JP3723234B2 - Image forming toner - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an image forming toner used for electrophotography, electrostatic printing, and the like.
[0002]
[Prior art]
Conventionally, so-called two-component dry developers composed of a mixture of carrier particles and toner particles are well known. In this two-component dry developer, minute toner particles are held on the surface of relatively large particles by the electric force generated by the friction of both particles. The attracting force in the direction of the latent image with respect to the toner particles by the electric field to be formed overcomes the binding force between the toner particles and the carrier particles, and the toner particles are attracted and adhered onto the electrostatic latent image to visualize the electrostatic latent image. Is. The developer is repeatedly used while replenishing the toner consumed by the development.
[ 0003 ]
Conventionally, in such a development system, after the electrostatic latent image is transferred to transfer paper, the untransferred toner remaining on the photoreceptor is collected and discarded by a mechanism that removes the rubber-like elastic blade by contacting the photoreceptor. It was. However, a system for recycling and transporting such collected toner again to the toner bottle has been proposed and put into practical use as the recyclability has increased. However, in order to form an image of good image quality in the system, it is necessary that the toner has high fluidity. From this point, a fluidizing agent composed of silica fine particles or the like is mixed with the toner powder. Yes.
[ 0004 ]
For example, as disclosed in JP-A-51-120631, JP-A-48-47346, and JP-A-51-101535, there is a method of adding an oxide such as silicon, titanium, or aluminum to a developer composition. However, in recent years, a toner using a resin or wax having a low softening point, such as a toner used for low-temperature fixing and high-speed copying, is not sufficient in fluidity due to the adhesiveness of the resin, and fluidity is further increased. An additive that improves is desired. Furthermore, as a method for solving this problem, a method in which two types of additives having different characteristics are mixed and used has been proposed. For example, JP-A-60-136755 discloses a mixture of silica and titanium. Japanese Patent Application Laid-Open Nos. 61-188546 and 2-151872 disclose mixing additives having different particle diameters. Further, JP-A-61-249059 discloses mixing of hydrophobic silica and hydrophilic silica, and JP-A-61-20053 discloses a positive polarity additive and a negative polarity additive. A mixture of is disclosed. Although the use of these additives has led to a comparative improvement in the disadvantages of the prior art, toners applied to recycling systems using low softening point resins and waxes are related to fluidity and image smudges. It was still inadequate.
[ 0005 ]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems in the prior art, and in a low-temperature fixing recycling system, toner does not aggregate or fluidity is lowered, and there is no background contamination on the organic photoreceptor, which is good for a long time. An object of the present invention is to provide an image forming toner capable of forming a high image quality.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, after the toner image obtained by developing the electrostatic latent image on the organic optical semiconductor is transferred to the transfer paper, the untransferred toner remaining on the organic optical semiconductor is removed from the rubber elastic blade. An image forming toner for use in an image forming method in which toner collected by a toner collecting device having a mechanism of removing by contact with an optical semiconductor is circulated to a developing device and reused, and the toner has an average of 5 to 10 μm It has a particle size and a softening temperature of 85 ° C. or less, contains at least one binder resin, a colorant, and a charge control agent as main components, and further, as a fluidity improver, compared to the charge amount of the base toner. It contains two types of additives: an additive that increases the charge amount of the toner and an additive that decreases the charge amount of the toner. The release agent is a liberated fatty acid carnauba wax having an acid value of 5 or less and / or a montan ester wax. And / or an oxidized rice wax having an acid value of 10 to 30 and a cohesion degree of the toner is in the range of 5 to 15%. The toner has a charge amount of the toner with respect to the base toner. The additive to be increased is obtained by stirring and adding the additive more strongly than the additive for decreasing the charge amount of the toner .
According to a second aspect of the present invention, in the toner for image formation according to the first aspect, the toner is obtained by first adding and mixing an additive for increasing the charge amount of the toner to the base toner. The toner is obtained by mixing an additive for reducing the charge amount of the toner.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, after a toner image obtained by developing an electrostatic latent image on an organic optical semiconductor is transferred to transfer paper, untransferred toner remaining on the organic optical semiconductor is transferred to a rubber-like elastic blade on the organic optical semiconductor. A toner used in an image forming method in which toner collected by a toner collecting device having a mechanism of removing by contact is circulated to a developing device and reused, and the toner has an average particle diameter of 5 to 10 μm and 85 ° C. or less Softening temperature, containing at least one binder resin, colorant, and charge control agent as main components, and further increasing the charge amount of the toner compared to the charge amount of the base toner as a fluidity improver Two types of additives, an additive for reducing the charge amount of the toner, and a release agent fatty acid carnauba wax and / or a montan ester wax and / or an acid having an acid value of 5 or less. Together contain 10 to 30 oxidized rice wax, cohesion of the toner image forming toner according to claim is provided to be in the range of 5-15%.
[ 0007 ]
As a result of extensive research, the present inventors have first added and mixed an additive that increases the charge amount of the toner relative to the charge amount of the base toner alone. By adding an additive that decreases the charge amount, the additive that increases the charge amount is held inside the toner, and thus it has been found that good results can be obtained with no image smear. is there. In addition, an additive that increases the charge amount of the toner as compared with the charge amount of the base toner alone is more strongly stirred than an additive that decreases the charge amount of the toner and is added and mixed, so that a stable chargeability is always obtained. be able to.
[ 0008 ]
Since the toner particles collected in the recycling process are repeatedly used in the image forming process, the toner particles are frequently subjected to mechanical external force, and as a result, the additive is buried in the toner, and the cohesiveness of the toner is deteriorated. However, as in the configuration of the present invention, by using a toner in which an additive that adheres weakly on the outside of the additive that adheres firmly is used, the toner is less buried and the cohesiveness is not deteriorated. Aggregation can be prevented.
[ 0009 ]
Furthermore, in the present invention, by using an additive that increases the charge amount of the base toner by 5 to 50% as an additive that increases the toner charge amount, a good toner that does not cause image smearing can be obtained. is there. In addition, when an additive for reducing the charge amount of the toner is added, a good toner that does not cause image top stains can be obtained by using an additive that reduces the charge amount of the base toner by 5 to 50%. .
[ 0010 ]
Examples of the additive include hydrophobic silica. This is because silica has a particularly excellent effect of improving fluidity compared to other additives. The amount of these additives added is 0.1 to 5.0 parts by weight, preferably 0.2 to 2.0 parts by weight, based on the base toner when two types are mixed. When the amount is less than this range, a sufficient charge amount and fluidity cannot be imparted to the toner. Conversely, when the amount is more than this range, the environmental dependency of the charge amount and fluidity increases. As a method for producing the base toner, a conventionally known method may be used. For example, a binder resin, a colorant, a wax, and a charge control agent are melted and kneaded with a hot roll, and then cooled and solidified, and then pulverized with a pulverizer such as a jet mill. It is obtained by classifying. As the binder resin used in the base toner of the present invention, it is necessary to use 50% by weight or more of a polyester resin for low-temperature fixing. Examples of the resin used in combination include polystyrene, chloropolystyrene, and poly-α. -Still styrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer styrene resin, vinyl chloride resin, styrene -Vinyl acetate copolymer, rosin-modified maleic resin, pheny Examples of the resin include epoxy resin, epoxy resin, low molecular weight polyethylene, low molecular weight polypropylene, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, and polyvinyl butyral resin.
[ 0011 ]
As the mold release agent used in the present invention, solid silicone varnish, higher fatty acid higher alcohol, montan ester wax, oxidized rice wax, low molecular weight polypropylene wax, carnauba wax and the like can be used. The effect is remarkable when carnauba wax is used. De-free fatty acid type carnauba wax is a carnauba wax made from carnauba wax, and free fatty acids are eliminated. Therefore, the acid value is 5 or less, and it becomes finer than conventional carnauba wax, and it is contained in the binder resin. The dispersion diameter becomes 1 μm or less and the dispersibility is improved, so that the effect as a wax is increased and aggregation in the recycling process is reduced.
[ 0012 ]
Carnauba wax usually has a relatively low melting point of 80 to 86 ° C., so it is very useful for low-temperature fixing toner. In the present invention, the amount of wax used is 1 to 15% by weight, preferably 2 to 10% by weight, based on the binder resin.
[ 0013 ]
The oxidized rice wax of the present invention is obtained by air-oxidizing rice bran wax. The acid value is preferably 10 to 30, and if it is less than 10, the lower limit fixing temperature increases and the low temperature fixability becomes insufficient. If it exceeds 30, the cold offset temperature increases and the low temperature fixability becomes insufficient. Further, the above wax may be used alone or in combination, and the good results shown above can be obtained by containing 1 to 15 parts by weight of the whole toner. As the mold release agent used in the present invention, the waxes are most preferable, but known mold release agents other than the wax may be used.
[ 0014 ]
As the colorant used in the present invention, carbon black, lamp black, aniline blue, phthalocyanine blue, phthalocyanine green, chrome yellow, quinacridone, rose bengal, triallylmethane dyes, and the like can be used alone or in combination. Can be used. The amount of these colorants to be used is usually 1 to 30 wt%, preferably 3 to 20 wt% with respect to the binder resin. In the present invention, the additive may be mixed with the base toner by a conventionally known method, and can be mixed by an apparatus such as a Henschel mixer or a speed kneader.
[ 0015 ]
Specific examples of the recycling system are shown in FIG. 1 and FIG. The toner on the photosensitive drum 14 after the transfer process is scraped off by the cleaning brush 5 and the cleaning blade 4. The cleaning blade 4 is supported at one central point so that the left and right pressures are uniform, and is constantly pressurized by a spring 7. The cleaning brush 5 rotates in the opposite direction to the photosensitive drum 14 and removes foreign matters such as a piece of paper that is difficult to remove with the cleaning blade 4. The toner scraped off by the cleaning brush 5 and the cleaning blade 4 is collected by the toner collecting roller 6 in the toner collecting unit 8 and then conveyed again to the toner hopper 10 by the coil type toner conveying unit 9.
[ 0016 ]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[ 0017 ]
Example 1
Polyester resin 65 parts of styrene - 1 parts of butyl acrylate 35 parts carnauba wax 4 parts of carbon black 4 parts quaternary ammonium salt [0018]
The mixture having the above composition is sufficiently mixed and stirred in a Henschel mixer , heated and melted at a temperature of 130 ° C. to 140 ° C. for about 30 minutes with a roll mill, cooled to room temperature, pulverized and classified, and the volume average particle size is obtained. An 8.5 μm base toner was obtained. When the charge amount of the obtained toner was measured by the blow-off method, it was 20 μc / g. To 1.0 kg of the above base toner, 2.0 g of titanium oxide fine powder as additive 1 (charge amount when added to base toner is 7 μc / g) and silicon oxide fine powder as additive 2 (added to base toner) Then, 2.0 g of the charged amount was 35 μc / g) and mixed at 1000 rpm with a Henschel mixer at the same time to obtain a toner. When the charge amount of the obtained toner was measured, it was 24 μc / g. Further, the aggregation degree of the toner was measured with a powder tester manufactured by Hosokawa Micron and found to be 12%.
[ 0019 ]
Using the toner and carrier obtained as described above, a developer is prepared, put into a remodeling machine equipped with a recycling function in the electrophotographic copying machine FT4820 (manufactured by Ricoh), and a running test of 100,000 sheets is performed. The machine was turned off immediately before the transfer at 100,000 sheets, the background toner before transfer was transferred with a transparent tape, and measured with a Macbeth densitometer, it was 0.40. Further, the degree of aggregation of the recycled toner was examined and found to be 35%.
[ 0020 ]
Comparative Example 1
3. Silicon oxide fine powder (charge amount when added to base toner is 30 μc / g) as an additive to 1.0 kg of base toner (base charge amount is 20 μc / g) obtained by the method of Example 1. 0 kg was mixed with a Henschel mixer at 1000 rpm to obtain a toner.
The charge amount of the toner was measured and found to be 30 μc / g. Further, the degree of aggregation at that time was measured and found to be 25%.
Using the toner and carrier obtained as described above, a developer is prepared and put into a remodeled machine equipped with a recycling function in the electrophotographic copying machine FT4820 (manufactured by Ricoh), and 100,000 running tests are performed. The machine was turned off immediately before the transfer at 100,000 sheets, the background toner before transfer was transferred with a transparent tape, and the Macbeth ID measurement was 0.65. Further, when the degree of aggregation of the recycled toner was examined, it was poor at 65%.
[ 0021 ]
Example 2
1. Silicon oxide fine powder (charge amount when added to base toner is 5 μc / g) as an additive to 1.0 kg of base toner (base charge amount is 20 μc / g) obtained by the method of Example 1. 0 g and 2.0 g of silicon oxide fine powder (charge amount when added to the base toner is 35 μc / g) as an additive were simultaneously mixed with a Henschel mixer at 1000 rpm to obtain a toner. The charge amount of the obtained toner was measured and found to be 21 μc / g. Further, the degree of aggregation of the toner was measured and found to be 30%.
[ 0022 ]
Using the toner and carrier obtained as described above, a developer is prepared and put into a remodeled machine equipped with a recycling function in the electrophotographic copying machine FT4820 (manufactured by Ricoh), and 100,000 running tests are performed. The machine was turned off immediately before the transfer at 100,000 sheets, the background toner before transfer was transferred with a transparent tape, and the Macbeth ID measurement was 0.38. Further, the degree of aggregation of the recycled toner was examined and found to be 30%.
[ 0023 ]
Example 3
Silicon oxide fine powder (charge amount when added to base toner is 35 μc / g) as an additive to the base toner (base charge amount 20 μc / g) 1.0 kg obtained by the method of Example 1 2 0.0 g is first added and mixed at 1000 rpm in a Henschel mixer, and then 2.0 g of silicon oxide fine powder (charge amount when added to the base toner is 5 μc / g) as an additive is 1000 rpm at a Henschel mixer. Was added to obtain a toner. The toner charge amount at this time was measured and found to be 20 μc / g. Further, the degree of aggregation of the toner was measured and found to be 9%.
Using the toner and carrier obtained as described above, a developer is prepared and put into a remodeled machine equipped with a recycling function in the electrophotographic copying machine FT4820 (manufactured by Ricoh), and 100,000 running tests are performed. The machine was turned off immediately before the transfer at 100,000 sheets, the background toner before transfer was transferred with a transparent tape, and the Macbeth ID measurement was 0.32. Further, the degree of aggregation of the recycled toner was examined and found to be 22%.
[ 0024 ]
Example 4
Silicon oxide fine powder (charge amount when added to base toner is 35 μc / g) as an additive to the base toner (base charge amount 20 μc / g) 1.0 kg obtained by the method of Example 1 2 0.0 g is first added and mixed at 1500 rpm with strong stirring in a Henschel mixer, and then 2.0 g of silicon oxide fine powder (charge amount of 5 μc / g when added to the base toner) is added as an additive to the Henschel mixer. The toner was obtained by adding at 1000 rpm. The toner charge amount at this time was measured and found to be 21 μc / g. Further, the degree of aggregation of the toner was measured and found to be 7%.
Using the toner and carrier obtained as described above, a developer is prepared and put into a remodeled machine equipped with a recycling function in the electrophotographic copying machine FT4820 (manufactured by Ricoh), and 100,000 running tests are performed. The machine was turned off immediately before the transfer at 100,000 sheets, the background toner before transfer was transferred with a transparent tape, and the Macbeth ID measurement was 0.30. Further, the degree of aggregation of the recycled toner was examined and found to be 18%.
[ 0025 ]
Example 5
Silicon oxide fine powder (charge amount when added to the base toner is 27 μc / g) as an additive to the base toner (base charge amount 20 μc / g) 1.0 kg obtained by the method of Example 1 2 0.0 g is first added and mixed at 1500 rpm with strong stirring in a Henschel mixer, and then 2.0 g of silicon oxide fine powder (charge amount of 5 μc / g when added to the base toner) is added as an additive to the Henschel mixer. The toner was obtained by adding at 1000 rpm. At this time, the charge amount of the toner was measured and found to be 18 μc / g. Further, the degree of aggregation of the toner was measured and found to be 7%.
Using the toner and carrier obtained as described above, a developer is prepared, and the electrophotographic copying machine FT4820 (manufactured by Ricoh) is put into a modified machine equipped with a recycling function, and a running test of 100,000 sheets is performed. The machine was turned off immediately before the transfer at 100,000 sheets, the background toner before the transfer was transferred with a transparent tape, and the Macbeth ID measurement was 0.25. The aggregation degree of the recycled toner was examined and found to be 15%.
[ 0026 ]
Example 6
Silicon oxide fine powder (charge amount when added to base toner is 27 μc / g) as an additive to the base toner (base charge amount 20 μc / g) 1.0 kg obtained by the method of Example 1 2 0.0 g is first added and mixed at 1500 rpm with strong stirring in a Henschel mixer, and then 2.0 g of silicon oxide fine powder (charge amount of 5 μc / g when added to the base toner) is added as an additive to the Henschel mixer. The toner was obtained by adding at 1000 rpm. The toner charge amount at this time was measured and found to be 22 μc / g. Further, the degree of aggregation of the toner was measured and found to be 5%.
Using the toner and carrier obtained as described above, a developer is prepared, and the electrophotographic copying machine FT4820 (manufactured by Ricoh) is put into a modified machine equipped with a recycling function, and a running test of 100,000 sheets is performed. The machine was turned off immediately before the transfer at 100,000 sheets, the background toner before transfer was transferred with a transparent tape, and the Macbeth ID measurement was 0.22. Further, the degree of aggregation of the recycled toner was examined and found to be 13%.
[Brief description of the drawings]
FIG. 1 is a schematic view of a toner recovery device of a copying machine equipped with a recycling function to which the toner of the present invention is applied.
FIG. 2 is a schematic view of a developing device of a copying machine equipped with a recycling function to which the toner of the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Collected toner detection 2 Filler 3 Rubber cup 4 Cleaning blade 5 Cleaning brush 6 Toner collection roller 7 Spring 8 Toner collection part 9 Coil type toner conveyance part 10 Toner hopper 11 Toner supply roller 12 Stirring roller 13 Developing roller 14 Photosensitive drum

Claims (2)

A mechanism for removing a toner image obtained by developing an electrostatic latent image on an organic optical semiconductor onto a transfer paper, and then removing untransferred toner remaining on the organic optical semiconductor by bringing a rubber-like elastic blade into contact with the organic optical semiconductor An image forming toner used in an image forming method in which toner recovered by a toner recovery device having
The toner is
Having an average particle size of 5-10 μm and a softening temperature of 85 ° C. or less,
Containing at least one binder resin, colorant, charge control agent as main components,
Furthermore, as a fluidity improver, it contains two types of additives: an additive that increases the charge amount of the toner relative to the charge amount of the base toner, and an additive that decreases the charge amount of the toner,
As a mold release agent, containing a liberated fatty acid carnauba wax having an acid value of 5 or less and / or a montan ester wax and / or an oxidized rice wax having an acid value of 10-30,
The cohesion of the toner Ri near range of 5-15%,
The toner is characterized with respect to the mother body toner, an additive for increasing the charge amount of the toner, the Rukoto obtained by adding and mixing with strong agitation than additive that reduces the charge amount of the toner An image forming toner. The toner is obtained by first adding and mixing an additive for increasing the charge amount of the toner to the base toner and then mixing an additive for decreasing the charge amount of the toner. The toner for image formation according to claim 1.

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