JP3057200B2 - Electrostatic latent image developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-component electrostatic latent image developing apparatus.

[0002]

2. Description of the Related Art Conventionally, as a method of developing an electrostatic latent image using a non-magnetic one-component toner, the toner on a toner carrier (that is, a developing roll) is thinned by a blade-shaped or roll-shaped member, and this method is used. There is known a method of developing a photosensitive member on a photosensitive member having an electrostatic latent image formed thereon. The material used to form the developing roll used in this method generally has a low hardness (rubber hardness of 30 to 40 degrees or less (JISA)) enough to ensure a sufficient contact portion with the photoreceptor. To have appropriate electric characteristics to obtain good development characteristics (10 ⁵ to 10 ¹² Ω ·
cm medium volume resistance is required). Excellent environmental resistance (temperature, humidity) of the above characteristics. Etc. are required.

[0003] By the way, conventionally known developing rolls made of NBR (nitrile butadiene rubber), ECO (epichlorohydrin rubber), urethane rubber, acrylic rubber, chloroprene rubber, etc., satisfy the required characteristics, but satisfy the required characteristics. It is not satisfactory, and has a drawback that its electrical properties are remarkably changed due to changes in temperature and humidity, resulting in poor environmental resistance.

[0004] In view of such points, the inventors have previously proposed a fluorine-based silicone rubber containing a fluorine-based surfactant as a medium-resistance material having low hardness and excellent environmental resistance.

However, the rubber hardness is about 30 degrees (JI
SA) is the lower limit, and a sufficient contact margin between the developing roll and the photoreceptor cannot be obtained, or jitter (horizontal stripes) is generated on an image, and material costs due to the use of a fluorine-based material However, there is a problem that the production roll is large and the production cost is large due to the necessity of surface polishing, and a developing roll in which these are improved has been demanded.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an electrostatic latent image having a medium-resistance developing roll which is excellent in environmental resistance, has very low hardness, has good contact with a photoreceptor, and is economically excellent. It is an object to provide an image developing device.

[0007]

According to the present invention, there is provided an apparatus for developing an electrostatic latent image by a developing roll having a thin layer of non-magnetic one-component toner formed on a surface thereof by a thin layer forming member, wherein the developing roll is An electrostatic latent image development comprising a fluorosilicone polymer having a repeating unit represented by the following formula 1, a dimethylsilicone polymer having a repeating unit represented by the following formula 2, and a foamed elastic layer containing a fluorine-based surfactant. apparatus

Embedded image

Embedded image And the electrostatic latent image developing device is characterized in that at least the surface of the thin layer forming member is made of a member having a rubber hardness of 60 degrees (JISA hardness, specified in JIS K6301) or less. Further, there is provided the electrostatic latent image developing device, wherein resin particles having a particle size of 100 μm or less are scattered or embedded on the surface of the developing roller.

[0008] To solve the above-mentioned problems, the present inventors have
The present inventors have found that it is effective to use a toner carrier having a foamed elastic layer containing a fluorosilicone polymer having a specific structure, and have reached the present invention. That is, when the dimethylsilicone polymer represented by the chemical formula 2 and the fluorine-based surfactant are further added to the fluorosilicone polymer represented by the chemical formula 1, the volume resistance decreases,
It has been found that charge injection can be performed on the toner. Hereinafter, the forming material of the developing roller in the present invention will be described.

The trifluorosilicone polymer having a trifluoropropyl group represented by the above formula 1 used in the present invention has excellent heat resistance and moisture resistance by itself and also has a polar group effect derived from the trifluoropropyl group. It has the characteristics of low volume resistance and high dielectric constant due to its high hardness.Also, it has the advantage of being excellent in environmental resistance because it has small changes in various properties such as hardness and electrical characteristics even when temperature and humidity change. have.

The degree of crosslinking of the dimethylsilicone polymer represented by Chemical Formula 2 used in the present invention can be easily adjusted by changing the amount of methylvinylsiloxane unit in dimethylsiloxane. Here, the crosslink density of the siloxane polymer is R, B.
PRIME, Thermochimica Acta2
6, (1978), 166-174 and "Application Development of Silicone Rubber", Polymer Digest, 1980,
8, can be measured by the method described in p59-60.

That is, a 5 mm × 20 mm sample is cut out from a rubber sheet vulcanized and molded to a thickness of 2 mm and immersed in 50 ml of toluene at room temperature. Then, the weight of the sample containing toluene is measured at appropriate time intervals. When the difference between two measured values measured at intervals of 24 hours is 1% or less of the sample weight, the sample weight is defined as W (g). Next, the sample is air-dried and then dried at 120 ° C. for 3 hours to remove toluene, and the weight Wo (g) is measured. Then, the sample is placed on a platinum boat, heated to 900 ° C. at a heating temperature of 10 ° C./min or less in a nitrogen stream, kept at 900 ° C. for 10 minutes, cooled, and the weight Wf (g) of the remaining sample is measured. I do. Using the above measured values, 1 cc of vulcanized rubber was obtained by the following equation 1.
The number of crosslinks contained per unit No / Vo (mol / cc) is determined and defined as the crosslink density.

(Equation 1)

When the degree of crosslinking of the polymer is less than 4 × 10 ⁻⁴ mol / cc, the toner easily adheres to the thin layer forming member, and white stripes are easily formed in the thin toner layer. Conversely, if the degree of polymer crosslinking exceeds 8 × 10 ⁻⁴ mol / cc, cracking and chipping tend to occur during processing, and a thin layer cannot be formed properly.

As the fluorinated surfactant used in the present invention, any fluorinated compound containing a fluoroalkyl group can be used. In general, nonionic, anionic, cationic and amphoteric surfactants are used. Of the types,
Nonionic materials are preferred in terms of environmental resistance. Further, from the viewpoint that the capacity for lowering the volume resistance is large, those to which an alkylene oxide is added are preferable. The alkylene oxide is preferably ethylene oxide, and the number of repeating units is preferably from 3 to 15.

Commercial products of such a fluorine-based surfactant include, for example, Surflon (manufactured by Asahi Glass Co., Ltd.), Megafac (manufactured by Dainippon Ink and Chemicals, Inc.), F-Top (manufactured by Asahi Glass Co., Ltd.), and Futergeret (manufactured by Neos Co., Ltd.) And Unidyne (manufactured by Daikin Industries, Ltd.).

The developing roller according to the present invention contains a fluorosilicone polymer (Chemical Formula 1), a dimethyl silicone polymer (Chemical Formula 2) and a fluorine-based surfactant as main components as described above. Is from 10 to 900 parts by weight, preferably from 30 to 400 parts by weight, based on 100 parts by weight of the dimethyl silicone polymer. If the amount is less than 10 parts by weight, the volume resistance is hardly reduced sufficiently when a fluorine-based surfactant is added, and if it exceeds 900 parts by weight, the releasability from the toner is reduced.

Although there is no particular limitation on the amount of the fluorine-containing surfactant, the fluorosilicone polymer 100
0.1 to 10 parts by weight, preferably 1 to 5 parts by weight
Parts by weight. If the amount of the fluorine-based surfactant is less than 0.1 part by weight, the effect of lowering the volume resistance is not sufficiently exhibited, and even if it is added in an amount of 10 parts by weight or more, the effect of lowering the volume resistance and improving the environmental resistance are obtained. Is not so improved, and the surface of the developing roll becomes sticky or bleeding development occurs, which is not preferable.

The method of blending the fluorosurfactant with the fluorosilicone polymer can be carried out by a usual method. For example, in the case of a millable type silicone rubber, a liquid type silicone rubber is mixed with a homogenizer using a two-roll or Banbury mixer. Can be carried out with a stirring device.

Further, the foamed elastic layer is based on the form of thin layer formation, and an inorganic filler can be added particularly for controlling mechanical strength. As the inorganic filler, dry silica, wet silica, diatomaceous earth, quartz, titanium oxide, talc, and the like can be used, but dry silica is most preferable because of environmental stability of volume resistance.

The most important feature of the present invention is that the developing roll has a foamed elastic layer made of the above-mentioned forming material. As a result, an ultra-low hardness medium resistance developing roll having environmental resistance, which has not been obtained conventionally, is achieved.

The most preferable method for forming a foam cell using the material is to mix a foaming agent among various methods such as mechanical stirring, by-product gas due to a chemical reaction, impregnation with a liquefied gas or a solvent, press-fitting, and the like. Used. Here, the foaming agent is compounded in a base material, and heated, thereby producing nitrogen, carbon dioxide, ammonia,
A compound that generates a decomposition gas such as hydrogen and forms a cell structure in a base material. In the present invention, an organic blowing agent is preferably used. Specific examples of the foaming agent include azobisisobutyronitrile (AIBN), azodicarbonamide (ADCA), and dinitrosopentamethylenetetramine (DPT). .), But A.I.
I. B. N. Is most preferably used.

The compounding amount of the foaming agent is as follows.
The amount is 0.5 to 5 parts by weight with respect to 00 parts by weight, and the amount can be appropriately adjusted according to the expansion ratio and the material plasticity. The compounding method of the foaming agent can be performed by an ordinary kneading method such as a two-roll or Banbury mixer.

The foamed elastic layer can be formed by either mold foaming or free foaming. However, mold foaming is preferred because it can be used without surface polishing after forming the layer. A typical manufacturing method will be described. A rubber material and a foaming agent are kneaded, and are wound around a core metal whose surface has been previously subjected to a primer treatment using an extrusion molding machine or the like. It is charged into a cylindrical pipe of Al or Ni and fixed. After leaving at a suitable temperature and time (for example, 170 ° C., 30 minutes) depending on a crosslinking agent, a foaming agent, and the like to be used, it is pulled out after cooling.

Further, in order to improve the pull-out property, the surface tackiness, and the chargeability with the toner, it is also possible to wind a rubber material around a cored bar and then scatter and embed resin particles on the surface. Examples of the resin material used for the resin particles include polymethyl methacrylate resin, fluorine resin, vinylidene fluoride resin, silicone resin, epoxy resin, polyamide resin, polystyrene resin, acrylic resin, phenol resin, melamine resin, polyolefin resin, and polyethylene resin. There is. The particle size is preferably 100 μm or less. 1
If it is larger than 00 μm, the unevenness of the developing roll surface is large,
Unevenness occurs in the thin toner layer.

The developing roll manufactured in this way is shown in FIG.
As shown in the representative example, about 1 resin particles are dispersed on the surface.
It has a foamed elastic layer having a skin layer having a thickness of 00 μm to several hundred μm, and can be used without polishing the surface. FIG. 2 shows an example of the most typical developing device of the present invention.
It is preferable that at least the surface of the thin layer forming member is formed of a material having a rubber hardness of 60 degrees or less (defined by JIS K6301). That is, when the material has a rubber hardness of 60 degrees or less, the uniformity of the thin toner layer is good because the material has a followability with the surface of the foamed elastic layer, but when the hardness is higher than 60 degrees, the thin layer becomes uneven.

[0025]

(Production of foamed elastic developing roll)

Foaming elastic layer forming material Fluorosilicone polymer 150 parts by weight Polydimethylsiloxane 100 〃 (Polymer crosslinking degree 1.0 × 10 ^-4 mol / cc) Dry silica 100 系 Fluorosurfactant 5 〃 (DS-401, Daikin Industries, Ltd.) Crosslinking agent 3.5〃 (RC-4, manufactured by Toray Silicone Co., Ltd.) Blowing agent (AIBN) 10〃 (MR-34, manufactured by Toray Silicone Co., Ltd.) SUS core washed with Tricrene Primer (No. 18B, Shin-Etsu Chemical Co., Ltd.) was applied on gold (8 mmφ) and
After air-drying for a time, the above-mentioned forming material is wound by an extruder. Spray silicone resin fine particles (R-902, average particle size 3 μm, manufactured by Toray Silicone Co., Ltd.) on the surface,
Surplus is often wiped off. This is loaded and fixed in an Al pipe having a thickness of 5 mm, and then left in a thermostat at 170 ° C. for 30 minutes. Thereafter, it is taken out, cooled, and the developing roll is pulled out. A developing roll of 20 mmφ was used. Foaming rate is 120
%Met.

Comparative Example [Preparation of Risotto-Type Developing Roll] In Example 1, all except that no foaming agent was used in Example 1 as a developing roll material.
The same as above was used. The same primer as in Example 1 was applied, and the above-mentioned material was wound thereon. Temperature: 170 ° C., time:
After press molding for 10 minutes under the conditions of pressure: 120 kg / m ² , the surface was polished to form a developing roll of 20 mmφ.

Evaluation Method of Developing Roll [Method of Measuring Volume Resistance] A copper foil tape having a width of 2.5 cm is wound around the outer periphery of the developing roll to be used as a main electrode, and a core is used as a counter electrode. Further, a similar tape is wound around a position 1 mm on both sides of the main electrode, and this is grounded to form a guard electrode. The measuring device is a high resistance meter (4329A
High Resistance Meter: YH
Using p), measurement was performed at a direct current of 100 V, and the volume resistance was converted by the following equation. R ': Read value, l: Electrode width (cm) a: Core diameter (8 mmφ) b: Developing roll diameter (20 mmφ) [Rubber hardness] JISA type using constant pressure loader (GS-710, manufactured by Teklock) The hardness was measured. [Image Test] An image test was performed with the developing device of FIG. 2 under the following conditions. Thin layer forming member: 2 types Silicone rubber SH82uD JISA hardness 80 (Toray silicone) Silicone rubber ST485u JISA hardness 50 (Toray silicone) Toner supply roller: Conductive urethane sponge Toner: Negatively charged toner Styrene-acrylic resin 100 parts by weight Chromium-containing monoazo dye 2 {Carbon black 10} Light emitter: opc Line speed: 60 mm / sec An image test was performed by a dot pattern by negative-positive contact development, and unevenness of jitter and a thin toner layer due to contact between the photosensitive member and the developing roller was observed. [Toner charge amount, adhesion amount] Blow-off method The results are shown in Table 1.

[0028]

[Table 1]

[0029]

According to the developing roll having the foamed elastic layer of the present invention, the hardness can be further reduced as compared with the conventional developing roll.
The margin of contact with the photoreceptor is increased, the jitter phenomenon is reduced, and the weight of the material is substantially reduced according to the foaming rate, so that the cost is reduced. Further, by using a thin layer forming member having a rubber hardness of at most 60 degrees or less, the followability to the surface of the developing roll is increased, and the toner thin layer property is improved. Further, there is an effect that a sufficient toner thin layer property can be obtained even with a foaming developing roll whose surface is not polished.

[Brief description of the drawings]

FIG. 1 is a sectional view of a developing roller used in the present invention and a partially enlarged view thereof.

FIG. 2 is an explanatory diagram of the electrostatic latent image developing device of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-166569 (JP, A) JP-A-3-192376 (JP, A) JP-A-2-1881 (JP, A) JP-A-2- 259786 (JP, A) JP-A-3-213883 (JP, A) JP-A-3-251875 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08 501

Claims (3)

(57) [Claims] 1. An apparatus for developing an electrostatic latent image by a developing roll having a thin layer of non-magnetic one-component toner formed on a surface thereof by a thin layer forming member, wherein the developing roll has a repeating unit represented by the following formula (1). An electrostatic latent image developing device comprising a fluorosilicone polymer, a dimethylsilicone polymer having a repeating unit represented by Chemical formula 2, and a foamed elastic layer containing a fluorine-based surfactant. Embedded image Embedded image 2. The electrostatic latent image developing apparatus according to claim 1, wherein at least the surface of the thin layer forming member is formed of a member having a rubber hardness of 60 degrees or less (as defined by JIS K6301). . 3. A particle diameter of 100 μm on a surface of the developing roller.
2. The electrostatic latent image developing device according to claim 1, wherein m or less resin particles are scattered or embedded.