JP3034394B2 - Non-magnetic one-component development method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type non-magnetic one-component developing method for developing an electrostatic latent image using a non-magnetic toner.

[0002]

2. Description of the Related Art In general, in electrophotography, an electric latent image is formed on a photoreceptor, the latent image is developed with toner, and a toner image is transferred to a transfer material such as paper as necessary. The image is fixed by means such as heat, pressure and the like to obtain a copy. As a developer used in such an electrophotographic method, there are a two-component developer including a toner and a carrier, and a one-component developer having both functions of a toner and a carrier. One-component developers are further classified into magnetic one-component developers and non-magnetic one-component developers. The two-component developer has excellent electrophotographic properties such as transferability, fixability, and environmental resistance, but requires a toner concentration sensor to control the mixing ratio of toner and carrier, and has a short developer life. And a problem that the stirring mechanism of the developer becomes complicated. On the other hand, the magnetic one-component developer does not require the above-mentioned toner concentration sensor, and can easily reduce the size of the developing device, but has a problem that the fixing property is inferior because it contains magnetic particles. In view of such a background, a method using a non-magnetic toner as a one-component developer has recently been proposed and put into practical use in order to achieve both the simplification of the apparatus and the fixing characteristics. The one-component developing method using a non-magnetic toner includes a contact-type non-magnetic one-component developing method in which a developing roller carrying a non-magnetic toner is brought into contact with a photoreceptor having an electrostatic latent image to perform development. There is a non-contact type non-magnetic one-component developing method of developing a non-magnetic toner on a developing roller by flying a non-magnetic toner on a developing roller by providing a constant gap gap between the developing roller and the main drum. In the contact type non-magnetic one-component developing method, the non-magnetic toner on the developing roller and the photosensitive member having an electrostatic latent image are in contact with each other, so that the developing property is good. As well as friction with the photoreceptor drum,
Mechanical load on non-magnetic toner is large. On the other hand, in the non-contact type non-magnetic one-component developing method, the developer is frictionally charged only by the layer regulating member, so that the mechanical load on the developer is small. In general, the amount of non-magnetic one-component developer (hereinafter referred to as "developability") flying from the developing roller to the photosensitive drum is smaller than that of the mold, so that a sufficient image density cannot be obtained. .

In a non-contact non-magnetic one-component developing method,
One of the means for improving the developing property is to improve the fluidity by mixing and adhering hydrophobic silica or hydrophobic alumina as a fluidizing improver to the surface of the non-magnetic toner to improve the fluidity of the electrostatic latent image. It has been proposed to increase the supply of non-magnetic toner. And, since the conventional non-magnetic toner has been manufactured by the kneading and pulverizing method, the shape is irregular, and in order to improve the fluidity of the irregular-shaped non-magnetic toner, a large amount of That is, it was necessary to attach 1 to 3 parts by weight of the fluidization improver to 100 parts by weight of the nonmagnetic toner. However, such fluidization improvers generally have a strong positive or negative charge polarity. Therefore, when a large amount of the non-magnetic toner is mixed and adhered to the surface of the non-magnetic toner, the non-magnetic toner repels electrostatically, and it is difficult to obtain a uniform thin layer of the non-magnetic toner on the developing roller. Conversely, due to the charge between the toner particles, toner particles having the opposite charge to the normal charge are generated,
There has also been a problem that contributes to fogging in non-image areas. Further, in order to obtain a high-definition image, it is necessary to set the particle diameter of the non-magnetic toner to a small value of, for example, 10 μm or less in terms of volume average particle diameter. However, as a result, there was a problem that the developability was further deteriorated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional situation. Accordingly, an object of the present invention is to provide a non-contact non-magnetic one-component developing method in which a uniform toner thin layer is obtained on a developing roller, and a sufficient developing property is obtained even with a non-magnetic toner having a small particle diameter. Is to provide.

[0005]

Means for Solving the Problems The present inventors have solved the problem of the non-contact type non-magnetic one-component developing method and can obtain good developability even if the non-magnetic toner has a small particle diameter. As a result of intensive studies on the means for
By using a non-magnetic toner by a suspension polymerization method, a uniform thin toner layer can be obtained on the developing roller, which is the above object, and a non-magnetic one-component developer having good developability even with a small particle diameter. Have been found, and the present invention has been completed. That is, in the present invention, the non-magnetic toner is supplied to the developing roller, a thin layer of the non-magnetic toner is formed on the surface of the developing roller by the layer regulating member, and the electric charge is given. The non-magnetic toner is charged by the potential difference between the photosensitive drum and the developing roller. A non-contact type non-magnetic one-component developing method in which a magnetic toner flies and is developed in a non-contact manner on a photosensitive drum holding an electrostatic latent image, and then transferred to a transfer material, wherein the non-magnetic toner is charged It is produced by a suspension polymerization method in which a control agent is added and an organic peroxide having an alkyl group having 13 or more carbon atoms is added to a dispersion, and has a bulk specific gravity of 0.25.
And a volume average particle diameter of 3 to 9.5 μm.

Hereinafter, the present invention will be described in detail. FIG.
FIG. 1 is a schematic configuration diagram of a developing device used in a non-contact non-magnetic one-component developing method of the present invention. In the figure, 1 is a photosensitive drum,
2 is a hopper, 3 is a non-magnetic toner, 4 is a layer regulating member, 5
Is a developing roller using an aluminum sleeve carrying non-magnetic toner, 6 is a non-magnetic toner leakage prevention member, and 7 is a stirrer. In this developing device, an electrostatic latent image is formed on the photosensitive drum 1 by a known electrophotographic method. The non-magnetic toner 3 is accommodated in the hopper 2, and the non-magnetic toner 3 is carried on the developing roller 5 by the layer regulating member 4 so as to have a constant layer thickness and friction with the layer regulating member 4. Gives a charge. The developing roller 5 is provided between the photosensitive drum 1 and 120 μm to 3 μm.
It is installed with a gap of 00 μm. A DC or AC voltage bias is applied to the roller. The non-magnetic toner carried on the developing roller 5 is
, And flies to the surface of the photosensitive drum 1 due to a potential difference between the photosensitive drum 1 having the electrostatic latent image and the developing roller 5, and the electrostatic latent image is visualized in a non-contact manner.

Next, the non-magnetic toner constituting the present invention will be described in detail. The non-magnetic toner is colored particles obtained by adding a polymerization initiator to a dispersion in which a colorant is dispersed in a polymerizable monomer, and then subjecting the polymerizable monomer to suspension polymerization in an aqueous medium. Examples of the polymerizable monomer used in the present invention include the following compounds. Styrene, o-methylstyrene,
m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene,
2,4-dimethylstyrene, pn-butylstyrene,
Styrene such as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene and derivatives thereof; ethylene, propylene, butylene, isobutylene, etc. Ethylenically unsaturated monoolefins; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; organic acid vinyl esters such as vinyl acetate, vinyl propionate, and vinyl benzoate; methacrylic acid, methacrylic acid Me

Chill, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-methacrylate
Methacrylic acid such as octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like; acrylic acid, methyl acrylate, ethyl acrylate, acrylic N-butyl acid, isobutyl acrylate,
Acrylic acid such as propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate and the like; vinyl methyl ether, vinyl ethyl ether, vinyl Vinyl ethers such as isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone; N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone; Vinyl naphthalenes;
Acrylonitrile, methacrylonitrile, acrylamide and the like. These monomers are used alone or in combination of two or more. It is preferable to use styrene or a styrene derivative alone or as a mixture with other monomers in order to enhance the development characteristics and durability of the non-magnetic toner.

Examples of the colorant include black colorants such as carbon black, acetylene black, lamp black, channel black, and aniline black;
If a chromatic color, there may be mentioned Farnal Blue, Permanent Blue, Nigrosine Blue, phthalocyanine cyan pigment, rose bengal, xanthene magenta dye, quinacridone magenta pigment, monoazo red pigment, disazo yellow pigment, etc. However, the present invention is not limited to these.

The non-magnetic toner constituting the present invention is prepared by first preparing a dispersion containing a polymerizable monomer and a colorant. At this time, in order to uniformly disperse the colorant in the polymerizable monomer, the longest carbon atom chain in the dispersion has 13 or more carbon atoms.
The above organic peroxide having an alkyl group is added.
You. Examples of such an organic peroxide include the following compounds. Stearyl peroxide, palmityl peroxide, behenyl peroxide, myristyl peroxide, stearyl peroxyphenoxy acetate, myristyl peroxyphenoxy acetate, α-
Cumyl peroxystearate, α-cumyl peroxy myristate, t-butyl peroxystearate,
t-butyl peroxymyristylate, α-cumyl peroxybehenate, α-cumyl peroxycetylate,
t-butyl peroxybehenate, t-butyl peroxycetylate and the like. The amount of the organic peroxide to be used is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer.

As a method of dispersing the colorant in the polymerizable monomer, a method of heating the dispersion with stirring is used. In that case, you may use an ultrasonic dispersion machine etc. together. The heating temperature is 40-140 ° C, and the heating time is 30 minutes to several hours. Next, when a polymerization initiator is added to the dispersion and the polymerizable monomer is subjected to suspension polymerization in an aqueous medium, a non-magnetic toner is obtained. The polymerization initiator used in the present invention is preferably soluble in a polymerizable monomer. Examples of such a polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis-4-methoxy-2, 4-
Dimethyl valeronitrile, other azo or diazo polymerization initiators; benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, other peroxide polymerization initiators, and the like. In the present invention, it is preferable to use a combination of two or more of the above-mentioned polymerization initiators for the purpose of controlling the molecular weight and the molecular weight distribution or controlling the reaction time. If necessary, a water-soluble polymerization initiator such as ammonium persulfate and potassium persulfate may be used in combination. The amount of the polymerization initiator to be used is generally 0.1 to 20 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer. When the polymerization initiator is less than 0.1 part by weight, the molecular weight of the product polymer becomes so large that the molecular weight of the product polymer does not satisfy the properties as a non-magnetic toner. On the other hand, when the polymerization initiator exceeds 20 parts by weight, the polymerization product Is not preferred because the molecular weight becomes too low.

The above suspension polymerization reaction is preferably carried out in the presence of a suspension stabilizer. Generally, in suspension polymerization, a surfactant having a hydrophilic group and a hydrophobic group in a molecule is often used as a suspension stabilizer. The suspension stabilizer has a polar group such as a hydroxyl group, a carboxyl group and a salt thereof, a sulfone group and a salt thereof as a hydrophilic group, and is composed of a nonpolar group such as an aliphatic group and an aromatic group as a hydrophobic group. And has the ability to prevent and stabilize the coalescence of the monomer composition formed by the granulation process. Such suspension stabilizers include, for example, polyvinyl alcohol, casein, gelatin, methylcellulose,
Examples include cellulose derivatives such as methylhydroxypropylcellulose and ethylcellulose, starch and derivatives thereof, poly (meth) acrylic acid and salts thereof. These suspension stabilizers function to coat the surface of the droplets during the polymerization reaction and prevent coalescence and agglomeration of the droplets.

In the present invention, in order to improve blocking resistance and durability, suspension polymerization may be carried out by adding a crosslinking agent such as divinylbenzene. Furthermore, a charge control agent is added.
It is. As such a charge control agent, if it is positively chargeable, a nigrosine dye, a quaternary ammonium salt, etc.
As long as it is negatively charged, a metal complex of an organic compound having a carboxyl group, a sulfonic acid ester or a nitrogen-containing group, a metal-containing dye, and the like can be used. In the present invention, the suspension polymerization reaction
Usually, the polymerization is performed at a polymerization temperature of 50 ° C. or higher, and the temperature is set in consideration of the decomposition temperature of the polymerization initiator. If the set temperature is too high, the polymerization initiator is rapidly decomposed, which affects the molecular weight and the like, which is not preferable. In addition, neutral salts such as sodium chloride and sodium sulfate may be added to the continuous phase (aqueous phase) for the purpose of preventing emulsification. For the purpose of preventing coalescence of the monomer composition particles formed in the granulation step, a thickener such as glycerin or ethylene glycol may be added.

Non-magnetic toner constituting the [0014] present invention is used having a particle size of 3 ～9.5Myuemu volume average particle diameter
Can be If it is less than 3 μm, sufficient fluidity cannot be obtained. On the other hand, if it is larger than 9.5 μm, the reproducibility of pixels such as fine lines and characters deteriorates. The bulk specific gravity of the non-magnetic toner is
It needs to be 0.25 or more. Bulk specific gravity is 0.2
A non-magnetic toner having a particle size of less than 5 has poor fluidity required for forming a uniform thin film on the developing roller, that is, poor transportability, resulting in insufficient developability. In addition, the measurement of the bulk specific gravity is based on JIS K
This is performed according to 5101. Furthermore, a fluidizing improver such as hydrophobic silica, hydrophobic alumina or carbon black may be adhered to the surface of the non-magnetic toner using a mixing stirrer such as a Henschel mixer or a super mixer. In this case, the amount of adhesion is preferably 0.1 to 1.5 with respect to 100 parts by weight of the non-magnetic toner in order to avoid the influence of the triboelectricity of the fluidization improver itself.

[0015]

In order to obtain a uniform thin toner layer on the developing roller, it is necessary that the fluidity of the non-magnetic toner is good and that the transportability of the non-magnetic toner on the developing roller is good. In the present invention, a non-magnetic toner having good fluidity can be obtained by using a non-magnetic toner having a spherical shape by a suspension polymerization method instead of a non-magnetic toner having an irregular shape by a conventional kneading and pulverizing method. The toner transportability on the developing roller is improved, and as a result, good developability can be obtained. Since the non-magnetic toner produced by the suspension polymerization method of the present invention has essentially good fluidity due to its shape, the addition amount of the fluidization improver may be very small.
Therefore, electrostatic aggregation and repulsion between the non-magnetic toner particles due to the addition of the fluidization improver are reduced, and a uniform thin toner layer can be formed on the developing roller. Further, even when the toner particle diameter is small, the fluidity is good and good developability is obtained. Further, since the non-magnetic toner produced by the suspension polymerization method of the present invention has a spherical shape, it can be filled evenly on the developing roller, and thus a uniform thin toner layer can be formed. Further, the non-magnetic toner produced by the suspension polymerization method of the present invention has better dispersibility of the colorant and the charge control agent inside the toner particles than the toner produced by the conventional kneading and pulverizing method. For this reason, according to the present invention, it is possible to impart uniform chargeability to individual toner particles. As a result, the charging characteristics are improved, and the developability is improved.

[0016]

The present invention will be described below with reference to examples. In the examples, parts are parts by weight. Example 1 20 g of stearyl peroxide was dissolved in a mixed solution of 800 g of styrene and 200 g of n-butyl acrylate, and 120 g of carbon black (Mitsubishi Kasei Industries # 40) was further dissolved.
And 30 g of a nigrosine dye (Bontron N04 manufactured by Orient Chemical Industries) was added and stirred. With further stirring, the mixture was heated at 40 ° C. for 4 hours. 2,2′-azobisisobutyronitrile 2 is added to the obtained slurry.
5 g was mixed and dissolved. This solution was added to an aqueous solution of polyacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd., about 25%, 8000 to 12000c).
(p, 25 ° C.) A solution prepared by dissolving 80 g of sodium sulfate and 45 g of sodium sulfate in 5000 g of distilled water was added, and the mixture was stirred with a stirrer (Homomixer M type) at 10,000 rpm for 20 minutes to obtain a dispersion. This dispersion was added to a reflux tube 5
Added to a liter separable flask container. After the inside of the reaction vessel was purged with nitrogen for 30 minutes, the mixture was heated to 95 ° C. with a stirrer having a turbine type stirring blade having a diameter of 50 mm.
The mixture was stirred at 0 rpm for 9 hours. Thereafter, while maintaining the stirring, the inner solution was cooled to room temperature, the polymer particles were separated by filtration, washed well with water, and dried to obtain a spherical non-magnetic toner. When the particle size of the obtained spherical non-magnetic toner was measured using a Coulter counter (aperture: 100 μm), the volume average particle size of the non-magnetic toner was 6.2.
μm. Next, 0.5 part of hydrophobic alumina (RFY-C, manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts of the non-magnetic toner, and the mixture was stirred for 2 minutes with a Henschel mixer. A non-magnetic toner constituting the present invention was obtained by attaching hydrophobic alumina to the surface of the toner.

Example 2 Hydrophobic alumina (RFY-C, manufactured by Nippon Aerosil Co., Ltd.) was used as a fluidization improver for 100 parts of the non-magnetic toner to which the hydrophobic alumina obtained in Example 1 was not adhered to the surface.
0.3 parts and carbon black (Mitsubishi Kasei Industries # 4
0) and stirred with a Henschel mixer for 2 minutes to attach hydrophobic alumina and carbon black to the surface of the non-magnetic toner to obtain a non-magnetic toner constituting the present invention.

Example 3 The non-magnetic toner having no hydrophobic alumina adhered to the surface obtained in Example 1 was directly used as the non-magnetic toner constituting the present invention.

Comparative Example 1 Raw materials were mixed in the following composition, melt-kneaded, and then pulverized and classified to obtain a non-magnetic toner having an irregular shape and a volume average particle diameter of 6.5 μm. Next, 1.0 part of hydrophobic alumina (RFY-C manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts of the non-magnetic toner, and the mixture was stirred for 2 minutes with a Henschel mixer. A non-magnetic toner for comparison was obtained by adhering.

Comparative Example 2 1.0 part of hydrophobic alumina (RFY-C manufactured by Nippon Aerosil Co., Ltd.) and carbon black were added to 100 parts of the non-magnetic toner on which the hydrophobic alumina obtained in Comparative Example 1 was not adhered to the surface. (Mitsubishi Kasei Kogyo Co., Ltd. # 40) and stirred with a Henschel mixer for 2 minutes to attach hydrophobic alumina and carbon black to the surface of the non-magnetic toner to obtain a non-magnetic toner for comparison. . Comparative Example 3 Pulverization and classification conditions after melt kneading in Comparative Example 1
Was changed to have an irregular shape and a volume average particle diameter of 9.0 μm.
m of non-magnetic toner, and 100 weight of the non-magnetic toner
Parts, hydrophobic silica (Nippon Aerosil R-
972) Add 1.0 part and use Henschel mixer for 2 minutes
Stir for a while and attach hydrophobic silica to the surface of the non-magnetic toner.
A non-magnetic toner for comparison was obtained. Comparative Example 4 In Example 1, stearyl peroxide was not used, and
Quaternary ammonium salt (Oriet)
Using Bontron P-51)
Outside is the volume average by the suspension polymerization method as in Example 1.
A comparative non-magnetic toner having a particle diameter of 5.7 μm was obtained . Next, the bulk specific gravities of the non-magnetic toners obtained in Examples 1 to 3 and the non-magnetic toners obtained in Comparative Examples 1 to 4 were measured, and the results are as shown in Table 1. The larger the value of the bulk specific gravity is, the better the fluidity is, and it is a measure of the uniformity of forming a thin layer on the developing roller. Show.

[0021]

[Table 1]

As is clear from Table 1, the non-magnetic toner constituting the present invention has a bulk specific gravity necessary for forming a uniform thin film on a developing roller, and a small amount of a fluidization improver is sufficient. It was confirmed that it had fluidity.

Next, the non-magnetic toner obtained by the above-described operation is replaced with a commercially available magnetic one-component printer (trade name: L, manufactured by Kyocera Corporation).
-880) (developing bias DC voltage -100
V and the surface potential of the photoreceptor were modified to -900 V), and a print test was performed. As a result, in each of the non-magnetic toners of Examples 1 to 3, a uniform thin toner layer was obtained on the developing roller, and a good image having a sufficient image density was obtained. In contrast, Comparative Examples 1 to
With the non-magnetic toner of Comparative Example 4 , a uniform toner thin layer was not obtained on the developing roller, and a good image was not obtained.

[0024]

According to the present invention, by using a spherical non-magnetic toner by the suspension polymerization method as described above, it becomes possible to obtain good toner transportability on a developing roller.
As a result, a uniform thin toner layer can be obtained on the developing roller, and good developing characteristics can be obtained even when the nonmagnetic toner has a small particle diameter.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a non-contact type non-magnetic one-component developing apparatus for carrying out the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Hopper 3 Non-magnetic toner 4 Layer regulating member 5 Developing roller 6 Leak prevention member 7 Stirrer

Continuation of the front page Judge, Supreme Referee Susumu Sakai, Judge Miyako Kaneo, Judge Koji Ueno (56) References JP-A-4-9070 (JP, A) JP-A-4-190247 (JP, A) JP-A-4- 248564 (JP, A) JP-A-59-45468 (JP, A) JP-A-61-250666 (JP, A) JP-B-3-20754 (JP, B2)

Claims (1)

(57) [Claims] 1. A non-magnetic toner is supplied to a developing roller,
A thin layer of the non-magnetic toner is formed on the surface of the developing roller by the layer regulating member and charges are given to the photosensitive drum, which holds the electrostatic latent image by causing the non-magnetic toner to fly by the potential difference between the photosensitive drum and the developing roller. Develop without contact,
Next, there is provided a non-contact type non-magnetic one-component developing method for performing transfer to a transfer material, wherein the non-magnetic toner is added with a charge controlling agent.
It is, which has been produced by a suspension polymerization method in which an organic peroxide was added to the dispersion of carbon atoms having 13 or more alkyl group, and a bulk density of 0.25 or more, and a volume average A non-magnetic one-component developing method having a particle diameter of 3 to 9.5 μm.