JP2006268040A - Toner for electrophotography and developer for electrophotography, as well as image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner for electrophotography and a developer for electrophotography which achieve low temperature fixing, have preferable charging property and are hardly deformed in a developing machine, and to provide an image forming method. <P>SOLUTION: The toner for electrophotography contains a binder resin and a coloring agent is characterized in that: the binder resin contains a crystalline polyester resin and a low-molecular weight compound having at least one of a naphthalene skeleton and a biphenyl skeleton; and the crystalline polyester resin contains 0.5 to 30 construction mole% of an aromatic dicarboxylic acid-derived constitutional component. Further, a developer for electrophotography and an image forming method using the toner for electrophotography are disclosed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic toner and an electrophotographic developer that can be used in an electrophotographic apparatus using an electrophotographic process such as a copying machine, a printer, and a facsimile, and an image forming method.

  A number of methods are already 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 photoconductor (latent image holding body) using a photoconductive substance, and the formed latent image is transferred to an electrophotographic toner (hereinafter referred to as “electrophotographic toner”). The toner image on the surface of the photoreceptor is transferred to the surface of a recording medium such as paper with or without an intermediate transfer body. Then, a fixed image is formed through a plurality of steps of fixing the transferred image by heating, pressing, heating and pressing, solvent vapor, or the like. The toner remaining on the surface of the photoreceptor is cleaned by various methods as necessary, and is again subjected to the above-described plurality of steps.

  As a fixing technique for fixing the transferred image transferred to the surface of the recording material, a hot roll fixing is performed by inserting the transferred material on which the toner image is transferred between a pair of rolls including a heating roll and a pressure roll and fixing the transferred image. The law is common. In addition, as the same type of technology, one in which one or both of the rolls are replaced with a belt is also known. These techniques can obtain a fast and robust fixed image compared to other fixing methods, have high energy efficiency, and are less harmful to the environment due to volatilization of solvents and the like.

  On the other hand, in order to reduce the energy consumption of copying machines and printers, a technique for fixing toner with lower energy is desired. Therefore, there is a strong demand for an electrophotographic toner that can be fixed at a lower temperature.

  As a means for lowering the toner fixing temperature, a technique for lowering the glass transition point of a toner resin (binder resin) is generally performed. However, if the glass transition point is too low, powder aggregation is likely to occur (blocking), and the storage stability of the toner on the surface of the fixed image is lost, so 50 ° C. is practically the lower limit. This glass transition point is a design point of many resin for toners currently on the market, and the method of lowering the glass transition point has a problem that it is impossible to obtain a toner that can be fixed at a lower temperature than ever. Although the fixing temperature can be lowered by using a plasticizer, there is a problem because blocking occurs during storage of the toner or in the developing device.

  As a means for achieving both blocking prevention, image storability up to 60 ° C., and low-temperature fixability, a technique using a crystalline resin as a binder resin constituting the toner can be considered. For example, a method using a crystalline resin as a toner has been known for a long time (see, for example, Patent Document 2). In addition, for the purpose of preventing offset, fixing pressure, and the like, a technique using a crystalline resin has been known for a long time (see, for example, Patent Documents 3 and 4).

  However, the above disclosed technique applies, for example, a polymer having an alkyl group side chain having 14 or more carbon atoms to the toner, and has a melting point of 62 to 66 ° C., which is too low. There was a problem with reliability. In addition, even when other crystalline resins are used, there is a problem that the fixing performance to paper is not sufficient.

  A polyester resin is an example of a crystalline resin that is expected to improve the fixability to paper. As a technique using a crystalline polyester resin for a toner, a technique using a mixture of an amorphous polyester resin having a glass transition temperature of 40 ° C. or higher and a crystalline polyester resin having a melting point of 130 to 200 ° C. has been proposed (for example, , See Patent Document 5). However, this technique has excellent pulverization properties and blocking resistance, but has a problem in that the low-temperature fixability cannot be achieved since the crystalline polyester resin has a high melting point.

  In order to solve the above problem, a technique using a toner in which a crystalline resin having a melting point of 110 ° C. or less and a non-crystalline resin is mixed has been proposed (for example, see Patent Document 6). However, when an amorphous resin is mixed with a crystalline resin, there are practical problems such as a drop in the melting point of the toner, toner blocking, and deterioration in image storage stability. In addition, when the amount of the amorphous resin component is large, the characteristics of the amorphous resin component are largely reflected, so that it is difficult to lower the fixing temperature than the conventional one. For this reason, if a crystalline resin is used singly as a resin for toner, or if a non-crystalline resin is mixed, it is difficult to put it to practical use.

  From the above, it is desirable to use the crystalline polyester resin alone for hot roll fixing as much as possible, and several examples using the crystalline polyester resin have been proposed (see, for example, Patent Documents 7 to 9). However, in these techniques, the crystalline polyester resin is a resin using alkylene glycol or alicyclic alcohol having a small number of carbon atoms with respect to the carboxylic acid component of terephthalic acid.

  Although these polyester resins are described as crystalline polyester resins in the above document, they are substantially partially crystalline polyester resins, so the viscosity change with respect to the temperature of the toner (resin) is not steep, and the blocking property / Although there is no problem in image storability, low temperature fixing could not be realized in heat roll fixing.

  On the other hand, the present inventors have shown that a toner containing a crystalline polyester resin having a crosslinked structure as a main component has excellent blocking resistance and image storage stability and can realize low-temperature fixing (for example, Patent Documents). 10). However, in such a toner, further improvement in chargeability is desired particularly in the two-component charging with a carrier.

  Therefore, the ester concentration of the crystalline polyester resin includes, as a main component, a crystalline polyester resin in which the ester concentration M defined by the following formula (1) is 0.01 or more and 0.12 or less in the binder resin. It has been shown that an electrophotographic toner characterized by the above can be realized as a toner with further improved chargeability (see, for example, Patent Document 11).

M = K / A Formula (1)
(In the above formula (1), M represents the ester concentration, K represents the number of ester groups in the polymer, and A represents the number of atoms constituting the polymer chain of the polymer.)

  On the other hand, in the same specification, the ester concentration M is 0.01 or more and 0.12 or less, and 2 to 20 mol% of a divalent or higher carboxylic acid having a sulfonic acid group is contained as a copolymerization component. A method for producing a toner for electrophotography, characterized in that a crystalline polyester resin is emulsified and further aggregated and fused to adjust the toner diameter. In this case, a polyester self-emulsified solution can be prepared, and the toner obtained by the aggregation and coalescence has a narrow particle size distribution and good transferability.

  However, it has been found that a toner produced by an aggregation coalescence method using a crystalline resin copolymerized with a carboxylic acid having a sulfone group has low chargeability under high temperature and high humidity. The chargeability can be adjusted by using an external additive. However, it is preferable that the chargeability is good even in a non-externally added toner state. The discovery of a new composition of a crystalline polyester resin that is capable of being charged at high temperature and high humidity while being capable of low-temperature fixing, and that can be applied with an aggregation coalescence method is desired. As the derived constituent component, two or more kinds of constituent components derived from dicarboxylic acid are included, and among the constituent components derived from all acids, the aromatic dicarboxylic acid-derived constituent component content is 0.5 to 30. In the range of constituent mol%, and when a dicarboxylic acid-derived constituent component having a sulfonic acid group is included, the dicarboxylic acid-derived constituent component content having the sulfonic acid group among all the acid-derived constituent components is A crystalline polyester resin characterized by 5 mol% or less was proposed (see, for example, Patent Document 12).

However, the toner using this resin has a disadvantage that it is easily crushed. When the toner remains on the photosensitive member, it deforms without being able to withstand the force received between the cleaning blade and the intermediate transfer drum, and the like. Will remain. As a result, filming on the photosensitive member or the intermediate transfer member is promoted.
Japanese Patent Publication No.42-23910 Japanese Patent Publication No. 56-13943 Japanese Examined Patent Publication No.62-39428 Japanese Patent Publication No. 63-25335 Japanese Examined Patent Publication No.62-39428 Japanese Patent Publication No. 4-30014 Japanese Patent Laid-Open No. 4-120554 JP-A-4-239021 JP-A-5-165252 JP 2001-117268 A JP 2002-82845 A JP 2004-168827 A

  The object of the present invention is to solve the above-mentioned problems of the prior art. That is, an object of the present invention is to provide an electrophotographic toner and an electrophotographic developer, and an image forming method that achieve low-temperature fixing, have good chargeability, and are not easily deformed in a developing machine. .

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1> An electrophotographic toner containing a binder resin and a colorant, wherein the binder resin includes a crystalline polyester resin and a low molecular compound having at least one of a naphthalene skeleton and a biphenyl skeleton, The toner for electrophotography, wherein the crystalline polyester resin contains 0.5 to 30 constituent mol% of an aromatic dicarboxylic acid-derived constituent component.

<2> An electrophotographic developer comprising an electrophotographic toner and a carrier, wherein the electrophotographic toner is the electrophotographic toner of the present invention. .

<3>
A latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, a developing step of developing the electrostatic latent image with a developer to form a toner image, and a toner formed on the surface of the latent image holding member An image forming method comprising: a transfer step of transferring an image to a recording material to form a transfer image; and a fixing step of fixing the transfer image transferred to the recording material, wherein the developer is the above-mentioned invention. And an image forming method comprising the toner for electrophotography.

  The image forming method of the present invention preferably further includes a cleaning step, and the cleaning process in the cleaning step removes the toner remaining on the surface of the photoreceptor after the development step and the transfer step. It is a process, and it is preferable to satisfy any of the following conditions (1) to (3).

(1) The thickness of the conductive substrate of the photoreceptor is 1.4 mm or more and 2.2 mm or less.
(2) The cleaning means in the cleaning process is held by a support member and has an elastic blade that is in contact with the surface of the photosensitive member with a contact pressure of 20 g / cm to 40 g / cm. .
(3) The contact angle of the elastic blade is 9 ° or more and 17 ° or less.

  According to the present invention, it is possible to provide an electrophotographic toner, an electrophotographic developer, and an image forming method that achieve low-temperature fixing, have good chargeability, and are not easily deformed in a developing machine.

  Hereinafter, the electrophotographic toner, the electrophotographic developer, and the image forming method of the present invention will be described in detail.

[1] Toner for electrophotography:
The electrophotographic toner of the present invention contains a binder resin and a colorant. The binder resin includes a crystalline polyester resin and a predetermined low molecular compound. Hereinafter, each component of the electrophotographic toner of the present invention will be described.

<Binder resin>
The binder resin in the electrophotographic toner of the present invention contains a crystalline polyester resin as a main component. Here, the “main component” refers to a main component among the components constituting the binder resin, and specifically refers to a component constituting 50% by mass or more of the binder resin. However, in the present invention, among the binder resins, the crystalline polyester resin is preferably 70% by mass or more, and more preferably 80% by mass or more in the binder resin.

(Crystalline polyester resin)
The crystalline polyester resin is a specific polyester resin synthesized from an acid (dicarboxylic acid) component and an alcohol (diol) component. In the following description, in the polyester resin, the component that was an acid component before the synthesis of the polyester resin is referred to as “acid-derived component”, and the component that was the alcohol component before the synthesis of the polyester resin is referred to as “alcohol. "Derived component".

  As described above, the polyester resin is a crystalline polyester resin. When the resin is not crystalline, that is, when it is amorphous, toner blocking resistance and image storage stability cannot be maintained while ensuring good low-temperature fixability.

  In the present invention, the “crystallinity” of the “crystalline polyester resin” refers to having a clear endothermic peak in the differential scanning calorimetry (DSC), not a stepwise endothermic amount change. Further, the endothermic peak may show a peak having a width of 40 to 50 ° C. when the toner is used. In the case of a polymer obtained by copolymerizing other components with the crystalline polyester main chain, if the other components are 50% by mass or less, this copolymer is also called crystalline polyester.

-Acid-derived components-
Examples of the acid for forming the acid-derived constituent component include various dicarboxylic acids, but as the main acid-derived constituent component in the specific polyester resin, an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid are desirable. The dicarboxylic acid is preferably a linear carboxylic acid.

  Moreover, in this invention, it is preferable that crystalline polyester resin contains a 2 or more types of dicarboxylic acid origin structural component as said acid origin structural component. By including two or more kinds of components derived from dicarboxylic acid, for example, the emulsifiability in the emulsion aggregation method described later can be improved.

  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, etc. 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 that is a copolymer component necessary for the present invention include terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid. Among them, terephthalic acid, isophthalic acid, t-butylisophthalic acid, and alkyl esters thereof are preferable because they are easily available and easily form an easily emulsifiable polymer.

  From the viewpoints of emulsification in the emulsion aggregation method and charging stability when a toner is used, it is preferable to include a component derived from an aromatic dicarboxylic acid having no sulfonic acid group as a component of the crystalline polyester resin.

  The crystalline polyester resin (hereinafter sometimes simply referred to as “polyester resin”) contains 0.5 to 30 constituent mol% of an aromatic dicarboxylic acid-derived constituent component. When the content exceeds 30 component mol% of the acid-derived constituent component in the polymer, the crystallinity of the crystalline polyester resin is high, the melting point is high, and the emulsifiability deteriorates. Moreover, even if it is less than 0.5 component mol%, emulsification will deteriorate. Therefore, among all the acid-derived components in the polymer, the aromatic dicarboxylic acid-derived component content needs to be in the range of 0.5 to 30 component mol%. Moreover, it is preferable that the said content is the range of 1-15 component mol%, and it is more preferable that it is the range of 3-10 component mol%.

  The remaining acid-derived constituent components in the polymer are composed of the aliphatic dicarboxylic acid-derived constituent components, except when a dicarboxylic acid-derived component having a sulfonic acid group, which will be described later, is included.

  In the present specification, “constituent mol%” means that the acid-derived constituent component in the entire acid-derived constituent component in the polyester resin or the alcohol constituent component in the entire alcohol-derived constituent component is 1 unit (mol). ) Indicates the percentage.

  Examples of the acid-derived constituent component include the above-mentioned aliphatic dicarboxylic acid (main component) -derived constituent component and aromatic dicarboxylic acid (copolymerization component) -derived constituent component, dicarboxylic acid-derived constituent component having a double bond, and sulfonic acid. A constituent component such as a constituent component derived from a dicarboxylic acid having a group may be contained.

  In addition to the components derived from dicarboxylic acids having a double bond, the components derived from lower alkyl esters or acid anhydrides of dicarboxylic acids having a double bond are included in the components derived from dicarboxylic acids having a double bond. included. Further, the dicarboxylic acid-derived constituent 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 constituent component derived from a dicarboxylic acid having a sulfonic acid group. Components are also included.

  A dicarboxylic acid having a double bond can be suitably used in order to prevent hot offset at the time of fixing since the entire resin can be cross-linked 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 content of these dicarboxylic acid-derived components having double bonds in the total acid-derived components is preferably 20 component mol% or less, and more preferably in the range of 2 to 10 component mol%.

  When the content exceeds 20 component mol%, the crystallinity of the polyester resin is lowered, the melting point is lowered, and the storage stability of the image may be deteriorated.

  A dicarboxylic acid having a sulfonic acid group is effective in that it can favorably disperse a coloring material such as a pigment. Further, when the entire resin is emulsified or suspended in water to produce fine particles, if there are sulfonic acid groups, emulsification or suspension is possible without using a surfactant, as will be described later. Examples of the dicarboxylic acid having a sulfonic acid 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 from the viewpoint of cost.

  When the dicarboxylic acid-derived constituent component having a sulfonic acid group is contained in the polymer, the dicarboxylic acid-derived constituent component content having the sulfonic acid group in the total acid-derived constituent component is 5 constituent mol% or less. It is necessary to be. Moreover, the said content can be used in 3 mol% or less of range.

  When the content exceeds 5 component mol%, the hydrophilicity of the polyester resin increases, and the chargeability of the toner under high humidity deteriorates. Although it is not always necessary to use it as a copolymerization component, it is desirable to use it in order to assist emulsification of the resin.

-Alcohol-derived components-
As alcohol for becoming a component derived from alcohol, aliphatic diol is preferable, and 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 toner blocking resistance, image storage stability, and 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 fixing at low temperature may be difficult. Tends to be difficult. 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, ethylene glycol, 1,4-butanediol, 1,6-henquinsandiol, 1,9-nonanediol, and 1,10-decanediol are preferable in view of availability.

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

  If 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 toner blocking resistance, image storage stability, and low-temperature fixability are deteriorated. May end up.

  Other components included as necessary include a diol-derived component having a double bond and a diol-derived component having a sulfonic acid group. 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.

  The content of these double-bonded diol-derived components in the total acid-derived components is preferably 20 component mol% or less, and more preferably 2 to 10 component mol%. If the content exceeds 20 component mol%, the crystallinity of the polyester resin may be lowered, the melting point may be lowered, and the image storage stability may be deteriorated.

  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 salt. Etc.

  The content of these diol-derived constituent components having a sulfonic acid group in the total acid-derived constituent components is preferably 5 constituent mol% or less, more preferably in the range of 0.5 to 3 constituent mol%, but the minimum requirement Only the amount is enough.

  When the content exceeds 5 component mol%, the hydrophilicity of the crystalline polyester resin increases, and the chargeability of the toner under high humidity deteriorates. If it is not necessary, it is not necessary to use it as a copolymerization component, but it is preferable to use the minimum amount necessary to aid emulsification of the resin. About the usage-amount, it is necessary to adjust the amount to the minimum especially with the dicarboxylic acid component which has the above-mentioned sulfonic acid group. In addition, if the above-mentioned dicarboxylic acid component having a sulfonic acid group is used as an acid component, the diol having a sulfonic acid group does not need to be basically used.

  When adding an alcohol-derived component other than these aliphatic diol-derived components (a diol-derived component having a double bond and a diol-derived component having a sulfonic acid group), the content of these alcohol-derived components is The range of 1-20 constituent mol% is preferable, and the range of 2-10 constituent mol% is more preferable.

  As melting | fusing point of crystalline polyester resin, it is preferable that it is the range of 60-120 degreeC, and it is more preferable that it is the range of 70-100 degreeC. If the melting point is less than 60 ° C., powder aggregation tends to occur and the storability of the fixed image may be deteriorated. On the other hand, if it exceeds 120 ° C., low-temperature fixing may not be possible.

  In the present invention, the melting point of the crystalline polyester resin is measured using a differential scanning calorimeter (DSC), and the endothermic peak when measured at a heating rate of 10 ° C. per minute from room temperature to 150 ° C. The top value was used.

  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. For example, direct polycondensation, transesterification method, etc. Depending on the type, it will be manufactured separately. The molar ratio (acid component / alcohol component) when the acid component and the alcohol component are reacted 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 is preferably 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 exists in the copolymerization reaction, it is preferable to condense the monomer having poor compatibility with the monomer and the acid or alcohol to be polycondensed in advance, and then polycondense 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. A compound, a phosphorous acid compound, a phosphoric acid compound, an amine compound, etc. are mentioned, Specifically, the following compounds are mentioned.

  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.

(Low molecular compound)
Another important component of the present invention is a low-molecular compound having a naphthalene skeleton or a biphenyl skeleton. By containing the low molecular weight compound, the hardness of the electrophotographic toner is improved and the toner becomes difficult to be deformed, and the charging property can be improved. This is presumably because the low molecular weight compound enters the amorphous part of the crystalline polyester resin and suppresses the movement of molecules in the part. As a result, the hardness of the entire electrophotographic toner is improved, and it is considered that the chargeability is improved by the movement of molecules.

  Examples of the low molecular weight compound having a biphenyl skeleton include biphenyl, 4-biphenylacetic acid, 4-biphenylcarbonitrile, 2-biphenylcarboxylic acid, 4-biphenylcarboxylic acid, 4,4′-biphenyldicarboxylic acid, and methyl esters thereof And lower alkyl esters. Any compound can be used as long as it has a biphenyl skeleton and a melting point of 70 ° C. or higher. However, 4-biphenylacetic acid, 4-biphenylcarboxylic acid, 4,4′biphenyldicarboxylic acid, and methyl esters thereof (for example, , 4,4′dimethyl biphenyldicarboxylate).

  The low molecular weight compound having a naphthalene skeleton may be any compound having a naphthalene skeleton having a melting point of 70 ° C. or higher, such as naphthalene, naphthalene acetic acid, 2,6-naphthalenedicarboxylic acid, 1-naphthalene sulfonic acid, etc. Naphthalene acetic acid, 2,6-naphthalenedicarboxylic acid and its methyl ester (dimethyl 2,6-naphthalenedicarboxylate) are preferable from the viewpoint of possible.

  Most preferred examples of the low molecular weight compound having a naphthalene skeleton or a biphenyl skeleton are compounds represented by the following general formulas (1) to (3) from the viewpoint that compatibility with a resin is important.

In the general formulas (1) to (3), R ¹ and R ² are each independently a substituent represented by “—COOR ³ ”, “—CH ₂ COOR ⁴ ” or “—CONHR ⁵ ”. It is preferable. R ³ , R ⁴ and R ⁵ are preferably each independently hydrogen or an alkyl group of C _{1 to} C ₁₂ .

  Such low molecular weight compounds can be used in combination of not only one type but also two or more types. The content of the low molecular weight compound (when used in combination of two or more) is preferably 1 to 12 parts by mass, preferably 3 to 10 parts by mass with respect to 100 parts by mass of the crystalline polyester resin. Is more preferable, and it is more preferable to set it as 5-8 mass parts. If the amount is less than 1 part by mass, the hardness of the resin does not increase, and the resin may be easily deformed. Furthermore, even if it exceeds 12 parts by mass, the hardness does not increase and may be easily deformed. It is important that an appropriate amount such as the above range is well dispersed in the resin.

<Colorant>
There is no restriction | limiting in particular as a coloring agent in the toner for electrophotography of this invention, A well-known coloring agent is mentioned, It can select suitably according to the objective. 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. Specific examples of the colorant include carbon blacks such as furnace black, channel black, acetylene black, and thermal black; inorganic pigments such as bengara, aniline black, bitumen, titanium oxide, and magnetic powder; fast yellow, monoazo Azo pigments such as yellow, disazo yellow, pyrazolone red, chelate red, brilliant carmine (3B, 6B, etc.), para brown, etc .; phthalocyanine pigments such as copper phthalocyanine, metal-free phthalocyanine; flavantron yellow, dibromoanthrone orange, perylene red, quinacridone And condensed polycyclic pigments such as red and dioxazine violet.

  Chrome Yellow, Hansa Yellow, Benzidine Yellow, Slen Yellow, Quinoline Yellow, Permanent Orange GTR, Pyrazolone Orange, Vulcan Orange, Watch Young Red, Permanent Red, Dupont Oil Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Various pigments such as Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, Para Brown; Acridine, Xanthene, Azo, Benzoquinone, Azine, Anthraquinone, dioxazine, thiazine, azomethine, indigo, thioindigo, phthalocyanine, aniline black , Polymethine dyes, triphenylmethane dyes, diphenylmethane dyes, thiazole type, various dyes such as xanthene; and the like. You may mix black pigments, such as carbon black, and dye to such an extent that transparency is not reduced to these colorants. Moreover, a disperse dye, an oil-soluble dye, etc. are mentioned.

  The content of the colorant in the electrophotographic toner of the present invention is preferably in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the binder resin, but within a range that does not impair the smoothness of the image surface after fixing. Of these numerical ranges, as many as possible are 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, each color toner such as yellow toner, magenta toner, cyan toner, and black toner can be obtained by appropriately selecting the type of the colorant.

<Other ingredients>
The other components that can be used in the electrophotographic toner of the present invention are not particularly limited and may be appropriately selected depending on the purpose. For example, various known components such as inorganic fine particles, organic fine particles, charge control agents, release agents, etc. An additive 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 in the range of 1 to 1000 nm, and the addition amount (external addition) is 0.01 to 20 parts by mass with respect to 100 parts by mass of the toner. The range of is preferable.

  Organic fine particles are generally used for the purpose of improving cleaning properties, transfer properties, and sometimes charging properties. Examples of the organic fine particles include fine particles such as polystyrene, polymethyl methacrylate, polyvinylidene fluoride, and polystyrene-acrylic copolymer.

  The charge control agent is generally used for the purpose of improving the chargeability. Examples of the charge control agent include salicylic acid metal salts, metal-containing azo compounds, nigrosine and quaternary ammonium salts.

  A mold release agent is generally used for the purpose of improving mold 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; minerals such as montan wax, ozokerite, ceresin wax, microcrystalline wax, Fischer-Tropsch wax -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 in the range of 0.5 to 50% by mass, more preferably in the range of 1 to 30% by mass, and further preferably 5 to 15% by mass with respect to the total amount of toner. % Range. When the addition amount is less than 0.5% by mass, there is no effect of adding a release agent. When the addition amount exceeds 50% by mass, the chargeability is likely to be affected, or the toner is easily destroyed inside the developing device. In addition to the effect that the mold agent is spent on the carrier and the charge is likely to decrease, for example, when color toner is used, the oozing on the image surface during fixing tends to be insufficient, Since the release agent tends to stay in the image, transparency is deteriorated, which is not preferable.

<Other configurations>
The surface of the electrophotographic 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. For example, if the surface layer of non-melting or high melting point covers the toner thickly, the low-temperature fixability due to the use of the crystalline polyester resin cannot be sufficiently exhibited. Therefore, it is desirable that the film thickness of the surface layer is as thin as possible, and specifically, it is preferable to be in the range of 0.001 to 1 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, fine particles thereof, colorant, inorganic fine particles added as necessary, and other materials Are preferably used.

  Examples of components constituting the surface layer include silane coupling agents, isocyanates, vinyl monomers, resins, and fine particles thereof. In addition, a polar group is preferably introduced into the component, and the adhesive force between the toner and a recording medium such as paper increases when chemically bonded.

  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, An ester group, a sulfone group, etc. are mentioned.

  Chemical treatment methods include, for example, a strong oxidizing substance such as peroxide, a method of oxidizing by ozone oxidation, plasma oxidation, etc., a method of bonding a polymerizable monomer containing a polar group by graft polymerization, seed polymerization, etc. Can be mentioned.

  Further, the surface layer may be provided by chemically or physically attaching the above substance to the toner particle surface. For example, the resin fine particles can be coated with the toner on the outside of the toner base particles using a mechanical force, and such a method is suitable for adjusting the charging characteristics of the toner base particles. Examples of the resin fine particles include styrene resin, styrene-acrylic copolymer, and polyester resin. Examples of the mixer used for coating include a sample mill, a Henschel mill, a V blender, and a hybridizer.

  Further, fine particles such as metals, metal oxides, metal salts, ceramics, resins, resin fine particles, and carbon black may be further externally added for the purpose of improving chargeability, conductivity, powder flowability, lubricity, and the like. Good.

  The volume average particle size of the electrophotographic toner of the present invention is preferably in the range of 1 to 20 μm, more preferably in the range of 2 to 8 μm. Moreover, as a number average particle diameter, the range of 1-20 micrometers is preferable, and the range of 2-8 micrometers is more preferable.

  The volume average particle diameter and the number average particle diameter can be determined, for example, by measuring with a 50 μm aperture diameter using a Coulter counter [TA-II] type (manufactured by Beckman Coulter, Inc.). At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton II: manufactured by Beckman-Coulter) and dispersed by ultrasonic waves for 30 seconds or more.

<Preferable Physical Properties of Electrophotographic Toner of the Present Invention>
It is desirable that the toner used in the present invention has sufficient hardness at normal temperature. Specifically, when the dynamic viscoelasticity is an angular frequency of 1 rad / sec, a strain of 0.1%, and a temperature of 30 ° C., the storage elastic modulus GL (30) is 1 × 10 ⁶ Pa or more, and the loss elastic modulus GN ( 30) is preferably 1 × 10 ⁶ Pa or more. The storage elastic modulus GL and the loss elastic modulus GN are stipulated in JIS K-6900.

When the storage elastic modulus GL (30) is less than 1 × 10 ⁶ Pa or the loss elastic modulus GN (30) is less than 1 × 10 ⁶ Pa at an angular frequency of 1 rad / sec and 30 ° C. When mixed with the carrier, the toner particles may be deformed by the pressure or shear force received from the carrier, and stable charge development characteristics may not be maintained. Further, when the toner on the surface of the latent image carrier (photoconductor) is cleaned, the toner may be deformed by a shearing force received from the cleaning blade, resulting in poor cleaning.

  When the storage elastic modulus GL (30) and the loss elastic modulus GN (30) are within the above ranges at an angular frequency of 1 rad / sec and 30 ° C., the characteristics during fixing are stable even when used in a high-speed electrophotographic apparatus. It is preferable.

  The electrophotographic toner of the present invention preferably has a melting point in the temperature range of 60 to 120 ° C. The specific polyester resin rapidly decreases in viscosity at the boundary of the melting point, and thus aggregates and causes blocking when stored at a temperature higher than the melting point. Therefore, the melting point of the electrophotographic toner of the present invention containing the specific polyester resin (crystalline polyester resin) as the main component of the binder resin is higher than the temperature exposed during storage or use, that is, 60 ° C. or more. It is preferable that On the other hand, if the melting point is higher than 120 ° C., it may be difficult to achieve low-temperature fixing. The electrophotographic toner of the present invention preferably has a melting point in the temperature range of 70 to 100 ° C.

  The melting point of the electrophotographic toner of the present invention can be determined as the melting peak temperature of input compensated differential scanning calorimetry as shown in JIS K-7121. A crystalline resin may show a plurality of melting peaks, but in the present invention, the maximum peak is regarded as the melting point.

  Further, the toner according to the present invention has a temperature range in which the fluctuations in the storage elastic modulus GL and the loss elastic modulus GN due to temperature change are two or more digits in the temperature range of 10 ° C. (when the temperature is increased by 10 ° C. Furthermore, it is preferable to have a temperature interval in which the values of GL and GN change to values of 1/100 or less. If the storage elastic modulus GL and the loss elastic modulus GN do not have the temperature section, the fixing temperature becomes high, and as a result, it may be insufficient to reduce the energy consumption of the fixing process.

<Method for producing electrophotographic toner>
The method for producing the electrophotographic toner of the present invention described above is not particularly limited, but the wet granulation method is particularly preferable. As the wet granulation method, known methods such as a melt suspension method, an emulsion aggregation method, and a dissolution suspension method are preferably mentioned. However, since the present invention is useful when using the emulsion aggregation method, the emulsion aggregation method Will be described as an example.

  The emulsion aggregation method includes an emulsification step of emulsifying the specific polyester resin already described in the “Binder resin” section of the “electrophotographic toner” of the present invention to form emulsified particles (droplets); An aggregation step of forming an aggregate of particles (droplets), and a fusion step of fusing the aggregate to cause heat fusion.

-Emulsification process-
In the emulsification step, the emulsified particles (droplets) of the crystalline polyester resin are a mixed liquid (polymer) containing an aqueous medium, the polyester resin, the low molecular compound having the naphthalene skeleton or biphenyl skeleton described above, and a colorant as necessary. Formed by applying a shearing force to the mixed solution. The low molecular weight compound having a naphthalene skeleton or a biphenyl skeleton is previously melt-kneaded in a crystalline resin, or is dissolved and mixed with the crystalline resin using an organic solvent.

  At that time, by heating or dissolving the polyester resin in the organic solvent, the viscosity of the polymer liquid can be lowered to form the emulsified particles, but it is better not to use the organic solvent from the viewpoint of environmental pollution as much as possible. . Moreover, a dispersing agent can also be used for stabilization of emulsified particles and thickening of the aqueous medium. Hereinafter, such a dispersion of emulsified particles may be referred to as a “resin particle dispersion”.

  Examples of the dispersant include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium polymethacrylate, sodium dodecylbenzenesulfonate, sodium octadecylsulfate, and sodium oleate. , Anionic surfactants such as sodium laurate and potassium stearate, cationic surfactants such as laurylamine acetate, stearylamine acetate and lauryltrimethylammonium chloride, zwitterionic surfactants such as lauryldimethylamine oxide, poly Nonoxy such as oxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine, etc. Surfactants such as emissions surfactant, tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, and inorganic compounds such as barium carbonate.

  When an inorganic compound is used as the dispersant, a commercially available product may be used as it is, but for the purpose of obtaining fine particles, a method of producing fine particles of an inorganic compound in the dispersant may be employed. As a usage-amount of a dispersing agent, the range of 0.01-20 mass parts is preferable with respect to 100 mass parts of crystalline polyester resins.

  In the emulsification step, the crystalline polyester resin is copolymerized with a dicarboxylic acid having a sulfonic acid group (that is, a suitable amount of a dicarboxylic acid-derived component having a sulfonic acid group is included in the acid-derived component). ) And a dispersion stabilizer such as a surfactant can be reduced. However, emulsification can be facilitated by increasing the amount of the sulfonic acid group, but the chargeability of the toner, particularly the chargeability under high temperature and high humidity, tends to deteriorate, so that the crystalline polyester resin described above is as much as possible. It is preferable to design the composition with a small amount of sulfonic acid group. If a crystalline polyester resin is used, emulsified particles can be formed without using a dicarboxylic acid having a sulfonic acid group.

  Examples of the organic solvent include ethyl acetate and toluene, which are appropriately selected according to the crystalline polyester resin.

  As the usage-amount of an organic solvent, 50-5000 mass with respect to 100 mass parts of total amounts of crystalline polyester resin and the other monomer used as needed (Hereafter, it may only be called "polymer" collectively.). The range of parts is preferable, and the range of 120 to 1000 parts by mass is more preferable. In addition, a colorant can be mixed before forming the emulsified particles. The colorant used is the same as already described in the section “Colorant” of the electrophotographic toner of the present invention.

  In addition, when using polyester which reduced the amount of sulfone groups, it can emulsify by reducing dispersion stabilizers, such as surfactant, by bringing pH at the time of emulsification to the alkaline side.

  Examples of the emulsifier used when forming the emulsified particles include a homogenizer, a homomixer, a cavitron, a clear mix, a pressure kneader, an extruder, and a media disperser. The size of the emulsified particles (droplets) of the polyester resin is preferably in the range of 0.01 to 1 μm, more preferably in the range of 0.03 to 0.3 μm, in terms of the average particle size (volume average particle size). 0.03-0.4 μm is more preferable.

  As a method for dispersing the colorant, an arbitrary method, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used, and there is no limitation.

  If necessary, an aqueous dispersion of these colorants can be prepared using a surfactant, or an organic solvent dispersion of these colorants can be prepared using a dispersant. Hereinafter, such a colorant dispersion may be referred to as a “colored particle dispersion”. As the surfactant and the dispersing agent used for dispersion, the same dispersing agents that can be used when dispersing the crystalline polyester resin can be used.

  The addition amount of the colorant is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, and more preferably 2 to 10% by mass with respect to the total amount of the polymer. More preferably, it is especially preferable to set it as the range of 2-7 mass%.

  When the colorant is mixed in the emulsification step, the polymer and the colorant can be mixed by mixing the colorant or the organic solvent dispersion of the colorant with the organic solvent solution of the polymer.

-Aggregation process-
In the aggregation step, the obtained emulsified particles are aggregated by heating at a temperature near the melting point of the crystalline polyester resin and at a temperature below the melting point to form an aggregate. Formation of the aggregate of the emulsified particles is performed by acidifying the pH of the emulsion under 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. At this time, it is also effective to use a flocculant.

  As the flocculant to be used, a surfactant having a reverse polarity to 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 metals such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include a salt polymer. Among these, an aluminum salt and a polymer thereof are particularly preferable. 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.

-Fusion process-
In the fusion step, under the same stirring as in the aggregation step, the aggregation suspension is stopped by setting the pH of the suspension of the aggregate to a range of 3 to 10, and heated at a temperature equal to or higher than the melting point of the crystalline polyester resin. To fuse the aggregates.

  There is no problem if the heating temperature is equal to or higher than the melting point of the polyester resin. The heating time may be performed so that the fusion is sufficiently performed, and may be performed for about 0.5 to 10 hours.

  The fused particles obtained by fusing can be made into toner particles through a solid-liquid separation process such as filtration and, if necessary, a washing process and a drying process. In this case, in order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to sufficiently wash in the washing step.

  In the drying process, an arbitrary method such as a normal vibration type fluidized drying method, a spray drying method, a freeze drying method, or a flash jet method can be adopted. It is desirable that the toner particles have a moisture content after drying of 1.0% by mass or less, and preferably 0.5% by mass or less.

  When polyester containing a double bond is used as a copolymerization component, in the emulsification step, the aggregation step, and the fusion step, when the polyester resin is heated to the melting point or higher, or after completion of each step, the polyester resin is heated separately. Then, a crosslinking reaction may be performed. When the crosslinking reaction is performed, for example, an unsaturated crystalline polyester resin obtained by copolymerizing a double bond component as a binder resin is used, and a radical reaction is caused in the resin to introduce a crosslinked structure. At this time, a polymerization initiator shown below may be used.

Examples of the polymerization initiator include t-butyl peroxy-2-ethylhexanoate, cumyl perpivalate, t-butyl peroxylaurate, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, di-t. -Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane 1,1-bis (t-butylperoxy) cyclohexane, 1,4-bis (t-butylperoxycarboni) E) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane,

1,3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, di-t-butyldiperoxyisophthalate, 2,2-bis (4,4-di-t-butylper) Oxycyclohexyl) propane, di-t-butylperoxy-α-methylsuccinate, di-t-butylperoxydimethylglutarate, di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, diethylene glycol-bis (t-butylperoxycarbonate) Di-t-butylperoxytrimethyladipate, tris (t-butylperoxy) triazine, vinyltris (t-butylperoxy) silane, 2,2′-azobis (2-methylpropionamidine dihydrochloride), 2,2 Examples include '-azobis [N- (2-carboxyethyl) -2-methylpropionamidine], 4,4'-azobis (4-cyanovaleric acid) and the like.

  These polymerization initiators can be used alone or in combination of two or more. The amount and type of the polymerization initiator are selected depending on the amount of unsaturated sites in the polymer and the type and amount of the coexisting colorant.

  The polymerization initiator may be mixed with the polymer in advance before the emulsification step, or may be incorporated into the aggregate in the aggregation step. Further, it may be introduced after the fusion step or after the fusion step. In the case of introduction after the aggregation step, the fusion step, or the fusion step, a solution in which the polymerization initiator is dissolved or emulsified is added to a particle dispersion (resin particle dispersion or the like). These polymerization initiators may be added with known crosslinking agents, chain transfer agents, polymerization inhibitors and the like for the purpose of controlling the degree of polymerization.

  According to the electrophotographic toner manufacturing method described above, an electrophotographic toner excellent in toner blocking resistance, image storage stability, and low-temperature fixability can be provided.

  In addition, when the crystalline polyester resin has a cross-linked structure due to an unsaturated bond, it has a particularly wide fixing latitude with good offset resistance and a toner in a recording medium such as paper. Thus, an electrophotographic toner that can satisfy the prevention of excessive penetration of the toner can be obtained. Furthermore, it is possible to improve transfer efficiency by making the toner particle shape spherical.

[2] Electrophotographic developer:
The electrophotographic developer of the present invention includes an electrophotographic toner and a carrier, and the electrophotographic toner is the electrophotographic toner of the present invention.

  The carrier that can be used for the electrophotographic developer of the present invention that is the two-component developer is not particularly limited, and a known carrier can be used. 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 carrier core material 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, a magnetic material is used. Preferably there is. The volume average particle diameter of the core material of the carrier is preferably in the range of 10 to 500 μm, and more preferably in the range of 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 (mass ratio) of the electrophotographic toner of the present invention and the carrier in the two-component developer is preferably in the range of toner: carrier = 1: 100 to 30: 100, and 3: 100 to 20 : The range of about 100 is more preferable.

[3] Image forming method:
Next, the image forming method of the present invention using the electrophotographic toner of the present invention will be described. The image forming method includes a latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, a developing step of developing the electrostatic latent image with a developer to form a toner image, and a latent image holding member. An image forming method comprising: a transfer step of transferring a toner image formed on a surface to a recording medium to form a transfer image; and a fixing step of fixing the transfer image transferred to the recording medium, wherein the development The agent contains the electrophotographic toner of the present invention.

  As described above, the developer may be either a one-component system or a two-component system. In the case of a one-component system, the electrophotographic toner of the present invention is used as it is. In the case of a two-component system, the two-component developer of the present invention in which the electrophotographic toner of the present invention and a carrier are mixed is used. It is done.

  As each of the above steps, a known step in the image forming method can be used. As the latent image holding member, for example, an electrophotographic photosensitive member and a dielectric recording member can be used. In the case of an electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is uniformly charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic latent image (latent image forming step). Next, the toner particles are attached to the electrostatic latent image by bringing the toner particles into contact with or in proximity to a developing roll having a developer layer formed on the surface, thereby forming a toner image on the surface of the electrophotographic photosensitive member (developing step). The formed toner image is transferred onto the surface of a recording medium such as paper using a corotron charger or the like (transfer process). Further, the toner image transferred to the surface of the recording medium is thermally fixed by a fixing device, and a final toner image is formed. In the heat fixing by the fixing device, release oil is usually supplied to a fixing member in the fixing device in order to prevent an offset or the like.

  The image forming method of the present invention preferably further includes a cleaning process, and the cleaning process in the cleaning process is a cleaning process for removing toner remaining on the surface of the photoreceptor after the development process and the transfer process. It is preferable that any one of the following conditions (1) to (3) is satisfied.

(1) The thickness of the conductive substrate of the photoreceptor is 1.4 mm or more and 2.2 mm or less.
(2) The cleaning means in the cleaning process is held by a support member and has an elastic blade that is in contact with the surface of the photosensitive member with a contact pressure of 20 g / cm to 40 g / cm. .
(3) The contact angle of the elastic blade is 9 ° or more and 17 ° or less.

  The surface layer of the photoreceptor is preferably an organic photoreceptor containing fluorine resin particles.

  In such a cleaning process, when the thickness of the conductive substrate is 1.4 mm or more and 2.2 mm or less, and the linear pressure of the elastic blade is less than 20 g / cm or the contact angle is less than 9 °, the blade squeaks. Does not occur, but poor cleaning may occur frequently. On the other hand, when the linear pressure of the elastic blade is larger than 40 g / cm or the contact angle is larger than 17 °, there is no occurrence of poor cleaning, but blade squeal frequently occurs, and blade curl occurs depending on the case. The blade and the surface layer of the photoreceptor may be damaged.

  In addition, when the thickness of the conductive substrate is less than 1.4 mm, there is no influence on the cleaning property, but blade squealing is likely to occur, and there is a range in which good cleaning performance is acquired and blade squealing is compatible. The disadvantage of being narrowed arises. Further, when the thickness of the conductive substrate is 2.2 mm or more, it is difficult to tolerate the disadvantages such as the cost increase of the conductive substrate itself and the decrease in workability associated with the increase in weight.

  Further, the inclusion of fluorine resin particles in the surface layer of the photosensitive member improves the cleaning properties. When the fluorine resin particles are not contained, cleaning failure tends to occur.

  As the layer structure of the photoreceptor (undercoat layer, charge transport layer, charge generation layer, surface layer, etc.), conventionally known structures can be employed. In addition, the fluororesin includes tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodiethylene chloride resin and copolymers thereof. It is desirable to appropriately select one or two or more types from among them, but particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin. Specifically, product name: Fullon PTFE (Asahi Glass Co., Ltd.), product name: Fullon ETFE (Asahi Glass Co., Ltd.), product name; Kureha KF Polymer (Kureha Science Co., Ltd.), product name; Etc.

  In the cleaning means, in order to bring the elastic blade into contact with the surface of the rotating photoreceptor, generally, a flat elastic blade 1 having a constant thickness is held on a support member 2 as shown in FIG. The tip of the elastic blade 1 is preferably brought into contact with the surface of the rotating photoreceptor 3.

Then, the contact surface of the elastic blade 1 that contacts the photoreceptor 3 and the photoreceptor 3 at the contact point 4.
The contact angle θ of the elastic blade 1 formed on the rotational direction side of the photosensitive member 3 is set to 9 to 17 °, and the contact force (linear pressure) f of the elastic blade to the organic photosensitive member is set to 20 It is preferable to set to ˜40 g / cm.

  The cleaning device in the image forming apparatus according to the image forming method of the present invention is configured such that an elastic blade as a cleaning blade is provided in the opening of the box, and residual toner and the like removed from the surface of the photosensitive member are contained in the box. It is preferable that the structure is accommodated.

  In addition, the configurations of the image input device (latent image forming unit), the developing unit (developing unit), the transfer unit (transfer unit), the static eliminator, and the fixing unit are not particularly limited in the present invention. Any conventionally known configuration can be applied as it is.

  The image forming method of the present invention will be described using the electrophotographic apparatus of FIG. The surface of the electrophotographic photoreceptor 10 is uniformly charged by the charger 11 of the charging unit 12, and a latent image is formed by the image input unit (latent image forming unit) 13 (latent image forming step). The latent image formed on the surface of the electrophotographic photosensitive member 10 is developed with the electrophotographic toner of the present invention incorporated in the developing device (developing means) 14 to form a toner image (developing step). The toner image formed on the surface of the electrophotographic photosensitive member 10 is transferred to the surface of the transfer target member inserted between the electrophotographic photosensitive member 10 and a transfer device (transfer means) 15 facing the electrophotographic photosensitive member 10 (transfer process). Further, the image is fixed by heat and / or pressure of a fixing device (not shown). On the other hand, the residual toner on the surface of the electrophotographic photosensitive member 10 after the transfer is removed by a cleaning device (cleaning means) 16 having a cleaning blade 19 (cleaning step). Further, before proceeding to the next image forming cycle, the residual potential on the surface of the electrophotographic photosensitive member 10 is removed by the static eliminator 17.

  As a material of the cleaning blade, urethane rubber, silicon rubber, fluorine rubber, chloroprene rubber, butadiene rubber, or the like can be used. Among them, it is preferable to use a polyurethane elastic body because of its excellent wear resistance.

  As the polyurethane elastic body, a polyurethane generally synthesized through an addition reaction between an isocyanate and a polyol and various hydrogen-containing compounds is used. As a polyol component, a polyether-based polyol such as polypropylene glycol or polytetramethylene glycol, Polyester polyols such as adipate polyols, polycaprolactam polyols, polycarbonate polyols and the like, and polyisocyanate components such as tolylene diisocyanate, 4,4'diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, toluidine diisocyanate, etc. Polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclo It is manufactured by preparing a urethane prepolymer using an aliphatic polyisocyanate such as xylmethane diisocyanate, adding a curing agent to the urethane prepolymer, pouring it into a predetermined mold, crosslinking and curing, and then aging at room temperature. ing.

As the curing agent, a dihydric alcohol such as 1,4-butanediol and a trihydric or higher polyhydric alcohol such as trimethylolpropane or pentaerythritol are usually used in combination. As the physical properties of the cleaning blade, for example, hardness (JISA scale) 50 to 90, Young's modulus (kg / cm ² ) 40 to 90, 100% modulus (kg / cm ² ) 20 to 65, 300% modulus (kg / cm ²⁾ ) 70-150, tensile strength (kg / cm ² ) 240-500, elongation (%) 290-500, rebound resilience (%) 30-70, tear strength (kg / cm ² ) 25-75, permanent Those having an elongation (%) of 4.0 or less can be used.

  In the electrophotographic toner of the present invention, when the binder resin has a cross-linked structure, it is excellent in releasability due to its effect, and the amount of release oil used for the fixing member is reduced or its release. Fixing can be performed without using mold oil.

The release oil is preferably not used from the viewpoint of eliminating the adhesion of the oil to the transfer target and the image after fixing. However, when the supply amount of the release oil is 0 mg / cm ² , the fixing member and the paper are fixed during fixing. When the recording medium comes into contact with the recording medium, the amount of wear of the fixing member may increase, and the durability of the fixing member may decrease. If necessary, the amount of release oil used is 8.0. It is preferable that a small amount is supplied to the fixing member in a range of × 10 ⁻³ mg / cm ² or less.

When the supply amount of release oil exceeds 8.0 × 10 ⁻³ mg / cm ² , the image quality deteriorates due to the release oil adhering to the image surface after fixing, and in particular, transmitted light such as OHP is used. In such a case, such a phenomenon may appear remarkably. Further, the release oil adheres remarkably to the recording medium, and stickiness may occur. Furthermore, the larger the supply amount of the release oil, the larger the capacity of the tank for storing the release oil, which becomes a factor of increasing the size of the fixing device itself.

  The release oil is not particularly limited, and examples thereof include liquid release oil such as dimethyl silicone oil, fluorine oil, modified silicone oil such as fluorosilicone oil and amino-modified silicone oil. Among these, from the viewpoint of adsorbing on the surface of the fixing member and forming a uniform release oil layer, a modified oil such as amino-modified silicone oil is preferable because of its excellent wettability to the fixing member. From the viewpoint of forming a homogeneous release oil layer, fluorine oil and fluorosilicone oil are preferred.

  The reason why the fluorine oil or fluorosilicone oil is used as the release oil is that the electrophotographic toner of the present invention is not used. In the conventional image forming method, the supply amount of the release oil itself cannot be reduced. Although not practical in terms of cost, when the electrophotographic toner of the present invention is used, the supply amount of release oil can be drastically reduced, so there is no practical problem in terms of cost.

  There is no particular limitation on the method for supplying the release oil to the surface of the roller or belt that is a fixing member used for thermocompression bonding. For example, a pad method using a pad impregnated with a liquid release oil, a web method, a roller method. Non-contact shower method (spray method) and the like, and the web method and the roller method are particularly preferable. These methods are advantageous in that the release oil can be supplied uniformly and it is easy to control the supply amount. In order to supply the release oil uniformly to the entire fixing member by the shower method, it is necessary to use a separate blade or the like.

  The supply amount of the release oil can be measured as follows. That is, when a normal paper (typically, a copy paper manufactured by Fuji Xerox Co., Ltd., trade name J paper) used in a general copying machine is passed through a fixing member supplied with release oil on its surface. The release oil adheres to the surface of the plain paper. The attached release oil is extracted using a Soxhlet extractor. Here, hexane is used as the solvent. By quantifying the amount of release oil contained in hexane with an atomic absorption analyzer, the amount of release oil adhering to plain paper can be quantified. This amount is defined as the amount of release oil supplied to the fixing member.

  Examples of the recording material (recording material) to which the toner image is transferred include plain paper and OHP sheet used for electrophotographic copying machines, printers, and the like. In order to further improve the smoothness of the image surface after fixing, the surface of the recording medium is preferably as smooth as possible. For example, coated paper in which the surface of plain paper is coated with a resin or the like, art paper for printing Etc. can be used suitably.

  According to the image forming method using the electrophotographic toner of the present invention, since there is no aggregation of the toner, an image with excellent image quality can be formed, low temperature fixing is possible, and storage of the formed image is possible. Excellent in properties. Further, when the binder resin has a cross-linked structure, there is almost no adhesion of the release oil to the recording material, so a recording material to which adhesiveness is imparted on the back side such as a seal or tape is used. By forming an image, it is possible to manufacture a sticker, a sticker or the like on which a high-density and high-density image is formed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

<Example 1>
(Manufacture of toner)
-Synthesis of crystalline polyester resin (1)-
In a 5 L flask, 400 g (1.98 mol) of sebacic acid, 277.5 g (2.47 mol) of 1,6-hexanediol, 96.1 g (0.49 mol) of dimethyl terephthalate, and dibutyltin oxide 0.3 g was added, and the mixture was reacted at 180 ° C. for 5 hours with mechanical stirring under a nitrogen atmosphere, followed by a condensation reaction at 220 ° C. under reduced pressure.

  The polymer was sampled midway, the molecular weight was measured by gel permeation chromatography (GPC), and the reaction was stopped when the weight average molecular weight Mw was 21,000 and the number average molecular weight Mn was 9000.

  When melting | fusing point (Tm) of the obtained crystalline polyester resin (1) was measured using the differential scanning calorimeter (DSC) with the above-mentioned measuring method, the temperature of the peak top was 68.6 degreeC.

-Synthesis of crystalline polyester resin (2)-
In a 5 L flask, 500 g (2.47 mol) of sebacic acid, 365.2 g (3.09 mol) of 1,6-hexanediol and 151 g (0.618 mol) of dimethyl 2,6-naphthalenecarboxylate dibutyltin oxide 0.38 g was added and allowed to react at 180 ° C. for 5 hours under a nitrogen atmosphere with mechanical stirring, followed by a condensation reaction at 220 ° C. under reduced pressure.

  The polymer was sampled midway, the molecular weight was measured by gel permeation chromatography (GPC), and the reaction was stopped when the weight average molecular weight Mw was 23000 and the number average molecular weight Mn was 11100.

  When melting | fusing point (Tm) of the obtained crystalline polyester resin (2) was measured using the differential scanning calorimeter (DSC) with the above-mentioned measuring method, the peak top temperature was 67.5 degreeC.

-Synthesis of crystalline polyester resin (3)-
In a 5 L flask, 1436 g (7.1 mol) of sebacic acid, 934.8 g (7.91 mol) of 1,6-hexanediol, 213.3 g (0.79 mol) of dimethyl biphenylcarboxylate, dibutyltin oxide 0.98 g was added, and the mixture was allowed to react at 180 ° C. for 5 hours under a nitrogen atmosphere with mechanical stirring, followed by a condensation reaction at 220 ° C. under reduced pressure.

  The polymer was sampled on the way, the molecular weight was measured by gel permeation chromatography (GPC), and the reaction was stopped when the weight average molecular weight Mw was 26000 and the number average molecular weight Mn was 12000.

  When melting | fusing point (Tm) of the obtained crystalline polyester resin (3) was measured using the differential scanning calorimeter (DSC) with the above-mentioned measuring method, the peak top temperature was 70.5 degreeC.

-Preparation of crystalline polyester compound (1)-
2.4 g of dimethyl 4,4′-biphenyldicarboxylate was added to 80 g of the crystalline polyester resin (1), and the mixture was stirred and mixed at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (1)-
40 g of the obtained crystalline polyester resin (1) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous dodecylbenzenesulfonic acid solution, while adding an emulsifier (Ultra Turrax T-50, The product was stirred at 8000 rpm using IKA to produce a crystalline polyester resin latex (1) having a volume average particle size of 350 nm.

-Preparation of crystalline polyester resin compound (2)-
To 80 g of the crystalline polyester resin (1), 2.4 g of dimethyl 2,6-naphthalenedicarboxylate was added, and the mixture was stirred and mixed at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (2)-
40 g of the obtained crystalline polyester resin compound (2) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous dodecylbenzenesulfonic acid solution, while adding an emulsifier (Ultra Turrax T-50). , Manufactured by IKA) at 8000 rpm to prepare a crystalline polyester resin latex (2) having an average particle size of 300 nm.

-Preparation of crystalline polyester resin compound (3)-
To 80 g of the crystalline polyester resin (1), 4.8 g of dimethyl 2,6-naphthalenedicarboxylate was added, and the mixture was stirred and mixed at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (3)-
40 g of the obtained crystalline polyester resin compound (3) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous solution of dodecylbenzenesulfonic acid while adding an emulsifier (Ultra Turrax T-50). , Manufactured by IKA) at 8000 rpm to produce a crystalline polyester resin latex (3) having a volume average particle diameter of 400 nm.

-Preparation of crystalline polyester resin compound (4)-
2.4 g of dimethyl 2,6-naphthalenedicarboxylate was added to 80 g of the crystalline polyester resin (2), and the mixture was stirred at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (4)-
40 g of the obtained crystalline polyester resin compound (4) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous dodecylbenzenesulfonic acid solution, while adding an emulsifier (Ultra Turrax T-50). , Manufactured by IKA) at 8000 rpm to prepare a crystalline polyester resin latex (4) having a volume average particle diameter of 450 nm.

-Preparation of crystalline polyester resin compound (5)-
To 80 g of the crystalline polyester resin (2), 4.8 g of dimethyl 2,6-naphthalenedicarboxylate was added, and the mixture was stirred and mixed at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (5)-
40 g of the obtained crystalline polyester resin compound (5) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous solution of dodecylbenzenesulfonic acid, while adding an emulsifier (Ultra Turrax T-50). , Manufactured by IKA) at 8000 rpm to produce a crystalline polyester resin latex (5) having a volume average particle size of 280 nm.

-Preparation of crystalline polyester resin compound (6)-
2.4 g of dimethyl 2,6-naphthalenedicarboxylate was added to 80 g of the crystalline polyester resin (3), and the mixture was stirred and mixed at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (6)-
40 g of the obtained crystalline polyester resin compound (6) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous dodecylbenzenesulfonic acid solution, while adding an emulsifier (Ultra Turrax T-50). , Manufactured by IKA), and stirred at 8000 rpm to prepare a crystalline polyester resin latex (6) having a volume average particle size of 300 nm.

-Preparation of crystalline polyester resin compound (7)-
To 80 g of the crystalline polyester resin (3), 4.8 g of dimethyl 2,6-naphthalenedicarboxylate was added, and the mixture was stirred and mixed at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (7)-
40 g of the obtained crystalline polyester resin compound (5) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous solution of dodecylbenzenesulfonic acid, while adding an emulsifier (Ultra Turrax T-50). , Manufactured by IKA), and stirred at 8000 rpm to prepare a crystalline polyester resin latex (7) having a volume average particle diameter of 360 nm.

-Preparation of pigment dispersion B-1-
Those having the following composition were mixed and dissolved, and dispersed by a homogenizer (manufactured by IKA, Ultra Turrax T50) and ultrasonic irradiation to obtain a blue pigment dispersion B-1 having a volume average particle diameter of 150 nm.

Cyan pigment C.I. I. Pigment Blue 15: 3 (copper phthalocyanine, manufactured by Dainippon Ink & Chemicals) 50 g
・ Anionic surfactant Neogen SC 5g
・ Ion exchange water 200g

-Preparation of release agent dispersion C-1-
The following composition was mixed, heated to 97 ° C., and then dispersed with a homogenizer (manufactured by IKA, Ultra Turrax T50). Thereafter, the mixture was dispersed with a gorin homogenizer (manufactured by Reiwa Shoji Co., Ltd.) and treated 20 times at 105 ° C. and 550 kg / cm ² to obtain a release agent dispersion C-1 having a volume average particle size of 190 nm.

・ Wax (WEP-2, manufactured by NOF Corporation) 25g
・ Anionic surfactant Neogen SC 5g
・ Ion exchange water 200g

-Preparation of toner for electrophotography (1)-
After mixing and dispersing the following composition in a round stainless steel flask with a homogenizer (manufactured by IKA, Ultra Tarrax T50), the contents in the flask were heated to 48 ° C. with stirring in an oil bath for heating, Hold at 48 ° C. for 30 minutes.

・ Crystalline resin latex (1) 600g
・ Pigment dispersion B-1 25g
-100 g of release agent dispersion C-1
-10% by weight polyaluminum chloride aqueous solution (Asada Chemical Co., Ltd.) 1.5g

  Thereafter, when the obtained contents were observed with an optical microscope, it was confirmed that aggregated particles having a particle size of about 4.5 μm were formed. Further, the temperature of the heating oil bath was raised and held at 60 ° C. for 1 hour. When the obtained contents were observed with an optical microscope, it was confirmed that aggregated particles having a particle size of about 6.5 μm were formed. The pH was adjusted to 5 with an aqueous sodium hydroxide solution, and then the temperature was raised to 75 ° C. with a heating oil bath, cooled, filtered, sufficiently washed with ion-exchanged water, and dried to obtain an agglomerated toner. .

  When the particle diameter of the electrophotographic toner (1) was measured with a Coulter counter, the volume average particle diameter was 6.4 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.28.

Here, the volume GSD is obtained by calculating 84% volume average particle diameter D84 and 16% volume average particle diameter D16, respectively, in a volume average particle size distribution curve measured using a Coulter counter. D16) It can be obtained by substituting for ^1/2 . Moreover, the said volume average particle diameter shows 50% volume average particle diameter D50.

(Evaluation of toner)
-Toner charge amount-
1.5 g of electrophotographic toner (1) and 30 g of a carrier (produced by Fuji Xerox: DC400 carrier) under a low temperature and low humidity environment (temperature: 10 ° C., humidity: 15% RH) under a high temperature and high humidity environment (temperature: 28 ° C., humidity: 85% RH) and left for 1 day. Then, each was mixed and stirred for 60 minutes with a Turbula stirrer, and the charge amount was measured with a blow-off tribo measuring device (manufactured by Toshiba).

-Evaluation of low-temperature fixability-
Using the obtained electrophotographic toner (1), an A color full-color copier (Fuji Xerox Co., Ltd.) with a modified fixing device was used to form an image on the surface of the recording paper, and the electrophotographic toner (1) The low temperature fixability was evaluated. In the evaluation, the temperature was changed from 80 ° C. to 200 ° C. at intervals of 10 ° C., and a fixed image was produced at each fixing temperature. The degree of peeling was observed, and the lowest fixing temperature at which the image hardly peeled off was measured as MFT (° C.) to evaluate the low-temperature fixing property. The results are shown in Table 1. If the fixing temperature is 130 ° C. or lower, it can be said that the low-temperature fixing property is excellent.

The test conditions for the low-temperature fixability are shown below.
[Test conditions]
Toner image: Solid image (40 mm x 50 mm)
Toner amount: 0.9 mg / cm ²
・ Recording paper: Fuji Xerox Co., Ltd. color copy paper (J paper)
・ Conveying speed: 160mm / sec
・ Silicone oil application amount: 1.6 × 10 ⁻³ mg / cm ²

-Evaluation of toner durability (shape change)-
Two sheets of recording paper on which a fixed image is formed at the lowest fixing temperature (MFT (° C.)) are superimposed on the image surface, and a load of 100 g / cm ² is applied in an environment of temperature 60 ° C. and humidity 85%. , Left for 7 days. The superimposed images were peeled off, the images were fused between the recording papers, and the presence or absence of transfer in the non-image area was visually observed and evaluated according to the following evaluation criteria.

-: There is almost no toner crushed in the developing unit or toner aggregated to 30 microns or more.
○: Toner crushed in the developing device or toner aggregated to 30 microns or more is slight, and there is no problem in practical use.
• Δ: Some deformation was observed but no problem in practical use. ×: Large deformation was observed, and practical use is not possible.

<Example 2>
-Preparation of toner (2) for electrophotography-
An electrophotographic toner (2) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (2) was used. When the particle diameter of the electrophotographic toner particles (2) was measured with a Coulter counter, the volume average particle diameter was 6.6 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.25.

(Evaluation of toner)
Evaluation of the toner of Example 1 was performed in the same manner as in Example 1 except that the electrophotographic toner (2) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Example 3>
-Preparation of toner (3) for electrophotography-
An electrophotographic toner (3) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (3) was used. When the particle diameter of the electrophotographic toner particles (3) was measured with a Coulter counter, the volume average particle diameter was 6.2 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.30.

(Evaluation of toner)
In the evaluation of the toner of Example 1, the evaluation was performed in the same manner as in Example 1 except that the electrophotographic toner (3) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Example 4>
-Preparation of toner for electrophotography (4)-
An electrophotographic toner (4) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (4) was used. When the particle size of the electrophotographic toner particles (4) was measured with a Coulter counter, the volume average particle size was 6.6 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.25.

(Evaluation of toner)
In the evaluation of the toner of Example 1, the evaluation was performed in the same manner as in Example 1 except that the electrophotographic toner (4) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Example 5>
-Preparation of toner (5) for electrophotography-
An electrophotographic toner (5) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (5) was used. When the particle diameter of the electrophotographic toner particles (5) was measured with a Coulter counter, the volume average particle diameter was 6.9 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.22.

(Evaluation of toner)
In the evaluation of the toner of Example 1, the evaluation was performed in the same manner as in Example 1 except that the electrophotographic toner (5) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Example 6>
-Preparation of toner for electrophotography (6)-
An electrophotographic toner (6) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (6) was used. When the particle diameter of the electrophotographic toner particles (6) was measured with a Coulter counter, the volume average particle diameter was 6.7 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.25.

(Evaluation of toner)
In the evaluation of the toner of Example 1, the evaluation was performed in the same manner as in Example 1 except that the electrophotographic toner (6) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Example 7>
-Preparation of toner (7) for electrophotography-
An electrophotographic toner (7) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (7) was used. When the particle size of the electrophotographic toner particles (7) was measured with a Coulter counter, the volume average particle size was 6.4 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.28.

(Evaluation of toner)
In the evaluation of the toner of Example 1, the evaluation was performed in the same manner as in Example 1 except that the electrophotographic toner (7) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Example 8>
-Synthesis of crystalline polyester resin (4)-
In a 5 L flask, 1600 g (7.91 mol) of sebacic acid, 934.8 g (7.91 mol) of 1,6-hexanediol, and 0.98 g of dibutyltin oxide were placed under mechanical stirring in a nitrogen atmosphere. The reaction was carried out at 180 ° C. for 5 hours, followed by a condensation reaction at 220 ° C. under reduced pressure.

  The polymer was sampled on the way, the molecular weight was measured by gel permeation chromatography (GPC), and the reaction was stopped when the weight average molecular weight Mw was 26000 and the number average molecular weight Mn was 12000.

  When melting | fusing point (Tm) of the obtained crystalline polyester resin (1) was measured using the differential scanning calorimeter (DSC) by the above-mentioned measuring method, the temperature of the peak top was 70.5 degreeC. To 80 g of the crystalline polyester resin (4), 4.8 g of dimethyl 2,6-naphthalenedicarboxylate was added and stirred at 160 ° C. for 30 minutes to obtain a crystalline resin compound (8).

  40 g of the obtained crystalline polyester resin (8) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous dodecylbenzenesulfonic acid solution, while adding an emulsifier (Ultra Turrax T-50, Using IKA, the mixture was stirred at 8000 rpm to obtain particles (8) (crystalline polyester resin latex (8)) having a particle size of about 0.3 μm.

<Preparation of electrophotographic toner (8)>
An electrophotographic toner (8) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (8) was used. When the particle diameter of the electrophotographic toner particles (8) was measured with a Coulter counter, the volume average particle diameter was 6.8 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.29.

(Evaluation of toner)
In the evaluation of the toner of Example 1, the evaluation was performed in the same manner as in Example 1 except that the electrophotographic toner (8) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Example 9>
-Preparation of crystalline polyester resin compound (9)-
10 g of dimethyl 2,6-naphthalenedicarboxylate was added to 80 g of the crystalline polyester resin (2), and the mixture was stirred at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (9)-
40 g of the obtained crystalline polyester resin compound (9) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous dodecylbenzenesulfonic acid solution, while adding an emulsifier (Ultra Turrax T-50). , Manufactured by IKA), and stirred at 8000 rpm to prepare a crystalline polyester resin latex (9) having a volume average particle size of 300 nm.

<Preparation of electrophotographic toner (9)>
An electrophotographic toner (9) was prepared in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (9) was used. When the particle diameter of the electrophotographic toner particles (9) was measured with a Coulter counter, the volume average particle diameter was 6.5 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.28.

(Evaluation of toner)
In the evaluation of the toner of Example 1, the evaluation was performed in the same manner as in Example 1 except that the electrophotographic toner (9) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Example 10>
-Preparation of crystalline polyester resin compound (10)-
10 g of dimethyl 4,4′-biphenyldicarboxylate was added to 80 g of the crystalline polyester resin (2), and the mixture was stirred at 160 ° C. for 30 minutes.

-Preparation of crystalline polyester resin latex (10)-
40 g of the obtained crystalline polyester resin compound (10) was added to 360 g of ion-exchanged water, heated to 90 ° C., and added with 8 g of a 10% by mass aqueous dodecylbenzenesulfonic acid solution, while adding an emulsifier (Ultra Turrax T-50). , Manufactured by IKA) at 8000 rpm to produce a crystalline polyester resin latex (10) having an average particle size of 300 nm.

<Preparation of electrophotographic toner (10)>
An electrophotographic toner (10) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that the crystalline polyester resin latex (10) was used. When the particle diameter of the electrophotographic toner particles (10) was measured with a Coulter counter, the volume average particle diameter was 6.7 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.27.

(Evaluation of toner)
In the evaluation of the toner of Example 1, the evaluation was performed in the same manner as in Example 1 except that the electrophotographic toner (10) was used instead of the electrophotographic toner (1). The results are shown in Table 1.

<Comparative Example 1>
An electrophotographic toner (11) was produced in the same manner as the electrophotographic toner (1) of Example 1 except that dimethyl biphenyldicarboxylate (low molecular weight compound) was not added. When the particle size of the electrophotographic toner particles (11) was measured with a Coulter counter, the volume average particle size was 6.5 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.26.

<Comparative example 2>
An electrophotographic toner (12) is produced in the same manner as the electrophotographic toner (1) of Example 1 except that 2.4 g of 12 hydroxystearic acid is added instead of dimethyl biphenyldicarboxylate (low molecular weight compound). did. When the particle diameter of the electrophotographic toner particles (12) was measured with a Coulter counter, the volume average particle diameter was 6.4 μm. The volume GSD, which is an index of the volume particle size distribution, was 1.25.

  Comparative Example 1 and Comparative Example 2 were also evaluated in the same manner as in Example 1. The results are shown in Table 1.

  As in the results of Table 1, by using the crystalline polyester resin used in Examples 1 to 10 and further mixing a predetermined low molecular weight compound, it is possible to achieve low temperature fixability and charging stability in a high temperature and high humidity environment. In addition to excellent properties, a toner that is difficult to deform in the developing machine could be obtained. On the other hand, in the comparative example, since the predetermined low molecular weight compound was not used, the toner was severely deformed and could not satisfy the practical performance as a printer toner that outputs a high-quality print.

<Example 11>
An electrophotographic developer was prepared by mixing 1.5 parts by mass of the electrophotographic toner (1) of Example 1 and 30 parts of a carrier (Fuji Xerox Co., Ltd .: DC400 carrier).

The electrophotographic developer was used as a developer of “Docu Print C 3530” manufactured by Fuji Xerox, a full color printing test was performed, and cleaning property and blade squeal evaluation were performed as follows. The undercoat layer, the charge generation layer, and the charge transport layer for the photoconductor are those for Docu Print C 3530, the thickness of the conductive substrate is 1.4 mm, and the surface layer contains fluorine resin fine particles. It was. The photosensitive member cleaning blade had a blade linear pressure of 20 g / cm ² and a blade contact angle of 9 °. Only changed and used for evaluation.

<Evaluation of cleaning properties>
In a 10 ° C./15% RH environment, one sheet of a solid image was printed by A3 vertical feed, and one sheet of a blank sheet was collected and visually checked for cleaning failure.

<Blade noise evaluation>
In an environment of 28 ° C./85% RH, 500 prints with an image density of 1% were printed in the single-sheet feeding mode, and the measurer sensory evaluated the blade noise.

  As a result of the said evaluation, all were favorable. That is, no cleaning failure occurred and no blade squeal occurred.

It is explanatory drawing explaining the cleaning process which concerns on the image forming method of this invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus applicable to an image forming method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Elastic blade 2 ... Support body member 3 ... Photoconductor 4 ... Contact point 5 ... Tangent line 10 ... Photoconductor 11 ... Charger 12 ... High voltage power supply 13 ... Exposure apparatus 14 ... Development apparatus 15 ... Transfer roll 17 ... Static elimination apparatus 19 ... Cleaning blade 20 ... toner recovery auger 21 ... film seal 22 ... intermediate transfer member

Claims (3)

An electrophotographic toner comprising a binder resin and a colorant,
The binder resin includes a crystalline polyester resin and a low molecular compound having at least one of a naphthalene skeleton and a biphenyl skeleton,
The toner for electrophotography, wherein the crystalline polyester resin contains 0.5 to 30 constituent mol% of an aromatic dicarboxylic acid-derived constituent component. An electrophotographic developer comprising an electrophotographic toner and a carrier,
The electrophotographic developer according to claim 1, wherein the electrophotographic toner is the electrophotographic toner according to claim 1. A latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, a developing step of developing the electrostatic latent image with a developer to form a toner image, and a toner formed on the surface of the latent image holding member An image forming method comprising a transfer step of transferring an image to a recording material to form a transfer image, and a fixing step of fixing the transfer image transferred to the recording material,
An image forming method, wherein the developer contains the electrophotographic toner according to claim 1.

Images