JPS62212664A - Toner for development - Google Patents

Abstract

PURPOSE:To obtain a toner for development having a good powder characteristic and particularly good fluidity by sticking or incorporating porous silica subjected to a hydrophobic treatment to the surface of toner particles. CONSTITUTION:The toner is capsule toner and is formed by sticking or incorporating porous silica subjected to the hydrophobic treatment to the surface of the shell. The porous silica is formed by double decomposition of sodium silicate and the average grain size thereof is adjusted to <=60mmu. The hydrophobic treatment of the porous silica is executed by a silane coupling agent or titanate coupling agent. The silica treated by a dimethyl dichlorosilane and the silica treated by an isopropyl triisostearoyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate or isopropyl tri(N-aminoethyl-aminoethyl) titanate are more preferable. The content of the silica subjected to the hydrophobic treatment is made 0.05-10wt% per the weight of the capsule toner to or in which the silica subjected to the hydrophobic treatment is not stuck or incorporated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a developing toner used for converting a latent image formed in a recording method such as electrophotography or magnetography into a visible image.

[Background of the Invention] Three types of methods are known for fixing toner images in recording methods such as electrophotography: heat fixing, solvent fixing, and pressure fixing. and.

Due to environmental concerns, heat fixing methods and pressure fixing methods that do not use solvents are often used these days.

Toners consisting of a coloring material and a binder have conventionally been used in the heat fixing method. In the pressure fixing method, normal toner is also used, but in recent years, the use of capsule toner in which toner is contained in microcapsules has been studied.

Capsule toner is a microcapsule type obtained by forming a resin shell that can be destroyed by applying pressure around a core material containing a coloring material such as carbon black and a binder such as a polymer or oil-based solvent. A conventional toner is a toner that contains a coloring material, such as carbon black, dispersed in a calculative component.

[Prior Art and its Problems 1 Conventionally known capsule toners and ordinary toners cannot necessarily be said to be satisfactory in terms of various properties originally required as toners.

For example, toner used as a developer for electrophotography is required to have good powder characteristics, excellent developing performance, and not to stain the surface of the photoreceptor, which is the surface on which the latent image is formed. In the case of a component development method, it is necessary that the surface of the carrier particles used is not contaminated. In addition, the toner used for pressure fixing has good pressure fixing properties, and the off-cert phenomenon (a phenomenon in which toner adheres to the pressure roller surface and stains the roller) occurs on the pressure roller used for pressure fixing. It requires things that are difficult to do.

Therefore, the toner used for pressure fixing properties is determined by powder properties, fixability to support media such as paper (including shelf life of fixed images), non-offset properties, and chargeability depending on the developing method used. and/or conductivity, etc.; however, hitherto known toners were not necessarily satisfactory with respect to the above-mentioned AI properties.

For example, in recent years, with the miniaturization of copying machines as a whole, heat tends to accumulate inside the copying machine, and as a result, the capsule toner stored in the developing device tends to be exposed to high temperature environmental conditions. . Capsule toners exposed to such environmental conditions may be in a powder state immediately after storage, but after long-term storage, the oil-based solvent, which is a component of the binder contained in the capsule toner's core material, will be removed. When the toner oozes out through the shell and is present on the surface of the capsule toner, there is a problem in that significant aggregation occurs between the toner particles.

Problems similar to those described above may also occur with ordinary toner. In other words, toner usually contains polyolefin or paraffin wax as an anti-adhesive agent to prevent the toner from adhering to the fixing roll, etc., and such toner is exposed to the same environmental conditions as above. When stored in a developing device, the above-mentioned paraffin wax exudes and adheres to the surface of toner particles, which tends to cause aggregation between toner particles, and in such cases, the developed visible Problems such as a significant decrease in image resolution occur.

In order to solve this problem and improve the fluidity of the toner, a capsule toner (Japanese Unexamined Patent Publication No. 54-762
33 Publication) or a toner using dry process silica (silica produced by vapor phase oxidation of a silicon halide compound) which has been hydrophobically treated with a titanate coupling agent as a developer (Japanese Patent Application Laid-Open No. 123850/1985). is proposed. According to this, the fluidity of the toner immediately after production is improved due to the influence of the hydrophobically treated dry process silica. However, when such toners are stored in harsh environments with high humidity and high temperatures, they tend to ooze out into oil-based solvents or paraffin wax, resulting in aggregation between toner particles. Therefore, it cannot be said that the storage stability of the toner has been sufficiently improved.

[Objective of the Invention] An object of the present invention is to provide a developing toner having good powder properties and particularly good fluidity.

More specifically, the present invention provides a developing toner that hardly causes secondary aggregation and has good fluidity not only immediately after production but also after being stored in high-humidity, high-temperature environmental conditions. With the goal.

[Summary of the Invention] The present invention is directed to a developing toner characterized in that hydrophobically treated porous silica is attached to or contained on the surface of the toner particles.

[Effects of the Invention] Since hydrophobically treated porous silica is attached to or contained on the surface of the toner particles of the present invention, they exhibit good fluidity.

Further, the toner of the present invention exhibits good fluidity and excellent storage stability even after being stored under environmental conditions of high humidity and high temperature.

[Detailed description of the invention] First, capsule toner will be explained.

The capsule toner of the present invention has a basic structure consisting of a core material and an outer shell formed around the core material.

The core material of the capsule toner of the present invention includes a binder consisting of a polymer and an oily solvent, and a coloring material.

Among the components constituting the core material of the capsule toner of the present invention, there is no particular restriction on the polymer that is a component of the binder. Examples of polymers contained as the core material include polyolefin, olefin copolymer, styrene resin, and styrene resin. Gencopolymer, epoxy resin, polyester, rubber, polyvinylpyrrolidone, polyamide, coumaron/indene copolymer, methyl vinyl ether/maleic anhydride copolymer, amino resin, polyurethane, polyurea, acrylic acid ester homopolymer or copolymer, methacrylic Homopolymers or copolymers of acid esters, copolymer oligomers of acrylic acid and long-chain alkyl methacrylate, polyvinyl acetate, polyvinyl chloride, etc. can be mentioned, and the core material of the capsule toner of the present invention may be one of these alone, It may be contained in any mixed state.

Particularly preferred as the binder polymer are homopolymers or copolymers of acrylic esters, homopolymers or copolymers of methacrylic esters, or styrene-butadiene copolymers.

There are no particular restrictions on the oily solvent that is a component of the binder, but usually a high boiling point solvent (hereinafter also simply referred to as a high boiling point solvent) with a boiling point of 150°C or higher that can dissolve or moisten the above polymer is used. be done. Examples of high boiling point solvents include phthalate esters (e.g. diethyl 7
aliphatic dicarboxylic acid esters (e.g., diethyl malonate, dimethyl oxalate); phosphoric acid esters (e.g., tricresyl phosphate, tricresyl phosphate); citric acid esters (
Examples, 0-acetyl triethyl citrate, tributyl citrate)-benzoic acid esters (e.g., butyl benzoate, hexyl benzoate); aliphatic acid esters (
(e.g., hexadecyl myristate, dioctyl adipate); Alkylnaphthalenes (e.g., methylnaphthalene, dimethylnaphthalene, monoisopropylnaphthalene, diisopropylnaphthalene); Alkyl diphenyl ethers (e.g., 0-1m-1P-methyldiphenyl ether)
: Amide compounds of higher fatty acids or aromatic sulfonic acids (e.g., N,N-dimethyllauramide, N-butylbenzenesulfonamide); trimellitic acid esters (e.g., trioctyl trimellitate) and diaryl alkanes ( Examples, diarylmethane such as dimethylphenylphenylmethane, 1-phenyl-1-methylphenylethane, l-dimethylphenyl-1-phenylethane, 1
-ethylphenyl-1-phenylethane), etc.1 The core substance of the capsule toner of the present invention may contain these substances alone or in a mixed state. good.

The capsule toner of the present invention uses an oily solvent as a component of the binder, in addition to the above-mentioned high boiling point solvent, in a temperature range of 100 to 250°C that does not substantially dissolve or undo the polymer contained in the core material. It can also contain an organic solvent having a boiling point (hereinafter also simply referred to as a non-dissolving organic liquid). Examples of insoluble organic liquids include aliphatic saturated hydrocarbons, and the aliphatic saturated hydrocarbons may be a mixture of different carbon numbers.

The insoluble organic liquid can be mixed with the above-mentioned high boiling point solvent at any ratio, but generally the ffiMt ratio of high boiling point solvent/insoluble organic liquid is in the range of 971 to 1/9. Mixing is preferred.

Preferably, the binder is a composition comprising a polymer and a high boiling solvent, and also preferably a composition comprising a polymer, a high boiling solvent and a non-dissolving organic liquid.

The mixing ratio of the polymer and the high boiling point solvent is desirably in the range of 0.1 to 100 in fflff1 ratio of polymer/high boiling point solvent. Regarding the mixing ratio, the ffi amount ratio of [polymer ten high boiling point solvent]/insoluble organic liquid is 0.1-1.
It is desirable that the value be in the range of 00.

Carbon black, grafted carbon black, etc. are commonly used as coloring materials for electrophotographic toners, but various chromatic colorants such as blue, red, and yellow are also used. These known coloring materials can be used in the capsule toner of the present invention as well as the coloring materials.

The core material of the capsule toner of the present invention may contain magnetic particles. As the magnetic particles, known magnetic particles (magnetizable particulate matter) for magnetic toners can be used. Examples of such magnetic particles include magnetic particles made of elemental metals, alloys, or metal compounds such as cobalt, iron, or nickel. 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 functions as both the magnetic particles and the colored material.

The resin forming the outer shell of the capsule toner of the present invention is not particularly limited as long as it can form an outer shell around the core material dispersed in the form of oil droplets in an aqueous medium. Considering the characteristics of the outer shell resin,
Polyurea, polyurethane, polyamide or polyester are preferred; these resins may form the outer shell alone or as a mixture, and the outer shell of the capsule toner of the present invention comprises: It is preferable to use polyurea resin and/or polyurethane resin in consideration of the strength and flexibility of the outer shell. Furthermore, a composite wall containing polyamide resin can also be used.

The capsule toner of the present invention requires that aqueous-treated porous silica is attached to or contained on the surface of the outer shell that is likely to ooze around the core material as described above.

The porous silica used in the present invention usually has an internal surface area of 15 to 40% of the total surface area of the silica, preferably 20 to 30%. be.

Examples of such porous silica include silica produced by double decomposition of sodium silicate. That is, porous silica can be obtained by adding an acid, carbon dioxide, ammonium salt, etc. to an aqueous solution of sodium silicate to generate a precipitate by double decomposition reaction, and filtering, washing, and drying the precipitate.

Since such porous silica has a large internal surface area, it has particularly excellent oil absorption properties. Therefore, by attaching or containing the porous silica to the surface of the capsule toner, the oil-based solvent oozing through the outer shell of the capsule toner can be made porous, especially when the capsule toner is stored in a high-humidity, high-temperature environment. Silica can be easily absorbed. Therefore, the capsule toner can always maintain good fluidity even under various environmental conditions.

Preferably, the average particle size of the secondary particles of the porous silica is 60 mp or less.
If it is larger than g, the powder properties of the resulting capsule toner will be degraded, particularly the fluidity of the toner will be degraded.

Furthermore, such porous silica needs to be subjected to hydrophobic treatment. For example, a capsule toner in which 1M non-hydrophobically treated porous silica is adhered to or contains on the surface of the outer shell may exhibit good fluidity immediately after production, but such silica usually Because of its hygroscopic or water-absorbing properties, it absorbs moisture present in the air and increases its cohesiveness over time, so the toner powder itself gradually coagulates through the silica to form agglomerates, etc. Its powder properties and fluidity deteriorate. Therefore, in order to prevent the capsule toner from changing over time, it is necessary that the porous silica be hydrophobically treated.

Examples of such hydrophobically treated porous silica include porous silica treated with a silane coupling agent or a titanate coupling agent.

Specific examples of porous silica treated with a silane coupling agent include porous silica treated with dimethyldichlorosilane, hexamethyldisilazane, octyltrimethoxysilane and silicone oil.

Specific examples of porous silica treated with a titanate coupling agent include isopropyltriisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctylpyrophosphate) titanate, tetraisopropyl bis(dioctylphosphite) titanate, Tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl) bis(di-tridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, tris(dioctyl pyrophosphate) ) Ethylene titanate, isopropyltrioctanoyl titanate, isopropyl dimethacrylylisostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumylphenyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate , digmylphenyloxyacetate titanate and diinstearoylethylene titanate.

Among these, hydrophobically treated porous silica includes dimethyldichlorosilane treated silica, isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate or isopropyl tri (N-aminoethyl-aminoethyl).
Preference is given to titanate-treated silica.

Examples of methods for hydrophobically treating porous silica include:
Examples include a method of dry mixing porous silica and a coupling agent in a mixer such as a ball mill.

Note that in the present invention, the state in which the hydrophobically treated porous silica is attached to the surface of the outer shell of the capsule toner means that most of the hydrophobically treated silica is attached to the surface of the outer shell of the toner. This refers to the state in which the hydrophobically treated silica exists simply in contact with the surface of the shell16, and the state in which it is contained in the surface of the outer shell means that most of the hydrophobically treated silica particles are present in a state in which at least some of the particles are outside. It refers to the state of being buried near the surface of the shell, and the "attached or contained state" includes the above-mentioned attached state and buried state, and also includes an intermediate state of existence between the two. include.

There is no particular restriction on the content of the hydrophobically treated silica, but the hydrophobically treated silica is attached or contained within the range of 0.05 to 10% by weight based on the weight of the capsule toner to which no hydrophobically treated silica is attached or contained. It is preferable that 0.1
It is particularly preferable that the amount of Oi[ (If the amount exceeds %, the production cost will only increase and the effect will not improve much in many cases.

Next, regarding the method of manufacturing the capsule toner of the present invention,
A method for manufacturing a capsule toner having an outer shell of polyurethane resin and/or polyurea resin or a composite wall of polyurethane resin and/or polyurea resin and polyamide resin will be described as an example.

In an aqueous liquid, an outer shell made of polyurethane resin and/or polyurea resin is formed around a core substance containing a coloring material and a binder (and, if desired, magnetic particles, etc.) dispersed in the form of oil droplets. Methods for producing capsules are already known, and these known methods can also be used to produce the capsule toner of the present invention.

For example, an interfacial polymerization method can be mentioned as a method for manufacturing microcapsules using a polymerization reaction that can be used for manufacturing a capsule toner. Also,
Other examples of methods for producing microcapsules using polymerization reactions that can be used in the present invention include internal polymerization and external polymerization.

The outer shell made of polyurea resin and/or polyurethane resin is made of polyisocyanate such as diisocyanate, triisocyanate, tetraisocyanate, and polyincyanate prepolymer, polyamine such as diamine, triamine, and tetraamine, and diamine-7 group. It is known that the outer shell of microcapsules can be easily formed by reacting a prepolymer containing at least 1,000,000, piperazine and its derivatives, a polyol, etc. in an aqueous solvent by an interfacial polymerization method.

Further, a composite wall made of polyurea resin and/or polyurethane resin and polyamide resin, which is preferable as the outer shell of the capsule toner, is used, for example.

A composite wall made of polyurea resin and polyamide resin or a composite wall made of polyurethane resin and polyamide resin can be manufactured by the following method.

Composite walls made of polyurethane resin and polyamide resin,
For example, P of an emulsifying medium that uses polyincyanate, acid chloride, polyamine and polyol to form one reaction solution.
It can be prepared by an interfacial polymerization method consisting of H adjustment and then heating. Further, a composite wall made of a polyurea resin and a polyamide resin can be prepared by adjusting the pH of an aqueous medium that is a reaction solution using a polyisocyanate, an acid chloride, and a polyamine, and then heating it. Details of the method for producing composite walls made of these polyurea resins and polyamide resins and composite walls made of polyurethane resins and polyamide resins are described in JP-A-58-66948. Such composite-walled shells are particularly suitable for forming toner capsules containing magnetic particles within the core material.

The monomers involved in the polymerization reaction for forming the outer shell vary depending on the resin forming the outer shell.

Two or more types of monomers can also be used in combination. Examples of such monomer combinations include at least one difunctional compound containing a group selected from the group consisting of incyanato groups, bischloroformate groups, acid chloride groups, and sulfonyl chloride groups; Combinations with at least one compound selected from the group consisting of monovalent amines, polyvalent alcohols, polyvalent amines, and polyvalent carboxylic acids can be mentioned.

After forming the microcapsules by forming an outer shell around the core material, the microcapsules are separated from the liquid phase, washed with water, and then dried.

This separation and drying operation is usually carried out by heating and drying a slurry containing microcapsules.

Note that the separated and dried microcapsules can be further subjected to heat treatment. This heat treatment particularly improves the powder properties of the capsule toner. Heat treatment is 50-300
Preferably, it is carried out at a temperature in the range of 80-1°C.
It is particularly preferable to heat at a temperature in the range of 50°C. The heating time can be determined as appropriate depending on the heating temperature and the type of core material used, but it is usually 10 minutes to 40 minutes.
Heat for 8 hours, preferably 2 to 24 hours.

There are no particular limitations on the equipment and instruments used for the heat treatment, and examples of the equipment include electric furnaces, Matsufuru furnaces, hot plates, electric dryers, fluidized bed dryers, infrared dryers, and the like.

Incidentally, if desired, a total dioptric dye, a charge control agent such as nigrosine, or any other additive substance may be added to the outer shell of the capsule toner of the present invention. These additive substances can be incorporated into the outer shell of the capsule toner at any time, such as when the outer shell is formed or after the capsule toner is separated and dried.

On the other hand, the manufacturing method for ordinary non-encapsulated toner is already known, and the known method can be used for manufacturing the non-encapsulated toner of the present invention.

Examples of the binder (binding component) include homopolymers of styrene and its substituted products, styrenic copolymers, and commonly used resin components. These can be used alone or in combination.

As the stone Buddha material, known materials such as those exemplified in the capsule toner mentioned above can be used.

A predetermined amount of hydrophobically treated porous silica is mixed into the capsule toner or ordinary toner thus prepared. There are no particular restrictions on the mixing method, and commonly used mixers, V-type mixers, etc. can be used.

The obtained toner exhibits excellent powder properties, especially its fluidity.

In the following margins, Examples and Comparative Examples of the present invention will be shown. In the Examples and Comparative Examples, "%" means "% by weight" unless otherwise specified.

[Example 1] 50% by weight of polyisobutyl methacrylate (trade name Niacrybase, MM-2002-2 Nitokura Kasei ■!l)
Containing l-isopropyl-phenyl-2-phenylethane and l5opar eyelid H (aliphatic saturated hydrocarbon mixture:
A dispersion liquid (magnetic ink) was prepared by cross-dispersing 40 g of a solution prepared by mixing Exxon Chemical (manufactured by Exxon Chemical ■) at a weight ratio of 6:5 and 40 g of magnetite magnetic particles in an automatic mortar.

Separately, add an addition compound of 3 moles of xylylene diisocyanate and 1 mole of trimethylolpropane to 20 g of ethyl acetate (
Product name: Taganate D-11ON (manufactured by Takeda Pharmaceutical Company)
A solution was prepared in which 9.9 g of 9.9 g was dissolved, and this solution was mixed with the above-mentioned dispersion liquid (B & magnetic ink) to prepare an oily phase. ) was prepared while controlling the liquid temperature to 25°C or lower.

Methylcellulose (methoxy21!iZf conversion degree: 1°8
, average molecular weight: 15,000) to prepare an aqueous medium by adding 0.2 g of diethylenetriamine to 200 g of a 4% aqueous solution of the compound (average molecular weight: 15,000), and the temperature of this aqueous medium was cooled to 15°C.

The oily phase mixed liquid was emulsified and dispersed in this aqueous medium to obtain an oil-in-water emulsion in which the average size of oil droplets in the emulsion was about 124 m.

Approximately 10 minutes after making the emulsion a, 50 g of a 2.5i swelling% aqueous solution of diethylenetriamine was gradually added dropwise.
The mixture was stirred in a constant temperature bath at 0° C. for 3 hours to complete encapsulation.

The resulting microcapsule dispersion was allowed to stand to allow the microcapsules to settle, and the upper aqueous layer was discarded, with washing water added instead, stirred, and allowed to stand.

This washing operation was repeated 20 times to remove methylcellulose and the like adhering to the surface of the microcapsules. The washed microcapsule slurry was dried in an oven set at 100° C. to obtain a capsule toner. This capsule toner was treated with dimethyldichlorosilane using porous silica (trade name: NI320DS: 30% internal surface area, average particle size 18 m IL: manufactured by Nippon Aerosil ■), and the capsule toner fI! 1% by weight based on the amount was added and mixed.

This capsule toner had each capsule particle existing independently and exhibited very smooth fluidity.

[[Il Property Evaluation] What is the evaluation of the fluidity of the capsule toner obtained above? !
) The apparent density and tap density of the capsule toner immediately after manufacture (before storage) and after storage for 16 hours at 110°C and 20% RH were determined by these values, and by the compression ratio calculated according to the following formula. evaluated.

(Tap density) - (apparent density) Compression ratio = −−−−−−−−−−−−−−−−−−−−
--(Tap density) The apparent density (g/cc) is measured by passing the capsule toner through a conical metal sieve (top diameter 72 mm, bottom mesh surface diameter 50 mm, height 50 mm, mesh
The capsule toner was placed in a cylindrical container (diameter: 58 mm, height: 75 mm) by slowly vibrating a metal sieve, and the weight of the collected product was measured.

To measure the tap density (g/cc), place the capsule toner in the same conical metal sieve as above, vibrate it slowly in the same manner as above, and place the capsule toner in the same cylindrical container as above. After the capsule toner was dropped and the cylindrical container was violently vibrated to solidify the capsule toner, the weight of the resulting aggregate was measured.

The results are shown in Table 1.

[Comparative Example 11 Implemented except that dry method silica treated with dimethyldichlorosilane (trade name: Aerosil R972, average particle size 16 mμ manufactured by Nippon Aerosil ■) was used instead of porous silica treated with dimethyldichlorosilane. A capsule toner was obtained in the same manner as in Example 1. In this capsule toner, each capsule particle existed independently and exhibited smooth fluidity.

The fluidity of the obtained capsule toner was evaluated in the same manner as in Example 1.

The results are shown in Table 1.

[Example 2] The same procedure as in Example 1 was used except that porous silica treated with isopropyltriisostearoyl titanate (trade name: Prenact TTS: Ajinomoto ■5!) was used instead of porous silica treated with dimethyldichlorosilane. A capsule toner was obtained in the same manner as in the above procedure.In this capsule toner, each capsule particle existed independently and exhibited smooth Iit mobility.

As for the obtained capsule toner, tIt is the same as in Example 1.
We evaluated the dynamics.

The results are shown in Table 1.

[Comparative Example 2] Instead of porous silica treated with isopropyl triisostearoyl titanate, dry process silica (trade name: Aerosil #130, manufactured by Nippon Aerosil ■, average particle size 20 mμ) was treated with isopropyl triisostearoyl titanate. A capsule toner was obtained in the same manner as in Example 2, except that a capsule toner was used.

In this capsule toner, each capsule particle existed independently and exhibited smooth fluidity.

The fluidity of the obtained capsule toner was evaluated in the same manner as in Example 2.

The results are shown in Table 1.

Table 1: Appearance before storage: Density (g/cc) 0.47 0-46 0.
46 0.47 Tap density (g/cc) 0.74
0.75 0.75 0.73 Compression ratio 01
6 0j9 0. :19 0.36 Apparent density (g/c
c) 0.48 G, 47 0.40 0.39 Tap density (g/cc) 0.74 0.75 0.7
1 0.70 compression ratio 0.35 0.37
0.44 (1,44As is clear from the results shown in Table 1, before storage, the apparent density, tap density, and compression ratio values are the same as those of the hydrophobically treated porous silica shell. There is almost no difference between the capsule toners of the present invention (Examples 1 and 2) and the comparative capsule toners (Comparative Examples 1 and 2) in which 110 ℃, 20%R) 1'''c16
After being stored for a period of time, the compression ratio of the capsule toner of the present invention has almost no difference from the value before storage;
The capsule toner for comparison has an increased compression ratio value after storage. There are various reasons why the compression ratio has increased, and one of the reasons is the occurrence of secondary aggregation between toner particles. Namely.

Tap density, apparent density and compression ratio are t of toner particles.
It is closely related to tap density, and if each toner particle exists independently and maintains good fluidity even after storage as before storage, tap density and Apparently, the value of the difference in density does not change before and after storage, so the compression ratio does not change from the above calculation formula. However, after storage, secondary IM collection occurs between toner particles, and the toner When the fluidity of particles decreases, the value of the difference between the tap density and the apparent density tends to increase, and the compression ratio increases. Therefore, it is clear that the capsule toner of the present invention has an almost constant compression ratio before and after storage, has good fluidity even under harsh environmental conditions of high humidity and high temperature, and has excellent storage stability. be.

On the other hand, the compression ratio of the capsule toner for comparison increases after storage, and it can be said that the storage stability is inferior to the capsule toner of the present invention, especially under harsh environmental conditions such as high temperatures.

Claims (1)

[Scope of Claims] 1. A developing toner characterized in that hydrophobically treated porous silica is attached to or contained on the surface of the toner particles. 2. The developing toner according to claim 1, wherein the hydrophobically treated porous silica is dimethyldichlorosilane treated silica. 3. Hydrophobically treated porous silica is made of isopropyl triisostearoyl titanate, isopropyl tris (
Claims characterized in that the porous silica is treated with at least one titanate coupling agent selected from the group consisting of dioctyl pyrophosphate) titanate and isopropyl tri(N-aminoethyl-aminoethyl) titanate. The developing toner according to item 1. 4. The developing toner according to claim 1, wherein the porous silica is porous silica produced by double decomposition of sodium silicate. 5. A patent characterized in that the content of hydrophobically treated porous silica is within the range of 0.05 to 10% by weight based on the weight of the toner to which the porous silica is not attached or does not contain. Developing toner according to claim 1. 6. The developing toner according to claim 1, wherein the average particle diameter of the hydrophobically treated porous silica primary particles is 60 mμ or less. 7. The developing toner according to claim 1, wherein the toner is a capsule toner, and the core substance of the capsule toner contains a binder containing an oily solvent. 8. The binder is a polymer, a high boiling point solvent with a boiling point of 150°C or higher that can dissolve or swell the polymer, and 1 that does not substantially dissolve or swell the polymer.
8. The developing toner according to claim 7, which is a composition containing three organic solvents having a boiling point within the range of 00 to 250°C.