JPH068965B2 - Development method - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an electrophotographic apparatus or an electrostatic recording apparatus,
The present invention relates to a developing method for visualizing an electrostatic latent image formed on a photoconductor or a dielectric.

[Technical background of the invention and its problems] In order to visualize an electrostatic latent image formed on an electrostatic image holding member from a photoconductor, a dielectric or the like in an electrophotographic apparatus or an electrostatic recording apparatus. Conventionally, a two-component developing method including a toner and a carrier has been widely used as a developing method with good image quality.

However, while this two-component developing method has the above advantages, it has the following drawbacks.

The toner receives a triboelectric charge due to mutual friction between the toner and the carrier, but if it is used for a long period of time, the carrier surface is contaminated by the composition of the toner, and it becomes impossible to acquire a sufficient charge.

It is necessary to adjust the mixing ratio of the toner and the carrier within a predetermined range, but if it is used for a long period of time, the mixing ratio fluctuates and deviates from the predetermined range, and good development cannot be obtained.

In general, iron powder or glass beads whose surface is oxidized is often used as a carrier, but the carrier mechanically damages the surface of the photoconductor and shortens the life.

Therefore, various developing methods using a single-component toner composed of only toner have been proposed. Above all,
Many developing methods using a toner called magnetic toner containing magnetic powder have been proposed. Among them, those based on US Pat. Nos. 3,909,258 and 4121931 have been put into practical use. However, these methods also have the following drawbacks. That is, since a magnetic toner having a relatively low specific resistance is used, it is difficult to electrostatically transfer the developed image on the electrostatic latent image to a supporting member such as plain paper. I can't get a transcription.

Since the toner contains a large amount of magnetic powder, a color toner other than dark color cannot be obtained.

Therefore, recently, a developing method using a one-component toner which does not contain magnetic powder and has a large specific resistance, which has been conventionally used in a two-component developing method, has been proposed. Examples of such a developing method include a touchdown method and an impression method described in, for example, U.S. Patent Nos. 2895847, 3152012, JP-B-41-9475, 45-2877, and 54-3624. , Those based on the jumping method.

However, when the toner used in the two-component developing method is used in such a one-component developing method, various problems occur as described below.

First, when such a method is used, there is a problem that the amount of triboelectric charging is insufficient.

Generally, in one-component development, the toner is charged efficiently with the toner carrier and in a very short time, and is sufficient to visualize the electrostatic latent image formed on the photosensitive drum or the dielectric without contact. It is necessary to obtain the charge amount (for example, about 0.5 to 15 μC / g when a selenium photosensitive drum is used).

However, there is a problem that the triboelectrification between the toner and the toner carrier used in the conventional two-component developing method cannot obtain a sufficient amount of charge for visualizing.

That is, in the conventional two-component developing method, triboelectrification of the toner and the carrier is carried out for a sufficient time to obtain the charge amount required to form a visible image. The friction charging time is short with
That is, the amount of charge necessary for visualizing cannot be obtained.

Secondly, it is necessary to apply the toner very thinly and evenly on the surface of the toner carrier, but the toner used in the two-component developing method has a problem that it is difficult to form such a thin layer. An example of the process of forming this thin layer will be described with reference to the schematic view of the drawing. As shown in the figure, the elastic blade 2 is pressed against the toner carrier 1 at a pressure of 100 g / cm to 2500 g / cm, and the toner 4 in the toner container 3 is conveyed by the rotation of the toner carrier 1 while the toner is moved by the elastic blade 2. It is applied very thinly and evenly on the surface of the carrier 1. Therefore, the toner carrier 1 is required to have good fluidity and aggregation resistance. However, there is a problem that the toner 4 in the toner container 3 often becomes cohesive and soul-like in the process of being conveyed by the rotation of the toner carrying resistance 1, and the toner is not applied to the surface of the toner carrier 1. there were.

In addition, the toner 4 conveyed by the toner carrier 1
Due to the surface pressure between the elastic blade 2 and the toner carrier 1, abruptly high pressure is applied to these contact portions, so that frictional heat is generated and the toner 4 is softened and the surface of the toner carrier 1 is exposed. There is a problem in that the toner adheres and the toner is not applied evenly and thinly.

Further, when the softening point becomes high, the fixing temperature becomes high, and there is a problem that it is difficult to use it in a normal office copying machine.

Third, pigments are generally negatively charged, and most of them are negatively charged especially in carbon black. Therefore, when they are used as positively charged toners, they are not charged between toner particles, between toner and toner carrier, and toner. There is a problem in that, between the elastic blades and the like, charges generated on the surface of the toner particles cause opposite polarities, and problems such as development fog and toner scattering are likely to occur.

These obstacles appear as a remarkable phenomenon when a large number of copies are piled up. Therefore, the conventional developing method using a one-component toner is not suitable as a copying machine.

[Object of the Invention] The present invention has been made to solve these problems.
By solving the various problems mentioned above, a thin layer is uniformly formed on the toner carrier, the triboelectric charge amount is stable, the triboelectric charge amount distribution is sharp and uniform, and development fog does not occur, and an electrostatic latent image is formed. It is an object of the present invention to provide a developing method using a positively-charged, non-magnetic single-component toner that can faithfully visualize a high-quality electrostatic latent image without causing toner scattering around the edges of the latent image. To do.

SUMMARY OF THE INVENTION The present invention is an electrostatic image holder that holds an electrostatic latent image on its surface,
A non-magnetic one-component toner is placed on the surface of the toner carrier with a constant distance, the non-magnetic one-component toner is applied on the toner carrier, and the toner is applied to the electrostatic image carrier. In the developing method of visualizing the electrostatic latent image on the surface of the electrostatic image carrier by moving to, the non-magnetic one-component toner, the glass transition point is a monomer having an amino group as a constituent element is 50 ℃ or more, By using a positively charged non-magnetic one-component toner containing a pigment whose surface is treated with a silane coupling agent having an amino group and a charge control agent in a copolymer having a softening point of 110 to 160 ° C., a uniform toner is obtained. A thin layer is formed on the carrier, the triboelectric charge amount is stable, the triboelectric charge amount distribution is sharp and uniform, development fog does not occur, the electrostatic latent image is faithful and the toner around the edge of the latent image is formed. Electrostatic latent image without splattering It is obtained by allowing the can visualized in high quality.

The copolymer used in the positively charged non-magnetic one-component toner of the present invention has a glass transition point of 50 ° C or higher and a softening point of 110 ° C to 160 ° C.
Among these, a copolymer of styrene-acrylic copolymer or styrene-methacrylic copolymer and a monomer having an amino group is particularly suitable.

As the acrylic component or methacrylic component used in the synthesis of the copolymer, acrylic acid and methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate,
Acrylic esters such as isobutyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, and methacrylic acid and methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate Conventionally known acrylic acid and its derivatives such as methacrylic acid esters such as octyl methacrylate, methacrylic acid and its derivatives can all be used.

A methacrylic acid derivative represented by the following general formula is suitable as the amino group-containing monomer used in the synthesis of the above copolymer.

(However, R ₁ , R ₂ , R ₃ , and R ₄ are alkyl groups having 1 to 8 carbon atoms) Examples of the monomer having an amino group represented by the above general formula include 2-dimethylamino-2-methyl. Propyl methacrylate, 2-dimethylamino-2-ethylbutyl methacrylate, 2-dimethylamino-2-propylhexyl methacrylate, 2-dimethylamino-2-methylpropyl methacrylate, 2-diethylamino-2
-Ethylbutyl methacrylate, 2-diethylamino-
2-Propylhexyl methacrylate and the like are exemplified.

As a polymerization initiator for copolymerizing a monomer having an amino group with a styrene-acrylic copolymer or a styrene-methacrylic copolymer, azobis (isobutyronitrile), azobis2- (2-naphthyl) is used. A nitrile initiator represented by propyronitrile or the like can be used.

As the silane coupling agent having an amino group used in the present invention, a silane compound represented by the following general formula is suitable.

Or (Wherein _{R 1 'is, -H, -CH 3, -C 2} H 5, -CH 2 CH 2 O
H, R ₂ ′ is — (CH ₂ ) _n −, -CO-, R ₃ ′ is —CH ₃ , —OCH ₃ , —OC ₂ H ₅ , and n is 1 to 4
Examples of the silane compound represented by the above general formula include, for example, H ₂ N (CH ₂ ) ₃ Si (OCH ₃ ) ₃ , H ₂ N (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ , _{H 2 N (CH 2) 3} Si (CH 3) OCH 3) 2, H 2 N (CH 2) 3 Si (CH 3) 2 (OC 2 H 5), H 2 N (CH 2) 2 NH (CH ₂ ) ₃ Si (OCH ₃ ) ₃ , H ₂ N (CH ₂ ) ₂ NH (CH ₂ ) ₃ CH ₃ Si (OCH ₃ ) ₂ , H ₂ N (CH ₂ ) ₂ NH (CH ₂ ) ₃ Si (CH ₃ )) (OCH ₃ ) ₂ , H ₂ NCO (NH (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ , (H ₅ C ₂ ) ₂ N (CH ₂ ) ₃ Si (OCH ₃ ) ₃ , _{-CH 2 Si (OCH 2) 3} , (HOCH ₂ CH ₂ ) ₂ N (CH ₂ ) ₃ Si (OCH ₃ ) _{3 and the} like are exemplified.

These silane coupling agents are used alone or in a mixture of two or more.

Examples of the pigment used in the present invention include carbon black, Fast Yellow G, Benzidine Yellow, Pigment Yellow, India First, Orange, Irgadine Red, Carmine FB, Permanent Poldo FRR, Pigment Orange R, Resole Red 2G, Known pigments such as Lake Red C, Rhodamine FB, Rhodamine B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green, and Quinacridone can be used.

The positively-charged non-magnetic single-component toner of the present invention, in order to improve the fluidity and aggregation resistance of the toner, if necessary,
Hydrophobicized colloidal fine particles having the same polarity as the toner, such as colloidal silica, may be added in an amount not affecting the toner charge amount, for example, about 0.05 to 2 parts by weight.

Next, a developing process to which the present invention is applied will be described with reference to the drawings.

As shown, the electrostatic image carrier 5 is rotated in the direction of the arrow. In the developing section, the toner carrier 1 rotates so as to move in the same direction as the surface of the electrostatic image carrier 5, and the one-component non-magnetic toner 4 sent from the toner container 3 is pressed onto the toner carrier 1. The elastic blade 2 is applied thinly and uniformly on the toner carrier, and friction between the toner carrier and the elastic blade and the toner imparts a charge having a polarity opposite to the electrostatic image charge to the toner particles.

At this time, in the developing section, a DC bias or an AC bias, or a DC and AC weight bias may be applied between the toner carrier 1 and the surface of the electrostatic image carrier 5.

[Advantage of the Invention] According to the developing method of the present invention configured as described above, the developing system in which the triboelectric charge amount between the toner and the elastic blade or between the toner and the toner carrier is stable and is used It is possible to control the charge amount suitable for the above, and therefore, the development fog and the toner scattering around the edge of the latent image, which could not be solved sufficiently in the past, are eliminated, and a high image density can be obtained.

Furthermore, even when the toner is used continuously for a long period of time, the initial characteristics can be maintained, high-quality images can be used for a long period of time, and the friction of the toner when used under high-temperature high-humidity or low-temperature low-humidity environmental conditions. The charge amount is stable, hardly changes with room temperature and normal humidity, there is no fog in the development and the image density is not reduced, the development can be performed faithfully to the latent image, and the transfer efficiency is excellent.

Embodiments of the Invention Next, embodiments of the present invention will be described. The parts in the following examples are parts by weight.

Example 1 [Synthesis of Copolymer Having Amino Group] Styrene 85 parts n-Butylmethacrylate 10 parts (Diethylamino) ethylmethacrylate 5 parts Azobisisobutyronitrile 8 parts The above mixture was stirred at 65 ° C. for 6 hours to prepare styrene. An n-butyl methacrylate (diethylamino) ethyl methacrylate copolymer was obtained.

[Preparation of pigment] 10 parts carbon black (specific surface area 134 m ² / g) N-β- (aminoethyl) -γ-aminopropyl-trimethoxysilane 4 parts (covering area 353 m ² / g) water 80 parts The above mixture After stirring at room temperature for 5 hours, filtration and washing with water were repeated several times, followed by drying at 100 ° C. for 8 hours, vacuum drying, and crushing into fine particles with a crusher. The carbon black treated with the silane coupling agent having an amino group was measured for its tripoelectric charge by the blow-off method (manufactured by Toshiba Chemical Co., Ltd.) and found to be plus 32.5 μc / g. On the other hand, the tripoelectric charge similarly measured for untreated carbon black is
It was minus 25.0 μc / g.

Next, the above-mentioned styrene-n.butylmethacrylate-
92 parts of (diethylamino) ethyl methacrylate copolymer, 5 parts of the above carbon black, and 3 parts of a nigrosine-based positive charge control agent (N-09: manufactured by Orient Chemical Co., Ltd.) were premixed in a ball mill for about 2 hours and then added. About 1 with a pressure kneader
Kneaded for hours. Next, after cooling this kneaded product, it was roughly pulverized by a hammer mill and finely pulverized by a jet mill, and the pulverized product was classified by an air classification method to obtain a toner of 5 to 25 μm.

Thereafter, 100 parts by weight of this toner and 0.5 parts by weight of positively charged colloidal fine particles (RA-200: manufactured by Nippon Aerosil Co., Ltd.) are mixed by a ball mill and adhered to the surface of the colloidal fine particles to obtain a 50% weight average. A one-component non-magnetic toner having a particle size of 12.4 μm was obtained.

This tripo charge by the blow-off method is plus 32.3 μc
/ G. Next, the OPC photoreceptor of the negative latent image is used in a commercially available copying machine (trade name: Rhodry 3301 manufactured by Toshiba Corp.), and the above-mentioned one-component non-magnetic toner is supplied to the apparatus shown in the figure to develop the image, thereby causing development fog. A clear image was obtained.

Further, even under a high temperature and high humidity (30 ° C., 85% RH) environment, there was no development fog and there was no reduction in image density, and a clear image with good transfer efficiency was obtained.

Further, a clear image with high density was obtained even in an environment of low temperature and low humidity (5 ° C., 10% RH).

Further, when fixing with a heat roll fixing device, fixing started at 170 ° C, and offset did not occur even at 220 ° C.

Comparative Example 1 The procedure of Example 1 was repeated, except that a styrene-n-butyl methacrylate copolymer was used instead of the styrene-n-butyl methacrylate- (diethylamino) ethyl metacopolymer of Example 1. No image was obtained. The tripoelectric charge measured by the blow-off method was -18.5 μc / g.

Comparative Example 2 The procedure of Example 1 was repeated except that untreated carbon black was used in place of the carbon black treated with the silane coupling agent having an amino group of Example 1, and a large amount of development fog occurred. There were also many scattering around the edge.

Example 2 Instead of the styrene-n-butyl methacrylate- (diethylamino) methacrylate copolymer of Example 1, styrene-n-butylmethacrylate- (dimethylamino) was used.
Example 1 except that a methacrylate copolymer was used
When carried out in the same manner as above, a clear image was obtained with no development fog and no toner scattering around the edge of the latent image.

The 50% weight average particle diameter of this toner was 12.8 μm, and the tripoelectric charge was plus 29.8 μc / g.

Example 3 As the silane coupling agent having an amino group of Example 1, N-β- (aminoethyl) -γ-aminopropyl-
When development was performed in the same manner as in Example 1 except that γ-aminopropyltriethoxysilane was used instead of trimethoxysilane, a good visible image without development fog was obtained.

The toner had a 50% weight average particle diameter of 11.5 μm and a tripoelectric charge of plus 31.5 μc / g.

[Brief description of drawings]

The drawing is a drawing schematically showing a main part of a developing device of a one-component developing method. 1 ... toner carrier 2 ... elastic blade 3 ... toner container 4 ... toner 5 ... electrostatic image carrier

Claims (5)

[Claims] 1. An electrostatic image carrier that holds an electrostatic latent image on the surface and a toner carrier that carries a non-magnetic one-component toner on the surface are arranged at a constant interval, and the non-magnetic one-component toner is used. In a developing method in which toner is applied onto the toner carrier and the toner is transferred to the electrostatic image carrier to visualize the electrostatic latent image on the surface of the electrostatic image carrier, the non-magnetic one-component toner is Copolymers with a monomer having an amino group as a constituent, a glass transition point of 50 ° C or higher, and a softening point of 110 to 160 ° C, a pigment surface-treated with a silane coupling agent having an amino group, and charge control A positively charging non-magnetic one-component toner containing a developing agent. 2. The monomer according to claim 1, wherein the monomer having an amino group as a constituent element of the copolymer is an aminoacrylic monomer or an aminomethacryl monomer. The developing method described. 3. The silane coupling agent having an amino group is represented by the general formula: Or (Wherein _{R 1 'is, -H, -CH 3, -C 2} H 5, -CH 2 CH 2 O
H, R ₂ ′ is — (CH ₂ ) _n −, -CO-, The developing method according to claim 1, wherein R ₃ ′ is represented by —CH ₃ , —OCH ₃ , —OC ₂ H ₅ , and n is an integer of 1 to 4, respectively. 4. The developing method according to claim 1, wherein the copolymer is a styrene-acrylic copolymer or a styrene-methacrylic copolymer. 5. The developing method according to claim 1, wherein the positively charged non-magnetic one-component toner contains 0.05 to 2 parts by weight of colloidal silica.