JP2876877B2 - Toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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.

[0002]

2. Description of the Related Art In the developing step, a developer used in an electrophotographic method such as an electrophotographic copying machine is once adhered to an image carrier such as a photoconductor on which an electrostatic image is formed. A method in which a toner image is transferred from a photoreceptor to transfer paper in a transfer process and then fixed on a copy paper surface in a fixing process is well known and widely used. At that time, as a developer for developing an electrostatic charge image formed on the latent image holding surface, a two-component developer composed of a carrier and a toner and a one-component developer (magnetic toner or Non-magnetic toner) is known. The toner contained in these developers is usually colored fine particles mainly composed of a resin, a colorant and the like. The toner includes a positively charged toner and a negatively charged toner. Conventionally, a known charge control agent, a coating agent for imparting desired chargeability to a carrier, and the like have been known as ones that impart positive or negative chargeability to the toner. As a method for producing toner particles, a method is known in which components such as a binder resin and a colorant are mixed in an appropriate amount, mixed, kneaded in a kneader or the like, cooled, then ground and classified.

[0003]

Generally, powdery dyes and pigments are generally used as the colorant, but the colorant flies a lot during the handling of raw materials in the toner manufacturing process.
There has been a problem with the worker's body and environmental pollution around the workplace. In order to cope with such a problem, there has been proposed a method of performing a pre-dispersion process by pre-kneading a resin and a colorant, that is, a so-called master batch process, etc. In addition, they have not been sufficiently satisfactory due to the complexity of the production process (reduction of production efficiency) and the like.

[0004] That is, an object of the present invention is to provide a toner using a colorant capable of reducing the contamination of the working environment during the production of the toner and facilitating the handling operation during storage and transportation. It is in. Another object of the present invention is to provide a toner in which a resin and other internal additives and a colorant are dispersed at a high and stable level. Concentration is obtained,
An object of the present invention is to provide a toner which is less fogged and does not easily cause a toner scattering phenomenon.

[0005]

Means for Solving the Problems The object of the present invention is to use a granulated colorant as a result of extensive studies by the present inventors, and to further improve the bulk density ratio when granulated. It has been found that this can be achieved by using a granulated colorant tuned to the above. That is, when the present invention is less
The bulk density ratio after the resin and before granulation and granulation 1.2 to 2.0
There is provided a granulated toner for developing electrostatic images, wherein the this you containing a coloring agent is.

Further, the present invention provides a toner for developing an electrostatic image, wherein the above-mentioned granulated colorant is adjusted by a compression granulation method. Hereinafter, the present invention will be described in detail. As the resin component usable in the present invention, various known resin components suitable for a toner for developing an electrostatic image can be used.

For example, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-acetic acid Vinyl copolymer, styrene-maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene -Octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic acid) Butyl copolymer and styrene-meta Styrene resins such as phenyl acrylate copolymer), styrene-α-methyl methyl acrylate copolymer and styrene-acrylonitrile-acrylate copolymer (a homopolymer or copolymer containing styrene or a styrene substituent) ), Vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, epoxy resin,
Polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin,
There are silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, and the like. Particularly preferred resins for use in the present invention are styrene resins, saturated or unsaturated polyester resins, and epoxy resins. Can be mentioned. In addition, the above resins are not limited to being used alone, and two or more resins can be used in combination.

Further, the above resin is composed of a low molecular weight component and a high molecular weight component described in, for example, JP-B-55-6895 and JP-B-63-32180 in consideration of fixing performance and developer durability. Resin having at least two molecular weight peaks, or JP-B-51-2335
4. A partially crosslinked resin described in JP-A-50-44836 may be used. As for the glass transition temperature of the resin, the transition start temperature (inflection point) when measured by a differential thermal analyzer or a differential scanning calorimeter is preferably 50 ° C. or more. When the glass transition temperature is lower than 50 ° C., when the toner is left at a high temperature of 40 ° C. or higher for a long period of time, the toner aggregates or adheres to the toner, causing a problem in use.

The raw material of the granulated colorant used in the present invention is not particularly limited as long as it is a usual powdery colorant. A method for granulating a powdery colorant is described in, for example, JP-A-2-14285.
8. It is preferable to use a compression granulation method using a compression granulation apparatus such as a roll compression molding machine described in JP-A-3-193129 in order to obtain a desired bulk density ratio. The load for compressing the powdery colorant is such that the bulk density ratio before and after granulation is 1.2 to 2.0 in consideration of the bulk density of the raw material, the particle size, and the like.
Preferably, it is appropriately selected so as to be 1.2 to 1.8.

[0010] When the bulk density ratio is less than 1.2, a lot of flying occurs during the handling of the colorant, the bulk of the raw material is increased, the shear during kneading is hardly applied, the dispersibility in the toner is deteriorated, and the toner performance is deteriorated. Leads to deterioration. On the other hand, if the bulk density ratio is larger than 2.0, the handling properties of the colorant are good, but the cohesive strength of the colorant is excessively increased, so that sufficient dispersibility cannot be obtained during kneading, resulting in poor toner performance. In addition, the stability of image density, the stability of fogging, and the state of toner scattering during continuous copying / printing of toner can be significantly improved by using a granulating colorant. As the colorant, any suitable pigment or dye is used.

[0011] For example, titanium oxide, zinc white, alumina white, calcium carbonate, navy blue, carbon black, lamp black, iron black, ultramarine, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine dyes and pigments, chrome yellow Any conventionally known dyes and pigments such as quinacridone, benzidine yellow, rose bengal, triallylmethane dyes, anthraquinone dyes, monoazo and disazo dyes can be used alone or in combination. These colorants are preferably 0.5 to 100 parts by weight of the binder resin.
20 parts by weight, more preferably 2 to 10 parts by weight.

The bulk density of the colorant was measured according to the apparent specific gravity measurement method described in JIS K6221. For the purpose of adjusting the chargeability of the toner, in the case of a positively chargeable toner, a known charge control agent such as a nigrosine dye, a quaternary ammonium salt, a triaminotriphenylmethane compound, an imidazole compound, or the like, In this case, an appropriate amount of a known charge control agent such as a metal-containing azo dye, a metal salicylate compound and a metal alkylsalicylate compound may be added. The addition amount is preferably 0.05 to 10 parts by weight based on 100 parts of the resin.

[0013] In addition, auxiliary agents such as various plasticizers and release agents can be added to the toner for the purpose of adjusting thermal characteristics, physical characteristics, and the like. The addition amount is preferably 0.1 to 10 parts by weight based on 100 parts of the resin. Further, by adding a fine powder of titania, alumina, silica, or the like to the toner particles and coating the toner particles with the fine powder, the fluidity and aggregation resistance of the toner can be improved. The addition amount is preferably 0.05 to 5 parts by weight based on 100 parts by weight of the toner particles.

When the toner of the present invention is used in a two-component developer, it may be mixed with a magnetic carrier, and the content ratio of the carrier and the toner in the developer is 100:
1 to 10 parts by weight is preferred. As a magnetic carrier,
Conventionally known materials such as iron powder, ferrite powder, magnetite powder, and magnetic resin carrier having a particle size of about 30 to 200 μm can be used. Further, those whose surfaces are coated with a known silicone-based resin, acrylic-based resin, fluorine-based resin, or the like, or a mixture of these resins can also be suitably used.

Further, the toner of the present invention may be used as a magnetic one-component toner containing a magnetic substance such as magnetite or a non-magnetic one-component toner containing no magnetic substance, which is a one-component developer not using a carrier. Can be.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the scope of the invention. In the following examples, “parts” simply means “parts by weight”.

<Example 1>

[Table 1] 100 parts of copolymer resin having a styrene / n-butyl acrylate = 82/18 monomer weight ratio (flow softening point 130 ° C., glass transition point 62 ° C.) Colorant carbon black MA7F 5 parts (Mitsubishi Kasei・ Granulation type, bulk density ratio = 1.36 ・ Charging control agent Bontron P51 2 parts (Orient Chemical Co., Ltd. quaternary ammonium salt) ・ Low molecular weight polypropylene Biscol 550P 2 parts (Sanyo Chemical Co., Ltd. )

And kneading using a continuous twin screw extruder.
It was pulverized and classified to obtain a black toner having an average particle size of 10 μm. To 100 parts of this black toner, 0.2 parts of silica powder (R972 manufactured by Nippon Aerosil Co., Ltd.) was externally added using a Henschel mixer to obtain Toner A. Ferrite powder carrier 100 having an average particle diameter of 100 μm and surface-coated with 4 parts of the obtained toner A and a methyl silicone-containing resin
The parts were mixed and stirred to prepare a developer.

Next, this developer was used at 40 ° C./85-90% RH using a copying machine using an organic photoconductor as a photosensitive member.
Under the high temperature / high humidity conditions of 100,000 actual printing tests were performed. The replenishment toner used in the actual test was
Toner A having the same composition as the toner used in the developer
It is. As a result of the actual test, even in the actual image after 100,000 copies, the uniformity and density of the black portion of the copy were high and stable, and there was almost no increase in fog, which is a stain on the white portion of the copy, and the toner scattered in the machine. Thus, the toner and the developer were excellent in durability even under a severe environment of high temperature and high humidity. When the degree of dispersion of the carbon black in the black toner A was observed with an optical microscope, good dispersion was confirmed.

<Embodiment 2>

[Table 2] 100 parts of a copolymer resin having a styrene / n-butyl acrylate = 82/18 monomer weight ratio-100 parts of colorant copper phthalocyanine blue granulated product (bulk density ratio = 1.50)-Charge control agent Bontron P512 Parts (quaternary ammonium salt manufactured by Orient Chemical Co., Ltd.) and low molecular weight polypropylene biscol 550P (manufactured by Sanyo Chemical Co., Ltd.) except that the toner and the developer were prepared in the same manner as in Example 1, Table 1 shows the results of the actual photograph test of 000 sheets.

<Comparative Example 1> Powdered carbon black (MA7P, bulk density 0.22 g) before granulation was prepared using the colorant of Example 1
/ M ³ ), except that the toner and the developer were prepared in the same manner as in Example 1, and a 100,000-sheet actual test was performed.

<Comparative Example 2> The colorant of Example 2 was mixed with a powdery copper phthalocyanine bull before granulation (having a bulk density of 0.20 g /
Except for changing to m ³ ), a toner and a developer were prepared in the same manner as in Example 2, and the results of a 100,000-sheet actual test were shown in Table 1.

[0023]

[Table 3]

(Note) The coloring agents of Examples 1 and 2 were granulated by a roll compression molding machine.

[0025]

By using the toner for developing an electrostatic image of the present invention, the working environment during the production of the toner is remarkably improved, and the dispersibility of the colorant in the toner is not deteriorated. Also, regardless of the conditions of the use environment, the change in the copy image density is small even during continuous copying, the fog is stable, and the toner scattering state is excellent. To provide.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-142858 (JP, A) JP-A-2-291568 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/08

Claims (2)

(57) [Claims] Claims 1. At least a resin and before and after granulation
A toner for developing electrostatic images , comprising a granulated colorant having a bulk density ratio of 1.2 to 2.0 . 2. The method according to claim 1, wherein the granulating colorant is prepared by a compression granulation method.
2. The colorant according to claim 1, wherein the colorant is a regulated colorant.
An electrostatic image developing toner.