JP4582019B2 - Polymerized toner and method for producing the same - Google Patents

Description

  The present invention relates to a polymerized toner used for development of a copying machine, a facsimile, a printer, and the like by electrophotography and a method for producing the same.

  In an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a printer, an electrostatic latent image formed on a photoreceptor is visualized with a developer (toner). The developer (toner) is mainly composed of colored polymer particles in which a colorant and, if necessary, a charge control agent and a release agent are dispersed in a binder resin.

  The toner is roughly classified into a pulverized toner obtained by a pulverization method and a polymerized toner obtained by a polymerization method according to a method for producing colored polymer particles. In the pulverization method, a prepolymerized thermoplastic resin is used as a binder resin, and other additives such as a colorant, a charge control agent, and a release agent are added, melt-kneaded, pulverized, and classified. By doing so, colored polymer particles are obtained to produce a pulverized toner. In contrast, in the polymerization method, a polymerizable monomer composition containing a polymerizable monomer, a colorant, and other additives such as a charge control agent and a release agent used as necessary, By forming into fine droplets in an aqueous medium and then polymerizing, colored polymer particles are obtained to produce a polymerized toner.

  2. Description of the Related Art In recent years, image forming apparatuses such as copying machines and printers using electrophotography have been rapidly colorized. In color printing, high-definition images such as photographs are also printed. In particular, printing with high resolution and good color reproducibility is required, and high-quality color toner that can meet the demand is required. Yes. Spherical toner has good transferability and dot reproducibility, and is suitable for color printing. Since polymerization methods such as suspension polymerization, dispersion polymerization, and emulsion polymerization can efficiently produce spherical toner. A toner by polymerization (polymerized toner) is suitable for color printing.

  On the other hand, in recent years, regulations relating to environmental hygiene have been strengthened. For such image forming apparatuses, the polymerizable monomer remaining in the toner (which volatilizes when the toner is fixed by heat) ( In the present invention, the effects on the human body and odor of low molecular weight components such as “residual monomer”) and other volatile organic substances (hereinafter also referred to as “residual VOC” in the present invention) are problematic. It has become. In addition, if a large amount of low molecular weight components remain in the toner, there is a problem that offset is likely to occur or toner filming is likely to occur on the surface of a member of an image forming apparatus such as a photoreceptor or a developing blade. Is likely to occur.

Therefore, in order to produce a toner with little residual monomer and residual VOC, a method for removing the residual monomer and residual VOC from the colored polymer particles after polymerization has been proposed. Removal of residual monomers and residual VOCs is more difficult with polymerized toners than with pulverized toners for the following reasons. In the pulverization method, these components can be removed by using only a binder resin or the like before adding a colorant or other additives. On the other hand, in the polymerization method, colored polymer particles are formed simultaneously with the polymerization, so that the colored polymer in a state where the binder resin , which is a polymerized polymerizable monomer, and the colorant and other components coexist. It is necessary to remove these components from the particles. Residual monomer and residual VOC are components other than the binder resin (a colorant, a charge control agent, and a release agent, etc.) are easily absorbed, hard dividing removed by as compared with the case of only the binder resin. Furthermore, if the toner is heated too much for a long time or at a high temperature, the quality of the obtained toner is deteriorated due to the aggregation of the colored polymer particles or the deterioration of the colorant and other additives in the colored polymer particles. It tends to decline.

In recent years, there has been an increasing demand for toners to lower the minimum fixing temperature in response to on-demand printing, higher speed, and full color. Furthermore, because full-color printing is performed by superimposing four colors, it is required that each color toner has high printing durability even in various environments such as NN (room temperature and humidity) and HH (high temperature and high humidity) environments. ing. In such a toner, it is extremely difficult to remove residual monomer and residual VOC without causing deterioration of the toner quality due to aggregation of colored polymer particles and deterioration of each component in the colored polymer particles. It was.

  It has been conventionally proposed to remove residual monomers and residual VOCs from an aqueous dispersion containing colored polymer particles obtained by a polymerization method by stripping treatment.

  Patent Document 1 discloses a method of removing these low molecular weight components by a steam stripping method in which saturated water vapor is blown into an aqueous dispersion containing colored polymer particles obtained by a polymerization method. However, this method has a problem that the colored polymer particles tend to aggregate due to the shearing force when saturated water vapor comes into contact with the colored polymer particles.

In Patent Document 2, an aqueous dispersion containing colored polymer particles obtained by a polymerization method is placed in a distillation apparatus, and nitrogen gas is 4.1 kg / hour (converted to the nitrogen gas flow rate of the present invention) in the gas phase portion thereof. Then, a method for producing a toner is disclosed which includes a step of stripping by circulating at a pressure of 4.2 L / hr · kg) and reducing the pressure. However, even when this method is used, the efficiency of removing low molecular weight components is insufficient, and further, there is a problem that the printing durability of the obtained polymerized toner is deteriorated. In addition, since a large amount of gas such as nitrogen is used , there is a problem that energy consumption increases.

  Patent Document 3 discloses a method for producing a toner by performing a stripping process by injecting nitrogen gas at an atmospheric pressure of 101 kPa into an aqueous medium containing colored polymer particles obtained by a polymerization method. Yes. According to this method, the residual monomer can be efficiently removed, but the removal efficiency of residual VOC is insufficient. If the flow rate of nitrogen is increased to improve the efficiency, the liquid level of the aqueous medium is reduced. There was a problem that a large amount of foam was easily generated, and stable operation could not be performed when the foam was generated.

JP-A-5-1000048 JP 2001-92180 A JP 2004-271816 A

  The problem of the present invention is that the toner has excellent high-temperature storage stability, does not cause bad odor when printing, does not deteriorate the surrounding environment, and durability when performing durable printing particularly under high temperature and high humidity. The present invention provides a polymerized toner excellent in the resistance to light and a method for producing such a toner stably and efficiently.

As a result of earnestly examining the method for removing residual monomer and residual VOC by stripping treatment from an aqueous medium containing colored polymer particles obtained by a polymerization method,
Under certain decompression conditions
While stirring
By stripping process in which air or inert gas is injected at a specific flow rate,
It has been found that the above problem can be solved by setting the ether component in the residual VOC to a specific level.

Thus, according to the present invention,
A polymerizable monomer composition containing a polymerizable monomer and a colorant is polymerized in an aqueous medium in the presence of an organic peroxide as a polymerization initiator, and an aqueous dispersion containing colored polymer particles is obtained. And polymerization obtained through a stripping step of injecting air or an inert gas under the surface of the aqueous dispersion while stirring in an evaporator having a gas phase pressure of 5 to 80 kPa. A toner, wherein the organic peroxide is represented by the following formula (1):
R—CO—O—O—R ′ (1)
[In the formula, R is an alkyl group having 6 or less carbon atoms, and R ′ is an alkyl group having 8 or less carbon atoms. ]
There is provided a polymerized toner, which is a non-aromatic peroxyester of the present invention, wherein the content of the ether component of the polymerized toner is less than 100 ppm, and a method for producing such polymerized toner.

In the stripping process, the aqueous medium is an oil-based antifoaming agent, mineral oil-based antifoaming agent, polyether-based antifoaming agent, polyalkylene glycol type nonionic surfactant, and oil and polyalkylene glycol type nonionic surfactant. It is preferable to contain at least one non-silicone antifoaming agent selected from the group consisting of emulsions containing an agent. The polymerization initiator is preferably a non-aromatic peroxyester. The styrene content of the polymerized toner is preferably less than 50 ppm. The polymerizable monomer composition preferably contains 0.01 to 3 parts by weight of a molecular weight modifier with respect to 100 parts by weight of the monovinyl monomer which is the main component of the polymerizable monomer. . Polymerizable monomer composition, as a molecular weight modifier, Chiazoruchio compounds, thiuram compounds, and preferably contains at least one compound selected from the group consisting of dithiocarbamic acid compound.

  According to the present invention, the toner has excellent high-temperature storage stability, does not generate bad odor when printing, does not deteriorate the surrounding environment, and has durability especially when performing durable printing under high temperature and high humidity. An excellent polymerized toner and a method for producing such a polymerized toner stably and efficiently are provided.

Hereinafter, the polymerized toner of the present invention and the production method thereof will be described.
First, a polymerizable monomer, a colorant, and other additives as necessary are mixed to obtain a polymerizable monomer composition. This polymerizable monomer composition was placed in an aqueous medium, a polymerization initiator was added, after droplet formation, polymerization row sparse, aqueous dispersion of the colored polymer particles are obtained. The obtained aqueous dispersion of colored polymer particles is stripped under specific conditions to remove residual monomers and residual VOC in the colored polymer particles.
Thereafter, the obtained colored polymer particles are washed, dehydrated, and further dried, classified as necessary, and, if necessary, an external additive and / or a carrier are added to obtain an ether component content. A polymerized toner that is less than 100 ppm is obtained.

(1) Polymerizable monomer composition A polymerizable monomer, a colorant, and other additives used as necessary are mixed to obtain a polymerizable monomer composition. The colorant and other additives are preferably mixed with the polymerizable monomer so as to be dissolved or dispersed as uniformly and finely as possible.

In the present invention, the polymerizable monomer refers to a polymerizable compound.
A monovinyl monomer is used as the main component of the polymerizable monomer. Examples of the monovinyl monomer include styrene; styrene derivatives such as vinyl toluene and α-methylstyrene; acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid 2 Acrylic esters such as ethylhexyl and dimethylaminoethyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and dimethylaminoethyl methacrylate; acrylonitrile Derivatives of acrylic acid such as methacrylonitrile, acrylamide and methacrylamide, and derivatives of methacrylic acid; olefins such as ethylene, propylene and butylene; vinyl chloride and vinylidene chloride And vinyl halides such as vinyl fluoride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone and methyl isopropenyl ketone. And nitrogen-containing vinyl compounds such as 2-vinylpyridine, 4-vinylpyridine, and N-vinylpyrrolidone. These monovinyl monomers may be used alone or in combination. Of these, styrene, styrene derivatives, and acrylic acid or methacrylic acid derivatives are preferably used as monovinyl monomers.

  The monovinyl monomer is preferably selected such that the polymer obtained by polymerizing the monovinyl monomer has a glass transition temperature (hereinafter referred to as Tg) of 80 ° C. or lower. The Tg of the polymer can be adjusted to a desired range by selecting an appropriate monovinyl monomer singly or in combination of two or more.

  In order to improve hot offset of the obtained polymerized toner, it is preferable to use any crosslinkable polymerizable monomer together with the monovinyl monomer as the polymerizable monomer. A crosslinkable polymerizable monomer means a polymerizable monomer having two or more polymerizable functional groups. Examples of the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; diacrylate compounds such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; N, N-divinyl. And other divinyl compounds such as aniline and divinyl ether; and compounds having three or more vinyl groups. These crosslinkable polymerizable monomers can be used alone or in combination of two or more. The crosslinkable polymerizable monomer is usually used in an amount of 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, based on 100 parts by weight of the monovinyl monomer.

  Further, it is preferable to use a macromonomer as a part of the polymerizable monomer because the balance between the storage stability and the fixing property at a low temperature of the resulting polymerized toner is improved. The macromonomer has a polymerizable carbon-carbon unsaturated double bond at the end of the molecular chain, and is a reactive oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000. The macromonomer is preferably a polymer that has a higher Tg by homopolymerizing it than the Tg of the polymer obtained by polymerizing the monovinyl monomer. The amount of the macromonomer used is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the monovinyl monomer. .

  In the present invention, a colorant is used, but when a color toner (usually, four types of toners are used: black toner, cyan toner, yellow toner, and magenta toner), a black colorant, a cyan colorant, and a yellow toner are used. A colorant and a magenta colorant can be used, respectively.

  As the black colorant, carbon black, titanium black, and pigments such as magnetic powders such as iron oxide zinc and iron oxide nickel can be used.

  As the cyan colorant, for example, a copper phthalocyanine compound, a derivative thereof, and an anthraquinone compound can be used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17, 17: 1 and 60, etc. Is stable and has coloring power. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 17: 1, and the like, preferably copper phthalocyanine compounds such as C.I. I. Pigment Blue 15: 3 is more preferable.

  As the yellow colorant, for example, azo pigments such as monoazo pigments and disazo pigments, and compounds such as condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Yellow 3, 12, 12, 13, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 155, 180, 181, 185, 186, and the like. Since the polymerization stability is good and there is coloring power, C.I. I. Monoazo pigments such as CI Pigment Yellow 3, 15, 65, 73, 74, 97, and 120 are preferable; I. Pigment Yellow 74 is more preferable.

  Examples of the magenta colorant include compounds such as monoazo pigments, azo pigments such as disazo pigments, and condensed polycyclic pigments. Specifically, C.I. I. Pigment Red 31, 48, 57: 1, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 150, 163, 170, 184, 185, 187, 202, 206, 207, 209, 251 and C . I. Pigment Violet 19 etc. are mentioned. Since the polymerization stability is good and there is coloring power, C.I. I. Pigment Red 31, 48, 57: 1, 58, 60, 63, 64, 68, 112, 114, 146, 150, 163, 170, 185, 187 Monoazo pigments such as No. 206 and No. 207 are also preferred.

  The amount of the colorant used is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the monovinyl monomer.

In addition to the polymerizable monomer and the colorant, other additives such as a charge control agent, a molecular weight adjusting agent, and a release agent are added to the polymerizable monomer composition as necessary. May be.

  As the charge control agent, various positively chargeable or negatively chargeable charge control agents can be used. For example, a metal complex of an organic compound having a carboxyl group or a nitrogen-containing group, a metal-containing dye, and a non-resin charge control agent such as nigrosine; a quaternary ammonium group or quaternary ammonium base-containing copolymer, a sulfonic acid group or a sulfonic acid Base-containing copolymers, charge control resins such as carboxylic acid groups or carboxylate-containing copolymers, and the like can be used. The charge control agent preferably contains a charge control resin, and more preferably only the charge control resin, because the printing durability of the toner becomes good. As the charge control resin, a quaternary ammonium group or quaternary ammonium base-containing copolymer, a sulfonic acid group or a sulfonate group-containing copolymer is more preferable. The usage-amount of a charge control agent is 0.01-10 weight part normally with respect to 100 weight part of monovinyl monomers, Preferably it is 0.03-8 weight part.

  It is preferable to use a molecular weight modifier as another additive. Examples of the molecular weight modifier include t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and mercaptan compounds such as 2,2,4,6,6-pentamethylheptane-4-thiol; tetramethylthiuram monosulfide, Tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide, N, N'-dimethyl-N, N'-diphenylthiuram disulfide, N, N'-dioctadecyl-N, N'- Thiuram compounds such as diisopropyl thiuram disulfide; pentamethylene dithiocarbamic acid piperidine salt, pipecolyl dithiocarbamic acid pipecoline salt, sodium dimethyldithiocarbamate, diethyldithiocarbamic acid Thorium, sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, N- ethyl -N- phenyl dithiocarbamate, zinc, dithiocarbamic acid compounds tellurium diethyldithiocarbamate and the like; and the like. Of these molecular weight regulators, mercaptan compounds and thiuram compounds are preferred, and thiuram compounds are particularly preferred. The amount of the molecular weight modifier is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 1 part by weight, and particularly preferably 0.1 to 0.5 part by weight with respect to 100 parts by weight of the monovinyl monomer. It is. If the amount is less than the above range, the effect of adjusting the molecular weight cannot be obtained.

  Moreover, it is preferable to add a mold release agent as another additive. This is because the releasability of the polymerized toner from the fixing roll during fixing can be improved. The release agent is not particularly limited as long as it is generally used as a toner release agent. Low molecular weight polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; End-oxidized low molecular weight polypropylene, low-molecular-weight end-modified polypropylene with molecular ends substituted with epoxy groups, block polymers of these and low-molecular weight polyethylene, molecular-end oxidized low-molecular weight polyethylene, low-molecular weight polyethylene with molecular ends replaced with epoxy groups, and these And end-modified polyolefin waxes such as block polymers of low molecular weight polypropylene; plant natural waxes such as candelilla, carnauba, rice, wood wax, and jojoba; stones such as paraffin, microcrystalline, and petrolactam Waxes, and modified waxes thereof; mineral waxes such as montan, ceresin and ozokerite; synthetic waxes such as Fischer-Tropsch wax; and pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, pentaerythritol tetrastearate, and pentaerythritol And polyvalent alcohol esterified products such as dipentaerythritol esters such as pentaerythritol esters such as tetralaurate, dipentaerythritol hexamyristate, dipentaerythritol hexapalmitate, and dipentaerythritol hexalaurate. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Among these release agents, the endothermic peak temperature measured from the DSC curve at the time of temperature rise using a differential scanning calorimeter is 30 to 150 ° C, preferably 50 to 120 ° C, more preferably 60 to 100 ° C. A polyhydric alcohol esterified product such as pentaerythritol ester in the range and dipentaerythritol ester having the same endothermic peak temperature in the range of 50 to 80 ° C. is particularly preferable because of excellent balance of fixing and peeling properties of the resulting polymerized toner. . The amount of the release agent used is preferably 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight with respect to 100 parts by weight of the monovinyl monomer.

  In the preparation of the polymerizable monomer composition, it is preferable to add the other additives described above after the colorant is dissolved or sufficiently dispersed in the polymerizable monomer. Various known methods can be adopted as the method for dispersing the colorant in the polymerizable monomer, but a method using a media type disperser is particularly preferable, and a media type disperser provided with a media separation screen is used. The method used is particularly preferred. The above-mentioned other additives are added to the obtained mixture to obtain a polymerizable monomer composition.

(2) Droplet formation step After the polymerizable monomer composition obtained as described above is dispersed in an aqueous medium, a polymerization initiator is added, and then a droplet of the polymerizable monomer composition is formed. Is formed. The method for forming droplets is not particularly limited. For example, an in-line type emulsifier / disperser (for example, “Milder” manufactured by Ebara Seisakusho), a high-speed emulsifier / disperser (for example, manufactured by Special Machine Industries, product name “ TK homomixer MARK II type ") and the like capable of strong stirring.

  The aqueous medium in the present invention is a medium containing water as a main component, and may contain an organic solvent that dissolves in water such as alcohol as a subcomponent. The aqueous medium preferably contains a dispersion stabilizer before the droplet formation described below. Dispersion stabilizers include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide And metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; and inorganic compounds that dissolve in acids or alkalis such as metal compounds. Furthermore, organic compounds such as water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and gelatin; anionic surfactants; nonionic surfactants; and amphoteric surfactants may be used in combination. The said dispersion stabilizer can be used 1 type or in combination of 2 or more types.

  The dispersion stabilizer is preferably a metal compound, more preferably a colloid of a poorly water-soluble metal hydroxide. By using such a dispersion stabilizer, it is possible to sharpen the particle size distribution of the polymerizable monomer composition droplets (and consequently the particle size distribution of the obtained colored polymer particles or polymerized toner). It is possible to reduce the coalescence of the colored polymer particles during the polymerization and in the stripping process, and further, since the residual amount of the dispersion stabilizer after washing is small, the resulting polymerized toner reproduces the image clearly. It is preferable because it can reduce environmental stability.

  In the present invention, the polymerizable monomer composition obtained as described above is dispersed in an aqueous medium, a polymerization initiator is added, and then a droplet of the polymerizable monomer composition is formed. .

  In the present invention, an organic peroxide is used as the polymerization initiator, and preferably a peroxy ester is used. By using the above polymerization initiator, the polymerizable monomer is efficiently polymerized. As a result, it is possible to obtain a polymerized toner that has a low content of styrene, which is the main component of the polymerizable monomer, is excellent in storage stability, and does not generate bad odor and does not deteriorate the surrounding environment when printing is performed.

  In polymerization using an organic peroxide as a polymerization initiator, for example, when it is a peroxy ester, when the peroxy ester undergoes thermal decomposition, it first decomposes into the corresponding alcohol radical and carboxylic acid radical, and then these The polymerization reaction proceeds by adding radicals, alkyl radicals generated by decarboxylation of carboxylic acid radicals, and the like to the monomer. However, these radicals may generate by-products such as various ether components due to recombination and hydrogen abstraction.

  On the other hand, among organic peroxides, particularly organic peroxides that have a high risk of ignition by impact or heating, it is necessary to dilute them by adding a diluent. When such an organic peroxide is used as a polymerization initiator, the presence of a diluent tends to increase the volatile substances remaining in the resulting colored polymer particles. In addition, when an organic peroxide containing a large amount of an organic peroxide different from the main organic peroxide as an impurity is used as the polymerization initiator, the impurity organic peroxide is suitable as the main organic peroxide. Since the reaction conditions are different, the initiator efficiency is lowered, and the polymerizable monomer and ether component remaining in the resulting colored polymer particles are likely to increase.

Among organic peroxides, peroxyesters are preferred because the initiator efficiency is good and the remaining polymerizable monomers can be reduced, and non-aromatic peroxyesters, that is, those having no aromatic ring. Oxyesters are more preferred.
Further, the organic peroxide is represented by the following formula (1)
R—CO—O—O—R ′ (1)
(Wherein R and R ′ represent an alkyl group), and more preferably a peroxy ester represented by R in the formula is preferably an alkyl group having 6 or less carbon atoms, more preferably 5 or less, isopropyl, 1-methylpropyl, 1-ethylpropyl, 1-methylbutyl, 2-methylbutyl, 3- A secondary alkyl group such as methylbutyl and 1-ethylpropyl is more preferable, and 1-methylpropyl and 1-ethylpropyl are particularly preferable. In formula (1), R ′ is preferably an alkyl group having 8 or less carbon atoms, more preferably t-butyl and t-hexyl, and particularly preferably t-butyl. Specific examples of the peroxyester of the formula (1) include t-hexylperoxypivalate (t-hexylperoxy-2,2-dimethyl-acetate), t-butylperoxy-2-ethylbutanoate ( t-butylperoxydiethyl acetate) , t-butylperoxy-2-methylbutanoate and the like.

  In the present invention, the molecular weight of the main component of the organic peroxide is preferably 205 or less, more preferably 170 or more and 200 or less, and further preferably 175 or more and 195 or less. In the present invention, the purity of the organic peroxide represents the weight percent of the organic peroxide as the main component with respect to the organic peroxide, preferably 90% or more, more preferably 92% or more, and still more preferably, 95% or more.

  The one-hour half-life temperature of the organic peroxide is preferably 70 ° C. or higher and 95 ° C. or lower, more preferably 75 ° C. or higher and 95 ° C. or lower because a polymerized toner having good printing durability can be obtained. 85 ° C. or more and 95 ° C. or less is more preferable. Here, the half-life temperature is an index representing the likelihood of cleavage of the polymerization initiator, and when the polymerization initiator is held at a certain temperature, it decomposes and the amount of the original initiator after a certain time. The temperature which becomes 1/2 is shown. For example, at a one-hour half-life temperature, this constant time is a half-life temperature of one hour.

  By using the above polymerization initiator, it is possible to reduce the amount of unreacted polymerizable monomer remaining in the colored polymer particles obtained, the ether component by-produced by the polymerization initiator, and the like. As a result, the toner of the present invention has excellent high-temperature storage stability, and when printing is performed, no bad odor is generated and the surrounding environment is not deteriorated, and when durable printing is performed under high temperature and high humidity. A toner having excellent durability can be obtained.

  The amount of the polymerization initiator used is preferably 0.1 to 15 parts by weight and more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the monovinyl monomer. When it is in the above range, the polymerization is efficiently performed, and the residual monomer and the residual VOC in the colored polymer are reduced. The polymerization initiator may be added after the polymerizable monomer composition is dispersed in the aqueous medium and before the droplet formation, but the aqueous initiator containing the polymerizable monomer composition after the droplet formation is used. It may be added to the medium.

  The method for forming droplets is not particularly limited. For example, an (in-line type) emulsifying disperser (manufactured by Ebara Manufacturing Co., Ltd., product name “Milder”), a high-speed emulsifying disperser (manufactured by Tokushu Kika Kogyo Co., Ltd., product name “T. K. Homomixer MARK Type II ") etc. is used by stirring the aqueous medium containing the polymerizable monomer composition using an apparatus capable of strong stirring.

(3) Polymerization Step Colored polymer particles are obtained by raising the temperature of the aqueous dispersion containing droplets of the polymerizable composition obtained in the droplet formation step and performing polymerization. The polymerization temperature of the polymerizable monomer composition (the highest temperature reached by the aqueous dispersion) is preferably 50 ° C. or higher, more preferably 60 to 120 ° C. The reaction time of the polymerization is preferably 1 to 20 hours, more preferably from 2 to 15 hours.

The colored polymer particles obtained in the above step may be used as a polymerized toner as it is or after adding an external additive after acid washing, filtration, washing with water, and drying described later. Using colored polymer particles as a core layer and forming a shell layer different from the core layer on the outer side, so-called core-shell type (or “capsule type”) colored polymer particles are obtained, and then washed with acid and filtered. -After washing with water and drying, it is preferable to use the polymer toner as it is or after adding an external additive. Core-shell type colored polymer particles balance the balance between lowering the fixing temperature and preventing aggregation during storage by coating the core layer made of a material with a low softening point with a material having a higher softening point. be able to. In the present invention, when preparing the core-shell type colored polymer particles, the colored polymer particles obtained as described above are used as the core particles, and the polymerizable monomer used in the preparation is used as the core polymerizability. monomeric, polymerizable monomer composition for core polymerizable monomer composition gutter Unado, what and processes related to the core preparation may be represented by the word "core", while the shell For example, a polymerizable monomer for use in a shell is referred to as a polymerizable monomer for use in shells, and the term “for a shell” may be used to describe an object or process related to shell preparation.

  There is no restriction | limiting in particular as a method of manufacturing a core shell type colored polymer particle using the said colored polymer particle mentioned above, It can manufacture by the conventional method. An in situ polymerization method and a phase separation method are preferable from the viewpoint of production efficiency. The core-shell type colored polymer particles are produced by the in situ polymerization method by polymerizing droplets of the polymerizable monomer composition as described above, and the polymerization is almost completed (preferably the polymerization conversion rate is 90%). %), When the colored polymer particles forming the core layer are formed, a polymerizable monomer (shell polymerizable monomer) for forming a shell layer in the aqueous medium The core-shell type colored polymer particles can be obtained by adding a polymerization initiator for the shell and polymerization.

  As the polymerizable monomer for the shell, those similar to the polymerizable monomer for the core described above can be used. As polymerization initiators for the shell, persulfate metal salts such as potassium persulfate and ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) propionamide), and 2, Water-soluble polymerization initiators such as azo initiators such as 2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide) can be mentioned. .

(4) Stripping treatment An aqueous medium (referred to as an aqueous dispersion of colored polymer particles) containing the colored polymer particles dispersed in (3) is obtained, and then subjected to a stripping treatment. When performing the stripping treatment, it is preferable to further add a dispersion stabilizer, and the same kind as the dispersion stabilizer used for forming the colored polymer particles is preferable. The stripping treatment is performed by putting an aqueous medium containing colored polymer particles into an evaporator, depressurizing the gas phase, and injecting air or inert gas into the aqueous medium from below the liquid surface. By this step, residual monomer and residual VOC dissolved in the colored polymer particles or the aqueous medium can be removed and reduced.

The stripping treatment of the present invention is performed while stirring the dispersion of colored polymer particles in an evaporator. The vapor phase part of the evaporator is decompressed, and the pressure is 5 to 80 kPa. The flow rate of the gas consisting of air or inert gas is preferably 0.005 to 10 L / hr · kg.

  During the stripping process, an aqueous medium can be additionally added to the aqueous dispersion containing the colored polymer particles, and the amount thereof is based on 100 parts by weight of the aqueous dispersion containing the colored polymer particles. Usually 1 to 200 parts by weight, preferably 5 to 100 parts by weight. Within this range, the steps such as washing and filtration after stripping can be carried out with good productivity while obtaining the effects of the present invention.

  During the stripping treatment, foaming may occur on the surface of the aqueous dispersion of colored polymer particles, and foam may be generated. If the bubbles become excessive and overflow the evaporator, problems such as contamination of the gas circulation line occur. In order to suppress foaming, emulsified oil and fat-based antifoaming agent, mineral oil-based antifoaming agent, polyether-based antifoaming agent, polyalkylene glycol type nonionic surfactant, oil and fat and polyalkylene glycol type nonionic surfactant And at least one non-silicone antifoaming agent selected from the group consisting of an emulsion containing mineral oil and a polyalkylene glycol type nonionic surfactant is added to the aqueous dispersion containing colored polymer particles. It is preferable. Among these non-silicone defoamers, mineral oil defoamers, polyalkylene glycol-type nonionic surfactants, fats and polyalkylene glycol-type nonions are superior because of the defoaming effect and the properties of the resulting polymerized toner. Emulsions containing a surfactant are preferred.

  The mineral oil-based antifoaming agent is a modified hydrocarbon oil based on mineral oil, and examples thereof include a product name “antifoaming agent DF714S” manufactured by Japan PCM Corporation. The polyalkylene glycol type nonionic surfactant is a nonionic surfactant comprising a polyethylene glycol type nonionic surfactant and a polyoxyethylene / polyoxypropylene block copolymer. For example, the product name “Sannopco” SN deformer 180 "(a foam suppressor comprising a polyoxyalkylene type nonionic surfactant). The emulsion containing fats and oils and a polyalkylene glycol type nonionic surfactant is obtained by emulsifying fats and oils with a polyalkylene glycol type nonionic surfactant. For example, a product name “SN deformer 1407K manufactured by San Nopco Co., Ltd.” "(Foam suppressant made of an emulsion of oils and fats, polyethylene glycol type nonionic surfactants, etc.). Examples of polyether antifoaming agents include polyether type surfactants such as product names “Adecanol LG-51” and “Adecanol LG-109” manufactured by Asahi Denka Co., Ltd., and product names “IP Special polyether compounds such as “Deformer U-510” can be used.

  The amount of the non-silicone antifoaming agent used is preferably 0.01 to 1 part by weight, more preferably 0.05 to 0.5 part by weight, based on 100 parts by weight of the polymerizable monomer composition used. More preferably, it is 0.07-0.3 weight part. If the amount of the antifoaming agent used is small, it may be difficult to obtain a sufficient antifoaming effect. If the amount used is large, the environmental properties of the resulting polymerized toner, particularly printing properties such as durability in an H / H environment, may be obtained. It tends to decline.

When the residual monomer and residual VOC in the colored polymer particles is below a desired amount and may be terminated stripping, during printing of the polymerized toner obtained odors etc. and the recent strict environmental regulations From the viewpoint, it is preferable that the total amount of residual monomer and residual VOC in the colored polymer particles after the stripping treatment is 50 ppm or less. Here, the residual monomer to be removed is a polymerizable monomer, and includes a polymerizable monomer for shell. The residual VOC to be removed is the volatile organic compound in the organic solvent in the aqueous medium, the remaining polymerization initiator, and other additives used in the preparation process of the polymerizable monomer composition and the polymerization process. And volatile organic compounds produced by these decomposition reactions.

The gas to be injected is air or an inert gas as described above, but nitrogen is preferable. The flow rate of the gas to be injected is preferably 0.005 to 10 L / per unit amount of an aqueous dispersion containing colored polymer particles (including an additional aqueous medium, which is an object of stripping treatment). hr · kg, more preferably 0.01 to 5 L / hr · kg, and still more preferably 0.02 to 2 L / hr · kg. Below this range, the rate of removal of residual monomer and residual VOC is not sufficient. On the contrary, if the amount is large, foaming increases and it becomes difficult to continue the stripping process, and the aggregation of the colored polymer particles increases. On the other hand, the use of a large amount of gas increases the energy consumption. End up. It is preferable that the gas flow rate be gradually increased as the stripping process proceeds. The ratio of the average flow rate in the latter half of the stripping process to the average flow rate in the first half of the stripping process is preferably in the range of 1.05 to 10, more preferably 1.2 to 6, and 1.5 to 5 Particularly preferred.

  The stripping treatment of the present invention is performed under a reduced pressure of 5 to 80 kPa in the vapor phase part (absolute pressure) of the evaporator. This pressure is preferably 10 to 75 kPa, more preferably 15 to 70 kPa, and even more preferably 30 to 65 kPa. The temperature (maximum temperature) of the internal solution of the evaporator at the time of stripping is usually 20 to 95 ° C, preferably 50 to 95 ° C, more preferably 70 to 90 ° C. The time required for stripping is not particularly limited, but is usually 30 minutes to 24 hours, preferably 2 to 16 hours, and particularly preferably 4 to 12 hours. Within these ranges, the stripping process is efficient, the colored polymer particles are agglomerated, and the aqueous medium and other volatile components from the inside of the aqueous medium including the colored polymer particles in the evaporator boil. It is possible to suppress the foaming caused by the above and to perform a stable stripping process.

  During the stripping treatment, foaming occurs on the surface of the aqueous dispersion of colored polymer particles, but the foam level does not exceed 95% based on the height of the evaporator, and the foam level is reduced through the stripping treatment. It is preferable to control stripping conditions so that the range of fluctuation is within 10% of the range. In the present invention, the bubble level is expressed as the bubble level (%) by using the height of the evaporator as a reference (100%) and displaying the bubble height from the bottom as a percentage. If the level of the dispersion is at 60% of its height in the evaporator, the foam level will exceed 60%. In order not to contaminate the gas circulation line or the condenser with bubbles, it is preferable that the bubble level not exceed 95% throughout the stripping process, more preferably not more than 93%. To. From the viewpoint of stripping processing efficiency, it is not preferable that the foam level is too low. That is, it is preferable to maintain the bubble level, and it is more preferable to maintain the variation range of the bubble level within 10% of the evaporator height in the range.

  An apparatus used in the stripping process performed in the present invention will be described using an example. As shown in FIG. 1, the apparatus is provided with a gas circulation line 6-7-8-9-10-11-5-3 outside, and this gas circulation line includes a blower 5, a volatile substance removing device 10, a condensing unit. And a condensing tank 8. The evaporator 1 is a container having a strength that can withstand the reduced pressure required for the stripping process, and may be the same as or different from the container (reactor) used in the polymerization step. The evaporator 1 includes a stirring blade 2 for stirring the dispersion of the colored polymer particles inside. Moreover, you may equip the outer surface of the evaporator 1 with the jacket (not shown) for heating and cooling at the time of superposition | polymerization, and heating by a stripping process.

  A blower 4 is used to blow air or an inert gas gas from the gas source (not shown) through the gas blowing tube 3 into the lower surface of the evaporator 1. The temperature inside the evaporator 1 is raised to a predetermined temperature while stirring the internal liquid, and then gas is blown into the evaporator 1 from the blower 4 through the opening of the blower tube 3. Part of the aqueous medium of the dispersion, residual monomer and residual VOC are led to the condenser 7 through the gas circulation line 6 and then to the condensation tank 8. The aqueous medium condensed in the condensation tank 8 and liquefied, the residual monomer, and the liquid components of residual VOC are recovered there (recovery line not shown). The gas component is guided to the volatile substance removing device 10 through the gas circulation line 9. The volatile substance removing device 10 is, for example, an adsorption tower filled with activated carbon or a bubbling device in which cold water is stored, where residual monomer and residual VOC are removed. Thereafter, gaseous components such as air and inert gas are circulated from the gas circulation line 11 through the blower 5 and reused.

  As a stirring condition in the stripping treatment, the stirring speed is preferably 1 to 50 rotations / minute, and more preferably 2 to 40 rotations / minute. The stirring blade 2 is not particularly limited, but a stirring blade such as a wide paddle blade, a wide inclined blade, a bull margin blade and its deformation blade, a full zone blade, and a wall wetter blade is preferable. Further, as disclosed in Japanese Patent Application Laid-Open No. 2001-117272, a part of the stirring blade may be protruded on the liquid surface.

(5) Polymerized toner After completion of the stripping treatment, the colored polymer particles are filtered out from the aqueous dispersion containing the colored polymer particles according to a conventional method for producing polymerized toner (filtered off), and a dispersion stabilizer. Removal, dehydration, and drying are performed to obtain dried colored polymer particles. The step after filtration is preferably repeated several times as necessary. The removal of the dispersion stabilizer is generally performed by adding an acid such as sulfuric acid and dissolving the dispersion stabilizer.

  The colored polymer particles have a ratio Dv / Dp between the volume average particle diameter (Dv) and the number average particle diameter (Dp) of preferably 1.0 to 1.3, more preferably 1.0 to 1. .2. When Dv / Dp exceeds these ranges, blurring may occur in the resulting image using the polymerized toner, and transferability, print density, and resolution may decrease. The volume average particle size and the number average particle size of the colored polymer particles can be measured using, for example, a particle size measuring device (product name Multisizer, manufactured by Beckman Coulter, Inc.).

  The colored polymer particles can be used as they are for the polymerization toner as they are for the development of electrophotography, but the colored polymer particles are mixed with an external additive and other particles as necessary. It is preferable to attach or embed an external additive on the surface of the colored polymer particles. This is because the chargeability, fluidity, storage stability and the like when used as a polymerized toner can be adjusted and improved. In this case, it is preferable to use a high-speed stirrer such as a Henschel mixer. Examples of the external additive include inorganic particles and organic resin particles such as silica, aluminum oxide, and titanium oxide that are usually used for the purpose of improving fluidity and chargeability.

The polymerized toner of the present invention has a low residual VOC, and when attention is paid to the content of the ether component as a component thereof, it is usually less than 500 ppm, preferably less than 400 ppm, more preferably less than 100 ppm, most preferably less than 50 ppm. The lower limit is not particularly limited, but is preferably 2 ppm or more. In the present invention, it is less than 100 ppm. Further, the toner of the present invention has a small amount of residual monomer, and when paying attention to the content of styrene as its component, it is preferably less than 50 ppm, more preferably less than 20 ppm, and there is no particular lower limit, but preferably 2 ppm. That's it.

The production method of the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Parts and% are based on weight unless otherwise specified.
The test methods performed in this example are as follows.

(Particle size of colored polymer particles)
The particle size distribution represented by the volume average particle diameter Dv of the colored polymer particles and the ratio Dv / Dp of the volume average particle diameter Dv and the number average particle diameter Dp is determined by a particle size measuring machine (manufactured by Beckman Coulter, product Name: Multisizer). Measurement conditions were as follows: aperture diameter = 100 μm, medium = Isoton II, concentration = 10%, number of measured particles = 100,000.

(Measurement of shell layer thickness of core-shell type colored polymer particles)
The core particles were collected and the average particle diameter was determined in the same manner as described above, and calculated from the amount of the polymerizable monomer for the shell used.

(Sphericality of colored polymer particles)
An electron micrograph of each particle of the colored polymer particles was taken, and the photograph was analyzed by an image analyzer (product name: Luzex IID) and determined. The conditions of the photograph were such that the area ratio of particles to the frame area was 2% or less and the number of particles measured was 100. A value obtained by dividing the area of the maximum outer circumference circle by the substantial cross-sectional area was measured for each particle, and the average value was defined as the sphericity Sc / Sr.

(Measurement of residual ether content and residual styrene content in polymerized toner)
Weigh accurately 3 g of polymerized toner to the nearest 1 mg. After adding 27 g of ethyl acetate to 3 g of the polymerized toner and stirring for 15 minutes, 13 g of methanol is added and stirred for another 10 minutes. The solution thus obtained is allowed to stand to precipitate insolubles. The supernatant of this solution is taken as a measurement sample, and 2 μl is injected into a gas chromatograph to quantify styrene and ether components. The measurement conditions by the gas chromatograph are as follows.
Column = Product name: DB-5, manufactured by Agilent, 0.25 mm × 30 m,
After maintaining the column temperature = 40 ° C. for 3 minutes, the temperature is raised to 130 ° C. at 10 ° C./min. After reaching 130 ° C., the temperature is raised to 230 ° C. at 20 ° C./min.
Injection temperature = 200 ° C
FID detection temperature = 250 ° C
Standard sample for quantification: The same ethyl acetate / methanol solution as above for each component to be detected

(High temperature storage stability test)
20 g of the polymerized toner was put in a container and sealed, and then the container was submerged in a constant temperature water bath at a temperature of 60 ° C. and taken out after 5 hours. The toner was transferred from the taken-out container onto a 42-mesh sieve so as not to vibrate as much as possible, and set in a powder measuring machine (product name PowderTester manufactured by Hosokawa Micron Corporation). After setting the amplitude of the sieve to 1.0 mm and vibrating for 30 seconds, the weight of the toner remaining on the sieve was measured, and this was defined as the weight of the aggregated toner. The high-temperature storage stability (%) of the toner was calculated from the ratio (% by weight) of the weight of the toner remaining on the sieve (corresponding to the weight of the agglomerated toner) to the measured toner weight (20 g). The high temperature storage stability (%) of the toner indicates that the smaller the numerical value, the less the aggregated toner and the better the high temperature storage stability.

(Print durability test) (Number of NN environmental fog occurrences, number of HH environmental fog occurrences)
Put polymerized toner in a commercially available non-magnetic one-component development type printer (printing speed 18 sheets (A4 paper) / min) and leave it for a whole day and night in an environment with a temperature of 23 ° C. and a humidity of 50% (NN environment). Under an NN environment, continuous printing was performed at a printing density of 1%, and printing was stopped once every 1,000 sheets, and fog was measured. The number of sheets in which the following fogging ΔE was 1 or more was defined as the number of NN environment fog generation (unit: K = 1,000 sheets). First, fog is printed in white (printing an image that should not be printed), and the printer is stopped in the middle of printing, and the toner on the non-image area on the photoconductor after development is applied to the adhesive tape. (Product name: Scotch Mending Tape 810-3-18, manufactured by Sumitomo 3M Limited) was peeled off and affixed to new printing paper. The color tone was measured with a spectral color difference meter (Nippon Denshoku Co., Ltd., product name SE-2000) at the portion where the toner in the non-image area was adhered. Similarly, as a control, an unused adhesive tape is attached to the printing paper and used as a reference sample, and the color tone is measured in the same manner, and each color tone is expressed as coordinates in L * a * b * space. The color difference ΔE was calculated from the color tone of the sample and used as the fog value. Smaller fog values indicate less fog and better image quality.

  A similar printing durability test was performed in an environment (HH environment) at a temperature of 28 ° C. and a humidity of 80% to obtain the number of HH environment fog generation.

(Odor test)
For the odor test of the polymerized toner, 10 monitors were selected at random, and in the printing durability test (NN environmental fog), the odor of the printer exhaust part at the time of printing the 1,000th sheet was subjected to a sensory test.
Evaluation A. Nine or more out of 10 people did not mind the odor.
Evaluation B: 7 or more out of 10 people were worried about the odor, but felt that it was not unpleasant.
Evaluation C 5 or more out of 10 felt uncomfortable with the odor.

Example 1
Polymerizable monomer for core consisting of 75 parts of styrene and 25 parts of n-butyl acrylate,
0.25 parts of a polymethacrylic acid ester macromonomer (manufactured by Toa Gosei Chemical Co., Ltd., product name AA6) as a macromonomer,
1 part of copper phthalocyanine pigment (Dainippon Ink, product name CTBX121),
And 1 part of a charge control agent (styrene / acrylic resin, manufactured by Fujikura Kasei Co., Ltd., product name FCA-207P),
After stirring and mixing with a stirrer having a normal stirring blade, it was uniformly dispersed with a media-type disperser. here,
As a release agent, 5 parts of pentaerythritol tetramyristate was added, mixed and dissolved to obtain a polymerizable monomer composition for core.

Apart from this, at 25 ° C,
While stirring an aqueous solution obtained by dissolving 8.6 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water,
An aqueous solution in which 4.8 parts of sodium hydroxide (alkali metal hydroxide salt) is dissolved in 50 parts of ion-exchanged water,
Add gradually,
A dispersion of magnesium hydroxide colloid (a slightly water-soluble metal hydroxide colloid) was prepared. When the particle size distribution of the obtained colloid was measured with a particle size distribution measuring device (manufactured by Shimadzu Corporation, product name SALD tangible distribution measuring device), D50 (50% cumulative value from small particle size of number particle size distribution) was 0.36 μm and D90 (90% cumulative value) were 0.80 μm.

Add the above-mentioned core polymerizable monomer composition to the magnesium hydroxide colloid dispersion at 25 ° C. until the generated coarse droplets are stabilized by a stirrer equipped with a normal stirring blade. Stir. here,
4.5 parts of t-butylperoxy diethyl acetate as a polymerization initiator,
Add 1.0 parts of tetraethylthiuram disulfide (TETD) as a molecular weight modifier and 0.5 parts of divinylbenzene as a crosslinkable polymerizable monomer. Was used to granulate droplets of the polymerizable monomer composition by high-speed shearing stirring for 10 minutes at a rotational speed of 15,000 rpm.

Apart from this, at 25 ° C,
While stirring an aqueous solution obtained by dissolving 1.51 parts of magnesium chloride in 39.64 parts of ion-exchanged water,
An aqueous solution in which 0.92 parts of sodium hydroxide is dissolved in 7.93 parts of ion-exchanged water,
Add gradually,
A dispersion of colloidal magnesium hydroxide colloid was prepared.

Aside from this,
As a polymerizable monomer for the shell, 1 part of methyl methacrylate
As a water-soluble polymerization initiator for the shell, a solution was prepared by dissolving 0.1 part of product name VA086 manufactured by Wako Pure Chemical Industries, Ltd. in 10 parts of ion-exchanged water.

  A reactor equipped with a stirring device having a stirring blade was prepared. From the upper part of the reactor, the preliminarily charged magnesium hydroxide colloid dispersion was sprayed on the reactor wall and the stirrer through a sprayer. The preliminarily charged dispersion of colloidal magnesium hydroxide was collected at the bottom of the reactor.

  The aqueous dispersion in which the droplets of the above-described polymerizable monomer for core were dispersed was introduced into the reactor from above. At this time, the preliminarily charged dispersion of magnesium hydroxide colloid accumulated in the lower part of the reactor moderated the impact of the dropping of the aqueous dispersion in which the droplets of the polymerizable monomer for the core were dispersed.

  The liquid in the reactor was heated by a jacket provided outside the reactor, and the temperature of the liquid was increased to 90 ° C. to initiate the polymerization reaction of the core polymerizable monomer composition. When the polymerization reaction is continued and the polymerization conversion rate reaches 95%, the above-mentioned shell polymerizable monomer and the above-mentioned water-soluble polymerization start for the shell are maintained while maintaining the temperature in the system at 90 ° C. The agent was added. Further, the polymerization reaction is continued by maintaining the system temperature at 90 ° C. for 3 hours, and then the polymerization reaction is performed by lowering the system temperature to room temperature (about 25 ° C.) by circulating cooling water through the jacket. Stopped. By the above operation, an aqueous dispersion containing core-shell type colored polymer particles was obtained in the reactor. The pH of the internal solution in the reactor was 0.5.

The resulting aqueous dispersion containing the colored polymer particles was stripped using the apparatus shown in FIG. 1 as follows. First, ion-exchanged water was added to the aqueous dispersion containing the colored polymer particles and diluted so that the solid content concentration was 20%. The aqueous dispersion containing the colored polymer particles after dilution was supplied to the evaporator 1. 0.1 part of a non-silicone antifoaming agent (manufactured by San Nopco, product name SN deformer 180) was added thereto. Nitrogen gas was allowed to flow into the evaporator 1 and the gas layer was replaced with nitrogen gas. Next, the water-based dispersion containing the colored polymer particles is stirred at 20 rpm with the stirring blade 2 and warm water is passed through a jacket provided in contact with the outside of the evaporator 1 to heat the evaporator. The aqueous dispersion containing the colored polymer particles was heated to 80 ° C. Thereafter, the blower 5 is started, and nitrogen gas is blown into the liquid of the aqueous dispersion liquid containing the colored polymer particles from the gas blow pipe 3 having a straight pipe shape to remove volatile substances in the liquid. It began to. Such a stripping step was performed for 6 hours while adjusting the liquid temperature in the evaporator to 80 ° C., the pressure of 48 kPa, and the flow rate of nitrogen gas to 0.1 L / hr · kg. During this time, the foam level was maintained at 90% or more and 95% or less. Thereafter, the aqueous medium containing the colored polymer particles was cooled to 25 ° C. by passing cooling water through the jacket.

  While stirring the aqueous medium containing the colored polymer particles after cooling, acid washing was performed by adding sulfuric acid thereto and neutralizing the pH of the liquid to 4.5. The wet colored polymer particles were separated (filtered) from the aqueous dispersion containing the neutralized colored polymer particles by filtration. Thereafter, 500 parts of ion-exchanged water was newly added, and the colored polymer particles in a wet state were slurried again and again filtered. By repeating this slurrying and filtering five times, the wet colored polymer particles were washed with water. The wet colored polymer particles after washing with water are dried in a vacuum dryer at a temperature of 50 ° C. and a pressure of 4 kPa for 24 hours, and the dried colored polymer particles (in the present invention, sometimes simply referred to as colored polymer particles). .)

  The obtained colored polymer particles are core-shell colored polymer particles, the volume average particle size (Dv) is 9.5 μm, the particle size distribution (Dv / Dp) is 1.16, and the shell thickness is 0.03 μm. The sphericity Sc / Sr was 1.2.

  To 100 parts of colored polymer particles, 0.8 part of hydrophobized fine particles (product name: TG820F, manufactured by Capot Co., Ltd.) and 1 part of hydrophobized fine particles (product name: NA50Y, manufactured by Nippon Aerosil Co., Ltd.) are added. They were mixed using a mixer and externally added to obtain a non-magnetic one-component polymerized toner. The test results of the obtained toner are summarized in Table 1.

( Comparative Example 1 )
For the core, 5 parts of t-butylperoxy-2- ethylhexanoate is used in place of t-butylperoxydiethyl acetate as a polymerization initiator, and t-dodecyl mercaptan is used in place of TETD as a molecular weight modifier in 1.2 parts. During the stripping process, the liquid temperature in the evaporator is raised from 80 ° C. to 85 ° C., the pressure in the evaporator is raised from 48 kPa to 60 kPa to reduce the degree of vacuum, and the stripping treatment time is reduced to 10 hours. A polymerized toner was obtained in the same manner as in Example 1 except for the extension. Table 1 summarizes the stripping process conditions, results, and test results of the polymerized toner.

(Comparative Example 2 )
The core molecular weight modifier TETD is reduced to 0.5 parts, the crosslinkable polymerizable monomer divinylbenzene is reduced to 0.25 parts, and the pressure in the evaporator during the stripping process is reduced from 48 kPa. A polymerized toner was obtained in the same manner as in Example 1 except that the pressure was increased to 101 Pa to normal pressure, and the stripping treatment time was extended to 20 hours. Table 1 summarizes the stripping process conditions, results, and test results of the polymerized toner.

(Comparative Example 3 )
Use 5 parts of t-butylperoxy-2- ethylhexanoate instead of t-butylperoxydiethylacetate as a polymerization initiator for the core, reduce the molecular weight modifier TETD to 0.5 parts, The stripping process was attempted in the same manner as in Example 1 except that the polymerizable monomer divinylbenzene was reduced to 0.25 parts and no antifoam was used in the stripping process. During the process, the foaming in the evaporator 1 became intense, the foam level exceeded 100%, and further processing became difficult, so the stripping process was interrupted in 2 hours. Thereafter, in the same manner as in Example 1, acid washing, washing with water, filtration and drying were performed to obtain a polymerized toner. Table 1 summarizes the stripping process conditions, results, and test results of the polymerized toner.

(Comparative Example 4 )
Use 5 parts t-butylperoxy-2- ethylhexanoate instead of t-butylperoxydiethyl acetate as a polymerization initiator for the core, and 4 parts t-dodecyl mercaptan instead of TETD as a molecular weight regulator. Then, the crosslinkable polymerizable monomer divinylbenzene was increased to 3 parts, the liquid temperature in the evaporator was increased from 80 ° C. to 85 ° C. during the stripping step, and the pressure in the evaporator was increased from 48 kPa to 60 kPa. The polymerized toner was obtained in the same manner as in Example 1 except that the degree of decompression was increased and the stripping treatment time was extended to 10 hours. Table 1 summarizes the stripping process conditions, results, and test results of the polymerized toner.

From the test results described in Table 1, the following can be understood. When the stripping process is carried out at normal pressure without reducing pressure (Comparative Example 2 ), the residual ether of the resulting polymerized toner is not sufficiently lowered, and high-temperature storage stability, NN durability, and HH durability are improved. Inferior and odor is generated during development. When an antifoaming agent is not used (Comparative Example 3 ), stable operation cannot be performed during the stripping process. When the amount of residual ether in the polymerized toner is large (Comparative Example 4 ), the amount of residual styrene is also large, high temperature storage stability, NN durability, and HH property are inferior, and odor is generated during development. In Comparative Example 1, the amount of residual ether is 320 ppm. In contrast, in the embodiment 1, it is possible to perform the step of stripping stable and residual ether and residual styrene less, high-temperature storage stability, NN durability and HH durability superior during development Odor is not generated.

  The polymerized toner of the present invention and the polymerized toner obtained by the production method of the present invention can be used as a developer in an electrophotographic image forming apparatus such as a facsimile, a copying machine, and a printer.

It is a figure which shows the example of the apparatus for the stripping process employ | adopted by the Example of this invention.

Explanation of symbols

1: Evaporator 2: Stirring blade 3: Gas blowing pipe 4: Trace gas blowing pipe 5: Blower 6: Gas circulation line 7: Condenser 8: Condensing tank 9: Gas circulation line 10: Volatile substance removing device 11: Gas Circulation line 12: Non-contact type foam level meter

Claims (7)

A polymerizable monomer composition containing a polymerizable monomer and a colorant is polymerized in an aqueous medium in the presence of an organic peroxide as a polymerization initiator, and an aqueous dispersion containing colored polymer particles is obtained. And polymerization obtained through a stripping step of injecting air or an inert gas under the surface of the aqueous dispersion while stirring in an evaporator having a gas phase pressure of 5 to 80 kPa. A toner, wherein the organic peroxide is represented by the following formula (1):
R—CO—O—O—R ′ (1)
[In the formula, R is an alkyl group having 6 or less carbon atoms, and R ′ is an alkyl group having 8 or less carbon atoms. ]
A non-aromatic peroxyester, wherein the polymer toner has an ether component content of less than 100 ppm. In the stripping treatment step, the aqueous medium is an oil-based antifoaming agent, a mineral oil-based antifoaming agent, a polyether-based antifoaming agent, a polyalkylene glycol type nonionic surfactant, and an oil and fat and a polyalkylene glycol type nonionic. The polymerized toner according to claim 1, comprising at least one non-silicone antifoaming agent selected from the group consisting of emulsions containing a surfactant. The molecular weight of the non-aromatic peroxy esters, polymerized toner according to claim 1 or 2 Ru der 205 or less. The polymerized toner according to any one of claims 1 to 3 styrene content, and less than 50 ppm. The polymerizable monomer composition contains 0.01 to 3 parts by weight of a molecular weight modifier with respect to 100 parts by weight of the monovinyl monomer in the polymerizable monomer. the polymerized toner according to any one of claims 1 to 4. The polymerizable monomer composition contains at least one compound selected from the group consisting of a mercaptan compound, a thiuram compound, and a dithiocarbamic acid compound as a molecular weight regulator. The polymerized toner according to any one of the above. In a method for producing a polymerized toner containing colored polymer particles obtained by polymerizing a polymerizable monomer composition containing a polymerizable monomer and a colorant in an aqueous medium in the presence of a polymerization initiator. , Using an organic peroxide as the polymerization initiator,
A stripping step of injecting a gas composed of air or an inert gas below the liquid surface while stirring the aqueous medium containing the colored polymer particles in an evaporator having a gas phase pressure of 5 to 80 kPa. By doing
A method for producing a polymerized toner, wherein the content of the ether component in the polymerized toner is less than 100 ppm , wherein the organic peroxide is represented by the following formula (1):
R—CO—O—O—R ′ (1)
[In the formula, R is an alkyl group having 6 or less carbon atoms, and R ′ is an alkyl group having 8 or less carbon atoms. ]
A method for producing a polymerized toner which is a non-aromatic peroxyester .

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