JP6330362B2 - Image forming apparatus, toner set, developer, image forming method, and process cartridge - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, an image forming method using the image forming apparatus, a toner set used in the image forming apparatus, a developer, and a process cartridge.

In recent years, in image forming apparatuses such as copiers, printers, facsimiles, etc., in the product printer field, high gloss image quality has been achieved using transparent toner in response to the needs of users using various paper types and high gloss image quality. The demand for an image forming system capable of forming an image is increasing year by year.
However, when a transparent toner that does not contain a colorant and a colored toner that contains a colorant are simultaneously formed, there arises a problem that uniformity of image color characteristics is deteriorated and uneven glossiness is deteriorated. In particular, in an image forming system in which a transparent image is provided on a color image, there is a tendency that the uniformity of image color characteristics is reduced and the problem of uneven gloss is more likely to occur.

  Because these problems pass through the fixing mechanism in a state where the transparent toner is further superimposed on the color toner, and the presence or absence of the colorant and the resin that can be contained are different between the color toner and the transparent toner. This is because the color toner and the transparent toner have different melting states at the time of fixing.

If the transparent toner in the upper layer of the image is too much dissolved than the colored toner in the lower layer, the transparent toner on the outermost layer of the image becomes thread-drawn when the image is peeled off from the fixing belt, and gloss unevenness occurs on the image surface. In addition, when the transparent toner in the upper layer of the image is less soluble than the colored toner in the lower layer, the transparent toner has insufficient spreadability, and light absorption at a specific wavelength (absorption peak at 400 to 600 nm) occurs partially depending on the location. The uniformity of the color characteristics of the entire image is reduced.
Therefore, it is necessary to satisfy both the user's need for a high gloss transparent toner and the prevention or suppression of color toner color characteristic uniformity deterioration due to the use of the transparent toner and image quality deterioration due to gloss unevenness. To satisfy this, it is important how the colored toner and the transparent toner can be fused in the same state at the time of fixing.

  As a conventional means, in order to control the melting state of the toner, the fixing temperature is changed and the thermal energy is adjusted. However, only by changing the fixing temperature, the difference between the melting state of the transparent toner and the melting state of the colored toner cannot be sufficiently reduced, and further improvement has been demanded.

On the other hand, in order to improve the releasability of the toner when the image is peeled off from the fixing belt, various methods for facilitating the release agent to ooze out on the toner surface have been studied.
However, simply improving the releasability cannot achieve the same melting state of the transparent toner and the colored toner, and does not satisfy the user's request.

In addition, instead of the styrene-acrylic resin that has been widely used for the purpose of improving the low temperature fixability, attempts have been made to use a polyester resin that has excellent low temperature fixability and relatively good heat storage stability (for example, patents). See references 1-6.) In addition, there is an attempt to add a specific non-olefinic crystalline polymer having sharp melt properties at the glass transition temperature in the binder resin (see, for example, Patent Document 7), and an effect of improving low-temperature fixability is recognized. .
However, none of the above-mentioned patent documents 1 to 7 has reached the same melting level of the transparent toner and the colored toner.

  Furthermore, in the technique described in Patent Document 8, a sea-island-like phase separation structure formed by an incompatible crystalline polyester resin and an amorphous polyester resin, and thermal characteristics by differential scanning calorimetry of the resin are specified. Therefore, both low-temperature fixability and heat-resistant storage stability are achieved. However, although the effect of improving the low-temperature fixing property is recognized, the melting degree of the transparent toner and the colored toner has not been made the same.

  Furthermore, in the technique described in Patent Document 9, when a toner containing a large amount of crystalline polyester resin is used in a high-speed machine, toner filming occurs, and the image quality is not sufficiently reliable. The above problem occurs.

Conventionally, in image forming apparatuses such as copying machines and printers, fixing devices using a fixing roller having a heater and a pressure roller are widely used as means for fixing a toner image on paper.
This heater heats the nip where the fixing roller and the pressure roller are in contact with each other and heats and fixes the toner adhering to the paper passing through the nip to obtain a fixed image.
As a configuration of the fixing roller or belt, a heat storage layer is formed on the base material layer, and a material having a large heat capacity and a high heat transport amount is suitable as the heat storage layer. Further, a configuration in which a release layer is further provided is known, but the melting state of the transparent toner and the color toner has not been made the same.

As described above, raising the fixing temperature or simply adding a crystalline polyester resin to the toner can improve the low-temperature fixability. However, in a high-gloss image forming system using transparent toner, it has not yet been possible to prevent the problem of uneven color characteristics and gloss unevenness that occur when the colored toner layer and the transparent toner layer are melted differently at the time of fixing.
In recent years, there has been an increasing need to use thick paper and uneven paper in product printers in the industrial and advertising fields, but when forming images with thick paper and uneven paper, existing image forming devices have more uniform color characteristics than thin paper. There has been a problem that the toner is liable to be deteriorated and toner gloss unevenness is likely to occur.

  The present invention has been made in view of the above-described problems in the prior art, and can suppress a decrease in color characteristic uniformity and toner gloss unevenness that occur during fixing. It is an object of the present invention to provide an image forming apparatus capable of suppressing a decrease in uniformity of color characteristics and toner gloss unevenness that occur at the time.

In order to solve the above problems, an image forming apparatus according to the present invention includes a color image forming unit that forms a color image on a recording medium using one or more colored toners, and a color formed by the color image forming unit. A transparent image forming means for forming a transparent image on the image using a transparent toner, and a fixing means for fixing the color image and the transparent image carried on the recording medium to the recording medium, Each of the transparent toner and the colored toner contains a release agent and a binder resin, and the binder resin includes a crystalline polyester resin and an amorphous resin, and includes a Fourier transform infrared spectroscopic analyzer. W is the height of the maximum rising peak point in the infrared absorption spectrum of the crystalline polyester resin obtained by infrared spectroscopy (KBr total transmission method) using W, and the amorphous resin When the height of the maximum rising peak point in the infrared absorption spectrum is R, and the ratio W / R is X1 for the colored toner and X2 for the transparent toner, both of the following formulas 1 and 2 are satisfied. To do.
0 ≦ X2-X1 ≦ 0.75 Formula 1
0.05 ≦ X2 ≦ 0.80 Expression 2

  According to the present invention, it is possible to suppress color characteristic uniformity degradation and toner gloss unevenness that occur during fixing, and even when fixing on thick paper and uneven paper, color characteristic uniformity degradation and toner gloss unevenness that occur during fixing. It is possible to provide an image forming apparatus capable of suppressing the above-described problem.

3 is a graph showing an example of an infrared absorption spectrum of a crystalline polyester resin that is a component of a transparent toner used in the present invention. 3 is a graph showing an example of an infrared absorption spectrum of an amorphous polyester resin that is a component of a transparent toner used in the present invention. 1 is a schematic front view of an image forming apparatus to which the present invention is applied. FIG. 4 is a schematic front sectional view of a fixing belt used in a fixing device provided in the image forming apparatus shown in FIG. 3.

An image forming apparatus according to the present invention includes: a color image forming unit that forms a color image on a recording medium using one or more colored toners; and a color image forming unit formed on the color image forming unit. A transparent image forming means for forming a transparent image using the transparent toner, and a fixing means for fixing the color image and the transparent image carried on the recording medium to the recording medium. Each of the colored toner contains a release agent and a binder resin, and the binder resin contains a crystalline polyester resin and an amorphous resin, and uses a Fourier transform infrared spectrometer. The height of the maximum rising peak point in the infrared absorption spectrum of the crystalline polyester resin obtained by infrared spectroscopy (KBr total transmission method) was W, and the infrared absorption of the amorphous resin was The height of the maximum rising peak point in the spectrum and R, these ratios W / R color toner is X1, when the transparent toner is a X2, and satisfies both of the following formulas 1 and 2.
0 ≦ X2-X1 ≦ 0.75 Formula 1
0.05 ≦ X2 ≦ 0.80 Expression 2

Next, the image forming apparatus according to the present invention will be described in more detail.
Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

By satisfying the above conditions, the use of a crystalline polyester resin having only a melting point (no Tg) reduces the uniformity of color characteristics even in an image forming apparatus having a transparent toner layer on a colored toner. Further, it is possible to provide an image forming apparatus in which the problem of uneven glossiness does not occur.
Although the mechanism of the effect is not clear, the fixing mechanism makes it easy for the crystalline polyester to ooze out evenly from the upper and lower toner layers, and it is not a factor that the colored toner and the transparent toner layer are in a close melting state. It is estimated that. This occurs when a crystalline polyester resin having only a melting point (not having Tg) satisfies the specified range and the specified formula of the present invention for a colored toner and a transparent toner.
In addition, by using colored toners and transparent toners that satisfy the specified range and formula in the present invention, thermal energy is used when fixing the toner layer on the recording medium with a fixing mechanism, even in the case of thick paper and uneven paper. It is assumed that the toner can be spread over the entire toner layer. For this reason, even in the case of thick paper and concavo-convex paper, it is possible to suppress color characteristic uniformity degradation and toner gloss unevenness that occur during fixing.

Hereinafter, in the image forming apparatus 100 according to the present invention, an embodiment of toner (transparent toner, colored toner) to which the present invention is used for image formation will be described.
First, a basic configuration of such toner (transparent toner, colored toner) will be described.

Each of the transparent toner and the colored toner used in the present invention contains a release agent and a binder resin, and the binder resin contains a crystalline polyester resin and an amorphous resin.
The height of the maximum rising peak point in the infrared absorption spectrum of the crystalline polyester resin obtained by infrared spectroscopy (KBr total transmission method) using a Fourier transform infrared spectrometer is W, the amorphous When the height of the maximum rising peak point in the infrared absorption spectrum of the photosensitive resin is R and the ratio W / R is X1 for the colored toner and X2 for the transparent toner, both of the following formulas 1 and 2 are satisfied.

0 ≦ X2-X1 ≦ 0.75 Formula 1
0.05 ≦ X2 ≦ 0.80 Expression 2

The crystalline polyester resin of the transparent toner and the colored toner is crystallized from an absorbance spectrum obtained by KBr method (total transmission method) measurement by “Avatar 370 / Thermo Electron Co., Ltd.” with FT-IR (Fourier transform infrared spectroscopic measurement device). The peak height of the characteristic spectrum of the crystalline polyester resin is W, and the peak height of the characteristic spectrum of the amorphous resin is R, and the crystalline polyester resin peak ratio indicated by W / R is obtained. In the case of W / R colored toner, X1 and in the case of transparent toner, X2. X2 is preferably 0.05 to 0.80, more preferably 0.09 to 0.40.
It is important that the crystalline polyester resin peak ratio X2 represented by W / R is 0.05 to 0.80. When X2 is smaller than 0.05, the crystalline polyester resin is less likely to ooze out from the inside of the toner at the time of fixing, and it is difficult to adjust the melting condition of the transparent toner and the colored toner. It becomes easy for the uniformity of color characteristics to decrease due to incomplete melting. If X2 is greater than 0.80, the crystalline polyester resin will ooze out of the toner surface by the image formation mechanism before reaching the fixing process, contaminating the carrier and in-machine paper transport rollers, shortening the part life. Cause problems.

In the W / R, when the color toner is X1 and the transparent toner is X2, it is important to satisfy the above formulas 1 and 2.
Here, it is preferable that X2-X1 is 0.00-0.75, and it is more preferable that X2-X1 is 0.04-0.35.
When X2-X1 is greater than 0.75, the transparent toner is more soluble than the colored toner, and image surface gloss unevenness due to toner stringing tends to occur when the transparent toner is peeled off from a fixing member such as a fixing belt.
When X2−X1 is smaller than 0 (negative value), the transparent toner is not completely melted than the colored toner, the spreadability is insufficient, and the color characteristic uniformity of the colored toner layer under the image is likely to be lowered.

  Such control of the resin peak ratio represented by W / R is considered to be determined by the compatibility state of the crystalline polyester resin with the amorphous resin. However, it is difficult to measure the crystallinity. Therefore, in the present invention, the manufacturing conditions such as each manufacturing process including the transparent toner and the colored toner prescription raw material ratio and the emulsification are optimized by a quality engineering technique, and the relationship of the W / R is expressed by the above formula 1. If the formulation and production conditions satisfy the requirements (2) and (2), it can be achieved intentionally and reliably. In other words, the technical key point of the present invention is to find the optimum formulation and manufacturing conditions so as to control the compatibility state of the crystalline polyester resin and the amorphous resin in consideration of the balance of quality problems. There is also a point.

<Measurement method of crystalline polyester resin peak ratio represented by W / R>
The crystalline polyester resin peak ratio on the toner surface is determined from the peak intensity ratio known from the KBr spectrum by the KBr method (total transmission method) using FT-IR (Fourier transform infrared spectroscopic measurement device).

In the present invention, the peak height of the characteristic spectrum (1165 cm ⁻¹ ) in the crystalline state of the crystalline polyester resin is W (FIG. 1, the height baseline is 1158-1201 cm ⁻¹ ), The peak height of a characteristic spectrum (for example, 829 cm ^{−1 in} the case of a polyester resin (FIG. 2, the height baseline is 784-889 cm ⁻¹ )) was calculated as R, and W / R was calculated as the peak intensity ratio. In the present invention, the peak intensity ratio is obtained by converting the spectrum to absorbance and using the peak height.

FIG. 1 shows an example of an infrared absorption spectrum of a crystalline polyester resin.
As shown in the figure, the infrared absorption spectrum of the crystalline polyester resin has a falling peak point at which the absorbance becomes the lowest between wave numbers 1130 cm ^{−1 to} 1220 cm ⁻¹ (hereinafter referred to as “first falling peak point Fp1”). ) And the falling peak point at which the absorbance is the second smallest (hereinafter referred to as “second falling peak point Fp2”), the maximum rising peak point Mp (Mp is 1183 cm ⁻ ) at which the absorbance is maximum. ¹ ).
A line segment connecting the first falling peak point Fp1 and the second falling peak point Fp2 is defined as a base line. Then, a vertical line is drawn from the maximum rising peak point Mp toward the horizontal axis, and the absolute value of the difference between the absorbance at the intersection with the baseline and the absorbance at the maximum rising peak point Mp is expressed as the height W of the maximum rising peak point Mp. And

FIG. 2 shows an example of an infrared absorption spectrum of an amorphous polyester resin.
As shown in the figure, the infrared absorption spectrum of the amorphous polyester resin has a maximum rising peak point Mp (Mp is 699 cm ⁻¹ ) and a minimum absorbance between wave numbers 780 cm ^{−1 to} 900 cm ⁻¹ . There are a first falling peak point Fp1 and a second falling peak point Fp2 where the absorbance is the second smallest, and the maximum rising peak point Mp is between the first falling peak point Fp1 and the second falling peak point Fp2. Located between. A line segment connecting the first falling peak point Fp1 and the second falling peak point Fp2 is defined as a base line. Then, a vertical line is drawn from the maximum rising peak point Mp toward the horizontal axis, and the absolute value of the difference between the absorbance at the intersection with the baseline and the absorbance at the maximum rising peak point Mp is expressed as the height of the maximum rising peak point Mp. Let R be. Moreover, let W / R be a peak ratio (W / R value).

[Toner (colored toner, transparent toner)]
Hereinafter, raw materials (toner materials) used for the colored toner containing a colorant and the transparent (not containing a colorant) transparent toner used in the present invention will be sequentially described.

  The transparent toner and the colored toner used in the present invention each contain a release agent and a binder resin, and the binder resin contains a crystalline polyester resin and an amorphous polyester resin.

(Binder resin)
<Amorphous polyester resin>
As the non-crystalline polyester resin, a well-known and conventional one can be used, but it is preferable to use a modified polyester containing at least an ester bond and a bond unit other than the ester bond. The binder resin precursor is a resin precursor capable of producing the modified polyester. The binder resin precursor preferably contains a compound having an active hydrogen group and a polyester having a functional group capable of reacting with the active hydrogen group of the compound. For example, when using a polyester [polyester prepolymer (A)] having an isocyanate group as a polyester having a functional group capable of reacting with an active hydrogen group, it can be produced by the following method.

  Polyol (1) and polycarboxylic acid (2) are produced by heating to 150 to 280 [° C.] in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and if necessary, reducing the pressure. Water is distilled off to obtain a polyester having a hydroxyl group. Next, the polyester having a hydroxyl group is reacted with a polyisocyanate (3) at 40 to 140 [° C.] to obtain a polyester prepolymer (A) having an isocyanate group [hereinafter abbreviated as “prepolymer (A)”. There is]. Further, (A) is reacted with amines (B), which are compounds having an active hydrogen group, at 0 to 140 [° C.] to obtain a polyester modified with a urea bond.

  Examples of the polyol (1) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol, triethylene glycol, Ethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol F, Bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the alicyclic diol; bisphenols Alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts, and the like, may be used in combination. Among them, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols (for example, bisphenol A ethylene oxide 2 mol adduct, bisphenol A propylene oxide 2 mol adduct, bisphenol A propylene oxide 3 mol adduct, etc.) ) And the like.

  Polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trivalent or higher phenols (phenol novolac, cresol novolac, etc.); Examples include alkylene oxide adducts of polyphenols. Two or more of these may be used in combination. Examples of the polycarboxylic acid (2) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid) Etc.), and two or more of them may be used in combination. Of these, alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms are preferable.

  Examples of the trivalent or higher polycarboxylic acid (2) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (trimellitic acid, pyromellitic acid, and the like). Two or more of these may be used in combination. In place of polycarboxylic acid, polycarboxylic acid anhydride or lower alkyl ester (methyl ester, ethyl ester, isopropyl ester, etc.) may be used.

  Polyisocyanate (3) includes an isocyanate agent. Examples of the amines (B) include those shown for the amines. When polyisocyanate (3) is reacted, or when prepolymer (A), amines and (B) are reacted, a solvent can be used as necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to the isocyanate (3), such as tetrahydrofuran (such as tetrahydrofuran).

<Crystalline polyester resin>
As described above, a crystalline polyester resin (hereinafter referred to as crystalline polyester (iii)) is contained as a binder resin for the base particles constituting the toner used in the present invention.
The crystalline polyester (iii) is obtained by reaction of an alcohol component and an acid component, and is a polyester having at least a melting point.

  The alcohol component of the crystalline polyester (iii) contains a diol compound having 2 to 6 carbon atoms, particularly 1,4-butanediol, 1,6-hexanediol and derivatives thereof, and the acid component includes It preferably contains at least one of maleic acid, fumaric acid, succinic acid, and derivatives of these acids. That is, a crystalline polyester having a repeating unit represented by the following general formula (1) synthesized from the alcohol component and the acid component is preferable.

(In the general formula (1), R ₁ and R ₂ are a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and n is a natural number.)

  Moreover, as a method for controlling the crystallinity and softening point of the crystalline polyester (iii), for example, a method of appropriately designing a molecular structure of a non-linear polyester or the like can be used. Such a non-linear polyester is condensed by adding a trihydric or higher polyhydric alcohol such as glycerin as an alcohol component and a trivalent or higher polyvalent carboxylic acid such as trimellitic anhydride as an acid component during polyester synthesis. It can be synthesized by polymerization.

The molecular structure of the crystalline polyester (iii) can be confirmed by solid NMR.
As for the molecular weight of the crystalline polyester (iii), since the molecular weight distribution is sharp and those having a low molecular weight are excellent in low-temperature fixability, the molecular weight distribution by GPC soluble in o-dichlorobenzene is indicated by the log (M) on the horizontal axis. In addition, it is preferable that the following conditions are satisfied in a molecular weight distribution diagram in which the vertical axis represents weight%. The preferable conditions are that the peak position is in the range of 3.5 to 4.0, the half width of the peak is 1.5 or less, the weight average molecular weight (Mw) is 1000 to 6500, and the number average molecular weight (Mn). 500 to 2000, and Mw / Mn is 2 to 5.
GPC is an abbreviation for Gel Permeation Chromatography.

The dispersed particle diameter in the base particles of the crystalline polyester (iii) used for the color toner and the transparent toner material in the present invention is 0.2 μm or more and 3.0 μm or less (0.2 to 3.0 μm) in the major axis diameter. It is preferable.
By controlling the major axis diameter of the dispersed particle diameter within the range of 0.2 to 3.0 μm, the fine dispersion of the special ester wax in the mother particle is further ensured, and the wax exudes to the surface of the mother particle through the fixing gap. The uneven distribution of wax at the time can be suppressed.

  The acid value of the crystalline polyester (iii) is preferably 8 mgKOH / g or more and 45 mgKOH / g or less. That is, from the viewpoint of the affinity between paper and resin, the acid value is preferably 8 mgKOH / g or more, more preferably 20 mgKOH / g or more in order to achieve the desired low-temperature fixability. In order to improve offset property, it is preferable that it is 45 mgKOH / g or less.

  Furthermore, the hydroxyl value of the crystalline polyester is from 0 mgKOH / g to 50 mgKOH (0 to 50 mgKOH / g), more preferably from 5 mgKOH / g, in order to achieve a predetermined low-temperature fixability and good charging characteristics. The thing of 50 mgKOH / g is preferable.

Moreover, in this invention, it is preferable that the endothermic peak temperature measured by the differential scanning calorimetry (DSC) of crystalline polyester resin is 50 degreeC or more and 150 degrees C or less. By setting it within this range, it is possible to suppress the deterioration of the uniformity of the color characteristics and the occurrence of the gloss unevenness problem.
When the temperature is less than 50 ° C., the color toner and the transparent toner have poor heat storage stability and are hardened during storage, resulting in poor fluidity.
When the temperature exceeds 150 ° C., the release agent is difficult to ooze out from the inside of the colored toner and the transparent toner at the time of fixing, the difference between the color toner and the transparent toner is likely to be dissolved, and the image surface gloss unevenness and the color characteristic reproduction deteriorate. Easy to be.

(Release agent)
In addition, as the release agent used for the colored toner and the transparent toner in the present invention, a well-known and conventional one can be used, but it is preferable to use an ester wax. In particular, it is preferable to use a synthetic ester wax. Furthermore, a monoester wax obtained from a long-chain linear saturated fatty acid and a long-chain linear saturated alcohol is preferable.
Use of these release agents is preferable because the color toner and the transparent toner have the same melting method in the fixing mechanism. Further, by using these release agents, when the toner and the synthetic ester wax in the toner are peeled off from the fixing belt, the release agent in the transparent toner on the outermost layer of the image oozes out on the toner surface and is fixed. Therefore, it is advantageous to avoid the uneven gloss that occurs in the image, and thus good image formation is possible.
Examples of the synthetic ester wax include a monoester wax synthesized from a long-chain linear saturated fatty acid and a long-chain linear saturated alcohol.

Long, straight-chain saturated fatty acid is represented by the general formula _C n _H 2n + 1 COOH, of about n = 5 to 28 is preferably used.
The long-chain linear saturated alcohol is represented by C _n H _{2n + 1} OH, and those with n = about 5 to 28 are preferably used.

Specific examples of long-chain linear saturated fatty acids include capric acid, undecyl acid, lauric acid, tridecyl acid, myristic acid, pentadecylic acid, palmitic acid, heptadecanoic acid, tetradecanoic acid, stearic acid, nonadecanoic acid, aramonic acid, Examples include behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, and melicic acid.
On the other hand, specific examples of the long-chain linear saturated alcohol include amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, Examples include pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, seryl alcohol, and heptadecane 1 ol.
The fatty acid and alcohol have a substituent such as a lower alkyl group, an amino group, or a halogen as long as they have a linear structure having 5 or more carbon atoms, so long as the effects of the present invention are not impaired. You may do it.

The monoester wax as described above is, for example, charged in a round bottom flask equipped with a stirrer and a condenser with 2 mol of a long chain linear saturated alcohol per 1 mol of a long chain linear saturated fatty acid, and added with a small amount of sulfuric acid to about 130 ° C. The mixture is heated at reflux for 4 hours, excess alcohol is removed, and the residue is purified with methyl ether or the like.
Another example of the synthetic ester wax is a triester wax synthesized from boric acid and a long-chain linear saturated alcohol.
As the boric acid, anhydrous boric acid or boron trichloride is used.
The boric acid triester is synthesized by, for example, adding 3 mol of a long-chain linear saturated alcohol to a round bottom flask equipped with a stirrer with respect to 1 mol of boric anhydride, and usually reacting at about 120 ° C. or higher.
Thereafter, the residue is obtained by purification with alcohol, ether or the like.

Furthermore, another example of the synthetic ester wax is an oligoester wax synthesized from a neopentyl type polyol, a dicarboxylic acid, and a long-chain linear saturated fatty acid.
Examples of the neopentyl polyol include neopentyl glycol, trimethylolpropane, pentaerythritol and the like.
Among these neopentyl type polyols, pentaerythritol has the best storage stability and is preferable.
Examples of dicarboxylic acids include aliphatic saturated dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid, and fatty acids such as maleic acid and fumaric acid. Aromatic dicarboxylic acids such as aromatic unsaturated dicarboxylic acids, phthalic acid, isophthalic acid and terephthalic acid.
Among these dicarboxylic acids, short-chain aliphatic dicarboxylic acids such as oxalic acid, malonic acid, maleic acid, and fumaric acid are preferable because the melting point is lowered and the fixing property is improved.
The oligoester wax was synthesized by putting neopentyl polyol, dicarboxylic acid and long-chain linear saturated fatty acid into a round bottom flask equipped with a stirrer and condenser, adding a small amount of sulfuric acid and heating to reflux at about 130 ° C. for 4 hours. Let
The residue is obtained by purifying with methyl ether or the like.

In the present invention, the ester wax preferably has an absorption heat peak temperature of 40 to 90 ° C. as measured by differential scanning calorimetry (DSC).
The lower the temperature, the better the low-temperature fixability. However, if the temperature is lower than 40 ° C., the storage stability of the transparent toner may be deteriorated.

Further, the content (weight ratio) of the release agent of the transparent toner and the colored toner of the present invention is preferably 1% or more and 20% or less with respect to the total amount of the base particles. With this range, when the image is peeled off from the fixing member such as a fixing belt, the release agent in the transparent toner on the outermost layer of the image oozes out on the toner surface, and it is advantageous to avoid uneven gloss that occurs during fixing. As a result, good image formation is possible. The base particles include a binder resin and a release agent, and the base particles and an external additive attached to the surface of the base particles constitute a toner (transparent toner, colored toner).
If it is less than 1%, the wax does not bleed out from the inside of the toner at the time of fixing, the image surface releasability of the colored toner and the transparent toner is inferior, and the surface of the image tends to be threaded when the fixing member is peeled off. Unevenness is likely to get worse.
If it exceeds 20%, the wax at the time of fixing is excessively oozed out from the toner surface, contaminating the in-machine paper transport roller and the like in the subsequent process, impairing the life of the parts, and causing problems.

  The melting point of the release agent is the temperature of the endothermic peak at which the endothermic amount becomes maximum in the differential heat curve obtained by differential scanning calorimetry (referred to as “maximum endothermic peak temperature”).

(Charge control agent)
If necessary, the toner may contain a charge control agent. As such a charge control agent, known ones can be used. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus Simple substance or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. Specifically, Nitronine-based dye Bontron 03, quaternary ammonium salt Bontron P-51, metal-containing azo dye Bontron S-34, oxynaphthoic acid metal complex E-82, salicylic acid metal complex E- 84, E-89 of a phenol-based condensate (manufactured by Orient Chemical Industry Co., Ltd.), TP-302 of a quaternary ammonium salt molybdenum complex, TP-415 (manufactured by Hodogaya Chemical Industry Co., Ltd.), quaternary ammonium Copy charge PSY VP2038 of salt, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit), copper phthalocyanine, perylene, quinacridone Azo pigments, sulfonate group, carboxyl group, and polymer compounds having a functional group such as a quaternary ammonium salt.

  The amount of charge control agent used is determined according to the type of binder resin, the presence or absence of additives (external additives) used as necessary, the toner production method including the dispersion method, and the like. . Although it cannot be limited uniquely, it is generally used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the main charge control agent is reduced, the electrostatic attractive force with the developing roller is increased, the flowability of the developer is reduced, and the image density is reduced. Incurs a decline. These charge control agents can be dissolved and dispersed after being melt-kneaded with a masterbatch or resin, and of course, they may be added directly when dissolved or dispersed in an organic solvent in the preparation process of the toner material liquid (oil phase). Alternatively, the matrix particles may be immobilized on the surface after the formation.

(Coloring agent)
Among the toners used in the present invention, the colored toner contains a colorant.
The colorant that can be used in the present invention is not particularly limited, and general dyes and pigments can be used.

  More specifically, for example, yellow colorants include C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 1, 2, 3, 5, 6, 49, 65, 73, 75, 97, 98, 111, 116, 130 and the like; C.I. I. Pigment Yellow 154, C.I. I. Benzimidazolone pigments such as Pigment Yellow 120, 151, 175, 180, 181, 194; I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, 95, 128, 166, etc. disazo condensation pigments; I. Pigment Yellow 110, C.I. I. Pigment Yellow 109 and other isoindolinone pigments; I. Pigment Yellow 147, C.I. I. Pigment Yellow 24, 108, 193, 199 and the like anthraquinone pigments; C.I. I. Pigment Yellow 12, 13, 14, 17, 55, 63, 81, 83, 87, 90, 106, 113, 114, 121, 124, 126, 127, 136, 152, 170, 171, 172, 174, 176, Disazo pigments such as 188; C.I. I. Pigment Yellow 61, 62, 133, 168, 169 and the like azo lake pigments; C.I. I. Pigment Yellow 139 and other isoindoline pigments; I. And quinophthalone pigments such as Pigment Yellow 138.

  Examples of magenta colorants include C.I. I. Pigment Red 146, C.I. I. Pigment Red 2, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 21, 22, 23, 31, 32, 95, 112, 114, 119, 136, Β-naphthol such as 147, 148, 150, 164, 170, 184, 187, 188, 210, 212, 213, 222, 223, 238, 245, 253, 256, 258, 261, 266, 267, 268, 269 Pigments; C.I. I. Pigment Red 57: 1, others include C.I. I. Pigment Red 18: 1, 48: 2, 48: 3, 48: 4, 48: 5, 50: 1, 51, 52: 1, 52: 2, 53: 1, 53: 2, 53: 3, 58: Azo lake pigments such as 2, 58: 4, 64: 1, 68, 200; I. Pigment Red 209, C.I. I. Pigment Red 122, 192, 202, 207, C.I. I. Quinacridone pigments such as Pigment Violet 19; I. Pigment Red 37, 38, 41, 111, C.I. I. Pigment Orange 13, 15, 16, 34, 44, etc. disazo pigments; C.I. I. Pigment Red 171, 175, 176, 185, 208, C.I. I. Pigment Violet 32, C.I. I. Benzimidazolone pigments such as Pigment Orange 36, 60, 62, 72; I. Pigment Red 144, 166, 214, 220, 221, 242, 248, 262, C.I. I. Disazo condensation pigments such as CI Pigment Orange 31; I. Dioxazine pigments such as Pigment Violet 23 and 37; I. Pigment Red 254, 255, 264, 272, C.I. I. And diketopyrrolopyrrole pigments such as Pigment Orange 71 and 73.

  Examples of the blue pigment include organic colorants such as bitumen, cobalt blue, alkali blue lake, Victoria blue lake, fast sky blue, indanthrene blue BC, ultramarine blue, phthalocyanine blue, and phthalocyanine green.

  Examples of the black pigment include organic colorants such as carbon black and aniline black.

  Further, green pigments such as chrome green, pigment green B, malachite green lake, and fanal yellow green G, and purple pigments such as manganese purple, fast violet B, and methyl violet lake can be used. Examples include various dyes such as acid, dispersion, and direct dyes, such as nigrosine, methylene blue, rose bengal, and quinoline yellow.

  By appropriately selecting the type of the colorant, each color toner such as yellow toner, magenta toner, cyan toner, black toner, and green toner can be obtained.

(External additive)
The toner is composed of base particles formed by particles (colored particles) granulated by solvent removal after emulsifying or dispersing a stock solution (oil phase) of toner material in an aqueous medium (aqueous phase). Is. An external additive may be added to the surface of the base particle for the purpose of assisting the fluidity, developability, chargeability, and cleanability of the toner having the base particle. As the external additive for assisting the fluidity, developability and chargeability of the base particles, inorganic fine particles are preferably used. The primary particle diameter of the inorganic fine particles is preferably 5 [nm] to 2 [μm], and particularly preferably 5 [nm] to 500 [nm]. The specific surface area of the toner having the base particles by the BET method is preferably ^{20 to} 500 [m ² / g]. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight of the toner, and particularly preferably 0.01 to 2.0% by weight.

  Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, Examples thereof include diatomaceous earth, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. In addition, polymer fine particles, for example, polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, dispersion polymerization, methacrylic acid ester, acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine, nylon, thermosetting Polymer particles made of a functional resin may be used.

  If necessary, the toner particles may be surface-treated with a fluidizing agent. As a result, the hydrophobicity can be increased, and deterioration of flow characteristics and charging characteristics can be prevented even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. It is done.

(Toner manufacturing method and used in manufacturing)
The toner according to one embodiment prepares a stock solution (oil phase) of a toner material by dissolving or dispersing a material containing at least a release agent and a binder resin and / or a binder resin precursor in an organic solvent. And the step of emulsifying or dispersing the stock solution in an aqueous medium (aqueous phase) and then removing the solvent to form base particles. By producing a transparent toner by this method, the crystalline polyester resin oozes out on the toner surface at the time of fixing, and it is possible to sufficiently reduce the uniformity of color characteristics and avoid the uneven gloss that occurs at the time of fixing. Is possible.
Hereinafter, an example of the manufacturing method will be described, but the present invention is not limited to this example.

  As the above-mentioned aqueous medium (aqueous phase), water alone may be used, but a solvent miscible with water may be used in combination. Examples of the miscible solvent include alcohol (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methylcellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.) and the like. Further, the aqueous medium (aqueous phase) may contain a dispersing agent such as a surfactant or a polymeric protective colloid as described later.

  When forming the base particles, when using polyester [polyester prepolymer (A)] having an isocyanate group as the binder resin precursor and amines (B), the polyester prepolymer (A) in an aqueous medium, The amine (B) may be reacted to give a modified polyester [urea-modified polyester: [modified polyester (i)]], or a modified polyester produced by previously reacting (A) and (B) [urea-modified polyester: [Modified polyester (i)] may be used.

  As a method for stably forming a dispersion comprising urea-modified polyester [modified polyester (i)] or polyester prepolymer (A) and amines (B) in an aqueous medium, a modified polyester ( i) or a composition of a toner material (raw material) containing a prepolymer (A) and an amine (B), another binder resin (crystalline polyester, etc.) and a release agent, and dispersed by shearing force The method etc. are mentioned.

  Polyester prepolymer (A) and other toner composition (hereinafter referred to as “toner raw material”) colorant (or colorant masterbatch), release agent, crystalline polyester, unmodified polyester, charge control agent These may be mixed when forming the dispersion in the aqueous medium, but it is more preferable to mix the toner raw material in advance and then add and disperse the mixture in the aqueous medium.

  On the other hand, when the unmodified polyester [unmodified polyester (ii)] is used in combination, (ii) is produced by the same method as the above polyester having a hydroxyl group, and this is a solution after completion of the reaction of (i). Dissolve in and mix.

  Toner raw materials such as a charge control agent are not necessarily mixed when forming particles in an aqueous medium, and may be added after the particles are formed. For example, after forming particles not containing a colorant, the colorant can be added by a known dyeing method.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. In order to make the particle diameter of the dispersion 2 to 20 [μm], a high-speed shearing method is preferable. When a high-speed shearing disperser is used, the number of rotations is not particularly limited, but is usually 1000 to 30000 [rpm], preferably 5000 to 20000 [rpm]. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 [° C.] (under pressure), preferably 40 to 98 [° C.]. Higher temperatures are preferred in that the dispersion made of urea-modified polyester [modified polyester (i)] or polyester prepolymer (A) has a low viscosity and is easily dispersed.

The amount of the aqueous medium used is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts per 100 parts by weight of the toner material (toner composition) containing the modified polyester (i) or polyester prepolymer (A) and amines (B). Parts by weight. When the amount of the aqueous medium used is less than 50 parts by weight, the toner composition is not well dispersed and toner particles having a predetermined particle diameter cannot be obtained. On the other hand, when the usage-amount of an aqueous medium exceeds 2000 weight part, it is not economical.
Moreover, a dispersing agent can also be used as needed as mentioned above. The use of a dispersant is preferable in that the particle size distribution becomes sharp and the dispersion is stable.

  In the step of synthesizing the urea-modified polyester [modified polyester (i)] from the polyester prepolymer (A) and the amines (B), the toner material liquid (oil phase) containing (A) is dispersed in an aqueous medium in advance. The amine (B) may be added and reacted in advance, or the toner material liquid (oil phase) containing (A) may be dispersed in an aqueous medium and then the amine (B) may be added and reacted. (Reaction from the particle interface). In this case, urea-modified polyester is preferentially generated on the surface of the base particle to be formed, and a concentration gradient can be provided inside the particle.

  A surfactant may be used as a dispersant for emulsifying and dispersing a stock solution (oil phase) of a toner material in which the toner material (toner composition) is dispersed in a liquid (aqueous medium: aqueous phase) containing water. it can. As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine. It is.

  Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkylcarboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [omega-fluoroalkyl (C6-C11). ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [omega-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkyl carboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctane sulfonic acid diethanolamide, N-propyl-N- ( 2-hydroxy Til) perfluorooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphoric acid Examples include esters. Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (Daikin Kogyo Co., Ltd.), MegaFuck F-110, F-120, F-113, F-191, F-812, F-833 (Dainippon Ink Co., Ltd.), Xtop EF-102 , 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

  Examples of cationic surfactants include aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, aliphatic quaternary ammonium salts such as perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, benza Luconium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass), Florard FC-135 (Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Megafac F-150, F-824 (manufactured by Dainippon Ink, Inc.), Xtop EF-132 (manufactured by Tochem Products), and Footgent F-300 (manufactured by Neos).

  Further, tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, hydroxyapatite and the like can be used as an inorganic compound dispersant which is hardly soluble in water. Further, the dispersed droplets may be stabilized by a polymer protective colloid. Examples of the polymeric protective colloid include acrylic acids, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride, or hydroxyl groups. Containing (meth) acrylic monomer, for example, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, methacryl Γ-hydroxypropyl acid, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glyce Phosphorus monomethacrylate, N-methylol acrylamide, N-methylol methacrylamide, etc., or vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or vinyl alcohol and carboxyl group Esters of compounds containing, for example, vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine , Homopolymers or copolymers such as those having a nitrogen atom such as vinylpyrrolidone, vinylimidazole, ethyleneimine, or a heterocyclic ring thereof, Or polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxy Polyoxyethylenes such as ethylene stearyl phenyl ester and polyoxyethylene nonyl phenyl ester, and celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  In addition, when an acid such as calcium phosphate salt or an alkali-soluble substance is used as the dispersion stabilizer, the calcium phosphate salt is removed from the fine particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. To do. It can also be removed by operations such as enzymatic degradation. When a dispersant is used, the dispersant can remain on the surface of the toner particles. However, it is preferable from the charged surface of the toner that the dispersant is washed and removed after the elongation and / or crosslinking reaction.

  Further, a solvent in which the modified polyester (i) or the prepolymer (A) is soluble is used in order to lower the viscosity of the toner material stock solution (oil phase) in which the toner material (toner composition) is dissolved or dispersed. You can also Use of such a solvent is preferable in that the particle size distribution becomes sharp. The boiling point of the solvent to be used is preferably less than 100 [° C.] and has volatility from the viewpoint of easy removal of the solvent. Examples of such solvents include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, acetic acid. Ethyl, methyl ethyl ketone, methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferable. The usage-amount of the solvent with respect to 100 weight part of polyester prepolymers (A) is 0-300 weight part normally, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part. When a solvent is used, it is removed by heating under normal pressure or reduced pressure after elongation and / or crosslinking reaction.

  The crosslinking reaction time for elongation, crosslinking, or stretch crosslinking is selected depending on the reactivity of the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 [° C.], preferably 40 to 98 [° C.]. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

  In order to remove the organic solvent from the emulsified dispersion obtained by emulsifying or dispersing the stock solution (oil phase) of the toner material in the aqueous medium (aqueous phase), the temperature of the whole system is gradually increased, The method of completely evaporating and removing the organic solvent can be employed. Alternatively, the emulsified dispersion can be sprayed into a dry atmosphere to completely remove the water-insoluble organic solvent in the droplets to form fine particles that form the base particles, and the aqueous dispersant can also be removed by evaporation. It is. As a dry atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, in particular, various air currents heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used is generally used. Sufficient quality can be obtained with a short treatment such as spray dryer, belt dryer or rotary kiln.

  When the particle size distribution at the time of emulsification dispersion becomes wide, the particle size distribution can be adjusted by classifying the particle size distribution to a desired particle size distribution even if washing and drying are performed while maintaining the particle size distribution. Examples of the classification method include a method of removing the fine particle portion of the unnecessary size by cyclone, decanter, centrifugation, or the like in the liquid. Classification may be performed after drying to form a powder, but it is preferable in terms of efficiency to be performed in a liquid. The unnecessary-sized fine particles or coarse particles removed by classification can be returned to the kneading process and used to form particles. At that time, fine particles or coarse particles may be wet. The dispersant is preferably removed from the dispersion as much as possible, and is preferably performed simultaneously with the classification operation described above.

  If necessary, the dried powder (base particles) can be mixed with different types of particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles, or mechanical impact can be applied to the mixed powder. A toner having base particles can be obtained by applying force. By applying a mechanical impact force, it is possible to prevent dissociation of different particles from the surface of the toner (composite particles) having the obtained base particles.

  Specific means for applying a mechanical impact force include a method of applying an impact force to the mixture by a blade rotating at high speed, a mixture is injected into a high-speed air stream, and the mixture is accelerated to bring the particles or composite particles into a suitable collision plate. There is a method of making it collide. As equipment, Ong mill (manufactured by Hosokawa Micron Co., Ltd.), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) is modified to reduce the grinding air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron system (Made by Kawasaki Heavy Industries, Ltd.), automatic mortar and the like.

(Developer)
The developer according to the present invention includes the toner, and preferably includes a carrier and the toner.
The carrier to toner content ratio is preferably 1 to 10 parts by weight of toner with respect to 100 parts by weight of carrier. As the magnetic carrier, conventionally known ones such as iron powder, ferrite powder, magnetite powder, magnetic resin carrier having a particle diameter of about 20 to 200 [μm] can be used.

  Examples of the coating material for the magnetic carrier include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Polyvinyl and polyvinylidene resins such as acrylic resins, polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins and styrene acrylic copolymer resins, Halogenated olefin resins such as polyvinyl chloride, polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytrifluoroethylene resins, poly Hexafluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, tetrafluoroethylene and vinyl fluoride It can be used den fluoro such as terpolymers of non-fluoride monomers including, and silicone resins. Moreover, you may contain electrically conductive powder etc. in coating resin as needed. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide or the like can be used. These conductive powders preferably have an average particle diameter of 1 [μm] or less. When the average particle diameter is larger than 1 [μm], it becomes difficult to control electric resistance. In the present invention, the toner can also be used as a one-component developer (magnetic toner or non-magnetic toner) that does not use a carrier.

[Image forming apparatus, process cartridge, image forming method]
An image forming apparatus according to the present invention includes a color image forming unit that forms a color image on a recording medium using one or more colored toners, and transparent toner on the color image formed by the color image forming unit. And a transparent image forming unit that forms a transparent image using the color image and the fixing unit that fixes the color image and the transparent image carried on the recording medium to the recording medium.
The process cartridge according to the present invention is used in the above-described image forming apparatus and is detachable from the main body of the image forming apparatus, and a color image is recorded on a recording medium using at least an image carrier and one or more colored toners. And a color image forming unit for forming a transparent image on the color image formed by the color image forming unit using a transparent toner. Further, a charging unit, a cleaning unit, and other units may be provided integrally.

FIG. 3 shows an outline of an image forming apparatus to which the present invention is applied.
The image forming apparatus 100 is a color laser printer, but may be other types of image forming apparatuses such as other types of printers, facsimile machines, copiers, and multifunction machines of copiers and printers. The image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside. The image forming apparatus 100 can form an image using plain paper generally used for copying, OHP sheets, thick paper such as cards and postcards, and envelopes as sheet-like recording media. .

The image forming apparatus 100 originally substitutes the transparent toner for the BK toner station. In the drawing, the part described as BK is described in place of W (colorless and transparent) in the explanatory text. In this embodiment, the intermediate transfer belt is rotated twice so that a transparent toner layer (transparent image) is provided on the colored toner in a color image (colored toner layer) on paper (recording medium). A method is used in which the transparent toner is developed on the circumference and the colored toner is developed on the second circumference.
The image forming apparatus 100 is a photoreceptor that is a latent image carrier as an image carrier that can form an image as an image corresponding to each of the colors separated into yellow, magenta, cyan, and colorless and transparent (W). A tandem structure in which the drums 20Y, 20M, 20C, and 20W are arranged in parallel, in other words, a tandem system is adopted.

  The photosensitive drums 20Y, 20M, 20C, and 20W are rotatably supported by a frame (not shown) of the main body 99 of the image forming apparatus 100, and are the moving directions of the transfer belt 11 that is an intermediate transfer member, and are clockwise in FIG. Are arranged in this order from the upstream side in the A1 direction. “Y”, “M”, “C”, and “W” attached to the numbers of the respective symbols indicate yellow, magenta, cyan, and colorless and transparent members.

  The photosensitive drums 20Y, 20M, 20C, and 20W are image forming units 60Y and 60M for forming yellow (Y), magenta (M), cyan (C), and colorless and transparent (W) images, respectively. , 60C, 60W.

  The photoconductive drums 20Y, 20M, 20C, and 20W are located on the outer peripheral surface side, that is, the image forming surface side of the transfer belt 11 that is configured as an endless belt disposed almost at the center inside the main body 99.

  The transfer belt 11 is movable in the direction of the arrow A1 while facing the photosensitive drums 20Y, 20M, 20C, and 20W. Visible images, that is, toner images formed on the photosensitive drums 20Y, 20M, 20C, and 20W are respectively superimposed and transferred onto the transfer belt 11 that moves in the direction of the arrow A1, and then collectively onto the transfer sheet S that is a recording medium. It is designed to be transcribed. Therefore, the image forming apparatus 100 is an intermediate transfer type image forming apparatus.

  The upper portion of the transfer belt 11 faces the photosensitive drums 20Y, 20M, 20C, and 20W, and the opposed portions transfer the toner images on the photosensitive drums 20Y, 20M, 20C, and 20W. A primary transfer portion 58 for transferring to the belt 11 is formed.

  In the superimposing transfer to the transfer belt 11, the toner images formed on the photosensitive drums 20Y, 20M, 20C, and 20W are transferred to the same position on the transfer belt 11 while the transfer belt 11 moves in the A1 direction. In such a manner, voltage is applied by primary transfer rollers 12Y, 12M, 12C, and 12W as primary transfer devices disposed at positions facing the respective photosensitive drums 20Y, 20M, 20C, and 20W with the transfer belt 11 interposed therebetween. The timing is shifted from the upstream side toward the downstream side in the A1 direction.

  The transfer belt 11 has a multilayer structure in which the base layer is made of a material with little elongation, the surface of the base layer is covered with a smooth material, and the coat layer is formed on the base layer. Examples of the material of the base layer include a fluororesin, a PVD sheet, and a polyimide resin. Examples of the material of the coat layer include a fluorine resin.

  The image forming apparatus 100 is disposed in the main body 99 so as to oppose the four image forming units 60Y, 60M, 60C, and 60W and below the photosensitive drums 20Y, 20M, 20C, and 20W. A transfer belt unit 10 as an intermediate transfer unit, which is an intermediate transfer device provided, a secondary transfer device 5 disposed opposite to the transfer belt 11 below the transfer belt 11 in FIG. 3, and an image forming unit 60Y. , 60M, 60C, 60W, and an optical scanning unit 8 as an exposure unit as an optical writing unit as an optical writing unit as a latent image forming unit.

  The image forming apparatus 100 also serves as a paper feed cassette capable of stacking a large number of transfer sheets S conveyed toward the secondary transfer unit 57 between the transfer belt 11 and the secondary transfer apparatus 5 in the main body 99. The sheet transfer device 61 and the recording sheet S conveyed from the sheet supply device 61 are transferred to the secondary transfer unit at a predetermined timing in accordance with the toner image formation timing by the image forming units 60Y, 60M, 60C, and 60W. A registration roller pair 4 that is fed out toward the registration roller 57 and a sensor (not shown) that detects that the leading edge of the transfer sheet S has reached the registration roller pair 4 are provided.

  The image forming apparatus 100 also includes a fixing device (fixing means) 6 as a fixing unit of a belt fixing system for fixing the toner image on the transfer sheet S on which the toner image is transferred, and a secondary transfer. A belt conveying device 87 that conveys the recording paper S that has passed through the section 57 to the fixing device 6; a paper discharge roller 7 as a paper discharge roller pair that is a discharge roller that discharges the fixed transfer paper S to the outside of the main body 99; A paper discharge tray 17 serving as a paper discharge unit for stacking the transfer paper S discharged from the main body 99 by the main discharge roller 7 and an upper portion of the main body 99 are provided for each of yellow, cyan, magenta, and colorless and transparent colors. It has toner bottles 9Y, 9M, 9C, 9W filled with image forming toner, that is, toner.

  The image forming apparatus 100 also includes an optical scanning device support frame 97 to which the optical scanning device 8 is fastened and fixed, a plate-shaped side plate 98 to which the optical scanning device support frame 97 is positioned and fixed, and the photosensitive drums 20Y, 20M, 20C, A control unit including a drive unit (not shown) provided to correspond to each of the 20 Ws and rotating the photosensitive drums 20Y, 20M, 20C, and 20W; a CPU (not shown) that controls the overall operation of the image forming apparatus 100; 64.

  In addition to the transfer belt 11, the transfer belt unit 10 includes primary transfer rollers 12Y, 12M, 12C, and 12W as primary transfer bias rollers, and a drive roller 72 that is a drive member around which the transfer belt 11 is wound. A counter roller 74 as a tension roller, tension rollers 33, 66, 67, 75 as support rollers for tensioning the transfer belt 11 together with the driving roller 72 and the cleaning counter roller 74, and the transfer belt 11. And a cleaning device 13 as a belt cleaning device which is an intermediate transfer member cleaning device for cleaning the surface of the transfer belt 11.

  The transfer belt unit 10 also includes a drive system (not shown) that rotationally drives the drive roller 72, and a power source and bias control as bias application means (not shown) that applies a primary transfer bias to the primary transfer rollers 12Y, 12M, 12C, and 12W. Means.

  The cleaning facing roller 74 and the stretching rollers 33, 66, 67, and 75 are driven rollers that rotate with the transfer belt 11 that is rotationally driven by the driving roller 72. The primary transfer rollers 12Y, 12M, 12C, and 12W press the transfer belt 11 from the back surface thereof toward the photosensitive drums 20Y, 20M, 20C, and 20W to form primary transfer nips, respectively. The primary transfer nip is formed in a portion of the transfer belt 11 that extends between the stretching rollers 75. The tension roller 75 has a function of stabilizing the primary transfer nip.

  In each primary transfer nip, a primary transfer electric field is formed between the photosensitive drums 20Y, 20M, 20C, and 20W and the primary transfer rollers 12Y, 12M, 12C, and 12W due to the influence of the primary transfer bias. . The toner images of the respective colors formed on the photosensitive drums 20Y, 20M, 20C, and 20W are primarily transferred onto the transfer belt 11 due to the influence of the primary transfer electric field and nip pressure.

The tension roller 33 is brought into contact with the secondary transfer device 5 via the transfer belt 11 to form a secondary transfer portion 57.
The tension roller 66 has a function as a tension roller as a pressure member that gives the transfer belt 11 a predetermined tension suitable for transfer.

  The cleaning device 13 includes a cleaning blade 76 disposed so as to contact the transfer belt 11 at a position facing the cleaning counter roller 74, and a transfer belt facing the cleaning counter roller 74 upstream of the cleaning blade 76 in the A1 direction. 11, a brush roller 68 disposed opposite to the main body 11, and a case 77 in which the cleaning blade 76 and the brush roller 68 are accommodated.

  The cleaning device 13 cleans the transfer belt 11 by scraping and removing foreign matters such as residual toner on the transfer belt 11 with the brush roller 68 and the cleaning blade 76.

  The transfer belt 11 rotates at a linear speed of 450 mm / sec by the operation of the drive system. However, this linear velocity is adjusted to match the system speed of the image forming apparatus 100. The system linear velocity is set at 400 mm / sec or more and 1700 mm / sec or less. As described above, the image forming apparatus 100 is a high-speed machine, and among these high-speed machines, the system linear speed is an ultra-high-speed machine having an ultra-high system speed. As a result, the image forming apparatus 100 can form an image of 70 sheets or more per minute when the transfer sheet S transported vertically in the transport direction is A4 size.

  The sheet feeding device 61 accommodates a plurality of transfer paper S in a state of a stack of transfer paper, and is arranged in a multi-stage below the optical scanning device 8 below the main body 99. The paper bank 31 is formed at the bottom of the main body 99 by the multistage sheet feeding device 61.

  The sheet feeding device 61 has a feeding roller 3 as a sheet feeding roller pressed against the upper surface of the uppermost transfer sheet S, and the feeding roller 3 is driven to rotate counterclockwise at a predetermined timing. As a result, the uppermost transfer sheet S is fed toward the registration roller pair 4.

  The transfer sheet S delivered from the sheet feeding device 61 reaches the registration roller pair 4 through the sheet feeding path 32 and is sandwiched between the rollers of the registration roller pair 4. Thereafter, the registration roller pair 4 feeds the transfer sheet S toward the secondary transfer unit 57.

  The secondary transfer device 5 is disposed to face the stretching roller 33. The secondary transfer device 5 is configured to form a nip portion that is the secondary transfer portion 57 by bringing the secondary transfer roller 69 into contact with the transfer belt 11, and the secondary transfer portion that is the nip portion. The toner image on the transfer belt 11 is transferred to the transfer paper S through the transfer paper S 57.

  The fixing device 6 includes a heater lamp 81 which is a heating unit as a heat source, a heating roller 91 having the heater lamp 81 therein, an endless fixing belt 92 wound around the heating roller 91, and the fixing belt together with the heating roller 91. A pressure roller that presses the fixing belt 92 between the fixing roller 93 and the auxiliary roller 95, which is a tension roller, and the fixing roller 93 provided at a position facing the fixing roller 93 via the fixing belt 92. It has a pressure roller 94 as a member, and a heater lamp 82 as a heat source disposed inside the pressure roller 94 as a heat source.

  The fixing device 6 also includes a heat pipe 83 integral with the heating roller 91, an oil application mechanism 84 that applies oil as a release agent to the fixing belt 92 wound around the heating roller 91, and a heating roller 91. A thermopile 85 disposed opposite to the fixing belt 92 at the wound position, a temperature detecting means 86 connected to the thermopile 85 for detecting the surface temperature of the fixing belt 92, and a fixing roller 93 are driven to rotate. And a driving means (not shown) for rotating the fixing belt 92, the heating roller 91, the auxiliary roller 95, and the pressure roller 94.

The heating roller 91 is heated by a heater lamp 81 and is a roller for heating the fixing belt 92 from the inside.
The auxiliary roller 95 is disposed on the outer peripheral surface of the fixing belt 92 so as to come into contact with the fixing belt 92 in an offset state, and stretches the fixing belt 92.

As long as the pressure member is a rotating body, it may be in the form of a belt instead of a roller like the pressure roller 94.
The fixing roller 93 and the fixing belt 92 are each referred to as a fixing member singly or collectively.

  The fixing belt 92 has meandering detent ribs (not shown) at both ends to prevent meandering during rotation. The fixing belt 92 is rotated at a linear speed of 450 mm / sec by being driven to rotate through a fixing roller 93 by a driving unit. However, this linear velocity is appropriately adjusted so as to match the system speed of the image forming apparatus 100.

  In the fixing device 6 having such a configuration, the transfer sheet S carrying the toner image is passed through a fixing unit which is a pressure contact portion between the fixing belt 92 and the pressure roller 94, so that the toner image is supported by the action of heat and pressure. The toner image is permanently fixed on the surface of the sheet.

At that time, the driving of the heater lamp 81 is controlled based on the temperature detected by the temperature detecting means 86. Since the thermopile 85 is disposed at a position facing the heating roller 91 with the fixing belt 92 interposed therebetween, the temperature detecting means 86 is substantially disposed at this position, and the surface temperature of the fixing belt 92 is disposed at this position. Is supposed to be detected. When the temperature detection means 86 detects the temperature at this position, the surface temperature of the fixing belt 92 is detected well. The temperature detecting means can be disposed at other positions as long as it is disposed at least at this position.
The remainder of the fixing device 6 will be described later.

  The optical scanning device 8 deflects and scans a laser beam, which is a light beam, in accordance with image information input from the outside of the image forming apparatus 100 and irradiates the photosensitive drums 20Y, 20M, 20C, and 20W simultaneously. When the image forming apparatus 100 is a copying machine, the optical scanning device 8 triggers pressing of a copy switch or the like when a document set on a contact glass in a document reading device provided in the copying machine is used. The photosensitive drums 20Y, 20M, 20C, and 20W are irradiated with laser light according to the image information that is optically read and generated thereby, and an electrostatic latent image is formed by exposure. The exposure means is not limited to the method of the optical scanning device 8, but uses an LED array in which LEDs are arranged along the main scanning direction perpendicular to the paper surface of FIG. 3, which is the longitudinal direction of the photosensitive drums 20Y, 20M, 20C, and 20W. It may be.

  The yellow, cyan, magenta, and colorless and transparent toners in the toner bottles 9Y, 9M, 9C, and 9W are polymerized toners. The image forming units 60Y and 60M are supplied by a predetermined replenishment amount through a conveyance path (not shown). , 60C, 60W, the developing devices 80Y, 80M, 80C, 80W are replenished.

  Regarding the image forming units 60W (transparent image forming means), 60Y, 60M, and 60C (hereinafter referred to as color image forming means), one of them is representative of the configuration of the image forming unit 60Y including the photosensitive drum 20Y. explain. Since the configurations of the other image forming units are substantially the same, in the following description, for the sake of convenience, reference numerals corresponding to the reference numerals assigned to the configuration of the image forming unit 60Y are used for the configurations of the other image forming units. In addition, detailed descriptions will be omitted as appropriate, and those with W, Y, M, and C at the end of the reference numerals are used for forming colorless, transparent, yellow, magenta, and cyan images, respectively. It shall be shown that it is a configuration.

  The image forming unit 60Y has a primary transfer roller 12Y, a cleaning device 71Y as a cleaning unit, and a neutralizing unit as a neutralizing unit around the photosensitive drum 20Y along a rotation direction B1 that is counterclockwise in FIG. It has a static elimination device (not shown), a charging device 79Y as a charging means for performing AC charging, and a developing device 80Y as a developing means for performing development with a two-component developer that is an image forming developer.

The photosensitive drum 20Y is driven by a driving device and rotates at a predetermined peripheral speed in the B1 direction.
The cleaning device 71Y is provided with an elastic rubber blade (not shown) that is in contact with the photosensitive drum 20Y in the counter direction and remains on the photosensitive drum 20Y after the primary transfer by the primary transfer roller 12Y. The toner remaining on the photosensitive drum 20Y is scraped off and removed by the cleaning blade to clean the photosensitive drum 20Y.

  The static eliminator includes a static eliminator that removes the charge remaining on the surface of the photosensitive drum 20Y cleaned by the cleaning device 71Y and initializes the surface potential of the photosensitive drum 20Y.

  The charging device 79Y includes a charging roller (not shown) that is in contact with the photosensitive drum 20Y, and uniformly charges the surface of the photosensitive drum 20Y that has been neutralized by the neutralizing device.

  Since the cleaning device 71Y includes the elastic rubber blade and the charging device 79Y includes the charging roller, the photosensitive drum 20Y is cleaned and charged satisfactorily.

The developing device 80Y has a developing roller (not shown) opposed to the photosensitive drum 20Y, and the optical scanning device 8 in the developing region for supplying the toner contained in the developer carried on the developing roller to the photosensitive drum 20Y. The electrostatic latent image is developed and visualized by attaching the toner only to the image forming portion of the non-image portion and the image forming portion constituting the electrostatic latent image formed by the toner image on the surface of the photosensitive drum 20Y. A toner image is formed.
Details of the toner used in the developing device 80Y, in other words, the toner used in the image forming apparatus 100 will be described later.

  The photosensitive drum 20Y, the cleaning device 71Y, the charge eliminating device, the charging device 79Y, and the developing device 80Y constitute a process cartridge 88Y that is detachable from the main body 99. Making a process cartridge in this way is very preferable because it can be handled as a replacement part, so that the maintainability is remarkably improved. The two-component developer includes the process cartridge that includes the photosensitive drum 20Y and at least the developing device 80Y among the cleaning device 71Y, the charge eliminating device, the charging device 79Y, and the developing device 80Y. This is preferable because the carrier is replaced when the developing device 80Y is replaced.

  In the image forming apparatus 100 having such a configuration, when a signal indicating that a color image is to be formed is input, the driving roller 72 is driven, and the transfer belt 11, the cleaning facing roller 74, and the stretching rollers 33, 66, 67. , 75 are driven to rotate and the photosensitive drums 20Y, 20M, 20C, 20W are rotationally driven in the B1 direction.

  The photosensitive drums 20Y, 20M, 20C, and 20W are uniformly charged on the surface by the charging devices 79Y, 79M, 79C, and 79W as they rotate in the B1 direction, and exposure scanning of the laser beam from the optical scanning device 8 is performed. The electrostatic latent image corresponding to each color of yellow, magenta, cyan, and colorless and transparent is formed by this, and the toner of each color of yellow, magenta, cyan, and colorless and transparent is formed on this electrostatic latent image by the developing devices 80Y, 80M, 80C, and 80W. Is developed.

  The yellow, magenta, cyan, and colorless and transparent toner images obtained by development are sequentially placed at the same position on the transfer belt 11 rotating in the A1 direction by the primary transfer rollers 12W, 12Y, 12M, and 12C. Multiple transfer is performed, and a composite color image is formed on the transfer belt 11.

  On the other hand, any one of the sheet feeding devices 61 provided in the paper bank 31 in response to an input of a signal indicating that a color image should be formed, or when the image forming apparatus 100 is a copying machine, a press of a copy switch or the like. Is selected, and the feeding roller 3 provided in the selected sheet feeding device 61 rotates to feed out the transfer sheet S, separate it one by one and feed it to the paper feed path 32, and feeds it to the paper feed path 32. The transferred sheet S is further transported by a transport roller (not shown) and stops in a state where it is abutted against the registration roller pair 4.

  The registration roller pair 4 rotates in accordance with the timing at which the composite color image superimposed on the transfer belt 11 moves to the secondary transfer unit 57 as the transfer belt 11 rotates in the A1 direction. The combined color image is in close contact with the transfer sheet S sent to the secondary transfer unit 57, and is secondarily transferred and recorded on the transfer sheet S by the action of a bias formed by the nip pressure and the power source.

  The transfer paper S is sent to the fixing device 6 by the belt conveying device 87, and when the fixing paper 6 passes through the fixing portion between the fixing belt 92 and the pressure roller 94, the toner that is carried by the action of heat and pressure. The image or composite color image is fixed. This fixing is performed well as will be described later.

  The transfer sheet S on which the composite color image has been fixed, which has passed through the fixing device 6, is discharged out of the main body 99 through the discharge roller 7 and stacked on the discharge tray 17 at the top of the main body 99.

  In the photosensitive drums 20Y, 20M, 20C, and 20W, the transfer residual toner remaining after the transfer is removed by the cleaning devices 71Y, 71M, 71C, and 71W, discharged by the discharging device, and then discharged by the charging devices 79Y, 79M, 79C, and 79W. Used for charging.

  The surface of the transfer belt 11 that has passed the secondary transfer portion 57 after the secondary transfer is cleaned by a cleaning blade 76 provided in the cleaning device 13 to prepare for the next transfer.

  The image forming operation in the image forming apparatus 100 is performed as described above. In the image forming apparatus 100, in the fixing device 6, as shown in FIG. 4, the fixing belt 92 preferably includes at least a base material layer 92a and a rubber layer 92b, and further includes a release layer 92c. The thickness L1 of the rubber layer 92b is preferably 400 μm or more and 1200 μm or less, and the thickness L2 of the release layer 92c is preferably 1.5 μm or more and 20 μm or less. The fixing unit preferably includes an endless fixing belt, but may have other forms such as a roller. In the image forming operation, the toner has the composition and characteristics described above.

As the material of the base material layer 92a, a material having excellent heat resistance is selected from a resin such as polyimide resin and a metal such as nickel.
The material of the rubber layer 92b is a material different from that of the base material layer 92a and functions as a heat storage layer selected from materials having a large heat capacity and a high heat transport amount. Specifically, a rubber-based material is suitable for the material of the rubber layer 92b, and silicone rubber is particularly preferable.
The release layer 92c forms the uppermost surface of the fixing belt 92 and is used as a fixing surface in contact with the toner. Therefore, the release property is particularly regarded as important. Therefore, the release layer 92c is made of a fluorine-based material that is very useful for ensuring release properties. In this embodiment, the release layer 92c is made of a fluororesin, specifically PFA, and is a fluororesin layer.

  The fixing device 6 includes an oil application mechanism 84 that applies oil as a release agent to the surface of the fixing belt 92 in order to improve releasability. In this regard, if the release layer 92c, which is the uppermost layer, is formed of a material different from that of the fluororesin, the familiarity of the oil is poor and the effect of the oil is not sufficiently exhibited, but the release layer 92c is formed of PFA which is a fluororesin. Therefore, the compatibility with the oil is good and the releasability is sufficiently exhibited.

The layer thicknesses L1 and L2 will be described.
Since the rubber layer 92b places importance on the heat storage function, the layer thickness L1 is preferably in the range of 400 μm or more and 1200 μm or less. This is because if the layer thickness L1 is less than 400 μm, the heat storage effect does not appear sufficiently, the amount of heat to the toner tends to be insufficient, and gloss unevenness tends to occur. Conversely, if the layer thickness L1 is greater than 1200 μm, the thermal inertia increases. This is because the rise characteristic is deteriorated.
In contrast, since the release layer 92c is used with emphasis on releasability, the layer thickness L2 can sufficiently function even if the layer thickness L2 is smaller than the layer thickness L1, and ranges from 1.5 μm to 20 μm. It is preferable that This is because when the layer thickness L2 is smaller than 1.5 μm, the durability is insufficient, and conversely, when it is larger than 20 μm, a problem occurs in the amount of heat transport and gloss unevenness is likely to occur.

  In the example shown in FIG. 4, the rubber layer 92b is overlaid on the base material layer 92a and the release layer 92c is overlaid on the rubber layer 92b. However, the base material layer 92a, the rubber layer 92b, and the release material are overlaid. If the functions of these layers are sufficiently exhibited between the layers 92c, it is not excluded to intervene other layers. Further, the thicknesses and thickness ratios of the base material layer 92a, the rubber layer 92b, and the release layer 92c shown in FIG.

  The fixing device 6 described above contributes to the provision of an image forming apparatus that does not increase the size and complexity of the image forming apparatus 100 and the image forming apparatus 100, and is inexpensive and outputs stable fixing image quality. .

Next, an experiment conducted by the inventor will be described.
In order to obtain toners having various properties, the present inventor first prepared toner materials as follows.

<Synthesis of organic fine particle emulsion>
In a reaction vessel equipped with a stirrer and a thermometer, 700 parts by weight of water, 12 parts by weight of sodium salt of ethylene oxide methacrylate adduct sulfate (Eleminol RS-30: manufactured by Sanyo Chemical Industries), 140 parts by weight of styrene, methacrylic acid 140 parts by weight and 1.5 parts by weight of ammonium persulfate were charged. Then, the white emulsion obtained by stirring for 20 minutes at 450 rpm was heated to an internal temperature of 78 [° C.] and reacted for 6 hours. To the emulsion, 35 parts by weight of 1% aqueous ammonium persulfate solution was added and aged at 82 [° C.] for 8 hours, followed by vinyl resin (styrene salt of styrene-methacrylic acid-methacrylic acid ethylene oxide adduct sulfate salt). An aqueous dispersion [fine particle dispersion 1] was obtained. When the volume average particle diameter of the [fine particle dispersion 1] was measured by LA-920 (details will be described later), it was 0.30 [μm]. A portion of [Fine Particle Dispersion 1] was dried to isolate the resin component. The Tg of the resin content was 151 [° C.].

<Preparation of aqueous phase>
Mixing and stirring 1000 parts by weight of water, 95 parts by weight of [fine particle dispersion 1], 50 parts by weight of 50% aqueous solution of dodecyl diphenyl ether sodium disulfonate (Eleminol MON-7: manufactured by Sanyo Chemical Industries), and 95 parts by weight of ethyl acetate As a result, a milky white liquid was obtained. This was designated as [Aqueous Phase 1].

<Synthesis of low molecular weight polyester <polyester having a hydroxyl group>
In a reaction vessel equipped with a condenser, a stirrer and a nitrogen introduction tube, 240 parts by weight of bisphenol A ethylene oxide 2-mole adduct, 540 parts by weight of bisphenol A propylene oxide 3-mole adduct, 220 parts by weight of terephthalic acid, 55 adipic acid 55 Part by weight and 4 parts by weight of dibutyltin oxide were added. Then, after reacting at 250 [° C.] for 8 hours under normal pressure, the reaction was carried out at 5 hours under reduced pressure of 10 to 20 [mmHg]. Thereafter, 50 parts of trimellitic anhydride was put in a reaction vessel and reacted at 190 [° C.] and normal pressure for 5 hours to obtain [Low molecular weight polyester 1]. This [low molecular polyester 1] had a number average molecular weight of 2600, a weight average molecular weight of 7000, a Tg of 44 [° C.], and an acid value of 23 [mg KOH / g].

<Synthesis of polyester prepolymer <polyester prepolymer having an isocyanate group>
In a reaction vessel equipped with a condenser, a stirrer and a nitrogen introduction pipe, 680 parts by weight of bisphenol A ethylene oxide 2-mole adduct, 82 parts by weight of bisphenol A propylene oxide 2-mole adduct, 280 parts by weight of terephthalic acid, 23 parts by weight of merit acid and 2 parts by weight of dibutyltin oxide were added. And it was made to react at normal pressure and 250 [degreeC] for 8 hours, Then, it was made to react under the reduced pressure environment of 10-20 [mmHg] for 5 hours, and [intermediate polyester 1] was obtained. This [intermediate polyester 1] had a number average molecular weight of 2300, a weight average molecular weight of 10,000, Tg of 59 [° C.], an acid value of 0.5 [mg KOH / g], and a hydroxyl value of 52 [mg KOH / g].

  Next, 420 parts by weight of [Intermediate Polyester 1], 85 parts by weight of isophorone diisocyanate, and 500 parts of ethyl acetate were placed in a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube. And it was made to react at 120 [degreeC] for 6 hours, and [Prepolymer 1] was obtained. This [Prepolymer 1] had a free isocyanate weight% of 1.60 [%].

<Synthesis of crystalline polyester 1>
In a 5-liter four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer and thermocouple, 27 moles of 1,4-butanediol, 23 moles of fumaric acid, 1.70 moles of trimellitic anhydride, and hydroquinone 6.5 [g] was added. Then, after reacting at 170 [° C.] for 10 hours, the temperature was raised to 220 [° C.] and reacted for 3 hours, and further reacted at 8.3 KPa for 3 hours to obtain [Crystalline Polyester 1]. This [Crystalline Polyester 1] had a melting point (DSC endothermic peak temperature) of 150 [° C.], Mn1000, and Mw5000.

<Synthesis of crystalline polyester 2>
In a 5-liter four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer and thermocouple, 27 moles of 1,4-butanediol, 23 moles of fumaric acid, 1.70 moles of trimellitic anhydride, and hydroquinone 6.5 [g] was added. Then, after reacting at 140 [° C.] for 3 hours, the temperature was raised to 190 [° C.] and reacted for 0.5 hours, and further reacted at 8.3 KPa for 0.5 hours [Crystalline Polyester 2]. Got. This [Crystalline Polyester 2] had a melting point (DSC endothermic peak temperature) of 50 [° C.], Mn600, and Mw2500.

<Synthesis of ketimine>
In a reaction vessel equipped with a stirrer and a thermometer, 180 parts by weight of isophoronediamine and 80 parts by weight of methyl ethyl ketone were charged and reacted at 50 ° C. for 6 hours to obtain [ketimine compound 1]. The amine value of this [ketimine compound 1] was 420 [mgKOH / g].

<Preparation of Oil Phase <WAX Dispersion 1 >>
In a container equipped with a stir bar and a thermometer, 420 parts by weight of [low molecular weight polyester 1], ester WAX (oxidation: 0.1 KOH mg / g melting point: 65 ° C.): 110 parts (melt viscosity at 120 ° C. is 1.1 mPa · Second), 22 parts by weight of CCA (salicylic acid metal complex E-84: Orient Chemical Industry) and 1000 parts by weight of ethyl acetate were charged. Then, the temperature was raised to 80 [° C.] with stirring, maintained at 80 [° C.] for 10 hours, and then cooled to 24 [° C.] in 1 hour. Next, 550 parts of ethyl acetate was charged into the container and mixed for 1 hour to obtain [Raw material solution 1]. Using a bead mill (Ultra Visco Mill, manufactured by Imex Co., Ltd.) in a separate container, this [raw material solution 1] was fed at a liquid feed speed of 1 [kg / hr], a disk peripheral speed of 6 [m / sec], and a diameter of 0. 80% by volume of 5 [mm] zirconia beads were filled. Then, it was dispersed under the condition of 3 passes. Thereafter, 1000 parts by weight of 63 [%] ethyl acetate solution of [low molecular weight polyester 1] was added, and one pass was performed with the bead mill under the above-mentioned conditions to obtain [WAX Dispersion 1]. The solid content concentration of this [WAX dispersion 1] (120 ° C., 60 minutes) was 54% by weight.

<Preparation of Oil Phase <WAX Dispersion 2 >>
[WAX Dispersion 1] except that 110 parts of ester WAX used in the preparation of [WAX Dispersion 1] was changed to 100 parts by weight of microcrystalline wax (acid value: 0.2 KOH mg / g, melting point: 150 ° C.). ] [WAX dispersion 2] was obtained in the same manner.

<Preparation of crystalline polyester dispersion>
[Crystalline polyester 1] 100 [g] and ethyl acetate 430 [g] were put into a metal 2 L container, heated and dissolved or dispersed at 80 [° C.], and then rapidly cooled in an ice-water bath. Glass beads (3 mmφ) 500 [ml] were added to this, and the mixture was stirred for 8 hours with a batch type sand mill (made by Campehapio Co., Ltd.) [Crystalline polyester dispersion 1] having a volume average particle size of 0.4 [μm]. Got.
Further, [Crystalline Polyester Dispersion 2] was obtained in the same manner as above except that [Crystalline Polyester 1] 115 [g] was changed to [Crystalline Polyester 2] 115 [g].
Next, a toner was manufactured using these materials.

[Example 1]
First, the following emulsification process was performed. That is, 620 parts by weight of [WAX Dispersion 1], 110 parts by weight of [Prepolymer 1], 8 parts by weight of [Crystalline Polyester Dispersion 1], and 4.5 parts by weight of [Ketimine Compound 1] were placed in a container. Then, after mixing for 2 minutes at 8,000 [rpm] with a TK homomixer (made by Tokushu Kika), 1400 parts by weight of [Aqueous Phase 1] is added to the container, and with a TK homomixer, a rotational speed of 14,000 [ rpm] for 30 minutes to obtain [Emulsion slurry 1].

  Subsequently, the following solvent removal process was performed. That is, [Emulsion slurry 1] is put into a container in which a stirrer and a thermometer are set, and after desolvation at 30 [° C.] for 15 hours, aging is performed at 45 [° C.] for 8 hours, and [dispersed slurry 1] Got.

Thereafter, 100 parts by weight of [Emulsified slurry 1] was filtered under reduced pressure. And
(1): 100 parts by weight of ion-exchanged water was added to the filter cake, and after mixing with a TK homomixer at 12,000 [rpm], the mixture was filtered.
(2): 100 parts by weight of a 10% aqueous sodium hydroxide solution was added to the filter cake of (1), mixed with a TK homomixer at a rotational speed of 12,000 [rpm], and then filtered under reduced pressure.
(3): 100 parts by weight of 10% hydrochloric acid was added to the filter cake of (2), mixed with a TK homomixer at 12,000 [rpm] for 10 minutes, and then filtered.
(4): Add 300 parts by weight of ion-exchanged water to the filter cake of (3), mix with a TK homomixer at 12,000 [rpm] for 10 minutes, and then filter twice. [Filter cake 1] was obtained. The [filter cake 1] was dried at 45 [° C.] for 48 hours in a circulating drier and then sieved with a mesh of 75 [μm] mesh to obtain [base particles 1].

  With respect to 100 parts by weight of the [base particle 1] thus obtained, 0.45 parts by weight of hydrophobic silica (average number particle diameter: 15 nm) and 0.30 weight of hydrophobic titanium oxide (average number particle diameter: 15 nm) part was mixed with a Henschel mixer to obtain a transparent toner having base particles. The volume average particle size of the transparent toner was 5.5 μm, and the toner particle size ratio was 1.25.

  As the colored toner, M toner, Y toner, and C toner of colored toner are used in the same manner as the transparent toner, except that 480 parts by weight of the following [master batch] is added at the time of preparing the WAX dispersion and adding ethyl acetate. Prototype.

<Synthesis of master batch>
1200 parts of water, 50 parts of pigment, 60 parts of a polyester resin (manufactured by Sanyo Kasei, RS801), 30 parts of water are further added and mixed with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), and the mixture is 150 using two rolls. After kneading at 30 ° C. for 30 minutes, it was rolled and cooled, and pulverized with a pulverizer to obtain a [master batch] for each colored toner.
In the case of M color toner, [Masterbatch M] was obtained using 50 parts of PR269 magenta pigment.
Similarly, in the case of Y color toner, [Masterbatch Y] was obtained using 50 parts of PY155 yellow pigment.
Similarly, in the case of the C color toner, [Masterbatch C] was obtained using 50 parts of PB15: 3 cyan pigment.

<Manufacture of carriers>
The following composition was dispersed with a homomixer for 10 minutes to obtain a silicone resin coating film forming solution. A sintered ferrite powder having a volume average particle size of 70 μm is used as the core material, and the temperature inside the coater is 40 ° C. by a Spira coater (Okada Seiko Co., Ltd.) so that the coating film forming solution has a film thickness of 0.15 μm on the core material surface. And then dried. The obtained carrier was fired in an electric furnace at 300 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an opening of 125 μm to prepare a carrier.

・ Silicone resin solution 132.2 parts [Solid content 23%, SR2410, Toray Dow Corning Silicone Co., Ltd.]
・ Aminosilane 0.66 parts [Solid content 100%, SH6020, manufactured by Toray Dow Corning Silicone Co., Ltd.]
Conductive particles 1 ... 31 parts [Substrate: alumina, surface treatment; lower layer = tin dioxide / upper layer = indium oxide containing tin dioxide, particle size: 0.35 μm, particle powder specific resistance: 3.5 Ω · cm ]
・ Toluene: 300 parts

<Preparation of developer>
8% by mass of the produced toner and 92% by mass of the carrier were mixed to prepare a two-component developer.

Next, using each toner and each developer obtained as described above, a print test was performed with a modified Ricoh Pro901 machine. Here, the following two brands of paper were used.
Brand 1: Ricoh PPC paper type 6000 <70W>, Basis weight: 80gsm
Brand 2: Rezac 66, Basis weight: 260gsm
Further, regarding the fixing belt in the image forming apparatus used in the print test, the thickness L1 of the rubber layer 92b was 400 μm, and the thickness L2 of the release layer 92c was 20 μm.
In the print test, test images with a printing rate of 6% were continuously output on 50,000 sheets of A3 size paper. Thereafter, evaluation image samples were output on A3 size paper, each of three R, G, and B colors as solid images, so that the transparent toner was in the uppermost layer of the image as sample images.
Using cyan, magenta, and yellow toners without using transparent toner, three R, G, and B colors were output as solid images, and evaluation image samples were output on A3 size paper.
The image surface gloss unevenness in each image was visually evaluated.
Further, the sensory evaluation of the color characteristic reproducibility of the image sample using the transparent toner was performed in comparison with the image sample using no transparent toner.
The case where the sensory evaluation result was very good was evaluated as ◎, the case where it was good as ○, the case where it was a little bad as Δ, and the case where it was bad as ×.

[Example 2]
The same procedure as in Example 1 was performed except that 8 parts by weight of [Crystalline Polyester Dispersion 1] used in the transparent toner of Example 1 was changed to 65 parts by weight.

Example 3
The same procedure as in Example 1 was performed except that 8 parts by weight of [Crystalline Polyester Dispersion 1] used in the transparent toner of Example 1 was changed to 38 parts by weight.

Example 4
The same operation as in Example 1 was performed except that 8 parts by weight of [Crystalline Polyester Dispersion 1] used in the transparent toner of Example 1 was changed to 15 parts by weight.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that 8 parts by weight of [Crystalline Polyester Dispersion 1] used in the transparent toner and the colored toner of Example 1 was changed to 5 parts by weight.

[Comparative Example 2]
8 parts by weight of [Crystalline Polyester Dispersion 1] used in the transparent toner of Example 1 was changed to 69 parts by weight, and 8 parts by weight of [Crystalline Polyester Dispersion 1] used in the colored toner was changed to 65 parts by weight. Except for the points described above, the same procedure as in Example 1 was performed.

[Comparative Example 3]
The same procedure as in Example 2 was performed except that 8 parts by weight of [Crystalline Polyester Dispersion 1] used in the colored toner of Example 2 was changed to 5 parts by weight.

[Comparative Example 4]
The same procedure as in Example 1 was performed except that 8 parts by weight of [Crystalline Polyester Dispersion 1] used in the colored toner of Example 1 was changed to 65 parts by weight.

Example 5
The same procedure as in Example 1 was performed except that 620 parts by weight of [WAX Dispersion 1] used in the transparent toner of Example 1 was changed to 590 parts by weight.

Example 6
The same procedure as in Example 1 was performed except that 620 parts by weight of [WAX Dispersion 1] used in the transparent toner of Example 1 was changed to 48 parts by weight.

Example 7
The same procedure as in Example 5 was performed, except that [Crystalline Polyester Dispersion 1] used in the transparent toner of Example 5 was changed to [Crystalline Polyester Dispersion 2].

Example 8
In Example 5, the same procedure as in Example 5 was performed, except that the thickness L1 of the rubber layer 92b of the fixing belt in the image forming apparatus was changed to 1200 μm and the thickness L2 of the release layer 92c was changed to 20 μm. .

Example 9
Example 5 is the same as Example 5 except that the thickness L1 of the rubber layer 92b of the fixing belt in the image forming apparatus is changed to 1200 μm and the thickness L2 of the release layer 92c is changed to 1.5 μm. Carried out.

  The melting point of the release agent is the temperature of the endothermic peak at which the endothermic amount becomes maximum in the differential heat curve obtained by differential scanning calorimetry (DSC). The endothermic peak temperature of the crystalline polyester resin was also measured by differential scanning calorimetry.

  Next, the present inventor analyzed the infrared absorption spectra of the crystalline polyester resin and the amorphous polyester resin as the binder resin for the transparent toner and the colored toner, respectively. Infrared spectroscopic analysis was performed by KBr method (total transmission method) using FT-IR (Fourier transform infrared spectroscopic measurement device) manufactured by Avatar370 / ThermoElectron. The infrared absorption spectrum is a graph in which the wave number (Wavenumbers) of irradiated infrared rays is taken on the horizontal axis of the two-dimensional locus and the absorbance (Absorbance) is taken on the vertical axis. Thereby, it is possible to know the structure of the substance to be analyzed.

FIG. 1 shows an example of an infrared absorption spectrum of a crystalline polyester resin.
As shown in the figure, the infrared absorption spectrum of the crystalline polyester resin has a falling peak point at which the absorbance becomes the lowest between wave numbers 1130 cm ^{−1 to} 1220 cm ⁻¹ (hereinafter referred to as “first falling peak point Fp1”). ) And a falling peak point where the absorbance is the second smallest (hereinafter referred to as “second falling peak point Fp2”), there is a maximum rising peak point Mp at which the absorbance is maximum.
A line segment connecting the first falling peak point Fp1 and the second falling peak point Fp2 is defined as a base line. Then, a vertical line is drawn from the maximum rising peak point Mp toward the horizontal axis, and the absolute value of the difference between the absorbance at the intersection with the baseline and the absorbance at the maximum rising peak point Mp is expressed as the height W of the maximum rising peak point Mp. And

FIG. 2 shows an example of an infrared absorption spectrum of an amorphous polyester resin.
As shown in the figure, the infrared absorption spectrum of the amorphous polyester resin has a maximum rising peak point Mp and a first falling peak point Fp1 at which the absorbance is minimum between wave numbers 780 cm ^{−1 to} 900 cm ⁻¹ . There is a second falling peak point Fp2 where the absorbance is the second smallest, and the maximum rising peak point Mp is located between the first falling peak point Fp1 and the second falling peak point Fp2. A line segment connecting the first falling peak point Fp1 and the second falling peak point Fp2 is defined as a base line. Then, a vertical line is drawn from the maximum rising peak point Mp toward the horizontal axis, and the absolute value of the difference between the absorbance at the intersection with the baseline and the absorbance at the maximum rising peak point Mp is expressed as the height of the maximum rising peak point Mp. Let R be. Moreover, let W / R be a peak ratio (W / R value).

  The results are shown in Table 1 below.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, the present invention is not a so-called tandem-type image forming apparatus such as the image forming apparatus 100 as long as the above-described configuration example can be applied, but sequentially applies each color on an image carrier such as a single photosensitive drum. The present invention can be similarly applied to a so-called one-drum type image forming apparatus that forms a toner image and sequentially superimposes each colored toner image to obtain a color image, and is not a color image forming apparatus but a monochrome image forming apparatus. It can also be applied to. Any type of image forming apparatus may employ a direct transfer system in which each color toner image is directly transferred to a recording medium such as transfer paper without using an intermediate transfer member.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

6 Fixing device 20Y, 20M, 20C, 20BK Image carrier 72Y, 72M, 72C, 72BK Cleaning means 79Y, 79M, 79C, 79BK Charging means 81 Heating means 86 Temperature detecting means 88Y, 88M, 88C, 88BK Process cartridge 91 Heating roller 92 Fixing belt 92a Base layer 92b Rubber layer 92c Release layer 93 Fixing roller 94 Pressure roller 99 Image forming apparatus body 100 Image forming apparatus L1 Rubber layer thickness L2 Release layer thickness S Recording medium

JP 60-90344 A JP-A 64-15755 Japanese Patent Laid-Open No. 2-82267 JP-A-3-229264 JP-A-3-41470 JP-A-11-305486 JP 62-63940 A JP 2002-214833 A JP 2005-338814 A

Claims (11)

Color image forming means for forming a color image on a recording medium using one or more colored toners;
Transparent image forming means for forming a transparent image using a transparent toner on the color image formed by the color image forming means;
Fixing means for fixing the color image and the transparent image carried on the recording medium to the recording medium,
Each of the transparent toner and the colored toner contains a release agent and a binder resin,
The binder resin includes a crystalline polyester resin and an amorphous resin,
The height of the maximum rising peak point in the infrared absorption spectrum of the crystalline polyester resin obtained by infrared spectroscopy (KBr total transmission method) using a Fourier transform infrared spectrometer is W, and the amorphous resin When the height of the maximum rising peak point in the infrared absorption spectrum is R, and the ratio W / R is X1 for the color toner and X2 for the transparent toner, both of the following formulas 1 and 2 are satisfied. An image forming apparatus.
0 ≦ X2-X1 ≦ 0.75 Formula 1
0.05 ≦ X2 ≦ 0.80 Expression 2   The image forming apparatus according to claim 1, wherein the fixing unit includes an endless fixing belt. The fixing unit has at least a base material layer and a rubber layer on the base material layer,
The image forming apparatus according to claim 1, wherein the rubber layer has a thickness of 400 μm or more and 1200 μm or less. The fixing unit has a release layer containing a fluororesin on the rubber layer,
The image forming apparatus according to claim 3, wherein the release layer has a thickness of 1.5 μm to 20 μm.   5. The image forming apparatus according to claim 1, wherein the releasing agent is a monoester wax obtained from a long-chain linear saturated fatty acid and a long-chain linear saturated alcohol. The transparent toner includes base particles containing the release agent and the binder resin, and an external additive.
The image forming apparatus according to any one of claims 1 to 5, wherein a release agent content of the base particles is 1 wt% or more and 20 wt% or less.   7. The transparent toner has an endothermic peak temperature of the crystalline polyester resin as measured by differential scanning calorimetry of 50 [° C.] or more and 150 [° C.] or less. Image forming apparatus. A toner set including one or more colored toners and a transparent toner,
Each of the transparent toner and the colored toner contains a release agent and a binder resin,
The binder resin includes a crystalline polyester resin and an amorphous resin,
The height of the maximum rising peak point in the infrared absorption spectrum of the crystalline polyester resin obtained by infrared spectroscopy (KBr total transmission method) using a Fourier transform infrared spectrometer is W, and the amorphous resin When the height of the maximum rising peak point in the infrared absorption spectrum is R, and the ratio W / R is X1 for the color toner and X2 for the transparent toner, both of the following formulas 1 and 2 are satisfied. Toner set.
0 ≦ X2-X1 ≦ 0.75 Formula 1
0.05 ≦ X2 ≦ 0.80 Expression 2 Developer which is a developer containing the transparent toner and the color toners used in the image forming apparatus according to any one of claims 1 to 7. A color image forming step of forming a color image on a recording medium using one or more colored toners;
A transparent image forming step of forming a transparent image using a transparent toner on the color image formed by the color image forming means;
A fixing step of fixing the color image and the transparent image carried on the recording medium to the recording medium,
Each of the transparent toner and the colored toner contains a release agent and a binder resin,
The binder resin includes a crystalline polyester resin and an amorphous resin,
The height of the maximum rising peak point in the infrared absorption spectrum of the crystalline polyester resin obtained by infrared spectroscopy (KBr total transmission method) using a Fourier transform infrared spectrometer is W, and the amorphous resin When the height of the maximum rising peak point in the infrared absorption spectrum is R, and the ratio W / R is X1 for the color toner and X2 for the transparent toner, both of the following formulas 1 and 2 are satisfied. An image forming method.
0 ≦ X2-X1 ≦ 0.75 Formula 1
0.05 ≦ X2 ≦ 0.80 Expression 2 Used in the image forming apparatus according to any one of claims 1 to 7, a process cartridge is detachably attached to the image forming apparatus main body,
At least an image carrier, a color image forming unit that forms a color image on a recording medium using one or more colored toners, and a transparent image using a transparent toner on the color image formed by the color image forming unit A process cartridge comprising: a transparent image forming unit that forms an image.