JPH0333752A - Image holding member - Google Patents

Abstract

PURPOSE:To improve cleanability and repetitive durability by providing >=2 layers contg. a graft polymer having a polymerizable monomer having silicon atoms in the side chain as a conshituting component on the layer furthest from a conductive base. CONSTITUTION:At least >=2 layers 5, 6 from the layer side furthest from the conductive base 4 of the image holding member have he layer contg. the graft polymer having the polymerizable monomer contg. the silicon atoms in the side chain as the constituting component to constitute this image holding member. The image holding member having the surface layer which is transparent, is excellent in the lubricity and release property of the surface and excellent cleanability is, therefore, obtd. The excellent repetitive duarbility is obtd. and the damages of the surface layer are decreased.

Description

[Detailed description of the invention] [Industrial applicability! ? ] Is the present invention static? This invention relates to four types of image holding members for holding li images or toner images.

BACKGROUND OF THE INVENTION Electrostatic or toner images are formed by various electrophotographic processes. Image holding members that hold formed images include image holding members that have a photoconductive layer and are called electrophotographic photoreceptors, and image holding members that do not have a light guiding member.

Electrophotographic photoreceptors take various configurations depending on the type of electrophotographic process to which they are applied.

Typical electrophotographic photoreceptors include photoreceptors in which a photoconductive layer is formed on a support, and photoreceptors in which a photoconductive layer and its insulating layer are laminated as an image-retaining layer, and are widely used. ing.

A predetermined electrophotographic process is applied to the electrophotographic photoreceptor to form an electrostatic image, and this electrostatic image is developed and visualized. Therefore, the surface layer of such an image holding member is subjected to various treatments in an electrophotographic process, such as electromechanical treatments such as charging, exposure, development, transfer, and releaning.

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, in addition to the residual toner after transfer, paper dust from the transfer paper and decomposition products caused by ozone generated by corona charging adhere to the first surface layer, so if the cleaning process is insufficient, the residual toner will This causes adhesion to the layer and a decrease in surface resistance, thus causing deterioration of image quality.

Therefore, in order to satisfy the repeated durability, it is necessary that the surface layer of the image holding member has good leaning performance.

Furthermore, the following two methods are generally used for this cleaning.

The first method is to press a rubber plate-shaped member called a cleaning blade onto the photoconductor to close the gap between the photoconductor and the cleaning blade to prevent the toner from slipping through (1h L) and remove the remaining toner. This is a method of scraping it off.

0'! FIG. 1 is a 4I essential cross-sectional view showing a typical example of a cleaning device using such a leaning blade. Apply one edge of one end of the cleaning grade 3 attached to the cleaning device to the surface of the photoreceptor 2 in one direction counter to the rotating direction of the photoreceptor as shown in the figure, or in one direction (not shown). Scrape off the remaining toner by applying pressure in the forward direction (it is known that the cleaning performance is better in one direction of the counter).

The second method is to wipe or knock off the remaining toner by rotating the roller of the fur brush so that it comes into contact with the surface of the photoreceptor.

Of these two methods, since the rubber blade is cheaper and easier to design, cleaning using a cleaning blade is currently the mainstream.

In particular, when performing natural color development, magenta,
The three primary colors of cyan and yellow, or.

Furthermore, since natural colors are produced by overlaying four primary colors including black, the amount of toner used is much greater than in normal primary color development, which is why it is necessary to use a cleaning method that presses a rubber blade against the photoreceptor. suitable.

However, a cleaning blade that exhibits crushed cleaning properties has a drawback in that the cleaning blade tends to flip over because of the large frictional force with the photoreceptor.

This reversal of the cleaning blade means that the counter-unidirectional cleaning blade 3a shown in FIG. 1 is moved in the moving direction of the photoreceptor as shown by 3b.

This is a phenomenon in which the counter warps in the opposite direction.

What is the phenomenon of this cleaning blade turning over?

If the surface of the photoreceptor is made hard, that is, less likely to be scraped, in order to extend the life of the photoreceptor, this problem becomes even more likely to occur.

In addition, when toner particle size is made uniform and minute toner particles are removed to improve image quality, the lubricity caused by toner entering the gap between the cleaning blade and the photoreceptor surface is reduced. As it becomes thinner, the cleaning blade is more likely to flip over.

Furthermore, when performing natural color development, development is performed three or four times using toners of three colors, magenta, cyan, and yellow, or four colors, including black, to produce one image. For.

The load applied to the cleaning grade increases, making it more likely that the cleaning blade will reverse or even break at the edge.

In addition, when the surface layer of the photoreceptor is made of an organic substance, S
In particular, the frictional resistance between the cleaning blade and the photoreceptor surface increases compared to the surface of the machine material.

The cleaning blade is more likely to be reversed and the edge portion may be damaged.

Conventionally, as a measure to improve this phenomenon, attempts have been made to add a substance that imparts lubricity to one surface layer. Such substances include common coating surface modifiers,
That is, 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 migrate or ooze out onto the surface layer during long-term use, resulting in a lack of long-lasting effects. There was a problem.

Also, in JP-A-61-189559.

A method has been adopted in which the surface layer contains a graft polymer having as a component a polymerizable monomer having a silicon atom in its side chain, but in this case as well, the slipperiness of the surface of the photoreceptor lacks sustainability and is repeatedly When used for durability, the frictional force between the cleaning blade and the cleaning blade increased, causing the cleaning blade to turn over and the edge to break.

[Problems to be Solved by the Invention] An object of the present invention is to provide an image holding member having a surface layer that is transparent, has excellent surface lubricity and mold releasability, and has extremely good cleaning properties. An object of the present invention is to provide an image holding member whose surface layer is less damaged.

[Means for Solving the Problems 1 Effect] The present invention provides an image bearing member having a surface layer that holds an electrostatic image or a toner image, which contains a polymerizable monomer having a silicon atom in a side chain as a constituent component. It is constituted by an image holding member characterized in that it has at least two or more layers containing a graft polymer, the layer being the most distant from the conductive support.

The silicone-based graft polymer used in the present invention consists of a monomer that has a silicon atom in its side chain and a polymerizable functional group at the end, and a polymerizable monomer that does not have a silicon atom or has a polymerizable functional group at the end. Molecular weight 1,0 with a functional group
00 to io, o.

It is obtained by copolymerizing a macroheptanomer consisting of a relatively low molecular weight polymer such as O, and has a structure in which silicone-containing side chains are attached to the main chain in a branched manner.

Representative compounds are listed below as monomers having silicone in their side chains.

Monomer example (1) HL-C ・C■0 H3 Positive integer monomer example (2) Rnee H, -CH3 Monomer example (4) Rnie-H1 CHs n: Positive integer monomer example (5 ) One of the polymerizable monomers or macroheptanomers is selected to have an affinity with the resin to which the graft polymer is to be added. Examples include acrylic esters, methacrylic esters, styrene compounds, etc. .

Copolymerization ratio is 5wt% as silicone monomer content
The above is preferable.

The molecular weight of the obtained copolymer was 500 as a number average molecular weight.
from 100,000, especially from 1.000 to 10,000
is preferred.

Note that the molecular weight is measured by GPC (gel permeation chromatography).

Since the silicone-based graft polymer used in the present invention has the above structure, by appropriately selecting known monomers to be copolymerized, a coating solution containing a binder resin for forming a surface layer can be formed. Excellent compatibility,
Therefore, the resulting coating film has good transparency and has a long-lasting effect without migrating onto the surface layer or oozing out, and the silicone-containing branch part has no interfacial migration. Since it has excellent properties, surface modification can be achieved by adding a small amount.

Note that radical polymerization and ionic polymerization such as solution polymerization, suspension polymerization, and bulk polymerization can be applied as polymerization methods.
Radical polymerization by solution polymerization is convenient and preferred.

The appropriate amount of the silicone graft polymer added is 0.02 to 10% based on the solid weight of the surface rI'Ij layer,
Furthermore, 0.1 to 5% is preferable.

If the amount added is less than 0.02%, a sufficient surface modification effect cannot be obtained, while if it exceeds 10%, whitening may occur due to compatibility with the resin and photoconductive substance, which are the main components of the surface layer. It's coming.

The form of the layer containing the silicone-based graft π-coalescence is as follows: (1) When the surface layer itself is a light guide layer (second-
(Fig. 1); It is formed by applying a coating liquid in which a photoconductive polymer or a photoconductive powder is dispersed or dissolved in a binder and drying it. In addition, when a zero surface layer is formed on the photoconductive layer (Figure 2-2); (a) the surface layer is a relatively thin film (about 0.1 to 10 pm) and the image forming process is as described above. (b) The surface layer is a relatively thick film (approximately 10 to 50 pm) and the image forming process is different from (2).

In any of the above cases, a solution containing Ml 1 and material used to form at least two or more layers of debris including the layer, counting from the debris furthest away from the conductive support, is dispersed or dissolved in a solvent. The silicone-based graft polymer is added, and the resulting coating solution is coated in at least two layers on a suitable conductive support, photoconductive layer, or surface layer, and dried to form an image holding member. is created.

Here, as the binder resin, photoconductive substance, etc. contained in the surface layer composition, those commonly used in the field can be used.

The thickness of each layer of the surface layer containing the silicone-based graft polymer is suitably 0.1 μm or more and 5.071 m or less, more preferably 0.3 pm or more and 3.0 pm or less, and if the film thickness is less than 0.1 pm, Uniform coating is difficult,
On the other hand, if the thickness exceeds 5.0 μm, the layer in contact with the cleaning blade may be damaged before the effect of the silicone-based graft polymer contained in the layer in contact with the cleaning blade is exerted. The slipperiness decreases and the cleaning blade flips over.

On the other hand, if the film thickness is 0.1 μm or more and 5.0 pm or less, there will be no problem in coating properties, and the effect of the silicone graft polymer present in the layer in contact with the cleaning blade will not disappear. In addition, since the effect of the silicone-based graft polymer existing under the layer appears, the surface slipperiness is always good, especially when the film thickness is 0.3 μm.
If the thickness is 3.0 μm or less, both coating properties and surface slip properties are extremely good.

In addition, the P of each surface layer containing VJ 0.1 pm or more and 5.07 zm, preferably 0.3 μm or more and 3.0 μm or less (graph) of silicone-based fff coalescence! The higher the r number, the better.

This is because the effect of the silicone graft polymer on the surface slipperiness continues for the number of layers.

However, since these surface layers affect the charging characteristics and sensitivity of the image holding member, the total layer thickness is preferably 0.21 Lm or more and 30 μm or less, and more preferably 0.6 μm or more and 30 μm or less.

[Example 1 Synthesis example of silicone-based graft polymer] The monomer example (
50 parts (heavy water part, the same shall apply hereinafter) of the compound (Rney CH3, n=30) of 1), methyl methacrylate (MMA)
50 parts of azobisisobutyronitrile, 10 parts of azobisisobutyronitrile, and 80 parts of toluene were placed in a flask equipped with a condenser stirrer.
The reaction was carried out at 80° C. for 24 hours in a nitrogen atmosphere.

After the reaction, toluene and unreacted MMA were removed by vacuum distillation to obtain a solid reaction product.

Next, unreacted silicone polymer was extracted from the reaction product with n-hexane, and dried under reduced pressure to obtain a white powdery silicone graft polymer.

The silicone-based graft polymers (Samples I to ■) used in the following examples are shown in the table.

■ (2) R: -CH3 Styrene 30% n=20 ii(i) R: -C)+3 Styrene 50%n=3
0 ■ (1) R: -CHh MMA macro 30%n=30
Monomer■ (5) R: -C)lx MMA 30%n=
5 Example 1 100 parts of zinc oxide powder for electrophotography (parts by weight, the same applies hereinafter)
After thoroughly dispersing 0.5 parts of rose bengal, 5 parts of methanol, and 100 parts of toluene as a pigment in a ball mill, the solvent was removed by absorption. Butyral resin (trade name BM-1) was used as a binder to the dye-sensitized zinc oxide.

Sekisui Chemical Co., Ltd.! ! 20 parts of block incyanate, 20 parts of block incyanate
0.4 parts of triethanolamine as a curing agent, 50 parts of methyl ethyl ketone and 20 parts of ethanol as a solvent were added, and the mixture was dispersed again using a ball mill to obtain a photoconductive paint 4.

This was coated by dip coating on an 8oφ x 300mm aluminum cylinder that had been subjected to undercoat treatment, and was heated and cured at 120°C for 30 minutes. A photosensitive layer of m was formed.

Next, a conductive Ti0
2 (trade name: ECT-62 made by Titanium ■) were well dispersed in a ball mill to prepare a protective layer coating solution.

Furthermore, a coating material was prepared by adding 2 PM of the silicone-based graft polymer of Sample I as a solid content to this coating solution.

This was dip-coated onto the photosensitive layer and dried at ioOoC for 5 minutes to form a protective layer of 2ILm.

Furthermore, the same protective layer was laminated on top of this protective layer by dipping and drying once to shape the protective layer, thereby producing an electrophotographic photoreceptor.

This is referred to as photoreceptor l.

On the other hand, the following photoreceptor was prepared for comparison.

The 11th one was prepared in the same manner as photoreceptor 1 except that no surface modifier was added, and the second one was made in the same way as photoreceptor 1, with only the outermost layer having a thickness of 5.2 pLm among the two-layered protective layer. The third one is the outermost layer of the two-layer protective layer with 0.0
The film thickness was 8 μm, and the photoreceptor 2. Let them be photoreceptor 3 and photoreceptor 4.

However, the coating film on the surface of photoreceptor 4 was non-uniform, and obvious disturbances in film thickness were visually confirmed.

The durability of photoreceptors 1 to 4 was evaluated using an electrophotographic process consisting of -5.5 KV corona charging, image exposure, dry toner development, toner transfer to plain paper, and cleaning with a urethane rubber blade. Show the results.

With photoreceptor 1, stable high-quality images were obtained up to 7,000 copies.

The cleaning blade of photoreceptor 2 reversed when 400 sheets were copied.

Photoconductor 3 caused dot-shaped toner fusion on the surface layer at the stage of copying 3,500 copies.

Cleaning failure occurred in the photoreceptor 4 from the beginning of copying.

Example 2 Cadmium sulfide powder lOO part and diallyl phthalate resin as a binder (trade name: Guisodatsubu, Osaka Soda)
A photoconductive coating material was prepared by dissolving 15 parts of the product (manufactured by E.P. Co., Ltd.) and 0.5 parts of benzoyl peroxide in a mixed solvent of equal amounts of methyl ethyl ketone and xylene, and thoroughly mixing the mixture in a roll mill.

This was applied onto an 80φ x 300mm aluminum cylinder by dipping, and cured for 120"01lO minutes.
The photoconductive layer had a thickness of 0 ILm.

Next, a diallyl phthalate resin (described above) solution containing 3% by weight of benzoyl peroxide was applied thereon.

It was cured at 120° C. for 10 minutes to form a resin layer of 1107 tons.

Next, urethane acrylate resin (trade name Sonne, manufactured by Paint Co., Ltd.) is applied, cured by irradiation with ultraviolet rays, and IO
A layer of pm thickness was formed.

Furthermore, polysulfone (trade name Needel P1700, U
(manufactured by CC Corporation) was dissolved in 40 parts of chlorobenzene and 30 parts of methyl ethyl ketone, and 1.5 parts of silicone graft polymer II was added thereto as a solid content. This liquid was applied to the layer and dried at 100°C for 20 minutes.2.
Photoreceptor 5 is an electrophotographic photoreceptor prepared by forming 5 parts of waste and further coating the same solution once to form a surface layer of 5.0 parts in total.

On the other hand, the following photoreceptor was prepared for comparison.

The first one was made in the same manner as photoreceptor 5 except that no surface modifier was added, and the second one was photosensitive except that no surface modifier was added to the outermost surface layer. The third photoreceptor was made in the same manner as photoreceptor 5, and the third one was made in the same manner as photoreceptor 5, except that one surface layer was coated only once. do.

For photoreceptors 5 to 8, -order +6KV corona charging secondary AC
Evaluation was performed using an electrophotographic copying machine consisting of corona charging, simultaneous image exposure, full-surface light irradiation, dry toner development, toner transfer to plain paper, and cleaning with a urethane rubber blade. Show the results.

With photoreceptor 5, stable high-quality images were obtained up to 10,000 copies.

The cleaning blade of the photoreceptor 6 reversed when 500 sheets were copied.

The cleaning blade of the photoreceptor 7 was reversed at the stage of copying 500 sheets.

On the photoreceptor 8, black spots appeared due to toner fusion at the stage of copying 6,000 sheets.

Example 3 Ten parts of cutic casein produced by New Sealant were weighed out, dispersed in 90 parts of water, and then dissolved in 1 part of aqueous ammonia.

On the other hand, hydroxypropyl methylcellulose resin (trade name Metrose 603) 150. (manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 20 parts of water, and then the two were mixed to prepare a coating solution for an undercoat layer.

This liquid was applied to an 80φ x 300mm aluminum cylinder by dipping and dried at 80° C. for 10 minutes to form a 2 μm thick undercoat layer.

Next, add 10 parts of a disazo pigment having the following structure.

6 parts of cellulose acetate resin (product name: CAB-381 manufactured by Eastman ■) and 60 parts of cyclohexanone were mixed into 1φ
Dispersion was carried out for 20 hours using a sand mill apparatus using glass beads. 100 parts of methyl ethyl ketone was added to this dispersion, and the mixture was applied onto the undercoat layer by dip coating, followed by heating and drying at 100° C. for 10 minutes to form a charge generation layer with a coating weight of 0.1 g/cm 2 .

Next, add 10 parts of a hydrazone compound having the following structure.

and 10 parts of methyl methacrylate-styrene copolymer (trade name: MS-600, manufactured by Nippon Steel Chemical Co., Ltd.) were dissolved in 55 parts of chlorobenzene.

To this liquid, 0.1 part of the silicone graft polymer of sample (1) was added as solid content.

16. This was coated on the charge generation layer and dried with hot air at 100°C for 1 hour. A prepared electrophotographic photoreceptor having a μm-thick charge transport layer formed thereon is referred to as a photoreceptor 9.

Further, the liquid containing the sample m is applied onto the photoreceptor 9,
Hot air drying was performed at 100° C. for 1 hour to form a charge transport layer having a thickness of 4 μm (total 20 μm). The electrophotographic photoreceptor thus produced is referred to as a photoreceptor 10.

Further, the electrophotographic photoreceptor 9 prepared by applying the liquid containing sample m above on the photoreceptor 10 and drying it with hot air at 100° C. for 1 hour to form a charge transport layer with a total thickness of 24 μm was used as the photoreceptor 11. do.

On the other hand, for comparison, an electrophotographic photoreceptor was prepared in the same manner as photoreceptor 9 except that no surface modifier was added, and this was used as photoreceptor 1.
Set it to 2.

Photoreceptors 9 to 12 were attached to an electrophotographic copying machine having -5,6 KV corona charging, image exposure, dry toner development, toner transfer to plain paper, and cleaning process using a urethane rubber blade to evaluate image durability. . Show the results.

Photoconductor 9 provides stable high-quality printing up to 5,000 copies.
Ui image was fIJ.

The photoreceptor IO was stable and produced high-quality images up to 9,000 copies.

Photoreceptor 11 was able to produce stable, high-quality images up to 13,000 copies.

At the stage of copying 700 sheets, the image on the photoreceptor 12 ran in a band-like manner, resulting in white spots.

Example 4 One part of cutic casein produced by New Sealant was weighed out, dispersed in 90 parts of water, and then dissolved in 1 part of aqueous ammonia.

On the other hand, 3 parts of hydroxybutyl methylcellulose resin (described above) was dissolved in 20 parts of water, and the two were then mixed to prepare a coating solution for an undercoat layer.

This solution was applied to an 80φ x 300mm aluminum cylinder by dipping, dried for 0.10 minutes, and 1.O
A subtraction calendar with a thickness of iLm was formed.

Next, add 12 parts of a hirazoline compound having the following structure.

(manufactured by CC) was dissolved in 52 parts of chlorobenzene.

This solution was applied on the undercoat layer by immersion ffl, and heated at 100°C.
After drying for 1 hour, a charge transport layer of 1 Bpm was formed.

Next, add 10 parts of a disazo pigment having the following structure.

Polyvinyl butyral (product name S-LEC BM-5,
Sekisui Chemical■! 2) 5 parts and 30 parts of deftyl acetate to lφ
Dispersion was carried out for 20 hours using a sand mill apparatus using glass beads.

This dispersion was dip-coated onto the charge transport layer and heated to 100°C.
, and was dried for 5 minutes to form a charge generation layer having a thickness of 0.151 Lm.

Next, 5 parts of polyvinyl butyral (#) was dissolved in 30 parts of butyl acetate and 40 parts of ethanol, and 0.3 part of the silicone graft polymer of sample (1) was added thereto as solid content.

This solution was applied onto the above charge generation layer and dried for 10"05 minutes to form a layer with a thickness of 2.0 μm. Further, the same 2N solution was overcoated and dried to form a surface layer with a total thickness of 6.0 JLm. The electrophotographic photoreceptor thus prepared is referred to as photoreceptor 13.

Furthermore, for comparison, photoreceptor 1 was used except that no surface modifier was added.
Prepare an electrophotographic photoreceptor in the same manner as in step 3, and use it as photoreceptor 1.
Set it to 4.

The photoreceptors 13 and 14 are exposed to -5,6KV corona charging for one image, dry toner development, toner transfer to plain paper,
It was installed and evaluated in an electrophotographic copying machine that has a cleaning process using a urethane rubber blade. Show the results.

The photoreceptor 13 was stable and produced high-quality images up to 5,000 copies.

After about 300 copies were made of the photoreceptor 14, the edge of the cleaning blade was damaged, resulting in poor cleaning.

Effects of the Invention The present invention provides a graft polymer in which at least two scraps from the layer side farthest from the conductive support of an image holding member have a polymerizable monomer having a silicon atom in the side chain as a constituent component. By using an image holding member having a layer containing the rubber blade, problems such as turning over of the cleaning blade and chipping of edges due to friction between the cleaning blade and the surface of the image holding member, which occur in electrophotographic processes using cleaning means using a rubber blade, can be avoided. This has the remarkable effect of significantly improving cleaning performance and repeated durability.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a cleaning device that uses a cleaning blade to explain its operation. Symbol l is the cleaning device, 2 is the electrophotographic photoreceptor, 3 is the cleaning blade, 3a is the normal state of the cleaning blade, 3b is the state where the cleaning blade has been reversed, and A is the rotation direction of the electrophotographic photoreceptor. shows. 2-1 and 2-2 are cross-sectional views of an example of the electrophotographic photoreceptor of the present invention. FIG. 2-1 shows a case in which the surface layer itself is a photoconductive layer; A case in which a surface layer is formed on a photoconductive layer is shown. Reference numeral 4 indicates a conductive support, 5 indicates a light guide layer, and 6 layer lines.

Claims (1)

[Claims] 1. In an image holding member having a surface layer holding an electrostatic image or a toner image, a layer containing a graft polymer having as a constituent component a polymerizable monomer having a silicon atom in a side chain. An image-holding member comprising at least two layers of at least one of the layers most distant from the conductive support. 2. The content of the graft polymer is 0.02 to 1 in weight fraction in each layer containing the graft polymer.
The image holding member according to claim 1, wherein the image holding member is 0%. 3. In the layer containing the graft polymer, there are n layers, and the thickness of each layer in the n-1 layer counting from the layer farthest from the conductive support is 0.1 μm or more 5.0
The image holding member according to claim 1 or 2, wherein the image holding member has a diameter of μm or less.