JP3104233B2 - Electrophotographic toner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toner. More specifically, the present invention relates to a toner used as a developer in an electrophotographic copying machine, a laser printer, and the like.

(Prior art) In general, the electrophotographic method refers to an inorganic type such as selenium, amorphous silicon, zinc oxide, or a diazo compound,
Organics such as pigments (often processed into drums)
A photoconductive substance (photosensitive drum) is first uniformly charged, and then irradiated with image-modulated light to form an electrostatic latent image, and powder is attached to the electrostatic latent image by electrostatic force After the development, the powder is transferred onto a base material such as paper or film as required, and then fixed by a method such as pressure and heating. The electrophotographic system is currently widely used in copiers, laser printers and the like.

In the electrophotographic system, a powder that develops an electrostatic latent image on a photosensitive drum and that is finally transferred to a base material such as paper or film to form an image is referred to as 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.

Conventionally, as a toner used in an electrophotographic developer, a colorant, a charge control agent, a fluidity modifier, a grinding aid, and the like are added to a thermoplastic resin, kneaded, and then pulverized and further classified. Particles made by the method have been used. Alternatively, in recent years, studies on toners by an emulsion polymerization method, a suspension polymerization method, a seed polymerization method, and the like have been partially performed.

These toners are required to have various physical or chemical properties.

As described above, the image copying process in the electrophotographic system is a repetition of electrostatic transfer of charged toner. Therefore, there are many requirements for the charging characteristics of the toner. Various methods have been proposed and put to practical use for imparting electric charge to the toner. In many cases, however, friction with carrier particles (: carrier), which constitutes a developer by mixing together, has been proposed. Is generally used. In this case, it is desirable that the charge amount of the toner be a constant value regardless of the degree of friction and time. Because, when the charge amount of the toner changes, the amount of the toner attached on the electrostatic latent image on the photosensitive drum changes.
This is because the density of the copied image fluctuates.

In order to quickly perform frictional charging with carrier particles (: carrier), prompt transfer to an electrostatic latent image on a photosensitive drum or from a photosensitive drum to a substrate such as paper or film is performed. To this end, it is, of course, necessary for the toner to exhibit good fluidity.

The electrostatic latent image on the photosensitive drum and the toner are combined by electrostatic force. Therefore, when transferring from the photosensitive drum to a base material such as paper or film, a bias voltage may be applied to the base material side. It is necessary that the substrate and the toner have insulating properties enough to withstand this voltage. In many cases, paper used as a base material has its insulating property greatly reduced due to humidity. Therefore, this insulating property is practically solely carried out by the toner.

The toner transferred onto the base material is fixed by heating or pressing. The heated or pressurized toner must be quickly melted or plastically deformed and adhere to the substrate. At this time, the quality of the image must not be degraded due to an unnecessary decrease in viscosity. At the same time, it should not adhere to the fixing roll side.

The characteristics required for these toners described above are as follows:
Of course, it should not change over long periods of storage or repeated use.
Even after the image is copied, the image quality must be maintained for a long period of time. There must be no transfer, transfer, etc. to another.

When a color image is copied, it is necessary to align toners of the three primary colors of subtractive color mixing, cyan, magenta, and yellow. Each of these color toners is required to have a predetermined reflection spectral characteristic and color reproducibility when color superposition is performed, similarly to the process ink for printing. These color toners also need to have excellent spectral transmission characteristics in preparation for the case where an image is observed by copying the image on a transparent film and projecting the image on a screen using an overhead projector or the like.

In recent years, in order to improve the quality of a copied image, there is a tendency that a smaller particle size and a sharper particle size distribution are required for a toner.

Furthermore, these toners that form the copied image itself are
It is out of the question that it contains toxic substances that cause harm to the human body and impair health, and it is needless to say that it is necessary to have sufficient safety and hygiene.

(Problems to be Solved by the Invention) The characteristics and the like required of the toner have been described above. However, the conventionally used toners do not completely satisfy them.

In many toners, in repeated development by continuous use, the density of the image obtained by the collision between the toner and the carrier particles and the mutual deterioration of the toner, the carrier particles and the photosensitive drum surface due to the contact between the particles and the photosensitive drum surface changes Or the background density increases and the image quality deteriorates.

If an attempt is made to increase the density of a copied image by increasing the amount of toner adhering on the electrostatic latent image on the photosensitive drum, the background density generally increases, that is, so-called fogging occurs.

When transferring a toner from an electrostatic latent image on a photosensitive drum to a base material such as paper by applying a bias voltage, the toner has a sufficient insulating property, particularly in a situation where the insulating property of the base material is reduced due to the influence of humidity. As a result, a discharge occurs between the photosensitive drum and the photosensitive drum, the charge on the photosensitive drum is neutralized, and the electrostatic latent image is destroyed, and the toner attached to the electrostatic latent image is scattered. As a result, the quality of the copied image may be significantly reduced (so-called white spots).

For fixing a toner transferred onto a base such as paper or film, it is necessary to control the softening temperature of the toner, more specifically, to strictly control the relationship between the temperature and the melt viscosity. More specifically, it functions as a solid up to the fixing temperature, and immediately melts at a predetermined fixing temperature,
So-called sharp melt characteristics are required,
It is difficult to achieve this, and at present, fixing is performed at a considerably high temperature.

In addition, there is too much priority on the fixability to the base, so that there is no adhesion to the fixing roll. In many cases, measures are taken to solve this problem, such as applying a release aid such as silicone oil to the fixing roll. In that case, conversely, adhesion of the release aid to the base becomes a problem.
In addition, maintenance of the apparatus is troublesome, such as replenishment of a mold release aid at regular intervals.

Many toners having a low softening temperature tend to agglomerate during handling or storage due to the property of being easily melted by heat, and the fluidity is significantly deteriorated, especially during long-term storage. Further, the frictional charging property and the flow characteristics of many toners are deteriorated due to the influence of the temperature and humidity of the environment.

For toners of smaller particle size, which have been strongly demanded in recent years in order to improve the quality of copied images, further problems in manufacturing cannot be excluded from the discussion. That is, it is difficult to industrially obtain particles having an average particle diameter of about 10 μm or less by a pulverization method which has been regarded as a method for producing a toner in many cases. If you just pulverize the resin itself, with the current pulverizer,
Obtaining particles of 10 μm or less is not so difficult.
However, since not all of the pulverized particles have the desired particle size, an operation of classifying is naturally involved. This means that the fractionation drops very much. Further, in the case of producing a fine particle size toner by a pulverization method, a coloring agent, a charge control agent, a fluidity modifier, a pulverization auxiliary agent, and the like to be added to the thermoplastic resin as a main component are required in advance. It must be ground to a particle size smaller than the particle size, and a significant increase in production cost cannot be avoided. These reasons make it difficult to industrially manufacture a toner having a fine particle diameter by a pulverization method.

As a matter of course, the shape of the toner obtained by the pulverization method is irregular, and only a toner having a broad particle size distribution can be obtained.

In recent years, some studies on toners by emulsion polymerization, suspension polymerization, seed polymerization, etc. have been conducted with the purpose of addressing the problems of the pulverization method described above. is there. The particles obtained by the polymerization method are excellent in fluidity because the shape is spherical, so that uniform triboelectric charging can be expected, and furthermore, by appropriately controlling the polymerization, the heat melting property can be controlled.
And other excellent properties can be expected.

In the emulsion polymerization method, polymerization is carried out in micelles of a polymerizable monomer stabilized with a surfactant in water to obtain a fine particle powder. In the emulsion polymerization method, particles having a sharp particle size distribution can be obtained. However, since the particle size is determined by the size of the micelles that can exist stably, the particle size is about 0.01 to 0.5 μm
m, and it is difficult to produce particles having a particle size of about 1 μm or more. Since the particle size required for the toner is limited to approximately several μm to several tens μm, the particles obtained by the emulsion polymerization method cannot be used as it is for the toner for electrophotography. Further, when a surfactant which is essential for stabilizing micelles remains on the particle surface, it may affect the fluidity or charging characteristics of the particles.

The suspension polymerization method is a method of polymerizing a polymerizable monomer in a suspension obtained by stirring water and a polymerizable monomer to obtain particles. In the suspension polymerization method, polymerization in a stable system is not easy, and it is technically difficult to obtain fine polymer particles having a uniform particle size distribution by polymerization. The reason for this is that particles coalesce during granulation. To prevent coalescence of particles and stabilize polymerization,
For example, in suspension polymerization, when polymerizing a polymerizable monomer in an aqueous dispersion, a suspension stabilizer is used to prevent coalescence of particles as the polymerization proceeds. As the suspension stabilizer, generally, a poorly soluble inorganic compound, for example,
Barium sulfate, calcium sulfate, magnesium carbonate, barium carbonate, calcium carbonate, poorly soluble salts such as calcium phosphate, silica, calcia, magnesia, metal oxides such as titanium oxide, minerals such as diatomaceous earth, chlorophyll, clay, kaolin, and the like Mixtures, etc., or water-soluble mixtures,
For example, polyvinyl alcohol, gelatin, starch and the like are used. Since these suspension stabilizers are known to adversely affect the charging characteristics of the particles when remaining on the particle surface, washing or the like is essential after obtaining the polymerized particles. Is very difficult. Actually, even when these suspension stabilizers are used, the particle size range of the particles obtained by the suspension polymerization method is about several tens μm.
As described above, and the particle size distribution becomes broad, it is difficult to obtain a particle size in the range of approximately several μm to several tens of μm required for the toner for electrophotography.

Seed polymerization is a polymerization method proposed to solve these problems. In the seed polymerization method, for example, particles obtained by another method such as an emulsion polymerization method are used as seed particles, the seed particles are expanded with a solvent and a polymerizable monomer, and polymerization is performed in the expanded seed particles. Is a method of growing seed particles to a large size. In the seed polymerization method, by selecting appropriate seed particles, particles having a sharp particle size distribution can be obtained. The particle size of the particles can be controlled by the coefficient of expansion between the seed particles and the polymerizable monomer.

However, the expansion rate of the seed particles cannot be increased unnecessarily. For example, increasing the particle diameter ten times corresponds to increasing the volume one thousand times. When the seed particles are expanded about 1000 times by the polymerizable monomer,
Already, the seed particles cannot maintain their shape as particles and may break down in some cases. That is, the expansion coefficient cannot be made extremely large, and there is naturally a limit on the particle size range in which growth can be performed at once, and at most 2-3
It is about twice. If larger particles are to be grown, seed polymerization must be repeated.

In the seed polymerization, technically, particles having a sharp particle size distribution can be obtained in a particle size range of several μm to several tens μm. However, it is not easy to find suitable particles as seed particles, and the production cost is enormous due to the complexity of the process, and above all, the method for supplying the toner for electrophotography at an industrial level. Can not be.

That is, almost several μs required for electrophotographic toner
It is very difficult to produce particles having a sharp particle size distribution industrially at low cost in the particle size range of m to tens of μm by the conventional polymerization method.

Furthermore, the resin particles obtained by the conventional polymerization method are limited to so-called vinyl resin particles represented by styrene / acrylic resin and the like. In addition, to the resin particles obtained by these polymerization methods, a charge control agent, a coloring agent, an anti-offset agent, a fluidity improver, and the like, which are used to impart many physical properties essential for an electrophotographic toner, are added. It is not easy. That is, at present, even the resin particles obtained by the conventional polymerization method have not yet solved many problems required for the toner.

As described above, the conventional toner has humidity resistance, that is, humidity dependency such as charging characteristics, flow characteristics, and insulation properties, and also has fixing properties, sharp melt properties, offset resistance, particle size distribution, transparency, and color reproduction. This has many problems in terms of properties, production costs and the like.

In view of such circumstances, the present inventors have intensively studied to obtain a toner which can satisfy these many required characteristics comprehensively and can be industrially produced, and as a result, have arrived at the next invention.

(Means for Solving the Problems) That is, the present invention relates to a resin (A) containing a polyester having a softening point of 80 to 150 ° C. and a glass transition point of 40 ° C. or higher as a main component.
Is contained as a base material, and particles having an average particle diameter of 6.5 to 9.2 μm and a sphericity (ratio of major axis to minor axis) of 0.7 or more are present in a number average of 70% or more. An electrophotographic toner, wherein the toner further comprises carbon black
An electrophotographic toner comprising 10% by weight.

The toner according to the present invention is characterized in that particles having a mean particle size of 1 to 30 μm and a sphericity of 0.7 or more are particles having a number average of 70% or more in a specific resin of a polyester main material. However, these particles more preferably have a sharp particle size distribution in which, when the average particle size is D, particles having a particle size falling within a range of 0.5D to 2.0D are present in a number average of 70% or more. Particles.

In the present invention, particles having a sphericity (ratio of major axis to minor axis) of 0.7 or more are substantially spherical with a number average of 70% or more, and the diameter is in the range of 0.5D to 2D when the average particle is D. As a method for obtaining polyester resin particles having a sharp particle size distribution in which particles having a particle size that occupies 70% or more of the whole on average, for example, an aqueous dispersion mainly containing an ionic group-containing polyester is used. An example is a method of producing a vinyl monomer having a counterionic group of the polyester by polymerizing the vinyl monomer at an equivalent ratio of 0.8 to 2.0.

Here, the polyester is not particularly limited, but is preferably a polyester mainly composed of a dicarboxylic acid resin and a glycol component.

Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid and 1,5-naphthalic acid, and aromatic oxycarboxylic acids such as p-oxybenzoic acid p- (hydroxyethoxy) benzoic acid. ,
Aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, hexahydrophthalic acid,
There are unsaturated aliphatic and alicyclic dicarboxylic acids such as tetrahydrophthalic acid.

If necessary, tri- and tetracarboxylic acids such as trimellitic acid, trimesic acid and pyromellitic acid may be contained in small amounts.

Glycol components include, for example, ethylene glycol,
Propylene glycol, 1,3-propanediol, 1,4-
Butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, Spiro glycol, 1,4-phenylene glycol, ethylene oxide adduct of 1,4-phenylene glycol, polyethylene glycol, polypropylene glycol, diols such as polytetramethylene glycol,
There are ethylene oxide adduct and propylene oxide adduct of bisphenol A, and ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A.

If necessary, a small amount of triol and tetraol such as trimethylolethane, trimethylolpropane, glycerin and pentaerthritol may be contained.

Other examples of the polyester polyol include lactone-based polyester polyols obtained by ring-opening polymerization of a lactone such as ε-caprolactone.

The ionic group contained in the polyester includes an anionic group such as a carboxyl group, a sulfonic acid group, a sulfate group, a phosphate group, or a salt thereof, or a primary to tertiary group.
A cationic group such as a tertiary amine group, and preferably sulfonic acid and / or a metal base thereof.

As the sulfonic acid copolymerizable with the polyester and or the aromatic dicarboxylic acid containing the metal base thereof, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid,
5 [4-sulfophenoxy] isophthalic acid and the like and / or metal salts thereof can be mentioned. L as metal salt
Salts of i, Na, K, Mg, Ca, Cu, Fe and the like can be mentioned. Particularly preferred is 5-sodium sulfoisophthalic acid.

The amount of the aromatic dicarboxylic acid containing a sulfonic acid metal base is not limited as long as the dispersion, preferably an aqueous dispersion, can be obtained. However, the amount is preferably in the range of 20 to 500 equivalents / 100,000 g.

In the present invention, the polyesters can be used alone or in combination of two or more as needed. Also, the molten state,
In a solution state, it can be mixed with an amino resin, an epoxy resin isocyanate compound or the like, and furthermore, it can be partially reacted with these compounds. The obtained partial reaction product can be similarly used as a raw material for an aqueous dispersion.

The aqueous dispersion containing the ionic group-containing polyester of the present invention as a main component can be produced by any known method. That is, by pre-mixing the polyester and the water-soluble organic compound at 50 to 200 ° C. and adding water thereto, or adding a mixture of the polyester and the water-soluble organic compound to water and stirring at 40 to 120 ° C. Manufactured. Alternatively, it is also produced by a method in which a polyester is added to a mixed solution of water and a water-soluble organic compound, and the mixture is stirred at 40 to 100 ° C. and dispersed.

The “vinyl monomer containing a counter ionic group” in the present invention refers to an ionic group opposite to the ionic group contained in the polyester (a counter ionic group in which the ionic group contained in the polyester is an anionic group). Means a vinyl monomer having a cationic group, or a counterionic group having an anionic group when the ionic group contained in the polyester is a cationic group. Such ionic groups are preferred for forming a stable aqueous dispersion of the polyester.

The amount of the counter ionic group is based on the amount of the ionic group in the polyester, and the amount of the counter ionic group in the polymer obtained by polymerizing the vinyl polymerizable monomer is equivalent to 0.8 to 2.0, preferably 0.85. It is in the range of ~ 1.5. When the value is less than the lower limit of the range, coalescence of the fine particles and growth hardly occur,
In addition, exceeding the upper limit may not only contribute to the growth of the fine particles but also cause inconveniences such as a decrease in the water resistance of the resin particles.

As the cationic group-containing vinyl monomer, for example,
2-aminoethyl (meth) acrylate, 2-N, N-dimethylaminoethyl (meth) acrylate, 2-N, N-
Diethylaminoethyl (meth) acrylate, 2-N, N
-Dipropylamino (meth) acrylate, 2N, t-butylaminoethyl (meth) acrylate, 2- (4-morpholino) -ethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, aminostyrene and the like. Can be

Examples of the anionic group-containing vinyl monomer include monomers containing a carboxyl group such as (meth) acrylic acid, itaconic acid, frotonic acid, maleic acid, and fumaric acid or salts thereof, styrenesulfonic acid, vinyltoluenesulfonic acid, and vinyl. Ethylbenzenesulfonic acid, isopropenylbenzenesulfonic acid, 2-chlorostyrenesulfonic acid, 2-methyl-4-chlorostyrenesulfonic acid, vinyloxybenzenesulfonic acid, vinylsulfonic acid,
Azidophosphoxyethyl, a monomer containing a sulfonic acid group or a disa salt, such as (meth) allylsulfonic acid, sulfoethyl or (meth) acrylic acid sulfoethyl ester, or 2-acrylamido-2-methylpropanesulfonic acid; Monomers containing a phosphate group or a salt thereof such as (meth) acrylate, azidophosphoxypropyl (meth) acrylate 3-chloro-2-azidophosphoxypropyl methacrylate, bis (meth) acryloxyethyl phosphate, and vinyl phosphate can give.

In order to achieve the object of the present invention, a combination of an anionic group-containing polyester and a cation group-containing vinyl monomer is more preferable. In addition, a known nonionic monomer may be appropriately used.

There is no particular limitation on the polymerization initiator used when polymerizing the vinyl monomer, and examples thereof include benzoyl peroxide, organic peroxides such as acetyl peroxide, 2,2′-azobisisobutyronitrile, and 2,2′-. Azo compounds such as azobis (2,4-dimethylvaleronitrile); inorganic peroxides such as persulfates, hydrogen peroxide and permanganate; inorganic peroxides and sulfites, bisulfites and metasulfites And a water-soluble redox initiator with a reducing agent such as hydrosulfite, thiosulfate, iron salt, acid and the like. From the viewpoint of safety and industrial use, a water-soluble redox initiator is preferable. The amount of the polymerizable initiator used is generally in the range of 0.1 to 3% by weight based on the vinyl monomer.

Although it is difficult to unambiguously define the polymerization temperature, the polyester fine particles dispersed in an aqueous medium are combined with the polymerization of the vinyl monomer and grown into a spherical shape. It is desirable to employ the temperature condition described below. Under the condition below the temperature, amorphous particles are likely to be generated. By using a polyester solvent and a plasticizer together, the apparent glass transition point (or the minimum film forming temperature) of the polyester is lowered,
Polymerization can be carried out under the conditions above such temperature. The type of the solvent or the plasticizer is not limited, and is appropriately selected from known ones according to the type of the polyester as long as the polymerization is not inhibited.

Other polymerization conditions are carried out according to a conventional method, but a method of previously charging a vinyl monomer into an aqueous dispersion of polyester fine particles and then dropping a polymerization initiator is a problem such as rapid coalescence and aggregation of the polyester fine particles. Is preferred because there is no

The resulting aqueous dispersion of polyester resin particles is taken out as a dry powder according to a conventional method such as filtration, freeze drying, spray drying and the like.

Thus, the toner according to the present invention is a substantially spherical particle having a ratio of the major axis to the minor axis of 0.7 or more, and the particle diameter is in the range of 0.5D to 2D when the average particle diameter is D. Polyester resin particles having a relatively sharp distribution, in which the number of particles occupies 70% or more of the total number, can be produced industrially.

As the carbon black used in the invention,
Thermal black, acetylene black, channel black, furnace black, lamp black and the like can be used. The content of carbon black is 1 to 10% by weight. If the content of carbon black is lower than this, a sufficient image density cannot be obtained in the copied image. If the content exceeds this range, a problem may occur in the fixing property of the toner.

In the present invention, carbon black may be used alone, or may be used in combination as needed. If necessary, other colorants such as pigments and dyes may be used in combination.

In the present invention, the form in which carbon black is contained in the polyester resin particles is not limited. The carbon black may be, for example, adsorbed or coated on the particles, or may be injected into the particle surface by, for example, a mechanofusion method that is a dry process, but may be contained in a form dispersed in the particles. Most preferably.

As a method for producing particles containing carbon black in a form of being dispersed in the particles, in the above-described method for producing polyester-based resin particles, an “aqueous dispersion mainly containing an ionic group-containing polyester” is produced. At this time, a method using "polyester in which carbon black is dispersed" in advance can be exemplified.

The glass transition point of the polyester resin in the present invention is
40 ° C or higher. If the glass transition point is lower than this, there is a tendency to aggregate during handling or storage,
This may cause a problem in storage stability.

The softening point of the polyester resin in the present invention is 80 to 15
It is in the range of 0 ° C. In a toner in which the softening temperature of the resin is kept lower than this, there is a tendency to agglomerate during handling or storage, and especially during long-term storage, the fluidity may be significantly deteriorated. If the softening point is higher than this, the fixability will be 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 base material to be copied are limited.

In the electrophotographic toner of the present invention, a charge control agent may be used to give a stable charge.

Examples of the charge control agent that gives a positive charge to the toner by friction with carrier particles (: carrier) include, for example, titanates such as Ca and Ba, polyamide resins such as carbonate, alkoxylated amine and nylon, phthalocyanine blue, and quinacridone red. , Azo-based metal complex green, pigments having a positive zeta potential represented by, azine-based compounds, stearic acid-modified azine compounds, traic-acid-modified azine compounds, azine-based pigments such as nigrosine,
And quaternary ammonium salt compounds.

Examples of the charge control agent that gives a negative charge to the toner by friction with carrier particles (: carrier) include pigments having a negative zeta potential such as carbon black, halogenated phthalocyanine green, flavanstone yellow, and perylene red; copper; Metal-containing azo compounds such as zinc, lead, and iron are opened.

In the toner of the present invention, a fluidity modifier such as alumina fine particles and silica fine particles may be added. The amount to be added is not particularly limited, but is preferably from the viewpoint of imparting appropriate fluidity to the toner.
It is about 0.01 to 5% by weight, more preferably about 0.1 to 2% by weight.

Toner used without being mixed with carrier particles (: carrier): In the case of a one-component developer, the toner needs to have magnetism. In such cases, iron,
It may contain cobalt, nickel, an alloy mainly containing them, or an oxide such as ferrite.

Colorants, charge control agents, flow modifiers described above,
In the present invention, the method of treating the particles with particles and the like is not particularly limited in the present invention, and a known existing treatment method can be used. These may be, for example, dispersed in the particles, adsorbed on the particles, or coated, or may be driven into the surface of the particles by, for example, a mechanical fusion method as a dry process.

The polyester resin used in the toner of the present invention has no fusing or agglomeration at room temperature, and exhibits good fixability at the time of fixing because the viscosity is promptly reduced.

The toner according to the present invention has a sharp particle size distribution,
In addition, since it is substantially spherical, the reproducibility of a copied image, especially the reproducibility of a fine line, is excellent.

The toner according to the present invention is excellent in physical properties of the polyester resin as a main component thereof, and has excellent moisture resistance such that the charging characteristics and the fluidity do not change even in a severe moist heat environment.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. The physical properties of the resin and the like in the examples and comparative examples were measured by the following methods.

・ Average particle diameter The average particle diameter was measured with an automatic particle size distribution measuring apparatus CAPA700 manufactured by Shimadzu Corporation.

・ Sphericality Measure the major axis and minor axis from the figure of the sphere measured and projected by the optical microscope, measure the sphericity by the ratio of the minor axis to the major axis, and set it as a true sphere at 1.0, and as a deformed sphere at 1.0 or less Judged.

・ Melting point, glass transition point Heating rate by differential scanning calorimeter (manufactured by Shimadzu Corporation)
It was measured at 10 ° C./min.

-Softening point Measured according to JIS K2351.

-Number average molecular weight (vapor pressure method) It was measured with a molecular weight measuring device (manufactured by Hitachi, Ltd.).

Example 1 In an autoclave equipped with a thermometer and a stirrer, 94 parts by weight of dimethyl terephthalate, 95 parts by weight of dimethyl isophthalate, 89 parts by weight of ethylene glycol, 80 parts by weight of neopentyl glycol, and 0.1 part by weight of tetrabutoxy titanate were used. The mixture was heated at 120 to 230 ° C. for 120 minutes to perform a transesterification reaction. Next, 6.7 parts by weight of 5-sodium sulfoisophthalic acid was added, and the reaction was continued at 220 to 230 ° C. for 60 minutes.
After the temperature was raised to ℃, the reaction was continued at a system pressure of 1 to 10 mmHg for 60 minutes, and as a result, a copolymerized polyester (A1) was obtained.

The molecular weight of the obtained copolymerized polyester (A1) is 2700,
The sulfonic acid metal base was 118 equivalents / 100,000 g. The amount of the sulfonic acid metal base was determined by measuring the sulfur concentration in the copolymerized polyester. In addition, copolymerized polyester (A1)
As a result of NMR analysis, the composition of terephthalic acid 48.5 mol%, isophthalic acid 49.0 mol%, 5-sodium sulfoisophthalic acid 2.5 mol% as an acid component, ethylene glycol 61.0 mol%, neopentyl glycol 39.0 mol% as an alcohol component Met.

What was obtained by coarsely pulverizing the obtained copolyester (A1)
100 parts by weight and carbon black (F-Tex-8,
5 parts by weight of Cabot Corporation) were mixed with a ball mill and pulverized, and then melt-mixed with a roll mill to obtain a carbon black-containing copolyester (colored copolyester) (B1).
I got

4-port 1 equipped with thermometer, condenser and stirring blade
After dissolving 34 parts by weight of the obtained colored copolymerized polyester (B1) and 10 parts by weight of butyl cellosolve in a 1-liter separable flask at 110 ° C., 56 parts by weight of water at 80 ° C. are added, and an aqueous system of the colored copolymerized polyester is added. A dispersion (C1) was obtained.

4-port 1 equipped with thermometer, condenser and stirring blade
A liter separable flask was charged with 834 parts by weight of the copolymerized polyester aqueous dispersion (C1), 35 parts by weight of deionized water, and 5.6 parts by weight of dimethylaminoethyl methacrylate, and heated to 70 ° C. Next, 100 parts by weight of an aqueous solution containing 0.2 parts by weight of ammonium persulfate was added dropwise over 40 minutes, and the reaction was continued for another 60 minutes at 70 ° C.
As a result, the copolymer having a submicron order particle size present in the copolymerized polyester aqueous dispersion grew,
When the average particle diameter is 9.2 μm and the diameter is D, the occupancy (number) of particles having a particle diameter in the range of 0.5D to 2D is 89%, and the sphericity is 0.
Colored polyester resin particles having 90% or more of 7 or more particles, that is, an electrophotographic toner (D1) were obtained.

5 parts by weight of each of the obtained toners was mixed with 95 parts by weight of a carrier (spherical reduced iron powder having an average particle diameter of 80 μm) to obtain a two-component electrophotographic developer. The charge amount of the toner after mixing with the carrier was −35 μC / g. Using these developers, 5000 continuous copies were made on paper by an electrophotographic color copying machine using amorphous silicon as a photosensitive member. The obtained copy had no fog and no fuzz, and showed a clear and excellent image.

In addition, charging characteristics, flow characteristics, humidity dependency such as insulation,
No particular problems were found in fixing properties, sharp melt properties, anti-offset properties and the like.

[Example 2] Copolyester (A1) obtained in Example 1
100 parts by weight, 5 parts by weight of carbon black (Ftex-8, manufactured by Cabot Corporation) and 31 parts by weight of butyl cellosolve were dissolved at 110 ° C., mixed and dispersed by a homomixer, and then 173 parts by weight of water at 80 ° C. Was added to obtain an aqueous dispersion (C2) of a colored copolymerized polyester.

4-port 1 equipped with thermometer, condenser and stirring blade
A liter separable flask was charged with 834 parts by weight of the copolymerized polyester aqueous dispersion (C2), 35 parts by weight of deionized water, and 5.3 parts by weight of dimethylaminoethyl methacrylate, and heated to 70 ° C. Next, 100 parts by weight of an aqueous solution containing 0.2 parts by weight of ammonium persulfate was added dropwise over 40 minutes, and the reaction was continued for another 60 minutes at 70 ° C.
As a result, the copolymer having a submicron order particle size present in the copolymerized polyester aqueous dispersion grew,
Colored polyester resin particles having an occupancy (number) of 82% of particles having a sphericity of 0.7 or more, an average particle diameter of 6.5 μm, and a particle diameter of 0.5D to 2D where D is a diameter of 82%, ie, electrons. A photographic toner (D2) was obtained.

5 parts by weight of each of the obtained toners was mixed with 95 parts by weight of a carrier (spherical reduced iron powder having an average particle diameter of 80 μm) to obtain a two-component electrophotographic developer. The charge amount of the toner after being mixed with the carrier was -72 μC / g. Using these developers, 5000 continuous copies were made on paper by an electrophotographic color copying machine using amorphous silicon as a photosensitive member. The obtained copy had no fog or callus, showed a clear and good image, and was particularly excellent in reproducing fine lines.

In addition, charging characteristics, flow characteristics, humidity dependency such as insulation,
No particular problems were found in fixing properties, sharp melt properties, anti-offset properties and the like.

[Comparative Example 1] The colored copolymerized polyester (B1) obtained in Example 1 was further pulverized by a Hosokawa-type fine pulverizer and separated into balls to obtain 3
To 20 μm (average particle size: 12 μm) to obtain a toner (D3). The yield was 75%. The obtained toner is mixed with 95 parts by weight of a carrier (spherical reduced iron powder having an average particle diameter of 80 μm),
A two-component electrophotographic developer was obtained. The charge amount of the toner after mixing with the carrier was −18 μC / g.

In the same manner as in Example 1, using these developers, continuous copying of 5,000 sheets was performed on paper by an electrophotographic color copying machine using amorphous silicon as a photosensitive member. The obtained copy had many blurs and a clear image could not be obtained.

[Comparative Example 2] In Comparative Example 1, fine particles were further pulverized with a Hosokawa-type fine pulverizer, separated and classified to 3 to 10 µm (average particle diameter of 7.8 µm) to obtain a toner (D4). The yield was only 20%.
Also, the fluidity was not satisfactory.

The obtained toner was mixed with 95 parts by weight of a carrier (spherical reduced iron powder having an average particle diameter of 80 μm) to obtain a two-component electrophotographic developer. The charge amount of the toner after mixing with the carrier is −31 μC /
g.

Using these developers in the same manner as in Example 1, 5,000 continuous copies were made on paper by an electrophotographic color copying machine using amorphous silicon as a photosensitive member.

The copy obtained fogged from the beginning of the copy. Further, with an increase in the number of copies, the number of tailings and brush marks increases, and after 2,000 copies, it becomes difficult to discriminate images, and copying cannot be substantially continued. Particles were scattered violently inside the copying machine, and the photosensitive drum and the optical system were significantly contaminated.

(Effects of the Invention) As described above, the toner according to the present invention has excellent properties such as sharp particle size distribution, excellent fixability, excellent offset resistance, and low production cost. Further, the toner according to the present invention provides an image having particularly excellent reproducibility of copying fine lines due to its sharp particle size distribution.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/087-9/09

Claims (2)

(57) [Claims] 1. A softening point of 80 to 150 ° C. and a glass transition point of 40 ° C.
Particles containing the resin (A) containing the above polyester as a main component as a base material, having an average particle size of 6.5 to 9.2 μm, and having a sphericity (ratio of major axis to minor axis) of 0.7 or more are obtained. 70 by number
% Of the toner for electrophotography. 2. An electrophotographic toner according to claim 1, wherein said toner contains 1 to 10% by weight of carbon black.