JP2769853B2 - Magenta developer for full color electrophotography - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magenta developer for full-color electrophotography, comprising a ferrite carrier, a fixing resin, and a toner containing a colorant, used for full-color electrophotography.

2. Description of the Related Art As a method for forming a visible image by developing an electric latent image with a toner, an electrostatic printing method, an electrophotographic method, and the like are conventionally known. For example, in electrophotography, U.S. Pat.
297,691 specification, JP-B-42-23910, JP-B-43-24
Various systems described in, for example, Japanese Patent Publication No. 748 are well known. In general, a photoconductive substance is used to form an electric latent image on a photoconductor showing photoconductivity by various means, and then the latent image is developed with toner to obtain a visible image. Then, a powder image is transferred onto paper or the like, and then fixed by heating, pressing, or solvent vapor to obtain a visible image. In order to obtain a multicolor image of color, the original is exposed using a color separation filter, and the above process is repeated a plurality of times using color toners such as yellow, magenta, and cyan, and the toner images are superimposed into color images. Things.

In the development of the electrostatic latent image, the toner is mixed with a carrier having relatively large particles and used as a developer for electrophotography. The composition of both the toner and the carrier are chosen such that the toner has a polarity opposite to the charge on the photoconductive layer due to mutual contact friction. As a result of the contact friction between the two, the carrier electrostatically adheres the toner to the surface, transports the developer as a developer in the developing device, and supplies the toner on the photoconductive layer.

There are many known methods for developing a developer. Cascade developing method described in U.S. Pat.No. 2,618,552, magnetic brush method described in U.S. Pat.No. 2,874,063, U.S. Pat.
JP-A-62-63970 discloses a touch-down method described in JP-A-62-63970 and a developing method in which a bias electric field composed of an AC component and a DC component is applied between a developer carrier (developing sleeve) and a photoconductive layer. There is a so-called J / B development method.

The above-described two-component developer, particularly a full-color developer, is required to satisfy the following conditions. That is, 1). Good spectral reflection characteristics; 2). Excellent stability to light, that is, good light fastness of the copy; 3). Matches the functions required by the copier and does not cause significant side effects, for example, no adhesion to the fixing roller surface and no dyeing. In addition, for color copy images, 1). Excellent continuous gradation 2). It is particularly required that there is no image deterioration even after continuous copying of many sheets, and 3) there is no change in density or the like due to environmental changes.

In a conventional full-color developer, particularly a magenta developer, examples of colorants include quinacridone pigments, thioindigo pigments, xanthene dyes, anthraquinone dyes, and azo dyes.

For example, JP-B-49-46951 discloses a 2,9-dimethylquinacridone pigment, JP-A-55-26574 discloses a thioindigo pigment, and JP-A-59-57256 discloses a xanthene dye. There is a description about. In addition, Tokuno Sho 55
JP-A-42383 describes an anthraquinone dye.

[Problems to be Solved by the Invention] However, none of the colorants is a colorant that satisfies all of the above-mentioned characteristics, and all of them have advantages and disadvantages. For this reason, it is very difficult to rely on a single dye or pigment as the magenta colorant, and it is practical to use two or more colorants in combination to compensate for the disadvantages of each colorant.

For example, the present applicants have proposed a magenta toner using two types of oil-soluble dyes as disclosed in JP-A-57-130044 and JP-A-57-130046. This magenta toner has a vivid color tone and excellent saturation, but on the other hand, one of the dyes contains a component that contaminates the silicone rubber used in the heat roller fixing device, so it is gradually fixed by continuous copying. The silicone roller is dyed, and finally, a so-called offset phenomenon in which the toner is fused to the heating roller is caused. Also, the combination of these oil-soluble dyes is effective in reducing the toner charge rather than increasing it. Therefore, it is possible to sufficiently prevent charge-up under low temperature and low humidity, and it is possible to guarantee a preferable image density. However, conversely, toner scattering due to insufficient charging under high temperature and high humidity, resulting in contamination inside the machine,
Further, fog is caused by the low-charged toner, and image stains are easily generated.

In addition, the magenta toner using the pigment described above has a slow charging rise, and when an image having a larger image area than a black-and-white copy image such as a full-color copy image is copied, the toner supply amount increases, and as a result, the toner is sufficiently charged. There is a problem that unformed toner is generated and fog and scattering are deteriorated. This problem was further exacerbated under high humidity.

In addition, iron carriers and ferrite carriers are generally put into practical use. Here, when compared with black-and-white copying, full-color copying requires much better continuous gradation, but conventional carriers do not fully satisfy this requirement even after copying many sheets. Was.

An object of the present invention is to provide a full-color magenta developer which solves the above-mentioned disadvantages.

That is, an object of the present invention is to provide a magenta developer which can obtain a very vivid magenta color, which is unprecedented, has a large coloring power, and is excellent in light resistance.

Another object of the present invention is to provide a magenta developer which does not cause scattering and fogging even when a color original having a large image area is continuously copied.

Another object of the present invention is to provide a magenta developer which does not deteriorate in scattering and fog even under high humidity.

[Means and Actions for Solving the Problems] That is, the present invention is a magenta developer for full-color electrophotography having at least carrier particles and a magenta toner, wherein the magenta toner is at least a binder resin, It contains a quinacridone colorant and a xanthene dye, and the content ratio of the quinacridone colorant to the xanthene dye is 3 to 20 parts by weight based on 100 parts by weight of the quinacridone colorant. The carrier particles are those having a ferrite surface coated with styrene-acrylic acid-ethylhexyl or styrene-acrylic acid-ethylhexyl-methyl methacrylate, having an average particle diameter of 20 to 60 μm, and a 350 mesh pass. Fine powder amount is 30% by weight or less, 400 mesh pass ultra fine powder amount is 2
0 wt% or less, 250 mesh-on coarse powder amount is 10 wt% or less, saturation magnetization for applied magnetic field of 3,000 Oe is 55 to 75 emu / g, remanent magnetization is 10 emu / g or less, coercivity is The present invention relates to a magenta developer for full-color electrophotography, which is not more than 10e.

The quinacridone colorant, which is a colorant for a magenta toner used in the present invention, is a high-grade colorant having a slightly reddish tint, and excellent in light resistance and charge stability. Has suitable performance. That is, with respect to the hue, the bluish portion has less reflection than the ideal magenta color and is reddish. The color tone also has disadvantages such as poor chroma and insufficient vividness, and therefore, when used alone, the quality of color reproducibility is insufficient. However, when the toner is used as a toner, it has favorable characteristics such as that there is little spent on the carrier surface even after repeated copying.

On the other hand, the xanthene-based dye is a so-called rhodamine-based dye, and is a colorant that emits fluorescence and exhibits a clear bluish pink color. This dye also cannot be used as a magenta color when used alone, but a clear color is obtained,
Or, it has features such as a large coloring power. But,
Since it has a disadvantage of poor light fastness and fading in a short time, the amount of addition cannot be increased. This feature of rhodamine-based dyes must be fully considered since recent full-color copies are used for various applications and light fastness is a very important item.

That is, the reason why the quinacridone and the xanthene-based colorant are used in combination in the present invention is to solve the drawbacks of the quinacridone-based colorant, i.e., the hue and sharpness, by using the xanthene-based colorant which is very excellent in that point. . As a result, it is possible to obtain a toner which has excellent light fastness, has a clear magenta color unlike the related art, and does not deteriorate even by repeated copying on a large number of sheets.

The addition amount of the colorant of the present invention is determined by the type of the binder resin, the presence or absence of the additive used as needed, and the toner production method including the dispersion method, and is not limited uniquely. However, generally speaking, the total amount of the colorant is 2 to 20 parts by weight based on 100 parts by weight of the binder resin, and preferably 3 to 20 parts by weight.
15 parts by weight. The content ratio of the quinacridone colorant to the xanthene dye in the magenta toner is 3 to 20 parts by weight of the xanthene dye based on 100 parts by weight of the quinacridone colorant.

When the content of the xanthene-based colorant exceeds 20 parts by weight,
Light resistance is deteriorated, and the charge amount is also reduced, which promotes scattering and fogging. If the amount is less than 3 parts by weight, the hue and the sharpness deteriorate.

The following compounds are typical examples of the quinacridone colorants.

Among them, CI Pigment Red 122 is particularly suitable as a magenta colorant.

 A typical example of a xanthene-based colorant is C.I.Basic Violet 10 C.I.Basic Violet 11: 1 C.I.Solvent Red 49.

These all have a clear blueish pink color. Since CIBasic Violet 10 and CIBasic Violet 11: 1 are basic dyes, they have some hygroscopicity, and in consideration of compatibility with resins, in the present invention, they are oil-soluble and not compatible with resins. Excellent CISolv with great coloring power
ent Red 49 is particularly suitable.

By using the above-mentioned coloring agent, the hue, the light fastness and the non-dyeability of the roller can be sufficiently satisfied, and a very clear magenta toner can be obtained. However, when the carrier used in the conventional magenta developer is applied to the magenta toner of the present invention, the toner and the carrier are not immediately charged even if rubbed, so that a large number of full-color images having a large image area are copied. When the replenishment amount is large, the replenished toner is developed without being sufficiently charged, and the image quality is remarkably deteriorated due to scattering and fogging. Further, since the charge amount is lower than that of the toners of other colors, scattering and fog increase particularly under high humidity.

The above problems can be solved by using the next carrier. That is, the carrier used in the present invention is characterized by having a smaller average particle size and a sharper particle size distribution than conventional general carriers.
Due to the small particle size, the number of times of contact between the carrier and the toner increases, the rise of the toner charge becomes faster, and even if the replenishment amount increases, the uncharged toner will not be developed. Further, since the rise of the charging speed is increased, it is possible to prevent the scattering and the fog due to the uncharged toner under the high humidity from increasing. Therefore, when combined with the above-described magenta toner, a magenta developer that is extremely vivid magenta, has excellent light fastness, and is resistant to humidity that does not cause scattering or fogging even when a color original having a large image area is continuously copied. Is obtained.

Also, by sharpening the particle size distribution, it solves the phenomenon that the fine powder carrier adheres to the photoreceptor along with the toner during development, which occurs gently with the small particle size carrier, and the poor charging due to the coarse powder carrier To prevent the image quality from deteriorating.

The ultrafine powder of 400 mesh pass is 20% by weight or less, preferably 16% by weight or less. If the amount exceeds 20% by weight, the carrier adheres to the photoreceptor, and smooth frictional charging with the toner is hindered to promote the edge effect. The fineness of the 350 mesh pass is 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less. If it exceeds 30% by weight, the rise of the toner charge becomes extremely poor, and the edge effect also increases.

Further, the amount of coarse powder of 250 mesh on is closely correlated with the sharpness of the image. If it exceeds 10% by weight, the scattering of the toner to the non-image portion increases, and the resolution of the image decreases and the roughness becomes rough. It is easy to occur. Therefore, the amount of coarse powder of 250 mesh on is 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less.

The average particle size of the carrier is preferably from 20 to 60 μm, and more preferably from 30 to 56 μm. When the average particle diameter is less than 20 μm, the image density decreases due to the charge-up of the toner and the carrier adheres to the photoreceptor, and the average particle diameter exceeding 60 μm deteriorates the fine line reproducibility of color copying.

The magnetic properties of the carrier greatly affect the developing properties and transport of the developer. Particularly in color copying, importance is placed on the uniformity and gradation of the image as described above.

If the saturation magnetization exceeds 75 emu / g (for an applied magnetic field of 3000 Oersted), during development, a brush-like brush composed of carrier and toner on the developing sleeve facing the electrostatic latent image on the photoreceptor The ears are firmly tightened, and the gradation and the reproduction of halftone are deteriorated. On the other hand, when it is less than 55 emu / g, it is difficult to hold the toner and the carrier on the developing sleeve, and there is a disadvantage that fog and toner scattering are deteriorated. Further, when the residual magnetization and the coercive force of the carrier are too high, the transport of the developer in the developing machine is deteriorated, and image blurring and uneven density in a solid image are liable to occur. Therefore, the residual magnetization and the coercive force were each set to 10 emu /
g or less, 10 e or less (for an applied magnetic field of 3,000 Oe), preferably 5 emu / g or less and 6.0 e or less.

As the binder resin to be applied to the toner of the present invention, all known resins can be used. For example, polystyrene, poly-p-chlorostyrene, a homopolymer of styrene such as polyvinyltoluene and a substituted product thereof, styrene-P- Chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethacrylic acid Methyl copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Styrene-based copolymers such as polymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, styrene-maleic acid ester copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, and polyacetic acid Vinyl, poly Tylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyamide, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, Chlorinated paraffin, paraffin wax or the like can be used alone or as a mixture.

The inventors of the present invention have conducted intensive studies on these binder resins. As a result, the use of a polyester or a copolymer of styrene-acrylate to improve the fixability and improve the electrophotographic properties of the toner. Further, the present inventors have found that one of these two resins is mainly used, a quinacridone-based colorant is dispersed, and a xanthene-based dye is further added to another resin, particularly a phenol resin. Mix with the dispersed one,
It has been found that by combining them by kneading or the like, it is possible to further improve the electrophotographic characteristics and characteristics such as hue, saturation, and freshness desired as a color toner.

Further, a charge control agent may be added to the toner of the present invention as needed. For example, in the case of a negative toner, a dye having an anthraquinone-based magenta color, or a metal chelate and a salt of alkyl salicylic acid, and in the case of a positive toner, a basic dye of magenta color, or a dye thereof. Lake pigments or quaternary ammonium salts can be used.

Further, for the developer in which the toner of the present invention is used,
It is preferable to add a charge control agent such as colloidal silica or a fluidity modifier to the toner in an amount of about 0.01 to 5% by weight (preferably 0.1 to 2% by weight).

As the carrier used in the present invention, known materials can be used without departing from the scope of the present invention. For example, surface-oxidized or unoxidized iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth, and the like And their alloys or oxides and ferrites. Preferably, ferrites selected from zinc, copper, nickel and cobalt metals can be used. There is no particular restriction on the manufacturing method.

It is also possible to coat the surface of the carrier with a resin or the like. As the method, any conventionally known method such as a method of dissolving or suspending a coating material such as a resin in a solvent, coating and adhering to a carrier, and a method of simply mixing with a powder can be applied.

The fixing substance on the carrier surface varies depending on the toner material, for example, polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal complex of ditersharry butylsalicylic acid, styrene resin,
Acrylic resin, polyamide, polyvinyl butyral,
It is appropriate to use nigrosine, amino acrylate resin, basic dyes and lakes thereof, fine silica powder, fine alumina powder or the like alone or in combination, but it is not necessarily limited thereto.

The amount of the compound to be treated may be appropriately determined so that the carrier satisfies the above conditions, but is generally desirably 0.1 to 30% by weight (preferably 0.5 to 20% by weight) based on the carrier of the present invention.

In the present invention, a particularly preferred embodiment is Cu-Zn-
A coated ferrite carrier which is a ternary ferrite of Fe and whose surface is coated with the following specific resin can be preferably used. As a result of intensive studies by the present inventors,
When the following specific styrenic copolymer is used, it is 0.01 to 5% by weight, preferably 0.1 to 1% by weight based on the carrier.
The coated coated ferrite carrier was particularly good. Examples of the styrene-based copolymer include styrene-2-ethylhexyl acrylate (20:80 to 80:20) and styrene-2-ethylhexyl acrylate-methyl methacrylate (20 to 60: 5 to 30:10 to 50). Used.

The method for measuring the particle size distribution of the carrier in the present invention is as follows.

1. Measure about 100 g of the sample to the nearest 0.1 g.

2. Use standard sieves of 100 Mesh to 400 Mesh (hereinafter referred to as sieves), stack them in the order of 100, 145, 200, 250, 350, 400 from the top, place a saucer on the bottom, put the sample in the top sieve and cover it.

3. This is shaken by a vibrator at a horizontal rotation of 285 ± 6 times per minute and a vibration frequency of 150 ± 10 times per minute for 15 minutes.

4. After sieving, measure the iron powder in each sieve and tray to the nearest 0.1 g.

5. Calculate to the second decimal place by weight percentage and round to the first decimal place according to JIS-Z8401.

However, the size of the sieve frame is 200 mm inside diameter above the sieve surface,
The depth from the top surface to the sieve surface is 45mm.

The sum of the weights of iron powder in each part shall not be less than 99% of the mass of the starting sample.

The average particle size is determined from the above measured particle size distribution according to the following equation.

The BHU-60 is used to measure the magnetic properties of carriers.
Type magnetization measurement device (manufactured by RIKEN) is used.

About 1.0 g of a measurement sample is weighed, packed in a cell having an inner diameter of 7 mmφ and a height of 10 mm, and set in the above-mentioned apparatus.

In the measurement, first, an applied magnetic field is gradually applied to change up to 3,000 Oe. Next, the applied magnetic field is reduced, and finally a hysteresis curve of the sample is obtained on the recording paper. From this, the saturation magnetization, residual magnetization, and coercive force are obtained.

[Examples] Hereinafter, the present invention will be described in detail with reference to Examples.

In Table 1, carriers (1) and (2) were prepared.

Each toner was melt-kneaded with a roll mill, cooled, then finely pulverized and classified with a jet mill, and the average particle diameter was 7%.
９9 μm was obtained. 0.5% by weight of hydrophobic silica (trade name: Taranox 500 Talc) and
0.2% by weight of alumina fine powder (aluminum oxide C) was externally added with a Henschel mixer to obtain the toner of the present invention. Further, the toner and the carrier were mixed to obtain a developer having a toner concentration of 4.5%. Using this developer, a copy test was performed using a color electrophotographic apparatus full-color copying machine (manufactured by Canon) having an OPC photosensitive drum shown in FIG.

Using a developer having the above formulation and a manuscript having an image area of about 40%, a printing durability test of 20,000 sheets was performed. Even after copying 20,000 sheets,
An image with a small edge effect was obtained, and no image deterioration such as fogging or scattering and no contamination of the silicone rubber roller occurred. The color tone of the obtained copy is a vivid magenta color and has a sufficient color saturation. To check the light resistance of the copy, use a fade meter (trade name: Super Fade Meter: manufactured by Suga Test Instruments Co., Ltd.)
A forced irradiation test of hr was carried out, but it was found that there was no change at 40 hr, and that the light resistance was practically no problem.

In addition, a similar printing test was conducted at 30 ° C, 80% high temperature and high humidity.
Although 100,000 sheets were printed, no scattering or fogging occurred.

Printing was performed in the same manner as in Example 1, but the image, color, and light resistance were sufficiently satisfactory.

Printing was performed in the same manner as in Example 1. However, although no image deterioration was observed, the hue of the color shifted to the red side, the saturation was poor, the color became very dull, and a clear magenta color was obtained. Could not be obtained.

Using a developer having the above formulation and a manuscript having an image area of 40%, a printing durability test of 10,000 sheets was performed. A sharp and excellent gradation image was obtained even after copying 10,000 sheets, and no image deterioration such as fogging and scattering and contamination of the silicone rubber roller occurred. The color tone of the obtained copy is a vivid magenta color and has a sufficient color saturation. In order to check the light resistance, use a fade meter (trade name: Super Fade Meter: manufactured by Suga Test Instruments Co., Ltd.) for 60 hours.
, But no change at 40hr
Lightfastness was found to be practically acceptable.

In addition, a similar printing test was conducted at 30 ° C, 80% high temperature and high humidity.
Although 5,000 sheets were printed, no scattering or fogging occurred.

Printing was carried out in the same manner as in Example 1. However, although there was no problem in color and light fastness, fog and scattering in the machine occurred on 15,000 sheets. Further, the carrier was spent by toner during the running, and the triboelectric charging ability was reduced.

Further, in the same manner as in Example 1, a printing durability test was conducted on 50,000 sheets at a high temperature and high humidity of 30 ° C. and 80%, and fog and scattering were remarkably deteriorated on 1,000 sheets.

[Effects of the Invention] As described above, by using the developer obtained according to the present invention, scattering and fogging do not occur even when continuous copying of a color original having a large image area is performed, and even under high humidity. A good image is obtained, light resistance is improved, and a very clear magenta color can be obtained, indicating that the present invention is industrially very useful.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a color electrophotographic copying machine to which the color toner of the present invention is applied. DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... Rotary developing device 3 ... Supply hopper 4, ... Supply cable 5 ... Transfer drum, 6 ... Cleaner 7 ... Fixing device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-9466 (JP, A) JP-A-63-301960 (JP, A) JP-A-62-297857 (JP, A) JP-A-61-297 148457 (JP, A) JP-B 61-18234 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/09 G03G 9/107

Claims (1)

(57) [Claims] 1. A magenta developer for full-color electrophotography having at least carrier particles and a magenta toner, wherein the magenta toner contains at least a binder resin, a quinacridone-based colorant and a xanthene-based dye. The ratio of the content of the xanthene dye to the content of the xanthene dye is 3 to 20 parts by weight based on 100 parts by weight of the quinacridone colorant, and the carrier particles are styrene-acrylic acid- The ferrite surface is coated with ethylhexyl or styrene-acrylic acid-ethylhexyl-methyl methacrylate, the average particle size is 20 to 60 μm, the amount of fine powder in a 350 mesh pass is 30% by weight or less, and the ultra fine powder in a 400 mesh pass. Quantity 2
0 wt% or less, 250 mesh-on coarse powder amount is 10 wt% or less, saturation magnetization to applied magnetic field of 3,000 Oe is 55 to 75 emu / g, residual magnetization is 10 emu / g or less, coercive force is A magenta developer for full-color electrophotography, wherein the developer is 10 e or less.