JPH07199539A - Image forming toner - Google Patents

Abstract

(57) [Abstract] [Purpose] Image formation capable of forming good image quality for a long time without causing toner aggregation or deterioration of toner fluidity at low temperature fixing, and further without causing background stains on an organic optical semiconductor. For toner. An image forming toner used in an image forming method having an amount of film abrasion per 1000 sheets of 500 Å or less and using an organic optical semiconductor containing a polycarbonate resin as a resin binder of a charge transfer layer, comprising: The toner has an average particle size of 5 to 10 μm and a softening temperature of 85 ° C. or less, and is composed of base particles containing at least one binder resin, a colorant, and a charge control agent as main components, and the base particles flow to the base particles. As the property improving agent, two kinds of additives, that is, an additive for increasing the toner charge amount and an additive for decreasing the toner charge amount as compared with the charge amount of the mother particles alone are added, and a release agent of 5 or less is added. An image forming sheet containing a free fatty acid carnauba wax and / or a montan ester wax and / or an oxidized rice wax having an oxidation of 10 to 30. Over

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 Inorganic photoconductive materials such as selenium, cadmium and zinc oxide have been generally known as electrophotographic photoreceptors. However, these substances have problems in safety at the time of disposal or use, and are organic harmless organic semiconductors (O
PCs) are being used. This OPC
Nowadays, it is possible to obtain performance comparable to inorganic photoconductors in terms of charging characteristics, etc., but at present it is still insufficient in strength and durability, and film scraping occurs due to repeated use, resulting in sensitivity. It has a drawback that the image quality is deteriorated and the image quality is deteriorated. As a method of solving this, a method of using a polycarbonate resin as a binder resin of the charge transfer layer has been proposed.

On the other hand, as a developer used in an image forming method using these photoconductors, a two-component dry developer is widely and generally used. 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 of both 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. In order to form a good image, the toner particles must have a high triboelectric charging ability and a high fluidity. In order to meet such a demand, conventionally, an inorganic additive or the like has been added as an external additive.

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 mixing silica and titanium. In addition, JP-A-6
1-188546 and Japanese Patent Application Laid-Open No. 2-1581872 disclose mixing additives having different particle sizes. Further, in JP-A-61-249059, mixing of hydrophobic silica and hydrophilic silica is disclosed in JP-A-6-249059.
Japanese Patent Laid-Open No. 1-200533 discloses a mixture of a positive additive and a negative additive. Although the use of these additives has made the above-mentioned drawbacks of the prior art relatively ameliorated, it prevents the fluidity (aggregation) of the toner from being deteriorated during low-temperature fixing or high-speed copying, and improves the quality of the obtained image. It wasn't entirely satisfactory. .

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention does not cause toner aggregation at the time of low-temperature fixing or deterioration of toner fluidity, and further, scumming on the organic optical semiconductor. It is an object of the present invention to provide an image forming toner capable of forming a good image quality for a long period of time.

[0006]

According to the present invention, 100
Image formation including electrophotography, electrostatic printing, and electrostatic recording, in which the amount of film scraped per 0 sheets is 500Å or less, and an organic photosemiconductor containing a polycarbonate resin is used as a resin binder of the charge transfer layer. An image forming toner used in the method, wherein the toner has an average particle size of 5 to 10 μm and a softening temperature of 85 ° C. or lower, and contains at least one binder resin, a colorant, and a charge control agent as main components. Consisting of the base particles and, in the base particles, as a fluidity improver,
Two kinds of additives, an additive that increases the toner charge amount and an additive that decreases the toner charge amount as compared with the charge amount of the base particles alone, are added, and a release agent fatty acid carnauba wax having an acid value of 5 or less is used as a release agent. And / or a montan ester wax and / or an oxidized rice wax having an acid value of 10 to 30 is provided. That is, the image-forming toner of the present invention is obtained by transferring a toner image obtained by developing an electrostatic latent image on an organic photo-semiconductor onto a transfer paper and then exposing the untransferred toner remaining on the organic photo-semiconductor to a rubber-like elastic blade. A toner for use in an image forming method provided with a mechanism for removing by contact with a body, the toner being a low-temperature fixing toner having an average particle diameter of 5 to 10 μm and a softening temperature of 85 ° C. or less, and at least one binder resin, It is composed mainly of a release agent, a colorant, and a charge control agent. As a fluidity improving agent, there are two types of additives, an additive that increases the charge amount compared to the charge amount of the base toner alone and an additive that causes the charge amount to occur. An image forming toner characterized by being added.

OPC used in such an image forming method
Since it is always in contact with the rubber-like elastic blade, its surface is gradually scraped, sensitivity is lowered, and image quality is deteriorated. It is extremely useful to use a polycarbonate-based resin as a resin binder in the charge transfer layer in order to improve sensitivity deterioration due to scraping of OPC. OP
As shown in FIG. 1, a typical layer structure of C is such that a charge generation layer 2 and a charge transfer layer 3 are sequentially laminated on a conductive support 1. As a coating method, a spray coating method or the like is adopted so as not to disturb the charge generation layer and the charge transfer layer.
The charge transfer layer 3 can be formed by dissolving or dispersing a charge transfer substance and a resin binder in an appropriate solvent, applying the solution on the charge generation layer 2 and drying. If necessary, a plasticizer, a leveling agent, etc. may be added.

As the charge transfer substance, poly-N vinylcarbazole and its derivative, poly-γ-carbazoline ethylglutamate and its derivative, pyrene-formaldehyde condensate and its derivative, polyvinylpyrene, polyvinylphenanthrene, oxazole derivative,
Oxadiazole derivative, imidazole derivative, triphenylamine derivative, 9- (p-diethylaminostyrin) anthracene, 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones , An electron donating substance of an α-phenylstilbene derivative.

Examples of the resin binder include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-used in the charge generation layer.
Maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyacrylate resin, phenoxy resin, polycarbonate, cellulose acetate resin,
Thermoplastic or thermosetting resins such as ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, etc. However, in the present invention, it is important to use polycarbonate, and by using polycarbonate, the film abrasion amount can be suppressed to 500 Å or less per 1000 sheets. As the solvent at this time, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride or the like can be used.
The appropriate thickness of the charge transfer layer 2 is about 5 to 100 μm. The toner is generally a fine powder containing a binder resin and a colorant as main components. The toner must have a high triboelectric charging ability and a high fluidity.

In order to meet such requirements, a method of adding an inorganic additive (silicon oxide, titanium oxide, aluminum oxide, etc.) or the like as an external additive has been conventionally used. However, a toner using a resin or wax having a low softening point, such as a toner used for low-temperature fixing or high-speed copying for energy saving, has sufficient fluidity due to the adhesiveness of the resin or wax. Absent. As a means for improving such a point, it has been proposed to use two kinds of additives having different characteristics in combination. For example, as described in the above-mentioned prior art, in JP-A-60-136755, silicon oxide and titanium oxide are mixed and added. Also, JP-A-61-188546 and JP-A-2-1518.
In publications such as No. 72, additives having different particle sizes are mixed. Further, in JP-A-61-249059, hydrophobic silica and hydrophilic silica are mixed and added.
In JP 1-200533, a positive additive and a negative additive are mixed.

Although the above-mentioned defects of the toner have been eliminated by the action of these additives, the demand for higher image quality has recently been strengthened, and the toner particles tend to become finer accordingly. However, a fine toner of 5 to 10 μm has come to be used. These fine toners have much stronger cohesive force than conventional toners, and have extremely poor fluidity. Therefore, a fine toner using a resin or wax having a low softening point for low-temperature fixing often cannot obtain satisfactory fluidity even with the conventional improvements. Also,
The mixing of two kinds of additives by the method as in the prior art has a drawback that the charge amount changes greatly when the balance balance of the additives is disturbed.

When used in an image forming method using OPC in which polycarbonate is used for the charge transfer layer, more background stain is generated than when one kind of additive is used. The cause of this is not clear, but it is believed that a force acts between the polycarbonate, the base toner particles, and the two types of additives to prevent the rise of charging. As a result of intensive studies, the inventors of the present invention have found that the toner for image formation is added to and mixed with an additive which increases the charge amount of the toner as compared with the charge amount of the base toner alone. It has been found that by mixing an additive that reduces the charge amount, a toner that does not cause scumming can be obtained in an image forming method using OPC using polycarbonate. Further, an additive that increases the charge amount of the toner as compared with 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 a stable charge amount is always obtained. be able to.

Further, as an additive of the present invention, when an additive that increases charge is added, the charge amount of the base toner is set to 5
By using an additive that increases the content by up to 50%, a good toner having no background stain on the image can be obtained. Also, when an additive that reduces the charge amount is added, the charge amount of the base toner is 5
By using an additive that reduces the amount by 50%, a good toner having no background stain 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. 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 kinds are mixed. 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, and 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-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer styrene resin,
Vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenyl resin, epoxy resin, low molecular weight polyethylene, 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.

Further, 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, dyes and pigments such as carbon black, lamp black, aniline blue, phthalocyanine blue, phthalocyanine green, chrome yellow, quinacridone, rose bengal and triallylmethane dyes may be used alone or. It can be mixed and used. The amount of these colorants used is, relative to the binder resin,
It is usually 1 to 30 wt%, preferably 3 to 20 wt%. In the present invention, as a method of mixing the additive with the base toner, a conventionally known method may be used, such as a Henschel mixer,
It can be mixed by a device such as a speed kneader.

[0018]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 Preparation of Organic Photo-Semiconductor (Coating Liquid for Charge Generation Layer) Azo Pigment 4.5 parts

[Chemical 1] Methyl ethyl ketone 90 parts The above was mixed to obtain a charge generation layer coating liquid.

(Coating Liquid for Charge Transfer Layer) α-Phenylstilbene Charge Transfer Material 65 parts Polycarbonate 100 parts Silicon oil 0.1 part Tetrahydrofuran 800 parts Next, for the above charge generation layer on a cylindrical polyester vapor-deposited on aluminum. Spray coating the coating solution, 1 at 120 ℃
It was heated and dried for 0 minutes to form a charge generation layer having a thickness of about 0.2 μm. Next, the above charge transfer layer coating liquid is spray-coated on the charge generation layer and dried by heating at 120 ° C. for 20 minutes to form a charge transfer layer of about 20 μm, which is used in the present invention.
It was created.

Preparation of Toner Styrene-acrylic copolymer resin 84 parts (weight average molecular weight 180,000) Free fatty acid carnauba wax 5 parts (acid value 2) Carbon black (# 44: Mitsubishi Carbon Co.) 10 parts Quaternary ammonium salt The mixture consisting of 1 part was mixed using an extruder to obtain base particles having a deposited average particle size of 8.5 μm. When the charge amount of the obtained toner was measured by the blow-off method, it was 25 μc /
It was g. With respect to 1.0 Kg of the base particles, 3.0 g of silicon carbide fine powder (charge amount when added to mother toner is 10 μc / g) as an additive for reducing the charge amount and oxidation as an additive for reducing the charge amount Aluminum fine powder (charge amount when added to base toner is 42 μc / g) 2.0 g
Were simultaneously mixed with a Henschel mixer at 1000 rpm to obtain a toner of the present invention. The amount of charge of the obtained toner was 27 μc / g.

Preparation of Developer (Preparation of Carrier) Core substance (spherical ferrite having an average particle size of 50 μ) 100 parts Silicone resin (solid content 20% toluene solution) 20 parts Toluene 20 parts Coating solution on the surface of the core substance with the above formulation Coating was performed using a fluidized bed type coating device to obtain a carrier.

By using the toner prepared in (Preparation of developer) and the above carrier, a developer having a toner concentration of 3.0 wt% was prepared. To confirm the image quality (background stain) and charge stability of this toner, a commercially available electrophotographic copying machine (made by Ricoh Co., Ltd.
Recopy FT3300: The photoconductor was replaced with that of Example 1) to make 100,000 copies. The amount of charge at that time was measured, and the background stain was also evaluated. The results are shown in Table 1. As can be seen from Table 1, the image forming toner according to Example 1 of the present invention is excellent in both charging stability and background stain.

Comparative Example 1 1.0 kg of the base particles obtained in Example 1 was used as fine particles of silicon oxide (charge amount of 33 μc when added to the base toner).
/ G) 5.0 g using a Henschel mixer
The toner of Comparative Example 1 was obtained by mixing at rpm. As a carrier, a developer was prepared using the carrier of Example 1, and 100,000 copies were made in the same manner as in Example 1. The results are shown in Table 1. As can be seen from Table 1, the image-forming toner of Comparative Example 1 is inferior in both charging stability and background stain.

Example 2 1.0 Kg of the base particles obtained in Example 1 was added to silicon oxide fine powder (charge amount of 38 μc when added to the base toner).
/ G) and 2.0 g of silicon oxide fine powder (charge amount of 9 μc / g when added to the base toner) were simultaneously mixed at 1000 rpm using a Henschel mixer to obtain the toner of Example 2 of the present invention. Obtained. Using the carrier of Example 1, 100,000 copies were made in the same manner as in Example 1. The results are shown in Table 1. As can be seen from Table 1, the image-forming toner of Example 2 is excellent in both charging stability and background stain.

Example 3 To 1.0 Kg of the base particles of Example 1, silicon oxide fine powder (charge amount when added to the base toner is 38 μc / g)
2.0 g of the above is added and mixed at 1000 rpm with a Henschel mixer first, and then 2.0 g of silicon oxide fine powder (charge amount when added to the base toner is 9 μc / g) is simultaneously added with a Henschel mixer at 1000 rpm. The toner of Example 3 of the present invention was obtained by adding and mixing. Using the carrier of Example 1, 100,000 copies were made in the same manner as in Example 1. The results are shown in Table 1. As can be seen from Table 1, the image forming toner of Example 3 is excellent in both charging stability and background stain.

Example 4 1.0 kg of base particles of Example 1 was used as fine particles of silicon oxide (charge amount when added to base toner was 38 μc / g).
2.0 g of the above was first added and mixed with a Henschel mixer at 1500 rpm, and then 2.0 g of silicon oxide fine powder (charge amount when added to the base toner was 9 μc / g) was simultaneously added with a Henschel mixer at 1000 rpm. Addition and mixing were carried out to obtain a toner of Example 4 of the present invention. Using the carrier of Example 1, 100,000 copies were made in the same manner as in Example 1. The results are shown in Table 1. As can be seen from Table 1, the image forming toner of Example 4 is excellent in both charging stability and background stain.

Example 5 Silicon oxide fine powder (charge amount when added to the base toner is 38 μc / g) relative to 1.0 Kg of the base particles of Example 1.
2.0 g of the above was first added and mixed with a Henschel mixer at 1500 rpm, and then 2.0 g of silicon oxide fine powder (charge amount when added to the base toner was 19 μc / g) was simultaneously added with a Henschel mixer at 1000 rpm. Addition and mixing were carried out to obtain a toner of Example 5 of the present invention. Using the carrier of Example 1, 100,000 copies were made in the same manner as in Example 1. The results are shown in Table 1. As can be seen from Table 1, the image forming toner of Example 5 is excellent in both charging stability and background stain.

Example 6 To 1.0 Kg of the base particles of Example 1, silicon oxide fine powder (charge amount when added to the base toner was 31 μc / g)
2.0 g of the above was first added and mixed with a Henschel mixer at 1500 rpm, and then 2.0 g of silicon oxide fine powder (charge amount when added to the base toner was 19 μc / g) was simultaneously added with a Henschel mixer at 1000 rpm. Addition and mixing were performed to obtain a toner of Example 6 of the present invention. Using the carrier of Example 1, 100,000 copies were made in the same manner as in Example 1. The results are shown in Table 1. As can be seen from Table 1, the image forming toners of Examples are excellent in both charging stability and background stain.

[0030]

[Table 1]

[0031]

As described above, in the present invention, by adding a specific different type of fluidity improver and a specific release agent to the base toner particles, the stability is good for a long period of time and low temperature fixing is performed. An image forming toner having excellent properties can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing a layer structure of an organic photoconductor to which an image forming toner of the present invention is applied.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03G 13/00 G03G 9/08 365 371 375 381 (72) Inventor Toshio Fukagai 1-chome Nakamagome, Ota-ku, Tokyo No. 3-6 In Ricoh Co., Ltd.

Claims (3)

[Claims] 1. An electrophotographic method, an electrostatic printing method, an electrostatic recording method, wherein the amount of film abrasion per 1000 sheets is 500Å or less, and an organic optical semiconductor containing a polycarbonate resin is used as a resin binder of a charge transfer layer. An image forming toner used in an image forming method including a method, the toner having an average particle size of 5 to 10 μm and a softening temperature of 85 ° C. or lower, and at least one binder resin, a colorant, and a charging agent. An additive that is composed of base particles containing a control agent as a main component, and that is added to the base particles as a fluidity improving agent to increase the toner charge amount compared to the charge amount of the base particles alone and to reduce the toner charge amount. Of the free fatty acid carnauba wax having an acid value of 5 or less and / or a montan ester wax and / or an acid value of 10 to 3 as a releasing agent.
An image forming toner comprising 0 of oxidized rice wax. 2. The toner for image formation according to claim 1, wherein the two kinds of additives are silica. 3. The additive for decreasing the toner charge amount is added and mixed after the additive for increasing the toner charge amount compared to the charge amount of the base toner alone is added and mixed. 1. The image forming toner according to 1.