JP5633351B2 - Clear toner and image forming method - Google Patents

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 salt photographic methods and gravure printing methods.

  For example, in the field of electrophotographic image forming technology such as copiers and printers, 1200 dpi (dpi; 1 inch (2.54 cm)) is developed along with the progress of technology such as digitization of exposure systems and toner diameter reduction. 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. The technique to do is disclosed (for example, refer 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 clear toner proposed above cannot be said to have sufficient storage stability and low-temperature fixability.

  To improve storage stability and low-temperature fixability, a toner having a core / shell structure has been studied (for example, see Patent Document 5).

  In the toner having a core / shell structure, the softening point and the glass transition point of the resin forming the shell layer 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, if the printed material is left on top of it, a phenomenon called so-called document offset occurs in which the clear toner is partially transferred to the back surface of the other printed material that has been superimposed on the printed material, and the glossiness of that portion is lost. There was a problem of being broken. There is also a problem that the clear toner aggregates during storage.

  In addition, when this clear toner is used, it is necessary to pass through the gloss applying device at a low speed, and it has been developed that a clear toner capable of producing a high gloss print even if it is passed at a high speed has not been developed yet. there were.

  An object of the present invention is to produce a printed matter having a high gloss (for example, a measurement angle of 20 ° and a glossiness of 80 or more). An object of the present invention is to provide a clear toner having excellent heat-resistant storage properties.

  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 a clear toner having a core-shell structure having a shell layer on the surface of the core portion, the resin constituting the shell layer is a vinyl resin, and the vinyl resin is a copolymer component and methyl methacrylate is used as a copolymerization component. A clear toner comprising 55% by mass to 95% by mass and containing 5% by mass to 15% by mass of methacrylic acid, and the resin constituting the core part is a styrene-acrylic resin. .
2 .
2. The clear toner according to 1 above, wherein the glass transition point of the vinyl resin constituting the shell layer is 45 ° C. or higher and 60 ° C. or lower.
3 .
3. The clear toner as described in 1 or 2 above, wherein the vinyl resin constituting the shell layer has a weight average molecular weight of 8,000 to 15,000.
4 .
4. The clear toner according to any one of 1 to 3 , wherein a glass transition point of the resin constituting the core portion is 25 ° C. or higher and 40 ° C. or lower.
5 .
5. The clear toner as described in any one of 1 to 4 above, wherein the resin constituting the core part has a weight average molecular weight of 15,000 or more and 25,000 or less.
6 .
At least a step of supplying a clear toner on the image support to create a print image having a clear toner particle layer, and heating and pressurizing the surface of the clear toner particle layer of the print image to form a clear toner layer; In the image forming method for producing a printed matter through the step of cooling the clear toner layer in close contact with the toner, the clear toner used in the image forming method has a shell layer on the surface of the core portion. The resin having a core-shell structure and constituting the shell layer is a vinyl resin, the vinyl resin contains 55% by mass to 95% by mass of methyl methacrylate as a copolymerization component, 5 and those containing by mass% to 15 mass%, the resin constituting the core portion is a styrene - imaging side, characterized in that the acrylic resin .

  With the clear toner of the present invention, a printed matter having a high gloss (for example, a measurement angle of 20 ° and a glossiness of 80 or more) can be produced with the above-described configuration, and the printed matter is further stacked. However, there is no document offset and the heat storage stability is excellent.

  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. .

Schematic diagram showing an example of a method for forming a glossy printed matter through a step of forming a clear toner particle layer on an image support having a toner image and a step of forming a glossy clear toner layer by heating and pressurizing the clear toner particle layer It is. It is a schematic diagram showing an example of a method for producing a high-gloss printed material through a high-gloss applying device from a glossy printed material having a glossy clear toner layer. It is a schematic diagram which shows an example of the high gloss provision apparatus used for preparation of a high gloss printed matter. Simultaneously with the creation of the toner image, a clear toner particle layer is formed on the image support, and then the clear toner particle layer is melted by a heat and pressure fixing device to form a glossy clear toner layer, thereby producing a glossy printed matter. 1 is a schematic diagram showing an example of an electrophotographic image forming apparatus that can be used. FIG. 3 is a schematic diagram illustrating an example of an apparatus in which a high gloss applying apparatus is attached to the electrophotographic image forming apparatus of FIG. 2. FIG. 3 is a schematic diagram illustrating an example of a device in which a high gloss applying device is attached instead of the heat and pressure fixing device of the electrophotographic image forming apparatus of FIG. 2.

  As a method of creating a high gloss print at high speed using a gloss imparting 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 and high-gloss printed matter by the existence of the shell layer only by the technique of the core-shell structure.

  In order to solve this problem, attention has been paid to the molecular weight, softening point, or glass transition point of the resin forming the shell layer, and studies have been made to balance two conflicting properties (heat resistant storage property and low temperature fixing property). However, the current situation is that satisfactory results have not been obtained.

  The present inventors can create a printed matter having high gloss (hereinafter also referred to as a highly glossy printed matter), and even when the printed matter is placed on top of each other, document offset does not occur and the heat resistant storage property is improved. We also studied the provision of clear toners with excellent characteristics. 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 investigations, when a clear toner produced using a vinyl resin containing 55% by mass or more of methyl methacrylate having a good thermal conductivity as a copolymer component in a shell layer having a core / shell structure is used, We found that the objective could be achieved.

  That is, by using a vinyl resin containing 55% by mass or more of methyl methacrylate as a copolymer component in the shell layer of the core / shell structure, the thermal conductivity of the shell layer is increased, and this clear toner particle layer has a glossy It is presumed that when heated using an application device, the resin can be obtained by being softened or melted at high speed to form a clear toner layer having a smooth surface.

  The reason why this clear toner is excellent in heat-resistant storage is that a shell containing a vinyl resin mainly composed of methyl methacrylate having a glass transition point of 45 ° C. or more and 60 ° C. or less on the surface of the clear toner. Since it has a layer, the core portion (for example, styrene-acrylic resin) is less likely to bleed out on the surface of the clear toner particles, and it is assumed that the occurrence of aggregation during storage can be suppressed.

  It is presumed that the reason why the document offset does not occur when the printed materials are superposed is that the surface of the printed material is covered with the above-described vinyl resin having a high glass transition 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 high-gloss printed material having a 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 printed matter using the clear toner of the present invention is not limited as long as it can form an image by a known method and can hold a clear toner layer. It does not specifically limit and 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》
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”.

<Clear toner particle layer>
The “clear toner particle layer” referred to in the present invention is a layer formed with clear toner on the entire surface of the image support, and refers to a layer before gloss treatment. Clear toner particle layer is preferably formed by using the clear toner 2 g / m ² or more 15 g / m ² or less on the image support.

  The clear toner layer formed with the clear toner amount in the above-described range can obtain high gloss. It is also excellent in document offset resistance.

《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 clear toner layer area of the printed matter produced through the gloss applying device shown in FIG. 3 is measured according to “JIS Z8741 1997” at an incident angle of 20 ° with a 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 pulses with a laser, and the thermal diffusivity is obtained from the temperature increase on the back side.

  The thermal conductivity of the resin is measured by emitting laser light from a laser oscillator and directly irradiating the surface of the sample (resin test piece), and measuring the amount of heat and its time coming out 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 composed of a core portion and a shell layer.
2. The core part is preferably formed using a styrene-acrylic resin.
3. The shell layer contains a vinyl resin having a high thermal conductivity (hereinafter also referred to as a specific vinyl resin). The specific vinyl resin in the shell layer contains 55% by mass or more of methyl methacrylate as a copolymerization component, and the content is preferably 55% by mass or more and 95% by mass or less. Moreover, it is preferable that specific vinyl resin contains 5 to 15 mass% of methacrylic acid as a copolymerization component.
4). The glass transition point of the specific vinyl resin is preferably 45 ° C. or higher and 60 ° C. or lower.
5. The weight average molecular weight of the specific vinyl resin is preferably 8,000 or more and 15,000 or less.

  The specific vinyl resin contains methyl methacrylate in an amount of 55% by mass to 95% by mass, so that a printed matter having a uniform glossiness can be produced at high speed using a gloss imparting device. It is preferable because tackiness can be satisfied.

  By using a resin having a glass transition point of 45 ° C. or higher, heat-resistant storage stability and document offset resistance can be satisfied, and by using a resin having a temperature of 60 ° C. or lower, a gloss imparting device is used and prints having uniform glossiness It is preferable because an object can be created at high speed.

<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 layer having a specific vinyl resin.

  The clear toner of the present invention is preferably one in which a shell layer having a thickness of 100 nm or more and 1.0 μm or less is formed on the surface of the core portion having an average circularity of 0.70 or more.

  In the present invention, a clear toner having a structure in which a shell layer is formed using resin particles for a shell layer having a volume-based median diameter of 60 nm or more and 400 nm or less on the surface of the core portion having an average circularity of 0.70 or more is preferable. If shell layer resin particles having a volume-based median diameter of 60 nm or more and 400 nm or less are used, the gap area between the adhered resin particles for the shell layer is reduced on the surface of the core, and a uniform shell layer without unevenness is formed. preferable.

  The volume-based median diameter of the resin particles for the shell layer can be measured in a state where the resin particles are dispersed in the surfactant aqueous 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 layer having a uniform thickness on the surface of the core part as evenly as possible. Therefore, the manufacturing method of the resin particles for the shell layer 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 layer 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.

  The glass transition point of the resin constituting the core part is preferably 25 ° C. or more and 40 ° C. or less, and the weight average molecular weight is preferably 15,000 or more and 25,000 or less. When the glass transition point and the weight average molecular weight are in the above ranges, preferable fixing characteristics can be obtained.

<Average circularity of core>
The average circularity of the core part is preferably 0.70 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,
Average circularity of the core portion = (perimeter of a circle having the same projection area as the core projection image) / (perimeter of the core 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 addition, in this invention, the average circularity of a core part means the value obtained by measuring above.

《Shell layer》
The shell layer contains a specific vinyl resin containing 55% by mass or more of methyl methacrylate as a copolymerization component. The shell layer may contain other resins as necessary.

  The vinyl resin of the shell layer preferably contains 55% by mass to 95% by mass of methyl methacrylate as a copolymerization component. The vinyl resin of the shell layer further preferably contains 5% by mass to 15% by mass of methacrylic acid as a copolymerization component in addition to methyl methacrylate. Further, the vinyl resin constituting the shell layer contains methyl methacrylate and methacrylic acid as copolymerization components, and the glass transition point of the vinyl resin is preferably 45 ° C. or higher and 60 ° C. or lower.

  The thermal conductivity of the vinyl resin of the shell layer increases when it contains 55% by mass or more of methyl methacrylate as a copolymerization component. If it is 55% by mass or less, sufficient thermal conductivity cannot be obtained. Further, the resin constituting the shell layer may contain another vinyl monomer as a copolymerization component.

  Examples of other vinyl monomers used in the shell layer of the present invention include styrene monomers, acrylic acid ester monomers, methacrylic acid ester monomers, and acrylic acid. Specific examples of these monomers include the same monomers as those used for the core portion.

  The weight average molecular weight of the vinyl resin of the shell layer used in the present invention is preferably 8000 or more and 15,000 or less.

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

《Clear toner manufacturing method》
As a preferred production method of the clear toner of the present invention, various production methods can be employed. As an example, a step of agglomerating resin particles to produce a core part, and a shell layer on the surface of the core part A method of preparing a clear toner having a core / shell structure through a step of forming resin layers and forming a shell layer 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 fusing step in which resin particles are agglomerated and fused to produce a core part (hereinafter also referred to as core particle) (4) first ripening step in which the shape is adjusted by aging the core particles with thermal energy (5) Shelling step of adding core layer resin particles to the core particle dispersion and aggregating and fusing the shell layer resin particles on the surface of the core particles 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 Washing step (8) Drying step of drying the washed treated particles (9) drying the treated adding necessary external additives to particles removed by.

  When the clear toner of the present invention is produced, first, resin particles are agglomerated and fused to produce core particles serving as a core. Next, the shell layer resin particles are added to the core particle dispersion, and the shell layer resin particles are aggregated and fused on the surface of the core particles to form a shell layer. Particles having a core / shell structure coated with the above are prepared.

  The clear toner of the present invention preferably has a thin shell layer and a uniform and uniform film thickness, and a clear toner having a uniform and small particle size with a uniform particle size after the shell layer is formed 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 shell layer resin particles 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 that form the shell layer uniformly adhere to the surface thereof, 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 and 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, which will be 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, silicone 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 = 95: 5 to 85:15 by mass ratio.

<How to create printed materials>
<How to create a glossy print>
As a method for producing a glossy printed matter using the clear toner of the present invention, after supplying clear toner to the entire surface of an image support having a toner image produced by an electrophotographic image forming apparatus to form a clear toner particle layer And a method of forming the glossy clear toner layer by heating and pressurizing the clear toner particle layer with a heat and pressure fixing device.

  FIG. 1 shows a method for producing a “glossy printed matter” through a step of forming a clear toner particle layer on an image support having a toner image and a step of forming a glossy clear toner layer by heating and pressing the clear toner particle layer. It is a schematic diagram which shows an example.

  In FIG. 1, P is an image support, T is a toner image, A is a glossy printed matter, B is a clear toner particle layer, C is a glossy clear toner layer, 1p is a clear toner particle layer forming step, and 2p is a glossy clear toner. The formation process of a layer is shown.

  The “glossy printed matter” shown in FIG. 1 is prepared by first forming a toner image T on an image support P using an electrophotographic image forming apparatus, and then forming a clear toner particle layer B on the image support P. After that, the clear toner particle layer B is heated and pressurized through a heat and pressure fixing device to form a glossy clear toner layer C, thereby creating a “glossy printed matter A”.

<How to create a high gloss print>
As a method for producing a “high gloss print” using the clear toner of the present invention, the gloss print having the gloss clear toner layer produced above is heated and pressed by a high gloss applicator to obtain a high gloss clear toner layer. And forming a “high gloss print”.

  FIG. 2 is a schematic diagram showing an example of a method for creating a “high gloss printed matter” through a high gloss applying device from a “gloss printed matter” having a gloss clear toner layer.

  In FIG. 2, P is an image support, T is a toner image, A is a glossy printed product, C is a glossy clear toner layer, D is a high gloss clear toner layer, E is a “high gloss print”, and 3p is a high gloss clear A toner layer forming step will be described.

  In the method of creating the “high gloss print” shown in FIG. 2, the “gloss print A” having the gloss clear toner layer C is passed through the high gloss applicator, and the gloss clear toner layer surface is heated and pressurized, and then cooled and peeled off. Thus, a high gloss clear toner layer D is formed to create a “high gloss print E”.

  FIG. 3 is a schematic diagram showing an example of a high gloss applying device capable of creating a high gloss printed matter.

  In the high gloss applicator, it is preferable to use a high gloss applicator that does not have a means for applying the silicone oil because the glossiness decreases when the silicone oil is applied to the heating roll or the heating belt.

  In FIG. 3, P is an image support, T is a toner image, C is a glossy clear toner layer, D is a high gloss clear toner layer, E is a “high gloss print”, 1 is a high gloss applicator, and 10a is heated. Pressure part, 11a is a heating roll, 12a is a pressure roll, 13 is a heating source, 14a is a pressure spring, 20a is a cooling and conveying part, 21a is a belt, 22a is a cooling fan, 23a is cold air, 24a is a conveying roll, 25a Is the separation roll, 30a is the direction in which the printed material is conveyed, T1 is the surface temperature of the belt immediately before the image support is nipped by the heating and pressing unit, and T2 is the position where the image support is discharged from the conveyance belt and the separation belt. Indicates the temperature of the high gloss clear toner layer surface.

  The high gloss applying device 1 shown in FIG. 3 includes a heating and pressing unit 10a and a cooling and conveying unit 20a. In the heating and pressing unit, the “glossy printed matter A” is sandwiched and conveyed between the heating roll 11a and the pressing roll 12a that are driven at a constant speed, and the conveyed glossy clear toner layer C is heated and pressurized. It is. That is, the glossy clear toner layer C formed on the image support P is heated and pressurized to melt and then cooled to form a high gloss clear toner layer D, and a “high gloss print E” is obtained. .

  The heating roll 11a includes a heating source 13 and the pressure roll 12a includes a pressure spring 14a. It should be noted that the heating source 13 may be incorporated in the pressure roll 12a.

  The width of the nip portion between the heating roll and the pressure roll is preferably about 2 to 18 mm, and more preferably about 9 to 15 mm.

  The surface pressure of the nip portion between the heating roll and the pressure roll is desirably 100 to 1000 kPa.

  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. For example, a 300 to 350 W halogen lamp is disposed inside the heating roll as a heating source, and the heating roll is heated from the inside so that the surface temperature of the heating roll becomes a target temperature.

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

  Next, the cooling conveyance unit 20a will be described. The cooling and conveying unit 20a includes an endless belt 21a and a cooling unit 22a that are rotatably supported by a heating roll 11a and a plurality of rolls 24a.

  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 has a certain degree of heat resistance and mechanical strength. Consists of a film and a release layer. Examples of the heat-resistant film resin include polyimide, polyether polyimide, PES (polyether sulfone resin), and PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin). As releasability, it is preferable to provide a fluororesin such as PTFE (polytetrafluoroethylene) or PFA, or silicone rubber.

  The thickness of the belt is not particularly limited as long as the image support P can be conveyed through an adhesive surface with the melted clear toner layer surface, and a belt having a known thickness can be used. . For example, 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 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 22a 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 and conveyed on the belt 21a 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 25a is disposed, and the high gloss printed matter E is peeled off from the belt at the end.

  FIG. 4 shows an electronic device in which a clear toner particle layer is formed on the entire surface of an image support simultaneously with the creation of a color toner image, and then a glossy clear toner layer can be formed through a heat and pressure fixing device. 1 is a schematic diagram illustrating an example of a photographic image forming apparatus.

  The electrophotographic image forming apparatus 2 shown in FIG. 4 is generally called a “tandem color image forming apparatus”, and includes a clear toner particle layer forming unit 20S and a plurality of sets of toner image forming units 20Y, 20M, 20C, 20Bk, The belt-shaped intermediate transfer belt 26, a paper feeding device 40, a heating and pressure fixing device 50, and the like are included.

  An image reading unit 23 is installed on the electrophotographic 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 23 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 electrophotographic image forming apparatus 2 in FIG. 4 includes a clear toner particle layer forming unit 20S that forms a clear toner particle layer on the entire surface of an image support via an intermediate transfer belt 26, and a yellow image forming that forms a yellow toner image. A unit 20Y, 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 a 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. 4, 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 24 is composed of two components each composed of a toner of different colors and a carrier of clear toner (S), yellow toner (Y), magenta toner (M), cyan toner (C) and black toner (Bk) according to the present invention. It contains developer.

The intermediate transfer belt 26 that is an intermediate transfer member is rotatably supported by a plurality of rollers. The intermediate transfer belt 26 is, for example, an endless bell having a volume resistance of 10 ⁶ to 10 ¹² Ω · cm. The intermediate transfer belt 26 is made of a known resin material such as polycarbonate (PC), polyimide (PI), polyamideimide (PAI), polyvinylidene fluoride (PVDF), or tetrafluoroethylene-ethylene copolymer (ETFE). Can be formed. 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 electrophotographic 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 between the heating roll and the pressure roll of the heating and pressure fixing device 50, and the clear toner and each toner are melted and solidified by the action of heating and pressing. To do. In this manner, the heat and pressure 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. 5 is a schematic diagram showing an example of an apparatus in which a high gloss applying device is attached to the electrophotographic image forming apparatus of FIG.

  In FIG. 5, the high gloss applying device 1 of FIG. 3 is arranged at the location of the paper discharge unit 90 of the electrophotographic image forming apparatus 2 of FIG. 4, and the heating process incorporated in the electrophotographic image forming apparatus 2 of FIG. The image support P having the glossy clear toner layer fixed by the pressure fixing device 50 is subjected to high gloss processing of the glossy clear toner layer through the high gloss applicator 1.

  FIG. 6 is a schematic view showing an example of an apparatus in which a high gloss applying device is attached instead of the heat and pressure fixing device of the electrophotographic image forming apparatus 2 shown in FIG.

  In FIG. 6, the high gloss applying device 1 of FIG. 3 is attached in place of the heat and pressure fixing device 50 of the electrophotographic image forming apparatus 2 shown in FIG. 4, and the secondary transfer roller 29 is placed on the image support P. A high gloss clear toner layer can be formed on the transferred clear toner particle layer by the high gloss applicator 1. According to the apparatus shown in FIG. 6, the high gloss applying apparatus 1 can take a form incorporated in the electrophotographic image forming apparatus 2, which is preferable for realizing a compact apparatus.

  A high-gloss printed matter produced using clear toner can be used for applications that require high gloss and for surface durability. In particular, it is preferably used for applications such as outdoor posters.

  Hereinafter, modes for carrying out the present invention will be described in detail, but embodiments of the present invention are not limited thereto.

(Example 1: Preparation of clear toner particles 1)
<Preparation of core part resin particle dispersion A1>
(First stage polymerization)
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction device,
Surfactant (Polyoxyethylene-2-dodecyl ether sodium sulfate)
12 parts by weight ion-exchanged water charged with 1185 parts by weight of the solution, heated to 82 ° C.,
Styrene 218 parts by weight n-butyl acrylate 97 parts by weight Methacrylic acid 18 parts by weight Chain transfer agent (n-octyl mercaptan) 6.4 parts by weight Wax (paraffin wax) Polymerizable monomer obtained by dissolving 180 parts by weight at 80 ° C. The body solution was added and mixed and dispersed for 1 hour by a mechanical disperser “CREARMIX (manufactured by M Technique Co., Ltd.) having a circulation path to prepare a dispersion containing emulsified particles (oil droplets).

The dispersion is then
Polymerization is carried out by adding an initiator solution in which 12 parts by mass of a polymerization initiator (potassium persulfate) is dissolved in 230 parts by mass of ion-exchanged water, and the system is heated and stirred at 82 ° C. for 1 hour to obtain resin particles. Dispersion 1 was prepared.

(Second stage polymerization)
A solution prepared by dissolving 10 parts by mass of a polymerization initiator (potassium persulfate) in 220 parts by mass of ion-exchanged water was added to the resin particle dispersion 1, and the temperature was 82 ° C.
Styrene 393 parts by mass n-butyl acrylate 147 parts by mass Chain transfer agent (n-octyl mercaptan) A polymerizable monomer solution consisting of 7.0 parts by mass was added dropwise over 1.5 hours.

  After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain a resin particle dispersion A1 for core part.

<Preparation of resin particle dispersion B1 for shell layer>
In a reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device, a surfactant solution in which 2.1 parts by mass of surfactant (sodium dodecyl ether sulfate) was dissolved in 2770 parts by mass of ion-exchanged water was charged. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.

In this surfactant solution,
A polymerization initiator (potassium persulfate: KPS) 10 parts by mass was added to an initiator solution prepared by dissolving 400 parts by mass of ion-exchanged water.
Methyl methacrylate 496 parts by weight n-butyl acrylate 208 parts by weight Methacrylic acid 96 parts by weight n-octyl mercaptan 23 parts by weight of a monomer mixture was dropped over 3 hours, and the system was added at 80 ° C for 1 hour. Polymerization was carried out by heating and stirring to obtain a resin particle dispersion B1 for shell layer. The weight average molecular weight of resin particle B1 for shell layers was 11,000, and Tg was 52 degreeC.

(Formation of core particles)
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction device,
Resin particle dispersion A1 for core part (solid content conversion) 415 parts by mass Surfactant (polyoxyethylene-2-dodecyl ether sodium sulfate)
7.6 parts by mass Ion-exchanged water 1020 parts by mass were prepared and the liquid temperature was adjusted to 25 ° C., and then 25% by mass aqueous sodium hydroxide solution was added to adjust the pH to 10.

Then
An aqueous solution in which 70 parts by mass of magnesium chloride was dissolved in 70 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 temperature was raised to 88 ° C., and the particle growth reaction was continued while maintaining 88 ° C. In this state, the particle size of the aggregated particles is measured with “Coulter Multisizer 3”. When the particle size reaches a desired particle size, an aqueous solution in which 7.3 parts by mass of sodium chloride is dissolved in 29 parts by mass of ion-exchanged water is used. Addition to stop particle growth to form core particles.

(Formation of shell layer)
Next, the mixture was superheated at a liquid temperature of 88 ° C. and aged until the circularity reached 0.910 as measured by “FPIA-2100”. The resin particle dispersion B1 for shell layer was 46 parts by mass in terms of solid content. Was added to the system 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 65.7 parts by mass of sodium chloride is dissolved in 263 parts by mass of ion-exchanged water is added to the shell. And then proceeding with the fusion between the particles until the average circularity is 0.960 as measured by “FPIA-2100” by stirring at a liquid temperature of 88 ° C. as an aging step. Toner particles were formed, then cooled to a liquid temperature of 30 ° C., hydrochloric acid was added to adjust the pH to 2.0, and stirring was stopped.

  The toner particles generated in the above process are solid-liquid separated with a basket-type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a toner particle wet cake. 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.). Drying to 0% by mass gave clear toner particles 1 of Example 1.

(Example 2: Production of clear toner particles 2)
<Preparation of resin particle dispersion B2 for shell layer>
In the resin particle dispersion B1 for shell layer, the resin particle dispersion B1 for shell layer was changed except that the charged amounts of methyl methacrylate, n-butyl acrylate and methacrylic acid were changed to 571 parts, 188 parts and 40 parts, respectively. In the same manner, a resin particle dispersion B2 for shell layer was produced.

  Clear toner particles 2 of Example 2 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B2 in the preparation of the clear toner particles 1.

(Example 3: Production of clear toner particles 3)
<Preparation of resin particle dispersion B3 for shell layer>
Resin particle dispersion B1 for shell layer, except that the charged amount of methyl methacrylate, n-butyl acrylate and methacrylic acid was changed to 560 parts by mass, 192 parts by mass and 48 parts by mass, respectively. In the same manner, a resin particle dispersion B3 for shell layer was produced.

  The clear toner particles 3 of Example 3 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B3 in the preparation of the clear toner particles 1.

(Example 4: Production of clear toner particles 4)
<Preparation of resin particle dispersion B4 for shell layer>
In the resin particle dispersion B1 for shell layer, the resin particle dispersion B1 for shell layer was changed except that the charged amounts of methyl methacrylate, n-butyl acrylate and methacrylic acid were changed to 464 parts by mass, 216 parts by mass and 120 parts by mass, respectively. In the same manner, a resin particle dispersion B4 for shell layer was produced.

  The clear toner particles 4 of Example 4 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B4.

Example 5 Production of Clear Toner Particle 5
<Preparation of resin particle dispersion B5 for shell layer>
In the resin particle dispersion B1 for shell layer, the resin particle dispersion B1 for shell layer was changed except that the charged amounts of methyl methacrylate, n-butyl acrylate and methacrylic acid were changed to 452 parts by mass, 220 parts by mass and 128 parts by mass, respectively. In the same manner, a resin particle dispersion B5 for shell layer was produced.

  The clear toner particles 5 of Example 5 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B5.

Example 6 Production of Clear Toner Particle 6
<Preparation of resin particle dispersion B6 for shell layer>
Resin particle dispersion B1 for shell layer, except that in the resin particle dispersion B1 for shell layer, the amounts of methyl methacrylate, n-butyl acrylate and methacrylic acid were changed to 460 parts by mass, 243 parts by mass and 96 parts by mass, respectively. In the same manner, a resin particle dispersion B6 for shell layer was produced.

  Clear toner particles 6 of Example 6 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B6 in the preparation of the clear toner particles 1.

Example 7 Production of Clear Toner Particle 7
<Preparation of resin particle dispersion B7 for shell layer>
In the resin particle dispersion B1 for shell layer, the resin particle dispersion B1 for shell layer was changed except that the charged amounts of methyl methacrylate, n-butyl acrylate and methacrylic acid were changed to 470 parts by mass, 234 parts by mass and 96 parts by mass, respectively. In the same manner, a resin particle dispersion B7 for shell layer was produced.

  The clear toner particles 1 of Example 7 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B7.

Example 8 Production of Clear Toner Particle 8
<Preparation of resin particle dispersion B8 for shell layer>
In the resin particle dispersion B1 for shell layer, the resin particle dispersion B1 for shell layer was changed except that the charged amounts of methyl methacrylate, n-butyl acrylate and methacrylic acid were changed to 524 parts by mass, 180 parts by mass and 96 parts by mass, respectively. In the same manner, a resin particle dispersion B8 for shell layer was produced.

  Clear toner particles 8 of Example 8 were produced in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B4 in the production of the clear toner particles 1.

Example 9 Production of Clear Toner Particle 9
<Preparation of resin particle dispersion B9 for shell layer>
Resin particle dispersion B1 for shell layer, except that the charged amount of methyl methacrylate, n-butyl acrylate, and methacrylic acid was changed to 533 parts, 171 parts, and 96 parts by weight, respectively. In the same manner, a resin particle dispersion B9 for shell layer was produced.

  Clear toner particles 9 of Example 9 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B9 in the preparation of the clear toner particles 1.

Example 10 Production of Clear Toner Particle 10
<Preparation of resin particle dispersion B10 for shell layer>
In the shell layer resin particle dispersion B1, the shell layer resin particle dispersion B10 was prepared in the same manner as in the shell layer resin particle dispersion B1, except that the amount of n-octyl mercaptan charged was changed to 39.5 parts by mass. Produced.

  Clear toner particles 10 of Example 10 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B10 in the production of the clear toner particles 1.

Example 11 Production of Clear Toner Particle 11
<Preparation of resin particle dispersion B11 for shell layer>
In the shell layer resin particle dispersion B1, the shell layer resin particle dispersion B11 was prepared in the same manner as in the shell layer resin particle dispersion B1, except that the amount of n-octyl mercaptan charged was changed to 33.8 parts by mass. Produced.

  The clear toner particles 11 of Example 11 were produced in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B10 in the production of the clear toner particles 1.

Example 12 Production of Clear Toner Particles 12
<Preparation of resin particle dispersion B12 for shell layer>
In the shell layer resin particle dispersion B1, the shell layer resin particle dispersion B12 was prepared in the same manner as in the shell layer resin particle dispersion B1, except that the amount of n-octyl mercaptan charged was changed to 18.6 parts by mass. Produced.

  Clear toner particles 12 of Example 12 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B12 in the production of the clear toner particles 1.

Example 13 Production of Clear Toner Particles 13
<Preparation of resin particle dispersion B13 for shell layer>
Resin particle dispersion B13 for shell layer was prepared in the same manner as resin particle dispersion B1 for shell layer, except that the amount of n-octyl mercaptan charged in shell layer resin particle dispersion B1 was changed to 14 parts by mass. .

  Clear toner particles 13 of Example 13 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B13 in the production of the clear toner particles 1.

(Comparative Example 1: Preparation of clear toner particles 14)
<Preparation of resin particle dispersion B14 for shell layer>
In the resin particle dispersion B1 for shell layer, the resin particle dispersion B1 for shell layer was changed except that the charged amounts of methyl methacrylate, n-butyl acrylate and methacrylic acid were changed to 435 parts by mass, 244 parts by mass and 120 parts by mass, respectively. In the same manner, a resin particle dispersion B14 for shell layer was produced.

  The clear toner particles 14 of Comparative Example 1 were prepared in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B14.

(Comparative Example 2: Preparation of clear toner particles 15)
<Preparation of resin particle dispersion B15 for shell layer>
In the resin particle dispersion B1 for shell layer, except that the amounts of styrene, n-butyl acrylate and methacrylic acid were changed to 530 parts by mass, 173 parts by mass and 96 parts by mass, respectively, Similarly, a shell layer resin particle dispersion B15 was produced.

  A clear toner 15 of Comparative Example 2 was produced in the same manner as the clear toner particles 1 except that the shell resin particle dispersion B1 was changed to the shell resin particle dispersion B15 in the production of the clear toner particles 1.

(Comparative Example 3: Preparation of clear toner particles 16)
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction device,
Resin particle dispersion A1 for core part (solid content conversion) 461 parts by mass Surfactant (polyoxyethylene-2-dodecyl ether sodium sulfate)
7.6 parts by mass Ion-exchanged water 1020 parts by mass were prepared and the liquid temperature was adjusted to 25 ° C., and then 25% by mass aqueous sodium hydroxide solution was added to adjust the pH to 10.

Then
An aqueous solution in which 70 parts by mass of magnesium chloride was dissolved in 70 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 temperature was raised to 88 ° C., and the particle growth reaction was continued while maintaining 88 ° C. In this state, the particle size of the aggregated particles is measured with “Coulter Multisizer 3”, and when the particle size reaches a desired particle size, an aqueous solution in which 36.0 parts by mass of sodium chloride is dissolved in 328 parts by mass of ion-exchanged water is used. Add to stop grain growth.

  Next, the mixture is heated and stirred at a liquid temperature of 88 ° C., and toner particles are formed while fusing the particles until the circularity becomes 0.960 as measured by “FPIA-2100”. The mixture was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 2.0, and stirring was stopped.

  The toner particles produced in the above process are solid-liquid separated with a basket-type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a wet cake of toner particles. 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.). Drying to 0% by mass gave clear toner particles 16 having no core / shell structure.

(External additive mixing: preparation of clear toners [1] to [16])
The following external additives are added to 100 parts by mass of each of clear toner particles 1 to 16 produced as described above, and the peripheral speed of the stirring blade is 35 m / sec by “Henschel mixer” (manufactured by Mitsui Miike Mining Co., Ltd.). An external addition process was performed under conditions of a processing temperature of 35 ° C. and a processing time of 8 minutes to prepare clear toner [1] to clear toner [16].
-0.4 part by mass of silica treated with hexamethyldisilazane (average primary particle size 12 nm)-0.8 part by mass of titanium dioxide treated with n-octylsilane (average primary particle size 24 nm)

<Evaluation>
(Development of developer)
The clear toners [1] to [16] prepared as described above were mixed with 93 parts by mass of a ferrite carrier having a volume average particle size of 50 μm coated with a silicone resin to prepare a two-component developer. It used for evaluation.

  The apparatus shown in FIG. 5 was set under the following conditions, and the developer 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 with an outer diameter of 100 mm and a thickness of 10 mm provided with a 3 mm thick silicone rubber layer-Pressurizing roll: 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 an aluminum substrate. A halogen lamp is disposed inside the heating roll. The surface temperature of the heating roll is 180 ° C., and the surface temperature of the pressure roll is 80 ° C. Setting (temperature control by thermistor)
・ Nip width between heating roll and pressure roll: 9mm
(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: 135 mm / second (h) Image support conveyance direction: A4 size of the above 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 document offset resistance)
Using the fixed image created at the time of the gloss evaluation, the image portion, the non-image portion, and the image portion are overlapped with each other so that they overlap each other, and the overlapped portion corresponds to 80 g / cm ^2. A weight was placed and left in a high-temperature and high-humidity tank at 60 ° C. and 50% humidity for 7 days. The degree of image defects of the two fixed images superimposed after standing is shown below.

Evaluation Criteria 5: Image transition is not seen at all in the image portion and the non-image portion.

  4: When the two superimposed images are separated, a crisp sound is heard, and a slight image transfer is seen in the minute gloss-enhanced portion non-image portion in the fixed image portion, but there is no image defect and no problem at all.

  3: When separating the two superimposed images, the fixed images of each other cause image blurring or gloss reduction.

  2: Since the two printed sheets are adhered to each other, white spots of image defects occur in some places in the image area, or the paper surface of the non-fixed area adheres to the image area.

  1: The two printed sheets that are stacked do not peel off because they are adhered, and if they are forcibly removed, the entire surface of the paper is peeled off, resulting in severe image defects.

(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 the results in Table 2, it is understood that “Examples 1 to 13” using the clear toners [1] to [13] 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 comparative clear toners [14] to [16] are inferior in 20 ° glossiness.

1p Clear toner particle layer formation process 2p Glossy clear toner layer formation process 3p High gloss clear toner layer formation process P Image support A Glossy printed matter B Clear toner particle layer C Glossy clear toner layer D High gloss clear toner layer E High gloss printed matter T Toner image 21S, 21Y, 21M, 21C, 21Bk Photoconductor 22S, 22Y, 22M, 22C, 22Bk Band electrode 30S, 30Y, 30M, 30C, 30Bk Exposed area 24S, 24Y, 24M, 24C, 24Bk Development Equipment 25S, 25Y, 25M, 25C, 25Bk Cleaning device

Claims (6)

In a clear toner having a core-shell structure having a shell layer on the surface of the core portion, the resin constituting the shell layer is a vinyl resin, and the vinyl resin is a copolymer component and methyl methacrylate is used as a copolymerization component. A clear toner comprising 55% by mass to 95% by mass and containing 5% by mass to 15% by mass of methacrylic acid, and the resin constituting the core part is a styrene-acrylic resin. . The clear toner according to claim 1 , wherein a glass transition point of the vinyl resin constituting the shell layer is 45 ° C. or more and 60 ° C. or less. Clear toner according to claim 1 or 2 weight-average molecular weight of the vinyl resin constituting the shell layer is characterized in that 8,000 or more to 15,000 or less. Clear toner according to any one of claims 1 to 3, a glass transition point of the resin constituting the core portion and wherein the at 40 ° C. or less 25 ° C. or higher. The clear toner according to any one of claims 1 to 4 , wherein the resin constituting the core portion has a weight average molecular weight of 15,000 or more and 25,000 or less. At least a step of supplying a clear toner on the image support to create a print image having a clear toner particle layer, and heating and pressurizing the surface of the clear toner particle layer of the print image to form a clear toner layer; In the image forming method for producing a printed matter through the step of cooling the clear toner layer in close contact with the toner, the clear toner used in the image forming method has a shell layer on the surface of the core portion. The resin having a core-shell structure and constituting the shell layer is a vinyl resin, the vinyl resin contains 55% by mass to 95% by mass of methyl methacrylate as a copolymerization component, 5 and those containing by mass% to 15 mass%, the resin constituting the core portion is a styrene - imaging side, characterized in that the acrylic resin .

Images