JP2010014947A - Toner for developing electrostatic latent image and image forming process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner for developing an electrostatic latent image, which maintains excellent toner fixability at low temperature and excellent characteristics when storing it and maintains satisfactory electrostatic charging property even under high temperature and high humidity, and to provide an image forming process by use of the toner. <P>SOLUTION: This toner for developing an electrostatic latent image is formed by at least a resin having 1-20 mass% monomer unit expressed by general formula (1) (wherein, n is an integer of 2-5), and coloring agent. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrostatic latent image developing toner and an image forming method using the same.

  In recent years, a technical problem that has been taken up as a major problem in the electrostatic latent image developing system is to achieve high speed and energy saving while maintaining high image quality.

  When considering the above countermeasures, the fixing process is a process that has an influence on image quality and is greatly involved in speeding up and energy saving, and how to develop an electrostatic latent image developing toner suitable for speeding up and energy saving (simply simply Development of the toner (sometimes called toner) is an important concern of each company.

  Conventionally, lowering the softening point of a resin has been generally adopted as a measure for achieving high-speed fixing. However, in this method, although the fixing temperature is lowered, the glass transition temperature of the resin is lowered at the same time, so that a so-called blocking phenomenon occurs while the toner is stored in the toner container or in the developing device. Unless it becomes a practical problem.

  In order to solve the problem, various proposals have been made to improve the blocking property by forming a core-shell structure and using a resin having a high glass transition temperature in the shell portion. However, although this method can improve the storage stability, the adhesion of the shell to the paper is lowered, so that the fixing property cannot reach a sufficient level. That is, a big problem remains in lowering the fixing temperature.

  As a technique for achieving low-temperature fixing without adopting a core-shell structure, for example, as shown in Patent Document 1, a technique using crystalline polyester is disclosed. However, this also has a problem that the viscosity in the melted state is low, and an offset at the time of fixing is likely to occur, and the balance between the reduction of the fixing temperature and the offset property cannot be improved at present.

Further, a method for improving the offset at the time of fixing by improving the viscosity of the resin by ionic crosslinking has been proposed for a long time. For example, a method of ion-crosslinking carboxyl group components in an acrylic resin is known, but it cannot sufficiently improve the low-temperature fixability itself, and further causes a decrease in charge amount in a high-temperature and high-humidity environment. It is also known that there is. As described above, the present situation is that there still remains a big problem in producing a toner having truly low-temperature fixability.
JP 2008-1112074 A

  The present invention provides a toner for developing an electrostatic latent image and an image forming method capable of maintaining both low-temperature fixability and storage characteristics of the toner and maintaining good chargeability even in a high-temperature and high-humidity environment. There is to do.

  As a result of intensive studies, the inventors of the present invention have adopted a resin having a specific structure in order to impart an adhesive function to paper to the resin itself and to further improve the properties during toner storage. I found that I could solve the problem.

(1)
An electrostatic latent image developing toner comprising at least a resin and a colorant, wherein the resin contains 1 to 20% by mass of a monomer unit represented by the following general formula (1): Toner.

However, n = 2 to 5 (2)
The toner for developing an electrostatic latent image according to (1), wherein the toner is ion-crosslinked with polyvalent metal ions.

(3)
An image forming method, wherein a toner image produced using the electrostatic latent image developing toner according to (1) or (2) is fixed by a contact heating fixing device.

  According to the present invention, there are provided a toner for developing an electrostatic latent image and an image forming method capable of maintaining both low-temperature fixability and storage characteristics of the toner and maintaining good chargeability even in a high-temperature and high-humidity environment. can do.

  Hereinafter, the compound used in the present invention and the image forming apparatus used in the image forming method will be further described.

  The toner resin containing the monomer unit represented by the general formula (1) used in the present invention can be obtained by using a monomer represented by the following “Chemical Formula 2” and converting it to a resin by radical polymerization.

  However, it is preferable that the integer of n = 2-5, especially the hydroxyl group couple | bonded as a substituent with the benzene ring is adjacent.

  Furthermore, in the reaction for preparing the resin, there is also a method in which a hydroxyl group is alkoxylated and subjected to a radical polymerization reaction, followed by demethanolation and a hydroxylation method. By using this method, a radical reaction can be stably performed. Can be advanced.

  This monomer can form the toner resin of the present invention by forming a copolymer with a polymerizable monomer described later. In this case, the present monomer unit is contained in an amount of 1 to 20% by mass ratio. When this structural unit is less than 1% by mass, the effect such as fixing ability is small, and when it exceeds 20% by mass, the effect such as fixing property can be sufficiently exerted, but the hydroxyl group is excessively present. As a result, there is a tendency to cause problems in maintaining the chargeability in a high temperature and high humidity environment. More preferably, it is 3-10 mass%.

  Since the resin of the present invention is a resin having a hydroxyl group, the chemical affinity for paper fibers can be increased. As a result, the adhesion to paper is improved and the low-temperature fixability is improved. Estimated. Further, when the toner is produced by a polymerization method described later, ion crosslinking can be provided on the toner surface by reacting with a polyvalent metal ion in an aqueous medium. As a result, the resin existing on the outermost surface can be made into a crosslinked structure, and as a result, the glass transition temperature can be increased microscopically, so that the storage stability can be improved. Furthermore, in the resin structure of the present invention, since the ester group is not present in the vicinity and is a hydroxyl group directly connected to an aromatic group having high hydrophobicity, it is difficult to cause charge leakage even in a high temperature and high humidity environment. It is estimated that the chargeability can be stably maintained even in a high temperature and high humidity environment.

[Monomer unit copolymerized with general formula (1)]
Examples of the polymerizable monomer (monomer) that can be used in combination with the monomer represented by the general formula (1) of the present invention in order to obtain a resin constituting the toner include styrene, o-methylstyrene, and m-methyl. Styrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p- Styrene or styrene styrene derivatives such as n-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene; methyl methacrylate, ethyl methacrylate, methacrylic acid n-butyl, isopropyl methacrylate, isobutyl methacrylate, methacrylic acid -Methacrylate derivatives such as butyl, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate; methyl acrylate, acrylic acid Acrylic esters such as ethyl, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate Derivatives; Olefins such as ethylene, propylene and isobutylene; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride and vinylidene fluoride; Propio Vinyl esters such as vinyl acetate, vinyl acetate and vinyl benzoate; Vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone; N-vinylcarbazole, N -N-vinyl compounds such as vinyl indole and N-vinyl pyrrolidone; vinyl compounds such as vinyl naphthalene and vinyl pyridine; vinyl monomers such as acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide Can be mentioned.

  These vinyl monomers can be used alone or in combination of two or more.

  It is also preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer. The polymerizable monomer having an ionic dissociation group has, for example, a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group, and specifically includes acrylic acid, methacrylic acid, maleic acid. Acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate And 3-chloro-2-acid phosphooxypropyl methacrylate.

  Furthermore, as a polymerizable monomer, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl A binder resin having a crosslinked structure can also be obtained using a polyfunctional vinyl such as glycol diacrylate.

(Polymerization initiator)
The resin of the present invention can be polymerized using a radical polymerization initiator.

  In the case of using the suspension polymerization method, an oil-soluble radical polymerization initiator can be used. As the oil-soluble polymerization initiator, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2 ′ -Azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile, etc. Azo or diazo polymerization initiator, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4- Dichlorobenzoyl peroxide, lauroyl peroxide, 2 Peroxide polymerization initiators such as 2-bis- (4,4-t-butylperoxycyclohexyl) propane and tris- (t-butylperoxy) triazine, polymer initiators having a peroxide in the side chain, etc. Can be mentioned.

  Further, in the solution polymerization method, a method in which the above-mentioned polymerizable monomer is dissolved in toluene, xylene, ethyl acetate, or methyl ethyl ketone, and then the above-described polymerization initiator is added to cause a polymerization reaction.

  In the case of using the miniemulsion polymerization aggregation method or the emulsion polymerization aggregation method, a water-soluble radical polymerization initiator can be used, and the water-soluble radical polymerization initiator includes persulfates such as potassium persulfate and ammonium persulfate. Azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide, and the like.

  Furthermore, a polymerization method such as an anionic polymerization method or a cationic polymerization method may be used. For example, in the case of the anionic polymerization method, a method using a metal alkyl compound such as butyl lithium or ethyl lithium as the catalyst can be mentioned.

[Chain transfer agent]
Furthermore, when manufacturing resin of this invention, molecular weight can be adjusted using the chain transfer agent generally used.

  The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as n-octyl mercaptan, n-decyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionate, terpinolene, carbon tetrabromide. And α-methylstyrene dimer and the like are used.

  Moreover, what is necessary is just to make a polyvalent metal ion act in order to carry out ion bridge | crosslinking. Specific examples of the divalent metal include magnesium and calcium. Examples of the trivalent metal include aluminum, chromium and iron. Further, manganese and the like can be used. These metals can form ion bridges by acting in an ionized state.

  For example, magnesium chloride, magnesium sulfate, calcium chloride, calcium carbonate, aluminum chloride, polyaluminum hydroxide, polyaluminum chloride, chromic acid, chromium lactate, iron sulfate, iron hydroxide, manganese oxide and the like may be used.

[Toner production method, etc.]
A method for producing a toner using the resin of the present invention is not particularly limited, and a pulverization method, a suspension polymerization method, a miniemulsion polymerization aggregation method, an emulsion polymerization aggregation method, a dissolution suspension method, and other methods. A publicly known method etc. can be mentioned.

  For example, in the case of the pulverization method, the resin of the present invention and other resins as necessary, as well as the colorant described later, and further the components necessary for constituting the toner such as a release agent and a charge control agent are dry-type. Next, the mixture is kneaded by a kneading apparatus such as a twin screw extruder, coarsely pulverized and finely pulverized, and colored particles are obtained through a classification step. Thereafter, there is a method of obtaining a toner by adding a fluidizing agent or a cleaning aid, which will be described later.

  A Henschel mixer or V-type mixer can be used for dry mixing, and the pulverizer may be any of an I-type pulverizer, a jet pulverizer, a mechanical pulverizer such as a kryptron or a turbo pulverizer. . After classification, the toner of the present invention can be obtained. As the toner, the volume-based median diameter measured by Coulter Counter Multisizer is 3.0 to 10.0 μm, preferably 4.0 to 8. It is preferable that the thickness is 0.0 μm.

  Next, an example of using a suspension polymerization method as a method for producing a toner using the resin of the present invention will be described. A monomer constituting the resin of the present invention and a radically polymerizable monomer, a polymerization initiator, a colorant and, if necessary, a release agent, a charge control agent, a chain transfer agent are mixed, a sand grinder, an SC mill, etc. Disperse the colorant, release agent, etc. in the monomer using a disperser that uses the above media. Next, the dispersion is dispersed in water containing a dispersion stabilizer in water using high-speed shearing to form oil droplets corresponding to the toner particle size. Thereafter, the mixture is heated to polymerize the monomer by a suspension polymerization reaction. After completion of the polymerization reaction, the dispersion stabilizer in water is removed, filtered and dried to obtain colored particles. Thereafter, as in the case of the above-described pulverization method, a fluidizing agent and a cleaning aid described later are added to obtain a toner.

  In the case of this suspension polymerization method, a resin may be separately synthesized in advance using a monomer represented by the general formula (1) of the present invention, and dissolved in a radical polymerizable monomer.

  Furthermore, as an example of a method for producing a toner using the resin of the present invention, an example in which an association method is used will be described. In this method, resin particles and the like are aggregated and fused in an aqueous medium to form a toner.

  The resin of the present invention is prepared by emulsion polymerization to obtain resin particles. Alternatively, the resin of the present invention is dissolved in a solvent and then dispersed in an aqueous medium to form resin particles. In this case, in addition to the resin of the present invention, other resins may be included. In this case, the resin particles have a number average primary particle size of 50 to 1000 nm, preferably 100 to 500 nm. A release agent or a colorant may be included in the resin particles. Subsequently, the colorant particles prepared separately, and if necessary, mixed with release agent particles or charge control agent particles in an aqueous medium, then agglomerated with a salting-out agent, and further fused by heating to grow particles. And shape control to adjust the colored particles. Thereafter, as in the case of the above-described pulverization method, a fluidizing agent and a cleaning aid described later are added to obtain a toner.

  Any of the above methods may be employed in the production of the toner of the present invention.

[Colorant]
As the colorant constituting the toner of the present invention, a known inorganic or organic colorant can be used. Specific colorants are shown below.

  Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black and lamp black, and magnetic powder such as magnetite and ferrite.

  Examples of the colorant for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48; 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the colorant for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, and the like.

  Examples of the colorant for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15; 2, C.I. I. Pigment blue 15; 3, C.I. I. Pigment blue 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.

  The above colorants can be used alone or in combination of two or more.

  The addition amount of the colorant is in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

  As the colorant, a surface-modified one can also be used. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.

Next, examples of the release agent usable in the toner according to the present invention include the following.
(1) Polyolefin wax Polyethylene wax, polypropylene wax, etc. (2) Long chain hydrocarbon wax, paraffin wax, sazol wax, etc. (3) Dialkyl ketone wax, distearyl ketone, etc. (4) Ester wax Carnauba wax, Montan Wax, trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerol tribehenate, 1,18-octadecanediol di Stearate, trimellitic trimellitic acid, distearyl maleate, etc. (5) Amide wax Ethylenediamine dibehenyl amide, trimellitic acid triste Riruamido like melting points of these release agents is usually 40-125 ° C., preferably from 50 to 120 ° C., more preferably from 60 to 90 ° C.. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the content of the release agent in the toner is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass.

[Charge control agent]
The toner particles constituting the toner of the present invention may contain a charge control agent as necessary. Various known compounds can be used as the charge control agent.

  Examples thereof include azo metal complexes, salicylic acid metal salts or metal complexes, calixarene, and quaternary ammonium salts.

  Next, the toner according to the present invention is manufactured by adding particles such as inorganic fine particles and organic fine particles having a number average primary particle size of 4 to 800 nm as external additives (= external additives) in the production process. Can be done.

  By adding the external additive, the fluidity and chargeability of the toner are improved, and the cleaning property is improved. The type of the external additive is not particularly limited, and examples thereof include the following inorganic fine particles, organic fine particles, and lubricants.

  As the inorganic fine particles, conventionally known fine particles can be used. For example, silica, titania, alumina, strontium titanate fine particles and the like are preferable. Moreover, what hydrophobized these inorganic fine particles as needed can also be used.

  Specific examples of the silica fine particles include commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150 manufactured by Hoechst, H -200, commercially available products TS-720, TS-530, TS-610, H-5, MS-5 and the like manufactured by Cabot Corporation.

  As the titania fine particles, for example, commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercially available products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc. are mentioned.

  Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. Specifically, homopolymers such as styrene and methyl methacrylate and copolymers thereof can be used.

  Further, a lubricant can be used to further improve the cleaning property and transfer property, and examples thereof include the following higher fatty acid metal salts. That is, salts of zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, salts of manganese, iron, copper, magnesium, etc., zinc palmitate, salts of copper, magnesium, calcium, etc., linoleic acid And salts of zinc and calcium of ricinoleic acid.

  The addition amount of these external additives and lubricants is preferably 0.1 to 10.0% by mass with respect to the whole toner. Examples of the method for adding external additives and lubricants include methods using various known mixing devices such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

(Developer)
The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When the toner of the present invention is used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be mentioned. Any of them can be used. In the case where the toner of the present invention is used as a two-component developer, the carrier may be a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. In particular, ferrite particles are preferable. As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a resin dispersion type carrier in which magnetic fine powder is dispersed in a binder resin, or the like may be used.

  The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, silicon resins, ester resins, and fluorine-containing polymer resins. Moreover, it does not specifically limit as resin which comprises a resin dispersion type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used.

  A preferable carrier is a coated carrier coated with a styrene-acrylic resin-based resin as a coating resin from the viewpoint of prevention of detachment of external additives and durability.

  The volume average particle size of the carrier is preferably 20 to 100 μm, more preferably 25 to 80 μm. The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

[Image Forming Apparatus Used in Image Forming Method of Present Invention]
In particular, the toner of the present invention can be suitably used in an image forming method in which a transfer material on which a toner image is formed is fixed in a contact heating type fixing device.

  Preferred examples of the contact heating method include a heat pressure fixing method, a heat roll fixing method, and a pressure heating fixing method in which fixing is performed by a rotating pressure member including a fixedly arranged heating body.

  In the fixing method of the hot roll fixing method, usually, an upper roller provided with a heat source inside a metal cylinder made of iron or aluminum whose surface is coated with fluororesin, etc., and a lower roller formed of silicone rubber or the like Is used.

  As the heat source, a linear heater is used, and the surface temperature of the upper roller is heated to about 120 to 200 ° C. by this heater. A pressure is applied between the upper roller and the lower roller, and the lower roller is deformed by this pressure, so that a so-called nip is formed in the deformed portion. The width of the nip is 1 to 10 mm, preferably 1.5 to 7 mm. The fixing linear velocity is preferably 40 mm / sec to 600 mm / sec. If the nip width is too small, heat cannot be uniformly applied to the toner, and there is a risk of uneven fixing. On the other hand, if the nip width is too large, melting is accelerated, Since the melt viscosity of the toner is lowered, there is a possibility that fixing offset occurs.

  The fixing device may be provided with a cleaning mechanism. Examples of the cleaning mechanism include a mechanism for supplying silicone oil to the upper roller or the film member, and a mechanism for cleaning with a pad, roller, or web impregnated with silicone oil. As the silicone oil, polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, or the like can be used. Furthermore, siloxane containing fluorine can also be suitably used.

[Transfer material]
The transfer material on which the image of the toner of the present invention is formed is a support for holding the toner image, and specifically, coating such as plain paper, fine paper, art paper or coated paper from thin paper to thick paper. Various kinds of printed paper, commercially available Japanese paper, postcard paper, plastic films for OHP, cloth, and the like can be used, but the invention is not limited to these.

  Next, representative embodiments will be shown to further explain the present invention, but of course the scope of the present invention is not limited thereto.

[Production of toner]
Example 1
100 parts by mass of a resin containing 5% by mass of structural units having a hydroxyl group at the meta and para positions of the benzene ring in the general formula (1), 70% by mass of styrene units, and 25% by mass of butyl acrylate units; 6 parts by mass of behenyl behenate, 8 parts by mass of carbon black and 1 part by mass of zinc oxide were mixed with a Henschel mixer, melt-kneaded with a twin screw extruder, then pulverized with a mechanical pulverizer, and further classified. Thus, colored particles having a volume-based median diameter of 6.8 μm were obtained. Next, 1 part by mass of hydrophobic silica (number average primary particle size = 12 nm) was added and mixed with a Henschel mixer to obtain the toner of the present invention. This is designated as Toner 1 of the present invention.

(Example 2)
A 5 L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device was charged with a solution prepared by dissolving 8 g of sodium dodecyl sulfate in 3 L of ion-exchanged water and stirred at a stirring speed of 230 rpm under a nitrogen stream. The internal temperature was raised to 80 ° C. After the temperature rise, a solution in which 10 g of potassium persulfate was dissolved in 200 g of ion-exchanged water was added, and the temperature was again adjusted to 80 ° C., 480 g of styrene, 250 g of n-butyl acrylate, 68.0 g of methacrylic acid, 3,4-dihydroxystyrene Polymerization was performed by adding a polymerizable monomer solution consisting of 9 g and 16.0 g of n-octyl-3-mercaptopropionate over 1 hour, followed by heating and stirring at 80 ° C. for 2 hours to obtain resin particles ( A resin particle dispersion containing 1) was prepared.

  Separately, 70 g of carbon black “Regal 330R” (manufactured by Cabot) was gradually added while stirring a solution of 15 g of sodium dodecyl sulfate dissolved in 500 ml of ion-exchanged water. A dispersion liquid Q of colorant fine particles was prepared by performing a dispersion treatment using a technique manufactured by Technic Co., Ltd. The particle diameter of the colorant fine particles in the dispersion liquid Q of the colorant fine particles was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), and the volume-based median diameter was 110 nm. It was.

  300 g of the resin particle dispersion in terms of solid content, 1400 g of ion-exchanged water, and 120 g of the dispersion of the colorant fine particles are placed in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device. A solution prepared by dissolving 3 g of sodium polyoxyethylene-2-dodecyl ether sulfate in 120 ml of ion-exchanged water was prepared, the temperature of the solution was adjusted to 30 ° C., and a 5 mol / L sodium hydroxide aqueous solution was added to adjust the pH to 10 Adjusted. Next, an aqueous solution in which 35 g of magnesium chloride was dissolved in 35 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring, and the temperature was raised after holding for 3 minutes. The particle growth reaction was continued while maintaining the temperature at 90 ° C. In this state, the particle size of the agglomerated particles is measured by “Coulter Multisizer 3”, and when the desired particle size is reached, an aqueous solution in which 150 g of sodium chloride is dissolved in 600 ml of ion-exchanged water is added to increase particle growth. Further, the mixture is heated and stirred at a liquid temperature of 98 ° C. as a ripening step, and the fusion between the particles is advanced until the average circularity becomes 0.965 as measured by “FPIA-2100”. By orienting the resin to the surface side of the aggregated particles and the hydrophobic resin to the inside of the aggregated particles, toner particles having a core-shell structure are formed, and then cooled to a liquid temperature of 30 ° C., and hydrochloric acid is added The pH was adjusted to 4.0 and stirring was stopped.

  The toner particles produced in the above process are solid-liquid separated with a basket type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a wet cake of toner particles. Was washed with ion exchange water at 45 ° C. until the electrical conductivity of the filtrate reached 5 μS / cm using the basket-type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). Drying to 5% by mass gave toner particles.

  To the toner particles, 1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added and mixed with a Henschel mixer. Inventive toner 2 was produced.

  The shape and particle size of these toner particles did not change depending on the addition of hydrophobic silica and hydrophobic titanium oxide.

(Example 3)
A toner of the present invention was obtained in the same manner as in Example 2, except that the amount of 3,4-dihydroxystyrene added was 25 g. This is designated as Toner 3 of the present invention.

Example 4
A toner of the present invention was obtained in the same manner as in Example 2, except that the amount of 3,4-dihydroxystyrene added was 60 g. This is designated as Toner 4 of the present invention.

(Example 5)
A toner of the present invention was obtained in the same manner as in Example 2, except that the amount of 3,4-dihydroxystyrene added was 85 g. This is designated as Toner 5 of the present invention.

(Example 6)
A toner of the present invention was obtained in the same manner as in Example 2, except that the amount of 3,4-didihydroxystyrene added was 120 g. This is designated as Toner 6 of the present invention.

(Example 7)
A toner of the present invention was obtained in the same manner as in Example 2, except that the amount of 3,4-dihydroxystyrene added was 190 g. This is designated as Toner 7 of the present invention.

(Example 8)
A toner of the present invention was obtained in the same manner as in Example 2, except that 85 g of 3,4,5-trihydroxystyrene was used instead of 3,4-dihydroxystyrene. This is designated as Toner 8 of the present invention.

(Comparative Example 1)
A toner for comparison was obtained using the same resin as in Example 1 except that 3,4-dihydroxystyrene was not used. This is designated as comparative toner 1.

(Comparative Example 2)
A toner for comparison was obtained using the same resin as in Example 2 except that 3,4-dihydroxystyrene was not used. This is designated as comparative toner 2.

(Comparative Example 3)
A toner for comparison was obtained using the same resin as in Example 2 except that 220 g of 3,4-dihydroxystyrene was used. This is referred to as comparative toner 3.

  The compositions of the inventive toners 1 to 8 and comparative toners 1 to 3 are summarized in “Table 1” below.

St: Styrene BA: Butyl acrylate MAA: Methyl methacrylate General formula (1): Monomer corresponding to general formula (1) Content:% by mass
[Manufacture of developer]
Each of the inventive toners 1 to 8 and the comparative toners 1 to 3 is mixed with a silicone carrier-coated ferrite carrier having a volume average particle diameter of 60 μm so that the toner concentration becomes 6% by mass, thereby developing the present invention. Agents 1 to 8 and Comparative developers 1 to 3 were prepared.

  Each of the developers 1 to 8 of the present invention and the developers 1 to 3 for comparison obtained as described above is mounted with the following fixing device on a digital copying machine “bizhub PRO 1050” (manufactured by Konica Minolta). A live-action test was conducted using and the following evaluations were made.

(Fixability evaluation)
It is a thing of the contact heating system shown in FIG. 2, The concrete structure is as follows. A heating roller in which the surface of a cored bar (inner diameter: 40 mm, wall thickness: 1.0 mm, total width: 310 mm) made of a cylindrical aluminum alloy is coated with PTFE (tetrafluoroethylene) at a thickness of 120 μm, and a heater is built in the center. And a pressure roller formed by coating the surface of a cored bar made of cylindrical iron (inner diameter 40 mm, wall thickness 2.0 mm) with sponge silicone rubber (Asker C hardness 48 °, thickness 2 mm), 150 N And a fixing nip portion having a width of 5.8 mm is formed.

  The fixing temperature of this fixing device was changed in units of 10 ° C. from 120 ° C. to 210 ° C., and the linearity was set to 240 mm / sec.

Evaluation uses A4 size fine paper (64 g / m ² ) “J paper” (manufactured by Konica Minolta), prints a solid black image with a width of 10 mm at a position 2 mm from the tip, and an offset occurs on the white background Whether or not to do so was determined visually, and the offset generation temperature was recorded. The evaluation was performed in a low temperature and low humidity environment (10 ° C./10% RH).

  Further, the fixing rate was measured for the solid black image portion obtained at each temperature. The fixing rate was calculated by measuring the fixing strength by the following mending tape peeling method.

  When the fixing rate is 85% or higher, the fixing ability is evaluated at a temperature at which the fixing rate is 85% or higher because it is a level at which it can be determined that there is no practical problem.

  The evaluation results are shown in “Table 2” below.

(Mending tape peeling method)
1) Measure absolute reflection density D ₀ in a solid black image.
2) Lightly affix the mending tape “No.810-3-12” (manufactured by Sumitomo 3M) to the solid black image.
3) Reciprocating and rubbing on the mending tape 3.5 times with a pressure of 1 kPa.
4) The mending tape is peeled off at an angle of 180 ° C. and a force of 200 g.
5) measuring the absolute reflection density D ₁ of the post-peeling.
6) The fixing rate is calculated based on the following formula (4).

Formula (4); Fixing rate (%) = D ₁ / D ₀ × 100
For the measurement of absolute reflection density, a reflection densitometer “RD-918” (manufactured by Macbeth Co.) was used.

  The evaluation results are shown in “Table 3” below.

(Preservation evaluation)
2 g of each toner was placed in a glass sample bottle (25 ml), left in an environment of 55 ° C./80% RH for 12 hours, then treated with a 100 mesh sieve, and the residual amount on the sieve was measured. Evaluation was based on the residual ratio (%) relative to the initial weight.

  If it is 5% or less, there is no problem in practical use.

  The evaluation results are shown in “Table 4” below.

(Live-action evaluation)
Using a digital copying machine “bizhub PRO 1050” (manufactured by Konica Minolta), using a 5% pixel rate image in a high temperature and high humidity environment (33 ° C./80% RH), and stopping every 10 sheets for 10 seconds Print evaluation of 300,000 sheets in the 10-sheet intermittent mode, solid black image density (reflection density: absolute reflection density) and fog density (reflection density: paper reflection density) from the initial and 300,000 sheets later images The relative reflection density “0” was evaluated.

  The evaluation results are shown in “Table 5” below.

  As can be seen from the results of Tables 1 to 5, Examples 1 to 8 within the present invention may have any characteristics, but Comparative Examples 1 to 3 outside the present invention have problems with at least any of the characteristics. I understand that.

Claims (3)

An electrostatic latent image developing toner comprising at least a resin and a colorant, wherein the resin contains 1 to 20% by mass of a monomer unit represented by the following general formula (1): Toner.

However, n = 2 to 5 integers 2. The toner for developing an electrostatic latent image according to claim 1, wherein the toner is ion-crosslinked with polyvalent metal ions. 3. An image forming method comprising fixing a toner image produced using the electrostatic latent image developing toner according to claim 1 by a contact heating fixing device.