JPH09325521A - Electrostatic image developing toner and electrostatic image developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To not only give a good picture quality over a long period of time but also to form a good developed picture even at a change of an environment from low temp. low humidity to high temp. high humidity by treating a pigment with a modified silicone oil having one org. group out of an amino group and an epoxy group. SOLUTION: In the electrostatic image developing toner consisting of particles having essentially a thermoplastic resin based binder and pigment particles, the pigment is treated with the modified silicone oil having either one org. group of the amino group or the epoxy group. When the pigment is treated with such the silicone oil, the pigment maintains a good fluidity over a long period of time, and a change of a charge property of the toner is suppressed, and a high picture quality and a high transfer efficienc are easily secured. Such the toner, for example in a laser beam printer, is supplied on a surface of a developing roller 1 with a rotary agitator 4 and a toner feed roller 5 housed and mounted in an inside of a toner hopper 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner and a developing method using the electrostatic image developing toner. More specifically, a clear image can be formed, and the sharpness of the image can be maintained for a long period of time. The present invention relates to an electrostatic image developing toner and an electrostatic image developing method that are maintained or held for a long time.

[0002]

2. Description of the Related Art Generally, an electrostatic charge image formed on a photoconductor surface in a dark place is developed (visible image) by adhering colored powder to the electrostatic charge image. This colored powder is called an electrostatic image developing toner (hereinafter abbreviated as toner), and usually, it is prepared by dispersing a particulate pigment (or dye) in a thermoplastic resin (binder component) and then adjusting the particle size to a desired one. It was prepared by crushing.

By the way, in recent years, there has been a strong demand for improvement of toner characteristics in response to higher definition (or higher definition) of copied images and improvement of copying speed. Here, since the state in which the pigment is dispersed in the resin binder affects the image characteristics of the toner, it is important to properly control these characteristics. That is, when the primary particles of the pigment are aggregated and dispersed / mixed in the resin binder, the developed toner prepared by finely pulverizing (pulverizing) the pigment tends to lack coloring power and transparency. Also, the surface of the toner particles is coated with the primary particles of the pigment generated by crushing the aggregate of the pigment. As a result, the moisture resistance of the toner is reduced, and when the image is developed in a high humidity atmosphere, the toner adheres to a portion other than the electrostatic latent image, causing so-called fog,
There is a problem that a good developed image cannot be obtained.

In this sense, it can be said that it is preferable that the pigment particles are dispersed in the binder resin in such a manner that the binder resin is adsorbed on the surface of the primary particles of the pigment and is uniformly coated as a whole.

[0005]

However, the binder resin (resin binder) that is usually used has a functional group as an unreacted residue in the molecule, and this functional group is a functional group to the surface of the pigment particle. Since it is spent on adsorption, the chargeability originally possessed by the binder resin changes significantly. Such influence / effect also appears in the charge control agent added to control the charge of the toner. That is, the functional group of the pigment particles interacts with the functional group of the charge control agent to impair the charge control function originally possessed by the charge control agent, resulting in stable development of high quality images. I can't. In other words, while improving the dispersibility of the pigment particles, an electrostatic image that maintains (maintains) the required charging characteristics even when the environment such as temperature and humidity changes and always gives a clear image without fog. The development of developing toner is awaited.

The present invention has been made in view of the above circumstances, and not only provides a good developed image quality, but always produces a good developed image even when the environment changes from low temperature / low humidity to high temperature / high humidity. An object is to provide an electrostatic image developing toner that can be formed and a developing method.

[0007]

According to a first aspect of the present invention, there is provided an electrostatic image developing toner comprising a thermoplastic resin binder and particles containing pigment particles as main components, wherein the pigment is at least an amino group or an epoxy group. An electrostatic image developing toner characterized by being treated with a modified silicone oil having an organic group of any one of the above.

According to a second aspect of the present invention, there is provided an electrostatic image developing toner comprising a thermoplastic resin binder and particles containing pigment particles as main components, wherein the pigment is an organic group having at least one of an amino group and an epoxy group. An electrostatic image developing toner characterized by being treated with a mixture of a modified silicone oil having a group and a rosin modified resin having an organic group of either an amino group or an epoxy group.

The invention of claim 3 is characterized in that, in the electrostatic image developing toner of claim 1 or 2, the specific surface area of the pigment particles is 10 to 100 m ² / g or more.

The invention of claim 4 is the electrostatic image developing toner according to any one of claims 1 to 3, wherein the modified silicone oil has a molecular weight in the range of 500 to 500000.

According to a fifth aspect of the invention, when the electrostatic image developing toner is supplied to the latent image surface formed on the latent image forming member forming the latent image to develop the electrostatic latent image, the toner is used as the toner. Uses an electrostatic image developing toner composed of particles which are mainly composed of a thermoplastic resin binder and pigment particles, and in which the pigment is treated with a modified silicone oil having at least either an amino group or an epoxy group as an organic group. The electrostatic image developing method is characterized in that

The present invention was made based on the following findings. That is, as a result of intensive studies by the present inventors, when the surface of a pigment particle is surface-treated with a silicone oil containing at least one kind of organic group in the molecule, an organic group is present. It has been found that while maintaining good dispersion fluidity, change in chargeability of the toner is suppressed, and high quality images and high transfer efficiency can be easily secured. And based on such knowledge, not only does it give good development image quality and keeps good image quality (image quality does not change), but also when the environment changes from low temperature / low humidity to high temperature / high humidity. The present invention provides an electrostatic image developing toner capable of forming a good developed image and a developing toner capable of maintaining a vivid image color tone for a long time.

In the toner of the present invention, examples of the thermoplastic resin serving as the binder component include polyethylene resin, polyester resin, polystyrene resin, epoxy resin, styrene / acryl copolymer resin, polycarbonate resin, and the like. They may be used alone or in combination of two or more.

In the toner of the present invention, examples of the pigment serving as a coloring component include carbon black, phthalocyanine blue, azo lake pigment and quinacridone pigment. Here, the thermoplastic resin and the pigment are used as powder (particles) of several μm to several tens of μm through a process of mixing, kneading, pulverizing and classifying including a toner preparation process.

In the preparation of the toner, a dispersing resin for improving the dispersion of the pigment in the thermoplastic resin (binder), a charge control agent for imparting a desired charge to the toner, and a good fluidity. The fluidizing agent and the like may be added.

In the present invention, the silicone oil used for treating and modifying the surface of the pigment particles is, for example, a modified silicone in which an alkylamino group or an alkylepoxy group is bonded to the terminal or side chain of dimethylpolysiloxane or methylphenylpolysiloxane. It is an organopolysiloxane having a linear molecular structure called oil. Here, the alkylamino group and alkylepoxy group preferably have an amino group equivalent and an epoxy group equivalent of about 300 to 50,000 g / mol.

The modified silicone oil generally has a molecular weight of about 500 to 500,000, more preferably about 5,000 to 100,000. That is,
In the case of modified silicone oil with a small molecular weight, no remarkable effect is observed in terms of imparting water repellency to the toner surface and improvement of development characteristics, and in the case of modified silicone oil with a too large molecular weight, the pigment particles are uniformly dispersed. This is because it is difficult to cover the surface and it is difficult to obtain the desired effect.

As this type of modified silicone oil,
Those represented by the following general formula are exemplified as preferable ones.

[0019]

Embedded image

Embedded image

Embedded image

Embedded image In the present invention, the pigment particles are treated with the modified silicone oil by adding, for example, 0.5 to 10 parts by weight of the modified silicone oil to 100 parts by weight of the pigment particles, and then adding a high speed stirrer such as a kneader or a mixer and pulverizing. It is done by mixing with a machine. In addition, in this mixing, a mixer using a medium represented by a ball mill or a sand grinder may be used, or modified silicone oil may be solubilized with a solvent, and pigment particles may be added to this solution to form a sand grinder. It is also possible to adopt a method of drying and crushing a mixture of the above.

After the above both are mixed, the surface-treated pigment particles obtained by this mixing are kept in an oven at 80 to 150 ° C. for 1 hour or more to make the surface attachment of the modified silicone oil almost complete. . Thus, on the surface of the obtained treated pigment particles, silicone oil is almost uniformly adsorbed with a functional group such as an epoxy group on the pigment particle surface side, and it becomes a pigment particle (powder) having a substantially hydrophobic surface. ing. Here, when the pigment particles have a hydroxyl group or a carbosyl group, the amino-modified silicone oil is adsorbed and attached in an acid-base manner.

The process of treating the pigment particles with the modified silicone oil is particularly effective when the epoxy group-containing silicone oil and the amino group-containing silicone oil are used in combination. That is, the modified silicone oil is
This is because they are basically adsorbed on the surface of the pigment particles, and these molecules are entangled and firmly adhered.

In the treatment of the pigment particles with the modified silicone oil, a part (within 10 to 70% by weight) of the modified silicone oil may be replaced (substituted) with a rosin-modified resin. Here, examples of the rosin-modified resin (rosin-modified compound) include the following esterified products. For example, the carbosyl group in the resin acid of abietic acid, neoabietic acid, dehydroabietic acid, levopimaric acid, parastophosphoric acid, pimaric acid, isopimaric acid, and sandaracopimaric acid nad was esterified with an alcohol having an epoxy group or an amino group. Examples thereof include those obtained by introducing an epoxy group or an amino group into the alcohol portion after esterification with alcohol.

The surface treatment when the rosin-modified resin is used in combination may be performed in the same manner as the treatment with the modified silicone oil. In this case, the siloxane chain of the modified silicone oil and the polycyclic portion of the rosin-modified resin face toward the opposite side of the pigment surface to give a lipophilic surface.

In the developing method of the present invention, the developing device used for carrying out the developing method may be any one as long as it is used in the developing method using a one-component non-magnetic toner.

In the inventions of claims 1 and 2, the surface and the surface of the pigment particles are treated with a silicone oil containing an organic group of at least one of an amino group and an epoxy group in the molecule. Due to the pigment particles adopting this form and configuration, excellent moisture resistance is imparted,
The toner has a stable positive charge, and its fluidity is remarkably improved to allow uniform toner supply to the developing section.

Further, the image quality does not fluctuate due to environmental changes, and it is always possible to develop a clear image without fog. Further, the workability of kneading with the binder resin is greatly improved and improved with the treatment of the pigment particles, and the transparency of the image after heat fixing can be secured due to the good dispersibility. In particular, when the pigment particles treated together with the rosin-modified resin are used, good dispersibility in various binder resins is exhibited.

In the inventions of claims 3 and 4, by selecting the specific surface area of the pigment particles within a certain range, the molecular weight of the modified silicone oil that coats and modifies the surface of the pigment particles is more appropriate. By setting the range to, the action and effect are further promoted.

According to the invention of claim 5, the electrostatic image is developed into a visible image (development) by the electrostatic image developing toner exhibiting the above-mentioned effects.
Therefore, it is possible to stably form a high-quality image, and further, an image that retains high image quality for a long period of time.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples.

Example 1 100 parts by weight of phthalocyanine blue having a dry primary average particle diameter of 0.03 μm and a specific surface area of 40 m ² / g was added to a side chain amino-modified silicone oil (amino group equivalent 1700, molecular weight about 40,000) 1
A mixture was prepared by adding 0 part by weight. This mixture was mixed with a kneader for about 1 hour and then held in an oven at 100 ° C for 2 hours to obtain surface-modified pigment particles.

After 3 parts by weight of the surface-modified pigment particles were added and kneaded with 92 parts by weight of a polyester resin, 3 parts by weight of a positive charge control agent and 2 parts by weight of a polyethylene wax, the kneaded product was pulverized. To prepare a toner having an average particle size of 6 μm. 100 parts by weight of these toner particles have a primary average particle size of
1 part by weight of 10 μm positively charged silica powder was added and mixed with a mixer to obtain a developing toner.

The prepared developing toner was filled in a one-component developing machine, a positively charged electrostatic image was developed by a laser beam printer, and transferred / fixed on plain paper. When the background stain (fogging level) of the obtained image was measured with a color difference meter, it was 1.0% or less, and a clear image with very little fog was obtained. Further, even after continuously developing 20000 sheets of electrostatic images at room temperature and humidity, no deterioration was observed and a clear image was formed. Furthermore, under the conditions of 35 ° C and 80% relative humidity, even after 20000 sheets of continuous electrostatic image development, no deterioration was observed and a clear image without fogging was formed and heat fixing was performed. The later image was also excellent in transparency.

FIG. 1 is a cross-sectional view of an essential part showing the structure of a laser beam printer used in the developing method of this embodiment. In FIG. 1, reference numeral 1 denotes a toner carrier (developing roller), which rotates counterclockwise in the drawing at a peripheral speed Vt (mm / sec). The surface conductor layer of the developing roller 1 and the metal shaft are in a conductive state, and the developing bias power source 2 is connected to the metal shaft.

On the other hand, toner is supplied to the surface of the developing roller 1 by a rotary stirring device (rotary stirring bar) 4 and a toner supply member (toner supply roller) 5 which are housed and mounted in the toner hopper 3. , Toner layer forming member 6
The toner thin layer 7 having a uniform thickness is formed by the regulating action of. Thus, the toner layer 7 formed on the surface of the developing roller 1 comes into contact with a latent image forming member (for example, a photosensitive drum using a positive charging type organic photoconductor) 8 to develop the latent image on the surface of the photosensitive drum 8. Be seen. Further, in FIG. 1, 9 is a transfer device, 10 is a cleaning means, 11 is a charging means (charger),
Reference numerals 12 denote exposure means (laser beams) for selectively forming a required latent image on the surface of the photosensitive drum 8. Further, as the condition of the developing process, the photoconductor 8 is charged to +55 OV by corona charging. This electrification can be selected from corona electrification by corona wire (better electrification is possible when a grid is attached), roller electrification, brush electrification, etc. Here, corona electrification was used. The charging potential varies depending on the photoconductor 8 and the charger 11 used, but in the case of positive charging, the optimum potential may be selected within the range of + 400V to + 700V.

In the above example, instead of using the pigment particles treated with amino-modified silicone oil, epoxy-modified silicone oil (epoxy group equivalent 1500, molecular weight approx.
10000), but with the same development toner,
Even when the electrostatic image was developed, the same actions and effects as above were observed.

Example 2 100 parts by weight of carbon black having a primary average particle diameter of 0.02 μm and a specific surface area of 50 m ² / g, 5 parts by weight of an epoxy-modified silicone oil (epoxy group equivalent 1500, molecular weight about 10000), and an epoxy group were contained. A mixture was prepared by adding 5 parts by weight of a rosin-modified resin. This mixture was mixed with a kneader for about 1 hour and then held in an oven at 100 ° C for 2 hours to obtain surface-modified pigment particles.

After 3 parts by weight of the surface-modified pigment particles were added and kneaded with 87 parts by weight of a polyester resin, 3 parts by weight of a positive charge control agent and 2 parts by weight of a polyethylene wax, the kneaded product was pulverized. To prepare a toner having an average particle size of 10 μm. 100 parts by weight of these toner particles have a primary average particle size of
1 part by weight of 10 μm positively charged silica powder was added and mixed with a mixer to obtain a developing toner.

The prepared developing toner was filled in a one-component developing machine, a positively charged electrostatic image was developed by a laser beam printer, transferred and fixed on plain paper, and then a background stain ( When the fog level) was measured, a clear developed image with very little fog was obtained at 1.0% or less. Further, the developing characteristics were very stable, and the image after continuous copying of 20000 sheets while replenishing the toner was also good and comparable to the initial image.

The above-mentioned developing toner also exhibits stable developing characteristics even in an environment of high humidity, at a temperature of 35 ° C. and a relative humidity.
The developed image under the 80% environment was comparable to the developed image under normal temperature and normal humidity. Further, the transparency of the heat-fixed image was also good.

In this example, a surface-modified pigment powder was used in which a surface coating layer was prepared by substituting a part of epoxy-modified silicone oil (epoxy equivalent 1500, molecular weight about 10,000) with a general rosin-modified resin. Also in the case of the developed toner, the same action and effect as above were recognized.

In the above example, instead of using pigment particles treated with epoxy-modified silicone oil, amino-modified silicone oil (amino group equivalent 500, molecular weight about 30) was used.
The same action and effect as described above were observed when the electrostatic image was developed with the developing toner prepared in the same manner except that (00) was used.

Example 3 100 parts by weight of azo yellow having a primary average particle diameter of 0.02 μm and a specific surface area of 70 m ² / g, 5 parts by weight of epoxy-modified silicone oil (epoxy group equivalent 1500, molecular weight about 10000), and epoxy group A suspension of 5 parts by weight of the rosin-modified resin contained in 100 parts by weight of methyl ethyl ketone was added to prepare a suspension. After mixing this suspension with a kneader for about 1 hour, after separating and volatilizing methyl ethyl ketone from the suspension,
It was kept in an oven at 100 ° C for 2 hours to obtain surface-modified pigment particles.

3 parts by weight of the surface-modified pigment particles, 87 parts by weight of styrene-butyl acrylate copolymer resin, 3 parts by weight of positive charge control agent, polyethylene wax 2
After adding parts by weight and kneading, the kneaded product was finely pulverized to prepare a toner having an average particle size of 6 μm. This toner particle 100
To 1 part by weight of positively charged silica powder having a primary average particle size of 10 μm was added to 1 part by weight and mixed by a mixer to obtain a developing toner.

The prepared developing toner is filled in a one-component developing machine, a positively charged electrostatic image is developed by a laser beam printer, transferred and fixed on plain paper, and then a background stain ( When the fog level) was measured, a clear developed image with very little fog was obtained at 1.0% or less. Further, the developing characteristics were very stable, and the image after continuous copying of 20000 sheets while replenishing the toner was also good and comparable to the initial image.

The above-mentioned developing toner also exhibits stable developing characteristics even in an environment of high humidity, at a temperature of 35 ° C. and a relative humidity.
The developed image under the 80% environment was comparable to the developed image under normal temperature and normal humidity.

Example 4 100 parts by weight of a quinacridone pigment having a primary average particle diameter of 0.03 μm and a specific surface area of 40 m ² / g, 5 parts by weight of amino-modified silicone oil (amino equivalent 1500, molecular weight about 10000), and epoxy group-containing rosin A suspension was prepared by adding a solution prepared by dissolving 5 parts by weight of the modified resin in 100 parts by weight of methyl ethyl ketone. After mixing this suspension with a kneader for about 1 hour, separate and volatilize methyl ethyl ketone from the suspension, then
It was kept in an oven at 00 ° C for 2 hours to obtain surface-modified pigment particles.

3 parts by weight of the surface-modified pigment particles, 87 parts by weight of styrene / butyl acrylate copolymer resin, 3 parts by weight of a positive charge control agent, polyethylene wax 2
After adding parts by weight and kneading, the kneaded product was finely pulverized to prepare a toner having an average particle size of 6 μm. This toner particle 100
To 1 part by weight of positively charged silica powder having a primary average particle size of 10 μm was added to 1 part by weight and mixed by a mixer to obtain a developing toner.

The above-prepared developing toner is filled in a one-component developing machine, a positively charged electrostatic image is developed by a laser beam printer, transferred to and fixed on plain paper, and then a background stain ( When the fog level) was measured, a clear developed image with very little fog was obtained at 1.0% or less. Further, the developing characteristics were very stable, and the image after continuous copying of 20000 sheets while replenishing the toner was also good and comparable to the initial image.

The above-mentioned developing toner also exhibits stable developing characteristics even in a high humidity environment, at a temperature of 35 ° C. and a relative humidity.
The developed image under the 80% environment was comparable to the developed image under normal temperature and normal humidity.

Comparative Examples 1 to 3 Three kinds of developing toners were prepared under the same conditions as in Examples 1 to 3 except that pigment particles (powder) not surface-treated with modified silicone were used. . An electrostatic image was developed using each of these developing toners in the same manner as in Examples 1 to 3, and transferred / fixed onto plain paper. When the background stain level of each of the obtained images was measured by a color difference meter, all were high at 3 to 5%, and the levels required improvement.

Further, these toners were filled in a one-component developing machine, and a positively charged electrostatic image was developed by a laser beam printer in an environment of temperature 35 ° C. and relative humidity 80%, and transferred / fixed onto plain paper. Repeatedly, about 2000 sheets were repeated for the polyester resin-based toner (Comparative Examples 1 and 2), and about 4000 sheets were repeated for the styrene-butyl acrylate copolymer resin base toner (Comparative Example 3). Repeatedly, the toner adheres to the surface of the photoconductor as a film,
The fog level was significantly worse.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the base toner particles to which the external additive is attached on the surface may be based on toner particles containing a thermoplastic resin other than styrene-acrylic resin base toner particles and polyester resin base toner particles as a binder component.

[0053]

As can be seen from the above examples, the electrostatic image developing toner according to the present invention has remarkably improved handling properties and can be developed into a clear developed image with less fog. In addition, the electrostatic image developing toner has excellent durability without deteriorating the developed image even when repeatedly used for development.

Further, in the electrostatic image developing toner, pigment particles (fine pigment powder) are not attached and exposed on the surface of the toner (form imparting water repellency), and the toner is stable and clear even in a high humidity environment. It is possible to form a developed image.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main configuration of a laser printer used in an example.

[Explanation of symbols]

 1 ... Developing roller 3 ... Toner hopper 5 ... Toner supply member 6 ... Toner layer thickness regulating member 8 ... Electrostatic image forming member (photosensitive drum) 9 ... Transfer device 11 ... Charging means 12 ... Exposure means

Claims (5)

[Claims] 1. An electrostatic image developing toner comprising particles mainly composed of a thermoplastic resin binder and pigment particles, wherein the pigment has a modified silicone having at least one of an organic group of an amino group and an epoxy group. An electrostatic image developing toner characterized by being treated with oil. 2. An electrostatic image developing toner comprising particles containing a thermoplastic resin binder and pigment particles as main components, wherein the pigment has a modified silicone having at least one of an organic group of an amino group and an epoxy group. An electrostatic image developing toner, which is treated with a mixture of an oil and a rosin-modified resin having an organic group of either an amino group or an epoxy group. 3. The electrostatic image developing toner according to claim 1, wherein the specific surface area of the pigment particles is 10 to 100 m ² / g or more. 4. The modified silicone oil has a molecular weight of 500 to
4. The electrostatic image developing toner according to claim 1, which is in a range of 500,000. 5. When supplying an electrostatic image developing toner to the latent image surface formed on a latent image forming member which forms a latent image to develop the electrostatic latent image, a thermoplastic resin-based toner is used as the toner. An electrostatic image developing toner comprising particles containing a binder and pigment particles as main components, and the pigment being treated with a modified silicone oil having at least one of an organic group of an amino group and an epoxy group. Electrostatic image development method.