JPH0943904A - Electrostatic charge image developing toner and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a uniform coated layer with the minimum coating, increase productivity and durability of image quality, and uniform and stabilize electrification at the same time by forming a coated later using polyfunctional organic peroxide polymerization initiator. SOLUTION: In a process where polymer particles with coated layer or toner coated layer is formed, a polyfunctional organic peroxide polymerization initiator is used. As the coated layer becomes thinner, the uniformity of coating on resin particles becomes a more important factor. Therefore, more coating stability can be obtained by the use of the organic peroxide initiator which is provided with at least two or more functional groups. Namely, though the polyfuncticonal organic peroxide polymerization initiator has a property to bind it to a polymerization chain end in the polymerization process, the polymerization initiator has a function to stabilize a forming coated layer at the beginning of the polymerization and, after polymerization, a polymerization chain can also be changed into three dimensional one. Thus the strength of the coated particle surfaces and the uniformity of the surfaces can be increased at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used in a method for developing an electrostatic latent image and a method for producing the toner.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic method, U.S. Pat. No. 2,297,691 and JP-B-42-23910 are known.
Although many methods are known as described in JP-A-43-24748 and JP-A-43-24748, generally, a photoconductive substance is used and an electric latent image is formed on a photoreceptor by various means. After the latent image is formed, the latent image is developed with toner, and the toner image is transferred to a transfer material such as paper, if necessary, and then fixed by heating, pressure, heating pressure, solvent vapor or the like to obtain a copied image. It is a thing.

As a method of developing with toner or a method of fixing a toner image, various methods have been conventionally proposed, and methods suitable for respective image forming processes have been adopted.

Conventionally, the toner used for these purposes is generally a toner having a desired particle diameter by a fine pulverizer and a classifier after melt-mixing a coloring agent consisting of a dye and a pigment in a thermoplastic resin and uniformly dispersing them. Has been manufactured.

While this method of manufacture can produce fairly good toners, it does have certain limitations, ie, the choice of toner materials. For example, the resin colorant dispersion must be sufficiently brittle and capable of being pulverized in economically feasible manufacturing equipment. However, if the resin colorant dispersion is made brittle in order to satisfy these requirements, the particle size range of the particles formed when actually pulverized at high speed tends to be wide,
In particular, a problem arises that a relatively large proportion of fine particles is contained in this. Further, such a highly brittle material is susceptible to further pulverization or pulverization when used for development in a copying machine or the like. Further, with this method, it is difficult to disperse solid fine particles such as a colorant into the resin completely and uniformly. Depending on the degree of dispersion, fog increases, image density decreases, and color mixing / transparency Care must be taken in dispersion as it causes defects. Further, exposure of the coloring agent to the fracture surface may cause fluctuations in development characteristics.

On the other hand, in order to overcome the problems of the toner caused by these pulverization methods, Japanese Patent Publication Nos.
JP-A-3-10799 and JP-A-51-14895 have proposed a method for producing a toner by a suspension polymerization method. In the suspension polymerization method, a polymerizable monomer, a colorant,
A polymerization initiator and, if necessary, a cross-linking agent, a charge control agent, and other additives are uniformly dissolved or dispersed to form a monomer composition, and the monomer composition contains a dispersion stabilizer. The particles are dispersed in a continuous phase, for example, an aqueous phase using a suitable stirrer, and a polymerization reaction is simultaneously performed to obtain toner particles having a desired particle size.

Since this method does not include a crushing step at all, the toner does not need to be brittle, a soft material can be used, and the colorant is not exposed on the surface of the particles. It has the advantage of having excellent triboelectric charging properties. Further, since the classification step can be omitted, there are great cost reduction effects such as energy saving, shortening of manufacturing time, and improvement of process yield.

However, in the case of such a polymerization method toner having a fine particle diameter, the colorant is exposed to or close to the toner surface layer as compared with the toner having a large particle diameter, so that the influence of the colorant is likely to occur, and thus the charging uniformity is uniform. It has become clear that

This phenomenon becomes remarkable when the number of printings of the copying machine is repeated under high humidity. Conventionally, in order to make the charging uniform, for example, JP-A-62-73277, JP-A-3-35660, etc., a method of coating a so-called toner surface layer with a resin has been proposed.

However, in these methods, since the coating layer is thick, the influence of the coloring agent can be prevented, but
Since almost no component having charge controllability can be contained, there has been a problem that the absolute value of the charge amount becomes small.

Further, in order to improve this problem, Japanese Patent Laid-Open No. 62-73277, which focuses on mixing a charge control agent into a coating resin layer, considers the durability of the fine particle toner, and therefore, the copying When the number of impressions is repeated, the charge control agent is likely to be exposed on the toner surface as in the case of the colorant.

Therefore, a method of coating the surface of the polymer particles in multiple stages is disclosed in JP-A-64-62666 and JP-A-6-66266.
4-63035, Japanese Patent Publication No. 58-57105, etc., but the manufacturing process is complicated,
It is a cost disadvantage.

Further, in recent years, digital full-color copying machines and printers have been put on the market, and it has become possible to obtain not only resolution and gradation but also high image quality excellent in color reproducibility without color unevenness.

In a digital full-color machine, a color image original is color-separated by B (blue), G (green), and R (red) filters, and then a latent image having a dot diameter of 20 to 70 μm corresponding to the original image. Is developed by utilizing the subtractive color mixing effect with each of the Y (yellow), M (magenta), C (cyan), and Bk (black) developers. It is expected that there will be a need to transfer to a transfer material, and further a demand for a finer particle size of a developer corresponding to a fine dot in order to cope with higher image quality in the future.

Further, in the future as printers and copiers become faster and full-colored, further improvement in low-temperature fixability becomes an important factor. From this point as well, the particle size distribution is sharp and the fine particle size is small. The polymerization methods by which the developer can be produced exhibit excellent properties. Toners mounted on a full-color copying machine are required to sufficiently mix multicolor toners in a fixing process, and it is essential to improve color reproducibility and transparency of OHP images at this time. Further, as the color toner, a resin having a low molecular weight, which has a better melting property than that of the black toner, is usually required.

Further, for the general black toner, a releasing agent having a relatively high crystallinity represented by polyethylene wax or polypropylene wax is used for the purpose of improving the high temperature offset resistance at the time of fixing.

However, in the full-color toner, the crystallinity of the release agent is high, so that the transparency is remarkably hindered when outputting to the OHP.

Therefore, by normally applying silicone oil or the like to the heat fixing roller without adding a releasing agent as a constituent of the color toner, the high temperature offset resistance is improved as a result.

However, the output transfer material thus obtained is not preferable because extra silicone oil or the like adheres to the surface of the output transfer material, causing discomfort when the user handles it.

For this reason, a developer for oilless fixing in which a large amount of a low softening point substance is contained in the developer has been studied, but it has excellent low temperature fixing property and transparency, and at the same time has high temperature offset resistance. No developing agent has been obtained yet.

[0021]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a toner for developing an electrostatic charge image and a method for producing the same, which solves the above-mentioned problems of the prior art.

That is, an object of the present invention is to provide a toner for developing an electrostatic charge image which is excellent in uniform charging property, has less fogging and scattering, has improved stability of charging property in durability and is excellent in manufacturability, and a manufacturing method thereof. To provide.

[0023]

Means and Actions for Solving the Problems The present inventors have
As a result of repeated intensive studies to overcome the problems in the above-mentioned conventional techniques, by using a polyfunctional organic peroxide polymerization initiator in the step of forming polymer particles having a coating layer or a toner coating layer, It has been found that a uniform coating layer is formed, and that uniform charging and improvement of durability can be easily achieved, and the present invention has been completed.

That is, the present invention does not prevent the fine irregularity of the chargeability of the toner surface by thickly coating or adding a charge control agent as in the prior art, but the polyfunctional organic peroxide is used. The present invention has been completed, paying attention to the fact that it is sufficient to make the toner surface uniform by using a physical polymerization initiator with a minimum coating.

It is obvious that the thinner the coating layer is, the more important the uniformity of coating on the resin particles becomes.
The present inventors have examined this point, and at least 2
It has been found that even more coating stability can be obtained by using an organic peroxide-based initiator having three or more functional groups.

That is, the polyfunctional organic peroxide polymerization initiator has a property of being bonded to the polymer chain end in the polymerization process, but the polymerization initiator of the present invention stabilizes the formed coating layer at the initial stage. Since it has a function and the polymer chain can be three-dimensionalized after the polymerization, it has a function of simultaneously amplifying the homogeneity of the strength and surface property of the coated particle surface.

Therefore, the inventors have found that the use of the above-mentioned initiator can further improve the coating strength and stabilize it, and have reached the present invention.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The toner for developing an electrostatic image and the method for producing the same according to the present invention will be described in detail below.

The polymer particles used in the present invention are generally known by emulsion polymerization method, suspension polymerization method, interfacial polymerization method, salting-out polymerization method, association polymerization method, mechanical pulverization method of resin pieces, spray drying method and the like. Any method may be used as long as it is obtained by a method for producing a polymer or resin particles, but an emulsion polymerization method, a suspension polymerization method, an interfacial weight method or the like, which are previously produced in a uniform aqueous medium, may be used. Polymer particles produced by a so-called polymerization method such as a synthetic method, a salting-out polymerization method, an association polymerization method and the like are preferable because the production surface can be simplified.

The polymerizable monomer that can be used in the above polymer particles is a styrene-based monomer such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene or p-ethylstyrene. Body; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate,
Acrylic esters such as n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, Methacrylic acid n-
Butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and other methacrylate esters; other acrylonitrile, Examples thereof include monomers such as methacrylonitrile and acrylamide. These monomers may be used alone or in combination. Among the above-mentioned monomers, it is preferable to use styrene or a styrene derivative alone or in combination with other monomers, from the viewpoints of developing characteristics and durability of the toner.

In the present invention, it is more preferable to add a polymer or copolymer having a polar group as an additive to the above monomer system for polymerization.

Since the polar polymer and copolymer are gathered in the surface layer of the toner particles, they form a kind of shell and give toner particles excellent properties such as blocking resistance, while By internally polymerizing so as to contribute to the improvement of the fixing property with a relatively low molecular weight, it is possible to obtain a toner satisfying the contradictory performances of fixing property and blocking resistance.

The polar polymers and copolymers that can be used in the present invention are shown below.

Polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, copolymers with styrene and unsaturated carboxylic acid esters, nitrile monomers such as acrylonitrile, and chlorides. Halogen-containing monomers such as vinyl, acrylic acid,
Unsaturated carboxylic acids such as methacrylic acid, other unsaturated dibasic acids, unsaturated dibasic acid anhydrides, polymers such as nitro monomers or copolymers with styrene monomers, polyesters, epoxy resins, etc. Is mentioned.

The addition amount of these polar polymers and copolymers is preferably 0.1 to 10% by weight.

As the colorant used in the polymer particles of the present invention, known colorants can be used. Examples thereof include carbon black and iron black, and C.I. I. Direct Red 1, C.I.
I. Direct Red 4, C.I. I. Acid Red 1,
C. I. Basic Red 1, C.I. I. Modant Red 30, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I.
I. Basic Blue 5, C.I. I. Modant Blue 7, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Dyes such as Basic Green 6; Yellow Lead, Cadmium Yellow, Mineral Fast Yellow, Navel Yellow, Naphthol Yellow S, Hansa Yellow G, Permanent Yellow NCG, Tartrazine Lake, Molybdenum Orange, Permanent Orange GTR, Benzidine Orange G, Cadmium Red,
Permanent Red 4R, Watching Red Calcium Salt, Brilliant Carmine 3B, Fast Violet B, Methyl Violet Lake, Navy Blue, Cobalt Blue, Alkali Blue Lake, Victoria Blue Lake,
Quinacridone, Rhodamine Lake, Phthalocyanine Blue, Fast Sky Blue, Pigment Green B,
There are pigments such as malachite green lake and final yellow green G.

In the present invention, since the toner is obtained by using the polymerization method, it is necessary to pay attention to the polymerization inhibitory property and the water phase transfer property of the colorant, and preferably the surface modification, for example, the polymerization inhibitory property is not caused. It is better to give a hydrophobic treatment with a substance.

In particular, since many dyes and carbon blacks have a polymerization inhibiting property, care must be taken when using them.

A preferred method of surface-treating the dye system is a method of polymerizing a polymerizable monomer in the presence of these dyes in advance, and the obtained colored polymer is added to the monomer system. In addition to carbon black, the carbon black may be treated with a substance that reacts with the surface functional groups of carbon black, such as organosiloxane.

When the toner is used as a magnetic toner, it may contain magnetic powder. As such magnetic powder, a substance that is magnetized when placed in a magnetic field is used.
There are powders of ferromagnetic metals such as iron, cobalt and nickel, or compounds such as magnetite and ferrite.

In particular, in the present invention, since a toner is obtained by using a polymerization method, it is necessary to pay attention to the polymerization inhibitory property and the water phase transfer property of the magnetic material.
For example, it is more preferable to perform a hydrophobic treatment with a substance that does not inhibit polymerization.

In the present invention, for the purpose of improving releasability at the time of heat roll fixing, a hydrocarbon compound or the like is added to the polymer particles.
You may mix | blend the low softening point substance generally used as a mold release agent.

The low softening point substance used in the present invention is preferably a compound having a main component maximum peak value measured according to ASTM D3418-8 of 40 to 90 ° C. If the maximum peak is less than 40 ° C., the self-aggregating force of the low softening point substance becomes weak, which is not preferable for full-color toner. On the other hand, if the maximum peak exceeds 90 ° C., the fixing temperature becomes high, and it becomes difficult to appropriately smooth the surface of the fixed image, which is not preferable in terms of color mixing. Further, when the toner is obtained by the direct polymerization method, the temperature of the maximum peak value is high because the granulation and the polymerization are carried out in an aqueous system, so that the low softening point substance mainly precipitates during the granulation and hinders the suspension system. Therefore, it is not preferable.

In measuring the temperature of the maximum peak value of the present invention,
For example, DSC-7 manufactured by PerkinElmer is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the heat quantity correction uses the heat of fusion of indium. For the sample, an aluminum pan was used and an empty pan was set as a control, and the temperature rising rate was 10 ° C./min. Perform the measurement with.

Specifically, paraffin wax, polyolefin wax, Fischer-Tropish wax,
Amide wax, higher fatty acid, ester wax and their derivatives or their graft / block compounds can be used. Particularly, in the present invention, an ester wax having one or more long-chain ester moieties having 10 or more carbon atoms represented by the following general structural formula has an effect on high temperature offset resistance without impairing transparency of OHP. preferable. The structural formulas of typical compounds of specific ester waxes preferable in the present invention are shown below as general structural formulas, general structural formulas and general structural formulas.

[0046]

Embedded image

[In the formula, a and b represent an integer of 0 to 4,
a + b is 4, R ₁ and R ₂ represent an organic group having 1 to 40 carbon atoms, and a group having a carbon number difference between R ₁ and R ₂ of 10 or more, and n and m are 0 to 0. Indicates an integer of 15, n and m
Cannot be 0 at the same time. ]

[0048]

Embedded image

[In the formula, a and b represent an integer of 0 to 4,
a + b is 4, R ₁ represents an organic group having 1 to 40 carbon atoms, n and m represent integers of 0 to 15, and n and m do not become 0 at the same time. ]

[0050]

Embedded image

[In the formula, a and b represent an integer of 0 to 3,
a + b is 3 or less, and R ₁ and R ₂ have 1 to 40 carbon atoms
And an organic group having a carbon number difference of 10 or more between R ₁ and R ₂ , R ₃ is an organic group having 1 or more carbon atoms, and n and m are integers from 0 to 15. As shown, n and m are never 0 at the same time. ]

The ester wax preferably used in the present invention preferably has a hardness of 0.5 to 5.0.
The hardness of the ester wax is 20 mmφ in diameter and 5 in thickness.
It is a value obtained by measuring the Vickers hardness using, for example, a dynamic ultra-micro hardness meter (DUH-200) manufactured by Shimadzu Corporation after manufacturing a sample having a cylindrical shape of mm. The measurement conditions are
Vickers hardness is obtained by displacing 10 μm under a condition of a load rate of 9.67 mm / sec with a load of 0.5 g and holding it for 15 seconds, measuring the obtained dent shape. The hardness of the ester wax preferably used in the present invention is 0.5 to 5.0.
Indicates the value of. If the material has a hardness of less than 0.5 and has a low softening point, the pressure dependency and the process speed dependency of the fixing device become large, and the high temperature offset resistance effect is apt to be insufficiently expressed. Since the stability is poor and the release agent itself has a small self-cohesive force, the high temperature offset is likely to be insufficient in the same manner. Specific compounds include the following compounds.

[0053]

Embedded image

In recent years, the need for full-color double-sided images has been increasing, and in forming a double-sided image, the toner image on the transfer paper first formed on the front surface is fixed even when the image is formed next on the rear surface. There is a possibility of passing through the heating part of the container again, and it is necessary to more fully consider the high temperature offset resistance of the toner. Therefore, in the present invention, it is essential to add a large amount of the low softening point substance. Specifically, the low softening point substance is preferably added to the toner in an amount of 5 to 30% by weight. Addition of less than 5% by weight does not show sufficient high-temperature offset resistance, and the image on the back side tends to show an offset phenomenon when fixing a double-sided image. On the other hand, if it exceeds 30% by weight, coalescence of the toner particles is likely to occur during granulation in the production by the polymerization method, and particles having a wide particle size distribution are likely to be produced, which is not suitable for the present invention.

In the present invention, it is preferable to add a charge control agent to the polymer particles for the purpose of controlling the chargeability of the toner.

As these charge control agents, among known ones, those having almost no polymerization inhibitory property and water phase transfer property are used. For example, as positive charge control agents, nigrosine dyes, triphenylmethane dyes, quaternary compounds are used. Examples thereof include ammonium salts, guanidine derivatives, imidazole derivatives, amine compounds, and the like. As negative charge control agents, metal-containing salicylic acid compounds, metal-containing monoazo dye compounds, urea derivatives, styrene-acrylic acid copolymers, styrene- Methacrylic acid copolymers may be mentioned.

The amount of these charge control agents added is preferably 0.1 to 10% by weight of the polymerizable monomer.

As the polymerization initiator used for the polymerization of the polymer particles in the present invention, any suitable polymerization initiator such as 2,2'-azobis- (2,4-divaleronitrile), 2,2 is used. '-Azobisisobutyronitrile, 1,
Azo-based or diazo-based polymerization initiators such as 1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; Examples thereof include peroxide type polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyloxy carbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide.

These polymerization initiators are preferably added in an amount of 0.5 to 20% by weight of the polymerizable monomer, and they may be used alone or in combination.

In the present invention, in order to control the molecular weight of the polymer particles, known crosslinking agents and chain transfer agents may be added, and the preferable addition amount is 0.001 of the polymerizable monomer. ~ 15% by weight.

Any suitable stabilizer is used in the dispersion medium used in the present invention. For example, as an inorganic compound, tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate bentonite , Silica, alumina and the like. As the organic compound, polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid, its salt, polymethacrylic acid, its salt, starch, etc. are dispersed in an aqueous phase. Can be used. It is preferable to use 0.2 to 20 parts by weight of these stabilizers per 100 parts by weight of the polymerizable monomer.

When an inorganic compound is used among these stabilizers, a commercially available product may be used as it is, but in order to obtain fine particles, the inorganic compound may be produced in a dispersion medium.

For example, in the case of tricalcium phosphate, it is advisable to mix the sodium phosphate aqueous solution and the calcium chloride aqueous solution under high stirring.

In order to finely disperse these stabilizers, 0.001 to 100 parts by weight of the polymerizable monomer is added.
You may use 0.1 weight part surfactant. this is,
It is for promoting the initial action of the dispersion stabilizer, and specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, and octyl acid. Sodium, sodium laurate, sodium stearate,
And calcium oleate.

On the other hand, the coating step used in the present invention is a known coating method such as a seed polymerization method;
Known methods such as a method of adding a resin emulsion to polymer particles and adhering and mixing the resin emulsion as described in Japanese Patent No. 45558 can be used, such as a resin precipitation method used in so-called capsule toner.

Examples of the polymerizable monomer used in the coating step of the present invention include styrenes such as styrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, p-methoxystyrene and p-ethylstyrene. Monomers, acrylic acid, methacrylic acid, and methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate , Acrylates such as stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate. , Dodecyl methacrylate, methacrylic acid 2-ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid esters such as diethylaminoethyl methacrylate and other acrylonitrile, methacrylonitrile, and the like monomers acrylamide.

These monomers may be used alone or in combination. Among the above monomers, using styrene or a styrene derivative alone or in admixture with other monomers enhances the adsorptivity to the polymer particles, and enhances the blocking resistance and durability. preferable.

Further, a crosslinking agent may be added to the monomer used in the coating step of the present invention to further impart blocking resistance and the like.

As the crosslinking agent used in the present invention, any known crosslinking agent can be used. The crosslinking agent preferably used is a compound having two or more polymerizable double bonds, such as divinylbenzene,
Aromatic divinyl compounds such as divinylnaphthalene and their derivatives such as ethylene glycol dimethacrylate, diethylene glycol methacrylate, triethylene glycol methacrylate, trimethylolpropane triacrylate, allyl methacrylate, t-
All divinyl such as diethylenic carboxylic acid ester, N, N-divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone, such as butylaminoethyl methacrylate, tetraethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, etc. A compound, a compound having three or more vinyl groups, and the like are used alone or as a mixture.

Furthermore, ethylene glycol, triethylene glycol, 1,2-propylene glycol,
1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A , Polyoxypropyleneized bisphenol A and other dihydric alcohols; maleic acid, fumaric acid, mesaconinic acid, citraconic acid,
Itaconic acid, glutaconic acid, phthalic acid, isophthalic acid,
Dibasic acids and their derivatives such as terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, their anhydrides or their esters with lower alcohols; glycerin, trimethylolpropane, pentaerythritol, etc. Trivalent or higher alcohols; and trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid are used in the present invention as a crosslinking agent.

The amount of such a crosslinking agent added to the monomer is 0.005 to 20 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the monomer. If the amount added is too large, the toner becomes unmelted and the fixability of the toner is impaired. On the other hand, if the amount is too small, it becomes difficult to impart the characteristics of the toner such as durability and storability.

As the polymerization initiator in the coating step of the present invention, a polyfunctional organic peroxide polymerization initiator having two or more peroxide bonds in the molecule is used.

That is, in the present invention, since the above-mentioned initiator has a function of stabilizing the formed coating layer at the initial stage of polymerization, and it becomes possible to make the polymer chain three-dimensional after the polymerization.
It has the function of simultaneously amplifying the strength of the surface of the coated particles and the homogeneity of their surface properties even under a thin film. Therefore, even if the addition amount in the coating step is small, coating stability higher than that of the conventional polymerization initiator can be obtained.

Examples of the polyfunctional organic peroxide polymerization initiator used in the present invention include dialkyl peroxides, peroxycarbonates, alkyl peroxides, and ketal peroxides, such as 2,5- Dimethyl
2,5-bis (t-butylperoxy) hexane, di-
t-butyl peroxyhexahydroterephthalate,
1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (4,4-t-butylperoxycyclohexyl) propane, 1,6-bis (t-butylperoxycarbonyloxy) hexane, diethylene glycol -Bis (t-butyl peroxycarbonate) and the like.

The above polyfunctional organic peroxide polymerization initiator is
It is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer. When the amount of the polymerization initiator added exceeds 10 parts by weight,
Not only the amount used, but also self-emulsification increases. Further, if it is less than 0.1 part by weight, a sufficient degree of polymerization cannot be obtained.

The above-mentioned polymerization initiator of the present invention can be used in combination with a known polymerization initiator.

For example, as the oil-soluble polymerization initiator,
2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,
Azo- or diazo-type polymerization initiators such as 1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl Examples thereof include peroxide-based polymerization initiators such as peroxide, methyl ethyl ketone peroxide, diisopropyl peroxy carbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide.

Any known water-soluble polymerization initiator can be used, and examples thereof include persulfates such as potassium persulfate, ammonium persulfate and sodium persulfate, and hydrogen peroxide. .

In the coating step of the present invention, 0.001 to 0.1% by weight of a surfactant is used with respect to the polymerizable monomer in order to stabilize the emulsion of the dropped polymerizable monomer system. Good. This is to promote the emulsification and dispersion of the above polymerizable monomer system, and specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate,
Examples include sodium pentadecyl sulfate, sodium stearate, calcium oleate and the like.

The toner used in the present invention can be obtained by the following method.

That is, a releasing agent, a coloring agent,
A monomer system in which a charge control agent, a polymerization initiator, and other additives were added and uniformly dissolved or dispersed by a homogenizer, an ultrasonic disperser, or the like was added to an ordinary stirrer or a homogenizer in an aqueous phase containing a dispersion stabilizer. Disperse with a mixer, homogenizer, etc.

Preferably, the stirring speed is such that the monomer droplets have the desired particle size, generally less than 30 μm.
Adjust the time and granulate.

After that, stirring may be performed to the extent that the particle state is maintained and the particles are prevented from settling by the action of the dispersion stabilizer.

The polymerization temperature is 40 ° C. or higher, generally 50 to 9
The polymerization is carried out at a temperature of 0 ° C.

The temperature may be raised in the latter half of the polymerization reaction.

Then, the pH of the above suspension system is adjusted to alkali, and a polymerizable monomer system in which a polymerization initiator for coating the polymer particles is previously dissolved is carefully added dropwise with vigorous stirring.

Further, a water-soluble polymerization initiator, a surfactant or the like may be added to this to emulsify the polymerizable monomer, and the suspension particles (polymer particles) may be adsorbed and coated.

Then, the temperature is raised to 50 to 90 ° C. and heating is performed to polymerize the coating layer of the suspension particles (polymer particles) for 2 to 10 hours.

Further, the temperature may be raised in the latter half of the polymerization reaction, and in order to remove unreacted polymerizable monomers, by-products, etc. which may cause odor during fixing of the toner, the latter half of the reaction or the polymerization. After completion of the reaction, the aqueous medium may be partially distilled off.

After completion of the reaction, the produced synthetic resin particles (toner particles) are collected by washing, filtration and dried.

In the suspension polymerization method, it is usually preferred to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the polymerizable monomer system.

[0092]

The present invention will be described below with reference to examples.
They do not limit the invention in any way. The production examples of the toners used in the examples of the present invention and the comparative examples are listed below. “Parts” means “parts by weight”.

(Production Example 1) To 710 g of ion-exchanged water, 0.
It was charged 1M-Na ₃ PO ₄ aqueous solution 450 g, followed by heating to 60 ° C., using a TK homomixer (manufactured by Tokushu Kika) and stirred at 12,000 rpm.

68 g of 1.0 M CaCl ₂ aqueous solution
Was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

On the other hand, styrene monomer 165 parts n-butyl acrylate 35 parts Copper phthalocyanine pigment 14 parts Styrene-methacrylic acid-methyl methacrylate 9 parts (monomer weight ratio = 85: 5: 10) Paraffin wax (mp 60 ° C.) 60 parts -T-Butyl salicylate metal compound 1 part

The above formulation was heated to 60 ° C., and 12,000 rpm was obtained using a TK type homomixer (made by Tokushu Kika Co., Ltd.).
Was uniformly dissolved and dispersed.

10 parts of a polymerization initiator 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved in this,
A polymerizable monomer composition was prepared.

The above polymerizable monomer composition was put into the above aqueous medium and stirred at 60 ° C. under N ₂ atmosphere with a TK type homomixer at 10,000 rpm for 20 minutes to granulate. Then, while stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and the reaction was carried out for 10 hours to obtain polymer particles.

The volume average particle diameter (D ₄ ) of the polymer particles obtained from a Coulter counter was 6.21 μm. Coulter counter model TA-II for measurement
(Manufactured by Coulter Electronics) was used.

After the completion of the polymerization reaction, the suspension system was cooled, and 3.6 parts of Na ₂ CO ₃ was added and dissolved therein.

Next, a polymerizable monomer system consisting of styrene monomer 90 parts n-butyl acrylate 10 parts 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane 5 parts was metered (manufactured by Nippon Feeder). 4.0 with a dropping rate of 0.5 ml / min.
ml was dropped, and the surface of the polymer particles was adsorbed and coated.

After the completion of dropping, the temperature was raised to 80 ° C. with stirring and polymerization was carried out for 6 hours. The volume average diameter of the polymer particles after coating, determined by a Coulter counter, was 6.70 μm.

Next, this was cooled to room temperature, hydrochloric acid was added to dissolve calcium phosphate, and then the toner was obtained through the steps of filtration, washing with water and drying.

1.2 parts of hydrophobic titanium oxide fine powder was externally added to 100 parts of the obtained toner to obtain toner A having titanium oxide fine powder on the toner surface.

To 6 parts of this externally added toner, 94 parts of a ferrite carrier coated with an acrylic resin was mixed to prepare a two-component developer.

Production Example 2 The composition of the polymerizable monomer composition of Production Example 1 was as follows: styrene monomer 165 parts n-butyl acrylate 35 parts copper phthalocyanine pigment 14 parts saturated polyester 10 parts (terephthalic acid-propylene oxide modified bisphenol A: Acid value 15, peak molecular weight 6000) Compound (2) (mp 59 ° C.) 60 parts Di-t-butylsalicylic acid metal compound 1.5 parts In the same manner as in Production Example 1 except that 1.5 parts were used, and the volume average diameter was 6.
Polymer particles of 01 μm were obtained.

After the completion of the polymerization reaction, the suspension system was cooled, and 3.6 parts of Na ₂ O ₃ was added and dissolved therein.

Then, a coating treatment was conducted in the same manner as in Production Example 1 except that a polymerizable monomer system consisting of styrene monomer 90 parts n-butyl acrylate 10 parts di-t-butyl-oxyhexahydrophthalate 0.5 part was used. The coating resin particles having a volume average diameter of 6.49 μm were obtained.

Next, this was cooled to room temperature, hydrochloric acid was added to dissolve the calcium phosphate, and after the steps of filtration, washing with water and drying, a toner was obtained.

1.2 parts of hydrophobic titanium oxide fine powder was externally added to 100 parts of the obtained toner to obtain toner B having titanium oxide fine powder on the toner surface.

To 6 parts of this externally added toner, 94 parts of a ferrite carrier coated with an acrylic resin was mixed to prepare a two-component developer.

(Production Example 3) The composition of the polymerizable monomer composition of Production Example 1 was as follows: styrene monomer 165 parts n-butyl acrylate 35 parts copper phthalocyanine pigment 14 parts saturated polyester 10 parts (terephthalic acid-propylene oxide modified bisphenol A: Acid value 15, peak molecular weight 6000) Compound (3) (mp 59 ° C.) 60 parts Di-t-butylsalicylic acid metal compound 1 part The same as in Production Example 1 except that the volume average diameter was 6.
Polymer particles of 64 μm were obtained.

After the completion of the polymerization reaction, the suspension system was cooled, and 3.6 parts of Na ₂ O ₃ was added and dissolved therein.

Then, a polymerizable monomer system consisting of 90 parts of styrene monomer, 10 parts of n-butyl acrylate, 10 parts of divinylbenzene, 10 parts of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane was used. In the same manner as in Production Example 1, polymer particles having a volume average diameter of 6.91 μm were obtained.

Then, the polymer particles were coated in the same manner as in Production Example 1 to obtain coated resin particles having a volume average diameter of 6.47 μm.

Next, this was cooled to room temperature, hydrochloric acid was added to dissolve the calcium phosphate, and the toner was obtained through the steps of filtration, washing with water and drying.

1.2 parts of hydrophobic titanium oxide fine powder was externally added to 100 parts of the obtained toner to obtain toner C having the titanium oxide fine powder on the toner surface.

To 6 parts of this externally added toner, 94 parts of a ferrite carrier coated with an acrylic resin was mixed to obtain a two-component developer.

(Production Example 4) In the same manner as in Production Example 1, polymer particles having a volume average diameter of 7.70 μm were obtained.

After the completion of the polymerization reaction, the suspension system was cooled, and 3.6 parts of Na ₂ O ₃ was added and dissolved therein.

Then, 90 parts of styrene monomer, 10 parts of acrylic acid, 10 parts of n-butyl acrylate and 0.1 part of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane were metered by a metering pump (Nippon Feeder). 0.05m using
2.9 ml was dropped at a dropping rate of 1 / min to adsorb and coat the polymer particles.

After completion of the dropping, 1.48 g of potassium persulfate was gradually added to this with stirring, and the mixture was stirred and dissolved.
Then, the temperature was raised to 70 ° C., and the above synthetic resin monomer was polymerized for 6 hours.

The volume average diameter at this time was 7.99 μm.

Next, this was cooled to room temperature, hydrochloric acid was added to dissolve calcium phosphate, and then the toner was obtained through the steps of filtration, washing with water and drying.

To 100 parts of the obtained toner, 1.2 parts of hydrophobic titanium oxide fine powder was externally added to obtain a toner D having the titanium oxide fine powder on the toner surface.

To 6 parts of this externally added toner, 94 parts of a ferrite carrier coated with an acrylic resin was mixed to obtain a two-component developer.

Production Example 5 The composition of the polymerizable monomer composition of Production Example 1 was styrene monomer 165 parts n-butyl acrylate 35 parts Hydrophobized magnetic material 140 parts Di-t-butyl salicylate metal compound 1 part Styrene- Methacrylic acid copolymer 10 parts Paraffin wax (mp 60 ° C.) 20 parts Di-t-butylsalicylic acid metal compound 1 part The same as Production Example 1 except that the volume average diameter is 6.9.
Polymer particles of 0 μm were obtained.

After the completion of the polymerization reaction, the suspension system was cooled, and 3.6 parts of Na ₂ O ₃ was added and dissolved therein.

Next, 90 parts of styrene monomer, 10 parts of n-butyl acrylate, 5 parts of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, and 0.05 m were measured using a metering pump (manufactured by Nippon Feeder).
2.2 ml was dropped at a dropping rate of 1 / min to adsorb and coat the polymer particles.

After the completion of dropping, the temperature was raised to 70 ° C. with stirring, and the above synthetic resin monomer was polymerized for 6 hours.

The volume average diameter at this time was 7.11 μm.

Next, this was cooled to room temperature, hydrochloric acid was added to dissolve the calcium phosphate, and the toner was obtained through the steps of filtration, washing with water and drying.

To 100 parts of the obtained toner, 1.2 parts of hydrophobic titanium oxide fine powder was externally added to obtain a toner E having the titanium oxide fine powder on the toner surface.

To 6 parts of this externally added toner, 94 parts of a ferrite carrier coated with an acrylic resin was mixed to obtain a two-component developer.

Production Example 6 A volume average diameter of 6.47 μm was obtained in the same manner as in Production Example 1 except that the paraffin wax was replaced with the compound (1) in the formulation of the polymerizable monomer composition of Production Example 1.
Polymer particles of m were obtained.

After the completion of the polymerization reaction, the suspension system was cooled, and 3.6 parts of Na ₂ O ₃ was added and dissolved therein.

Then, 80 parts of styrene monomer and 20 parts of n-butyl acrylate were added to 0.05 m using a metering pump (manufactured by Nippon Feeder).
2.2 ml was dropped at a dropping rate of 1 / min to adsorb and coat the polymer particles.

After completion of dropping, the temperature was raised to 70 ° C. with stirring to polymerize the above synthetic resin monomer for 6 hours.

The volume average at this time was 7.11 μm.

Further, 1.12 g of potassium persulfate was gradually added to this, and stirred and dissolved. After the dropping was completed, the temperature was raised to 80 ° C. with stirring, and the above synthetic resin monomer was polymerized for 6 hours.

The volume average diameter of the polymer particles after coating is
It was 6.58 μm.

Next, this was cooled to room temperature, hydrochloric acid was added to dissolve calcium phosphate, and then toners were obtained through the steps of filtration, washing with water and drying.

1.2 parts of hydrophobic titanium oxide fine powder was externally added to 100 parts of the obtained toner to obtain toner F having titanium oxide fine powder on the toner surface.

To 6 parts of this externally added toner, 94 parts of a ferrite carrier coated with an acrylic resin was mixed to prepare a two-component developer.

(Production Example 7) Polymer particles were obtained in the same manner as in Production Example 1.

After completion of the reaction, the mixture was cooled, hydrochloric acid was added to dissolve the calcium phosphate, and the mixture was filtered, washed with water and dried,
A toner having a weight average diameter of 8.1 μm was obtained.

1.2 parts of hydrophobic titanium oxide fine powder was externally added to 100 parts of the obtained toner to obtain toner G having titanium oxide fine powder on the toner surface.

To 6 parts of this externally added toner, 94 parts of a ferrite carrier coated with an acrylic resin was mixed to prepare a two-component developer.

Examples using the above toner will be shown below.

[0150] Example 1 using the developer prepared using toner A produced in accordance with Production Example 1, a commercially available full-color copying machine CLC5
An image was copied using a No. 00 remodeling machine (manufactured by Canon) at 23 ° C. and 60% RH, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

Even at the durability of 100,000 sheets, no image defects such as decrease in image density, toner scattering and fog were observed, and good image quality durability was exhibited.

Further, the tribo value of the charging property was measured. As a result, the initial value was -26 mC / kg, and the endurance value was -27 mC / k.
It showed a uniform and stable value as g.

Example 2 The toner A prepared according to the above Production Example 1 was used, and the developer prepared was used.
An image was copied in an environment of 80 ° C. and 80% RH, and the image durability, toner scattering, fog and the like were evaluated, and the results are shown in Table 1.

Even at the durability of 100,000 sheets, no image defects such as a decrease in image density, toner scattering, and fog were observed, and good image quality durability was exhibited.

Further, the tribo value of the charging property was measured, and it was found to be -24 mC / kg at the initial stage and -24 mC / k after the endurance test.
It showed a uniform and stable value as g.

Example 3 A developer prepared by using the toner B prepared according to the above Production Example 2 was used in a modified CLC500 machine at 23 ° C.
An image was copied under a 60% RH environment, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

Even at the durability of 100,000 sheets, no image defects such as decrease in image density, toner scattering, and fog were observed, and good image quality durability was exhibited.

The tribo value of the charging property was measured. As a result, the initial value was -27 mC / kg, and the value after endurance was -27 mC / k.
It showed a uniform and stable value as g.

Example 4 A developer prepared by using the toner C prepared according to the above Production Example 3 was used, and it was heated at 23 ° C. in a modified CLC500 machine.
An image was copied under a 60% RH environment, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

Even at the durability of 100,000 sheets, no image defects such as decrease in image density, toner scattering and fog were observed, and good image quality durability was exhibited.

The tribo value of the charging property was measured. As a result, the initial value was -28 mC / kg, and the value after endurance was -29 mC / k.
It showed a uniform and stable value as g.

Example 5 Using a developer prepared using Toner C prepared according to Production Example 3 above, at 28 ° C. in a modified CLC500 machine.
Images were copied under an environment of 80% RH, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

Even at the durability of 100,000 sheets, no image defects such as decrease in image density, toner scattering and fog were observed, and good image quality durability was exhibited.

Further, the tribo value for the charging property was measured, and it was found to be -25 mC / kg at the initial stage and -25 mC / k after the endurance.
It showed a uniform and stable value as g.

Example 6 Using a developer prepared using Toner D prepared according to Production Example 4 above, at 28 ° C. in a modified CLC500 machine.
Images were copied under an environment of 80% RH, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

Even at the durability of 100,000 sheets, no image defects such as decrease in image density, toner scattering and fog were observed, and good image quality durability was exhibited.

The tribo value of the charging property was measured. As a result, the initial value was -27 mC / kg, and the value after endurance was -26 mC / k.
It showed a uniform and stable value as g.

Example 7 Using a developer prepared by using Toner E prepared according to the above Production Example 5, a CLC500 remodeling machine was used at 23 ° C.
An image was copied under a 60% RH environment, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

Even at the durability of 100,000 sheets, no image defects such as decrease in image density, toner scattering and fog were observed, and good image quality durability was exhibited.

Further, the tribo value of the charging property was measured, and it was found to be −25 mC / kg at the initial stage and −23 mC / k after the endurance.
It showed a uniform and stable value as g.

Example 8 Using a developer prepared by using Toner E prepared according to the above Production Example 5, a CLC500 remodeling machine was used at 28 ° C.
Images were copied under an environment of 80% RH, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

Even at the durability of 100,000 sheets, no image defects such as decrease in image density, toner scattering and fog were observed, and good image quality durability was exhibited.

Further, the tribo value of the charging property was measured. As a result, the initial value was -22 mC / kg and the value after endurance was -22 mC / k.
It showed a uniform and stable value as g.

Comparative Example 1 Using a developer prepared using Toner F produced according to Production Example 6 above, using a modified CLC500 machine at 28 ° C.
Images were copied under an environment of 80% RH, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

At the endurance of 10,000 sheets, image defects such as a decrease in image density, toner scattering, and fog were observed.

For the purpose of evaluating the chargeability of the toner,
When the tribo value was measured, there was a decreasing tendency at the initial value of -27 mC / kg and after the endurance of -21 mC / kg.

Comparative Example 2 Using a developer prepared by using Toner G prepared according to the above Production Example 7, a CLC500 remodeling machine was used at 28 ° C.
Images were copied under an environment of 80% RH, and the image durability, toner scattering, fog, etc. were evaluated, and the results are shown in Table 1.

At the endurance of 30,000 sheets, image defects such as a decrease in image density, toner scattering, and fog were recognized.

For the purpose of evaluating the chargeability of the toner,
When the tribo value was measured, there was a decreasing tendency at the initial stage of -27 mC / kg and after the endurance of -20 mC / kg.

[0180]

[Table 1]

[0181]

According to the present invention, a polyfunctional organic peroxide polymerization initiator is used for forming a toner coating layer, whereby a uniform coating layer is formed with a minimum amount of coating and productivity is improved. In addition to improving the image quality durability, it is possible to simultaneously achieve the charging property, the uniform charging, and the stability thereof.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takehiko Chiba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Koji Inaba 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non non corporation

Claims (4)

[Claims] 1. A toner for developing an electrostatic charge image having a coating layer on polymer particles, wherein the coating layer uses a polyfunctional organic peroxide polymerization initiator having two or more peroxide bonds in the molecule. A toner for developing an electrostatic charge image, which is formed by the following method. 2. The toner according to claim 1, wherein the low softening point substance is encapsulated in the coating layer and directly polymerized by observing the cross-sectional layer of the toner using a transmission electron microscope (TEM). Toner for charge image development. 3. The toner for developing an electrostatic charge image according to claim 2, wherein the low softening point substance is an ester wax having at least one long chain ester portion having 10 or more carbon atoms. 4. An electrostatic charge image developing method, characterized in that a coating layer is formed on a polymer particle using a polyfunctional organic peroxide polymerization initiator having two or more peroxide bonds in the molecule. Toner manufacturing method.