JPH07104509A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain a toner having a small change in electrostatic charge by the environment, high definition and high color reproducibility by using specified polyester resin as a base and incorporating di- or higher valent counter cations. CONSTITUTION:This toner is based on polyester resin having 2-30mum average particle diameter (D) and particle diameter distribution in which >=80wt.% of all the particles exist in the particle diameter range of 0.5D to 2.0D. The polyester resin in chiefly obtd. by condensing polycarboxylic acids with polyols and contains 20-1,000eq./ton anionic groups. Counter cations accounting for >=30% of all counter cations to total ionic groups are di- or higher valent cations. The environmental stability of the extent of electrostatic charge is improved, the absolute value of the extent of electrostatic charge lowers and satisfactory image characteristics, fixing characteristics and blocking resistance besides the improved environmental stability can be ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used as a developer in electrophotographic copying machines, laser printers, facsimiles and the like.

[0002]

2. Description of the Related Art Generally, the electrophotographic method is a photoconductive material of inorganic type such as selenium, amorphous silicon, zinc oxide or the like, or organic type such as diazo compound or dye (often processed into a drum shape). (: Photosensitive drum) is uniformly charged, then an electrostatic latent image is formed by irradiating the image-modulated light, and the electrostatic latent image is developed by adhering powder by electrostatic force. Then, the powder is transferred onto a base material such as paper or film, if necessary, and then fixed by a method such as pressing or heating. The electrophotographic system is currently widely used in copiers, laser printers, facsimiles and the like.

A powder that develops an electrostatic latent image on a photosensitive drum in an electrophotographic system and is finally transferred to a base material such as paper or film to form an image is called a toner. These toners are usually mixed with carrier particles (: carrier) such as glass beads, iron powder, and ferrite, and used as a so-called developer. As a toner used in a developer for electrophotography, a colorant, a charge control agent, a fluidity modifier, a pulverization auxiliary agent, etc. are added to a binder resin, and the mixture is kneaded and then pulverized.
Particles produced by a so-called pulverization method for further classification are used. Styrene / acrylic resin is mainly used as the binder resin. In recent years, with the increase in definition and color of electrophotographic images, miniaturization and colorization of toner have been promoted. According to the conventional pulverization / classification method, it is pointed out that there is a limit to the fineness of the toner particle size in terms of pulverization efficiency, yield, etc., and it is also very difficult to narrow the particle size distribution by the air flow classification method. Has been done. Therefore, particles obtained by "polymerization granulation method" such as emulsion polymerization method, suspension polymerization method, seed polymerization method, dispersion polymerization method, etc.
Has been proposed for use. On the other hand, in color images, the gloss of the image surface is required from the viewpoint of color reproducibility, and further, the polyester excellent in low-temperature fixability is required due to the demand for high-speed image output and energy saving (low fixing temperature). Resins have attracted attention as binder resins for toners. Conventionally used polyester resins are mainly unsaturated polyester resins obtained by polycondensation of aliphatic unsaturated carboxylic acids such as fumaric acid and maleic acid with dioles having a bisphenol structure. Conventional toner using unsaturated polyester resin
Has poor chemical stability because it has an unsaturated bond,
In addition, plasticizers used in vinyl chloride resin, eraser, etc. easily migrate, so copy images are stored in transparent files, sandwiched between desk mats, left with eraser or left with eraser residue attached. In this case, there is a problem that the image is damaged or the transparent sheet and the eraser are contaminated due to the influence of vinyl chloride or the plasticizer contained in the eraser. Further, these unsaturated polyester resins have a high acid value due to their production method, and have a drawback that the charging characteristics and fixing characteristics become unstable due to moisture absorption. It is desirable to use a dye as a coloring material to be used for colorizing the toner from the viewpoint of transparency, high saturation, etc., but when the unsaturated polyester resin described here is used as the binder resin, the dye is used. Is poorly compatible with, and particularly, the light fastness is significantly impaired. Therefore, pigments are unavoidably used. However, few of the existing pigments are desirable in terms of color tone, they are expensive, and much labor is required to disperse the pigment in order to ensure transparency to a certain extent or more.

On the other hand, the resin particles obtained by the emulsion polymerization method and the suspension polymerization method have a limited particle size range,
In addition, the particle size distribution can only be broad. See
Resin particles obtained by the depolymerization method and the dispersion polymerization method,
Although it has a sharp particle size distribution, it is very expensive. Further, the above-mentioned "polymerization granulation method", that is, the resin particles produced by emulsion polymerization, suspension polymerization, seed polymerization, and dispersion polymerization are, as is obvious from the production method, a vinyl-based polymer. Limited to resin particles. Vinyl-based polymers, specifically, styrene / acrylic copolymer-based resins have a problem that the plasticizers used in vinyl chloride-based resins, erasers, etc. are apt to migrate, like the unsaturated polyester resins described above. , Because the solubility of the dye is low, high-density coloring cannot be performed, and the surface gloss of the obtained image is poor, resulting in poor color reproduction.
It is not possible to obtain satisfactory particles as a toner.

As described above, that is, a fine and narrow particle size distribution powder of a colored polyester resin is preferable as an electrophotographic toner for reproducing a high-definition color image. The reality is that no method has yet been proposed to produce it economically. In view of such circumstances, the present inventors have conducted research to realize a powder having a polyester resin as a main component and having a fine and narrow particle size distribution, and as a result, have an arbitrary average particle size and a sharp particle size. JP-A-3-212444 has been proposed as a material having a distribution and capable of industrially producing resin particles in a polyester resin which is a condensation polymer. According to the invention, the polyester resin contains a predetermined amount of ionic groups, and after the polyester resin is microdispersed in an aqueous medium, the dispersion stability of the microdispersion in water is controlled to allow slow agglomeration to give an arbitrary particle diameter, It is intended to obtain substantially spherical polyester particles having a sharp particle size distribution. Such polyester particles can be easily colored with a dye, and / or a pigment, carbon black, etc., and the properties required as a toner binder resin can be satisfied by adjusting the copolymerization composition. Since it is substantially spherical, it has excellent fluidity and uniform triboelectrification.

[0006]

However, according to the subsequent research, although the particles obtained in the above-mentioned invention have a low acid value, the charging characteristics are easily affected by the temperature and humidity of the environment, and the image density It has become clear that environmental stability is insufficient. The present inventors have further earnestly studied to realize excellent polyester particles as a toner, and have reached the next invention.

[0007]

In view of the above situation, the inventors of the present invention have earnestly studied to obtain an electrophotographic toner having excellent environmental stability, and have arrived at the next invention. That is, the present invention has an average particle diameter D of 2 to 30 μm, has a particle diameter distribution in which 80 wt% or more of all particles are present in the particle diameter range of 0.5 D to 2.0 D, and is mainly composed of polyvalent carboxylic acids. A polyester resin obtained by condensation of polyhydric alcohols and having an anionic ionic group of 20 to 1000 eq./ton as a main component, and counter cations of 30% or more of the total number of ionic groups are contained. An electrophotographic toner characterized by being a cation having a valence of 2 or more.

The electrophotographic toner of the present invention has a volume average diameter D
Is essential to be in the range of 2 to 30 μm, and 3-1
A range of 5 μm is preferred, a range of 3-10 μm is more preferred, a range of 3-8 μm is more preferred, and a range of 4-7 μm is even more preferred. If the volume average diameter is less than this range, it becomes difficult to handle particles, and if it exceeds this range, there may be a problem in image reproducibility. Regarding the particle size distribution of the particles of the present invention, it is essential that particles having a particle size in the range of 0.5D to 2.0D occupy 80 wt% or more of the whole, preferably 85 wt% or more, further 90 wt% or more, Furthermore 9
It is preferable to occupy 5 wt% or more. According to another expression, the particle size range occupied by 70 wt% or more is from 0.6D to
A range of 1.8D is preferable, and 0.7D to 1.5D is more preferable.
The range of 0.8D to 1.3D,
Furthermore, it is preferable that it is in the range of 0.9D to 1.2D. The coefficient of variation, which is the value obtained by dividing the standard deviation by the average value, is preferably 30% or less, more preferably 20% or less, still more preferably 15% or less, and further preferably 10% or less. . Particles having such an average particle size and particle size distribution can be realized by the method described below.

The toner of the present invention contains a polyester resin as a main component. The polyester resin is preferably used in an amount of 50 wt% or more of the total resin component, more preferably 80 wt% or more,
Further, it is preferable that the content is 90 wt% or more, 95 wt% or more, and further 98 wt% or more. The polyester resin in the present invention is mainly composed of polyvalent carboxylic acids and polyvalent alcohols. Examples of the polyvalent carboxylic acids used for the polyester resin include: terephthalic acid, isophthalic acid, orthophthalic acid, 1,
5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, anthracene dipropionic acid, anthracene dicarboxylic acid, diphenic acid, sulfoterephthalic acid, 5
-Sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7dicarboxylic acid, 5 [4-sulfophenoxy] isophthalic acid, sulfoterephthalic acid, and / or aromatic dicarboxylic acids such as metal salts and ammonium salts thereof. Aromatic oxycarboxylic acids such as p-oxybenzoic acid and p- (hydroxyethoxy) benzoic acid, succinic acid, adipic acid, azelaic acid, sebacic acid,
Aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, aliphatic unsaturated polycarboxylic acids such as fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, and aromatic unsaturated polycarboxylic acids such as phenylenediacrylic acid Carboxylic acids-Alicyclic dicarboxylic acids such as hexahydrophthalic acid and tetrahydrophthalic acid-Trivalent or higher polycarboxylic acids such as trimellitic acid, trimesic acid and pyromellitic acid

In the present invention, a part of the polycarboxylic acids may be used together with the monocarboxylic acids. Aromatic monocarboxylic acids are preferred as the monocarboxylic acids. Examples of the aromatic monocarboxylic acid include benzoic acid, chlorobenzoic acid, bromobenzoic acid, parahydroxybenzoic acid, naphthalenecarboxylic acid, anthracenecarboxylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, salicylic acid, thiosalicylic acid, phenyl. Acetic acid and lower alkyl esters thereof, sulfobenzoic acid monoammonium salt, sulfobenzoic acid monosodium salt, cyclohexylaminocarbonylbenzoic acid, n-dodecylaminocarbonylbenzoic acid, tert-butyl benzoic acid, tert-butylnaphthalenecarboxylic acid Etc. can be used, and especially
It is more preferred to use charbutyl benzoic acid.
The amount of the aromatic monocarboxylic acid used is 2 to the acid component.
25mol%, 5-20mol%, 8-16mo
The use of l% is more preferred. In the present invention, preferably 70 mol% or more, more preferably 80 mol% or more, and further 90 mol% or more of the polyvalent carboxylic acids are aromatic polycarboxylic acids. In the present invention, 40-95 mol% of terephthalic acid and 5-60 isophthalic acid are used as polycarboxylic acids.
mol%, and the sum of terephthalic acid and isophthalic acid is 80
It is preferably at least mol%. The content of terephthalic acid is preferably 60 to 95 mol%, more preferably 70 to 90 mol%, and the sum of terephthalic acid and isophthalic acid is 90 mol%.
The above is more preferable. When the content of terephthalic acid is less than the above range, the quality of the copied image may be impaired by the plasticizer contained in the eraser, vinyl chloride and the like. Also, as a polycarboxylic acid, trimellitic acid,
It is preferable to contain 0.5 to 8 mol% of a trivalent or higher polyvalent carboxylic acid such as trimesic acid and pyromellitic acid.

Examples of the polyvalent alcohols used for the polyester resin include aliphatic polyvalent alcohols, alicyclic polyvalent alcohols, aromatic polyvalent alcohols and the like. As the aliphatic polyhydric alcohols, ethylene glycol
, Propylene glycol, 1,3-propanedioe
2,3-butanediol, 1,4-butanediol
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol
, Dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, polyethylene glycol
Examples include aliphatic diols such as propylene, polypropylene glycol and polytetramethylene glycol, triols such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and tetraols. it can. .As the alicyclic polyvalent alcohols, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol,
Spiroglycol, hydrogenated bisphenol A, ethylene oxide adduct of hydrogenated bisphenol A and propylene oxide adduct, tricyclodecanediol,
Examples thereof include tricyclodecane dimethanol.

As the aromatic polyhydric alcohols, para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol,
Examples thereof include ethylene oxide adducts of 1,4-phenylene glycol, bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts. Further, as the polyester polyol, lactone type polyester polyols obtained by ring-opening polymerization of lactones such as ε-caprolactone can be exemplified. Further, like the carboxylic acids, monoalcohols such as aliphatic alcohols, aromatic alcohols and alicyclic alcohols can be used. In the present invention, the polyvalent alcohol is preferably 70 mol% or more, further 80 mol% or more, and further 9
It is desirable to use 0 mol% or more of aliphatic diols and / or alicyclic diols. As the aliphatic diols, it is preferable to use ethylene glycol, propylene glycol or 2,3-butanediol. As the alicyclic diols, it is preferable to use tricyclodecane dimethanol, cyclohexane diol, or cyclohexane dimethanol. In the present invention, the content of ethylene glycol and / or propylene glycol as polyhydric alcohols is 50 mol% or more, further 60 mol% or more, and further 70
It is preferably mol% or more.

More specific examples of the main component of the polyester resin in the present invention include (1) a) polyvalent carboxylic acids containing 80 mol% or more of an aromatic monomer, and b) ethylene glycol 0. To 90 mol% and 100 to 10 mol% of propylene glycol, (2) a) polyvalent carboxylic acids containing 80 mol% or more of an aromatic monomer, and b) 2,3-butanedio- Polyester resin obtained from 5 to 80 mol% of ethylene glycol and 20 to 95 mol% of ethylene glycol (3) a) polyvalent carboxylic acids containing 80 mol% or more of an aromatic monomer, and b) C2 to C4 Polyester resin obtained from aliphatic glycols 70 to 95 mol% and c) mono and / or polyvalent alcohol having tricyclodecane skeleton 5 to 30 mol% (4) a) Aromatic monomer Polyvalent carboxylic acids containing 80 mol% or more of bodily compounds, and b) C2 to C4 Polyester resin obtained from 70 to 95 mol% of aliphatic glycols of c) and 5 to 30 mol% of c) hydroxymethyltricyclodecane (5) a) Polyvalent carboxylic acid containing 80 mol% or more of aromatic monomer Polyester resin obtained from acids, b) C2 to C4 aliphatic glycols 70 to 95 mol% and c) tricyclodecane dimethanol 5 to 30 mol% (6) a) aromatic monomer Polyvalent carboxylic acids containing 80 mol% or more of a monomer, b) 70 to 95 mol% of C2 to C4 aliphatic glycols, and c) mono and / or polyvalent alcohol having a cyclohexane skeleton.
Polyester resin (7) a) containing 80 mol% or more of an aromatic monomer, and b) a C2 to C4 aliphatic glycol 70 -95 mol%, c) a polyester resin obtained from 5 to 30 mol% of cyclohexanediol (8) a) a polycarboxylic acid containing 80 mol% or more of an aromatic monomer, and b) a C2 to C4 Polyester resin obtained from 70 to 95 mol% of aliphatic glycols, c) 5 to 30 mol% of hydrogenated biphenol (9) a) Polycarboxylic acid containing 80 mol% or more of aromatic monomer , And b) C2 to C4 aliphatic glycols 70 to 95 mol% and c) hydrogenated bisphenol A 5 to 30 mol% polyester resin (10) a) monoand / having a naphthalene skeleton or 80 mol% of aromatic monomer containing 1 to 20 mol% of divalent or higher carboxylic acid
B) C2 to C4 aliphatic glycols containing 70 to 100 mol of the above-mentioned polyvalent carboxylic acids
%, C) Polyvalent alcohol containing 0 to 30 mol% of alicyclic monomer
Examples thereof include polyester resins obtained from and the like.

The glass transition point of the polyester resin in the present invention is 55 ° C. or higher, preferably 60 ° C. or higher, more preferably 63 ° C. or higher, and even more preferably 65 ° C. or higher. If the glass transition point is lower than this, blocking tends to occur during handling or storage, which may cause storage stability problems. The softening point of the polyester resin in the present invention is in the range of 80 to 150 ° C. In a toner having a resin softening temperature lower than this, there is a tendency for the toner to aggregate during handling or storage, and the fluidity may be greatly deteriorated particularly during long-term storage. If the softening point is higher than this, the fixability is impaired. Further, since it is necessary to heat the fixing roll to a high temperature, the material of the fixing roll and the material of the substrate to be copied are limited. Although the polyester resin in the present invention permits the use of a trivalent or higher polyvalent carboxylic acid component and / or a combination of trivalent or higher polyvalent alcohols,
The purpose is to broaden the molecular weight distribution of the polyester resin, not to gel the resin. The gelation of the resin makes it particularly difficult to take out the resin from the polyester polymerization apparatus, resulting in a marked decrease in productivity. In the present invention, there is substantially no gelation, and more specifically, the chloroform insoluble content is 0.5% by weight or less, preferably 0.25.
It should be less than or equal to wt%. The acid value of the polyester resin in the present invention is preferably 3 mgKOH / g or less, more preferably 12 mgKOH / g, and further preferably adjusted not to exceed 0.5 mgKOH / g.

The polyester resin of the present invention has a specific gravity of 1.3.
It is preferably not less than 1.31, more preferably not less than 1.31, and even more preferably not less than 1.32. Further, the polyester resin of the present invention preferably does not dissolve in a single solvent such as methyl ethyl ketone and toluene or tetrahydrofuran at room temperature. If the specific gravity and the solubility in a solvent are low, the PVC plasticizer resistance may decrease. The solubility in a solvent can be adjusted mainly by the copolymerization ratio of terephthalic acid and isophthalic acid or the composition ratio of alicyclic polyvalent alcohol and aliphatic polyvalent alcohol. In the present invention, it is essential that the polyester resin contains an anionic ionic group in the range of 20 to 1000 eq./ton.
The content of the ionic group is 10 to 1000 meq / 100
0 g is preferable, and further 20 to 500 meq / 1000
g, more preferably 50 to 200 meq / 1000 g. As the ionic group, a sulfonic acid alkali metal salt group, and / or a sulfonic acid ammonium salt group, and / or a carboxylic acid alkali metal base, and / or a carboxylic acid ammonium salt group, a sulfuric acid group, a phosphoric acid group, a phosphonic acid group, A phosphinic acid group or an ammonium salt or metal salt thereof can be used. In the present invention, the aromatic monomer is a sulfonic acid alkali metal base.
and / or Mono and / or with ammonium sulfonate base
By containing 0.1 to 6.0 mol% of dicarboxylic acid, an ionic group can be introduced into the polyester resin. When introducing a carboxylate alkali metal base and / or a carboxylate ammonium base, a carboxyl group is added to the polymer terminal by introducing a polyvalent carboxylic acid such as trimellitic acid into the system at the final stage of polymerization of polyester. ,
Furthermore, a method of exchanging it with a carboxylate group by neutralizing it with ammonia, sodium hydroxide or the like can be used. Such an ionic group has a function of imparting water dispersibility described below to the polyester resin, but when the counter-cation is a polyvalent ion, the water dispersibility cannot be sufficiently expressed. Therefore, the counter cation of these ionic group-containing monomers during the polymerization of polyester is usually a monovalent cation. In the present invention, it is essential that 30% or more of the total number of such ionic groups are cations having a valence of 2 or more, but for the above reason, ion exchange by post-treatment is necessary.

A method for obtaining particles having an average particle size and particle size distribution according to the present invention from the anionic group-containing polyester resin of the present invention will be described below. The ionic group-containing polyester resin exhibits water dispersibility. The aqueous fine dispersion of the ionic group-containing polyester resin of the present invention can be produced by any known method. That is, the ionic group-containing polyester resin and the water-soluble organic compound
It is produced by mixing in advance at 0 to 200 ° C. and adding water thereto, or adding a mixture of an ionic group-containing polyester resin and a water-soluble organic compound to water and stirring at 40 to 120 ° C. Alternatively, it is also produced by a method in which an ionic group-containing polyester resin is added to a mixed solution of water and a water-soluble organic compound and dispersed by stirring at 40 to 100 ° C. As the water-soluble organic compound, ethanol, butanol, isopropanol, ethyl cellosolve, butyl cellosolve, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, etc. can be used. It is not preferable to use a surfactant together,
The use is not particularly limited. The average particle size of the water-based fine dispersion thus obtained is generally 0.01 to 1.0.
It is about μm.

By the action of the electric double layer resulting from the dissociation of the ionic groups contained in the polyester resin, the fine particles of the ionic group-containing polyester resin are finely dispersed in the aqueous medium. This means a state of being present, and is generally called an emulsion or colloidal dispersion. The stability of such finely dispersed particles is D.
As described in the LVO theory, the surface potential of particles (practically, zeta potential) depends on the maximum value VT of the potential curve obtained from the electrolyte concentration in the dispersion system. V
T is obtained by the following equation VT (h) = VR + VA = (εaψ 2/2) ln {1 + exp (-κh)} -
(A · a / 12 · h) where ε: dielectric constant a: particle diameter ψ: surface potential h: interparticle distance A: Hammer-Marker constant 1 / κ: electric double layer thickness κ = (8πnZ ² e ² / εkT) ^1/2 n: Electrolyte concentration Z: Ion valency e: Elementary charge k: Boltzmann constant T: Absolute temperature VT is compared with energy due to thermal motion-kT (product of Boltzmann constant and absolute temperature) If it is sufficiently large, it is called a stable dispersion region, and the finely dispersed particles maintain a stable dispersed state for a long time. When VT is at the same level as or lower than kT, it is called a rapid aggregation region, and finely dispersed particles are rapidly aggregated and settled. The state where VT is in the intermediate state between the stable dispersion region and the rapid aggregation region is called the "slow aggregation region".

In the slow aggregation region, the aggregation of particles proceeds very slowly. When a sufficiently long time has elapsed, the finely dispersed particles eventually aggregate and settle as in the rapid aggregation region. However, when the finely dispersed particles are plasticized in the slow agglomeration region, the agglomerated particles aggregate and become spherical due to surface tension, and grow into new particles with a larger particle diameter (larger curvature). . D.L.
Since VT described in the V.O. theory is directly proportional to the particle size, particle growth in the region where VT is positive (increased particle size)
Will increase the stability of the particles. As a result, if the system is introduced into the slow agglomeration region in the plasticized state of the particles, the particles will grow slowly and eventually reach the stable region and re-stabilize. In the rapid aggregation region, the aggregation speed is faster than the time required for aggregation and spheroidization, so aggregation progresses based on VT obtained from the part with the smallest curvature of the aggregates of multiple particles, and the aggregates are disordered like dendrites. It is not possible to grow stable particles. It is difficult to define the slow aggregation region by the value of VT, but it is in the practical range (from several minutes to
The range in which the polyester resin particles can be produced in a few hours to a few days) is in the range of 3 kT <VT <30 kT. The zeta potential of the finely dispersed particles is 20 mV to 70 mV, and further 20 mV to before the addition of the electrolyte.
It is preferable to control to 60 mV, or even 25 mV to 50 mV. Polyester resin particles are introduced into an aqueous microdispersion of an ionic group-containing polyester resin by adding an electrolyte to the aqueous microdispersion of the ionic group-containing polyester resin under conditions in which the ionic group-containing polyester resin is plasticized, thereby leading the finely dispersed particles to a slow aggregation region It can be obtained by growing particles. At this time, an operation of lowering the zeta potential may be used together.

As the electrolyte used in the present invention, sodium sulfate, ammonium sulfate, potassium sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, ammonium chloride, calcium chloride, cobalt chloride, strontium chloride. , General inorganic or organic water-soluble salts such as cesium chloride, barium chloride, nickel chloride, magnesium chloride, rubidium chloride, sodium chloride, potassium chloride, sodium acetate, ammonium acetate, potassium acetate, sodium benzoate, etc. Can be used. The concentration of these electrolytes is 0.01 when a monovalent electrolyte is used.
The range of -2.0 mol / l, more preferably 0.1-1.0 mol / l, and even more preferably 0.2-0.8 mol / l. Further, when a polyvalent electrolyte is used, its addition amount may be smaller. In the present invention, the objective can be sufficiently achieved by preliminarily charging the electrolyte into the system, or by post-adding it, but preferably by "electrolyzing after adding the electrolyte precursor" Further, good quality polyester resin particles can be obtained.

As the electrolyte precursor, for example, a salt which is hardly soluble at low temperature and easily soluble at high temperature, pH, temperature, pressure, light irradiation,
Examples of the compound include a compound that decomposes into an electrolyte by the like. In the present invention, ester compounds of amino alcohols and carboxylic acids can be used as preferred electrolyte precursors. Since such an ester compound has an amino group, it is water-soluble, and its aqueous solution is alkaline. When the temperature of the alkaline aqueous solution is raised, the ester bond is hydrolyzed to form a salt of amino alcohol and carboxylic acid. The amino group actually functions as a primary ammonium group or a tertiary ammonium group. Preferred amino alcohols in the present invention include amino ethanol, 1,3-amino propanol, 1,4-amino butanol, dimethyl amino ethanol, 1,3-dimethyl amino propanol and diethyl amino ethanol. , Diethylaminopropanol and the like can be used. Examples of the carboxylic acids include benzoic acid and its derivative, naphthalenecarboxylic acid, and its derivative, salicylic acid, thiosalicylic acid,
Phenylacetic acid, acetic acid, propionic acid, butyric acid, octanoic acid, decanoic acid, dodecanoic acid, lauric acid, stearyl acid, acrylic acid, methacrylic acid and the like can be used. Further, in the present invention, an ester in any combination of these amino alcohols and carboxylic acids can be preferably used as the electrolyte precursor. The particles thus obtained have a mean particle diameter D of 2 to 30 μm and a sharp particle diameter distribution in which 80 wt% or more of all the particles are present in the particle diameter range of 0.5D to 2.0D. . However, in the steps up to this point, the counter-cation of the ionic group contained in the obtained particles is a monovalent cation.

In the present invention, 30% or more of the total number of ionic groups are exchanged with divalent or more cations by further ion-exchanging the particles obtained thus far. As divalent or higher cations, Mg, Ca, Sr, Ba, Al,
Metal ions such as Zn, Cu, Ni, Co and Fe are preferable, moreover alkaline earth metal ions, further Ca,
Ba and Mg are preferable. The ion exchange treatment is performed by immersing the polyester particles in an aqueous solution of a salt containing these divalent or higher cations. At this time, it is preferable to heat the glass transition temperature of the polyester resin or higher. Further, when heated above the glass transition temperature, the dispersion stability of the polyester particles may be hindered by the addition of polyvalent ions, so inorganic particles such as silica, talc, titanium oxide, amphoteric latex, PVA, etc. You may use together the dispersion stabilizer of. Chlorides are preferred as salts of divalent or higher cations. The concentration of such salt is preferably selected so that the number of mols of the anions to be ion-exchanged contained in the treatment bath is about the same as or more than the total mols.

In the present invention, the slow aggregation is caused within the range of the glass transition temperature of the polyester resin ± 15 ° C, preferably within the range of the glass transition temperature + 5 ° C to the glass transition temperature -15 ° C, more preferably the glass transition temperature to the glass. Non-spherical particles can be obtained by realizing the transition temperature within the range of -10 ° C. When the polyester resin is slowly agglomerated at a temperature exceeding the glass transition temperature + 15 ° C, substantially spherical particles are produced, but such spherical particles are in the vicinity of the glass transition temperature, preferably in the range of about + 5 ° C to -20 ° C. Non-spherical particles can be obtained by performing compression treatment in the temperature range and then crushing.

Different kinds of aqueous dispersions can be incorporated into the polyester resin particles of the present invention by heteroaggregation during the particle growth process. It is also possible to use a polyester fine dispersion colored with a dye or the like. Furthermore, the dyeing can be performed before the ion exchange treatment or simultaneously with the ion exchange treatment. In this way it is possible to color and functionalize the particles. The heterogeneous water dispersion is, for example, a dispersion of pigment, latex, wax, carbon black, charge control agent and the like. As the dye, a disperse dye, an oil dye, a cationic dye, a basic dye, a reactive dye, a reactive disperse dye,
Vat dye or the like can be used. The obtained particles are washed and dehydrated, and then taken out as a dry powder by means such as freeze-drying, spray-drying, fluidized-drying, vacuum-drying, etc. Become a toner. Specific examples of the disperse dyes and oil dyes preferably used in the present invention include: C.I. I. Disperse Yellow 198 C.I. I. Disperse Yellow 42 C.I. I. Solvent Yellow 162 C.I. I. Disperse Red 92 C.I. I. Disperse Violet 26 C.I. I. Disperse Violet 35 C.I. I. Disperse Blue 60 C.I. I. Disperse Blue 87 C.I. I. Solvent Blue 64 C.I. I. Solvent Black 3 or the like can be used. Specific examples of basic dyes include C.I. I. Basic Yellow 11 C.I. I. Basic Yellow 13 C.I. I. Basic Yellow 21 C.I. I. Basic Red 14 C.I. I. Basic Red 15 C.I. I. Basic Red 39 C.I. I. Basic Violet 7 C.I. I. Basic Violet 11 C.I. I. Basic Violet 28 C.I. I. Basic Violet 40 C.I. I. Basic Violet C.I. I. Basic Blue 3 C.I. I. Basic Blue 75 or the like can be used.

The most significant feature of the present invention is that the anionic group contained in the polyester resin contains a cation having a valence of 2 or more as a counter cation. When the counter-cation of the anionic group is a monovalent cation, for example, sodium ion, ammonium ion, etc., it shows a very strong negative charge. However, when these monovalent cations are contained as counter-cations, their dissociation degree is relatively high, so that they are easily affected by environmental humidity. The amount becomes low, and the environmental stability as a toner is impaired. However, when a divalent or higher cation is used, the environmental stability of the charge amount is improved and the absolute value of the charge amount is reduced. Although the present inventors do not want to be bound by theory, it is considered that when a cation having a valence of 2 or more is used, the environmental stability is improved to some extent by first reducing the moisture absorption rate. Furthermore, since the absolute value of the amount of charge decreases, the degree of dissociation of ionic groups is involved in charging, and in a combination with a high degree of dissociation, cations are released and the amount of charge is low, indicating a high charge amount. It is considered that in the case of the cation, the absolute value of the charge amount decreases, and the combined action of these improves the stability of the charging environment. Further, the electrophotographic toner of the present invention has both stability in charging environment and good image characteristics, fixing characteristics, blocking resistance, storage stability and plasticizer resistance. This means that the present invention is based on none other than the polyester resin, and the polyester resin used in the present invention has a low melting temperature at a high temperature in the state where a relatively high glass transition temperature is maintained. Since the viscosity is realized and the affinity with the plasticizer contained in vinyl chloride resin, eraser, etc. is low, the plasticizer does not migrate to the toner resin, and the toner resin itself has a certain degree of crystallinity. This is because the inclusion of the color material in the toner is suppressed.
Therefore, even when the copy made by the toner using the polyester resin of the present invention is stored for a long period of time in a state of being in contact with a transparent vinyl chloride sheet, a plastic eraser, etc., the migration of the coloring material and the transfer of the resin to the sheet Does not cause adhesion.
Since the polyester resin of the present invention is excellent in color development in dyeing and has high stability to dyes, it exhibits high light fastness. Further, the toner according to the present invention is excellent in transparency and therefore not only the color development of the primary color but also the good color mixing property when superposed with other colors, and therefore the reproducibility of the intermediate color is excellent. Further, when an image is formed on a transparent film used in an over head projector or the like, a good color tone is exhibited even in an image projected on a screen.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto. [Polymerization of polyester resin] 112 parts by weight of dimethyl terephthalate, 76 parts by weight of dimethyl isophthalate, 6 parts by weight of 5 sodium sulfodimethyl isophthalate in an autoclave equipped with a thermometer and a stirrer. Parts, ethylene glycol 96 parts by weight, propylene glycol 50 parts by weight, and tetrabutoxy titanate 0.1 parts by weight were charged and the transesterification reaction was carried out by heating at 180 to 230 ° C. for 120 minutes. Next, the reaction system was heated to 250 ° C., and the reaction was continued for 60 minutes at a system pressure of 1 to 10 mmHg, and as a result, a copolyester resin (A1) was obtained. The composition, glass transition temperature, acid value, molecular weight and sodium sulfonate group equivalent of the obtained copolyester resin (A1) are shown in Table 1. Shown in. The composition of the polyester is NMR analysis, the glass transition temperature is DSC, the acid value is titrated, the molecular weight is GPC,
The sodium sulfonate group equivalent was determined by quantitative determination of S.
In the same manner as below, Table 1. Polyester resin (A
2) to (A4) were obtained.

[0026]

[Table 1]

In an autoclave equipped with a thermometer and a stirrer, 136 parts by weight of dimethyl terephthalate, 56 parts by weight of dimethyl isophthalate, 68 parts by weight of ethylene glycol, and bisphenol A 175 parts by weight of an ethylene oxide adduct (average molecular weight 350) and 0.1 part by weight of tetrabutoxy titanate were charged and heated at 150 to 220 ° C. for 180 minutes to carry out a transesterification reaction. Then, after raising the temperature to 240 ° C.,
Gradually reduce the system pressure to 10 mmHg after 30 minutes,
The reaction was continued for 60 minutes. After that, the atmosphere in the autoclave was replaced with nitrogen gas and the pressure was adjusted to atmospheric pressure. The temperature was kept at 200 ° C., 2 parts by weight of trimellitic anhydride was added, and the reaction was carried out for 60 minutes to obtain a copolyester resin (A5). The acid value of the obtained copolyester resin was 2.1 KOHmg.

Ethylene oxide adduct 70 of bisphenol A was placed in an autoclave equipped with a thermometer and a stirrer.
Parts by weight, maleic anhydride 19.6 parts by weight, hydroquinone 0.2 parts by weight, and nitrogen gas was introduced into the reaction system to maintain an inert atmosphere, and 0.05 parts by weight of dibutyltin oxide was added. A polyester resin (A6) was obtained by reacting at 200 ° C. Table 1. Medium, TBBA is tertiary butyl benzoic acid, NDC is 1,5 naphthalene dicarboxylic acid, TP
A is terephthalic acid, IPA is isophthalic acid, SIP is 5 sodium sulfoisophthalic acid, TMA is trimellitic acid, EG
Is ethylene glycol, PG is propylene glycol
, CHD is cyclohexanediol, TCDD is tricyclodecane dimethanol, BPE is an ethylene oxide adduct of bisphenol A (average molecular weight 350), and Tg is a glass transition temperature.

[Preparation of Polyester Water Fine Dispersion] Polyester resin (A1) 1 was placed in a four-necked 10-liter separable flask equipped with a thermometer, a condenser, and a stirring blade.
00 parts by weight and 75 parts by weight of butyl cellosolve are added to 70 ° C.
It was dissolved in. Then, 500 parts by weight of 70 ° C. ion water was added to disperse the water, and the mixture was distilled in a distillation flask until the distillate temperature reached 100 ° C. After cooling, water was added to make the solid content concentration 30%. The average particle size of the finely dispersed particles present in the obtained polyester water dispersion (B1) was 0.2 μm.
m and zeta potential were -52 mV. In the same manner, fine water dispersions (B2) to (B4) were obtained from the polyester resins (A2) to (A4). Polyester resin (A5)
Add 100 parts by weight, 50 parts by weight of butanol, 10 parts by weight of methyl ethyl ketone, and 20 parts by weight of isopropanol.
It melted at 0 ° C. Further, 1N aqueous ammonia solution was added to the acid value of the copolyester so that the acid value was 70%.
After maintaining the temperature at 30 ° C. and stirring for 30 minutes, 300 parts of water at 70 ° C. was added to obtain an aqueous microdispersion of copolyester. The obtained water dispersion was placed in a distillation flask, and the distillation temperature was set to 1
Distill until it reaches 00 ℃, then cool, adjust the solid content with deionized water, and finally remove the solvent to obtain a solid content of 30%.
A copolymerized polyester water microdispersion (B5) was obtained. Similarly, from polyester resin (A6) to water-based fine dispersion (B
6) was obtained.

[Preparation of Polyester Particles] Carbon Black PRINTEX150T [manufactured by Degussa] 200 parts by weight, partially esterified ammonia neutralized product of styrene / maleic acid copolymer resin (SMA1440 [manufactured by Atochem])
30 parts by weight and 770 parts by weight of deionized water were charged in a sand mill and dispersed for 180 minutes to obtain an aqueous dispersion of carbon black. 1000 parts by weight of the obtained polyester water-based fine dispersion (B1) was added to a 4-necked 5 liter separable flask equipped with a thermometer, a condenser and a stirring blade, and a car.
75 parts by weight of bonblack aqueous dispersion, and dimethylaminoethyl (2,2 dimethylol) as an electrolyte precursor
65 parts by weight of propionate was charged. Then, the temperature was raised to 75 ° C. and stirring was continued for 240 minutes. The finely dispersed particles present in the water-based finely dispersed body grew into united particles to obtain black polyester particles (C1K). The obtained particles were dehydrated and washed with a suction funnel and redispersed in deionized water to obtain an aqueous dispersion of polyester particles having a solid content concentration of 25% by weight. C2K in the same manner from polyester fine dispersions (B2) to (B6)
~ C6K was obtained.

[Ion exchange treatment] A beaker was charged with 300 parts by weight of an aqueous dispersion of black polyester particles (C1K) and 10 parts by weight of silica fine particles Aerosil # 200, and the mixture was stirred and mixed together by using an ultrasonic cleaner. The pH was then adjusted to 3 with hydrochloric acid. While continuing stirring, calcium chloride 1
0 part by weight was added, the temperature was raised to 80 ° C., the temperature was kept for 180 minutes, and then cooled to room temperature. Next, sodium hydroxide was added to adjust the pH to 13, and the mixture was dehydrated and washed with a suction funnel. The obtained cake was re-dispersed in water, adjusted to pH 13 with sodium hydroxide, dehydrated again, passed through diluted hydrochloric acid having a pH of 4 and then dehydrated and washed 3 times with ion-exchanged water to obtain a cake. After the cake was vacuum dried, it was crushed with a jet mill to obtain the results shown in Table 2. To obtain a black toner (D1K).
The average particle size and particle size distribution of the toner obtained by the corter counter method are shown in Table 2. The amount of the metal element (metal ion-based cation) contained in the obtained toner is determined by fluorescent X-ray analysis, and the nitrogen element (ammonium-based cation) is quantified by the Kjeldahl method. The results obtained by subtracting those contained in the dye are shown in Table 2. Shown in. Similarly, the polyester water microdispersion is replaced in the same manner as in Table 2. The toner shown in FIG. 5 parts by weight of the obtained toner and 95 parts by weight of a ferrite carrier F-100 [made by Powder Tech Co., Ltd.]
A two-component developer was obtained by stirring and mixing with a rumill. The resulting developer is vacuumed at 35 ° C in a standard environment of 25 ° C 60% RH.
After leaving each for 24 hours in a humid environment of 90% RH, the charge amount was measured by the blow-off method. The results are shown in Table 2. Shown in.

[0032]

[Table 2]

[0033]

[Comparative Example 1] Colored polyester particles C1K to C6K before ion exchange treatment were washed, dried and crushed to obtain a comparative toner.
Evaluation was performed in the same manner as in the example. The results are shown in Table 3. It can be seen that the charge amount is higher than that in the example, and that the charge amount decreases particularly during humidification.

[0034]

[Table 3]

[0035]

Example 2 (Preparation of Polyester Particles) The polyester aqueous dispersion (B) obtained in Example 1 was placed in a four-necked 5 liter separable flask equipped with a thermometer, a condenser and a stirring blade.
3) 1000 parts by weight, and 56 parts by weight of dimethylaminoethyl methacrylate as an electrolyte precursor were charged. Then, the temperature was raised to 75 ° C. and stirring was continued for 240 minutes. The finely dispersed particles present in the water-based finely dispersed body grew as a united particle, and colorless polyester particles (C3) having an average particle diameter of about 5.8 μm were obtained. The obtained particles are dehydrated and washed with a suction funnel and redispersed in deionized water to obtain a solid content of 25% by weight.
An aqueous dispersion of polyester particles was obtained.

(Dyeing) Disperse dye "CI Disper"
Se Yellow 198 "dry cake 10 parts by weight, sodium naphthalenesulfonate formalin condensate 10 parts by weight, deionized water 80 parts by weight, glass beads 2
00 parts by weight was placed in a Mayunez bottle and shaken and stirred for 30 minutes to obtain a disperse dye (DY). Similarly, "C.I. Dispe
rseRed 92 "," C.I. Disperse "
Using a blue 60 "dry cake, the disperse dye (D
M) (DC) was obtained. 300 parts by weight of the polyester particle aqueous dispersion (C3) and 30 parts by weight of disperse dye (DY) obtained above were placed in a stainless steel pot of a dyeing tester, Mini Color [made by Texum Giken], and a heating rate of 3 ° C./min. At 130 ° C
The temperature was raised to 60 ° C., held for 60 minutes, cooled to room temperature over 120 minutes, dehydrated and washed, and then redispersed in water to obtain a yellow-colored particle (C3Y) aqueous dispersion having a solid content concentration of 30 wt%. . Similarly, disperse dyes (DM) and (DC) were used to obtain an aqueous dispersion of magenta colored particles (C3M) and cyan colored particles (C3C).

[Ion exchange treatment] A beaker was charged with 300 parts by weight of a yellow-colored particle (C3Y) aqueous dispersion and 10 parts by weight of silica fine particles Aerosil # 200, and the mixture was stirred and mixed by using an ultrasonic cleaner. The pH was then adjusted to 3 with hydrochloric acid. While continuing stirring, 10 parts by weight of calcium chloride was added, the temperature was raised to 80 ° C., the temperature was maintained for 180 minutes, and then cooled to room temperature. Next, sodium hydroxide was added to adjust the pH to 13, and the mixture was dehydrated and washed with a suction funnel. The obtained cake was re-dispersed in water, adjusted to pH 13 with sodium hydroxide, dehydrated again, passed through diluted hydrochloric acid having a pH of 4 and then dehydrated and washed 3 times with ion-exchanged water to obtain a cake. After the cake was vacuum dried, it was crushed with a jet mill and the results are shown in Table 4. The yellow toner (D3Y) shown in FIG. The amount of metal element (metal ion cation) contained in the obtained toner was determined by fluorescent X-ray analysis, and the nitrogen element (ammonium cation) was determined by Kjeldahl method. Table 4. Shown in. The same applies to Table 4 below. The toner shown in FIG. The evaluation results are also shown in Table 4. Shown in. It shows stable charging characteristics against environmental temperature and humidity.

[0038]

[Table 4]

(Image Forming Test) Four color toners obtained by adding the black toner (D3K) obtained in Example 1 to the yellow, magenta and cyan color toners obtained in Example 2 are obtained. A color image forming test having continuous gradation was conducted by using an electrophotographic digital copying machine. The obtained image has excellent gradation reproducibility and intermediate color reproducibility, and has a resolution of 8
It was 00 DPI or more. Using these toners,
Similarly, a color image having continuous tone was formed on a transparent film for a bar head projector and projected on a white screen for observation. For comparison, a commercially available color
An image was similarly formed using a toner (a pigment was used as a coloring material), and the image was projected on a white screen and observed. When the toner of the present invention was used, a high-saturation projection image was obtained, but when the commercially available toner was used, the overall color tone was slightly dull, and especially the intermediate color portion had a slightly dark color tone.

[0040]

[Embodiment 3] The yellow color obtained in Embodiment 2 is applied to a beaker.
300 parts by weight of an aqueous dispersion of colored particles (C3Y), 10 parts by weight of silica fine particles Aerosil # 200, were charged and mixed with stirring by using an ultrasonic cleaner, and then the pH was adjusted to 3 with hydrochloric acid.
Was prepared. While continuing stirring, 5 parts by weight of barium chloride was added, the temperature was raised to 80 ° C., the temperature was maintained for 180 minutes, and then cooled to room temperature. Then add sodium hydroxide and p
H was adjusted to 13 and dehydrated and washed with a suction funnel. The cake thus obtained is re-dispersed in water and the pH is adjusted to 1 with sodium hydroxide.
Re-preparation to 3 and dehydration again, after passing diluted hydrochloric acid of pH 4 and repeating dehydration washing 3 times with ion-exchanged water, the cake obtained was vacuum dried and then crushed with a jet mill to obtain the results shown in Table 4. ． The toner (E1) shown in (1) was obtained. Similarly, barium chloride was added to 10 parts by weight and 20 parts by weight of toner (E2) (E3).
Got The same evaluations were made below, and the results are shown in Table 4.

[0041]

As described above, the electrophotographic toner of the present invention is extremely excellent as an electrophotographic toner having a very small change in charge amount due to the environment and having high definition and high color reproducibility. It has excellent characteristics. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yozo Yamada 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd.

Claims (1)

[Claims] 1. An average particle diameter D is 2 to 30 μm, and has a particle diameter distribution in which 80 wt% or more of all particles are present in a particle diameter range of 0.5 D to 2.0 D, and polycarboxylic acids and polycarboxylic acids are contained. A polyester resin obtained by condensation of valent alcohols and containing an anionic ionic group of 20 to 1000 eq./ton as a main component, and 30% of the total number of the ionic groups.
An electrophotographic toner characterized by containing the above-mentioned divalent or higher counter cations.