JP2547014B2 - 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 toner particle size, 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 is used. Not only is it difficult to manufacture with high yield, but the fixing property of the image when used as a developer is poor, or the image is contaminated due to offset development, etc., and it is possible to avoid defects such as low resolution and fogging. It was difficult.

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

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 developing an electrostatic charge image, comprising associated particles of primary particles, colorant particles, fixability improving agent particles, and secondary particles containing an optional charge control agent.

The primary particles of the polymer having a polar group used in the present invention and the fixing improver particles are 0.05 to 0.5μ, preferably 0.1 to 0.
It is a particle of a thermoplastic polymer having an average particle diameter of 3μ and is generally suitably obtained by an emulsion polymerization method. The secondary particles constituting the above-mentioned associated particles which are the toners of the present invention are 0.
The colorant particles having an average particle size of 01 to 0.5, preferably 0.03 to 0.1 μ, the primary particles of the polymer having a polar group and the fixability improving particles are ionic bond, hydrogen bond, metal coordination bond, weak acid. Particles that are aggregated by a weak group bond or a bond force such as the Van der Waals force, and are generally 0.5 to 5
It has an average particle size of μ, preferably 1 μ 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, at least a part of the contact portion between the secondary particles constituting the above-mentioned associated particles, preferably the majority of the contact portion between the secondary particles, the associated particles are film-fused. Used.

The associated particles, which are the toner of the present invention, have a polar group-containing polymer in an amount of 20 to 20 per the total amount of the polymer having a polar group and the colorant.
99.9% by weight, preferably 30-98% by weight, most preferably
40-95% by weight and 80-0.1% by weight of colorant, preferably 7
0 to 2% by weight, most preferably 60 to 5% by weight, and as the fixability improving agent, the total of a polymer having a polar group and a colorant.
The fixability improving agent is contained in an amount of 0.1 to 40 parts by weight, preferably 0.5 to 30 parts by weight, and more preferably 1 to 20 parts by weight per 100 parts by weight.

A preferable 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.

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.

The colorant used in the present invention, an inorganic pigment or,
Organic pigments and organic dyes, preferably inorganic pigments or organic pigments are used, but one or more pigments or / and one or more dyes may be used in combination as required.

As described above, the toner of the present invention contains a charge control agent, a magnetic material and the like, 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 chlorine paraffins, chlorinated polyesters, polyesters having an excess of acid groups, sulfonylamines of copper phthalocyanine 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 fluidizing agent, fine powder of hydrophobic silica, titanium oxide, aluminum oxide or the like can be exemplified, and toner 100 The amount is 0.01 to 5 parts by weight, preferably 0.1 to 1 part by weight.

As the fixing property improving agent used in the present invention, one kind or two or more kinds of fixing property improving agents may be combined. Preferred examples of the fixability improver used in the present invention include:
Olefin resin (low molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide, polytetrafluoroethylene, etc.), epoxy resin, polyester resin, styrene-
Butadiene copolymer (monomer ratio 5 to 30:95 to 70), olefin copolymer (ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid Ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ionomer resin), polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid modified phenol resin, phenol modified terpene resin, etc. These resins, preferably olefinic resins, are preferably used as an aqueous dispersion emulsion.

Specific examples of the fixability improving agent used in the present invention include E-4A (polyethylene wax emulsion) commercially available under the trade name "HYTEC" (manufactured by Toho Chemical Industry Co., Ltd.),
E-4B (same), E-5403A (same), E-5403B (same), E
-68A (same), E-103A (same), E-103N (same), E-4
Examples include 33N (polypropylene wax emulsion).

The preferred method for producing the toner of the present invention is as follows. To the emulsion of a polymer having an acidic polar group or a basic polar group obtained by emulsion polymerization, the required amount of colorant powder, fixability improving agent and optional charge control agent are added and mixed to uniformly disperse for 0.5 to 4 hours. , Preferably 1
When stirring was continued for 3 hours, the primary particles of the polymer having polar groups, the fixing fixative particles and the colorant particles gradually aggregated to 0.5.
Grow to secondary particles with an average particle size of ~ 5μ. Such a dispersion is further left as it is for 0.5 to 3 hours, preferably 1 to
If stirring is continued for 2 hours, the secondary particles will be further aggregated and 5 to 25μ
Grows into associated particles having an average particle size of. In the most preferred method for producing the toner of the present invention, the dispersion liquid thus produced is further added to the polymer having a polar group at a temperature of 20 ° C. higher than the glass transition temperature of the polymer for 1 to 6 hours. Is 2
When stirring is continued for up to 4 hours, associated particles in which at least a part of the contact portion between the secondary particles are film-fused are formed. Since such associated particles have a film-forming fusion between the secondary particles, they are hardly disintegrated during storage, transportation, production of the developer, etc., and thus are particularly suitable as a developer for developing an electrostatic image. It is suitable.

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 functions 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, not only the image fixability is very good as compared with the conventional product, but also the offset is obtained. It has an excellent effect that the resolution is remarkably improved without development and the occurrence of fogging is almost eliminated. Further, the manufacturing method such as pulverization and classification is simplified as compared with the conventional method, and the required yield of toner particles is Since it is also high, it is effective in terms of economic efficiency.

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 The above monomer mixture is water 100 parts 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%.

Toner Preparation (1) Acidic polar group-containing resin emulsion 120 parts Magnetite 40 parts Nigrosine dye (Bontron N-04) 5 parts Carbon black (diamond black # 100) 5 parts Wax emulsion (HYTECE-433N) (Fixability improver) 20 parts Water 380 parts Disperse and mix the above mixture with a slasher at about 30 ° C.
Hold for 2 hours. Then, it was heated to 70 ° C. with further stirring and kept for 3 hours. During this time, it was confirmed by observing with a microscope that the complex of the resin particles, the fixability improving agent particles, and the magnetite particles grew to about 10 μm. After cooling, the resulting liquid dispersion is filtered with Buchner filter and washed with water at 50 ° C.
It was vacuum dried for 10 hours.

To 100 parts by weight of the toner thus obtained, 0.5 parts by weight of silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) as a fluidizing agent was added and mixed to prepare a test developer.

The polymer used in this toner had a Tg of 43 ° C., a gelation degree of 8%, a softening point of 142 ° C., and an average particle diameter of 12 μm.

When the above developer was put in 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 to 7 The same operation as in Example 1 was repeated using the monomer composition and fixing property improver shown in Table 1. Table 2 shows the results. The meanings of the abbreviations used in Table-1 are shown below.

2EHA; 2-ethylhexyl acrylate MAA; Methacrylic acid BQA; 2-Hydroxypropyl-N, N, N-trimethylammonium chloride acrylate VP; Vinyl pyridine Example 5 After preparing an acidic polar group-containing resin emulsion similar to Example 1 The following operations were performed during toner adjustment.

Preparation of toner (2) Emulsion containing acidic polar group resin of Example 1 184 parts Chromium dye (Bontron E-81) 1 part Carbon black (Regal 330R) 7 parts Wax emulsion (HYTEC S-3121) (Fixability improver) 15 parts water 307 parts The above mixture was treated in the same manner as in Example 1 to prepare a test toner. The polymer obtained had a Tg of 42 ° C., a gelation degree of 9%, a softening point of 132 ° C., and an average particle size of the toner was 10.5.
μm. 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. The results are shown in Table-2.
Shown in

Examples 6 and 7 The same operation as in Example 5 was repeated using the monomer composition shown in Table 1. Table 2 shows the results.

Example 8 During the reaction of forming associated particles in Example 1, the temperature was maintained at 70 ° C. for 2 hours instead of at 70 ° C. for 2 hours. As a result, particle growth was controlled and a toner having an average particle size of 5 μm was obtained at a yield of 60%. Was obtained. When a copying test was carried out using this toner, 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 and the fixability improving agent emulsion of Example 1 were spray dryer (manufactured by Ashizawaniro atomizer, Mobile Miner) at an inlet temperature of 120 ° C, an outlet temperature of 90 ° C, a supply rate of 1.5 / min, and an atomizer of 3 × 10 ⁴ rpm.
The resin was obtained by drying under the operating conditions. 60 parts of this resin,
40 parts magnetite, Nigrosine dye (Bontron N-0
4) 5 parts, carbon black (diamond black # 100) 5
Part was melt-kneaded and pulverized to obtain a toner having an average particle size of 5 μm. The yield at this time was 35%.

To 100 parts by weight of the obtained toner, 0.5 parts by weight of silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was added and mixed as a fluidizing agent to prepare a test developer.

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

Comparative Example 3 A resin composition as shown in Table 1 was used, and the same procedure as in Example 1 was performed without adding the fixability improver. Tg 45 ° C., gelation degree 5%, comparison point 147 ° C., average particle size 12.0 μm Toner was obtained. When a copying test similar to that in Example 1 was conducted using this toner, an image with extremely poor fixing property was obtained.

Copy image resolution evaluation method Copy Data Quest's test pattern AR-4,
The number of lines per 1 mm was visually confirmed to evaluate the resolution. In this evaluation method, with the resin composition of Table-1, it can be judged that the resolution of 6.3 or more is good, and the resolution of 3.6 or less is bad.

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.

Copy image fixing rate evaluation method The test pattern was copied, the solid black portion was rubbed 5 times with sand eraser, and the fixing ratio was defined as the reflectance ratio before and after rubbing using the reflectance meter. It can be judged that the fixing rate is 85% or more, and the fixing rate is 70% or less.

Average particle size The average particle size of 10,000 toner particles is measured with a Coulter Counter TA-II (manufactured by Nikkaki Co., Ltd.).

Claims (2)

(57) [Claims] 1. An association particle of primary particles of a polymer having an acidic polar group or a basic polar group, colorant particles, fixability improving agent particles, and secondary particles containing an optional charge control agent. 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 fixability improving agent particles are an olefin resin emulsion.