JP5109240B2 - Method for producing polymerized toner - Google Patents

Description

  The present invention relates to a polymerized toner that can be used for developing an image forming apparatus using electrophotography such as a copying machine, a facsimile machine, and a printer.

  In printing using electrophotography, an electrostatic latent image formed on a photoreceptor is developed with toner to form a toner image, and the toner image is transferred onto a transfer material such as paper. The transferred toner image is heated and pressed by a hot-pressure roll and fixed on the transfer material.

  Conventionally, a toner by a pulverization method (pulverized toner) obtained by melt-kneading a binder resin obtained by polymerizing a polymerizable monomer, a colorant and the like, and then pulverizing and classifying the toner is generally used. Has been. However, in the pulverization method, particularly when a toner having a small particle diameter is produced, there are problems such as a decrease in yield and consumption of a large amount of energy for pulverization. ) Has been proposed.

Examples of the method for producing the polymerized toner include a suspension polymerization method and an emulsion aggregation method.
For example, in the suspension polymerization method, first, a polymerizable monomer, and additives such as a colorant, a charge control agent, and a molecular weight modifier as necessary are mixed to obtain a polymerizable monomer composition. It is dispersed in an aqueous medium having a dispersion stabilizer. Next, the aqueous medium in which the polymerizable monomer composition is dispersed is applied with a high share using a high-speed stirrer or the like to form droplets of the polymerizable monomer composition, and then in the presence of the polymerization initiator. Then, after filtration, washing and drying, dried colored polymer particles are obtained. Furthermore, the colored polymer particles are mixed with an external additive such as a carrier and / or inorganic fine particles to obtain a polymerized toner.

  However, some of the above additives inhibit polymerization, and unreacted polymerizable monomers remain in the colored polymer particles. Further, in addition to the polymerizable monomer, a compound or molecular weight modifier that is by-produced by the polymerization initiator may remain.

  Polymer toners in which these toners remain tend to be low in storage stability of the toner, and when this toner is used for printing, residual low molecular weight components are volatilized by heating during fixing, resulting in toxic volatile components and bad odors. Occurs and worsens the surrounding environment. Furthermore, there is a problem that when durability printing is performed, particularly when durability printing is performed under high temperature and high humidity conditions, the durability is likely to deteriorate.

  In order to remove the polymerizable monomer remaining in the toner after polymerization in response to the above problems, a toner that is dried after treating the dispersion containing colored polymer particles after suspension polymerization by a vacuum stripping method. A toner using t-butylperoxy-2-ethylhexanoate (molecular weight 216) as a polymerization initiator is disclosed (Patent Document 1). In addition, as a method for removing the polymerizable monomer remaining in the toner after polymerization, a production method in which a vacuum stripping process is performed under a specific stirring condition has been proposed, and t-butyl peroxyisobutyrate (Nippon Oils and Fats) is proposed. A toner using a trade name “Perbutyl IB”, a molecular weight of 160, and a purity of 74%, manufactured by the same company as a polymerization initiator is disclosed (Patent Document 2).

However, in these toners, the amount of the unreacted polymerizable monomer is reduced and the amount of the polymerizable monomer remaining in the toner is reduced. In the toner obtained, the durability of printing, particularly the durability of printing under high temperature and high humidity, was not sufficient.
In addition, if excessive treatment is performed to further remove residual low molecular weight components, the colored polymer particles may be aggregated during the treatment, or the printing durability of the resulting toner may be easily reduced, and there is a limit. there were.

As a method for reducing the degradation amount of the polymerization initiator remaining in the toner after polymerization and the amount of residual monomer (polymerizable monomer), as a polymerization initiator, dicinnamoyl peroxide and carbon number 4 which are aromatic peroxides are used. A method for producing a resin for toner using at least one selected from the group consisting of 8 to 8 tertiary alkyl peroxycinnamates (the molecular weight of which is the smallest among these is 220) has been proposed (Patent Literature). 3). When a polymerization initiator by this method is used, a large amount of the polymerizable monomer remaining in the obtained toner and a large amount of a compound by-produced by the polymerization initiator remain. The durability of printing under humidity was not sufficient.
JP2000-321809 JP 2001-117272 A JP2000-3076

  An object of the present invention is excellent in storage stability of toner, does not generate bad odor when printing, does not deteriorate the surrounding environment, and has excellent durability when performing durable printing under high temperature and high humidity. It is to provide a method for producing a polymerized toner.

  As a result of extensive studies on the properties of the polymerization initiator used in the production of the polymerized toner, the present inventors have found that the polymerization initiator has a molecular weight of 205 or less and a purity of 90% or more with less impurities and diluents. It has been found that the above-mentioned problems can be solved by producing a polymerized toner using an organic peroxide.

That is, according to the present invention, a colored polymer obtained by polymerizing a polymerizable monomer composition containing a polymerizable monomer and a colorant in the presence of a polymerization initiator in an aqueous dispersion medium. A method for producing a toner containing particles, wherein the polymerization initiator is an organic peroxide, the molecular weight of the organic peroxide is 170 or more and 205 or less, and the purity of the organic peroxide is 90% or more. And the organic peroxide is represented by the following formula (1):

(In formula (1), R ′ represents an arbitrary alkyl group.) R in the formula (1) is a secondary alkyl group having 5 or less carbon atoms. A method for producing a polymerized toner is provided.

Moreover, it is preferable that the 1-hour half life temperature of this organic peroxide is 70 degreeC or more and 95 degrees C or less.

  According to the present invention, there is provided a polymerized toner which has excellent storage stability of the toner, does not cause bad odor when printing and does not deteriorate the surrounding environment, and has excellent durability when performing durable printing under high temperature and high humidity. Provided.

Hereinafter, a method for producing the polymerized toner of the present invention will be described.
The polymerized toner of the present invention is produced as follows. First, a polymerizable monomer, a colorant, and other additives such as a charge control agent as necessary are mixed to obtain a polymerizable monomer composition. This polymerizable monomer composition is placed in an aqueous medium, and an organic peroxide having a molecular weight of 205 or less and a purity of 90% or more is added thereto as a polymerization initiator to form droplets, followed by polymerization. And an aqueous dispersion of colored polymer particles is obtained. This aqueous dispersion is washed, dehydrated and dried, classified as necessary, and further added with external additives or / and carriers as necessary to obtain a polymerized toner.

(1) Polymerizable monomer composition 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 And nitrile compounds such as methacrylonitrile; amide compounds such as acrylamide and methacrylamide; olefins such as ethylene, propylene, and butylene; vinyl chloride, vinylidene chloride, and Vinyl halides and vinylidene 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 so that the glass transition temperature (hereinafter referred to as Tg) of the polymer obtained by polymerizing the monovinyl monomer is 80 ° C. or lower. By using monovinyl monomers alone or in combination of two or more, the Tg of the polymer can be adjusted to a desired range.

In order to improve hot offset, it is preferable to use any crosslinkable polymerizable monomer together with the monovinyl monomer. A crosslinkable polymerizable monomer means a 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; alcohols having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; Examples include ester compounds in which two or more carboxylic acids are ester-bonded; other divinyl compounds such as N, N-divinylaniline and divinyl ether; compounds having three or more vinyl groups. These crosslinkable polymerizable monomers can be used alone or in combination of two or more.
In the present invention, the crosslinkable polymerizable monomer is usually used at a ratio of 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, with respect to 100 parts by weight of the monovinyl monomer. desirable.

  Furthermore, it is preferable to use a macromonomer as a part of the polymerizable monomer because the balance between the storage stability of the obtained toner and the fixing property at low temperature 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 one that gives a polymer having a higher Tg than the Tg of the polymer obtained by polymerizing a monovinyl monomer. The macromonomer is preferably used in an amount of 0.03 to 5 parts by weight, more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the monovinyl monomer.

In the present invention, a colorant is used. However, when producing a color toner, black, cyan, yellow, and magenta colorants can be used.
As the black colorant, carbon black, titanium black, magnetic powder such as iron zinc oxide and nickel iron oxide 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: 1, 60, and the like.

  Examples of the yellow colorant include monoazo pigments, azo pigments such as disazo pigments, and compounds such as condensed polycyclic pigments. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 155, 180, 181, 185, and 186.

  As the magenta colorant, monoazo pigments, azo pigments such as disazo pigments, and compounds such as condensed polycyclic pigments are used. 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. I. Pigment Violet 19 etc. are mentioned.

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

As other additives, a charge control agent can be used, and various positively or negatively chargeable charge control agents are used. Non-resin charge control agents such as metal complexes of organic compounds having carboxyl groups or nitrogen-containing groups, metal-containing dyes, and nigrosine; quaternary ammonium groups or quaternary ammonium base-containing copolymers, sulfonic acid groups or sulfonate group-containing A charge control resin such as a copolymer and a carboxylic acid or a carboxylate group-containing copolymer can be used. The charge control agent preferably contains a charge control resin because the printing durability of the toner becomes good. Of the charge control agents, a charge control agent that is not a resin and a charge control resin may be used in combination, or the charge control resin may be used alone. More preferably, the charge control resin is used alone. It is more preferable to use a quaternary ammonium group or quaternary ammonium base-containing copolymer, or a sulfonic acid group or sulfonate group-containing copolymer as the charge control resin.
The charge control agent is usually used in a proportion of 0.01 to 10 parts by weight, preferably 0.03 to 8 parts by weight, with respect to 100 parts by weight of the monovinyl monomer.

  It is preferable to use a molecular weight modifier as another additive. Examples of molecular weight modifiers 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.

  The amount of the molecular weight modifier added is 0.05 to 10 parts, preferably 0.1 to 5 parts, more preferably 0.2 to 100 parts by weight with respect to 100 parts by weight of the monovinyl monomer. 3 parts. The molecular weight modifier is added before the polymerization starts or during the polymerization.

Further, as other additives, it is preferable to add a release agent since the releasability of the toner from the fixing roll during fixing can be improved.
Any releasing agent can be used without particular limitation as long as it is generally used as a releasing agent for toner. For example, low molecular weight polyolefin wax and modified wax thereof; plant natural wax such as jojoba; petroleum wax such as paraffin; mineral wax such as ozokerite; synthetic wax such as Fischer-Tropsch wax; polyhydric alcohol such as dipentaerythritol ester Ester; etc. are mentioned, and a polyhydric alcohol ester is preferable since the storage stability of the toner and the low-temperature fixability can be balanced. These may be used alone or in combination of two or more.
The release agent is preferably used in an amount of 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the monovinyl monomer.

(2) Polymerization initiator In the present invention, the polymerizable monomer composition obtained as described above is dispersed in an aqueous medium containing a dispersion stabilizer, and after adding a polymerization initiator, the polymerization property is increased. The droplet formation of the monomer composition is performed. The method for forming droplets is not particularly limited. For example, an (in-line type) emulsifying disperser (trade name “Milder” manufactured by Ebara Manufacturing Co., Ltd.), a high-speed emulsifying disperser (trade name “T. K. homomixer MARK type II)) or the like capable of strong stirring.

  In the present invention, an organic peroxide having a molecular weight of 205 or less and a purity of 90% or more is used as the polymerization initiator. By using a polymerization initiator that satisfies this specific condition, an unreacted polymerizable monomer remaining in the resulting toner, a compound by-produced by the polymerization initiator, a diluent contained in the polymerization initiator, and other It is thought that impurities are reduced. As a result, the toner of the present invention is excellent in the storage stability of the toner, does not cause bad odor when printing and does not deteriorate the surrounding environment, and durability when performing durable printing under high temperature and high humidity. A polymerized toner having excellent properties can be obtained.

  Polymerization using an organic peroxide is, for example, in the case of a peroxy ester, when the peroxy ester undergoes thermal decomposition, it is first decomposed into the corresponding alcohol radical and carboxylic acid radical, and then these radicals and carboxylic acid radicals. A polymerization reaction proceeds by adding an alkyl radical or the like generated by decarboxylation of the monomer to the monomer. However, various by-product compounds may be generated from these radicals by recombination or hydrogen abstraction.

  In addition, the organic peroxide having a low purity includes other compounds such as an organic peroxide and a diluent, which are different from the main organic peroxide, as impurities. Among organic peroxides, in particular, organic peroxides that have a high risk of ignition due to impact or heating need to add a diluent. Impurity organic peroxide is different from the main component organic peroxide in suitable reaction conditions, so that the initiator efficiency is lowered, and the presence of other compounds such as a diluent causes unreacted toner. The residual amount of impurities such as polymerizable monomers, by-product compounds and diluents tends to increase.

Among organic peroxides, peroxyesters are preferred because the initiator efficiency is good and the remaining polymerizable monomer can be reduced, and non-aromatic peroxyesters, that is, peroxyesters having no aromatic ring. Esters are more preferred.
Further, the organic peroxide is represented by the following formula (1)
(In the formula, R and R ′ each represents an arbitrary alkyl group) are more preferable. 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 the formula, 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, Examples thereof include t-butyl peroxy-2-methylbutanoate.

In the present invention, the molecular weight of the main component organic peroxide is 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 oxide represents the weight percentage of the organic peroxide as the main component with respect to the organic peroxide, 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 toner having good printing durability can be obtained. 85 degreeC or more and 95 degrees C or less are still 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.

  As described above, the polymerization initiator may be added after the polymerizable monomer composition is dispersed in the aqueous medium and before the droplet formation, but the polymerization before being dispersed in the aqueous medium. May be added to the functional monomer composition.

  The addition amount of the polymerization initiator used for polymerization of the polymerizable monomer composition is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 100 parts by weight of the monovinyl monomer. -15 parts by weight, most preferably 1-10 parts by weight.

  In the present invention, the aqueous medium refers to a medium containing water as a main component.

  In the present invention, the aqueous medium preferably contains a dispersion stabilizer. Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metals such as aluminum oxide and titanium oxide. Oxides; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; inorganic compounds such as; water-soluble polymers such as polyvinyl alcohol, methylcellulose, and gelatin; anionic surfactants; Organic compounds such as nonionic surfactants; amphoteric surfactants; The said dispersion stabilizer can be used 1 type or in combination of 2 or more types.

  The particle size distribution of the colored polymer particles can be narrowed, and the residual amount of the dispersion stabilizer after washing is small, so that the obtained polymerized toner can reproduce the image clearly and does not deteriorate the environmental stability. Therefore, among the above dispersion stabilizers, inorganic compounds, particularly colloids of poorly water-soluble metal hydroxides are preferable.

(4) Colored polymer particles As described above, droplets are formed, and the resulting aqueous dispersion medium is heated and polymerized in the presence of a polymerization initiator to form colored polymer particles.
The polymerization temperature of the polymerizable monomer composition is preferably 50 ° C. or higher, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

  The colored polymer particles may be used as polymerized toners as they are or with the addition of an external additive. However, the colored polymer particles are obtained by using the colored polymer particles as a core layer and forming a shell layer different from the core layer on the outside. The so-called core-shell type (or “capsule type”) colored polymer particles are preferable. 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.

  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 a conventionally well-known method. An in situ polymerization method and a phase separation method are preferable from the viewpoint of production efficiency.

A method for producing core-shell type colored polymer particles by in situ polymerization will be described below.
In the aqueous medium in which the colored polymer particles are dispersed, a polymerizable monomer (shell polymerizable monomer) for forming a shell layer and a polymerization initiator are added and polymerized to form a core-shell type. Colored polymer particles can be obtained.

  As the polymerizable monomer for the shell, the same monomers as the aforementioned polymerizable monomers can be used. Among them, it is preferable to use monomers such as styrene, acrylonitrile, and methyl methacrylate, which can obtain a polymer having a Tg exceeding 80 ° C., alone or in combination of two or more.

  As a polymerization initiator used for polymerization of the polymerizable monomer for shell, persulfate metal salts such as potassium persulfate and ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) Water-soluble such as azo initiators such as) propionamide) and 2,2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); A polymerization initiator can be mentioned. The amount of the polymerization initiator 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 polymerizable monomer for shell.

  The polymerization temperature of the shell layer is preferably 50 ° C. or higher, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

  The aqueous dispersion of colored polymer particles obtained by polymerization is subjected to filtration, removal of the dispersion stabilizer, washing, dehydration, and drying several times as necessary after the completion of polymerization. Preferably it is repeated.

  As the above washing method, when an inorganic compound is used as the dispersion stabilizer, the dispersion stabilizer is dissolved in water and removed by adding an acid or alkali to the aqueous dispersion of colored polymer particles. Is preferred. When a colloid of a poorly water-soluble inorganic hydroxide is used as the dispersion stabilizer, it is preferable to adjust the pH of the colored polymer particle aqueous dispersion to 6.5 or less by adding an acid. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid and acetic acid can be used. Particularly, since the removal efficiency is large and the burden on the manufacturing equipment is small, Sulfuric acid is preferred.

  Various known methods can be used for the method of dehydration and filtration, and are not particularly limited. For example, a centrifugal filtration method, a vacuum filtration method, a pressure filtration method, and the like can be given. Also, the drying method is not particularly limited, and various methods can be used.

  The colored polymer particles or the core-shell type colored polymer particles constituting the polymer toner obtained by the production method of the present invention will be described (the following colored polymer particles include both the core-shell type and those not) .

  The volume average particle diameter Dv of the colored polymer particles is preferably 3 to 15 μm, more preferably 4 to 12 μm. If Dv is less than these ranges, the fluidity of the polymerized toner may decrease, transferability may deteriorate, blurring may occur, and print density may decrease. If these ranges are exceeded, the resolution of the image may be reduced. May decrease.

  The colored polymer particles preferably have a ratio Dv / Dp of the volume average particle diameter Dv to the number average particle diameter Dp of 1.0 to 1.3, more preferably 1.0 to 1.2. It is. When Dv / Dp exceeds these ranges, blurring may occur, and transferability, image density, and resolution may decrease. The volume average particle diameter and the number average particle diameter of the colored polymer particles can be measured using, for example, a particle size analyzer (trade name “Multisizer” manufactured by Beckman Coulter).

Furthermore, it is preferable to use the colored polymer particles having a sphericity Sc / Sr of 1.0 to 1.3, and a sphericity Sc / Sr of 1.0 to 1.2. More preferably, it is used. If the sphericity Sc / Sr exceeds these ranges, the transferability may be reduced, or the fluidity of the toner may be reduced, and the toner may be easily lost. The sphericity Sc / Sr of the colored polymer particles is determined as follows. Colored polymer particles are photographed with an electron microscope, and the resulting photograph is taken up by an image processing analyzer (trade name: Luzex IID, manufactured by Nireco) with a particle area ratio of up to 2% and a total number of treatments of 100. Measure under the following conditions. It is obtained by averaging the sphericity Sc / Sr of the 100 colored polymer particles obtained.
Sphericality = Sc / Sr
Sc: area of a circle having the absolute maximum length of the colored polymer particles as a diameter Sr: substantial projected area of the colored polymer particles

(5) Polymerized toner The polymerized toner obtained by the production method of the present invention can be used as it is in the development of electrophotography with the colored polymer particles as they are. Further, using a high-speed stirrer such as a Henschel mixer, the colored polymer particles, the external additive, and other particles as required can be mixed to obtain a one-component polymerized toner. In addition to colored polymer particles, external additives, and other particles as required, carrier particles such as ferrite and iron powder are further mixed by various known methods to produce a two-component polymer toner. It can also be. When the technique of the present invention is applied, the effect of the present invention is more exerted, so that it is preferably a non-magnetic polymerized toner, and more preferably a non-magnetic one-component polymer toner.

Examples of the external additive include inorganic particles and organic resin particles that are usually used for the purpose of improving fluidity and chargeability. Examples of inorganic particles include silica, aluminum oxide, titanium oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, and cerium oxide. Examples of organic resin particles include methacrylic acid ester polymers and acrylic acid esters. Examples thereof include a polymer, a styrene-methacrylic acid ester copolymer, a styrene-acrylic acid ester copolymer, a melamine resin, and a core-shell type particle in which a core is a styrene polymer and a shell is a methacrylic acid ester polymer. Of these, silica and titanium oxide are preferable, and particles having a hydrophobic surface are preferable, and silica having a hydrophobic surface is more preferable. It is more preferable to use two or more types of hydrophobized silica in combination.
Although the addition amount of an external additive is not specifically limited, Usually, it is 0.1-6 weight part with respect to 100 weight part of colored polymer particles.

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.

(1) Particle size Volume average particle size Dv, particle size distribution, that is, ratio Dv / Dp of volume average particle size to number average particle size Dp, and number% of colored particles having a particle size of 4 μm or less are a particle size measuring machine ( Beckman Coulter, product name: Multisizer). The measurement with this multisizer was performed under the conditions of an aperture diameter: 100 μm, a medium: Isoton II, and a number of measured particles: 100,000.

(2) Average circularity of toner Into a container, 10 ml of ion-exchanged water is put in advance, 0.02 g of a surfactant (alkylbenzenesulfonic acid) as a dispersant is added, and 0.02 g of colored polymer particles is further added. In addition, the dispersion treatment was performed at 60 W for 3 minutes with an ultrasonic disperser. The concentration of the colored polymer particles at the time of measurement was adjusted to 3,000 to 10,000 particles / μL, and 1,000 to 10,000 colored polymer particles having an equivalent circle diameter of 1 μm or more were flow-type particle images. It measured using the analyzer (The Sysmex company make, product name: FPIA-2100). The average circularity was determined from the measured value. The circularity is expressed by the following formula, and the average circularity is an average of the circularity.
(Circularity) = (Perimeter of circle equal to projected area of particle) / (Perimeter of particle projection image)

(3) Storage stability evaluation After 20 g of toner was put in a container and sealed, the container was submerged in a constant temperature water bath at 55 ° C., and taken out after 8 hours. From the container, the toner was transferred onto a 42 mesh sieve so as not to be vibrated as much as possible, and set in a powder measuring machine (model name: PowderTester manufactured by Hosokawa Micron). The amplitude of the sieve was set to 1.0 mm, and after vibrating for 30 seconds, the weight of the toner remaining on the sieve was measured, and this was used as the weight of the aggregated toner. From the ratio of the weight of the aggregated toner to the measured toner weight, the storage stability (% by weight) of the toner was calculated. The toner storage stability (% by weight) indicates that the smaller the value, the less the aggregated toner and the better the storage stability.
Evaluation A: Less than 1% Evaluation B: 1% or more and less than 5% Evaluation C: 5% or more

(4) Odor Evaluation For the odor evaluation of the polymerized toner, 10 monitors were selected at random, and the odor of the exhaust part of the printer when printing 1,000 sheets was evaluated in the following printing durability test (NN environmental fog).
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.

(5) Printing durability test (number of NN environmental fog occurrences, number of HH environmental fog occurrences)
Put the toner in a commercially available non-magnetic one-component development type printer (printing speed 18 sheets (A4 paper) / min) and leave it in the environment of temperature 23 ° C and humidity 50% (NN environment) all day and night. Under the environment, continuous printing was performed at a printing density of 5%, and fogging was measured every 1,000 sheets. The number of sheets with fog of 1% or more was defined as the number of NN environment fog generation. Printing durability was performed up to 13,000 sheets. If fogging occurred on the way, printing durability was stopped at that time.
In the test results,> 13,000 sheets indicates that the above-mentioned standard is satisfied even if printing is performed continuously for 13,000 sheets.
The fog was measured as follows.
First, white solid printing is performed, and the printer is stopped halfway, and the toner in the non-image area on the developed photoreceptor is treated with adhesive tape (manufactured by Sumitomo 3M, trade name: Scotch Mending Tape 810-3- It was peeled off at 18) and pasted on a new printing paper. The color tone was measured with a spectral color difference meter (Nippon Denshoku Co., Ltd., device name: SE-2000) for the portion where the toner in the non-image area was adhered. Similarly, as a reference, an unused adhesive tape is affixed to the printing paper, the color tone is measured in the same manner, and each color tone is expressed as coordinates in the L * a * b * space. The fog value was obtained by calculating the color difference ΔE. 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.

Example 1
Polymerizable monomer comprising 75 parts of styrene and 25 parts of n-butyl acrylate (calculation of the resulting copolymer Tg = 60 ° C.), 5 parts of copper phthalocyanine as a colorant, charge control agent (styrene / acrylic resin, Fujikura) 1 part by Kasei Co., Ltd., trade name “FCA-207P”), 0.5 part of divinylbenzene as a crosslinkable polymerizable monomer, 1 part of t-dodecyl mercaptan as a molecular weight regulator, polymethacrylate macromonomer ( Toa Gosei Chemical Co., Ltd., trade name “AA6”, Tg = 94 ° C.) 0.25 part was stirred with a stirrer and then uniformly dispersed with a media-type disperser. Here, 5 parts of dipentaerythritol hexamyristate (solubility is 10 g / 100 g styrene, endothermic peak is 65 ° C., molecular weight is 1514) as a release agent is added, mixed and dissolved to form a polymerizable monomer composition I got a thing. All the preparations of the polymerizable monomer composition were performed at room temperature.
On the other hand, at room temperature, in an aqueous solution obtained by dissolving 8.6 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water, 4.8 parts of sodium hydroxide (alkali hydroxide) in 50 parts of ion-exchanged water. An aqueous solution in which was dissolved was gradually added with stirring to prepare a magnesium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion. All of the dispersions were prepared at room temperature. When the particle size distribution of the colloid was measured with a particle size distribution measuring instrument (Shimadzu Corporation, trade name: SALD), the particle size was D50 (50% cumulative value of the number particle size distribution) of 0.36 μm and D90 ( 90% cumulative value of the number particle size distribution) was 0.80 μm.

  The polymerizable monomer composition is charged into the magnesium hydroxide colloidal dispersion obtained as described above and stirred, and t-butylperoxy-2-ethylbutanoate (formula (1) is used as a polymerization initiator. ), R is 1-ethylpropyl, R ′ is t-butyl peroxyester, manufactured by Akzo Nobel, trade name “Torigonox27”, purity 98%, molecular weight 188, 1 hour half-life temperature 94 ° C., 10 hours half After adding 4.4 parts of an initial temperature of 75 ° C., a product name: TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) is used for high shear stirring at a rotational speed of 12,000 rpm to obtain a polymerizable monomer composition. Droplets were formed.

  Next, an aqueous dispersion of the polymerizable monomer composition formed into droplets was added from the top of the reactor. The temperature was raised to 90 ° C. to carry out the polymerization reaction. As a water-soluble initiator dissolved in 1 part of methyl methacrylate and 10 parts of ion-exchanged water as a polymerizable monomer for the shell while maintaining the temperature in the reactor at 90 ° C. when the polymerization addition rate reaches 95% 0.1 part of 2,2'-azobis (2-methyl-N- (2-hydroxyethyl) -propionamide) was added. The temperature was further maintained at 90 ° C. for 3 hours, and the polymerization was continued. Then, the reaction was stopped by cooling with water to obtain a slurry of colored polymer particles.

  The slurry is acid-washed with sulfuric acid to 6.5 or less with stirring, and water is separated by filtration. Then, 500 parts of ion-exchanged water is newly added to make a slurry again and washed with water. It was. Thereafter, dehydration and water washing were repeated again several times at room temperature, and the solid content was separated by filtration, then placed in a vacuum dryer container and vacuum dried at a pressure of 30 torr and a temperature of 50 ° C. overnight for 72 hours.

  The obtained colored polymer particles had a volume average particle diameter Dv of 9.5 μm and a volume average particle diameter / number average particle diameter Dv / Dp of 1.16. The obtained colored polymer particles had a shell thickness of 0.03 μm, an average circularity of 0.98, and a glass transition temperature of 63 ° C. as measured by DSC, calculated from the amount of shell monomer and the core particle size. It was.

To 100 parts of the colored polymer particles obtained as described above, 0.8 part of hydrophobized silica fine particles (average primary particle size: 7 nm) and hydrophobized silica fine particles (BET specific surface area of 50 m ² / g) 1 0.0 part was added and mixed using a Henschel mixer to prepare a non-magnetic one-component polymerized toner.
The obtained evaluation results are shown in Table 1.

(Reference Example 2)
The polymerization initiator was 5 parts of t-hexyl peroxypivalate (manufactured by NOF Corporation, trade name “Perhexyl PV”, purity 91%, molecular weight 202, 1 hour half-life temperature 71 ° C., 10 hour half-life temperature 53 ° C.) A polymerized toner was prepared in the same manner as in Example 1 except that. The test results are shown in Table 1.

(Comparative Example 1)
The polymerization initiator was t-hexylperoxypivalate (the polymerization initiator of Example 2 diluted with isoparaffin, purity 70%, molecular weight 202, 1 hour half-life temperature 71 ° C., 10 hour half-life temperature 53 ° C.) A polymerized toner was prepared in the same manner as in Example 1 except that the amount was 5.7 parts. The test results are shown in Table 1.

(Comparative Example 2)
Polymerization initiator was t-butylperoxy-2-ethylbutanoate (the polymerization initiator of Example 1 diluted with isoparaffin, purity 70%, molecular weight 188, 1 hour half-life temperature 94 ° C., 10 hour half-life) A polymerized toner was prepared in the same manner as in Example 1 except that the temperature was changed to 6.1 parts. The test results are shown in Table 1.

(Comparative Example 3)
The polymerization initiator was t-butyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name “Perbutyl O”, purity 98%, molecular weight 216, 1 hour half-life temperature 92 ° C., 10 hour half-life temperature 72 ° C. A polymerized toner was prepared in the same manner as in Example 1 except that 5 parts) were added. The test results are shown in Table 1.

1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name “Perocta O” purity 90%, molecular weight 272, 1 hour half-life temperature 84 ° C., A polymerized toner was prepared in the same manner as in Example 1 except that the 10-hour half-life temperature (65 ° C.) was 6.8 parts. The test results are shown in Table 1.

  The polymerized toner obtained by 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.

Claims (2)

Method for producing toner containing colored polymer particles obtained by polymerizing a polymerizable monomer composition containing a polymerizable monomer and a colorant in an aqueous dispersion medium in the presence of a polymerization initiator Because
The polymerization initiator is an organic peroxide;
The molecular weight of the organic peroxide is 170 or more and 205 or less, and the purity of the organic peroxide is 90% or more,
The organic peroxide is represented by the following formula (1)

(In formula (1), R ′ represents an arbitrary alkyl group.)
R in said Formula (1) is C5 or less and a secondary alkyl group, The manufacturing method of the polymerization toner characterized by the above-mentioned.   The method for producing a polymerized toner according to claim 1, wherein the organic peroxide has a one-hour half-life temperature of 70 ° C or higher and 95 ° C or lower.