JPH0467155A - Manufacture of toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To eliminate dispersion of a charge quantity among each of the toner particles by suspension-polymerizing a monomer in the presence of a colorant and adding a charge controller into the obtained aqueous dispersion to attach the controller to each colored polymer particle. CONSTITUTION:The colorant is uniformly mixed with the monomer liquid, and a polymerization initiator is added to form an oil phase. This oil phase is added into an aqueous phase prepared by uniformly dispersing a dispersion adjuvant, and the oil drops are dispersed with a continuous dispersing machine to reduce the diameters of the drops to a value suitable for the toner. This dispersion is supplied into a polymerization reactor provided with a stirrer, a condenser, a thermometer, a nitrogen introducing tube, and the reactor is heated to the decomposition point of the polymerization initiator and polymerization is carried out in an atmosphere of nitrogen. At the end of the polymerization, the charge controller is added to the polymer liquid dispersion, and further stirred to attach the charge controller to the surface of each polymer particle, thus permitting the obtained toner to be free from dispersion of the charge quantity among each toner particle and small in reverse charging.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a dry toner for developing electrostatic images in electrophotography, electrostatic recording, and electrostatic printing.

[Prior art and problems to be solved by the invention] A developing method using a dry toner whose main components are a colorant and a resin is as follows: (1) The dry toner is mixed with a carrier having a particle size larger than the toner, and the dry toner is mixed with a carrier having a particle size larger than the toner, and then the toner is charged by friction. A method using a two-component developer in which the toner is charged with a polarity opposite to that of the electrostatic latent image, and a developer, which is a mixture of toner and carrier, is brought into contact with the electrostatic latent image to develop the electrostatic latent image. 2) There is a method using a one-component developer in which a toner containing a magnetic material is brought into contact with or in close proximity to an electrostatic latent image.

Conventionally, in order to obtain these toners, thermoplastic resin was melted, coloring agents such as dyes and pigments, and if necessary magnetic materials, tribostatic charge control agents, anti-offset agents, lubricants, etc. were added and thoroughly mixed. After that, it is cooled and solidified, and then finely pulverized.
Methods of classification have been implemented to obtain the required particle size.

However, the methods described above have various drawbacks. That is, there are drawbacks that lead to increased costs, such as the number of steps and equipment being large and the steps being complicated, high energy consumption, and poor yield for obtaining a desired particle size range.

Furthermore, since the obtained powder has an amorphous shape, there are also disadvantages such as poor fluidity and fogging of images caused by fine powder generated by pulverization by stirring during frictional charging.

In contrast, Special Publication No. 36-10231, Special Publication No. 47
Publications such as Japanese Patent Publication No. 518305 and Japanese Patent Publication No. 14895/1989 describe methods for producing toners by suspension polymerization. This suspension polymerization method does not require pulverization, the manufacturing process is simplified, and it can be said that the above-mentioned drawbacks have been improved. However, in the suspension polymerization method, the amount of charge control agent varies between toner particles depending on the dispersion state of the charge control agent, resulting in variations in the amount of charge. Furthermore, since charge control agents are present inside toner particles that do not contribute to triboelectric charging, expensive charge control agents are generally not used effectively.

In order to solve these problems, Japanese Patent Laid-Open Publications No. 138358/1982 and No. 10263/1988 disclose methods of fixing a charge control agent to toner particles by mechanical force. These methods can be said to be methods that have improved the above problems. However, in these methods, the charge control agent peels off during continuous use and becomes spent, deteriorating the carrier and deteriorating the image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner and a method for producing the toner that improve the above-mentioned drawbacks.

That is, the first object of the present invention is to provide a method for manufacturing a toner in which a charge control agent is uniformly adhered to the surface of the toner and eliminates variations in the amount of charge between toners. It is an object of the present invention to provide a toner that has sufficient charging properties even with a charge control agent of 100% and provides excellent image quality over multiple printings.

[Means to solve the problem]

In order to achieve the above object, the present inventors have made extensive efforts to carry out suspension polymerization of a polymerizable monomer in the presence of a colorant, and then dispersion of the resulting colored polymer particles in water. By adding a charge control agent to the liquid and adhering the charge control agent to the colored polymer particles, the charge control agent is uniformly fixed to the toner,
The inventors have discovered that sufficient chargeability can be imparted even with a small amount of charge control agent, that the charge amount distribution is improved, and that a toner with superior durability than dry methods or the like can be obtained, leading to the present invention.

That is, the present invention comprises a step of suspension polymerizing a polymerizable monomer in the presence of a colorant to obtain colored polymer particles, and adding a charge control agent to an aqueous dispersion of the colored polymer particles to obtain the colored polymer particles. The present invention relates to a method for producing a toner for developing an electrostatic image, which comprises a step of attaching a charge control agent to polymer particles.

Hereinafter, the method for producing the toner of the present invention will be explained by giving preferred specific examples.

As the polymerizable monomer used in the present invention, polymerizable monomers can be used, such as styrene, p-chlorostyrene, p-methylstyrene, vinyl acetate, vinyl propionate, vinyl benzoate, Methyl acrylate, ethyl acrylate, n-butyl acrylate, acrylic acid i
s.

-butyl, dodecyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 1so-butyl methacrylate, dimethylaminoethyl methacrylate, t-butyl methacrylate Aminoethyl, acrylonitrile, 2-vinylpyridine, 4-vinylpyridine and the like can be used alone or in combination.

Furthermore, in the present invention, by adding polyfunctional monomers such as divinylbenzene, ethylene glycol dimethacrylate, trimethylpropane triacrylate, glycidyl acrylate, and glycidyl methacrylate to the above-mentioned polymer as a crosslinking agent, the durability can be further improved. toner can be produced.

In the case of black toner, the colorant used in the present invention includes thermal black method, acetylene black method,
In the case of various carbon blacks and color toners produced by the channel black method, furnace black method, etc., examples include copper phthalocyanine, monoazo pigments, disazo pigments, anthraquinone pigments, disazo dyes, rhodamine dyes, and the like. The amount of the colorant used is preferably 5 to 15% by weight based on the polymerizable monomer.

In the present invention, as the polymerization initiator, an oil-soluble peroxide type or azo type initiator used for -C can be used. For example, benzoyl peroxide, lauroyl peroxide, 2
, 2''-azobisisobutyronitrile, 2.2°-azobis(2,4-dimethylvaleronitrile), orthochlorhendiyl peroxide, orthomethoxybenzoyl peroxide, etc. These may be used alone or in combination of two or more. The amount of the polymerization initiator used is preferably 0.5 to 10% by weight, particularly preferably 1 to 7% by weight, based on the polymerizable monomer.

In the suspension polymerization of the present invention, a dispersion stabilizer such as a water-soluble polymer or a poorly water-soluble inorganic powder can be used. Preferably, poorly water-soluble inorganic powders such as barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, and calcium phosphate are used, and hydroxyapatite is particularly preferably used. These may be used alone or in combination of two or more, and a surfactant may be used in combination as a dispersion aid. The amount of these dispersion stabilizers used is preferably 0.1 to 30% by weight of water, particularly preferably 1 to 1% by weight.
It is 0% by weight.

As the charge control agent used in the present invention, any known charge control agent, either positively chargeable or negatively chargeable, may be used in a normally used amount. For example, a negative toner can be obtained using a negatively chargeable charge control agent such as an azo complex dye. Specific examples of negatively chargeable charge control agents include Eizenspiron Black TRI (, T77 (Hodogaya Chemical Industry ■), Bontron S34.S37.540 (Orient Chemical Industry ■), Kayaset Black T2 (Nippon Kayaku @), Prodonor CCA3, CCA7 (ICI Japan), etc.Also, a positive toner can be obtained by using a positively chargeable charge control agent such as nigrosine.As a positively chargeable charge control agent, Specifically, Bontron NO.
7 (Orient Chemical Industry ■), TP415 (Hodogaya Chemical Industry ■), and the like. Further, in the case of a color toner, a colorless and transparent or white charge control agent that does not affect the color tone is preferable. As such a charge control agent, TP302
(Hodogaya Chemical Industry ■), Kaya Charge Nl, N2 (
TRIBLOX PCloo (DuPont Japan), etc. The amount of charge control agent used in the present invention is 0.01 to 1.0% by weight based on the polymer particles.
is preferred, particularly preferably 0.1 to 065% by weight.

Further, in the present invention, a low molecular weight olefin polymer can be used for purposes such as preventing offset and improving fixing properties. It is preferable that this low molecular weight olefin polymer be present during monomer polymerization together with the charge control agent used in the present invention. The amount of the low molecular weight olefin polymer used is preferably 1 to 20% by weight, particularly preferably 3 to 10% by weight, based on the polymer resin component.

In the polymer particle production process in the present invention, first, a colorant is uniformly mixed into a polymerizable monomer.

In this case, when the colorant is a pigment, it is preferable to uniformly disperse it in the polymerizable monomer using a media type grinder such as a ball mill or Attritor (manufactured by Mitsui Miike Kakoki ■).

Next, a polymerization initiator is added to this to form an oil phase. This oil phase is added to the aqueous phase with added dispersant. Moreover, the weight ratio of the oil phase and the water phase is arbitrarily set within the range of 1:1 to 1:20.

Next, droplets of the oil phase are dispersed in this dispersion using a continuous disperser to a particle size suitable for the toner.

The dispersion liquid in which the oil phase and the aqueous phase are uniformly dispersed is transferred to a polymerization reactor equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube, heated to a temperature at which the polymerization initiator decomposes, and then heated under a nitrogen atmosphere. Polymerization is performed to obtain polymer particles.

The charge control agent attachment step in the present invention is a step in which a charge control agent is added to a polymer dispersion and further stirred. In this case, it is preferable to add a solvent. As the solvent, a solvent having a solubility parameter of 10 or more such as methanol, ethanol, acetone, etc. is preferable, and methanol is particularly preferable, since polymer particles will coalesce if the solubility parameter is too low. Further, the amount of the solvent added is preferably 10 to 100% by weight, particularly preferably 20 to 50% by weight, based on the polymer particles.

Further, the charge control agent is preferably dispersed in the above-mentioned solvent, and in the case of a pigment-type charge control agent, it is particularly preferable to uniformly disperse it using the above-mentioned media type dispersion machine. Furthermore, when stirring is performed after adding the charge control agent, there is no restriction on the temperature, but particularly preferable results can be obtained by heating the mixture to a temperature above the glass transition point and below the softening point of the polymer particles. If the temperature is below the glass transition point, the charge control agent will not adhere efficiently. Moreover, when the softening point is exceeded, coalescence of polymer particles tends to occur, and the toner particle size distribution tends to change. In the present invention, the glass transition point is measured by a differential scanning calorimeter (DSC) at a heating rate of 10°C/min, and is defined as the temperature at the intersection of the tangent line and the baseline at the maximum slope of the endothermic curve. Let it be the glass transition point. The softening point is measured using a flow tester CFT500 manufactured by Shimadzu Corporation, and is for sample 1.2.
The softening point is defined as the temperature at which 0.6 g of the sample flows out under the following conditions after g is injected.

Measurement conditions Nozzle = lIllIllφ×11III11
, Load = 30 kg, Temperature rising rate: 6°C/min To specifically explain the manufacturing method of the present invention, first, a colorant is uniformly mixed into a polymerizable monomer.

Next, a polymerization initiator is added to this to form an oil phase.

This oil phase is added to an aqueous phase in which a dispersion stabilizer such as calcium phosphate and a dispersion aid such as an anionic surfactant are uniformly dispersed, and a continuous disperser is used to add the oil to the particle size suitable for the toner. Disperse the phase droplets, transfer this dispersion to a polymerization reactor equipped with a stirring device, a condenser thermometer, and a nitrogen inlet tube, raise the temperature to a temperature at which the polymerization initiator decomposes, and conduct polymerization under a nitrogen atmosphere. let After the polymerization is completed, a charge control agent is added to the polymer dispersion and further stirred to adhere the charge control agent to the surface of the polymer particles. After completion of this adhesion step, hydrochloric acid is added to dissolve the phosphate, the aqueous phase is removed by filtration, and after washing with water, water is removed by means such as spray drying or vacuum drying to obtain the toner of the present invention.

〔Example〕

Examples of the present invention are shown below, but the present invention is not limited thereto.

Note that "parts" in the examples are "parts by weight."

Example 1 To 80 parts of styrene and 20 parts of n-butyl acrylate, 10 parts of carbon black (manufactured by Mitsubishi Kasei ■, 1144) and 2 parts of low molecular weight polyethylene wax (manufactured by Mitsui Petrochemical Industries ■, Mitsui Hiwax 210P) were added. Attritor (
A polymerizable monomer composition dispersed for 6 hours using Mitsui Miike Kako 1mm> was added with 2 parts of 2.2'-azobisisobutyronitrile and mixed with 400 parts of ion-exchanged water and a hydroxyapatite aqueous dispersion. (Manufactured by Nippon Kagaku Kogyo ■, Super Thai)
10) Added to a mixture of 30 parts and 0.01 part of sodium dodecylbenzenesulfonate, and mixed and stirred. Next, this mixed liquid is mixed with a continuous dispersion machine using cavitation.
■Feed rate: 251/min (manufactured by Ebara Corporation), rotation speed: 80
The suspension was suspended and dispersed by passing the sample 4 times at 00 rpm. This suspension was stirred in a separable flask at 70°C under a nitrogen atmosphere at a stirring speed of 1100 rpm using an ordinary stirrer.
A time polymerization reaction was performed. After the polymerization is completed, apply a charge control agent (manufactured by Odugaya Chemical Industry, Eisenspiron Black TREI).
) 015 parts to 30 parts of methanol using an attritor6
The dispersion was added for an additional 2 hours, and the mixture was stirred at 70°C for an additional 2 hours. After that, it is cooled, filtered, washed with acid, and washed with water.
It was dried under reduced pressure at 40°C for one day and night to obtain a 6.2-toner.

The resulting toner had a glass transition point of 59.2°C and a softening point of 120.3°C.

Example 2 85 parts of styrene, 15 parts of 2-ethylhexyl acrylate, 10 parts of carbon black (RAVEN2100, manufactured by Columbian Carbon Japan), and low molecular weight polyethylene wax (Mitsui Hiwax 210P, manufactured by Mitsui Petrochemical Industries, Ltd.) 2 parts was added to the polymerizable monomer composition which was dispersed for 6 hours using an attritor (Mitsui Miike Kakoki ■).
, 2'-azobisisobutyronitrile added thereto, 400 parts of ion-exchanged water, 30 parts of hydroxyapatite aqueous dispersion (manufactured by Nihon Kagaku Kogyo ■, Super Thai), and 0.01 parts of sodium dodecylbenzenesulfonate. of the mixture and mixed and stirred. Next, this mixed liquid was mixed at a pressure of 30 kgf/cm'' (gauge pressure) using a hydrolaser (Gorlin Corporation) with a swirling flow type.
It was passed through twice to suspend and disperse it. This suspension was polymerized according to the method of Example 1, and after the polymerization was completed, a charge control agent (manufactured by Orient Kagaku Kogyo ■, Bontron S-34) was used at 0.5%.
5 parts were added to 30 parts of methanol using an attritor for 6 hours, and the resulting mixture was stirred at 70°C for an additional 2 hours.

After that, it was cooled, filtered, washed with acid, and washed with water at 40°C.
The mixture was dried under reduced pressure for a day and a night to obtain a 6.2-toner.

The resulting toner had a glass transition point of 63.2°C and a softening point of 122.3°C.

Example 3 A 6.5-color toner was obtained in accordance with the method of Example 1, except that 0.3 parts of Bontron 5-40, manufactured by Orient Kagaku Kogyo ■, was used as a charge control agent.

The resulting toner had a glass transition point of 58.0°C and a softening point of 121.0°C.

Comparative Example 1 80 parts of styrene, 20 parts of n-butyl acrylate, 10 parts of carbon black (manufactured by Mitsubishi Kasei ■, 144), 0.3 part of a charge control agent (manufactured by Odugaya Chemical Industry ■, Aizen Subiron Black TRFI), Low molecular weight polyethylene wax (manufactured by Mitsui Petrochemical Industries, Mitsui Hiwax 210P)
2 parts of 2.2'-azobisisobutyronitrile was added to the polymerizable monomer composition, which was dispersed for 6 hours using an attritor (Mitsui Miike Kakoki ■), and then mixed with ion-exchanged water. The mixture was added to a mixture of 400 parts of hydroxyapatite aqueous dispersion (Superite 10, manufactured by Nihon Kagaku Kogyo ■) and 0.01 part of sodium dodecylbenzenesulfonate, and mixed and stirred. Next, feed this mixed liquid to Milder, a continuous dispersion machine that uses cavitation (manufactured by Ebara Corporation) in an amount of 25. The mixture was passed through the solution four times at a rotational speed of 8,000 rpm for suspension and dispersion. This suspension was subjected to a polymerization reaction in a separable flask at 70° C. for 18 hours under a nitrogen atmosphere at a stirring speed of 1100 rpm using a conventional stirrer.

After the polymerization is completed, it is cooled, filtered, washed with acid, and washed with water.
It was dried under reduced pressure at 0°C for one day and night to obtain a 6.2-toner.

The resulting toner had a glass transition point of 57.6°C and a softening point of 119.8°C.

Comparative Example 2 80 parts of styrene, 20 parts of n-butyl acrylate, 10 parts of carbon blank (manufactured by Mitsubishi Kasei Corporation, $144), and a charge control agent (manufactured by Orient Chemical Co., Ltd., Bontron S-40)
), 0.3 parts of low molecular weight polyethylene wax (manufactured by Mitsui Petrochemical Industries ■, Mitsui Hiwax 210P) were added, and a polymerizable monomer composition was dispersed for 6 hours using an attritor (Mitsui Miike Kakoki ■). and 2 parts of 2,2"-azobisisobutyronitrile to 400 g of ion-exchanged water.
1 part, 30 parts of a hydroxyapatite aqueous dispersion (Superite 10, manufactured by Nippon Kagaku Kogyo ■), and 0.01 part of sodium dodecylbenzenesulfonate, and the mixture was mixed and stirred. Next, feed this mixed liquid to Milder, a continuous dispersion machine using cavitation (manufactured by Ebara Corporation) in an amount of 251
The mixture was passed through the solution four times at a rotation speed of 800 rpm and suspended/dispersed. This suspension was subjected to a polymerization reaction in a separable flask at 70° C. for 18 hours under a nitrogen atmosphere at a stirring speed of 1100 rpm using a conventional stirrer. After the polymerization was completed, it was cooled, filtered, and washed with acid, resulting in caking.
Didn't get toner.

Comparative Example 3 According to Comparative Example 1, a toner with an average particle size of 6.2- was obtained. Next, to 100 g of this toner, 0.5 of a charge control agent (Eisenspiron Black TRH, manufactured by Odugaya Chemical Industry ■) was added.
g, and with an Ong mill (manufactured by Hosokawa Micron), 2
The mixture was stirred at 000 rpm for 30 minutes to obtain a toner with a charge control agent attached to the surface.

The resulting toner had a glass transition point of 57.6°C and a softening point of 119.8°C.

The toners obtained in Examples 1 to 3 and Comparative Examples 1 and 3 above were subjected to surface treatment by adding 0.3 parts of hydrophobic silica "Aerosil R972J (manufactured by Nippon Aerosil) to 100 parts of toner. A developer was prepared using a resin-coated ferrite carrier so that the toner concentration was 4%.

Regarding these developers, the amount of charge was measured using a blow-off device, and the images were evaluated using a commercially available electrophotographic copying machine. The results are shown in Table 1.

Table note: Evaluation criteria ○: Good Δ: Practical ×: Not practical By the toner production method of the present invention in which a charge control agent is attached to a toner, a toner with no variation in charge amount between toners, that is, with little reverse charge, can be obtained, and even with a small amount of charge control agent, sufficient chargeability can be obtained. It has become easier to produce toner that can provide excellent image quality over multiple prints.

Claims (1)

[Claims] 1. A step of suspension polymerizing a polymerizable monomer in the presence of a colorant to obtain colored polymer particles, and adding a charge control agent to an aqueous dispersion of the colored polymer particles; A method for producing a toner for developing an electrostatic image, comprising the step of attaching a charge control agent to the colored polymer particles. 2. The method for producing a toner for developing electrostatic images according to claim 1, wherein a poorly water-soluble inorganic powder is used as a dispersion stabilizer in the suspension polymerization. 3. The method for producing an electrostatic image developing toner according to claim 1, wherein in the step of attaching the charge control agent, the polymer particles are heated to a temperature above the glass transition point and below the softening point.