JP2017090544A - Electrophotographic toner - Google Patents

Abstract

The present invention relates to an electrophotographic toner containing a synthetic ester wax as a release agent and excellent in low-temperature fixability and black solid followability.
An electrophotographic toner containing a binder resin and a release agent, wherein the binder resin contains an alcohol component containing an aliphatic diol having 2 to 4 carbon atoms and an aromatic dicarboxylic acid compound. An electrophotographic toner comprising 60% by mass or more of an amorphous polyester having a number average molecular weight of 4,000 or more, wherein the release agent contains a synthetic ester wax. .
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Description

  The present invention relates to an electrophotographic toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

  In recent years, there has been a strong demand for improvement in low-temperature fixability of toners from the viewpoint of energy saving, that is, reduction of energy consumption in the fixing process as well as promotion of downsizing, high speed and high image quality of electrophotographic apparatuses.

  In addition, as a raw material monomer for a toner binder resin, a plant-derived short chain fat such as 1,2-propanediol is used in place of an aromatic monomer such as an alkylene oxide adduct of bisphenol A which has been widely used conventionally. Group-based monomers have attracted attention (see Patent Documents 1 and 2).

  Known toner waxes include natural waxes typified by carnauba wax, petroleum waxes typified by paraffin wax, synthetic waxes typified by low molecular weight polyethylene or polypropylene, and synthetic ester waxes. In general, natural waxes are easily compatible with toner in the original, but since there are many volatile components derived from impurities, synthetic waxes with low volatile components have recently attracted attention. For example, in the examples of Patent Documents 2 to 4, synthetic waxes such as polypropylene wax and paraffin wax are used.

JP 2013-178504 A Japanese Patent No. 2014-201634 Japanese Patent No. 2015-000906 Japanese Patent No. 2015-087414

  However, an electrophotographic toner containing an amorphous polyester using a short-chain aliphatic diol and a synthetic ester wax is not sufficient not only in low-temperature fixability but also in black solid followability.

  Accordingly, the present invention relates to an electrophotographic toner containing a synthetic ester wax as a release agent and having excellent low-temperature fixability and black solid followability.

The present invention is an electrophotographic toner containing a binder resin and a release agent,
The binder resin is a polycondensate of an alcohol component containing an aliphatic diol having 2 to 4 carbon atoms and a carboxylic acid component containing an aromatic dicarboxylic acid compound, and has a number average molecular weight of 4,000 or more. Containing 60% by mass or more of amorphous polyester,
The present invention relates to an electrophotographic toner in which the release agent contains a synthetic ester wax.

  The toner for electrophotography of the present invention contains a synthetic ester wax as a releasing agent, and exhibits excellent effects in low-temperature fixability and black solid followability.

An amorphous polyester that is a polycondensation product of an alcohol component containing an aliphatic diol having 2 to 4 carbon atoms and a carboxylic acid component containing an aromatic dicarboxylic acid compound is obtained by using an aromatic diol. In comparison, there was a property that water was easily absorbed due to the high concentration of ester groups and the presence of low molecular weight components. In particular, when a synthetic ester wax having a relatively good dispersibility with respect to polyester is used as a release agent, this low molecular weight component has a high affinity with the synthetic ester wax and is easily compatible with the synthetic ester wax. There was a fear that crystallization would be inhibited. If the crystallization is inhibited, the sharp melt property of the toner is impaired and the low temperature fixability may be deteriorated. Furthermore, the influence of the synthetic ester wax in which the crystallization is hindered deteriorates the dispersibility of the polyester and the fluidity of the toner.
On the other hand, as a result of intensive studies by the present inventors, by combining a high molecular weight amorphous polyester with a reduced low molecular weight and a synthetic ester wax, without inhibiting the crystallization of the synthetic ester wax, It was found that both low-temperature fixability and black solid followability can be achieved.

  That is, the electrophotographic toner of the present invention contains a binder resin and a release agent, and the binder resin contains an alcohol component containing an aliphatic diol having 2 to 4 carbon atoms and an aromatic dicarboxylic acid compound. Is a polycondensate with a carboxylic acid component containing an amorphous polyester having a number average molecular weight of 4,000 or more, and the release agent contains a synthetic ester wax.

  As described above, the amorphous polyester contained in the electrophotographic toner of the present invention as a binder resin is a carboxylic acid containing an alcohol component containing an aliphatic diol having 2 to 4 carbon atoms and an aromatic dicarboxylic acid compound. It is a polycondensate with an acid component.

  In the alcohol component, the aliphatic diol having 2 to 4 carbon atoms includes ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2, Examples include 3-butanediol and 1,4-butanediol. In this invention, it is preferable to contain the aliphatic diol which has the hydroxyl group couple | bonded with the secondary carbon atom from a viewpoint of improving preservability. As such aliphatic diol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, or 2,3-butanediol is preferable, and among these, 1,2-propanediol is more preferable.

  The content of the aliphatic diol having a hydroxyl group bonded to a secondary carbon atom is preferably 50 mol% or more, more preferably 60 mol% from the viewpoint of improving the storage stability in the aliphatic diol having 2 to 4 carbon atoms. The mol% or more, more preferably 70 mol% or more.

  In addition to aliphatic diols having a hydroxyl group bonded to a secondary carbon atom, aliphatic diols having 2 to 4 carbon atoms have a hydroxyl group at the end of the carbon chain from the viewpoint of low-temperature fixability. It is desirable to contain an α, ω-aliphatic diol, preferably an α, ω-linear alkanediol.

  The content of α, ω-aliphatic diol, preferably α, ω-linear alkanediol is preferably 10 mol% or more from the viewpoint of low-temperature fixability in aliphatic diols having 2 to 4 carbon atoms. Preferably, it is at least 20 mol%, and from the viewpoint of storage stability, it is preferably at most 50 mol%, more preferably at most 40 mol%, still more preferably at most 30 mol%.

  In addition, among aliphatic diols having 2 to 4 carbon atoms, a molar ratio of an aliphatic diol having a hydroxyl group bonded to a secondary carbon atom and an α, ω-aliphatic diol (a hydroxyl group bonded to a secondary carbon atom). The aliphatic diol / α, ω-aliphatic diol) is preferably 0.1 or more, more preferably 0.5 or more, still more preferably 1 or more, more preferably 2 or more, and low temperature fixing from the viewpoint of storage stability. From the viewpoint of safety, it is preferably 10 or less, more preferably 8 or less, still more preferably 5 or less, and still more preferably 3 or less.

  The content of the aliphatic diol having 2 or more and 4 or less carbon atoms is preferably 60 mol% or more, more preferably 80 mol% or more, and still more preferably 90 mol in the alcohol component from the viewpoint of low-temperature fixability and storage stability. % Or more, more preferably 95 mol% or more, and still more preferably 100 mol%.

  Examples of the other alcohol components include aromatic diols such as alkylene oxide adducts of bisphenol A, aliphatic diols having 5 or more carbon atoms, and trivalent or higher alcohols such as glycerin.

  On the other hand, in the carboxylic acid component, examples of the aromatic dicarboxylic acid compound include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl (C1-3) esters. In the present specification, such acids, anhydrides of these acids, and alkyl esters of the acids are collectively referred to as carboxylic acid compounds.

  The content of the aromatic dicarboxylic acid compound is preferably 50 mol% or more, more preferably 70 mol% or more, further preferably 80 mol% or more, and further preferably from the viewpoint of improving heat-resistant storage stability. Is 90 mol% or more.

  Other carboxylic acid components include fatty acids such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecyl succinic acid, dodecenyl succinic acid, etc. Aromatic dicarboxylic acids such as cyclohexanedicarboxylic acid; Trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid; and anhydrides of these acids, alkyl (1 to 3 carbon atoms) esters; Rosin Rosin modified with fumaric acid, maleic acid, acrylic acid or the like.

  The alcohol component may contain a monovalent alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate.

  From the viewpoint of reducing the acid value of the polyester, the equivalent molar ratio (COOH group / OH group) of the carboxylic acid component and the alcohol component is preferably 0.70 to 1.15, more preferably 0.75 to 1.10.

  The polycondensation reaction between the alcohol component and the carboxylic acid component is not particularly limited. For example, in an inert gas atmosphere, as necessary, an esterification catalyst, an esterification cocatalyst, a polymerization inhibitor, etc. Can be carried out at a temperature of about 180 ° C to 250 ° C. Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamate. Examples of the catalyst include gallic acid. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Preferably it is 1.0 mass part or less. The amount of esterification promoter used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. More preferably, it is 0.1 parts by mass or less.

Here, the method for obtaining an amorphous polyester having a number average molecular weight of 4,000 or more is not particularly limited.
(1) Step 1A: a step of polycondensing an alcohol component and a carboxylic acid component until the reaction rate reaches 70% or more and 99% or less, and Step 2A: the polycondensate obtained in Step 1A further has a sulfo group. A method for producing an amorphous polyester by a method comprising a step of adding an organic compound and performing polycondensation; and
(2) Step 1B: Step of polycondensation using alcohol component and carboxylic acid component in a molar ratio of 1.6 to 2.6 (alcohol component / carboxylic acid component) until the reaction rate exceeds 90%, and Step 2B: Fat The method including the step of removing the group diol includes a method of producing an amorphous polyester. From the viewpoint of improving the production yield of the amorphous polyester, the method (1) is preferred.

  The polycondensation of the alcohol component and the carboxylic acid component in the steps 1A and 1B is preferably performed in the presence of an esterification catalyst.

  As the esterification catalyst, a tin catalyst or a titanium catalyst is preferable from the viewpoint of reactivity, and a tin catalyst is preferable from the viewpoint of promptly reaching the target reaction rate and suppressing coloring.

  Examples of the tin catalyst include dibutyltin oxide and tin (II) 2-ethylhexanoate. From the viewpoints of reactivity, molecular weight adjustment, and resin physical property adjustment, tin (II) having no Sn—C bond is used. ) Compounds are preferred.

  As the tin (II) compound having no Sn-C bond, a tin (II) compound having no Sn-C bond and having a Sn-O bond, Sn-X (X represents a halogen atom) ) A tin (II) compound having a bond is preferable, and a tin (II) compound having a Sn-O bond is more preferable.

Examples of tin (II) compounds having Sn-O bonds include tin (II) oxalate, tin (II) acetate, tin (II) octoate, tin (II) 2-ethylhexanoate, and tin (II) laurate. , Tin (II) carboxylate having a carboxylic acid group having 2 to 28 carbon atoms such as tin (II) stearate, tin (II) oleate; octyloxy tin (II), lauroxy tin (II), stearoxy tin (II) ), Alkoxytin (II) having an alkoxy group having 2 to 28 carbon atoms such as oleyloxytin (II); tin (II) oxide; tin (II) sulfate, Sn—X (X represents a halogen atom) Examples of the tin (II) compound having a bond include tin (II) halides such as tin (II) chloride and tin (II) bromide, and among these, from the standpoint of charge rising effect and catalytic ability , (R ¹ COO) ₂ Sn (wherein R ¹ represents an alkyl group or alkenyl group having 5 to 19 carbon atoms), (R ² O) ₂ Sn (where R ² Is C 6-20 alk Alkoxy tin (II) and tin oxide represented by SnO (II) is preferably represented by a group or an alkenyl group), (R ¹ COO) fatty tin represented by ₂ Sn (II) and tin oxide ( II) is more preferred, tin (II) octoate, tin (II) 2-ethylhexanoate, tin (II) stearate and tin (II) oxide are more preferred, tin (II) 2-ethylhexanoate and oxidation Even more preferred is tin (II).

  As the titanium catalyst, a titanium compound having a Ti-O bond is preferable, and a compound having an alkoxy group having 1 to 28 carbon atoms, an alkenyloxy group having 2 to 28 carbon atoms, or an acyloxy group having 1 to 28 carbon atoms in total. More preferred is titanium diisopropylate bistriethanolamate.

  The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, further preferably 0.2 parts by mass or more, with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. The amount is preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, and still more preferably 1.0 parts by mass or less.

In Steps 1A and 1B, a compound having a benzene ring in which hydrogen atoms bonded to three adjacent carbon atoms are substituted with a hydroxyl group may be used as an esterification co-catalyst together with the esterification catalyst. Examples thereof include gallic acid and the like.
The amount of the esterification cocatalyst used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Below, more preferably 0.1 parts by mass or less.

  In Steps 1A and 1B, a radical polymerization inhibitor may be used from the viewpoint of preventing side reactions other than polycondensation. As the radical polymerization inhibitor, 4-tert-butylcatechol is preferable.

  In Steps 1A and 1B, the polycondensation is preferably performed in an inert gas atmosphere, and the reaction temperature is preferably 160 ° C. or higher, more preferably 180 ° C. or higher, from the viewpoint of reactivity and thermal decomposability of the monomer. And preferably 250 ° C. or lower, more preferably 240 ° C. or lower.

  In Step 1A, polycondensation is performed to reach a predetermined reaction rate. The reaction rate is preferably 70% or more, more preferably 80% or more from the viewpoint of improving the low-temperature fixability and storability of the obtained toner, and the polymerization in Step 2A is promoted, and the black solid followability From the viewpoint of improving the ratio, it is preferably 99% or less, more preferably 90% or less, and still more preferably 85% or less. The reaction rate in the present invention refers to a value of product reaction water amount (mol) / theoretical product water amount (mol) × 100.

  In step 2A, an organic compound having a sulfo group is added to the polycondensate obtained in step 1A (reaction system in step 1A) to perform polycondensation.

  The organic compound having a sulfo group in the present invention is preferably an aromatic compound having a sulfo group or an aliphatic compound having a sulfo group. However, from the viewpoint of dispersibility in a resin, compatibility with a polyester, and charging characteristics, An aromatic compound having a group is more preferable.

  Examples of aromatic compounds having a sulfo group include p-toluenesulfonic acid, isotoluenesulfonic acid, metatoluenesulfonic acid, benzenesulfonic acid, p-xylene-2-sulfonic acid, naphthalene-1-sulfonic acid, and naphthalene-2-sulfone. Acid, aminobenzenesulfonic acid, 2-aminotoluene-5-sulfonic acid, 8-amino-2-naphthalenesulfonic acid, 4-biphenylsulfonic acid, benzene-1,3-sulfonic acid, para-toluenesulfonic acid-2 butynyl, P-Toluenesulfonic acid-3butynyl, p-toluenesulfonic acid-2chloroethyl, p-toluenesulfonic acid cyclohexyl, 2,5-dimethylbenzenesulfonic acid, dodecylbenzenesulfonic acid, ethyl benzenesulfonate, ethyl p-toluenesulfonate, bis- ethylene glycol p-toluenesulfonate, isobutyl p-toluenesulfonate, Methyl sulfonate, 1,3,6-naphthalene trisulfonic acid, 1-naphthol-2-sulfonic acid, salts of these compounds (sodium salt, potassium salt, etc.), hydrates, methyl ester compounds, etc. . Among these, alkylbenzenesulfonic acid in which an alkyl group is substituted on the benzene ring is preferable from the viewpoint of improving the reactivity of the polyester monomer and improving the low-temperature fixability, storage stability and durability of the resulting toner. The number of carbon atoms of the alkyl group substituted on the benzene ring is preferably 1 or more from the viewpoint of improving the reactivity of the polyester monomer and improving the low-temperature fixability and black solid followability of the obtained toner, and preferably It is 22 or less, more preferably 14 or less, and further preferably 6 or less.

  Examples of the aliphatic compound having a sulfo group include ethanesulfonic acid, 1,2-ethanedisulfonic acid, hydroxyamine-O-sulfonic acid, methanesulfonic acid, ethyl methanesulfonate, trifluoromethanesulfonic acid, 1-butanesulfonic acid, 1-decanesulfonic acid, 1-heptanesulfonic acid, 1-hexanesulfonic acid, 3-hydroxypropanesulfonic acid, 1-nonanesulfonic acid, 1-octanesulfonic acid, 1-pentanesulfonic acid, 1,3-propanedisulfonic acid 1-dodecanesulfonic acid, 1-hexadecanesulfonic acid, 1-propanesulfonic acid, vinylsulfonic acid and its salts, hydrates, and the like.

  The organic compound having a sulfo group is preferably used in an amount of 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component used in Step 1A from the viewpoint of improving the low-temperature fixability and black solid followability of the obtained toner. 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and from the viewpoint of improving the storage stability of the obtained toner, preferably 100 parts by mass with respect to the total amount of the alcohol component and carboxylic acid component used in Step 1A. 0.5 parts by mass or less, more preferably 0.2 parts by mass or less.

  When using a tin catalyst or a titanium catalyst in step 1A, the mass ratio of the tin catalyst or titanium catalyst and the organic compound having a sulfo group used in step 2A (tin catalyst or titanium catalyst / an organic compound having a sulfo group) is: From the viewpoint of improving the low-temperature fixability and black solid followability of the obtained toner, it is preferably 1/2 or more, more preferably 1/1 or more, and preferably 50/1 or less, more preferably 20/1. It is as follows.

  Also in step 2A, the polycondensation is preferably performed in an inert gas atmosphere. From the viewpoint of reactivity and thermal decomposition of the monomer, the reaction temperature is preferably 160 ° C. or higher from the viewpoint of reactivity. The temperature is preferably 200 ° C. or higher, and preferably 240 ° C. or lower, more preferably 230 ° C. or lower, from the viewpoint of the thermal decomposability of the polyester produced in Step 1A.

  In the present invention, the amorphous polyester means a resin containing a polyester unit formed by polycondensation of an alcohol component and a carboxylic acid component, and has two or more resin components including polyester, polyester polyamide, and polyester component. A composite resin, for example, a hybrid resin in which a polyester component and an addition polymerization resin component are partially chemically bonded via both reactive monomers is also included. The content of the polyester unit is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 95% in the amorphous polyester from the viewpoint of low-temperature fixability and durability. It is at least mass%, more preferably 100 mass%.

  Further, the amorphous polyester may be modified to such an extent that the characteristics are not substantially impaired. For example, the modified polyester may be grafted or blocked with phenol, urethane, epoxy or the like by the method described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc. Polyester.

  The number average molecular weight of the amorphous polyester is 4,000 or more, preferably 4,500 or more, and preferably 10,000 or less, more preferably 7,000 or less, from the viewpoint of low-temperature fixability and black solid followability. The number average molecular weight in the case of containing two or more kinds of amorphous polyesters is a value obtained by weighted average.

  The low molecular weight fraction in the tetrahydrofuran (THF) soluble part of the amorphous polyester is preferably 6.0% by mass or less, more preferably 5.0% by mass or less from the viewpoint of improving the black solid followability. The low molecular weight fraction is preferably 1.0% by mass or more, more preferably 2.0% by mass or more from the viewpoint of improving the low-temperature fixability.

  The softening point of the amorphous polyester is preferably 90 ° C. or more, more preferably 100 ° C. or more from the viewpoint of storage stability, and preferably 160 ° C. or less, more preferably 150 ° C. from the viewpoint of low-temperature fixability. Hereinafter, it is more preferably 145 ° C. or lower.

  The glass transition temperature of the amorphous polyester is preferably 45 ° C. or higher, more preferably 50 ° C. or higher from the viewpoint of storage stability, and preferably 85 ° C. or lower, more preferably 80 ° C. from the viewpoint of low-temperature fixability. ° C or lower, more preferably 75 ° C or lower.

  The acid value of the amorphous polyester is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, further preferably 5 mgKOH / g or more, from the viewpoint of improving productivity, and from the viewpoint of heat-resistant storage stability. , Preferably 30 mgKOH / g or less, more preferably 25 mgKOH / g or less, and still more preferably 20 mgKOH / g or less.

  The crystallinity of the resin is represented by the ratio between the softening point and the maximum endothermic peak temperature measured by a differential scanning calorimeter, that is, the crystallinity index defined by the value of [softening point / maximum endothermic peak temperature]. The crystalline resin is a resin having a crystallinity index of 0.6 or more and 1.4 or less, preferably 0.7 or more and 1.2 or less, more preferably 0.9 or more and 1.2 or less, and further preferably 0.9 or more and 1.1 or less. Resins having an index greater than 1.4, less than 0.6, preferably greater than 1.5, 0.5 or less, more preferably 1.6 or more, or 0.5 or less. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, production conditions (for example, reaction temperature, reaction time, cooling rate) and the like. The highest endothermic peak temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. In the crystalline resin, the highest endothermic peak temperature is the melting point.

  In the present invention, the amorphous polyester preferably contains two kinds of polyesters having different softening points from the viewpoint of high-temperature offset resistance and low-temperature fixability.

  The softening point of polyester H having the higher softening point is preferably 110 ° C. or higher, more preferably 130 ° C. or higher from the viewpoint of high-temperature offset resistance, and preferably 170 ° C. or lower from the viewpoint of low-temperature fixability. More preferably, it is 160 ° C. or lower.

  The softening point of the polyester L having the lower softening point is preferably 80 ° C. or higher, more preferably 95 ° C. or higher from the viewpoint of durability, and preferably 125 ° C. or lower, from the viewpoint of low-temperature fixability. Preferably it is 115 degrees C or less.

  The difference in softening point between polyester H and polyester L is preferably 10 ° C. or higher, more preferably 20 ° C. or higher, from the viewpoint of high temperature offset resistance and low temperature fixability, and preferably 60 ° C. from the viewpoint of chargeability. C. or lower, more preferably 50 C or lower.

  The mass ratio of polyester H to polyester L (polyester H / polyester L) is preferably 20/80 or more, more preferably 40/60 or more, from the viewpoint of durability and productivity, and from the viewpoint of low-temperature fixability. Therefore, it is preferably 80/20 or less, more preferably 60/40 or less.

  In the electrophotographic toner of the present invention, a known binder resin other than the amorphous polyester, for example, other amorphous polyester, vinyl type such as styrene-acrylic resin, and the like, as long as the effects of the present invention are not impaired. Other resins such as resin, epoxy resin, polycarbonate, and polyurethane may be used in combination, but the content of the amorphous polyester is 60% by mass or more in the binder resin from the viewpoint of low-temperature fixability. Preferably it is 80 mass% or more, More preferably, it is 90 mass% or more, More preferably, it is 95 mass% or more, More preferably, it is 100 mass%.

  In the present invention, the release agent contains a synthetic ester wax.

  The content of the synthetic ester wax is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, further preferably 90% by mass or more, and further preferably 95% by mass in the release agent. More preferably, it is 100% by mass, that is, the release agent may consist only of synthetic ester wax.

  In the present invention, the “synthetic ester wax” is an ester compound obtained by reacting a carboxylic acid with an alcohol. Among them, from the viewpoint of improving the low-temperature fixability, storage stability, and black solid followability of the toner, an ester obtained by reacting a monovalent aliphatic alcohol having 14 to 24 carbon atoms with a fatty acid having 14 to 24 carbon atoms and / or Alternatively, an ester obtained by reacting pentaerythritol with a fatty acid having 14 to 24 carbon atoms is preferable, and an ester obtained by reacting a monovalent aliphatic alcohol having 18 to 24 carbon atoms with a fatty acid having 18 to 24 carbon atoms and / or An ester obtained by reacting pentaerythritol with a fatty acid having 18 to 24 carbon atoms is more preferable. Further, the most numerous component of the wax may have at least one ester group in the structure, and the proportion of the most numerous component in the composition distribution of the wax may be 80% by mass or more.

  As synthetic ester wax, WEP-2, WEP-3, WEP-3R, WEP-4, WEP-5, WEP-6, WEP-7, WEP-8, WE-10 (above, NOF Corporation, Any of them may be trade names).

  In contrast, natural ester waxes include carnauba wax, candelilla wax, rice wax, and derivatives thereof.

  In the present invention, from the viewpoint of preventing the volatilization of the toner component, it is preferable that the natural wax, particularly carnauba wax, contained in the release agent is small, and the content thereof is preferably 20% by mass or less in the release agent. Preferably it is 10 mass% or less, More preferably, it is 5 mass% or less, More preferably, it is 3 mass% or less, More preferably, it is 1 mass% or less, More preferably, it is 0 mass%, ie, it is preferable not to contain.

  In the present invention, a synthetic wax other than the synthetic ester wax may be used as a release agent within a range that does not impair the effects of the present invention. As release agents other than such synthetic ester wax, aliphatic hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene polyethylene copolymer, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, sazol wax, and the like Oxides, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like.

  The melting point of the release agent is preferably 60 ° C. or higher, and preferably 160 ° C. or lower, more preferably 150 ° C. or lower, from the viewpoint of low-temperature fixability and offset resistance of the toner.

  The content of the release agent is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, more preferably 3 parts by mass or less, from the viewpoint of black solid followability with respect to 100 parts by mass of the binder resin. Preferably it is 2.5 mass parts or less. Further, from the viewpoint of low-temperature fixability and offset resistance of the toner, it is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further preferably 1 part by mass or more.

  The toner further contains additives such as colorants, charge control agents, magnetic powders, fluidity improvers, conductivity modifiers, reinforcing fillers such as fibrous substances, antioxidants, and cleanability improvers. It is preferable that a colorant and a charge control agent are contained.

  As the colorant, dyes, pigments and the like used as toner colorants can be used. For example, carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow . In the present invention, the toner particles may be either black toner or color toner.

  The content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass with respect to 100 parts by mass of the binder resin from the viewpoint of improving the image density of the toner. Part or less, more preferably 10 parts by weight or less.

  The charge control agent is not particularly limited, and may contain either a positively chargeable charge control agent or a negatively chargeable charge control agent.

  Examples of positively chargeable charge control agents include nigrosine dyes such as “Nigrosine Base EX”, “Oil Black BS”, “Oil Black SO”, “Bontron N-01”, “Bontron N-04”, “Bontron N-07 ”,“ Bontron N-09 ”,“ Bontron N-11 ”(manufactured by Orient Chemical Co., Ltd.), etc .; triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, for example “Bontron P-51” (manufactured by Orient Chemical Co., Ltd.), cetyltrimethylammonium bromide, “COPY CHARGE PX VP435” (manufactured by Clariant), etc .; polyamine resins such as “AFP-B” (Orient Chemical Co., Ltd.) Imidazole derivatives such as “PLZ-2001”, “PLZ-8001” (manufactured by Shikoku Kasei Kogyo Co., Ltd.), etc .; styrene-acrylic resins such as “FCA-701PT” (Fujikura Kasei Co., Ltd.) ), And the like.

  In addition, as the negatively chargeable charge control agent, metal-containing azo dyes such as “Varifast Black 3804”, “Bontron S-31”, “Bontron S-32”, “Bontron S-34”, “Bontron S-36” (Above, Orient Chemical Industry Co., Ltd.), “Eisenspiron Black TRH”, “T-77” (Hodogaya Chemical Co., Ltd.), etc .; metal compounds of benzylic acid compounds, such as “LR- 147 ”,“ LR-297 ”(manufactured by Nippon Carlit Co., Ltd.), etc .; metal compounds of salicylic acid compounds, such as“ Bontron E-81 ”,“ Bontron E-84 ”,“ Bontron E-88 ”,“ "Bontron E-304" (manufactured by Orient Chemical Co., Ltd.), "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.), etc .; copper phthalocyanine dyes; quaternary ammonium salts such as "COPY CHARGE NX VP434" (Manufactured by Clariant), nitroimidazole derivatives, etc .; organic gold Genus compounds and the like.

  The content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass with respect to 100 parts by mass of the binder resin from the viewpoint of charge stability of the toner. Parts or less, more preferably 5 parts by mass or less, further preferably 3 parts by mass or less, and further preferably 2 parts by mass or less.

  The toner for electrophotography may be a toner obtained by any conventionally known method such as a melt-kneading method, an emulsion phase inversion method, or a polymerization method, but from the viewpoint of productivity and dispersibility of the colorant, A pulverized toner obtained by a melt kneading method is preferred. In the case of pulverized toner by the melt kneading method, for example, a binder resin and a release agent, and if necessary, raw materials such as a colorant and a charge control agent are uniformly mixed with a mixer such as a Henschel mixer, and then a sealed kneader. It can be produced by melt-kneading with a single-screw or twin-screw extruder, an open roll kneader, etc., cooling, pulverizing and classifying. Therefore, as a more preferable production method of the toner of the present invention, an amorphous polyester is produced by the method including the steps 1A and 1B, the obtained amorphous polyester, a binder resin and a release agent, A method including a step of melt-kneading, pulverizing, and classifying raw materials such as a colorant and a charge control agent, if necessary. On the other hand, from the viewpoint of reducing the particle size of the toner, a toner by a polymerization method is preferable. An external additive such as hydrophobic silica may be added to the surface of the toner.

  In the toner of the present invention, it is preferable to use an external additive in order to improve transferability. Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide and zinc oxide, and organic fine particles such as resin particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles. The above may be used in combination. Among these, silica is preferable, and hydrophobic silica that has been subjected to a hydrophobic treatment is more preferable from the viewpoint of toner transferability.

  Examples of hydrophobizing agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), and methyltriethoxysilane. It is done.

  The average particle diameter of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, from the viewpoint of toner chargeability, fluidity, and transferability. Preferably it is 90 nm or less.

  The content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass with respect to 100 parts by mass of the toner before being processed with the external additive, from the viewpoint of chargeability, fluidity and transferability of the toner. Part or more, more preferably 0.3 part by weight or more, and preferably 5 parts by weight or less, more preferably 3 parts by weight or less.

The volume median particle size (D ₅₀ ) of the toner of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size. When the toner is treated with an external additive, the volume median particle size of the toner particles before being treated with the external additive is defined as the volume median particle size of the toner.

  The toner of the present invention can be used in an image forming apparatus of a one-component development system or a two-component development system as a one-component development toner as it is or as a two-component development toner mixed with a carrier.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The physical properties of the resin and the like were measured by the following method.

[Softening point of resin]
Using a flow tester “CFT-500D” (manufactured by Shimadzu Corporation), a 1 g sample was heated at a heating rate of 6 ° C./min, and a 1.96 MPa load was applied by a plunger, and the diameter was 1 mm and the length was 1 mm. Extrude from the nozzle. The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[Maximum peak temperature of resin endotherm]
Using a differential scanning calorimeter “Q-20” (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample is weighed into an aluminum pan, and the temperature is reduced from room temperature to 10 ° C / min. Cool to 0 ° C and maintain at 0 ° C for 1 minute. Thereafter, the measurement is performed at a heating rate of 10 ° C./min. Among the observed endothermic peaks, the temperature of the peak on the highest temperature side is defined as the highest endothermic peak temperature.

[Glass transition temperature of resin]
Using a differential scanning calorimeter “Q-20” (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample was weighed into an aluminum pan, heated to 200 ° C., and from that temperature Cool to 0 ° C at a temperature drop rate of 10 ° C / min. Next, the sample is heated at a heating rate of 10 ° C./min, and the endothermic peak is measured. The glass transition temperature is defined as the temperature at the intersection of the base line extension below the maximum peak temperature of endotherm and the tangent line indicating the maximum slope from the peak rising portion to the peak apex.

[Acid value of the resin]
Measured according to the method of JIS K0070. However, only the measurement solvent is changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Number average molecular weight of resin]
The number average molecular weight is determined by gel permeation chromatography (GPC) by the following method.
(1) Preparation of sample solution Dissolve the sample in tetrahydrofuran at 40 ° C so that the concentration is 0.5 g / 100 mL. Next, this solution is filtered using a PTFE type membrane filter “DISMIC-25JP” (manufactured by Toyo Roshi Kaisha, Ltd.) having a pore size of 0.20 μm to remove insoluble components to obtain a sample solution.
(2) Molecular weight measurement Using the following measuring device and analytical column, tetrahydrofuran is flowed as an eluent at a flow rate of 1 mL per minute, and the column is stabilized in a constant temperature bath at 40 ° C. Inject 100 μL of the sample solution into the sample and perform measurement. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. The calibration curve at this time includes several types of monodisperse polystyrene (A-500 (5.0 × 10 ² ), A-1000 (1.01 × 10 ³ ), A-2500 (2.63 × 10 ³ ) manufactured by Tosoh Corporation, A-5000 (5.97 × 10 ³ ), F-1 (1.02 × 10 ⁴ ), F-2 (1.81 × 10 ⁴ ), F-4 (3.97 × 10 ⁴ ), F-10 (9.64 × 10 ⁴ ), F-20 (1.90 × 10 ⁵ ), F-40 (4.27 × 10 ⁵ ), F-80 (7.06 × 10 ⁵ ), F-128 (1.09 × 10 ⁶ )) prepared as standard samples are used. The molecular weight is shown in parentheses.
Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation)
Analytical column: TSKgel GMH _XL + TSKgel G3000H _XL (manufactured by Tosoh Corporation)

[Low molecular weight fraction in tetrahydrofuran (THF) solubles]
In the molecular weight distribution obtained by molecular weight measurement, the proportion of components having a molecular weight of 500 or less is defined as the low molecular weight fraction.

[Melting point of release agent]
Using a differential scanning calorimeter “DSC Q20” (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample is weighed into an aluminum pan and heated to 200 ° C. at a heating rate of 10 ° C./min. The temperature is raised and the temperature is cooled to -10 ° C at a rate of 5 ° C / min. Next, the sample is heated to 180 ° C. at a heating rate of 10 ° C./min and measured. The maximum peak temperature of the endotherm observed from the melting endotherm curve thus obtained is taken as the melting point of the release agent.

[Average particle diameter of external additive]
The average particle diameter refers to the number average particle diameter. The particle diameter (average value of major axis and minor axis) of 500 particles is measured from a scanning electron microscope (SEM) photograph, and the number average value thereof is used.

[Volume-median particle size of toner]
Measuring machine: Coulter Multisizer II (manufactured by Beckman Coulter, Inc.)
Aperture diameter: 100μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter, Inc.)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB (Griffin): 13.6) dissolved in the electrolyte to adjust to 5% by mass Dispersion condition: 10 mL of measurement sample in 5 mL of the dispersion Is added for 1 minute with an ultrasonic disperser (machine name: US-1 manufactured by SND Co., Ltd., output: 80 W), and then 25 mL of the electrolyte is added. For 1 minute to prepare a sample dispersion.
Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte so that the particle size of 30,000 particles could be measured in 20 seconds, and 30,000 particles were measured. Determine the median particle size (D ₅₀ ).

Resin Production Example 1 [Resin A1 to Resin A4]
The raw material monomer and esterification catalyst shown in Table 1 were put into a 10-liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a flow-down condenser and a nitrogen inlet tube, and in a mantle heater in a nitrogen atmosphere. After raising the temperature to 180 ° C, the temperature was raised to 210 ° C over 5 hours. Thereafter, it was confirmed that the reaction rate reached 70% or more at 210 ° C., and an organic compound having a sulfo group was added. Then, it heated up to 220 degreeC and it reacted until it reached the softening point shown in Table 1 at 8.0 kPa, and amorphous polyester was obtained. The reaction rate means a value of the amount of produced reaction water / theoretical product water amount × 100. Table 1 shows the reaction rate at the time of adding the esterification catalyst 2 in the production of each resin.

Resin Production Example 2 [Resin A5]
The raw material monomer and esterification catalyst shown in Table 1 were put into a 10-liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a fractionation tower, a dehydration tube, a cooling tube, and a nitrogen introduction tube, and a nitrogen atmosphere The temperature was raised to 185 ° C. in the mantle heater and reacted for 5 hours, and then the temperature was raised stepwise to 220 ° C. at a rate of 5 ° C./h. Thereafter, it was confirmed that the reaction rate reached 95% or higher at 220 ° C., and 1,2-propanediol was removed at 13.3 kPa, and at the same time, the reaction was performed until the desired softening point was reached. Obtained.

Resin Production Example 3 [Resin A6]
Raw material monomers and esterification catalyst other than trimellitic anhydride shown in Table 1 were placed in a 10 liter four-necked flask equipped with a nitrogen introduction tube, dehydration tube, stirrer, and thermocouple, and the temperature was 200 ° C under a nitrogen atmosphere. The temperature was raised to 6 hours and allowed to react for 6 hours. After heating to 210 ° C., trimellitic anhydride was added, reacted at normal pressure (101.3 kPa) for 1 hour, and further reacted at 40 kPa until the desired softening point was reached. Obtained. Table 1 shows the physical properties of the obtained resin.

Resin Production Example 4 [Resin A7]
The raw material monomer and esterification catalyst shown in Table 1 were put into a 10-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 200 ° C. in a nitrogen atmosphere. Reacted for hours. The temperature was further raised to 210 ° C., followed by reaction at normal pressure (101.3 kPa) for 1 hour, and further at 40 kPa until a desired softening point was reached to obtain an amorphous polyester. Table 1 shows the physical properties of the obtained resin.

[Example of toner production]
Examples 1-8 and Comparative Examples 1-6
100 parts by weight of binder resin and a predetermined amount of release agent shown in Table 2, 1.0 part by weight of charge control agent “Bontron E-304” (manufactured by Orient Chemical Co., Ltd.), and colorant “REGAL 330R” (Cabot) (Specialty Chemicals, Inc.) 5.0 parts by mass were mixed for 1 minute using a Henschel mixer and then melt-kneaded under the conditions shown below.

A co-rotating twin screw extruder “PCM-30” (manufactured by Ikegai Co., Ltd., shaft diameter 2.9 cm, shaft cross section 7.06 cm ² ) was used. Operating conditions are: barrel set temperature 100 ° C, shaft rotation speed 200r / min (shaft rotation peripheral speed 0.30m / sec), mixture supply speed 10kg / h (mixture supply rate per unit cross section of shaft 1.42kg / h)・ Cm ² ).

  The obtained resin kneaded product is cooled, coarsely pulverized by a pulverizer “ROTOPLEX” (manufactured by Hosokawa Micron Co., Ltd.), and a coarsely pulverized product having a volume-median particle diameter of 2 mm or less using a sieve having an opening of 2 mm. Obtained. The obtained coarsely pulverized product was finely pulverized by using a DS2 airflow classifier (impact plate type, manufactured by Nippon Pneumatic Co., Ltd.) so that the volume median particle size was adjusted to 8.0 μm. The resulting finely pulverized product is classified by adjusting the static pressure (internal pressure) so that the volume median particle size becomes 8.5 μm using a DSX2 type airflow classifier (manufactured by Nippon Pneumatic Co., Ltd.). Toner particles were obtained.

  100 parts by mass of the toner particles obtained, hydrophobic silica “R972” (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, average particle size: 16 nm) as an external additive, 0.5 parts by mass, and hydrophobic silica “ RY50 "(manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: silicone oil, average particle size: 40 nm) 1.0 part by mass using a Henschel mixer (manufactured by Nihon Coke Industries Co., Ltd.) 2100 r / min (circumferential speed 29 m / sec) for 3 minutes to obtain a toner.

Test Example 1 [low temperature fixability]
The printer “OKI MICROLINE 5400” (made by Oki Data Co., Ltd.), modified to take unfixed images, was filled with toner, and a 2cm square solid image unfixed image was printed. Using an external fixing device modified from "OKI MICROLINE 3010" (manufactured by Oki Data Co., Ltd.), the fixing roll temperature was increased by 5 ° C from 100 ° C to 230 ° C at a fixing roll rotation speed of 120mm / sec. The unfixed image was fixed at each temperature to obtain a fixed image. The image obtained at each fixing temperature is rubbed 5 times with a sand eraser (made by Lion Corporation, ER-502R) with a load of 500 g. (Gretag Macbeth Co., Ltd.) was used, and the temperature at which the image density ratio before and after rubbing ([image density after rubbing / image density before rubbing] × 100) first exceeded 85% was defined as the minimum fixing temperature. It was used as an index of fixability. The lower the minimum fixing temperature, the better the low-temperature fixing property. The results are shown in Table 2.

Test Example 2 [Black solid followability]
A non-magnetic one-component developer "OKI MICROLINE 5400" (made by Oki Data Co., Ltd.) is loaded with 50g of toner, and is run at 30 ° C and 85% humidity at 88r / min (equivalent to 45ppm) for 30 minutes. After the toner was collected, the toner was collected and filled in a printer “OKI MICROLINE 5400” (Oki Data Co., Ltd.), and an A4 size black solid image was printed. Note that J paper (Fuji Xerox Co., Ltd.) was used as the print medium. Measure the image density (ID ₁ ) of the central part 5 cm from the top of the black solid image and the image density (ID ₂ ) of the central part 5 cm from the bottom using “Gretag SPM50” (manufactured by Gretag Macbeth). The difference in image density between ID ₁ and ID ₂ ) was confirmed. When the difference in image density exceeded 0.4, the idling time was taken as the evaluation result of black solid followability, and when not exceeding 0.4, the idling time was extended by 30 minutes and evaluated in the same manner. The results are shown in Table 2.

  From the above results, in comparison with Comparative Examples 1 to 6, the toners of Examples 1 to 8 have good low temperature fixability and excellent black solid followability under high temperature and high humidity. I understand.

  The toner for electrophotography of the present invention is suitably used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (6)

An electrophotographic toner containing a binder resin and a release agent,
The binder resin is a polycondensate of an alcohol component containing an aliphatic diol having 2 to 4 carbon atoms and a carboxylic acid component containing an aromatic dicarboxylic acid compound, and has a number average molecular weight of 4,000 or more. Containing 60% by mass or more of amorphous polyester,
An electrophotographic toner in which the release agent contains a synthetic ester wax.   The toner for electrophotography according to claim 1, wherein the content of the synthetic ester wax is 30% by mass or more in the release agent.   The electrophotographic toner according to claim 1, wherein the content of the release agent is 0.1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the binder resin. Amorphous polyester
Step 1A: Step of polycondensing an alcohol component and a carboxylic acid component until the reaction rate reaches 70% or more and 99% or less, and Step 2A: an organic compound further having a sulfo group on the polycondensate obtained in Step 1A The toner for electrophotography according to any one of claims 1 to 3, which is obtained by a method including a step of adding polycondensation and polycondensation.   The electrophotographic toner according to claim 4, wherein the organic compound having a sulfo group is an aromatic compound having a sulfo group or an aliphatic compound having a sulfo group.   The electrophotographic toner according to claim 5, wherein the aromatic compound having a sulfo group is an alkylbenzene sulfonic acid having an alkyl group having 1 to 22 carbon atoms.