JP2001075451A - Cleaning blade and manufacture of same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning blade for an electrophotographic device with a surface that the friction is satisfactorily minimized thereon, reducing saturation of lubricant material, lubricant particles from the cleaning blade inside, and preventing a photoreceptor drum from being scratched. SOLUTION: As for the cleaning blade 1 made of urethane rubber in the electrophotographic device for cleaning/removing toner remaining on the photoreceptor drum periphery by edge part 2 held in contact with the photoreceptor drum, the device is provided with the cleaning blade that concentration of isocyanurate group on the edge part 3 surface is higher than that of the isocyanurate group at the edge part 3 inside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member used in an electrophotographic process, and more particularly to a cleaning blade for removing toner remaining on a photosensitive drum.
The present invention also relates to a method for manufacturing the cleaning blade.

[0002]

2. Description of the Related Art A cleaning blade is a member used in an electrophotographic apparatus, and has a function of removing unnecessary toner from an outer peripheral surface of a photosensitive drum after a developing process and a transferring process. The cleaning blade is fixed so as to contact the photosensitive drum, and scrapes off unnecessary toner on the rotating photosensitive drum at the contact portion.

[0003] It is important that the surface of the cleaning blade has low friction in order to prevent abrasion of the outer peripheral surface of the photosensitive drum. Conventionally, the following method has been used to reduce the friction of the cleaning blade. (1) A method in which lubricating particles are applied to the vicinity of the blade edge to reduce friction by powder lubrication. However, since the lubricating particles are used in this method, the photosensitive drum surface in contact with the cleaning blade tends to be worn, Further, there is a problem that image deterioration such as a charged memory due to frictional charging of the lubricating particles easily occurs. (2) A method of applying a lubricating oil to the vicinity of the edge of the cleaning blade to reduce the friction. However, in this method, the lubricating oil adheres to the surface of the photosensitive drum and contaminates the photosensitive drum, thereby causing a transfer image to be transferred. There was a problem that deterioration easily occurred. (3) Method of Internally Adding Lubricating Particles to Cleaning Blade to Reduce Friction However, in this method, it is necessary to expose the lubricating particles to the edge surface in order to sufficiently reduce the friction of the cleaning blade, Therefore, it was necessary to add a large amount of lubricating particles. However, the addition of a large amount of lubricating particles, on the other hand, has a problem that the hardness of the blade is greatly increased, and the rubber of the cleaning blade is brittle, the cleaning ability is reduced, and the transferred image is deteriorated. (4) A method of adding a lubricating substance (fluorine compound, silicone compound, etc.) reactive with the raw material of the cleaning blade to form a cleaning blade to reduce friction. This method is also the same as the above-mentioned method (3). In addition, a large amount of lubricant must be added, which causes a problem that the hardness of the cleaning blade is remarkably reduced, plastic deformation is easily generated, and the additive oozes out from the inside of the cleaning blade. There was a point. (5) At the time of molding the cleaning blade, a lubricating substance (fluorine, silicone skeleton, etc.) reactive with the raw material is applied to the mold surface in advance, and the lubricating substance reacts on the cleaning blade surface at the same time as molding to form a lubricating layer. Forming
However, this method is characterized in that a film reacted at the interface can be formed, but most of the reactive lubricating substances have poor compatibility with the urethane rubber and are formed. Since the thickness of the film is small and the number of defects is large, there is a problem that cleaning failure is likely to occur.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a sufficiently low friction surface without applying a lubricating substance or a lubricating oil.
It is an object of the present invention to provide a cleaning blade which causes less oozing of a lubricating substance and a lubricating granule from the inside of the cleaning blade and which does not damage the photosensitive drum.

[0005]

According to the present invention, there is provided a cleaning blade for an electrophotographic apparatus made of urethane rubber for cleaning and removing toner remaining on the outer peripheral surface of a photosensitive drum by an edge contacting the photosensitive drum. Wherein the concentration of the isocyanurate group is higher than the concentration of the isocyanurate group inside the edge portion.

[0006] A cleaning blade of urethane rubber alone, which does not use additives for reducing friction (lubricating oil, lubricating particles, etc.), rotates during the first use of an electrophotographic apparatus in which toner is not adhered to a photosensitive drum. In some cases, the edge of the cleaning blade may be caught in the photosensitive drum, and a failure to be turned up may occur. This is because the contact friction between the photosensitive drum and the cleaning blade becomes larger than usual because the toner has not yet adhered to the surface of the photosensitive drum.

However, the cleaning blade of the present invention, which contains a large amount of isocyanurate groups on the contact surface (edge portion) with the photosensitive drum, has low friction of the material itself, and therefore has a lubricant (lubricating oil, lubricating particles, etc.). Even if it is not used, even when it is used for the first time, it does not roll up and shows stable cleaning performance.

Since the cleaning blade of the present invention does not contain lubricating particles and lubricating oil inside, the contamination of the photosensitive drum due to oil bleed and the phenomenon that the lubricating particles wear the outer peripheral surface of the photosensitive drum are suppressed. Can be

[0009] The concentration of the isocyanurate group at the edge of the cleaning blade may continuously decrease from the surface of the edge.

Here, the term "continuously decreasing" naturally includes a case where the concentration of the isocyanurate group monotonously decreases with the depth. However, the term "continuously decreasing" includes a constant concentration from the surface of the edge portion to a certain depth. This includes the case where the concentration decreases with the depth from the certain depth.

At the edge of the cleaning blade, if the size of the defect caused by abrasion or the like becomes 10 μm or more, toner slips through and causes a cleaning failure. Therefore, it is desirable that the isocyanurate group which lowers the friction of the edge portion surface is present at a certain concentration and deep, but if the concentration of the isocyanurate group is constant at least to a depth of at least 20 μm, the cleaning blade is somewhat worn by long term use. Thus, the initial cleaning performance can be maintained.

The hardness of the cleaning blade is IR
It is desirable that the angle be in the range of 60 to 78 degrees as measured by the HD method (international rubber hardness). If it is 60 to 78 degrees, permanent deformation due to pressure contact can be suppressed. Further, if the angle is not more than 78 degrees, the contacting photosensitive drum will not be damaged.

Further, the present invention is characterized in that the isocyanate which is a raw material forming the isocyanurate group at the edge portion is the same type of isocyanate as a raw material of the urethane rubber forming the cleaning blade. Provide a cleaning blade.

By using a common substance as the isocyanate, the bonding property between the isocyanurate-rich portion on the edge surface of the cleaning blade and the polyurethane layer as the base is further improved.

[0015] The present invention also provides (a) a step of preparing a mixed solution by mixing at least isocyanate, which is a raw material of the isocyanurate group, an isocyanurate trimerization catalyst, and a solvent; and (b) a heated cleaning blade. A step of applying the mixed solution prepared in step (a) to the inner surface of the edge part of the mold to promote isocyanuration and (c) step (b)
And a step of injecting a raw material of urethane rubber into the mold and heating and curing the same.

The method of manufacturing the cleaning blade will be described in more detail. = Process (a) = In order to form a large amount of isocyanurate groups on the contact surface (edge portion) of the urethane rubber cleaning blade with the photosensitive drum, an isocyanuration catalyst (isocyanate trimerization catalyst), isocyanate and A mixed solution containing a solvent is prepared. = Step (b) = The mixed solution prepared in step (a) is applied to the inner surface corresponding to the edge of the mold of the cleaning blade heated and coated with a release agent in advance.

In the mixed solution in which the solvent is volatilized by heating to form a wet thin film, the isocyanuration reaction and the production of polyisocyanate are simultaneously promoted.

As for the heating temperature of the mold, an appropriate temperature can be selected from known techniques.
Is desirable.

The application of the mixed solution to the inner surface of the mold is as follows.
The method can be arbitrarily selected from a method capable of applying a uniform thickness on the inner surface of the mold, but a spray method is suitably used because of simplicity of the procedure. = Step (c) = If isocyanuration proceeds to some extent, a wet thin film of polyisocyanate is formed on the inner surface of the mold, and it has a strength that will not be peeled off by injection of urethane rubber raw materials in the next step For example, a raw material of urethane rubber containing isocyanate, polyol, and various additives such as a chain extender, a cross-linking agent, and a reaction accelerator is injected into the mold and heat-cured.

The injected urethane rubber raw material reacts while being mixed with the isocyanate remaining in the thin film and the trimerization catalyst, so that it is cured together with the urethane reaction and the isocyanurate reaction.

Thus, a hard, low-friction cleaning blade having an isocyanurated surface is obtained. The concentration of the isocyanurate group in the depth direction of the edge portion has a distribution that decreases with the depth, and gradually becomes softer from the surface to the inside. As a result, it is possible to form a cleaning blade having a hard surface and low friction, and a soft and low plastic deformation caused by urethane bonding. Further, the present invention provides a method of manufacturing a cleaning blade used in an electrophotographic apparatus, wherein the same isocyanate as the raw material of the urethane rubber forming the cleaning blade is used as the raw material forming the isocyanurate group in the step (a). Provide a way.

By using the same isocyanate as the raw material of the isocyanurate group with the polyurethane, there is an effect that the isocyanurate-forming reaction can easily proceed with a gradient from the surface to the inside of the blade.

As a system for curing the urethane rubber, there are reaction systems such as a prepolymer method, a semi-one-shot method and a one-shot method, and any of these methods may be employed. Considering the reaction with the film, the more the free isocyanate (the higher the NCO group concentration), the more the isocyanate that reacts, the more the reaction with the isocyanate film to which the trimerization catalyst is added, and the stronger the isocyanate. , Free NCO
The semi-one-shot method and the one-shot method in which the base concentration can be set large are advantageous.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION As the isocyanate trimerization catalyst described above, specifically, metal oxides such as Li ₂ O and (Bu ₃ Sn) ₂ O, hydrite compounds such as NaBH, NaOCH ₃ , KOtBu,
Alkoxide compounds such as borates, N (C ₂ H ₅ ) ₃ ,, N (C
Amine compounds such as H ₃ ) ₂ CH ₂ C ₂ H ₅ , N ₂ C ₆ H ₁₂ , HCO ₂ ^- Na
⁺ , CO ₃ ^-2 (Na ⁺ ) ₂ , PhCO ₂ ^- Na ⁺ / DMF, CH ₃ CO ₂ ^- K ⁺ , (CH ₃ C
O ₂ ⁻ ) ₂ Ca ⁺ , alkaline soaps, alkaline carboxylate salt compounds such as naphthenates, alkaline formate compounds, quaternary ammonium salt compounds such as ((R1) ₃ -NR ₂ OH) ⁺ -OOCR ₃ , combinations As the catalyst, amine / epoxide, amine / amine carboxylate / alkyleneimide are preferably used.

Further, as the isocyanate which is a raw material of the polyurethane and the isocyanurate group, 4,4'-
Aromatic isocyanates such as methylene diisocyanate (MDI) and toluene diisocyanate (TDI), aliphatic isocyanates such as hexamethylene diisocyanate, and cycloaliphatic isocyanates such as hydrogenated MDI are preferred, and 4,4'-methylene diisocyanate is particularly preferred. (MDI)
Is preferred.

As a solvent for dissolving the isocyanate and the isocyanate trimerization catalyst, methyl isobutyl ketone (MIBK), toluene and the like are preferably used.

If isocyanate is selected from the above-mentioned materials, a mixed solution of (1) isocyanate trimerization catalyst: 100 to 10,000 ppm and (2) isocyanate: 10 to 500 g is dissolved in 100 g of the solvent, and the mixture is placed in a mold. Apply to the surface.

Next, regarding the material of the urethane rubber, the same isocyanate as the above-mentioned raw material of the isocyanurate group can be used as the isocyanate.

The polyol which is the other raw material of the polyurethane includes ethylene adipate-based polyester diol, butylene adipate-based polyester diol, hexamethylene adipate-based polyester diol, capdrum octone diol, and ethylene butylene adipate-based polyester diol. Polymerized polyols and polyols obtained by blending these polyols arbitrarily are used.

As the chain extender, 1,4-butanediol, ethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like are used.

As a crosslinking agent, a trifunctional compound such as trimethylolpropane is used. As the reaction promoting catalyst, tin-based dibutyltin dilaurate, stannas octoate, and the like are preferable, and amine-based catalysts include triethylenediamine, tetramethylguanidine, pentamethyldiethylenetriamine, dimethylimidazole, and tetramethylpropanediamine, and are preferably reactive. Triethylenediamine is preferred in that it is fast.

FIG. 1 shows an example of the manufactured cleaning blade. FIG. 1A is a plan view of the cleaning blade viewed from a contact surface side with the photosensitive drum. The carrier 2 is made of stainless steel. A portion of the carrier 2 wider than the blade 1 is a portion to be attached to the electrophotographic apparatus. The blade 1 made of urethane rubber covers the carrier 2. Further, the edge portion 3 in contact with the photosensitive roller is isocyanurated as described above.

[0033]

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

Example 1 As shown in Table 1, 1000 ppm of a quaternary ammonium carboxylate salt-based trimerization catalyst DABCOTMR (Sankyo Air Products) was added to 100 g of methyl isobutyl ketone (MIBK) solvent.
4,4'-methylenephenyl diisocyanate
A mixed solution obtained by mixing 200 g of (MDI) was coated with a release agent in advance, and the support was set at a predetermined position, and 13
The above-mentioned mixed solution is applied to the inner surface of a mold corresponding to a cleaning blade edge surface by a spray method or the like on a mold heated to 0 ° C., the solvent is volatilized, and an MDI containing a trimerization catalyst is added.
Of about 100 μm was formed. Here, the formed thin film is a polyisocyanate containing an isocyanurate group and unreacted MDI.

Subsequently, as shown in Table 1, the following two liquids were prepared as raw materials for urethane rubber. Liquid prepared by mixing 4,4′-methylene diisocyanate (MDI) with ethylene butylene adipate polyester glycol (EABA) having a molecular weight of 1300 so that the NCO group concentration after mixing with other raw materials becomes 18.4 wt%.

Here, the NCO group concentration is defined as the weight% present as active NCO (molecular weight 42) in the prepared solution.
Is shown. A liquid containing EABA as a polyester glycol, 1,4-butadiol (1,4-BD) as a chain extender, trimethylolpropane (TMP) as a crosslinking agent, and triethylenediamine catalyst as a reaction promoting catalyst.

These two liquids were heated to 80 ° C., respectively, mixed at a ratio of 100: 100 by a rotary stirring type mixer, and immediately cured by a semi-one-shot method of casting into a mold.

When the hardness of the formed cleaning blade was measured, it was 74 degrees (IRHD). The coefficient of friction was 1.2 when measured by the coefficient of friction measuring device shown in FIG.

The friction measurement was performed under conditions close to the actual use conditions of the electrophotographic apparatus. Temperature 24.3 degrees, relative humidity 4
Under the condition of 4%, the edge portion of the cleaning blade abuts on the friction surface formed of polyethylene terephthalate (PET) sheet at an angle of 25 degrees, and 3 degrees in the normal direction of the friction surface.
It is pressed against the friction surface with a force of 0 g / cm.

Here, the force applied to the cleaning blade is considered to be that the edge portion and the friction surface are in linear contact (having no area). That is, it is a value obtained by dividing the load (g) applied to the cleaning blade by the contact length (cm) of the cleaning blade.

The friction coefficient was determined from the force required to pull out the friction surface at a constant speed of 10 cm / min in a direction in which the friction surface and the cleaning blade form an acute angle of 25 degrees when viewed from the horizontal direction of the friction surface.

(Example 2) A cleaning blade was produced in the same manner as in Example 1 except that the dry thickness of the mixed solution coating film as a raw material of the isocyanurate group was changed to 50 µm.
Table 1 shows the specifications.

Example 3 A cleaning blade was produced in the same manner as in Example 1 except that the isocyanurate trimerization catalyst was a mixture of potassium octylate and dimethylaminomethylphenol. Table 1 shows the specifications.

(Example 4) The urethane rubber curing system was a prepolymer method, except that the ratio of the two liquids as raw materials of the urethane rubber was 100: 6 and the NCO group concentration was 6.3 wt%. In the same manner as in Example 1, a cleaning blade was produced. Table 1 shows the specifications.

Comparative Example 1 This comparative example is a conventional cleaning blade made of only urethane rubber, which does not perform any processing on the edge portion.

A cleaning blade was prepared in the same manner as in Example 4 except that the isocyanuration treatment was not performed. Table 1 shows the specifications.

(Comparative Example 2) This comparative example is based on a conventional method in which a lubricating substance reacts with the surface of urethane rubber to reduce the friction of the blade.

Instead of the isocyanuration treatment, 200 g of a hydroxy-terminated silicone oil having active hydrogens (Shin-Etsu Chemical: X22-160) having active hydrogen was diluted with 100 g of toluene, and the same method as in the isocyanurate raw material of Example 4 was used. It was applied to a predetermined inner surface of the mold.

The method for forming the urethane rubber is the same as in Example 4.

[0050]

[Table 1] As is clear from Table 1, cleaning blades having lower friction were obtained in Examples 1 to 4 as compared with Comparative Example 1 in which no surface treatment was performed.

Further, the friction is reduced in Examples 1 to 4 as compared with Comparative Example 2 in which silicone is introduced into the surface to reduce friction.

Further, when the cleaning blades of Examples 1 to 4 were rotated while being brought into contact with a polycarbonate-based organic photoreceptor (OPC) drum, the blades could be applied without applying a lubricating powder to the edges as in the prior art. No turnover occurred.

[0053]

According to the present invention, the surface of the cleaning blade made of polyurethane having isocyanurated surface is sufficiently low in friction without applying a lubricating substance or lubricating oil, and the stain from the inside of the additive is obtained. It was possible to obtain a cleaning blade with little protrusion.

Using the cleaning blade of the present invention can avoid the problem that the cleaning blade is turned up at the first use of the electrophotographic apparatus, which is a problem in the prior art.

[Brief description of the drawings]

FIG. 1 is a side view and a plan view of a cleaning blade of the present invention.

FIG. 2 relates to a method of measuring friction of a cleaning blade.

[Explanation of symbols]

 1: Blade 2: Carrier 3: Edge

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 2H034 BF00 BF01 BF03 4J034 CA04 CA05 CB03 CB04 CB07 CC03 DA01 DB04 DC50 DF01 DF12 DF16 DF20 DG03 DG04 DG06 DG08 HA01 HA07 HA11 HC03 HC12 HC17 HC22 HC46 HC52 HC61 KB71 KD12 KE02 QA01 QB15 QD03 RA07 RA14

Claims (5)

[Claims] 1. A cleaning blade of an electrophotographic apparatus made of urethane rubber for cleaning and removing toner remaining on an outer peripheral surface of a photosensitive drum by an edge portion in contact with the photosensitive drum. A cleaning blade characterized by having a higher concentration of isocyanurate groups inside the edge portion. 2. The cleaning blade according to claim 1, wherein the concentration of the isocyanurate group at the edge of the cleaning blade continuously decreases from the surface of the edge. 3. The isocyanate as a raw material forming an isocyanurate group in the edge portion is the same type of isocyanate as a raw material of a urethane rubber forming the cleaning blade. 2. The cleaning blade according to item 2. 4. A step of preparing a mixed solution by mixing (a) at least an isocyanurate group as a raw material of an isocyanurate group, an isocyanurate trimerization catalyst, and a solvent;
(b) applying the mixed solution prepared in step (a) to the inner surface of the edge of the heated cleaning blade mold to promote isocyanuration and (c) after step (b), the mold A method of manufacturing a cleaning blade for use in an electrophotographic apparatus, comprising at least a step of injecting a raw material of urethane rubber therein and heat-curing. 5. The electrophotographic apparatus according to claim 4, wherein the same isocyanate as the raw material of the urethane rubber forming the cleaning blade is used as the raw material for forming the isocyanurate group in the step (a). Manufacturing method of cleaning blade.