JPH10282722A - Toner composition for developing electrostatic latent image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the service life of a filter or to unnecessitate the filter and to reduce the running cost of a printer by using a triphenylmethane type electric charge controlling agent as an electric charge controlling agent in a positive charge type toner compsn. used in a flash fixing method. SOLUTION: In a positive charge type toner compsn. used in a flash fixing method and consisting essentially of a bonding resin, a colorant and an electric charge controlling agent, a triphenylmethane type electric charge controlling agent is used as the electric charge controlling agent. Polyester resin is suitable for use as the bonding resin so as to suppress the emission of a malodor by thermal decomposition in a flash fixation. The pref. amt. of the triphenylmethane type electric charge controlling agent is 0.1-5 pts.wt. based on 100 pts.wt. of the toner compsn. In the case of <0.1 pt.wt., satisfactory electrostatic chargeability is not imparted to the toner. In the case of >5 pts.wt., cost increases because the electric charge controlling agent is expensive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing powder (hereinafter referred to as "toner composition") for developing an electrostatic latent image in electrophotography, and more particularly to a laser beam printer which flash-fixes a printing medium at high speed. Alternatively, the present invention relates to a toner composition for developing an electrostatic latent image suitable for an LED printer.

[0002]

2. Description of the Related Art Electrophotography includes a charging step of applying a uniform electrostatic charge to a photoreceptor using a photoconductive substance, an exposure step of irradiating light to form an electrostatic latent image, and a latent image. A developing step of electrostatically attaching toner to the portion, a transferring step of transferring the toner image to a toner image support, a fixing step of fixing the toner image to the toner image support by pressure, heat, flash light, or the like, and a fixing step of remaining on the photoreceptor. A cleaning step for removing the untransferred toner and a charge removing step for removing the electrostatic charge on the photoreceptor and returning it to an initial state are performed, and these steps are repeated to obtain an image.

The pressure fixing method, which is one of the fixing methods for an electrophotographic printer, has advantages that it can be operated immediately, consumes less power because a heater is not used as a heat source, and has no danger of firing at the fixing section. However, there are drawbacks such as poor fixability of the image and low glossiness of the image due to conspicuous glossiness. Therefore, the heat fixing method is generally advantageous. As the heat fixing method, there are known a contact heat fixing method using a hot roll fixing method, and a non-contact heat fixing method using an oven fixing that passes through a heating atmosphere of a flash heater and an electric heater.

The present invention relates to fixing by flash, which is a typical non-contact heat fixing method. In the flash fixing method, an emission spectrum of a xenon lamp, a halogen lamp, or the like is applied to a visible image of a toner in milliseconds or less. (Japanese Unexamined Patent Publication No. Hei 7-107805), in which the toner is softened and melted by the radiant heat to fix the toner to the toner support.

[0005] (1) Since it is non-contact fixing, the resolution of an image during development is not degraded. (2) Quick start is possible without waiting time after turning on the power. (3) Even if recording paper or the like is jammed in the fixing device due to the system down, no fire occurs. (4) Type of toner support (material of recording paper, tack paper,
Good fixability regardless of thick paper). (5) Since only the black toner is heated, the heat shrinkage of the recording paper or the like is small, and the paper is excellent in paper transportability and high-speed printing is possible.

[0006]

However, the flash fixing method has a high rate of energy dissipation to the surroundings due to non-contact heat fixing, and has a higher thermal efficiency than the heat roll fixing due to intermittent energy irradiation. This is a fixing method that consumes a large amount of power due to badness. Further, in the flash fixing method, the surface temperature of the toner composition instantaneously reaches a high temperature of several hundred degrees due to rapid irradiation of flash light of high energy in a very short time, and a part of the additives of the toner composition is decomposed. There is a problem of a decomposition product such as gasification and offensive odor or generation of harmful gas.

Generally, in a flash fixing type printer, in order to remove decomposition products at the time of flash fixing, these decomposition products are sucked in a flash fixing unit and passed through a filter such as activated carbon to adsorb and collect harmful gases. The method has been adopted. However, there has been a problem that the running cost is increased due to the use of the filter and the shortened service life of the filter.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a printer employing a flash fixing system, by suppressing generation of decomposition products,
An object of the present invention is to provide a toner composition for developing an electrostatic latent image, which solves the problem of an increase in running cost due to the fact that a filter is not required or the replacement life of the filter is shortened.

[0009]

According to the present invention, there is provided a toner composition comprising at least a binder resin, a colorant, and a charge control agent used in a flash fixing method, wherein the charge control agent is a triphenylmethane-based charge control agent. And a toner composition for developing an electrostatic latent image.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The toner composition of the present invention comprises at least a binder resin, a colorant, and a charge control agent.

As the binder resin contained in the toner composition of the present invention, known binder resins can be used, for example, polystyrene homopolymer, styrene-isobutylene copolymer, styrene-butadiene copolymer ,
Styrene copolymers such as acrylonitrile-butadiene-styrene copolymer, styrene-acryl copolymer, styrene-methyl methacrylate copolymer, styrene-n-butyl methacrylate copolymer, styrene-glycidyl methacrylate copolymer, polymethyl methacrylate Acrylic homopolymer or copolymer such as polyethyl methacrylate, poly n-butyl methacrylate, polyglycidyl methacrylate, polyethylene terephthalate, fumaric acid / etherified diphenyl polyester, crosslinked polyester with polyhydric alcohol and / or polycarboxylic acid, etc. And polyester resins and epoxy resins. Of these, polyester resins are preferred for reducing odor due to thermal decomposition during flash fixing.

Although not particularly limited, at least 80 mol% of the acid component of the polyester resin is composed of a phthalic dicarboxylic acid, and at least 80 mol% of the alcohol component is a bisphenol A alkylene oxide adduct. A polyester resin obtained from an alcohol component consisting of Further, the softening point is 8 in consideration of the fixing property.
0-130 ° C, glass transition point (Tg) 55-70 ° C,
The temperature at which the melt viscosity obtained by a flow tester reaches 10,000 centipoise is preferably 90 to 135 ° C, and the molecular weight distribution of the polyester resin is such that the number average molecular weight is 2500 to 45 ° C.
The weight average molecular weight is preferably from 7000 to 130,000.

As the colorant contained in the toner composition of the present invention, a known colorant can be used.
For example, in addition to carbon black such as furnace black, acetylene black, and channel black, ferromagnetic fine particles, for example, magnetite fine particles can be used as a one-component toner. It is also possible to use a mixture of ferromagnetic fine particles and carbon black as a black colorant. Dispersion of carbon black in the binder resin among these colorants is important in terms of charge stability of the toner, and a dispersant can be used in combination as needed. Further, the content of carbon black is preferably 2 to 10 parts by weight based on 100 parts by weight of the toner composition. 2
If the amount is less than the weight part, the hiding power of the binder resin is insufficient, and a sufficient image density cannot be obtained. On the other hand, when the amount exceeds 10 parts by weight, it is preferable in order to increase the hiding power of the formed image and increase the image density, but on the other hand, the toner particles are excessively conductive due to the carbon black chain structure formed in the toner particles. Insulation is impaired to become
The chargeability of the toner decreases, and as a result, the image density decreases, and further, white background stain and toner scattering increase.

The charge control agent contained in the toner composition of the present invention is a triphenylmethane charge control agent. Examples of triphenylmethane-based charge control agents include C.I.
I. Solvent Blue 66, 124, C.I. I.
Pigment Blue 61, 56, 19, 18 and the like, and C.I. I. Solvent Blue 124
It is preferable to use Specific examples of such a triphenylmethane-based charge control agent include "Copy Blue" PR and "Brilliant Blue" manufactured by Hoechst.
Base ”SM,“ BASF Alkali Blue ”NBD manufactured by BSF Japan
6156 D LD and the like.

The amount of the triphenylmethane-based charge control agent to be added is 0.1 to 100 parts by weight of the toner composition.
5 parts by weight are preferred. If the amount is less than 0.1 part by weight, sufficient chargeability cannot be imparted to the toner. If the amount exceeds 5 parts by weight, the charge control agent is more expensive than other toner components, leading to an increase in cost.

Here, decomposition products which determine the necessity and life of the filter are generated. However, generation of benzene becomes a problem from the viewpoint of legal regulations. The present inventors have conducted intensive studies on the cause of the generation of this benzene, and as a result,
It was clarified that the nigrosin charge control agent, which is generally used, is decomposed by the light energy of flash fixing to generate benzene.

In general, examples of the charge control agent for giving a positive charge include basic dyes such as dyes, metal salts of higher fatty acids (metal soaps), alkoxylated amines and alkylamides. As a result, the present inventors have found the present invention by diligently studying a charge control agent that does not generate benzene.

If necessary, inorganic fine particles and organic fine particles having an average particle size of 0.005 to 1.0 μm can be added to the toner composition of the present invention as a fluidity improver.
As the inorganic fine particles, fine particles such as silica, titanium oxide, and alumina oxide can be used. Particularly, silica fine particles which have been subjected to a hydrophobizing treatment are preferable in that high fluidity can be reliably obtained. Further, as the organic fine particles, resin fine particles such as polymethyl methacrylate, fluororesin, and silicone resin can be used.

The toner composition used in the present invention can be produced by a conventionally known method. That is, after preliminarily mixing a toner composition such as a binder resin, a colorant, a charge control agent, and, if necessary,
After uniformly dispersing, melting and kneading with a screw extruder, finely pulverizing with a jet mill, and classifying with an air classifier, a desired toner composition can be obtained.

The toner composition of the present invention can be used as a two-component developer by being mixed with a carrier. When the toner composition contains a magnetic material, it can be used as it is as a one-component developer for developing an electrostatic latent image. The carrier is made of a metal such as iron, manganese, cobalt, nickel and chromium, a metal oxide such as chromium dioxide, iron sesquioxide and ferric oxide, and a magnetic material such as ferrite. The ferrite is represented by the general formula MFe204 (M Is Mn,
Co, Mg, Zn or Cu). When the carrier is made of a metal material, it is also preferable to form an oxide film in order to prevent oxidation of the carrier surface. Further, in addition to a magnetite carrier obtained by granulating magnetite fine particles, a so-called resin-type carrier in which magnetite fine particles and a charge control agent are dispersed in a resin can also be used. Further, the same or different resin as the resin contained in the toner composition may be coated on the surface of the carrier for the purpose of improving charging characteristics and the like.

The two-component developer is produced by mixing the toner composition and the carrier described above. The mixing ratio of the toner composition is usually 1 to 1 based on the total amount of the toner composition and the carrier.
The amount is about 5% by weight, which largely depends on the type of carrier, the charging characteristics of the toner used, and the development method. Since the specific surface area of the carrier increases as the particle size of the carrier decreases, the compounding ratio of the toner can be generally increased. If the toner concentration in the developer is too low, the image density becomes low, or the carrier adheres to the photoreceptor, so-called carrier over tends to occur. On the other hand, if the toner concentration is too high, contamination on the inside and outside of the printer due to white background stain on the image background and toner scattering becomes noticeable, so the appropriate toner mixing ratio is determined by actually performing print evaluation with a printer. You.

The electrophotographic toner composition according to the present invention comprises:
Used as an electrophotographic toner composition for flash fixing. Here, it is preferable that the flash fixing method averages the energy applied to the print target by attaching a light shielding plate directly below the lamp.

[0023]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited thereto.

Reference Example 1 (Manufacture of Standard Carrier) Polyester resin ("Tuffton" TTR-2, manufactured by Kao Corporation) 24% by weight Magnetic substance (EPT-1000, manufactured by Toda Kogyo) 74% by weight Charge control agent ("Bontron" S-34: manufactured by Orient Chemical Co., Ltd.) 1% by weight Wax (LUVAX-1151: manufactured by Nippon Seiwa Co., Ltd.) 1% by weight.

After sufficiently mixing the above components, the mixture was melted and kneaded with a twin screw extruder (PCM-30; manufactured by Ikegai Co., Ltd.). After cooling the kneaded material, it is coarsely pulverized by a coarse pulverizer (UG-210KGS: manufactured by Torai Iron Works) into a 2 mmφ pass, and the medium is pulverized by a medium pulverizer (“FINE MILL” FM-300N: manufactured by Nippon New Matchoc Kogyo). After medium pulverization, classification was performed using a fine pulverizer ("Separator" DS-5UR: manufactured by Nippon New Matchc Kogyo Co., Ltd.) to obtain a resin carrier having a weight average particle size of 50 μm.

Example 1 A toner was manufactured using the following components. [Toner composition] Polyester resin ("Tuffton" TTR-2, manufactured by Kao Corporation) 60% by weight Polyester resin ("Tuffton" TTR-5, manufactured by Kao Corporation) 16% by weight Magnetic substance (EPT-1000) 20% by weight Carbon black (manufactured by Cabot; "Regal" 330R) 2% by weight Triphenylmethane-based charge control agent ("Copy Blue" PR, manufactured by Hoechst) 2% by weight.

After sufficiently mixing the above components, the mixture was melted and kneaded with a twin-screw extruder (PCM-30; Ikegai), and then finely pulverized with a jet mill pulverizer (PJM-100; Nippon Pneumatic). Thereafter, the powder was classified with an air classifier (A-12; manufactured by Alpine) to obtain a toner having a weight average particle size of 8 μm. To further improve the fluidity of the toner, a hydrophobic silica fine powder (HVK-215 manufactured by Hoechst Japan KK) is used.
0) was added to the toner in an amount of 1.2% by weight, and mixed with a super mixer (SMV-20; manufactured by Kawata) to prepare a toner, whereby a positively chargeable toner A was obtained.

Next, this toner was blended with 10% by weight and 90% by weight of the resin carrier manufactured in Reference Example 1 to adjust the developer, and a xenon flash fixing type LED printer (GP-1150HE) was used. ), And an image quality was evaluated. Printing was performed on this printer without using a filter. As a result of printing, a good image was obtained. Also, the amount of benzene in the exhaust gas was measured, but there was no significant difference from the ambient atmospheric level of 1 ppb.
It was below the atmospheric fluctuation level (0.3 ppb).

For the measurement of the amount of benzene, 1 L of the gas passing through the filter was collected by a solid collecting method (Carbotrap 400), the collecting tube was set in a thermal desorption apparatus (TDU), and thermal desorption to GC was performed.
-Analyzed by FID method and GC / MS method.

Example 2 In the toner composition of Example 1, "Br" was used instead of the charge control agent.
A toner was prepared in the same manner as above except that illiant Blue Base "SM (manufactured by Hoechst) was used, and a developer was prepared in the same manner. The image quality was evaluated with an LED printer (GP-1150HE), and a good image was obtained as a result of printing, and the amount of benzene in the exhaust gas was measured.
There was no significant difference from the ambient atmospheric level of 1 ppb, which was below the atmospheric fluctuation level (0.3 ppb).

Comparative Example 1 A toner was prepared in the same manner as in Example 1, except that Nigrosine-based charge control agent "Bontron" N-01 was used instead of the charge control agent. Created. Using this developer, an LED printer (GP
-1150HE), and image quality was evaluated. As a result of printing, a good image was obtained. But,
When the amount of benzene in the exhaust gas was measured, it was 9 ppb, which was higher than the atmospheric level (1 ppb), and it was found that it was necessary to use a filter.

Comparative Example 2 A toner was prepared in the same manner as in Example 1, except that "Octope Al" which was a metal soap was used in place of the charge control agent. Using this developer, an LED printer (GP-1150H) adopting a xenon flash fixing method as in Example 1 was used.
In E), an image was displayed and the image quality was evaluated. As a result of printing, a good printed matter could not be obtained because the white background stain was severe. This is probably because good chargeability was not obtained.

[0033]

As described above, by using the toner using the charge control agent of the present invention, the service life of the filter can be extended or the filter can be made unnecessary, so that the running cost of the printer can be reduced.

Claims (3)

[Claims] 1. A positively chargeable toner composition comprising at least a binder resin, a colorant, and a charge control agent used in a flash fixing method, wherein the charge control agent is a triphenylmethane charge control agent. A toner composition for developing an electrostatic latent image. 2. The toner composition for developing an electrostatic latent image according to claim 1, wherein the binder resin is a polyester resin. 3. A toner composition for developing an electrostatic latent image, wherein the energy applied to a printed material is averaged by attaching a light-shielding plate immediately below a lamp in a flash fixing method.