JP2018151468A - Image forming method and toner set for electrostatic latent image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means that can reduce environmental dependency of density unevenness of an image to be formed, while maintaining good low-temperature fixability.SOLUTION: The present invention relates to an image forming method using a black toner containing carbon black, a crystalline polyester resin having a constitutional unit derived from a straight chain aliphatic dicarboxylic acid, an amorphous resin, and a mold release agent, and a toner other than the black toner containing a crystalline polyester resin having a constitutional unit derived from a straight chain aliphatic dicarboxylic acid, an amorphous resin, and a mold release agent. When the number of carbons of the constitutional unit derived from the straight chain aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the black toner is A(B), and the number of carbons of the constitutional unit derived from the straight chain aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the toner other than the black toner is A(C), the following formula (1) is satisfied.SELECTED DRAWING: None

Description

  The present invention relates to an image forming method and an electrostatic latent image developing toner set.

  In recent years, from the viewpoint of speeding up and saving energy, a toner having excellent low-temperature fixability has been demanded in order to fix a toner image with less energy than before. In order to lower the toner fixing temperature, it is necessary to lower the melting temperature and the viscosity of the binder resin constituting the toner. In order to satisfy such a demand, development of a toner containing a crystalline resin having excellent melting characteristics has been underway.

  For example, Patent Document 1 proposes a toner set using a crystalline polyester resin as a binder resin for each color toner. Thus, when the crystalline polyester resin is introduced into the toner, the thermal melting of the toner can be lowered, and as a result, the low-temperature fixability is improved.

Japanese Patent Laid-Open No. 2008-90054

  However, when the full color image is formed by the toner set using the crystalline polyester resin as the binder resin of the toner of each color as in Patent Document 1, the present inventors depend on the surrounding environment to change the full color. It has been found that there is a problem of uneven density in the image. Therefore, there has been a demand for a technique capable of reducing the environmental dependency of density unevenness of an image to be formed as well as low-temperature fixability.

  Accordingly, an object of the present invention is to provide a means capable of reducing the environmental dependency of density unevenness of an image to be formed while maintaining good low-temperature fixability.

  The present inventors have conducted intensive studies in view of the above problems. As a result, a black toner containing carbon black, a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, an amorphous resin, and a release agent, and a linear aliphatic dicarboxylic acid An image forming method using a crystalline polyester resin having a structural unit derived from the above, a non-crystalline resin, and a toner other than the black toner, and including the black toner A linear aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the toner other than the black toner, wherein A (B) is the carbon number of the structural unit derived from the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin It has been found that the above problem is solved by an image forming method that satisfies the following formula (1), where A (C) is the carbon number of the structural unit derived from an acid. This has led to the completion of the present invention.

  In addition, the present inventors also disclosed a black toner containing carbon black, a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, an amorphous resin, and a release agent. A toner set for developing an electrostatic latent image, comprising: a crystalline polyester resin having a structural unit derived from a chain aliphatic dicarboxylic acid; an amorphous resin; and a toner other than the black toner. The structural unit derived from the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the black toner is represented by A (B), and the crystalline polyester contained in the toner other than the black toner. Depending on the electrostatic latent image developing toner set satisfying the above formula (1), where A (C) is the carbon number of the structural unit derived from the linear aliphatic dicarboxylic acid constituting the resin. Also found that the above problems can be solved, and completed the present invention.

  In the image forming method and the electrostatic latent image developing toner set according to the present invention, the carbon number of the linear aliphatic dicarboxylic acid component constituting the crystalline polyester resin contained in the black toner and the toner other than the black toner are included. The number of carbon atoms of the linear aliphatic dicarboxylic acid component constituting the crystalline polyester resin has a specific relationship. As a result, according to the present invention, there is provided a means capable of reducing the environment dependency of the density unevenness of the formed image while maintaining good low-temperature fixability.

  A first embodiment of the present invention includes a black toner comprising carbon black, a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, an amorphous resin, and a release agent. An image forming method using a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, an amorphous resin, and a toner other than the black toner, including a release agent. The structural unit derived from the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the black toner is represented by A (B), and the crystalline polyester resin contained in the toner other than the black toner is constituted. The image forming method satisfies the following formula (1), where A (C) is the carbon number of the structural unit derived from the linear aliphatic dicarboxylic acid.

  The second embodiment of the present invention is a black toner comprising carbon black, a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, an amorphous resin, and a release agent. An electrostatic latent image development comprising: a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid; an amorphous resin; and a toner other than the black toner. A toner set for a toner, wherein A (B) is the carbon number of the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the black toner, and is contained in toners other than the black toner The electrostatic latent image developing toner sensor satisfying the above formula (1) where A (C) is the carbon number of the structural unit derived from the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin. It is a door.

  Here, the toner set refers to a combination of toners that form different image forming layers when transferred onto a recording medium.

  According to the image forming method of the present invention, it is possible to reduce the environmental dependency of uneven density of the formed image while maintaining good low-temperature fixability. The same effect as described above can also be obtained by using the electrostatic latent image developing toner set according to the present invention. Although the mechanism of action by which the above-described effect can be obtained by such a configuration of the present invention is unknown, it is considered as follows.

  As disclosed in Patent Document 1, a toner containing a crystalline polyester resin is excellent in low-temperature fixability. However, the crystalline polyester resin has a low electrical resistance, and when used as a binder resin for toner, it also has a side that the chargeability of the toner is lowered. From such a point of view, in particular, the black toner cannot maintain insulation when an electric field is applied during transfer because carbon black used as a colorant has low electrical resistance (that is, high conductivity). As a result, it is considered that an image formed using black toner has uneven density because transferability is lowered. Such density unevenness tends to occur particularly in a high-temperature and high-humidity environment where chargeability tends to be low. On the other hand, toners other than black toner (color toners such as yellow toner, magenta toner, cyan toner, and clear toner) do not contain a highly conductive material such as carbon black, or the contained colorant contains a high electrical charge. Since it is resistant (that is, low conductivity), it has higher chargeability than black toner. Therefore, particularly in a low-temperature and low-humidity environment where chargeability tends to be high, the toner other than black toner has an excessively large charge amount (excessive charge), and tends to adhere electrostatically to the intermediate transfer member during transfer. End up. As a result, it is considered that it is difficult to uniformly transfer toner other than black toner when transferring the toner from the intermediate transfer member onto a recording medium such as paper.

  Therefore, as in Patent Document 1, when forming a full-color image using a toner containing a crystalline polyester resin, the charging property is highly dependent on the environment, and as a result, the density unevenness of the formed image depends on the environment. It is presumed to be high.

  On the other hand, the present inventors set the carbon number of the linear aliphatic dicarboxylic acid component, which is a structural unit of the crystalline polyester resin contained in each of the black toner and the toner other than the black toner, to a specific relationship. The inventors have found that the chargeability of black toner and color toner can be controlled. Furthermore, the inventors of the present invention can improve the charging property of black toner in a high temperature and high humidity environment by controlling the carbon number, and can suppress excessive charging of toners other than black toner in a low temperature and low humidity environment. The headline and the present invention were completed.

  In the present invention, the carbon number of the linear aliphatic dicarboxylic acid component (hereinafter also referred to as “A (B)”), which is a structural unit of the crystalline polyester resin contained in the black toner, is included in the toner other than the black toner. The linear aliphatic dicarboxylic acid component, which is a structural unit of the crystalline polyester resin, is larger in number than the carbon number (hereinafter also referred to as “A (C)”) (formula (1): A (B) > A (C)). As a result, the black toner is easier to incorporate the crystalline polyester resin into the toner particles (near the center) than other toners. As a result, a decrease in electrical resistance due to the crystalline polyester resin is suppressed particularly on the toner particle surface of the black toner in a high temperature and high humidity environment, and the charging property of the black toner can be improved. On the other hand, if the relationship of carbon number is A (B) ≦ A (C), the crystalline polyester resin is easily exposed on the toner particle surface in the black toner. The chargeability of the particle surface decreases. Therefore, when the black toner is transferred under the same transfer conditions as those of the toner other than the black toner, the charging property becomes insufficient particularly in a high temperature and high humidity environment, and density unevenness occurs in the formed image.

  Here, the ease of incorporation of the crystalline polyester resin into the toner particles can be considered as follows. Since the release agent contained in the toner particles together with the crystalline polyester resin is generally highly hydrophobic, it is easily taken into the toner particles (near the center). Here, the crystalline polyester resin composed of a linear aliphatic dicarboxylic acid having a large number of carbon atoms is an ester in the resin as compared with the crystalline polyester resin composed of a linear aliphatic dicarboxylic acid having a small number of carbon atoms. As a result of the lower group concentration, the hydrophobicity of the resin is increased. Therefore, the crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid having a large number of carbon atoms has a high affinity with a release agent due to its hydrophobicity, so that it is close to the surface of the toner particle. It is presumed that they tend to be taken into the interior more easily. On the other hand, the crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid having a small number of carbon atoms is not highly hydrophobic and therefore has a low affinity with a release agent, and the toner particles It is presumed that it tends to exist near the surface.

  Further, the carboxy group present at the terminal of the crystalline polyester resin interacts with the amorphous resin contained in the toner particles (for example, hydrogen bond or ionic interaction). Therefore, due to such interaction, the crystalline polyester resin tends to stay inside the toner particles in the toner particles.

  In addition, in the present invention, since the relationship of the carbon number satisfies the relationship of the above formula (1) (A (B)> A (C)), in the toner other than the black toner, The crystalline polyester resin is likely to be exposed on the toner particle surface. As a result, particularly in a low-temperature and low-humidity environment, the electric resistance of the toner particle surface other than the black toner is moderately lowered, and excessive charging can be suppressed. Therefore, toner other than black toner can be uniformly transferred, and unevenness in image density can be suppressed. On the other hand, when the carbon number relationship is A (B) ≦ A (C), the crystalline polyester resin is easily taken into the toner particles in the toner other than the black toner. Therefore, when toner other than black toner is transferred under the same transfer conditions as black toner, excessive charging on the surface of the toner particles, particularly in a low temperature and low humidity environment, cannot be suppressed, resulting in uneven image density.

  With the above mechanism, according to the present invention, by using a black toner and a toner other than the black toner satisfying the relationship of the above formula (1), the chargeability is appropriately controlled, and the black toner and the black under the same transfer conditions are used. A difference in transferability of toner other than toner can be reduced. As a result, it is possible to reduce the environmental dependency of uneven density of the formed image while maintaining the low-temperature fixability.

  Furthermore, the present inventors have also found in the course of study that according to the present invention, a good image density can be obtained without depending on the environment. As described above, when the black toner and the toner other than the black toner satisfy the above formula (1), the chargeability of the toner in a high temperature and high humidity environment and a low temperature and low humidity environment can be controlled. Therefore, according to the present invention, it is considered that a good image density can also be obtained without depending on the environment.

  In addition, the said mechanism is based on estimation and this invention is not restrict | limited to the said mechanism at all.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not limited only to the following embodiment. In this specification, “X to Y” indicating a range includes X and Y, and means “X or more and Y or less”. Unless otherwise specified, measurements of operation and physical properties were performed under conditions of room temperature (25 ° C.) / Relative humidity 40 to 50% RH.

  As described above, the image forming method and electrostatic latent image developing toner set according to the present invention are characterized by each toner. Therefore, in the following, first, the configuration of each toner will be described in detail.

<Toner (electrostatic latent image developing toner)>
The black toner according to the present invention includes carbon black as a colorant, a crystalline polyester resin, an amorphous resin, and a release agent. The toner other than the black toner according to the present invention includes a crystalline polyester resin, an amorphous resin, and a release agent. In the present specification, “toner other than black toner” refers to a toner that does not contain a black colorant as a colorant. In addition to a colored toner containing a colorant (color toner), a clear toner that does not contain a colorant. Including. The “toner” according to the present invention refers to an aggregate of “toner particles”.

[Toner particles]
The toner particles constituting the toner according to the present invention (referring to a toner other than black toner and black toner; the same applies hereinafter) are composed of a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, and an amorphous resin. And a mold release agent. The black toner particles contain carbon black in addition to these components. Further, the toner particles may contain other toner components such as a colorant and a charge control agent corresponding to each color, if necessary. Hereinafter, each component constituting the toner particles will be described.

≪Crystalline polyester resin≫
The toner particles contain a crystalline polyester resin as a binder resin. Therefore, at the time of heat fixing, the crystalline polyester resin and the amorphous resin are compatible with each other, and the low temperature fixability of the toner can be improved.

  The crystalline polyester resin is a polyester resin, and refers to a resin having a clear endothermic peak instead of a stepwise endothermic change in differential scanning calorimetry (DSC). The clear endothermic peak specifically means a peak whose half-value width of the endothermic peak is within 15 ° C. when measured at a rate of temperature increase of 10 ° C./min in differential scanning calorimetry (DSC). To do.

  The melting point (Tc) of the crystalline polyester resin is preferably 55 to 90 ° C, and more preferably 70 to 88 ° C. If the melting point of the crystalline polyester resin is within the range of 55 to 90 ° C, sufficient low-temperature fixability can be obtained. The melting point of the crystalline polyester resin can be controlled by the resin composition. The melting point (Tc) of the crystalline polyester resin can be measured by a differential calorimeter (DSC), and specifically is measured by the method described in the examples. Moreover, those skilled in the art can control the melting point by the resin composition.

  The crystalline polyester resin is obtained by a polycondensation reaction between a linear aliphatic dicarboxylic acid and a dihydric or higher alcohol (polyhydric alcohol). In addition, a divalent or higher carboxylic acid (polyvalent carboxylic acid) may also be used as long as the effects of the present invention are not impaired.

  Examples of linear aliphatic dicarboxylic acids and polyhydric alcohols used for the preparation of the crystalline polyester resin include the following.

(Linear aliphatic dicarboxylic acid)
Examples of the linear aliphatic dicarboxylic acid used in the production of the crystalline polyester resin contained in the toner according to the present invention include oxalic acid (ethanedioic acid), malonic acid (propanedioic acid), and succinic acid (butanedioic acid). ), Glutaric acid (pentanedioic acid), adipic acid (hexanedioic acid), pimelic acid (heptanedioic acid), suberic acid (octanedioic acid), azelaic acid (nonanedioic acid), sebacic acid (decanedioic acid), 1,9-nonanedicarboxylic acid (undecanedioic acid), 1,10-decanedicarboxylic acid (dodecanedioic acid), 1,11-undecanedicarboxylic acid (tridecanedioic acid), 1,12-dodecanedioic acid (tetradecanedioic acid) ), 1,13-tridecanedioic acid (pentadecanedioic acid), 1,14-tetradecanedioic acid (hexadecanedioic acid), etc. Can. These lower alkyl esters and acid anhydrides may also be used. The above polyvalent carboxylic acids may be used alone or in combination of two or more.

  Carbon number (A (B)) of linear aliphatic dicarboxylic acid used for preparation of crystalline polyester resin contained in black toner and linear fat used for preparation of crystalline polyester resin contained in toner other than black toner The group dicarboxylic acid (A (C)) satisfies the relationship of the above formula (1). In addition, said A (B) and A (C) are carbon number containing the carbon atom of a carboxy group.

  Here, when the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin is two or more, the carbon number of the linear aliphatic dicarboxylic acid having the largest content (mol%) is defined as A (B). , A (C). In addition, when there are two or more linear aliphatic dicarboxylic acids having the largest content (mol%), the carbon number of the linear aliphatic dicarboxylic acid having the largest carbon number is A (B), Define as A (C).

  Thus, for example, when the toner particles contain a crystalline polyester resin formed using 60 mol% malonic acid (3 carbon atoms) and 40 mol% adipic acid (6 carbon atoms) as the linear aliphatic dicarboxylic acid. , A (B) or A (C) is “3”. When the toner particles contain a crystalline polyester resin formed using 50 mol% malonic acid (carbon number 3) and 50 mol% adipic acid (carbon number 6) as the linear aliphatic dicarboxylic acid, (B) or A (C) is “6”. In addition, it was formed using 40 mol% malonic acid (3 carbon atoms), 40 mol% adipic acid (6 carbon atoms), and 20 mol% suberic acid (8 carbon atoms) as the linear aliphatic dicarboxylic acid. When the toner particles contain crystalline polyester resin, A (B) or A (C) is “6”.

  As long as the relationship of said Formula (1) is satisfy | filled, carbon number (A (B) and A (C)) of a linear aliphatic dicarboxylic acid is not restrict | limited in particular.

  Considering the availability, the ease of producing the crystalline polyester resin, the melting point of the obtained crystalline polyester resin, etc., the carbon number of the linear aliphatic dicarboxylic acid (A ( B) and A (C)) are preferably 20 or less. By setting A (B) and A (C) to 20 or less, the abundance of the crystalline polyester resin on the surface of the toner particles can be appropriately secured. As a result, the amorphous resin present on the surface of the toner particles can be appropriately plasticized to easily cause fusion between the toner particles and between the toner particles and a recording medium such as paper. Fixability can be demonstrated. Furthermore, A (B) and A (C) are more preferably 18 or less from the viewpoint of obtaining good low-temperature fixability.

  In the toner other than the black toner, the carbon number (A (C)) of the linear aliphatic dicarboxylic acid can provide appropriate chargeability without increasing the amount of the crystalline polyester resin on the toner particle surface. It is preferably 2 or more, and more preferably 4 or more. On the other hand, A (C) is preferably 10 or less from the viewpoint of appropriately exposing the crystalline polyester resin on the toner particle surface, suppressing excessive charging, and reducing the environmental dependency of uneven image density, It is more preferably 9 or less, and particularly preferably 6 or less.

  Furthermore, from the viewpoint of further reducing the environmental dependency of image density unevenness, it is preferable that the following expression (2) is satisfied, and it is more preferable that the following expression (3) is satisfied. Use of such a linear aliphatic dicarboxylic acid is also preferable from the viewpoint that a good image density can be obtained.

  From the above, the linear aliphatic dicarboxylic acid contained in the crystalline polyester resin contained in the toner other than the black toner is oxalic acid (ethanedioic acid), malonic acid (propanedioic acid), succinic acid (butanedioic acid), Preferably selected from the group consisting of glutaric acid (pentanedioic acid), adipic acid (hexanedioic acid), pimelic acid (heptanedioic acid), suberic acid (octanedioic acid) and azelaic acid (nonanedioic acid). More preferably, it is selected from the group consisting of acid (butanedioic acid), glutaric acid (pentanedioic acid) and adipic acid (hexanedioic acid).

  In the black toner, the carbon number (A (B)) of the linear aliphatic dicarboxylic acid is preferably 16 or less, and more preferably 14 or less, from the viewpoint of improving the low-temperature fixability. On the other hand, the exposure of the crystalline polyester resin on the toner particle surface is suppressed, and in particular, A (B) is preferably 8 or more, because the chargeability in a high temperature and high humidity environment is improved. And more preferred. Furthermore, from the viewpoint of reducing the environmental dependency of image density unevenness, it is preferable that the following expression (4) is satisfied, and it is more preferable that the following expression (5) is satisfied. Furthermore, the use of such a linear aliphatic dicarboxylic acid is also preferable in that a good image density can be obtained.

  As described above, the linear aliphatic dicarboxylic acids contained in the crystalline polyester resin contained in the black toner are sebacic acid (decanedioic acid), 1,9-nonanedicarboxylic acid (undecanedioic acid), and 1,10-decanedicarboxylic acid. Preferably selected from the group consisting of acids (dodecanedioic acid), 1,11-undecanedicarboxylic acid (tridecanedioic acid) and 1,12-dodecanedicarboxylic acid (tetradecanedioic acid), sebacic acid (decanedioic acid), More preferably, it is selected from the group consisting of 1,9-nonanedicarboxylic acid (undecanedioic acid) and 1,10-decanedicarboxylic acid (dodecanedioic acid).

  Moreover, as long as the effects of the present invention are not impaired, a divalent or higher carboxylic acid (polyvalent carboxylic acid) other than the linear aliphatic dicarboxylic acid may also be used. Examples of such polyvalent carboxylic acids include alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. In addition, polyvalent carboxylic acids other than divalent carboxylic acids may be used. Furthermore, these lower alkyl esters and acid anhydrides can also be used. The above polyvalent carboxylic acids may be used alone or in combination of two or more.

  However, in the black toner, from the viewpoint of facilitating the incorporation of the crystalline polyester resin into the toner particles and controlling the chargeability of the toner particles, the polyvalent dicarboxylic acid component constituting the crystalline polyester resin is It is preferable to be composed of only a linear aliphatic dicarboxylic acid satisfying the above formula (1). In addition, in the toner other than the black toner, the polyvalent dicarboxylic acid constituting the crystalline polyester resin from the viewpoint of easily exposing the crystalline polyester resin to the surface of the toner particles and easily controlling the chargeability of the toner particles. The component is preferably composed of only a linear aliphatic dicarboxylic acid satisfying the above formula (1).

  The content of the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the toner other than the black toner and the black toner is not particularly limited, but with respect to the total amount of monomers constituting the crystalline polyester resin, It is preferable in it being 10-65 mass%, and it is more preferable in it being 15-60 mass%. That is, the content of the constituent unit derived from the linear aliphatic dicarboxylic acid is preferably 10 to 65% by mass, and more preferably 15 to 60% by mass with respect to all the constituent units of the crystalline polyester resin. If it is in such a range, since it becomes easy to control the behavior of the crystalline polyester resin, it becomes easy to control the chargeability.

  In the relationship between the black toner and the toner other than black toner, A (B) and A (C) preferably satisfy the following formula (6), and more preferably satisfy the following formula (7). When these formulas are satisfied, good low-temperature fixability, reduction of environment dependency of uneven image density, and securing of good image density can be achieved in a balanced manner.

(Polyhydric alcohol)
The polyhydric alcohol used for the production of the crystalline polyester resin contained in the toner other than black toner and black toner is not particularly limited. Examples of the polyhydric alcohol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,7-hexane. Aliphatic diols such as butanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, 1,4-butenediol; glycerin, penta And trihydric or higher polyhydric alcohols such as erythritol, trimethylolpropane and sorbitol. Moreover, you may use these derivatives. The said polyhydric alcohol may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these, linear aliphatic diols are used as polyhydric alcohols from the viewpoint of controlling the behavior of crystalline polyester resin in toners other than black toner and black toner, and making it easier to control the chargeability of toner particles. Is preferred. From the same viewpoint, as the polyhydric alcohol, it is more preferable to use a linear aliphatic diol having 4 to 20 carbon atoms, and it is even more preferable to use a linear aliphatic diol having 6 to 16 carbon atoms. It is particularly preferable to use a linear aliphatic diol having a number of 8 or more and 14 or less.

  Further, the carbon number of the linear aliphatic diol constituting the crystalline polyester resin in the toner other than the black toner and the black toner (these definitions are defined as A (B) and A (C ) Is defined as X (B) and X (C), respectively, the above A (B) and A (C) satisfy the relationship of the following formulas (8) and (9): preferable. When satisfying such a relationship, it is possible to reduce the environmental dependency of uneven density while maintaining good low-temperature fixability. Also, a good image density can be obtained.

  Furthermore, from the same viewpoint, it is preferable that the above X (B) and X (C) satisfy the following formulas (10) and (11).

  The method for synthesizing the crystalline polyester resin using the monomer is not particularly limited, and the linear aliphatic dicarboxylic acid and the polyhydric alcohol are polycondensed (esterified) using a known esterification catalyst. Thus, the resin can be formed.

  Catalysts that can be used in the production include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum, zinc, manganese, antimony, titanium, tin, zirconium, germanium, and the like Metal compounds; phosphorous acid compounds; phosphoric acid compounds; and amine compounds. Considering availability, dibutyltin oxide, tin octylate, tin dioctylate, salts thereof, tetranormal butyl titanate (tetrabutyl orthotitanate), tetraisopropyl titanate (titanium tetraisopropoxide), tetramethyl titanate, etc. Is preferably used. These may be used alone or in admixture of two or more.

  The temperature of polycondensation (esterification) is not particularly limited, but is preferably 150 to 250 ° C. The time for polycondensation (esterification) is not particularly limited, but is preferably 0.5 to 15 hours. During the polycondensation, the reaction system may be depressurized as necessary.

  The number average molecular weight (Mn) of the crystalline polyester resin is not particularly limited, but is preferably in the range of 1,500 to 25,000, and more preferably in the range of 3,000 to 20,000. . Within such a range, the low-temperature fixability can be further improved. The number average molecular weight (Mn) can be measured by gel permeation chromatography (GPC). Specifically, it can be measured by the method described in Examples.

  In the present invention, the black toner and the toner other than the black toner contain an amorphous resin as a binder resin in addition to the crystalline polyester resin. The content of the crystalline polyester resin in the toner other than the black toner and the black toner is preferably 1 to 30% by mass, more preferably 3 to 20% by mass with respect to the whole binder resin. It is especially preferable that it is -17 mass%. When the content of the crystalline polyester resin is 1% by mass or more, it is appropriately plasticized by compatibility with the amorphous resin, and the low-temperature fixability is easily improved. On the other hand, when the content of the crystalline polyester resin is 30% by mass or less, in the black toner, the crystalline polyester resin is difficult to be exposed on the surface of the toner particles, so that the charging property is further improved, and in a high temperature and high humidity environment. Even if it exists, the image density unevenness is suppressed, and the image density is also improved.

  Similarly, from the viewpoint of improving low-temperature fixability and suppressing environmental dependency of uneven image density, the content of the crystalline polyester resin in the toner other than the black toner and the black toner is different from that of the crystalline polyester resin and the amorphous polyester, respectively. 1 to 30% by mass, more preferably 3 to 20% by mass, and particularly preferably 6 to 15% by mass with respect to the total mass of the total of the functional resin and the release agent. Within such a range, the low-temperature fixability is excellent and the density of the formed image is also improved.

  The structure of the structural component (structural unit) of the crystalline polyester resin and the content (ratio) of each structural component (each structural unit) should be specified by, for example, NMR measurement or methylation reaction Py-GC / MS measurement. Can do.

≪Amorphous resin≫
The toner particles contain an amorphous resin as a binder resin. The amorphous resin is preferably the main component of the binder resin contained in each toner. When the binder resin contains the amorphous resin as a main component, the amorphous resin is likely to be present on the toner particle surface. As a result, the chargeability of the toner particles can be improved due to the high electrical resistance of the amorphous resin. Here, the “main component” means a resin having the highest content ratio among the binder resins. The amorphous resin is preferably 50% by mass or more, more preferably 70 to 99% by mass, still more preferably 80 to 97% by mass, and 83 to 94% by mass with respect to the entire binder resin. % Is particularly preferred. The content of the amorphous resin is preferably 65 to 95% by mass, and 75 to 90% by mass with respect to the total mass of the crystalline polyester resin, the amorphous resin, and the release agent. Is more preferable, and 80 to 88% by mass is particularly preferable. Within such a range, the low-temperature fixability is excellent and the density of the formed image is also improved.

  Here, the amorphous resin is a resin having a relatively high glass transition temperature (Tg) without having a melting point when differential scanning calorimetry (DSC) is performed. At this time, the glass transition temperature (Tg) is preferably 30 to 80 ° C, and particularly preferably 40 to 65 ° C. In addition, a glass transition temperature (Tg) can be measured with a differential calorimeter (DSC), and specifically, is measured by the method described in the examples. Those skilled in the art can control the glass transition temperature by controlling the resin composition.

  As the amorphous resin, a conventionally known amorphous resin in this technical field can be used, and among them, an amorphous polyester resin or a vinyl resin is preferable, and these resins may be mixed and used. Among these, the amorphous resin preferably contains a vinyl resin from the viewpoint of excellent environmental stability of the charge amount.

(Vinyl resin)
The vinyl resin is a resin obtained by polymerization using at least a vinyl monomer. Specific examples of the vinyl resin include an acrylic resin and a styrene acrylic copolymer resin (styrene acrylic resin).

  Especially, as a vinyl resin, the styrene acrylic copolymer resin formed using a styrene monomer and a (meth) acrylic acid ester monomer is preferable. That is, it is preferable that the amorphous resin contained in the black toner and the toner other than the black toner according to the present invention each contain a styrene acrylic resin. The styrene acrylic copolymer resin is particularly suitable as the amorphous resin according to the present invention because it is excellent in environmental stability of the charge amount. The vinyl resins may be used alone or in combination of two or more.

  As the vinyl monomer forming the vinyl resin, one or more selected from the following can be used.

(1) Styrene monomer Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert- Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, and derivatives thereof.

(2) (Meth) acrylic acid ester monomer (Meth) methyl acrylate, (meth) ethyl acrylate, n-butyl (meth) acrylate (n-butyl (meth) acrylate), isopropyl (meth) acrylate , Isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, ( Such as phenyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and derivatives thereof.

(3) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate and the like.

(4) Vinyl ethers Vinyl methyl ether, vinyl ethyl ether and the like.

(5) Vinyl ketones Vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone and the like.

(6) N-vinyl compounds N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like.

(7) Others Vinyl compounds such as vinyl naphthalene and vinyl pyridine, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

  Moreover, as a vinyl monomer, it is preferable to use the monomer which has ionic dissociation groups, such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group, for example. Specifically, there are the following.

  Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester. Examples of the monomer having a sulfonic acid group include styrene sulfonic acid, allyl sulfosuccinic acid, and 2-acrylamido-2-methylpropane sulfonic acid. Furthermore, examples of the monomer having a phosphate group include acid phosphooxyethyl methacrylate.

  Furthermore, it is good also as a vinyl resin which uses polyfunctional vinyls as a vinyl monomer, and has a crosslinked structure. Polyfunctional vinyls include divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol Examples include diacrylate.

  The method for producing the vinyl resin is not particularly limited, and bulk polymerization, solution using any polymerization initiator such as peroxide, persulfate, persulfide, azo compound and the like usually used for polymerization of the above monomer. Examples of the polymerization method include polymerization, emulsion polymerization, mini-emulsion, and dispersion polymerization. Moreover, the chain transfer agent generally used can be used in order to adjust molecular weight. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans and mercapto fatty acid esters.

  Moreover, it is preferable that the molecular weight measured by the gel permeation chromatography (GPC) of a vinyl resin is 10,000-100,000 in a weight average molecular weight (Mw).

  In the present invention, the amorphous resin contained in the black toner and each color toner preferably contains a vinyl resin, and more preferably contains a styrene acrylic resin. Vinyl resins (especially styrene acrylic resins) have less polar functional groups and lower hygroscopicity than amorphous polyester resins, so that transferability in a high-temperature and high-humidity environment is good. Therefore, it is easy to reduce the environmental dependence of the image density unevenness. In addition, a good image density can be obtained without depending on the environment. The content of the styrene acrylic resin in the amorphous resin is not particularly limited. As described above, from the viewpoint of reducing the environmental dependency of image density unevenness, the content of the styrene acrylic resin is preferably 50% by mass or more, and more than 80% by mass with respect to the total amount of the amorphous resin. Is more preferable, 90% by mass or more is particularly preferable, and 100% by mass is particularly preferable.

≪Release agent≫
The toner particles of the toner other than the black toner and the black toner used in the present invention each contain a release agent (wax).

  Examples of the release agent include hydrocarbon waxes such as low molecular weight polyethylene wax, low molecular weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, and paraffin wax, carnauba wax, pentaerythritol behenate, and behenyl behenate. And ester waxes such as behenyl citrate. These can be used alone or in combination of two or more.

  Among these, in order to facilitate the presence of the crystalline polyester resin in the toner particles of the black toner and to improve the chargeability, it is preferable to use hydrocarbon waxes having high hydrophobicity as the release agent.

  The content of the release agent is preferably 2 to 20% by mass, more preferably 3 to 18% by mass, and particularly preferably 5 to 15% by mass with respect to the total amount of the binder resin. The content of the release agent is preferably 1 to 15% by mass with respect to the total mass of the crystalline polyester resin, the amorphous resin, and the release agent, and is 4 to 13% by mass. More preferably, it is more preferably 5 to 10% by mass. Within such a range, the low-temperature fixability is excellent and the density of the formed image is also improved.

  Further, the melting point of the release agent is preferably 50 to 95 ° C. from the viewpoints of low-temperature fixability and releasability of the toner in the electrophotographic system.

≪Colorant≫
The black toner used in the present invention contains carbon black as a colorant in addition to a binder resin (crystalline polyester resin and amorphous resin) and a release agent. Among toners other than black toner, color toners (colored toners such as yellow toner, magenta toner, and cyan toner) are added to the binder resin (crystalline polyester resin and amorphous resin) and the release agent in addition to each color. Depending on the colorant.

  That is, another form of the image forming method according to the present invention is a form in which the toner other than the black toner is a colored toner. Furthermore, another form of the image forming method according to the present invention is a form in which the toner other than the black toner is a yellow toner, a magenta toner, and a cyan toner.

  Colorants (especially organic pigments) used for colored toners such as yellow toner, magenta toner, and cyan toner each have a relatively high electric resistance value, so that the amount of charge on the surface of the toner particles becomes large in a low temperature and low humidity environment. As a result, transferability is lowered. However, according to the present invention, even when such a colorant is used, the crystalline polyester resin is present in the vicinity of the surface of the toner particles, so that the chargeability in a low temperature and low humidity environment is appropriately reduced. It is possible to reduce the environment dependence of the image density unevenness. In addition, a good image density can be secured.

  Hereinafter, the types of colorants for each color will be described.

(Black colorant)
The black toner used in the present invention contains carbon black as a colorant. Although carbon black has a low electrical resistance value, according to the present invention, even when such a colorant is used, the chargeability can be improved particularly in a high-temperature and high-humidity environment. Uneven environmental dependency can be reduced. As the carbon black, channel black, furnace black, acetylene black, thermal black, or lamp black is used.

  Further, the black toner may further contain a magnetic material, a dye, other pigments, and the like in addition to carbon black. As the magnetic material, a ferromagnetic metal such as iron, nickel, or cobalt, an alloy containing these metals, a compound of a ferromagnetic metal such as ferrite or magnetite, or the like can be used. As other pigments, titanium black, aniline black and the like can be used.

(Yellow colorant)
The colorant for orange or yellow used for the yellow toner is not particularly limited. For example, C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185. Examples of the dye include C.I. I. Solvent Yellow 19, C.I. I. Solvent Yellow 44, C.I. I. Solvent Yellow 77, C.I. I. Solvent Yellow 79, C.I. I. Solvent Yellow 81, C.I. I. Solvent Yellow 82, C.I. I. Solvent Yellow 93, C.I. I. Solvent Yellow 98, C.I. I. Solvent Yellow 103, C.I. I. Solvent Yellow 104, C.I. I. Solvent Yellow 112, C.I. I. Solvent yellow 162 etc. are mentioned. These colorants may be used alone or in combination of two or more.

(Magenta colorant)
The colorant for magenta or red used in the magenta toner is not particularly limited. For example, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48; 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment Red 57; 1, Pigment Red 81; 4, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 150, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, pigment red 184, C.I. I. Pigment red 222, C.I. I. Pigment red 238, C.I. I. And CI Pigment Red 269. Examples of the dye include C.I. I. Solvent Red 1, Solvent Red 11, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Solvent Red 58, C.I. I. Solvent Red 68, C.I. I. Solvent Red 111, C.I. I. Solvent Red 122 etc. are mentioned. These colorants may be used alone or in combination of two or more.

(Cyan colorant)
The colorant for green or cyan used for the cyan toner is not particularly limited. For example, as an organic pigment, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. Pigment blue 76, C.I. I. And CI Pigment Green 7. Examples of the dye include C.I. I. Solvent Blue 25, C.I. I. Solvent Blue 36, C.I. I. Solvent Blue 69, C.I. I. Solvent Blue 70, C.I. I. Solvent Blue 93, C.I. I. Solvent Blue 95 etc. are mentioned. These colorants may be used alone or in combination of two or more.

(Colorant content)
The content of each colorant is preferably 1 to 30 parts by mass and more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the toner particles. Also, within such a range, color reproducibility of the image can be ensured.

(Colorant particle size)
Further, the size of the colorant (particle) is not particularly limited, but the volume-based median diameter is preferably 10 to 1000 nm, more preferably 50 to 500 nm, and particularly preferably 80 to 300 nm. . Within such a range, high color reproducibility can be obtained, and it is preferable in that it is suitable for forming a small diameter toner required for high image quality. The volume-based median diameter of the colorant (particle) can be measured using, for example, a Microtrac (registered trademark, hereinafter the same) particle size distribution measuring device “UPA-150” (manufactured by Nikkiso Co., Ltd.).

≪Charge control agent≫
The toner particles of the black toner and color toner used in the present invention may contain other internal additives as necessary. Examples of such an internal additive include a charge control agent. Examples of charge control agents include metal complexes of salicylic acid derivatives with zinc or aluminum (salicylic acid metal complexes), calixarene compounds, organic boron compounds, and fluorine-containing quaternary ammonium salt compounds.

  The content of the charge control agent is usually preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the binder resin in the toner.

≪Toner particle morphology≫
The toner particles may have a so-called single layer structure, or may have a core-shell structure (a form in which a resin forming a shell layer is aggregated and fused on the surface of the core particles). Good. The core-shell structure is not limited to the structure in which the shell layer completely covers the core particles. For example, the shell layer does not completely cover the core particles, and the core particles are exposed in some places. Including those that are.

  In addition, from the viewpoint of improving the chargeability in a high temperature and high humidity environment, the black toner according to the present invention is not exposed to the surface of the toner particles, the crystalline polyester resin is contained inside the toner particles, and is amorphous. It is preferable that the functional resin is exposed on the surface of the toner particles. On the other hand, from the viewpoint of improving transferability in a low-temperature and low-humidity environment and reducing uneven image density, the toner other than the black toner according to the present invention is preferably in a form in which the crystalline polyester resin is exposed on the surface of the toner particles. . Each form of the toner particles of the black toner and the toner other than the black toner can be controlled by the number of carbon atoms of the linear aliphatic dicarboxylic acid forming the crystalline polyester resin as described above. As will be described later, when the toner particles are produced by the emulsion aggregation method, the form of the toner particles can also be controlled by the timing of addition of each resin.

  The form of the above-described toner particles (the cross-sectional structure of the core-shell structure and the position where the crystalline polyester resin is present) can be determined using known means such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM). It is possible to confirm.

≪Average circularity of toner particles≫
From the viewpoint of improving low-temperature fixability, the average circularity of the toner particles is preferably 0.920 to 1.000, and more preferably 0.940 to 0.995. Here, the average circularity is a value measured using “FPIA-2100” (manufactured by Sysmex). Specifically, the toner particles are moistened with an aqueous surfactant solution, and ultrasonic dispersion is performed for 1 minute. After dispersion, HPFP detection is performed in the measurement condition HPF (high magnification imaging) mode using “FPIA-2100”. Measurement is performed at an appropriate concentration of several thousand pieces. The circularity is calculated by the following formula.

Circularity = (perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)
The average circularity is an arithmetic average value obtained by adding the circularity of each particle and dividing by the total number of particles measured.

≪Toner particle size≫
Regarding the particle diameter of the toner particles, the volume-based median diameter (D50) is preferably 3 to 10 μm. By setting the volume-based median diameter within the above range, reproducibility of fine lines and high-quality photographic images can be achieved, and toner consumption can be reduced as compared to the case of using large-diameter toner. be able to. Also, toner fluidity can be secured. Here, the volume-based median diameter (D50) of the toner particles is measured and calculated using, for example, a device in which a computer system for data processing is connected to “Coulter Multisizer 3” (manufactured by Beckman Coulter). be able to.

  The volume-based median diameter of the toner particles can be controlled by controlling the concentration of the aggregating agent, the amount of the solvent added during the agglomeration / fusion process during the toner production described later, the fusing time, and the composition of the resin component. it can.

≪External additive≫
The black toner and the toner other than the black toner according to the present invention are external additives such as known inorganic particles and organic particles, lubricants and the like on the toner particle surface from the viewpoint of improving charging performance, fluidity, or cleaning properties. It is preferable to contain as. Various external additives may be used in combination. Examples of the particles include inorganic oxide particles such as silica particles, alumina particles and titania particles, inorganic stearate compound particles such as aluminum stearate particles and zinc stearate particles, or strontium titanate particles and zinc titanate particles. And inorganic titanic acid compound particles. In addition, as the lubricant, zinc stearate, such as zinc, aluminum, copper, magnesium, calcium, zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as salts, zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc. These external additives may be subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil, or the like from the viewpoint of heat-resistant storage stability and environmental stability. The external additives can be used alone or in combination of two or more.

  Among these, inorganic oxide particles such as silica particles (spherical silica), alumina particles, and titania particles are preferably used as the external additive.

  The amount of the external additive added (the total amount when two or more types are used) is preferably 0.05 to 5% by mass, more preferably 0, based on 100% by mass of the total toner including the external additive. 0.1 to 3% by mass.

  The particle size of the external additive is not particularly limited, but particles such as inorganic fine particles having a number average primary particle size of about 2 to 800 nm and organic fine particles having a number average primary particle size of about 10 to 2000 nm are preferable. In this specification, “number average primary particle diameter” is a value obtained by binarizing a scanning electron micrograph of external additive particles, calculating a horizontal ferret diameter for 10,000 particles, and taking the average. Say.

[Toner Production Method]
Hereinafter, a method for producing black toner, colored toner and clear toner (electrostatic latent image developing toner) used in the present invention will be described.

  The method for producing the toner used in the present invention is not particularly limited, and examples thereof include known methods such as a kneading and pulverizing method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension method, a polyester elongation method, and a dispersion polymerization method. .

  Among these, it is preferable to employ the emulsion aggregation method from the viewpoint of the uniformity of particle diameter, the controllability of the shape, and the ease of forming the core-shell structure. Also, from the viewpoint that it is easy to control the crystalline polyester resin in the toner particles so as to be in a desired position by utilizing the hydrophobicity of the crystalline polyester resin and the release agent, it is preferable to use the emulsion aggregation method. . Hereinafter, the emulsion aggregation method will be described.

≪Emulsion aggregation≫
In the emulsion aggregation method, a dispersion of binder resin particles (hereinafter also referred to as “binder resin particles”) dispersed with a surfactant or a dispersion stabilizer is used as a release agent particle (hereinafter referred to as “release”). In this method, toner particles are produced by controlling the shape by mixing with a dispersion liquid (also referred to as “agent particles”), aggregating until a desired particle diameter is obtained, and further fusing the binder resin particles together. . Here, the binder resin particles may optionally contain a colorant, a charge control agent, and the like. Further, a colorant may be added in the form of a dispersion of colorant particles to the dispersion of binder resin particles and the dispersion of release agent particles.

When producing a toner for developing an electrostatic latent image by an emulsion aggregation method, a production method according to a preferred embodiment is:
(A) A step of preparing a crystalline polyester resin particle dispersion, an amorphous resin particle dispersion, a release agent particle dispersion, and, if necessary, a colorant particle dispersion (hereinafter also referred to as a preparation step).
(B) A step of aggregating and fusing the crystalline polyester resin particle dispersion, the amorphous resin particle dispersion and the release agent particle dispersion, and, if necessary, the colorant particle dispersion (hereinafter referred to as aggregation) (Also referred to as fusion process)
including.

  Hereinafter, steps (a) to (b) and steps (c) to (g) optionally performed in addition to these steps will be described in detail.

(A) Preparation Step Step (a) includes a crystalline polyester resin particle dispersion preparation step, an amorphous resin particle dispersion preparation step, a release agent particle dispersion preparation step, and, if necessary, a colorant particle dispersion. Including a preparation step.

(A-1) Crystalline polyester resin particle dispersion preparation step In the crystalline polyester resin particle dispersion preparation step, a crystalline polyester resin constituting a binder resin is synthesized, and the crystalline polyester resin is finely divided in an aqueous medium. And preparing a dispersion of crystalline polyester resin particles.

  Since the manufacturing method of crystalline polyester resin is as having described above, description is abbreviate | omitted here.

  The crystalline polyester resin particle dispersion is, for example, a method in which a dispersion treatment is performed in an aqueous medium without using a solvent, or the crystalline polyester resin is dissolved in a solvent such as ethyl acetate or methyl ethyl ketone to form a solution. Examples thereof include a method of performing a solvent removal treatment after emulsifying and dispersing the solution in an aqueous medium.

  In the present invention, the “aqueous medium” refers to a medium containing at least 50% by mass of water, and examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, Examples include isopropanol, acetone, dimethylformamide, methyl cellosolve, and tetrahydrofuran. Of these, it is preferable to use an alcoholic organic solvent such as methanol, ethanol, or isopropanol, which is an organic solvent that does not dissolve the resin. Preferably, only water is used as the aqueous medium.

  When the crystalline polyester resin contains a carboxy group in its structure, ammonia, sodium hydroxide, or the like may be added in order to ionically dissociate the carboxy group and stably emulsify it in the aqueous phase to facilitate the emulsification. Good. Furthermore, a dispersion stabilizer may be dissolved in the aqueous medium, and a surfactant or resin particles may be added for the purpose of improving the dispersion stability of the oil droplets.

  As the dispersion stabilizer, known ones can be used. For example, it is preferable to use one that is soluble in acid or alkali, such as tricalcium phosphate, or from an environmental point of view, depending on the enzyme. It is preferable to use a decomposable one. As the surfactant, known anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants can be used. Examples of the resin particles for improving dispersion stability include polymethyl methacrylate resin particles, polystyrene resin particles, and polystyrene-acrylonitrile resin particles.

  Such a dispersion treatment can be performed using mechanical energy, and the disperser is not particularly limited, and is a homogenizer, a low-speed shear disperser, a high-speed shear disperser, a friction disperser. Machine, high-pressure jet disperser, ultrasonic disperser, high-pressure impact disperser, optimizer, and emulsifier disperser.

  In dispersing, it is preferable to heat the solution. Although heating conditions are not specifically limited, Usually, it is about 60-200 degreeC.

  The volume-based median diameter of the crystalline polyester resin particles in the prepared crystalline polyester resin particle dispersion is preferably 60 to 1000 nm, and more preferably 80 to 500 nm. The median diameter can be controlled by the magnitude of mechanical energy during emulsification dispersion.

  Further, the content of the crystalline polyester resin particles in the crystalline polyester resin particle dispersion is preferably in the range of 10 to 50% by mass and more preferably in the range of 15 to 40% by mass with respect to the entire dispersion. Within such a range, the spread of the particle size distribution can be suppressed and the toner characteristics can be improved.

(A-2) Amorphous resin particle dispersion preparation step In the amorphous resin particle dispersion preparation step, an aqueous dispersion of an amorphous resin is prepared. As described above, since a vinyl resin is preferably used as the amorphous resin, a method for preparing a vinyl resin particle dispersion (preparation step) will be described below.

  In the step of preparing the vinyl resin particle dispersion, an aqueous dispersion of vinyl resin is prepared. For example, when a vinyl resin is obtained by performing emulsion polymerization in an aqueous medium, the liquid after the polymerization reaction can be used as it is as a vinyl resin particle dispersion.

  Alternatively, a method may be used in which the isolated vinyl resin is pulverized as necessary, and then the vinyl resin is dispersed in an aqueous medium using an ultrasonic disperser in the presence of a surfactant. Examples of the aqueous medium and the surfactant are the same as in the above (a-1), and thus the description thereof is omitted here.

  The volume-based median diameter of the vinyl resin particles in the vinyl resin particle dispersion is preferably 60 to 1000 nm, and preferably in the range of 80 to 500 nm. The median diameter can be controlled by the magnitude of mechanical energy during polymerization.

  The content of the vinyl resin particles in the vinyl resin particle dispersion is preferably in the range of 10 to 50 mass%, more preferably in the range of 15 to 40 mass% with respect to the entire dispersion. Within such a range, the spread of the particle size distribution can be suppressed and the toner characteristics can be improved.

(A-3) Release Agent Particle Dispersion Preparation Step The release agent particle dispersion preparation step is a step of preparing a release agent particle dispersion by dispersing the release agent in the form of fine particles in an aqueous medium. .

  The aqueous medium is as described in (a-1) above, and a surfactant or resin particles may be added to the aqueous medium for the purpose of improving dispersion stability.

  The release agent can be dispersed using mechanical energy. Such a disperser is not particularly limited, and those described in (a-1) above can be used. .

  The volume-based median diameter of the release agent particles in the release agent particle dispersion is preferably in the range of 10 to 300 nm.

  The content of the release agent particles in the release agent particle dispersion is preferably in the range of 5 to 45% by mass and more preferably in the range of 8 to 30% by mass with respect to the entire dispersion. Within such a range, effects of preventing hot offset and ensuring separability can be obtained.

(A-4) Colorant Particle Dispersion Preparation Step The colorant particle dispersion preparation step is a step of preparing a dispersion of colorant particles by dispersing a colorant in a fine particle form in an aqueous medium. It is preferable to carry out it when producing black toner and colored toner.

  Since the aqueous medium is as described in (a-1) above, description thereof is omitted here. In this aqueous medium, a surfactant or resin particles may be added for the purpose of improving dispersion stability.

  The dispersion of the colorant can be performed by a disperser using mechanical energy, and the disperser is not particularly limited, and the one described in (a-1) above may be used. it can.

  The volume-based median diameter of the colorant particles in the colorant particle dispersion is preferably in the range of 10 to 300 nm.

  The content of the colorant in the colorant particle dispersion is preferably in the range of 5 to 45% by mass, more preferably in the range of 10 to 30% by mass with respect to the entire dispersion. Within such a range, there is an effect of ensuring color reproducibility.

(B) Aggregation / fusion process In this aggregation / fusion process, the above-described crystalline polyester resin particles, amorphous resin particles, release agent particles, and, if necessary, colorant particles are aggregated in an aqueous medium. And agglomerating these particles at the same time.

  In this step, first, a crystalline polyester resin particle dispersion, an amorphous resin particle dispersion, a release agent particle dispersion, and, if necessary, a colorant particle dispersion are mixed, and these particles are mixed in an aqueous medium. Disperse. When manufacturing a clear toner, the aggregation / fusion process is performed without adding the colorant particle dispersion.

  Next, after adding a flocculant, the aggregation is advanced by heating at a temperature equal to or higher than the glass transition point of the amorphous resin particles, and at the same time, the resin particles are fused.

  The flocculant is not particularly limited, but a flocculant selected from metal salts such as alkali metal salts and Group 2 metal salts is preferably used. Examples of the metal salt include monovalent metal salts such as sodium, potassium, and lithium; divalent metal salts such as calcium, magnesium, manganese, and copper; and trivalent metal salts such as iron and aluminum. Specific examples of the metal salt include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, and aluminum sulfate. Among these, it is particularly preferable to use a divalent or trivalent metal salt because aggregation can be progressed in a smaller amount. These flocculants can be used alone or in combination of two or more.

  The amount of the flocculant used is not particularly limited, but is preferably 0.1 to 20 parts by weight, more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the solid content of the binder resin constituting the toner particles. Part.

  In the aggregating step, it is preferable to quickly raise the temperature by heating after adding the aggregating agent, and the rate of temperature rise is preferably 0.05 ° C./min or more. The upper limit of the heating rate is not particularly limited, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid progress of fusion. Further, after the dispersion liquid for agglomeration reaches a desired temperature, the temperature of the dispersion liquid for aggregation is maintained for a certain period of time, preferably until the volume-based median diameter is 4.5 to 7.0 μm. It is important to continue.

(C) Aging step This step is carried out as necessary, and in this aging step, the associated particles obtained by the aggregation / fusion step are aged to a desired shape by thermal energy. An aging process for forming toner particles is performed.

  Specifically, the aging treatment is performed by heating and stirring the system in which the associated particles are dispersed, and adjusting the heating temperature, the stirring speed, the heating time, and the like until the shape of the associated particles reaches a desired circularity. Is called.

(D) Cooling Step This step is a step of cooling the toner particle dispersion. As a condition for the cooling treatment, it is preferable to cool at a cooling rate of 1 to 20 ° C./min. The specific method of the cooling treatment is not particularly limited, and examples include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, a method of cooling by directly introducing cold water into the reaction system, and the like. it can.

(E) Filtration / Washing Step In this step, the toner particles are solid-liquid separated from the cooled dispersion of toner particles, and the toner cake obtained by solid-liquid separation (the toner particles in a wet state are aggregated in a cake form) This is a step of removing adhering substances such as a surfactant and an aggregating agent from the aggregate).

  The solid-liquid separation is not particularly limited, and a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press, or the like can be used.

(F) Drying step This step is a step of drying the washed toner cake, and can be performed according to a drying step in a generally-known method for producing toner particles.

  Specifically, examples of the dryer used for drying the toner cake include a spray dryer, a vacuum freeze dryer, and a vacuum dryer, and a stationary shelf dryer, a mobile shelf dryer, a fluidized bed, and the like. It is preferable to use a dryer, a rotary dryer, a stirring dryer or the like.

(G) External additive addition step This step is a step that is performed as necessary when an external additive is added to the toner particles.

  As an external additive mixing apparatus, a mechanical mixing apparatus such as a Henschel mixer, a coffee mill, or a sample mill can be used.

<Developer>
Each of the black toner and the toner other than black toner can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When the toner is used as a two-component developer, the carrier includes magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead. In particular, ferrite particles are preferable. Further, as the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a dispersion type carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.

  The volume average particle diameter of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm. The volume average particle diameter of the carrier can be typically measured by a laser diffraction type particle size distribution measuring apparatus “HELOS” (manufactured by Sympathic) equipped with a wet disperser.

  The two-component developer can be produced by mixing the carrier and the toner using a mixing device. Examples of the mixing device include a Henschel mixer, a Nauter mixer, and a V-type mixer.

  The blending amount of the toner when preparing the two-component developer is preferably 1 to 10% by mass with respect to 100% by mass of the total of the carrier and the toner.

<Image forming method>
The image forming method of the present invention includes forming an image forming layer on a recording medium using the toner (electrostatic latent image developing toner). That is, the present invention is derived from a black toner containing carbon black, a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, and an amorphous resin, and a linear aliphatic dicarboxylic acid. An electrostatic latent image developing toner set comprising a crystalline polyester resin having a structural unit and an amorphous resin, and a toner other than the black toner, wherein the crystalline property contained in the black toner The carbon number of the structural unit derived from the linear aliphatic dicarboxylic acid constituting the polyester resin is A (B), and derived from the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the toner other than the black toner. There is also provided a toner set for developing an electrostatic latent image that satisfies the following formula (1), where A (C) is the carbon number of the constituent unit.

  The image forming method according to the present invention is a method using black toner and a toner other than black (for example, yellow toner, magenta toner, cyan toner, clear toner, etc.), and is preferably used for a full-color image forming method. it can. In the full-color image forming method, four types of color developing devices for yellow, magenta, cyan, and black, and one electrostatic latent image carrier (also referred to as “electrophotographic photosensitive member” or simply “photosensitive member”) And a tandem type image forming apparatus in which a color developing device for each color and an image forming unit having an electrostatic latent image carrier are mounted for each color. Any image forming method such as a method used can be used. When clear toner is further used, five types of developing devices for yellow, magenta, cyan, black, and clear and one electrostatic latent image carrier (“electrophotographic photosensitive member” or simply “photosensitive”) are used. A method using a five-cycle type image forming apparatus constituted by, and a developing device for each color including clear toner and an image forming unit having an electrostatic latent image carrier are mounted for each color. An image forming method such as a method using a tandem image forming apparatus can be used.

  As an image forming method, an image forming method including a fixing step by a heat and pressure fixing method capable of applying pressure and heating can be preferably exemplified.

  Specifically, in this image forming method, the toner is used, for example, an electrostatic latent image formed on a photoreceptor is developed to obtain a toner image, and the toner image is applied to an image support. After the transfer, the toner image transferred onto the image support is fixed on the image support by a fixing process using a thermal pressure fixing method, whereby a printed matter on which a visible image is formed can be obtained.

  The application of pressure and heating in the fixing step are preferably simultaneous, and the pressure may be applied first and then heated.

  As described above, in the image forming method according to the present invention, the carbon number of the linear aliphatic dicarboxylic acid component constituting the crystalline polyester resin in the black toner and the toner other than the black toner (colored toner and clear toner) used is as follows. Have a specific relationship. By using such a toner, the chargeability of the black toner in a high temperature and high humidity environment is improved while maintaining good low temperature fixability, and the transferability of the toner other than the black toner in a low temperature and low humidity environment is improved. Can be good. As a result, an image having excellent image density uniformity can be formed without depending on the environment. Furthermore, the image density in the obtained image is also improved.

  Further, the image forming method of the present invention is suitably used in a thermal pressure fixing type image forming method. As the heat-pressure fixing type fixing device used in the image forming method of the present invention, various known devices can be adopted. Hereinafter, a heat roller type fixing device and a belt heating type fixing device will be described as the thermal pressure fixing device.

(I) Heat roller type fixing device Generally, a heat roller type fixing device has a pair of rollers including a heating roller and a pressure roller in contact with the heating roller. In the fixing device, when the pressure roller is deformed by the pressure applied between the heating roller and the pressure roller, a so-called fixing nip portion is formed in the deformed portion.

  The heating roller is generally formed by disposing a heat source such as a halogen lamp inside a cored bar made of a hollow metal roller made of aluminum or the like. In the heating roller, the core metal is heated by the heat source. At this time, the power supply to the heat source is controlled to adjust the temperature so that the outer peripheral surface of the heating roller is maintained at a predetermined fixing temperature.

  The fixing device has the ability to sufficiently heat and melt a toner image composed of four toner layers (yellow, magenta, cyan and black) or five toner layers (yellow, magenta, cyan, black and clear) to mix colors. When used in an image forming apparatus that forms a required full-color image, it is preferable to have the following configuration. That is, the fixing device includes, as a heating roller, a core having a high heat capacity and an elastic layer for uniformly melting the toner image formed on the outer peripheral surface of the core. preferable.

  The pressure roller has an elastic layer made of a soft rubber such as urethane rubber or silicon rubber.

  As the pressure roller, a core metal made of a hollow metal roller made of aluminum or the like, and an elastic layer formed on the outer peripheral surface of the core metal may be used.

  Furthermore, when the pressure roller has a cored bar, a heat source such as a halogen lamp may be disposed inside the cored bar, like the heating roller. The core may be heated by the heat source, and the temperature may be adjusted by controlling energization of the heat source so that the outer peripheral surface of the pressure roller is maintained at a predetermined fixing temperature.

  As these heating rollers and / or pressure rollers, as the outermost layer, a mold release made of a fluororesin such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or the like is used. It is preferable to use a layer formed.

  In such a heat roller type fixing device, the roller pair is rotated and the image support to form a visible image is sandwiched and conveyed in the fixing nip portion, whereby the heating by the heating roller and the pressure in the fixing nip portion are reduced. Thus, an unfixed toner image is fixed on the image support.

  The image forming method of the present invention is characterized in that the low-temperature fixability is also good. Therefore, in the heat roller type fixing device, the temperature of the heating roller can be made relatively low, specifically 150 ° C. or less. Furthermore, the temperature of the heating roller is preferably 140 ° C. or lower, and more preferably 135 ° C. or lower. From the viewpoint of excellent low-temperature fixability, the temperature of the heating roller is preferably as low as possible, and the lower limit is not particularly limited, but is substantially about 90 ° C.

(Ii) Belt heating type fixing device Generally, a belt heating type fixing device is composed of, for example, a heating body made of a ceramic heater, a pressure roller, and a heat resistant belt between the heating body and the pressure roller. The fixing belt is sandwiched, and the pressure roller is deformed by the pressure applied between the heating body and the pressure roller, so that a so-called fixing nip is formed in the deformed portion. It is.

  As the fixing belt, heat-resistant belts and sheets made of polyimide or the like are used. The fixing belt has a heat-resistant belt and sheet made of polyimide or the like as a base, and a fluorine such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) on the base. It may have a configuration in which a release layer made of resin or the like is formed, and may further have a configuration in which an elastic layer made of rubber or the like is provided between the substrate and the release layer. .

  In such a belt heating type fixing device, an image support carrying an unfixed toner image is nipped and conveyed together with the fixing belt between a fixing belt forming a fixing nip portion and a pressure roller. Thus, heating by the heating body via the fixing belt and application of pressure at the fixing nip portion are performed, and the unfixed toner image is fixed on the image support.

  According to such a belt heating type fixing device, the heating body may be brought into a state in which the heating body is energized and heated to a predetermined fixing temperature only during image formation. Accordingly, it is possible to shorten the waiting time from when the power of the image forming apparatus is turned on to when the image forming apparatus can be executed. Further, the power consumption during standby of the image forming apparatus is extremely small, and there is an advantage that power saving can be achieved.

  As described above, the heating body, the pressure roller, and the fixing belt used as the fixing member in the fixing step preferably have a plurality of layer configurations.

  In the belt heating type fixing device, the temperature of the heating body can be relatively lowered, specifically, 150 ° C. or less. Furthermore, the temperature of the heating body is preferably 140 ° C. or lower, and more preferably 135 ° C. or lower. From the viewpoint of excellent low-temperature fixability, the temperature of the heating body is preferably as low as possible, and the lower limit is not particularly limited, but is substantially about 90 ° C.

(recoding media)
The recording medium (also referred to as recording material, recording paper, recording paper, etc.) may be a commonly used one, for example, as long as it holds a toner image formed by a known image forming method using an image forming apparatus or the like. It is not particularly limited. Examples of usable image supports include plain paper from thin paper to thick paper, high-quality paper, art paper, coated printing paper such as coated paper, commercially available Japanese paper and postcard paper, OHP Plastic films, fabrics, various resin materials used for so-called soft packaging, or resin films obtained by forming them into a film, labels, and the like.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said form, A various change can be added.

  The effects of the present invention will be described using the following examples and comparative examples. In the following examples, unless otherwise specified, “parts” and “%” mean “parts by mass” and “% by mass”, respectively, and each operation was performed at room temperature (25 ° C.). In addition, this invention is not limited to an Example below.

<Each analysis condition>
[Glass transition temperature of amorphous resin and melting point of crystalline resin]
The glass transition temperature (Tg) of the amorphous resin (styrene acrylic resin) was measured using “Diamond DSC” (manufactured by PerkinElmer). First, 3.0 mg of a measurement sample (resin) was sealed in an aluminum pan and set in a sample holder of “Diamond DSC”. The reference used an empty aluminum pan. Then, a first temperature raising process for raising the temperature from 0 ° C. to 200 ° C. at a temperature raising rate of 10 ° C./min, a cooling process for cooling from 200 ° C. to 0 ° C. at a cooling rate of 10 ° C./min, A DSC curve was obtained under the measurement conditions (temperature increase / cooling conditions) in which the second temperature increase process in which the temperature was increased from 0 ° C. to 200 ° C. per minute in this order. Based on the DSC curve obtained by this measurement, the maximum between the rising line of the first peak and the peak peak before the rising of the first endothermic peak in the second temperature rising process and the peak peak. A tangent line indicating an inclination is drawn, and the intersection is defined as a glass transition temperature (Tg).

  The melting point of the crystalline polyester resin is an endothermic peak derived from the crystalline resin in the second temperature raising process based on the DSC curve obtained in the same manner as described above (an endothermic peak having a half-value width of 15 ° C. or less). The temperature at the peak top of) was defined as the melting point (Tc).

[Weight average molecular weight and number average molecular weight of resin]
The molecular weight (weight average molecular weight and number average molecular weight) of each resin by GPC was measured as follows. That is, using an apparatus “HLC-8120GPC” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZ-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent at a flow rate. Flowed at 0.2 mL / min. The measurement sample (resin) was dissolved in tetrahydrofuran to a concentration of 1 mg / ml. The solution was prepared by performing treatment at room temperature for 5 minutes using an ultrasonic disperser. Next, a sample solution was obtained by processing with a membrane filter having a pore size of 0.2 μm, 10 μL of this sample solution was injected into the apparatus together with the carrier solvent, and detected using a refractive index detector (RI detector). The molecular weight distribution of the measurement sample was calculated based on a calibration curve created using monodisperse polystyrene standard particles. Ten polystyrenes were used for the calibration curve measurement.

<Preparation of each dispersion>
[Production Example 1: Preparation of crystalline polyester resin particle dispersion [dispersion c1]]
≪Synthesis of crystalline polyester resin [C1] ≫
A four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was charged with 0.8 parts by mass of Ti (n-OBu) ₄ as a raw material monomer of the following polycondensation resin and an esterification catalyst. The reaction was carried out at 4 ° C. for 4 hours.

・ 250 parts by mass of 1,12-dodecanediol ・ 250 parts by mass of decanedioic acid (sebacic acid) Thereafter, the temperature was raised to 210 ° C. at 10 ° C. per hour, and held at 210 ° C. for 5 hours, and then under reduced pressure (8 kPa) Crystalline polyester resin [C1] was obtained by reacting for 1 hour. The obtained crystalline polyester resin [C1] had a number average molecular weight (Mn) of 4,500 and a melting point of 81 ° C.

<< Preparation of crystalline polyester resin particle dispersion [dispersion c1] >>
30 parts by mass of the crystalline polyester resin [C1] was melted and transferred in the molten state to the emulsification disperser “Cabitron CD1010” (manufactured by Eurotech Co., Ltd.) at a transfer rate of 100 parts by mass. Simultaneously with the transfer of the crystalline polyester resin [C1] in the molten state, the emulsifier / disperser is charged with 0.37% by mass of dilute ammonia water (70 parts by mass of reagent ammonia water in the aqueous solvent tank is ion-exchanged). The product diluted with water was transferred at a transfer rate of 0.1 liter per minute while being heated to 100 ° C. with a heat exchanger. Then, this emulsifier / disperser is operated under the conditions of a rotor rotational speed of 60 Hz and a pressure of 5 kg / cm ² , and then ion-exchanged water is added to adjust the solid content to 20% by mass. A dispersion [dispersion c1] containing crystalline polyester resin particles having a standard median diameter of 200 nm was prepared. The volume-based median diameter (D50) was measured with a microtrack particle size distribution measuring device “UPA-150” (manufactured by Nikkiso Co., Ltd.) (hereinafter the same).

[Production Examples 2 to 9: Preparation of crystalline polyester resin particle dispersions [dispersion c2] to [dispersion c9]]
In the above-mentioned << Synthesis of crystalline polyester resin [C1] >>, the crystalline polyester resin [C2] is the same as described above except that the types and addition amounts of the raw material monomers used are changed as shown in Table 1 below. To [C9] were synthesized. Table 1 shows the number average molecular weight (Mn) and melting point of each crystalline polyester resin.

  Subsequently, in the above << Preparation of crystalline polyester resin particle dispersion [dispersion c1] >>, except that the crystalline polyester resin used was changed to crystalline polyester resins [C2] to [C9], respectively. Similarly, crystalline polyester resin particle dispersions [dispersion c2] to [dispersion c9] were prepared. The volume-based median diameter of the crystalline polyester resin particles contained in each of the dispersions was in the range of 100 to 400 nm.

[Production Example 10: Preparation of styrene acrylic resin particle dispersion [dispersion b1]]
In a 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction device, 5.0 parts by mass of sodium lauryl sulfate and 2500 parts by mass of ion-exchanged water are added and stirred at a stirring speed of 230 rpm under a nitrogen stream. The internal temperature was raised to 80 ° C.

  Subsequently, an aqueous solution in which 15.0 parts by mass of potassium persulfate (KPS) was dissolved in 300 parts by mass of ion-exchanged water was added, and the liquid temperature was again set to 80 ° C. Thereafter, a monomer mixed solution comprising 840.0 parts by mass of styrene (St), 288.0 parts by mass of n-butyl acrylate (BA), 72.0 parts by mass of methacrylic acid (MAA) and 15 parts by mass of n-octyl mercaptan. Was added dropwise over 2 hours. After completion of the dropping, polymerization was performed by heating and stirring at 80 ° C. for 2 hours to prepare [dispersion b1] of styrene acrylic resin [B1] particles having a volume-based median diameter of 120 nm.

  The glass transition temperature (Tg) of the styrene acrylic resin [B1] was 52.0 ° C., and the weight average molecular weight (Mw) was 28,000.

[Production Example 11: Preparation of release agent particle dispersion [W1]]
Paraffin wax (HNP0190, manufactured by Nippon Seiwa Co., Ltd. (melting point: 85 ° C.))
200 parts by mass ・ Sodium dodecyl sulfate 20 parts by mass ・ Ion-exchanged water 1800 parts by mass The above materials are mixed and heated to 95 ° C., and sufficiently dispersed in an IKA Ultra Turrax (registered trademark, hereinafter the same) T50 did. Thereafter, dispersion treatment was performed using a pressure discharge type gorin homogenizer to prepare a release agent particle dispersion [W1]. The volume-based median diameter of the release agent particles in this dispersion was 110 nm.

[Production Example 12: Preparation of black colorant particle dispersion [Bk]]
-Sodium dodecyl sulfate 90 parts by mass-Carbon black "Regal (registered trademark) 330R" (Cabot Corp.) 200 parts by mass-Ion-exchanged water 1600 parts by mass Ultra-Turrax T50 (IKA) After sufficiently dispersing in Step 1, a black colorant particle dispersion [Bk] was prepared by treating with an ultrasonic disperser for 20 minutes.

  With respect to the obtained black colorant particle dispersion [Bk], the volume-based median diameter of the colorant particles was 110 nm. The volume-based median diameter of the colorant particles was measured using a Microtrac particle size distribution analyzer “UPA-150” (manufactured by Nikkiso Co., Ltd.) (hereinafter the same).

[Production Example 13: Preparation of yellow colorant particle dispersion [Ye]]
-Sodium dodecyl sulfate 90 mass parts-C.I. I. Pigment Yellow 74 200 parts by mass-Ion-exchanged water 1600 parts by mass After sufficiently dispersing the solution in which the above components are mixed with Ultra Turrax T50 (manufactured by IKA), the mixture is treated with an ultrasonic disperser for 20 minutes to give yellow. A colorant particle dispersion [Ye] was prepared.

  With respect to the obtained yellow colorant particle dispersion [Ye], the volume-based median diameter of the colorant particles was 240 nm.

[Production Example 14: Preparation of magenta colorant particle dispersion [Ma]]
-Sodium dodecyl sulfate 90 mass parts-C.I. I. CI Pigment Red 269 200 parts by mass-Ion-exchanged water 1600 parts by mass After sufficiently dispersing the solution in which the above components are mixed with Ultra Turrax T50 (manufactured by IKA), the mixture is treated with an ultrasonic disperser for 20 minutes to obtain magenta. A colorant particle dispersion [Ma] was prepared.

  With respect to the obtained magenta colorant particle dispersion [Ma], the volume-based median diameter of the colorant particles was 200 nm.

[Production Example 15: Preparation of cyan colorant particle dispersion [Cy]]
-Sodium dodecyl sulfate 90 mass parts-C.I. I. Pigment Blue 15: 3 200 parts by mass ・ Ion-exchanged water 1600 parts by mass A solution in which the above components are mixed is sufficiently dispersed with an Ultra Turrax T50 (manufactured by IKA) and then treated with an ultrasonic disperser for 20 minutes. To prepare a cyan colorant particle dispersion [Cy].

  With respect to the obtained cyan colorant particle dispersion [Cy], the volume-based median diameter of the colorant particles was 180 nm.

<Manufacture of each toner (developer)>
[Production of Black Developer [BkD1]]
≪Aggregation / fusion process and aging process≫
In a reaction vessel equipped with a stirrer, a temperature sensor and a cooling tube, 38.4 parts by mass of crystalline polyester resin particle aqueous dispersion [dispersion c1] (7.7 parts by mass in terms of solid content), styrene acrylic resin particle dispersion [Dispersion b1] 268.8 parts by mass (solid content equivalent 80.6 parts by mass), Colorant particle dispersion [Bk] 51.9 parts by mass (solid content equivalent 5.8 parts by mass), Release agent particle dispersion After adding 76.8 parts by mass of liquid [W1] (7.7 parts by mass in terms of solid content), a 5 mol / liter sodium hydroxide aqueous solution was added to adjust the pH to 10.

  Next, an aqueous solution in which 12 parts by mass of magnesium chloride was dissolved in 12 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. The temperature was raised and the system was heated to 80 ° C. over 60 minutes. The particle size of the associated particles was measured with “Coulter Multisizer 3” (Beckman Coulter, Inc.). The stirring speed was controlled so as to be 6.0 μm. Thereafter, an aqueous solution in which 45 parts by mass of sodium chloride was dissolved in 180 parts by mass of ion-exchanged water was added to stop particle growth. Further, the particles were fused by heating and stirring at 80 ° C.

≪Cooling process≫
Thereafter, using an apparatus for measuring the average circularity of toner particles “FPIA-2100” (manufactured by Sysmex) (HPF detection number: 4000), when the average circularity reaches 0.957, cooling at 5 ° C./min. Cooled to 30 ° C. at a rate.

≪Filtering / washing process and drying process≫
Next, the operation of solid-liquid separation and re-dispersion of the dehydrated toner cake in ion-exchanged water and solid-liquid separation was repeated three times, followed by washing at 40 ° C. for 24 hours to obtain black toner particles [XBk1]. Obtained.

≪External additive addition process≫
To 100 parts by mass of the obtained toner particles [XBk1], 0.6 part by mass of hydrophobic silica (number average primary particle size = 12 nm, degree of hydrophobicity = 68) and hydrophobic titanium oxide (number average primary particle size = 20 nm, Hydrophobicity = 63) 1.0 part by mass was added, and after the external additive processing step of mixing with a “Henschel mixer” (manufactured by Mitsui Miike Chemical Co., Ltd.) for 20 minutes at a rotating blade peripheral speed of 35 m / sec and 32 ° C., By removing coarse particles using a sieve having an opening of 45 μm, black toner [Bk1] was obtained. The number average primary particle size of each of the external additives was determined by the method described in the section “External additive” above.

≪Developer production process≫
A ferrite carrier having a volume average particle diameter of 30 μm coated with a copolymer resin of cyclohexyl methacrylate and methyl methacrylate (monomer mass ratio = 1: 1) is used for the black toner [Bk1], and the toner concentration becomes 6% by mass. Thus, black developer [BkD1] was obtained by mixing.

[Production of Black Developer [BkD2] to [BkD10]]
In the above [Production of black developer [BkD1]], the same manner as above except that the type and amount of use (solid content) of the dispersion (resin) used were changed as shown in Table 2 below. Black developers [BkD2] to [BkD10] were produced.

[Production of Yellow Developer [YeD1] to [YeD10]]
In the above [Production of black developer [BkD1]], except that the type and amount of the dispersion (resin) used and the type and amount of the colorant were changed as shown in Table 3 below, respectively. In the same manner, yellow developers [YeD1] to [YeD10] were produced.

[Production of Magenta Developer [MaD1] to [MaD10]]
In the above [Production of black developer [BkD1]], except that the type and amount of the dispersion (resin) used and the type and amount of the colorant were changed as shown in Table 4 below, respectively. In the same manner as above, magenta developers [MaD1] to [MaD10] were produced.

[Production of Cyan Developers [CyD1] to [CyD10]]
In the above [Manufacture of black developer [BkD1]], except that the type and amount of the dispersion (resin) used and the type and amount of the colorant were changed as shown in Table 5 below, respectively. In the same manner, cyan developers [CyD1] to [CyD10] were produced.

[Production of Clear Developer [ClD1]]
Clear development in the same manner as above except that in the above [Production of black developer [BkD1]], the colorant was not used and the type of dispersion (resin) used was changed as shown in Table 6 below. An agent [ClD1] was produced.

<Evaluation>
Each evaluation was performed about the combination (developer set) shown in the following Table 7 using the developer manufactured above. The results are shown in Table 8. In Table 8, “content of crystalline polyester resin” indicates the content of crystalline polyester resin relative to the total mass of the crystalline polyester resin, amorphous resin (styrene acrylic resin), and release agent. Amount (mass%) is shown.

[Low temperature fixability]
The fixing device of the copying machine “bizhub PRESS (registered trademark) C1070” (manufactured by Konica Minolta Co., Ltd.) was modified so that the surface temperature (fixing temperature) of the heating roller could be changed in the range of 120 to 180 ° C. The copying machine was loaded with the developer in the combinations shown in Table 7 and evaluated.

First, in an environment of normal temperature and normal humidity (temperature 20 ° C., humidity 50% RH), black toner, yellow toner, magenta toner and cyan toner are placed on A4 size high-quality paper “CF paper” (manufactured by Konica Minolta Co., Ltd.). The adhesion amount of the superimposed images was set to 10.0 g / m ² (other than developer set 16). The developer set 16 was set so that the adhesion amount of an image obtained by superimposing black toner, yellow toner, magenta toner, cyan toner and clear toner was 12.5 g / m ² . At this time, setting was made so that there was no difference in the adhesion amount of black toner, yellow toner, magenta toner and cyan toner (and clear toner). Thereafter, a fixing experiment for fixing a four-color image of a size of 100 mm × 100 mm was repeatedly performed up to 180 ° C. while changing the fixing temperature to be increased in steps of 1 ° C. from 120 ° C.

  The printed matter at each fixing temperature obtained above was visually confirmed, and the lowest temperature at which all the toner did not adhere to the fixing device and fixed on the paper was defined as the minimum fixing temperature (° C.). The results are shown in Table 8 below. A sample having a minimum fixing temperature of 150 ° C. or lower is determined to be acceptable.

[Image density (Image density under high temperature and high humidity environment and low temperature and low humidity environment)]
Reproduce the copier "bizhub PRESS (registered trademark) C1070" (manufactured by Konica Minolta Co., Ltd.) and disable the control of temperature and humidity correction. Evaluation was performed.

First, in an environment of normal temperature and normal humidity (temperature 20 ° C., humidity 50% RH), the black image adhesion amount is 4.0 g / m ² on A4 size high-quality paper “CF paper” (manufactured by Konica Minolta Co., Ltd.). It set so that it might become. Similarly, the adhesion amount of an image obtained by superposing yellow toner, magenta toner, and cyan toner was set to 9.0 g / m ² (other than developer set 16). The developer set 16 was set so that the adhesion amount of an image obtained by superposing yellow toner, magenta toner, cyan toner and clear toner was 12.0 g / m ² . At this time, setting was made so that there was no difference in the adhesion amount of yellow toner, magenta toner and cyan toner (and clear toner).

  Thereafter, in a high temperature and high humidity (temperature 30 ° C., humidity 80% RH) and low temperature and low humidity (temperature 10 ° C., humidity 20% RH) environment, a black image of 100 mm × 100 mm size on A4 size high-quality paper “CF paper” And a superimposed image (3C image) of toner other than black toner was output.

  The transmission density was measured using a transmission densitometer “TD-904” (manufactured by Macbeth) for each of the black image and the 3C image obtained in a high temperature and high humidity environment and a low temperature and low humidity environment. The results are shown in Table 8 below. In each environment, the measured black image density and 3C image density of 0.90 or more are determined to be acceptable.

[Image density unevenness]
Reproduced copier "bizhub PRESS (registered trademark) C1070" (manufactured by Konica Minolta Co., Ltd.) and invalidated temperature / humidity correction control. Went.

First, in an environment of normal temperature and normal humidity (temperature 20 ° C., humidity 50% RH), black toner, yellow toner, magenta toner and cyan toner are placed on A4 size high-quality paper “CF paper” (manufactured by Konica Minolta Co., Ltd.). The adhesion amount of the superimposed images was set to 10.0 g / m ² (other than developer set 16). The developer set 16 was set so that the adhesion amount of an image obtained by superimposing black toner, yellow toner, magenta toner, cyan toner and clear toner was 12.5 g / m ² . At this time, setting was made so that there was no difference in the adhesion amount of black toner, yellow toner, magenta toner and cyan toner (and clear toner).

  Thereafter, the image density of 100 mm × 100 mm size on A4 size high quality paper “CF paper” in high temperature and high humidity (temperature 30 ° C., humidity 80% RH) and low temperature low humidity (temperature 10 ° C., humidity 20% RH) environment. A 60% halftone image was output.

  The image density of the obtained halftone image was measured at five points using a reflection densitometer “RD-918” (manufactured by Macbeth), and the reflection density difference (difference between the maximum value and the minimum value) of the halftone image was determined. The results are shown in Table 8 below. A reflection density difference of less than 0.10 is accepted.

[Comprehensive evaluation]
Table 8 shows the “comprehensive evaluation” based on the above evaluations in five stages. The criteria for the evaluation are shown below. In addition, in the following comprehensive evaluation, the larger the number, the better, and judging that 2 or more is acceptable;
≪Evaluation criteria≫
5: In the evaluation of the image density unevenness, the value with the larger reflection density difference among the results under the high temperature and high humidity environment or the low temperature and low humidity environment is 0.01 or less. 4: The value with the larger reflection density difference is 0. .01 and 0.04 or less 3: The value with the larger reflection density difference exceeds 0.04 and 0.07 or less 2: The value with the larger reflection density difference exceeds 0.07 and 0 Less than 10. 1: The value with the larger reflection density difference is 0.10 or more.

  From the results shown in Table 8 above, according to the toner (developer) sets (or image forming methods) of Examples 1 to 16, good low-temperature fixability was obtained. It was shown that the occurrence of density unevenness was suppressed even when the value of was changed. Therefore, according to the configuration of the present invention, it has been found that the environmental dependency of the image density unevenness is reduced while maintaining good low-temperature fixability.

  On the other hand, the toner (developer) sets (or image forming methods) of Comparative Examples 1 and 2 cause uneven density in the formed images depending on environmental changes, and maintain good low-temperature fixability. Further, it has not been possible to achieve both reduction in image density unevenness and environmental dependency.

Claims (9)

A black toner comprising carbon black, a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, an amorphous resin, and a release agent;
An image forming method using a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, an amorphous resin, and a toner other than the black toner, including a release agent. ,
The structural unit derived from the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the black toner is represented by A (B), and the crystalline polyester resin contained in the toner other than the black toner is constituted. An image forming method that satisfies the following formula (1), where A (C) is the carbon number of a structural unit derived from a linear aliphatic dicarboxylic acid.
The image forming method according to claim 1, further satisfying the following formula (2):
The image forming method according to claim 2, further satisfying the following expression (3):
The image forming method according to claim 1, further satisfying the following formula (4):
  Each of the black toner and the toner other than the black toner contains 6 to 15 of the crystalline polyester resin based on the total mass of the crystalline polyester resin, the amorphous resin, and the release agent. The image forming method according to claim 1, wherein the image forming method includes mass%.   The image forming method according to claim 1, wherein the amorphous resin contained in the black toner and the toner other than the black toner each contains a styrene acrylic resin.   The image forming method according to claim 1, wherein the toner other than the black toner is a colored toner.   The image forming method according to claim 7, wherein the toner other than the black toner is a yellow toner, a magenta toner, and a cyan toner. A black toner comprising carbon black, a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid, an amorphous resin, and a release agent;
An electrostatic latent image developing toner comprising: a crystalline polyester resin having a structural unit derived from a linear aliphatic dicarboxylic acid; an amorphous resin; and a toner other than the black toner. A set,
The structural unit derived from the linear aliphatic dicarboxylic acid constituting the crystalline polyester resin contained in the black toner is represented by A (B), and the crystalline polyester resin contained in the toner other than the black toner is constituted. An electrostatic latent image developing toner set that satisfies the following formula (1), where A (C) is the carbon number of a structural unit derived from a linear aliphatic dicarboxylic acid.