JP5015743B2 - Method for producing release agent dispersion for toner - Google Patents

Description

  The present invention relates to a method for producing an electrophotographic toner used in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and a method for producing a release agent dispersion for use therein.

In the field of electrophotographic toner, with the development of an electrophotographic system, development of a toner corresponding to high image quality and high speed is required. From the viewpoint of high image quality, it is necessary to reduce the particle size of the toner, and so-called chemical toners obtained by a chemical method such as a polymerization method or an emulsification dispersion method instead of the conventional melt-kneading method are disclosed. Furthermore, from the viewpoint of speeding up, it has been proposed to internally add a release agent to the toner in order to improve low-temperature fixability.
As a toner using such a release agent, for example, a toner containing a release agent that is a hydrocarbon wax treated with a binder resin, a colorant, and a styrene monomer is disclosed (Patent Document 1) or As a method for improving the toner fixing performance, a method of adding a carbodiimide compound to emulsified particles polycondensed in water to form a chemical bond on the particle surface is disclosed (Patent Document 2).

JP 2004-21112 A JP 2006-317715 A

However, in the method described in the above-mentioned patent document, since the release agent is released from the toner composition during the production of the toner, the obtained toner does not contain the desired release agent amount. Further, there arises a problem that the toner fixing property and offset resistance are not sufficient.
The present invention relates to a method for producing an electrophotographic toner that suppresses release of a release agent from a toner composition and is excellent in low-temperature fixability and offset resistance when producing a toner, and a mold release used in the method. The present invention relates to an agent dispersion and a method for producing the same.

The present invention
(1) Toner containing release agent particles having a step of mixing a dispersion of a release agent having a carboxyl group and an acid value of 0.5 to 20 mg KOH / g and a polymer having an oxazoline group A method for producing a mold release agent dispersion,
(2) A release agent dispersion for toner obtained by the production method of (1) above,
(3) While mixing the release agent dispersion liquid for toner containing the release agent particles obtained by the production method of (1) above and the dispersion liquid of resin particles containing a resin having a carboxyl group, A method for producing an electrophotographic toner comprising the step (A) of aggregating mold agent particles and resin particles, and the step (B) of coalescing the aggregated particles obtained in the step (A); An electrophotographic toner obtained by the production method of (3),
About.

  According to the production method of the present invention, the release agent particles can be prevented from being released from the toner composition during toner preparation, and an electrophotographic toner excellent in low-temperature fixability and offset resistance can be provided.

According to the production method of the present invention, the compound containing a functional group capable of reacting with each of the resin and the release agent is mixed with the release agent in advance, and then the obtained release agent particles and the resin dispersion particles are combined. By aggregating and coalescing, release of the release agent particles from the toner composition at the time of toner preparation can be prevented, and an electrophotographic toner excellent in low-temperature fixability and offset resistance can be provided.
[Toner release agent dispersion and method for producing the same]
The method for producing a release agent dispersion for toner of the present invention is a dispersion of a release agent having a carboxyl group and an acid value of 0.5 to 20 mg KOH / g (hereinafter referred to as “release agent dispersion stock solution”). And a polymer having an oxazoline group (hereinafter sometimes referred to as an “oxazoline group-containing polymer”).

As the mold release agent having a carboxyl group used in the present invention, its acid value is
From the viewpoint of reactivity with a polymer having an oxazoline group, it is 0.5 to 20 mgKOH / g, preferably 0.5 to 17 mgKOH / g, more preferably 1.0 to 15 mgKOH / g. . Specifically, acid-modified polyolefin wax, carnauba wax, rice wax, candelilla wax obtained by carboxylic acid modification of polyolefin such as ester wax having natural or synthetic long chain aliphatic group, acid-modified polyethylene wax, etc. Among them, carnauba wax is preferable from the viewpoint of low-temperature fixability and high-temperature offset resistance of the toner. In the present invention, a release agent having two or more kinds of carboxyl groups may be used in combination.
The melting point of the release agent having a carboxyl group is preferably from 50 to 100 ° C., more preferably from 70 to 95 ° C., from the viewpoints of low-temperature fixability, offset resistance, chargeability, and durability of the toner. Melting | fusing point can be measured using a differential scanning calorimeter, and can be specifically measured by the method mentioned later.

  The release agent-dispersed stock solution having a carboxyl group in the present invention is obtained by dispersing the release agent having a carboxyl group in a medium such as an aqueous medium. Specifically, the release agent is dispersed in, for example, an aqueous medium in the presence of a surfactant and heated to a temperature higher than the melting point of the release agent, and has a strong shearing force, a pressure discharge type It can be dispersed in fine particles by a homogenizer, an ultrasonic disperser, or the like, and a dispersion of release agent particles having a volume median particle size (D50) of preferably 1 μm or less can be obtained.

As the aqueous medium used for dispersing the release agent, an aqueous medium used for emulsification of the resin described later can be used. However, from the viewpoint of environmental properties and ease of addition during toner preparation, deionization is possible. Water and distilled water are preferred.
As the surfactant used in the preparation of the release agent dispersion stock solution, any of various known anionic, cationic and nonionic surfactants can be used. From the viewpoint of improving the emulsion stability, anionic surfactants such as anionic and cationic are preferable. The addition amount of the surfactant is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 7 parts per 100 parts by weight of the release agent having a carboxyl group, from the viewpoint of improving the emulsion stability. Part by weight, more preferably 0.5 to 5 parts by weight.

The solid content concentration of the release agent having a carboxyl group at the time of dispersion of the release agent dispersion stock solution is preferably 5 to 40% by weight, more preferably 10 to 35% by weight from the viewpoints of emulsification and productivity. More preferred is weight percent.
From the viewpoint of dispersibility in the toner, the volume median particle size (D50) of the release agent particles having a carboxyl group in the release agent dispersion stock solution is preferably 1 μm or less, more preferably 0.01. It is -0.9 micrometer, More preferably, it is 0.05-0.8 micrometer.

The release agent dispersion for toner containing the release agent particles of the present invention is prepared by mixing the release agent dispersion stock solution having a carboxyl group and the oxazoline group-containing polymer, specifically, It is obtained by adding an oxazoline group-containing polymer to the release agent dispersion stock solution.
As the oxazoline group-containing polymer, those containing a plurality of oxazoline groups in the molecule can be used, and among them, a polymer compound having an oxazoline group is preferably used from the viewpoint of improving reactivity with a resin having a carboxyl group. It is done. Specifically, the oxazoline group-containing polymer can be obtained from a polymerizable monomer having an oxazoline group, and if necessary, a polymerizable monomer having an oxazoline group and a copolymerizable copolymer with the polymerizable monomer. It can also be obtained by copolymerization with a functional monomer. Here, the polymerizable monomer copolymerizable with the polymerizable monomer having an oxazoline group includes both a polymerizable monomer having an oxazoline group and a polymerizable monomer having no oxazoline group. be able to.

  The polymerizable monomer having an oxazoline group is not particularly limited, and examples thereof include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2- Oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, etc. Is mentioned. These may be used alone or in combination of two or more. Among these, 2-isopropenyl-2-oxazoline is preferable because it is easily available industrially.

  Among the polymerizable monomers copolymerizable with the polymerizable monomer having an oxazoline group, the polymerizable monomer not having an oxazoline group is not particularly limited. For example, methyl (meth) acrylate, (Meth) acrylic acid ethyl, (meth) acrylic acid n-butyl, (meth) acrylic acid isobutyl, (meth) acrylic acid t-butyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid-2-ethylhexyl, ( (Meth) acrylic acid methoxypolyethylene glycol, (meth) acrylic acid lauryl, (meth) acrylic acid stearyl, (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, (meth) acrylic acid and Monoesterified product with polyethylene glycol, 2-aminoethyl (meth) acrylate and salts thereof, ( A) caprolactone-modified products of acrylic acid, (meth) acrylic acid-2,2,6,6-tetramethylpiperidine, (meth) acrylic acid-1,2,2,6,6-pentamethylpiperidine ) Acrylic acid esters; (Meth) acrylates such as sodium (meth) acrylate, potassium (meth) acrylate, ammonium (meth) acrylate; unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth) acrylamide, Unsaturated amides such as N-methylol (meth) acrylamide and N- (2-hydroxyethyl) (meth) acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; Ethylene, propylene and the like Α-olefin of vinyl chloride, vinyl chloride Halogen-containing α, β-unsaturated aliphatic hydrocarbons such as den and vinyl fluoride; α, β-unsaturated aromatic hydrocarbons such as styrene, divinylbenzene, α-methylstyrene, sodium styrenesulfonate, etc. Can do.

The content of the oxazoline group in the oxazoline group-containing polymer is preferably 0.0001 to 0.01 mol / g (in terms of oxazoline value, 100 to 10,000 g / equivalent) from the viewpoint of improving the crosslinking rate. Preferably it is 0.0005-0.01 mol / g (100-2,000 g / equivalent by an oxazoline number).
As a commercially available product generally used as the oxazoline group-containing polymer, EPOCROSS WS series (water-soluble type), K series (emulsion type) manufactured by Nippon Shokubai Co., Ltd. can be used.
The number average molecular weight of the oxazoline group-containing polymer is not particularly limited, but is preferably 500 to 2,000,000, and preferably 1,000 to 1,000 from the viewpoint of improving the crosslinking rate and handling convenience. Is more preferable. If the number average molecular weight is 500 or more, sufficient crosslinking reaction with the release agent particles or resin particles is performed. If the number average molecular weight is 2,000,000 or less, the viscosity of the polymer becomes an appropriate value and handling is possible. It becomes easy.

The oxazoline group-containing polymer is added after preparing the above release agent dispersion stock solution.
In the present invention, when the release agent dispersion stock solution and the oxazoline group-containing polymer are mixed, the oxazoline group-containing polymer and the release agent are mixed with the oxazoline group-containing polymer and the release agent dispersion stock solution. It is preferable to perform the process at a temperature of room temperature or higher. By mixing at such a temperature, the oxazoline group-containing polymer and the release agent are considered to react and bond. From the viewpoint of advancing the reaction, the mixing step is preferably performed at a temperature within the system at a temperature 20 ° C. lower than the melting point of the release agent having a carboxyl group, more preferably a release agent having a carboxyl group. Above the melting point. In particular, in the present invention, it is preferable that the temperature is at least when the release agent dispersion stock solution is mixed with the oxazoline group-containing polymer. In the present invention, since the release agent is preferably dispersed in the aqueous medium, the heating temperature is substantially equal to or lower than the boiling point of the aqueous medium, preferably 98 ° C. or lower, in the system.

  The addition amount of the oxazoline group-containing polymer can be appropriately selected based on a release agent having a carboxyl group or an acid value of a resin having a carboxyl group, but from a binder resin or toner containing a resin having a carboxyl group. From the viewpoint of prevention of liberation, the number of moles of oxazoline groups in the oxazoline group-containing polymer is at least 0.1 times the number of moles of carboxyl groups of the release agent in the release agent dispersion (b). The amount is preferably 0.2 times or more, more preferably 0.5 times or more. The number of moles of oxazoline groups in the oxazoline group-containing polymer is preferably 10 times or less, more preferably 8 times or less, relative to the number of moles of carboxyl groups in the release agent. An amount that is 5 times or less is more preferable.

The content of the release agent derived from the release agent having a carboxyl group in the toner release agent dispersion is the same as in the case of the release agent dispersion stock solution.
The toner release agent particles in the toner release agent dispersion containing the obtained oxazoline group-containing polymer are an oxazoline group-containing polymer, a release agent particle having a carboxyl group, and an oxazoline group-containing polymer and a carboxyl. It is considered to include release agent particles and the like which are bonded by reaction with a release agent having a group.

  The toner release agent dispersion containing the above-mentioned oxazoline group-containing polymer is mixed with a dispersion of resin particles obtained by dispersing a resin having a carboxyl group as described later, and a flocculant is added. , Agglomerated particles are obtained by agglomeration, and coalescence particles are obtained by heating. The reason why the low-temperature fixability and the offset resistance of the toner are improved by using the toner release agent dispersion of the present invention is that the toner existing in the toner release agent dispersion in the agglomeration and coalescence process is not present. The reaction oxazoline group reacts with a resin having a carboxyl group, which will be described later, or a release agent having an unreacted carboxyl group, and the polymer having an oxazoline group crosslinks the release agent and the resin. This is presumably because release of the release agent from the toner composition is suppressed. Here, the toner composition means one containing any one of the agglomerated particles, coalesced particles and toner particles described later.

[Method for producing toner for electrophotography]
The method for producing an electrophotographic toner of the present invention comprises mixing a release agent dispersion liquid for toner containing the release agent particles and a dispersion liquid of resin particles containing a resin having a carboxyl group, and releasing the mold. A step (A) of aggregating the agent particles and the resin particles, and a step (B) of uniting the aggregated particles obtained in the step (A).

(Process (A))
The dispersion of resin particles containing a resin having a carboxyl group is preferably obtained by emulsifying a resin containing polyester in an aqueous medium.
Resin having a carboxyl group The resin having a carboxyl group preferably contains polyester from the viewpoints of toner fixability and durability. The polyester is preferably one containing a structural unit derived from a trivalent or higher polyvalent carboxylic acid, that is, one containing a branched polyester having a branched structure. The content of the polyester is preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, and substantially 100% by weight in the resin having a carboxyl group, from the viewpoint of toner fixability and durability. % Is more preferable. The polyester may be a crystalline polyester or an amorphous polyester.

  Examples of the resin other than the polyester contained in the resin containing a carboxyl group-containing resin include known resins used for toner, such as styrene-acrylic copolymer, epoxy resin, polycarbonate, polyurethane and the like.

As a raw material monomer for polyester, a known alcohol component and a carboxylic acid component such as a carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid ester are all used.
Specific examples of the alcohol component include alkylenes of bisphenol A such as polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane ( Carbon number 2-3) oxide (average addition mole number 1-16) adduct, hydrogenated bisphenol A, ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,3-butanediol, 1, Divalent alcohols such as 6-hexanediol or their alkylene (2 to 4 carbon) oxide (average number of added moles 1 to 16) adducts; glycerin, pentaerythritol, trimethylolpropane, sorbitol or their alkylene ( 2 to 4 carbon atoms) oxide (average number of moles added) Trihydric or higher alcohol component, such as to 16) adducts. You may use the said alcohol individually or in combination of 2 or more types.

  Specific examples of the carboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, fumaric acid, maleic acid, adipic acid, azelaic acid, succinic acid, cyclohexanedicarboxylic acid and other dicarboxylic acids, dodecyl succinic acid, dodecenyl succinic acid. Divalent carboxylic acids such as succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms such as acid and octenyl succinic acid; trimellitic acid and 2,5,7-naphthalene tricarboxylic acid , Trivalent or higher polyvalent carboxylic acids such as pyromellitic acid, acid anhydrides thereof, and alkyl (1 to 3 carbon atoms) esters thereof, and the like. From the viewpoint, an aromatic polyvalent carboxylic acid is preferable. The above carboxylic acids may be used alone or in combination of two or more.

In the present invention, a trivalent or higher carboxylic acid component or a trivalent or higher alcohol component is preferably used as the raw material monomer component, and more preferably both a trivalent or higher carboxylic acid component and an alcohol component are used.
From the viewpoint of effectively forming a crosslinked structure, the carboxylic acid component as the raw material monomer preferably contains 1% by weight or more of a trivalent or higher carboxylic acid, more preferably 2% by weight or more, and more preferably 3% by weight. The above is more preferable. The content is preferably 80% by weight or less, more preferably 50% by weight or less, and further preferably 40% by weight or less. Therefore, the proportion of structural units derived from trivalent or higher carboxylic acid in the polyester is also preferably equivalent to the proportion of trivalent or higher carboxylic acid in the carboxylic acid component.

The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of about 180 to 250 ° C. in an inert gas atmosphere using an esterification catalyst as necessary.
As the esterification catalyst, an esterification catalyst such as a tin compound such as dibutyltin oxide or tin dioctylate or a titanium compound such as titanium diisopropylate bistriethanolamate can be used. The amount of the esterification catalyst used is preferably 0.01 to 1 part by weight, more preferably 0.1 to 0.6 part by weight, based on 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component.

  In the present invention, the polyester includes not only unmodified polyester but also polyester modified to such an extent that the properties are not substantially impaired, but in the present invention, it is an unmodified polyester. It is preferable. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more kinds of resin units including a polyester unit.

From the viewpoint of low-temperature fixability, offset resistance and storage stability of the toner, the softening point of the polyester is preferably 70 to 165 ° C, and the glass transition point is preferably 50 to 85 ° C. The polyester has a carboxyl group, and the acid value thereof is preferably 6 to 35 mgKOH / g, more preferably 10 to 35 mgKOH / g, and more preferably 15 to 35 mgKOH / g, from the viewpoint of manufacturability when emulsifying. Is more preferable. The desired softening point and acid value can be obtained by adjusting the condensation polymerization temperature, reaction time, and the like.
From the viewpoint of the durability of the toner, the number average molecular weight of the polyester is preferably 1,000 to 50,000, more preferably 1,000 to 10,000, and still more preferably 2,000 to 8,000.
These polyesters may be used individually by 1 type, and may be used in combination of 2 or more type.

In addition, when the resin having a carboxyl group contains a plurality of resins, the softening point, glass transition point, acid value, and number average molecular weight of the resin mean each value as a mixture of each resin, and each value Is preferably the same value as that of the polyester.
Further, the above-mentioned resin can contain two kinds of polyesters having different softening points from the viewpoint of low-temperature fixability, offset resistance and durability of the toner, and the softening point of one polyester (A) is 70 or more and 115. The softening point of the other polyester (b) is preferably 115 ° C. or higher and 165 ° C. or lower. The weight ratio (I / B) between the polyester (A) and the polyester (B) is preferably 10/90 to 90/10, more preferably 50/50 to 90/10.

Dispersion of Resin Particles Containing Resin Having Carboxyl Group The dispersion of the resin having a carboxyl group can be carried out by dispersing a resin having a carboxyl group, preferably a resin containing polyester, in an aqueous medium.
The aqueous medium in which the resin is dispersed is mainly composed of water. From the viewpoint of environmental properties, the content of water in the aqueous medium is preferably 80% by weight or more, more preferably 95% by weight or more, and still more preferably 100% by weight.
Examples of components other than water include alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, and organic solvents that dissolve in water such as acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, the alcohol-based organic solvent that is an organic solvent that does not dissolve the resin is preferable from the viewpoint of preventing mixing into the toner. In the present invention, it is preferable to atomize the resin using only water without substantially using an organic solvent.

In the present invention, first, resin particles containing a carboxyl group-containing resin, preferably polyester, are prepared in an aqueous medium. The resin dispersion containing the resin particles is prepared by reducing the particle size of the resin particles. From the viewpoint of uniform particle size distribution of the obtained toner, it is preferable to emulsify the resin.
The resin particles in the resin dispersion obtained by dispersing the resin in the aqueous medium may contain other resins, colorants, charge control agents, fibrous substances, etc. Additives such as reinforcing fillers, antioxidants, anti-aging agents and the like can be included.
The content of the resin having a carboxyl group in the total resin constituting the toner (also referred to as a binder resin) is 70% by weight from the viewpoint of reactivity with a polymer having an oxazoline group, low-temperature fixability, and offset resistance. % Or more is preferable, 80% by weight or more is more preferable, 90% by weight is further preferable, and substantially 100% by weight is particularly preferable.
In addition, the acid value of the total binder resin is preferably the same as the acid value of the resin having a carboxyl group from the viewpoint of reactivity with the polymer having an oxazoline group, that is, from the viewpoint of suppressing release of the release agent.

The colorant is not particularly limited, and any known colorant can be used. Specifically, carbon black, inorganic composite oxide, chrome yellow, hansa yellow, benzidine yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, brilliantamine 6B, dupont oil Various pigments such as red, rhodamine B lake, lake red C, Bengal, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, acridine, azo, benzoquinone, azine, anthraquinone 1 type of various dyes such as azoind, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane, and xanthene Alone or in combination of two or more can be used.
The content of the colorant is preferably 20 parts by weight or less, more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

Examples of charge control agents include metal salts of benzoic acid, metal salts of salicylic acid, metal salts of alkyl salicylic acid, metal salts of catechol, metal-containing (chromium, iron, aluminum, etc.) bisazo dyes, tetraphenylborate derivatives, quaternary Examples thereof include ammonium salts and alkylpyridinium salts.
The content of the charge control agent is preferably 10 parts by weight or less, and more preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

In the present invention, when dispersing the resin having a carboxyl group, from the viewpoint of improving the emulsion stability of the resin, the amount is preferably 10 parts by weight or less, more preferably 5 parts by weight with respect to 100 parts by weight of the binder resin. In the following, it is more preferable that 0.1 to 3 parts by weight, and still more preferably 0.5 to 2 parts by weight of a surfactant is present.
Examples of the surfactant include anionic surfactants such as sulfate ester type, sulfonate type, phosphate ester type, and soap type; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene Nonionic surfactants such as glycol-based, alkylphenol ethylene oxide adduct-based, polyhydric alcohol-based and the like can be mentioned. Among these, ionic surfactants such as anionic surfactants and cationic surfactants are preferable. The nonionic surfactant is preferably used in combination with an anionic surfactant or a cationic surfactant. Although the said surfactant may be used individually by 1 type, you may use it in combination of 2 or more type.

Specific examples of the anionic surfactant include dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium alkyl ether sulfate, sodium alkyl naphthalene sulfonate, sodium dialkyl sulfosuccinate and the like. Among these, sodium dodecylbenzenesulfonate is preferable.
Specific examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like.

  Nonionic surfactants include, for example, polyoxyethylene nonylphenyl ether, polyoxyethylene alkyl aryl ethers such as polyoxyethylene oleyl ether or polyoxyethylene alkyl ethers, polyoxyethylene sorbitan monolaurate, polyoxyethylene And polyoxyethylene sorbitan esters such as ethylene sorbitan monostearate, polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, and oxyethylene / oxypropylene block copolymers.

  The resin particles in the resin dispersion further contain another releasing agent within the range not impairing the effects of the present invention, together with the releasing agent derived from each of the releasing agent dispersion or the releasing agent stock solution. be able to. Other mold release agents include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide and stearic acid amide; carnauba wax, rice wax, can Plant waxes such as delilla wax, tree wax, jojoba oil; animal waxes such as beeswax; mineral and petroleum waxes such as montan wax, ozokerite, ceresin, paraffin wax, and Fischer-Tropsch wax, but release agents From the viewpoint of inhibiting release, it is preferable that no other release agent is contained in the resin dispersion.

In the dispersion, it is preferable to add an alkaline aqueous solution to the resin and disperse the resin and additives used as necessary.
The alkaline aqueous solution preferably has a concentration of 1 to 20% by weight, more preferably 1 to 10% by weight, and still more preferably 1.5 to 7.5% by weight. As for the alkali to be used, it is preferable to use an alkali that enhances the surface activity when the polyester becomes a salt. Specific examples thereof include monovalent alkali metal hydroxides such as potassium hydroxide and sodium hydroxide.
After dispersion, the resin particle dispersion can be produced by neutralizing at a temperature above the glass transition point of the resin and then emulsifying by adding an aqueous medium at a temperature above the glass transition point.

The addition rate of the aqueous medium is preferably from 0.1 to 50 g / min, more preferably from 0.5 to 40 g / min, and even more preferably from 1 to 30 g / min per 100 g of the resin from the viewpoint that emulsification can be effectively carried out. min. This addition rate is generally maintained until an O / W type emulsion is substantially formed, and there is no particular limitation on the addition rate of water after the formation of the O / W type emulsion.
Examples of the aqueous medium used for the production of the resin particle dispersion include the same as the above-mentioned aqueous medium, and preferably deionized water or distilled water.
The amount of the aqueous medium is preferably 100 to 2,000 parts by weight and more preferably 150 to 1,500 parts by weight with respect to 100 parts by weight of the resin from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation step. From the viewpoint of stability and handleability of the resulting dispersion, the solid content concentration of the resin particle dispersion is preferably 7 to 50% by weight, more preferably 7 to 40% by weight, and still more preferably 10 to 30% by weight. The amount of the aqueous medium is selected so that In addition, non-volatile components, such as resin and a nonionic surfactant, are contained in solid content.

Further, the temperature at this time is preferably in the range of not less than the glass transition point and not more than the softening point of the resin from the viewpoint of preparing a fine resin particle dispersion. By carrying out the emulsification at a temperature within the above range, the emulsification is carried out smoothly and no special apparatus is required for heating. From this point, the temperature is preferably equal to or higher than the (glass transition point + 10 ° C.) of the resin (meaning “temperature higher by 10 ° C. than the glass transition point”, hereinafter the same notation is similarly understood). , (Softening point −5 ° C.) or less.
The volume median particle size (D50) of the resin particles in the resin particle dispersion thus obtained is preferably 0.02 to obtain aggregated particles having a uniform particle size in the subsequent aggregation step. It is 2 μm, more preferably 0.05 to 1 μm, still more preferably 0.05 to 0.6 μm. Here, “volume median particle size (D50)” means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

As another method of emulsifying a resin in an aqueous medium to obtain a resin emulsion, for example, first, a polycondensable monomer is used as an objective resin particle raw material in an aqueous medium, for example, mechanical share or ultrasonic waves. And the like. At this time, if necessary, additives such as a polycondensation catalyst and a surfactant are also added to the water-soluble medium. And polycondensation is advanced by, for example, heating the solution. For example, when the resin is polyester, the above-mentioned polyester polycondensable monomer and polycondensation catalyst can be used, and the above-mentioned surfactants can be used similarly.
Usually, polycondensation resins do not proceed in an aqueous medium in principle because they are dehydrated during polymerization. However, for example, when a polycondensable monomer is emulsified in an aqueous medium together with a surfactant that causes micelles to form in the aqueous medium, the monomer is placed in a micro hydrophobic field in the micelle. Then, dehydration occurs, and the generated water can be discharged into an aqueous medium outside the micelles to allow polymerization to proceed. In this way, a dispersion in which polycondensation resin particles are emulsified and dispersed in an aqueous medium is obtained with low energy.

Aggregation Step In the present invention, the toner release agent particles in the toner release agent dispersion and the resin particles in a resin particle dispersion containing a resin containing a carboxyl group-containing resin are aggregated. That is, the obtained resin dispersion is mixed with the toner release agent dispersion and aggregated by adding an aggregating agent to obtain aggregated particles.
The ratio of the release agent particles derived from the release agent having a carboxyl group and the resin particles containing a resin having a carboxyl group in the toner release agent dispersion has an adverse effect on the addition effect and the chargeability of the toner. In consideration, the particle derived from the release agent having a carboxyl group in the toner release agent dispersion is usually about 1 to 20 parts by weight, preferably 2 to 15 parts per 100 parts by weight of the resin in the resin particles. The ratio is preferably such that it is part by weight. Here, the particle derived from the release agent having a carboxyl group includes not only the release agent particles having a carboxyl group but also the release agent particles reacted with a polymer having an oxazoline group.

In the aggregating step, an aggregating agent is added to effectively agglomerate. In the present invention, as an aggregating agent, a quaternary salt cationic surfactant, polyethyleneimine or the like is used in an organic system, and an inorganic metal salt, an inorganic ammonium salt, a divalent or higher metal complex, or the like is used in an inorganic system. Examples of inorganic metal salts include metal salts such as sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, polyaluminum chloride, polyaluminum hydroxide, Examples thereof include inorganic metal salt polymers such as calcium sulfide. Examples of the inorganic ammonium salt include ammonium sulfate, ammonium chloride, and ammonium nitrate.
Of the aggregating agents, monovalent salts are preferably used from the viewpoint of achieving highly accurate toner particle size control and a sharp particle size distribution. Here, the monovalent salt means that the valence of the metal ion or cation constituting the salt is 1. As the monovalent salt, organic flocculants such as quaternary salt cationic surfactants and inorganic flocculants such as inorganic metal salts and ammonium salts are used. In the present invention, water-soluble water having a molecular weight of 350 or less is used. A nitrogen-containing compound is preferably used.

  The water-soluble nitrogen-containing compound having a molecular weight of 350 or less is preferably a compound exhibiting acidity from the viewpoint of rapidly agglomerating primary particles, and a 10% by weight aqueous solution having a pH value of 4 to 6 at 25 ° C. Are preferable, and 4.2 to 6 are more preferable. Examples of such water-soluble nitrogen-containing compounds include ammonium salts such as ammonium halide, ammonium sulfate, ammonium acetate, ammonium benzoate and ammonium salicylate, and quaternary ammonium salts such as tetraalkylammonium halide. From the viewpoint of properties, ammonium sulfate (pH value of a 10 wt% aqueous solution at 25 ° C., hereinafter referred to as pH value: 5.4), ammonium chloride (pH value: 4.6), tetraethylammonium bromide (pH value: 5. 6) and tetrabutylammonium bromide (pH value: 5.8) are preferred.

  The amount of the flocculant used is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, with respect to 100 parts by weight of the binder resin, from the viewpoint of toner charging properties, particularly charging characteristics in a high temperature and high humidity environment. More preferred are parts by weight or less. Moreover, from a cohesive viewpoint, 1 weight part or more is preferable with respect to 100 weight part of resin, 3 weight part or more is more preferable, and 5 weight part or more is still more preferable. Considering the above points, the amount of monovalent salt used is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight, and still more preferably 5 to 30 parts by weight with respect to 100 parts by weight of the resin.

The addition of the flocculant is performed after adjusting the pH in the system, and then the temperature of the resin (glass transition point + 20 ° C.) or less, preferably (glass transition point + 10 ° C.) or less, more preferably (glass transition point + 5 ° C.). ) At a temperature below. By carrying out at the said temperature, a particle size distribution is narrow and uniform agglomeration can be performed. The addition is preferably performed at (softening point−100 ° C.) or more of the resin, and more preferably (softening point−90 ° C.) or more. In this case, the pH in the system is preferably 2 to 10, more preferably 2 to 8, and further preferably 3 to 7 from the viewpoint of achieving both the dispersion stability of the mixed solution and the cohesiveness of the resin particles.
The flocculant can be added as an aqueous medium solution. The flocculant may be added at one time, or may be added intermittently or continuously. Furthermore, it is preferable to sufficiently stir at the time of adding the monovalent salt and after the addition is completed.

In this way, aggregated particles are prepared by aggregating the release agent particles for toner and the resin particles in the resin dispersion.
The aggregated particles preferably have a volume median particle size (D50) of 1 to 10 μm, more preferably 2 to 9 μm, and still more preferably 2 to 6 μm, from the viewpoint of reducing the particle size.

In the present invention, it is preferable to add a surfactant after aggregating dispersed particles, and at least one selected from the group consisting of alkyl ether sulfates, alkyl sulfates, and linear alkylbenzene sulfonates is added. More preferably.
The amount of the surfactant added is preferably from 0.1 to 15 parts by weight, more preferably from 0.1 to 15 parts by weight, based on 100 parts by weight of the resin constituting the aggregated particles, from the viewpoints of aggregation stopping properties and persistence to the toner. 1 to 10 parts by weight, more preferably 0.1 to 8 parts by weight.
The obtained aggregated particles are subjected to a step (unification step) for coalescing the aggregated particles in step (B).

(Process (B))
Step (B) is a step of coalescing the aggregated particles including the release agent particles and resin particles obtained in step (A).
In the present invention, the aggregated particles obtained in the aggregation step are heated and united. In the coalescence process, the temperature in the system is preferably equal to or higher than the temperature in the system in the aggregation process, but the target toner particle size, particle size distribution, shape control, and particle fusing property In view of the above, the glass transition point or higher of the resin is preferable, (softening point + 20 ° C) or lower is more preferable, (glass transition point + 5 ° C) or higher and (softening point + 15 ° C) or lower is more preferable, (glass transition point + 10 ° C). ) And more preferably (softening point + 10 ° C.) or less. The stirring speed is preferably a speed at which the aggregated particles do not settle.
In the present invention, the coalescence step may be performed simultaneously with the aggregation step, for example, by continuously raising the temperature or by raising the temperature to a temperature at which aggregation and coalescence can be performed and then continuing stirring at that temperature. it can.
From the viewpoint of high image quality, the volume-median particle size (D50) of the coalesced particles is preferably 1 to 10 μm, more preferably 2 to 8 μm, and even more preferably 3 to 8 μm.

  The obtained coalesced particles become toner particles through a solid-liquid separation process such as filtration, a washing process, and a drying process. Here, in order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to perform cleaning with an acid in order to remove metal ions on the toner surface in the cleaning step. Further, it is preferable to completely remove the added nonionic surfactant by washing, and washing with an aqueous solution below the cloud point of the nonionic surfactant is preferred. The washing is preferably performed a plurality of times.

  In the drying step, any method such as a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like can be employed. The water content after drying of the toner particles is preferably adjusted to 1.5% by weight or less, more preferably 1.0% by weight or less, from the viewpoint of chargeability of the toner.

[Electrophotographic toner]
The electrophotographic toner of the present invention is obtained by the above production method.
The softening point of the electrophotographic toner obtained by the present invention is preferably 105 to 200 ° C., more preferably 105 to 180 ° C., and further preferably 105 to 160 ° C. from the viewpoint of expanding the fixing temperature range. Further, the glass transition point is preferably 30 to 80 ° C., more preferably 40 to 70 ° C., from the viewpoint of improving low-temperature fixability and storage stability. The method for measuring the softening point and glass transition point of the toner is in accordance with these measurement methods for the resin.
From the viewpoint of high image quality, the volume median particle size (D50) of the toner is preferably 1 μm or more, and more preferably 2 μm or more. Moreover, 9 micrometers or less are preferable, 8 micrometers or less are more preferable, 7 micrometers or less are still more preferable, and 6 micrometers or less are especially preferable. The particle diameter of the toner particles can be measured by the method described later.

  Further, from the viewpoint of improving the transferability of the toner and expanding the fixing temperature range, the circularity of the toner is preferably 0.93 to 1.00, more preferably 0.94 to 0.99, and more preferably 0.95 to 0.99. Is more preferable. The degree of circularity can be measured by a flow type particle image analyzer, specifically by FPIA-3000 (Sysmex Corporation). In the present invention, the circularity of a particle is a value obtained by the ratio of the circumference of a circle equal to the projected area / the circumference of the projected image. The more circular the particle is, the closer the circularity is to 1.

Further, the CV values of the above-mentioned aggregated particles, coalesced particles and toner particles are all preferably 45 or less, more preferably 35 or less, and still more preferably 30 or less. The coefficient of variation (CV value) of the particle size distribution is expressed by the formula CV value = [standard deviation of particle size distribution (μm) / volume median particle size (μm)] × 100
This is an index indicating the sharpness of the particle size distribution. The smaller the value, the sharper the particle size distribution and the better the image characteristics.

The toner particles obtained as described above can be used as an electrophotographic toner, or an additive such as a fluidizing agent can be added to the toner particle surface as an external additive to obtain the electrophotographic toner of the present invention. . External additives include known fine particles such as silica fine particles, titanium fine particles, alumina fine particles, cerium oxide fine particles, carbon black and other inorganic fine particles, and polymer fine particles such as polycarbonate, polymethyl methacrylate and silicone resin. Can be used. The number average particle diameter of the external additive is preferably 4 to 200 nm, more preferably 8 to 30 nm. The number average particle diameter of the external additive is determined using a scanning electron microscope or a transmission electron microscope.
The amount of the external additive is preferably 1 to 5 parts by weight and more preferably 1.5 to 3.5 parts by weight with respect to 100 parts by weight of the toner before processing with the external additive.
The toner for electrophotography obtained by the present invention can be used as a one-component developer or as a two-component developer by mixing with a carrier.

In the following examples and the like, each property value was measured and evaluated by the following method.
[Acid value of resin]
Measured according to JIS K0070. However, the measurement solvent was a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Softening point and glass transition point of resin]
(1) Softening point Using a flow tester (Shimadzu Corporation, “CFT-500D”), a 1 g sample was heated at a heating rate of 6 ° C./min, a load of 1.96 MPa was applied by a plunger, a diameter of 1 mm, Extrude from a 1 mm long nozzle. Plot the flow tester drop by the flow tester against the temperature, and let the softening point be the temperature at which half the sample flowed out.
(2) Glass transition point Using a differential scanning calorimeter (“Pyris 6 DSC” manufactured by Parkin Elmer), the temperature was raised to 200 ° C. at 10 ° C./min, and the temperature was lowered to 0 ° C. at a temperature lowering rate of 10 ° C./min. The measured sample is measured at a heating rate of 10 ° C./min. The temperature at the intersection of the baseline extension line below the maximum peak temperature of endotherm and the tangent line showing the maximum slope from the peak rising portion to the peak apex is read as the glass transition point. The maximum peak temperature of endotherm refers to the peak temperature on the highest temperature side among the observed endothermic peak temperatures.

[Number average molecular weight of resin]
The molecular weight distribution is measured by gel permeation chromatography and the number average molecular weight is calculated by the following method.
(1) Preparation of sample solution The binder resin is dissolved in chloroform so that the concentration is 0.5 g / 100 ml. Subsequently, this solution is filtered using a fluororesin filter having a pore size of 2 μm [manufactured by Sumitomo Electric Industries, Ltd., “FP-200”] to remove insoluble components to obtain a sample solution.

(2) Measurement of molecular weight Tetrahydrofuran is allowed to flow as a solution at a flow rate of 1 ml / min, and the column is stabilized in a constant temperature bath at 40 ° C. 100 μl of the sample solution is injected therein and measurement is performed. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. In the calibration curve at this time, several types of monodisperse polystyrene (2.63 × 10 ³ , 2.06 × 10 ⁴ , 1.02 × 10 ⁵ manufactured by Tosoh Corporation), 2.10 × manufactured by GL Sciences Inc. 10 ³ , 7.00 × 10 ³ , 5.04 × 10 ⁴ ) are used as standard samples.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analysis column: GMHLX + G3000HXL (manufactured by Tosoh Corporation)

[Particle size of resin emulsified particles and toner release agent particles]
(1) Measuring apparatus: Laser scattering type particle size measuring machine (LA-920, manufactured by HORIBA, Ltd.)
(2) Measurement conditions: Distilled water is added to the measurement cell, and the volume-median particle size (D50) is measured at a temperature where the absorbance falls within an appropriate range.

[Acid value of release agent]
A sample prepared by adding a mixed solution of toluene and ethanol (toluene: ethanol = 2: 1 (volume ratio)) to 1 g of the mold release agent and adding a very small amount of 1% phenolphthalein solution as an indicator is 0.1 mol / L hydroxylated. Titrate with potassium ethanol solution. The end point is a point where a pale red color of phenolphthalein continued for 30 seconds. From the obtained titration result, the acid value was determined from the following formula.
(Acid value) = (5.611 × A × f) / (weight of release agent [g])
A: Use amount of titrated potassium hydroxide ethanol solution (mL)
f: Factor of potassium hydroxide ethanol solution [melting point and endothermic amount of release agent]
Using a differential scanning calorimeter (“Pyris 6 DSC” manufactured by Parkin Elmer), the sample was heated to 200 ° C. at 10 ° C./min, and the sample was cooled to 0 ° C. at a temperature decrease rate of 10 ° C./min. Measure at 10 ° C / min. Taking the maximum peak temperature as the melting point, the endothermic amount is determined from the area of the endothermic peak at that time. The maximum peak refers to the temperature having the highest peak intensity among the observed peak temperatures.

[Toner particle size]
-Measuring machine: Coulter Multisizer III (Beckman Coulter, Inc.)
・ Aperture diameter: 50μm
・ Analysis software: Multisizer III version 3.51 (Beckman Coulter, Inc.)
・ Electrolyte: Isoton II (Beckman Coulter)
-Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the electrolyte so as to have a concentration of 5% by weight to obtain a dispersion.
-Dispersion condition: 10 mg of a measurement sample is added to 5 mL of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, and then 25 mL of an electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. A sample dispersion is prepared.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolytic solution to adjust the particle size of 30,000 particles to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured and the particle size distribution thereof. To determine the volume-median particle size (D50).
The particle size distribution is indicated by a CV value (standard deviation of particle size distribution / volume median particle size (D ₅₀ ) × 100).

Production Example 1 [Production of Release Agent Dispersion Stock Solution a]
After dissolving 4.29 g of alkenyl (mixture of hexadecenyl group and octadecenyl group) dipotassium succinate “Latemul ASK (manufactured by Kao Corporation), effective concentration 28 wt%” in 480 g of deionized water in a 1 liter beaker. 120 g of carnauba wax (manufactured by Kato Yoko Co., Ltd., melting point 85 ° C., acid value 5 mgKOH / g) was dispersed. The dispersion was subjected to a dispersion treatment for 30 minutes with “Ultrasonic Homogenizer 600W” (manufactured by Nippon Seiki Co., Ltd.) while maintaining the temperature at 90 to 95 ° C., and then cooled to room temperature. The volume median particle size (D50) of the release agent emulsified particles was 0.435 μm, and the coefficient of variation (CV value) in the particle size distribution was 31.9. Ion exchange water was added thereto to adjust the release agent solid content to 20% by weight to obtain a release agent dispersion stock solution a.

Production Example 2 [Production of Release Agent Dispersion Stock Solution b]
In the production of the release agent dispersion A (Production Example 1), the release agent used was a synthetic ester wax WEP-8 high acid value product (manufactured by NOF Corporation, melting point 79 ° C., acid value 5 mgKOH / g). Similarly, a release agent dispersion stock solution b was obtained.

Production Example 3 [Production of Release Agent Dispersion Stock Solution c]
In the production of the release agent dispersion A (Production Example 1), the release agent to be used was the same except that synthetic ester wax WEP-3 (manufactured by NOF Corporation, melting point 83 ° C., acid value 0.1 mg KOH / g) was used. Thus, a release agent-dispersed stock solution c was obtained.

Example 1 [Production of Release Agent Dispersion A for Toner Containing Oxazoline Group-Containing Polymer]
101 g of the release agent dispersion stock solution a was heated to 90 ° C., and Epocros WS-700 (manufactured by Nippon Shokubai Co., Ltd., oxazoline group content in the oxazoline group-containing polymer: 4.55 mmol / g, number average molecular weight: 20, 000, 25% aqueous solution) 1.58 g (1.79 mmol of oxazoline group, 1.0 times the carboxyl group of the release agent) was added dropwise and stirred for 30 minutes while maintaining the temperature. After cooling to room temperature, a release agent dispersion liquid A for toner containing an oxazoline group-containing polymer was obtained.

Example 2 [Production of Release Agent Dispersion B for Toner Containing Oxazoline Group-Containing Polymer]
In a 1 liter beaker, after dissolving 4.29 g of alkenyl (a mixture of hexadecenyl group and octadecenyl group) dipotassium succinate “Latemul ASK (manufactured by Kao), effective concentration 28 wt%” in 480 g of deionized water, 120 g of carnauba wax (manufactured by Kato Yoko Co., Ltd., melting point 85 ° C.) was mixed. While maintaining the temperature at 90 to 95 ° C., this mixed solution was subjected to a dispersion treatment with “Ultrasonic Homogenizer 600W” (manufactured by Nippon Seiki Co., Ltd.) for 30 minutes to obtain a release agent dispersion stock solution d. While maintaining the temperature of the release agent dispersion stock solution d at 90 to 95 ° C., Epocros WS-700 (manufactured by Nippon Shokubai Co., Ltd., oxazoline group content in the oxazoline group-containing polymer: 4.55 mmol / g, number average) 9.48 g (molecular weight: 20,000, 25% aqueous solution) 9.48 g (oxazoline group 10.6 mmol, 1.0 times the carboxyl group of the release agent) was added dropwise and stirred for 30 minutes while maintaining the temperature. After cooling to room temperature, a release agent dispersion B for toner containing an oxazoline group-containing polymer was obtained.

Example 3 [Production of Release Agent Dispersion C for Toner Containing Oxazoline Group-Containing Polymer]
101 g of the release agent dispersion stock solution b was heated to 90 ° C., and Epocros WS-700 (manufactured by Nippon Shokubai Co., Ltd., oxazoline group content in the oxazoline group-containing polymer: 4.55 mmol / g, number average molecular weight: 20, 000, 25% aqueous solution) 1.58 g (1.79 mmol of oxazoline group, 1.0 times the carboxyl group of the release agent) was added dropwise and stirred for 30 minutes while maintaining the temperature. After cooling to room temperature, a release agent dispersion liquid C for toner containing an oxazoline group-containing polymer was obtained.

Comparative Example 1 [Production of Release Agent Dispersion D for Toner Containing Oxazoline Group-Containing Polymer]
101 g of the release agent dispersion stock solution c was heated to 90 ° C., and Epocros WS-700 (manufactured by Nippon Shokubai Co., Ltd., oxazoline group content in the oxazoline group-containing polymer: 4.55 mmol / g, number average molecular weight: 20, 000, 25% aqueous solution) 0.79 g (0.89 mmol of oxazoline group, 25 times the carboxyl group of the release agent, 1.0% by weight of release agent) was added dropwise, and the temperature was maintained for 30 minutes. While stirring. After cooling to room temperature, a release agent dispersion liquid D for toner containing an oxazoline group-containing polymer was obtained.

Comparative Example 2 [Production of Toner Release Agent Dispersion E Containing Oxazoline Group-Containing Polymer]
In a 1 liter beaker, after dissolving 4.29 g of alkenyl (a mixture of hexadecenyl group and octadecenyl group) dipotassium succinate “Latemul ASK (manufactured by Kao), effective concentration 28 wt%” in 480 g of deionized water, 120 g of carnauba wax (manufactured by Kato Yoko Co., Ltd., melting point 85 ° C.) was added, followed by Epocros WS-700 (manufactured by Nippon Shokubai Co., Ltd., oxazoline group content in the oxazoline group-containing polymer: 4.55 mmol / g, number average molecular weight) : 20,000, 25% aqueous solution) 1.58 g (oxazoline group 1.79 mmol, 1.0 times the carboxyl group of the release agent, 1.0 wt% of the release agent) was added. While maintaining this dispersion at a temperature of 90 to 95 ° C., the dispersion was subjected to a dispersion treatment with “Ultrasonic Homogenizer 600W” (manufactured by Nippon Seiki Co., Ltd.) for 30 minutes, but could not be emulsified.

Table 1 summarizes the toner release agent dispersions prepared in the above Examples and Comparative Examples.

Production Example 4 (Production of polyester A)
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 8,320 g, Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane 80 g, terephthalic acid 1,592 g and 32 g of dibutyltin oxide (esterification catalyst) were reacted at 230 ° C. under normal pressure (101.3 kPa) for 5 hours under a nitrogen atmosphere, and further reacted under reduced pressure (8.3 kPa). After cooling to 210 ° C., 1,672 g of fumaric acid and 8 g of hydroquinone were added and reacted for 5 hours, and further reacted under reduced pressure to obtain polyester A. Polyester A had a softening point of 110 ° C., a glass transition point of 66 ° C., an acid value of 24.4 mgKOH / g, and a number average molecular weight of 3,760. When 1 kg of the obtained polyester A was sieved with a sieve having an opening diameter of 5.6 mm, nothing remained on the sieve.

Production Example 5 (Production of polyester B)
Polyoxypropylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane 17,500 g, polyoxyethylene (2.0) -2, 2-bis (4-hydroxyphenyl) propane 16,250 g, 11,454 g of terephthalic acid, 1,608 g of dodecenyl succinic anhydride, 4,800 g of trimellitic anhydride and 15 g of dibutyltin oxide were put into a four-necked flask equipped with a nitrogen introducing tube, a dehydrating tube, a stirrer and a thermocouple, Under a nitrogen atmosphere, the mixture was stirred at 220 ° C. and reacted until the softening point measured according to ASTM D36-86 reached 120 ° C. to obtain polyester B. Polyester B had a softening point of 121 ° C., a glass transition point of 65 ° C., an acid value of 18.5 mgKOH / g, and a number average molecular weight of 3,394. When 1 kg of the obtained polyester B was sieved with a sieve having an opening diameter of 5.6 mm, nothing remained on the sieve.

Production Example 6 (Production of resin dispersion 1)
In a 5-liter stainless steel kettle, 390 g of polyester A, 210 g of polyester B, 30.0 g of copper phthalocyanine pigment (ECB-301, manufactured by Dainichi Seika Kogyo Co., Ltd.), nonionic surfactant (“Emulgen” manufactured by Kao Corporation) 430 "), 20.0 g of anionic surfactant (" Neopelex G-15 "sodium dodecylbenzenesulfonate 15 wt% aqueous solution manufactured by Kao Corporation), potassium hydroxide aqueous solution (neutralizing agent, concentration: 5 wt%) %) 252 g was charged and melted at 95 ° C. for 2 hours with stirring at 200 rpm with a chi-type stirrer to obtain a binder resin mixture. Next, a total of 1138 g of deionized water was added dropwise at a rate of 6 g / min while stirring at 200 rpm with a chi-type stirrer to prepare a resin dispersion. Finally, the mixture was cooled to room temperature and passed through a 200 mesh (mesh: 105 μm) wire mesh to obtain an emulsion of finely divided resin fine particles containing 29% by weight of resin. The volume median particle size (D50) of the primary particles was 0.156 μm, the coefficient of variation (CV value) in the particle size distribution was 28, and nothing remained on the wire mesh. Ion exchange water was added thereto to adjust the resin content to 23% by weight to obtain a resin emulsion 1.

Example 4 (Production of toner)
300 g of resin dispersion 1 and 18.9 g of release agent dispersion 1 containing an oxazoline group-containing polymer were mixed in a 2 liter container at room temperature. Next, under agitation at 100 rpm with a Kai-type stirrer, 145.8 g of a 10.9 wt% ammonium sulfate aqueous solution was added as a flocculant, and further stirred at room temperature for 60 minutes. Thereafter, the mixed dispersion was heated from room temperature to 55 ° C. (temperature rising rate: 0.25 ° C./min) and held at 55 ° C. for 3 hours to produce aggregated particles.

Next, 141.2 g of an aqueous solution of 0.63 wt% anionic surfactant (“Emar E27C” manufactured by Kao Co., Ltd.) was added, the temperature was raised to 80 ° C. (temperature raising rate: 1 ° C./min), and held for 1 hour. To obtain coalesced particles. The obtained coalesced particles were cooled to room temperature, and then toner mother particles were obtained through a suction filtration step, a washing step, and a drying step.
To 100 parts by weight of the toner base particles, 2.5 parts of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd .; RY50, average particle size; 0.04 μm), hydrophobic silica (manufactured by Cabot; Cabo Seal TS720, average particle size; 0.012 μm) was externally added with a Henschel mixer, and the fine particles that passed through a 150 mesh sieve were used as cyan toner. The volume median particle size of the toner was 5.0 μm and the CV value was 25.

Examples 5 and 6 and Comparative Examples 3 and 4
Each cyan toner was prepared in the same manner as in Example 4 except that the release agent dispersion A containing the oxazoline group-containing polymer was changed as shown in Table 2. In Comparative Example 3, the release agent dispersion stock solution a of Production Example 1 was used in place of the release agent dispersion A of Example 4.

With respect to the cyan toners obtained in each of the above Examples and Comparative Examples, release agent release evaluation, low-temperature fixability evaluation, and hot offset resistance evaluation were performed by the following methods. The results are shown in Table 2.

[Evaluation of release of release agent from toner]
The toner particle dispersion liquid after the visual evaluation coalescence process and before the solid-liquid separation process (filtration process) was sampled and observed with a microscope. Further, the sampled toner particle dispersion was allowed to stand, and the turbidity of the supernatant was confirmed. When there is no release of the release agent, the supernatant is colorless and transparent, but when there is release of the release agent, it can be confirmed that the supernatant becomes cloudy.

From the ratio of the endothermic peak of the endothermic peak derived from the release agent obtained by measuring the release agent content toner in the toner with a differential scanning calorimeter and the endothermic value measured by the release agent alone, Obtained by the formula.
Release agent content (%) = [(Endothermic amount derived from release agent in toner) / (Endothermic amount of release agent alone)] × 100
Here, the endothermic amount derived from the release agent in the toner is the endothermic amount in the toner observed at the endothermic peak temperature observed when the release agent alone is measured, and the endothermic amount of the release agent is measured. Measure in the same manner as above.

[Evaluation of low temperature fixability and hot offset resistance of toner]
Using a commercially available printer (Oki Data, “ML5400”) on high-quality paper (Fuji Xerox Co., Ltd., J paper A4 size), the toner adhesion amount on the paper is 0.45 ± 0.03 mg / cm ^A solid image of ² was output as an unfixed image with a length of 50 mm, leaving a margin of 5 mm from the top edge of A4 paper. The fixing device mounted on the printer was modified to have a variable temperature, and fixed at a temperature fixing speed of 34 sheets / minute (A4 vertical direction). The fixability of the obtained fixed image was evaluated by the following tape peeling method.

Cut the mending tape (3M Scotch Mending Tape 810 width 18mm) to 50mm in length and lightly attach it to the margin at the top of the fixed image, and then place a 500g weight on it at a speed of 10mm / sec. Pushed back and forth. Thereafter, the applied tape was peeled off from the lower end side at a peeling angle of 180 degrees and a speed of 10 mm / sec, the reflection image density before and after tape application was measured according to the measurement method, and the fixing rate was calculated from the following formula.
Fixing rate = (image density after tape peeling / image density before tape application) × 100
When the image density after peeling the tape becomes the same value as the image density before sticking the tape, the fixing rate is 100. As the value becomes smaller, the fixing property is lower. When the fixing rate is 90 or more, the fixing property is good.

  The above test is performed at each fixing temperature in increments of 5 ° C., and the test is performed from a temperature at which a cold offset occurs or a temperature at which the fixing rate is less than 90 to a temperature at which a hot offset occurs. The cold offset refers to a phenomenon in which the toner on the unfixed image does not melt sufficiently when the fixing temperature is low, and the toner adheres to the fixing roller. On the other hand, the hot offset refers to a high fixing temperature. In this case, the phenomenon is that the toner adheres to the fixing roller due to a decrease in the viscoelasticity of the toner on the unfixed image. The occurrence of cold offset or hot offset can be judged again by whether toner adheres to the paper when the fixing roller makes one round. In this test, whether toner adheres to the area 87 mm from the top of the solid image. Judged by no. Here, the minimum fixing temperature refers to the minimum temperature among the temperatures at which a cold offset does not occur or the fixing rate is 90 or more.

  According to the present invention, the release agent can be prevented from being released from the toner, and a toner excellent in fixing property and hot offset resistance can be obtained. Therefore, the toner obtained by the production method of the present invention is an electrophotographic method. The toner can be suitably used for an electrophotographic toner used in an electrostatic recording method, an electrostatic printing method, or the like.

Claims (5)

  A release agent for toner containing release agent particles, comprising a step of mixing a dispersion of a release agent having a carboxyl group and an acid value of 0.5 to 20 mg KOH / g and a polymer having an oxazoline group. A method for producing an agent dispersion.   The method for producing a release agent dispersion for toner according to claim 1, wherein the mixing step is performed at a temperature of 20 ° C. lower than the melting point of the release agent.   While mixing the release agent dispersion for toner containing the release agent particles obtained by the production method according to claim 1 and the dispersion of resin particles containing a resin having a carboxyl group, the release agent is mixed. An electrophotographic toner production method comprising a step (A) of aggregating mold agent particles and resin particles, and a step (B) of coalescing the aggregated particles obtained in the step (A).   An electrophotographic toner obtained by the production method according to claim 3.   Contains release agent particles obtained by a method having a step of mixing a dispersion of a release agent having a carboxyl group and an acid value of 0.5 to 20 mg KOH / g and a polymer having an oxazoline group. Release agent dispersion for toner.