JP2704593B2 - Electrophotographic toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner, and more particularly, to an electrophotographic toner for a copying machine or a printer which employs heat roll fixing.

[0002]

2. Description of the Related Art In recent years, as copiers and printers using an electrophotographic system have spread, the energy consumption (power consumption) has been reduced mainly for the purpose of dissemination to homes and multifunctional copiers or printers. It is desired to increase the speed for the purpose of spreading to the so-called gray area located at the boundary between the printing machine and the copying machine, or to reduce the roll pressure for simplifying the fixing roll to reduce the machine cost. Yes,
In addition, as copiers have become more sophisticated, since copiers equipped with a two-sided copy function and an automatic document feeder have become widespread, the fixing temperature of electrophotographic toner used in copiers and printers is low, and the There is a demand for an electrophotographic toner that has excellent offset properties and has excellent fixing strength to transfer paper in order to prevent the occurrence of stains during duplex copying and the occurrence of stains in an automatic document feeder. In response to the above demands, the prior art proposes a binder resin having an improved molecular weight or molecular weight distribution as described below.

Specifically, attempts have been made to lower the molecular weight of the binder resin and lower the fixing temperature. However, the lowering of the molecular weight lowers the melting point but at the same time lowers the melt viscosity, so that there has been a problem that an offset phenomenon to the fixing roll occurs. In order to prevent this offset phenomenon, a method of widening a low molecular weight region and a high molecular weight region of the molecular weight distribution of the binder resin, or a method of cross-linking a polymer portion has been performed. However, in this method, the glass transition temperature of the resin must be lowered in order to have sufficient fixability, and it is inevitable that the storage stability of the toner is impaired. Further, when the amount of the low-molecular-weight portion of the binder resin is increased, the toner itself becomes brittle, and stains during double-sided copying and stains in the automatic document feeder have occurred.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic apparatus which can fix at a low fixing temperature, does not cause any practical problem in offset properties, and has excellent fixing strength to transfer paper. To provide a toner for use.

[0005]

According to the present invention, there is provided an electrophotographic toner comprising at least hydrazide and an epoxy resin or an acrylic resin having a glycidyl group.

Hereinafter, the present invention will be described in detail. The hydrazide in the present invention is used as a crosslinking agent for crosslinking an epoxy group. The general formula is represented by RCONHNH ₂ , where R represents an alkyl group, an aryl group, or the like. Examples of the hydrazide used in the present invention include 1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin (trade name, manufactured by Ajinomoto Co .; Amicure VDH, melting point 120 ° C.) having the following structural formula:

Embedded image

7,11-octadecadien-1,18-dicarbohydrazide having the following structural formula (manufactured by Ajinomoto Co.)
Trade name: AMICURE UDH, melting point 160 ° C) and

Embedded image H ₂ NNHCO (CH ₂ ) ₆ CH = CH (CH ₂ ) ₂ CH = CH (CH ₂ ) ₆ CONHNH ₂ Eicosane diacid dihydrazide having the following structural formula (trade name, manufactured by Ajinomoto Co .; Amicure LDH, melting point 180) ° C).

Embedded image H ₂ NNH—CO— (CH ₂ ) ₁₈ —CO—NHNH ₂ 1,3-bis (hydrazinocarboethyl) —having the lowest melting point among the above hydrazides and having the best transparency after crosslinking. 5
-Isopropylhydantoin is most preferred. If the melting point is low, the kneading temperature for the cross-linking reaction may be low, and the kneading time may be short, which is preferable. Further, colorless and transparent are preferable because they do not hinder the color tone when a color toner is used. The addition amount is usually 5 to 50 parts by weight based on 100 parts by weight of the epoxy group-containing resin.

The hydrazide used in the present invention is a crosslinking agent for an epoxy group, and is considered to have the following reaction mechanism.

Embedded image

The epoxy resin used in the present invention is preferably a bisphenol A type epoxy resin. A specific example is a product name of Yuka Shell Epoxy Co., Ltd .; Epicoat 1
004, 1007, 1009 and the like.

[0010] As the acrylic resin having a glycidyl group, a homopolymer or copolymer of glycidyl (meth) acrylate is used. Monomers for synthesizing copolymers include styrene, (meth) acrylamide, (meth) acrylonitrile, (meth) acrylate such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate And ethyl methacrylate, propyl methacrylate, butyl methacrylate and the like.

In the present invention, a styrene copolymer is preferably used as a binder resin as a main component other than the epoxy resin or the acrylic resin. The styrene copolymer is obtained by synthesizing the following monomers by a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, a bulk polymerization method, or the like.
As monomers, styrenes such as styrene, α-methylstyrene and chlorostyrene, acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and octyl acrylate,
Examples thereof include methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, stearyl methacrylate, and glycidyl methacrylate. Other copolymerization components include acrylonitrile, maleic acid, maleic ester, methyl methacrylate, methyl acrylate, vinyl chloride, vinyl acetate, vinyl benzoate, vinyl methyl ketone, vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether,
A vinyl monomer such as vinyl isobutyl ether may be contained at 30% by weight or less based on the polymer. The amount of the epoxy resin or the glycidyl group-containing acrylic resin in the total binder resin is preferably 5 to 50% by weight.

In the present invention, a polyester resin may be used as a binder resin component in addition to the styrene copolymer. As the polyester resin, a resin generally used for a toner can be used. Among them, as the alcohol component, an ethylene oxide adduct or a propylene oxide adduct of bisphenol A is preferable. As the acid component, fumaric acid, phthalic acid and the like are preferable. As the binder resin of the electrophotographic toner of the present invention, a resin such as a polyethylene resin, a silicone resin, a polyamide resin, or a polyurethane resin may be blended in addition to the copolymer.

The toner for electrophotography of the present invention preferably contains a vegetable wax in order to impart low-temperature fixability and offset resistance. Plant waxes include candelilla wax, carnauba wax, rice wax,
Tree wax and the like. In the toner of the present invention, in addition to the above components, a colorant, a magnetic substance, and a property improving agent such as a charge controlling agent and a fluidizing agent can be used.

As the coloring agent, carbon black,
Nigrosine dye, aniline blue, chaco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, mixtures thereof, and the like. it can. These colorants need to be contained in a sufficient ratio to form a visible image having a sufficient concentration, and usually a ratio of about 1 to 20 parts by weight based on 100 parts by weight of the binder resin. Is done.

As the magnetic material, ferromagnetic metals or alloys such as ferrite and magnetite, cobalt, and nickel, or compounds containing these elements, or compounds containing no ferromagnetic elements, or suitable heat treatments are not included. Alloys that become ferromagnetic when applied, such as manganese-copper-aluminum, manganese-copper-tin, and other alloys of the type called Heusler alloys containing manganese and copper, or chromium dioxide, and the like. .
These magnetic materials are uniformly dispersed in the binder resin in the form of fine powder having an average particle size of 0.1 to 1 micron. The content is 20 to 70 parts by weight, preferably 40 to 70 parts by weight, per 100 parts by weight of the toner.

Examples of the property improving agent include a charge control agent, an anti-offset agent, a lubricant for improving fluidity, and the like. As for the melting characteristics of the toner, the melting start temperature of the toner should be 60 ° C. or higher and 100 ° C. or higher in order to improve the fixability at a lower temperature.
C. or less is preferred. If the temperature is higher than 100 ° C., the fixing property is not sufficient. The melting start temperature means the temperature at which the plunger starts to fall. Measuring machine; Koka type flow tester CF-500 manufactured by Shimadzu Corporation Measurement conditions: Plunger: 1 cm ² Die diameter: 1 mm Die length: 1 mm Load: 20 kgF Preheating temperature: 50 to 80 ° C Preheating time: 300 sec Heating rate : 6 ° C / min The toner for electrophotography of the present invention is mixed with a carrier composed of ferrite powder, iron powder and the like to form a two-component developer.
When a magnetic substance is contained, it may be used as it is as a one-component developer without mixing with a carrier for developing an electrostatic image, or may be mixed with a carrier and used as a two-component developer. Further, the present invention can be applied to a non-magnetic one-component developing method.

[0017]

The reason why the above hydrazide is contained in the electrophotographic toner of the present invention is as follows. That is, as a means for improving the fixing property, the melting start temperature or the melt viscosity is lowered by reducing the molecular weight of the styrene or polyester resin. Alternatively, an effect of anchoring to paper has been provided by lowering Tg. However, in this method, the resin strength is reduced due to the reduction in the molecular weight of the resin, and the toner layer of the fixed image is damaged by mechanical friction. Or was. However, by incorporating hydrazide, which is a curing agent for an epoxy group, into the toner and crosslinking during melt-kneading, the melt viscosity of the toner increases, and offset of the fixing roller during fixing can be prevented. Further, since the strength of the toner layer after fixing is improved, the weakness of the strength of the binder resin as the main component can be improved. The adjustment of the melt viscosity by crosslinking can be performed by the amount of the curing agent, and can also be performed by adding a vegetable wax.

[0018]

【Example】

Synthesis Example 1: Synthesis of glycidyl methacrylate (GMA) homopolymer 253 g of methyl ethyl ketone (MEK) was placed in a flask and heated to 80 ° C. Under a nitrogen stream, a mixture of 142 g of GMA and 2.11 g of benzoyl peroxide (BPO) is added dropwise at a constant rate over 3 hours. 80 after dripping
Continue the reaction at 2 ° C. for 2 hours. MEK 31g and BPO 0.3
Add 1 g of solution. Further, the polymerization reaction is performed at 80 ° C. for 5 hours. After cooling, the product is placed in 2414 g of MEK. This solution was used for methanol 142
Slowly drop into 00g. The precipitated polymer is filtered off,
Drying under reduced pressure gives the desired product.

Synthesis Example 2: Synthesis of copolymer of GMA and methyl methacrylate (MMA) A mixed solution of xylene-MEK and 1 mol% of BPO are charged into a flask and heated to 80 ds. GMA 25 mol%,
A mixture of 75 mol% of MMA is added dropwise over 3 hours. The reaction is continued for 2 hours after the addition. 0.15 mol% of BPO is charged as a 10% solution of the above solvent. The polymerization is continued for another 5 hours. The solution is slowly dropped into methanol, which is being marketed vigorously. The precipitated polymer is separated by filtration and dried under reduced pressure to obtain the desired product.

Hereinafter, the present invention will be described based on examples.
In the examples, parts are parts by weight. Example 1 Weight average molecular weight 8.3 × 10 ³ and number average molecular weight 4.1
A copolymer of × 10 ³ styrene 80 parts-butyl acrylate 20 parts was obtained. The styrene copolymer and other raw materials were mixed in a super mixer at the following mixing ratio,
After melt-kneading, the resulting mixture was pulverized and classified to obtain particles having an average particle diameter of 11 μm, and then 0.3 parts of hydrophobic silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was adhered to the surface of the particles using a Henschel mixer. A negatively chargeable electrophotographic toner of the present invention was obtained.

The styrene copolymer 100 parts Epoxy resin 20 parts (trade name, manufactured by Yuka Shell Co .; Epicoat 1004) Hydrazide 8 parts (trade name, manufactured by Ajinomoto Co., Amicure VDH) Carbon black 6.5 parts (Mitsubishi MA-100, manufactured by Kasei Kogyo Co., Ltd. 2 parts of chromium-containing dye (S-34, manufactured by Orient Chemical Co., Ltd.) 5 parts of wax (melting start temperature: 71.1 ° C.) 5 parts of polypropylene 3 parts (Sanyo Chemical Industries, Ltd.) (Trade name of Viscole 330P)

Example 2 An electrophotographic toner was obtained in the same manner as in Example 1 with the following formulation. Styrene copolymer of Example 1 100 parts Glycidyl group-containing acrylic resin 20 parts (Copolymer obtained in Synthesis Example 2) Hydrazide 8 parts (Ajinomoto Co., trade name; Amicure VDH) Carbon black 6.5 parts (Mitsubishi MA-100 manufactured by Kasei Kogyo Co., Ltd. 2 parts of chromium-containing metal dye (manufactured by Orient Chemical Co., Ltd .; S-34) Rice wax (melting initiation temperature: 71.1 ° C.) 5 parts Polypropylene 3 parts (Sanyo Chemical Industries, Ltd.) (Trade name of Viscole 330P)

Example 3 An electrophotographic toner was obtained in the same manner as in Example 1 with the following composition. 100 parts of the styrene-based copolymer of Example 1 20 parts of an epoxy resin (trade name, manufactured by Yuka Shell Co .; Epicoat 1004) 10 parts of hydrazide (trade name, manufactured by Ajinomoto Co., Amicure UDH) 6.5 parts of carbon black (Mitsubishi MA-100 manufactured by Kasei Kogyo Co., Ltd. 2 parts of chromium-containing metal dye (manufactured by Orient Chemical Co., Ltd .; S-34) Rice wax (melting initiation temperature: 71.1 ° C.) 5 parts Polypropylene 3 parts (Sanyo Chemical Industries, Ltd.) (Trade name of Viscole 330P)

Example 4 An electrophotographic toner of the present invention was prepared in the same manner as in Example 3 except that hydrazide (trade name; Amicure UDH) in Example 3 was changed to hydrazide (trade name; LDH). Comparative Example 1 An electrophotographic toner for comparison was obtained in the same manner as in Example 1 except that hydrazide was not contained.

Next, the toners obtained in the above Examples and Comparative Examples were tested for fixing strength, image density, background fog, non-offset temperature range and melting start temperature. 1) Fixing strength First, a developer was prepared by mixing 3 parts of each electrophotographic toner obtained in the above Examples and Comparative Examples with 100 parts of a non-coated ferrite carrier (trade name: FL-1020, manufactured by Powder Tech). . Next, using the developer, a commercial copier (trade name: SF-9800, manufactured by Sharp Corp.)
A plurality of belt-shaped unfixed images measuring 2 cm in length and 5 cm in width were prepared on the copy paper of Example 1. Next, a fixing device comprising a heat fixing roll having a surface layer formed of Teflon and a pressure fixing roll having a surface layer formed of silicone rubber was rolled at a roll pressure of 5 kg / cm ^2.
And the roll speed was adjusted to 100 mm / sec, the set temperature of the heat fixing roll was set to 130 ° C., and the toner image of the transfer paper having the unfixed image was fixed. Then, the formed fixed image was rubbed with a cotton pad, and the fixing strength was calculated by the following equation. 2) Non-offset temperature region Image density of fixed image after rubbing / image density of fixed image before rubbing × 100 (%) 2) Non-offset temperature region The temperature of the heat fixing roll is changed from 100 ° C. to 200 ° C. The temperature at which the fixing offset occurs was investigated.

3) Image Density and Background Fog Continuous copying of up to 10,000 sheets was performed using a commercially available copying machine (trade name: BD3801 manufactured by Toshiba Corporation) using the above-mentioned developers. The evaluation of the ground cover was performed. Image density; Macbeth reflection densitometer RD-914 Ground fog; Color difference meter MODEL Z 100 manufactured by Nippon Denshoku Co., Ltd.
The 1DP numerical value indicates the difference in whiteness between the transfer paper before copying and the non-image area after copying. 4) Melting start temperature The measurement was performed under the measurement conditions described above. Table 1 shows the results of the examples and the comparative examples obtained by the above-described tests.

[0027]

[Table 1]

As is clear from Table 1, the electrophotographic toner of the present invention has a fixing strength of 80% or more and an offset width of 55 even when the temperature of the heat fixing roll is as low as 130 ° C.
~ 70 ° C, which was good. On the other hand, it was confirmed that the comparative electrophotographic toner had a fixing offset and had a practical problem.

[0029]

The toner for electrophotography of the present invention has sufficient fixing strength even when the temperature of the heat fixing roll is low, and can reduce power consumption when applied to a copying machine or a printer. In addition, effects such as a reduction in machine cost due to a reduction in roll pressure and an increase in copying speed can be obtained.

Claims (4)

(57) [Claims] 1. An electrophotographic toner comprising at least hydrazide and an epoxy resin or an acrylic resin having a glycidyl group. 2. The electrophotographic toner according to claim 1, wherein the hydrazide is 1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin. 3. The electrophotographic toner according to claim 1, further comprising a vegetable wax. 4. A melting start temperature of the toner is 60 ° C. or more and 10 or more.
2. The electrophotographic toner according to claim 1, wherein the temperature is 0 ° C. or lower.