JP5080341B2 - Method for producing resin particle dispersion - Google Patents

Description

  The present invention relates to a method for producing a resin particle dispersion used in electrophotography, electrostatic recording method, electrostatic printing method, etc., resin particle dispersion obtained by the production method, and electrophotography using the resin particle dispersion. The present invention relates to a toner.

With the development of electrophotographic systems, chemical toners that can be made spherical with a small particle diameter are used in the field of electrophotographic toners from the viewpoint of high image quality. From the viewpoint of particle size control, toners obtained by emulsifying polyesters having different acid values in the presence of an organic solvent are disclosed (for example, Patent Documents 1 and 2).
Furthermore, from the viewpoint of making the particle size distribution uniform, a toner obtained by emulsifying polyesters having different acid values in the presence of an organic solvent is disclosed (Patent Document 3).
Further, due to the recent increase in environmental awareness, a chemical toner that is environmentally friendly, that is, does not use an organic solvent, has been attracting attention, and a chemical toner obtained by emulsifying polyester in an aqueous system has been proposed (Patent Document 4).

JP 2008-33057 A Japanese Patent Laid-Open No. 11-7156 JP 2006-178054 A JP 2007-188004 A

  When the polyester is emulsified with an aqueous medium, it is difficult to emulsify with a polyester having a low acid value. In fact, there was no method other than using a polyester with a high acid value or emulsifying with a solvent system. However, the former method has a large amount of carboxyl groups, so that the charging characteristics under high humidity are not sufficient and the image quality is inferior. On the other hand, the latter method uses an organic solvent, so there is a concern about adverse effects on the environment. .

  The present invention relates to a method for producing a resin particle dispersion capable of obtaining an electrophotographic toner having excellent environmental performance and excellent image stability such as image density and fog, and for electrophotography obtained from the resin particle dispersion. It relates to toner.

The present invention
(1) In a water-based medium, a binder resin containing polyester A having an acid value of 1 to 10 mgKOH / g and polyester B having an acid value of 10 to 40 mgKOH / g is mixed with polyoxyethylene alkyl ether sulfate and nonionic A method for producing a resin particle dispersion having a step of neutralizing with a basic compound in the presence of a surfactant, wherein the binder resin contains 30 to 90% by weight of polyester A, and the acid of polyester B Obtained by agglomerating and coalescing the resin particles in the resin particle dispersion described in (1) above, and (2) a method for producing a resin particle dispersion, which is 9 to 30 mg KOH / g higher than the acid value of polyester A Toner for electrophotography,
About.

  The production method of the present invention is excellent in environmental performance, and by using the resin particle dispersion obtained by the production method of the present invention, an electrophotographic toner excellent in image quality stability under high humidity can be obtained.

[Method for producing resin particle dispersion]
Hereafter, the manufacturing method of the resin particle dispersion liquid of this invention is demonstrated.
(Binder resin)
The binder resin in the present invention contains polyester A having an acid value of 1 to 10 mgKOH / g and polyester B having an acid value of 10 to 40 mgKOH / g, and contains 30 to 90% by weight of the polyester A. In addition, the acid value of polyester B is 9 to 30 mgKOH / g higher than the acid value of polyester A.
Polyester A and polyester B may be either crystalline polyester or amorphous polyester, but both are amorphous polyesters from the viewpoint of the chargeability of the toner and the environmental stability of the charge amount. Preferably there is. As the chargeability of the toner improves, the image quality characteristics of the toner also improve.
In the present invention, the “amorphous polyester” means that the crystallinity index defined by the ratio of the softening point to the endothermic maximum peak temperature (softening point / endothermic maximum peak temperature) is preferably larger than 1.3 and not larger than 4 More preferably, it is 1.5-3. Those having a crystallinity index of 1.3 or less have high crystallinity and are not amorphous polyesters, but are generally called crystalline polyesters. The ratio between the softening point and the maximum peak temperature of endotherm is adjusted by the type and ratio of raw material monomers, molecular weight, production conditions (for example, cooling rate), and the like. The highest endothermic peak temperature can be measured using a differential scanning calorimeter, and refers to the temperature of the highest end of the observed endothermic peaks.

As a raw material monomer for polyester, a known divalent or higher valent alcohol component and a known carboxylic acid component such as a divalent or higher carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester are used.
Specifically, the alcohol component includes ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1, 7-heptanediol, 1,8-octanediol, neopentyl glycol, aliphatic diol such as 1,4-butenediol, aromatic diol such as alkylene oxide adduct of bisphenol A; trivalent or more such as glycerin, pentaerythritol And polyhydric alcohols. These alcohol components may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these, from the viewpoint of toner chargeability, that is, image quality characteristics, polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane, etc. An alkylene (2 to 3 carbon) oxide (average number of added moles 1 to 16) adduct of bisphenol A is preferred.

  As carboxylic acid components, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, etc. Aliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid; Aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; Trimellitic acid; Trivalent or higher polyvalent carboxylic acids such as pyromellitic acid; And anhydrides of these acids, alkyl (carbon number 1 to 3) esters, and the like. Of these, aromatic polyvalent carboxylic acids and acid anhydrides thereof are preferable from the viewpoint of toner chargeability.

Polyester can be produced, for example, by polycondensing the alcohol component and the carboxylic acid component in an inert gas atmosphere at a temperature of 180 to 250 ° C. using a known esterification catalyst as necessary. it can.
The polyester used in the present invention is preferably obtained by mixing polyester A having an acid value of 1 to 10 mgKOH / g and polyester B having 10 to 40 mgKOH / g. When the polyester A having a low acid value is present in the binder resin, the chargeability of the toner becomes good, and therefore the image characteristics become good even in a high humidity environment. Further, in order to stably obtain a binder resin dispersion containing polyester A having a low acid value, polyester B having a high acid value is further contained.
The acid value of the polyester A is preferably 1 to 9 mgKOH / g, more preferably 2 to 8 mgKOH / g, from the viewpoint of good chargeability of the toner, that is, image quality characteristics. Further, the acid value of polyester B is preferably 11 to 35 mgKOH / g from the viewpoint that the effect on the chargeability of polyester A is not hindered and the stability of the resin particle dispersion is good. Preferably it is 12-30 mgKOH / g.

  The difference in acid value between polyester A and polyester B is 9 to 30 mgKOH / g, preferably 12 to 25 mgKOH / g. If the difference is small and less than 9 mgKOH / g, resin particles (emulsified particles) having a small particle size cannot be obtained. If the difference is larger than 30 mgKOH / g, the resin composition and properties of polyester A and polyester B are greatly different, and resin particles cannot be obtained even if a polyester having an appropriate acid value is used. It is not preferable.

In the binder resin, the polyester A is contained in an amount of 30 to 90% by weight, preferably 30 to 80% by weight, and more preferably 50 to 80% by weight. If the content is 30% by weight or more, the chargeability of the toner is good, and if it is 90% by weight or less, fine resin particles can be obtained.
Further, the content ratio of polyester A and polyester B (polyester A / polyester B) is preferably 10/90 to 70/30 by weight, more preferably from the viewpoint of achieving both chargeability, that is, image quality and emulsifying properties. Is 30/70 to 70/30, more preferably 50/50 to 70/30.

  The binder resin may contain a resin other than polyester A and polyester B. Specifically, the following polymers can be mentioned. That is, poly (styrene-butadiene), poly (methyl methacrylate-butadiene), poly (ethyl methacrylate-butadiene), poly (propyl methacrylate-butadiene), poly (butyl methacrylate-butadiene), poly (methyl acrylate) -Butadiene), poly (ethyl acrylate-butadiene), poly (propyl acrylate-butadiene), poly (butyl acrylate-butadiene), poly (styrene-isoprene), poly (methylstyrene-isoprene), poly (methacrylic acid) Methyl-isoprene), poly (ethyl methacrylate-isoprene), poly (propyl methacrylate-isoprene), poly (butyl methacrylate-isoprene), poly (methyl acrylate-isoprene), poly (ethyl acrylate-isoprene), Poly ( Propyl crylate-isoprene), poly (butyl acrylate-isoprene), poly (styrene-butyl acrylate), poly (styrene-butadiene), poly (styrene-isoprene), poly (styrene-butyl methacrylate), poly ( Styrene-butyl acrylate-acrylic acid), poly (styrene-butadiene-acrylic acid), poly (styrene-isoprene-acrylic acid), poly (styrene-butyl methacrylate-acrylic acid), poly (butyl methacrylate-acrylic acid) Butyl), poly (butyl methacrylate-acrylic acid), poly (styrene-butyl acrylate-acrylonitrile-acrylic acid), poly (acrylonitrile-butyl acrylate-acrylic acid) and other vinyl copolymer resins, polyester-styrene-acrylic Hybrid tree Polycondensation resin such as, Besides, polyepoxy, polyurethane, polyethers.

In addition, the acid value of the binder resin containing polyester A and polyester B is 5 to 5 in order to stabilize the resin particles and make the toner having a small particle diameter a sharp particle size distribution and excellent image characteristics. It is preferably 35 mg KOH / g, more preferably 8 to 30 mg KOH / g. In addition, physical properties such as an acid value, a softening point, a glass transition point, and a molecular weight as the binder resin are measured in the same manner as in the individual polyester measurement methods.
Polyester has a softening point of preferably from 80 to 165 ° C, more preferably from 95 to 160 ° C, and a glass transition point of from 50 to 85 ° C, more preferably from 50 to 75 ° C, from the viewpoint of toner storage stability. It is. The desired softening point and acid value can be obtained by adjusting the raw material monomer composition of the reaction conditions such as the condensation polymerization temperature and reaction time.
The number average molecular weight of the polyester is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, and still more preferably 1,000 to 20,000.

  From the same viewpoint as in the case of polyester, the softening point of the binder resin is preferably 80 to 165 ° C, and the glass transition point is preferably 50 to 85 ° C. The number average molecular weight of the binder resin is preferably the same value as that of the polyester. When the binder resin contains a plurality of resins, the average molecular weight, softening point, glass transition point and acid value of the binder resin all mean values as a mixture of the binder resins.

(Surfactant)
The production method of the present invention includes a step of neutralizing the binder resin in the presence of polyoxyethylene alkyl ether sulfate and a nonionic surfactant. That is, in the present invention, when neutralizing the binder resin containing polyester, the polyoxyethylene alkyl ether sulfate and the nonionic surfactant are preferably combined in total with respect to 100 parts by weight of the binder resin. It is preferable that 10 parts by weight or less, more preferably 5 parts by weight or less, and still more preferably 0.1 to 3 parts by weight. Conventionally, in order to emulsify a resin containing a polyester, the polyester could not be emulsified unless the acid value of the polyester was high to some extent. In the present invention, two kinds of polyesters having a specific acid value were added to polyoxyethylene alkyl ether sulfate. By neutralizing in the presence of a salt and a nonionic surfactant, the high acid value polyester is simultaneously neutralized by incorporating the low acid value polyester, and it becomes possible to emulsify the low acid value polyester. Presumed.

In the present invention, polyoxyethylene alkyl ether sulfate is added as an anionic surfactant from the viewpoints of emulsifying properties and resin particle stability. As a polyoxyethylene alkyl ether sulfate, what is represented by following formula (1) is preferable.
R ¹ —O— (CH ₂ CH ₂ O) _p SO ₃ M ¹ (1)
In the formula, R ¹ represents an alkyl group, and preferably an alkyl group having 10 to 20 carbon atoms, more preferably 12 to 18 carbon atoms, from the viewpoint of adsorptivity to aggregated particles and persistence to toner. p represents an average added mole number of 1 to 50, and is preferably 1 to 30, more preferably 2 to 20, from the viewpoint of particle size control. M ¹ represents a monovalent cation, and is preferably sodium, potassium, or ammonium, more preferably sodium, ammonium, or even more preferably sodium from the viewpoint of particle size control. The polyoxyethylene alkyl ether sulfate represented by the formula (1) may have a propylene group as long as the effects of the present invention are not impaired.

In the present invention, a nonionic surfactant is used in combination with the polyoxyethylene alkyl ether sulfate from the viewpoint of producing fine resin particles made of polyester having a low acid value. Examples of the nonionic surfactant include polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkylaryl ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl ethers, polyoxyethylene, and the like. Polyoxyethylene fatty acid esters such as sorbitan monolaurate, polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monostearate, polyethylene glycol monolaurate, polytylene glycol monostearate, polyethylene glycol monooleate, Examples thereof include oxyethylene / oxypropylene block copolymers. Among these, polyoxyethylene alkyl ether is preferably used from the viewpoints of emulsifying properties and resin particle stability.
Although there is no restriction | limiting in particular about the usage-amount of a polyoxyethylene alkyl ether sulfate and a nonionic surfactant, From a viewpoint of emulsifiability and the stability of a resin particle, it is 20: 80-80: 20 by weight ratio. It is preferable that there is, more preferably 30:70 to 70:30.

(Neutralization process)
The production method of the present invention includes a step of neutralizing the binder resin with a basic compound in the presence of the surfactant in an aqueous medium.
The aqueous medium is mainly composed of water, and from the viewpoint of environmental conservation, the water content is preferably 80% by weight or more, more preferably 90% by weight or more, and 100% by weight in the aqueous medium. Further preferred. In the present invention, the binder resin can be dispersed by using only water without substantially using an organic solvent. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, butanol and the like, which are organic solvents that do not dissolve the resin, are preferable from the viewpoint of preventing mixing into the toner.

Basic compound The basic compound may be either an inorganic basic compound or an organic basic compound. Examples of the inorganic basic compound include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, weak acid salts such as carbonates and acetates thereof, partially neutralized salts, and ammonia. . Examples of the organic basic compound include alkylamines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine and triethylamine, alkanolamines such as diethanolamine, and fatty acid salts such as sodium succinate and sodium stearate. These basic compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

The basic compound can be used as a basic aqueous medium, and the content of the basic compound in the basic aqueous medium depends on the type of the basic compound used, but the hydrolysis of the binder resin is difficult. From a viewpoint of suppressing, it is 1-30 weight% normally, Preferably it is 3-20 weight%, More preferably, it is 5-10 weight%. As the aqueous medium used for the basic aqueous medium, the same aqueous medium as that described above can be used.
The amount of the basic aqueous medium used is preferably 5 to 100 parts by weight, more preferably 10 to 90 parts by weight with respect to 100 parts by weight of the binder resin, from the viewpoint that a uniform resin emulsion can be effectively prepared. It is preferably 20 to 80 parts by weight.

Neutralization is preferably carried out by stirring for a certain period of time at a temperature below the softening point of the binder resin, more preferably below the softening point of the binder resin and above the glass transition point of the binder resin. From the viewpoint of uniformly neutralizing the binder resin, the stirring time is preferably 30 minutes or longer, more preferably 1 hour or longer.
By performing the neutralization at a temperature within the above range, the neutralization is sufficiently performed, the generation of large emulsified particles is suppressed by the emulsification treatment in the next step, and no special apparatus is required for heating. In this respect, the neutralization temperature is preferably a temperature of 10 ° C. higher than the glass transition point of the binder resin (hereinafter referred to as “glass transition point + 10 ° C. or higher”), and softening point − The temperature is preferably 5 ° C. or lower.
Furthermore, from the viewpoint of inhibiting hydrolysis, neutralization is more preferably performed near normal pressure. Specifically, 80 to 300 kPa is preferable, and 100 to 200 kPa is more preferable.

  The degree of neutralization in this neutralization step may be such that hydrophilicity necessary for producing resin particles in the next step can be imparted to the resin, and it is not always necessary to neutralize 100%. For example, when a highly hydrophilic resin having many polar groups is used, the degree of neutralization may be low. Conversely, when a resin having low hydrophilicity is used, it is preferable to increase the degree of neutralization. In the present invention, the degree of neutralization is preferably 50% or more, more preferably 60 to 100%, and still more preferably 70 to 100%. The degree of neutralization can generally be represented by the ratio of the number of moles of acid groups before and after neutralization (number of moles of acid groups after neutralization / number of moles of acid groups before neutralization).

  Specifically, the resin dispersion is stirred at a temperature equal to or lower than the softening point of the resin, preferably above the glass transition point, for example, a carboxyl having a glass transition point of about 60 to 65 ° C. and a softening point of about 110 to 120 ° C. When the polyester having a group is used, neutralization can be performed by raising the temperature to about 90 to 100 ° C. and holding at that temperature for an appropriate time until reaching a predetermined degree of neutralization.

(Production of resin particle dispersion)
The production method of the present invention includes the above neutralization step and preferably emulsifies a binder resin containing polyester in the aqueous medium to obtain resin particles.
In the production of the resin particle dispersion, additives such as a coloring agent, a release agent, a charge control agent, a reinforcing filler such as a fibrous substance, an antioxidant, and an anti-aging agent are added to the binder resin as necessary. And the mixture is dispersed. Moreover, well-known surfactants other than the said surfactant can also be used in the range which does not inhibit the effect of this invention.

The colorant is not particularly limited, and any known colorant can be used and can be appropriately selected. 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 0.01 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide and stearic acid amide; carnauba wax, rice wax, Plant waxes such as candelilla wax; animal waxes such as beeswax; mineral / petroleum waxes such as montan wax, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax.
The content of the release agent is usually about 1 to 20 parts by weight, preferably 2 to 100 parts by weight with respect to the total amount of the binder resin and the colorant in consideration of the addition effect and the adverse effect on the chargeability. 15 parts by weight.

Examples of charge control agents include benzoic acid metal salts, salicylic acid metal salts, alkyl salicylic acid metal salts, catechol metal salts, metal-containing bisazo dyes, tetraphenylborate derivatives, quaternary ammonium salts, alkylpyridinium salts, and the like. Can be mentioned. These may be used individually by 1 type and may be used in combination of 2 or more type.
The content of the charge control agent is usually 10 parts by weight or less, preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the total amount of the binder resin and the colorant.

In the present invention, after the neutralization step, it is preferable to produce a resin particle dispersion by emulsification by adding an aqueous medium at a temperature equal to or higher than 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 from 100 to 2,000 parts by weight, more preferably from 150 to 1,500 parts by weight, based on 100 parts by weight of the binder resin, from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation treatment. From the viewpoint of stability and handleability of the obtained emulsified particle liquid, the solid content concentration of the resin emulsion 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 The solid content includes nonvolatile components such as a binder resin and a surfactant.

  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 binder 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 a glass transition point of the binder resin + 10 ° C. or more, and preferably a softening point of −5 ° C. or less.

As another method for obtaining a resin emulsion by emulsifying a binder resin in an aqueous medium, for example, first, a polycondensable monomer as a target resin particle raw material in an aqueous medium, for example, mechanical share or A method of emulsifying and dispersing by ultrasonic waves or the like can be mentioned. 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 binder 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, the polycondensation resin is dehydrated during polymerization, so that the reaction does not proceed in an aqueous medium in principle. 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 in an aqueous medium is obtained with low energy.

[Resin particle dispersion]
The present invention also relates to a resin particle dispersion obtained by the above method for producing a resin particle dispersion, and the production method is as described above.
The solid content concentration of the resin particle dispersion obtained by the production method of the present invention is 7 to 50% by weight from the viewpoint of the stability of the emulsion and the handleability of the resin particle dispersion in the subsequent aggregation step. Is preferable, 7 to 45 weight% is more preferable, and 10 to 40 weight% is further more preferable.

Further, the volume median particle size (D50) of the resin particles in the resin particle dispersion after forming the O / W type emulsion is used for uniform aggregation in the aggregation process when the toner is produced. Preferably it is 0.02-2 micrometer, More preferably, it is 0.05-1 micrometer, More preferably, it is 0.05-0.6 micrometer. From the same viewpoint, the particle size distribution is preferably 60 or less, more preferably 45 or less in terms of CV value (standard deviation of particle size distribution / volume median particle size (D50) × 100). In the present specification, the 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.
The weight average molecular weight of the resin in the resin particles is preferably 5,000 to 150,000 from the viewpoint of hydrolysis resistance of the resin, durability of the toner and fixability, and is 10,000 to 120,000. More preferably.

The electrophotographic toner using the resin particle dispersion of the present invention will be described below.
[Electrophotographic toner]
An electrophotographic toner can be obtained by agglomerating the resin particles in the resin particle dispersion obtained as described above (hereinafter referred to as an aggregating step) and further integrating (hereinafter referred to as an integrating step). .

Aggregating step In the aggregating step, an aggregating agent is added for effective aggregation. 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, and aluminum sulfate, and polyaluminum chloride and polyaluminum hydroxide. An inorganic metal salt polymer is mentioned. 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.

  Examples of water-soluble nitrogen-containing compounds having a molecular weight of 350 or less 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 productivity, ammonium sulfate (pH value of 10% by weight 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, 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, that is, image quality stability. Is more preferable, and 30 parts by weight or less is more preferable. From the viewpoint of cohesiveness, the amount is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and still more preferably 5 parts by weight or more with respect to 100 parts by weight of the binder resin. 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 further 5 to 30 parts by weight with respect to 100 parts by weight of the binder resin. preferable.

  The addition of the flocculant is performed after adjusting the pH in the system, and then the glass transition point of the binder resin + 20 ° C. or lower, preferably the glass transition point + 10 ° C. or lower, more preferably the glass transition point + 5 ° C. or lower. To do. 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 a softening point of the binder resin of −100 ° C. or higher, more preferably at a softening point of −90 ° C. or higher. 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.

From the same viewpoint, the temperature in the system in the aggregation process is preferably a softening point of the binder resin of −50 ° C. or higher and a softening point of −10 ° C. or lower, more preferably a softening point of −30 ° C. or higher and a softening point of −10 ° C. or lower. .
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, the aggregated particles are prepared by aggregating the resin particles in the resin particle dispersion.
The aggregated particles preferably have a volume median particle size (D50) in the range of 1 to 10 μm, more preferably 2 to 9 μm, and even more preferably 2 to 5 μm, from the viewpoint of reducing the particle size. The variation coefficient (CV value) of the particle size distribution is preferably 30 or less, more preferably 28 or less, and still more preferably 25 or less.

In the present invention, it is preferable to add a surfactant after aggregating the resin particles, and at least one selected from the group consisting of alkyl ether sulfates, alkyl sulfates, and linear alkylbenzene sulfonates is added. More preferably.
As the alkyl ether sulfate, those similar to those represented by the formula (1) are preferably used.

The linear alkyl benzene sulfonate is not particularly limited, but is preferably a compound represented by the formula (2) from the viewpoint of adsorptivity to aggregated particles and persistence to toner.
R ² -Ph-SO ₃ M ² (2)
In the formula, R ² represents a linear alkyl group, and is the same as the linear ^one of R ^{1 in} the formula (1). Ph is a phenyl group, and M ² is a monovalent cation. As the linear alkylbenzene sulfonate, sodium sulfate is preferably used.
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.

In the present invention, the resin contained in the resin particle dispersion of the present invention at the time of agglomeration from the viewpoint of preventing the release of a release agent or the like or setting the charge amount between colors to the same level in a color toner. Other fine resin particles can be added to the particles (hereinafter sometimes referred to as “resin particles of the present invention”) at one time or divided into a plurality of times. Conversely, the resin particles of the present invention can be added to other resin fine particles at once or divided into a plurality of times for aggregation.
There is no restriction | limiting in particular as another resin fine particle added to the resin particle of this invention, For example, what was prepared similarly to the resin particle of this invention can be used.

In the present invention, the other resin fine particles may be the same as or different from the resin particles of the present invention. From the viewpoint of low-temperature fixability and storability of the toner, the present invention is preferable. The resin particles different from the resin particles are added at a later time or divided into a plurality of times.
In this step, the other resin fine particles may be mixed with the aggregated particles obtained by adding the flocculant as described above to the resin particle dispersion of the present invention.
In the present invention, the addition timing of the other resin fine particles is not particularly limited. However, from the viewpoint of productivity, it is preferable that the addition of the flocculant is performed until the later-described coalescence step.

In this step, the resin particles of the present invention may be mixed with aggregated particles obtained by adding an aggregating agent to the other resin fine particles.
The blending ratio of the resin particles of the present invention to other resin fine particles (the resin particles of the present invention / other resin fine particles) is 0.1 to 2 by weight from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner. It is preferably 0.0, more preferably 0.2 to 1.5, and still more preferably 0.3 to 1.0.
The obtained agglomerated particles are subjected to a step of combining them (unification step).

The coalescence process The coalescence process is a process of coalescing the aggregated particles obtained in the aggregation process.
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 binder resin is preferable, the softening point + 20 ° C. or lower is more preferable, the glass transition point + 5 ° C. or higher, the softening point + 15 ° C. or lower is more preferable, and the softening point + 10 ° C. or higher. More preferably, it is not higher than ° C. 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 2 to 10 μm, more preferably 2 to 8 μm, and more preferably 2 to 7 μm. More preferably, it is ˜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 from the resin particle dispersion obtained by the method for producing the resin particle dispersion of the present invention. Particles).
Further, from the viewpoint of high image quality and productivity, the volume median particle size (D50) of the toner particles is preferably 1 to 10 μm, more preferably 2 to 8 μm, and further preferably 3 to 7 μm. From the same viewpoint, the particle size distribution has a CV value of preferably 25 or less, more preferably 20 or less, and still more preferably 18 or less.

  Further, the softening point of the toner is preferably 60 to 140 ° C., more preferably 60 to 130 ° C., and further preferably 60 to 120 ° C. from the viewpoint of low-temperature fixability. Moreover, 30-80 degreeC is preferable from a durable viewpoint, and, as for a glass transition point, 40-70 degreeC is more preferable.

In the toner of the present invention, toner particles can be used as toner, or toner particles obtained by adding an additive such as a fluidizing agent to the toner particles as an external additive. 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 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 particles before the treatment with the external additive. However, when hydrophobic silica is used as an external additive, it is preferable to use 1 to 3 parts by weight of hydrophobic silica with respect to 100 parts by weight of toner particles before treatment 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.

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 changed from a mixed solvent of ethanol and ether to a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).
[Softening point and glass transition point of resin and toner]
(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 temperature The sample was heated to 200 ° C. using a differential scanning calorimeter (“Pyris 6 DSC” manufactured by Parkin Elmer), and the sample cooled from the temperature to 0 ° C. at a temperature lowering rate of 10 ° C./min was heated up. Measure at 10 ° C./min.If a peak is observed at a temperature 20 ° C. or more lower than the softening point, the peak temperature is observed, and a step is observed without a peak being observed at a temperature 20 ° C. or higher lower than the softening point. When this is done, the temperature at the intersection of the tangent line showing the maximum slope of the curve of the step and the extension line of the base line on the high temperature side of the step is read as the glass transition point.

[Particle size and particle size distribution of emulsified particles]
(1) Measuring device: Laser diffraction 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 (D ₅₀ ) is measured at a temperature at which the absorbance is in an appropriate range. The CV value was calculated according to the following formula.
CV value = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

[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).

[Solid concentration of resin dispersion]
Using an infrared moisture meter (Ketto Science Laboratory Co., Ltd .: FD-230), 5 g of the emulsion was wet at a drying temperature of 150 ° C. and in a measurement mode 96 (monitoring time 2.5 minutes / variation width 0.05%). Measure the moisture content of the base. The solid content concentration was calculated according to the following formula.
Solid content concentration (%) = 100-M
M: wet base moisture (%) = [(W−W0) / W] × 100
W: Sample weight before measurement (initial sample weight)
W0: Sample weight after measurement (absolute dry weight)

Production Example 1 (Production of polyester a)
17,150 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 29,575 g of polyoxyethylene (2.0) -2, 2-bis (4-hydroxyphenyl) propane, 21,381 g of terephthalic acid and 15 g of dibutyltin oxide were placed in a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, stirred at 230 ° C. in a nitrogen atmosphere, and measured according to ASTM D36-86 Reaction was performed until the softening point reached 110 ° C. to obtain polyester a. Polyester a had a softening point of 111 ° C., a glass transition point of 68 ° C., and an acid value of 5.0 mgKOH / g. 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 2 (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 placed in a four-necked flask equipped with a nitrogen introducing tube, a dehydrating tube, a stirrer and a thermocouple, The mixture was stirred at 220 ° C. in a nitrogen atmosphere 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, and an acid value of 21 mgKOH / g. 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 3 (Production of polyester c)
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 c. Polyester c had a softening point of 110 ° C., a glass transition point of 66 ° C., and an acid value of 24 mgKOH / g. When 1 kg of the obtained polyester c was sieved with a sieve having an opening diameter of 5.6 mm, nothing remained on the sieve.

Production Example 4 (Production of polyester d)
34,090 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 5,800 g of fumaric acid and 15 g of dibutyltin oxide (esterification catalyst) were added under normal pressure (101. The mixture was stirred at 230 ° C. under 3 kPa) and reacted until the softening point measured according to ASTM D36-86 reached 100 ° C. to obtain polyester d. Polyester d had a softening point of 98 ° C., a glass transition point of 56 ° C., and an acid value of 22 mgKOH / g. When 1 kg of the obtained polyester d was sieved with a sieve having an opening diameter of 5.6 mm, nothing remained on the sieve.

Example 1
In a 2-liter stainless steel kettle, 390.0 g of polyester a, 210.0 g of polyester b, copper phthalocyanine pigment (ECB-301: manufactured by Dainichi Seika Kogyo Co., Ltd.) ) "Polyoxyethylene (2 mol) sodium lauryl ether sulfate (solid content: 27% by weight) 22.2 g, nonionic surfactant" Emulgen 430 (manufactured by Kao Corporation) "polyoxyethylene (26 mol) oleyl ether (HLB: 16.2) 6.0 g and 52.8% by weight potassium hydroxide aqueous solution 292.8 g were dispersed at 95 ° C. with stirring at 200 r / min with a Kai-type stirrer. The mixture was held for 2 hours under stirring at 200 r / min with a Kai-type stirrer. Subsequently, deionized water was added dropwise at 6 g / min while stirring at 200 r / min with a Kai-type stirrer. The system temperature was maintained at 95 ° C. After cooling, the resin emulsion 1 was atomized through a 200 mesh (mesh: 105 μm) wire mesh. The resin particles in the obtained resin emulsion 1 had a volume median particle size of 0.260 μm, a CV value of 25, a solid content concentration of 31% by weight, and no resin component remained on the wire mesh.

Example 2
Resin emulsion 2 was prepared in the same manner as in Example 1, except that polyester b was replaced with polyester c. The resin particles in the obtained resin emulsion 2 had a volume-median particle size of 0.220 μm, a CV value of 26, a solid content concentration of 31% by weight, and no resin component remained on the wire mesh.

Example 3
In Example 1, the polyester b was replaced with the polyester d, and 300 g of the polyester a and 300 g of the polyester b were used. The anionic surfactant “Emar E27C (manufactured by Kao)” polyoxyethylene (2 mol) sodium lauryl ether sulfate was used. Instead, “Emal 20C (manufactured by Kao Corporation)” Polyoxyethylene (3 mol) Resin emulsion 3 was prepared in the same manner except that it was replaced with sodium lauryl ether sulfate. The resin particles in the obtained resin emulsion 3 had a volume median particle size of 0.351 μm, a CV value of 31 and a solid content concentration of 30% by weight, and no resin component remained on the wire mesh.

Comparative Example 1
In Example 1, an attempt was made to prepare a resin emulsion in the same manner except that the mixing of polyester a and polyester b was changed to 600.0 g of polyester a alone, but emulsification could not be performed.

Comparative Example 2
In Example 1, an anionic surfactant “Emar E27C (manufactured by Kao Co., Ltd.)” Polyoxyethylene (2 mol) Sodium lauryl ether sulfate was used instead of sodium dodecylbenzenesulfonate, and the resin emulsion was similarly treated. An attempt was made to prepare, but emulsification failed.

Comparative Example 3
Resin emulsion 4 was prepared in the same manner as in Example 1 except that the mixing of polyester a and polyester b was changed to 600.0 g of polyester c alone. The volume median particle size of the resin particles in the obtained resin emulsion 4 was 0.186 μm, the CV value was 28, and the solid content concentration was 31% by weight.
Details of Examples 1 to 3 and Comparative Examples 1 to 3 are summarized in Table 1.

Example 4
400 g of resin emulsion 1 was mixed in a 2 liter container at room temperature. Next, under stirring at 100 r / min with a Kai-type stirrer, 6.30 g of ammonium sulfate (molecular weight: 132.14) as a flocculant was dissolved in 104 g of deionized water, and an aqueous solution (pH: 6.1, 0.25 mmol / L) was added dropwise at room temperature over 15 minutes. Thereafter, the mixed dispersion was heated at 1 ° C./5 min to form aggregated particles. When the temperature reached 85 ° C., the mixture was fixed at 85 ° C. and stirred for 1.5 hours, and then heating was stopped.
After cooling to room temperature, colored resin particle powder (toner particles) was obtained through a suction filtration step, a washing step and a drying step. The volume median particle size (D50) of the toner particles was 4.9 μm.
To 100 parts by weight of the toner particles, 1.0 part by weight of hydrophobic silica (manufactured by Wacker Chemie, “TS530”, primary number average particle diameter: 8 nm) was externally added using a Henschel mixer, and cyan toner A It was. With the obtained toner A, a good image was obtained with a commercially available full color printer. The obtained toner A had a softening point of 107 ° C. and a glass transition point of 61 ° C.

Examples 5 and 6 and Comparative Example 4
Except that the resin emulsion 1 was changed as shown in Table 2, Examples 5 and 6 and Comparative Example 4 were carried out in the same manner as Example 4, and cyan toner B (Example 5), cyan toner C (Example) 6) and cyan toner D (Comparative Example 4) were obtained.
The obtained toner B has a volume median particle size (D50) of 4.8 μm, a softening point of 106 ° C. and a glass transition point of 60 ° C., and toner C has a volume median particle size (D50) of 4.9 μm. The softening point was 107 ° C., the glass transition point was 62 ° C., the volume median particle size (D50) of toner D was 5.1 μm, the softening point was 104 ° C., and the glass transition point was 60 ° C.

  Each toner obtained above was stored for 12 hours under the conditions of 20 ° C., 50% RH (normal environment) and 20 ° C., 85% RH (high humidity environment), and then subjected to an image density test and fog as follows. A test was conducted to evaluate the image quality stability. The results are shown in Table 2.

[Print image density test]
Using a commercially available printer (OKI, “ML5400”) on high-quality paper (Fuji Xerox Co., Ltd., J paper A4 size), place the image on 30 sheets of J paper and place the colorimeter (Gretag-Macbeth, “SpectroEye”) was used to measure the reflection image density when the light emission conditions were a standard light source D ₅₀ , an observation field of view 2 °, a density reference DIN NB, and an absolute white reference.

[Toner fog test]
A solid image is printed on the J paper using the printer, and when the image is transferred to half of A4, the machine is stopped, and a transparent mending tape (manufactured by 3M: SCOTCH mending tape 810) is applied to the surface of the photoconductor before transfer. -3-18) is affixed, and fog toner on the surface of the photoreceptor is collected.
A reference mending tape and a mending tape from which fog toner is collected are affixed to unused J paper, placed on 30 sheets of J paper, and a colorimeter ("SpectroEye", manufactured by Gretag-Macbeth). The CIE L * a * b * is measured using the standard white light source D ₅₀ and the whiteness of the reference mending tape as a white reference when the light emission condition is a standard light source D ₅₀ . Thereafter, CIE L * a * b * of the mending tape from which the fog toner was collected is measured, and a color difference ΔE = (ΔL * ² + Δa * ² + Δb * ² ) ^1/2 with respect to the reference is obtained. Is the photoreceptor fog. ΔE indicates that the smaller the value, the less the fog and the better.

  A toner using the method for producing a resin particle dispersion of the present invention is excellent in charging stability under high humidity, that is, image quality stability, and therefore can be suitably used as an electrophotographic toner.

Claims (5)

  In an aqueous medium, a binder resin containing polyester A having an acid value of 1 to 10 mgKOH / g and polyester B having an acid value of 10 to 40 mgKOH / g is treated with polyoxyethylene alkyl ether sulfate and nonionic surface activity. A method for producing a resin particle dispersion having a step of neutralizing with a basic compound in the presence of an agent, wherein the binder resin contains 30 to 90% by weight of polyester A, and the acid value of polyester B is polyester. A method for producing a resin particle dispersion, which is 9 to 30 mg KOH / g higher than the acid value of A.   The method for producing a resin particle dispersion according to claim 1, wherein the binder resin containing polyester A and polyester B has an acid value of 5 to 35 mg KOH / g.   The method for producing a resin particle dispersion according to claim 1 or 2, wherein both polyester A and polyester B are amorphous polyesters.   The resin particle dispersion according to any one of claims 1 to 3, wherein the polyoxyethylene alkyl ether sulfate has an alkyl group having 10 to 20 carbon atoms and an average addition mole number of ethylene oxide of 1 to 50. Production method.   An electrophotographic toner obtained by agglomerating and coalescing the resin particles in the resin particle dispersion according to claim 1.