JPH08129271A - Electrophotographic toner and its production - Google Patents

Abstract

PURPOSE: To obtain an electrophotographic toner not causing blocking and having a long service life as a toner using a bonding resin having a low softening point and fixable at a low temp. by forming a cured coating film consisting of a resin having epoxy groups and an epoxy resin curing agent on the surface of each of toner matrix particles. CONSTITUTION: A cured coating film consisting of a resin having epoxy groups and an epoxy resin curing agent is formed on the surface of each of toner matrix particles contg. a bonding resin made essentially of a resin having epoxy groups, an epoxy resin curing agent and a colorant to obtain the objective electrophotographic toner. In this toner, the bonding resin may be made of only the resin having epoxy groups or may be made of a mixture of the resin having epoxy groups with other bonding resin. When the mixture is used, the blending ratio is not limited. The toner matrix particles further contain an electric charge controlling agent and other additives.

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 printer which employs heat fixing.

[0002]

2. Description of the Related Art Recently, electrophotographic copying machines and printers are required to be fixed at a low temperature in order to reduce power consumption. In the prior art to meet this requirement,
Proposals have been made for binder resins having improved molecular weight and molecular weight distribution. Specifically, attempts have been made to lower the fixing temperature by lowering the molecular weight of the binder resin.
However, when the molecular weight is lowered, the melting point is lowered, but at the same time, the melt viscosity is also lowered, so that there is a problem that an offset phenomenon occurs on the fixing roll. In order to prevent this offset phenomenon, a method of widening the low molecular weight region and the high molecular weight region of the molecular weight distribution of the binder resin, or cross-linking of the polymer portion has been performed.

However, in this method, the glass transition point of the resin is unavoidably lowered in order to provide sufficient fixing property, which causes a problem that the blocking property of the toner is deteriorated. That is, blocking occurs due to storage of toner at high temperature, blocking of toner onto the carrier due to friction with the carrier in the developing device, blocking of recovered toner during the cleaning process, and the like. Moreover, especially in the case of the non-magnetic one-component developing system,
A toner for forming a toner layer on the sleeve rubs the toner to charge and form a layer, so that stress such as heat or pressure is applied to the toner. With a conventional toner having a low glass transition temperature, the sleeve and the blade are used. However, there is a drawback that the blocking property occurs and the developability is greatly impaired.

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 fine particles made of an organic material or an inorganic material are mechanically attached. However, with these methods, it is difficult to completely cover the surface of the toner with the material particles, and there is a possibility that the fixing property may be deteriorated and the image density may be decreased with an increase in the amount of the material particles added.

[0005]

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. The purpose is to

[0006]

The toner for electrophotography according to the present invention has a surface of a toner mother particle containing a binder resin at least composed of a resin containing an epoxy group, an epoxy resin curing agent and a colorant. A toner for electrophotography, characterized in that a cured coating of the epoxy group-containing resin and an epoxy resin curing agent is provided on the. Further, the electrophotographic toner of the present invention applies heat treatment or mechanical impact to toner mother particles containing a binder resin composed of at least an epoxy group-containing resin, an epoxy resin curing agent, and a colorant. As a result, the toner base particles can be manufactured by providing a cured coating of the epoxy group-containing resin and the epoxy resin curing agent on the surface of the toner mother particles.

Hereinafter, the present invention will be described in detail. Most of the toner base particles of the electrophotographic toner of the present invention are composed of a binder resin, like the conventional toner. Therefore, what kind of binder resin is used depends on the melting start temperature of the toner. Have a big impact. The electrophotographic toner of the present invention may comprise a binder resin only with a resin having an epoxy group, or a mixture of a resin having an epoxy group and a conventionally known binder resin. Good. When a mixture of a resin having an epoxy group and a conventionally known binder resin is used, the compounding ratio is not limited.

As a resin having an epoxy group used as a binder resin for the electrophotographic toner of the present invention, a bisphenol A type epoxy resin produced by a condensation reaction of bisphenol A and epichlorohydrin is generally used. Trade name of the company; Epotote YD-013
Various grades such as YD-014 and YD-017 are used in the present invention, but other types of epoxy resins can also be used as appropriate. Further, an acrylic resin having an epoxy group such as a graft polymer of ethylene glycidyl methacrylate copolymer and vinyl polymer may be used as the binder resin. Specific examples of the graft polymer of ethylene glycidyl methacrylate copolymer and vinyl polymer are trade names of NOF CORPORATION; MODIPER A4100.
(Ethylene glycidyl methacrylate copolymer / polystyrene graft polymer composition ratio 70/30), trade name: MODIPER A4200 (ethylene glycidyl methacrylate copolymer / polymethyl methacrylate graft polymer composition ratio 70/30), trade name MODIPER A4400 (graft polymer of ethylene glycidyl methacrylate copolymer and acrylonitrile-styrene copolymer, composition ratio 70/30) and the like.
Examples of the binder resin used together with the resin having an epoxy group include polyester, polystyrene, and styrene-methacrylic acid ester copolymer. In the present invention, 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.

Examples of the diol component of the polyester resin used as the binder resin in combination with the resin having an epoxy group in the present invention include ethylene glycol and 1,2-
Propylene glycol, 1,3-propylene glycol, 1,4-butane diol, neopentyl glycol, 1,4-butene diol, 1,5-pentane diol, 1,6-hexane diol, or polyhydric alcohol having a valence of 3 or more. Examples of sorbitol, 1, 2,
3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol,
1,2,5-Pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxybenzene Etc. As the acid component,
Fumaric acid, maleic acid, phthalic acid, isophthalic acid, itaconic acid, glutaconic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid,
Malonic acid, alkenylsuccinic acid, 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene Carboxypropane, tetra (methylenecarboxyl) methane, 1,
2,7,8-octane tetracarboxylic acid etc. are mentioned.

Examples of the epoxy resin curing agent applied to the electrophotographic toner of the present invention include aromatic amines such as m-phenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone, trimellitic anhydride, pyromellitic anhydride, and benzophenone anhydride. Tetracarboxylic acid,
Acid anhydrides such as reaction products of trimellitic anhydride and glycols, dicyandiamide, substituted dicyandiamides represented by 2,6-xylenyl-biguanide, dihydrazides such as adipic acid dihydrazide, sebacic acid dihydrazide, and isophthalic acid dihydrazide, BF ₃ Examples include boron trifluoride complex compounds such as monoethylamine complex, phenolic resins, and high acid value polyesters.

Examples of the colorant used in the mother particles of the electrophotographic toner of the present invention include carbon black, nigrosine dye, aniline blue, chalco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow and methylene blue. Mention may be made of chloride, phthalocyanine blue, malachide green oxalate, lamp black, rose bengal, mixtures thereof and the like. It is necessary that these colorants be contained in a sufficient ratio so that a visible image having a sufficient concentration is formed, and the ratio of the colorant is usually about 1 to 20 parts by weight with respect to 100 parts by weight of the binder resin. It is said that If it is less than 1 part by weight, coloring is insufficient, and if it exceeds 20 parts by weight, a coloring agent which is not effective for coloring is contained.

The toner mother particles constituting the electrophotographic toner of the present invention contain a colorant in addition to the above binder resin and epoxy resin curing agent, and further contain a charge control agent and other additives as required. To be done. As the charge control agent, conventionally used charge control agents can be used. Examples thereof include nigrosine-based dyes, quaternary ammonium salts, triphenylmethane-based and monoazo-based metal complex dyes.

In order to cause a curing reaction at a lower temperature in the toner mother particles of the present invention, a curing accelerator is added to the surface (that is, adhered to the surface of the toner mother particles) before heat treatment or mechanical impact. You can Examples of curing accelerators are resorcinol, diethylenetriamine, triethylenetetramine, diethanolamine, triethanolamine, α-aminophenol, p-aminophenol, tetraethylammonium hydroxide, formic acid, acetic acid, butyric acid, lactic acid, oxalic acid dihydrate. Substance, benzoic acid, salicylic acid, p-toluenesulfonic acid, acetamide, salicylamide, benzenesulfonamide, RSnX ₃ (R:
Alkyl group of C ₁ ~ _18, X; halogen) can be exemplified organic metal compounds such as.

Other additives that may be added as needed include a fluidizing agent. Examples of the fluidizing agent include conventionally known resin fine particles, hydrophobic silica, colloidal silica and the like.

In the present invention, by selecting a resin having an epoxy group or a mixture of this and an ordinary binder resin as the binder resin to be used, the melting start temperature of the toner mother particles can be set at the conventional melting start temperature. Lower than a certain 110 ℃,
More specifically, it can be controlled to 100 ° C. or lower.
However, if the melting start temperature of the binder resin is lowered more than necessary, 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.

In order to produce the electrophotographic toner of the present invention, a binder resin composed of at least an epoxy group-containing resin or, if necessary, other binder resin is used in combination. It is obtained by mixing an epoxy resin curing agent and a pigment to form toner mother particles, and then selectively curing only the surfaces of the mother particles by a curing reaction between the epoxy group-containing resin and the epoxy resin curing agent. That is, a binder resin containing at least a resin having an epoxy group, an epoxy resin curing agent, a colorant, a charge control agent and, if necessary, other additives are mixed at a desired mixing ratio and melt-kneaded. Then, by cooling, the solidified product is pulverized and classified to obtain toner mother particles. Also,
It is also possible to use a polymerizable resin as the binder resin other than the resin having an epoxy group and mix the above materials at the time of the 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 polymerization toner. Then, the obtained toner mother particles are provided with the means described below to form a coating film obtained by curing a resin having an epoxy group present on the surface of the toner mother particles to obtain the electrophotographic toner of the present invention.

As a method of selectively forming a cured coating film of an epoxy group-containing resin on the surface of toner mother particles, the following method can be exemplified. That is, in order to cure the epoxy resin and the epoxy resin curing agent, heat treatment or mechanical impact force is required for the toner mother particles. As the heat treatment means, mixers that give high-speed shearing force, such as a super mixer, a Henschel mixer, and a turbulizer, can be used. By stirring with these mixers, frictional heat is generated on the surface of the toner mother particles, and the reaction proceeds. When it is desired to further accelerate the reaction, means such as heating hot water through the jacket of the mixer or blowing hot air may be used together. Also, a surfing system (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) applying a reforming method in hot air, a batch type fluidized bed heat treatment machine (manufactured by Okawara Seisakusho Co., Ltd.) or the like may be used. On the other hand, various devices may be used as a method for applying a mechanical impact force to the mixture. For example, a hybridization system (manufactured by Nara Machinery Co., Ltd.) that applies the high-speed air impact method, a Cosmo system (manufactured by Kawasaki Heavy Industries, Ltd.), a mechanofusion system (manufactured by Hosokawa Micron) that applies the dry mechanochemical method, a mechanomill (Okada Seiko Co., Ltd.) Device) is used.

The toner for electrophotography of the present invention comprises a binder resin composed of at least a resin having an epoxy resin as described above, an epoxy resin curing agent and a colorant, and other toner components such as a charge control agent and a release agent. , Particles having a cured coating of the epoxy group-containing resin and the epoxy resin curing agent on the surface of the toner mother particles obtained by appropriately dispersing and containing a magnetic material and the like, and the average particle diameter thereof is in the range of 5 to 20 μm. Further, the electrophotographic toner of the present invention may be constituted by adding and mixing a fluidity improver made of fine silica powder or the like to the particles thus obtained.

The electrophotographic toner of the present invention is mixed with a carrier composed of iron powder, ferrite, granulated magnetite or the like to form a two-component developer, or a magnetic or non-magnetic single component without mixing with a carrier. It may be used as a developer.

The electrophotographic toner of the present invention comprises a binder resin composed of at least an epoxy group-containing resin, an epoxy resin curing agent and a colorant, and the epoxy group-containing resin on the surface of the toner mother particles. Since the toner is characterized by providing a cured coating with an epoxy resin curing agent, blocking may occur 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. And the fixing temperature of the toner is considerably lower than that of the conventional toner.

[0021]

EXAMPLES "Parts" in the following examples means "parts by weight". Further, the melting start temperature means the falling start temperature of the plunger under the measurement conditions shown below. Measuring machine: Shimadzu's advanced flow tester CFT-
500 Measurement conditions: Plunger 1cm ² Die diameter 1mm Die length 1mm Load 20kgF Preheating temperature 50 ~ 80 ° C Preheating time 300sec Heating rate 6 ° C / min

Example 1 In this example, first, toner mother particles having the following composition were prepared. Cross-linked polyester resin 100 parts (monomer composition; fumaric acid / terephthalic acid / trimellitic acid / propylene oxide-modified bisphenol A) Molecular weight distribution Mw = 1.0 × 10 ⁵ Mn = 3.5 × 10 ³ Epoxy resin 30 parts (Toto Kasei Co., Ltd. trade name; YD-014) ・ Substituted dicyandiamide 5 parts (Ciba-Geigy Co. trade name; HT2844) ・ Carbon black 6.5 parts (Mitsubishi Kasei Co. trade name; MA-100) ・ Fourth Grade ammonium salt 2 parts (Orient Chemical Co., Ltd. trade name; P-51) Polyethylene 3 parts (Hoechst brand name: PE-130)

To prepare the toner mother particles, the raw materials having the above composition are mixed with a super mixer, melt-kneaded, and then ground and classified to obtain positively-chargeable toner mother particles (A) having an average particle diameter of 11 μm. It was The melting start temperature of the obtained toner mother particles (A) is 87 ° C. The obtained toner mother particles (A) are mixed with the hybridization system NH.
The toner was put into an S-1 type (manufactured by Nara Machinery Co., Ltd.) and treated at a peripheral speed of the blade tip of about 80 m / sec for 10 minutes to harden the toner surface to produce an electrophotographic toner.

Example 2 An electrophotographic toner was manufactured in the same manner as in Example 1 except that the toner mother particles (A) obtained in Example 1 were used and the treatment time was 30 minutes.

Example 3 To 100 parts of the toner mother particles (A) obtained in Example 1, 0.5 part of diethylenetriamine (special grade reagent) was added and stirred in a Henschel mixer to obtain toner mother particle surfaces. After being uniformly adhered to the toner, the same operation as in Example 1 was performed to produce an electrophotographic toner.

Example 4 The toner mother particles (A) obtained in Example 1 were charged into a batch type fluidized bed heat treatment machine (manufactured by Okawara Seisakusho) and the air velocity was 0.33.
The toner for electrophotography was manufactured by processing at m / sec for 15 minutes at a processing temperature of 60 ° C.

Comparative Example 1 Comparative positively charging toner mother particles (B) were prepared in the same manner as in Example 1 except that the substituted dicyandiamide used in Example 1 was not used. The melting start temperature of the toner mother particles (B) is 86 ° C. The same operation as in Example 1 was performed except that the obtained comparative toner mother particles (B) were used. Comparative Example 2 The toner mother particles (A) of the examples were evaluated as they were without applying heat treatment and mechanical impact force.

Comparative Example 3 A composition composed of the following raw materials was mixed in a super mixer, melt-kneaded, pulverized and classified to have an average particle diameter of 11 μm.
To obtain positively chargeable toner mother particles (C). -Crosslinked polyester resin 100 parts (manufactured by Japan Carbide Co .; trade name NCP-33B, Mw = 1.5x10 ⁵ , Mn = 6.5x10 ³ ) -Carbon black 6.5 parts (product of Mitsubishi Kasei Co., Ltd. Name; MA-100) ・ Quaternary ammonium salt 2 parts (trade name: P-51 manufactured by Orient Chemical Industry Co., Ltd.) ・ Polyethylene 3 parts (trade name: PE-130 manufactured by Hoechst) Melting of toner mother particles (C) The starting temperature was 112 ° C. The obtained toner mother particles (C) were evaluated as a comparative electrophotographic toner without heat treatment and mechanical impact.

The electrophotographic toners of Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated for blocking property, fixing property and image characteristics. As a sample, hydrophobic silica (manufactured by Hoechst Co., H
(-2050 EP) was added to 0.3 part by weight and post-treated.

(1) Blocking property The blocking property was evaluated by filling 20 g of the obtained toner in a 150 cc bottle and leaving it in a constant temperature bath at 50 ° C. for 48 hours, and visually confirming the caking state of the toner. did. (2) Fixability 5 parts of the toners obtained in Examples 1 to 4 and Comparative Examples 1 and 2,
Ferrite carrier (Product name FL manufactured by Powder Tech Co., Ltd.
-100) 95 parts were mixed to prepare a developer. The resulting developer was used in a copying machine (BD-2810 manufactured by Toshiba Corp.) to confirm the fixing property of the toner. Toner fixability is measured by setting the heat roller temperature of the above copying machine to 130 ° C.
The image density (A) of the image obtained by fixing the toner is measured, then the image is rubbed with an eraser, and then the obtained image density (B) is measured, and confirmed by the residual ratio (%) according to the following formula. did. Residual rate (%) = (B / A) × 100 The residual rate of this image density is a value measured by a Macbeth reflection densitometer (manufactured by Macbeth, trade name: RD-914). (3) Image characteristics Image characteristics were measured by a Macbeth reflection densitometer (the above ) And a white meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name; MODEL Z-
It was confirmed by measuring image densities (ID) of copy images at the initial stage of continuous printing and copy images after 5,000 sheets and background stains (BG) of non-image areas by using 1001DP). The results of these measurements are shown in Table 1. In Comparative Examples 1 and 2, the toner was agglomerated during the blocking test, and therefore the fixing property and the image property were not tested.

[0031]

[Table 1]

From the results shown in Table 1 above, it is confirmed that the electrophotographic toners of Examples 1 to 4 simultaneously satisfy both the blocking property and the fixing property as compared with the conventional toners. Was done. That is, since the electrophotographic toner of the present invention is provided with a cured coating of an epoxy resin on the surface of toner mother particles, even if the binder resin occupying most of the toner weight is softened by heat, the binder resins are It has been confirmed that since it does not come into contact, blocking is prevented from occurring. It was also confirmed that the electrophotographic toners of Examples 1 to 4 had practically sufficient fixing strength on the transfer paper even at a low temperature of 130 ° C. Further, it was confirmed that the electrophotographic toners of Examples 1 to 4 had a sufficient image density and a degree of background staining which is not a practical problem after 5,000 sheets. Furthermore, in Examples 1 to 4, it was confirmed that the electrophotographic toner was not fused to the sleeve or blade of the copying machine that applies pressure to the electrophotographic toner.

[0033]

The electrophotographic toner of the present invention has no problem in blocking property and can be fixed at a low temperature.
In addition, the fixing strength is excellent and a sufficient number of sheets of image density can be obtained. Therefore,
When the electrophotographic toner of the present invention is applied to a copying machine, a printer, or the like, it is possible to reduce power consumption and to achieve an effect such as a higher copying speed.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location 372 381

Claims (4)

[Claims] 1. A surface of a toner mother particle containing a binder resin at least composed of a resin containing an epoxy group, an epoxy resin curing agent and a colorant is cured with the epoxy group containing resin and the epoxy resin curing agent. An electrophotographic toner having a coating film. 2. The melting start temperature of the toner is 60 ° C. or higher and 100.
The toner for electrophotography according to claim 1, which has a temperature of not higher than ° C. 3. A toner mother particle containing a binder resin at least composed of a resin containing an epoxy group, an epoxy resin curing agent, and a colorant is subjected to heat treatment or mechanical impact to give the toner mother particle. A method for producing an electrophotographic toner, which comprises providing a cured coating of the epoxy group-containing resin and an epoxy resin curing agent on the surface of particles. 4. The method for producing an electrophotographic toner according to claim 3, wherein amines are added to the surface of the toner mother particle before the heat treatment or the mechanical impact force is applied.