JP2001092184A - Method for manufacturing polymerization process toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing polymerization process toners which have desired grain sizes, have a uniform grain size distribution and are unified in shape to a spherical shape while preventing the contamination of the device by a continuous polymerization method. SOLUTION: The method for manufacturing the polymerization process toners which manufacture colored particles by suspending a monomer composition containing at least a polymerizable monomer and coloring agents as very small liquid drops in an aqueous dispersion medium containing a dispersion stabilizer, then subjecting the composition to suspension polymerization in the presence of a polymerization initiator is the method for manufacturing the polymerization process toners consisting in (a) charging the first suspension prepared by suspending the very small liquid drops of the monomer composition into the aqueous dispersion medium containing the dispersion stabilizer and effecting the suspension polymerization until the transfer rate of the polymerizable monomer attains at least 90%, and (2) after adding the aqueous dispersion liquid of the dispersion stabilizer into a reactor or while continuously or intermittently adding the aqueous dispersion liquid thereto, (3) continuously adding the second suspension suspended with the very small liquid drops of the monomer composition into the aqueous dispersion medium containing the dispersion stabilizer within the reactor and continuing the suspension polymerization in the presence of the polymerization initiator and (4) continuously withdrawing the reaction liquid of at least 90% in the transfer rate of the polymerizable monomer from the reactor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polymerization toner used for image formation by electrophotography, electrostatic recording, or the like.
The present invention relates to a method for producing a polymerization toner having a desired particle size, a uniform particle size distribution, and a spherical shape while preventing contamination of the apparatus.

[0002]

2. Description of the Related Art In image formation by electrophotography or electrostatic recording, toner is used alone or in combination with carrier particles or a fluidizing agent as a developer for visualizing an electrostatic latent image on a photoreceptor. Have been. The toner is a colored particle in which a colorant such as carbon black and other additives are dispersed in a binder resin. As a method for producing the toner, a pulverization method and a polymerization method are known.

In particular, according to the polymerization method, it is easier to obtain a toner having a desired particle size and particle size distribution and a shape close to a true sphere, as compared with the pulverization method. In the polymerization method, generally,
Prepare a monomer composition (uniform mixture) containing a polymerizable monomer such as styrene or acrylate, a colorant, and other additives as necessary, and add this to a dispersion stabilizer. Into a water-based dispersion medium to be dispersed and dispersed using a mixing device having a high shear force, granulate the monomer composition into fine droplets, and then raise the temperature in the presence of a polymerization initiator. By performing suspension polymerization, colored particles (polymerized toner) are obtained. The polymerization reaction is a method in which a suspension containing fine droplets of the monomer composition is charged into a tank reactor, and suspension polymerization is performed while stirring in the tank reactor, that is, a batch polymerization method ( Batch polymerization method).

However, in the conventional method for producing a polymerization toner by a batch polymerization method, scale (adhered matter) is easily generated in each part of the tank reactor, and after several batches of polymerization,
Cleaning work is required to remove dirt from the apparatus. If the scale is left untreated, the peeled pieces of the scale may mix into the polymerized toner, cause clogging of the piping, or reduce the thermal conductivity of the reactor. The cleaning operation for removing the contamination of the apparatus requires time and labor, and during that time, the polymerization reaction using the reactor must be stopped, which causes a problem in productivity.

[0005]

If a continuous polymerization method is used instead of a batch polymerization method, a relatively small apparatus can be used.
It is expected that a polymer can be produced with high productivity. However, in the continuous polymerization method, the unreacted monomer is continuously added to the reaction system for polymerization, and simultaneously, the reaction product is continuously extracted from the reaction system. It is very difficult to control the distribution. In the continuous polymerization method, newly added unreacted monomer droplets come into contact with already generated polymer particles to cause coalescence or separation, so that irregularly shaped particles or fine particles are easily generated. On the other hand, the toner may have a desired particle size, a narrow particle size distribution, and a spherical shape.
Indispensable for forming high quality images. Therefore, simply applying the continuous polymerization method to a method for producing a polymerization toner cannot provide a polymerization toner having satisfactory properties. Actually, in the field of polymerization toner, a continuous polymerization method has not been conventionally employed, but a batch polymerization method has been employed exclusively (for example, see JP-A-9-106).
No. 100, JP-A-10-177278, etc.).

An object of the present invention is to produce a polymerization toner having a desired particle size, a uniform particle size distribution, and a spherical shape by a continuous polymerization method while preventing contamination of the apparatus. It is to provide a method.

The present inventors have conducted research on producing a polymerization toner by a continuous polymerization method. As a result, the first suspension was charged into a reactor, and suspension polymerization was carried out in the presence of a polymerization initiator. After sufficiently increasing the polymerization conversion rate, the aqueous dispersion of the dispersion stabilizer is continuously or intermittently added into the reactor to freely disperse the dispersion stabilizer in the reaction system, and the dispersion stabilizer is free. It has been found that when the second suspension is continuously added in a dispersed state to carry out continuous polymerization, colored particles having a target particle size and a particle size distribution can be obtained. The obtained colored particles are polymerization toner having a shape close to a true sphere. In addition, according to this method, the generation of scale in the reactor can be significantly suppressed. The present invention has been completed based on these findings.

[0008]

According to the present invention, a monomer composition containing at least a polymerizable monomer and a colorant is dispersed in an aqueous dispersion medium containing a dispersion stabilizer. In the method for producing a polymerized toner, which is suspended in the form of droplets and then subjected to suspension polymerization in the presence of a polymerization initiator to produce colored particles, (1) an aqueous dispersion containing a dispersion stabilizer in a reactor. A first suspension of fine droplets of the monomer composition suspended in a medium is charged and suspended in the presence of a polymerization initiator until the conversion of the polymerizable monomer is at least 90%. After conducting the suspension polymerization, and then (2) adding the aqueous dispersion of the dispersion stabilizer into the reactor, or continuously or intermittently, adding the dispersion stabilizer into the reactor (3). A second suspension of fine droplets of the monomer composition suspended in an aqueous dispersion medium containing (4) A polymerization toner characterized in that the suspension polymerization is continued in the presence of a polymerization initiator, and (4) a reaction solution having a conversion of a polymerizable monomer of at least 90% is continuously withdrawn from a reactor. Is provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Raw Materials In the present invention, a monomer composition containing at least a polymerizable monomer and a colorant is used. The monomer composition includes, in addition to the polymerizable monomer and the colorant, various components such as a crosslinkable monomer, a macromonomer, a charge control agent, a release agent, a molecular weight regulator, a lubricant, and a dispersion aid. Can be contained.

[0010] 1. Polymerizable monomer In the present invention, a vinyl monomer is generally used as the polymerizable monomer. The glass transition temperature (Tg) of the polymer can be adjusted to a desired range by using various vinyl monomers alone or in combination of two or more. As the vinyl monomer used in the present invention, for example, styrene, vinyl toluene, α-
Styrene-based monomers such as methylstyrene; acrylic acid;
Methacrylic acid; methyl acrylate, ethyl acrylate,
Propyl acrylate, butyl acrylate, acrylic acid 2
-Ethylhexyl, dimethylaminoethyl acrylate,
Derivatives of (meth) acrylic acid such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dimethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide; ethylene, Ethylenically unsaturated monoolefins such as propylene and butylene; vinyl chloride, vinylidene chloride,
Vinyl halides such as vinyl fluoride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone and methyl isopropenyl ketone; 2-vinylpyridine; Nitrogen-containing vinyl compounds such as vinylpyridine and N-vinylpyrrolidone; and mixtures thereof. Among these, a combination of a styrene monomer and a derivative of (meth) acrylic acid is preferable.

2. Crosslinkable monomer It is preferable to use a crosslinkable monomer together with the polymerizable monomer from the viewpoint of improving hot offset of the polymerization method toner.
Examples of the crosslinkable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; ethylene glycol dimethacrylate;
Examples include ethylenically unsaturated dicarboxylic acid esters such as diethylene glycol dimethacrylate; divinyl compounds such as N, N-divinylaniline and divinyl ether; compounds having three or more vinyl groups; and mixtures thereof. The crosslinkable monomer is a polymerizable monomer 10
It is used in an amount of usually 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, based on 0 parts by weight.

3. Macromonomer In order to improve the balance of preservability, offset property, and low-temperature fixability of the polymerization method toner, together with a polymerizable monomer,
Macromonomers can be used. A macromonomer is a relatively long linear molecule having a polymerizable functional group (for example, an unsaturated group such as a carbon-carbon double bond) at the end of a molecular chain. The macromonomer has a vinyl polymerizable functional group (for example, an acryloyl group or a methacryloyl group) at a molecular chain terminal, and has a number average molecular weight of 1,
About 000 to 30,000 oligomers or polymers are preferred.

Examples of the macromonomer include styrene, styrene derivatives, methacrylates, acrylates, acrylonitrile, methacrylonitrile, and the like, or a polymer obtained by polymerizing two or more kinds; a polysiloxane skeleton. Having a macromonomer; those disclosed in JP-A-3-203746. The usage ratio of the macromonomer is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the polymerizable monomer.

4. Colorant As the colorant, various pigments and dyes such as carbon black and titanium white can be used. The carbon black preferably has a primary particle size of 20 to 40 nm. If the primary particle size of the carbon black is too small, the dispersibility decreases, and the toner tends to be fogged. If the primary particle size is too large, the content of the polyvalent aromatic hydrocarbon compound increases, and Problem easily occurs.

When a color toner is obtained, a yellow colorant, a magenta colorant, a cyan colorant, and the like are generally used as colorants. As the yellow colorant, compounds such as azo pigments and condensed polycyclic pigments are used. More specifically, for example, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 7
3, 83, 90, 93, 97, 120, 138, 15
5, 180, 181 and the like.

As the magenta colorant, compounds such as azo pigments and condensed polycyclic pigments are used. More specifically, for example, C.I. I. Pigment Red 48, 57, 5
8, 60, 63, 64, 68, 81, 83, 87, 8
8, 89, 90, 112, 114, 122, 123, 1
44, 146, 149, 163, 170, 184, 18
5,187,202,206,207,209,25
1; I. Pigment Violet 18 and the like.

As the cyan coloring agent, compounds such as copper phthalocyanine compounds and derivatives thereof, and anthraquinone compounds are used. More specifically, for example, C.I. I.
Pigment Blue 2, 3, 6, 15: 1, 15: 2, 1
5: 3, 15: 4, 16, 17, 60 and the like.
The coloring agent is used in a proportion of usually 0.1 to 50 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the polymerizable monomer.

5. Charge Control Agent In the present invention, various charge control agents having positive chargeability or negative chargeability can be used in order to improve the chargeability of the polymerization toner. Specifically, examples of the charge control agent include a metal complex of an organic compound having a carboxyl group or a nitrogen-containing group, a metal-containing dye, and nigrosine. More specifically, Bontron N-01 (manufactured by Orient Chemical), Nigrosine Base EX (manufactured by Orient Chemical), Spiron Black TRH (manufactured by Hodogaya Chemical),
T-77 (Hodogaya Chemical), Bontron S-34
(Orient Chemical Co.), Bontron E-89 (Orient Chemical Co.), Bontron E-84 (Orient Chemical Co.), Bontron F-21 (Orient Chemical Co.),
Copy Charge NX VP434 (made by Hoechst Industry), Copy Charge NEG VP2036 (made by Hoechst Industry), quaternary ammonium (salt)
Charge control resins such as a sulfonic acid (salt) group-containing resin. The charge control agent is usually 0.01 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer,
Preferably, it is used in a proportion of 0.05 to 7 parts by weight.

6. Release Agent In the present invention, a release agent can be used to improve the release property of the polymerization toner. As a release agent,
For example, polyfunctional ester compounds; low molecular weight polyolefins such as low molecular weight polyethylene, low molecular weight polypropylene and low molecular weight polybutylene; paraffin waxes which are naturally derived waxes; synthetic waxes such as Fischer Tropsch wax; . Of these, polyfunctional ester compounds are preferred.

Specific examples of the polyfunctional ester compound include:
Examples thereof include pentaerythritol tetrastearate, pentaerythritol tetramyristate, and glycerol triaraquinic acid. It is preferable that the polyfunctional ester compound be easily soluble in the polymerizable monomer.
Among the polyfunctional ester compounds, pentaerythritol tetrastearate and pentaerythritol tetramyristate are particularly preferred. It is preferable that ordinary waxes are pulverized or melted and dispersed when mixed with the polymerizable monomer. The release agent is usually 0.1 to 40 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer.
Used in parts by weight. By using the release agent in the above ratio, the low-temperature fixability can be improved.
If the use ratio of the release agent is too small, the effect of improving the low-temperature fixability is small, and if it is too large, the blocking resistance decreases.

7. In the present invention, in order to adjust the molecular weight of the polymerization toner,
Molecular weight regulators can be used. Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, and n-octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride and carbon tetrabromide; and the like. These molecular weight modifiers are usually contained in the polymerizable monomer before the start of the polymerization, but can be added to the reaction system during the polymerization, if desired. The usage ratio of the molecular weight modifier is usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer.

8. Lubricant and dispersing aid In the present invention, for example, oleic acid, stearic acid, various waxes, polyethylene, polypropylene, for the purpose of improving the uniform dispersibility of the polymerizable monomer and the colorant in the polymerized toner. And various dispersing agents such as silane or titanium coupling agents. Such a lubricant or dispersant is usually 1/1000 to 100% based on the weight of the colorant.
Used at a rate of about 1/1.

As the polymerization initiator , a radical polymerization initiator is usually used. Examples of the radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate;
-Azobis (4-cyanovaleric acid), dimethyl-2,2 '
-Azobis (2-methylpropionate), 2,2'-
Azobis (2-amidinopropane) dihydrochloride, 2,2 '
-Azobis-2-methyl-N-1,1-bis (hydroxymethyl) -2-hydroxyethylpropioamide,
2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile,
1'-azobis (1-cyclohexanecarbonitrile)
Azo compounds such as methyl ethyl peroxide, di-t
-Butyl peroxide, acetyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-isopropylperoxydicarbonate, di-t-butylperoxy Peroxides such as isophthalate; and the like. A redox initiator combining these polymerization initiators and a reducing agent can also be used.

Among these radical polymerization initiators, oil-soluble radical initiators are preferable. In particular, t-butylpaoxy-2-ethylhexanoate and t-butylperoxyneodecanoate are used when printing a polymerized toner. It is particularly suitable because it has low odor and little environmental destruction due to volatile components. The ratio of the polymerization initiator used is as follows.
The amount is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight based on 00 parts by weight. The use ratio of the polymerization initiator is usually 0.001 to 5% by weight based on the aqueous dispersion medium. If the use ratio of the polymerization initiator is too small, the polymerization rate will be slow, and if it is too large, it is not economical.

Dispersion Stabilizer A monomer composition containing a polymerizable monomer, a colorant, and, if necessary, various additives is introduced into an aqueous dispersion medium containing a dispersion stabilizer to form a fine particle. Granulate into droplets. As the dispersion stabilizer, a colloid of a poorly water-soluble metal compound is preferable. Examples of poorly water-soluble metal compounds include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide; Aluminum oxide, magnesium hydroxide,
Metal hydroxides such as ferric hydroxide; and the like. Among these, colloids of poorly water-soluble metal hydroxides can narrow the particle size distribution of fine droplets of the monomer composition and colored particles (polymerized toner), and improve image clarity. Therefore, it is preferable.

These colloids have a desired particle size and particle size distribution because they adhere to minute droplets of the monomer composition and the surface of the resulting colored polymer particles to form a protective layer. It is preferable in order to stably obtain colored particles having a spherical shape. In addition, prior to the continuous polymerization step, when an aqueous dispersion containing a dispersion stabilizer is added to the reaction system, the polymer particles are freely dispersed, and newly added unreacted monomer droplets are already formed. By contacting, the occurrence of coalescence and separation can be prevented. The colloid of the poorly water-soluble metal hydroxide is not limited by the production method, but can be suitably prepared by adjusting the pH of the aqueous solution of the water-soluble polyvalent metal compound to 7 or more, whereby An aqueous dispersion medium containing a metal hydroxide colloid can be obtained.

The dispersion stabilizer is usually used in a proportion of 0.1 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer.
If this ratio is too small, it is difficult to obtain sufficient polymerization stability, and a polymerized aggregate is easily formed. If this ratio is too large, the viscosity of the aqueous dispersion medium increases, and the particle size distribution of the polymerized toner becomes wider. In the present invention, a water-soluble polymer such as polyvinyl alcohol, methylcellulose, gelatin or the like, or a surfactant may be added in order to homogenize the droplet particles.

Suspension In the present invention, a suspension is used in which fine droplets of the monomer composition are suspended in an aqueous dispersion medium containing a dispersion stabilizer. This suspension is prepared by suspending a monomer composition containing at least a polymerizable monomer and a colorant as fine droplets in an aqueous dispersion medium containing a dispersion stabilizer. Can be. More specifically, a polymerizable monomer and a colorant, and further, if necessary, various components such as a macromonomer, a crosslinkable monomer, a dispersing aid, a charge controlling agent, and a molecular weight modifier are mixed, A uniform mixture is prepared by uniformly dispersing with a bead mill or the like, and then the mixed solution is poured into an aqueous dispersion medium containing a dispersion stabilizer, and dispersed using a mixing device having a high shear force. A suspension is prepared by granulating into fine droplets.

The polymerization initiator is preferably added to the aqueous dispersion medium before the completion of granulation of the monomer composition into fine droplets. The timing of adding the polymerization initiator varies depending on the target particle diameter of the polymerization method toner, but after the introduction of the monomer composition, the volume average particle diameter of the primary droplet of the monomer composition formed by stirring is changed. , Usually 50 to 1000 μm, preferably 1
It is at the time when it becomes 00 to 500 μm. If the time from the introduction of the monomer composition to the aqueous dispersion medium to the addition of the polymerization initiator is too long, the granulation of fine droplets is completed, and the polymerization initiator coalesces with the droplets. Can be difficult.
For this reason, although the timing of adding the polymerization initiator varies somewhat depending on the particle size and the reaction scale, it is generally within 24 hours, preferably 12 hours, on the plant scale after the introduction of the monomer composition. Within an hour, more preferably within 3 hours, and on a laboratory scale, usually within 5 hours, preferably within 3 hours, more preferably within 1 hour. From the time of addition of the polymerization initiator, to the subsequent granulation step, and further to the addition to the polymerization reaction system, the temperature of the aqueous dispersion medium is
It is usually desirable to adjust the temperature within the range of 10 to 40 ° C, preferably 20 to 30 ° C. Immediately before being charged into the polymerization reaction system, the temperature of the suspension containing the fine droplets of the monomer composition can be raised to, for example, about 40 to 50 ° C. to carry out a preliminary reaction.

In the granulation step, the primary droplets are dispersed into secondary droplets having a particle size and a particle size distribution corresponding to the target particle size and the particle size distribution of the polymerized toner, thereby forming fine particles. Granulate the droplets. The volume average particle diameter (dv) of the fine droplets of the monomer composition is usually 0.1 to 50 μm, preferably 0.5 to 50 μm.
It is about 30 to 30 m, more preferably about 1 to 20 m, and particularly preferably about 3 to 15 m. The particle size distribution represented by the ratio (dv / dp) between the volume average particle size (dv) and the number average particle size (dp) is usually 3.0 or less, preferably 2.5 or less,
It is more preferably 2.0 or less. The lower limit of the particle size distribution is
Usually, it is about 1.0. If the particle size distribution of the droplets is too wide, the fixing temperature of the resulting polymerized toner will vary, which will tend to cause inconveniences such as fogging and toner filming. The concentration of the polymerizable monomer in the aqueous dispersion medium is usually about 5 to 40% by weight, preferably about 8 to 30% by weight. If the concentration of the polymerizable monomer is too low, the productivity will decrease. If the concentration of the polymerizable monomer is too high, the particle size distribution tends to increase, and the particle size of the obtained colored particles tends to increase. In the present invention, it is possible to use a suspension having the same formulation as the first suspension and the second suspension to stabilize colored particles having a target particle size and a particle size distribution by continuous polymerization. It is preferable because it is easily obtained.

In order to granulate fine droplets of the monomer composition, a stirrer capable of high-shear stirring such as a TK homomixer is usually used. Further, using a granulating apparatus including a rotor that rotates at a high speed and a stator surrounding the rotor and having small holes or comb teeth, a monomer composition is provided in a gap between the rotor and the stator. The monomer composition can be granulated into droplets having a fine particle size by flowing an aqueous dispersion medium containing (WP98 / 25186). Examples of such a granulating apparatus include M-Technic Co., Ltd.'s clearmix (cleamix), Ebara Manufacturing Co., Ltd.'s Ebara Milder, and the like.

Continuous polymerization method First Step In the continuous polymerization method, as a first step, a first suspension in which minute droplets of the monomer composition are suspended in an aqueous dispersion medium containing a dispersion stabilizer in a reactor. And a polymerization reaction is started in the presence of a polymerization initiator. In the first step, suspension polymerization is performed by a batch polymerization method until the conversion of the monomer becomes at least 90%. Typical examples of the reactor include an annular reactor (loop reactor) 1 as shown in FIG. 1 and a tank reactor 21 as shown in FIG. The first suspension may be prepared in the reactor, but the suspension should be prepared in a separate container and then put into the reactor to suppress the formation of scale and coarse particles. Is preferred.

In the annular reactor 1 shown in FIG.
From the first suspension by feed pump 10 to line 8
And introduced into the annular reactor 1. The first suspension is
You may put in from the line 7. The interior of the annular reactor is previously replaced with an inert gas such as nitrogen gas. The amount of the suspension to be charged is preferably such that the gaseous phase remains as little as possible in the annular reactor. Since the suspension expands as the reaction temperature increases, the amount of the suspension to be charged is set in consideration of the expansion. The first suspension charged in the annular reactor is circulated in the annular reactor by using the circulation pump 2 or the stirrer 3 or by using both of them. The circulation pump is preferably a line pump type in which the suspension enters from the side and exits from the side. As the stirrer, a stirrer having a stirring blade such as a spiral band blade, an inclined paddle, a spiral shaft blade, or the like can be used. The flow rate (suspension in a pipe) of the suspension in the annular reactor is usually 0.5 to 10 m / sec, preferably 1 to 10 m / sec.
At about 5 m / sec, the suspension is circulated and a swirling flow is generated to prevent the scale from adhering to various parts in the pipe and the sedimentation of particles. In the annular reactor, it is preferable that the inside of the tube is buffed and the number of nozzles attached is kept to a minimum to prevent contamination and adhesion of scale. The curved tube section is a long elbow having a large R, for example, JI
A long elbow specified by the piping standard of S is preferable. In addition, the curved pipe portion is preferably a 180 ° long elbow having no straight pipe portion because it has no stagnation portion inside.

The suspension polymerization is carried out while circulating the suspension in a cyclic reactor while controlling the reaction temperature at usually 5 to 120 ° C., preferably 30 to 100 ° C., more preferably 35 to 95 ° C. . The reaction temperature can be controlled by flowing cold or hot water from line 5 through a jacket 6 attached around the annular reactor. In the first step, suspension polymerization is performed until the conversion of the polymerizable monomer becomes at least 90%. If the conversion of the polymerizable monomer in the first step is too low, it is difficult to obtain colored particles having a sufficiently high conversion when the process proceeds to the continuous polymerization step. If the conversion is too low, a large amount of unreacted polymerizable monomers will remain in the obtained colored particles, making it difficult to recover the colored particles as spherical particles and after the drying step. In the processing step, coalescence due to fusion of the particles occurs, and irregular shaped particles and coarse particles are easily generated. The conversion of the polymerizable monomer in the first step is preferably 95% or more, more preferably 98% or more, and most preferably 99% or more. The reaction time is a time required to reach a predetermined conversion, but is usually 1 hour or more, and often 2 hours or more after reaching a predetermined reaction temperature. In the first step, colored particles (polymer particles) having a conversion rate of the polymerizable monomer of 90% or more are produced by a batch polymerization method.

As a reactor, a tank-type reactor 2 shown in FIG.
1 can also be used. The suspension is charged into the tank-type reactor, and the suspension is stirred using the stirrer 23 to generate a swirling flow, thereby preventing scale from adhering to various parts in the tank and sedimentation of particles. The reaction temperature and conversion are the same as described above.
The reaction temperature can be controlled by flowing cold water or hot water through the jacket 29.

2. Second step The dispersion stabilizer such as the colloid of the poorly water-soluble metal compound used in the preparation of the suspension adheres to the surface of the fine droplets of the monomer composition, and the dispersion stability of the droplets Improve. After the suspension polymerization in the first step, the dispersion stabilizer remains attached to the surface of the produced polymer particles. When the second suspension (that is, a suspension in which fine droplets of the monomer composition are dispersed) is continuously added to the reaction system in such a state, and continuous polymerization is performed, a new suspension is obtained. The droplets containing the unreacted polymerizable monomer added to the polymer particles come into contact with the polymer particles that have already been formed, causing coalescence and separation, and as a result, the polymerized toner finally obtained is Particles that are deformed instead of spherical and that are enlarged and fine compared to the target particle size are also generated.
Therefore, according to this method, it is not possible to obtain a polymerization toner having a target particle size and a particle size distribution, and it is not possible to suppress the formation of scale during continuous polymerization.

In the second suspension preparation step (granulation step),
Even if a suspension is prepared by increasing the amount of the dispersion stabilizer, and continuous polymerization is performed using such a suspension, enlargement of the particle size and generation of fluffy particles are observed, and the target particle size is reduced. A polymerized toner having a diameter and a particle size distribution cannot be obtained. Further, even with this method, it is not possible to effectively prevent adhesion of scale and contamination in the reactor.

Therefore, in the present invention, an aqueous dispersion of a dispersion stabilizer is added into the reactor after the completion of the first step and before proceeding to the continuous polymerization step, so that the dispersion is stabilized in the reaction system (reaction slurry). Allow the agent to disperse freely. When an aqueous dispersion of a dispersion stabilizer such as a colloid of a poorly water-soluble metal compound is added to the reaction system containing the polymer particles formed in the first step, the dispersion stabilizer is already attached to the surface of the polymer particles. Therefore, it is presumed that the added dispersion stabilizer does not adhere to the surface of the polymer particles but is freely dispersed mainly in the reaction system.
When the second suspension is continuously added into the reaction system while maintaining the free dispersion state of the dispersion stabilizer, droplets containing the newly added unreacted polymerizable monomer are formed. ,
It can be effectively prevented from coming into contact with the polymer particles that have already been formed and causing coalescence or separation. as a result,
A polymerization toner having a target particle size and particle size distribution can be produced by a continuous polymerization method.

The aqueous dispersion of the dispersion stabilizer used in the second step is the same as the aqueous dispersion medium containing the dispersion stabilizer used when granulating fine droplets of the monomer composition. You may. When an aqueous dispersion of a dispersion stabilizer is added to the reaction system after the first step, it is necessary to extract the same amount of the reaction solution from the reaction system as the amount added. Therefore, it is desirable that the concentration of the dispersion stabilizer in the aqueous dispersion is increased to generally 0.1 to 20% by weight, preferably about 0.5 to 10% by weight, and the amount of the aqueous dispersion added is reduced. . As the dispersion stabilizer, a colloid of a poorly water-soluble metal compound is preferable, and a colloid of a poorly water-soluble metal hydroxide is more preferable. In the second step, the amount of the dispersion stabilizer in the reaction system is usually 0.1 to 10 times the initial weight of the dispersion stabilizer in the first suspension used in the first step. , Preferably 0.5 to 5
The dispersion stabilizer is added so as to maintain the ratio by a factor of 1, more preferably 1 to 3 times. When the addition amount of the dispersion stabilizer in the second step is too small, when the process proceeds to continuous polymerization, irregularly shaped particles, enlarged particles, fine particles, and the like are easily generated, and a spherical particle having a desired particle size and particle size distribution is obtained. It is difficult to obtain a polymerization toner of the formula (1). If the amount of the dispersion stabilizer is too large, the viscosity of the reaction system increases, and the dispersion stabilizing effect decreases. In addition, the cleaning process after the polymerization reaction requires time and labor.

In the second step, an aqueous dispersion of a dispersion stabilizer is added into the reactor after the first step. On a plant scale, the aqueous dispersion is preferably added continuously or intermittently during a continuous reaction. Before the continuous addition of the second suspension into the reactor, it is preferred that a predetermined amount of the dispersion stabilizer be present in the reaction system in a free dispersion state. In the annular reactor of FIG. 1, an aqueous dispersion of a dispersion stabilizer is added from a line 7 into the reactor. When the aqueous dispersion of the dispersion stabilizer is continuously added into the reactor,
It is desirable to provide the supply port near the supply port connected to the line 8 to which the second suspension is continuously added. FIG.
In the case of the tank type reactor shown in (1), an aqueous dispersion of a dispersion stabilizer is added from the supply port 32 into the reactor. Also in this tank reactor, when the aqueous dispersion of the dispersion stabilizer is continuously or intermittently added into the reactor, the second suspension is continuously supplied to the supply port connected to the line 22 for continuous addition. It is desirable to provide the supply port at a close position.

3. In the third step of the present invention, after the first step, in the second step, in the reactor, after adding the aqueous dispersion of the dispersion stabilizer, or while adding continuously or intermittently, as a third step, From the supply port of the reactor, a second suspension of fine droplets of the monomer composition suspended in an aqueous dispersion medium containing a dispersion stabilizer is continuously added, and a polymerization initiator is added. While the suspension polymerization is continued in the presence, a reaction solution having a conversion of the polymerizable monomer of at least 90% is continuously withdrawn from the outlet of the reactor. Usually, the reaction liquid is extracted in an amount corresponding to the total amount of the aqueous dispersion of the dispersion stabilizer and the addition amount of the second suspension. At a laboratory scale, after the aqueous dispersion of the dispersion stabilizer is added, a reaction liquid corresponding to the added amount may be extracted. This third step is a continuous polymerization step. As the second suspension, one having the same formulation as that of the first suspension is usually used. That is, the second suspension is a suspension in which the monomer composition is dispersed as fine droplets by the granulation step, and the particle size and the particle size distribution of the droplets are the first suspension. It is desirable to use the same as the suspension in order to obtain a polymerized toner having a uniform particle size and particle size distribution after the continuous polymerization step. If the temperature in the reaction system is reduced by adding the aqueous dispersion of the dispersion stabilizer in the second step before continuously charging the second suspension, the temperature is raised until the reaction temperature reaches a predetermined reaction temperature. It is preferred to warm.

In the case of using an annular reactor, as shown in FIG.
0 is introduced continuously into reactor 1 via line 8. On the other hand, an amount of the reaction solution corresponding to the amount of the second suspension is continuously withdrawn from the outlet of the reactor through the reaction solution withdrawing line 4. At this time, an amount of the reaction solution corresponding to the amount of the aqueous dispersion of the dispersion stabilizer is also extracted, and the concentration of the dispersion stabilizer in the reaction system is adjusted. The minute droplets of the monomer composition containing the unreacted polymerizable monomer newly charged undergo suspension polymerization while circulating in the annular reactor to form polymer particles (colored particles). Convert. The second suspension can be added at a low temperature (for example, normal temperature), but it is necessary to raise the temperature to, for example, 40 to 50 ° C. or the polymerization temperature immediately before the addition into the reactor. It is preferable to obtain Reaction conditions such as the flow rate of the suspension and the reaction temperature in the annular reactor are the same as in the first step. The annular reactor can produce a high-speed flow of the suspension, and the turbulent state contributes to prevention of fouling of the wall surface, and also has a high heat removal capability, so that the reaction speed can be increased. Moreover, annular reactors are relatively inexpensive.

When a tank type reactor is used, as shown in FIG. 2, a second suspension is continuously added from a storage tank 30 via a feed pump 31 to a line 22 through a feed pump 31. The second suspension may be added after the temperature is raised to the reaction temperature. In the reactor, the reaction is performed with stirring.
On the other hand, an amount of the reaction liquid corresponding to the total amount of the dispersion stabilizer dispersion liquid and the continuous addition amount of the second suspension was supplied from the bottom of the tank reactor 21 to the line 24 and the pump 25. The reaction solution can be easily sent to the next step if the reaction solution is extracted to the storage tank 27 via the line 26.

In the continuous polymerization step, colored particles having a conversion of the polymerizable monomer of at least 90% are continuously extracted by adjusting the continuous addition amount of the second suspension. If the conversion in the third step is too low, a large amount of unreacted polymerizable monomer will remain in the obtained colored particles, and it will be difficult to collect the colored particles as spherical particles. In a post-treatment step such as a drying step, coalescence due to fusion of the particles occurs, and irregular shaped particles and coarse particles are easily generated. The conversion in the third step is preferably 93% or more,
It is more preferably at least 95%, particularly preferably at least 97%. This conversion can be increased to 98% or more, and even to 99% or more, but for that purpose, it is necessary to reduce the continuous addition amount of the second suspension and prolong the residence time. If the productivity is reduced due to a sufficiently long residence time, the reaction liquid extracted from the outlet of the reactor is introduced into another reactor, where it is suspended by a batch polymerization method or a continuous polymerization method. The polymerization can be continued to increase the conversion.

In the continuous polymerization step, the residence time of the reaction solution in the reactor varies depending on the continuous addition amount of the second suspension. The second suspension is added to the reactor usually in 0.5 to 5 hours, preferably 1 to 3 hours, in such an amount that the whole amount of the reaction solution in the reactor is replaced by the newly added suspension. It is desirable to add them continuously. According to the production method of the present invention, continuous polymerization can be stably performed in a substantially steady state. In the production method of the present invention, an aqueous dispersion of the dispersion stabilizer is added to adjust the dispersion so that the free dispersion state of the dispersion stabilizer in the reaction system is maintained.

According to the continuous polymerization method of the present invention, a large amount of suspension far exceeding the capacity of the reactor is suspended by continuously adding the suspension and continuously withdrawing the reaction solution. It can be subjected to turbid polymerization. Therefore, the size of the reactor can be reduced. Moreover, since the suspension can be circulated in the reactor, it is possible to suppress the adhesion of dirt on the wall surface and the like and the generation of scale. According to the continuous polymerization method of the present invention, the polymerization toner can be obtained as spherical particles, and the particle size and the particle size distribution can be obtained almost as designed. The reaction liquid extracted from the reactor by continuous polymerization is subjected to treatment such as acid washing, filtration, dehydration, water washing, and drying to recover a polymerization toner.

Additional Step In the production method of the present invention, an additional step can be arranged after the continuous polymerization step. Additional steps include:
For example, a step of introducing the reaction solution to the second reactor and continuing the suspension polymerization to increase the conversion rate, and reducing the concentration of the unreacted polymerizable monomer in the colored particles, the reaction solution Into the second reactor, further adding a polymerizable monomer or a polymerizable monomer composition for shell formation, and performing suspension polymerization in the presence of a polymerization initiator to form a core-shell structure. There is a step of obtaining a polymerization toner.

1. Step of increasing the conversion rate The reaction liquid extracted from the reaction vessel in the continuous polymerization step may not have a sufficiently high conversion rate. 90 conversion
Although it is possible to obtain spherical colored particles at a low level of about 97%, it is preferable to sufficiently increase the conversion by an additional step in order to increase the yield. Also, if unreacted polymerizable monomer remains in the colored particles, not only the monomer odor remains in the polymerized toner, but also the shape of the colored particles is deformed in post-processing steps such as washing, filtration, and drying. It becomes easily deformed and bloated, for example, by coalescence or coalescence. Therefore, the reaction liquid extracted from the reaction vessel in the continuous polymerization step, when the conversion is low, is introduced into the second reactor,
By continuing the suspension polymerization reaction, the conversion is increased to preferably 98% or more, more preferably 99% or more, and the concentration of the residual monomer in the colored particles is preferably 2% by weight or less, more preferably Is desirably reduced to 1.5% by weight or less, particularly preferably 1% by weight or less. By arranging such an additional step after the continuous polymerization step, a spherically polymerized toner can be easily obtained.

The second reactor may be a ring-type reactor as shown in FIG. 1 or a tank-type reactor as shown in FIG. Therefore, when two reactors are connected in series, the annular reactor-annular reactor, the annular reactor-tank reactor, the tank reactor-tank reactor, the tank reactor-annular There are combinations such as type reactors. If necessary, three or more reactors can be connected in series.
In the second reactor, batch polymerization or continuous polymerization is performed.
In the annular reactor shown in FIG. 1, line 4 is connected to the supply port of the second reactor. In the tank reactor shown in FIG. 2, the storage tank 27 is connected to the supply port of the second reactor by a line 28.

When the batch polymerization is carried out in the second reactor, the former continuous polymerization step can be regarded as the former polymerization step in a conventional method for producing a polymerization toner by batch polymerization from a different viewpoint. In the batch polymerization in the second reactor, since the suspension polymerization reaction has already progressed in the continuous polymerization step, inconvenience such as adhesion of scale is suppressed. In contrast, when batch polymerization is performed from the beginning in the same reactor,
After several batches of polymerization, scale deposition becomes visible.

2. In the present invention, the reaction liquid extracted from the reaction vessel in the continuous polymerization step is introduced into the second reactor, and then the polymerizable monomer or polymerizable monomer for forming the shell is formed. By adding a monomer composition obtained by mixing a monomer and water, an organic solvent, a charge control agent, and the like, and performing suspension polymerization by a batch polymerization method in the presence of a polymerization initiator, colored particles By forming a polymer layer covering the core made of the above, a polymerization toner having a core-shell structure can be manufactured. In the second reactor, the reaction solution extracted from the reaction vessel in the continuous polymerization step is further subjected to suspension polymerization to increase the conversion, and then the polymerizable monomer or polymerizable monomer composition for forming the shell is formed. Things can also be added. The combination and connection method of the reactors are the same as described above.

When a polymerization toner having a core-shell structure is produced, the fixing temperature is lowered by lowering the Tg of the polymer forming the core (colored particles) from the Tg of the polymer forming the shell. And storage stability (blocking resistance) can be enhanced. The level of Tg of each polymer forming the core and shell is relative.

When a polymerization toner having a core-shell structure is produced, Tg is usually 1 as a polymerizable monomer for forming a core.
It is preferable to use a polymerizable monomer capable of forming a polymer at 0 to 70 ° C, preferably 20 to 65 ° C, more preferably 30 to 60 ° C. The polymerizable monomer for forming a core can be used alone or in combination of two or more. If the polymerizable monomer for forming the core is capable of forming a polymer having a Tg exceeding 70 ° C., the fixing temperature of the polymerized toner increases, and it is difficult to cope with high-speed copying and printing. In addition, the OHP transparency of the image decreases. The Tg of the polymer is a calculated value (referred to as a calculated Tg) calculated according to the type and ratio of the polymerizable monomer used. More specifically, the Tg of the polymer can be calculated by the following equation.

100 / Tg = W ₁ / T ₁ + W ₂ / T ₂ +
_{W 3 / T 3 + ···· W} n / T n In the formula, Tg :( co) Glass transition temperature of the polymer (absolute _{temperature) W 1, W 2, W} 3 ····· W n ： Weight% of each monomer
(N is the number of monomers) T ₁ , T ₂ , T ₃ ... T _n : glass transition temperature (absolute temperature) of a homopolymer formed from each monomer (n is
Monomer number)

Examples of the polymerizable monomer for forming a shell include (meth) acrylates such as styrene, butyl acrylate, 2-ethylhexyl acrylate, ethylene, propylene, methyl methacrylate and methyl acrylate; amides such as acrylamide and methacrylamide; Vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; nitrogen-containing vinyl compounds such as 4-vinylpyridine; vinyl acetate, acrolein; and mixtures thereof. The difference in Tg between the polymer forming the core and the polymer forming the shell is preferably 10 ° C.
As described above, it is desirable to adjust the temperature to 20 ° C. or more. A charge control agent may be added to the polymerizable monomer for forming the shell. When a charge control agent is added, the amount used is generally 0.01 to 10 parts by weight, preferably 0.0 to 10 parts by weight, based on 100 parts by weight of the shell-forming monomer.
It is 3 to 5 parts by weight. If necessary, additives other than the charge control agent may be added to the shell-forming monomer.

The polymerizable monomer or monomer composition for forming a shell is subjected to suspension polymerization in the presence of colored particles (core) to form a polymer layer (shell) covering the core. At this time, the polymerizable monomer or monomer composition for forming the shell, using an ultrasonic emulsifier or the like, when added to the reaction system as droplets smaller than the number average particle diameter of the core and suspension polymerization. This is preferable because it easily migrates to the core surface to form a polymer layer.

When a water-soluble radical initiator is added as a polymerization initiator when adding the polymerizable monomer or monomer composition for forming a shell, a polymerization toner having a core-shell structure is easily formed. It is preferred. Examples of the water-soluble radical initiator include persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis-2-methyl-N-1,1
Azo initiators such as -bis (hydroxymethyl) -2-hydroxyethylpropioamide; combinations of an oil-soluble initiator such as cumene peroxide with a redox catalyst; and the like. The amount of the water-soluble radical initiator used is usually 0.001 to 1% by weight based on the aqueous medium.

In a polymerization toner having a core-shell structure, the weight ratio of the polymerizable monomer for forming a core to the polymerizable monomer for forming a shell is usually from 40/60 to 99.9 / 0.9.
1, preferably 60/40 to 99.7 / 0.3, more preferably 90/10 to 99.5 / 0.5. If the proportion of the polymerizable monomer for forming the shell is too small, the effect of improving the storage stability is small, and if it is too large, the effect of reducing the fixing temperature and improving the OHP permeability is small. The thickness of the shell is usually about 0.001 to 1 μm.

Polymerized Toner The volume average particle diameter (dv) of the polymerized toner of the present invention is generally 0.1 to 50 μm, preferably 0.5 to 30 μm, more preferably 1 to 20 μm, and particularly preferably 3 to 15 μm.
It is about. Volume average particle size (dv) and number average particle size (d
The particle size distribution represented by the ratio (dv / dp) to p) is usually 2.5 or less, preferably 2.0 or less, more preferably 1.8 or less. The lower limit of the particle size distribution is usually about 1.0. If the particle size distribution is too wide, the fixing temperature of the polymerized toner will vary, which tends to cause inconveniences such as fogging and toner filming.

The polymerization toner obtained by the production method of the present invention can be used as a one-component developer.
It can also be used as a two-component developer in combination with carrier particles. It is preferable that the polymerization method toner is a non-magnetic one-component developer by adding various additives (external additives) such as a fluidizing agent. The external additive is usually attached to the surface of the polymerization toner. Examples of the external additive include various inorganic particles and organic particles. Among these, silica particles and titanium oxide particles are preferable, and silica particles subjected to hydrophobic treatment are particularly preferable. In order to make the external additive adhere to the surface of the polymerization toner, the external additive and the polymerization toner are usually charged into a mixer such as a Henschel mixer and stirred and mixed.
The external additive not only plays a role of improving the fluidity of the polymerized toner, but also acts as an abrasive, and prevents the occurrence of a toner filming phenomenon on the photoconductor.

The image forming apparatus to which the polymerization method toner of the present invention is applied generally includes a photosensitive member, a unit for charging the surface of the photosensitive member, a unit for forming an electrostatic latent image on the surface of the photosensitive member, and a developer. Means for developing the electrostatic latent image on the photoreceptor surface by supplying a developer to form a toner image, and means for transferring the toner image from the photoreceptor surface to a transfer material.

[0062]

The present invention will be described more specifically with reference to the following examples and comparative examples. Parts and percentages are by weight unless otherwise specified. The measuring method of the physical properties is as follows. (1) Particle Size The particle size distribution represented by the volume average particle size (dv) of the particles and the ratio (dv / dp) of the volume average particle size to the number average particle size (dp) is determined by a Coulter counter (Coulter Co., Ltd.). Manufactured). The measurement conditions were as follows: aperture diameter: 100 μm
m, medium: Isoton II, concentration: 10%, number of measured particles:
50,000. (2) Conversion The conversion of the polymerizable monomer was determined by dissolving the polymer in benzene and quantifying the monomer by gas chromatography. (3) Residual concentration of unreacted polymerizable monomer The polymer was immersed in methanol, and the monomer in the filtrate was analyzed and quantified by gas chromatography to determine the residual concentration of unreacted monomer. I asked.

Example 1 Preparation of Monomer Composition A polymerizable monomer comprising 83 parts of styrene and 17 parts of n-butyl acrylate, carbon black (manufactured by Mitsubishi Chemical Corporation, #
25B) 7 parts, a charge control agent (Hodoya Chemical Co., Spiron Black TRH) 0.5 part, low molecular weight polypropylene (Sanyo Kasei Co., Ltd., 550P) 2 parts, t-dodecyl mercaptan 1.2 parts, and divinyl 0.6 parts of benzene
A monomer composition (mixture) was prepared by crushing and uniformly dispersing with a bead mill of a wet crusher.

Preparation of Aqueous Dispersion Medium Containing Dispersion Stabilizer In an aqueous solution in which 9.0 parts of magnesium chloride (water-soluble polyvalent metal salt) is dissolved in 215 parts of ion-exchanged water, 6 parts of ion-exchanged water are added.
An aqueous solution in which 5.5 parts of sodium hydroxide was dissolved in 5 parts was gradually added under stirring to prepare an aqueous dispersion medium containing a magnesium hydroxide colloid (a colloid of a poorly water-soluble metal hydroxide). When the particle size distribution of the formed colloid was measured with a Microtrac particle size distribution analyzer (manufactured by Nikkiso Co., Ltd.), the particle size was D ₅₀ (50% cumulative value of the number particle size distribution).
Was 0.37 μm, and D ₉₀ (90% cumulative value of the number particle size distribution) was 0.81 μm. In the measurement by this microtrack particle size distribution measuring device, the measurement range = 0.
The measurement was performed under conditions of 12 to 704 μm, measurement time = 30 seconds, and medium = ion-exchanged water.

Preparation of Suspension A mixed solution containing a polymerizable monomer is charged into the aqueous dispersion medium containing a colloid of magnesium hydroxide obtained above, and the mixture is stirred until the droplets are stabilized. As a polymerization initiator, 5 parts of t-butyl peroxy-2-ethylhexanoate (PB-O, manufactured by NOF Corporation) was added. Further, using an Ebara Milder manufactured by EBARA CORPORATION as a granulator, high-shear stirring was performed at a rotational speed of 15,000 rpm for 30 minutes to granulate fine droplets of the monomer composition.
The volume average particle size of the fine droplets was 6.9 μm. The aqueous dispersion medium containing these fine droplets was used as first and second suspensions.

As the batch polymerization reactor, the annular reactor shown in FIG. 1 was used. This annular reactor is a 22-liter reactor made up of a stainless steel tube with a jacket and a length of 3.5 m buffing the inside of 3 inches φ, and has a centrifugal pump and a stirrer equipped with a stirring blade. Thereby, the suspension in the tube can be circulated. After the inside of the annular reactor was replaced with nitrogen, the suspension prepared above was charged, and the flow rate in the tube was 2.0 m using a centrifugal pump and a stirrer.
The suspension was refluxed at / sec. The temperature of the suspension was raised to 90 ° C., and suspension polymerization was started in a batch system. When the batch polymerization was performed for 2 hours, the conversion of the polymerizable monomer became 99.5%, and a reaction solution containing colored particles having a volume average particle size of 7.3 μm and a particle size distribution of 1.31 was produced. .

Addition of Aqueous Dispersion of Dispersion Stabilizer In an aqueous solution obtained by dissolving 4.5 parts of magnesium chloride (water-soluble polyvalent metal salt) in 70 parts of ion-exchanged water, ion-exchanged water 38 was added.
An aqueous solution in which 2.7 parts of sodium hydroxide was dissolved was gradually added with stirring to prepare an aqueous dispersion containing a colloid of magnesium hydroxide (a colloid of a poorly water-soluble metal hydroxide). The particle size distribution of the resulting colloid was determined by Microtrac particle size distribution analyzer (manufactured by Nikkiso Co., Ltd.), particle size, (50% cumulative value of number particle diameter distribution) D ₅₀ is at 0.30 .mu.m, D ₉₀ (90% cumulative value of number particle size distribution)
Was 0.76 μm. This aqueous dispersion was added to the annular reactor in which the batch polymerization was performed for 2 hours, and approximately the same amount of colloid contained in the first suspension was supplemented. On the other hand, the same amount of the reaction solution as the amount of the aqueous dispersion containing the colloid was added. Next, the temperature of the reaction system was raised to 90 ° C. These operations correspond to the addition of the aqueous dispersion of the dispersion stabilizer into the reactor. In a production line on a plant scale, intermittent or continuous addition is performed, and extraction of the reaction solution is also performed continuously.

Continuous polymerization The second suspension was continuously added from the supply port to the annular reactor containing the reaction solution supplemented with the colloid of the dispersion stabilizer by using a reshpro pump, and was discharged. , An amount of the reaction solution corresponding to the added amount was continuously extracted. By continuing the continuous polymerization for 1 hour, the same amount of the second suspension as the initially added amount was added and withdrawn. Continuous polymerization 1
As a result of analyzing the reaction solution obtained after the elapse of time, the conversion was 95%, and the volume average particle size and the particle size distribution were almost the same as described above. No contamination was found on the annular reactor, and the condition was the same as before the start of the reaction.

Additional Step A reaction solution having a conversion of 95% obtained by continuous polymerization was introduced into a tank reactor, and suspension polymerization was continued for 2 hours. As a result, the conversion increased to 98% and unreacted Colored particles having a residual concentration of the polymerizable monomer of 1.8% by weight, a volume average particle size of 8.1 μm, and a particle size distribution of 1.34 were obtained. When the suspension polymerization was continued for a further 2 hours (4 hours in total), the conversion was 99%.
The residual concentration of the unreacted polymerizable monomer is 1.0% by weight, the volume average particle size is 7.6 μm, and the particle size distribution is 1.33.
Of colored particles were obtained. The particle size distribution of the colored particles was uniform both after the reaction for 2 hours and after the reaction for 4 hours. The colored particles are washed with acid by adding sulfuric acid to the reaction solution to adjust the pH to 4 or less.
5 ° C. for 10 minutes), and water is separated by filtration.
Add ion-exchanged water again to reslurry and wash with water, then repeat dehydration and water washing several times,
The solids were collected by filtration and dried overnight at 50 ° C. in a drier. Observation of the shape of the obtained colored particles by an electron microscope (SEM) photograph revealed that spherical particles were generated, and almost no agglomeration of particles and irregularly shaped particles were observed. Thus, a polymerized toner having a target particle size and a target particle size distribution was obtained.

Comparative Example 1 In Example 1, after performing suspension polymerization for 2 hours in the “batch polymerization” step, the “addition of aqueous dispersion of dispersion stabilizer” step was not performed.
A "continuous polymerization" step was performed. However, in the “continuous polymerization” step, by continuing the continuous polymerization for one hour,
Charge the same amount of the second suspension as the initial charge, and
I took it out. As a result of analyzing the reaction solution obtained one hour after continuous polymerization, the conversion was 96%. The obtained reaction liquid was washed with acid, filtered, washed with water and dried in the same manner as in Example 1 to collect colored particles. The volume average particle size of the colored particles was enlarged to about 20 μm, and the particle size distribution was also about 5. Observation using an electron micrograph revealed that, unlike at the time of batch polymerization, the particles were deformed, and the deformed particles were aggregated into clusters. In addition, dirt on the tube wall of the reactor was observed, making it difficult to extract liquid from an unused blow nozzle.

[Comparative Example 2] In Example 1, after performing suspension polymerization for 2 hours in the “batch polymerization” step, the “addition of aqueous dispersion of dispersion stabilizer” step was performed.
The "continuous polymerization" step was performed for one hour. Further, the reaction solution obtained by continuous polymerization was introduced into a tank reactor in the same manner as in Example 1, and the suspension polymerization was continued for 2 hours. As a result, the conversion rate increased to 98%, and further 2 hours. When the suspension polymerization was continued (for a total of 4 hours), the conversion increased to 99%. As described above, in Comparative Example 2, although the conversion was increased by an additional step as compared with Comparative Example 1, the particle size of the obtained colored particles was enlarged as in Comparative Example 1, and the particle size was large. The distribution was also found to be broad. The results of observation by electron micrographs showed that the aggregates and clusters of the particles were significantly reduced, but that the individual particles were present independently but enlarged together. In addition, a large number of feathery white flakes were found in the particles. Further, as in Comparative Example 1, contamination on the tube wall of the reactor was observed.

[Comparative Example 3] In Example 1, after performing suspension polymerization for 2 hours in the “batch polymerization” step, the “addition of aqueous dispersion of dispersion stabilizer” step was performed.
The "continuous polymerization" step was performed for one hour. However, in the continuous polymerization step, an aqueous dispersion of the dispersion stabilizer prepared in Example 1 was added to the suspension prepared in Example 1 as a second suspension to form a dispersion stabilizer (colloid). A suspension with a concentration of 50% increased was used. The continuous polymerization reaction was not stable because the reaction temperature fluctuated up and down. As a result of treating the obtained reaction solution in the same manner as described above to collect colored particles and analyzing the result, the volume average particle diameter was enlarged to 17 μm, and the particle diameter distribution was 2.8 and broad. . As a result of observation by an electron micrograph, aggregation of particles was observed. In addition, dirt on the tube wall of the reactor was observed.

[Embodiment 2] "Additional step" of Embodiment 1
After 4 hours, the polymerizable monomer for forming a shell is added to the reaction solution.
Of polymerized toner with core-shell structure
An experiment was performed. More specifically, methyl methacrylate
3 parts and 30 parts of water are finely dispersed by an ultrasonic emulsifier,
Aqueous systems containing fine droplets of polymerizable monomers for shell formation
A dispersion was obtained. The particle size of the droplet is 1%
Add 3% to sodium hexametaphosphate aqueous solution
Measured with a Microtrac particle size distribution analyzer.
Oh, D ₉₀Was 1.6 μm. A shell is added to the reaction solution.
Aqueous dispersion containing fine droplets of polymerizable monomer for forming
And a water-soluble radical polymerization initiator [2,2'-azobis
[2-Methyl-N- (2-hydroxyethyl) propio
And a solution obtained by dissolving 0.3 part in 30 parts of distilled water.
Was added and polymerization was carried out for 8 hours. After the completion of the polymerization reaction, the reaction solution
PH was adjusted to about 5 by adding sulfuric acid to the solution, and acid washing (25 ° C, 10
Min). Then, filtration, dehydration, and washing water shaking
Water washing, and then use a dryer at 45 ° C for one day.
After drying at night, a polymerized toner having a core-shell structure was obtained. This
Has a volume average particle size of 7.2 μm.
Was.

[0074]

According to the present invention, a polymerization toner having a desired particle size, a uniform particle size distribution, and a spherical shape is prepared by a continuous polymerization method while preventing contamination of the apparatus. A method of manufacturing is provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a cyclic reactor used in the production method of the present invention.

FIG. 2 is an explanatory view showing an example of a tank reactor used in the production method of the present invention.

[Explanation of symbols]

 1: Annular reactor 2: Circulation pump 3: Stirrer 4: Reaction liquid extraction line 5: Heating / cooling line 6: Jacket 7: Introduction line 8: Suspension feed line 9: Suspension storage tank 10 : Feed pump 21: Tank type reactor 22: Suspension feed line 23: Stirrer 24: Reaction liquid extraction line 25: Pump 26: Reaction liquid extraction line 27: Reaction liquid temporary storage tank 28: Reaction liquid Extraction line 29: Jacket 30: Suspension storage tank 31: Feed pump 32: Introduction line

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H005 AB06 4J011 AA04 AA08 AB08 BA01 BA08 BB04 BB10 DA03 JA02 JA03 JA04 JA05 JB07 JB08 JB12 JB24 JB26 JB29

Claims (2)

[Claims] 1. A polymerization initiator, after suspending a monomer composition containing at least a polymerizable monomer and a colorant as fine droplets in an aqueous dispersion medium containing a dispersion stabilizer. (1) In a method of producing a polymerization toner for producing colored particles by suspension polymerization in the presence of (1) a fine liquid of a monomer composition in an aqueous dispersion medium containing a dispersion stabilizer in a reactor. The first suspension in which the droplets are suspended is charged, and the suspension polymerization is carried out in the presence of a polymerization initiator until the conversion of the polymerizable monomer becomes at least 90%. After adding the aqueous dispersion of the dispersion stabilizer, or while adding continuously or intermittently, (3) in the reactor, the monomer composition in the aqueous dispersion medium containing the dispersion stabilizer When a second suspension of fine droplets is continuously added and suspension polymerization is continued in the presence of a polymerization initiator, In both cases, from (4) reactor,
A method for producing a polymerization toner, comprising continuously extracting a reaction solution having a conversion rate of a polymerizable monomer of at least 90%. 2. The method according to claim 1, wherein the dispersion stabilizer is a colloid of a poorly water-soluble metal compound.