JP2008203724A - Image forming apparatus and image forming method - Google Patents

Abstract

An image forming method without fogging using a liquid developer containing a solid content of high concentration, and a compact image forming apparatus for carrying out the image forming method.
A photosensitive member, a charging member for charging the photosensitive member, a writing member for forming an electrostatic latent image on the charged photosensitive member, a transfer member for transferring an image on the photosensitive member to a recording member, and recording An image forming apparatus provided with a fixing member for fixing an image transferred to a member is provided with a die head provided on the downstream side of the writing member in the rotation direction of the photosensitive member so as to face the photosensitive member, and contains a solid and a carrier liquid. The developer is applied to the photosensitive member on which the electrostatic latent image is formed by the die head and developed, and the surface of the photosensitive member is covered with a surface protective layer made of a cured product of the fluorine-containing photocurable composition. To.
[Selection] Figure 1

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a printer, and an image forming method.

An electrostatic latent image liquid developing apparatus for developing an electrostatic latent image formed on an image support with toner, wherein the toner has a high viscosity of 100 to 10,000 mPa · s in which the toner is dispersed in a high concentration. The liquid developer is applied to the developing belt supported by a plurality of rollers as a thin layer having a thickness of 5 to 40 μm, and the liquid developer applied to the developing belt is brought into contact with the image support. An electrostatic latent image liquid developing device including a developing unit that supplies the liquid developer to the latent image surface of the image support has been studied (for example, see Patent Document 1). An image forming apparatus including the liquid developing device forms an image with a small amount of liquid developer, but has a problem that a mechanism for forming a thin layer of the liquid developer on the developing belt is complicated and maintenance is not easy.
On the other hand, an image forming apparatus for developing an electrostatic latent image by supplying a high-concentration liquid developer on a developer carrying member to the latent image carrying member, and facing the developer carrying member with a gap A developer thin layer means for forming a high-concentration liquid developer layer on the developer carrier, and the liquid developer layer on the developer carrier and the latent image carrier before contact with the liquid. An excess liquid removing means for removing excess developer in the developer layer is provided, and a gap between the developer carrier and the developer thin layer means is provided between the developer carrier and the developer thin layer means. An image forming apparatus that forms an electric field for causing electrophoresis of toner particles in the supplied liquid developer toward the surface of the developer carrying member has been studied (for example, see Patent Document 2). The liquid developer toner particles that have been electrophoresed on the surface of the developer carrying member and from which excess liquid has been removed are agglomerated, and the liquid developer that has not been developed is collected and reused. The crushing process is required. Therefore, the image forming apparatus is large.
Further, the liquid developer adheres to the non-developing portion of the photoreceptor of the conventional image forming apparatus, and as a result, fog is generated in the image formed by the conventional image forming apparatus. Although the technique (for example, refer patent document 3) by which the coating liquid of this is apply | coated to a coating surface and a uniform coating layer is formed was common, the application to the image forming apparatus of a die head was not examined.
Japanese Patent Laid-Open No. 7-209922 JP-A-10-339990 JP 2006-281103 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fog-free image forming method using a liquid developer containing a high concentration of solid content, and a compact image forming apparatus for carrying out the image forming method.

The present invention relates to a photoreceptor, a charging member for charging the photoreceptor, a writing member for forming an electrostatic latent image on the charged photoreceptor, a transfer member for transferring an image on the photoreceptor to a recording member, and a recording An image forming apparatus provided with a fixing member for fixing an image transferred to a member, wherein a die head is provided on the downstream side of the writing member in the rotation direction of the photosensitive member so as to face the photosensitive member, and includes a solid content and a carrier liquid. The liquid developer is applied to a photoreceptor on which an electrostatic latent image is formed by a die head and developed, and the surface of the photoreceptor is coated with a surface protective layer made of a cured product of a fluorine-containing photocurable composition. The image forming apparatus.
The image forming apparatus of the present invention can form an image with a small amount of liquid developer having a high solid content concentration and viscosity, and has a compact configuration. Furthermore, since the liquid developer hardly adheres to the non-image portion of the photosensitive member of the image forming apparatus of the present invention, the image forming apparatus of the present invention forms an image without fogging, and the image forming apparatus of the present invention is not sensitive. The body cleaning means is small.
In a preferred embodiment of the present invention, the photoreceptor of the image forming apparatus is an organic photoreceptor or an amorphous silicon photoreceptor.
In another preferred embodiment of the present invention, the photoreceptor of the image forming apparatus is positively charged. The positive charging of the photoconductor of the image forming apparatus suppresses the generation of ozone.
In another preferred embodiment of the present invention, the gap formed between the die head of the image forming apparatus and the photosensitive member is 20 to 100 μm. The image forming apparatus of the present invention in which the gap formed between the die head and the photoreceptor is set in the above range forms a homogeneous image with no sharpness and high sharpness.

  The present invention relates to a process in which a photosensitive member coated with a surface protective layer made of a cured product of a fluorine-containing photocurable composition is charged by a charging member, on a photosensitive member in which an electrostatic latent image is charged by a writing member. A photosensitive member on which an electrostatic latent image is formed by a die head in which a liquid developer containing a solid content and a carrier liquid is provided on the downstream side of the writing member in the rotation direction of the photosensitive member. The image forming method includes the steps of coating and developing, and transferring the image formed on the photosensitive member to the recording member and then fixing the image transferred to the recording member.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating the overall configuration of a tandem image forming apparatus according to an embodiment of the present invention.
Liquid developer storage control units 6Y, 6C, 6M are prepared by using liquid developer storage units 6Y, 6C, 6M, which are produced by using yellow pigment (Y), cyan pigment (C), magenta pigment (M), and black pigment (K), respectively. Stored in 6B. The photoreceptors 1Y, 1C, 1M, and 1B, which are image carriers, are uniformly charged by the charger 2. Laser light modulated by the image signal is irradiated from the writing LED 3 to the uniformly charged photoreceptors 1Y, 1C, 1M, and 1B, and electrostatic latent images are formed on the photoreceptors 1Y, 1C, 1M, and 1B. Is formed. Each color liquid developer stored in the liquid developer storage control units 6Y, 6C, 6M, 6B is supplied from the die head 7 onto the photoreceptors 1Y, 1C, 1M, 1B on which electrostatic latent images are formed, Development is performed. At that time, a bias is applied between the die head 7 and the photoreceptors 1Y, 1C, 1M, and 1B.

  The images on the photoconductors 1Y, 1C, 1M, and 1B are transferred to the intermediate transfer belt 8 at the primary transfer position where the primary transfer roller 5 and the photoconductors 1Y, 1C, 1M, and 1B are in contact with each other via the intermediate transfer belt 8. Transcribed. After the primary transfer, the undeveloped liquid developer is removed by the photoconductor cleaning means 16, and the removed liquid developer passes through the liquid developer circulation path 19 to be liquid developer storage control units 6Y, 6C, 6M, 6B. To be recovered. Residual charges on the surfaces of the photoreceptors 1Y, 1C, 1M, and 1B from which the liquid developer has been removed are discharged by the discharging LED 4 in preparation for the next charging. The intermediate transfer belt 8 is an endless belt and is stretched between the driving roller 9 and the driven roller 10. The image on the intermediate transfer belt 8 transferred at the primary transfer position is secondarily transferred onto the recording member at the secondary transfer portion where the driving roller 9 and the secondary transfer roller 11 abut via the intermediate transfer belt 8. The The recording member is supplied from the paper feed cassette 12 and is conveyed to the secondary transfer portion through the conveyance path 13, and after the secondary transfer, the recording member is conveyed to the fixing roller pair 14 to fix the image. In the case of double-sided printing, the recording member is reversed after fixing and conveyed again to the secondary transfer section via the conveyance path 15 for double-sided printing, and recording on the back surface is performed. After the secondary transfer, the intermediate transfer belt 8 is cleaned by the intermediate transfer belt cleaning unit 18, and the secondary transfer roller 11 is cleaned by the secondary transfer roller cleaning unit 17.

FIG. 2 is a diagram illustrating the overall configuration of a tandem image forming apparatus according to another embodiment of the present invention.
Liquid developer storage control units 6′Y, 6 ′ are prepared by using liquid developer storage units 6′Y, 6 ′, which are produced by using yellow pigment (Y), cyan pigment (C), magenta pigment (M), and black pigment (K). C, 6′M, 6′B. The photoreceptors 1′Y, 1′C, 1′M, and 1′B, which are image carriers, are uniformly charged by the charger 2 ′. Laser light modulated by the image signal is irradiated from the writing LED 3 ′ to the uniformly charged photoreceptors 1′Y, 1′C, 1′M, 1′B, and the photoreceptor 1′Y, An electrostatic latent image is formed on 1′C, 1′M, 1′B. Each color liquid developer stored in the liquid developer storage control unit 6′Y, 6′C, 6′M, 6′B is transferred to the photosensitive member 1′Y on which an electrostatic latent image is formed from the die head 7 ′. 1′C, 1′M, 1′B are supplied and developed. At that time, a bias is applied between the die head 7 'and the photoreceptors 1'Y, 1'C, 1'M, 1'B.

  The conveyor belt 20 is an endless belt and is stretched between the driving roller 9 'and the driven roller 10'. The recording member is supplied from the paper feed cassette 12 ′ and is transported to the transport belt 20 through the transport path 13 ′. The images on the photoconductors 1′Y, 1′C, 1′M, 1′B are transferred to the photoconductors 1′Y, 1′C, 1′M, and 1′B. And these photosensitive members are transferred to the recording member at a transfer position where they contact with each other via the conveying belt 20. After the transfer, the recording member to which the image has been transferred is conveyed to the fixing roller pair 14 ', and the image is fixed. In the case of double-sided printing, the double-sided printing switching device 22 is activated, and the recording member is reversed via the double-sided printing conveyance path 15 ′ after fixing, and is conveyed again from the sheet feeding cassette 12 ′ to the transfer unit to the back side. Recording is performed. After the transfer, the undeveloped liquid developer is removed by the photoconductor cleaning means 16 ′, and the removed liquid developer passes through the liquid developer circulation path 19 ′ and the liquid developer storage control units 6′Y, 6′C. , 6′M, 6′B. Residual charges on the surfaces of the photoreceptors 1'Y, 1'C, 1'M, 1'B from which the liquid developer has been removed are neutralized by the neutralizing LED 4 'in preparation for the next charging.

A gap is formed between the die head and the photoreceptor. If the gap between the die head and the photoconductor is too small or too large, a good print image cannot be obtained. The gap between the die head and the photoreceptor is set to 20 to 100 μm.
The photosensitive member has an organic photosensitive layer or an inorganic photosensitive layer formed on a cylindrical or sheet-like conductive support, and the surface of the photosensitive layer opposite to the conductive support side is cured by the fluorine-containing photocurable composition. It has a structure coated with a surface protective layer made of a material. Specific examples of the conductive support include (1) a support made of a metal material such as aluminum, aluminum alloy, nickel, stainless steel, iron, and brass, and (2) an insulating substrate such as polyester, polyimide, polycarbonate, and glass. A support on which a conductive material such as the above metal or metal oxide is deposited by deposition or the like.

(Organic photoconductor)
Specific examples of the organic photosensitive layer are (1) a function-separated type laminated photosensitive layer in which a charge generation layer and a charge transport layer are sequentially laminated, and (2) a single-layer type photosensitive layer. Hereinafter, the single layer type organic photosensitive layer will be described. A coating liquid comprising an additive such as a charge generator, a charge transport agent, a sensitizer and a binder resin is applied onto the conductive support. Specific examples of the charge generating agent include phthalocyanine pigments, azo pigments, quinone pigments, perylene pigments, quinothiaton pigments, indigo pigments, bisbenzimidazole pigments, and quinacridone pigments. Preferred charge generating agents are phthalocyanine pigments and azo pigments. Specific examples of the charge transport agent are organic hole transport compounds such as hydrazone, stilbene, phenylamine, arylamine, diphenylbutadiene, and oxazole. Specific examples of the sensitizer are electron-withdrawing organic compounds such as paradiphequinone derivatives, naphthoquinone derivatives, and chloranil. Specific examples of the binder resin are thermoplastic resins such as polycarbonate resin, polyarylate resin, and polyester resin. A preferred binder resin is a polycarbonate resin.

  The composition ratio of each component is 40 to 75% by mass of the binder resin, 0.5 to 20% by mass of the charge generator, 10 to 50% by mass of the charge transport agent, and 0.5 to 30% by mass of the sensitizer. A preferable composition ratio is 45 to 65% by mass of the binder resin, 1 to 20% by mass of the charge generating agent, 20 to 40% by mass of the charge transporting agent, and 2 to 25% by mass of the sensitizer. Each component is pulverized with a stirrer such as a homomixer, a ball mill, a sand mill, an attritor, or a paint conditioner together with an organic solvent such as toluene or methyl ethyl ketone, and dispersed and mixed to prepare a coating solution. The coating solution is coated on a conductive support and then dried. Specific examples of the application method include dip coating, ring coating, and spray coating. The organic photosensitive layer after drying has a thickness of 15 to 40 μm, and a preferred thickness is 20 to 35 μm.

(Amorphous silicon photoconductor)
A specific example of the inorganic photosensitive layer is an amorphous silicon (a-Si) photoconductive layer. Specific examples of the material constituting the photoconductive layer of the a-Si photoconductor having the a-Si photoconductive layer include a-Si, amorphous silicon carbide (a-SiC), amorphous silicon nitride (a-SiN), Amorphous silicon oxide (a-SiO), amorphous silicon germanium (a-SiGe), amorphous silicon nitride carbide (a-SiCN), amorphous silicon nitride oxide (a-SiNO), amorphous silicon oxide carbide (a-SiCO), amorphous nitridation It is an a-Si-based or a-Si alloy-based photoconductive material such as silicon oxide carbide (a-SiCNO). Specific examples of the film forming method using these photoconductive materials are a glow discharge decomposition method, a sputtering method, a vapor deposition method, an ECR method, a photo CVD method, and a catalytic CVD method. In forming the film, hydrogen (H), fluorine (F) and / or chlorine (Cl) is contained in the film in an amount of 1 to 40 mol% for dangling bond termination.

  Periodic table group IIIa elements (hereinafter abbreviated as group IIIa elements), group Va elements (hereinafter abbreviated as group Va elements), carbon (C), nitrogen (N), oxygen (O) and other elements It is possible to adjust the characteristics such as the electrical characteristics (dark conductivity, photoconductivity, etc.) and optical band gap of the photoconductive layer. When an element such as C, N, or O is contained in the film, the content of the IIIa group element is 0.1 to 20,000 ppm, and the content of the Va group element is 0.1 to 10,000 ppm. When an element such as C, N, or O is not contained or contained in a trace amount in the film, the content of the IIIa group element is 0.01 to 200 ppm, and the content of the Va group element is 0.01 to 100 ppm. . The element concentration distribution of group IIIa element, group Va element, C, N, O, etc. may be provided with a gradient over the layer thickness direction. In that case, the average content of the entire layer may be within the above range. Desirable specific examples of the IIIa group element and the Va group element are boron (B) and phosphorus (P), respectively. Boron and phosphorus are excellent in covalent bonding, can change the semiconductor characteristics sensitively, and can provide excellent photosensitivity.

  The a-Si photoconductive layer may contain microcrystalline silicon (μc-Si). Inclusion of μc-Si increases the dark conductivity and photoconductivity of the photoconductive layer and increases the degree of freedom in designing the photoconductive layer. The a-Si-based photoconductive layer containing μc-Si is formed by changing the film formation conditions by the same formation method as described above. For example, the formation of the μc-Si-containing a-Si photoconductive layer by the glow discharge decomposition method is higher than the formation of the μc-Si-free a-Si photoconductive layer by the glow discharge decomposition method. Electric power is set high, and the hydrogen flow rate as a dilution gas increases. Further, the impurity element can be added to the μc-Si-containing a-Si photoconductive layer.

  In order to obtain better electrophotographic characteristics, a carrier injection blocking layer can be formed between the a-Si photoconductive layer and the substrate, or a surface layer can be formed on the surface of the photoconductive layer. The carrier injection blocking layer and the surface layer are formed of the a-Si photoconductive material. The carrier injection blocking layer and the surface layer formed of the a-Si photoconductive material have good matching properties with the a-Si photoconductive layer, and the film formation apparatus used when forming the a-Si photoconductive layer is used. The film is formed continuously following the formation of the a-Si photoconductive layer.

  The carrier injection blocking layer formed of the a-Si photoconductive material contains more group IIIa elements and / or Va group elements than the photoconductive layer, and the conductivity type of the carrier injection blocking layer is adjusted. The carrier injection blocking layer formed of the a-Si photoconductive material contains more elements such as C, N, and O than the photoconductive layer, and the resistance of the carrier injection blocking layer is high. The surface layer formed of the a-Si photoconductive material contains more elements such as C, N, and O than the photoconductive layer, and the resistance of the surface layer is high. By laminating the carrier injection blocking layer and the surface layer, charging ability, photosensitivity characteristics, durability, abrasion resistance and environmental resistance can be improved, and the excellent electrophotographic characteristics of the a-Si photoconductive layer can be further improved. .

  The thickness of the a-Si based photoconductive layer is 5 to 100 μm, preferably 15 to 80 μm. The thickness of the carrier injection blocking layer is 0.1 to 10 μm, preferably 0.3 to 5 μm. The thickness of the surface layer is 0.05 to 5 μm, preferably 0.1 to 2 μm.

(Fluorine-containing photocurable composition)
The fluorine-containing photocurable composition used for the surface coating of the photoreceptor of the image forming apparatus of the present invention is not limited to a specific composition. A specific example of the fluorine-containing photocurable composition is a composition containing a fluorinated alkyl group-containing (meth) acrylate. The fluorinated alkyl group-containing (meth) acrylate has a functional group having a fluorinated alkyl group at the terminal and two or more (meth) acryloyl groups, and the fluorine atom content in one molecule is 25% by mass. The molecular weight is 500 to 4000. The (meth) acryloyl group of the fluorinated alkyl group-containing (meth) acrylate is a generic term for an acryloyl group and a methacryloyl group. The fluorinated alkyl group of the (meth) acrylate containing a fluorinated alkyl group includes a perfluoroalkyl group in which all hydrogen atoms in the alkyl group are substituted with fluorine atoms, and a part of the hydrogen atoms in the alkyl group are fluorine. A functional group substituted with an atom (for example, HCF ₂ CF ₂ CF ₂ CF ₂ —) is generically referred to. The fluorinated alkyl group includes a fluorinated alkyl group containing an oxygen atom (for example, CF ₃ — (OCF ₂ CF ₂ ) ₂ —).
The fluorinated alkyl group-containing (meth) acrylate of the fluorinated alkyl group-containing (meth) acrylate is present at the end of the molecule and is not incorporated as part of the network when the fluorinated alkyl group-containing (meth) acrylate is crosslinked. The fluorinated alkyl group-containing (meth) acrylate has two or more (meth) acryloyl groups that become cross-linking points at the time of crosslinking, and when the fluorinated alkyl group-containing (meth) acrylate is cross-linked, a strong three-dimensional A network structure is formed.

The fluorinated alkyl group-containing (meth) acrylate contains 25% by mass or more of fluorine atoms. When the fluorine atom content is less than 25% by weight, the amount of fluorinated alkyl group-containing (meth) acrylate used is increased or the other fluorine atom content is high in order to develop oil repellency derived from fluorine atoms. It is necessary to use a reactive compound and / or a non-reactive compound in combination.
The molecular weight of the fluorinated alkyl group-containing (meth) acrylate is 500 to 4000. When the molecular weight is larger than 4000, the crosslink density of the cured product of the fluorine-containing photocurable composition is decreased, and the mechanical properties of the cured product are decreased. On the other hand, when the molecular weight is less than 500, the fluorine atom content of the cured product is reduced, and the oil repellency derived from the fluorine atoms is not sufficiently expressed.

〔式（１）中、Ｒは水素原子又は炭素数１〜４のアルキル基であり、Ｘはヘテロ原子を有していてもよいアルキレン鎖又は下記一般式（２）

〔式（２）中、Ｙは酸素原子又は硫黄原子であり、ｍとｎは同一でも異なっていてもよい１〜４の整数であり、Ｒｆ¹はフッ素化アルキル基である。〕
で表される連結基であり、Ｒｆはフッ素化アルキル基である。〕 Specific examples of the fluorinated alkyl group-containing (meth) acrylate are compounds represented by the following general formula (1) described in JP-A No. 2005-171238.

[In Formula (1), R is a hydrogen atom or a C1-C4 alkyl group, X is the alkylene chain which may have a hetero atom, or following General formula (2).

In [Equation (2), Y is an oxygen atom or a sulfur atom, m and n is an integer of 1 to 4 may be the same or different, Rf ¹ is a fluorinated alkyl group. ]
Rf is a fluorinated alkyl group. ]

X in the general formula (1) represents the following general formula (3)
_{- (CH 2) p -Z q} - (CH 2) r - (3)
In [Equation (3), Z is NR (R is a hydrogen atom or an alkyl group having 1 to 24 carbon atoms.), An oxygen atom, a sulfur atom or NR-SO ₂ (R is C24 hydrogen or C P is an integer of 0 to 4, q is 0 or 1, r is an integer of 0 to 20, and 1 ≦ p + r ≦ 20. And an alkylene chain represented by the formula:

X in the general formula (1) is a linking group represented by the general formula (2) [wherein Rf ¹ is C _n F _{2n + 1} (n is an integer of 1 to 20). ] Or an alkylene chain [However represented by the general formula (3), Z is NR (R is a hydrogen atom or an alkyl group having 1 to 24 carbon atoms.), An oxygen atom, a sulfur atom or NR-SO ₂ (R Is a hydrogen atom or an alkyl group having 1 to 24 carbon atoms), p is 1, q is 1, and r is an integer of 0 to 19. And Rf in the general formula (1) may be the same as or different from Rf ¹ C _n F _{2n + 1} (n is an integer of 1 to 20).

〔式（５）中、Ｙは酸素原子又は硫黄原子であり、ｍとｎは同一でも異なっていてもよい１〜４の整数であり、ＲｆとＲｆ¹は同一でも異なっていてもよいＣ_nＦ_2n+1（ｎは１〜２０の整数である。）である。〕で表される化合物（ａ２）とを、前記化合物（ａ１）１モルに対して、前記化合物（ａ２）を１．０〜（ｋ−２）モル〔ｋは前記化合物（ａ１）１分子中の平均（メタ）アクリロイル基数〕の割合でマイケル付加反応させて得られる化合物であり得る。 X in the general formula (1) is a linking group represented by the general formula (2) [wherein Y is a sulfur atom and Rf ¹ has 4, 6 or 8 carbon atoms. ] Or an alkylene chain represented by the general formula (3) [wherein Z is NR (R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), sulfur atom or NR-SO ₂ (R is carbon number) 1 to 6 alkyl groups), and Rf in the general formula (1) may have 4, 6 or 8 carbon atoms.
The fluorinated alkyl group-containing (meth) acrylate includes a compound (a1) having three or more (meth) acryloyl groups, and the following general formula (4):
_{Rf- (CH 2) r -Z-} H (4)
Wherein (4), r is an integer of 0 to 20, Rf is C _n F _{2n +} 1 _(n is an integer of 1 to 20.), Z is NR (R is a hydrogen atom or a carbon And an oxygen atom, a sulfur atom, or NR-SO ₂ (wherein R is a hydrogen atom or an alkyl group having 1 to 24 carbon atoms). Or a compound represented by the following general formula (5)

In [Equation (5), Y is an oxygen atom or a sulfur atom, m and n is an integer of 1 to 4 may be the same or different, Rf and Rf ¹ good be the same or different C _n F _{2n + 1} (n is an integer of 1 to 20). The compound (a2) is represented by 1.0 to (k-2) mol [k is in one molecule of the compound (a1) with respect to 1 mol of the compound (a1). The average (meth) acryloyl group number] can be a compound obtained by a Michael addition reaction.

The compound (a2) is a compound represented by the general formula (4) [wherein Z is NR (R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), a sulfur atom or NR-SO ₂ ( R is an alkyl group having 1 to 6 carbon atoms, and the carbon number n in Rf is 4, 6 or 8.] or a compound represented by the general formula (5) (wherein Y is sulfur) the atomic carbon number n of Rf and Rf in ¹ can be a 4, 6 or 8.).

〔式（６）中、Ｒ¹は水酸基、炭素数１〜２４のアルキル基、炭素数１〜２４のアルキルカルボニルオキシ基、ＣＨ₂＝ＣＨＣＯ₂ＣＨ₂−、ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯ₂ＣＨ₂−、繰り返し数が１以上で末端が水素原子、炭素数１〜１８のアルキル基で封鎖された（ポリ）オキシアルキレン基又は炭素数１〜１２のアルキロール基であり、Ｒ²は（メタ）アクリロイル基である。〕で表される化合物（ａ１−１）、下記一般式（７）

（式中、Ｒ²は（メタ）アクリロイル基であり、Ｒ³は水素原子又は炭素数１〜１８のアルキルカルボニル基であり、ｍは３〜６の整数であり、ｎは０〜３の整数であり、且つｍ＋ｎ＝６である。）で表される化合物（ａ１−２）、ウレタン（メタ）アクリレート（ａ１−３）、シアヌレート環含有トリ（メタ）アクリレート（ａ１−４）又はリン酸トリ（メタ）アクリレート（ａ１−５）であり得る。 The compound (a1) having three or more (meth) acryloyl groups has the following general formula (6):

Wherein (6), R ¹ represents a hydroxyl group, an alkyl group having 1 to 24 carbon atoms, alkylcarbonyloxy group having 1 to 24 carbon _{atoms, CH 2 = CHCO 2 CH 2} -, CH 2 = C (CH 3) CO ₂ CH ₂ — is a (poly) oxyalkylene group or an alkylol group having 1 to 12 carbon atoms which is blocked with a hydrogen atom, an alkyl group having 1 to 18 carbon atoms and having a repeating number of 1 or more, and R ² is (Meth) acryloyl group. ] Compound (a1-1) represented by the following general formula (7)

Wherein R ² is a (meth) acryloyl group, R ³ is a hydrogen atom or an alkylcarbonyl group having 1 to 18 carbon atoms, m is an integer of 3 to 6, and n is an integer of 0 to 3. And m + n = 6), urethane (meth) acrylate (a1-3), cyanurate ring-containing tri (meth) acrylate (a1-4) or triphosphate It may be (meth) acrylate (a1-5).

The compound (a1) having three or more (meth) acryloyl groups has the general formula (6) [wherein R ¹ is a linear alkyl group having 1 to 4 carbon atoms, CH ₂ ═CHCO ₂ CH ₂ — CH ₂ = C (CH ₃ ) CO ₂ CH ₂ -or an alkylol group having 1 to 3 carbon atoms. A compound represented by the general formula (7): wherein R ³ is a hydrogen atom or an alkylcarbonyl group having 1 to 12 carbon atoms. Or a urethane (meth) acrylate obtained by reacting a hydroxyl group-containing (meth) acrylate having two or more (meth) acryloyl groups with an isocyanate compound having an alicyclic structure.

(Formation of a surface protective layer comprising a cured product of a fluorine-containing photocurable composition)
The photoconductive layer of the photoreceptor is coated with a fluorine-containing photocurable composition. Specific examples of the coating apparatus include an air knife coater, a kiss roll coater, a metering bar coater, a gravure roll coater, a reverse roll coater, a dip coater, a die coater, a spray, and a combination thereof. Subsequently, the fluorine-containing photocurable composition is polymerized and cured by light irradiation to obtain a photoreceptor coated with a surface protective layer made of a cured product of the fluorine-containing photocurable composition. During light irradiation, heat can be used as an energy source. In this case, a polymerization initiator such as azobisisobutyronitrile, benzoin peroxide, or methyl ethyl ketone peroxide cobalt naphthenate can be used in combination.
The light source for light irradiation is not particularly limited. Specific examples of light sources include germicidal lamps, fluorescent lamps for ultraviolet rays, carbon arc, xenon lamps, high-pressure mercury lamps for copying, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, electrodeless lamps, metal halide lamps, scanning electron accelerators, curtains Type electron accelerator.

The liquid developer carrier liquid used in the image forming apparatus of the present invention is a non-volatile oil such as vegetable oil, silicone oil, or liquid paraffin. Specific examples of vegetable oils are linseed oil, MO sunflower oil, rapeseed oil, divider oil, HOLL canola, safflower oil, olive oil, peanut oil, sesame oil, corn oil, soybean oil, cottonseed oil, safflower oil. The vegetable oil may be one kind or a mixture of plural kinds.
Since triglyceride having a fatty acid composition having a high proportion of unsaturated bonds such as oleic acid, linoleic acid and linolenic acid causes oxidative polymerization, the fixing means of the image forming apparatus of the present invention can be simplified. Further, when the image forming apparatus of the present invention is not used for a long period of time, the liquid developer in which the non-volatile oil is a carrier liquid is in contact with the liquid developer such as a transfer member, a cleaning member, and a photosensitive member. Does not stick to the surface of the device.
Table 1 shows the ratio (mass%) of various fatty acids in the fatty acid constituting the triglyceride in the vegetable oil used in the liquid developer of the present invention.

The concentration of the solid content contained in the liquid developer used in the image forming apparatus of the present invention is 10 to 50% by mass. The pigment contained in the liquid developer is a basic pigment treated with a resin and a basic polymer dispersant.
The liquid developer used in the image forming apparatus of the present invention may contain a charge control agent, a resin, a dispersant, an antioxidant and the like together with the basic pigment. Specific examples of charge control agents include tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate, tetra-n-butyl titanate, tetra-tert-butyl titanate, tetra-2-ethylhexyl titanate, tetraoctyl titanate, tetramethoxy titanium Titanium chelates such as titanyl acetyl acetate; isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) Titanate, tetra (2,2-diallyloxydylmethyl-1-butyl) bis (di-tridecyl), bis (dio (Cutyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, isopropyl tri (N-aminoethyl- Aminoethyl) titanate coupling agents such as titanate.

The acid value of the resin is 4-15. Specific examples of the resin include ethylene / vinyl acetate copolymer, polyester resin, styrene / acrylic resin, rosin modified resin, polyethylene, ethylene / acrylic acid copolymer, ethylene / maleic anhydride copolymer, polyvinylpyridine, polyvinylpyrrolidone. , Ethylene / methacrylic acid copolymer, and ethylene / acrylic acid ester copolymer. One or more resins selected from the above resins can be used.
A mixture containing a basic pigment, carrier liquid, oleic acid, etc. is dispersed with a dispersing machine such as an attritor, sand mill, ball mill, vibration mill, etc. to obtain a liquid developer used in the image forming apparatus of the present invention. It is done. The preferred primary particle diameter of the colored fine particles of the liquid developer used in the image forming apparatus of the present invention is 1 μm or less as the number average particle diameter.
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

(Adjustment of cyan MO sunflower oil developer)
Pigment Blue 15: 3 35 parts by mass of polyester resin (Plastic DL-90 manufactured by Dainippon Ink & Chemicals, Inc.) and polymer dispersant (Ajispur PB-822 manufactured by Ajinomoto Fine Techno Co., Ltd.) 65 parts by mass of the mixture mixed at a mass ratio of 2 was kneaded and pulverized to produce a cyan pigment. Next, 450 g of a zirconia ball having a diameter of 5 mm, MO sunflower oil (manufactured by Nisshin Oilio Group Co., Ltd., triglyceride component is 60.5% by mass), oleic acid (Kanto Chemical Co., Ltd.) )) 50 g, a dispersant (Ajinomoto Fine Techno Co., Ltd. Ajisper PA111) 0.11 g, and cyan pigment 35 g were added and dispersed and mixed for 24 hours at a rotational speed of 504 ppm using a commercially available stirrer Tornado SM type prober stirring blade. Thus, a cyan MO sunflower oil developer as a colorant dispersion was prepared.

(Adjustment of magenta MO sunflower oil developer)
The same procedure as for the cyan MO sunflower oil adjustment was performed, except that Pigment Red57: 1 was used instead of Pigment Blue15: 3 in the adjustment of the cyan MO sunflower oil developer, and a magenta MO sunflower oil developer was produced. It was done.

(Adjustment of yellow MO sunflower oil developer)
A yellow MO sunflower oil developer was prepared in the same manner as the cyan MO sunflower developer, except that Pigment Yellow 74 was used instead of Pigment Blue 15: 3 in the adjustment of the cyan MO sunflower oil developer. .

(Adjustment of black MO sunflower oil developer)
Preparation of cyan MO sunflower oil developer, except that basic processing carbon black (particle diameter 40 nm, nitrogen adsorption specific surface area 55 m ² / g) is used instead of Pigment Blue 15: 3 in the preparation of cyan MO sunflower oil developer The same operation was carried out to produce a black MO sunflower oil developer.

  Table 2 shows the viscosities and electrical resistances immediately after the production of the four-color MO sunflower oil developers. The viscosity was measured by a viscometer (VM-100A manufactured by CBC Co., Ltd.) at 25 ° C. and a humidity of 49%. The electrical resistance is an electrometer (MMAII-17B manufactured by Kawaguchi Electric Mfg. Co., Ltd.), for a measurement electrode liquid (LP-05 manufactured by Kawaguchi Electric Mfg. Co., Ltd.), and a measurement box (P-618 manufactured by Kawaguchi Electric Mfg. Co., Ltd.). Was measured at an applied voltage of 100V.

  Since the dispersibility of the pigment based on the acid-base interaction differs depending on the basicity of each pigment, the viscosity of the MO sunflower oil developer of each color is considered to be different.

(Adjustment of silicone oil developer)
The same operation as the adjustment of the MO sunflower oil developer was performed except that a silicone oil (KF-96-20 manufactured by Shin-Etsu Silicone Co., Ltd.) was used instead of the MO sunflower oil in the adjustment of the MO sunflower oil developer, Cyan, magenta, yellow and black silicone oil developers were prepared. Table 3 shows the viscosity and electrical resistance immediately after the production of the four-color silicone oil developers.

(Adjustment of liquid paraffin developer)
The same operation as the adjustment of the MO sunflower oil developer was performed except that liquid paraffin (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of the MO sunflower oil in the adjustment of the MO sunflower oil developer, and cyan, magenta , Yellow and black liquid paraffin developers were prepared. Table 4 shows the viscosity and electrical resistance immediately after the preparation of the four-color liquid paraffin developer.

(Preparation of positively charged organic photosensitive drum)
21 parts by mass of polycarbonate resin (manufactured by Teijin Chemicals Ltd., TS-2020), 2 parts by mass of metal-free phthalocyanine (manufactured by Dainippon Ink & Chemicals, Inc.), 10 parts by mass of hydrazone compound (manufactured by Annan Co., Ltd.), 3 , 5-dimethyl-3 ′, 5′-di (t) butyl-4,4′-diphenoquinone and 180 parts by mass of toluene were dispersed and mixed in a paint conditioner for 10 hours to prepare a coating solution.
The coating solution was applied to an aluminum tube having a diameter of 40 mm by a ring coating method and then dried to form a photosensitive layer having a thickness of 20 μm.

(Synthesis of UV curable fluororesin)
(Synthesis Example 1)
A 500 ml four-necked flask equipped with a water separation tube was charged with 33.5 g of trimethylolpropane, 123.0 g of 3-perfluorooctylpropionic acid (manufactured by Tosoh F-Tech Co., Ltd.), 50 g of toluene, and 50 g of cyclohexane. Then, 2.5 g of concentrated sulfuric acid was added, and azeotropic dehydration was performed for 12 hours. After confirming that 4.5 g of water was produced, the mixture was once cooled to 25 ° C., 45.0 g of acrylic acid and 0.4 g of hydroquinone were added, and further azeotropic dehydration was performed while blowing air. After confirming that 9.0 g of water was produced, it was cooled to 25 ° C. 150 g of toluene was added to the reaction solution, neutralized and washed with 30 g of 25% aqueous sodium hydroxide solution, and further washed 3 times with 40 g of 20% by mass brine. Under reduced pressure, toluene and cyclohexane were distilled off to obtain 170 g of a slightly yellow liquid. The slightly yellow liquid was dissolved in 150 ml of toluene and purified by silica gel chromatography. Then, under reduced pressure, toluene was distilled off at a water bath temperature of 50 ° C. or lower while blowing oxygen, thereby obtaining a fluorinated alkyl group-containing acrylate (Compound A-1) represented by the following structural formula (i).

(Synthesis Example 2)
Add 15.7 g (0.03 mol) of dipentaerythritol hydroxypentaacrylate, 2 g of triethylamine, and 10 g of ethyl acetate to a 200 ml reaction flask, and gradually add 28.8 g (0.06 mol) of perfluorooctylethyl mercaptan with stirring. (The reaction temperature rose to 35 ° C). After the addition was completed, the mixture was further stirred at 50 ° C. for 3 hours. After completion of stirring, 60 g of ethyl acetate was added, and the organic layer was washed with 100 ml of 1N hydrochloric acid. Further, after washing twice with 100 ml of water, the organic layer was separated. The reaction solvent was distilled off under reduced pressure using an evaporator under a condition of 50 ° C. or lower, and further dried with a vacuum pump, whereby a fluorinated alkyl group-containing acrylate represented by the structural formula (ii) (Compound A-2) Got.

(Synthesis Example 3)
To a 200 ml reaction flask was added 21.2 g (0.05 mol) of tris (acryloxyethyl) isocyanurate (Aronix M-315 manufactured by Toa Gosei Co., Ltd.), 1.0 g of triethylamine, and 15 g of ethyl acetate. 19.0 g (0.05 mol) of fluorohexylethyl mercaptan was added dropwise with stirring (the reaction temperature rose to 35 ° C.). After the addition, the mixture was further stirred at 50 ° C. for 3 hours, and the ethyl acetate and triethylamine were distilled off under reduced pressure at 50 ° C. or lower, whereby a fluorinated alkyl group-containing acrylate represented by the following structural formula (iii) (Compound A-3) Got.

合成したフッ素化アルキル基含有アクリレートの性状を表５に示す。 (Synthesis Example 4)
In Synthesis Example 3, instead of 21.2 g (0.05 mol) of tris (acryloxyethyl) isocyanurate (Aronix M-315 manufactured by Toa Gosei Co., Ltd.), 15.1 g (0. 05 mol) in the same manner as in Synthesis Example 3 except that 24.0 g (0.05 mol) of perfluorooctylethyl mercaptan was used instead of 19.0 g (0.05 mol) of perfluorohexylethyl mercaptan. A fluorinated alkyl group-containing acrylate (Compound A-4) represented by the structural formula (iv) was obtained.

Table 5 shows the properties of the synthesized fluorinated alkyl group-containing acrylates.

(Preparation of an organic photosensitive drum for oil repellent positive charging)
Each of the compounds A-1 to A-4 was prepared using the spray coating machine manufactured by Asahi Sunac Corporation under the coating conditions shown in Table 6, and the positively charged organic photosensitive drum photosensitive drum (Φ40) produced as described above. ) Was applied while rotating at 120 rpm. Next, the photosensitive drum was rotated at 120 rpm using an ultraviolet irradiation apparatus for rotating and drying a cylindrical tube (NPT 453 manufactured by Nippon Bunka Seiko Co., Ltd.), and the coating liquid was applied while irradiating ultraviolet rays at an irradiation dose of 160 mJ / cm ^2. Oil-repellent positively charged organic photosensitive drum No. 1-No. 4 was produced.

(Preparation of oil-repellent positive charging a-Si photosensitive drum)
Each of compounds A-1 to A-4 was rotated at 120 rpm using a spray coating machine manufactured by Asahi Sunac Co., Ltd. under the coating conditions shown in Table 7 at 120 rpm. It was applied while letting. Next, the photosensitive drum was rotated at 120 rpm using an ultraviolet irradiation apparatus for rotating and drying a cylindrical tube (NPT 453 manufactured by Nippon Bunka Seiko Co., Ltd.), and the coating liquid was applied while irradiating ultraviolet rays at an irradiation dose of 160 mJ / cm ^2. Oil-repellent positively charging a-Si photosensitive drum No. 2 dried for 20 seconds and coated with a surface protective layer. 5-No. 8 was produced.

(Example 1)
As the photoreceptor 1 of the tandem type image forming apparatus shown in FIG. 1 and the liquid developer storage control unit 6 was loaded with the above four color MO sunflower oil developers. A printing pattern including a color image of 5% of each color was used, and continuous printing was performed on 1000 sheets of transfer paper (EP-L fine coating 81.4 gsm manufactured by Mitsubishi Paper Industries Co., Ltd.). At that time, six 1.5 cm square solid portions were provided in the color image original so that the solid density was measured. The printing conditions were as follows.
Bias between die head and organic photoreceptor drum; 400V
Process speed: 206 m / min
Scorotron applied voltage: 5.5 kV
Mesh electrode potential: 600V
Developer discharge amount from die head; 0.75 mg / cm ²
Primary transfer voltage: 650V
Secondary transfer voltage: 1.5 kV
Fixing roller temperature: 120 ° C

The gaps between the die head and the organic photosensitive drum were set to 20 μm, 30 μm, 40 μm, 50 μm, 70 μm, 100 μm, 130 μm, 150 μm, and 200 μm.
The solid density (solid OD value) and print quality (shift, sharpness) of each color in the 1000th printed matter were evaluated. The solid density was measured with a reflection densitometer (model 530 manufactured by X-Rite). Fading was evaluated by visual observation (◯: no fading, Δ: fading on a part of the printing surface, x: fading on the entire printing surface). The sharpness was determined by measuring the unevenness of the 1.5 cm square edge portion of the printed portion with a laser microscope (VK-9700 manufactured by Keyence Corporation). The results are shown in Table 8.
If the gap between the die head and the organic photosensitive drum is too narrow or too wide, it can be said that the printing quality is deteriorated.

  As the photoreceptor 1 of the tandem type image forming apparatus shown in FIG. 2-No. 4 was mounted, and the same operation as described above was performed except that the gap between the die head and the organic photosensitive drum was set to 50 μm. The results are shown in Table 9.

(Example 2)
As the photoreceptor 1 of the tandem type image forming apparatus shown in FIG. 5-No. 8 was mounted, the gap between the die head and the a-Si photosensitive drum was set to 50 μm, and the same printing test as in Example 1 was performed except that the printing conditions were changed as follows. The results are shown in Table 10.
Bias between die head and a-Si photoreceptor drum; 400V
Process speed: 206 m / min
Scorotron applied voltage: 5.0 kV
Mesh electrode potential: 700V
Developer discharge amount from die head; 0.70 mg / cm ²
Primary transfer voltage: 650V
Secondary transfer voltage: 1.5 kV
Fixing roller temperature: 120 ° C
It can be said that an image formed by an image forming apparatus including an oil-repellent a-Si photosensitive drum has no blur and can have high sharpness.

(Example 3)
As the photoconductor 1 ′ of the tandem image forming apparatus shown in FIG. 1-No. 4 is mounted, and a polyimide belt (thickness 150 μm, volume electric resistance 2.1 × 10 ¹⁰ Ω · cm) is mounted as the conveying belt 20, and the above-mentioned four colors of MO sunflower oil are installed in the liquid developer storage control unit 6 ′. Developer was added. The gap between the die head and the organic photosensitive drum was set to 50 μm. A printing pattern including a color image of 5% of each color was used, and continuous printing was performed on ten transfer papers (EP-L fine coating 81.4 gsm manufactured by Mitsubishi Paper Industries Co., Ltd.). The printing conditions were as follows. The results are shown in Table 11.
Bias between die head and organic photoreceptor drum; 400V
Process speed: 200 m / min
Scorotron applied voltage: 5.5 kV
Mesh electrode potential: 600V
Amount of developer discharged from the die head; 0.65 mg / cm ²
Transfer voltage: 850V
Fixing roller temperature: 120 ° C

Example 4
As the photoreceptor 1 of the tandem type image forming apparatus shown in FIG. 1-No. 4 were mounted, and the four color silicone oil developers were placed in the liquid developer storage control unit 6. The gap between the die head and the organic photosensitive drum was set to 50 μm. A printing pattern including a color image of 5% of each color was used, and continuous printing was performed on 1000 sheets of transfer paper (EP-L fine coating 81.4 gsm manufactured by Mitsubishi Paper Industries Co., Ltd.). The printing conditions were as follows. The results are shown in Table 12.
Bias between die head and organic photoreceptor drum; 400V
Process speed: 206 m / min
Scorotron applied voltage: 5.5 kV
Mesh electrode potential: 600V
Developer discharge amount from die head; 0.75 mg / cm ²
Primary transfer voltage: 650V
Secondary transfer voltage: 1.5 kV
Fixing roller temperature: 120 ° C

(Example 5)
As the photoconductor 1 ′ of the tandem image forming apparatus shown in FIG. 1-No. 4 is mounted, and a polyimide belt (thickness 150 μm, volume electric resistance 2.1 × 10 ¹⁰ Ω · cm) is mounted as the transport belt 20, and the liquid developer storage control unit 6 ′ has the above four liquid paraffins. Developer was added. The gap between the die head and the organic photosensitive drum was set to 50 μm. A printing pattern including a color image of 5% of each color was used, and continuous printing was performed on ten transfer papers (EP-L fine coating 81.4 gsm manufactured by Mitsubishi Paper Industries Co., Ltd.). The printing conditions were the same as in Example 3. The results are shown in Table 13.

Schematic diagram of tandem image forming device Schematic diagram of tandem image forming device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 '... Photoconductor 2, 2' ... Charger 3, 3 '... Writing LED 4, 4' ... Static elimination LED, 5 ... Primary transfer roller, 6, 6 '... Liquid developer storage Control unit 7, 7 '... Die head, 8 ... Intermediate transfer belt, 9, 9' ... Drive roller, 10, 10 '... Driven roller, 11 ... Secondary transfer roller, 13, 13' ... Conveyance path, 14, 14 '... Fixing roller pair, 15, 15' ... Conveying path for duplex printing, 16, 16 '... Photoconductor cleaning means, 17 ... Secondary transfer roller cleaning means, 18 ... Intermediate transfer belt cleaning means, 19, 19' ... Liquid Developer circulation path, 20... Conveyor belt, 21... Transfer roller, 22.

Claims (5)

A photosensitive member, a charging member that charges the photosensitive member, a writing member that forms an electrostatic latent image on the charged photosensitive member, a transfer member that transfers an image on the photosensitive member to a recording member, and a transfer member that is transferred to the recording member An image forming apparatus provided with a fixing member for fixing an image,
A die head is provided on the downstream side of the writing member in the rotation direction of the photosensitive member so as to face the photosensitive member.
A liquid developer containing a solid content and a carrier liquid is applied to a photoreceptor on which an electrostatic latent image is formed by a die head, and development is performed.
An image forming apparatus in which a photoreceptor surface is coated with a surface protective layer made of a cured product of a fluorine-containing photocurable composition. The image forming apparatus according to claim 1, wherein the photoconductor is an organic photoconductor or an amorphous silicon photoconductor. The image forming apparatus according to claim 1, wherein the photosensitive member is positively charged. The image forming apparatus according to claim 1, wherein a gap formed between the die head and the photosensitive member is 20 to 100 μm. A step in which a photosensitive member coated with a surface protective layer made of a cured product of a fluorine-containing photocurable composition is charged by a charging member;
Forming an electrostatic latent image on a photosensitive member charged by a writing member;
A liquid developer containing a solid content and a carrier liquid is applied to the photosensitive member on which an electrostatic latent image is formed by a die head provided on the downstream side of the writing member in the rotational direction of the photosensitive member so as to face the photosensitive member. The steps performed,
An image forming method in which an image formed on a photosensitive member is transferred to a recording member, and then the image transferred to the recording member is fixed.

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