JPH0237363A - Toner composition - Google Patents

Abstract

PURPOSE:To maintain good clean ability even under high temperature and high humidity by using as a fatty acid metal salt a mixture of aluminum stearate and zinc stearate adjusted to a specified mixing ratio. CONSTITUTION:The mixture of aluminum stearate and zinc stearate adjusted to a mixing ratio of 1:1-4:1 is added to the outside of the toner in an amount of 0.05-0.1wt.% of the toner powder, and it is preferred to set the ratio of zinc stearate to the toner in an amount of 0.005-0.025wt.% of the toner. If the zinc stearate is added over its upper limit, the resistivity of the toner and a developer are deteriorated, an blotting of an image and deterioration of resolution become liable to occur, and if it is below the lower limit, the cleanability enhancing effect becomes poor, and it becomes remarkably low as copying operations are continued under an adverse environment of high temperature and high humidity, and cleanability not deteriorated under such a sever environment by controlling the mixing ratio in the prescribed range.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a toner composition for developing electrostatic images, and more specifically, the present invention relates to a toner composition for developing electrostatic images, and more specifically, it has excellent cleaning properties, does not deteriorate in performance even under high temperature and high humidity, and has high The present invention relates to a toner composition that provides high-resolution images.

(Prior art and its problems) Conventionally, in a copying machine using an electrophotographic method, an electrostatic latent image formed on a photoreceptor having a photosensitive layer containing an inorganic or organic photoconductive substance is processed by a dry developing method. For visualization, various powder toners are used in which additives such as colorants are dispersed in a binder resin.

In the electrophotographic method, an electrostatic latent image formed on the photoreceptor by charging and exposure to light is developed with the toner, and the toner image formed on the electrostatic latent image is transferred to a support such as transfer paper. At the same time, the toner image is fixed on the support by a fixing means such as a heating roller or a pressure roller, thereby making the electrostatic latent image visible. Further, after the toner image is transferred to the support, the remaining toner on the photoreceptor is scraped off by a cleaning blade in order to clean the toner remaining on the photoreceptor. If this cleaning step is repeated, the photoreceptor is damaged, and the toner is fused to the photoreceptor due to frictional heat between the photoreceptor surface and the cleaning blade, and toner adhesion gradually grows. especially,
If the photoconductor is not smooth or if there are protrusions or holes on the photoconductor, damage to the photoconductor will increase, and toner will tend to stick to the surface of the photoconductor in a linear form. Toner smear occurs on the reproduced image, reducing the quality of the reproduced image.

Therefore, in order to solve the above-mentioned problems, it has been conventionally proposed to add a fatty acid metal salt as a lubricant to the above-mentioned electrostatic image developing toner.

In addition, in recent years, copying machines have been developed not only for office use in offices, but also for personal use at home.
By using a process unit that integrates a photoconductor, developing device, cleaning device, etc., users can replace the process unit themselves as the photoconductor reaches its end of life, and the used process unit can be disposed of as a whole, making it maintenance-free. The goal is to As the photoreceptor, a photoreceptor having an organic photoreceptor layer is often used from the viewpoint of safety and manufacturing cost.

However, the organic photosensitive layer has a high affinity with the fatty acid metal salt, and the fatty acid metal salt easily forms a film on the surface of the photoreceptor, and the filmed fatty acid metal functions as an insulating layer. Coupled with the fact that the surface potential of a photoreceptor having such a photoreceptor is generally low, there is a problem in that the photosensitive characteristics of the photoreceptor and, as a result, the quality of the copied image deteriorates.

In particular, the addition of fatty acid metal salts significantly lowers the resistance of the developer, causing toner smearing in the vicinity of solid areas of images.

Therefore, the present inventors previously reported in Japanese Patent Application No. 61-24259 that among fatty acid metal salts, aluminum stearate in particular can impart good cleaning properties within the range of not significantly reducing the resistance of toners and developers. proposed.

However, upon further investigation, the inventors found that
Aluminum stearate generally has a low cleaning effect per unit weight, and is used when the developer is housed in a narrow space like the process unit mentioned above where it is sealed and easily affected by pressure and temperature changes, or when exposed to high temperatures. - When copying operations are continued in a high humidity environment, if the fluidity of the developer decreases and poor dispersion of aluminum stearate occurs, the amount of developer per unit area in contact with the photoreceptor will decrease. There is a large difference in cleaning performance depending on the amount of aluminum stearate present, and stable cleaning performance cannot be imparted uniformly or continuously in the width direction of the photoreceptor.
As the printing cycle progresses, cleaning defects become more likely to occur. In addition, 1. The occurrence of aggregates due to poor dispersion of aluminum stearate and fluctuations in electrical resistance due to moisture absorption of the developer combine to cause image blurring and a decrease in resolution.

Therefore, in view of the above points, the present inventors have conducted extensive studies and have arrived at the present invention.

That is, an object of the present invention is to provide a toner composition that maintains good cleaning properties even at high temperatures.

Furthermore, another object of the present invention is to provide a toner composition that is durable, can reduce the effects of poor dispersion, and can provide high-resolution copies.

(Means for Solving the Problems) According to the present invention, a mixture of aluminum stearate and zinc stearate adjusted to a mixing ratio of 1:1 to 4:1 is mixed with 0.00 parts by weight per 100 parts by weight of powder toner. 05 to 0.1
By externally adding parts by weight, the above-mentioned problems can be solved and the object of the present invention can be achieved.

(Function) An important feature of the present invention is that aluminum stearate/zinc stearate is used as the fatty acid metal salt after being adjusted to a specific mixing ratio.

As mentioned above, aluminum stearate is superior to other fatty acid metal salts in that it does not significantly reduce the electrical resistance of the developer. Table 1 is a table showing changes in the amounts of various metal stearate salts added to toner and the resistance value of the developer. As described above, aluminum stearate has a poor effect of imparting cleaning properties per unit weight, so in order to impart cleaning properties, aluminum stearate must be added in a relatively large amount to the toner compared to other metal salts of fatty acids. Bye. On the other hand, zinc stearate can improve the cleaning performance when present in a small amount relative to the toner, but the electrical resistance of the toner and developer decreases drastically depending on the amount added, and the developer properties change due to fluctuations in the dispersion state. This condition is likely to worsen and cause image blurring.

Therefore, the present inventors have found that by mixing aluminum stearate and zinc stearate in a suitable range, the characteristics of each can be effectively utilized, there is less variation in image quality due to poor dispersion, and the electrical resistance of the developer is suitable. Within this range, a small amount of zinc stearate further supplements the cleaning improvement properties of aluminum stearate, which reduces the decrease in cleaning properties due to poor dispersion and prevents image blurring even in high temperature environments. First, they discovered that high-resolution images can be obtained.

The present invention will be explained in more detail below.

The toner used in the present invention includes, as a binder resin, a styrene polymer, an acrylic polymer, a styrene-acrylic polymer, a polyethylene, a chlorinated polyethylene, a polypropylene, an olefin polymer such as an ionomer, polyvinyl chloride, polyester, polyamide, polyurethane,
Examples include various polymers such as epoxy resin, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin, phenol resin, rosin-modified phenol resin, xylene resin, rosin-modified maleic acid resin, and rosin ester. Among these, styrene polymers, acrylic polymers, or styrene-acrylic polymers, particularly styrene-acrylic polymers, are preferred because they are easy to control in terms of crushability and molecular weight distribution. These polymers have a weight average molecular weight of 30.000 to 200.0.
00, particularly preferably in the range of 50,000 to iso, ooo, and one type or a mixture of two or more types may be used.

Among the above polymers, rosin esters, rosin-modified phenolic resins, rosin maleic acid resins, epoxy resins, polyesters, cellulose polymers, and polyether resins are useful in improving the triboelectric properties of toner. It is.

The above-mentioned polymers preferably have a softening point of generally 50 to 200°C, particularly 70°C to 170°C.

Also, when the toner is a pressure fixing toner.

Polymers whose compositions can easily be changed are used, such as olefin polymers such as polyethylene and polypropylene, and polyamides. This polymer may contain other polymers, such as polyvinyl acetate, ethylene-vinyl acetate copolymer, hydrogenated polyethylene, hydrogen rosin ester, aliphatic, alicyclic or aromatic petroleum resin, etc. May be contained.

Examples of the coloring agent dispersed in the binder resin include carbon black, lamp black, chrome yellow, Hansa yellow, benzidine yellow, Bethlen yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, Palkan orange, Watch Young Red,
Permanent Red, Brilliant Carmiso 3B, Brilliant Carmine 6B, Danibon Oil Red Pyrazolone Red, Lysole Red, Rhodamine B Lake, Lake Red C10-Z Bengal, Aniline Pul, Ultramarine Blue, Calco Oil Blue Methylene Blue Chloride, Phthalocyanine Pul, Phthalocyanine Green, Malachite green off-salate etc. or C, 1,
5olvent Yellsm 60%C, 1,5ol
vent Red 27, C, 1,5olvent B
Examples include oil-soluble dyes such as lue 35 and the like.

These colorants may be used singly or in a mixture of two or more, and in an amount that provides a sufficient toner image density, for example, 1 part resin.
1 to 30 parts by weight, preferably 2 to 20 parts by weight per 00 parts by weight.

Further, when the toner is a magnetic toner, a magnetic substance can be contained together with or in place of the colorant. The above-mentioned magnetic material may be any material that exhibits magnetism or is magnetizable; for example, ferrite, magnetite, iron, cobalt, nickel, manganese, or other ferromagnetic metals or alloys, or these metals. Examples include compounds containing the following. These magnetic substances have an average particle size of 0.1 to 1 μm, and are used singly or in combination of two or more, and are generally used in amounts of 5 to 10 parts by weight of resin.
70 parts by weight, preferably 20 to 50 parts by weight are used.

In order to control the charge of the toner, the toner may contain a charge control agent, such as an oil-soluble dye such as nigrosine dye, oil black, or soubiron black, or manganese such as naphthenic acid, salicylic acid, octylic acid, fatty acid, or resin acid. iron,
Metal soaps such as metal salts of cobalt, nickel, lead, zinc, cerium, calcium, etc., metal-containing azo dyes, pyrimidine compounds, alkyl salicylic acid metal chelates, etc. are added in an amount of 0.1 to 5 weight parts per 100 parts by weight of the binder resin. It is preferable to use one part.

The above-mentioned toner also contains anti-offset agents, such as various waxes such as low molecular weight polypropylene, low molecular weight polyethylene, and paraffin wax, and olefin monomers having 4 or more carbon atoms, in order to prevent the toner from adhering to the fixing roller. 0 of low molecular weight olefin polymers, fatty acid amides, silicone oils, etc. per 100 parts by weight of binder resin.
．． Preferably, the content is 5 to 15 parts by weight.

Then, while protecting the photoreceptor with the powder toner,
To prevent the adhesion of sushi-like toner on the surface of the photoconductor and to prevent deterioration of developer properties (in order to obtain high-quality images,
1:1 aluminum stearate and zinc stearate
The mixture adjusted to a mixing ratio of 4:1 to 10:1 is used as a powder toner.
0.05 to 0.1 part by weight is added externally.

The above mixing ratio can be appropriately determined depending on the total amount of metal stearate added, but the toner 100! It is preferable to adjust the mixing ratio so that the amount of zinc stearate is 0.005 to 0.025 parts by weight per part of zinc stearate.

If the ratio of zinc stearate increases beyond the above mixing ratio, it will lower the resistance value of the toner and developer.
Image blurring and a decrease in resolution tend to occur.

Furthermore, if the mixing ratio is less than the above, the effect of imparting cleaning properties will be poor, and the cleaning properties will deteriorate significantly as the printing life progresses at high temperatures and under high temperatures.

Furthermore, if the mixture is added to the toner in an amount larger than the above range, the resistance of the developer will decrease too much and the filming of the metal stearate on the surface of the photoreceptor will tend to occur, resulting in a decrease in image quality. Put it away.

In addition, an abrasive substance may be added to the above-mentioned toner. When a film of the fatty acid metal salt is formed, this film is polished to clean the photoreceptor, and the characteristics of the toner and the photoreceptor are Any material can be used as long as it does not have a negative effect on the body or image, for example,
Aluminum silicate, surface-treated aluminum silicate, etc. may be talc, kaolin, barium sulfate, etc.
Titanium dioxide, calcium carbonate, antimony trioxide, barium titanate, calcium titanate, strontium titanate, magnesium oxide, calcium silicate, zinc oxide, and zirconium oxide are preferred, especially colloidal silica and surface-treated hydrophobic Polysilica is preferred. By the addition of the above-mentioned abrasive substances, especially hydrophobic silica, toner,
The fluidity of the developer also improves, and the charging properties and image characteristics of the toner are improved. In addition, the above-mentioned polishing substance has an average particle size of 5 to 1
00 mμ, particularly preferably 10 to 30 mμ. If the particle size of the abrasive substance deviates from the above range, the above effects will be reduced, which is not preferable. Preferred specific examples of the above-mentioned polishing materials include Aerosil R972J (average particle size 16 mμ) manufactured by Nippon Aerosil Co., Ltd.

The abrasive substance is preferably added in an amount of 0.005 to 0.3 parts by weight per 100 parts by weight of the powder toner. If the amount of the abrasive substance added is less than 0.05 part by weight, the fluidity of the toner will be poor, and if it exceeds 0.3 part by weight, the photoreceptor will tend to be easily damaged.

In addition, an electrical resistance adjusting agent may be added to the above powder toner in order to adjust the electrical resistance of the toner and developer, as well as image characteristics such as gradation and density, and obtain high quality images. good.

As the electrical resistance adjusting agent, any material can be used as long as it can adjust the electrical resistance of the toner and does not adversely affect the characteristics of the toner, the photoreceptor, and the image, such as carbon black. However, aluminum oxide is preferred because it allows fine adjustment of electrical resistance.

The electrical resistance adjusting agent preferably has a particle size similar to that of the above-mentioned material, and for example, "
Aluminum oxide CJ (average particle size 20mμ)
etc. can be exemplified.

The electrical resistance adjuster is preferably added in an amount of 0.05 to 0.3 parts by weight per 100 parts by weight of the powder toner. If the amount of the electrical resistance adjuster added is less than 0.05 parts, it will be difficult to finely adjust the electrical resistance. Moreover, if the amount exceeds 0.3 parts by weight, blurring of images is likely to occur.

In order to improve the fluidity of the toner, the surface of the toner may be treated with a compound having a low surface tension such as a silane coupling agent, silicone oil, or a fluorine compound. Furthermore, if desired, the powder toner may be heat-treated to smooth the corners and the like in order to improve the fluidity of the toner.

The above powder toner preferably has a particle size of 1 to 30 IJm, preferably 5 to 25 μm.

The toner of the present invention is useful as either a one-component developer or a two-component developer. - When used as a component developer, the toner containing the above-mentioned magnetic substance is used alone as a developer, and when used as a two-component developer, an uncoated carrier such as glass beads, oxidized or unoxidized iron powder, ferrite, etc. Alternatively, a coated carrier is used in which a magnetic material such as iron, nickel, cobalt, or ferrite is coated with a polymer such as an acrylic polymer, a fluorographic polymer, or a polyester.
It has a particle size of 2000 μm to 2000 μm. Further, when a developer consisting of the above-mentioned toner and carrier is used, the toner concentration used is 2 to 15% by weight.

Further, as the electrostatic latent image carrier, selenium, selenium-
Used for photoreceptors with inorganic photoconductive layers such as tellurium, zinc oxide, cadmium sulfide, and amorphous silicon, photoreceptors with organic photoconductive layers containing charge-generating substances and charge-transporting substances, electrostatic recording paper, etc. However, it is particularly useful for photoreceptors having organic photoconductive layers. The toner for developing an electrostatic latent image can be developed using a conventional developing method, for example, when it is a component developer, a bristle brush method, a magnetic brush method,
It is developed by a powder cloud development method, or, if it is a two-component developer, by a cascade development method, a magnetic brush development method, or the like.

The present invention will be explained in more detail below using experimental examples and examples.

(Experiment example) 90% by weight of styrene-styrene-acrylic copolymer as a binder resin, 7.5% by weight of carbon black as a colorant, 1.5% by weight of low molecular weight polypropylene as an offset inhibitor, and as a charge control agent. nigrosine dye 1
．． After melting and dispersing 0% by weight using a heated roll mill, the particles are coarsely pulverized and classified to obtain an average particle size of 5 to 20μ.
m powder toner was prepared.

To 100 parts by weight of the above-obtained toner, aluminum stearate, lithium stearate, and barium stearate were added and mixed in the proportions shown in Table 1 to prepare a toner composition.

Further, 4.5 parts by weight of the above toner composition and an average particle size of 5 parts by weight were used.
A developer was prepared by uniformly mixing 95.5% by weight of ferrite carrier having a diameter of 0 to 80 μm in a ball mill.

When the electrical resistance of the above developer was measured, the following table-
The results shown in 1 were obtained.

The electrical resistance values in Table 1 indicate the high electrical insulation properties of the toner composition (because it was difficult to accurately measure the electrical resistance value of the toner itself, the electrical resistance value of the developer described above is shown). In other words, the electrical resistance value is the same as that of the developer 2.
00 mg was placed between electrodes with a distance of 2 mm between the electrodes, and the magnet was slowly brought closer to both poles. After moving the magnet several times to make the developer uniform, the temperature was 23°C, the relative humidity was 6.
This is the average value of the values measured five times at 0''C±5% and an applied voltage of 500cm.

(Hereinafter, blank spaces) (Example) The mixing ratio of aluminum stearate and metal stearate was adjusted within the mixing ratio of 1:1 to 4:1 for 100 parts by weight of toner prepared in the same manner as the above experimental example. Furthermore, 2 parts by weight of hydrophobic silica (Aerosil R972J, manufactured by Nippon Aerosil Co., Ltd.) and aluminum oxide (
0.2 parts by weight of "Aluminum Oxide C" (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed uniformly to prepare a toner composition.

The above toner composition contains 4.5% by weight and an average particle size of 50%.
~80μmk Ferrite carrier 05.5% by weight
A developer was prepared by uniformly mixing the two in a ball mill. Then, it was 35°
After printing 10,000 sheets under a high temperature and high humidity environment of 185% C, printing was further continued, and the cleaning properties, development characteristics, and image characteristics were examined.

The results are shown in Table 2 below.

(Comparative example) A developer prepared in the same manner as in the above example was used, except that zinc stearate was not added and only aluminum stearate was added to the toner, and a photoreceptor having an organic photosensitive layer was used. Copy machine (manufactured by Sanda Kogyo Co., Ltd., DC-
After printing 10,000 sheets in the same manner under a high temperature environment of 35° C. 185% using a modified machine (Modified machine 111C), cleaning properties, development characteristics, and image characteristics were examined.

The results are shown in Table 3 below.

(Hereinafter, blank space) As is clear from the above Examples and Comparative Examples, the developer of the present invention works particularly well under high temperature and high humidity conditions, improves cleaning properties, and improves long-term cleaning properties. It can be seen that good developability can be maintained.

(Effects of the Invention) According to the present invention, even in a bad environment of high temperature and humidity,
It is possible to provide a toner composition that does not deteriorate the nigration properties and development characteristics and can continue for a long period of time and provide high image quality. In particular, the above effects are effectively exhibited in an image forming apparatus equipped with a photoreceptor having an organic photosensitive layer.

Claims (1)

[Claims] 1: aluminum stearate and zinc stearate
The mixture adjusted to a mixing ratio of 1 to 4:1 is used as powder toner 1.
1. A toner composition characterized in that 0.05 to 0.1 part by weight is externally added to 0.00 parts by weight.