JP2022167788A - Electrophotographic belt and electrophotographic image formation device - Google Patents

Abstract

To provide a high-quality electrophotographic belt.SOLUTION: The electrophotographic belt includes at least a base layer and a surface layer, and the surface layer includes A, B, and C as described below: A denotes a compound 1 having a structure shown by the following structural formula (I) and the structural formula (II); B denotes perfluoropolyether; and C denotes a binding resin.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to an electrophotographic belt used in electrophotographic image forming apparatuses such as copiers and printers, and an electrophotographic image forming apparatus equipped with the electrophotographic belt.

In electrophotographic image forming apparatuses capable of forming full-color images, a tandem method is widely used to obtain a full-color image by superimposing YMCK toner images on an intermediate transfer belt and then transferring them all at once onto paper. It is Y represents yellow, M represents magenta, C represents cyan, and K represents black. As an intermediate transfer belt used here, for example, an electrophotographic belt having a base layer in which carbon black is dispersed in a binder resin such as polyimide or polyetheretherketone is known.

Along with the demand for higher image quality of electrophotographic images, the intermediate transfer belt is required to further improve the secondary transfer characteristics of the toner. In order to improve the secondary transfer property of the intermediate transfer belt, perfluoropolyether is contained in the surface layer constituting the toner carrying surface of the intermediate transfer belt (hereinafter also simply referred to as the "surface"). It has been proposed to improve toner releasability. and,
Patent Document 1 discloses an electrophotographic belt having a surface layer in which perfluoropolyether is dispersed in a binder resin as a comb-shaped graft copolymer. The comb-shaped graft copolymer is a copolymer of a (meth)acrylate having a specific molecular weight and a fluoroalkyl group and a methacrylate macromonomer having polymethyl methacrylate as a side chain. It is disclosed that the perfluoropolyether can be better dispersed in the binder resin by using such a comb-shaped graft copolymer.

JP 2019-12265 A

According to the studies of the present inventors, the comb-shaped graft copolymer according to Patent Document 1 was excellent in perfluoropolyether dispersibility. Here, the present inventors investigated setting the number of continuous carbon atoms to which fluorine atoms are bonded in the comb-shaped graft copolymer to be 3 or less. Specifically, they introduced an oxygen atom into the carbon chain constituting the main chain of the perfluoroalkyl group, and examined setting the number of consecutive carbon atoms bonded to fluorine atoms to 3 or less. It is believed that organofluorine compounds in which the number of consecutive carbon atoms to which fluorine atoms are bonded is 3 or less are excellent in decomposability in the natural environment and hardly remain in the environment. Accordingly, the present inventors have investigated an electrophotographic belt having a surface layer in which perfluoropolyether is dispersed in a binder resin using the comb-shaped graft copolymer which is considered to be environmentally friendly. . As a result, the cleanability of the surface of the electrophotographic belt may deteriorate over time.
One aspect of the present disclosure is directed to providing an electrophotographic belt that is environmentally friendly and that can maintain good surface cleanability over a long period of time. Another aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images.

According to one aspect of the present disclosure, there is provided an electrophotographic belt having at least a base layer and a surface layer, the surface layer containing A, B, and C below:
A: Compound 1 having a structure represented by the following chemical structural formula (I) and a structure represented by the following chemical structural formula (II)
B: Perfluoropolyether C: Binder resin

According to another aspect of the present disclosure, an image carrier that carries a toner image; and a transfer belt, wherein the intermediate transfer belt is the electrophotographic belt described above.

According to one aspect of the present disclosure, it is possible to obtain an electrophotographic belt that is excellent in environmental adaptability and capable of forming good electrophotographic images over a long period of time. Further, according to one aspect of the present disclosure, it is possible to obtain an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present disclosure; FIG. 1 is a cross-sectional view showing the configuration of an intermediate transfer belt according to an embodiment of the present disclosure; FIG.

The surface of an electrophotographic belt having a surface layer in which a perfluoropolyether is dispersed in a binder resin using the comb-shaped graft copolymer which is considered to be friendly to the environment has good cleanability. The reason for the decrease over time is considered as follows. That is, it is considered that the comb-shaped graft copolymer in which the number of consecutive carbon atoms to which fluorine atoms are bonded is 3 or less has a low perfluoropolyether dispersibility. Therefore, it becomes difficult to finely disperse the perfluoropolyether in the binder resin. As a result, the surface layer has large domains of perfluoropolyether. Such a surface layer has a low hardness and is scraped off by repeated cleaning of the surface with a cleaning blade. At the same time, the perfluoropolyether is also lost from the surface layer, and it is considered that the toner releasability of the surface is lowered.
Based on these considerations, further studies were conducted. As a result, the compound having the structure represented by the above chemical structural formula (I) and the structure represented by the following chemical structural formula (II) has an environmentally friendly structure, and is a dispersion of the perfluoropolyether in the binder resin. I found that I was also good at Noh.
Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. However, the specific aspects described in the following embodiments, such as the dimensions, materials, shapes, and relative arrangement of components, may be changed as appropriate depending on the configuration of the device to which the present disclosure is applied and various conditions. and the scope of the present disclosure is not limited to only those specific aspects.

[Image forming apparatus]
An electrophotographic image forming apparatus 100 shown in FIG. 1 is a schematic cross-sectional view of an electrophotographic image forming apparatus equipped with an electrophotographic belt according to one embodiment of the present invention.
In this electrophotographic image forming apparatus, yellow (Y), magenta (M), cyan (C), and black (K) are sequentially applied along the flat portion of an intermediate transfer belt 7, which is an intermediate transfer member, in the moving direction. Image forming units Py, Pm, Pc, and Pk for each color are arranged. Here, 1Y, 1M, 1C, and 1K denote electrophotographic photosensitive members, respectively, and 2Y, 2M, 2C, and 2K denote charging rollers, respectively. 3Y, 3M, 3C, and 3K denote laser exposure devices, 4Y, 4M, 4C, and 4K denote developing devices, and 5Y, 5M, 5C, and 5K denote primary transfer rollers, respectively. Since the image forming units have the same basic configuration, only the yellow image forming unit Py will be described in detail.

The yellow image forming unit Py has a drum-type electrophotographic photosensitive member (hereinafter also referred to as “photosensitive drum” or “first image carrier”) 1Y as an image carrier. The photosensitive drum 1Y is formed by laminating a charge generation layer, a charge transport layer and a surface protection layer in order on an aluminum cylinder as a base.
Also, the yellow image forming unit Py is provided with a charging roller 2Y as charging means. By applying a charging bias to the charging roller 2Y, the surface of the photosensitive drum 1Y is uniformly charged.
A laser exposure device 3Y as image exposure means is arranged above the photosensitive drum 1Y. The laser exposure device 3Y scans and exposes the uniformly charged surface of the photosensitive drum 1Y according to image information to form an electrostatic latent image of the yellow color component on the surface of the photosensitive drum 1Y.

The electrostatic latent image formed on the photosensitive drum 1Y is developed with toner, which is a developer, by a developing device 4Y as developing means. The developing device 4Y includes a developing roller 4Ya as a developer bearing member and a regulating blade 4Yb as a developer amount regulating member, and contains yellow toner as developer. The developing roller 4Ya supplied with yellow toner is in light pressure contact with the photosensitive drum 1Y in the developing section, and is rotated in the forward direction with a speed difference from the photosensitive drum 1Y. The yellow toner conveyed to the developing section by the developing roller 4Ya adheres to the electrostatic latent image formed on the photosensitive drum 1Y by applying a developing bias to the developing roller 4Ya.
Thereby, a visible image (yellow toner image) is formed on the photosensitive drum 1Y.

The intermediate transfer belt 7 is stretched around a drive roller 71, a tension roller 72, and a driven roller 73, and is moved (rotated) in the direction indicated by the arrow in the figure while coming into contact with the photosensitive drum 1Y.
The yellow toner image formed on the photosensitive drum (on the first image bearing member) that has reached the primary transfer portion Ty is transferred to the primary transfer portion that is arranged to face the photosensitive drum 1Y with the intermediate transfer belt 7 interposed therebetween. It is primarily transferred onto the intermediate transfer belt 7 by the body (primary transfer roller 5Y).

Similarly, the image forming operation described above is performed in each of the magenta (M), cyan (C), and black (K) units Pm, Pc, and Pk as the intermediate transfer belt 7 moves. Four color toner images of yellow, magenta, cyan, and black are laminated. The laminated four-color toner image is conveyed along with the movement of the intermediate transfer belt 7, and in the secondary transfer portion T', a transfer material is conveyed at a predetermined timing by a secondary transfer roller 8 as a secondary transfer means. S (hereinafter also referred to as a "second image carrier") are collectively transferred. In such secondary transfer, a transfer voltage of several kV is normally applied to ensure a sufficient transfer rate.

A transfer material S is supplied from a cassette 12 in which the transfer material S is stored to a conveying path by a pickup roller 13 . The transfer material S supplied to the conveying path is conveyed to the secondary transfer portion T' in synchronization with the four-color toner image transferred onto the intermediate transfer belt 7 by the conveying roller pair 14 and the registration roller pair 15. .
The toner image transferred to the transfer material S is fixed by the fixing device 9 to form, for example, a full-color image. The fixing device 9 has a fixing roller 91 having a heating means and a pressure roller 92, and fixes the unfixed toner image on the transfer material S by heating and pressurizing it. After that, the transfer material S is discharged out of the machine by a pair of conveying rollers 16, a pair of discharge rollers 17, and the like.

A cleaning unit 11 for the intermediate transfer belt 7 is arranged downstream of the secondary transfer portion T′ in the driving direction of the intermediate transfer belt 7, and the intermediate transfer belt 7 is not transferred to the transfer material S at the secondary transfer portion T′. Transfer residual toner remaining on the transfer belt 7 is removed.
As described above, the process of electrically transferring the toner image from the photosensitive member to the intermediate transfer belt and from the intermediate transfer belt to the transfer material is repeated. Further, by repeating recording on a large number of transfer materials, the electrical transfer process is further repeated.

[Electrophotographic belt]
As exemplified in FIG. 2, the electrophotographic belt 200 of the present embodiment is a laminate composed of at least two layers, a base layer 21 and a surface layer 22 . The surface layer 22 constitutes the toner carrying surface of the electrophotographic belt 200, namely the surface 200-1.
The configuration of the electrophotographic belt according to the present disclosure is not limited to the two-layer laminate described above. For example, a primer layer (not shown) for improving adhesion between the base layer 21 and the surface layer 22, a stress relaxation layer for suppressing cracking of the surface layer 22, and an intermediate layer for suppressing bleeding ( (none of which are shown) may be provided.

(base layer)
The shape of the base layer 21 is a roll-like or belt-like endless cylindrical shape.
Suitable materials for the base layer 21 include, for example, the following. Polyether ether ketone, polyethylene terephthalate, polybutylene naphthalate, polyester, polyimide, polyamide, polyamideimide, polyacetal, polyphenylene sulfide, polyvinylidene fluoride and the like.

Conductive compounds such as metal powder, conductive oxide powder, conductive carbon, lithium salt, and ionic liquid may be added to the resin for the base layer 21 to impart conductivity. In the following examples, polyimide with carbon black added was used from the viewpoint of being able to obtain excellent conductivity and environmental stability. can be
The film thickness of the base layer 21 is preferably 10 μm or more and 500 μm or less. If the thickness is less than 10 μm, the mechanical strength may be remarkably lowered, and if the thickness is more than 500 μm, the rigidity may become too strong, making it difficult to use as an intermediate transfer member.

(Surface layer)
The surface layer 22 is formed on the base layer 21, is the outermost layer of the intermediate transfer belt according to the present embodiment, and contains all of A, B, and C below.
A: Compound 1 having a structure represented by the above chemical structural formula (I) and a structure represented by the above chemical structural formula (II) (hereinafter also referred to as a graft copolymer)
B: Perfluoropolyether (hereinafter also referred to as PFPE)
C: Binder Resin The surface layer 22 may contain a photopolymerization initiator, a conductive substance, etc., in addition to the binder resin, PFPE, and graft copolymer described above.

<C: Binder resin>
As the binder resin, one or more resins selected from the group consisting of acrylic resins, methacrylic resins, and epoxy resins can be used. "One or more resins" includes mixed resins of resins selected from the above group.
The binder resin functions as a dispersion medium for PFPE. It is also a material for ensuring the adhesion of the surface layer to the base layer 21 and for ensuring the mechanical strength of the surface layer itself.

Among the binder resins described above, methacrylic resins and acrylic resins are preferably used because they can satisfactorily disperse PFPE constituting the surface layer 22 of the electrophotographic belt. Hereinafter, methacrylic resins and acrylic resins are collectively referred to as acrylic resins.
Examples of the polymerizable monomer for forming the acrylic resin include the following (i) or (ii). As the polymerizable monomer, it is also possible to use those marketed as paints.

(i) at least one acrylate selected from the group consisting of: pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, alkyl acrylate, benzyl acrylate, phenyl acrylate, ethylene glycol diacrylate, and bisphenol A diacrylate.

(ii) at least one methacrylate selected from the group consisting of: pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol hexamethacrylate, alkyl methacrylate, benzyl methacrylate, phenyl methacrylate, ethylene glycol dimethacrylate and bisphenol A dimethacrylate.

Among these, a high hardness is preferable in consideration of rubbing with other members such as a photoreceptor and a cleaning blade. For this reason, it is preferable to increase the hardness of the acrylic resin by using a large amount of a bifunctional or higher crosslinkable monomer.
Moreover, in order to form an acrylic resin from such a polymerizable monomer, there is a method of adding a photopolymerization initiator and polymerizing it with electron beams or ultraviolet rays.

The following are mentioned as a photoinitiator. Benzophenone, thioxanthone, benzyl dimethyl ketal, α-hydroxyketone, α-hydroxyalkylphenone, α-aminoketone, α-aminoalkylphenone, monoacylphosphine oxide, bisacylphosphine oxide, hydroxybenzophenone, aminobenzophenone, titanocene , oxime esters, oxyphenyl acetate esters, and other radical-generating photopolymerization initiators.
The content of the binder resin in the surface layer is adjusted to the total solid content of the surface layer 22 so that the surface layer has excellent strength and the outer surface of the surface layer has excellent toner releasability. is preferably 20% by mass or more and 70% by mass or less with respect to the mass of

<B: Perfluoropolyether>
Perfluoropolyether (hereinafter also referred to as PFPE) is an oligomer or polymer having perfluoroalkylene ether as a repeating unit.
Repeating units of perfluoroalkylene ether include repeating units of perfluoromethylene ether, perfluoroethylene ether, and perfluoropropylene ether. A commercially available product can be used as PFPE. Examples of the commercially available products include PFPE represented by structural formula (1) (e.g., Demnum S-200, Demnum S-65 (both trade names), manufactured by Daikin Industries, Ltd.), structural formula (2 ) represented by PFPE (e.g., Krytox GPL-107, Krytox GPL-106, Krytox GPL-105 (all trade names), manufactured by Chemours), represented by the structural formula (3) PFPE (e.g., Fomblin M60, Fomblin Z25 (both trade names), manufactured by Solvay Specialty Polymers), PFPE represented by Structural Formula (4) (e.g., Fomblin Y45, Fomblin Y25 (both (trade name), manufactured by Solvay Specialty Polymers), but are not limited to these.

（式（１）中、ｎは正の数であり、ｎは４０℃における動粘度が１０～３００ｍｍ^２／ｓの範囲を満たす範囲の数である。）

(In formula (1), n is a positive number, and n is a number within a range that satisfies the kinematic viscosity at 40° C. of 10 to 300 mm ² /s.)

（式（２）中、ｎ’は正の数であり、ｎ’は４０℃における動粘度が５～１２００ｍｍ^２／ｓの範囲を満たす範囲の数である。）

(In formula (2), n' is a positive number, and n' is a number that satisfies the kinematic viscosity range of 5 to 1200 mm ² /s at 40°C.)

（式（３）中、ｎ”およびｍは各々正の数であり、ｍ／ｎ”は０．５以上２となる数であり、ｎ”＋ｍは４０℃における動粘度が１０～９００ｍｍ^２／ｓの範囲を満たす数である。）

(In formula (3), n″ and m are positive numbers, m/n″ is a number equal to or greater than 0.5 and 2, and n″+m is a kinematic viscosity at 40° C. of 10 to 900 mm ² / It is a number that satisfies the range of s.)

（式（４）中、ｎ'''およびｍ’は各々正の数であり、ｍ’／ｎ'''は２０以上１０００以下となる数であり、ｎ'''＋ｍ’は４０℃における動粘度が１０～７００ｍｍ^２／ｓの範囲を満たす範囲の数である。）

(In formula (4), n''' and m' are each positive numbers, m'/n''' is a number that is 20 or more and 1000 or less, and n'''+m' is It is the number in the range that satisfies the kinematic viscosity range of 10 to 700 mm ² /s.)

In addition, PFPE has a reactive functional group capable of forming a bond or a near-bond state with the binder resin and a non-reactive functional group unable to form a bond or a state near-bond with the binder resin. may have. Examples of such reactive functional groups include acryl groups, methacryl groups, and oxysilanyl groups. Moreover, examples of the non-reactive functional group include, for example, a hydroxyl group, a trifluoromethyl group, and a methyl group.
Examples of commercial products of PFPE having a reactive functional group as described above include the following. "Fluorolink MD700", "Fluorolink AD1700", "Fluorolink S10" (all trade names; manufactured by Solvay), and "Optool DAC" (trade name; manufactured by Daikin). “MD-500” is a PFPE having a methacrylic group as a functional group, and “Fluorolink AD1700” is a PFPE having an acrylic group as a functional group.

Commercially available products of PFPE having a non-reactive functional group as described above include “Fluororing D10H”, “Fluorolink D4000”, “Fomblin Z15” (all trade names, manufactured by Solvay), “Demnam S-20", "Demnum S-65", and "Demnum S200" (all trade names, manufactured by Daikin).

<A: Compound 1>
Compound 1 according to component A has a structure represented by chemical structural formula (I) and a structure represented by chemical structural formula (II). The compound 1 functions as a dispersant for dispersing PFPE in the binder resin. The graft copolymer according to compound 1 has both a first unit represented by the following chemical structural formula (I) and a second unit represented by the following chemical structural formula (II).
The first unit is a site that has excellent affinity with PFPE, while the second unit has excellent affinity with the fixing resin. Also, the first unit has a perfluoromethyl group as a side chain. As a result, the introduction of oxygen atoms to reduce the number of consecutive carbon atoms in the perfluoroalkyl group to 3 or less is considered to compensate for the decrease in the ability of PFPE to disperse in the binder resin. Conceivable. As a result, compound 1 according to the present disclosure can better disperse the low surface free energy PFPE in the binder resin.

Examples of the linking group R1 in the chemical structural formula (I) include an alkylene group having 1 to 6 carbon atoms, a carbon atom, a hydrogen atom, a nitrogen atom, and an oxygen atom, and constituting the main chain. Examples include groups having 6 or less atoms. Specifically, for example, an alkylene group having 1 to 6 carbon atoms (eg, —CH ₂ —, —CH ₂ CH ₂ —), or a combination of a methylene group (CH ₂ ) and an ethylene group (CH ₂ CH ₂ ) Groups such as those represented by the following structural formula (i) bonded with a urethane bond (--OC(=O)NH--) can be mentioned. In Structural Formula (1), the main chain means --C--O--C--N--C--C--.
(i)
_-CH2OC ( ₌ O) _NHCH2CH2-

Examples of the linking group R4 in the chemical structural formula (II) include groups having 9 or less atoms constituting the main chain. For example, a group composed of a carbon atom, a hydrogen atom, an oxygen atom and a sulfur atom and having 9 or less atoms constituting the main chain, and a carbon atom, a hydrogen atom, a nitrogen atom and an oxygen atom and sulfur atoms and the number of atoms constituting the main chain is 9 or less. Specific examples of such groups are shown in structural formulas (ii) to (iv) below. In the structural formula (ii), the main chain means -S-C-C-O-C-C-O-C-. In Structural Formula (iii), the main chain means -S-C-C-C-N-C-C-O-C-. In Structural Formula (iv), the main chain means -S-C-C-N-C-O-C-.

(ii)
-SCH ₂ C(=O)OCH ₂ CH(OH)CH ₂ OC(=O)-
(iii)
_-SCH2CH2C ( ₌ O) _{NHCH2CH2OC (} =O)-
(iv)
-SCH ₂ C(=O)NHCH ₂ CH ₂ OC(=O)-

The peak top molecular weight of Compound 1 is preferably 20,000 or more and 40,000 or less.
By having a numerical range related to the above peak top molecular weight, a high steric hindrance effect can be exhibited and aggregation between PFPEs can be effectively suppressed.
Compound 1 can also be defined as an acrylic resin or methacrylic resin grafted with a group having a perfluoroalkyl group having 3 carbon atoms. Such compounds can be obtained by copolymerizing macromonomers and monofunctional monomers. Here, the macromonomer is a compound having a higher molecular weight than general monomers and having a reactive group. Among such macromonomers, a graft copolymer can be obtained by polymerizing a macromonomer having one polymerizable functional group per molecule and a monomer having one polymerizable functional group per molecule. .

The electrophotographic belt according to the present disclosure will be described in more detail below with specific non-limiting examples.

<Preparation of macromonomer>
<<Macromonomer No. 1>>
A macromonomer having a methyl methacrylate segment (product name: AA-6; manufactured by Toagosei Co., Ltd., R3 and R5: —CH ₃ , number average molecular weight: 6000) was used as macromonomer No. prepared as 1.
<<Macromonomer No. 2>>
The materials shown in Table 1 below were added to a glass flask equipped with a reflux condenser, and the flask was replaced with nitrogen while maintaining the temperature at 15° C. with a water bath.

After that, the temperature of the water bath was adjusted so that the temperature of the reaction solution was 85° C. in a nitrogen atmosphere, and the polymerization reaction was carried out for 5 hours. The polymerization reaction was stopped by cooling with ice to obtain a solution in which the compound represented by the chemical formula (III) was dissolved.

Next, 60 parts by mass of toluene was added, and triethylamine was 0.5 wt% with respect to the amount of tert-butyl methacrylate monomer, and hydroquinone monomethyl ether was 200 ppm with respect to the amount of tert-butyl methacrylate monomer. did. Glycidyl methacrylate was added in a molar amount 10 times the acid value of the obtained chemical formula (III), and reacted at a temperature of 110° C. for 11 hours. The reaction was stopped by cooling with water, n-hexane was added, and a precipitate was obtained by centrifugation. Thereafter, drying was performed under reduced pressure for 3 hours at a temperature of 80° C. and a temperature of 1325 Pa or less to obtain macromonomer No. 1 represented by formula (IV). got 2.

<<Macromonomer No. 3>>
Macromonomer No. Macromonomer No. 2 except that the glycidyl methacrylate used in preparing Macromonomer No. 2 was changed to glycidyl acrylate. 2 and macromonomer No. 2 represented by the chemical formula (V). got 3.

<<Macromonomer No. 4>>
Tert-butyl methacrylate monomer to methyl methacrylate monomer,
Thioglycolic acid to 3-mercaptopropionic acid,
glycidyl methacrylate to 2-isocyanatoethyl methacrylate,
Triethylamine to zirconium (IV) acetylacetonate,
10 times molar amount to 2 times molar amount,
11 hours of reaction at a temperature of 110 ° C. to a reaction of 24 hours at a temperature of 50 ° C.,
Macromonomer no. A macromonomer was prepared in the same manner as in 2. Macromonomer No. 1 represented by the chemical formula (VI). Got 4.

<<Macromonomer No. 5>>
Polymer Source's POLY (METHYL METHACRYLATE) MACROMONOMER, ΩVINYL-TERMINATED grade having a number average molecular weight of 2800 was used as macromonomer No. prepared as 5.

<<Macromonomer No. 6>>
Polymer Source's POLY (METHYL METHACRYLATE) MACROMONOMER, ΩVINYL-TERMINATED with a number average molecular weight of 9900 was used as macromonomer No. prepared as 6.
Macromonomer No. The structures of 2-6 are shown in Table 2. The value of m was obtained from the peak area ratio of 1H NMR in _CDCl3 solvent.

<Preparation of Monomer Having Perfluoro Structure>
<< Perfluoro structure-containing monomer No. 1>>
1H,1H-Perfluoro(2,5-dimethyl-3,6-dioxanonanoyl) acrylate having a structure represented by the following chemical formula (VIII) was added to perfluoro structure-containing monomer No. 1. Perfluoro structure-containing monomer No. 1 is a material that provides the structure shown in chemical structural formula (I). This perfluoro structure-containing monomer No. The structure according to chemical formula (I) formed by 1 is where R1 is a methylene group ( _CH2 ) and R2 is a hydrogen atom (H).

<< Perfluoro structure-containing monomer No. 2>>
The materials in Table 3 below are mixed in a glass flask equipped with a stirrer, a reflux condenser, a nitrogen gas inlet tube, a constant temperature bath and a thermometer at a temperature of 20 ° C. under a nitrogen atmosphere for 30 minutes, and then heated to 50 ° C. It was warmed and reacted for 24 hours. As a result, the perfluoro structure-containing monomer No. 1 represented by the chemical formula (VII) was obtained. got 2.

<Preparation of graft copolymer>
<<Graft copolymer No. 11>>
The materials shown in Table 4 below are mixed in a glass flask equipped with a stirrer, a reflux condenser, a nitrogen gas inlet tube, a constant temperature bath and a thermometer at 20 ° C. under a nitrogen atmosphere for 30 minutes, and then reacted. The liquid was heated to 85 to 90° C. and reacted for 5 hours. The reaction was stopped by cooling with ice, and 1500 parts by mass of 2-propanol was added to obtain a precipitate. This precipitate was washed with a mixed solvent of n-butyl acetate:2-propanol=1:5 and dried at a temperature of 80° C. under a reduced pressure of 1325 Pa or less for 3 hours to obtain macromonomer No. 1. 1 and perfluoro structure-containing monomer No. 1; Graft copolymer No. 1, which is a copolymer with No. 11 was obtained.

<<Graft copolymer No. 21, 22, 31, 32, 41, 51, 52, 61, 62>>
Graft copolymer 11 was prepared in the same manner as for graft copolymer 11, except that the blending amounts of the macromonomer species, perfluoro structure-containing monomer species, and 1,1'-azobis(1-acetoxy-1-phenylethane) were as shown in Table 5. and graft copolymer No. 21, 22, 31, 32, 41, 51, 52, 61 and 62 were prepared.

<<Graft copolymer No. 90>>
Perfluoro structure-containing monomer No. 1 was changed to 2,2,3,3,4,4,4-heptafluorobutyl acrylate having a structure represented by the following chemical formula (IX). A graft copolymer no. Got 90.

<Measurement of peak top molecular weight>
Table 6 shows the peak top molecular weight of the resulting graft copolymer. In addition, the peak top molecular weight was obtained by dissolving the measurement sample in tetrahydrofuran (hereinafter also referred to as THF) to prepare a solution having a concentration of 0.2% by mass, and then gel permeation chromatograph (hereinafter also referred to as GPC) apparatus GPC-104 ( (manufactured by Shodex). In addition, for molecular weight measurement, a column in which "GPC KF-603" and "GPC KF-604" manufactured by Shodex Co., Ltd. were connected one by one was used, and the column temperature was 40 ° C. and the THF flow rate was 1.0 mL / min. . The weight average molecular weight (Mw) of the sample was calculated from a calibration curve prepared in advance using a polystyrene standard substance (SM-105 manufactured by Shodex Co., Ltd.) with a known molecular weight.

[Example 1]
A paint A was obtained by mixing the materials shown in Table 7 below with a homogenizer.

The above paint A was applied onto the outer peripheral surface of an electrophotographic endless belt made of polyimide resin in which carbon black was dispersed, which was installed as an intermediate transfer belt in a full-color multifunction machine (trade name: imageRUNNER ADVANCE C5051; manufactured by Canon Inc.). was applied so that the dry film thickness would be 6 μm. Then, it was dried at a temperature of 70°C for 3 minutes. After that, using a high-pressure mercury lamp, ultraviolet rays are irradiated under the conditions of a peak illumination intensity of 200 mW/cm ² at a wavelength of 365 nm and an integrated light intensity of 2 J/cm ² to cure the coating film to form a surface layer, thereby forming an electrophotographic belt. No. got 1. The resulting electrophotographic belt was subjected to Evaluation 1 and Evaluation 2 below.

<Evaluation 1: Measurement of Hardness of Electrophotographic Belt>
The hardness of the electrophotographic belt was measured by the nanoindentation method. Specifically, a microhardness tester (trade name: PICODENTOR HM500; manufactured by Fisher Instruments) is used, a Vickers indenter is used as the indenter, and nanoindentation is performed under conditions where the indentation depth is 100 to 200 nm. A test was performed to determine the indentation hardness.

<Evaluation 2: Evaluation of electrophotographic properties>
Electrophotographic images were formed using the electrophotographic belts obtained in Examples 1 to 11 and Comparative Example 1, and the resulting electrophotographic images were evaluated.
Specifically, the electrophotographic belt was set as an intermediate transfer belt in a full-color multifunction machine (trade name: imageRUNNER ADVANCE C5760F; manufactured by Canon Inc.), and 30,000 electrophotographic images were continuously formed under the following conditions. Electrophotographic image formation was carried out by forming 97 sheets of the following solid image and subsequently forming 3 sheets of white solid image, repeating the cycle 300 times to form images on 30,000 sheets.
Solid image formed on 97 sheets: The amount of each of cyan (C), magenta (M), yellow (Y) and black (K) toner applied to the surface of the electrophotographic belt was 0.4 mg/cm ² , A solid image with an image ratio of 100% Three solid white images to be formed: A white solid image with an image ratio of 100% and an amount of each CMYK toner applied to the surface of the electrophotographic belt of 0 mg/cm ² A photographic image was formed under an environment of temperature: 30° C. and relative humidity: 80%. The paper used was “GF-C081” (A3 size, basis weight 81.4 g/m ² , thickness 97 μm, whiteness about 100%, manufactured by Canon Inc.).

Then, the solid white image with the applied amount of 0 mg/cm ² was visually observed. It was confirmed whether or not a patterned image was formed.
Then, when a streak-like image was observed, the cleaning blade in contact with the surface of the electrophotographic belt was visually observed. Then, it was confirmed whether or not the toner on the surface of the electrophotographic belt that had not been secondarily transferred (transfer residual toner) had been cleaned by the cleaning blade. Then, when it was confirmed that the transfer residual toner was not cleaned by the cleaning blade, it was determined that the streak-like image was caused by poor cleaning of the surface of the electrophotographic belt. This evaluation was made according to the following criteria based on the above observation results.
Rank A: A streak-like image caused by poor cleaning of the surface of the electrophotographic belt was not observed in the white solid image.
Rank B: A streak-like image caused by poor cleaning of the surface of the electrophotographic belt was observed in the white solid image.

[Examples 2 to 10]
As shown in Table 8, a paint was prepared in the same manner as in Example 1 except that the graft copolymer 11 was changed. 2-10 were obtained. The obtained electrophotographic belt was subjected to evaluation 1 and evaluation 2 described above.

[Example 11]
95 parts by mass of pentaerythritol triacrylate was changed to 40 parts by mass of bisphenol A type epoxy acrylate (EBECRYL 600 manufactured by Daicel-Ornex) and 55 parts by mass of pentaerythritol triacrylate. A coating material was prepared in the same manner as in Example 2 except for such changes. 11 was obtained. The obtained electrophotographic belt was subjected to evaluation 1 and evaluation 2 described above.

[Comparative Example 1]
Graft copolymer no. 11 to graft copolymer no. A paint was prepared in the same manner as in Example 1, except that the belt was changed to No. 90. Got 90. Electrophotographic belt No. thus obtained. 90 was subjected to Rating 1 and Rating 2 above. For evaluation 2, the solid white image formed at the 100th cycle had streaks due to poor cleaning, so image formation was stopped at the end of the 200th cycle.
Table 9 shows the evaluation results of Examples 1 to 11 and Comparative Example 1.

Electrophotographic Belt No. 1 according to Comparative Example 1; It is believed that the results of evaluation 1 and evaluation 2 of 90 are due to the different surface free energies of the comb graft copolymers. That is, comb graft copolymer No. The surface free energy of 90 is different from the surface free energy of the comb-shaped graft copolymer used in the examples, which is considered to be due to the low ability of PFPE to disperse in the binder resin. In electrophotographic belt No. 90, PFPE in the surface layer was not finely dispersed, so that the hardness of the surface layer was lowered, as is clear from the result of evaluation 1. As a result, the surface layer was worn by repeated cleaning of the surface of the electrophotographic belt, and PFPE in the surface layer was lost along with the wear. Therefore, it is presumed that the cleanability of the surface of the electrophotographic belt deteriorated over time.
On the other hand, in the electrophotographic belt according to each example, the PFPE in the surface layer is finely dispersed, so that the surface layer maintains high hardness. Therefore, even if the surface of the electrophotographic belt is repeatedly cleaned, the surface layer is less likely to be worn. In addition, since the PFPE is finely dispersed, even if the surface layer is worn, the PFPE domains are present substantially uniformly in the thickness direction of the surface layer, so that the surface of the electrophotographic belt can be repeatedly cleaned. It is thought that it became difficult to decrease even with the use of
In order to show the difference in surface free energy between the graft copolymers of Examples and Comparative Examples, the graft copolymer Nos. 21 thin film and graft copolymer no. Table 10 shows the n-hexadecane contact angle for 90 thin films.

Table 11 shows a list of CAS numbers and manufacturer names of materials indicated by common names for the materials used in the examples.

Py: yellow image forming unit Pm: magenta image forming unit Pc: cyan image forming unit Pk: black image forming unit 1Y: yellow photosensitive drum 1M: magenta photosensitive drum 1C: cyan photosensitive drum 1K: black photosensitive drum 4Y: yellow developing device 4M : Magenta developing device 4C: Cyan developing device 4K: Black developing device 5Y, 5M, 5C, 5K: Primary transfer rollers Ty, Tm, Tc, Tk: Primary transfer section 73: Secondary transfer inner roller 100: Image forming apparatus 2Y, 2M, 2C, 2K: Chargers 3Y, 3M, 3C, 3K: Laser scanner 11: Transfer belt cleaning unit 12: Paper feed cassette 15: Registration roller pair 7: Intermediate transfer belt 8: Secondary transfer outer roller 9: Fixing device 91: fixing film 92: pressure roller S: transfer material

Claims (8)

An electrophotographic belt having at least a base layer and a surface layer,
An electrophotographic belt, wherein the surface layer contains the following A, B, and C:
A: Compound 1 having a structure represented by the following chemical structural formula (I) and a structure represented by the following chemical structural formula (II)
B: Perfluoropolyether C: Binder resin

. The linking group R1 is
an alkylene group having 1 to 6 carbon atoms, or
2. The belt for electrophotography according to claim 1, wherein the group is composed of carbon, hydrogen, nitrogen and oxygen atoms and has 6 or less atoms constituting the main chain. 3. The electrophotographic belt according to claim 1, wherein the linking group R1 is a group represented by the following structural formula (i):
(i)
_-CH2OC ( ₌ O) _NHCH2CH2- . The linking group R4 is
or
4. The electrophotography according to any one of claims 1 to 3, wherein the group is composed of carbon, hydrogen, nitrogen, oxygen and sulfur atoms and has a main chain of 9 or less atoms. belt for. The electrophotographic belt according to any one of claims 1 to 4, wherein the linking group R4 is any one selected from the group consisting of the following structural formulas (ii) to (iv):
(ii)
-SCH ₂ C(=O)OCH ₂ CH(OH)CH ₂ OC(=O)-
(iii)
_-SCH2CH2C ( ₌ O) _{NHCH2CH2OC (} =O)-
(iv)
-SCH ₂ C(=O)NHCH ₂ CH ₂ OC(=O)-. 6. The electrophotographic belt according to claim 1, wherein the binder resin is one or more resins selected from the group consisting of acrylic resins, methacrylic resins, and epoxy resins. 7. The electrophotographic belt according to claim 1, wherein the compound 1 has a peak top molecular weight of 20,000 or more and 40,000 or less. An image carrier that carries a toner image, and an intermediate transfer belt that carries and conveys the toner image that has been primarily transferred from the image carrier so as to secondarily transfer the toner image onto a transfer material, wherein the intermediate transfer belt is the electrophotographic belt according to any one of claims 1 to 7.

Images