JP2010044369A - Image forming method and image forming apparatus using non-contact heat fixing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and an image forming apparatus, in which an image is fixed by a non-contact heat fixing system and a finished image is excellent in document offset resistance. <P>SOLUTION: The image forming method includes fixing an image formed of a toner containing at least a resin, a colorant and a release agent, by a non-contact heat fixing system, wherein the release agent is ester wax expressed by general formula:R<SB>1</SB>-(OCO-R<SB>2</SB>)<SB>n</SB>(wherein R<SB>1</SB>and R<SB>2</SB>represent hydrocarbon groups and n is 1 to 4). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method and an image forming apparatus using non-contact heat fixing.

  The thermal fixing method used in the electrostatic latent image developing method such as electrophotographic process is a method in which heat roll fixing or the like is brought into pressure contact with a toner image, and heat and pressure are applied to fix by heat conduction. There are two main types: non-contact heat fixing such as oven fixing and heat fixing by heat radiation.

  At present, contact-type heat fixing is widely used for many copying machines and printers using an electrophotographic process because of their high thermal efficiency. However, non-contact heat fixing has become the mainstream in areas where high image quality and high-speed double-sided image formation is required, such as in the field of light printing, which has been increasingly applied in recent years (see, for example, Patent Document 1).

  However, in non-contact fixing, even when the fold fixing property indicating the fixing strength of the image when the finished image is folded is good, the resin in the image area melts particularly when the printed matter is stacked in a high temperature, high humidity and high pressure state. There is a problem of document offset which causes image loss when it is attached to the other paper surface and peeled off.

JP 2006-267215 A

  An object of the present invention is to provide an image forming method and an image forming apparatus which are fixed by a non-contact heat fixing method and have excellent document offset resistance of a finished image.

  As a result of intensive studies by the inventors, it has been found that the object of the present invention can be achieved by adopting the following configuration.

(1)
In an image forming method for fixing an image formed by a toner containing at least a resin, a colorant, and a release agent by non-contact heat fixing, the release agent is an ester wax represented by the following general formula: An image forming method.

R _1- (OCO-R ₂ ) _n (R ₁ and R ₂ are hydrocarbon groups, n = 1 to 4)
(2)
The image forming method according to (1), wherein the ester wax is contained in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the toner.

(3)
The image forming method according to (1) or (2), wherein the toner is produced by aggregating / fusing at least resin fine particles.

(4)
An image forming apparatus, wherein the image forming method according to any one of (1) to (3) is used, and an unfixed toner image is non-contact heat-fixed while being conveyed at 1.5 m / second or more.

  According to the present invention, it is possible to provide an image forming method and an image forming apparatus which are fixed by a non-contact heat fixing method and have excellent document offset resistance of a finished image.

1 is a cross-sectional view showing an example of an image forming apparatus used in an image forming method of the present invention. FIG. 3 is a structural cross-sectional view illustrating an example of a fixing device used in the present invention.

  When fixing by a non-contact heat fixing method as in the present invention, it is possible to fix an unfixed toner image on which an image of 1.5 m / second or more is formed (the upper limit is probably 6.0 m / second). This indicates that it is possible to form an image at a speed of 300 sheets / min.

  In non-contact heat fixing, since the fixing pressure is not applied to the toner layer, a fine image can be output. On the other hand, since the fixing pressure is not applied, the fixing property is disadvantageous as compared with the contact heating fixing, and unevenness is generated on the fixing surface, so that document offset is likely to occur.

  A release agent for preventing toner offset to the heating member in the contact heating fixing is not necessary. Not only that, the release agent has a lower melting point than the toner resin and is interposed on the surface of the toner layer. It has been thought to work to weaken the fixability of toner images. In the case of fixing by a non-contact heat fixing method, it is considered that there is a high possibility of performing a harmful action. In fact, when a normal release agent is used, the document image anti-offset property of the toner image is hardly improved.

  However, when an ester wax is used as a toner release agent as in the present invention, document offset can be prevented contrary to expectations, and the object of the present invention can be achieved. The reason is estimated as follows.

  When fixing a toner image, when the toner is melted by heating, especially ester wax has a sharp melt and low viscosity melting property, and therefore tends to be more oriented on the surface than other release agents in high-speed image formation. The image surface becomes smooth. As a result, when the images are overlapped, the image contact portion is protected by the highly separable wax even under high temperature and high humidity, so that document offset can be prevented.

Ester wax R _1- (OCO-R ₂ ) _n
(R 1, _{R 2} is a hydrocarbon group, n = 1 to 4)
N is preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4.

R ₁ has 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 2 to 5 carbon atoms, and R ₂ has 1 to 40 carbon atoms, preferably 16 to 20 carbon atoms, and more preferably 18 to 26 carbon atoms.

  The addition amount of the ester wax is preferably 1 to 20 parts by mass, particularly preferably 3 to 15 parts by mass with respect to 100 parts by mass of the toner.

  Specific examples include compounds having the following structures.

[Toner Production Method]
As a method for producing the toner of the present invention, a toner production method by an emulsion association method is preferably used. In particular, a toner manufacturing method in which resin particles having a multi-stage polymerization structure formed by emulsion polymerization of miniemulsion polymerized particles is associated (aggregated / fused) is preferable.

Next, an example of a toner production method by the miniemulsion polymerization association method will be described in detail. This toner manufacturing method is manufactured through the following steps.
(1) Dissolution / dispersion step of dissolving or dispersing the release agent in the radically polymerizable monomer (2) The polymerizable monomer solution in which the release agent is dissolved / dispersed is formed into droplets in an aqueous medium to form a mini Polymerization step for preparing a dispersion of resin particles by emulsion polymerization (3) Aggregation and fusion step for associating resin particles in an aqueous medium to obtain associated particles (4) Aging of the associated particles with thermal energy to form the shape A maturing step to prepare toner base particles (5) Cooling step for cooling the dispersion of the toner base (6) Solid-liquid separation of the toner base from the cooled dispersion of the toner base, and a surfactant from the toner base (7) Drying Step for Drying the Washed Toner Base (8) Step for Adding External Additive to Dry Toner Base Each step will be described below.

(1) Dissolution / dispersion step This step is a step of preparing a radical polymerizable monomer solution of the release agent by dissolving or dispersing the release agent in the radical polymerizable monomer.

(2) Polymerization step In a preferred example of this polymerization step, a radical polymerizable monomer solution in which the release agent is dissolved or dispersed is added to an aqueous medium containing a surfactant, and mechanical energy is increased. In addition, droplets are formed, and then the polymerization reaction proceeds in the droplets by radicals from the water-soluble radical polymerization initiator. In addition, you may add the resin particle as a core particle in the said aqueous medium.

  By this polymerization step, resin particles containing a release agent and a binder resin are obtained. Such resin particles may be colored particles or non-colored particles. The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. In addition, when using non-colored resin particles, in the aggregation step described later, the dispersion of the colorant particles is added to the dispersion of the resin particles to aggregate the resin particles and the colorant particles. It can be colored particles.

(3) Aggregation / fusion process The aggregation process is a process of forming colored particles using resin particles (colored or non-colored resin particles) obtained by the polymerization process and, if necessary, colorant particles. In the aggregation step, resin particles and colorant particles can be aggregated together with release agent particles, internal additive particles such as charge control agents, and the like.

  The colorant particles can be prepared by dispersing the colorant in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water. The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gorin or a pressure homogenizer, a sand grinder, a Getzmann mill, a diamond fine mill, or the like. A medium type disperser is mentioned.

  The colorant particles may be surface modified. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is separated by filtration, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  A preferred aggregating method is to add a salting-out agent composed of an alkali metal salt, an alkaline earth metal salt, or the like as an aggregating agent having a critical aggregation concentration or more in water in which resin particles and colorant particles are present, This is a method of agglomerating at or above the glass transition point of the resin particles.

(4) Aging step Aging is preferably performed by thermal energy (heating).

  Specifically, the liquid containing the associated particles is heated and stirred to adjust the shape of the associated particles to the desired circularity by the heating temperature, the stirring speed, and the heating time to obtain toner base particles. is there.

(5) Cooling Step This step is a step of cooling (rapid cooling) the toner base dispersion. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

(6) Washing Step In this solid-liquid separation / washing step, a solid-liquid separation process for solid-liquid separation of the toner base from the dispersion of the toner base that has been cooled to a predetermined temperature in the above step, and a solid-liquid separated toner A cleaning process is performed to remove deposits such as a surfactant and a salting-out agent from the cake (an aggregate obtained by agglomerating the toner base in a wet state into a cake).

  In the washing treatment, the filtrate is washed with water until the electric conductivity of the filtrate reaches 10 μS / cm. Examples of the filtration method include a centrifugal separation method, a vacuum filtration method using Nutsche and the like, and a filtration method using a filter press and the like, and are not particularly limited.

(7) Drying step This step is a step of drying the washed toner cake to obtain a dried toner base. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The water content of the dried colored particles is preferably 5% by mass or less, more preferably 2% by mass or less.

  In addition, when the dried colored particles are aggregated by weak interparticle attractive force, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

(8) External Addition Processing Step This step is a step of preparing a toner by mixing an external additive with the dried toner base as necessary.

  As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

[Binder resin]
When the toner particles constituting the toner of the present invention are produced by a pulverization method, a dissolution suspension method, or the like, a styrene resin, (meth) acrylic resin, styrene- (meta) is used as a binder resin constituting the toner. ) Known vinyl resins such as acrylic copolymer resins and olefin resins, polyester resins, polyamide resins, carbonate resins, polyethers, polyvinyl acetate resins, polysulfones, epoxy resins, polyurethane resins, urea resins, etc. These various resins can be used. These can be used alone or in combination of two or more.

  In addition, when the toner particles constituting the toner of the present invention are produced by a suspension polymerization method, a miniemulsion polymerization aggregation method, an emulsion polymerization aggregation method, or the like, a polymerizable single amount for obtaining each resin constituting the toner For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2, Styrene such as 4-dimethyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, or the like Styrene styrene derivatives; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, methacryl Methacrylic acid such as isopropyl, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate Ester derivatives; methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate , Acrylic ester derivatives such as phenyl acrylate; olefins such as ethylene, propylene, isobutylene; vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride Vinyl halides such as vinylidene fluoride; vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone Vinyl ketones such as N-vinyl carbazole, N-vinyl indole, N-vinyl compounds such as N-vinyl pyrrolidone; vinyl compounds such as vinyl naphthalene and vinyl pyridine; acrylic acid such as acrylonitrile, methacrylonitrile, acrylamide or the like Mention may be made of vinyl monomers such as methacrylic acid derivatives. These vinyl monomers can be used alone or in combination of two or more.

  Moreover, it is preferable to use combining what has an ionic dissociation group as a 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.

[Surfactant]
When the toner particles constituting the toner of the present invention are produced by suspension polymerization, miniemulsion polymerization aggregation or emulsion polymerization aggregation, the surfactant used for obtaining the binder resin is particularly limited. Although not intended, sulfonate (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate), sulfate ester salt (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salt (olein) Suitable examples include ionic surfactants such as sodium oxalate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, and the like. Also, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester, etc. Nonionic surfactants can also be used. These surfactants are used as an emulsifier when a toner is obtained by an emulsion polymerization method, but may be used for other processes or purposes.

(Polymerization initiator)
When the toner particles constituting the toner of the present invention are produced by suspension polymerization, miniemulsion polymerization aggregation or emulsion polymerization aggregation, the binder resin 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.

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

[Chain transfer agent]
A chain generally used for the purpose of adjusting the molecular weight of the binder resin when the toner particles constituting the toner of the present invention are produced by suspension polymerization, miniemulsion polymerization aggregation or emulsion polymerization aggregation. A transfer agent can be 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.

[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.

[Flocculant]
When the toner particles constituting the toner of the present invention are produced by the miniemulsion polymerization aggregation method or the emulsion polymerization aggregation method, examples of the aggregation agent used for obtaining the binder resin include alkali metal salts and alkaline earth metal salts. Can be mentioned. Examples of the alkali metal constituting the flocculant include lithium, potassium, and sodium, and examples of the alkaline earth metal constituting the flocculant include magnesium, calcium, strontium, and barium. Of these, potassium, sodium, magnesium, calcium, and barium are preferable. Examples of the counter ion (anion constituting the salt) of the alkali metal or alkaline earth metal include chloride ion, bromide ion, iodide ion, carbonate ion and sulfate ion.

[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.

[Particle size of toner particles]
The toner of the present invention preferably has a number average particle diameter of 3 to 8 μm. When the toner particles are formed by a polymerization method, the particle size is controlled by the concentration of the aggregating agent, the amount of the organic solvent added, the fusing time, and the composition of the polymer itself in the above-described toner manufacturing method. can do.

  The number average particle size is 3 to 8 μm, so that reproducibility of fine lines and high image quality of photographic images can be achieved, and the amount of toner consumption can be reduced as compared with the case of using a large particle size toner. Can do.

[Average circularity of toner particles]
The toner of the present invention preferably has an average circularity represented by the following formula (3) of 0.930 to 1.000 for the individual toner particles constituting the toner, from the viewpoint of improving transfer efficiency. More preferably, it is 0.950-0.995.

Formula (3): Average circularity = peripheral length of circle obtained from equivalent circle diameter / perimeter length of projected particle image [external additive]
To the toner of the present invention, so-called external additives can be added and used for the purpose of improving fluidity, chargeability and cleaning property. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.

  As the inorganic fine particles, it is preferable to use inorganic oxide particles such as silica, titania and alumina, and these inorganic fine particles are preferably hydrophobized with a silane coupling agent or a titanium coupling agent. . As the organic fine particles, spherical particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As the organic fine particles, polymers such as polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymer can be used.

  The addition ratio of these external additives is a ratio of 0.1 to 5.0% by mass, preferably 0.5 to 4.0% by mass in the toner. In addition, various external additives may be used in combination.

(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 diameter 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 Method and Image Forming Apparatus]
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.

  FIG. 1 is an explanatory diagram showing an example of an image forming apparatus used in an image forming method using toner according to the present invention.

  This image forming apparatus is a tandem color image forming apparatus having a configuration in which four sets of image forming units 100Y, 100M, 100C, and 100Bk are provided along an intermediate belt 14a that is an intermediate transfer member.

  Each of the image forming units 100Y, 100M, 100C, and 100Bk is formed by forming a photoconductive layer made of a conductive layer and an organic photoreceptor (OPC) on the outer peripheral surface of a cylindrical base, and a driving source (not shown) Photoconductor drum 10Y comprising a photoconductor drum 10Y, 10M, 10C, 10Bk that is rotated counterclockwise by the power from the motor or following the intermediate belt 14a and the conductive layer is grounded, and a scorotron charger. Charging that is arranged in a direction orthogonal to the moving direction of 10M, 10C, and 10Bk and that gives a uniform potential to the surfaces of the photosensitive drums 10Y, 10M, 10C, and 10Bk by corona discharge having the same polarity as the toner. The photosensitive drums 10Y, 10M, 10C, and 10B by means 11Y, 11M, 11C, and 11Bk and a polygon mirror, for example. Exposure means 12Y for forming a latent image by performing image exposure on the surface of the uniformly charged photoreceptor drums 10Y, 10M, 10C, and 10Bk by scanning in parallel with the rotation axis of 12M, 12C, 12Bk and rotating developing sleeves 131Y, 131M, 131C, 131Bk, and developing means 13Y, 13M, for conveying the toner held thereon to the surfaces of the photosensitive drums 10Y, 10M, 10C, 10Bk 13C and 13Bk.

  Here, the image forming unit 100Y forms a yellow toner image, the image forming unit 100M forms a magenta toner image, and the image forming unit 100C forms a cyan toner image. According to the image forming unit 100Bk, a black toner image is formed.

  In such an image forming apparatus, the toner images of the respective colors formed on the photoconductive drums 10Y, 10M, 10C, and 10Bk of the image forming units 100Y, 100M, 100C, and 100Bk are transferred at the same timing. A color toner image is formed by sequentially transferring and superimposing on the material P by the transfer means 14Y, 14M, 14C, and 14Bk, and is transferred onto the transfer material P in a batch by the secondary transfer means 14b and separated. 16 is separated from the intermediate belt 14a by the fixing device 17 and fixed by the fixing device 17, and finally discharged from the discharge port 18 to the outside of the apparatus.

[Fixing device]
Examples of the fixing method used in the above image forming method include so-called non-contact heating type fixing devices. For example, FIG. 2 is a cross-sectional view illustrating an example of a configuration of a fixing device in an image forming apparatus in which the toner of the present invention is used.

  The fixing device 17 is surrounded by the partition wall 4, has a slit-shaped recording paper (transfer material) carry-in port 5 and a carry-out port 6, and has a configuration in which the heater 3 is arranged inside. A toner image T formed on the recording paper P is moved by the web 1 for conveying the recording paper moving through the recording paper conveying port 5 and the outlet 6 and heated by the heater 3 arranged in a non-contact state. Is fixed on the recording paper.

  That is, the fixing device used in the present invention is a fixing device that does not transfer heat by conduction by sandwiching a recording paper between a heat roller or a heat belt that has been widely used in the past, but fixes by heat radiated from a heat source. .

  As mentioned above, when contact heating is performed with a heat roller or the like, the transmission efficiency is basically good, but for that purpose, the contact between the heat roller and the recording paper must be maintained securely. If this is not possible, the fixing will be poor. However, if the toner image is to be fixed at an extremely high speed, it is necessary to make the conveyance speed extremely fast, so that it becomes difficult to sandwich the recording paper with a heat roller that is appropriately fixed. On the other hand, if the nip is performed with a hot roller that is too hot, the toner will be offset onto the hot roller.

  On the contrary, in non-contact heating, the heat roller and recording paper are not in contact, so it is possible to convey at high speed and increase the heat source power to give the amount of heat necessary to fix the toner in the meantime. It is. However, since the fixing method is not a method in which the toner is pressed against the recording paper by applying pressure, there arises a problem that the fixing power of the toner image after heat fixing is inevitably weakened.

  Next, the configuration and effects of the present invention will be further described using typical embodiments. However, of course, the configuration of the present invention is not limited to these specific configurations.

Example 1
Production of Colorant Fine Particles 59.0 g of an anionic surfactant was dissolved in 1600 ml of ion-exchanged water with stirring. While this solution was stirred, a colorant was added, and then a dispersion of “SC mill” (manufactured by Mitsui Mining Co., Ltd.) was used to prepare a dispersion of colorant fine particles. The volume average particle diameter of the colorant fine particles in this colorant dispersion was measured using a dynamic light scattering particle size analyzer “Microtrack UPA150” (manufactured by Nikkiso Co., Ltd.), and found to be 150 nm.

Production of multistage resin fine particles First stage polymerization Into a 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction apparatus, 8 g of sodium dodecyl sulfate and 3 L of ion-exchanged water were charged at a stirring speed of 230 rpm under a nitrogen stream. The internal temperature was raised to 80 ° C. while stirring. After raising the temperature, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the solution temperature was again 80 ° C., and after dropwise addition over the following monomer mixture over 1 hour, the mixture was heated at 80 ° C. for 2 hours. Polymerization was performed by stirring to prepare resin particles. This is referred to as “resin particles (1H)”.

Styrene 480g
n-Butyl acrylate 250g
Methacrylic acid 68.0g
n-octyl mercaptan 16.0 g
Second stage polymerization In a 5 L (liter) reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device, a solution of 7 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 800 ml of ion-exchanged water was added. After charging and heating to 98 ° C., 260 g of the resin particles (1H) and a solution obtained by dissolving the following monomer solution at 90 ° C. are added, and a mechanical disperser CLEARMIX (M Technique ( Manufactured by Co., Ltd.) for 1 hour to prepare a dispersion containing emulsified particles (oil droplets).

Styrene 245g
120 g of n-butyl acrylate
n-Octyl mercaptan 1.5g
190 g of ester wax A (melting point 70 ° C.)
(Specific compound example No. 4))
Next, an initiator solution in which 6 g of potassium persulfate is dissolved in 200 ml of ion-exchanged water is added to this dispersion, and the system is heated and stirred at 82 ° C. for 1 hour to obtain resin particles. It was. This is referred to as “resin particles (1HM)”.

Third stage polymerization Furthermore, a solution in which 11 g of potassium persulfate was dissolved in 400 ml of ion-exchanged water was added.
Styrene 435g
n-Butyl acrylate 130g
Methacrylic acid 33g
n-Octyl mercaptan 8g
A monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin particles. This is designated as “resin particle A-1”.

Production of single-layer resin particles B A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device was charged with 2.3 g of sodium dodecyl sulfate and 3 L of ion-exchanged water, and stirred at a rate of 230 rpm under a nitrogen stream The internal temperature was raised to 80 ° C. while stirring. After heating, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the liquid temperature was again 80 ° C., the following monomer mixture was added dropwise over 1 hour, and then heated at 80 ° C. for 2 hours. Polymerization was carried out by stirring to prepare resin particles. This is designated as “resin particle B-1”.

Styrene 520g
210g of n-butyl acrylate
Methacrylic acid 68.0g
n-octyl mercaptan 16.0 g
Aggregation / fusion process 300 g of resin particles A-1 in terms of solid content, 1400 g of ion-exchanged water, “colorant dispersion” 1 ”120 g and a solution of 3 g of polyoxyethylene (2) sodium dodecyl ether sulfate dissolved in 120 ml of ion-exchanged water were prepared, the temperature was adjusted to 30 ° C., and 5N sodium hydroxide aqueous solution was added to adjust the pH. Adjusted to 10. 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. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 90 ° C.

  In this state, the particle size of the associated particles was measured with “Coulter Multisizer 3”, and when the median diameter on the volume basis became 3.1 μm, 45 g of resin particles B-1 were added in terms of solid content, Furthermore, the particle growth reaction was continued. 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 stop particle growth, and further by heating and stirring at a liquid temperature of 90 ° C. as a fusion process, Fusion between particles was allowed to proceed until the circularity was 0.965 as measured by FPIA-2100. Thereafter, the solution was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

Washing / Drying Step Solid-liquid separation was performed with a particle separator “MARK III Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) generated in the aggregation / fusion step to form a wet cake of toner base particles. The wet cake was washed with ion exchange water at 45 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the basket-type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner base particles were prepared by drying until the amount became 0.5% by mass.

Preparation of Toner Particles To the toner base particles obtained above, 1.2% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.6% of hydrophobic titania (number average primary particle size = 20 nm). % And 1.0% by mass of abrasive fine particles were added and mixed with a Henschel mixer to prepare a toner.

[Performance evaluation]
(Document offset)
In document offset evaluation, the fixed image is overlapped so that the image portion, the non-image portion, and the image portion overlap each other, and a weight is placed on the overlapped portion so as to correspond to 80 g / cm ² , and the humidity at 60 ° C. is 50% For 3 days in a constant temperature and humidity chamber. After being allowed to stand, image defects of the two superimposed fixed images were evaluated according to the following criteria. The evaluation results are shown in the table.

  (Double-circle): There is no problem at all because there is no image defect due to toner transfer and slight sticking between images.

  ○: A zipping sound is heard when separating the superimposed images, but there is no image defect and no problem.

Δ: When separating the superimposed images, gloss unevenness occurs in both images, but there is almost no defect as an image. ×: Transfer to a non-image part, peeling due to transfer between contact images, etc. are recognized. It cannot be used practically.

(Fixability)
The fixed image was folded using a folding machine, and 0.35 MPa of air was blown onto the fixed image. Evaluation was made in five stages with reference to the limit sample of the fold.

Rank 5: No peeling at the fold Rank 4: Partial peeling according to the fold Rank 3: Thin linear peeling according to the fold Rank 2: Thick linear peeling according to the fold Rank 1: Large peeling on the image The results are shown in the table.

  Thereafter, wax was added as shown in the following table in the same procedure as in Example 1 to prepare a toner, and evaluation was performed in the same manner as in Example 1.

  The results are shown in Table 1 together with Example 1.

Ester wax A: Specific compound example No. 4)
Ester wax B: Specific compound example No. 13)
Ester wax C: Specific compound example No. 17)
Examples 1 to 8 within the present invention may have any characteristics, but Comparative Examples 1 to 18 outside the present invention have at least any problems.

DESCRIPTION OF SYMBOLS 1 Web 3 Heater 4 Bulkhead 5 Carrying-in port 6 Carrying-out port 10Y, 10M, 10C, 10Bk Photosensitive drum 11Y, 11M, 11C, 11Bk Charging means 12Y, 12M, 12C, 12Bk Exposure means 13Y, 13M, 13C, 13Bk Developing means 131Y , 131M, 131C, 131Bk Developing sleeve 14a Intermediate belt 14Y, 14M, 14C, 14Bk Transfer means 14b Secondary transfer means 16 Separating means 17 Fixing device 18 Discharge port 100Y, 100M, 100C, 100Bk Image forming unit T Toner image P Transfer material (Recording paper)

Claims (4)

In an image forming method for fixing an image formed by a toner containing at least a resin, a colorant, and a release agent by non-contact heat fixing, the release agent is an ester wax represented by the following general formula: An image forming method.
R _1- (OCO-R ₂ ) _n (R ₁ and R ₂ are hydrocarbon groups, n = 1 to 4) The image forming method according to claim 1, wherein the ester wax is contained in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the toner. 3. The image forming method according to claim 1, wherein the toner is produced by agglomerating / fusing at least resin fine particles. An image forming apparatus using the image forming method according to any one of claims 1 to 3, wherein the non-fixed toner image is fixed by heating while being conveyed at a speed of 1.5 m / sec or more.

Images