JP2008070466A - Masterbatch for toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance productivity in emulsification and the image density of toner because even when a masterbatch of a colorant is used in toner manufacture, emulsifiability in emulsification can be improved and occurrence of coarse particles can be suppressed. <P>SOLUTION: A masterbatch for toner containing a resin, a colorant and a plasticizer is provided. A method for preparing a resin emulsified liquid for toner is provided comprising a step of mixing at least the masterbatch and a binder resin, and a step of dispersing and emulsifying the resulting mixture in an aqueous medium, wherein the ratio between the melt viscosity of the masterbatch and the melt viscosity of the binder resin at 95°C measured with a flow tester (the viscosity of the masterbatch/the viscosity of the binder resin) is 0.1-0.5. There are also provided a resin emulsified liquid for toner obtained by the method for preparing a resin emulsified liquid for toner, an electrophotographic toner obtained using the resin emulsified liquid and a method for manufacturing the same. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic toner used in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and a resin emulsion and a master batch used in the toner.

In the field of electrophotographic toner, with 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 chemical methods such as a polymerization method and an emulsifying dispersion method have been proposed instead of the conventional melt-kneading method. In such a method, in order to improve the dispersibility of the colorant, a masterbatch of the colorant has been used together with the toner binder resin. For example, Patent Document 1 proposes a technique for preparing emulsified particles having excellent dispersibility of a colorant by using a mixture of a colorant master batch and a binder resin during emulsification.
However, in the above technique, depending on the type of the colorant, emulsification may be difficult due to the interaction with the resin forming the master batch.

JP 2006-171691 A

  The present invention relates to a master batch capable of reducing the viscosity by reducing the interaction between the colorant and the resin forming the master batch, and the present invention relates to the master batch of the colorant in the production of the toner. Even when used, the emulsifiability at the time of emulsification can be greatly improved, and the generation of coarse particles can be reduced, so that the master batch for toner that can remarkably improve the productivity at the time of emulsification and the image density of the toner, The present invention relates to a resin emulsion obtained by using the master batch, an electrophotographic toner using the resin emulsion, and a production method thereof.

The present invention
(1) a toner masterbatch comprising a resin, a colorant and a plasticizer;
(2) A resin emulsion for toner obtained by dispersing and emulsifying the master batch and the binder resin described in (1) above in an aqueous medium,
(3) A method for producing a resin emulsion, comprising at least a step of mixing the master batch and the binder resin described in (1) above, and a step of dispersing and emulsifying the obtained mixture in an aqueous medium, Resin emulsification for toner in which the ratio of the melt viscosity of the master batch and the melt viscosity of the binder resin at 95 ° C. (the viscosity of the master batch / the viscosity of the binder resin) at 95 ° C. is 0.1 to 0.5. Production method of liquid,
(4) A method for producing a toner for electrophotography, comprising: a step of obtaining a resin emulsion by the production method described in (3) above; and a step of aggregating and coalescing the emulsion particles in the obtained resin emulsion; 5) An electrophotographic toner obtained by the production method described in (4) above,
I will provide a.

  According to the present invention, it is possible to provide a master batch that can reduce the viscosity by reducing the interaction between the colorant and the resin forming the master batch. Further, according to the present invention, even when a master batch of a colorant is used, the emulsifiability at the time of emulsification can be greatly improved, and the generation of coarse particles can be reduced. It is possible to provide a toner masterbatch that can be remarkably improved, a resin emulsion obtained using the masterbatch, an electrophotographic toner using the same, and a production method thereof.

[Master batch for toner]
The toner master batch of the present invention will be described.
The toner masterbatch of the present invention contains a resin, a colorant and a plasticizer, and is prepared for toner. The toner masterbatch of the present invention is preferably one in which a colorant is dispersed in a resin, more preferably at least a resin, a colorant, and a plasticizer, from the viewpoint of achieving the above-described problems of the present invention. It is obtained by melt kneading.
The resin used in the toner masterbatch of the present invention may be the same type of resin as the binder resin used in the production of the toner described later or a different type of resin, but from the viewpoint of dispersibility of the colorant, The same type of resin is preferred. For example, when the binder resin contains polyester, the masterbatch resin preferably contains polyester having the same or different composition as the binder resin. In this invention, the said resin can be used individually by 1 type or in combination of 2 or more types.

  In addition, the acid value of the resin used in the master batch is lower than the acid value of the binder resin mixed with the master batch from the viewpoint of dispersibility of the colorant in the binder resin mixed with the master batch. More preferably, the value is 1 mg KOH / g or more lower than the acid value of the binder resin, and more preferably 1.5 mg KOH / g or less. When the resin and / or the binder resin contain a plurality of resins, the acid value of the resin and the binder resin means a value as a mixture of the resins.

The colorant contained in the masterbatch is not particularly limited and is known black,
Any colorant such as yellow, magenta, and cyan can be used. Specifically, carbon black, inorganic composite oxide, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, Brilliantamine 6B, DuPont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Bengal, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, Acridine, Xanthene, Azo Benzoquinone, azine, anthraquinone, indico, thioindico, phthalocyanine, aniline black, thiazole One of the various dyes and the like, alone or in combination of two or more can be used. In the present invention, a magenta pigment is preferably used, more preferably a quinacridone pigment, and still more preferably a dimethylquinacridone pigment, from the viewpoint of significantly achieving the object of the present invention.
The content of the colorant in the masterbatch is preferably 10 to 50% by weight, more preferably 20 to 40% by weight, more preferably 25 to 35% by weight, from the viewpoint of dispersibility of the colorant and productivity. Further preferred. The colorant is preferably contained in an amount of 14 to 70 parts by weight, more preferably 28 to 57 parts by weight, and still more preferably 35 to 50 parts by weight with respect to 100 parts by weight of the resin in the master batch.

  The type of plasticizer is not particularly limited, and any known plasticizer used for polymer materials can be used. Examples of plasticizers include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones that have a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide; Plant waxes such as uba wax, rice wax, candelilla wax, wood wax, jojoba oil; animal waxes such as beeswax; minerals and petroleum such as montan wax, ozokerite, ceresin wax, microcrystalline wax, Fischer-Tropsch wax In addition to waxes such as system waxes, surfactants and the like can also be used. Among the activators, nonionic surfactants are preferable from the viewpoint of viscosity control. Specifically, polyoxyethylene alkylallyl such as polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, etc. Ether or polyoxyethylene alkyl ethers, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monostearate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol Examples thereof include polyoxyethylene fatty acid esters such as monooleate, and oxyethylene / oxypropylene block copolymers.

Among these, in the present invention, polyoxyethylene (average added mole number: 10 to 60 mole) alkyl (carbon number 8 to 18) ether is preferably used from the viewpoint of dispersibility and emulsifying property. Specifically, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, and polyoxyethylene lauryl ether can be preferably used.
In the present invention, the plasticizers can be used alone or in combination of two or more. The content of the plasticizer in the masterbatch is preferably 0.2 to 2% by weight, more preferably 0.5 to 2% by weight, from the viewpoint of both the effect of reducing the melt viscosity and the emulsifying property. More preferred is 0.0 to 1.5% by weight. The plasticizer is preferably 0.2 to 2 parts by weight, more preferably 0.5 to 2 parts by weight, with respect to 100 parts by weight of the resin and pigment in the master batch. More preferred is 1.5 parts by weight.

As a manufacturing method of the masterbatch of the present invention, for example,
Method (1): A dry powdery colorant, a resin, a plasticizer, and, if necessary, a dispersion aid such as water are charged in a mixer or kneader and mixed to wet the colorant and resin. A method in which the colorant, the resin and the plasticizer are melt-kneaded by heating under reduced pressure or normal pressure, and then the water is evaporated and dried under normal pressure or reduced pressure.
Method (2): After the dried colorant and resin are heated to melt the resin, water and a plasticizer are added, and the colorant, resin and plasticizer are melt-kneaded under pressure or normal pressure to remove moisture. A method of evaporating under normal pressure or reduced pressure to remove by drying,
Method (3): A method of removing moisture by melting and kneading a colorant press cake (including an aqueous paste) and a resin together with a plasticizer to transfer the aqueous phase colorant to the resin phase,
Etc.
Here, the press cake of the colorant refers to a product obtained by dehydrating an aqueous dispersion of the colorant by appropriate filtration. The solid content (colorant) amount in the press cake of the colorant is preferably 20 to 60% by weight, and from the viewpoint of dispersibility of the colorant in the resin, the press cake is 20 to 50% by weight in the form of an aqueous paste. Is more preferable.

  Among these methods, the method (3) is preferable from the viewpoint of dispersibility of the colorant, and the master batch obtained by the method (3) is generally called a flushing master batch. In the production of the flushing masterbatch, the colorant in the aqueous phase shifts to the resin phase by kneading the colorant press cake and the resin. Then, the resin is softened in a bowl shape by the strong shearing action of the kneader during flushing, and the colorant is transferred and dispersed in the resin by the action of the internal shearing force of the resin softened in the bowl shape. Therefore, the flushing master batch has better dispersibility of the colorant compared to the method using the colorant once dried as in the method (1) or the method (2). In addition, when producing a masterbatch by the method (3) using only the colorant and the resin, depending on the type of the colorant, in the emulsification step in the toner production due to the interaction with the resin forming the masterbatch, Sometimes emulsification was difficult to perform. In the present invention, by using the plasticizer together with the colorant and the resin, the interaction between the colorant and the resin forming the master batch can be reduced, and the emulsification in the emulsification step during toner production is greatly improved. Can be improved. As a result, the generation of coarse particles can be reduced, and the productivity during emulsification, the concentration of the emulsion, and the image density of the resulting toner can be significantly improved.

  In general, a synthetic colorant is a micron order crystal and is called a colorant crude. The colorant press cake used in the production of the flushing masterbatch may be a colorant crude presscake, but it is a fine colorant presscake obtained by refining the colorant crude by a physical method or chemical treatment. Preferably there is.

  One physical method for miniaturizing the colorant crude is a mechanical grinding method. Although the method by mechanical grinding is not particularly limited, for example, a grinding medium such as a metal ball, a ceramic ball or other milling ball is put into the crusher, and the grinding action is manifested by the vibration of the crusher. Or a method of causing the grinding action by vibration and rotation by further rotating the crusher itself like a drum. At the time of grinding, the grinding effect can be enhanced by using grinding aids such as salt and salt cake as grinding aids. Therefore, the colorant used as a raw material of the flushing masterbatch in the present invention is ground by a method called salt milling using a salt such as salt as a grinding aid from the viewpoint of reducing the particle size of the colorant. A colorant presscake is preferred. The dried colorant crude is usually dried under reduced pressure by heating with a heating source (circulation of a heating medium such as water vapor) installed in a dryer. Drying can be performed batchwise, continuously, or the like. Examples of the dryer that can be used in the above method include commercially available products called vibration fluidized dryers, vibration mills equipped with heating devices and decompression devices, and the like. By the method of grinding in a dryer and drying, the reaction mixture containing the colorant and reaction solvent obtained through the synthesis step is directly ground and dried without going through the pigmentation step, thereby reducing the colorant. Can also be manufactured.

The resin used for the flushing masterbatch is preferably a resin having a softening point of preferably 130 ° C. or lower, and the temperature at which the colorant press cake and the resin are kneaded is a temperature lower than the melting point of the resin or the softening point. Thus, the temperature is preferably lower than the boiling point of water, and the pressure is preferably normal pressure.
Further, in the production of the flushing masterbatch, when kneading the colorant press cake and the resin, an organic solvent can be used as necessary. However, the flushing masterbatch used in the present invention is an organic solvent. It is preferable that is not substantially used.
In the present invention, the toner master batch has a melt viscosity at 95 ° C. of preferably 10,000 to 100,000, more preferably 10, from the viewpoint of compatibility between the colorant dispersibility and the emulsifying property. 000-80,000. The viscosity can be measured using a flow tester (Shimadzu Corporation, “CFT-500D”), specifically by the method described later.
The toner master batch of the present invention can reduce the interaction between the colorant and the resin forming the master batch by using a plasticizer. As a result, when producing toner using this master batch, the emulsification during emulsification can be greatly improved and the generation of coarse particles can be reduced, significantly improving the productivity during emulsification and the toner image density. can do.

[Resin emulsion for toner and method for producing the same]
Next, the resin emulsion for toner of the present invention will be described.
The resin emulsion for toner of the present invention is obtained by mixing the toner master batch of the present invention and a binder resin, and dispersing and emulsifying the obtained mixture in an aqueous medium. The ratio of the melt viscosity of the batch to the melt viscosity of the binder resin (the viscosity of the master batch / the viscosity of the binder resin) is 0.1 to 0.5.

Binder Resin The binder resin used in the present invention preferably contains polyester from the viewpoints of toner fixability and durability. 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 from the viewpoint of fixing property and durability in the binder resin. Is more preferable.
Examples of binder resins other than polyester include known resins used in toners, such as styrene-acrylic resins, epoxy resins, polycarbonates, and polyurethanes.

The raw material monomer of the polyester is not particularly limited, and a known alcohol component and a known carboxylic acid component such as carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester are used.
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 of 2 to 3). ) Oxide (average addition mole number 1-16) adduct, ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or their alkylene (2-4 carbon atoms) oxide (average) Addition mole number 1-16) Additions etc. are mentioned.
This alcohol component may be used individually by 1 type, and may be used in combination of 2 or more type.

The carboxylic acid component includes dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, adipic acid and succinic acid, alkyl groups having 1 to 20 carbon atoms such as dodecenyl succinic acid and octenyl succinic acid, or carbon. Trivalent or higher polyvalent carboxylic acids such as succinic acid, trimellitic acid and pyromellitic acid substituted with alkenyl groups of 2 to 20, anhydrides of these acids and alkyls of these acids (1 to 3 carbon atoms) ) Esters and the like.
This carboxylic acid component may be used individually by 1 type, and may be used in combination of 2 or more type.

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.

From the viewpoint of 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 acid value is preferably 6 to 35 mgKOH / g, more preferably 10 to 35 mgKOH / g, and still more preferably 15 to 35 mgKOH / g, from the viewpoint of manufacturability during emulsification. Further, as described above, the acid value of the binder resin is preferably a value equal to or higher than the acid value of the resin used for the masterbatch, and more preferably 1 mgKOH / g or more higher than the acid value of the resin used for the masterbatch. Value, more preferably 1.5 mgKOH / g or higher. The desired softening point and acid value can be obtained by adjusting the condensation polymerization temperature and reaction time.
From the viewpoint of the durability of the toner, the number average molecular weight of the polyester is preferably 1,000 to 10,000, and more preferably 2,000 to 8,000.
Further, from the viewpoint of productivity and toner durability, the melt viscosity of the binder resin at 95 ° C. is preferably 50,000 to 500,000, more preferably 100,000 to 500,0000.

When the binder resin contains a plurality of binder resins, the softening point, glass transition point, acid value, number average molecular weight and melt viscosity of the binder resin are all as a mixture of the binder resins. Means the value of
Further, the binder resin for toner of the present invention can contain two kinds of polyesters having different softening points from the viewpoint of fixability and durability, and the softening point of one polyester (a) is 70 to 115 ° C. The softening point of the other polyester (b) is preferably 115 ° C. or higher and 165 ° C. or lower.
The melt viscosity of the polyester (a) is preferably 10,000 or more and less than 100,000, more preferably 15,000 or more and 80,000 or less, and further preferably 20,000 or more and 50,000 or less. . The melt viscosity of the polyester (b) is preferably 100,000 or more and 1,000,000 or less, more preferably 200,000 or more and 800,000 or less, and further preferably 300,000 or more and 6,000,000 or less. .
The weight ratio (a / b) between the polyester (a) and the polyester (b) is preferably 10/90 to 90/10, and more preferably 50/50 to 90/10.

Aqueous medium The aqueous medium is mainly composed of water. In view of environmental properties, the content of water in the aqueous medium is preferably 80% by weight or more, more preferably 90% by weight or more, and further preferably 100% by weight.
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, from the viewpoint of preventing mixing into the toner, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, can be used. In the present invention, it is preferable to atomize the binder resin using only water without substantially using an organic solvent.

Resin emulsion The resin emulsion for toner of the present invention has a high emulsion concentration. The resin particles in the resin emulsion may contain at least the masterbatch and the binder resin and, if necessary, additives such as a colorant, a release agent, and a charge control agent.

There is no restriction | limiting in particular as a coloring agent, All can use a well-known coloring agent, Specifically, the thing similar to what was used for the said masterbatch can be used.
The content of the colorant is preferably 20 parts by weight or less, and preferably 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin including the resin in the masterbatch, as the total amount with the colorant in the masterbatch. More preferred.
In the present invention, the ratio of the melt viscosity of the master batch at 95 ° C. to the melt viscosity of the binder resin excluding the resin in the master batch (master batch viscosity / binder resin viscosity) is excellent during emulsification. From the viewpoint of achieving emulsifying properties and high emulsion concentration, it is 0.1 to 0.5, preferably 0.15 to 0.45, and more preferably 0.15 to 0.4.

As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; carnauba Plant waxes such as wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; mineral and petroleum systems such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax Wax etc. are mentioned.
The content of the release agent is usually about 1 to 20 parts by weight, preferably 2 to 100 parts by weight of the binder resin including the resin in the master batch 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.
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 including the resin in the master batch.

  The above additives are mixed with a binder resin and a master batch, and then melt kneaded with a kneader. It is important that this melt-kneading is carried out under appropriate conditions so as not to cause the molecular chains of the binder resin to be broken and to cause excessive dispersion of charge control agents, release agents and the like. Specifically, the melt kneading temperature should be performed with reference to the softening point of the binder resin. If the temperature is too low, the molecular chain is severely cut. If the temperature is too high, the charge control agent and the release agent are dispersed. Does not advance. From this point, specifically, the heating temperature of the melt-kneading is preferably 70 to 170 ° C, more preferably 80 to 160 ° C.

  As the melt kneader for performing the melt kneading, it is possible to use a continuous kneader having uniaxial, biaxial or pressure-type multiple rolls, a batch kneader using a roll mill or a kneader type mixer, or an open roll kneader. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type extruder manufactured by Toshiba Machine Co., Ltd., twin screw extruder manufactured by Kay C.K. A shaft extruder, an open roll type continuous kneader or the like is preferably used. Among these, from the viewpoint of dispersibility, a twin-screw extruder, a continuous kneader having a plurality of pressure-type rolls, a kneader mixer, and an open roll kneader are preferable. As the twin screw extruder, a PCM type twin screw extruder manufactured by Ikegai Iron Works is preferable, and as the open roll type kneader, an open roll type kneader manufactured by Mitsui Mining is preferable. As a continuous kneader having a plurality of pressure-type rolls, a pressure-type three-roll continuous kneader is preferable.

The open roll type kneader means a machine having at least two rolls and having an open type melt kneading unit. In the present invention, the kneader having at least two rolls of a heating roll and a cooling roll. Is preferably used. Such an open roll type kneader can easily dissipate kneading heat generated during melt kneading. The open roll kneader is preferably a continuous type from the viewpoint of production efficiency.
In order for the kneaded material to easily stick to the heating roll, the temperature of the heating roll is preferably adjusted to be higher than the softening point of the binder resin, and the temperature of the cooling roll is preferably adjusted to be lower than the softening point of the binder resin. Specifically, the temperature of the heating roll is preferably 80 to 200 ° C, and the temperature of the cooling roll is preferably 20 to 140 ° C.

60-150 degreeC is preferable and the difference of the temperature of a heating roll and a cooling roll has more preferable 80-120 degreeC.
In addition, the temperature of a roll can be adjusted with the temperature of the heat medium passed through the inside of a roll, for example, and the inside of a roll may be divided into two or more and a heat medium with different temperatures may be passed through each roll.
The temperature of the heating roll, particularly the raw material charging side, is preferably higher than the softening point of the binder resin, more preferably 0 to 80 ° C. higher than the softening point, and still more preferably 5 to 50 ° C. Further, the temperature of the cooling roll is preferably lower than the softening point of the binder resin, more preferably 0 to 80 ° C lower than the softening point, and particularly preferably 40 to 80 ° C lower.

  In the present invention, when emulsifying the binder resin, from the viewpoint of improving the emulsification stability of the binder resin, the amount is preferably 5 parts by weight or less, more preferably 0.1 to 3 parts with respect to 100 parts by weight of the resin. 0.5 parts by weight, more preferably 0.1 to 3 parts by weight of surfactant is preferably present. In addition, 100 weight part of resin means the total amount of resin in binder resin and masterbatch.

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 sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium alkyl ether sulfate, sodium alkyl naphthalene sulfonate, sodium dialkyl sulfosuccinate and the like.
Specific examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like.

In the production of the resin emulsion for toner of the present invention, the blending ratio of the master batch and the binder resin is based on 100 parts by weight of the binder resin including the resin in the master batch from the viewpoint of productivity and dispersibility of the colorant. The master batch is preferably 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, and still more preferably 15 to 35 parts by weight.
In this emulsification treatment, it is preferable to add an aqueous alkali solution to the masterbatch and the binder resin, and disperse the masterbatch, the binder 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. Examples thereof include monovalent alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, and organic amine compounds such as alkanolamines.
After dispersion, after neutralizing at a temperature above the glass transition point of the binder resin, a resin dispersion can be produced by phase inversion emulsification by adding an aqueous medium at a temperature above the glass transition point. it can.

The addition rate of the aqueous medium is preferably 0.5 to 50 g / min, more preferably 0.5 to 40 g / min, and still more preferably 0.5 to 100 g per 100 g of resin, from the viewpoint that emulsification can be effectively performed. 30 g / 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 dispersion include the same as the above-described aqueous medium.
The amount of the aqueous medium is preferably 100 to 2000 parts by weight and more preferably 150 to 1500 parts by weight with respect to 100 parts by weight of the binder resin from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation treatment.

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 containing the resin in the masterbatch from the viewpoint of preparing a fine resin 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.
The volume median particle size (D ₅₀ ) of the resin particles in the resin emulsion thus obtained is preferably 0.02 to 2 μm, more preferably, in order to perform uniform aggregation in the subsequent aggregation treatment. It is 0.05-1 micrometer, More preferably, it is 0.05-0.6 micrometer. Here, “volume median particle size (D ₅₀ )” means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size. The measuring method is as described later.

[Electrophotographic toner and method for producing the same]
The electrophotographic toner of the present invention is obtained by agglomerating and coalescing the emulsified particles in the resin emulsion obtained as described above.
Aggregation step The solid content concentration in the resin emulsion is preferably 5 to 50% by weight, more preferably 5 to 43% by weight, in order to cause uniform aggregation by using the toner masterbatch of the present invention. More preferably, it is 5-35 weight%.
In addition, the pH in the system is preferably 2 to 10 at 25 ° C., more preferably 3 to 9, from the viewpoint of achieving both the dispersion stability after emulsification and the cohesiveness of fine particles such as a binder resin. More preferably, it is 4-8.

  In the aggregation step, it is preferable to add an aggregating agent in order to effectively perform aggregation. As the aggregating agent, a quaternary salt cationic surfactant, an organic aggregating agent such as polyethyleneimine, an inorganic aggregating agent such as an inorganic metal salt, an ammonium salt or a divalent or higher metal complex is used. 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 ammonium salts include ammonium halide, ammonium sulfate, ammonium chloride, ammonium acetate, ammonium benzoate, and ammonium salicylate. Examples of quaternary ammonium salts include tetraalkylammonium halides. From the viewpoint of productivity, ammonium sulfate. Preferred examples include ammonium chloride, tetraammonium bromide, and tetrabutylammonium bromide.
The amount of the flocculant used is preferably 30 parts by weight or less, more preferably 25 parts by weight or less, based on 100 parts by weight of the binder resin, from the viewpoint of environmental resistance characteristics of the toner.
The aggregating agent is added after adjusting the pH in the agglomeration process system, and at a temperature below the glass transition point of the resin, preferably at a glass transition point of −10 ° C. or less in order to achieve uniform agglomeration. Is desirable. The flocculant can be added as an aqueous medium solution. Furthermore, it is preferable to sufficiently stir at the time of adding the flocculant and after the addition is completed.
From the viewpoint of high image quality, the volume-median particle size (D ₅₀ ) of the aggregated particles is preferably 1 to 10 μm, more preferably 2 to 10 μm, and even more preferably 2 to 9 μm.

Coalescence process This process is a process of coalescing the aggregated particles obtained in the aggregation process.
In the present invention, the agglomerated particles obtained in the aggregating step are heated to a temperature equal to or higher than the glass transition point of the neutralized binder resin to be united. The heating temperature at this time is preferably not less than the glass transition point of the binder resin and not more than the softening point + 20 ° C., from the viewpoint of the target toner particle size, particle size distribution, shape control, and fusion property of the aggregated particles. Preferably they are glass transition point +5 degreeC or more and softening point +15 degrees C or less, More preferably, they are glass transition point +10 degreeC or more and softening point +10 degrees C or less. The stirring speed is preferably a speed at which the aggregated particles do not settle.

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.
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.
From the viewpoint of high image quality, the volume median particle size (D ₅₀ ) of the coalesced particles is preferably 1 to 10 μm, more preferably 2 to 10 μm, and even more preferably 3 to 9 μm.

Electrophotographic Toner The electrophotographic toner of the present invention is a toner whose image density is remarkably improved by using the master batch or the resin emulsion.
The softening point of the toner is preferably 60 to 140 ° C., more preferably 60 to 130 ° C., and still more 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 addition, the measuring method of a softening point and a glass transition point is based on these measuring methods in resin.

In the electrophotographic toner of the present invention, an auxiliary agent such as a fluidizing agent can be added to the toner particle surface 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 before processing with the external additive. However, when hydrophobic silica is used as the external additive, the desired effect can be obtained by using 1 to 3 parts by weight of hydrophobic silica with respect to 100 parts by weight of the toner before processing with the external additive.

From the viewpoint of high image quality, the volume median particle size (D ₅₀ ) of the toner particles is preferably 1 to 10 μm, more preferably 2 to 9 μm, and even more preferably 3 to 9 μm. Further, the CV values of the agglomerated particles, coalesced particles and toner particles are preferably 30% or less, more preferably 25% or less, and still more preferably 20% or less. Here, the particle size and particle size distribution of the toner particles can be measured by the method described later.
The toner for electrophotography obtained by the present invention can be used as a one-component developer or a two-component developer mixed 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 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]
(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 The temperature was raised to 200 ° C. using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), and the sample cooled to 0 ° C. at a temperature lowering rate of 10 ° C./min from that temperature Measured in ° C / min. When a peak is observed at a temperature 20 ° C. or more lower than the softening point, the peak temperature is measured. When a peak is not observed at a temperature 20 ° C. or higher lower than the softening point, a step is observed. The temperature at the intersection of the tangent line indicating the maximum slope of the curve and the extension line of the base line on the high temperature side of the step is read as the glass transition point. The glass transition point is a physical property peculiar to the amorphous part of the resin, and is generally observed in amorphous polyester, but is observed when amorphous part exists even in crystalline polyester. There is.

[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) Molecular weight distribution measurement Using the following apparatus, chloroform is flowed at a flow rate of 1 ml per minute, 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 this calibration curve, 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)

[Melt viscosity of resin and masterbatch]
The melt viscosity at each temperature was measured by the same method as [Measurement of softening point].
[Particle size of emulsified particles, aggregated particles and coalesced particles]
Using a laser diffraction particle size measuring instrument (HORIBA, “LA-920”), distilled water is added to the measurement cell, and the volume-median particle size (D ₅₀ ) is measured at a concentration at which the absorbance is in the proper range. .

[Toner particle size]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 50 μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the electrolytic solution to a concentration of 5% by weight to obtain a dispersion.
Dispersion conditions: 10 mg of a measurement sample is added to 5 ml of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, then 25 ml of an electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. Prepare a dispersion.
Measurement conditions: By adding the sample dispersion to 100 ml of the electrolyte solution, the particle size of 30,000 particles is adjusted to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured. Determine the volume median particle size (D ₅₀ ).

[Density measurement of printed image]
An image is output on a cardboard using a commercially available printer (manufactured by OKI, “ML5400”), and the image is measured using a colorimeter (“SpectagEye”, manufactured by Gretag-Macbeth), and the light emission conditions are set to a standard light source D50, Color was measured with an absolute white reference in an observation visual field of 2 ° and a density reference DIN NB, and the image density was measured.
[Evaluation of resin emulsion concentration]
Using a colorimeter (SpectroEye, manufactured by Gretag-Macbeth), the resin emulsion is measured with an absolute white reference at a standard light source D50, an observation field of view 2 °, and a density reference DIN NB, and the reflection density is measured. .

Production Example 1 (Production of polyester resin A)
Among the raw material monomers listed in Table 1 below, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxy) (Phenyl) propane, terephthalic acid, and dibutyltin oxide are placed in a 5-liter four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer, and a thermocouple, and reacted at 230 ° C under normal pressure for 5 hours. And further reacted under reduced pressure. After cooling to 210 ° C., fumaric acid and hydroquinone were added and reacted for 5 hours and further reacted under reduced pressure to obtain polyester resin A having physical properties shown in Table 1.

Production Example 2 (Production of polyester resin B)
In the same manner as in Production Example 1, after the raw material monomers listed in Table 1 below, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane, terephthalic acid, dodecenyl succinic acid, and dibutyltin oxide were reacted in a nitrogen atmosphere at 230 ° C. until the reaction rate reached 90%, and then reacted at 8.0 kPa for 1 hour. Went. Thereafter, it is cooled to 210 ° C., trimellitic anhydride is added, and after reacting at normal pressure for 1 hour, the reaction is carried out at 8.0 kPa until the desired softening point is reached. B was obtained.

Production Example 3 (Production of polyester resin C)
A polyester resin C having physical properties shown in Table 1 was obtained in the same manner as in Production Example 1 using the raw material monomers shown in Table 1 below.

Example 1 (Manufacture of masterbatch A)
In the composition ratio shown in Table 2, polyester resin C obtained in Production Example 3, dimethylquinacridone pigment presscake manufactured by Dainichi Seika (red No. 36: solid content 25.8% by weight) and nonionic as a plasticizer Surfactant “Emulgen 430 (manufactured by Kao)” polyoxyethylene oleyl ether (HLB: 16.2) was charged into a Henschel mixer and mixed for 5 minutes to wet. Next, this mixture was charged into a kneader mixer and gradually heated. The resin was melted at approximately 90 to 110 ° C. and kneaded in a state where water was mixed, and kneading was continued at 90 to 110 ° C. for 20 minutes while water was evaporated.
Further, the kneading was continued at 120 ° C. to evaporate the remaining water, followed by dehydration drying. Further, kneading was continued at 120 to 130 ° C. for 10 minutes. After cooling, the mixture was further kneaded with a heated three roll, cooled and coarsely pulverized to obtain a coarsely pulverized product (flushing master; masterbatch A) of the high-concentration colored composition containing the magenta pigment at a concentration of 30% by weight. When this was placed on a slide glass, heated and melted and observed with a microscope, the pigment particles were finely dispersed and no coarse particles were observed. With respect to the obtained master batch A, the melt viscosity at 95 ° C. was measured. The results are shown in Table 2.

Comparative Example 1 (Manufacture of master batch B)
Except that the nonionic surfactant “Emulgen 430 (manufactured by Kao)” polyoxyethylene oleyl ether (HLB: 16.2), which is a plasticizer, was not used at the composition ratio shown in Table 2, the same as in Example 1. Thus, a coarsely pulverized product (flushing master masterbatch B) of a highly concentrated colored composition containing a magenta pigment at a concentration of 30% by weight was obtained. About the obtained masterbatch B, the melt viscosity of 95 degreeC was measured. The results are shown in Table 2.

Examples 2 and 3 and Comparative Example 2
As shown in Table 3, polyester resin, masterbatch, nonionic surfactant and neutralizing agent are added to a 5 liter stainless steel kettle, and dispersed at 95 ° C. with stirring at 200 r / min with a Kai-type stirrer. I let you. After the contents reached 96 ° C. and stirred for 2 hours, deionized water was added dropwise with a chi-type stirrer at 200 r / min and passed through a 200 mesh (mesh size: 105 μm) wire mesh to make the resin fine. A particle emulsion was obtained. Table 3 shows the properties of the obtained resin particle emulsions.

Examples 4 and 5 and Comparative Example 3
[Manufacture of toner for electrophotography]
In a 2 liter container, as shown in Table 4, 400 g of each of the colorant-containing resin emulsions prepared in Examples 2 and 3 and Comparative Example 2 was mixed at room temperature. Next, an aqueous solution in which 27 g of ammonium sulfate (molecular weight: 132.14) as a flocculant was dissolved in 301 g of deionized water as a flocculant was dropped into the mixture over 15 minutes while stirring at 100 r / min with a Kai-type stirrer. did. Thereafter, the mixed dispersion is heated to 55 ° C. over 3 hours and further maintained at 55 ° C. until the volume median particle size (D ₅₀ ) in Coulter Multisizer II becomes 6.0 to 8.0 μm. Went. An aqueous solution in which 28 g of an anionic active agent (Kao Emar E-27) was dissolved in 320 mL of ion-exchanged water was added, the temperature was further raised to 85 ° C. in 30 minutes, and the shape was fixed during this holding step. Changed from aggregated particles to coalesced particles.
Subsequently, it was gradually cooled to room temperature, and colored resin fine particle powder was obtained through a suction filtration step, a washing step, and a drying step. 1.0 part by weight of hydrophobic silica (manufactured by Wacker Chemie, “TS530”, primary number average particle diameter: 8 nm) is externally added with a Henschel mixer to 100 parts by weight of the obtained colored resin fine particle powder. A photographic toner was obtained. Table 4 shows the image evaluation results for the obtained toner.

  According to the present invention, by adding a plasticizer to a masterbatch, a resin emulsion for toner and a toner having high emulsion concentration and image density and good productivity can be obtained.

  The resin emulsion using the toner masterbatch of the present invention can greatly improve the emulsifiability and reduce the generation of coarse particles even when a colorant masterbatch is used. From this point, the resin emulsion of the present invention can remarkably improve the productivity at the time of emulsification and the image density of the toner, so that it can be used for electrophotography, electrostatic recording, electrostatic printing and the like. It can be suitably used for a toner.

Claims (10)

  A master batch for toner comprising a resin, a colorant and a plasticizer.   The toner masterbatch according to claim 1, which is obtained by melt-kneading at least a resin, a colorant, and a plasticizer.   The toner master batch according to claim 1, wherein the toner master batch is a flushing master batch.   The toner masterbatch according to claim 1, wherein the plasticizer is a nonionic surfactant.   The toner masterbatch according to claim 1, comprising 0.2 to 2% by weight of a plasticizer.   The toner masterbatch according to claim 1, wherein the colorant is a quinacridone pigment.   A resin emulsion for toner, which is obtained by dispersing and emulsifying the master batch and the binder resin according to any one of claims 1 to 6 in an aqueous medium.   A method for producing a resin emulsion comprising a step of mixing at least the master batch and the binder resin according to any one of claims 1 to 6, and a step of dispersing and emulsifying the obtained mixture in an aqueous medium. The ratio of the melt viscosity of the master batch to the melt viscosity of the binder resin at 95 ° C. by a flow tester (the viscosity of the master batch / viscosity of the binder resin) is 0.1 to 0.5. Production method.   A method for producing an electrophotographic toner, comprising: a step of obtaining a resin emulsion by the production method according to claim 8; and a step of aggregating and coalescing the emulsion particles in the obtained resin emulsion.   An electrophotographic toner obtained by the production method according to claim 9.