JPH0345958A - Electrophotographic sensitive body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a fluorine-substituted paraffinic block copolymer in the photosensitive layer.

[Prior art 1] The surface of an electrophotographic photoreceptor is subjected to various processes in an electrophotographic copying machine, such as corona charging, toner development, transfer to paper, etc.
They are directly subjected to electrical, thermal, and even mechanical external forces such as cleaning processes.

Therefore, in order to use the photoreceptor repeatedly, it is important that the surface layer has strong durability against these treatments. In particular, durability against surface damage caused by cleaning is an important item.

On the other hand, the first surface layer contains residual toner after transfer.

Paper dust from the transfer paper and decomposition products caused by ozone generated by corona charging will adhere, so if the cleaning process is insufficient, residual toner will fuse to the surface layer and reduce surface resistance, resulting in poor image quality. This is the cause of the decline.

That is, image blurring occurs due to adhesion of low-resistance substances and image blurring occurs due to lower resistance of the surface layer. Furthermore, there are problems such as scratches and wear caused by external mechanical forces.

Therefore, in order to satisfy repeated durability, it is necessary that the surface layer of the photosensitive couple has good leaning performance, that is, durability and slip properties.

Conventionally, attempts have been made to meet these demands by adding substances that impart lubricity to the surface layer. Such substances include common coating surface modifiers, i.e.
There are leveling agents, silicone oil, etc.

Another method is to disperse Teflon powder.

However, general surface modifiers have poor compatibility with the components of the coating liquid to which they are added, so they tend to ooze out onto the surface layer during long-term use, making it difficult to maintain their effects. there were.

In addition, when the surface layer itself forms a photoconductive layer, the surface modifier has poor compatibility with the photoconductive substance and tends to act as a trap for the movement of carriers due to photogeneration, and remains after repeated electrophotographic processes. There was a tendency for the charge to increase.

On the other hand, a surface layer in which Teflon powder or the like is dispersed has problems such as poor dispersibility, decreased transparency, and carrier trapping.

[Problems to be Solved by the Invention 8J The purpose of the present invention is to eliminate the above-mentioned drawbacks, maintain excellent electrophotographic properties, and furthermore have a surface layer with excellent lubricity on the surface and good cleaning properties. To provide an electrophotographic photoreceptor that has excellent repeat durability and less damage to the surface layer; and an electrophotographic photoreceptor that does not accumulate residual charge in repeated electrophotographic processes and always provides high-quality images. To provide a photoreceptor 1. It is an object of the present invention to provide a high quality electrophotographic photoreceptor that does not suffer from image blurring or image deletion due to paper dust or ozone decomposition products.

[Means for Solving the Problems, Effects J] As a result of repeated research aimed at achieving the above object, the present inventors have discovered a fluorinated paraffin that is soluble in aromatic hydrocarbon solvents or halogenated aromatic hydrocarbon solvents. The inventors have discovered that the above-mentioned problems can be solved by using block copolymers, and have arrived at the present invention.

The present invention comprises an electrophotographic photoreceptor having a conductive support and a photosensitive layer, wherein the photosensitive layer contains a fluorine-substituted paraffinic block copolymer.

The fluorine-substituted paraffinic block copolymer used in the present invention consists of a trunk segment and a branch segment,
It is a functional block copolymer that can simultaneously express the properties of each segment without impairing each other.

The above-mentioned fluorine-substituted paraffin block copolymer has a trunk segment of a methacrylic polymer, an acrylic polymer, a vinyl acetate polymer, a styrene polymer, a polycarbonate polymer, or a polyester polymer, and the branch segments are a fluorine-substituted paraffin polymer. Fluorine-substituted paraffinic block copolymers are synthesized by radical polymerization, and unlike conventional random polymers produced by ionic polymerization, in which it is difficult to selectively select functions, they have great functional effects.

That is, in the present invention, a fluorine-substituted paraffin polymer is selected as a branch segment that mainly has an effect on lubricity, and is used in the photosensitive layer of an electrophotographic photoreceptor to improve the slipperiness, abrasion resistance, and water repellency of the photoreceptor surface. , it was possible to improve oil repellency.

Fluorine used in the present invention! The paraffinic block copolymer will be specifically explained.

The fluorine-substituted paraffinic block copolymer is composed of a combination of a trunk segment polymer (hereinafter referred to as A) and a branch segment polymer (hereinafter referred to as B) that mainly exhibits functions.

The combinations of A and B are A-B and A-B-A.

A-B-A-B and the like are arbitrary, and the ratio is not particularly limited.

Typical specific examples of A and B will be listed below, but the present invention is not limited thereto.

Examples of the methacrylic polymer A include polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polyhexyl methacrylate, polydecyl octyl methacrylate, and polystearyl methacrylate.

Acrylic polymers include polymethyl acrylate,
Examples include polyethyl acrylate, polybutyl acrylate, poly-2-ethylhexyl methacrylate, and polymethoxyethyl acrylate.

Examples of the vinyl acetate polymer include polyvinyl acetate and a copolymer of vinyl acetate and ethylene.

Styrenic polymers include polystyrene, chloromethylated polystyrene, styrene-butadiene copolymer,
Examples include styrene-methacrylate copolymer.

Typical examples of polycarbonate polymers are listed below.

Polycarbonate polymer structural formula (1) Polycarbonate polymer structural formula (2) Polycarbonate polymer structural formula (3) Polycarbonate polymer structural formula (4) Polycarbonate polymer structural formula (5) % formula% ) Polycarbonate polymer structural formula (7) Typical examples of polyester polymers include unsaturated polyesters that are free from styrene, leic acid, ethylene glycol, and phthalic acid, and alkyd resins that are safe from phthalic acid and glycol. It will be done.

As B, a fluorine-substituted paraffin polymer is used.

Typical examples include polyvinylidene fluoride, polyvinyl fluoride, ethylene-tetrafluorinated ethylene copolymer, tetrafluoroethylene-hexafluoropylene copolymer, and the like.

The number average molecular weight of the block copolymer consisting of the combination of A and B is 5,000 to 10,000,000, more preferably 10,000 to 5,000,000, especially 2
10,000 to 1 million is preferable.

In addition, the content of A in the block copolymer is 5 to 9.
0% by weight is preferred, more preferably 10-80% by weight, especially 30-70% by weight.

The fluorine-substituted paraffinic block copolymer used in the present invention is used in the surface layer of the photoreceptor in order to improve the slipperiness and abrasion resistance of the surface of the photoreceptor.

In the case of a laminated photoconductor (41-layer separation type photoconductor).

It is contained in the charge generation layer or charge transport layer.

In the present invention, the fluorine-substituted paraffinic block copolymer is used as a phase with a coating liquid containing a charge-generating material and a binder resin if the layer contained is a charge-generating layer, or with a coating liquid containing a charge-transporting material if it is a charge-transporting layer. Must have excellent solubility.

In the fluorine-substituted paraffinic block copolymer of the present invention, the branch segment (B), which has the function of improving water repellency, oil repellency, and stickiness, tends to be localized near the surface, resulting in improved lubricity and lubricity of the photoreceptor surface layer. Increased abrasion resistance and exhibits good leaning properties.

Therefore, residual toner on the surface layer of the photoreceptor after transfer, paper dust from the transfer paper, and decomposition products caused by ozone generated by corona charging are effectively removed by cleaning.
Because it is hard to scratch, potential stability and image quality stability during repeated durability are distantly related.

When producing the electrophotographic photoreceptor of the present invention, the conductive support may be a metal such as aluminum or stainless steel, or an alloy 1.
Cylindrical cylinders or films of paper, plastic, etc. are used.

A subbing layer (adhesive layer) having a barrier function and an undercoat function can be formed on these supports.

The undercoat layer improves the adhesion and coating properties of the photosensitive layer.

It is formed for purposes such as protecting the support, covering defects on the support, improving charge injection from the support, and protecting the photosensitive layer from electrical breakdown.

The material for the undercoat layer is polyvinyl alcohol poly-N.
-vinylimidazole, polyethyleneoxide, ethylcellulose, methylcellulose.

Known examples include ethylene-acrylic acid copolymer, casein, polyamide, copolymerized nylon, glue, and gelatin. These materials are each dissolved in a suitable solvent and applied onto the support.

The film thickness is about 0.2 to 2 gm.

In the functionally separated photoreceptor, selenium, selenium-tellurium, pyrylium dye, thiapyrylium dye, phthalocyanine pigment, anthoanthrone pigment,
Dibenzpyrenequinone pigment, vilanthrone pigment, azo pigment, indigo pigment, quinacridone pigment, asymmetric quinocyanine, quinocyanine or JP-A-143-1989
Amorphous silicon described in Japanese Patent Publication No. 645 can be used, and charge transport materials include pyrene N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-7enylhydrazino-3-methylidene-9-
Ethylcarbazole, N,N-diphenylhydrazino-
3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-1O-ethylphenothiazine, N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde N , N-diphenylhydrazone, p-diethylaminostyryldehyde, do-N-α-naphthyl-N-phenylhydrotezone 2 p-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1,
3.3-trimethylindolenine-ω-aldehyde-N
, N-diphenylhydrazone, hydrazone compounds such as P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2.5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, l-7enyl-3-(p-diethylaminostyryl)
-5-(p-diethylaminophenyl)pyrazoline, 1
-[quinolyl(2)]-3-(p-diethyl7minostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α-methyl-p
-diethylaminostyryl)-5-(p-diethylaminophenyl)hirazoline, 1-phenyl-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(α-benzyl-p-diethylaminostyryl)-5-
Pyrazoline compounds such as (p-diethylaminophenyl)pyrazoline and spiropyrazoline, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(
Oxazole compounds such as p-dimethylaminophenyl)5-(2-chlorophenyl)oxazole, 2-(
Thiazole compounds such as p-diethylaminostyryl)-6-dinithylaminobenzothiazole, bis(4-
Triarylmethane compounds such as diethylamino-2-methylphenyl)-phenylmethane, 1. l-bis(
4-N,N-diethylamino-2-methylphenyl)hebutane, 1,1,2.2-tetrakis-(4-N,N-
A polyarylalkane compound such as dimethylamino-2-methylphenyl)ethane can be used.

The charge generation layer is prepared by thoroughly dispersing the above charge generation substance together with 0.3 to 4 times the amount of binder resin and a solvent using a method such as a homogenizer, ultrasonic wave, ball mill, vibrating ball mill sand mill, attritor, roll mill, etc. to form a dispersion. Formed by coating and drying. The film thickness is 0.1~1JLm
That's about it.

Known coating methods include, for example, a dip coating method, a spray coach ink method, a spinner coating method, and a curtain coating method. Dip coating is the best way to mass-produce electrophotographic photoreceptors efficiently and accurately, and in particular, the pot life in dip coating can be greatly improved by using the aforementioned polycarbonate. The productivity of manufacturing using this method can be significantly improved.

After coating and forming the charge transport layer coating liquid, the temperature is 10 to 200°C.
, preferably at a temperature of 20-150°C for 5 minutes to 5 hours,
Air blow drying or stationary drying is preferably performed for 10 minutes to 2 hours to form a charge transport layer with a thickness of 5 to 20 μm.

In this way, an electrophotographic photoreceptor is produced.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in a wide range of electrophotographic applications such as laser beam printers, CRT printers, and electrophotographic plate making systems.

[Example] The wear characteristics and contact angle of the surface layer described in the following examples were measured under the following conditions.

(a) Abrasion characteristics Measurement device using taper tester: Taper abrasion tester Measurement conditions Sample preparation: Coat the resin solution on an aluminum disk and dry it.
A coating film with a thickness of around 0 gm is used.

Grinding wheel model number: CS l 7 Load: t, 000g Rotation speed near 0 rpm Total number of rotations: 5,000 rotations Measurement environment: Temperature 23 ± 1°C Humidity 55 ± 5% RH (b) Molecular weight by gel permeation chromatography (GPC) Measuring device: Waters High Performance Liquid Chromatograph 244 Column: Toyo Soda ■ GMH Standard material: Toyo Soda ■ Standard polystyrene Maximum molecular weight 448 x 10" Measurement conditions Sample preparation Niblock copolymer Long/tetrahydrofuran 4 m injection amount = 200 m Solvent: tetrahydrofuran flow rate : 1 mJl/min Temperature = 23 ± 1"0 Detector: Differential refractometer (e) Contact angle Measuring device by contact angle: Kyowa Scientific ■ Contact angle meter CA-DS measurement conditions Sample preparation: Same coating as for wear characteristic measurement Evaluation method using a film formed: Temperature at which the contact angle of the coating film with water was measured by a droplet method: 23±1"c Example 1 A 60 x 260 mm aluminum cylinder was used as a conductive support.

On top of this, polyamide (trade name Amilan CM-8000,
Apply a 5% methanol solution (manufactured by Toshi ■) by dipping method, and
．． A subbing layer with a thickness of 51 parts m was provided.

Next, 10 parts (by weight, the same applies hereinafter) of a disazo pigment with the following structure, polyvinyl butyral (trade name: SLEK BXL)
, manufactured by Mizu Kagaku ■) and 50 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using 1φ glass beads.

Add 70 to 120 methyl ethyl ketone (as appropriate) to this dispersion.
0.15 parts m thick and coated on the undercoat layer.
A charge generation layer was formed.

Next, 10 parts of a hydrazone compound having the following structure, 10 parts of a block copolymer consisting of 2 polymethyl acrylate and polyvinylidene fluoride (50:50) were dissolved in 35 parts of chlorobenzene and 20 parts of dichloromethane.

This solution was applied onto the charge generation layer by dip coating and dried with hot air at 120° C. for 60 minutes to form a charge transport layer having a thickness of 18 parts m.

The prepared electrophotographic photoreceptor was corona charged at -5,6KV 1
It was installed in an electrophotographic copying machine that has image exposure, dry toner development, plain paper toner transfer, and cleaning steps using a rubber blade, and the durability of the image was evaluated in an environment of 25° C. and 50% RH.

Furthermore, the abrasion characteristics and contact angle molecular weight of this electrophotographic photoreceptor were measured. The results will be described later.

Examples 2 to 5 Electrophotographic photoreceptors in Examples 2 to 5 were prepared in the same manner as in Example 1, except that the block polymer in the charge transport layer in Example 1 was changed.

Each electrophotographic photoreceptor was evaluated in the same manner as in Example 1. The results will be described later.

Comparative Examples 1 to 3 Electrophotographic photoreceptors in Comparative Examples 1 to 3 were prepared in the same manner as in Example 1, except that a single polymer was used instead of the block copolymer in Example 1.

Each electrophotographic photoreceptor was evaluated in the same manner as in Example 1. Show the results.

Surface layer Example 1 Trunk segment A: Polymethyl acrylate Branch segment B: Polyvinylidene fluoride A/B: 50150 Number average molecular weight: 12,000 Example 2 Trunk segment A: Polymethyl methacrylate Branch segment B: Polyvinylidene fluoride A/B B: 40/60 Number average molecular weight: 15,000 Example 3 Trunk segment A: Polyvinyl acetate Branch segment B: Polyfluorinated vinyl A/B: 70/30 Example 4 Trunk segment A: Polystyrene Branch segment B: Polyfluorinated Vinyl A/B: 70/30 Number average molecular weight: 20.000 Example 5 Trunk segment A: Polycarbonate Structural formula (2) Branch segment B: Polyfu Vinylidene dihydride A/B: 6
0/40 Number average molecular weight: 13,000 Comparative example 1 Polymethyl acrylate number average molecular weight: lO,000 Comparative example 2 Polymethyl methacrylate number average molecular weight: 13,000 Comparative example 3 Polystyrene number average molecular weight: 15,000 4.7 Xl0-" 105° 4.5 Xl0-"10G' 3.8 Xl0-"110' 3.8 XIG-" 88° 4.2 5,000 good images: 5,000 good images: 5,000 good images: 5,000 good images: Good image repeatability Image stability Note that the image evaluation is based on the results of visually observing the copied images.

From the above results, when the single polymer of the comparative example is used for the charge transport layer, it has low abrasion resistance, so scratches occur on the surface due to durability, and black streaks appear on the image. Because the contact angle is low, paper dust and ozone decomposition products generated by corona charging tend to adhere, which tends to cause image blurring or image deletion.

In contrast, examples using fluorine-substituted paraffinic block copolymers have high abrasion resistance and a large contact angle, so they are less likely to cause scratches on the electrophotographic photoreceptor, and because of the lubricious holes, they are less likely to cause scratches. Shows linting properties.

Furthermore, there is no image quality deterioration such as image blurring or image deletion that is observed in the electrophotographic photoreceptor of the comparative example.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention contains a fluorine-substituted paraffin block copolymer in the photosensitive layer, thereby eliminating image quality deterioration due to image blurring or image deletion, and exhibiting excellent surface slipperiness and cleaning properties. Excellent repeated durability
This has the remarkable effect that there is little damage to the surface layer and good image quality can always be obtained.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a conductive support and a photosensitive layer, wherein the photosensitive layer contains a fluorine-substituted paraffinic block copolymer. 2. As a fluorine-substituted paraffinic block copolymer, the trunk segment is a methacrylic polymer, an acrylic polymer, a vinyl acetate polymer, a styrene polymer,
2. The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is a polycarbonate polymer or a polyester polymer, and the branch segment is a fluorine-substituted paraffin polymer. 3. The branch segment is a fluorinated paraffinic polymer selected from the group consisting of polyvinylidene fluoride, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymer and tetrafluoroethylene-hexafluoropropylene copolymer. Electrophotographic photoreceptor. 4. The photosensitive layer has a laminated structure including a charge generation layer and a charge transport layer, and at least one layer of the charge generation layer and the charge transport layer contains a fluorine-substituted paraffin block copolymer. 1. The electrophotographic photoreceptor according to 1.