JP3359654B2 - Manufacturing method of toner for electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner containing an inorganic additive used for developing an electrostatic image in electrophotography, electrostatic printing and the like.

[0002]

2. Description of the Related Art In the case of a dry method, an electrostatic image formed by an electrophotographic method, an electrostatic printing method, or the like is generally developed on a dry toner containing a binder resin and a colorant as main components, and then on a copy paper. Is transferred and fixed. To form a good image by this method, the toner particles have a high triboelectric charging ability,
In addition, it must have high fluidity. In order to cope with such a demand, conventionally, an inorganic additive or the like has been added as an external additive.

[0003] For example, as disclosed in JP-A-51-120631, JP-A-48-47346, JP-A-46-5782, and JP-A-51-101535, silicon, titanium, aluminum or the like is disclosed. In recent years, there has been a demand for higher image quality and the toner particle size has been decreasing, and furthermore, toners used for low-temperature fixing and high-speed copying have been developed. Toner using low softening point resin or wax
Then, due to the tackiness of the resin, the smaller the particle size, the more insufficient the fluidity, and an additive that further improves the fluidity is desired. Furthermore, as a method for solving this, a method of mixing and using two kinds of additives having different properties has been devised. For example, JP-A-60-1367
In JP-A-55-55, silica and titanium oxide are mixed.
In JP 1872, additives having different particle sizes are mixed. Japanese Patent Application Laid-Open No. 61-249059 discloses a method in which hydrophobic silica and hydrophilic silica are mixed.
In JP-A-0053, a positive additive and a negative additive are mixed. These improvements have ameliorated the disadvantages of the additives. However, the flowability of the low-temperature fixing toner is further deteriorated. A toner using a low softening point resin or a wax has a disadvantage that the fluidity itself is still insufficient.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner using a resin having a low softening point or a wax, which has a good fluidity and avoids a decrease in toner charge.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for producing an electrophotographic toner having base particles containing at least a binder resin and a release agent as main components. And wherein the base particles contain a polyester resin as the binder resin, and as the release agent, a free fatty acid type carnauba wax having an acid value of 5 or less, a montan ester wax, and an oxidized rice having an acid value of 10 to 30. The binding tree containing at least one member selected from the group consisting of wax;
The mixture of the fat and the release agent was heated and melted, and after cooling, the resulting mixture was obtained.
The mixture was pulverized and further classified to obtain base particles.
The body particles are mixed with an additive that reduces the charge amount of the base particles first, and then mixed with an additive that increases the charge amount .
Producing a toner for electrophotography.
You.

Hereinafter, the present invention will be described in more detail. In the present invention, an additive having a charge amount separated from the charge of the base particles enhances the adhesion to the base particles, and furthermore, reduces the charge amount.
Increase the charge after mixing the additive in the direction of decreasing
By adding an additive in the direction in which it is caused to flow, the fluidity can be increased without significantly changing the charge amount of the base particles.

The mixing ratio of the additive for decreasing the charge amount and the additive for increasing the charge amount is from 5:95 to 95: 5.
And the content of the additive is, for example, 0.1 to 5.0 parts by weight, preferably 0.2 to 5.0 parts by weight of the whole toner.
If the amount is less than this range, sufficient toner and fluidity cannot be imparted to the toner. Dependencies become too large. The additives used in the present invention include inorganic fine particles such as SiO ₂ (silica), TiO ₂ (titanium oxide), Al ₂ O ₃ (alumina), TiBaO ₃ (barium titanate), and SiC (silicon carbide). Powders can be used, but silica and titanium oxide are particularly preferred. This is because silica and titanium oxide have particularly excellent fluidity improving effects as compared with other additives. Therefore, the flowability is most improved by making at least one of the additives silica or titanium oxide.

[0008] Silica is produced by a conventionally known technique. For example, it can be obtained by a method utilizing a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame. The titanium oxide is manufactured by a conventionally known technique. For example, it can be produced from titanium tetrachloride in an oxidizing or reducing atmosphere. The amount of charge varies depending on the surface treatment of the additive. For example, treatment with an amino group-containing compound increases the charge amount, and treatment with a methyl group compound results in an additive having a reduced charge amount.

In addition, the method of mixing the additives is that the fluidity is slightly improved even if the additive for decreasing the charge amount and the additive for increasing the charge amount are mixed at the same time. When the amount of charge when added is 0 μC / g or more, which is the charge polarity of the original base particles, even if the balance of the additives is broken, the developer does not become reversely charged and provides sufficient fluidity. In addition, it is possible to obtain a uniform image free from transfer omission and transfer failure, to maintain an appropriate toner charge amount, and to maintain a good image density. The amount of charge when an additive for increasing the amount of charge is added is calculated as 2 times the amount of charge of the base particles with the carrier particles.
Within the range, even if the balance of the additives is lost, the charge amount of the developer does not become too high, and a good image can be maintained. It was confirmed that when the additive for reducing the charge amount was mixed first, the adhesive force with the base particles was further increased, and the fluidity was further improved . That is, the charge amount can be stably maintained by holding the additive for reducing the charge amount inside and maintaining the positive polarity on the outermost of the base particles. If the stirring force when mixing the additive that reduces the charge amount is made stronger than the stirring force when mixing the additive that increases the charge amount, the adhesion between the base particles and the additive that reduces the charge amount is increased. And charging stability and fluidity are improved.

In the present invention, a polyester resin is used as a binder resin, and among them, when a polyester resin synthesized from a bisphenoldiol-type alcohol and a monomer containing a polycarboxylic acid as a main component is used, vinyl chloride is used. A good toner can be obtained without impairing the film properties and the color of the color toner. In addition, the fixability at a low temperature is improved.

The polyester resin is obtained by condensation polymerization of an alcohol and a carboxylic acid. Examples of the alcohol used include ethylene glycol, diethylene glycol, triethylene glycol, and 1,2-glycol. Propylene glycol, 1,3-propylene glycol, 1,
4-butanediol, neopentyl glycol, 1,4
-Diols such as butenediole, 1,4-bis (hydroxymethyl) cyclohexane, and bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylene oxidized bisphenol And ether dibisphenols such as -A and other divalent alcohol monomers. Examples of the carboxylic acid include, for example, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, Examples thereof include malonic acid, an inorganic substance of these acids, a dimer of a lower alkyl ester and linoleic acid, and other divalent organic acid monomers. It is also preferable to use not only a polymer composed of only the above-mentioned difunctional monomer but also a polymer containing a component composed of a trifunctional or more polyfunctional monomer. Examples of the trifunctional or higher polyhydric alcohol monomer which is the polyfunctional monomer include, for example, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentane Erythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanthrol, 1,
2,5-pentantriol, glycerol, 2-methylpropanetriol, 2-methylpropanetriol
2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane,
5-trihydroxymethylbenzene and the like can be mentioned.

[0012] Examples of the trivalent or higher polyvalent carboxylic acid monomer include 1,2,4-benzenetricarboxylic acid and
1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-
Hexanetricarboxylic acid, 1,3-digarboxyl-2
-Methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, embol trimer acid, and acid anhydrides thereof.

The above-mentioned components composed of a trifunctional or higher-functional polyfunctional monomer are contained in a proportion of 30 to 80 mol% in each of the alcohol component or the acid component as a structural unit in the polymer. Is desirable.

The polyester resin is, for example, usually poly-
And a polyvalent carboxylic acid component in an inert gas atmosphere at a temperature of 180 to 250 ° C.

Further, 1 / in an elevated flow tester
(2) A polyester resin having an outflow temperature of 110 to 145 ° C is used. The 1/2 outflow temperature is a value obtained by using an elevated type float tester CFT = 500 manufactured by Shimadzu Corporation.
The measurement conditions were a load of 20 kg, a die diameter of 1.0 mm, a temperature rising rate of 3 ° C./min, and a temperature at which the sample flowed out by half. When the 1/2 outflow temperature is 110 ° C. or lower, the blocking property of the toner deteriorates, and the storage stability deteriorates. If the 1/2 outflow temperature is 145 ° C. or higher, low-temperature fixing of the toner becomes impossible, so the 1/2 outflow temperature is 110 to 145.
C. is preferred.

The particle size of the base particles is preferably 5 to 20 μm.
In the case of a polyester resin having a 流出 outflow temperature of 110 to 145 ° C., even a mother particle having a small particle size of 5 to 10 μm has sufficient fluidity to form a high quality image.

The release agent used in the toner of the present invention is a product in which free fatty acids are released from carnauba wax as a raw material, resulting in an acid value of 5% or less and a conventional release agent. Of carnauba wax, the dispersed particle diameter in the binder resin becomes 1 μm or less, and the dispersibility is improved.

The montan ester wax is refined from a mineral, and becomes microcrystals like carnauba wax, the dispersed particle diameter in the binder resin becomes 1 μm or less, and the dispersibility is improved. In the case of montan ester wax, the acid value is particularly preferably 5 to 14. The oxidized rice wax of the present invention is obtained by oxidizing rice bran wax with air. The acid value is preferably from 10 to 30, and if it is less than 10, the fixing lower limit temperature rises and the low-temperature fixability becomes insufficient. If it is more than 30, the cold offset temperature rises and the low-temperature fixability also becomes insufficient.
Further, the above wax may be used alone or in combination, and 1 to 15 parts by weight, preferably 2 to 15 parts by weight of the whole toner
By including 10 parts by weight, the above-mentioned good results can be obtained.

Coloring agents which may be added to the base particles include carbon black, lamp black, iron black, aniline blue, phthalocyanine blue, phthalocyanine green, Hanseiro-G, Rhodamine 6G, Any conventionally known dyes and pigments, such as dyes and pigments such as yellow, calco oil bull, chrom yellow, quinacridone, benzidine yellow, rosbengal, triallylmethane dyes, can be used alone or in combination. The use amount of these coloring agents is usually 1 to 30% by weight based on the binder resin,
Preferably it is 3 to 20 wt%.

A polarity controlling agent may be added to the base particles. As the + polarity controlling agent, nibrosine dyes, quaternary ammonium salts and the like are generally widely used. The appropriate amount of these polarity control agents is usually 0.1 to 5% by weight.

The method for producing the base particles may be a conventionally known method. For example, a binder resin, a coloring agent, a wax, a charge controlling agent, etc. are melt-kneaded with a hot roll, and then cooled and singulated. Is crushed by a crusher such as a jet mill and classified.

As a method for mixing the additives with the base particles, a conventionally known method may be used, and the additives can be mixed with a device such as a Henschel mixer or a speed mixer. For example, when a Henschel mixer is used, the base particles may be charged into the mixing tank and added at the same time, but a predetermined amount of an additive for reducing the charge amount is added and mixed to further increase the charge amount. The effect is enhanced by adding and mixing a predetermined amount of additives.

The toner for developing an electrostatic latent image can also be used as a dry two-component developer. The amount of the carrier and toner used as the developer is such that the toner particles adhere to the carrier surface of the carrier particles, and 30 to 90% of the surface area thereof.
It is preferable to mix both particles to such an extent that

The carrier may be a conventionally known carrier.
Non-coated carrier such as iron powder and ferrite, styrene
Carriers coated with acrylic resin, silicone resin, fluorine-modified acrylic resin, etc., granulated carriers, etc. can be used. Silicone-coated carriers have low surface energy, and therefore have durability and the like. And is generally used.

[0025]

The present invention will be described below in more detail with reference to examples. In addition, the part in an Example shows a weight part.

Example 1 Polyester resin (number average molecular weight = 5000, 81 parts Weight average molecular weight = 55000, Tg = 62 ° C.) 4 parts of free fatty acid type carnauba wax (acid value 2) Carbon black (Mitsubishi Carbon Co., Ltd.) Bonn # 44) 12 parts Quaternary ammonium salt compound, Bontron P-51 (manufactured by Orient Chemical Co.) 3 parts The mixture having the above composition was sufficiently stirred and mixed in a Henschel mixer, and then 80-110 using a roll mill. About 40 ° C
The resulting kneaded product was pulverized and classified to obtain base particles having a particle size of 5 to 20 μm. For 3 parts of the base particles, a silicone resin (SR-24) was used.
11: 100-250 coated with Toray Silicone Co., Ltd.
When 97 parts of the mesh ferrite carrier was mixed with a ball mill and the charge amount of the base particles with the carrier particles was measured, the charge amount of the base particles was +25 μc / g.

The base particles obtained by the above method were used as an additive for reducing the charge amount per 1 kg of silica fine powder (R).
972, manufactured by Aerosil) Henschel
Using a mixer, mixing was performed at a rotation speed of 1000 rpm.
Thereafter, titanium oxide fine powder is used as an additive to increase the charge amount.
Powder (Titanium Dioxide P25, Ae
(Produced by Rogil) at a rate of 3 g at a rotation speed of 1000 rpm
I combined. Using this toner, fluidity and cohesion were examined.
Fluidity with a powder tester (made by Hosokawa Micron)
Measurement of indices (angle of repose, degree of compression, angle of spatula, degree of cohesion)
Was performed. The higher the flow index, the more fluidity and cohesiveness
good. Then, in order to confirm the charging stability,
100,000 copies can be made with the copier FT-4820.
The charge was measured. The change in charge amount is small,
The charging stability is very good. In addition, the base particles are reduced to 1 kg.
Silica fine powder as an additive to reduce the charge amount
(R972, manufactured by Aerosil Co., Ltd.)
Mix at 1000 rpm using a well mixer.
Was. The charge amount of the toner obtained by this mixing is measured.
It turned out to be +5 μc / g. This is charged amount 1
And Then oxidized as an additive to increase the charge
Titanium Dioxide P2
5, Aerosil Co., Ltd.) 3g, rotation speed 1000r
pm. Charge of toner obtained by this mixing
When the amount was measured, it was +45 μc / g. This
This is referred to as charge amount 2. Table 1 shows the above results. Table 1
As can be seen, the additives that reduce the charge
By doing so, the adhesion to the base particles increases and the fluidity improves.
And holding the additive that reduces the charge amount inside,
By holding the positive electrode on the outermost side of the particles, the chargeability is remarkable.
It can be seen that it is kept stable and stable.

REFERENCE EXAMPLE 1 The base particles obtained by the method of Example 1 were mixed with an acrylic fine powder (MP-
1451, manufactured by Soken Kagaku Co., Ltd.) and 5 g of acrylic fine powder (MP-2701, manufactured by Soken Kagaku Co., Ltd.) as an additive for increasing the charge amount were simultaneously mixed at a rotation speed of 1000 rpm using a Henschel mixer. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As seen from Table 1, bets toner is excellent in fluidity, charging stability.

REFERENCE EXAMPLE 2 The base particles obtained by the method of Example 1 were mixed with an acrylic fine powder (MP-
1451, manufactured by Soken Chemical Co., Ltd.) and 5 g of alumina oxide fine powder (Aluminium) as an additive to increase the charge amount
(Oxide C, manufactured by Aerosil Co., Ltd.) at a rate of 5 g using a Henschel mixer at 1,000 rpm. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1 ,
DOO toner is excellent in fluidity, charging stability.

Comparative Example 1 The base particles obtained by the method of Example 1 were added to 5 g of silica fine powder (Aerosil 200, manufactured by Aerosil Co.) as an additive that hardly changes the charge amount per 1 kg, and the charge amount hardly changed. Silica fine powder (H
(2000, manufactured by Aerosil Co., Ltd.) at the same time with a Henschel mixer at a rotation speed of 1000 rpm at a ratio of 5 g. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, the toner of this comparative example is inferior in fluidity.

Comparative Example 2 The base particles obtained by the method of Example 1 were added as fine particles of alumina oxide (A
luminium Oxide C, manufactured by Aerosil Co., Ltd.)
Only 5 g of one kind was simultaneously mixed using a Henschel mixer at a rotation speed of 1000 rpm. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, the toner of the present comparative example is inferior in charging stability.

REFERENCE EXAMPLE 3 The base particles obtained by the method of Example 1 were used as an additive for reducing the charge amount per 1 kg of silica fine powder (R97).
2, Aerosil Co., Ltd.) 5 g and alumina oxide fine powder (Aluminium Ox) as an additive to increase the charge amount
(ide C, manufactured by Aerosil Co., Ltd.) at a rate of 5 g using a Henschel mixer at 1,000 rpm. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, it is found that the flowability is improved by using the silica fine powder as one of the additives.

Reference Example 4 The base particles obtained by the method of Example 1 were mixed with silica fine powder (MP-1
451, manufactured by Soken Kagaku Co., Ltd.) and titanium oxide fine powder (Titanium Dio) as an additive to increase the charge amount
(Xide P25, manufactured by Aerosil Co., Ltd.) at a rate of 5 g using a Henschel mixer at 1000 rpm. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, the use of titanium fine powder as one of the additives improves the fluidity.

Reference Example 5 The base particles obtained by the method of Example 1 were mixed with silica fine powder (R97
2, 3 g of Aerosil Co., Ltd. and titanium oxide fine powder (Titanium Diox) as an additive to increase the charge amount
(ide P25, manufactured by Aerosil Co., Ltd.) at a rate of 5 g using a Henschel mixer at 1,000 rpm. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1,
By adjusting the amount of the additive for reducing the charge amount, the charge amount 1 is the charge polarity of the original base particles and 0 μc / g.
From the above, it can be seen that the charge amount is stably maintained.

Reference Example 6 The base particles obtained by the method of Example 1 were mixed with silica fine powder (R97
2, 3 g of Aerosil Co., Ltd. and titanium oxide fine powder (Titanium Diox) as an additive to increase the charge amount
(ide P25, manufactured by Aerosil Co., Ltd.) at a rate of 3 g using a Henschel mixer at 1,000 rpm. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1,
By adjusting the amount of the additive for reducing the charge amount, the charge amount 1 is the charge polarity of the original base particles and 0 μc / g.
From the above, it can be seen that the charge amount 2 is within twice the charge amount of the base particles, and the charge amount is stably maintained.

Reference Example 7 The base particles obtained by the method of Example 1 were used as an additive for reducing the charge amount per 1 kg of silicon carbide fine powder (GC
# -1000, manufactured by Fujimi Abrasive Industry) at a rate of 5 g
Using a Henschel mixer at 1000 rpm
After mixing, alcohol oxide is used as an additive to increase the charge amount.
Mina fine powder (Aluminium Oxide C, Ae
(Rosyl) using a Henschel mixer at a ratio of 5 g
And mixed at a rotation speed of 1000 rpm. The results are shown in Table 1.
You. As can be seen from Table 1, the toner has fluidity and charge stability.
It turns out that it is excellent.

REFERENCE EXAMPLE 8 Titanium oxide fine powder (Ti) was used as an additive to increase the charge amount per kg of the base particles obtained by the method of Example 1.
(Tanium Dioxide P25, manufactured by Aerosil Co., Ltd.) 3 g of silica fine powder (R972, manufactured by Aerosil Co., Ltd.) as an additive for reducing the charge amount after mixing at the same time at 1000 rpm using a Henschel mixer. At 1000 rpm. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, this reference
It can be seen that the order of addition of the examples is inferior in fluidity and charging stability as compared with Example 1 .

Example 2 The base particles obtained by the method of Example 1 were mixed with silica fine powder (R97
2, manufactured by Aerosil Co., Ltd.) 3 g in advance by using a Henschel mixer at a rotation speed of 2,000 rpm, and then finely powdered titanium oxide (Ti
(Tanium Dioxide P25, manufactured by Aerosil Co., Ltd.) at a rate of 3 g at a rotation speed of 1000 rpm.
The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, when the additive for decreasing the charge amount is first mixed, the stirring power is increased compared to when the additive for increasing the charge amount is mixed, so that the charge amount of the base particles is reduced. It can be seen that the adhesive force with the additive to be added further increases, and the charging stability and fluidity are remarkably excellent.

Reference Example 9 Polyester resin (1/2 outflow temperature: 136 ° C., number average molecular weight = 5000, weight average molecular weight = 55000, Tg = 62 ° C.) 81 parts Defatty acid fatty acid type carnauba wax (acid value: 2) 4 parts Carbon black (# 44, manufactured by Mitsubishi Carbon Corporation) 12 parts Quaternary ammonium salt compound, Bontron P-51 (manufactured by Orient Chemical Co., Ltd.) 2 parts A mixture having the above composition was prepared in the same manner as in Example 1 to obtain a volume average particle diameter of 8 parts. Base particles having a particle size of 0.5 μm and a particle size of 5 to 10 μm were obtained. A silicone resin (SR-
2411; 100-2 coated with Toray Silicone Co., Ltd.)
When 97 parts of a 50-mesh ferrite carrier were mixed with a ball mill and the charge amount of the base particles with the carrier particles was measured, the charge amount of the base particles was +20 μc / g. Silicon carbide fine powder (GC #) is used as an additive to reduce the charge amount per 1 kg of the base particles obtained by the above method.
5 g of -10000, manufactured by Fujimi Polishing Industry Co., Ltd.
(Ium Oxide C, manufactured by Aerosil Co., Ltd.) was simultaneously mixed at a rotation speed of 1000 rpm using a Henschel mixer at a ratio of 5 g to obtain the toner of the present invention. The same measurement as in Example 1 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, bets toner is excellent in fluidity, charging stability. In addition, the copy image starts and 100
At K point, there was no difference and the image quality was extremely good, and the fixing property was also good.

REFERENCE EXAMPLE 10 The base particles obtained by the method of Reference Example 9 were added to an acrylic fine powder (MP-
1451, manufactured by Soken Kagaku Co., Ltd.) and 5 g of acrylic fine powder (MP-2701, manufactured by Soken Kagaku Co., Ltd.) as an additive for increasing the charge amount were simultaneously mixed at a rotation speed of 1000 rpm using a Henschel mixer. The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, bets toner is excellent in fluidity, charging stability.

REFERENCE EXAMPLE 11 The base particles obtained by the method of Reference Example 9 were mixed with an acrylic fine powder (MP-
1451, manufactured by Soken Chemical Co., Ltd.) and 5 g of alumina oxide fine powder (Aluminium) as an additive to increase the charge amount
(OxideC, manufactured by Aerosil Co., Ltd.) 5 g at the same time using a Henschel mixer at 1,000 rpm. The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, DOO <br/> toner is excellent in fluidity, charging stability.

Comparative Example 3 The base particles obtained by the method of Reference Example 9 were added with 5 g of silica fine powder (Aerosil 200, manufactured by Aerosil Co.) as an additive that hardly changes the charge amount per 1 kg, and the charge amount hardly changed. Silica fine powder (H
(2000, manufactured by Aerosil Co., Ltd.) at the same time at a rotation speed of 1000 rpm using a Henschel mixer. The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, the fluidity of the toner of this comparative example is inferior.

Comparative Example 4 The base particles obtained by the method of Reference Example 9 were used as an additive for increasing the charge amount per 1 kg of alumina fine powder (A
luminium Oxide C, manufactured by Aerosil) 5
g only one type using a Henschel mixer, rotation speed 1
000 rpm at the same time. Using this toner,
The same measurement as in Reference Example 9 was performed. The results are shown in Table 1.
As can be seen from Table 1, the toner of the present comparative example is inferior in charging stability.

REFERENCE EXAMPLE 12 The base particles obtained by the method of Reference Example 9 were mixed with silica fine powder (R97
2, Aerosil Co., Ltd.) 5 g and alumina oxide fine powder (Aluminium Ox) as an additive to increase the charge amount
(ide C, manufactured by Aerosil Co., Ltd.) at a rate of 5 g using a Henschel mixer at 1,000 rpm. The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, it is found that the flowability is improved by using the silica fine powder as one of the additives.

REFERENCE EXAMPLE 13 The base particles obtained by the method of Reference Example 9 were mixed with silica fine powder (MP-1
451, manufactured by Soken Kagaku Co., Ltd.) and titanium oxide fine powder (Titanium Dio) as an additive to increase the charge amount
(Xide P25, manufactured by Aerosil Co., Ltd.) at a rate of 5 g using a Henschel mixer at 1000 rpm. The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, the use of titanium fine powder as one of the additives improves the fluidity.

REFERENCE EXAMPLE 14 The base particles obtained by the method of Reference Example 9 were mixed with silica fine powder (R97
2, 3 g of Aerosil Co., Ltd. and titanium oxide fine powder (Titanium Diox) as an additive to increase the charge amount
(ide P25, manufactured by Aerosil Co., Ltd.) at a rate of 5 g using a Henschel mixer at 1,000 rpm. The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1,
By adjusting the amount of the additive that reduces the charge amount, the charge amount 1 becomes 0 μc / g or more, and it can be seen that the charge amount is stably maintained.

REFERENCE EXAMPLE 15 The base particles obtained by the method of Reference Example 9 were mixed with silica fine powder (R97
2, 3 g of Aerosil Co., Ltd. and titanium oxide fine powder (Titanium Diox) as an additive to increase the charge amount
(ide P25, manufactured by Aerosil Co., Ltd.) at a rate of 3 g using a Henschel mixer at 1,000 rpm. The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1,
By adjusting the amount of the additive that reduces the charge amount, the charge amount 1 becomes 0 μc / g or more, and it can be seen that the charge amount is stably maintained.

Example 3 The base particles obtained by the method of Reference Example 9 were mixed with silica fine powder (R97
2, Aerosil Co., Ltd.) 3 g at a rotation speed of 1,000 rpm using a Henschel mixer, and then finely powdered titanium oxide (Ti
(Tanium Dioxide P25, manufactured by Aerosil Co., Ltd.) at a rate of 3 g at a rotation speed of 1000 rpm.
The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, by first mixing the additive for decreasing the charge amount, the adhesive force with the base particles is increased, the fluidity is remarkably improved, and the additive for decreasing the charge amount is held inside, It can be seen that the chargeability is extremely stably maintained by holding the positive electrode on the outermost side of the base particles.

REFERENCE EXAMPLE 16 The base particles obtained by the method of Reference Example 9 were added as fine particles of titanium oxide (Ti
(Tanium Dioxide P25, manufactured by Aerosil Co., Ltd.) 3 g of silica fine powder (R972, manufactured by Aerosil Co., Ltd.) as an additive for reducing the charge amount after mixing at the same time at 1000 rpm using a Henschel mixer. At 1000 rpm. The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, this reference
It can be seen that, in the order of addition of the examples , fluidity and charging stability are inferior to Example 3 .

Example 4 The base particles obtained by the method of Reference Example 9 were mixed with silica fine powder (R97
2, manufactured by Aerosil Co., Ltd.) 3 g in advance by using a Henschel mixer at a rotation speed of 2,000 rpm, and then finely powdered titanium oxide (Ti
(Tanium Dioxide P25, manufactured by Aerosil Co., Ltd.) at a rate of 3 g at a rotation speed of 1000 rpm.
The same measurement as in Reference Example 9 was performed using this toner. The results are shown in Table 1. As can be seen from Table 1, when the additive for decreasing the charge amount is first mixed, the stirring power is increased compared to when the additive for increasing the charge amount is mixed, so that the charge amount of the base particles is reduced. Adhesion with additives to be added is further increased, and charging stability and fluidity are extremely high
It turns out that it is excellent. Table 1 is shown on the next page.

[Table 1]

[0051]

As described above, the dry toner according to the present invention has (1) sufficient fluidity, (2) low-temperature fixation, high-speed fixation, and (3) sufficient correctability. It has the advantage of imparting chargeability, having excellent charge stability, and being able to form high quality images.

Continuation of the front page (72) Inventor Mitsuo Aoki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-3-12664 (JP, A) JP-A-2-282753 (JP, A) JP-A-1-238672 (JP, A) JP-A-1-109360 (JP, A) JP-A-5-5764 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) G03G 9/08-9/087

Claims (1)

(57) [Claims] 1. A method for producing an electrophotographic toner having at least a binder resin and a base particle mainly composed of a release agent, wherein the base particle contains a polyester resin as the binder resin. In addition, the release agent contains at least one selected from the group consisting of a free fatty acid-type carnauba wax having an acid value of 5 or less, a montan ester wax, and an oxidized rice wax having an acid value of 10 to 30; Tree
The mixture of the fat and the release agent was heated and melted, and after cooling, the resulting mixture was obtained.
The mixture was pulverized and further classified to obtain base particles.
The body particles are mixed with an additive that reduces the charge amount of the base particles first, and then mixed with an additive that increases the charge amount .
Method for producing a toner for electrophotography which is characterized in that that.