JP3020522B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to an electrophotographic apparatus, in which an electrostatic latent image formed on an electrostatic latent image holding member (photoreceptor) is made non-magnetic. A developing device suitable for visualization with a component developer;

(Prior Art) As a developing device for visualizing an electrostatic latent image formed on an electrostatic latent image holding member by using a non-magnetic-component developer, the configuration or operation is shown in FIG. There are known developing devices. That is, the toner 2 put in the toner container 1 is conveyed to the developing roller 5 by the stirrer 3 and the toner supply roller 4. The toner 2 conveyed to the developing roller 5 passes through the toner layer thickness regulating member 6, is thinned and held on the surface of the developing roller 5, and is given a prescribed charge.

In this manner, the electrostatic latent image formed and held on the latent image holding member 7 is developed by the toner carried on the surface of the developing roller 5 using an electric field, and the electrostatic latent image recorded on the latent image holding member 7 is developed. Is a non-magnetic-component developing device for visualizing target information.

Incidentally, the developing roller 5 has a structure in which a part of the developing roller 5 is cut away and shown in perspective. That is, at least the outer peripheral surface has a conductive layer 5a having a resistance value of 10 ¹⁰ Ωcm or less mainly composed of a polyurethane resin or a polyurethane elastomer, and JIS standard K6301 is provided inside the conductive layer 5a.
Hardness of 40 degrees or less, preferably 35 degrees
And an elastic layer 5b made of oil-resistant rubber having a degree of resistance or less. In the figure, reference numeral 5c denotes a metallic roller base, and examples of the oil-resistant rubber forming the elastic layer 5b include EPDM, urethane, silicone, NBR, chloroprene, and the like. Conductive systems are also used.

(Problems to be Solved by the Invention) However, the following disadvantages are recognized in the developing device. That is, at least the surface of the developing roller used in the developing device is coated with a conductive urethane paint to form a required conductive layer. However, since a conductive additive such as a resin or carbon used in the urethane paint is charged to the same polarity as the toner, a sufficient charge amount cannot be consciously given to the toner. For this reason, a toner layer defect and a conveyance defect such as toner spilling and an unevenly deposited toner layer are likely to occur, and a practically sufficient image cannot be obtained in many cases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and a developing apparatus including a developing roller configured to easily and constantly apply a required amount of charge to toner carried / conveyed by the developing roller. The purpose is to provide.

[Means for Solving the Problems] According to the present invention, a developer is supplied to a developing roller having elasticity, and a regulating member forms a thin layer of the developer on the outer peripheral surface of the developing roller and charges the developer. And bringing the developer layer close to or in contact with the electrostatic latent image holding member, depositing the developer on the electrostatic latent image held by the electrostatic latent image holding member, and developing the visible image. In the apparatus, at least the outer peripheral surface of the developing roller contains a coupling agent having an amino group or an amino substituent and a conductive filler, and a coupling agent present in the developing roller is added and blended by an integral blend method. Characterized by being made of polyurethane.

Therefore, the present invention has been made by paying attention to the fact that a negatively chargeable toner is used in the development process and that the toner can be sufficiently charged by positively charging the developing roller.

The coupling agent contained together with the conductive filler on at least the surface of the developing roller included in the developing device according to the present invention is not particularly limited, but is approximately represented by the following structural formula.

(NH ₂ ) m-R′M-RX _{n wherein} M is Si, Ti, Zr, Cr, P, Al, Al-Zr, etc., RX is an alkoxyl group, acetoxy group, amino group,
Hydrolyzable or condensable groups such as halogen groups,
R 'indicates that the group is substituted by NH _2- with a hydrocarbon group, and m and n are numbers from 1 to 3. Although not necessarily applicable to the above structural formula, similar substances can be used as well.

In the compound as the coupling agent, those in which the central metal is Ti, In addition, assuming that the central metal is silicon, And zircon aluminum-based These compounds may be used alone or in combination of two or more.

On the other hand, as the conductive filler contained together with the coupling agent on at least the surface of the developing roller provided in the developing device according to the present invention, carbon black, metal oxide semiconductor (such as titanium oxide, zinc oxide, tin oxide), metal There are powders (copper, nickel, gold, silver, iron, alloys, etc.).

In the present invention, it is preferable that the conductive filler and the coupling agent contained on at least the surface of the developing roller are previously treated as follows. That is, when mixing the conductive filler and the binder solution, a coupling agent is directly added (integral blending method).

Then, 0.01% by weight to 10% by weight, preferably 0.1% by weight to 5% by weight, of the coupling agent is added to the paint.

Means for forming a required conductive layer on the outer peripheral surface of the developing roller, for example, on the surface of an elastic body made of oil-resistant rubber, include a dipping method, a spray method, and a roll method. Here, the thickness of the conductive layer is in the range of 5 μm to 200 μm, preferably 30 μm to 120 μm, and is preferably adjusted to have conductivity.

When adjusting the conductive paint, for example, silica, titanium oxide, talc, mica and the like may be appropriately added and contained for improving the performance.

(Action) According to the present invention, a coating containing a coupling agent containing an amino group or a substituted amino group and a conductive filler is applied on at least the surface of the developing roller to form a required conductive layer. An effective charge can be given to the toner, so that a sharp line image and a uniform solid image can be output. Further, image deterioration with the lapse of time due to a filming phenomenon in which the toner adheres to the developing roller is eliminated, and the required performance of the developing device can be maintained for a long time.

The chargeability of the paint for forming the conductive layer can be measured with an electrostatic coating surface analyzer (manufactured by Toshiba Chemical Co., Ltd.) schematically shown in FIG. For example, the measurement conditions are set to an atmosphere of 25 ° C. and 65%, and a spherical iron powder is used to pour 1.
The measurement was performed at 30 g, a pouring time of 5.0 seconds, a gradient of 60 °, and one sample at five measurement points. In the case of a conductive layer formed from a paint containing a conductive filler and a coupling agent, 80 × 10 ^{−9 was obtained.} In the range of not less than C and not more than 1200 × 10 ^-9 C, in the case of the conductive layer formed from the paint containing only the conductive filler, the chargeability is clearly not more than 80 × 10 ^-9 C and not more than 80 × 10 ^-9 C. You can see that it is.

In FIG. 3, 15 is a reference iron powder inlet, 16 is an inclined plate (sample table), 17 is reference iron powder, 18 is a saucer, 19 is an insulating plate, 20 is an electrometer, and 21 is a meter connection terminal. is there.

(Example) 3 g of γ- (2-aminoethyl) aminopropylmethyldimethoxysilane was added to a one-component urethane elastomer (binder) THF: methyl ethyl ketone (MEK) 1: 1.
A mixed solution was added to 77 g of the solution, and 20 g of conductive carbon Ketjen Black EC was added thereto while stirring at a high speed with a homogenizer, followed by dispersion for 30 minutes to obtain a conductive paint.

After applying the conductive paint to a thickness of 80 μm by dipping on the outer peripheral surface of the roller made of urethane rubber, the temperature is 100 ° C.
For 20 minutes in a dryer to prepare a developing roller. The developing roller thus obtained had a surface resistivity of 1 × 10 ⁵ Ω · cm.

Using the developing roller, a developing device similar to the developing device whose main configuration is shown in FIG. 1 was constructed and assembled, and development or image formation was performed by conventional means. That is, a 11 μm toner composed of 92% by weight of a polyester resin, 2% by weight of a low molecular weight polypropylene, 4% by weight of carbon, 2% by weight of a contained dye and 0.5% by weight of an external additive is used as the toner, and the rotation of the latent image holding member (photoconductor is OPC). Was set at a surface speed of 50 mm / sec, uniformly charged to a surface potential of -500 V by corona discharge, and after writing image information with a laser, rotated at a surface speed of 100 mm / sec and applied -200 V The required development was performed by pressing the developing roller against the photosensitive member. The developed powder image was transferred to recording paper by a 6 kV direct current corona discharge, and then thermally fixed.

As a result of the above-described transfer and fixation, a clear line image and a solid image also exhibited a uniform high density state. In addition, the images after the life test of 50,000 sheets retained the same image quality as those in the initial stage without deterioration, and even at high temperature and high humidity (30 ° C., 80%), extremely good images were obtained. .

Comparative Example 1 A conductive paint was prepared by an integral blend method in the same manner as in the above example except that methyltrimethoxysilane was used instead of γ- (2-aminoethyl) aminopropylmethyldimethoxysilane. The coating was applied to the outer peripheral surface of the urethane roller by dipping, dried, and a conductive layer was formed to obtain a developing roller. Using this developing roller, a developing device was assembled in the same manner as in Example 1, and development and image formation were performed under the same conditions. As a result, the reproduction of fine lines was good, but the uniformity of the solid image was extremely poor. .

Comparative Example 2 Using a conductive paint containing only a conductive filler (not including a coupling agent or the like), a developing roller was prepared in the same manner as in the example, and image formation was performed using this developing roller. Although the reproduction of the fine line was good, the uniformity of the solid image was extremely poor.

In the above description, a toner composed of a polyester resin, low-molecular-weight polypropylene, carbon, a gold-containing dye and an external additive is used, but other toners may be used. That is, in the developing device according to the present invention, the binder resin,
Known toners including a colorant, a charge control agent, a wax, an anti-caking agent, and the like can be used.

For example, as the binder resin, polystyrene, poly-
Monopolymers of styrene such as P-chlorostyrene and polyvinyltoluene and substituted products thereof, for example, styrene-P-
Chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acryl Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate Copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Coalescence, styrene-acryloni Riruinjin copolymer, styrene -
Maleic acid copolymer, styrene-esthyl maleate copolymer or the like, or polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate,
Polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorination Paraffin, paraffin wax and the like can be used alone or in combination.

Examples of the coloring agent and the charge control agent include carbon black and various dyes and pigments. As the wax, polyethylene and polypropylene are used. Examples of the anti-caking agent include metal oxides such as hydrophobic silica, aluminum oxide, and titanium oxide; minerals such as mica and myla; and spherical resin particles such as PMMA, Teflon, and styrene.

[Effects of the Invention] As described above, the developing property of the developing roller is significantly improved by forming the conductive layer containing the coupling agent containing the amino group or the substituted amino group and the conductive filler on at least the outer peripheral surface. Is done. Thus, according to the developing device of the present invention including the developing roller, it is possible to always obtain a high-density image with a clear line image and a uniform solid image. Moreover, the production of the developing roller is
Since it can be performed at relatively low cost, it can be said that there are many practical advantages in view of obtaining an image of good quality and maintaining required functions for a long period of time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of a developing device, FIG. 2 is a partially cutaway perspective view showing a configuration of a developing roller, and FIG. 3 is a principle diagram of an electrostatic coating film surface analyzing device. 1 toner container 2 toner 3 stirrer 4 toner supply roller 5 developing roller
5a: conductive layer, 5b: elastic layer, 6: toner layer thickness regulating member, 7: latent image holder (photosensitive drum),
8 Exposure device, 9 Charger, 10 Cleaning unit, 11 Transfer device, 12 Recovery plate, 13 Protection resistor, 14 DC power supply

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masahiro Hosoya 1 Kosuka Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Pref. Toshiba Research Institute, Inc. Address: Toshiba Research Institute Co., Ltd. No. 13 Tokyo Electric Co., Ltd. (56) References JP-A-1-284862 (JP, A) JP-A-61-260257 (JP, A) JP-A-61-260255 (JP, A) JP-A-1 -147478 (JP, A) JP-A-62-203177 (JP, A)

Claims (1)

(57) [Claims] 1. A developer is supplied to an elastic developing roller, and a regulating member forms a thin layer of the developer on the outer peripheral surface of the developing roller and gives an electric charge, and the developer layer holds the electrostatic latent image. A developing device for causing a developer to adhere to the electrostatic latent image held on the electrostatic latent image holding body and developing the visible image by bringing the developer close to or in contact with a body; Characterized by comprising a polyurethane containing a coupling agent having an amino group or an amino substituent and a conductive filler, and wherein the coupling agent present in the developing roller is added and blended by an integral blending method. apparatus.