JPH0882953A - Electrophotographic toner and manufacturing method thereof - Google Patents

Abstract

PURPOSE: To prevent blocking by coating the surfaces of toner matrix particles with a UV- or electron beam-curing acrylate. CONSTITUTION: The surfaces of toner matrix particles contg. a bonding resin and a colorant are coated with a UV- or electron beam-curing acrylate. A (meth)acrylic ester monomer forming a styrene-(meth)-acrylic ester copolymer used in the toner matrix particles is, e.g. methyl acrylate or ethyl acrylate. The colorant is, e.g. carbon black or a nigrosine dye. The UV- or electron beam-curing acrylate may be used in combination with a photopolymerizable monomer so as to regulate the viscosity or crosslinking density. The monomer is, e.g. a monofunctional monomer such as 2-hydroxyethyl acrylate or a bifunctional monomer such as 1,6-hexanediol acrylate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner, particularly an electrophotographic toner for heat roll fixing, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a developing method used for electrophotography, an insulating fine powder containing a binder resin as a main component, that is, a toner, and the toner are charged by friction with a magnetic carrier, Two-component method that develops the electrostatic latent image formed on it with a magnetic brush, magnetic one-component magnetic brush development method that develops only with magnetic toner, non-magnetic toner is formed in a thin layer on the developing sleeve, and contacts the photoconductor Alternatively, a so-called non-magnetic one-component developing method of developing in a non-contact manner is known.

The toner developed by these methods is fixed on a transfer paper by a fixing process. When the heat fixing method using a heat roll, oven, flash, etc. is used as the fixing method, the melting start temperature of the toner is an important factor for maintaining the fixing performance, and the reduction of heat energy such as higher speed and lower temperature. Therefore, it is preferable that the melting start temperature of the toner is low. However, when the melting start temperature of the toner is lowered, there is a problem that the blocking property is deteriorated as the temperature lowers. That is, blocking by storing the toner at a high temperature, blocking of the toner on the carrier by friction with the carrier in the developing device, blocking of the recovered toner in the cleaning process, and the like are applicable. Further, particularly in the case of the non-magnetic one-component system, the toner is rubbed on the sleeve by the blade for forming the toner layer to be charged and the layer is formed, so that stress such as heat or pressure is applied to the toner, and the toner itself is applied. If there is no heat resistance or pressure resistance, blocking of the toner with respect to the sleeve or blade occurs, and the developability is greatly impaired.

In the conventional toner, a binder resin such as polystyrene or polyester is mixed with a coloring agent such as carbon black and magnetic powder, a dye, etc. at an appropriate ratio, and the mixture is melted and kneaded, and then finely adjusted to 1 to 25 μm. A pulverized product is used, and in order to prevent the blocking, the glass transition temperature of the toner is designed to be high, and the blocking and fusion are very good, but the fixing performance is poor and the temperature is lower. Is required to be established.

As a method for improving the blocking property, there is known a surface modification method in which a fluidizing agent is externally added to the surface of the toner, or an organic material or an inorganic material is mechanically attached. However, it is difficult for these methods to completely coat the surface of the toner particles with the material particles. Therefore, the fine powder adhering to the surface of the toner is melted again and coated on the surface of the toner and then solidified, or the surface of the toner is coated with a liquid material and then solidified. It poses a problem that is necessary, complicated and takes a long time.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention provides a toner having a low softening point that can be fixed at a low temperature, which is a toner having a long life and which does not cause blocking. In addition, the objective is to simply and harden and coat in a short time.

[0007]

In the electrophotographic toner according to the present invention, the surface of toner mother particles containing at least a binder resin and a colorant is coated with an acrylate which is cured by ultraviolet rays or electron beams, and is exposed to ultraviolet rays or The above object was achieved by irradiating with an electron beam.

Since the toner mother particles of the electrophotographic toner of the present invention contain at least a binder resin and a colorant and are mostly composed of the binder resin in a weight ratio, any binder resin may be used. Whether or not it has a great influence on the melting start temperature of the toner. As the binder resin used in the toner mother particles of the electrophotographic toner of the present invention, conventionally used polystyrene, styrene-acrylic acid ester copolymer, polyester, epoxy resin and the like can be used. In order to lower the melting start temperature of the toner mother particles, it is preferable to use a resin having a molecular weight as small as possible. A resin having a low molecular weight has a low melting start temperature as compared with a resin having a high molecular weight, and a resin having a low glass transition point (Tg) also has a low melting start temperature as compared with a resin having a high glass transition temperature, and thus is preferably used. As such a resin, for example, a styrene- (meth) acrylic acid ester copolymer having a number average molecular weight of 9000 or less and a glass transition point of 60 ° C. or less is preferable, and such a resin has a melting start temperature of 60 ° C. or more. It is 100 ° C. or less.

The monomer of the (meth) acrylic component constituting the styrene / (meth) acrylic acid ester copolymer used in the toner mother particles of the present invention is, for example, methyl acrylate, ethyl acrylate, acrylic acid. n-Butyl, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-chloroacrylic Methyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, methacrylic acid Two
-Ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, etc. can be mentioned.

As described above, by selecting the binder resin to be used, the melting start temperature of the toner mother particles is lower than the conventional melting start temperature of 110 ° C., more specifically 1
The temperature can be controlled at 00 ° C or lower. However, if the melting start temperature of the binder resin is unnecessarily lowered, that is, if the melting start temperature is lower than 60 ° C., the toner softens in the summer, which is not preferable for storage stability.
Therefore, the melting start temperature is preferably 60 ° C. or higher, which is higher than room temperature. Therefore, the melting start temperature of the binder resin used in the electrophotographic toner mother particles of the present invention is set to a temperature at which the toner can be fixed on the paper at a low temperature and which is preferable for storage stability, that is, 60 ° C. or higher and 100 ° C. or lower. Preferably.

The colorant used in the toner mother particles of the present invention includes carbon black, nigrosine dye,
Examples thereof include aniline blue, chalco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachide green oxalate.

Further, as the charge control agent, the charge control agent conventionally used can be used in the toner mother particles of the present invention. Examples thereof include nigrosine-based dyes, quaternary ammonium salts, monoazo-based metal complex dyes, triphenylmethane-based control agents, resin-based control agents and the like.

The UV-curable or electron beam-curable acrylate referred to in the present invention is a photopolymerizable prepolymer composed of an oligomer having a (meth) acryloyl group in the molecule,
Oligoether acrylate, oligoester acrylate, urethane acrylate, epoxy acrylate,
Aliphatic acrylates, alicyclic acrylates, polyester acrylates and the like are applied. Commercial item, eg B
ASF LAROMAR PO83F, PO84F, L
R8869 (each of which is an oligoether acrylate), Photomer 4160 (aliphatic acrylate) manufactured by San Nopco, Nopcomer 4210 (alicyclic acrylate), Photomer 5018 (polyester acrylate), or the like can also be used. These UV curable or electron beam curable acrylates include diphenyl disulfide, benzoin alkyl ether, benzophenone, acetophenone, 2-hydroxy-2-methyl-1.
-A photopolymerization initiator such as phenylpropan-1-one is used in combination.

The UV-curable or electron beam-curable acrylate of the present invention may be used in combination with the following photopolymerizable monomer for the purpose of adjusting its viscosity or crosslinking density. That is, of these monomers, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, phenoxyethyl acrylate, etc. are used as monofunctional monomers, and 1,6-functional compounds are used as bifunctional acrylates.
Hexanediol acrylate, ethylene oxide-modified neopentyl glycol diacrylate, ethylene oxide-modified bisphenol A diacrylate, and the like, and polyfunctional monomers include trimethylol propane triacrylate, ethylene oxide-modified trimethylol propane triacrylate, pentaerythritol tetraacrylate, and diacrylate. Examples include pentaerythritol hexaacrylate.

In the present invention, the electron beam used for irradiation is
In addition to electron beams in a narrow sense, ionizing radiation such as neutron rays and γ rays can be used, but electron beams in a narrow sense are preferable in terms of manufacturing efficiency. Next, as an electron beam accelerator used for electron beam irradiation, a Van de Graaff type scanning system, a double scanning system or a curtain beam system can be adopted, but a curtain beam system which can obtain a large output at a relatively low cost is preferable. Further, as the electron beam irradiation conditions, the electron beam irradiation is preferably an accelerating voltage of 50 to 1000 KV, more preferably 100 to 300 KV, and an absorbed dose is preferably 0.5 to.
It is 20 Mrad, more preferably 2 to 15 Mrad. When the accelerating voltage is 50 KV or less, the energy transmission amount is insufficient, and when it exceeds 1000 KV, the energy efficiency involved in the polymerization is reduced, which is not economical. Further, if the absorbed dose is 0.5 Mrad or less, the curing reaction or the reaction of the monomer is insufficient, and if it exceeds 20 Mrad, the energy efficiency is lowered. When electron beam irradiation is performed in air, alienation hardening due to oxygen is observed, so it is important to perform irradiation in an inert gas such as N ₂ gas, He gas, CO ₂ gas or the like. As a light source of the ultraviolet irradiation device, there are a mercury lamp, a metal halide lamp, a high power metal halide lamp and the like.

The toner for electrophotography of the present invention can be obtained by coating the surface of toner mother particles with a UV-curable or electron beam-curable acrylate and then irradiating it with UV rays or an electron beam. That is, a binder resin, a colorant, a charge control agent,
If necessary, other additives and the like are mixed in a desired mixing ratio and melt-kneaded. Then, by cooling, the solidified product is pulverized and classified to obtain toner mother particles. It is also possible to use a polymerizable resin as the binder resin and mix the above materials at the time of polymerization. Thus, the toner formed by mixing the materials at the time of polymerizing the polymerizable resin as the binder resin is called a so-called polymerizable toner. Next, the obtained toner mother particles are coated with an ultraviolet curable or electron beam curable acrylate, and then irradiated with an ultraviolet ray or an electron beam to be cured to obtain the electrophotographic toner of the present invention.

The following method can be exemplified as a method for forming a coating film of ultraviolet curable or electron beam curable acrylate on the surface of toner mother particles. In the method, an ultraviolet curable or electron beam curable acrylate and a photopolymerization initiator are sprayed on the toner mother particles in a high-speed stirrer, and the toner mother particles are uniformly attached to the surface of the toner mother particles. Then, during stirring, the acrylate is cured by irradiation with ultraviolet rays or electron beams. When the UV-curable or electron beam-curable acrylate is dissolved in an alcohol solvent for adjusting the viscosity, it is preferable to evaporate the solvent by heating and stirring before irradiation with the UV ray or the electron beam. As a method for heating the stirrer, the temperature inside the stirrer may be maintained by blowing hot air into the stirrer or by raising the jacket temperature of the stirrer.

In summary, in order to obtain the toner of the present invention, the ultraviolet curable or electron beam curable acrylate and the polymerization initiator are uniformly adhered to the toner surface while the toner mother particles are stirred in a high speed stirrer, and ultraviolet or electron It can be carried out by a manufacturing method of irradiating a ray to cure. In the present invention, it is preferable to coat 100 parts by weight of the toner mother particles with an ultraviolet ray curable or electron beam curable acrylate so as to be 0.1 part by weight or more and 5 parts by weight or less in terms of solid content. In this case, if the amount is less than 0.1 parts by weight, the effect of coating the ultraviolet-curable or electron beam-curable acrylate will not be exhibited, and thus blocking may occur. On the other hand, when the amount is more than 5 parts by weight, the fixing property of the toner may be deteriorated, and it may take time and effort to heat and dry a large amount of the coating layer, and the production efficiency may be deteriorated.

The melting start temperature specified in the present invention is
It means the temperature at which the plunger starts to fall under the measurement conditions shown below. Measuring machine: Shimadzu's advanced flow tester CFT-
500 Measurement conditions: Plunger 1 cm ² Die diameter 1 mm Die length 1 mm Load 20 KgF Preheating temperature 50-80 ° C Preheating time 300 sec Heating rate 6 ° C / min

The electrophotographic toner of the present invention may be sprinkled with a fluidizing agent such as hydrophobic silica, colloidal silica or resin fine particles. [Function] The electrophotographic toner of the present invention comprises an ultraviolet curable or electron beam curable acrylate on the surface of toner mother particles containing a binder resin having a melting start temperature of 60 ° C. or higher and 100 ° C. or lower and a colorant. The toner does not cause blocking even if the binder resin, which occupies most of the toner weight, is placed in an environment where the temperature rises above the glass transition temperature due to heat. In the electrophotographic toner of the present invention, a coating film of an ultraviolet curable or electron beam curable acrylate is provided on the surface of toner mother particles containing at least a binder resin and a colorant, and the melting start temperature is 6
When the temperature is 0 ° C. or higher and 100 ° C. or lower, the fixing temperature can be made considerably lower than before without causing blocking.

[0021]

The present invention will be described in more detail based on the following examples. In the examples, "part" means "part by weight",
"%" Means "% by weight". In this example, first, toner base particles (A) having the following composition were prepared. -Styrene-acrylic acid ester copolymer resin 100 parts (monomer composition; styrene / butyl acrylate) High molecular weight Mw = 3.0 × 10 ⁶ Mn = 1.0 × 10 ⁶ Low molecular weight Mw = 7.5 × 10 ³ Mn = 2.7 × 10 ³ Low molecular weight product: High molecular weight product = 90: 10 ・ Carbon black 7 parts (trade name; MA-100 manufactured by Mitsubishi Kasei Co.) ・ Quaternary ammonium salt 2 parts (Orient Chemical Industry Co., Ltd.) Product name: P-51) Polypropylene 3 parts (Product name: Sanyo Kasei Kogyo Co., Ltd .: Viscole 330P)

To prepare the toner mother particles (A),
The raw materials having the above composition were mixed with a super mixer, melt-kneaded, and then pulverized and classified to obtain negatively chargeable toner mother particles having an average particle diameter of 11 μm. The melting start temperature of the obtained toner mother particles is 92 ° C.

Example 1 UV curable amine-modified oligoether acrylate (BASF) was added to 100 parts of the toner mother particles (A).
0.15 parts of Lalomer PO83F) manufactured by the same company is spray-added, stirred in a Henschel mixer, and after the acrylate is uniformly attached to the surface of the toner mother particles, a device using a mercury lamp (80 W / cm) as a light source. UV irradiation for 3 minutes to cure the acrylate. The photoinitiator used at this time was 2-hydroxy-2-methyl-1-phenylpropan-1-one (manufactured by E. MERCK, trade name: Dar.
ocur1173), the addition amount is 3% with respect to Laromer PO83F.

Example 2 To 100 parts of the toner mother particles (A), Laromer P was added.
The same operation as in Example 1 was performed except that 0.5 part of O83F was added by spraying.

Example 3 To 100 parts of the toner mother particles (A), Laromer P was added.
The same operation as in Example 1 was performed, except that 2.0 parts of O83F was added by spraying.

Example 4 To 100 parts of the toner mother particles (A), Laromer P was added.
The same operation as in Example 1 was performed except that 5.0 parts of O83F was added by spraying.

Example 5 To 100 parts of the toner mother particles (A), a UV-curable acrylate (manufactured by San Nopco: acrylate content 33%, photoinitiator benzophenone 3%) using isopropyl alcohol as a solvent was used. The same operation as in Example 1 was performed, except that 0 part of the mixture was added by spraying and the mixture was heated and stirred at a jacket temperature of 40 ° C. for 5 minutes before being irradiated with ultraviolet rays.

Example 6 The same operation as in Example 1 was carried out except that 0.05 part of UV curable acrylate PO83F was spray-added to 100 parts of the toner mother particles (A).

Example 7 The same operation as in Example 1 was carried out except that 8.0 parts of UV curable acrylate PO83F was spray-added to 100 parts of the toner mother particles (A).

Comparative Example 1 The same operation as in Example 1 was carried out except that the ultraviolet curable acrylate PO83F and the photoinitiator were not added to 100 parts of the toner mother particles (A), and the electrophotographic toner for comparison was used. Got

Comparative Example 2 Toner mother particles (B) were prepared with the following composition in the same process as in Example 1. -Styrene-acrylic acid ester copolymer resin 100 parts (monomer composition; styrene / butyl acrylate) High molecular weight Mw = 3.0 × 10 ⁶ Mn = 1.0 × 10 ⁶ Low molecular weight Mw = 7.5 × 10 ³ Mn = 2.7 × 10 ³ Low molecular weight product: High molecular weight product = 65: 35 ・ Carbon black 7 parts (trade name; MA-100 manufactured by Mitsubishi Kasei Co.) ・ Quaternary ammonium salt 2 parts (Orient Chemical Industry Co., Ltd.) Product name: P-51) Polypropylene 3 parts (Product name: Sanyo Kasei Kogyo Co., Ltd .: Viscole 330P)

The melting start temperature of the toner mother particles is 110.
° C. An electrophotographic toner for comparison was obtained in the same manner as in Example 1 except that the ultraviolet curable acrylate and the photoinitiator were not added to 100 parts by weight of the obtained toner mother particles (B).

Here, in evaluating the following characteristics of the toners of Examples 1 to 7 and Comparative Examples 1 and 2, hydrophobic silica TS-530 was used for 100 parts by weight of each toner.
(Cabot Corporation) 0.3 part by weight was added and the mixture was stirred and used. Evaluation of Blocking Property (1) A 150 cc bottle was filled with 20 g of the toner obtained in each of Examples 1 to 7 and Comparative Examples 1 and 2 and left in a constant temperature bath at 50 ° C. for 48 hours. The caking state of the toner was visually confirmed. The results are shown in Table 1.

[0034]

[Table 1]

Evaluation of Fixability, etc. (1) Further, 5 parts of the toner obtained in Examples 1 to 7 and Comparative Examples 1 and 2 and a ferrite carrier (trade name FL-1025 manufactured by Powder Tech Co., Ltd.). 95 parts were mixed to prepare a developer. The developer thus obtained was used in a copying machine (BD-2810 manufactured by Toshiba Corp.) to confirm the toner fixability and the image quality.

To fix the toner, the heat roller temperature of the copying machine was set to 130 ° C., the image density (A) of the image obtained by fixing the toner was measured, and then the image was rubbed with an eraser. After that, the obtained image density (B) is measured,
It was confirmed by the residual rate (%) according to the following formula.

Residual rate (%) = (B / A) × 100 The residual rate of this image density is a value measured by a Macbeth reflection densitometer (manufactured by Macbeth Co., Ltd., trade name: RD-914). Regarding the image quality, a continuous printing test of 5,000 sheets was performed using the above copying machine in an environment of 25 ° C. and 60% RH, and a white meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name; MODEL Z-100) was used.
1DP), and the copy image at the beginning of continuous printing and 5
It was confirmed by measuring the image density (ID) of the copied image after 000 sheets and the background stain (BG) of the non-image area. The results of these measurements are shown in Table 2.

[0038]

[Table 2] In Comparative Example 1, toner lumps were generated during development, image defects occurred, and in Comparative Example 2, the fixability was poor.

From the results shown in Tables 1 and 2, the toner according to the present embodiment is excellent in blocking resistance as compared with the conventional toner, although the melting start temperature is lower. It was confirmed. That is, since the electrophotographic toner according to the present embodiment is provided with the ultraviolet curable acrylate coating on the surface of the toner mother particles,
Even if the binder resin occupying most of the toner weight is softened by heat, the binder resins do not come into contact with each other.
It is possible to prevent blocking from occurring.

Further, even when pressure is applied to the electrophotographic toner of this embodiment from a sleeve or a blade,
Since the binder resin is covered with the ultraviolet-curable acrylate coating, it does not come into direct contact with these members. Therefore, according to the electrophotographic toner of this embodiment, the toner is unlikely to be fused to the sleeve or the blade.

Further, the melting start temperature of the entire electrophotographic toner of this embodiment could be controlled to 92 ° C. Since this temperature is considerably lower than the melting start temperature of the conventional toner of 110 ° C., the heat fixing device can be maintained at a temperature considerably lower than the conventional temperature. Therefore, the electrophotographic toner of this embodiment has excellent fixability even at low temperatures, so that the power consumption of the copying machine can be reduced.

Example 8 To 100 parts of the same toner mother particles (A) as in Example 1,
0.15 parts of electron beam curable amine-modified oligoetherether acrylate (manufactured by BASF, trade name: Laromer PO83F) was spray-added and stirred in a Henschel mixer to uniformly adhere the acrylate to the surface of the toner mother particles. Post-pressurization voltage of 200 V, beam current of 10 mA, 5 Mrad
The acrylate was cured by irradiating it with an electron beam for 3 minutes so that the absorbed dose was 1. The photopolymerization initiator used at this time was diphenyl disulfide, and the addition amount was 3% based on Laromer PO83F.

Example 9 To 100 parts of the toner mother particles (A), Laromer P was added.
The same operation as in Example 8 was performed except that 0.5 part of O83F was added by spraying.

Example 10 To 100 parts of the toner mother particles (A), Laromer P was added.
The same operation as in Example 8 was performed except that 2.0 parts of O83F was added by spraying.

Example 11 With respect to 100 parts of the toner mother particles (A), Laromer P was used.
The same operation as in Example 8 was carried out except that 5.0 parts of O83F was added by spraying.

Example 12 An electron beam curable acrylate (manufactured by San Nopco: trade name; Photomer 416) using isopropyl alcohol as a solvent for 100 parts of the toner mother particles (A).
0, photopolymerization initiator diphenyl disulfide 3%) 6.
The same operation as in Example 8 was carried out except that 0 part of the mixture was added by spraying and the mixture was stirred under pressure at a jacket temperature of 40 ° C. for 5 minutes before electron beam irradiation.

Example 13 The same operation as in Example 8 was carried out except that 0.5 part of electron beam curable acrylate PO83F was spray-added to 100 parts of the toner mother particles (A).

Example 14 The same operation as in Example 8 was performed, except that 8.0 parts of electron beam curable acrylate PO83F was spray-added to 100 parts of the toner mother particles (A).

Comparative Example 3 The same operation as in Example 8 was performed except that the electron beam curable acrylate PO83F and the photopolymerization initiator were not added to 100 parts of the toner mother particles (A), and an electrophotographic image for comparison was prepared. To obtain toner for use.

Comparative Example 4 The same operation as in Example 8 was conducted except that the electron beam curable acrylate and the photopolymerization initiator were not added to 100 parts by weight of the same toner mother particles (B) as in Comparative Example 2. To obtain a toner for electrophotography.

Here, in evaluating the following various characteristics of the toners of Examples 8 to 14 and Comparative Examples 3 to 4,
Hydrophobic silica TS-53 for 100 parts by weight of each toner
0 (Cabot) 0.3 part by weight was added, and the mixture was stirred and used. Evaluation of blocking property (2) A toner of 20 g obtained in each of Examples 8 to 14 and Comparative Examples 3 to 4 was filled in a 150 cc bottle and left in a constant temperature bath at 50 ° C. for 48 hours. The caking state of was confirmed visually. Table 3 shows the results.

[0052]

[Table 3]

Evaluation of Fixability, etc. (2) Further, Examples 8 to 14 and Comparative Examples 3 to 4 described above.
A developer was prepared by mixing 5 parts of the toner obtained in step 5 with 95 parts of a ferrite carrier (trade name FL-1025 manufactured by Powdertech Co., Ltd.). Using the obtained developer, the fixing property of the toner was evaluated by the same method as described above. The results are shown in Table 4 below.

[0054]

[Table 4]

In Comparative Example 3, toner lumps were generated in the image to cause image defects, and in Comparative Example 4, the fixability was poor.

From the results shown in Tables 3 and 4, the toner according to this embodiment is excellent in blocking resistance as compared with the conventional toner, although the melting start temperature is lower. It was confirmed. That is, in the electrophotographic toner according to the present embodiment, since the coating of the electron beam curable acrylate is provided on the surface of the toner mother particles,
Even if the binder resin occupying most of the toner weight is softened by heat, the binder resins do not come into contact with each other.
It is possible to prevent blocking from occurring.

Even when pressure is applied to the electrophotographic toner of this embodiment from a sleeve or a blade,
Since the binder resin is covered with the electron beam curable acrylate coating, it does not come into direct contact with these members. Therefore, according to the electrophotographic toner of this embodiment, the toner is unlikely to be fused to the sleeve or the blade.

Further, the melting start temperature of the entire electrophotographic toner of this example could be controlled to 92 ° C. Since this temperature is considerably lower than the melting start temperature of the conventional toner of 110 ° C., the heat fixing device can be maintained at a temperature considerably lower than the conventional temperature. Therefore, the electrophotographic toner of this embodiment has excellent fixability even at low temperatures, so that the power consumption of the copying machine can be reduced.

In the electrophotographic toner according to the present invention, the surface of the toner mother particles containing the binder resin and the colorant is coated with the electron beam curable acrylate, so that the toner occupying most of the toner weight. Even if the binder resin of the mother particles is softened by heat, the binder resins do not come into contact with each other, so that blocking can be prevented. Also in the manufacturing method, there is an advantage that an electron beam irradiation device is incorporated into an existing stirring device to cure in a short time.

Since the electrophotographic toner of the present invention can be considerably lower than the melting start temperature of the conventional toner of 110 ° C., the heat fixing device can be maintained at a temperature much lower than the conventional temperature. Therefore, according to the electrophotographic toner of the present invention, it is possible to reduce the power consumption of the electrophotographic copying machine and the printer.

[0061]

In the electrophotographic toner according to the present invention, the surface of the toner mother particles containing the binder resin and the colorant is coated with the ultraviolet curable or electron beam curable acrylate, and therefore the toner weight Even if the binder resin of the toner mother particles, which occupies most of the above, is softened by heat, the binder resins do not come into contact with each other, so that blocking can be prevented from occurring. Also in the manufacturing method, there is an advantage that curing can be performed in a short time in a simple process only by incorporating an ultraviolet irradiation device or an electron beam accelerator into an existing stirring device.

Since the electrophotographic toner of the present invention can be considerably lower than the melting start temperature of the conventional toner of 110 ° C., the heat fixing device can be maintained at a temperature much lower than the conventional temperature. Therefore, according to the electrophotographic toner of the present invention, it is possible to reduce the power consumption of the electrophotographic copying machine and the printer.

Claims (4)

[Claims] 1. An electrophotographic toner comprising a toner mother particle containing at least a binder resin and a colorant, and a surface of the toner mother particle coated with a cured film of an ultraviolet curable or electron beam curable acrylate. 2. The toner for electrophotography according to claim 1, wherein 100 parts by weight of the toner mother particles are coated with 0.1 part by weight or more and 5 parts by weight or less of an ultraviolet curable or electron beam curable acrylate. 3. The electrophotographic toner according to claim 1, wherein the melting start temperature is 60 ° C. or higher and 100 ° C. or lower. 4. An electrophotographic toner obtained by coating the surface of a toner mother particle containing at least a binder resin and a colorant with an ultraviolet curable or electron beam curable acrylate and irradiating it with ultraviolet rays or an electron beam to cure it. A method for producing an electrophotographic toner.