JP5523176B2 - Developer carrier - Google Patents

Description

  The present invention relates to a developer carrier used in an electrophotographic apparatus.

  In recent image forming apparatuses, toner particle size reduction and spheroidization have become mainstream from the viewpoint of high image quality and low consumption. When toner having such a small particle size and spheroid is used, the formation of the toner layer on the developer carrier depends on the usage environment, the physical properties of the toner, and the state of the surface of the developer carrier, and the friction of the toner. It has become difficult to control the charge amount. As a method for controlling the triboelectric charge amount of toner, a method is known in which a resin layer containing a charge control agent is provided on the surface of a developer carrying member.

  Patent Document 1 proposes a developer carrier in which a copolymer containing a vinyl polymerizable monomer and a nitrogen-containing vinyl monomer is contained in a resin layer. With such a configuration, it is possible to increase the triboelectric charge imparting ability for the toner.

  Patent Document 2 proposes a developer carrier having a resin layer made of an acrylic resin having at least a thermosetting resin and a hydroxyl group and a quaternary ammonium base. According to such a configuration, a resin layer having high frictional charge imparting ability and ionic conductivity can be obtained.

  However, in order to improve image quality, in order to develop the electrostatic latent image faithfully, high frictional charge is applied to the toner more quickly, and the toner triboelectric charge distribution is stably and uniformly controlled. It is necessary to do. In addition, since the toner is likely to be charged up under low humidity, it is necessary to quickly impart a high frictional charge to the toner while diffusing the excess charge of the toner more into the developer carrier.

JP 2004-126004 A JP 2010-8878 A

  An object of the present invention is to provide a developer carrying member capable of quickly imparting high triboelectric charge to a toner and suppressing toner charge-up even under high temperature and high humidity and low temperature and low humidity.

The developer carrier according to the present invention is a developer carrier having a base and a resin layer formed on the surface of the base, the resin layer containing an acrylic resin and conductive particles,
The acrylic resin has a unit represented by the following formula (1) and a unit represented by the following formula (2):

[In the formula (1), R ₁ represents a hydrogen atom or a methyl group. ],

[In Formula (2), R ₂ represents a hydrogen atom or a methyl group, and R ₃ represents an alkylene group having 1 to 4 carbon atoms. At least one of R ₄ , R ₅ and R ₆ represents an alkyl group having 6 to 18 carbon atoms, and the remaining group represents an alkyl group having 1 to 5 carbon atoms. A ⁻ represents an anion. ].

  According to the present invention, a high triboelectric charge can be quickly imparted to the toner even under high temperature and high humidity or low temperature and low humidity, and toner charge-up can be suppressed.

1 is a cross-sectional view of a developing device according to the present invention. It is sectional drawing which shows the other example of the developing device which concerns on this invention. It is sectional drawing which shows the further another example of the developing device which concerns on this invention.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments. The developer carrier according to the present invention has at least a base and a resin layer formed on the surface of the base. The resin layer includes an acrylic resin having a predetermined unit and conductive particles.

〔acrylic resin〕
The acrylic resin according to the present invention has a unit represented by the following formula (1) and a unit represented by the following formula (2).

[In the formula (1), R ₁ represents a hydrogen atom or a methyl group. ],

[In Formula (2), R ₂ represents a hydrogen atom or a methyl group, and R ₃ represents an alkylene group having 1 to 4 carbon atoms. At least one of R ₄ , R ₅ and R ₆ represents an alkyl group having 6 to 18 carbon atoms, and the remaining group represents an alkyl group having 1 to 5 carbon atoms. A ⁻ represents an anion. ].

  The reason why the developer carrying member having the resin layer containing the acrylic resin can effectively suppress the charge-up of the toner under low humidity is not clear. However, the present inventors presume that due to the presence of the carboxyl group in the formula (1), the charge of the excessively charged toner is diffused more efficiently into the developer carrier.

On the other hand, the unit represented by the formula (2) included in the acrylic resin according to the present invention gives the resin layer an excellent ability to impart triboelectric charge to the toner. In addition, since the unit represented by the formula (2) has ionic conductivity, the conductivity of the resin layer is improved and toner charge-up can be suppressed. When at least one group selected from R ₄ , R ₅ and R ₆ is an alkyl group having 19 or more carbon atoms, the acrylic resin itself is easily crystallized. As a result, the conductive particles tend to be unevenly present in the resin layer, and the charging stability as the developer carrying member may be relatively lowered. Further, if all of R ₄ , R ₅ and R ₆ are alkyl groups having 5 or less carbon atoms, the ability of the developer carrying member to impart frictional charge to the toner may be relatively lowered.

As the unit represented by the formula (2), one having the following structure is more preferable.
At least one group selected from R ₄ , R ₅ and R ₆ is any long chain alkyl group selected from octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, or tetradecyl. R ₄ , R _5, and R ₆ are the lower alkyl groups having 1 to 5 carbon atoms that are not the long-chain alkyl group. As described above, since a long-chain alkyl group is introduced into at least one of R ₄ , R ₅ , and R ₆ , many units represented by the formula (2) are present on the surface of the resin layer of the developer carrier. Tend to. As a result, there is an effect of improving the ability to impart triboelectric charge to the toner. In particular, R ₄ is any one selected from the group consisting of octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, and tetradecyl, and R ₅ and R ₆ are alkyls having 1 to 5 carbon atoms. Units that are groups are preferred. By being in this range, the ability to impart triboelectric charge to the toner is high, and the conductive particles can exist more uniformly in the resin layer. As a result, the balance between the rapid application of triboelectric charge to the toner and the suppression of charge-up of the toner is further improved.

A ⁻ is an anion in halogens, hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, nitric acid and other inorganic acids, and organic acids such as carboxylic acid and sulfonic acid. From the viewpoint of uniform dispersibility in the solvent, an anion containing a sulfur atom or a halogen atom is preferred.

  The acrylic resin usable in the present invention can be produced by polymerizing a monomer having a quaternary ammonium base. Examples of the monomer having a quaternary ammonium base include monomers represented by the following formula (3).

[Wherein R ₂ represents a hydrogen atom or a methyl group, R ₃ represents an alkylene group having 1 to 4 carbon atoms, and at least one of R ₄ , R ₅ , and R ₆ has 6 to 6 carbon atoms. 18 alkyl groups and other groups each represent an alkyl group having 1 to 5 carbon atoms, and A- represents an anion. ].

As the monomer represented by the formula (3), it is preferable that at least one group of R ₄ , R ₅ and R ₆ is an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, or a tetradecyl group. Either is preferable. In particular, R ₄ is an octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group or tetradecyl group, and R ₅ and R ₆ are alkyl groups having 1 to 5 carbon atoms. More preferred. A ⁻ is an anion in halogens, hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, nitric acid and other inorganic acids, and carboxylic acid, sulfonic acid and other organic acids. From the viewpoint of uniform dispersibility in the solvent, an anion containing a sulfur atom or a halogen atom is preferred.

  In the production process of the acrylic resin usable in the present invention, a known polymerization method such as a bulk polymerization method, a solution polymerization method, an emulsion polymerization method or a suspension polymerization method can be used. The solution polymerization method is preferable from the viewpoint that the reaction can be easily controlled. Solvents used in the solution polymerization method are lower alcohols such as methanol, ethanol, n-butanol, and isopropyl alcohol. In addition, other solvents such as xylene, toluene, ethyl acetate, isobutyl acetate, methyl ethyl ketone, methyl isobutyl ketone, N, N-dimethylformamide, and dimethylformamide may be mixed and used as necessary. The ratio of the solvent and the monomer component is preferably 30 parts by mass or more and 400 parts by mass or less with respect to 100 parts by mass of the solvent from the viewpoint of the reaction rate of the monomer.

  Polymerization of the monomer can be performed, for example, by heating the monomer to 50 ° C. or more and 100 ° C. or less in the presence of a polymerization initiator in an inert gas atmosphere. The following are mentioned as a polymerization initiator. t-butylperoxy-2-ethylhexanoate, cumyl perpivalate, t-butylperoxylaurate, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, di-t-butyl peroxide, t-butyl Cumyl peroxide, dicumyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) ), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate). The polymerization initiators can be used alone or in combination of two or more monomers. Usually, a polymerization initiator is added to the monomer solution to start the polymerization, but a part of the polymerization initiator may be added during the polymerization in order to reduce unreacted monomers. In addition, a method of promoting polymerization by irradiation with ultraviolet rays or an electron beam can be used, and these methods may be combined.

  The amount of the polymerization initiator used is preferably 0.05 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the monomer component from the viewpoint of reducing unreacted monomers and optimizing the reaction rate, and more preferably 0. .1 to 15 parts by mass. The temperature of the polymerization reaction can be set according to the composition of the solvent to be used, the polymerization initiator, and the monomer component. However, the reaction is performed at a temperature of 40 ° C. or higher and 150 ° C. or lower to optimize the reaction rate or to volatilize the solvent. It is preferable at the point which prevents.

  As the monomer of the formula (3), a monomer obtained by quaternizing the monomer represented by the following formula (4) with a quaternizing agent can be used.

[Wherein R ₂ represents a hydrogen atom or a methyl group, R ₃ represents an alkylene group having 1 to 4 carbon atoms, and R ₄ and R ₅ represent an alkyl group. ].

  Examples of the quaternizing agent include the following organic acid compounds. Alkyl halides such as butyl bromide, 2-ethylhexyl bromide, octyl bromide, lauryl bromide, stearyl bromide, butyl chloride, 2-ethylhexyl chloride, octyl chloride, lauryl chloride, stearyl chloride, methyl p-toluenesulfonate, dimethyl sulfate, hydroxynaphthalene Methyl sulfonate. The amount of the quaternizing agent used is 0.8 mol or more and 1.0 mol or less with respect to 1 mol of the monomer represented by the formula (4). This is preferable because the monomer can be quaternized. Quaternization of such a monomer can be performed, for example, by heating the monomer and the quaternizing agent in a solvent at a temperature of 60 ° C. or higher and 90 ° C. or lower.

  It is also possible to obtain a desired quaternary ammonium base-containing polymer by polymerizing the monomer of formula (4) and then quaternizing with the quaternizing agent. In addition, for example, the monomer represented by the formula (4) is polymerized by quaternization with an alkyl halide such as methyl chloride. The obtained quaternary ammonium base-containing polymer is treated with an acid such as p-toluenesulfonic acid or hydroxynaphthalenesulfonic acid to carry out counterion exchange, and is used as a target anionic species. It is also possible.

  The molar ratio of each unit in the acrylic resin is such that b / (a + b) is 0.3 when the number of moles of the unit of formula (1) in the acrylic resin is a and the number of moles of the unit of formula (2) is b. It is preferable that it is 0.9 or more. By setting b / (a + b) to 0.3 or more, the triboelectric charge imparting ability of the acrylic resin is improved, and the ionic conductivity effect due to the quaternary ammonium salt structure is easily enhanced, so that rapid friction against the toner is achieved. The charge imparting ability is improved. By setting b / (a + b) to 0.9 or less, the charge of the toner is easily diffused to the developing carrier, and the toner charge can be suppressed.

The acrylic resin used in the present invention may contain other units in addition to the units represented by the formulas (1) and (2). The other unit may be singular or plural. It is preferable that the content rate of the other unit contained in an acrylic resin is 30 mol% or less of the total unit [mol] which comprises an acrylic resin. By making the content rate of another unit 30 mol% or less, it is easy to obtain the above-mentioned effect by introducing the units represented by the formulas (1) and (2).
[Other resins]
The resin layer constituting the developer carrying member of the present invention may contain a resin other than an acrylic resin, and the durability and environmental stability of the resin layer are improved by including a thermosetting resin. As a thermosetting resin, a phenol resin, a melamine resin, a urea resin, and a benzoguanamine resin are preferable in terms of toughness and durability. Among these, a phenol resin is more preferable because it improves the abrasion resistance of the resin layer, is excellent in environmental stability, and is excellent in compatibility with an acrylic resin.

  When an acrylic resin is mixed with these resins, the acrylic resin can be mixed as a resin solution or as resin particles. When mixing as acrylic resin particles, in order to make the presence of the resin particles in the resin layer uniform, the mass average particle diameter (D4) of the resin particles is preferably 5 μm or less.

[Conductive particles]
In the present invention, in order to adjust the resistance value of the resin layer, the following conductive particles are contained in the resin layer. Examples of the material of the conductive particles include metals, conductive metal oxides, and conductive carbon black. You may use the said electroconductive particle in mixture of 2 or more types. Moreover, as for the compounding quantity of electroconductive particle, 20 to 100 mass parts is preferable with respect to 100 mass parts of resin total amount. By setting this range, the resistance value can be set to a desired level without impairing the strength of the resin layer. In the present invention, the volume resistance value of the resin layer on the surface of the developer carrying member is 10 ⁻¹ Ω · cm or more and 10 ⁴ Ω · cm or less.

[Roughness imparting particles]
In the present invention, irregularity-imparting particles may be added in order to make the surface roughness uniform and maintain an appropriate surface roughness in the resin layer. As the irregularity imparting particles, spherical particles are preferable. By using spherical particles, a desired surface roughness can be obtained with a smaller addition amount, and an uneven surface having a uniform surface shape can be obtained. Further, even when the resin layer is worn, the change in the surface roughness of the resin layer is small, and the change in the toner layer thickness on the developer carrying member hardly occurs.

  Although it does not specifically limit as uneven | corrugated provision particle | grains, Specifically, the following are mentioned. Rubber particles such as EPDM, NBR, SBR, CR, silicone rubber; Elastomer particles such as polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, polyamide-based thermoplastic elastomer (TPE); PMMA, urethane resin, fluororesin, silicone Resin particles such as resin, phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, polyacrylonitrile resin; oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide Conductive particles such as carbonized particles, resin particles subjected to conductive treatment, and other particulates of organic compounds such as imidazole compounds.

[Substrate]
Examples of the substrate of the developer carrying member used in the present invention include members such as a cylindrical member, a columnar member, and a belt-like member. As such a substrate, a non-magnetic metal or alloy such as aluminum, stainless steel, brass or the like is formed into a cylindrical shape or a cylindrical shape and subjected to treatment such as polishing or grinding is preferably used.

  In addition, as a base in the case of using a developing method in which the photosensitive drum is brought into direct contact, a cylindrical member having a conductive shaft body and an elastic layer provided around the conductive shaft body is preferably used. As the conductive shaft body, those having conductivity are used, and examples thereof include aluminum, iron, and stainless steel (SUS). As the elastic layer, silicone rubber, an elastomer such as EPDM or urethane, or other resin molding is used.

  In the developing method using magnetic toner, in order to magnetically attract and hold the toner on the developer carrier, a magnet roller in which a magnet is provided is disposed in the developer carrier. In that case, the substrate may be cylindrical and a magnet roller may be disposed inside the substrate.

[Formation of resin layer]
The resin layer can be formed, for example, by dispersing and mixing the components for the resin layer in an organic solvent to form a paint, coating the substrate, drying and solidifying or curing. For dispersing and mixing each component into the coating liquid, a known dispersing apparatus using beads such as a sand mill, a paint shaker, a dyno mill, and a pearl mill can be suitably used. As a coating method, a known method such as a dipping method, a spray method, or a roll coating method can be applied.

  In the present invention, the arithmetic mean roughness Ra (JIS B0601-2001) is preferably 0.4 μm or more and 2.0 μm or less as the roughness of the developer carrying member surface. By setting the Ra on the surface of the developer carrying member within this range, it is possible to properly maintain the amount of toner transported on the developer carrying member, and to stably apply frictional charge to the toner. The thickness of the resin layer is preferably 4 μm or more and 20 μm or less in order to obtain a uniform film thickness, but is not particularly limited to this thickness.

[Development equipment]
Next, a developing device in which the developer carrying member of the present invention is incorporated will be described. FIG. 1 is a schematic cross-sectional view of a developing device according to an embodiment having the developer carrying member of the present invention. As the toner 504, a one-component developer having a magnetic toner is used. In FIG. 1, an electrostatic latent image carrier that holds an electrostatic latent image formed by a known process, for example, an electrophotographic photosensitive drum 501 is rotated in the direction of arrow B. A developing sleeve 508 serving as a developer carrying member carries toner 504 supplied by a hopper 503 serving as a developer container containing developer, and rotates in the direction of arrow A. As a result, the toner 504 is conveyed to the developing region D where the developing sleeve 508 and the photosensitive drum 501 face each other. As shown in FIG. 1, in the developing sleeve 508, a magnet roller 505 in which a magnet is inscribed is disposed in order to magnetically attract and hold the toner 504 on the developing sleeve 508.

  A developing sleeve 508 used in the developing device of the present invention has a resin layer 507 coated on a metal cylindrical tube 506 as a base. In the hopper 503, a stirring blade 510 for stirring the toner 504 is provided. Reference numeral 513 denotes a gap indicating that the developing sleeve 508 and the magnet net roller 505 are not in contact with each other. The toner 504 obtains a triboelectric charge capable of developing the electrostatic latent image on the photosensitive drum 501 by friction between the magnetic toner constituting the developer and the resin layer 507 on the developing sleeve 508. In the example of FIG. 1, in order to regulate the layer thickness of the toner 504 conveyed to the development area D, a magnetic regulation blade 502 made of a ferromagnetic metal is used as the toner layer thickness regulating member. The blade 502 is suspended from the hopper 503 so as to face the developing sleeve 508 with a gap width of about 50 to 500 μm from the surface of the developing sleeve 508. A magnetic force line from the magnetic pole N 1 of the magnet roller 505 concentrates on the magnetic regulation blade 502, so that a thin layer of toner 504 is formed on the developing sleeve 508. A nonmagnetic restricting blade can be used in place of the magnetic restricting blade 502.

  Thus, the thickness of the thin layer of toner 504 formed on the developing sleeve 508 is preferably thinner than the minimum gap between the developing sleeve 508 and the photosensitive drum 501 in the developing region D. . The developer carrying member of the present invention is particularly effective when incorporated in a developing device that develops an electrostatic latent image with a thin layer of toner as described above, that is, a non-contact developing device. In the developing region D, the developer carrier of the present invention is also applied to a developing device in which the thickness of the toner layer is equal to or greater than the minimum gap between the developing sleeve 508 and the photosensitive drum 501, that is, a contact type developing device. be able to. In order to avoid complicated explanation, the following explanation will be made by taking the non-contact developing device as described above as an example.

  In order to cause the toner 504 carried on the developing sleeve 508 to fly, a developing bias voltage is applied to the developing sleeve 508 by a developing bias power source 509 as a bias unit. When a DC voltage is used as the developing bias voltage, the developing sleeve 508 has a voltage value between the potential of the image portion of the electrostatic latent image (the region visualized by the toner 504 attached) and the potential of the background portion. It is preferable to apply to.

  In addition, in the case of so-called regular development, a toner charged with a polarity opposite to that of the electrostatic latent image is visualized by attaching toner to the high potential portion of the electrostatic latent image having a high potential portion and a low potential portion. Is used. In the case of so-called reversal development, a toner that is charged to the same polarity as the polarity of the electrostatic latent image is used for visualization by attaching toner to the low potential portion of the electrostatic latent image having a high potential portion and a low potential portion. To do. Here, the high potential and the low potential are expressions based on absolute values. In any of these cases, the toner 504 is charged by at least friction with the developing sleeve 508.

  FIG. 2 is a schematic cross-sectional view showing another developing device using a one-component developer having magnetic toner as the toner 504. In the developing device of FIG. 2, an elastic regulating blade 511 is used as a toner layer thickness regulating member. The elastic regulating blade 511 is made of a material having rubber elasticity such as urethane rubber or silicone rubber, or a material having metal elasticity such as phosphor bronze or stainless steel. The elastic regulating blade 511 is pressed in the direction opposite to the rotation direction of the developing sleeve 508. In these developing apparatuses, a thin layer of toner is formed on the developing sleeve by elastically pressing the toner layer thickness regulating member to the developing sleeve 508 via the toner layer.

  FIG. 3 is a schematic cross-sectional view showing a developing device when a nonmagnetic one-component developer is used as the toner 504. There is no magnet in the developing sleeve, and a metal cylindrical tube is used as the base. The nonmagnetic toner is frictionally charged by friction with the layer thickness regulating blade 511 or the sleeve coat layer 507, and the surface of the developing sleeve 508 It is carried and conveyed on top. Further, in FIG. 3, a stripping member 512 is provided.

  2 and 3 are the same as those of the developing device shown in FIG. 1, and the same reference numerals denote the same members.

(Developer)
Next, a developer having toner particles used in a developing apparatus incorporating the developer carrying member of the present invention will be described. The toner particles according to the present invention can be produced by a pulverization method or a polymerization method. In the toner using the pulverization method, it becomes easy to encapsulate the magnetic material when the spheroidizing process and the surface smoothing process are performed by various methods. As a result, toner transferability is improved, and toner consumption can be suppressed. Toner particles having a high degree of spheroidization generally have a high charge amount, and depending on the usage situation, the triboelectric charge amount may become too high and charge up may occur. In particular, the developer carrying member used in the present invention can maintain an appropriate triboelectric charge imparting ability with respect to toner particles having such a high degree of spheroidization. Therefore, the developer carrier of the present invention can be more suitably used in combination with a toner having such a high sphericity.

  In addition, since the toner that can be used in the present invention has higher image quality, the toner of the present invention preferably has a mass average particle diameter of 3 μm or more and 10 μm or less in order to faithfully develop finer latent image dots. . It is preferable to add a release agent to the toner. Examples of the release agent include the following. Waxes based on fatty acid esters such as aliphatic hydrocarbon waxes such as paraffin wax, carnauba wax and montan wax. Among them, it is preferable to use a wax having a low melting point from the viewpoint of fixability. Examples of the binder resin for toner include the following. Polystyrene; homopolymer of styrene-substituted product such as poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic Acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer Styrene copolymers such as polymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resins, natural modifications Phenolic resin, heaven Resin-modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin . Further, the toner is externally added with inorganic fine powders such as silica, titanium oxide, and alumina in order to improve environmental stability, triboelectric stability, developability, fluidity, storage stability and cleaning properties, that is, It is preferable to be present in the vicinity of the toner surface. The addition amount of the inorganic fine powder is 0.1% by mass to 5.0% by mass in the toner, preferably 0.5% by mass to 4.0% by mass. In addition, various external additives may be used in combination.

  Hereinafter, the present invention will be specifically described with reference to production examples and examples. First, the measurement method according to the present invention will be described below.

<Analytical method of acrylic resin>
The polymer structure of the acrylic resin was determined by analysis with a pyrolysis GC / MS apparatus “Voyager” (trade name, manufactured by Thermo Electron). Thermal decomposition temperature: 600 ° C., column: HP-1 (15 m × 0.25 mm × 0.25 μm), Inlet: 300 ° C., Split: 20.0, injection amount: 1.2 ml / min, temperature rise: 50 It performed on the conditions of (degreeC (4min) -300 degreeC (20 degreeC / min)).

<Measurement Method of Arithmetic Average Roughness Ra of Developer Carrier Surface>
The arithmetic average roughness Ra of the surface of the developer carrying member was measured using a surface roughness meter: “Surf Coder SE-3500” (trade name, manufactured by Kosaka Laboratory) based on JIS B0601 (2001). The measurement conditions were a cut-off of 0.8 mm, an evaluation length of 4 mm, and a feed rate of 0.5 mm / s, three points in the axial direction (center in the longitudinal direction, 50 mm from each end) × 3 in the circumferential direction. Points (120-degree intervals) = 9 points were measured, and the average value was defined as the arithmetic average roughness Ra of the developer carrier surface of the sample.

<Measurement method of resin layer thickness>
For the measurement of the film thickness of the resin layer, a laser dimension measuring device (manufactured by Keyence Corporation) that measures the outer diameter of the cylinder with laser light was used. Controller: “LS-5500” (trade name) and sensor head: “LS-5040T” (trade name) were used. A sensor unit was separately fixed to an apparatus equipped with a developer carrier fixing jig and a developer carrier feeding mechanism, and the outer diameter of the developer carrier was measured. The measurement was carried out at 30 locations by dividing the developer carrier equally into 30 in the longitudinal direction, and further 30 locations after rotating the developer carrier 90 ° in the circumferential direction, for a total of 60 locations. The average value of the measured values obtained was taken as the outer diameter of the sample. The outer diameter of the substrate was measured before the resin layer was formed, the outer diameter was measured again after the resin layer was formed, and the difference was taken as the film thickness of the resin layer.

<Method for measuring volume resistance value of resin layer>
A 7 μm to 20 μm resin layer is formed on a 100 μm thick PET sheet, and the volume resistivity of the resin layer is measured using a 4-terminal probe with a resistivity meter: “Loresta AP” (trade name, manufactured by Mitsubishi Chemical). Was measured. The measurement environment was a temperature of 20 ° C. to 25 ° C. and a humidity of 50% RH to 60% RH.

<1. Production Example of Acrylic Resin Solution A-1>
The following materials were mixed in a four-neck separable flask equipped with a stirrer, a cooler, a thermometer, a nitrogen inlet tube and a dropping funnel, and stirred until uniform.
Dimethylaminoethyl methacrylate: 36.5 parts by mass
-Lauryl bromide (quaternizing agent): 63.5 parts by mass
-Ethanol: 50 mass parts.

  While continuing to stir, the temperature was raised to 70 ° C. and stirred for 5 hours to quaternize dimethylaminoethyl methacrylate, and quaternary ammonium base-containing monomer (2-methacryloyloxyethyl) lauryldimethylammonium bromide was added. Obtained. After cooling the obtained reaction solution, 21.9 parts by mass of methacrylic acid as a copolymerization component was added to the reaction solution and stirred until uniform. On the other hand, a solution obtained by dissolving 50 parts by mass of ethanol and 1.0 part by mass of azobisisobutyronitrile (AIBN) as a polymerization initiator in 50 parts by mass of ethanol was placed in a dropping funnel. While continuing the stirring, the temperature in the reaction system was raised to 70 ° C., and the polymerization initiator solution in the dropping funnel was added over 1 hour. After completion of the dropwise addition, the mixture was refluxed for 5 hours while introducing nitrogen, and further reacted by adding 0.2 parts by mass of AIBN for 1 hour. Further, this solution was diluted with ethanol to obtain an acrylic resin solution A-1 having a solid content of 40%. Table 1 shows the structure of the obtained acrylic resin.

<2. Production Examples of Acrylic Resin Solutions A-2 to A-16 and a-1 to a-4>
Acrylic resin solutions A-2 to A-16 and a-1 to a-4 are obtained in the same manner as in the production example of the acrylic resin solution A-1, except that the raw materials used are the components shown in Table 1. It was. Regarding the acrylic resin solution A-16, after the solution was formed, ion exchange was performed from bromine ions to p-toluenesulfonic acid ions using an ion exchange resin. In the case of the acrylic resin solution a-1, methacrylic acid was not used. Table 1 shows the structures of the obtained acrylic resins A-2 to A-16 and a-1 to a-4.

<3. Production Example of Acrylic Resin Particle A-17>
The polymerization reaction was carried out under the same conditions as in the production example of the acrylic resin solution A-1. After completion of the reaction, acrylic resin particles A-17 having a mass average particle diameter (D4) of 4.0 μm were obtained through drying and pulverization processes.

<4. Resins other than acrylic resin>
The following resins were used.
B-1: Resol type phenol resin: “J-325” (trade name, manufactured by Dainippon Ink & Chemicals, solid content: 60%),
B-2: Butylated melamine resin: “L-109-65” (trade name, manufactured by Dainippon Ink and Chemicals, 60% solid content).

<5. Example of toner production>
-Styrene: 76 parts by mass
N-butyl acrylate: 24 parts by mass,
・ Divinylbenzene: 0.5 parts by mass
Saturated polyester resin (Mn = 11000, Mw / Mn = 2.6, acid value = 12 mgKOH / g, Tg = 72 ° C.): 7 parts by mass
-Aluminum salicylate compound ("Bontron E-88", trade name, manufactured by Orient Chemical Co., Ltd.): 0.5 parts by mass
Magnetic iron oxide (average particle size 0.2 μm, coercive force 11.2 KA / m, remanent magnetization 8.8 Am ² / kg, saturation magnetization 80.3 Am ² / kg): 90 parts by mass.

  This mixture was kneaded by a twin-screw kneading extruder heated to a temperature of 130 ° C. After cooling the obtained kneaded product, the coarsely pulverized product obtained by coarse pulverization with a hammer mill was finely pulverized using a mechanical pulverizer: “Turbo Mill T250” (trade name, manufactured by Turbo Kogyo Co., Ltd.). Thereafter, a thermal spheronization treatment was performed. The finely pulverized powder that has been subjected to thermal spheronization treatment is classified and removed at the same time by ultra-fine and coarse powders using the "Elbow Jet Classifier" (trade name, manufactured by Nittetsu Mining Co., Ltd.) Thus, toner particles having a mass average particle diameter (D4) of 6.3 μm and a circularity of 0.966 were obtained. By adding 1.0 part by mass of hydrophobic colloidal silica to 100 parts by mass of the toner particles, and mixing and dispersing with a Henschel mixer: “FM-75” (trade name, manufactured by Mitsui Miike Chemical Co., Ltd.), one magnetic component Toner 1 was obtained.

[Example 1]
<Preparation of paint intermediate>
The following materials were mixed, and dispersed for 1 hour in a sand mill: “Star Mill” (trade name, manufactured by Ashizawa Finetech Co., Ltd.) using glass beads having a diameter of 0.8 mm as media particles to obtain a coating intermediate.
Acrylic resin solution A-1: 100 parts by mass as a solid content,
Conductive particles: “TGP-7” (trade name, manufactured by Tokai Carbon Co., Ltd.): 50 parts by mass
-Ethanol: 150 mass parts.

<Production of paint for resin layer>
Next, 5 parts by mass of unevenness imparting particles: “Nika Beads ICB-0520” (trade name, manufactured by Nippon Carbon Co., Ltd.) is added to the coating intermediate, and a sand mill using glass beads having a diameter of 1.5 mm as media particles for 40 minutes. The resin layer coating material was obtained by dispersing. The volume resistance value of the resin layer coating material was 0.4 Ω · cm.

<Formation of resin layer>
Next, the solid content concentration was adjusted to 30% by adding ethanol to the resin layer coating material. An aluminum cylindrical tube with an outer diameter of 10.0 mm and a length of 255 mm is placed on a turntable and rotated. Masking is applied to both ends (driving side: 25 mm, non-driving side: 9 mm), and the air spray gun is set at a constant speed of 40 mm / sec. The resin layer coating was applied to the surface of the cylindrical tube while being lowered at, thereby forming a resin layer. The coating conditions were used in an environment of a temperature of 30 ° C./humidity of 35% RH, and the resin layer coating material was used while being controlled at a temperature of 28 ° C. in a thermostatic bath. Subsequently, the resin layer was cured by heating at a temperature of 150 ° C. for 30 minutes in a hot air drying furnace, to produce a developer carrier D-1 having Ra = 0.96 μm and a resin layer thickness of 10 μm. Table 2 lists the formulation of the resin layer of the developer carrier (developing sleeve) D-1.

<Image evaluation>
A magnet roller was inserted into the developer carrier D-1, and then incorporated into a cartridge of a laser beam printer LaserJet 1505n (trade name; manufactured by Hewlett-Packard). Using the toner, the triboelectric charge amount of the toner in an environment of 30 ° C./80% humidity (H / H), and the triboelectric charge amount of the toner in an environment of 15 ° C./humidity 10% RH (L / L). And evaluated the ghost. As shown in Table 2, the triboelectric charge amount of the toner at H / H was high, the triboelectric charge amount of the toner at L / L was slightly increased with respect to H / H, and the ghost was also good. . That is, by using the developer carrying member of the present invention, it was possible to quickly impart high triboelectric charge to the toner and to suppress toner charge-up.
The toner charge amount at H / H and L / L and the ghost at L / L were evaluated as follows.

(1) Toner triboelectric charge amount in H / H (μC / g)
The cartridge was left in an H / H environment for one day. After standing, the cartridge was loaded into LaserJet 1505n, and one solid black image was output. The toner adhering to the surface of the developer carrying member immediately after image output was collected in a Faraday cage, and the charge amount was measured with an electrometer: “KEITHLEY 616” (trade name, manufactured by Toyo Technica). Further, the triboelectric charge amount of the toner per mass was obtained from the collected mass.

(2) Charge amount of toner at L / L (μC / g)
The cartridge was left in an L / L environment for one day. Then, the cartridge was loaded into LaserJet 1505n, one solid black image was output, and the charge amount of the toner adhering to the surface of the developer carrying member immediately after image output was measured. Subsequently, after outputting 50 solid white images in the continuous mode, the charge amount of the toner adhering to the surface of the developer carrying member was measured. The charge amount was measured in the same manner as in the case of H / H.

(3) Ghost evaluation at L / L The above cartridge was left in an L / L environment for one day. After standing, the cartridge was loaded into LaserJet 1505n, and ghost was evaluated. As the output image, use a solid black hieroglyph image (square, round, etc.) at equal intervals on a white background that corresponds to the circumference of the developer carrier at the tip, and halftone in the other parts. It was. Then, ranking was performed according to how the ghost of the hieroglyph image appeared on the halftone.
A: No difference in shading is observed.
B: A slight shade difference can be confirmed depending on the viewing angle.
C: A ghost is clearly confirmed visually.
D: A ghost appears clearly as light and shade, and a light and shade difference of two or more rounds of the developer carrying member is confirmed.

  The ghost is caused by a difference in developing ability (difference in frictional charge) between the toner that is not consumed in the developing process and remains on the developer carrying member and the toner that is newly supplied on the developer carrying member. It is a phenomenon that occurs. If a high triboelectric charge can be quickly applied to the toner and the toner charge-up can be suppressed, the difference in the triboelectric charge amount can be reduced and the ghost can be improved.

[Example 2 to Example 19, Comparative Example 1 to Comparative Example 6]
Developer carriers D-2 to D-19 and d-1 to d-6 were prepared and evaluated in the same manner as in Example 1 with the formulations listed in Table 2. In Examples 15 to 17 and Comparative Example 1, a resin (B-1 or B-2) other than an acrylic resin was also added during the production of the coating material intermediate. The solid content concentration of the coating material for the resin layer was adjusted as appropriate. Table 2 shows the physical properties of the developer carrier and various evaluation results.

  As can be seen from the above results, by using the developer bearing member of the present invention, it was possible to quickly impart high frictional charge to the toner and to suppress the toner charge-up.

  When Example 2 to Example 9 are compared, it can be seen that as the carbon number of the long-chain alkyl group of the unit (2) increases, the charge amount of the toner at H / H increases. That is, it was found that as the carbon number of the long-chain alkyl group of the unit (2) increases, the toner can be quickly imparted with high frictional charge. On the other hand, when the number of carbon atoms of the long-chain alkyl group of the unit (2) was increased too much as in Comparative Example 5, the toner was charged up in an L / L environment, and the ghost deteriorated. This is because by increasing the number of carbon atoms of the long-chain alkyl group in the unit (2), the acrylic resin itself tends to crystallize, and the conductive particles in the resin layer no longer exist uniformly. I guess. In Comparative Example 4, the triboelectric charge amount of the toner at H / H was low because the carbon number of the long chain alkyl group of the unit (2) was small. That is, in Comparative Example 4, rapid frictional charging could not be imparted to the toner.

  When Example 1 is compared with Examples 10 to 14, the higher the ratio of the unit (1), the more effective the toner charge-up suppression, and the higher the ratio of the unit (2), the faster the frictional charging with respect to the toner. It turns out that it can be granted.

  In Example 14, a unit (1) having an acrylic acid structure was used, but high frictional charge could be quickly applied to the toner and toner charge-up could be suppressed.

  In Example 15 and Example 16, an acrylic resin and a resin other than an acrylic resin were used for the resin layer of the developer carrying member, but both can quickly impart high triboelectric charge to the toner and charge up the toner. Could be suppressed.

  In Examples 17 and 18, the anion species of the acrylic resin was changed, but as in the case of using bromine, high triboelectric charge could be quickly applied to the toner, and toner charge-up could be suppressed.

  In Example 19, the acrylic resin particles were added instead of the acrylic resin solution. However, as in the case where the acrylic resin solution was added, high triboelectric charge could be quickly applied to the toner, and toner charge-up could be suppressed. .

  In Comparative Example 1, since the acrylic resin of the present invention was not used, the charge amount of the toner was low at H / H, the charge amount of the toner at L / L was significantly increased with respect to H / H, and ghosting occurred. It got worse. This is due to the fact that rapid triboelectric charge could not be applied to the toner, the resin layer did not have ionic conductivity, and the toner was charged up.

  In Comparative Example 2 and Comparative Example 3, the component of unit (1) was not used. Therefore, the toner charge-up could not be suppressed, and the charge amount of the toner at L / L was greatly increased with respect to H / H, and the ghost was deteriorated.

  In Comparative Example 6, since no conductive particles were used, high frictional charge could not be quickly applied to the toner, and toner charge-up could not be suppressed.

501... Image carrier (photosensitive drum)
502... Toner layer thickness regulating member (magnetic regulating blade)
503... Hopper 504... Toner 505... Magnet roller 506.
507... Resin layer 508... Developer carrier (developing sleeve)
509... Power supply 510... Stirring blade 511... Toner layer thickness regulating member (elastic regulating blade)
512... Stripping member 513... Gap between developing sleeve and magnet roller

Claims (1)

In a developer carrier having a substrate and a resin layer formed on the surface of the substrate, the resin layer contains an acrylic resin and conductive particles,
The acrylic resin has a unit represented by the following formula (1) and a unit represented by the following formula (2):

[In the formula (1), R ₁ represents a hydrogen atom or a methyl group. ],

[In Formula (2), R ₂ represents a hydrogen atom or a methyl group, and R ₃ represents an alkylene group having 1 to 4 carbon atoms. At least one of R ₄ , R ₅ and R ₆ represents an alkyl group having 6 to 18 carbon atoms, and the remaining group represents an alkyl group having 1 to 5 carbon atoms. A ⁻ represents an anion. ].

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