JP2697043B2 - Toner for developing electrostatic images - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner used in electrophotography, electrostatic recording, and the like.

(Prior Art) In electrophotography, a photoconductive material such as selenium is used as a photoreceptor, an electric latent image is formed by various methods, and toner is applied to the latent image by a magnetic brush developing method or the like. A method of attaching and visualizing the image is generally adopted. The developing toner used there holds positive or negative charges according to the polarity of the electrostatic latent image to be developed by various friction charging methods.

By the way, the charging performance of the developing toner can be secured to some extent by the thermoplastic resin which is a main component of the toner, but is not sufficient. When the chargeability of the toner is low, problems such as fogging and other shortcomings in image characteristics and short life occur. Therefore, the above problem is solved by adding a charge control agent to the toner.

(Problems to be Solved by the Invention) As a charge control agent for imparting a positive charge, quaternary ammonium salts can be mentioned (for example, JP-A-49-51).
No. 951).

The present inventors have investigated the relationship between the uniform dispersion of the charge control agent in the toner, mainly the quaternary ammonium salts, and the chargeability, charge exchangeability, and stability over time of the toner. The toner has poor charge exchange properties,
Further, it was noticed that the toner having excellent charge exchange properties had low charging ability.

If the chargeability is low, fogging occurs early and there is a problem that the inside of the machine is contaminated.If the charge exchangeability is low, the triboelectric charge amount varies among the toner particles, and the charge characteristic becomes poor. In addition to being unstable, there is a problem that the charge decay is remarkable when a new toner is added, and the aging stability and the environmental stability are lacking.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a toner for developing an electrostatic image having both high chargeability and excellent charge exchangeability.

(Means for Solving the Problems) The present invention relates to (1) a toner for developing an electrostatic image containing a binder resin, a colorant and a charge control agent; 95% has a small dispersion diameter of 0.3 μm or less, and 5 to 20% has a large dispersion diameter of 0.5 μm or more, and (2) charge control. Among the agents, a quaternary ammonium salt-type charge control agent is used as small dispersion particles, and a quaternary ammonium salt-type charge control agent or a metal complex charge control agent is used as large dispersion particles. (1) The electrostatic image developing toner according to (1) above.

(Effects) The present inventors first disperse the charge control agent uniformly in the toner, and particularly, by controlling the average dispersion diameter in the toner to 0.5 μm or less, the electrostatic charge having excellent charge exchange property. Propose a toner for image development. If the average dispersion diameter exceeds 0.5 μm, there is a disadvantage that the charge exchangeability decreases and the variation in charging ability increases. However, the dispersion diameter of the charge control agent
If the thickness is 0.5 μm or less, there is a problem that the charge exchangeability is high but the charging ability is low.

Therefore, in the present invention, the majority of the charge control agent-dispersed particles are 0.
By making the dispersion diameter as small as 3 μm or less, excellent charge exchangeability is ensured, and by making a part thereof exist as a large dispersion diameter, an attempt is made to secure high chargeability. In order to impart such properties to the toner, 78 to 95% of the charge control agent dispersed particles having a dispersion diameter of 0.3 μm or less are present, and the charge control agent dispersed particles having a dispersion diameter of 0.5 μm or more are 5 to 20%. % Must be present.

The dispersion diameter of the charge control agent in the toner refers to the toner kneaded material before pulverization, which is the last step of the toner production method, of about 2 μm.
It can be cut into a thickness of μm, observed with a polarizing microscope (Nikon XTP-11), photographed in a polarization mode using the same photographing apparatus (Nikon Micro Flex UFX-II), and can be known by analyzing a polarization photograph.

By the way, in the conventional method for producing a toner in which a binder resin, a charge control agent and a colorant are melt-kneaded, it is difficult to uniformly disperse the charge control agent as small dispersed particles, and it is possible to avoid considerable aggregation and dispersion. Did not. As a result, although the obtained developing toner showed high chargeability, the charge amount distribution was extremely wide and sufficient charge exchange property could not be secured.

In particular, a quaternary ammonium salt-type charge control agent and a metal complex salt-type charge control agent have poor dispersibility in a binder resin, and there has been no method for uniformly dispersing them as small dispersed particles in a toner. .

With respect to the quaternary ammonium salt-type charge control agent, the present inventors added a quaternary ammonium salt to a binder resin held at a temperature equal to or higher than its melting point, melt-kneaded, and added an additive such as a coloring agent to melt. After kneading, cooling and pulverizing and classifying,
A method of uniformly dispersing as small dispersed particles was proposed earlier. However, they have noticed that it is not possible to sufficiently secure the charging ability as described above using only small dispersed particles.

Therefore, in the present invention, a part of the dispersed particles is positively present as large agglomerated dispersed particles, so that a high charging ability is also secured. When a quaternary ammonium salt type charge control agent is used as the large dispersed particles, the quaternary ammonium salt is added to the binder resin held at a temperature equal to or higher than its melting point and melt-kneaded to reduce the small dispersed particles. While forming, large dispersed particles can be formed by adding a quaternary ammonium salt together with an additive such as a coloring agent and melt-kneading at a temperature lower than the melting point. Further, since the metal complex salt type charge control agent has a worse dispersibility than the quaternary ammonium salt, it can be added simultaneously with the quaternary ammonium salt by the above method. Therefore, the additive is preferably added to the melt-kneading step of the additive.

The toner for developing an electrostatic charge image obtained in this way has small dispersion particles uniformly dispersed as a charge control agent, and large dispersion particles exist in a part of the dispersion particles. Can be narrowed, the charge amount distribution can be narrowed, very stable chargeability can be secured, and the charge exchange property is excellent, so that charge decay occurs even when new toner is added. In addition, stable chargeability can be ensured for a long period of time, and fog and in-machine contamination can be suppressed even in continuous copying. Further, even when the environment changes such as temperature and humidity, the deterioration of the charge control function is small, so that the developing operation can be stably performed.

The quaternary ammonium salt type charge control agent used in the present invention is represented by the compounds represented by the following general formulas (I), (II) and (III), but the present invention is not limited thereto. Not something.

Specific examples of the compound represented by the formula (I) used in the present invention are shown below.

Further, specific examples of the compound represented by the general formula (II) used in the present invention are shown below.

Further, specific examples of the compound represented by the general formula (III) used in the present invention are shown below.

Furthermore, compounds other than the above-mentioned general formulas that can be used in the present invention are exemplified.

The mixing ratio of the quaternary ammonium salt is not particularly limited, but it is preferable to add the quaternary ammonium salt in a ratio of 0.1 to 3.0 parts by weight based on 100 parts by weight of the binder resin.

(A) Manganese complex of 2-hydroxy-1-naphthaldehyde (B) Cobalt complex of 2-hydroxy-1-naphthaldehyde (C) Maltol (D) Cobalt complex of aromatol (E) Cobalt complex of 2-aminocyclohexanone oxime (F) Iron complex of 8-quinolinol (G) Cobalt complex of 8-quinolinol Is not limited to these.

Examples of the binder resin used in the developing toner of the present invention include styrenes such as styrene, chlorostyrene, and vinylstyrene; monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl acetate, vinyl propionate, and vinyl benzoate. , Vinyl esters such as vinyl butyrate; methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate,
Esters of α-methylene aliphatic monocarboxylic acids such as phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate;
Examples thereof include vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl butyl ether; homopolymers and copolymers such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone; Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer , Polyethylene and polypropylene. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin, and wax can be used.

The binder resin used for the developing toner of the present invention is not limited to the above-mentioned resins, and any resin can be used as long as it meets the object of the present invention.

Further, as a coloring agent that can be used in the developing toner of the present invention, carbon black, an phosphorus blue,
Calcoil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal and the like can be exemplified as typical examples.

Further, various additives such as a cleaning aid, a fluidity promoter, and a magnetic material can be added as needed.

The toner for developing an electrostatic image according to the present invention can be applied to a magnetic toner containing a magnetic material or a capsule toner. The average particle size of the toner is about 30 μm or less, preferably 3 to 20 μm.

(Examples) Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these embodiments.

Example 1 Styrene-butyl acrylate copolymer (80/20) 100
Parts by weight were kept at 180 ° C., and the exemplified compound IV-2 was contained therein.
(Mp 110 ° C.), 1 part by weight was added, and the mixture was sufficiently stirred and mixed for several hours to obtain a treated binder resin. 100 parts by weight of this binder resin is carbon black (Legal made by Cabot Corporation)
330) 10 parts by weight, 5 parts by weight of a low molecular weight polypropylene (Viscol 660P manufactured by Sanyo Chemical Co., Ltd.) and the above exemplified compound IV-
2 and add the slab temperature with a Banbury mixer.
The mixture was melt-kneaded while being adjusted to 100 ° C. or lower, cooled, finely pulverized by a jet mill, and further classified by a classifier to obtain a toner having an average particle diameter of 11 μm.

On the other hand, the carrier was obtained by melt-kneading a styrene-butyl acrylate copolymer and magnetite powder at a mixing ratio of 30/70, pulverizing and classifying.

90 parts by weight of this carrier and 10 parts by weight of the toner were mixed to prepare a developing composition.

Example 2 Exemplified compound IV in place of Exemplified compound IV-2 of Example 1
-1 (mp 90 ° C.) was added in the previous step to give Exemplified Compound I-9
Example 1 except that (mp 175 ° C.) was added at a later stage.
A toner was obtained under the same conditions as described above, and mixed with the same carrier to prepare a developer composition.

Example 3 Exemplified compound II-2 (mp 80 ° C.) was used in place of Exemplified compound IV-2 in the former part of Example 1, and Example 1 was used in the latter part.
Example 1 except for using the same exemplary compound IV-2 as
A toner was obtained under the same conditions as described above, and mixed with the same carrier to prepare a developer composition.

Example 4 Except that Exemplified Compound I-2 (mp 115 ° C.) was used instead of Exemplified Compound IV-2 in the first part of Example 1, and Exemplified Compound A which is a metal complex type charge control agent was used in the second part, A toner was obtained under the same conditions as in Example 1, and mixed with the same carrier to prepare a developer composition.

Example 5 Except that Exemplified Compound IV-1 (mp 90 ° C.) was used instead of Exemplified Compound IV-2 in the first stage of Example 1, and Exemplified Compound C which is a metal complex salt type charge control agent was used in the second stage,
A toner was obtained under the same conditions as in Example 1, and mixed with the same carrier to prepare a developer composition.

Example 6 Except that Exemplified Compound II-1 (mp 85 ° C.) was used instead of Exemplified Compound IV-2 in the former part of Example 1, and Exemplified Compound E which is a metal complex type charge control agent was used in the latter part,
A toner was obtained under the same conditions as in Example 1, and mixed with the same carrier to prepare a developer composition.

Comparative Example 1 Styrene-butyl acrylate copolymer (80/20) 100
10 parts by weight of carbon black (Regal 330 manufactured by Cabot), 5 parts by weight of low molecular weight polypropylene (Viscol 660P manufactured by Sanyo Chemical), and Exemplified Compound I-9 based on parts by weight.
(Mp 170 ° C) 2 parts by weight were added, melt-kneaded while adjusting the slab temperature to 100 ° C or less with a Banbury mixer, cooled, then finely pulverized by a jet mill, and further classified by a classifier to obtain an average particle size. A toner having a diameter of 11 μm was obtained.
The same carrier as in Example 1 was used, and a developer composition was prepared in the same manner.

Comparative Example 2 Exemplified compound IV in place of Exemplified compound I-9 of Comparative example 1
Using -2 (mp 110 ° C), a toner was obtained under the same conditions and mixed with the same carrier to prepare a developer composition.

Comparative Example 3 Exemplified compound I in place of Exemplified compound I-9 of Comparative example 1
Using -2 (mp 115 ° C.), a toner was obtained under the same conditions and mixed with the same carrier to prepare a developer composition.

Comparative Example 4 A toner was obtained under the same conditions by using Exemplified Compound E which is a metal complex salt type charge control agent instead of Exemplified Compound I-9 of Comparative Example 1, and mixed with the same carrier to form a developer composition. Was prepared.

Comparative Example 5 Styrene-butyl acrylate copolymer (80/20) 100
Weight part was kept at 180 ° C., and the exemplified compound II-1 was added therein.
(Mp 85 ° C.) 2 parts by weight were added, and the mixture was sufficiently stirred and mixed for several hours to obtain a treated binder resin. 100 parts by weight of this binder resin is carbon black (Legal 33 manufactured by Cabot Corporation)
0) 10 parts by weight and 5 parts by weight of low-molecular-weight polypropylene (Viscol 660P manufactured by Sanyo Chemical Co., Ltd.) were added, melt-kneaded while adjusting the slab temperature to 100 ° C or less by a Banbury mixer, cooled, and then finely pulverized by a jet mill. Was carried out, and then classified by a classifier to obtain a toner having an average particle diameter of 11 μm. The same carrier as in Example 1 was used, and a developer composition was prepared in the same manner.

The evaluation results of each example and comparative example are shown in the following table.
As is clear from this table, in the example, the charge control agent having a large dispersion diameter of 0.5 μm or more was partially present for the charge control agent of a small dispersion diameter It can be seen that both the charge amount at the initial stage of blending and the charge amount after copying are improved as compared with Comparative Example 5 having only the charge control agent having a dispersion diameter. Comparative Examples 1 to 4 having only a charge control agent having a substantially large dispersion diameter
Sample No. 4 shows that the amount of charge when left for 12 hours after copying 10,000 sheets and the amount of charge under high temperature and high humidity are significantly reduced as compared with the example. As a result, it can be seen that the charge amount of the developing toner obtained in the example is superior in stability over time and environmental stability as compared with the initial stage of blending, and that the life of the developer is greatly extended.

(Effects of the Invention) According to the present invention, by employing the above-described structure, a charge control agent such as a quaternary ammonium salt type can be uniformly dispersed in a developing toner with a small dispersion diameter. The presence of a charge control agent having a large dispersion diameter, the charge amount distribution can be narrowed, very stable, and a high charge amount and excellent charge exchange property can be imparted. It has become possible to produce a developing toner having excellent properties.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahito Shinoki 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside the Fujimatsu Rocks Co., Ltd. In-house (56) References JP-A-60-118851 (JP, A) JP-A-63-202759 (JP, A)

Claims (2)

(57) [Claims] 1. An electrostatic image developing toner containing a binder resin, a colorant and a charge control agent, wherein 78 to 95% of the charge control agent particles dispersed in the toner have a small dispersion diameter of 0.3 μm or less. Characterized in that 5 to 20% of the toner has a large dispersion diameter of 0.5 μm or more. 2. Among the charge control agents, a quaternary ammonium salt type charge control agent is used as small dispersed particles, and a quaternary ammonium salt type charge control agent or a metal complex salt type charge control agent is used as large dispersed particles. The toner for developing electrostatic images according to claim 1, wherein the toner is used.