JP2002365839A - Method for producing toner by polymerization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing toner by polymerization method by which the surfaces of toner particles can be efficiently and uniformly washed and a toner giving an image free of fog and having excellent image characteristics can be obtained. SOLUTION: The method for producing toner in which a toner synthesized in an aqueous medium is washed with a filtering means and dehydrated and the resulting wet colored resin particles are dried with a drying means to produce the objective toner is characterized in that the separation of the colored resin particles from the medium by filtration is carried out with a vacuum belt filter and the water content of the colored resin particles after the separation is <=35%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for producing a polymerization toner used in an image forming method for developing an electrostatic latent image and a toner jet recording method.

[0002]

2. Description of the Related Art Conventionally, many methods have been known as electrophotography. In general, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means. The latent image is developed with a toner to form a visible image, the toner image is transferred to a transfer material such as paper as necessary, and then the toner image is fixed on the transfer material by heat, pressure, etc. Is what you get.

Various methods have been conventionally proposed as a method of developing with toner or a method of fixing a toner image.

Conventionally, toners used for these purposes are:
Generally, a colorant comprising a dye or a pigment is melt-kneaded in a thermoplastic resin, uniformly dispersed, then finely pulverized by a fine pulverizer, and the finely pulverized material is classified by a classifier to obtain a desired particle size. Has been manufactured.

[0005] Although this method can produce fairly good toners, it does have certain limitations, namely the choice of toner materials. For example, the resin colorant dispersion must be sufficiently brittle and capable of being comminuted on economically feasible manufacturing equipment. However, when the resin colorant dispersion is made brittle to satisfy these requirements, when the dispersion is actually finely pulverized at a high speed, the particle size range of the formed particles tends to be widened, and particularly, the fine particles are formed in a relatively large proportion. Is included in this.

Further, the toner obtained from such a highly brittle material is susceptible to further pulverization or powdering in a developing device such as a copying machine. Further, in this method, it is difficult to completely and uniformly disperse solid fine particles such as a colorant in a resin, and depending on the degree of the dispersion, an increase in fog at the time of image formation, a decrease in image density, color mixing or transparency. Great care must be taken in dispersing the colorant, as this can lead to poor properties. Further, exposure of the coloring agent to the fracture surface of the pulverized particles may cause a change in development characteristics.

On the other hand, in order to overcome the problems of the toner caused by these pulverization methods, Japanese Patent Publication Nos.
Various polymerization toners and production methods thereof have been proposed, including suspension polymerization toners disclosed in JP-A-3-10799 and JP-A-51-14895. For example, in a suspension polymerization method toner, a polymerizable monomer, a colorant and a polymerization initiator, and further, if necessary, a crosslinking agent, a charge control agent, and other additives are uniformly dissolved or dispersed to prepare a monomer composition. After that, the monomer composition is dispersed in a medium containing a dispersion stabilizer, for example, an aqueous phase using a suitable stirrer, and simultaneously subjected to a polymerization reaction, and separated by filtration and dried to obtain a desired product. A toner particle having a particle size is obtained. In this method, since no pulverization step is included, the toner does not need to be brittle, a soft material can be used as the resin, and the colorant is not exposed on the particle surface, and uniform friction can be achieved. There is an advantage that a toner having chargeability can be obtained. Further, since the particle size distribution of the obtained toner is relatively sharp, even if the classification step is omitted or the classification is performed, the toner can be obtained in a high yield.

However, since the polymerized toner directly generates toner particles in the medium, the toner surface is easily affected by the medium.

For example, when the medium is an aqueous medium, a polar resin having a high polarity and a charge control agent generally tend to be localized near the toner surface. As a result, compared with the pulverized toner, a very small amount of the charge control agent can impart uniform and high chargeability to the toner, but a highly polar material such as the charge control agent is a very small part, Some are dissolved in an aqueous medium. Therefore, great care must be taken in the step of filtering the toner particles from the medium after the completion of the polymerization reaction.

That is, it is important how to efficiently and uniformly clean the surface of each toner particle. That is,
If the surface of each toner particle is not uniformly washed, the charge distribution of the toner becomes broad, and in an environment where the toner is difficult to be charged, such as under high temperature and high humidity, problems such as a decrease in image density and fog occur. Easier to do.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, to efficiently and uniformly clean the surface of each toner particle, and to form an image using the obtained toner. An object of the present invention is to provide a method for producing a polymerization toner capable of stably maintaining a high image density and obtaining a toner having excellent image characteristics without fogging or the like.

It is a further object of the present invention to provide a method for producing a polymerization toner capable of stably obtaining a high-quality image even in a high-temperature and high-humidity environment and obtaining a durable toner.

[0013]

The above object is achieved by the present invention described below.

That is, the present invention provides a method for producing a toner by washing a toner synthesized in an aqueous medium by a filtering means, dehydrating the toner, and drying the obtained wet colored resin particles by a drying means. In the production method, the colored resin particles are separated from the medium by filtration with a belt filter,
A polymerization method characterized in that the water content after filtration by the belt filter is 35% or less, and preferably, when vacuum filtration is performed with the belt filter, the filter cloth and the vacuum tray are in close contact with each other and do not rub. This is a method for producing a toner. Examples of the belt filter in which the filter cloth and the vacuum tray are in close contact with each other and do not rub against each other include a vacuum tray reciprocating type and an intermittent filter type belt filter.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.

The present inventors have conducted intensive studies to solve the above-mentioned problems of the prior art. As a result, in order to efficiently and uniformly clean the surface of each toner particle, the colored resin particles are separated from the medium by filtration. We found that the method had a significant effect.

Further, the present inventors have found that when separating solid particles from a slurry using a vacuum type belt filter, the surface of each toner particle can be efficiently and uniformly cleaned by setting the water content to 35% or less. The knowledge has led to the present invention.

The toner of the present invention contains at least a resin and a colorant, but may contain a releasing agent or a charge control agent as a fixability improving agent, if necessary.
Further, an external additive composed of inorganic fine particles, organic fine particles, and the like may be added to the toner particles containing the resin and the colorant as main components.

The toner of the present invention is obtained by subjecting a monomer to emulsion polymerization in a suspension polymerization method or a liquid to which an emulsion of necessary additives is added.
It can be produced by a method in which fine polymer particles are produced, and thereafter, an organic solvent, an aggregating agent and the like are added and associated.
A method of preparing by mixing and associating with a dispersion liquid such as a release agent or a colorant necessary for the composition of the toner at the time of association, or dispersing a toner component such as a release agent or a colorant in a monomer. And then emulsion polymerization. Here, “association” indicates that a plurality of resin particles and colorant particles are fused.

The "aqueous medium" in the present invention is defined as
It shows that at least 50% by mass of water is contained.

The production method of the polymerization method is not particularly limited, and examples thereof include the following production methods.

That is, a coloring agent and, if necessary, various constituent materials such as a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, an ultrasonic dispersion Various constituent materials are dissolved or dispersed in the polymerizable monomer by a machine or the like. The polymerizable monomer in which the various constituent materials are dissolved or dispersed is dispersed in an aqueous medium containing a dispersion stabilizer into oil droplets having a desired size as a toner by using a homomixer, a homogenizer, or the like. Thereafter, the mixture is transferred to a reaction device having a stirring mechanism and heated to cause the polymerization reaction to proceed. After completion of the reaction, the toner of the present invention is prepared by removing the dispersion stabilizer, filtering, washing and drying.

Further, as a method for producing the toner of the present invention, a method in which resin particles are fused and prepared in an aqueous medium can also be mentioned. Although this method is not particularly limited, for example, JP-A-5-265252, JP-A-6-329947, and JP-A-9-15
No. 904 can be mentioned. That is,
A method of associating a plurality of resin particles and dispersed particles of a constituent material such as a colorant, or a plurality of fine particles composed of a resin and a colorant, particularly, after dispersing these in an aqueous medium using an emulsifier, and then subjecting them to critical aggregation. At the same time as salting out by adding a coagulant having a concentration of not less than the glass transition temperature of the formed polymer itself, heat-fusing the particles, and heating and drying the particles in a fluid state in a water-containing state, of the present invention. A toner can be formed. Here, an organic solvent infinitely soluble in water may be added together with the coagulant.

The preferred monomers used in the present invention include, specifically, styrene-based monomers such as styrene, o (m-, p-)-methylstyrene and m (p-)-ethylstyrene; Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, (meth)
Dodecyl acrylate, stearyl (meth) acrylate,
Behenyl (meth) acrylate, 2- (meth) acrylate
(Meth) acrylate monomers such as ethylhexyl, dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile and acrylamide A dimer is preferably used. These can be used alone or generally in the published Polymer Handbook, 2nd edition III-P 139-192 (Jo).
hn Wiley & Sons) and the monomers are appropriately mixed and used so that the theoretical glass transition temperature (Tg) thereof is 40 to 75 ° C. Theoretical glass transition temperature is 40 ℃
If the temperature is less than 75 ° C., there arises a problem in terms of the storage stability of the toner and the durability stability of the developer. On the other hand, if the temperature exceeds 75 ° C., the fixation point is increased. And the color reproducibility is poor, and the transparency of the OHP image is remarkably reduced, which is not preferable from the viewpoint of high image quality.

The molecular weight of the outer shell resin is measured by GPC (gel permeation chromatography). As a specific GPC measurement method, the toner is extracted in advance with a toluene solvent using a Soxhlet extractor for 20 hours, and then the toluene is distilled off with a rotary evaporator. After washing sufficiently by adding an organic solvent that cannot be dissolved, such as chloroform, and the like, a solution dissolved in THF (tetrahydrofuran) was filtered through a solvent-resistant membrane filter having a pore diameter of 0.3 μm. And the column configuration was A-801, 802, 80 manufactured by Showa Denko
3, 804, 805, 806 and 807 can be connected to measure the molecular weight distribution using a standard polystyrene resin calibration curve.
The number average molecular weight (Mn) of the obtained resin component is 5000
An outer shell resin having a weight average molecular weight (Mw) and a number average molecular weight (Mn) of 2 to 100 is preferable for the present invention.

In the present invention, when a toner having a core / shell structure is produced, it is particularly preferable to further add a polar resin to the outer shell resin in order to incorporate a low softening point substance.

As the polar resin used in the present invention, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a saturated polyester resin, and an epoxy resin are preferably used. It is particularly preferable that the polar resin does not contain much unsaturated group in the molecule which can react with the outer shell resin or the monomer. If a polar resin having many unsaturated groups is contained, a cross-linking reaction occurs with the monomers forming the outer shell resin layer. Is disadvantageous and is not preferred.

In the present invention, an outermost shell resin layer may be further provided on the surface of the toner. The glass transition temperature of the outermost shell resin layer is preferably designed to be equal to or higher than the glass transition temperature of the outer shell resin layer in order to further improve blocking resistance, and it is preferable that the outermost shell resin layer is crosslinked so as not to impair fixability. . The outermost resin layer preferably contains a polar resin and a charge control agent for improving the chargeability.

The method for providing the outermost shell layer is not particularly limited, but includes, for example, the following methods.

1. The latter half of the polymerization reaction, or after the end, if necessary in the reaction system, dissolved polar resin, charge control agent, cross-linking agent, etc., added a monomer dispersed and adsorbed on the polymer particles,
A method in which polymerization is performed by adding a polymerization initiator. 2. If necessary, add emulsion polymerization particles or soap-free polymerization particles composed of monomers containing polar resin, charge control agent, cross-linking agent, etc. to the reaction system, agglomerate on the surface of the polymerization particles, fix if necessary according to the order, etc. How to let. 3. A method in which emulsion polymerized particles or soap-free polymerized particles comprising a monomer containing a polar resin, a charge control agent, a cross-linking agent, and the like, if necessary, are dry-mechanically fixed to the toner particle surfaces. It is.

As the colorant used in the present invention, a black colorant prepared by using carbon black, a magnetic substance, and the following yellow / magenta / cyan colorants as a black colorant is used.

Examples of the yellow colorant include condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
Compounds represented by azo metal complexes, methine compounds and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 6
2, 74, 83, 93, 94, 95, 109, 110,
111, 128, 129, 147, 168 and the like are preferably used.

Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, C.I.
I. Pigment Red 2,3,5,6,7,23,4
8: 2, 48: 3, 48: 4, 57: 1, 81: 1,1
22,144,146,166,169,177,18
4,185,202,206,220,221,254
Is particularly preferred.

As the cyan coloring agent used in the present invention, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds and the like can be used.
Specifically, C.I. I. Pigment Blue 1, 7, 15,
15: 1, 15: 2, 15: 3, 15: 4, 60, 6
2, 66 and the like can be particularly preferably used. These colorants can be used alone or as a mixture or in the form of a solid solution.

In the case of a color toner, the colorant used in the present invention is selected from the viewpoints of hue angle, saturation, lightness, weather resistance, OHP transparency, and dispersibility in the toner. The colorant is used in an amount of 1 to 20 parts by mass per 100 parts by mass of the resin.

When a magnetic material is used as the black colorant, unlike other colorants, 4 to 1 with respect to 100 parts by mass of the resin.
Used by adding 50 parts by mass.

The charge control agents used in the present invention include:
Although a known toner can be used, in the case of a color toner, a charge control agent which is colorless, has a high toner charging speed, and can stably maintain a constant charge amount is particularly preferable. Specific examples of the negative compound include salicylic acid, naphthoic acid, a metal compound of dicarboxylic acid, a sulfonic acid, a polymer compound having a carboxylic acid in a side chain, a boron compound, a urea compound, a silicon compound, and a curryx arene as a negative compound. As the positive system, a quaternary ammonium salt, a high molecular compound having the quaternary ammonium salt in a side chain, a guanidine compound, an imidazole compound and the like are preferably used. The charge control agent is preferably used in an amount of 0.5 to 10 parts by mass based on 100 parts by mass of the resin.

As the polymerization initiator used in the present invention, for example, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile,
1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis-4-methoxy-2,4-
Azo-based polymerization initiators such as dimethylvaleronitrile and azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-
A peroxide-based polymerization initiator such as dichlorobenzoyl peroxide and lauroyl peroxide is used.

The amount of the polymerization initiator to be added varies depending on the desired degree of polymerization.
0 mass% is added and used. Although the type of the initiator slightly varies depending on the polymerization method, it is used alone or in combination with reference to the 10-hour half-life temperature. Further, in order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor and the like can be further added and used.

In the toner production method of the present invention, the dispersion stabilizer used in the polymerization is preferably an acid-soluble inorganic oxide. Further, the inorganic oxide is preferably a phosphoric acid compound. Examples of the phosphate compound include tricalcium phosphate, magnesium phosphate, aluminum phosphate, and zinc phosphate. These dispersion stabilizers are added in an amount of 0.2 to 100 parts by mass of the polymerizable monomer.
It is preferred to use 10.0 parts by mass.

Further, as the dispersion stabilizer, a commercially available dispersion stabilizer may be used as it is, but in order to obtain finely dispersed particles having a uniform particle size, the inorganic compound is dispersed under high speed stirring in a dispersion medium. It can also be generated. For example, in the case of tricalcium phosphate, a dispersion stabilizer suitable for a suspension polymerization method can be obtained by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring. Further, for the purpose of miniaturization of these dispersion stabilizers, 0.001 to 0.1.
One part by mass of a surfactant may be used in combination.

Specific examples of the surfactant include commercially available nonionic, anionic, and cationic surfactants, such as sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, and sodium oleate. , Sodium laurate, potassium stearate, calcium oleate and the like are preferably used.

The method for producing the polymerization toner of the present invention is specifically carried out as follows.

A release agent, a colorant, a charge control agent, a polymerization initiator and other additives composed of a low-softening substance are added to at least the polymerizable monomer, and are uniformly dissolved or homogenized by a homogenizer, an ultrasonic disperser or the like. The dispersed monomer composition is dispersed in an aqueous phase containing a dispersion stabilizer using a conventional stirrer, homomixer, homogenizer, or the like. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer system.

Preferably, the agitation speed and time are adjusted so that the droplets of the monomer composition have the desired size of the toner particles, and granulation is performed. Thereafter, by the action of the dispersion stabilizer, the particles may be stirred to such an extent that the particle state is maintained and the particles are prevented from settling.

The polymerization temperature is 40 ° C. or higher, generally 50 to
The polymerization is carried out at a temperature of 90 ° C. Further, the temperature may be raised in the latter half of the polymerization reaction, and furthermore, in the latter half of the reaction to remove unreacted polymerizable monomers, by-products, and the like, or by partially distilling the aqueous medium after completion of the reaction. Is also good.

After completion of the reaction, the pH is adjusted, the dispersion stabilizer is dissolved, and the resulting toner particles are collected by filtration, collected by filtration, and dried.

The main feature of the method for producing the polymerization toner of the present invention is that the toner synthesized in an aqueous medium is washed by a filtering means, dehydrated, and the obtained wet colored resin particles are dried by a drying means. In a method for producing a toner by drying to produce a toner, the colored resin particles are separated from the medium by filtration using a vacuum belt filter, and the water content of the colored resin particles after filtration by the belt filter is 35%. It is to be as follows.

Further, in the toner production method of the present invention, when vacuum-filtering with the belt filter, it is preferable that the filter cloth and the vacuum tray are in close contact and do not rub.

The dispersion stabilizer used in the polymerization method generally significantly lowers the charging performance of the toner, so that it is necessary to remove the dispersant. If the dispersant is not completely removed, problems such as a decrease in image density and fogging are likely to occur in an environment where the toner is difficult to be charged.

As a method for removing the dispersion stabilizer, it is general to add an acid or an alkali before dissolving in the medium before filtering off from the medium, and then filter off together with the medium. here,
A small amount of water, which is a medium, adheres to the toner surface after the filtration. The above-mentioned dispersion stabilizer is dissolved in the water, and when the toner to which the water in which the dispersion stabilizer is dissolved is attached is dried in a subsequent process, only the water is removed, and the dissolved dispersion stabilizer is dissolved. The agent is concentrated and adheres to the toner surface.

In order to reduce the residual amount of the dispersion stabilizer by such a filtration method, washing water is added to the water-containing toner after filtration to reduce the concentration of the dispersion stabilizer in the water, and then the mixture is filtered again. There is a method of reducing the amount of the dispersion stabilizer in the adhering water. If necessary, the steps of adding washing water and filtering are repeated several times to make it possible to reduce the amount of the dispersion stabilizer to a desired level or less. Here, the amount of water adhering to the toner after filtration (hereinafter, water content) is important. As described above, since the dispersion stabilizer is concentrated without being removed in the drying step, the remaining amount of the dispersion stabilizer is determined by the product of the concentration of the dispersion stabilizer in the attached moisture and the amount of attached moisture.

Here, as a filtration device used for filtration,
A filtration device having a washing function is preferable. The “washing function” refers to adding washing water to the filtered toner, making the filtered toner into a cake, and passing the washing water through the cake.

As a filtration device having a washing function,
There is a filter press and a belt filter disclosed in JP-A-08-160661. The belt filter allows the washing water to flow evenly over the cake, so it has excellent uniform cleaning properties compared to a filter press, and has the advantage of being smaller than a filter press when compared to the size of the equipment with the same processing capacity, but has the advantage of filtering. After moisture content is 4
There was a problem that it was likely to be as large as about 0%.

If the water content after the filtration is large, 1) the load on the dryer in the post-process increases, leading to an increase in the drying cost. 2) For the reasons described above, the residual amount of the dispersion stabilizer increases, and the toner charging performance decreases, or the cost increases due to an increase in the number of washings. 3) The toner after filtration is not in the form of a cake but in the form of a clay and adheres to the filter cloth, and the entire amount is not discharged in the discharge step, so that the recovery rate is reduced and the filter cloth is easily clogged. There was a problem.

As a result of the study by the present inventors, the water content was 35%.
%, The toner becomes cake-like, and the above-mentioned problems are substantially solved.

In a vacuum type belt filter using a drain screw belt as disclosed in Japanese Patent Application Laid-Open No. 08-160661, vacuum leakage occurs due to the rubbing portion during vacuum filtration, and high vacuum Water content is 3
It is likely to be 5% or more, and it is necessary to provide a washing step for reslurry and the like and a dehydration step such as a centrifugal separator after the belt filter, which is a factor of cost increase. The present inventors have found that a water content of 35% or less can be achieved by a drain screw belt system by adding a function such as adding a pressure roll before vacuum discharge and discharging toner under pressure.

Further, the present inventors have paid attention to the fact that the vacuum leakage caused by the rubbing portion of the drain screw belt system hinders the reduction of the water content, so that the drain screw belt is discarded and the filter cloth is removed during vacuum filtration. It has been found that a belt filter which is in close contact with the vacuum tray and does not rub can achieve a water content of 35% or less more easily than a belt filter of a drain screw belt type. By using a belt filter of a type in which the filter cloth and the vacuum tray do not rub against each other, it is not necessary to provide a washing step and a dehydration step other than the belt filter.

As a belt filter in which the filter cloth and the vacuum tray do not rub during vacuum filtration, the filter cloth is continuously moved to perform vacuum filtration intermittently. There is a vacuum tray reciprocating belt filter that advances the filter cloth at the same speed in the traveling direction, and at the time of a vacuum break, the vacuum tray separates from the filter cloth and then retracts by a distance that has been advanced.

Further, as a belt filter in which the filter cloth and the vacuum tray do not rub against each other at the time of vacuum filtration, the filter cloth is moved intermittently, and the vacuum tray which does not move in the filter cloth running direction only when the filter cloth is stopped is brought into close contact with the filter cloth. There is a filter cloth intermittent movement type belt filter in which vacuum filtration is carried out and the vacuum tray is separated from the filter cloth when the filter cloth is moved.

A method for filtering and washing toner particles, which is a feature of the present invention, will be specifically described with reference to the drawings.

FIGS. 1 to 3 are schematic sectional views showing an example of the belt filter used in the present invention.

The drain screw belt type belt filter shown in FIG. 1 is stretched between a plurality of rolls 1 and a filter cloth 3 is arranged on an endless drain screw belt 2 continuously driven in the direction of arrow A. , Below the drain screw belt 2
It has a structure in which a fixed type vacuum tray 4 divided into a body or a plurality is installed. The slurry in which the dispersion stabilizer is dissolved is filtered from the upper part of the filter surface through the liquid sending port 5 through the filter cloth 3.
It is supplied above and filtered and dewatered by the action of vacuum. The filtrate is collected in a vacuum tray and sent from a filtrate tube (not shown) to a vacuum tank (not shown). The filtered cake 6 and the filter cloth 3 travel together with the drain screw belt 2, during which a washing liquid is sprayed from one or more cake washing devices 7 from above, and the soluble substances in the cake 6 are discharged together with the filtrate. It is supposed to be. The dewatered cake 6 is separated from the filter cloth 3 by a curvature provided by the roll 1 or a discharge roll (not shown) after being dewatered under pressure by the pressurizing device 8.

The vacuum filter reciprocating type belt filter shown in FIG. 2 is stretched between a plurality of rolls 1 and is provided below an endless filter cloth 3 continuously driven in the direction of arrow A. A plurality of divided vacuum trays 4 are provided, and the vacuum tray 4 has a structure that reciprocates in the arrow B direction.
The slurry in which the dispersion stabilizer is dissolved is supplied onto the filter cloth 3 from the upper part of the filtration surface through the liquid feed port 5, and is filtered and dehydrated by intermittent vacuum action. The filtrate is collected in a vacuum tray and sent from a filtrate tube (not shown) to a vacuum tank (not shown). The filtered cake 6 travels together with the filter cloth 3, during which the washing liquid is sprayed from one or more cake washing devices 7 from above, and the soluble substances in the cake 6 are discharged together with the filtrate. ing. Dehydrated cake 6
Is separated from the filter cloth 3 by a curvature provided by the roll 1 or a discharge roll (not shown).

The filter cloth intermittent movement type belt filter shown in FIG. 3 is stretched between a plurality of rolls 1 and is provided below the endless filter cloth 3 intermittently driven in the direction of arrow A by one or more. Has a structure in which a fixed vacuum tray 4 divided into a plurality of sections is provided. The slurry in which the dispersion stabilizer is dissolved is supplied onto the filter cloth 3 from the upper part of the filtration surface through the liquid feed port 5, and is filtered and dehydrated by intermittent vacuum action. The filtrate is collected in a vacuum tray and sent from a filtrate tube (not shown) to a vacuum tank (not shown). Filtered cake 6
It travels together with the filter cloth 3, during which the washing liquid is sprayed from one or more cake washing devices 7 from above, and the soluble substances in the cake 6 are discharged together with the filtrate. The dehydrated cake 6 is separated from the filter cloth 3 and discharged by a curvature provided by the roll 1 or a discharge roll (not shown).

The discharged cake is dried by a dryer such as a fluidized bed dryer, a flash dryer and a vacuum dryer.

An external additive may be added to the toner of the present invention for imparting various toner properties. Examples of the external additive used include metal oxides (aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide, chromium oxide, tin oxide, zinc oxide, etc.).
・ Nitride (silicon nitride, etc.) ・ Carbide (silicon carbide, etc.) ・ Metal salts (calcium sulfate, barium sulfate, calcium carbonate, etc.) ・ Fatty acid metal salts (zinc stearate, calcium stearate, etc.) ・ Carbon black, silica, etc. Can be

These external additives are used in an amount of 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the toner particles. These external additives may be used alone or in combination. Those subjected to a hydrophobizing treatment are more preferable.

A Coulter Counter TA-II or Coulter Multisizer II (manufactured by Coulter Inc.) is used as a device for measuring the toner flat diameter and particle size distribution. As the electrolyte, about 1% NaCl aqueous solution is prepared using primary sodium chloride. The measuring method is as follows.
0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 00 to 150 ml, and 2 to 20 mg of a measurement sample is further added.

The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume and number of the toner were measured by using the measuring device with a 100 μm aperture as the aperture. The distribution and number distribution were calculated.

Then, a weight-based weight average particle diameter (D4) (representative value of each channel is set as a representative value of each channel) determined from the volume distribution according to the present invention was determined.

The water content in the present invention was determined by collecting 5 g of water-containing particles in an aluminum dish, weighing the fine particles (A [g]),
It is left for 1 hour in a dryer set at 105 ° C., cooled, precisely weighed (B [g]), and calculated by the following equation.

Water content = ((AB) / A) × 100
[%]

[0074]

The basic structure and features of the present invention have been described above. Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples of the present invention. However, of course, this does not limit the invention in any way.

Example 1 450 parts by mass of an aqueous 0.1 M Na ₃ PO ₄ solution were charged into 700 parts by mass of ion-exchanged water, heated to 60 ° C., and then Clearmix CLS-30.
4500 rpm using S (manufactured by M Technique Co., Ltd.)
And stirred. 1.0M-CaCl ₂ aqueous solution 68
Parts by mass were gradually added to obtain an aqueous medium containing a calcium phosphate salt.

On the other hand, (monomer) 170 parts by mass of styrene 30 parts by mass of n-butyl acrylate (colorant) I. Pigment Blue 15: 3 10 parts by mass (Charge control agent) Di-t-butylsalicylate metal compound 2 parts by mass (polar resin) Saturated polyester 15 parts by mass (acid value 10 mgKOH / g, peak molecular weight: 8500) (release agent) Ester wax (melting point: 65 ° C.) 40 parts by mass The above formulation was heated to 60 ° C., and was uniformly dissolved and dispersed. Into this, 8 parts by mass of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.

The polymerizable monomer composition was charged into the aqueous medium, and the mixture was stirred at 4500 rpm for 15 minutes in a clear mix at 60 ° C. in an N ₂ atmosphere to granulate the polymerizable monomer composition. did.

Thereafter, while stirring with a paddle stirring blade, 70
C., and reacted for 10 hours. After the completion of the polymerization reaction, 8
The residual monomer was distilled off at 0 ° C./reduced pressure, and after cooling, hydrochloric acid was added to dissolve the calcium phosphate salt. Then, using a drain screw belt type belt filter (manufactured by Sumitomo Heavy Industries, Ltd., Eagle filter), After dehydration and washing under the conditions described above, a wet cake of polymerized toner particles was obtained.

Drain screw belt type belt filter
Dewatering / washing conditions Filtration area: 0.1 m ² Slurry supply amount: 40 kg / h Belt speed: 0.35 m / min Wash water amount: 20 kg / h Vacuum degree: -53 kPa Pressure linear pressure: 900 Pa

The water content of the wet cake obtained as described above was 35%. Thereafter, drying was performed to obtain colored resin particles.

[Evaluation of Cleaning State] The cleaning state was evaluated by the amount of the remaining dispersion stabilizer. The amount of the remaining dispersion stabilizer was quantitatively analyzed using a fluorescent X-ray analyzer (RIX3000). When the value of the residual dispersion stabilizer is 200 ppm
In the following cases, there is no substantial problem, but if it exceeds 200 ppm, the chargeability of the toner decreases. The amount of the residual dispersion stabilizer in this example was 196 ppm, which is a level that is not a problem, but was the upper limit.

To 100 parts by mass of the colored particles obtained above, 1.0 part by mass of hydrophobic silica having a specific surface area of 200 m ² / g by the BET method was added, and the mixture was mixed with a mixer to obtain a toner. Obtained. The weight average particle size of the toner obtained in this example was 6.8 μm.

[Evaluation of Image Performance]
An endurance test was performed on 3000 sheets continuously in an environment of 80 ° C. and 80% humidity, and fog was measured and evaluated. The durability test was performed using LBP-2360 manufactured by Canon Inc.

For fogging on paper, use a reflection type densitometer (TOKYODENSHOKUCO., LTD, RE
FLECTOMETER ODEL TC-6DS). That is, the worst value of the reflection density of the pudding and the white background portion measured by the reflection densitometer is Ds, and the average reflection density of the paper before printing measured by the reflection densitometer is D
r, the difference (Ds−Dr) between these values is determined,
This was designated as fog on paper. When the amount of fogging on paper was 2% or less, a good image having substantially no fogging on paper was obtained, but when it exceeded 2%, an unclear image in which fogging on paper was conspicuous.

In the present example, evaluation was performed on the image after 3,000 sheets of durability, and although fog temporarily exceeded 2% during the durability, the fog level was no problem.

<Comparative Example 1> A wet cake of polymerized toner particles was obtained by performing the same operation as in Example 1 except that the pressurized dehydration linear pressure was changed to 0 Pa under the dewatering / washing conditions of Example 1.

The water content of the obtained wet cake was 38%. Thereafter, drying was performed to obtain colored resin particles.

The toner thus obtained was evaluated for the cleaning state in the same manner as in Example 1. As a result, the amount of the residual dispersion stabilizer was 323 ppm, which exceeded the allowable range.

Further, using the toner obtained above, an image-drawing test was carried out by externally adding the toner in the same manner as in Example 1, and the fog was confirmed. The image frequently increased, and the image was at a level that was not practical.

<Example 2> Using the prescription of Example 1, a dewatering / washing device was performed under the following conditions using a vacuum tray reciprocating belt filter as shown in FIG. The same operation as in Example 1 was performed to obtain a wet cake of polymerized toner particles.

The belt filter of the vacuum tray reciprocating type
Dewatering / washing conditions Filtration area: 0.7 m ² Slurry supply amount: 400 kg / h Belt speed: 1.4 m / min Wash water amount: 190 kg / h Vacuum degree: -72 kPa

The water content of the obtained wet cake was 28%. Thereafter, drying was performed to obtain colored resin particles.

The toner thus obtained was evaluated for the cleaning state in the same manner as in Example 1. As a result, the amount of the remaining dispersion stabilizer was 121 ppm, which was a level that was not a problem.

Further, using the toner obtained above, an external image addition test was carried out in the same manner as in Example 1, and a fog test was carried out. As a result, the fog was found to be 2% over 3000 sheets.
, And a high-quality image could be stably obtained.

<Example 3> Using the prescription of Example 1, a dewatering / washing device was performed using a filter cloth intermittent movement type belt filter as shown in FIG. 3 under the following conditions. The same operation as in Example 1 was performed to obtain a wet cake of polymerized toner particles.

Dehydration of belt cloth of intermittent movement type of filter cloth
・ Washing conditions Filtration area: 0.15 m ² Slurry supply amount: 90 kg / h Belt speed: Stop time / moving time = 10/1, average 0.7 m / min Wash water amount: 42 kg / h Vacuum degree:- 68 kPa

The water content of the wet cake obtained as described above was 33%. Thereafter, drying was performed to obtain colored resin particles.

The toner thus obtained was evaluated for the cleaning state in the same manner as in Example 1. As a result, the amount of the remaining dispersion stabilizer was 157 ppm, which was a level that was not a problem.

Further, using the toner obtained above, an image-drawing test was conducted by externally adding the toner in the same manner as in Example 1, and the fog was confirmed.
, And a high-quality image could be stably obtained.

Example 4 450 parts by mass of a 0.1 M Na ₃ PO ₄ aqueous solution were charged into 700 parts by mass of ion-exchanged water, heated to 60 ° C., and then Clearmix CLS-30.
4500 rpm using S (M, Technique)
And stirred. 1.0M-CaCl ₂ aqueous solution 68
Parts by mass were gradually added to obtain an aqueous medium containing a calcium phosphate salt.

On the other hand, (monomer) styrene 170 parts by mass n-butyl acrylate 30 parts by mass (coloring agent) Silane-coupling-treated magnetic material 180 parts by mass (charge control agent) di-t-butylsalicylate metal compound 2 parts by mass ( (Polar resin) Saturated polyester 15 parts by mass (acid value 10 mg KOH / g, peak molecular weight: 8500) (release agent) Ester wax (melting point 65 ° C) 8 parts by mass The above formulation is heated to 60 ° C and uniformly dissolved. Dispersed. Into this, 8 parts by mass of a polymerization initiator tert-butylperoxy-2-ethylhexanate was dissolved to prepare a polymerizable monomer composition.

The polymerizable monomer composition was charged into the aqueous medium, and the mixture was stirred at 4500 rpm at 60 ° C. in a N ₂ atmosphere at 4500 rpm for 15 minutes to granulate the polymerizable monomer composition. did.

Thereafter, while stirring with a paddle stirring blade, 70
C., and reacted for 10 hours. After the completion of the polymerization reaction, sodium carbonate was added for the purpose of dissolving the residue of the polymerization initiator, the remaining monomers were distilled off at 80 ° C./reduced pressure, and after cooling, a reciprocating belt of a vacuum tray as shown in FIG. Using a filter, dehydration and washing were performed under the following conditions to obtain a wet cake of polymerized toner particles. The washing was divided into three zones, and washing was performed in the order of washing water, hydrochloric acid, and washing water.

The vacuum tray reciprocating belt filter
Dewatering / washing conditions Filtration area 0.7 m ² Slurry supply amount: 400 kg / h Belt speed: 1.4 m / min Amount of washing liquid: (water) 30 parts by mass (hydrochloric acid) 40,
(Water) 120 kg / h Vacuum degree: -72 kPa

The water content of the wet cake obtained as described above was 24%. Thereafter, drying was performed to obtain colored resin particles.

The toner thus obtained was evaluated for the cleaning state in the same manner as in Example 1. As a result, the amount of the remaining dispersion stabilizer was 78 ppm, which was a level that was not a problem.

Further, the toner obtained above was externally added in the same manner as in Example 1 to perform an image formation test, and the fog was confirmed. As a result, the fog was found to be 2% over 3000 sheets.
, And a high-quality image could be stably obtained.

[0108]

As described above, according to the present invention,
Provided is a method for producing a polymerization toner capable of efficiently cleaning the surface of each toner particle uniformly and obtaining a toner having excellent image characteristics without causing fogging or the like when an image is formed with the obtained toner. Is done.

Further, according to the present invention, there is provided a method for producing a polymerization toner capable of stably obtaining a high-quality image even in a high-temperature and high-humidity environment and obtaining a durable toner.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a belt filter used in the present invention.

FIG. 2 is a schematic sectional view of a belt filter used in the present invention.

FIG. 3 is a schematic sectional view of a belt filter used in the present invention.

[Explanation of symbols]

 Reference Signs List 1 roll 2 drain screw belt 3 filter cloth 4 vacuum tray 5 liquid feed port 6 cake 7 cake washing device 8 pressurizing device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroaki Kataoka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Ryuichi Monoi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term in the company (reference) 2H005 AB06 EA10

Claims (4)

[Claims] 1. A method for producing a toner in which a toner synthesized in an aqueous medium is washed by a filtration means, dehydrated, and the obtained wet colored resin particles are dried by a drying means to produce a toner. Producing a polymerized toner, wherein the colored resin particles are separated from the medium by filtration using a vacuum belt filter, and the water content of the colored resin particles after filtration by the belt filter is 35% or less. Method. 2. The method according to claim 1, wherein the filter cloth and the vacuum tray are in close contact with each other and do not rub during vacuum filtration with the belt filter. 3. The belt filter according to claim 2, wherein said belt filter is a vacuum tray reciprocating belt filter.
3. The method for producing a polymerization toner according to item 1. 4. The method according to claim 2, wherein the belt filter is a filter cloth intermittent movement type belt filter.