JPS59136746A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain a positively chargeable toner for dry development having stability to a change in environmental conditions, causing no fog during development, and capable of forming a high quality image by adding a specified piperazinium compound as a charge controlling substance. CONSTITUTION:A piperazinium compound represented by formula I [where Ar is a (substituted) aromatic hydrocarbon group or a (substituted) aromatic heterocyclic group; each of R1 and R<2> is H, (substituted) alkyl or (substituted) aryl; and X<-> is an anion], e.g., a compound represented by formula II is used. A binder (A) such as styrene resin or polyester resin and a coloring agent (B) such as carbon black or aniline blue are blended with said piperazinium compound (C) by about 0.1-10wt% of the amount of the binder to obtain a toner. A magnetic toner may be obtd. by further blending powder of a magnetic body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for developing electrostatically charged images formed in electrophotography, electrostatic printing, electrostatic recording, etc., and more specifically to a positively charged toner for dry development. It is related to toner.

For example, in electrophotography, a photoreceptor made of a photoconductive element is given a uniform surface charge in a dark place, and then imagewise exposed to light to form an electrostatic charge image, which is then transferred to toner and carrier. A visible image is formed by developing the image using a developer consisting of:

In the process of developing an electrostatic image, charged fine particles are attracted by electrostatic attraction and attached to the surface of an electrostatic image support.
This is the process of visualizing the electrostatic charge image.

Generally, there are two methods for developing such electrostatic images: liquid development method and dry development method.The liquid development method uses a liquid developer made by dispersing various pigments or dyes as fine particles in an insulating organic liquid. The dry development method is a development method that uses fine electrostatic detection powder called a toner, which is made by dispersing a coloring agent such as carbon black in a binder made of natural or synthetic resin. It is.

It is preferable to use a dry developing method to develop such an electrostatically charged image. There is a so-called one-component developer that is used alone without being mixed with a carrier.

The two-component developer charges the toner and the carrier to different polarities by stirring and friction, and brings the charged toner into contact with the surface of the silent support.
The electrostatic charge image is developed by adhering the toner to the electrostatic charge image by electrostatic attraction. Development methods using this two-component developer include the magnetic brush method, bristle brush method, impression method, and powder method. Cloud method etc. are known.

In addition, magnetic toner, which is a component-based developer, is developed by a developing method called the magnetic brush method, in which spikes of magnetic toner are made to stand up in the form of a brush on a sleeve by the action of a magnet. The image is developed by bringing it into contact with the surface of the electrostatic image support.

Conventionally, toner for dry development has been prepared by melting and dispersing a coloring agent such as carbon black, a charge control substance, etc. in a binder made of thermoplastic natural resin or synthetic resin, and pulverizing this to obtain particles with a particle size of 5 to 5. Fine particles of about 20 μm are used. Nigrosine dyes are conventionally known as charge control substances used in positively chargeable developing toners.

However, this nigrosine-based dye has poor stability, and may deteriorate due to mechanical friction and impact, changes in temperature and humidity conditions, electrical shock, light irradiation, etc.
Also, during the melt kneading process in the toner manufacturing process, the temperature is approximately 150°C.
It has the disadvantage that when heated to a temperature of 100°C, phenomena such as thermal decomposition occur, resulting in a decrease in charge control performance.

Furthermore, since it is usually difficult for nigrosine dyes to be uniformly melted and dispersed in the binder, there is a difference in charge control performance between the resulting toner particles, and therefore the amount of charge caused by friction between the toner and the carrier is reduced. It has the disadvantage that it is not necessarily uniform and has variations.

For this reason, various methods have been researched to more uniformly melt and disperse nigrosine dyes into binders. For example, a method has been proposed in which basic nigrosine dye, which is used as a charge control substance in positively charged developing toners, is reacted with higher fatty acids to form a salt in order to improve compatibility with the binder. This method has the disadvantage that unreacted higher fatty acids adhere to the optical surface of the carrier in the developer and reduce the fluidity of the developer, resulting in image deterioration. In addition, after mechanically mixing the dye powder and resin powder, so-called premixing, this mixture is heated and melted in a kneading machine, mixed, and kneaded to melt the dye into the binder. A method of dispersion has also been proposed, but this method does not necessarily ensure that the dye is uniformly dispersed and contained in the toner, resulting in variations in the amount of N friction charge. The reality is that a toner that is fully satisfactory for practical purposes has not been obtained.

When a toner containing a structurally unstable dye is used as a developer for an electrophotographic copying machine, there may be variations in charge control performance between toner particles. The friction with the carrier causes variations in the amount of triboelectric charge, resulting in problems such as development capri.

Particularly in copying machines for anti-reflective transfer, where charging, exposure, development, and transfer are repeated, the toner image transfer efficiency is poor, and the toner scatters, contaminating the surface of the electrophotographic material, resulting in decreased sensitivity and This results in problems such as increased fog, and it becomes impossible to continue copying by repeating it many times. Furthermore, the toner scattered within the copying machine causes the disadvantage that the electrical and mechanical functions within the copying machine are deteriorated, and the service life of the copying machine is significantly shortened.

In addition, toners containing nigrosine dyes have an unstable structure as mentioned above, so during storage or transportation, for example, the toner may aggregate and form clumps due to the influence of temperature and humidity. It has the disadvantage of being easily rendered unusable.

As a result of intensive research based on the above circumstances, the present inventors discovered that the above-mentioned drawbacks could be eliminated by using a specific piperazinium compound as a charge control substance, and completed the present invention. I ended up doing it.

An object of the present invention is to provide a positively charged electrostatic image developing toner for dry development that has stable charge control performance even under changes in environmental conditions and can achieve good development without development fog. It is about providing.

The above object is achieved by an electrostatic image developing toner characterized by containing a piperazinium compound represented by the following general formula [■].

General formula [I] [wherein Ar represents a substituted or unsubstituted aromatic carbocyclic group or a substituted or unsubstituted aromatic heterocyclic group, R1 and R2 may be the same or different from each other,
Each represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and X- represents an anion. ] The present invention will be described in detail below.

In the present invention, the piperazinium compound represented by the general formula [1] is contained in a toner using a binder made of, for example, a thermoplastic resin, and the toner for developing electrostatic images is made to contain all other toner components such as a colorant. shall be.

In the toner of the present invention, the content ratio of the piperazinium compound represented by the general formula CD is not particularly limited and can be varied over a wide range, but is usually about 0.1% relative to the binder.
-10% by weight, preferably 0.5-5% by weight.

In addition, in the toner of the present invention, the piperazinium compound represented by the general formula (1) is usually used dispersed in a binder, but the piperazinium compound may be used in any state as long as it can exhibit charge control performance. For example, a method of forming a toner without containing the piperazinium compound in the binder, adding and mixing the piperazinium compound to this toner powder and coating the surface of the toner particles with the piperazinium compound, or a method of using the toner as a toner component. Alternatively, a method may be employed in which the surface of the colorant particles used as the toner particles is coated in advance with the piperazinium compound, and the piperazinium compound is incorporated into the toner particles.

Specific examples of the piperazinium compound represented by the general formula [1] include those having the following structural formula, but are not limited thereto.

Exemplary Compounds (1-1) (I-3) (1-4) As described above, according to the toner of the present invention, the general formula [I]
Because it contains the piperazinium compound shown in
As will be understood from the description of the examples below, regardless of the content state, it is resistant to mechanical friction and impact, changes in temperature and humidity conditions, electrical impact, and changes in the environmental conditions of the light irradiation sieve. Stable characteristics are obtained without deterioration of charge control performance,
Therefore, the charge control performance among the toner particles becomes uniform, and the amount of charge of each toner particle becomes uniform, and as a result, good development without image fogging can be achieved.

Further, according to the toner of the present invention, no problems such as developer fatigue, toner scattering, and toner aggregation were observed, and when the toner of the present invention was used in a copying machine for repeated transfer.

Even when the toner image is transferred, the toner image transfer efficiency is good, and toner scattering does not occur, so there is no contamination inside the copying machine, and as a result, problems such as decreased sensitivity, accelerated fatigue, and increased capri of electrophotographic materials are avoided. , and good development can be carried out repeatedly and stably for a long period of time. Furthermore, since toner scattering does not occur and the interior of the copying machine is less likely to be contaminated, the electrical and mechanical functions within the copying machine are not degraded, and as a result, the service life of the copying machine can be prevented from being shortened.

The reason why the above effects are obtained in the toner of the present invention is not necessarily clear, but the piperazinium compound represented by the general formula [■] has a stable structure and is therefore durable against changes in environmental conditions. It is presumed that this is because the hygroscopicity is small and the compatibility with water molecules is small, so that stable charge control performance is exhibited even with changes in humidity.

As binders that can be used in the toner of the present invention, those conventionally used can be used as they are, and specifically, polystyrene, polyvinyltoluene, styrene-butadiene copolymer, styrene-acrylic ester copolymer polymers or copolymers of styrene or its substituted products such as styrene-maleic anhydride copolymers, polyester resins, acrylic resins, xylene resins, polyamide resins, ionomer resins, ketone resins, terpene resins, phenolic paternal terpenes Resin, rosin, rosin-modified resin, maleic acid-modified phenol resin, petroleum resin, starch graft a combination, polyvinyl alcohol, polyvinylpyrrolidone, etc. can be used alone or in combination. Among these, styrene resins and polyester resins are particularly preferred. The ratio of the binder to the total amount of toner powder is in the range of 30-95%.

The toner components constituting the toner powder together with the above-mentioned binder include a coloring agent, a magnetic material in the case of a magnetic toner,
and additives added as necessary.

Coloring agents include carbon black, aniline blue (
C-L12.50405), Calco Oil Blue (C
, 1, Azoec Blue 3), Chrome Yellow (C.

■, flat 14090), ultramarine blue (C, L
Bay 77103), DuPont Oil Red (C, 1, Boiled 26105), Ki/') Nyero (C, 1, A47
005), methylene blue chloride (C61, A32
015), Phthalocyanine Blue (C,1,A741
60), malachite green oxale) (C,1,
A42000), lamp black (C, 1, flat 7726
6), Rose Bengal (C, 1, A45435),
Mixtures of these and others can be mentioned. These colorants need to be contained in a sufficient proportion to form a visible image of sufficient density, and usually the binder
The ratio is about 1 to 50 parts by weight to 0 parts by weight.

Specific examples of the magnetic material include cobalt, iron, nickel metal powder, aluminum, cobalt, copper, iron, lead,
Alloys of metals such as nickel, magnesium, tin, zinc, gold, silver, selenium, titanium, tungsten, and zirconium, and mixtures thereof; magnetic metal oxides such as aluminum oxide, iron oxide, and nickel oxide; and metal compounds containing these; Ferromagnetic ferrites and mixtures thereof can be produced. These magnetic substances are even dispersed in the toner particles as fine powder, and the proportion thereof is 1 to the total amount of toner powder.
0 to 80% by weight, preferably (d) 35 to 65% by weight. Note that the magnetic material may also exhibit an effect as a coloring agent.

Examples of the present invention will be described below, but the present invention is not limited thereto. "Part" represents part by weight.

Example 1 Styrene-acrylic copolymer “Himer SBM73” (
100 parts of carbon black [Mogul LJ (manufactured by Cavonto), 3 parts of low molecular weight polypropylene "Viscol 660P" (manufactured by Sanyo Chemical Co., Ltd.), and exemplified compound (1-2) Two parts of a piperazinium compound were melted and mixed in a roll mill, cooled, and then finely pulverized in a jet mill.The resulting fine powder was classified using a zigzag classifier to obtain a toner of the present invention having an average particle size of 10 μm.

On the other hand, spherical iron powder rDSP135Cj (manufactured by Dowa Iron Powder Co., Ltd.)
Using a moving bed coating device, coat the particle surface with styrene-methyl methacrylate copolymer (composition ratio: methane: methyl methacrylate = 70:30).
A carrier is manufactured by coating with carrier 9.
A developer is prepared by mixing 8 parts of the toner with 2 parts of the toner.

Using the developer obtained in this manner, photosensitization using a negatively charged two-layer organic photoconductive material using an anthrone pigment as a carrier-generating substance and a carbazole derivative as a carrier-transporting substance. A modified electrophotographic copying machine 1"' U-Bix3000J with a body mounted on it was used to create an atmosphere with a temperature of 30°C and a relative humidity of 80q6, and a temperature of 10°C.
When an actual photographic test was carried out in an atmosphere at a temperature of 20% relative humidity, clear images without capri were obtained in any atmosphere. Next, change the atmospheric conditions and
When a continuous copying test was carried out 20,000 times in an atmosphere with a relative humidity of 50°C and a relative humidity of 50 parts, vivid images with no capri were obtained even after 20,000 copies.
Moreover, toner scattering and developer fatigue were observed. 'I didn't.

Comparative Example In Example 1, rosin liquid nigrosine dye [
A developer was prepared in the same manner as in Example 1 except that Oil Black 5OJ (manufactured by Orient Chemical Co., Ltd.) was used, and a photographic test was conducted in the same manner.
In the 0% atmosphere, images with low image density and blurring were not obtained. Furthermore, when a continuous copying test was carried out in an atmosphere with a temperature of 20°C and a relative humidity of 50%, sagging occurred after the number of copies reached 4,000.
Toner scattering was observed.

Example 2 As a piperazinium compound, 3 parts of Exemplified Compound (I-3) was used instead of Exemplified Compound (1-2), and as a binder, 100 parts of a copolymer consisting of 95 parts of styrene and 5 parts of butadiene was used. Otherwise, a two-component developer was prepared and an image was formed in the same manner as in Example 1. As a result, the obtained image was clear with no development capri and no noticeable difference in density. Furthermore, clear images were obtained even after 20,000 copies, with almost no change from the initial performance.

Furthermore, no contamination inside the aircraft due to toner scattering was observed.

Example 3 Example compound (1-1) was used instead of example compound (1=2) as a piperazinium compound, and a copolymer of 50 parts of styrene, 30 parts of polymethyl methacrylate, and 20 parts of polybutyl methacrylate was used as a binder. Combine 10
A two-component developer was prepared and an image was formed in the same manner as in Example 1, except that 0 part was used.

As a result, a clear image without developing capri is obtained, and 20
Even after copying ,000 times, there was almost no difference from the initial image, and an improvement in transferability was observed.゛Also, no contamination inside the machine due to toner scattering was observed, and there was no deterioration in the durability of the toner.

On the other hand, for comparison, rosin-modified nigrosine dye "Oil Black SO" was used instead of the exemplified compound (■-1) of this example.
'' (manufactured by Orient Chemical Co., Ltd.), a similar experiment was conducted using toner, and the temperature was 20℃ and the relative humidity was 50℃.
% atmosphere, images with low image density and blurring were obtained. Also, toner scattering occurred after copying 5,000 copies.

Example 4 Styrene-Normal Butyl Acrylate r S B M
'73J (manufactured by Kochu Kasei Co., Ltd.) 40 parts Carbon black "Mogalushi" (manufactured by Cabot Corporation) 3 parts Magnetite "B'L-8PJ (manufactured by Titan Kogyo Co., Ltd.) 60 parts Low molecular weight IT
Polypropylene "Viscol 660PJ (manufactured by Kochu Kasei Co., Ltd.) 3 parts Illustrative compound (1-4) 2 parts The mixture of the above composition was melted and mixed in a heated roll mill, and after cooling was pulverized in a jet mill. The resulting fine powder was classified. A one-component toner with an average particle size of 12 μm was obtained by classification using a machine. Using this -component toner, a “U Bix TJ Modified 0!” equipped with the same photoreceptor as in Example 1 was used. temperature 20
℃ in an atmosphere of 50% relative humidity, a clear image without fogging was obtained. 15. O'00
Clear images with no fogging were obtained even after continuous copying of multiple sheets.

For comparison, when nigrosine dye (manufactured by Orient Chemical Co., Ltd.) was used in place of exemplified compound (1-4), s, oo
The readability of characters decreased after continuous copying of o sheets.

Claims (1)

[Scope of Claims] 1) A toner for developing electrostatic images, characterized by containing a piperazinium compound represented by the following general formula [I]. General formula [■] 2 [In the formula, Ar represents a substituted or unsubstituted aromatic carbocyclic group or a substituted or unsubstituted aromatic polycyclic group, and R1 and R2 may be the same or different from each other. ,
a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted alkyl group, respectively. It represents an unsubstituted aryl group, and X- represents an anion. ]