JPH0980811A - Developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve moisture resistance and to always obtain a good image regardless by of environmental conditions by constituting a developer of toner particles and a flowability improving agent to be externally added to the surface of particles and specifying the acid value of the binder resin which constitutes the toner particles. SOLUTION: A toner carrier 1 is disposed in a developer tank T in such a manner that the carrier 1 can rotate around an axis 6. A back electrode 2 is disposed for the toner carrier 1 and a matrix-type recording electrode 3 is disposed between the toner carrier 1 and the back electrode 2. A developer on the toner carrier 1 is sprayed to the recording body 4 to form an image. The developer used is prepared by adding and mixing 20-60wt.% coloring agent to a binder resin having <=20KOHmg/g acid value, solidifying the mixture and pulverizing into fine particles of toner particles. Further, a flowability improving agent is externally added by 0.2-1.0wt.% of the amt. of the toner particles to the surface of the toner particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct recording apparatus for forming a toner image by keeping a recording electrode and a recording medium such as paper in non-contact with each other and directly ejecting toner from a toner carrier onto the recording medium. Regarding the developer used.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic apparatus has been generally used as an apparatus for forming a document or a figure on a recording medium. However, in the electrophotographic apparatus, it is necessary to separately provide a means for forming a latent image on the surface of the image carrier and a means for developing the latent image, so that the structure becomes complicated and the size tends to increase.

Therefore, a recording electrode and a back electrode are arranged to face the toner carrier, a recording medium such as paper is conveyed between the recording electrode and the back electrode, and an image signal is fed between the recording electrode and the counter electrode. A direct recording device has been proposed in which a voltage corresponding to is applied to generate an electrostatic force on the toner, and the toner is ejected from the toner carrier to the recording body according to the voltage application state.

Various structures have been proposed for a direct recording device, one of which is a recording electrode in which a plurality of conductors are arranged in a matrix, and a voltage is applied to each of the conductors at the same time so that a magnet roll is formed. A method is proposed in which the toner held on the recording electrode is electrostatically ejected from the mesh of the recording electrode and selectively adheres to the surface of the recording body (Japanese Patent Laid-Open Nos. 4-505896 and 4-5058).
No. 99). Further, as the toner used in the above-mentioned direct recording method, there is no special toner for the method, and a means for forming a latent image on the image carrier surface and a means for developing the latent image are separately provided. The toner used in the provided normal image forming apparatus is used. The toner includes magnetic toner containing magnetic powder and non-magnetic toner containing colorant but not magnetic powder. These toners contain a fixing resin having an acid value of 3 KOH mg / g or more and 50 KOH mg / g or less and carbon black having a PH of 7 or more to improve the moisture resistance, thereby causing fogging and an electrostatic latent image holding member. There is a proposal of a toner which prevents stains on the surface (Japanese Patent Application Laid-Open No. 5-134).
452). However, this toner is an ordinary electrophotographic method in which a means for forming a latent image on the surface of an image carrier and a means for developing the latent image are separately provided, and the toner is used for a direct recording method having a different image forming method. Even if it is applied, a preferable image cannot be obtained.

[0005]

In the above-described direct recording apparatus, a mixture of a binder resin and magnetic powder is formed into fine toner particles as a toner to be blown from the toner carrier to the recording body, and the toner is flown to the outer periphery thereof. A conventional toner to which a property improving agent is externally added,
Alternatively, a toner is known in which the acid value of the fixing resin is specified to improve the moisture resistance. However, when an image is created using the above toner with a direct recording device, if the image is created when environmental conditions such as temperature and humidity are bad, there are problems that the image density is lowered and the image is fogged. It was

Such a decrease in the image density is required for the toner in the direct recording device because the toner is directly ejected from the toner carrier to the recording medium through the mesh-shaped recording electrode in the direct recording device. This condition is considered to be different from the toner condition required in the image forming apparatus of the type that forms a latent image on the surface of the image carrier and develops it. According to the research by the present inventor, when the density of an image directly obtained by a recording apparatus is lowered, the image density is improved by replenishing the toner containing section for supplying the toner to the toner carrier or improving the environmental condition. Returned to good. From this, it is known that when an image is created directly by a recording device when the environmental conditions such as temperature and humidity are a little bad, the image density is affected by the fluidity of the toner, and the fluidity is greatly affected by the moisture resistance. The developer of the present invention having sufficient moisture resistance was completed. According to the present invention, a developer used for a direct recording apparatus is composed of toner particles and a fluidity improver externally added to the surface of the toner particles, and the developer is obtained by specifying the acid value of a binder resin forming the toner particles. It is an object of the present invention to improve the moisture resistance of No. 1 and to always obtain a good image regardless of environmental conditions such as temperature and humidity when an image is directly produced by a recording apparatus.

[0007]

According to the present invention, a back electrode is arranged facing a toner carrier and a recording electrode in a matrix is arranged between the toner carrier and the back electrode, and A developer which is used in a direct recording device in which toner is ejected from a toner carrier to a recording body between a recording electrode and a back electrode according to the state of voltage application, and achieves the above object. The developer has an acid value of 15
0.2 to 1.0 parts by weight of a fluidity improver is externally added to 100 parts by weight of toner particles, to toner particles containing a binder resin of KOH mg / g or less and 5 to 60% by weight of a colorant. It is characterized by being.

The reason why the acid value of the binder resin is set to 15 KOH mg / g or less is that when it is larger than that, a large amount of polar groups (functional groups) are present in the binder resin, and when the toner is constituted, This is because the moisture resistance decreases. As the preferred binder resin, one or more of styrene resins such as polystyrene and styrene-acrylic copolymers, polyester resins, epoxy resins and phenol resins can be applied. The binder resin may be appropriately set according to the fixing system (see, for example, JP-A-57-97545). As an example, in the case of the heat roll fixing method, a styrene-acrylic copolymer, a styrene-butadiene copolymer, a polyester resin, an epoxy resin and a mixed resin thereof are suitable.

The content of the colorant is set to 5 to 60% by weight because the image color is unclear when the content is less than 5%.
This is because if it is more than%, the fixability is lowered. As the colorant, one or more of pigment, dye, or magnetic powder of magnetite or ferrite can be applied. When colored magnetic powder such as magnetite or ferrite is included in the binder resin to form a magnetic toner, it is not necessary to additionally include a pigment or dye. In that case, if the content of the magnetic powder is less than 20% by weight, the saturation magnetization of the toner is lowered and the toner is easily separated from the toner carrier, and if it exceeds 60% by weight, the toner itself is conductive. Volume resistance and the fixability are poor. Therefore, the preferable content is 20 to 40% by weight. The magnetic powder has a coercive force ( _I H _c ).
Is preferably 50 to 500 Oe. The magnetic characteristics are measured by applying a maximum magnetic field of 10 kOe with a vibrating sample magnetometer (VSM-3 manufactured by Toei Industry Co., Ltd.).

The amount of the fluidity-improving agent added externally depends on the toner particles 10.
0.2 to 1.0 parts by weight with respect to 0 parts by weight,
This is because if it is less than 0.2 parts by weight, the effect is not obtained, and if it is more than 1 part by weight, the charging property is too high. The method of externally adding the fluidity improver may be, for example, to put the toner particles and the additive in a known mixer and to stir for a predetermined time. Flowability improvers include hydrophobic SiO ₂ and TiO ₂ .
₂ , Al ₂ O _{3 and the} like can be applied, and their primary particle diameter is preferably 0.01 to 0.5 μm. The primary particle size of the fluidity-improving agent is 0.01 to 0.5 μm because
If it is smaller than 01 μm, secondary aggregation tends to occur,
Difficult to attach to the toner surface. On the contrary, the reason is that even if it is larger than 0.5 μm, it is difficult to stably adhere to the toner surface.

In order to have hydrophobicity, fine powder such as SiO _{2 is used} as R _m SiY _n (R is an alkoxy group or a chlorine atom, m is an integer of 1 to 3, and Y is an amino group. , Vinyl group, glycidoxy group, methylcapto group,
A hydrocarbon containing at least one or two or more of a methacryl group and an ureido group, n is an integer of 3 to 1), and the degree of hydrophobicity measured by a methanol titration test is It processes so that the value of the range of 30-80 may be shown. In order to set the degree of hydrophobicity within the range of 30 to 80, a known hydrophobicization method can be applied. For example,
It can be provided by chemically treating with an organic silicon compound which reacts with or physically absorbs the fine silica powder.
A preferred method is to treat the silica fine powder produced by the above-mentioned oxidation of a silicon halogen compound with the above-mentioned silane coupling agent, or simultaneously with the silane coupling agent, and simultaneously treat with the organosilicon compound. Such organosilicon compounds include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, Prommethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptans such as trimethylsilylmercaptan, triorganosilylacrylates such as vinyldimethyl. Acetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, hexamethyldisiloxane,
1,3-divinyltetramethyldisiloxane, 1,3-
There are diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and having one hydroxyl group bonded to each of the terminally located units bonded to Si. It can be used as a mixture of two or more kinds. A preferable weight ratio of the silane coupling agent compound and the hydrophobizing agent to be treated with respect to the silica fine powder is 15:85 to 15,
The total amount of the silane coupling agent and the hydrophobizing treatment is preferably 0.1 to 30 wt%, and more preferably 0.5 to 20 wt% with respect to the silica fine powder. Further, as a fluidity improver, acrylic, polypropylene,
Fine powder of nylon, polyurethane, polyethylene, silicone resin or polymethylmethacrylate resin can be used.

A small amount of a charge control agent or a release agent may be added to and mixed with the above toner particles. As the release agent, polyolefin such as polyethylene and polypropylene can be applied. A known dye or pigment can be used as the charge control agent. For example, a nigrosine dye having a positive triboelectricity and a metal-containing azo dye having a negative triboelectricity are listed. The content of the charge control agent is preferably set in the range of 0.1 to 5% by weight in order to obtain a predetermined charge amount. This is because when the charge control agent is more than 5%, the moisture resistance is lowered.

The above developer used in the direct recording apparatus is
The toner particles are mixed with a binder resin having an acid value of 15 KOH mg / g or less and 5
Since the fluidity improver is externally added to the toner particles containing up to 60% by weight of the colorant, the moisture resistance is improved and the fluidity of the developer is kept good even when the environmental conditions of temperature and humidity are bad. Be drunk Therefore, even when an image is directly formed by the recording device under bad environmental conditions, the magnetic toner can be reliably and accurately ejected from the toner carrier to the recording medium via the recording electrode, and the image density can be improved. It is possible to obtain a good quality image without any fog.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The developer of the present invention is used in the direct recording apparatus shown in FIG. The direct recording device is a developer tank T.
A cylindrical toner carrier 1 is rotatably provided via a shaft 6, a back electrode 2 is arranged so as to face the toner carrier 1, and a matrix shape is provided between the toner carrier 1 and the back electrode 2. Recording electrodes 3 are arranged. To the recording electrode 3,
A voltage can be applied so as to correspond to the image to be recorded, and the recording medium 4 such as paper is conveyed between the recording electrode 3 and the back electrode 2 to record the developer on the toner carrier 1. An image is formed by being struck on the body 4. An iron doctor blade 5 is provided so as to face the toner carrier 1, and the thickness of the toner attached to the sleeve is regulated to be small.

The toner carrier 1 is made of SUS 30 having an outer diameter of 32 mm.
4 Inside the sleeve 1a, multiple poles (4 in Fig. 1)
A permanent magnet body 1b having a roll shape is arranged, and a DC voltage source is connected between the sleeve 1a and the back electrode 2. Then, the developer in the developer tank T is attached onto the sleeve 1a, and the magnetic toner is conveyed to the surface facing the recording electrode 3 by the relative rotation of the sleeve 1a and the magnet body 1b. In the above, the sleeve 1a
Although the thickness of the upper developer layer is regulated by the doctor blade 5, the thickness of the developer layer may be regulated by pressing the blade 7 against the sleeve 1a as shown in FIG. In this case, it is possible to use the toner carrier 1 formed of a rubber mag roll in which magnetic powder is dispersed in a rubber material. Further, in the above-mentioned direct recording device, the developer is a magnetic toner, but when the developer is a non-magnetic toner, the toner carrier 1 is formed by a rubber roll formed of a rubber material as shown in FIG. Then, a direct recording device is used in which the thickness of the developer supplied thereon is regulated by the blade 7 pressed against the rubber roll.

The developer used in the above direct recording device is
20 to 60 wt% for binder resin with an acid value of 20 KOH mg / g or less
Is mixed and pulverized after solidification to form fine toner particles, and 0.2 to 1.0 wt% of the fluidity improver relative to the amount of toner particles is externally added to the surface of the toner particles. Has been done. 5% by weight of the toner particles
The following release agents and charge control agents may be added. As the binder resin, one kind or two or more kinds of styrene resin such as polystyrene and styrene-acrylic copolymer, polyester resin, epoxy resin and phenol resin can be applied. As the colorant, one or more of pigment, dye, or magnetic powder of magnetite or ferrite can be applied. Flowability improvers include SiO ₂ , TiO ₂ ,
Al ₂ O ₃ etc. can be applied, and their primary particle size is 0.0
1 to 0.5 μm is used.

In this embodiment, styrene-acrylic resin (P520 manufactured by Sekisui Kabushiki Kaisha) or polyester resin (Mitsubishi Rayon FC433) having different acid values is used as the binder resin.
2 parts by weight and magnetite (Toda Kogyo EPT50
0) To 25 parts by weight, 2 parts by weight of polypropylene (TP-32 manufactured by Sanyo Chemical Co., Ltd.) as a release agent and 1 part by weight of a charge control agent (Kayacharge T2-N manufactured by Nippon Kayaku Co., Ltd.) were added. Dry mixing, heating, mixing, cooling, solidification, and pulverization to prepare toner particles. Further, the toner particles are classified to form a volume average particle diameter of 8.5 μm, and the electric resistance is 10
It was ¹⁴ Ωcm. Then, four kinds of fluidity improvers shown in Table 1 below are externally added to the obtained toner particles to prepare a developer, and two kinds of fluidity improvers as comparative examples are externally added and developed. The agent was created. In addition, the addition amount of the fluidity improver used in the examples and the comparative examples was slightly different as shown in Table 1. Also, as one binder resin of the comparative example,
Styrene-acrylic resin (FB1213 manufactured by Mitsubishi Rayon) was used.

As the fluidity improver of this example, (A)
Hydrophobic silica (H2000 manufactured by Wacker), (B) silicone resin particles (Trefil R925 manufactured by Toray),
(C) Polymethylmethacrylate resin particles (MP500 manufactured by Soken Chemical Co., Ltd.), (D) Hydrophobic silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) and silicone resin particles (trefil R925) were mixed in half.
In addition, as comparative examples, (E) a fluidity improver is not added externally, (F) a hydrophobic silica (Aerosil R976 manufactured by Nippon Aerosil Co., Ltd.) is used as a fluidity improver, and The added amount was different as shown in Table 1.

The apparatus was set up as follows for recording with the above-mentioned direct recording apparatus using the above-mentioned developer. The recording electrode 3 is provided with a large number of holes through which toner passes,
The diameter of each hole was 0.2 mm, and the distance between the recording electrode 3 and the sleeve 1a was set to 50 μm. The magnetic body 1b of the toner carrier is fixed, and the peripheral speed of the sleeve 1a is 300 mm /
sec, the doctor gap is set to 100 μm, and plain paper is placed between the back electrode 2 and the recording electrode 3 at 50 mm / sec.
At a speed of. Further, a voltage of + 1500V is applied to the back electrode 2, a bias voltage of -350V is applied to the recording electrode 3, and the magnetic flux density on the sleeve at the magnetic pole S ₁ position facing the doctor blade 5 is 700 gauss, and the surface of the plain paper is After continuously forming magnetic toner images, the fixing temperature is 180 ° C., the fixing pressure (linear pressure) is 1 kg / cm, and the nip width is 4.0.
The heat roll fixing was performed in mm.

Using the above developer in the direct recording apparatus set in this way, environmental conditions of temperature 20 ° C. and relative humidity 50%, environmental conditions of temperature 10 ° C. and relative humidity 20%, and temperature 3
Under the environmental conditions of 0 ° C. and 80% relative humidity, the triboelectric charge amount and the angle of repose of the developers were measured, images were obtained using the respective developers, and the fog was evaluated. Described in. The triboelectric charge amount is measured by a blow-off triboelectric charge amount measuring device (TB-200 manufactured by Toshiba Chemical Co., Ltd.).
The magnetic toner and ferrite carrier (Hitachi Metals KBN-100) were adjusted by a mold to adjust the magnetic toner concentration to 5% by weight and measured. The above electrical resistance is
In an electric field of DC4KV / cm, 10 dozen mg of the sample was filled in a Teflon (trade name) cylinder having an inner diameter of 3.05 mm,
It is a value measured by an insulation resistance meter (Model 4329A manufactured by Yokogawa Hewlett Packard) with a load of 100 gf applied.

[0021]

[Table 1]

As can be seen from Table 1, when the acid value of the binder resin corresponding to the developer of this embodiment is 20 KOH mg / g or less and the amount of the fluidity improver is 0.2 to 1.0 wt%. It can be seen that, regardless of environmental conditions such as temperature and humidity, a good image density, a repose angle of 41 ° or less, good fluidity, and a high-quality image free of background fog can be obtained. But,
In the case of the developers of Comparative Examples, it is found that the image density is lowered particularly at high temperature and high humidity, and background fog is generated (at low temperature and low humidity and high temperature and high humidity), which is not desirable. When the fluidity improver is not added, the background fog is not good even in the initial image.

[0023]

In the developer of the present invention, the binder resin has an acid value of 1
Below 5 KOH mg / g, the external additive amount of fluidity improver is 0.2-
Since it is 1.0 part by weight, it has moisture resistance, and when an image is directly formed on a recording device, the fluidity of the developer is good, so that the developer is transferred from the toner carrier to the recording electrodes in a matrix form. Therefore, it is possible to reliably and accurately hit the recording medium, and a good image can be obtained even when the environmental conditions such as temperature and humidity are bad.

[Brief description of drawings]

FIG. 1 is a schematic view of a direct recording device using the developer of the present invention.

FIG. 2 is a schematic view of another configuration of a direct recording device using the developer of the present invention.

FIG. 3 is a schematic view of still another direct recording device using the developer of the present invention.

[Explanation of symbols]

 1 toner carrier 2 back electrode 3 recording electrode 5 doctor blade 7 blade

Claims (4)

[Claims] 1. A back electrode is arranged so as to face the toner carrier, and a matrix-shaped recording electrode is arranged between the toner carrier and the back electrode, and a voltage is applied to the recording electrode in accordance with a state of voltage application. A developer used in a direct recording device in which toner is scattered from a toner carrier to a recording body between a recording electrode and a back electrode, and a binder resin having an acid value of 15 KOH mg / g or less and 5 to 60 wt. % Of the colorant is added to the toner particles, and 0.2 to 1.0 parts by weight of the fluidity improver is added to 100 parts by weight of the toner particles. Agent. 2. The binder resin is polystyrene, styrene-
The developer according to claim 1, comprising one or more of styrene resins such as acrylic copolymers, polyester resins, epoxy resins, and phenol resins. 3. The developer according to claim 1, wherein the colorant is one or more of a pigment, a dye, or magnetic powder of magnetite or ferrite. 4. The fluidity improver comprises SiO ₂ , TiO ₂ ,
Made of Al ₂ O ₃ etc. and has a primary particle size of 0.01 to 0.5
The developer according to claim 1, 2 or 3, wherein the developer has a thickness of μm.