JP5455967B2 - Two component developer - Google Patents

Description

  The present invention relates to a two-component developer.

  In general, in an image forming method such as electrophotography or electrostatic recording, the surface of an electrostatic latent image carrier (photoconductor) is charged by corona discharge or the like, and then exposed by a laser or the like to form an electrostatic latent image. The electrostatic latent image is developed with toner to form a toner image, and the toner image is transferred to a recording medium to obtain a high quality image. Usually, the toner used for forming the toner image is mixed with a binder resin such as a thermoplastic resin, a colorant, a charge control agent, a release agent, etc., kneaded, pulverized and classified to have an average particle size of 5 to 10 μm. Toner particles are used. For the purpose of imparting fluidity to the toner, controlling the charge amount of the toner, and improving the cleaning property of the toner remaining on the photoreceptor without being transferred, inorganic fine particles such as silica and titanium oxide are used. Powder or the like is externally added to the toner.

  As a developing method using such a toner, a one-component developing method using toner alone as a developer (one-component developer) and a two-component using a developer (two-component developer) in which toner and a carrier are mixed. A development method is known. In the two-component development method using a two-component developer, the carrier charges the toner by frictional charging and also carries the toner, so that the chargeability and the transportability are easy to be relatively stable in the initial stage. There is.

  In a two-component developer used in the two-component development method, a carrier in which a carrier core is coated with a coating agent such as an acrylic resin, a silicon resin, or an epoxy resin has been conventionally used. However, when printing is performed for a long time using a two-component developer containing such a carrier, the ability to charge the toner of the carrier by scraping the coating agent of the carrier or attaching an external additive peeled from the toner to the carrier surface There is a problem that image defects such as fogging easily occur in the formed image.

  For this reason, a two-component developer using a carrier coated with a resin containing a polyamideimide resin has been proposed for the purpose of suppressing the abrasion of the carrier coating agent (Patent Document 1). In addition, a two-component developer including a carrier in which a fluororesin is added to a carrier coat layer has been proposed for the purpose of suppressing adhesion of an external additive peeled from the toner to the carrier surface (Patent Document 2).

JP 2006-163373 A JP 2002-148869 A

  However, the two-component developer described in Patent Document 1 uses a polyamide-imide resin as a carrier coating agent, which is more coated than when an acrylic resin, a silicon resin, an epoxy resin, or the like is used as a carrier coating agent. Although the abrasion of the agent was somewhat improved, the degree of improvement was not sufficient, and further suppression of the abrasion of the coating agent was required.

  The two-component developer described in Patent Document 2 tends to suppress adhesion of the external additive to the carrier due to the flexibility of the fluororesin when the particle size of the external additive is large. However, when the particle diameter of the external additive is small (for example, the average primary particle diameter is 10 nm or less), the external additive itself may be embedded in the fluororesin and the external additive may adhere to the carrier surface. . In addition, since the fluororesin is flexible, there is a problem in that it is easily scraped on the carrier surface when printing is performed for a long time.

  The present invention has been made in view of such circumstances, and when printing over a long period of time, by suppressing the abrasion of the carrier coating agent and the adhesion of the external additive peeled from the toner to the carrier surface, It is an object of the present invention to provide a two-component developer capable of suppressing a decrease in the ability to charge toner of a carrier and preventing image defects such as fog from occurring in a formed image.

  In the two-component developer containing a toner and a carrier, the present inventors assume that the carrier is coated with a coating agent, and by using a coating agent containing an aromatic polyether ketone resin and a fluororesin. The present inventors have found that the above problems can be solved and have completed the present invention. Specifically, the present invention provides the following.

(1) including toner and carrier;
The carrier has a carrier core coated with a coating agent,
The coating agent is a two-component developer containing an aromatic polyether ketone resin and a fluororesin.

  (2) The two-component developer according to (1), wherein the aromatic polyether ketone resin is an aromatic polyether ketone resin, an aromatic polyether ether ketone resin, or a mixture thereof.

  (3) The fluororesin is one or more fluororesins selected from the group consisting of polytetrafluoroethylene, perfluoroalkoxy fluororesin, and tetrafluoroethylene-hexafluoropropylene copolymer, (1 Or a two-component developer according to (2).

  (4) The carrier core according to any one of claims (1) to (3), wherein the carrier core is covered with two layers including an inner layer made of the fluororesin and an outer layer made of the aromatic polyether ketone resin. Two-component developer.

  (5) The two-component developer according to any one of (1) to (4), wherein the carrier is coated with 0.1 to 10% by mass of the coating agent with respect to the mass of the carrier core.

  According to the present invention, when printing is performed for a long period of time, the carrier coating agent is scraped and the external additive peeled from the toner is prevented from adhering to the carrier surface, thereby reducing the ability of the carrier to charge the toner. It is possible to provide a two-component developer that can suppress the occurrence of image defects such as fogging.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

  The two-component developer of the present invention contains a toner and a carrier. Hereinafter, the toner and carrier constituting the two-component developer of the present invention and the method for producing the two-component developer will be described in order.

[toner]
In the toner contained in the two-component developer of the present invention, components such as a colorant, a charge control agent, and a release agent are blended in the binder resin as necessary. The toner contained in the two-component developer may be one having an external additive attached to the surface thereof. Hereinafter, the binder resin, the colorant, the charge control agent, the release agent, the external additive, and the toner manufacturing method will be described in order.

[Binder resin]
The binder resin contained in the toner is not particularly limited as long as it is a resin conventionally used as a binder resin for toner. Specific examples of the binder resin include styrene resin, acrylic resin, styrene acrylic resin, polyethylene resin, polypropylene resin, vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, polyvinyl alcohol resin, vinyl ether. And thermoplastic resins such as styrene resins, N-vinyl resins, and styrene-butadiene resins. Among these resins, styrene acrylic resins and polyester resins are preferable from the viewpoints of dispersibility with respect to the colorant in the toner, chargeability of the toner, and fixing properties with respect to the paper. Hereinafter, the styrene acrylic resin and the polyester resin will be described.

  The styrene acrylic resin is a copolymer of a styrene monomer and an acrylic monomer. Specific examples of the styrene monomer include styrene, α-methylstyrene, vinyl toluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-ethylstyrene, and the like. Specific examples of the acrylic monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, meta Examples include (meth) acrylic acid alkyl esters such as methyl acrylate, ethyl methacrylate, n-butyl methacrylate, and iso-butyl methacrylate.

  As the polyester resin, those obtained by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component can be used. The components used when synthesizing the polyester resin include the following alcohol components and carboxylic acid components.

  Specific examples of the divalent or trivalent or higher alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, Bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, Entaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4- Examples include trivalent or higher alcohols such as butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  Specific examples of the divalent or trivalent or higher carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, or n-butyl succinic 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 Divalent carboxylic acids such as acids, isododecyl succinic acid, isododecenyl succinic acid and the like or alkyl or alkenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid Acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalene Tricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, And trivalent or higher carboxylic acids such as tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empole trimer acid. These divalent or trivalent or higher carboxylic acid components may be used as ester-forming derivatives such as acid halides, acid anhydrides, and lower alkyl esters. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  When the binder resin is a polyester resin, the softening point of the polyester resin is preferably 80 to 150 ° C, and more preferably 90 to 140 ° C.

  As the binder resin, it is preferable to use a thermoplastic resin because it has good fixability. However, not only the thermoplastic resin alone but also a crosslinking agent or a thermosetting resin should be added to the thermoplastic resin. Can do. By introducing a partially crosslinked structure into the binder resin, it is possible to improve the storage stability, form retention, durability and the like of the toner without deteriorating the fixability.

  As the thermosetting resin that can be used together with the thermoplastic resin, for example, an epoxy resin or a cyanate resin is preferable. Specific examples of suitable thermosetting resins include bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, novolac type epoxy resins, polyalkylene ether type epoxy resins, cycloaliphatic type epoxy resins, cyanate resins and the like. It is done. These thermosetting resins can be used in combination of two or more.

  The glass transition point (Tg) of the binder resin is preferably 50 to 65 ° C, and more preferably 50 to 60 ° C. If the glass transition point of the binder resin is too low, the toners may be fused inside the developing unit of the image forming apparatus, or the storage stability may be reduced. May be partly fused. Further, when the glass transition point is too high, the strength of the binder resin is lowered, and the toner is likely to adhere to the latent image carrier (image carrier: photoconductor). If the glass transition point is too high, the toner tends to be difficult to fix well at low temperatures.

  In addition, the glass transition point of binder resin can be calculated | required from the change point of specific heat using a differential scanning calorimeter (DSC). More specifically, it can be determined by measuring an endothermic curve using a differential scanning calorimeter DSC-6200 manufactured by Seiko Instruments Inc. as a measuring device. An endothermic curve obtained by placing 10 mg of a measurement sample in an aluminum pan, using an empty aluminum pan as a reference, and measuring at a measurement temperature range of 25 to 200 ° C. and a temperature increase rate of 10 ° C./min. The glass transition point can be obtained more.

[Colorant]
The toner contained in the two-component developer of the present invention may contain a colorant in the binder resin. When the toner contains a colorant, the toner can be appropriately selected from known pigments and dyes according to the color of the toner particles. Specific examples of suitable colorants to be added to the toner include black pigments such as carbon black, acetylene black, lamp black, and aniline black; yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow , Yellow pigments such as Navels Yellow, Naphthol Yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake; Red Yellow Yellow Lead, Molybdenum Orange, Permanent Orange Orange pigments such as GTR, Pyrazolone Orange, Vulcan Orange, Indanthrene Brilliant Orange GK; Bengala, Cadmium Red, Lead Tan, Mercury Cadmium, Permanent Red 4R, Lithium Red pigments such as Lured, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B; Purple such as Manganese Purple, Fast Violet B, Methyl Violet Lake Pigment: Blue pigment such as bitumen, cobalt blue, alkali blue lake, Victoria blue partially chlorinated, First Sky Blue, Indanthrene Blue BC, etc .; Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake, Final Yellow Green G Green pigments; white pigments such as zinc white, titanium oxide, antimony white, zinc sulfide; barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white, etc. It includes the quality pigments. These colorants may be used in combination of two or more for the purpose of adjusting the toner to a desired hue.

  The amount of the colorant used is not particularly limited as long as the object of the present invention is not impaired. Specifically, 1-10 mass parts is preferable with respect to 100 mass parts of binder resin, and 3-7 mass parts is more preferable.

(Charge control agent)
The toner contained in the two-component developer may contain a charge control agent. The charge control agent improves the stability of the charge level of the toner and the charge rise characteristics that indicate whether the toner can be charged to a predetermined charge level in a short time. Used for gaining purposes. When developing with positively charged toner, a positively chargeable charge control agent is used. When developing with negatively charged toner, a negatively chargeable charge control agent is used.

  The type of the charge control agent is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from charge control agents conventionally used in toners. Specific examples of the positively chargeable charge control agent include pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1, 2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, Azine compounds such as phthalazine, quinazoline, quinoxaline; azine fast red FC, azine fast red 12BK, azine violet BO, azine Direct dyes composed of azine compounds such as Laun 3G, Azin Light Brown GR, Azin Dark Green BH / C, Azin Dep Black EW, and Azin Dee Black 3RL; Nigrosine Compounds such as Nigrosine, Nigrosine Salt, Nigrosine Derivatives; Nigrosine Acid dyes comprising nigrosine compounds such as BK, nigrosine NB, and nigrosine Z; metal salts of naphthenic acid or higher fatty acids; alkoxylated amines; alkylamides; quaternary ammonium salts such as benzylmethylhexyldecylammonium and decyltrimethylammonium chloride It is done. Among these positively chargeable charge control agents, a nigrosine compound is particularly preferable in that a more rapid start-up property can be obtained. These positively chargeable charge control agents can be used in combination of two or more.

  Quaternary ammonium salts, carboxylates, or resins having a carboxyl group as a functional group can also be used as a positively chargeable charge control agent. More specifically, a styrene resin having a quaternary ammonium salt, an acrylic resin having a quaternary ammonium salt, a styrene-acrylic resin having a quaternary ammonium salt, a polyester resin having a quaternary ammonium salt, a carboxylic acid Styrene resin with salt, acrylic resin with carboxylate, styrene-acrylic resin with carboxylate, polyester resin with carboxylate, polystyrene resin with carboxyl group, acrylic with carboxyl group 1 type, or 2 or more types, such as resin, the styrene-acrylic resin which has a carboxyl group, and the polyester-type resin which has a carboxyl group, are mentioned. The molecular weight of these resins is not particularly limited as long as the object of the present invention is not impaired, and may be an oligomer or a polymer.

  Among resins that can be used as a positively chargeable charge control agent, a styrene-acrylic copolymer having a quaternary ammonium salt as a functional group from the viewpoint that the charge amount can be easily adjusted to a value within a desired range. A resin is more preferable. Specific examples of preferable acrylic comonomers to be copolymerized with styrene units in a styrene-acrylic copolymer resin having a quaternary ammonium salt as a functional group include methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic acid. (Meth) such as iso-propyl, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate Examples include alkyl acrylates.

  As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate, dialkyl (meth) acrylamide, or dialkylaminoalkyl (meth) acrylamide through a quaternization step is used. Specific examples of the dialkylaminoalkyl (meth) acrylate include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like. Specific examples of dialkyl (meth) acrylamide include dimethylmethacrylamide, and specific examples of dialkylaminoalkyl (meth) acrylamide include dimethylaminopropylmethacrylamide. Further, hydroxy group-containing polymerizable monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and N-methylol (meth) acrylamide can be used in combination during polymerization.

  Specific examples of the negatively chargeable charge control agent include organometallic complexes and chelate compounds. Examples of organometallic complexes and chelate compounds include acetylacetone metal complexes such as aluminum acetylacetonate and iron (II) acetylacetonate, and salicylic acid metal complexes or salicylic acid systems such as chromium 3,5-di-tert-butylsalicylate. Metal salts are preferable, and salicylic acid metal complexes or salicylic acid metal salts are more preferable. These negatively chargeable charge control agents can be used in combination of two or more.

  The amount of the positively or negatively chargeable charge control agent used is not particularly limited as long as the object of the present invention is not impaired. The amount of the positively or negatively chargeable charge control agent used is typically preferably 1.5 to 15 parts by mass, and 2.0 to 8.0 parts by mass when the total amount of toner is 100 parts by mass. Part is more preferable, and 3.0 to 7.0 parts by weight is particularly preferable. When the amount of the charge control agent used is too small, it is difficult to stably charge the toner to a predetermined polarity, so that the image density of the formed image may be lowered or the image density may not be maintained for a long time. In such a case, the charge control agent is difficult to uniformly disperse, and the formed image is likely to be fogged, or the latent image carrier is easily contaminated. If the amount of charge control agent used is excessive, toner charge failure under high temperature and high humidity is likely to occur due to deterioration of environmental resistance, and as a result, image defects and contamination of the latent image carrier are likely to occur. Become.

  Since the two-component developer of the present invention contains a negatively chargeable fluororesin in the carrier coating agent, the toner can be charged particularly well when the toner contained in the two-component developer is a positively chargeable toner. it can. For this reason, the toner contained in the two-component developer is preferably a positively chargeable toner containing a positively chargeable charge control agent.

〔Release agent〕
The toner may contain a release agent for the purpose of improving fixability and offset resistance. The type of release agent added to the toner is not particularly limited as long as the object of the present invention is not impaired. The mold release agent is preferably a wax, and examples of the wax include polyethylene wax, polypropylene wax, fluororesin-based wax, Fischer-Tropsch wax, paraffin wax, ester wax, montan wax, rice wax and the like. These waxes can be used in combination of two or more. By adding such a release agent to the toner, it is possible to more efficiently suppress the occurrence of offset and image smearing (dirt around the image when the image is rubbed).

  The amount of the release agent used is not particularly limited as long as the object of the present invention is not impaired. The amount of the specific release agent used is preferably 1 to 5 parts by mass with respect to 100 parts by mass of the binder resin. If the amount of the release agent used is too small, the desired effect may not be obtained in terms of suppressing the occurrence of offset and image smearing in the formed image. If the amount of release agent used is excessive, In some cases, the storage stability may be reduced by fusing.

(External additive)
For the purpose of improving the fluidity, storage stability, cleaning properties, etc. of the toner, an external additive may be attached to the surface of the toner.

  The type of external additive is not particularly limited as long as it does not impair the object of the present invention, and can be appropriately selected from external additives conventionally used for toners. Specific examples of suitable external additives include silica and metal oxides such as alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, and barium titanate. These external additives can be used in combination of two or more.

  The particle diameter of the external additive is not particularly limited as long as the object of the present invention is not impaired, and typically 0.01 to 1.0 μm is preferable.

  The volume specific resistance value of the external additive can be adjusted by forming a coating layer made of tin oxide and antimony oxide on the surface of the external additive and changing the thickness of the coating layer and the ratio of tin oxide to antimony oxide. .

  The amount of the external additive used for the toner is not particularly limited as long as the object of the present invention is not impaired. Typically, the amount of the external additive used is preferably 0.1 to 10 parts by mass and more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the toner. When the external additive is used in such an amount, it is easy to obtain a toner excellent in fluidity, storage stability, and cleaning properties.

[Toner Production Method]
The toner used in the present invention is obtained by mixing components such as a colorant, a charge control agent, and a release agent in a binder resin, if necessary, and then melt-kneading, and pulverizing and classifying the obtained kneaded product. Can be manufactured. The melt-kneading apparatus used for the production of the electrostatic image developing toner is not particularly limited, and can be appropriately selected from apparatuses used for melt-kneading thermoplastic resins. Specific examples of the kneading apparatus include a uniaxial or biaxial extruder. The average particle size of the pulverized and classified toner is not particularly limited as long as the object of the present invention is not impaired, but generally 5 to 10 μm is preferable.

  The surface of the toner thus obtained may be treated with an external additive as necessary. The method for treating the toner with the external additive is not particularly limited, and can be appropriately selected from conventionally known methods for treating the external additive. Specifically, the processing conditions are adjusted so that the particles of the external additive are not embedded in the toner base particles, and the processing with the external additive is performed by a mixer such as a Henschel mixer or a Nauter mixer.

[Career]
The carrier contained in the two-component developer of the present invention is one in which a carrier core (carrier core material) is coated with a coating agent containing a specific resin. Hereinafter, the carrier core constituting the carrier and the coating agent will be described in order.

[Carrier Core]
The type of carrier core is not particularly limited as long as it is a carrier core conventionally used for carriers for two-component developers. Specific examples of the carrier core include particles of iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, cobalt, etc., and particles of alloys of these materials with manganese, zinc, aluminum, etc., Particles such as iron-nickel alloy, iron-cobalt alloy, titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, lead titanate, Ceramic particles such as lead zirconate and lithium niobate, particles of high dielectric constant materials such as ammonium dihydrogen phosphate, potassium dihydrogen phosphate and Rochelle salt, resin carriers in which the above magnetic particles are dispersed in a resin, etc. Can be mentioned.

[Coating agent]
The coating agent that coats the carrier core includes an aromatic polyetherketone resin and a fluororesin.

  The aromatic polyether ketone resin is hard and has excellent mechanical strength and wear resistance. For this reason, by using an aromatic polyether ketone-based resin as a component of the coating agent, it is possible to suppress the coating agent from being scraped on the carrier surface and from attaching the external additive to the carrier.

  Moreover, by using a fluororesin as a component of the coating agent, it is possible to satisfactorily fix the aromatic polyether ketone resin that is difficult to adhere to the carrier surface to the carrier core surface. Furthermore, adhesion of the external additive to the carrier can be suppressed by using the fluororesin.

  The total content of the aromatic polyetherketone resin and the fluororesin in the coating agent is not particularly limited as long as the object of the present invention is not impaired, but is preferably 80% by mass or more, more preferably 90% by mass or more. 95 mass% or more is particularly preferable. Other resins that may be included in the coating agent, such as aromatic polyetherketone resin and fluororesin, include (meth) acrylic polymers, styrene polymers, and styrene- (meth) acrylic copolymers. , Olefin polymers (polyethylene, chlorinated polyethylene, polypropylene, etc.), polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, phenol Examples include resins, xylene resins, diallyl phthalate resins, polyacetal resins, amino resins, and the like.

The aromatic polyether ketone resin is not particularly limited as long as it is a resin composed of one or more repeating units selected from the following formulas (1) and (2).
— (— O—Ar ¹ —CO—Ar ² —) — (1)
— (— O—Ar ³ —O—Ar ⁴ —CO—Ar ⁵ —) — (2)
[In Formulas (1) and (2), Ar ^{1 to} Ar ⁵ are each a phenylene group which may have a substituent or a naphthalenediyl group which may have a substituent. The substituent which the phenylene group or naphthalenediyl group may have is an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. ]

  Among aromatic polyether ketone resins, aromatic polyether ketone is a resin composed only of repeating units of formula (1) because it is easily available and has excellent mechanical and thermal properties. Preferred is a resin, an aromatic polyetheretherketone resin which is a resin composed only of the repeating unit of the formula (2), or a mixture thereof, and an aromatic polyetherketone composed only of the repeating unit of the following formula (I) Aromatic polyetheretherketone resin composed only of a resin or a repeating unit of formula (II) is more preferred.

  In the specification of the present application, “aromatic polyether” is used as a general term for resins having an aromatic ether ketone skeleton composed of one or more repeating units selected from the above formulas (1) and (2). The resin is described as “ketone resin”, and the resin composed only of the repeating unit of the above formula (1) is referred to as “aromatic polyether ketone resin”.

  The method for producing the aromatic polyether ketone resin is not particularly limited. For example, an aromatic polyether ketone resin is a diaryl ketone represented by 4-hydroxy-4′-fluorobenzophenone having an aryl group having a hydroxyl group and an aryl group having a fluoro group, between the hydroxyl group and the fluoro group. It is produced by condensation by the nucleophilic substitution reaction of In addition, the aromatic polyetheretherketone resin includes an aromatic diol such as hydroquinone and a diarylketone having two fluoroaryl groups bonded to a carbonyl group such as 4,4′-difluorobenzophenone, a hydroxyl group and a fluoro group. It is produced by condensation through a nucleophilic substitution reaction.

  The fluororesin is not particularly limited as long as it is conventionally used as a carrier coating agent contained in a two-component developer, and can be appropriately selected and used. Specific examples of the fluororesin include polytetrafluoroethylene (PTFE), perfluoroalkoxy fluororesin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyvinylidene fluoride (PVDF), poly And chlorotrifluoroethylene (PCTFE). Among these fluororesins, polytetrafluoroethylene (PTFE), perfluoroalkoxy fluororesin (PFA), and tetrafluoroethylene-6-6 are easily adhered to the carrier core surface and easy to form a coat layer. One or more resins selected from the group consisting of a fluorinated propylene copolymer (FEP) are more preferable.

[Method for producing carrier]
The carrier contained in the two-component developer of the present invention is obtained by coating the carrier core with a coating agent containing an aromatic polyetherketone resin and a fluororesin, and then heat-treating the carrier core coated with the coating agent. In this way, the coating agent is produced by fixing it to the surface of the carrier core. 0.1-10 mass% is preferable with respect to the mass of a carrier core, and, as for the usage-amount of the coating agent at the time of manufacturing a carrier, 1-7 mass% is more preferable.

  The method for coating the carrier core with the coating agent is not particularly limited, and is appropriately selected from methods conventionally used for producing carriers. The method of coating the carrier core with the coating agent may be a wet method in which the solvent is removed after the solution of the coating agent is sprayed onto the carrier core, or a dry method in which the powder of the coating agent is attached to the surface of the carrier core. Either may be sufficient. Aromatic polyether ketone resin is soluble in some solvents such as halogenated benzene and halogenated phenol, but is hardly soluble in common organic solvents, so the coating of the carrier core with the coating agent is More preferably, it is carried out by a dry method. The method for coating the carrier core with the powder of the coating agent is not particularly limited, and examples thereof include a method using a dry coating apparatus such as Nobilta (registered trademark) (manufactured by Hosokawa Micron Corporation).

  Specific examples of the method of coating the carrier core with the powder of the coating agent include a method of coating the carrier core with a single layer with a coating agent comprising a mixture containing an aromatic polyetherketone resin and a fluorine resin, A method of coating with two layers consisting of an inner layer made of a resin and an outer layer made of an aromatic polyether ketone resin can be mentioned.

  When the carrier core is coated with a single layer by a coating agent comprising a mixture comprising an aromatic polyether ketone resin and a fluororesin, it is preferable in that the carrier can be prepared by a single coating operation and the carrier can be easily prepared. . Further, when the carrier core is covered with two layers consisting of an inner layer made of a fluororesin and an outer layer made of an aromatic polyetherketone resin, the amount of the aromatic polyetherketone resin exposed on the surface of the carrier is Since it increases, it is preferable at the point which becomes easy to suppress the abrasion of the coating agent at the time of printing over a long period of time.

  When coating the carrier core with a single layer with a coating agent comprising a mixture comprising an aromatic polyetherketone resin and a fluororesin, using a mixture comprising an aromatic polyetherketone resin and a fluororesin as a coating agent, The carrier core may be coated with a dry coating apparatus.

  When the carrier core is covered with two layers consisting of an inner layer made of a fluororesin and an outer layer made of an aromatic polyetherketone resin, a dry coating apparatus is used to make the fluororesin powder, the aromatic polyetherketone system The carrier core may be coated in the order of resin powder.

  In addition, the coating layer in the case of coating with a single layer, the fluororesin layer in the case of coating the carrier core with 2 layers, and the aromatic polyetherketone-based resin layer are within the range not hindering the object of the present invention. And resins other than aromatic polyetherketone resins. Specific examples of resins other than fluororesins and aromatic polyetherketone resins include (meth) acrylic polymers, styrene polymers, styrene- (meth) acrylic copolymers, olefin polymers (polyethylene). , Chlorinated polyethylene, polypropylene, etc.), polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, phenol resin, xylene resin, diallyl phthalate Examples thereof include resins, polyacetal resins, amino resins, and the like. Further, when the carrier core is coated with two layers, the above-mentioned fluororesin and aromatic polyetherketone system are provided between the fluororesin layer and the aromatic polyetherketone resin layer as long as the object of the present invention is not impaired. Resins other than resins may be present.

  The blending ratio (mass ratio, aromatic polyetherketone resin / fluororesin) of the aromatic polyetherketone resin and the fluororesin in the coating agent is preferably 10/90 to 90/10, and 30/70 to 70. / 30 is more preferable. When the carrier core is coated with a single layer with a coating agent comprising a mixture containing an aromatic polyetherketone resin and a fluororesin, the blending ratio of the aromatic polyetherketone resin and the fluororesin is 40/60 to 70/30 is particularly preferred. Further, when the carrier core is covered with two layers consisting of an inner layer made of a fluororesin and an outer layer made of an aromatic polyetherketone resin, the blending ratio of the aromatic polyetherketone resin and the fluororesin is 30 / 70-60 / 40 is particularly preferred.

  By the above method, the carrier core is coated with the coating agent powder by the dry method, and then the carrier core coated with the coating agent powder is heat-treated to obtain a carrier. Although the temperature of heat processing changes with kinds of resin contained in a coating agent, it is typically performed at 250-320 degreeC. The time for heating the carrier core is not particularly limited, and is typically 30 minutes to 2 hours. By such heat treatment, the coating agent is softened and melted and fixed to the surface of the carrier core.

  The particle diameter of the carrier is not particularly limited as long as the object of the present invention is not impaired, but is preferably 20 to 200 μm, more preferably 30 to 150 μm, as measured by an electron microscope.

The apparent density of the carrier is not particularly limited as long as the object of the present invention is not impaired. The apparent density varies depending on the carrier composition and surface structure, but typically 2.4 to 3.0 g / cm ³ is preferable.

[Method for producing two-component developer]
The production method of the two-component developer is not particularly limited as long as the toner and the carrier can be uniformly mixed. For example, the toner and the carrier may be mixed by a mixing device such as a ball mill. The content of the toner in the two-component developer is preferably 2 to 20% by mass and more preferably 4 to 15% by mass with respect to the mass of the two-component developer. By setting the toner content in the two-component developer within such a range, an appropriate image density is maintained in the formed image, and the toner scattering from the developing device or the like is suppressed to prevent contamination inside the image forming device or transfer paper. Toner adhesion can be suppressed.

  As described above, the two-component developer of the present invention suppresses the abrasion of the carrier coating agent and the adhesion of the external additive peeled from the toner to the carrier surface when printing is performed over a long period of time. A decrease in the ability to charge the toner can be suppressed, and the occurrence of image defects such as fogging can be suppressed. For this reason, the two-component developer of the present invention is suitably used in various image forming apparatuses that employ a two-component development system.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all by the Example.

[Preparation Example 1]
Toners used in the preparation of the two-component developers of Examples and Comparative Examples were prepared according to the following method.
(Manufacture of toner)
100 parts by mass of polyester resin (binder resin, copolymer of bisphenol A and fumaric acid), 4 parts by mass of carbon black (colorant, MA-100 (manufactured by Mitsubishi Chemical Corporation)), Fischer-Tropsch wax (release agent) , FT-100 (manufactured by Nippon Seiki Co., Ltd.)) 3 parts by mass, and quaternary ammonium salt compound (charge control agent, P-51 (manufactured by Orient Chemical Co., Ltd.)) Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) Then, the mixture was melt kneaded with a twin screw extruder to obtain a kneaded product. The obtained kneaded product was cooled and then finely pulverized by an airflow pulverizer. The resulting finely pulverized product was classified by an air classifier to obtain toner base particles having a volume average particle size of 8 μm. 100 parts by mass of the obtained toner base particles and silica fine particles (TG-820 (manufactured by Cabot Corp.)) were mixed for 10 minutes at 3000 rpm using a Henschel mixer (FM-10L (manufactured by Nippon Coke Industries, Ltd.)). The toner was obtained.

[Example 1]
(Carrier production)
Ferrite core carrier (EF-35B (Powder Tech Co., Ltd., center particle diameter 35 μm, saturation magnetization 68 emu / g) 100 parts by mass, polytetrafluoroethylene resin (PTFE) fine particles (L-173 (Asahi Glass Co., Ltd.)) 3 parts by mass and 2 parts by mass of aromatic polyetheretherketone resin (PEEK) fine particles (VICOTE (registered trademark) 704 (manufactured by VICtrex)) were combined with a mechanical coating apparatus (Nobilta (registered trademark) 130 (Hosokawa Micron Corporation). The product was coated at 5000 rpm for 5 minutes, and a ferrite core carrier coated with PTFE fine particles and PEEK fine particles was applied at 280 ° C. in a small high temperature chamber (STH-120 (manufactured by Espec Corp.)). Heat treatment for 1 hour to obtain carrier .

(Manufacture of two-component developer)
In a 1 L capacity plastic container, 1 kg of the obtained carrier and 100 g of the toner obtained in Preparation Example 1 were filled in this order, and then a table-type ball mill rotating stand (V-2ML (manufactured by Irie Shokai Co., Ltd.)) The container was rotated at 100 rpm for 20 minutes, and the carrier and the toner were mixed to obtain a two-component developer. According to the following method, the image density, the fog density, and the charge amount of the toner when the obtained two-component developer was used were evaluated. Table 1 shows the image density, the fog density, and the charge amount of the toner when the two-component developer of Example 1 is used.

<Image density>
Evaluation was performed using a color printer (MFP KM-C3232). The developing device was filled with the two-component developer obtained in Example 1 and the toner obtained in Preparation Example 1 was filled in the toner container, and then a sample image for evaluation was output as an initial image. After outputting the initial image, 3,000 sheets were output at a printing rate of 5%, and then a sample image for evaluation was output. After outputting the sample image, 97,000 sheets were output at a printing rate of 5% (a total of 100,000 sheets were output), and then a sample image for evaluation was output. For the initial image, sample image after output of 3,000 sheets, and sample image after output of 100,000 sheets, the image density of a solid image of 2 × 2 cm provided at three positions on the left side, center, and right side in the sample image Measurement was made and the average value of the image densities at three locations was taken as the image density of the sample image. The image density was measured using a densitometer (RD-19I (manufactured by Gretag Macbeth)). An image density of 1.2 or more was judged as ◯, and an image density of less than 1.2 was judged as ×.

<Fog density>
For the initial image, sample image after output of 3,000 sheets, and sample image after output of 100,000 sheets obtained in the measurement of image density, the image density of the blank portion at the bottom of the solid image and the blank image before output of the image The concentration was measured using a densitometer (RD-19I (manufactured by Gretag Macbeth)). The value obtained by subtracting the image density of the blank paper before image output from the image density of the blank paper portion below the solid image was defined as the fog density. A fog density of 0.020 or less was judged as ◯, and over 0.020 was judged as x.

<Charge amount of toner>
In the measurement of image density, after outputting the initial image, sample image after output of 3,000 sheets, and sample image after output of 100,000 sheets, the developer is taken out, the developer sample is taken, and the suction charge amount measurement The toner charge amount was measured by an apparatus (manufactured by Trek).

[Example 2]
Other than changing the fluororesin from PTFE fine particles to tetrafluoroethylene-hexafluoropropylene copolymer (FEP) fine particles (neoflon (registered trademark) FEP, ND-110 (manufactured by Daikin Industries, Ltd.)) A two-component developer was prepared in the same manner as in Example 1. In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, fog density, and toner charge amount when the two-component developer of Example 2 is used.

Example 3
The two-component developer was changed in the same manner as in Example 1 except that the fluororesin was changed from PTFE fine particles to perfluoroalkoxy fluororesin (PFA) fine particles (Neofluon (registered trademark) PFA (manufactured by Daikin Industries, Ltd.)). Prepared. In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, the fog density, and the toner charge amount when the two-component developer of Example 3 is used.

Example 4
Aromatic polyetherketone resin is changed from aromatic polyetheretherketone resin (PEEK) fine particles (VICOTE (registered trademark) 704 (manufactured by VICtrex)) to aromatic polyetheretherketone resin (PEEK) fine particles (VICOTE (registered trademark)). ) 707 (manufactured by VICtrex)) A two-component developer was prepared in the same manner as in Example 1. In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, the fog density, and the toner charge amount when the two-component developer of Example 4 is used.

Example 5
Aromatic polyetherketone resin is changed from aromatic polyetheretherketone resin (PEEK) fine particles (VICOTE (registered trademark) 704 (manufactured by VICtrex)) to aromatic polyetheretherketone resin (PEEK) fine particles (VICOTE (registered trademark)). ) 708 (manufactured by VICtrex)), a two-component developer was prepared in the same manner as in Example 1. In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, the fog density, and the toner charge amount when the two-component developer of Example 5 is used.

Example 6
A two-component developer was prepared in the same manner as in Example 1 except that the carrier was prepared according to the following method. In the same manner as in Example 1, the image density, the fog density, and the charge amount of the toner when the obtained two-component developer was used were evaluated. Table 1 shows the image density, the fog density, and the charge amount of the toner when the two-component developer of Example 6 is used.

(Carrier production)
Ferrite core carrier (EF-35B (Powder Tech Co., Ltd., center particle diameter 35 μm, saturation magnetization 68 emu / g) 100 parts by mass, polytetrafluoroethylene resin (PTFE) fine particles (L-173 (Asahi Glass Co., Ltd.)) 3 parts by mass was added to a mechanical coating apparatus (Nobilta (manufactured by Hosokawa Micron Co., Ltd.)), and coating was carried out for 3 minutes, followed by aromatic polyetheretherketone resin (PEEK) in the mechanical coating apparatus. 2 parts by mass of fine particles (VICOTE (registered trademark) 704 (manufactured by VICtrex)) was added into a mechanical coating apparatus (Nobilta (manufactured by Hosokawa Micron Co., Ltd.)) and coated for 2 minutes. The ferrite core carrier coated with Performing heat treated for 1 hour at 280 ° C. by members (STH-120 (manufactured by ESPEC Corporation)), to obtain a carrier.

Example 7
Two-component development in the same manner as in Example 1 except that the amount of PTFE fine particles used is changed from 3 parts by weight to 1.5 parts by weight and the amount of PEEK fine particles used is changed from 2 parts by weight to 3.5 parts by weight. An agent was prepared. In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, fog density, and toner charge amount when the two-component developer of Example 7 is used.

Example 8
A two-component developer was prepared in the same manner as in Example 1 except that the amount of PTFE fine particles was changed from 3 parts by weight to 1 part by weight and the amount of PEEK fine particles was changed from 2 parts by weight to 4 parts by weight. . In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, the fog density, and the toner charge amount when the two-component developer of Example 8 is used.

Example 9
A two-component developer was prepared in the same manner as in Example 1 except that the amount of PTFE fine particles used was changed from 3 parts by weight to 4 parts by weight and the amount of PEEK fine particles used was changed from 2 parts by weight to 1 part by weight. . In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, the fog density, and the charge amount of the toner when the two-component developer of Example 9 is used.

[Comparative Example 1]
A two-component developer was prepared in the same manner as in Example 1 except that the PEEK fine particles were changed to nylon fine particles (SP-500 (manufactured by Toray Industries, Inc.)). In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, the fog density, and the toner charge amount when the two-component developer of Comparative Example 1 is used.

[Comparative Example 2]
A two-component developer was prepared in the same manner as in Example 1 except that the PEEK fine particles were changed to silicon resin fine particles (840 Resin (manufactured by Dow Corning Toray)). In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, the fog density, and the toner charge amount when the two-component developer of Comparative Example 2 is used.

[Comparative Example 3]
A two-component developer was prepared in the same manner as in Example 1, except that the PTFE fine particles were changed to styrene acrylic resin fine particles (FS-201 (manufactured by Nippon Paint Co., Ltd.)). In the same manner as in Example 1, when using the obtained two-component developer, the image density, the fog density, and the toner charge amount were evaluated. Table 1 shows the image density, the fog density, and the toner charge amount when the two-component developer of Comparative Example 3 is used. Note that, after the output of 3,000 sheets, fogging and a decrease in the charge amount of the toner occurred, and thus the evaluation after the output of 100,000 sheets was not performed.

  According to Table 1, according to the two-component developer using a carrier in which the carrier core is coated with a coating agent containing an aromatic polyetherketone resin and a fluororesin, 3,000 sheets and 100,000 sheets It can be seen that there is no significant reduction in toner charge even when printing is performed continuously. That is, in the two-component developers of Examples 1 to 9, the carrier's ability to charge the toner is significantly reduced due to scraping of the carrier coating agent and adhesion of the external additive peeled from the toner to the carrier. Not. For this reason, according to the two-component developers of Examples 1 to 9, even when printing is performed for a long period of time, it is easy to form an image having a good density without causing fogging.

  In addition, when Examples 1 and 7 are compared with Example 8, the ratio of the amount of aromatic polyetherketone resin used to the amount of fluororesin (aromatic polyetherketone resin / fluororesin) is When the ratio exceeds 70/30, it can be seen that the fog density is slightly increased when 3,000 sheets are continuously printed. Further, when Example 1 is compared with Example 9, the ratio of the amount of aromatic polyether ketone resin used to the amount of fluorine resin (aromatic polyether ketone resin / fluorine resin) is 30/70. It can be seen that the image density is slightly lowered when 3,000 sheets are continuously printed. From these, the ratio (mass ratio, aromatic polyetherketone resin / fluororesin) of the amount of the aromatic polyetherketone resin used and the amount of the fluororesin used in the carrier coating agent is 30/70 to 70. It can be seen that / 30 is more preferable.

  On the other hand, according to Comparative Examples 1 and 2, when the coating agent contains a fluororesin but does not contain an aromatic polyetherketone resin, the charge amount of the toner when 3,000 sheets are continuously printed It can be seen that fogging is likely to occur.

  Further, according to Comparative Example 3, even when the coating agent contains an aromatic polyetherketone resin, when the fluorocarbon resin is not included, it is difficult to charge the toner well from the beginning, and fog is likely to occur. I understand. It can also be seen that when 3,000 sheets are continuously printed, the fog density is significantly increased and the toner charge amount is decreased with respect to the initial value.

Claims (5)

Including toner and carrier,
The carrier has a carrier core coated with a coating agent,
The coating agent is a two-component developer containing an aromatic polyether ketone resin and a fluororesin.   The two-component developer according to claim 1, wherein the aromatic polyether ketone resin is an aromatic polyether ketone resin, an aromatic polyether ether ketone resin, or a mixture thereof.   The fluororesin is one or more fluororesins selected from the group consisting of polytetrafluoroethylene, perfluoroalkoxy fluororesin, and tetrafluoroethylene-hexafluoropropylene copolymer, or The component developer according to 2.   The two-component developer according to any one of claims 1 to 3, wherein the carrier core is covered with two layers including an inner layer made of the fluororesin and an outer layer made of the aromatic polyetherketone resin.   The two-component developer according to any one of claims 1 to 4, wherein the carrier is coated with 0.1 to 10% by mass of the coating agent with respect to the mass of the carrier core.