JPH04284461A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To make copying image slight in fogging, excellent in image density and resolution by allowing a associated particle of the primary and the secondary particle of a polymer to have a specific volume resistivity. CONSTITUTION:This toner is constituted of associated particle of the secondary particle containing the primary particle of the polymer having acidic polar group or basic polar group, and a coloring agent particle, and a optional charge control agent, and the volume resistivity thereof is 10<2>-10<3>OMEGAcm in volume resistivity. The primary particle of the polymer having the polar group is a thermoplastic polymer particle having 0.05-0.5mu, preferably 0.1-0.3mu av. particle diameter. The secondary particle is a particle aggregated with the coloring agent particle having 0.01-0.5mu, preferably 0.03-0.1mu av. particle diameter and the primary particle of the polymer having the polar group by ionic bond, hydrogen bond, metal coordinate bond, week electric-week group bond or van der Waal's force. In this case, av. particle diameter is 0.5-5mu, preferably 1-4mu.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to electrophotography, electrostatic recording,
Toner for developing electrostatic images in electrostatic printing, etc.
The present invention particularly relates to a toner characterized by low resistance and a method for producing the same.

0002

[Prior Art] Toner that has been widely used in the past
is a styrene/acrylate copolymer powder obtained by suspension polymerization, dry blended with a coloring agent such as carbon black, an optional charge control agent, and/or a magnetic material, and then melt-kneaded using an extruder or the like. , followed by crushing and classification (Japanese Patent Application Laid-Open No. 51-23354, etc.).

However, the conventional toner obtained by the above-mentioned melt-kneading-pulverization method has a limit in controlling the particle size of the toner, and it is substantially less than 10μ, especially less than 8μ, especially less than 5μ. It has been difficult to produce toner having an average particle size with a good yield.

[0004] Furthermore, in order to lower the resistance (conductivity), toner resistance has been lowered by mixing a conductive substance such as carbon with the toner using a mixer, a ball mill, or the like. Therefore, when used as a developer, the resolution is low and fogging occurs, and if the toner is continuously stirred in the developer, the conductive substance is released from the toner, making it impossible to obtain an image with uniform image density. disadvantages arise.

[0005]

[Problems to be Solved by the Invention] The present invention significantly improves the above-mentioned drawbacks of toners that have been widely used in the past, and also uses a new manufacturing method to produce toners that are less expensive than conventional toners. The purpose of this invention is to provide a toner with a high quality.

[0006]

[Means for Solving the Problems] The present invention provides associated particles of primary particles of a polymer having an acidic polar group or a basic polar group, and secondary particles containing colorant particles and an optional charge control agent. The present invention provides a toner for developing electrostatic images, which has a volume resistivity of 10 2 to 10 8 Ωcm.

[0007] The primary particles of the polymer having a polar group used in the present invention have a particle size of 0.05 to 0.5μ, preferably 0.1 to 0.5μ.
Particles of a thermoplastic polymer having an average particle size of 0.3 microns, which are generally suitably obtained by emulsion polymerization methods.

The secondary particles constituting the above-mentioned associated particles which are the toner of the present invention have a particle size of 0.01 to 0.5, preferably 0.0
The colorant particles having an average particle size of 3 to 0.1μ and the primary particles of the polymer having a polar group form ionic bonds, hydrogen bonds, metal coordination bonds, weak acid-weak group bonds, van der Waals forces, etc. The particles are agglomerated by the bonding force of , and generally have an average particle size of 0.5 to 5 microns, preferably 1 micron to 4 microns.

[0009] The aggregated particles of the present invention are amorphous particles produced by agglomeration of the above-mentioned secondary particles, and the average particle size thereof is generally 3 to 25μ, preferably 5 to 15μ, and most preferably 5 to 13μ. be.

[0010] In a preferred embodiment of the present invention, at least a part of the contact areas between the secondary particles constituting the associated particles, preferably a majority of the contact areas between the secondary particles, are bonded to form a film. particles are used.

The associated particles which are the toner of the present invention contain 20 to 99.9% by weight, preferably 30 to 98% by weight of the polymer having a polar group, based on the total of the polymer having a polar group and the colorant. Most preferably 40-95% by weight and 8% colorant.
It contains 0 to 0.1% by weight, preferably 70 to 2% by weight, and most preferably 60 to 5% by weight.

Preferred examples of the polymer having a polar group used in the present invention are styrenes, alkyl (meth)acrylates, and comonomers having an acidic polar group or basic polar group (hereinafter referred to as ``comonomers having a polar group''). It is a copolymer of

A preferable example of such a copolymer is based on the sum of (a), (a) and (b).
~20% by weight, preferably 70-30% by weight, (b),
10 to 80% by weight, preferably 30 to 70% by weight of alkyl (meth)acrylate based on the total of (a) and (b) and 100 parts by weight of the total of (c), (a) and (b) 0.05 to 30 parts by weight of a comonomer having a polar group,
Preferably 1 to 20 parts by weight

This is a copolymer containing the following. In addition to the monomers (a), (b), and (c), the above copolymer may optionally contain other comonomers that can be copolymerized to the extent that the performance of the toner of the present invention is not impaired. It's okay.

Examples of the styrenes mentioned in (a) above include styrene, o-methylstyrene, m-methylstyrene, and p-methylstyrene.
-Methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p -n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-chloromethylstyrene, etc. Styrene is particularly preferred.

[0016] The alkyl (meth)acrylate of (b) above
Examples include 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, methyl α-chloroacrylate , methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate,

Examples include n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, and stearyl methacrylate, among which carbon atoms having 1 to 12, preferably 3 to (meth)acrylic acid esters of aliphatic alcohols of 8, particularly preferably 4 are used.

Monomer having an acidic polar group (c) above
Examples include (i) α,β-ethylenically unsaturated compounds having a carboxyl group (-COOH) and (ii) α,β-ethylenically unsaturated compounds having a sulfonic group (-SO3H).

Examples of (i) α,β-ethylenically unsaturated compounds having a -COO group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, and maleic acid. Examples include monobutyl ester, monooctyl maleate, and metal salts thereof such as NaZn.

(ii) -SO3H-containing α,β-
Examples of ethylenically unsaturated compounds include sulfonated styrene, its Na salt, allylsulfosuccinic acid, octyl allylsulfosuccinate, and its Na salt.

The comonomer (c) having a basic polar group may be (i) a comonomer having 1 to 12 carbon atoms, preferably 2 carbon atoms, having an amine group or a quaternary ammonium group.
(meth) of an aliphatic alcohol of ~8, particularly preferably 2
(ii) (meth)acrylic acid amide or (meth)acrylic acid amide optionally mono- or di-substituted with an alkyl group having 1 to 18 carbon atoms on N; (iii) N as a ring member; and (iv) N,N-diallyl-alkylamine or its quaternary ammonium salt.

Among these, (i) (meth)acrylic acid ester of an aliphatic alcohol having an amine group or a quaternary ammonium group is preferred as the comonomer having a basic group.

Examples of (i) (meth)acrylic esters of aliphatic alcohols having an amine group or quaternary ammonium group include dimethylaminoethyl acrylate.
dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, quaternary ammonium salt of the above four compounds 3-dimethylaminophenylacrylate, 2-hydroxy-3
-methacryloxypropyltrimethylammonium salt and the like.

(ii) The (meth)acrylic acid amide or (meth)acrylic acid amide optionally substituted with mono- or di-alkyl on N is acrylamide, N-
Butylacrylamide, N,N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N
-butylmethacrylamide, N,N-dimethylacrylamide, N-octadecyl acrylamide, and the like.

Examples of vinyl compounds (iii) substituted with a heterocyclic group having N as a ring member include vinylpyridine, vinylpyrrolidone, vinyl N-methylpyridinium chloride, vinyl N-ethylpyridinium chloride, etc. can be mentioned.

Examples of the N,N-diallylalkylamine (iv) include N,N-diallylmethylammonium chloride and N,N-diallylethylammonium chloride.

The glass transition point of the polar group-containing polymer used in the present invention is -90 to 100°C, preferably -3
0 to 80°C, most preferably -10 to 60°C,
The degree of gelation is 0.0 to 99.9% by weight, preferably 1 to 30% by weight, expressed as insoluble matter during Soxhlet extraction under refluxing acetone. If the glass transition point is too high, exceeding 100°C, low-temperature fixing properties tend to deteriorate, which is undesirable.

Further, if the temperature is too low, such as less than -90°C, the powder fluidity of the toner tends to decrease, which is not preferable. On the other hand, if the degree of gelation is too high, exceeding 50% by weight, the low temperature fixability tends to deteriorate, which is not preferable.

[0029] In this specification, the term "colorant" is used to mean a coloring additive that gives the developer the color necessary for an electrostatic image developer. Additives that impart properties other than colorants to the developer, such as charge control agents and nigrosine dyes, and conductive substances, are also included in the term "colorant" if they impart coloring properties.

As the coloring agent used in the present invention, inorganic pigments, organic pigments and organic dyes are used, preferably inorganic pigments or organic pigments, but one or more pigments and/or one or more pigments are used. Two or more types of dyes may be used in combination as necessary.

[0031] As such inorganic pigments, (a)
Metal powder pigment, (b) Metal oxide pigment, (c)
Carbon pigment, (d) Sulfide pigment, (e)
Chromate pigments, (f) ferrocyanide salt pigments, etc. are suitable.

Examples of such (a) metal powder pigments include zinc powder, iron powder, copper powder, and the like. (b) Examples of metal oxide pigments include magnetite, ferrite, red iron oxide, titanium oxide, zinc white, silica, chromium oxide, ultramarine, cobalt blue, cerulean blue, mineral violet, trilead tetroxide, etc. can be mentioned.

(c) Carbon pigments include carbon black, thermatic carbon, lamp black, furnace black, and the like. (d) Sulfide pigments include zinc sulfide, cadmium red, selenium red, mercury sulfide, cadmium yellow, and the like.

(e) Chromate pigments include molybdenum red, barium yellow, and strontium yellow.
, chrome yellow, etc. (f) Examples of the ferrocyanide compound pigment include Milolibru.

[0035] Examples of the above-mentioned organic pigments include the following. (a) Azo pigments: Hanzai Elo-G, Benzidine Yellow, Benzidine Orange, Permanent Red 4
R, Pyrazolone Red, Resol Red, Virilliant Scarlet G, Bonmaren Light, etc.

(b) Acidic dye pigments and basic dye pigments, Olenzo II, Acit Orange R, Eoxin, Quinoline Yellow, Tartrazine Yellow, Acid Green
Dyes such as peacock blue, peacock blue, and alkaline blue are precipitated using a precipitant. Rhodamine, magenta, malachite green, methyl violet, Victoria blue
Dyes such as tannic acid, tartarite, PTA, PMA, PT
Such as those precipitated by MA etc.

(c) Mordant dye pigments, metal salts of hydroxyanthraquinones, alizarin marder lake, etc. (d) Phthalocyanine pigments phthalocyanine blue, sulfonated copper phthalocyanine, etc.

(e) Quinacridone pigments and dioxane pigments Quinacridone Red, Quinacridone Violet, Carbazole Dioxazine Violet, etc. (f) Others

Organic fluorescent pigments, aniline black, etc. Further, as the organic dye, nigrosine dye and aniline dye are used.

As described above, the toner of the present invention contains a charge control agent, a magnetic material, etc., if necessary. Such charge control agents include nigrosine-based electron-donating dyes for positive use, metal salts of naphthenic acids or higher fatty acids, alkoxylated amines, quaternary ammonium salts, alkylamides, chelates, pigments, and fluorine treatment. activators, etc.

Electron-accepting organic complex for negative use,
Other examples include chlorinated paraffin, chlorinated polyester, polyester with excess acid groups, and sulfonylamine of copper phthalocyanine.

As the conductive substance used in the present invention, a carbon pigment or a conductive titanium oxide is used, but one or more conductive substances may be used in combination as necessary. Examples of such carbon pigments include carbon black, thermatomic carbon, lamp black, and furnace black, but carbon black with a DBP oil absorption of 100 ml/100 g or more is preferable. It is.

Examples of the conductive titanium oxide include anatase type conductive titanium oxide, rutile type conductive titanium oxide, and transparent conductive titanium oxide.

[0044] The amount of the carbon-based application material and the conductive substance such as conductive titanium oxide used is 0.1 to 30% by weight, preferably 1 to 28% by weight, particularly preferably 2 to 2% by weight, based on the toner.
5% by weight, more preferably 5 to 22% by weight.

Furthermore, it is preferable to add the conductive substance in two stages: when the primary particles are generated and when or after the secondary particles are generated, since the total amount of the conductive substance to be used can be reduced.

[0046] The amount of the conductive substance used when generating the primary particles is preferably 1 to 20% by weight, particularly preferably 3 to 15% by weight, based on the toner.

The amount of the conductive substance used during or after the generation of the associated secondary particles is preferably 0.1 to 20% by weight, particularly preferably 1 to 18% by weight, based on the toner.
, more preferably 3 to 15% by weight.

Further, the toner of the present invention can be used together with additives such as a fluidizing agent, if necessary, and examples of such fluidizing agents include fine powders such as hydrophobic silica, titanium oxide, and aluminum oxide. It is used in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 1 part by weight per 100 parts by weight of toner.

A preferred method for producing the toner of the present invention is as follows. A required amount of colorant powder and an optional charge control agent are added and mixed to an emulsion of a polymer having an acidic polar group or a basic polar group obtained by emulsion polymerization, and the mixture is uniformly dispersed for 0.5 to 4 hours, preferably. When stirring is continued for 1 to 3 hours, the primary particles of the polymer having polar groups and the colorant particles gradually aggregate to form secondary particles having an average particle size of 0.5 to 5 .mu.m.

[0050] Such a dispersion is further diluted as it is from 0.5 to
If the stirring is continued for 3 hours, preferably 1 to 2 hours, the secondary particles will further aggregate and grow into associated particles having an average particle size of 5 to 25 microns.

In the most preferred method for producing the toner of the present invention, the dispersion liquid thus produced is further heated to a temperature of 1 to 65°C higher than the glass transition point of the polymer having a polar group. When stirring is continued for a period of time, preferably from 2 to 4 hours, associated particles in which at least a portion of the contact areas between the secondary particles are fused to form a film are produced.

[0052] Since such associated particles have a film-forming fusion bond between the secondary particles, they hardly disintegrate during storage, transportation, developer manufacturing, etc., and are therefore suitable for use as a developer for developing electrostatic images. It is particularly suitable as

An electrically conductive substance is added to the dispersion of the associated particles and adsorbed onto the surface of the associated particles.The electrically conductive substance may be added in the form of a powder, but it is preferable to add 1.0% of the electrically conductive substance in water in advance.
It is preferable that the particles be dispersed to an average particle diameter of 0 μm or less.

Further, by continuing stirring at a temperature between the glass transition point of the polymer having a polar group and 65° C. higher than the glass transition point for 1 to 6 hours, preferably 2 to 4 hours, the conductive substance is completely coated on the surface of the associated particles. Fixed.

[0055] Due to this, when used as a developer, the toner
Even if the toner is continuously stirred in the developing device, the conductive substance is not released from the toner.

The toner of the present invention is mixed with a carrier such as iron or glass beads to form a developer, but if the toner itself already contains ferrite or the like as a coloring agent, ferrite or the like may be added. Since the toner also acts as a carrier, in that case the toner can be used as it is as a developer.

[0057] In the present invention, the volume resistivity is 102 to 1
08 Ωcm, preferably 104 to 107 Ωcm, particularly preferably 105 to 107 Ωcm, and the volume resistivity is 10
If it is more than 8 Ωcm, various physical properties such as image density and resolution will deteriorate, and if it is too little than 102 Ωcm, fog density,
Physical properties such as resolution deteriorate.

The present invention will be specifically explained below with reference to Examples. Note that unless otherwise specified, quantities are expressed by weight.

[0059]

[Example 1] Preparation of acidic polar group-containing polymer resin Styrene monomer (ST) 60 parts Butyl acrylate (BA)
40 parts acrylic acid (AA)
8 parts or more of the monomer mixture in water
100 parts nonionic emulsifier (Emulgen 950) 1 part anionic emulsifier (Neogen R) 1.5 parts potassium persulfate
It was added to 0.5 part of an aqueous solution mixture and polymerized at 70° C. for 8 hours with stirring to obtain an acidic polar group-containing resin emulsion with a solid content of 50%.

Preparation of toner (1) Acidic polar group-containing resin emulsion
90 parts magnetite (MG-WS manufactured by Mitsui Kinzoku) 50 parts carbon black (Regal 330R manufactured by Cabot)
5 parts water

230 copies

The above mixture was maintained at about 30° C. for 2 hours while being dispersed and stirred using a slasher. after that,
The mixture was further heated to 70° C. with stirring and maintained for 3 hours. During this time, it was observed through a microscope that a complex of resin particles and magnetite particles had grown to about 10 μm in size.

[0062] 5 parts of carbon black (Vulcan XC72, manufactured by Cabot) was added to the aggregate particles, and
It was further heated to 90°C and held for 2 hours. After cooling, the resulting liquid dispersion was filtered through a Buchner filter and vacuum dried at 50°C for 10 hours.

Silica (Aerosil R97 manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts by weight of the obtained toner as a fluidizing agent.
2) was added and mixed to prepare a test developer. The above polymer used in this toner has a Tg of 45°C, a degree of gelation of 5%, a softening point of 148°C, and an average particle size of the toner.
It was 12μ.

Further, the volume resistivity of this toner was measured and found to be 5×10 6 Ωcm. The volume resistivity was measured using an insulation resistance measuring device (manufactured by Takeda Riken Co., Ltd.) after toner particles were molded using a hydraulic press at a pressure of 200 kg/cm 2 .

When the above-mentioned toner was placed in a copying machine using a conductive magnetic brush developing device and copies were made, copies with high density and little fogging were obtained. The results are shown in Table 1.

[0066]

Example 2 After preparing the same acidic polar group-containing resin emulsion as in Example 1, the following operations were carried out during toner preparation. Adjustment of toner (2) Acidic polar group-containing resin emulsion
80 parts magnetite (Mitsui Kinzoku Co., Ltd. MG
-WS) 50 parts carbon crack (Mitsubishi Kasei MA-100) 10 parts water

230 copies

To this, 10 parts of conductive titanium oxide (ECT-52 manufactured by Titan Kogyo Co., Ltd.) was added based on the associated particles, and the above mixture was subjected to the same operation as in Example 1 to prepare a test toner. did. The obtained polymer had a Tg of 43°C, a degree of gelation of 590, a softening point of 147°C, and an average particle size of the toner of 10.5 μm. The volume resistivity of the toner was 6×10 4 Ωcm. A copying experiment similar to that in Example 1 was conducted, and good results similar to those in Example 1 were obtained. The results are shown in Table 1.

[0068]

[Comparative Example 1] Same formulation as Example 1, average particle size 10.0
The resulting liquid dispersion was grown into μm-sized associated particles and cooled, followed by Buchner filtering and vacuum drying at 50° C. for 10 hours. The volume resistivity of this toner was measured and was 4 x 109Ω.
cm, and when a similar copying test was conducted, only images with very low image density were obtained. The results are shown in Table 1.

[0069]

[Comparative Example 2] Carbon black (Vulcan
10 parts of 2) were added to the toner, and the mixture was stirred with a ball mill or the like to adhere to the toner surface.

The volume resistivity of this toner is 50Ωcm
Met. When a copying test similar to that in Example 1 was carried out, the resulting image had a very large amount of fog, and furthermore, the toner was removed in the developing device.
When images were continued to be produced while stirring was continued, scumming appeared on the images, which was thought to be due to release of carbon. The results are shown in Table 1.

[0071]

[Table 1]

Copied image resolution evaluation method: Copy the Datakwest test pattern AR-4,
The resolution was evaluated by visually checking the number of lines per 1 mm. In this evaluation method, with the resin composition shown in Table 1, a resolution of 6.3 or higher can be judged as good, and a resolution of 3.6 or less can be judged as bad.

Copy image fog evaluation method: Using a CM-53P reflectance meter manufactured by Murakami Color Laboratory Co., Ltd., the reflectance of blank paper before copying and the reflectance of non-text portions after copying were measured at a light angle of 45°. The fog density (%) was calculated based on the reflectance ratio. Good fog with fog density below 0.7,
If it is 1.0 or more, it can be determined to be defective.

Image Density Evaluation Method Using a Macbeth reflection densitometer RD-914, the density of a solid black image was measured. An image density of 1.2 or more can be judged as good, and an image density of 1.0 or less can be judged as bad.

Measurement of Particle Size Measurement was carried out in a conventional manner using a Coulter Counter (Coulter Multisizer) manufactured by Coulter.

[0076]

[Effects of the Invention] The present invention provides a toner for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc., which has less fog in copied images and has excellent image density and resolution, and a method for producing the same. It is something to do.

Claims (6)

[Claims] 1. Associated particles of primary particles of a polymer having an acidic polar group or basic polar group, and secondary particles containing colorant particles and an optional charge control agent, the particles having a volume resistivity of 102 to 1. An electrostatic image developing toner characterized by having a resistance of 108 Ωcm. 2. The toner for developing an electrostatic image according to claim 1, wherein the associated particles have an outer layer of a conductive substance on the surface thereof. 3. The toner for developing electrostatic images according to claim 1, wherein the conductive substance is a carbon pigment or conductive titanium oxide. 4. The toner for developing electrostatic images according to claim 1, wherein the carbon pigment or conductive titanium oxide is present in an amount of 0.1 to 30% by weight based on the toner.
. 5. The toner according to claim 1, wherein at least a portion of the contact area between the secondary particles is fused to form a film. 6. A colorant and an optional charge control agent are added to the polymer emulsion, heated at 20 to 45°C for 1 to 3 hours with stirring, and then heated to a temperature between the glass transition point of the polymer and 65°C higher than the glass transition point. of a polymer having an acidic polar group or a basic polar group, which is characterized by adsorbing a conductive substance to the generated associated particles by heating with stirring for 1 to 3 hours, and then drying the bound particles. A method for producing a toner for developing an electrostatic image, wherein the volume resistivity of associated particles of secondary particles containing primary particles, colorant particles, and an optional charge control agent is 102 to 108 Ωcm.