A modified polycarbonate coating for a photosensitive drum and a method for preparing the same

Abstract

The application relates to the technical field of coatings, and discloses a modified polycarbonate coating for a photosensitive drum and a preparation method thereof. The modified polycarbonate coating for the photosensitive drum comprises the following raw materials in weight components: 74.95-81.99 parts of a solvent, 10-15 parts of a modified polycarbonate resin, 8-10 parts of a charge transport material, and 0.01-0.05 parts of silicon oil. The preparation method comprises the following steps: adding the modified polycarbonate resin into tetrahydrofuran solvent, stirring and dispersing, adding the charge transport material and the silicon oil into the tetrahydrofuran solvent, and stirring and uniformly mixing to obtain the modified polycarbonate coating for the photosensitive drum. The prepared modified polycarbonate coating can solve the problem of bottom ash appearing in long-time charging and discharging in the prior art, and has a wide application prospect in the photosensitive drum.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a modified polycarbonate coating for photosensitive drums and its preparation method. Background Technology

[0002] As printers and multifunction printers become increasingly faster and longer-lasting, the requirements for the photoelectric performance of the photoconductor drum (OPC) are also becoming more stringent. However, during use, a gray background may appear on the printed surface. This gray background is caused by two main reasons. Firstly, the charge transfer efficiency is low, meaning that after rapid continuous printing, the charging potential of the OPC differs significantly from the original charging potential, and the original charging potential does not reach the predetermined value under a certain charging voltage, resulting in a gray background on the printed surface. Secondly, after the coating wears down, it cannot release the charge normally, causing residual charge to attract toner, thus producing a gray background.

[0003] The charge transport material used in traditional charge transport layers is TPD (N,N'-diphenyl-N,N'-bis(p-tolyl)benzidine), which has a transport rate of 1.1 × 10⁻⁶. -5 cm 2 / V·S, relatively slow, and as the thickness increases, the original charging potential cannot meet the requirements, and the printed surface is prone to background gray, which cannot guarantee both durability and print quality. Polycarbonate (PC) is a commonly used resin for photosensitive drums. During use, it has good insulation properties under continuous exposure conditions and is easier to maintain surface potential, but its abrasion resistance is poor. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the problems of low charge transfer efficiency and poor wear resistance of coatings in existing technologies, which lead to the formation of background gray during long-term charge and discharge, this invention provides a modified polycarbonate coating for photosensitive drums and its preparation method. By using a charge transport agent with a faster charge transfer rate and a modified polycarbonate resin with greater fatigue resistance, this invention can maintain a basically unchanged surface potential under continuous charge and discharge conditions, thereby solving the background gray problem.

[0006] (II) Technical Solution

[0007] A modified polycarbonate coating for a photosensitive drum, the modified polycarbonate coating for a photosensitive drum comprising the following raw materials by weight: 74.95-81.99 parts by weight of tetrahydrofuran solvent, 10-15 parts by weight of modified polycarbonate resin, 8-10 parts by weight of charge transport material, and 0.01-0.05 parts by weight of silicone oil;

[0008] The preparation method of the modified polycarbonate coating for the photosensitive drum includes the following steps:

[0009] Modified polycarbonate resin was added to tetrahydrofuran solvent and stirred to disperse it. Then, charge transport material and silicone oil were added and stirred to mix evenly to obtain modified polycarbonate coating for photosensitive drums.

[0010] Silicone oil can reduce the surface roughness of the charge transport layer of the photosensitive drum. The modified polycarbonate prepared in this invention also contains a silicon-oxygen structure, which not only has good compatibility with silicone oil, but also works with silicone oil to reduce surface wear during the photosensitive drum printing process, thereby indirectly improving the ability to maintain surface potential.

[0011] Preferably, the charge transport material is 4-(2,2-diphenylvinyl)-N,N-di-p-tolylaniline. Compared with traditional charge transport materials, 4-(2,2-diphenylvinyl)-N,N-di-p-tolylaniline has a faster charge transport rate, which can reduce the response time of the photosensitive layer and thus reduce fatigue problems in the continuous charge-exposure-charge cycle.

[0012] Preferably, the method for preparing the modified polycarbonate resin includes the following steps:

[0013] (1) 3,5-Dihydroxybenzaldehyde and aminopropyltriethoxysilane were added to an ethanol solution and refluxed for 5-8 hours under argon protection. After the reaction was completed, the mixture was dried to obtain phenolic hydroxysilane. The ratio of 3,5-dihydroxybenzaldehyde to aminopropyltriethoxysilane was 1 g:(1.6-1.8) g. In this reaction, the aldehyde group in 3,5-dihydroxybenzaldehyde reacted with the amino group in aminopropyltriethoxysilane via a Schiff base reaction to obtain phenolic hydroxysilane. The reaction formula is as follows:

[0014] ;

[0015] (2) Add graphene oxide and 66.7% acetic acid aqueous solution to tetrahydrofuran solution, stir and disperse, add phenol hydroxysilane at 70-75℃, reflux for 20-24h, wash with deionized water after the reaction is completed, and dry to obtain phenol hydroxy hyperbranched polysilane grafted graphene oxide; the ratio of graphene oxide to phenol hydroxysilane is 1g:(10-15)g.

[0016] In this reaction, the ethoxy group in the phenol-hydroxysilane undergoes hydrolysis to generate silanol, which can bond with the hydroxyl groups on the surface of graphene oxide through hydrogen bonds. Finally, it undergoes dehydration condensation. The remaining hydroxyl groups on the silanol undergo dehydration condensation with the silanols generated by the hydrolysis of other phenol-hydroxysilanes. This process is repeated until a hyperbranched structure is formed, resulting in phenol-hydroxyl hyperbranched polysilane-grafted graphene oxide. In other words, a polysilane film containing terminal phenolic hydroxyl groups is formed on the surface of graphene oxide, which can reduce the aggregation degree of graphene oxide and enhance its dispersion effect.

[0017] (3) Add diphenyl carbonate, bisphenol A, lithium acetate, and phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide to a flask, purge with nitrogen, and react at 200°C for 3-5 h. After the reaction is complete, cool to room temperature, dissolve with dichloromethane, wash with n-hexane, and dry to obtain modified polycarbonate resin. The ratio of the amount of diphenyl carbonate, bisphenol A, lithium acetate, and phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide is 1 g: (1-1.2) g: (0.00012-0.00015) g: (0.01-0.05) g.

[0018] In this reaction, the phenolic hydroxyl groups in hyperbranched polysilane-grafted graphene oxide undergo polymerization with PC monomers. This is not a simple physical blending, but rather the embedding of graphene oxide-containing structures into the polycarbonate molecular chain. This reduces graphene oxide precipitation and improves compatibility with polycarbonate, ensuring its uniform dispersion within the polycarbonate molecular chain. Firstly, graphene oxide possesses charge transport properties, compensating for the lack of charge transport properties in polycarbonate. In the preparation of modified polycarbonate coatings for photosensitive drums, it can synergistically assist other charge transport materials to form a vast charge transport pathway. This improves charge transport efficiency. Secondly, uniformly dispersed graphene oxide can enhance the mechanical properties of polycarbonate. The hyperbranched phenolic hydroxyl structures on the surface of graphene oxide can undergo polymerization reactions with other PC monomers to form a dense cross-linked network structure, which can also enhance the mechanical properties of the material. In other words, graphene oxide can act as a stress concentration point, and the dense cross-linked network structure can act as a stress dispersion structure. Both can absorb and disperse stress, improve the mechanical properties of the material, and enhance wear resistance. This means that under continuous long-term charge and discharge conditions, the surface potential can remain basically unchanged, thereby solving the problem of bottom graying.

[0019] (iii) Beneficial technical effects

[0020] This invention prepares a modified polycarbonate resin that, firstly, reduces the agglomeration degree of graphene oxide, improving its compatibility with coatings during preparation; secondly, utilizes the charge transport effect of graphene oxide to form a uniformly dispersed charge transport network structure in the coating, synergistically improving charge transport efficiency; and thirdly, by preparing a phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide, which produces a large, dense cross-linked network structure when polymerized with PC monomers, this cross-linked network structure can synergistically improve the mechanical properties of the coating with graphene oxide, thereby enhancing the coating's wear resistance.

[0021] This invention improves the charge transport efficiency of coatings by utilizing a charge transport network structure formed by graphene oxide and charge transport materials, and enhances the wear resistance of coatings through cross-linked network structures, graphene oxide structures, and silicone oil. In other words, by using a charge transport network structure that forms a faster charge transport rate and a modified polycarbonate resin that is more fatigue-resistant, this invention can maintain a basically unchanged surface potential under continuous charge and discharge conditions, thereby solving the problem of undercoat graying. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Preparation method of graphene oxide: 1.5g of graphite and 9g of potassium permanganate were added to a flask, and then a mixed solution of 180mL H2SO4 and 20mL H3PO4 was added. The mixture was stirred at 50℃ for 12h. After the reaction was completed, the mixture was cooled to room temperature, and a mixed solution of 200g ice water and 1.5g H2O2 was added. The mixture was stirred and centrifuged. The mixture was then mixed with deionized water, 30% hydrochloric acid aqueous solution, and ethanol in sequence, centrifuged, filtered, and the residue was retained. The residue was then mixed with diethyl ether, filtered, and dried to obtain graphene oxide.

[0024] Example 1

[0025] (1) 1 g of 3,5-dihydroxybenzaldehyde and 1.6 g of aminopropyltriethoxysilane were added to an ethanol solution, and the mixture was refluxed for 8 h under argon protection. After the reaction was completed, the mixture was dried to obtain the desired product. Phenolic hydroxysilane ;

[0026] (2) 0.1 g of graphene oxide and 0.6 g of 66.7% acetic acid aqueous solution were added to tetrahydrofuran solution and stirred to disperse. 1 g of phenolic hydroxyl silane was added to the solution at 75 °C and the mixture was refluxed for 22 h. After the reaction was completed, the mixture was washed with deionized water and dried to obtain phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide.

[0027] (3) 10g of diphenyl carbonate, 10g of bisphenol A, 0.0012g of lithium acetate and 0.1g of phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide were added to a flask, nitrogen gas was introduced, and the reaction was carried out at 200℃ for 3h. After the reaction was completed, the temperature was lowered to room temperature, dissolved with dichloromethane, washed with n-hexane, and dried to obtain modified polycarbonate resin.

[0028] (4) According to the weight, 10 parts of modified polycarbonate resin are added to 81.99 parts of tetrahydrofuran solvent, stirred and dispersed, and then 8 parts of 4-(2,2-diphenylvinyl)-N,N-di-p-tolylaniline and 0.01 parts of silicone oil are added and stirred and mixed evenly to obtain modified polycarbonate coating for photosensitive drum.

[0029] Example 2

[0030] (1) 1g of 3,5-dihydroxybenzaldehyde and 1.6g of aminopropyltriethoxysilane were added to an ethanol solution and refluxed for 7h under argon protection. After the reaction was completed, the solution was dried to obtain phenolic hydroxysilane.

[0031] (2) 0.1 g of graphene oxide and 0.6 g of 66.7% acetic acid aqueous solution were added to tetrahydrofuran solution and stirred to disperse. 1.2 g of phenolic hydroxyl silane was added to the solution at 75 °C and the mixture was refluxed for 20 h. After the reaction was completed, the mixture was washed with deionized water and dried to obtain phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide.

[0032] (3) 10g of diphenyl carbonate, 12g of bisphenol A, 0.0014g of lithium acetate and 0.3g of phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide were added to a flask, nitrogen gas was introduced, and the reaction was carried out at 200℃ for 5h. After the reaction was completed, the temperature was lowered to room temperature, dissolved with dichloromethane, washed with n-hexane, and dried to obtain modified polycarbonate resin.

[0033] (4) According to the weight, 13 parts of modified polycarbonate resin are added to 77.96 parts of tetrahydrofuran solvent, stirred and dispersed, and then 9 parts of 4-(2,2-diphenylvinyl)-N,N-di-p-tolylaniline and 0.04 parts of silicone oil are added and stirred and mixed evenly to obtain modified polycarbonate coating for photosensitive drum.

[0034] Example 3

[0035] (1) 1 g of 3,5-dihydroxybenzaldehyde and 1.8 g of aminopropyltriethoxysilane were added to an ethanol solution and refluxed for 5 h under argon protection. After the reaction was completed, the solution was dried to obtain phenolic hydroxysilane.

[0036] (2) 0.1 g of graphene oxide and 0.6 g of 66.7% acetic acid aqueous solution were added to tetrahydrofuran solution and stirred to disperse. 1.5 g of phenolic hydroxyl silane was added to the solution at 70 °C and the mixture was refluxed for 24 h. After the reaction was completed, the mixture was washed with deionized water and dried to obtain phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide.

[0037] (3) 10g of diphenyl carbonate, 11g of bisphenol A, 0.0015g of lithium acetate and 0.5g of phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide were added to a flask, nitrogen gas was introduced, and the reaction was carried out at 200℃ for 4h. After the reaction was completed, the temperature was lowered to room temperature, dissolved with dichloromethane, washed with n-hexane, and dried to obtain modified polycarbonate resin.

[0038] (4) According to the weight, 15 parts of modified polycarbonate resin are added to 74.995 parts of tetrahydrofuran solvent, stirred and dispersed, and then 10 parts of 4-(2,2-diphenylvinyl)-N,N-di-p-tolylaniline and 0.05 parts of silicone oil are added and stirred and mixed evenly to obtain modified polycarbonate coating for photosensitive drum.

[0039] Comparative Example 1

[0040] The difference between this comparative example and Example 1 is that in step (4), N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine is used instead of 4-(2,2-diphenylvinyl)-N,N-di-p-tolylaniline.

[0041] Comparative Example 2

[0042] The difference between this comparative example and Example 1 is that in step (4), 3,3'-bis[p-tolyl]amino]biphenyl is used instead of 4-(2,2-diphenylvinyl)-N,N-bisp-tolylaniline.

[0043] Comparative Example 3

[0044] The difference between this comparative example and Example 1 is that in step (4), polycarbonate PCZ400 is used instead of modified polycarbonate resin.

[0045] The coating was applied to a 30*357cm aluminum tube. The resulting photosensitive drum was cured at 110℃ for 2 hours and then stored in a dark environment at 20±2°C and 50±10% humidity for 24 hours. A PDT-2000 electrical performance tester was used, with a charging voltage of 6.9KV, increased to 800±10V, and VO representing the initial charging potential. The voltage was set to 0.12uJ / cm. 2 0.3uj / cm 2 0.6uj / cm 2 Three exposure energies were used to measure the residual potential (VL) value of the photosensitive drum.

[0046] Table 1:

[0047]

[0048] Referring to the testing standard for background gray in GB / T 10073-2021, a whiteness meter is used for testing. The lower the whiteness meter test value, the higher the background gray level of the printed document. Level 0 is the best, and level 2 is the worst.

[0049] Table 2:

[0050]

[0051] As shown in Tables 1 and 2, the modified polycarbonate coating prepared in this invention exhibits good charge transport performance when applied to photosensitive drums. Furthermore, the superior charge transport effect and improved wear resistance of the coating enhance the background gray level of the printed document, solving the problem of background graying caused by prolonged charging and discharging in existing technologies. In Table 2, a larger V0 change value indicates a weaker surface voltage maintenance capability after printing tests, resulting in more severe background graying. Therefore, the modified polycarbonate coating prepared in this invention has broad application prospects in photosensitive drums.

[0052] The embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A modified polycarbonate coating for a photosensitive drum, characterized in that, The modified polycarbonate coating for the photosensitive drum comprises the following raw materials by weight: 74.95-81.99 parts by weight of tetrahydrofuran solvent, 10-15 parts by weight of modified polycarbonate resin, 8-10 parts by weight of charge transport material, and 0.01-0.05 parts by weight of silicone oil. The preparation method of the modified polycarbonate coating for the photosensitive drum includes the following steps: Modified polycarbonate resin was added to tetrahydrofuran solvent and stirred to disperse it. Then, charge transport material and silicone oil were added and stirred to mix evenly to obtain modified polycarbonate coating for photosensitive drums. The charge transport material is 4-(2,2-diphenylvinyl)-N,N-di-p-tolylaniline; The preparation method of the modified polycarbonate resin includes the following steps: (1) 3,5-dihydroxybenzaldehyde and aminopropyltriethoxysilane were added to an ethanol solution and refluxed under the protection of argon. After the reaction was completed, the solution was dried to obtain phenolic hydroxysilane. The ratio of 3,5-dihydroxybenzaldehyde to aminopropyltriethoxysilane was 1 g: (1.6-1.8) g. (2) Add graphene oxide and acetic acid aqueous solution to tetrahydrofuran solution, stir and disperse, add phenol hydroxysilane at 70-75℃, reflux for 20-24h, wash with deionized water after the reaction is completed, dry to obtain phenol hydroxy hyperbranched polysilane grafted graphene oxide, wherein the ratio of graphene oxide to phenol hydroxysilane is 1g:(10-15)g; (3) Add diphenyl carbonate, bisphenol A, lithium acetate, and phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide to a flask, purge with nitrogen, and react at 200°C for 3-5 h. After the reaction is complete, cool to room temperature, dissolve with dichloromethane, wash with n-hexane, and dry to obtain modified polycarbonate resin. The ratio of the amount of diphenyl carbonate, bisphenol A, lithium acetate, and phenolic hydroxyl hyperbranched polysilane-grafted graphene oxide is 1 g: (1-1.2) g: (0.00012-0.00015) g: (0.01-0.05) g.

2. The modified polycarbonate coating for photosensitive drums according to claim 1, characterized in that, In (1), the reflux reaction time is 5-8 hours.

3. The modified polycarbonate coating for photosensitive drums according to claim 1, characterized in that, In (2), the mass fraction of the acetic acid aqueous solution is 66.7%.

Images