JP2557646B2 - Toner for electrostatic image development - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like, and a method for producing the toner.

2. Description of the Related Art Conventionally, a toner that has been widely used in the past is obtained by dry-blending a styrene / acrylate copolymer powder obtained by suspension polymerization with a colorant such as carbon black, an optional charge control agent and / or a magnetic material. It has been produced by melt-kneading with a post-extruder or the like, and then crushing and classifying (see Japanese Patent Laid-Open No. 51-23354).

However, the conventional toner obtained by the melt-kneading-pulverization method as described above has a limitation in controlling the particle size of the toner, and a toner having an average particle size of substantially 10 μm or less, particularly 8 μm or less, and particularly 5 μm or less. Although it is difficult to manufacture the toner with good yield, the cleaning property is poor and the carrier concentration on the surface of the photoconductor and the toner concentration in the developer may change, resulting in significant image defects such as bleeding and fogging. It was difficult to avoid the drawbacks.

OBJECT OF THE INVENTION The present invention greatly improves the above-mentioned drawbacks of toners which have been widely used in the past, and by using a novel manufacturing method, the toner is cheaper than the conventional toner and has good cleaning property. The purpose is to provide a good toner.

Features of the present invention The toner for developing an electrostatic image of the present invention comprises a polymer having an acidic polar group or a basic polar group (hereinafter referred to as "polymer having a polar group"), preferably a polymer having an acidic polar group. A toner for electrostatic charge images, characterized in that associated particles of secondary particles containing primary particles, colorant particles, and an optional charge control agent are surface-treated with a surface treatment agent.

The primary particles of the polymer having a polar group used in the present invention are particles of a thermoplastic polymer having an average particle diameter of 0.05 to 0.5μ, preferably 0.1 to 0.3μ, and are generally suitably obtained by an emulsion polymerization method. To be The secondary particles constituting the above-mentioned associated particles, which are the toner of the present invention, are 0.01 to 0.5, preferably
The colorant particles having an average particle diameter of 0.03 to 0.1μ and the primary particles of the polymer having a polar group have ionic bonds, hydrogen bonds, metal coordination bonds, weak acid-weak group bonds, or van der Waals forces, etc. The particles are aggregated by the binding force and generally have an average particle size of 0.5 to 5 μ, preferably 1 to 4 μ.

The associated particles of the present invention are indefinite particles produced by agglomeration of the above secondary particles, and the average particle size thereof is generally 3 to 25.
μ, preferably 5 to 15 μ, and most preferably 5 to 13 μ.

In a preferred embodiment of the present invention, associative particles in which at least a part of the contact parts between the secondary particles constituting the above-mentioned associated particles, preferably most of the contact parts between the secondary particles are fused by film formation are used. To be

The associative particles of the toner of the present invention contain a polymer having a polar group and a polymer having a polar group in an amount of 20 to 9 per total of the colorant.
9.9% by weight, preferably 30-98% by weight, most preferably 4
0 to 95% by weight and 80 to 0.1% by weight of colorant, preferably 70
.About.2% by weight, most preferably 60 to 5% by weight.

A preferred example of the polymer having a polar group used in the present invention is a copolymer of styrenes, alkyl (meth) acrylate and a comonomer having an acidic polar group or a basic polar group (hereinafter referred to as "comonomer having a polar group"). Is.

In the present specification, the term "colorant" is used to mean a coloring additive that gives the developer a color required for an electrostatic image developer, and a magnetic substance such as magnetite or a nigrosine dye. An additive that imparts a property other than a colorant such as a magnetic property or a charge controllability to the developer, such as a charge control agent, is included in the “colorant” if it imparts the desired colorability to the developer. It is a thing.

As the colorant used in the present invention, an inorganic pigment or an organic pigment and an organic dye, preferably an inorganic pigment or an organic pigment is used, but one or more pigments or / and one or more dyes are required. You may use it in combination according to.

As described above, the toner of the present invention contains a charge control agent, a magnetic material, etc., if necessary. Examples of such a charge control agent include a nigrosine-based electron-donating dye for plus, other metal salt of naphthenic acid or higher fatty acid, alkoxylated amine, quaternary ammonium salt, alkylamide, chelate, pigment, fluorine treatment activator. Such,
For minus, electron-accepting organic complexes, other chlorinated paraffins, chlorinated polyesters, polyesters having an excess of acid groups, copper phthalocyanine sulfonylamines and the like can be exemplified.

Further, the toner of the present invention can be used together with an additive such as a fluidizing agent if necessary, and as such a fluidizing agent, fine powder of hydrophobic silica, titanium oxide, aluminum oxide or the like can be exemplified, and the toner 100 The amount is 0.01 to 5 parts by weight, preferably 0.1 to 1 part by weight.

The cleaning property improver used in the present invention is on the surface of toner particles and has poor cleaning property in a copying test due to the action of cleaning effect, roller effect, etc., and contamination such as filming of carrier, photoconductor, etc. Is effectively prevented, the decrease in image density and the occurrence of fogging are suppressed, and the cleaning property is improved.

Examples of the cleaning property improver suitably used in the present invention include acrylic resin powder and metal oxide powder, and one or more kinds of cleaning property improver may be combined as necessary. The primary particles of the cleaning property improving agent preferably used in the present invention are fine powders having an average particle diameter of 0.1 to 1000 mμ, preferably 1 to 500 mμ, and more preferably 5 to 100 mμ, and may be generally commercially available. .

As the acrylic resin powder, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate,
N-Butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, α-chloromethyl acrylate , Methylmethacrylate, ethylmethacrylate, propylmethacrylate, n-butylmethacrylate, isobutylmethacrylate, n-octylmethacrylate, dodecylmethacrylate, laurylmethacrylate, 2-methacrylate
Resin powders obtained from monomers such as ethylhexyl and stearyl methacrylate can be mentioned.

Further, as the metal oxide powder, cerium, zinc,
Metal oxide powders such as magnesium, calcium, cadmium, lead, iron, nickel, cobalt or copper can be mentioned.

The toner of the present invention has a cleaning property improver of 0.01 to 25 parts by weight, more preferably 0.1 to 1 per 100 parts by weight of associated particles.
Used 0 parts by weight.

The preferred method for producing the toner of the present invention is as follows. A required amount of colorant powder and optional charge control agent are added to and mixed with an emulsion of a polymer having an acidic polar group or a basic polar group obtained by emulsion polymerization, and the mixture is uniformly dispersed for 0.5 to 4 hours, preferably 1 When the stirring is continued for 3 hours, the primary particles of the polymer having a polar group and the colorant particles are gradually aggregated to grow into secondary particles having an average particle size of 0.5 to 5 μ. When such a dispersion is further stirred as it is for 0.5 to 3 hours, preferably 1 to 2 hours, the secondary particles further aggregate and grow into associated particles having an average particle diameter of 5 to 25 μm. In the most preferable production method of the toner of the present invention, the dispersion liquid thus produced is further heated at a temperature 20 ° C. higher than the glass transition point of the polymer having a polar group to 20 ° C. for 1 to 6 hours, preferably When stirring is continued for 2 to 4 hours, associated particles in which at least a part of the contact portions between the secondary particles are film-fused are formed.

Buchner filtration of the liquid dispersion of the obtained associated particles,
After washing with water, the polymer having a polar group has a glass transition point to 2 to 20 ° C. lower than the glass transition point for 1 to 48 hours, preferably 5
Vacuum drying or hot air drying for -20 hours to obtain a dry powder of associated particles.

A required amount of acrylic resin powder in the obtained associated particles,
A toner of the present invention is obtained by adding a cleaning property improver such as metal oxide powder and mixing and dispersing with a Henschel mixer or the like for surface treatment.

The toner of the present invention is mixed with a carrier such as iron or glass beads to be a developer, but when the toner itself already contains ferrite or the like as a colorant, the ferrite or the like also acts as a carrier. Therefore, in that case, the toner can be used as a developer as it is. As the carrier, iron powder having a negative triboelectrification characteristic by resin coating, preferably fluorine resin coating, is particularly suitable.

EFFECTS OF THE INVENTION The toner of the present invention has a relatively narrow particle size distribution and a relatively small average particle size. Therefore, when it is used as an electrostatic image developer, the resolution is remarkably improved and the occurrence of fogging is almost eliminated. It has an excellent effect that it does not need to be crushed and the manufacturing method is simpler than the conventional method such as crushing and classification is not required and the yield of required toner particles is high, so that it is also excellent in economic efficiency. It plays.

Further, by subjecting the toner of the present invention to a surface treatment with a cleaning property improver, a so-called filming phenomenon, in which a part of the toner component adheres to the surface of the photoconductor or the carrier, is prevented, and not only the cleaning property becomes good. ,
The effect of remarkably improving the fluidity, developability, fixability and transferability can be obtained.

The present invention will be specifically described below with reference to examples. In addition, unless otherwise specified, the quantities are indicated by weight.

Example 1 Preparation of acidic polar group-containing polymerized resin Styrene monomer (ST) 60 parts Butyl acrylate (BA) 40 parts Acrylic acid (AA) 8 parts Water 100 parts of the above monomer mixture Nonionic emulsifier (Emulgen 950) 1 part Anion An emulsifier (Neogen R) (1.5 parts) and potassium persulfate (0.5 parts) were added to an aqueous mixture, and the mixture was polymerized under stirring at 70 ° C. for 8 hours to obtain an acidic polar group-containing resin emulsion having a solid content of 50%.

Preparation of toner (1) Acid polar group-containing resin emulsion 120 parts Magnetite 40 parts Nigrosine dye (Bontron N-04) 5 parts Carbon black (diamond # 100) 5 parts Water 380 parts While dispersing and stirring the above mixture with a slasher. About 30
C. for 2 hours. Then, with further stirring, 70 ℃
It was heated to and held for 3 hours. While observing with a microscope,
Complex of resin particles and magnetite particles is about 10
It was confirmed to grow to μ. After cooling, the obtained liquid dispersion was subjected to Buchner filtration, washed with water, and vacuum dried at 40 ° C. for 10 hours.

To 100 parts by weight of the thus obtained toner, 0.5 part by weight of cerium oxide as a cleaning property improver was added and mixed to obtain a test developer.

The Tg of the above polymer used in this toner was 45 ° C., the degree of gelation was 5%, the softening point was 148 ° C., and the average particle size of the toner was 12 μ.

When the above developer was put into a commercially available copying machine (NP-270Z manufactured by Canon Inc.) and copying was performed, a copy image having high density and less fog was obtained. The results are shown in Table-2.

Examples 2 and 3 Using the monomer composition cleaning property improvers shown in Table-1, the same operation as in Example 1 was repeated. Table of results
It is shown in FIG. The meanings of the abbreviations used in Table-1 are shown below.

2EHA; 2-ethylhexyl acrylate Example 4 After preparing the same acidic polar group-containing resin emulsion as in Example 1, the following operations were carried out during toner preparation.

Preparation of toner (2) Acidic polar group-containing resin of Example 1 Emulsion 184 parts Chromium dye (Bontron S-34) 1 part Carbon black (Legal 330R) 7 parts Water 307 parts The same procedure as in Example 1 Then, the test toner was prepared. The Tg of the obtained polymer was 45 ° C, the gelation degree was 5%, the softening point was 147 ° C, and the average particle diameter of the toner was 10.5 mμ.
Met. When this toner was put in a commercially available copying machine (Toshiba made Rhodry BD-4140) and copying was performed, a copy image having high density and less fog was obtained. Table 2 shows the results.

Example 5 When the associated particle formation reaction in Example 1 was carried out by heating at 70 ° C. for 2 hours instead of at 70 ° C. for 2 hours, the particle growth was controlled and the yield was 60% and the average particle size was 5 mμ. was gotten. A copying test was conducted using the associated particles as a toner in the same manner as in Example 1. As a result, an image having very good resolution, high density and little fog was obtained.

Comparative Example 1 As shown in Table 1, when a resin emulsion obtained by polymerizing without adding AA which is an acidic polar group monomer in the resin monomer composition of Example 1 was used, there was no growth of associated particles and a test toner was obtained. I couldn't get it.

Comparative Example 2 The resin emulsion of Example 1 was sprayed with a spray dryer (Ashizawa Niro atomizer, Mobile Miner) at an inlet temperature of 120 ° C, an outlet temperature of 90 ° C, and a supply rate of 1.5 / mi.
n, dried under the operating conditions of atomizer 3 × 10 ⁴ rpm,
A resin was obtained. 60 parts of this resin, 40 parts of magnetite, 5 parts of Nigrosine dye (Bontron N-04) and 5 parts of carbon black (Diablack # 100) were melt-kneaded and pulverized to obtain a toner having an average particle diameter of 5 mμ. The yield at this time was 35%.

To 100 parts by weight of the obtained toner, 0.5 part by weight of cerium oxide as a cleaning property improver was added and mixed to obtain a test developer.

This developer had very poor fluidity. When a copying test similar to that of Example 1 was conducted using this developer, an image with very large fog was obtained.

Comparative Example 3 The same operation as in Example 1 was carried out to obtain an associated particle composition as shown in Table 1, and a toner having an average particle size of 12.0 mμ was obtained without adding a cleaning property improver. A similar copying test was conducted using this toner. Table 2 shows the results.

Duplicate image resolution evaluation method Duplicate the data quat company test pattern AR-4,
The number of lines per 1 mm was visually confirmed to evaluate the resolution. In this evaluation method, the resin composition shown in Table 1
It can be judged as good when 6.3 or more, and as bad when 3.6 or less.

Copy image fog evaluation method: Using a Murakami Color Laboratory CM-53P reflectometer, the reflectivity of the blank paper before copying and the reflectivity of the non-character part after copying were compared at a light angle of 45 °, and the reflectivity was compared. The fog density (%) was defined as a ratio. It can be judged that the fog density is 0.7 or less and the fog is good, and that the fog density is 1.0 or more is bad.

Cleaning Method Evaluation Method In the copying test of each example, after continuously copying 3,000 sheets, the surface of the photoconductor of the copying machine was cleaned with degreasing noodle, and the cleaning property was evaluated from the contaminated state of the degreasing noodle.

A: No degreasing noodle deposits (good cleaning ability) B: Good cleaning ability C; Medium D; 〃 Bad E; Toner adheres to the entire degreasing noodles (worst cleaning ability) Average particle size Coulter Counter TA-II [ Manufactured by Nikkaki Co., Ltd.] to measure the average particle size of 10,000 toner particles.

Claims (3)

(57) [Claims] 1. Surface treatment of a primary particle and a colorant particle of a polymer having an acidic polar group or a basic polar group, and associated particles of a secondary particle containing an optional charge control agent with a cleaning property improver. A toner for developing an electrostatic charge image, characterized by: 2. The toner for developing an electrostatic charge image according to claim 1, wherein the cleaning property improver is an acrylic resin powder. 3. The toner for developing an electrostatic charge image according to claim 1, wherein the cleaning property improver is a metal oxide powder.