JP2011197369A - Clear toner and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clear toner capable of giving a printed material having high glossiness (for example, glossiness of ≥80 at a measurement angle of 20°), causing no tacking even when printed materials are stacked, and having superior heat-resistant storage property.SOLUTION: The clear toner has a core-shell structure having at least a shell portion on the surface of a core portion, wherein the shell portion contains a polyester resin having a thermal conductivity of ≥6.0 W/(m K).

Description

  The present invention relates to a clear toner having a core / shell structure and an image forming method using the clear toner.

  Printed products such as photographic images and posters are produced by electrophotographic image forming apparatuses in addition to conventional silver halide photographic methods and gravure printing methods.

  For example, in the field of electrophotographic image forming technology such as copiers and printers, with the progress of technology such as digitization of exposure systems and toner diameter reduction, per 1200 dpi (dpi; 1 inch (2.54 cm) This makes it possible to reproduce a minute dot image of the number of dots.

  Also, a method of forming a toner image on each of a plurality of photosensitive drums, primarily transferring and superimposing the formed toner images on an intermediate transfer member, and secondary transferring the toner image formed on the intermediate transfer member to an image support For example, a technology that enables full-color image formation has also been developed. Thus, with the development of image forming technology, full-color images such as photographic images that require high resolution can be produced by these image forming technologies in addition to silver salt photography and conventional printing technologies.

  However, when a toner image is formed using toner, the toner image area has a certain level of gloss, but the white background (non-image area) has no gloss. Such an unbalanced glossy finish impairs the image quality of the printed matter, so countermeasures have been required.

  From such a background, as a technique for eliminating unevenness of gloss on an image (for balancing), a technique for forming an image using a toner obtained by removing a colorant component from a normal colored toner, also called a clear toner or a transparent toner. Began to be considered. Specifically, the clear toner is supplied to the entire surface of the image support on which the image is formed, and this is heated and fixed to form a clear toner layer on the entire surface of the image, thereby producing a printed matter having a uniform glossiness on the entire surface of the image. (For example, refer to Patent Document 1).

  Also disclosed is a technique for forming a glossy printed matter by forming a clear toner layer on an image formed by an electrophotographic printer or the like using a glossing device (for example, Patent Document 2, 3).

  In this technology, after a clear toner layer is formed on the entire surface of an image created by a printer, heating is performed with the surface of the clear toner layer in close contact with the belt to melt the clear toner, and then the surface of the clear toner layer is applied to the belt. The printed matter having gloss is produced by cooling in a close contact state and then spontaneously peeling from the belt.

  Also, a print image forming technique is disclosed in which a uniform gloss without unevenness can be obtained by paying attention to the difference in particle size between the color toner and the clear toner (see, for example, Patent Document 4).

  When the clear toner disclosed above is used, a glossy surface having a certain degree of smoothness can be formed on the image surface on which the clear toner layer is formed, and a glossy printed matter can be obtained. .

  However, the toner proposed above has a problem in practical use due to poor storage stability and low-temperature fixability.

  In order to improve storage stability and low-temperature fixability, a core / shell type clear toner has been studied (for example, see Patent Document 5).

  In the core / shell type clear toner, the softening point and the glass transition point of the resin forming the shell part are lowered in order to sufficiently exhibit the fixability of the core part.

Japanese Patent Laid-Open No. 11-7174 JP 2002-341619 A JP 2004-258537 A JP 2007-140037 A JP 2005-99079 A

  However, when the clear toner disclosed above is used, a printed matter having a certain degree of gloss can be obtained, but a printed matter having a high gloss (for example, a measurement angle of 20 ° and a glossiness of 80 or more) can be obtained. In addition, there is a problem that the printed matter sticks when the printed matter is left to stand (a problem that tacking occurs) and a problem that the clear toner aggregates during storage.

  In addition, when this clear toner is used, it is necessary to pass the gloss applying device at a low speed, and a clear toner that can produce a high gloss printed matter even if it is passed at a high speed has not yet been developed. is there.

  The present invention can produce a printed matter having high gloss (for example, a measurement angle of 20 ° and a glossiness of 80 or more). Further, even if the printed matter is placed on top of each other, tacking does not occur, and heat resistant storage stability is achieved. It is another object of the present invention to provide a clear toner having excellent characteristics.

  Another object of the present invention is to provide an image forming method for producing a printed matter having high gloss at a high speed using a gloss applying device.

  The object of the present invention is achieved by adopting the following configuration.

1. In the clear toner having a core-shell structure having a shell portion on the surface of the core portion,
A clear toner, wherein the shell portion has a polyester resin having a thermal conductivity of 6.0 W / (m · k) or more.

  2. The core part has at least a styrene acrylic resin, and the shell part has a polyester resin having a thermal conductivity of 6.0 W / (m · k) or more of 70% by mass or more and 100% by mass or less of the total amount of the shell part. 2. The clear toner as described in 1 above.

  3. 3. The clear toner as described in 1 or 2 above, wherein the softening point of the polyester resin having a thermal conductivity of 6.0 W / (m · k) or higher is 60 ° C. or higher and 120 ° C. or lower.

  4). 4. The clear toner according to any one of 1 to 3, wherein the polyester resin having a thermal conductivity of 6.0 W / (m · k) or more is an aromatic polyester resin.

5. at least,
Supplying a clear toner on an image support to produce a print image having a clear toner particle layer;
In the image forming method of forming a clear toner layer by heating and pressurizing the clear toner particle layer surface of the print image, and then producing a printed matter through a step of cooling the clear toner layer in a state of being in close contact with a belt,
The clear toner used in the image forming method has a core-shell structure having a shell portion on the surface of the core portion,
The image forming method, wherein the shell portion has at least a polyester resin having a thermal conductivity of 6.0 W / (m · k) or more.

  The clear toner of the present invention can produce a printed matter having a high gloss (for example, a measurement angle of 20 ° and a glossiness of 80 or more). Further, even if the printed matter is placed on top of each other, tacking does not occur. Excellent heat resistance storage effect.

  In addition, the image forming method according to the present invention has an excellent effect that a printed matter having a high glossiness (for example, a measurement angle of 20 ° and a glossiness of 80 or more) can be produced at high speed using a gloss applying device. .

It is a schematic diagram which shows an example which produces a printed matter combining an image forming apparatus and a glossiness imparting apparatus. It is a schematic diagram which shows an example of the glossiness imparting apparatus which can produce a highly glossy printed matter. FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus capable of forming a clear toner particle layer on the entire surface of an image support simultaneously with the generation of a color toner image. FIG. 4 is a schematic diagram illustrating an example of an apparatus in which a gloss imparting apparatus is attached to the image forming apparatus of FIG. 3. FIG. 4 is a schematic diagram illustrating an example of an apparatus in which a gloss applying device is attached instead of the fixing device of the image forming apparatus in FIG. 3.

  As a method for producing a high gloss printed matter at high speed using a gloss applying device, it is conceivable to reduce the softening point or glass transition point of the resin constituting the clear toner.

  In addition, it is conceivable to cope with a decrease in heat-resistant storage property caused by lowering the glass transition point with a core / shell structure.

  However, it is difficult to produce a high-gloss printed matter at high speed due to the presence of the shell portion only with the technology of the core-shell structure.

  To date, we have focused on the softening point and glass transition point of the resin that forms the shell, and have been studying how to balance the two conflicting properties (heat-resistant storage and low-temperature fixability). At present, no results have been obtained.

  The present inventors have provided a clear toner that can produce a printed matter having high gloss, and that does not cause tacking even when the printed matter is placed on top of each other, and has excellent heat-resistant storage properties. Study was carried out.

  In addition, the present inventors also examined the provision of an image forming method for producing a printed matter having high gloss at a high speed using a gloss applying device.

  In order to achieve the above object, the present inventors have studied the resin, paying attention to the ease of heat transfer (thermal conductivity) of the resin itself constituting the clear toner.

  As a result of various studies, it has been found that the object of the present invention can be achieved by using a clear toner prepared by using a polyester resin having a good thermal conductivity for the shell portion of the core-shell structure.

  A high gloss print has a gloss toner imparting device with a clear toner particle layer containing a polyester resin having a thermal conductivity of 6.0 W / (m · k) or more in the shell portion of the core-shell structure. It is presumed that the polyester resin can be obtained by being softened or melted at a high speed to form a clear toner layer having a smooth surface when heated.

  The reason why this clear toner is excellent in heat-resistant storage is that the surface of the clear toner has a shell portion containing a polyester resin having a softening point of 60 ° C. or higher and 120 ° C. or lower and a high softening point. For example, it is presumed that the styrene acrylic resin) is less likely to bleed out on the surface of the clear toner particles and can suppress the occurrence of aggregation during storage.

  It is presumed that the reason that tacking does not occur when the printed materials are superposed is that the surface of the printed material is covered with a melted polyester resin having a high softening point.

  The gloss imparting apparatus according to the present invention includes a heating and pressing apparatus that forms a clear toner layer having a smooth surface by heating and pressurizing the clear toner particle layer on the image support, and the image support after the heating and pressing. And a cooling device that cools in a state in which the cooling is performed. In this gloss imparting apparatus, since the printed material is peeled after the elasticity of the resin constituting the clear toner layer on the surface of the image support is restored, the smoothness of the printed material surface can be maintained, and the glossiness when measured at a measurement angle of 20 °. Can obtain a printed product with a high glossiness of 80 or more.

  Moreover, since the surface strength of the printed matter produced by the image forming method of the present invention is improved, it is preferably used for posters for outdoor posting.

  First, terms used in the present invention will be described.

《Printed matter》
The “printed product” as used in the present invention refers to a product in which a chestnut layer is formed on the entire surface of an image on an image support.

<Image support>
The “image support” capable of forming a high gloss print using the clear toner of the present invention is one that can form an image by a known method and can hold a clear toner layer. If it is not specifically limited, a well-known thing can be used. Known materials include plain paper from thin paper to thick paper, high-quality paper, art paper, or coated printing paper such as coated paper, commercially available Japanese paper or postcard paper, OHP plastic film, cloth, etc. It is done.

"image"
The “image” as used in the present invention refers to a medium that provides information to the user, such as a character image or an image. That is, not only the so-called image area where toner or ink is present on the image support, but also the area called non-image area where no toner or ink is present, which is called white background, The information can be provided to the user. In other words, the “image” in the present invention is composed of an “image region” formed using toner, ink, or the like and a “non-image region” called a white background where no toner, ink, or the like exists. You can also.

  In the present invention, the method for producing an image before forming the clear toner layer is not particularly limited, and the image is produced by a known image forming method such as an electrophotographic method, a printing method, an inkjet method, a silver salt photographic method, or the like. Things are the target.

《Clear toner layer》
The “clear toner layer” in the present invention is a layer formed with clear toner on the entire surface of the image support. The clear toner layer is a clear toner of 2 g / m ² or more and 15 g / m ² or less on the image support. It is preferable to form using.

  A clear toner layer formed with a clear toner amount in this range provides high gloss. In addition, it is excellent in tack resistance and preferable.

《Clear Toner》
The “clear toner” as used in the present invention is a particle that does not contain a colorant (for example, a color pigment, a coloring dye, black carbon particles, black magnetic powder, etc.) that shows coloration by the action of light absorption or light scattering. . The “clear toner” is usually colorless and transparent, but depending on the type and amount of the binder resin, wax, and external additive constituting the clear toner, the transparency may be slightly lowered. A toner that does not contain a colorant is called “clear toner”.

《Glossiness of printed matter》
The “glossiness of the printed material” as used in the present invention is a value obtained by quantitatively measuring the degree of reflection on the surface of the printed material obtained when the surface of the printed material is irradiated with light under predetermined conditions.

  The glossiness of the printed material is quantitatively measured by the following procedure.

  That is, the area of the clear toner layer of the printed matter prepared through the gloss applying device shown in FIG. 2 is measured according to “JIS Z8741 1997” at a 20 ° incident angle gloss measuring device (gross meter) “GMX-203” (Murakami). 5 points are randomly measured using a color technology laboratory, and the average value is used as the glossiness of the printed matter.

《Resin thermal conductivity》
The “thermal conductivity of resin” in the present invention is a value obtained by measurement by “laser flash method”.

  The laser flash method is a method in which one side of a flat resin test side is heated in a pal shape with a laser, and the thermal diffusivity is obtained from the temperature rise on the back side.

  The thermal conductivity of the resin is measured by emitting a laser beam from a laser oscillator and directly irradiating the surface of the sample (resin test side), and measuring the amount of heat and its time emitted from the back surface of the sample.

  The specific heat (Cp) and the thermal diffusivity (α) are derived from the obtained heat quantity and the time, and the thermal conductivity (λ) is calculated by the following equation.

Thermal conductivity: λ = α ・ Cp ・ ρ
(Ρ: Sample density)
In the present invention, the thermal conductivity is a value obtained by measurement under the following measurement conditions using “LF / TCM-FA8510B” (manufactured by Rigaku Corporation).

Measurement conditions Sample size: 1 cm diameter, 1 mm thick disc Temperature range to be measured: room temperature to 300 ° C
Next, the clear toner of the present invention will be described.

  1. The clear toner of the present invention has a core / shell structure comprising a core portion and a shell portion.

  2. The core part is preferably formed using a styrene-acrylic resin.

  3. The shell portion contains a polyester resin (hereinafter also referred to as a specific polyester resin) having a thermal conductivity of 6.0 W / (m · k) or more. The content of the specific polyester resin in the shell part is preferably 70% by mass or more and 100% by mass or less.

  4). The softening point of the specific polyester resin is preferably 60 ° C or higher and 120 ° C or lower.

  5. As the specific polyester resin, an aromatic polyester resin is preferable.

  By containing a specific polyester resin in an amount of 70% by mass or more and 100% by mass or less, it is possible to create a printed matter having a uniform glossiness at high speed using a gloss imparting device, and satisfy heat resistant storage property and tacking resistance. Can be preferable.

  By using a resin having a softening point of 60 ° C. or higher, heat-resistant storage stability and tacking resistance can be satisfied, and by using a resin having a temperature of 120 ° C. or lower, a printed matter having a uniform glossiness at high speed using a glossing device. Can be created.

<Clear toner with core / shell structure>
The clear toner of the present invention has a core-shell structure in which the surface of the core portion is covered with a shell portion having a specific polyester resin.

  The clear toner of the present invention is preferably one in which a shell part having a thickness of 100 nm or more and 3.0 μm or less is formed on the surface of a core part having an average circularity of 0.87 or more.

  In the present invention, a clear toner having a structure in which a shell part is formed on the surface of a core part having an average circularity of 0.87 or more using resin particles for a shell part having a volume-based median diameter of 60 nm or more and 1000 nm or less. When shell part resin particles having a volume-based median diameter of 60 nm or more and 1000 nm or less are used, the gap area between the attached shell part resin particles is reduced on the surface of the core part, and a uniform shell part without unevenness is formed. preferable.

  The volume-based median diameter of the resin particles for the shell part can be measured in a state where the resin particles are dispersed in the aqueous surfactant solution. As a measuring means for realizing such a measuring method, for example, particle size analysis using a dynamic light scattering method such as a dynamic light scattering nanotrack particle size distribution measuring apparatus “Microtrack UPA150” (manufactured by Microtrack) It can be measured using a device.

  In the present invention, it is preferable to form a shell portion having a uniform thickness as much as possible on the surface of the core portion. Therefore, the manufacturing method of the resin particles for the shell part is required to have a sharp particle size distribution, that is, a manufacturing method capable of preparing the resin particles so that the particle sizes of the individual resin particles can be made uniform. Preferably, a method of producing resin particles in an aqueous medium by a polymerization method such as emulsion polymerization or suspension polymerization can be mentioned. The resin particle production method by the polymerization method is easy to control various conditions during production by a known method, and can be produced while measuring the particle size of the resin particles by a known method. This is a preferable method for producing resin particles for a shell part having a diameter.

《Core part》
The core part is preferably produced using a styrene acrylic resin from the viewpoint of fixability.

  Examples of a styrene monomer, an acrylate monomer, and a methacrylic acid ester that can form a styrene acrylic resin are shown below, but are not limited to those shown below.

  Examples of the styrene monomer include the following. That is, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p- Examples thereof include n-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, and pn-dodecyl styrene.

  Examples of the acrylate monomer include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. , Stearyl acrylate, lauryl acrylate, phenyl acrylate and the like.

  Examples of the methacrylic acid ester monomer include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate. , Stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, and the like.

  These acrylic acid ester monomers or methacrylic acid ester monomers can be used alone or in combination of two or more. That is, forming a copolymer using a styrene monomer and two or more kinds of acrylate monomers, and forming a copolymer using a styrene monomer and two or more kinds of methacrylate monomers Either a styrene monomer, an acrylate monomer and a methacrylic acid ester monomer can be used together to form a copolymer.

(Average circularity of the core)
The average circularity of the core part is preferably 0.87 or more.

The “average circularity of the core part” is a value calculated by dividing the value obtained by adding the “circularity of the core part” defined by the following formula by the total number of core parts in which the measurement was performed. That is,
Circularity of the core portion = (perimeter of a circle having the same projection area as the core portion projection image) / (perimeter length of the core portion projection image)
The “average circularity of the core part” can be calculated using a flow type particle image analyzer represented by “FPIA-2100 (manufactured by Sysmex)”, for example.

  Preferably, ultrasonic dispersion treatment is performed for 1 minute in the liquid in which the core portion is dispersed, so that the core portion is uniformly dispersed. Then, it measures using "FPIA-2100" mentioned above. Measurement conditions are set to HPF (high magnification imaging) mode, and the number of HPF detections is set to an appropriate density of 3000 to 10,000. By making this range, the same measurement value with reproducibility can be obtained. In the present invention, the average circularity of the core portion refers to the value obtained by the above measurement.

<Shell part>
The shell portion contains a specific polyester resin. The shell part may contain other resins as necessary.

  It is preferable that the shell part contains 70% by mass or more and 100% by mass or less of the specific polyester resin based on the total amount of the resin particles for the shell part.

  Examples of other resins include styrene acrylic resins.

  The polyester resin used in the present invention has a high thermal conductivity of 6.0 W / (m · k) or more.

  The thermal conductivity of the polyester resin increases when the ester resin has many diols having a long alkyl chain.

  The long alkyl chain in the polyester resin is easy to move when heated, so that molecular blending is difficult to occur and the thermal conductivity is improved.

  Examples of the polyester resin having high thermal conductivity include aromatic polyester resins and aliphatic polyester resins. An aromatic polyester resin is preferred.

  Examples of the aromatic polyester resin include aromatic polyester resins represented by polyethylene terephthalate and polyethylene-2,6-naphthalate.

  Examples of the aliphatic polyester resin include polyvalent carboxylic acids having no aromatic ring in the molecule, such as adipic acid and sebacic acid, and polyhydric alcohols such as 1,4-butanediol and 1,8-octadiol. Mention may be made of polyester resins obtained by polycondensation.

  The softening point of the specific polyester resin used in the present invention is preferably 60 ° C. or higher and 120 ° C. or lower, and more preferably 80 ° C. or higher and 100 ° C. or lower. The glass transition point is preferably 35 ° C. or higher and 65 ° C. or lower.

  Next, the production of the clear toner of the present invention will be described.

<Manufacture of clear toner>
As a preferred production method of the clear toner of the present invention, various production methods can be adopted. As an example, a step of agglomerating resin particles to produce a core part, and a shell part on the surface of the core part A method for preparing a clear toner having a core / shell structure through a step of forming a shell part by adding resin particles for use can be mentioned.

  An example of a clear toner manufacturing method will be described in detail.

The clear toner of the present invention can be produced, for example, through the following steps.
(1) Dissolution / dispersion step of dissolving or dispersing the release agent in the radical polymerizable monomer (2) Polymerization step of preparing a dispersion of resin particles by polymerizing the radical polymerizable monomer (3) Dispersion Agglomeration and fusion process in which resin particles are agglomerated and fused to produce a core part (hereinafter also referred to as core particles) (4) a first aging process for aging the core particles with heat energy to adjust the shape (5) Shelling step of adding core part resin particles to the core particle dispersion and aggregating and fusing the shell part resin particles on the core particle surface to form core / shell structure particles ( 6) A second aging step in which the particles of the core / shell structure are aged by heat energy to adjust the shape of the particles of the core / shell structure (7) The dispersion of the particles having the adjusted shape is cooled, and the dispersion Solid-liquid separation of particles from Drying step of drying the washing step (8) washing the treated particles removed by,
(9) A step of adding an external additive to the dried particles as necessary.

  When producing the clear toner of the present invention, first, resin particles are agglomerated and fused to produce core particles as a core. Next, the resin particles for the shell part are added to the dispersion of the core particles, and the shell particle is formed by aggregating and fusing the resin particles for the shell part on the core particle surface to form the shell part. Particles having a core / shell structure coated with the above are prepared.

  The clear toner of the present invention preferably has a thin shell portion and a constant film thickness, and after forming the shell portion, a clear toner having a small particle size with a constant particle size and a uniform shape is preferable. In order to produce a clear toner having such a structure and shape, the core particles should be made to have a uniform shape with a uniform particle size, and the resin particles for the shell portion should be added to form a shell. become. Finally, when the shell is formed, the shape of the clear toner is controlled to give an appropriate shape. For that purpose, it is important to prepare core particles having a uniform shape with uniform particle diameters. is there. With such core particles, the resin particles forming the shell portion uniformly adhere to the surface, and as a result, clear toner particles having a very uniform film thickness can be produced.

  The core particles constituting the clear toner of the present invention are produced by a production method in which resin particles are aggregated and fused. The shape of the core particles is controlled, for example, by controlling the heating temperature in the aggregation / fusion process and the heating temperature and time in the first aging process.

  Of these, the time control in the first aging step is the most effective. Since the ripening step is intended to adjust the circularity of the core particles, the target circularity is reached by controlling this time.

  The core part constituting the clear toner of the present invention is prepared by, for example, dissolving or dispersing a release agent component in a polymerizable monomer that forms a resin, and then mechanically dispersing the fine particles in an aqueous medium to form a miniemulsion weight. A method in which composite resin particles formed through a step of polymerizing a radical polymerizable monomer (hereinafter also simply referred to as a polymerizable monomer) by a combined method is obtained by salting out and fusing as described later is preferably used. When the release agent component is dissolved in the polymerizable monomer, the release agent component may be dissolved or melted or dissolved.

  Next, the release agent and the charge control agent used when producing the clear toner of the present invention will be described.

(Release agent)
Examples of the release agent used in the present invention include polyethylene wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, dialkyl ketone wax such as distearyl ketone, carnauba wax, montan wax, trimethylolpropane tribehe. , Pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellitic acid Ester waxes such as tristearyl and distearyl maleate, amides such as ethylenediamine dibehenyl amide and trimellitic acid tristearyl amide Waxes and the like.

  Especially, as a mold release agent, a melting | fusing point is 50 to 100 degreeC.

  The addition amount of the release agent is preferably 1% by mass or more and 15% by mass or less, and more preferably 3% by mass or more and 12% by mass or less with respect to the entire clear toner.

  It is preferable to add a release agent having a melting point of 50 ° C. or more and 100 ° C. or less to 1% by mass or more and 15% by mass or less because the offset property is improved at a low fixing temperature.

  Melting | fusing point of a mold release agent can be performed using "DSC-7 differential scanning calorimeter" (made by Perkin Elmer).

  As a measurement procedure, 4.5 to 5.0 mg of the release agent is precisely weighed to 2 digits after the decimal point, sealed in an aluminum pan, and set in a DSC-7 sample holder. The reference used an empty aluminum pan. The measurement conditions were a measurement temperature of 0 ° C. to 200 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. Analysis was performed based on the data in Heat, and the peak top temperature of the release agent endothermic peak was defined as the release agent melting point.

(Charge control agent)
A charge control agent can be added to the clear toner of the present invention as necessary. As the charge control agent, known compounds can be used. For example, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or The metal complex etc. are mentioned. Examples of the metal contained include Al, B, Ti, Fe, Co, and Ni. The charge control agent is preferably colorless from the viewpoint of producing a clear toner. When the content of the charge control agent is 0.1% by mass or more and 20.0% by mass or less with respect to the entire clear toner, good results can be obtained.

<Developer>
The clear toner of the present invention can be used as a one-component clear toner developer and a two-component clear toner developer. When used as a two-component clear toner developer by mixing with a carrier, conventionally known materials represented by iron-containing magnetic particles such as iron, ferrite and magnetite can be used as the magnetic particles of the carrier. Ferrite particles or magnetite particles are preferred. The magnetic particles have a volume average particle size of 15 μm to 100 μm, more preferably 20 μm to 80 μm.

  The volume average particle diameter of the carrier can be measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathetic).

  The carrier is preferably a coating carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and known ones can be used, such as olefin resin, styrene resin, styrene acrylic resin, silicon resin, ester resin or fluorine-containing polymer resin. Can be used. The resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, styrene-acrylic resin, polyester resin, fluorine resin, phenol resin, etc. are used. be able to.

  The mixing ratio of the carrier and the clear toner is preferably in the range of carrier: clear toner = 1: 1 to 50: 1 in terms of mass ratio.

<How to create printed materials>
A printed matter having a clear toner layer formed of the clear toner of the present invention can be produced by using an apparatus in which a gloss imparting apparatus is combined with an electrophotographic image forming apparatus (electrophotographic apparatus).

  As an example of a method for producing a printed matter by combining an electrophotographic apparatus and a gloss imparting apparatus, a clear toner particle layer is formed by supplying clear toner to the entire surface of an image support on which an image is formed with each color toner by an electrophotographic method. Examples thereof include a method of creating a printed product having a clear toner layer through a gloss imparting device having a heating and pressing unit and a cooling and conveying unit after creating the printed image.

  FIG. 1 is a schematic diagram illustrating an example of creating a printed matter by combining an image forming apparatus and a gloss providing apparatus.

  In FIG. 1, P is an image support, A is a printed image, B is a clear toner particle layer, C is a printed material, D is a clear toner layer, T is a color toner image, and 1 is a process for creating a printed material by a glossing device. Reference numeral 2 denotes a print image creation process by the image forming apparatus.

  In FIG. 1, first, after forming a color toner image T on an image support P using the image forming apparatus 2, a print image A having a clear toner particle layer B is formed on the entire image support, In this method, the clear toner particle layer B is melted and cooled using the gloss applying device 1 to produce a printed product C having a clear toner layer D with a smooth surface.

  FIG. 2 is a schematic diagram illustrating an example of a gloss imparting apparatus capable of creating a high gloss print.

  In FIG. 2, P is an image support, A is a printed image, B is a clear toner particle layer, C is a printed matter, D is a clear toner layer, 1 is a gloss applying device, 10 is a heating and pressing unit, and 11 is a heating roll. , 12 is a pressure roll, 13 is a heating source, 14 is a pressure spring, 20 is a cooling conveyance unit, 21 is a belt, 22 is a cooling fan, 23 is cold air, 24 is a conveyance roll, 25 is a separation roll, and 30 is a print. Indicates the conveyance direction of the object.

  The gloss applying apparatus 1 shown in FIG. 2 includes a heating and pressing unit 10 and a cooling and conveying unit 20. The heating and pressing unit 10 sandwiches and conveys the print image A between a heating roll 11 and a pressure roll 12 that are driven at a constant speed, and heats and presses the conveyed print image A. That is, the clear toner particle layer B formed on the entire surface of the image support P is heated and pressurized to melt, and the clear toner particle layer B becomes a clear toner layer D having a uniform surface.

  The heating and pressing unit has a structure in which a heating source 13 is incorporated in the heating roll 11 and a pressing spring is incorporated in the pressing roll 14.

  The nip width between the heating roll and the pressure roll is preferably about 2 to 13 mm.

  The heating roll is preferably formed to have a predetermined outer diameter in which an elastic body layer made of silicone rubber or the like is coated on the surface of a metal base such as aluminum. A 300 to 350 W halogen lamp, for example, is disposed inside the heating roll as a heating source, and is heated from the inside so that the surface temperature of the heating roll becomes a predetermined temperature.

  The pressure roll is made by coating an elastic body layer made of silicone rubber or the like on the surface of a metal base such as aluminum, and further, made of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether resin) on the surface of the elastic body layer. It is preferable that the release layer is covered with a tube or the like so as to have a predetermined outer diameter. A 300 to 350 W halogen lamp, for example, can also be disposed inside the pressure roll as a heating source, and it is also preferable to heat from the inside so that the surface temperature of the pressure roll becomes a predetermined temperature.

  Next, the cooling conveyance unit 20 will be described. The cooling conveyance unit 20 includes an endless belt 21 rotatably supported by the heating roll 11 and a plurality of rolls 24 and a cooling unit.

  The belt is stretched around a heating roll and a plurality of rolls so as to be rotatable, and is driven at a predetermined moving speed by a driving source (not shown).

  Since the belt forms an adhesive surface with the melted clear toner layer surface and conveys the image support P through the melted clear toner layer surface, the belt is made of a material having a certain degree of heat resistance and mechanical strength. Can be produced. Examples thereof include heat-resistant film resins such as polyimide, polyether polyimide, PES (polyether sulfone resin), and PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether resin). Further, it is preferable to provide a release layer excellent in release properties of fluororesin such as PTFE (polytetrafluoroethylene) and PFA and silicone rubber on at least the clear toner layer contact surface side of the heat resistant film resin. .

  The thickness of the belt is not particularly limited as long as the image support P can be conveyed through the adhesive surface with the melted clear toner layer surface. The thickness of the heat resistant film resin is preferably 20 to 80 μm, the thickness of the release layer is preferably 10 to 30 μm, and the total thickness of the belt is preferably 20 to 110 μm. As a preferred embodiment, a polyimide endless film having a thickness of 80 μm and a silicone rubber layer having a thickness of 30 μm may be coated.

  Next, the cooling means will be described. The cooling means is provided with cooling fans 22 on the inner surface side of the belt and the lower side of the belt, and the image support P on which the clear toner layer is formed is carried on the belt 11 by the cold air of the cooling fan. Cool with force.

  The clear toner layer on the image support P is forcibly cooled by cold air from a cooling fan while being conveyed by the belt, thereby promoting solidification. The clear toner layer is sufficiently cooled and solidified when conveyed to the vicinity of the end of the belt where the separation roll 25 is disposed, and the printed matter C is peeled from the belt at the end.

  FIG. 3 is a schematic diagram showing an example of an image forming apparatus capable of creating a print image having a clear toner particle layer on the entire image support simultaneously with the creation of a color toner image.

  The image forming apparatus 2 shown in FIG. 3 is normally also called a “tandem color image forming apparatus”, and includes a clear toner particle layer forming unit 20S, a plurality of sets of toner image forming units 20Y, 20M, 20C, and 20Bk, and a belt shape. The intermediate transfer belt 26, the paper feeding device 40, the fixing device 50, and the like.

  An image reading unit is installed on the upper portion of the image forming apparatus 2. The document placed on the document table is scanned and exposed by the optical system of the document image scanning exposure apparatus of the image reading unit, and read by the line image sensor. The analog signal photoelectrically converted by the line image sensor is subjected to analog processing, A / D conversion, shading correction, image compression processing, etc. in the control means, and then input to the exposure units 30S, 30Y, 30M, 30C, and 30Bk. The

  In the present invention, the constituent elements are collectively indicated by reference numerals with alphabetic suffixes omitted, and the individual constituent elements are indicated by S (clear toner), Y (yellow), M (magenta), C (Cyan) and Bk (black) are indicated by reference numerals with suffixes.

  The image forming apparatus 2 in FIG. 3 includes a clear toner particle layer forming unit 20S that forms a clear toner particle layer on the entire surface of the image support via an intermediate transfer belt 26, a yellow image forming unit 20Y that forms a yellow toner image, It has a magenta image forming unit 20M that forms a magenta toner image, a cyan image forming unit 20C that forms a cyan toner image, and a black image forming unit 20Bk that forms a black toner image. The image forming unit 20 includes band electrodes 22 (22S, 22Y, 22M, 22C, 22Bk) disposed around a drum-shaped photoconductor 21 (21S, 21Y, 21M, 21C, 21Bk) as image carriers. It has an exposure unit 30 (30S, 30Y, 30M, 30C, 30Bk), a developing device 24 (24S, 24Y, 24M, 24C, 24Bk) and a cleaning device 25 (25S, 25Y, 25M, 25C, 25Bk).

  The photoreceptor 21 is composed of an organic photoreceptor in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer peripheral surface of a drum-shaped metal base, and the width direction of the image support P to be conveyed is, for example, They are arranged so as to extend in the direction perpendicular to the paper surface in FIG. As the resin constituting the photosensitive layer, for example, a known photosensitive layer forming resin such as a polycarbonate resin is used. In the embodiment shown in FIG. 3, the configuration example using the drum-shaped photoconductor 21 is described. However, the configuration is not limited to this, and a belt-shaped photoconductor may be used.

  The developing device is a two-component developer comprising toners and carriers of different colors of clear toner (S), yellow toner (Y), magenta toner (M), cyan toner (C) and black (Bk) according to the present invention, respectively. Is included.

The intermediate transfer belt 26 that is an intermediate transfer member is rotatably supported by a plurality of rollers. As the intermediate transfer belt 26, an endless belt having a volume resistance of 10 ⁶ to 10 ¹² Ω · cm is preferably used. The intermediate transfer belt is formed using a known resin material such as polycarbonate (PC), polyimide (PI), polyamideimide (PAI), polyvinylidene fluoride (PVDF), tetrafluoroethylene-ethylene copolymer (ETFE), and the like. can do. The thickness of the intermediate transfer belt is preferably 50 to 200 μm.

  The clear toner particle layer and each color toner image formed on each photoreceptor 21 (21S, 21Y, 21M, 21C, 21Bk) by the clear toner particle layer forming unit 20S and the toner image forming units 20Y, 20M, 20C, 20Bk The image is sequentially transferred (primary transfer) onto the rotating intermediate transfer belt 26 by the primary transfer rollers 27 (27S, 27Y, 27M, 27C, and 27Bk), and a full color image combined with the clear toner particle layer is formed on the intermediate transfer belt 26. It is formed. On the other hand, after the image transfer, the residual toner is removed from the photoreceptor 21 (21Y, 21M, 21C, 21Bk) by the cleaning devices 25 (25S, 25Y, 25M, 25C, 25Bk) of the respective colors.

  The image support P accommodated in the paper storage unit (tray) 41 of the paper supply device 40 is supplied by the first paper supply unit 42, and is supplied with paper supply rollers 43, 44, 45A, 45B, registration rollers (second rollers). The sheet is conveyed to the secondary transfer roller 29 through the paper feed unit 46 and the like, and the clear toner particle layer and the color image are transferred onto the image support P (secondary transfer).

  Note that the three-stage paper storage units 41 arranged vertically in the vertical direction below the image forming apparatus 2 have substantially the same configuration, and thus are given the same reference numerals. The three-stage sheet feeding units 42 have the same configuration and are therefore given the same reference numerals. The paper storage unit 41 and the paper supply unit 42 are collectively referred to as a paper supply device 40.

  The image support P to which the clear toner particle layer and the full-color image are transferred is sandwiched in the fixing device 50, and the clear toner and each toner are melted and solidified by the action of heating and pressing. In this manner, the fixing device 50 fixes the full-color toner image having the clear toner particle layer formed on the entire surface of the image support on the image support P. The image support P is nipped and conveyed by the conveyance roller pair 57, is discharged from the discharge roller 47 provided in the discharge conveyance path, and is placed on a discharge tray 90 outside the apparatus.

  On the other hand, after the clear toner particle layer and the color toner image are transferred onto the image support P by the secondary transfer roller 29, the intermediate transfer belt 26 in which the image support P is further separated by curvature is cleaned for the intermediate transfer belt. The residual toner is removed by the device 261.

  FIG. 4 is a schematic diagram illustrating an example of an apparatus in which a gloss providing device is attached to the image forming apparatus of FIG.

  FIG. 4 is a diagram in which the gloss imparting device 1 of FIG. 2 is arranged at the location of the paper discharge unit 90 of the image forming apparatus 2 of FIG. 3 and is subjected to fixing processing by the fixing device 50 built in the image forming apparatus 2 of FIG. The image support P is further subjected to the melting / pressurizing treatment of the clear toner particle layer formed on the entire surface of the image support by the gloss applying device 1.

  FIG. 5 is a schematic diagram illustrating an example of an apparatus in which a gloss applying device is attached instead of the fixing device of the image forming apparatus 2 illustrated in FIG. 3.

  FIG. 5 is a diagram in which the gloss applying device 1 of FIG. 2 is attached in place of the fixing device 50 of the image forming apparatus 2 shown in FIG. 3, and the clear toner particles transferred onto the image support P by the secondary transfer roller 29. The layer and the color toner image can be fixed and glossed simultaneously by the glossing device 1. According to the apparatus shown in FIG. 5, the gloss imparting apparatus 1 can be in a form incorporated in the image forming apparatus 2, which is preferable for realizing a compact apparatus.

  Examples of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

<Preparation of clear toner>
The clear toner was produced by forming a shell portion on the surface of the core particle.

<Preparation of resin particle dispersion for core>
The resin particles used for preparing the core resin particle dispersion were prepared by two-stage polymerization.

(First stage polymerization)
A reaction vessel equipped with a stirrer, temperature sensor, cooling tube, temperature controller, and nitrogen introducing device is charged with a solution in which 3 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate is dissolved in 900 parts by mass of ion-exchanged water. After heating to 80 ° C., a solution obtained by dissolving the following “first stage monomer mixture” at 80 ° C. is added, and a mechanical disperser “CLEARMIX” having a circulation path (M Technique Co., Ltd.) For 1 hour to prepare a dispersion containing emulsified particles (oil droplets).

First stage polymerization monomer mixture liquid Styrene 236 parts by mass n-butyl acrylate 105 parts by mass Methacrylic acid 20 parts by mass n-octyl mercaptan 6.5 parts by mass Electol WEP-3 120 parts by mass A polymerization initiator solution in which 12 parts by mass of potassium was dissolved in 235 parts by mass of ion-exchanged water was added, and this system was heated and stirred at 80 ° C. for 1 hour to prepare a resin particle dispersion.

(Second stage polymerization)
A solution prepared by dissolving 12 parts by mass of potassium persulfate in 235 parts by mass of ion-exchanged water was added to the above resin particle dispersion, and this system was subjected to the following “second-stage polymerization monomer mixing” under a temperature condition of 80 ° C. The liquid was added dropwise over 3 hours.

Second-stage polymerization monomer mixture liquid Styrene 459 parts by mass n-butyl acrylate 126 parts by mass n-octyl mercaptan 32 parts by mass After completion of dropping, the mixture was heated and stirred for 1 hour, and then cooled to 28 ° C. A resin particle liquid was prepared. This is referred to as “core resin particle dispersion”.

<Preparation of dispersion of resin particle A1 for shell part>
The following “mixed solution 1” was heated to 240 ° C. in a reduced-pressure atmosphere and subjected to dehydration condensation for 6 hours to prepare “resin A1 for shell portion”.

Mixture 1
Adipic acid 585 parts by mass 1,4-butanediol 365 parts by mass Dibutyltin 2 parts by mass The obtained “resin A1 for shell part” 200 parts by mass, ion-exchanged water 780 parts by mass, anion activator 16 parts by mass The mixture was stirred with a homogenizer “Ultra Tarax” (manufactured by IKA Japan) while being heated, and then cooled to room temperature to prepare “dispersion of resin particles A1 for shell part” having a number average particle size of 160 nm.

  The heat conductivity of the obtained resin A1 for shell part was 8.0. The thermal conductivity of the shell portion resin A1 is a value obtained by melting the shell portion resin particles A1 to prepare a measurement sample having a thickness of 1 mm and a length and width of 1 cm, and measuring by the measurement method described above. .

  The obtained resin A1 for shell part had a softening point of 51 ° C. and a melting point of 50 ° C. In addition, the softening point and melting | fusing point of resin A1 for shell parts are the values obtained by measuring with a well-known measuring method.

<Preparation of dispersion of resin particle A2 for shell part>
The following “mixed solution 2” was heated to 240 ° C. in a reduced-pressure atmosphere and dehydrated and condensed for 6 hours to prepare “resin A2 for shell portion”.

Mixture 2
665 parts by weight of terephthalic acid 915 parts by weight of bisphenol A 1.5 parts by weight of dibutyltin 200 parts by weight of the obtained “resin A2 for shell part”, 780 parts by weight of ion-exchanged water, and 16 parts by weight of an anion activator were heated to 95 ° C. Then, after mixing and stirring with a homogenizer “Ultra Tarax” (manufactured by IKA Japan), the mixture was cooled to room temperature, and a “dispersed liquid of shell part resin particles A2” having a number average particle size of 160 nm was produced.

  The obtained shell portion resin A2 had a thermal conductivity of 6.0.

  The obtained resin A2 for shell part had a softening point of 80 ° C. and a melting point of 65 ° C.

<Preparation of dispersion of resin particle A3 for shell part>
The following “mixed solution 3” was heated to 240 ° C. in a reduced-pressure atmosphere and dehydrated and condensed for 6 hours to prepare “resin A3 for shell portion”.

Mixture 3
665 parts by weight of terephthalic acid 250 parts by weight of 1,4-butanediol 2.5 parts by weight of dibutyltin 200 parts by weight of the obtained “resin A3 for shell part”, 780 parts by weight of ion-exchanged water, and 16 parts by weight of anion activator The mixture was stirred and stirred with a homogenizer “Ultra Tarax” (manufactured by IKA Japan) while being heated to ° C., and then cooled to room temperature to prepare “dispersion of resin particles A3 for shell part” having a number average particle diameter of 160 nm.

  The thermal conductivity of the obtained shell part resin A3 was 15.0.

  The obtained resin A3 for shell part had a softening point of 70 ° C. and a melting point of 65 ° C.

<Preparation of dispersion of resin particle A4 for shell> (for comparison)
The following “mixed solution 4” was heated to 240 ° C. in a reduced-pressure atmosphere and dehydrated and condensed for 8 hours to prepare “resin A4 for shell portion”.

Mixture 4
810 parts by weight of sebacic acid 760 parts by weight of terephthalic acid 2 parts by weight of dibutyltin 200 parts by weight of “resin A4 for shell part” was dissolved in 300 parts by weight of THF at room temperature, and this solution was dissolved in a homogenizer “Ultra Tarax” (IKA Japan). The mixture was added to 800 mass of ion-exchanged water mixed and stirred by a company, and emulsified. The emulsified liquid was heated to 70 ° C. to distill off excess THF, thereby preparing “dispersion of resin particles A4 for shells” having a number average particle diameter of 160 nm.

  The heat conductivity of the obtained resin A4 for shell part was 3.5.

  The obtained resin A4 for shell part had a softening point of 79 ° C. and a melting point of 64 ° C.

<Preparation of dispersion of resin particle B1 for shell part>
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, temperature controller, and nitrogen introducing device, 2.0 parts by mass of the anionic active agent (Structural Formula 1) shown below is dissolved in 3000 parts by mass of ion-exchanged water. The surfactant solution was charged and the internal temperature was raised to 80 ° C. while stirring at a rate of 230 rpm under a nitrogen stream.

(Structural formula 1)
_{C 10 H 21 (OCH 2)} CH 2) 2 SO 3 Na
To this surfactant solution, an “initiator solution” in which 10 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 parts by mass of ion-exchanged water was added. It dripped over time and superposed | polymerized by heating and stirring this system at 80 degreeC for 1 hour, and produced "the dispersion liquid of the resin particle B1 for shell parts."

Monomer mixed liquid Styrene 528 parts by mass n-butyl acrylate 176 parts by mass Methacrylic acid 120 parts by mass n-octyl mercaptan 22 parts by mass <Preparation of Clear Toner 1>
(Formation of core particle 1)
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, temperature control device, and nitrogen introduction device, 450 parts by mass of “resin particle dispersion for core” in terms of solid content and polyoxyethylene-2-dodecyl ether sulfate 2 parts by mass of sodium and 900 parts by mass of ion-exchanged water were charged and the liquid temperature was adjusted to 25 ° C., and then a pH was adjusted to 10 by adding a 25% by mass aqueous sodium hydroxide solution.

  Next, an aqueous solution in which 70 parts by mass of magnesium chloride was dissolved in 105 parts by mass of ion-exchanged water was added over 30 minutes at 30 ° C. with stirring, and the temperature was increased after holding for 3 minutes. The particle growth reaction was continued while maintaining the temperature at 80 ° C.

In this state, "Coulter Multisizer 3" measured in median diameter on the volume basis of agglomerated particles using a particle size measuring apparatus (manufactured by Coulter Electronics, Inc.) (D _50), the median diameter (D ₅₀₎ in volume-based When the particle size became 6.2 μm, an aqueous solution in which 15 parts by mass of sodium chloride was dissolved in 58 parts by mass of ion-exchanged water was added to stop the particle growth to form “core particle 1”.

(Formation of shell part)
Subsequently, 34 parts by mass of the “dispersion of resin particles A1 for shell” in terms of solid content was added to the system containing the core particles 1 over 25 minutes.

  A small amount of the obtained dispersion is sampled and centrifuged, and after confirming that the supernatant is transparent, an aqueous solution in which 60 parts by mass of sodium chloride is dissolved in 232 parts by mass of ion-exchanged water is added to form a shell. Furthermore, by heating and stirring at a liquid temperature of 88 ° C. as a ripening step, particles are formed while progressing fusion between particles until the average circularity is 0.960 as measured by “FPIA-2100”. Thereafter, the solution was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 2.0, and stirring was stopped.

The particles produced in the above process are solid-liquid separated with a basket-type centrifuge “MARK III Model No. 60 × 40” (Matsumoto Kikai Co., Ltd.) to form a wet cake of clear toner particles. In the basket type centrifuge, the filtrate is washed with ion exchange water at 45 ° C. until the electric conductivity of the filtrate reaches 5 μS / cm, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). “Clear toner base particle 1” was prepared by drying to 0% by mass. The volume-based median diameter (D ₅₀ ) of the obtained clear toner base particles 1 was 6.8 μm.

(External additive treatment)
“Clear toner 1” was prepared by adding the following external additives to the “clear toner base particles 1” obtained above and performing an external addition treatment with a Henschel mixer (manufactured by Mitsui Miike Mining Co., Ltd.).

External additive Hexamethylsilazane-treated silica (average primary particle size 12 nm) 1.0 part by mass n-octylsilane-treated titanium dioxide 0.3 part by mass External addition treatment with a Henschel mixer was performed at a peripheral speed of 35 m of stirring blades. / Second, treatment temperature 35 ° C., treatment time 15 minutes.

<Preparation of clear toner 2-4>
“Clear toners 2 to 4” were prepared in the same manner except that “the dispersion of the resin particles A1 for the shell part” was changed to “the dispersions of the resin particles A2 to A4 for the shell part” used in the preparation of the clear toner 1. .

<Preparation of clear toner 5>
The “dispersed liquid of shell part resin particles A1” (34 parts by mass in terms of solid content) used in the production of clear toner 1 was replaced with the “dispersed liquid of shell part resin particles A1” (in terms of solids 31.6 parts by mass). Part) and “shell part resin particles B1” (2.4 parts by mass in terms of solid content) were changed to a premixed mixed dispersion, and “Clear Toner 5” was produced in the same manner as Clear Toner 1. did.

<Preparation of Clear Toner 6-8>
Clear toner except that the mass parts of “dispersion liquid of shell resin particles A1” and “dispersion liquid of shell resin particles B1” used in the production of clear toner 5 are changed as shown in Table 1. “Clear toners 6 to 8” were prepared in the same manner as in preparation of No. 5.

<Preparation of clear toner 9>
The “dispersion of resin particles A1 for shell part” (34 parts by mass in terms of solid content) used in the preparation of clear toner 1 is replaced with “dispersion of resin particles B1 for shells” (34 parts by mass in terms of solids). A “clear toner 9” was prepared in the same manner as the preparation of the clear toner 1 except for the change.

<Preparation of Clear Toner 10>
The clear toner 1 shell portion was not formed, and only the core particles were designated as “clear toner 10”.

  Table 1 shows the members used for producing the clear toner.

<Evaluation>
The apparatus shown in FIG. 4 was set under the following conditions, and the clear toner prepared above was sequentially loaded to produce a printed matter having a clear toner layer on the entire A4 size image support.

Setting conditions (a) Development amount of clear toner on image support: 4 g / m ²
(B) Belt material: a PFA layer (thickness 10 μm) disposed on a polyimide film (thickness 50 μm) (c) Belt surface roughness (initial surface roughness): Ra 0.4 μm
(D) Specifications of heating and pressure rolls Heating roll: an aluminum base having an outer diameter of 100 mm and a thickness of 10 mm provided with a 3 mm thick silicone rubber layer Pressurizing roll: made of aluminum having an outer diameter of 80 mm and a thickness of 10 mm A silicon rubber layer having a thickness of 3 mm is provided on a substrate. A halogen lamp is disposed inside each of a heating roll and a pressure roll. The surface temperature of the heating roll is 155 ° C., and the surface temperature of the pressure roll is 115 ° C. (Temperature control by thermistor)
Nip width of heating roll and pressure roll: 11mm
(E) Surface temperature of image support at peeling roll position: set to be 50 ± 5 ° C. (f) Distance from heating and pressure roll nip to peeling roll position: 620 mm
(G) Image support conveyance speed: 150 mm / second (h) Image support conveyance direction: A4 size image support is conveyed in the vertical direction (i) Evaluation environment: normal temperature and normal humidity environment (temperature 20 ° C., relative (Humidity 50% RH)
As the image support, commercially available “OK top coat paper (basis weight 157 g / m ² , paper thickness 131 μm) (manufactured by Oji Paper Co., Ltd.)” was used.

(Evaluation of gloss of printed matter)
The gloss of the printed matter was measured using a gloss meter “GMX-203 (manufactured by Murakami Color Research Laboratory Co., Ltd.)” at an incident angle of 20 ° based on “JIS Z8741 1997”. The glossiness was measured by randomly selecting five printed materials and taking the average value. The glossiness was evaluated as 80 or more.

(Evaluation of tacking)
For the evaluation of tacking, the clear toner layer surface of the printed material used in the above glossiness evaluation was superposed, and a weight was placed on the superposed portion so that a load corresponding to 80 g / cm ² was applied, and a constant temperature of 60 ° C. and 50% RH. It was allowed to stand for 3 days in a humidity chamber. After leaving, the image defects generated in the printed material when the two printed materials were peeled off were evaluated according to the following evaluation criteria. In addition, ◎, ○, and Δ are acceptable.

Evaluation Criteria A: There is no slight sticking when peeling the superimposed printed matter, and no image defect occurs. ○: A zipping sound is made when peeling the superimposed printed matter, but no image defect occurs. Δ: When peeling the overlapped printed matter, gloss unevenness slightly occurs in both printed matters, but there is almost no defect as an image. ×: Due to the transition of the clear toner layer when peeling the overlapped printed matter. Peeling is recognized and there is a problem in practical use.

(Evaluation of heat-resistant storage properties)
Evaluation of heat-resistant storage property was evaluated by the amount (ratio) of aggregates remaining on the sieve after 100 g of each clear toner was left for 24 hours at 55 ° C. and 90% RH, sieved with a sieve having an opening of 45 μm. did. ◎ and ○ are acceptable.

Evaluation Criteria ◎: Less than 5% on the sieve, very little aggregation and excellent (no generation of aggregates even if transported in summer without any insulation packaging)
○: The amount on the sieve is 5-30% and the amount of agglomeration is small and good (no agglomeration even if transported in the summer with cardboard packaging only)
×: The amount on the sieve is more than 30%, the amount of aggregation is large, and there is a practical problem (requires cold transport)
Table 2 shows the evaluation results.

  As is apparent from Table 2, “Examples 1 to 7” using the clear toner of the present invention satisfy all the evaluation items. On the other hand, it can be seen that “Comparative Examples 1 to 3” using the clear toner of the comparative example has a problem in any of the evaluation items.

DESCRIPTION OF SYMBOLS 1 Creation process of printed matter by glossiness imparting device 2 Print image creation step by image forming apparatus P Image support A Print image B Clear toner particle layer C Print product D Clear toner layer T Color toner image

Claims (5)

In the clear toner having a core-shell structure having a shell portion on the surface of the core portion,
A clear toner, wherein the shell portion has a polyester resin having a thermal conductivity of 6.0 W / (m · k) or more. The core part has at least a styrene acrylic resin, and the shell part has a polyester resin having a thermal conductivity of 6.0 W / (m · k) or more of 70% by mass or more and 100% by mass or less of the total amount of the shell part. The clear toner according to claim 1. The clear toner according to claim 1, wherein a softening point of the polyester resin having a thermal conductivity of 6.0 W / (m · k) or more is 60 ° C. or more and 120 ° C. or less. The clear toner according to claim 1, wherein the polyester resin having a thermal conductivity of 6.0 W / (m · k) or more is an aromatic polyester resin. at least,
Supplying a clear toner on an image support to produce a print image having a clear toner particle layer;
In the image forming method of forming a clear toner layer by heating and pressurizing the clear toner particle layer surface of the print image, and then producing a printed matter through a step of cooling the clear toner layer in a state of being in close contact with a belt,
The clear toner used in the image forming method has a core-shell structure having a shell portion on the surface of the core portion,
The image forming method, wherein the shell portion has at least a polyester resin having a thermal conductivity of 6.0 W / (m · k) or more.

Images