JPH07199538A - Image forming toner - Google Patents

Abstract

PURPOSE:To provide an image forming toner capable of forming images with image quality good over a long period of time without flocculation of the toner or degradation in the flow property thereof even in a recycling system of low- temp. fixing and without surface staining of an org. photoreceptor. CONSTITUTION:This toner has an average grain size of 5 to 10mum and a softening temp. of <=85 deg.C and contains at least one of a binder resin, coloring agent and charge control agent. Further, the toner contains two kinds of an additive for increasing the electrostatic charge quantity as compared with the electrostatic charge quantity of a base material toner and an additive to decrease the electrostatic charge quantity of the toner as a flow property improving agent. The toner contains de-free fatty acid carnauba wax and/or montan- based ester wax and/or oxidized rice wax of acid value 10 to 30 as a release agent. The degree of flocculation of the toner is in a range of 5 to 15%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming toner used in electrophotography, electrostatic printing and the like.

[0002]

2. Description of the Related Art So-called two-component dry developers composed of a mixture of carrier particles and toner particles have been well known. In this two-component dry developer, minute toner particles are held on the surface of a relatively large particle by the electric force generated by the friction between the particles, and when the electrostatic latent image is approached, the electrostatic latent image is formed. The attraction force in the latent image direction with respect to the toner particles due to the electric field formed overcomes the binding force between the toner particles and the carrier particles, and the toner particles are attracted and attached onto the electrostatic latent image to visualize the electrostatic latent image. It is a thing. Then, the developer is repeatedly used while replenishing the toner consumed by the development.

Conventionally, in such a developing system, the untransferred toner remaining on the photoconductor after the electrostatic latent image is transferred onto the transfer paper is collected by a mechanism for removing a rubber-like elastic blade by contacting the photoconductor. It was abandoned. However, as the motivation for recycling has increased, a system for circulating and recycling the collected toner again to the toner bottle has been proposed and put into practical use. However, in order to form an image of good quality in the system, the toner needs to have high fluidity, and from this point, a fluidizing agent composed of silica fine particles or the like is mixed with the toner powder. There is.

For example, JP-A-51-120631 and JP-A-5-120631
As disclosed in JP-A-8-47346 and JP-A-51-101535, there is a method of adding an oxide such as silicon, titanium, or aluminum to a developer composition. In the case of a toner that uses a resin or wax having a low softening point like the toner used, the fluidity is not sufficient due to the adhesiveness of the resin, and an additive that further improves the fluidity is desired. Further, as a method for solving this, a method of mixing and using two kinds of additives having different characteristics has been proposed. For example, JP-A-60-136755 discloses a mixture of silica and titanium. Japanese Patent Laid-Open No. 61-1885
46, JP-A-2-151872 discloses that additives having different particle sizes are mixed. . further,
JP-A-61-249059 discloses mixing of hydrophobic silica and hydrophilic silica, and JP-A-61-2005.
Japanese Patent Publication No. 3 discloses a mixture of an additive having a positive polarity and an additive having a negative polarity. Although the use of these additives has made the drawbacks of the prior art relatively ameliorated, the toner applied to the recycling system using a low softening point resin or wax is associated with fluidity and background stains. , Was still inadequate.

[00]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art. Therefore, even in a low-temperature fixing recycling system, toner does not agglomerate and the fluidity does not decrease, and the organic photoreceptor is used. It is an object of the present invention to provide an image forming toner which can form a good image quality for a long time without the above background stain.

[00]

According to the present invention, after transfer of a toner image obtained by developing an electrostatic latent image on an organic optical semiconductor to a transfer paper, untransferred toner remaining on the organic optical semiconductor is removed by a rubber. A toner used in an image forming method in which the toner collected by a toner collecting device having a mechanism for removing a blade-shaped elastic blade by contacting the organic optical semiconductor is circulated to a developing device and reused. It has an average particle size of 10 μm and a softening temperature of 85 ° C. or lower, contains at least one binder resin, a colorant, and a charge control agent as main components, and further functions as a fluidity improver for the charge amount of the base toner. The release agent contains carnauba wax having an acid value of 5 or less and / or an additive for increasing the charge amount of the toner and an additive for decreasing the charge amount of the toner.
Or montan ester wax and / or acid value 1
An image forming toner is provided which contains 0 to 30 oxidized rice wax and has a degree of aggregation of 5 to 15%.

As a result of intensive studies, the inventors of the present invention first added and mixed an additive for increasing the charge amount of the toner to the image forming toner, as compared with the charge amount of the base toner alone. It has been found that by mixing the additive that reduces the charge amount of the toner, the additive that reduces the charge amount is retained inside the toner, so that it is possible to obtain good results without image background stain. It is a thing. Further, an additive that increases the charge amount of the toner as compared to the charge amount of the base toner alone is stirred and mixed more strongly than an additive that decreases the charge amount of the toner, and thus stable chargeability is always obtained. be able to.

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. But,
As in the constitution of the present invention, by using the toner in which the weakly adhering additive is present outside the strongly adhering additive,
The embedding property in the toner is reduced, and the aggregating property of the toner can be prevented without deteriorating the aggregating property.

Further, in the present invention, the charge amount of the base toner is 5 to 50 as an additive for increasing the charge amount of the toner.
By using an additive that increases the amount by%, a good toner that does not cause background smear on an image can be obtained. When an additive that reduces the charge amount of the toner is added, by using an additive that reduces the charge amount of the base toner by 5 to 50%, similarly, a good toner that does not cause background smear on the image can be obtained. .

Examples of the additive include hydrophobic silica. This is because silica has a particularly excellent fluidity improving effect as compared with other additives. Further, the addition amount of these additives is 0.1 to the base toner when two kinds are mixed.
The amount is 5.0 parts by weight, preferably 0.2 to 2.0 parts by weight. If it is less than this range, it is not possible to impart a sufficient charge amount and fluidity to the toner. On the contrary, if it is more than this range, the charge amount and fluidity are highly dependent on the environment. 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 melt-kneaded on a hot roll, cooled and solidified, and then pulverized by a pulverizer such as a jet mill. It is obtained by classification. As the binder resin used in the base toner of the present invention, it is necessary to use a polyester resin in an amount of 50% by weight or more for low-temperature fixing. Examples of the resin used in combination include polystyrene,
Chloropolystyrene, poly-α-stillstyrene, 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-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer Resin, vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenyl resin, epoxy resin, low molecular weight polyethylene,
There are low molecular weight polypropylene, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin and the like.

Further, as the 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, etc. can be used, but the effect becomes remarkable when the released fatty acid type carnauba wax is used. . The free fatty acid-type carnauba wax is a product in which free fatty acids are desorbed from carnauba wax as a raw material. Therefore, the acid value becomes 5 or less, and it becomes finer crystals than the conventional carnauba wax and becomes Since the dispersion diameter is 1 μm or less and the dispersibility is improved, the effect as a wax is increased and the aggregation in the recycling process is reduced.

Carnauba wax usually has a melting point of 80.
Since it is as low as ˜86 ° C., it is extremely 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.

The oxidized rice wax of the present invention is obtained by air-oxidizing rice bran wax. Acid value is 10
When it is less than 10, the lower limit fixing temperature rises and the low temperature fixability becomes insufficient, and when it is more than 30, the cold offset temperature rises and the low temperature fixability also becomes insufficient. The above waxes may be used alone or in combination, and if the wax is contained in an amount of 1 to 15 parts by weight based on the total amount of the toner, the above-described good results can be obtained. As the release agent used in the present invention, the above waxes are most preferable, but a known release agent other than the above wax may be used.

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 may be used alone. Alternatively, they may be mixed and used. The amount of these colorants used is usually 1 to 30 wt% and preferably 3 to 20 wt% with respect to the binder resin.
In the present invention, a conventionally known method may be used as a method of mixing the additive with the base toner, and the mixing may be performed with an apparatus such as a Henschel mixer or a speed kneader.

A concrete example of the recycling system is shown in FIGS. 1 and 2. The toner on the photosensitive drum 14 after the transfer process is scraped off by the cleaning brush 5 and the cleaning blade 4. Cleaning blade 4
Is supported at one point in the center so that the left and right pressures are uniform and is constantly pressed by the spring 7. The cleaning brush 5 rotates in the opposite direction to the photoconductor drum 14 to remove foreign matter 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 section 8 and then conveyed to the toner hopper 10 again by the coil type toner conveying section 9.

[00]

EXAMPLES The present invention will now be described in more detail with reference to Examples.

Example 1 Polyester resin 65 parts Styrene-butyl acrylate 35 parts Carnauba wax 4 parts Carbon black 4 parts Quaternary ammonium salt 1 part

After thoroughly mixing and stirring the mixture having the above composition in a Henshall mixer, the mixture is rolled at 130 ° C. to 140 ° C.
After heating and melting at a temperature of 30 ° C. for about 30 minutes and cooling to room temperature, the obtained mixture was pulverized and classified to obtain a base toner having a volume average particle diameter of 8.5 μm. The charge amount of the obtained toner was measured by the blow-off method and found to be 20 μc / g. Titanium oxide fine powder as additive 1 was added to 1.0 Kg of the base toner (charge amount when added to the base toner was 7 μc /
g) and 2.0 g of silicon oxide fine powder (charge amount when added to the base toner is 35 μc / g) as additive 2 were simultaneously mixed at 1000 rpm with a Henschel mixer to obtain a toner. The charge amount of the obtained toner was measured and found to be 24 μc / g. Further, the cohesion degree of the toner was measured with a powder tester manufactured by Hosokawa Micron and found to be 12%.

A developer is prepared by using the toner and carrier obtained as described above, and an electrophotographic copying machine FT4820 is prepared.
Put it in a modified machine equipped with a recycling function (made by Ricoh), run a running test of 100,000 sheets, turn off the machine immediately before transfer at 100,000 sheets, transfer the background toner before transfer with a transparent tape, It was 0.40 when measured with a Macbeth densitometer. Further, when the cohesion degree of the recycled toner was examined, it was 35%.

Comparative Example 1 1.0 Kg of the base toner obtained by the method of Example 1 (the charge amount of the base is 20 μc / g) is added to silicon oxide fine powder as an additive (the charge amount when added to the base toner is 30 μc /
g) 1000 kg of 4.0 kg with a Henschel mixer
m to obtain a toner. The charge amount of the toner was measured and found to be 30 μc / g. The cohesion degree at that time was 25%. Using the toner and carrier obtained as described above, a developer is prepared,
The electrophotographic copying machine FT4820 (manufactured by Ricoh) was put in a modified machine equipped with a recycling function, and a running test was performed on 100,000 sheets, and the machine was turned off immediately before transfer at 100,000 sheets.
Then, the background toner before transfer was transferred with a transparent tape, and Macbeth ID measurement was performed, and it was 0.65. or,
When the aggregation degree of the recycled toner was examined, it was bad at 65%.

Example 2 1.0 Kg of the base toner obtained by the method of Example 1 (the charge amount of the base is 20 μc / g) is added to silicon oxide fine powder as an additive (the charge amount when added to the base toner is 5 μc /
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 at the same time at 1000 rpm with a Henschel mixer to obtain a toner. The charge amount of the obtained toner was measured and found to be 21 μc / g. Further, the toner cohesion was measured and found to be 30%.

Using the toner and carrier obtained as described above, a developer is prepared and electrophotographic copying machine FT482 is prepared.
0 (manufactured by Ricoh) is put in a remodeling machine equipped with a recycling function, a running test of 100,000 sheets is performed, and at the time of 100,000 sheets, the machine is turned off immediately before transfer and the background toner before transfer is transferred by a transparent tape. The Macbeth ID measurement was 0.38. Further, when the aggregation degree of the recycled toner was examined, it was 30%.

Example 3 To 1.0 Kg of the base toner obtained by the method of Example 1 (the charge amount of the base is 20 μc / g), silicon oxide fine powder (charge amount when added to the base toner as an additive) is used. Is 35 μc
/ G) 2.0 g with a Henschel mixer
pm first added and mixed, and then as an additive, silicon oxide fine powder (charge amount when added to the base toner is 5 μc /
g) 1000 g with 2.0 g in a Henschel mixer
m to give a toner. The charge amount of the toner at this time was measured and found to be 20 μc / g. Further, the toner cohesion was measured and found to be 9%. Using the toner and carrier obtained as described above, a developer is prepared and put in a remodeling machine equipped with a recycling function in the electrophotographic copying machine FT4820 (manufactured by Ricoh) to perform a running test on 100,000 sheets. At the time of 100,000 sheets, the machine is OF just before transfer
Then, the background toner before transfer was transferred with a transparent tape, and the Macbeth ID measurement was 0.32.
Moreover, when the aggregation degree of the recycled toner was examined, it was 22%.
Met.

Example 4 1.0 Kg of the base toner obtained by the method of Example 1 (the charge amount of the base is 20 μc / g) was added to silicon oxide fine powder (charge amount when added to the base toner) as an additive. Is 35 μc
/ G) 2.0g in a Henschel mixer 1500r
pm, the mixture was first added and mixed under strong stirring, and then 2.0 g of silicon oxide fine powder (charge amount when added to the base toner was 5 μc / g) was added as an additive to a Henschel mixer at 1 g.
A toner was obtained by adding at 000 rpm. The charge amount of the toner at this time was measured and found to be 21 μc / g.
The cohesion of the toner was measured and found to be 7%.
Using the toner and carrier obtained as described above, a developer is prepared and placed in a remodeling machine equipped with a recycle function in an electrophotographic copying machine FT4820 (manufactured by Ricoh Co., Ltd.) to produce a developer.
When a running test was performed on 10,000 sheets, the machine was turned off immediately before transfer at 100,000 sheets, the background toner before transfer was transferred with a transparent tape, and Macbeth ID measurement was performed.
Met. Further, when the aggregation degree of the recycled toner was examined, it was 18%.

Example 5 1.0 kg of the base toner (charge amount of the base body is 20 μc / g) obtained by the method of Example 1 is added to fine particles of silicon oxide (charge amount when added to the base toner) as an additive. Is 27 μc
/ G) 2.0g in a Henschel mixer 1500r
pm, the mixture was first added and mixed under strong stirring, and then 2.0 g of silicon oxide fine powder (charge amount when added to the base toner was 5 μc / g) was added as an additive to a Henschel mixer at 1 g.
A toner was obtained by adding at 000 rpm. The charge amount of the toner at this time was measured and found to be 18 μc / g.
The cohesion of the toner was measured and found to be 7%.
Using the toner and carrier obtained as described above, a developer is prepared and placed in a remodeling machine equipped with a recycle function in an electrophotographic copying machine FT4820 (manufactured by Ricoh Co., Ltd.) to produce a developer.
When a running test was performed on 100,000 sheets, 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 Macbeth ID measurement was performed.
Met. Further, when the cohesion degree of the recycled toner was examined, it was 15%.

Example 6 1.0 Kg of the base toner (charge amount of the base is 20 μc / g) obtained by the method of Example 1 is added to silicon oxide fine powder (charge amount when added to the base toner) as an additive. Is 27 μc
/ G) 2.0g in a Henschel mixer 1500r
pm, the mixture was first added and mixed under strong stirring, and then 2.0 g of silicon oxide fine powder (charge amount when added to the base toner was 5 μc / g) was added as an additive to a Henschel mixer at 1 g.
A toner was obtained by adding at 000 rpm. The amount of charge on the toner at this time was measured and found to be 22 μc / g.
The cohesion of the toner was measured and found to be 5%.
Using the toner and carrier obtained as described above, a developer is prepared and placed in a remodeling machine equipped with a recycle function in an electrophotographic copying machine FT4820 (manufactured by Ricoh Co., Ltd.) to produce a developer.
When the running test was performed on 100,000 sheets, 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 performed.
Met. Further, when the aggregation degree of the recycled toner was examined, it was 13%.

[Brief description of 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]

 1 Collected Toner Detection 2 Filler 3 Rubber Cup 4 Cleaning Blade 5 Cleaning Brush 6 Toner Rotating Roller 7 Spring 8 Toner Collecting Section 9 Coil Type Toner Conveying Section 10 Toner Hopper 11 Toner Replenishing Roller 12 Agitating Roller 13 Developing Roller 14 Photosensitive Drum

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Claims (1)

[Claims] 1. A toner image obtained by developing an electrostatic latent image on an organic photosemiconductor is transferred onto a transfer paper, and untransferred toner remaining on the organic photosemiconductor is applied to the organic photosemiconductor with a rubber elastic blade. A toner used in an image forming method in which toner collected by a toner collecting device having a mechanism for removing by contact is circulated to a developing device and reused, wherein the toner has an average particle size of 5 to 10 μm and a temperature of 85 ° C. or less. It has a softening temperature, contains at least one binder resin, a colorant, a charge control agent as a main component, and further as a fluidity improver,
A release-free fatty acid carnauba wax containing an acid value of 5 or less as a release agent, containing two kinds of additives, an additive for increasing the charge amount of toner and an additive for decreasing the charge amount of toner as compared with the charge amount of base toner. And / or a montan ester wax and / or an oxidized rice wax having an acid value of 10 to 30, and the toner has an aggregation degree of 5 to 15%.