JPH05119509A - Positively chargeable developer for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To provide a positively chargeable toner having satisfactory anti- offsetting property and winding resistance, capable of fixing at a low temp. or at a high speed, ensuring satisfactory dispersibility of a releasing agent in binding resin, hardly causing toner filming and carrier contamination during development, capable of stably imparting satisfactory positive chargeability over a long period of time and forming a high quality image. CONSTITUTION:This developer consists of a toner and a carrier a silicone resin and the toner contains polyester resin as binding resin, wax having <=5 acid value such as deliberated fatty acid type carnauba wax as a releasing agent and a nigrosine dye, a quat. ammonium salt compd., ultramarine having <=27ml/100g oil absorption, a triphenylmethane dye or a polymer contg. amino groups as an electrostatic charge controlling agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry developer for developing an electrostatic charge image (electrical or magnetic latent image) formed in electrophotography, electrostatic printing or the like, and more specifically, In the heat roll fixing method, fixing is sufficiently performed at a lower temperature,
Further, the present invention relates to a positively chargeable developer that does not adversely affect the developer properties such as the charge properties even when used for a long time in the developing device.

[0002]

2. Description of the Related Art An electrostatic charge image formed by an electrophotographic method, an electrostatic printing method, an electrostatic recording method, etc., is generally dried by a dry toner containing a binder resin and a colorant as a main component in the dry method. , Is transferred and fixed on copy paper. Although there are various fixing methods for toner images, the heat roller fixing method is widely adopted because of its high thermal efficiency and high-speed fixing. When performing high-speed fixing by such a heat fixing method, the toner is required to have good low-temperature fixing property (or low fixing lower limit temperature), and therefore, a binder resin having a low softening point is required. used. However, when a low softening point resin is contained in the toner, a part of the toner image adheres to the surface of the heat roller at the time of fixing, and this is transferred onto copy paper to cause scumming, a so-called offset phenomenon or copy paper. Is attached to the surface of the heat roller and is wound around, which is a so-called wrapping phenomenon (especially when the temperature of the heat roller is low).

Therefore, as means for preventing these phenomena, Japanese Patent Application Laid-Open Nos. 51-143333 and 57-14875.
No. 2, No. 58-97056, No. 60-247250, etc., it is proposed to add solid silicone varnish, higher fatty acid, higher alcohol, various waxes and the like as a release agent. However, under the present circumstances, a release agent which exhibits sufficient offset resistance and wrapping resistance while maintaining good low-temperature fixability has not yet been found.

Specifically, conventional polyolefin waxes such as low molecular weight polyethylene and low molecular weight polypropylene have good offset resistance, but do not have sufficient low-temperature fixability, and carnauba wax, candelilla wax and the like. Although the vegetable wax has good offset resistance and low-temperature fixability, it does not have sufficient roll resistance, and solid silicone varnish, solid silicone oil, amide wax, higher fatty acid, and higher alcohol have low-temperature fixability. Is good, but the offset resistance and wrapping resistance are not sufficient. Moreover, since the conventional release agent has poor dispersibility in the binder resin, the release agent is often released from the toner and adheres to the photoconductor or the developing sleeve during development, so-called filming. Carrier pollution due to
It was difficult to form a high-quality image stably over a long period of time.

On the other hand, it is known to use a polyester resin as a binder resin in order to maintain the low temperature fixability. However, the polyester resin itself has a strong negative chargeability, and it is difficult to use the resin for a positively chargeable toner.

[0006]

That is, at the time of fixing, while exhibiting good low-temperature fixability, sufficient offset resistance and wrapping resistance are exhibited, and filming and carrier contamination do not occur at the time of development. At present, a toner or a developer capable of stably obtaining a high-quality image for a long period of time has not yet been found.

Therefore, an object of the present invention is to provide a positively chargeable developer for electrostatic image development which has sufficient offset resistance at the time of fixing, has a low fixing lower limit temperature, and does not wrap around a fixing roll. Especially. Furthermore, another object of the present invention is to obtain a high-fidelity image having the same fidelity as the initial image even in continuous use without causing scumming and toner scattering, and positive charging property for electrostatic image development suitable for high-speed fixing. To provide a developer.

[0008]

As a result of intensive studies, the present inventors have used a polyester resin as a binder resin, contain a specific release agent, and contain a specific charge control agent. It has been found that the above object can be achieved by the toner having the constitution, and the present invention has been completed.

That is, according to the present invention, in a developer comprising a carrier coated with a silicone resin and a toner mainly containing a binder resin, a release agent and a charge control agent, at least the binder of the toner is bound. A polyester resin as a resin, a free fatty acid type carnauba wax having an acid value of 5 or less, a montan ester wax and / or an oxidation rice wax having an acid value of 10 to 30 as a release agent, and a charge control agent. The present invention provides a positively chargeable developer for developing an electrostatic charge image, which comprises at least one of the compounds represented by the following (1) to (5). (1) Nigrosine dye. (2) Quaternary ammonium salt compound. (3) Ultramarine with an oil absorption of 27 ml / 100 g or less. (4) A triphenylmethane dye represented by the following general formula [II].

[Chemical 2] (5) An amino group-containing polymer represented by the following general formula [III].

[Chemical 3]

In the positively chargeable developer of the present invention, a polyester resin is used as a binder resin for the toner, and a free fatty acid type carnauba wax having an acid value of 5 or less, a montan ester wax and an oxidation agent of 10 to 30 are used as a releasing agent. At least one of the oxidized rice waxes described above is used, and at least one of the compounds represented by the above (1) to (5) is used as the charge control agent. Therefore, sufficient offset resistance and wrapping resistance at the time of fixing are achieved. In addition, the minimum fixing temperature is sufficiently low, and the dispersibility of the release agent in the binder resin is good, so there is little toner filming or carrier contamination during development, and a stable positive charge amount. Is obtained in the toner, quality abnormalities such as toner fogging on the background of the image are prevented, and stable high-quality images can be formed over a long period of time. The things.

In the dry two-component type developer, since the surface energy is low and the toner fusion to the surface can be extremely reduced, it is desired to use a carrier coated with a silicone resin. However, according to the research conducted by the present inventors, a charge control agent capable of imparting positive chargeability to a toner using a polyester resin binder, such as the toner used in the present invention, has been found to be extremely useful for this silicone resin-coated carrier. It became clear that the range was limited to. Therefore, in the toner used in the present invention,
As the charge control agent, the compounds represented by the above (1) to (5) are used. These charge control agents impart a charge amount of the toner to 10 to 30 μc / g by a blow-off method with respect to the carrier coated with the silicone resin used. Hereinafter, the charge control agent used in the present invention will be described in detail.

(Nigrosine Dye) Nigrosine is a bluish black to blackish dye obtained by oxidizing aniline and aniline hydrochloride with nitrobenzene at 160 to 180 ° C. in the presence of iron chloride. Its exact structure is unknown, but triphenazine oxazine, phenazine azine and small amounts of In
It is a mixture of duline 6B. The present inventors have found that the relationship between the charge amount of the toner and the pH of the nigrosine-based dye is shown in FIG.
I found that it would be like. FIG. 1 shows the case where the content of the nigrosine dye in the toner is 2% by weight. It is preferable to use a nigrosine-based dye having a pH of 8 or less because the charge amount is high and the charge stability is very high. The pH of the nigrosine dye is adjusted by acid treatment of nigrosine. Also, the method for measuring pH is JISK.
5101-24.

(Quaternary Ammonium Salt Compound) The quaternary ammonium salt compound can also impart a sufficient positive charge amount to the toner. As the quaternary ammonium salt compound, those represented by the following general formula [I] are particularly preferable.

[Chemical 1]

(Ultramarine) Ultramarine is a substance represented by sulfur-containing sodium aluminosilicate (Na ₆ Al ₆ Si ₆ O ₂₄ S ₄ ). The present inventors have found that the relationship between the toner charge amount and the ultramarine oil absorption amount is as shown in FIG.
FIG. 2 shows the case where the ultramarine content in the toner is 3% by weight.
Therefore, in the present invention, the oil absorption is 27 ml / 100.
Ultramarine of g or less is used.

The oil absorption is 1000 g of a dried sample of ultramarine.
Is placed on a slab with a smooth surface, a small amount of alkali-refined linseed oil placed in a 2 ml microburet is dripped little by little, and a pressure of about 100 g is applied to mix well with a 15 x 115 mm, 0.5 mm thick stainless steel spatula, Read the minimum amount of linseed oil in which the sample and linseed oil are molded into one spherical shape, and read the amount of linseed oil per 100 g of ultramarine (m
It is obtained by converting into l).

(Triphenylmethane Dye) The triphenylmethane dye represented by the following general formula [II] can also impart a sufficient amount of positive charge to the toner.

[Chemical 2]

Further, the triphenylmethane dye represented by the above general formula [II] may be laked before use. In this case, rake formation is carried out by a known method. That is, an aqueous solution of a raking agent such as phosphotungstic acid, phosphotungstic molybdic acid or oxalic acid is added to an acetic acid solution of a dye to precipitate a lake pigment, which is filtered, washed with water, dried and ground.

(Amino group-containing polymer) The following general formula [II
The amino group-containing polymer represented by I] can also provide a toner with a sufficient normal band amount.

[Chemical 3]

The amino group-containing polymer represented by the above general formula [III] is a styrene-containing polymer together with a polymerization initiator such as azobisisobutyronitrile in a heated polymerization solvent such as xylene under a nitrogen stream. A mixed solution of a monomer and a monomer containing an amino group is added dropwise for polymerization, the pressure is reduced, and the polymerization solvent and the residual monomer are removed.

With respect to the addition amount of these charge control agents, in the case of the above-mentioned nigrosine dye, quaternary ammonium salt compound, ultramarine blue and triphenylmethane dye, 0.5 to 15% by weight of the total toner, preferably 1 ~ 5% by weight. If it is less than this range, it is not possible to impart a sufficient positive charge amount to the toner. Conversely, if it is more than this range, the charge control agent desorbs from the surface of the toner during continuous use in the developing device, The charge amount may change significantly. Also,
In the case of the amino group-containing polymer, the total amount of the toner is 5 to 5.
It is 30% by weight, preferably 10 to 15% by weight. If it is less than this range, a sufficient amount of positive charge cannot be imparted to the toner, and conversely if it is more than that, the low temperature fixability may be insufficient.

The core particles of the carrier coated with the silicone resin used in the present invention may be those conventionally known, for example, ferromagnetic metals such as iron, cobalt and nickel; magnetite, hematite, ferrite and the like. Alloys and compounds; glass beads and the like. The average particle size of these core particles is usually 10 to 1000 μm, preferably 30 to 500 μm. The amount of the silicone resin used is usually 1 to 10% by weight based on the carrier core particles.

A conventionally known silicone resin is used as the silicone resin for coating the carrier core particles. For example, commercially available products include KR261, KR271, KR272, KR275, manufactured by Shin-Etsu Silicone Co., Ltd.
KR280, KR282, KR285, KR251, K
R155, KR220, KR201, KR204, KR
205, KR206, SA-4, ES1001, ES1
001N, ES1002T, KR3093 or SR2100, SR2101, SR210 manufactured by Toray Silicone Co., Ltd.
7, SR2110, SR2108, SR2109, SR
2115, SR2400, SR2410, SR241
1, SH805, SH806A, SH840 and the like are used.

As a method of forming the silicone resin layer, the silicone resin may be applied to the surface of the carrier core particles by a method such as a spraying method or a dipping method as in the conventional method. Since this silicone-coated carrier has a low surface energy as described above, it is possible to extremely reduce the fusion of the toner on the surface due to long-term stirring in the developing device.

In the toner used in the present invention, a polyester resin is used as the binder resin, and a polyester resin synthesized from a bisphenol diol type alcohol and a monomer containing a polyvalent carboxylic acid as a main component is preferable. By using this type of polyester resin, a good toner can be obtained without impairing the vinyl chloride matting resistance and the color of the color material of the color toner. Of course, the fixability at low temperatures is also good. Polyester resin
It is usually obtained by polycondensing a polyol component and a polycarboxylic acid component at a temperature of 180 to 250 ° C in an inert gas atmosphere.

In the present invention, as release agents for toner, free fatty acid type carnauba wax having an acid value of 5 or less, montan ester wax and / or oxidized rice wax having an acid value of 10 to 30 is used. The free fatty acid-type carnauba wax in this case is one in which free fatty acids are desorbed using carnauba wax as a raw material, so that the acid value is 5% or less, and it becomes finer crystals than conventional carnauba wax. The dispersed particle size in the binder resin is 1 μm or less, and the dispersibility is improved.

The montan ester wax is refined from minerals and becomes fine crystals like the carnauba wax, and the dispersed particle diameter in the binder resin is 1 μm or less, and the dispersibility is improved. In the case of montan ester wax, the acid value is particularly preferably 5-14.
The oxidized rice wax is obtained by air-oxidizing rice bran wax. The acid value is preferably 10 to 30, and when it is less than 10, the lower limit fixing temperature rises and the low temperature fixability becomes insufficient, and when it is more than 30, the cold offset temperature rises and the low temperature fixability also becomes insufficient. These waxes may be used alone or in combination and may be 1 to 15% by weight of the total toner, preferably 2 to
Good results are obtained by containing 10% by weight.

Further, in the present invention, as the colorant used in the toner, all of the pigments and dyes conventionally used as the colorant for toner are applied. Specifically, carbon black, lamp black, iron black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6C lake, calcco oil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallyl methane series Any conventionally known dyes and pigments such as dyes and pigments may be used alone or in combination. The amount of these colorants used is usually 1 to 30% by weight, preferably 3 to 20% by weight, based on the binder resin.

In the present invention, the toner may further contain a magnetic material to be used as a magnetic toner. In this case, the magnetic material contained in the magnetic toner includes iron oxide such as magnetite, hematite, and ferrite, iron,
Metals such as cobalt and nickel or these metals and aluminum, cobalt, copper, lead, magnesium, tin,
Examples thereof include alloys with metals such as zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten and vanadium, and mixtures thereof.

These ferromagnetic materials have an average particle size of 0.1 to 0.1.
2 μm or so is preferable, and the amount contained in the toner is about 20 to 200 with respect to 100 parts by weight of the resin component.
Parts by weight, particularly preferably 4 parts by weight per 100 parts by weight of the resin component
0 to 150 parts by weight.

The toner used in the present invention may be mixed with additives as required. As the additive, for example, a tetrafluoroethylene resin, a lubricant such as zinc stearate or cerium oxide, an abrasive such as silicon carbide, or a fluidity imparting agent such as colloidal silica or aluminum oxide, an anti-caking agent, or, for example, There are conductivity imparting agents such as carbon black and tin oxide.

[0031]

EXAMPLES Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. All parts shown below are based on weight.

Example 1 Polyester resin (number average molecular weight Mn = 5000, weight average molecular weight Mw = 55000, glass transition point Tg = 62 ° C.) 81 parts Deleased fatty acid type carnauba wax (acid value 2) 4 parts carbon black ( Mitsubishi Carbon Co. # 44) 12 parts Nigrosine dye (Spirit Black SA: pH = 4.6: Orient Chemical Co., Ltd.) 2 parts

After thoroughly mixing the mixture having the above composition in a Henschel mixer, the mixture was heated and melted by a roll mill at a temperature of 80 to 110 ° C. for about 40 minutes, cooled to room temperature, and the resulting kneaded product was pulverized and classified. A toner having a particle size of 5 to 20 μm was obtained.

Three parts of this toner was coated with a silicone resin (SR-2411: Toray Silicone Co., Ltd.) 1
97 parts of ferrite carrier of 00-250 mesh,
Mixing with a ball mill gave a two-component developer. The charge amount of the toner was +20 μc / g.

Next, a plain paper copying machine (FT-453 manufactured by Ricoh Co., Ltd.) equipped with a Teflon-coated roller as a fixing roller.
When the above developer was set in 0) and a continuous copy test was performed at a heat roller temperature of 130 ° C., a good image was obtained not only at the initial stage but also after 100,000 copies, without causing an offset or winding phenomenon. Neither filming on the photosensitive member nor the developing sleeve was observed.

As a fixing test, hot offset, cold offset, winding occurrence temperature and fixing lower limit temperature were measured, and good results were obtained as shown in Table 1 below. When the toner spent of the developer after 100,000 sheets was measured, no toner spent was recognized.

Comparative Example 1 A developer was obtained in the same manner as in Example 1 except that low molecular weight polypropylene (660P manufactured by Sanyo Chemical Industry Co., Ltd.) was used in place of the released free fatty acid type carnauba wax in Example 1. When a continuous copy test was performed, winding development occurred and a good image could not be obtained.

Example 2 Polyester resin (same as in Example 1) 85 parts Montane ester wax (acid value 12.0) 3 parts Carbon black (# 44 manufactured by Mitsubishi Carbon Co.) 9 parts by the following general formula [IV] Quaternary ammonium salt compound shown 3 parts

[Chemical 4]

The mixture having the above composition was thoroughly stirred and mixed in a Henschel mixer in the same manner as in Example 1, and then it was heated and melted at a temperature of 80 to 100 ° C. for about 40 minutes by a roll mill, cooled to room temperature, and then obtained kneading. 5-20μ
A toner having a particle diameter of m was obtained.

To 3.5 parts of this toner, 96.5 parts of a 50 to 250 mesh iron oxide powder carrier coated with a silicone resin (SR-2410: manufactured by Toray Silicone Co., Ltd.) was mixed in a ball mill to prepare a two-component system. A developer is obtained. The charge amount of the toner was +18 μc / g.

A continuous copy test was conducted in the same manner as in Example 1 using this developer, and good results were obtained as in Example 1. The fixability of this product was good as shown in Table 1 below.

Example 3 In Example 1, an oxidized rice wax having an acid value of 15 was used in place of the released free fatty acid type carnauba wax, and the charge control agent was a nigrosine dye (Special Black E).
B: pH = 7.2: manufactured by Orient Chemical Co., Ltd.), but in the same manner as in Example 1 to obtain a developer.

Next, using this developer, a continuous copy test was conducted in the same manner as in Example 1, and as a result, good results were obtained as in Example 1. The fixability of this product was good as shown in Table 1 below.

Comparative Example 2 A developer was prepared in the same manner as in Example 2 except that the montan ester wax was not used, and a continuous copy test was conducted. As a result, good offset resistance was obtained. However, winding development occurred and a good image was not obtained.

Comparative Example 3 A developer was prepared in the same manner as in Example 1 except that a styrene acrylic resin (SBM-73; manufactured by Sanyo Chemical Industry Co., Ltd.) was used in place of the polyester resin in Example 1. When a continuous copy test was conducted, the fixing lower limit temperature was high and the fixing property was insufficient, so that a good image could not be obtained.

Example 4 In Example 1, a polyester resin (number average molecular weight = 5300, weight average molecular weight = 51000, glass transition point 59.5 ° C.) was used in place of the polyester resin, and the acid value of 4 was released. A developer was obtained in the same manner as in Example 1 except that the fatty acid type carnauba wax was used. The charge amount of the toner was +19.5 μc / g.

Next, a continuous copy test was conducted in the same manner as in Example 1 using this developer, and good results were obtained as in Example 1. The fixability of this product was good as shown in Table 1 below.

Example 5 In Example 4, a montan ester wax having an acid value of 10 was used in place of carnauba wax, and a charge control agent was used as a nigrosine dye (Spirit Black SB: pH).
= 2.2: manufactured by Orient Chemical Co., Ltd.) A developer was obtained in the same manner as in Example 1 except that 1.5 parts were used.

Next, a continuous copy test was conducted in the same manner as in Example 1 using this developer, and good results were obtained as in Example 1. The fixability of this product was good as shown in Table 1 below.

Example 6 Polyester resin (number average molecular weight = 5200, weight average molecular weight = 55000, Tg = 62 ° C.) 85 parts Oxidized rice wax (acid value 12.0) 3 parts Carbon black (Mitsubishi Carbon # 44) 10 parts quaternary ammonium salt compound represented by the following general formula [V] 3 parts

[Chemical 5]

The mixture having the above composition was treated in the same manner as in Example 1 to obtain a toner having a particle size of 5 to 20 μm. Next, a silicone resin (SR-241
97 parts of 100-250 mesh ferrite carrier coated with Toray Silicone Co., Ltd.) were mixed by a ball mill to obtain a two-component developer. The toner charge amount was 19 μc / g.

Next, using this developer, a continuous copy test was conducted in the same manner as in Example 1. As a result, good results were obtained as in Example 1. The fixability of this product was good as shown in Table 1 below.

Comparative Example 4 A developer was obtained in the same manner as in Example 1 except that polypropylene oxide (manufactured by Sanyo Chemical Industry Co., Ltd.) was used instead of the free fatty acid type carnauba wax in Example 1. When a continuous copy test was conducted in the same manner as in Example 1 using the obtained developer, wrapping development occurred and a good image could not be obtained. Further, as shown in Table 1 below, the fixability was sufficient at low temperature, but hot offset occurred and was not at a practical level.

Comparative Example 5 A developer was obtained in the same manner as in Example 1 except that 3 parts of an imidazole derivative (PLZ-7001: manufactured by Shikoku Chemicals Co., Ltd.) was used in place of the charge control agent in Example 1. It was Using the obtained developer, a copy image was produced in the same manner as in Example 1. As a result, fogging occurred in the background portion of the image,
No good image was obtained.

Comparative Example 6 A developer was obtained in the same manner as in Example 1 except that an iron powder carrier of 150 to 250 mesh (manufactured by Nippon Iron Powder Co., Ltd.) was used instead of the silicone-coated carrier in Example 1. It was When a copy image was produced using the obtained developer in the same manner as in Example 1, a good image was initially obtained. However, when a continuous copy test was performed, toner fogging occurred on the background portion, and a good image could not be obtained.

Example 7 A developer was obtained in the same manner as in Example 1 except that 3 parts of a nigrosine dye (pH = 9.1) was used instead of the charge control agent in Example 1. Using the obtained developer,
When a copy image was produced in the same manner as in Example 1, a good image was obtained, and a good image was obtained even after continuous copying. However, when the initial charge amount is +17 μc / g, 10
After copying 10,000 copies, the value was +12 μc / g, which was slightly lower.

Example 8 A developer was obtained in the same manner as in Example 1 except that the quaternary ammonium salt compound represented by the following general formula [VI] was used instead of the charge control agent in Example 1. It was

[Chemical 6]

Using the thus obtained developer, a copy image was produced in the same manner as in Example 1, and a good image was obtained.
Good images were obtained even after continuous copying. However, the charge amount at the initial stage was +16 (μc / g), but after copying 100,000 sheets, it became +11 (μc / g), which tended to be slightly lowered.

Example 9 A two-component type developer was prepared in the same manner as in Example 1 except that 3 parts of ultramarine (oil absorption 23 to 27 ml / 100 g) was used instead of 2 parts of the nigrosine dye. Obtained.
The toner charge amount was +18 μc / g.

Using this developer, a continuous copy test was conducted in the same manner as in Example 1, and as a result, good results were obtained as in Example 1. The fixability of this product was good as shown in Table 2 below.

Comparative Example 7 A developer was obtained in the same manner as in Example 9 except that low molecular weight polypropylene (660P manufactured by Sanyo Chemical Industry Co., Ltd.) was used in place of the released free fatty acid type carnauba wax in Example 9. When a continuous copy test was performed, winding development occurred and a good image could not be obtained.

Example 10 In Example 2, instead of the quaternary ammonium salt,
A two-component type developer was obtained in the same manner as in Example 2 except that the triphenylmethane type dye represented by the following general formula [VII] was used. The toner charge amount is +17 μc / g
Met.

[Chemical 7]

Subsequently, a continuous copy test was conducted using this developer in the same manner as in Example 1, and good results were obtained as in Example 1. The fixability of this product was good as shown in Table 2 below.

Example 11 In Example 9, oxidized rice wax having an acid value of 15 was used in place of the free fatty acid type carnauba wax, and the charge control agent was added to 3.5 parts of ultramarine blue having an oil absorption of 20 to 24 ml / 100 g. A developer was obtained in the same manner as in Example 9 except that the developer was replaced.

Next, a continuous copy test was conducted in the same manner as in Example 1 using this developer, and good results were obtained as in Example 1. The fixability of this product was good as shown in Table 2 below.

Comparative Example 8 A developer was prepared in the same manner as in Example 10 except that the montan ester wax was not used, and a continuous copy test was conducted. As a result, good offset resistance was obtained. However, winding development occurred and a good image was not obtained.

Comparative Example 9 A developer was prepared in the same manner as in Example 9 except that a styrene acrylic resin (SBM-73; manufactured by Sanyo Chemical Industry Co., Ltd.) was used in place of the polyester resin in Example 9. When a continuous copy test was conducted, the fixing lower limit temperature was high and the fixing property was insufficient, so that a good image could not be obtained.

Example 12 In Example 9, instead of the polyester resin,
Number average molecular weight = 5300, weight average molecular weight = 5100
A developer was obtained in the same manner as in Example 9 except that a polyester resin having a glass transition point of 0 and a glass transition point of 59.5 ° C. was used, and a free fatty acid type carnauba wax having an acid value of 4 was used.
The charge amount of the toner was +17.5 μc / g.

Next, a continuous copy test was conducted in the same manner as in Example 1 using this developer, and good results were obtained as in Example 1. The fixability of this product was good as shown in Table 2 below.

Example 13 In Example 12, a montan ester wax having an acid value of 10 was used in place of carnauba wax, and the charge control agent was replaced with an amino group-containing polymer represented by the following general formula [VIII]. A developer was obtained in the same manner as in Example 12 except for the above.

[Chemical 8]

Next, using this developer, a continuous copy test was conducted in the same manner as in Example 1, and good results were obtained as in Example 1. The fixability of this product was good as shown in Table 2 below.

Example 14 Polyester resin (number average molecular weight = 5200, weight average molecular weight = 55000, Tg = 62 ° C.) 69 parts Oxidized rice wax (acid value 12) 4 parts Carbon black (# 44 manufactured by Mitsubishi Carbon Co., Ltd.) 12 parts 15 parts of an amino group-containing polymer compound represented by the following general formula [IX]

[Chemical 9]

The mixture having the above composition was treated in the same manner as in Example 1 to obtain a developer. Note that the toner charge amount is + 18μ
It was c / g.

Next, using this developer, a continuous copy test was conducted in the same manner as in Example 1. As a result, good results were obtained as in Example 1. The fixability of this product was good as shown in Table 2 below.

Comparative Example 10 A developer was obtained in the same manner as in Example 9 except that polypropylene oxide oxide (manufactured by Sanyo Chemical Industry Co., Ltd.) was used instead of the free fatty acid type carnauba wax in Example 9. When a continuous copy test was conducted in the same manner as in Example 1 using the obtained developer, wrapping development occurred and a good image could not be obtained. Further, as shown in Table 2 below, the fixability was sufficient at low temperature, but hot offset occurred and was not at a practical level.

Comparative Example 11 Instead of the silicone carrier in Example 9, 15
A developer was obtained in the same manner as in Example 9 except that an iron powder carrier of 0 to 250 mesh (manufactured by Nippon Iron Powder Co., Ltd.) was used. When a continuous copy image was produced using the obtained developer in the same manner as in Example 1, a good image was obtained in the initial stage. However, when a continuous copy test was performed, toner fogging occurred on the background portion, and a good image could not be obtained.

Example 15 A developer was obtained in the same manner as in Example 9 except that a triphenylmethane dye represented by the following general formula [X] was used instead of the charge control agent in Example 9. ..

[Chemical 10]

Using the thus obtained developer, a copy image was produced in the same manner as in Example 1, and a good image was obtained.
Good images were obtained even after continuous copying. The initial charge amount was +17 μc / g, and the fixability was good as shown in Table 2 below.

The above results are summarized in Tables 1 and 2. The measuring method of each item is as follows.

(1) Offset Occurrence Temperature The toner image transferred onto the copy paper is fixed under the conditions of a roller nip width of 4 mm and a linear velocity of 250 mm / sec while sequentially increasing the roller heating temperature by the Teflon coating roller. By repeating the operation, the temperature at which the background stain occurs is determined, and the lowest temperature at this time is the cold offset generation temperature, and the highest temperature is the hot offset generation temperature.

(2) Entrainment temperature In addition to the case of measuring the offset generation temperature, a so-called solid black original is used to transfer the toner onto almost the entire surface of the copy sheet and sequentially lower the heating temperature of the roller. Similarly, the fixing operation is repeated to obtain the temperature when the copy paper is wrapped around the roller.

(3) Lower limit temperature of fixing The fixing is carried out in the same manner as in the measurement of the offset generation temperature, and the temperature when the toner fixing rate reaches 70% by the clock meter is obtained.

(Evaluation Criteria) A: Very good O: Good X: Bad

[0084]

[Table 1]

[0085]

[Table 2]

[0086]

The positively chargeable developer of the present invention comprises a carrier coated with a silicone resin and a toner containing a binder resin, a release agent and a charge control agent as main components, and the toner is bound to the toner. A polyester resin as a resin, a free fatty acid type carnauba wax having an acid value of 5 or less, a montan ester wax and / or an oxidized rice wax having an acid value of 10 to 30 as a release agent, and a nigrosine type as a charge control agent. Dye, quaternary ammonium salt compound, oil absorption 2
Since it is configured to contain at least one of ultramarine of 7 ml / 100 g or less, triphenylmethane dye, and amino group-containing polymer, (a) it has sufficient offset property and wrapping resistance, and (b) low temperature fixing Since it is possible, high-speed fixing is possible. (D) It has an outstanding advantage that it is possible to stably impart a sufficient positive charging property over a long period of time, and a high-quality image can be formed stably over a long period of time.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the charge amount of toner and the pH of a nigrosine dye.

FIG. 2 is a graph showing a relationship between a toner charge amount and an ultramarine oil absorption amount.

Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G03G 9/10 352 (72) Inventor Yoshihiro Suguro 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Satoshi Miyamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (7)

[Claims] 1. A developer comprising a carrier coated with a silicone resin and a toner containing a binder resin, a release agent and a charge control agent as a main component, and containing at least a polyester resin as the binder resin of the toner. In addition, as a release agent, a free fatty acid type carnauba wax having an acid value of 5 or less, a montan ester wax, and / or an acid value of 10
A positively chargeable developer for developing an electrostatic charge image, which contains 30 oxidized rice wax and further contains a nigrosine dye as a charge control agent. 2. The positively chargeable developer for developing an electrostatic charge image according to claim 1, wherein the nigrosine dye has a pH of 8 or less. 3. The positively chargeable developer for electrostatic image development according to claim 1, wherein the charge control agent contains a quaternary ammonium salt compound in place of the nigrosine dye. 4. The positively chargeable developer for developing an electrostatic image according to claim 3, wherein the quaternary ammonium salt compound is represented by the following general formula [I]. [Chemical 1] 5. The positively chargeable development for electrostatic charge image development according to claim 1, wherein the charge control agent contains ultramarine blue having an oil absorption of 27 ml / 100 g or less in place of the nigrosine dye. Agent. 6. The triphenylmethane dye represented by the following general formula [II] is contained as the charge control agent in place of the nigrosine dye.
The positively chargeable developer for developing an electrostatic image as described above. [Chemical 2] 7. The electrostatic charge image developing device according to claim 1, wherein the charge control agent contains an amino group-containing polymer represented by the following general formula [III] in place of the nigrosine dye. Positively chargeable developer. [Chemical 3]