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(11) | EP 0 655 658 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Friction charge-providing member for positively-chargeable toner |
| (57) A friction charge-providing member for positively-chargeable toner comprising a parent
material and a charge-controlling agent on the surface is disclosed. The charge-controlling
agent is selected from at least one selected from the group consisting of compounds
represented by formula (I) or (II):
wherein A and B each independently represent a hydrogen atom, a halogen atom, an alkoxyl group, a carboxyl group, a hydroxyl group, an ester group, a nitro group, an amino group, an alkylamino group, an alkyl group which may contain a substituent(s) or a phenyl group which may contain a substituent(s); R represents a hydrogen atom, an alkyl group which may contain a substituent(s), a phenyl group which may contain a substituent(s) or a naphthyl group which may contain a substituent(s); m represents an integer 2 to 16; and n represents an integer 4 to 8. |
FIELD OF THE INVENTION
[0001] The present invention relates to a carrier, conveyor member such as development sleeve and doctor blade and other friction charge-providing members for providing friction charge to a dry toner for use in the development of an electrostatic latent image in electrophotography, electrostatic recording, etc.
BACKGROUND OF THE INVENTION
[0002] In the electrophotographic image formation process, an electrostatic latent image is formed on an inorganic photoreceptor such as selenium, selenium alloy, cadmium sulfide and amorphous silicon or an organic photoreceptor comprising a charge-generating agent and a charge-transporting agent. The electrostatic latent image thus formed is developed with a toner, transferred to a paper or plastic film, and then fixed to obtain a visible image.
[0003] Photoreceptors can be charged positively or negatively depending on their configuration. Photoreceptors which allow a printed area to be left as an electrostatic latent image are developed with an oppositely-chargeable toner while those which allow a printed area to be destaticized to effect reversal development are developed with a toner chargeable to the same sign as the printed area. In other words, if a negatively- chargeable photoreceptor is developed with an oppositely-chargeable toner and a positively-chargeable photoreceptor is subjected to reverse development, a positively-chargeable toner is used.
[0004] A toner comprises a binder resin, a colorant, and other additives. In order to have desirable friction chargeability (charging rate, charging level, charging stability, etc.), age stability and environmental stability, the toner normally comprises a charge-controlling agent incorporated therein. Examples of the charge-controlling agent to be incorporated in the positively-chargeable toner include azinic dyes such as nigrosine, basic dyes such as triphenylmethane dyes, laked colors of basic dyes, metal complex dyes comprising quaternary ammonium residues incorporated in its skeletone, quaternary ammonium salts, laked compounds of quaternary ammonium salt, imidazole compounds, vinyl polymers containing an amino group(s), and condensed polymers containing an amino group(s).
[0005] However, dry toners have varieties such as unitary, binary, magnetic and nonmagnetic toners depending on the development process. Charge-controlling agents capable of providing satisfactory chargeability to these toners have been rarely found and put into practical use. Even charge-controlling agents which are possibly fit for practical use preferably appear somewhat on the surface of toner grains to fully exert its effects. This causes the charge-controlling agent to leave from the surface of the toner when the toner grains collide with each other or rub against the carrier or other members, contaminating the carrier or other members.
[0006] As a result, the chargeability of the toner is deteriorated, causing further deterioration thereof with the increase in the duplicated number of sheets. This results in troubles such as image density drop, reproducibility drop and fog formation.
[0007] Therefore, it has been proposed that the toner be provided with chargeability by means of a carrier, conveyor members such as development sleeve and doctor blade or other friction charge-providing members rather than by means of a charge-controlling agent or other additives. In this approach, there is no need to incorporate a charge-controlling agent or other additives in the toner. Thus, there causes no contamination on the carrier or other members, preventing chargeability drop that would result in the deterioration of image quality.
SUMMARY OF THE INVENTION
[0008] It is therefore an object of the present invention to provide a friction charge-providing member for positively-chargeable toner which can be coated on a carrier, conveyor members such as development sleeve and doctor blade or other friction charge-providing members, exhibits a mechanically sufficient strength, can render these conveyor members or friction charge-providing members capable of providing friction charge, exhibits no deterioration of properties even after prolonged use, and can provide a toner with an excellent positive-chargeability.
[0009] The foregoing object of the present invention will become more apparent from the following detailed description and examples.
[0010] As a result of extensive studies, the inventors have invented a friction charge-providing member for positively-chargeable toner which can comprise a carrier, conveyor members such as development sleeve and doctor blade or other friction charge-providing members, exhibits a mechanically sufficient strength, can render these conveyor members or friction charge-providing members capable of providing friction charge, exhibits no deterioration of properties even after prolonged use, and can provide a toner with an excellent positive-chargeability.
[0011] The present invention concerns a friction charge-providing member for positively-chargeable toner comprising a parent material and a charge-controlling agent on the surface of the parent material, at least one selected from the group consisting of compounds represented by formula (I) or (II) being used as the charge-controlling agent:
wherein A and B each independently represent a hydrogen atom, a halogen atom, an alkoxyl group, a carboxyl group, a hydroxyl group, an ester group, a nitro group, an amino group, an alkylamino group, an alkyl group which may contain a substituent(s), or a phenyl group which may contain a substituent(s); R represents a hydrogen atom, an alkyl group which may contain a substituent(s), a phenyl group which may contain a substituent(s), or a naphthyl group which may contain a substituent(s); m represents an integer 2 to 16; and n represents an integer 4 to 8.
BRIEF DESCRIPTION OF THE DRAWING
[0012] By way of example and to make the description more clear, reference is made to the accompanying drawing in which:
Fig. 1 is a sectional view of a typical example of a developing machine employing a friction charge-providing member according to the present invention wherein the reference number 1 shows a toner conveyor member, the reference number 2 shows an elastic blade, the reference number 3 shows a toner feed roller, the reference number 4 shows a toner agitator, and the reference number 5 shows a toner tank.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The preparation of the compound represented by the foregoing general formula (I) or (II) to be incorporated in the friction charge-providing member according to the present invention at least on the surface thereof can be accomplished by any known synthesis methods.
[0014] Compounds represented by the general formula (I) or (II) may be used singly or in combination. These compounds may be used in combination with other charge-controlling agents or other additives. These compounds may be directly used in the form of solution or dispersion in a solvent or may be used in the form of dispersion in a resin. Example of such a solvent include methanol, ethanol, buthanol, acetone, methylethylketone, tetrahydrofuran, toluene, xylene, and dimethylformamide. Examples of such a resin include silicone resin, fluorine resin, polyacrylic ester, polymethacrylic ester, polystyrene, polybutadiene, polyester, polyurethane, polyamide, epoxy resin, chlorinated paraffin, phenolic resin, polycarbonate, and copolymers thereof. These resins may be used singly or in admixture.
[0015] The coating solution obtained by dissolving or dispersing a charge-controlling agent represented by the foregoing general formula (I) or (II) may be coated on the parent material of a friction charge-providing member (e.g., a carrier, and conveyor members such as development sleeve and doctor blade) by dip coating process, spray coating process, brush coating process or the like, and then dried to obtain a friction charge-providing member for positively-chargeable toner according to the present invention. Alternatively, a resin comprising a compound represented by the foregoing general formula (I) or (II) dispersed therein may be formed into a friction charge-providing member such as doctor blade for positively-chargeable toner according to the present invention.
[0016] The coated amount of the charge-controlling agent is preferably from 0.1 to 100 mg per square meter of the parent material of a friction charge-providing member. The amount of the charge-controlling agent contained in the resin to be formed into a friction charge-providing member is preferably from 0.1 to 60 % by weight.
[0017] As the parent material of carrier there can be used a particulate metal such as iron and aluminum, particulate alloy, particulate metallic compound such as particulate metal oxide, particulate glass, particulate ceramic or the like. Any known carriers may be used. As the parent material of sleeve or doctor blade there can be used a metal, alloy or a nonmetallic substance such as plastic and rubber. Any sleeves or doctor blades which have heretofore been used can be used.
[0018] The carrier coated with the charge-controlling agent according to the present invention can be preferably used by being mixed with a toner so that the mixing ratio by weight of the carrier to the toner is from 2/98 to 10/90.
[0019] As the positively-chargeable toner to be used in combination with the charge-providing member according to the present invention there can be used one which has heretofore been used as an electrophotographic toner. In other words, such a positively-chargeable toner is a fine powder comprising carbon black or a colorant such as dye and pigment in a binder resin. The toner may contain a magnetic powder. Further, the toner may comprise an additive for improving the properties thereof, an external processing agent or the like incorporated therein. Moreover, the toner may contain a small amount (0.01 to 5 % by weight) of a positively-chargeable charge-controlling agent.
[0021] The alkoxyl group of A or B is preferably an alkoxyl group having 1 to 12 carbon atoms, the ester group of A or B is preferably an ester group represented by -COOX wherein X is an alkyl group having 1 to 12 carbon atoms or a phenyl group which may contain a substituent(s) (such as an alkyl group having 1 to 12 carbon atoms, an acetyl group, an amino group, a nitro group, a hydroxyl group, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, an acethylamino group, or an alkylamino group), the alkylamino group of A or B is preferably an alkylamino group having 1 to 8 carbon atoms, and the alkyl group which may contain a substituent(s) of A or B is preferably an alkyl group having 1 to 12 carbon atoms which may contain a substituent(s).
[0022] Examples of the substituent for the alkyl group of A or B include a phenyl group, an acetyl group, an amino group, a nitro group, a hydroxyl group, a halogen atom, and an alkoxyl group having 1 to 8 carbon atoms. Examples of the substituent for the phenyl group of A or B include an alkyl group having 1 to 12 carbon atoms, an acetyl group, an amino group, a nitro group, a hydroxyl group, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, and an acethylamino group.
[0023] The alkyl group which may contain a substituent(s) of R is preferably an alkyl group having 1 to 16 carbon atoms which may contain a substituent(s).
[0024] Examples of the substituent for the alkyl group of R include an alkoxyl group having 1 to 8 carbon atoms, a hydroxyl group, a residue of a heterocyclic group having a nitogen atom or an oxygen atom, and a halogen atom. Examples of the substituent for the phenyl group of R include an alkoxyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an acetyl group, a hydroxyl group, a carboxyl group, a nitro group, an alkylamino group having having 1 to 8 carbon atoms, an amino group, and a halogen atom. Examples of the substituent for the naphthyl group of R include a hydroxyl group, a carboxyl group, a nitro group, an alkyl group having 1 to 8 carbon atoms, a carbamoyl group, and a halogen atom.
[0025] Examples of the compound represented by the foregoing general formula (I) or (II) according to the present invention include the following compounds:
[0027] The present invention will be further described in the following examples, but the present invention should not be construed as being limited thereto. The term "parts" as used herein means "parts by weight".
EXAMPLE 1
[0028] 25 parts of Compound No.(1) and 50 parts of a silicone resin were dissolved in 1,000 parts of a 1 : 1 (by weight) mixture of toluene and acetone. 50 parts of the resulting solution was coated on 3,000 parts of a spherical ferrite carrier (average grain diameter: 100 am) by means of a fluidized bed coating machine.
[0029] On the other hand, to 90 parts of styrene-2-ethylhexyl methacrylate were added 5 parts of a polypropylene and 5 parts of carbon black. The mixture was kneaded in a heat-mixer, cooled, coarse-ground, finely ground, and then classified to obtain a black toner having a grain diameter of 10 to 12 µm.
[0030] To 97 parts of the above mentioned carrier were added 3 parts of the toner thus obtained. The mixture was then stirred in a ball mill to obtain a developer. The toner was measured for charge by means of a blow-off powder charge meter. The result was 18 µc/g. With this developer charged in a remodelled commercial duplicating machine, an image was duplicated. As a result, a sharp image was obtained at the initial stage as well as after duplicating 10,000 sheets.
EXAMPLE 2
[0031] 25 parts of Compound No.(9) and 50 parts of styrene-n-butyl methacrylate were dispersed in 1,000 parts of a 1 : 1 (by weight) mixture of toluene and acetone. 50 parts of the resulting dispersion was coated on 3,000 parts of a spherical ferrite carrier (average grain diameter: 100 µm) by means of a fluidized bed coating machine.
[0032] To 97 parts of the carrier thus obtained were added 3 parts of the same toner as used in Example 1. The mixture was then stirred in a ball mill to obtain a developer. The toner was measured for charge by means of a blow-off powder charge meter. The result was 19 uc/g. With this developer charged in a remodelled commercial duplicating machine, an image was duplicated. As a result, a sharp image was obtained at the initial stage as well as after duplicating 10,000 sheets.
EXAMPLE 3
[0033] A developer was prepared in the same manner as in Example 1 except that Spilon Blue 2BNH (available from Hodogaya Chemical Co., Ltd.) as a copper phthalocyanine oil-soluble dye was used instead of carbon black. The toner was measured for charge by means of a blow-off powder charge meter. The result was 24 µc/g. With this toner charged in a remodelled commercial duplicating machine, an image was duplicated. As a result, a sharp image could be obtained at the initial stage as well as after duplicating 10,000 sheets.
EXAMPLE 4
[0034] 25 parts of Compound No.(6) and 50 parts of a silicone resin were dissolved in 1,000 parts of a 1 : 1 (by weight) mixture of toluene and acetone. 50 parts of the resulting solution was coated on 3,000 parts of a spherical ferrite carrier (average grain diameter: 100 am) by means of a fluidized bed coating machine.
[0035] On the other hand, to 89 parts of a low acid value type polyester resin were added 5 parts of a polypropylene and 6 parts of C. I. pigment red 57. The mixture was kneaded in a heat-mixer, cooled, coarse-ground, finely ground, and then classified to obtain a red toner having a grain diameter of 10 to 12 µm.
[0036] To 97 parts of the above mentioned carrier were added 3 parts of the toner thus obtained. The mixture was then stirred in a ball mill to obtain a developer. The toner was measured for charge by means of a blow-off powder charge meter. The result was 22 µc/g. With this developer charged in a remodelled commercial duplicating machine, an image was duplicated. As a result, a sharp image was obtained at the initial stage as well as after duplicating 10,000 sheets.
EXAMPLE 5
[0037] 25 parts of Compound No.(3) and 75 parts of a styrenemethyl methacrylate resin were dissolved in 1,000 parts of a 1 : 1 (by weight) mixture of toluene and acetone. The solution was brush-coated on a toner conveyor member 1 shown in Fig. 1. The toner conveyor member 1 thus treated was then mounted on the development zone.
[0038] On the other hand, to 90 parts of styrene-2-ethylhexyl methacrylate were added 5 parts of a polypropylene and 5 parts of carbon black. The mixture was kneaded in a heat-mixer, cooled, coarse-ground, finely ground, and then classified to obtain a black toner having a grain diameter of 10 to 12 µm. 100 parts of the toner were mixed with 0.2 parts of a hydrophobic colloidal silica with stirring in a Henschel mixer to obtain a toner.
[0039] With this toner charged in the development zone shown in Fig. 1, an image was duplicated. As a result, a sharp image was obtained at the initial stage as well as after duplicating 10,000 sheets. The toner was measured for charge. The result was 16 ac/g.
EXAMPLE 6
[0040] 25 parts of Compound No.(5) and 50 parts of a silicone resin were dissolved in 1,000 parts of a 1 : 1 mixture (by weight) of toluene and acetone. The solution was spray-coated on the toner conveyor member 1 shown in Fig. 1. The coated amount of Compound No.(5) was 4 mg/m2. The toner conveyor member 1 thus treated was then mounted on the development zone.
[0041] With the same toner as prepared in Example 1 charged in the development zone shown in Fig. 1, an image was duplicated. As a result, a sharp image was obtained at the initial stage as well as after duplicating 10,000 sheets. The toner was measured for charge. The result was 17 µc/g.
EXAMPLE 7
[0042] 25 parts of Compound No.(8) and 75 parts of a styrene-methyl methacrylate resin were dissolved in 1,000 parts of a 1 : 1 mixture (by weight) of toluene and acetone.
[0043] The solution was then spray-coated on an elastic blade 2 (made of stainless steel) shown in Fig. 1. The coated amount of Compound No.(8) was 4 mg/m2. The elastic blade 2 thus treated was then mounted on the development zone.
[0044] On the other hand, to 90 parts of a low acid value type polyester resin were added 5 parts of a polypropylene and 5 parts of Spilon Blue 2BNH as a copper phthalocyanine oil-soluble dye. The mixture was kneaded in a heat-mixer, cooled, coarse-ground, finely ground, and then classified to obtain a blue toner having a grain diameter of 10 to 12 µm. 100 parts of the toner were mixed with 0.2 parts of a hydrophobic colloidal silica with stirring in a Henschel mixer to obtain a toner.
[0045] With this toner charged in the development zone shown in Fig. 1, an image was duplicated. As a result, a sharp image was obtained at the initial stage as well as after duplicating 10,000 sheets. The toner was measured for charge. The result was 17 jn.c/g.
EXAMPLE 8
[0046] 25 parts of Compound No.(12) and 50 parts of a silicone resin were dissolved in 1,000 parts of a 1 : 1 mixture (by weight) of toluene and acetone. The solution was brush-coated on the elastic blade 2 (made of stainless steel) shown in Fig. 1. The coated amount of Compound No.(12) was 10 mg/m2. The elastic blade 2 thus treated was then mounted on the development zone.
[0047] With the same toner as prepared in Example 7 charged in the development zone shown in Fig. 1, an image was duplicated. As a result, a sharp image was obtained at the initial stage as well as after duplicating 10,000 sheets. The toner was measured for charge. The result was 15 ac/g.
EXAMPLE 9
[0048] 30 parts of Compound No.(16) and 70 parts of a silicone resin were mixed in a heat-mixer, and then molded into a resin blade. The resin blade thus obtained was then mounted on the elastic blade shown in Fig. 1.
[0049] With the same toner as prepared in Example 7 charged in the development zone shown in Fig. 1, an image was duplicated. As a result, a sharp image was obtained at the initial stage as well as after duplicating 10,000 sheets. The toner was measured for charge. The result was 17 µc/g.
[0050] As mentioned above, the friction charge-providing member according to the present invention can provide an image with the same quality as obtained at the initial stage even after continuous duplicating. The friction charge-providing member according to the present invention causes no change in positive-chargeability and shows little environmental fluctuations, making it possible to obtain a sharp image even after continuous duplicating.
1. A friction charge-providing member for positively-chargeable toner, comprising
a parent material having provided thereon at least one selected from the group consisting
of compounds represented by formula
(I) or (II) as a charge-controlling agent:
wherein A and B each independently represent a hydrogen atom, a halogen atom, an alkoxyl
group, a carboxyl group, a hydroxyl group, an ester group, a nitro group, an amino
group, an alkylamino group, an alkyl group which may contain a substituent(s) or a
phenyl group which may contain a substituent-(s); R represents a hydrogen atom, an
alkyl group which may contain a substituent(s), a phenyl group which may contain a
substituent(s) or a naphthyl group which may contain a substituent(s); m represents
an integer 2 to 16; and n represents an integer 4 to 8.
2. The friction charge-providing member for positively-chargeable toner according
to Claim 1, said parent material is a carrier.
3. The friction charge-providing member for positively-chargeable toner according
to Claim 2, wherein said carrier comprises particulates of metal, alloy, metallic
compound, glass, or ceramic.
4. The friction charge-providing member for positively-chargeable toner according
to Claim 1, wherein said parent material is a conveyor member of a developing machine.
5. The friction charge-providing member for positively-chargeable toner according
to Claim 1, wherein said charge-controlling agent represented by formula (I) or (II)
is provided on the surface of the parent material in an amount of from 1 to 100 mg/m2.
6. The friction charge-providing member for positively-chargeable toner according
to Claim 1, wherein said charge-controlling agent is selected from the group consisting
of the following compounds: