JP2737015B2 - Electrostatic image developing toner and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic image used in an electrophotographic method, an electrostatic printing method, and a magnetic recording method, and particularly to a toner suitable for a hot roll fixing method. And its manufacturing method.

[Prior Art] Conventionally, many electrophotographic methods have been known as described in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. However, generally, a photoconductive substance is used to form an electric latent image on the photoreceptor by various means, and then the latent image is developed using toner, and if necessary, transferred to paper or the like. After a toner image is transferred to a material, the image is fixed by heating, pressure, solvent vapor, or the like to obtain a copy.

In the step of developing the above-described electric latent image using the toner, it is necessary to impart a charge to the toner. This method uses a known method such as a triboelectric charging method, an ion irradiation method, and conductivity. Although there are an electrostatic induction method and a charge injection method, a friction charging method and a contact charging method are most easily used and widely used.

In this case, in order to apply a charge to the toner, frictional charging of the toner with a charging blade, a developing sleeve, or the like is used,
A one-component developing method using frictional charging between toners and a two-component developer in which carrier particles charged to the opposite polarity to the toner are mixed with the toner are known.

When such a toner is charged by friction or contact, it is necessary to include a substance which controls charge in the toner. As such a charge control agent, a powder obtained by dispersing a colorant, magnetic particles, and the like in a binder resin is widely used.

Examples of the binder resin include a synthetic resin or a natural resin such as a vinyl resin, a polyester resin, an epoxy resin, a phenol resin, a polyurethane resin, a polyether resin, and a cellulose resin. Based resins are most widely used. This is because there are many types of monomer compositions and the molecular weight can be easily adjusted.

Such a vinyl resin or divinyl resin can be synthesized by a known polymerization method, that is, a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, or a suspension polymerization method.

In the bulk polymerization method, a polymer having a low molecular weight can be obtained by polymerizing at a high temperature to reduce the termination reaction rate, but there is a problem that the reaction is difficult to control.
In this regard, in the welding polymerization method, a low molecular weight polymer can be easily obtained under mild conditions by utilizing the difference in radical chain transfer depending on the solvent and by adjusting the amount of the initiator and the reaction temperature. It is preferable to obtain a low molecular weight compound in the resin composition used in the above. However, when the offset resistance is taken into consideration, it is preferable to increase the amount of the gel component in the crosslinked region until the component becomes insoluble in the solvent. In this respect, the solution polymerization method has a problem.

On the other hand, the emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed as small particles in an aqueous phase using an emulsifier, and polymerization is carried out using a water-soluble polymerization initiator. In this method, it is easy to control the heat of reaction, and since the phase in which the polymerization is carried out (the oil phase composed of the polymer and the monomer) and the aqueous phase are different, the termination reaction rate is small, and as a result, the polymerization rate is large. , With a high degree of polymerization. Further, the reason is that the polymerization process is relatively simple, and that the polymerization product is fine particles, so that it is easy to mix with a colorant, a charge control agent, and other additives in the production of a toner. This is advantageous as compared with other methods as a method for producing a binder resin for a toner.

However, in the emulsion polymerization method, a monomer insoluble in water is emulsified and dispersed in water with an emulsifier to carry out polymerization, so that it is unavoidable that the polymerization product contains impurities due to the emulsifier. This has an adverse effect on physical properties, especially triboelectricity, durability and the like. As a countermeasure, for example, in Japanese Patent Publication No. 63-60906, after the emulsion polymerization is completed, a coagulant is added to an emulsion containing a particulate resin to coagulate the resin, and the coagulated resin is treated with an alkaline aqueous solution, or A method in which the suspension is added to a coagulation solvent such as alcohol to coagulate the resin is used, but it is extremely difficult to completely remove the impurities by any method.

From the above, a suspension polymerization method is mentioned as a preferable resin production method. In this method, a monomer containing a low molecular weight polymer in a suspended state is polymerized together with a crosslinking agent. The resin composition obtained by this method has a pearl-like shape, and is in a preferable state in which low to high molecular weight polymers, including crosslinked regions, are uniformly mixed. However, when using this method, the monomers need to be well dispersed in the suspension. For this reason, it is preferable to add a small amount of a dispersant. However, the dispersant orients in the vicinity of the surface of the produced polymer particles, and may particularly adversely affect the chargeability.

[Problem to be Solved by the Invention] An object of the present invention is to provide a toner which has solved the above-mentioned problems.

That is, an object of the present invention is to provide a toner which uses a resin obtained by a suspension polymerization method as a binder resin and which solves the above-mentioned problems.

It is a further object of the present invention to provide a toner which is excellent in chargeability and has a fast rise.

Another object of the present invention is to provide a toner capable of controlling the charge amount and having a sharp charge distribution.

Furthermore, the object of the present invention is the stability over time in the charging ability,
An object of the present invention is to provide a toner having excellent environmental stability.

A further object of the present invention is to provide a toner having excellent offset resistance and high production efficiency.

It is a further object of the present invention to provide a toner which is excellent in low-temperature fixability and has improved blocking resistance.

[Means and Actions for Solving the Problems] The present invention relates to a toner for developing an electrostatic image, which is manufactured through a step of melt-kneading at least a binder resin and a colorant, and contains at least the binder resin and the colorant. The binder resin is composed of a half-ester monomer of dicarboxylic acid in an amount of 1 to 30% by weight based on all monomers and another copolymerizable monomer as constituents, and is synthesized by suspension polymerization using a dispersant. A copolymer, wherein the copolymer has been subjected to alkali treatment by treating the suspension after completion of suspension polymerization with an alkaline aqueous solution, and relates to a toner for developing an electrostatic image. .

Further, the present invention provides a method for producing an electrostatic image developing toner having a step of melt-kneading at least a binder resin and a coloring agent, and a pulverizing step of pulverizing the obtained kneaded material, wherein 1 to 30 A copolymer is synthesized by suspension polymerization using a dispersing agent, using a half-percent dicarboxylic acid half-ester monomer and another monomer capable of copolymerization. The present invention relates to a method for producing a toner for developing an electrostatic image, wherein an alkali-treated copolymer obtained by treating with an alkaline aqueous solution is used as the binder resin.

 The present invention will be described in detail below.

As a result of intensive studies, we have found that it is extremely effective to include an acid component in the binder resin in order to achieve the above-mentioned object. The reason for this is that by introducing an acid component, the polarity of the resin itself can be increased, the affinity for paper is improved and the fixability is improved, and the affinity of the toner for the fixing roller is weakened.
The crosslinking reaction with a metal compound added separately at the time of melt-kneading eliminates roller contamination and wrapping, thereby increasing the strength of the toner and giving good results with respect to blocking resistance and offset resistance.

As the carboxylic acid monomer that can be used in the suspension polymerization that can be used in the present invention, a half-ester monomer of dicarboxylic acid with low water solubility is preferable, for example, monomethyl maleate, monoethyl maleate, monobutyl maleate Half-esters of α, β-unsaturated dicarboxylic acids such as monooctyl maleate, monoallyl maleate, monophenyl maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monophenyl fumarate, etc .; Half-esters of alkenyl dicarboxylic acids such as monobutyl butenylsuccinate, monomethyl n-octenylsuccinate, monoethyl n-butenylmalonate, monomethyl n-dodecenylglutarate, monobutyl n-butenyladipate; monomethyl phthalate; Half esters of aromatic dicarboxylic acids such as monoethyl phthalate and monobutyl phthalate; and the like.

The above-mentioned dicarboxylic acid half ester may be added in an amount of 1 to 30% by weight, preferably 3 to 20% by weight, based on all monomers constituting the binder resin.

Further examination of binder resin,
It has been found that the ratio can be achieved when the ratio of the THF-insoluble component of the binder resin and the molecular weight distribution of the THF-soluble component are specified. When the binder resin is dissolved in a solvent such as THF, the insoluble matter and the soluble matter can be separated, and the molecular weight distribution of the soluble matter can be measured by GPC. Focusing on the position of the peak of the molecular weight distribution of the THF-soluble component in the THF-soluble component, a system having no or a small amount of the THF-insoluble component is very disadvantageous in pulverizability. The direction in which the peak position of the molecular weight distribution of the soluble component is simply shifted to the position of a low molecular weight deteriorates the offset resistance, which confirms that it is difficult to satisfy both the offset resistance and the crushability. .

From this study, it has been found that it is very effective to include a specific amount of THF-insoluble matter not only for offset resistance but also for improving pulverizability as generally considered.

In view of the above and in addition to the foregoing, we considered suspension polymerization to be the most preferred polymerization method for resin production.

However, in the suspension polymerization, it is necessary to uniformly disperse the constituent monomers in an aqueous solvent, and when the dispersion is not uniform, the polymerization does not proceed well. For this reason, a method of adding a dispersant to the aqueous solvent has been preferably used, but the dispersant has an arrangement in which a hydroxyl group is oriented toward a polymer particle, particularly a carboxylic acid group or its ester residue present near the surface. Take. For this reason, the produced toner has an adverse effect on chargeability, particularly on environmental stability (particularly in a low-temperature and low-humidity environment). The present invention proposes to treat the suspension with an aqueous alkaline solution in order to eliminate this adverse effect.

That is, it proposes that after the suspension polymerization is completed, the dispersant is removed by adding an alkaline aqueous solution to the suspension dispersion. In this case, the aqueous alkali solution is added so that the pH of the suspension after the treatment is 4 or more and 7 or less. PH of liquid before and after treatment
Is less than 4, the effect of the alkali treatment is not sufficiently exerted, and the dispersant remains in the suspension. Also, pH
If it exceeds 7, the charge stability is rather adversely affected due to the generation of salts due to the neutralization reaction.

Examples of the alkali which can be used in the present invention include hydroxides of alkali metals and alkaline earth metals such as Na, K, Ca, Li, Mg and Ba; and hydroxides of transition metals such as Zn, Ag, Pb and Ni. Substances: hydroxides of quaternary ammonium salts such as ammonium salts, alkylammonium salts, and pyridium salts. Preferred examples include NaOH and KOH.

As the binder resin used in the present invention obtained as described above, a vinyl copolymer can be particularly preferably used. Examples of the comonomer for obtaining the copolymer include the following. .

Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-
Phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, p -Styrene such as n-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dotesylstyrene and the like; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene Unsaturated vinylenes such as butadiene; vinyl halides such as vinyl chloride, vinyldene chloride, vinyl bromide, and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methyl methacrylate, methacrylic acid Ethyl acrylate, propyl methacrylate, n-butyl methacrylate, methacrylic acid Isobutyl, methacrylic acid n
-Octyl, dodecyl methacrylate, methacrylic acid 2-
Α-methylene aliphatic monocarboxylic esters such as ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate Acrylates such as propyl acrylate, n-octyl acrylate, dotesyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate and phenyl acrylate;
Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole;
N-vinyl carbazole, N-vinyl indole, N-
Vinyl monomers such as N-vinyl compounds such as vinylpyrrolidone; vinyl naphnalines; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide are used alone or in combination of two or more.

Among these, a combination of monomers that results in a styrene-based copolymer and a styrene-acrylic copolymer is preferred.

As the crosslinkable monomer, a monomer having two or more polymerizable double bonds is mainly used.

In the suspension polymerization, based on 100 parts by weight of the aqueous solvent,
It is preferred to carry out with 100 parts by weight or less (preferably 10 to 90 parts by weight) of the above-mentioned monomer. As a dispersant that can be used, polyvinyl alcohol, polyvinyl alcohol partially ketone, calcium phosphate and the like are used,
Although there is an appropriate amount depending on the amount of the monomer relative to the aqueous solvent, it is generally used in an amount of 0.05 to 1 part by weight based on 100 parts by weight of the aqueous solvent. The polymerization temperature is suitably from 50 to 95 ° C, but should be appropriately selected depending on the initiator used and the intended polymer. In addition, as the initiator type, any one which is insoluble or hardly soluble in water can be used.For example, benzoyl peroxide, tert-butyl peroxyhexanoate, or the like is used in an amount of 0.5 to 10 based on 100 parts by weight of the monomer. Used in parts by weight.

The vinyl copolymer used in the present invention needs to be a polymer cross-linked with a cross-linkable monomer as exemplified below in order to achieve the object of the present invention.

Aromatic divinyl compounds, for example, divinylbenzene,
Divinylnaphthalene and the like; diacrylate compounds linked by an alkyl chain, for example, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4
-Butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of the above compounds replaced with methacrylates; alkyl chains containing ether linkages Diacrylate compounds, such as diethylene glycol diacrylate, triethyl glycol diacrylate,
Tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds replaced with methacrylate; with a chain containing an aromatic group and an ether bond Tied diacrylate compounds, for example, polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) Propane diacrylate, and those obtained by replacing the acrylate of the above compound with methacrylate;
Polyester type diacrylate compounds, for example, trade name MANDA (Nippon Kayaku) are listed. Examples of the multifunctional crosslinking agent include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate, and those obtained by replacing the acrylate of the above compound with methacrylate; Allyl cyanurate, triallyl trimellitate; and the like.

These crosslinking agents are preferably used in an amount of about 0.01 to 5 parts (more preferably, about 0.03 to 3 parts) based on 100 parts of the other monomer components.

Among these crosslinkable monomers, aromatic divinyl compounds (particularly divinylbenzene) are preferably used for toner resins in terms of fixability and offset resistance.
Examples include diacrylate compounds linked by a chain containing an aromatic group and an ether bond.

To the toner of the present invention, it is possible to add a charge control agent for imparting charging ability to the toner.

Today, charge control agents known in the art include:

The following substances control the toner to be negatively charged.

For example, an organometallic complex, a chelate compound is effective and a monoazo metal complex as described above, an acetylacetone metal complex,
There are aromatic hydroxycarboxylic acid and aromatic dicarboxylic acid-based metal complexes. On the other hand, aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts, anhydrides and esters thereof. Phenol derivatives such as bisphenol.

The following substances control the toner to be positively charged.

Modified products such as nigrosine and fatty acid metal salts. Onium salts such as quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfanate and tetrabutylammonium tetrafluoroborate, and analogs thereof such as phosphonium salts and lake pigments thereof. Triphenylmethane dyes and their lake pigments. (Examples of lakening agents include phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide) metal salts of higher fatty acids, acetylacetone metal complexes; dibutyltin oxide And diorganotin oxides such as dioctyltin oxide and dicyclohexyltin oxide. Diorganotin borates such as dibutyl tin borate, dioctyl tin borate and dicyclohexyl tin borate. These can be used alone or in combination of two or more.
Among these, charge control agents such as nigrosine and quaternary ammonium salts are particularly preferably used.

Among the charge control agents exemplified above, when an organometallic complex rich in vaporizability or sublimation such as an azo metal complex or an acetylacetone metal complex is used, in addition to the charge controllability, for example, a resin binder during melt kneading. A cross-linking reaction occurs with the carboxylic acid group therein, and as a result, there is an advantage that the offset resistance and the blocking resistance of the toner can be improved.

In the toner of the present invention, it is preferable to add fine silica powder in order to improve charging stability, developability, fluidity, and durability.

The silica fine powder used in the present invention has a specific surface area by nitrogen adsorption measured by the BET method of 30 m ² / g or more (particularly 50 to 400 m
² / g) gives good results. Toner 100
It is preferable to use 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight of silica fine powder based on parts by weight.

Also, the silica fine powder used in the present invention, if necessary,
Silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having functional groups, and other treating agents such as organosilicon compounds for the purpose of hydrophobicity, charge control, etc. , Or in combination with various treating agents.

As other additives, for example, lubricants such as Teflon, zinc stearate, and polyvinylidene fluoride are preferable, and polyvinylidene fluoride is particularly preferable. Alternatively, abrasives such as cerium oxide, silicon carbide, and strontium titanate, among which strontium titanate is preferable. Alternatively, for example, a fluidity-imparting agent such as titanium oxide and aluminum oxide, particularly a hydrophobic agent is preferable. Casing inhibitors or, for example, carbon black, zinc oxide, antimony oxide,
A small amount of a conductivity-imparting agent such as tin oxide or white and black fine particles of opposite polarity can also be used as a developability improver.

For the purpose of improving the releasability at the time of fixing with a hot roll, a wax-like substance such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax, carnauba wax, sasol wax, paraffin hooks, etc. Addition of about 10% by weight to the toner is also a preferred embodiment of the present invention.

Further, when used as a two-component developer, the toner of the present invention is used by mixing with a carrier powder. In this case, the mixing ratio of the toner and the carrier powder is 0.1 to 50% by weight, preferably 0.5 to 10% by weight, more preferably 3 to 5% by weight as the toner concentration.

As the carrier that can be used in the present invention, all known carriers can be used, for example, iron powder, ferrite powder, powder having magnetism such as nickel powder, glass beads, and the like, and the surfaces thereof are fluororesin, vinyl And those treated with a silicone resin or a silicone resin.

Further, the toner of the present invention can be used as a magnetic toner by further containing a magnetic material. In this case, the magnetic material also serves as a colorant. Examples of the magnetic material contained in the magnetic toner of the present invention include iron oxides such as magnetite, hematite, and ferrite; metals such as iron, cobalt, and nickel; and aluminum, cobalt, and copper of these metals.
Examples include alloys of metals such as lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

These ferromagnetic substances preferably have an average particle size of about 0.1 to 2 μm, preferably about 0.1 to 0.5 μm. The amount of the ferromagnetic substance contained in the toner is preferably about 20 to 200 parts by weight per 100 parts by weight of the resin component.
Parts by weight, particularly preferably 40 to 1 to 100 parts by weight of the resin component.
50 parts by weight is good.

In addition, the magnetic characteristics when 10 Ke is applied have a coercive force of 20 to 150 e.
Desirably, the saturation magnetization is 50 to 200 emu / g and the residual magnetization is 2 to 20 emu / g.

The coloring agent that can be used in the toner of the present invention includes any appropriate pigment or dye. Toner colorants are well known and include pigments such as carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary and sufficient to maintain the optical density of the fixed image, and 0.1 to 20 parts by weight, preferably 2 to 10 parts by weight, per 100 parts by weight of the resin is good. Dyes can be used for the same purpose.
For example, there are azo dyes, anthraquinone dyes, xanthene dyes, methine dyes, etc.
The addition amount of 0.1 to 20 parts by weight, preferably 0.3 to 3 parts by weight is good.

To prepare the toner for developing an electrostatic image according to the present invention, a binder resin, a metal compound, a pigment as a coloring agent or a dye, a magnetic substance, a charge control agent, if necessary, and other additives are added to a Henschel mixer. , Kneading and kneading using a hot kneading machine such as a heating roll, kneader, extruder, etc. ,
The toner according to the present invention can be obtained by dispersing or dissolving the dye and the magnetic substance, and solidifying by cooling, followed by pulverization and classification.

Further, if necessary, desired additives are sufficiently mixed with a mixer such as a Henschel mixer to obtain the electrostatic image developing toner according to the present invention.

[Examples] Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited thereto. Hereinafter, parts means parts by weight.

Synthesis Example 1 The above components were suspended and dispersed in 300 parts of water in which 0.6 part of polyvinyl alcohol was dissolved, and polymerized at a polymerization temperature of 75 ° C. for 17 hours to obtain a pearl-shaped resin composition containing a gel component. At this time, the pH of the suspension was 3.7. Next, 0.7 parts of a 7.7 N aqueous sodium hydroxide solution was added to the suspension, and the mixture was stirred for 3 hours. At this time, the pH of the suspension was 5.0.
After alkali treatment, excess, washing with water and drying are performed to obtain a resin composition-1.
I got

Synthesis Example 2 Synthesis Example 1 was the same as Synthesis Example 1 except that 2-ethylhexyl acrylate was used instead of n-butyl acrylate.
In the same manner as in the above, a resin composition-2 was obtained. Akkari processing whole
The pH was 3.6 and 4.9 after treatment.

Synthesis Example 3 In Synthesis Example 1, 0.8 part of a partially saponified polyvinyl alcohol was used instead of polyvinyl alcohol as a dispersant.
A resin composition-3 was obtained in the same manner as in Synthesis Example 1 except that the amount by weight was added. PH before Akkari treatment is 3.7, after treatment 4.8
Met.

Synthesis Example 4 Resin composition-4 was obtained in the same manner as in Synthesis Example 1 except that 1% by weight of a 12N aqueous solution of potassium hydroxide was added instead of the aqueous solution of sodium hydroxide. The pH of the suspension before the alkali treatment was 3.6, and the pH after the treatment was 6.0.

Example 1 After pre-mixing each of the above components with a Henschel mixer,
Melt kneading was performed at 130 ° C. using a twin-screw kneading extruder.
After allowing the kneaded material to cool, coarsely pulverized with a cutter mill, pulverized with a fine pulverizer using a jet stream, and further classified using an air classifier, the black fine powder having a volume average particle size of 0.9 μm ( Toner).

With respect to 100 parts of the toner, hydrophobic colloidal silica 0.4
Was dry-mixed with a Henschel mixer to obtain a developer.

Using this developer, image evaluation was performed in a low-temperature, low-humidity environment (15 ° C., 10% RH) using a Canon copier NP-8580. As a result, the obtained reflection image density was 1.35, and no density change was observed even after copying 200,000 sheets. Fixation,
There were no problems with offset resistance and blacking resistance.

Example 2 A developer was obtained in the same manner as in Example 1 except that the resin composition-2 was used instead of the resin composition-1.

This developer was used in a low-temperature, low-humidity (15 ° C, 10% RH) environment and high-temperature, high-humidity (30 ° C, 30 ° C) using a Canon copier NP-7550.
When the developing property was observed under the environment of 85% RH), the density was high under any of the environments, and a good image quality was maintained even after 200,000 sheets were run, and the density did not decrease.

Example 3 With the above formulation, a developer was obtained in the same manner as in Example 1. The developer was used in a Canon copier NP-5540 in Example 1
The same evaluation was performed. As a result, the image density at the start was 1.30, and there was no change in the density even after 200,000 sheets were run, and the level was satisfactory with the offset and the fixability.

Example 4 With the above formulation, a toner was obtained in the same manner as in Example 1. To 8 parts of this toner, 100 parts of a ferrite carrier whose surface was coated with a fluororesin was mixed to prepare a developer. When this developer was evaluated in the same manner as in Example 2 using a Canon copier NP-6650, it was confirmed that the developer exhibited good developability without environmental dependency.

Example 5 With the above formulation, a fine blue powder (toner) was obtained in the same manner as in Example 1. For 10 parts of this toner, a ferrite carrier coated on the surface with a fluororesin (particle size of about 80μ)
m) 100 parts were mixed to obtain a developer. NP-5
When the same evaluation as in Example 1 was performed using 540,
Good image quality without fog was maintained throughout, and there was no density change at all.

Comparative Example 1 A toner was produced in the same manner as in Synthesis Example 1 except that alkali treatment was not performed after completion of the polymerization. Image evaluation was performed in the same manner as in Example 1. In a normal temperature and normal humidity environment (23 ° C, 60% RH), high image density was maintained throughout, but in a low temperature and low humidity environment, it was 1.35 at the start, but 5000 sheets: 1.25, 10,000 sheets: 1.
As the durability increased, the density became lower, as in the case of 150,000 sheets: 1.00, and the image deteriorated accordingly, so the evaluation was interrupted at the point of 20,000 sheets. Further, the anti-blocking property and anti-offset property were separately examined, and it was confirmed that the anti-blocking property was inferior to that of the developer obtained in Example 1.

Comparative Example 2 A toner was manufactured in the same manner as in Example 1 except that monobutyl maleate was not used in Synthesis Example 1. The same evaluation as in Example 1 was carried out. As a result, although the image density was stable, the fixing property, the anti-offset property and the anti-blocking property were poor, and were not at a level that could be used.

[Effects of the Invention] When the toner obtained by the present invention is used, problems related to the conventional toners are remarkably improved. Especially,
The developability in a low-temperature and low-humidity environment, which has been a problem so far, has been dramatically improved.

That is, the suspension polymerization method is most suitable as the method for producing the resin binder for the toner from the above description, but in the synthesis method, a dispersant is added to uniformly disperse the constituent monomers in the suspension. . However, this dispersant takes an array toward the polymer resin particles, particularly the acid groups present near the surface, and is taken out while adhering to the resin particles. When this resin is converted to a toner as it is, developability and chargeability particularly in a low-temperature and low-humidity environment deteriorate. In order to prevent this, after the polymerization was completed, a small amount of an aqueous alkali solution was added, and the resin obtained by treating the suspension was used as a toner binder, thereby improving the developability and chargeability.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kuniko Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masaki Uchiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-59-152453 (JP, A) JP-A-63-247759 (JP, A) JP-A-63-53563 (JP, A) JP-A-1-244471 (JP, A A)

Claims (10)

(57) [Claims] Claims: 1. A toner for developing an electrostatic image, which is produced through a step of melt-kneading at least a binder resin and a colorant and contains at least the binder resin and the colorant, wherein the binder resin is based on all monomers. 1-30% by weight
A dicarboxylic acid half-ester monomer and another copolymerizable monomer as constituent components, a copolymer synthesized by suspension polymerization using a dispersant, wherein the copolymer is
A toner for developing an electrostatic image, wherein the suspension is subjected to an alkali treatment by treating the suspension after the suspension polymerization with an alkaline aqueous solution. 2. The pH of the suspension after being treated with the alkaline aqueous solution is 4 to 7.
3. The toner for developing an electrostatic image according to item 1. 3. The electrostatic charge image according to claim 1, wherein the copolymer is a nyl copolymer using a vinyl monomer as the other copolymerizable monomer. Development toner. 4. The toner according to claim 3, wherein the vinyl copolymer is a crosslinked polymer synthesized using a crosslinkable monomer. 5. The toner is manufactured through a step of melt-kneading an organometallic compound in addition to the copolymer and the colorant, and contains at least the copolymer, the colorant and the organometallic compound. The toner for developing an electrostatic image according to any one of claims 1 to 4, wherein: 6. A method for producing a toner for developing an electrostatic image, comprising a step of melt-kneading at least a binder resin and a colorant, and a step of pulverizing the obtained kneaded product, wherein 1 to 30% by weight of all monomers % Of a dicarboxylic acid half-ester monomer and another copolymerizable monomer, a copolymer is synthesized by suspension polymerization using a dispersant, and the suspension after completion of the suspension polymerization is made alkaline. A method for producing a toner for developing an electrostatic image, wherein the alkali-treated copolymer obtained by treating with an aqueous solution is used as the binder resin. 7. The pH of the suspension after being treated with the alkaline aqueous solution is 4 to 7.
3. The method for producing a toner for developing an electrostatic image according to item 1. 8. The electrostatic charge image according to claim 6, wherein said copolymer is a vinyl copolymer using a vinyl monomer as said another copolymerizable monomer. A method for producing a developing toner. 9. The method according to claim 8, wherein the vinyl copolymer is a crosslinked polymer synthesized using a crosslinkable monomer. 10. The toner is manufactured through a step of melt-kneading an organometallic compound in addition to the copolymer and the colorant, and contains at least the copolymer, the colorant and the organometallic compound. 10. The method according to claim 6, wherein:
The method for producing a toner for developing electrostatic images according to any one of the above.