Additive of charge generation material in organic photoconductor and organic photoconductor

Abstract

The invention relates to an additive of a charge generation material in an organic photoconductor and the organic photoconductor, and belongs to the technical field of organic photoconductors. Aiming at the technical problems that Y crystal form titanyl phthalocyanine serving as a charge generation material in a charge generation layer in an organic photoconductor is large in dark attenuation and low in sensitivity in a high-temperature and high-humidity environment, bottom ash of a printed product is caused, and printing is light, a fluorine-containing polyurethane-acrylate copolymer and a benzotriazole-zinc chelate are added as additives; the weather resistance of the organic photoconductor is improved, so that the organic photoconductor keeps good performance in a high-temperature and high-humidity environment; the structural formula of the fluorine-containing polyurethane-acrylate copolymer is as shown in the following formula (I); in the formula (I), Rf is a perfluorinated linear alkyl group, and the values of m, n and k are all integers.

Description

TECHNICAL FIELD

[0001] The present application relates to an additive of charge generating material in organic photoconductor and organic photoconductor, belongs to the technical field of organic photoconductor. BACKGROUND

[0002] The laminated organic photoconductor (OPC) generally includes a support and a photosensitive layer formed on the support. The laminated photosensitive layer obtained by sequentially laminating a charge generation layer (CGL) and a charge transport layer (CTL) from the support side is generally used as the photosensitive layer. In order to suppress the injection of charges from the support side to the photosensitive layer side, to suppress the occurrence of image defects such as black spots, a primer layer (UCL) is generally disposed between the support and the photosensitive layer.

[0003] At present, Y-titanium phthalocyanine (Y-TiOPc) is generally used as a charge generating material in the charge generation layer (CGL) of the OPC drum core, although it has the characteristics of high photosensitivity, good charge generating ability and stability, etc., but under high temperature and high humidity conditions, especially when the temperature is greater than or equal to 35℃ and the relative humidity is greater than or equal to 80%RH, the following problems are prone to occur: moisture causes the charge trap density to rise, the surface potential decay accelerates, the image is blurred, and the bottom gray is formed; the Y-type high photosensitive crystal form of TiOPc is easy to transform into the low-activity α-type, the light response ability decreases, and the printing is shallow. SUMMARY

[0004] In order to solve the technical problems of large dark decay, low sensitivity, print bottom gray and printing shallow of the laminated organic photoconductor using Y-titanium phthalocyanine as a charge generating material under high temperature and high humidity environment, the purpose of the present application is to provide an additive of charge generating material in organic photoconductor and organic photoconductor. For Y-titanium phthalocyanine as a charge generating material in the charge generation layer of the organic photoconductor, by adding fluorine-containing polyurethane-acrylate copolymer and benzotriazole-zinc chelate as an additive, the weather resistance of the organic photoconductor is improved, and the organic photoconductor maintains good performance under high temperature and high humidity environment.

[0005] In order to achieve the purpose of the present application, the following technical solutions are provided.

[0006] An additive of charge generating material in organic photoconductor, the charge generating material is Y-titanium phthalocyanine (Y-TiOPc), and the additive is fluorine-containing polyurethane-acrylate copolymer and benzotriazole-zinc (BTA-Zn) chelate; the structure of the fluorine-containing polyurethane-acrylate copolymer is shown in the following formula (I);

[0007] Formula (I), In formula (I), Rf is a perfluorinated straight-chain alkyl group, preferably the carbon number of the alkyl group is 4-7, more preferably 6; for example, when the carbon number of the alkyl group is 6, the alkyl group is -C6F 13 , and when the carbon number of the alkyl group is 7, the alkyl group is -C7F 15 . m is an integer, preferably the value is 1-3, more preferably 3; n is an integer, preferably the value is 5-8, more preferably 6; k is an integer, preferably the value is 2-4, more preferably 2.

[0008] Further, the mass of the fluorine-containing polyurethane-acrylate copolymer is 5%-20% of the mass of the Y crystal type titanyl phthalocyanine, more preferably 10%-20%; the mass of the benzotriazole-zinc chelate is 0.5%-3% of the mass of the Y crystal type titanyl phthalocyanine, more preferably 1%.

[0009] An organic photoconductor, which is a high-temperature and high-humidity resistant laminated organic photoconductor, is provided on a conductive substrate and sequentially comprises a primer layer, a charge generation layer and a charge transport layer from inside to outside, wherein the primer layer is in contact with the conductive substrate. The charge generation material used in the charge generation layer is Y crystal type titanyl phthalocyanine, and an additive is added, wherein the additive is the fluorine-containing polyurethane-acrylate copolymer and the benzotriazole-zinc (BTA-Zn) chelate of the present application.

[0010] Advantages (1) The present application provides an additive for a charge generation material in an organic photoconductor, which solves the technical problems of a large dark decay, low sensitivity, and a light print in a high-temperature and high-humidity environment of a laminated organic photoconductor using Y-type titanyl phthalocyanine as a charge generation material by adding a specific fluorine-containing polyurethane-acrylate copolymer and a benzotriazole-zinc chelate as an additive, thereby improving the weather resistance of the organic photoconductor and improving the print quality.

[0011] (2) The present application provides an additive for a charge generation material in an organic photoconductor, wherein the fluorine-containing polyurethane-acrylate copolymer as a hydrophobic polymer wraps TiOPc particles through intermolecular hydrogen bonds, inhibits Y→α crystal type conversion induced by heat and humidity, blocks water molecules from penetrating through the fluoroalkyl chain, and enhances the interlayer adhesion through the acrylate network; the benzotriazole-zinc chelate preferentially adsorbs on the defect sites on the surface of TiOPc, reduces the activation effect of moisture on charge traps, captures interfacial ionic impurities, repairs the charge trap energy level, and reduces the trap density.

[0012] (3) The application provides an additive of a charge generating material in an organic photoconductor, wherein the fluorine-containing polyurethane-acrylate copolymer has a structural formula as shown in formula (I), wherein Rf is a perfluorinated straight-chain alkyl group; when the carbon number is 4-7, the surface energy can be significantly reduced, and the moisture resistance is improved; however, when the carbon number is greater than 7, the Rf is too long, which can result in decreased compatibility and poor coating uniformity; when the carbon number is less than 4, the Rf is too short, and the surface energy reduction effect is not obvious. (4) The application provides an additive of a charge generating material in an organic photoconductor, wherein the fluorine-containing polyurethane-acrylate copolymer has a structural formula as shown in formula (I); when m is an integer of 1-3, the polyether segment provides flexibility and certain hydrophilicity, so that the chain segment flexibility and moisture resistance can be balanced, and the hydrophilicity is prevented from being too strong to cause increased moisture absorption when m is greater than 3. When n is an integer of 5-8, the long methylene chain can improve the molecular chain flexibility, reduce internal stress and enhance the dimensional stability under high temperature and high humidity; when n is less than 5, the chain segment is rigid and easy to crack; when n is greater than 8, the crosslinking density is reduced, and the temperature resistance is affected. When k is an integer of 2-4, the increase of k value can increase the molecular weight, enhance the crosslinking density and mechanical strength of the CG layer and improve the high temperature and high humidity resistance; however, when k is greater than 4, the system viscosity is increased, and the coating processability is decreased; when k is less than 2, the molecular weight is low, the crosslinking is insufficient, and the environmental resistance is poor.

[0013] (5) The application provides an organic photoconductor, which is a high temperature and high humidity resistant laminated organic photoconductor; the charge generating material used in the charge generating layer is Y crystal type oxygen titanium phthalocyanine; by adding specific fluorine-containing polyurethane-acrylate copolymer and benzotriazole-zinc chelate as additives, the technical problems of the laminated organic photoconductor with Y crystal type oxygen titanium phthalocyanine as the charge generating material, such as large dark decay, low sensitivity, print bottom gray and light printing in a high temperature and high humidity environment, can be solved, and the weather resistance of the organic photoconductor is improved, and the printing quality is improved. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The figure is a schematic diagram of the cross section of the organic photoconductor structure in the examples and comparative examples of the application.

[0015] Wherein, 1 is a conductive substrate, 2 is a primer layer, 3 is a photosensitive layer, 4 is a charge generating layer, and 5 is a charge transport layer. DETAILED DESCRIPTION

[0016] The application is further described below in combination with the drawings and specific embodiments, wherein the methods are all conventional methods without special instructions, and the raw materials can be obtained from public commercial channels or prepared according to the literature without special instructions.

[0017] As shown in the figure, the organic photoconductor of the present application is arranged on a conductive substrate 1, the organic photoconductor is sequentially arranged with a primer layer 2, a charge generation layer 4 and a charge transport layer 5 from inside to outside, the charge generation layer 4 and the charge transport layer 5 are collectively referred to as a photosensitive layer 3, and the primer layer 2 is in contact with the conductive substrate 1. Figure 1

[0018] The conductive substrate 1 is a conductive substrate commonly used in the prior art of the layered organic photoconductor. The conductive substrate 1 not only serves as an electrode, but also serves as a support for each layer of the organic photoconductor. The shape of the conductive substrate 1 is determined according to the application requirements, such as cylindrical, plate-shaped, film-shaped, etc. The material of the conductive substrate 1 is determined according to the application requirements, such as metal, for example, aluminum, stainless steel, nickel, etc.

[0019] The primer layer 2 is a primer layer commonly used in the prior art of the layered organic photoconductor. The primer layer 2 is a layer with resin as the main component, or a metal oxide film such as acid-resistant aluminum. The primer layer 2 has two main functions: one is to prevent charge injection from the conductive substrate 1 into the photosensitive layer 3, and the other is to cover the surface defects of the conductive substrate 1 and improve the adhesion between the photosensitive layer 3 and the conductive substrate 1.

[0020] The resin material of the primer layer 2 can be one or more of polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyamide resin, epoxy resin and polyester resin; preferably polyamide resin. In addition, metal oxides such as titanium dioxide and zinc oxide can also be added to the resin material in the primer layer 2 for use, and the metal oxide is preferably titanium dioxide. The thickness of the primer layer 2 is usually 0.5 μm ~ 10 μm, preferably 1 μm ~ 5 μm.

[0021] The charge generation layer 4 is a vacuum deposition layer of charge generation material, or a coating layer composed of charge generation material and resin binder. The charge generation layer 4 has the function of generating charges in response to light. The charge generation material used in the charge generation layer 4 of the present application is Y crystal type titanyl phthalocyanine, and the fluorine-containing polyurethane-acrylate copolymer and benzotriazole-zinc chelate of the present application are added as additives. The mass of the fluorine-containing polyurethane-acrylate copolymer is 5% ~ 20% of the mass of the Y crystal type titanyl phthalocyanine, more preferably 10% ~ 20%; the mass of the benzotriazole-zinc chelate is 0.5% ~ 3% of the mass of the Y crystal type titanyl phthalocyanine, more preferably 1%.

[0022] ​The resin binder of the charge generation layer 4 is one or more of the resin binders conventionally used in the charge generation layer 4 of the layered organic photoconductor of the prior art, such as polycarbonate resin, polyester resin, polyamide resin, polyurethane resin, vinyl chloride copolymer resin, vinyl acetate resin, phenoxy resin, polyvinyl acetal resin, polyvinyl butyral resin, polystyrene resin, polysulfone resin, diallyl phthalate resin, and methacrylate resin. The thickness of the charge generation layer 4 is usually 0.1 μm to 1 μm, and preferably 0.3 μm to 0.7 μm.

[0023] The charge transport layer 5 is a charge transport layer conventionally used in the layered organic photoconductor of the prior art, and is usually a coating layer composed of a charge transport material and a resin binder, which has the function of an insulating layer that maintains the charge of the photoreceptor in the dark; when the organic photoconductor receives light, the charge transport layer 5 is used to transport the charge generated by the charge generation layer 4 to the surface of the selenium drum. The charge transport material used can be one or more of hydrazone compounds, butadiene compounds, diamine compounds, indole compounds, indoline compounds, stilbene compounds, and distilbene compounds. The resin binder can be one or more of polycarbonate resins of bisphenol Z type, bisphenol ZC type, bisphenol C type, and bisphenol A type; polyarylate resins; styrene-butadiene copolymers; styrene-acrylonitrile copolymers; styrene-maleic acid copolymers; acrylate copolymers; styrene-acrylic acid copolymers; polyethylene resins; ethylene-vinyl acetate copolymers; chlorinated polyethylene resins; polyvinyl chloride resins; polypropylene resins; ionomer resins; vinyl chloride-vinyl acetate copolymers; alkyd resins; polyamide resins; polyurethane resins; polysulfone resins; diallyl phthalate resins; ketone resins; polyvinyl butyral resins; polyether resins; silicone resins; epoxy resins; phenol resins; urea resins; melamine resins; photo-curable resins such as epoxy acrylate and polyurethane-acrylate; and thermoplastic resins. The resin binder can be used alone or in combination of two or more. The thickness of the charge transport layer 5 is usually 3 μm to 50 μm, and preferably 10 μm to 30 μm, in order to maintain the effective surface potential in actual use.

[0024] The method for producing the organic photoconductor is a conventional method for producing the layered organic photoconductor of the prior art, in which a primer coating solution is applied to the conductive substrate 1 by a coating method, and a primer layer 2 is formed on the conductive substrate 1 after drying; a charge generation layer coating solution is applied to the primer layer 2, and a charge generation layer 4 is formed on the primer layer 2 after drying; and a charge transport layer coating solution is applied to the charge generation layer 4, and a charge transport layer 5 is formed on the charge generation layer 4 after drying, thereby producing the organic photoconductor on the conductive substrate 1.

[0025] Example 1 (1) Select the outer diameter of 30 mm, long 260.5 mm aluminum cylinder as the conductive base 1; The CM8000 (Mitsubishi Chemical, Japan) polyamide copolymer and titanium dioxide particles with an average particle size of 350 nm were dispersed and dissolved in the primer coating mixed solvent to obtain a primer coating solution; The mass ratio of the polyamide copolymer and titanium dioxide particles is 1:2; the mass fraction of the polyamide copolymer in the primer coating solution is 5%; the primer coating mixed solvent is composed of methanol, dichloromethane and propanol in a mass ratio of 5:3:2.

[0026] The primer coating solution was dip-coated on the outer circumferential surface of the conductive base 1, and then dried at 120°C for 20 min to form a primer coating 2 with a thickness of 1.5 μm on the conductive base 1.

[0027] (2) The Y crystal type oxygen titanium phthalocyanine, additives and polyvinyl butyral resin as a resin binder were ball-milled and dispersed in the charge generation layer mixed solvent, and the particle size was less than or equal to 300 nm to obtain a charge generation layer coating solution; The mass ratio of the Y crystal type oxygen titanium phthalocyanine and polyvinyl butyral resin is 2:1; the additives are fluorine-containing polyurethane-acrylate copolymer and benzotriazole-zinc chelate represented by formula (II), the mass of fluorine-containing polyurethane-acrylate copolymer is 5% of the mass of Y crystal type oxygen titanium phthalocyanine, and the mass of benzotriazole-zinc chelate is 1% of the mass of Y crystal type oxygen titanium phthalocyanine; the mass fraction of Y crystal type oxygen titanium phthalocyanine in the charge generation layer coating solution is 2%; the charge generation layer mixed solvent is composed of ethyl acetate and acetone in a mass ratio of 90:10.

[0028] Formula (II).

[0029] The charge generation layer coating solution was dip-coated on the surface of the primer coating 2, and dried at 90°C for 20 min to obtain a charge generation layer 4 with a thickness of 0.5 μm on the primer coating 2.

[0030] (3) The charge transport material N, N'-diphenyl-N, N'-di(3-methylphenyl)-1, 1'-biphenyl-4, 4'-diamine (m-TPD) and PCZ300 (Asahi Kasei, Japan) polycarbonate as a resin binder were dispersed and dissolved in dichloromethane to obtain a charge transport layer coating solution; the mass ratio of m-TPD and PCZ300 polycarbonate is 8:14; the mass fraction of m-TPD in the charge transport layer coating solution is 8%.

[0031] The charge transport layer coating solution was dip-coated onto the surface of the charge generation layer 4, and dried at 90°C for 60 min to obtain a charge transport layer 5 with a thickness of 20 μm on the charge generation layer 4, thus obtaining an organic photoconductor on the conductive substrate 1.

[0032] Example 2 Different from Example 1, in step (2), the mass of the fluorine-containing polyurethane-acrylate copolymer was 15% of the mass of the Y crystal form of titanium phthalocyanine; the rest was the same as Example 1.

[0033] Example 3 Different from Example 1, in step (2), the mass of the fluorine-containing polyurethane-acrylate copolymer was 15% of the mass of the Y crystal form of titanium phthalocyanine; the rest was the same as Example 1.

[0034] Example 4 Different from Example 1, in step (2), the mass of the fluorine-containing polyurethane-acrylate copolymer was 20% of the mass of the Y crystal form of titanium phthalocyanine; the rest was the same as Example 1.

[0035] Example 5 Different from Example 1, in step (2), the mass of the fluorine-containing polyurethane-acrylate copolymer was 15% of the mass of the Y crystal form of titanium phthalocyanine; the mass of the benzotriazole-zinc chelate was 0.5% of the mass of the Y crystal form of titanium phthalocyanine; the rest was the same as Example 1.

[0036] Example 6 Different from Example 1, in step (2), the mass of the fluorine-containing polyurethane-acrylate copolymer was 15% of the mass of the Y crystal form of titanium phthalocyanine; the mass of the benzotriazole-zinc chelate was 3% of the mass of the Y crystal form of titanium phthalocyanine; the rest was the same as Example 1.

[0037] Comparative Example 1 Different from Example 1, in step (2), no additives were added, only the Y crystal form of titanium phthalocyanine and polyvinyl butyral as a resin binder were ball-milled and dispersed in the charge generation layer mixed solvent; the rest was the same as Example 1.

[0038] Test and evaluation experiment The organic photoconductors prepared in Examples 1-6 and Comparative Example 1 were subjected to high temperature and high humidity environment resistance test and evaluation, and the evaluation method was as follows: First, the organic photoconductors prepared in Examples 1-6 and Comparative Example 1 were simultaneously placed in a 40°C / 95%RH environment for aging for 168 hours, and then subjected to dark decay testing using a Gentec 94 electrical property tester (manufactured by Gentec Corporation, Japan). Then, the organic photoconductors were applied to a Hewlett Packard M612 printer to print a 5% coverage text version and a solid black version, and the presence or absence of ghosting was observed and the print density was tested.

[0039] The results of the dark decay testing and the print quality of the organic photoconductors prepared in Examples 1-6 and Comparative Example 1 are shown in Table 1 below. Table 1

[0040] According to the test results, the dark decay of Comparative Example 1 reached 21 V / s, and heavy ghosting was observed in the 5% coverage text version, and the print density of the solid black version was only 1.2.

[0041] In Example 1, the mass of the fluorine-containing polyurethane-acrylate copolymer in the charge generation layer was 5% of the mass of the Y crystal type titanyl phthalocyanine, and the mass of the benzotriazole-zinc was 1% of the mass of the Y crystal type titanyl phthalocyanine, the dark decay was reduced to 11.5 V / s, slight ghosting was observed in the 5% coverage text version, and the print density of the solid black version was 1.29. In Examples 2-4, as the mass fraction of the fluorine-containing polyurethane-acrylate copolymer in the charge generation layer increased, the dark decay was reduced to 3 V / s-4 V / s, and ghosting no longer occurred; the print density reached 1.3 or more, indicating that the organic photoconductors prepared in Examples 2-4 had good high-temperature and high-humidity resistance.

[0042] In Examples 3, 5, and 6, as the mass fraction of the benzotriazole-zinc in the charge generation layer increased, the dark decay was 3 V-9 V, and when the mass fraction of the benzotriazole-zinc was 1%, the print density was 1.30 and there was no ghosting; when the mass fraction of the benzotriazole-zinc was 0.5% and 3%, the print density was less than 1.30, and there was slight ghosting.

[0043] The present application includes but is not limited to the above examples, any equivalent replacement or partial improvement made under the principle of the present application will be considered within the scope of protection of the present application.

Claims

1. An additive for a charge-generating material in an organic photoconductor, wherein the charge-generating material is γ-crystalline titanium phthalocyanine, characterized in that: The additives are fluorinated polyurethane-acrylate copolymer and benzotriazole-zinc chelate; the structural formula of the fluorinated polyurethane-acrylate copolymer is shown in formula (Ⅰ) below; Equation (Ⅰ), In formula (Ⅰ), Rf is a perfluorinated straight-chain alkyl group, and the values ​​of m, n and k are all integers.

2. The additive for charge-generating materials in an organic photoconductor according to claim 1, characterized in that: In formula (Ⅰ), the number of carbon atoms in the alkyl group in Rf is 4 to 7; m is 1 to 3; n is 5 to 8; and k is 2 to 4.

3. The additive for charge-generating materials in an organic photoconductor according to claim 1, characterized in that: In formula (Ⅰ), the alkyl group in Rf has 6 carbons; m is 3; n is 6; and k is 2.

4. An additive for charge-generating materials in an organic photoconductor according to any one of claims 1 to 3, characterized in that: The mass of the fluorinated polyurethane-acrylate copolymer is 5% to 20% of the mass of the Y-crystalline titanium phthalocyanine, and the mass of the benzotriazole-zinc chelate is 0.5% to 3% of the mass of the Y-crystalline titanium phthalocyanine.

5. An additive for charge-generating materials in an organic photoconductor according to claim 4, characterized in that: The mass of the fluorinated polyurethane-acrylate copolymer is 10% to 20% of the mass of the Y-type titanium phthalocyanine; the mass of the benzotriazole-zinc chelate is 1% of the mass of the Y-type titanium phthalocyanine.

6. An organic photoconductor, wherein the organic photoconductor is disposed on a conductive substrate, and a base coating layer, a charge generation layer, and a charge transport layer are sequentially disposed from the inside out, the base coating layer being in contact with the conductive substrate; the charge generation material used in the charge generation layer is γ-crystalline titanium phthalocyanine, characterized in that: The charge-generating material contains additives, which are fluorinated polyurethane-acrylate copolymers and benzotriazole-zinc chelates as described in any one of claims 1 to 5.

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