JP2963161B2 - Electrophotographic toner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toner for developing an electrostatic latent image formed in an electrophotographic method, an electrostatic printing method, an electrostatic recording method, or the like. More specifically, the present invention relates to a negatively charged toner used in electrophotography and the like. More specifically, the present invention relates to a negatively chargeable toner having excellent durability and capable of stably obtaining a good image.

(Prior art)

U.S. Pat.
Various methods are described in JP-A-23910 and JP-B-43-24748, but generally, a photoconductive substance is used, and an electric latent image is formed on a photoconductive support by various means. Then, the latent image is developed with toner to obtain a visible image, or, if necessary, a powder image is transferred to paper or the like and then fixed by heating, pressing, or solvent vapor to form a visible image. What you get.

Toners used in electrophotography are required to have various characteristics such as excellent chargeability, low environmental dependency, low deterioration with repeated use, and good fixability. I have. However, at present, it is not possible to sufficiently satisfy the chargeability, the durability in continuous use, and the compatibility between the fixability and the storage stability, and the demand for improvement of the toner cannot be tolerated.

Conventionally, a negatively chargeable polarity control agent for toner (hereinafter referred to as CCA)
As a metal complex with azo dyes such as Cr, Co, Fe, and Ni (U.S. Pat. No. 2,891,938, U.S. Pat. No. 2,891,939, U.S. Pat. No. 4,053,462, U.S. Pat.
937), metal complexes of salicylic acid with Cr, Co, Ni and the like (US Pat. No. 4,206,644), and salts of salicylic acid with Zn and Al. But,
All of these cannot be said to have a sufficient effect, and the effects vary depending on the compatibility of the toner with the binder-resin, and a sufficiently satisfactory one has not been obtained.

On the other hand, as binder resins for toners used in various developing methods, polyester resins are widely used because they have excellent low-temperature fixability and anti-offset properties, and have very little fusion to a vinyl chloride sheet. ing. JP
JP-A-63-2074 proposes a combination of a polyester resin synthesized from a bisphenol-type diol and a polycarboxylic acid with a metal salt of salicylic acid and / or a metal salt of a salicylic acid derivative. Although the effect of the present invention is effective, there is still a demand for improvement as compared with a toner using a styrene-acrylic resin as a binder resin for a toner. As described above, when the binder resin of the toner is a polyester resin, a combination with CCA that can obtain a sufficient polarity control effect is not known. Further, such a toner has a large change in chargeability due to the influence of the environment (temperature, humidity),
Since the charge amount increases under low humidity and decreases under high humidity, there is a problem in environmental stability. In response to this problem, the structure of polyester resin, such as its modification, was studied.
Many proposals have been made, but no satisfactory has been obtained.

〔Purpose〕

The present invention has been made in view of the conventional drawbacks, and its purpose is to specify a combination of a binder resin and CCA and a volume number resistance and a dielectric constant of a toner, thereby being excellent in chargeability and environmental stability. It is another object of the present invention to provide an electrophotographic toner which can provide stable performance even when used repeatedly over a long period of time. Still another object is to provide an electrophotographic toner capable of obtaining an image excellent in gradation.

Another object of the present invention is to provide an electrophotographic toner which exhibits good fixability from a low temperature, has a wide fixable temperature range, and does not have an image fused to a vinyl chloride sheet.

〔Constitution〕

As a result of intensive studies, the present inventors have found that the above and other objects can be achieved by the electrophotographic toner described below.

According to a first aspect of the present invention, in a toner for electrophotography, a binder resin of the toner is a polyester resin mainly synthesized from an alkylene glycol and a polycarboxylic acid, and a metal salicylate and / or a salicylic acid derivative is contained in the toner. Containing a metal salt, the volume resistivity of the toner is 2.0 × 1
0 ¹¹ [cm · Ω] or more, and the dielectric constant of the toner is 2.7
To 3.3, for an electrophotographic toner.

The present invention shown in FIG. 2 relates to an electrophotographic toner, wherein the binder resin of the toner is a polyester resin mainly synthesized from a bisphenol-type diol and a polycarboxylic acid, and the salicylic acid metal salt and / or It contains a metal salt of a salicylic acid derivative, and the volume resistivity of the toner is
The present invention relates to a toner for electrophotography, wherein the toner has a dielectric constant of not less than 2.0 × 10 ¹¹ [cm · Ω] and a dielectric constant of 2.7 to 3.3.

The acid value of the polyester resin in the present invention is 3 [KOH · m
g / g] or less, especially 2 [KOH · mg / g] or less, and the hydroxyl value is 40 [KOH · mg / g] or less, especially 30 [KOH · mg / g].
The following is preferred.

In a conventional toner, carbon black is mainly used as a colorant to exhibit black. Since carbon black is a conductive substance and a high dielectric substance, when dispersed and contained in toner, the conductivity of the toner itself increases, the volume specific resistance of the toner decreases, and the toner is charged. Τ = ε′ε ₀ ρ (where τ = relaxation time of charging ε ₀ = dielectric constant of vacuum ε ′ = specific dielectric constant of toner ρ = specific resistance of toner). For this reason, charge injection /
It is more susceptible to the effects of charge release and the like. As a result, when the dielectric constant is high and the volume resistivity is low, the charging time constant is small and the charging rise is good, but the charge is released quickly, and the problem of the re-induction phenomenon at the time of transfer is caused. And transfer becomes difficult.

On the other hand, the electrical characteristics of the binder resin itself of the toner also vary depending on the type of the resin. In general, the volume resistivity of resin used for toner is 10 ¹¹ to 10
It is between ¹² [cm · Ω], and the difference due to the resin is not so large. However, the dielectric characteristics vary depending on the structure of the resin itself. For example, in the case of a styrene-based resin, an acrylic-based resin, and a styrene-acryl-based copolymer, the dielectric constant of the resin itself is 1.8 to 2.2, which is about 2. In the case of a polyester resin, especially in the case of a polyester resin mainly synthesized from an alkylene glycol or a bisphenol-type diol and a polyvalent carboxylic acid, the dielectric constant of the resin itself is about 2.5 to 3.3. For this reason, even if carbon black is contained at a similar ratio, the electrical characteristics of the toner will change significantly due to the difference in the resin.
For this reason, when a polyester resin is used as a binder resin for a toner, if a coloring agent, a polarity control agent, and the like are contained in the same formulation as that of the styrene-acrylic copolymer, the electrical characteristics of the toner significantly change.

In the present invention, it has been obtained by focusing on the electrical properties of a polyester resin having many advantages such as excellent low-temperature fixability and offset resistance and the like.

In the present invention, it is important that the volume resistivity of the toner is 2.5 × 10 ¹¹ (cmΩ) or more, preferably 2.5 × 10 ¹¹ (cm
Ω] or more, particularly preferably 3.0 × 10 ¹¹ cm · Ω or more, and the dielectric constant of the toner is 2.7 to 3.3, preferably 2.
8 to 3.2, particularly preferably 2.9 to 3.1.
When the volume resistivity of the toner is less than 2.0 × 10 ¹¹ [cm · Ω], the dielectric relaxation time τ = ε′ε ₀ ρ of the toner becomes too short, so that a defective image is likely to occur in the transfer process.
In addition, since it is more susceptible to the influence of electrostatic induction, it causes a development defect and a fixing offset phenomenon. Further, the charge amount of the toner is also reduced, which causes toner scattering and background contamination. When the dielectric constant of the toner is 3.3 or more,
The level of the saturation charge amount of the toner is increased, and the development is likely to be defective to insufficient image density.

The electrical properties of the toner of the present invention can be measured, for example, as follows. 3.0 g of toner about 500 kgf / cm ²
A tablet having an area of 12.5 cm ² and a thickness of about 1.8 to 2.2 mm was pressurized and applied with a frequency of 1 kHz using a commercially available dielectric loss measuring device (TR-10C: manufactured by Ando Electric Co., Ltd.). The measurement is performed in the state, and the volume resistivity and the dielectric constant are calculated from this.

The metal salt of a salicylic acid and / or a metal salt of a salicylic acid derivative of the present invention is represented by the following general formula.

(However, R ¹ , R ² , and R ³ are preferably hydrogen or an alkyl group having 1 to 10 carbon atoms or an allyl group. Here, R ¹ , R ² ,
And R ³ may be the same or different. Also, Me
Is any metal selected from zinc, nickel, cobalt, lead, and chromium, of which zinc is particularly desirable. The metal salt represented by the general formula is CLARK, JLKao,
H. (1948) J. Amer. Chem. Soc. 70, 2151. For example, 2 mol of salicylic acid sodium salt (including the sodium salt of a salicylic acid derivative) and 1 mol of zinc chloride are added to a solvent, mixed, heated and stirred to obtain a zinc salt. . Metal salts other than zinc salts can also be produced according to the above method.

The salicylic acid metal salt and the metal salt of the salicylic acid derivative are white crystals and have a relatively small molecular weight, so that they are well dispersed in the binder resin and do not substantially show coloring in the toner. is there. The addition amount of these salicylic acid metal salts and salicylic acid derivative metal salts can be determined in consideration of other conditions such as the production method including the chargeability and dispersion method of the binder resin and the chargeability of other additives. Is about 0.1 to 5 wt% with respect to the toner binder resin,
Preferably, it is in the range of 0.5 to 3 wt%. If it is less than 0.1 wt%, the effect of controlling the charge is small, and if it is more than 5 wt%, the transparency of the toner may be impaired, and a clear color may not be developed.

Conventionally, the polarity control effect of salicylic acid metal salts and salicylic acid derivative metal salts has been known, but a sufficient effect has not been obtained in combination with a polyester resin. It is considered that this is mainly due to the electrical properties of the toner and the dispersion state of the metal salt of salicylic acid and / or the metal salt of salicylic acid derivative in the resin.

Polyester resins are generally quite dense in structure, exhibit slow diffusion of dye molecules into the interior of the resin, and exhibit difficulty in dyeing. Further, since the polyester resin has a large negative interface potential, dyeing / dispersion of the anionic dye is prevented. Generally, salicylic acid metal salts and metal salts of salicylic acid derivatives are anionic, and it is difficult to satisfactorily disperse them in a resin having a negative interface potential. For this reason, it is considered that good results have not been obtained conventionally when a salicylic acid metal salt and a metal salt of a salicylic acid derivative are contained as a polyester resin and a polarity controlling agent. What greatly affects the negative interface potential of the polyester resin is the acid value and hydroxyl value of the resin, particularly the acid value. Therefore, the dispersibility of the dye in the resin can be improved by suppressing the acid value and the hydroxyl value as much as possible.

In the present invention, the acid value of the polyester resin is 3 [KOHmg /
g] or less and a hydroxyl value of 40 [KOHmg / g] or less can provide good toner characteristics. More preferably, the polyester resin has an acid value of 2 [KOHmg / g] or less and a hydroxyl value of 30 [K
OHmg / g] or less, good toner characteristics can be obtained. When the acid value of the polyester resin is 3 [KOH mg / g] or more, the negative chargeability of the resin itself becomes strong, the charge amount increases under low humidity, and the dispersibility of the dye also deteriorates. Hydroxyl value is 40 [KOHmg /
g] or more, the charge amount is greatly reduced under high humidity. In addition, an increase in the number of low molecular weight polymers inevitably causes problems such as offset resistance and blocking resistance.

The acid value / hydroxyl value of the polyester resin in the present invention is measured according to the method of JIS K0070.

The binder resin of the toner used in the present invention is a polyester resin mainly synthesized from an alkylene glycol and / or a bisphenol-type diol polycarboxylic acid. A polyester resin synthesized from an alkylene glycol and / or a polyvalent carboxylic acid has excellent fixability from a low temperature and has a wide fixing temperature range. Further, it is excellent in manufacturability, especially in pulverizability, and is advantageous in toner production cost.

As the alkylene glycol used in the present invention,
For example, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and the like can be mentioned.
Among them, ethylene glycol, 1,3-propylene glycol and 1,4-betanediol are preferably used.

Examples of the bisphenol type diol used in the present invention include (a) polyoxypropylene (2,2) -2,2
-Bis (4-hydroxyphenyl) propane, (b) polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane, (c) polyoxystyrene (6)
-2,2-bis (4-hydroxyphenyl) propane,
(D) polyoxybutylene (2) -2,2-bis (4-hydroxyphenyl) propane, (e) polyoxypropylene (3) -bis (4-hydroxyphenyl) thioether, (f) polyoxypropylene (2 ) -2,2-bis (4-cyclohexanol) propane, (g) polyoxyethylene (2) -2,6-dichloro-4-hydroxyphenyl, (h) polyoxyethylene (2,5) -p, p-bisphenol, (i) polyoxybutylene (4) -bis (4-hydroxyphenyl) ketone, (j) oxyethylene-2,2-bis (4-hydroxyphenyl) propane, (k) oxypropylene-2, 2-bis (4-hydroxyphenyl) propane and the like.

In addition, when using an alkylene glycol, a bisphenol-type diol can be used in combination as necessary,
When a bisphenol-type diol is used, an alkylene glycol can be used together if necessary. Further, in any case, as the other alcohol component, for example, aliphatic polyols such as diethylene glycol, triethylene glycol, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can be used as necessary.

Examples of the polyvalent carboxylic acid used in the present invention include, as divalent aromatic carboxylic acids, derivatives such as phthalic acid, isophthalic acid, phthalic anhydride, terephthalic acid, and esters. As the carboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
There are 2,5,7-naphthalenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid and their anhydrides and esterified products. Examples of the divalent aliphatic carboxylic acid include, for example, maleic acid, fumaric acid, succinic acid, adipic acid, sebacic acid, malonic acid, and substitution of these with a saturated or unsaturated hydrocarbon group having 8 to 22 carbon atoms. Divalent organic acid monomers, anhydrides thereof, dimers of lower alkyl esters and linoleic acid, and other divalent organic acid monomers.

The toner of the present invention may contain a known toner resin for the purpose of improving the properties of the toner such as fluidity, non-filming property, pulverizability, charging property and fixing property. For example, polystyrene, poly p-styrene, a homopolymer of styrene and its substituted body such as polyvinyl toluene,
Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-
Ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α- Chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene- Maleic acid copolymer, styrene-based copolymers such as styrene-maleic acid ester copolymer, polymethyl methacrylate, polybutyl methacrylate,
Polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or aliphatic hydrocarbon resin, aromatic Petroleum resins, chlorinated paraffins, paraffin waxes and the like can be used alone or as a mixture.

These resins, as long as the effects of the present invention are not impaired,
It can be contained at a content of 40% by weight or less of the binder.

As the colorant used in the present invention, any known colorants for toner can be used. As the black colorant, for example, carbon black, aniline black, furnace black, lamp black and the like can be used. Other coloring agents include, for example, phthalocyanine blue, methylene blue, Victoria blue, methyl violet, aniline blue, ultramarine blue, rhodamine 6G lake, watching red, rose bengal, rhodamine B, alizarin lake, chrome yellow, benzidine yellow, Hansa Yellow, naphthol yellow, molybdenum orange, quinoline yellow, tartrazine and the like can be used. Further, these two or more kinds of colorants can be used in combination. here,
Since the type and amount of the colorant greatly affect the volume resistivity and the dielectric constant of the toner, the conductivity and dielectric constant of the colorant should be carefully examined to determine the type and the amount of the colorant.

The toner of the present invention may be used, if necessary, with additives for toner generally widely used, for example, fluidizing agents such as colloidal silica, metal oxides such as titanium oxide and aluminum oxide, and polishing of silicon carbide and the like. And a lubricant such as a fatty acid metal salt.

The toner of the present invention can be used either as a one-component developer or as a two-component developer by mixing with a carrier. When used as a two-component developer, conventionally known carriers can be used. For example, iron powder having a particle size of about 20 to 200 μm, nickel powder, ferrite powder, magnetite powder, glass beads,
Alternatively, a material obtained by using these as a core material and coating the surface thereof with a resin such as a fluorine-based resin, a silicone resin, a styrene-based resin, or an acrylic-based resin can be used.

Hereinafter, the present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto. In the description, “parts” means parts by weight.

〔Example〕

Example 1 [Production of polyester resin] 7 mol of terephthalic acid, 2 mol of trimellitic acid and 7 mol of ethylene glycol, polyoxypropylene (2,2)
2 mol of 2,2-bis (4-hydroxyphenyl) propane was condensed by a conventional method to synthesize a polyester resin. Careful attention was paid so that each monomer did not distill or escape during the synthesis, and when distilling or escaped, only that amount was added on the way. Oxidation of the obtained polyester resin was 1.3 [KOHmg / g] · hydroxyl value 28 [KOHmg / g].

[Production of toner]

100 parts of the above polyester 100 parts carbon black 2 parts charge control agent 1 part (3,5-di-t-butylsalicylate zinc compound) The mixture of the above composition is melt-kneaded, cooled, pulverized, classified,
A black toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner was 5.8 × 10 ¹¹ [cm · Ω], and the dielectric constant was 3.2.

[Live-action test]

To 3 parts of the toner prepared as described above, 97 parts of a styrene-based resin-coated carrier were mixed by a ball mill,
A developer was prepared.

Next, the above developer was set in an IMAGIO320 digital copying machine manufactured by Ricoh Co., Ltd., and an image test was performed. As a result, a good image having good solid gradation and no fog was obtained. When a copied image was repeatedly formed, the image did not change even after 50,000 sheets of image were output.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was −20.8 μC / g, and the charge amount of the toner after running 100,000 sheets was −18.6 μC / g, which is almost the same as the initial value. Did not. Also, images equivalent to normal humidity were obtained in a high humidity environment of 35 ° C. and 90% RH and in a low humidity environment of 10 ° C. and 15% RH.

Example 2 [Production of polyester resin] 7 mol of terephthalic acid, 2 mol of trimellitic acid, 1,3-
A polyester resin was synthesized in the same manner as in Example 1, except that 7 mol of propylene glycol, 1.84 mol of polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane and 0.16 mol of glycerin were used. The acid value of the obtained polyester resin was 1.3 [KOHmg / g]. The hydroxyl value was 28 [KOHmg / g].

[Production of toner]

80 parts of the above-mentioned polyester 20 parts of styrene-n-butyl methacrylate 20 parts Copolymer (Mw = 400000) CI Pigment Red 122 3 parts Charge control agent 1 part (Chromium 3,5-di-t-butylsalicylate compound) Mixture of the above composition Melt kneading, cooling, pulverizing, classifying,
A red toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner was 4.6 × 10 ¹¹ [cm · Ω], and the dielectric constant was 3.0.

[Live-action test]

3 parts of the toner prepared as described above and 97 parts of the silicone resin-coated carrier were mixed by a ball mill to prepare a developer.

Next, an image test was performed on the developer in the same manner as in Example 1. As a result, a good image having good solid gradation and no fog was obtained. When a copied image was repeatedly formed, the image did not change even after 50,000 sheets of image were output.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was −18.3 μC / g, and the charge amount of the toner after running 100,000 sheets was −16.2 μC / g, which is almost the same as the initial value. Did not. Also, images equivalent to normal humidity were obtained in a high humidity environment of 35 ° C. and 90% RH and in a low humidity environment of 10 ° C. and 15% RH.

Example 3 [Production of polyester resin] 7 mol of terephthalic acid, 2 mol of trimellitic acid, 1,4-
6 mol of butanediol, oxypropylene (2) -2,2
A polyester resin resin was synthesized in the same manner as in Example 1 except that 2.84 mol of -bis (4-hydroxyphenyl) propane and 0.16 mol of glycerin were used. The acid change of the obtained polyester resin is 0.9 (KOHmg / g) and the hydroxyl value is 36.
[KOHmg / g].

[Production of toner]

80 parts of polyester described above 20 parts of styrene-n-butyl methacrylate Copolymer (Mw = 400000) CI Pigment Blue 15 1.5 parts Charge control agent 1 part (Chromium 3,5-di-t-butylsalicylate compound) Mixture of the above composition Melt kneading, cooling, pulverizing, classifying,
A blue toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner is 3.2 × 10 ¹¹ [cmΩ].
The dielectric constant was 3.2.

[Live-action test]

3 parts of the toner prepared as described above and 97 parts of the silicone resin-coated carrier were mixed by a ball mill to prepare a developer.

Next, an image test was performed on the developer in the same manner as in Example 1. As a result, a good image having good solid gradation and no fog was obtained. When a copied image was repeatedly formed, the image did not change even after 50,000 sheets of image were output.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was −19.8 μC / g, and the charge amount of the toner after running 100,000 sheets was −18.1 μC / g, which is almost the same as the initial value. Did not. Also, images equivalent to normal humidity were obtained in a high humidity environment of 35 ° C. and 90% RH and in a low humidity environment of 10 ° C. and 15% RH.

Comparative Example 1 [Production of Toner] 100 parts of polyester of Example 1 10 parts of carbon black 1 part of charge control agent (3,5-di-t-butylsalicylate zinc compound) A mixture having the above composition was melt-kneaded, cooled, pulverized, Classify,
A black toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner was 5.2 × 10 ¹¹ [cm · Ω], and the dielectric constant was 3.5.

[Live-action test]

A developer was prepared from the toner prepared as described above in the same manner as in Example 1, and an image test was performed. As a result, the obtained image had a lot of fog, and was an image in which solids were prominent. Further, when a copy image was repeatedly formed, the image was output on about 10,000 sheets, and toner scattering in the copying machine became severe.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was -17.3 μC / g, and the charge amount of the toner after running 10,000 sheets was -6.6 μC / g.

Comparative Example 2 [Production of Toner] 100 parts of polyester of Example 2 Styrene-n-butyl methacrylate 20 parts Copolymer (Mw = 400,000) CI Pigment Red 122 6 parts Melt-kneading, cooling, pulverizing and classifying a mixture having the above composition. And
A red toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner was 8.9 × 10 ¹¹ [cm · Ω], and the dielectric constant was 3.4.

[Live-action test]

97 parts of the carrier of Example 1 and 3 parts of the toner prepared as described above were mixed by a ball mill to prepare a developer.

Next, the above developer was set on an IMAGIO320 digital copier manufactured by Ricoh Co., Ltd., and an image test was performed. As a result, the image was fogged, and the solid image was prominent. Further, when a copy image was repeatedly formed, the image was output on about 10,000 sheets, and toner scattering in the copying machine became severe.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was −20.1 μC / g, and the charge amount of the toner after running 10,000 sheets was −7.2 μC / g.

Example 4 [Production of polyester resin] Example 1 was repeated except that 7 mol of terephthalic acid, 2 mol of trimellitic acid and 9 mol of polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane were used. A polyester resin was synthesized in the same manner as described above. Careful attention was paid so that each monomer did not distill or escape during the synthesis, and when distilling or escaped, only that amount was added on the way. The acid value of the obtained polyester resin is 1.5 (KOHmg /
g]. The hydroxyl value was 35 [KOHmg / g].

[Production of toner]

100 parts of the above polyester 100 parts carbon black 2 parts charge control agent 1 part (3,5-di-t-butylsalicylate zinc compound) The mixture of the above composition is melt-kneaded, cooled, pulverized, classified,
A black toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner was 5.8 × 10 ¹¹ [cm · Ω], and the dielectric constant was 3.2.

[Live-action test]

To 3 parts of the toner prepared as described above, 97 parts of a styrene-based resin-coated carrier were mixed by a ball mill,
A developer was prepared.

Next, the above developer was set in an IMAGIO320 digital copying machine manufactured by Ricoh Co., Ltd., and an image test was performed. As a result, a good image having good solid gradation and no fog was obtained. When a copied image was repeatedly formed, the image did not change even after 50,000 sheets of image were output.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was -19.6 μC / g, and the charge amount of the toner after running 100,000 sheets was −17.8 μC / g, which is almost the same as the initial value. Did not. Also, images equivalent to normal humidity were obtained in a high humidity environment of 35 ° C. and 90% RH and in a low humidity environment of 10 ° C. and 15% RH.

Example 5 [Production of polyester resin] Except that 7 mol of terephthalic acid, 2 mol of trimellitic acid, 8.84 mol of polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane and 0.16 mol of glycerin were used. A polyester resin was synthesized in the same manner as in Example 1. The acid value of the obtained polyester resin is 1.2 (K
OH mg / g]. The hydroxyl value was 29 [KOH mg / g].

[Production of toner]

80 parts of the polyester described above 20 parts of styrene-n-butyl methacrylate copolymer (Mw = 400000) 3 parts of CI Pigment Red 122 1 part of a charge control agent 1 part (zinc 3,5-di-t-butylsalicylate compound) A mixture of the above composition Melt kneading, cooling, pulverizing, classifying,
A red toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner was 4.6 × 10 ¹¹ [cm · Ω], and the dielectric constant was 3.0.

[Live-action test]

3 parts of the toner prepared as described above and 97 parts of the silicone resin-coated carrier were mixed by a ball mill to prepare a developer.

Next, an image test was performed on the developer in the same manner as in Example 1. As a result, a good image having good solid gradation and no fog was obtained. When a copied image was repeatedly formed, the image did not change even after 50,000 sheets of image were output.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was −21.8 μC / g, and the charge amount of the toner after running 100,000 sheets was −19.6 μC / g, which is almost the same as the initial value. Did not. Also, images equivalent to normal humidity were obtained in a high humidity environment of 35 ° C. and 90% RH and in a low humidity environment of 10 ° C. and 15% RH.

Example 6 [Production of polyester resin] 7 mol of terephthalic acid, 2 mol of trimellitic acid, 4.84 mol of polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2)
A polyester resin was synthesized in the same manner as in Example 1, except that 4 mol of -2,2-bis (4-hydroxyphenyl) propane and 0.16 mol of glycerin were used. The acid value of the obtained polyester resin is 0.9 (KOHmg / g) -hydroxyl value 38
[KOHmg / g].

[Production of Toner] 80 parts of the above-mentioned polyester 20 parts of styrene-n-butyl methacrylate Copolymer (Mw = 400000) CI Pigment Blue 15 1.5 parts Charge control agent 1 part (3,5-di-t-butylsalicylate chromium compound) The mixture having the above composition was melt-kneaded, cooled, pulverized, and classified to obtain a blue toner having a particle size of 5 to 20 μm. The volume resistivity of the obtained toner was 3.2 × 10 ¹¹ [cm · Ω], and the dielectric constant was 3.2.

[Live-action test]

3 parts of the toner prepared as described above and 97 parts of the silicone resin-coated carrier were mixed by a ball mill to prepare a developer.

Next, an image test was performed on the developer in the same manner as in Example 1. As a result, a good image having good solid gradation and no fog was obtained. When a copied image was repeatedly formed, the image did not change even after 50,000 sheets of image were output.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was -19.3 μC / g, and the charge amount of the toner after running 100,000 sheets was −17.6 μC / g, which is almost the same as the initial value. Did not. Also, images equivalent to normal humidity were obtained in a high humidity environment of 35 ° C. and 90% RH and in a low humidity environment of 10 ° C. and 15% RH.

Comparative Example 3 [Production of Toner] 100 parts of polyester of Example 3 10 parts of carbon black 1 part of charge control agent (3,5-di-t-butylsalicylate zinc compound) A mixture having the above composition was melt-kneaded, cooled, pulverized, Classify,
A black toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner was 5.2 × 10 ¹¹ [cm · Ω], and the dielectric constant was 3.5.

[Live-action test]

A developer was prepared from the toner prepared as described above in the same manner as in Example 1, and an image test was performed. As a result, the obtained image had many fogs and was a solid and prominent image. Further, when a copy image was repeatedly formed, the image was output on about 10,000 sheets, and toner scattering in the copying machine became severe.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was −15.8 μC / g, and the charge amount of the toner after running 10,000 sheets was −5.7 μC / g.

Comparative Example 4 [Production of Toner] 100 parts of polyester of Example 2 Styrene-n-butyl methacrylate 20 parts Copolymer (Mw = 400000) CI Pigment Red 122 6 parts The mixture having the above composition was melt-kneaded, cooled, pulverized, and classified. And
A red toner having a particle size of 5 to 20 μm was obtained. The volume resistivity of the obtained toner was 8.9 × 10 ¹⁰ [cm · Ω], and the dielectric constant was 3.4.

[Live-action test]

97 parts of the carrier of Example 1 and 3 parts of the toner prepared as described above were mixed by a ball mill to prepare a developer.

Next, the above developer was set in a Ricoh IMAGIO320 digital copier, and an image test was conducted. As a result, the image was fogged and the solid image was sharp. Further, when a copy image was repeatedly formed, the image was output on about 10,000 sheets, and toner scattering in the copying machine became severe.

When the charge amount of the toner was measured by a blow-off method, the initial charge amount was −22.7 μC / g, and the charge amount of the toner after running 10,000 sheets was −6.4 μC / g.

〔effect〕

According to the present invention, a high-quality image excellent in solid gradation can be obtained. Even after continuous copying, an image having the same quality as the initial image can be obtained, and a fresh image can be obtained without a change in the amount of negative charge and little environmental change. In addition, a good image can be obtained from a low temperature, exhibiting good fixability and having no fusion to a vinyl chloride sheet.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihisa Okamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Kayo Makita 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (56) References JP-A-2-129653 (JP, A) JP-A-3-163564 (JP, A) JP-A-55-129358 (JP, A) JP-A-64-84281 ( JP, A) JP-A-1-96681 (JP, A) JP-A-63-148271 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/00-9/10 362

Claims (3)

(57) [Claims] In an electrophotographic toner, a binder resin of the toner is a polyester resin mainly synthesized from an alkylene glycol and a polycarboxylic acid, and a metal salt of a salicylic acid salt and / or a metal of a salicylic acid derivative is contained in the toner. Containing a salt, the volume resistivity of the toner is 2.0 × 10 ¹¹ (c
mΩ) or more, and the toner has a dielectric constant of 2.7 to 3.3.
An electrophotographic toner, comprising: 2. In an electrophotographic toner, the binder resin of the toner is a polyester resin mainly synthesized from a bisphenol-type diol and a polyvalent carboxylic acid, and a metal salt of salicylic acid and / or a salicylic acid derivative is contained in the toner. Containing metal salt, the volume resistivity of the toner is 2.0 × 10
¹¹ [cm · Ω] or more, and the dielectric constant of the toner is 2.7
-3.3, a toner for electrophotography. 3. The polyester resin having an acid value of 3 [KOH · m
g / g] or less, and the hydroxyl value is 40 [KOH.mg/g] or less.