JPH11327213A - Positively chargeable toner and developer using the same - Google Patents

Abstract

(57) [Abstract] (with correction) [PROBLEMS] To provide a positively chargeable toner capable of obtaining a good printed image with a small change in the charge amount of the toner and a developer using the same. SOLUTION: In a positively chargeable toner containing a binder resin as a main component, a nigrosine dye and a quaternary ammonium salt are used as charge control agents. The positively chargeable toner contains a polyester resin as a binder resin, a polypropylene wax as a release agent, and carbon as a colorant. In the toner material particles containing no external additive, the content of the nigrosine dye is 2 to 5% (% by weight, the same applies hereinafter), and the content of the quaternary ammonium salt is 0.25 to 2%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a positively chargeable toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, and a developer using the same.

[0002]

2. Description of the Related Art Various developing methods for visualizing an electrostatic latent image using a toner are known, and they are roughly classified into a dry developing method and a wet developing method. Of these, the dry developing method does not use a liquid developer unlike the wet developing method, so that no odor is generated,
Further, it has a feature that it does not require high energy for drying a transfer material and is suitable for high-speed transfer, and is widely used as a mainstream developing method of a copying machine, a facsimile, a printer, and the like.

The dry developing method includes a method using a two-component developer and a method using a one-component developer. The method of using a one-component developer containing only toner and not containing a carrier does not have the problem of deterioration of the carrier and fluctuation of the image due to the fluctuation of the mixing ratio of the toner and the carrier, but the expensive black magnetic powder in the toner particles. Since it contains a large amount of a body (magnetite or the like), there is a problem that not only the cost is increased but also it is difficult to obtain a clear color.

[0004] On the other hand, the method using a two-component developer is an excellent method capable of coping with colorization and obtaining a good image relatively stably. In a toner used for a two-component developer, a nigrosine dye, a basic dye, a monoazo dye, or the like is used as a charge control agent for imparting chargeability.
Among these, a nigrosine dye is preferably used in terms of chargeability and cost.

[0005]

However, it is difficult to control the production conditions of a nigrosine dye, and it is difficult to obtain a composition having a constant composition. Therefore, there is a large variation in pH between lots, and the amount of charge transfer changes accordingly. Therefore, there is a problem that the charge amount of the toner fluctuates and a good printed image cannot be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and a positively chargeable toner capable of preventing a change in the charge amount of a toner and obtaining a good image. It is intended to provide a developer using the same.

That is, the present invention relates to a positively chargeable toner containing a binder resin as a main component, wherein the positively chargeable toner contains a nigrosine dye and a quaternary ammonium salt as a charge control agent. 2. The toner according to claim 1, wherein the positively chargeable toner contains a polyester resin as a binder resin, a polypropylene wax as a release agent, and carbon as a colorant. Nigrosine dye content of 2-5% (wt%, the same applies hereinafter), quaternary ammonium salt content of 0.25-2%
The toner according to claim 1, wherein the toner is
4. A positively chargeable two-component developer comprising the toner and the carrier according to 2 or 3 (Claim 4), and the carrier is magnetite whose surface is coated with a fluororesin.
The present invention relates to the developer described in claim 5, and the developer according to claim 4, wherein the content of the carrier is 94 to 97% and the content of the toner is 3 to 6%.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The positively chargeable toner of the present invention is a toner containing a binder resin as a main component.

The binder resin has a function of fixing to paper and an anti-offset property. Examples thereof include a polyester resin; an epoxy resin; a polyamide resin; a styrene-methyl (meth) acrylate copolymer, and styrene-ethyl. Styrene-acrylic resins such as (meth) acrylate copolymer, styrene-butyl (meth) acrylate copolymer, and styrene-hydroxypropyl (meth) acrylate copolymer; and polyolefin resins such as polypropylene and polyethylene. Among them, polyester resins are preferred because they are easily positively charged and do not dissolve in a plasticizer or the like contained in a contact surface with a printing surface after fixing.

Here, the polyester resin is obtained by polycondensation of an alcohol monomer and a carboxylic acid monomer.

Examples of the alcohol monomer include dihydric alcohols such as aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and butanediol;
Alicyclic diols such as 1,4-bis (hydroxymethyl) cyclohexane and hydrogenated bisphenol A, aromatic diols such as bisphenol A, and trihydric or higher polyhydric alcohols include, for example, sorbitol, hexane tetrol, Sorbitan, pentaerythritol, sucrose, butanetriol, pentanetriol, glycerol, trimethylolpropane and the like can be mentioned.

Examples of the carboxylic acid monomer include dicarboxylic acids such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, malonic acid, and these acids. Anhydrides, linoleic acid dimers (dimer acids) and trivalent or higher polycarboxylic acids such as benzenetricarboxylic acid (trimellitic acid), cyclohexanetricarboxylic acid, naphthalenetricarboxylic acid, butanetricarboxylic acid, hexanetricarboxylic acid, etc. Is raised. Among them, it is preferable to use at least one of terephthalic acid and trimellitic acid in view of development characteristics and charging characteristics.

Specific examples of the polyester resin include:
Crosslinked polyester resin FT-006 manufactured by Nippon Carbide Industry Co., Ltd., which uses an aromatic diol such as bisphenol A as an alcohol component and trimellitic acid and terephthalic acid as an acid component is preferable.

Although the molecular weight of the binder resin is not particularly limited, the weight average molecular weight is 5,000 to 100,000.
It is preferred that When it is less than 5,000, offset tends to occur at low temperatures, and when it exceeds 100,000, the fixability to paper tends to deteriorate.

Here, the weight-average molecular weight refers to a value of 0.1% of the sample.
It is a value measured by gel permeation chromatography using a 2% tetrahydrofuran solution.

The fact that the binder resin is the main component means that the amount of the binder resin added is 85 to 98%, more preferably 90 to 95%, in the toner material particles containing no external additives. . If it is less than 85%, the fixability to paper decreases, and
%, The amount of other ingredients is too small,
Charging and coloring become difficult.

The positively chargeable toner is used as a two-component developer by being mixed with a carrier, and contains a positive charge control agent as a charge control agent.

The charge control agent refers to a charge control agent that imparts a charge amount necessary for developing the toner by attaching toner to an electrostatic latent image formed on a photoreceptor.
A nigrosine dye and a quaternary ammonium salt are used in combination as a positive charge control agent.

The above-mentioned nigrosine dye is called an azine compound, and is, for example, N-produced by Hodogaya Chemical Industry Co., Ltd.
01, N-04, N-07, N-13 and the like.

The quaternary ammonium salt is a compound consisting of an amine compound having four alkyl groups or allylalkyl groups and an organic acid, for example, P-51 manufactured by Orient Chemical Industries, and Hoechst Japan K.K. VP
-2038.

For the nigrosine dye and the quaternary ammonium salt, a combination of N-13 manufactured by Hodogaya Chemical Industry Co., Ltd. and P-51 manufactured by Orient Chemical Industry Co., Ltd. can provide an appropriate charge level. preferable.

The contents of the nigrosine dye and the quaternary ammonium salt in the toner material particles containing no external additives are 2 to 5% and 0.25 to 1.0%, and the weight ratio of both is 12: It is preferably 1-2: 1.

If the amounts of the nigrosine dye and the quaternary ammonium salt are less than the above, a sufficient amount of positive charge cannot be obtained. Conversely, if the amounts are more than the above, the charge tends to rapidly decrease. On the other hand, if the content ratio of the two is more than 12: 1, the variation in the amount of charge increases, and if the content ratio is less than 2: 1, the white color of the quaternary ammonium salt appears and it becomes difficult to produce clear colors. Tend.

In addition to the binder resin and the charge control agent described above, a colorant (pigment or dye), a release agent,
An external additive or the like may be contained.

Examples of the coloring agent include pigments such as carbon black, aniline black, acetylene black, naphthol yellow, red iron oxide, and phthalocyanine blue, and azo dyes and anthraquinone dyes. In the case of a black toner, carbon black is preferred because a clear black is obtained with a small amount and the electric resistance of the toner can be adjusted by the amount of addition.

The content of the colorant in the toner material particles is preferably 2 to 10% from the viewpoint of the color tone and the electric resistance of the toner.

Examples of the definition improver include polyolefin wax such as polyethylene and polypropylene, fatty acid ester, higher fatty acid, paraffin wax, silicone varnish and the like. Above all, JISK 2531-1960 is excellent in releasing property.
The softening point is 80 when measured by the ring and ball method specified in
Polyethylene and polypropylene having a temperature of up to 160 ° C. are preferred, and polypropylene is more preferred. The content of the fixability improving agent is usually preferably 0.5 to 3%.

The above-mentioned external additive is mixed with toner material particles for imparting fluidity.
Examples include alumina, titanium oxide, cerium oxide, chromium oxide, strontium titanate, and calcium titanate. Among them, silica and alumina having a particle diameter of 0.01 to 0.5 μm are used in an amount of 0.1 to 0.5% with respect to 100% of the toner material particles in order to improve the fluidity with little change due to environmental conditions.
It is preferable to contain 3%.

The toner of the present invention can be produced, for example, by the following method. That is, the binder resin, the charge control agent, and other additives as necessary are preliminarily mixed and kneaded while being melted using, for example, an extruder. Thereafter, the mixture is cooled and coarsely pulverized using, for example, a hammer mill or a Wiley type pulverizer. Further, the material is finely pulverized using, for example, a jet mill, and then classified to obtain toner material particles having a desired particle size.

Next, if necessary, mechanical energy due to an impact force is repeatedly applied to the toner material particles in a gas phase by using a surface treatment apparatus having an improved impact-type pulverizer, for example. The sphering treatment can be performed without substantially pulverizing the resin particles.

The spheroidizing treatment of the toner material particles may be performed at room temperature, or may be performed while heating to slightly soften the particles. However, if the heating temperature is too high, the adhesiveness of the binder resin increases, and as a result, a phenomenon occurs in which the particles aggregate and agglomerate, and it is difficult to obtain a toner having a desired particle size distribution.

The average particle size of the toner material particles is preferably from 5 to 20 μm, and more preferably from 7 to 15 μm, in order to form a high-resolution image without deteriorating the cleaning property or causing toner scattering. More preferred.

In order to obtain toner having uniform characteristics, it is preferable that the particle size distribution is narrow, specifically, 90%
It is preferable that the above particles are in the range of 0.5 to 1.5 times the average particle size. Here, the average particle size and the particle size distribution of the particles are measured using “Coulter counter, TYPE TAII” (manufactured by Coulter Electronics Co., Ltd.), and the average particle size means the value when the weight accumulation becomes 50%. Refers to particle size.

The toner material particles are usually used as a two-component toner by mixing an external additive. Examples of the method of mixing the external additive include a batch-type dry high-speed mixing and a surface-embedding type mixing. Of these, batch-type dry high-speed mixing is preferred in terms of uniform adhesion and high fluidity.

Preferred specific examples of the positively chargeable toner of the present invention include the following examples.

A polyester resin is used as a binder resin, a polypropylene wax is used as a fixing property improving agent (release agent), carbon is used as a coloring agent, and 2 to 5% of a nigrosine dye and 0.25 to 2 of a quaternary ammonium salt are used as a charge controlling agent. % Of the toner material particles obtained by adding silica as an external additive.

The developer using the positively chargeable toner of the present invention is a mixture of the above positively chargeable toner and a carrier.

Here, as the carrier, the surface of the core agent is used in order to reduce the durability and the environment dependence of the charging characteristics.
A fluororesin solution coated by a spray method or the like is used.

Examples of the core agent include magnetite (Fe ₃ O ₄ ), ferrite (Fe ₂ O ₃ ), iron powder and the like. Among them, magnetite and ferrite are preferred in terms of controlling magnetic properties and controlling electric resistance.

If the particle size of the carrier is too small, carrier development is likely to occur, and if it is too large, the developability tends to decrease, so that it is preferably 40 to 150 μm.

The mixing ratio (weight ratio) of the carrier and the toner in the developer is 94: 6-97: carrier: toner.
A value of 3 is preferred because the generation of fog when the number of carriers is small and the decrease in image density when the number of carriers is large can be suppressed.

A preferred specific example of the developer of the present invention is a developer obtained by mixing 94 to 97% of magnetite having a fluororesin coated on its surface as a carrier with the positively chargeable toner obtained as described above. is there.

[0043]

EXAMPLES Next, the present invention will be described based on examples, but the present invention is not limited to these examples.

Examples 1-4, Comparative Examples 1-5 Polyester resin (FT-006, weight average molecular weight: 20,000, manufactured by Nippon Carbide Industry Co., Ltd.) as a binder resin,
Polypropylene wax (weight average molecular weight 5000, Viscol 550P, Sanyo Chemical Industries, Ltd.) as a release agent
Nigrosine dye (azine compound dye, N-13 manufactured by Hodogaya Chemical Industry Co., Ltd.) and a quaternary ammonium salt (P-51, Orient Chemical Industry Co., Ltd.)
Carbon black (diamond black MA-1)
00, manufactured by Mitsubishi Chemical Corporation) at a ratio shown in Table 1, and a twin-screw kneader (PCM-30,
(Ikegai Co., Ltd.).

The mass of toner obtained by cooling and solidifying is
The powder was pulverized by a mechanical pulverizer (Turbo Mill, manufactured by Turbo Kogyo Co., Ltd.) and classified by a classifier (DS type, manufactured by Nippon Pneumatic Industries Co., Ltd.) to obtain toner material particles having an average particle diameter of 10 μm.

Next, silica (BET specific surface area: 120 m ² / g, H
0.3 parts of 2000/4, Hoechst Japan Co., Ltd.) were uniformly mixed using a mixer (Super Mixer, manufactured by Kawata Co., Ltd.) to obtain a toner.

5% of the obtained toner and 95% of a fluorine-coated magnetite carrier were mixed to prepare a developer. The developer was set in a high-speed printer (40 to 50 sheets / min) with a heat roller fixing, and 10,000 sheets of a 5% chart image were printed. The charge amount of the developer and the image density and fog of the obtained printed matter were measured according to the following methods. Table 1 shows the results.

In the comprehensive judgment column in the table, ○ indicates good, Δ indicates slightly inferior, and × indicates inferior.

(A) Image Density The image density of the copy print was measured at five equally divided sections using a Macbeth densitometer, and the average value was defined as the image density.

(B) Fog The color difference meter (Z- # 9) is used for paper (white paper) before and after printing.
0, manufactured by Nippon Denshoku Industries Co., Ltd.), and the presence or absence of fogging (coloring of a white color originally) was observed on a printed matter printed in solid white.

(C) Charge Amount The developer on the sleeve of the developing machine was sampled, and the charge amount of the toner was measured by a blow-off charge amount measuring device.

[0052]

[Table 1]

From the results shown in Table 1, it can be seen from Examples 1 to 4 that a nigrosine dye and a quaternary ammonium salt were used in combination as a charge controlling agent.
In the developer of the present invention No. 4, compared with Comparative Examples 1 to 3 in which a nigrosine dye or a quaternary ammonium salt, which was conventionally known as a charge controlling agent, was used alone, the image density was still higher after printing 10,000 sheets. It can be seen that both the decrease in the charge and the increase in the charge amount are suppressed. Examples 1 to 4 in which the weight ratio of the nigrosine dye to the quaternary ammonium salt is 12/1 to 2/1.
It can also be seen that the developer of No. 4 is superior to Comparative Examples 4 and 5, which are out of this range.

[0054]

According to the developer using the positively chargeable toner of the present invention, fluctuation of the charge amount can be prevented, and as a result, a stable and good image can be obtained.

Claims (6)

[Claims] 1. A positively chargeable toner comprising a binder resin as a main component, comprising a nigrosine dye and a quaternary ammonium salt as charge control agents. 2. A positively chargeable toner comprising: a polyester resin as a binder resin; a polypropylene wax as a release agent;
2. The toner according to claim 1, which contains carbon as a coloring agent. 3. A toner material particle containing no external additive, wherein the content of a nigrosine dye is 2 to 5% by weight, and the content of a quaternary ammonium salt is 0.25 to 2% by weight, and the weight ratio of the two. A nigrosine dye / quaternary ammonium is 12/1 to 2;
The toner according to claim 1, wherein the ratio is +1. 4. A positively chargeable two-component developer comprising the toner according to claim 1, 2 or 3, and a carrier. 5. The developer according to claim 4, wherein the carrier is magnetite whose surface is coated with a fluororesin. 6. A carrier content of 94 to 97% by weight,
The developer according to claim 4, wherein the content of the toner is 3 to 6% by weight.