JP2003262997A - Electrically conductive elastic roll and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrically conductive elastic roll which can improve picture quality of printed matter and which can prolong the life of a device by improving durability of the roll and to provide an image forming device. <P>SOLUTION: In the image forming device 1, toner is stuck onto an electrostatically formed image, the toner is transferred on a form 9 and then is thermally fixed. A toner carrying roll 6 of the image forming device 1 is formed of an electrically conductive rotary shaft 12 and the elastic roll 13 provided at the rotary shaft 12. The elastic roll 13 is formed by impregnating at least inner and outer peripheral surfaces of polyurethane 14 of foamed structure penetrated and supported by the rotary shaft 12 respectively with electrically conductive addition reaction type liquid silicone rubber and hardening. Since the polyurethane 14 of the foamed structure having excellent physical properties is impregnated with electrically conductive liquid silicone rubber having excellent electrification characteristic and then is hardened, the elastic roll 13 can be endowed with excellent physical properties of the urethane foamed body and excellent electric characteristics and environmental characteristics of the silicone rubber. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive elastic roll for OA equipment such as a laser beam printer and a copying machine, and an image forming apparatus.

[0002]

2. Description of the Related Art A conventional image forming apparatus utilizing an electrophotographic system obtains a printed matter by repeating charging, exposing, developing, transferring, cleaning and fixing steps, though not shown. In these steps, a charging roll, a toner transport roll, a developing roll, a photosensitive drum cleaning roll, and a transfer roll are used. Among these, the toner transport roll, the photosensitive drum cleaning roll, and the transfer roll have a foam structure. Conductive elastic rolls are used. The toner carrying roll functions to carry the toner to the developing mechanism in the developing process. As the carrying method, there are a method of using a large foam hole on the outer peripheral surface of the toner carrying roll and a method of using a small amount of static electricity. To be
Further, the conductive elastic roll is molded into a foamed structure using silicone rubber, urethane rubber, NBR, or EPDM.

[0003]

The conventional image forming apparatus is constructed as described above, but in recent years, in order to improve the image quality of printed matter, an apparatus using a toner having a small particle diameter such as a polymerized toner has been developed. Since it is becoming the mainstream, the method of simply using the foaming holes of the toner transport roll without electrically controlling it makes the toner transport amount uneven and adversely affects the image, thus improving the image quality of the printed matter. I can't.

As a method for solving such a problem,
It is possible to control the charge amount by changing the applied voltage or current to the conductive elastic roll and adjust the toner supply amount to keep the print quality constant, but with the request for long-term use of the image forming apparatus, Since the amount of toner used in image forming apparatuses is also increasing, the toner transport rolls also have physical (physical), mechanical structure, environmental, as well as electrical (charging) characteristics.
Durability such as (temperature) characteristics is required. In this respect, the conductive elastic roll made of silicone rubber has a problem that it is lacking in physical properties although it is excellent in electrical characteristics and environmental characteristics. On the contrary, in the case of a conductive elastic roll made of urethane rubber, although it has excellent physical properties, it lacks electrical characteristics and stable charging is difficult.

The present invention has been made in view of the above, and it is possible to improve the image quality of a printed matter, and at the same time, to improve the durability of the roll and to extend the life of the apparatus. An object is to provide a forming device.

[0006]

Means for Solving the Problems The inventor of the present invention can solve the above problems by impregnating (at least the outer peripheral surface of) a foamed structure having excellent physical properties with a conductive liquid silicone rubber having excellent electric characteristics and curing the same. The inventors have found that the above can be solved and completed the present invention. That is, according to the invention of claim 1, in order to achieve the above object, an elastic roll is provided on a conductive rotating shaft, and the elastic roll is made of polyurethane having a foam structure penetratingly supported by the rotating shaft. It is characterized in that it is formed by impregnating a conductive liquid silicone rubber and curing it. The size of the polyurethane cell is 10 to 300 μm, the liquid silicone rubber is an addition reaction type, and the viscosity is 1 to 5 μm.
It is preferably 000 cSt (centistokes).

In order to achieve the above object, in the invention according to claim 3, a toner is attached to an electrostatically formed image, the toner is transferred to a sheet, and thermally fixed.
Claim 1 (attached in a fixed state),
Alternatively, the conductive elastic roll described in 2 is rotatably provided.

The liquid silicone rubber in the claims may be impregnated on a part of the cylindrical polyurethane, that is, on the outer peripheral surface (surface), or on the inner and outer peripheral surfaces of the polyurethane respectively. It is also possible to impregnate all parts of polyurethane. This liquid silicone rubber is preferably diluted with silicone oil and then impregnated as a silicone rubber solution. Further, the conductive elastic roll can be used as various elastic rolls using foamed rubber, specifically, a toner transport roll, a photosensitive drum cleaning roll, a transfer roll, and the like.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described below with reference to the drawings. An image forming apparatus 1 including a laser beam printer according to the present embodiment will be described with reference to FIGS.
As shown in FIG. 3, among the charging roll 2, the toner transport roll 6, the developing roll 7, the transfer roll 8, and the photosensitive drum cleaning roll 10, at least the toner transport roll 6 is a conductive elastic roll 11, and the conductive elastic roll 11 The elastic roll 13 is formed by impregnating and curing a conductive liquid silicone rubber in a polyurethane 14 penetratingly supported by the rotating shaft 12.

The image forming apparatus 1 prints a printed matter by attaching toner to an electrostatically formed image, transferring the toner to the sheet 9 and thermally fixing the toner. To be more specific, the image forming apparatus 1, as shown in FIG.
The printed matter is printed by repeating the charging, exposing, developing, transferring, cleaning, and fixing steps. These steps will be sequentially described. First, in the charging step, the photosensitive drum 3 is charged by being exposed to corona discharge by the charging roll 2 to uniformly charge the surface of the photosensitive drum 3, and in the exposure step. The LED array head 4 illuminates the original, and the reflected light is projected as a bright and dark image on the photosensitive drum 3 by an optical system such as a lens and a mirror to form an electrostatic latent image.

In the developing process, the toner conveyed from the toner cartridge 5 by the toner conveying roll 6 is used to visualize the electrostatic latent image on the developing roll 7, and in the transferring process, the visualized image is transferred to the transfer roll 8. Is electrostatically transferred onto the sheet 9 (for example, A4 copy sheet).
Further, in the cleaning process, the toner remaining on the surface of the photosensitive drum that has been used once is wiped off by the photosensitive drum cleaning roll 10, and in the fixing process, the toner is heated and pressure-fixed on the paper 9.

As shown in FIGS. 2 and 3, the conductive elastic roll 11 has a conductive rotating shaft 12 made of stainless steel or the like.
And an elastic roll 13 integrally formed around the rotary shaft 12, the elastic roll 13 being at least the inner and outer peripheral surfaces 14a and 14b of the polyurethane foam 14 having a cylindrical foam structure that is supported by the rotary shaft 12 so as to penetrate therethrough. Is formed by impregnating and curing a conductive liquid silicone rubber, preferably a diluted conductive silicone rubber solution. The polyurethane 14 is not particularly limited as long as it can be used as the toner transport roll 6, but is formed using a soft urethane sponge or the like having excellent elasticity, and has a cell diameter (minimum unit of foam structure) of the toner. Is formed to have a size of 10 to 300 μm, preferably 50 to 200 μm so as not to adversely affect the conveyance of This is 10
This is because if it is less than μm, the toner conveyance amount becomes insufficient and the image is adversely affected, while if it exceeds 300 μm, the conveyance amount is too large and the image is adversely affected.

In the case of the soft urethane sponge, a soft urethane slab foam cut into a roll shape is usually used. Of course, other than this, an ether polyol foam or an ether polyol foam may be used, but the polyurethane 14 made of an ester polyol foam is preferable. This is because both the ether type and the ester type can obtain a sufficient image for printing, but by comparing them, the ester polyol foam can obtain a higher quality image.

The physical properties of polyurethane 14 are not particularly limited, but in general, density: 15-6
00 kg / m ³ , compressive strength: 10 to 20 kg / 314
m ² , tensile strength: 1.5 to 3.0 kg / cm ² , elongation:
It is preferably 250 to 500%. Also, polyurethane 14
As the raw material of the above, a polyol component and an isocyanate component which are commonly used for producing the flexible polyurethane 14 are used. As the polyol component, for example, hydrocarbon-based polyisobutylene, polyether-based polymer dispersed polyether, polyester-based polyether ester,
Examples include polycarbonate-based polyer carbonates, silicone-based polyols, fluorine-based polyols, and the like.
These may be used alone or in combination of two or more.

The isocyanate component is not particularly limited as long as it is a polyisocyanate having two or more functional groups. For example, 2,4- (or 2,6) tolylene diisocyanate (TDI), orthotoluidine diisocyanate (TODI), naphthylene diisocyanate (NDI),
Xylylene diisocyanate (XDI), 4'-diphenylmethane diisocyanate (MDI), carpositimide modified MDI, polymethylene polyphenyl isocyanate,
Examples thereof include polymeric polyisocyanates, which may be used alone or in combination of two or more.

The liquid silicone rubber is composed of a composition which is liquid or paste-like at room temperature, and hardens when left at room temperature or heated to become an elastic body. This liquid silicone rubber is
Although it is classified into an addition reaction type, a radical reaction type, and a condensation reaction type based on the curing mechanism, it is an addition reaction type because it does not involve moisture during curing and is suitably cured under the curing conditions of Examples described later. A radical reaction type is preferred. In particular, an addition reaction type liquid silicone rubber which is excellent in adhesiveness to the polyurethane 14 and deep-curing property and which is uniformly and rapidly cured by heating is most suitable.

The addition reaction type liquid silicone rubber is generally formed by LIMS (Liquid Injection Moisture).
Lending System) or LSR (Liqu
idSilicone Rubber) and is usually a two-liquid mixed or one-liquid type having a viscosity of about 1 to 5000 cSt, but a viscosity in the range of 1 to 3000 cSt is particularly preferable from the viewpoint of improving workability of impregnation. This addition reaction type liquid silicone rubber uses vinyl group-containing polyorganosiloxane as a main raw material, and a conductive agent, silica-based reinforcing filler, organohydrogenpolysiloxane, reaction control agent, platinum group catalyst, non-functional A base compound is prepared by blending various additives having various characteristics such as silicone oil, and is a type that is cured by heating.

The main raw material polyorganosiloxane is
Although it is not particularly limited as long as it has at least two or more reactive groups in one molecule, a linear dimethylpolysiloxane whose both ends are closed by a vinyldimethylsilyl group is preferable. This polyorganosiloxane is
Those having the following average composition formula, particularly those having an alkenyl group or a hydroxyl group are used. RaSiO (4-a) / 2

Here, R is selected from an alkenyl group, a hydroxyl group, or a monovalent hydrocarbon group, and at least two are an alkenyl group and a hydroxyl group. a is a number from 1.95 to 2.05. Examples of the alkenyl group for R include a vinyl group having 2 to 4 carbon atoms and an allyl group, and examples of the monovalent hydrocarbon group for R other than the alkenyl group and the hydroxyl group include 1 to 1 carbon atoms.
2 is preferable. For example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group and a pentyl group, an allyl group such as a cyclohexyl group, a phenyl group and a benzyl group are applicable.

A conductive agent is added to the addition reaction type liquid silicone rubber, and the conductive agent may be either an electronic conductive agent or an ionic conductive agent. As the electronic conductive agent,
Conductive carbon such as Ketjen black, acetylene black, SAF, ISAF, HAF, FEF, GPF,
Examples thereof include carbon for rubber such as SRF, FT and MI, carbon for ink subjected to oxidation treatment, pyrolytic carbon, graphite, conductive metal oxides such as tin oxide, titanium oxide and zinc oxide, and metals such as nickel and copper.

As the ion conductive agent, perchlorates, chlorates, such as tetraethylammonium, tetrabutylammonium, octadecyltrimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, pendyltrimethylammonium and modified aliphatic dimethylammonium, Hydrochloride, bromate, iodate, borofluoride, lead sulfate, ethyl lead sulfate,
Ammonium salt of lead carboxylate, lead sulfonate, etc., perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride of alkali metal or alkaline earth metal such as lithium, sodium, calcium, magnesium, etc. Examples thereof include hydrogen hydrate, lead trifluoromethyl sulfate, lead sulfonate and the like. As the ionic conductive agent, conductive zinc oxide is most suitable because it has a stable electric resistance value in the semiconductive region (volume resistance value of 10 ³ to 10 ¹¹ Ω).

The addition reaction type liquid silicone rubber is appropriately blended with a diluent or a filler in order to adjust the fluidity and improve the mechanical strength of the molded product. The diluent reduces the viscosity of the liquid silicone rubber and makes it a polyurethane with a foam structure.
4 has the function of facilitating the impregnation of liquid silicone rubber. The diluent is not particularly limited as long as it dissolves a silicone oil type or thinner type silicone rubber. However, since toluene-based compounds adversely affect polyurethane 14, stable polyurethane 14
From the viewpoint of impregnation with the above, a silicone oil-based diluent is preferable. The amount of dilution may be selected so as to show a semiconductive region when the liquid silicone rubber is impregnated into a roll shape.

As the filler, precipitated silica, fumed silica, pyrogenic silica, silica airgel, reinforcing filler such as fumed titanium oxide, crushed quartz, diatomaceous earth, aluminosilicate, iron oxide, calcium carbonate, tetrafluoride. Although a non-reinforcing filler such as ethylene may be used, it may be used as it is or may be surface-treated with an organic silicon compound such as hexamethyldisilazane, trimethylchlorosilane or polymethylsiloxane. The filler is filled in the range of 5 to 200 parts by weight with respect to 100 parts by weight of the liquid silicone rubber. This is because when the amount is less than 5 parts by weight, the dispersion density is too low to obtain the effect, and when it is more than 200 parts by weight, the processability is deteriorated and the general physical properties are deteriorated. is there.

Examples of the reaction control agent blended in the liquid silicone rubber include methylvinylcyclotetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, hydroperoxide and the like. An organic peroxide is mainly used as a vulcanization aid, and a non-reinforcing silica is used as a physical property aid for adjusting hardness and improving heat resistance.

The platinum group catalyst compounded in the liquid silicone rubber functions as an effect promoter for addition reaction. This platinum group catalyst is, for example, chloroplatinic acid, alcohol-modified chloroplatinic acid, platinum supported on a solid catalyst such as platinum black, alumina, silica, carbon, platinum and olefin, ethylene, alcohol, vinyl siloxane. Examples thereof include a complex, each complex of chloroplatinic acid with an olefin, ethylene, alcohol, vinyl siloxane, and the like.

An inorganic filler such as crystallite may be added to the liquid silicone rubber from the viewpoint of adjusting the charge amount, and the liquid silicone rubber may be cured from the viewpoint of suppression of curing at room temperature, storage stability, and improvement of workability. A retarder may be added. Examples of the curing retarder include an acetylene alcohol compound, a vinyl group-containing low molecular weight siloxane compound, diallyl maleate, triallyl isocyanurate, a nitrile compound, and an organic peroxide. Furthermore, the liquid silicone rubber may be blended with a pigment, a heat resistance improver, a flame retardant, a plasticizer, etc., if necessary.

According to the above, elasticity, toughness, wear resistance,
Polyurethane 14 with a foam structure that has excellent physical properties such as aging resistance
In addition, since it is impregnated with an electrically conductive liquid silicone rubber having excellent charging characteristics and cured, it is possible to inexpensively have the excellent physical properties of urethane foam and the excellent electrical characteristics, environmental characteristics, heat resistance, etc. of silicone rubber. it can. Therefore, if the conductive elastic roll 11 of the present embodiment is used as a toner transport roll 6 or a transfer roll 8 in a laser beam printer, a copying machine or the like, it is possible to improve the image quality of printed matter and to use the apparatus for a long time.

Further, the cell diameter of polyurethane is 10 to 30.
Since the size is in the range of 0 μm, it does not hinder the toner transportation. Furthermore, since addition reaction type liquid silicone rubber that can be easily handled without any special equipment or technique and does not interfere with moisture at the time of curing is selected to have a viscosity of 1 to 5000 cSt, the workability of impregnation work can be improved. It will be possible to improve. In particular, if the viscosity of the addition reaction type liquid silicone rubber is 1 to 3000 cSt, the workability of the impregnation work can be significantly improved.

[0029]

EXAMPLES Examples of the conductive elastic roll according to the present invention will be described below together with comparative examples. Example 1 Polyurethane having a foam structure having a cell diameter of 100 μm has a diameter of 1
It was processed into a cylindrical shape having a length of 6 mm and a length of 250 mm, and a through hole having a diameter of 5 mm and a length of 250 mm was processed in the center of this polyurethane to form a cylindrical shape. In addition, a diluent consisting of silicone oil [KF manufactured by Shin-Etsu Chemical Co., Ltd.
-96-0.65CS] 20% added and diluted liquid silicone rubber [Shin-Etsu Chemical Co., Ltd., trade name KE-
106] 100 parts by weight of carbon black [trade name HTC-20 manufactured by Chubu Carbon Co., Ltd.] was added to prepare a conductive liquid silicone rubber having a viscosity of 10 cSt.

Next, a cylindrical polyurethane was sufficiently impregnated with a liquid silicone rubber which had been solubilized, and the polyurethane was allowed to stand at room temperature for 30 minutes to 2 hours, and a conductive rotary shaft was inserted into the through hole of the polyurethane. The size of this rotation axis is
The diameter was 6 mm and the length was 300 mm. When the polyurethane and the rotary shaft are integrated in this way, they are baked in a gear oven at 120 ° C. for 30 minutes to 1.5 hours, left to stand at room temperature, and then made into an arbitrary shape with a cylindrical grinder. The conductive elastic roll was manufactured by grinding.

After the conductive elastic roll was prepared, it was set as a transfer roll in an image forming apparatus (laser beam printer) which is a durability tester as shown in FIG. 1, a printing test was conducted, and the results are summarized in Table 1. . In the printing test, black solid printing (printing only black on the entire surface of the paper) is performed.
Printed part is faint when printing 0th sheet (light print)
It was decided to visually check if there was any.

Example 2 Basically the same as in Example 1, but instead of silicone oil as a diluent, it was diluted with thinner [trade name RTV thinner manufactured by Shin-Etsu Chemical Co., Ltd.]. After the conductive elastic roll was produced, a printing test was conducted and the results are summarized in Table 1. Example 3 Basically the same as Example 1, but the cell diameter of polyurethane was set to 20 μm. After the conductive elastic roll was produced, a printing test was conducted and the results are summarized in Table 1.

Example 4 Basically the same as Example 1, but the cell diameter of polyurethane was 250 μm. After making a conductive elastic roll,
A printing test was conducted and the results are summarized in Table 1. Example 5 Basically the same as in Example 1, but the viscosity of the liquid silicone rubber to be impregnated was 1.0 cSt. After the conductive elastic roll was produced, a printing test was conducted and the results are summarized in Table 1.

Example 6 Basically the same as in Example 1, but the viscosity of the liquid silicone rubber to be impregnated was 4500 cSt. After making a conductive elastic roll, print test is conducted and the result is shown in Table 1.
Summarized in. Comparative Example 1 Basically the same as in Example 1, but instead of polyurethane, NR rubber (natural rubber) excellent in tensile strength, abrasion resistance and the like was used. After the conductive elastic roll was produced, a printing test was conducted and the results are summarized in Table 1.

Comparative Example 2 Basically the same as in Example 1, but instead of polyurethane, it was decided to use isoprene rubber which is excellent in uniform quality and impact resilience. After making a conductive elastic roll,
A printing test was conducted and the results are summarized in Table 1. Comparative Example 3 Basically the same as in Example 1, except that the diluent was diluted with toluene instead of silicone oil.
After the conductive elastic roll was produced, a printing test was conducted and the results are summarized in Table 1.

[0036]

[Table 1]

As is clear from Table 1, the electroconductive elastic rolls of Examples 1 to 6 have no or almost no blur in the printed portion, and thus it was confirmed that they can be used as products. On the other hand, the conductive elastic rolls of Comparative Examples 1 to 3 were found to have a slight blur or a large amount of blur in the printed portion, and it was found that it was difficult to use as a product.

[0038]

As described above, according to the present invention, it is possible to improve the image quality of a printed matter, and further, it is possible to extend the life of the apparatus by improving the durability of the roll.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional explanatory view showing an embodiment of a conductive elastic roll and an image forming apparatus according to the present invention.

FIG. 2 is a perspective explanatory view showing an embodiment of a conductive elastic roll according to the present invention.

FIG. 3 is a side view showing polyurethane in an embodiment of a conductive elastic roll according to the present invention.

[Explanation of symbols]

1 Image forming device 2 charging roll 6 Toner transport roll 7 developing roll 8 transfer rolls 9 sheets 10 Photosensitive drum cleaning roll 11 Conductive elastic roll 12 rotation axes 13 Elastic roll 14 Polyurethane 14a inner peripheral surface 14b outer peripheral surface

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/02 101 G03G 15/02 101 4F074 15/08 501 501/08 501A 4J002 501D 15/16 103 15 / 16 103 21/10 21/00 312 F Term (reference) 2H071 BA03 BA43 DA06 DA08 DA09 DA13 2H077 AC04 AD02 AD06 FA13 FA21 FA25 GA03 2H134 GA01 GB02 HA03 HA05 KG03 KG07 KG08 KH01 KH15 2H200 FA02 GA23 GA44 GB15 HA01 HA28 HB12 H28 HB12 H2812 HB47 JA01 JA25 JA26 JA27 MA03 MA04 MA13 MB01 MC01 MC10 MC16 3J103 AA02 AA13 BA41 FA12 FA18 GA02 GA57 GA58 GA60 HA03 HA12 HA20 HA48 HA53 4F074 AA78 AA90 AC02 CC04Z CD20 DA03 DA24 DA59 4J002 CK031 CK041 CP1421 CP051 CP1421

Claims (3)

[Claims] 1. A conductive elastic roll having a conductive rotary shaft provided with an elastic roll, wherein the elastic roll is impregnated with a conductive liquid silicone rubber in polyurethane having a foam structure which is supported through the rotary shaft. ,
A conductive elastic roll formed by curing. 2. A polyurethane cell having a diameter of 10 to 300 μm
2. The conductive elastic roll according to claim 1, wherein the liquid silicone rubber has an addition reaction type and a viscosity of 1 to 5000 cSt. 3. An image forming apparatus in which toner is attached to an electrostatically formed image, the toner is transferred to a sheet, and thermally fixed, the conductive elastic roll according to claim 1 or 2. An image forming apparatus, which is rotatably provided.