JP2017116593A - Intermediate transfer body, image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate transfer body that has flexibility, is excellent in toner releasability, suppress the generation of unevenness in image density and white streaks, and ensures fire retardancy while maintaining high transferability in a high-temperature and high-humidity environment.SOLUTION: There is provided an intermediate transfer body comprising at least a base layer and a surface layer, where the surface layer includes a fire-retardant compound, and a crosslinked body of polyrotaxane including at least cyclic molecules, straight-chain molecules including the cyclic molecules in a skewered manner, and blockade groups that are arranged at both ends of the straight chain molecule and prevent isolation of the cyclic molecules; and the fire-retardant compound is a nitrogen-based compound.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an intermediate transfer member, an image forming apparatus, and an image forming method.

  Conventionally, in an electrophotographic image forming apparatus, a belt, particularly a seamless belt, is used as a member for various purposes. Particularly in recent full-color image forming apparatuses, an intermediate transfer belt system in which developed images of four colors of yellow, magenta, cyan, and black are once color-superposed on an intermediate transfer medium and then collectively transferred to a transfer medium such as paper. Is used.

  Such an intermediate transfer belt system has been used in a system that uses four color developing devices for one photoconductor, but has a drawback in that the printing speed is slow. For this reason, as a high-speed print, a four-tandem tandem method is used in which the photoreceptors are arranged for four colors and each color is continuously transferred to paper. However, in this method, there are fluctuations due to the environment of the paper, etc., and it is very difficult to match the position accuracy of overlapping each color image, causing a color misregistration image. Therefore, in recent years, it has become the mainstream to adopt the intermediate transfer method for the quadruple tandem method.

  Under such circumstances, the required characteristics (high-speed transfer, positional accuracy) of the intermediate transfer belt are also stricter than before, and it is necessary to satisfy the characteristics corresponding to these requirements. Yes. In particular, for positional accuracy, it is required to suppress fluctuation due to deformation such as elongation of the belt itself due to continuous use. Further, the intermediate transfer belt is laid out over a wide area of the apparatus, and is required to be flame retardant because a high voltage is applied for transfer. In order to meet such requirements, polyimide resins, polyamideimide resins, and the like that are high elastic modulus and high heat resistance resins are mainly used as intermediate transfer belt materials.

  However, since the intermediate transfer belt made of polyimide resin has high strength and high surface hardness, a high pressure is applied to the toner layer when the toner image is transferred, and the toner locally aggregates and a part of the image is formed. A so-called hollow image that is not transferred may occur. In addition, contact followability with a contact member at a transfer portion such as a photoreceptor or paper is inferior, so that a partial contact failure portion (gap) occurs in the transfer portion, and transfer unevenness may occur.

In recent years, full-color electrophotography has been used to form images on various types of paper. In addition to ordinary smooth paper, recycled paper and embossed paper can be used not only from smooth paper but also from slippery and highly smooth paper such as coated paper. Roughly surfaced materials such as Japanese paper and kraft paper are increasingly used. Such followability to papers having different surface properties is important. If the followability is poor, unevenness of the unevenness of the paper and unevenness of color tone occur.
In order to solve this problem, various intermediate transfer belts in which a relatively flexible elastic layer is laminated on a base layer have been proposed.

  In order to solve this problem, various intermediate transfer belts in which a relatively flexible elastic layer is laminated on a base layer have been proposed.

  However, when the surface layer is a relatively flexible layer, the transfer pressure is reduced and the followability to paper irregularities is improved, but the toner cannot be released well due to the poor surface releasability. There is a problem that transfer efficiency is lowered and the former effect cannot be utilized. There is also a problem that it is inferior in wear resistance and scratch resistance.

  In order to solve this problem, there is a method of newly providing a protective layer, but when coated with a material with sufficiently high transfer performance, there is a problem that the flexibility of the flexible layer cannot be followed and cracking or peeling occurs. It occurs and is not preferable.

  On the other hand, flame retardancy is required from the market for intermediate transfer belts used in image forming apparatuses. However, the intermediate transfer belt in which the relatively flexible layer as described above is laminated on the base layer has a problem that the flame retardancy is inferior. Moreover, it has been difficult to achieve both flame retardancy and transfer performance.

  In Patent Document 1, an intermediate transfer member has a two-layer structure in which a surface layer is laminated on a base layer, and an improvement in transferability is proposed by setting the outermost surface hardness higher. However, in the configuration of Patent Document 1, as described above, transferability to a paper having rough surface properties such as recycled paper, embossed paper, Japanese paper, and kraft paper is deteriorated due to poor followability. Moreover, it does not describe about the flame retardance of a member.

  Patent Document 2 reports that an electrophotographic member having a polyrotaxane as a surface layer is provided. However, when a flame retardant other than the nitrogen-based flame retardant is selected, it is necessary to add a large amount in order to exhibit flame retardancy, and the transfer performance gradually decreases with respect to the amount of flame retardant added. Furthermore, the addition of flame retardants often deteriorates transferability due to the influence of temperature and humidity, and this tendency is particularly noticeable in high-temperature and high-humidity environments. It wasn't done.

  The present invention has been made in view of the above-described prior art, is flexible and excellent in toner releasability, suppresses the occurrence of uneven image density and white spots, and has high transferability even in a high-temperature and high-humidity environment. An object of the present invention is to provide an intermediate transfer member that maintains flame retardancy while maintaining it.

  In order to solve the above problems, the present invention provides an intermediate transfer member having at least a base layer and a surface layer, wherein the surface layer includes at least a cyclic molecule, a linear molecule that includes the cyclic molecule in a skewered manner, and the surface layer. A crosslinked polyrotaxane having a blocking group disposed at both ends of the linear molecule and preventing the elimination of the cyclic molecule, and a flame retardant compound, wherein the flame retardant compound is a nitrogen-based compound It is characterized by that.

  According to the present invention, it has flexibility and excellent toner releasability, suppresses the occurrence of density unevenness and white spots in an image, and ensures flame retardancy while maintaining high transferability even in a high temperature and high humidity environment. An intermediate transfer member can be provided.

An example of a layer structure in the intermediate transfer member of the present invention is shown. It is a schematic diagram which shows notionally the basic structure in an example of the polyrotaxane of this invention. FIG. 2 is a schematic diagram of a main part of an example of an image forming apparatus equipped with the intermediate transfer member of the present invention as a belt member. FIG. 6 is a schematic diagram of a main part of another example of an image forming apparatus equipped with the intermediate transfer member of the present invention as a belt member.

  Hereinafter, an intermediate transfer member, an image forming apparatus, and an image forming method according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art, and any aspect is possible. As long as the functions and effects of the present invention are exhibited, the scope of the present invention is included.

  In an electrophotographic image forming apparatus, a seamless belt is used for several members. An intermediate transfer member (intermediate transfer belt) is an important member that requires electrical characteristics. Hereinafter, the intermediate transfer member of the present invention will be described.

  The present invention is an intermediate transfer member having at least a base layer and a surface layer, wherein the surface layer includes at least a cyclic molecule, a linear molecule that includes the cyclic molecule in a skewered manner, and both ends of the linear molecule. And a cross-linked polyrotaxane having a blocking group for preventing the elimination of the cyclic molecule, and a flame retardant compound, wherein the flame retardant compound is a nitrogen compound.

  The intermediate transfer member of the present invention is an intermediate transfer belt type image forming apparatus [so-called a plurality of color toner development images sequentially formed on an image carrier (for example, a photosensitive drum) are sequentially superimposed on the intermediate transfer belt. In this case, the intermediate transfer belt is suitably equipped with an apparatus that performs primary transfer and collectively transfers the primary transfer image onto a recording medium. FIG. 1 shows a layer structure of an intermediate transfer belt preferably used in the present invention. As a configuration, a flexible surface layer 102 is laminated on a rigid base layer 101 that can be relatively flexible.

  In the present invention, it is not always necessary to have a two-layer structure of a base layer and a surface layer, and an intermediate layer may be provided as necessary. Examples of the intermediate layer include a primer layer for improving adhesiveness and a relatively soft elastic layer such as elastomer or rubber for improving followability to a transfer medium.

<Base layer>
First, the base layer 101 will be described. Examples of the constituent material include a resin (or additive) that adjusts electric resistance in the resin, that is, a so-called electric resistance adjusting agent.
As such a resin, from the viewpoint of flame retardancy, for example, a fluorine-based resin such as PVDF (polyvinylidene fluoride) and ETFE (tetrafluoroethylene / ethylene copolymer), a polyimide resin, or a polyamide-imide resin is preferable. From the viewpoint of mechanical strength (high elasticity) and heat resistance, a polyimide resin or a polyamideimide resin is particularly preferable.

  Examples of the electrical resistance adjusting agent include metal oxide, carbon black, ionic conductive agent, and conductive polymer material. Examples of the metal oxide include zinc oxide, tin oxide, titanium oxide, zirconium oxide, aluminum oxide, and silicon oxide. Moreover, in order to improve dispersibility, the metal oxide may be subjected to surface treatment in advance. Examples of carbon black include ketjen black, furnace black, acetylene black, thermal black, and gas black. Examples of the ionic conductive agent include tetraalkylammonium salts, trialkylbenzylammonium salts, alkylsulfonates, alkylbenzenesulfonates, alkyl sulfates, glycerol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acids. Alcohol ester, alkyl betaine, lithium perchlorate, etc. are mentioned, and these may be used in combination.

In addition, the electrical resistance adjusting agent in this invention is not limited to the said exemplary compound.
In addition, the coating liquid containing at least the resin component in the method for producing a seamless belt of the present invention further contains additives such as a dispersion aid, a reinforcing agent, a lubricant, a heat conductive agent, and an antioxidant as necessary. May be.

The case of using a seamless belt is preferably equipped as an intermediate transfer belt, as a resistance value, preferably ^{1 × 10 8 ~1 × 10 13} Ω / □ in surface resistivity, 1 × 10 ⁸ to 1 volume resistivity The amount of carbon black to be × 10 ¹¹ Ω · cm is contained, but from the viewpoint of mechanical strength, a carbon black that can be achieved with an addition amount that is not brittle and does not easily break is selected. In other words, in the case of an intermediate transfer belt, an electrical characteristic (for example, a coating liquid in which the blending of the resin component (for example, a polyimide resin precursor or a polyamideimide resin precursor) and an electrical resistance adjuster is appropriately adjusted is used. It is preferable to manufacture and use a seamless belt having a balance between surface resistivity and volume resistivity) and mechanical strength.

  There is no restriction | limiting in particular as thickness of the base layer 101, Although it can select suitably according to the objective, 30 micrometers-150 micrometers are preferable, 40 micrometers-120 micrometers are more preferable, 50 micrometers-80 micrometers are especially preferable. When the thickness of the base layer 101 is 30 μm or more, the belt does not tear due to cracks, and when it is 150 μm or less, the belt does not crack due to bending. On the other hand, when the thickness of the base layer 101 is within the particularly preferable range, it is advantageous in terms of durability.

  The method for measuring the thickness of the base layer 101 is not particularly limited and can be appropriately selected depending on the purpose. For example, measurement with a contact-type or eddy-current film thickness meter or a cross-section of the film can be performed with a scanning electron. The method of measuring with a microscope (SEM) is mentioned.

  In the case of carbon black, the content of the electrical resistance adjusting agent in the present invention is 10 to 25% by mass, preferably 15 to 20% by mass, based on the total solid content in the coating liquid. Moreover, as content in the case of a metal oxide, it is 1-50 mass% of the total solid of a coating liquid, Preferably it is 10-30 mass%. If the content is less than the range of the respective electric resistance adjusting agents, it becomes difficult to obtain uniformity of resistance value, and the fluctuation of the resistance value with respect to an arbitrary potential may increase. On the other hand, when the content is larger than the above ranges, the mechanical strength of the intermediate transfer belt is lowered, which is not preferable in actual use.

  As polyimide and polyamideimide in the present invention, manufacturers such as Toray DuPont, Ube Industries, Shin Nippon Chemical, JSR, Unitika, IST, Hitachi Chemical, Toyobo, Arakawa Chemical General-purpose products from can be obtained and used.

<Surface>
Next, the surface layer 102 laminated on the base layer 101 will be described. The surface layer is a crosslinked polyrotaxane having at least a cyclic molecule, a linear molecule that includes the cyclic molecule in a skewered manner, and a blocking group that is disposed at both ends of the linear molecule to prevent the elimination of the cyclic molecule. And a flame retardant compound.

  The surface layer can be made to have a hardness suitable for transferability by crosslinking with a curing agent so as to keep the flexibility of the polyrotaxane moderately.

<Crosslinked polyrotaxane>
A crosslinked polyrotaxane is obtained by mixing a polyrotaxane and a curing agent (crosslinking agent).

<Polyrotaxane>
FIG. 2 is a schematic diagram conceptually showing the basic structure of the polyrotaxane used in the present invention. Here, rotaxane refers to a molecule in which a cyclic molecule is inserted into a dumbbell-shaped linear upper axis molecule. By using a polymer such as polyethylene glycol as the axis molecule, a cyclic molecule such as cyclodextrin is formed. The one confined in plural is called polyrotaxane. Dumbbell-shaped portions at both ends play a role of preventing the elimination of the cyclic molecule, that is, a blocking group. In addition, the dumbbell-shaped linear molecule having blocking groups at both ends is not covalently bonded to the cyclic molecule.

  Therefore, the linear molecule can freely move in the hole of the cyclic molecule, and the cyclic molecule can also move along the linear molecule.

  Further, either one or both of a linear molecule and a cyclic molecule constituting the polyrotaxane may have a lipophilic modification group. As a result, it becomes easy to dissolve in an organic solvent and to be easily applied as a surface layer.

  In the present invention, lipophilic modified polyrotaxane is preferred. Here, the lipophilic modified polyrotaxane refers to a polyrotaxane in which either one or both of a linear molecule and a cyclic molecule have a lipophilic modification group. Examples of the modifying group exhibiting lipophilicity include an alkyl group and a benzyl group.

  In FIG. 2, the lipophilic modified polyrotaxane 1 has a linear molecule 2, a cyclic molecule 3, and a blocking group 4 disposed at both ends of the linear molecule. Here, for example, when the cyclic molecule is a cyclodextrin, the blocking group 4 needs to be sufficiently bulky so that the cyclodextrin molecule cannot be detached from the linear molecule 2 which is the chain polymer molecule having the terminal functional group. There is. The linear molecule 2 penetrates the hole (opening) of the cyclic molecule 3 and is included by the cyclic molecule 3, and the cyclic molecule 3 preferably has a lipophilic modification group 3A. That is, when stress is applied, the cyclic molecule 3 can move freely along the linear molecule 2 like a pulley. As a result, the stretchability and flexibility are excellent, and the followability to the transfer medium is improved.

  Here, the linear molecule may be substantially linear, and any molecule having a reactive functional group capable of binding a blocking group at its end can be used without any limitation. . For example, the linear molecule includes polyethylene glycol, and the blocking group includes an adamantane group.

  The linear molecule 2 having a terminal functional group preferably has a molecular weight of 1,000 to 50,000, more preferably 10,000 to 40,000, and more preferably 20,000 to 35,000. A range is particularly preferred.

  When the molecular weight of the linear molecule is 1,000 or more, the pulley effect by the cyclic molecule is sufficiently obtained, the flexibility of the coating film is not lowered, and the scratch resistance and the followability to the transfer medium are deteriorated. There is nothing to do. When the molecular weight is 50,000 or less, the viscosity of the coating liquid does not become too high, and appearance deterioration such as smoothness and gloss does not occur.

<Cyclic molecule>
The cyclic molecule in the polyrotaxane can be used without any limitation as long as it can move through the chain molecule in the ring. Further, the cyclic molecule is not necessarily completely closed, and a part of the ring may be opened to the extent that it does not leave the chain molecule.

  Furthermore, as the cyclic molecule, those having a reactive group are preferable in that the binding with the above-described lipophilic modification group is facilitated. Examples of such a reactive group include a hydroxyl group, a carboxyl group, an amino group, and the like, but the reactive group does not react with the blocking group when forming the blocking group. Those having the following are preferred.

  As the cyclic molecule, any cyclic molecule can be used without any limitation as long as the cyclic molecules are not cross-linked and can pass a chain polymer molecule into the ring. Suitable cyclic molecules include cyclodextrins and crown ethers. Among these, cyclodextrins are particularly preferable because they can easily form an inclusion compound with an organic compound.

Cyclodextrins are compounds in which a plurality of glucoses are linked in a cyclic manner with α-1,4-bonds. Among them, compounds formed with 6, 7, and 8 glucoses are α-, β-, And γ-cyclodextrin, and more preferably used. From the viewpoint of inclusion, α-cyclodextrin is preferably used.
In addition, modified dextrins in which at least one of the hydroxyl groups of these cyclodextrins is substituted with another organic functional group are more preferably used in terms of improving the solubility in a solvent.

  The above-mentioned cyclic molecules such as cyclodextrin can be used alone or in combination of two or more. In addition, the number (inclusion amount) of the cyclic molecule included in the linear molecule may be arbitrarily set as long as the cyclic molecule itself is within a range in which the linear molecule can move freely like a pulley. Absent.

<Preferred examples of polyrotaxane>
A polyrotaxane suitable for the present invention includes a cyclic molecule, a linear molecule that includes the cyclic molecule in a skewered manner, and a blocking group that is disposed at both ends of the linear molecule and prevents the cyclic molecule from detaching. Wherein the blocking group is an adamantane group, the cyclic molecule is α-cyclodextrin, part or all of the hydroxyl group of the cyclodextrin is modified with a modifying group, and the modifying group is —C ₃ H ₆ — It has a structure having a (—CO (CH ₂ ) ₅ OH) group, which is a modified group by caprolactone, bonded to an O— group.

  In addition, the polyrotaxane in the present invention described above can be produced by a known method, for example, the method of Japanese Patent No. 437649, or a general-purpose product from a manufacturer such as Advanced Soft Materials is used and used. You can also.

  The surface layer of the intermediate transfer member of the present invention contains a crosslinked polyrotaxane. The cross-linked polyrotaxane means a product obtained by cross-linking the above-mentioned polyrotaxane alone with another polymer. That is, in the surface layer of the intermediate transfer member of the present invention, the curing agent that forms the surface layer is bonded to the polyrotaxane through the cyclic portion of the polyrotaxane that also forms the surface layer. With this crosslinked polyrotaxane, excellent transferability can be achieved.

<Curing agent (crosslinking agent)>
Next, the curing agent (crosslinking agent) will be described. Curing agents used in the present invention may be those that are currently on the market and are not particularly limited, but are preferably suitably used so that the surface layer has a preferable hardness for transferability while maintaining the flexibility of the polyrotaxane appropriately. Choose one.

  The surface layer in the present invention can be obtained by dissolving the polyrotaxane in an organic solvent, adding a curing agent, coating, drying and copolymerizing.

  Specific examples of the crosslinking agent (curing agent) include polyisocyanate compounds, blocked isocyanate compounds, cyanuric chloride, trimesoyl chloride, terephthaloyl chloride, epichlorohydrin, dibromobenzene, glutaraldehyde, phenylene diisocyanate, diisocyanic acid. Examples include trilein, divinylsulfone, 1,1′-carbonyldiimidazole, and alkoxysilanes. In the present invention, these can be used singly or in combination of two or more, but isocyanate is preferable from the viewpoint of easy crosslinking, and among them, hexamethylene diisocyanate polyisocyanate is preferable. Hexamethylene diisocyanate is highly reactive because it has two primary isocyanate groups, and less uncrosslinked OH groups, so that the intermediate transfer member obtained by crosslinking it has excellent toner releasability, and hexamethylene diisocyanate. Since methylene diisocyanate has six methylene groups between isocyanate groups, the flexibility of an intermediate transfer member obtained by crosslinking the methylene groups is excellent, and therefore, transferability is improved, so that transferability is more preferable.

  Further, blocked isocyanate is more preferable because of high storage stability at room temperature. Block isocyanate protects active isocyanate groups with blocking agents such as oximes, diketones, phenols, caprolactams, etc., maintains stability under normal conditions, dissociates the blocking agent by heat treatment, and regenerates active isocyanate groups It causes a curing / crosslinking reaction. The isocyanate preferably used in the present invention is a blocked isocyanate of hexamethylene diisocyanate polyisocyanate.

  Moreover, you may use the general-purpose goods currently marketed as an isocyanate type hardening | curing agent. For example, “Duranate” manufactured by Asahi Kasei Chemicals, “Takenate” manufactured by Mitsui Chemicals, “Coronate” manufactured by Nippon Polyurethane Industry Co., Ltd., “Desmodule” manufactured by Sumika Bayer Urethane Co., Ltd., etc. are available from the market.

<Flame retardant compound>
Next, the flame retardant compound will be described. As the flame retardant compound used in the present invention, a nitrogen-based compound that is stable with respect to temperature and humidity is used. Speaking of flame retardant compounds in general, halogen flame retardants and phosphorus flame retardants have a great effect on flame retardancy, but they are unstable to changes in temperature and humidity, so transfer performance tends to vary. Therefore, it is not preferable.
Of the nitrogen compounds preferably used in the present invention, melamine salts of inorganic acids are particularly preferred. An inorganic acid is a term for an organic acid, and is an acid formed by combining an acid group containing a nonmetal such as chlorine, sulfur, nitrogen, or phosphorus with hydrogen. Specific examples include hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid, phosphoric acid, boric acid, polyphosphoric acid, carbonic acid, silicic acid, and aluminate. Of these, sulfuric acid, polyphosphoric acid, and boric acid are preferable.

  Specific examples of the nitrogen-based compounds described above include ammonium sulfate, melamine, melamine sulfate, melamine polyphosphate, melamine borate, acetoguanamine, benzoguanamine, melon, melam, succinoguanamine, ethylene dimelamine, guanylmelamine sulfate, and melem sulfate. , Melam sulfate, mono (hydroxymethyl) melamine, di (hydroxymethyl) melamine, tri (hydroxymethyl) melamine, melamine cyanurate, cyanurate, 2-amido-4,6-diamino-1,3,5-triazine, melamine Examples include phosphate. Among these, melamine sulfate is particularly preferable in terms of flame retardancy, transferability, and temperature and humidity stability (transferability at high temperature and high humidity does not deteriorate). These flame retardant compounds may be used alone or in combination of two or more as required.

  In blending the flame retardant compound into the resin, there are a method of directly mixing and a method of mixing after dissolving or dispersing in a solvent. When the primary particle size of the flame retardant compound is large, the effect of the present invention is obtained. Since it is not sufficiently exerted, it is necessary to pulverize or disperse to a predetermined particle size. In the present invention, the flame-retardant compound preferably has a volume average particle size of 10 μm or less, more preferably 3 μm or less.

  In the pulverization step, the method is not particularly limited, and examples thereof include a method of mechanically pulverizing using a large mixer or the like, or dispersing with a commonly used disperser such as a ball mill, apex mill, roll mill, and sand mill. . Among these, high-speed sand mills are preferable. For example, when using a super mill, sand grinder, bead mill, agitator mill, glen mill, dyno mill, pearl mill, cobol mill (all of which are trade names), the particle size can be reduced in a shorter time. it can.

  Here, in order to measure the particle diameter of the flame-retardant compound that has been atomized, a sample diluted with a dispersion solvent can be measured with a particle size analyzer (for example, Microtrack UPA manufactured by Nikkiso Co., Ltd.).

  The amount of the flame retardant compound finely divided can be appropriately selected depending on the required flame retardancy, but is preferably 10 to 100 parts by weight, more preferably 20 to 50 parts by weight with respect to 100 parts by weight of the polyrotaxane. Part. When the amount is more than 100 parts by weight, the flexibility of the film is impaired. On the other hand, if the blending amount is less than 10 parts by weight, it is not preferable because sufficient flame retardancy cannot be exhibited.

  The flame retardancy of the flame retardant compound-blended film of the present invention can be evaluated based on the UL94-VTM test and UL94-V test (thin material vertical combustion test).

  In the UL94-VTM test, a film test piece (200 ± 5 × 50 ± 1 × t mm) is wound into a cylindrical shape, mounted vertically on a clamp, and subjected to a 3 second indirect flame with a 20 mm flame twice. -0, VTM-1, VTM-2, and NOT are determined.

  In addition, when the thickness of the test piece is 250 μm or more, the flammability is examined by the UL94-V test. In the UL94-V test, a film test piece (125 ± 5 × 13 ± 0.5 × t mm) is vertically attached to the clamp, and 10 seconds of indirect flame with 20 mm flame is performed twice, and V-0, V-1, V-2, and NOT are determined.

  Flame retardancy is represented by good: VTM-0 (V-0)> VTM-1 (V-1)> VTM-2 (V-2)> NOT: nonconformity. Table 1 shows the criteria.

<Preparation of intermediate transfer belt>
Next, an example of a method for producing the belt having the configuration of the present invention will be described. First, a method for manufacturing the base layer 101 will be described.

<< Base layer >>
A method for producing the base layer 101 using a coating solution containing at least a resin component, that is, a coating solution containing a polyimide resin precursor or a polyamideimide resin precursor will be described. The base layer can be produced by applying the coating solution by a known method such as spiral coating, die coating, or roll coating.

  While slowly rotating a cylindrical mold, for example, a cylindrical metal mold, a coating liquid containing at least a resin component (for example, a coating liquid containing a polyimide resin precursor or a polyamideimide resin precursor) is used as a nozzle or Application and casting (formation of a coating film) is performed uniformly on the entire outer surface of the cylinder by a liquid supply device such as a dispenser. Thereafter, the rotation speed is increased to a predetermined speed, and when the predetermined speed is reached, the rotation speed is maintained at a constant speed and the rotation is continued for a desired time. And the solvent in a coating film is evaporated at the temperature of about 80-150 degreeC, heating up gradually while rotating. In this process, it is preferable to efficiently circulate and remove atmospheric vapor (such as a volatilized solvent). When a self-supporting film is formed, the mold is transferred to a heating furnace (firing furnace) capable of high-temperature processing, and the temperature is raised stepwise, and finally high-temperature heat processing (firing is performed at about 250 ° C. to 450 ° C. ) To sufficiently imidize or polyamide-imide the polyimide resin precursor or polyamide-imide resin precursor. After sufficiently cooling, the surface layer 102 is subsequently laminated.

<< surface layer >>
As the surface layer 102, a surface layer coating solution in which at least a polyrotaxane, a curing agent (crosslinking agent), and a flame retardant compound are dissolved in an organic solvent is used.

-Surface coating liquid-
When the polyrotaxane and the curing agent are cross-linked, the mixing ratio of the polyrotaxane and the curing agent is such that the equivalent ratio of the reactive group of the curing agent that reacts with the OH group of the polyrotaxane and the OH group is reactive group / OH group = 0.5 to 3.0. It is preferable to adjust so that. More preferably, the equivalent ratio is adjusted so that reactive groups / OH groups = 1.0 to 1.2. For example, when the curing agent is an isocyanate, the blending ratio of the polyrotaxane and the isocyanate is preferably adjusted so that NCO / OH = 0.5 to 3.0. More preferably, the equivalent ratio is adjusted by NCO / OH = 1.0 to 1.2.

  If the equivalent ratio is less than 0.5, it is difficult to sufficiently perform crosslinking, and it may be difficult to maintain the shape of the crosslinked product. On the other hand, if the equivalent ratio is larger than 3.0, the crosslinked product becomes too hard, and the flexibility as the surface layer may be impaired.

-Production of surface layer-
The surface layer can be produced by coating and forming the above surface layer coating solution on the base layer, and then drying and curing (crosslinking) the solvent. As with the base layer, existing coating methods such as spiral coating, die coating, roll coating, or spray coating can be applied as with the base layer, but as with the base layer, a cylindrical metal mold is slowly rotated. Then, coating and casting (forming a coating film) are performed uniformly on the entire outer surface of the cylinder by a liquid supply device such as a nozzle or a dispenser. Subsequently, leveling is performed by maintaining a predetermined rotation speed and drying temperature. During rotation, heating may be performed as necessary. A seamless belt can be obtained by such a production method.

  It should be noted that the above-mentioned selected material has a resistance adjuster for adjusting electric characteristics, and further contains a composition such as an antioxidant, a reinforcing agent, a filler, a vulcanization accelerator, and a plasticizer as necessary. You can go.

  The said surface layer coating liquid can be made into a crosslinked material by heating. The heating temperature is preferably 130 ° C. to 220 ° C., more preferably 140 ° C. to 200 ° C., and the crosslinking time is preferably 30 minutes to 3 hours. As a heating method, a known method such as press heating, steam heating, oven heating, hot air heating or the like may be appropriately selected.

  Further, the film thickness of the surface layer is preferably 30 μm to 300 μm, more preferably 50 μm to 200 μm. When the thickness is 30 μm or more, the image quality for a paper type having surface irregularities is sufficient. On the other hand, when the thickness is 300 μm or less, the film becomes heavier due to the increased weight of the film, the warpage increases, the running performance becomes unstable, and the bending at the roller curvature for stretching the belt. This is preferable because cracks do not easily occur. In addition, as a measuring method of the said thickness, a cross section can be measured with a scanning microscope (SEM).

<Image Forming Apparatus and Image Forming Method>
An image forming apparatus according to the present invention includes an image carrier on which a latent image is formed and can carry a toner image, a developing unit that develops the latent image formed on the image carrier with toner, and the developing unit. An intermediate transfer body on which the developed toner image is primarily transferred; and transfer means for secondary transfer of the toner image carried on the intermediate transfer body to a recording medium. Including, for example, a static eliminating unit, a cleaning unit, a recycling unit, a control unit, and the like. In this case, it is preferable that the image forming apparatus is a full-color image forming apparatus in which a plurality of image carriers having developing units for respective colors are arranged in series.

  The image forming method of the present invention includes a latent image forming step for forming a latent image on an image carrier, and development for forming a toner image by developing the latent image formed on the image carrier with toner. An intermediate transfer step for primary transfer of the toner image developed in the development step to an intermediate transfer member, and a transfer step for secondary transfer of the toner image carried on the intermediate transfer member to a recording medium. In addition, other processes appropriately selected as necessary, for example, a static elimination process, a cleaning process, a recycling process, a control process, and the like are included.

  The seamless belt used in the belt constituting unit provided in the image forming apparatus according to the present invention will be described in detail below with reference to a schematic diagram of the relevant part. The schematic diagram is an example, and the present invention is not limited to this.

FIG. 3 is a schematic view of a main part for explaining an image forming apparatus equipped with an intermediate transfer member, which is a seamless belt obtained by the manufacturing method according to the present invention, as a belt member.
The intermediate transfer unit 500 including the belt member shown in FIG. 3 includes an intermediate transfer belt 501 that is an intermediate transfer member stretched around a plurality of rollers. Around the intermediate transfer belt 501, a secondary transfer bias roller 605 that is a secondary transfer charge applying unit of the secondary transfer unit 600, a belt cleaning brush 504 that is an intermediate transfer member cleaning unit, and a lubricant for a lubricant application unit. A lubricant application brush 505 or the like that is an application member is disposed so as to face each other.

  A position detection mark (not shown) is provided on the outer peripheral surface or inner peripheral surface of the intermediate transfer belt 501. However, on the outer peripheral surface side of the intermediate transfer belt 501, it is necessary to devise a position detection mark that avoids the passing area of the belt cleaning brush 504, which may be difficult to arrange. A position detection mark may be provided on the inner peripheral surface side of the intermediate transfer belt 501. An optical sensor 514 serving as a mark detection sensor is provided at a position between the primary transfer bias roller 507 and the belt driving roller 508 where the intermediate transfer belt 501 is bridged.

  The intermediate transfer belt 501 includes a primary transfer bias roller 507, a belt driving roller 508, a belt tension roller 509, a secondary transfer counter roller 510, a cleaning counter roller 511, and a feedback current detection roller 512, which are primary transfer charge applying units. It is stretched around. Each roller is formed of a conductive material, and each roller other than the primary transfer bias roller 507 is grounded. The primary transfer bias roller 507 is applied with a transfer bias controlled to a predetermined current or voltage according to the number of superimposed toner images by a primary transfer power source 801 controlled at a constant current or voltage. ing.

The intermediate transfer belt 501 is driven in the arrow direction by a belt driving roller 508 that is driven to rotate in the arrow direction by a drive motor (not shown).
The intermediate transfer belt 501 as a belt member is usually a semiconductor or an insulator and has a single layer or a multilayer structure. However, in the present invention, a seamless belt is preferably used, and this improves durability. Excellent image formation can be realized. Further, the intermediate transfer belt is set to be larger than the maximum sheet passing size in order to superimpose toner images formed on the photosensitive drum 200 as an image carrier.

  A secondary transfer bias roller 605 serving as a secondary transfer unit is attached to and separated from a belt outer peripheral surface of the intermediate transfer belt 501 in a portion stretched around the secondary transfer counter roller 510 by a contact / separation mechanism, which will be described later. It is configured to be able to contact and separate. The secondary transfer bias roller 605 is disposed so as to sandwich the transfer paper P, which is a recording medium, between the portion of the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 and a constant current. A transfer bias having a predetermined current is applied by a secondary transfer power source 802 to be controlled.

  The registration roller 610 feeds the transfer sheet P, which is a transfer material, between the secondary transfer bias roller 605 and the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 at a predetermined timing. The secondary transfer bias roller 605 is in contact with a cleaning blade 608 as a cleaning unit. The cleaning blade 608 is for removing the adhering matter adhering to the surface of the secondary transfer bias roller 605 for cleaning.

  In the color copying machine having such a configuration, when an image forming cycle is started, the photosensitive drum 200 is rotated in a counterclockwise direction indicated by an arrow by a drive motor (not shown), and Bk ( Black) toner image formation, C (cyan) toner image formation, M (magenta) toner image formation, and Y (yellow) toner image formation are performed. The intermediate transfer belt 501 is rotated clockwise by the belt driving roller 508 as indicated by an arrow. As the intermediate transfer belt 501 rotates, the primary transfer of the Bk toner image, the C toner image, the M toner image, and the Y toner image is performed by the transfer bias by the voltage applied to the primary transfer bias roller 507. Finally, the respective toner images are formed on the intermediate transfer belt 501 in the order of Bk, C, M, and Y.

  For example, the Bk toner image formation is performed as follows. In FIG. 3, a charging charger 203 uniformly charges the surface of the photosensitive drum 200 to a predetermined potential with a negative charge by corona discharge. The timing is determined based on the belt mark detection signal, and raster exposure with laser light is performed based on the Bk color image signal by a writing optical unit (not shown). When this raster image is exposed, the charge proportional to the exposure light amount disappears in the exposed portion of the surface of the photosensitive drum 200 that is initially uniformly charged, and a Bk electrostatic latent image is formed. When the negatively charged Bk toner on the developing roller of the Bk developing device 231K comes into contact with this Bk electrostatic latent image, the toner does not adhere to the remaining portion of the photosensitive drum 200, and the charge is not charged. The toner is attracted to the nonexposed portion, that is, the exposed portion, and a Bk toner image similar to the electrostatic latent image is formed.

  The Bk toner image formed on the photosensitive drum 200 in this manner is primarily transferred onto the belt outer peripheral surface of the intermediate transfer belt 501 that is rotating at a constant speed while being in contact with the photosensitive drum 200. Some untransferred residual toner remaining on the surface of the photoreceptor drum 200 after the primary transfer is cleaned by the photoreceptor cleaning device 201 in preparation for reuse of the photoreceptor drum 200. On the photosensitive drum 200 side, the process proceeds to the C image forming process after the Bk image forming process, and reading of C image data by a color scanner starts at a predetermined timing. By writing laser light with the C image data, the photosensitive drum A C electrostatic latent image is formed on the surface of 200.

  Then, after the rear end portion of the previous Bk electrostatic latent image passes and before the front end portion of the C electrostatic latent image arrives, the revolver developing unit 230 is rotated, and the C developing machine 231C develops. The C electrostatic latent image is developed with C toner. Thereafter, the development of the C electrostatic latent image area is continued. When the rear end of the C electrostatic latent image passes, the revolver developing unit is rotated in the same manner as in the case of the previous Bk developing machine 231K. The M developing machine 231M is moved to the developing position. This is also completed before the leading edge of the next Y electrostatic latent image reaches the developing position. Note that the M and Y image forming steps are the same as the Bk and C steps described above because the operations of reading color image data, forming an electrostatic latent image, and developing are the same as those described above. Reference numeral 231Y denotes a Y developing machine.

  The Bk, C, M, and Y toner images sequentially formed on the photosensitive drum 200 in this manner are sequentially aligned on the same surface on the intermediate transfer belt 501 and primarily transferred. As a result, a toner image having a maximum of four colors superimposed on the intermediate transfer belt 501 is formed. On the other hand, at the time when the image forming operation is started, the transfer paper P is fed from a paper feed unit such as a transfer paper cassette or a manual feed tray, and is waiting at the nip of the registration roller 610.

  When the leading edge of the toner image on the intermediate transfer belt 501 reaches the secondary transfer portion where the nip is formed by the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 and the secondary transfer bias roller 605. Then, the registration roller 610 is driven so that the leading edge of the transfer paper P coincides with the leading edge of the toner image, and the transfer paper P is conveyed along the transfer paper guide plate 601, and the transfer paper P and the toner image are transferred. Resist alignment is performed.

  In this way, when the transfer paper P passes through the secondary transfer portion, the four-color superimposed toner image on the intermediate transfer belt 501 is transferred by the transfer bias applied by the secondary transfer power source 802 to the secondary transfer bias roller 605. Are collectively transferred (secondary transfer) onto the transfer paper P. After the transfer paper P is conveyed along the transfer paper guide plate 601 and passed through a portion facing the transfer paper neutralization charger 606 composed of a static elimination needle disposed on the downstream side of the secondary transfer portion, the transfer paper P is discharged. Then, the toner is fed toward the fixing device 270 by the belt conveyance device 210 which is a belt component.

  Then, after the toner image is melted and fixed at the nip portions of the fixing rollers 271 and 272 of the fixing device 270, the transfer paper P is sent out of the apparatus main body by a discharge roller (not shown), and is stacked face up on a copy tray (not shown). Is done. Note that the fixing device 270 may be configured to include a belt component if necessary.

  On the other hand, the surface of the photosensitive drum 200 after the belt transfer is cleaned by the photosensitive member cleaning device 201 and is uniformly discharged by the discharging lamp 202. Further, residual toner remaining on the outer peripheral surface of the intermediate transfer belt 501 after the toner image is secondarily transferred to the transfer paper P is cleaned by the belt cleaning brush 504. The belt cleaning brush 504 is configured to contact and separate at a predetermined timing with respect to the belt outer peripheral surface of the intermediate transfer belt 501 by a cleaning member separating and contacting mechanism (not shown).

  On the upstream side of the belt cleaning brush 504 in the movement direction of the intermediate transfer belt 501, a toner seal member 502 that is in contact with and away from the outer peripheral surface of the intermediate transfer belt 501 is provided. The toner seal member 502 receives the falling toner that has dropped from the belt cleaning brush 504 during the cleaning of the residual toner, and prevents the falling toner from being scattered on the transfer path of the transfer paper P. The toner seal member 502 is brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt 501 together with the belt cleaning brush 504 by the cleaning member separating and contacting mechanism.

  The lubricant 506 scraped by the lubricant application brush 505 is applied to the outer peripheral surface of the intermediate transfer belt 501 from which the residual toner has been removed in this way. The lubricant 506 is made of, for example, a solid body such as zinc stearate, and is disposed so as to come into contact with the lubricant application brush 505.

  Further, residual charges remaining on the outer peripheral surface of the intermediate transfer belt 501 are removed by a neutralizing bias applied by a belt neutralizing brush (not shown) that is in contact with the outer peripheral surface of the intermediate transfer belt 501. Here, the lubricant application brush 505 and the belt neutralizing brush are brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing by respective contact and separation mechanisms (not shown). .

  Here, at the time of repeat copy, the operation of the color scanner and the image formation on the photosensitive drum 200 are performed at a predetermined timing following the first color (Y) image formation process of the first sheet and the first color of the second sheet. The process proceeds to the image forming process (Bk). Further, the intermediate transfer belt 501 has a second Bk toner in the area cleaned by the belt cleaning brush 504 on the outer peripheral surface of the belt following the batch transfer process of the first four-color superimposed toner image to the transfer paper. The image is first transferred. After that, the operation is the same as the first sheet. The above is a copy mode for obtaining a four-color full-color copy. In the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. In the single color copy mode, only the predetermined color developing machine of the revolver developing unit 230 is set in the developing operation state until the predetermined number of sheets is completed, and the belt cleaning brush 504 is kept in contact with the intermediate transfer belt 501. The copy operation is performed in the state.

  In FIG. 3, reference numeral 70 denotes a static elimination roller, 204 denotes a potential sensor, 205 denotes an image density sensor, 503 denotes a charging charger, 513 denotes a toner image, and L denotes laser light (emitted from laser exposure means).

  In the above-described embodiment, the copying machine including only one photosensitive drum 200 has been described. However, the present invention includes, for example, a plurality of photosensitive drums as illustrated in a schematic diagram of a main part in FIG. The present invention can also be applied to an image forming apparatus arranged side by side along one intermediate transfer belt formed of a seamless belt.

  The schematic diagram of the main part of FIG. 4 shows an example of a full-color image forming apparatus in which a plurality of image carriers are arranged in parallel along the intermediate transfer belt of the present invention. That is, FIG. 4 shows a four-drum type digital color printer having four photosensitive drums 21BK, 21Y, 21M, and 21C for forming toner images of four different colors (black, yellow, magenta, and cyan). A configuration example is shown.

  In FIG. 4, the printer body 10 includes an image writing unit 12, an image forming unit 13, and a paper feeding unit 14 for performing color image formation by an electrophotographic method. Based on the image signal, the image processing unit converts the image into black (BK), magenta (M), yellow (Y), and cyan (C) color signals for image formation and transmits them to the image writing unit 12. To do. The image writing unit 12 is a laser scanning optical system including, for example, a laser light source, a deflector such as a rotary polygon mirror, a scanning imaging optical system, and a mirror group. Image writing corresponding to each color signal is performed on image carriers (photoconductors) 21BK, 21M, 21Y, and 21C that have a writing optical path and are provided for each color of the image forming unit 13.

The image forming unit 13 includes photoconductors 21BK, 21M, 21Y, and 21C that are image carriers for black (BK), magenta (M), yellow (Y), and cyan (C). As each photoconductor for each color, an OPC photoconductor is usually used. Around the photoreceptors 21BK, 21M, 21Y, and 21C, there are a charging device, an exposure unit for laser light from the image writing unit 12, and developing devices 20BK, 20M, and 20Y for black, magenta, yellow, and cyan colors. 20C, primary transfer bias rollers 23BK, 23M, 23Y, and 23C as primary transfer means, a cleaning device (not shown), a photosensitive member static elimination device (not shown), and the like. The developing devices 20BK, 20M, 20Y, and 20C use a two-component magnetic brush developing system.
The intermediate transfer belt 22, which is a belt component, is interposed between the photosensitive members 21BK, 21M, 21Y, and 21C and the primary transfer bias rollers 23BK, 23M, 23Y, and 23C, and is formed on the photosensitive members. The toner images of each color are sequentially superimposed and transferred.

  On the other hand, the transfer paper P is fed from the paper feed unit 14 and then carried by the transfer conveyance belt 50, which is a belt component, via the registration roller 16. When the intermediate transfer belt 22 and the transfer conveyance belt 50 come into contact, the toner image transferred onto the intermediate transfer belt 22 is subjected to secondary transfer (collective transfer) by a secondary transfer bias roller 60 as a secondary transfer unit. ) As a result, a color image is formed on the transfer paper P. The transfer paper P on which the color image is formed is conveyed to the fixing device 15 by the transfer conveying belt 50, and after the image transferred by the fixing device 15 is fixed, it is discharged out of the printer main body.

  The residual toner that is not transferred during the secondary transfer and remains on the intermediate transfer belt 22 is removed from the intermediate transfer belt 22 by the belt cleaning member 25. A lubricant application device 27 is disposed on the downstream side of the belt cleaning member 25. The lubricant application device 27 includes a solid lubricant and a conductive brush that rubs the intermediate transfer belt 22 to apply the solid lubricant. The conductive brush is always in contact with the intermediate transfer belt 22 and applies a solid lubricant to the intermediate transfer belt 22. The solid lubricant has an effect of improving the cleaning property of the intermediate transfer belt 22, preventing the occurrence of filming, and improving the durability. In FIG. 4, reference numeral 26 denotes a driving roller, and 70 denotes a bias roller.

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited by these examples, and these examples are appropriately modified without departing from the gist of the present invention. Is also within the scope of the present invention.
In addition, the film thickness of each of the base layer and the surface layer of the belt was measured by observing cross sections at arbitrary 10 positions with a scanning electron microscope (SEM), and taking the average value. Unless otherwise specified, “parts” means “parts by mass”. Moreover, solid content ratio is shown on a mass basis.
Moreover, about a flame retardance test, in order to clarify the effect of a flame retardance film in each Example and a comparative example, the test piece of length 200mm and width 50mm was cut out as a test film, and for a flame retardance test Five pieces were made. About other conditions and evaluation, it carried out based on UL94-VTM test (thin material vertical combustion test). In addition, when the thickness of the produced belt was 0.25 mm or more (250 μm or more), the combustibility was examined by UL94-V test.
The particle size of the flame retardant compound was determined by measuring a sample obtained by diluting the flame retardant compound with a dispersion solvent (cyclohexanone) using a Microtrac UPA manufactured by Nikkiso Co., Ltd.

Example 1
A base layer coating solution was prepared as follows, and a seamless belt base layer was prepared using this coating solution.

<Preparation of base layer coating solution A>
First, polyimide varnish (U-varnish A and U-varnish S are mixed at a solid content ratio of 6: 4; manufactured by Ube Industries Co., Ltd.) mainly composed of a polyamic acid, which is a polyimide resin precursor, is previously N- A dispersion of carbon black (Special Black 4; manufactured by Orion Engineered Carbons) dispersed in methyl-2-pyrrolidone was prepared so that the carbon black content was 17% by mass of the polyamic acid solid content, and stirred well. By mixing, a base layer coating solution A was prepared.

<Preparation of polyimide base belt A>
Next, a metal cylindrical support whose outer surface is 375 mm in length and 340 mm in length is roughened by blasting is used as a mold, and the coating is performed while rotating the cylinder at 50 rpm (times / minute). The working liquid was applied with a dispenser so as to be uniformly cast on the outer surface of the cylinder. When the predetermined amount was completely poured and the coating film was spread evenly, the number of revolutions was increased to 100 rpm, introduced into a hot air circulating dryer, gradually heated to 110 ° C. and heated for 60 minutes. Further, the temperature is raised and heated at 200 ° C. for 20 minutes, the rotation is stopped, and it is slowly cooled to take out the cylindrical mold on which the formed film is formed, and this is introduced into a heating furnace (firing furnace) capable of high-temperature processing. Specifically, the temperature was raised to 360 ° C. and heat treatment (firing) was performed for 60 minutes. After sufficiently cooling, a polyimide base layer belt A having a film thickness of 60 μm was obtained.

<Preparation of surface coating liquid A>
First, “Celum Superpolymer SH3400P (manufactured by Advanced Soft Materials)”, a polyrotaxane, which is a cyclodextrin having a polyethylene glycol as a linear molecule, an adamantane group as a blocking group, and a hydroxylpropyl group as a cyclic molecule in cyclohexanone After dissolution, Duranate TPA-B80E (manufactured by Asahi Kasei Chemical) [block isocyanate], which is a hexamethylene diisocyanate polyisocyanate, is added so that the NCO (reactive group of curing agent) / OH equivalent ratio is 1.05. Adjusted.
The chemical name of the polyrotaxane “Celum Superpolymer SH3400P” is “modified polyrotaxane-graft-polycaprolactone (CAS No. 928045-45-8)”. “Celum superpolymer SH3400P” is polyethylene glycol as a linear molecule, adamantane group as a blocking group, and α-cyclodextrin containing a hydroxyl group as a cyclic molecule.

  Next, a melamine cyanurate dispersion liquid was prepared by dispersing a mixed liquid of melamine cyanurate (STABIACE MC-5F; manufactured by Sakai Chemical Co., Ltd.), which is a nitrogen-based flame retardant, and cyclohexanone for 12 hours with a ball mill. A surface layer coating solution A was prepared by adding 20 parts by weight of melamine cyanurate to 100 parts by weight of polyrotaxane in the above polyrotaxane solution. At this time, the volume average particle diameter of melamine cyanurate was 0.25 μm.

<Production of surface layer>
Next, the surface coating liquid A is continuously applied from the nozzle onto the polyimide base layer while rotating the cylindrical support on which the polyimide base layer A prepared in advance is prepared. It was moved to the axis method of the support while being discharged, and coated in a spiral shape. The coating amount was such that the final surface layer thickness was 100 μm. Thereafter, the cylindrical support coated with the surface layer coating liquid A is rotated as it is and is put into a hot air circulating dryer, heated to 150 ° C. at a temperature rising rate of 3 ° C./min, and heated for 60 minutes. Intermediate transfer belt A was obtained.

(Example 2)
In Example 1, an intermediate transfer belt B was obtained in the same manner as in Example 1 except that the blending amount of melamine cyanurate with respect to 100 parts by weight of the polyrotaxane was changed from 20 parts to 90 parts.

(Example 3)
An intermediate transfer belt C was obtained in the same manner as in Example 1, except that the blending amount of melamine cyanurate with respect to 100 parts by weight of the polyrotaxane was changed from 20 parts to 120 parts.

Example 4
An intermediate transfer belt D was obtained in the same manner as in Example 1 except that melamine cyanurate was changed to melamine sulfate (Apinon-901; manufactured by Sanwa Chemical Co., Ltd.). At this time, the volume average particle diameter of melamine sulfate was 0.3 μm.

(Example 5)
In Example 4, an intermediate transfer belt E was obtained in the same manner as Example 1 except that the dispersion time of melamine sulfate was changed from 12 hours to 2 hours. At this time, the volume average particle diameter of melamine sulfate was 9.3 μm.

(Example 6)
In Example 4, an intermediate transfer belt F was obtained in the same manner as in Example 1 except that the dispersion time of melamine sulfate was changed from 12 hours to 30 minutes. At this time, the volume average particle diameter of melamine sulfate was 14 μm.

(Example 7)
In Example 1, an intermediate transfer belt G was obtained in the same manner as in Example 1 except that the surface layer thickness was changed from 100 μm to 30 μm.

(Example 8)
An intermediate transfer belt H was obtained in the same manner as in Example 1 except that the surface layer thickness was changed from 100 μm to 220 μm in Example 1.

Example 9
An intermediate transfer belt I was obtained in the same manner as in Example 1 except that melamine cyanurate was changed to melamine polyphosphate (MPP-A; manufactured by Sanwa Chemical Co., Ltd.). At this time, the volume average particle diameter of MPP-A was 0.91 μm.

(Example 10)
An intermediate transfer belt J was obtained in the same manner as in Example 1 except that melamine cyanurate was changed to melamine borate (BUDIT 313; manufactured by CBC) in Example 1. At this time, the volume average particle diameter of BUDIT 313 was 1.35 μm.

(Comparative Example 1)
An intermediate transfer belt K was obtained in the same manner as in Example 1 except that no melamine cyanurate was added in Example 1.

(Comparative Example 2)
An intermediate transfer belt L was obtained in the same manner as in Example 1 except that melamine cyanurate was changed to Adeka Stab FP-2100JC (manufactured by ADEKA), which is a phosphorus flame retardant, in Example 1. At this time, the volume average particle diameter of FP-2100JC was 0.24 μm.

(Comparative Example 3)
In Example 1, the intermediate transfer belt M was changed in the same manner as in Example 1 except that the melamine cyanurate was changed to polydibromostyrene (Great Lakes pdbs-80 (manufactured by Chemtura Japan)) which is a halogen flame retardant. Obtained. At this time, the volume average particle size of Great Lakes pdbs-80 was 0.4 μm.

The intermediate transfer belts A to K were mounted on a commercially available image forming apparatus (image MP C7501; manufactured by Ricoh) as shown in FIG. As the paper, rippled paper (manufactured by Ricoh) was used. This paper is a paper with a pattern in Japanese paper style and a smooth surface with a surface quality of 5. The image was a cyan and magenta blue solid image.
Subsequently, the amount of image toner on the intermediate transfer belt before transfer to paper and the amount of toner remaining on the intermediate transfer belt after transfer to paper were measured to calculate the transfer rate. As the output environment, the evaluation was performed in two environments of MM environment (23 ° C., 50% RH) and HH environment (30 ° C., 85% RH).

  Secondary transfer rate (%) = {[toner amount on intermediate transfer belt after transfer (g)] / [toner amount on intermediate transfer belt before transfer (g)]} × 100

  As evaluation criteria, ◎ is a transfer rate of 95% or more, ◯ is 90% or more and less than 95%, Δ is 80% or more and less than 90%, and less than 80% is ×. The series of evaluation results are shown in Table 2 together with the results of the flame-retardant UL94-VTM test (UL94-V test). A flame retardant material having no NOT and a transfer property having no X was regarded as an acceptable level. In any of the examples, image density unevenness and white spots did not occur.

  In Table 2, “VTM-” shall be read as “V-” for those subjected to the UL94-V test.

  As described above, the configuration of the present invention is flexible and excellent in toner releasability, suppresses the occurrence of image density unevenness and white spots, and maintains high transferability even in a high temperature and high humidity environment. An intermediate transfer member that ensures flammability can be provided.

(Reference in FIG. 1)
101 Base layer 102 Surface layer (reference numeral in FIG. 2)
DESCRIPTION OF SYMBOLS 1 Polyrotaxane 2 Linear molecule 3 Cyclic molecule 3A Lipophilic modification group 4 Blocking group (code | symbol of FIG. 3)
P Transfer paper L Laser light 70 Static elimination roller 80 Ground roller 200 Photosensitive drum 201 Photosensitive drum cleaning device 202 Static elimination lamp 203 Charging charger 204 Potential sensor 205 Image density sensor 210 Belt conveying device 230 Revolver developing unit 231Y Y developing machine 231K Bk developing machine 231C C developing machine 231M M developing machine 270 fixing device 271 and 272 fixing roller 500 intermediate transfer unit 501 intermediate transfer belt 502 toner seal member 503 charging charger 504 belt cleaning brush 505 lubricant application brush 506 lubricant 507 primary transfer bias roller 508 Belt drive roller 509 Belt tension roller 510 Secondary transfer counter roller 511 Cleaning counter roller 512 Feedback current detection low La 513 Toner image 514 Optical sensor 600 Secondary transfer unit 601 Transfer paper guide plate 605 Secondary transfer bias roller 606 Transfer paper neutralization charger 608 Cleaning blade 610 Registration roller 801 Primary transfer power source 802 Secondary transfer power source (reference numeral in FIG. 4)
P Transfer paper 10 Printer body 12 Image writing unit 13 Image forming unit 14 Paper feeding unit 15 Fixing device 16 Registration roller 20BK, 20M, 20Y, 20C Developing device 21BK, 21M, 21Y, 21C Photoconductor 22 Intermediate transfer belt 23BK, 23M , 23Y, 23C Primary transfer bias roller 25 Belt cleaning brush 26 Drive roller 27 Lubricant coating device 50 Transfer conveyor belt 60 Secondary transfer bias roller 70 Bias roller

Japanese Patent No. 4810673 JP 2014-066857 A

Claims (10)

An intermediate transfer member having at least a base layer and a surface layer,
The surface layer includes at least a cyclic molecule, a linear molecule that includes the cyclic molecule in a skewered manner, and a blocking group that is disposed at both ends of the linear molecule and prevents the cyclic molecule from being detached. Including a crosslinked polyrotaxane having a flame retardant compound,
An intermediate transfer member, wherein the flame retardant compound is a nitrogen compound.   The intermediate transfer member according to claim 1, wherein the nitrogen-based compound is a melamine salt of an inorganic acid.   The intermediate transfer member according to claim 2, wherein the melamine salt of an inorganic acid is melamine sulfate.   The intermediate transfer member according to any one of claims 1 to 3, wherein a content of the flame retardant compound is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the polyrotaxane.   The intermediate transfer member according to claim 1, wherein the flame retardant compound is a particle having a volume average particle diameter of 10 μm or less.   6. The intermediate transfer member according to claim 1, wherein the thickness of the surface layer is 50 μm or more and 200 μm or less.   The intermediate transfer member according to claim 1, wherein the intermediate transfer member is a seamless belt. An image carrier on which a latent image is formed and capable of carrying a toner image;
Developing means for developing the latent image formed on the image carrier with toner;
An intermediate transfer body on which a toner image developed by the developing means is primarily transferred;
Transfer means for secondary transfer of the toner image carried on the intermediate transfer body to a recording medium,
An image forming apparatus, wherein the intermediate transfer member is the intermediate transfer member according to claim 1.   9. The image forming apparatus according to claim 8, wherein the image forming apparatus is a full-color image forming apparatus, and a plurality of image carriers having developing units for respective colors are arranged in series. A latent image forming step of forming a latent image on the image carrier;
A developing step of developing the latent image formed on the image carrier with toner to form a toner image;
An intermediate transfer step in which the toner image developed in the development step is primarily transferred to an intermediate transfer member;
A transfer step of secondarily transferring the toner image carried on the intermediate transfer member to a recording medium,
An image forming method, wherein the intermediate transfer member is the intermediate transfer member according to claim 1.