JP2021176007A - Electrophotographic belt and electrophotographic image forming device - Google Patents

Abstract

To provide an electrophotographic belt which suppresses bleeding of cation components from an outer surface thereof even after prolonged storage after repetitively outputting images for a long time.SOLUTION: An electrophotographic belt provided herein has a layer containing a thermoplastic resin component containing a heat-melt kneaded product of a thermoplastic polyester resin 502, a cation 501 having a hydroxyl group, an anion, and a compound 503 having at least two amide groups in one molecule.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to an electrophotographic belt and an electrophotographic image forming apparatus provided with the electrophotographic belt.

Patent Document 1 discloses a conductive belt having high conductivity and small fluctuation in electrical resistance even after long-term use. The conductive belt contains a hydrophobic fluorinated sulfoneimide structure or an ionic liquid having hexafluorophosphate as an anion in a thermoplastic resin such as polyester.

Japanese Unexamined Patent Publication No. 2015-23456

According to the study by the present inventors, the electrophotographic belt according to Patent Document 1 is used as an intermediate transfer belt, is used for forming an electrophotographic image for a long period of time, is left for a predetermined period, and then is electrophotographed again. When the image was formed, image defects due to poor transfer of the toner were observed.

One aspect of the present disclosure is to provide an electrophotographic belt that contributes to the stable formation of a high-quality electrophotographic image because the cation component does not easily exude to the surface even after being subjected to image formation for a long period of time and left for a long period of time. It is aimed at. Another aspect of the present disclosure is to provide an electrophotographic image forming apparatus capable of stably forming a high-quality electrophotographic image.

According to one aspect of the present disclosure, a thermoplastic resin composition comprising a thermoplastic polyester resin, a cation having a hydroxyl group, an anion, and a compound having at least two amide groups in one molecule is a hot melt kneaded product. An electrophotographic belt having a layer containing an object is provided.
Further, according to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including the above-mentioned electrophotographic belt as an intermediate transfer belt.

According to one aspect of the present disclosure, it is possible to provide an electrophotographic belt whose surface state of the belt does not easily change from the initial state even after long-term storage after long-term repeated image output. Further, according to another aspect of the present disclosure, it is possible to provide an electrophotographic image forming apparatus capable of stably forming a high-quality electrophotographic image.

It is sectional drawing which shows an example of the full-color electrophotographic image forming apparatus using an electrophotographic process. It is the schematic sectional drawing of the injection molding apparatus used in an Example. It is the schematic sectional drawing of the primary blow molding apparatus used in an Example. It is the schematic sectional drawing of the secondary blow molding apparatus used in an Example. It is explanatory drawing of the effect manifestation mechanism of the electrophotographic belt which concerns on this disclosure. It is explanatory drawing of the structural example of the belt for electrophotographic which concerns on this disclosure.

The present inventor has investigated image defects that occur when the above-mentioned electrophotographic belt according to Patent Document 1 is used as an intermediate transfer belt for forming an electrophotographic image.
Specifically, a portion of the toner-supporting surface of the electrophotographic belt corresponding to the position of the image defect was observed. As a result, untransferred toner and sticky deposits were confirmed. Further elemental analysis of this deposit confirmed that it was a cationic component of the ionic liquid contained in the electrophotographic belt. From this, the present inventor has further bleeded the cation component in the electrophotographic belt conductive with an ionic liquid in order to form a high-quality electrophotographic image more stably. Recognized that it is necessary to develop technology to control the problem.

Here, the reason why the cation component bleeds on the belt surface after the electrophotographic belt according to Patent Document 1 is repeatedly output as an image for a longer period than before and stored for a long period of time is presumed as follows.
That is, the polyester resin contained in the thermoplastic resin composition and the cation and the anion are not completely compatible with each other, and microscopically, the polyester resin phase and the cation and anion phase are mixed. Therefore, cations and anions move toward one surface of the belt and the other toward the other surface (back surface) of the belt according to the direction of voltage application.
In the process of forming an electrophotographic image, there are a primary transfer in which the toner on the photosensitive drum is transferred to an electrophotographic belt and a secondary transfer in which the toner on the electrophotographic belt is transferred to a transfer medium. The direction of application of the voltage applied to the electrophotographic belt is opposite to the thickness direction of the electrophotographic belt in the primary transfer and the secondary transfer, respectively.
Since the amount of energization due to the voltages applied in opposite directions in the primary transfer and the secondary transfer is usually different, the movement of the cation and the anion in the thickness direction tends to be biased in one direction. Therefore, the cations and anions are unevenly distributed in the vicinity of the belt surface by repeatedly outputting the image for a longer period of time than in the conventional case.
When the electrophotographic belt is stored for a long period of time in such a state, a force for the cation component to move toward the outer surface of the electrophotographic belt is exerted in an attempt to alleviate the difference in interfacial energy between the outer surface of the electrophotographic belt and the atmosphere. It acts and the cation component bleeds onto the outer surface of the electrophotographic belt.

The present inventors have conducted repeated studies to suppress the bleeding of such cations. As a result, a heat-melt kneaded product of a thermoplastic polyester resin (hereinafter, also simply referred to as “polyester resin”), a cation having a hydroxyl group, an anion, and a compound having at least two amide groups in one molecule is produced. According to the electrophotographic belt having a layer containing the thermoplastic resin composition containing the cation component, it has been found that the bleeding of the cation component to the outer surface can be better suppressed.
The assumed mechanism by which the exudation of the cation component can be better suppressed by the electrophotographic belt having the above-described configuration will be described with reference to FIG. The cation 501 having a hydroxyl group shown in FIG. 5, polyethylene naphthalate 502 as a polyester resin, and ethylene bisstearic acid amide 503 as a compound having at least two amide groups in one molecule are merely examples. The present disclosure is not limited to these compounds.
The cation 501 having a hydroxyl group and the polyester resin 502 interact with each other by a hydrogen bond or a transesterification reaction between the hydroxyl group 501-1 and the ester bond 502-1 of the polyester resin 502 (see arrow A in FIG. 5). Therefore, it has a high affinity. In addition, the cation 501 having a hydroxyl group and the compound having at least two amide groups in one molecule (hereinafter, may be simply referred to as “amide compound”) 503 are a hydroxyl group 501-1 and an amide group 503. Since it interacts with -1 (see arrow B in FIG. 5), it exhibits high affinity. Further, the amide compound 503 and the polyester resin 502 show high affinity because the amide group 503-1 and the ester bond 502-1 of the polyester resin interact with each other (see arrow C in FIG. 5). .. As described above, it is considered that the amide compound 503 mediates the further improvement of the affinity between the cationic component 501 having a hydroxyl group and the polyester resin 502. In addition, arrows A, B, and C in FIG. 5 schematically show one aspect of the interaction acting between each of the hydroxyl group, the ester bond, and the amide group, and in reality, these functional groups and It is considered that the bonds interact in a complicated manner. Further, in FIG. 5, n, p and q each independently represent an integer of 1 or more, and R ₁ and R ₂ each independently represent a hydrogen atom or an organic group.

Further, as shown in FIG. 5, when the cation has two or more hydroxyl groups, the interaction with the polyester resin and the amide compound is further enhanced, so that the cation bleeds to the outer surface of the electrophotographic belt. , Can be further suppressed.
Further, even when the first layer contains a polyether ester amide (PEEA), since PEEA contains an ester bond and an amide group in the molecule, the mechanism of the electrophotographic belt is similar to the above. Bleed of PEEA to the outer surface can be suppressed. Since PEEA functions as a polymer ion conductive agent, it is a preferable material for further increasing the conductivity of the first layer of the electrophotographic belt.

The electrophotographic belt according to one aspect of the present disclosure is a heat-melt kneaded product containing a thermoplastic polyester resin, a cation having a hydroxyl group, an anion, and a compound having at least two amide groups in one molecule. It has a layer containing a thermoplastic resin composition containing the same. In the present specification, a compound having a cation and a paired aninion may be referred to as an "ionic compound".

<Thermoplastic resin composition>
The thermoplastic resin composition according to the present disclosure is obtained by hot-melting and kneading a component containing a thermoplastic polyester resin, a cation having a hydroxyl group, an anion, and a compound having at least two amide groups in one molecule. Includes heat-melt kneaded products that can be obtained. PEEA may be heat-melted and kneaded together with these components.
The heat-melt kneading means that the resin contained in the thermoplastic resin composition is heated and kneaded in a molten state. At the time of heat melt kneading, the resin having the highest melting point among the resins contained in the thermoplastic resin composition can be kneaded at a temperature equal to or higher than the highest melting point so as to be well kneaded. The kneading method is not particularly limited, and a single-screw extruder, a twin-screw kneading extruder, a Banbury mixer, a roll, a lavender, a plastograph, a kneader, or the like can be used.

<Thermoplastic polyester resin>
The thermoplastic polyester resin can be obtained by polycondensation of a dicarboxylic acid and a diol, polycondensation of an oxycarboxylic acid or a lactone, or polycondensation using a plurality of these components. Further polyfunctional monomers may be used in combination. The thermoplastic polyester resin may be a homopolyester containing one type of ester bond or a copolyester (copolymer) containing a plurality of ester bonds.
As the thermoplastic polyester resin, at least one selected from the group consisting of polyalkylene terephthalate and polyalkylene naphthalate having high crystallinity and exhibiting excellent heat resistance can be mentioned as a preferable example. Further, as the copolyester (copolymer), a copolymer of polyalkylene terephthalate or polyalkylene naphthalate and polyalkylene isophthalate can be preferably used.
The form of the copolymer at this time may be a block copolymer or a random copolymer.
The carbon number of the alkylene in the polyalkylene terephthalate, the polyalkylene naphthalate and the polyalkylene isophthalate is preferably 2 or more and 16 or less from the viewpoint of high crystallinity and heat resistance. More specifically, as the thermoplastic polyester resin, polyethylene terephthalate, polyethylene naphthalate, and a copolymer of polyethylene terephthalate and polyethylene isophthalate are preferable.

The intrinsic viscosity of the thermoplastic polyester resin is preferably 1.4 dl / g or less, more preferably 0.3 dl / g or more and 1.2 dl / g or less. A thermoplastic polyester resin having an intrinsic viscosity of 1.4 dl / g or less has excellent fluidity during heat melt kneading. When the intrinsic viscosity is 0.3 dl / g or more, the strength and durability of the electrophotographic belt can be improved more easily. The intrinsic viscosity of the thermoplastic polyester resin is such that o-chlorophenol is used as a diluting solvent for the thermoplastic polyester resin, the concentration of the o-chlorophenol solution of the thermoplastic polyester resin is 0.5% by mass, and the temperature is 25 ° C. It is a value measured in.

The content of the thermoplastic polyester resin in the thermoplastic resin composition is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, based on the total mass of the thermoplastic resin composition. Is. By setting the content of the thermoplastic polyester resin to 50% by mass or more with respect to the total mass of the thermoplastic resin composition, it is easy to increase the mechanical strength of the thermoplastic resin composition.

<Cation with hydroxyl group>
The cation having a hydroxyl group is not particularly limited, and examples thereof include an ammonium ion, an imidazolium ion, a pyridinium ion, a piperidinium ion, a pyrrolidinium ion, and a phosphonium ion. Among these, ammonium ions and imidazolium ions are preferable from the viewpoint of cost and the like.
Specific examples of the above cations include 2-hydroxyethylammonium ion, 2-hydroxypropylammonium ion, 2-hydroxyethyl-trimethylammonium ion, 2-hydroxypropyl-trimethylammonium ion, and 2-hydroxy-3-methacryloyloxypropyl. Examples thereof include trimethylammonium ion, N-oleyl-N, N-di (2-hydroxyethyl) -N-methylammonium ion, and the like. One type of each of the above cations may be used alone, or two or more types may be used in combination.
The amount of cations contained in the electrophotographic belt, together with the amount of paired anions (as the amount of ionic compounds), is relative to the total amount of the thermoplastic resin composition in terms of the electrical resistance of the electrophotographic belt. It is preferable that the content is 0.5% by mass or more. The upper limit is not particularly limited, but even if it is added in an amount exceeding 8% by mass, the effect of reducing the electric resistance is limited. Further, from the viewpoint of good moldability of the thermoplastic resin composition, it is preferably 8% by mass or less. Further, the compounding to the thermoplastic resin composition can also be compounded as an ionic compound.

<Anion>
The anion, form the cation and a counter is not particularly limited as long as it can form an ionic ^{_{compound, ClO 4 -, Br -,}} Cl -, AlCl 4 -, Al 2 Cl 7 -, NO 3 -, BF ^{_{4 -, PF 6 -, CH}} 3 COO -, CF 3 COO -, CF 3 SO 3 -, (CF 3 SO 2) 3 C -, AsF 6 -, SbF 6 -, F (HF) n -, CH 3 CH ₂ OSO ₃ ⁻ , H ₂ PO ₄ ⁻ , CF ₃ CF ₂ CF ₂ CF ₂ SO ₃ ⁻ , CF ₃ CF ₂ CF ₂ COO ⁻ , and anions represented by the following structural formula (1) can be mentioned. Among these, sulfoneimide-based anions represented by the following structural formula (1) are preferable from the viewpoint of affinity with polyester resin, conductivity and the like.

Specific examples of the anion satisfying the structural formula (1) include bis (trifluoromethanesulfonyl) imide ion, bis (perfluoroethanesulfonyl) imide ion, bis (perfluoropropanesulfonyl) imide ion, and bis (nonafluorobutanesulfonyl) imide ion ( Bis (perfluorobutanesulfonyl) imide ion), trifluoromethanesulfonyl perfluoropropanesulfonylimide ion, trifluoromethanesulfonyl perfluorobutanesulfonylimide ion and the like. One type of each of the above anions may be used alone, or two or more types may be used in combination.

<Compound having at least two amide groups in one molecule (amide compound)>
A compound having at least two amide groups in one molecule preferably has a molecular weight of 1000 or less, particularly 800 or less. The lower limit of the molecular weight of the amide compound is not particularly limited, but is preferably 200 or more. When the molecular weight of the amide compound is within the above range, it is considered that the thermoplastic polyester, the ionic liquid, and the amide compound can interact more efficiently during thermal melt kneading.
Further, the amide compound is preferably melted at the temperature at the time of heat melting and kneading. Its melting point is preferably 70 ° C. or higher and lower than 200 ° C., and more preferably 100 ° C. or higher and 170 ° C. or lower. When the melting point is within the above range, the dispersibility and dispersibility in the thermoplastic resin composition are excellent at the time of thermal melt kneading, the polyester resin is easily arranged between the molecules of the cation and the anion, and the decomposition due to thermal deterioration also occurs. It is unlikely to occur. Therefore, it is easy to further enhance the bleeding suppressing effect.
As the compound having at least two amide groups, fatty acid bisamide is preferable. The fatty acid bisamide contains a fatty acid group (preferably a long-chain fatty acid group) and an amide group in the molecule, has excellent compatibility with a thermoplastic polyester resin, and is relatively stable thermally and chemically.
From the viewpoint of compatibility with the thermoplastic polyester resin and thermal and chemical stability, the long-chain fatty acid group preferably has a carbon number range of 7 to 23. Further, as a compound having at least two amide groups, an aromatic bisamide containing a fatty acid group and an amide group in the molecule and having the amide groups bonded with an aromatic hydrocarbon can also be used.

As the fatty acid bisamide, for example, alkylene fatty acid bisamides such as ethylene bis fatty acid amide can be used. Specific examples thereof include methylene bisstearic acid amide (Tm (melting point): 142 ° C.), ethylene biscapric acid amide (Tm: 161 ° C.), ethylene bislauric acid amide (Tm: 157 ° C.), and ethylene bisstearic acid amide (Tm: 157 ° C.). Tm: 145 ° C), ethylene bishydroxystearic acid amide (Tm: 145 ° C), ethylene bisbechenic acid amide (Tm: 142 ° C), hexamethylene bisstearic acid amide (Tm: 140 ° C), hexamethylene bisbechenic acid amide. (Tm: 142 ° C.), Hexamethylenebishydroxystearic acid amide (Tm: 135 ° C.), N, N'-distearyl adipate amide (Tm: 141 ° C.), N, N'-distearyl sebacic acid amide (Tm: Tm) 136 ° C.), ethylene bisoleic acid amide (Tm: 115 ° C.), ethylene biserucate amide (Tm: 120 ° C.), hexamethylene bisoleic acid amide (Tm: 110 ° C.), N, N'-diorail adipine Examples thereof include acid amide (Tm: 118 ° C.) and N, N'-diorail sebacic acid amide (Tm: 113 ° C.).

The content (mass) of the compound having at least two amide groups in one molecule is preferably 2% or more and 80% or less with respect to the total amount of the cations and anions (mass of the ionic compound). More preferably, it is 5% or more and 50% or less.
When the content is 2% or more, the number of amide groups interacting with the thermoplastic polyester resin and the cations and anions is large, which is preferable for further suppressing bleeding. Further, when it is 80% or less, it becomes easy to suppress a decrease in the melt viscosity of the thermoplastic resin composition and suppress a decrease in the strength of the electrophotographic belt. In addition, it is easy to suppress an excessive decrease in the mobility of the cations and anions and to suppress an increase in resistance of the electrophotographic belt.

<Polyester ester amide (PEEA)>
Examples of PEEA include compounds having a copolymer mainly composed of a polyamide block unit such as nylon 6, nylon 66, nylon 11, and nylon 12 and a polyether ester unit.
For example, a polymer derived from a salt of lactam (for example, caprolactam, lauryl lactam) or aminocarboxylic acid, polyethylene glycol, and a dicarboxylic acid can be mentioned. Specific examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid and the like. PEEA can be produced by a known polymerization method such as melt polymerization. Of course, PEEA is not limited to these. Further, PEEA may be a blend or alloy of two or more kinds. The compound having at least two amide groups in one molecule used in the present disclosure is mainly a low molecular weight compound having a molecular weight of 1000 or less, while PEEA is a high molecular weight compound having a larger molecular weight.

<Additives>
Other components may be added to the thermoplastic resin composition as long as the effects of the present disclosure are not impaired. Examples of other components include conductive polymer compounds, antioxidants, UV absorbers, organic pigments, inorganic pigments, pH regulators, cross-linking agents, compatibilizers, mold release agents, cross-linking agents, coupling agents, etc. Includes lubricants, insulating fillers, conductive fillers and the like. One type of these additives may be used alone, or two or more types may be used in combination. The amount of the additive used can be appropriately set and is not particularly limited.

<Belt for electrophotographic>
FIG. 6A shows a perspective view of an electrophotographic belt 500 having an endless belt shape according to one aspect of the present disclosure. As an example of the layer structure, the cross section of the line AA'in FIG. 6 (a) is composed of only the first layer 501 containing the thermoplastic resin composition as shown in FIG. 6 (b-1). A single layer (monolayer) structure can be mentioned. In this case, the outer surface 500-1 of the first layer becomes the toner-supporting surface (outer surface) of the electrophotographic belt.
As another example of the layer structure, as shown in FIG. 6 (b-2), the cross section of the AA'line covers the first layer 501 and the outer peripheral surface of the first layer 501. An example has a laminated structure having two layers 502. When the second layer 502 is provided, the outer surface 500-1 of the second layer 502 serves as the toner supporting surface of the electrophotographic belt.
Examples of the second layer include a layer having excellent wear resistance, which contains a cured product of an active energy ray-curable resin. Such a second layer can be provided, for example, by applying a composition containing an active energy ray-curable resin such as a photocurable resin on the outer peripheral surface of the first layer and curing the composition. ..
The effect of the present disclosure in the electrophotographic belt having such a laminated structure is that the first layer and the first layer are prevented from seeping out the cation component at the interface between the first layer and the second layer. Suppression of a decrease in adhesion to the second layer can be mentioned.
Further, a third layer (not shown) may be provided to cover the inner peripheral surface of the first layer. Examples of the third layer include a resin layer for reinforcing the first layer and a conductive layer for making the inner peripheral surface of the electrophotographic belt conductive.

The first layer having an endless belt shape can be produced, for example, by the following method.
i) A method of melt-extruding a mixture of a thermoplastic polyester resin, an ionic conductive agent having a sulfonimide structure as an anion, and a compound having at least two amide groups in one molecule into a cylindrical shape ii) The thermoplastic resin composition. A method of molding pellets into an endless belt shape using a molding method such as injection molding, stretch blow molding, or inflation molding.
Among them, examples of the method i) include an internal cooling mandrel method of a downward extrusion method capable of controlling the inner diameter of an extruded tube with high accuracy, and a vacuum sizing method.

The method for manufacturing an electrophotographic belt by stretch blow molding in ii) includes the following steps. That is, a step of molding a preform of the thermoplastic resin composition. The step of heating the preform. A step of mounting the heated preform on a mold for endless belt molding, and then inflowing gas into the mold to perform stretch blow molding. A step of cutting a stretched molded product obtained by the stretch blow molding to obtain an endless shaped belt.
The thickness of the first layer is preferably 40 μm or more and 500 μm or less, and particularly preferably 50 μm or more and 100 μm or less.
In order to improve the appearance of the surface of the electrophotographic belt and improve the releasability of toner and the like, a treatment agent may be applied to the surface of the thermoplastic resin composition layer, or a surface treatment such as polishing treatment may be applied. May be good. Further, the outermost layer may be provided on the surface of the thermoplastic resin composition layer by sputtering or the like.
The use of the electrophotographic belt is not particularly limited, but is preferably used for, for example, an intermediate transfer belt that temporarily transfers and holds a toner image, a transfer transfer belt that conveys a recording material as a transfer material, and the like. .. In particular, it can be suitably used as an intermediate transfer belt. When the electrophotographic belt is used as an intermediate transfer belt, the surface resistivity of the electrophotographic belt is preferably 1 × 10 ³ Ω / □ or more and 1 × 10 ¹² Ω / □ or less. When the surface resistivity is 1 × 10 ³ Ω / □ or more, it is possible to prevent the resistance from becoming low, easily obtain a transfer electric field, and effectively prevent image omission and roughness. Can be done. When the surface resistivity is 1 × 10 ¹² Ω / □ or less, it is possible to more effectively suppress the increase in the transfer voltage, and it is possible to effectively suppress the increase in size and cost of the power supply.

<Electrophotograph image forming apparatus>
Hereinafter, an example of an electrophotographic image forming apparatus using the electrophotographic belt according to one aspect of the present disclosure as an intermediate transfer belt will be described. As shown in FIG. 1, this electrophotographic image forming apparatus has a so-called tandem type configuration in which electrophotographic stations of a plurality of colors are arranged side by side in the rotation direction of the intermediate transfer belt. In the following description, the codes of the configurations for each color of yellow, magenta, cyan, and black are subscripted with Y, M, C, and k, respectively, but the subscripts are omitted for the same configuration. In some cases.

In FIG. 1, around the photosensitive drums (photoreceptors, image carriers) 1Y, 1M, 1C, 1k, charging devices 2Y, 2M, 2C, 2k, exposure devices 3Y, 3M, 3C, 3k, developing devices 4Y, 4M, 4C, 4k, and an intermediate transfer belt (intermediate transfer body) 6 are arranged. The photosensitive drum 1 is rotationally driven at a predetermined peripheral speed (process speed) in the direction of arrow F. The charging device 2 charges the peripheral surface of the photosensitive drum 1 to a predetermined polarity and potential (primary charging). The laser beam scanner as the exposure apparatus 3 outputs laser light that has been on / off-modulated in response to image information input from an external device such as an image scanner (not shown) or a computer, and charges the photosensitive drum 1. The surface is scanned and exposed. By this scanning exposure, an electrostatic latent image corresponding to the target image information is formed on one surface of the photosensitive drum.
The developing devices 4Y, 4M, 4C, and 4k contain toners of each color component of yellow (Y), magenta (M), cyan (C), and black (k), respectively. Then, the developing device 4 to be used is selected based on the image information, the developing agent (toner) is developed on one surface of the photosensitive drum, and the electrostatic latent image is visualized as a toner image. In the present embodiment, a reverse development method is used in which toner is adhered to the exposed portion of the electrostatic latent image to develop the image. Further, such a charging device, an exposure device, and a developing device constitute an electrophotographic image forming means.

Further, the intermediate transfer belt 6 is composed of an electrophotographic belt having an endless shape. The intermediate transfer belt 6 is stretched by a plurality of rollers 20, 21 and 22 so that the outer peripheral surface of the intermediate transfer belt 6 comes into contact with the surface of the photosensitive drum 1. In the present embodiment, the roller 20 is a tension roller for controlling the tension of the intermediate transfer belt 6 to be constant, the roller 22 is a drive roller for the intermediate transfer belt 6, and the roller 21 is an opposing roller for secondary transfer. Then, the intermediate transfer belt 6 is rotated in the direction of the arrow G by the drive of the roller 22. Further, primary transfer rollers 5Y, 5M, 5C, and 5k are arranged at the primary transfer positions facing the photosensitive drum 1 with the intermediate transfer belt 6 interposed therebetween.
The unfixed toner images of each color formed on the photosensitive drum 1 are obtained by applying a primary transfer bias having a polarity opposite to the charging polarity of the toner to the primary transfer roller 5 by a constant voltage source or a constant current source (not shown). The primary transfer is sequentially electrostatically performed on the intermediate transfer belt 6. Then, a full-color image in which four colors of unfixed toner images are superimposed on the intermediate transfer belt 6 is obtained. The intermediate transfer belt 6 rotates while carrying the toner image transferred from the photosensitive drum 1 in this way. After each rotation of the photosensitive drum 1 after the primary transfer, the surface of the photosensitive drum 1 is cleaned with the transfer residual toner by the cleaning device 11, and the image-forming process is repeated.

Further, at the secondary transfer position of the intermediate transfer belt 6 facing the transfer path of the recording material 7 as the transfer medium, the secondary transfer roller (transfer portion) 9 is pressure-welded on the toner image-carrying surface side of the intermediate transfer belt 6. doing. Further, on the back surface side of the intermediate transfer belt 6 at the secondary transfer position, an opposing roller 21 that serves as an opposing electrode of the secondary transfer roller 9 and to which a bias is applied is arranged. When the toner image on the intermediate transfer belt 6 is transferred to the recording material 7, a bias having the same polarity as the toner is applied to the opposing roller 21 by the transfer bias applying means 28, for example, −1000 to −3000V, and −10 to − A current of 50 μA flows. The transfer voltage at this time is detected by the transfer voltage detecting means 29. Further, a cleaning device (belt cleaner) 12 for removing the toner remaining on the intermediate transfer belt 6 after the secondary transfer is provided on the downstream side of the secondary transfer position.
The recording material 7 passes through the transport guide 8 and is transported in the direction of arrow H, and is introduced at the secondary transfer position. The recording material 7 introduced at the secondary transfer position was held and conveyed at the secondary transfer position, and at that time, it was controlled to a predetermined value by the secondary transfer bias applying means 28 to the opposing roller 21 of the secondary transfer roller 9. A constant voltage bias (transfer bias) is applied. By applying a transfer bias having the same polarity as the toner to the opposing roller 21, a four-color full-color image (toner image) superimposed on the intermediate transfer belt 6 at the transfer site is collectively transferred to the recording material 7 and transferred onto the recording material. Form a full-color unfixed toner image. The recording material 7 to which the toner image has been transferred is introduced into a fuser (not shown) and heat-fixed.

Hereinafter, examples and comparative examples will be shown, and the electrophotographic belt and the electrophotographic image forming apparatus according to the present disclosure will be specifically described. The electrophotographic belt and the electrophotographic image forming apparatus according to the present disclosure are not limited to the configurations embodied in the examples.
First, Tables 1 to 5 below show materials (thermoplastic polyester resin, ionic compounds having cations and anions, amide compounds, polyether ester amides, silicone particles) used for producing the electrophotographic belts according to Examples and Comparative Examples. The materials described in 1 were prepared.
The cations in the ionic compounds 1 to 6 shown in Table 2 correspond to the cations having a hydroxyl group, while the cations in the ionic compound 7 do not correspond to the cations having the hydroxyl group. Further, the amide compounds 1 and 2 shown in Table 3 correspond to compounds having at least two amide groups in one molecule, while the amide compound 3 does not correspond to this compound.

Characteristic value measurement method, evaluation method)
The evaluation methods (1) to (4) of the electrophotographic belt according to the examples and the comparative examples will be described below. In the following evaluation, the transfer medium used for image formation was left in an environment with a temperature of 23 ° C. and a relative humidity of 45% for one day, with Ra (arithmetic mean roughness) of 4, Rzjis (ten-point average roughness). A4 size paper with a value of 15 was used.

(1) Surface resistivity value The surface resistivity of the electrophotographic belt was measured based on the method specified in Japanese Industrial Standards (JIS) -K6911 1995. As a measuring device, a probe (trade name: Hiresta UP MCP-HT450 type) with an inner diameter of 50 mm for the main electrode, an inner diameter of 53.2 mm for a guard ring electrode, and an outer diameter of 57.2 mm for a high resistance meter (trade name: Hiresta UP MCP-HT450 type). UR-100) was used. The high resistance tester and probe are manufactured by Mitsubishi Chemical Analytech.
The produced electrophotographic belt was left in an environmental test room controlled at a temperature of 23 ° C. and a relative humidity of 50% for 12 hours. Then, under an environment of a temperature of 23 ° C. and a relative humidity of 50%, a voltage of 250 V was applied to the electrophotographic belt to be measured for 10 seconds, and the surface resistivity at four points in the circumferential direction of the electrophotographic belt was measured. The logarithm of the average value (ρs) of the obtained surface resistivity based on 10 was defined as logρs and used as an index of electrical resistance. The values shown in the “Surface specific resistance value” column of Tables 6 to 8 are the values of this logρs.

(2) Initial Toner Transfer Efficiency The produced electrophotographic belt was attached to a drum cartridge of a full-color electrophotographic apparatus (trade name: LBP-5200, manufactured by Canon Inc.) as an intermediate transfer belt. Using this full-color electrophotographic apparatus, cyan toner and magenta toner were superposed on the transfer medium to form a solid purple image.
The toner transfer efficiency is the amount of toner F (g) held on the surface of the electrophotographic belt by the primary transfer from the photosensitive drum, and the residual toner remaining on the surface of the electrophotographic belt when the toner is secondarily transferred to the transfer medium. It was calculated from the amount S (g). Specifically, it is represented by the following formula [1].
Toner transfer efficiency (%) = (1-S / F) x 100 [1]

(3) Toner transfer efficiency after durability test The toner transfer efficiency of the image formed on the 300,000th transfer medium was measured by the same method as in (2) above.

(4) Toner transfer efficiency of the electrophotographic belt left for 10 days after the durability test The electrophotographic belt whose durability test was performed in (3) above is controlled to a temperature of 23 ° C. and a relative humidity of 50% in a full-color electrophotographic apparatus. After storing for 10 days in this state, cyan toner and magenta toner were superposed on the transfer medium to form a solid purple image. For the image formed on the transfer medium, the toner transfer efficiency was measured by the same method as in (2) above.

[Examples 1 to 10]
After pre-blending the materials according to the formulations shown in Table 6, the thermoplastic resin composition in the form of pellets is heat-melted and kneaded using a twin-screw extruder (trade name: TEX44α, manufactured by Japan Steel Works, Ltd.). Was prepared. The hot melt kneading temperature was adjusted to be within the range of 270 ° C. or higher and 300 ° C. or lower, and the hot melt kneading time was set to about 3 minutes.
The obtained pellet-shaped thermoplastic resin composition was dried at a temperature of 140 ° C. for 6 hours. Next, a dried pellet-shaped thermoplastic resin composition was put into a hopper 48 of an injection molding apparatus (trade name: SE180D, manufactured by Sumitomo Heavy Industries, Ltd.) having the configuration shown in FIG.
Then, the cylinder set temperature was set to 290 ° C., the mixture was melted in the screws 42 and 42A, and injection molded into a mold (not shown) through the nozzle 41A to prepare a preform 104 (see FIG. 3). The injection molding mold temperature at this time was 30 ° C.

Next, the preform 104 was placed in the heating device 107 at a temperature of 500 ° C. of the primary blow molding apparatus shown in FIG. 3 to be softened, and the preform 104 was heated at 500 ° C. Then, in the blow mold 108 in which the mold temperature is maintained at room temperature, the preform temperature is 160 ° C., the air pressure is 0.3 MPa, and the stretching rod speed is 1000 mm / s by the force of the stretching rod 109 and the air (blow air injection portion 110). Blow molding was performed to obtain a blow bottle 112.

Next, the obtained blow bottle 205 was set in the nickel cylindrical mold 201 manufactured by electroforming of the secondary blow molding apparatus shown in FIG. 4, and the outer mold 203 was mounted. By applying an air pressure of 0.1 MPa into the blow bottle 205 and adjusting so that air does not leak to the outside, the blow bottle 205 is transferred to the inner surface of the mold, and the nickel cylindrical mold 201 is rotated to the heating heater 202. The mixture was uniformly heated at 190 ° C. for a total of 60 seconds.
Then, air was blown onto the nickel cylindrical mold to cool it to room temperature, the pressure applied to the inside of the blow bottle was released, and a blow bottle having improved dimensions was obtained by annealing. An endless belt was obtained by cutting both ends of this blow bottle. This endless belt was used as it was as an electrophotographic belt. The thickness of the electrophotographic belt was 70 μm. Table 6 shows the results of the evaluations (1) to (4) above for this electrophotographic belt.

[Examples 11 to 15]
An endless belt was obtained in the same manner as in Example 1 except that the formulations shown in Table 7 were used. With this endless belt as the base layer, it is made of acrylic resin, which is an active energy ray-curable resin, for the purpose of improving adhesion to other contact members such as photosensitive drums and cleaning blades, and toner releasability. The outer layer was provided as follows.

The following materials were mixed as raw materials for the outermost layer of the acrylic resin.
100 parts by mass of dipentaerythritol hexaacrylate (trade name: light acrylate DPE-6A, manufactured by Kyoeisha Chemical Co., Ltd.)
・ Carbon black (Ketchen black) 15 parts by mass (Product name: MHI Black # 273, manufactured by Mikuni Color Co., Ltd.)
-Photopolymerization initiator 5 parts by mass (trade name: Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.).

Then, this mixture was diluted with methyl ethyl ketone so that the resin solid content concentration became 6% by mass, and stirred with a stirrer to obtain a uniform mixture for forming the outermost layer of the acrylic resin. This mixed solution was uniformly applied to the outer peripheral surface of the base layer by a spray method, dried at 60 ° C. for 1 minute to remove the solvent, and then irradiated with ultraviolet rays to cure. In this way, an electrophotographic belt having an outermost layer of an acrylic resin having a thickness of 2 μm formed on the outer peripheral surface of the base layer was obtained. As an ultraviolet source, an ultraviolet irradiation device (trade name: UE06 / 81-3, manufactured by Eye Graphics Co., Ltd.) is used ^{to irradiate ultraviolet rays until the integrated light amount reaches 1000 mJ / cm 2,} and the outermost layer of the acrylic resin is irradiated with ultraviolet rays. UV curing was performed. Table 7 shows the results of the evaluations (1) to (4) above for the obtained electrophotographic belt.

As shown in Tables 6 and 7, in each of the material compositions of Examples 1 to 15, in the toner transfer efficiency evaluation of the electrophotographic belt, the toner transfer efficiency after being left for 10 days after the durability test was all 92%. The above was very good.

[Comparative Examples 1 to 7]
An electrophotographic belt was produced in the same manner as in Example 1 or Example 11 except that the material types and blending amounts were as shown in Table 8 below. The results of these evaluations are shown in Table 8.

In Comparative Examples 1, 2 and 3, a hydroxyl group-free cation (ionic compound 7) is contained. In Comparative Examples 1 and 4, the amide compound is not contained. In Comparative Examples 5, 6 and 7, a compound having one amide group is contained instead of the compound having at least two amide groups in one molecule. Further, in Comparative Example 7, the outermost layer made of acrylic resin was provided.
In each of the comparative examples, the toner transfer efficiency after being left for 10 days after the durability test was 10% or more lower than that after the initial and durability tests. From this result, the affinity due to the interaction between the thermoplastic polyester resin and the cation is not improved except for the combination of the cation specified in the present disclosure and the compound having an amide group, and the adhesion of bleeding substances on the belt surface is suppressed. It was verified that the effect was not obtained.

1 Photosensitive drum 2 Charging device 3 Exposure device 4 Developing device 5 Primary transfer roller 6 Intermediate transfer belt 7 Recording material 9 Secondary transfer roller 11 Cleaning device 12 Cleaning device (belt cleaner)
20 Tension roller 21 Opposing roller 22 Drive roller 28 Transfer bias applying means 29 Transfer high voltage detecting means

Claims (18)

A first layer containing a thermoplastic resin composition containing a heat-melt kneaded product of a thermoplastic polyester resin, a cation having a hydroxyl group, an anion, and an amide compound having at least two amide groups in one molecule. An electrophotographic belt characterized by having. The electrophotographic belt according to claim 1, wherein the amide compound has a molecular weight of 1000 or less. The electrophotographic belt according to claim 1 or 2, wherein the cation has two or more hydroxyl groups in one molecule. Any one of claims 1 to 3, wherein the cation is at least one cation selected from the group consisting of ammonium ion, imidazolium ion, pyridinium ion, piperidinium ion, pyrrolidinium ion and phosphonium ion. The electrophotographic belt described in the section. The electrophotographic belt according to any one of claims 1 to 4, wherein the anion has a structure represented by the following structural formula (1).

The electrophotographic belt according to any one of claims 1 to 5, wherein the thermoplastic polyester resin contains at least one selected from polyalkylene terephthalate and polyalkylene naphthalate. The electrophotographic belt according to claim 6, wherein the polyalkylene terephthalate is polyethylene terephthalate. The electrophotographic belt according to claim 6, wherein the polyalkylene naphthalate is polyethylene naphthalate. The electrophotographic belt according to any one of claims 1 to 8, wherein the amide compound is a fatty acid bisamide. The electrophotographic belt according to claim 9, wherein the fatty acid bisamide is an ethylene bis fatty acid amide. The electrophotographic belt according to claim 10, wherein the ethylene bis fatty acid amide is ethylene bisstearic acid amide or ethylene biscapric acid amide. The electron according to any one of claims 1 to 11, wherein the amount of the ionic compound having a cation and an anion is 0.5% by mass or more and 8% by mass or less with respect to the total amount of the thermoplastic resin composition. Photo belt. Any one of claims 1 to 12, wherein the mass of the compound having at least two amide groups in one molecule is 2% or more and 80% or less with respect to the mass of the ionic compound having cations and anions. The electrophotographic belt described in. The electrophotographic belt according to any one of claims 1 to 13, wherein the thermoplastic resin composition further contains a polyether ester amide. The electrophotographic belt according to any one of claims 1 to 14, further comprising a second layer containing a cured product of a composition containing an active energy ray-curable resin. The electrophotographic belt according to any one of claims 1 to 15, wherein the electrophotographic belt has an endless belt shape. The electrophotographic belt has an endless shape and further has a second layer covering the outer peripheral surface of the first layer.
The electrophotographic belt according to any one of claims 1 to 14, wherein the second layer contains a cured product of a composition containing an active energy ray-curable resin. An electrophotographic image forming apparatus provided with an intermediate transfer belt.
An electrophotographic image forming apparatus, wherein the intermediate transfer belt is composed of the electrophotographic belt according to any one of claims 1 to 17.

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