JPS63199359A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance mechanical strength of a photosensitive body and to improve an image by using a specified copolymer for the binder resin of a photosensitive layer. CONSTITUTION:The copolymer is made from at least four kinds of the following monomers: (A) methacrylate, preferably such as methyl and/or ethyl methacrylate, (B) acrylate, preferably such as butyl and/or methyl acrylate, (C) an organic acid capable of radical polymerization, such as (meth)acrylic acid or itaconic acid, and (D) (meth)acrylate having an epoxy group, and it is preferred to add a photoconductive pigment, such as zinc oxide, to the photosensitive layer in an amount of 60-90wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor used in an Enoki photocopier, a printer, or the like.

[Conventional technology]

There have traditionally been many types of electrophotographic photoreceptors, such as selenium, amorphous silicon, and cadmium sulfide/resin systems, but photoconductive pigments and resin binders on a conductive substrate? An electrophotographic photoreceptor having a photosensitive layer containing a photoreceptor can be manufactured by coating, has the possibility of cost reduction, and is widely used.

As a resin binder applied to the photosensitive layer of such an electrophotographic photoreceptor, the material is easy to handle, and copolymerization is easy, so a resin suitable for the purpose can be obtained relatively easily. , etc., acrylic resins are often used. The resin inder constituting the photosensitive layer of the electrophotographic photoreceptor of the present invention also belongs to the acrylic resin. Acrylic resin is a copolymer of hard components such as methyl methacrylate-1, ethyl methacrylate, and styrene, and soft components such as n-butyl acrylate, imbutyl acrylate, 2-ethylhexyl acrylate, and n-octyl methacrylate. Combination is used to help.

Does the hard component improve mechanical strength and charging potential? However, on the other hand, the residual potential becomes high.1. Curling properties tend to increase and adhesion properties tend to decrease. Furthermore, although the soft component contributes to improving flexibility, photosensitivity, residual potential, etc., it tends to deteriorate the mechanical strength of the photoreceptor. Therefore, Aku I
J) Photoreceptors with good resin photosensitive layers tended to have poor mechanical strength. Sometimes, when the photoconductive pigment is zinc oxide, the zinc oxide content is 60% or more. As this is common, it is susceptible to scratches, resulting in background smudges and poor solid density.Especially, photoreceptors for offset printing plates are required to be oil-sensitive, so they often contain soft components, so this tendency occurs. In order to solve this defect 2, Japanese Patent Publication No. 55-6217 and Japanese Patent Application Laid-Open No. 59-40654 have introduced large particles of zinc oxide with a diameter of 30 to 50 μm, or some kind of zinc oxide, in addition to fine particles of zinc oxide. Zinc oxide particles coated with resin were mixed in to form protrusions on the surface of the photoreceptor, so that frictional resistance was applied selectively to the protrusions, thereby preventing abrasion of the photosensitive layer itself and preventing background smearing and image blurring. A photoreceptor has been proposed. However, in this method, large protrusions of several tens to 100 μm exist on the surface of the photoreceptor.
It was impossible to reproduce fine patterns of m or less.

Further, JP-A-58-127932 discloses a photoreceptor in which a binder resin is made into a photocurable type and the mechanical strength of the surface is improved by irradiation with light after coating. However, since photoconductive pigments (ingu resin) absorb light that hardens the entire photosensitive layer, a powerful light source is required to cure the entire photosensitive layer, which not only increases the number of steps but also There was a tendency for the inner part to harden and become unhardened, making it difficult to obtain sufficient mechanical strength.Also, if unhardened parts remained,
Stability over time was also an issue.

Furthermore, JP-A-54-147838 discloses a photoreceptor in which a (meth)acrylic resin and an epoxy resin are blended to make a (J11) binder. However, since this is a blend, photoconductive pigment and The range of choices was narrow due to the mutual phase G properties of each resin.

Also, is it a #S conductive pigment or a phthalocyanine pigment? If the resin content is high, such as when used alone, there is no problem with the poem, or if zinc oxide, etc. However, since the components of the resin to be cured were limited by the blend, the mechanical strength was insufficient.

[Purpose of the invention]

The present inventors focused on the composition of electrophotographic photoreceptors in order to eliminate the above-mentioned drawbacks, and as a result of intensive research, they arrived at the present invention.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic α photoreceptor that has high mechanical strength and provides good image acquisition.

[Summary of the invention]

That is, the present invention provides at least a photoconductive pigment and a binder resin on a conductive support. Photosensitivity as a component 1jd
In an electrophotographic photoreceptor having Y, at least 4 of the following are selected from the group consisting of a 1-yonder resin, a methacrylic ester, an acrylic ester, a radically polymerizable organic acid, and an epoxy group-containing (meth)acrylic ester.
Is it a copolymer consisting of different types of monomers? This is a characteristic electrophotographic photoreceptor.

[Detailed description of the invention]

The present invention will be explained in detail below.

The torme-conducting supporting layer used in the present invention is made of aluminum, chromium, palladium, metal oxide, etc., which is vacuum-deposited on a metal plate such as aluminum, brass, copper, or stainless steel, or a metal sheet, or a plastic sheet. It is possible to use materials such as plastic plates, specially treated paper, and metal oxide plates or sheets.

As photoconductive pigments, zinc oxide, zinc sulfide, titanium oxide, cadmium sulfide, phthalocyanines represented by copper phthalocyanine, various bisazo pigments, and the like can be used alone or in combination.

Photoconductive pigments that are spectrally sensitized by dyes can also be used.On the other hand, resin binders include methacrylic esters, acrylic esters, radically polymerizable polyhydric acids, and (meth)acrylates containing epoxy groups. Use copolymer 2 containing at least an acid ester.

Examples of methacrylic acid esters that can be used include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, 1-propyl methacrylate, n-butyl methacrylate, and m-t-butyl methacrylate. Methyl methacrylate and ethyl methacrylate are preferred because they have excellent retention power. These methacrylic acid esters may be used alone or in combination, but if the content is too high, it will become brittle, and if it is too low, the mechanical strength will deteriorate, so 20 wt% to 70 wt% is preferable.

Examples of acrylic esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, 1-propyl acrylate, n-butyl acrylate, 1-butyl acrylate, 1-butyl acrylate, and acrylic acid. Pentyl acrylate, 2-ethylhexyl acrylate, etc. are exemplified, but methyl acrylate, full-n-butyl acrylate, and 2-ethylhexyl acrylate have excellent adhesion to the substrate and moderate flexibility. preferred for showing. Methyl acrylate, acrylic (1/1-n-butyl,
It is preferable because it not only has excellent electrophotographic properties but also excellent wet developability. These acrylic acid esters are used alone or in combination, but if the content is too high, the mechanical strength will be insufficient, and if the content is too low, the flexibility will be insufficient, so 560 to 70 wt% is preferable. , crotonic acid, cinnamic acid, maleic acid, etc. If the content is too high, the dark resistance will decrease and it will become difficult to charge, and if the content is too low, there will be no effect.
wt% is applied, preferably between 2 and 10 wt%.

Epoxy group? Examples of the (meth)acrylic esters include glycidyl (meth)acrylate, epoxystearyl (meth)acrylate, (6,4 epoxycyclohexyl)ethyl (meth)acrylate, glycidoxy (meth)acrylate, and the like. The content is 1 to 20 wt%, preferably 2 to 10 wt%. This is because if the amount is too large, the stability of the coating liquid will be poor, and if it is too small, there will be no effect.

To prepare this resin binder, the appropriate monomers are mixed with organic solvents such as aromatic hydrocarbons, ketones, and esters in the presence of an initiator such as zobisinbutyl nitrile or benzoyl peroxide. What is necessary is just to carry out solution polymerization using it. Suspension polymerization and solvent-free polymerization are also possible.

Further, the method for manufacturing the photoreceptor of the present invention includes dispersing the photoconductive pigment, binder resin, solvent, etc. using a ball mill, paint shaker, ultrasonic homogenizer, sand mill, etc., and dispersing the photoconductive pigment onto a conductive substrate using an applicator, spray coater, /
<-A method of applying and drying using a coater, tip coater, doctor bundle, etc. is suitable. For this one-time drying, it is preferable to heat the material with hot air of 100°C or higher for 40 seconds or more.

There are no particular restrictions on the composition, but the solid content of the photosensitive layer is 10 to 90 wt of photoconductive pigment and 8% binder resin.
~80 wt% is preferred.

In addition, when the photoconductor of the present invention is used as an electrofax machine, it is preferable to contain at least 2 zinc oxide as a photoconductive pigment from the viewpoint of printing suitability, and in this case, the content of the photoconductive pigment 4 is preferable. The amount is 60wt%~9
0*t% is required.

Forming the image 1j4Y using the electrophotographic image obtained in this way can be carried out by a normal electrophotographic method. In other words, after the surface of the electrophotographic photoreceptor is uniformly charged by corona discharge in a dark place, it is imagewise exposed to form an electrostatic latent image. toner? Adhere and perform transfer or fixing 2 as necessary.

[Function] The present invention uses methacrylic esters and acrylic esters with well-balanced electrophotographic properties as a resin binder, and also has a reactive epoxy group (meth).
Acrylic ester and radically polymerizable organic M2
Copolymerized resin? It is characterized by its use. In other words, a copolymer of methacrylic ester and acrylic ester with well-balanced electrophotographic properties is thermoplastic, and if left in a rolled or stacked state for a long time, it will plastically deform.
However, in the present invention, due to the presence of reactive groups, it hardens with /J [+ heat at the drying level during photoreceptor production, and does not deform with subsequent heat or pressure. . Furthermore, (meth)acrylic acid esters with epoxy groups and organic acids capable of radical polymerization do not only have a negative effect on electrophotographic properties, but also on image quality. It doesn't bring.

Furthermore, since it is a single copolymer rather than a blend of multiple resins, there is no need to worry about compatibility and a stable pigment dispersion system can be obtained. Furthermore, since the cross-linking reaction of epoxy is a ring-opening reaction, there is no volume contraction, and there are no curls or cracks caused by cross-linking. Furthermore, the presence of an appropriate amount of polar component improves the dispersibility of the pigment. Furthermore, since the mechanical strength is improved not by surface irregularities but by the hardness of the binder resin itself, the reproducibility of fine lines is further improved and the quality of the reproduced image is good.

〔Example〕

The present invention will be explained in detail below with reference to Examples.

(Example 1) Table 1 Tetraiodofluorescein 1.5.97 was dissolved in 800 g of methanol, and 80 g of zinc oxide (5NSEX2000 manufactured by Sakai Chemical Co., Ltd.) was added * using an ultrasonic homogenizer manufactured by Nippon Seiki Seisakusho Co., Ltd. After dispersing for 10 minutes with
Methanol was evaporated at 0° C. to obtain 80 g of spectrally sensitized zinc oxide.

Resin binder, @liquid, spectrally sensitized zinc oxide, seron acetate 40g each, aog, 300g725
Place 0cc in a glass bottle with 120g of glass beads and disperse for 60 minutes in a paint shaker (manufactured by Nnododevil Co., Ltd.). A water-soluble acrylic resin was coated as a water-soluble acrylic resin, and the coating solution was further coated so that the dry film thickness was 10 μrfL to obtain an electrophotographic photoreceptor. Characteristics were measured.

5 with the fabricated Naruko photographic photoreceptor Kaoru blocking tester
．． After pressing the front surface and the back side of the paper into contact with a pressure of 0 kg/t, i, and leaving it for 24 hours in an environment of 60° C1s o Ri-I%, there was no change in the surface. Observed.

In addition, by overlapping the front and back sides of the electrophotographic photoreceptor, Ryobi printing, Isosha light offset printing Iso AD-8
The device was installed on a 00 plate cylinder, and the surface of the electrophotographic photoreceptor was observed by rotating it 50 times under the pressure of the plate and blanket.

Further, an electrophotographic photoreceptor was prepared as described above using a plate making machine PM40 manufactured by Iwasaki Tsushin Co., Ltd. Is it used for plate making? Action 5
Illl1l print with Ryobi AD-80, what is the image quality? compared. Is there a commercially available offset master for reference? 2 printings were carried out using

The above describes the electrophotographic characteristics, the pressure bonding test, the forced rubbing test using Printing Surface 2, and the image quality evaluation of printed matter.

The electrophotographic characteristics were measured using Kawaguchi Electric's Static 1? The corona potential was -5kV, and the exposure was 2μvV/
・I used Go's tungsten light. ■ 0 is the maximum value of the measured surface center position, E1/2 is the dew # after this 1 second, the likely energy density required for the surface potential to drop to 1/2 after the start of the finger, D1/ 2 is the time required for ■0 to drop to 1/2 in the dark and Φ, and Dres is 10 times the likelihood energy of E1/2? It was the Ichii position at the time of giving.Φ.

112) ε-type copper phthalocyanine Heliog as a photoconductive pigment
en Blue L670OF (manufactured by BASF)? Samples A1 and JF described in (Example 1) were used as resin binders, and the proportions were 60 g of resin binder jf, 70 g of ε-type trunk phthalocyanine Y, and 30 g of selon acetate.
Electrophotographic photoreceptors (Zamburuya 1', A2
')'; i was created.

In addition, a forced rubbing test 2 was conducted using the same method as in Example 1 to test the image quality and pressure bonding, and the results are shown in Table 3.

Table 3 Measurements were carried out in the same manner as in Example 1 except that the corona potential was +6 kV.

[Effects of the Invention] As described above, the present invention improves mechanical strength by providing the unevenness 2 on the surface of the photoreceptor. The mechanical strength of the photoconductor itself is increased, rather than increasing the strength of the photoreceptor itself, resulting in extremely good image f'
J is beaten. Furthermore, since the binder resin itself is cured by heat, sufficient mechanical strength can be obtained by heating the coating device to the extent of drying. Furthermore, since it is thermally cured, the curing is uniformly distributed in the thickness direction of the photoreceptor layer, and no additional reaction occurs over time.

In addition, the electrophotographic properties themselves are determined by methacrylic esters and acrylic esters, and epoxy groups? The (meth)acrylic acid ester contained and the radically polymerizable organic compound have electrophotographic properties. In order not to give, l! III quality is good. Also, the curl increase 7Il]+ could not be achieved.

Further, the binder resin of the present invention can be applied to both N and p/P type photoconductive pigments.

Claims (1)

[Scope of Claims] 1) An electrophotographic photoreceptor having a photosensitive layer containing at least a photoconductive pigment and a binder resin on a conductive support, wherein the binder resin is a methacrylic ester, an acrylic ester, or a radical polymerized 1. An electrophotographic photoreceptor characterized in that it is a copolymer comprising at least four types of monomers: an organic acid and a (meth)acrylic acid ester having an epoxy group. 2) The electrophotographic photoreceptor according to claim 1, wherein the methacrylic acid ester is methyl methacrylate and/or ethyl methacrylate. 3) Acrylic ester is butyl acrylate or/
and methyl acrylate, the electrophotographic photoreceptor according to claim 1 or 2, wherein the electrophotographic photoreceptor is methyl acrylate. 4) Claims 1, 2, and 3, characterized in that the photoconductive pigment is contained in the photosensitive layer in an amount of 60 to 90 wt%.
The electrophotographic photoreceptor described in any of the above. 5) Claims 1, 2, and 3 contain at least zinc oxide as a photoconductive pigment.
The electrophotographic photoreceptor according to any one of Items 1 and 4.