JP2007086222A - Electrophotographic toner, and electrophotographic developer and image forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic toner having excellent mechanical strength and heat resistance of a resultant image. <P>SOLUTION: There is provided the electrophotographic toner containing a polyester resin containing a biphenyl alkylene oxide structure expressed by general formula (1) and a colorant. In the formula, (n) denotes an integer of ≥2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, an electrophotographic developer using the toner, and an image forming method. is there.

Conventionally, in a color image forming apparatus for forming a color image by an electrophotographic method or an electrostatic recording method, a color image is formed on the surface of a recording medium. For example, when making a color copy, the following process is performed. An image is formed.
That is, the color original is illuminated, the reflected light image is color-separated and read by a color scanner, subjected to predetermined image processing and color correction by an image processing apparatus, and based on the obtained multiple-color image signals, for example, a semiconductor A laser or the like is modulated, and a laser beam modulated in accordance with an image signal is emitted from the semiconductor laser.

By irradiating the surface of an organic photoreceptor using an inorganic photoreceptor such as Se or amorphous silicon, or a phthalocyanine pigment, a bisazo pigment or the like as a charge generation layer, a plurality of electrostatic latent images with each laser beam. Form. A plurality of electrostatic latent images formed on the surface of the inorganic or organic photoreceptor are sequentially developed with four color toners such as yellow (Y), magenta (M), cyan (C), and black (K) each time. To do. Then, the developed toner image is transferred from an inorganic or organic photosensitive member to the surface of a recording medium such as paper, and is heat-fixed by a fixing device such as a heat fixing roll to form a color image on the surface of the recording medium.
The above-described electrophotographic system is exclusively used for copying, office printers and facsimiles, but has recently begun to be used for high-value-added printing applications such as photographic image printing and light printing.

By the way, the preference for the glossiness of a color image varies depending on the type and purpose of use of the image, and there are many kinds. High-gloss images tend to be preferred. In light printing applications, high gloss coated paper is often used, and high gloss equivalent to that of coated paper tends to be required.
It is known that the viscosity of a toner at the time of heat fixing changes and the glossiness of a color image changes depending on the type of binder resin used for the toner, the method of heat fixing, and the like.
As a technique for obtaining a high gloss image in a color image forming apparatus, it is known that a high gloss image can be obtained by using a color copying machine and selecting a toner material, fixing conditions and the like ( For example, see Patent Documents 1 to 3).

Further, a toner image is formed on a recording medium provided with a toner receiving layer, or a recording medium on which a toner image and a transparent toner image are formed is heated and melted using a belt-type fixing device, and then cooled and peeled off. An apparatus for forming a high gloss image such as a silver salt photograph (see Patent Document 4) is also known.
However, in the case of the techniques described in Patent Documents 1 to 3, since the unevenness of the toner remains on the image surface and does not become smooth like silver salt photography or printing, there is also a problem that a smooth texture cannot be obtained. Have. In order to make the toner flow as smooth as possible, the fixing process must be performed at a higher temperature and a higher pressure for a longer time in order to make the toner flow more.
In addition, when using the apparatus described in Patent Document 4, in order to embed toner in the toner receiving layer, or to fix an umbrella-like transparent toner image in addition to the toner image, the fixing process is performed at a high temperature and high pressure for a long time. It must be time.

  Further, when the speed of the recording medium passing through the fixing device is high, a step is conspicuous at the boundary between the high density portion and the low density portion, and the low density small spot in the high density portion seems to have a hole. Have the problem of being dented. This is because the toner necessary for embedding the toner in the toner receiving layer or the binder resin in the transparent toner does not sufficiently flow to fill the step of the toner image.

In addition to the above reasons, thick coated paper is often used as a recording medium in photographic image printing and light printing applications, and it can be said that the amount of heat taken away by the recording medium in the fixing process is large.
Since the energy required for fixing is large, as long as the temperature and pressure conditions of the fixing device are used within a practical range, the technique described in the above document can obtain a uniform image with high printing speed and high gloss. There is a problem that it is impossible to achieve both.
Considering the reduction of energy consumption in image formation to solve this problem, a toner that can be fixed at a low temperature is required. In order to satisfy such low-temperature fixability, reducing the molecular weight of the binder resin used in the toner and lowering the glass transition point are effective solutions.

However, the electrophotographic toner used in the above technique has a heat resistance problem that an image fixed by high temperature and high humidity environment or long-term storage is deformed or offset.
Blocking (when stored in a car or warehouse in summer or left in a high-temperature environment such as transporting at the bottom of a ship, with the image surface and back, image surfaces overlapping, and the image surface and album material, etc.) There is a concern that a problem may occur that the surface cannot be peeled off or the surface is damaged even if it is peeled off. In this case, increasing the glass transition point of the binder resin and increasing the molecular weight are effective for improving the heat resistance at high temperatures.
Furthermore, an improvement in durability when the image is bent, that is, improvement in mechanical strength is also an important issue. In order to increase the mechanical strength, increasing the molecular weight of the binder resin is an effective solution.
Thus, the improvement in mechanical strength and heat resistance is contrary to the improvement in low-temperature fixability. In particular, when making high gloss images for applications such as photographic image printing and light printing, it is necessary to increase the fixing temperature. Therefore, satisfying all three characteristics of mechanical strength, heat resistance and low temperature fixing property It becomes difficult.

Regarding the mechanical strength, conventional toners using an amorphous resin have a problem that the mechanical strength against bending is low and cracking is likely to occur.
In recent years, there has been a demand for a binder resin for toner having excellent low-temperature fixability and good storage stability, and crystalline polyester has been used to meet such needs, or crystalline polyester and amorphous resin. It has been proposed to use polyester together (see Patent Documents 5 to 6).
These technologies are effective in achieving both low-temperature fixability and heat resistance durability against offset and blocking, but in the long run, embrittlement and gloss fluctuations occur due to slow crystallization. There is a problem of end. In the case of a transparent toner using a crystalline resin, even if the image after fixing is supple, if time passes and crystallization progresses, peeling tends to occur at the crystal interface. More cracks are likely to occur.

When high-value-added printing applications such as electrophotographic photographic image printing and light printing are assumed, uniform cracks generated on the glossy surface are very conspicuous, and the value of printing is greatly impaired. In particular, a color image having a high toner volume formed on thick paper has a large stress when a bending mechanical force is applied, and therefore, a crack is generated by a slight external force.
If photographic image printing and light printing by electrophotography require the same quality as existing silver salt photography and offset printing, improvement of the cracks in the toner image that forms the image is one of the most serious issues. I can say that.
JP-A-5-142963 JP-A-3-2765 JP-A 63-259575 JP-A-5-158364 JP 2001-222138 A JP 11-249339 A

  An object of the present invention is to solve the above problems. That is, an object of the present invention is to provide an electrophotographic toner excellent in mechanical strength and heat resistance of an image obtained, an electrophotographic developer using the toner, and an image forming method.

〔一般式（１）中、ｎは２以上の整数を表す。〕 The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1>
An electrophotographic toner comprising a polyester resin containing a biphenylalkylene oxide structure represented by the following general formula (1) and a colorant.

[In General Formula (1), n represents an integer of 2 or more. ]

<2>
<1> The electrophotographic toner according to <1>, wherein the polyester resin containing a biphenylalkylene oxide structure has a melting point and a glass transition point and satisfies the following formula (1).
・ Formula (1)
0.02 ≦ S (Tm) / {S (Tm) + S (Tg)} ≦ 0.3
[In the formula (1), S (Tm) represents the area of the endothermic peak resulting from the melting point when the polyester resin containing the biphenylalkylene oxide structure is measured with a differential scanning calorimeter, and S (Tg) is the biphenyl. It represents the area of the endothermic peak due to the glass transition point when a polyester resin containing an alkylene oxide structure is measured with a differential scanning calorimeter. ]

〔一般式（２）中、ｎは２以上の整数を表す。〕 <3>
The polyester resin containing the biphenylalkylene oxide structure is prepared by polymerizing a carboxylic acid component and an alcohol component, and 2 to 70 mol% of all alcohol components used for the polymerization is represented by the following general formula (2). The electrophotographic toner according to <1> or <2>, which is a diol having a biphenylalkylene oxide structure represented.

[In General Formula (2), n represents an integer of 2 or more. ]

<4>
<2> The electrophotographic toner according to <3>, wherein 2 to 70 mol% of all alcohol components used in the polymerization is a diol containing the biphenylalkylene oxide structure.

<5>
<3> or <4>, wherein the alcohol component includes a diol containing a biphenylalkylene oxide structure represented by the general formula (2) and a linear aliphatic diol having 6 to 12 carbon atoms. The toner for electrophotography described.

<6>
Aggregation for forming aggregated particles in a raw material dispersion containing a resin particle dispersion in which resin particles containing a polyester resin containing a biphenylalkylene oxide structure are dispersed and a colorant dispersion in which the colorant is dispersed Process,
The electrophotographic toner according to any one of <1> to <5>, wherein the toner is produced through at least a fusing step of fusing the aggregated particles by heating.

<7>
The toner for electrophotography according to any one of <1> to <6>, wherein the volume average particle diameter is in a range of 2 to 12 μm.

<8>
The toner for electrophotography according to any one of <1> to <7>, wherein the volume average particle diameter is in a range of 3 to 9 μm.

<9>
The toner for electrophotography according to any one of <1> to <8>, wherein a shape factor defined by the following formula (2) is within a range of 115 to 140.
・ Formula (2)
Shape factor = [(absolute maximum length of toner particles) ² ] / [(projected area of toner particles) × π × (1/4) × 100]

<10>
The toner for electrophotography according to any one of <1> to <9>, wherein the toner contains a crystalline resin in a range of 5 to 90% by weight.

<11>
The electrophotographic toner according to any one of <1> to <10>, wherein the melting point is in a range of 50 ° C to 120 ° C.

<12>
An electrophotographic developer comprising the electrophotographic toner according to any one of <1> to <11>.

<13>
A latent image forming step for forming an electrostatic latent image on the surface of the latent image holding member and a developer carried on the developer carrying member are used to develop the electrostatic latent image formed on the surface of the latent image holding member. A developing step for forming a toner image, a transfer step for transferring the toner image formed on the surface of the latent image carrier to the surface of the recording medium, and a fixing step for thermally fixing the toner image transferred to the surface of the recording medium. In an image forming method including:
The image forming method, wherein the developer is the electrophotographic developer according to <12>.

  As described above, according to the present invention, it is possible to provide an electrophotographic toner excellent in mechanical strength and heat resistance of an obtained image, an electrophotographic developer using the toner, and an image forming method. .

<Toner for electrophotography>
An electrophotographic toner of the present invention (hereinafter sometimes abbreviated as “toner”) includes a polyester resin having a biphenylalkylene oxide structure represented by the following general formula (1) and a colorant. .

  Here, in General formula (1), n represents an integer greater than or equal to 2, and the inside of the range of 2-6 is preferable.

The polyester resin used in the toner of the present invention contains a biphenylalkylene oxide structure.
Here, since the biphenyl structure interacts with the benzene ring constituting the biphenyl structure of the adjacent polyester resin molecule, the interaction between molecules is also strengthened as a result. Therefore, the mechanical strength of an image formed using the toner of the present invention can be increased.
In addition, when the benzene ring contained in the repeating unit does not form a biphenyl structure, that is, when only one benzene ring is contained or when two or more benzene rings are contained, the benzene ring is formed as in the biphenyl structure. When the constituent carbon atoms are not directly bonded, the interaction between the benzene rings contained in the adjacent polyester resin molecules occurs, but the interaction is insufficient compared to the biphenyl structure. You cannot get strength.

  On the other hand, the biphenyl structure itself has high rigidity, and if the repeating unit is mainly composed of the biphenyl structure, the degree of amorphization of the resin is small and the heat resistance of the image cannot be ensured. However, in the present invention, since an alkylene oxide structure having a high degree of freedom of movement of the molecular chain is provided on both sides of the biphenyl structure, such a problem can be avoided.

In addition, it is more preferable that the polyester resin containing the biphenylalkylene oxide structure represented by the general formula (1) has a melting point and a glass transition point and satisfies the following formula (1).
・ Formula (1)
0.02 ≦ S (Tm) / {S (Tm) + S (Tg)} ≦ 0.3
Here, in formula (1), S (Tm) represents the area of the endothermic peak due to the melting point when the polyester resin containing the biphenylalkylene oxide structure is measured with a differential scanning calorimeter, and S (Tg) is The area of the endothermic peak resulting from the glass transition point when the polyester resin containing the biphenylalkylene oxide structure is measured with a differential scanning calorimeter is represented.
When S (Tm) / {S (Tm) + S (Tg)} exceeds 0.3, the adhesion of the obtained image to the recording medium may be reduced, and the image may be easily peeled off. When S (Tm) / {S (Tm) + S (Tg)} is less than 0.02, the heat resistance of the image may be insufficient.
From such a viewpoint, S (Tm) / {S (Tm) + S (Tg)} is more preferably in the range of 0.02 to 0.04.

In the present invention, the melting point Tm and the glass transition point Tg of the binder resin such as the polyester resin described above conform to JIS K 7121: 87 (plastic transition temperature measuring method), and a differential scanning calorimeter (Shimadzu Corporation). Using DSC-60), 10 mg of resin was measured from room temperature to 200 ° C. at a rate of temperature increase of 10 ° C. per minute with the same weight of alumina as a reference.
Further, endothermic peak areas S (Tm) and S (Tg) were determined based on a graph showing endothermic / exothermic changes with respect to temperature obtained when measuring Tm and Tg. FIG. 1 is a diagram for explaining endothermic peak areas S (Tm) and S (Tg) measured by a differential scanning calorimeter. In the figure, the horizontal axis represents temperature, and the vertical axis represents changes in calorie. This curve represents the change in calorific value with respect to the temperature measured by a differential scanning calorimeter. Here, the regions surrounded by the curve portions forming the endothermic peaks caused by Tm and Tg and the baseline having almost no change in the amount of heat with respect to the temperature were defined as the endothermic peak areas S (Tm) and S (Tg), respectively.

Next, materials and physical property values constituting the toner of the present invention will be described in detail below.
The toner of the present invention contains a binder resin and a colorant. As the binder resin, a polyester resin containing a biphenylalkylene oxide structure represented by the general formula (1) is always used. Moreover, other components, such as a mold release agent, may be contained as needed.

<Binder resin>
The binder resin used in the toner of the present invention includes a polyester resin containing a biphenylalkylene oxide structure represented by the general formula (1) as a main component, and includes a biphenylalkylene oxide structure occupying in all binder resin components. The proportion of the polyester resin is preferably 70% by weight or more, more preferably 80% by weight or more, further preferably 90% by weight or more, and all the binder resins contain a biphenylalkylene oxide structure. It is preferable to consist of resin.
Also, a polyester resin containing a biphenylalkylene oxide structure is used in combination with a polyester resin not containing a biphenylalkylene oxide structure, and other known binder resins such as a styrene / acrylic copolymer and a styrene / butadiene copolymer. May be.

Here, the polyester resin containing a biphenylalkylene oxide structure is particularly preferably a crystalline resin. In this case, it is preferable to use an amorphous polyester resin as the other resin used in combination. Moreover, you may use together the crystalline polyester resin which does not contain a biphenyl alkylene oxide structure as needed.
However, in the present invention, “crystallinity” of “crystalline resin” means that an endothermic peak due to the melting point is observed in differential scanning calorimetry (DSC), and this endothermic peak is a stepwise endothermic change. It means having a clear endothermic peak.
The polyester resin that contains / does not contain a biphenylalkylene oxide structure and is used in the toner of the present invention regardless of crystallinity / amorphity is a polymer in which other components are copolymerized with the polyester resin main chain. However, in the present invention, a copolymer in which the proportion of the other component (third component) in the main chain is 50 mol% or less is referred to as a polyester resin, and the melting point is adjusted as necessary. An appropriate third component may be copolymerized. The copolymerization ratio of these other components is preferably 12.5 mol% or less, more preferably 2 mol% or less.

(Polyester resin containing biphenylalkylene oxide structure)
The polyester resin containing a biphenylalkylene oxide structure is synthesized by polymerizing a carboxylic acid component and an alcohol component in the same manner as a conventional polyester resin, and at least one of the monomers is represented by the general formula (1). Those having a unit structure (excluding the ester bond portion) shown in FIG.
As the monomer containing a biphenylalkylene oxide structure, for example, it is preferable to use a diol containing a biphenylalkylene oxide structure as shown by the following general formula (2) from the viewpoint of easy availability of the material. It is not something. In the following general formula (2), n is an integer of 2 or more. In addition, in the following description, it demonstrates on the assumption that it superposes | polymerizes using the diol containing a biphenyl alkylene oxide structure as shown by General formula (2).

In this case, it is preferable that the ratio of the diol containing the biphenylalkylene oxide structure represented by the general formula (2) is 2 to 70 mol%, and 30 to 70 mol% among all alcohol components used in the polymerization. Is more preferable.
When the ratio of the diol containing the biphenylalkylene oxide structure represented by the general formula (2) in the total alcohol component is less than 2 mol%, the mechanical strength and heat resistance of the obtained image may not be sufficiently obtained. is there. On the other hand, if it exceeds 70 mol%, the melting point and melt viscosity of the resulting resin will be high, and there may be a problem in fixability when used as a toner.

  Of all the alcohol components, alcohol components other than the diol containing the biphenylalkylene oxide structure represented by the general formula (2) can be used as alcohol components used for polymerization of general polyester resins. From the viewpoint of enhancing the properties, it is preferable to use a linear aliphatic diol having 2 to 12 carbon atoms.

Specific examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, Examples include, but are not limited to, 1,18-octadecanediol, 1,20-eicosanediol, and the like.
From the viewpoints of fixability and heat resistance, a linear aliphatic diol having 6 to 12 carbon atoms is preferable, and nonanediol having 9 carbon atoms is more preferable.

On the other hand, examples of the carboxylic acid component include aromatic and aliphatic dicarboxylic acids. Aromatic dicarboxylic acids are preferred from the viewpoints of miscibility, mechanical strength, and heat resistance.
Examples of the aromatic dicarboxylic acid include terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, and the like. Among them, terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, and 2,6-naphthalenedicarboxylic acid are preferable in terms of mechanical strength, and from the viewpoint of maintaining good miscibility, The aromatic component is preferably in the range of 90 mol% or more.
Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, Or lower alkyl esters and acid anhydrides thereof, but are not limited thereto.

In addition, from the viewpoint of chargeability and transparency, bisphenol A, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, hydrogenated bisphenol A, bisphenol S, bisphenol S ethylene oxide adduct, and bisphenol S are used as necessary. It is preferable to use a diol component such as a propylene oxide adduct. Furthermore, it is particularly preferable to use bisphenol S derivatives such as bisphenol S, bisphenol S ethylene oxide adduct, and bisphenol S propylene oxide adduct from the viewpoint of toner manufacturability, heat resistance, and transparency.
From the viewpoint of heat resistance, the third component derived from alcohol is preferably in the range of 2 to 15 mol%, more preferably in the range of 3 to 8 mol%, with respect to all alcohol components.

There is no restriction | limiting in particular as a manufacturing method of the polyester resin containing a biphenyl alkylene oxide structure, It can manufacture by the general polyester polymerization method which makes a carboxylic acid component and an alcohol component react like a normal polyester resin.
That is, an oligomer can be obtained by esterifying or transesterifying a dibasic acid and a dihydric alcohol, and then synthesized by performing a polycondensation reaction under vacuum. Further, it can also be obtained by a polyester depolymerization method as described in JP-B-53-37920, for example. In addition, as a dibasic acid, a transesterification reaction is performed using at least one alkyl ester of a dicarboxylic acid such as dimethyl terephthalate, and then a polycondensation reaction is performed. A condensation reaction may be performed.
For example, a dibasic acid and a dihydric alcohol are reacted at 180 to 200 ° C. under atmospheric pressure for 2 to 5 hours, and the distillation of water or alcohol is terminated to complete the transesterification reaction. Next, the pressure in the reaction system is set to a high vacuum of 1 mmHg or less, and the temperature is raised to 200 to 230 ° C. and heated at this temperature for 1 to 3 hours to obtain a polyester resin containing a biphenylalkylene oxide structure.

The crystallinity / non-crystallinity and the degree of crystallinity of the polyester resin containing the biphenylalkylene oxide structure can be easily controlled by adjusting the type and ratio of the monomer used for the polymerization. It is particularly preferred that the polyester resin containing a biphenylalkylene oxide structure is a crystalline resin.
In the following description, the polyester resin containing a biphenylalkylene oxide structure will be described on the assumption that it is at least a crystalline resin. However, of course, the present invention is not limited to this. In addition to the crystalline polyester resin containing a biphenylalkylene oxide structure, An amorphous polyester resin containing a biphenylalkylene oxide structure can also be used in combination.
Moreover, if the diol and dicarboxylic acid which do not contain a biphenylalkylene oxide structure as shown by the general formula (1) are used, a conventional crystalline polyester resin which does not contain a biphenylalkylene oxide structure can be easily obtained. .

(Amorphous polyester resin)
The polyester resin containing a biphenylalkylene oxide structure used in the present invention is particularly preferably a crystalline resin. In this case, it is preferable to use a combination of amorphous polyester resins.
The glass transition point of the amorphous polyester resin used is preferably in the range of 50 to 80 ° C, more preferably in the range of 55 to 65 ° C. The weight average molecular weight is preferably in the range of 8000 to 30000, but from the viewpoint of mechanical strength, the weight average molecular weight is more preferably in the range of 8000 to 16000. Then, from the viewpoint of mixing properties, the third component may be copolymerized.
The amorphous polyester resin preferably has a common alcohol component or carboxylic acid component with the crystalline polyester resin used in combination with the amorphous polyester resin in order to increase the miscibility.
In particular, when the main component of the alcohol component of the crystalline polyester resin is a linear aliphatic component and the main component of the carboxylic acid component is an aromatic component, the same linear aliphatic alcohol component is 10% of the total diol. Included in the range of -30 mol%, and by containing 90 mol% or more of the same carboxylic acid component aromatic component with respect to all carboxylic acid components, miscibility is enhanced, melt mixing can be performed at low temperature, and heat resistance is good Can be obtained.

Furthermore, when an aromatic component that is an alcohol component is included as the third component of the crystalline polyester resin, the same aromatic component is used as the main component of the alcohol component of the amorphous polyester resin, and this aromatic component is added to all alcohol components. It is particularly preferable from the viewpoint of miscibility and heat resistance that the group component is contained in the range of 70 to 90 mol%.
The method for producing an amorphous polyester resin is not particularly limited, as with the method for producing a polyester resin containing a biphenylalkylene oxide structure described above, and can be produced by a general polyester polymerization method as described above.

  As the carboxylic acid component, various dicarboxylic acids mentioned for the crystalline polyester can be used similarly. As the alcohol component, various diols can be used. In addition to the aliphatic diols mentioned for the crystalline polyester, bisphenol A, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct and hydrogenated bisphenol A are used. Bisphenol S, bisphenol S ethylene oxide adduct, bisphenol S propylene oxide adduct, and the like can be used. Furthermore, it is particularly preferable to use bisphenol S derivatives such as bisphenol S, bisphenol S ethylene oxide adduct, and bisphenol S propylene oxide adduct from the viewpoints of toner manufacturability, heat resistance, and transparency. In the case of an amorphous polyester resin, both the carboxylic acid component and the alcohol component may contain a plurality of components. In particular, bisphenol S has an effect of improving heat resistance when it is amorphous. Depending on the composition of the amorphous resin, another third component such as a bisphenol A derivative is preferably used in combination.

-Molecular weight and acid value of polyester resin-
The toner of the present invention can be produced using a known dry method or wet method, but when produced using an emulsion polymerization aggregation method described later, the binder resin used for the production of the toner is emulsified. It is preferable to have physical properties suitable for the formation of a product.
Here, the molecular weight and acid value of the crystalline or amorphous polyester resin containing a biphenylalkylene oxide structure used in the production of the toner, or other crystalline polyester resin or amorphous polyester resin satisfy the following conditions. This is true.

That is, the weight average molecular weight of the crystalline polyester resin is preferably 16000-40000. Further, when the number average molecular weight Mn (c) of the crystalline polyester resin and the acid value are AV (c), it is preferable to satisfy the following formula (2).
・ Formula (2)
1.12 × 10 ⁴ /Mn(c)<AV(c)<2.25×10 ⁵ / Mn (c)

The weight average molecular weight of the amorphous polyester resin is preferably 8000 to 26000. Further, when the number average molecular weight Mn (a) of the amorphous polyester resin and the acid value are AV (a), it is preferable to satisfy the following formula (3).
・ Formula (3)
5.61 × 10 ⁴ /Mn(a)<AV(a)<2.25×10 ⁵ / Mn (a)

However, depending on the synthesis conditions and molecular weight, an acid value imparting treatment after resin synthesis, such as adding a polyvalent acid to the end of the resin molecular chain, may be required to achieve the above conditions.
Therefore, in view of manufacturability, it can be said that an unnecessary condition for the acid value imparting treatment is desirable. As conditions for obtaining an emulsion having a preferable shape without requiring an acid value treatment, the weight average molecular weight of the crystalline polyester resin is 16000 to 28000, and the weight average molecular weight of the amorphous polyester resin is 8000 to 20000. preferable.
In addition to this, the relationship between the number average molecular weight Mn (c) of the crystalline polyester resin and the acid value AV (c), and the number average molecular weight Mn (a) of the amorphous polyester resin and the acid value AV ( The relationship with a) preferably satisfies the following formula (4) and the following formula (5).
・ Formula (4)
8.96 × 10 ⁴ /Mn(c)<AV(c)<1.34×10 ⁵ / Mn (c)
・ Formula (5)
8.96 × 10 ⁴ /Mn(a)<AV(a)<1.34×10 ⁵ / Mn (a)
By synthesizing the resin so that the acid monomer comes to the end of the molecular chain so as to satisfy such a condition, it becomes easy to obtain an emulsion having a preferable shape without requiring an acid value imparting treatment after the resin synthesis.

If the above molecular weight and acid value conditions are satisfied, both the crystalline polyester resin and the amorphous polyester resin have hydrophilicity suitable for emulsification, the particle size is submicron, and the particle size is uniform. Thus, preferable resin particles suitable for the production of the toner can be obtained. When the emulsion in this mode is used, the transparency when used as a toner is improved, and the flexibility of the resin is increased to improve the mechanical strength.
It is possible to agglomerate and fuse even when the resin particles are large, but the toner prepared in this way has poor transparency because the crystal component is dispersed in a large size, and the sharpness of the image when a color image is laminated. May be damaged. Further, if the crystalline component and the amorphous component are separated, peeling is likely to occur at the interface, which may result in a brittle resin that is easily cracked.

  Further, when the toner of the present invention uses two or more types of binder resins, a method of dissolving the plurality of resins in a solvent and suspending them in an aqueous layer and then removing the solvent without satisfying the above conditions However, although an equivalent emulsion can be obtained, it can be said that emulsification is preferably carried out in an aqueous layer from the viewpoint of manufacturability and environmental burden. Also, considering the stability of the resin particles obtained by emulsification and the aggregation particles obtained by aggregating particles of other components, the raw material resin itself is given hydrophilicity enough to be emulsified in an aqueous layer. Preferably it is. Moreover, it is preferable that both resin particles have sufficient stability in an aqueous layer for mixing by aggregation of the crystalline resin / amorphous resin emulsion.

-Mixing ratio, ratio of crystalline resin-
When the toner of the present invention is used by mixing a crystalline resin and an amorphous resin as a binder resin, the ratio of the crystalline resin in the binder resin is considered in consideration of heat resistance, mechanical strength, and miscibility. It is preferably at least 10% by weight or more.
When the toner of the present invention is produced using an emulsion polymerization aggregation method, a crystalline resin, an amorphous resin and an emulsion may be mixed and used, or the crystalline resin emulsion may be mixed with other emulsions. The particles may be aggregated together with the components to form aggregated particles, and the aggregated particles may be covered with an amorphous resin emulsion.
The proportion of the crystalline resin contained in the toner particles is preferably in the range of 5 to 90% by weight. When the proportion of the crystalline resin contained in the toner particles is less than 5% by weight, the low-temperature fixability may be insufficient, and when it exceeds 90% by weight, there may be a problem with the chargeability. In addition, since the fixed image does not gloss, it may be undesirable in terms of image quality.

<Colorant>
There is no restriction | limiting in particular as a coloring agent used for the toner of this invention, A well-known coloring agent is mentioned, According to the objective, it can select suitably. One type of pigment may be used alone, or two or more types of pigments of the same type may be mixed and used. Two or more different types of pigments may be mixed and used.
Examples of the black pigment include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, and magnetite.
Examples of yellow pigments include yellow lead, zinc yellow, yellow iron oxide, cadmium yellow, chrome yellow, hansa yellow, hansa yellow 10G, benzidine yellow G, benzidine yellow GR, selenium yellow, quinoline yellow, permanent yellow NCG, and the like. be able to.

  Examples of the orange pigment include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, benzidine orange G, indanthrene brilliant orange RK, and indanthrene brilliant orange GK.

  Red pigments include Bengala, cadmium red, red lead, mercury sulfide, watch young red, permanent red 4R, risor red, brilliantamine 3B, brilliantamine 6B, dapon oil red, pyrazolone red, rhodamine B rake, lake red C Naphthol red such as Rose Bengal, Eoxin Red, Alizarin Lake, Pigment Red 146, 147, 184, 185, 155, 238 and 269.

  Blue pigments include bitumen, cobalt blue, alkali blue rake, Victoria blue rake, fast sky blue, indanthrene blue BC, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxare. Rate.

Examples of purple pigments include manganese purple, fast violet B, and methyl violet lake.
Examples of the green pigment include chromium oxide, chromium green, pigment green, malachite green lake, final yellow green G, and the like.
Examples of white pigments include zinc white, titanium oxide, antimony white, and zinc sulfide.

Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white.
Examples of the dye include various dyes such as basic, acidic, dispersed, direct, oil-soluble dyes, such as nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue, and acridine, xanthene, azo Benzoquinone, azine, anthraquinone, dioxazine, thiazine, azomethine, indigo, thioindigo, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazole, xanthene, etc. Various dyes can be used.
In addition, you may mix black pigments, such as carbon black, and dye to such an extent that transparency is not reduced to these colorants.

The content of the colorant in the toner of the present invention is preferably from 1 to 30 parts by weight with respect to 100 parts by weight of the binder resin. Of these, the larger number is preferable. Increasing the content of the colorant is advantageous in that the thickness of the image can be reduced when an image having the same density is obtained, which is effective in preventing offset.
In addition, by appropriately selecting the type of the colorant, each color toner such as yellow toner, magenta toner, cyan toner, and black toner can be obtained.

<Other ingredients>
In the toner of the present invention, in addition to the above essential components, other components that can be used in conventionally known general toners can be appropriately used. There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, well-known various additives, such as inorganic fine particles, organic fine particles, a charge control agent, a mold release agent, etc. are mentioned.
The inorganic fine particles are generally used for the purpose of improving toner fluidity. Examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, cerium chloride. , Bengara, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, zirconium oxide, silicon carbide, silicon nitride and the like. Among these, silica fine particles are preferable, and silica fine particles that have been hydrophobized are particularly preferable.

The average primary particle size (number average particle size) of the inorganic fine particles is preferably 1 to 1000 nm, and the addition amount (external addition) is 0.01 to 20 parts by weight with respect to 100 parts by weight of the toner. preferable.
The organic fine particles are generally used for the purpose of improving cleaning properties and transferability. Examples of the organic fine particles include fine particles such as polystyrene, polymethyl methacrylate, and polyvinylidene fluoride.
The charge control agent is generally used for the purpose of improving chargeability. Examples of the charge control agent include salicylic acid metal salts, metal-containing azo compounds, nigrosine and quaternary ammonium salts.

  The release agent is generally used for the purpose of improving release properties. Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide Plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc. Mineral / petroleum waxes; ester waxes such as fatty acid esters, montanic acid esters, and carboxylic acid esters. In this invention, these mold release agents may be used individually by 1 type, and may use 2 or more types together.

The addition amount of these release agents is preferably 0.5 to 50% by weight, more preferably 1 to 30% by weight, and further preferably 5 to 15% by weight with respect to the total amount of toner. If the amount is less than 0.5% by weight, the effect of adding the release agent may be insufficient. If the amount is 50% by weight or more, the chargeability is likely to be affected, or the toner is easily destroyed inside the developing machine. As a result, the release agent becomes spent on the carrier and the charge tends to be lowered, and the bleeding on the image surface during fixing tends to be insufficient. Since the agent tends to stay, transparency may deteriorate.
When the toner is prepared by an emulsion polymerization aggregation method, these components are dispersed by dispersing the above-described other components together with a dispersion containing an emulsion of a binder resin or a dispersion containing a colorant. By mixing and aggregating the liquid, the toner can be internally added.

The surface of the toner of the present invention may be covered with a surface layer. It is desirable that the surface layer does not greatly affect the mechanical properties and melt viscoelastic properties of the entire toner.
Therefore, it is desirable that the thickness of the surface layer is thin, and specifically, it is preferable to be in the range of 0.001 to 0.5 μm.
In order to form a thin surface layer in the above range, a method of chemically treating the surface of particles containing binder resin, colorant, inorganic fine particles added as necessary, and other materials is suitable. used.
Examples of the component constituting the surface layer include silane coupling agents, isocyanates, or vinyl monomers, and the component preferably has a polar group introduced therein and is chemically bonded. As a result, the adhesive force between the toner and the recording medium such as paper increases.

The polar group may be any polar functional group such as carboxyl group, carbonyl group, epoxy group, ether group, hydroxyl group, amino group, imino group, cyano group, amide group, imide group. , Ester groups, sulfone groups and the like.
Examples of the chemical treatment method include a strong oxidizing substance such as peroxide, a method of oxidizing by ozone oxidation, plasma oxidation, and the like, a method of bonding a polymerizable monomer containing a polar group by graft polymerization, and the like. By the chemical treatment, the polar group is firmly bonded to the molecular chain of the crystalline resin through a covalent bond.
In the present invention, a chargeable substance may be chemically or physically attached to the toner particle surface. Further, fine particles such as metal, metal oxide, metal salt, ceramic, resin, and carbon black may be externally added for the purpose of improving charging property, conductivity, powder fluidity, lubricity and the like. These external additives have an average particle diameter of about 5 to 100 nm, and include, for example, inorganic fine particles such as silicon oxide, titanium oxide, and aluminum oxide, and / or polymethyl methacrylate (PMMA), polyvinyl difluoride (PVDF). ) And the like can be used.

-Toner production method-
The toner of the present invention can be produced using a known toner production method such as a dry method such as a kneading and pulverization method or a wet method such as a suspension polymerization method, but can be produced using a wet method. In particular, it is preferable to prepare using an emulsion polymerization aggregation method. When using the emulsion polymerization aggregation method, specifically, a resin particle dispersion in which resin particles containing a polyester resin containing a biphenylalkylene oxide structure as described above are dispersed, and a colorant dispersion in which a colorant is dispersed. In the raw material dispersion liquid containing, it is preferable to produce through the aggregation process which forms an aggregated particle, and the fusion process which heats and aggregates an aggregated particle.
When a plurality of types of binder resins are used, a resin particle dispersion other than a resin particle dispersion in which resin particles containing a polyester resin containing a biphenylalkylene oxide structure are dispersed can be mixed with the raw material dispersion, and separated. When other components such as a mold agent are added to the toner, a dispersion in which the other components are dispersed can be mixed with the raw material dispersion.

-Adjustment of various dispersions-
The resin particles (emulsified particles) dispersed in the resin particle dispersion used in the aggregation step can be produced by dispersion suspension using a solvent, but the resin particles are produced in water without substantially using a solvent. It is preferable. The size of the resin particles is preferably in the range of 0.01 to 1 μm, more preferably in the range of 0.03 to 0.6 μm, and 0.03 to 0.4 μm in terms of the average particle size (volume average particle size). The range of is more preferable.

  In addition, when preparing a resin particle dispersion liquid by the emulsification process mentioned above, a dispersing agent can also be used for stabilization of a resin particle. Examples of the dispersant that can be used include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium octadecyl sulfate, sodium oleate, sodium laurate, and potassium stearate; laurylamine acetate, stearylamine acetate, lauryltrimethylammonium Cationic surfactants such as chloride; Zwitterionic surfactants such as lauryl dimethylamine oxide; Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl amine; Phosphoric acid Inorganic salts such as tricalcium, aluminum hydroxide, calcium sulfate, calcium carbonate, and barium carbonate can be used.

On the other hand, the colorant dispersion used in the agglomeration step is a colorant obtained by using, for example, a rotary shearing homogenizer, a media type dispersing machine such as a ball mill, a sand mill, or an attritor, or a high pressure opposed collision type dispersing machine. A liquid in which particles are dispersed can be prepared. Alternatively, a colorant dispersion can be obtained by dispersing a colorant in an aqueous system with a homogenizer using a polar surfactant.
In addition, the release agent dispersion used as necessary in the aggregation step is a dispersion of a release agent in water together with a polymer electrolyte such as an ionic surfactant, a polymer acid, or a polymer base. While being heated as described above, it can be adjusted by dispersing it into fine particles having a volume average particle diameter of 1 μm or less with a homogenizer or a pressure discharge type disperser (Gorin homogenizer, manufactured by Gorin) having a strong shearing ability.

-Aggregation process-
In the aggregation step, the resin particles, the colorant particles, and the like contained in the raw material dispersion are heated at a temperature slightly lower than the melting point of the resin constituting the resin particles to aggregate to form aggregated particles. Aggregated particles are formed by making the pH of the raw material dispersion acidic while stirring. As the said pH, the range of 2-6 is preferable, The range of 2.5-5 is more preferable, The range of 2.5-4 is further more preferable.
In forming the aggregated particles, it is also effective to use an aggregating agent. As the flocculant usable here, a surfactant having a polarity opposite to that of the surfactant used for the dispersant, an inorganic metal salt, and a metal complex having a valence of 2 or more can be preferably used. In particular, the use of a metal complex is particularly preferable because the amount of the surfactant used can be reduced and the charging characteristics are improved.

  Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and inorganic substances such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include metal salt polymers. Of these, aluminum salts and polymers thereof are particularly preferred. In order to obtain a sharper particle size distribution, the valence of the inorganic metal salt is bivalent than monovalent, trivalent than bivalent, trivalent than trivalent, and tetravalent than trivalent. The inorganic metal salt polymer is more suitable.

-Adhesion process-
After the aggregation process, the fusion process is performed. If necessary, an adhesion process is performed in which the aggregated particles obtained in the aggregation process are used as core particles, and resin particles are further adhered to the surface of the core particles to form a coating layer. May be implemented. Thereby, a toner having a so-called core / shell structure can be obtained.
The coating layer can be formed by usually adding a dispersion containing amorphous resin particles to the dispersion in which aggregated particles (core particles) are formed in the aggregation step.

-Fusion process-
In the fusion step, the pH of the suspension in which aggregated particles (or aggregated particles having a coating layer formed on the core particle surface) dispersed through the aggregation step (or adhesion step) are dispersed under the same stirring as in the aggregation step. By making the range of 3 to 9, the progress of aggregation is stopped, and the aggregated particles are fused by heating at a temperature equal to or higher than the melting point of the resin constituting the resin particles. The heating temperature at this time is not a problem as long as it is equal to or higher than the melting point of the resin constituting the resin particles. Moreover, as a heating time at this time, it should just be performed to the extent that fusion is fully made, and what is necessary is just to carry out for about 0.5 to 10 hours. In this way, a dispersion liquid in which fused particles (fused particles) are dispersed is obtained.
The fusion particle dispersion obtained in the fusion step is separated into solid particles by a solid-liquid separation step such as filtration, and toner particles are produced through a washing step and a drying step as necessary.

When a resin capable of a crosslinking reaction is used as the binder resin, the crosslinking reaction may be performed during heating at the time of fusion or after completion of the fusion. Moreover, a crosslinking reaction can also be performed simultaneously with fusion. In the case of carrying out a crosslinking reaction, for example, an unsaturated sulfonated crystalline polyester resin obtained by copolymerizing a double bond component as a resin capable of crosslinking reaction is used. Can be introduced.
Moreover, the polymerization initiator used in order to raise | generate a crosslinking reaction adds the liquid which melt | dissolved or emulsified this to various dispersion liquids (resin particle dispersion liquid etc.). A known crosslinking agent, chain transfer agent, polymerization inhibitor or the like may be added to the polymerization initiator for the purpose of controlling the degree of polymerization. The polymerization initiator may be mixed with the binder resin in advance before the emulsification step, or may be incorporated into the aggregated particles in the aggregation step.

-Various physical properties of toner-
The volume average particle diameter of the toner is preferably 2 to 12 μm, and more preferably 3 to 9 μm. The shape factor is preferably 115 to 140. If necessary, the particle size distribution may be adjusted through a classification process using an air classifier or the like.
The volume average particle diameter can be measured with an aperture diameter of 50 μm using, for example, a Coulter counter [TA-II] type (manufactured by Coulter). At this time, the measurement is performed after the toner to be measured is dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.

In the present invention, the volume average particle size (cumulative volume average particle size D ₅₀ ) and various average particle size distribution indices were measured using Coulter Counter TA-II (manufactured by Coulter Co., Ltd.) with an aperture diameter of 50 μm. The measurement was performed after the toner to be measured was dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed with ultrasonic waves for 30 seconds or more.
Here, the volume average particle size and various average particle size distribution indices are accumulated by drawing the cumulative distribution from the small diameter side in terms of volume and number for the particle size range (channel) divided based on the measured particle size distribution. The particle size of 16% is defined as volume D _16v and number D _16P , the particle size of 50% cumulative is _defined as volume D _50v and number D _50P , and the particle size of cumulative 84% is defined as volume D _84v and number D _84P . Using these, the volume average particle size distribution index (GSDv) is calculated as (D _84v / D _16V ) ^1/2 and the number average particle size distribution index (GSDp) is calculated as (D _84P / D _16P ) ^1/2 . Further, the small diameter side particle size distribution index GSDps is represented by D _50p / D _16p.

The shape factor is a value defined by the following equation (6).
・ Formula (6)
Shape factor = [(absolute maximum length of toner particles) ² ] / [(projected area of toner particles) × π × (1/4) × 100]
Here, the absolute maximum length of the toner diameter and the projected area of the toner were obtained by photographing a toner particle image magnified 500 times using an optical microscope (Nikon, Microphoto-FXA), and using the obtained image information via an interface. For example, the image was analyzed by introducing the image into an image analysis apparatus (Luzex III) manufactured by Nicole.
The value of the shape factor was calculated as an average value based on data obtained by measuring 1000 randomly sampled toner particles.
Further, the melting point of the toner is preferably in the range of 50 ° C. to 120 ° C., and preferably in the range of 60 to 110 ° C. When the melting point is less than 50 ° C., storage stability under a high temperature environment may be deteriorated, and when it exceeds 120 ° C., low temperature fixing may be difficult. The melting point of the toner can be measured in the same manner as the case of measuring the melting point of the binder resin using the differential scanning calorimeter described above.

<Electrophotographic developer>
The toner of the present invention described above can be used as a one-component developer composed only of toner or a two-component developer composed of carrier and toner. The electrophotographic developer of the present invention (hereinafter sometimes simply referred to as “developer”) will be described below.
The carrier that can be used in the developer of the present invention is not particularly limited, and a conventionally known carrier can be used regardless of whether it is a colored toner or a colorless toner. For example, a resin-coated carrier having a resin coating layer on the surface of the core material can be exemplified. Further, a resin-dispersed carrier in which a conductive material or the like is dispersed in a matrix resin may be used.
Coating resins and matrix resins used for carriers include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Examples thereof include, but are not limited to, acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins and the like.

Examples of the conductive material include metals such as gold, silver and copper, carbon black, titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. It is not limited.
Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to use the carrier for the magnetic brush method, it is a magnetic material. It is preferable.
The volume average particle size of the core material of the carrier is generally 10 to 500 μm, preferably 30 to 100 μm.

In order to coat the surface of the core material of the carrier with a resin, there may be mentioned a method of coating with a coating layer forming solution in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be appropriately selected in consideration of the coating resin to be used, coating suitability, and the like.
Specific resin coating methods include an immersion method in which the carrier core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed onto the surface of the carrier core material, and the carrier core material is fluidized air. And a kneader coater method in which the carrier core material and the coating layer forming solution are mixed in a kneader coater and the solvent is removed in a kneader coater.
The mixing ratio (mass ratio) of the toner of the present invention and the carrier in the developer of the present invention is preferably in the range of toner: carrier = 1: 100 to 30: 100, preferably about 3: 100 to 20: 100. A range is more preferred.

<Image forming method>
Next, the image forming method of the present invention will be described in detail.
The image forming method of the present invention is formed on the surface of the latent image holding body using a latent image forming step of forming an electrostatic latent image on the surface of the latent image holding body and a developer carried on the developer carrying body. A developing process for developing the electrostatic latent image to form a toner image, a transfer process for transferring the toner image formed on the surface of the latent image holding body to the surface of the recording medium, and a toner image transferred on the surface of the recording medium. In the image forming method including a heat fixing step, the developer for electrophotography of the present invention is used as the developer.

In order to form an image on the surface of the recording medium by the above-described process, a conventionally known electrophotographic image forming apparatus can be used.
As the image forming apparatus, a known electrophotographic image forming apparatus can be used. For example, a photoconductor (latent image holding body), a charging unit disposed opposite to the photoconductor, and an image forming apparatus are used. Image signal forming means for controlling the image signal, exposure means for exposing the photoconductor imagewise by the image signal from the image signal forming means to form a latent image, and the photosensitive material by a developer containing toner. Developing means for developing a latent image on the surface of the body to form a toner image, transfer means for transferring the toner image formed on the surface of the photoreceptor to a recording medium, and fixing means for fixing the toner image on the surface of the recording medium It is preferable to include.

Also, the apparatus may include an intermediate transfer member, and a secondary transfer unit that temporarily transfers the toner image on the photosensitive member to the intermediate transfer member and then secondarily transfers the toner image from the intermediate transfer member to the surface of the recording medium. preferable.
The photoreceptor is not particularly limited, and a conventionally known one can be used. The photoreceptor may have a single layer structure, or may have a multilayer structure and a function separation type. The material may be an inorganic photoconductor such as selenium or amorphous silicon, or an organic photoconductor (so-called OPC).

As the charging means, for example, a contact charging device using a conductive or semiconductive roller, brush, film, rubber blade, etc., a non-contact charging device such as corotron charging or scorotron charging using corona discharge, etc. Means known per se can be used.
As the exposure means, a conventionally known exposure means such as a combination of a semiconductor laser and a scanning device, a laser ROS comprising an optical system, or an LED head can be used. In order to realize a preferable mode of producing a uniform and high-resolution exposure image, it is preferable to use a laser ROS or an LED head.

As the image signal forming means, any conventionally known means can be used as long as a signal capable of forming a toner image at a desired position on the surface of the recording medium can be formed.
As the developing device means, a conventionally known developing device can be used regardless of one-component system or two-component system as long as it has a function of forming a uniform and high-resolution toner image on the latent image on the surface of the photoreceptor. it can. From the viewpoint of good graininess and smooth tone reproduction, a two-component developing device is preferable.

  As the transfer means, for example, a conductive or semiconductive roller, brush, film, rubber blade or the like to which a voltage is applied is used to create an electric field between the photosensitive member and the recording medium or the intermediate transfer member to be charged. A means for transferring a toner image made of toner particles, a corona charger using a corona discharge, a scorotron charger, etc., corona-charges the back surface of a recording medium or an intermediate transfer member to transfer a toner image made of charged toner particles. Conventionally known means such as means can be used.

As the intermediate transfer member, an insulating or semiconductive belt material or a drum-shaped one having an insulating or semiconductive surface can be used. A semiconductive belt material is preferable from the viewpoint of stably maintaining transferability during continuous image formation and reducing the size of the apparatus. As such a belt material, a belt material made of a resin material in which a conductive filler such as carbon fiber is dispersed is known. As this resin, for example, a polyimide resin is preferable.
As the secondary transfer means, for example, an electrically charged or semiconductive roller, brush, film, rubber blade, or the like to which a voltage is applied is used to create an electric field between the intermediate transfer member and the recording medium and to charge the toner. Known means such as a means for transferring a toner image made of particles, a means for transferring the toner image made of charged toner particles by corona charging the back surface of the intermediate transfer body with a corotron charger or a scorotron charger using corona discharge, etc. Can be used.
With the image forming apparatus as described above, a toner image can be formed on the surface of the recording medium.

  As the fixing unit, a conventionally known fixing unit can be used, and the toner image is heated by light irradiation with a flash lamp or the like, or a heat fixing device that fixes the toner image by heating and pressing such as a heating roll and a pressure roll. An optical fixing device that fixes the image can be used. The fixing device may have a configuration separated from the main body of the image forming apparatus.

-Image forming device-
Hereinafter, the configuration of the image forming apparatus used in the image forming method of the present invention will be described more specifically with reference to the drawings.
FIG. 2 is a schematic diagram showing an example of an image forming apparatus (tandem type image forming apparatus) used in the image forming method of the present invention. In FIG. 2, 21 is a main body housing, 22a to 22d are image forming units corresponding to four colors (yellow, magenta, cyan, and black), 23 is a belt unit (belt conveying device), 24 is a recording material supply cassette, 25 Is a recording material conveyance path, 30 is a photosensitive unit, 31 is a photosensitive drum, 32 is a charger (such as a charging roll), 33 is a developing unit, 34 is a drum cleaner, 35a to 35d are toner cartridges, and 40 is an exposure unit. , 42 is a polygon mirror, 51 is a primary transfer roll, 52 is a secondary transfer device, 53 is a belt cleaner, 62 is a take away roll, 63 is a registration roll (registration roll), 66 is a fixing device, 67 is a discharge roll, 68 is a storage tray, 71 is a density detection sensor (DC sensor), 72 is for controlling the image forming process. That controller, 231,232,233,234,235 is tension roll, 521 represents a second transfer roller.

  The schematic configuration of the image forming apparatus shown in FIG. 2 is such that image forming units 22a, 22b, 22c, and 22d corresponding to four colors are arranged in this order in the main body housing 21 in this order (in FIG. 2, from right to left). And an intermediate transfer belt 230 that is circulated and conveyed along the arrangement direction of the image forming units 22a to 22d for each color, and a tensioner that is provided on the inner peripheral side of the intermediate transfer belt 230 and stretches the intermediate transfer belt 230. A belt unit 23 including rolls 231, 232, 233, 234, and 235 is disposed, and a recording material (not shown) such as paper is accommodated below the image forming units 22 a, 22 b, 22 c, and 22 d. A recording material supply cassette 24 is disposed, and a recording material conveyance path 25 for conveying the recording material supplied from the recording material supply cassette 24 includes an image forming unit 22d and a belt. It is obtained by vertically disposed so as to be positioned on the left side of the knit 23.

  Each image forming unit 22 (22a-22d) is upstream of the intermediate transfer belt 230 in the circulation direction (clockwise direction; hereinafter, the position in the circulation direction may be abbreviated as downstream and the position in the reverse direction may be abbreviated as upstream). In this order, for example, toner images for yellow, magenta, cyan, and black (the arrangement is not necessarily in this order) are formed. Each of the image forming units 22a to 22d includes a photoconductor unit 30 and a developing unit 33, and includes an exposure unit 40 that is common to the image forming units 22a to 22d. Here, the photoreceptor unit 30 includes, for example, a photoreceptor drum 31, a charger (for example, a charging roll) 32 that charges the photoreceptor drum 31 in advance, and a drum cleaner 34 that removes residual toner on the photoreceptor drum 31. Are integrated into a cartridge.

  The developing unit 33 develops the electrostatic latent image exposed and formed by the exposure unit 40 on the charged photosensitive drum 31 with a corresponding color toner (for example, charged negatively). The developing units 33 for the respective colors are appropriately replenished with a developer from toner cartridges 35 (35a to 35d) corresponding to the respective colors. The details of the developing unit 33 and the toner cartridge 35 will be described later.

  On the other hand, the exposure unit 40 includes, for example, four semiconductor lasers (not shown), one polygon mirror 42, an imaging lens (not shown), and respective mirrors (corresponding to the respective photoreceptor units 30) in a unit case 41. (Not shown), laser light emitted from a semiconductor laser for each color component is deflected and scanned by a polygon mirror 42, and an optical image is formed on an exposure point on the corresponding photosensitive drum 31 via an imaging lens and mirror. Is to guide you.

In addition, the belt unit 23 has a configuration in which a plurality of stretching rolls 231, 232, 233, 234, and 235 are provided on the inner peripheral surface for stretching the intermediate transfer belt 230, and each photoconductor unit 30. The four primary transfer rolls 51 arranged to face the photosensitive drum 31 are arranged so as to press the inner peripheral surface of the intermediate transfer belt 230 through the intermediate transfer belt 230. When forming an image, a toner image formed on the photosensitive drum 31 is electrostatically applied to the outer peripheral surface of the intermediate transfer belt 230 by applying a voltage having a polarity opposite to the charging polarity of the toner to the primary transfer roll 51. Transcribed.
In the case of a high speed machine, the belt unit 23 can be driven at a speed of 260 to 400 mm / sec (the intermediate transfer belt 230 is rotated). In this case, A4 size (210 × 297 mm) recording paper is laterally fed. When used in (set so that the short side of the recording paper is in the transport direction), 60 to 120 images can be formed per minute.

Further, a secondary transfer device 52 is arranged at a portion corresponding to the stretching roll 235 that is arranged along the outer peripheral surface of the intermediate transfer belt 230 and provided on the downstream side of the image forming unit 22d located on the most downstream side. It is installed. By the secondary transfer device 52, the toner images (primary transfer images) of the respective colors that are superimposed and transferred on the intermediate transfer belt 230 so as to correspond to the original image information are secondarily transferred (collectively transferred) to the recording material. be able to. The secondary transfer device 52 is disposed on the toner image carrying surface side (outer peripheral surface) side of the intermediate transfer belt 230 and is disposed on the inner peripheral surface side of the intermediate transfer belt 230. A backup roll (a tension roll 235 functions as a backup roll in the image forming apparatus shown in FIG. 2) is provided as a counter electrode of the roll 521. The secondary transfer roll 521 is grounded, and a bias having the same polarity as the toner charging polarity is applied to the backup roll (stretching roll 235) via a power supply roll (not shown).
On the other hand, a belt cleaner 53 is disposed on the outer peripheral side of the intermediate transfer belt 230 on the further upstream side of the image forming unit 22 a located on the most upstream side of the intermediate transfer belt 230. Residual toner on the outer peripheral surface 230 can be removed.

The recording material delivered from the recording material supply cassette 24 is conveyed along a recording material conveyance path 25 provided in the image forming apparatus in a substantially vertical direction. A feed roll (not shown) for picking up a recording material, a take-away roll 62 for feeding out the recording material, and a recording material in order from the recording material supply cassette 24 side along the recording material conveyance direction of the recording material conveyance path 25. A registration roll (registration roll) 63, a secondary transfer device 52, a fixing device 66, and a discharge roll 67 for discharging a recording material are provided in this order in order to supply the secondary transfer portion at a predetermined timing. The recording material that has passed through the discharge roll 67 is finally stored in a storage tray 68 formed on the upper portion of the main body housing 21.
At the time of image formation, the recording material sent from the recording material supply cassette 24 is transferred onto the surface thereof by the secondary transfer device 52 on which the toner image transferred onto the intermediate transfer belt 230 is transferred. Further, the toner image transferred to the surface of the recording material is heated and melted by the fixing device 66 to be fixed on the surface of the recording material to form an image. Then, the recording material on which the image is formed is sent out to the storage tray 68 by the discharge roll 67.

  The image density detection sensor (DC sensor) 71 is disposed on the outer peripheral surface of the intermediate transfer belt 230 so as to be positioned between the image forming unit 22d and the secondary transfer device 52. The image density of the reference toner patch formed on the sensor is detected. The controller 72 that controls the image forming process is disposed at a position on the opposite side of the belt cleaner 53 from the side on which the tension roll 231 is provided.

  The fixing device 66 shown in FIG. 2 is a so-called two-roll fixing method fixing device that includes at least a heating roll and a pressure roll that presses against the heating roll to form a nip portion. Details of the fixing device will be described below.

  FIG. 3 is a schematic diagram showing an example of the configuration of a two-roll fixing type fixing device. In FIG. 3, 110 is a heating roll, 110a is a cylindrical cored bar (substrate), 110b is an elastic layer, and 110c is a mold release. Layer 111, heating roll 111a cylindrical core (base) 111b elastic layer 111c release layer 112c 113 heater lamp 114 unfixed toner image 115 recording sheet 115 oil Supply means, 118 is an inlet, 119 is an outlet.

Here, in the heating roll 110, an elastic layer 110b and a release layer 110c are laminated in this order on the surface of the base 110a, and a heater lamp 112 is built in the base 110a to form a nip portion with the heating roll. In the heating roll 111 arranged in such a manner, an elastic layer 111b and a release layer 111c are laminated in this order on the surface of the base 111a, and a heater lamp 113 is built in the base 111a. The heater lamp 113 may be omitted.
One of the heating rolls 110 and 111 is driven and rotated by a driving means (not shown), and the other is driven to rotate. The heating rolls 110 and 111 can rotate in the directions of arrows B and C, respectively. , C direction), a recording sheet 115 on which an unfixed toner image 114 is transported in the direction of arrow A by transport means (not shown) (the unfixed toner image 114 is a heating roll 110 of the recording sheet 115). Formed on the side in contact with the nip portion) enters the nip portion and is discharged to the paper discharge side (arrow B, C direction side) of the nip portion.

  Further, in order to prevent conveyance trouble such as clogging in the vicinity of the nip portion of the recording sheet 115, an inlet 118 that guides conveyance of the recording sheet 115 guides conveyance of the recording sheet 115 to the paper insertion side of the heating roll 111. It is provided to do. An outlet 119 made up of a pair of members for guiding the conveyance of the recording sheet 115 is provided on the paper discharge side of the nip portion so as to guide the conveyance of the recording sheet 115. Further, an oil supply means 116 for supplying silicone oil is disposed in contact with the surface of the heating roll 110. Note that the oil supply means 116 may be omitted when toner containing a release agent is used.

  In this fixing device, when the recording sheet 115 passes through the nip portion, the unfixed toner image 114 is fixed by being heated and pressed. At this time, since the silicone oil is supplied to the surface of the heating roll 110 by the oil supply means 116, sufficient releasability is ensured.

In addition to the two-roll fixing described above, the fixing device includes (1) a heating roll, a pressure belt that presses against the heating roll to form a nip portion, and faces the heating roll through the pressure belt. A belt nip roll fixing type fixing device provided with at least a pressure roll for pressurization, (2) a heating belt, a pressure member pressed from the inside of the heating belt, and the pressure applied via the heating belt A fixing device of a belt fixing system that includes at least a pressure roll that opposes a member and pressurizes, and a nip portion is formed between the heating belt and the pressure roll; or (3) a toner image is formed with the fixing belt. A pair of fixing members disposed opposite to each other with the fixing belt sandwiched between the fixing belts so as to form a fixing unit that heats and presses the recorded recording medium, and at least one of which has a heating function; And a cooling unit for cooling while conveying the recording medium having passed through the serial fixing portion while maintaining the fixing belt surface, can also be utilized, such as a fixing device including a.
The recording medium used in the image forming method of the present invention is not particularly limited, and may be a general copy paper or plain paper, or a resin sheet such as OHP paper.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

-Adjustment of resin dispersion-
<Synthesis of crystalline polyester resin A>
In a heat-dried three-necked flask, 100 parts by weight of dodecanedioic acid, 52 parts by weight of 1,9-nonanediol, and 30 parts by weight of a biphenylethylene oxide adduct (diol of n = 2 in the general formula (2)) After adding 0.13 part by weight of dibutyltin oxide as a catalyst, the air in the container was replaced with nitrogen gas by depressurization, and the atmosphere was inert, heated to 180 ° C. with mechanical stirring, and the system was uniform After forming a slurry, stirring was performed for 6 hours under a normal pressure nitrogen stream.

Thereafter, the temperature was gradually raised to 220 ° C. under reduced pressure, and the mixture was stirred for 4 hours. When it became viscous, it was air-cooled to stop the reaction and obtain a crystalline polyester resin A.
The weight average molecular weight (Mw) of the obtained crystalline polyester resin A was 38000 as measured by GPC (in terms of polystyrene).

  The molecular weight was measured under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)”, and the column uses two “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” THF (tetrahydrofuran) was used as an eluent. As experimental conditions, the sample concentration was 0.5%, and the flow rate was 0.6 ml / min. The experiment was conducted using a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

  Further, when the melting point (Tm) and the glass transition point (Tg) of the crystalline polyester resin A were measured using a differential scanning calorimeter (DSC) by the above-described measurement method, clear Tg and clear Tm were found. Tg = 33.4 ° C. and 94.0 ° C., and Tm = 112 ° C. The endothermic amount derived from the melting point Tm determined from the endothermic peak areas S (Tm) and S (Tg) obtained by DSC measurement (corresponding to the endothermic peak area S (Tm)) is 1.6 J / g, The total endothermic amount (corresponding to the endothermic peak area S (Tm) + S (Tg)) of 0 ° C. to 200 ° C. was 55.7 J / g.

<Preparation of crystalline polyester resin dispersion A>
The obtained crystalline polyester resin A was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A separately prepared aqueous medium tank is filled with 5% by weight diluted ammonia water obtained by diluting reagent ammonia water with ion-exchanged water, adjusted to pH 8.0, and heated to 120 ° C. with a heat exchanger every minute. At the rate of 0.1 liter, it was transferred to the Cavitron at the same time as the polyester resin melt. In this state, the Cavitron was operated under conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² to obtain a polyester resin dispersion A (resin particle concentration: 30% by weight) having an average particle size of 0.2 μm. It was.

<Synthesis of crystalline polyester resin B>
In a heat-dried three-necked flask, 100 parts by weight of adipic acid, 32 parts by weight of ethylene glycol, 47 parts by weight of biphenylethylene oxide adduct (diol of n = 2 in the general formula (2)), and dibutyltin as a catalyst After adding 0.18 parts by weight of oxide, the air in the container was replaced with nitrogen gas by depressurization, and the atmosphere was inert, heated to 180 ° C. with mechanical stirring, and the system became a uniform slurry. Thereafter, the mixture was stirred for 6 hours under a normal pressure nitrogen stream.
Then, it heated up gradually to 220 degreeC under pressure reduction, stirred for 4 hours, and air-cooled when it became a viscous state, and reaction was stopped. The obtained resin was designated as crystalline polyester resin B.
The weight average molecular weight (Mw) of the obtained crystalline polyester resin B was 36000 as measured by GPC (in terms of polystyrene).
Further, when the melting point (Tm) and the glass transition point (Tg) of the crystalline polyester resin B were measured using a differential scanning calorimeter (DSC) by the above-described measurement method, clear Tg and clear Tm were found. Tg = 33.4 ° C. and 94.0 ° C., and Tm = 110 ° C. The endotherm derived from the melting point Tm obtained from the areas S (Tm) and S (Tg) of the endothermic peaks obtained by DSC measurement is 2.8 J / g, and the total endotherm from 0 ° C. to 200 ° C. is 57. It was 5 J / g.

<Preparation of crystalline polyester resin dispersion B>
The obtained crystalline polyester resin B was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A separately prepared aqueous medium tank is filled with 5% by weight diluted ammonia water obtained by diluting reagent ammonia water with ion-exchanged water, adjusted to pH 8.0, and heated to 120 ° C. with a heat exchanger every minute. At the rate of 0.1 liter, it was transferred to the Cavitron at the same time as the polyester resin melt. In this state, the Cavitron was operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² to obtain a polyester resin dispersion B (resin particle concentration: 30% by weight) having an average particle diameter of 0.2 μm. It was.

<Synthesis of crystalline polyester resin C>
In a heat-dried three-necked flask, 100 parts by weight of dodecanedioic acid, 35 parts by weight of 1,9-nonanediol, and 60 parts by weight of a biphenylethylene oxide adduct (diol of n = 2 in the general formula (2)) After adding 0.13 part by weight of dibutyltin oxide as a catalyst, the air in the container was replaced with nitrogen gas by depressurization, and the atmosphere was inert, heated to 180 ° C. with mechanical stirring, and the system was uniform After forming a slurry, stirring was performed for 6 hours under a normal pressure nitrogen stream.
Then, it heated up gradually to 220 degreeC under pressure reduction, stirred for 4 hours, and air-cooled when it became a viscous state, and reaction was stopped. The obtained resin was designated as crystalline polyester resin C.
The obtained crystalline polyester resin C was insoluble in THF, and molecular weight measurement by GPC could not be performed.
Further, when the melting point (Tm) and the glass transition point (Tg) of the crystalline polyester resin C were measured by a differential scanning calorimeter (DSC) by the above-described measurement method, clear Tg and clear Tm were found. Tg = 104.6 degrees and Tm = 134 ° C. The endothermic amount derived from the melting point Tm obtained from the areas S (Tm) and S (Tg) of the endothermic peaks obtained by DSC measurement is 15.4 J / g, and the total endothermic amount from 0 ° C. to 200 ° C. is 49. 1 J / g.

<Preparation of crystalline polyester resin dispersion C>
The obtained crystalline polyester resin C was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A separately prepared aqueous medium tank is filled with 5% by weight diluted ammonia water obtained by diluting reagent ammonia water with ion exchange water, adjusted to pH 8.0, and then heated to 150 ° C. with a heat exchanger every minute. At the rate of 0.1 liter, it was transferred to the Cavitron simultaneously with the polyester resin melt. In this state, the Cavitron was operated under conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² to obtain a polyester resin dispersion C (resin particle concentration: 30% by weight) having an average particle diameter of 0.2 μm. It was.

<Synthesis of crystalline polyester resin D>
In a heat-dried three-necked flask, 100 parts by weight of adipic acid, 21 parts by weight of ethylene glycol, 94 parts by weight of a biphenylethylene oxide adduct (diol of n = 2 in the general formula (2)), and dibutyltin as a catalyst After adding 0.15 parts by weight of oxide, the air in the container was replaced with nitrogen gas by depressurization, and the atmosphere was inert, heated to 180 ° C. with mechanical stirring, and the system became a uniform slurry. Thereafter, the mixture was stirred for 6 hours under a normal pressure nitrogen stream.
Then, it heated up gradually to 220 degreeC under pressure reduction, stirred for 4 hours, and air-cooled when it became a viscous state, and reaction was stopped. The obtained resin was designated as crystalline polyester resin D.
The obtained crystalline polyester resin D was insoluble in THF, and molecular weight measurement by GPC could not be performed.
Further, when the melting point (Tm) and the glass transition point (Tg) of the crystalline polyester resin D were measured by a differential scanning calorimeter (DSC) by the above-described measurement method, clear Tg and clear Tm were found. , Tg = 107.6 degrees, and Tm = 137 ° C. The endotherm is 17.4 J / g derived from the melting point Tm obtained from the endothermic peak areas S (Tm) and S (Tg) obtained by DSC measurement, and the total endotherm from 0 ° C. to 200 ° C. is 50.1 J / G.

<Preparation of crystalline polyester resin dispersion D>
The obtained crystalline polyester resin D was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A separately prepared aqueous medium tank is filled with 5% by weight diluted ammonia water obtained by diluting reagent ammonia water with ion exchange water, adjusted to pH 8.0, and then heated to 150 ° C. with a heat exchanger every minute. At the rate of 0.1 liter, it was transferred to the Cavitron simultaneously with the polyester resin melt. In this state, the Cavitron was operated under the conditions that the rotational speed of the rotor was 60 Hz and the pressure was 5 kg / cm ² to obtain a polyester resin dispersion D (resin particle concentration: 30% by weight) having an average particle size of 0.2 μm. It was.

<Synthesis of crystalline polyester resin E>
100 parts by weight of dodecanedioic acid, 69 parts by weight of 1,9-nonanediol and 0.12 parts by weight of dibutyltin oxide as a catalyst were placed in a heat-dried three-necked flask, and then the air in the container was reduced by a vacuum operation. Was replaced with nitrogen gas, and an inert atmosphere was established. The mixture was heated to 180 ° C. under mechanical stirring to form a uniform slurry in the system, and stirred for 6 hours under a normal pressure nitrogen stream.
Then, it heated up gradually to 220 degreeC under pressure reduction, stirred for 4 hours, and air-cooled when it became a viscous state, and reaction was stopped. The obtained resin was designated as crystalline polyester resin E.
The weight average molecular weight (Mw) of the obtained crystalline polyester resin E was 14000 as measured by GPC (in terms of polystyrene).
Further, when the melting point (Tm) and the glass transition point (Tg) of the crystalline polyester resin C were measured by a differential scanning calorimeter (DSC) by the above-described measurement method, Tg was not seen and a clear Tm was observed. As seen, Tm = 74 ° C.

<Preparation of crystalline polyester resin dispersion E>
The obtained crystalline polyester resin E was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A separately prepared aqueous medium tank is filled with 5% by weight diluted ammonia water obtained by diluting reagent ammonia water with ion-exchanged water, adjusted to pH 8.0, and heated to 120 ° C. with a heat exchanger every minute. At the rate of 0.1 liter, it was transferred to the Cavitron at the same time as the polyester resin melt. In this state, the Cavitron was operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² to obtain a polyester resin dispersion E (resin particle concentration: 30% by weight) having an average particle diameter of 0.2 μm. It was.

<Synthesis of crystalline polyester resin F>
In a heat-dried three-necked flask, 100 parts by weight of adipic acid, 42 parts by weight of ethylene glycol, and 0.2 parts by weight of dibutyltin oxide as a catalyst were added, and the air in the container was replaced with nitrogen gas by a decompression operation. The mixture was heated to 180 ° C. under mechanical stirring and a uniform slurry was formed in the system, and stirred for 6 hours under a normal pressure nitrogen stream.
Then, it heated up gradually to 220 degreeC under pressure reduction, stirred for 4 hours, and air-cooled when it became a viscous state, and reaction was stopped. The obtained resin was designated as crystalline polyester resin F.
The weight average molecular weight (Mw) of the obtained crystalline polyester resin F was 18000 as measured by GPC (in terms of polystyrene).
Further, when the melting point (Tm) and the glass transition point (Tg) of the crystalline polyester resin C were measured by a differential scanning calorimeter (DSC) by the above-described measurement method, Tg was not seen and a clear Tm was observed. As seen, Tm = 47 ° C.

<Preparation of crystalline polyester resin dispersion F>
The obtained crystalline polyester resin F was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A separately prepared aqueous medium tank is filled with 5% by weight diluted ammonia water obtained by diluting reagent ammonia water with ion-exchanged water, adjusted to pH 8.0, and heated to 120 ° C. with a heat exchanger every minute. At the rate of 0.1 liter, it was transferred to the Cavitron at the same time as the polyester resin melt. In this state, the Cavitron was operated under conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² to obtain a polyester resin dispersion F (resin particle concentration: 30% by weight) having an average particle diameter of 0.2 μm. It was.

<Synthesis of Amorphous Polyester Resin G>
In a dry three-necked flask, 400 parts by weight of dimethyl terephthalate, 45.9 parts by weight of dimethyl 5-sulfoisophthalate, 118 parts by weight of 1.2-propanediol, 59 parts by weight of dipropylene glycol, and 23 parts by weight of diethylene glycol After adding 0.8 part by weight of dibutyltin oxide as a catalyst, the same treatment as in the case of synthesizing the crystalline polyester resin A was performed to obtain an amorphous polyester resin G.
The resulting amorphous polyester resin G had a weight average molecular weight (Mw) of 8400 as measured by GPC (in terms of polystyrene). Moreover, when the amorphous polyester resin G was measured by the above-mentioned measuring method using a differential scanning calorimeter (DSC), no clear peak was shown, and a stepwise endothermic change was confirmed. The glass transition point (Tg) at the midpoint of the stepwise endothermic change was 60 ° C.

<Preparation of amorphous polyester resin dispersion G>
The obtained amorphous polyester resin G was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A separately prepared aqueous medium tank is filled with 5% by weight diluted ammonia water obtained by diluting reagent ammonia water with ion-exchanged water, adjusted to pH 8.0, and heated to 120 ° C. with a heat exchanger every minute. At the rate of 0.1 liter, it was transferred to the Cavitron at the same time as the polyester resin melt. In this state, the Cavitron was operated under the conditions that the rotational speed of the rotor was 60 Hz and the pressure was 5 kg / cm ² to obtain a polyester resin dispersion G (resin particle concentration: 30% by weight) having an average particle size of 0.2 μm. It was.

<Adjustment of colorant dispersion>
Cyan pigment (manufactured by Dainichi Seika Co., Ltd., Pigment Blue 15: 3 (copper phthalocyanine)): 2300 parts by weight Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R): 150 parts by weight : 7700 parts by weight The above is mixed, dissolved, and dispersed by dispersing the colorant (cyan pigment) for about 1 hour using a high-pressure impact disperser Ultimateizer (manufactured by Sugino Machine, HJP30006). An agent dispersion was prepared. The average particle diameter of the colorant (cyan pigment) in the colorant dispersion was 0.15 μm, and the colorant particle concentration was 23% by mass.

<Adjustment of mold release agent dispersion>
Ester wax (Nippon Yushi Co., Ltd .: WEP-5): 50 parts by weight Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 5 parts by weight Ion exchange water: 200 parts by weight or more Was heated to 95 ° C. and dispersed using a homogenizer (manufactured by IKA: Ultra Tarrax T50), and then dispersed with a Manton Gorin high-pressure homogenizer (Gorin) to obtain a release agent having an average particle size of 230 nm. A release agent dispersion liquid (release agent concentration: 20% by mass) was prepared.

<Example 1>
-Production of Toner A-
Polyester resin dispersion A: 317 parts by weight Polyester resin dispersion G: 317 parts by weight Ion exchange water: 928 parts by weight Colorant dispersion: 42.65 parts by weight Release agent dispersion: 92.250 parts by weight Part / nonionic surfactant (IGEPAL CA897 / SC; solid content 20% by weight): 8.65 parts by weight The above raw material was placed in a 5 L cylindrical stainless steel container and stirred at a stirring speed of 400 rpm. An aqueous nitric acid solution was added dropwise to adjust the pH to 3.0. Thereafter, 36 parts by weight of a 1% aqueous solution of polyaluminum chloride as a flocculant was gradually added dropwise and dispersed and mixed for 5 minutes while applying a shearing force at 6000 rpm with Ultraturrax. When the viscosity of the raw material dispersion became uniform, it was set in a polymerization kettle.

The temperature was raised to 30 ° C. with a mantle heater, the stirring speed was adjusted to 400 rpm, and stirring was performed for 30 minutes. Next, it heated up to 60 degreeC with the temperature increase rate of +1 degreeC / min. At this time, the stirring speed was adjusted from 400 rpm to 250 rpm as the temperature increased. At this time, the volume average particle diameter of the aggregated particles measured using a Coulter counter [TA-II] type (aperture diameter: 50 μm; manufactured by Coulter, Inc.) was about 6.4 μm.
Subsequently, in order to fuse the aggregated particles and prevent the aggregated particles from being dispersed, a 1N sodium hydroxide aqueous solution was dropped to adjust the pH to 8.5. After the stirring speed was decreased from 250 rpm to 200 rpm, the temperature was increased to 96 ° C. at a temperature increase rate of + 1 ° C./min. While maintaining the shape of the particles with a microscope for 90 minutes at 96 ° C., the particles were cooled to 20 ° C. at a temperature decrease rate of −3 ° C./min.
Thereafter, the mixture was sieved with a 20 μm mesh, repeatedly washed with water, and then dried with a vacuum dryer. The volume average particle diameter of the toner A granulated as described above was 6.7 μm. The volume average particle size distribution index (GSDv) was 1.26, and the number average particle size distribution index (GSDp) was 1.27.

-Production of developer A-
The following two types of inorganic fine particles A and B were adhered to 100 parts by weight of the toner A with a high speed mixer.
Inorganic fine particles A: SiO ₂ (surface hydrophobized with silane coupling agent, average particle size 0.05 μm, added amount 1.0 part by weight)
Inorganic fine particle B: TiO ₂ (surface hydrophobized with silane coupling agent, average particle size 0.02 μm, refractive index 2.5, added amount 1.0 part by weight)
Further, the two-component developer of Example 1 was prepared by mixing 8 parts by weight of toner A to which the above external additive was added and 100 parts by weight of the same carrier as the cyan developer for DocuCentreColor 500 (Fuji Xerox Co., Ltd.). A was produced.

<Example 2>
A toner and a developer were prepared in the same manner as in Example 1 except that the type and amount of various dispersions used in the production of the toner and the amount of ion-exchanged water were changed as follows, and a developer B was obtained. .
Polyester resin dispersion B: 317 parts by weight Polyester resin dispersion G: 317 parts by weight Ion exchange water: 928 parts by weight Colorant dispersion: 42.65 parts by weight Release agent dispersion: 92.250 parts by weight Part

<Example 3>
A toner and developer were prepared in Example 1 except that the type and amount of various dispersions used in the production of the toner and the amount of ion-exchanged water were changed as follows, and Developer C was obtained.
Polyester resin dispersion C: 317 parts by weight Polyester resin dispersion G: 317 parts by weight Ion exchange water: 928 parts by weight Colorant dispersion: 42.65 parts by weight Release agent dispersion: 92.250 parts by weight Part

<Example 4>
A toner and a developer were prepared in Example 1 except that the type and amount of various dispersions used in the production of the toner and the amount of ion-exchanged water were changed as follows, and Developer D was obtained.
Polyester resin dispersion D: 317 parts by weight Polyester resin dispersion G: 317 parts by weight Ion exchange water: 928 parts by weight Colorant dispersion: 42.65 parts by weight Release agent dispersion: 92.250 parts by weight Part

<Comparative Example 1>
A toner and a developer were prepared in Example 1 except that the type and amount of various dispersions used in the production of the toner and the amount of ion-exchanged water were changed as follows, and Developer E was obtained.
Polyester resin dispersion E: 317 parts by weight Polyester resin dispersion G: 317 parts by weight Ion exchange water: 928 parts by weight Colorant dispersion: 42.65 parts by weight Release agent dispersion: 92.250 parts by weight Part

<Comparative example 2>
Example 1 A toner and a developer were produced in the same manner as in Example 1 except that the type and amount of various dispersions used in the production of the toner and the amount of ion-exchanged water were changed as follows.
Polyester resin dispersion F: 317 parts by weight Polyester resin dispersion G: 317 parts by weight Ion exchange water: 928 parts by weight Colorant dispersion: 42.65 parts by weight Release agent dispersion: 92.250 parts by weight Part

<Comparative Example 3>
A toner and a developer were prepared in Example 1 except that the type and amount of various dispersions used in the production of the toner and the amount of ion-exchanged water were changed as follows, and a developer G was obtained.
Polyester resin dispersion G: 634 parts by weight Ion exchange water: 928 parts by weight Colorant dispersion: 42.65 parts by weight Release agent dispersion: 92.250 parts by weight

-Image formation test-
Next, using the obtained developer, an image was formed by an image forming apparatus (Fuji Xerox Co., Ltd., DocuCentreColor500).
In addition, the fixing temperature was set to 140 ° C., and an evaluation image (solid image of 30 mm × 40 mm) of a Sian color (image density coverage 100%) was output to Fuji Xerox P paper, fixing property, Mechanical strength and heat resistance were evaluated.

The evaluation methods and evaluation criteria for fixability, mechanical strength, and heat resistance shown in Table 1 are as follows.
-Fixability-
The image surface of the solid image portion was valley-folded, and the degree of peeling of the image of the fold portion was visually observed and evaluated according to the following criteria.
○: No peeling was observed in the image of the crease part Δ: The peeling was seen only in the image of the crease part ×: The image was widely peeled off when the fold was opened

-Mechanical strength-
Using 5 types of metal rolls (radius = 40mm, 30mm, 20mm, 10mm, 5mm) with different radii, wrap the solid image part sequentially from the largest to the smallest, and visually observe the presence or absence of cracks. The minimum radius at which no cracks occurred was examined and evaluated according to the following criteria.
○: The minimum radius of the metal roll that does not crack is less than 10 mm. Δ: The minimum radius of the metal roll that does not crack is 10 mm or more and less than 30 mm. ×: The minimum radius of the metal roll that does not crack is 30 mm or more.

-Heat resistance-
In a state where two sheets of paper are overlapped so that the solid image portion and the solid image portion of the paper on which the solid image is formed are in contact, and a weight of 30 g / cm ² is added to the portion on which the image is formed, After putting in a thermostat kept at a constant temperature for 3 days, it was peeled back to room temperature of about 22 ° C., and the presence or absence of destruction of the image surface was visually observed.
This test was carried out by changing the temperature of the thermostatic chamber every 5 ° C. within the range of 40 to 65 ° C., and the minimum temperature at which the image surface was destroyed was evaluated according to the following criteria.
○: When the minimum temperature at which the image surface is destroyed is 60 ° C. or higher, or when the image surface is not destroyed even at 65 ° C. When the minimum temperature of destruction is 45 ° C or less

It is a figure explaining the area S (Tm) and S (Tg) of the endothermic peak measured with the differential scanning calorimeter. 1 is a schematic diagram illustrating an example of an image forming apparatus (tandem type image forming apparatus) used in an image forming method of the present invention. FIG. 2 is a schematic diagram illustrating a configuration example of a two-roll fixing type fixing device.

Explanation of symbols

21 Main body housings 22a to 22d Image forming unit 23 Belt unit (belt transport device)
24 Recording material supply cassette 25 Recording material conveyance path 30 Photoconductor unit 31 Photoconductor drum 32 Charger 33 (such as a charging roll) Developing unit 34 Drum cleaners 35a to 35d Toner cartridge 40 Exposure unit 41 Unit case 42 Polygon mirror 51 Primary transfer Roll 52 Secondary transfer device 53 Belt cleaner 62 Take away roll 63 Registration roll (Registration roll)
66 Fixing Device 67 Discharge Roll 68 Storage Tray 71 Concentration Detection Sensor (DC Sensor)
72 Controller 110 for Controlling Image Forming Process Heating Roll 110a Cylindrical Core (Base)
110b Elastic layer 110c Release layer 111 Heating roll 111a Cylindrical metal core (base)
111b Elastic layer 111c Release layer 112, 113 Heater lamp 114 Unfixed toner image 115 Recording sheet 116 Oil supply means 118 Inlet 119 Outlet 230 Intermediate transfer belt 231, 232, 233, 234, 235 Stretch roll 521 Secondary transfer roll

Claims (3)

An electrophotographic toner comprising: a polyester resin containing a biphenylalkylene oxide structure represented by the following general formula (1); and a colorant.

[In General Formula (1), n represents an integer of 2 or more. ]   An electrophotographic developer comprising the electrophotographic toner according to claim 1. A latent image forming step for forming an electrostatic latent image on the surface of the latent image holding member and a developer carried on the developer carrying member are used to develop the electrostatic latent image formed on the surface of the latent image holding member. A developing step for forming a toner image, a transfer step for transferring the toner image formed on the surface of the latent image carrier to the surface of the recording medium, and a fixing step for thermally fixing the toner image transferred to the surface of the recording medium. In an image forming method including:
The image forming method according to claim 2, wherein the developer is the electrophotographic developer according to claim 2.

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