JPH0151188B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing toner.

Conventionally, toners have generally been produced by melt-mixing colorants and other additives in a thermoplastic resin, uniformly dispersing the mixture, and then using a pulverizer and a classifier to produce toners having a desired particle size. Although this manufacturing method can produce fairly good toners, it has certain limitations. That is, the toner obtained using the pulverization method must have some brittleness so that the material is somewhat susceptible to pulverization. However, if the toner is too brittle, it will be pulverized too much, and in order to obtain a toner with an appropriate particle size distribution, it will be necessary to cut the toner into fine powder which is not economical, which will increase the cost. Furthermore, in some cases, the toner is further pulverized in the developing device of a copying machine. Further, when a low melting point material or a pressure fixable material is used to improve heat fixability, a fusion phenomenon occurs in a crushing device or a classification device, and continuous production may not be possible. Other requirements for the toner are that it has triboelectric properties suitable for development, that it forms an excellent image, that there is no change in performance when left unused, that it does not solidify (blocking, etc.), and that it has suitable heat or pressure fixation. Examples include having certain characteristics and not contaminating the surface of the photoreceptor.

Therefore, in order to overcome the drawbacks of the pulverization method, a method for producing toner using a suspension polymerization method was proposed. That is, since it does not involve any pulverization process, it does not need to be brittle, and because it is spherical, it has excellent fluidity, and therefore friction and electrification are uniform. Furthermore, by appropriately controlling polymerization, using a crosslinking agent, or incorporating some kind of additive, a toner with excellent heat or pressure fixing properties can be obtained.

However, it is technically difficult to carry out polymerization in a stable suspended system without coalescence, and to obtain fine polymer particles with a uniform particle size distribution through polymerization.

Therefore, when suspension polymerizing a polymerizable monomer system in water, a suspension stabilizer is used to prevent coalescence of polymer particles as the polymerization progresses. Generally, suspension stabilizers include poorly soluble, finely powdered inorganic compounds such as BaSO ₄ , CaSO ₄ , MgCO ₃ , BaCO ₃ , CaCO ₃ ,
Slightly soluble salts such as Ca ₃ (PO ₄ ) ₂ , inorganic polymers such as diatomaceous earth, silicic acid, clay, and talc, powders of metal oxides, and water-soluble polymers such as polyvinyl alcohol, gelatin, and starch. .

Furthermore, stirring also affects the stability of polymerization and particle size. High-speed stirring stabilizes polymerization, but the particles become smaller than necessary. On the other hand, if the mixture is stirred at low speed, it may gel and particles may not be obtained. Therefore, it is necessary to choose appropriate conditions.

However, even with these methods, the particle size that satisfies the toner, that is, the number average diameter of 10 μ
It is difficult to obtain fine particles of ~20μ.
This is because, in the end, there is no sufficient way to prevent union. Therefore, in the combination of a polymerizable monomer and an inorganic dispersant, the interface of the polymerizable monomer particles is cationically charged by the addition of a cationic polymerizable monomer or a poorly water-soluble organic amine compound; The inorganic dispersant is charged with an anion opposite to that of the polymerizable monomer particles, and therefore, the inorganic dispersant completely and uniformly covers the surface of the polymerizable monomer particles with strong ionic bonds, resulting in coalescence. A method has been proposed to prevent this and obtain fine particles with a number average diameter of about 10 to 20 μm. However, even with this method, the particle size cannot be said to be sufficiently satisfactory as a toner. This is because it is more preferable that the toner particle size distribution is narrower. In other words, when the particle size becomes uniform, the amount of charge on each particle becomes almost the same, and therefore a stable image can be obtained. The narrower the particle size distribution, the more stable the image, the better the reproducibility of fine lines, and the less fog there will be.

Furthermore, it is extremely difficult for the toner produced by this method to satisfy the conflicting properties of heat fixability, blocking property, and developability. In order to improve heat fixability, it is necessary to lower the melting temperature of the polymerized resin. For example, it is necessary to lower Tg (glass transition temperature). However, this is disadvantageous in terms of blocking properties. In order to improve blocking properties, at least
The Tg must be higher than the required blocking temperature, and the higher it is, the more advantageous it is. However, the toner produced by this method has cationic groups clustered on the particle surface, but the entire polymer is almost homogeneous, so in order to improve heat fixability, the molecular weight and Tg are lowered. The blocking property deteriorates, and this is also reflected in development, resulting in poor image quality. On the other hand, if the polymer is made to have a higher molecular weight or crosslinked in order to improve the blocking property, then the heat fixing property deteriorates, resulting in a vicious cycle.

Therefore, an object of the present invention is to provide a novel method for producing toner using such suspension polymerization.

Further, the present invention provides a method for producing a toner having an elbow-to-narrow particle size distribution.

Furthermore, the present invention provides a method for producing a toner having a low heat fixing temperature and good blocking properties.

Further, the present invention provides a method for producing a toner having good pressure fixing properties and good blocking properties.

Furthermore, the present invention provides a method for producing a toner for developing electrostatic images with good developability.

Furthermore, the present invention provides a toner for developing electrostatic images having excellent abrasion resistance and a method for producing the same.

That is, a system containing one or more types of polymerizable monomers, dyes and pigments, polymers, and other additives if necessary, is suspended in a dispersion medium in which an anionic dispersant is dispersed, This objective can be achieved by adding a cationic polymer or copolymer to the polymerizable monomer in the polymerization system.

Specifically, the present invention uses a cationic styrenic copolymer of styrene or a styrene derivative and a nitrogen-containing vinyl monomer to form a monomer system containing styrene or a styrene derivative as a polymerizable monomer. The heated monomer system containing the cationic styrenic copolymer is suspended in the heated dispersant system containing the anionic dispersant and polymerized. The present invention relates to a method for producing a toner, which comprises producing a toner having a pseudo capsule structure.

Without being bound by any theory, in the above method, when a cationic polymerizable monomer or a poorly water-soluble organic amine compound is added to the monomer system, these substances collect on the surface of the suspended particles and form monomers. It is thought that the particles are slightly distributed from the mass system into the dispersion medium system, and the interface between the particles and the dispersion medium becomes uncertain, which makes the suspended particles a little unstable, so that the particle size distribution cannot be said to be very narrow. . On the other hand, as in the present invention, a cationic styrene copolymer of styrene or a styrene derivative and a nitrogen-containing vinyl monomer is used as the cationic polymer, and the cationic styrene copolymer is replaced with styrene. Alternatively, when dissolved in a monomer system containing a styrene derivative and suspended in a dispersion medium system containing an anionic dispersant, the cationic styrenic copolymer collected on the surface of the suspended particles is dissolved in the monomer system (i.e. ,
(monomer system) into the dispersion medium system. This is because it has a high molecular weight. Therefore, the interface between the suspended particles becomes firm and stable, making it easier for the particle sizes to be uniform.

Furthermore, since the cationic copolymer gathers on the surface of the suspended particles, it takes on a kind of shell-like form, and the resulting particles become pseudo-capsules.
That is, irrespective of the initial polymerization of the polymerizable monomer, a resin having a desired degree of polymerization can be used as the cationic copolymer for the shell. Therefore,
In the present invention, when toner particles having a pseudo-capsule structure are produced, the interior is polymerized to have a relatively low molecular weight and excellent heat or pressure fixing properties, and the cationic copolymer in the shell is polymerized. For the combination, a resin having a relatively high molecular weight and excellent blocking properties, developability, and abrasion resistance can be used. Preferably, the cationic styrenic copolymer has a weight average molecular weight of 50,000 to 150,000, as shown in the examples below.

Examples of the cationic styrenic copolymer used in the present invention include dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, N-n-poxyacrylamide, trimethylammonium chloride, diacetone acrylamide, acrylamide, N-
The combination of nitrogen-containing monomers such as vinylcarbazole, vinylpyridine, 2-vinylimidazole, 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride, or those obtained by quaternizing nitrogen with the following styrene or styrene derivatives. A cationic styrenic copolymer is exemplified.

Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4- Dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n
- Styrene and derivatives thereof such as hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene.

Examples of the polymerizable monomers used in the present invention include the following, and one or more of these may be used. Further, one or more of these polymers may be contained in the polymerizable monomer.

Styrene, O-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4- Dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n
- Styrene and derivatives thereof such as hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene.

Examples of vinyl monomers include ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; vinyl acetate, and propionic acid. Vinyl, vinyl esters such as vinyl benzoate and vinyl butyrate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n methacrylate
-methylene aliphatic monomers such as butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, -2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. Carboxylic acid esters; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic acid 2 -chloroethyl, phenyl acrylate, methyl α-chloroacrylate; vinyl methyl ether,
Vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; Examples include N-vinyl compounds; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

Polymerization initiators used in the present invention include oxycarbonate, kyumene hydroperoxide,
2,4-dichlorylbenzoyl peroxide,
Lauroyl peroxide and the like can be used.

In the present invention, a crosslinking agent may be used to form a crosslinked polymer. For example, divinylbenzene, divinylnaphthalene and derivatives thereof, diethylene glycol methacrylate, triethylene glycol methacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, etc., 1,2-propylene glycol, 1,3 - A general crosslinking agent such as butanediol can be used as appropriate.

As the dispersant that can be used in the present invention, known anionic dispersants can be used. Examples include water-soluble polymers such as polyvinyl alcohol, partially saponified polyvinyl alcohol, and other vinyl alcohol copolymers, and finely powdered inorganic compounds such as colloidal silica, such as Aerosil 200 or 300.

Generally known dyes and pigments can be used in the present invention. Furthermore, carbon black and magnetic materials can also be used. In particular, magnetic materials should be surface-treated.

Further, in the present invention, a poorly water-soluble organic amine compound may be added to the monomer system.

In the suspension method, a monomer system in which a polymerization initiator, a cationic polymer or copolymer thereof, monomers, additives, dyes and pigments, crosslinking agents, etc. are uniformly dissolved or dispersed is mixed with a suspension stabilizer. It is dispersed in the contained dispersed phase, that is, the continuous phase, using a conventional stirrer, homomixer, homogenizer, etc. Preferably the monomer droplets are of the desired toner particle size, generally
The stirring speed and time may be adjusted so that the particles have a size of 30 μm or less, and thereafter stirring may be carried out to such an extent that sedimentation of the particles is prevented so that this state is substantially maintained by the action of the dispersion stabilizer.

Polymerization is carried out by setting the polymerization temperature appropriately. After the reaction is completed, the toner particles produced are recovered by a suitable method such as washing, filtering, decantation, centrifugation, etc., and dried.

All known methods can be used to develop this toner. For example, two-component development methods such as cascade method, magnetic brush method, and microtoning method; one-component development methods containing magnetic materials such as conductive-component development method, insulating-component development method, and jumping development method; powder Examples include cloud method and fur brush method; non-magnetic one-component development method in which toner is held on a toner carrier by electrostatic force and transported to a developing section for development.

Example 1 Styrene monomer 200 g Styrene-dimethylaminoethyl methacrylate copolymer 10 g (monomer ratio 8:2, = 50000) Azobisisobutyronitrile 10 g Phthalocyanine blue 10 g The mixture was heated to about 60° C. and mixed for about 5 minutes in a vessel equipped with a shear mixer. At this time, the front was also 60
Add styrene to styrene monomer while heating to ℃.
Dissolve the dimethylaminoethyl methacrylate copolymer.

Separately, 4 g of Aerosil #200 was dispersed in 1000 c.c. of water, and the slurry was heated to 60° C. while being stirred by a TK homomixer and stirred at 4000 rpm for about 1 hour.
Thereafter, this mixed system was stirred with paddle blade stirring to complete the polymerization. Thereafter, the dispersant was removed, washed with water, and overdried to obtain a toner having a pseudo-capsule structure.

The obtained toner had a number average diameter of 9.05 μm, 17% of the particles were 6.35 μm or less in number distribution, and 20.2 μm in volume distribution.
This amounted to 1%. (Coulter counter,
Aperture 100μ) Also, when mixed with iron powder carrier EFV250/400 at a toner content of 10wt%, the triboelectric charge was measured and found to be +10.4μc/g. Apply this developer to the copier NP.
As a result of reversal development using a -5500 machine, a good image could be obtained, and stable and good images were obtained even after continuous image printing of 50,000 sheets. Furthermore, this toner
As a result of the 50°C blocking test, no blocking occurred even after more than one week.

Comparative example 1 Styrene monomer 200g Dimethylaminoethyl methacrylate monomer
2 g of azobisisobutyronitrile, 10 g of phthalocyanine blue, and 10 g of phthalocyanine blue were mixed and subjected to suspension polymerization in the same manner as in Example 1 to obtain a toner.

The obtained toner had a number average diameter of 9.3 μm, a number distribution of 23% of particles of 6.35 μm or less, and a volume distribution of 5% of particles of 20.2 μm or more. Furthermore, when the triboelectric charge was measured in the same manner as in Example 1, it was found to be about the same as +9.5 μc/g, but fogging occurred from about 5,000 sheets during continuous image printing, resulting in defects. Also, in a blocking test at 50°C, blocking occurred overnight.

Example 2 Styrene monomer 180g Butyl acrylate monomer 20g Styrene-diethylaminoethyl methacrylate copolymer 10g (monomer ratio 9:1, = 100000) Azobisisobutyronitrile 10g BL-250 (manufactured by Titan Industries) 60g ASA-30 (Mitsubishi (manufactured by Kasei) 1g A toner was obtained by suspension polymerization in the same manner as in Example 1.

The obtained toner had a number average diameter of 8.5 μm, a number distribution of 20% of particles of 6.35 μm or less, and a volume distribution of 0% of 20.2 μm or more. (Coulter counter, aperture 100μ) This toner was put into a copying machine PC-10, and when an image was printed, a good image was obtained. Furthermore, even after 2000 consecutive images, the images remained good.
In addition, this toner did not block eyelids for more than one week in a 50° C. blocking test.

Comparative Example 2 In Example 2, 1 g of diethylaminoethyl methacrylate monomer was used instead of the styrene-dimethylaminoethyl methacrylate copolymer.
A toner was obtained in the same manner.

The obtained toner had a number average diameter of 9.1 μm, a number distribution of 25% of particles of 6.35 μm or less, and a volume distribution of 5% of particles of 20.2 μm or more. When this toner was put into a PC-10 copying machine and an image was printed, the image was slightly fogged. I tried to do this continuously, but after about 1000 images, the fogging increased further and the images became worse. This toner caused blocking in 3 days in a blocking test at 50°C.

Example 3 Styrene monomer 200 g Copolymer of styrene and dimethylaminoethyl methacrylate with 5% quaternized product of benzyl chloride 10 g (9:1 monomer ratio, = 150000) Azobisisobutyronitrile 10 g Phthalocyanine green 10 g Polymerization and toner production were carried out in the same manner as in Example 1. The obtained toner had a number average diameter of 8.3 μm, a number distribution of 18% of particles of 6.35 μm or less, and a volume distribution of 0% of particles of 20.2 μm or more. (Coulter counter, aperture 100μ) This was imaged in the same manner as in Example 1.

The triboelectric charge was +12.1 μc/g, and the image was good. Continuous image output was stable up to 50,000 frames, with no fogging.

Also, there were no problems in the 50°C blocking test.

Comparative Example 3 A toner was obtained by polymerizing 200 g of styrene monomer, 1 g of a monomer obtained by quaternizing dimethylaminoethyl methacrylate to 5% with benzyl chloride, 10 g of azobisisobutyronitrile, and 10 g of phthalocyanine green in the same manner as in Example 3. The obtained toner had a number average diameter of 9.0 μm and a number distribution.
The volume distribution was 21% below 6.35 μm, and 6% above 20.2 μm. Furthermore, image printing was performed in the same manner as in Example 3. The triboelectric charge was +11.0 .mu.c/g, and after 10,000 sheets of continuous image output, there was slight fogging, and after 20,000 sheets, the images became defective. Also, a blocking test was conducted at 50°C, but blocking occurred after 3 days.

Example 4 Styrene monomer 200g Styrene-dimethylaminoethyl methacrylate copolymer 10g (monomer ratio 8.5:1.5, = 150000) V-65 (manufactured by Wako Pure Chemical Industries) 10g Phthalocyanine blue 10g Divinylbenzene 1.0g Same as Example 1 The toner was created using the following method.

The obtained toner had a number average diameter of 8.7 μm, a number distribution of 17% of particles of 6.35 μm or less, and a volume distribution of 1% of particles of 20.0 μm or more. (Coulter counter 100μ aperture) This is held on the toner carrier by electrostatic force and transported to the developing section to be developed. Images were created using a method of developing toner that does not contain bodies. As a result, a good image was obtained. Also, continuous image output was performed, and stable images were obtained up to 20,000 images. Further, this toner had no problem with blocking properties at 50°C, was well fixed in a silicone oil coating system of a fixing device at 160°C, and had no offset.

Comparative Example 4 The styrene-dimethylaminoethyl methacrylate copolymer of Example 4 was changed to 1.5 g of dimethylaminoethyl methacrylate and polymerized in the same manner to obtain a toner.

This toner has a number average diameter of 9.2μm and a number distribution.
22% are 6.35μm or less, 4 are 202μm or more in volume distribution
It was %. This was developed in the same manner as in Example 4,
I made an image. As a result, although the images were good, some fogging occurred after 5,000 consecutive images, the image quality also deteriorated, and the reproducibility of fine lines became poor. Furthermore, this toner blocked when left overnight at 50°C, and although it fixed in a fixing device coated with oil at 160°C, offset was a problem.

Claims (1)

[Claims] 1. A cationic styrenic copolymer of styrene or a styrene derivative and a nitrogen-containing vinyl monomer is dissolved in a monomer system containing styrene or a styrene derivative as a polymerizable monomer. The heated monomer system in which the cationic styrenic copolymer is dissolved is suspended in the heated dispersion medium system containing the anionic dispersant and polymerized to form a pseudo-monomer. 1. A method for producing a toner, comprising producing a toner having a capsule structure. 2. The method for producing a toner according to claim 1, wherein the cationic styrenic copolymer has a weight average molecular weight of 50,000 to 150,000. 3. The method for producing a toner according to claim 1 or 2, wherein the anionic dispersant is colloidal silica. 4. The method for producing a toner according to any one of claims 1 to 3, wherein the monomer system contains a crosslinking agent.