JPH0470847A - Toner for electrophotography - Google Patents

Abstract

PURPOSE:To improve the flowability, electrostatic chargeability and durability of a toner by incorporating fine metal oxide powder surface-treated with a treating agent for rendering hydrophobic property and a titanate coupling agent. CONSTITUTION:This toner is composed essentially of a binding resin, a colorant and fine metal oxide powder surface-treated with a treating agent for rendering hydrophobic property and a titanate coupling agent. Fumed silica or alumina obtd. by vapor phase hydrolysis may be used as the metal oxide powder. The treating agent may be an organosilicon compd. such as hexamethyldisilazane and the coupling agent may be isopropyltriisostearoyl titanate.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a toner for developing electrostatic latent images formed in electrophotography, electrostatic printing, electrostatic recording, etc. More specifically, the present invention relates to a negatively charged toner used in digital writing electrophotography and the like.

[Conventional technology]

Conventionally, as an electrophotographic method, US Pat.
Various methods are known, as described in Japanese Patent No. 748, etc., but in general, a photoconductive substance is used to form an electrical latent image on a photoconductive support by various means. The latent image is then developed with toner to obtain a visible image, or if necessary, the powder image is transferred to paper or the like and then fixed by heat, pressure, solvent vapor, etc. to obtain a visible image. be.

In electrophotography, in order to stably form visible images of good quality over a long period of time, appropriate conditions are actually required, and toner is no exception.

Toners are generally made of powder of electroscopically colored particles in which a coloring agent, a polarity control agent, etc. are dispersed in a thermoplastic binder resin. In order to form a toner, it is necessary that the toner has high fluidity. Therefore, in the past, metal oxide fine powder such as silicon dioxide has been added and mixed to toner.

Incidentally, since metal oxide fine powder is hydrophilic as it is, toner to which it is added has a reduced chargeability due to the influence of moisture in the air.

Therefore, it has been proposed to use hydrophobized metal oxide fine powder (for example, JP-A-46-5782;
(See Japanese Patent Application Laid-open Nos. 48-47345 and 48-47346, etc.). Specifically, for example, silicon dioxide particles and an organosilicon compound such as dimethylchlorosilane are cocurrently fed into a fluidized bed reaction vessel heated with water vapor in an inert gas such as nitrogen gas. Fine powder of silicon dioxide particles is used, in which the silanol groups on the surface of the particles are made hydrophobic by reacting with an organic silicon compound.

However, although the metal oxide fine powder obtained in this way has been made into water-melted water, the degree of hydrophobization is not sufficient, and for example, it becomes cohesive under high temperature and humidity. Not only does the fluidity of the toner decrease, but also the charge tends to leak due to moisture absorption, so the amount of charge on the toner particles decreases, which may lead to a decrease in the quality of the visible image. Furthermore, when hydrophobized metal oxide fine powder is used, it is difficult to control the chargeability, and the amount of charge increases especially in low humidity, resulting in a decrease in image density.
It has the disadvantage of being highly dependent on the environment. Additionally, the hydrophobized metal oxide fine powder is quite hard, and therefore tends to damage the electrostatic image support. Particularly when the electrostatic charge image support is made of a material with relatively low hardness, such as an organic photoconductive material, the damage is noticeable and tends to cause toner filming on the electrostatic charge image support and poor cleaning. Become.

Furthermore, Japanese Patent Publication No. 1-43950 proposes a method using fine silica powder treated with a titanate coupling agent, but this method not only fails to provide sufficient negative chargeability but also causes fluidity. The effect of imparting image quality was extremely small, and the image quality of visible images could not be sufficiently improved.

[Problem to be solved by the invention]

The present invention has been made in view of the above-mentioned state of the prior art, and its purpose is to provide good fluidity, excellent image quality, less environmental dependence, and excellent chargeability. An object of the present invention is to provide an electrophotographic toner having the following properties. Another purpose is to provide an electrophotographic toner that has excellent durability and provides stable performance even after repeated use over a long period of time. No toner filming occurs.
It is an object of the present invention to provide an electrophotographic toner that can perform good cleaning.

[Means to solve the problem]

As a result of extensive studies, the present inventors found that the above problem was solved by using fine metal oxide powder whose surface was treated with both a hydrophobizing agent and a titanate coupling agent as a component of a toner for developing an electrostatic image. I discovered what could be achieved if

That is, according to the present invention, an electrophotographic toner comprising at least a binder resin and a colorant is characterized in that it contains metal oxide fine powder that has been surface-treated with a hydrophobizing agent and a titanate coupling agent. An electrophotographic toner is provided.

The present invention will be explained in more detail below.

The electrophotographic toner of the present invention is characterized in that gold ijL oxide fine powder surface-treated with both a hydrophobizing agent and a titanate coupling agent is added and mixed with toner particle powder.

Therefore, according to the present invention, the fluidity and moisture resistance of the toner are sufficiently ensured even when images are repeatedly formed;
As a result, it becomes possible to form a good visible image, and damage to the electrostatic image support is significantly suppressed.

Next, an outline of the metal oxide fine powder surface-treated with two types of hydrophobizing agents used in the present invention will be described.

The metal oxide fine powder is selected from fumed silica, alumina, titania, or silicon and aluminum fluoride obtained by gas phase hydrolysis, and contains at least 5
It has a specific surface area of 0rd/g or more, and the primary particles are 50nm.
Those finer than the above are preferably used.

Examples of such metal oxide powders include "Aerosil 200J" manufactured by Nippon Aerosil Co., Ltd. and "Aerosil 200J" manufactured by Degussa AG, West Germany.
Preferred examples include "Aluminum Oxide C", "Titanium Oxide P25", and "Aerosil MOX170J".

As the hydrophobizing agent for surface treating the metal oxide fine powder, organic silicon compounds are particularly preferably used. The hydrophobizing agent is generally capable of reacting with or adsorbing OH groups or adsorbed water on the surface of the metal oxide fine powder to form a coating. In this case, the hydrogen atoms of the OH groups or adsorbed water present on the surface of the metal oxide fine powder are substituted with the organic groups of the hydrophobizing agent, and the hydrophobizing agent interacts with the metal oxide fine powder through oxygen atoms. It will be combined.

Examples of the hydrophobizing agent suitably used in the present invention include trimethylmethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, vinyltrimethoxysilane, 3-chloropropyltrimethoxysilane, vinyletriacetoxysilane, hexamethyl Examples include organosilicon compounds such as disilazane, hexamethyldisiloxane, octamethylcyclotetrasiloxane, and dimethylsilicone oil.

The titanate coupling agent used in the present invention reacts with or adsorbs hydroxyl groups or adsorbed water on the surface of the metal oxide fine powder. *It is an organic titanium compound that can form a coating on the surface of powder. Examples of such organic titanium compounds include the following.

Isoprobyl triisostearyl titanate Isopropyrutrioctanoyl titanate Isopropyl diisostearyl cumyl phenyl titanate Isoprobyl distearyl methacrylic titanate Isoprobyl dimethacrylic isostearyl titanate Isoprobyl tridodecyl benzenesulfonyl titanate Isoprobyl diisostearoyl acrylic Titanate Isoprobyl isostearoyl diacrylic titanate Isopropyl tri(dioctyl phosphate) titanate Isopropyl tri n-stearoyl titanate Isopropyl 4-7 Minobenzenesulfonyl di(dodecylbenzenesulfonyl) titanate Isopropyl trimethacrylic titanate Isopropyl tricumylphenyl tatinate Isopropyl di(4-7) 7minobenzoyl) isostearoyl titanate isopropyl tri(dioctyl piophosphate) titanate isopropyl triacrylic titanate isopropyl tri(N,N-dimethyl-dithylaminotitanate isopropyl tri(N-ethylamino-ethylamino)
Titanate isoprobyl trianthranyl titanate isoprobyl octyl, butyl pyrophosphate titanate isopropyl di(butyl, methyl birophosphate)
Titanate tetra(di(ditridecyl) phosphite) Titanate tetra(di(ditridecyl) phosphite) Titanate tetra(2,2 diallyloxymethyl-1-butoxy) di(ditridecyl) phosphite Titanate diisostearyloxyacetate titanate isostearylmethacryloxyacetate titanate isostearoylacryloxyacetate titanate di(diophthalphosphate)oxyacetate titanate 4-aminobenzenesulfonyldodecylbenzenesulfonyloxyacetate titanate dimethacryloxyacetate titanate dicumyl Feltoxyacetate titanate 4-aminobenzoylisostearoyloxyacetate titanate di(dioctylpyrophosphate)oxyacetate titanate diacryloxyacetate titanate di(octyl,
butyl pyrophosphate) oxyacetate titanate diisostearoyl ethylene titanate isostearoyl methacryl ethylene natanate di(dioctyl phosphate) ethylene titanate 4-aminobenzenesulfonyldodecylbenzenesulfonyl ethylene titanate dimethacrylic ethylene titanate 4-aminobenzoyl isostearoyl ethylene titanate di(dioctyl pyrophosphate) (pyrophosphate) ethylene titanate diacrylic ethylene titanate dianthranyl ethylene titanate di(butyl, methyl pyrophosphate) ethylene titanate These titanate coupling agents may be used alone or in a mixed system of two or more. As a method for treating the above-mentioned fine powder with a titanate coupling agent, either a dry method or a wet method can be adopted. For example, metal oxide fine powder and an appropriate amount of titanium-based coupling agent are put into a mixer such as a Henschel mixer or a ball mill, and mixed dry, or after the titanium-based coupling agent is dissolved in an appropriate solvent. Various methods are used, such as a method in which fine metal oxide powder is added, mixed, and the solvent is removed.

In the present invention, the amount of the image processing agent used to hydrophobize the metal oxide fine powder is preferably 1 to 20% by weight.

If it is less than 1% by weight, the effect of the treatment will not be fully expressed, and if the
When the weight exceeds 0 weight XX, the effect is saturated. Metal oxide fine powder whose surface has been treated with both a hydrophobizing agent and a titanate coupling agent can be placed on a grounded aluminum plate at a temperature of ±0 to 50%.
It has a charge of 0V (negative chargeability), completely floats in pure water, and has hydrophobicity to the extent that it can be wetted for the first time in a methanol solution of 35 to 50 volumes 2.

The content of the hydrophobized metal oxide fine powder is preferably in the range of 0.01 to 10% by weight, and most preferably in the range of 0.1 to 5% by weight, based on the total amount of the toner. By sufficiently mixing and dispersing it in other components within this range, the fluidity of the toner can be significantly improved while maintaining negative chargeability. Further, the degree of hydrophobicity of the hydrophobically treated metal oxide fine powder is preferably 40% or more, and more preferably 50% or more.
% or more is more preferable.

As described above, the electrophotographic toner of the present invention has good fluidity and excellent fluidity because it contains metal oxide fine powder that has been surface-treated with both a hydrophobizing agent and a titanate coupling agent. It exhibits excellent moisture resistance and stability over time.
Moreover, it has the effect of suppressing damage to the electrostatic image support. That is, the hydrophobized metal oxide fine powder used in the present invention has a part with an organic group not containing the titanium element and a part with an organic group containing the titanium element on its surface via an oxygen atom. By having this together, the effects described above can be obtained. In other words, on the surface of the metal oxide fine powder, there is a part having an organic group containing a titanium element in a certain proportion, so that the negative chargeability is not too high and has good and stable negative chargeability. can have. Therefore, the metal oxide fine powder of the present invention has a considerably high degree of hydrophobicity, and as a result, it is thought that the toner as a whole has greatly improved moisture resistance and has appropriate negative chargeability and fluidity.

The toner powder in the present invention is not particularly limited, and any toner powder may be used.

As mentioned above, toner powder generally has a colorant and, if necessary, additives such as a polarity control agent dispersed in particles mainly composed of a binder resin, and the average particle size is usually 5 to 5. 20. That's about it.

As the binder resin for the toner of the present invention, known resins for toners can be used. For example, monopolymers of styrene and its substituted products such as polystyrene, poly-p-styrene, and polyvinyltoluene, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers,
Styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-methacrylic acid Ethyl copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer Polymers, styrenic copolymers such as styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-maleic acid copolymers, styrene-maleic ester copolymers, polymethyl methacrylate, polybutyl methacrylate, poly Vinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyurethane, polyamide, polyester resin, epoxy resin, polyvinyl butyral, polyacrylic resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or aliphatic hydrocarbon resin, aromatic Group petroleum resins, chlorinated paraffins, paraffin waxes, etc. can be used alone or in combination.

As the colorant, all known colorants for toners can be used. Examples of black colorants include carbon black, aniline black, furnace black,
Lamp black etc. can be used. Examples of cyan colorants include phthalocyanine blue and methylene blue.
Victorian blue, methyl violet, aniline blue, ultramarine blue, etc. can be used. As the magenta coloring agent, for example, Rhodamine 6G Lake, Watching Red, Rose Bengal, Rhodamine B, Alizarin Lake, etc. can be used. As the yellow coloring agent, for example, chrome yellow benzidine yellow, Hansa yellow, naphthol yellow, molybdenum orange, quinoline yellow, tartradon, etc. can be used.

Furthermore, these toners may contain small amounts of polarity control agents, such as dyes and pigments, charge control agents, etc., in order to provide more efficient charging. Examples of polarity control agents include metal complex salts of monoazo dyes, nitrofumic acid and its salts, salicylic acid, naphthoic acid, and dicarboxylic acids such as Co and C.
Examples include metal complexes such as r, Fe, sulfonated copper phthalocyanine pigments, nitro groups, styrene oligomers into which halogens have been introduced, chlorinated paraffins, and melamine resins.

The toner of the present invention may also contain other fluidizing agents such as colloidal silica, fine powder of metal oxides such as titanium oxide and aluminum oxide, abrasives such as silicon carbide, and lubricants such as fatty acid metal salts. etc. may be included.

The toner of the present invention can be used as either a one-component developer or a two-component developer mixed with a carrier. When used as a two-component developer,
As the carrier, conventionally known carriers can be used. for example,
Iron powder, nickel powder, ferrite powder, magnetite powder, glass beads with a particle size of about 20 to 200 tones, or these are used as a core material, and the surface is coated with fluorine resin, silicone resin, styrene resin, or acrylic resin. Those coated with resin such as can be used.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to the following examples, but the present invention is not limited thereto. Note that "parts" in the description mean parts by weight.

In the following examples, the organosilicon compound-based hydrophobizing agent and titanate-based coupling agent used to surface-treat the metal oxide fine powder are shown in Tables 1 and 2, respectively.

Table 1 Table 2 Example 1 Styrene-〇-butyl methacrylate copolymer (70:
30) as a binder resin, 100 parts of it, 5 parts of carbon black r#-4U (manufactured by Mitsubishi Kasei Co., Ltd.) and 2 parts of a polarity control agent [Bontron 5-34] (manufactured by Orient Chemical Industry Co., Ltd.) were melt-kneaded. A toner powder having an average particle size of about 11 μs was produced by a conventional method of cooling, pulverizing, and classifying. (hereinafter referred to as toner powder)
Put 20 parts of 00J (manufactured by Nippon Aerosil Co., Ltd.) into a high-speed rotating mixer, and while stirring at 8000 rpm, add a solution prepared by diluting 0.5 part of titanate coupling agent (B-) with 20 parts of 90% ethanol. Transfer the mixed powder liquid to a vat and heat it at 110°C under a nitrogen gas atmosphere.
The ethanol solvent was removed by heating and drying at 'C for 1 hour.

The obtained powder was put into a high-speed rotating mixer again, and a solution prepared by diluting 2 parts of the hydrophobizing agent (A to ■) with 20 parts of hexane was dispersed in the same manner as above, and the obtained powder was heated at 150°C. The mixture was heated and stirred for 4 hours to obtain fumed silica (2) which had been made hydrophobic and whose surface had been modified with a titanate coupling agent. Next, 01 part of the obtained fumed silica was added to 100 parts of the toner powder and mixed using a Henschel mixer to obtain a toner of the present invention (hereinafter referred to as toner (2)).

Example 2 Alumina [aluminum oxide Cl (manufactured by Deguza, West Germany) having a specific surface area Loom/g was treated with a hydrophobizing agent (A
-■) and a titanate coupling agent (B-■) to obtain hydrophobized alumina (2). Next, 01 parts of the obtained alumina is added and mixed to 100 parts of the toner powder using a Henschel mixer,
A toner of the present invention was obtained (hereinafter referred to as toner ①).

Example 3 Titanium oxide P-25J (manufactured by Deguza, Germany) having a specific surface area of 50 m/g was treated with a hydrophobizing agent (A-■) and a titanate coupling agent (B-■).
) to obtain titania (2) which was surface-treated with both methods and subjected to hydrophobization treatment. Next, 1 part of the obtained Chiku 2 Fu was added to 100 parts of the toner powder and mixed using a Henschel mixer to obtain the toner of the present invention (hereinafter referred to as toner ①).

).

Example 4 Iron oxide of silicon and aluminum having a specific surface area of 170 m/g “Anilosil MOX170J (manufactured by Deguza, West Germany)
was surface-treated with both a hydrophobizing agent (A-■) and a titanate coupling agent (B-) to obtain a hydrophobized iron oxide of silicon and aluminum (2). Next, 1 part of the obtained silicon-aluminum co-oxide (2) was added to 100 parts of the toner powder and mixed using a Henschel mixer to obtain a toner of the present invention (hereinafter referred to as toner (2)).

Example 5 Fumed silica "Aerosil 200J (manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m/g was treated with a hydrophobizing agent (A-■) and a titanate coupling agent (B-■).
) was surface-treated with both methods to obtain hydrophobized fumed silica (■). Next, 0,085 parts of the obtained fumed silica was added to 100 parts of the toner powder and mixed using a Henschel mixer to obtain a toner of the present invention (hereinafter referred to as toner (2)).

Example 6 Fumed silica "Aerosil 200J (manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m/g was treated with a hydrophobizing agent (8-■) and a titanate coupling agent (B-■).
) was surface-treated with both methods to obtain hydrophobized fumed silica (■). Next, 0.5 part of the obtained fumed silica (2) was added to 100 parts of the toner powder and mixed using a Henschel mixer to obtain a toner of the present invention (hereinafter referred to as "toner (2)").

Comparative Example 1 Fumed silica "Aerosil 200J" (manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m/g was surface-treated with only a hydrophobizing agent (A-■) to obtain a hydrophobized fumed silica (■). 01 parts of the obtained fumed silica was added to 100 parts of the powder and mixed using a Henschel mixer to obtain the toner of the present invention (hereinafter referred to as toner (2)).

Comparative Example 2 Fumed silica r Aerosil 200J (manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 r&/g was surface-treated with only a titanate coupling agent (B-■) to obtain hydrophobized hummed silica (■). Next, 0 parts of the obtained fumed silica was added to 100 parts of the toner powder.
One part was added and mixed using a Henschel mixer to obtain a toner for comparison (hereinafter referred to as toner ■).

[Live action test]

96 parts of a ferrite carrier was mixed in a ball mill with 4 parts each of toners (1) to (2) prepared as described above to prepare developers (1) to (2).

Next, an image test was conducted for each of the above-mentioned developers ① to ② to evaluate the image quality. For the image test, a Ricoh IMAGIO-320 digital copying machine was used. The amount of charge of each toner during the test (initial period and after continuous copying of 10,000 sheets) was measured by a blow-off method. Also, 35
Under high humidity environment of 90% RH at ℃ and 15% RH at 10℃
We also conducted tests in a low-humidity environment to evaluate environmental stability. The fluidity of the developer was also evaluated. The results are summarized in Table 3.

The fluidity of the developer was determined by a flow test using a funnel having an oil filtration diameter of 5 mm.

O: Liquidity is very low.

O: Excellent fluidity.

Δ: Fluidity is slightly poor.

×: Poor fluidity.

〔effect〕

As described above, since the toner of the present invention has good fluidity, high-quality images with excellent gradation reproducibility can be obtained. Even after continuous copying, an image with the same quality as the initial image can be obtained, with no change in the amount of negative charge, little environmental variation, and a clear image. Also.

Leaning can be performed satisfactorily without causing toner filming on the electrostatic image support.

Patent applicant Rico Co., Ltd.

Claims (2)

[Claims] (1) An electrophotographic toner comprising at least a binder resin and a colorant, which contains metal oxide fine powder surface-treated with a hydrophobizing agent and a titanate coupling agent. (2) The electrophotographic toner according to claim 1, wherein the metal oxide fine powder is one selected from the group consisting of silica, alumina, titania, and co-oxides of silicon and aluminum.