JP3009268B2 - Suspension polymerization toner and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension polymerization toner and a method for producing the same.

[0002]

2. Description of the Related Art In an example of electrophotography, an electrostatic latent image is formed on a photoreceptor by charging and exposure, and the electrostatic latent image is developed by a developer containing toner to form a toner image. Then, the toner image is transferred to a transfer material and fixed to form a visible image. On the other hand, toner remaining on the photoconductor without being transferred to the transfer material is cleaned by a cleaning member such as a blade. As a method for producing a toner used in such an electrophotographic method, conventionally, a coloring agent and other additives used as needed are added to a thermoplastic resin as a binder, and these are melt-kneaded and then pulverized. A so-called pulverization method for producing a toner by classification is known.

In this pulverization method, it is practically difficult to produce a toner having a small particle diameter having a volume average particle diameter of about 3 to 6 μm, for example, to prevent generation of fine powder due to brittle fracture of the resin. Usually, the volume average particle size is about 10 μm. However, such a toner having a large particle size cannot meet the recent demand for higher image quality, and thus has a problem in that fine line reproducibility is poor.

[0004] Under such circumstances, a method for producing a toner by a suspension polymerization method has recently been proposed. (1) JP-A-61-2354 and JP-A-2-22
JP 148046 describes the use of tricalcium phosphate as a dispersant in suspension polymerization. (2) JP-A-60-254159 describes that a water-soluble protein is used as a dispersant in suspension polymerization. (3) JP-A-59-161 and JP-A-1-24
No. 4471 describes the use of polyvinyl alcohol as a dispersant in suspension polymerization.

[0005]

However, in the above-mentioned conventional method, there is a problem that the obtained suspension polymerization toner has a high sphericity and the residual toner cannot be sufficiently cleaned in the cleaning step. .

[0006] The inventors of the present invention have conducted intensive studies and found that the removal of the dispersant during suspension polymerization causes the association of spherical fine particles, thereby obtaining deformed non-spherical toner particles. And completed the present invention. Therefore, a first object of the present invention is to provide a non-spherical suspension polymerization toner having good cleaning properties. A second object of the present invention is to provide a method for producing a suspension-polymerized toner capable of reliably producing a non-spherical suspension-polymerized toner having good cleaning properties.

[0007]

In order to achieve the above object, the suspension polymerization toner of the present invention is obtained by suspending a monomer composition containing a polymerizable monomer in an aqueous medium containing a dispersant. A suspension polymerization toner obtained by polymerization, in the suspension polymerization ,
Ratio of molecular weight of polymer particles to saturated molecular weight of polymer particles
When the degree of polymerization defined as is in the range of 40 to 80
Wherein the dispersant is removed and fine particles are associated . The method for producing a suspension-polymerized toner of the present invention is a method for producing a toner by suspension-polymerizing a monomer composition containing a polymerizable monomer in an aqueous medium containing a dispersant, In suspension polymerization , the saturated molecular weight of the polymer particles
Defined as the ratio of the molecular weight of the polymer particles to the polymer
The dispersant is removed at a time when the degree is in the range of 40 to 80.
Thereby associating fine particles . In addition, suspension polymerization is performed using a poorly water-soluble inorganic compound as a dispersant.
In the above, the amount of the polymer particles relative to the saturated molecular weight of the polymer particles
The degree of polymerization defined as the ratio of molecular weight is in the range of 40 to 80.
The dispersant is removed by dissolving the poorly water-soluble inorganic compound by adding an acid at a certain time .

Hereinafter, the present invention will be described specifically. [Suspension Polymerized Toner] The suspension polymerized toner of the present invention is a suspension polymerized toner obtained by suspension polymerizing a monomer composition containing a polymerizable monomer in an aqueous medium containing a dispersant. Thus, the dispersant is removed during the suspension polymerization. In the suspension polymerization, as shown in FIG. 1, the molecular weight of the polymer particles increases until the molecular weight becomes saturated with the lapse of the polymerization time.
Refers to a period when the degree of polymerization defined by the above is in the range of 40 to 80. However, in FIG. 1, the polymerization start point refers to a point in time when the suspension reaches a predetermined temperature at which the polymerization starts, and the polymerization end point refers to a point in time when the molecular weight of the polymer particles in the suspension is saturated. .

[0009]

(Equation 1)

By removing the dispersant during the suspension polymerization, the association of the fine particles is positively promoted in the subsequent suspension polymerization process, and the deformed non-spherical suspension polymerization toner is formed. can get. Therefore, according to the suspension polymerization toner, the residual toner on the photoconductor can be satisfactorily cleaned in the cleaning step.

The volume average particle diameter of the suspension polymerization toner is 3 to 6 μm.
m is preferable. According to the toner having such a small particle diameter, it is possible to form an image having high resolution and excellent reproducibility of fine lines. The volume average particle diameter of the suspension polymerization toner is
Laser diffraction particle size distribution analyzer "HELOS" (SY
MPATEC).

As the dispersant, a poorly water-soluble inorganic compound can be suitably used. When a poorly water-soluble inorganic compound is used, the poorly water-soluble inorganic compound can be removed by adding an acid. Examples of poorly water-soluble inorganic compounds include, for example, poorly water-soluble salts such as barium sulfate, calcium sulfate, barium carbonate, magnesium carbonate and calcium carbonate, orthophosphate, pyrophosphate and polyphosphate. Phosphates and the like. Preferred are secondary phosphates (M ₂ HPO ₄ ), tertiary phosphates (M
₃ PO ₄ ), pyrophosphate normal salt (M ₄ P ₂ O ₇ ), pyrophosphate acid salt (M ₂ H ₂ P ₂ O ₇ ), and tripolyphosphate (M ₅ P ₃ O ₁₀ ). Are metal salts such as calcium, magnesium, barium, iron, cadmium and strontium. Also, for example, an addition product Ca ₃ (PO ₄ ) _{2 of} tribasic sodium phosphate and calcium chloride
-Ca (OH) ₂ etc. can also be used. Particularly preferred is tricalcium phosphate [Ca ₃ (PO ₄ ) ₂ ].
It is.

As the polymerizable monomer, conventionally known ones can be used, and radically polymerizable ones are particularly preferable. One or a combination of two or more can be used so as to satisfy the thermal characteristics and electrostatic characteristics required for the toner. Specifically, a vinyl aromatic monomer,
Acrylic monomers, vinyl ester monomers, vinyl ether monomers, olefin monomers and the like can be suitably used.

As the vinyl aromatic monomer, for example,
Styrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n- Styrene-based monomers such as octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 2,4-dimethylstyrene, and 3,4-dichlorostyrene, and derivatives thereof. .

As the acrylic monomer, acrylic acid,
Methacrylic acid, methyl acrylate, ethyl acrylate,
Butyl acrylate, 2-ethylhexyl acrylate,
Cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, methacryl Dimethylaminoethyl acrylate, diethylaminoethyl methacrylate and the like.

Examples of the vinyl ester monomer include vinyl acetate, vinyl propionate, vinyl benzoate and the like. Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like. Examples of the olefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, and 4-methyl-
Monoolefin monomers such as 1-pentene and diolefin monomers such as butadiene, isoprene and chloroprene are exemplified.

Further, a crosslinking monomer may be added to improve the properties of the suspension-polymerized toner particles. As crosslinkable monomers, divinylbenzene, divinylnaphthalene,
Examples thereof include those having two or more unsaturated bonds such as divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

The toner contains additives such as a colorant, a fixability improver, and a charge control agent, if necessary. When these additives are used, when the suspension polymerization is carried out, It is mixed with a polymerizable monomer to form a monomer composition, and this monomer composition is added to an aqueous medium and used.

Conventionally known coloring agents can be used. If necessary, a surface treatment of a colorant to improve dispersibility may be used. Any colorant can be used as long as it can impart the color required for the toner. Specifically, inorganic or organic pigments are preferably used, and organic pigments are particularly preferably used. Examples of the black colorant include commercially available carbon black, carbon black grafted with a polymerizable monomer, and the like, carbon treated with a surface treating agent such as a silane coupling agent or an aluminum coupling agent. Black and the like.

The pigments for magenta or red include:
C. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16,
C. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57:
1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139,
C. I. Pigment red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I.
I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.

Examples of orange or yellow pigments include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12,
C. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I.
I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I.
Pigment Yellow 138 and the like.

The pigments for green or cyan include:
C. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3,
C. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

As the fixing property improver, conventionally known ones can be used. In particular, a polyolefin-based material is preferable, but not limited thereto. Also, 1
Species or a combination of two or more species may be used. Examples of the polyolefin-based fixability improver include low molecular weight polyethylene, low molecular weight polypropylene, acid-modified polyethylene, acid-modified polypropylene, oxidized polyethylene, oxidized polypropylene, such as paraffin wax, etc. And the like.

Examples of the charge control agent include metal complex dyes, nigrosine dyes, and ammonium compounds.

A fluidizing agent or the like may be further added to the suspension polymerization toner obtained as described above, if necessary, from the outside. As such a fluidizing agent, silica, titanium oxide, inorganic oxides such as aluminum oxide, inorganic nitride,
Carbides, organic fine particles and the like. These may be used in combination as appropriate.

[Production Method of Suspension-Polymerized Toner] In the production method of the suspension-polymerized toner of the present invention, a monomer composition containing a polymerizable monomer is subjected to suspension polymerization in an aqueous medium containing a dispersant. A method of producing a toner by removing the dispersant during the suspension polymerization to obtain fine particles.
A suspension polymerized toner is produced by associating.

In one example of the production example, a polymerizable monomer constituting a binder resin of a toner and an additive such as a coloring agent are added, and the mixture is sufficiently stirred by, for example, a sand mill or the like, and dispersed. A monomer composition is prepared. To this monomer composition, after adding a polymerization initiator if necessary, this is added to an aqueous medium containing a dispersant composed of, for example, a poorly water-soluble inorganic compound, and dispersed and suspended by a high-speed stirrer or the like. hand,
The polymerization reaction is allowed to proceed while maintaining a predetermined temperature condition. During suspension polymerization in which the degree of polymerization of the polymer particles is in the range of 40 to 80, an acid or the like is added to the suspension to decompose and remove the poorly water-soluble inorganic compound, and the polymerization reaction is further continued. A monomer composition suspended as fine oil droplets in an aqueous medium is
Polymerization and solidification occur during association, and non-spherical suspension-polymerized toner particles containing additives such as a colorant are obtained.

[0028] The polymerization initiator optionally used includes, for example, 2,2'-azobisisobutyronitrile,
2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile) Azobis-based polymerization initiators such as 1,1,1'-azobis (cyclohexane-1-carbonitrile), benzoyl peroxide, lauroyl peroxide, te
rt-butyl peroxy-2-ethylhexanoate,
Organic peroxides such as acetyl peroxide and tert-butyl perbenzoate are exemplified. The amount of the polymerization initiator used can be adjusted according to the required molecular weight, but is preferably in the range of 0.1 to 10% by weight, more preferably 1.5 to 7% by weight, based on the polymerizable monomer. Is preferable.

[0029]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these embodiments. In the following, “parts” means “parts by weight”. [Example 1] Monomer composition Polymerizable monomer 90 parts of styrene 10 parts of butyl methacrylate 5 parts of colorant carbon black 5 parts of fixing property polypropylene 5 parts of the above monomer composition was sufficiently mixed and homogenized by a sand grinder. Then, 1.8 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator.

Aqueous medium (A) 25.6 parts of trisodium phosphate dodecahydrate (Na ₃ PO ₄ .12H ₂ O) 0.04 part of sodium dodecylbenzenesulfonate (C ₁₂ H ₂₅ C ₆ H ₄ SO ₃₎ Na) 53.4 parts of water (H ₂ O) (B) 11.2 parts of calcium chloride (CaCl ₂ ) 102.0 parts of water (H ₂ O) The above (A) and (B) are mixed and poorly water-soluble. Inorganic compound [C
a ₃ (PO ₄ ) ₂ ] was prepared. The poorly water-soluble inorganic compound [Ca ₃ (PO ₄ ) ₂ ] is produced by a reaction represented by the following formula. 2Na ₃ PO ₄ + 3CaCl ₂ → Ca ₃ (PO ₄ ) ₂ + 6NaCl

[Preparation of Suspension] The above-mentioned monomer composition was charged into the above-mentioned aqueous medium, and suspended using a homomixer (manufactured by Tokushu Kika) to prepare a fine particle suspension.

[Preparation of Associated Particles] The polymerization was started at 70 ° C. in a nitrogen atmosphere while stirring the suspension at a low stirring speed. When the degree of polymerization of the polymer particles reached 40, hydrochloric acid (HCl) was added, and the pH in the system was set to 2 to continue the polymerization. The system under continuous polymerization was analyzed by ESCA (surface analysis) using an apparatus (model PHI560) manufactured by Perkin Elmer, and the poorly water-soluble inorganic compound [Ca ₃ (PO ₄ ) ₂ ] was converted to hydrochloric acid ( (HCl) was added, and it was confirmed that it was decomposed as shown by the following formula 2 and almost removed (dissolved). Since the reaction of the following formula 2 occurs under the condition that the pH of the suspension is less than 5, hydrochloric acid (HCl) may be added so that the pH of the suspension becomes less than 5.

[0033]

(Equation 2)

Five hours after the start of the polymerization, the molecular weight of the polymer particles was saturated, and the polymerization was terminated to obtain polymer particles.

[Post-treatment] The polymer particles were put into an aqueous hydrochloric acid solution (pH = 1), and the slightly remaining poorly water-soluble inorganic compound [Ca ₃ (PO ₄ ) ₂ ] was completely dissolved and removed. After washing with water, filtration and drying, a suspension polymerization toner was obtained.

With respect to the obtained suspension polymerization toner, the following items were evaluated. (1) The volume average particle size D ₅₀ above suspension polymerization toner, laser diffraction particle size distribution measuring apparatus using "SALD-1100" (manufactured by Shimadzu Corporation) to measure the volume average particle diameter D _50.

(2) Coefficient of variation Cv (standard deviation / D ₅₀ ) Using the volume average particle diameter D ₅₀ measured in the above (1), a coefficient of variation Cv (standard deviation / D ₅₀ ) was determined. The smaller the coefficient of variation Cv, the narrower the particle size distribution.

(3) Degree of Deformation N The amount of nitrogen (N ₂ ) adsorbed on the above suspension-polymerized toner by using a flow-type specific surface area automatic measurement apparatus “Flowsorb II 2300” (manufactured by Micromeritics). Is measured, a BET specific surface area is measured from this value, and a particle diameter D calculated assuming a spherical shape based on the BET specific surface area is
The seeking divided by the volume average particle diameter D ₅₀ (1), which was used as the degree N of the profiled. When it is a spherical particle,
N = 1, and N> 1 for non-spherical particles.

[Evaluation of actual printing] A developer was prepared using the above suspension polymerization toner, and a laser beam printer “DC80” was used.
28 "(manufactured by Konica Corporation) as an initial evaluation.
One cycle (charging, exposure, development, transfer, fixing, and cleaning) was carried out and a cleaning property was evaluated based on the presence or absence of toner remaining on the photoconductor after cleaning. The case where there was no residual toner was evaluated as ○, and the case where there was residual toner was evaluated as x. The above results are shown in Table 1 below.

Example 2 In Example 1, hydrochloric acid (H
A suspension polymerization toner was produced in the same manner as in Example 1 except that the timing of adding Cl) was the time when the degree of polymerization of the polymer particles reached 48, and evaluation was conducted in the same manner as in Example 1. The results are shown in Table 1 below.

Example 3 In Example 1, hydrochloric acid (H
The Cl) was changed to sulfate (H ₂ SO _4), sulfuric acid (H ₂
A suspension polymerization toner was manufactured in the same manner as in Example 1 except that the time when SO ₄ ) was added was a point in time when the degree of polymerization of the polymer particles reached 61, and evaluation was performed in the same manner as in Example 1. The results are shown in Table 1 below.

Example 4 In Example 1, hydrochloric acid (H
A suspension polymerization toner was produced in the same manner as in Example 1 except that the timing of adding Cl) was the time when the degree of polymerization of the polymer particles reached 72, and was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

Example 5 In Example 1, hydrochloric acid (H
Cl) to nitric acid (HNO ₃ ), and this nitric acid (HNO ₃ )
_A suspension polymerization toner was manufactured in the same manner as in Example 1 except that the time of adding ₃ ) was the time when the degree of polymerization of the polymer particles reached 80, and evaluation was performed in the same manner as in Example 1. The results are shown in Table 1 below.

Comparative Example 1 In Example 1, hydrochloric acid (H
A suspension polymerization toner was produced in the same manner as in Example 1 except that the timing of adding Cl) was the time when the degree of polymerization of the polymer particles was 0 (polymerization start time), and evaluated in the same manner as in Example 1. did. The results are shown in Table 1 below.

Comparative Example 2 In Example 1, hydrochloric acid (H
A suspension polymerization toner was produced in the same manner as in Example 1 except that the timing of adding Cl) was the time when the degree of polymerization of the polymer particles reached 35, and the evaluation was conducted in the same manner as in Example 1. The results are shown in Table 1 below.

Comparative Example 3 In Example 1, hydrochloric acid (H
A suspension polymerization toner was produced in the same manner as in Example 1 except that the timing of adding Cl) was the time when the degree of polymerization of the polymer particles reached 82, and evaluation was conducted in the same manner as in Example 1. The results are shown in Table 1 below.

Comparative Example 4 In Example 1, hydrochloric acid (H
A suspension polymerization toner was produced in the same manner as in Example 1 except that the timing of adding Cl) was the time when the degree of polymerization of the polymer particles reached 100 (at the end of polymerization). evaluated. The results are shown in Table 1 below.

[0048]

[Table 1]

As shown in Table 1, according to the embodiment of the present invention, a non-spherical suspension polymerization toner having good cleaning properties can be obtained. However, in Comparative Example 1, since hydrochloric acid was added at the start of the polymerization, the association of the suspension droplets became remarkably excessive, and the suspension state was disintegrated into a state of phase separation. Could not. In Comparative Example 2, a sufficient non-spherical suspension-polymerized toner could not be obtained because the associative force was weak even if the associative particles were obtained. Comparative Example 3
In Nos. 4 and 4, the association was insufficient because the timing of adding hydrochloric acid was too late, and the shape of the suspension polymerization toner was almost spherical.

[0050]

As described above in detail, according to the first aspect of the present invention, a non-spherical suspension polymerization toner having good cleaning properties can be obtained. According to the second aspect of the present invention,
A non-spherical suspension polymerization toner having good cleaning properties can be reliably produced.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the polymerization reaction time in suspension polymerization and the molecular weight of polymer particles.

Claims (3)

(57) [Claims] 1. A in an aqueous medium containing a dispersing agent, a suspension polymerization toner obtained by suspension polymerization of a monomer composition containing a polymerizable monomer, in suspension polymerization, the polymerized particles Saturation
Defined as the ratio of molecular weight of polymer particles to molecular weight
When the degree of polymerization is in the range of 40 to 80, the dispersant is removed.
A suspension-polymerized toner, wherein the fine particles have been removed and associated with each other . In wherein an aqueous medium containing a dispersing agent, a by suspension polymerization of a monomer composition containing a polymerizable monomer and a method for producing a toner, in the suspension polymerization, saturation of polymerized particles molecule
Weight, defined as the ratio of the molecular weight of the polymer particles to the weight
Remove the dispersant at a time when the strength is in the range of 40 to 80
A method for producing a suspension-polymerized toner, wherein the particles are associated with each other . 3. The method according to claim 2, wherein a poorly water-soluble inorganic compound is used as a dispersant , and
The ratio of the molecular weight of the polymer particles to the saturated molecular weight of the composite particles
Suspension polymerization, wherein the dispersant is removed by dissolving the poorly water-soluble inorganic compound by adding an acid at a time when the degree of polymerization defined as follows is in the range of 40 to 80. Manufacturing method of toner.