is formed of a material containing a resin. Resin materials include silicone resin, urethane resin, polyamide resin,
Polyester resin, polycarbonate resin, acrylic urethane resin, epoxy resin, alkyd resin, melamine resin, urea resin, phenol resin, polyurea resin, silicone-modified acrylic resin, epoxy-modified silicone resin, silicone-modified alkyd resin, and the like. They may be used, or two or more kinds may be used in combination. Among these resins, a resin obtained by curing a resin having active hydrogen with a melamine resin is preferable in terms of high charging performance and good durability. Examples of the resin having active hydrogen include urethane resin, polyamide resin, polyester resin, acrylic urethane resin, epoxy resin, alkyd resin, silicone-modified acrylic resin, silicone-modified alkyd resin, and the like.

It is preferable that the coating layer of the developer carrying roller is adjusted so that the insolubility in a solvent is 70% by weight or more. Pressure contact marks may be formed on members that are in contact with the developer carrying roller, such as an image carrier and a developer layer forming blade, and as a result, a problem such as a horizontal black line may occur in an image. Particularly, those having a solvent insolubility of 80% by weight or more are preferable. The coating layer on the developer carrying roller is
Although the above-mentioned cured resin is the main component, in addition,
Including various additives such as charge control agents, lubricants, conductive agents, and other resins for the purpose of further improving the chargeability of the developer, reducing the frictional force with other members, and imparting conductivity. Can be. In the developer carrying roller used in the present invention,
The resistance of the coating layer is preferably higher than the resistance of the conductive elastic layer in adjusting the resistance of the developer carrying roller,
A preferable specific resistance value of this coating layer is 10 ⁹ to 10 ¹⁶ Ω ·
cm, particularly preferably 10 ¹⁰ to 10 ¹⁵ Ω · cm. The resistance of the developer carrying roller is 1
0 ⁶ ~10 ¹² Ω, and particularly preferably ^{10 7} ~10 10 Ω. Further, the surface roughness of the developer carrying roller on which the coating layer is formed is preferably 10 μmRz or less, particularly preferably 1 to 8 μmRz in terms of JIS 10 point average roughness. If the average roughness exceeds 10 μmRz, the amount of charge of the developer becomes small or a reversely charged developer is generated, which is not preferable because image fogging occurs. On the other hand, if Rz is too small, the amount of developer carried is reduced, and the image density may be reduced.
As a method of forming the coating layer on the developer carrying roller,
The elastic material layer 1 is formed by dipping, a roll coater method, a doctor blade method, a spray method, or the like on a coating liquid obtained by dissolving or dispersing a resin material and various additives as necessary.
There is a method in which after coating on 7c, it is dried at room temperature or at a temperature of about 50 to 170 ° C., and cross-linked and cured to form.

The thickness of the coating layer can be about 3 to 50 μm, but is particularly preferably in the range of 5 to 30 μm. If the thickness of the coating layer is too small, local discharge occurs, and horizontal white lines are likely to occur in the image. On the other hand, if the thickness is too large, the developer carrying member becomes hard and damages the developer, causing the developer to adhere to the electrostatic latent image holding member and the developer layer forming blade, etc., causing image defects. Examples of the solvent used for preparing the coating liquid include alcohol solvents such as methanol, ethanol, isopropanol and butanol; ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone; aromatic hydrocarbon solvents such as toluene and xylene; Aliphatic hydrocarbon solvents such as hexane; alicyclic hydrocarbon solvents such as cyclohexane; ester solvents such as ethyl acetate; ether solvents such as isopropyl ether and tetrahydrofuran; amide solvents such as dimethylformamide; Examples thereof include halogenated hydrocarbon solvents such as chloroethane and the like, and mixed solvents thereof. In the present invention, ketone solvents and mixed solvents of ketone solvents and aromatic hydrocarbons are particularly preferably used.

The developer supply roller used in the present invention comprises:
An elastic foam layer 15 is formed on the shaft 14 and its outer periphery as exemplified in FIG. The elastic foam layer 15 is made of a polyurethane foam. As the polyurethane material forming the foam, the polyols and polyisocyanates described for the developer carrying roller can be used. As the polyol, a polyether polyol is preferable because it can easily produce a polyurethane foam and has resistance to hydrolysis by a developer. As the polyisocyanate, an aromatic polyisocyanate is preferred from the viewpoint of obtaining a polyurethane material having good abrasion resistance. Further, M
DI and crude MDI (so-called MDI-based polyisocyanate) are preferred because they have good reaction completion with the polyol. When a polyurethane is produced from a polyol component and a polyisocyanate component, an excess polyisocyanate and a polyol are preliminarily reacted to form a prepolymer, and the resulting prepolymer is further reacted with a polyol to cure the polyurethane. Manufacturing is preferable because a roller having excellent mechanical properties and good wear resistance can be obtained. As a method for producing a polyurethane foam, a method using a foaming agent such as water or a low-boiling compound (for example, isopentane) or a method involving mixing air bubbles by mechanical stirring is used. At this time, it is preferable to use a silicone foam stabilizer and various surfactants in combination for stabilizing the bubbles. The hardness of the polyurethane foam is preferably 30 to 90 ° in Asker F hardness, and particularly preferably 4 to 90 °.
0-70 ° is preferred. If the hardness is too high, the developer may be damaged or the developer carrying roller may be damaged. On the other hand, if the hardness is too low, it becomes difficult to triboelectrically charge the developer, so that the charge amount becomes insufficient, and the developer remaining on the developer carrying roller may not be sufficiently scraped off.

The density of the polyurethane foam is from 0.03 to 0.3.
It is preferably 5 g / cm ³ , particularly 0.05 to 0.4.
g / cm ³ is preferred. As a polyurethane foam,
Either open cells or closed cells can be used, but open cells are preferred from the viewpoint of reducing the permanent compression set of the polyurethane foam. The average cell diameter of the foam is important in the supply of the developer, and is 20 to 800 μm.
m is preferable, and 50 to 300 μm is particularly preferable. If the average cell diameter exceeds 800 μm, the developer supplied to the developer carrying roller may be non-uniform. If the average cell diameter is less than 20 μm, the supply of the developer may be insufficient. The average number of cells of the foam is also important in the supply of the developer, and from the viewpoint of optimizing the supply amount of the developer, 2
0 to 300 pieces / 25 mm is preferable, and especially 30 to 200 pieces.
Pcs / 25 mm is preferred. The developer supply roller includes a roller that makes the roller conductive and applies a bias voltage, and a roller that makes the roller non-conductive and does not apply a bias voltage. When imparting conductivity to the developer supply roller, the same conductive agent as that exemplified in the developer carrying roller is added to the polyurethane material. At this time, the specific resistance value of the polyurethane foam (elastic layer) is 10 ² to 10 ⁸ Ω ·
cm, preferably 10 ³ to 10 ⁶
The range of Ω · cm is preferable. The resistance of the developer supply roller is preferably 10 ³ to 10 ⁹ Ω, and 10 ⁴ to 1
0 ⁷ Ω is particularly preferred. Since the developer supply roller is used in contact with the developer carrying roller, the compression set is preferably small, specifically, 20% or less, particularly 1%.
0% or less is preferable. Particularly, a polyurethane foam is particularly preferable because the compression set can be designed to be small.
The compression set of the foam is a value measured according to JIS K 6382.

The developer layer forming blade used in the present invention has a support member 16a or 1 made of metal or resin as shown in FIG. 4 (a) and FIG. 4 (b).
6b in which a polyurethane elastic layer 17a or 17b is formed on at least the surface that comes into contact with the developer carrying roller;
As illustrated in FIG. 4C, a polyurethane elastic layer 17c is formed on at least a surface of the support member 16c which is in contact with the developer carrying roller, and the charge adjusting layer 1 is formed on the elastic layer 17c.
8 are laminated. As means for forming the elastic layer 17a or 17c on the surface of the support member 16a or 16c, generally, an elastic body formed by coating, integrally forming, or previously formed into a sheet shape and cut into an appropriate shape is used as the support member 16a or 16c. For example, a method such as bonding to the surface is adopted. As a means for forming the elastic layer 17b on the surface of the support member 16b, a method such as integral molding is generally employed. An adhesive layer may be provided between the support member 16a and the elastic layer 17a, between the support member 16b and the elastic layer 17b, and between the support member 16c and the elastic layer 17c as necessary. .

The metal forming the support member may be iron,
Copper, nickel silver, stainless steel, phosphor bronze, and the like. Examples of resins include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyurethane, polyamide, polyacetal, polycarbonate, and the like.
Examples include synthetic resins such as polyethylene terephthalate, polyimide, polyamide imide, polyester, phenol resin, melamine resin, silicone resin, epoxy resin, acrylic resin, methacryl resin, and urea resin. As the material for forming the support member, metal is preferable because it has elasticity, easily contacts the developer layer forming blade with the developer carrying roller, and has conductivity, so that a voltage can be applied. As the polyurethane material for forming the elastic layer, the polyols and polyisocyanates described for the developer carrying roller can be used. As the polyol, polyether polyol and polytetramethylene ether glycol are preferable from the viewpoint of obtaining a polyurethane material having good abrasion resistance. As the polyisocyanate, an aromatic polyisocyanate is preferred from the viewpoint of obtaining a polyurethane material having good abrasion resistance. Further, MDI and crude MDI (so-called MDI-based polyisocyanate) are preferable in that the reaction completeness with the polyol is good. When a polyurethane is produced from a polyol component and a polyisocyanate component, an excess polyisocyanate and a polyol are preliminarily reacted to form a prepolymer, and the resulting prepolymer is further reacted with a polyol to cure the polyurethane. Manufacturing is preferable because a roller having excellent mechanical properties and good wear resistance can be obtained.

The polyurethane elastic body forming the elastic layer preferably has a JISA hardness of 30 to 90 °, particularly preferably 40 to 70 °. If the hardness of the polyurethane elastic body is too high, the developer may be damaged or the developer may be fused. If the hardness is too low, the developer may be insufficiently charged, or the thickness of the developer layer may be insufficiently regulated. In the developer layer forming blade,
Some blades are conductive and apply a bias voltage, while others are nonconductive and do not apply a bias voltage. When imparting conductivity to the developer layer forming blade, the same conductive agent as that exemplified in the developer carrying roller is added to the polyurethane material. At this time, the specific resistance value of the polyurethane elastic body (elastic body layer) developer layer forming blade is preferably in the range of 10 ² to 10 ⁸ Ω · cm, and particularly preferably in the range of 10 ³ to 10 ⁶ Ω · cm. . Since the developer layer forming blade is used in contact with the developer carrying roller, the compression set is preferably small, specifically, 20% or less, particularly preferably 10% or less. Particularly, a polyurethane material is particularly preferable because the compression set can be designed to be small. The compression set is a value measured according to JIS K6301.

The charge adjusting layer 18 shown in FIG. 4C is provided for controlling the chargeability and adhesion of the developer or reducing the frictional force with the developer carrying roller. The charge adjusting layer is formed of a material containing a resin. Resin materials include silicone resin, urethane resin, polyamide resin, polyester resin, polycarbonate resin, acrylic urethane resin, epoxy resin, alkyd resin, melamine resin, urea resin, phenol resin, polyurea resin, silicone-modified acrylic resin, epoxy-modified silicone And alkyd resins modified with silicone. These may be used alone or in combination of two or more. Among these resins,
A resin obtained by curing a resin having active hydrogen with a melamine resin is preferable in terms of high charging performance and good durability. Examples of the resin having active hydrogen include urethane resin, polyamide resin, polyester resin, acrylic urethane resin, epoxy resin, alkyd resin, silicone-modified acrylic resin, silicone-modified alkyd resin, and the like.

The charge adjusting layer 18 is preferably adjusted so that the insolubility in a solvent is 70% by weight or more. If the insolubility is less than 70% by weight, the charge adjusting layer may be easily worn. . Particularly, those having a solvent insolubility of 80% by weight or more are preferable. The charge adjusting layer 18 is mainly composed of the above-mentioned cured resin. In addition, the charge adjusting layer 18 is charged for the purpose of further improving the chargeability to the developer, reducing the frictional force with other members, or imparting conductivity. Control agent, lubricant, conductive agent,
Various additives such as other resins can be contained. As a method for forming the charge adjusting layer 18, a mixture of the raw material resin and a coating liquid obtained by dissolving or dispersing various additives as necessary are subjected to conductive coating by a dipping method, a roll coater method, a doctor blade method, a spray method or the like. After coating on the elastic elastic layer, there is a method of drying at room temperature or at a temperature of about 50 to 170 ° C. and curing by crosslinking. When the mixture of the raw material resins is liquid, the support member 16c provided with the elastic layer 17c is set in a mold, and is molded and cured by a casting method, an injection molding method, or the like to form the charge adjusting layer 18. You can also. The thickness of this charge adjusting layer is 1 to 200
Although it can be set to about μm, a range of 5 to 100 μm is particularly preferable. If the thickness of the charge adjusting layer is too thin,
Since the charge amount of the developer is insufficient or the charge adjusting layer is worn, there is a possibility that a stable charge amount cannot be obtained over a long period of time. On the other hand, if the thickness is too large, the surface of the developer layer forming blade becomes hard, which damages the developer and causes the developer to adhere to the developer carrying roller or the developer layer forming blade, which causes image defects.

[0021]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, about the roller etc. obtained by the Example and the comparative example, the characteristic test was performed as follows. (1) Layer Thickness of Coating Layer A vertical section of the roller to be tested was observed and measured with a scanning electron microscope. (2) Solvent insolubility of the coating layer A glass plate was prepared separately from the roller to be tested, and the coating liquid used for forming the coating layer of each roller was applied to the glass plate. The coating film was heated and cured to prepare a coating film sample. After immersing this glass plate in a solvent similar to that used for preparing the coating liquid at room temperature for 24 hours,
After drying, the weight of the coating film before and after immersion is measured, the solvent insolubility is calculated by the following equation, and the solvent insolubility of the coating layer of the roller is determined. Whether the solvent insolubility of the coating layer is 70% by weight or more It was confirmed. Solvent insolubility = [(coating weight after immersion in solvent and drying) /
(Coating weight before immersion in solvent)] x 100 (% by weight)

(3) Surface roughness (Rz) For the roller to be tested, use a surface roughness meter Surfcom 590A.
(Manufactured by Tokyo Seimitsu Co., Ltd.) in a direction perpendicular to the axial direction (circumferential direction), measuring length 2.4 mm, measuring speed 0.3 mm /
sec. At a cutoff wavelength of 0.8 mm, JIS 10 point average roughness was obtained by averaging the values measured at 300 or more locations so that there was no deviation in the shaft direction and circumferential direction of the roller. (4) Specific resistance value A copper plate is prepared, and the coating solution is applied on the copper plate using the coating solution used for forming the coating layer of the developer carrying roller, and the coating is performed under the same conditions as the developer carrying roller. The film was heated and crosslinked and cured. Thereafter, the resistance between the copper plate and the measurement electrode was measured to obtain the specific resistance of the coating layer. (5) Resistance of Roller, etc. A load of 500 g was applied to both ends of the roller to be tested, pressed against a copper plate, and the resistance was measured by applying a voltage of 100 V using a resistivity meter R8340A (manufactured by Advantest). . (6) Cell diameter and number of cells Using a CCD video camera manufactured by Hilox Corporation,
Photographs were taken at a magnification of 1000 times, and the cell diameter and cell number of the image were measured.

Example 1 (Production of a developer carrying roller) Glycerin was added with propylene oxide and ethylene oxide to give a molecular weight of 500.
Polyether polyol (OH value: 33 mgK)
(OH / g) 100 parts (parts by weight, the same applies hereinafter), 1,4-butanediol 1.0 part, nickel acetylacetonate 0.5
, 0.01 parts of dibutyltin dilaurate and 2.0 parts of acetylene black were added and mixed using a mixer to prepare a polyol composition. The polyol composition was stirred and defoamed under reduced pressure, and then 17.5 parts of urethane-modified MDI (diphenylmethane diisocyanate) was added and stirred for 2 minutes. This was placed on a zinc-plated sulfur free-cutting steel shaft. And poured into a mold previously heated to 110 ° C.
After curing at 0 ° C. for 2 hours, a conductive elastic layer was formed on the outer periphery of the 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 10.5 μmRz. Next, as a silicone-modified alkyd resin, silicone alkyd varnish KR206 (manufactured by Shin-Etsu Chemical Co., Ltd., solid content: 50% by weight), and as a melamine resin, Super Beckamine L-145-60 (manufactured by Dainippon Ink and Chemicals, solid content ratio: 60% by weight), the above compound was mixed with a mixture of methyl ethyl ketone and toluene at a weight ratio of 90/10 as a solvent so as to have a solid content weight ratio of 50/50, and dispersed in a solvent in advance as a conductive agent. Carbon black # 220 (manufactured by Mikuni Dye Co., Ltd., solid content concentration: 40% by weight) was added so that the solid content was 30 parts by weight with respect to 100 parts by weight of the solid content of the above mixture, and dispersed to obtain a total solid content A coating solution having a concentration of 25% by weight was prepared. The conductive elastic roller was immersed in the coating liquid, pulled up, and heated at 110 ° C. for 4 hours to obtain a developer-carrying roller having a cured coating layer as shown in FIG. 2B. . The thickness of the coating layer of the developer carrying roller was about 1.5 μm, the solvent insolubility of the coating layer in methyl ethyl ketone was 89%, and the specific resistance value of the coating layer was 1.0 × 10 ¹⁴ Ω · cm. The surface roughness of the roller 4.7MyumRz, resistance of the rollers 10 ^7.1
Ω, hardness was Asker C hardness 70 °

(Preparation of a developer supply roller) 100 parts of a polyether polyol having an ethylene oxide content of 20% by weight and a molecular weight of 5,000 by adding propylene oxide and ethylene oxide to glycerin,
It was reacted with 25 parts of a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate in a weight ratio of 80:20 to obtain a prepolymer having an isocyanate content of 7.5% by weight. Next, 100 parts of this prepolymer, 1 part of N-methylmorpholine, 0.3 part of trimethylamine and 1.5 parts of a silicone-based surfactant were added, mixed, poured into a mold, and sealed. After 10 minutes, the pressure of the mold was released, and the polyurethane foam was taken out. A rectangular parallelepiped was cut out from the foam, a shaft hole was formed in the rectangular parallelepiped, and a zinc-plated sulfur free-cutting steel shaft coated with an adhesive was inserted into the hole, and heated to be bonded. Thereafter, the foam was ground using a grinder to obtain a developer supply roller similar to that of FIG. Roller hardness is 60 ° in Asker C hardness,
Resistance of the roller was 10 ^4.5 Ω. The average cell diameter of the foam was 600 μm, and the average number of cells was 55 cells / 25 m.
m, and the density was 0.11 g / cm ³ .

(Preparation of Developer Layer Forming Blade) Weight average molecular weight 1000 g 100 g of polytetramethylene ether glycol, 2,4-tolylene diisocyanate
50 g of a mixture having a weight ratio of 8: 2 with 6-tolylene diisocyanate was placed in a closed container, and sufficiently stirred.
It was kept at ° C. Stirring was repeated every 12 hours, and after 72 hours, the prepolymerization of polytetramethylene ether glycol was completed. The isocyanate content of the obtained prepolymer was 10.0% by weight. 100 parts of this prepolymer, 5.8 parts of 1,4-butanediol, 5.8 parts of trimethylolpropane, 0.01 parts of dibutyltin dilaurate
The parts were mixed and cast into a mold in which a stainless steel blade was previously disposed on the bottom surface to prepare a developer layer forming blade shown in FIG. 4A. The reaction equivalent ratio of NCO / OH was 1.1, and the curing conditions were a temperature of 70 ° C. for 3 hours. The hardness of the polyurethane elastic layer was 50 ° in JISA hardness.

(Image Forming Test by Developing Apparatus) The developer carrying roller, the developer supplying roller and the developer layer forming blade manufactured as described above are connected to the developing apparatus (non-magnetic one-component developing apparatus) of the image forming apparatus shown in FIG. And an image forming test. As a result, good images free of image defects such as image unevenness in the initial stage of printing and image fogging were obtained at any of room temperature / normal humidity, low temperature / low humidity, and high temperature / high humidity. Further, when a durability image test was performed on ordinary sheets up to 10,000 sheets at normal temperature / humidity, a good image free of image unevenness and image defects was obtained. Here, the conditions of normal temperature / normal humidity, low temperature / low humidity, and high temperature / high humidity are respectively 23 ° C.
/ 50%, 15 ° C / 10%, 32.5 ° C / 85% (the same applies hereinafter).

Comparative Example 1 In the developer layer forming blade of Example 1, the elastic layer was formed of silicone instead of polyurethane. The developer layer forming blade was manufactured as follows. Liquid A and Liquid B of silicone XE15-B5263 (manufactured by Toshiba Silicone Co., Ltd.) for LIM (Liquid Injection Molding) were mixed at a weight ratio of 1: 1, and a stainless steel support member was cast into a mold provided in advance. Thus, a developer layer forming blade shown in FIG. Curing condition is temperature 1
One minute at 30 ° C. The hardness of the silicone elastic layer is J
The ISA hardness was 50 °. The developer layer forming blade prepared as described above is used together with the same developer carrying row and developer supply roller as in Example 1 to the developing device (using a non-magnetic one-component developer) of the image forming apparatus shown in FIG. A built-in and image forming test was performed. As a result, in the initial stage of printing, at room temperature / normal humidity and at low temperature / low humidity, a good image without image defects such as image unevenness and image fogging was obtained, but at high temperature / high humidity, there was image fogging. Image unevenness occurred. Furthermore, when a durability image test was performed up to 10,000 sheets at normal temperature and normal humidity, the image fog was remarkable.
Further, image unevenness occurred.

[0028]

According to the developing device of the present invention, the main components constituting the developer carrying roller, the developer supply roller and the developer layer forming blade are made of polyurethane, so that various images can be obtained even when used continuously for a long period of time. It is possible to prevent the occurrence of defects and to reproduce a good image over a long period of time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an example of an electrophotographic image forming apparatus equipped with a developing device of the present invention.

FIG. 2 is a schematic sectional view illustrating an example of a developer carrying roller according to the present invention.

FIG. 3 is a schematic sectional view illustrating an example of a developer supply roller according to the present invention.

FIG. 4 is a schematic sectional view showing an example of a developer layer forming blade according to the present invention.

[Explanation of symbols]

 1: developing device 2: developer layer forming blade 3: developer supply roller 4: developer carrying roller 5: electrostatic latent image holder 6: transfer roller 7: cleaning device 8: cleaning blade 9: recording medium 10: development Agent 11: Shaft 12: Conductive elastic layer 13: Coating layer 14: Shaft 15: Elastic foam layer 16a: Support member 16b: Support member 16c: Support member 17a: Elastic layer 17b: Elastic layer 17c: Elastic layer 18: Charge adjustment layer

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[Procedure amendment]

[Submission date] September 24, 1999 (1999.9.2)
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 7

[Correction method] Change

[Correction contents]

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 2H077 AC04 AD06 AD13 AD23 AD35 FA01 FA13 FA22 FA26 FA27

Claims (10)

[Claims] An electrostatic latent roller having a developer supply roller for supplying a developer to an outer peripheral surface of the developer carrying roller; and a developer layer forming blade for forming a developer layer on the outer peripheral surface of the developer carrying roller. In a developing device for developing a visible image by attaching a developer carried on an outer peripheral surface of the developer carrying roller to an electrostatic latent image held on an image carrier, the developer carrying roller and the developer supply A developing device, wherein a main component of the roller and the developer layer forming blade is polyurethane. 2. A polyurethane as a main component, a developer carrying roller is a polyurethane elastic body having an Asker C hardness of 40 to 80 °, and a developer supply roller is an Asker F hardness of 30 to 80 °.
2. The developing device according to claim 1, wherein the 90 ° polyurethane foam and the developer layer forming blade are a polyurethane elastic body having a JISA hardness of 30 to 90 °. 3. The polyurethane elastic body constituting the developer carrying roller is a conductive elastic body and has a specific resistance of 10 ^3.
3. The developing device according to claim 2, wherein the developing device has a pressure of ¹⁰ to 10 ¹⁰ Ω · cm. 4. The polyurethane elastic body constituting the developer carrying roller has a surface roughness of 15 μm in JIS 10 point average roughness.
The developing device according to claim 2, wherein the developing device has a mRz or less. 5. A developer carrying roller in which a coating layer is formed on the outer periphery of the roller made of the polyurethane elastic material according to claim 2, wherein the coating layer has a specific resistance value of 10 ^9. 10 ¹⁶ Ω · cm and the surface roughness is JI
The S10 point average roughness is 10 μmRz or less.
5. The developing device according to any one of 4. 6. The polyurethane foam constituting the developer supply roller is a conductive foam, and has a specific resistance of 10 ^2.
3. The developing device according to claim 2, wherein the developing device has a resistance of from 10 to 10 ⁸ Ω · cm. 7. The polyurethane foam constituting the developer supply roller has a density of 0.03 to 0.5 g / cm ³ , an average cell diameter of 20 to 800 μm, and an average number of cells of 20 to 30 cells / 25.
7. The developing device according to claim 6, wherein the developing device is a single device. 8. The polyurethane elastic body constituting the developer layer forming blade is a conductive elastic body and has a specific resistance of 1
^3. The developing device according to claim 2, wherein the developing device has a density of 0 ² to 10 ⁸ Ω · cm. 9. The developing device according to claim 2, wherein the developer layer forming blade is formed by forming a charge adjusting layer on the layer made of the polyurethane elastic material according to claim 2. 10. An image forming apparatus comprising the developing device according to claim 1.