JP2932039B2 - Manufacturing method of 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 employing heat fixing.

[0002]

2. Description of the Related Art In recent years, in a copying machine and a printer using an electrophotographic system, a toner which can be fixed by a low-temperature fixing roll has been demanded in order to reduce power consumption. In response to this requirement, in the prior art, there has been proposed a binder resin having improved molecular weight and molecular weight distribution contained in the toner. Specifically, attempts have been made to lower the fixing temperature by lowering the molecular weight of the binder resin. 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 the low molecular weight region and the high molecular weight region of the molecular weight distribution of the binder resin, or crosslinking of a high molecular weight portion has been performed. However, in this method, the glass transition point of the resin must be lowered in order to have sufficient fixability at a low temperature, and there has been a problem that the blocking property of the toner is deteriorated. That is, blocking during storage of the toner at a high temperature, blocking of the toner on the carrier due to friction with the carrier in the developing device, blocking of the collected toner in the cleaning process, and the like are applicable. In particular, when applied to a non-magnetic one-component system, the toner is frictionally charged with a blade for forming a toner layer on a sleeve, and charging and layer formation are performed, so that stress such as heat or pressure is applied to the toner. In addition, since the toner itself does not have heat resistance and pressure resistance, there is a problem that the blocking of the toner to the sleeve or the blade 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 toner surface or a fine particle made of an organic material or an inorganic material is mechanically attached. However, with these methods, it is difficult to completely cover the surface of the toner particles with the material particles, and there have been problems such as deterioration of fixability and decrease in image density due to an increase in the added amount.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic toner which can be fixed at a low temperature by using a binder resin having a low softening point and does not cause blocking. And

[0004]

The process for producing an electrophotographic toner according to the present invention is characterized in that a mixture of at least one of diisocyanate or polyisocyanate and a polyhydric alcohol is melt-kneaded with at least a binder resin and a colorant. after dispersing on the surface of the toner mother particles containing, high-speed care
Flow impact method or dry mechanochemical method or in hot air flow
It is characterized by being cured by a modification method .
Further, the method for producing an electrophotographic toner according to the present invention,
After at least one diisocyanate or polyisocyanate, and dispersed on the surface of the toner mother particles containing by melt-kneading at least a binder resin and a colorant was further dispersed multivalent amine on the surface of the toner mother particles, high speed air flow
Medium impact method or dry mechanochemical method or hot air flow
It is characterized by being cured by a quality method .

Hereinafter, the present invention will be described in detail. To obtain the electrophotographic toner of the present invention, forming toner base particles,
It can be obtained by providing a cured film on its surface with at least one of diisocyanate or polyisocyanate and at least one of polyhydric alcohol or polyamine. That is, the toner base particles are mixed with a binder resin, a colorant, and if necessary, other additives such as a charge control agent, a release agent, and a magnetic substance at a desired mixing ratio, and are melt-kneaded. Next, the material solidified by cooling is pulverized and classified to have an average particle size of 5 to 20 μm . Subsequently, a cured film of at least one of diisocyanate or polyisocyanate and at least one of polyhydric alcohol or polyamine is provided on the surface of the obtained toner base particles to obtain the electrophotographic toner of the present invention. Further, a toner for electrophotography may be constituted by adding and mixing a fluidity improver composed of fine resin particles, hydrophobic silica, colloidal silica or the like to the particles having a cured film thus obtained.

Most of the toner base particles of the toner for electrophotography of the present invention are composed of a binder resin. Therefore, what kind of binder resin is used has a great influence on the melting start temperature of the toner. Affects low-temperature fixability. Polystyrene, styrene- (meth) acrylate copolymer, polyester, epoxy resin, etc. can be used as the binder resin used for the toner base particles. In order to enable the fixing property, it is preferable to use a resin having a molecular weight as small as possible. A resin having a low molecular weight has a lower melting onset temperature than a resin having a higher molecular weight, and a resin having a lower glass transition point (Tg) is also preferably used because it has a lower melting onset temperature than a resin having a high glass transition point. As the resin having a small molecular weight, a resin having a molecular weight peak position at 3000 to 8000 in a chromatogram measured by gel permeation chromatography (GPC) is preferable, and one or two or more molecular weight peak positions are present. It may be something. By selecting such a binder resin, the melting start temperature of the toner base particles can be controlled to 100 ° C. or lower, which is lower than the melting start temperature of the conventional toner, so that low-temperature fixing becomes possible. However, lowering the melting start temperature of the binder resin more than necessary, that is, for example, if the melting start temperature is lower than 60 ° C., the toner softens under a high-temperature and high-humidity environment.
Not preferred for storage stability. For this reason, 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 for the toner base particles is set to a temperature that is capable of fixing the toner to the paper at a low fixing roll temperature and that is preferable for storage stability, that is, 60 ° C. to 100 ° C. Is preferred. The melting start temperature specified in the present invention means the temperature at which the plunger starts to fall under the following measurement conditions. Measuring machine: Shimadzu 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

The styrene exemplified above as the binder resin
As the monomer of the acrylic component constituting the (meth) acrylate copolymer, for example, methyl acrylate,
Ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, acrylic acid Phenyl, α-
Methyl chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, methacrylate Examples thereof include 2-ethylhexyl acrylate, stearyl methacrylate, phenyl methacrylate, and dimethylaminoethyl methacrylate.

[0008] Colorants include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachide green oxalate, and the like. Can be mentioned.

As the charge control agent, a charge control agent conventionally used can be used. Examples thereof include nigrosine dyes, quaternary ammonium salts, triphenylmethane dyes, and monoazo metal complex dyes.

The diisocyanate applied to the electrophotographic toner of the present invention is 2,4-tolylene diisocyanate,
Examples thereof include 2,6-tolylene diisocyanate, hexamethylene diisocyanate, and 4,4-diphenylmethane diisocyanate. Further, a polyisocyanate obtained by cyclically or polymerizing these diisocyanates may be used. Specific examples of the polyisocyanate include a coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.), a trimer of hexamethylene diisocyanate, a Desmodur N3390 (manufactured by Sumitomo Bayer Urethane Co., Ltd.); and a Sumidur, a trimer of tolylene diisocyanate. FL
(Manufactured by Sumitomo Bayer Urethane Co.); Millionate MR obtained by polymerizing 4,4-diphenylmethane diisocyanate
-100 (manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like.

Examples of the polyhydric alcohol applied to the electrophotographic toner of the present invention include ethylene glycol,
1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, sorbitol,
1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, Glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3
5-trihydroxybenzene and the like.

Examples of the polyvalent amine applicable to the electrophotographic toner of the present invention include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, 2-hydroxy Trimethylenediamine,
Examples thereof include diethylenetriamine, triethylenetetraamine, diethylaminopropylamine, and tetraethylenepentamine.

The total amount of at least one of diisocyanate or polyisocyanate and at least one of polyhydric alcohol or polyamine added to the toner base particles is 0.01 to 10 parts by weight based on 100 parts by weight of the toner base particles.
Parts by weight, more preferably 0.03 to 5 parts by weight.
If the amount is less than 0.01 part by weight, the thickness of the coating film formed on the surface of the toner base particles becomes thin, and the coating effect is not exhibited. on the other hand,
If the amount is more than 10 parts by weight, the fixing property of the toner is lowered, and the curing of a large amount of the coating layer is troublesome and the production efficiency may be lowered, which is not preferable. In the present invention, diisocyanate and polyisocyanate can be used alone or in combination,
The polyhydric alcohol and the polyhydric amine can be used alone or in combination, respectively, and these can be used alone or in combination. By controlling the ratio of the diisocyanate and the polyisocyanate in combination as described above, the viscosity of the uncured coating dispersed on the surface of the toner base particles can be adjusted. By controlling the curing time, the curing time of the coating before the curing can be adjusted.

As a method of forming a cured film on the surface of the toner base particles by at least one of diisocyanate or polyisocyanate and at least one of polyhydric alcohol or polyamine, the following method can be exemplified. And the method, in the case of using the at least one preparative polyhydric alcohols di- or polyisocyanates, the toner base particles unnatural death E Rumikisa (manufactured by Mitsui Mitsuikekogyo Co.) or a super mixer (Kawada Seisakusho) high-speed stirrer such as After that, a mixture of at least one of diisocyanate or polyisocyanate and a polyhydric alcohol is added and uniformly stirred and dispersed. Then, the mixture is treated with an apparatus having higher stirring and mixing power to raise the surface temperature and harden. In addition, such a dispersion and curing treatment may be continuously performed at once. Further, a method of curing is using high production efficiency is high the mixing power device. In the case of using the at least one preparative polyvalent amine of di- or polyisocyanates and placed toner base particles unnatural death E Rumikisa (manufactured by Mitsui Mitsuikekogyo Co.) or a super mixer (manufactured by Kawata Seisakusho Co.) high-speed stirrer such as Thereafter, at least one of diisocyanate and polyisocyanate is added and stirred and dispersed, and then a polyvalent amine is added and uniformly stirred and dispersed. Then, the mixture is treated with an apparatus having higher stirring and mixing power to raise the surface temperature and harden. In addition, such a dispersion and curing treatment may be continuously performed at once. Further, a method of curing is using high production efficiency is high the mixing power device. As a method of curing the coating, a hybridization system (manufactured by Nara Machinery Co., Ltd.) which applies the high speed air stream impact method, (manufactured by Kawasaki Heavy Industries) COSMOSYSTEM, mechanofusion system (manufactured by Hosokawa Micron Co., Ltd. was applied dry mechanochemical method ), A mechanomill (manufactured by Okada Seiko Co., Ltd.), a surf fusing system (manufactured by Nippon Pneumatic Industries Co., Ltd.) using a hot air reforming method, and the like .

The toner for electrophotography of the present invention may be used as a two-component developer by being mixed with a carrier composed of iron powder, ferrite, granulated magnetite, or the like, or may be used as a non-magnetic one-component developer. Is also good. Further, it may be used as a magnetic one-component developer as it is without mixing with a carrier and containing a magnetic material, or may be mixed with a carrier and used for developing an electrostatic image.

[0016]

The toner for electrophotography of the present invention is obtained by curing at least one of diisocyanate and polyisocyanate and at least one of polyhydric alcohol and polyamine on the surface of toner base particles containing a binder resin and a colorant. Since the toner is provided with a coating, blocking does not occur even if the toner is placed in an environment higher than the glass transition temperature of the binder resin. Further, since the electrophotographic toner of the present invention can use a binder resin having a low melting start temperature, the fixing temperature can be considerably lower than that of the conventional electrophotographic toner. When at least one of diisocyanate or polyisocyanate is contacted with at least one of polyhydric alcohol and polyamine,
Since the curing reaction speed is higher than that of the conventional resin, it cures in a short time at the time of curing and coating on the surface of the toner base particles, so that workability and productivity are excellent.

[0017]

The present invention will be described below in more detail with reference to examples. In the examples, “parts” means “parts by weight”. (Example 1) In this example, first, toner base particles having the following composition were prepared.・ Styrene-acrylate copolymer resin 100 parts (monomer composition; styrene / butyl acrylate) High molecular weight compound Mw = 3.0 × 10 ⁶ , Mn = 1.0 × 10 ⁶ Low molecular weight compound Mw = 8.0 × 10 ³ , Mn = 2.7 × 10 ³ Low molecular weight: High molecular weight = 90: 10 Peak position of molecular weight by GPC: 5.2 × 10 ³ and 2.3 × 10 ⁶ · carbon black 6.5 parts ( (Mitsubishi Kasei Kogyo Co., Ltd .; MA-100)-Quaternary ammonium salt 2 parts (Orient Chemical Co., Ltd .; P-51)-Polypropylene 3 parts (Sanyo Chemical Co., Ltd., Viscol 330P) Toner In preparing the base particles, the raw materials having the above composition were mixed by a super mixer, melt-kneaded, and pulverized and classified to obtain positively chargeable toner base particles having an average particle diameter of 11 μm. The melting start temperature of the obtained toner base particles is 95.
° C. Next, to 200 g (1 equivalent) of a trimer of hexamethylene diisocyanate (Coronate HX purity: 84%, manufactured by Nippon Polyurethane Industry Co., Ltd.), 31 g (1 equivalent) of ethylene glycol (special grade reagent) was added and stirred to obtain a mixture A. . Next, 0.01 part of the mixture A was added to 100 parts of the obtained toner base particles, and the mixture was stirred in a Henschel mixer to uniformly disperse the mixture A on the surface of the toner base particles. Thereafter, the dispersed material is put into a hybridization system NHS-1 type (manufactured by Nara Machinery Co., Ltd.) and treated at a peripheral speed of about 80 m / sec at the tip of the blade for 10 minutes to cure the toner surface, and the toner for electrophotography according to the present invention. I got

Example 2 The addition amount of the mixture A was 0.05
The same operation as in Example 1 was carried out, except that the toner was used as a part to obtain an electrophotographic toner of the present invention.

Example 3 An electrophotographic toner of the present invention was obtained in the same manner as in Example 1, except that the amount of the mixture A was changed to 0.5 part.

Example 4 An electrophotographic toner of the present invention was obtained by performing the same operation as in Example 1 except that the amount of the mixture A was changed to 1.0 part.

Example 5 An electrophotographic toner of the present invention was obtained in the same manner as in Example 1, except that the amount of the mixture A was changed to 5.0 parts.

(Example 6) Toner base particles 10 of Example 1
To 0 part, 1.0 part of a trimer of hexamethylene diisocyanate (Coronate HX purity: 84%, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added, and the mixture was stirred in a Henschel mixer to be uniformly dispersed on the surface of the toner base particles. Was. Next, 0.2 parts of diethylenetriamine (special reagent grade) was added,
The mixture was stirred in a Henschel mixer and uniformly dispersed on the surface of the toner base particles in the same manner as described above. Thereafter, the dispersed material is charged into a hybridization system NHS-1 (Nara Machinery Co., Ltd.), and the peripheral speed of the blade tip is about 80 m /
This was treated for 10 minutes for 10 seconds to cure the toner surface to obtain the electrophotographic toner of the present invention.

(Example 7) To 84 g (1 equivalent) of hexamethylene diisocyanate (special grade of reagent), 31 g (1 equivalent) of ethylene glycol (special grade of reagent) was added and stirred.
A mixture B was obtained. Next, 1.0 part of the mixture B was added to 100 parts of the toner base particles of Example 1, and the mixture was stirred in a Henschel mixer to uniformly disperse the mixture B on the surface of the toner base particles. Thereafter, the dispersed material is put into a hybridization system NHS-1 (Nara Machinery Co., Ltd.), and the material is dispersed at a peripheral speed of about 80 m / sec at the tip of the blade.
After treating for 0 minutes, the toner surface was cured to obtain the electrophotographic toner of the present invention.

(Embodiment 8) Toner base particles 10 of Embodiment 1
To 0 part, 0.8 part of hexamethylene diisocyanate (special grade of reagent) was added, and the mixture was stirred in a Henschel mixer to be uniformly dispersed on the surface of the toner base particles. Next, 0.2 parts of diethylenetriamine (special grade of reagent) was added, and the mixture was stirred in a Henschel mixer to be uniformly dispersed on the surface of the toner base particles in the same manner as described above. After that, the dispersed material is put into a hybridization system NHS-1 (Nara Machinery Co., Ltd.), and the peripheral speed of the tip of the blade is about 80 m / s.
ec for 10 minutes to cure the toner surface to obtain the electrophotographic toner of the present invention.

Example 9 For 200 g (1 equivalent) of a trimer of hexamethylene diisocyanate (Coronate HX purity: 84%, manufactured by Nippon Polyurethane Industry Co., Ltd.), 42 g (0.5 g of special grade of hexamethylene diisocyanate) was used.
Was added and mixed, and 47 g (1.5 equivalents) of ethylene glycol (special reagent grade) was further added and stirred to obtain a mixture C. Next, with respect to 100 parts of the toner base particles of Example 1,
1.0 part of the mixture C was added and stirred in a Henschel mixer to uniformly disperse the mixture C on the surface of the toner base particles. Then the hybridization system NHS
The dispersed material was put into a -1 type (manufactured by Nara Machinery Co., Ltd.) and treated at a peripheral speed of about 80 m / sec at the tip of the blade for 10 minutes to cure the toner surface to obtain the electrophotographic toner of the present invention.

Example 10 155 g (5 equivalents) of ethylene glycol (reagent special grade) was added to 26 g (1 equivalent) of diethylenetriamine (special grade reagent) and stirred to obtain a mixture D. Next, 1.0 part of a trimer of hexamethylene diisocyanate (Coronate HX purity: 84%, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to 100 parts of the toner base particles of Example 1, and the mixture was stirred in a Henschel mixer. It was uniformly dispersed on the surface of the toner base particles. Next, 0.15 parts of the mixture D was added, and the mixture was stirred in a Henschel mixer.
Similarly, the particles were uniformly dispersed on the surface of the toner base particles. Thereafter, the dispersed material is put into a hybridization system NHS-1 type (manufactured by Nara Machinery Co., Ltd.) and treated at a peripheral speed of about 80 m / sec at the tip of the blade for 10 minutes to cure the toner surface, and the toner for electrophotography according to the present invention. I got

Comparative Example 1 An electrophotographic toner for comparison was obtained in the same manner as in Example 1 except that the mixture A was not added.

Comparative Example 2 To 200 g (1 equivalent) of a trimer of hexamethylene diisocyanate (Coronate HX manufactured by Nippon Polyurethane Industry Co., Ltd.), 46 g (1 equivalent) of ethanol (special grade reagent) was added, and the mixture was stirred. Obtained.
Next, a comparative electrophotographic toner was obtained by performing the same operation as in Example 1 except that 1.0 part of mixture E was added instead of mixture A.

Comparative Example 3 To 99 g (1 equivalent) of isobutyl isocyanate (special grade of reagent), 31 g (1 equivalent) of ethylene glycol (special grade of reagent) was added and stirred to obtain a mixture F. Next, mixture F was replaced with mixture F for 1.0 hour.
An electrophotographic toner for comparison was obtained by performing the same operation as in Example 1 except that the above-mentioned parts were added.

Here, Examples 1 to 10 and Comparative Examples 1 to 3
Each of the toners was evaluated by adding 0.3 parts by weight of hydrophobic silica (manufactured by Cabot Corporation, TS-530) to 100 parts by weight of each electrophotographic toner, and externally adding the resulting mixture using a Henschel mixer. Was used.

Next, the following items were tested for the above-mentioned Examples and Comparative Examples. (1) Blocking Property The blocking properties of the electrophotographic toners obtained in Examples 1 to 10 and Comparative Examples 1 to 3 after the external addition treatment were evaluated. The evaluation of the blocking property was performed by filling 20 g of the obtained electrophotographic toner in a 150 cc bottle,
After standing in the constant temperature bath for 48 hours, the caking state of the toner for electrophotography was visually confirmed. (2) Fixability 5 parts of each of the electrophotographic toners obtained in Examples 1 to 10 and Comparative Examples 1 to 3 were mixed with 95 parts of a ferrite carrier (product name: FL-1025, manufactured by Powder Tech) and developed. An agent was prepared. The obtained developer is used in a copying machine (BD manufactured by Toshiba Corporation).
-2810) to confirm the fixability of the toner. The fixing property of the toner is determined by setting the heat roller temperature of the above copying machine to 1
The image density (A) of the solid image obtained by fixing the toner at 30 ° C. was measured, and then the image was rubbed with an eraser. Then, the obtained image density (B) was measured. The fixability (%) was determined by the following formula. Fixability (%) = (B / A) × 100 The image density is a value measured by a Macbeth reflection densitometer (trade name: RD-914, manufactured by Macbeth). (3) Image characteristics The image characteristics were determined by performing a continuous print test of 5000 sheets using the developer and the copying machine described in the above item (2) in an environment of 25 ° C. and 60% RH. This was confirmed by measuring the image density of the copy image at the initial stage of continuous printing and the copy image after 5,000 sheets, and the background stain of the non-image area, using an industrial company (trade name: Model Z-1001DP). The results of these measurements are shown in Table 1 below. In addition, in Comparative Examples 1 to 3, since a lump of toner was generated during the test of the blocking property, the tests of the fixing property and the image characteristics were not performed.

[0032]

[Table 1]

From the results shown in Table 1, the electrophotographic toners according to Examples 1 to 10 have lower melting start temperatures than the conventional toners.
It was confirmed that the blocking resistance was excellent. That is, since the electrophotographic toner of the present invention has a cured film of at least one of diisocyanate or polyisocyanate and at least one of polyhydric alcohol or polyamine on the surface of the toner base particles, even if the toner weight is large. Even if the binder resin occupying the portion is softened by heat, the binder resins do not come into contact with each other, so that it was confirmed that blocking was prevented from occurring. Also,
The temperature of the electrophotographic toner of Examples 1 to 10 was 130 ° C.
Even at such a low temperature, it was confirmed that the toner had sufficient fixing strength to transfer paper for practical use. In addition, it was confirmed that the electrophotographic toners of Examples 1 to 10 had sufficient image density and a level of background contamination which had no practical problem until 5000 sheets. Further, in Examples 1 to 10, it was confirmed that the toner for electrophotography was not fused to the sleeve or blade of the copying machine for applying pressure to the toner for electrophotography.

[0034]

The toner for electrophotography of the present invention has no problem in the blocking property and can be fixed at a low temperature.
In addition, there is an effect that the fixing strength is excellent and a sufficient number of image densities can be obtained. Therefore,
When the electrophotographic toner of the present invention is applied to a copying machine, a printer, or the like, power consumption can be reduced, and effects such as an increase in copying speed can be achieved.

Claims (2)

(57) [Claims] 1. A mixture of at least one of a diisocyanate or a polyisocyanate and a polyhydric alcohol,
After at least a binder resin and a colorant is dispersed on the surface of the toner base particles containing the melt-kneading, a high speed air stream impact
Method or dry mechanochemical method or hot air reforming method
A method for producing an electrophotographic toner, which is further cured. 2. Dispersing at least one of diisocyanate and polyisocyanate on the surface of toner base particles containing at least a binder resin and a colorant by melt-kneading, and further dispersing a polyvalent amine on the surface of the toner base particles. After that, impact method in high-speed airflow or dry mechanochemical method
Alternatively, a method for producing an electrophotographic toner, wherein the method is cured by a hot air current reforming method.