JPH0561263A - Color developer - Google Patents

Abstract

PURPOSE:To provide the color developer stable in triboelectrification characteristics and small in effect due to variation of environmental conditions. CONSTITUTION:The color developer comprises at least an insulating and nonmagnetic color toner and a carrier obtained by coating a carrier core with an insulating resin in an amount of 0.1-5.0 weight%, and the carrier is characterized by having a volume resistivity of 10<9>= 10<12>OMEGA.cm and an average particle diameter of 10-200mum, and using the insulating resin containing a fluorinated block polymer resin and a compound containing an N atom and triboelectrifiable in reverse polarity to the toner in an amount of 0.3-15weight % of the fluorinated block polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used for developing an electric latent image or a magnetic latent image in an electrophotographic method, an electrostatic printing method or the like, and particularly, the image quality of a color image is remarkably improved. It relates to a color developer.

[0002]

2. Description of the Related Art Conventionally, a method of developing an electrostatic latent image with toner in an electrophotographic method is roughly classified into a method of using a so-called two-component developer in which a small amount of toner is dispersed in a medium called a carrier and a method of using a carrier. There is a method of using a so-called one-component developer in which the toner is used alone without using it. The present invention relates to a two-component developer composed of a toner and a carrier among the above developers. The carrier that constitutes the two-component developer is roughly divided into a conductive carrier and an insulating carrier, and oxidized or unoxidized iron powder is usually used as the conductive carrier. A developer containing the iron powder carrier as a component. However, there is a drawback in that the triboelectrification property with respect to the toner is unstable and the visible image formed by the developer is apt to be fogged. That is, as the developer is used, the toner particles adhere to and accumulate on the surface of the iron powder carrier particles (spent toner), so that the electric resistance of the carrier particles increases, the bias current decreases, and the triboelectrification property increases. The image becomes unstable, and as a result, the image density of the visible image is lowered and the fog is increased. Therefore, if a developer containing an iron powder carrier is continuously used for copying with an electronic copying apparatus, the developer deteriorates in a small number of times, so that it is necessary to replace the developer early, resulting in high cost. Will be things.

The insulating carrier is typically a carrier obtained by uniformly coating the surface of a carrier core material made of a ferromagnetic material such as iron, nickel or ferrite with an insulating resin. In the developer using this carrier, the toner particles are not significantly fused to the carrier surface as compared with the case of the conductive carrier, and at the same time, it is easy to control the triboelectrification property between the toner and the carrier, and the durability is improved. It has an advantage that it is particularly suitable for high-speed electronic copying machines in that it has a long service life.

However, in this insulative carrier, the carrier itself is strongly charged with a polarity opposite to that of the toner particles, which not only causes the problem of carrier adhesion to the background portion, but also the toner spent on the carrier surface. Is also increased.

This tendency is remarkable in the non-magnetic color toner which does not have leak sites in the toner itself, and is particularly enhanced when the colorant-containing resin particles using a polyester binder having a high chargeability are used as the toner. , Especially in low humidity.

As a countermeasure against this, on the carrier side,
For the purpose of eliminating carrier adhesion that occurs because the carrier itself is strongly charged, it has been proposed to coat the carrier by dispersing, for example, conductive carbon black in the coating resin, but so far It cannot be said that a stable coating state has been achieved, and release of carbon black and the like due to long-term use causes new problems such as fog.

Further, although examples of coating a fluororesin or a silicone resin having a small surface energy have been proposed, a carrier coated with such a resin having a small surface energy has a slow rise in charging of the toner, and At present, there is still no satisfactory carrier because toner scattering easily occurs under high humidity.

[0008]

The present invention provides a color developer which does not have the above-mentioned drawbacks, and provides a color developer having stable triboelectrification characteristics and excellent carrier adhesion prevention. Is.

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

Another object of the present invention is to provide a long-lived color developer having stable developing ability by preventing toner spent on the surface of the carrier from occurring and by firmly adhering the carrier coating resin.

Another object of the present invention is to provide a color developer which has a good start-up of charging and a small fluctuation in charging characteristics and provides an extremely stable image with respect to environmental changes.

[0012]

The color developer of the present invention comprises at least 0.1 to 5.0% by weight of an electrically insulating resin with respect to the insulating non-magnetic color toner and carrier core material, and has a volume of The weight average particle diameter of the carrier core material coated so that the specific resistance is 10 ⁹ to 10 ¹² Ωcm is 10 to 20.
In a color developer with a carrier that is 0 μm,
The electrically insulating resin has a fluorine-containing block polymer resin and a compound containing a nitrogen atom that is charged in a polarity opposite to that of the toner with respect to the carrier core material, and the compound containing the nitrogen element is a fluorine-containing compound. The above object is achieved by being characterized by being contained in an electrically insulating resin in an amount of 0.3 to 15% by weight based on the block polymer resin containing

Up to now, examples of using a compound containing a nitrogen atom as a carrier coating agent include, for example,
JP-A-59-124345 discloses an example in which a tertiary amine as a compound having an amine structure is contained as a charge control agent.

However, in the above carrier structure,
When the non-magnetic color toner of the present invention is combined with the insulating non-magnetic color toner having no conductive member such as magnetic powder or carbon black, the initial characteristics are certainly good, but in continuous copying over a long period of time, It has been found that the initial level cannot always be maintained, and there are problems such as a decrease in image density and deterioration of fog.

In addition, Japanese Patent Laid-Open No. 59-124346 discloses an example in which N-vinylcarbazoles are contained, but the above example is merely a carrier for positively chargeable toner, and the present invention is not limited to this. Is something completely different.

Further, attaching a quaternary ammonium salt as a compound having an ammonium salt structure to the surface of a carrier is disclosed in, for example, JP-A-62-229256. In the above-mentioned publication, the quaternary ammonium salt is disclosed. Is not contained in the resin and is completely different from the present invention. Further, when used as a coating material for a block copolymer containing fluorine and a carrier,
JP-A-61-80161 and JP-A-62-3988
As disclosed in Japanese Patent Publication No. 1 etc., these fluorine-containing block polymers are significant in terms of stain resistance of the carrier surface, but the difference in the environment, especially the change in the charge amount due to the temperature change is considerably large, and the high humidity is high. When an original document having a high image area ratio is continuously copied below, charging is not sufficiently imparted, and toner scattering does not occur, which is not satisfactory.

The reason why the carrier in which the fluorine-containing block polymer of the present invention is coated with a compound containing a nitrogen atom which is charged in a polarity opposite to that of the toner is extremely effective for stabilizing charging is surface energy. This is because the compound described above compensates for the delay in charging the toner of the small fluororesin to the toner.

Moreover, it has been found that a carrier containing an ammonium salt particularly plays a role of lowering the absolute value of tribo under low humidity.

The reason for this is not clear yet, but it is presumed that the nitrogen compound contained in the present invention forms a leak site against the phenomenon that the toner is charged up.

As the compound containing a nitrogen atom according to the present invention, general compounds such as an aliphatic amine having an amine structure, an alicyclic amine and an aromatic amine can be used. Among them, the compounds represented by the following formulas I and II are particularly preferable in terms of having a rise in charge and a leak function. In the tertiary amine represented by the formula I, R ₁ , R ₂ and R ₃ are hydrogen atoms or hydrocarbons, but compounds having 6 or less carbon atoms are preferable. R ₁ , R ₂ and R ₃ may each have a linear structure or a branched structure, but are particularly preferably linear. Is good.

[0021]

[Outer 1]

Next, the quaternary ammonium salt represented by the above formula II will be described.

R ₄ , R ₅ , R ₆ and R ₇ represent a hydrogen atom or a hydrocarbon. Of these, compounds having 8 or less carbon atoms are preferable.

Specific examples of A in the above general formula include an organic sulfate ion, an organic sulfonate ion and an organic phosphate ion, preferably an organic anion, and more preferably an aromatic anion. The reason is,
The use of a quaternary ammonium salt that is sparingly soluble or insoluble in water is a major feature of the present invention. When A is the above-mentioned anion, it becomes a water-insoluble quaternary ammonium salt and is eluted under high humidity. That is, the property of not desorbing is obtained.

In the present invention, it is preferable that the quaternary ammonium salt is compatible with the resin so that the quaternary ammonium salt is uniformly present on the surface of the carrier, but it is not necessarily limited thereto.

Specific compound examples of the compound having a nitrogen atom according to the present invention are shown below.

[0027]

[Outside 2]

The electrically insulating resin coating the surface of the carrier core material according to the present invention has a block copolymer,
The block copolymer can be divided into a main segment and a sub segment that share functions.

The proportion of the main segment to all block copolymers is preferably 51 to 90% by weight, more preferably 55 to 80% by weight.

As the main segment, styrene, acrylic ester, methacrylic, ester or the like is used alone or 2
A combination of two or more species can be used. For example, polymethyl acrylate, polybutyl acrylate, polybutyl acrylate, methyl polymethacrylate, ethyl polymethacrylate, butyl polymethacrylate, polystyrene, chloropolystyrene, poly-α-methylstyrene,
Styrene-chlorostyrene copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, styrene-methyl methacrylate copolymer Polymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, styrene-α-
Examples thereof include methyl chloroacrylate copolymer.

The sub-segments include homopolymers or copolymers of at least one monomer having fluorine selected from tetrafluoroethylene, vinylidene fluoride, vinyl fluoride, trifluorochloroethylene, dichlorodifluoroethylene. Examples include polymers.

The above-mentioned compound having nitrogen is 0.3 to 15% by weight of the fluorine-containing block polymer resin.
It is necessary to contain the carrier core material in the electrically insulating resin in an amount of 0.1 to 8.0% by weight, preferably 1.0 to 8.0% by weight. The content of the compound having nitrogen is
If it is less than 0.3% by weight, the effect of adding the nitrogen-containing compound is not sufficiently exhibited, and if it exceeds 15% by weight, the rise of charging is slightly delayed.

As the carrier core material according to the present invention, all commonly used materials such as iron powder and ferrite powder can be used.

The coating amount of the electrically insulating resin with which the carrier core material according to the present invention is coated is preferably 0.1% by weight to 30% by weight of resin solid content,
More preferably, 0.2 wt% to 10 wt% is good.

When the resin solid content is less than 0.1% by weight, the effect of coating the carrier core material with the resin is not sufficient,
On the other hand, when it exceeds 30% by weight, there is no merit due to an increase in the resin solid content, and there is a case where an excessive resin alone exists from the viewpoint of production, which is not preferable.

In the present invention, it has been stated that all commonly used carrier core materials such as iron powder and ferrite powder can be used. This is because the electrically insulating resin according to the present invention is used. This is one of the major features of using.

The particle size of the carrier core material is 10 to 20.
0 μm is preferable, and 20 to 65 μm is more preferable.

Particularly, as the material of the magnetic particles as the carrier core material used in the present invention, Cu-Z of 98% or more is used.
n-Fe (metal composition ratio (5 to 20): (5 to 20):
Ferrite particles having a composition of (30 to 80) are preferable because the surface can be easily made uniform and the charging ability is stable.

The binder used in the non-magnetic insulating color toner according to the present invention includes polystyrene and poly-p-
Chlorostyrene, polyvinyltoluene, styrene-p-
Homopolymers of styrene and its substitution products such as chlorostyrene copolymers, styrene-vinyltoluene copolymers, and copolymers thereof; styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers, styrene −
Copolymer of styrene and acrylic ester such as acrylic acid-n-butyl copolymer; styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic acid-n-butyl copolymer Polymers of styrene and acrylic ester such as coalesce; multi-component copolymer of styrene and acrylic ester and methacrylic ester; other styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-butadiene copolymer Polymers, styrene-vinyl methyl ketone copolymers, styrene-acrylonitrile indene copolymers, styrene-maleic acid ester copolymers, etc. Styrene-based copolymers of styrene and other vinyl-based monomers; polymethylmethacrylate, Polybutyl methacrylate, polyvinyl acetate, Riesuteru, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid,
Phenolic resins, aliphatic or alicyclic hydrocarbon resins, petroleum resins, chlorinated paraffins, 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 as a binder resin for toner that is subjected to a pressure fixing method,
Polyester resins and the like can be used alone or in combination.

Particularly preferable resins for carrying out the present invention are styrene-acrylic acid ester resins and polyester resins.

In particular, the following equation

[0042]

[Outside 3] (In the formula, R is an ethylene or propylene group, and x, y
Are each an integer of 1 or more, and the average value of x + y is 2 to 10. ), A bisphenol derivative or a substitution product represented by the formula (1) is used as a diol component, and a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, phthalate). An acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) is more preferable because it has a sharp melting property.

Particularly, in terms of transparency with trapene, 90 ° C.
Has an apparent viscosity of 5 × 10 ^{4 to} 5 × 10 ⁶ poises, preferably 25 × 10 ⁴ to 2 × 10 ⁶ poises, more preferably 10 ⁵ to 10 ⁶ poises, and an apparent viscosity at 100 ° C. of 10 ⁴ ~ 5 × 10 ⁵ poise, preferably 10 ⁴ ~ 3.0
A color OHP having good transparency can be obtained by setting the porosity to 10 ⁵ poise, more preferably 10 ⁴ to 2 10 ⁵ poise, and a good result can be obtained even in the case of a full-color toner, in which fixability, color mixing property, and high temperature offset resistance are good. Be done.

Apparent viscosities P ₁ and 100 at 90 ° C.
The absolute value of the difference from the apparent viscosity P _{2 at} ℃ is 2 × 10 ⁵ <|
It is preferable that P ₁ -P ₂ | <4 × 10 ⁶ .

A charge control agent may be added to the toner according to the present invention in order to stabilize the charge characteristics. At that time, a colorless or light-colored charge control agent that does not affect the color tone of the toner is preferable. In the present invention, when a negatively chargeable developer is used, the present invention becomes more effective. As the negatively charge control agent in that case, for example, a metal complex of alkyl-substituted salicylic acid (e.g., chromium complex of di-tert-butylsalicylic acid) is used. Or an organometallic complex such as a zinc complex). When the negative charge control agent is added to the toner, the binder resin 10
0.1 to 10 parts by weight, preferably 0.
It is preferable to add 5 to 8 parts by weight.

When a two-component developer is prepared by mixing with the toner according to the present invention, the mixing ratio is such that the toner concentration in the developer is 2.0% by weight to 12% by weight, preferably 3% by weight to 9% by weight. Good results are usually obtained with a weight percentage. If the toner density is 2.0% or less, the image density is low and it becomes unpractical, and if it is 12% or more, fog and scattering in the machine increase
Shortens the useful life of the developer.

As the colorant used in the present invention, known dyes and pigments such as phthalocyanine blue, induslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine yellow and the like are widely used. be able to. The content is preferably 0.5 to 9% by weight with respect to the non-magnetic insulating color toner.

The measuring method of the present invention will be described below. (1) Triboelectric charge measurement: The measuring method will be described in detail with reference to the drawings.

FIG. 1 is an illustration of an apparatus for measuring the amount of triboelectric charge of toner. First, 50 g of a mixture of a toner and a carrier having a weight ratio of 1:19, whose weight is to be measured triboelectrically, is placed in a metal measuring container 22 having a 500 mesh screen 23 in a polyethylene bottle having a capacity of 50 to 100 ml. After shaking by hand 30 to 500 times, about 0.5 to 0.9 g of the mixture (developer) is put and a metal lid 24
do. At this time, the weight of the entire measuring container 22 is weighed and W ₁
(G). Next, in the suction device 21 (at least the part that is in contact with the measurement container 22 is an insulator), suction is performed from the suction port 27 to adjust the air volume control valve 26 to adjust the pressure of the vacuum gauge 25 to 2
It is set to 50 mmAq. This state is sufficient, preferably about 2
Suction for a minute to remove the toner by suction. The potential of the electrometer 29 at this time is V (volt). Here, 28 is a capacitor, and the capacitance is C (μF). The weight of the entire measuring container after suction is weighed and is W ₂ (g). The triboelectric charge amount (μc / g) of this toner is calculated by the following equation.

[0050]

[Outside 4]

[0051]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 100 parts by weight of a toluene solution of 20% by weight of the block polymer shown in A of Table 1 obtained by a photopolymerization reaction and 5.0% by weight of the quaternary ammonium salt shown in Specific Compound Example II. 20 parts by weight of the methanol solution of was mixed with a stirrer until sufficiently mixed to prepare a carrier coating solution.

This coating solution was applied to spherical ferrite particles of Cu--Zn composition having an average particle size of 45 μm by a coating machine (Spiracoater, manufactured by Okada Seiko Co., Ltd.).

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

The resin coating amount of the obtained carrier was 0.6.
It was 1% by weight, and it was confirmed by observation with an electron microscope that the ferrite core material was uniformly coated with the resin.

[0056]

[Table 1]

On the other hand, 100 parts by weight of a polyester resin obtained by condensing propoxylated bisphenol and fumaric acid. 5 parts by weight of phthalocyanine pigment. Chromium complex salt of diethyl butylsalicylic acid.
Parts by Weight The above materials were sufficiently premixed with a Henschel mixer, kneaded with a twin-screw extruder, cooled, and coarsely pulverized with a hammer mill to a particle size of about 1 to 2 mm. Then, it was pulverized by an air jet pulverizer. Further, the obtained finely pulverized product was classified to obtain a cyan powder having a negative triboelectrification property and a weight average particle diameter of 8.3 μm.

Cyan toner was prepared by mixing 100 parts by weight of the obtained cyan powder with 0.7 part by weight of fine silica powder hydrophobized with hexamethyldisilazane.

The cyan toner and the above-prepared carrier were placed under a low temperature and low humidity environment of a temperature of 20 ° C. and a humidity of 10% RH.
Temperature 23 ℃ / humidity 60% RH, normal temperature and humidity environment, temperature 3
After being left in each environment of high temperature and high humidity of 0 ° C./80% RH, the carrier and the toner were mixed at a toner concentration of 5%, and the charge amount was measured. The results are shown in Table 2.

Further, using a color developer obtained by mixing carrier and cyan toner at a toner concentration of 5%, a commercially available color copying machine CLC-500 (manufactured by Canon Inc.) whose development contrast was fixed at 350V, Image area ratio 5%
Using the original manuscript, the temperature is 20 ℃ and the humidity is 10
Table 2 shows the results of printing 20,000 sheets under each environment of% RH, temperature 23 ° C./humidity 60% RH, temperature 30 ° C./humidity 80% RH.

As a result, the above-mentioned color developers were very good with little influence on environmental changes.

(Comparative Example 1) Image formation was carried out in the same manner as in Example 1 except that the quaternary ammonium salt shown in Specific Compound Example II in Example 1 was not used. Temperature 20 ° C / humidity 10 Image density is 1. under environmental conditions of% RH.
It fell to 12.

The results are shown in Table 2.

(Comparative Example 2) Image formation was carried out in the same manner as in Example 1 except that vinylidene fluoride was not used, and good images were obtained from the initial stage to 10,000 sheets. However, as shown in Table 2, in the endurance test of 20,000 sheets, the image density was lower in the environment of temperature 20 ° C./humidity 10% RH than in Example 1, and particularly, temperature 30 ° C./humidity 80% RH
Toner scattering occurred a little under the above environment. Therefore, when an original document having an image area ratio of 25% was used, no problem occurred.

Comparative Example 3 Instead of the carrier coating solution used in Example 1, a polyvinylidene fluoride-tetrafluoroethylene copolymer 20% by weight toluene solution 1 was used.
A carrier was prepared in the same manner as in Example 1 except that 100 parts by weight of the carrier coating solution was used.
As shown in Table 2, coating unevenness occurred and free resin powder was generated.

(Comparative Example 4) In Example 1, image formation was performed in the same manner as in Example 1 except that the amount of the quaternary ammonium salt used was 20 parts by weight. As described above, the image density decreased to 1.22 in the environment of temperature 20 ° C./humidity 10% RH, and carrier adhesion occurred.

Example 2 100 parts by weight of a toluene solution of 20% by weight of the block polymer shown in B of Table 1 obtained by the photopolymerization reaction and 4 shown in Specific Compound Example III
A carrier was prepared and imaged in the same manner as in Example 1 except that 20 parts by weight of a 5.0 wt% methanol solution of a primary ammonium salt was used, and as shown in Table 2, Example 1 was used. Although the environmental stability was slightly lower than that of, good results were obtained.

Example 3 4 used in Example 1
Example 1 except that the triphenylamine shown in Specific Compound Example IV was used in place of the primary ammonium salt.
When an image was formed in the same manner as in, good results were obtained as in Example 1 as shown in Table 2.

Example 4 4 used in Example 1
Image formation was carried out in the same manner as in Example 1 except that the diphenylamine shown in Specific Compound Example VI was used in place of the primary ammonium salt, and as shown in Table 2, temperature 30 ° C./humidity 80% In the RH environment, good results were obtained although the durability characteristics were slightly lowered.

[0070]

[Table 2]

[0071]

According to the color developer of the present invention, the electrically insulative resin with which the carrier core material is coated has a fluorine-containing block polymer resin and a carrier core material that is charged with a polarity opposite to that of the toner. Since the compound having an atom is contained, and the compound having a nitrogen atom is contained in the electrically insulating resin in an amount of 0.3 to 15% by weight of the block polymer resin containing fluorine, the following effects are obtained. Have. It has stable triboelectrification characteristics and is excellent in preventing carrier adhesion. Little toner scattering. Toner spent is unlikely to occur on the carrier surface, and the carrier coating resin adheres firmly, so that stable developing ability and long life are provided. The start-up of charging is good and the fluctuation of charging characteristics is small and stable.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus for measuring a triboelectric charge amount of toner used in the present invention.

[Explanation of symbols]

 21 Suction Machine 22 Measuring Container 23 Conductive Screen 24 Lid 25 Vacuum Gauge 26 Air Volume Control Valve 27 Suction Port 28 Condenser 29 Electrometer

Claims (2)

[Claims] 1. A carrier containing at least 0.1 to 5.0% by weight of an electrically insulating resin based on at least an insulating non-magnetic color toner and a carrier core material and having a volume resistivity of 10 ⁹ to 10 ¹² Ωcm. The weight average particle size of the core material is 10
In a color developer having a carrier of 200 μm, the electrically insulative resin has a fluorine-containing block polymer resin and a compound containing a nitrogen atom charged to the carrier core material in a polarity opposite to that of the toner, The color developer, wherein the compound containing a nitrogen element is contained in the electrically insulating resin in an amount of 0.3 to 15% by weight based on the block polymer resin containing fluorine. 2. The color developer according to claim 1, wherein the compound containing a nitrogen atom has a nitrogen-containing compound containing 3 to 30 carbon atoms per 1 atom of nitrogen.