JPS63201667A - Developing agent for electrostatic charge image development - Google Patents

Abstract

PURPOSE:To stabilize the triboelectrification quantity of the toner, and to make the triboelectrification distribution of the toner uniform, by incorporating a positive electrostatic charge toner contg. a binder resin, a coloring agent and a positive electrostatic charge controller having a specified unit structure, and the fine powder of a positive electrostatic charged silica in the titled developing agent. CONSTITUTION:The titled agent comprises the positive electrostatic charge toner contg. the binding resin, the coloring agent and the compd. having the unit structure shown by formula I, and the fine powder of the positive electrostatic charge. In the fine powder of the positive electrostatic charge. In the formula, R<1> and R<2> are each a monovalent org. group which is the same or the different with each other, M is group III elements of the periodic table, X is a monovalent group. The Sn-O-M structure is supposed to have the important ability of the positive electrostatic charge controller. In the formula, R<1> and R<2> are each alkyl or a cycloalkyl group, etc., M is preferably boron or aluminium, X is preferably hydroxyl, alkyl or aryl group. Thus, the image having the high quality is obtd. by charging said image to the positive with uniform and strong, and by making a negative electrostatic charge image visible, or by making the positive electrostatic charge image visible by a reversal development.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a developer for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. More specifically, it relates to a developer for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. In photographic development methods, positively charged toner and positively charged toner that are uniformly and strongly positively charged to visualize a negative electrostatic charge image or to visualize a positive electrostatic charge image by reversal development to produce a high quality image. The present invention relates to a developer containing fine silica powder.

(Prior Art) Conventionally, as an electrophotographic method, U.S. Patent No. 2,297.6
Specification No. 91, Japanese Patent Publication No. 42-23910 (U.S. Patent No. 3,666.363), Japanese Patent Publication No. 43-24
Although many methods are known, such as No. 748 (U.S. Pat. No. 4,071,361), they generally utilize a photoconductive substance to create an electrical latent image on a photoreceptor by various means. , and then convert the latent image into developing powder (hereinafter referred to as toner).
After the toner image is transferred to a transfer material such as paper as necessary, it is fixed by heating pressure, a pressurized heat roller, solvent vapor, etc. to obtain a copy. In addition, if there is a step of transferring a toner image, usually
A step is provided to remove residual toner on the photoreceptor.

Development methods for visualizing electrical latent images using toner include, for example, the magnetic brush method described in U.S. Pat. No. 2,874,063, and the magnetic brush method described in U.S. Pat. Cascade development method and 2,221.7
Powder cloud method described in US Pat. No. 76, U.S. Pat.
．． A method using conductive magnetic toner described in Japanese Patent No. 909.258 is known.

Conventionally, toners used in these development methods are fine powders in which dyes and pigments are dispersed in natural or synthetic resins. Finely pulverized particles of about 1 to 30 microns are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used. In the case of a system using a so-called two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder.

Positive charge control agents used in such dry developing toners generally include, for example, salts of quaternary ammonium compounds and organic dyes, particularly basic dyes, such as nigrosine base, and nigrosine is often used as a positive charge control agent. It is used as.

These are usually added to a thermoplastic resin, heat-melted and dispersed, and then finely pulverized and adjusted to an appropriate particle size as necessary before use.

However, these charge control agents tend to deteriorate their charge control properties due to mechanical shock, friction, changes in temperature and humidity conditions, etc. Therefore, it is difficult to use toner containing these charge control agents in copying machines. If the toner is developed using the same method, the toner may deteriorate during durability as the number of copies increases.

Furthermore, since it is extremely difficult to uniformly disperse these charge control agents in a thermoplastic resin, there is a problem in that there is a difference in the amount of frictional charge between toner particles obtained by crushing them. There is. For this reason, various methods have been used to achieve more uniform dispersion. For example, basic nigrosine dyes are used by forming salts with higher fatty acids in order to improve their compatibility with thermoplastic resins, but unreacted fatty acids or salt dispersion products often remain on the toner surface. When exposed, it contaminates the carrier or toner carrier, causing a decrease in toner fluidity, fogging, and a decrease in image density. Alternatively, in order to improve the dispersion of these charge control agents into the resin,
Although a method of mechanically pulverizing and mixing the charge control agent powder and resin powder and then hot melting and kneading has been used, the inherent poor dispersion cannot be avoided and the charge uniformity is still sufficient for practical use. The reality is that this has not been achieved.

In addition, amino groups can be introduced into the binder resin by copolymerizing or graft polymerizing a positively chargeable polymer such as dimethylaminoethyl methacrylate, and the binder resin itself can be positively chargeable. Attempts have also been made to uniformly charge the toner. However, the positive chargeability of the binder resin described above is still not stable enough, and the frictional force between toner particles, between toner and carrier, or between toner and toner carriers such as sleeves It varies greatly depending on the size and friction probability, and it is extremely difficult to always give a constant and stable positive charge to the toner. Copied images obtained with toner having unstable positive chargeability and having only a low frictional charge amount are prone to fogging and scattering.

On the other hand, if an excessive amount of triboelectric charge is retained, the image becomes rough and it becomes impossible to obtain an image with low density.

As a method of obtaining a developer with positive charge control property,
There is a proposal in Publication No.-22447.

This is a method in which a metal oxide powder treated with aminosilane is contained as a component of the developer, but after a detailed study of this method, various aminosilane compounds were used, such as colloidal silica, alumina, dioxide, etc. Titanium, zinc oxide.

When iron oxide, γ-ferrite, magnesium oxide, etc. are processed and a developer is obtained according to the examples described in the specification, it is clear that there are some problems with any combination. became. That is, images cannot be obtained under environmental conditions of high temperature and high humidity, resulting in a decrease in image density, white spots, fogging, etc. In addition, with many developers, the image density gradually decreases as the number of copies is increased, resulting in fogging.

Roughness and reverse fog increase significantly.

On the other hand, other methods for obtaining a developer with positive charge control properties are disclosed in JP-A-59-34539 and JP-A-59-20106.
This is proposed in Publication No. 3.

These methods involve treating fine silicic acid powder, which is a type of metal oxide, with silicone oil having an amine in its side chain. A developer having improved development properties is obtained. However, there is a long-awaited need for a developer with further improved development characteristics.

Recently, as the demand for improved image quality has increased, image forming apparatuses such as electrophotographic printers that use digital image signals are being used.

When using conventional positively chargeable toner, the non-uniformity of charge that tends to occur on the surface of toner particles between toner particles, between toner and carrier, or between toner and toner carriers such as sleeves is It has become clear that problems arise particularly when developing electrostatic latent images formed using digital image signals, and a developer having a more uniform charge has been desired. In other words, when the image signal is a digital signal, the latent image is formed by a collection of dots with a constant potential, and solid areas,
The halftone part and the light part are each expressed by changing the density of dots. Therefore, any part is 2
In the case of a high value, basically, electrostatic latent images of approximately the same potential are formed. Furthermore, recently there has been a growing demand for improved image quality, and it has become necessary to improve gradation reproducibility by using a three-value or four-value multi-value dither method instead of the black-and-white binary dither method described above. This multi-level dithering method is useful when removing false contours that tend to occur in highlight areas, or when simultaneously reproducing an image containing a mixture of halftones and line images. This technology is also essential when reducing the size and improving resolution.

First, we introduce the concept of dither matrix that can be used in multilevel dither method.
This will be explained with reference to FIGS. (a) and (b). Figure 1 (
a) is a 2×2 ternary dither matrix, and the area 31. S2. S3 represents three density levels of white, gray, and black, respectively. Also, Fig. 1(b) shows 2x2
is a four-valued dither matrix of area Sl.

52, S3. S4 is white and light gray, respectively.

It represents four density levels: dark gray and black. The dot size is, for example, 16 dots/mm.

Figures 2(a), (b) and 3(a).

(b) shows the exposure intensity distribution when performing ternary recording in an optical scanning type electrophotographic printer.
a) and the corresponding potential distribution of the electrostatic latent image (b)
), which represents FIG. 3(b). Figure 2(a)
The broken line in FIG. 3(a) represents the signal output for outputting a light beam for forming a multivalued latent image.
Figure (a) shows that the first
This method obtains a gray level (hereinafter referred to as M level) corresponding to 52 in FIG. 5A and a black level (hereinafter referred to as H level) corresponding to S. For example, the M level can be obtained with a laser output that is 1/2 that of the H level. Figure 3 (
A) is a method for obtaining the M level and H level by pulse width modulation that controls the laser output time.

This can be obtained, for example, by setting the pulse width of the M level to 1/2 that of the H level. Figure 2(a)′Et and 3rd
The potential distribution of a latent image created by a light beam having the exposure intensity distribution shown in Figure (a) is as shown in Figures 2 (b) and 3 (b), and especially the pulse width modulation shown in Figure 3 (b). The M level is 1 (&contrast is H due to the decrease in MTF of the latent image)
It tends to be smaller than the level. Therefore, this M
The image density of the level is M
The gray level is almost the same as the image density after level development.

Figure 4 shows the development characteristics (Vs-
2(b) and 3(b).
) to reproduce the M and H level latent images (respective potential contrasts are represented by
A Vs-Dp characteristic (indicated by the solid line ■ in the figure) with a large slope of image density relative to image potential is required. however,
When conventional toners or developers for developing analog latent images are used, they often tend to exhibit development characteristics as shown by the solid line (3), resulting in tank problems. Further, when developing a latent image expressed by the density of digital dots, more precise control of this Vs-Dp convex curve is required than in the case of a conventional analog latent image. One is that to develop a digital latent image, the slope of the Vs-Dp convex curve t! - (gamma) needs to be made larger than before, and it is also necessary to control this slope so that it does not fluctuate. The non-uniformity of charge that occurs in toners using conventional charge control agents becomes an obstacle to increasing the slope of the Vs-Dp convex curve, and tends to cause fluctuations. H level dots are not reproduced at a sufficiently high density, or
Either the density difference between the level and the M level cannot be sufficiently reproduced, or the potential at the edge of the dot is lower than that at the center, as shown in Figure 21 and Figure 3, so the image at the edge of the dot is Problems such as poor sharpness occur, resulting in a defective image with low image density, lack of sharpness, and low resolution. In addition, this non-uniformity of charge can occur when copying is repeated a large number of times or due to fluctuations in the usage environment.
-Dp Convex curve fluctuation occurs, causing the above-mentioned problems.

In addition, OPC photoreceptors have recently become more durable, and positively chargeable toners are being applied to machines that are faster than conventional ones. In this case, a positively chargeable toner or a developer containing the same is required, which has high durability and can withstand a larger number of copies than conventional ones, not only for developing digital latent images but also for developing analog latent images. Ru.

Image quality such as ground blur, reverse fog, and roughness tends to deteriorate in direct proportion to an increase in process speed, and this is particularly noticeable in reverse fog. This development is thought to be due to the fact that as the process speed increases, the opportunities for rubbing between the toner and the toner carrier become smaller and shorter, making it impossible for the toner to obtain sufficient and uniform charging. .

In addition, in high-end machines, after the image formed on the photoreceptor drum is transferred onto transfer paper, a method that uses static electricity is often used in the process of separating the drum and paper. A new process (post-charging) is added in which the toner is uniformly charged with the same sign as the developer before the toner is transferred. In such an image forming process, if toner is present as fog on the drum,
In the conventional image forming process, things that were not transferred onto the paper are transferred onto the paper due to the addition of a new charging process, which appears as fog in the final image. It is necessary to control the amount of frictional charge more sharply than with conventional toners, and it is currently extremely difficult to use conventional toners as they are in copying machines that have a post-charging process.

(Problems to be Solved by the Invention) An object of the present invention is to stabilize the amount of triboelectric charge between toner particles, between a toner and a carrier, or between a toner and a toner carrier such as a sleeve in the case of -component development. It is an object of the present invention to provide a developer containing a positively charged toner which has a sharp and uniform triboelectric charge amount distribution and can control the charge amount suitable for the developing system used.

Another objective is to create a toner that can be developed faithfully to a digital latent image, that is, the slope of the Vs-Dp curve during development is large, and it is possible to increase the density difference between dots, and the edges of the dots can be An object of the present invention is to provide a developer containing a toner that reproduces sharp images.

Still another object is to provide a developer containing a toner that maintains its initial characteristics even when the toner is used continuously over a long period of time, and does not exhibit fluctuations in the Vs-Dp curve.

Still another object is to provide a developer containing toner that causes less fog and reversal fog even in an image forming process including post-charging.

Still another object is to provide a developer containing toner that reproduces stable images that are not affected by changes in temperature and humidity.

Still another object is to provide a developer containing a toner with excellent storage stability that maintains its initial characteristics even during long-term storage.

Yet another object is to provide a developer containing bright chromatic toners.

[Means and effects for solving the problems] In other words, the present invention is characterized in that at least a binder resin (1), a colorant, and a positively charged compound containing a unit structure represented by the following general formula (1) are used. The present invention is a developer for electrostatic image phenomenon, which is composed of a positive chargeable toner and a positively chargeable silica fine powder.

R' (R2)SnO(MX)O(I) (However, R1
, R2 are monovalent organic groups and represent the same or different groups, M represents an element of the In group in the periodic table, and X represents a monovalent group. ) Sn-0-M in the compound of the present invention
It is presumed that the structure plays an important role as a positive charge control agent.

R' and R2 in formula (I) need to be organic groups in order to improve affinity with the binder resin.

Examples of the organic group include an alkyl group, a cyclic alkyl group, an aryl group, an aralkyl group, an acyl group, an alkenyl group, an alkynyl group, or a group consisting of a derivative having these groups as a basic skeleton.

The organic group may be substituted with a substituent such as a halogen element, a hydroxyl group, or a carboxyl group to the extent that it does not adversely affect charge controllability, and R1 and R2 are the same or different groups, and R1 and R2 are They may be combined to form a ring structure.

Considering ease of production, the organic group preferably has 1 to 20 carbon atoms. In addition, when the organic group is an alkyl group, an alkyl group having 1 to 8 carbon atoms is particularly preferable.More specifically, R1 and R2 are methyl, ethyl, n-butyl, octyl, and lauryl groups. Alkyl groups such as; cyclic alkyl groups such as cyclohexyl and cyclopentyl; aryl groups such as phenyl, naphthyl and anthryl; aralkyl groups such as benzyl and phenylethyl; acyl groups such as acetyl and benzoyl; Examples include alkenyl groups such as vinyl, allyl, and isopropenyl; alkynyl groups such as ethynyl and 2-propynyl, which may be substituted with the above-mentioned substituents.

Next, M in formula (1) represents an element of group III in the periodic table. Among the elements of group III, boron and aluminum are preferable, and boron is particularly preferable.

X in formula (1) represents a -valent group, and can be virtually any group as long as it can be bonded or arranged to satisfy the valence of M and does not adversely affect chargeability. It may be. Preferred X is a hydroxyl group, an alkyl group or an aryl group.

Examples of compounds having formula (1) as a unit structure include the following, but these are basic structures, and in reality, they may be multimers of several of them.

(1)(C4He +23 no (B-OH)OHs (4) (<E>÷2SnO(B-OH) 0(5)(
○-CH2+z SnO(Al1-OH) 0(6)
(NH2-C4H6+ 2 S no (B-C4H
e) 0(7)(CH2=CH+2S no (B-
Of()0(8)(C2H8−○→2SnO(AJl−
OH) 0(10) (H2$ 5nO(Aj!-0H)
0"-1111-1 (11) (CHE-C-CH2÷2 SnO(AJ
l-OH) 0(12) (CH30-()÷2SnO
(B-OH) 0 Furthermore, as the silica fine powder constituting a component of the developer in the present invention, silica fine powder manufactured by a dry method or a wet method can be used.

The dry method mentioned here is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halide compound. For example, silicon tetrachloride gas oxygen.

This method utilizes a thermal decomposition oxidation reaction in hydrogen, and the basic reaction formula is as follows.

S i el14+2) (2+02→S i O2+4
HC1 Also, in this manufacturing process, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halide compounds such as aluminum chloride or titanium chloride together with a silicon halide compound, and these can also be used. include.

Commercially available silica fine powder produced by vapor phase oxidation of a silicon halogen compound used in the present invention includes, for example, those commercially available under the following trade names.

AERO3IL 130 (Japan Aerosil Co., Ltd.) 20
0X50 T600 0X80 0X170 0K84 Ca-0-3iL M
75 (CABOT Co, Ltd.) MS
-7MS-5 H-5 Wacker HDK N 20
V 1 5 (WACKER-CHEMIE
GMBH) N20ED-CFine 5ili
ca (Dow Corning Co., Ltd.) Fransol (Fransi 1 Company) On the other hand, various conventionally known methods can be applied to the method of producing the silica fine powder used in the present invention by a wet method.

For example, the decomposition of sodium silicate with an acid can be expressed using a general reaction formula (the reaction formula is omitted below): Na20''XS i O2+HCJ!+H20=S
i02 ” nH20+Na (J! Others, decomposition of sodium silicate with ammonia salts or alkali salts, method of generating alkaline earth metal silicate from sodium silicate and then decomposing it with acid to produce silicic acid, sodium silicate There are methods such as converting the solution into silicic acid using an ion exchange resin, and methods using natural silicic acid or silicate.

As the silica fine powder referred to herein, any of anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate can be used.

Commercially available fine silicic acid powders synthesized by a wet method include those sold under the following trade names, for example.

Carplex Shionogi & Co., Ltd. Neve Seal Nippon Silica Toxeal,
Fine Seal Tokuyama Soda Vita Seal
Multi-wooden fertilizer JILTON, Silnetx Mizusawa Kagaku Starsil
Kamishima Chemical Himezil
Ehime Pharmaceutical Thyroid Fuji Davison Chemical H3-3il (Hiseal) Pittsburgh Plate Glass
Co.

(Pittsburgh Plate Glass) Durosil Ultrasi
l (Ultra Seal) Fillstoff-G
esellschaft Marquart Mano
sil Hardman and Ho1den HoeSCh Chemische Fabrik Hoesch K
-G (Hiemitsussie Fabrik Herash) Sil
-3tone Stoner
Rubber Co.

(Stoner rubber) Nalco (Nalco) Nalco Chem, Co.

(Narco Chemical) Quso (shoes) Philadelphia Quartz Co.

(Philadelphia Quartz) Imail (Imcil) 111inois Minerals Co.

(Illinois Mineral) Calcium 5ilikat (Calcium Silicate) Chemische Fabrik Hoe
sch K-G Calsil FLillstoff-Gesellschaft M
arquart Fortafil Imperial Chemical In
industries Ltd.

(Imperial Chemical Industries) Mic
local (Microcal) Joseph Crosfield &5ons
Ltd.

(Jiecef Crossfield & Sons) Ma
nosil Hardman and Ho1den Vulkasil Farben
Bryer, A.G.

(Falpenfabriken Bayer) Tufkni
t (tough knit) Durham Chemicals Ltd.

(Doulham Chemicals) Silmos Shiraishi Kogyo Starex Kamishima Kagaku Fricosil
Among the silica fine powders mentioned above, BE
Specific surface area due to nitrogen adsorption measured by T method is 30m27g
or more (particularly 50 to 400 m''/g) gives good results.

Conventionally, it is known that fine silica powder produced by vapor phase oxidation of a silicon halide compound is added to a developer. However, even in a developer containing a dye or the like that has positive charge control properties, when such silica is added, the chargeability changes to negative, making it difficult to visualize a negative electrostatic charge image or reverse develop a positive electrostatic charge image. It was unsuitable for visualization.

As a method for obtaining positively chargeable silica fine powder, the above-mentioned untreated fine silica powder is treated with a silicone oil having an organo group having at least one nitrogen atom in its side chain, or a nitrogen-containing silane coupling agent is used. There are two ways to process this:

In the present invention, positively charged silica refers to silica that has a positive triboelectric charge when measured by a blow-off method.

As the silicone oil having a nitrogen atom in the side chain used in the treatment of silica fine powder, a silicone oil having at least a partial structure represented by the following formula can be used.

R, R4 (wherein R1 represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, R2 represents an alkylene group or a phenylene group, and Rs and Ft4 represent hydrogen.

(represents an alkyl group or an aryl group, and R% represents a nitrogen-containing heterocyclic group) The above alkyl group, aryl group, alkylene group, or phenylene group may have an organo group having a nitrogen atom, or may be electrically charged. It may have a substituent such as a halogen within a range that does not impair its properties.

Further, the nitrogen-containing silane coupling agent used in the present invention generally has a structure represented by the following formula.

RSiY m n (R represents an alkoxy group or a halogen, Y represents an amino group or an organo group having at least one nitrogen atom, m and n are integers of 1 to 3, and m+nw
It is 4. ) The organo group having at least one nitrogen atom is an amino group having an organic group as a substituent, a nitrogen-containing heterocyclic group, or a nitrogen-containing ? 31st cycle J. Examples of the nitrogen-containing heterocyclic group include unsaturated heterocyclic groups and saturated heterocyclic groups, and known ones are applicable. Examples of the unsaturated heterocyclic group include Examples include the following.

Examples of the saturated heterocyclic group include the following.

The heterocyclic group used in the present invention is preferably a five-membered ring or a six-membered ring in consideration of stability.

Examples of such treatment agents include aminopropyltrimethoxysilane, amine, nobrobiltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyl Trimethoxysilane, motuputylaminopropyltrimethoxysilane, dibutylaminopropyldimethoxysilane.

Dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine.

There are trimethoxysilyl-γ-propylbenzylamine, etc. Furthermore, as the nitrogen-containing heterocycle, those having the above-mentioned structure can be used. Examples of such compounds include trimethoxysilyl-γ-propylpiperidine, trimethoxysilyl -γ-propylmorpholine, trimethoxysilyl-γ
- Propylimidazole, etc.

The applied amount of these treated silica fine powders exhibits an effect when the amount is 0.01 to 20% based on the weight of the developer, and particularly preferably when it is added in an amount of 0.03 to 5%, excellent stability is achieved. It exhibits positive chargeability. A preferred form of addition is that 0.01 to 3% by weight of treated silica fine powder based on the weight of the developer is attached to the surface of the toner particles.

Furthermore, the silica fine powder used in the present invention may be treated with a silane coupling agent or a treatment agent such as an organosilicon compound for the purpose of hydrophobization, if necessary, and a known method may be used. , treated with the above-mentioned treatment agent that reacts with or physically adsorbs the silica fine powder. Examples of such treatment agents include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, benzyldimethylchlorosilane, Bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxy Silane, diphenyljethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane,
1.3-divinyltetramethyldisiloxane, and 1
There are dimethylpolysiloxanes having 2 to 12 siloxane units per molecule and each terminal unit containing a hydroxyl group bonded to one St. These are 1
It is used as a species or a mixture of two or more species.

Finally, the degree of hydrophobicity of the treated silica fine powder was determined to be 30 as measured by methanol titration test.
When hydrophobized to show a value in the range of ~80, the triboelectric charge of the developer containing such fine silica powder becomes sharp and uniformly positive, which is preferable.Here, methanol is used. The titration test confirms the degree of hydrophobization of the silica fine powder having a hydrophobized surface.

The "methanol titration test" specified herein for evaluating the degree of hydrophobicity of the treated silica fine powder is carried out as follows.
Add to 50 mf of water in a ft Erlenmeyer flask. Methanol is titrated from the burette until all of the silica is wetted.

At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed when the entire amount of fine silica powder is suspended in the liquid, and the degree of hydrophobization is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached.

A developer for developing electrostatic images obtained by adding positively chargeable silica fine powder to a toner having a unit structure represented by formula (I) has particularly excellent properties that maintain image density even when used continuously for a long period of time. No deterioration is observed and the initial high quality image can be maintained. This is presumed to be due to the fact that the amount of triboelectric charge is constant and its distribution is sharp in a developer that combines a toner containing the unit structure represented by formula (I) and positively chargeable silica fine powder. .

That is, in a toner that combines a developing fine powder containing a compound having the formula (1) as a unit structure and a positively charging fine silica powder, the amount of triboelectric charge can be controlled with higher performance than conventional toners.

As a result, it is possible to provide a high-density image that is more durable than conventional toners and has less fog and reverse fog. Also, high temperature (32.5℃).

90%), exhibits excellent triboelectric charging ability even under low temperature and low humidity (15° C., 10%) environments, and can provide high quality images.

In order to control the amount of triboelectric charge uniformly to each individual toner particle with a sufficient amount of triboelectricity, and to control the amount of triboelectricity with high performance without deterioration due to durability or continuous use over a long period of time, the charge control agent of the present invention is required. The combination of silica powder and positively chargeable silica fine powder is extremely effective.

Colorants used in the present invention include carbon black, lamp black, iron black, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow 010-Damine 6G, lake, calco oil blue, chrome yellow, quinacridone, benzidine. Any conventionally known dyes and pigments such as yellow, rose bengal, triallylmethane dyes, monoazo dyes, disazo dyes and pigments can be used alone or in combination.

As the binder resin used in the present invention, ordinary binder resins are used. For example, monopolymers of styrene and its substituted products such as polystyrene and polyvinyltoluene; styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers, styrene-butyl acrylate copolymers, styrene-octyl acrylate copolymers, styrene - Styrene-acrylic acid ester copolymers such as dimethylaminoethyl acrylate and styrene-2-ethylhexyl acrylate copolymer: styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene- Styrene-methacrylic acid ester copolymers represented by butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate, styrene-diethylaminoethyl methacrylate, styrene-dimethylaminopropyl methacrylate, etc.: styrene-acrylonitrile copolymer, Styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer,
Styrenic copolymers such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer: polymethyl methacrylate , polybutyl methacrylate,
Polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin,
Polyvinyl butyral, polyacrylic acid resin, rosin,
Examples include modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, paraffin wax, etc., which can be used alone or in combination. Among them, considering the development characteristics, styrene resin,
Acrylic resins and polyester resins are particularly preferred.

In particular, as binder resins suitable for pressure fixing, the following can be used alone or in combination.

Polyolefins (low molecular weight polyethylene, low molecular weight polypropylene, oxidized polyethylene, etc.), epoxy resins,
Polyester resin, styrene-butadiene copolymer (monomer ratio 5-30:95-70), olefin copolymer (ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer) , ethylene-methacrylic acid ester copolymer, ethylene-vinyl acetate copolymer, ionomer resin), polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, paraffin wax, micro crystalline wax etc.

Further, when the toner of the present invention is used as a two-component developer, it is used in combination with a carrier powder.

As the vine carrier used in the present invention, all known carriers can be used, such as iron powder.

Examples include magnetic powders such as ferrite powder and nickel powder, glass beads, and those whose surfaces have been treated with resin or the like.

Furthermore, the toner of the present invention can further contain a magnetic material and be used as a magnetic toner. In this case, the magnetic material also serves as a colorant. The magnetic materials contained in the magnetic toner of the present invention include iron oxides such as magnetite, hematite, and ferrite; metals such as iron, cobalt, and nickel; Examples include alloys of metals such as aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

These ferromagnetic materials preferably have an average particle size of about 0.1 to 2 μm, and the amount contained in the toner is about 1 µm of the resin component.
The amount is about 20 to 200 parts by weight per 00 parts by weight, particularly preferably 40 to 150 parts by weight per 100 parts by weight of the resin component.

Further, it can be used in combination with conventionally known charge control agents as long as it does not adversely affect the developer of the present invention.

Further, better results can be obtained with the developer of the present invention when additives are mixed therein as required. Examples of additives include lubricants such as Teflon and zinc stearate, abrasives such as cerium oxide and silicon carbide, fluidizers such as colloidal silica and aluminum oxide, anti-caking agents, and carbon black and oxides. Examples include conductivity imparting agents such as tin, fixing aids such as low molecular weight polyethylene, and anti-offset agents. Also,
A small amount of white fine particles of opposite polarity can also be used as a developability improver.

To prepare the toner for developing an electrostatic image according to the present invention, the charge control agent according to the present invention is added to a vinyl or non-vinyl thermoplastic resin, a pigment or dye as a coloring agent, and a magnetic material as necessary. The pigments are mixed thoroughly using a ball mill or other mixer, and then melted, kneaded, and kneaded using a heat kneader such as a heated roll, kneader, or extruder to make the resins compatible with each other. Or disperse or dissolve the dye, cool and solidify, then crush and classify to obtain an average particle size of 5 to 2.
0μ toner can be obtained.

Alternatively, the material can be obtained by dispersing the material in a binder resin solution and then spray-drying it, or by mixing the specified material with the monomers that should constitute the binder resin to form an emulsified suspension and then polymerizing it. A polymerization method for obtaining a toner or a method for forming a capsule toner consisting of a core and a shell can be applied.

The present invention will be specifically explained below with reference to Examples, but this is not intended to limit the present invention in any way. All parts in the following formulations are by weight.

Example 1 The above materials were thoroughly mixed in a blender and then kneaded with two rolls heated to 150°C. After the kneaded material was left to cool naturally, it was roughly pulverized with a cutter mill, then pulverized with a pulverizer using a jet stream, and further classified using a power classifier to obtain a black fine powder with a number average particle size of 10μ. (used as toner) was obtained.

On the other hand, a fine silica powder synthesized by a dry method has the trade name Aerosil #200. A positively charged silica fine powder with a hydrophobicity degree of 60 was obtained by treating a silicone oil with a specific surface area of approximately 200 m'/g (manufactured by Aerosil) with a silicone oil containing a primary amine in its side chain (nitrogen atom equivalent: 830.60°C, viscosity at 80 cps). Obtained.

The silicone oil contains the structure of the following formula as a partial structural unit.

CH.

-0-3i- (CH2)! H2 0.4 parts by weight of the obtained treated silica fine powder was added to 100 parts by weight of the black fine powder! It was added to a certain amount to prepare a developer.

Images of this developer were obtained using an electrophotographic printer using an amorphous silicon photoreceptor and evaluated.

Incidentally, when measured by the blow-off method, the tribo value of the developer was +11.0 μC.

FIG. 5 shows an embodiment of an electrophotographic printer to which the developer of the present invention can be applied. An electrical signal input to a laser modulation unit 1 is output as a modulated laser beam, and is outputted as a modulated laser beam. - The longitudinal direction of the photosensitive drum 4 is scanned by the θ lens 3. The photosensitive drum 4 rotates in the direction of the arrow, making it possible to scan the laser beam two-dimensionally.

As a photoreceptor, amorphous silicon, selenium, CdS
, an organic photoreceptor, etc. are used, and are sensitized to have sensitivity to the wavelength (780 nm to 800 nm) of a semiconductor laser, for example. In this embodiment, an amorphous silicon photoreceptor is used as such a photoreceptor, and after leveling the potential on the surface of the photoreceptor with an AC static eliminator 5, it is charged to 380V with a charger 6. Thereafter, laser beam exposure is performed to form a dot latent image on the photoreceptor by an image scanning method using a ternary dither method. The three M levels are formed by pulse width modulation of laser light as shown in FIG. 3(a). ′
The m image potential was 250V at H level and 120V at M level.

Such a dot latent image was reversely developed by a one-component insulating magnetic toner developer 9 (or 11) containing a developer containing the above-mentioned toner. At this time, a developing bias of 280 V was applied as a DC component.

The thus developed image was then transferred onto the transfer paper 12 by the transfer charger 11 and fixed onto the transfer paper 12 by the fixing device 13. Further, toner remaining on the photosensitive drum 4 without being transferred is collected by a cleaner 14. The image thus formed on the transfer paper has an H level of 1.471
The M level was 0.62, and the image density in the solid area was sufficiently high, the dots were sharp, and the photographic image, which serves as a guide for halftone reproduction, was also clearly reproduced. Also, after repeating 100,000 copies, the H level fluctuation was ±0.
0.7 or less, M level fluctuation is within ±0.15, and V
No major change was required in the s-Dp characteristics. Furthermore, when the environmental conditions were set to 35°C, 85%, and 15°C, 10%, good images were obtained in both cases, similar to those at room temperature, and no major changes were observed in these images even after repeated use of 100,000 sheets. .

Furthermore, this developer was stored for half a year, but there were no major changes in its initial characteristics.

Furthermore, fogging and reverse fogging were not a problem throughout the durability test.

Examples 2 to 6 Images were produced in the same manner as in Example 1, except that the charge control agent and treated silica fine powder shown in Table 1 were used instead of the compound example (1) and positively charged silica fine powder used in Example 1. I got it and evaluated it. The results are shown in Table 2.

Chapter 1 Table @1 Silicone oil A: The following parts are nitrogen-containing organo groups: Has a structure.

night @2 Silane coupling agent A: Silane coupling having the following structure 3% by weight of gluing agent and dimethyldichlorosilica A total of 2% by weight was used.

CH30Ca H2 O2 silicone oil B: The following parts are nitrogen-containing organo groups: Has a structure.

CH.

■4 Silane coupling agent B: Silane coupling having the following structure 3% by weight of gluing agent and dimethyldichlorosilica A total of 2% by weight was used.

Hs　O H30 ■5 Silicone oil C: The following parts are nitrogen-containing origano groups: Has a structure.

Table 2 In addition, durability tests were conducted on these developers, and the maximum variation in H level was within ±0.1, and variation in M level was also within ±0.12, so no practical problems were observed. . Also, through durability, clear images were obtained without any problems with fog or reverse fog.

Furthermore, the environmental conditions were 35°C, 85% and 15°C.

When the ratio was set to 10%, good images were obtained in both cases at room temperature.

Example The procedure of Example 1 was repeated except that styrene-butyl methacrylate-dimethylaminoethyl methacrylate (weight ratio 7:2.5:0.5) was used instead of fustyrene-butyl acrylate. The obtained image has an H level of 1.4
5. The M level was 0.65, and the image density in the solid area was sufficiently high, the dots were sharp, and the photographic image, which serves as a guide for halftone reproduction, was also reproduced clearly.

In addition, although 100,000 copies were repeatedly made, the variation in H level was within ±0.07, the variation in M level was within ±0.15, and no change was observed in the Vs-Dp characteristics in practical terms. . Furthermore, the environmental conditions were changed to 35℃, 85% and 15℃, 10%.
%, good images were obtained in both cases at room temperature and at room temperature, and no change was observed in practical use even after repeated use of 100,000 sheets. Further, no increase in reverse fog was observed throughout the durability test.

Example 8 The same procedure as in Example 1 was carried out except that 50 parts of γ iron oxide was used instead of 60 parts of magnetite.

The resulting sepia image showed 1.36 at the H level and 0.59 at the M level, and the image density in the solid area was sufficiently high and the dots were sharp, making it a photographic image that can be used as a guide for halftone reproduction. was also beautifully reproduced. I made 100,000 copies repeatedly, but the H level fluctuation was within ±O0O.
The level fluctuation was within ±0.15, and no practical change was observed in the V8-Dp characteristics. Furthermore, m platform 4-#
When - was changed to 35° C. and 85% to 15j-10%, good sepia images were obtained in both cases, similar to those at room temperature, and no change was observed in practical use even after repeated use of 100,000 sheets.

Further, no increase in reverse fog was observed throughout the durability test.

Example 9 The above materials were thoroughly mixed in a blender and then kneaded with two rolls heated to 150°C. After allowing the kneaded mixture to cool naturally, it is coarsely pulverized using a cutter mill, then pulverized using a pulverizer using a jet stream, and further classified using an air classifier to obtain a fine powder with a particle size of 5 to 20μ (toner). ) was obtained. To this fine powder, 0% of the positively chargeable silica fine powder used in Example 1 was added.
．． 4 wt% was added externally.

A developer was prepared by mixing 5 parts of the externally added fine powder with 100 parts of iron powder carrier having an average particle size of 50 to 80 microns.

Next, by a conventionally known electrophotographic method,
A negative electrostatic image was formed, and this was powder-developed using the above-mentioned developer using a magnetic brush method to create a toner image, which was transferred to plain paper and heat-fixed.

The resulting transferred image had a sufficiently high density of 1.41, had no fogging, and had no toner scattering around the image, resulting in a good image with high resolution.

Further, during durability, the above-mentioned filming phenomenon related to toner on the photoreceptor was not observed at all, and no problems were found in the cleaning process. Also, ``At this time, there was no trouble in the fixing process, too, oo.

At the end of the sheet durability test, the fuser was observed, and there were no scratches or damage to the rollers, and there was almost no staining due to offset toner, so there were no practical problems at all.

Furthermore, when the environmental conditions were set to 35°C and 85%, the image density was 1.32, a value that was almost unchanged from normal temperature, and a clear image was obtained without fogging or scattering.

Next, when a transferred image was obtained at 15° C. and 10% low temperature and low humidity, the image density was as high as 1.44, solid black was developed and transferred extremely smoothly, and the image was excellent with no scattering or hollow spots.

Examples 10 to 14 Images were obtained and evaluated in the same manner as in Example 9, except that the charge control agent and treated silica fine powder shown in Table 1 were used instead of the charge control agent and silica fine powder used in Example 9. did. The results are shown in Table 3.

Table 3 Image density Further environmental conditions: 35°C, 85% and 15°C.

When the ratio was set to 10%, good images were obtained in both cases at room temperature.

Further, during durability, there were no problems with fogging or reverse fogging, and no filming phenomenon was observed at all.

Comparative Example 1 Dibutyltin oxide (CCa He ) 2 was used instead of dicyclohexyltin porate used in Example 12.
A developer was obtained in the same manner as in Example 11, except that 3 parts of an O) were used. Using this toner, an image was formed and evaluated in the same manner as in Example 12. At the initial stage of development, the density is 1.
．． Although 30 images were obtained, the image density had already decreased to 0.8 after 10,000 copies were repeated.
5 The above materials were thoroughly mixed in a blender and then kneaded with two rolls heated to 150°C. The kneaded material was allowed to cool for 9 days, then coarsely pulverized with a cutter mill, pulverized with a pulverizer using a jet stream, and further classified with an air classifier to obtain black fine powder with a number average particle size of 1oμ. I got it.

0.4 parts by weight of the positively charged silica fine powder used in Example 1 was added to 100 parts by weight of the above fine powder to prepare a developer. Using this developer, an image was obtained and evaluated in the same manner as in Example 1, and as in Example 1, good results were obtained.

Example 16 The above materials were thoroughly mixed in a blender and then kneaded with two rolls heated to 150°C. The kneaded material was left to cool naturally, coarsely pulverized using a cutter mill, then pulverized using a pulverizer using a jet stream, and further classified using an air classifier to obtain a fine powder with a particle size of 5 to 20μ. .

Next, 50 parts of magnetic particles having a particle size of 50 to 80 μm were mixed with 100 parts of the fine powder to prepare a developer.

When this developer was used to develop an image using the developing method shown in Figure 1, a good image with a bright blue color was obtained. However, no change was observed in the image density.

In the present developing method shown in FIG. 6, 1 is an electrostatic image carrier;
2 is a toner carrier, 3 is a hopper, 52 is a magnetic brush with carrier toner mixture, 58 is a toner thickness regulating blade, 50 is a fixed magnet, 6 is a developing bias, 5 is a toner, that is, toner carrier 2 The magnetic brush 52 formed above is circulated by rotating the toner carrier 2, and takes in the toner in the hopper 3 and coats it in a thin layer uniformly on the toner carrier 2. Next, the toner carrier 2 and the electrostatic image are coated. The holding member 1 is opposed to the holding member 1 with a gap larger than one layer of toner, and the toner 5 on the holding member 1 is developed by flying onto the electrostatic charge image on the holding member 1.

The thickness of the toner layer is controlled by the size of the magnetic brush 52, ie, the amount of magnetic particles, and the regulating blade 58. The gap between 1 and 2 may be made larger than the thickness of the toner layer, and a developing bias of 6 may be applied.

[Brief Description of the Drawings] Figures 1 (a) and (b) are diagrams showing the concept of a multivalued dither matrix, and Figures 2 (a) and (b) and Figure 3 (a).
) and (b) are diagrams showing characteristic graphs showing the exposure intensity distribution and the potential distribution of an electrostatic latent image when performing three-value recording;
FIG. 5 is a diagram schematically showing a specific example of an electrophotographic printer to which the toner of the present invention is applied, and FIG. 6 is a diagram showing a graph showing the development characteristics of a multivalued latent image. FIG. 3 is a diagram schematically showing the electrophotographic developing section used in Example 16. 1 ------- Laser modulation unit, 2 -------
-Scanner/mirror 4-----1 photosensitive drum, 5--------AC static eliminator, 6------1 charger, 9------1 developer, 11--1- --Transfer charger.

Claims (3)

[Claims] (1) At least a binder resin colorant and the following general formula (
A developer for developing an electrostatic image, comprising a positively charged toner having a positively charged control agent having the unit structure represented by I) and positively charged silica fine powder. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (However, R^1 and R^2 are monovalent organic groups and represent the same or different groups, and M represents an element of group III in the periodic table. (X represents a monovalent group.) (2) Positively charged silica fine powder is silica fine powder with the formula R_
mSiY_n [wherein R represents an alkoxy group or halogen, m represents an integer of 1 to 3, Y represents an amino group or an organo group having at least one nitrogen atom,
n represents an integer of 1 to 3 such that m+n is 4. The developer for developing an electrostatic image according to claim 1, which is treated with a silane compound represented by the following. (3) Electrostatic image development according to claim 1, wherein the positively charged silica fine powder is obtained by treating the silica fine powder with a silicone oil having an organo or amino group having a nitrogen atom in a side chain. developer.