JP3108827B2 - Developer for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer for developing an electrostatic image used in an image forming method such as an electrophotographic method, an electrostatic recording method and an electrostatic printing method.

[0002]

2. Description of the Related Art Conventionally, electrophotography has been disclosed in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910.
Numerous methods are known as described in Japanese Patent Application Laid-Open Publication No. Hei. Generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means, and then the latent image is developed using toner, and if necessary, a toner image is formed on a transfer material such as paper. Is transferred, and then fixed by heating, pressure, heating and pressurizing, or solvent vapor to obtain a toner image.

Various methods and apparatuses have been developed for fixing the toner image to a sheet such as paper, which is the above-mentioned final step, but the most common method at present is a pressure heating method using a heat roller.

In the pressure heating method using a heating roller, the toner image is fixed by passing the surface of the heat roller having a releasing property to the toner and the toner image surface of the fixing sheet under pressure while passing the fixing sheet. It is what you do. In this method, since the surface of the heat roller and the toner image on the sheet to be fixed come into contact with each other under pressure, the thermal efficiency at the time of fusing the toner image onto the sheet to be fixed is extremely good, and the fixing can be performed quickly. And is very effective in high-speed electrophotographic copying machines.

In such a fixing method, use of a binder resin containing an acid component in order to improve fixability has been proposed in JP-A-55-134861. However, a toner using such a binder resin tends to cause insufficient charging under high humidity and excessive charging under low humidity, and is easily affected by environmental fluctuation. Further, fog is likely to occur and the image density may be low.

On the other hand, acid anhydrides have a function of improving the chargeability, and examples of applying a resin containing an acid anhydride are disclosed in JP-A-59-139053 and JP-A-62-280758.
No. 1993. These methods employ a method of diluting a polymer having acid anhydride units at a high density into a binder resin. In these methods, it is necessary to uniformly disperse the acid anhydride-containing resin in the binder resin, and if not dispersed well, the toner particles become non-uniform in charge, fogging is likely to occur, and adversely affects the developability. .

Therefore, dispersing and diluting the units of the acid anhydride into the polymer chains in the binder resin by copolymerization can solve the problem of dispersion and provide toner particles with uniform chargeability. . JP-A-61-123856,
These toners have been proposed in, for example, JP-A-61-123857. These toners have good fixability, offset resistance, and developability.

However, when such a toner is applied to a high-speed copying machine under low humidity, the toner may be excessively charged, causing fog and a decrease in density.

Further, in recent years, digitalization of the copying machine and reduction in the particle size of the toner have been demanded to increase the functions of the copying machine and improve the quality of the copied image.

[0010] However, in the multifunctional copying machine, for example, a part of an image is erased by exposure or the like, and
Then, in a function such as multiplex multicolor copying in which another image is inserted into the portion or a frame around the periphery of the copy paper, fogging occurs in a portion of the image to be removed in white.

That is, when a potential opposite to the latent image potential with respect to the development reference potential is applied by strong light such as an LED or a fuse lamp to erase an image, there is a problem that the fog tends to occur in that portion. .

[0012] Further, even if the resolution and sharpness of an image can be increased by digitization and reduction in the particle diameter of the toner, various problems arise.

The first problem is the fogging problem described above. By reducing the particle size of the toner, the surface area of the toner is increased, and therefore, the width of the charge amount distribution is increased, and fogging is likely to occur. Further, as the toner surface area increases, the charging characteristics of the toner are more likely to be affected by the environment.

Further, when the particle diameter of the toner is reduced, it is apparent that the dispersion state of the polar substance and the colorant greatly affects the chargeability of the toner.

[0015] In recent digital copiers,
In a photographic image containing characters, the characters of the copy image are required to be clear, and the photographic image is required to have a density gradation property faithful to a document. In general, in copying a photographic image containing characters, if the line density is increased to make the characters clear, not only the density gradation of the photographic image is impaired, but also the halftone portion becomes a very rough image. Conversely, if an attempt is made to improve the density gradation of a photographic image, the density of the character line will decrease, and the sharpness will deteriorate.

In recent years, the density gradation has been improved to some extent by reading the image density and converting it into digital data. However, it is still not enough.

This is largely due to the developing characteristics of the developer. That is, the developing potential (difference between the potential of the photosensitive member and the potential of the developer carrying member) does not have a linear relationship with the image density.
As shown in (solid line), a curve with a low developing potential is convex downward, and a curve with a high developing potential is convex upward. Therefore, in the halftone area, a slight change in the development potential causes a very large change in image density. This makes it difficult to obtain a sufficiently satisfactory density gradation.

Normally, in order to copy a line image and maintain its sharpness, since the edge effect is affected, the maximum image density in a solid image portion which is hardly affected by the edge effect is 1.30.
A degree is sufficient.

However, in a photographic image, the maximum density of the photograph itself largely depends on its surface glossiness, which is 1.9.
It is very high, from 0 to 2.00. Therefore, even when the glossiness of the surface is suppressed in copying a photographic image, the image area is large and the density is not increased by the edge effect. Therefore, the maximum image density in the solid image portion is 1.4 to About 1.5 is necessary.

Therefore, the developing potential and the image density are set to a primary (linear) relationship, and the maximum image density is set to 1.4 to
A value of 1.5 is very important for copying photographic images with text.

For this purpose, it is important to control the charge amount of the toner as uniformly as possible.

Japanese Patent Application Laid-Open No. S58-58158 discloses a method for preventing an increase in the charge amount of toner and stabilizing the charge amount by using conductive powder.
-66951, JP-A-59-168458-16
No. 8460, JP-A-59-170847 and the like disclose methods using conductive zinc oxide and tin oxide. According to these methods, the maximum image density is 1.3
In a system using a large amount of conductive powder, the density is 1.4 or more, but the density gradation is poor. It is well known that the charge amount of toner has a charge amount distribution, and the distribution width increases as the charge amount of toner increases. That is, in these methods, the amount of charge is reduced and the distribution of the charge amount is sharpened by attaching conductive powder to the toner having a high charge amount. However, even with these methods, a satisfactory image cannot be obtained in copying a photographic image containing characters.

Further, a non-magnetic toner having a volume average particle diameter of 5 to 20 μm is mixed with a fine powder having a volume average particle diameter of 1/20 to 1/2 to stabilize the toner replenishing property. JP-A-61-183664 discloses a method for forming a uniform toner layer and obtaining a sufficient amount of triboelectric charge.
According to this method, in the color toner, the toner replenishment can be stabilized to form a thin layer on the developer carrier, and the charge amount can be increased. However, in the magnetic toner, as described above,
When the charge amount distribution is sharpened and further copied, a maximum density of 1.4 to 1.5 and a sufficient density gradation cannot be obtained.

Japanese Patent Application Laid-Open No. Sho 60-32060 discloses a method for removing paper powder, ozone adducts and the like generated or adhered to the surface of a photoreceptor by using two kinds of inorganic powders. .

Further, in Japanese Patent Application Laid-Open No. 2-110475, two kinds of inorganic fine powders are used for a toner using a metal-crosslinked styrene acrylic resin to form paper powder, ozone There is disclosed a method for improving removal of adducts and the like and improvement of toner fixability, toner scattering under high temperature and high humidity, image deletion, and image density reduction.

Although these methods can certainly remove the deposits on the photoreceptor, they have not yet solved the various problems described above.

Further, Japanese Patent Application Laid-Open No. 61-236559,
JP-A-63-2073 discloses a method for improving the chargeability of a toner by using cerium oxide particles to dissociate aggregated silica and a toner mass. In this method, the chargeability is certainly improved, but when an organic photoreceptor is used, the effect of the cerium oxide as a polishing agent is large, so that the resin of the photoreceptor surface layer is gradually scraped off when copying is continued, As a result, the performance of the photoreceptor deteriorates, and the quality of the copied image gradually deteriorates.

At present, there is no developer capable of solving all of the above various problems.

[0029]

SUMMARY OF THE INVENTION An object of the present invention is to provide a developer for developing an electrostatic image used in an image forming method using an organic photoreceptor, which solves the above-mentioned problems.

An object of the present invention is to provide a developer for developing an electrostatic image capable of obtaining a high-density copy image without fogging without impairing the fixing property.

An object of the present invention is to provide a developer for developing an electrostatic charge image which gives a good image even under low humidity and high humidity without being affected by environmental changes.

An object of the present invention is to provide a developer for developing an electrostatic image which gives a good image stably even in a high-speed machine and has a wide range of applicable models.

It is an object of the present invention to provide a developer for developing an electrostatic charge image which is excellent in durability, has a high image density even when used continuously for a long time, and has no fog on a white background and can obtain a copy image. is there.

It is an object of the present invention to provide a photographic image containing characters, which is excellent in resolution and fine line reproducibility, in which the characters of the copied image are clear, and the photographic image has a density gradation faithful to the original. An object of the present invention is to provide a developer for developing a charge image.

An object of the present invention is to simultaneously achieve a uniform coating of a magnetic toner on a developer carrying member and a uniform and stable charging of the magnetic toner on the developer carrying member over a long period of time. An object of the present invention is to provide a developer for developing an electrostatic charge image that makes flying of a magnetic toner more efficient.

[0036]

According to the present invention, the weight average particle diameter (t-D4) is ₄ to 12 .mu.m, the number average particle diameter (t-D1) is ₁ to 10 .mu.m, tD ₄ )
An insulating magnetic toner having a ratio of (t-D ₁ ) of 1.01-2, a fluidizing agent, and a weight-average particle diameter (m-D ₄ ) of 0.6-5 μm; a diameter (m-D ₁₎ is _{0.5~4μm, (m-D 4)} / (m-D 1) the ratio of is _{1.1~2.4, (m-D 4)} / ( m-D
₁ ) contains a metal oxide powder having a ratio equal to or greater than the ratio of (t-D ₄ ) / (t-D ₁ ), and the compounding amount of the metal oxide powder is A developer for developing an electrostatic image, wherein the amount is 2 to 8 times the compounding amount of

As described above, it is well known that the charge amount of toner has a charge amount distribution. In the case of a one-component magnetic toner, this distribution state is affected by the distribution state of a material constituting the toner, for example, a magnetic substance and a colorant, and the particle size distribution of the toner. When the materials constituting the toner are uniformly dispersed, the charge amount distribution is mainly affected by the particle size distribution of the toner. Generally, a toner having a small particle size has a large charge amount, and a toner having a large particle size has a small charge amount. Also, the distribution width of the toner having a larger charge amount is generally wider as the charge amount of the toner is larger, and narrower as the charge amount of the toner is small.

As a method of sharpening the charge amount distribution by using a toner having a high charge amount, there is a method of lowering the charge amount by attaching conductive powder to the toner as described above. Although the properties are good, the concentration is not sufficient at the maximum concentration. The present inventors considered the reason for this as follows.

In the method of lowering the charge amount by attaching the conductive powder to the toner, the conductive powder itself is slightly charged, but does not uniformly adhere to the toner. It is thought that more adherence is caused by the mechanical force.

In charging by friction between toners, since the surfaces of the toners in contact with each other are charged, the oppositely charged charges are distributed on the same toner surface. Therefore, it is considered that the toner having a small particle diameter has a larger surface area, and thus easily adheres regardless of the charging polarity of the conductive powder. Further, the toner having a smaller particle diameter has a larger surface area, and the amount of charge per unit weight increases. Therefore, when charged with the opposite polarity, fog appears as a white background portion when copied. Therefore, fog is improved by putting the conductive powder into the toner and attaching it to the opposite polarity toner having a small particle size.

However, a toner having a small particle diameter to which conductive powder having a large effect of lowering the charge amount adheres is selectively developed because the charge amount has decreased. Therefore, although the density gradation is improved, the maximum image density is small because the toner having a small particle size is melted and spread by fixing and the area covering the fixing support is smaller than that of the toner having a large particle size. Is slightly inferior to that of the toner having a large particle size.

Further, since only toner having a small particle size is selectively developed, halftone roughness is good at the beginning, but if copying is continued, the toner particle size in the developing device becomes large and deteriorates.

The inventors of the present invention have conducted intensive studies and have found that the contact between the toner and the metal oxide causes the charge amount of the toner having a low charge amount in the charge amount distribution to be opposite to the decrease in the charge amount of the toner. Found a way to raise In other words, instead of attaching a metal oxide to a toner and developing the toner, the toner and the metal oxide are contact-frictionally charged in a developing device to obtain a uniformly charged toner.

For a toner having a certain particle size, a very small metal oxide powder has a very large image force on the toner itself. Therefore, even if a shear force is applied to the toner, the toner remains attached to the toner, and thus has an effect of reducing the charge amount of the toner as described above. However, the metal oxide powder having a certain size for a toner having a certain particle size adheres to the toner and, due to the shearing force received in the developing device, separates, so that the number of times of contact with the toner increases. Conversely, the charge amount of the toner increases.

The present inventors have conducted detailed studies based on this concept and have ascertained the following.

The width of the particle size distribution of the metal oxide powder [(m−D
₄ ) / (m−D ₁ )] is the width [t−D] of the particle size distribution of the toner.
₄ ) / (t-D ₁ )], or a wider one can obtain uniform charging properties. That is, for a toner having a certain particle size, a metal oxide having a certain particle size in a certain range has a capability of significantly increasing the charge amount of the toner. Therefore, the width of the particle size distribution of the metal oxide powder is preferably wider than the width of the particle size distribution of the toner.

Further, it has been found that it is important that the developer satisfies the following constitutional requirements.

The toner has a weight average diameter of 4 to 12 μm, a number average diameter of 1 to 10 μm, and a distribution width [(t−D ₄ ) / (t−D ₁ )] of 1.01 to 2. There is.

Use of a fluidizing agent.

The weight average particle size of the metal oxide powder is 0.6
-5 μm, the number average particle diameter is 0.5-4 μm, and the distribution width [(m−D ₄ ) / (m−D ₁ )] is 1.
1 to 2.3.

These are due to the following reasons.

When the weight average particle diameter of the toner exceeds 12 μm, the halftone image becomes rough and uneven.
If it is less than μm, fog on a white background portion is poor.

When the toner particle size exceeds 12 μm, a metal oxide powder having a large particle size is required to increase the charge amount of the toner. The metal oxide powder having a large particle size is not developed and accumulates in the vicinity of the developer carrier. Therefore, a large amount of metal oxide powder having a large particle diameter is present on the developer carrier, and the amount of toner to be developed is reduced.
White streaks appear on the image, the image density decreases, and the roughness of the halftone image deteriorates.

When the toner particle size is less than 4 μm, in order to increase the charge amount of the toner, in terms of the particle size,
What is necessary is just to make the particle diameter of a metal oxide powder small. However, with such a particle size, the surface area of the toner increases, so that unless a large amount of metal oxide powder is used, the chargeability of the toner cannot be kept uniform. When a large amount of metal oxide powder having a small particle size is used, the metal oxide powder passes through the cleaning blade, that is, cleaning failure occurs, or the metal oxide powder gradually scrapes the resin layer of the organic photoreceptor. As a result, the sensitivity of the photoreceptor deteriorates, and the copy image deteriorates, for example, the image density decreases.

The width of the particle size distribution of the toner [(t−D ₄ ) /
When (t−D ₁ )] is larger than 2, the spread of the charge amount distribution due to the particle size distribution increases as described above. Therefore, even when the metal oxide powder according to the present invention is used, sufficient uniform chargeability is obtained. I can't get it.

Further, in the absence of a fluidizing agent, the fluidity of the one-component magnetic toner used in the present invention is remarkably reduced, which also causes poor charging. In the absence of a fluidizing agent, the fluidity of the waste developer in the cleaning unit is significantly reduced, so that the shaving amount of the photoconductor surface layer resin increases,
Deterioration of the image is caused by scratching.

When a metal oxide powder having a weight average particle size of more than 5 μm is used, the chargeability of the toner is improved to some extent. In the developing unit,
As the amount of metal oxide powder accumulated on the developer carrier increases, the quality of the copied image gradually decreases. When the weight average diameter is smaller than 0.6 μm, the chargeability of the toner is reduced as described above, which does not meet the purpose of the present invention. Further, the ratio of _{(m-D 4) / (} m-D 1) is larger than 2.4, the particle size distribution is too wide, that too fine particle size and, most things too coarse particle size It is not preferred.

Further, in the toner and the metal oxide powder according to the present invention, it is preferable that the metal oxide powder is hardly charged or is charged to a polarity opposite to that of the toner. In the present invention, instead of using metal powder to adhere to the toner, since the purpose is to increase the charge by frictional charging,
When the same polarity is used, not only does the amount of charge of the toner decrease, but also the frictional charging speed decreases, the initial copy density is low, and as the copy is continued, the density gradually increases. A rising phenomenon appears.

Further, when a metal oxide powder charged to the opposite polarity to the toner is used, the toner having a small particle size and the metal oxide powder having a small particle size interact with each other when mixed. That is, those having a large charge amount per unit weight and having a large action surface area act on each other because of opposite polarities. Therefore, the toner having a large particle size and the metal oxide powder having a large particle size interact with each other. In the same developing unit, the combination of the toner having a small particle diameter and the metal oxide powder is less susceptible to the frictional charging due to the stirring than the combination of the large toners. This is because when subjected to shearing force due to agitation, small ones often slip through without receiving the shearing force. In addition, the amount of charge given to the toner having a small particle size by the metal oxide powder having a small particle size is small because the total charge amount of the metal oxide powder is small. Conversely, in the case of a combination of a metal oxide powder having a large particle size and a toner having a large particle size, the charge amount was low depending on the particle size because the total charge amount of the metal oxide powder was also affected by the contact charging due to stirring. The charge amount of a toner having a large particle diameter increases,
In the developing ability, the difference in toner particle diameter disappeared, that is, the phenomenon of selective development described above did not occur.

From the above, the particle size of the toner and the particle size of the metal oxide powder are also important. However, considering the charging mechanism by the interaction, the particle size distribution width of the toner and the particle size of the metal oxide powder are considered. The relationship between the distribution width and the relationship between the particle size of the toner and the particle size of the metal oxide powder become very important.

As a result of a detailed study, it is preferable that the toner and the metal oxide powder satisfy the following relationship with respect to the above, since they can be more effectively exhibited.

[0062]

(Equation 1)

[0063]

(Equation 2) Only when the developer satisfies the above-mentioned constitutional requirements can the above-mentioned various problems be solved. Further, in the developer of the present invention, it is possible to prevent the phenomenon that only the toner having a small particle diameter described above is selectively developed and consumed, so that even if copying is continued, halftone There is no roughness and excellent reproducibility of fine lines, and density gradation and maximum image density can be sufficiently satisfied.

Further, it is important that the compounding amount of the metal oxide powder is 2 to 8 times the compounding amount of the fluidizing agent in order to maintain good developing characteristics of the developer and suppress selective development. is there. Further, the constitution of a preferred developer for achieving the object in the present invention will be described in detail below.

Examples of the binder resin used in the present invention include vinyl resins, polyester resins, and epoxy resins. Among them, vinyl resins and polyester resins are more preferable in terms of charging characteristics and fixing properties.

In a more preferred embodiment, the vinyl resin has an acid anhydride group in order to further improve not only the fixing property but also the charging property of the toner, and the total acid value of the vinyl resin. (A) is 2 to 100 mgKOH / g, preferably 5 to 70 mgKOH / g, more preferably 5 to 70 mgKOH / g.
It is preferable to use one having a concentration of 50 mgKOH / g.

When the total acid value (A) is less than 2 mgKOH / g, good fixability is difficult to obtain, and when it exceeds 100 mgKOH / g, it becomes difficult to control the chargeability of the toner.

The components that give an acid value include a carboxyl group and an acid anhydride group, and these functional groups have a large effect on the chargeability of the toner. For example, when there is a carboxyl group in the polymer chain, there is a weak negative charge imparting ability.
However, when the abundance of the carboxyl group increases, the hydrophilicity of the resin increases, and the charge is released to moisture in the air. This tendency becomes remarkable as the number of carboxyl groups increases.

On the other hand, the acid anhydride group has a negative charge imparting ability, but has no or extremely low ability to release electric charge.

Therefore, the ratio of these functional groups is important for stabilizing the chargeability of the toner. The carboxyl group works not only for releasing charges but also for imparting charge.

On the other hand, the acid anhydride group works particularly effectively only for imparting chargeability. When a large number of carboxyl groups are present, charge release is increased, the charge amount of the toner becomes insufficient, and it becomes difficult to obtain a sufficient image density. This tendency becomes remarkable under high humidity.

On the other hand, when there are many acid anhydride groups, the charge amount of the toner becomes excessive, and the fog is increased.
In particular, under a low humidity, this tendency becomes stronger and causes a decrease in image density.

The presence of these functional groups at an appropriate ratio can balance the provision of charge and the release of charge, stabilizing the chargeability of the toner, and affecting the chargeability due to environmental fluctuations. Can be minimized.

That is, while the charge is imparted in the presence of the acid anhydride group, the charge is released in the presence of the carboxyl group,
Excessive charging of the toner can be prevented.

For that purpose, it is important that the total acid value (B) derived from the acid anhydride group is 6 mgKOH / g or less. If it exceeds 6 mgKOH / g, the toner is liable to be excessively charged, which may cause a decrease in density and fog under low humidity.

Further, it is preferable that the total acid value (B) derived from the acid anhydride group is 60% or less of the total acid value (A) of the whole binder resin. If it exceeds 60%, the balance between the application of electric charge and the release of electric charge will not be balanced, the ability to apply electric charge will be better, and the toner will be more likely to be overcharged.

The following are examples of vinyl monomers that give an acid value to the binder resin.

For example, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid, mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride, alkenyl succinic anhydride Unsaturated dibasic acid anhydrides such as those; methyl maleate half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid ethyl half ester, citraconic acid butyl half ester, methyl itaconate Half esters of unsaturated dibasic acids such as half ester, methyl alkenyl succinate half ester, methyl half fumarate ester and methyl half ester of mesaconic acid; and unsaturated dibasic acid esters such as dimethyl maleic acid and dimethyl fumaric acid. It is.

Acrylic acid, methacrylic acid, crotonic acid,
Α, β-unsaturated acids such as cinnamic acid; crotonic anhydride,
Α, β-unsaturated acid anhydrides such as cinnamic anhydride;
anhydrides of β-unsaturated acids and lower fatty acids; alkenyl malonic acid, alkenyl glutaric acid, alkenyl adipic acid,
These acid anhydrides and their monoesters are mentioned.

Among these, maleic acid, fumaric acid,
Monoesters of α, β-unsaturated dibasic acids having a structure such as succinic acid are particularly preferred.

Further, examples of the comonomer of the vinyl copolymer include the following.

For example, styrene, o-methylstyrene, m
-Methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene,
2,4-dimethylstyrene, pn-butylstyrene,
styrene and its derivatives such as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene; ethylene; Ethylenically unsaturated monoolefins such as propylene, butylene and isobutylene; unsaturated polyenes such as butadiene;
Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl ester acids such as vinyl acetate, vinyl propionate and vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylic acid α-methylene aliphatic monomers such as n-butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate Carboxylic esters;
Methyl acrylate, ethyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, propyl acrylate,
Acrylic esters such as n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate and phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N
N- such as vinylindole and N-vinylpyrrolidone
Vinyl compounds; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; esters of the above-mentioned α, β-unsaturated acids and diesters of dibasic acids. These vinyl monomers are used alone or in combination of two or more.

Of these, a combination of monomers that results in a styrene copolymer or a styrene-acrylic copolymer is preferred.

If necessary, the polymer may be crosslinked with a crosslinking monomer as exemplified below.

Examples of the aromatic divinyl compound include divinylbenzene and divinylnaphthalene; examples of the diacrylate compound linked by an alkyl chain include:
Ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and the above compounds Diacrylate compounds linked by an alkyl chain containing an ether bond, for example, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and methacrylate Include those obtained by changing the over preparative; e.g. diacrylate compounds linked with a chain containing an aromatic group and an ether bond, polyoxyethylene (2)
-2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate, and acrylates of the above compounds were replaced with methacrylates. And polyester-type diacrylate compounds, for example, trade name MANDA (Nippon Kayaku). Examples of polyfunctional crosslinking agents include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylol methanetetraacrylate,
Oligoester acrylates and those obtained by replacing the acrylates of the above compounds with methacrylates; triallyl cyanurate, triallyl trimellitate;

[0086] These cross-linking agents may be used in combination with other monomer components 10
0.01 to 5% by weight (more preferably 0.03 to 3% by weight) can be used with respect to 0% by weight.

Among these crosslinkable monomers, aromatic divinyl compounds (particularly divinylbenzene), chains containing an aromatic group and an ether bond are preferably used from the viewpoint of fixability and offset resistance to a resin for toner. Diacrylate compounds tied together.

In the present invention, a vinyl monomer homopolymer or copolymer, polyester, polyurethane, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic carbonized A hydrogen resin, an aromatic petroleum resin, or the like can be used by being mixed with the binder resin described above as necessary.

When two or more resins are mixed and used as a binder resin, as a more preferred form, those having different molecular weights are preferably mixed at an appropriate ratio.

The glass transition temperature of this binder resin is 45 to 8
0 ° C., preferably 55-70 ° C., and a number average molecular weight M
n2,500-50,000, weight average molecular weight Mw1
It is preferably from 000 to 1,000,000.

The method for synthesizing the vinyl binder resin according to the present invention includes bulk polymerization, solution polymerization, suspension polymerization, and the like.
A polymerization method such as an emulsion polymerization method can be used. When a carboxylic acid monomer or an acid anhydride monomer is used, it is preferable to use a bulk polymerization method or a solution polymerization method due to the nature of the monomer.

As an example, the following method can be mentioned.
A vinyl copolymer can be obtained by a bulk polymerization method or a solution polymerization method using a monomer such as dicarboxylic acid, dicarboxylic anhydride or dicarboxylic acid monoester. In the solution polymerization method, the dicarboxylic acid or dicarboxylic acid monoester unit can be partially dehydrated by devising the conditions for distilling off the dicarboxylic acid or dicarboxylic acid monoester unit at the time of distilling off the solvent. Furthermore, the vinyl copolymer obtained by the bulk polymerization method or the solution polymerization method can be further dehydrated by heat treatment. The acid anhydride can also be partially esterified with a compound such as an alcohol.

Conversely, the vinyl copolymer thus obtained can be hydrolyzed to open the acid anhydride group to partially convert it into a dicarboxylic acid.

On the other hand, using a dicarboxylic acid monoester monomer, a vinyl copolymer obtained by a suspension polymerization method or an emulsion polymerization method is dehydrated by heat treatment and ring opening by hydrolysis to convert the dicarboxylic acid to a dicarboxylic acid. Can be obtained. By using a method of dissolving a vinyl copolymer obtained by a bulk polymerization method or a solution polymerization method in a monomer and then obtaining a vinyl polymer or a copolymer by a suspension polymerization method or an emulsion polymerization method, Part of the acid anhydride can be opened to obtain a dicarboxylic acid unit. At the time of polymerization, another resin may be mixed into the monomer, and the obtained resin can be converted to an acid anhydride by a heat treatment, or esterified by a ring-opening alcohol treatment of the acid anhydride by a weak alkaline water treatment.

Since dicarboxylic acid and dicarboxylic anhydride monomers have strong alternating polymerizability, the following method is preferred for obtaining a vinyl copolymer in which functional groups such as anhydride and dicarboxylic acid are randomly dispersed. one of. This is a method in which a vinyl copolymer is obtained by a solution polymerization method using a dicarboxylic acid monoester monomer, and the vinyl copolymer is dissolved in the monomer to obtain a binder resin by a suspension polymerization method. In this method, the entire or dicarboxylic acid monoester moiety can be de-alcoholized and ring-closed and dehydrated depending on the processing conditions when the solvent is distilled off after the solution polymerization, and an acid anhydride can be obtained. At the time of suspension polymerization, the acid anhydride group is hydrolyzed and ring-opened to obtain a dicarboxylic acid.

In the formation of an acid anhydride in a polymer, the generation or disappearance of the acid anhydride can be confirmed because the infrared absorption of carbonyl shifts to a higher wave number side than in the case of an acid or ester.

In the thus obtained binder resin, a carboxyl group, an anhydride group and a dicarboxylic acid group are uniformly dispersed in the binder resin, so that good chargeability can be imparted to the toner.

The composition of the polyester resin used in the present invention is as follows.

The polyester resin used in the present invention comprises:
45 to 55 mol% of all components are alcohol components,
55 to 45 mol% is an acid component.

Examples of the alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol,
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and a bisphenol derivative represented by the formula (a);

[0101]

Embedded image A diol represented by the formula (b);

[0102]

Embedded image And polyhydric alcohols such as glycerin, sorbit, and sorbitan.

The divalent carboxylic acid containing 50 mol% or more of the total acid component includes benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride or anhydrides thereof; succinic acid, adipic acid, sebacine Alkyl dicarboxylic acids such as acid and azelaic acid or anhydrides thereof, and succinic acid or anhydrides further substituted with an alkyl group having 6 to 18 carbon atoms; non-succinic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid; Saturated dicarboxylic acids or anhydrides thereof and the like, and as the trivalent or higher carboxylic acid, trimellitic acid, pyromellitic acid,
Benzophenone tetracarboxylic acid and its anhydride are exemplified.

The alcohol component of the polyester resin particularly preferred in the practice of the present invention is a bisphenol derivative represented by the above formula (a), and the acid component is phthalic acid, terephthalic acid, isophthalic acid or its anhydride, or succinic acid. And dicarboxylic acids such as n-dodecenylsuccinic acid or anhydride thereof, fumaric acid, maleic acid and maleic anhydride; and trimellitic acid or tricarboxylic acids of anhydride thereof.

This is because the polyester resin obtained with these acids and alcohols has good fixability as a toner for fixing with a heat roller, and has excellent offset resistance.

The acid value is 90 or less, preferably 50 or less.
Hereinafter, the OH value is desirably 50 or less, preferably 30 or less. This is because when the number of terminal groups in the molecular chain increases, the toner has a large environmental dependency in the charging characteristics of the toner.

The polyester resin obtained here has a glass transition temperature of 50 to 75 ° C., preferably 55 to 65 ° C.
° C, and further, a number average molecular weight Mn of 1,500 to 50,000.
Preferably 2,000 to 20,000, weight average molecular weight Mw 6,000 to 100,000, preferably 10,000
It is preferably from 0 to 90,000.

In the toner for developing an electrostatic image of the present invention, a charge control agent can be used if necessary in order to further stabilize the chargeability. The charge control agent is a binder resin 100
0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight
It is preferred to use parts by weight.

Today, the charge control agents known in the art include:

To control the toner to be negatively charged,
For example, organic metal complexes and chelate compounds are effective. Examples thereof include a monoazo metal complex, an aromatic hydroxycarboxylic acid, a metal complex, and an aromatic dicarboxylic acid-based metal complex. Others include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters,
Phenol derivatives of bisphenol are mentioned.

Examples of the magnetic material contained in the magnetic toner of the present invention include iron oxides such as magnetite, maghemite, and ferrite, and iron oxides containing other metal oxides;
metals such as o and Ni, or these metals and A
1, Co, Cu, Pb, Mg, Ni, Sn, Zn, S
b, Be, Bi, Cd, Ca, Mn, Se, Ti, W,
Alloys with metals such as V, and mixtures thereof.

As a magnetic material, conventionally, triiron tetroxide (F
e_Three O_Four ), Iron sesquioxide (γ-Fe_Two O_Three ), Iron oxide
Lead (ZnFe_Two O_Four ), Yttrium iron oxide (Y_Three Fe
_Five O ₁₂), Cadmium iron oxide (CdFe_Two O_Four ), Oxidation
Iron gadolinium (Gd_Three Fe_Five -O₁₂), Iron oxide copper (C
uFe_Two O_Four ), Lead iron oxide (PbFe₁₂-O₁₉), Oxidation
Iron nickel (NiFe_Two O_Four ), Iron neodymium oxide (Nd
Fe_Two O_Three ), Barium iron oxide (BaFe)₁₂O₁₉),
Magnesium iron oxide (MgFe_Two O_Four ), Iron oxide manga
(MnFe_Two O_Four ), Iron oxide lanthanum (LaFeO)
_Three ), Iron powder (Fe), cobalt powder (Co), nickel powder
(Ni) and the like are known, but according to the present invention,
Magnetic materials used alone or in combination of two or more
I do. A particularly preferred magnetic material for the purposes of the present invention is triiron tetroxide.
Or a fine powder of γ-iron sesquioxide.

These ferromagnetic materials have an average particle size of 0.1 to 2
about 10 μm, the magnetic characteristics when a 10K Oersted is applied show a coercive force of 20 to 150 Oersted saturation magnetization of 50 to 200 e
mu / g (preferably 50 to 100 emu / g) and a residual magnetization of 2 to 20 emu / g are desirable.

With respect to 100 parts by weight of the binder resin, the magnetic material 1
It is preferable to use 0 to 200 parts by weight, preferably 20 to 150 parts by weight.

A coloring agent may be used in the toner of the present invention as needed. Colorants that can be used in the toner of the present invention include any suitable pigments or dyes.

For example, pigments include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, red bengala, phthalocyanine blue, and indanthrene blue. 0.1 to 100 parts by weight of resin
It is preferred to use up to 20 parts by weight, preferably 1 to 10 parts by weight of pigment. For the same purpose, a dye is further used. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, and 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight, per 100 parts by weight of the resin.
It is preferred to use parts by weight of the dye.

In the present invention, one or more release agents may be contained in the toner, if necessary.

The following are examples of the release agent used in the present invention. Aliphatic hydrocarbon-based waxes such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax, and paraffin wax; and aliphatic hydrocarbon-based waxes such as oxidized polyethylene wax, or block copolymers thereof; Examples include waxes mainly containing a fatty acid ester such as wax, sasol wax and montanic acid ester wax, and those obtained by partially or entirely deoxidizing fatty acid esters such as deoxidized carnauba wax.
Furthermore, saturated straight-chain fatty acids such as palmitic acid, stearic acid, and montanic acid, unsaturated fatty acids such as blandic acid, eleostearic acid, and vinaric acid, stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubavir alcohol, and seryl Alcohols, saturated alcohols such as merisyl alcohol, polyhydric alcohols such as sorbitol, fatty acid amides such as linoleic acid amide, oleic acid amide, lauric acid amide, methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebis Saturated fatty acid bisamides such as lauric acid amide, hexamethylene bisstearic acid amide, ethylene bisoleic acid amide, hexamethylene bis oleic acid amide, N, N'-dioleyl adipamide, N, N ' Unsaturated fatty acid amides such as dioleyl sebacamide, aromatic bisamides such as m-xylene bisstearic acid amide, N, N'-distearyl isophthalic acid amide, calcium stearate, calcium laurate, zinc stearate; Fatty acid metal salts such as magnesium stearate (commonly referred to as metal soaps), waxes obtained by grafting aliphatic hydrocarbon waxes with vinyl monomers such as styrene and acrylic acid, and behenin Examples include partial esterified products of fatty acids such as acid monoglycerides and polyhydric alcohols, and methyl ester compounds having a hydroxyl group obtained by hydrogenation of vegetable oils and the like.

The amount of the release agent used in the present invention is desirably 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of the binder resin.

These release agents are usually contained in the binder resin by dissolving the resin in a solvent, increasing the temperature of the resin solution and adding and mixing while stirring, or mixing at the time of kneading.

As the fluidizing agent used in the present invention, any material can be used as long as it can be added to the colorant-containing resin particles to increase the fluidity before and after the addition. . For example, fluorine-based resin powders such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder, fine powder silica such as wet-process silica, dry-process silica, and the like, silane coupling agent, titanium coupling agent, silicon oil, etc. And the like, surface-treated silica.

Preferred fluidizing agents are fine powders produced by vapor phase oxidation of silicon halide compounds.
It is what is called dry silica or fumed silica, and is manufactured by a conventionally known technique. For example, it utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.

SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl Also, in this production process, by using another metal halide such as aluminum chloride or titanium chloride together with the silicon halide, a composite fine powder of silica and another metal oxide can be obtained. It is also possible to obtain bodies, including them. The particle size is 0.0 as an average primary particle size.
It is desirable to be within the range of 01 to 2 μm, and it is particularly preferable to use silica fine powder within the range of 0.002 to 0.2 μm.

Commercially available silica fine powder produced by vapor phase oxidation of a silicon halide used in the present invention includes, for example, those commercially available under the following trade names.

AEROSIL (Nippon Aerosil) 130 200 300 380 TT600 MOX170 MOX80 COK84 Ca-O-SiL (CABOT Co.) M-5 MS-7 MS-75 HS-5 EH-5 Wacker HDK N20 V15 WAC -CHEMIE GMBH) N20E T30 T40 DC Fine Silica (Dow Corning Co.) Fransol (Fransil) Further, treated silica obtained by hydrophobizing silica fine powder generated by gas phase oxidation of the silicon halide. It is more preferable to use fine powder. It is particularly preferable that the treated silica fine powder is obtained by treating the silica fine powder such that the degree of hydrophobicity measured by a methanol titration test shows a value in the range of 30 to 80.

The method for imparting hydrophobicity is provided by chemically treating with an organic silicon compound or the like which reacts or physically adsorbs with the fine silica powder. As a preferred method, silica fine powder produced by vapor phase oxidation of a silicon halide is treated with an organosilicon compound.

Examples of such organosilicon compounds include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyl Dimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxy Silane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyl Disiloxane, 1,3-diphenyltetramethyldisiloxane and 2 to 12 per molecule
For example, dimethylpolysiloxane having a hydroxyl group bonded to Si and having one siloxane unit as a terminal unit may be used. These are used alone or as a mixture of two or more.

Good results are obtained when the fluidizing agent used in the present invention has a specific surface area of 30 m ² / g or more, preferably 50 m ² / g or more measured by nitrogen adsorption according to the BET method. Fluidizer 0.01 for 100 parts by weight of toner
To 8 parts by weight, preferably 0.1 to 4 parts by weight.

As the metal oxide powder used in the present invention, magnesium, zinc, aluminum, cobalt,
Examples include oxides such as iron, zirconium, manganese, chromium, and strontium, and composite metal oxides such as calcium titanate, magnesium titanate, strontium titanate, and barium titanate. Among them, zinc oxide, aluminum oxide, cobalt oxide, manganese dioxide, strontium titanate, and magnesium titanate are preferable because the effects of the present invention can be more exhibited. In particular, strontium titanate powder is preferable.

The metal oxide powder used in the present invention is produced by, for example, a sintering method, mechanically pulverized, then classified by air classification, and has a desired particle size and particle size distribution.

[0131] The metal oxide powder according to the present invention is used for toner 1
It is preferably used in an amount of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight.

To prepare the toner for developing an electrostatic image of the present invention, a binder resin, a magnetic substance, and if necessary, a colorant, a charge control agent or other additives are mixed with a mixer such as a Henschel mixer or a ball mill. Mix well, heat, knead and knead using a hot kneader such as a heating roll, kneader, extruder to make the resins compatible with each other, cool and solidify the melt-kneaded product, pulverize the solidified product, and pulverize. Can be obtained to obtain the toner of the present invention.

Further, the fluidizing agent, the metal oxide powder, the toner and the toner are sufficiently mixed by a mixer such as a Henschel mixer to obtain a developer for developing an electrostatic image of the present invention having an additive on the surface of toner particles. .

(1) Measurement of Particle Size Distribution The particle size distribution can be measured by various methods. In the present invention, the measurement was carried out using a Coulter counter multisizer.

That is, as a measuring apparatus, a Coulter counter Multisizer II (manufactured by Coulter) was used, and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a CX-1 personal computer (manufactured by Canon) were connected. Then, a 1% NaCl aqueous solution is prepared using a special grade or primary grade sodium chloride as an electrolytic solution. As a measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersing agent to 100 to 150 ml of the electrolytic aqueous solution, and the measurement sample is added to 2 to 100 ml.
Add ~ 20 mg. The electrolytic solution in which the sample is suspended is subjected to dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and a multi-sizer type II of the Coulter counter uses a 100 μm aperture when measuring the toner particle size as an aperture. 13μ when measuring the particle size of inorganic fine powder
Measure using an m aperture. The volume and the number of the toner and the metal oxide powder were measured, and the volume distribution and the number distribution were calculated. Then, the weight-based weight average diameter determined from the volume distribution according to the present invention is determined from the volume distribution.

(2) Measurement of Acid Value in Vinyl Resin The qualitative and quantitative determination of the functional group in the binder resin was carried out by infrared absorption spectrum, acid value measurement according to JIS K-0070, hydrolysis acid value measurement (total One example is a method using (acid value measurement).

For example, in the case of infrared absorption, 1780 cm ⁻¹
An absorption peak derived from the carbonyl of the anhydride appears in the vicinity, so the presence of the acid anhydride is confirmed.

In the present invention, the peak of the infrared absorption spectrum means a peak which is clearly recognized as a peak after 16 times of integration by FT-IR with a resolution of 4 cm ^-1 . F
As a model of T-IR, for example, FT-IR1600
(Manufactured by PerkinElmer).

Measurement of acid value according to JIS K-0070 (hereinafter referred to as J
The acid anhydride is about 50% of the theoretical value (the acid anhydride has an acid value as dicarboxylic acid).
Is measured.

On the other hand, in the measurement of the total acid value (A), a value substantially as a theoretical value is measured. Therefore, the total acid value (A) and J
Since the difference from the IS acid value is about 50% of the theoretical value and the acid anhydride is measured as a dibasic acid, the total acid value (B) derived from the acid anhydride per 1 g is obtained.

Total acid value (B) = [Total acid value (A) −JIS acid value] × 2 Further, for example, maleic acid monoester was used as an acid component, and a solution polymerization method and a suspension polymerization method were used. When adjusting the vinyl copolymer composition to be used as the coating resin,
The total acid value (B) is measured by measuring the JIS acid value and the total acid value (A) of the vinyl copolymer produced by the solution polymerization method, and the total acid value (B) and the solution polymerization method From the composition ratio of the vinyl monomer used in the above, the abundance (for example, mol%) of the acid anhydride generated in the polymerization step and the solvent removal step is calculated. Further, the vinyl copolymer prepared by the solution polymerization method is dissolved in a monomer such as styrene and butyl acrylate to prepare a monomer composition, and the prepared monomer composition is subjected to suspension polymerization. At that time, a part of the acid anhydride group is opened. From the JIS acid value, total acid value (A), monomer composition ratio of the vinyl copolymer composition obtained by the suspension polymerization method and the amount of the vinyl copolymer adjusted by the solution polymerization method, binding is performed. The amount of dicarboxylic acid groups, acid anhydride groups, and dicarboxylic acid monoester groups in the vinyl copolymer composition used as the resin can be calculated.

The total acid value (A) of the binder resin is obtained as follows. 2 g of sample resin is mixed with 30 ml of dioxane
And 10 ml of pyridine, 20 mg of dimethylaminopyridine and 3.5 ml of water are added thereto, and the mixture is refluxed for 4 hours while stirring. After cooling, 1 / 10N KOH
The acid value obtained by neutralization titration with a THF solution using phenolphthalein as an indicator is defined as the total acid value (A). Under the measurement conditions of the total acid value (A), the acid anhydride group is hydrolyzed to dicarboxylic acid, but the acrylate ester group, methacrylic ester group and dicarboxylic monoester group are not hydrolyzed.

The preparation of a 1 / 10N KOH / THF solution is performed as follows. 1.5 g of KOH is dissolved in about 3 ml of water, and 200 ml of THF and 30 ml of water are added thereto and stirred. If the solution has separated after standing, add a small amount of methanol,
If the solution is cloudy, add a small amount of water to make a uniform clear solution. The specified value of the KOH / THF solution is standardized with a 1 / 10N HCl standard solution.

The total acid value (A) in the binder resin is from 2 to 100
mgKOH / g, but the acid value according to JIS K-0070 of the vinyl copolymer containing the acid component in the binder resin is 1
Preferably it is less than 00. JIS K-0070
When the acid value is 100 or more, a carboxyl group,
The density of a functional group such as an acid anhydride group is high, so that it is difficult to obtain a good charge balance, and there is a tendency that a problem due to its dispersibility occurs even when diluted and used.

(3) Method of Measuring Acid Value of Polyester Resin The acid value is defined as the number of milligrams of potassium hydroxide required to neutralize the carboxyl group contained in 1 g of the resin. Therefore, the acid value indicates the number of terminal groups. The measuring method is as follows. Sample 2
10 to 10 g is weighed in a 200 to 300 ml Erlenmeyer flask, and a mixed solvent of methanol: toluene = 30: 70 (about 5: 5) is used.
Add 0 ml to dissolve the resin. If solubility is poor, a small amount of acetone may be added. Using a mixed indicator of 0.1% bromthymol blue and phenol red, titration is performed with a previously standardized N / 10 potassium hydroxide-alcohol solution, and the acid value is determined from the consumption of the alcoholic potassium solution by the following calculation.

Acid value = KOH (ml number) × N × 56.1 / sample weight (where N is a factor of N / 10 KOH) (4) Glass transition temperature Tg In the present invention, a differential thermal analyzer ( (DSC measurement device), DSC-7 (manufactured by PerkinElmer).

The measurement sample is 5 to 20 mg, preferably 10
Weigh the mg precisely.

This was put in an aluminum pan, and an empty aluminum pan was used as a reference.
The measurement is performed at a temperature rising rate of 10 ° C./min and at normal temperature and normal humidity between 0 ° C.

In this heating process, an endothermic peak of the main peak in the temperature range of 40 to 100 ° C. is obtained.

At this time, the intersection between the line of the midpoint of the baseline before and after the endothermic peak appears and the differential heat curve is defined as the glass transition temperature Tg in the present invention.

(5) Measurement of Molecular Weight In the present invention, the molecular weight of a chromatogram by GPC (gel permeation chromatography) is measured under the following conditions.

That is, the column was stabilized in a heat chamber at 40 ° C., and THF (tetrahydrofuran) was passed through the column at this temperature as a solvent at a flow rate of 1 ml per minute, and the sample concentration was 0.05 to 0.6 wt. % Of the THF sample solution of the resin adjusted to 50% to 200 μl is measured. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical
Co. Or Toyo Soda Kogyo Co., Ltd. with a molecular weight of 6
× 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 1
0 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10
⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and it is appropriate to use at least about 10 standard polystyrene samples. Also, the detector uses RI
A (refractive index) detector is used.

[0153] As the column, 10 ³ to 2 × 10
^In order to accurately measure the molecular weight region of ^6, a plurality of commercially available polystyrene gel columns are preferably combined.
μ-styragel 500, 10 manufactured by Aters
Combination of ³ , 10 ⁴ and 10 ⁵ and Showa Denko sho
dex KF-80M, KF-801, 803, 80
4, 805, KA-802, 803, 804,
805 combination or TSKgel manufactured by Toyo Soda
G1000H, G2000H, G2500H, G300
0H, G4000H, G5000H, G6000H, G
A combination of 7000H and GMH is preferred.

[0154]

The present invention will be described below with reference to production examples and examples.

[Production Example of Strontium Titanate] 600 g of strontium carbonate and 320 g of titanium oxide were wet-mixed in a ball mill for 8 hours and then filtered and dried. This mixture was molded at a pressure of 5 kg / cm ² and calcined at a temperature of 1100 ° C. for 8 hours.

Thereafter, the mixture was mechanically pulverized to a weight average diameter of 1.8 μm.
m, number average diameter 0.7 μm, particle size distribution [(m−D ₄ ) /
(M-D ₁ )] to obtain strontium titanate fine powder of 2.6. This is designated as strontium titanate A. The coarse powder and the fine powder were simultaneously removed by an elbow jet classifier utilizing the Coanda effect to obtain a weight average diameter of 1.4.
μm, number average diameter 1.0 μm, particle size distribution [(m-D ₄ )
/ (M-D ₁ )] 1.4 to obtain strontium titanate I. FIG. 4 shows the volume distribution and the number distribution of strontium titanate I.

Similarly, strontium titanates II to V having various particle size distributions were obtained.

[Production Example of Aluminum Oxide] Aluminum hydroxide was molded at a pressure of 1000 kg / cm ² ,
Sintering was performed at a temperature of 00 ° C. for 2 hours. Thereafter, by mechanical pulverization and classification by an elbow jet classifier, a weight average diameter of 4.0 μm, a number average diameter of 2.5 μm, and a particle size distribution [(m−
_{D 4) / (m-D} 1)] to give 1.6 aluminum oxide I of.

In the same manner, aluminum oxides II and III having different particle size distributions were obtained.

[Production example of zinc oxide]
It was molded at a pressure of Kg / cm ² and sintered at a temperature of 500 ° C. for 5 hours. Thereafter, zinc oxide I having a weight average diameter of 1.8 μm, a number average diameter of 1.2 μm, and a particle size distribution of [(m−D ₄ ) / (m−D ₁ )] 1.5 was obtained by mechanical pulverization and air classification. Was.

[Production Example 1 of Binder Resin] 76.0 parts by weight of styrene 13.0 parts by weight of butyl acrylate 11.0 parts by weight of monobutyl maleate 6.0 parts by weight of di-tert-butyl peroxide 6.0 parts by weight of the above material, It was added dropwise to 200 parts by weight of xylene heated to the reflux temperature over 4 hours. Furthermore, under xylene reflux (1
(38-144 ° C), and xylene was removed while heating to 200 ° C under reduced pressure. The resin thus obtained is referred to as resin A.

When the acid value of the resin A was measured, it was as follows.

[0163]

[Table 1] Resin A 30.0 parts by weight Styrene 45.0 parts by weight Butyl acrylate 20.0 parts by weight Monobutyl malate 5.0 parts by weight 0.5 parts by weight of divinylbenzene 1.5 parts by weight of benzoyl peroxide 1.5 parts by weight of polyvinyl alcohol Partially saponified 0.1
170 parts by weight of water in which 2 parts by weight were dissolved were added, and the mixture was vigorously stirred to obtain a suspension dispersion. The suspension dispersion was added to a reactor which was charged with 50 parts by weight of water and purged with nitrogen, and subjected to a suspension polymerization reaction at a reaction temperature of 80 ° C. for 8 hours. After completion of the reaction, the resin was washed with water, dehydrated and dried to obtain a resin.

In the obtained resin H, assuming that the total amount of the monobutyl maleate unit, maleic anhydride unit and maleic acid unit is 100 mol%, 73.3 mol% of monobutyl maleate unit and maleic anhydride Product unit 6.7 mol% and maleic acid unit 2
0 mol% was present.

The acid value of the binder resin B was determined as follows.

[0166]

[Table 2] The binder resin B has a glass transition point of 59 ° C., a gel content of 30%, a number average molecular weight Mn of 12,000, and a weight average molecular weight Mw.
It was 150,000. Using a Soxhlet extractor, 0.5 to 1.0 g of the binder resin was weighed, and the gel content was determined from the dry weight of the insoluble matter after extraction for 6 hours. The molecular weights Mw and Mn were measured using those excluding the gel component.

[Production Example 2 of Binder Resin] Bisphenol derivative represented by formula (A) 1320 parts by weight Fumaric acid 100 parts by weight Terephthalic acid 200 parts by weight Trimellitic acid 300 parts by weight The mixture was placed in a four-necked round-bottomed flask having a 3-liter container equipped with a stirrer, a glass nitrogen inlet tube, and a falling condenser. Next, this flask was placed in a mantle heater, nitrogen gas was introduced from a glass introduction tube to keep the inside of the reactor under an inert atmosphere,
The temperature was raised and dehydration condensation was performed at 220 to 250 ° C. The relationship between the viscosity and the molecular weight was grasped in advance, and when the viscosity reached a predetermined value, the resin was cooled and solidified to obtain a binder resin C.

The glass transition point Tg of the binder resin C is 60
° C, number average molecular weight Mn 7,800, weight average molecular weight M
w was 22,000.

Example 1 Resin B (binder resin) 100 parts by weight Magnetic iron oxide 80 parts by weight (average particle size 0.15 μm, Hc115 Oersted, σs80 emu / g, σr11 emu / g) Low molecular weight ethylene-propylene copolymer 4 Parts by weight monoazo complex (negative charge controlling agent) 2 parts by weight
Melt kneading was performed at 2 ° C. by a twin screw kneading extruder. After allowing the kneaded material to cool, coarsely pulverized with a cutter mill, pulverized using a fine pulverizer using a jet stream, and further classified using an air classifier, the weight average particle size (t-D ₄ ) 9 0.0 μm, number average diameter (t−D ₁ ) 7.0 μm, distribution [(t−D ₄ )
/ (T-D ₁ )] 1.3 fine black powder (negative triboelectrically charged magnetic toner) was obtained. FIG. 3 shows the volume distribution and the number distribution of the obtained magnetic toner.

To 100 parts by weight of the magnetic toner, 0.6 parts by weight of hydrophobic dry silica (BET 150 m ² / g) and 3.0 parts by weight of strontium titanate I were externally added by a Henschel mixer, and a developer (I) was added. ).

Using the obtained developer (a), a photosensitive drum of a Canon NP9330 laser copying machine is converted to an OPC photosensitive drum, and after charging with a negative corona, a latent image is formed with a laser and then reversal developed. Image evaluation was performed using a modified machine.

As a result, there was no fog on the white background, and the maximum image density was 1.48.
The density gradation was good. In addition, linearity that can be almost satisfied in the relationship between the development potential and the image density was obtained.
(FIG. 2) Further, a copy test of 30,000 sheets was performed. As a result, good results were also obtained in the fixing property.
The copy image was of good quality with little change from the initial image described above. Further, no scratch on the surface of the organic photoreceptor was observed, and as a result of measuring the thickness of the surface of the photoreceptor by using a quiescent current, the shaved amount of the surface layer of the photoreceptor was as small as 1.8 μm / 10,000 sheets. When the particle size of the developer on the developer carrier was measured, the particles had a weight average particle size of 9.6 μm and a number average particle size of 7.3 μm (initial weight average particle size of 9.0 μm and number average particle size of 6.8 μm). There is almost no change in diameter and distribution,
Good results were also obtained in selective developability.

Further, the carrier memory was also insignificant.

Further, a copy test was carried out at a low temperature and a low humidity (5 ° C., 10%) and at a high temperature and a high humidity (30 ° C., 80%), and good results were obtained as in the initial stage. A long-term (one week) test was conducted at high temperature and high humidity, and good results were obtained without any decrease in concentration.

Examples 2 to 7 A developer was prepared in the same manner as in Example 1 except that the material composition shown in Table 3 and the toner particle diameter were changed, and the same evaluation as in Example 1 was carried out. And the good results shown in FIG.

[0176]

[Table 3]

[0177]

[Table 4] Comparative Examples 1 to 8 A developer was prepared in the same manner as in Example 1 except that the material composition shown in Table 5 and the toner particle size were changed, and the same evaluation as in Example 1 was performed. Obtained. The metal oxide powder used was classified in the same manner as that used in the examples.

[0178]

[Table 5]

[0179]

[Table 6]

[0180]

The developer for developing an electrostatic image of the present invention has excellent development characteristics, and particularly has an excellent effect of suppressing selective development. Further, it is suitable as a developer for developing a latent image formed on an OPC photosensitive member using an organic photoconductive substance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a developing potential and a copy image density when a developer other than the present invention is used. In the figure, a solid line indicates a case where the maximum image density is 1.4 or more, and a broken line indicates This shows a case where the density gradation is improved.

FIG. 2 is a diagram showing a relationship between a development potential and a copy image density when a developer according to the present invention is used.

FIG. 3 is a particle size distribution diagram (100 μm aperture) of the insulating magnetic toner.

FIG. 4 is a particle size distribution diagram (13 μm aperture) of a metal oxide powder.

FIG. 5 is a particle size distribution diagram (13 μm) of a metal oxide powder before classification.
m aperture).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-68765 (JP, A) JP-A-2-46469 (JP, A) JP-A-62-148970 (JP, A) JP-A-1- 124867 (JP, A) JP-A 1-158459 (JP, A) JP-A 1-238673 (JP, A) JP-A 2-269366 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9 / 083,9 / 08

Claims (1)

(57) [Claims] A weight average particle size (tD ₄ ) of ₄ to 12 μm.
m, the number average particle diameter (t-D ₁ ) is ₁ to 10 μm, and the ratio of (t-D ₄ ) / (t-D ₁ ) is 1.01 to 2
An insulating magnetic toner, a fluidizing agent, and a weight average particle diameter (m-D ₄ ) of 0.6 to 5 μm, and a number average particle diameter (m-D ₁ ) of 0.5 to 4 μm. , (M
-D ₄ ) / (m-D ₁ ) ratio is 1.0 to 2.4;
The ratio of (m−D ₄ ) / (m−D ₁ ) is (t−D ₄ ) / (t
-D ₁ ), the metal oxide powder having a ratio equal to or greater than the ratio of -D ₁ ), wherein the compounding amount of the metal oxide powder is 2 times the compounding amount of the fluidizing agent.
A developer for developing an electrostatic image, wherein the developer is up to 8 times.