JP2006208594A - Cleaning blade for electrophotographic copying machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning blade for an electrophotographic copying machine having superior durability and demonstrating superior toner scraping property, without relying on the temperature environment. <P>SOLUTION: The cleaning blade consists of polyurethane composite hardened body 1, containing particles of low hardness 5 indicated in (A) in the following section, and at least a sliding contact part 3 in the outer periphery of the hardened body 1 is formed in a skin layer 4 that does not contain the particles of low hardness 5, and the particles of the low hardness 5 are dispersed in parts other than the skin layer 4. (A): the particles having low hardness have an average particle diameter within the range of 0.1 to 0.5 mm, and the hardness is lower than in the skin layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic copying machine cleaning blade for removing toner remaining on an outer peripheral surface of a photosensitive drum or the like.

  The electrophotographic copying machine uniformly charges the outer peripheral surface of the photosensitive drum, and then exposes the outer peripheral surface via a copy image of the copy object, thereby forming an electrostatic latent image on the outer peripheral surface. In general, the electrostatic latent image is of a type in which a charged toner is attached to form a toner image and transferred to a copy paper or the like to perform copying.

  In such an electrophotographic copying machine, since toner remains on the outer peripheral surface of the photosensitive drum after the toner image is transferred, it is supported on the outer peripheral surface of the photosensitive drum 8 by a plate-like holder 22 as shown in FIG. The cleaning blade 21 is brought into sliding contact, and the residual toner is scraped off and removed at the sliding contact portion 21a.

The cleaning blade 21 is usually made of an elastic body, and among them, one made of a polyurethane resin having excellent mechanical properties such as wear resistance is awarded (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 9-212058

  However, a polyurethane resin generally used for a cleaning blade tends to be resinized at low temperatures (hardness increases and deteriorates in elasticity), and tends to induce rubberization (excessive elasticity) at high temperatures. For this reason, conventional polyurethane resin cleaning blades ensure stable scraping of toner from low temperature (10 ° C) to high temperature (32 ° C) environment as the usage environment of electrophotographic copying machines diversifies. The reality is that it was difficult. On the other hand, in order to improve the toner scraping property, it is said that it is effective to increase the hardness of the polyurethane resin forming the cleaning blade and further improve the pressing surface pressure against the photosensitive drum with a high pressing force. However, if the polyurethane resin is pressed with the hardness increased as described above, the pressing resistance from the photosensitive drum is also increased, so that the blade is likely to be chipped or worn. Therefore, simply increasing the hardness of the polyurethane resin does not solve the problem, and it is required to ensure the durability against the pressing resistance, but it is still insufficient.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a cleaning blade for an electrophotographic copying machine that is excellent in durability and exhibits excellent toner scraping properties without depending on the temperature environment. To do.

In order to achieve the above object, the cleaning blade for an electrophotographic copying machine of the present invention is a cleaning blade that removes residual toner on the surface of the mating member by sliding contact with the mating member such as a photosensitive drum. Is composed of a cured product of a polyurethane composition containing the low hardness particles shown in (A) below, and at least the sliding contact portion on the outer periphery of the cured product is formed on the skin layer containing no low hardness particles, The low hardness particles are dispersed in portions other than the skin layer.
(A) Low hardness particles having an average particle size in the range of 0.1 to 0.5 mm and lower hardness than the skin layer.

  That is, the present inventors have intensively studied to solve the above problems. In the course of that research, the surface hardness of the cleaning blade (especially the surface hardness of the sliding contact portion with the mating member such as the photosensitive drum) is increased to ensure a high surface pressure and to achieve high toner scraping, It was recalled that the hardness inside the cross section of the blade was lowered to reduce endurance stress. In order to realize such a concept, the present inventors have further studied. As a result, the blade is formed using a polyurethane composition containing low-hardness particles having a specific average particle diameter, and the low-hardness particles are dispersed inside the blade, and at least at the outer periphery of the blade. In the sliding contact portion, a skin layer formed of the polyurethane composition containing no low-hardness particles is used, and a hardness difference is caused between the inside of the blade (a portion other than the skin layer; the same applies hereinafter). . Thereby, the slidable contact portion surface has a reduced nip width (contact width) at the time of sliding contact with the photosensitive drum and the like, and can reduce friction as the surface pressure increases. The stress at the time of sliding contact can be absorbed by deformation of the low-hardness particles, and the proportion of polyurethane resin is reduced by the inclusion of the low-hardness particles, so the toner scraping performance is unstable due to changes in the temperature environment. It has been found that the problem is solved and the present invention has been reached.

  As described above, the cleaning blade for an electrophotographic copying machine of the present invention comprises a cured product of a polyurethane composition containing low-hardness particles having a specific average particle diameter, and at least the sliding contact portion on the outer periphery of the cured product, The low hardness particles are formed in the skin layer free of the low hardness particles, and the low hardness particles are dispersed in a portion other than the skin layer (inside the blade). For this reason, the surface of the sliding contact portion has high hardness, can exhibit excellent toner scraping properties and low friction, and the low hardness particles inside the blade can absorb stress such as compression and tensile stress. It is possible to absorb the stress during sliding contact and to have excellent durability. Furthermore, since the ratio of the polyurethane resin is suppressed by the low-hardness particles, the toner scraping performance due to changes in the temperature environment is stable, and excellent performance as a cleaning blade for an electrophotographic copying machine can be exhibited.

  In particular, when the low hardness particles of (A) are made of urethane elastomer (TPU), polyester elastomer (TPEE), fluorine rubber, silicone rubber, cellulose polymer, etc., the low hardness inside the blade Therefore, the present invention can be suitably applied to the cleaning blade for an electrophotographic copying machine of the present invention.

  Further, when the hardness of the skin layer is set in the range of 70 to 85 IRHD, more excellent toner scraping property and the like can be exhibited.

  Furthermore, when the thickness of the skin layer is set in a range of 0.1 to 0.5 mm, various performances of the cleaning blade for an electrophotographic copying machine of the present invention can be suitably exhibited.

  When the hardness inside the blade (portion other than the skin layer) is set in a range of 60 to 80 IRHD, the improvement in the durability becomes more remarkable without impairing the performance balance of the cleaning blade.

  Next, an embodiment of the present invention will be described.

  The cleaning blade for an electrophotographic copying machine of the present invention comprises, for example, a polyurethane composition cured body 1 as shown in FIG. 1 and is supported by a plate-like holder 2 for use. The polyurethane composition cured body 1 is composed of a cured body of a polyurethane composition containing specific low-hardness particles 5, and is in sliding contact with at least a counterpart member (such as a photosensitive drum) on the outer periphery of the cured body. The most characteristic feature is that the portion 3 is formed in the skin layer 4 containing no low hardness particles 5 and the low hardness particles 5 are dispersed in portions other than the skin layer 4. In addition, in FIG. 1, although the skin layer 4 is formed over the outer periphery perimeter of the said polyurethane composition hardening body 1, it may be such an aspect. As another embodiment, for example, a skin layer 4 may be formed as shown in FIG.

  The polyurethane composition (excluding the low hardness particles 5), which is a forming material of the polyurethane composition cured body 1, is obtained using polyisocyanate and polyol.

  The polyisocyanate is not particularly limited. For example, 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2 , 6-TDI), 3,3′-vitrylene-4,4′-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, 2,4-tolylene diisocyanate uretidinedione (2,4- Dimer of TDI), 1,5-naphthylene diisocyanate, metaphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), carbodiimide-modified MDI, orthotoluidine diisocyanate, Examples thereof include diisocyanates such as silylene diisocyanate, paraphenylene diisocyanate and lysine diisocyanate methyl ester, triisocyanates such as triphenylmethane-4,4 ′, 4 ″ -triisocyanate, and polymeric MDI. These may be used alone or in combination of two or more. Among these polyisocyanates, MDI is preferably used from the viewpoint of wear resistance.

  The polyol used together with the polyisocyanate is not particularly limited, and examples thereof include polyester polyols such as polyester diol and polyester triol, polyether polyols such as polycaprolactone, polycarbonate, polyoxytetramethylene glycol, and polyoxypropylene glycol. Can be given. These may be used alone or in combination of two or more.

  As the polyester polyol, a hydroxyl polyester polyol produced from a polybasic organic acid and a polyol and having a hydroxyl group as a terminal group is preferably used. Examples of the polybasic organic acids include saturated fatty acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, isosebacic acid, maleic acid, fumaric acid and the like. Obtained by dimerization of saturated fatty acids, dicarboxylic acids such as aromatic acids such as phthalic acid, isophthalic acid, and terephthalic acid, acid anhydrides such as maleic anhydride and phthalic anhydride, dialkyl esters such as dimethyl terephthalate, and unsaturated fatty acids. And dimer acid. Examples of the polyol used together with the polybasic organic acid include diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, 1,6-hexylene glycol, Examples include triols such as methylolethane, trimethylolpropane, hexanetriol, and glycerin, and hexaols such as sorbitol.

  Moreover, as said polyether polyol, what is manufactured by ring-opening polymerization or copolymerization of cyclic ether is used suitably. Examples of the cyclic ether include ethylene oxide, propylene oxide, trimethylene oxide, butylene oxide, α-methyltrimethylene oxide, 3,3′-dimethyltrimethylene oxide, tetrahydrofuran, dioxane, dioxamine and the like.

  And in this invention, the polyester polyol obtained from dicarboxylic acid and diol is used suitably from a viewpoint of abrasion resistance among said series of polyols. More preferred are polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexylene adipate, and a copolymer of ethylene adipate and butylene adipate.

  In addition to the polyisocyanate and polyol, the polyurethane composition (excluding the low hardness particles 5) includes a chain extender, a catalyst, a foaming agent, a surfactant, a flame retardant, a colorant, a filler, a plasticizer, and a stabilizer. An agent, a release agent and the like can be appropriately mixed and used.

  Examples of the chain extender include 1,4-butanediol (1,4-BD), ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexane. Examples include polyols having a molecular weight of 300 or less, such as dimethanol, xylene glycol, triethylene glycol, trimethylolpropane (TMP), glycerin, pentaerythritol, sorbitol, and 1,2,6-hexanetriol. These may be used alone or in combination of two or more.

  Examples of the catalyst include 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU), 1,5-diazabicyclo (4,3,0) -nonene-5 (DBN), and the following general formula ( Examples thereof include diazabicycloamine salts shown in 1), amine compounds such as tertiary amines, and organometallic compounds such as organotin compounds. Among them, DBU, DBN and a diazabicycloamine salt represented by the following general formula (1) are used as a catalyst, and when cured in the presence thereof, the resulting cleaning blade has a low temperature cleaning property and a high temperature vibration. It is preferable because it has excellent absorption characteristics and permanent set becomes small.

  Examples of the tertiary amine include trialkylamines such as triethylamine; tetraalkyldiamines such as N, N, N ′, N′-tetramethyl-1,3-butanediamine; aminoalcohols such as dimethylethanolamine; Ethoxylated amines; Ethoxylated diamines; Ester amines such as bis (diethylethanolamine) adipate; Triethylenediamine (TEDA); Cyclohexylamine derivatives such as N, N-dimethylcyclohexylamine; N-methylmorpholine, N- (2-hydroxy Morpholine derivatives such as propyl) -dimethylmorpholine; piperazine derivatives such as N, N′-diethyl-2-methylpiperazine and N, N′-bis- (2-hydroxypropyl) -2-methylpiperazine.

  Examples of the organic tin compound include dialkyltin compounds such as dibutyltin dilaurate and dibutyltin di (2-ethylhexoate), stannous 2-ethylcaproate, stannous oleate, and the like.

  The low hardness particles 5 used together with the polyurethane composition have an average particle diameter in the range of 0.1 to 0.5 mm, and the hardness (skin of the polyurethane composition cured body not containing the low hardness particles 5). A material whose hardness is lower than the hardness of the layer 4 is used. The average particle diameter of the low hardness particles 5 is preferably in the range of 0.1 to 0.5 mm, and more preferably in the range of 0.2 to 0.4 mm. That is, if the average particle size of the low hardness particles 5 is less than 0.1 mm, the effect of reducing the durability stress when the photosensitive drum or the like is in sliding contact cannot be obtained, and conversely, the average particle size is 0.5 mm. This is because, if it exceeds, the low hardness particles 5 come out on the surface of the cleaning blade and deteriorate the toner scraping property. The average particle diameter of the low hardness particles 5 is a value derived using a sample arbitrarily extracted from the population. In addition, if the particle size is not uniform, as in the case of a particle shape that is not a true sphere but an elliptical sphere (a sphere with an elliptical cross section), the simple average value of the longest diameter and the shortest diameter is the particle diameter of the particle. To do.

  The material for forming the low hardness particles 5 is not particularly limited as long as the particles 5 have a lower hardness than the cured product of the polyurethane composition that is the main component of the cleaning blade of the present invention. For example, polyamide elastomer (TPAE), acrylic rubber (ACM), styrene elastomer (SBC), phenol resin, epoxy resin, olefin elastomer (TPO), urethane elastomer (TPU), polyester elastomer (TPEE) ), Elastomers obtained by using fluorine rubber, silicone rubber and cellulose polymer alone or in combination of two or more. Among these, urethane elastomer (TPU), polyester elastomer (TPEE), fluorine rubber, silicone rubber, and cellulose polymer are preferably used as the material for the low hardness particles because they can easily produce low hardness particles. .

  The blending ratio of the low hardness particles 5 is set in the range of 5 to 40 parts with respect to 100 parts by weight (hereinafter, abbreviated as “part”) of the polyurethane composition as the main component of the cleaning blade of the present invention. Preferably, it is in the range of 10 to 30 parts. That is, if the low hardness particles are less than 5 parts, it is difficult to obtain a desired durability stress reducing effect. Conversely, if the low hardness particles exceed 40 parts, the cleaning blade becomes too soft and slides with a mating member such as a photosensitive drum. This is because there is concern about a decrease in surface pressure at the time of contact.

  The cleaning blade of the present invention can be produced according to a conventional method using each of the above materials. Specifically, it can be produced according to a prepolymer method, a semi one-shot method, or a one-shot method. Of these, the semi-one shot method is preferably used from the viewpoint of excellent workability.

  The cleaning blade of the present invention is manufactured as follows, for example, according to the semi-one shot method. That is, first, the above polyisocyanate and polyol are prepared, both are mixed in an appropriate mixing ratio, and reacted under appropriate reaction conditions to prepare a urethane prepolymer (main agent liquid). On the other hand, the above polyol, a chain extender, a catalyst and the like are prepared, blended at an appropriate blending ratio, and mixed under an appropriate mixing condition to prepare a curing agent solution. Next, the main agent liquid and the curing agent liquid are mixed in a predetermined ratio, and specific low hardness particles 5 separately prepared are dispersed in the mixed liquid in a predetermined ratio. The low hardness particles 5 may be previously dispersed in the main agent liquid or the curing agent liquid. Then, the liquid mixture thus obtained is injected into a cleaning blade molding die on which the plate-like holder 2 is held, and is reacted and cured. Thereafter, the obtained cured body is taken out from the mold. As shown in FIG. 1, the cured body thus obtained is integrally formed with the plate-like holder 2, and the low hardness particles 5 are dispersed inside the cross section. At this point, depending on molding conditions and the like, as shown in the figure, a skin layer 4 that does not contain the low hardness particles 5 may be formed on the outer periphery of the cured body. Prepared polyurethane composition (similar to the above polyurethane composition except that no low-hardness particles are not contained), and this is used as the outer peripheral surface of the cured body (at least the outer periphery of the portion that becomes the sliding contact portion 3) The surface) is coated and then cured to form the skin layer 4. In this way, the intended cleaning blade can be obtained. The low-hardness particle-free polyurethane composition is the same as the polyurethane composition described above.

  The thickness of the skin layer 4 is preferably set in the range of 0.1 to 0.5 mm, and more preferably in the range of 0.2 to 0.5 mm. That is, when the thickness of the skin layer 4 is less than 0.1 mm, the straightness in the longitudinal direction (the photosensitive drum sliding contact direction) in the sliding contact portion 3 of the blade cannot be sufficiently obtained. This is because if the thickness of 4 exceeds 0.5 mm, the blade may be chipped due to endurance stress. The thickness of the skin layer 4 is measured by cutting the blade and examining the cross section with a magnifier.

  The hardness of the skin layer 4 is preferably set in the range of 70 to 85 IRHD, and more preferably in the range of 75 to 80 IRHD. That is, if the hardness of the skin layer 4 is less than 70 IRHD, the desired toner scraping performance cannot be obtained sufficiently, and conversely, if the hardness of the skin layer 4 exceeds 85 IRHD, the chipping of the blade due to endurance stress may occur. This is because it may occur. The hardness (IRHD) of the skin layer 4 is measured according to JIS K 6253, and can be measured by, for example, a Wallace microhardness meter manufactured by Wallace (HW WALLACE). .

  The hardness inside the blade (portion other than the skin layer) is preferably set in the range of 60 to 80 IRHD, more preferably in the range of 65 to 75 IRHD. That is, if the internal hardness of the blade is less than 60 IRHD, the nip width with the photosensitive drum may be increased, or the cleaning performance may be decreased. Conversely, if the internal hardness of the blade exceeds 80 IRHD, a desired durability may be obtained. This is because the stress reduction effect cannot be obtained sufficiently. The internal hardness (IRHD) of the blade is measured according to JIS K 6253 with respect to the blade cross section, and can be measured, for example, by a Wallace microhardness meter manufactured by Wallace. Further, since the low hardness particles 5 are present in a dispersed state inside the blade, and the measurement value is likely to vary, the hardness at about 10 locations on the blade cross section is measured, and the average value is obtained. Take.

  The dimensions of the cleaning blade of the present invention are not particularly limited. Usually, the thickness (d) is set in the range of 2 to 4 mm, and the length in the longitudinal direction (photosensitive drum sliding contact direction) is set. The range is set to 230 to 350 mm, and the length in the width direction (l) is set to a range of 10 to 20 mm (see FIG. 1).

  Note that the cleaning blade of the present invention is not necessarily formed integrally with the plate-like holder 2 as shown in FIG. 1, and may be adhered to the surface of the plate-like holder 2 later.

  The cleaning blade of the present invention thus obtained is used for electrophotographic copying machines such as copying machines and printers. In particular, a full color LBP (laser beam printer) that requires high surface pressure is required. It can be suitably used for use.

  Next, examples will be described together with comparative examples.

  First, prior to Examples and Comparative Examples, the following materials were prepared.

[Polyol]
Manufactured by Dainippon Ink and Polybutylene Adipate (Mn: 2000)

[MDI]
Millionate MT manufactured by Nippon Polyurethane Industry

[1,4-BD]
1,4-butanediol, manufactured by Mitsubishi Chemical Corporation

[TMP]
Made by Guangei Perstorp, trimethylolpropane

〔catalyst〕
Sankyo Air Products, DABCO (triethylenediamine)

[Particle a]
Cellulosic low hardness particles with an average particle size of 0.1 mm (D-100, manufactured by Kojin Co., Ltd.)

[Particle b]
Fluorine-based low-hardness particles with an average particle size of 0.5 mm (Asahi Glass Co., Ltd., Fullon CD086)

[Particle c]
Styrenic low hardness particles having an average particle size of 0.05 mm (SGP-150C, manufactured by Soken Chemical Co., Ltd.)

[Particle d]
Polyethylene low hardness particles with an average particle size of 0.6 mm (Sumitomo Seika Chemicals, Flow Bead CL8007)

  Next, the main agent liquid (urethane prepolymer) and the curing agent liquid in the urethane compositions A to B were prepared at the ratio shown in Table 1 below. Specifically, the main agent solution is prepared by using the materials for the main agent solution shown in Table 1 below, and blending them in the proportions shown in the same table, and then under conditions of 80 ° C. × 3 hours in a nitrogen atmosphere. Prepared by reaction. Moreover, the said hardening | curing agent liquid also uses each material for hardening | curing agent liquid shown in following Table 1, and these are the ratios shown in the same table [The addition amount (ppm) with respect to 100 weight part (PU) of urethane composition whole quantity (PU) only]. )] And then reacted under conditions of 80 ° C. × 1 hour in a nitrogen atmosphere.

[Examples 1 to 3, Comparative Examples 1 to 4]
A urethane composition (the main agent liquid and the curing agent liquid are in an unmixed state) and predetermined particles are blended in the proportions shown in Table 2 below, mixed with a stirring blade for 30 seconds while being vacuum degassed, and then held in a plate shape It was poured into a cleaning blade mold (140 ° C.) in which the metal fittings were arranged and cured. And after removing the obtained plate-shaped holding metal fitting with a cured body, it is molded into a predetermined shape. Further, except for Comparative Examples 1 and 2, the cured body material and the cured body material A similar urethane composition (containing no particles) was coated and heat-treated to form a skin layer (400 μm). In this way, a target cleaning blade with a holding bracket was obtained (see FIG. 1). The cleaning blade was formed such that its thickness (d) was 4 mm, the length in the longitudinal direction (photosensitive drum sliding contact direction) was 330 mm, and the length in the width direction (l) was 10 mm.

  The characteristics of the cleaning blades of Examples and Comparative Examples thus obtained were evaluated according to the following criteria. These results are also shown in Table 2 below.

[Sliding surface hardness (IRHD)]
The hardness of the surface of the sliding contact portion (skin layer surface) of the cleaning blade was measured based on JIS K 6253 using a Wallace microhardness meter manufactured by Wallace (HW WALLACE).

[Internal hardness (IRHD)]
The central portion of the cleaning blade was cut, and the 10-point average hardness inside the cross section was measured based on JIS K 6253 using a Wallace microhardness meter manufactured by Wallace (HW WALLACE).

[Pressing force]
The cleaning blade is brought into contact with the outer peripheral surface of the cylindrical virtual photoconductor (outer diameter 30 mm, outer peripheral width 10 mm) in a state inclined by 24 ° from the tangent line, and then pushed in at a right angle of 1 mm from the tangent line. The pressing force W (g / cm) received by the virtual photoconductor was measured with a load cell.

[Nip width]
In the pressing force measurement state, the blade contact portion was enlarged and observed with an optical microscope, and the nip width A (cm) was measured.

[Blade surface pressure]
From the values of the pressing force W (g / cm) and the nip width A (cm) obtained by the above measurement, the blade surface pressure P (g / cm ² ) was calculated by the following mathematical formula (1).

[Particle crossability]
The central portion of the cleaning blade was cut, and the state of particle crossing in the cross section was magnified and observed with an optical microscope. And the average of the space | interval of the adjacent particle | grains was measured. That is, the case where the average of the interval is in the range of 0.1 to 0.5 mm is ◯, the case where it is 0.05 mm or more and less than 0.1 mm, or the case where it is in the range of 0.5 mm or more and less than 1 mm is Δ Evaluation was made as x when the thickness was less than 0.05 mm or 1 mm or more.

[Chip resistance]
A cleaning blade is incorporated into a commercially available laser printer (printing speed: 22 sheets / min), and in a prescribed environment (low temperature (10 ° C), room temperature (23 ° C), high temperature (32 ° C)) 20,000 images were printed in A3 size. And the presence or absence of the edge part (sliding contact part) of the cleaning blade after the said 20,000 image printing was observed using the scanning electron microscope at 500-times multiplication factor. The evaluation was evaluated as “◯” when there was no chipping, “Δ” when the chipping was small and no practical problem, and “X” when the chipping was large and had a practical problem.

[Image evaluation]
The image quality of the copy image obtained in the above evaluation of chipping resistance was evaluated visually. In other words, when the characters were copied and there was no problem with the copied image and the thin line was clearly copied, ○, slightly inferior to the above evaluation of ○, but when the copied image was obtained, Δ, fogging, streaks Those with a large amount of etc. that appear to be defective in the copied image are displayed as x.

  From the results of Table 2 above, the cleaning blades of the examples are all made of a polyurethane composition cured body containing specific low hardness particles, and the sliding contact portion on the outer periphery of the cured body does not contain the low hardness particles. Since the low hardness particles are dispersed in portions other than the skin layer formed on the skin layer, the surface hardness of the sliding contact portion is high and the hardness inside the blade is low. The pressing force, nip width, and blade surface pressure are appropriate, and the effect of reducing endurance stress due to sliding contact is expected, and an increase in surface pressure due to nip width reduction is seen. Improvements and wear reduction effects are also expected. Moreover, it turns out that it is excellent in particle crossability, and is excellent in chipping resistance and image evaluation.

  On the other hand, the cleaning blades of Comparative Examples 1 and 2 do not contain low-hardness particles and are not formed with a skin layer. Poor chipping properties. In the cleaning blade of Comparative Example 3, since the average particle diameter of the dispersed particles is too small as 0.05 mm, the effect of reducing the durability stress due to the sliding contact cannot be obtained. In the cleaning blade of Comparative Example 4, since the average particle size of dispersed particles is too large as 0.6 mm, the particles come out on the surface of the cleaning blade and deteriorate the toner scraping property. Inferior to

It is a longitudinal cross-sectional view which shows an example of the cleaning blade of this invention.

It is a longitudinal cross-sectional view which shows the other example of the cleaning blade of this invention.

It is explanatory drawing which shows the usage example of a cleaning blade.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polyurethane composition hardening body 2 Plate-shaped holder 3 Sliding contact part 4 Skin layer 5 Low hardness particle

Claims (5)

A cleaning blade for removing residual toner on the surface of a mating member by sliding contact with a mating member such as a photosensitive drum, wherein the cleaning blade cures a polyurethane composition containing low-hardness particles shown in (A) below. And at least the sliding contact portion on the outer periphery of the cured body is formed in the skin layer free of the low hardness particles, and the low hardness particles are dispersed in a portion other than the skin layer. Cleaning blade for electrophotographic copying machines.
(A) Low hardness particles having an average particle size in the range of 0.1 to 0.5 mm and lower hardness than the skin layer.   The low hardness particles of (A) are formed using at least one selected from the group consisting of urethane elastomer (TPU), polyester elastomer (TPEE), fluorine rubber, silicone rubber, and cellulose polymer. The cleaning blade for an electrophotographic copying machine according to claim 1.   The cleaning blade for an electrophotographic copying machine according to claim 1 or 2, wherein the skin layer has a hardness of 70 to 85 IRHD.   The cleaning blade for an electrophotographic copying machine according to any one of claims 1 to 3, wherein a thickness of the skin layer is set in a range of 0.1 to 0.5 mm.   The cleaning blade for an electrophotographic copying machine according to any one of claims 1 to 4, wherein a hardness of a portion other than the skin layer is set in a range of 60 to 80 IRHD.

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