JPH0762766B2 - Toner for electrostatic image development - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrostatic charge image developing toner, and more particularly to an electrostatic charge image developing toner containing a specific compound as a charge control agent (polarity control agent).

BACKGROUND ART As means for developing an electrostatic latent image formed on an electrophotographic photoreceptor or electrostatic recording body, a method using a liquid developer (wet developing method) and a colorant in a binder resin are used. A method in which a dispersed toner or a one-component or two-component dry developer in which the toner is mixed with a solid carrier is used (dry development method) is generally adopted. Although each of these methods has advantages and disadvantages, the dry development method is widely used at present.

By the way, in the toner (development powder), a desired chargeability cannot be obtained by simply dispersing a colorant such as a dye or a pigment in a binder resin, and therefore, a charge control agent (polarity control agent) Is usually added in an appropriate amount. Typical examples of conventional charge control agents include (i) a nigrosine dye that gives a positive charge to the toner, and (ii) a chromium-containing monoazo complex or a chromium-containing salicylic acid compound that gives a negative charge to the toner. Examples thereof include metal-containing dyes such as complexes and chloro-containing organic dyes (copper phthalocyanine green, chloro-containing monoazo dyes). However, such conventional charge control agents are substances that do not have good charge controllability over a long period of time because they are mostly colored substances, have poor compatibility or wettability with the binder resin, or are sublimable. Therefore, it is not suitable for color electrophotographic toner.

In addition, although the toner containing such a conventional charge control agent shows good developing characteristics at the initial stage, it has shortcomings such as a short life and poor environmental stability (stability to temperature and humidity changes). Regarding these conventional colorants and charge control agents, Japanese Patent Publication Nos. 48-25941 and 48
-26784, JP-B-49-20225, JP-A-50-140137, JP-A-50-142037, JP-A-50-142038, JP-B-46-43440
Issue, Japanese Patent Publication No. 48-30899, Japanese Patent Publication No. 49-46423, Japanese Patent Publication No. 49-2
No. 6909, JP-A-49-51949 and JP-A-49-134303.

However, it is necessary to use chlorinated paraffin, unsaturated polyester, etc. as a binder resin to control the toner to be negatively charged, and to use a specific polyester resin having a kind of cross-linking structure from the beginning (non-linear low melting point aromatic It is known to use (such as a reaction product of a group resin and a salicylic acid chelate), but it is difficult to obtain a desired molecular weight as a binder with these resins, and therefore, important thermal properties (at the time of fixing) as a toner are not obtained. It was recognized that there was a problem in that it was not possible to obtain (melting characteristics with a heat roll), a copy discharge error due to copy wrapping around the heat roller, and an offset phenomenon in which the toner image on the paper moved to the roller surface and the letters became unclear, .

Object The first object of the present invention is to provide a toner in a one-component or two-component dry developer in which a colorless polarity control agent is contained so that the charge is negatively controlled for a long period of time without impairing the original color of the color material. Is provided. A second object of the present invention is to provide a toner for developing an electrostatic charge image, which is suitable for high-speed development as well as being capable of always obtaining a stable image and which is excellent in durability and environmental stability. A third object of the present invention is to provide a dry toner which does not cause the offset phenomenon.

Structure The toner for developing an electrostatic image of the present invention comprises at least one metal salt of salicylic acid and a metal salt of a salicylic acid derivative.
The feature is that the seed is contained as a charge control agent.

By the way, the inventors of the present invention have conducted various studies and studies on charge control of dry toner, and found that metal salts of salicylic acid (particularly zinc salts) and metal salts of salicylic acid derivatives (particularly zinc salts) are extremely effective as charge control agents. I confirmed. The present invention has been made based on such findings.

The metal salt of salicylic acid or a salicylic acid derivative used as a charge control agent in the present invention can be represented by the following general formula.

(However, R ¹ , R ² and R ³ are hydrogen or an alkyl group having 1 to 10 carbon atoms or an allyl group, but particularly hydrogen or 1 to 6 carbon atoms.
Alkyl group or allyl group is preferred. Where R ¹ , R ²
And R ³ may be the same or different at the same time.
Further, Me is any metal selected from zinc, nickel, cobalt, lead and chromium, but zinc is particularly desirable. ) Such metal salts represented by the general formula are CLARK, JLKao, H.
(1948) J. Amer. Chem. Soc. 70, 2151 can be easily synthesized by the method described. For example, 2 mol of salicylic acid sodium salt (including sodium salt of salicylic acid derivative) and 1 mol of zinc chloride are added to a solvent, mixed, heated and stirred to obtain a zinc salt. This metal salt is a white-colored crystal,
It does not show coloring even when dispersed in a toner binder. Metal salts other than zinc salts can also be produced according to the above method. These metal salts may be used alone or in combination of two or more kinds. The toner of the present invention contains a colorant and a binder resin as essential components together with these compounds.

The colorants used in the present invention are conventionally magenta, cyan,
All those which have been used as colorants for color toners such as yellow can be applied. Specifically, inorganic pigments such as ultramarine blue, dark blue, silica, alumina, and titanium; azo dyes and pigments, anthraquinone dyes and pigments, phthalocyanine dyes and pigments, quinacdrine dyes and pigments, perylene dyes and pigments,
Organic dyes and pigments such as indigo dyes and pigments, basic dyes and lake salts thereof can be exemplified, and carbon black may also be used in the present invention, if necessary. These colorants may be used as a mixture of two or more kinds. Among these, it is preferable to use quinacridone (for magenta toner), copper phthalocyanine (for cyan toner), and benzidine yellow (for yellow toner).

Further, as the binder resin used in the present invention, as well as the above-mentioned colorant, all the binder resins used so far as the binder resin for toner can be applied. Specifically, styrene such as polystyrene, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-butadiene copolymer Including resin, saturated polyester resin, unsaturated polyester resin, epoxy resin, phenol resin, maleic acid resin, chroman resin,
Chlorinated paraffin, xylene resin, vinyl chloride resin,
Examples include polypropylene and polyethylene. It goes without saying that two or more kinds of these binder resins may be appropriately mixed and used. Of these, use of polystyrene, styrene resin, and epoxy resin is advantageous.

In the toner of the present invention, in addition to the above components, various plasticizers (dibutyl phthalate, dioctyl phthalate, etc.) and resistance adjusters (for adjusting the thermal properties, electrical properties, and physical properties of the toner as necessary) It is also possible to add auxiliaries such as tin oxide, lead oxide, antimony oxide).

The amount of the metal salt in the toner is 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight, based on 100 parts by weight of the binder resin. In addition, the amount of colorant in the toner depends on the binder resin
The amount is 0.5 to 10 parts by weight, preferably 1 to 7 parts by weight, based on 100 parts by weight.

Further, in the present invention, after the production of toner particles (5 to 20 μm), fine powder such as TiO ₂ , Al ₂ O ₃ and SiO ₂ is added to the toner particles and the surface of the toner particles is coated with these to improve the fluidity of the toner. It is also effective to improve the properties of the photoconductor and to prevent deterioration of the photoconductor by adding zinc stearate, phthalic acid and the like.

As described above, the toner of the present invention can be used as a touch-down type one-component developer or can be used as a normal one-component toner by adding and dispersing a magnetic substance (magnetite powder or the like). Further, it can be mixed with a carrier and used as a two-component developer.

As a carrier, a styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, acrylic acid ester is formed on the surface of a core material (iron powder, nickel powder, ferrite powder, glass beads, etc.) having a particle size of about 50 to 300 μm. A polymer, a methacrylic acid ester polymer, a silicone resin, a polyamide resin, an ionomer resin, a polyphenylene sulfide resin, or the like, or a mixture of these resins is used. In particular, like the toners of the present invention, certain metal salts therein (zinc salicylate salt,
When a compound such as a zinc salt of a salicylic acid derivative) is added, a desired more stable negative charge is given to the metal salt, and therefore, as a resin for coating the carrier, a silicone resin or a silicone resin is used. It is advantageous to use a dispersion of electrically conductive fine powder.

It is known that a metal complex of salicylic acid or salicylic acid is used as a charge control agent (Japanese Patent Laid-Open No. 55-42752), but in this case, the extent to which the present inventors intend, as will be seen below. Is not effective.

Next, examples and comparative examples will be shown. All parts here are parts by weight.

Example 1 Styrene-n-butylmethacrylate copolymer 100 parts Copper phthalocyanine bleu (Toyo Ink Co., Rionogenble-KL) 5 parts 3,5-di-tertiary-butylsalicylic acid zinc salt 3 parts Melt kneaded with a hot roll mill, After cooling, coarse pulverization was performed using a hammer mill, and fine pulverization was performed using an air jet type fine pulverizer. The obtained fine powder was classified to a particle size of 5 to 20 μm to prepare a blue toner according to the present invention. This toner 3.
Two parts of a dry developer was prepared by mixing 5 parts of carrier and 100 parts of carrier (spherical ferrite powder having a particle size of about 100 μm and having a silicone resin coating layer having a film thickness of 1 μm). The charge amount by the blow-off method was measured as -18 μc / g.

When this developer was used for development with a dry electronic copying machine (Ricoh FT5050, manufactured by Ricoh Co., Ltd.) at 10 ° C. 15% RH and 20 ° C. 60% RH, a clear blue toner image without fog was obtained. In addition, the copy quality did not deteriorate even after continuous copying of 50,000 sheets. Furthermore, in the environment of 30 ℃ and 90% RH
After copying 10,000 copies continuously, the image quality did not change and good quality was maintained. It was found that when a chromium salt was used instead of the zinc salt, good results were obtained although the chromium salt was slightly inferior to the zinc salt.

Comparative Example 1 A comparative toner was prepared in the same manner as in Example 1 except that the following toner components were used to prepare a two-component dry developer.

Styrene-2 hexyl ethyl acrylate-n butyl methacrylate copolymer 100 parts Copper phthalocyanine blue- (Lionogen Blue KL manufactured by Toyo Ink Co., Ltd.) 5 parts Chromium-containing monoazo complex 0.5 parts The charge amount of this comparative developer by the blow-off method is- 7 μc /
It was measured as g.

Subsequently, when this comparative developer was developed in the same manner as in Example 1, a copy having a dark blue color tone was obtained. Also,
After continuous copying of 5,000 sheets, the charge amount was less than -5 μc / g by the developer blow-off method, resulting in a smeared and unclear image on the background.

Comparative Example 2 A slightly greenish blue toner was prepared in exactly the same manner as in Example 1 except that the toner components were changed to those described below.
A two-component dry developer was created.

Styrene-n-butyl methacrylate copolymer 100 parts Copper phthalocyanine blue (Toyo Ink Co., Ltd. Rionogenble-KL) 5 parts 3,5-di-sha-butyl-sulfate chromium complex compound
0.5 part The charge amount of this comparative developer by the blow-off method is -13 μc /
It was measured as g.

Subsequently, when this comparative developer was developed in the same manner as in Example 1, a blue copy with a slight turbidity was obtained.
In addition, after continuous copying of 5000 sheets, the charge amount of the developer by the blow-off method decreased to -6 μc / g, and an unclear image with a soiled background was obtained. Further, when continuously copied in an environment of 30 ° C. and 90% RH, the charge amount decreased to -3 μc / g, and the background part became more dirty.

Example 2 The pigment of Example 1 is used as a yellow dye (Neozapon Yellow 073).
A toner according to the present invention was prepared and a two-component dry developer was prepared in the same manner as in Example 1 except that the above was used. The charge amount by the blow-off method was -20 μc / g.

Subsequently, this developer was developed in the same manner as in Example 1 to obtain a fog-free yellow toner image. In addition, no reduction in copy quality was observed even after continuous copying of 10,000 sheets.

Example 3 A two-component dry developer was prepared by preparing a red toner having a particle size of 5 to 20 μm according to the present invention in exactly the same manner as in Example 1 except that the toner components were changed to those described below. The charge amount by the blow-off method was -21 μc / g.

Styrene-n-butyl methacrylate copolymer 100 parts 3,5-di-tertiary-butylsalicylic acid zinc salt (Bontron E-84 manufactured by Orient Chemical Co., Ltd.) 3 parts Naphthol red FGR (manufactured by Hoechst) 5 parts Using this developer, Ricoh Company 60 with an electronic copier (FT4060)
After continuous copying of 000 sheets, stable and good red copies were obtained even after 60,000 sheets.

Example 4 A green toner having a particle size of 5 to 20 μm according to the present invention was produced in the same manner as in Example 1 except that the toner components were changed to those described below to prepare a two-component dry developer. The charge amount by the blow-off method was -15 μc / g.

Styrene-n-butylmethacrylate copolymer 100 parts 3,5-ditertiary-butylsalicylic acid zinc salt (Bontron E-84 manufactured by Orient Chemical Co., Ltd.) 3 parts Copper phthalene anine blue (Rionogen Blue MG5 manufactured by Toyo Ink Co., Ltd.) 2 Part Rionol Yellow FGN-T (manufactured by Toyo Ink Co., Ltd.) 5 parts Using this developer, 60 with Ricoh's electronic copying machine (FT4060)
After continuous copying of 000 sheets, stable and good green copies were obtained even after 60,000 sheets.

Example 5 A toner having a particle size of 5 to 20 μm according to the present invention was prepared in the same manner as in Example 1 except that the toner components were changed to those described below to prepare a two-component dry developer. The charge amount by the blow-off method was -20 μc / g.

Styrene-n-butyl methacrylate copolymer 100 parts Polypropylene (Viscole 330P manufactured by Sanyo Kasei Co., Ltd.) 4 parts Carbon black 13 parts 3,5-di-tert-butyl-salicylic acid zinc salt 2 parts This developer was used in the same manner as in Example 1. After development, a black toner image free from fog was obtained. Also, 20000
No deterioration in copy quality was observed even after continuous copying of one sheet.

An image was printed using this toner on an electrophotographic copying machine (Ricoh's reversal developing machine, Myricopy M5) that adopted the touchdown development method, and the toner charge amount on the developing sleeve was -15 μc / g. Thus, a clear black image without fog was obtained. No deterioration in copy quality was observed even after continuous copying of 20000 sheets. The value of the amount of charge of the toner here is obtained from the amount of charge flowing when sucked from the developing sleeve and the weight of the sucked toner.

Example 6 A toner having a particle size of 5 to 15 μm was produced in the same manner as in Example 1 except that the toner components were changed to those described below.

Styrene-n-butylmethacrylate copolymer 50 parts Fe ₃ O ₄ (EPT500 manufactured by Toda Kogyo Co., Ltd.) 50 parts 3,5-di-tert-butyl-salicylic acid zinc salt 2 parts Electron using touch-down development method with this toner Photocopying machine (Ricoh's reversal developing machine, Myricopy M1
When an image was printed at 0), the amount of charge of the toner on the developing sleeve was −10 μc / g, and a clear black image without fog was obtained. No deterioration in copy quality was observed even after continuous copying of 20000 sheets.

Comparative Example 3 A toner having a particle size of 5 to 20 μm was prepared in the same manner as in Example 6 except that the toner components were changed to those described below.

Styrene -n-butyl methacrylate copolymer 50 parts BL-250 (Titan Kogyo Co. Fe ₃ O ₄ magnetite) 50 parts Bontron S-34 (Orient Chemical Co. containing chromium complex)
2 parts This toner was used to form an image on an electrophotographic copying machine (Milicopy M10 manufactured by Ricoh Co., Ltd.), and a clear black image was obtained at an initial charge amount of −15 μc / g on the developing sleeve. However, when 5000 sheets were continuously copied, the charge amount of the toner on the developing sleeve decreased to -4 μc / g, and an unclear image with a dirty background was formed.

Example 7 The toner component was the following saturated polyester resin 50 parts Polypropylene (Viscole 330 manufactured by Sanyo Kasei Co., Ltd.) 3 parts Fe ₃ O ₄ (black magnetic material EPT500 manufactured by Toda Kogyo Co., Ltd.) 30 parts 3,5-di-sali-butyl salicylate zinc The particle size was 5 to 20 in the same manner as in Example 1 except that 2 parts of salt was used.
When a toner having a size of μm was prepared and an image was formed using a reversal developing machine (Mylicopy M10, manufactured by Ricoh Co., Ltd.), the toner charge amount on the developing sleeve was −13 μc / g, and a clear image without fog was obtained. In addition, no reduction in copy quality was observed even after continuous copying of 20,000 sheets.

Effect As is clear from the description of the examples, the toner of the present invention containing a specific metal salt (particularly a zinc salt of salicylic acid or a salicylic acid derivative) as a polarity control agent is hardly affected by temperature and humidity, and a large number of sheets are added. It is also effective in obtaining a copy.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masami Tomita, 1-3-3 Nakamagome, Ota-ku, Tokyo Tokyo Ricoh Co., Ltd. (72) Inventor, Hachiro Tosaka, 1-3-6 Nakamagome, Ota-ku, Tokyo Stocks In Ricoh Company (72) Inventor Toshiki Minatani 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Moto Hajime 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Company ( 56) References JP-A-53-127726 (JP, A) JP-A-56-6247 (JP, A) JP-A-57-101853 (JP, A) JP-A-58-1158 (JP, A)

Claims (1)

[Claims] 1. A toner for developing an electrostatic image, comprising at least one selected from the group consisting of salicylic acid metal salts and salicylic acid metal salts.