JPH01217351A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance mechanical strength and abrasion resistance of a photosensitive body and to improve printing resistance by using a specified silicone resin composition heat hardened as a binder resin. CONSTITUTION:The photosensitive body contains as the binder resin the silicone resin composition having a weight average molecular weight of 10<3>-10<6> obtained by hydrolyzing a mixture of methyltrialkoxysilane represented by formula I and tetraalkoxysilane represented by formula II, preferably, in an equal molar ratio, and heat hardening it. In formulae I and II, each of R1 and R2 is methyl or ethyl, thus permitting excellent durability and printing resistance never realized in the organic photosensitive body to be ensured.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an electrophotographic photoreceptor, and relates to mechanical strength of the photoreceptor,
ai! provides a long-life electrophotographic photoreceptor with excellent abrasion resistance and good printing durability. g, and in an electrophotographic photoreceptor having a photoconductive layer consisting of a photoconductive material and a binder on a conductive support, methyltrialkoxysilane of the following general formula (A) and the following general formula (B) are used as a binder resin. ) A silicone resin composition obtained by hydrolyzing a mixture of tetraalkoxysilanes and having a weight average molecular weight of 103 to 106 is thermally cured.

CHs S l (OR+) m......
・・・・・・・・・(n)S i (OR4)4 ・
・・・・・・・・・・・・・・・・・・・・・(B) However, RI and R1 are CH, or C, H.

The present invention provides an electrophotographic photoreceptor having a photoconductive layer consisting of a photoconductive material and a binder, which is obtained by hydrolyzing a mixture of methyltrialkoxysilane and tetraalcoquine silane as a binder resin with ion-exchanged water. By using a thermally cured silicone resin composition, the mechanical strength and abrasion resistance of the photoreceptor are improved, and a long-life electrophotographic photoreceptor with good printing durability is obtained.

[Industrial application field]

The electrophotographic photoreceptor of the present invention can be widely applied to copying machines, printers, and the like.

The electrophotographic process consists of charging, exposure, development, transfer, and fixing steps, and prints are obtained by repeating these steps. Charging applies a uniform positive or negative electrostatic charge to the surface of a photoconductive photoreceptor. In the subsequent exposure process, an electrostatic latent image corresponding to the image information is formed on the photoreceptor by irradiating it with laser light or the like to erase the surface charge on a specific portion. Next, this latent image is electrostatically developed with a powder ink called toner, thereby forming a visible image of the toner on the photoreceptor. Finally, this toner image is electrostatically transferred onto recording paper and fused using heat, light, pressure, etc. to obtain a printed matter.

[Conventional technology]

As photoreceptors for electrophotography, organic photoreceptors using organic substances are being actively developed. This is because it can be manufactured using a simple coating method, making it easy to reduce costs through mass production.Compared to inorganic photoreceptors that use inorganic substances such as selenium, this material has a wider range of material selection, so non-toxic compounds can be selected. It has the advantage of being maintenance-free by being disposed of by the user.

Generally, organic photoreceptors have lower sensitivity than inorganic photoreceptors such as selenium, but high sensitivity has been achieved by constructing a functionally separated laminated photoreceptor in which 11 charge generation 1- and a charge transport layer are laminated. Now you can.

Here, the charge generation layer has the function of absorbing incident light and generating electron-hole pairs (carrier bears), and the charge transport layer transports one of the carriers generated in the charge generation layer to the surface of the photoreceptor. It has the function of forming a latent image from static images. By separating the functions of the photoreceptor into two layers in this way, it is possible to select the most suitable compound for each function almost exclusively, and it is possible to dramatically improve the characteristics such as sensitivity and spectral characteristics. can.

The charge generation layer is formed by dissolving or dispersing in a binder resin a charge generation substance that absorbs light and generates carrier bears. Phthalocyanine pigments, azo pigments, etc. are generally used as the charge generating substance, and polyester, polyvinyl butyral, etc. are generally used as the binder resin.

Further, the charge generation layer can also be formed by vapor deposition of phthalocyanine or the like without using a binder resin. On the other hand, the charge transport layer is formed by dissolving a charge transport material that transports charge carriers in a binder resin. Charge transport material (CT
As M), electron-transporting CTMs (chloranil, bromanil, trinitrofluorenonato) that have a large electron affinity and easily transport electrons, and hole-transporting CTMs that have a small ionization potential and easily transport holes (pyrazoline,
hydrazone.

oxazole, etc.). Polyester, polycarbonate, etc. are generally used as the binder resin for the charge transport layer.

Furthermore, from the viewpoint of manufacturability, a single-layer type photoreceptor is used. This is a binder resin containing a charge generating substance, or a charge generating substance and a charge transporting substance.
N-vinylcarbazole)/2゜4.7-trinitrofluorenone-1/1 charge transfer complex photoreceptor, phthalocyanine particles dispersed in polyester resin, single-layer organic photoreceptor with added diazo pigment and hydrazone compound There are bodies, etc.

Generally, photoconductive layers such as a charge transport layer and a charge generation layer are formed by coating and drying a coating liquid in which the constituent materials of each layer are dissolved or dispersed in an organic solvent. The coating method is appropriately selected from the following, depending on the shape of the support, the doctor blade method, the souffle coating method, etc., but the dipping method is the best in the case of a cylindrical support. This is a method to obtain a coating film on the support by immersing the support in a coating solution and then pulling it up at a predetermined speed, allowing precise control of film thickness using relatively simple equipment. It is. To produce the above-mentioned two-layer structure photoreceptor using this method, first, a charge generation layer is formed by dipping a cylindrical support in a coating solution for one generation generation layer, pulling it up, and drying it. By pulling up the support on which the charge generation layer is formed in the hole-transporting charge transporting layer coating solution at a predetermined speed and drying it, a charge transporting layer is formed, and the desired photoreceptor can be obtained. .

Therefore, regardless of whether the photoreceptor is a single-layer photoreceptor or a two-layer photoreceptor, the uppermost layer is a photoconductive layer made of a thermoplastic resin containing a charge transport material, and if necessary a charge generation material as a binder resin. .

[Problem to be solved by the invention]

Electrophotographic materials are required to have the desired sensitivity, feel, and optical properties according to the electrophotographic process to which they are applied, and are also desirable to have good moisture resistance and durability. It will be done. However, as mentioned above, since organic photoreceptors use resin as a binder, their surface hardness is lower than that of photoreceptors. There is speculation that when manipulated with a nylon brush or rubber blade, the surface wears down and the photoconductivity changes. In addition, due to frictional contact with the magnetic carrier used in the two-component developer, changes in photoconductivity due to surface abrasion are also likely to occur.

Therefore, the biggest drawback of organic photoreceptors is their durability, with a printing durability of 10,000 to 50,000 sheets, compared to 50,000 to 300,000 sheets for selenium-based photoreceptors and 500,000 to 1,000,000 sheets for amorphous silicon photoreceptors. Considering the application to medium-speed and high-speed copying machines and original printers, there was a need for even higher printing durability.

[Means to solve problems]

A silicone resin composition having a weight average molecular weight of 103 to 106 obtained by hydrolyzing a mixture of methyltoIJ alkoxysilane of the following general formula (A) and tetraalkoxysilane of the following general formula (B) as a binder resin in υ can be solved by heat curing and using.

CH, S 1<OR+ )3 ・ ・ ・ (A
)8 i (0R2), ・・・
(B) However, L and Rt are CH, or C, ■I.

[Effect]

The photoconductive layer in the present invention refers to a photoconductive layer in a single-layer organic photoreceptor containing a charge-generating substance, or a charge-generating substance and a charge-transporting substance in a binder resin. moreover,
In a two-layer organic photoreceptor in which a charge generation layer and a charge transport layer are sequentially provided on a conductive support, it refers to a charge transport layer containing a charge transport substance in a binder resin. It also means a charge generation layer containing a charge generation substance in a binder resin in a laminated organic photoreceptor in which a charge transport layer and a charge generation layer are sequentially provided on a conductive support.

The noricone resin composition of the present invention has a weight average molecular weight of 1. O
An organic nolicone polymer soluble in organic solvents having an OQ of ~1.000.000, with a preferred range of 1.000.
~100,000. 1N average molecular weight is 1.000
If it is less than that, the crosslinking density of the polymer after thermosetting becomes too high, and the film is likely to be cracked. On the other hand, if the weight average molecular weight is 1.000,000 or more, the crosslinking density becomes low, and a desirable value for the hardness of the cured product cannot be obtained. Furthermore, polysilsesquioxanes having relatively higher alkyl groups such as aryl groups such as noenyl groups and tolyl groups, or isoamyl groups and isoamyl groups are also known. Group-containing silicone resins have the disadvantage that they are easily decrystallized and cannot form a uniform film.

The silicone resin composition of the present invention is prepared by dissolving methyl) IJ alkoxy 7rane and tetraalkoxysilane in a solvent such as butersenolp, adding ion-converted water to hydrolyze, removing the aqueous layer using a dispersion funnel, and then dissolving the evaporate. By removing water, a high molecular weight silicone resin composition of a co-condensation polymer of methyltrialcoquine silane and tetraalkoxysilane is obtained. The mixing ratio of methyltrialcoquinolane and tetraalkoxysilane can be set arbitrarily, but is preferably equimolar.

According to the present invention, by using the silicone resin composition as a binder resin for the photoconductive layer, the surface hardness can be significantly increased compared to conventionally used thermoplastic resins2, and thus the electrophotographic process The photoconductive layer is not scraped or worn out even by the harsh cleaning conditions of the process or by repeated contact with a magnetic brush developing agent made of magnetic carriers, something that was thought to be impossible with conventional organic photoreceptors. It has a lifespan of 100,000 sheets or more and can provide excellent durability.

The photoconductive layer contains a charge-generating substance or It is formed by applying an earthwork liquid in which a charge generating substance and a charge transporting substance, or a charge transporting substance alone are dispersed and dissolved, onto a conductive support, a charge generating layer, or a charge transporting layer and drying it. As the charge generating substance, known ones can be used, for example,
Bisazo compounds, trisazo compounds, perylene compounds, indigo compounds, cyanine compounds, squarylium compounds, phthalocyanine compounds, and the like can be used. Furthermore, known charge transport materials can be used, such as hydrazone compounds, pyrazoline compounds, oxisazole compounds, and the like. Further, an undercoat layer can be provided between the conductive support and the photoconductive layer in order to improve adhesion, prevent thermal carrier injection, and the like. As the undercoat layer, resins such as polyvinyl alcohol, polyvinyl butyral, polyamide, and epoxy, or resins in which additives such as tin oxide, indium oxide, and titanium oxide are added to these resins are used.

Generally, the thickness of the charge transport layer is 5 to 30 .mu.m, the thickness of the charge generation layer is 0.01 to 3 .mu.m, preferably 1 .mu.m or less, and the thickness of the undercoat layer is 0.01 to 3 .mu.m.

Hereinafter, the present invention will be explained according to examples.

〔Example〕

Synthesis example: Dissolve 50 ml of methyltriethoxysilane and 50 ml of %tetraethoxy/ran in butyl cellosolve, add ion-exchanged water to hydrolyze, remove the aqueous layer using a separating funnel, and further dissolve with evaborate. By removing water, a butyl cellosolve solution of a cocondensation polymer of methyltriethoxysilane and tetraethoxysilane was obtained. The obtained resin solution was concentrated to obtain a 50 wt % silicone resin solution. As a result of GPC analysis, the weight average molecular weight was 3,000, and the ratio of weight average molecular weight to number average molecular weight was 1.4.

Example 1: Silicone resin obtained in synthesis example (solid content)
70 parts by weight, 30 parts by weight of C-type copper phthalocyanine, and 20 oxIi parts of butyl cellosolve were placed in a hard glass pot, and dispersed and mixed together with hard glass beads for 24 hours to obtain a coating liquid. Next, the coating solution was applied onto a 600 x 250 nm aluminum tube by a dipping method, and then heat treated at 120'Q for 60 minutes to fabricate a single-layer positively charged organic photoreceptor with a film thickness of about 20 μm.

Arrow measurements were performed on this Kangen body. First, corona charging is performed at 6 kV, and the surface potential after 1 second is set to VoCV). Then, the surface potential when dark decayed for 1 second is 1 (V),
From that moment, perform exposure at 780 nm and 10μ radiation, and find the time t1/ until the surface potential becomes half of VO.
Calculate the half-reduced no-light amount El,, <μJ7m). Furthermore, one process is completed by recording the surface potential Vr (V) at 10 t+/t after the start of exposure. Also 100xV+/vo
was calculated as the charge retention rate DI (%). The results obtained are shown in Table 1.

In order to evaluate the stability during repeated use, that is, durability, the photoreceptor produced in this example was printed for 100,000 sheets using Fujitsu Mv-Sublink M3722L, and the initial and 100,000 sheets were printed. The subsequent photoreceptor characteristics were compared. The results are shown in Table 1 in comparison with the initial results.

Table 1 As a result, it is clear that the photoreceptor of Example 1 shows almost no change in photoreceptor characteristics even after printing ioo and ooo, and has extremely excellent printing durability.

Example 2 50 parts by weight of S-type copper 7p C-J"2 and 50 parts by weight of polyester resin were dissolved in tetrahydrofuran and put into a hard glass pot together with hard glass beads.
The charge generation layer coating solution was prepared by time-dispersed mixing. As in Example 1, the coating solution was applied onto a 59p x 250mm aluminum tube using the dipping method, and then heat treated at 120'0 for 60 minutes.
A charge generation layer having a thickness of about 0.5 μm was formed.

Fifty parts by weight of the hydrazone compound and 50 parts by weight of the silicone resin (solid content) obtained in the synthesis example were completely dissolved in one methyl ethyl ketone. The aluminum support coated with the charge generation layer was coated with this coating solution by dipping/bowing method, and heated and cured to form a charge transport layer with a thickness of approximately 20 μm. We prototyped a layered organic photoreceptor.

5. The photoconductor characteristics of this photoconductor were evaluated in the same manner as in Example 1, and furthermore, in order to evaluate the stability and durability during repeated use, Fujitsu Laser Printer M37
100,000 sheets were printed using a 22L laser printer whose charge polarity, transfer polarity, etc. had been modified to use a negative band photoreceptor, and the photoreceptor characteristics at the initial stage and after printing 100,000 sheets were compared. Note that corona charging was set at -6 kV.

The results are shown in Table 2. Based on this conclusion, the photoreceptor of Example 2 has 10
It is clear that there is almost no change in the photoreceptor characteristics even after 0,000 printings, and that the printing durability is extremely excellent.

In the case of a photoreceptor having a laminated structure, the uppermost layer may be used as a charge generation layer.

〔Effect of the invention〕

In this manner, the photoreceptor of the present invention can achieve durability and printing durability that were unachievable with conventional organic photoreceptors.

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor having a photoconductive layer consisting of a photoconductive material and a binder on a conductive support, methyltrialkoxysilane of the following general formula (A) and the following general formula (B) are used as a binder resin. ) obtained by hydrolyzing a mixture of tetraalkoxysilanes with a weight average molecular weight of 10^3 to 10^6
1. An electrophotographic photoreceptor characterized in that the silicone resin composition is thermally cured. CH_3Si(OR_1)_3...(A) Si(OR_2)_4...(B) However, R_1 and R_2 are CH_3 or C_2H_5 (2) The electrophotographic photoreceptor according to claim 1, wherein the photoconductive layer contains a charge generating substance, a charge generating substance and a charge transporting substance, or a charge transporting substance in a binder resin.