JP2785328B2 - Developer for printer - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention uses a developer used in a printer, in particular, a developer containing a color toner and a developer containing a black toner.
The present invention relates to a developer for a printer used in a printer that performs a reaction development in the order of a color image and a black image on a photoconductor charged to a predetermined polarity.

2. Description of the Related Art As an example of a two-color developing method, a two-color developing method of developing a first latent image with a first toner and then developing a second latent image with a second toner having the same polarity as the first toner It has been known. As shown in FIG. 1, this method adopts a method in which one photosensitive drum rotates during one rotation as shown in FIG.
A method of performing first exposure-first development-second exposure-second development has been proposed.

When the first toner is mixed into the second developer, the color toner is usually used as the first toner and the second toner is used as the second toner in order to minimize the change in hue that occurs when the mixed toner accumulates as the number of copies increases. Use black toner.

This method has the disadvantage that the toner used for the first development gradually mixes into the developer used for the second development, and color turbidity and fogging occur in proportion to the number of copies. This is particularly remarkable in magnetic brush reversal development. In this system, the first toner image already formed on the photoreceptor surface by the first development is rubbed with the magnetic brush ears during the second development, so that the first toner is scraped by the magnetic brush ears of the second development. Into the second developer thus produced, and noticeable color mixture fog and spot fog occur.

On the other hand, the surface potential of the photosensitive drum before the second exposure is increased to prevent color mixture fog and spot fog that may occur during the second development, so that the first toner is not scraped off by the ears of the magnetic brush. A method has been proposed. However,
Even with this method, the first toner mixed as the number of copies increases accumulates in the second developer, and it is not possible to avoid mixed color fog and spot fog.

As a method for preventing the accumulation of the first toner mixed in the second developer, for example, a method in which the first toner and the second toner are positively charged with respect to the carrier, the method in which the first toner is charged in the charging sequence, and the method in which the second toner is charged , Negative one, and utilizing the reversal of the charging polarity of the first toner caused by the mixed friction of the two,
After the first toner is negatively charged and subjected to the second development together, only the second toner is transferred to the negative corona by more positive charging, and the first toner remaining on the photosensitive drum is removed by a cleaner. A method of collecting and excluding it from the system has been proposed. However, if toners having remarkably different chargeability and charge amount distribution are used for the first toner and the second toner, the two
When the two types of toners are mixed, an abnormality occurs in the mutual charge amount, and mixed color fog and spot fog occur.

That is, when a large amount of the first toner is mixed into the second developer, and when the charge amounts of the black toner and the color toner are substantially equal, these toners are developed together, and a color image is particularly formed in a solid image. After being developed, pure black gradually disappears, resulting in an image called so-called mixed color fog. Also, if the color toner is frictionally charged with the black developer after being mixed and the charge is shifted until the polarity becomes opposite to the black toner, then the color toner and the black toner are like toner attached around the carrier. This is developed at the same time and is transferred to paper, resulting in large spots, which is a so-called spot fog noise.

Problem to be Solved by the Invention In the present invention, when performing reversal development in the order of a color image and a black image using a color toner-containing developer and a black toner-containing developer, color toner is mixed into the black toner-containing developer. An object of the present invention is to provide a printer developer comprising an optimal combination of a color toner and a black toner which does not cause color mixture fog or spot fog at the time of transfer.

Means for Solving the Problems The present invention is directed to a printer that uses a color toner-containing developer and a black toner-containing developer and performs reversal development in the order of a color image and a black image on a positively charged photoconductor. In the printer developer used, both the color toner and the black toner contain a polyester resin and a styrene-aminoacrylic resin as a binder resin, and the metal oxide fine particles are mixed and added on the surface of the color toner. Triboelectric charge between the color toner and the carrier used for the black toner-containing developer, which is a positively charged polar color toner and to which the metal oxide fine particles capable of imparting the positive triboelectric chargeability are not added. The present invention relates to a developer for a printer, wherein the amount is between +3 μC / g and −1 μC / g.

Alternatively, the present invention provides a printer developer used for a printer that uses a color toner-containing developer and a black toner-containing developer and performs reversal development in the order of a color image and a black image on a negatively charged photoconductor. Wherein both the color toner and the black toner contain a polyester resin and a styrene-aminoacrylic resin as a binder resin, and the color toner is a metal capable of imparting a negative triboelectric charging property on its surface. A negatively charged polar color toner to which oxide fine particles are mixed and added, and the triboelectric charge amount between the color toner to which the metal oxide fine particles are not added and the carrier used for the black toner-containing developer is -3 μC / g to +1 μC / g.

The color toner-containing developer for forming a color image of the present invention comprises a color toner and a carrier. The color toner is composed of at least a binder resin and a colorant, and the surface of the color toner is mixed and added with metal oxide fine particles.

The binder resin constituting the color toner is generally a thermoplastic resin, and has a glass transition point (Tg) of 45 ° C to 75 ° C.
And a softening point of 70 ° C. to 140 ° C., a styrene-aminoacrylic copolymer resin and a polyester resin can be used.

Styrene monomers that can be used in styrene-aminoacrylic resins include styrene, α-methylstyrene, p-methylstyrene (vinyltoluene),
-T-butyltoluene, p-chlorostyrene and the like. Amino (meth) acrylic monomers are usually represented by the following general formula (I): [In the formula, R ₁ represents hydrogen or a methyl group, R ₂ and R ₃ represent hydrogen or an alkyl group having 1 to 20 carbon atoms, X represents an oxygen atom or a nitrogen atom, and Q represents an alkylene group or an arylene group. ] Is represented. Representative examples of amino (meth) acrylic monomers include N, N-dimethylaminomethyl (meth) acrylate, N, N-diethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N -Diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminobutyl (meth) acrylate, p-N, N-dimethylaminophenyl (meth) acrylate, p-N, N-diethylaminophenyl (meth) acrylate, pN, N-diethylaminophenyl (meth) acrylate, pN, N-dipropylaminophenyl (meth) acrylate, pN, N-dibutylaminophenyl (meth) acrylate , PN-laurylaminophenyl (meth) acrylate, pN-stearylaminop Sulfonyl (meth) acrylate, p-N, N- dimethylamino-benzyl (meth) acrylate, p-N, N- diethylamino-benzyl (meth) acrylate, p-N, N
-Dipropylaminobenzyl (meth) acrylate, p
—N, N-dibutylaminobenzyl (meth) acrylate, pN-laurylaminobenzyl (meth) acrylate, pN-stearylaminobenzyl (meth) acrylate and the like are exemplified. Further, N, N-dimethylaminoethyl (meth) acrylamide, NN-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, NN-diethylaminopropyl (meth) acrylamide, p-N, N- Dimethylaminophenyl (meth) acrylamide, p-N, N
-Diethylaminophenyl (meth) acrylamide, p
-N, N-dipropylaminophenyl (meth) acrylamide, pN, N-dibutylaminophenyl (meth) acrylamide, pN-laurylaminophenyl (meth)
Acrylamide, pN-stearylaminophenyl (meth) acrylamide, pN, N-dimethylaminobenzyl (meth) acrylamide, pN, N-diethylaminobenzyl (meth) acrylamide, pN, N-dipropylamino Benzyl (meth) acrylamide, p-N,
N-dibutylaminobenzyl (meth) acrylamide,
Examples are pN-laurylaminobenzyl (meth) acrylamide, pN-stearylaminobenzyl (meth) acrylamide and the like.

With respect to the copolymer that can be used as a positive charge control agent, the copolymerization ratio of an amino (meth) acrylic monomer and styrene is not particularly limited. In order to impart desired positive charge characteristics to the toner, the amount of the positive charge control agent can be reduced as the copolymerization ratio of the amino (meth) acrylic monomer increases.

As the polyester resin, bisphenol type diol, rosin type diol, and at least one diol component selected from the group consisting of glycol and phthalic acid,
Isophthalic acid, aromatic dicarboxylic acids such as terephthalic acid, and phthalic acid, maleic acid, at least one dicarboxylic acid selected from the group consisting of at least one dicarboxylic acid selected from the group consisting of aliphatic dicarboxylic acids such as adipic acid A polyester resin synthesized from an acid and trimellitic acid can be used.

A polyester resin or a styrene-acrylamino resin generally has its own negative and positive charging properties. By using both of them, the charging effect of various additives contained in the toner (for example, copper −
By canceling the positive charge of phthalocyanine), the charge amount of the color toner described later can be adjusted between +3 μC / g and −1 μC / g.

Those obtained by reacting them with any polymerization catalyst and polymerization method can be used.

Colorants that can be used in color toners include:
For yellow pigments: yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, Hanza yellow G, Hanza yellow 10G, benzidine yellow G, benzidine yellow GR, tartrazine yellow, etc .: for orange pigments: red mouth graphite, Molybdenum orange, permanent orange GTR, benzidine orange G, induslen brilliant orange GK, etc .: For red pigments; , Brilliant Carmine 6B, Eosin Lake, D-Damine Lake B, Akzaline Lake, Brilliant Carmine 3B, etc .: For purple pigments; Manganese Purple Fast Violet B, Methyl Violet Lake, etc .:
For blue pigments: navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, fast sky blue, induslen blue BC, etc .: For green pigments: chrome green, chromium oxide, pigment green B, malachite Green lake, Fanal Yellow Green G, partially chlorinated phthalocyanine, etc .: Although not specifically mentioned here, it is possible to add some oil-soluble dyes for toning or to mix pigments It is.

The color toner may further contain a charge control agent so that the charge amount falls within a desired range. Known charge control agents can be used, for example, quaternary ammonium salts, vinyl pyridine copolymer resins, amino acrylate copolymer resins, positive charge control agents such as nitrogen-containing heterocyclic copolymer resins such as imidazole, metal-containing Negative charge control agents such as oil-soluble dyes and fluorine-containing polymers are exemplified.

The color toner is composed of the binder resin and the colorant, and the production method thereof is not particularly limited, and a known color toner may be applied to produce the color toner.

The untreated color toner thus obtained (a color toner to which no metal oxide fine particles are added).
Means that when a positively chargeable photoreceptor is used, the frictional charge with the carrier used for the developer containing the black toner is +3 μC / g or more.
Those having a value of -1 µC / g, preferably +2.5 to 0 µC / g are used. + 3μC / g triboelectric charge with carrier
If it is larger than that, fog of mixed colors occurs. If it is smaller than -1 μC / g, spot fog occurs. When a negatively chargeable photoreceptor is used, the charge amount of the unprocessed color toner is -3.
μC / g to +1 μC / g, preferably −2.5 to 0 μC / g, is good.

The triboelectric charge amount is a charge amount per unit toner weight when the toner and the carrier are mixed and stirred at a predetermined weight ratio, as described in detail in Examples described later.

In the present invention, such a color toner is surface-treated with metal oxide fine particles. As the metal oxide fine particles, for example, if the photoreceptor is positively chargeable, the metal fine particles can also provide positive triboelectrification so that triboelectrification of the same polarity as the photoreceptor can be provided. Use it as you can.

Specific examples of metal oxides include trade names R-972 and R-9.
Hydrophobic colloidal silica such as 74, R-976, R-811, R-812, R-805; silica surface-treated with a treating agent having an amino group or the like on the surface such as RA200, RA200H, RP-130; Colloidal titania P whose surface is hydrophobically treated as trade name T805; colloidal alumina whose surface is hydrophobized like trade name RX-C; colloidal SiO ₂ · Al ₂ O whose surface is hydrophobized like trade name RX170 _Three mixtures are used (all of them are manufactured by Nippon Aerosil Co., Ltd.).

The above-mentioned silicas have negative triboelectric charging properties, and silica surface-treated with a treating agent having aluminas, titanias and amino groups has positive triboelectric charging properties.

The metal oxide has a size of 5 to 50 μm, preferably 7 to 4 μm.
Fine particles having a particle diameter of 0 μm, more preferably 10 to 30 μm are used.

Metal oxide is 0.01 to 2% by weight based on the color toner
(Wt%), preferably 0.05 to 1.5 wt%, more preferably
The color toner surface is treated in an amount of 0.1 to 1% by weight. 2wt
%, The charge amount becomes too high, and there is no effect on color mixing. If the amount is less than 0.01% by weight, the charge amount becomes low and regular development cannot be performed.

The method of treating the metal oxide on the surface of the color toner may be any of various known methods, for example,
Means such as mixing and stirring the color toner and the metal oxide fine particles can be employed.

However, when the color toner is subjected to the surface treatment as in the present invention, when the color toner is developed, it is properly charged properly, and the color toner is developed only into the electrostatic latent image. Does not occur. In addition, when the color toner adhered on the electrostatic latent image is developed with the black toner-containing developer, the color toner is rubbed by the spikes of the magnetic brush and mixed into the second developing container. The toner does not cause mixed color fog and spot fog of the black toner,
It is immediately removed out of the system. Regarding the mechanism, even if the surface-treated color toner is mixed in the second developing device, the metal oxide fine particles adhering to the surface of the color toner are quickly separated from the surface, and the black toner or the black toner is removed. This is considered to be due to adhesion to the surface of the carrier.

The mechanism by which the metal oxide fine particles on the surface of the color toner are detached when the color toner is mixed with the black toner-containing developer is not clear, but the following facts are considered to be helpful.

-When the color toner is taken into the black developer by the NB method, the higher the mixing ratio of the black toner, the better the color mixing level and the level of separation. The NB method is a method in which the black developer is set and the black toner is neither developed nor replenished, and is developed using only the color toner.

-When black toner is replenished to a developer with a poor color mixture level and separation level in the NB method, separation starts suddenly.

Therefore, in the color toner mixed in the developer containing the black toner, the metal oxide surface-treated on the surface of the color toner by the charge with the black toner or the carrier is transferred to the black toner or the carrier, and the surface of the color toner is Almost no metal oxide. Color toner that has not been surface-treated with a metal oxide is hardly charged even when mixed with a carrier, and such a color toner is not strongly attracted to the carrier. It adheres to the foundation due to the fundamental Waals force or the mirror image force.
In addition, since the color toner attached to the photoconductor is hardly charged, it is not attracted to the paper due to the charging at the time of transfer, so it remains on the photoconductor and is removed from the photoconductor in the next cleaning step. Therefore, it is separated from the black developing device.

As the carrier constituting the first developer together with the color toner, a known carrier used in the magnetic brush developing method can be used, and for example, ferrite, fine iron or a binder type microcarrier may be applied.

A black toner-containing developer for forming a black image is composed of a black toner and a carrier. The black toner includes at least a binder resin, a colorant (black), and a charge control agent, and the surface of the black toner may be surface-treated with fine metal oxide particles according to the purpose.

The black toner differs from the color toner in that it further contains a charge control agent and uses a black colorant as the colorant, but the binder control and metal oxide fine particles are described in the color toner. The same ones as described above can be applied. The production method is not particularly limited.

Examples of the black pigment used for the black toner include carbon black (channel black, furnace black, acetylene black, lamp black, etc.), activated carbon, and aniline black.

The charge control agent is not particularly limited as long as it has a chargeability of the same polarity as that of the photoreceptor, and the same charge control agent as described for the application to the color toner can be used. Because of the black toner, a colored charge control agent can be used.

 The two-color developing method will be described with reference to FIG.

The electrophotographic copying method itself shown in FIG. 1 is already known, and a main charger (11), a first exposure device (12), and a first developing device (1) are provided around a photosensitive drum (10).
3), second charger (14), second exposure device (15),
A second developing device (16), a transfer charger (17), a cleaning blade (18), an eraser lamp (19) and the like are attached.

First, the surface of the photoconductor drum (10) is charged by the main charger (11). The voltage is in the normal range, e.g. 500-1000V
It is. Depending on the type of photoreceptor, the charge is + or-
May be. An appropriate selection may be made according to the purpose of use. A first latent image is formed by irradiating a laser beam or the like, and then reversely developed by a first developing device using a two-component magnetic developer containing a color toner and a carrier. Next, using a second scorotron charger (14), the surface potential is made uniform, and then a second exposure is performed with a laser beam or the like to form a latent image, and a two-component system containing a black toner and an arbitrarily selected carrier is used. Reverse development is performed using a magnetic developer. At this time, a part of the color toner is scraped off by a spike of a magnetic brush and mixed into the black developer, but the adverse effect of the mixed toner is solved by the present invention.

 Hereinafter, the present invention will be described with reference to examples.

Example Preparation of Black Toner (Toner A ′) Parts by weight Bisphenol-based polyester 95 (Mw / Mn 22.4, Mw: 216,300, AV; 25.3, Tg: 62.3 ° C.) Styrene-dimethylaminoacrylate copolymer resin (Mw / Mn:
5.8, Mw: 82,100, amine value: 288) 5 Carbon black # 445 (Mitsubishi Kasei Co., Ltd.) Charge control agent Bontron N-055 (Made by Orient Chemical Industries) Put the above materials in a Henschel mixer, After sufficient mixing, the mixture is melt-kneaded with a twin-screw extruder. After cooling, after coarse crushing of 3 mm or less, the average particle size is 13.4 μm with a jet crusher.
After crushing into fine particles, the particles are classified using a rotary wind-type classifier, and the average diameter
13.0 μm of toner A was obtained.

Next, a hydrophobic silica (R-976:
Surface treatment was carried out at a ratio of 0.2 wt% to toner A (manufactured by Nippon Aerosil Co., Ltd.).

 The toner thus obtained is referred to as toner A '.

Preparation of black toner (toner B ′) parts by weight Styrene-acrylic resin 96 (Mw / Mn: 23.5, Mw: 187,700, AV: 17.3 Tg: 64.3 ° C.) Styrene-dimethylaminoacrylate copolymer resin (Mw / Mn: 62.900, amine value: 178) 4 Carbon bracket # 445 (Mitsubishi Kasei Kogyo Co., Ltd.) Charge control agent Bontron N-055 (Orient Chemical Co., Ltd.) The above materials were treated in the same manner as toner A. A toner B having an average diameter of 12.8 μm was obtained. The surface of this toner was coated with hydrophobic silica R972 (manufactured by Aerosil Co.) with toner
Surface treatment was performed at a ratio of 4 wt%.

 The toner thus obtained is referred to as a toner B '.

Preparation of Color Toner (Toner C ′ (Blue Toner)) Parts by weight Bisphenol-based polyester 87 (Mw / Mn: 22.4, Mw: 216,300, AV: 25.3, Tg: 62.3 ° C.) Styrene-dimethylaminoacrylate copolymer resin (Mw
/ Mn: 5.8, Mw: 82,100, amine value: 288) 13 Cu-phthalocyanine (# 4920: manufactured by Daiichi Nippon Kasei Co., Ltd.) 5 The above material was treated in the same manner as toner A, and blue having an average diameter of 13.0 μm was obtained. Toner C was obtained. A hydrophobic alumina RX-C (manufactured by Nippon Aerosil Co., Ltd.)
Was treated at a rate of 0.3 wt%.

 The toner thus obtained is referred to as a toner C ′.

Toner D '(blue toner) parts by weight Styrene-acrylic resin 95 (Mw / Mn: 21.3, Mw: 213,000) Styrene-aminoacrylic resin 5 (Mw / Mn: 6.4, Mw: 62,900, amine value: 178) Copper -Phthalocyanine 5 (# 4920: manufactured by Dainichi Seika Co., Ltd.)
A blue toner D of 13.2 μm was obtained. The surface of the toner was treated with hydrophobic silica R976 (manufactured by Nippon Aerosil Co., Ltd.) and hydrophobic titanium dioxide T-805 (manufactured by Nippon Aerosil Co., Ltd.) at a ratio of 0.3% by weight and 0.2% by weight to toner D, respectively.

 The toner thus obtained is referred to as a toner D '.

Carrier preparation parts by weight Styrene-acrylic resin 100 (Priolite ACL: manufactured by Goodyear) Magnetic powder Mapico Black BL-500 200 (magnetite: manufactured by Titanium Co., Ltd.) The mixture was melt-kneaded with this roll, cooled and pulverized. Next, the resulting mixture was classified to have an average diameter of 37 μm to obtain a binder-type carrier.

Preparation of Developer 92 parts by weight of a binder-type carrier (37 μm) was added to 8 parts by weight of each of the black toner (toner A ′, toner B ′) and color toner (toner C ′, toner D ′) prepared as described above. Was placed in a plastic container and stirred at 120 rpm for 2 hours to prepare a developer. On the other hand, an unprocessed color toner (toner C, toner D) was mixed at the same weight ratio as the above microcarrier to prepare a developer, and the charge amount was measured.

 Table 1 shows the obtained results.

Actual machine test Using a color toner as the first toner and a black toner as the second toner, an actual machine test was conducted on mixed color fog and spot fog.

The two-color developing device used has the configuration shown in FIG. 1. The outline of the device and the measurement conditions (the conditions are different depending on the characteristics of the toner and are shown together) are as follows.

Photoreceptor drum: selenium-based photoreceptor, 1st development: magnetic brush method (microtoning method) 2nd development: magnetic brush method (microtoning method) Transfer charger: applied voltage +5 kV Main charger: applied voltage +6 kV Second charger: grid Voltage + 600V Using the above apparatus, the transferred image after 10,000 copies was visually observed with the naked eye, and the color mixture fog was evaluated as follows. The results are shown in Table 2.

Effect of the Invention According to the present invention, fog (mixed color fog, spot fog)
Black and color copy images can be obtained without causing any problems.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of an apparatus for applying the developer of the present invention.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-52-123622 (JP, A) JP-A-61-126565 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/087 G03G 9/097

Claims (2)

(57) [Claims] Claims: 1. A printer developer for use in a printer which uses a color toner-containing developer and a black toner-containing developer for reversal development in the order of a color image and a black image on a positively charged photoconductor. Wherein both the color toner and the black toner contain a polyester resin and a styrene-aminoacrylic resin as binder resins, and the color toner is a metal capable of imparting a positive triboelectric charging property on its surface. The toner is a positively charged polar color toner to which oxide fine particles are mixed and added, and the triboelectric charge between the color toner to which the metal oxide fine particles are not added and the carrier used for the black toner-containing developer is +3 μC / g. A developer for a printer, wherein the developer concentration is between -1 μC / g and -1 μC / g. 2. A developer for a printer which uses a color toner-containing developer and a black toner-containing developer and performs reversal development in the order of a color image and a black image on a negatively charged photoconductor. Both the color toner and the black toner contain a polyester resin and a styrene-aminoacrylic resin as binder resins, and the color toner has a metal oxide capable of imparting a negative triboelectric charging property on its surface. Is a negatively charged polar color toner to which mixed fine particles are added, and the triboelectric charge amount between the color toner to which the metal oxide fine particles are not added and the carrier used for the black toner-containing developer is -3 μC / g. A developer for a printer, wherein the developer concentration is in the range of -1 μC / g to +1 μC / g.