JPH0664358B2 - toner - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a toner used for converting a latent image formed in a recording method such as an electrophotographic method into a visible image, and a manufacturing method thereof.

BACKGROUND OF THE INVENTION As a fixing method of a toner image in a recording method such as an electrophotographic method, there are known three kinds of methods: heat fixing, solvent fixing and pressure fixing. Due to environmental problems and the like, a heat fixing method and a pressure fixing method which do not use a solvent are often used these days.

A toner composed of a coloring material and a binder has been conventionally used in the heat fixing method, and a normal toner is also used in pressure fixing. In recent years, a capsule toner in which the toner is contained in a microcapsule is used. The use of is being considered.

The capsule toner is a microcapsule form obtained by forming a resin outer shell having a property of being destroyed by application of pressure around a core substance containing a coloring material such as carbon black and a binder such as a polymer and an oily solvent. Toner. A normal toner is a toner containing a coloring material such as carbon black in a state of being dispersed in a binder component.

[Prior Art and Problems] Conventionally known capsule toners and ordinary toners are not always satisfactory in various characteristics originally required as toners.

For example, a toner having an insulating surface has been generally used as a developer for electrophotography, but recently, a toner having an appropriate positive or negative triboelectric charging property on the toner surface has been developed. There is.

That is, a toner used in electrophotography of a system in which toner is charged by rubbing with carrier particles such as iron powder or toner such as fur, and the charged toner is attracted to a latent image has excellent triboelectric chargeability. Is desirable.

The triboelectrification property on the toner surface is conventionally obtained by a method in which a powdery toner and a charge control agent such as silica fine powder are contact mixed with each other in a powder state, or a charge control agent is added to a toner dispersion liquid. The toner is attached to the surface of the toner by using a method such as a drying method.

However, according to the study by the present inventor, it has been found that the toner to which the charge control agent is applied by the above conventional method has a problem that the charge control agent attached to the toner surface is easily desorbed during the toner storage. . Toner from which such a large amount of charge control agent has been desorbed is likely to have insufficient developing characteristics, which adversely affects image characteristics such as sharpness and density of the obtained visible image.

[Object of the Invention] The main object of the present invention is to provide a toner having improved triboelectricity and stability of triboelectricity.

SUMMARY OF THE INVENTION According to the present invention, at least one kind of charge control agent (fine powder) selected from the group consisting of silica fine powder, alumina fine powder and titanium dioxide fine powder is bound to the surface by a silane coupling agent. It is in the resulting toner.

[Advantages of the Invention] The toner of the present invention has a charge control agent layer in which a charge control agent is bound to each other by using a reaction product of a silane coupling agent as a binding agent, and thus exhibits good triboelectric chargeability. , Shows excellent properties as a developer used for carrying out recording methods such as electrophotography. Further, the excellent triboelectric chargeability of the toner of the present invention hardly deteriorates even after long-term storage or physical impact.

Therefore, the toner of the present invention is particularly advantageous as a toner used in electrophotography, which utilizes triboelectric charging properties.

DETAILED DESCRIPTION OF THE INVENTION The toner of the present invention is different from the conventional toner in which the charge control agent is simply attached to the surface thereof. The charge control agent is bonded to each other by the reaction product of the silane coupling agent, and Has a charge control agent layer in which both the charge control agent and the surface of the toner particles are firmly bound by the reaction product.

The toner of the present invention exhibits good triboelectric chargeability regardless of whether it is a capsule toner or a normal toner.

First, the capsule toner will be described.

In producing the capsule toner, the microcapsules can be produced according to a usual method using the raw materials usually used for producing the microcapsules.

That is, a method for producing a capsule toner by forming a resin outer shell having a property of being destroyed by application of pressure around a core material containing a coloring material such as carbon black and a binder such as a polymer and an oily solvent is already known. Are known.

In the production of the encapsulated toner of the present invention, the outer shell of the core substance is formed by utilizing a microcapsule production method such as an interfacial polymerization method or an external polymerization method, particularly a microcapsule production method based on a polymerization reaction in an aqueous liquid. After that,
A known method such as a method of washing with water can be used.

Examples of the polymer that can be used as the component of the binder in the encapsulated toner of the present invention include the following compounds.

Polyolefin, olefin copolymer, styrene resin, styrene-butadiene copolymer, epoxy resin,
Polyester, rubber, polyvinylpyrrolidone, polyamide, coumarone / indene copolymer, methyl vinyl ether / maleic anhydride copolymer, amino resin, polyurethane, polyurea, homopolymer or copolymer of acrylic ester, homopolymer of methacrylic ester or Copolymers, copolymers of acrylic acid and long-chain alkyl methacrylates, polyvinyl acetate, polyvinyl chloride.

Particularly preferable as the above-mentioned binder polymer is a homopolymer or copolymer of acrylic acid ester, a homopolymer or copolymer of methacrylic acid ester, or a styrene-butadiene copolymer.

Examples of the oily solvent that can be used as the component of the binder include a high boiling point solvent having a boiling point of 150 ° C. or higher (hereinafter, also simply referred to as a high boiling point solvent) capable of dissolving or swelling the above polymer. An example of this high boiling point solvent is described below.

Phthalates (eg, diethyl phthalate, dibutyl phthalate); Aliphatic dicarboxylic esters (eg,
Diethyl malonate, diethyl oxalate); phosphoric acid esters (eg, tricresyl phosphate, trixylyl phosphate); citric acid esters (eg, o-acetyltriethyl citrate, tributyl citrate); benzoic acid esters (Eg, butyl benzoate, hexyl benzoate); Aliphatic acid esters (eg, hexadecyl myristate, dioctyl adipate); Alkyl naphthalenes (eg, methyl naphthalene, dimethyl naphthalene, monoisopropyl naphthalene, diisopropyl naphthalene); Alkyl diphenyl ethers (Eg, o-,
m-, p-methyldiphenyl ether); amide compounds of higher fatty acid or aromatic sulfonic acid (eg, N, N-dimethyllauroamide, N-butylbenzenesulfonamide); trimellitic acid esters (eg, trioctyltri) Melitate); Diarylalkanes (eg, diarylmethane such as dimethylphenylphenylmethane, 1-
Phenyl-1-methylphenylethane, 1-dimethylphenyl-1-phenylethane, 1-ethylphenyl-1
-Diarylethanes such as phenylethane).

In the present invention, the binder is preferably a composition containing both a polymer and a high boiling point solvent.

Black toners such as carbon black and grafted carbon black are generally used as coloring materials for electrophotographic toners, but various chromatic colorants such as blue, red and yellow are also used. ing. These coloring materials can also be used in the capsule toner.

The core substance of the encapsulated toner may contain magnetic particles. As the magnetic particles, known magnetic particles for magnetic toner (magnetizable particles) can be used. Examples of such magnetic particles include cobalt, iron,
Alternatively, magnetic particles made of a simple metal such as nickel, an alloy, or a metal compound can be used. In addition,
When colored magnetic particles such as black magnetite are used as the magnetic particles, the colored magnetic particles such as magnetite can also be used as a component that serves both as the magnetic particles and the coloring material.

The type of resin forming the outer shell of the capsule toner is not particularly limited, but in consideration of the properties as the capsule toner, the outer shell resin is preferably polyurea, polyurethane, polyamide, polyester or epoxy resin. These resins can be used alone or as a mixture as a resin for forming an outer shell. The capsule toner of the present invention is composed of a polyurea resin, a polyurethane resin, and a composite wall containing at least one of polyamide resins, the strength of the outer shell,
It is particularly preferable in consideration of flexibility and the like. It is also preferable to use a viscosity preventive agent such as silicone oil in combination.

Next, a method for producing a capsule toner will be described by taking as an example a method for producing a capsule toner comprising an outer shell of a polyurethane resin or a polyurea resin.

By forming an outer shell made of a polyurea resin and / or a polyurethane resin around an oil-drop dispersed core substance containing a coloring material and a binder (and optionally magnetic particles) in an aqueous liquid, a micro shell is formed. Methods for producing capsules are already known, and these known methods can also be used for producing the encapsulated toner of the present invention.

For example, as a method for producing microcapsules utilizing a polymerization reaction that can be used for producing a capsule toner, an interfacial polymerization method can be mentioned. Further, as another example of the method for producing a microcapsule utilizing a polymerization reaction that can be used in the present invention, an internal polymerization method and an external polymerization method can be mentioned.

The outer shell made of polyurea resin and / or polyurethane resin includes polyisocyanate such as diisocyanate, triisocyanate, tetraisocyanate, polyisocyanate prepolymer, diamine, triamine,
It can be easily formed as an outer shell of a microcapsule by reacting a polyamine such as tetraamine, a prepolymer containing two or more amino groups, piperazine and its derivative, and a polyol with an interfacial polymerization method in an aqueous solvent. It has been known.

Further, a composite wall composed of a polyurea resin and / or polyurethane and a polyamide resin which are preferable as the outer shell of the capsule toner, for example, a composite wall composed of a polyurea resin and a polyamide resin, a composite wall composed of a polyurethane resin and a polyamide resin, or a polyurea resin, A composite wall made of a polyurethane resin and a polyamide resin can be manufactured by the following method.

The composite wall made of polyurea resin and polyamide resin, the composite wall made of polyurethane resin and polyamide resin, for example, using polyisocyanate and acid chloride and polyami and polyol, pH adjustment of the emulsifying medium to be the reaction liquid, and then heating. It can be prepared by an interfacial polymerization method consisting of performing. Further, the composite wall composed of polyurea resin and polyamide resin can be prepared by using polyisocyanate, acid chloride and polyamine to adjust the pH of the emulsifying medium to be the reaction solution and then heating. For details of the method for producing the composite wall composed of the polyurea resin and the polyamide resin, and the composite wall composed of the polyurethane resin and the polyamide resin, see JP-A-58.
-66948 gazette. The outer shell composed of such a composite wall is particularly suitable for forming an encapsulated toner containing magnetic particles in a core substance.

The monomers involved in the polymerization reaction for forming the outer shell resin differ depending on the resin forming the outer shell, but usually two or more kinds of monomers are used in combination. Examples of such a combination of monomers include a difunctional compound containing a group selected from the group consisting of an isocyanate group, a thioisocyanate group, a bischloroformate group, an acid chloride group and a sulfonichloride group. And at least one compound selected from the group consisting of water, polyamines, polyhydric alcohols, polyhydric thiols, polyhydric amines and polycarboxylic acids.

The microcapsules with the outer shell formed are then washed with water.

On the other hand, a method for producing a toner composed of an ordinary binder and a coloring material is already known, and a known method can be used for producing the ordinary toner of the present invention.

Examples of the binder include homopolymers of styrene and its substitution products, styrene-based copolymers and commonly used resin components. These can be used alone or as a mixture.

As the coloring material, those which can be used for the above-mentioned capsule toner can be used.

The thus prepared capsule toner or normal toner is dispersed in a dispersion liquid. Then, a charge control agent and a silane coupling agent are added to this dispersion liquid, and the reaction product of the silane coupling agent is made to act as a binder of the charge control agent by reacting the reactive silicon compound at a specific temperature or higher.

Charge control agents that can be used in the present invention are silica fine powder, alumina fine powder and titanium dioxide fine powder.
These can be used alone or in combination.
In addition, it is preferable to use the charge control agent in which the surface of each particle is previously subjected to a hydrophobic treatment.
Examples of such surface-treated fine powders include dimethyldichlorosilane-treated silica, hexamethyldisilazane-treated silica, octyltrimethoxysilane-treated silica,
Silicone oil treated silica, aminosilane treated silica and alumina treated with hydrophobic treatment equivalent to this (eg, hexamethyldisilazane treated aluminum oxide)
And titanium dioxide, which may be used alone or in combination.

And these charge control agents have an average particle size of 1 to 100 m.
It is preferably a fine powder in the range of μ.

Usually, the charge control agent is used within a range of 0.5 to 5 parts by weight with respect to 100 parts by weight of toner (uncoated). Particularly, it is preferable to use it within the range of 1 to 4 parts by weight.

When the amount of the charge control agent used is less than 0.5 part by weight, toner particles to which the charge control agent is not applied may be present on the entire surface of the toner, and the chargeability may not be improved sufficiently. Also, 5
If the amount is more than the amount by weight, the charge control agent layer on the surface of the toner becomes too thick and the fixability may not be sufficiently improved.

The silane coupling agent, which is added to the toner dispersion together with the charge control agent, has a silicon atom having a group or an atom capable of binding to the charge control agent and the toner through a hydrolysis reaction or the like. It is a compound.

The group capable of binding to the charge control agent and the toner means an alkoxyl group having 1 to 5 carbon atoms, and the element capable of binding means a halogen atom such as chlorine or iodine. The silane coupling agent has a group such as an amino group, an inocyanate group, a glycidyl group, a vinyl group, and a hydrocarbon group in which all or part of hydrogen is substituted with a fluorine atom, in addition to the above groups and atoms. May be

Specific examples include higher alkyltriethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ.
-Glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, vinylethoxysilane, silica-modified PVA, γ-chloropropyltrimethoxysilane and a silicon-containing brimer having an isocyanate group, and a fluorine-based silane coupling agent (eg, Examples thereof include alkoxysilanes having an alkyl group in which a part or all of hydrogen is substituted with fluorine, and alkoxysilanes having an alkyl group in which a part or all of hydrogen is substituted with fluorine and a halogen atom.

Such a silane coupling agent is usually used in an amount of 0.1 to 3 parts by weight (particularly preferably 0.5 to 3 parts by weight) per 1 part by weight of the charge control agent.
2 parts by weight). If the amount of the siccan wrapping agent is less than 0.1 part by weight, a portion of the charge control agent which is not sufficiently bound is present, and the charge control agent layer in this portion may be peeled off with use. Further, even if more than 3 parts by weight is used, the triboelectric chargeability cannot be remarkably improved.

Conventionally, it is known that the silica fine particles are subjected to a hydrophobic treatment with a silane coupling agent, but this is to impart the silane coupling agent to a part of the surface of the silica fine particles, and like the present invention. It is not known to use the reaction product of a silane coupling agent as a binder to bond charge control agents to one another.

50 ° C. by heating, for example, an aqueous dispersion of toner particles containing a charge control agent and a silane coupling agent.
The above temperature is set (preferably within the range of 50 to 100 ° C.), and the silane coupling agent is reacted. Then, usually, the reaction is carried out and the dispersion solvent is evaporated and removed, and the toner is dried. The time required for this reaction and drying is usually 10
Minutes to 5 hours.

If the temperature is lower than 50 ° C., the silane coupling agent does not react effectively, so that the toner of the present invention having good triboelectric chargeability cannot be manufactured.

As the dispersion liquid, water or water containing a small amount of an organic solvent is usually used.

Since the dried toner contains secondary particles to some extent, the secondary particles are usually released from the association, and secondary particles contained in a trace amount are eliminated by using a sieve or the like.

The toner thus obtained has 100 parts by weight of an uncoated toner in which 0.1 to 3 parts by weight of a reaction product of a silane coupling agent is bonded to 1 part by weight of a charge control agent as a binder. It is covered with a charge control agent layer, which usually comprises 0.5 to 5 parts by weight of a charge control agent.

The charge control agent layer usually has an average layer thickness of 1 to 100 mμ.

In this way, the charge control agent layer in which the charge control agent is bound by the reaction product of the silane coupling agent is different from the conventional state in which the charge control agent is simply attached to the toner surface, and at least each charge control agent is adjusted. The agent fine particles are bonded to each other by using the reaction product as a binder, and are chemically bonded to each other, and also the particles and the toner surface are bonded in the same manner, which is very robust. It is presumed that almost the entire charge control agent layer is covered with the reaction product, and in the normal use, most of the charge control agent layer does not substantially peel off.

Therefore, in addition to having good triboelectric chargeability at the time of toner preparation, the charge control agent is not peeled off due to contact between toner particles or a device when used, and excellent triboelectric chargeability is obtained for a long period of time. When the toner of the present invention is held and used for developing a latent image in electrophotography, the density is not reduced and fog does not occur even if, for example, 2000 or more sheets are copied.

Next, examples and comparative examples of the present invention will be shown. In Examples and Comparative Examples, “%” means “% by weight” unless otherwise specified.

[Example 1] 8 g of polyisobutyl methacrylate (trade name: Acrybase, MM-2002-2, manufactured by Fujikura Kasei Co., Ltd.) was dissolved in 40 g of an oily solution of 4-isopropyl-phenyl-2-phenylethane, and magnetite was further added. A dispersion (magnetic ink) was prepared by kneading and dispersing 44 g of magnetic particles in an automatic mortar.

Separately, 25 g of ethyl acetate is added with 3 mol of toluylene diisocyanate and 1 mol of hexanetriol (trade name: Desmodur L, manufactured by Bayer) and 10 g of silicone oil (trade name, Silicone KF-96, Shin-Etsu Silicone Co., Ltd.). The above dispersion liquid (magnetic ink) was mixed with a solution in which 4 g of the oily phase was prepared to prepare an oily phase.

Methyl cellulose (methoxy group substitution degree)
200 g of a 4% aqueous solution of 1.8, average molecular weight: 15000) was prepared.

The oily phase mixture was emulsified and dispersed in this aqueous liquid to obtain an oil-in-water emulsion in which the average size of oil droplet particles in the emulsion was about 17 μm.

After the emulsion was slowly stirred for about 15 minutes, 80 g of a 2.5 wt% aqueous solution of diethylenetriamine was gradually added dropwise, and the mixture was stirred in a constant temperature bath at 60 ° C. for 3 hours to decapsulate the ethyl acrylate for encapsulation.

The obtained microcapsule dispersion was allowed to stand naturally to precipitate the microcapsules, the upper aqueous layer was discarded, distilled water was added instead, and the mixture was allowed to stand naturally. This washing operation was repeated 20 times to remove methylcellulose and the like adhering to the surface of the microcapsules.

On the other hand, 10.8 g of hydrophobic silica (trade name: Hydrophobic Silica R-976, manufactured by Nippon Aerosil Co., Ltd.) in which the average particle size of the primary particles as the charge control agent is 7 mμ is used in about 6 minutes using a household mixer. Dispersed in 180 g of water.

20 g of this dispersion and 0.5 g of methyltrimethoxysilane were added to the above-mentioned water-washed capsule dispersion and mixed, and then the mixture was poured into a stainless steel pad and placed in an oven at 80 ° C. for 3 days.
It dried over time.

The particles of the obtained dry toner were disentangled and passed through a 400-mesh sieve to remove secondary agglomerates to obtain a capsule toner in which most of them were primary particles.

Example 2 A capsule toner was manufactured in the same manner as in Example 1 except that γ-chloropropyltrimethoxysilane was used instead of methyltrimethoxysilane.

Example 3 A capsule toner was manufactured in the same manner as in Example 1 except that γ-glycidoxypropyltrimethoxysilane was used instead of methyltrimethoxysilane.

[Comparative Example 1] A capsule toner was manufactured in the same manner as in Example 1 except that methyltrimethoxysilane was not used.

Comparative Example 2 In Example 1, microcapsules obtained by drying the washed capsule dispersion liquid without adding methyltrimethoxysilane and hydrophobic silica and 1.2 g of the hydrophobic silica used in Example 1 were used. Were mixed and stirred to produce a capsule toner.

Evaluation of charge amount The potential (surface potential) of the obtained encapsulated toner on the sleeve at the initial stage of rotation (after 5 minutes) and the potential of the encapsulated toner were measured after rotating and stirring for 5 hours in the developing hopper and on the sleeve. The results are shown in Table 1.

The capsule toners obtained in Examples 1 to 3 are Comparative Example 1
Compared with the capsule toners obtained in 1 and 2, the potential on the sleeve in the initial stage of rotation is higher.

In addition, the capsule toners obtained in Examples 1 to 3 are 5
There is almost no change in electric potential after stirring by rotation for a long time. On the other hand, the potential changes of the capsule toners obtained in Comparative Examples 1 and 2 were very large, and the potential of the capsule toner obtained in Comparative Example 2 became 0 V after about 30 minutes.

Copy Test Using the capsule toner obtained in Example 2 as a developer, a repeated copy test using an electrophotographic copying machine (model: FX-2830, manufactured by Fuji Xerox Co., Ltd.) was performed on 2000 sheets of paper to obtain a toner image. The change in concentration was examined. There was no reduction in the density of the toner image in this 2000-sheet copying.

On the other hand, when the copying test was similarly performed on the capsule toner obtained in Comparative Example 1, a slight decrease in the density was observed after copying about 400 sheets. Similarly, when a copying test was conducted on the encapsulated toner produced in Comparative Example 2, a decrease in density was observed after copying 200 to 300 sheets.

Further, when the inside of the device was observed after the test, the charge control agent was found to have adhered to the wall surface of the device after the test of the capsule toner manufactured in Comparative Example 2.

Example 4 A toner comprising 100 parts by weight of styrene-butyl methacrylate, 60 parts by weight of magnetite and 3 parts by weight of nigrosine was prepared according to a conventional method.

60 g of the obtained toner was dispersed in water, and 20 g of the dispersion liquid of the hydrophobic silica and methyltrimethoxysilane used in Example 1 was added thereto and mixed, and then the mixture was poured into a stainless steel pad and the mixture was heated at 60 ° C. Dry in oven for 3 hours.

A copy test was conducted using the obtained toner.
There was no decrease in the density of the toner image in the 00 copy.

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Claims (3)

[Claims] 1. A toner in which at least one kind of charge control agent selected from the group consisting of silica fine powder, alumina fine powder and titanium dioxide fine powder is bonded to the surface by a silane coupling agent. 2. A charge control agent is bound to the toner surface in a ratio of 0.5 to 5 parts by weight to 100 parts by weight of toner particles, and a silane coupling agent is added to 1 part by weight of the charge control agent.
The toner according to claim 1, wherein the toner is bound to the toner surface in a ratio of 0.1 to 3 parts by weight. 3. The charge control agent fine powder having an average particle size of 1 to 100.
The toner according to claim 1, which is in the range of μm.