JP2006276069A - Toner for electrophotography and its manufacturing method, developer for electrophotography using the same, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner for electrophotography which enables low-temperature fixing, makes it less likely for blocking to occur during storage and use in a development machine, and can suppress generation of filming of a development machine member, a carrier, and a latent image carrier. <P>SOLUTION: The toner for electrophotography contains a core layer, containing crystalline resin and a shell layer covering the core layer, with the toner for electrophotography being such that the core layer contains inorganic particles and the shell layer contains polyurea and/or polyurethane resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic toner used for image formation using an electrophotographic method such as a copying machine, a manufacturing method thereof, a developer and an image forming method using the same.

  Many methods are known as electrophotographic methods (see, for example, Patent Document 1). In general, a latent image is electrically formed by various means on the surface of a photoreceptor (latent image holding body) using a photoconductive substance, and the formed latent image is developed with toner. After the image is formed, the toner image may be transferred to the surface of a transfer medium such as paper, optionally via an intermediate transfer body, and fixed by heating, pressurization, heat pressurization, solvent vapor, or the like. An image is formed through the process. Further, the toner remaining on the surface of the photoreceptor is cleaned by various methods as necessary, and is used again for developing the toner image.

  As a fixing technique for fixing the toner image transferred to the surface of the transfer target, a hot roll fixing is performed in which the transfer target having the toner image transferred is inserted between a pair of rolls including a heating roll and a pressure roll and fixed. The law is common. As a similar technique, a fixing method in which one or both of the rolls is replaced with a belt is also known. These techniques, compared to other fixing methods, provide high-speed and robust images, high energy efficiency, and less harm to the environment due to volatilization of solvents and the like.

  On the other hand, the toner image transferred to the surface of the transfer medium through the transfer process is melted by being heated by the fixing member heated in the fixing process, and is fixed to the surface of the transfer target. It is known that in the fixing step, the toner image is not fixed unless the fixing member sufficiently heats not only the toner image but also the transfer target. If the transfer medium is not sufficiently heated, only the toner is melted by the heating from the fixing member, and a so-called cold offset is generated in which the toner adheres to the fixing member.

  Further, when the transfer target or the toner image is excessively heated, the viscosity of the toner is reduced, and so-called hot offset occurs in which part or all of the toner image adheres to the fixing member side. Therefore, it is necessary to set the fixing conditions so that both the cold offset and the hot offset do not occur when the fixing member is used to heat the transfer target or the toner image transferred to the surface thereof.

  On the other hand, in order to save power in the fixing process that occupies a certain amount of power consumption as the demand for energy saving required for image formation increases, and in order to expand the fixing conditions, the toner fixing temperature It is necessary to lower the temperature. By lowering the toner fixing temperature, in addition to the power saving and the expansion of the fixing conditions, the waiting time until the fixing temperature on the surface of the fixing member such as a fixing roll at the time of power input, that is, the so-called warm-up time is shortened. The time can be extended and the life of the fixing member can be extended.

  However, when the fixing temperature of the toner is lowered, the glass transition point of the toner particles is lowered at the same time, and it becomes difficult to achieve compatibility with the storage stability of the toner. In order to achieve both low temperature fixing and toner storage stability, it is necessary to have a so-called sharp melt property in which the viscosity of the toner rapidly decreases in a high temperature region while keeping the glass transition point of the toner at a higher temperature. .

  However, since the resin used for the toner usually has a certain range of glass transition point, molecular weight, etc., in order to obtain the sharp melt property, it is necessary to make the resin composition and molecular weight extremely uniform. In order to obtain such a highly uniform resin, it becomes necessary to adjust the molecular weight of the resin by using a special production method or by treating the resin with chromatography or the like. In this case, the cost for producing a highly uniform resin is inevitably high, and unnecessary resin (waste) is produced when producing a highly uniform resin, which is preferable from the viewpoint of environmental protection in recent years. Absent.

  On the other hand, if the copied images are stored over a long period of time, there may be a problem that a part or all of the images are transferred to the back of the upper stacked paper (hereinafter referred to as “document offset”). Sometimes). This phenomenon is particularly promoted when an image is stored under conditions of high temperature and high humidity, and the image storage stability is deteriorated. Therefore, an image forming method capable of maintaining a clear image under such conditions is desired.

  Therefore, there is a strong demand for an electrophotographic toner that is fixed at a low temperature and does not generate an offset up to a higher temperature region, so-called a wide fixing latitude, and an image forming method capable of obtaining an image that can withstand document offset.

  As a means for preventing the occurrence of offset, a method using a binder resin blended with a high molecular polymer or a crosslinked polymer (for example, see Patent Document 2, Patent Document 3, etc.) is known. By increasing the surface cohesive force, measures are taken to prevent toner fusion to the surface of the fixing member. However, although these methods are effective in preventing offset, there arises a problem that the fixing temperature rises.

  In order to improve the releasability from the surface of the fixing member, attempts have been made to add low molecular weight components such as polypropylene, polyethylene, alkylamide compounds, and ester compounds to the toner. However, although these methods can also improve the effect of offset resistance, blocking or the like is likely to occur due to long-term storage in a developing machine, and there is a concern about storage stability.

  On the other hand, as a means for lowering the toner fixing temperature, a technique of lowering the glass transition point of toner resin (binder resin) is generally performed. However, if the glass transition point is too low, powder aggregation (blocking) is likely to occur, and toner preservability on a fixed image is lost. Therefore, the lower limit of the glass transition point of the toner is practically 60 ° C. Although the glass transition point is a design point of many commercially available toner resins, at present, it has not been possible to obtain a toner that can be fixed at low temperature by the method of lowering the glass transition point. Although the fixing temperature can also be lowered by using a plasticizer, the toner may be blocked during storage or in the developing machine, or a part of the toner may be deposited on the developing machine member, carrier or latent image carrier. There was a problem that the filming phenomenon which adheres was easy to occur.

  A method using a crystalline resin as a binder resin has been known for a long time in order to achieve both blocking prevention, image storability, and low-temperature fixability (see, for example, Patent Document 4 and Patent Document 5). However, the crystalline resin is difficult to pulverize by the kneading pulverization method and has a low yield. Even if practicality in production can be secured, the fixing temperature can be lowered, but sufficient offset resistance cannot always be obtained. That is, although the melted toner penetrates into the paper, it has an effect of preventing the occurrence of offset, but the melted toner soaks into the paper so that a uniform and high density image cannot be obtained. . Further, since the glass transition temperature (Tg) of the resin is low, there is a problem that the externally added fine particles attached to the toner surface are easily embedded in the inside of the particle, resulting in poor fluidity and cleaning properties.

  As means for solving the above problems, many techniques for using a crystalline resin and an amorphous resin in combination, instead of using a crystalline resin alone as a binder resin, have been proposed. It is also known that when a toner is produced by a kneading pulverization method, pulverization is facilitated by the presence of an amorphous resin portion. For example, a method using a crystalline resin and an amorphous resin in combination (for example, see Patent Document 6), or a method using a resin in which a crystalline resin and an amorphous resin are chemically bonded (for example, Patent Document 7). To 11).

  However, when the amorphous resin is more than the crystalline resin, the amorphous resin becomes the continuous phase and the crystalline resin becomes the dispersed phase. In this case, the crystalline resin is covered with the amorphous resin. Therefore, while the problem due to the crystalline resin does not occur, the melting of the entire toner is governed by the softening temperature of the amorphous resin, so that it is difficult to achieve low-temperature fixability.

  As described above, in order to improve both the low-temperature fixability and the offset resistance, it is difficult to use a crystalline resin that is effective for the low-temperature fixability and the offset resistance in the melt-kneading pulverization method. However, there is a problem that sufficient performance cannot be obtained even if a resin having a high molecular weight or a crosslinked structure is used. Furthermore, since the pulverization is performed, it is difficult to control the shape of the toner particles. In particular, it is difficult to make the toner particles spherical, and it is difficult to reduce the toner particle size for the purpose of improving the image quality.

From the viewpoint of obtaining excellent powder characteristics such as blocking prevention, a capsule toner whose outer shell is made of a polyurethane resin or a polyurea resin has been proposed (Patent Document 12). In this technology, a hard resin such as a polyurethane resin or a polyurea resin is used for the outer shell, so that the powder characteristics are improved, and the outer shell is hard to be destroyed by stress applied in the developing machine. There is a merit.
Japanese Patent Publication No.42-23910 JP 50-134652 A JP-A-51-23354 Japanese Patent Publication No. 56-13943 Japanese Examined Patent Publication No.62-39428 Japanese Patent Laid-Open No. 2-79860 JP-A-1-163756 Japanese Patent Laid-Open No. 1-163757 JP-A-4-81770 JP-A-4-155351 JP-A-5-44032 JP-A-57-179860

  Therefore, if a crystalline resin is used for the core layer, and a hard resin such as polyurethane or polyurea resin is used for the outer shell (shell layer) that covers the core layer, it has excellent low-temperature fixability and anti-blocking properties, It can be expected to suppress ming. However, although the low-temperature fixability and the blocking resistance are improved, it has been found that a sufficient effect cannot be obtained for the occurrence of filming.

  An object of the present invention is to solve the above problems. That is, the present invention is an electrophotographic toner that can be fixed at low temperature, is difficult to block during storage or in use in a developing machine, and can suppress filming on a developing machine member, carrier, or latent image carrier. And a method for producing the same, an electrophotographic developer, and an image forming method.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1>
In an electrophotographic toner comprising a core layer containing a crystalline resin and a shell layer covering the core layer,
The toner for electrophotography, wherein the core layer contains inorganic particles and the shell layer contains polyurea and / or polyurethane resin.

<2>
The method for producing an electrophotographic toner according to <1>, wherein the method is produced by using interfacial polymerization.

<3>
A step of preparing an emulsion by dispersing an oily component containing at least the crystalline resin, the inorganic particles, and an isocyanate component in an aqueous solvent;
The method for producing an electrophotographic toner according to <2>, wherein the method is prepared through a step of interfacial polymerization by adding an amine component and / or an alcohol component to the emulsion.

<4>
An oily component containing at least an amine-forming substance that generates an amine component by reacting with the crystalline resin, the inorganic particles, an isocyanate component, and an aqueous solvent is dispersed in the aqueous solvent to perform interfacial polymerization simultaneously with emulsification. <2> The method for producing an electrophotographic toner according to <2>, wherein the toner is produced through a process.

<5>
An electrophotographic developer comprising the electrophotographic toner according to <1>.

<6>
A latent image forming step for forming an electrostatic latent image on the surface of the latent image carrier, and a developing step for developing the electrostatic latent image formed on the surface of the latent image carrier with a developer containing toner to form a toner image. And a transfer step of transferring the toner image formed on the surface of the latent image carrier to the surface of the recording medium, and a fixing step of thermally fixing the toner image transferred to the surface of the recording medium.
An image forming method, wherein the toner is the electrophotographic toner according to <1>.

  As described above, according to the present invention, low-temperature fixing is possible, it is difficult to block during storage or use in a developing machine, and filming on a developing machine member, a carrier, or a latent image carrier is also generated. An electrophotographic toner that can be suppressed, a method for producing the same, an electrophotographic developer, and an image forming method can be provided.

The electrophotographic toner of the present invention (hereinafter abbreviated as “toner”) is an electrophotographic toner comprising a core layer containing a crystalline resin and a shell layer covering the core layer, wherein the core layer contains inorganic particles. The shell layer contains polyurea and / or polyurethane.
Therefore, the toner of the present invention can be fixed at low temperature because the core layer contains a crystalline resin, and the shell layer contains polyurea and / or polyurethane resin, so that blocking during storage or use in a developing machine is also possible. Can be suppressed.
In the toner of the present invention, since the shell layer contains polyurea and / or polyurethane resin, even if a crystalline resin contained in the conventional core layer has a lower melting point, the storage stability is hardly deteriorated, Low temperature fixability and blocking resistance can be achieved at a higher level.

On the other hand, as described in Patent Document 12, when the shell layer is made of a hard resin such as a polyurea resin or a polyurethane resin, the toner is hardly destroyed in the apparatus, and is generated by the destruction of the toner. Filming with fine powder is considered to be suppressed.
However, when the core layer is a soft crystalline resin having a low melting point, when stress is applied to the toner in the apparatus, the shell layer is supported from the inside to reduce its physical deformation, and the shell layer is externally applied. The effect of dispersing applied stress is weakened. Furthermore, such an effect is further weakened when a crystalline resin having a lower melting point is used in order to cope with energy savings required in recent years.

  That is, when the core layer contains a crystalline resin, even if the resin constituting the shell layer is hard, when the stress is applied to the toner, the stress is concentrated by the shell layer, and the toner It is considered that film breakage is likely to occur, and as a result, filming is likely to occur.

However, since the toner of the present invention includes inorganic particles in the core layer, the inorganic particles existing inside the toner act as fillers, and the core layer is placed inside the shell layer while maintaining the fixing property of the crystalline resin. Therefore, the effect of supporting the toner particles can be enhanced and the strength of the toner particles can be maintained. For this reason, even when stress is applied from the outside, the toner is not easily destroyed, and the occurrence of filming can be suppressed.
Further, the inorganic particles present in the vicinity of the interface between the core layer and the shell layer also have an effect of improving the adhesion between the core layer and the shell layer due to the hydroxyl group contained in the inorganic particles. For this reason, even if the shell layer of the toner is destroyed due to external stress, the broken shell layer is difficult to drop off from the core layer, so that filming due to peeling of the broken shell layer is prevented. You can also.

This is because the hydroxyl group has a high affinity for the crystalline resin contained in the core layer and the polar resin such as the polyurea resin and polyurethane resin contained in the shell layer. This is because the adhesion between the core layer and the shell layer can be improved when it exists in the vicinity of the interface between the core layer and the shell layer.
In addition, it is expected that a part of the hydroxyl groups of the inorganic particles react with the functional group of the resin contained in the core layer or shell layer to further improve the adhesion.

-Crystalline resin-
In the differential scanning calorimetry (DSC), the crystalline resin used in the present invention is a resin having a clear endothermic peak, not a stepwise endothermic amount change. Specifically, the half-value width of the endothermic peak is 15 ° C. or less, and preferably 10 ° C. or less. Further, as the crystalline resin, a crystalline polyester is particularly preferable because it gives a good melting point and hardness for fixing.
The crystalline polyester is composed of an acid-derived constituent component and an alcohol-derived constituent component. As the acid-derived constituent component, an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid are preferable, and among them, an aliphatic dicarboxylic acid is desirable, and a linear carboxylic acid is particularly preferable. Acid is desirable.

  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. Among these, considering availability, sebacic acid and 1,10-decanedicarboxylic acid are preferable.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, etc. Among them, terephthalic acid is an easily available, low melting point polymer. It is preferable in terms of easy formation.

As the acid-derived constituent component, in addition to the aforementioned aliphatic dicarboxylic acid-derived constituent component and aromatic dicarboxylic acid-derived constituent component, a dicarboxylic acid-derived constituent component having a double bond, a dicarboxylic acid-derived constituent component having a sulfonic acid group, etc. Are preferably included.

  The component derived from a dicarboxylic acid having a double bond is derived from a lower alkyl ester or acid anhydride of a dicarboxylic acid having a double bond, in addition to a component derived from a dicarboxylic acid having a double bond. Components are also included. The dicarboxylic acid-derived component having a sulfonic acid group is derived from a lower alkyl ester or acid anhydride of a dicarboxylic acid having a sulfonic acid group, in addition to a component derived from a dicarboxylic acid having a sulfonic acid group. Components are also included.

  The dicarboxylic acid having a double bond can be suitably used to prevent hot offset at the time of fixing since the entire resin can be crosslinked using the double bond. Examples of such dicarboxylic acids include, but are not limited to, fumaric acid, maleic acid, 3-hexenedioic acid, and 3-octenedioic acid. Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, fumaric acid, maleic acid and the like are preferable in terms of cost.

The dicarboxylic acid having a sulfonic acid group is effective in that it can favorably disperse a colorant such as a pigment. Also, in the preparation of toner, when the entire resin is emulsified or suspended in water to produce fine particles, if there are sulfonic acid groups, as described later, emulsification or suspension can be performed without using a surfactant. It is. Examples of such a dicarboxylic acid having a sulfone group include, but are not limited to, 2-sulfoterephthalic acid sodium salt, 5-sulfoisophthalic acid sodium salt, and sulfosuccinic acid sodium salt.
Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, 5-sulfoisophthalic acid sodium salt is preferable in terms of cost.

  All of these acid-derived components other than aliphatic dicarboxylic acid-derived components and aromatic dicarboxylic acid-derived components (dicarboxylic acid-derived components having double bonds and dicarboxylic acid-derived components having sulfonic acid groups) As content in an acid origin structural component, 1-20 structural mol% is preferable and 2-10 structural mol% is more preferable.

When the content is less than 1 component mol%, the pigment dispersion is not good, the emulsified particle size becomes large, and it may be difficult to adjust the particle size of the core particles by aggregation. If it exceeds 50%, the crystallinity of the polyester resin is lowered, the melting point is lowered, the storage stability of the image is deteriorated, or the emulsified particle diameter is too small to dissolve in water, and latex may not be produced.
In the present specification, “constituent mol%” refers to a percentage when each constituent component (acid-derived constituent component or alcohol-derived constituent component) in the crystalline polyester resin is defined as one unit (mol).

  Further, as the aforementioned alcohol-derived component, specifically, an aliphatic diol is preferable, and a linear aliphatic diol having a chain carbon number of 7 to 20 is more preferable. When the aliphatic diol is branched, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that the toner blocking resistance, the image storage stability, and the low-temperature fixability may be deteriorated. When the chain carbon number is less than 7, when polycondensation with an aromatic dicarboxylic acid, the melting point becomes high and low-temperature fixing may be difficult. It tends to be difficult to obtain. The chain carbon number is more preferably 14 or less.

  Further, when a polyester is obtained by condensation polymerization with an aromatic dicarboxylic acid, the chain carbon number is preferably an odd number. When the chain carbon number is an odd number, the melting point of the polyester resin is lower than when the chain carbon number is an even number, and the melting point tends to be a value within the numerical range described later.

  Specific examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,7-heptanediol. 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol 1,18-octadecanediol, 1,20-eicosanediol, and the like, but are not limited thereto. Among these listed above, 1,8-octanediol, 1,9-nonanediol and 1,10-decanediol are preferable in view of availability, and 1,9-nonane is preferred because of its low melting point. Diols are preferred.

  The alcohol-derived constituent component has an aliphatic diol-derived constituent component content of 80 constituent mol% or more, and may contain other components as necessary. As the alcohol-derived constituent component, the content of the aliphatic diol-derived constituent component is preferably 90 constituent mol% or more.

When the content of the aliphatic diol-derived constituent component is less than 80 constituent mol%, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that the blocking resistance, the image storage stability, and the low-temperature fixability are deteriorated. May end up.
Other components included as necessary include diol-derived components having double bonds and diol-derived components having sulfonic acid groups.

Examples of the diol having a double bond include 2-butene-1,4-diol, 3-butene-1,6-diol, 4-butene-1,8-diol, and the like.
Examples of the diol having a sulfonic acid group include 1,4-dihydroxy-2-sulfonic acid benzene sodium salt, 1,3-dihydroxymethyl-5-sulfonic acid benzene sodium salt, and 2-sulfo-1,4-butanediol sodium. Examples include salts.

  When adding these alcohol-derived components other than aliphatic diol-derived components (diol-derived component having a double bond and diol-derived component having a sulfonic acid group), the content in these alcohol-derived components Is preferably 1 to 20 mol%, more preferably 2 to 10 mol%.

  When the content of the alcohol-derived constituent component other than the aliphatic diol-derived constituent component is less than 1 constituent mol%, the pigment dispersibility when using a pigment as the colorant may be deteriorated, whereas the 20 constituent If it exceeds mol%, the crystallinity of the polyester resin is lowered, the melting point is lowered, the storage stability of the image is deteriorated, the emulsified particle diameter is too small and the polymer is dissolved in water, and latex may not be produced.

Further, the crystalline resin used in the present invention preferably contains a crystalline polyester resin having an ester concentration M defined by the following formula (1) of 0.01 or more and 0.12 or less as a main component.
Formula (1) M = K / A
In the formula (1), M represents the ester concentration, K represents the number of ester groups (average number per molecule) contained in the crystalline polyester resin, and A represents the polymer chain of the crystalline polyester resin. The number of constituent atoms (average number per molecule) is represented.

  Here, the above-mentioned “ester concentration M” is one index indicating the ester group content in the polymer of the crystalline polyester resin. The “number of ester groups contained in the crystalline polyester resin” represented by K in the formula (1) refers to the number of ester bonds contained in the whole crystalline polyester resin.

  The “number of atoms constituting the polymer chain contained in the crystalline polyester resin” represented by A in the formula (1) is the total number of atoms constituting the polymer chain of the crystalline polyester resin, and is an ester bond. It includes all the atoms involved in, but does not include the number of atoms in the branched portion in other constituent sites. That is, carbon atoms and oxygen atoms derived from carboxyl groups and alcohol groups involved in ester bonds (two oxygen atoms in one ester bond) and the six carbons constituting the polymer chain, for example, in the aromatic ring, Although included in the calculation of the number of atoms, for example, a hydrogen atom in an aromatic ring or an alkyl group, or an atom or atomic group of a substituent thereof constituting the polymer chain is not included in the calculation of the number of atoms.

  Explaining with a specific example, among the total of 10 atoms of 6 carbon atoms and 4 hydrogen atoms in the arylene group constituting the polymer chain, the above-mentioned “constituting the polymer chain contained in the crystalline polyester resin” The number of atoms to be included is only six of carbon atoms, and even if the hydrogen is replaced by any substituent, the atoms constituting the substituent are It is not included in the “number of atoms constituting the included polymer chain”.

The crystalline polyester resin has one repeating unit (for example, when the polymer is represented by H— [OCOR ¹ COOR ² O—] _n —H, the one repeating unit is represented in []). In the case of a single polymer consisting of only two ester bonds in one repeating unit (that is, the number of ester groups K ′ = 2 in the repeating unit), the ester concentration M is expressed by the following formula: (1-1).
Formula (1-1) M = 2 / A ′
In the above formula (1-1), M represents the ester concentration, and A ′ represents the number of atoms constituting the polymer chain in one repeating unit.

When the crystalline polyester resin is a copolymer composed of a plurality of copolymer units, the number of ester groups K ^X and the number of atoms A ^X constituting the polymer chain are determined for each copolymer unit, It can be obtained by multiplying the polymerization ratios and summing them up and substituting them into the formula (1). For example, the compound [(Xa) _a (Xb) _b (Xc)] has three copolymerized units of Xa, Xb and Xc, and the copolymerization ratio thereof is a: b: c (where a + b + c = 1). _c ] can be determined by the following formula (1-2).
Formula (1-2) M = {K ^Xa × a + K ^Xb × b + K ^Xc × c} / {A ^Xa × a + A ^Xb × b + A ^Xc × c}

In the above formula (1-2), M represents the ester concentration, K ^Xa represents the copolymer unit Xa, K ^Xb represents the copolymer unit Xb, and K ^Xc represents the number of each ester group in the copolymer unit Xc, and A ^Xa represents copolymer unit Xa, A ^Xb represents copolymer unit Xb, and A ^Xc represents the number of atoms constituting each polymer chain in copolymer unit Xc.

  When the ester concentration M is less than 0.01, the chargeability is good, but the melting point of the crystalline polyester resin becomes too high, and the low temperature fixability may not be obtained. The lower limit of the ester concentration M is more preferably 0.04 or more.

  On the other hand, if the ester concentration M exceeds 0.12, the charging property is lowered, and the melting point of the crystalline polyester resin is too low, so that the stability of the fixed image and the powder blocking property are lowered. . The upper limit of the ester concentration M is more preferably 0.10 or less.

In the core layer, a crystalline resin is always used as the binder resin, and in particular, the crystallinity having an ester concentration M defined by the above formula (1) of 0.01 or more and 0.12 or less as described above. A polyester resin (hereinafter sometimes simply referred to as “specific polyester resin”) is preferably contained as a main component.
Here, the “main component” refers to the main component of the binder resin contained in the core layer. Specifically, the component constituting 50% or more of the total binder resin contained in the core layer. Point to. However, in the present invention, among all the binder resins contained in the core layer, the specific polyester resin is preferably 70% or more, more preferably 90% or more, and all are specific polyester resins. It is particularly preferred.

As melting | fusing point of crystalline polyester resin, it is preferable that it is 60-120 degreeC, and it is more preferable that it is 70-100 degreeC.
When the melting point is less than 60 ° C., powder aggregation tends to occur and the stability of a fixed image may deteriorate. On the other hand, when the melting point exceeds 120 ° C., low-temperature fixing may not be possible.
The melting point of the crystalline resin is, for example, the value at the top of the endothermic peak when measured from a room temperature to 150 ° C. at a rate of temperature increase of 10 ° C. per minute using a differential scanning calorimeter (DSC). Can do.

  The method for producing the crystalline polyester resin is not particularly limited, and can be produced by a general polyester polymerization method in which an acid component and an alcohol component are reacted as described above. For example, direct polycondensation, transesterification method Etc. are produced using different types depending on the type of monomer. The molar ratio (acid component / alcohol component) when the acid component reacts with the alcohol component varies depending on the reaction conditions and the like, and cannot be generally stated, but is usually about 1/1.

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

  Catalysts that can be used in the production of the crystalline polyester resin include alkali metal compounds such as sodium and lithium, alkaline earth metal compounds such as magnesium and calcium, metals such as zinc, manganese, antimony, titanium, tin, zirconium and germanium. Examples include compounds, phosphorous acid compounds, phosphoric acid compounds, and amine compounds. Specific examples include the following compounds.

  For example, sodium acetate, sodium carbonate, lithium acetate, lithium carbonate, calcium acetate, calcium stearate, magnesium acetate, zinc acetate, zinc stearate, zinc naphthenate, zinc chloride, manganese acetate, manganese naphthenate, titanium tetraethoxide, titanium Tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, antimony trioxide, triphenylantimony, tributylantimony, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, zirconium tetrabutoxide, naphthene Zirconate, zirconyl carbonate, zirconyl acetate, zirconyl stearate, zirconyl octylate, germanium oxide, triphenyl Phosphite, tris (2,4-di -t- butyl-phenyl) phosphite, ethyltriphenylphosphonium bromide, triethylamine, compounds such as triphenyl amine.

In the core layer, other known binder resins other than the crystalline polyester resin can be used together as necessary.
Specifically, polyacrylates such as polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, 2-ethylhexyl polyacrylate, lauryl polyacrylate, polymethyl methacrylate, polybutyl methacrylate, poly Methacrylic acid hexyl, polymethacrylic acid 2-ethylhexyl, polymethacrylic acid ester polymer such as polylauryl methacrylate, copolymer of acrylic acid ester and methacrylic acid ester, styrenic monomer and acrylic acid ester or methacrylic acid ester Copolymer, Polyethylene acetate, Polypropionate, Polybutyrate, Ethylene polymers such as polyethylene and polypropylene and their copolymers, Styrene-butadiene copolymer, Styrene-isoprene copolymer, Styrene-polymer Styrene copolymers such as in acid copolymers, polyvinyl ethers, polyvinyl ketones, polyesters, polyamides, polyurethanes, rubbers, epoxy resins, polyvinyl butyral, rosin, modified rosin, terpene resins, and phenol resins.

-Inorganic particles-
As the inorganic particles used in the present invention, known inorganic particles can be used, but inorganic particles made of a metal oxide are preferable.
In addition, it is more preferable that the inorganic particles having many hydroxyl groups on the surface are appropriately hydrophobically treated so that the toner can be stably contained. In addition, even if the inorganic particles with many hydroxyl groups on the surface are hydrophobized, the hydroxyl groups are not lost on the surface, so the effect of improving the adhesion by the inorganic particles in the vicinity of the interface between the core layer and the shell layer is sufficiently secured. Is done.

Examples of inorganic particles made of metal oxide include titanium oxide, silicon oxide, aluminum oxide, and zirconium oxide.
In addition, when the inorganic particles are subjected to a hydrophobizing treatment, a generally known method is used, but a coupling treatment is more preferred, and a silane coupling treatment, a titanate coupling treatment, an aluminate coupling treatment, etc. are more preferred. Can be used.

The average particle size of the inorganic particles is preferably in the range of 0.005 to 0.5 μm, and preferably in the range of 0.01 to 0.1 μm. When the average particle diameter is less than 0.005 μm, the inorganic particles may aggregate in the toner, and when it exceeds 0.5 μm, filming may occur.
Further, the content of inorganic particles contained in the toner is preferably in the range of 1 to 20% by weight, and more preferably in the range of 2 to 10% by weight. When the content is less than 1% by weight, the toner may be destroyed by applying stress in the apparatus, and filming may occur. On the other hand, if it exceeds 10% by weight, the fixability of toner onto a recording medium such as paper may be weakened.

-Colorant-
In the toner of the present invention, a colorant is added to the core layer. Known dyes and pigments can be used as the colorant, but pigments are preferably used from the viewpoint of light resistance and water resistance.
As the pigment, a known organic or inorganic pigment can be used. For example, carbon black such as furnace black, channel black, acetylene black, thermal black, inorganic pigments such as bengara, bitumen, titanium oxide, fast yellow, disazo yellow, pyrazolone red, chelate red, brilliant carmine, para brown, benzimidazolone Azo pigments such as copper phthalocyanine and metal-free phthalocyanine, condensed polycyclic pigments such as flavantron yellow, dibromoanthrone orange, perylene red, quinacridone red and dioxazine violet, and carmine lake pigments.

When the toner of the present invention is used as a magnetic toner, all or part of the colorant can be replaced with magnetic powder. As the magnetic powder, magnetite, ferrite, or a simple metal such as cobalt, iron, nickel, or an alloy thereof can be used.
These colorants are added at a ratio of about 1 to 50 parts by weight, preferably 2 to 20 parts by weight, with respect to 100 parts by weight of all binder resin components constituting the core layer and the shell layer.

When a pigment is used as a colorant when the toner of the present invention is obtained by a wet manufacturing method as described later, it is necessary to adjust a pigment dispersion in which a pigment is dispersed in a solvent.
Here, as a pigment dispersion method, a media-type disperser such as a sand mill, a ball mill, an attritor or a coball mill, a roll mill such as a three roll mill, a cavitation mill such as a nanomizer, a colloid mill, or the like can be used. In order to apply an appropriate shearing force at the time of pigment dispersion, the viscosity may be adjusted by adding a part of a crystalline resin.

Moreover, it is preferable to add a pigment dispersant in order to keep the dispersion state of the pigment in the pigment dispersion stable.
Specific examples of the pigment dispersant include EFKA47, EFKA4009, EFKA4010 (modified polyurethane: EFKA CHEMICALS), Ajisper PB711, Ajisper PB411, Ajisper PA111 (Ajinomoto Co., Ltd.), Disparon DA-703-50, Disparon DA-705, disparon DA-725, disparon DA-400N (polyester: manufactured by Enomoto Kasei Co., Ltd.), and the like.

In order to further stabilize the pigment dispersion, it is preferable to add a pigment derivative or the like, or to disperse the pigment after the surface treatment of the pigment.
Specific examples of pigment derivatives include dimethylaminoethylquinacridone, dihydroquinacridone, sulfonic acid derivatives of anthraquinone, carboxylic acid derivatives of anthraquinone, Solsperse 5000, Solsperse 12000, Solsperse 22000 (manufactured by Geneca), EFKA-745, LP6750 (EFKA). Chemicals).

  The pigment surface treatment agents include natural rosins such as gum rosin, wood rosin and tall rosin, and abietic acid derivatives such as abietic acid, levopimaric acid and dextropimalic acid, and metal salts such as calcium salts, sodium salts, potassium salts and magnesium salts thereof. Rosin / maleic acid resin, rosin / phenol resin and the like. The amount of the pigment derivative and the pigment surface treatment agent is preferably from 0.1 to 100% by weight, particularly preferably from 0.1 to 10% by weight, based on the pigment.

-Release agent-
The toner of the present invention may contain a release agent. In this case, the release agent is preferably contained in the core layer.
The toner contains a release agent, so that the releasability at the time of fixing is improved. In the contact heating type fixing method, the release oil applied to the fixing roll is reduced or no release oil may be used; That is, oilless fixing is possible. For this reason, it is possible to avoid a reduction in the life of the fixing roll due to the release oil and the occurrence of defects such as oil streaks, and also to reduce the cost of the fixing device.

  As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; carnauba Plant waxes such as wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; mineral and petroleum systems such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax And waxes; ester waxes such as fatty acid esters, montanic acid esters, carboxylic acid esters, pentaerythritol, higher alcohol esters; and the like. These waxes can be used in combination of two or more.

The melting point of the release agent is preferably in the range of 50 to 120 ° C., and more preferably below the melting point of the crystalline resin.
When the melting point of the release agent is less than 50 ° C., the change temperature of the release agent is too low, the blocking resistance may be inferior, and the developability may deteriorate when the temperature in the copying machine increases. On the other hand, when the melting point exceeds 120 ° C., the change temperature of the release agent is too high, and the low-temperature fixability of the crystalline resin may be impaired. The melting point of the release agent can be measured by the same method as the melting point of the crystalline resin.

The release agent is preferably contained in the toner within a range of 4 to 22% by weight, and more preferably within a range of 6 to 16% by weight.
If the content of the release agent is less than 4% by weight, there may be no effect of addition of the release agent. If it exceeds 22% by weight, the chargeability tends to be adversely affected, and the toner is easily destroyed inside the developing device, so that the release agent or binder resin becomes spent on the carrier, and the charge tends to decrease. In some cases, effects such as

-Other internal additives-
Other known internal additives other than the colorant and release agent can be added to the toner of the present invention, and these internal additives are preferably contained in the core layer.
For example, a charge control agent may be used as an internal additive, and those conventionally used in developers can be used. However, metal salts of benzoic acid and salicylic acid used in powder toners for xerography can be used. Metal salt, metal salt of alkylsalicylic acid, metal salt of catechol, metal-containing bisazo dye, tetraphenylborate derivative, quaternary ammonium salt, alkylpyridinium salt, resin type charge containing polar group A control agent and a combination of these can be preferably used. The amount of these charge control agents added to the toner solid content is generally in the range of 10% by weight or less.

-Manufacturing method of shell layer and toner-
The method for producing the toner of the present invention is not particularly limited, but is preferably a method using a known interfacial polymerization method, such as JP-A-57-179860 and JP-A-58-66948. The methods described in JP-A Nos. 59-148066 and 59-162562 can be used.
.
For example, after forming a shell layer by interfacial polymerization in a solution in which a monomer component of polyurethane and / or polyurea, a monomer component of a crystalline resin forming a core layer, and a component such as inorganic fine particles are dispersed, a crystal layer is subsequently formed. A method of forming a core layer by polymerizing the monomer component of the conductive resin (first production method).

Alternatively, a step of preparing an emulsion by dispersing an oily component containing at least a crystalline resin, inorganic particles, and an isocyanate component in an aqueous solvent, and adding an amine component and / or an alcohol component to the emulsion And a step of performing interfacial polymerization (second production method).
In addition, as a raw material used for adjusting the emulsion, a solution in which a colorant, a release agent, or the like is dispersed can be used. In preparing the emulsion, a low boiling point solvent is used. In this production method, an isocyanate component in a particulate oily component that forms a core layer dispersed in an emulsion, and an amine component and / or an alcohol component added after the preparation of the emulsion is an interface between the particulate oily components. To form a shell layer containing polyurea and / or polyurethane.

  As the low boiling point solvent, those having a boiling point of 100 ° C. or less can be used. For example, n-pentane, methylene chloride, ethylene chloride, carbon disulfide, acetone, methyl acetate, ethyl acetate, chloroform, methyl alcohol, Examples thereof include ethyl alcohol, tetrahydrofuran, n-hexane, carbon tetrachloride, methyl ethyl ketone, benzene, ethyl ether, and petroleum ether. These may be used alone or in combination.

  Polyurea resins and polyurethane resins used for forming the shell layer are formed by reacting an isocyanate-derived component (isocyanate component) with an amine-derived component (amine component) or an alcohol-derived component (alcohol component). Is.

  Specific examples of amine components include ethylenediamine, hexamethylenediamine, diaminocyclohexane, piperazine, diethylenetriamine, triethylenetetramine, tetraethylenepentammine, iminobispropylamine, diaminoethyl ether, 1,4-diaminobutane, pentamethylene. Aliphatic amines such as diamine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2-hydroxytrimethylenediamine, diethylaminopropylamine, diaminopropylamine, diaminopropane, 2-methylpentamethylenediamine, xylenediamine, m- Phenylenediamine, triaminobenzene, 3,5-tolylenediamine, diaminodiphenylamine, diaminonaphthalene, t-butyltoluenediamine, diethyltoluene Njiamin, diaminophenol, and the like. Among them, aromatic amines such as phenylenediamine, diaminophenol, and triaminobenzene are exemplified.

In addition, an amine-generating substance that reacts with water and generates an amine component that can react with the isocyanate component as listed above can also be used. In this case, when the toner is produced by the second production method, the amine-generating substance can be mixed with the oily component in advance instead of adding the amine component to the emulsion. As a result, when the oily component is dispersed in the aqueous solvent and emulsified, the amine-forming substance reacts with water to produce an amine component capable of reacting with the isocyanate component, and interfacial polymerization can be performed.
Specific examples of such amine-generating substances include ketimine compounds, trimethylsilyl isocyanate, trimethylsilyl isothiocyanate, triethylsilyl isocyanate, triethylsilyl isothiocyanate, triphenylsilyl isocyanate, and triphenylsilyl isothiocyanate. It is done.
Such amine-generating substances and amine components may be used alone or in combination.

Specific examples of the alcohol component include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, catechol, resorcinol, and hydroquinone. And polyols having two or more hydroxyl groups.
These alcohol components may be used alone or in combination. Moreover, you may mix and use an alcohol component and an amine component.

  Specific examples of the isocyanate component include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 3,3. '-Dimethyldiphenyl-4,4'-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, transcyclohexane 1,4-diisocyanate, diphenyl ether diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, 2,6-diisocyanate caproic acid, tetramethyl-m-xylylene diisocyanate , Tetramethyl-p-xylylene diisocyanate, trimethylhexamethylene diisocyanate, triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, isocyanate alkyl 2,6-diisocyanate capronate, 1,6,11-undecane triisocyanate 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate and the like.

Further, a urethane-modified product using an isocyanate component and a monomer polyol as listed above, an adduct of the isocyanate component and trimethylolpropane as listed above, an isocyanate component and a polysiloxane as listed above Urethane prepolymers using ether polyols or polyester polyols, uretidione-modified products, isocyanurate-modified products, carbodiimide-modified products, uretonimine-modified products, allophanate-modified products, and burette-modified products can also be used as isocyanate components.
These isocyanate components may be used alone or in combination.

-External additives / Surface treatment / Various physical properties of toner-
The volume average particle size of the toner of the present invention is preferably in the range of 4 to 10 μm, particularly 5 to 9 μm.
In addition, a chargeable substance can be attached to the surface of the toner of the present invention. As a chargeable substance, a polymerizable monomer containing a functional group such as amino group, imidazole group, pyridine, piperazine as positive chargeability, halogen atom, nitro group, cyano group, sulfonic acid group, carboxyl group as negative chargeability Further, a known polymer such as a polymer composed of a polymerizable monomer containing a functional group such as a carboxylic acid ester or a phosphoric acid group, or fine particles having the functional group on the surface can be used.
As a method for attaching the chargeable substance to the surface of the toner, known methods such as a graft polymerization method, a phase separation method, a dry mixing method, and a wet mixing method can be used. Among them, the graft polymerization method is preferable from the viewpoint of durability and uniformity.

In addition, lubricant particles can be externally added to the toner of the present invention. As the lubricant particles, known lubricant particles can be used, and specifically, one kind or two or more kinds selected from fatty acids, fatty acid metal salts, aliphatic alcohols, aliphatic amides, aliphatic bisamides, and fatty acid esters. A mixture of
Examples of fatty acids include lauric acid, myristic acid, stearic acid, oleic acid, linoleic acid, ricinoleic acid, arachidic acid, behenic acid, lignoceric acid, ceracoleic acid, and the like, and mixtures thereof.
As fatty acid metal salts, metal salts such as zinc stearate, cadmium, barium, lead, iron, nickel, cobalt, copper, aluminum, magnesium, dibasic lead stearate, zinc oleate, magnesium, iron, cobalt Metal salts such as copper, lead and calcium, metal salts such as palmitic acid and aluminum, calcium, lead caprylate, lead caproate, zinc linoleate, cobalt linoleate, calcium ricinoleate, ricinoleic acid and zinc, cadmium, etc. Examples thereof include metal salts and mixtures thereof.

The aliphatic alcohol may be a monohydric alcohol or a polyhydric alcohol. Typical examples thereof include lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, aralkyl alcohol, and behenyl alcohol.
As fatty acid amides, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide, behenic acid amide, oleic acid amide, linoleic acid amide, linolenic acid amide, cadrenic acid amide, erucic acid amide, ceracolein An acid amide etc. can be mentioned.
Examples of fatty acid bisamides include bislauric acid amide, bismyristic acid amide, bispalmitic acid amide, and bisstearic acid amide. Examples of fatty acid esters include esters of fatty acids and monohydric alcohols, esters of fatty acids and polyhydric alcohols, and partial esters of fatty acids and polyhydric alcohols.

Any known method can be used to add the lubricant particles to the toner. The slurry may be mixed and dried, or may be mixed as a dry powder. Moreover, you may dry, spraying a slurry on dry powder. In order to mix the lubricant particles as a dry powder, it is necessary to dry in advance.
As the dryer, there are known aeration drying apparatus, spray drying apparatus, rotary drying apparatus, airflow drying apparatus, fluidized bed drying apparatus, heat transfer heating type drying apparatus, freeze drying apparatus and the like, and any of them can be used. Various types of rotary container type mixers, fixed container type mixers, and composite type mixers thereof are known for solid mixing, and any of them can be used.

Further, in order to give fluidity and the like to the toner of the present invention, fine particles such as metal oxides such as silicon oxide and aluminum oxide, metal salts, ceramics, resins, and carbon black may be externally added.
As a method for adding these fine particles, the toner particles and fine particles may be attached to the toner surface in a dry manner using a mixer such as a V blender or a Henschel mixer, or the fine particles may be added to water or water / alcohol such as alcohol / water. After being dispersed in this liquid, it may be added to the toner in a slurry state and dried to allow an external additive to adhere to the toner surface.

<Electrophotographic developer>
The electrophotographic toner of the present invention is used as it is as a one-component developer or as a two-component developer. When used as a two-component developer, it is used by mixing with a carrier.
There is no restriction | limiting in particular as a carrier which can be used for a two-component developer, A well-known carrier can be used. Examples thereof include magnetic metals such as iron oxide, nickel and cobalt, magnetic oxides such as ferrite and magnetite, resin-coated carriers having a resin coating layer on the surface of the core material, and magnetic dispersion carriers. 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 a coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the carrier core material, and the carrier core material is fluidized air. And a kneader coater method in which the core material of the carrier and the coating layer forming solution are mixed in a kneader coater and the solvent is removed in a kneader coater.

  The mixing ratio (weight ratio) of the toner of the present invention and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and about 3: 100 to 20: 100. A range is more preferred.

<Image forming method>
The image forming method of the present invention is not particularly limited as long as it uses the toner of the present invention. Specifically, the latent image forming step of forming an electrostatic latent image on the surface of the latent image carrier, and the latent image A developing step of developing the electrostatic latent image formed on the surface of the carrier with the developer containing the toner of the present invention to form a toner image, and the toner image formed on the surface of the latent image carrier on the surface of the recording medium It is particularly preferable that the image forming method includes a transfer step of transferring and a fixing step of thermally fixing the toner image transferred to the surface of the recording medium.

The developer may be either a one-component system or a two-component system. As each of the above steps, a known step in the image forming method can be used. The image forming method of the present invention may include steps other than the steps described above.
For example, the transfer step includes a primary transfer step of transferring a toner image formed on the surface of the latent image carrier to an intermediate transfer member, and a secondary transfer step of transferring the toner image transferred onto the intermediate transfer member to a recording medium. It may consist of.

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

(Synthesis of crystalline polyester resin)
In a 5 L flask, 1800 g (8.9 mol) of sebacic acid, 1073 g (9.08 mol) of 1,6-hexanediol, 53.8 g (0.18 mol) of sodium dimethyl 5-sulfonate, 0.1% dibutyltin oxide .13 g was reacted at 180 ° C. for 5 hours under a nitrogen atmosphere, followed by a condensation reaction at 220 ° C. under reduced pressure.
During the reaction, the obtained polymer was sampled, and the reaction was stopped when the molecular weight reached Mw (weight average molecular weight) = 25400 and Mn (number average molecular weight) = 8500 by GPC (gel permeation chromatography). A crystalline polyester resin was obtained. Melting point (peak temperature measured by DSC) was 70 ° C.

(Preparation of pigment dispersion)
C. I. Pigment Blue 15: 3 18 parts by weight, ethyl acetate 80 parts by weight, solvent-removed Disparon DA-725 (polyester acid amide amine salt, manufactured by Enomoto Kasei Co., Ltd.) 4 parts by weight, and Solsperse 5000 (pigment derivative, GENECA) 1 part by weight was dissolved / dispersed using a sand mill to prepare a pigment dispersion.

(Preparation of release agent dispersion)
As a release agent, 28 parts by weight of polyethylene wax (melting point: 106 ° C.) and 280 parts by weight of ethyl acetate were wet pulverized in a state cooled to 10 ° C. using a DCP mill to prepare a release agent dispersion.

-Production of toner particles-
Example 1
A mixture of 68 g of ethyl acetate, 32.6 g of pigment dispersion, and 29 g of release agent dispersion was mixed with 100 g of crystalline polyester resin and 5 g of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., R972, volume average particle size 16 nm). Heated to dissolve and disperse. Subsequently, 4 g of isocyanate (Takenate D110N; manufactured by Takeda Pharmaceutical Co., Ltd.) was added to 200 g of this dispersion, and a sufficiently mixed solution was obtained (hereinafter, this solution is referred to as A1 solution).
On the other hand, a solution in which 18 g of carboxymethyl cellulose (Serogen B-SH: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved in 282 g of ion-exchanged water was prepared (hereinafter, this solution is referred to as B1 solution).

  Next, emulsification was performed by slowly charging the A1 solution into the A1 solution while stirring the B1 solution with an emulsifier (auto homomixer: manufactured by Tokushu Kika Kogyo Co., Ltd.). Subsequently, the mixed solution obtained by adding the A1 liquid to the B1 liquid was stirred at 400 rpm with a stirrer (three-one motor: manufactured by Shinto Kagaku Co., Ltd.) equipped with a propeller-type stirring blade instead of the emulsifier. . In this state, 30 g of a 5% diethylenetriamine aqueous solution was dropped into the emulsion obtained by stirring for 10 minutes. After completion of the dropping, the reaction was continued at 60 ° C. for 3 hours to obtain a suspension in which toner particles were dispersed.

125 g of ion-exchanged water is added to 125 g of the resulting toner particle suspension (corresponding to 50 g of toner particles), and 200 rotations / cycle by a stirrer (three-one motor: manufactured by Shinto Kagaku Co., Ltd.) equipped with a propeller type stirring blade Stir in minutes. After adding 5 g of 1N nitric acid and 4 g of 10% cerium sulfate aqueous solution to this, 0.5 g of ethylene glycol dimethacrylate was added and reacted at 15 ° C. for 3 hours.
After completion of the reaction, the reaction product was washed with ion exchange water. In this way, toner particles in which ethylene glycol dimethacrylate was graft-polymerized on the surface of the toner particles were obtained. This was again resuspended in ion-exchanged water, and stirred at 200 rpm with a stirrer (three-one motor: manufactured by Shinto Kagaku Co., Ltd.) equipped with a propeller-type stirring blade. Next, 0.4 g of potassium persulfate, 2 g of sodium methallyl sulfonate, and 0.16 g of sodium hydrogen sulfite were sequentially added thereto, and reacted at 25 ° C. for 3 hours.

After completion of the reaction, the toner particles were washed with ion exchange water. The obtained suspension in which the toner particles were dispersed was poured into a stainless steel vat, dried at 40 ° C. for 17 hours with a dryer (manufactured by Yamato Scientific Co., Ltd.), and classified to obtain a toner having an average particle diameter of 7 μm. Next, 1 part by weight of hydrophobic silica (R972: manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts by weight of the toner and mixed well.
Using the toner thus obtained, the minimum fixing temperature, filming, blocking resistance, and fogging were evaluated with a modified machine of A-color 935 (Fuji Xerox Co., Ltd.). The results are shown in Table 1.

(Example 2)
Add 100 g of crystalline polyester resin to a mixed solution of 68 g of ethyl acetate, 32.6 g of pigment dispersion, 29 g of release agent dispersion, 10 g of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., RX50, volume average particle size 40 nm), and heat. Dissolve and disperse. Add 200 g of this dispersion (Takenate D110N; Takeda Pharmaceutical Co., Ltd.) and 3.5 g of methylsilyl triisocyanate (manufactured by Matsumoto Kosho Co., Ltd., ORGATIX SI-310). The mixed solution (A2 liquid) was used in place of the A1 liquid used in Example 1, and the diethylenetriamine was not added dropwise to the emulsion obtained by adding the A2 liquid to the B1 liquid. A toner was prepared in the same manner as in Example 1. The results evaluated in the same manner as in Example 1 are shown in Table 1.

(Example 3)
A toner was prepared in the same manner as in Example 1 except that a mixed solution consisting of 2.25 g of resorcin, 0.1 g of triethylenediamine and 27.65 g of water was used instead of 30 g of the 5% diethylenetriamine aqueous solution. The evaluation results are shown in Table 1.

(Comparative Example 1)
A1 solution used in Example 1 was prepared by adding 100 g of crystalline polyester resin to a mixed solution of 68 g of ethyl acetate, 32.6 g of pigment dispersion, and 29 g of the release agent dispersion, and dissolving / dispersing by heating. This was used in place of the liquid, and the emulsion obtained by adding the C1 liquid to the B1 liquid was added dropwise to 3 L of methanol without adding diethylenetriamine dropwise, and then sufficiently stirred, and then washed with ion-exchanged water. A toner was produced in the same manner as in Example 1. The results evaluated in the same manner as in Example 1 are shown in Table 1.

(Comparative Example 2)
A toner was prepared in the same manner as in Example 1 except that hydrophobic silica was not used. The results evaluated in the same manner as in Example 1 are shown in Table 1.

(Comparative Example 3)
A toner was prepared in the same manner as in Example 3 except that hydrophobic silica was not used. The results evaluated in the same manner as in Example 1 are shown in Table 1.

Various evaluation methods and evaluation criteria shown in Table 1 are as follows.
-Evaluation of minimum fixing temperature-
Using the obtained toner, a solid image was formed on a copy paper (J paper) manufactured by Fuji Xerox with a modified A-color 935 (Fuji Xerox Co., Ltd.) so that the toner amount was 0.9 mg / cm ^2. Formed and evaluated for fixability.
When forming the image, the temperature of the fixing device is changed every 80 ° C. from 80 ° C. to 150 ° C., and a solid image is produced at each fixing temperature. Then, the image surface of each obtained solid image is folded. The degree of peeling of the image of the fold portion was observed. At this time, the fixing temperature at which the width at which the image at the crease peeled was 0.5 mm or less was defined as the minimum fixing temperature.

-Filming evaluation-
Filming on the surface of the photoreceptor after copying 1,000 sheets with a modified machine of A-color 935 (Fuji Xerox Co., Ltd.) was visually observed and evaluated according to the following criteria.
○: Filming is not seen.
X: Filming is observed.

-Evaluation of blocking property-
The obtained toner was placed in an oven at 50 ° C. for 24 hours, and then the presence or absence and the degree of occurrence of aggregates were visually confirmed and evaluated according to the following criteria.
○: Aggregates are not observed.
X: Aggregates are observed.

-Evaluation of fogging-
Similar to the filming evaluation, the image quality (fogging) after 1000 copies were made with a modified machine of A-color 935 (Fuji Xerox Co., Ltd.) was visually observed and evaluated according to the following criteria.
○: Good image quality without fogging.
X: The fog can be visually confirmed.

Claims (6)

In an electrophotographic toner comprising a core layer containing a crystalline resin and a shell layer covering the core layer,
The toner for electrophotography, wherein the core layer contains inorganic particles, and the shell layer contains polyurea and / or polyurethane resin.   The method for producing an electrophotographic toner according to claim 1, wherein the toner is produced using interfacial polymerization. The toner for electrophotography according to claim 1,
A step of preparing an emulsion by dispersing an oily component containing at least the crystalline resin, the inorganic particles, and an isocyanate component in an aqueous solvent;
The method for producing an electrophotographic toner according to claim 2, wherein the toner is produced through a step of interfacial polymerization by adding an amine component and / or an alcohol component to the emulsion.   An oily component containing at least an amine-forming substance that generates an amine component by reacting with the crystalline resin, the inorganic particles, an isocyanate component, and an aqueous solvent is dispersed in the aqueous solvent to perform interfacial polymerization simultaneously with emulsification. The method for producing an electrophotographic toner according to claim 2, wherein the toner is produced through a process.   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 carrier, and a developing step for developing the electrostatic latent image formed on the surface of the latent image carrier with a developer containing toner to form a toner image. And a transfer step of transferring the toner image formed on the surface of the latent image carrier to the surface of the recording medium, and a fixing step of thermally fixing the toner image transferred to the surface of the recording medium.
The image forming method according to claim 1, wherein the toner is an electrophotographic toner according to claim 1.