JP2005208630A - Electrophotographic developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic developer which can maintain high picture quality while sufficiently keeping cleaning property even when an electrophotographic developer ring a spherical toner is used. <P>SOLUTION: The electrophotographic developer contains a spherical toner manufactured by a polymerization method and a toner with spherical form as the basic form manufactured by a polymerization method and having pores on its surface, or a toner manufactured by a pulverization method. The spherical toner manufactured by a polymerization method, and the toner are surface treated with respective external additives. The amount of the external additive used for the surface treatment of the toner having a spherical form as the basic form manufactured by a polymerization method and having pores on its surfaces or the toner manufactured by a pulverization method is larger than the amount of the external additive used for the surface treatment of the spherical toner manufactured by a polymerization method. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic developer, and more particularly to an electrophotographic developer capable of obtaining a higher quality image while ensuring cleaning properties.

  In recent years, toner having a high sphericity produced by a polymerization method has been used.

  Such toner with high sphericity has the merit of improving the quality of the obtained image. On the other hand, the toner remaining on the surface of the latent image carrier after transfer is spherical toner. There is a demerit that it is difficult to clean with a cleaning device.

  On the other hand, a method has been proposed in which the polymerized toner is modified to improve the cleaning property (for example, Patent Document 1). In addition, a method has been proposed in which non-spherical toner is mixed with spherical toner at a certain ratio to improve cleaning properties (for example, Patent Document 2).

  However, in the study by the present inventors, when a toner having a high sphericity manufactured by a polymerization method and a non-spherical toner such as a toner obtained by deforming the polymer toner are used in a mixed manner in order to improve cleaning properties, Non-spherical toners such as modified toners, for example, have stronger adhesion to spherical toners, such as carriers in two-component developers and developing sleeves in one-component developers. The phenomenon that the spherical toner is selectively developed and the non-spherical toner tends to remain in the developing device, and the charge of the developer is lowered and the image quality is deteriorated due to the increase in the proportion of the non-spherical toner in the developing device. There has occurred.

  That is, since the developability of toner differs depending on the shape of the surface thereof, it is a problem that toner having a nearly spherical surface shape is selectively developed in a long-term printing process. .

  On the other hand, amorphous silicon photoconductors have a high surface hardness and a long life, but the surface is difficult to polish, so if water-soluble ion products are attached by a charger or the like, image flow occurs due to moisture absorption in a high humidity environment. The problem of doing is known.

  Therefore, it is a common practice to remove the moisture on the surface of the amorphous silicon photosensitive layer by attaching an abrasive, which is inorganic fine particles such as titanium oxide, to the toner surface.

However, according to the study by the present inventors, when spherical toner is used to improve the image quality, the adhesive force of the abrasive to the toner surface becomes weak, and the abrasive tends to be detached from the toner surface, resulting in a decrease in polishing ability. As a result, it has been found that an image flow may occur.
JP-A-7-114212 JP 7-49584 A

  The present invention has been made in view of the above problems, and even when an electrophotographic developer containing a spherical toner produced by a polymerization method is used, high image quality is maintained while sufficiently ensuring cleaning properties. An object of the present invention is to provide an electrophotographic developer that can be used.

  Furthermore, in the present invention, even when an electrophotographic developer containing a spherical toner produced by a polymerization method is used, the effect of preventing the occurrence of image flow due to the addition of a small amount of abrasive is maximized. An object of the present invention is to provide an electrophotographic developer that can be used.

The electrophotographic developer of the present invention includes a spherical toner produced by a polymerization method, a toner produced by a polymerization method and having a spherical shape as a basic shape and having pores on its surface, or a toner produced by a pulverization method. The spherical toner produced by the polymerization method, the toner produced by the polymerization method and having a spherical shape as a basic shape, and the toner produced by the pulverization method are each surface-treated with an external additive, Surface treatment of spherical toner produced by the above-mentioned polymerization method, wherein the amount of external additive used for the surface treatment of the toner produced by the polymerization method and having a spherical shape as a basic shape and having pores on the surface or the toner produced by the pulverization method It is characterized by being larger than the amount of the external additive used in the above.
Further, it is preferable that an abrasive is included as the external additive only in a toner produced by a polymerization method and having a spherical shape as a basic shape and having pores on its surface or a toner produced by a pulverization method.

  In the electrophotographic developer, the volume average particle diameter of the spherical toner is preferably larger than the volume average particle diameter of the non-spherical toner.

According to the electrophotographic developer of the present invention, a toner manufactured by a polymerization method and having a spherical shape as a basic shape or having a pore on the surface thereof, or a toner manufactured by a pulverization method, that is, a deformed toner having irregularities on the surface is a spherical toner. By using the toner in combination with the toner, it is possible to maintain the high image quality of the spherical toner while sufficiently securing the cleaning property due to the irregularities on the surface of the irregular shaped toner. In addition, there is usually a phenomenon of selective development in which toner that is difficult to develop and toner that is difficult to develop are generated, and toner that is difficult to develop continues to accumulate in the developing device. When the amount is larger than the amount of the external additive of the spherical toner, for example, when used as a two-component developer, the adhesion between the irregular-shaped toner and the carrier can be reduced, or the one-component developer. Can be used, the adhesive force to the developing sleeve can be reduced, and the selective development of spherical toner can be suppressed.
In addition, by including the abrasive only in the irregularly shaped toner that tends to remain on the surface of the electrostatic carrier, the polishing effect on the surface of the electrostatic carrier can be obtained with a small amount of abrasive.

  Further, when the volume average particle size of the spherical toner is larger than the volume average particle size of the deformed toner, the developability and transferability of the spherical toner are improved, so that the deformed toner remains on the surface of the electrostatic carrier, It is scraped off by a cleaning blade or the like, and the cleaning performance by the irregular shaped toner can be further enhanced.

  The developer for electrophotography of the present invention includes a spherical toner produced by a polymerization method, and a toner produced by a polymerization method and having a spherical shape as a basic shape and having pores on the surface thereof, or a toner produced by a pulverization method. Hereinafter, the spherical toner manufactured by the polymerization method is simply referred to as “spherical toner”, and the toner manufactured by the polymerization method having a spherical shape as a basic shape and having pores on the surface or the toner manufactured by the pulverization method are collectively referred to as “ It may be referred to as a “typical toner”.

The spherical toner in the present invention means a toner having a shape factor SF-2 indicating the degree of unevenness on the surface of the toner, preferably 120 or less, more preferably 115 or less. Here, the shape factor SF-2 can be expressed by the formula shape factor SF-2 = (peripheral length of toner particles) ² / (projected area of toner particles) × (1 / 4π) × 100. The projected particle image is obtained by taking a photograph with a magnification of 1000 to 10000 using a known method and an electron microscope, and randomly sampling the toner image. The image information can be obtained by introducing the image information into an image analysis apparatus and analyzing it.

  Also, when the irregular shaped toner is produced by a polymerization method and has a spherical shape as a basic shape and has irregularities on its surface, its shape factor SF-2 is preferably 135 or less, more preferably 130 or less. The shape factor SF-2 is preferably 150 to 180.

  The spherical toner and the irregular toner in the present invention are different only in shape, and both of them may be composed of a material that is usually used as a developer for electrophotography. Further, the present invention can be applied to any type of toner constituting the developer. For example, a one-component developer may be used, or a two-component developer may be mixed with a carrier. The one-component developer only needs to have at least a binder resin and a colorant. For example, a colorant is dispersed and mixed in the binder resin, and additives such as a charge control agent and a surface treatment agent are added as necessary. Externally added or internally added. Further, as a two-component developer, it may be mixed with a carrier. Note that the spherical toner and the irregular toner may have different compositions, that is, the types and amounts of the binder resin and the colorant constituting the toner, but are preferably the same.

Examples of the binder resin used in the toner of the present invention include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, and styrene. -Vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer (styrene-acrylic acid copolymer, styrene-methyl acrylate copolymer, styrene -Ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer), styrene-methacrylic acid copolymer (styrene-methacrylic acid copolymer) Polymer, styrene-methyl methacrylate copolymer, styrene-methacrylic acid Ethyl acrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate copolymer, styrene-phenyl methacrylate copolymer), styrene-α-methyl chloroacrylate copolymer, styrene-acrylonitrile- Styrenic resins such as acrylate copolymers (homopolymers or copolymers containing styrene or styrene-substituted products), polyvinyl chloride, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-ethyl acrylate copolymer, polyvinyl Butylene, ethylene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, xylene resin, polyamide resin, etc. Alone It is used in combination of two or more.

The styrene-acrylic polymer is a copolymer of a styrene monomer and an acrylic monomer, and other monomers may be copolymerized as necessary. As a styrene-type monomer, following formula (1):
CH2 = C (R1) −Φ (1)
In the formula, R1 is a hydrogen atom, a lower alkyl group having 4 or less carbon atoms or a halogen atom, Φ is a benzene ring, and this benzene ring is substituted with a lower alkyl group having 4 or less carbon atoms, a halogen atom, or the like. Mention may be made of a monomer represented by, for example, styrene, vinyltoluene, α-methylstyrene, α-chlorostyrene, o-, m-, p-chlorostyrene, vinylxylene, etc. These styrenic monomers may be used alone or in combination of two or more.

On the other hand, as the acrylic monomer, the following formula (2):
CH2 = C (R2) -COO-R3 (2)
In the formula, R2 is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms, and R3 is a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 18 or less carbon atoms. Bodies such as acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate , Β-hydroxyethyl acrylate, γ-hydroxyacrylate propyl, δ-hydroxyacrylate butyl, β-hydroxyethyl methacrylate and the like. In addition to those exemplified above, other ethylenically unsaturated carboxylic acids or anhydrides thereof, such as maleic acid, fumaric acid, crotonic acid, itaconic acid and acid anhydrides thereof can be mentioned. These acrylic monomers may be used alone or in combination of two or more.

Examples of the monomer other than the styrene monomer and acrylic monomer include the following.
Following formula (3):
CH2 = CH-O-R4 (3)
In the formula, R4 is a monovalent hydrocarbon group having 12 or less carbon atoms, such as vinyl methyl ether, vinyl ethyl ether, vinyl n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether, and the like.
Following formula (4):
CH2 = C (R5) -C (R6) = C-R7 (4)
In the formula, each of R5 to R7 is a hydrogen atom, a lower alkyl group having 4 or less carbon atoms, or a halogen atom, such as butadiene, isoprene, chloroprene, or the like.
Following formula (5):
CH2 = C (R8) (R9) (5)
In the formula, R8 and R9 are each a monoolefin represented by a hydrogen atom or an alkyl group having 8 or less carbon atoms, such as ethylene, propylene, isobutylene, butene-1, pentene-1, 4-methyl-pentene-1. etc.
Following formula (6):
CH2 = CH-OOCR10 (6)
In the formula, R10 is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms, such as vinyl formate, vinyl acetate, and vinyl propionate. In addition to the above, in order to reinforce the charge control action of the fixing resin itself, an anionic group such as a carboxyl group, a sulfone group or a phosphone group, a primary, secondary or tertiary amino group, Random copolymerization and block copolymerization of monomers containing cationic groups such as basic nitrogen-containing groups such as quaternary ammonium groups, amide groups, imino groups, imide groups, hydrazino groups, guanidino groups, and amidino groups It can also be incorporated into the fixing resin by graft copolymerization or the like.

The above-mentioned styrene-acrylic polymer has the fixing property and electric chargeability required for the toner. In general, the styrene-based monomer (A) and the acrylic monomer (B) are converted into A : B = 50: 50 to 90:10 are preferably contained in a weight ratio, and the content of the monomer other than the styrene monomer and the acrylic monomer is 20.0% by weight. The acid value of the polymer is preferably 25 or less, and the glass transition temperature (Tg) is preferably in the range of 50 to 75 ° C.

  As the polyester resin, those obtained by polycondensation of a known polyhydric alcohol and polyvalent carboxylic acid can be used.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1 Diols such as 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, hydrogenated bisphenol A, polyoxyethylene Bisphenols such as bisphenol A and polyoxypropylene bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol , Dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methylpropanetriol, 2-methyl-1, Examples of trihydric or higher alcohols such as 2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene can be given, and these polyhydric alcohols are used alone. However, a combination of two or more types can be used.

  Polycarboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-butyl succinate Acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid Acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetrical Acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, Trivalent or higher carboxylic acids such as pyromellitic acid and empole trimer can be raised. These polyvalent carboxylic acids can be used singly or in combination of two or more, and can also be used in the form of an acid anhydride or a partially esterified product.

Further, the acid value of the fixing resin composed of the above-described polyester resin is preferably 10 or less, and the glass transition temperature (Tg) is preferably in the range of 50 to 75 ° C. That is, if the acid value is higher than the above range, the positive charging characteristics of the toner of the present invention may be impaired, and if the Tg is less than 50 ° C., the toner is likely to be fused with each other, so that the toner can be stored. When the Tg is higher than 75 ° C., the toner fixing property tends to be poor.

  The binder resin is preferably composed only of the above-described polyester resin, but other heat can be used as long as various characteristics such as positive charging characteristics (particularly charging stability), fixing properties, and offset resistance of the toner are not impaired. A thermosetting resin such as a plastic resin (for example, styrene resin, styrene-acrylic resin) or an epoxy resin may be contained in a small amount of 10% by weight or less.

  The release agent (wax) used in the toner of the present invention includes, for example, fatty acid polyhydric alcohol ester or higher alcohol ester; aliphatic carbonization such as paraffin wax, petroleum wax, polyethylene wax, polypropylene wax, and oxidized polyethylene wax. Hydrogen wax; polypropylene, polyethylene, propylene-ethylene copolymer having a number average molecular weight in the range of 1,000 to 10,000, particularly 2,000 to 6,000; alkylene bis fatty acid amide compound; Fischer-Tropsch wax, etc. Synthetic waxes; natural waxes such as montan wax and carnauba wax. The release agent is preferably used in an amount of 1 to 10 parts by weight, particularly 2 to 6 parts by weight, based on 100 parts by weight of the binder resin.

  As the colorant used in the toner of the present invention, the following are generally used, and it is appropriate to use 2 to 20 parts by weight per 100 parts by weight of the binder resin.

  Colorant for black toner: carbon black, acetylene black, lamp black, aniline black, etc.

  Colorant for yellow toner: C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 5, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 4, C.I. I. Pigment yellow 81, C.I. I. Pigment yellow 97, C.I. I. Azo pigments such as CI Pigment Yellow 93; inorganic pigments such as yellow iron oxide and ocher; I. Nitro dyes such as Acid Yellow 1; C.I. I. Solvent Yellow 2, C.I. I. Solvent Yellow 6, C.I. I. Solvent Yellow 14, C.I. I. Solvent Yellow 15, C.I. I. Solvent Yellow 19, C.I. I. Oil-soluble dyes such as Solvent Yellow 21

  A preferable one is C.I. I. Benzidine pigments such as CI Pigment Yellow 12.

  Colorant for magenta toner: C.I. I. Pigment red 49, C.I. I. Pigment red 57, C.I. I. Pigment red 81, C.I. I. Pigment red 122, C.I. I. Pigment red 184, C.I. I. Pigment red 238, C.I. I. Solvent Red 19, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Basic Red 10, C.I. I. Disperse Red 15 etc.

  A preferable one is C.I. I. It is a quinacridone pigment such as CI Pigment Red 122.

  C. Colorant for cyan toner: C.I. I. Pigment blue 15, C.I. I. Pigment blue 16, C.I. I. Solvent Blue 55, C.I. I. Solvent Blue 70, C.I. I. Direct Blue 25, C.I. I. Direct Blue 86 etc.

A preferable one is C.I. I. It is a copper phthalocyanine pigment such as CI Pigment Blue 15.
As the charge control agent used in the toner of the present invention, conventionally known charge control agents can be used. Oil-soluble dyes such as nigrosine base (CI50415), oil black (CI26150), spiron black, metal complex dyes, Charge control agents such as quaternary ammonium salts, polyimidazole salts, naphthenic acid metal salts, fatty acid metal soaps, resin acid soaps, acrylic acid or methacrylic acid ester resins are used as necessary. The charge control agent is preferably used in an amount of 2 to 20 parts by weight, particularly 5 to 15 parts by weight, based on 100 parts by weight of the binder resin.

The electrophotographic developer of the present invention contains an external additive in addition to spherical and irregular shaped toners. That is, the spherical toner and the irregular toner are surface-treated with the external additive.
Examples of the external additive include a surface treatment agent and an abrasive. In general, the spherical toner and the non-spherical toner may both be surface-treated with completely different external additives, may be partially surface-treated with different external additives, or may be the same external additive. It may be surface-treated.

Examples of the surface treatment agent include inorganic fine powders such as silica, alumina, zinc oxide, magnesium oxide, and calcium carbonate; organic fine powders such as polymethyl methacrylate; fatty acid metal salts such as zinc stearate; The above can be used in combination.

  As an abrasive | polishing agent, all the things normally used in the said field | area can be used, for example. Specifically, metal oxides such as titanium oxide, strontium titanate, silica, zirconium oxide, aluminum oxide, zinc oxide, zinc stearate or the like, colloidal silica, hydrophobic silica, silane coupling agent or titanium coupling. And the like surface-treated with an agent. Of these, titanium oxide and strontium titanate are preferable. The titanium oxide may be in any shape such as granular or needle-like, and the crystal form may be any of anatase type, rutile type or amorphous. This makes it easy to adjust the resistance of the toner, and because titanium oxide itself is a white conductive material, it can be applied to color toners without harming the hue.

  When using a latent image carrier having an amorphous silicon photosensitive layer as described later, a charged product adhering to the surface of the photosensitive layer, a component in the toner, or a component such as talc contained in the transfer paper is used. In order to remove the toner, it is necessary to surface-treat the toner with the above-described abrasive.

  In the present invention, the spherical toner which is easy to be transferred from the latent image carrier due to its shape and does not easily reach the cleaning device of the latent image carrier where the abrasive exhibits an effect does not contain the abrasive. The amount of the abrasive used is suppressed by surface-treating the abrasive only to the irregularly shaped toner that is likely to reach.

  The external additive other than the abrasive is attached to the toner so that the amount of the external additive of the deformed toner is larger than the amount of the external additive of the spherical toner. For example, it is about 0.01 to 2.0 parts by weight, preferably about 0.1 to 1.0 parts by weight for 100 parts by weight of spherical toner, and 0.1 to 2 parts for 100 parts by weight of irregularly shaped toner. About 0 parts by weight, preferably about 0.2 to 1.5 parts by weight is appropriate. The amount of the external additive of the irregular toner is preferably about 1.2 to 3 times, more preferably about 1.5 to 2 times the amount of the external additive of the spherical toner. When smaller than the above range, spherical toner tends to be preferentially developed and tends to cause poor cleaning. When larger than the above range, the developed amount of irregular toner tends to be too large and image quality tends to deteriorate. There is. As described above, when the amount of the external additive is larger than that of the spherical toner, the amount of the external additive can be reduced when the toner is used as a two-component developer. Alternatively, when used as a one-component developer, the adhesion to the developing sleeve can be reduced, and the selective development of irregularly shaped toner can be suppressed.

The abrasive is preferably used in an amount of about 0.1 to 2.1 parts by weight, preferably about 0.3 to 1.3 parts by weight, based on 100 parts by weight of the irregularly shaped toner. As a surface treatment method using an additive, a method known in the art can be used. Examples thereof include a method of mixing spherical toner, irregularly shaped toner and abrasive using a Henschel mixer, a V-type mixer, a turbula mixer, a hybridizer, and the like. At this time, it is preferable to appropriately adjust the mixing time and the stirring speed.

  Further, the method of increasing the amount of external additive of the irregular toner to be larger than the amount of external additive of the spherical toner is a method in which the spherical toner and the irregular toner are separately surface-treated with different external additive amounts and mixed; A method of surface-treating a deformed toner with a predetermined amount of an external additive, introducing a spherical toner that has not been surface-treated into the toner and a predetermined amount of an external additive, and treating both of them together; combining these The method etc. are mentioned.

  The spherical toner in the present invention is a melt granulation method, spray granulation method, wet granulation method (for example, suspension method, suspension polymerization method, emulsion polymerization method, dispersion polymerization method, interfacial polymerization method, seed polymerization method, etc.) And a phase inversion emulsification method (for example, see JP-A-4-303849 and JP-A-5-66600). Of these, wet granulation is preferable, and suspension polymerization and emulsion polymerization are more preferable in consideration of manufacturing equipment, productivity, and ease of realizing the circularity described above.

  Specifically, as a suspension polymerization method, a monomer solution in which a colorant and optionally an additive are dispersed is suspended in a dispersed particle size in a solvent incompatible with this solution, and the monomer is polymerized in a suspended state. Examples thereof include a method for obtaining a spherical toner and a method for polymerizing monomers in micelles as emulsion polymerization. The volume average particle diameter and shape factor SF-1 of the spherical toner are the heat treatment temperature or timing in the production process, the magnitude of the applied force (mechanical impact force, rotation speed of stirring, rotation speed, etc.) or the timing thereof, It can be adjusted by appropriately selecting and combining various production conditions such as the type of raw material. In addition, the shape factor SF-2 can be adjusted by changing the powder particle diameter or addition amount of tricalcium phosphate added during polymerization.

  According to the internal pulverization method of the irregular shaped toner in the present invention, as a pulverization method, first, a binder resin, a colorant and optionally an additive are premixed with a Henschel mixer, a V-type mixer or the like, and then a twin screw extruder or the like. And kneading using a kneader, and then cooling the kneaded product, followed by pulverizing with a jet mill or a turbo mill.

  A toner manufactured by a polymerization method and having a spherical shape as a basic shape and having pores on the surface thereof corresponds to this by removing the inorganic fine particles after forming a spherical toner by polymerizing with a monomer phase to which inorganic fine particles are added. Examples thereof include a method for obtaining a non-spherical toner that forms concave portions on the surface (see JP-A-7-114212). As a result, the shape of the irregularly shaped toner can be moderately smoothed, the image quality can be improved, and the effect of fixing the external additive used for the surface treatment of the toner can also be obtained.

  In the method using inorganic fine particles, the size of the inorganic fine particles can be appropriately adjusted in consideration of the particle size of an external additive described later. For example, the particle diameter is about 1 to 35% of the particle diameter of the toner to be obtained, or the particle diameter range of the external additive described later. Moreover, it is preferable that the addition amount of the inorganic fine particle to a monomer phase is 1-100 weight part with respect to 100 weight part of monomers. In these methods, as described above, heat, force, raw materials, etc. in the production process, particularly in the polymerization method, the volume average particle size of the irregular shaped toner can be adjusted by appropriately adjusting and combining the particle size, addition amount, etc. of the inorganic fine particles. The diameter and shape factor SF-2 can be adjusted.

  In the electrophotographic developer according to the present invention, it is preferable that the volume average particle diameter of the spherical toner is larger than the volume average particle diameter of the deformed toner in consideration of improvement in image quality, cleaning properties, and the like. In addition, the difference between the spherical toner and the volume average particle diameter of the irregular toner is not too large. For example, the difference is preferably within about 2 μm, and from another viewpoint, it is preferably within about 25%. Thereby, the developability and transferability of the spherical toner are improved, so that the cleaning property can be further improved and the image quality can be improved.

  The volume average particle diameter of the spherical toner is, for example, about 4 to 9 μm in consideration of manufacturing difficulty, cleaning properties when used in an image forming apparatus, improvement in image quality, and the like. Here, the volume average particle diameter can be measured with an apparatus capable of capturing a particle image of toner particles, specifically, a Coulter counter (TA-2) manufactured by Coulter.

  In addition, the electrophotographic developer in the present invention preferably contains more spherical toner than irregularly shaped toner. The term “contained in a large amount” means that depending on the toner raw material used, the weight may be large or the volume may be large, but a large number is preferable. In any case, it is appropriate that the spherical toner is 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, 98% or more with respect to the total toner. Thus, when the content of the spherical toner is large, the image quality can be improved due to the spherical shape of the toner.

  When the toner of the present invention is used as a two-component developer, the carrier is not particularly limited, and various types are used.

The core particle of the carrier is generally made of a known magnetic material such as sintered ferrite, magnetite, lithium, manganese, or iron powder. As the magnetic powder used for the production of the core particles, any magnetic powder known per se can be used. For example, iron trioxide (Fe ₃ O ₄ ), iron sesquioxide (γ-Fe _2). O ₃₎ and iron oxide ferromagnetic such as iron oxide, zinc (ZnFe ₂ O _4), iron oxide, yttrium _{(Y 3 Fe 5 O 12)} , cadmium oxide (CdFe ₂ O _4), iron oxide gadolinium (Gd3Fe ₅ O ₁₂ ), copper iron oxide (CuFe ₂ O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), iron neodymium (NdFeO ₃ ), iron barium oxide (BaFe ₁₂ O ₁₉ ), manganese iron oxide (MnFe ₂ O ₄₎ ), Iron oxide lanthanum (LaFeO ₃ ), or ferrites such as these composites, or ferromagnetic metals or alloys such as iron powder (Fe), cobalt powder (Co), nickel powder (Ni), etc. alone or in combination The It is possible to have. For example, manganese-magnesium ferrite, nickel-zinc ferrite, copper-zinc ferrite, lithium ferrite and the like can be mentioned.

  The particle shape of the magnetic material is not particularly limited, and may be any shape such as a spherical shape, a cubic shape, or an indefinite shape.

  Examples of the resin used for the coating layer for covering the core particles to protect the core particles include (meth) acrylic resins, styrene resins, styrene- (meth) acrylic resins, olefin resins (polyethylene, chlorinated polyethylene). , Polypropylene, etc.), polyester resins (polyethylene terephthalate, polycarbonate, etc.), unsaturated polyester resins, vinyl chloride resins, polyamide resins, polyurethane resins, epoxy resins, silicone resins, fluorine resins (polytetrafluoro) Ethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, etc.), phenol resins, xylene resins, diallyl phthalate resins and the like. The said resin may be used individually by 1 type, and may use 2 or more types together.

  The coating layer may contain a small amount of additives for adjusting the properties of the coating layer, such as silica, alumina, carbon black, and fatty acid metal salt, as necessary.

  As a method for forming the coating layer on the surface of the core particles, for example, a mechanical mixing method, a spray method, a dipping method, a fluidized bed method, a rolling bed method, or the like can be employed.

  Examples of the solvent used to form the coating layer include aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as trichloroethylene and perchloroethylene, ketones such as acetone and methyl ethyl ketone, and cyclic ethers such as tetrahydrofuran. And alcohols such as methanol, ethanol and isopropanol.

It is appropriate that the carrier generally has a particle size of 20 to 200 [mu] m, expressed in terms of particle size by electron microscopy. When the magnetic material is mainly used, the apparent density can be appropriately adjusted depending on the composition of the magnetic material, the surface structure, and the like, and is generally in the range of 2.4 to 3.0 g / cm ³ . The toner concentration in the two-component developer composed of toner and carrier is suitably about 1 to 20% by weight.

The developer in the present invention can be used in all apparatuses using electrophotographic technology. For example, it can be effectively used in an image forming apparatus provided with a latent image carrier. In an image forming apparatus, a photosensitive drum is usually rotatably arranged as a latent image carrier, and along the rotation direction, a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit are arranged. Devices and the like are sequentially arranged.

  In the developer of the present invention, a latent image carrier is optionally provided with a blocking layer on a conductive substrate roller such as a metal such as aluminum, nickel and chromium, and selenium, zinc oxide, selenium sulfide, amorphous silicon, etc. It is preferably used in an image forming apparatus using an inorganic photosensitive drum provided with a photosensitive layer. Further, those having a photosensitive layer made of amorphous silicon are more preferable. Amorphous silicon includes a-Si, a-SiC, a-SiO, a-SiON, and the like. When using a latent image carrier having a photosensitive layer made of amorphous silicon, it is advantageous to use the action of an abrasive externally added to the non-spherical toner, and prevents image defects such as image flow. can do.

  Further, an image forming apparatus that can advantageously use the developer of the present invention is preferably provided with a polishing means for polishing the surface of the latent image carrier. For example, the cleaning device usually includes a cleaning member such as a magnetic brush or a fur brush that removes toner or paper dust remaining on the surface of the latent image carrier. It is preferable to include an elastic blade, a polishing roller, and the like for rubbing and polishing the surface of the latent image carrier.

  As these, those known in the art can be used.

  The electrophotographic developer of the present invention will be described in detail below.

Production of spherical toner (suspension polymerization method)
80 parts by weight of styrene, 20 parts by weight of 2-ethylhexyl methacrylate, 5 parts by weight of carbon black (MA-100: manufactured by Mitsubishi Chemical Corporation) and 3 parts by weight of low molecular weight polypropylene (YUMEX 100TS: manufactured by Sanyo Chemical Co., Ltd.), charge control agent (Bontron N -07: 2 parts by weight of polymerization initiator 2,2-azobis (2,4-dimethylvaleronitrile) was added to a mixed solution of 2 parts by Orient Chemical Co., Ltd. and 1 part by weight of divinylbenzene (crosslinking agent). It was added to 400 parts by weight of purified water. Furthermore, 5 parts by weight of tribasic calcium phosphate and 0.1 part by weight of sodium dodecylbenzenesulfonate are added as a suspension stabilizer, and the mixture is stirred for 20 minutes at a rotational speed of 7000 rpm using a TK homomixer (manufactured by Special Machine Industries). In a nitrogen atmosphere, a polymerization reaction was carried out at 70 ° C. and 100 rpm for 10 hours to obtain a spherical toner having a shape factor SF-1 of 108 and a shape factor SF-2 of 105 (volume average particle size 8 μm).

When the degree of polymerization progresses about 80%, the polymerization is completed by setting the rotation speed of the TK homomixer to 4000 rpm, whereby the shape factor SF-1 is 112, the shape factor SF-2 is 108, and the volume average particle size is 8 μm. No toner was obtained. Further, when the degree of polymerization progresses about 80%, the polymerization is completed by setting the rotation speed of the TK homomixer to 4500 rpm, so that the shape factor SF-1 is 115, the shape factor SF-2 is 109, and the volume average particle size is 8 μm. A toner was obtained.
Production of irregular shaped toner (suspension polymerization method)
5 parts by weight of carbon black, 10 parts by weight of tribasic calcium phosphate powder (average particle size 0.5 μm), 80 parts by weight of styrene, 20 parts by weight of 2-ethylhexyl methacrylate, 5 parts by weight of carbon black, low molecular weight polypropylene wax (Umex 100TS : Sanyo Chemical Co., Ltd.) 3 parts, 2 parts by weight of charge control agent (Bontron N-07) and 1 part by weight of divinylbenzene (crosslinking agent) were mixed thoroughly by a ball mill.

  Thereafter, 1% by weight of an aluminum coupling agent was added to tricalcium phosphate and stirred for 30 minutes. Furthermore, 2 parts by weight of a polymerization initiator 2,2-azobis (2,4-dimethylvaleronitrile) was added, and this was added to 400 parts by weight of purified water, and further 4 parts by weight of calcium triphosphate and dodecylbenzene as a suspension stabilizer. 0.1 part by weight of sodium sulfonate was added. This was stirred with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at a rotational speed of 8500 rpm for 20 minutes and polymerized at 70 ° C. and 100 rpm for 10 hours in a nitrogen atmosphere to obtain a spherical toner having a volume average particle diameter of 6.0 μm. Got.

  Next, after washing under hydrochloric acid acidity to dissolve the tricalcium phosphate powder, the powder is washed several times with purified water and dried to give a shape factor SF-1 of 110, a shape factor SF-2 of 129, and a volume. An irregularly shaped toner having an average particle diameter of 6.0 μm was obtained.

Further, the shape factor SF-1 is 112 and the shape factor SF-2 is the same as described above except that the addition amount of tricalcium phosphate as a suspension stabilizer is 5 parts by weight and the rotation speed of the TK homomixer is 7800 rpm. 134, an irregularly shaped toner having a volume average particle diameter of 7.0 μm was obtained.
Production of non-spherical toner (grinding method)
100 parts by weight of styrene-acrylic resin, 5 parts of carbon black (MA-100), 3 parts of polypropylene wax and 2 parts by weight of charge control agent (FCA201PS: manufactured by Fujikura Kasei) are premixed with a Henschel mixer and mixed into a twin-screw kneading extruder. Melt kneading, coarse pulverization, fine pulverization (manufactured by Nippon New Match Co., Ltd., airflow pulverizer jet mill IDS-2 type), classification, shape factor SF-1 is 152, shape factor SF-2 No. 159 and a deformed toner having a volume average particle diameter of 7.0 μm were obtained.
Production of Developer For the obtained spherical toner, silica fine particles (REA200: manufactured by Nippon Aerosil Co., Ltd.) and titanium oxide (EC100: manufactured by Titanium Industry Co., Ltd.) in the proportions shown in Table 1 were put into a Henschel mixer, Mixed (3000 rpm, 1 minute).

  Further, silica fine particles (REA200) and titanium oxide (EC100) in the proportions shown in Table 1 were put into a Henschel mixer and mixed (3000 rpm, 1 minute) with the obtained irregular shaped toner.

  The externally added spherical toner and non-spherical toner were charged into a Henschel mixer at a ratio of 80:20 and mixed (3000 rpm, 1 minute).

  Subsequently, the obtained toner mixture was mixed with a ball mill for 20 minutes so that the toner concentration was 5% by weight with respect to a carrier used in a printer (FS-8008N) manufactured by Kyocera Mita, which will be described later. Electrophotographic developers of Examples and Comparative Examples were obtained.

  The shape factor SF-1, the shape factor SF-2, and the volume average particle size of the toner were determined as follows. The shape factor SF-1 and the shape factor SF-2 were measured as follows. A photograph magnified 1000 times to 10000 times using a FE-SEM (S-800) manufactured by Hitachi, Ltd. is taken, and 100 toner images are randomly sampled. The image information is introduced into an image analysis apparatus (Luxex 3) manufactured by Nireco Co., Ltd. via an interface and analyzed, and the values obtained by calculating from the above formulas are the shape factors SF-1 and SF- of the particles in the present invention. 2 was defined. The volume average particle size was measured by measuring the average particle size of 50,000 particles using a Coulter counter TA-II type (manufactured by Coulter Co.) with a 100 μm aperture.

得られた実施例及び比較例の現像剤について、画像濃度、カブリ濃度、クリーニング性ドット再現性、文字中抜け、画像流れ及び選択現像性の評価を行った。その結果を表２に示す。なお、評京セラミタ製のプリンタ（FS-8008N）を用いて実施した。
画像濃度の評価
通常の複写機用普通紙にプリンタの通常の条件設定でベタ画像を含む画像を出力し、反射濃度計（東京電色社製のＴＣ−６Ｄ）を用いて測定した。

The developers of the obtained Examples and Comparative Examples were evaluated for image density, fog density, cleaning dot reproducibility, character dropout, image flow, and selective developability. The results are shown in Table 2. The evaluation was carried out using a Kyocera Mita printer (FS-8008N).
Evaluation of Image Density An image including a solid image was output to normal copying machine plain paper under the normal conditions of the printer, and measurement was performed using a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.).

A: 1.40 or more B: 1.30 or more, less than 1.40 C: 1.00 or more, less than 1.30 D: Less than 1.00 Evaluation of fog density Normal condition setting for ordinary copying machine plain paper Then, an image including a solid image was output, and the image density of a portion without printing was measured using a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.).

A: Less than 0.005 B: 0.005 or more, less than 0.008 C: 0.008 or more, less than 0.011 D: 0.011 or more Evaluation of the cleaning property was performed under the following conditions (normal setting) Is the same).

Blade pressure contact angle: 26 °,
Blade pressure contact force: 2.6 mm,
Rubber thickness: 2.5mm
Encroachment amount: 1.05 mm,
The drum peripheral speed (359.9 mm / sec) was set.

  The cleaning brush was set at the same setting as FS-8008N.

Regarding the cleaning blade setting and the like, the same result was obtained even if it fluctuated within the range of ± 10% of the above-described conditions.
Evaluation of cleaning property A solid band having a toner amount of about 0.7 mg / cm 2 is formed on the latent image carrier, the solid band is transferred onto a transfer paper, and the residual toner is transferred to a cleaning device having a cleaning blade. Moved. Subsequently, the surface of the latent image carrier was cleaned by a cleaning device.

  A cellophane adhesive tape is applied to the surface of the latent image carrier that is downstream of the cleaning blade contact position in the rotational direction of the latent image carrier and cleaned by the cleaning blade, and the adhesive tape is peeled off. Affixed to the surface of a blank paper. Thereafter, the toner density in the adhesive tape attached to the white paper was measured using a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.).

The density when no toner remained on the surface of the latent image carrier was 0.10 to 0.14. When the density reached 0.20 or more, it was determined that the toner remained.
Evaluation of Dot Reproducibility An image of an isolated dot pattern having a small diameter (50 μm) that is difficult to reproduce due to the latent image electric field being easily closed is output, and the dot reproducibility is evaluated.

A: Less than 5 defects / 100 defects B: 6-8 defects / 100 defects C: 9-13 defects / 100 defects D: More than 14 defects / 100 evaluations The omission in characters when output on paper (128 g / m2) was visually evaluated.

      A: There is almost no void.

      B: A slight void is observed.

      C: Some voids are observed.

D: Significant void is seen.
Evaluation of image flow After outputting an image with a printing rate of 5% on 10,000 sheets in a normal environment (25 ° C., 65% RH), the printer is operated for 24 hours in an environment of 32.5 ° C./80%. The whole surface half image (25% 1 dot) was output, and the image flow was confirmed visually. If any image flow occurred, it was determined as x.
Selective developability For the toner in the developing unit before printing and after printing 10,000 sheets, the number of irregularly shaped toner in 300 arbitrary toner particles is measured by the image analyzer, and the ratio of the start time and the ratio after printing The difference was evaluated.
A: Less than 5% B: 5% or more and less than 10% C: 10% or more and less than 20% D: 20% or more When a difference of 10% or more occurs, it was evaluated as nonconforming.

表２から、非球形トナーの外添剤量が、球形トナーの外添剤量よりも多い場合には、非球形トナーの選択現像性を抑制することができることができ、良好な画像形成が行えることが確認された。

From Table 2, when the amount of the external additive of the non-spherical toner is larger than the amount of the external additive of the spherical toner, the selective developability of the non-spherical toner can be suppressed and good image formation can be performed. It was confirmed.

  In addition, when the spherical toner has a volume average particle size larger than that of the non-spherical toner, the development property and transferability of the spherical toner are improved and the adhesion force of the non-spherical toner having a small volume average particle size to the carrier is reduced. Thus, it was confirmed that the selective development of the non-spherical toner can be further suppressed.

  In Comparative Examples 1 and 3 in which the amount of the external additive of the spherical toner is larger than the amount of the external additive of the irregular toner, the spherical toner is more easily developed than the irregular toner, so that the amount of the irregular toner reaching the cleaning portion is small. As a result, the occurrence of poor cleaning was observed.

  In Comparative Examples 2 and 4 in which no abrasive was added to the irregularly shaped toner, the photoconductor was not polished, and thus image flow was observed when used in a high temperature and high humidity environment.

The electrophotographic developer of the present invention can be applied to all of copiers, printers, facsimiles, composite machines and the like using electrophotography.

Claims (3)

  An electrophotographic developer comprising a spherical toner produced by a polymerization method, a toner produced by a polymerization method and having a spherical shape as a basic shape and pores on the surface thereof, or a toner produced by a pulverization method, comprising: The produced spherical toner, the toner produced by the polymerization method and having a spherical shape as a basic shape, and the toner produced by the pulverization method are each surface-treated with an external additive, and the spherical shape is produced by the polymerization method. The amount of the external additive used for the surface treatment of the spherical toner manufactured by the polymerization method is the amount of the external additive used for the surface treatment of the toner having a basic shape and having pores on the surface or the toner manufactured by the pulverization method. An electrophotographic developer characterized by having more than the above. 2. The electrophotographic apparatus according to claim 1, wherein the toner as an external additive is contained only in a toner produced by a polymerization method and having a spherical shape as a basic shape and having pores on its surface or a toner produced by a pulverization method. Developer. 2. The electrophotographic developer according to claim 1, wherein the volume average particle diameter of the spherical toner is larger than the volume average particle diameter of the non-spherical toner.