JP2792101B2 - 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 for a printer that performs reversal 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, the charge amount becomes abnormal with each other, resulting in mixed color fog and spot fog.

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, the pure black is gradually not reproduced and becomes 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. Since they are electrostatically attracted and developed at the same time and transferred to paper, they become large spots and cause 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, the color toner is a positively-chargeable color toner in which negatively-chargeable fine particles and positively-chargeable fine particles are mixed and added on the surface, and each of the negatively-chargeable fine particles and the positively-chargeable fine particles is used. And the triboelectric charge between the color toner to which the fine particles are not added and the carrier used in the black toner-containing developer is +3 μm.
The present invention relates to a developer for a printer, which is between C / g and -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 comprises at least a binder resin and a colorant, and the surface of the color toner is treated with positively charged fine particles and negatively charged 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.
There is no particular limitation as long as it has a softening point of 70 ° C. to 140 ° C., but styrene or styrene-acrylic copolymer resins, polyester resins, epoxy resins and the like can be used.

Monomers that can be used for the styrene-acrylic resin include styrene-based monomers such as styrene, α-methylstyrene, p-methylstyrene (vinyltoluene), pt-butyltoluene, and p-chlorostyrene. Body, (meth) acrylic acid (meaning acrylic acid or methacrylic acid; the same applies hereinafter), methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acryl Monofunctional vinyl monomers such as butyl acrylate, cyclohexyl (meth) acrylate, (meth) acrylonitrile, (meth) acrylamide, hydroxypropyl (meth) acrylate and vinylpyridine
Species or two or more species.

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

Examples of the polyester resin include at least one diol component selected from the group consisting of bisphenol-type diol, rosin-type diol and glycol, and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, and phthalic acid and maleic acid. A polyester resin synthesized from 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 and trimellitic acid may be used. it can.

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, indus len brilliant orange GK, etc .: For red pigments; red pigment; Brilliant Carmin 6B, Eosin Lake, D-Dammin Lake B, Akzaline Lake,
Brilliant Carmine 3B etc .: For purple pigments; Manganese purple, Fast Violet B, Methyl Violet Lake etc .: For blue pigments; 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 use a mixture of pigments. It is possible.

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 unprocessed color toner (color toner to which the positively charged fine particles and the negatively charged fine particles are not mixed and added) thus obtained is used as a black toner-containing developer when a positively charged photoconductor is used. The triboelectric charge amount with the carrier used is +3 μC / g to −1 μC / g, preferably +2.5 to 0
A value indicating μC / g is used. When the amount of triboelectric charge with the carrier is greater than +3 μC / g, mixed-color fog occurs. When the amount is less than −1 μC / g, spot fog occurs.

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 treated with negatively charged fine particles and positively charged fine particles. It is not clear why simultaneous treatment with both positively and negatively charged fine particles is effective, but the color toner mixed into the black developer causes new frictional charging with the black toner and carrier. At this time, the charge amount of the color toner with a small amount and the black toner split and become equilibrium. At that time, depending on the magnitude of the respective charge amounts, the positively charged fine particles may separate from the color toner, or the load charge may be reduced. It is considered that the fine particles of the toner have come off and work to lower the charge amount of the color toner.

The negatively charged fine particles include hydrophobic silica fine particles, and the positively charged fine particles include hydrophobic titania fine particles, hydrophobic alumina fine particles, and positively charged fine particles.

Specific examples of the hydrophobic silica fine particles include trade name R-97.
2, hydrophobic colloidal silica such as R-974, R-976, R-811, R-812, and R-805; specific examples of fine particles treated with positive charge include trade names RA200, RA200H, and RP-130. Silica surface-treated with a treating agent having an amino group or the like on its surface;
As a specific example of the hydrophobic titania fine particles, colloidal titania P whose surface is subjected to a hydrophobic treatment such as trade name T805; as a specific example of the hydrophobic alumina fine particles, the surface is subjected to a hydrophobic treatment as a trade name RX-C. Colloidal alumina; trade name
A colloidal SiO ₂ / Al ₂ O ₃ mixture or the like that has been subjected to a hydrophobic treatment like RX170 is used (all of these are manufactured by Nippon Aerosil Co., Ltd.).

Both positively and negatively charged fine particles have a size of 5 to 50 mμ.
m, preferably 7 to 40 mμ, more preferably 10 to 30 mμ
m particles are used.

When the photoreceptor is used with a positive charge, the positively charged fine particles are 0.2 / 1 to 1/1, preferably 0.
3 to 1, and the total amount is 0.05 to 2% by weight (wt%), preferably 0.1 to 1% by weight, based on the color toner. The ratio is
When the ratio is less than 0.2 / 1, the charge is insufficient and the background fog is remarkable. When the ratio is greater than 1, the charge is too high and mixed color fog occurs. Each of the positively and negatively charged fine particles is 0.05 to 1% by weight (wt%), preferably 0.1% by weight, based on the color toner.
The color toner surface is treated in an amount of 1 to 0.7 wt%. If the mixing amount is less than 0.05 wt%, mixed color fog becomes remarkable and 2w
If it is more than t%, spot fog becomes remarkable. If the mixing ratio of positively charged color is less than 0.05% by weight, the charge is insufficient and the background fog becomes remarkable. If it is more than 1 wt%, mixed color fog and spot fog become remarkable.

As a method of treating the positively charged fine particles and the negatively charged fine particles on the surface of the color toner, various known methods may be applied, for example, mixing and stirring the color toner with the positively charged fine particles and the negatively charged fine particles And other means.

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. As for the toner, the mixed color fog of the black toner does not cause spot fog,
It is quickly removed out of the system. Regarding the mechanism, even if the surface-treated fog enters the second developing device,
It is considered that the positively charged fine particles and the negatively charged fine particles adhering to the surface of the color toner quickly detach from the surface and adhere to the black toner and the surface of the carrier.

The mechanism by which the positively charged fine particles and the negatively charged fine particles on the surface of the color toner are detached when the color toner is mixed into the black toner-containing developer is not clear, but the following facts are helpful. Think of things.

・ When color toner is taken into black developer by NB method,
The higher the mixing ratio of the black toner, the better the color mixing level and the level of separation.

Note that NB is a method of developing with only color toner without developing or replenishing black toner with the black developing device set.

-The black toner is replenished to the developer with the poor color mixture level and separation level of the NB method, and sudden separation starts.

Therefore, in the color toner mixed in the black toner-containing developer, the positively charged fine particles and the negatively charged fine particles whose surface has been treated on the surface of the color toner by charging with the black toner or the carrier migrate to the black toner or the carrier. On the surface of the color toner, there are almost no positively charged fine particles and negatively charged fine particles. Color toner that has not been surface-treated with positively charged fine particles and negatively charged fine particles is hardly charged even when mixed with a carrier, and such color toner does not strongly attract the carrier, so it scatters from the black developing device. And adheres to the photoreceptor with a Van der Waals force or a mirror image force. Also, 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.
As a result, 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 that a black colorant is used as the colorant, but the binder resin and metal oxide fine particles are positive in the color toner. The same as those described as the charged fine particles or the negatively charged fine particles 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. For 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 appropriately selected according to the purpose of use. A first latent image is formed by irradiation with a laser beam or the like.
Spot development is performed by a first developing device using a component-based magnetic developer. 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 second latent image, and the second latent image is formed using a black toner and an optional carrier. Spot development is performed using a component-based 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 Styrene-acrylic resin 100 (Mw / Mn: 25.8 Mw: 251,400) Carbon black MA # 85 (manufactured by Mitsubishi Kasei Kogyo Co.) Charge control agent Bontron N-013 (Orient Chemical Industry Co., Ltd.) The above materials are put into a Henschel mixer, mixed well, and then melt-kneaded by a twin-screw extruder. After cooling, coarsely pulverized to 3 mm or less, finely pulverized by a jet pulverizer to an average diameter of 13.5 μm, and then classified by a rotary wind classifier to obtain an average
3.1 μm of toner A was obtained.

Next, a hydrophobic silica (R-976:
(Aerosil Co., Ltd.) was subjected to a surface treatment at a ratio of 0.2% by weight to the toner A.

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

Preparation of color toner (toner B ′ to L ′) (red toner)) parts by weight styrene-acrylic resin 100 (Mw / Mn: 21.3, Mw: 184,200, Av: 5.2) Chromophthal Red 2R 4 (manufactured by Ciba Geigy) P-51 (quaternary ammonium salt) 2 (manufactured by Orient Chemical Industries) The above materials were treated in the same manner as for toner A to obtain toner B having an average diameter of 13.2 μm.

Hydrophobic silica R976 (negative charge) (Nippon Aerosil), hydrophobic titania T-805 (positive charge) (Nippon Aerosil), hydrophobic alumina RX-C (positive charge) (Alumina Japan) and hydrophobic aminosilica RA-200H (Aerosil Japan) were subjected to surface treatment with respect to toner B at the ratio shown in Table 1 below.

The toners thus obtained are referred to as toners B ′ to L ′.

Toner M 'to P' parts by weight Styrene-acrylic resin 98 (Mw / Mn: 25.6, Mw: 196,200) Styrene-aminoacrylic resin 5 (Mw / Mn: 6.4, Mw: 62,900, amine value: 178) Copper phthalocyanine 4 The above materials were treated in the same manner as toner A,
13.3 μm of toner M was obtained. The surface of this toner is treated with hydrophobic silica H-2000 (negatively chargeable) (manufactured by Hoechst Japan).
Hydrophobic titania MT-150A (positive chargeability) (manufactured by Teikoku Chemicals)
And surface-treated at the ratios shown in Table 2 below to form toners M ′ to
P 'was prepared.

Toner Q '(ratio) parts by weight Styrene-acrylic resin 90 (Mw / Mn: 25.6, Mw: 196,200) Styrene-aminoacrylic resin 10 (Mw / Mn: 6.4, Mw: 62,900, amine value: 178) Copper phthalocyanine 4 The above materials were treated in the same manner as toner A,
12.8 μm red toner Q was obtained. The surface of this toner is H-20
00 was subjected to a surface treatment at a ratio of 0.2 wt%, and MT-150A was subjected to a surface treatment at a ratio of 0.07 wt%.

The toner thus obtained is referred to as a toner Q '. Toner R '(specific ratio) parts by weight Styrene-acrylic resin 100 (Mw / Mn: 18.9, Mw: 187,600, Av value: 35.6) Chlorinated copper phthalocyanine 4 The above material was treated in the same manner as toner A, and averaged. Diameter
12.8 μm red toner R was obtained. The surface of this toner is H-20
00 was subjected to a surface treatment at a ratio of 0.2 wt%, and MT-150A was subjected to a surface treatment at a ratio of 0.07 wt%.

The toner thus obtained is referred to as a toner R '. Prepared parts by weight of carrier Styrene-acrylic resin 100 (Hymer TB-1000, manufactured by Sanyo Chemical Industries) Magnetic powder RB-BL 250 (magnetite, manufactured by Titanium Industry 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 40 μm to obtain a binder-type microcarrier.

Preparation of Developer Each of the black toner (toner A ') and the color toners (toner B' to toner R ') prepared as described above.
For 10 parts by weight, binder type microcarrier (40μ
m) 90 parts by weight were 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 B to R) was mixed with the above microcarrier at the same weight ratio to prepare a developer, and the charge amount was measured.

 Table 3 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, spot fog and background 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: amorphous silicon photoreceptor, 1st development: magnetic brush method (microtoning method) 2nd development: magnetic brush method (microtoning method) Transfer charger: applied voltage +5.5 kV Main charger: applied voltage +6.5 kV 2 Charger: grid voltage +650 V Using the above apparatus, the transferred image after 20,000 copies was observed with the naked eye, and color fog was evaluated as follows. The results are shown in Table 4.

Effects of the Invention According to the present invention, fog (mixed color fog, spot fog,
Black and color copied images can be obtained without causing background fog or the like.

[Brief description of the drawings]

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

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-294580 (JP, A) JP-A-63-254465 (JP, A) JP-A-61-250658 (JP, A) JP-A-62-294 17751 (JP, A) JP-A-52-123622 (JP, A) JP-A-63-83733 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/097

Claims (1)

(57) [Claims] 1. 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 positively charged photoconductor. The color toner is a positively-chargeable color toner in which negatively-chargeable fine particles and positively-chargeable fine particles are mixed and added on the surface thereof, and the added amounts of the negatively-chargeable fine particles and the positively-chargeable fine particles are different from those of the color toner. The toner is 0.05 to 1% by weight and the triboelectric charge between the color toner to which the fine particles are not added and the carrier used for the black toner-containing developer is +3 μm.
A developer for a printer characterized by being between C / g and -1 μC / g.