JPS6057855A - Production of toner for developing electrostatic charge image - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a toner for developing an electrostatic image, and more particularly, to an improvement in a method for producing a toner for developing an electrostatic image by a suspension polymerization method.

Conventionally, toner used for developing electrostatic images is generally made by melt-mixing a colorant and a low-temperature machining of the colorant in a thermoplastic resin.
After uniformly dispersing, the solidified material is pulverized into 1 classification to produce colored fine particles of desired particle size.
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That is, the toner obtained using the pulverization method must have some brittleness so that the material is somewhat susceptible to pulverization. However, things that are too fragile
After being too finely powdered, in order to obtain toner with an appropriate particle size distribution, it is necessary to cut the fine powder by 10%.
This results in increased costs. Furthermore, in the developing device of a copying machine, the toner is sometimes further pulverized. In addition, if a low melting point material is used to improve heat fixing properties or a pressure fixing material is used, a crushing device,
Alternatively, a fusion phenomenon may occur in the 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 must be able to withstand considerable heat. having t-h pressure fixing characteristics;
For example, the I/X should not contaminate the surface of the photoreceptor. Particularly in fusing, the offset phenomenon in which toner adheres to the fusing roller and is retransferred onto the next copy paper has always been a problem, and to prevent this, it is necessary to apply silicone oil to the fusing roller. It has been practiced to apply such a release agent. However, in recent years, a method has become common in which a polyolefin such as polypropylene or polyethylene is contained in the I-chi to prevent offset without applying a release agent to the fixing roller.

However, this method has problems in that the fixing roller itself does not have a sufficient effect in preventing offset, so an auxiliary fixing roller cleaning device is required, and large quantities of copies cannot be made without maintenance.

Therefore, attempts were made to add a larger amount of polyolefin or to use a polyolefin with a lower melting point, but this resulted in problems such as fusion in the crusher or classifier, or blocking due to the exposure of the low melting point polyolefin on the toner surface. This resulted in problems such as poor fluidity and significantly reduced developability.

In order to overcome these drawbacks of the pulverization method, a method for producing toner as it is by suspension polymerization has been proposed, that is, a method for producing toner by suspension polymerization. This method does not involve any crushing process, so the toner does not need to be brittle, and the resulting toner has a spherical shape, so it has excellent fluidity and has various advantages such as uniform triboelectric charging. is obtained.

However, it is not necessarily technically easy to carry out polymerization in a stable suspended system without coalescence, and to obtain fine polymer particles having 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.

Suspension stabilizers used for this purpose generally include poorly soluble finely powdered inorganic compounds such as BaSO4,
CaSO4, Mgco, , Ba(03, CaCO3
, Ca(PO4)2; S-type polymers such as diatomaceous earth, talc, silicic acid, and clay; powders of metal oxides, and water-soluble polymers such as polyvinyl alcohol, seratin, 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, various studies have been made to select appropriate stirring conditions.

However, even with these methods, it is difficult to obtain fine particles with a particle size that is satisfactory as a toner, that is, a number average diameter of about 10 to 20. Ultimately, this is because there are insufficient methods to prevent the coalescence of suspended particles. Therefore,
In the combination of polymerizable monomer and inorganic dispersant,
By adding a cationic polymerizable monomer or a poorly water-soluble organic amine compound, the interface of the polymerizable monomer particles is cationically charged, while as an inorganic dispersant, the polymerizable monomer particles are charged with an opposite anionic charge. As a result, the inorganic dispersant completely and uniformly covers the surface of the polymerizable monomer particles through strong ionic bonds and prevents coalescence, resulting in a number average diameter of about 10 to 20 #L. A method for obtaining fine particles has been proposed.

However, even with this method, a toner with a sufficiently narrow particle size distribution cannot be obtained. 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.

Although not bound by theory, in the above method, if a cationic polymerizable monomer or a poorly water-soluble organic amine compound is added to the monomer system, these substances will collect on the surface of the suspended particles. It is thought that the particle size distribution will not be sufficiently narrow because the particles will be slightly distributed from the monomer system into the dispersion medium system and the interface between the particles and the dispersion medium will become uncertain, making the suspended particles a little unstable. It will be done.

Furthermore, it is difficult for the toner produced by this method to satisfy contradictory properties such as offset properties, fixing properties, blocking properties, and developability. Toner using this method
Although cationic groups are gathered on the particle surface, the whole is a nearly homogeneous aggregate, so in order to improve heat fixability, reducing the molecular weight and lowering the Tg (glass transition point) will improve the blocking property. Unfortunately, this will also be reflected in the development process, 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, one or more types of polymerizable monomers,
If necessary, a system containing dyes and pigments, polymers, and other additives is suspended in a dispersion medium in which an anionic dispersant is dispersed, and in a system in which polymerization is carried out, a cationic polymer is added to the polymerizable monomer. A method has been proposed in which polymerization is carried out by incorporating

By incorporating the cationic polymer into the monomer system, the cationic polymer collected on the surface of the suspended particles will not be completely distributed from the monomer system into the dispersion medium system. do not have. This is because the cationic polymer has already been made to have 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. In particular, the cationic polymer gathers on the surface of the suspended particles, forming 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 polymer or copolymer for the shell. Therefore, the interior is polymerized to have a relatively low molecular weight with excellent fixing properties, and the cationic polymer or copolymer in the shell has a relatively high molecular weight and has good blocking properties, developability, and abrasion resistance. Excellent resins can be used.

As described above, it can be seen that the addition of a cationic polymer monomer is particularly important in this suspension polymerization method. However, from the perspective of dispersibility only, there are various resins that can be used as cationic polymers.
In particular, it is very difficult to obtain toner with excellent properties. That is, such cationic polymers are generally wood-philic or hygroscopic, and since these polymers are exposed on the surface of the toner, they have a great effect on the charging properties. Furthermore, if a polymer with a low Tg is used, blocking will occur, resulting in clumping in an environment of, for example, 50°C.

Furthermore, during suspension polymerization, the cationic polymer also serves to determine the size distribution of the particles, so it must have an appropriate degree of cationicity.

However, the characteristics required of toner are diverse.
The toner obtained by the above method is also not necessarily satisfactory. For example, fusing characteristics include fusing temperature, offset phenomenon that stains the fusing roller, etc., and the resulting clinging of copy paper to the fusing roller; anti-blocking property that prevents toner from agglomerating during long-term storage, etc. It is still difficult to say that we are satisfied with this. In particular, the low fixing temperature and blocking resistance are
In general, these properties are contradictory, and it is extremely difficult to improve the performance of the other at the same time. Furthermore, since the toner particles produced by the suspension polymerization method are spherical, the surface area is small, and therefore the heat absorption area is also small, which is a disadvantageous factor for thermal fixing.

In view of the problems of the prior art described above, the main object of the present invention is to comprehensively improve the properties required for toner, such as fixing properties, anti-offset properties, anti-blocking properties, fluidity, and developability. An object of the present invention is to provide a method for producing a toner for developing an electrostatic image.

As a result of research for the above-mentioned purpose, the present inventors have found that a polymerizable mixture containing a cross-linking agent, a mold release agent, and a cationic polymer in a specific monomer system in a specific ratio is subjected to suspension polymerization. It has been found that a toner with comprehensively improved characteristics can be obtained by this method.

The method for producing the electrostatic image developing toner of the present invention is as follows.

This is based on such knowledge, and more specifically, monomer system 1 consisting of 70 to 80% by weight of styrene monomer and 20 to 30% by weight of 2-ethylhexyl methacrylate.
0.00 parts by weight, 0.5 to 4 parts of a bifunctional crosslinking agent, 2 to 5 parts of a mold release agent, 2 to 15 parts of a cationic polymer, and a coloring agent, were subjected to suspension polymerization. It is characterized by:

The present invention will be explained in more detail below. In the following description, "r%" and "parts" expressing quantitative ratios are based on weight unless otherwise specified.

The monomer system used in the present invention is styrene monomer 70-8
0% and 2-ethylhexyl methacrylate 20-30%
It consists of

As the styrene monomer, styrene itself is preferably used, and 40% or less of the styrene monomer is α-methylstyrene, m-methylstyrene, P-methylstyrene, P-methoxystyrene, P-fecolstyrene, P -Chlorstyrene, 3,4-dichlorostyrene, p-ethylmethylenef. 2.4-Dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene tP-n-hexylstyrene L/7. Styrenic monomer mixtures substituted with styrene derivatives such as P-H-dimethylstyrene, P-·n-nonylstyrene, p-n-decylstyrene, and p-n-dodecylstyrene may also be used.

In addition to the above-mentioned styrenic monomers, 2-ethylhexyl methacrylate is used in an amount of 20 to 30% based on the total amount thereof. This amount range is the most effective range for obtaining excellent fixing properties; if the amount of 2-ethylhexyl methacrylate is less than 20%, the resulting toner will have insufficient fixing properties, and if it is more than 30%. and a relatively high temperature (
For example, if it is left in an environment of 50°C or higher), it will no longer be stable.

The monomer system of the present invention comprises the above-mentioned styrenic monomer and 2-
It basically consists of ethylhexyl methacrylate, but up to 30 parts of other monomers copolymerizable with these two components, for example, based on 100 parts of the total amount of these two components, within a range that does not impair its basic characteristics. Quantities can be added.

Such monomers include, for example, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl oil; vinyl acetate, propion Vinyl esters such as vinyl acid and vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, inbutyl methacrylate, n-butyl methacrylate, dodecyl methacrylate, stearyl methacrylate, methacrylic acid α-methyl aliphatic monocarboxylic acid esters such as Fecol, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, acrylic n-butyl acid,
Dodecyl acrylate, 2-ethylhexyl acrylate,
stearyl acrylate, acrylic #2-chloroethyl,
Acrylic acid esters such as phenyl acrylate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Vinyl methyl ketone, vinyl hexyl ketone Me4-1 and IV-f
Vinyl ketones such as r I-so; N-
N-vinyl compounds such as vinylpyrrole, N-vinylrubazole, N-vinylindole, and N-vinylpyrrolidone; vinylnaphthalenes; vinyl monomers such as acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylateril, and acrylamide can be mentioned.

The difunctional crosslinking agent is used in an amount of 0.5 to 4 parts per 100 parts of the above monomer system. The bifunctional crosslinking agent is 0.5
If the amount is less than 4 parts, the resulting toner will have poor offset properties at high temperatures, and if it is used in excess of 4 parts, the fixing properties will be insufficient. The difunctional crosslinking agents used in the present invention include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol F200 dimethacrylate), 1.3 butylene glycol dimethacrylate, 1, 4 butylene glycol dimethacrylate, 1 ．．
6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylate-1, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2.2" bis(4-methacryloxyjetogysiphenyl)propane, 1, 6-hexane glycol diacrylate , 2,2°bis(4-acryloxyjethoxyphenyl)propane, divinylbenzene, etc. can be used.

The polymerizable mixture further contains 2 to 2 to 100 parts of monomer system.
Include 10 parts of mold release agent. If the # type agent is less than 2 parts, the effect of improving offset property is poor, and 1 of! If it is used in excess of Bt, the solubility with the monomer will deteriorate, making it difficult to obtain a homogeneous toner. Mold release agents that can be used are commercially available alone or in mixtures, and are generally paraffin wax, microcrystan wax, montan wax,
Ceresin wax, Osikelite, Carnauba wax,
Rice wax, shellac wax, Zazol wax, metal soap, amide wax, and lubricants are used.

The blending of cationic polymers is effective in improving the particle size distribution and charge control properties of the toner produced, and is used in the polymerizable mixture at a ratio of 2 to 15 parts per 100 parts of the monomer system. Ru. If the amount is less than 2 parts, the effect of addition is poor and sufficient charging properties cannot be obtained. If more than 15 parts are used, the viscosity of the system increases too much and the particle size distribution becomes wide, which may be undesirable.

The cationic polymers used in the present invention include dimethylamine ethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, N-n-butoxyacrylamide, trimethylammonium chloride dia7ton acrylamide, acrylamide, N-vinylcal/
Hesol, vinylpyridine, 2-vinylimidazole,
Homopolymers of N-containing monomers such as 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride, or combinations of these monomers with styrene and its derivatives, or acrylic and methacrylic monomers. It may also be used as a copolymer with a copolymerizable vinyl monomer as described above.

The polymerizable mixture may further contain 1 to 30 parts of other polymers, such as individual or copolymers of the above monomers, based on 100 parts of the polymerizable mixture, if necessary.

As the coloring agent, conventionally known carbon black, dyeing,
Pigments and magnetic powders can be used.

These colorants may be used in an amount of about 2 to 10 parts per 100 parts of the monomer system, and as magnetic powder when forming a magnetic toner, they are used in a proportion of about 20 to 100 parts.

In the polymerizable mixture, if necessary, a charge control agent,
A fluidity modifier may also be added. Examples of the charge control agent include metal-containing dyes and nigrosine, and examples of the fluidity modifier include colloidal silica and fatty acid metal salts.

Further, for the purpose of increasing the amount, fillers such as calcium carbonate and finely divided silica may be added in a range of 0.5 to 20%. Furthermore, in order to prevent mutual agglomeration of toner particles and improve their fluidity, a fluidity improver such as fine Teflon powder may be added. Waxy substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, Sasol wax, etc.
You can also add about %. In addition, these charge control agents,
The fluidity modifier is mixed with the toner particles obtained after polymerization (
It may also be used as an external additive.

The polymerizable mixture obtained by mixing the above components is dispersed in an aqueous phase, ie, a continuous phase, preferably containing an anionic dispersion stabilizer using a conventional stirrer, homomixer, homogenizer, etc., and subjected to hanging piJ polymerization. At the beginning of the polymerization, the stirring speed and time are preferably adjusted so that the monomer droplets have the desired toner particle size, generally less than 30 y, and thereafter depending on the action of the dispersion stabilizer In order to maintain this state, stirring may be performed to the extent that sedimentation of particles is prevented. The polymerization temperature is set at 50°C or higher, generally from 70 to 90°C. After the reaction is completed, the produced polymer particles are treated by an appropriate combination of washing, filtration, decantation, centrifugation, drying, etc., and then collected to obtain toner particles.

The obtained toner can be applied to all known electrostatic image development methods. For example, two-component development methods such as cascade method, magnetic brush method, and microtoning method; one-component development methods using magnetic toner such as conductive-component development method, insulating-component development method, and jumping development method; powder cloud method and fur brush method; used in non-magnetic component development methods in which toner is held on a toner carrier by electrostatic force and transported to a developing section for development.

As described above, according to the present invention, a crosslinking agent, a mold release agent, and a cationic polymer are blended in specific proportions into a monomer system consisting of a combination of styrene and 2-ethylhexyl methacrylate in specific proportions. By subjecting the resulting polymerizable mixture to suspension polymerization, a toner with comprehensively improved properties can be obtained.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Dissolve copolymer, paraffin wax, initiator, etc.
In a container equipped with a high shear force mixing device such as TK Homomixer (Tokushu Kika Kogyo type), the mixture was mixed for about 5 minutes while heating to about 60° C. to obtain a mixture having the above composition.

Separately, add 3.8g of Aeroseal #200 to 1000cc of water.
was dispersed, heated to approximately 60°C, and while stirring with a TK homomixer, the above monomer system was added, and further heated to 400°C.
Stir for approximately 1 hour at rpm.

Thereafter, the polymerization was completed while stirring this mixed system with a paddle stirring blade. After removing the dispersant, washing with water, filtering,
It was dried to obtain a toner.

The obtained toner had a number average diameter of 9.4 JLm as measured by a Coulter counter. This toner is NP-85
Images were produced using a 00 super copying machine (manufactured by Canon). As a result, the toner exhibited good developability and good fluidity, making it easy to supply the toner to the developing machine. Furthermore, NP-850
In the fixing machine of the 0 super copying machine, fixing is performed by changing the temperature, and the fixing temperature, the temperature range that causes the offset phenomenon,
I also examined the copy paper. As a result, it fixed at a temperature 20°C lower than conventional toners, offset development did not occur over a 30°C wider temperature range than conventional toners, and no curling occurred at all within the operating temperature range. .

Further, the toner obtained above showed the same fluidity as the initial state even after being left at 50'O for 11 weeks, and was found to have good blocking resistance.

Back J Exit 1ヱDissolve the copolymer, paraffin wax, initiator, etc.
In a container equipped with a high shear force mixing device such as a TK homomixer (manufactured by Tokushu Kika Kogyo), the mixture was mixed for about 5 minutes while heating to about 6°C to obtain a mixture having the above composition.

Separately, add 3.5 liters of Aerology Ay#200 to 1000cc of water.
The above monomer system was added to the mixture while stirring with a TK Pomo mixer, and the mixture was further stirred at 4000 rpm for about 1 hour.

Thereafter, the polymerization was completed while stirring this mixed system with a paddle stirring blade. After removing the dispersant, washing with water, filtering,
It was dried to obtain a toner.

The obtained toner had a number average diameter of 10.1 pm as measured by a Coulter counter. Use this toner on PC-10
Images were produced using a copying machine (Cannon acid). As a result, the toner exhibited good developability and good fluidity, making it easy to supply the toner to the developing machine. Further, fixing was carried out at different temperatures in the fixing machine of a PC-10 copying machine, and the fixing temperature, temperature range where offset phenomenon occurs, and copy paper curl were investigated. As a result, the fixing temperature is 25°C lower than that of conventional toners, and offset development is 40°C lower than that of conventional toners.
It did not occur over a wide temperature range, and no binding occurred at all over the operating temperature range.

Further, the toner obtained above showed the same fluidity as the initial state even after being left at 50° C. for one week, and was found to have good blocking resistance.

1 Styrene monomer 160g Dissolve the copolymer, paraffin wax, initiator, etc.
In a container equipped with a high shear force mixing device such as TK Homomixer (manufactured by Tokushu Kika Kogyo), the mixture was mixed for about 5 minutes while heating to about 60° C. to obtain a mixture having the above composition.

Separately, add 4.0g of Aeroseal #200 to 1000cc of water.
Dispersed, heated to approximately 60°C, and stirred with a TK homo mixer, the above-mentioned 1,000-year-old system was added, and further 400 or
The mixture was stirred for about 1 hour at m. Thereafter, the polymerization was completed while stirring this mixed system with a paddle stirring blade. Thereafter, the dispersant was removed, followed by washing with water, filtration, and drying to obtain a toner.

The obtained toner had a number average diameter of 8.8 pm as measured by a Coulter counter. This toner is NP-
Images were produced using a 8500 copying machine (Cannon acid). As a result, the toner exhibited good developability and good fluidity, making it easy to supply the toner to the developing machine. Roughly, fixing was carried out at different temperatures in the fixing machine of the NP-8500 copying machine, and the fixing temperature, the temperature range that causes the offset phenomenon, and the curl of the copy paper were investigated. As a result, approximately 2
It fixes at a temperature 0°C lower, and -offset development does not occur over a 25°C wider temperature range than conventional toners.
No burning occurred at all in the operating temperature range.

Further, the toner obtained above showed the same fluidity as the initial state even after being left at 50° C. for 11 weeks, and was found to have good blocking resistance.

Claims (1)

[Claims] 100 parts by weight of a monomer system consisting of 70 to 80% by weight of a styrene monomer and 20 to 30% by weight of 2-ethylhexyl methacrylate, 0.5 to 4 parts of a bifunctional crosslinking agent, and a mold release agent. 2 to 5 parts of a cationic polymer, 2 to 15 parts of a cationic polymer, and one colorant.