JPH0238947B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrostatic charge developing toner. More specifically, carbon black (hereinafter referred to as
It's called CB. ) is uniformly dispersed, and can therefore be used as toner for a wide range of electrophotographic developing devices, such as laser printers, liquid crystal printers, etc., to form clear images. Regarding developing toner.

(Prior Art) In electrophotography, an electrical latent image is formed on a photoreceptor made of a photoconductor material such as selenium, zinc oxide, or cadmium sulfide, and this is developed with a powder developer. It is transferred to paper or the like and fixed.

Conventionally, toners used for developing electrostatic images are:
Generally, colorants and other additives (charge control agents, anti-offset agents, lubricants, etc.) are melt-mixed and dispersed in a thermoplastic resin, and then the solidified material is finely pulverized and classified to produce colored fine particles of the desired particle size. It has been manufactured as.

However, the method of manufacturing toner by pulverization described above has various drawbacks. For example, in order to obtain toner with the optimum particle size range to form clear images with minimal fog, the classification process is an essential requirement, but the pulverization process completely removes fine and coarse particles produced as by-products. It is difficult to do so, and there are also problems in terms of yield. Furthermore, it is extremely difficult to uniformly disperse colorants and the like in the resin, especially during the kneading process. For this reason, the triboelectricity of the toner is not uniform, which poses a problem in forming clear images with little fog.

Furthermore, in order to overcome the drawbacks of toner manufacturing methods using pulverization methods, various toner manufacturing methods using emulsion polymerization methods or suspension polymerization methods have been proposed.
(Special Publication No. 36-10231, Japanese Patent Publication No. 10799, Japanese Patent Publication No. 43-10799, Japanese Patent Publication No. 47-518305, Japanese Patent Publication No. 51-14895, etc.) These methods involve adding a colorant substance such as CB to a polymerizable monomer,
In this method, a toner containing a colorant substance is synthesized all at once by adding other additives and carrying out emulsification or suspension polymerization. With this method it is possible to considerably improve the drawbacks of conventional grinding methods. However, the colorant added, especially CB, is not uniformly dispersed,
As a result, variations in the electric resistance and triboelectric charge of toner particles increase, and technical problems remain in obtaining a toner that can form excellent images.

Regarding this problem, as a method for successfully dispersing CB in polymerizable monomers, there is a method of treating CB with a coupling agent such as triethoxysilane (JP-A No. 53-17736 or JP-A No. 53-17737). , or a method using grafted CB (Japanese Unexamined Patent Publication No. 116044/1983), various methods have been studied. However, the CB obtained by these methods is a secondary agglomerated state of CB before being processed or grafted.
Because the resin retains its shape, the dispersibility in the resin does not improve as much as expected, and the cost only increases.

(Problems to be solved by the invention) The present inventors have solved the problems in the prior art, namely
In view of the current situation where CB is not uniformly dispersed in the resin, resulting in images that lack sharpness and problems such as fogging, we have conducted extensive research to solve this problem, and as a result, we have developed a specific structure. The present inventors have discovered that an electrostatic image developing toner containing a CB graft polymer has CB uniformly dispersed in a resin, thereby achieving the above object, and have completed the present invention.

(Means for solving the problems) The present invention provides carbon black with an aziridine group,
A polymer having in its molecule one or more reactive groups selected from oxazoline groups, N-hydroxyalkylamide groups, epoxy groups, and isocyanate groups (hereinafter referred to as polymer (A)) at 50°C. ~350
This invention relates to a toner for developing electrostatic images containing a carbon black graft polymer obtained by mixing and stirring under conditions of .degree. C. and reacting.

In the present invention, in order to obtain a CB graft polymer, functional groups (-OH, -COOH,
C=O, etc.). That is, the polymer (A) is as described above and can easily react with the functional group present on the surface of CB, but preferably the reactive group is an aziridine group, an oxazoline group, or an N-hydroxyalkylamide group. It is a polymer having , an epoxy group, and an isocyanate group. As such a polymer (A),
Examples include vinyl resins, polyester resins, epoxy resins, and amino resins having one or more of the above-mentioned reactive groups in the molecule.

The method for producing such a polymer (A) is not particularly limited, and includes, for example, a method of polymerizing a monomer component that essentially contains a polymerizable monomer having the aforementioned reactive group; It can be easily produced by a method of reacting a compound having the above-mentioned reactive group with a polymer having a functional group other than the above, such as a carboxyl group or a hydroxyl group.

The CB graft polymer in the present invention is obtained by reacting a polymer (A) having a reactive group with CB, and the polymer (A) is graft-bonded to CB with extremely high efficiency. The reaction of CB and polymer (A) is carried out by mixing and stirring under conditions of 50°C to 350°C. By using these reaction conditions, CB can be crushed into finer particles, and moreover, CB can be reacted with high grafting efficiency.
A graft polymer is obtained.

As a specific example of reacting CB and polymer (A), for example, 1 to 3000 parts by weight of one or more polymers (A) to 100 parts by weight of CB, preferably 5 parts by weight to 3000 parts by weight.
1000 parts by weight and 0 parts by weight of one or more polymers that do not fall under polymer (A) - 1000 parts by weight and 0 parts by weight of an organic solvent
200 parts by weight from 50℃ to 350℃, preferably from 100℃
Stir and mix at a temperature of 300°C. In this reaction, the pH of CB is an important factor; with highly reactive polymers containing oxazoline groups and aziridine groups, a graft compound can be easily obtained even if the pH is 8 or higher, but with polymers containing epoxy groups, If the reactivity is low, the pH of usable CB is 2 to 6.
Preferably the pH is in the range of 2 to 4.

The toner for developing electrostatic images of the present invention contains the CB graft polymer obtained by the above procedure, and the CB graft polymer or a mixture of the CB graft polymer and a polymer other than the polymer (A) is used. The finely pulverized toner can be used as it is as the electrostatic image developing toner of the present invention. Further, if necessary, after forming the CB graft polymer, a polymer other than the polymer (A) may be added, and this may be finely pulverized to form a toner for developing an electrostatic image. However, from the viewpoint of image fixability, it is preferable that a polymer other than the polymer (A) is always included, and it is particularly preferable that the polymer other than the polymer (A) is a thermoplastic polymer.

The content of CB in the toner for developing electrostatic charge images of the present invention is not particularly limited and can be set within a wide range depending on the purpose of use, but usually the CB content in the toner for developing electrostatic charge images is 1 to 20% by weight. %, particularly preferably 3 to 10% by weight.

The toner for developing electrostatic images of the present invention may optionally contain conventionally known additives such as charge control agents and anti-offset agents.

When forming an image using the electrostatic image developing toner of the present invention using an electrophotographic developing device,
Usually, magnetic fine particles are used as a two-component developer mixed with the toner, or as a one-component developer contained in the toner. The magnetic particles may be any material that exhibits magnetism or can be magnetized, such as metals such as iron, manganese, nickel, cobalt, and chromium, magnetite, maghemite, various ferrites, manganese alloys, and other ferromagnetic alloys. . In the case of a two-component developer, these magnetic fine particles are made into a fine powder with an average particle diameter of about 20 to 100 μm, more preferably 40 to 80 μm, and used as a carrier. The amount of magnetic fine particles used is usually in the total amount of developer.
The content is preferably 70 to 99% by weight, more preferably 90 to 97% by weight. In the case of a one-component developer, fine powder of magnetic fine particles having an average particle size of about 0.05 to 5 μm (more preferably 0.1 to 2 μm) can be used.
The amount of magnetic fine particles used is usually 1.5 to 70% of the total amount of developer.
Suitably, the amount is 25 to 45% by weight, more preferably 25 to 45% by weight.

(Effects of the Invention) The electrostatic image developing toner of the present invention has CB uniformly dispersed in the resin by using a CB graft polymer obtained by a specific method. is small, and
The charge distribution of toner particles is uniform, and a stable image without contamination can be formed, and an image with clear outline and extremely high contrast can be obtained.

Therefore, the toner for developing electrostatic images of the present invention can be used in a wide range of electrophotographic developing devices, such as laser printers, LED (light emitting diode) printers, liquid crystal,
It can be suitably used for printing in printers and the like.

(Examples) Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to the following Examples. All parts in the examples are by weight.

Synthesis Example 1 Polyvinyl alcohol was placed in a flask equipped with a stirrer, an inert gas introduction tube, a reflux condenser, and a thermometer.
200 parts of deionized water in which 0.1 part was dissolved was charged. A mixture of 8 parts of benzoyl peroxide dissolved in a polymerizable monomer consisting of 98 parts of styrene and 2 parts of isopropenyl oxazoline, which had been prepared in advance, was charged therein and stirred at high speed to form a uniform suspension. Next, the mixture was heated to 80° C. while blowing nitrogen gas, stirred at this temperature for 5 hours to carry out a polymerization reaction, and then cooled to obtain a polymer suspension. This polymer suspension was filtered, washed, and then dried to obtain a polymer having an oxazoline group as a reactive group.

Polymers with oxazoline groups as reactive groups
40 parts and 20 parts of CB (MA-600 manufactured by Mitsubishi Chemical Industries, Ltd.) using a Laboplastomill (manufactured by Toyo Seiki Co., Ltd.).
After kneading and reacting at 160° C. and 100 rpm, the mixture was cooled and pulverized to obtain CB graft polymer (1).

Synthesis Example 2 Synthesis Example 1 except that the polymerized monomers used were 75 parts of styrene, 22.5 parts of methyl methacrylate, and 2.5 parts of glycidyl methacrylate.
The same method was repeated to obtain a polymer having an epoxy group as a reactive group.

After kneading and reacting 45 parts of a polymer having an epoxy group as a reactive group and 15 parts of CB (MA-100R manufactured by Mitsubishi Chemical Industries, Ltd.) using a Laboplasto Mill at 220°C and 100 rpm. It was cooled and pulverized to obtain CB graft polymer (2).

Synthesis Example 3 The same method as in Synthesis Example 1 was repeated except that the polymerizable monomers used were 95 parts of styrene, 3 parts of n-butyl acrylate, and 2 parts of N-hydroxyethyl methacrylamide. A graft polymer (3) was obtained.

Synthesis Example 4 Toluene was placed in a flask equipped with a dropping funnel, a stirrer, an inert gas introduction tube, a reflux condenser, and a thermometer.
100 parts and 100 parts of methyl isobutyl ketone were charged, and heated to 80°C while blowing nitrogen gas.
97 parts of styrene prepared in advance and 2
-(1-aziridinyl)ethyl methacrylate 3
A mixture of 2 parts of benzoyl peroxide dissolved in a polymerizable monomer consisting of Obtained. 7,000 parts of methanol was added to this polymer solution, reprecipitation was performed, and then dried to obtain a polymer having an aziridine group as a reactive group.

Polymer 40 with aziridine groups as reactive groups
and 20 parts of CB (MA-600) were reacted in the same manner as in Synthesis Example 1, then cooled and pulverized to obtain a CB graft polymer.
(4) was obtained.

Synthesis Example 5 Add toluene to the same flask used in Synthesis Example 4.
Pour 217 parts and heat to 90℃ while blowing nitrogen gas.
heated to. Styrene prepared in advance
A mixture of 4.61 parts of mercaptoethanol and 1.32 parts of azobisisobutyronitrile dissolved in a polymerizable monomer consisting of 480 parts of n-butyl acrylate and 20 parts of n-butyl acrylate was added dropwise from the dropping funnel over 2 hours. The polymerization reaction was carried out by continuing stirring for a certain period of time. Next, 0.1 g of dibutyltin dilaurate and 2.38 g of 2,4-tolylene diisocyanate were added to 185.1 g of this reaction product (a solution containing a prepolymer having a hydroxyl group at the end) and reacted at 80°C for 30 minutes to react the end. A solution (non-volatile content: 70%) of a polymer having an isocyanate group as a functional group was obtained.

Add 57.1 parts of a solution (70% non-volatile content) of a polymer having an isocyanate group as a reactive group at the end and
CB (MA-100R) 20 pre-dried at 200℃ for 2 hours
The mixture was kneaded at 160° C. and 100 rpm using a Labo Plastomill to remove the solvent and a coolant, followed by a cooling agent and pulverization to obtain the CB graft polymer (5).

Comparative Synthesis Example 1 A flask similar to that used in Synthesis Example 1 was charged with 48 parts of styrene and 12 parts of CB (MA-600), heated to 140°C while blowing nitrogen gas, and stirred at this temperature for 5 hours. After performing the polymerization reaction, the mixture was cooled. After the reaction, 300 parts of toluene was added to the reaction product, and then 7000 parts of methanol was added to cause reprecipitation, thereby obtaining grafted CB (1) for comparison.

Synthesis Example 6 40 parts of the polymer having an oxazoline group as a reactive group obtained in Synthesis Example 1, 20 parts of CB (MA-600), and 10 parts of polystyrene (Styron, manufactured by Asahi Kasei Corporation) were heated at 160°C and 100 rpm. After kneading and reacting under the following conditions, it is cooled and crushed to contain polystyrene.
A CB graft polymer (6) was obtained.

Example 1 CB graft polymer (1)30 obtained in Synthesis Example 1
part, 70 parts of styrene-butyl methacrylate copolymer (manufactured by Sanyo Chemical Co., Ltd., Hymer SBM73) and a charge control agent (manufactured by Hodogaya Chemical Co., Ltd., Aizen Spiron).
Black TRH) were stirred and mixed in a Henschel mixer, kneaded for 20 minutes at 160°C using a roll mill, cooled, and coarsely ground using a continuous vibration mill. continue,
After finely pulverizing the powder using a jet mill, it was classified to obtain a toner (1) for electrostatic charge development having a particle size of 3 to 15 μm. Average particle size for 5 parts of this electrostatic image developing toner (1)
A developer (1) was prepared by uniformly mixing with 95 parts of iron powder carrier of 50 to 80μ.

Using this developer (1), copying machine (Recopy FT-
4630 manufactured by Ricoh Co., Ltd.), an image with clear outlines and extremely high contrast was obtained. Furthermore, even after printing 200,000 images, we were able to obtain almost unchanged good images.

Example 2 In Example 1, the blending during stirring and mixing using a Henschel mixer was changed to 30 parts of the CB graft polymer (2) obtained in Synthesis Example 2, and a styrene resin (manufactured by Etsu Petrochemical Co., Ltd., Picolastic D-125). 70 parts and a charge control agent (manufactured by Hodogaya Chemical Industry Co., Ltd., Aizen)
Spiron Black TRH) The same operation as in Example 1 was repeated except that the particle size was 5 to 15 μm.
A toner (2) for developing an electrostatic image was obtained, and a developer (2) was further prepared.

When this developer (2) was used for the same evaluation as in Example 1, an image with clear outlines and extremely high contrast was obtained. Furthermore, even after printing 200,000 images, we were able to obtain almost unchanged good images.

Example 3 In Example 1, the blending during stirring and mixing using a Henschel mixer was as follows: 30 parts of the CB graft polymer (3) obtained in Synthesis Example (3), an epoxy resin (Siel Chemical Co., Ltd.)
(manufactured by Hodogaya Chemical Co., Ltd., Epon 1004) 70 parts and a charge control agent (manufactured by Hodogaya Chemical Industry Co., Ltd., Aizen Spiron Blcack TRH) 2
The same operation as in Example 1 was repeated except that the toner for electrostatic image development with a particle size of 5 to 15 μm was prepared.
(3) was obtained, and a developer (3) was further prepared.

When this developer (3) was used to produce an image using a copying machine (Model DC-113, manufactured by Sanda Kogyo Co., Ltd.),
An image with clear outlines and extremely high contrast was obtained. Furthermore, even after printing 200,000 images, we were able to obtain almost unchanged good images.

Example 4 In Example 1, the blending during stirring and mixing using a Henschel mixer was changed to 30 parts of the CB graft polymer (4) obtained in Synthesis Example 4, styrene-butyl methacrylate copolymer (Himer SBM73 manufactured by Sanyo Chemical Co., Ltd.)
68.5 parts, 1.5 parts of low molecular weight polyethylene (manufactured by Mitsui Petrochemical Industries, Ltd., Mitsui Hiwax 4052E) and a charge control agent (manufactured by Hodogaya Chemical Industries, Ltd., Aizen Spiron)
The same operation as in Example 1 was repeated except that the toner (4) for developing an electrostatic image having a particle size of 5 to 15 μm was obtained, and a developer (4) was further prepared.

When this developer (4) was evaluated in the same manner as in Example 3, an image with clear outlines and extremely high contrast was obtained.
Furthermore, even after printing 200,000 images, the images remained nearly unchanged.

Example 5 In Example 1, the blending during stirring and mixing using a Henschel mixer was changed to 30 parts of the CB graft polymer (5) obtained in Synthesis Example 5, and 40 parts of polyester resin (manufactured by Dainippon Ink Co., Ltd., PLASDIC-S1001). , styrene-butyl methacrylate copolymer (Sanyo Chemical Co., Ltd.)
(manufactured by Hodogaya Chemical Co., Ltd., Aizen Spiron Black) and charge control agent (manufactured by Hodogaya Chemical Co., Ltd., Aizen Spiron Black)
The same operations as in Example 1 were repeated except that 2 parts of TRH were used to obtain an electrostatic image toner (5) having a particle size of 5 to 15 μm, and a developer (5) was further prepared.

When this developer (5) was evaluated in the same manner as in Example 1, an image with clear outlines and extremely high contrast was obtained. Also
Even after printing 200,000 images, we were able to obtain almost unchanged good images.

Example 6 The blending at the time of stirring and mixing using a Henschel mixer in Example 1 was changed to 40 parts of the CB graft polymer (6) containing polystyrene obtained in Synthesis Example 6, styrene-butyl methacrylate copolymer (Sanyo Chemical Co., Ltd.)
(manufactured by Hodogaya Chemical Industry Co., Ltd., Aizen Spiron Black) 60 parts
TRH) Repeat the same procedure, except for using 2 parts, and create toner for electrostatic image development with a particle size of 5 to 15 μm (6).
I got it. Furthermore, the developer (6) was adjusted.

When this developer (6) was evaluated in the same manner as in Example 3, an image with clear outlines and extremely high contrast was obtained.
Furthermore, even after printing 200,000 images, we were able to obtain almost unchanged good images.

Example 7 90 parts of the polymer having an oxazoline group as a reactive group obtained in Synthesis Example 1, CB (Mitsubishi Kasei Corporation MA)
−600) 10 parts and charge control agent (Hodogaya Chemical Industry Co., Ltd.)
2 parts of Aizen Spiron Black TRH) were heated to 160°C using Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.).
The mixture was kneaded and reacted at 100 rpm. The kneaded material obtained by cooling is pulverized and classified to have a particle size of 5 to 5.
A toner (7) for developing electrostatic images of 15 μm was obtained. A developer (7) was prepared by uniformly mixing 3 parts of this electrostatic image developing toner (7) with 97 parts of a ferrite carrier having a particle size of 50 to 80 μm.

When this developer (7) was evaluated in the same manner as in Example 1, an image with clear outlines and extremely high contrast was obtained. Furthermore, even after printing 200,000 images, good images were obtained that remained almost unchanged.

Example 8 In Example 7, 20 parts of the polymer having an epoxy group as a reactive group obtained in Synthesis Example 2 and CB (Mitsubishi Kasei Corporation) were mixed during kneading using Labo Plastomill.
(manufactured by Sanyo Chemical Co., Ltd., MA-100R) 10 parts, styrene-butyl methacrylate copolymer (manufactured by Sanyo Kasei Co., Ltd., Hymer
The same operation as in Example 7 was repeated except that 70 parts of SBM73) and 2 parts of charge control system (manufactured by Hodogaya Chemical Industry Co., Ltd., Aizen Spiron Black TRH) were used to develop an electrostatic charge image with a particle size of 5 to 15 μm. A toner (8) was obtained. 5 parts of this electrostatic image developing toner (8) and 95 parts of iron powder carrier were uniformly mixed to prepare a developer (8). When this developer (8) was evaluated in the same manner as in Example 3, an image with extremely high contrast was obtained. Furthermore, even after printing 200,000 images, the images remained nearly unchanged.

Example 9 CB graft polymer (3) obtained in Synthesis Example 330
parts, 70 parts of styrene-butyl methacrylate copolymer (manufactured by Sanyo Chemical Co., Ltd., Higher SBM73), charge control agent (manufactured by Hodogaya Chemical Co., Ltd., Aizen Spiron)
Black TRH) 2 parts and magnetic particles (Toda Kogyo Co., Ltd.)
After thoroughly mixing 40 parts of Ferrite EPT-500) in a blender, the mixture was heated and kneaded in a roll mill at 150°C for 15 minutes, cooled, crushed in a hammer mill, and then finely pulverized in an air jet type pulverizer. Further, air classification was performed, and 5 to 25 μm was selected, and 0.4 part of hydrophobic colloidal silica R-972 (manufactured by Nippon Aerosil Co., Ltd.) was mixed in a sample mill to prepare a one-component magnetic toner.

When the resulting single-component magnetic toner was imaged using a commercially available copying machine (trade name NP-150Z, manufactured by Canon Inc.), an image with clear outlines and extremely high contrast was obtained. Furthermore, even after printing 200,000 images, good images were obtained that remained almost unchanged.

Comparative Example 1 Except for using 10 parts of CB (MA-600) instead of 30 parts of CB graft polymer (1) in Example 1,
A comparative electrostatic image developing toner (1) was obtained by repeating the same operations as in Example 1, and a comparative developer (1) was also prepared.

When this comparative developer (1) was evaluated in the same manner as in Example 1, the images obtained were unclear with significant fogging in the non-image areas, and the images were not clear due to repetition. The exposure caused significant contamination of the photosensitive area.

Comparative Example 2 The same operations as in Example 2 were repeated except that the comparative grafted CB (1) obtained in Comparative Synthesis Example 1 was used instead of the CB grafted polymer (2) in Example 2. A toner (2) for developing electrostatic images was obtained, and a comparative developer (2) was also prepared.

When this comparative developer (2) was used for evaluation in the same manner as in Example 1, the obtained images were unclear due to fogging in non-image areas, and it was difficult to produce repeated images. This resulted in significant contamination of the photosensitive area.

Claims (1)

[Claims] 1 Carbon black contains a polymer having one or more reactive groups selected from aziridine group, oxazoline group, N-hydroxyalkylamide group, epoxy group, and isocyanate group in the molecule.
A toner for developing electrostatic images containing a carbon black graft polymer obtained by mixing and stirring under conditions of 50°C to 350°C and reacting.