JPH0356973A - Binary magnetic developer - Google Patents

Abstract

PURPOSE:To prevent deterioration of development performance and that of fixability and to maintain high image quality by incorporating a colorant, a binder, and as a magnetic material iron or an iron alloy, in the toner. CONSTITUTION:The toner contains at least the colorant, the binder, and as the magnetic material, iron or an iron alloy, such as iron or its alloy powder having a color near metallic whiteness, optionally having a transition metal, such as Ni, Co, or rare earth metals, or other elements, such as Al, V, W, C, P, or B, thus permitting the obtained binary magnetic developer not to stain the inside of a copying machine, to reduce fog without inviting deterioration of developing performance, to maintain high image quality, and to be converted into a color developer.

Description

[Detailed Description of the Invention] Industrial Field of Application] The present invention relates to a two-component developer used in electrophotography, etc., which produces high-quality images without deterioration of developability or deterioration of fixing performance. This invention relates to a two-component magnetic developer that can be maintained.

[Conventional technology]

In the conventional electrophotographic method, US Patent Fi'F 2,297,6
As described in No. 91, No. 2, 357, 809, an electrostatic latent image is formed on the surface of a photoreceptor, the electrostatic latent image is made into a toner image by a dry developer consisting of colored particles, and then After transferring the toner image to a transfer sheet such as paper,
A copy image is formed by permanently fixing the image by applying heat or pressure. On the other hand, after the toner image has been transferred to the photoreceptor, there remains some residual material on the surface of the photoreceptor. After the toner is cleaned by a cleaning member, it is used again for image formation.

As the dry type developer described in tJ, so-called 1M. 2. Description of the Related Art Separate system developers and so-called two-component developers consisting of a non-magnetic toner containing no magnetic material and a magnetic carrier are known. 1
In a component-based developer, positively charged toner and negatively charged toner coexist, and the friction band 'ffiffl is small, so for example, toner adheres to non-image areas on the photoreceptor, resulting in the final fixed image. There are problems in that fogging may occur in the image area on the photoreceptor, or the amount of toner adhering to the image area on the photoreceptor may be insufficient, resulting in a low degree of coverage of the final regular image.

On the other hand, the latter two-component developer is composed of a toner and a carrier, and the carrier has the function of charging the toner to a desired polarity. 1!7 on the charging station! It is possible to create a developer that can impart a triboelectric charge and has much superior triboelectric charging properties compared to the one-component developer described above.

[Problem to be Solved by the Invention J] However, the toner band 'Iffi has a certain distribution, and not all toner has appropriate charging convexities. In conventional two-component developers, toner particles with small electric charges easily separate from carrier particles, and the centrifugal force caused by the rotation of the developing sleeve can cause contamination of various parts inside the copying machine due to so-called flying toner. Moreover, the image quality deteriorated due to the occurrence of force blur. Therefore, in order to prevent the toner from flying off, efforts have been made to develop toner added with a magnetic substance that has a binding force between the toner and the carrier. Reports have been made on toners to which cubic or acicular magnetite is added as a magnetic substance, for example, in JP-A-57-1300509 and JP-A-61-141451. Because the toner has poor dispersibility and becomes uneven, when the toner is frictionally charged with the carrier, oppositely charged toner is generated, and the toner charge decreases to zero, making it impossible to maintain excellent images without fogging for a long time. I couldn't do that.

In addition, as a recent trend among users, there has been a strong desire to make color toner more powerful, but since magnetite itself has a black color, it is not suitable as a magnetic material for colorizing toner. be.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to avoid contamination of the inside of a copying machine due to toner scattering.
It is an object of the present invention to provide a two-component magnetic developer which can maintain high image quality, reduce fog and reduce IB scum due to deterioration in developability, and can also be used for color development.

[Means for Solving the Problems] The above object of the present invention is to provide a two-component magnetic developer comprising a toner and a carrier, wherein the toner contains at least iron or an iron alloy as a colorant, a binder, and a magnetic material. This is achieved by a two-component magnetic developer characterized by the following.

[Function] In the present invention, iron powder or iron alloy is added as a magnetic substance to the toner of the two-component magnetic developer.

Since iron or an iron alloy has a high magnetization strength, only a small amount is required to obtain the desired magnetization strength, and the fixing properties are not deteriorated.

The present invention will be explained in more detail below.

The two-component developing agent of the present invention includes a toner containing colorizable magnetic particles and a carrier. Magnetic particles used in toner include iron powder or iron alloys that are close to metallic white, to which transition metals such as nickel, cobalt, and rare earths, aluminum, vanadium, tungsten, carbon, phosphorus, and boron are added. You may. Since iron powder or iron alloy has a nearly metallic white color, toners can be colored by adding chromatic dyes or pigments. Examples of iron alloys include iron alloys containing one or more nonmetallic elements such as carbon, phosphorus, and boron, or metal elements such as aluminum, nickel, cobalt, titanium, copper, vanadium, manganese, tungsten, and chromium. can be mentioned.

The use of iron or iron alloys as mentioned above has a great effect on image quality and must be taken into consideration, but since iron or iron alloys have a relatively large magnetic force, conventional magnetite etc. It is clear that the effect as a magnetic material can be obtained even in a much smaller amount than when used. That is, according to the present invention, it is preferable to use 5 to 50% by weight based on the total weight of 1 to 50%.

Conventionally known binders can be used in the toner used in the present invention, and examples thereof include styrene-acrylic resin, polyester resin, and epoxy resin.

Other toner components include various additives such as color viewing agents, charge control agents, fluidizing agents, and detergents, which can be used as necessary.

Examples of colorants include carbon black, nigrosine dye (C.I. No. 504153),
Lamp black (C.I. No.77266
), chrome yellow, DuPont oil red, quinoline yellow phthalocyanine blue, malachite green oxalate, etc. can be used.

The amount added is preferably 1 to 20% based on the binder of the toner.

Examples of the charge control agent include nigrosine dyes, metal-containing azo dyes, metal complexes, sulbonamide derivatives of copper phthalocyanine, sulfonic acid or sulfonate derivatives of copper phthalocyanine, and quaternary ammonium compounds. can.

In order to further improve the viscoelasticity of the toner when it is melted,
Alternatively, in order to further improve fixing properties, it is preferable to knead wax with a binder resin. Specifically, solid paraffin, low molecular weight polyolefin such as polyethylene or polypropylene, fatty acid ester, higher alcohol, amide wax, etc. can be used.

Further, the two-component magnetic developer of the present invention includes, for example, silica,
Mixing inorganic fine particles such as alumina, titania, barium titanate, magnesium titanate, canolecium titanate, strontium titanate, zinc oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide, silicon nitride, etc. as external additives. I can do it. In particular, it is preferable to use silica fine particles. Add more toner
In order to be electrically charged, it is preferable to use silica fine particles whose surface has been treated with an amine-modified silicon compound. The addition and mixing ratio of the inorganic fine particles is 0.01 to 5i [1
It is preferably 1%, particularly preferably 0.01 to 2%.

The particle size of the inorganic fine particles is preferably 5 mμ to 2μ.

Further, as a lubricant, for example, zinc stearate, aluminum stearate, lithium stearate, stearic acid, hydrogenated castor oil, and others can be externally added.

The addition and mixing ratio of these lubricants is, for example, 0 for the entire toner.
．． 01 to 2% by weight is preferred.

The average particle diameter of the toner particles is preferably about 5 to 20 μm.

As the carrier, conventionally known carriers can be used, but in order to charge the toner particles, iron, nickel,
Particles of ferromagnetic metals such as cobalt, alloys containing these metals, ferrite, magnetite and other ferromagnetic metal compounds, vinylidene fluoride-tetrafluoroethylene copolymers, tetrafluoroethylene, 2.2.2- Preferably, the material is coated with a fluororesin such as trifluoroethyl methacrylate or pentafluoro-10-propyl methacrylate, or a silicone resin or a vinyl resin such as methyl methacrylate or methyl methacrylate-styrene copolymer.

The average particle diameter of the carrier is preferably 20 to 200 μm, particularly preferably 30 to 150 μm.

To give an example of a preferred method for manufacturing the two-component magnetic developer of the present invention, first, the material resin of the binder resin and magnetic particles are melt-kneaded, the mixed material is crushed and classified, and a toner of a desired particle size is produced. get. The toner particles may contain toner components as described above. Thereafter, it can be mixed with a carrier to obtain a two-component magnetic developer.

In addition, when toner components such as colorants, release agents, and other property improving agents are dispersed and contained in toner particles, they are uniformly mixed in advance using an extruder, etc., and then crushed and classified into the desired amount by pulverization and classification. The powder may have a particle size of . Further, external additives such as inorganic fine particles and lubricants are added and mixed after pulverization and classification.

[Examples] Hereinafter, the present invention will be specifically explained using Examples, but the present invention is not limited thereto.

Example 1 60% by weight of polyester resin, 31% by weight of iron powder, 5% by weight of Rikiichi Bomb Black, and 4% by weight of fatty acid ester wax and acid amide wax were melt-kneaded. The toner particles were then mechanically crushed and classified to obtain toner particles.

Certain carrier particles were obtained from 98% by weight ferrite coated with 2% by weight methyl methacrylate-styrene copolymer. A two-component magnetic developer was prepared by mixing 95% of the carrier particles and 5% of the obtained toner particles.

The obtained sample was mounted on a copying machine nu-Bix5070 (manufactured by Konica), and a photocopying test was conducted 300,000 times.

The resulting image was of high quality, with no fogging and even fine lines were clearly reproduced, even after 300,000 copies. Further, the amount of charge remained almost constant without decreasing until after 300,000 copies were made. No toner scattering was observed inside the copying machine.

Example 2 Using J3 in Example 1, the binder resin of the toner was changed to methyl methacrylate-styrene copolymer, and first, the addition range of iron powder was changed appropriately within the range of O to 75% by weight to correspond to the above. The amount of binder resin added to the toner is v4.
A sample of a bipartite magnetic developer was obtained using fS. At this time, by changing the composition ratio of methyl methacrylic acid and styrene, toners with different charge numbers were created.

Each of the obtained samples was loaded into a copying machine U-Bix5070 (manufactured by Konica), and a photocopying test was conducted 300,000 times. However, if the image became unclear and unsuitable for practical use due to fogging or the like during the test, the live-action test 1- was discontinued at that point.

In the above live-action test, the measurements described in (■) were performed.

■Image @density Using "Sakura Densitometer" (manufactured by Konica),
The relative density of the white background portion with the original tS degree of 0.0 with respect to the copied image was measured and defined as the image density.

■Using the fogging “Sakura Densitometer” (manufactured by Konica),
The determination was made by measuring the relative ay1 with respect to the copy image of the white background portion where the original I1 degree is 0.0. In addition, the white background reflection intensity is 0.0.
And so.

■Image quality Copy images, image unevenness, nail sharpness, image missing (transfer missing)
Judgment was made visually from three viewpoints.

■While toner scattering was suspended, the area around the developing device and inside the copying machine were visually observed.

The results are shown in Table 1.

In order to obtain a practical image shown in Table 1, it is necessary that Q max be 1.2 or more and fog be 0.01 or less.

As is clear from Table 1, in order to satisfy this requirement, it was found that the iron powder content is preferably 5 to 50 ffi1%.

Example 3 Polyester resin used in Example 1 60% by weight, Fe
-Si-A/! Alloy 32% by weight, copper lid cyanine 4@
A fatty acid ester wax and an acid amide wax were melt-kneaded together in four hangings, and then mechanically crushed and classified to obtain toner particles.

5% by weight of these toner particles and 95% by weight of the same carrier particles as in Example 1 were mixed. A two-component magnetic developer was created.

Comparative Example 1 A bipartite magnetic developer was obtained in the same manner as in Example 3, except that cubic magnetite was used instead of the iron-containing magnetic material.

Copies of the obtained samples of Examples and Comparative Examples were made.
Installed on Six 5070 (manufactured by Nika), 300
,000 live-action tests] I did one. Furthermore, O l-I
A live-action test was also conducted by P.

The image obtained in Example 3 had high quality and was clearly reproduced up to the IIll line without fogging even after 300,000 copies. Further, the charging fear remained almost constant without decreasing until after 300,000 copies were made, the fixing performance was good, and no toner scattering inside the copying machine was observed.

In addition, a high-quality color image with good color saturation was obtained as an OHP image. The transmittance at this time was 60%.

In comparison, in Comparative Example 1, the black was so strong that a color image could not be obtained, and after copying ioo and ooo times, fogging occurred and the image quality deteriorated. Additionally, the O I-I P images lacked transparency. The transmittance at this time was 5%.

[Effects of the Invention] As described above in detail, the present invention has provided a two-component magnetic developer that does not cause deterioration in developability or deterioration in fixability and can maintain high quality color images.

Claims (1)

[Claims] A two-component magnetic developer comprising a toner and a carrier, wherein the toner contains at least a colorant, a binder, and iron or an iron alloy as a magnetic material.