JP2003066649A - Electrostatic charge image developing toner and method for manufacturing electrostatic charge image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing toner yielding high picture quality and having excellent durability. SOLUTION: The toner contains at least a resin and a coloring agent and is obtained by an emulsion polymerization aggregation method including an emulsion polymerization process, an aggregation process and an ageing process. The toner is subjected to defoaming treatment in the aggregation process and/or the ageing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge image developing toner and a method for producing an electrostatic charge image developing toner. More specifically, the present invention relates to an electrostatic charge image developing toner used in electrophotographic copying machines and printers. More specifically, the present invention relates to a toner for developing an electrostatic charge image, in which a clear image having a sharp particle size distribution can be obtained, and high transferability and high durability can be obtained by freely controlling the sphericity, and a method for producing the same.

[0002]

2. Description of the Related Art Toners for developing electrostatic images, which have been widely used in the past in electrophotography, include resins such as styrene / acrylate copolymers, colorants such as carbon black and pigments, and charge control agents. It has been produced by melt-kneading a mixture containing a magnetic material and / or an extruder, and then pulverizing and classifying. However, the conventional toner obtained by the melt kneading and pulverization method as described above has a limitation in controlling the particle diameter of the toner, and is substantially 10 μm or less, particularly
It is difficult to produce a toner having an average particle diameter of μm or less with a high yield, and it cannot be said to be sufficient to achieve the high resolution required for future electrophotography.

In Japanese Patent Laid-Open No. 63-186253, in order to overcome the problem of particle size control and achieve high resolution,
A method for producing a toner by an emulsion polymerization aggregation method has been proposed. In this method, the particle size distribution is improved compared to the melt-kneading and pulverization method, but it is not always sufficient, and if the melt viscosity is designed to be high, it is difficult to raise the sphericity sufficiently, and transferability and durability are improved. I had a problem with. Furthermore, the method disclosed in Japanese Patent Laid-Open No. 6-329947 is a method of adding an organic solvent that is infinitely soluble in water together with a coagulant in the coagulation step, and is a method capable of obtaining coagulated particles having a narrow particle size distribution. However, there are problems such as poor reproducibility due to the large number of control factors, and a large burden on wastewater treatment.

[0004]

SUMMARY OF THE INVENTION The present invention provides a novel toner that overcomes the drawbacks of the toners for electrostatic image development used hitherto and that satisfies high resolution, high transferability and high durability. Is an issue.

[0005]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that when a toner is manufactured by an emulsion polymerization aggregation method, a specific treatment is carried out in the manufacturing process so that the above problems can be solved. The inventors have found that they can be solved and arrived at the present invention. That is, the gist of the present invention is a toner containing at least a resin and a colorant and obtained by an emulsion polymerization aggregation method including at least an emulsion polymerization step, an aggregation step and an aging step, and defoaming in the aggregation step and / or the aging step. A toner for developing an electrostatic charge image, which has been subjected to a treatment.

Another aspect of the present invention is an emulsion polymerization step in which a monomer mixture containing a monomer having an acidic polar group or a basic polar group is sequentially added to carry out emulsion polymerization, and the obtained polymer primary particle dispersion liquid. And a colorant primary particles and / or a dispersion liquid containing a charge control agent primary particles in an aggregating step of aggregating the primary particles in a mixed solution into a particle aggregate, and heating the dispersion containing the particle aggregate. A method for producing a toner for developing an electrostatic charge image, comprising the step of defoaming in the step of aggregating and / or the step of aging in a method for producing a toner including an aging step of causing fusion.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The production of toner by the emulsion polymerization aggregation method includes at least an emulsion polymerization step, an aggregation step and a ripening step. More specifically, the production of a toner by the emulsion polymerization aggregation method usually includes an emulsion polymerization step, a mixing step, an aggregation step, an aging step, and a washing / drying step.

That is, the production of a toner by the emulsion polymerization aggregation method is usually an emulsion polymerization in which a monomer mixture containing a monomer having an acidic polar group or a basic polar group is sequentially added to carry out emulsion polymerization to obtain polymer primary particles. Step, a mixing step of mixing a dispersion liquid of each primary particle such as a colorant and a charge control agent to the dispersion liquid containing the obtained polymer primary particles, aggregating the primary particles in this dispersion liquid to form a particle aggregate It comprises an aggregating step, an aging step of heating and agglomerating the particle agglomerates, and a washing / drying step of washing and drying the obtained toner particles to obtain product toner particles.

The toner production by the emulsion polymerization aggregation method according to the present invention is characterized in that in the toner production method comprising the above-mentioned steps, defoaming treatment is carried out in the aggregation step and / or the aging step. The defoaming treatment may be performed in either one of the aggregation step and the aging step, or may be performed in both steps. The defoaming process mentioned here is a process of breaking bubbles contained in the coagulation liquid.

The defoaming method used in the present invention may be a method of physically defoaming or a method of chemically defoaming using an antifoaming agent. As a method of physically breaking the foam, a method of pressurizing to reduce the volume of the foam, a method of bursting the foam by reducing the pressure, or a method of pouring water to change the temperature and a decrease in the gas phase volume of the container are used. The method of foaming is effective. Above all, the method using reduced pressure is particularly effective.

As a method of chemically defoaming with a defoaming agent, there are a method of adding a low molecular defoaming agent and a method of adding a high molecular defoaming agent. Examples of the low-molecular defoaming agent include alcohols, organic solvents, metallic soaps, mineral oils and the like. Among these, organic solvents such as hexane, xylene and styrene are particularly effective. As the polymer defoaming agent, there are polyether type and silicone type. However, the polymer defoaming agent may adversely affect the chargeability of the toner, so that it should be used with caution.

The toner obtained by the defoaming treatment in the aggregating step and / or the aging step of the present invention has a sharper particle size distribution and a sphericity as compared with the toner which is not subjected to the defoaming treatment. Easy to control.
Particularly in the case of a toner that needs to have a high melt viscosity, it is generally difficult to obtain a toner having a high sphericity, but defoaming treatment facilitates this. Further, the time required for aging to obtain a certain sphericity is shortened, and toner productivity is improved.

Although the reason why the above-mentioned effects are exhibited by the defoaming treatment is not well understood, it is considered that the cohesive force in the emulsion polymerization coagulation method is largely due to the electrostatic force acting between the particles. It is presumed that the presence of bubbles between them weakens the electrostatic force and hinders uniform operation. Regarding the timing of the defoaming treatment, the viscosity of the coagulation liquid increases in the process where the emulsion-polymerized particles start to aggregate and reach suspended particles, but it is particularly effective to perform before and after this process to sharpen the particle size distribution. is there. The defoaming treatment in the aging step in which the interface of the agglomerated particles is thermally fused by further advancing the steps is particularly effective in easily controlling the sphericity.

By performing the defoaming treatment, a toner having a sharp particle size distribution and a toner having a good charging property can be obtained. The effect of this is that even if a small particle size toner is manufactured, good fluidity is exhibited, and it contributes to obtaining a high resolution toner. It also contributes to obtaining a toner having high transferability. By performing the defoaming treatment, a toner with a controlled sphericity can be easily obtained. In the case of a toner with a large sphericity, when it is used for the non-magnetic one-component development, the external additive is compared with the toner with a small sphericity. Is evenly distributed, so that a high-quality image can be obtained, and when a long-life test is performed, there is little embedding of an external additive, so image deterioration is less likely to occur. Further, in the case of development that requires cleaning, such as in the case of two-component development, toner with a small sphericity facilitates cleaning.

In the emulsion polymerization, a monomer having a Bronsted acidic group (hereinafter sometimes referred to as an acidic polar group) or a Bronsted basic group (hereinafter sometimes referred to as a basic polar group) is successively used. Polymerization proceeds by adding a monomer and a monomer having neither a Bronsted acidic group nor a Bronsted basic group (hereinafter, sometimes referred to as other monomer). At this time, the monomers may be added separately, or a plurality of monomers may be mixed in advance and then added. Further, it is possible to change the monomer composition during the addition of the monomer. Further, the monomer may be added as it is, or may be added as an emulsion prepared by mixing and adjusting water and an emulsifier in advance. As the emulsifier, one type or a combination type of two or more types is selected from the surfactants described below.

The monomer having an acidic polar group used in the present invention has a monomer having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and cinnamic acid, and a sulfonic acid group such as sulfonated styrene. Examples thereof include monomers and monomers having a sulfonamide group such as styrene sulfonamide. As the monomer having a basic polar group, a monomer having an amino group such as aminostyrene, a monomer having a nitrogen-containing heterocyclic group such as vinylpyridine and vinylpyrrolidone, dialkyl such as dimethylaminoethyl acrylate and diethylaminoethyl methacrylate. Have an amino group (meth)
Examples thereof include acrylic acid ester.

Other monomers include styrene, methylstyrene, chlorostyrene, dichlorostyrene, p
-T-butyl styrene, pn-butyl styrene, p-
Styrenes such as n-nonylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid (Meth) acrylic acid esters such as propyl, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, ethylhexyl methacrylate and the like can be mentioned. Of these, styrene and butyl acrylate are particularly preferable.

These monomers may be used alone or as a mixture, and the glass transition temperature of the polymer is 40 at that time.
It is preferably -80 ° C. Glass transition temperature is 80
If the temperature exceeds ℃, the fixing temperature may become too high, or the transparency of OHP may deteriorate. On the other hand, if the glass transition temperature of the polymer is lower than 40 ° C, the storage stability of the toner may be too poor. Cause problems. In the present invention, acrylic acid is preferably used as the monomer having an acidic polar group, and styrene, acrylic acid ester and methacrylic acid ester are preferably used as the other monomers.

Examples of the emulsifier used in the emulsion polymerization include an emulsifier selected from cationic surfactants, anionic surfactants and nonionic surfactants. Specific examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl ammonium bromide and the like.

Specific examples of the anionic surfactant include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate and the like. Further, specific examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, and monodecanoyl. Examples include sucrose.

Of these surfactants, alkali metal salts of linear alkylbenzene sulfonic acid are preferred. As the polymerization initiator, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate, etc., and a redox initiator obtained by combining a reducing agent such as sodium acid sulfite with these persulfates as one component, hydrogen peroxide. , 4, 4'-
Water-soluble polymerization initiators such as azobiscyanovaleric acid, t-butyl hydroperoxide, cumene hydroperoxide,
Further, a redox initiator system in which these water-soluble polymerizable initiators are combined as a component with a reducing agent such as a ferrous salt, benzoyl peroxide, 2,2′-azobisisobutyronitrile, etc. are used. These polymerization initiators may be added to the polymerization system before, at the same time as, or after the addition of the monomer, and these addition methods may be combined as necessary.

In the present invention, a known chain transfer agent can be used if necessary. Specific examples of such a chain transfer agent include t-dodecyl mercaptan and 2-
Mercaptoethanol, diisopropylxanthogen,
Examples include carbon tetrachloride and trichlorobromomethane.
The chain transfer agent may be used alone or in combination of two or more kinds, and is usually used in an amount of 0 to 5% by weight based on the polymerizable monomer.

The average particle size of the polymer primary particles is usually 0.0
5 to 3 μm, preferably 0.1 to 1 μm,
More preferably, it is 0.1 to 0.5 μm. The average particle size can be measured using, for example, Microtrack UPA manufactured by Nikkiso Co., Ltd. If the particle size is smaller than the above range, it is difficult to control the aggregation rate, which is not preferable. On the other hand, if it exceeds the above range, the toner particle size obtained by agglomeration becomes too large, which is unsuitable for applications requiring high resolution as the toner.

In the present invention, when polymer primary particles are obtained,
The pigment may be used as a seed at the same time as the wax, or the colorant may be dissolved or dispersed in a monomer or a wax, but the primary particles of the colorant may be aggregated with the polymer primary particles to form associated particles, It is preferably a toner. At this time, it is preferable to use polymer primary particles encapsulating wax, but two or more kinds of polymer primary particles may be used if necessary.

The colorant used here may be an inorganic pigment, an organic pigment, an organic dye, or a combination thereof. Specific examples of these include carbon black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow,
Rhodamine dyes and pigments, chrome yellow, quinacridone,
Any known dyes and pigments such as benzidine yellow, rose bengal, triallylmethane dyes, monoazo dyes, disazo dyes and condensed azo dyes can be used alone or in combination. In the case of a full-color toner, it is preferable to use benzidine yellow as a yellow dye, monoazo dyes and condensed azo dyes and pigments, magenta quinacridone and monoazo dyes and pigments, and cyan as phthalocyanine blue. The colorant is usually used in an amount of 3 to 20 parts by weight with respect to 100 parts by weight of the binder resin.

These colorants are also emulsified in water in the presence of an emulsifier and used in the form of an emulsion, and those having an average particle size of 0.01 to 3 μm are preferably used. As the charge control agent, any known charge control agent can be used alone or in combination. Considering the adaptability of color toner (the charge control agent itself is colorless or pale and does not hinder the color tone of the toner), a quaternary ammonium salt compound is used as the positive charge control agent and a negative charge control agent is used as the negative charge control agent. Metal salts of salicylic acid or alkylsalicylic acid with chromium, zinc, aluminum, etc., metal complexes, metal salts of benzylic acid, metal complexes, amide compounds, phenol compounds, naphthol compounds, phenolamide compounds, 4,4′-methylenebis [2 -[N- (4-chlorophenyl) amide] -3-hydroxynaphthalene]
And the like, such as hydroxynaphthalene compounds are preferable. The amount used may be determined by the desired charge amount of the toner,
Usually 0.01 to 1 per 100 parts by weight of binder resin
The amount used is 0 parts by weight, and more preferably 0.1 to 10 parts by weight.

In the present invention, when the polymer primary particles are obtained,
Using the charge control agent as a seed at the same time as wax,
The charge control agent may be dissolved or dispersed in a monomer or a wax and used, but it is preferred that the charge control agent primary particles are aggregated at the same time as the polymer primary particles to form associated particles to obtain a toner. In this case, the charge control agent is also used in water as an emulsion having an average particle size of 0.01 to 3 μm. The time of addition may be added at the same time in the step of aggregating the polymer primary particles and the colorant primary particles to cause aggregation, or may be added at the stage where these primary particles associate to form a particle aggregate. Alternatively, the particles may be added after the particle aggregate has grown to the final particle diameter of the toner.

In producing the toner of the present invention,
After the particle size of the aggregated particles has grown to substantially the final particle size of the toner, a binder resin emulsion of the same type or a different type is further added and the particles are attached to the surface so that the toner properties in the vicinity of the surface can be improved. It can be modified. Further, the toner of the present invention can be used together with an additive such as a fluidizing agent, if necessary. Specific examples of the fluidizing agent include fine powder of hydrophobic silica, titanium oxide, aluminum oxide and the like. Can usually be mentioned,
It is used in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the binder resin.

Further, in the toner of the present invention, an inorganic fine powder such as magnetite, ferrite, cerium oxide, strontium titanate and conductive titania, a resistance adjusting agent such as styrene resin and acrylic resin, a lubricant and the like are added internally or externally. Used as an additive. The amount of these additives to be used may be appropriately selected depending on the desired performance, and is generally preferably about 0.05 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

The electrostatic image developing toner of the present invention may be used in the form of a two-component developer or a non-magnetic one-component developer. When used as a two-component developer, the carrier may be a magnetic substance such as iron powder, magnetite powder, or ferrite powder, or a known substance such as a resin coated on the surface thereof or a magnetic carrier. As the coating resin for the resin coating carrier, generally known styrene resins, acrylic resins, styrene-acrylic copolymer resins, silicone resins, modified silicone resins, fluororesins, or mixtures thereof can be used.

[0031]

EXAMPLES Next, specific embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited as long as the gist thereof is not exceeded.
The present invention is not limited to the examples below. In the following examples, "parts" means "parts by weight". The average particle size and the molecular weight of the polymer particles were measured by the following methods. Average particle size: Nikkiso Co., Ltd., Microtrac UPA, or Coulter Co., submicron particle analyzer N4
Measured by S. Sphericity: Measured by FPIA2100 manufactured by Sysmex.

Example 1 <Production of Polymer Primary Particles> A glass reactor equipped with a stirrer, a heating / cooling device, a concentrating device, and a raw material / auxiliary charging device was placed in the following emulsifier, demineralized water, and montanic acid. A wax emulsion prepared by emulsifying a mixture of glyceride and behenyl behenate with a nonionic surfactant was charged, and the temperature was raised to 90 ° C. under a nitrogen stream. After that, the following monomers,
An initiator was added and emulsion polymerization was carried out for 7 hours.

[0033]

[Table 1] Wax emulsion (particle size 300 nm) 10 parts Sodium dodecylbenzenesulfonate 0.4 parts Deionized water (including water in wax emulsion) 400 parts [Monomers] Styrene 79 parts Butyl acrylate 21 parts Acrylic acid 3 parts trichlorobromomethane 1 part [crosslinking agent] divinylbenzene 0.2 part [initiator] 8% hydrogen peroxide aqueous solution 10.5 parts 8% ascorbic acid aqueous solution 10.5 parts Cooling after the completion of the polymerization reaction, milky white A coalesced primary particle emulsion was obtained. (Hereinafter, referred to as polymer primary particle dispersion A.) The average particle size of the obtained emulsion was 200 nm, and the weight average molecular weight of the polymer was 160000. <Formation of Associated Particles (Preparation of Toner) and Evaluation>

[0034]

Table 2 Polymer primary particle dispersion A 120 parts (as solid content) Charge control agent Bontron E-82 (5% dispersion) 5 parts (as solid content) Blue dye EP-700BlueGA (manufactured by Dainichiseika Co., Ltd.) Disperse 7 parts or more of the mixture with a disperser while stirring.
Hold at -40 ° C for 2 hours (aggregation step). Then, the pressure inside the polymerization machine containing the coagulation liquid was gradually reduced to 740 mmH.
The defoaming treatment at g was continued for 30 minutes. Then, the temperature was raised to 70 ° C. with stirring and held for 3 hours, and further raised to 95 ° C. and held for 3 hours in order to further increase the bond strength of the associated particles (aging step). After that, the obtained slurry of associated particles was cooled, filtered with a Kiriyama funnel, washed with water, and dried with a blow dryer at 45 ° C. for 10 hours to obtain toner mother particles. The mother particles had a volume average particle size of 7.5 μm and a number average particle size of 6.7 μm, showing a very sharp particle size distribution. The sphericity of this mother particle was 0.96. To the mother particles, 1.2 parts of hydrophobic silica (R972, manufactured by Nippon Aerosil Co., Ltd.) was externally added using a chemical mixer to obtain a test toner. When this toner was put in a commercially available printer (Laserjet 4500, manufactured by Hewlett Packard Co.) and a print test was performed, a very clear image was obtained, and in the life test of 6000 sheets, a slight decrease in density was observed, but it was good. An image was obtained.

Example 2 The same operation was carried out as in Example 1, except that the defoaming treatment operation in forming the associated particles was changed to immediately after the temperature was raised to 70 ° C. in the aging step instead of the aggregation step, and the mother particles for toner were used. Got The mother particles had a volume average particle diameter of 8.3 μm and a number average particle diameter of 6.5 μm, showing a rather broad particle size distribution. The sphericity of this mother particle was 0.98. When the mother particles were subjected to an external additive treatment in the same manner as in Example 1 and a print test was conducted, the image quality was slightly inferior to that in Example 1, but good results of maintaining the initial image quality of 6000 sheets were obtained. .

Comparative Example 1 Test mother particles were obtained by the same procedure as in Example 1 except that the defoaming treatment was not performed. The volume average particle diameter of the mother particles is 8.5 μm, and the number average particle diameter is 6.1 μm, which is a wide particle size distribution. The sphericity of this mother particle is 0.
93, and observing the particles with a scanning electron microscope,
It was a tuft of grapes. When the mother particles were subjected to an external additive treatment in the same manner as in Example 1 and subjected to a print test, the image quality was considerably inferior to that in Example 1, and the density was considerably reduced after 2000 sheets in the life test. It became a poor image. When the toner after the life test is observed with a scanning electron microscope, it is confirmed that silica on the protrusions on the toner surface has disappeared, and it is presumed that the disappearance of this silica caused the image deterioration in the life test.

[0037]

According to the present invention, a toner having excellent image quality and excellent durability can be obtained. The toner of the present invention is
It can be applied to high-resolution printers, copying machines, and the like.

Claims (2)

[Claims] 1. A toner containing at least a resin and a colorant and obtained by an emulsion polymerization aggregation method including at least an emulsion polymerization step, an aggregation step and an aging step, wherein defoaming treatment is performed in the aggregation step and / or the aging step. A toner for developing an electrostatic charge image, which has been received. 2. An emulsion polymerization step in which a monomer mixture containing a monomer having an acidic polar group or a basic polar group is sequentially added to carry out emulsion polymerization, the resulting polymer primary particle dispersion and colorant primary particles and / or Agglomeration step of aggregating primary particles in a mixed solution with a dispersion containing a charge control agent primary particles to form a particle aggregate, and an aging step of heating the dispersion containing the particle agglomerates to cause fusion A method for producing a toner for developing an electrostatic charge image, which comprises performing defoaming treatment in the aggregation step and / or the aging step.