JPH0349107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a toner for developing electrostatic images.

2. Description of the Related Art Conventionally, electrostatic printing, electrophotography, and the like are well-known methods for forming a visible image by developing an electrical latent image with a developer. For example, as an electrophotographic method, U.S. Patent No. 2297691, Japanese Patent Publication No.
Various methods described in Japanese Patent Publication No. 23910, Japanese Patent Publication No. 43-24748, etc. are well known. In general, a photoconductive substance is used to form an electrical latent image on a photoreceptor that exhibits photoconductivity by various means, and then the latent image is developed with a developer to obtain a visible image, or as required. A toner powder image is transferred to paper or the like according to the requirements, and then fixed by heating, pressure, solvent vapor, etc. to obtain a visible image. In addition, in order to obtain a multicolor image, the original is exposed using a color separation filter, and the above process is repeated multiple times using color developers such as yellow, magenta, and cyan, and the toner images are superimposed to form a color image. It is something to do. Toner, which is one of the components of the developer, is conventionally made by dispersing a coloring agent (dye or pigment such as carbon black) in a binder resin such as polystyrene, which is then finely pulverized to about 1 to 30 microns. particles are used. Such toners are usually mixed with a carrier material such as glass beads, iron powder, or fur and used to develop the latent electrical image.

These developers are required to have various physical and chemical properties, and various improvements have been proposed heretofore. Nevertheless, many of the known developers have several deficiencies as described below. That is, the triboelectric properties of many developers are adversely affected by changes in environmental humidity.
In addition, in many developers, the toner particles and carrier particles collide with each other due to repeated development through continuous use, and the mutual deterioration of the toner, carrier particles, and photosensitive plate due to contact between these particles and the surface of the photosensitive plate. The density of the image changes or the background density increases,
Decrease the quality of copies. Furthermore, with many developers, when an attempt is made to increase the density of a copied image by increasing the amount of toner adhering to the surface of a photosensitive plate having a latent image, the background density usually increases, resulting in a so-called fog phenomenon.

Many of the known developers have one or more of the above-mentioned defects, despite numerous improvements being proposed, and there is still a continuing need for improved developers. .

The present invention has been made in view of the above-mentioned current situation. That is, the main object of the present invention is to provide a method for producing a toner that has excellent characteristics against repeated use due to continuous use.

Another object of the present invention is to provide a method for producing a toner with excellent triboelectric properties.

Still another object of the present invention is to provide a method for producing color toner particularly suitable for color electrophotography.

Specifically, the present invention provides a method for producing an electrostatic image developing toner produced by melt-mixing a binder resin and a plurality of constituent components, which has a better dispersion state than the dispersion state of the constituent components having the opposite polarity to the toner. So that
The step of dispersing a constituent component having the opposite polarity to the toner in the binder resin by mixing, and the step of dispersing the constituent component having the same polarity as the toner in the binder resin by kneading are carried out separately. The present invention relates to a method for producing a toner for developing an electrostatic image.

Furthermore, the present invention provides a method for producing a toner for developing an electrostatic image, which is produced by melt-mixing a binder resin and a plurality of constituent components, such that the dispersion state is better than that of the constituent components having the opposite polarity to the toner. The step of dispersing a constituent component having the opposite polarity to the toner in the binder resin using a solvent, and the step of dispersing the constituent component having the same polarity as the toner in the binder resin by kneading are separated. The present invention relates to a method for producing a toner for developing an electrostatic image, characterized by carrying out the following steps. Here, the polarity of the toner constituents (hereinafter also referred to as "toner constituents") can be determined by finely pulverizing each constituent, mixing well with carrier iron powder, and measuring the amount of triboelectric charge. . Conventionally, toner is composed of a binder resin, a colorant, and if necessary, a charge control agent, a fixing property improver, a powder property improver, etc., and these components do not necessarily all have the same polarity as the desired toner. Not necessarily. For example, carbon black, which is used as a coloring agent, has some types that tend to have positive (Posi) polarity and others that tend to have negative (Nega) polarity due to their surface active groups.
Carbon black, which tends to be positive due to its properties other than electrostatic properties, may have to be used as a negative toner. This situation is particularly noticeable in the case of color toner. It is essential for a color toner to exhibit a clearer hue, and the charge polarity of a colorant having a desired hue and the charge polarity of a color toner often do not match. Although the colorant has been described as an example, the same applies to other components, and generally, the components of toner are roughly divided into components with the same polarity as the toner and components with the opposite polarity. can do. Conventionally, these components were manufactured by pre-mixing all of them at the same time and dispersing each other in a process that uniformly dispersed each component, but in the present invention, components having the opposite polarity and components having the same polarity as the toner can be manufactured. This manufacturing method is characterized by having a step of separating and dispersing each in a binder resin.

The method of separating the constituent elements into two groups and dispersing them in the binder resin is as follows: (a) A dispersion mixture A is prepared in which the toner and the constituent elements of opposite polarity are dispersed in some of the binder resin; (b) A method in which a dispersion mixture B in which components of the same polarity as the toner are dispersed in a binder resin is prepared separately from A, and finally A and B are mixed. A dispersion mixture A is prepared in which components of opposite polarity are dispersed, and then this A
There are methods such as mixing and dispersing the remaining binder resin, toner, and components of the same polarity, but either method (a) or (b) can be preferably used in the present invention. Furthermore, in the present invention, the conditions for dispersing components of opposite polarity and the conditions for dispersing components of the same polarity do not necessarily have to be the same; rather, the dispersion state of the components of opposite polarity and the dispersion state of the components of the same polarity are different. It is better to stay in the same condition. Furthermore, it is more preferable that the dispersion state of the constituent elements of opposite polarity is better than the dispersion state of the constituent elements of the same polarity.

As the production equipment used to carry out the method of the present invention, any conventional dispersion equipment that has been generally used can be used, and the type thereof is not limited.

Furthermore, all conventionally known materials can be used for the toner.

The present invention will be explained in more detail with reference to Examples below. Comparative examples are also shown in order to more clearly understand the effects of the present invention. All parts shown in Examples and Comparative Examples are parts by weight.

Example 1 A negative polarity black toner consisting of the following components was prepared using the following method: epoxy resin (softening point: 105-110°C) 100 parts carbon black (black in color and high blackness, but positive polarity). ) 9 parts gold-containing black dye (screw polarity) 4 parts.

First, 40 parts of epoxy resin and 9 parts of positive polar carbon black were thoroughly premixed, and then kneaded in a pressure kneader while applying strong shear to obtain a carbon black dispersion mixture A. When this mixture A was observed under a microscope, it was observed that carbon black was uniformly dispersed throughout. Then epoxy resin
Mixture B was obtained by lightly kneading 60 parts of the mixture and 4 parts of the negative polar metal-containing dye in a two-roll mill without applying much force. When observing B, most of the dye was not dissolved but dispersed as particles, and the dispersion state was less uniform than that of mixture A, clearly indicating a different state between mixture A and mixture B. was. 49 parts of mixture A obtained as above and mixture
B64 parts were melt-mixed again in a two-roll mill,
After cooling, it was coarsely pulverized using a hammer mill, and then finely pulverized using an air jet type pulverizer.
Further, the obtained fine powder was classified to select 5 to 20 microns to obtain a negative polarity (chargeable) toner. this toner
A negative polarity black developer was prepared by mixing 12 parts of the carrier iron powder with 88 parts of carrier iron powder.

Using this developer, the electronic copying machine (NP-5000)
(manufactured by Canon), copies with good image quality were obtained without any major deterioration phenomenon from the initial stage up to at least 20,000 copies.

Comparison row 1 The same components as in Example-1 were used, all the elements were kneaded and dispersed at once as in the conventional method, and the rest was carried out in the same manner as in Example-1. In both cases, up to 10,000 sheets, an increase in the density of solid areas and the occurrence of fogging were observed. The drawings show changes in the amount of triboelectric charge caused by continuous use of the developer produced by the production method of Example-1 and the developer produced by the production method of Comparative Example-1. It is clearly seen that the developer according to Example 1 has excellent triboelectric properties.

Example 2 A positive polar magenta toner consisting of the following components was manufactured by the following method.

Styrene-acrylic acid ester copolymer 100 parts Styrene-dialkylaminomethyl acrylate copolymer (positive polarity) 5 parts Rhodamine-based red dye (positive polarity) 2 parts Anthraquinone-based red dye (negative polarity)
1.5 parts Styrene-acrylic acid ester copolymer 30
and 1.5 parts of a negative polar anthraquinone dye are dissolved in methyl ethyl ketone and mixed vigorously using a stirrer such as a homomixer. The solvent was sufficiently evaporated from the resulting solution to obtain a red solid mixture C.
When this mixture C was observed under a microscope, the entire resin was colored extremely uniformly, and almost no particulate dye was observed. 31.5 parts of this mixture C, 2 parts of positive polar rhodamine dye, and 2 parts of positive polar styrene dye.
Dialkylaminomethyl acrylate copolymer 5
2 parts and 70 parts of styrene-acrylic acid ester were added in substantially the same manner as in obtaining mixture B of Example-1.
The mixture was heated and mixed on a roll mill. When this mixture was observed under a microscope, it was found that the negative polar dye showed a uniformly dissolved state, whereas the positive polar dye showed a clearly less uniformly dispersed state. After cooling, this mixture was made into a toner in the same manner as in Example 1 to obtain a positive polar magenta toner. When this toner was used to develop a negative electrostatic latent image on zinc oxide photosensitive paper, an extremely clear magenta image was obtained. Also, 2000 copies were made continuously using this device, and good image quality was maintained.

Comparative Example 2 The same components as in Example 2 were used, all the elements were melted and kneaded at once as in the conventional manufacturing method, and the rest was carried out in the same manner as in Example 2. In both cases, deterioration phenomenon was observed within 500 sheets. When the toner at this time was observed under a microscope, both the negative polar dye and the positive polar dye showed the same degree of dispersion.

[Brief explanation of drawings]

The drawings are diagrams showing changes in the amount of triboelectric charge when the toners of Example 1 and Comparative Example 1 of the present invention are used continuously.

Claims (1)

[Claims] 1. In a method for producing a toner for developing an electrostatic image, which is produced by melt-mixing a binder resin and a plurality of constituent components, the dispersion state of the constituent components having opposite polarity to that of the toner is different from that of the toner. A step of dispersing the constituent components having the opposite polarity to the toner in a binder resin by kneading so that the dispersion state is better than that of the constituent components having the same polarity, and binding the constituent components having the same polarity as the toner. A method for producing a toner for developing an electrostatic image, characterized in that a step of dispersing the toner by kneading into a resin binder is carried out separately. 2. In a method for producing an electrostatic image developing toner produced by melt-mixing a binder resin and a plurality of constituent components, the dispersion state of the constituent component having the opposite polarity to that of the toner is the same as that of the toner. A step of dispersing a component having a polarity opposite to that of the toner in a binder resin using a solvent, and a step of dispersing a component having the same polarity as that of the toner in a binder resin so that the dispersion state is better than that of the toner. A method for producing a toner for developing an electrostatic image, characterized in that the step of dispersing by kneading and the step of dispersing by kneading are carried out separately.