JP7501320B2 - Image forming apparatus and image forming method - Google Patents

Description

The present invention relates to an image forming apparatus and an image forming method.

In electrophotographic image forming devices such as copiers, printers, and facsimiles, cleaning blades are used to remove residual toner remaining on the surfaces of members to be cleaned, such as photoconductor drums (image carriers), photoconductor belts, intermediate transfer belts, and intermediate transfer drums. The cleaning blade presses its contact portion against the circumferential surface of the image carrier to scrape off and remove the toner remaining on the members to be cleaned.

As an example of a cleaning blade, there is a cleaning blade for an image forming device that contains an acrylic-modified polyorganosiloxane in the elastomer base material of the cleaning blade (see, for example, Patent Document 1).

However, Patent Document 1 does not state that the cleaning performance can be maintained even when an image forming apparatus equipped with a cleaning blade for an image forming apparatus is used for a long period of time in a high-temperature and high-humidity environment. Even when a cleaning blade is used in a state in which the image forming apparatus is installed in a high-temperature and high-humidity environment for a long period of time, it is necessary to be able to remove toner remaining on the image carrier and maintain the cleaning performance.

One aspect of the present invention aims to provide an image forming device that has excellent cleaning properties even in harsh environments.

One aspect of the image forming apparatus according to the present invention is an image forming apparatus that includes a member to be cleaned and a cleaning unit that removes toner remaining on the member to be cleaned, the cleaning unit includes a cleaning blade having an elastic member that comes into contact with the surface of the member to be cleaned to remove toner adhering to the surface of the member to be cleaned, the elastic member has a tip ridge portion that comes into contact with the member to be cleaned, the elastic member contains domains derived from a polysiloxane structure with an average dispersion diameter of 0.1 μm to 5.0 μm in a region from the surface including the tip ridge portion to a depth of 100 μm, and the toner contains 20% or more by number of particles with a particle diameter of 3 μm or less.

One aspect of the present invention is to provide an image forming device that has excellent cleaning properties even in harsh environments.

FIG. 2 is a perspective view illustrating a cleaning blade included in the image forming apparatus according to the embodiment. 4 is an explanatory diagram showing a state in which a cleaning blade included in the image forming apparatus according to the embodiment is in contact with the surface of a photoconductor; FIG. 1 is a diagram for explaining a region from the surface including the tip ridge line to a depth of 100 μm. 1 is a diagram for explaining a region from the surface including the tip ridge line to a depth of 100 μm. 1 is a diagram for explaining a region from the surface including the tip ridge line to a depth of 100 μm. 1 is a diagram for explaining a region from the surface including the tip ridge line to a depth of 100 μm. FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to an embodiment. FIG. 2 is a schematic diagram illustrating an example of an image forming unit included in the image forming apparatus.

The following describes in detail the embodiments of the present invention. Note that the embodiments are not limited to the following description, and can be modified as appropriate without departing from the gist of the present invention. In addition, in this specification, "to" indicating a numerical range means that the numerical values before and after it are included as the lower and upper limits, unless otherwise specified.

<Image forming apparatus>
The image forming apparatus according to one embodiment includes an image carrier which is a member to be cleaned, an electrostatic latent image forming unit which forms an electrostatic latent image on the image carrier, a developing unit which develops the electrostatic latent image with toner to form a visible image, a transfer unit which transfers the visible image to a recording medium, a fixing unit which fixes the transferred image transferred to the recording medium, and a cleaning unit which removes the toner remaining on the image carrier. Note that the image forming apparatus according to one embodiment may further include other configurations as necessary, such as a mechanism which applies a lubricant to the image carrier as a cleaning auxiliary unit.

In addition, the members to be cleaned include not only the photoreceptor drum (image carrier) but also the photoreceptor belt, intermediate transfer belt, intermediate transfer drum, etc., which are provided in the image forming device.

Below, when describing each component of the image forming device according to one embodiment, the cleaning unit will be described first.

[Cleaning section]
The cleaning unit is provided with a cleaning blade to remove toner remaining on the image carrier. The cleaning blade will now be described.

(Cleaning blade)
The cleaning blade is provided with an elastic member that comes into contact with the surface of a member to be cleaned to remove toner adhering to the surface of the member to be cleaned, the elastic member has a tip ridge portion that comes into contact with the member to be cleaned, the elastic member contains domains derived from a polysiloxane structure and having an average dispersed diameter of 0.1 μm to 5.0 μm in a region from the surface including the tip ridge portion to a depth of 100 μm, and the toner contains 20% or more by number of particles having a particle diameter of 3 μm or less.

Conventional cleaning blades have a problem that when placed in a high temperature (e.g., 40°C or higher) and high humidity (e.g., 70 RH or higher) environment for a long period of time, the elastic member that removes toner deteriorates, causing a decrease in sliding properties and a decrease in cleaning properties. The inventors focused on the size of the average dispersion diameter of the domain derived from the polysiloxane structure in a region of a predetermined depth from the surface including the tip ridge of the elastic member, and the content of particles of a predetermined size or less contained in the toner. The elastic member contains domains derived from the polysiloxane structure with an average dispersion diameter of 0.1 μm to 5.0 μm in a region from the surface including the tip ridge that contacts the member to be cleaned to a depth of 100 μm. And the toner contains 20% or more by number of particles with a particle diameter of 3 μm or less. It was found that the cleaning blade can thereby improve its resistance even in harsh environments such as high temperature and high humidity, and has excellent cleaning properties.

An example of a cleaning blade provided in an image forming apparatus according to one embodiment is shown in Figs. 1 and 2. Fig. 1 is a perspective view showing a cleaning blade, and Fig. 2 is an explanatory diagram showing a state in which the cleaning blade is in contact with the surface of a photoreceptor. As shown in Fig. 1, the cleaning blade 1 has an elastic member 2 and a support member 3. As shown in Fig. 2, the cleaning blade 1 is arranged so that an abutment portion 2d, which is one end on the free end side of the elastic member 2, abuts against the surface of the image carrier 4 along the longitudinal direction of the image carrier 4.

The elastic member 2 is formed in a rectangular shape, has a blade tip surface 2a, a blade underside surface 2b, and a tip ridge portion 2c, and has an abutment portion 2d that abuts against the surface of the image carrier 4. The abutment portion 2d is an area that includes the tip ridge portion 2c, and may include a part of at least one of the blade tip surface 2a and the blade underside surface 2b.

The blade tip surface 2a is the tip surface of the elastic member 2, and is the surface located on the upstream side A in the direction of travel of the image carrier 4 (the direction of rotation in FIG. 2).

The blade underside 2b is the main surface located on the downstream side B in the direction of travel of the image carrier 4 (the direction of rotation in FIG. 2).

The tip ridge 2c is the corner between the blade tip surface 2a and the blade underside 2b, and comes into contact with the surface of the image carrier 4. If the tip ridge 2c of the elastic member 2 is turned over, or if the linear pressure is high, parts of the blade tip surface 2a other than the corners can also become the tip ridge.

The upper blade surface 2e is the main surface of the elastic member 2 opposite the lower blade surface 2b.

The support member 3 is formed in a rectangular shape and is fixed to the end side of the blade upper surface 2e of the elastic member 2 with an adhesive or the like.

The cleaning blade has an elastic member, and may further have other members such as a support member, if necessary.

[Elastic member]
The elastic member abuts against the surface of the member to be cleaned to remove deposits adhering to the surface of the image carrier. The elastic member is disposed such that a contact portion including a tip ridge portion, which is one end of the free end side, abuts against the surface of the image carrier along the longitudinal direction.

The elastic member may have a single layer structure or a multi-layer structure (e.g., a two-layer structure). When the elastic member has a single layer structure, the elastic member is composed of a base material. When the elastic member has a multi-layer structure, the elastic member may have a base material and a surface layer.

The elastic member has a tip ridge.

The elastic member contains domains in a region from the surface, including the tip ridge, to a depth of 100 μm. The average dispersion diameter of the domains is 0.1 μm or more and 5.0 μm or less. The domains are derived from a polysiloxane structure. The elastic member may contain domains in locations other than the tip ridge.

The domain is derived from a polysiloxane structure. The polysiloxane structure is derived from, for example, a siloxane-based compound. The domain is formed, for example, by aggregation of siloxane-based compounds. In this case, the siloxane-based compound forming the domain may or may not be bonded to a matrix component.

A siloxane compound is a compound that has a siloxane bond, such as silicone. Silicones exist in the form of silicone oil, silicone resin, silicone grease, etc. Siloxane bonds have a higher bond energy than carbon bonds and can exist stably. Siloxane compounds have a low surface free energy and are excellent in release and lubricity.

The siloxane compound is preferably a compound made of silicone, and the silicone described below can be used.

The average dispersion diameter of the domains in the region from the surface, including the tip ridge, to a depth of 100 μm is 0.1 μm to 5.0 μm, and from the viewpoint of superior durability, it is preferably 0.5 μm to 2.0 μm.

The average dispersion diameter can be calculated by measuring the dispersion diameter of multiple domains (e.g., 100 or more) in a 100 μm area including any tip ridge line, and calculating the number average value.

For example, the cleaning blade is cut at any point to expose the cross section, and a 100 μm area including the tip ridge is photographed using a laser microscope or SEM, and the dispersion diameter is measured from the image. For the measurement, software such as ImagePro can be used to calculate the dispersion diameter from the binarized image.

At this time, it can be confirmed by using energy dispersive X-ray analysis (EDS) or the like that the domains in the observed image originate from the polysiloxane structure.

The region from the surface including the tip ridge to a depth of 100 μm is region Y at the corner between the blade tip surface 2a and the blade underside 2b of the elastic member 2, as shown in FIG. 3. Region Y contains a domain derived from the polysiloxane structure.

As shown in FIG. 4, the domains S derived from the polysiloxane structure may be distributed throughout the entire region Y, or as shown in FIG. 5, they may be distributed only in a part of the region Y. However, as shown in FIG. 5, when the domains S derived from the polysiloxane structure are distributed in a part of the region Y, it is preferable that the domains S derived from the polysiloxane structure are distributed on the surface side of the elastic member 2 in the region Y.

The elastic member 2 may have a single layer structure, as shown in FIG. 3, or a multi-layer structure.

When the elastic member 2 has a multi-layer structure, for example, as shown in FIG. 6, the elastic member 2 can have a two-layer structure of a base material 2-1 and a surface layer 2-2. In this case, the region from the surface including the tip ridge to a depth of 100 μm is present in the surface layer 2-2, and is region Y including the tip ridge 2-2c between the blade tip surface 2-2a and the blade underside 2-2b of the surface layer 2-2.

The Martens hardness HM of the elastic member at a position 20 μm deep from the surface of the tip ridge line when a load is 1000 μN is 0.5 N/mm ² or more and less than 1.5 N/mm ² , and preferably 0.8 N/mm ² to 1.2 N/mm ² .

The method for measuring Martens hardness HM is as follows:

For the measurement, for example, a microhardness tester HM-2000 manufactured by Fisher Instruments is used.

The Vickers indenter is pressed into the tip surface of the elastic member with a force of 1.0 mN for 10 seconds, held in place for 5 seconds, and then removed with a force of 1.0 mN for 10 seconds and measured.

The measurement location is 20 μm from the tip ridge of the underside of the elastic member.

The measurement method is to cut the tip of the elastic member to a width of about 1 cm, fix it to a slide glass or the like with adhesive or double-sided tape so that the bottom surface faces upwards, and measure a position 20 μm from the tip ridge of the bottom surface.

The elastic member contains, for example, a layer-constituting resin component and a domain component. The elastic member can contain domains derived from a polysiloxane structure dispersed in the layer-constituting resin component. The elastic member may have a sea-island structure in which the layer-constituting resin component is the sea and the domains formed by aggregation of the polysiloxane structure are the islands. The sea-island structure exists, for example, at least in a region from the surface including the tip ridge to a depth of 100 μm.

The layer-forming resin component and the domain component may or may not be bonded by a chemical bond.

In the elastic member, the area ratio of the domain in the cross section of region Y can be appropriately selected according to the purpose. The area ratio of the domain in the cross section of region Y is preferably 0.1% to 40%, and more preferably 0.5% to 30%, in order to maximize the effect of the elastic member.

The area ratio of the domain in the cross section of the region can be determined, for example, by the following method. The blade is cut at any point to expose the cross section, and a 100 μm area including the tip ridge is photographed with a laser microscope or SEM, and the area ratio of the siloxane compound is calculated from the image. The area ratio can be determined by calculating the area ratio from the binarized image using software such as ImagePro.

The average thickness of the elastic member can be selected appropriately depending on the purpose, and is preferably 1.0 mm to 3.0 mm or less, and more preferably 1.5 mm to 2.0 mm.

The average film thickness of the elastic member at the contact portion can be calculated by the arithmetic mean value of measurements taken at any 10 points on the elastic member at the contact portion.

The method for measuring the thickness of the elastic member at the contact portion can be appropriately selected depending on the purpose, and examples include a method of measuring the cut surface including the elastic member at the contact portion using a microscope. For example, the tip surface of the cleaning blade is turned upward and observed under a microscope to measure the thickness of the elastic member.

As described above, the elastic member can have a single layer structure or a multi-layer structure.

When the elastic member has a single-layer structure, the elastic member can be composed of only a substrate, and the substrate can be obtained, for example, by curing the following composition for forming an elastic member.

(Composition for forming elastic member)
The composition for forming the elastic member is, for example, a first composition in an emulsified state containing a curing agent made of an active hydrogen compound.

((First Composition))
The first composition contains at least one of the following components A and B, and also a component C.
Component A: NCO-terminated modified silicone prepolymer Component B: Silicone oil Component C: NCO-terminated urethane prepolymer

-Component A: NCO-terminated silicone prepolymer-
The NCO-terminated modified silicone prepolymer is a prepolymer having isocyanate groups at the ends, which is obtained by reacting a modified silicone having at least one hydroxyl group at the end with a first polyisocyanate.

Modified silicone is a silicone that has at least one hydroxyl group at the end, and commercially available products can be used.

The modified silicone is selected from those capable of reacting with the first polyisocyanate to form a prepolymer having an NCO group at the end. Specifically, from the standpoint of stability, hydroxyl-modified silicones having hydroxyl or amino groups at the end are more preferable.

Commercially available products include KF-6000, KF-6001, KF-6002, KF-6003, X-22-176F, X-22-176DX, and X-22-176GX-A (Shin-Etsu Silicones). Modifications at the ends include one end, both ends, and side chains, but as described below, one end modification is more desirable in terms of the efficiency of functioning as a surfactant.

The first polyisocyanate is a compound that is bonded to the end of the modified silicone via a urethane bond and has an isocyanate group (NCO) at the end; details will be given later.

The NCO-terminated modified silicone prepolymer is a silicone prepolymer having an NCO group at the end, obtained by reacting a modified silicone with a first polyisocyanate. It can be obtained by mixing about twice the equivalent amount of the first polyisocyanate of the functional group on the modified silicone side, and heating and stirring.

-Component B: Silicone oil-
The silicone oil is a silicone oil (organopolysiloxane) that is liquid at room temperature, and commercially available products can be used.

As the silicone oil, a general polyorganosiloxane can be used. Since the silicone oil is stably dispersed in the polyurethane/urea matrix, it is more preferable that it has poor compatibility with the matrix, and such a silicone oil is dispersed in an emulsified state in an NCO-terminated urethane prepolymer, for example, using an NCO-terminated modified silicone prepolymer as a surfactant. Dimethyl silicone is the most preferred. Dimethyl silicone oil is the most versatile silicone oil, and commercially available products from various companies can be used. Note that, when emulsifying as described above, a higher viscosity requires more energy, so a silicone oil with a viscosity of about 1 to 10,000 mPa·s/25°C is preferably used.

-Component C: NCO-terminated urethane prepolymer-
The NCO-terminated urethane prepolymer is a prepolymer having an isocyanate group at the end, which is obtained by reacting a polyol with a second polyisocyanate.

The polyol is, for example, a polyol with a molecular weight of 500 to 4000, and is a so-called long-chain polyol used in the production of polyurethane resin. Polyester polyol, polyether polyol, polycarbonate polyol, etc. are preferably used.

The second polyisocyanate is a compound that reacts with the terminal hydroxyl groups of the polyol to bond through urethane bonds, resulting in an isocyanate group (NCO) at the end.

The polyisocyanate compounds used as the first polyisocyanate and the second polyisocyanate include, for example, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-methoxy-4,4'-diphenyl diisocyanate, 3,3'-dimethyldiphenyl diisocyanate, 1,1'-dimethyl-2,2'- ... Examples include 4,4'-dimethylmethane diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexylmethane 4,4'-diisocyanate, cyclohexylene-1,2-diisocyanate, and cyclohexylene-1,4-diisocyanate.

The first and second polyisocyanates are preferably selected so that the first polyisocyanate has a higher reactivity with the curing agent than the second polyisocyanate. The reactivity of the isocyanate group (R-NCO) increases as the electron-withdrawing property of the substituent R increases. Specifically, the reactivity of aromatic polyisocyanates is greater than that of aliphatic polyisocyanates, and the reactivity decreases due to steric hindrance such as methyl groups in the side chains. These can be inferred from the following urethane-related literature:

Hepburn, C. : Polyurethane Elastomers, Applied Science Publishers, (1982)
・Saunders J. H. , Frisch K. C. : Polyurethanes: Chemistry and technology, Part 1. Chemistry, New York: Interscience Publishers, 170 (1962)
・Polyurethane Resin Handbook, edited by Keiji Iwata, Nikkan Kogyo Shimbun (1987)
・Curing Agents for Polyurethane Resin Paints, Yoshiaki Takanaka, Journal of the Japan Color Materials Association, 49 (1976)

In this way, aromatic polyisocyanates generally have a higher reactivity with curing agents than aliphatic or alicyclic polyisocyanates, so for example, the first polyisocyanate may be an aromatic polyisocyanate and the second polyisocyanate may be an aliphatic or alicyclic polyisocyanate. Both may be aromatic polyisocyanates, or both may be aliphatic or alicyclic polyisocyanates.

Specifically, for example, an aromatic polyisocyanate can be used as the first polyisocyanate, and an aliphatic polyisocyanate can be used as the second polyisocyanate. In addition, both can be selected from aromatic polyisocyanates or aliphatic polyisocyanates. For example, a combination of xylylene diisocyanate (high aliphatic reactivity) as the first polyisocyanate and dicyclohexylmethane 4,4'-diisocyanate (low aliphatic reactivity) as the second polyisocyanate can be exemplified.

The NCO-terminated urethane prepolymer is the main component that forms the matrix of the urethane resin cured product, and can be appropriately synthesized or selected from commercially available products depending on the desired physical properties. For example, it can be obtained by mixing a long-chain polyol such as polyester polyol, polyether polyol, or polycarbonate polyol, which has a molecular weight of 500 to 4000, with a second polyisocyanate in an amount about twice the equivalent of the hydroxyl groups on the polyol side, and heating and stirring. As long as the requirement of the relative reactivity of the NCO-terminated modified silicone prepolymer with the first polyisocyanate is met, it can be selected from commercially available products.

The first composition contains at least one of component A and component B, and component C, and it is preferable that they are in an emulsified state when mixed together. That is, the NCO-terminated silicone prepolymer of component A acts as a surfactant, and can hold the silicone oil of component B in an emulsified state in the NCO-terminated urethane prepolymer of component C. The NCO-terminated silicone prepolymer coordinates around the fine particles of silicone oil to form micelles, which become an emulsion dispersed in the NCO-terminated urethane prepolymer.

As described above, the first composition can be an emulsion in which an NCO-terminated urethane prepolymer is dispersed with an NCO-terminated modified silicone prepolymer and silicone oil using, for example, a dispersing device.

As a dispersion device, a general emulsification device such as a high-speed mixer or homogenizer can be used.

By dispersing the NCO-terminated modified silicone prepolymer in the NCO-terminated urethane prepolymer and then dispersing the silicone oil, a uniform milky white dispersion can be quickly produced.

((hardening agent))
The curing agent is an active hydrogen-containing compound reactive with NCO groups, specifically a polyhydric hydroxy compound or a polyamine compound. When a polyhydric hydroxy compound is used as a curing agent, the matrix resin (layer-constituting resin) becomes a polyurethane resin, and when a polyamine is used as a curing agent, the matrix resin becomes a polyurethane urea resin. Since it is effective to rapidly advance the reaction between the NCO-terminated silicone prepolymer that becomes the shell and the curing agent, a curing agent containing a polyamine having an NCO equivalent or more of the silicone prepolymer is more preferably used. The polyhydric hydroxy compound may be used together with a polyamine compound as a chain extender. In addition, in order to appropriately advance the curing reaction, a known urethane curing catalyst (amines, organometallics) may also be used in combination.

Here, aliphatic polyhydric alcohols are preferably used as polyhydric hydroxy compounds, and examples of such compounds include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,4-cyclohexanedimethanol, 1,4-bis(hydroxyethoxy)benzene, and 1,3-bis(hydroxyethoxy)benzene.

Examples of polyamine compounds include 4,4'-methylenebis(2-chloroaniline), diethyltoluenediamine, and dimethylthiotoluenediamine.

The elastic member-forming composition is thermally cured in a specified mold or the like to become either or both of a cured polyurethane resin and a cured urea resin.

The composition for forming elastic members contains an NCO-terminated silicone prepolymer, an NCO-terminated urethane prepolymer, and a curing agent that is an active hydrogen-containing compound that is reactive with NCO groups, and a polyurethane resin cured product is formed by reacting the NCO groups with the curing agent.

It is preferable to use a first polyisocyanate that is added to the end of the NCO-terminated silicone prepolymer and a second polyisocyanate that is added to the end of the NCO-terminated urethane prepolymer, the first polyisocyanate being more reactive to the curing agent than the second polyisocyanate. In that case, the NCO-terminated silicone prepolymer that forms the micelle reacts with the curing agent first, forming a core-shell structure in which the silicone oil becomes the core and the cured product of the NCO-terminated silicone prepolymer becomes the shell. That is, when the NCO-terminated silicone prepolymer that forms the micelle reacts with the curing agent first, a pseudo-capsule in which the silicone oil is fixed in the micelle is generated. After that, the NCO-terminated urethane prepolymer that forms the matrix reacts with the curing agent and cures, resulting in a cured urethane resin in which the core-shell structure is stably dispersed in either or both of the urethane matrix and the urea matrix.

When the elastic member has a multi-layer structure, the elastic member can have a base material and a surface layer.

(Base material)
The substrate is not particularly limited in terms of shape, material, size, structure, etc., and can be appropriately selected depending on the purpose.

Examples of shapes include flat plates, strips, sheets, etc.

There are no particular limitations on the size, and it can be selected appropriately depending on the size of the item to be cleaned.

The material for the substrate can be appropriately selected depending on the purpose, and the above-mentioned elastic substrate forming composition can be used. In addition, polyurethane rubber, polyurethane elastomer, etc. are suitable as the material for the substrate because they are easy to obtain high elasticity.

The shape of the substrate can be, for example, a shape consisting of a pair of plate surfaces that face each other in the thickness direction of the substrate, and two pairs of end surfaces that are perpendicular to the plate surfaces and face each other in the in-plane direction of the plate surfaces.

The structure of the substrate can be appropriately selected depending on the purpose, and examples include a single-layer structure made of one material, a two-layer structure made of two different materials molded together, and a multi-layer structure made of several different materials molded together.

When manufacturing a substrate made up of two or more laminated layers, it is possible to mold the layers together in an integrated manner without delamination by continuously injecting raw materials with different mixture ratios into a centrifugal molding die before each layer has completely hardened.

The method for manufacturing the substrate can be appropriately selected depending on the purpose. For example, a polyurethane prepolymer is prepared using a polyol compound and a polyisocyanate compound, and a curing agent and, if necessary, a curing catalyst are added to the polyurethane prepolymer, followed by crosslinking in a specified mold. The product that has been post-crosslinked in an oven is molded into a sheet by centrifugal molding, and is then left to mature at room temperature and cut into a plate of specified dimensions. This is used to manufacture the substrate.

There are no particular limitations on the polyol compound, and it can be appropriately selected depending on the purpose. For example, high molecular weight polyols, low molecular weight polyols, etc. can be mentioned.

Examples of high molecular weight polyols include polyester polyols, which are condensates of alkylene glycols and aliphatic dibasic acids; polyester polyols such as ethylene adipate ester polyol, butylene adipate ester polyol, hexylene adipate ester polyol, ethylene propylene adipate ester polyol, ethylene butylene adipate ester polyol, and ethylene neopentylene adipate ester polyol, which are polyester polyols of alkylene glycols and adipic acid; polycaprolactone polyols such as polycaprolactone ester polyol obtained by ring-opening polymerization of caprolactone; and polyether polyols such as poly(oxytetramethylene) glycol and poly(oxypropylene) glycol. These may be used alone or in combination of two or more.

Examples of low molecular weight polyols include dihydric alcohols such as 1,4-butanediol, ethylene glycol, neopentyl glycol, hydroquinone-bis(2-hydroxyethyl)ether, 3,3'-dichloro-4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenylmethane; and trihydric or higher polyhydric alcohols such as 1,1,1-trimethylolpropane, glycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, trimethylolethane, 1,1,1-tris(hydroxyethoxymethyl)propane, diglycerin, and pentaerythritol. These may be used alone or in combination of two or more.

The polyisocyanate compound can be appropriately selected depending on the purpose, and examples thereof include methylene diphenyl diisocyanate (MDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), naphthylene 1,5-diisocyanate (NDI), tetramethyl xylene diisocyanate (TMXDI), isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate (H6XDI), dicyclohexylmethane diisocyanate (H12MDI), hexamethylene diisocyanate (HDI), dimer acid diisocyanate (DDI), norbornene diisocyanate (NBDI), trimethylhexamethylene diisocyanate (TMDI), etc. These may be used alone or in combination of two or more.

The curing catalyst can be selected appropriately depending on the purpose, and examples include 2-methylimidazole, 1,2-dimethylimidazole, etc.

The content of the curing catalyst can be appropriately selected depending on the purpose, and is preferably 0.01% by mass to 0.5% by mass, and more preferably 0.05% by mass to 0.3% by mass.

The JIS-A hardness of the substrate can be appropriately selected depending on the purpose, and is preferably 60 degrees or more, and more preferably 65 degrees to 80 degrees. If the JIS-A hardness is 60 degrees or more, it is easier to obtain blade line pressure, and the area of contact with the image carrier is less likely to expand, making cleaning defects less likely to occur.

Here, the JIS-A hardness of the substrate can be measured, for example, using a micro rubber hardness meter MD-1 manufactured by Kobunshi Keiki Co., Ltd.

The resilience modulus of the substrate in accordance with JIS K6255 can be appropriately selected depending on the purpose. The resilience modulus of the substrate can be measured, for example, in accordance with JIS K6255 at 23°C using a Toyo Seiki Seisakusho No. 221 resilience tester.

The average thickness of the substrate is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 1.0 mm or more and 3.0 mm or less.

(Surface layer)
The surface layer is obtained, for example, by curing the above-mentioned elastic member-forming composition. In the case where the elastic member has a surface layer and a substrate, the surface layer has a tip ridge portion. The surface layer contains domains derived from a polysiloxane structure, with an average dispersion diameter of 0.1 μm to 5.0 μm, in a region from the surface including the tip ridge portion to a depth of 100 μm. Furthermore, the Martens hardness HM of the surface layer at a position 20 μm deep from the surface of the tip ridge portion is 0.5 N/mm ² to less than 1.5 N/mm ² under a load of 1000 μN.

The average thickness of the surface layer can be appropriately selected depending on the purpose, and is preferably 30 μm to 800 μm, and more preferably 50 μm to 500 μm. If the average thickness is 50 μm or more, even if it wears down during long-term use, the surface exposed after wear also contains domains derived from the polysiloxane structure, and even if it wears down, the part in contact with the photoreceptor always has domains derived from the polysiloxane structure, making it possible to maintain a low coefficient of friction. If the average thickness is 500 μm or less, deterioration of dimensional accuracy during processing due to the influence of a surface layer containing domains derived from the polysiloxane structure can be further suppressed.

<Support Member>
The cleaning blade may have a support member. The support member is preferably connected to one end of the elastic member so as to have a free end of a predetermined length at the other end.

There are no particular restrictions on the shape, size, material, etc. of the support member, so long as it is a member that supports the elastic member, and it can be selected appropriately depending on the purpose.

Examples of the shape of the support member include a flat plate, a strip, a sheet, etc.

The size of the support member can be selected appropriately depending on the size of the member to be cleaned.

Materials for the support member include metal, plastic, ceramics, etc. Among these, metal plates are preferred from the standpoint of strength, and steel plates such as stainless steel, aluminum plates, and phosphor bronze plates are particularly preferred.

[toner]
The toner contains 20% or more by number of particles having a particle diameter of 3 μm or less. Since particles having a particle diameter of 3 μm or less have a large specific surface area, they greatly affect the adhesive force. By keeping the ratio of particles having a particle diameter of 3 μm or less within the above range, the adhesive force between the toner particles in the cleaning nip is increased, and foreign matter on the member to be cleaned is easily scraped off by the toner and the cleaning blade.

The cleaning blade contains a domain of polysiloxane, and the amount of polysiloxane is always greater near the contact portion, including the ridge at the tip of the elastic member. Therefore, if the ratio of particles with a particle diameter of 3 μm or less in the toner is 20% or more by number, the particles of 3 μm or less will aggregate with the polysiloxane near the contact portion to form a strong dam layer. In addition, since the cleaning blade has very high sliding properties, the position of the cleaning blade is always stable, and this dam layer can be maintained for a long time. This makes it possible to scrape off toner and other deposits on the image carrier even under harsh conditions.

The method for measuring the particle size is not particularly limited, and any suitable measuring method can be used using a precision particle size distribution measuring device or the like. As a precision particle size distribution measuring device, a Coulter Multisizer III (manufactured by Coulter, Inc.) or the like can be used. An example of a method for measuring the particle size is shown below.

First, a small amount of surfactant is added to the electrolyte as a dispersant. The electrolyte may be, for example, an aqueous solution prepared by using first-class sodium chloride to prepare an approximately 1% NaCl aqueous solution. The measurement sample is added as a solid to the mixture of the electrolyte and surfactant to obtain an electrolyte volume in which the sample is suspended. The electrolyte in which the sample is suspended is dispersed for several minutes using an ultrasonic disperser, and the volume and number of toner particles are measured using an aperture on a precision particle size distribution measuring device to calculate the volume distribution and number distribution. The volume average particle diameter Dv and number average particle diameter Dp of the toner are obtained from the obtained distribution. The particle diameter of the toner can be determined based on at least one of the volume average particle diameter Dv and number average particle diameter Dp.

Next, the percentage of particles with a particle diameter of 3 μm or less can be calculated for particles with a particle diameter within a predetermined range (e.g., 2.00 μm or more and less than 40.30 μm) calculated based on at least one of the volume average particle diameter Dv and the number average particle diameter Dp. The "percentage of particles with a particle diameter of 3 μm or less" refers to the number percentage (number %) of particles with a particle diameter of 3.00 μm or less. The number percentage of particles with a particle diameter of 3.00 μm or less refers to the ratio of the number of particles with a particle diameter within a predetermined range (e.g., 2.00 μm or more and less than 40.30 μm) to the number of particles with a particle diameter of 3.00 μm or less. For example, when particles with a particle diameter of 2.00 μm or more and less than 40.30 μm are targeted, the "proportion of particles with a particle diameter of 3 μm or less" may be the number proportion (number %) of particles less than 3.17 μm, which is the ratio of the number of particles with a particle diameter of less than 3.17 μm to the number of particles with a particle diameter of 2.00 μm or more and less than 40.30 μm.

In this case, 13 channels can be used to distribute particles, for example, 2.00 μm or more and less than 2.52 μm; 2.52 μm or more and less than 3.17 μm; 3.17 μm or more and less than 4.00 μm; 4.00 μm or more and less than 5.04 μm; 5.04 μm or more and less than 6.35 μm; 6.35 μm or more and less than 8.00 μm; 8.00 μm or more and less than 10.08 μm; 10.08 μm or more and less than 12.70 μm; 12.70 μm or more and less than 16.00 μm; 16.00 μm or more and less than 20.20 μm; 20.20 μm or more and less than 25.40 μm; 25.40 μm or more and less than 32.00 μm; and 32.00 μm or more and less than 40.30 μm.

The toner preferably contains 25% to 55% by number of particles with a particle diameter of 3 μm or less, and more preferably 30% to 50% by number. If the number of particles with a particle diameter of 3 μm or less exceeds 55% by number, the charge distribution of the toner deteriorates, resulting in quality issues such as scattering. If the content ratio of particles with a particle diameter of 3 μm or less is within the above preferred range, a stronger dam layer can be maintained for a longer period of time, and the toner on the image carrier can be scraped off more reliably.

The toner contains a binder resin as a binding resin, and may contain other components such as a colorant and a release agent as necessary.

(Binder resin)
The binder resin may be a binder resin used for full-color toner. Examples of the binder resin that may be used include polyester resins, (meth)acrylic resins, styrene-(meth)acrylic copolymer resins, epoxy resins, and cyclic olefin resins (COC (e.g., TOPAS-COC (manufactured by Ticona))). From the viewpoint of stress resistance in a developing device, it is preferable to use polyester resins.

A polyester resin that is preferably used is a polyester resin obtained by polycondensation of a polyhydric alcohol component and a polycarboxylic acid component. Among the polyhydric alcohol components, examples of the dihydric alcohol component include bisphenol A alkylene oxide adducts such as polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (3,3)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (6)-2,2-bis(4-hydroxyphenyl)propane, and polyoxyethylene (2,0)-2,2-bis(4-hydroxyphenyl)propane, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polytetramethylene glycol, bisphenol A, and hydrogenated bisphenol A. Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

Among the polycarboxylic acid components, examples of dicarboxylic acid components include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinic acid, isooctylsuccinic acid, n-octylsuccinic acid, isooctylsuccinic acid, and anhydrides or lower alkyl esters of these acids.

Examples of trivalent or higher carboxylic acid components include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, anhydrides of these acids, and lower alkyl esters.

In addition, a resin obtained by carrying out a condensation polymerization reaction to obtain a polyester resin and a radical polymerization reaction to obtain a vinyl resin in parallel in the same vessel using a mixture of raw material monomers for a polyester resin, raw material monomers for a vinyl resin, and a monomer that reacts with the raw material monomers for both resins (hereinafter simply referred to as a "vinyl polyester resin") can also be suitably used as a polyester resin. In addition, a monomer that reacts with raw material monomers for both resins is, in other words, a monomer that can be used in both condensation polymerization reactions and radical polymerization reactions. In other words, it is a monomer that has a carboxy group that can undergo condensation polymerization reaction and a vinyl group that can undergo radical polymerization reaction, and examples of such monomers include fumaric acid, maleic acid, acrylic acid, and methacrylic acid.

Examples of raw material monomers for polyester resins include the polyhydric alcohol components and polyvalent carboxylic acid components described above. Examples of raw material monomers for vinyl resins include styrene or styrene derivatives such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, and p-chlorostyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; methyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, neopentyl methacrylate, 3-(methyl)butyl methacrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, undecyl methacrylate, and dodecyl methacrylate. acrylate alkyl esters such as methyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, neopentyl acrylate, 3-(methyl)butyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, etc.; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, etc.; acrylonitrile, maleic acid esters, itaconic acid esters, vinyl chloride, vinyl acetate, vinyl benzoate, vinyl methyl ethyl ketone, vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. Examples of polymerization initiators used when polymerizing raw material monomers for vinyl resins include azo or diazo polymerization initiators such as 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and peroxide polymerization initiators such as benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, and lauroyl peroxide.

As the binder resin, the various polyester resins described above are preferably used, but from the viewpoint of further improving the separation property and offset resistance as an oil-less fixing toner, it is more preferable to use the first binder resin and the second binder resin shown below.

The first binder resin is a polyester resin obtained by polycondensing the above-mentioned polyhydric alcohol component and polycarboxylic acid component, in particular, a polyester resin obtained by using a bisphenol A alkylene oxide adduct as the polyhydric alcohol component and terephthalic acid and fumaric acid as the polycarboxylic acid component.

The second binder resin is a vinyl polyester resin, in particular a vinyl polyester resin obtained by using bisphenol A alkylene oxide adduct, terephthalic acid, trimellitic acid, and succinic acid as raw monomers for the polyester resin, styrene and butyl acrylate as raw monomers for the vinyl resin, and fumaric acid as a bireactive monomer.

The hydrocarbon wax may be added when synthesizing the first binder resin. To add the hydrocarbon wax to the first binder resin in advance, the first binder resin may be synthesized in a state where the hydrocarbon wax is added to the monomer for synthesizing the first binder resin. For example, the condensation polymerization reaction may be performed in a state where the hydrocarbon wax is added to the acid monomer and the alcohol monomer that constitute the polyester resin as the first binder resin. In the case where the first binder resin is a vinyl polyester resin, the hydrocarbon wax may be added to the raw material monomer of the polyester resin, and the raw material monomer of the vinyl resin may be dropped into the monomer while stirring and heating the monomer, to perform the polycondensation reaction and the radical polymerization reaction.

(wax)
In general, the lower the polarity of the wax, the better the releasability from the fixing roller. The wax used in this embodiment is a hydrocarbon wax with low polarity, which dissolves in hexane. The amount of wax added is preferably 3.0% to 10.0% relative to 100% by mass of the toner, and more preferably 4.0% to 8.0%.

(Wax Dispersant)
The toner of the present invention may contain a wax dispersant that aids in dispersing the wax.

The wax dispersant is not particularly limited, and known dispersants can be used. Examples of wax dispersants include polymers and oligomers in which a unit highly compatible with wax and a unit highly compatible with resin exist as a block body, polymers or oligomers in which one of a unit highly compatible with wax and a unit highly compatible with resin is grafted to the other, copolymers of unsaturated hydrocarbons such as ethylene, propylene, butene, styrene, α-styrene, etc., and α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, etc., or esters or anhydrides thereof, and block or graft bodies of vinyl resins and polyesters.

Units that are highly compatible with the above waxes include long-chain alkyl groups with 12 or more carbon atoms, polyethylene, polypropylene, polybutene, polybutadiene, and copolymers thereof.

Examples of units that are highly compatible with the above resins include polyester and vinyl resins.

(Coloring Agent)
As the colorant, pigments and dyes used as colorants for full-color toners can be used.As the colorant, for example, carbon black, aniline blue, chalcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, copper phthalocyanine, malachite green oxalate, lamp black, rose bengal, C.I. Pigment Red 48:1, C.I. Pigment Red 122, C.I. Pigment Red 57:1, C.I. Pigment Red 184, C.I. Pigment Yellow 97, C.I. Pigment Yellow 12, C.I. Pigment Yellow 17, C.I. Pigment Yellow 74, C.I. Solvent Yellow 162, C.I. Pigment Yellow 180, C.I. Pigment Yellow 185, C.I. Examples of suitable pigments include C.I. Pigment Blue 15:1, C.I. Pigment Blue 15:3, and the like.

The content of the colorant in the toner particles is preferably in the range of 2 to 15 parts by mass per 100 parts by mass of the total binder resin. From the viewpoint of dispersibility, it is preferable that the colorant is used in the form of a master batch in which the colorant is dispersed in a mixed binder resin of the first binder resin and the second binder resin used. The amount of the master batch added may be such that the amount of the colorant contained falls within the above range. The colorant content in the master batch is preferably 20% to 40% by mass.

(Charge control agent)
As the charge control agent, a general charge control agent used in full-color toners can be used.

Charge control agents include, for example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus elements or compounds, tungsten elements or compounds, fluorine-based activators, metal salts of salicylic acid, and metal salts of salicylic acid derivatives. Specifically, the nigrosine dye Bontron 03, the quaternary ammonium salt Bontron P-51, the metal-containing azo dye Bontron S-34, the oxynaphthoic acid metal complex E-82, the salicylic acid metal complex E-84, the phenol condensate E-89 (all manufactured by Orient Chemical Industry Co., Ltd.), the quaternary ammonium salt molybdenum complexes TP-302 and TP-415 (all manufactured by Hodogaya Chemical Co., Ltd.), the quaternary ammonium salt Copy Charge PSY VP2038, the triphenylmethane derivative Copy Blue PR, the quaternary ammonium salt Copy Charge NEG VP2036, and Copy Charge NX. Examples include VP434 (all manufactured by Hoechst), LRA-901, the boron complex LR-147 (manufactured by Nippon Carlit), copper phthalocyanine, perylene, quinacridone, azo pigments, and other polymeric compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. Of these, substances that control the toner to a negative polarity are particularly preferred.

The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner manufacturing method, including the dispersion method, and is not limited to a specific amount, but is preferably used in the range of 0.1 to 10 parts by weight per 100 parts by weight of binder resin. The range of 0.2 to 5 parts by weight is more preferable.

(External additives)
In the present invention, inorganic fine particles can be used as an external additive to aid flowability and developability.

Specific examples of inorganic fine particles include silicon oxide, zinc oxide, tin oxide, silica sand, titanium oxide, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

Toner can be produced by a variety of methods, including polymerization and pulverization.

Next, we will explain each component of the image forming device other than the cleaning unit.

[Image Carrier]
The material, shape, structure, size, etc. of the image carrier (sometimes called electrostatic latent image carrier, electrophotographic photoreceptor, or photoreceptor) are not particularly limited and can be appropriately selected from known materials. Examples of materials for the image carrier include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors (OPC) such as polysilane and phthalopolymethine. Among these, amorphous silicon is preferred in terms of long life.

For example, an amorphous silicon photoreceptor can be made by heating a support to 50°C to 400°C and forming a photoconductive layer made of a-Si on the support by a deposition method such as vacuum deposition, sputtering, ion plating, thermal CVD (Chemical Vapor Deposition), photo-CVD, or plasma CVD. Among these, the plasma CVD method, in other words, the method of decomposing a raw material gas by direct current, high frequency, or microwave glow discharge to form an a-Si deposition film on the support, is preferred.

The shape of the image carrier is not particularly limited and can be selected appropriately depending on the purpose, but a cylindrical shape is preferred. The outer diameter of the cylindrical image carrier is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 3 mm to 100 mm, more preferably 5 mm to 50 mm, and particularly preferably 10 mm to 30 mm.

[Electrostatic latent image forming unit]
The electrostatic latent image forming unit is not particularly limited as long as it is a means for forming an electrostatic latent image on an image carrier, and can be appropriately selected according to the purpose. The electrostatic latent image forming unit includes, for example, a charging device (charger) that uniformly charges the surface of the image carrier, and an exposure device (exposure device) that imagewise exposes the surface of the image carrier.

The charger is not particularly limited and can be appropriately selected depending on the purpose, but examples include contact chargers equipped with conductive or semiconductive rolls, brushes, films, rubber blades, etc., and non-contact chargers that use corona discharge such as corotrons and scorotrons.

The shape of the charger can be any shape, such as a roller, magnetic brush, fur brush, etc., and can be selected according to the specifications and shape of the image forming device.

The charger is preferably one that is arranged in contact or non-contact with the image carrier and charges the surface of the image carrier by applying superimposed DC and AC voltages. It is also preferable that the charger is a charging roller that is arranged in close proximity to the image carrier but not in contact with it via a gap tape, and that the charger charges the surface of the image carrier by applying superimposed DC and AC voltages to the charging roller.

The charger is not limited to a contact type charger, but it is preferable to use a contact type charger because it results in an image forming apparatus that generates less ozone from the charger.

The exposure device is not particularly limited as long as it can expose the surface of the image carrier charged by the charger in the shape of the image to be formed, and can be appropriately selected depending on the purpose. Examples of exposure devices include a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system.

The light source used in the exposure device is not particularly limited and can be selected appropriately depending on the purpose. Examples include fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light-emitting diodes (LEDs), semiconductor lasers (LDs), electroluminescence (EL), and other light-emitting materials in general.

In addition, various filters such as sharp cut filters, band pass filters, near infrared cut filters, dichroic filters, interference filters, and color temperature conversion filters can be used to irradiate only light in the desired wavelength range.

It is also possible to use a backlight system in which exposure is performed imagewise from the back side of the image carrier.

[Development section]
The developing unit is not particularly limited as long as it can develop the electrostatic latent image formed on the image carrier to form a toner image, and can be appropriately selected according to the purpose. For example, the developing unit can be suitably used one that contains toner and has a developing device that can apply the toner to the electrostatic latent image in a contact or non-contact manner, and a developing device equipped with a toner container is preferable.

The developing device may be a single-color developing device or a multi-color developing device. As the developing device, for example, a developing device having an agitator that charges the toner by friction agitation, a magnetic field generating unit fixed inside, and a rotatable developer carrier that carries developer containing toner on its surface is preferable.

Five developing units may be provided. The developing units are provided with black, cyan, magenta, and yellow color toners, and the toner according to an embodiment. The toner according to an embodiment may be of any color, but is preferably colorless or white. The developing units may also use some or all of the black, cyan, magenta, and yellow color toners as the toner according to an embodiment.

[Transfer section]
The transfer section preferably has a first transfer section that transfers a toner image onto an intermediate transfer body to form a composite transfer image, and a second transfer section that transfers the composite transfer image onto a recording medium. The intermediate transfer body is not particularly limited and can be appropriately selected from known transfer bodies depending on the purpose, and a transfer belt or the like is preferably used.

It is preferable that the transfer section (primary transfer means and secondary transfer section) has at least a transfer device that peels and charges the toner image formed on the image carrier (photoconductor) onto the recording medium. There may be one transfer section, or two or more transfer sections.

Examples of transfer devices include corona transfer devices that use corona discharge, transfer belts, transfer rollers, pressure transfer rollers, adhesive transfer devices, etc.

The recording medium is typically plain paper, but there are no particular limitations as long as it is capable of transferring the unfixed image after development, and can be selected appropriately according to the purpose. A PET base for overhead projectors can also be used.

[Fuser unit]
The fixing unit is not particularly limited and can be appropriately selected depending on the purpose, but a known heating and pressurizing unit is suitable. Examples of the heating and pressurizing unit include a combination of a heating roller and a pressure roller, and a combination of a heating roller, a pressure roller, and an endless belt.

The fixing section preferably has a heating element having a heat generating element, a film in contact with the heating element, and a pressure member in pressure contact with the heating element via the film, and is a heating and pressure member that can heat and fix the recording medium on which an unfixed image has been formed by passing the recording medium between the film and the pressure member.

The heating temperature in the heating and pressurizing section is usually preferably between 80°C and 200°C.

The surface pressure in the heating and pressing section is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 N/cm ² to 80 N/cm ² .

In this embodiment, depending on the purpose, for example, a known optical fixing device may be used together with or instead of the fixing unit.

[others]
The image forming apparatus according to the embodiment may further include, for example, a static eliminator, a recycle unit, a controller, and the like.

(Static charge removal section)
The charge removing section is not particularly limited as long as it can apply a charge removing bias to the image bearing member, and can be appropriately selected from among known charge removers. For example, a charge removing lamp is preferably used.

(Recycling Department)
The recycling section is not particularly limited, and examples thereof include known conveying means.

(Control Unit)
The control unit can control the movement of each of the above-mentioned parts. The control unit is not particularly limited as long as it can control the movement of each of the above-mentioned parts, and can be appropriately selected depending on the purpose. For example, the control unit can be a control device such as a sequencer or a computer.

As described above, the image forming apparatus according to one embodiment has a cleaning section equipped with a cleaning blade. The cleaning blade has an elastic member that removes toner adhering to the surface of the member to be cleaned. The elastic member has a tip ridge that contacts the member to be cleaned, and contains domains derived from a polysiloxane structure with an average dispersion diameter of 0.1 μm to 5.0 μm in a region from the surface including the tip ridge to a depth of 100 μm. The elastic member has a large amount of polysiloxane near the contact portion including the tip ridge, and the toner contains 20% or more by number of particles with a particle diameter of 3 μm or less, so that the particles contained in the toner can aggregate with the polysiloxane near the contact portion to form a strong deposition layer (dam layer). In addition, since the elastic member has very high sliding properties, the posture of the elastic member can be constantly stable. Therefore, the dam layer formed on the elastic member can be maintained for a long time.

Therefore, by combining the elastic member having the above configuration with a toner containing 20% or more of particles with a particle diameter of 3 μm or less, the cleaning blade can easily aggregate with the polysiloxane near the contact portion of the elastic member, forming a stronger dam layer. Therefore, the cleaning blade according to one embodiment can improve resistance in high temperature (e.g., 40° C. or higher) and high humidity (e.g., 70 RH or higher) environments, and can have excellent cleaning properties even in harsh environments.

Therefore, the image forming apparatus according to one embodiment uses a cleaning blade having the above-mentioned configuration in a cleaning device, and is therefore able to remove toner and other deposits that have formed on the member being cleaned even in harsh operating environments. As a result, the image forming apparatus according to one embodiment has excellent cleaning properties even in harsh environments, and is therefore able to stably provide high-quality images.

In an image forming apparatus according to one embodiment, the cleaning blade can have a Martens hardness HM of the elastic member at a position 20 μm deep from the surface of the edge line of the tip end of the cleaning blade of 0.5 N/mm ² or more and less than 1.5 N/mm ^2. This allows the cleaning blade to have high hardness even in high temperature (e.g., 40° C. or more) and high humidity (e.g., 70 RH or more) environments.

In an image forming apparatus according to one embodiment, the cleaning blade can have an average dispersion diameter of the domains derived from the polysiloxane structure of 0.5 μm to 2.0 μm. This allows the cleaning blade to have increased durability. Therefore, the image forming apparatus according to one embodiment can have higher cleaning performance even in harsh environments.

In the image forming device according to one embodiment, the cleaning blade can have an elastic member with a single layer structure or a multi-layer structure. This allows the cleaning blade to use an elastic member with any rigidity depending on the type of member to be cleaned. Therefore, the image forming device according to one embodiment can reliably exhibit cleaning performance.

In this embodiment, in the image forming apparatus according to one embodiment, the deposits to be removed by the cleaning blade may include, in addition to toner, lubricants, dirt, dust, etc. that adhere to the surface of the member to be cleaned.

<Image forming method>
An image forming method according to an embodiment will be described below. The image forming method according to an embodiment is performed using an image forming apparatus according to an embodiment.

The image forming method according to one embodiment includes an electrostatic latent image forming step of forming an electrostatic latent image on a carrier which is a member to be cleaned, a developing step of developing the electrostatic latent image with toner to form a visible image, a transfer step of transferring the visible image to a recording medium, a fixing step of fixing the transferred image transferred to the recording medium, and a cleaning step of removing the toner remaining on the image carrier with a cleaning blade. In the image forming method according to one embodiment, a cleaning blade having the above-mentioned configuration is used as the cleaning blade. The toner used contains at least 20% by number of particles having a particle diameter of 3 μm or less. The image forming method according to one embodiment may further include other steps as necessary, such as a cleaning auxiliary step of applying a lubricant to the image carrier.

As described above, the image forming method according to one embodiment can be performed by the image forming apparatus according to one embodiment. The electrostatic latent image forming process can be suitably performed by an electrostatic latent image forming unit, the developing process can be suitably performed by a developing unit, the transfer process can be suitably performed by a transfer unit, the fixing process can be suitably performed by a fixing unit, the cleaning process can be suitably performed by a cleaning unit, and other processes can be suitably performed by other units.

The electrostatic latent image forming process is a process of forming an electrostatic latent image on an image carrier, and includes a charging process of charging the surface of the image carrier, and an exposure process of exposing the charged surface of the image carrier to light to form an electrostatic latent image. Charging can be performed, for example, by applying a voltage to the surface of the image carrier using a charger. Exposure can be performed, for example, by exposing the surface of the image carrier in an imagewise manner using the exposure device. The formation of an electrostatic latent image can be performed, for example, by uniformly charging the surface of the image carrier and then exposing it in an imagewise manner, and can be performed by an electrostatic latent image forming unit.

The developing process is a process in which the electrostatic latent image is developed sequentially with toners of multiple colors to form a toner image. The toner image can be formed, for example, by developing the electrostatic latent image with the toner, and can be performed using a developing device.

In the developing unit, for example, toner and carrier are mixed and stirred, and the toner becomes charged due to friction during this process and is held in a raised state on the surface of the rotating magnet roller, forming a magnetic brush. Since the magnet roller is placed near the image carrier (photoconductor), some of the toner that makes up the magnetic brush formed on the surface of the magnet roller moves to the surface of the image carrier (photoconductor) by electrical attraction. As a result, the electrostatic latent image is developed with toner, and a toner image made of toner is formed on the surface of the image carrier (photoconductor).

The transfer process is a process of transferring a toner image to a recording medium. The transfer process preferably uses an intermediate transfer body, and after the toner image is primarily transferred onto the intermediate transfer body, the toner image is secondarily transferred onto the recording medium. The transfer process more preferably includes a primary transfer process using two or more color toners, preferably full-color toners, in which the toner image is transferred onto the intermediate transfer body to form a composite transfer image, and a secondary transfer process in which the composite transfer image is transferred onto the recording medium. The transfer can be performed, for example, by charging the image carrier (photoconductor) with the toner image using a transfer charger, and can be performed by the transfer section.

The fixing process is a process in which the toner image transferred to the recording medium is fixed using a fixing device. This process may be performed for each color of developer each time it is transferred to the recording medium, or it may be performed simultaneously for each color of developer in a stacked state.

The cleaning process is a process for removing toner remaining on the image carrier, and can be suitably performed by the cleaning unit.

The image forming method according to one embodiment may further include other processes appropriately selected as necessary, such as a static electricity removal process, a cleaning process, etc.

The static elimination process is a process in which a static elimination bias is applied to the image carrier to eliminate static electricity, and can be suitably performed by the static elimination unit.

The recycling process is a process in which the toner removed in the cleaning process is recycled to the development section, and can be suitably carried out by the recycling section.

The image forming method according to one embodiment uses the image forming apparatus according to one embodiment, and by using the cleaning blade and toner having the above-mentioned configuration, it is possible to form an image while removing the toner remaining on the image carrier. Therefore, according to the image forming method according to one embodiment, it is possible to provide high-quality images stably because it has excellent cleaning properties even in harsh environments.

[One aspect of the image forming apparatus]
Next, one aspect of an image forming apparatus according to an embodiment will be described with reference to Fig. 7. Fig. 7 is a schematic diagram showing an example of an image forming apparatus according to an embodiment. Note that, although electrophotographic image forming apparatuses include printers, copiers, facsimiles, etc., Fig. 7 describes a case where the image forming apparatus is a printer.

As shown in FIG. 7, an electrophotographic image forming apparatus (printer) 100 includes four imaging units 10Y, 10C, 10M, and 10K for yellow, magenta, cyan, and black (hereinafter referred to as Y, C, M, and K, respectively), a transfer unit 20 which is a transfer section, an optical writing unit 30 which is a latent image forming section, a paper feed unit 40, a pair of registration rollers 50, a fixing unit 60 which is a fixing section, toner cartridges 70Y, 70C, 70M, and 70K, and a secondary transfer roller 80. These use different colors of Y, C, M, and K toner as image forming substances to form images, but are otherwise similar in configuration.

Imaging units 10Y, 10C, 10M, and 10K are equipped with drum-shaped photoreceptors 11Y, 11C, 11M, and 11K.

Figure 8 is a schematic diagram showing the configuration of the four imaging units 10Y, 10C, 10M, and 10K. Since the imaging units 10Y, 10C, 10M, and 10K are similar except for the type of toner they use, in Figure 8, the configuration of the imaging unit 10Y is described, and the configurations of the other imaging units 10C, 10M, and 10K are omitted. As shown in Figure 8, the imaging unit 10Y includes a photoconductor 11Y, a charging device 12Y, a developing device 13Y, a cleaning device 15Y, a lubricant application device 16Y, a cleaning roller 17Y, a static electricity removal lamp, etc., within a frame 18. The charging device 12Y, the developing device 13Y, the cleaning device 15Y, the lubricant application device 16Y, the static electricity removal lamp, etc. are arranged around the photoconductor 11Y.

Although the photoreceptor 11Y is shown to have a drum shape, it may also be in the form of a sheet or an endless belt.

The charging device 12Y may be a known device such as a corotron, scorotron, or solid-state charger. Of these charging methods, the contact charging method and the non-contact close-by arrangement method are particularly preferable, as they have the advantages of increasing charging efficiency, reducing the amount of ozone generated, and enabling the device to be made more compact.

In this embodiment, the charging device 12Y includes a charging roller 121Y, which is a charging member. The charging device 12Y uses a non-contact close-by arrangement method in which the charging roller 121Y is placed close to the photoconductor 11Y.

The charging roller 121Y is disposed at a predetermined distance from the photoconductor 11Y without contacting it, and charges the photoconductor 11Y to a predetermined polarity and a predetermined potential. The surface of the photoconductor 11Y that has been uniformly charged by the charging roller 121Y is irradiated with laser light L from the optical writing unit 30, which is a latent image forming means, based on image information, and an electrostatic latent image is formed.

The developing device 13Y converts the latent image formed on the surface of the photoconductor 11Y into a toner image. The developing device 13Y has a developing roller 131Y as a developer carrier, a supply screw 132Y, an agitating screw 133Y, and a doctor 134Y.

A developing bias is applied to the developing roller 131Y from a power source.

The supply screw 132Y and the stirring screw 133Y are provided inside the casing of the developing device 13Y and stir the developer contained in the casing while transporting it in opposite directions.

The doctor 134Y regulates the developer carried by the developing roller 131Y.

In the developing device 13Y, the toner in the developer that is stirred and transported by the twin screws of the supply screw 132Y and the stirring screw 133Y is charged to a predetermined polarity. The developer is then pumped up onto the surface of the developing roller 131Y, where it is regulated by the doctor 134Y, and the toner adheres to the latent image on the photoreceptor 11Y in the development area facing the photoreceptor 11Y.

The cleaning device 15Y cleans the toner remaining on the photoconductor 11Y after the toner image is transferred to the intermediate transfer belt 21 of the transfer unit 20. The cleaning device 15Y has a fur brush 151Y, a cleaning blade 152Y, etc.

The fur brush 151Y rotates in the same direction as the photoreceptor 11Y, scraping off the solid lubricant 161 provided on the lubricant applicator 16Y and applying the solid lubricant 161 onto the photoreceptor 11Y.

The cleaning blade 152Y contacts the photoreceptor 11Y in a counter direction to the surface movement direction of the photoreceptor 11Y. The cleaning blade 152Y is the cleaning blade provided in the image forming apparatus according to the embodiment described above.

The lubricant applicator 16Y is a lubricant applicator that applies lubricant to the surface of the photoconductor 11Y after cleaning by the cleaning device 15Y. The lubricant applicator 16Y includes a solid lubricant 161, a bracket 162, a lubricant pressure spring 163, etc.

The solid lubricant 161 is applied onto the photoreceptor 11Y using the fur brush 151Y. The bracket 162 holds the solid lubricant 161. The lubricant pressure spring 163 presses the solid lubricant 161 held by the bracket 162 toward the fur brush 151Y.

In the lubricant application device 16Y, the solid lubricant 161 is scraped off by the fur brush 151Y, and the solid lubricant 161 is applied onto the photoreceptor 11Y. By applying the solid lubricant 161 to the photoreceptor 11Y, it is preferable that the static friction coefficient of the surface of the photoreceptor 11Y be maintained at 0.2 or less when no image is being formed.

The cleaning roller 17Y cleans the charging roller 121Y.

The discharge lamp (not shown) discharges the surface potential of the photoconductor 11Y after cleaning.

As shown in FIG. 7, the transfer unit 20 is disposed above the four image-forming units 1Y, 1C, 1M, and 1K. The transfer unit 20 includes an intermediate transfer belt 21, which is an intermediate transfer body, a belt cleaning unit 22, a first bracket 23, a second bracket 24, primary transfer rollers 25Y, 25C, 25M, and 25K, a secondary transfer backup roller 26, a drive roller 27, an auxiliary roller 28, a tension roller 29, and the like. The transfer unit 20 transfers the toner images of each color formed on the surfaces of the photoconductors 11Y, 11C, 11M, and 11K onto the surface of the intermediate transfer belt 21 in a superimposed manner.

The intermediate transfer belt 21 is an endless belt stretched over eight rollers arranged on the inside, and is designed to be able to move endlessly in the direction of the arrow by the rotational drive of the drive roller 27.

The first bracket 23 houses the primary transfer rollers 25Y, 25C, and 25M inside, and swings at a predetermined rotation angle around the axis of rotation of the auxiliary roller 28 as the solenoid is turned on and off.

The second bracket 24 houses the primary transfer roller 25K inside.

The primary transfer rollers 25Y, 25C, 25M and 25K are primary transfer members provided in the primary transfer device as a primary transfer means for transferring the toner images on the surfaces of the photoreceptors 11Y, 11C, 11M and 11K to the intermediate transfer belt 21. The primary transfer rollers 25Y, 25C, 25M and 25K sandwich the intermediate transfer belt 21 between the photoreceptors 11Y, 11C, 11M and 11K to form primary transfer nips. The primary transfer rollers 25Y, 25C, 25M and 25K apply a transfer bias of the opposite polarity (e.g., positive) to the toner to the back surface (loop inner surface) of the intermediate transfer belt 21. As the intermediate transfer belt 21 moves endlessly, the Y, C, M and K toner images on the photoreceptors 11Y, 11C, 11M and 11K are superimposed on the surface of the intermediate transfer belt 21 in the process of passing through the primary transfer nips for Y, C, M and K in sequence. As a result, a four-color superimposed toner image (hereafter referred to as a four-color toner image) is formed on the intermediate transfer belt 21.

The secondary transfer backup roller 26 sandwiches the intermediate transfer belt 21 between itself and the secondary transfer roller 80, which is disposed outside the loop of the intermediate transfer belt 21, forming a secondary transfer nip.

The drive roller 27 is a roller that drives the intermediate transfer belt 21 to rotate.

The auxiliary roller 28 and tension roller 29 are arranged inside the intermediate transfer belt 21 and are rollers for moving the intermediate transfer belt 21 endlessly.

The optical writing unit 30 is disposed below the four imaging units 10Y, 10C, 10M, and 10K. The optical writing unit 30 irradiates the photoconductors 11Y, 11C, 11M, and 11K with laser light L emitted based on image information. This forms electrostatic latent images for Y, C, M, and K on the photoconductors 11Y, 11C, 11M, and 11K.

The optical writing unit 30 includes a polygon mirror 31 that is rotated by a motor to irradiate the laser light L emitted from the light source. The optical writing unit 30 deflects the laser light L using the polygon mirror 31 and irradiates the laser light L onto the photoconductors 11Y, 11C, 11M, and 11K via multiple optical lenses and mirrors. Instead of this configuration, the optical writing unit 30 may include one that performs optical scanning using an LED array.

Light sources for the laser light L of the optical writing unit 30 and for the discharge lamp can be any light-emitting device, such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light-emitting diode (LED), a semiconductor laser (LD), or an electroluminescence (EL).

In addition, various filters such as sharp cut filters, band pass filters, near infrared cut filters, dichroic filters, interference filters, and color temperature conversion filters can be used to irradiate only light in the desired wavelength range.

Of these light sources, light-emitting diodes and semiconductor lasers are well suited because they have high irradiation energy and emit light with long wavelengths of 600 to 800 nm.

The paper feed unit 40 has a first paper feed cassette 41A and a second paper feed cassette 41B, a first paper feed roller 42A and a second paper feed roller 42B, a paper feed path 43, and multiple pairs of conveying rollers 44.

The first and second paper feed cassettes 41A and 41B are arranged below the optical writing unit 30 so that the first and second paper feed cassettes 41A and 41B are stacked vertically. Each of these paper feed cassettes contains a stack of transfer paper P, which is a recording medium.

The first feed roller 42A and the second feed roller 42B are positioned to contact the topmost transfer paper P in the first feed cassette 41A and the second feed cassette 41B, respectively.

The paper feed path 43 is the path through which the transfer paper P in the first paper feed cassette 41A and the second paper feed cassette 41B is discharged.

The multiple transport roller pairs 44 are each arranged to sandwich the transfer paper P through the paper feed path 43, and transport the transfer paper P from the bottom to the top in FIG. 7.

In the paper feed unit 40, when the first paper feed roller 42A is driven to rotate counterclockwise by the drive means, the top transfer paper P in the first paper feed cassette 41A is discharged toward the paper feed path 43 that is arranged to extend vertically to the right side of the first paper feed cassette 41A in FIG. 7. When the second paper feed roller 42B is driven to rotate counterclockwise by the drive means in FIG. 7, the top transfer paper P in the second paper feed cassette 41B is discharged toward the paper feed path 43.

A number of pairs of transport rollers 44 are arranged in the paper feed path 43. The transfer paper P fed into the paper feed path 43 is sandwiched between the rollers of these transport roller pairs 44 and transported within the paper feed path 43 from the bottom to the top in FIG. 7.

The registration roller pair 50 is disposed at the downstream end of the paper feed path 43 in the transport direction. As soon as the registration roller pair 50 sandwiches the transfer paper P fed from the transport roller pair 44 between the rollers, it temporarily stops the rotation of both rollers. The registration roller pair 50 then sends the transfer paper P sandwiched between the rollers toward the secondary transfer nip at a timing that allows it to be synchronized with the four-color toner image on the intermediate transfer belt 21.

The fixing unit 60 is disposed above the secondary transfer nip in the figure. The fixing unit 60 includes a pressure heating roller 61 and a fixing belt unit 62 that includes a heat source such as a halogen lamp.

The fixing belt unit 62 includes a fixing belt 621, which is a fixing member, a heating roller 622 containing a heat source such as a halogen lamp, a tension roller 623, a drive roller 624, a temperature sensor, etc. In the fixing belt unit 62, the endless fixing belt 621 is stretched by the heating roller 622, the tension roller 623, and the drive roller 624, and moves endlessly in the counterclockwise direction in the figure. During this endless movement, the fixing belt 621 is heated from the back side by the heating roller 622. The pressure heating roller 61, which is driven to rotate in the clockwise direction in the figure, abuts on the surface side of the fixing belt 621, which is heated in this way, at the point where it is wrapped around the heating roller 622. This forms a fixing nip where the pressure heating roller 61 and the fixing belt 621 abut.

A temperature sensor is disposed on the outside of the loop of the fixing belt 621 so as to face the surface of the fixing belt 621 with a specified gap therebetween, and detects the surface temperature of the fixing belt 621 immediately before it enters the fixing nip. The detection result is sent to a fixing power supply circuit (not shown). Based on the detection result by the temperature sensor, the fixing power supply circuit turns on and off the power supply to the heat source contained in the heating roller 622 and the heat source contained in the pressure heating roller 61.

After passing through the secondary transfer nip described above, the transfer paper P is separated from the intermediate transfer belt 21 and then sent into the fixing unit 60. Then, in the process of being conveyed from the bottom to the top in the figure while being sandwiched in the fixing nip inside the fixing unit 60, the full-color toner image is fixed to the transfer paper P by being heated and pressed by the fixing belt 621.

The transfer paper P that has been subjected to the fixing process in this manner passes between the rollers of the discharge roller pair 91 and is then discharged outside the machine. A stack section 92 is formed on the top surface of the housing of the printer 100 main body, and the transfer paper P discharged outside the machine by the discharge roller pair 91 is stacked in this stack section 92 in sequence.

Toner cartridges 70Y, 70C, 70M, and 70K are provided above transfer unit 20 and contain Y, C, M, and K toner, respectively. The Y, C, M, and K toner in toner cartridges 70Y, 70C, 70M, and 70K are supplied appropriately to the developing devices of imaging units 10Y, 10C, 10M, and 10K. These toner cartridges 70Y, 70C, 70M, and 70K are detachable from the printer body independently of imaging units 10Y, 10C, 10M, and 10K.

A secondary transfer bias is applied to the secondary transfer roller 80. The secondary transfer roller 80 is a secondary transfer member that performs secondary transfer of the four-color toner image on the intermediate transfer belt 21 to the transfer paper P in one go. The four-color toner image on the intermediate transfer belt 21 is secondary transferred in one go to the transfer paper P in the secondary transfer nip due to the influence of the secondary transfer electric field and nip pressure formed between the secondary transfer roller 80 and the secondary transfer backup roller 26. Then, combined with the white color of the transfer paper P, it becomes a full-color toner image.

After passing through the secondary transfer nip, residual toner that has not been transferred to the transfer paper P adheres to the intermediate transfer belt 21. The residual toner is cleaned by the belt cleaning unit 22. The belt cleaning unit 22 includes a belt cleaning blade 221. The belt cleaning blade 221 is brought into contact with the surface of the intermediate transfer belt 21 to scrape off and remove the residual toner on the intermediate transfer belt 21. The belt cleaning blade 221 can be a cleaning blade according to one embodiment.

When forming a monochrome image, the printer 100 rotates the first bracket 23 slightly counterclockwise in the figure by driving the solenoid described above. This rotation causes the primary transfer rollers 25Y, 25C, and 25M for Y, C, and M to revolve counterclockwise in the figure around the rotation axis of the auxiliary roller 28, and the intermediate transfer belt 21 is separated from the photoconductors 11Y, 11C, and 11M for Y, C, and M. Then, of the four imaging units 10Y, 10C, 10M, and 10K, only the imaging unit 10K for K is driven to form a monochrome image. This makes it possible to avoid wear and tear on the components that make up the imaging units due to unnecessary driving of the imaging units for Y, C, and M when forming a monochrome image.

Next, we will explain the image formation operation of the printer 100.

When a print execution signal is received from an operation unit or the like, a predetermined voltage or current is applied sequentially and at a predetermined timing to the charging rollers 121Y, 121C, 121M, and 121K and the developing rollers 131Y, 131C, 131M, and 131K. Similarly, a predetermined voltage or current is applied sequentially and at a predetermined timing to the optical writing unit 30 and light sources such as the static electricity removal lamp. Synchronously with this, the photoconductors 11Y, 11C, 11M, and 11K are rotated in the direction of the arrow in the figure by a photoconductor drive motor (not shown), which serves as a drive means.

When photoconductors 11Y, 11C, 11M, and 11K rotate in the direction of the arrow in the figure, the surfaces of photoconductors 11Y, 11C, 11M, and 11K are first uniformly charged to a predetermined potential by charging rollers 121Y, 121C, 121M, and 121K. Then, laser light L corresponding to image information is irradiated onto photoconductors 11Y, 11C, 11M, and 11K from optical writing unit 30, and the portions of the surfaces of photoconductors 11Y, 11C, 11M, and 11K irradiated with laser light L are discharged, forming an electrostatic latent image.

The surfaces of the photoconductors 11Y, 11C, 11M and 11K on which the electrostatic latent images are formed are rubbed by a magnetic brush of developer formed on the developing roller 131Y at the portion facing the developing devices 13Y, 13C, 13M and 13K. At this time, the negatively charged toner on the developing rollers 131Y, 131C, 131M and 131K moves to the electrostatic latent image side by a predetermined developing bias applied to the developing rollers 131Y, 131C, 131M and 131K, and is turned into a toner image (developed). In each of the imaging units 10Y, 10C, 10M and 10K, a similar imaging process is performed, and a toner image of each color is formed on the surface of each of the photoconductors 11Y, 11C, 11M and 11K of each of the imaging units 10Y, 10C, 10M and 10K.

In this way, in printer 100, the electrostatic latent images formed on photoconductors 11Y, 11C, 11M, and 11K are reverse-developed by developing devices 13Y, 13C, 13M, and 13K with negatively charged toner. Note that, in this embodiment, an example using an N/P (negative/positive: toner adheres to areas with low potential) non-contact charging roller method has been described, but the present invention is not limited to this.

The toner images of each color formed on the surface of each photoconductor 11Y, 11C, 11M, and 11K are sequentially transferred in a primary manner so as to be superimposed on the surface of the intermediate transfer belt 21. As a result, a four-color toner image is formed on the intermediate transfer belt 21.

The four-color toner image formed on the intermediate transfer belt 21 is transferred onto the transfer paper P, which is fed from the first paper feed cassette 41A or the second paper feed cassette 41B and passes between the rollers of the registration roller pair 50 and is fed to the secondary transfer nip. At this time, the transfer paper P stops once while being sandwiched between the registration roller pair 50, and is fed to the secondary transfer nip in synchronization with the leading edge of the image on the intermediate transfer belt 21. The transfer paper P with the toner image transferred thereto is separated from the intermediate transfer belt 21 and transported to the fixing unit 60. Then, as the transfer paper P with the toner image transferred thereto passes through the fixing unit 60, the toner image is fixed onto the transfer paper P by the action of heat and pressure, and the transfer paper P with the fixed toner image is discharged outside the printer 100 device and stacked in the stack section 92.

Meanwhile, the surface of the intermediate transfer belt 21, from which the toner image has been transferred to the transfer paper P in the secondary transfer nip, has any residual toner remaining on the surface removed by the belt cleaning unit 22.

The surfaces of the photoconductors 11Y, 11C, 11M and 11K, which have transferred the toner images of each color to the intermediate transfer belt 21 at the primary transfer nip, have residual toner removed by cleaning devices 15Y, 15C, 15M and 15K, have lubricant applied by lubricant application device 16Y and are then discharged by a discharge lamp.

The imaging units 10Y, 10C, 10M, and 10K of the printer 100 are detachable from the printer 100 body as a process cartridge. In the printer 100, the imaging units 10Y, 10C, 10M, and 10K are configured so that the photoconductors 11Y, 11C, 11M, and 11K and the process means as process cartridges are replaced as a whole. Note that the imaging units 10Y, 10C, 10M, and 10K may be replaced by replacing the individual members constituting the imaging units 10Y, 10C, 10M, and 10K, such as the photoconductors 11Y, 11C, 11M, and 11K.

The following examples and comparative examples are used to further explain the embodiments, but the embodiments are not limited to these examples and comparative examples.

<Preparation of cleaning blade>
[Molding of substrate]
The substrate constituting the elastic member was prepared by centrifugal molding of a polyurethane elastomer sheet having the following film thickness, JIS-A hardness, resilience modulus, and Martens hardness (HM).
Film thickness: 1.5 mm
・JIS-A hardness: 70°
・Rebound elasticity: 50%
・ Martens hardness (HM): 1.0 N/ ^mm2

The methods for measuring the film thickness, JIS-A hardness, resilience modulus, and Martens hardness (HM) of the substrate are shown below.

(Film Thickness)
The substrate was cut, and the thickness of the cut surface was measured using a microscope to determine the film thickness of the substrate.

(JIS-A hardness of substrate)
The JIS-A hardness of the substrate was measured at 23° C.±2° C. using a micro rubber hardness tester MD-1 manufactured by Kobunshi Keiki Co., Ltd. in accordance with JIS K6253.

(Rebound elasticity)
The resilience modulus of the substrate was measured in accordance with JIS K6255 using a resilience tester No. 221 manufactured by Toyo Seiki Seisakusho at 23° C. The sample used was a sheet having a thickness of 4 mm or more, in which two sheets having a thickness of 2 mm were stacked together.

(Martens hardness)
The Martens hardness (HM) of the substrate was measured according to ISO 14577 using an Elionix Nano Indenter ENT-3100 by pressing a Berkovich indenter with a load of 1000 μN for 10 seconds, holding it for 5 seconds, and removing it at the same load rate for 10 seconds. The measurement was performed at a position 20 μm from the tip ridge of the bladed sheet after molding. The Martens hardness (HM) of the substrate was 1.0 N/ ^mm2 .

<Formation of Elastic Member>
The materials used in the composition for forming an elastic member for forming the base material, which is an elastic member, are shown below.

- Isocyanate -
4,4'-Diphenylmethane diisocyanate (MDI): "Millionate MT", manufactured by Tosoh Corporation;
HMDI (dicyclohexylmethane 4,4'-diisocyanate (hydrogenated MDI)): manufactured by Tokyo Chemical Industry Co., Ltd. 2,4-tolylene diisocyanate (TDI): "Coronate T-100", manufactured by Tosoh Corporation

-Polyol-
Polytetramethylene ether glycol (PTMG): "PTMG1000" manufactured by Mitsubishi Chemical Corporation Polycaprolactone diol (PCL): "Placcel 205" manufactured by Daicel Corporation

- Hardener -
DETDA (Ethacure 100): manufactured by Mitsui Fine Chemicals, Inc. 1,4-butanediol (BD): manufactured by Mitsubishi Chemical Corporation Trimethylolpropane (TMP): manufactured by Mitsubishi Gas Chemical Company, Inc.

-Siloxane compounds-
・One-terminated carbinol-modified silicone oil: X-22-176DX, manufactured by Shin-Etsu Silicone Co., Ltd. ・Dimethyl silicone oil: KF96-3000cs, manufactured by Shin-Etsu Silicone Co., Ltd.

-Synthesis of NCO-Terminated Silicone Prepolymer (Prepolymer A1)-
As shown in Table 1 below, 4,4'-diphenylmethane diisocyanate (MDI, manufactured by Tosoh Corporation) and one-terminated carbinol-modified silicone oil (X-22-176DX, manufactured by Shin-Etsu Chemical Co., Ltd.) were reacted at 60°C for 90 minutes to obtain an NCO-terminated silicone prepolymer (Prepolymer A1) having an isocyanate (NCO) content of 3.2%.

-Synthesis of NCO-Terminated Urethane Prepolymer (Prepolymer B)-
As shown in Table 2 below, isocyanate and polyol were mixed so as to obtain the desired NCO % and reacted with 0.01 g of tin catalyst dibutyltin dilaurate at 80° C. for 90 minutes to prepare NCO-terminated urethane prepolymers B1 and B2.

- Preparation of hardener -
Curing agents 1 and 2 were prepared as shown in Table 3 below.

[Preparation of cleaning blade 1]
Prepolymers A1 and B2 and silicone oil (KF96, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed in the formulation shown in Table 4 and stirred with a homogenizer (15,000 rpm) to obtain a first composition.

After adding the curing agent 2 to the first composition in which the silicone oil was emulsified and heated to 80°C, the mixture was poured into a centrifugal drum heated to 165°C and reacted for 30 minutes to obtain a rubber sheet, which is an elastic member, having a thickness of 1.8 mm. The first composition and the curing agent 2 were mixed so that the R value (NCO group/OH group molar ratio) was 0.925.

This rubber sheet was cut into a rectangular shape so that it could be mounted on a color multifunction printer (imagio MP C4500, manufactured by Ricoh Co., Ltd.) to obtain an elastic member. The elastic member was fixed to a metal holder (support member) with adhesive. In this way, cleaning blade 1 was obtained.

[Average dispersion diameter of domains derived from polysiloxane structure]
The obtained elastic member was sliced in a plane perpendicular to the longitudinal direction, and with the cross section facing upward, a 100 μm region including the tip ridge was observed with a laser microscope (OLS4100, manufactured by Olympus Corporation).

The elastic member was sliced into rings using a vertical slicer and a razor to cut the elastic member perpendicular to its longitudinal direction so that the thickness of the elastic member in the longitudinal direction was 3 mm.

The dispersion diameter of the domains was measured for the observed images using ImagePro ver. 5.1. The length of a line segment connecting two points on the periphery of the domain observed in the cross section and passing through the center of gravity of the domain was measured in increments of 2 degrees. The average length of the measured line segment was taken as the dispersion diameter of the domain. The dispersion diameters of 100 to 200 domains were measured, and the number-average value was calculated, which was taken as the average dispersion diameter.

[Domain area ratio]
The elastic member was cut at the relevant location to expose the cross section, and a 100 μm region including the tip ridge was photographed using a laser microscope (OLS4100, manufactured by Olympus Corporation). The obtained image was binarized using ImagePro, and the area ratio (unit: %) occupied by the siloxane-based compound was calculated to determine the area ratio of the domain in the cross section of the 100 μm region including the tip ridge.

[Average thickness of elastic member]
The tip surface of the cleaning blade 1 was faced upward, and 10 points were observed with a digital microscope (VHX-2000, manufactured by Keyence Corporation), and the arithmetic mean value was taken as the average thickness.

[Martens hardness of cleaning blade]
The Martens hardness of the cleaning blade 1 was measured in the same manner as the Martens hardness of the above-mentioned substrate.

[Preparation of Cleaning Blades 2 to 6]
Cleaning blades 2 to 6 were produced in the same manner as cleaning blade 1, except that the types of the first composition and curing agent, the homogenizer time, and the curing temperature in cleaning blade 1 were changed as shown in Table 4. The first composition and curing agent 1 or 2 were mixed so that the R value (NCO group/OH group molar ratio) was 0.925.

The composition, rubber sheet thickness, and manufacturing conditions of cleaning blades 1 to 6 are shown in Table 4.

Example 1
[Toner Preparation]
(Preparation of first binder resin)
600 g of styrene, 110 g of butyl acrylate, and 30 g of acrylic acid as vinyl monomers, and 30 g of dicumyl peroxide as a polymerization initiator were placed in a dropping funnel. 1230 g of polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, 290 g of polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane as polyols, 250 g of isododecenyl succinic anhydride, 310 g of terephthalic acid, 180 g of 1,2,4-benzenetricarboxylic anhydride, and 7 g of dibutyltin oxide as an esterification catalyst were placed in a 5-liter four-neck flask equipped with a thermometer, a stainless steel stirrer, a downflow condenser, and a nitrogen inlet tube. The four-necked flask was placed in a mantle heater, and the mixture in the four-necked flask was stirred at 160° C. under a nitrogen atmosphere, while the mixture of the vinyl monomer and the polymerization initiator was dropped from the dropping funnel into the mixture in the four-necked flask over one hour. After the addition polymerization reaction was allowed to mature for two hours while maintaining the temperature at 160° C., the mixture in the four-necked flask was heated to 230° C. to carry out a condensation polymerization reaction. The degree of polymerization was tracked by the softening point measured using a constant load extrusion capillary rheometer, and the reaction was terminated when the desired softening point was reached. This resulted in the production of a first binder resin.

(Preparation of second binder resin)
2210 g of polyoxypropylene (2.2)-2,2-bis (4-hydroxyphenyl) propane as polyol, 850 g of terephthalic acid, 120 g of 1,2,4-benzenetricarboxylic anhydride, and 0.5 g of dibutyltin oxide as esterification catalyst were placed in a 5-liter four-neck flask equipped with a thermometer, a stainless steel stirrer, a downflow condenser, and a nitrogen inlet tube. The four-neck flask was placed in a mantle heater, and the mixture in the four-neck flask was heated to 230°C under a nitrogen atmosphere to carry out a condensation polymerization reaction. The degree of polymerization was tracked by the softening point measured using a constant-load extrusion capillary rheometer, and the reaction was terminated when the desired softening point was reached. In this way, a second binder resin was obtained.

100 parts by mass of binder resin containing the first binder resin and the second binder resin were thoroughly mixed with a master batch containing 4 parts by mass of C.I. Pigment Red 57-1, a desired amount of paraffin wax, and a boron-based charge control agent in a Henschel mixer. The mixture was then melt-kneaded using a twin-screw extrusion kneader (PCM-30: manufactured by Ikegai Iron Works). The resulting kneaded material was rolled to a thickness of 2 mm with a cooling press roller, cooled with a cooling belt, and then coarsely crushed with a feather mill. The mixture was then crushed to a volume average particle size of 10 μm to 12 μm with a mechanical crusher (KTM: manufactured by Kawasaki Heavy Industries, Ltd.), and further crushed with a jet crusher (IDS: manufactured by Nippon Pneumatic Industry Co., Ltd.) to obtain colored resin particles with a volume average particle size of 3 μm or less at 22% by number. 100 parts by mass of these colored resin particles were mixed with 0.8 parts by mass of H20TM (primary particle diameter 12 nm, manufactured by Clariant) using a Henschel mixer at a peripheral speed of 40 m/s for 5 minutes. This resulted in a toner.

[Proportion of toner particles with a particle diameter of 3 μm or less]
First, the particle size of the toner was determined. The particle size of the toner was measured using a Coulter Multisizer III (manufactured by Coulter, Inc.). The measurement of the toner particle size was performed as follows.

First, 2 mL of a surfactant (sodium dodecylbenzenesulfonate, manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a dispersant to 100 mL of the electrolyte. The electrolyte was prepared by using first-class sodium chloride to prepare an approximately 1% NaCl aqueous solution, and ISOTON-II (manufactured by Coulter Corporation) was used. 10 mg of the measurement sample was added as solids to the mixture of the electrolyte and the surfactant to obtain an electrolytic volume in which the sample was suspended. The electrolyte in which the sample was suspended was dispersed using an ultrasonic disperser for approximately 1 to 3 minutes, and the toner volume and number were measured using a Coulter Multisizer III with a 100 μm aperture as the aperture, and the volume distribution and number distribution were calculated. From the distribution obtained, the volume average particle diameter (Dv) and number average particle diameter (Dp) of the toner were obtained.

Next, the percentage of particles in the toner with a particle diameter of 3 μm or less was determined. In this example, particles with a particle diameter of 2.00 μm or more and less than 40.30 μm were targeted. "Percentage of particles with a particle diameter of 3 μm or less" refers to the percentage of particles with a particle diameter of less than 3.17 μm (number %), which is the ratio of the number of particles with a particle diameter of less than 3.17 μm to the number of particles with a particle diameter of 2.00 μm or more and less than 40.30 μm.

As channels for sorting particles, for example, 13 channels were used: 2.00 μm or more and less than 2.52 μm; 2.52 μm or more and less than 3.17 μm; 3.17 μm or more and less than 4.00 μm; 4.00 μm or more and less than 5.04 μm; 5.04 μm or more and less than 6.35 μm; 6.35 μm or more and less than 8.00 μm; 8.00 μm or more and less than 10.08 μm; 10.08 μm or more and less than 12.70 μm; 12.70 μm or more and less than 16.00 μm; 16.00 μm or more and less than 20.20 μm; 20.20 μm or more and less than 25.40 μm; 25.40 μm or more and less than 32.00 μm; and 32.00 μm or more and less than 40.30 μm.

<Preparation of Image Forming Apparatus>
The prepared cleaning blade 1 was attached to a process cartridge of a color multifunction printer (imagio MP C4500, manufactured by Ricoh Co., Ltd.) to assemble an image forming apparatus. The cleaning blade 1 was attached to the color multifunction printer so as to have a linear pressure of 20 g/cm and a cleaning angle of 78°.

<Evaluation>
The image forming apparatus was evaluated for cleaning performance and toner scattering.

[Cleaning ability]
Using the above image forming apparatus, 1000 sheets (A4 size landscape) were outputted with 3 prints/job of a chart with an image area ratio of 5% at 23° C./50% RH. This image forming apparatus was stored at 40° C. and 70% for 30 days.

(Evaluation item 1)
Using the image forming apparatus stored as described above, a vertical band image was output under conditions of 27° C. and 80% RH. The output image and the surface of the photoconductor were observed visually and with a laser microscope, and evaluated according to the following evaluation criteria. "◎" and "◯" were acceptable, and "×" was unacceptable.
((Evaluation criteria))
⊚: Toner that has slipped through due to poor cleaning cannot be visually confirmed on either the printed paper or the photoconductor, and no streaks of toner can be confirmed even when observing the photoconductor in the longitudinal direction with a microscope.
◯: Toner that has slipped through due to poor cleaning cannot be visually confirmed on the printed paper or on the photoconductor.
x: Toner that has slipped through due to poor cleaning can be visually confirmed on the printed paper and on the photoconductor.

(Evaluation item 2)
Using the image forming apparatus stored as described above, a full solid image was printed under conditions of 27° C. and 80% RH. The printed image was visually observed and evaluated according to the following evaluation criteria. "◎", "◯" and "△" were acceptable, and "×" was unacceptable.
((Evaluation criteria))
.circleincircle.: No horizontal streaks are visible from the first sheet.
A: White horizontal streaks occurred in the image, but disappeared by the fifth sheet.
△: White horizontal lines occurred in the images, but disappeared on the 6th to 10th sheets.
×: White horizontal lines occurred on the image and did not disappear within the first 10 sheets.

[Toner scattering]
Using the image forming apparatus, 50,000 sheets (A4 size landscape) of a chart with an image area ratio of 15% was output at 20 prints/job under the conditions of 27° C./80% RH. After that, 10 blank sheets were output, and the image and the contamination state of the process cartridge were confirmed.
⊚: No toner scattering was observed on the image or in the process cartridge.
◯: There is no toner scattering in the image, but traces of toner scattering can be seen on the process cartridge.
x: Toner scattering is observed in the image.

<Examples 2 to 5>
The same procedure as in Example 1 was carried out except that, as shown in Table 5, the conditions in the toner pulverization step were changed to change the percentage by number of particles of 3 μm or less in the toner.

<Examples 6 to 10, Comparative Examples 1 to 3>
The same procedure as in Example 1 was repeated except that, as shown in Table 5, cleaning blade 1 was changed to cleaning blades 2 to 8, and the conditions in the toner pulverization process were changed to change the percentage of toner particles having sizes of 3 μm or less.

Table 5 shows the type of cleaning blade used in each example and comparative example, the average dispersion diameter and Martens hardness of the polysiloxane domains, the percentage of toner particles 3 μm or less, and the evaluation results.

From Table 5, it was confirmed that the image forming devices of Examples 1 to 8 met the conditions for use in terms of both cleaning performance and toner scattering. In contrast, it was confirmed that the image forming devices of Comparative Examples 1 to 3 did not meet the conditions for use in terms of cleaning performance, and thus had practical problems.

Therefore, the image forming apparatuses of Examples 1 to 8 are different from the image forming apparatuses of Comparative Examples 1 to 3 in that the cleaning blade contains domains derived from a polysiloxane structure with an average dispersion diameter of 0. μm to 5.0 μm in a region of the elastic member from the surface including the tip ridge to a depth of 100 μm. The toner has a ratio of particles of 3 μm or less to 20% by number or more. This allows the image forming apparatuses of Examples 1 to 8 to have excellent cleaning properties even in harsh environments. Therefore, the image forming apparatuses of Examples 1 to 8 can be effectively used as electrophotographic image forming apparatuses.

Although the embodiments have been described above, they are presented as examples, and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. are possible without departing from the gist of the invention. These embodiments and their variations are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

REFERENCE SIGNS LIST 1 cleaning blade 2 elastic member 4 image carrier 100 image forming apparatus (printer)

JP 2004-279591 A

Claims (8)

An image forming apparatus including a cleaning member and a cleaning unit that removes toner remaining on the cleaning member,
the cleaning unit includes a cleaning blade having an elastic member that comes into contact with a surface of the member to be cleaned to remove toner adhering to the surface of the member to be cleaned,
the elastic member has a tip edge portion that abuts against the member to be cleaned,
the elastic member contains a domain derived from a polysiloxane structure having an average dispersed diameter of 0.1 μm to 5.0 μm in a region from the surface including the tip ridge line to a depth of 100 μm,
The toner contains particles having a particle diameter of 3 μm or less at 20% by number or more. 2. The image forming apparatus according to claim 1, wherein the elastic member has a Martens hardness HM of 0.5 N/mm ² or more and less than 1.5 N/mm ² at a depth of 20 μm from the surface of the tip edge line portion. The image forming device according to claim 1 or 2, wherein the average dispersion diameter of the domains derived from the polysiloxane structure is 0.5 μm to 2.0 μm. The image forming device according to any one of claims 1 to 3, wherein the elastic member has a single-layer structure or a multi-layer structure. The image forming device according to any one of claims 1 to 4, wherein the toner contains 25% to 55% by number of particles having a particle diameter of 3 μm or less. An image carrier;
an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier;
a developing section for developing the electrostatic latent image with the toner to form a visible image;
a transfer section for transferring the visible image onto a recording medium;
a fixing section for fixing the transferred image onto the recording medium;
Equipped with
6. The image forming apparatus according to claim 1, wherein the member to be cleaned includes the image carrier. A cleaning step is included in which the toner remaining on the surface of the member to be cleaned is removed by a cleaning blade,
the cleaning blade has an elastic member that comes into contact with the surface of the member to be cleaned to remove toner adhering to the surface of the member to be cleaned,
the elastic member has a tip edge portion that abuts against the member to be cleaned,
the elastic member contains a domain derived from a polysiloxane structure having an average dispersed diameter of 0.1 μm to 5.0 μm in a region from the surface including the tip ridge line to a depth of 100 μm,
The toner contains particles having a particle diameter of 3 μm or less at 20% by number or more. forming an electrostatic latent image on an image carrier, developing the electrostatic latent image with the toner to form a visible image, transferring the visible image to a recording medium, and fixing the transferred image on the recording medium;
The image forming method according to claim 7 , wherein the member to be cleaned includes the image bearing member.

Images