JPS5929861B2 - Toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic image developing toner for developing electrostatic images formed in electrophotography, electrostatic recording, electrostatic printing, or the like.

An electrostatic charge image can be developed into a visible image by adhering developing particles due to its electrostatic attraction, but as a developer for this electrostatic charge image, in addition to liquid developer, there are powder developing agents. agents are currently widely used. Powder developers can be roughly divided into two-component developers, which are composed of a mixture of two types of powder called toner and carrier, and one-component developers, which are composed only of toner powder. A two-component developer achieves development by adhering a charged toner to an electrostatically charged image through friction with a carrier.The toner consists of a natural or synthetic resin containing a colorant such as carbon black and A powder with a particle size of 1 to 50 tt containing dispersed charge polarity control agents such as dyes, quaternary ammonium compounds, and specific resins is used, and as a carrier, iron powder, glass beads, and core particles containing these particles are used. Particle size 50-5 consisting of coated particles with a resin coating layer on the surface.
00μ powder is used. In addition, the toner constituting the one-component developer has the same composition and particle size as the toner of the two-component developer described above, and instead of the carrier, a brush-shaped or plate-shaped toner having the same function as the toner of the two-component developer can be used. It is known that toner is charged by friction with a friction member such as, for example, and recently, a toner containing a dispersed magnetic fine powder that also acts as a coloring agent in a resin is used to prevent mutual friction. Toners that are electrostatically charged have been developed. Therefore, the toner and carrier of the two-component developer and the toner of the one-component developer as described above are easily charged by frictional operations such as stirring.
Moreover, it is naturally necessary that the material be charged to an appropriate amount to suitably develop an electrostatic image.

In this regard, since the toner has resin as its main component in any developer, the triboelectric charging characteristics of the toner can be changed by incorporating various additives into the resin. In fact, toners for developing electrostatic images having various triboelectric charging characteristics by specifying the type and content of the additive substance have been proposed. Generally, toner for developing electrostatic images in electrophotography needs to be charged to a charge amount of 10-5 to 10-6 coulombs/gram, but in order to stably achieve good development, It is necessary that the toner has the characteristic of always being charged with a constant amount of charge.

However, conventional toners for developing electrostatic images have a common drawback that although they are easily charged to an amount of charge greater than that required for development, the amount of charge changes greatly due to slight changes in various conditions. For example, in a two-component developer, as development is repeated, only the toner is consumed and the toner concentration in the developer decreases, but such a change in toner concentration causes a large change in the amount of charge on the toner. Furthermore, regardless of whether the toner is a one-component developer or a two-component developer, a slight change in the toner composition or manufacturing process greatly changes the amount of charge on the toner, making it impossible to obtain a stable charging state. Due to the above-mentioned circumstances, conventional toners for developing electrostatic images are made to have the characteristic of being charged with an excessive amount of charge in order to secure the amount of charge necessary for development, and as a result,
The following drawbacks arise.

That is, in the case of a two-component developer, the mutual attraction between the toner and the carrier becomes excessive due to excessive charging of the toner, resulting in insufficient density of the developed image. In electrophotography, the surface of the photoreceptor is damaged by the adhered carrier, or the surface of the fixing roller is damaged, making it impossible to form a good copy image. Further, due to the above-mentioned change in toner concentration in the developer, good development cannot be performed many times, and the life of the developer is short. In addition, in the case of a one-component developer, excessive charging of the toner increases the cohesiveness of the toner, making it difficult to manufacture and handle the toner. Due to toner adhering to the toner, the developed image becomes of poor quality with a lot of fogging (or background smearing).

The present invention eliminates the above-mentioned drawbacks, and can be charged to a state with an appropriate amount of charge, and the charging state is uniform and stable, so that a visible image having a constant image density is always formed. An object of the present invention is to provide a toner for developing an electrostatic image.

Another object of the present invention is to provide a toner for developing electrostatic images that is not overly charged and is therefore free from various problems caused by excessive charging and is capable of forming excellent visible images. be. Still another object of the present invention is to provide a toner for developing electrostatic images that has a wide tolerance to variations in conditions in the triboelectric charging process, composition, manufacturing process, etc.

Another object of the present invention is to provide a two-component developer toner that has excellent triboelectric charging properties, can achieve excellent development, and prevents carrier from adhering to an electrostatic image support. . Another object of the present invention is to provide a static developer for use as a one-component developer that has excellent triboelectric charging properties, is non-cohesive, has high fluidity, and is capable of forming excellent visible images without fogging. The present invention provides a toner for developing a charge image.

The above-mentioned objects of the present invention are achieved by a toner containing a compound represented by the following general formula [1] (hereinafter referred to as the compound of the present invention).

General formula [1] In general formula [1], R. R' is a Japanese atom, a nitro group, a cyano group, a carboxy group, a hydroxy group, a mercapto group, or a sulfo group, R' is a hydroxy group, an alkoxy group, or an amino group, m is 1 or 2, and n is 1 to 5 represents an integer.

However, at least one of -COR' in the general formula is R''C
f) In the ortho position. Also, excluding the case where the compound represented by the general formula [1] is phthalic acid. The alkoxy group and the amino group may be unsubstituted or may have any substituent.

Typical substituents for alkoxy groups include halogen atoms,
Typical substituents for the amino group include a hydroxy group, an amino group, and a carboxy group, and typical substituents for the amino group include an alkyl group and an aryl group. Next, typical examples of the above-mentioned compounds will be given.

Exemplary compound 1) 2,4-dinitrobenzoic acid 20-cyanobenzoic acid 32-chloro-3,5-dinitrobenzoic acid 43,4-dibromo-0-phthalic acid 5) Thiosalicylic acid 6} Sahuatylic acid 73-cyano-0 -Phthalic acid 82,3-dihydroxybenzamide 90-Methyl fluorobenzoate 00) 2-sulfobenzoic acid In the present invention, a toner and a two-component developer comprising a resin containing a colorant, a charge polarity control agent, etc. The compound of the present invention is contained in a resin in a toner of a one-component developer in which fine magnetic powder is dispersed in the toner particles of the component developer.

The electrostatic image developing toner of the present invention is as described above,
Through normal triboelectrification operations, it is easily charged to a sufficient amount of charge necessary for developing an electrostatic image, but the amount of charge is stable at a lower value than that of a product that does not contain the compound of the present invention. For example, in the toner of the two-component developer according to the present invention, the amount of charge hardly changes due to changes in the concentration in the developer, and can maintain a substantially constant state. In other words, since the toner of the present invention mainly contains the compound of the present invention in the resin that constitutes its surface layer and thus forms the surface to be rubbed, the amount of saturation charge due to triboelectric charging of the toner is smaller than the electrostatic charge image. It has the property of being controlled to a substantially constant size suitable for development, and therefore, even if an excess charge is generated due to friction, the rate of attenuation and disappearance of the excess charge is fast and it immediately reaches a substantially constant saturated charging state. Moreover, in this saturated charging state, the charge retention force is large, the rate of attenuation and loss of charge is low, and the amount of charge on the entire toner becomes uniform. Nobu The compound of the present invention is 0.5 to 100 parts by weight of resin.
It is generally contained in a proportion of 10 parts by weight, preferably 1 to 5 parts by weight. The amount should be adjusted depending on the type and amount of the magnetic material, etc., and the type and amount of other resins as physical property improvers for the main resin, such as linear polyalkane polymer substances.

However, if the content of the compound of the present invention is too small, it will be difficult to obtain the above-mentioned effects, and if the content is too large, the charge retention performance will decrease and the saturation charge amount will decrease, and the physical properties of the resin will change, so storage This can lead to a decline in sexuality. In general, aromatic carboxylic acids have sublimation properties and are therefore difficult to handle; however, the sublimation temperature of the compound of the present invention is relatively high, and the maximum temperature in the manufacturing process of the toner of the present invention is lower than that of the resin. Since the temperature is below the temperature of the kneading process with other substances, handling of the compound of the present invention is not restricted by its sublimation property.

In addition, it is desirable that the resin be inexpensive and have low toxicity (of course). In the present invention, examples of the resin containing the compound of the present invention include styrene resin, acrylic resin, epoxy resin, polyester resin, polyamide resin, and polyolefin resin. Although resins made of various homopolymers, copolymers, or blend polymers can be used, resins having a phenyl ring in the molecule are particularly suitable.

In such a resin, the above-described favorable effects of the compound of the present invention can be reliably obtained, and the reason for this is thought to be that the phenyl ring of the compound has orientation with respect to the phenyl ring of the resin. According to the toner powder for developing an electrostatic image of the present invention, the toner powder is charged to a stable state of a charge amount suitable for developing an electrostatic image by friction, and the charge amount hardly changes due to fluctuations in conditions during the friction process. For example, by applying the present invention to toner of a two-component developer,
Even if the toner concentration of the developer changes as development is repeated, the amount of charge on the toner remains substantially constant, and the charge distribution throughout the developer is uniform, so all developed images are the same. As a result, stable development can be achieved and the life of the developer can be extended.

In addition, even if there is a slight change in the toner composition or manufacturing conditions, the charge amount of the toner will not substantially change, and therefore there will be no instability in performance due to so-called variations, so various conditions can be tolerated. The range is widened, and as a result, it is possible to easily produce a toner for developing electrostatic images having the required performance. Furthermore, it is possible to add some dyes and the like to the toner of the present invention, which have conventionally been desired to be added because they impart desirable characteristics, but could not be added because they have the effect of changing the amount of charge of the toner. becomes. This is because changes in the amount of charge caused by such additive substances are largely suppressed in the toner of the present invention, and therefore, desired characteristics can be effectively utilized by the additive substances. Further, since the saturation charge amount of the toner of the present invention is relatively low, all drawbacks caused by excessively charged particles are eliminated.

That is, according to the two-component developer composed of the toner according to the present invention, a developed image can have sufficient density, and the carrier does not adhere to the electrostatic image support.
Furthermore, according to the one-component developer according to the present invention, toner cohesion is small and sufficient fluidity is obtained, so that the required development can be sufficiently achieved and an excellent visible image without fogging can be formed. be done. Examples of the present invention will be described below, but the scope of the present invention is not limited by these.

Note that [parts] represent parts by weight. Example 1 After premixing the above mixture, it was kneaded in a two-roll mill, and the particles after cooling were crushed and classified to produce a toner for a two-component developer having an average particle size of 15 μm.

This toner was mixed with a carrier made of iron powder to prepare a two-component developer (sample of the present invention) with a toner concentration of 5%. In addition, a comparative sample was produced in exactly the same manner except that exemplified compound (5) was not included.

These samples were tested using U-Bix 2000R.
[Manufactured by Konishiroku Photo Industry Co., Ltd.] 10,000 live-action tests
When the sample of the present invention was repeated, the image density of the visible image obtained from the sample of the present invention was substantially uniform, there was no background smudge, and the loss of carrier was small.

On the other hand, the image density of the visible image obtained from the comparative sample decreased as the number of copies increased, scumming occurred, and the amount of carrier was also significantly reduced. Example 2 After premixing the above mixture, it was kneaded using a twin-screw extruder, and after cooling, the obtained agglomerates were crushed, classified, and granulated to give an average particle size of 15 μm.
A toner for a two-component developer was produced.

This toner was mixed with a carrier made of iron powder to produce two-component developers (samples of the present invention) having toner concentrations of 8%, 5%, and 2%. Furthermore, a comparative two-component developer (comparative sample) was produced in the same manner as above except that a compound other than the exemplified compound was added, or in the same manner as above except that the exemplified compound was not added.

The relationship between the amount of charge and the concentration of each sample was investigated, and the results are shown in Table 1.

Furthermore, a sample of a developer with a toner concentration of 5% was loaded into U-Bix V (manufactured by Konishiroku Photo Industry Co., Ltd.), and 5,000 actual copying tests were conducted. The ratio, reproducibility of fine lines, occurrence of fog, and weight loss of carrier per 1k9 of developer were investigated, and the results are shown in Table 1. Image density, fog, and fine line reproducibility were evaluated as ×: bad, Δ: somewhat good, ○: good, and ◎: very good.

From the results in Table 1, it can be seen that sample wash 1 (comparative sample) shows a significant decrease in copied image density, fogging, and increase in carrier weight loss as the number of copies increases, and sample wash 2 (comparative sample) shows that the toner is not charged. While the reproducibility of fine lines was worse than desired due to non-uniformity, samples 3 to 5 (samples of the present invention) did not have this problem.

Example 3 The above mixture was kneaded in a pressurized kneader, and after cooling, the resulting particles were crushed, further aerosolized in hot air at 250°C, the toner intermediate was heat-treated, and then rapidly cooled. After collecting, the obtained collected material was classified to produce a magnetic toner (sample of the present invention) having an average particle size of 18 μm.

Furthermore, a magnetic toner (comparative sample) was produced in exactly the same manner as above except that the exemplified compound (self) was not used. These magnetic toners were used in a modified U-Bix 750 machine [
[manufactured by Konishi Roku Photo Industry Co., Ltd.] was used to conduct a 20,000-shot test.

In the sample of the present invention, a clear copy image with no image stains was obtained even after 20,000 copies, whereas in the comparison sample, stains were noticeable on the copied image and the image became unclear. Example 4 The mixture was kneaded in a pressurized kneader, cooled, and pulverized to produce a sample of a one-component developer with an average particle size of 12 μm (sample of the present invention).
It was created.

A sample of a one-component developer (comparative sample) was prepared in exactly the same manner as above except that the exemplified compound was removed from the mixture.

Using these samples, in an electrophotographic copying machine equipped with a developing device for one-component developer, an electrostatic charge image was formed on the zinc oxide photoreceptor, and the repeated copying test was repeated 2,000 times in a row for development. The results shown in Table 2 were obtained.

Claims (1)

[Scope of Claims] 1. A toner for developing electrostatic images, characterized by containing a compound represented by the following general formula [I] dispersed in a resin. General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R and R'' are halogen atoms, nitro groups, cyano groups,
Carboxy group, hydroxy group, mercapto group or sulfo group, R' is hydroxy group, alkoxy group or amino group, m is 1 or 2 and n is an integer from 1 to 5. However, at least one of -COR' is at the ortho position of -R''. This excludes the case where the compound represented by the general formula [I] is phthalic acid.]