KR20050051211A - Electro-conductive rubber roller and electrophotographic imaging apparatus comprising the same - Google Patents

Abstract

The present invention relates to a conductive rubber roller and an electrophotographic image forming apparatus including the same. Specifically, the additive is added to lower the viscosity so as to uniformly disperse, thereby having a uniform resistance and excellent resistance to migration, and a permanent compression set. The present invention relates to a conductive rubber roller and an electrophotographic image forming apparatus including the same.

Description

Electroconductive rubber roller and electrophotographic imaging apparatus comprising the same}

The present invention relates to a conductive rubber roller used in an electrophotographic image forming apparatus. Specifically, the additive is added by lowering the viscosity to uniformly disperse the additive, and thus have excellent resistance to migration and excellent permanent strain. It relates to a conductive rubber roller characterized in that the low, and an electrophotographic image forming apparatus comprising the same.

FIG. 1 schematically shows an example of a conventional electrophotographic image forming apparatus, and its operation is as described below. That is, after the photosensitive member 1 is charged by the charging device 6, a latent image is formed on the photosensitive member by image exposure through a laser scanning unit (LSU) 9. The toner 4 is supplied to the developing roller 2 by the toner supply roller 3. The toner supplied to the developing roller 2 is thinned to a uniform thickness by the toner layer regulating device 5, and charged with high friction. The toner that has passed through the toner layer restricting device 5 is developed on an electrostatic latent image formed on the photosensitive member 1, and the developed toner is transferred to the paper by a transfer roller (not shown) and fixed by a fixing unit (not shown). The residual toner 8 after transfer on the photoconductor is also cleaned by the cleaning blade 7.

The conductive rubber rollers used in the electrophotographic image forming apparatus are i) low hardness to obtain a suitable nip width, ii) the conductive rollers in contact are not permanently deformed, i) electric resistance is 10 ^In the semiconductor region of ⁵ to 10 ¹⁰ GPa, i) excellent in abrasion resistance and durability, i) no transfer from the developing roller to the photosensitive member, i) desired charging polarity and charging by friction with toner Amount should be obtained, i) Good releasability with toner, no toner filming on the surface of the developing roller during use, i) Good surface roughness in order to obtain a uniform toner layer on the surface of the developing roller It needs properties such as having.

In order to satisfy the above-mentioned required properties, the conductive rubber roller is added with additives such as conductive fillers such as carbon black and quaternary ammonium salts, crosslinking agents, crosslinking accelerators, anti-aging agents and foaming agents, and are excellent by uniform charging and uniform application of toner. In order to obtain an image, these additives must be uniformly dispersed in the conductive rubber roller.

However, rubber is difficult to achieve uniform dispersion of additives as a high-viscosity polymer of hundreds of thousands or more, so at present it is possible to use plasticizers or low molecular weights in order to lower the hardness of the rubber and to make the dispersion of additives uniform to obtain uniform resistance. It is a situation that a method of using liquid rubber has been developed.

As a method of using a plasticizer, a method of using a low molecular weight plasticizer such as phthalic ester or adipic acid ester, a method of using a plasticizer having a molecular weight of 1,000 or more such as adipic acid polyester or sebacic acid polyester or the like has been proposed. .

However, this method of using a plasticizer has a problem in that the added plasticizer is physically or weakly distributed in rubber in the rubber, so that the plasticizer added to the rubber roller surface during long-term use may contaminate the photoconductor to obtain a good image. This plasticizer increases the hardness of the rubber and causes cracks on the rubber surface, thereby degrading durability and increasing the permanent compression strain.

Moreover, as a method of using a low molecular weight liquid rubber, a low molecular weight epichlorohydrin rubber and a low molecular poly in rubber | gum, such as an acrylonitrile butadiene rubber (NBR), an epichlorohydrin type rubber, ethylene propylene diene rubber, a butyl rubber, etc. The method of adding butadiene, liquid acrylonitrile butadiene rubber, liquid polyisoprene, etc. is proposed.

However, such a method of using liquid rubber also has a problem in that the stickiness of the rubber is increased and the adhesion to the electrophotographic photosensitive member is increased. Moreover, in the case of using the liquid rubber, there is a problem that the permanent compression strain is increased when the low-viscosity liquid polymer that does not participate in the crosslinking is added to the rubber. When the permanent compression strain is increased, the conductive rubber for the electrophotographic image forming apparatus is increased. Since the roller is in contact with the electrophotographic photosensitive member under a constant load, the charging roller is unable to uniformly charge the photosensitive member, and the transfer roller has a problem that the paper conveyability is deteriorated.

The technical problem to be achieved by the present invention is to provide a conductive rubber roller, characterized in that the additives are added by lowering the viscosity to be uniformly dispersed to have a uniform resistance, excellent in resistance to migration, and low permanent compression strain. .

Another object of the present invention is to provide an electrophotographic image forming apparatus including the conductive rubber roller.

The present invention to achieve the above technical problem,

A conductive rubber roller having at least one conductive elastic layer, wherein the conductive elastic layer is

A polymer resin selected from the group consisting of acrylonitrile butadiene rubber, epichlorohydrin rubber, ethylene-propylene diene rubber, styrene butadiene rubber, ethylene propylene rubber, acrylonitrile butadiene isoprene rubber and mixtures thereof; And

Reactive plasticizer represented by the formula (1)

CH ₂ = CHCH ₂ -OOC-R ₁ -COO-CH ₂ CH = CH ₂

In the above formula, R ₁ is a substituted or unsubstituted aliphatic alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted aliphatic alkenylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 12 carbon atoms, Substituents when R ₁ is substituted are a nitro group, an amino group, an alkyl group having 1 to 5 carbon atoms and an alkoxy group having 1 to 5 carbon atoms,

The content of the reactive plasticizer is based on 100 parts by weight of the polymer resin provides a conductive rubber roller, characterized in that 0.1 to 80 parts by weight.

In order to achieve the above another technical problem, the present invention,

An electrophotographic image forming apparatus including the conductive rubber roller is provided.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a conductive rubber roller and an electrophotographic image forming apparatus including the same, wherein the conductive rubber roller includes at least one conductive elastic layer, and the conductive elastic layer includes a polymer resin and a reactive plasticizer.

Polymer resins that can be used in the conductive rubber roller according to the present invention include acrylonitrile butadiene rubber, epichlorohydrin rubber, ethylene-propylene diene rubber, styrene butadiene rubber, ethylene propylene rubber, acrylonitrile butadiene isoprene rubber and their A mixture etc. are mentioned, for example. Among these, epichlorohydrin rubber is excellent in compatibility with an acrylonitrile butadiene rubber.

The acrylonitrile butadiene rubber preferably has an acrylonitrile content of 10 to 35 mol% or less. When the content of acrylonitrile exceeds 35 mol%, the environmental dependence is increased, and when the content of acrylonitrile is less than 10 mol%, there is a problem in that the resistance of acrylonitrile butadiene rubber is increased.

In addition, it is preferable that epichlorohydrin rubber uses the ternary copolymer of ethylene oxide, allyl glycidyl ether, and epichlorohydrin, or the binary copolymer of ethylene oxide and epichlorohydrin. The copolymerization ratio of ethylene oxide in the epichlorohydrin rubber is preferably 38 to 58 mol%. When the copolymerization ratio is less than 38 mol%, it is difficult to obtain a resistance value required for conductive rollers such as a charging roller or a developing roller. It is difficult and if it exceeds 58 mol%, there is a problem that the environmental dependence of the resistance increases.

The conductive elastic layer according to the present invention further comprises 0.1 to 80 parts by weight of the reactive plasticizer represented by Formula 1 based on 100 parts by weight of the polymer resin:

<Formula 1>

CH ₂ = CHCH ₂ -OOC-R ₁ -COO-CH ₂ CH = CH ₂

In the above formula, R ₁ is a substituted or unsubstituted aliphatic alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted aliphatic alkenylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 12 carbon atoms, The substituent in the case where R ₁ is substituted is a nitro group, an amino group, an alkyl group having 1 to 5 carbon atoms and an alkoxy group having 1 to 5 carbon atoms.

Since the reactive plasticizer according to Chemical Formula 1 has a low viscosity like low molecular plasticizers such as phthalic acid esters, it facilitates the dispersion of rubber and additives when kneading, thereby causing irregular resistance of the conductive rollers due to heterogeneous dispersion or partial unvulcanization. The durability problem caused by this can be solved. In addition, when the rubber is vulcanized with a crosslinking agent such as a peroxide in the vulcanization step after kneading, the double bond of the reactive plasticizer also participates in the vulcanization reaction so that the rubber and the plasticizer are chemically bonded.

Thus, while conventional plasticizers are present in the rubber by physical or secondary bonding force, the reactive plasticizers according to the present invention are present in the rubber by strong chemical bonding, and thus have excellent migration resistance and excellent permanentity by uniform crosslinking. It is possible to produce a conductive rubber roller having a compressive strain.

The reactive plasticizer according to the present invention can be synthesized, for example, by esterification of allyl alcohol and dibasic acid, and usable dibasic acids include maleic acid, fumaric acid, glutamic acid, adipic acid, azaline acid and sebacic acid, and the like. Substituted or unsubstituted aliphatic dibasic acids having the same carbon number of 4 to 10; Examples thereof include substituted or unsubstituted aromatic dibasic acids such as phthalic acid and isophthalic acid.

The reactive plasticizer is preferably included 0.1 to 80 parts by weight based on 100 parts by weight of the polymer resin. When the content of the reactive plasticizer is less than 0.1 parts by weight, it is difficult to disperse the additives. When the content of the reactive plasticizer exceeds 80 parts by weight, the hardness of the product increases due to the high degree of crosslinking.

Preferably, the conductive elastic layer according to the present invention further comprises a conductive filler and an anti-aging agent and is foamed by the blowing agent.

Conventionally used conductive fillers may be used as the conductive filler, and non-limiting examples of the conductive filler include an electron conductive agent such as carbon black or an ion conductive agent such as a quaternary ammonium salt. Carbon black, which is an electron conductive agent, preferably has a dibutyl phthalate absorption amount of 50 ml / 100 g or less, and preferably 1 to 100 parts by weight based on 100 parts by weight of the rubber. As the ion conductive agent, quaternary ammonium salts such as trimethyl octadecyl ammonium perchlorate or benzyl trimethyl ammonium chloride are preferable, and 0.01 to 10 parts by weight of the polymer resin is preferably contained.

As the anti-aging agent may be used selected from the group consisting of amine-based antioxidants and phenol-based antioxidants, anti-aging agent is 0.1 to 10 parts by weight based on 100 parts by weight of the polymer resin in consideration of anti-aging effect and contamination It is preferable.

The conductive rubber roller according to the present invention is preferably foamed by a foaming agent, in order to give flexibility to the conductive rubber roller to increase the compression of the rubber roller and the paper and to minimize toner image disturbances, thereby obtaining a good image. It is preferable that the foaming degree by a foaming agent is 20-60 hardness measured with the durometer of E-type of JIS.

As the blowing agent, those selected from the group consisting of azodicarbonamide, 4,4'-oxybis (benzenesulfonylhydrazide) and N, N-dinitrosopentamethylenetetramine (DPT) can be used. In consideration of the temperature and the expansion ratio, it is preferable to include 0.1 to 20 parts by weight based on 100 parts by weight of the polymer resin.

In addition, the conductive rubber roller according to the present invention can be crosslinked using crosslinking agents commonly used in the art, and non-limiting examples of the crosslinking agent include dicumyl peroxide, t-butyl peroxyhexane, benzoyl per Organic peroxides such as oxides or t-butyl peroxybenzoate; brimstone; Thiuram polysulfite; Polyamines such as ethylene diamine, diethylene triamine, triethylene tetraamine, hexamethylene tetraamine or ethylene diamine carbamate; Thioureas such as 2-mercapto imidazoline, 1,3-diethyl thiourea, 1,3-dibutyl thiourea or trimethyl thiourea; And mercaptan triazines such as 2,4,6-trimercapto-1,3,5-triazine or 1-methoxy-3,5-dimercaptotriazine. The crosslinking agent is included in an amount of 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymer resin in consideration of the vulcanization temperature and time.

Crosslinking accelerators A commonly used crosslinking accelerator may also be used, and non-limiting examples of the crosslinking accelerator include zinc oxide; Guanidine-based crosslinking accelerators such as diphenyl guanidine or ditoryl guanidine; Thiazole crosslinking accelerators such as 2-mercapto benzothiazole or dibenzothiazyl disulfide; Sulfenamide-based crosslinking accelerators such as N-ethyl-2-benzothiazylsulfenamide and N-t-butyl-2-benzothiazylsulfenamide; Thiuram crosslinking accelerators such as tetramethyl thiuram disulfide and tetraethyl thiuram disulfide; And aldehyde amine accelerators such as aniline and butylamine. The crosslinking accelerator is preferably included 0.1 to 10 parts by weight based on 100 parts by weight of the polymer resin in consideration of the crosslinking time.

The manufacturing method of the conductive rubber roller which concerns on this invention is as follows.

First, at least one polymer resin selected from the group consisting of acrylonitrile butadiene rubber, epichlorohydrin rubber, ethylene-propylene diene rubber, styrene butadiene rubber, ethylene propylene rubber, acrylonitrile butadiene isoprene rubber and mixtures thereof The mixture is kneaded at a predetermined temperature using a group, and a kneaded product obtained by mixing a conductive filler or the like is kneaded to obtain a rubber composition. The obtained rubber composition is introduced into an extruder and preformed into a tube or the like, and the obtained preform is cut into a predetermined dimension to obtain a preform. The preform is vulcanized to obtain a vulcanized rubber tube, a hot melt adhesive is applied to the outer circumferential surface of the shaft prepared in advance, and then the shaft is inserted into the vulcanized rubber tube obtained above, followed by heat bonding and surface polishing to form a conductive rubber roller of a predetermined size. It can manufacture.

In addition, the present invention provides an electrophotographic image forming apparatus including the conductive rubber roller. The electrophotographic image forming apparatus in which the conductive rubber roller can be used includes a conventional electrophotographic image forming apparatus such as a laser printer, a facsimile machine, a copy machine, and the like, specifically, a laser beam or an LED print head type printer, a facsimile machine, a copier and A multifunction machine etc. are mentioned as an example.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Manufacture of Conductive Rubber Roller

Example 1

50 parts by weight of acrylonitrile butadiene rubber containing 25% acrylonitrile and 50 parts by weight of a hydrin rubber mixture in which epichlorohydrin, ethylene oxide and arylglycidyl ether are mixed in a weight ratio of 40: 56: 4, respectively. The molten rubber is first melted in a preheated Banbury mixer, removed and transferred to an open roller, and then 7 parts by weight of carbon black, 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, 2, 0.5 parts by weight of 2,4-trimethyl-1,2-dihydroquinoline polymer (TMDQ), 1 part by weight of dicumyl peroxide and 20 parts by weight of diallylphthalate were added to disperse uniformly. After aging for 24 hours at room temperature, extruded into a tube at 80 ~ 90 ℃ by single or twin screw extruder, and vulcanized by applying a pressure of 5kgf / cm ² at a temperature of 150 ℃. The obtained vulcanized rubber tube was heat-bonded to the outer circumferential surface of a shaft made of sus material having a diameter of 6 pies and a length of 26 cm using chemlock as an adhesive. The outer diameter of the obtained conductive rubber roller was adjusted to 14 pies, the surface roughness was adjusted to 2 to 3, and the surface friction coefficient was lowered to 0.1 to 0.3 by ultraviolet irradiation to produce a finished conductive rubber roller.

Comparative Example 1

A conductive rubber roller was manufactured in the same manner as in Example 1, except that 20 parts by weight of dioctylphthalate was added instead of diallyl phthalate.

Comparative Example 2

A conductive rubber roller was prepared in the same manner as in Example 1, except that 20 parts by weight of adipic acid-based polyester plasticizer synthesized from adipic acid, ethylene glycol, and propylene glycol was added instead of diallyl phthalate.

Comparative Example 3

A conductive rubber roller was prepared in the same manner as in Example 1, except that 20 parts by weight of liquid acrylonitrile butadiene rubber (NBR) was added instead of diallyl phthalate.

Table 1 below shows the ingredient combination table used to prepare the conductive rubber rollers of Example 1 and Comparative Examples 1 to 3.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 NBR 50 50 50 50 Hydrin rubber 50 50 50 50 Diallyl phthalate 20 Dioctylphthalate 20 Adipic acid plasticizer 20 Liquid NBR 20 Carbon black 7 7 7 7 Zinc oxide 5 5 5 5 Stearic acid One One One One 2,2,4-trimethyl-1,2-dihydroquinoline polymer 0.5 0.5 0.5 0.5 Dicumyl Peroxide One One One One

(Unit: parts by weight)

<Performance test>

For the conductive rubber rollers of Example 1 and Comparative Examples 1 to 3, the ductility resistance, permanent compressive strain, wear resistance, volume specific resistance and roughness were evaluated.

(1) Resistant resistance After leaving the rubber sample in an oven at 100 ° C. for 168 hours, wiping with a soft cloth at room temperature and measuring the weight change before and after standing.

(2) Permanent compressive strain is to make the specimen into a cylinder of 12.7mm thickness and 29mm diameter, sandwich it between space compression devices that are 75% of the specimen thickness, and fix it by applying pressure until the compression plate is completely sealed in space. I was. After 70 hours of aging at 150 ° C., the compression device was removed and the permanent compressive strain was calculated.

Permanent compression set = (Ta-Tb) / (Ta-Tc) × 100

Ta: Raw thickness of the test piece (mm)

Tb: Thickness of the test piece after removing it from the compression device 30 minutes (mm)

Tc: thickness of the space

(3) Wear resistance was performed according to KS M 6624 (1997) using an Acron type wear tester. Specimens are 63.5 mm in diameter, 12.7 mm thick, with a 12.7 mm hole in the center. The test piece was rotated at a speed of 250 ± 5 rpm with a contact angle between the grinder and the test piece at 15 degrees under a pressure load of 45 kg. At this time, the wear rate was expressed as a percentage of the wear after 10,000, 20,000 revolutions.

(4) The volume resistivity was placed on a metal rod rotating at 30 rpm, and a rubber rod was placed on top of the roller. Then, a voltage of -500V was applied to the roller shaft to measure the current value and convert it to a resistance value.

(5) Roughness was measured at the central portion of the rubber roller Ra in the circumferential direction using a Mach measuring equipment.

The evaluation results are shown in Table 2 below.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Performance resistance (% by weight) One 25 5 3 Permanent compression set (%) 8 20 12 15 Wear resistance (% by weight) 0.5 3.2 1.0 1.2 Volume specific resistance (㏁ cm) 5.5 1.2 5.2 6.5 Illuminance (Ra) 0.9 1.1 1.0 0.9

As can be seen from the results of Table 2, the conductive rubber roller according to the present invention has a low migration resistance, a permanent compression strain and abrasion resistance values compared to the conventional conductive rubber rollers, and electrophotographic images even in the volume specific resistance and roughness values. It was in the range suitable for use for the conductive rubber roller for forming apparatuses.

According to the present invention, by lowering the viscosity of the rubber roller to make the additives added uniformly dispersed, the conductive rubber for electrophotographic image forming apparatus, characterized in that it has a uniform resistance, excellent migration resistance, and low permanent compression strain. Rollers may be provided.

1 shows an example of a conventional electrophotographic image forming apparatus.

<Description of Drawing>

1: photosensitive member

2: developing roller

3: toner supply roller

4: toner

5: toner layer regulating device

6: charging device

7: cleaning blade

8: residual toner

9: Laser Scanning Unit (LSU)

Claims (5)

A conductive rubber roller having at least one conductive elastic layer, wherein the conductive elastic layer is At least one polymer resin selected from the group consisting of acrylonitrile butadiene rubber, epichlorohydrin rubber, ethylene-propylene diene rubber, styrenebutadiene rubber, ethylene propylene rubber, acrylonitrile butadiene isoprene rubber and mixtures thereof; And Reactive plasticizer represented by the formula (1) <Formula 1> CH ₂ = CHCH ₂ -OOC-R ₁ -COO-CH ₂ CH = CH ₂ In the above formula, R ₁ is a substituted or unsubstituted aliphatic alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted aliphatic alkenylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 12 carbon atoms, Substituents when R ₁ is substituted are a nitro group, an amino group, an alkyl group having 1 to 5 carbon atoms and an alkoxy group having 1 to 5 carbon atoms, The conductive rubber roller is characterized in that the content of the reactive plasticizer is 0.1 to 80 parts by weight based on 100 parts by weight of the polymer resin. According to claim 1, wherein the acrylonitrile butadiene rubber has an acrylonitrile content of 10 to 35 mol%, the epichlorohydrin rubber is a terpolymer of ethylene oxide, allyl glycidyl ether and epichlorohydrin Or a binary copolymer of ethylene oxide and epichlorohydrin. The conductive rubber roller according to claim 1, further comprising 1 to 100 parts by weight of a conductive filler and 0.1 to 10 parts by weight of an anti-aging agent based on 100 parts by weight of the polymer resin and foamed with a foaming agent. 4. The method of claim 3, wherein the conductive filler is a quaternary ammonium salt selected from the group consisting of carbon black or trimethyl octadecyl ammonium perchlorate and benzyl trimethyl ammonium chloride; The anti-aging agent is a conductive rubber roller, characterized in that selected from the group consisting of amine antioxidants and phenolic antioxidants. An electrophotographic image forming apparatus comprising the conductive rubber roller according to any one of claims 1 to 4.