JP2010210703A - Developer for electrostatic charge image development, and gloss imparting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer for electrostatic charge image development and a gloss imparting device, which imparts gloss to a color toner image and forms an image of high picture quality while suppressing dullness in colors of the color toner image or generation of an image void. <P>SOLUTION: The developer contains a carrier and a transparent toner, wherein the carrier includes a core material and a coating layer containing at least a crystalline polyester resin (A) and an amorphous resin (B), and has a volume resistivity upon compression, ranging from 1.0×10<SP>9</SP>Ω cm to 1.0×10<SP>14</SP>Ω cm when an electric field expressed by logE=4.0 V/cm is applied. The gloss imparting device uses the above developer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developer and a gloss imparting device.

  A method of visualizing image information through an electrostatic latent image by electrophotography or the like is currently used in various fields. In electrophotography, image information is formed as an electrostatic latent image on the surface of a latent image carrier (photoreceptor) by charging and exposure processes, and the toner image is developed on the surface of the photoreceptor using a developer containing toner. The toner image is visualized as an image through a transfer step of transferring the toner image to a recording medium (transfer object) such as paper and a fixing step of fixing the toner image on the surface of the recording medium.

In recent years, color image formation by color electrophotography, which has been remarkably popular, generally uses four color toners, including three subtractive primary colors, yellow, magenta, and cyan, and black toner. It is a reproduction.
In general color electrophotography, first, an original (image information) is color-separated into yellow, magenta, cyan, and black, and an electrostatic latent image is formed on the surface of the photoreceptor for each color. At this time, the electrostatic latent image formed for each color is developed using a developer containing toner of each color to form a toner image, and the toner image is transferred to the surface of the recording medium through a transfer process. A series of steps from the formation of the electrostatic latent image to the transfer of the toner image to the surface of the recording medium is sequentially performed for each color, and the toner image of each color is superimposed on the surface of the recording medium so as to match the image information. Transcribed. In the transfer step, the toner image is transferred to the recording medium via the intermediate transfer member, or the toner image is directly transferred to the recording medium.
The color toner image obtained by transferring the color toner images onto the surface of the recording medium in this manner is fixed as a color image through a fixing step.

These color images have a certain degree of gloss because the surface is smoothed during heat fixing, whereas the surface of the paper usually does not have a gloss. It has a glossiness different from that of the paper surface.
By forming a transparent toner image made of a binder resin having specific properties on the color toner image formed on the recording medium, the level difference between the recording medium surface and the color toner image is eliminated, and a uniform image with high gloss is obtained. An obtaining method has been proposed (see, for example, Patent Document 1).
In addition, in order to control charging of a carrier used for a developer, a technique for dispersing a conductive substance in a resin coating layer has been proposed (see, for example, Patent Documents 2 to 4).

JP-A-2005-99122 JP-A-6-148952 JP 10-333363 A Japanese Patent No. 2998633

  The present invention relates to a transparent developer capable of imparting gloss to a color toner image and forming a high-quality image while suppressing occurrence of color dullness and image omission in a color toner image, and an image gloss imparting apparatus using the same The purpose is to provide.

That is, the invention according to claim 1 contains a carrier and a transparent toner, and the carrier has a core material and a coating layer containing at least a crystalline polyester resin A and an amorphous resin B, and is compressed. The electrostatic charge image developing developer has a volume resistance of 1.0 × 10 ⁹ Ω · cm to 1.0 × 10 ¹⁴ Ω · cm when an electric field of log E = 4.0 V / cm is applied.

In the invention according to claim 2, the endothermic peak temperature derived from the crystalline polyester resin A contained in the coating layer of the carrier is TmA (° C.), and the crystallinity in the mixture of the crystalline polyester resin A and the amorphous resin B is The electrostatic charge image developing developer according to claim 1, wherein when the endothermic peak temperature derived from the polyester resin is TmAB (° C.), TmA (° C.) and TmAB (° C.) satisfy the relationship of the following formula (1).
5 <TmA-TmAB <20 (1)

  In the invention according to claim 3, the mixing ratio (A / B) of the crystalline polyester resin A and the amorphous resin B contained in the coating layer of the carrier is in the range of 1/99 to 40/60 in terms of mass. The developer for developing an electrostatic image according to claim 1, wherein the developer is an electrostatic charge image developing agent.

  The invention according to claim 4 is the electrostatic charge image developing according to any one of claims 1 to 3, wherein the coating layer of the carrier contains crosslinked resin particles that impart a negative chargeability to the transparent toner. Developer.

  In the invention according to claim 5, the endothermic peak temperature [TmA (° C.)] derived from the crystalline polyester resin A contained in the carrier coating layer is 50 ° C. or more and 150 ° C. or less. The developer for developing an electrostatic image according to any one of the above items.

  According to a sixth aspect of the present invention, after a color toner image is formed on the surface of a recording medium by an electrophotographic method using a color toner containing a thermoplastic resin and a colorant, the color toner image is formed around the color toner image. A gloss imparting device that imparts gloss to an image by transferring and fixing the developer for developing an electrostatic charge image according to any one of Items 5 and a transparent toner image holding body that holds a transparent toner image; A transparent toner image forming means for forming a transparent toner image comprising the developer for developing an electrostatic image according to any one of claims 1 to 5 on the surface of the transparent toner image holding member, and the transparent toner image The transparent toner image formed on the surface of the holding member is transferred to the surface of the recording medium surface on which the color toner image is formed, and is heated and pressed to be fixed by heating and pressing, and transferred to the surface of the recording medium. Settled After cooling the transparent toner image and the color toner image, a gloss providing device comprising a transparent toner image and the recording medium on which the color toner image has been formed, a cooling peeling means for peeling the transparent toner image holding body.

  According to the first aspect of the present invention, as compared with the case where the present configuration is not provided, the color toner image is given a gloss while suppressing the occurrence of color dullness and image omission in the color toner image, and a high-quality image. Is formed.

  According to the second aspect of the present invention, as compared with the case where the present configuration is not provided, the color toner image is given glossiness while suppressing the occurrence of color dullness and image omission in the color toner image, and a high-quality image. Is formed.

  According to the third aspect of the present invention, compared with the case where the mixing ratio is outside this range, color dullness and image loss of the color toner image are suppressed, and the gloss imparted to the color toner image is improved. The

  According to the fourth aspect of the present invention, the effect of suppressing the occurrence of image omission at the edge of the color toner image is further sustained in the long-term use of the developer as compared with the case where no crosslinked resin particles are contained.

  According to the invention of claim 5, the gloss imparted to the color toner image is improved as compared with the case where the endothermic peak temperature is outside this range.

  According to the sixth aspect of the present invention, compared to the case without the present configuration, the gloss imparting that imparts a good gloss to the color toner image while suppressing the occurrence of color dullness and image omission in the color toner image. Get the device.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus including a gloss providing device according to an embodiment. FIG. 4 is a schematic cross-sectional view illustrating a state between a transparent toner image holding member and a recording medium when passing through a pressure contact portion between a heating roll and a pressure roll in the gloss applying apparatus according to the present embodiment.

  Hereinafter, embodiments of the developer and gloss imparting apparatus of the present invention will be described in detail.

<Developer>
The developer for developing an electrostatic charge image according to this embodiment has a transparent toner, a core material, and a coating layer containing at least a crystalline polyester resin A and an amorphous resin B, and has a volume resistance during compression. , LogE = 4.0 V / cm, and a carrier that is 1.0 × 10 ⁹ Ω · cm or more and 1.0 × 10 ¹⁴ Ω · cm or less when an electric field is applied.

[The core material and a coating layer containing at least the crystalline polyester resin A and the amorphous resin B have a volume resistance at the time of compression of 1.0 × 10 × 10 when an electric field of log E = 4.0 V / cm is applied. Carriers that are ⁹ Ω · cm or more and 1.0 × 10 ¹⁴ Ω · cm or less]
In general, in a crystalline polyester resin having a low crystallinity and a relatively low melting point, an amorphous part of the crystalline resin has a glass transition temperature in a room temperature range (25 ° C.) or lower, and the glass Above the transition temperature, this amorphous part has a molecular chain segmental motion, and there is a problem that the movement of this molecule prevents charge retention and the electrical resistance of the crystalline resin itself is low, in this embodiment, By having the mixture of the crystalline polyester resin A and the amorphous resin B as a coating layer, the carrier and developer resistance are adjusted.
At this time, the compatibility with the amorphous resin B is controlled, and the volume resistance at the time of compression is controlled within the range defined by the present embodiment, so that the carrier and developer resistance are adjusted, and the image omission is effectively prevented. It has been suppressed to.

Regarding the compatibility in the mixture of the crystalline polyester resin A and the amorphous resin B, when both are excessively compatible, the glass transition temperature is lowered by the compatibilization, the resin strength is lowered, or the developer Where there is a concern that the fluidity may be lowered, attention was paid to fluctuations in the endothermic peak temperature derived from the crystalline polyester resin A as an indication of compatibility. That is, the endothermic peak temperature derived from the crystalline polyester resin A is defined as TmA (° C.), and the endothermic peak temperature derived from the crystalline polyester resin A when the crystalline polyester resin A and the amorphous resin B are mixed is expressed as TmAB (° C.). In this case, by setting the relationship between the two in a certain range as defined in claim 2, a coating resin layer of a carrier that suppresses excessive compatibility and does not undergo phase separation and does not vary in thickness is generated. .
As a result, carrier resistance is maintained for a longer period of time, there is no color dullness for a long period of time, image loss at the edge of the colored solid image part is suppressed, and a high-quality image of a glossy silver salt photographic tone is obtained.

The carrier in the present embodiment has a volume resistance during compression of 1.0 × 10 ⁹ Ω · cm or more and 1.0 × 10 ¹⁴ Ω · cm or less when an electric field of log E = 4.0 V / cm is applied. Cost. If it is less than 1.0 × 10 ⁹ Ω · cm, it is difficult to suppress carrier adhesion for a long time, and if it exceeds 1.0 × 10 ¹⁴ Ω · cm, the edge effect appears strongly and the development density of the solid image The problem that developability is impaired, such as a fall, occurs. A more preferable range of the volume resistance is 1.0 × 10 ⁹ Ω · cm or more and 1.0 × 10 ¹⁴ Ω · cm or less.

The volume resistance (Ω · cm) of the carrier is measured as follows. The measurement environment is a temperature of 20 ° C. and a humidity of 50% RH.
The object to be measured is placed flat on the surface of a circular jig having a 20 cm ² electrode plate so as to have a thickness of about 1 mm to 3 mm to form a layer. The same 20 cm ² electrode plate as above is placed on this, and the layers are sandwiched. In order to eliminate gaps between objects to be measured, the thickness (cm) of the layer is measured after applying a load of 4 kg on the electrode plate arranged on the layer. Both electrodes above and below the layer are connected to an electrometer and a high voltage power generator. A voltage is applied so that the electric field is log E = 4.0 V / cm to both electrodes, and the volume electric resistance (Ω · cm) of the measurement object is calculated by reading the current value (A) flowing at this time. . The calculation formula of the volume electrical resistance (Ω · cm) of the measurement object is as shown in the following formula (α).
Formula (α) R = E × 20 / (I−I ₀ ) / L

In the above formula (in α, R is the volume electrical resistance (Ω · cm) of the measurement object, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at the applied voltage of 0 V, L represents the thickness (cm) of the layer, and the coefficient of 20 represents the area (cm ² ) of the electrode plate.

-Coating layer-
As described above, the coating layer (hereinafter referred to as the coating resin layer) in the carrier of the present embodiment contains the crystalline polyester resin A and the amorphous resin B, and more preferably, the crosslinked resin particles are coated with the coating resin. Include in the layer.
In the coating layer of the electrostatic charge image developing carrier, the crystalline polyester resin A has an amorphous portion of the crystalline resin that has a glass transition temperature in the normal temperature range (25 ° C.) or lower, and the glass transition temperature or higher. In this case, the amorphous part has a segmental movement of the molecular chain, and the movement of the molecule prevents charge retention, so that the electrical resistance of the resin itself is generally kept low. However, in this embodiment, by mixing the amorphous resin B, both are in an appropriate compatible state, and the low resin strength in the crystalline polyester resin A is eliminated by the compatibilization, which is sufficient for the coating resin layer. It is presumed that a sufficient strength can be imparted, charge retention is improved, and a suitable ability to impart chargeability is imparted. For this reason, there is no dispersion | variation in the coating resin layer intensity | strength of a carrier, and the charging property required for a carrier is maintained.

On the other hand, the phenomenon of change in charge amount when a crystalline resin is used is estimated as follows.
Generally, a crystalline resin tends to have a low resin resistance due to its crystal structure. When a toner is produced using a crystalline resin, regions where the crystalline resin is localized are scattered inside the toner particles regardless of a production method such as a dry production method such as a kneading pulverization method or a wet production method such as an emulsion aggregation method. It is conceivable that a region where the crystalline resin is localized between the toner particles is in point contact with each other to form a charging conduction path and leak the charge. In particular, the amount of change in charge is large under high temperature and high humidity. Water molecules adhere to the surface of toner particles, and not only point contact with a crystalline resin but also water molecules come into contact with each other, and charge is leaked as if by surface contact. This phenomenon occurs in the same manner even in a toner that does not use a crystalline resin, but is more remarkable when a crystalline resin is used. This is because the crystalline resin has a characteristic of easily absorbing moisture. As a result, it is considered that the decrease in charge after standing is increased due to the low resin resistance derived from the crystal structure and the high hygroscopicity.
For this reason, in order for the carrier of this embodiment to achieve the above-mentioned volume resistance and the covering resin layer to achieve sufficient strength, the phase of the crystalline polyester resin A and the amorphous resin B as will be described later. It is important to control solubility.

  In the present specification, the “crystalline resin” refers to a resin having a clear endothermic peak rather than a stepwise endothermic amount change in differential scanning calorimetry (DSC). Specifically, a resin whose half-value width of the endothermic peak when measured at a temperature rising rate of 10 ° C./min is within 6 ° C. is defined as “crystalline resin”, and other resins, specifically, half A resin having a value range exceeding 6 ° C. or a resin having no clear endothermic peak is defined as an amorphous resin (amorphous polymer). In addition, even if it does not have a clear endothermic peak in the second temperature raising step, it is “crystalline resin” if it has a clear endothermic peak in the first temperature raising step. The amorphous resin used in the present invention is preferably a resin that does not have a clear endothermic peak.

As an index indicating the degree of compatibilization between the crystalline polyester resin A and the amorphous resin B, it has been found that it is most effective to express the change in the endothermic peak temperature derived from the crystalline resin A in differential scanning calorimetry (DSC). did.
This indicates that when the crystalline polyester resin A and the amorphous resin B are compatibilized, the crystallinity of the crystalline polyester resin A partially collapses and a melting point drop of the crystalline resin occurs. When the solubilization is remarkable, the endothermic peak temperature derived from the crystalline resin A is also significantly lowered.
In this embodiment, the endothermic peak temperature of the crystalline polyester resin A is TmA [° C.], and the endothermic peak temperature of the crystalline polyester resin A in the mixture of the crystalline polyester resin A and the amorphous resin B is TmAB [° C.]. The difference obtained by subtracting TmAB [° C.] from TmA [° C.] is preferably 5 ° C. or higher and 20 ° C. or lower, and more preferably 8 ° C. or higher and 15 ° C. or lower.
When the difference obtained by subtracting TmAB [° C.] from TmA [° C.] is 5 ° C. or higher and 20 ° C. or lower, it indicates that the crystalline polyester resin and the amorphous resin B have an appropriate compatibility. When the difference obtained by subtracting TmA [° C.] from TmA [° C.] is 5 ° C. or less, the compatibility between the crystalline polyester resin and the amorphous resin B is low, and the crystalline polyester resin and the amorphous resin B A phase-separated sea-island structure tends to decrease the strength of the carrier-coated resin layer due to the physical properties inherently possessed by the crystalline polyester resin A. On the other hand, the difference obtained by subtracting TmAB [° C] from the TmA [° C]. Is 20 ° C. or higher, the compatibility increases, and it becomes difficult to express the advantages inherent in the crystalline polyester resin A, and there is a concern that the coating resin layer itself may be plasticized. There exists a tendency for blocking property to fall.

Here, the endothermic peak temperature, TmA [° C.] and TmAB [° C.] are measured by the heat of a differential scanning calorimeter (manufactured by Max Science Co., Ltd .: DSC3110, thermal analysis system 001, hereinafter sometimes referred to as “DSC”). Measurement was performed using an analyzer. In the first temperature raising step, the temperature is raised from 25 ° C. to 150 ° C. at a rate of 10 ° C. per minute, held at 150 ° C. for 5 minutes, and then liquefied nitrogen is used to reach 0 ° C. at a rate of 10 ° C. per minute. After the temperature was held at 0 ° C. for 5 minutes, the temperature was raised again from 0 ° C. to 150 ° C. at a rate of 10 ° C. as the second temperature raising step, and the obtained differential scanning calorimetry curve was analyzed according to JISK-7121. An endothermic peak was obtained.
The TmAB [° C.] is prepared by mixing the crystalline polyester resin A and the amorphous resin B with a powder at a mixing ratio used in the coating layer of the carrier, and then placing the sample on an aluminum dish. The sample was measured by standing at 150 ° C. for 2 hours, gradually cooling at room temperature (25 ° C.), and then pulverizing the molten sample with a mortar.

(Crystalline polyester resin A)
Although there is no restriction | limiting in particular as crystalline polyester resin, It is melt | dissolved in a solvent that the endothermic peak temperature [TmA (degreeC)] derived from crystalline polyester resin A is 50 degreeC or more and 150 degrees C or less. From the viewpoint of coating or heat coating, it is preferably 150 ° C. or lower, and more preferably an endothermic peak temperature of 50 ° C. or higher in order to maintain the fluidity of the carrier in a high temperature environment. An aliphatic crystalline polyester resin having an appropriate melting temperature is more preferable.

The crystalline polyester resin used for carrier formation according to the toner for developing an electrostatic charge image of the present embodiment is synthesized from a polyvalent carboxylic acid component and a polyhydric alcohol component.
In this embodiment, a commercially available product may be used as the polyester resin, or a synthesized product may be used.

Examples of the polyvalent carboxylic acid component include oxalic acid, succinic acid, glutaric acid, adipic acid, peric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12 -Aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid; phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, mesaconic acid Aromatic dicarboxylic acids such as dibasic acids such as, and the like, and anhydrides and lower alkyl esters thereof are also included, but not limited thereto.
Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and the like, and anhydrides thereof. And lower alkyl esters. These may be used individually by 1 type and may use 2 or more types together.

  As the polyhydric alcohol component, an aliphatic diol is preferable, and a linear aliphatic diol having a main chain portion having 7 to 20 carbon atoms is more preferable. If the aliphatic diol is branched, the crystallinity of the polyester resin is lowered and the melting temperature is lowered, which is not preferable. When the number of carbon atoms is less than 7, when the polycondensation with an aromatic dicarboxylic acid is performed, the melting temperature becomes high and fixing at low temperature may be difficult. On the other hand, when it exceeds 20, it is difficult to obtain a practical material. It is easy to become. The carbon number is more preferably 14 or less.

  Specific examples of the aliphatic diol suitably used for the synthesis of the crystalline polyester used in the present embodiment include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecane Examples include, but are not limited to, diol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,14-eicosandecanediol, and the like. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable in view of availability.

  Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like. These may be used individually by 1 type and may use 2 or more types together.

  Among the polyhydric alcohol components, the content of the aliphatic diol component is preferably 80 mol% or more, and more preferably 90 mol% or more. When the content of the aliphatic diol component is less than 80 mol%, the crystallinity of the polyester resin is lowered and the melting temperature is lowered, so that the toner blocking resistance, the image storage stability, and the low-temperature fixability are deteriorated. There is.

  If necessary, monovalent acids such as acetic acid and benzoic acid and monovalent alcohols such as cyclohexanol benzyl alcohol are used for the purpose of adjusting the acid value and the hydroxyl value.

  The method for producing the crystalline polyester resin is not particularly limited, and can be produced by a general polyester polymerization method in which an acid component and an alcohol component are reacted. Examples thereof include direct polycondensation and transesterification. They are manufactured using different types of monomers.

  The production of the crystalline polyester resin can be carried out at a polymerization temperature of 180 ° C. or higher and 230 ° C. or lower, and the reaction system is depressurized as necessary to carry out the reaction while removing water and alcohol generated during condensation. When the monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a solubilizer and dissolved. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. In the case where a monomer having poor compatibility exists in the copolymerization reaction, it is preferable that the monomer having poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance and then polycondensed together with the main component.

Catalysts used in the production of the crystalline polyester resin include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metals such as zinc, manganese, antimony, titanium, tin, zirconium and germanium Compound: Phosphorous acid compound, phosphoric acid compound, amine compound and the like.

  The weight average molecular weight (Mw) of the purified crystalline polyester resin A is preferably in the range of 3,000 to 35,000, and more preferably in the range of 15,000 to 25,000.

  The weight average molecular weight is measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC was performed with a THF solvent using a Tosoh column / TSKgel Super HM-M (15 cm) using a Tosoh GPC / HLC-8120 as a measuring device. The weight average molecular weight is calculated from the measurement result using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample.

  The content of the crystalline polyester resin in the coating resin layer is preferably in the range of 1% by mass to 40% by mass as described above, but the content of the crystalline polyester resin in the coating resin layer will be described later. It is determined by separating a crystalline polyester resin and an amorphous polyester resin using a specific solvent.

(Amorphous resin B)
In the present embodiment, the amorphous resin B used for the carrier coating layer can be used without particular limitation as long as it has compatibility with the crystalline polyester resin A defined by the endothermic peak temperature.
As the amorphous resin B that can be used in the present embodiment, for example, a styrene acrylic resin can also be used. Examples of monomers that can be used in this case include styrenes such as styrene, parachlorostyrene, and α-methylstyrene: methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, and lauryl acrylate. And esters having vinyl groups such as 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, and the like: Vinyl nitriles such as acrylonitrile and methacrylonitrile: Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether: Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone: Polyolefins such as ethylene, propylene and butadiene: Single amount And a copolymer obtained by combining two or more of these, or a mixture thereof. Furthermore, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, etc., non-vinyl It is also possible to use a condensation resin, a mixture of these with the vinyl resin, or a graft polymer obtained when a vinyl monomer is polymerized in the presence of these resins.
From the viewpoint of easy compatibility control with the crystalline polyester resin, it is preferable to use an amorphous polyester resin having a main skeleton structure similar to the crystalline polyester resin A.
The amorphous polyester resin described in detail below is preferable from the viewpoint of availability because it conforms to the TmA-TmAB conditions defined by the formula (1).

(Amorphous polyester resin)
The “amorphous polyester resin” used in the present embodiment is a resin in which a stepwise endothermic change is observed instead of a clear endothermic peak in differential scanning calorimetry (DSC). When using an amorphous polyester resin, it is possible to easily prepare a crosslinked resin particle dispersion described later by adjusting the acid value of the resin or emulsifying and dispersing it using an ionic surfactant. It is advantageous.

The amorphous polyester resin used in the present embodiment is obtained mainly by condensation polymerization of polyvalent carboxylic acids and polyhydric alcohols.
Examples of the polyvalent carboxylic acid include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, and naphthalenedicarboxylic acid; maleic anhydride, fumaric acid, succinic acid, alkenyl anhydride Aliphatic carboxylic acids such as succinic acid and adipic acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid; and the like, and one or more of these polyvalent carboxylic acids are used.
Among these polyvalent carboxylic acids, it is preferable to use aromatic carboxylic acids, and for the purpose of ensuring good fixability, trivalent or higher carboxylic acids (trivalent or higher carboxylic acids) are introduced together with dicarboxylic acids in order to introduce a crosslinked structure or branched structure. It is preferable to use trimellitic acid or its acid anhydride in combination.

Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, and glycerin; cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and the like. Alicyclic diols; aromatic diols such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A; and the like, and one or more of these polyhydric alcohols are used.
Among these polyhydric alcohols, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable. For the purpose of ensuring good fixability, a trihydric or higher polyhydric alcohol (glycerin, trimethylolpropane, pentaerythritol) may be used in combination with the diol in order to introduce a crosslinked structure or a branched structure.

A polyester resin obtained by polycondensation of a polyvalent carboxylic acid and a polyhydric alcohol is further added with a monocarboxylic acid and / or monoalcohol to esterify the hydroxyl group and / or carboxyl group at the polymerization terminal, thereby producing a polyester. The acid value of the resin may be adjusted.
Examples of the monocarboxylic acid include acetic acid, acetic anhydride, benzoic acid, trichloroacetic acid, trifluoroacetic acid, and propionic anhydride. Examples of the monoalcohol include methanol, ethanol, propanol, octanol, 2-ethylhexanol, trifluoroethanol, trichloroethanol, hexafluoroisopropanol, and phenol.

  The amorphous polyester resin is produced by subjecting the polyhydric alcohol and the polyvalent carboxylic acid to a condensation reaction according to a conventional method. For example, the polyhydric alcohol and polyhydric carboxylic acid, if necessary, a catalyst is added and blended in a reaction vessel equipped with a thermometer, a stirrer, a flow-down condenser, Heating at 150 ° C. or more and 250 ° C. or less to continuously remove by-product low-molecular compounds out of the reaction system, stop the reaction when a predetermined acid value is reached, cool the target reactant Manufactured by acquiring.

  As the catalyst used for the synthesis of the amorphous polyester resin, antimony, tin, titanium, and aluminum catalysts are used. Examples thereof include esterification catalysts such as organic metals such as dibutyltin dilaurate and dibutyltin oxide and metal alkoxides such as tetrabutyl titanate. From the viewpoint of environmental impact and safety, titanium is more desirable. The addition amount of the catalyst is preferably in the range of 0.01% by mass to 1.00% by mass with respect to the total amount of raw materials.

The amorphous polyester resin used in the present embodiment preferably has a weight average molecular weight (Mw) in the range of from 5,000 to 100,000, more preferably 10,000, as determined by molecular weight measurement by the GPC method of the THF-soluble matter. It is preferable that it is the range of 60000 or less.
When the weight average molecular weight is in the above range, suitable compatibility with the crystalline polyester resin A can be easily obtained, and a high-quality image can be formed.

  It is desirable that the DSC onset glass transition temperature (Tg) of the amorphous polyester resin is in the range of 45 ° C. or higher and 70 ° C. or lower and the residual monomer amount is 1000 ppm or lower.

  In the coating resin layer in the present embodiment, the mixing ratio of the crystalline polyester resin A and the amorphous resin B is preferably 1/99 to 40/60 in terms of mass. More preferably, it is 10/90 to 30/70. When the content of the crystalline polyester resin A is in the range of 1% by mass or more and 40% by mass, a practically sufficient strength of the coating resin layer can be obtained, and the abrasion resistance of the carrier resin layer, the toner component such as the toner external additive, etc. Reducing the electrification due to contamination of the carrier coating resin layer is suppressed, and the resistance of the carrier coating resin layer by adding the crystalline polyester resin A layer is controlled to an appropriate value, thereby reproducing the solid due to the occurrence of the edge effect in the solid image portion. Even if the subject has a halftone like a photograph, the reproducibility is excellent, and defects at the edge of the colored image area and gloss unevenness at the boundary with the transparent image area occur. It is suppressed.

The amorphous polyester resin and the crystalline polyester resin are taken out from the coating resin layer of the carrier and the amount of dissolved component, molecular weight, endothermic peak temperature of the crystalline polyester resin A, etc. are obtained by the following method. .
First, the carrier is immersed in methyl ethyl ketone (MEK), and the coating resin layer is dissolved at room temperature (20 ° C. to 25 ° C.). This is because when the carrier resin layer contains a crystalline resin and an amorphous resin, almost only the amorphous resin is dissolved in MEK at room temperature. Accordingly, since the amorphous polyester resin is contained in the MEK-soluble component, the amorphous polyester resin can be obtained from the supernatant liquid separated by centrifugation after the dissolution. On the other hand, the solid content after centrifugation is heated and dissolved in THF, and this is heated and filtered with a glass filter to obtain a crystalline polyester resin. With respect to both resins thus obtained, the amount of dissolved components, molecular weight and the like are measured by the above method. Moreover, about crystalline polyester resin, an endothermic peak temperature is measured by the said method.

(Crosslinked resin particles)
The coating layer in this embodiment preferably further contains crosslinked resin particles that impart a negative chargeability to the transparent toner.
Examples of the resin particles include thermoplastic resin particles and thermosetting resin particles. Among these, a thermosetting resin is preferable from the viewpoint of being hardly soluble in a solvent and relatively easy to increase the hardness, and from the viewpoint of imparting negative chargeability to the toner, resin particles made of a nitrogen-containing resin containing N atoms are used. preferable.
Specific examples of the crosslinked resin particles preferably used in the present embodiment include, for example, phenol resin, amino resin, urea-formaldehyde resin, methyl methacrylate resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, epoxy resin and the like. It is done. From the viewpoint of the effect, it is preferable to select particles insoluble in the solvent used when forming the coating layer.
In addition, these resin particles may be used individually by 1 type, and may use 2 or more types together.

The volume average particle diameter of the crosslinked resin particles is, for example, preferably from 0.1 μm to 2.0 μm, and more preferably from 0.2 μm to 1.0 μm. If the average particle size of the resin particles is less than 0.1 μm, the dispersibility of the crosslinked resin particles in the coating resin layer may be extremely deteriorated. Particles are likely to fall off, and the original effect may not be exhibited.
The volume average particle diameter of the crosslinked resin particles is determined by performing the same measurement as the volume average particle diameter of the core material described later.

  The content of the crosslinked resin particles is preferably 5% by volume to 50% by volume, more preferably 5% by volume to 30% by volume, and more preferably 5% by volume to 20% by volume with respect to the entire coating resin layer. Further preferred. When the content of the resin particles is less than 1% by volume, the effect of the resin particles may not be exhibited. When the content exceeds 50% by volume, the resin particles easily fall off, and stable chargeability cannot be obtained. There is a case.

The method for forming the coating layer on the surface of the core is not particularly limited. For example, for forming a coating resin layer containing a resin for forming the coating resin layer and optionally added crosslinked resin particles in a solvent. Examples thereof include a method using a composition.
For example, a dipping method in which the core material is immersed in the coating resin layer forming composition, a spray method in which the coating resin layer forming composition is sprayed on the surface of the core material, and the coating resin layer in a state where the core material is suspended by flowing air Examples thereof include a kneader coater method in which a solvent is removed by mixing with a forming composition. Among these, the kneader coater method is preferable.

The solvent used in the composition for forming the coating resin layer is not particularly limited as long as it can dissolve the crystalline polyester resin A and the amorphous resin B because it does not remain in the layer after the coating resin layer is formed. Rather, it is selected from solvents known per se.
Specific examples include aromatic hydrocarbons such as ethyl acetate, toluene and xylene; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane and the like, which are selected according to the resin constituting the coating layer. Is done.

In the coating resin layer, the resin particles are preferably dispersed and contained. However, since the resin particles are uniformly dispersed in the thickness direction of the coating resin layer and the tangential direction of the carrier surface, the carrier characteristics are stable. To do. Unlike metal oxide particles or carbon black particles, which are usually used for the preparation of chargeability, the resin particles are stably fixed to the coating resin layer, and carrier deterioration is prevented for a long time. Therefore, even when applied to the transparent toner as in the present embodiment, the occurrence of color unevenness and gloss unevenness in the formed image is suppressed.
Further, the coating resin layer is not limited to a single layer, and may be composed of two or more layers.

The mass ratio of the core material to the resin coating layer is 100: 0.5 to 100: 4.0. The reason for this range is that even if the resin coating layer is worn due to stress or the like in the developing machine, it is possible to suppress an extreme decrease in carrier resistance. When the resin coating ratio with respect to the core material 100 is 0.5 or more, it is preferable that the surface exposure of the core material particles is appropriately maintained and the development electric field is difficult to be injected. If it exceeds 4.0, carrier manufacturability is difficult and the fluidity of the developer in the developing machine may deteriorate.

  The coverage of the core material surface by the coating resin layer is preferably 95% or more, more preferably 98% or more, and the closer to 100%, the more preferable. When the coverage is less than 95%, charge injection into the carrier occurs when used for a long period of time, and the carrier that has undergone charge injection moves onto the photoconductor, resulting in white spots on the image. May end up.

  In addition, the coverage of a coating resin layer is calculated | required by XPS measurement (X-ray photoelectron spectroscopy measurement). JPS 80 manufactured by JEOL Ltd. is used as the XPS measuring apparatus, and the measurement is performed by using MgKα ray as the X-ray source, setting the acceleration voltage to 10 kV and the emission current to 20 mV, and constituting the coating resin layer. Element (usually carbon) and main elements constituting the core material (for example, iron and oxygen when the core material is an iron oxide-based material such as magnetite) are measured (hereinafter, the core material is an iron oxide-based material) It will be explained assuming the case). Here, the C1s spectrum is measured for carbon, the Fe2p3 / 2 spectrum is measured for iron, and the O1s spectrum is measured for oxygen.

Based on the spectrum of each of these elements, the number of carbon, oxygen, and iron elements (A _C + A _O + A _Fe ) is obtained, and the obtained carbon, oxygen, and iron element number ratio is expressed by the following formula (2). Based on this, the iron content rate of the core material alone and after the core material was coated with the coating resin layer (carrier) was determined, and then the coverage rate was determined by the following formula (3).
・ Formula (2)
Iron content rate (atomic%) = A _Fe / (A _C + A _O + A _Fe ) × 100
・ Formula (3)
Coverage (%) = {1- (iron content of carrier) / (iron content of core material)} × 100

  In addition, when using materials other than iron oxide as a core material, the spectrum of the metal element which comprises a core material besides oxygen is measured, and it is the same according to above-mentioned Formula (2) and Formula (3) If coverage is calculated, the coverage can be obtained.

  The average film thickness of each coating resin layer is preferably from 0.1 μm to 10 μm, more preferably from 0.1 μm to 3.0 μm, and still more preferably from 0.1 μm to 1.0 μm. When the average thickness of the coating resin layer is less than 0.1 μm, there may be a decrease in resistance due to peeling of the coating resin layer when used for a long time or it may be difficult to sufficiently control the pulverization of the carrier. On the other hand, when the average film thickness of the coating resin layer exceeds 10 μm, it may take time to reach the saturation charge amount.

The average thickness (μm) of the coating resin layer is such that the true specific gravity of the core material is ρ (dimensionless), the volume average particle diameter of the core material is d (μm), the average specific gravity of the coating resin layer is ρ _C , and the core material 100 When the total content of the coating resin layer with respect to parts by weight is W _C (parts by weight), it is obtained as in the following formula (4).
・ Formula (4)
Average film thickness (μm) = [amount of coating resin per carrier (including all additives such as conductive powder) / surface area per carrier] ÷ average specific gravity of coating resin layer
= [4 / 3π · (d / 2) ³ · ρ · W _C ] / [4π · (d / 2) ² ] ÷ ρ _C
= (1/6) · (d · ρ · W _C / ρ _C )

−Core material−
Next, the core material used for the carrier of this embodiment will be described.
The core material used for the carrier of the present embodiment is not particularly limited, and a known core material for carriers is used. Examples include magnetic metals such as iron, steel, nickel, cobalt, alloys of these with manganese, chromium, rare earths, and magnetic oxides such as ferrite and magnetite. It is desirable to be a carrier. As a core material suitably used in the present embodiment, ferrite particles are preferable because it is easy to eliminate surface variations and the charging property is stable.

  The core material is formed by granulation and sintering, but is preferably finely pulverized as a pretreatment. The pulverization method is not particularly limited, and pulverization can be performed according to a known pulverization method. Specific examples include a mortar, a ball mill, and a jet mill. Although the final pulverized state in the pretreatment varies depending on the material and the like, the volume average particle size is preferably 2 μm or more and 10 μm or less. If it is less than 2 μm, the desired particle size may not be obtained. If it exceeds 10 μm, the particle size may become too large, or the circularity may become small.

  In addition, the sintering temperature is preferably kept lower than in the conventional case. Specifically, although it varies depending on the material used, 500 ° C. or more and 1200 ° C. or less is preferable, and 600 ° C. or more and 1000 ° C. or less is more preferable. . If the sintering temperature is less than 500 ° C., the magnetic force required for the carrier may not be obtained. If the sintering temperature exceeds 1200 ° C., the crystal growth is fast, the internal structure tends to be nonuniform, and cracks and cracks occur. Easy to enter.

  In order to keep the sintering temperature low, in the sintering process, it is preferable to perform preliminary sintering stepwise. Therefore, it is preferable to increase the time required for the entire sintering.

  The volume average particle diameter of the core material is preferably 10 μm to 500 μm, more preferably 30 μm to 150 μm, and still more preferably 30 μm to 100 μm. When the volume average particle diameter of the core material is less than 10 μm, when used as a developer for developing an electrostatic image, the adhesion force between the toner and the carrier is increased, and the development amount of the toner may be reduced. On the other hand, if it exceeds 500 μm, the magnetic brush becomes rough, and it may be difficult to form a fine image.

  As for the magnetic force of the core material, the saturation magnetization at 3000 oersted is preferably 50 emu / g or more, and more preferably 60 emu / g or more. If the saturation magnetization is weaker than 50 emu / g, the carrier may be developed on the photoreceptor together with the toner.

  As a device for measuring magnetic properties, a vibrating sample type magnetic measuring device VSMP10-15 (manufactured by Toei Kogyo Co., Ltd.) is used. The measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement applies an applied magnetic field and sweeps up to 3000 oersted. Next, the applied magnetic field is decreased to create a hysteresis curve on the recording paper. Saturation magnetization, residual magnetization, and coercive force are obtained from the curve data. In this embodiment, the saturation magnetization indicates the magnetization measured in a 3000 oersted magnetic field.

The volume electric resistance (volume resistivity) of the core material is preferably in the range of 10 ⁵ Ω · cm to 10 ^9.5 Ω · cm, and in the range of 10 ⁷ Ω · cm to 10 ⁹ Ω · cm. More preferably. If the volume electric resistance is less than 10 ⁵ Ω · cm, when the toner concentration in the developer decreases due to repeated copying, charges may be injected into the carrier and the carrier itself may be developed. On the other hand, if the volume electric resistance is larger than 10 ^9.5 Ω · cm, the image quality may be adversely affected, such as a prominent edge effect or pseudo contour.
The volume electric resistance (Ω · cm) of the core material is measured by the same method as described above.

<Characteristics of carrier>
The weight average particle diameter of the carrier is preferably 15 μm or more and 50 μm or less, and more preferably 25 μm or more and 40 μm or less. When the weight average particle diameter of the carrier is smaller than 15 μm, the carrier contamination may be deteriorated. On the other hand, if the weight average particle diameter of the carrier is larger than 50 μm, toner deterioration due to stirring may become remarkable.

  The weight average particle diameter of the carrier is measured using Coulter Multisizer II (manufactured by Beckman-Coulter). As the electrolytic solution, ISOTON-II (manufactured by Beckman Coulter, Inc.) is used.

  As a specific measurement method, a measurement sample is added in a range of 0.5 mg to 50 mg in 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant, and this is added from 100 ml of the electrolyte solution. Add into 150 ml. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute, and the particle size is 2.0 μm or more and 60 μm or less using the Coulter Multisizer II type aperture having an aperture diameter of 100 μm. The particle size distribution of the particles in the range is measured. The number of particles to be measured is 50,000.

  In the measured particle size distribution, a cumulative distribution is drawn from the smaller diameter side with respect to the divided particle size range (channel), and the particle size at which 50% is accumulated is defined as the weight average particle size.

  Further, the shape factor SF1 of the carrier is preferably 120 or more and 145 or less. This is to achieve both high image quality and cleanability.

The carrier shape factor SF1 means a value obtained by the following equation (5).
Formula (5) SF1 = 100π × (ML) ² / (4 × A)
Here, ML is the maximum length of the carrier particles, and A is the projected area of the carrier particles. The maximum length and projected area of the carrier particles are determined by observing the carrier particles sampled on the slide glass with an optical microscope and importing them into an image analyzer (LUZEX III, manufactured by NIRECO) through a video camera for image analysis. Is obtained by The number of samplings at this time is 100 or more, and the shape factor shown in Expression (5) is obtained using the average value.

The saturation magnetization of the carrier is preferably 40 emu / g or more, and more preferably 50 emu / g or more.
As a device for measuring magnetic properties, a vibrating sample type magnetic measuring device VSMP10-15 (manufactured by Toei Kogyo Co., Ltd.) is used. The measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement applies an applied magnetic field and sweeps up to 1000 oersted. Next, the applied magnetic field is decreased to create a hysteresis curve on the recording paper. Saturation magnetization, residual magnetization, and coercive force are obtained from the curve data. In the present embodiment, the saturation magnetization indicates the magnetization measured in a 1000 Oersted magnetic field.

The volume electric resistance of the carrier is preferably controlled in the range of 1 × 10 ⁹ Ω · cm to 1 × 10 ¹⁴ Ω · cm, preferably 1 × 10 ¹⁰ Ω · cm to 1 × 10 ¹⁴ Ω · cm. The range is more preferable, and the range of 1 × 10 ¹¹ Ω · cm to 1 × 10 ¹³ Ω · cm is more preferable.
When the volume electrical resistance of the carrier exceeds 1 × 10 ¹⁴ Ω · cm, the resistance becomes high and it becomes difficult to work as a developing electrode at the time of development. There is. On the other hand, if it is less than 1 × 10 ⁹ Ω · cm, the resistance becomes low, so that when the toner concentration in the developer is lowered, charge is injected from the developing roll into the carrier, and the carrier itself is developed. It may be easier.

<Transparent toner for electrostatic latent image development>
The developer for developing an electrostatic image according to this embodiment includes at least the transparent toner according to this embodiment.
The transparent toner used in this embodiment will be described. The transparent toner according to the present embodiment is usually applied to a non-formation region of an image or further to the surface of the color toner image after forming the color toner image, and gives gloss to the formed image. A high-quality image is formed by eliminating the difference in gloss between the image and the recording medium. The transparent toner is a toner used for a transparent toner image, and specifically refers to a substantially colorless toner in which the content of a colorant such as a dye or pigment is 0.01% by mass or less.

  The transparent toner used in the exemplary embodiment is not particularly limited by the manufacturing method as long as the shape index and the particle diameter are in the ranges described below. For example, the binder resin and the release agent, and charged as necessary. Kneading and pulverizing method for kneading, pulverizing and classifying control agents, etc., a method for changing the shape of particles obtained by kneading and pulverizing method with mechanical impact force or thermal energy, emulsifying the polymerizable monomer of binder resin An emulsion polymerization agglomeration method and a binder resin are obtained by mixing a dispersion formed by polymerization and a dispersion of a release agent and, if necessary, a dispersion of a charge control agent, and aggregating and heat-fusing to obtain toner particles. Suspension polymerization method in which a polymerizable monomer, a colorant, a release agent, and a charge control agent, if necessary, are suspended in an aqueous solvent for polymerization, a binder resin and a release agent, necessary Depending on the solution, a solution such as a charge control agent may be suspended in an aqueous solvent and granulated. You can use. In addition, a known method such as a production method in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to give a core-shell structure can be used, but from the viewpoint of shape control and particle size distribution control Suspension polymerization method, emulsion polymerization aggregation method, and dissolution suspension method, which are produced from an aqueous solvent, are preferred, and emulsion polymerization aggregation method is particularly preferred.

  The transparent toner particles include a binder resin and a release agent, and silica or a charge control agent may be used if necessary. The toner particles preferably have an average particle size of 2 μm or more and 12 μm or less, more preferably 3 μm or more and 9 μm or less. By using toner having an average shape index (ML2 / A) of 115 or more and 140 or less, high development and transfer properties can be obtained, and high gloss can be imparted to the image.

  Binder resins used for forming transparent toner particles include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate. Α-methylene such as methyl esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers such as aliphatic monocarboxylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone; Examples of the binder resin include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer. Styrene-maleic anhydride copolymer, polyethylene, polypropylene and the like, and polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  Typical examples of the release agent used for the transparent toner particles include low molecular weight polyethylene, low molecular weight polypropylene, Fischer tropical wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  In addition, a charge control agent may be added to the transparent toner as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The transparent toner in this embodiment may be either a magnetic toner containing a magnetic material or a non-magnetic toner not containing a magnetic material.

  Fine particles may be externally added to the transparent toner particles for various purposes. In order to reduce adhesion and control charging, it is preferable to add a large-diameter inorganic oxide having a volume average particle size of 20 nm to 300 nm. These fine inorganic oxide particles include silica, titanium oxide, metatitanic acid, aluminum oxide, magnesium oxide, alumina, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, Fine particles such as antimony oxide, magnesium oxide, and zirconium oxide can be used. Among these, it is desirable to use one selected from silica, titanium oxide, and metatitanic acid from the viewpoint of precise charge control of the toner added with lubricant particles and cerium oxide.

In particular, in an image that requires high transfer efficiency, the silica is preferably monodispersed spherical silica having a true specific gravity of 1.3 to 1.9 and a volume average particle size of 80 nm to 300 nm. . By controlling the true specific gravity to 1.9 or less, peeling from the toner particles can be suppressed. Further, by controlling the true specific gravity to 1.3 or more, aggregation and dispersion can be suppressed. The true specific gravity of the monodispersed spherical silica is more preferably in the range of 1.4 to 1.8.
When the average particle diameter of the monodispersed spherical silica is less than 80 nm, it tends to not work effectively for reducing the non-electrostatic adhesion between the toner and the photoreceptor. In particular, monodispersed spherical silica is easily embedded in toner particles due to stress in the developing device, and the effect of improving developability and transferability is likely to be significantly reduced. On the other hand, if it exceeds 300 nm, it will be easy to detach from the toner base particles, and it will not work effectively to reduce the non-electrostatic adhesion force, and at the same time it will easily move to the contact member, secondary obstructions such as charging inhibition and image quality defects. It is easy to cause. The average particle size of the monodispersed spherical silica is more preferably 100 nm or more and 200 nm or less from the viewpoint of effects.

  In order to clean a transparent toner close to a spherical shape, it is preferable to add lubricant particles to the toner particles because reducing the frictional force between the toner and the photosensitive member at the blade nip is the key. Lubricant particles include solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids, aliphatic higher alcohols, and fatty acid metal salts; low molecular weight polyolefins such as polypropylene, polyethylene, and polybutene; silicones having a softening point upon heating; Aliphatic amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide; plant waxes such as carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil, etc .; like beeswax Mineral waxes; mineral waxes such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc .; and their modified products can be used alone or are they No It may be used in combination.

  Among these, fatty acid metal salts and aliphatic alcohols are particularly preferable. As the fatty acid metal salts, metal salts of fatty acids having 10 to 50 carbon atoms with zinc, aluminum, magnesium, calcium and the like are preferably used. As the aliphatic alcohol, a higher aliphatic alcohol having 16 to 150 carbon atoms is preferably used.

  The volume average particle size of the lubricant particles is preferably in the range of 0.1 μm or more and 10 μm or less, and the particles having the chemical structure may be pulverized to make the particle sizes uniform. The amount added to the toner base particles is preferably in the range of 0.05 parts by weight to 2.0 parts by weight, and 0.1 parts by weight to 1.5 parts by weight with respect to 100 parts by weight of the toner base particles. The following range is more preferable.

  In addition, for the purpose of removing adhered matter and deteriorated matter on the surface of the photoreceptor, inorganic fine particles, organic fine particles, composite fine particles obtained by attaching inorganic fine particles to the organic fine particles, and the like can be added.

  The transparent toner used in the exemplary embodiment can be produced by mixing the toner particles and the external additive with a Henschel mixer or a V blender. In addition, when the toner particles are produced by a wet method, external addition can be performed by a wet method.

<Characteristics of transparent toner>
The volume average particle diameter of the transparent toner particles according to this embodiment is preferably in the range of 4 μm to 9 μm, more preferably in the range of 4.5 μm to 8.5 μm, and even more preferably in the range of 5 μm to 8 μm. It is a range. When the volume average particle diameter is less than 4 μm, the toner fluidity is lowered, and the chargeability of each particle tends to be lowered. Further, since the charge distribution is widened, fogging on the background, toner spillage from the developing device, and the like are likely to occur. On the other hand, if it is smaller than 4 μm, the cleaning property may be extremely difficult. When the volume average particle diameter is larger than 9 μm, the resolution is lowered, so that it is difficult to obtain gloss with no variation, and it may be difficult to satisfy the recent demand for high image quality.

  The volume average particle size may be measured using a Coulter Multisizer II (manufactured by Coulter, Inc.) with an aperture diameter of 50 μm. At this time, the measurement was performed after the toner was dispersed in an electrolyte aqueous solution (Isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.

  Further, as described above, the transparent toner particles according to the present embodiment are preferably spherical with a shape factor SF1 in the range of 110 to 140. When the shape is spherical in this range, transfer efficiency and image density are improved, and high-quality gloss is imparted to the image.

  The transparent toner according to the present embodiment may constitute a toner set together with at least one color toner selected from the group consisting of cyan toner, magenta toner, yellow toner, and black toner, which will be described later.

<Production method of full color toner>
The production method of the full color toner used together with the transparent toner in the gloss imparting device of the present embodiment is not particularly limited, and is a known dry method such as a kneading / pulverizing method, or a wet method such as an emulsion aggregation method or a suspension polymerization method. Etc. are produced. Among these methods, an emulsification aggregation method that makes it easy to produce a toner having a low release agent exposure rate on the toner surface by using a core-shell structure is preferable. Hereinafter, the manufacturing method of the color toner according to the exemplary embodiment by the emulsion aggregation method will be described in detail.

  The full color toner used in the present embodiment is not particularly limited by the production method as long as it satisfies the above shape index and particle size. For example, the binder resin and the colorant, the release agent, and the like are necessary. Kneading and pulverizing methods for kneading, pulverizing, and classifying the charge control agent, etc., a method for changing the shape of the particles obtained by the kneading and pulverizing method by mechanical impact force or thermal energy, Emulsion polymerization of the polymer, and the resulting dispersion is mixed with a dispersion of a colorant, a release agent and, if necessary, a charge control agent, and agglomerated and heat-fused to obtain toner particles. Aggregation method, suspension polymerization method in which a polymerizable monomer and a colorant, a release agent, and a charge control agent, if necessary, are suspended in an aqueous solvent for polymerization to obtain a binder resin. Resin and colorant, mold release agent, if necessary, solution of charge control agent in aqueous solvent Nigosa dissolved suspension method or the like for granulating can be used. In addition, a known method such as a production method in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to give a core-shell structure can be used, but from the viewpoint of shape control and particle size distribution control Suspension polymerization method, emulsion polymerization aggregation method, and dissolution suspension method, which are produced from an aqueous solvent, are preferred, and emulsion polymerization aggregation method is particularly preferred.

  Similar to the toner particles used for the transparent toner, the toner particles in the full-color toner are configured to include a binder resin and a release agent, and include silica and a charge control agent as necessary. The average particle diameter of the toner particles is preferably 2 μm or more and 12 μm or less, and more preferably 3 μm or more and 9 μm or less. By using a full color toner particle having an average shape index (ML2 / A) of 115 or more and 140 or less, a high development, transferability, and high quality image can be obtained.

    Examples of the binder resin used for forming toner particles of the color toner include the same resins as those described above for the transparent toner particles, and typical examples of the binder resin include polystyrene and styrene-acrylic. Examples thereof include acid alkyl copolymers, styrene-alkyl methacrylate copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-maleic anhydride copolymers, polyethylene, and polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  Colorants used in color toners include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green oxa. Rate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 is exemplified as a typical example.

  Typical examples of the release agent used for the color toner particles include low molecular weight polyethylene, low molecular weight polypropylene, Fischer tropical wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  Also, in the color toner, a charge control agent may be added as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner in this embodiment may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  In the color toner particles, fine particles may be externally added for various purposes in the same manner as the transparent toner particles. Examples of transparent toner particles, such as inorganic oxide particles for reducing adhesion and charge control, are also exemplified, and among them, from the viewpoint of performing precise charge control of toner added with lubricant particles and cerium oxide, It is desirable to use one selected from silica, titanium oxide, and metatitanic acid.

Further, as in this embodiment, particularly in an image that requires high transfer efficiency such as a full-color image, the silica has a true specific gravity of 1.3 to 1.9 and a volume average particle size of 80 nm. Monodispersed spherical silica having a particle size of 300 nm or less is preferred. By controlling the true specific gravity to 1.9 or less, peeling from the toner base particles is suppressed. Further, by controlling the true specific gravity to be 1.3 or more, aggregation and dispersion are suppressed. The true specific gravity of the monodispersed spherical silica is more preferably in the range of 1.4 to 1.8.
When the average particle diameter of the monodispersed spherical silica is less than 80 nm, it tends to not work effectively for reducing the non-electrostatic adhesion between the toner and the photoreceptor. In particular, monodispersed spherical silica is easily embedded in toner particles due to stress in the developing device, and the effect of improving developability and transferability is likely to be significantly reduced. On the other hand, if it exceeds 300 nm, it will be easy to detach from the toner particles, and it will not work effectively to reduce the non-electrostatic adhesion force, and at the same time, it will easily move to the contact member, causing secondary obstacles such as charging inhibition and image quality defects. It becomes easy to cause. The average particle size of the monodispersed spherical silica is more preferably 100 nm or more and 200 nm or less from the viewpoint of effects.

  Further, in order to clean the toner close to a spherical shape, it is preferable to add lubricant particles to the full-color toner particles in the same manner as described for the transparent toner particles. Lubricant particles include solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids, aliphatic higher alcohols, and fatty acid metal salts; low molecular weight polyolefins such as polypropylene, polyethylene, and polybutene; silicones having a softening point upon heating; Aliphatic amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide; plant waxes such as carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil, etc .; like beeswax Animal-based waxes; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc .; and their modified products; Le are preferred, the fatty acid metal salt, and 50 or less fatty acid having 10 or more carbon atoms, zinc, aluminum, magnesium, metal salts of calcium, and the like are preferably used. As the aliphatic alcohol, a higher aliphatic alcohol having 16 to 150 carbon atoms is preferably used.

  The volume average particle size of the lubricant particles is preferably in the range of 0.1 μm or more and 10 μm or less, and the particles having the above chemical structure may be pulverized to have the same particle size. The amount added to the toner particles is preferably in the range of 0.05 to 2.0 parts by weight with respect to 100 parts by weight of the toner particles, preferably 0.1 to 1.5 parts by weight. A range is more preferable.

  In addition, for the purpose of removing adhered matter and deteriorated matter on the surface of the photoreceptor, inorganic fine particles, organic fine particles, composite fine particles obtained by attaching inorganic fine particles to the organic fine particles, and the like can be added to the full color toner.

  The full color toner used in the present embodiment can be produced by mixing the toner particles and the external additive with a Henschel mixer or a V blender. In addition, when the toner particles are produced by a wet method, external addition can be performed by a wet method.

<Characteristics of color toner>
The volume average particle diameter of the color toner according to the exemplary embodiment is preferably in the range of 4 μm to 9 μm, more preferably in the range of 4.5 μm to 8.5 μm, and still more preferably in the range of 5 μm to 8 μm. It is. When the volume average particle diameter is less than 4 μm, the toner fluidity is lowered, and the chargeability of each particle tends to be lowered. Further, since the charge distribution is widened, fogging on the background, toner spillage from the developing device, and the like are likely to occur. On the other hand, if it is smaller than 4 μm, the cleaning property may be extremely difficult. If the volume average particle diameter is larger than 9 μm, the resolution decreases, so that sufficient image quality cannot be obtained, and it may be difficult to satisfy recent high image quality requirements.

  The volume average particle size may be measured using a Coulter Multisizer II (manufactured by Coulter, Inc.) with an aperture diameter of 50 μm. At this time, the measurement was performed after the toner was dispersed in an electrolyte aqueous solution (Isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.

  Furthermore, it is preferable that the color toner according to the present exemplary embodiment has a spherical shape with a shape factor SF1 in the range of 110 to 140. When the shape is spherical in this range, transfer efficiency and image density are improved, and a high-quality image is formed.

  In the developer of the present embodiment, the mixing ratio (mass ratio) of the full color toner and the transparent toner and the carrier is desirably in the range of toner: carrier = 6: 100 to 10: 100, and 7: 100 to 9: 100. A range of degree is more desirable.

<Glossing device>
Next, a gloss imparting apparatus according to this embodiment using a transparent developer containing the electrostatic toner for developing an electrostatic charge image according to this embodiment and a carrier having a specific coating resin layer will be described.
The gloss imparting apparatus according to the present embodiment forms a color toner image on the surface of a recording medium by electrophotography using a color toner containing a thermoplastic resin and a colorant, and then implements the present invention around the color toner image. A gloss imparting device that imparts gloss to an image by transferring and fixing the developer according to the embodiment, and a transparent toner image holding body that holds a transparent toner image, and the surface of the transparent toner image holding body. A transparent toner image forming means for forming a transparent toner image made of the developer and a transparent toner image formed on the surface of the transparent toner image holding member, and transferring the surface of the recording medium to the surface on which the color toner image is formed. Heating and pressurizing means for fixing by heating and pressure contact, and after cooling the transparent toner image and color toner image transferred and fixed on the surface of the recording medium, The recording medium on which the toner image is formed, characterized in that it comprises a cooling peeling means for peeling the transparent toner image bearing member.

  First, a color toner image is formed by a general image forming apparatus. According to the image forming apparatus, a latent image holding member, a developing unit that develops an electrostatic latent image formed on the latent image holding member as a toner image with a developer, and a latent image holding member formed on the latent image holding member. A transfer means for transferring the toner image onto the transfer body, a fixing means for fixing the toner image transferred onto the transfer body, and the latent image holder by rubbing with a cleaning member to clean transfer residual components. It is common to have a cleaning means. A gloss imparting device that imparts gloss to a color toner image formed on a recording medium by such an image forming apparatus is disposed adjacent to the image forming apparatus, and continuously performs color toner image formation and gloss imparting. Since this is generally performed, an example in which the gloss providing device is disposed adjacent to the image forming apparatus will be described below as an example.

  In order to carry out the fixing by the cooling and peeling means, the gloss imparting device is at least transparent by heating and pressing a recording medium having a transparent toner image made of transparent toner transferred on at least the surface of the color toner image. A fixing unit including a fixing unit configured to fix the toner image, the fixing unit being arranged in contact with each other so as to form a press-contact portion, and at least one of which is rotatable; At least a member, and the recording medium having a surface onto which the transparent toner image is transferred is in close contact with the surface of the endless belt-like fixing member. The endless belt-like fixing member of the pressed recording medium in a state where the surface on which the transparent toner image is transferred and the surface of the endless belt-like fixing member are in close contact with each other A function of cooling while more transport, the cooled recording medium, it is particularly desirable to include a function of peeled from the endless belt-shaped fixing member surface.

Hereinafter, the gloss imparting apparatus according to the present embodiment will be specifically described together with the configuration of an image forming apparatus provided adjacently.
FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus including the gloss applying apparatus according to the present embodiment. The image forming apparatus shown in FIG. 1 is largely a color toner image forming apparatus (reference numerals 2 to 16) for forming a color toner image, and after forming a transparent toner image, the transparent toner image and the color toner image In order to fix the toner image on the surface of the recording medium, it is divided into a gloss applying device (reference numerals 20 to 33) with an image forming unit for forming a transparent toner image, and both are connected by a conveying device 19.

In the color toner image forming apparatus, first, the original 1 to be read is irradiated with light by the illumination 2, and the reflected light is read by the color scanner 3. The read signal is sent to an image processing device (image signal forming device) 4 where it is separated into each color of yellow Y, magenta M, cyan C and black K, and an image signal for controlling exposure is obtained by the exposure device. It is sent to a certain optical system 6.
In the optical system 6, the laser diode 5 emits light for each color component, and the surface of the organic photoconductor (photoconductor) 8 is irradiated with image-like light X for each color component. On the other hand, while the organic photoreceptor 8 rotates in the direction of arrow A, the surface is first charged by the charger (charging device) 7 and then exposed by the optical system 6 described above, and the developing devices 9 to 12 are exposed. It is used for development.

  For example, taking the yellow Y color as an example, the surface of the organic photoreceptor 8 is irradiated by the optical system 6 with the light color-separated into the yellow Y color component by the image processing device 4. The surface of the organic photoreceptor 8 is charged in advance by the charger 7, and the portion irradiated with the light is charged to the opposite polarity to form a latent image. Then, the latent image on the surface of the organic photoreceptor 8 is developed by the yellow developing device 9 with yellow Y color toner. Further, the organic photoreceptor 8 rotates in the direction of arrow A, and is transferred onto the surface of the intermediate transfer belt (intermediate transfer body) 13 by electrostatic attraction of the transfer corotron 14. After the transfer, the surface of the organic photoreceptor 8 is charged by the charger 7 by further rotation in the direction of the arrow A to prepare for image formation of the next color.

Subsequent to the yellow Y color, the same operation is performed for each color of magenta M, cyan C, and black K, and the latent image is sequentially developed by the magenta developing device 10, the cyan developing device 11, and the black developing device 12, and the intermediate transfer belt. 13 is laminated. The intermediate transfer belt 13 rotates in the direction of arrow B as the organic photoconductor 8 rotates at the time of transferring each color. When the transfer is completed, the intermediate transfer belt 13 rotates in the opposite direction and returns to the original position, and the next color is transferred. When the image is printed, it is laminated on the color toner image transferred before that. When all four colors are stacked, they are rotated in the direction of arrow B as they are and sent to the nip portion sandwiched between transfer rolls (secondary transfer devices) 15 and 16. A sheet 17 that is a recording medium on which an image is to be formed is inserted in the nip portion in the direction of arrow C in a state of being in contact with the intermediate transfer belt 13 on the surface. The laminated color toner images are transferred onto the surface of the paper 17 by the electrostatic action of the transfer rolls 15 and 16.
The sheet 17 on which the color toner image has been transferred is conveyed by a conveying device 19 to a gloss applying device with an image forming unit.

  The gloss applying device includes an endless belt-like transparent toner image holding body 20 that also functions as a fixing member stretched between a plurality of rolls 30, 32, and 33, and a specific transparent toner on the surface of the transparent toner image holding body 20. A transparent toner image forming means 21 for forming an image, a transparent toner image holding body 20 having a transparent toner image formed on the surface thereof, and a recording medium 17 on which a color toner image is formed are sandwiched and overlapped to form a transparent toner image Is transferred to the surface on which the color toner image is formed, and the transfer fixing means 22 for heating and pressing, and the transfer toner fixing means 22 covers the surface of the color toner image or the periphery thereof with the transparent toner image covered therewith. A cooling heat sink (cooling means) 23 that cools the recording medium 17 that has been transferred and fixed.

  As the transparent toner image holding member 20, for example, an image formed of a fixing belt formed in an endless belt shape with a polymer film such as polyimide is used. Further, it is desirable that the resistance value of the transparent toner image carrier 20 is adjusted to a specific value by dispersing conductive additives such as conductive carbon particles and conductive polymer. The shape of the transparent toner image holding member 20 is not limited to an endless shape. For example, the transparent toner image holding member 20 may have various shapes such as a web shape, a web shape, a sheet shape, etc. It is desirable to use a belt.

  The surface of the transparent toner image carrier 20 is preferably coated with a silicone resin and / or a fluorine resin from the viewpoint of releasability. The transparent toner image carrier 20 preferably has a surface glossiness of 60 or more as measured by a 75 ° gloss meter.

  The transparent toner image forming unit 21 forms a transparent toner image made of a transparent developer containing a carrier according to the present embodiment on the surface of the transparent toner image holding member 20. As long as this purpose is satisfied, a developing device known per se is diverted and used. As the transparent toner image forming means 21, for example, a two-component developing device is provided at a position where a counter electrode member such as a roll to which a ground or bias voltage is applied is in contact with the back surface of the transparent toner image holding member 20. May be a device that directly develops the transparent toner image on the surface of the transparent toner image holding member 20 by the two-component developing device. In this case, the temperature of the transparent toner image holding member 20 at the position of the device for directly developing the transparent toner is desirably 60 ° C. or less.

  As shown in FIG. 1, the transparent toner image forming means 21 forms a latent image by exposing a photosensitive drum 24, a charging device 25 for charging the surface of the photosensitive drum 24, and the surface of the photosensitive drum 24. An exposure device 26 composed of a laser optical system, an LED array, and the like; a transparent toner image signal forming device 27 for controlling the area where the transparent toner image is formed on the surface of the recording medium 17 and the amount of the transparent toner image; A transparent toner image developing device 28 for developing a latent image on the surface of the photosensitive drum 24 with a developer layer containing transparent toner to obtain a transparent toner image, and a transparent toner image on the surface of the photosensitive drum 24 And a transfer device 29 for transferring to the surface of the holding body 20.

The photosensitive drum 24 is not particularly limited, and a conventionally known one can be adopted without any problem. The photosensitive drum 24 may be a single layer structure, or may be a multilayer structure and a function separation type. The material of the photoconductor drum 24 may be an inorganic photoconductor such as selenium or amorphous silicon, or an organic photoconductor.
As the charging device 25, for example, a contact charging device using a conductive or semiconductive member (for example, a roller, a brush, a film, or a rubber blade), or non-corrosion charging such as corotron charging or scorotron charging using corona discharge is used. Means known per se, such as a contact-type charging device, are used.

  As the exposure device 26, a known exposure means such as a combination of a semiconductor laser and a scanning device, a laser optical system, an LED head, or a halogen lamp is used. In order to realize a desirable mode in which the exposure image area, that is, the position of the surface of the recording medium on which the transparent toner image is formed is changed as necessary, it is desirable to use a laser optical system or an LED head.

As the transparent toner image signal forming device 27, any conventionally known means is used as long as a signal capable of forming a transparent toner image at a specific position on the surface of the recording medium 17 is formed. The transparent toner image signal forming apparatus 27 may form a transparent toner image formation signal based on the image data output from the image processing apparatus 4 in the color toner image forming apparatus described above. Good.
As the transparent toner image developing device 28, a conventionally known developing device is used as long as it has a function of forming a transparent toner image on the surface of the photosensitive drum 24.

  As the transfer device 29, for example, an electric field is created between the photosensitive drum 24 and the transparent toner image holding member 20 using a conductive or semiconductive member (for example, a roller, a brush, a film, or a rubber blade). , Means for transferring charged transparent toner, or means for transferring the charged transparent toner by corona charging the back surface of the transparent toner image holding body 20 with a corotron charger or a scorotron charger using corona discharge. For example, a conventionally known means is used.

  The area for forming the transparent toner image is, for example, the entire image area covering the entire color toner image on the surface of the recording medium 17. However, the present invention is not limited to this, and may be, for example, the entire surface of the recording medium 17, or may select only a region that exhibits particularly high gloss, such as a photographic image, among color toner images. . In addition, in order to suppress unevenness due to the toner in the color toner image, the toner height of the transparent toner image is changed to equalize the height according to the toner height of the color toner image, or the color toner image is formed. For example, a transparent toner image may be formed only on a region where no color toner is formed, or a transparent toner image may be hardly or not formed on the surface of the color toner image. Furthermore, a mode in which a transparent toner image is formed before forming a color toner image may be used. The expression “the surface of the color image (including the state before fixing (including the color toner image) and / or its surroundings)” includes all these aspects.

  The area for forming the transparent toner image is preferably the entire surface of the recording medium 17 from the viewpoint of obtaining a uniform gloss after fixing. In this case, particularly for the color toner image portion, the area depends on the toner height. Therefore, it is desirable to control the height of the transparent toner image so that the thickness of the entire formed image does not vary.

  Transfer fixing means for transferring the transparent toner image and heating and pressing the transparent toner image holding member 20 on which the transparent toner image is formed and the recording medium 17 on which the color toner image is formed. As 22, a conventionally known one is used. As shown in FIG. 1, the transfer fixing unit 22 forms a transparent toner image between a pair of rolls (a heating roll 30 and a pressure roll 31) driven at a constant speed in the directions of arrows C and C ′. The transparent toner image holding member 20 and the recording medium 17 on which the color image is formed are conveyed while being sandwiched and heated and pressed. Here, one or both of the pair of rolls 30 and 31 has their surfaces heated to a temperature at which the transparent toner melts, for example, by a method including a heat source (not shown) at the center. The rolls 30 and 31 are pressed against each other via the transparent toner image holding member 20. One or both of the pair of rolls 30 and 31 are desirably provided with a silicone rubber or fluororubber layer on the surface thereof, and the length of the nip region to be heated and pressed is in the range of about 1 mm to 8 mm. It is desirable.

As shown in FIG. 1, the endless belt-shaped transparent toner image holding body 20 is rotatably supported by a plurality of rolls 30, 32, and 33 including a heating roll 30, and holds the transparent toner image on the heating roll 30. A pressure roll 31 is in pressure contact with the body 20.
As the heating roll 30 and the pressure roll 31, for example, a surface of a metal core made of aluminum is coated with an elastic body layer (thickness 2 mm) made of silicone rubber and formed to have a specific outer diameter (40 mmφ). Used. Inside the heating roll 30 and the pressure roll 31, for example, a halogen lamp (not shown) of 300 W or more and 350 W or less is disposed as a heating source, and the inside of the heating roll 30 is set to a specific temperature. Is heated from.

  The heating roll 30 and the pressure roll 31 are in pressure contact with each other via the transparent toner image holding body 20, and a specific load is applied by a pressure means (not shown), and the width of the pressure contact portion (nip portion) is 8 mm. It is comprised so that it may become. Further, the transparent toner image holding member 20 is stretched around the heating roll 30, the peeling roll 32, and the driven roll 33, and is moved at a specific moving speed by the heating roll 30 that is driven to rotate in the direction of arrow C by a driving source (not shown). It is rotationally driven in the direction of arrow D at (about 30 mm / sec). As the transparent toner image holding member 20, for example, an endless film made of thermosetting polyimide having a thickness of 80 m is coated with a silicone rubber layer having a thickness of 30 μm.

  Further, on the inner surface side of the transparent toner image holding body 20, between the heating roll 30 and the peeling roll 32, the transparent toner image holding body 20 is forcibly cooled to facilitate subsequent peeling. A cooling heat sink 23 is provided as an apparatus, and the cooling heat sink 23 cools the toner and the recording medium 17. A heat pipe may be used instead of the heat sink. Further, as shown in FIG. 1, a roll having a small curvature is adopted as the roll (peeling roll 32) located at the peeling position, and the roll is peeled off by the waist of the recording medium 17 itself, which is a desirable mode. Note that it is also a desirable aspect to dispose a peeling claw at a site where the transparent toner image carrier 20 and the recording medium 17 are to be peeled off.

Next, a description will be given of a process in which the recording medium 17 on which the color toner image is formed is conveyed by the conveying device 19 and is introduced into the gloss applying device so that the image gloss is applied.
First, as described above, the recording medium 17 on which the color toner image is formed (transferred) is pressed against the heating roll 30 and the pressure roll 31 pressed against the heating roll 30 via the transparent toner image holder 20. The color toner image is introduced into the (nip portion) so as to face the heating roll 30 side.

  FIG. 2 schematically shows a state between the transparent toner image holding member 20 and the recording medium 17 when passing through the press contact portion between the heating roll 30 and the pressure roll 31. In FIG. 2, 34 is a transparent toner image held on the transparent toner image holder 20, 35 is a color toner image formed on the recording medium 17, and a pair of rolls 30 and 31 are omitted. As shown in FIG. 2, the color toner image 35 is heated and melted on the surface of the recording medium 17, and at the same time, the transparent toner image 34 formed on the surface of the transparent toner image holding member 20 is changed to the surface of the color toner image 35. It is transferred to the periphery, heated and melted and fused, and the whole is covered.

  After that, the color toner image 35 and the transparent toner image 34 are heated and melted at a temperature of, for example, about 120 ° C. or more and 130 ° C. or less at the press contact portion between the heating roll 30 and the pressure roll 31 and fixed on the recording medium 17. The recording medium 17 on which the transparent toner image 34 and the color toner image 35 are fixed has the transparent toner image 34 on the surface thereof kept in close contact with the surface of the transparent toner image holder 20. At the same time, it is conveyed in the direction of arrow D. Meanwhile, the transparent toner image holding member 20 is forcibly cooled by the cooling heat sink 23, and after the transparent toner image 34 and the color toner image 35 are cooled and solidified, the release roller 32 supports the waist of the recording medium 17 itself ( Rigidity).

  The surface of the transparent toner image holding member 20 after the peeling process is completed is prepared for the next transfer and fixing process by removing residual toner and the like by a cleaner (not shown) as necessary.

By applying the transparent developer of the present embodiment containing the specific carrier and using the gloss imparting device of the present embodiment, the color toner image is suppressed while suppressing the occurrence of color dullness and image omission in the color toner image. A high-quality image having a high gloss similar to that of a silver salt photograph and having no variation in image thickness is formed.

  Hereinafter, although an Example and a comparative example are given and this embodiment is described in detail more concretely, this embodiment is not limited to these Examples at all.

<Adjustment of resin for coating resin layer of carrier>
(Synthesis Example 1) Preparation of carrier-coated crystalline polyester resin (A) In a heat-dried three-necked flask, 100 mol% sebacic acid dimethyl acid and 100 mol% ethylene glycol, and dibutyltin oxide as a catalyst per 100 parts by mass in total. After adding 0.3 part by mass, the air in the container was brought into an inert atmosphere with nitrogen gas by depressurization, and stirred and refluxed at 180 ° C. for 5 hours with mechanical stirring. Thereafter, the temperature was gradually raised to 230 ° C. under reduced pressure, and the mixture was stirred for 2 hours. When it became viscous, it was air-cooled, the reaction was stopped, and a crystalline polyester resin (A) was synthesized.
The weight average molecular weight (Mw) of the obtained crystalline polyester resin (A) was 15000 by molecular weight measurement (polystyrene conversion) by gel permeation chromatography. Further, when the melting point (Tm) of the crystalline polyester resin (A) was measured by a differential scanning calorimeter (DSC) by the above-described measuring method, it showed a clear endothermic peak, and the endothermic peak temperature was 72.2. ° C.

(Synthesis Example 2) Preparation of crystalline polyester resin (B) for carrier coating In a heat-dried three-necked flask, 100 mol% of dimethyl sebacate and 100 mol% of 1,6-hexanediol, and as a catalyst per 100 parts by mass of these in total After adding 0.3 part by mass of dibutyltin oxide, the air in the container was placed in an inert atmosphere with nitrogen gas by depressurization, and the mixture was stirred and refluxed at 180 ° C. for 5 hours with mechanical stirring. Thereafter, the temperature was gradually raised to 230 ° C. under reduced pressure, and the mixture was stirred for 4 hours. When it became viscous, it was cooled with air, the reaction was stopped, and a crystalline polyester resin (B) was synthesized.
The weight average molecular weight (Mw) of the obtained crystalline polyester resin (B) was 23000 by molecular weight measurement (polystyrene conversion) by gel permeation chromatography. Further, when the melting point (Tm) of the crystalline polyester resin (B) was measured using a differential scanning calorimeter (DSC) by the above-described measuring method, it showed a clear endothermic peak, and the endothermic peak temperature was 68.4. ° C.

(Synthesis example 3) Preparation of carrier-coated crystalline polyester resin (C) In a heat-dried three-necked flask, 100 mol% of 1,10-dodecanedioic acid, 100 mol% of 1,9-nonanediol, and 100 parts by mass in total of these After adding 0.3 parts by mass of dibutyltin oxide as a catalyst, the air in the container was put into an inert atmosphere with nitrogen gas by depressurization, and the mixture was stirred and refluxed at 180 ° C. for 5 hours with mechanical stirring. Thereafter, the temperature was gradually raised to 230 ° C. under reduced pressure, and the mixture was stirred for 4 hours. When it became viscous, it was cooled with air, the reaction was stopped, and a crystalline polyester resin (C) was synthesized. The weight average molecular weight (Mw) of the obtained crystalline polyester resin (C) was 28000 by molecular weight measurement (polystyrene conversion) by gel permeation chromatography. Further, when the melting point (Tm) of the crystalline polyester resin (C) was measured by a differential scanning calorimeter (DSC) by the above-described measuring method, it showed a clear endothermic peak, and the endothermic peak temperature was 69.4. ° C.

(Synthesis example 4) Preparation of crystalline polyester resin (D) for carrier coating In a heat-dried three-necked flask, 100 mol% of adipic acid and 100 mol% of ethylene glycol, and dibutyltin oxide 0. After putting 3 parts by mass, the air in the container was brought into an inert atmosphere with nitrogen gas by depressurization, and stirred and refluxed at 180 ° C. for 5 hours with mechanical stirring. Thereafter, the temperature was gradually raised to 230 ° C. under reduced pressure, and the mixture was stirred for 2 hours. When it became viscous, it was air-cooled, the reaction was stopped, and a crystalline polyester resin (A) was synthesized. The weight average molecular weight (Mw) of the obtained crystalline polyester resin (A) was 15000 by molecular weight measurement (polystyrene conversion) by gel permeation chromatography. Further, when the melting point (Tm) of the crystalline polyester resin (A) was measured by a differential scanning calorimeter (DSC) by the above-described measuring method, it showed a clear endothermic peak, and the endothermic peak temperature was 72.2. ° C.

(Synthesis Example 5) Preparation of carrier-coated amorphous polyester resin (amorphous resin) (E) Terephthalic acid 100 mol%, isophthalic acid 20 mol%, bisphenol A propylene oxide 2 mol adduct 90 mol%, ethylene glycol 10 mol% In a 5 liter flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and rectifying column, the reaction system is heated to 190 ° C over 1 hour, and the reaction system is stirred uniformly. After confirming the above, 1.2 parts by mass of dibutyltin oxide was added. Further, 6 hours from the same temperature was required while distilling off the generated water, the temperature was raised to 240 ° C., and the dehydration condensation reaction was continued at 240 ° C. for another 5 hours to obtain an amorphous polyester resin (E).
The acid value of the amorphous polyester resin (E) was 10.0 mg / KOH, the molecular weight was measured by gel permeation chromatography (in terms of polystyrene), and the obtained weight average molecular weight was 25,000. When this resin was measured using a differential scanning calorimeter (DSC), it did not show a clear endothermic peak, had a glass transition temperature of 75.3 ° C., and was confirmed to be an amorphous resin.

(Preparation of amorphous resin) Amorphous resin for carrier coating (Amorphous resin) (F)
As an amorphous resin, a styrene-methyl methacrylate copolymer (component ratio 30:70) was prepared. The weight average molecular weight obtained by gel permeation chromatography (polystyrene conversion) was 81,000, and when measured using a differential scanning calorimeter (DSC), it showed no clear endothermic peak, and the glass transition temperature was It was 84 degreeC and it was confirmed that it is an amorphous resin.

<Creation of carrier>
1. Production of carrier 1 (this embodiment product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin A 0.5 parts Amorphous polyester resin E 2.0 parts Crosslinked melamine resin particles 0.20 parts (average particle Diameter: 0.3μm, ethyl acetate insoluble)

First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, the coating layer forming solution and the ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 1. did.
The obtained carrier 1 was 7.8 × 10 ¹¹ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 78.0 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 65.8 ° C., and TmA-TmAB was 12.2 ° C.

2. Production of carrier 2 (this embodiment product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin B 0.5 parts Amorphous polyester resin E 2.0 parts Crosslinked melamine resin particles 0.20 parts (average particle Diameter: 0.3μm, ethyl acetate insoluble)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, this coating layer forming solution and ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 2. did.
The obtained carrier 2 was 2.6 × 10 ¹³ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin B is 68.5 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 62.7 ° C., and TmA-TmAB was 5.8 ° C.

3. Production of carrier 3 (this embodiment product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin C 0.5 parts Amorphous polyester resin E 2.0 parts Crosslinked melamine resin particles 0.20 parts (average particle Diameter: 0.3μm, ethyl acetate insoluble)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, this coating layer forming solution and ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 3. did.
The obtained carrier 3 was 4.7 × 10 ¹³ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin C is 72.0 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 63.2 ° C., and TmA-TmAB was 8.8 ° C.

4). Production of carrier 4 (this embodiment product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin A 0.75 parts Amorphous polyester resin E 1.75 parts Crosslinked melamine resin particles 0.20 parts (average particle Diameter: 0.3μm, ethyl acetate insoluble)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, the coating layer forming solution and ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 4. did. The obtained carrier 4 was 5.8 × 10 ⁰⁹ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 78.0 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 73.8 ° C., and TmA-TmAB was 4.2 ° C.

5). Production of carrier 5 (this embodiment product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin A 0.25 parts Amorphous polyester resin E 2.25 parts Crosslinked melamine resin particles 0.20 parts (average particle Diameter: 0.3μm, ethyl acetate insoluble)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, the coating layer forming solution and ferrite particles are placed in a vacuum degassing kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 5. did.
The obtained carrier 5 was 7.3 × 10 ¹³ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 78.0 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 61.3 ° C., and TmA-TmAB was 16.7 ° C.

6). Production of carrier 6 (this embodiment product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin A 0.25 parts Amorphous polyester resin E 2.25 parts Crosslinked methyl methacrylate resin particles 0.20 parts ( (Average particle size: 0.3μm, insoluble in ethyl acetate)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, this coating layer forming solution and ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 6. did.
The obtained carrier 6 was 2.7 × 10 ¹³ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 79.5 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 62.1 ° C., and TmA-TmAB was 17.4 ° C.

7). Production of carrier 7 (this embodiment product)
・ Ferrite particles (average particle size: 35 μm) 100 parts ・ Ethyl acetate 14 parts ・ Crystalline polyester resin A 0.15 parts ・ Styrene-methyl methacrylate copolymer 2.35 parts
(Copolymerization ratio 30:70)
・ 0.20 parts of crosslinked methyl methacrylate resin particles (average particle size: 0.5 μm, insoluble in ethyl acetate)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, this coating layer forming solution and ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 7. did.
The obtained carrier 7 was 8.9 × 10 ¹³ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 79.5 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 73.5 ° C., and TmA-TmAB was 6.0 ° C.

8). Production of carrier 8 (this embodiment product)
・ Ferrite particles (average particle size: 35 μm) 100 parts ・ Ethyl acetate 14 parts ・ Crystalline polyester resin A 0.5 part ・ Amorphous polyester resin E 2.2 parts

First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, this coating layer forming solution and ferrite particles are put into a vacuum degassing kneader, stirred at 60 ° C. for 30 minutes, further depressurized while warming, degassed, and dried to produce carrier 8. did.
The obtained carrier 8 was 3.2 × 10 ¹² Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 76.7 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 64.8 ° C., and TmA-TmAB was 11.9 ° C.

9. Manufacture of carrier 9 (comparative product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Amorphous polyester resin E 2.50 parts Crosslinked melamine resin particles 0.20 parts (average particle size: 0.3 μm, ethyl acetate insoluble)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, this coating layer forming solution and ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 9. did.
The obtained carrier 9 was 6.5 × 10 ¹⁵ Ω · cm when an electric field of log E = 4.0 V / cm was applied.

10. Manufacture of carrier 10 (comparative product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin A 1.25 parts Amorphous polyester resin E 1.25 parts Crosslinked melamine resin particles 0.40 parts (average particle Diameter: 0.3μm, ethyl acetate insoluble)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, this coating layer forming solution and ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 10. did.
The obtained carrier 10 was 8.3 × 10 ⁰⁸ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 78.0 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 75.6 ° C., and TmA-TmAB was 2.4 ° C.

11. Production of carrier 11 (comparative product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin D 0.50 parts Amorphous polyester resin E 2.0 parts Crosslinked melamine resin particles 0.25 parts (average particle Diameter: 0.3μm, ethyl acetate insoluble)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, the coating layer forming solution and the ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce carrier 11. did.
The obtained carrier 11 was 8.8 × 10 ⁰⁷ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 83.0 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 58.3 ° C., and TmA-TmAB was 24.7 ° C.

12 Production of carrier 12 (comparative product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin A 0.5 parts Styrene-methyl methacrylate copolymer F 2.0 parts Crosslinked melamine resin particles 0.20 parts ( (Average particle size: 0.3μm, insoluble in ethyl acetate)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, the coating layer forming solution and the ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce the carrier 12. did.
The obtained carrier 12 was 7.8 × 10 ¹³ Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 78.0 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 76.5 ° C., and TmA-TmAB was 1.5 ° C.

13. Production of carrier 13 (comparative product)
Ferrite particles (average particle size: 35 μm) 100 parts Ethyl acetate 14 parts Crystalline polyester resin A 0.35 parts Amorphous polyester resin E 2.0 parts Carbon black (R330: manufactured by Cabot) 15 parts ・ Cross-linked melamine resin particles 0.20 parts (average particle size: 0.3 μm, insoluble in ethyl acetate)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, the coating layer forming solution and the ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce the carrier 13. did.
The obtained carrier 13 was 4.5 × 10 ¹² Ω · cm when an electric field of log E = 4.0 V / cm was applied. The endothermic peak temperature TmA of the crystalline polyester resin A is 78.0 ° C., and a solution obtained by dissolving the crystalline polyester resin A and the amorphous polyester resin D mixed at a coating ratio on the carrier with ethyl acetate is dried. The endothermic peak temperature TmAB of the crystalline resin-derived component of the uploaded resin composition was 63.4 ° C., and TmA-TmAB was 14.6 ° C.

14 Manufacture of carrier 14 (comparative product)
・ Ferrite particles (average particle size: 35 μm) 100 parts ・ Ethyl acetate 14 parts ・ Styrene-methyl methacrylate copolymer F 2.0 parts ・ Carbon black (R330: manufactured by Cabot Corporation) 0.15 parts ・ Cross-linked melamine resin particles 0 20 parts (average particle size: 0.3 μm, insoluble in ethyl acetate)
First, a coating layer forming solution was prepared in which all components except the ferrite particles among the above components were dispersed by a sand mill. Next, the coating layer forming solution and the ferrite particles are put into a vacuum degassing type kneader, stirred at 60 ° C. for 30 minutes, further depressurized while being heated, degassed, and dried to produce a carrier 14. did.
The obtained carrier 14 was 2.6 × 10 ¹² Ω · cm when an electric field of log E = 4.0 V / cm was applied.

<Manufacture of color toner>
(Adjustment of resin particle dispersion)
280 parts of styrene, 120 parts of n-butyl acrylate, 6 parts of acrylic acid, and 8 parts of dodecanethiol were mixed and dissolved in 6 parts of a nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) and anion Anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was emulsion-polymerized in a flask in which 550 parts of ion-exchanged water was dissolved, and 4 parts of ammonium persulfate was dissolved in this while slowly mixing for 10 minutes. 50 parts of ion-exchanged water was added. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin particle dispersion in which resin particles of 210 nm, Tg = 53 ° C., and weight average molecular weight Mw = 33000 were dispersed was obtained.

[Adjustment of cyan colorant dispersion]
C. I. Pigment Blue 15: 3, 100 parts (manufactured by Dainichi Seika Co., Ltd .: Seika Fast Yellow 2054), anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 10 parts, ion-exchanged water, 390 parts are mixed and dissolved. Then, the mixture was dispersed for 10 minutes using a homogenizer (manufactured by IKA: Ultra Tarrax) to prepare a cyan colorant dispersion. The volume average particle diameter D50v was 151 nm.
[Magenta Colorant Dispersion Adjustment]
By adjusting the cyan colorant dispersion, the colorant was changed to magenta R122 pigment (manufactured by Dainichi Seika Co., Ltd .: ECR
A magenta colorant dispersion was obtained in the same manner except that it was changed to -186Y). Volume average particle diameter D
50v was 121 nm.

[Preparation of yellow colorant dispersion]
A yellow colorant dispersion was obtained in the same manner except that the colorant was changed to yellow Y74 pigment (manufactured by Clariant Japan, Inc .: Hansa Brill. Yellow 5GX03) by adjusting the cyan colorant dispersion. The volume average particle diameter D50v was 138 nm.

[Adjustment of black colorant dispersion]
A black colorant dispersion was obtained in the same manner except that the colorant was changed to carbon black (manufactured by Cabot: Regal 330) by adjusting the cyan colorant dispersion. The volume average particle diameter D50v was 105 nm.

<Preparation of release agent dispersion>
Polyalkylene wax (FNP0092, Nippon Seiwa Co., Ltd., melting point 91 ° C.) 45 parts by weight Cationic surfactant Neogen RK (Daiichi Kogyo Seiyaku Co., Ltd.) 5 parts by weight Ion-exchanged water 200 parts by weight After sufficiently dispersing with IKA Ultra Turrax T50, it is dispersed with a pressure discharge type gorin homogenizer, and has a volume average particle size of 190 nm and a solid content of 24.
A 3% by weight release agent dispersion was obtained.

(Adjustment of color toner base particles)
-Resin particle dispersion (obtained above) 234 parts-Colorant dispersion (YMCK) 30 parts-Release agent dispersion 40 parts-Polyaluminum hydroxide (Ahoda Chemical Co., Paho2S) 0.5 part 600 parts of ion-exchanged water The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then stirred in the oil bath for heating. Heated to 40 ° C. After maintaining at 40 ° C. for 30 minutes, it was confirmed that aggregated particles having a D50 of 4.5 μm were produced. Further, the temperature of the heating oil bath was raised and maintained at 56 ° C. for 1 hour, and D50 was 5.3 μm. Thereafter, 26 parts by weight of the resin particle dispersion was added to the dispersion containing the aggregate particles, and then the temperature of the heating oil bath was raised to 50 ° C. and held for 30 minutes. The dispersion containing the aggregated particles was added with 1N sodium hydroxide to adjust the pH of the system to 7.0, and then the stainless steel flask was sealed and heated to 80 ° C. while continuing stirring using a magnetic seal. And held for 4 hours. After cooling, the toner base particles were filtered off, washed four times with ion exchange water, and then lyophilized to obtain toner base particles. The toner base particle K1 had a D50 of 5.9 μm and an average shape factor ML2 / A of 132.

<Manufacture of transparent toner>
Transparent toner base particles were obtained in the same manner except that the colorant dispersion (YMCK) was not added.
<Adjustment of transparent developer>
The carrier shown in Table 1 below was mixed with the obtained transparent toner in a ratio of 100 parts: 8 parts by a 2 liter V blender, and Examples 1 to 5 and Comparative Examples 1 to 6 were mixed. An electrostatic latent image developer was prepared.

<Evaluation of developer>
First, a rectangular solid image having a size of 15 mm × 20 mm was formed by the image forming apparatus [Apeos Port II-C4300 (manufactured by Fuji Xerox Co., Ltd.)] using the color toner.
Thereafter, a transparent development is performed on the surface of the solid image with the color toner using a transparent developer in an environment of normal temperature and normal humidity (22 ° C., 55% RH) by a gloss applying device having the same configuration as shown in FIG. An image made of an agent was formed, and gloss was imparted. Continuous image formation and glossing were performed, and the 100th (initial) image was evaluated for solid image end omission, transparent image area blurring, and overall image quality evaluation according to the following criteria. The results are shown in Table 1 below.

(1) Solid image edge missing A rectangular solid image having an image density of 1.5 and a size of 15 mm × 20 mm was prepared, and the degree of white void at the edge of the image was visually evaluated. Specific evaluation criteria are as follows. ○ and Δ are evaluated as having no practical problem.
○: Cannot be recognized visually.
Δ: Slightly recognized visually.
×: Remarkably visible.
(2) Transparent image area Kusumi evaluation Using a magnifying glass or a microscope on the image blank paper area (the area where the transparent toner image is formed but the color image is not formed), count the colored foreign matter per 1 cm ² , and the following criteria It was evaluated with.
○: Less than 50 colored foreign matters Δ: From 50 to 500 colored foreign matters ×: More than 500 colored foreign matters

(3) Comprehensive image quality In Examples and Comparative Examples, after color images and gloss were imparted, the overall evaluation of the finally obtained images was sensory evaluated according to the following evaluation criteria. The sensory evaluation was performed by 10 people.
Highly preferred: 5 points preferred: 4 points normal: 3 points unfavorable: 2 points highly unfavorable: 1 point The above evaluation was performed on 10 evaluators, and the following evaluation was made based on the average score of 10 points. Based on the criteria, the overall image quality was evaluated. ○ and Δ are evaluated as having no practical problem.
○: 3.5 points or more Δ: 2.5 ° C or more and less than 3.5 points ×: less than 2.5 points

(4) Charge maintenance property The charge maintenance property was evaluated as follows.
About 20 g of the developer at the initial stage and after 30,000 sheets was sampled and blown off to remove the toner from the developer, and only the carrier was isolated. To the obtained carrier, 0.5 g of the toner used for producing the developer was newly added to 10 g of the carrier, and stirred for 5 minutes with a turbula mixer to measure the charge amount.
The ratio between the initial developer and the carrier charge amount after 50,000 sheets (charge ratio after 50,000 sheets with respect to the initial) was calculated and evaluated. The evaluation criteria for the charge maintenance property are as shown below.
○: Charge amount ratio is 1.0 ± 0.2
Δ: Charge amount ratio is over 0.6 and less than 0.8 or over 1.2 and less than 1.4 ×: Charge amount ratio is 0.6 or less or 1.4 or more

As is clear from Table 1, the transparent developers of Examples 1 to 8 were superior in charge retention compared to the comparative example, and an image imparted with gloss using the developer was obtained in the comparative example. Compared with the image, it can be seen that the color toner image has less color dullness and image omission, and a high quality image is formed.
This embodiment is carried out by selecting a crystalline polyester resin and an amorphous resin having predetermined compatibility based on the comparison between Examples 1, 4 and 5 and Comparative Examples 2 and 5, and adjusting the content ratio. It can be seen that the carrier resistance value specified in the form is achieved, and a developer exhibiting excellent effects can be obtained.

DESCRIPTION OF SYMBOLS 1 Document 2 Illumination 3 Color scanner 4 Image processing apparatus 5 Laser diode 6 Optical system 7 Charger 8 Organic photoreceptor 9 Yellow developing device 10 Magenta developing device 11 Cyan developing device 12 Black developing device 13 Intermediate transfer belt 14 Transfer corotron 15 and 16 Transfer roll 17 Recording medium 19 Conveying device 20 Transparent toner image holder 21 Transparent toner image forming means 22 Heating and pressing means 23 Heat sink (cooling means)
24 Photosensitive drum 25 Charging device 26 Exposure device 27 Transparent toner image signal forming device 28 Transparent toner image developing device 29 Transfer device 30 Heating roll (transfer fixing means)
31 Pressure roll (transfer fixing means)
32 peeling roll 33 driven roll 34 transparent toner image 35 color toner image

Claims (6)

The carrier contains a transparent toner, and the carrier has a core material and a coating layer containing at least the crystalline polyester resin A and the amorphous resin B, and the volume resistance at the time of compression is logE = 4.0 V / cm. A developer for developing an electrostatic charge image that is 1.0 × 10 ⁹ Ω · cm or more and 1.0 × 10 ¹⁴ Ω · cm or less when an electric field is applied. The endothermic peak temperature derived from the crystalline polyester resin A contained in the carrier coating layer is TmA (° C.), and the endothermic peak temperature derived from the crystalline polyester resin A and the amorphous resin B in the mixture of the crystalline polyester resin A and TmAB The developer for electrostatic image development according to claim 1, wherein TmA (° C.) and TmAB (° C.) satisfy the relationship of the following formula (1).
5 <TmA-TmAB <20 (1)   The mixing ratio (A / B) of the crystalline polyester resin A and the amorphous resin B contained in the coating layer of the carrier is in the range of 1/99 to 40/60 in terms of mass. 2. The developer for developing an electrostatic charge image according to 2.   The developer for electrostatic image development according to any one of claims 1 to 3, wherein the coating layer of the carrier contains crosslinked resin particles that impart a negative chargeability to the transparent toner.   The endothermic peak temperature [TmA (° C.)] derived from the crystalline polyester resin A contained in the coating layer of the carrier is 50 ° C. or higher and 100 ° C. or lower. 5. Developer for charge image development. The color toner image containing a thermoplastic resin and a colorant is used to form a color toner image on the surface of the recording medium by an electrophotographic method, and then the color toner image is surrounded by any one of claims 1 to 5. A gloss imparting device that imparts gloss to an image by transferring and fixing the developer for developing an electrostatic image described in the above,
A transparent toner image holding member for holding a transparent toner image, and a transparent toner image comprising the developer for developing an electrostatic charge image according to any one of claims 1 to 5 on the surface of the transparent toner image holding member. The transparent toner image forming means to be formed and the transparent toner image formed on the surface of the transparent toner image holding member are transferred to the surface on which the color toner image is formed on the surface of the recording medium and fixed by heating and pressing. Heating and pressing means, and after cooling the transparent toner image and the color toner image transferred and fixed on the surface of the recording medium, the recording medium on which the transparent toner image and the color toner image are formed is peeled from the transparent toner image holding member. And a cooling and peeling means.