JPH0416860A - Toner for developing electrostatic latent image and production thereof - Google Patents

Abstract

PURPOSE:To obtain stronger uniform additive coatings on toner particles by keeping a mixed dispersion contg. the toner particles and an additive having smaller particle size than the toner particles at a temp. above the glass transition point of synthetic resin forming the toner particles, carrying out stirring and coating the toner particles with the additive. CONSTITUTION:Toner particles and an additive such as flowability rendering agent or an electrostatic charge controlling agent are dispersed and suspended in a solvent such as water under proper conditions with a surfactant, etc. The resulting dispersion is heated to a temp. above the glass transition point or softening point of synthetic resin forming the toner particles, moderate stirring is carried out and the surfaces of the toner particles are coated with the additive. The coated toner particles are dehydrated and dried. Uniform surface treatment of the toner with high accuracy is enabled.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to an electrostatic latent image developing toner and a toner for developing an electrostatic latent image in electrophotography or electrostatic recording. It relates to its manufacturing method.

(Prior Art) Methods for developing electrostatic latent images include (a) a one-component development method in which a thin layer of toner is formed on a conductive roller and developed by bringing it close to or in contact with the electrostatic latent image; (b) ) A two-component development method in which the toner is triboelectrified to a predetermined polarity by mixing and stirring with carrier particles having a particle size larger than the toner and developed by bringing the toner close to or in contact with the electrostatic latent image; A liquid developing method in which an electrostatic latent image is immersed in an insulating liquid in which fine toner particles are dispersed is generally known.

Incidentally, in the cases (a) to (b) above, that is, toner for dry development is generally manufactured as follows. The first method is a method called a kneading and pulverizing method or a melt mixing method. That is, a thermoplastic resin is used as a base material, and a coloring agent and, if necessary, a magnetic material powder, a tribostatic charge control agent,
After adding a release agent, etc., and heating, melting and kneading, it is cooled, crushed and classified to obtain toner particles with an average particle size of generally 8 to 20 μm, and hydrophobic to improve fluidity and chargeability. In this method, a desired toner for developing an electrostatic latent image is obtained by adding and mixing so-called external additives or surface treatment agents such as silica fine particles or titanium oxide fine particles, and coating the surface with the external additive.

The second means is, for example, Japanese Patent Publication No. Sho H-10231,
This is a suspension polymerization method disclosed in Japanese Patent Publication No. 47-518305. In this suspension polymerization method, fine monomer particles having a polymerizable unsaturated group, a colorant, and if necessary magnetic material powder, a triboelectric charge control agent, a mold release agent, etc. are mixed into a solvent such as water at an interface. Disperse and stir using an activator, etc., and
By performing polymerization and granulation in the presence of a polymerization initiator at a temperature of approximately 90°C to 90°C, toner particles of a predetermined size are obtained, which are then washed and dried to form a powder. In this method, a desired toner is obtained by adding and mixing external additives such as hydrophobic silica fine particles and titanium oxide fine particles to coat the surface in order to improve fluidity and chargeability.

If necessary, the particle size distribution is adjusted by classification either prior to addition and mixing of external additives or after coating with external additives.

(Problems to be Solved by the Invention) However, the above-mentioned conventional electrostatic latent image developing toner and its manufacturing method have the following problems. For example, in the field of liquid developers, recently there has been a development in which fine toner particles of about 0.5 to 2 μm (micrometers) are suspended in a petroleum-based insulating liquid, which is used for so-called transfer type copying. being researched. However, in this type of toner, the problem that the toner precipitates and aggregates in the developer during storage, making it difficult to redisperse, has not been sufficiently improved compared to the dry developing method. In other words, even if silica or the like is added to the toner to improve its dispersibility, when it is dispersed in a liquid, the toner separates and diffuses into the liquid, and does not exhibit the desired effect. As described above, the reality is that no surface treatment technology has been established for preventing the aggregation of toner for fine liquid developers.

On the other hand, the suspension polymerization method described above is seen as a promising toner production method in the future because it simplifies the process because it does not require kneading or pulverization, and is suitable for efficiently obtaining smaller toner particles. There is.

However, this toner manufacturing method is complicated in that it requires two steps: a wet process and a dry process, in which toner particles are formed in a wet process and external additives are added after drying.

In addition, in the toner manufacturing process using the above-mentioned suspension polymerization method, although the purpose is different from coating the toner surface, there are cases where silica powder is added at an early stage such as during monomer dispersion for the purpose of a dispersion aid. . However, in this case, silica powder etc. are incorporated into the monomer oil droplets during the polymerization granulation stage, and there is almost no exposed external additive on the surface of the final polymerized particles. . As a result, the surface of the toner is not coated with silica, and as described above, the actual situation is that external additives must be added again after drying.

In this case, it may be possible to add a large amount of silica from the beginning so that enough silica remains at the final stage of polymerization, but do not add so much silica that it remains until the end and covers the toner surface. If added, there is a problem in that the polymerization reaction and the formation of polymer particles (granulation) are significantly hindered. In this way, in conventional toner manufacturing methods, external additives are simply mixed mechanically in a dry powder state, so the added external additives are mainly attached to the toner by electrostatic force. Only. For this reason, during use (during development)
Another disadvantage is that external additives tend to separate from toner particles and adhere to carrier particles and photoreceptors. In other words, the detached external additives are often the main cause of problems in cleaning the photoreceptor and short-term deterioration of developing performance.

Further, problems caused by the detachment of the external additives also occur significantly in the dry development method. For example, in the component development method, the toner on the developing roller loses external additives such as silica, which play a role in releasability and fluidity between the developing roller and the toner, resulting in a rapid decrease in development sensitivity and separation. There is a problem in that triboelectric charging properties are impaired due to the influence of external additives, resulting in poor images.

In addition, as mentioned above, external additives basically have the disadvantage of being easily removed, so if the amount added is increased, they become even more likely to be removed and side effects become noticeable, so it is not possible to add the necessary and sufficient amount. However, it was difficult to completely coat the toner surface with external additives. Therefore, there remains the problem that there is a limit to its function as a release agent that prevents toner from agglomerating and solidifying when left to stand, as well as its ability to improve storage stability and fluidity.

Furthermore, in order to improve the storage stability of toner, it is necessary to select a resin with a high glass transition point as the main component of the toner. There were completely contradictory requirements, and it was difficult to achieve a satisfactory level of coordination. Also,
These problems become more pronounced as the toner particle size becomes smaller, and solving these problems is essential for the practical use of small-particle toners with excellent image quality.

In order to solve the above-mentioned problems, the present inventor researched various methods of adding external additives to toner, and found that fusing the external additive to the resin particles constituting the toner is effective in removing the additive from the toner particles. Based on the belief that this is effective in preventing the release of external additives, an attempt was made to mix and coat toner particles dispersed by wind in hot air with external additives. However, temperature control is difficult, and the toner particles may melt too much and fuse together, or external additives may get inside and cause the toner to malfunction.
Alternatively, the temperature was too low and did not fuse sufficiently, making it difficult to control the temperature uniformly and with high precision to ensure good coverage of the external additive, making it impossible to achieve the objective. Furthermore, it is difficult to produce toner particles with a particle size smaller than approximately 8 μm;
In particular, it is impossible to produce toner having a particle size of around 1 μm for use in liquid development using the pulverization method. Although this is possible by the suspension polymerization method, it is difficult to add external additives to such fine powder by the above-mentioned means, and therefore sufficient performance cannot be obtained.

The present invention has been made to solve the above problems,
Durability and fixation with stronger and more uniform external additive coating,
An object of the present invention is to provide a toner for developing an electrostatic latent image that has excellent storage stability and image quality, and an improved method for producing the toner by which the toner for developing an electrostatic latent image can be obtained in a package.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a toner particle body mainly composed of a synthetic resin and a toner particle body mainly composed of a synthetic resin, a metal oxide such as hydrophobic silica, titanium oxide, alumina, zinc stearate, etc. For the purpose of improving the fluidity and cohesiveness of fatty acid metal salts or fluororesins such as polyfluorinated ethylene, or improving the charging properties, external additives are added to water or other dispersions using surfactants. By dispersing under appropriate conditions, heating the dispersion above the glass transition point (or softening point) of the resin forming the toner particle body, and performing appropriate stirring, a uniform and strong coating is formed on the toner surface. It is based on knowledge of what is being done.

That is, in the above method, since the specific gravity of the toner and water is relatively similar, it is possible to maintain uniform dispersion of the electrostatic latent image developing toner particle body and the coating external additive for a long period of time. The inventors have discovered that the temperature can be controlled easily, uniformly, and with high precision, making it possible to perform desired toner surface treatment, leading to the present invention.

One aspect of the present invention is to disperse and suspend electrophotographic toner particles having a desired particle size produced by a melt mixing method in a solvent together with an external additive such as a fluidity imparting agent or a charge control agent. The surface of the toner is coated with the external additive by raising the liquid temperature of the dispersion to a temperature higher than the glass transition point of the synthetic resin constituting the toner particle body, and then coating the surface of the toner with the external additive, followed by dehydration and drying. A toner for developing electrostatic latent images and a method for producing the same.

Furthermore, after dispersing a polymerizable monomer and a colorant in a dispersion liquid and granulating polymer particles by suspension polymerization in the presence of a polymerization initiator, the temperature of the dispersion liquid of the suspension polymerization system is While maintaining the temperature higher than the glass transition point (or softening point) of the granulated resin particles, an external additive such as a fluidity imparting agent or a charge control agent is dispersed and stirred in the dispersion liquid, and the surface of the toner particles is A toner for developing an electrostatic latent image, which is coated with an external additive, dehydrated and dried, and a method for producing the toner.

(Function) The toner for developing an electrostatic latent image according to the present invention has a toner particle body mainly composed of a synthetic resin, and an external additive layer that coats the surface of the toner particle body, and The agent layer is adhered to the surface of the toner particle main body in the form of a heat-fused tube, forming an integrated structure. That is, according to the present invention, a toner particle body mainly composed of a synthetic resin, hydrophobic silica, a metal oxide such as titanium oxide, alumina, or a fluororesin such as polyfluoroethylene is used to improve fluidity or cohesion. External additives for the purpose of improving charging properties are dispersed in a dispersion liquid such as water under appropriate conditions such as using a surfactant, and the dispersion system is adjusted to the glass transition point of the resin forming the main body of the toner particles. The main idea is to heat the mixture to a higher temperature and stir it appropriately. By moderate stirring at a temperature equal to or higher than the glass transition point, fine-diameter external additive particles adhere to the softened surface of the toner particle body, forming a uniform and strong coating. Therefore, the toner for developing electrostatic latent images according to the present invention always exhibits excellent performance in terms of durability, fixability, storage stability, and image quality. In addition, since manufacturing is carried out in a dispersion/suspension form in a liquid, the toner particles for developing electrostatic latent images and the external additives to be coated can be maintained uniformly dispersed for a long time, and the temperature can be easily controlled. As a result, it is possible to perform the desired toner surface treatment uniformly and with high precision.

(Example) Hereinafter, an electrostatic latent image developing toner and a manufacturing method thereof according to the present invention will be described.

First, a general manufacturing method and components used for the toner for developing electrostatic latent images according to the present invention will be explained. For example, a monomer composition containing a polymerizable monomer such as styrene and a colorant such as carbon black may be combined with pl! 5-8
The process begins by creating resin particles by dispersing the resin in an aqueous dispersion and polymerizing it. A surfactant is used to promote the dispersion of the monomer composition, and a polymerization initiator is used to promote the polymerization reaction. Diethylamine and the like can be used to adjust the pH of the aqueous dispersion.

Examples of the polymerizable monomers include styrene, 0-methylstyrene, fog-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 its derivatives such as hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene; Saturated monoolefins; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl brobionate, and vinyl benzoate; methyl methacrylate, ethyl methacrylate, and methacrylate propyl acid, methacrylic acid n
-butyl, isobutyl methacrylate, n- methacrylate
Octyl, dodecyl methacrylate, 2-methacrylate
α-methylene aliphatic monocarboxylic acid esters such as ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate , propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, and other acrylic acid esters; vinyl methyl ether, vinyl ethyl ether, vinyl Vinyl ethers such as isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone; N-vinyl pyrrole,
N-vinylcarbazole, N-vinylindole, N-
Examples include N-vinyl compounds such as vinylpyrrolidone; vinylnaphthalenes; vinyl monomers such as acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

Examples of the polymerization initiator used in the polymerization of the above polymerizable monomers include benzoyl peroxide, di-t-butyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, potassium persulfate, ammonium persulfate, and peroxide. Acetyl, tetramethylthiuram disulfide, azobisisobutyronitrile, azobiscyclohexanenitrile, phenylazotriphenylmethane, triethylaluminum, trimethylaluminum, ethylaluminum dichloride, diethylaluminum chloride, tetraethyl lead, diethyl zinc, diethyl cadmium, tetraethyl Examples include tin, titanium tetrachloride, aluminum chloride, aluminum bromide, tin chloride, boron trifluoride diethyl etherate, boron trifluoride, zinc chloride, phosphorus pentafluoride, etc., and the amounts used are generally Approximately 0.5 in weight ratio to polymerizable monomer
~5% is sufficient.

Furthermore, as a coloring agent, for example, carbon black,
First Yellow G1 Benzidine Yellow Pigment Yellow India First, Orange, Irgazine Red, Carmine FB, Permanent Bordeaux PRR,
Pigment Orange P1 Lysole Red 2G, Lake Red C10-Damine FB, Rhodamine B Lake, Phthalocyanine Purpigment Blue, Brilliant Green B1 Phthalocyanine Green, and Quinacridone. In addition, it is also possible to use magnetic powder or CCA (charge control agent) having a coloring property as a coloring agent. The magnetic powder referred to herein is, for example, ferromagnetic metal powder such as iron, cobalt, or nickel, or powder of an alloy or compound such as magnetite, hematite, or ferrite.

Further, in the present invention, it is preferable to use a surfactant in order to promote the dispersion of the monomer composition or the external additives described below during dispersion and polymerization.

Such surfactants include, for example, sodium dodecylbenzenesulfonate, sodium tetradecylsulfate, sodium pentadecylsulfate, sodium octylsulfate, sodium allyl-alkyl-polyethersulfonate, sodium oleate, sodium laurate,
Sodium caprate, sodium caprylate, sodium caproate, potassium stearate, carunium oleate, 3,3-disulfonodiphenylurea-4,4
-Sodium diazo-bis-amino-8-naphthol-6-sulfonate, ortho-carboxybenzene-azo-
Examples include dimethylaniline, 2.2.5.5-tetramethyl-triphenylmeth, and sodium 4.4-diazobis-β-naphthol-disulfonate.

Furthermore, wax or the like may be used for the purpose of improving the releasability from the heat roller used for fixing the toner after developing the electrostatic latent image.

Such waxes include, for example, paraffin wax (manufactured by Nippon Oil), paraffin wax (manufactured by Nippon Oil), Microwa Sox (manufactured by Nippon Oil), microcrystalline wax (manufactured by Nippon Oil), and PE-130 (manufactured by Hoechst). ), Mitsui Hiwax 110P.

Mitsui Hiwax 220P, Mitsui Hiwax 660P
(all manufactured by Mitsui Petrochemicals), and particularly preferred are low molecular weight polyethylene, low molecular weight polyethylene, low molecular weight polypropylene, and paraffin. In addition, emulsion type wax is also effective.

Next, specific examples of the toner for developing electrostatic latent images and the manufacturing method thereof according to the present invention will be described. Please note that unless otherwise specified,
Quantities are indicated by weight.

Example 1 FIG. 1 is a flowchart showing the manufacturing process of a toner for developing electrostatic latent images in this example. First, polymerizable monomers consisting of 85 parts of styrene monomer, 15 parts of butyl acrylate, and 3 parts of acrylic acid are prepared. The mixture was added to an aqueous dispersion consisting of 100 parts of water, 1 part of a nonionic emulsifier (Emulgen 950), 1.5 parts of an anionic emulsifier (Neogen R), and 0.5 parts of potassium persulfate, and heated to 70°C with stirring. Polymerization A was carried out for 8 hours to obtain an emulsion.

Next, 1.5 parts of magnetite and carbon black (Regal 330R) were added to 100 parts of the emulsion obtained above.
Water B containing 0.1 part of sodium dodecylbenzenesulfonate as a surfactant was added to the mixture, and diethylamine was added to adjust po to 5.5 to obtain a reaction dispersion for suspension polymerization. Thereafter, the reaction dispersion for suspension polymerization was preliminarily stirred and then dispersed with a nanomizer, and the reaction dispersion was further heated to 60° C. with stirring, hydrogen peroxide was added, and polymerization C was performed for 6 hours.

It is also known that in the polymerization step C, oil droplets of the polymerizable monomer are added little by little to proceed with polymerization and granulation in parallel. The particle size of the resin particles was about 0.5 to 1 μm. By further gradually raising the temperature of this reaction dispersion system C to 80 to 90°C and holding it for about 30 minutes to 4 hours, the particle size of the resin fine particles to be granulated can be changed in the range of 2 to 20 μm. (granulation process). In this example, 3 hours (90°C)
By maintaining the temperature, resin particles (toner particle bodies) of about 11 μm were produced.

A part of the granulated particles (toner particle body) obtained above was taken out, washed with water, and dried under reduced pressure at 45°C for 10 hours. When the point was measured, it was 62°C.

On the other hand, after washing the granulated toner particle body with water to remove floating components, it was dispersed in 600 parts of water, and then hydrophobic silica fine powder (R972) with a particle size of 15 to 20 μm (millimicrons) was added. 6 parts were previously dispersed and wetted in 50 parts of methanol using a high speed stirrer (nanomizer) and then added to the particle dispersion. In addition, the hydrophobic silica fine powder may be dispersed as it is without washing with water at the stage where polymerization granulation is completed.
Although it has the advantage of simplifying the process, if there is a large amount of reaction residue, it is preferable to perform a simple rinsing. When the particles have been completely washed, it is preferable to add again 0.05 to 0.1 part of the surfactant used in the polymerization step to disperse the resin particles and external additives.

Next, the above dispersion was heated to 80°C while being heated for 2-b, and then stirred for 30-70 minutes using a propeller type stirrer (homogenizer) to the extent that relatively strong turbulence was caused. An external additive layer was formed on the surface of the resin particles. After that, remove the water using filter paper and perform washing F with distilled water.
Drying under reduced pressure was carried out at 45° C. for 10 hours to obtain dry toner particles that had been surface-treated (external additives were applied), and the toner particles were passed through a classifier to remove coarse particles. This classification step H is unnecessary unless coarse particles are generated, and is not an essential step in the present invention.

Next, the particle size distribution of the toner particles obtained above was determined using a Coulter counter at 11 FI, and it was found to be 50%.
The average particle size was 12.5 μm. This toner particle 1
Ferrite carrier for electrophotography (FSL1) per kg
A two-component developer was prepared by mixing 40 g of 020B).

In addition, the amount of charge of this two-component developer (toner) was measured using a commercially available blow-off charging machine.
Minus 34μc/g (microcoulomb/gram)
Met. Further, for a toner storage test, no aggregation or solidification was observed even after the toner was placed in a polyethylene container and left in a water tank at 50° C. for 20 hours. Furthermore, although a quantitative evaluation of the fluidity of the toner was omitted, it was easily found that the toner had higher fluidity in a sensory comparison test with existing toners by shaking a transparent container.

Using this toner, a commercially available electrophotographic copying machine (BD511)
When a copy image was taken using the developer (manufactured by Toshiba), initial characteristics such as image density, white background stain, sharpness, and fixing properties were equal to or better than those of the regular developer used in the test copying machine. Furthermore, in order to test the durability of this developer, a large amount of toner was made under the same conditions as above and 50,000 copies were made, but almost no filming of toner components on the photoreceptor was observed. In addition, there was much less change in image quality compared to the regular developer, and it was confirmed that printing durability was improved.

Further, when this toner was observed under an electron microscope, it was found that it had an almost perfect spherical shape due to thermal melting, and its surface was extremely uniformly and densely coated with hydrophobic silica. Moreover, almost no change in this appearance was observed even after the life test. This is because during the manufacturing process, the resin particles are placed at a temperature higher than the softening temperature or glass transition point and come into contact with the silica particles in a viscous state, so a strong force is applied to completely adhere or fuse them. This is thought to be due to the fact that it is covered with

Moreover, the coated external additive is not completely buried inside the toner particle main body, but is attached to the surface in an exposed state (
This is the most important feature of the toner of the present invention, and is the reason why it exhibits high fluidity, storage stability (blocking resistance), and high durability that could not be achieved with conventional addition methods. It is judged that. Furthermore, the reason why almost no silica is observed to be attached to the carrier is that even if there is silica that is attached or floating, it is removed by cleaning after the coating treatment. In the end, it is determined that the fact that it does not exist also contributes.

Comparative Example 1.2 Under the same conditions as in Example 1, the polymerized and granulated resin particles (toner particle bodies) were washed, dried, and classified under the same conditions as in Example 1. 1 part of hydrophobic silica (R972) (Comparative Example 1) or 1 part of hydrophobic silica (R972)
0 parts (Comparative Example 2) was added and mixed for 30 minutes in a ball mill (
(dry mixing) to produce two types of toners.

When these were observed using an electron microscope, it was found that in the case of Comparative Example 1, the silica powder was localized and did not cover the entire particle surface, and the adhesion force was weak. was found to be missing. In addition, the image quality suddenly decreased in density after about 20,000 copies.

On the other hand, in the case of Comparative Example 2, although it appears that silica partially covers the entire surface of the toner, many pieces of silica that are not attached and are in a floating state are observed. This toner had an extremely low image density from the beginning and caused poor cleaning, making it unusable.

This is considered to be because a large amount of silica is released from the toner.

Further, in a storage test under the same conditions as in Example 1, in Comparative Example 1, there were parts of the toner that were not crushed unless strongly vibrated, and the storage stability was insufficient.

Examples 2 to 4, Comparative Examples 3 to 5 Using the same composition as in Example 1 above, silica powder was added to the dispersion system, and the conditions for covering/covering the surface of the resin particle body were changed after increasing the temperature. Only the temperature of 50℃, eo”c, 7
Toner for developing electrostatic latent images was prepared under the same manufacturing conditions except that the temperature was 0° C., 90° C., 100° C., or 110”C.

Comparative Example 3 The temperature when adhering/coating to the surface of the resin particle body was set to 5.
When processed at 0°C, there were no abnormalities in the image or toner appearance initially, but after just a few copies, white deposits that were not cleaned appeared on the photoreceptor. There are problems with the image. Further, the amount of charge was reduced to about 10μcog. It is understood that these problems occurred because the silica particles added in large amounts were not sufficiently fused to the polymer particles.

Comparative Example 4 The temperature when adhering/coating to the surface of the resin particle body was set to 8
The sample treated at 0°C had almost no difference from Comparative Example 1.

Example 2 The temperature when adhering and coating the resin particle main body surface was set to 7.
In the case of the photoreceptor processed at 0° C., white deposits began to form on the photoreceptor after several hundred copies were made, but the degree of damage to the image was slight.

Example 3 In the case of Example 2, a toner was prototyped under the same conditions except that the temperature raising and holding time was extended to 4 hours, and the same copying test was conducted, and it was found that it had almost the same characteristics as in Example 1. Toner was obtained.

Example 4 The temperature when adhering and coating the resin particle main body surface was set to 9.
When the toner was processed at a temperature of 0° C., almost the same good results as the toner obtained in Example 1 were obtained.

Comparative Example 5 The temperature when adhering/coating to the surface of the resin particle body was set to 1
When processed at a temperature of 10℃, the amount of charge was 15μc/
In g, although no abnormality was observed in the image, the fluidity was decreased, and agglomeration and solidification were observed in some parts as a result of the storage test. Observation using an electron microscope revealed that the surface had changed to a smoother state than that of Example 1. This is thought to be because the polymer particles melt excessively due to the high temperature and eat into the silica particles. There is also a change (increasingly high) in the fixing temperature of the toner, suggesting that coating treatment at too high a temperature is not appropriate.

Example 5 In the case of Example 1, an external additive with a particle size of 0.5
~2μm fluororesin fine powder (trade name Kynar) 6 parts,
A toner was prepared under the same conditions except that the amount of surfactant was 0.2 parts. The charge amount of this toner is -40
When a copying test was conducted using μC using the same copying machine as in Example 1, good images were obtained. In addition, both storage stability and fluidity were good.

Example 6 A toner was prepared under the same conditions as in Example 1 except that the amount of external additives was 10 parts and methanol was 90 parts. Almost the same results as in Example 1 were obtained with this toner. This is presumably because even if the external additive is excessively dispersed, the excess external additive is not taken in, so there is a degree of leeway in the appropriate amount of external additive dispersion.

Example 7 In the case of Example 1, the resin particle body was changed to 12 parts of silica and 100 parts of methanol in the state where granulation after polymerization was not performed, that is, the particle size was 0.5 to 1 μm.
A toner was obtained by processing under the same conditions as in Example 1.

50 parts of this toner was added to 2000 parts of kerosene (manufactured by Isoper H1 Schal Sekiyu), and 4 parts of methanol was added as a dispersion stabilizer.
It was dispersed together with 0 parts to prepare a developer.

When commercially available electrophotographic organic photosensitive paper was charged to +500 volts in a dark place using this developer, imagewise exposed, and then developed, a good image was obtained with no problems in density or background smudge. It was done. When this image was corona-transferred onto commercially available PPC paper, an extremely sharp and precise image without bleeding was obtained, and this image could be melted and fixed onto the container using an infrared heater. Even after this developer was left in a water bath at 50° C. for 12 hours, it did not aggregate or solidify.

Example 8 Using styrene-acrylic acid ester co-assembly resin (Mitsubishi Rayon, glass transition point 65°C) as a binder resin, 100 parts of toner with an average volume particle size of 10 μm and no additives was prepared by a kneading and pulverizing method. Sodium dodecylbenzenesulfonate 0.1 as a dispersion stabilizer in 5000 parts of water
After mixing 5 parts of hydrophobic silica (R972) with 70 parts of methanol, the mixture was added to the toner dispersion, and the temperature was gradually raised to 90° C. and maintained for 4 hours with stirring. The following steps are the same as in Example 1, including cleaning,
It was dried and classified to obtain a toner.

When the charge amount of this toner was determined using the same carrier as in Example 1, it was found to be 38 μC. Also,
The appearance was almost completely spherical, and the state of the silica coating was also very similar to that of Example 1. Good results were also obtained regarding image characteristics and storage stability.

Comparative Example 6 In the case of Example 8, hydrophobic silica (R9
72) without the addition process, 1% hydrophobic silica was added to the toner weight by the conventional dry mixing method (addition method).
Created toner. When this toner was observed under an electron microscope, it was found that the silica powder was localized and did not cover the entire surface of the particles, and the shape of this toner produced by a pulverization method was irregular.

Further, in a storage test under the same conditions as in Example 1, there were parts of the toner that were not crushed unless strongly vibrated. Furthermore, although detailed prototype conditions are omitted,
Other toners with a glass transition point of 70° C., which were produced using the kneading and pulverizing method and which were able to withstand this storage test, did not have sufficient fixing strength even when the fixing temperature was raised to 200° C.

It should be noted that the developing method used for the toner of the present invention is not limited to the methods exemplified above, and it will be understood that the toner exhibits its functions in common in all conventionally known developing methods. .

From the study of the above examples and comparative examples, it has been found that resin particles (toner body) having desired particle size and thermal properties are formed by suspension polymerization, and the temperature during coating of external additives added after resin particle formation is By selecting a temperature higher than the glass transition point of the resin particles, that is, higher than the softening temperature of the synthetic resin, and lower than the viscosity temperature or thermal fluidity temperature of the synthetic resin that makes up the toner particle body, high-performance toner particles can be obtained. can get. Further, toner particles obtained by the melt-kneading method can also be coated with an external additive in a solvent such as water to obtain desired high-performance toner particles.

In addition, when using a component that melts at a relatively low temperature, such as wax, it is not preferable to use a component that melts at a relatively low temperature because elution tends to occur at too high a temperature. On the other hand, a series of studies revealed that there is a relatively large margin for temperature and time for increasing 7iA, and even if the attached external additive is buried inside the resin particles, the surface of the resin particles will regain viscosity. In order to restore the surface, a new external additive is attached, and the external additive that is not completely buried is always attached to the surface in a semi-exposed state.

[Effects of the Invention] As described above, according to the toner for developing electrostatic latent images and the manufacturing method thereof according to the present invention, particle formation after kneading and pulverization or after completion of polymerization, that is, thermal conditions for toner particle bodies Since the surface coating treatment is carried out after the establishment of the external additives, the external additives are coated with high strength under relatively flexible conditions, resulting in long life and good fluidity and storage stability (flocculation resistance). It is possible to provide a highly functional dry or wet developing toner that exhibits the following properties.

Further, even if a resin having a low constant temperature of 4 m degrees is used, in the case of the present invention, the storage stability is improved, the fixing performance is improved, and the fixing temperature can be kept low.

In other words, there is an advantage that the temperature rise and power consumption of the developing device can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an example of the manufacturing process of a toner for developing an electrostatic latent image according to the present invention. A... Monomer prepolymerization step B... Dispersion with blue agent C... Polymerized fine particle generation step D... Granulation step E... ...External additive coating process F...Filtration/washing process G...Drying process H...Classification process Applicant: Toshiba Corporation

Claims (3)

[Claims] (1) Comprising a toner particle body for electrostatic latent image development which is mainly composed of a synthetic resin and has a predetermined particle size, and an external additive that adheres to and coats the surface of the toner particle body for electrostatic latent image development. , in a mixed dispersion in which the external additive includes a toner particle body for electrostatic latent image development and an external additive having a particle size smaller than that of the toner particle body, the temperature of the dispersion liquid is adjusted to the temperature of the toner particle body. A toner for developing electrostatic latent images characterized by being formed by stirring and coating while maintaining the temperature higher than the glass transition temperature of a resin. (2) A step of generating and creating a toner particle body for developing an electrostatic latent image which is mainly composed of a synthetic resin and having a predetermined particle size, and dispersing the toner particle body for developing an electrostatic latent image in a dispersion liquid. , a step of further adding and dispersing an external additive having a particle size smaller than that of the toner particle main body for electrostatic latent image development; The electrostatic latent image developing toner particles are stirred while being maintained at a temperature higher than the glass transition point of the electrostatic latent image developing toner, and the surface of the toner particles for developing an electrostatic latent image is coated with the external additive, followed by washing, dehydration, and drying. A method for producing a toner for electrolatent image development. (3) a step of dispersing at least a polymerizable monomer in a dispersion liquid and performing suspension polymerization in the presence of a polymerization initiator to produce toner particle bodies for electrostatic latent image development having a predetermined particle size; , further adding and dispersing an external additive having a particle size smaller than the toner particle main body for electrostatic latent image development into the dispersion medium of the toner particle main body for electrostatic latent image development; and controlling the solvent temperature of the dispersion system. The toner particles for electrostatic latent image development are stirred while being kept at a temperature higher than the glass transition temperature of the synthetic resin that makes up the body of the toner particles, and the surface of the toner particles for electrostatic latent image development is coated with an external additive, and then washed and dehydrated. A method for producing a toner for developing an electrostatic latent image, the method comprising the following steps: