JPS62208081A - Cleaning blade of photosensitive body having surface conductive layer for electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To provide a stable cleaning effect without deteriorating the quality of a copied image by using a polyurethane or the like having a conductive layer to constitute part or the whole of the surface of an elastic body forming a cleaning blade for cleaning a photosensitive body. CONSTITUTION:For example, a polyurethane sheet for a blade is formed and a conductive coating compd. is coated to part or the whole of the surface thereof at the time of forming the elastic body for forming the cleaning blade of the photosensitive body for an electrophotographic copying machine. Such sheet is then cut to a prescribed shape or the conductive coating compd. is coated thereon after the sheet is previously cut. The polyurethane is formed by bringing a polyisocyanate, polyol, and if necessary, chain extender into reaction in the conventional manner. The conductive coating compd. may be various coating compds. and is more preferably an urethane coating compd. contg. a conductive filler. The surface resistance value is considerably decreased and the sticking of a toner is hardly observed if the blade is constituted in the above-mentioned manner.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cleaning blade for cleaning toner remaining on the surface of a photoreceptor of an electrophotographic copying machine.

(Prior art) In an electrophotographic copying machine, a latent image formed on the surface of a photoconductor is developed with toner, and the toner image is transferred to recording paper. However, since the photoconductor is used repeatedly, some residual images remain on the surface of the photoconductor. It is necessary to clean the toner. To clean this residual toner, a method is widely used in which a blade made of a rubber-like elastic material is brought into sliding contact with the surface of the photoreceptor to scrape off the toner. The characteristics that the cleaning blade should have include thorough cleaning, no damage to the surface of the photoreceptor, excellent durability, and no unpleasant noises when sliding. Urethane rubber is the best rubber material that satisfies these characteristics, for example,
104840. 'mN 1983-30574, etc.

On the other hand, since the urethane blade γ itself is a dielectric material and has a volume resistivity of IQIIΩC- or higher, it is charged with static electricity due to friction with the drum and toner, and as a result, the cleaned toner adheres to the blade, reducing cleaning performance. . In addition, toner scatters around due to the force of static electricity, causing dirt and equipment trouble.

To this end, conventional methods have been taken to prevent toner from adhering to the blade by applying a charge opposite to the one charged to the blade to neutralize static electricity, but this requires a charge loading device. This hinders the reduction in size, weight, and power consumption of copying machines.

(Problems to be Solved by the Invention) An object of the present invention is to provide a photoreceptor cleaning blade for an electrophotographic copying machine that has excellent durability.

Another object of the present invention is to provide a photoreceptor cleaning blade for an electrophotographic copying machine that has a stable cleaning effect without deteriorating the quality of copied images.

A further object of the present invention is to provide an electrophotographic apparatus that provides electroconductivity to the cleaning blade itself, thereby eliminating the need for a charge load device for neutralizing static electricity, making it possible to reduce the size, weight, and power consumption of copying machines. An object of the present invention is to provide a photoconductor cleaning blade for a copying machine.

(Means for Solving the Problems) The present invention provides a cleaning blade for cleaning a photoreceptor of an electrophotographic copying machine, in which an elastic body forming the cleaning blade is made of polyurethane having a conductive layer on a part or all of the surface. The present invention relates to a photoreceptor cleaning blade for an electrophotographic copying machine, characterized in that:

In the present invention, the elastic body forming the cleaning blade is made of polyurethane having a conductive layer on part or all of its surface. The cleaning blade of the present invention can be obtained, for example, by creating a polyurethane sheet for a blade, applying a conductive paint to part or all of the surface of the sheet, and then cutting the sheet into a predetermined shape. Further, after cutting the polyurethane sheet into a predetermined shape, a conductive paint can be applied.

A polyurethane sheet for blades can be obtained by mixing and molding known raw materials for producing polyurethane. That is, the polyurethane is obtained by reacting a polyisocyanate, a polyol, and, if necessary, a chain extender.

The polyisocyanate used may be any polyisocyanate known in polyolethane chemistry, for example hexamethylene diisocyanate, isophorone diisocyanate), 4,4'-cyclohexylmethane noisocyanate, 2-4-tolylene neuisocyanate) (Z, 4-TDI), 2.8-)lylene diinocyanate (2,6-TDI), 4.4-lylene diisonane) (MDI), carposiimide modification MDI, polymethylene polyphenyl polyisocyanate (PAPI), orthotoluidine diincyanate (TODI), naphthylene diisocyanate (MD
I), quinrylene diisocyanate (XDI), etc., and one or more types can be used.

In addition, as a polyol, a divalent to trivalent molecule fi of 400 to
Toooo polyester polyols, polyether polyols, and the like are suitable. The polyester polyol may be either a condensed polyester polyol or a lactone polyester polyol obtained by a known method.
Saturated or unsaturated dibasic acids such as malic acid, acid anhydrides such as maleic anhydride and 7-talic anhydride, dialkyl esters such as dimethyl terephthalate, etc., and ethylene glycol,
It is a polyester polyol obtained by a condensation reaction with glycols such as propylene glycol, butylene glycol, quethylene glycol, dipropylene glycol, neopentyl glycol, and 1,6-hequinalene glycol. 1a acids such as adipate polyol, polybutylene anovate polyol, polyhexylene anovate polyol, etc.
7-novate polyols consisting of various glycols, polyethylene butylene anopate polyol, polyethylene no ethylene 7-carbon polyol, polyhexylene neobenzene adipate polyol, etc. Examples include aromatic polyols such as acbate polyols made of glycol, polyethylene adipate tere 7 tallate polyol made of various acids and one type of glyfur, and polyethylene adipate iso 7 tallate polyol.

Lactone-based polyester polyols are obtained by ring-opening polymerization of lactones such as ε-caprolactone and γ-butyrolactone, and polyols with various compositions can be obtained depending on the type of initiator. Initiators include glyfurs such as ethylene glycol and butylene glycol, polyether polyols such as polyoxypropylene glycol (PPG) and polyoxytetramethylene glycol (PTMG), condensed polyester polyols such as anovate, etc. are selected, all of which are suitable for use in the present invention. *In addition, polyols having two or more functionalities such as condensed polyester polyols and lactone polyester polyols are also suitable for use in the present invention.

Among them, copolymerization of poly-ε-caprolactone polyol, ethylene glycol, 1,4-butylene glycol, 1,8-hexylene glycol, trimethylolpropane, etc. with adipic acid using di- or trivalent silimethylolpropane as an initiator. Condensed polyester polyols are particularly preferred. As polyether polyols, polyoxytetramethylene glycol, polyoxypropylene glycol, etc. are preferred. Also suitable are copolymer polyols of polyether polyols and polyester polyols.

In the present invention, the reaction can be carried out in the presence of a suitable chain extender, if necessary. Examples of the chain extender include bi- to tetrafunctional polyols with a molecule fi of 400 or less and noamines having 7 primary or secondary terminal amide groups with a molecule fi of 400 or less.

Suitable chain extenders include, for example, (a) ethylene glycol, noethylene glycol, propylene glycol, dipropylene glycol, butanediol, hexane-1, glycerin, trimethylolpropane, pentaerythritol, sorbitol 1,4-cyclohexane; Polyols such as methanol and xylylene glycol (b) hydrazine, ethylene diamine, natho-2 methylene diamine, hexamethylene diamine, 1,4-cyclohexanthamine, phenylene diamine, xylylene diamine, 2.4-) lylennoamine, 4, 41-diaminodiphenylmethane, 3,3'-cyclo-4.4''-diaminodiphenylmethane, 1,4-dichloro-3,5-
Diamines such as noaminobenzene, 1.3-7'ropanediol seapara-7minopenzoate, methylenebisorthochloroaniline (MOCA), etc. (C) Alkanolamines such as ethanolamine, jetanolamine, triethanolamine, etc. (d) Obtained by adding propylene oxide and/or ethylene oxide to hydroquinone, pyrogallol, 4.4'-iv propylidene diphenol, aniline, and the above polyols, y amines, and alkanolamines in any order. Examples include polyols having a molecule j of 1400 or less.

Polyurethane may be produced by any known method, and both the one-shot method and the prepolymer method are suitable. For example, to produce by the prepolymer method, polyisocyanate and polyol are reacted in advance at about 60 to 90°C for about 30 minutes to 2 hours to form a prepolymer, and the remaining polyol and chain extender are added and mixed as necessary. Further, if necessary, the uncured reaction solution may be degassed and poured into a mold heated to about 80 to 150° C. to be cured. Remove the cured molded product from the mold and heat it at about 100 to 160°C for about 30 minutes to 2
Post-cure for 0 hours to terminate the reaction. This polyurethane may be in any form such as solution type polyurethane, emulsion type polyurethane, or two-component reaction type urethane.

Various types of conductive paints can be used, but urethane paints containing conductive fillers are particularly preferred. Various known paints can be used as urethane paints, and examples of one-component paints include Niboran 2301.2302.2304 (Japan Polyurethane 9).
1) As a two-component curing paint, Takene) D-202/
A combination of Takelac U-27, etc. (manufactured by Takeda Pharmaceutical), Niboran 3002.3004, etc. (the hardening agent is Coronate L, H
L, 3015, etc.), moisture-curing urethanes such as Takene) M2O3, M2O3, etc. (manufactured by Takeda Pharmaceutical Co., Ltd.), So7 Lannate EM100. EM400゜EM500 (Toyo Rubber Industries g1), Superflex 200, 360 (
(manufactured by Kogyo Seiyaku Co., Ltd.).

As the conductive filler, for example, carbon black, graphite, metal fine powder, metal oxide powder, and other materials can be used. Preferred specific examples of carbon black include Ketjen black, acetylene black, and the like. For example, product names include Ketjen Black EC and ECDJ-60 manufactured by Lion Corporation.
0, Vulcan XC-72 manufactured by Cabot, Toka Black #4500 manufactured by Tokai Carbon Co., Ltd., $
5,500 and so on. Fine metal powders include powders of gold, silver, copper, nickel, etc.; metal oxide powders include zinc oxide type (Hakusui Chemical Industry Co., Ltd., 23K), titanium oxide type (Meisei Shokai Co., Ltd., AE-755), tin oxide, Antimony-based (Sumitomo Aluminum, FF-202), tin oxide-based (Mitsubishi Metals, Elcom Tl-20, Tl-22>,
Zinc oxide, aluminum-based (Sumitomo Aluminum, FW
lol.

102) Other materials include mica fine powder, lath fine particles, conductive powder filler made by coating non-conductive particles such as alumina with tin oxide, metal, etc., and conductive shorts such as chopped stainless steel fiber strands. Examples include fibers. Especially carbon black and particle size 10
A filler with fine particles of less than μ is preferable because it does not damage the surface of the photoreceptor drum and does not cause black streaks due to poor cleaning even if it falls off. Usually 0.5 to 100 parts, preferably about 2
It is preferable to mix up to 50 parts of the conductive paint. As a method for applying the conductive paint, any of the methods generally used for applying paints can be used, such as coating with a doctor blade, roll coater, etc., spraying, and dipping. Further, drying is preferably carried out at room temperature to 150°C, preferably 60 to 100°C. The thickness of the conductive layer is usually about 2 to 100 μm, preferably about 5 to 30 μm.

The conductive layer may be formed on the entire surface of the cleaning blade, or it may be formed on only one part of the surface.It is particularly effective to provide the conductive layer on the top and/or bottom surface of the hexahedron of the blade. It is.

(Example) Reference examples, working examples, and comparative examples will be described below.

Reference example 1 (Creation of polyurethane sheet for blade) (1
) Synthesis of prepolymer Poly(neopentyl-1,6-hexamethylene) activate diol, Tuborane 4070, Nippon Polyurethane Co., Ltd., molecular fi 2000) 1000 g and diphenylmethanoinanate (Nippon Polyurethane Co., Ltd., Millionaire)
MT) was reacted at 80° C. for 3 hours in a nitrogen stream to obtain an NGO group-terminated prepolymer. The NC○ group concentration of the obtained prepolymer was 18.2111 eq/g.

(2) Preparation of polyurethane sheet A mixture of Niboran 4070 (39.9 g) as a curing agent and 22.8 g of 1,4-butanediol was added to 300 g of the above prepolymer, mixed, and a 50 cm x 30
Casting in cIIIX 2 am mold,
After reacting at 110°C for 2 hours, post-curing was performed at 80°C for 12 hours to prepare a polyurethane sheet.

Reference Example 2 Niboran 2301 (manufactured by Nippon Polyurethane, solution-type polyurethane, solid content 40 wt%) and Ketjen Black ECDJ-6oo were added at a solid content ratio of polyurethane/EC
A conductive urethane paint (1) was obtained by dispersing using a single sand mill so that DJ-600=10071.

Reference Example 3) EM400 (manufactured by Toyo Rubber Industries, Ltd., cationic polyurethane dualulsion, solid content 40 wt%),
A dispersion of Ketjen Black EC in water using a surfactant (containing 10 qt% of carbon black) was mixed at a solid content ratio of 40/2 to form a conductive urethane emulsion paint (II). Obtained.

Reference Example 4 Tin oxide powder FT was added to Niboran 2304 (manufactured by Nippon Polyurethane, solution-type polyurethane, solid content 35 wt%).
-201 (Meisei Shokai) was mixed at a solid content ratio of 100/20 and dispersed in a sand mill to obtain a conductive urethane paint. Immediately before use, 5 parts of Coronet L, a polyisocyanate curing agent, was added to 120 parts of the paint and mixed thoroughly to obtain a conductive paint (I [[)].

Examples 1 to 3 The polyurethane sheet for blades obtained in Reference Example 1 was
A cleaning blade of the present invention was prepared by cutting a piece of size 5 cm x 3 c @ x 2 ta and applying each of the conductive paints of Reference Examples 2 to 4 to a thickness of 15 μ on the entire surface by dipping. Obtained. The surface resistance value of the obtained cleaning blade was determined by pressing two square foil electrodes with a side of 25 m on each blade with a load of 450 g per sheet through an insulating plate at a distance of 25 m. Use a digital multimeter (manufactured by Iwatsu Denshi, S) to measure the resistance.
C-7403). The results are shown in Table 1.

Comparative Example 1 The polyurethane sheet of Reference Example 1 was cut in the same manner as in the example, and a cleaning blade without conductive paint was used as a comparative example. The surface resistance value of this cleaning blade cannot be measured by the method of the example (more than 3X10'Ω), so
High resistance meter 4329 manufactured by Yokogawa Hewlett Packard Card Company
Using A, a sheet of 8 cm x 8 cm x 2 en was separately prepared and measured. The results are shown in Table 1.

Table 1

Claims (2)

[Claims] (1) A cleaning blade for cleaning a photoreceptor of an electrophotographic copying machine, wherein an elastic body forming the cleaning blade is made of polyurethane having a conductive layer on a part or all of the surface. Photoconductor cleaning blade. (2) The cleaning blade according to claim 1, wherein the conductive layer is polyurethane containing a conductive filler.