JP2728749B2 - 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. The toner carried on the surface of the developing roller 5 in this manner causes the latent image
Is a non-magnetic component developing device that develops an electrostatic latent image formed and held on the latent image holding member 7 to visualize electrostatic information recorded on the latent image holding member 7.

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 Ω · cm or less containing a polyurethane resin or a polyurethane elastomer as a main component, and a JIS plan 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 or a conveyance defect such as toner spilling or an unevenly deposited toner layer is likely to occur, and there is a case where a practically sufficient image cannot be obtained.

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.

[Constitution of the Invention] (Means for Solving the Problems) According to the present invention, a negatively chargeable developer is supplied to a developing roller having elasticity and a conductor layer provided on the outer periphery, and the developing roller is controlled by a regulating member. A thin layer of developer is formed on the outer peripheral surface and an electric charge is applied, and the developer is brought close to or in contact with the electrostatic latent image holding member, and the electrostatic latent image is held on the electrostatic latent image holding member. In a developing device for developing a visible image by attaching a developer, a reactive siloxane oligomer containing an amino group in a molecule is added and contained in at least an outer peripheral surface of the developing roller.

Therefore, the present invention is based on the idea that the developing process according to the present invention uses a negatively chargeable toner, and it is desirable to positively charge the developing roller in order to sufficiently charge the toner. By incorporating a reactive siloxane oligomer into the material constituting the surface of the developing roller, the above problems or inconveniences have been solved. In addition, it was confirmed that, among the reactive siloxane oligomers, a system having an amino group as a reactive functional group was preferable.

The general formula of the reactive siloxane oligomer is (one-end type) (Both end type) Wherein Me is a methyl group, Y is a chemically reactive functional group such as an amino group, R is-(CH ₂ ) ₃ -or -CH _2- ,
n = 1 to 8

The reactive siloxane oligomer which can be used in the present invention is shown below.

As a one-terminal functional dimer, As a bifunctional dimer, (N is 1 to 8, or n has a distribution).

These compounds may be used alone or as a mixture of two or more kinds. It is also possible to improve the mechanical strength and flexibility of the coating film by dispersing it in a conductive urethane-based paint made of a urethane elastomer. It is. By providing a positive charging function, a sufficient charge can be given to the negatively charged toner. Therefore, an image with less fog and excellent solid uniformity can be obtained.

The conductive coating containing the reactive siloxane oligomer containing an amino group in the molecule on the outer peripheral surface of the elastic layer may be uniformly applied to the surface by dipping, spraying, rolling, or the like. The coating is applied to a thickness of 200 μm, preferably 30 μm to 120 μm.

(Action) According to the present invention, an effective charge can be imparted to the toner by using a developing roller containing at least the surface of a reactive siloxane oligomer having an amino group or the like. In other words, since reactive groups such as amino groups show strong electron donating properties, they themselves are positively charged and can easily give a sufficient amount of charge to the toner, so that an image with little fog and excellent solid uniformity is obtained. Can be obtained. Moreover,
The improvement of the mechanical properties of the conductive film itself is also recognized, the life of the developing roller is extended, and the required performance of the developing device itself can be maintained for a long time.

The chargeability of a coating film containing a reactive siloxane oligomer containing an amino group in a molecule constituting the conductive layer is shown in FIG. 3 by an electrostatic coating surface analyzer (manufactured by Toshiba Chemical Co., Ltd.). The result measured in) is more than 80 × 10 ^-9 C and 1200
× is in the 10 ^-9 C following ranges showed good charging property to the charging of the conductive layer of the conventional developing roller was 80 × 10 ^-9 C below. The measurement conditions were as follows: 25 ° C., spherical iron powder in an atmosphere of 65%, 1.30 g per sprinkling amount, 5.0 second sprinkling time, 60 ° gradient, 5 measurement points per sample
The measurement was performed at points, and a sample was prepared by applying a paint to a measurement substrate by dipping.

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

(Example) Example Pentamethyldisiloxaneamine 5 g of a commercially available conductive urethane paint SUPEREX (manufactured by Nippon Miractran Co., Ltd.) was dissolved and thoroughly stirred for 30 minutes. This was diluted with 50 g of tetrahydrofuran (THF) and 50 g of methyl ethyl ketone (MEK) and stirred to prepare a coating. The prepared coating material was applied to the outer peripheral surface of a developing roller (made of urethane rubber) to a thickness of 70 μm by a dipping method, and dried at 100 ° C. for 30 minutes to have a surface resistivity of 1 × 10 ^5.
Ω · cm.

The developing roller manufactured as described above was set in the developing device shown in FIG. That is, 92% by weight of polyester resin, 2% by weight of low molecular weight polypropylene, 4% by weight of carbon, 2% by weight of gold-containing dye and external additives
The electrostatic latent image carrier (photoconductor is OPC) is rotated at a surface speed of 50 mm / sec using a toner with an average particle size of 11 μm consisting of 0.5% by weight, and this is uniformly charged to a surface potential of -500 V by corona discharge. Then, after writing image information with a laser, the developing roller was developed at a surface speed of 100 mm / sec (at twice the speed of the photosensitive member) and -200 V was applied to the developing roller. Then, the developed powder image was transferred to a recording paper by a direct current corona discharge of 6 kV, and was thermally fixed. As a result, a clear solid image of a line image was obtained at a uniform high density. Also, 5
The images after the life test of 10,000 sheets had the same image quality as the initial state without deterioration. High temperature and high humidity (30 ℃, 80%)
, An extremely good image was obtained.

Comparative Example 1 100 g of commercially available conductive urethane paint SUPAREX (manufactured by Nippon Miractran Co.) was dissolved in 50 g of THF and 50 g of MEK, and the mixture was stirred well for 30 minutes to prepare a paint. Using the prepared paint,
A developing roller was prepared by the same means as in the example. The surface specific resistance of this developing roller was 9.0 × 10 ⁴ Ω · cm.

The developing roller is set in the developing device in the same manner as in the above-described embodiment, and the developing and developing is performed under the same conditions as in the above-described embodiment.
As a result of transfer and image formation, the line image was clear, but the solid image was non-uniform and the toner was spilled.

In addition, as the above toner, a polyester resin, low molecular weight polypropylene, carbon, a metal-containing dye and an external additive were used as components, but a binder resin, a colorant, a charge control agent, a wax, an anti-caking agent and the like were used. Any known non-magnetic one-component developer comprising the above additives can be used.
For example, as the binder resin, polystyrene, poly-P
-Homopolymers of styrene such as chlorostyrene, polyvinyltoluene and the like, for example, styrene-P-
Chlorostyrene copolymer, styrene-propylene copolymer, stilene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acryl Methyl 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-isobrene copolymer Coalescence, styrene-acryloni Riruindjin copolymer, styrene -
Maleic acid copolymer, styrene-maleic acid ester copolymer, 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 resins, phenolic resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be used alone or in combination.

Examples of the colorant and charge control agent include carbon black and various facial cleansers, and examples of the wax include polyethylene and polypropylene. Further, 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, by forming a conductive layer containing a reactive siloxane oligomer (particularly having an amino group) on at least the surface of the developing roller, development characteristics (reproduction of fine lines, fog, solid, etc.) ), And the mechanical properties (strength, flexibility, etc.) of the roller itself can also be improved. The reason is considered to be that the amino group and the like have a strong electron-donating property, so that the ability to negatively charge the other party is strong, thereby improving the developing characteristics.

In addition, it is considered that the mechanical strength was improved because the resin molecules were grafted by siloxane bonds. In particular, when a one-terminal type reactive oligomer is used, there is such a tendency.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a configuration of a main part of a developing device, FIG. 2 is a perspective view of a partly cutaway showing an example of a configuration of a developing roller, and FIG. is there. DESCRIPTION OF SYMBOLS 1 ... Toner container 2 ... Toner 3 ... Stirrer 4 ... Toner supply roller 5 ... Toner carrier (developing roller) 5a ... Conductive layer 5b ... Elastic layer 6 ... Toner layer thickness regulating member 6a Spring 7 Latent image holder (photosensitive drum) 8 Exposure device 9 Charger 10 Cleaning unit 11 Transfer device 12 Recovery blade 13 Protection resistor 14 DC Power supply

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shutsu Sato 1 Kosuka Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside Toshiba Research Institute, Inc. (72) Inventor Koji Endo 2-6-1 Nakameguro, Meguro-ku, Tokyo No. Tokyo Electric Co., Ltd. (72) Inventor Yoshimitsu Otaka 2-6-13 Nakameguro, Meguro-ku, Tokyo Tokyo Electric Co., Ltd. (56) References JP-A-1-252975 (JP, A) 1988-81376 (JP, A)

Claims (1)

(57) [Claims] A negatively charged developer is supplied to a developing roller having elasticity and a conductor layer provided on the outer periphery, and a thin layer of the developer is formed on the outer peripheral surface of the developing roller by a regulating member; Developing by applying a charge, bringing the developer close to or in contact with the electrostatic latent image holding member, and attaching the developer onto the electrostatic latent image held by the electrostatic latent image holding member to develop a visible image In the developing device, a reactive siloxane oligomer containing an amino group in a molecule is added and contained in at least an outer peripheral surface portion of the developing roller.