JPH04175770A - Color developer - Google Patents

Abstract

PURPOSE:To stabilize the electrification property in various environments and obtain a high-quality image by containing a color toner and a carrier having a specific additional component in coat resin. CONSTITUTION:An insulating nonmagnetic color toner and a carrier with the average grain size 10-200mum coated with electrically insulating resin 0.1-5.0wt.% against the carrier core material weight are contained. A nitrogen-containing compound 0.3-15wt.% is contained against the whole coating resin, this organic resin containing at least fluoroalkyl acrylic polymer is coated on the carrier core material to obtain a carrier. A general compound such as a compound with an amine structure or a compound with a pyridine ring structure can be used for the nitrogen-containing compound, and the compound with an amine structure is preferable in particular. The friction electrification characteristic is stable, and carrier sticking can be excellently prevented.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a developer used for developing an electrical latent image or a magnetic latent image in electrophotography or electrostatic printing, and particularly relates to a developer used for developing an electric latent image or a magnetic latent image in electrophotography or electrostatic printing. This invention relates to a color developer that has significantly improved image quality.

[Prior Art] Conventional methods for developing electrostatic latent images using toner in electrophotography can be roughly divided into two methods: methods using a so-called two-component developer in which a small amount of toner is dispersed in a medium called a carrier; There is a method in which a so-called one-component developer is used without using toner. The present invention relates to a two-component developer comprising a toner and a carrier among the above-mentioned developers. The carriers constituting the two-component developer are roughly divided into conductive carriers and insulating carriers, and oxidized or unoxidized iron powder is usually used as the conductive carrier.
A developer containing this iron powder carrier has the disadvantage that the triboelectric charging property of the toner is unstable and that fog occurs in the visible image formed by the developer. That is, as the developer is used, toner particles adhere and accumulate on the surface of the iron powder carrier particles (spent toner), so the electrical resistance of the carrier particles increases and the bias current decreases.
Moreover, the triboelectric charging properties become unstable, and as a result, the image density of the visible image formed decreases and fog increases. Therefore, if a developer containing iron powder carrier is used for continuous copying with an electronic copying device, the developer deteriorates after a few times, making it necessary to replace the developer early, resulting in high costs. Become something.

Further, typical insulating carriers are carriers in which the surface of a carrier core material made of a ferromagnetic material such as iron, niragel, ferrite, etc. is uniformly coated with an insulating resin. In developers using this carrier, toner particles are less likely to fuse to the carrier surface than in the case of conductive carriers, and at the same time, it is easy to control the frictional charging between the toner and the carrier, resulting in increased durability. It has the advantage of being particularly suitable for high-speed electronic copying machines because of its excellent performance and long service life.

However, in this insulating carrier, the carrier itself is strongly charged with a polarity opposite to that of the toner particles.
This not only causes the problem of carrier adhesion to the background area, but also increases the amount of toner spent on the carrier surface.

This tendency is noticeable in non-magnetic color toners that do not have leakage sites in themselves, and is particularly pronounced when colorant-containing resin particles using a polyester binder with high charging ability is used as a toner. This becomes a problem below.

As a countermeasure for this problem, on the carrier side, it has been proposed to coat the carrier with conductive carbon black, etc., dispersed in the coating resin, in order to eliminate the carrier adhesion that occurs because the carrier itself is strongly charged. However, it cannot be said that a stable coating state has been achieved so far, and new problems such as fogging due to release of carbon black and the like due to long-term use have arisen.

Furthermore, examples have been proposed in which carriers are coated with fluororesin or silicone resin, etc., which have low surface energy, but carriers coated with resins with low surface energy charge the toner slowly, and are particularly difficult to charge toner under high humidity. It is easy to cause scattering, and there is currently no satisfactory carrier.

[Problems to be Solved by the Invention] The present invention provides a developer that does not have the above drawbacks, and provides a color developer that has stable triboelectric charging characteristics and is excellent in preventing carrier adhesion. be.

Another object is to provide a color developer with less toner scattering.

Another object of the present invention is to provide a long-life color developer which has a stable developing ability by preventing toner spending from occurring on the surface of carrier particles (and by firmly adhering the carrier coating resin).

Another object of the present invention is to provide a color developer that exhibits good charging start-up and small fluctuations in charging characteristics (i.e., provides extremely stable images) in response to environmental changes.

[Means and effects for solving the problems] The present invention is characterized in that a small amount of electrically insulating material (both 0.1 to 5.0% by weight based on the weight of the insulating non-magnetic color toner and the carrier core material) A color developer comprising a carrier coated with a resin and having a weight average particle diameter of 10 to 200 μm, wherein the carrier is a resin that completely coats a nitrogen-containing compound in an organic resin containing at least a fluorinated alkyl acrylic polymer. A color developer is characterized in that it is a carrier in which a carrier core material is coated with a resin containing 0.3 to 15% by weight based on the color developer.

Until now, as an example of using a compound containing a nitrogen atom as a coating material for a carrier, for example,
No. 124345, etc., proposes an example of a compound having an amine structure containing a tertiary amine as a charge control agent.

However, with the above carrier configuration, when the non-magnetic color toner of the present invention is combined with an insulating non-magnetic color toner that does not have a conductive member such as magnetic powder or carbon black, although the initial characteristics are certainly good, the long-term It has been found that the initial level cannot always be maintained during continuous copying over a long period of time, resulting in problems such as a decrease in image density and deterioration of fog.

Furthermore, an example of containing N-vinylcarbazoles has been proposed in JP-A-59-124346, etc.
The above example is just a carrier for positively chargeable toner, and is completely different from the present invention.

In addition, attaching a quaternary ammonium salt as a compound having an ammonium salt structure to the carrier surface has been disclosed, for example, in Japanese Patent Application Laid-Open No. 62-229256, but the above proposal does not involve incorporating it into the resin, but is based on the present invention. The invention stopped (it is different).

Furthermore, the use of fluorinated alkyl acrylic polymers as coating materials for carriers was disclosed in Japanese Patent Application Laid-Open No. 61-80.
These fluorinated alkyl acrylic polymers have significant advantages such as adhesion to the core material, as disclosed in Japanese Patent Application Laid-open No. 163 and Japanese Patent Application Laid-Open No. 62-39881. However, changes in the amount of charge due to environmental differences, especially changes in humidity, are quite large, and with high humidity, when an original document with a high image area ratio is continuously copied, sufficient charge is not applied and toner scatters, resulting in unsatisfactory results. It's not something I can do.

The reason why a carrier made of a fluorinated alkyl acrylic polymer coated with a nitrogen atom-containing compound is extremely effective in stabilizing charging is because the fluororesin, which has a small surface energy, is slow in imparting a charge to toner. This is because the compounds have a complementary structure. Furthermore, it has been found that a carrier containing an ammonium salt also plays a role in lowering the absolute value of triboelectricity under low humidity.

The reason for this is not yet clear, but it is presumed that the nitrogen compound contained in the present invention creates leak sites in response to the phenomenon of toner charge-up.

In the present invention, in order to make the above-mentioned charging rise function and leakage function sufficiently effective, the nitrogen-containing compound must have 3 to 30 carbon atoms, preferably 6 to 24 carbon atoms per nitrogen atom. It is necessary to contain

If the number of carbon atoms is less than 3, the moisture resistance properties, especially under high temperature and high humidity conditions, will deteriorate, and problems such as toner scattering due to triboelectric deterioration will occur.

In addition, if the number of carbon atoms is more than 30, the characteristics under high temperature and high humidity will improve, and the charging start-up will also be good, but the leakage function will decrease, and as a result, image density will decrease due to increased triboelectric charge under low temperature and low temperature. A problem will occur.

As the nitrogen-containing compound used in the present invention, general compounds such as a compound having an amine structure and a compound having a pyridine ring structure can be used.

A particularly preferred compound for the present invention is a compound having an amine structure, and is represented by the following formula I.

Specific examples of nitrogen-containing compounds that can be used in the present invention are shown below.

(The following are blank spaces) <Example ■><Example■><Example M) Example V> The monomers for the fluorinated alkyl acrylic polymer, which is the carrier coating resin of the present invention, include the following.

That is, 1,1-dihydroperfluoroethyl, 1,1-dihydroperfluoropropyl, 1,1-dihydroperfluorohexyl, 1,1-of acrylic acid or methacrylic acid.
Dihydroperfluorooctyl, 1,1-dihydroperfluorodecyl, 1,1-dihydroperfluorolauryl, 1
．． 1,2.2-tetrahydroperfluorobutyl, 1,1
．． ．． 2.2-tetrahydroperfluorohexyl, 1,1
．． ．． 2.2-tetrahydroperfluorooctyl, 1,1
．． ．． 2.2-tetrahydroperfluorodecyl, 1,1,
2.2-Tetrahydroperfluorolauryl, 1,1,2
．． 2-tetrahydroperfluorostearyl, 2,2,3
．． 3-tetrafluoropropyl, 2,2,3,3,4.4
-hexafluorobutyl, 1,1. ω-trihydroperfluorohexyl, 1. l, ω-trihydroperfluorooctyl, 1,1,1,3,3.3-hexafluoro-2-fluorovir, 3-perfluorononyl-2-acetylpropyl, 3-perfluorolauryl-2-acetylpropyl,
Examples include various ester compounds such as.

Other suitable resin component monomers to be copolymerized with the above fluorinated alkyl acrylic monomer include the following. That is, alkylstyrenes such as styrene, methylstyrene, dimethylstyrene, trimedelstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene, fluorostyrene, chlorostyrene, Halogenated styrenes such as bromostyrene, dipromostyrene, and iodostyrene, as well as nitrostyrene, acetylpropyl,
Styrenic monomers such as methylstyrene; acrylic acid, methacrylic acid, α-ethyl acrylic acid, crotonic acid,
Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as α-methylcrotonic acid, a-ethylcrotonic acid, incrotonic acid, tiglic acid, ungellic acid, maleic acid, fumaric acid,
Examples include addition-polymerizable unsaturated aliphatic dicarboxylic acids such as itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, and dihydromuconic acid.

The carrier coating polymer only needs to contain a fluorinated alkyl acrylic polymer.

In the present invention, all general materials such as iron powder and ferrite powder can be used as the carrier core material.

The coating amount of the coating resin according to the present invention to the carrier core material is such that the resin solid content is 0.1 wt% to 30 wt%, preferably 0.2 wt% to 10 wt%. 0.1. wt
If the amount is less than 30 wt %, the coating effect of the resin on the carrier core material will not be sufficient, and if the coating amount exceeds 30 wt %, it is meaningless, and from the viewpoint of manufacturing, an excessive amount of resin may be present alone, which is not preferable.

In the present invention, all common carrier core materials such as iron powder and ferrite powder can be used, and this is also one of the major features of using resin. Also,
The particle size of the carrier core material used is 10 to 200 μm, preferably 20 to 65 μm.

In particular, the material of the magnetic particles used in the present invention is 9
8% or more Cu-Zn-Fe (metal composition ratio (5-20)
Ferrite particles having a composition of: (5 to 20) : (30 to 80) are preferable because the surface can be easily made uniform and the charging ability is stable.

Binding substances used in the colorant-containing resin particles used in the present invention include polystyrene, poly-p-chlorostyrene, polyvinyltoluene, styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, etc. Homopolymers of styrene and its substituted products and copolymers thereof; styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acrylic acid-n-
Copolymers of styrene and acrylic acid esters such as butyl copolymers; styrene and acrylic ester copolymers such as styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, and styrene-butyl methacrylate copolymers. Copolymers with methacrylic esters; multi-component copolymers of styrene with acrylic esters and methacrylic esters; other styrene-acrylonitrile copolymers, styrene-vinyl methyl ether copolymers, styrene-butadiene copolymers, styrene- Styrenic copolymers of styrene and other vinyl monomers, such as vinyl methyl ketone copolymers, styrene-acrylonitrile indene copolymers, styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, poly Vinyl acetate, polyester, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid, phenol resin, aliphatic or alicyclic hydrocarbon resin, petroleum resin, chlorinated paraffin, etc. can be used alone or in combination. In particular, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, higher fatty acid, polyamide resin, polyester resin, etc. are used as binder resins for toners used in pressure fixing systems. Can be used alone or in combination.

A particularly preferred resin for carrying out the present invention is styrene-
There are acrylic ester resins and polyester resins.

In particular, the following formula (wherein R is ethylene or propylene group, x, y
are each an integer of 1 or more, and the average value of X+y is 2 to 10. ) as a diol component, and a carboxylic acid component consisting of a bivalent or higher carboxylic acid, its acid anhydride, or its lower alkyl ester (e.g., fumaric acid, maleic acid, maleic anhydride, phthalate). A polyester resin obtained by co-condensation polymerization with a small amount (eg, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) is more preferable because it has sharp melting characteristics.

In particular, in terms of permeability with traben, the apparent viscosity at 90°C is 5X10' to 5X10'voice, preferably 25
X10'~2XIO' voice, more preferably 106~
10' voids, and the apparent viscosity at 100°C is io
'~5X10' voice, preferably 104~3.0XI
By having O' voice, more preferably 104 to 2X10' voice, a color OHP with good transparency can be obtained, and even as a full color toner, good results can be obtained in fixing properties, color mixing properties, and high temperature offset resistance.

In particular, the absolute value of the difference between the apparent viscosity Pl at 90°C and the apparent viscosity P2 at 100°C is 2XIO'<IPI -P
It is preferable that gI<4X10'.

A charge control agent may be added to the toner according to the present invention in order to stabilize charge characteristics. In this case, a colorless or light-colored charge control agent that does not affect the color tone of the toner is preferred. In the present invention, the present invention becomes even more effective when a negatively charged developer is used, and the negative charge control agent at that time may be, for example, a metal complex of alkyl-substituted salicylic acid (for example, sheet T
organometallic complexes such as ert;-chromium complex or zinc complex of butylsalicylic acid). When the negative charge control agent is added to the toner, it is preferably added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, per 100 parts by weight of the binder resin.

When preparing a two-component developer by mixing with the toner according to the present invention, the mixing ratio is as follows:
Good results are usually obtained from 2.0% to 12% by weight, preferably from 3% to 9% by weight. Toner density is 2. If the ON amount is less than %, the image density will be low and it will not be practical.
If it exceeds 12% by weight, fogging and in-machine scattering will increase, and the useful life of the developer will be shortened.

As the colorant used in the present invention, a wide variety of known dyes and pigments can be used, such as phthalocyanine blue, industhrene blue, peacock blue, permanent red, lake red, rhodamine lake, banza yellow, permanent yellow, benzidine yellow, etc. . Its content is preferably 0.5 to 9 parts by weight.

The method for measuring the amount of triboelectric charge in the present invention will be described below.

The measurement method will be explained in detail using drawings.

FIG. 1 is an explanatory diagram of an apparatus for measuring the amount of triboelectric charge of toner. First, 50 g of a mixture of toner and carrier whose weight ratio is 1:19, whose triboelectric charge amount is to be measured, is placed in a metal measuring container 22 with a 500-mesh screen 23 at the bottom.
The mixture is placed in a polyethylene bottle having a capacity of 50 to 1000 m, shaken by hand 30 times and 500 times, and about 0.5 to 0.9 g of the mixture (developer) is added thereto, and a metal lid 24 is placed. Weigh the entire weight of the measurement container 22 at this time, W + (g)
shall be. Next, in the suction device 21 (at least the part in contact with the measurement container 22 is an insulator), suction is performed from the suction port 27, and the pressure of the vacuum gauge 25 is adjusted to 250 by adjusting the two air volume control valves 26.
Let it be mmAq.

In this state, suction is applied for a sufficient period, preferably about 2 minutes, to remove the toner. The potential of the electrometer 29 at this time is assumed to be ■ (volt). Here, 28 is a capacitor whose capacity is C (LLF). In addition, the weight of the entire measurement container after suction is weighed and is defined as Wz (g). The amount of triboelectric charge of this toner (
μc/g) is calculated as shown below.

[Example] Hereinafter, parts mean parts by weight.

[Real] 100 parts of a 20 wt% toluene solution of 1.1-dihydroperfluorooctyl methacrylate copolymer and 20 parts of a 5.0 wt% methanol solution of the N atom-containing compound shown in Exemplary Compound (m) using a stirrer. A carrier coating solution was prepared by stirring until the mixture was sufficiently mixed.

Apply this coating solution using a coating machine (Nisvira Coater manufactured by Kaida Seiko Co., Ltd.)
It was applied to spherical ferrite particles of Cu-Zn composition with an average particle size of 45 μm.

The obtained coated carrier was dried at 60° C. for 1 hour to remove the solvent, and then heated at 140° C. for 11 hours to obtain a resin-coated carrier.

The resin coating amount of the obtained carrier was 0.61 wt%, and observation using an electron microscope confirmed that the ferrite core material was uniformly coated with the resin.

On the other hand, sufficiently premixed using a Henschel mixer, melt-kneaded using a twin-screw extrusion type kneader, and after cooling, coarsely ground using a hammer mill to approximately 1 to 2 mm, and then using an air jet type fine grinding machine. Finely ground. The resulting finely pulverized product was further classified to obtain a negatively triboelectrically charged cyan powder having a weight average particle size of 8.3 μm.

A cyan toner was prepared by mixing 100 parts of the above colored powder and 0.7 parts of silica fine powder hydrophobized with hexamethyldisilazane. This cyan toner and the above-mentioned carrier were mixed L/L (20°C/10%), N/N (23°C/60%).
%) and H/H (30° C./80%), the toner was mixed at a toner concentration of 5%, and the amount of charge was measured.

In addition, this carrier and cyan toner were mixed at a toner concentration of 5%.
to prepare a developer and set the development contrast to 350.
Using a color copying machine CLC-500 (manufactured by Canon) fixed at
Table 1 shows the results of printing 20,000 images at 80%. It can be seen from Table 1 that the above-mentioned developer exhibits small fluctuations due to environmental changes and is very good.

Note that the following comparative examples and examples are also shown in Table 1.

Image formation was carried out in the same manner as in Example 1 except that the N atom-containing compound was not used in Example 1.
%, the image density decreased to 1.26.

Example 1 except that 1,1-dihydrooctyl methacrylate copolymer was used as the coating material in Example 1.
When a carrier was manufactured in the same manner as above, a good image was obtained from the initial stage to 110,000 sheets, but in a durability test of 20,000 sheets, the image density decreased at 20°C/10% compared to Example 1, especially at 30°C. /
Some toner scattering occurred at 80%.

Therefore, when an original document with an image area ratio of 25% was used, no problem occurred.

In Example 1, a carrier was produced in the same manner as in Example 1 except that 20 parts of the N atom-containing compound was used, and image printing was performed. 1618
and carrier adhesion occurred.

100 parts of a 20 wt% toluene solution of 1.1-dihydroperfluoroethyl methacrylate copolymer and an exemplary compound (
A carrier was produced in the same manner as in Example 1 except that 20 parts of the 5.0 wt% toluene solution of the N atom-containing compound shown in (TV) was used, and when image printing was performed, it was found that it was slightly more environmentally stable than in Example 1. Although the performance decreased, good results were obtained.

Wataru Shigaran In Example 1, the exemplified compound (
When the same procedure as in Example 1 was carried out except that exemplified compound (V) was used instead of III), good results were obtained, although the durability at 30°C and 780% lower temperature was slightly lower.

Mitate 1! , 100 parts of a 20 wt% toluene solution of 1,2.2-tetrahydroperfluorobutylprobylstyrene copolymer and 5.0 wt of the N atom-containing compound shown in Exemplary Compound (I).
A carrier was prepared and imaged in the same manner as in Example 1 except that 20 parts of % methanol solution was used.
Although the durability characteristics below /80% were slightly deteriorated, good results were obtained.

Performed except that 100 parts of a 20 wt% toluene solution of Milk 2 3-perfluorolauryl-2-acetylpropylacetylstyrene and 20 parts of a 5.0 wt% methanol solution of the N atom-containing compound shown in Exemplary Compound (II) were used. A carrier was produced in the same manner as in Example 1, and when images were printed, good results were obtained.

(The following is a blank space) [Effects of the Invention] The present invention provides a color developer containing a color toner and a carrier having a specific additive component in the coating resin, which can stabilize chargeability in various environments and produce high-quality products. An image is obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an apparatus for measuring the amount of triboelectric charge of toner.

Claims (1)

[Claims] (1) Color development comprising at least an insulating nonmagnetic color toner and a carrier coated with an electrically insulating resin of 0.1 to 5.0% by weight based on the weight of the carrier core material and having a weight average particle diameter of 10 to 200 μm. In the carrier core material, the carrier contains a resin containing 0.3 to 15% by weight of a nitrogen-containing compound based on the total coating resin in an organic resin containing at least a fluorinated alkyl acrylic polymer. A color developer characterized by being a carrier coated with.