JP2005274617A - Electrophotographic toner, production method therefor and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic toner which realizes excellent thermal fixation of image and provides a satisfactory image quality in an image forming apparatus provided with a fixing member having a high surface energy, and also to provide a production method for the electrophotographic toner and an image forming method using the electrophotographic toner. <P>SOLUTION: The electrophotographic toner is used for the image forming apparatus provided with a fixing member having a surface energy of ≥5.0×10<SP>-2</SP>J/m<SP>2</SP>and contains at least binder resin, a colorant and a releasing agent, wherein the content of the releasing agent is 10 to 40 mass.% and styrene-diene copolymer resin of 5 to 50 mass.% is contained in the binder resin. The production method for the electrophotographic toner and the image forming method using the electrophotographic toner are disclosed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic toner used for developing an electrostatic latent image formed in an electrophotographic process and the like, a method for producing the same, and an image forming method using the electrophotographic toner.

  A number of methods are known as electrophotographic methods, as described in Patent Documents 1 and 2 and the like. In general, an exposure process for forming an electrical latent image using various means on a photosensitive layer using a photoconductive substance, a development process using toner, a process for transferring toner to a recording material such as paper, The process consists of basic processes such as a process of fixing a toner image on a recording material by heating, pressure, thermal pressure or solvent vapor, and a process of removing toner remaining on the photoreceptor layer.

Recently, there has been an increasing demand for a copying machine or printer that uses electrophotography to be inexpensive and small, but in designing such a copying machine or printer, how to fix toner with low power consumption. At the same time, it is important to simplify the fixing method.
Currently, a fixing method using a heat roll is most commonly used as a means for fusing and fixing toner on paper. As the thermal roll, in order to prevent the toner from fusing to the roll when the toner is fixed by heat, the roll surface layer is coated with a material having a small surface energy such as a fluororesin, and the roll surface material is limited. It had been.

  When the fixing roll is heated, these fluororesins may inhibit heat conduction, and the thickness of the fluororesin on the surface layer of the fixing roll is limited in order to efficiently conduct heat. In addition, these resins can be worn or damaged by repeated use, so that the wettability of the fixing roll surface cannot be stably maintained for a long period of time. Therefore, development of a toner that does not require coating the surface of the fixing roll with a fluorine-based resin or the like is desired.

On the other hand, in the pressure fixing method, an example using a metal roll is known (for example, see Patent Document 3). However, the pressure fixing has a problem that the fixing property of the fixed image is weak because it is pressed by pressure, and can be easily peeled off by an external force such as a ballpoint pen.
In order to improve the fixing property by the pressure fixing method, a microcapsule toner having a microphase separation structure composed of a continuous phase of a resin and a high boiling point solvent (for example, see Patent Document 4) has been tried. Therefore, there were problems in storage stability and fixed image blocking properties.

Further, as an oilless fixing method that does not require oil supply to the heat roll, a method of adding a release agent such as wax to the toner (see, for example, Patent Document 5), and a release agent along the toner surface A method of disposing a release agent layer (for example, see Patent Document 6) and a toner using a styrene-diene copolymer such as styrene-butadiene as a resin (for example, see Patent Document 7) are also known. In any case, it was necessary to use a heat-fixing roll having a small surface energy as described above in order to obtain releasability. For this reason, the durability and thermal conductivity of the fixing roll are reduced and it is difficult to obtain a stable and stable image.
US Patent 2,297,691 Japanese Patent Publication No.42-23910 JP 51-36947 A JP-A-6-19182 JP-A-61-62045 JP 11-327201 A JP-A-8-181740

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention provides an image forming apparatus including a fixing member having a high surface energy, which enables satisfactory thermal fixing of an image and obtains good image quality, a method for producing the same, It is an object of the present invention to provide an image forming method using the electrophotographic toner.

As a result of intensive studies to solve the above problems, the present inventors have found that the following problems can be solved by the present invention.
That is, the present invention is used in an image forming apparatus including a fixing member having a surface energy of 5.0 × 10 ⁻² J / m ² or more, and includes at least a binder resin, a colorant, and a release agent. An electrophotographic toner comprising:
The content of the release agent is 10 to 40% by mass,
The toner for electrophotography, wherein the binder resin contains 5 to 50% by mass of a styrene-diene copolymer resin.

The electrophotographic toner of the present invention preferably comprises at least one or more of the following first and second aspects.
(1) In the first aspect, the content of the release agent on the toner surface is 3% or less, and the distance R in the region from the center to 1 / 3R of the distance R from the center of the toner to the toner surface. The embodiment is characterized in that the content of the dosage form is 10% or less.
(2) In the second embodiment, at least one external additive is contained, the number average particle diameter of the external additive is 0.02 to 1.0 μm, and the thermal conductivity at 300 K is 40 to 40. It is an aspect characterized by being 500 W / mK.

  The present invention also provides a resin fine particle dispersion (1) containing at least first resin fine particles containing a styrene-diene copolymer, a colorant dispersion containing a colorant, and a release agent containing a release agent. A resin fine particle dispersion liquid (2) containing second resin fine particles is further added to the core aggregate particles obtained by mixing and aggregating with the dispersion liquid, and a shell containing the second resin fine particles on the surface of the core aggregate particles. An electrophotographic toner manufacturing method is characterized in that a layer is formed to form core / shell agglomerated particles, which are heated at a temperature higher than the glass transition point of resin fine particles, and fused and coalesced.

The present invention further includes a charging step for charging the surface of the image carrier, an electrostatic latent image forming step for forming an electrostatic latent image according to image information on the charged surface of the image carrier, and the electrostatic latent image. A development step of developing the image with toner to obtain a toner image, a transfer step of transferring the toner image to the surface of the recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium by heating. An image forming method comprising:
The surface energy of the fixing member used in the fixing step is 5.0 × 10 ⁻² J / m ² or more,
The toner includes at least a binder resin, a colorant, and a release agent;
The content of the release agent is 10 to 40% by mass,
In the image forming method, 5 to 50% by mass of a styrene-diene copolymer resin is contained in the binder resin.

  According to the present invention, in an image forming apparatus including a fixing member having a high surface energy, an electrophotographic toner capable of achieving good thermal fixing of an image and obtaining good image quality, a method for producing the same, and An image forming method can be provided.

  Hereinafter, the electrophotographic toner of the present invention, the production method thereof, and the electrophotographic toner will be described in detail.

<Toner for electrophotography>
The electrophotographic toner of the present invention is used in an image forming apparatus including a fixing member having a surface energy (20 ° C.) of 5.0 × 10 ⁻² J / m ² or more.
The surface of a fixing member such as a fixing roll is covered with a low surface energy member such as a fluorine-based resin in order to prevent toner from fusing to the member. However, there is a problem that it is difficult to maintain the wettability of the surface stably for a long period of time due to wear or damage by repeated use. Therefore, in the present invention, the surface energy of the fixing member of the image forming apparatus using the electrophotographic toner is set to 5.0 × 10 ⁻² J / m ² or more. When the surface energy is less than 5.0 × 10 ⁻² J / m ² , it is impossible to stably maintain the surface wettability described above for a long period of time. The surface energy is preferably 5.0 × 10 ^{−2 to} 10 J / m ² .
Examples of the image forming apparatus provided with the fixing member include a copying machine, a fax machine, and a laser printer.

In the present invention, the heat fixing member that is conventionally coated with a low surface energy film such as a fluorine resin film is not used. As the fixing member having a surface energy (20 ° C.) of 5.0 × 10 ⁻² J / m ² or more, for example, a SUS material or an Al material that is a core metal material of a general fixing member may be exposed as it is. . Considering practicality and the like, the surface energy (20 ° C.) is preferably 0.1 to 5 J / m ² .

  The fixing member is not particularly limited, but a fixing member having high durability and high thermal conductivity is desirable. Specifically, metals such as Fe, Cr, Cu, Ni, Co, Mn, and Al, and materials obtained by mixing these oxides alone or in combination are exemplified. By using such a material for the surface of the fixing member, durability such as strength and wear resistance of the member is improved and thermal conductivity is good, so that thermal efficiency is also improved.

The electrophotographic toner of the present invention (hereinafter sometimes simply referred to as “toner”) contains a binder resin, a colorant, and a release agent. The binder resin contains 5 to 50% by mass of a styrene-diene copolymer resin.
If it is less than 5% by mass, the releasability of the toner is lowered, and if it exceeds 50% by mass, the image fixability is lowered. The styrene-diene copolymer resin is preferably 10 to 40% by mass.

The styrene-diene copolymer is not particularly limited, but is a copolymer of a styrene derivative and a diene derivative such as butadiene or isoprene, and has a copolymerization ratio (styrene-diene copolymer: diene derivative). 95: 5 to 20:80 is preferable, and 90:10 to 50:50 is more preferable.
When the ratio of the styrene derivative is large, the peelability from a fixing member such as a roll may be lowered, and when it is too small, the fixability to paper may be lowered.

In addition to the styrene-diene copolymer, known resin materials can be used. For example, styrenes, methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, lauryl acrylate, ethyl hexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, propyl methacrylate, lauryl methacrylate, methacryl Esters having vinyl groups such as ethyl hexyl acid, vinyl acetate, vinyl benzoate, carboxylic acids having a double bond such as methyl maleate, ethyl maleate, butyl maleate; and the like; acrylic acid, methacrylic acid, maleic acid, etc. Carboxylic acids having a heavy bond; these can be polymerized alone, or two or more can be copolymerized or mixed; and further, epoxy resins, melamine resins, polyester resins, polyurethane resins, polyamide resins , And the like cellulose resin.
Of these, styrene alone, copolymers with acrylic acid esters and methacrylic acid esters, and polyester resins are preferred.

As the colorant, known organic or inorganic pigments and dyes and oil-soluble dyes can be used.
For example, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3, Lamp Black (C.I.No. 77266), Rose Bengal (C.I.No. 45432), Carbon Black, Nigrosine Dye (C.I.No. 50415B), Metal Complex Dye, Metal Examples thereof include derivatives of complex salt dyes and mixtures thereof.
Furthermore, there are various metal oxides such as silica, aluminum oxide, magnetite and various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, and magnesium oxide, and appropriate mixtures thereof. Can be mentioned.

  These colorants are preferably contained in the toner in a proportion of 1 to 50% by mass, depending on the toner particle size and the development amount. In particular, 2 to 25% by mass is preferable. These colorants are dispersed by a known method. For example, a rotary shear type homogenizer, a media type ball mill, a sand mill, or the like is used.

Specific examples of the release agent include the following.
Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax, rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, and petrolatum. Such as petroleum wax. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, and chlorinated hydrocarbon, esters, Synthetic waxes such as ketones and ethers can also be used.
Furthermore, other mold release agents include homopolymers or copolymers of polyacrylates such as poly-n-stearyl methacrylate and poly-n-lauryl methacrylate (for example, n-stearyl acrylate / ethyl methacrylate copolymer) And the like, and crystalline polymers having a long alkyl group in the side chain. Among these, more preferable are petroleum waxes such as paraffin wax and microcrystalline wax, and synthetic waxes.

The content of the release agent in the toner is 10 to 40% by mass. If the content of the release agent is less than 10% by mass, sufficient releasability cannot be ensured and hot offset occurs. On the other hand, when it exceeds 40% by mass, the exposure of the release agent to the toner surface increases, and fluidity and chargeability are impaired.
The content of the release agent is preferably 10 to 30% by mass, and more preferably 15 to 25% by mass.

  In the present invention, among the release agents as exemplified above, it is preferable to use a release agent having a melting point of 50 to 150 ° C, more preferably 50 to 120 ° C, and 60 to 90 ° C. Particularly preferred. If the melting point is 50 ° C. or higher, the toner is excellent in storage stability, and if the melting point is 150 ° C. or lower, the occurrence of hot offset during fixing can be prevented.

The content of the release agent on the toner surface is 3% or less, and the content of the release agent in the region from the center to 1 / 3R of the distance R from the center of the toner to the toner surface is 10% or less. Preferably there is.
By setting the content of the release agent on the toner surface to 3% or less, the chargeability and storage stability of the toner can be improved.
Further, by setting the content of the release agent in the region from the center to 1 / 3R to 10% or less, the ratio of the release agent amount to the toner central portion is reduced, so that the surface of the release agent on the surface of the release agent is reduced. Exposure is promoted, and the peelability at the time of fixing can be improved.
The content of the release agent on the toner surface is more preferably 1% or less. Further, the content of the release agent in the region from the center to 1 / 3R is more preferably 5% by mass.

The content of the release agent on the toner surface can be determined from, for example, the ratio of C and O elements in the release agent and the resin alone and the ratio of C and O in the toner by XPS.
The content of the release agent in the region from the center to 1 / 3R is, for example, the area of the region from the center to 1 / 3R and the area occupied by the release agent in the region, based on the cross-sectional view of the TEM. Can be determined from these values.
In order to control the distribution of the release agent as described above, the method for producing an electrophotographic toner of the present invention described later may be applied.

The electrophotographic toner of the present invention preferably contains external additives such as fine particles, inorganic particles, and organic particles as necessary.
Examples of the fine particles include fine particles such as copper, nickel, silver, aluminum, and zinc oxide. The thermal conductivity of these fine particles is preferably 20 to 500 W / mK at 300K. By setting it as the said range, heat conductivity can be kept favorable and fixability can be improved. More preferably, it is 90-500 W / mK.
The number average particle diameter of the fine particles is preferably 0.02 to 1.0 μm. By setting it as such a range, the peelability at the time of fixing can be made good. A more preferred number average particle diameter is 0.1 to 0.8 μm.
The content of the fine particles in the toner is preferably 0.5% by mass to 20% by mass, and more preferably 1-10% by mass.

Examples of the inorganic particles include all particles used as an external additive on the normal toner surface, such as silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate, and cerium oxide. .
Examples of the organic particles include all particles used as an external additive on the normal toner surface such as vinyl resin, polyester resin, and silicone resin. These inorganic particles and organic particles can be used as fluidity aids, cleaning aids, and the like. When adding inorganic particles or organic particles, the content in the toner is preferably 10% by mass or less, and more preferably 1 to 5% by mass.

  If necessary, a lubricant or a charge control agent may be added to the toner. Examples of the lubricant that can be used include fatty acid amides such as ethylene bisstearylamide and oleic acid amide, and fatty acid metal salts such as zinc stearate and calcium stearate. Examples of the charge control agent include metal salts of benzoic acid, metal salts of salicylic acid, metal salts of alkyl salicylic acid, metal salts of catechol, metal-containing bisazo dyes, tetraphenylborate derivatives, and the like used in powder toners. A compound selected from the group consisting of a quaternary ammonium salt and an alkylpyridinium salt, and a combination thereof can be preferably used. The amount of these external additives added to the toner is generally preferably 10% by mass or less, and more preferably in the range of 0.5 to 8% by mass.

  As for the volume average particle diameter of the toner of the present invention, the volume average particle diameter D50 measured with a Coulter counter is preferably 4.0 to 10.0 μm. More preferably, it is 5.0-8.0 micrometers, Most preferably, it is 5.0-7.5 micrometers. If the thickness is 4.0 μm or more, it is possible to prevent the occurrence of cloud due to toner behavior. On the other hand, if it is 10.0 μm or less, a good quality image can be obtained.

  The particle size distribution of the toner of the present invention is the ratio D84v / D16v (GSDv: volume average particle size distribution index) of the cumulative 84% diameter (D84v) and the cumulative 16% diameter (D16v) of the volume particle diameter measured with a Coulter counter. It is preferable that D84f / D16f (GSDf: number average particle size distribution index) of the number particle diameter is 1.35 or less and 1.50 or less. If GSDv is 1.35 or less and GSDf is 1.50 or less, a good image can be obtained.

<Method for producing electrophotographic toner>
Examples of the toner production method include kneading and pulverization methods, suspension polymerization methods, aggregation coalescence methods, and dissolution suspension methods, and the like. From the viewpoint of controlling the distribution, the suspension polymerization method, the aggregation coalescence method, and the dissolution suspension method are preferable. The method for producing the electrophotographic toner of the present invention will be described below.

  First, a resin fine particle dispersion (1) containing first resin fine particles containing at least a styrene-diene copolymer, a colorant dispersion containing a colorant, and a release agent dispersion containing a release agent. Core agglomerated particles mixed and agglomerated are produced. Thereafter, a resin fine particle dispersion (2) containing second resin fine particles is further added to the prepared core aggregated particles, and a shell layer containing the second resin fine particles is formed on the surface of the core aggregated particles, Form core / shell agglomerated particles. After the formation, they are heated at a temperature higher than the glass transition point of the resin fine particles (resin of the shell layer) to fuse and unite. Thereafter, known treatments such as washing and drying are appropriately performed to produce the toner of the present invention.

In the above production method, after the core aggregated particles are prepared without mixing the release agent dispersion, the release agent dispersion is mixed to form an intermediate layer on the core aggregated particles, and the resin fine particle dispersion ( 2), a shell layer containing the second resin fine particles may be formed on the surface of the core aggregated particles to form three-layered aggregated particles, which may be manufactured through fusion, coalescence, and the like.
By this method, the content of the release agent on the toner surface is set to 5% by mass or less, and the content of the release agent in the region from the center to 1 / 3R in the distance R from the toner center to the toner surface is 10%. It can be made into the mass% or less.

As the styrene-diene copolymer resin, the above-described polymer resins can be used. The binder resin component other than the styrene-diene copolymer resin is also as described above. If the second resin fine particles contained in the resin fine particle dispersion (2) are resins other than the styrene-diene copolymer, the binder resin component described above is used.
As the resin fine particle dispersion, for example, a resin fine particle dispersion in which resin particles are dispersed with an ionic surfactant can be used.
The external addition method in the case of adding an external additive is not particularly limited. For example, the external additive can be added by mixing using a Henschel mixer or the like.

The resin particle diameter of the resin particle dispersion used in the emulsion polymerization aggregation method is preferably 1 μm or less in order to improve the internal dispersibility of the colorant and release agent. More preferably, it is 0.5 μm or less.
The colorant dispersion diameter of the colorant dispersion is preferably 0.5 μm or less from the viewpoint of color development and OHP permeability. More preferably, it is 0.3 μm or less. Moreover, 0.05 micrometer or more is preferable from the point which produces an aggregated particle efficiently.
The release agent dispersion diameter of the release agent dispersion is preferably 0.5 μm or less from the viewpoint of color development and OHP permeability. More preferably, it is 0.3 μm or less. On the other hand, 0.05 μm or more is preferable from the viewpoint of efficiently producing aggregated particles.

  The toner of the present invention can be used as a developer by appropriately combining with a known carrier. The developer becomes a one-component electrostatic latent image developer when the toner of the present invention is used alone, and becomes a two-component electrostatic latent image developer when used in combination with a carrier.

  For example, when a carrier is used, the carrier is not particularly limited, and examples thereof include known carriers. Examples thereof include known carriers such as resin-coated carriers described in JP-A Nos. 62-39879 and 56-11461.

  Specific examples of the carrier include the following resin-coated carriers. Examples of the carrier core particles include normal iron powder, ferrite, and magnetite molding, and the average particle diameter is in the range of about 30 to 200 μm. The average particle diameter can be measured with a Coulter counter after being dispersed in water together with a surfactant, as in the case of toner.

  Examples of the coating resin of the resin-coated carrier include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, and 2-ethylhexyl acrylate. Α-methylene fatty acid monocarboxylic acids such as methyl methacrylate, n-propyl methacrylate, lauryl methacrylate and 2-ethylhexyl methacrylate; nitrogen-containing acrylics such as dimethylaminoethyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile Vinyl pyridines such as 2-vinyl pyridine and 4-vinyl pyridine; vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone Homopolymers such as vinyl ketones such as ethylene; olefins such as ethylene and propylene; vinyl-based fluorine-containing monomers such as vinylidene fluoride, tetrafluoroethylene and hexafluoroethylene; and copolymers comprising two or more types of monomers, Furthermore, silicone resins including methylsilicone, methylphenylsilicone, etc., polyesters containing bisphenol, glycol, etc., epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, polycarbonate resins and the like can be mentioned.

These resins may be used alone or in combination of two or more. The coating amount of the coating resin is preferably in the range of about 0.1 to 10 parts by mass, more preferably in the range of 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the core particles.
For the production of the carrier, a heating kneader, a heating Henschel mixer, a UM mixer, or the like can be used. Depending on the amount of the coating resin, a heating fluidized rolling bed, a heating kiln, or the like can be used. .
The mixing ratio of the toner of the present invention and the carrier in the developer is not particularly limited and can be appropriately selected depending on the purpose.

<Image forming method>
Next, an image forming method using the toner of the present invention will be described.
The image forming method of the present invention comprises a charging step for charging the surface of the image carrier, an electrostatic latent image forming step for forming an electrostatic latent image in accordance with image information on the charged surface of the image carrier, and the static A developing step of developing the electrostatic latent image with toner to obtain a toner image, a transferring step of transferring the toner image onto the surface of the recording medium, and a fixing step of fixing the toner image transferred onto the surface of the recording medium by heating. ,including.
In addition, the surface energy of the fixing member used in the fixing step is 5.0 × 10 ⁻² J / m ² or more.
The toner to be used contains at least a binder resin, a colorant, and a release agent. The content of the release agent is 10 to 40% by mass, and 5 to 50% by mass of styrene in the binder resin. -Diene copolymer resin is contained. Specifically, the above-described electrophotographic toner of the present invention is used.

Since the image forming method of the present invention uses the toner of the present invention that is extremely excellent in releasability at the time of fixing, it is excellent in releasability from a member in contact with the toner image at the time of fixing, and is obtained after hot offset and fixing. It is possible to prevent the occurrence of problems such as a reduction in image quality of the received image.
The image forming method of the present invention is not particularly limited as long as it includes at least the charging step, the electrostatic latent image forming step, the developing step, the transfer step, and the fixing step as described above. Other steps may be included.

  In the charging process and latent image forming process, the surface of the latent image carrier is uniformly charged by a charging means, and then exposed to the latent image carrier using a laser optical system or an LED array to form an electrostatic latent image. It is a process to do. Examples of the charging means include a non-contact charger such as corotron and scorotron, and a contact method in which a latent image carrier surface is charged by applying a voltage to a conductive member in contact with the latent image carrier surface. Any type of charger may be used. However, a contact charging type charger is preferable from the viewpoint that the amount of ozone generated is small, environmentally friendly, and excellent printing durability. In the contact charging type charger, the shape of the conductive member may be any of a brush shape, a blade shape, a pin electrode shape, a roller shape, and the like, but a roller-like member is preferable.

  The developing step refers to the electrostatic latent image on the surface of the latent image carrier by bringing the developer carrier on which the developer layer containing at least the toner of the present invention is formed on the surface of the latent image carrier. In this step, toner particles are adhered to the surface of the latent image carrier to form a toner image (development image). The development method can be performed using a known method, but examples of the development method using a two-component developer include a cascade method and a magnetic brush method.

The transfer process is a process in which the toner image formed on the surface of the latent image carrier is directly transferred to the transfer medium, or the image once transferred to the intermediate transfer body is transferred again to the transfer medium to form a transfer image.
A corotron can be used as a transfer device for transferring the toner image from the latent image carrier to paper or the like. The corotron is effective as a means for uniformly charging the paper, but in order to give a predetermined charge to the paper as a transfer medium, a high voltage of several kV must be applied and a high voltage power source is required. Further, since ozone is generated by corona discharge, the rubber parts and the latent image carrier are deteriorated. Therefore, a conductive transfer roll made of an elastic material is pressed against the latent image carrier to transfer the toner image onto the paper. A contact transfer method is preferred.

The fixing step is a step of fixing the developed image (toner image) transferred on the transfer medium surface by a fixing device. As the fixing device, an oilless heat fixing device using a heat roll is preferably used. The heat fixing device includes a heater lamp for heating inside a cylindrical metal core, and its outer peripheral surface is made of a material having a high surface energy as described above.
The fixing process of an unfixed toner image is performed by inserting a transfer medium on which an unfixed toner image is formed between a fixing roller and a pressure roller or a pressure belt, so that a binder resin, an additive, etc. Fix by heat melting.

  In the case where a cleaning process is provided, the cleaning process is a process in which a blade, a brush, a roll, or the like is brought into direct contact with the surface of the latent image carrier to remove toner, paper dust, dust, etc. adhering to the surface of the latent image carrier. It is.

  In the image forming method of the present invention, when producing a full-color image, each of the plurality of latent image carriers has a developer carrier of each color, and the plurality of latent image carriers and developer carriers. Each color toner image is sequentially laminated on the same transfer medium surface by a series of processes consisting of a latent image forming process, a developing process, a transferring process, and a cleaning process, and the stacked full-color toner images. An image forming method is preferably used in which the toner is thermally fixed in the fixing step. By using the toner or developer in the image forming method, stable development, transfer, and fixing performance can be obtained even in a tandem system suitable for, for example, miniaturization and high-speed color.

  Examples of the transfer medium for transferring the toner image include plain paper, an OHP sheet, and the like used in electrophotographic copying machines, printers, and the like. In order to further improve the smoothness of the image surface after fixing, the surface of the transfer medium is preferably as smooth as possible. For example, coated paper in which the surface of plain paper is coated with resin, art paper for printing, etc. Can be preferably used.

  The following description will be given with reference to examples and comparative examples. However, the present invention is not limited to the following examples and comparative examples.

  In preparing the toners used in Examples 1 to 5 and Comparative Examples 1 and 2, the following samples were prepared.

[Preparation of Resin Particle Dispersion A as Resin Fine Particle Dispersion (1)]
"Styrene-butadiene copolymer resin (styrene / butadiene = 75/25)" ... 120 parts by mass "Anionic surfactant Newlex R (manufactured by NOF Corporation)" ... 6 parts by weight "ion-exchanged water" ..220 parts by mass

The above components are mixed and pre-dispersed for 10 minutes with a homogenizer (Ultra Turrax: manufactured by IKA), and then dispersed for 15 minutes at a pressure of 245 mPa using an optimizer (anti-collision type wet pulverizer: manufactured by Sugino Machine). A resin particle dispersion A having a center diameter of 280 nm was obtained.
The resin particle diameter (center diameter) of the obtained resin particle dispersion was measured with a laser diffraction particle size distribution measuring device (LA-700, manufactured by Horiba, Ltd.) (the same applies to the colorant particles and the release agent particles). .

[Preparation of Resin Particle Dispersion B which is Resin Fine Particle Dispersion (1)]
“Styrene-isoprene copolymer resin (styrene / isoprene = 60/40)” 120 parts by mass “Anionic surfactant Dow Fax (Dow Chemical Co.)” 5 parts by mass “ion-exchanged water”・ 220 parts by mass

  The above components are mixed and pre-dispersed for 10 minutes with a homogenizer (Ultra Turrax: manufactured by IKA), and then dispersed for 15 minutes at a pressure of 230 mPa using an optimizer (anti-collision type wet pulverizer: manufactured by Sugino Machine). A resin particle dispersion B having a center diameter of 250 nm was obtained.

[Preparation of Resin Particle Dispersion C as Resin Fine Particle Dispersion (1)]
"Styrene-butadiene copolymer resin (styrene / butadiene = 90/10)" ... 120 parts by mass "Anionic surfactant Newlex R (manufactured by NOF Corporation)" ... 6 parts by weight "ion-exchanged water"・ 220 parts by mass

  After mixing the above components and pre-dispersing for 10 minutes with a homogenizer (Ultra Turrax: made by IKA), dispersion processing is performed for 15 minutes at a pressure of 250 mPa using an optimizer (anti-collision type wet crusher: made by Sugino Machine). A resin particle dispersion C having a central diameter of 275 nm was obtained.

[Preparation of resin particle dispersion D which is resin fine particle dispersion (2)]
"Styrene (made by Wako Pure Chemical Industries)" ... 300 parts by mass "n-butyl acrylate (made by Wako Pure Chemical Industries)" ... 90 parts by mass "β-carboxyethyl acrylate (made by Rhodia Nikka)" ... 12 Mass part "1,10-decanediol diacrylate (manufactured by Shin-Nakamura Chemical)" ... 6.3 parts by mass "Dodecanethiol (manufactured by Wako Pure Chemical Industries)" ... 21.4 parts by mass

  A solution prepared by mixing 4 parts by weight of the anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.) in 570 parts by weight of ion-exchanged water is added to the mixture of the above components and dispersed, emulsified in a flask, and slowly stirred for 10 minutes. While stirring and mixing, 50 parts by mass of ion-exchanged water in which 6 parts by mass of ammonium persulfate was dissolved was added. Then, after sufficiently replacing the nitrogen in the flask, the solution in the flask was stirred with an oil bath. It heated until it became 70 degreeC, and emulsion polymerization was continued as it was for 5 hours, and the anionic resin particle dispersion D was obtained. The center particle diameter of the resin fine particles in the resin particle dispersion D was 240 nm, the solid content was 41.6%, and the weight average molecular weight Mw was 36500.

[Preparation of Colorant Particle Dispersion A]
"Carbon black R660R (manufactured by Cabot)" ... 30 parts by mass "Anionic surfactant Newrex R (manufactured by Nippon Oil &Fats)" ... 2 parts by mass "ion-exchanged water" ... 220 parts by mass

  The above components are mixed and pre-dispersed for 10 minutes with a homogenizer (Ultra Turrax: manufactured by IKA), and then dispersed for 15 minutes at a pressure of 240 mPa using an optimizer (anti-collision type wet pulverizer: manufactured by Sugino Machine). A colorant particle dispersion A having a center diameter of 340 nm was obtained.

[Preparation of Colorant Particle Dispersion B]
"Copper phthalocyanine B15: 3 (manufactured by Dainichi Seika)" ... 45 parts by mass "Cationic surfactant Neogen RK (Daiichi Kogyo Seiyaku)" ... 5 parts by mass "ion-exchanged water" ... 200 Parts by mass

  After mixing the above components and pre-dispersing for 10 minutes with a homogenizer (Ultra Turrax: made by IKA), dispersion processing is performed for 15 minutes at a pressure of 250 mPa using an optimizer (anti-collision type wet pulverizer: made by Sugino Machine). A colorant particle dispersion B having a center diameter of 375 nm was obtained.

[Preparation of Colorant Particle Dispersion C]
"Magenta pigment R122 (manufactured by Dainichi Seika)" ... 45 parts by mass "Nonionic surfactant Nonipol 400 (manufactured by Sanyo Chemical Co., Ltd.)" ... 5 parts by mass "ion-exchanged water" ... 200 parts by mass

  After mixing the above components and pre-dispersing for 10 minutes with a homogenizer (Ultra Turrax: made by IKA), dispersion processing is performed for 15 minutes at a pressure of 250 mPa using an optimizer (anti-collision type wet pulverizer: made by Sugino Machine). A colorant particle dispersion C having a central diameter of 240 nm was obtained.

[Preparation of Colorant Particle Dispersion D]
"Yellow pigment PY74 (manufactured by Clariant)" ... 45 parts by mass "Nonionic surfactant Nonipol 400 (manufactured by Sanyo Chemical)" ... 5 parts by mass "ion-exchanged water" ... 200 parts by mass

  The above components are mixed and pre-dispersed for 10 minutes with a homogenizer (Ultra Turrax: manufactured by IKA), and then dispersed for 15 minutes at a pressure of 240 mPa using an optimizer (anti-collision type wet pulverizer: manufactured by Sugino Machine). A colorant particle dispersion D having a central diameter of 220 nm was obtained.

[Preparation of release agent particle dispersion A]
“Polyethylene wax PW725 (melting point 104 ° C .: manufactured by Toyo Petrolite)” 45 parts by mass “Cationic surfactant Neogen RK (Daiichi Kogyo Seiyaku)” 5 parts by mass “ion-exchanged water”・ 200 parts by mass

  The above components were mixed and heated to 95 ° C., pre-dispersed for 10 minutes with a homogenizer (Ultra Turrax: manufactured by IKA), and then dispersed using a gorin homogenizer (pressure-jet pulverizer: manufactured by Gorin), A release agent particle dispersion A having a center diameter of 180 nm was obtained.

[Preparation of release agent particle dispersion B]
“Paraffin wax HNP9 (melting point 75 ° C .: manufactured by Nippon Seiki)” 45 parts by mass “cationic surfactant Neogen RK (Daiichi Kogyo Seiyaku)” 5 parts by mass “ion-exchanged water”・ 200 parts by mass

  The above components were mixed, heated to 85 ° C., pre-dispersed for 10 minutes with a homogenizer (Ultra Turrax: manufactured by IKA), and then dispersed using a Gorin homogenizer (pressure jet mill: manufactured by Gorin), A release agent particle dispersion B having a central diameter of 185 nm was obtained.

[Preparation of release agent particle dispersion C]
“Paraffin wax HNP3 (melting point 65 ° C .: manufactured by Nippon Seiki)” 45 parts by mass “Cationic surfactant Neogen RK (Daiichi Kogyo Seiyaku)” 5 parts by mass “ion exchange water”・ 150 parts by weight

  The above components were mixed and heated to 75 ° C., pre-dispersed for 10 minutes with a homogenizer (Ultra Turrax: manufactured by IKA), and then dispersed using a Gorin homogenizer (pressure jet mill: manufactured by Gorin), A release agent particle dispersion C having a center diameter of 210 nm was obtained.

Example 1
(Production of toner)
The core components listed in Table 1 below were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax: manufactured by IKA), and then 0.3 parts by mass of polyaluminum chloride in this solution was added. Then, the resultant was further dispersed with an ultra turrax for 5 minutes. Then, while stirring the inside of the flask with a heated oil bath, the temperature was raised to 51 ° C., held at 51 ° C. for 1 hour to form core agglomerated particles, and then 150 parts by mass of the resin particles D for the shell layer were added to the core / shell. Aggregated particles were produced.

  Thereafter, a 0.5N aqueous sodium hydroxide solution was added to adjust the pH of the solution to 6, and then the temperature was raised to 96 ° C. Then, the pH was adjusted to 4 with 0.5N nitric acid and held at 96 ° C for 5 hours. Then, it was cooled and neutralized with alkali, filtered, washed with water, separated into solid and liquid, and further vacuum dried to obtain a black toner.

(Measurement of physical properties of toner)
The toner of Example 1 was measured with a Coulter Counter TA-II type (manufactured by Coulter Co., Ltd.), and values of volume average particle diameter D50, volume average particle size distribution index GSDv, and number average particle size distribution index GSDp of the toner were obtained. The results are shown in Table 2 below.

(Addition of external additives and preparation of developer)
To 50 parts by mass of the toner of Example 1, 3.5 parts by mass of hydrophobic silica (TS720: manufactured by Cabot) was added as an external additive, and blended by a sample mill. Next, the toner of Example 1 in which an external additive was added to a ferrite carrier coated with 1% by mass of polymethyl methacrylate (PMMA) on the surface of ferrite particles having a volume average particle diameter of 50 μm was added with a toner concentration of 5 A developer was prepared by mixing to a mass%.

In addition, an image formation test was performed using an apparatus obtained by modifying Vivace 555 (manufactured by Fuji Xerox Co., Ltd.) as an image output evaluation apparatus. Using the developer, the amount of applied toner was adjusted to 4.5 g / m ² , and after image formation, the image was fixed on paper (PAL4: manufactured by Fuji Xerox Co., Ltd.) at a process speed of 220 mm / sec using an external fixing machine. As a fixing roll, a SUS roll having a diameter of 135 mm was used without being coated with a fluorine-based resin, and the Nip width as a contact portion between the heating roll and the pressure roll was 6 mm.
As a result, the obtained image was sufficiently fixed, and even at the time of fixing, the surface on which the paper image was formed and the surface of the fixing roll were smoothly peeled off. Moreover, there was no problem of offset resistance and a good image was obtained. The results are shown in Table 2 below.

The “peelability” in the fixing performance in Table 2 indicates the peelability of the paper from the fixing roll, and “○” indicates that the peelability is good. The grade was “△”, and the case where it was not good and there was a problem in use was designated “X”.
“Offset” refers to a phenomenon in which the formed image remains on the fixing roll. “Off” indicates that the image is good without any offset, and “△” indicates that there is no problem in use although it is not good. In the case where an offset occurs and there is a problem in use, “x” is given.
Furthermore, “fixing” refers to the fixability of an image on paper, and “○” indicates that the formed image is well fixed on the paper. “△”, and “x” when the fixing property is low and there is a problem in use.
“Image quality” in Table 2 is judged based on whether or not the desired image is clearly displayed when visually observed, and “○” indicates that the image quality is good. “△”, and “x” when there is a problem in use.

-Examples 2-7-
A toner was prepared in the same manner as in Example 1 except that the components used in the preparation of the toner and the aggregation temperature were changed to the conditions shown in Table 1. A developer was prepared. Table 2 shows the results of measuring the physical properties of the toner and the measurement results.

  The obtained image was sufficiently fixed, and even during fixing, the surface of the sheet on which the image was formed and the surface of the fixing roll peeled off smoothly. Moreover, there was no problem of offset resistance and a good image was obtained.

-Comparative Example 1-
As described in Table 1, a toner was prepared in the same manner as in Example 1 except that no styrene / diene resin dispersion was added to the components used in the preparation of the toner of Example 1, and the same as in Example 1. The developer of Comparative Example 1 was produced by external addition. Table 2 shows the results of measuring the physical properties of the toner and the measurement results.

  As a result of the image formation test, the fixability of the obtained image was sufficient, but at the time of fixing, there was no separation between the surface on which the image of the paper was formed and the surface of the fixing roll, and it stuck to the roll and offset, A sufficient image was not obtained. The results are shown in Table 2.

-Comparative Example 2-
As described in Table 1, with respect to the components used in the preparation of the toner of Example 2, the core particle resin dispersion D: 272 parts by mass was changed to 37 parts by mass, and the styrene / isoprene resin dispersion B was changed to 326 parts by mass. A toner was prepared in the same manner as in Example 2, and a developer in Comparative Example 2 was prepared by external addition in the same manner as in Example 4. Table 2 shows the results of measuring the physical properties of the toner and the measurement results.

  As a result of the image formation test, the peelability between the surface on which the paper image was formed and the surface of the fixing roll was insufficient at the time of fixing, and the image was wound and offset on the fixing roll. Evaluation was not possible. The results are shown in Table 2.

-Comparative examples 3, 4-
A toner was prepared in the same manner as in Example 1 except that the amount of the release agent dispersion added was changed as shown in Table 1 to change the content of the release agent in the toner. The developer of Comparative Examples 3 and 4 was produced by external addition. Table 2 shows the results of measuring the physical properties of the toner.

  As a result of the image formation test, in Comparative Example 3, the peelability from the roll and the offset property were poor, and the image quality deteriorated. In Comparative Example 4, the releasability and offset fixing performance were good, but the charging property was low, the toner granulation property was poor, the particle size distribution was deteriorated, and the image quality was poor.

-Example 8-
A developer was prepared in the same manner as in Example 1 using copper particles (number average particle size 0.49 μm, thermal conductivity 402 W / mK: 300 K) instead of hydrophobic silica as an external additive, and the physical properties of the toner. Measurements were made. As a result, the same good results as in Example 1 were obtained.

-Example 9-
Core agglomerated particles were produced without mixing the release agent dispersion A, and then the release agent dispersion A was mixed to form an intermediate layer. Thereafter, agglomerated particles were produced in the same manner as in Example 1 except that 150 parts by mass of the shell layer resin particles D were added to obtain a black toner.
Thereafter, in the same manner as in Example 1, external addition was performed to produce the developer of Example 9, and the physical properties of the toner were measured. As a result, the same good results as in Example 1 were obtained.
The content of the surface release agent measured by XPS (X-ray photoelectron spectrometer JPS-9000MX manufactured by JEOL Ltd.) was 0.5%. In addition, among the distance R from the center of the toner to the toner surface measured by a cross-sectional view of a TEM (transmission electron microscope JEM1010 manufactured by JEOL Ltd.), the content of the release agent in the region from the center to 1 / 3R is It was 3.2%.

Claims (3)

An electrophotographic toner that is used in an image forming apparatus having a fixing member having a surface energy of 5.0 × 10 ⁻² J / m ² or more and includes at least a binder resin, a colorant, and a release agent. There,
The content of the release agent is 10 to 40% by mass,
An electrophotographic toner comprising 5 to 50% by mass of a styrene-diene copolymer resin in the binder resin.   A resin fine particle dispersion (1) containing first resin fine particles containing at least a styrene-diene copolymer, a colorant dispersion containing a colorant, and a release agent dispersion containing a release agent are mixed. In addition, a resin fine particle dispersion (2) containing second resin fine particles is further added to the core aggregated particles thus aggregated to form a shell layer containing the second resin fine particles on the surface of the core aggregated particles, A method for producing an electrophotographic toner, characterized in that core / shell aggregated particles are formed and heated at a temperature higher than the glass transition point of the resin fine particles to fuse and coalesce. A charging step for charging the surface of the image carrier, an electrostatic latent image forming step for forming an electrostatic latent image according to image information on the charged surface of the image carrier, and developing the electrostatic latent image with toner. The image forming method includes a developing step for obtaining a toner image, a transfer step for transferring the toner image to the surface of the recording medium, and a fixing step for fixing the toner image transferred to the surface of the recording medium by heating. And
The surface energy of the fixing member used in the fixing step is 5.0 × 10 ⁻² J / m ² or more,
The toner includes at least a binder resin, a colorant, and a release agent;
The content of the release agent is 10 to 40% by mass,
An image forming method, wherein the binder resin contains 5 to 50% by mass of a styrene-diene copolymer resin.