JP2009122316A - Electrophotographic elastic roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic elastic roller capable securely obtaining satisfactory toner chargeability, toner conveyance, releasability, and so on, thereby obtaining a satisfactory image more securely, by specifying clear indices for adjusting surface roughness of the electrophotographic elastic roller. <P>SOLUTION: The electrophotographic elastic roller is formed by forming an elastic layer around a metal core and forming a surface resin layer on the elastic layer directly or across an intermediate layer. In the elastic roller, the arithmetic average height (Ra) of an outline curve defined by JIS B0601(2001), the average height (Rz) of the outline curve, skewness (Rsk) of the outline curve and the root mean square inclination (RΔq) of the outline curve have the following surface properties: Ra=0 to 2 μm, Rz<20 μm, Rsk>0, and RΔq>0.05. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an elastic roller for electrophotography that is suitably used as a developing roller in an electrophotographic apparatus such as a copying machine or a laser beam printer.

  In electrophotographic apparatuses such as copying machines and laser beam printers, various elastic rollers such as a developing roller, a charging roller, a transfer roller, a toner supply roller, and a cleaning roller are used.

  These elastic rollers are often configured such that one or more resin layers are formed on the surface of the elastic layer. Conventionally, when the resin layer is formed, a predetermined amount of particles of a predetermined particle size is formed in the resin layer. The surface roughness according to a use etc. is provided by means, such as disperse | distributing (patent document 1 etc.).

  In other words, it is important to adjust the surface roughness of an electrophotographic elastic roller, particularly a developing roller and a toner supply roller, in order to obtain good toner chargeability, toner transportability, releasability, and the like. As one measure for adjusting the roughness, a method of dispersing particles in the surface resin layer is known.

  However, when a resin layer is formed on an elastic layer made of urethane foam, for example, a so-called “dirt” in which the properties of the elastic layer are altered by the solvent of the paint forming the resin layer is generated, and the surface roughness is uniformly adjusted. It is difficult to find a clear relationship between the surface roughness and the image, and it is not possible to define a clear index for controlling the roller surface roughness. It was.

JP 2000-330372 A

  The present invention has been made in view of the above circumstances, and it is possible to define a clear index for adjusting the surface roughness of the roller, and to reliably obtain good toner chargeability, toner transportability, releasability, and the like. An object of the present invention is to provide an electrophotographic elastic roller that can more reliably obtain a good image.

  As a result of intensive studies to achieve the above object, the present inventor formed an elastic layer around the cored bar, formed a surface resin layer on the elastic layer directly or via an intermediate layer, and developed. When obtaining an electrophotographic elastic roller such as a roller or a toner conveying roller, the arithmetic mean height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, and the contour curve defined in JIS B 0601 (2001) By adjusting the surface roughness of the roller using the skewness (Rsk) of the toner and the root mean square slope (RΔq) of the contour curve as indices, the toner chargeability, toner transportability, releasability, etc. can be controlled well. It was found that the image can be improved.

Therefore, as a result of further trial and error in order to determine suitable values for these indexes, the arithmetic mean height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, and the skewness (Rsk) of the contour curve. ) And the root mean square slope (RΔq) of the contour curve are adjusted as follows, and it has been found that an electrophotographic elastic roller capable of obtaining a good image can be surely obtained, and the present invention has been completed.
Ra = 0-2 μm
Rz <20 μm
Rsk> 0
RΔq> 0.05

  Accordingly, the present invention relates to an electrophotographic elastic roller in which an elastic layer is formed around a metal core and a surface resin layer is formed directly or via an intermediate layer on the elastic layer. JIS B 0601 (2001) The contour surface has the arithmetic mean height (Ra), maximum contour curve height (Rz), contour curve skewness (Rsk) and contour curve root mean square slope (RΔq) as defined above. An elastic roller for electrophotography is provided.

  According to the elastic roller for electrophotography of the present invention, the arithmetic average height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, and the skewness (Rsk) of the contour curve specified in JIS B 0601 (2001). In addition, the roller surface properties are appropriately controlled by means of the root mean square slope (RΔq) index of the contour curve, and good toner chargeability, toner transportability, releasability, etc. can be reliably obtained, and a good image can be obtained. Can be obtained more reliably.

Hereinafter, the present invention will be described in more detail.
As described above, the electrophotographic elastic roller of the present invention is such that an elastic layer is formed around a cored bar, and a surface resin layer is formed on the elastic layer directly or through an intermediate layer.

  The elastic layer may be a general-purpose rubber such as styrene-butadiene rubber (SBR), nitrile rubber (NBR), or butadiene rubber (BR) depending on the use of the roller; polyester-based or styrene-based thermoplastic elastomer; polyurethane; silicone rubber; Although it can be formed using a known elastic body such as an elastomer such as rubber or a foam, in the present invention, polyurethane is particularly preferably used. Furthermore, polyurethane foam has a low balance between hardness and compression set, and low cost. It is preferably used from the viewpoint of conversion.

  Here, there is no restriction | limiting in particular as a polyurethane, What is necessary is just to have a urethane bond in resin obtained by making a polyol component and an isocyanate component react.

  In this case, examples of the polyol component include polyether polyol, polyester polyol, polymer polyol, polytetramethylene ether glycol, polycarbonate diol, castor oil-based polyol, and the like, and one or more of these can be used. Among these, polyether polyols composed of propylene oxide (PO) and ethylene oxide (EO), and polymer polyols containing polystyrene and / or polyacrylate are particularly preferably used.

  Here, when the elastic layer is a polyurethane foam, it is not particularly limited, but these polyols preferably have an average functional group number of 2.5 to 3, and a hydroxyl value of 20 to 60 mgKOH. It is preferable that the EO content is 1 to 20%. In this way, by setting the average functional group number, hydroxyl value, and EO content of the polyol component within the above ranges, even when an organic solvent is used when forming the surface resin layer described later, it is possible to effectively prevent the elastic layer surface from becoming loose. Therefore, it is possible to adjust the surface roughness satisfactorily by forming the surface resin layer directly without providing an intermediate layer.

  Next, the isocyanate component is not particularly limited, but tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), naphthalene diisocyanate (NDI), norbornene diisocyanate ( NBDI) and modified products thereof can be exemplified, and one or more of these can be used. Particularly, modified TDI, modified MDI, and modified HDI are preferably used. More specifically, polyol modified TDI, polyol-modified MDI, and polyol-modified HDI are more preferably used.

  Here, although not particularly limited, the NCO content of these isocyanates is preferably 1 to 25%, and if the NCO content is less than 1%, the reaction is slow and curing takes time. End up. Further, crosslinking is likely to be insufficient, and unreacted components are likely to exude as a contaminant. On the other hand, if it exceeds 25%, the reaction becomes too fast and it may be difficult to inject into the mold at the time of molding.

  In the polyurethane forming this elastic layer, known additions such as a foam stabilizer, a conductive agent, a crosslinking agent, a foaming agent (water, low-boiling substances, gas bodies, etc.), a surfactant, a catalyst, etc., are necessary. An appropriate amount of the agent can be added.

  Examples of the foam stabilizer include a silicone foam stabilizer (such as a block copolymer of dimethylpolysiloxane and polyether) and a polydimethylsiloxane-polyethylene oxide copolymer.

  As the conductive agent, a known ionic conductive agent or electronic conductive agent can be used. Examples of ionic conductive agents include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (eg, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (eg, stearyltrimethylammonium), benzyltrimethylammonium, and modified fatty acid dimethylethylammonium. Perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, ethyl sulfate, carboxylate, sulfonate, ammonium salt, lithium, sodium, Perchlorates, chlorates, hydrochlorides, bromates, iodates, borofluorides, trifluoromethyl sulfates of alkali metals and alkaline earth metals such as potassium, calcium and magnesium Salts, sulfonates, and the like.

  In addition, as the electronic conductive agent, conductive carbon such as ketjen black and acetylene black; rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; carbon for ink subjected to oxidation treatment, Examples include pyrolytic carbon, natural graphite, and artificial graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; metals such as nickel, copper, silver, and germanium.

  Examples of the catalyst include, for example, organometallic catalysts dibutyltin dilaurate, dibutyltin diacetate, stannous octoate, dibutyltin marker peptide, dibutyltin thiocarboxylate, dibutyltin dimalenate, dioctyltin marker peptide, dioctyltin thiocarboxylate. , Phenylmercury, silver propionate, tin octenoate, amine catalyst triethylamine, N, N, N ′, N′-tetramethylethylenediamine, triethylenediamine, N-methylmorpholine, dimethylaminoethanol, bis (2-dimethylaminoethyl) ) Ether, 1,8-diazabicyclo (5,4,0) -undecene-7 and the like are preferably used. These catalysts may be used alone or in combination of two or more.

  When the elastic layer is formed from the polyurethane foam, the foaming method may be either a mechanical flossing method by foaming by mechanical stirring or the like, or a foaming method using a foaming agent such as water. From the viewpoint of product hardness, a mechanical flossing method in which foaming is performed mechanically is preferably employed.

  Next, the surface resin layer formed on the elastic layer can be formed using a known resin selected according to the use of the roller, for example, urethane resin, acrylic resin, acrylic urethane resin, fluorine Examples thereof include resins and modified products thereof.

  In this surface resin layer, an appropriate additive can be blended according to the use of the roller, for example, an appropriate amount of a conductive agent or a resin curing agent similar to those exemplified for the elastic layer as necessary. Can be added.

  This surface resin layer is usually prepared by dissolving and dispersing the resin and additives in an organic solvent such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), ethyl acetate, butyl acetate, methylcyclohexane (MCH), and isopropyl acetate. It is formed by applying paint. In this case, when the so-called jarring occurs where the surface of the elastic layer is roughened by the organic solvent, an undercoat layer can be formed as an intermediate layer between the surface resin layer and the elastic layer.

  As this undercoat layer, water-based paints are preferably used. Specifically, urethane emulsions, acrylic emulsions, rubber latexes (NB, CR, NBR, etc.), modified products thereof, and two or more kinds thereof are used. A mixture etc. are illustrated. In addition, an appropriate amount of an additive such as a conductive agent can be blended in the undercoat layer as necessary.

  The elastic roller for electrophotography of the present invention has the properties of the roller surface, that is, the surface resin layer surface, the arithmetic average height (Ra) of the contour curve defined in JIS B 0601 (2001), the maximum height of the contour curve ( Rz), the skewness (Rsk) of the contour curve, and the root mean square slope (RΔq) of the contour curve are controlled as indices.

  That is, the arithmetic average height (Ra) of the contour curve is Ra = 0 to 2 μm, preferably 0.5 μm <Ra <1.5 μm, and the maximum height (Rz) of the contour curve is Rz <20 μm, preferably Rz. ≦ 15 μm, more preferably Rz ≦ 10 μm, the skewness (Rsk) of the contour curve is controlled to Rsk> 0, and the root mean square slope (RΔq) of the contour curve is controlled to RΔq> 0.05, preferably RΔq> 0.1. Is. If these parameters deviate from the above ranges, the image quality of the image obtained can be obtained without obtaining good toner chargeability, toner transportability, and releasability as a roller for an electrophotographic apparatus, particularly as a developing roller or a toner transport roller. As a result, the object of the present invention cannot be achieved.

  Here, the method for adjusting the (Ra), (Rz), (Rsk), (RΔq) on the roller surface is not limited, and as a result, (Ra), (Rz), (Rsk), (R RΔq) may be in the above range. Specific methods include, for example, a method in which resin particles are dispersed in the surface resin layer to adjust the surface roughness, and the elastic layer surface is polished to give a predetermined surface roughness to the elastic layer surface. Examples of the method include adjusting the (Ra), (Rz), (Rsk), and (RΔq) by forming the surface resin layer.

Here, the resin particles to be mixed and dispersed in the surface resin layer can be appropriately selected according to the type of resin forming the surface resin layer, the thickness of the surface resin layer, and the like. Specific examples include urethane resin particles, acrylic resin particles, melamine resin particles, silicone resin particles, silicone rubber particles, silica particles, glass beads, titanium oxide particles, and the like, and one or more of these are used. be able to. In addition, the shape and size of the particles, the particle size distribution, etc. are appropriately selected and are not particularly limited. Usually, spherical and elliptical spherical particles are preferably used, and the particle size is D ⁵⁰ = 1 to ⁵⁰ μm, It is particularly preferable that D ⁵⁰ = 2-20. By uniformly dispersing an appropriate amount of such resin particles in the surface resin layer, it is possible to adjust the surface roughness of the roller to (Ra), (Rz), (Rsk), (RΔq). .

  The method for polishing the surface of the elastic layer is not particularly limited, but is suitably employed when the elastic layer is a solid elastomer instead of a foam body. Polishing may be performed using a dry type), a polishing tape, a sandpaper, a buff or the like. In this case, the surface roughness of the elastic layer adjusted by polishing is appropriately set according to the material of the elastic layer and the type and thickness of the surface resin layer formed thereon, and is not particularly limited. Is adjusted in the range of Ra = 0 to 3 μm, Rz = 0 to 25 μm, and the thickness of the surface resin layer is set to about 1 to 10 μm, whereby the surface roughness of the roller is set to (Ra), (Rz), ( Rsk) and (RΔq) can be adjusted.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example.

[Examples 1-6 and Comparative Examples 1-10]
Polyurethane foams having the composition shown in Tables 1 to 6 below were subjected to foam molding, and an elastic layer (thickness 4 mm) made of polyurethane foam was formed on the outer periphery of the core metal (8 mmφ). At this time, A liquid in which polyol, foam stabilizer, ionic conductive agent, and catalyst are mixed and B liquid in which isocyanate and carbon black are mixed are prepared in advance, and these A liquid and B liquid are mechanically stirred and mixed. A polyurethane foam elastic layer having a density of 0.64 g / cm ³ was formed on the outer periphery of the cored bar. In addition, all the compounding parts in Tables 1-6 are a mass part.

Next, a coating material having the following composition was applied onto the elastic layer to form a surface resin layer having a thickness of 7 μm, thereby obtaining an electrophotographic elastic roller.
Coating compositions <br/> urethane resin (manufactured by Nippon Polyurethane Co., Ltd. "N5196") 100 parts by weight Carbon black 35 parts by weight urethane particles (manufactured by Dainippon Ink and Chemicals, Inc. "CFB-101", spherical, D ⁵⁰ = 10 [mu] m)
10 parts by weight methyl ethyl ketone 350 parts by weight isocyanate curing agent (“HX” manufactured by Nippon Polyurethanes) 20 parts by weight

  For each of the obtained rollers, the arithmetic mean height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, the skewness (Rsk) of the contour curve, and the square of the contour curve as defined in JIS B 0601 (2001) Average square root slope (RΔq) was measured. The measurement was performed in the longitudinal direction of the roller with a surface roughness meter (contact type). Moreover, the measurement point was set to 40 points at 5 points in the longitudinal direction with 8 points in the circumference. The results are shown in Tables 1-6.

Next, each roller was mounted on a printer cartridge as a developing roller, and this cartridge was set in a laser beam printer “Laser Jet 4050” manufactured by Hewlett-Packard Co., and image tests of the following evaluations 1 and 2 were performed. The results are also shown in Tables 1-6.
Evaluation 1
A black solid was printed, and the image density unevenness of the initial image was evaluated.
Evaluation 2
After printing 5,000 white solid images in an environment of 23 ° C. and 50% RH, the same black solid image as the initial image was printed, and the images were evaluated.

[Example 7 and Comparative Example 11]
A polyurethane foam having the composition shown in Table 7 below is foam-molded in the same manner as in Examples 1 to 6, and a polyurethane foam elastic layer (thickness 4 mm) having a density of 0.64 g / cm ^{3 on} the outer periphery of the core metal (8 mmφ). ) Was formed. In addition, all the compounding parts in Table 7 are a mass part.

Next, a water-based paint having the following composition is applied on the elastic layer to form an undercoat layer having the thickness shown in Table 7, and a surface resin is formed on the undercoat layer in the same manner as in Examples 1-6. The layer was formed to obtain an electrophotographic elastic roller.
Composition of water-based paint 100 parts by mass of chloroprene / methacrylic acid copolymer ("Showprene SRX-1411" manufactured by Showa Denko KK)
Ketjen Black 3.5 parts by mass

  For each of the rollers obtained, as in Examples 1 to 6, the arithmetic mean height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, the contour curve specified in JIS B 0601 (2001) The skewness (Rsk) and the root mean square slope (RΔq) of the contour curve were measured, and an image test was conducted in the same manner. The results are shown in Table 7.

[Comparative Example 12]
An electrophotographic elastic roller was produced in the same manner as in Example 7 except that the surface resin layer was formed directly on the elastic layer without forming the undercoat layer. For the obtained rollers, the arithmetic mean height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, the skewness (Rsk) of the contour curve, and the contour curve as defined in JIS B 0601 (2001). The root mean square slope (RΔq) was measured, and an image test was conducted in the same manner. The results are also shown in Table 7.

[Example 8 and Comparative Example 13]
A polyurethane elastomer having the composition shown in Table 8 below was kneaded and cured to form an elastic layer (thickness 4 mm) made of a solid type polyurethane elastomer on the outer periphery of the core metal (8 mmφ). In addition, all the compounding parts in Table 7 are a mass part.

  Next, the examples except that the surface of the elastic layer was polished to give a surface roughness of Ra = 0.7 to 1.1 and Rz = 7 to 14 on the surface of the elastic layer, and urethane particles were removed thereon. The same resin paint as in Nos. 1 to 6 was applied to form a surface resin layer having the thickness shown in Table 8, and an electrophotographic elastic roller was obtained.

  For each of the rollers obtained, as in Examples 1 to 6, the arithmetic mean height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, the contour curve specified in JIS B 0601 (2001) The skewness (Rsk) and the root mean square slope (RΔq) of the contour curve were measured, and an image test was conducted in the same manner. The results are shown in Table 8.

  As shown in Tables 1 to 8, the arithmetic mean height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, the skewness (Rsk) of the contour curve, and the root mean square slope (RΔq) of the contour curve were optimized. It was confirmed that the rollers of Examples 1 to 8 according to the present invention surely obtained a good image and were excellent in durability.

Claims (12)

In an elastic roller for electrophotography in which an elastic layer is formed around a core metal, and a surface resin layer is formed on the elastic layer directly or via an intermediate layer,
The arithmetic average height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, the skewness (Rsk) of the contour curve, and the root mean square slope (RΔq) of the contour curve defined in JIS B 0601 (2001) An elastic roller for electrophotography characterized by having the following surface properties.
Ra = 0-2 μm
Rz <20 μm
Rsk> 0
RΔq> 0.05   The elastic roller for electrophotography according to claim 1, wherein the surface resin layer is formed by applying an organic solvent-based resin paint.   The elastic roller for electrophotography according to claim 1 or 2, wherein the elastic layer is a polyurethane foam layer formed by a mechanical floss method.   The elastic roller for electrophotography according to claim 3, wherein the elastic layer is a polyurethane foam obtained by mechanically foaming by reacting a polyol component having an average functional group number of 2.5 to 3 and an isocyanate component.   The elastic roller for electrophotography according to claim 3 or 4, wherein the elastic layer is a polyurethane foam obtained by mechanically foaming by reacting a polyol component having a hydroxyl value of 20 to 60 mgKOH and an isocyanate component.   The elastic roller for electrophotography according to any one of claims 3 to 5, wherein the elastic layer is a polyurethane foam obtained by mechanically foaming a polyol component having an EO content of 1 to 20% and an isocyanate component.   The polyol component according to claim 3, wherein one or both of a polyether polyol composed of propylene oxide (PO) and ethylene oxide (EO) and a polymer polyol containing polystyrene and / or polyacrylate are used. The elastic roller for electrophotography according to any one of the above.   The said isocyanate component contains at least 1 sort (s) chosen from modified tolylene diisocyanate (TDI), modified diphenylmethane diisocyanate (MDI), and modified hexamethylene diisocyanate (HDI) having an NCO content of 1 to 25%. The electrophotographic elastic roller according to claim 1.   The elastic roller for electrophotography according to claim 8, wherein the isocyanate component includes any one of polyol-modified TDI, polyol-modified MDI, and polyol-modified HDI.   The elastic roller for electrophotography according to any one of claims 3 to 9, wherein a surface resin layer is formed by directly applying an organic solvent-based resin paint on the elastic layer without forming an intermediate layer.   Particles for adjusting surface properties are blended and dispersed in the surface resin layer, the arithmetic mean height (Ra) of the contour curve, the maximum height (Rz) of the contour curve, the skewness (Rsk) of the contour curve, and the contour curve The elastic roller for electrophotography according to claim 1, wherein the root mean square slope (RΔq) is adjusted.   The elastic roller for electrophotography according to any one of claims 1 to 11, wherein the surface layer is adjusted by polishing the surface of the elastic layer or the intermediate layer, and the surface resin layer is formed thereon.