JP3278278B2 - Hydrophobic titanium oxide fine powder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrophobic titanium oxide type fine powder useful as an external additive for dry electrophotographic toner.

[0002]

2. Description of the Related Art Conventionally, fine powders have been used in various fields, but the fine powders are surface-treated according to the fields.

In the field of electrophotography, silica fine powder, titanium oxide fine powder and the like are used as external additives for toners for developing electrostatic images, in order to stabilize the electrophotographic characteristics of the toner in each environment. A fine powder that has been subjected to a hydrophobic treatment is also used. In particular, titanium oxide fine powder has been attracting attention as an external additive for toner.

Titanium oxide is obtained by neutralizing an aqueous titanium sulfate solution and calcining the resulting precipitate, or by decomposing and oxidizing titanium tetrachloride at a high temperature, or titanium. Those obtained by hydrolyzing or thermally decomposing alkoxide are known. It is known that these titanium oxides have an anatase type or rutile type crystal system and are amorphous. Hydrophobic titanium oxide is produced by treating these titanium oxides with a hydrophobizing agent such as a silane coupling agent. Since conventional titanium oxide tends to have low reactivity with a hydrophobizing agent, development of highly reactive titanium oxide-based fine powder has been desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydrophobic titanium oxide-based fine powder treated with a titanium oxide-based fine powder having a high reactivity with a hydrophobizing agent.

An object of the present invention is to provide a hydrophobic titanium oxide-based fine powder treated with an amorphous titanium oxide-based fine powder which is difficult to crystallize.

An object of the present invention is to provide a hydrophobic titanium oxide type fine powder which is not easily affected by environment such as temperature and humidity and which is useful as a fluidity improver.

An object of the present invention is to provide a hydrophobic titanium oxide-based fine powder useful as an external additive for electrophotographic toner.

[0009]

[In the formula, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents a hydrocarbon group selected from an alkyl group, a vinyl group, a glycidoxy group and a methacryl group, and n is 1 to 3 Indicates an integer]

The amount of Si in terms of SiO ₂ obtained by treating with the alkoxysilane compound represented by
The present invention relates to a hydrophobic titanium oxide-based fine powder, which is characterized by comprising the hydrophobic fine powder.

The present inventors have diligently studied the fluidity, charge stability, transferability, cleaning property and the like of the toner for developing an electrostatic charge image. As a result, the fine powder of the above composition as an external additive has a fluidity. It has been found to be extremely effective in terms of imparting and stabilizing charging.

This cannot be achieved with a generally known inorganic oxide such as titanium oxide as a fluidity improver.

The reason for this is that the conventional titanium oxide production method requires sintering, hydrolysis, or thermal decomposition steps at high temperatures, so that the particles are easily coarsened and the obtained titanium oxide particles are of anatase or rutile type. It becomes easy to take a crystal structure.

On the other hand, TiO ₂ component and Ti(OR)
m(OH)n component (wherein m and n are integers of 0 to 4 and R satisfying m+n=4 represents a saturated or unsaturated cyclic or acyclic hydrocarbon group) as a main component. With the fine powder of the composition described above, coarsening of the particles is suppressed, the coalescence of the primary particles is small, and good fluidity is imparted to the toner.

In addition, since the fine powder of the present invention contains a titanium alkoxide and a titanium hydroxy component, the active Ti--OH on the surface of the fine powder is more than that of ordinary rutile type, anatase type or amorphous titanium oxide particles. It has much more groups, and therefore exhibits good dispersibility when dispersed in the toner, and when it is attached to the toner surface, the adhesive force between the binder resin and the fine powder is high, and the durability causes It is possible to maintain the initial properties for a long time even in long-term durability, without the fine powder detaching and contaminating the carrier surface or the drum.

Further, since the fine powder of the present invention comprises the TiO ₂ component and the Ti(OR)m(OH)n component, when the fine powder is dispersed in the toner and frictionally charged with the carrier,
The Ti(OR)m(OH)n component in the fine powder serves as a kind of leak point, which greatly functions to suppress an excessive amount of charge, particularly under a low temperature and low humidity condition, and a stable amount of charge can be obtained. Particularly when a polyester resin is used as the binder resin, the effect is great.

Further, the treated fine powder used in the present invention is
When used in a color toner for forming a full-color image, the primary particles are small and the secondary agglomerates are very small, so that external addition to the colorant-containing resin particles can be performed uniformly and the light in visible light Excellent transparency and clear OH
A P image is obtained. This is something that cannot be achieved with conventional titanium oxide particles.

Further, when treating the surface of the fine powder with, for example, a silane-based organic compound, conventional rutile-type, anatase-type or amorphous titanium oxide fine particles have a small amount of active Ti-OH groups on the surface and are sufficiently treated. What could not be achieved is that the fine powder of the present invention is
The reaction between the (OR)m(OH)n component and the treating agent proceeds smoothly, and moreover, the surface can be uniformly treated without forming aggregates, and the degree of hydrophobicity is targeted. You can fully raise it to the level. This makes it possible to favorably stabilize the charge under high temperature and high humidity.

In the present invention, in particular, a TiO ₂ component and Ti produced by thermally decomposing a volatile titanium compound such as titanium alkoxide at a relatively low temperature of 600° C. or lower in a gas phase, preferably 200 to 400° C. (OR)m(O
H) Fine powder of a composition containing the n component as a main component is preferable.

Particularly, after vaporizing or atomizing a volatile titanium compound at a relatively low temperature of 200 to 400° C., it is hydrolyzed (or may be thermally decomposed) in the presence of heated steam to decompose. Immediately after that, it is preferable to cool the particles to a temperature (preferably 100° C. or less) at which the particles do not coalesce again in the shortest possible time.

By the above means, fine powder having a fine primary particle diameter can be obtained.

A more detailed description will be given.

That is, the present inventors have conducted various studies to suppress coarsening of the fine powder and produce fine powder with less cohesiveness. As a result, not only the TiO ₂ component but also Ti(OR)m
In the case of a composition containing the (OH)n component as an essential component, the crystallization of titanium oxide is suppressed, the particles become finer in particle size, the shape becomes more spherical, and Ti-
The present inventors have found that the OH group is displaced in the direction of increasing the number and reached the present invention.

This cannot be achieved by using rutile type or anatase type titanium oxide or amorphous titanium oxide.

Among them, the TiO ₂ component and Ti used in the present invention
The fine powder of the composition containing the (OR)m(OH)n component as the main component is composed of TiO ₂ component 85 to 99.5% by weight, and Ti(OR)m(OH)n component 0.5 to 15% by weight. Have

That is, when the TiO ₂ component is less than 85%, a large amount of titanium alkoxide and titanium hydroxy component remains, or a system containing a large amount of impurities applies to this, and a sharp particle size distribution is obtained. It is difficult to produce a fine powder having the above, and individual particles are likely to have a non-uniform composition, and the toner containing the fine powder as described above has a broad charge amount distribution when charged with carrier particles. However, it is difficult to achieve uniform development and high transfer rate.

On the other hand, when the TiO ₂ component is more than 99.5% by weight, the fine powder approaches the pure titanium oxide particles as much as possible, the crystal structure is easily taken, and the particles tend to become coarse. With this, it is not easy to obtain the desired good fluidity.

When the content of Ti(OR)m(OH)n is less than 0.5% by weight, the dispersibility of the treated fine powder in the colorant-containing resin particles is extremely reduced, and especially the colorant-containing When they are attached to the surface of the resin particles (when the treated fine powder is added externally), they are likely to be detached from the surface of the colorant-containing resin particles, which easily causes carrier contamination and drum contamination. Especially when the carrier surface is contaminated, the charge amount of the toner is greatly reduced, and the toner is scattered during durability,
Fog and the like deteriorate, and it becomes difficult to secure a constant image density. Furthermore, the Ti(OR)m(OH)n component is 0.5% by weight.
If the amount is smaller, the fine powder tends to be coarse, and it becomes difficult to improve the fluidity of the toner to a target level.

On the other hand, the Ti(OR)m(OH)n component is 1
If the amount is more than 5% by weight, a system in which hydrolysis or thermal decomposition does not proceed to a desired level is applicable to this, and the composition of the fine powder itself becomes widely varied. In this case, it is not easy to generate a toner with a stable tribo distribution that is electrostatically stable. In particular, both the titanium alkoxy component and the titanium hydroxy component have much stronger properties of adsorbing water than the titanium oxide component. Therefore, when the Ti(OR)m(OH)n component is more than 15% by weight, the high temperature and high humidity are particularly high. Under the environment, the charge amount is likely to be insufficient, and toner scattering, fog, etc. during durability are likely to occur.

Further, the Ti(OR)m(OH)n component is 1
If the amount of the fine powder is more than 5% by weight, the cleaning property may be deteriorated and a defective cleaning mark may be generated on the image. This is because the surface of the photoreceptor is fine powder (especially Ti
(Fine powder containing more (OR)m(OH)n component)
It is presumed that the toner is largely contaminated with the toner, and the releasability of the toner from the photoconductor is greatly reduced.

Therefore, in the present invention, the treated fine powder contains 0.5 to 15% by weight of the Ti(OR)m(OH)n component,
Preferably 1.0 to 12% by weight, more preferably 1.5.
Those containing 10 to 10% by weight are preferable.

TiO ₂ component and Ti(OR)m(OH)n
The composition ratio with the components is determined by the following procedure.

First, the fine powder is left to stand in a vacuum dryer at 60° C. for 3 days and dried under reduced pressure to determine the water content.

Next, an elemental analyzer EA- manufactured by Carlo Erba Co.
At 1108, the amount of C and the amount of H are calculated, and from these values, the composition ratio of the TiO ₂ component and the Ti(OR)m(OH)n component is calculated.

Compounds other than TiO ₂ are Ti(O
It was confirmed by FT-IR analysis that the compound represented by R)m(OH)n (m+n=4) was obtained.
The components other than the above two compounds are trace amounts and can be ignored.

In addition to titanium alkoxides such as titanium tetramethoxide, titanium tetraethoxide, titanium tetrapropoxide, titanium tetrabutoxide and diethoxytitanium oxide, as raw materials for the fine powder used in the present invention,
Tetrahalogenated titanium compounds such as titanium tetrachloride and titanium tetrabromide, and volatile titanium compounds such as trihalogenated monoalkoxy titanium, dihalogenated dialkoxy titanium, and monohalogenated trialkoxy titanium can also be used.

When vaporizing or atomizing the volatile titanium compound, it is preferable to dilute the volatile titanium compound with a diluent gas to a ratio of 0.1 to 10% by weight. This diluting gas serves as a carrier gas for introducing the vaporized volatile titanium compound into a decomposition furnace for decomposing.

Here, as the diluent gas, argon gas,
An inert gas such as helium gas or nitrogen gas, water vapor or oxygen is used. Particularly, it is preferable to use helium gas and/or nitrogen gas. Further, if necessary, a dispersion aid, a surface modifier and the like may be added.

In the present invention, since the volatile titanium compound is decomposed after being vaporized or atomized, an oxygen-containing gas is necessary except that an oxygen-containing compound such as alkoxide is used.

The decomposition temperature is preferably 600° C. or lower, more preferably 200 to 400° C., and particularly preferably 250 to 350° C. At a temperature below 200°C, it is difficult to obtain a sufficient decomposition rate, while at a temperature above 600°C, it is difficult to obtain fine fine powder.

Further, in the present invention, it is preferable to rapidly cool to a temperature at which they do not coalesce immediately after decomposition so that the produced fine powders do not coalesce again in the gas phase. The rapid cooling prevents coalescence of the fine powder, and the obtained fine powder can be collected and collected in the state of primary particles.

Next, the surface treatment which is another feature of the present invention will be described.

The present invention is also characterized in that the surface of the fine powder is surface-treated with a silane organic compound in order to adjust the charging characteristics and improve the stability under high humidity.

In particular, as described above, after the fine powder which becomes the core is formed by the vapor phase method, immediately the fine powder is mixed with the vaporized or atomized silane-based organic compound, and then the surface treatment is carried out in the vapor phase. Preferably.

The TiO ₂ component and Ti proposed by the present inventors
The fine powder of the composition containing the (OR)m(OH)n component as the main component has much higher surface activity than that of pure titanium oxide, that is, Ti-OH capable of reacting with a silane-based organic compound. Since it contains more groups, it is advantageous for the reaction, and can be uniformly treated with a small amount of a treating agent, and the degree of hydrophobicity can be increased. Especially when the surface treatment is performed in the gas phase, unlike the conventional wet treatment, the surface treatment can be performed without taking steps such as filtration, drying and crushing, so that the characteristics of the fine powder before treatment are not impaired and uniform. Moreover, it becomes possible to sufficiently perform the surface treatment.

TiO ₂ component and Ti(OR)m(OH)n
The treatment amount and treatment time of the silane-based organic compound with respect to the fine powder of the composition containing as a main component are not particularly limited, but the treated fine powder after treatment has a Si amount of 1.5 to 16 in terms of SiO _2. % By weight, preferably 2.5-14% by weight
Therefore, it is preferable that the surface of the fine powder is treated with a silane-based organic compound.

The amount of Si in terms of SiO _{2 of the} treated fine powder was 1.
When it is less than 5% by weight, it means that the treatment is not sufficient, or the treatment has failed for some reason,
In this case, there is a tendency that the charge amount is insufficient, the density is increased particularly under high temperature and high humidity, toner scattering at endurance, fog and the like are deteriorated. Further, when the Si amount in terms of SiO ₂ exceeds 16% by weight, this corresponds to the case where the amount of the silane-based organic compound treated is extremely large, and this corresponds to a fine powder having a small primary particle size and a low cohesiveness. Is not easy to produce, resulting in treated fine powder with many agglomerates. With this, it is not easy to impart good fluidity to the toner. Due to the treatment agent that has not sufficiently reacted with the surface of the fine powder of the base material and the like, a toner image with a large amount of fog and a rough surface is easily generated. Further, this causes a new problem of carrier contamination.

As described above, the fine powder of the composition of the present invention containing the TiO ₂ component and Ti(OR)m(OH)n as the main components is much finer than the conventional titanium oxide. It has a large amount of Ti-OH groups in it, and therefore has a high surface activity, and is advantageous for the reaction with a silane-based organic compound. It can uniformly treat the fine powder surface with a small amount of a treating agent to enhance the degree of hydrophobicity. ..

In addition, when the treatment is carried out in the gas phase, it is possible to increase the Si content in terms of SiO ₂ without forming secondary aggregates. This is something that other processing methods, such as wet processing, could not do. In other words, by simply increasing the amount of the treating agent added to increase the SiO ₂ equivalent Si amount by the usual wet treatment method, the SiO ₂ equivalent Si amount itself can be increased, but the particles of the fine powder are inevitably separated from each other. The BET specific surface area is low and the apparent primary particle size tends to be large as compared with before the treatment.

On the other hand, in the case of the vapor phase treatment method, the amount of Si in terms of SiO ₂ can be increased with almost no change in the value of BET specific surface area before and after the treatment and with the primary particle diameter of the base material being maintained.

In the present invention, the fluorescent X-ray spectroscopic analysis method is used to measure the Si content in terms of SiO ₂ .

The silane-based organic compound used in the present invention does not decompose thermally at the reaction treatment temperature, has volatility, and has both a hydrophobic group and a highly reactive bonding group. It is preferable to use an alkoxysilane represented by the following general formula.

RmSiYn [In the formula, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents a hydrocarbon group such as an alkyl group, a vinyl group, a glycidoxy group and a methacryl group, and n is 1 to 1]. An integer of 3] For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, Dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyritrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-
Octadecyl trimethoxysilane etc. can be mentioned.

More preferably, the formula

[0054]

[Outer 1] An alkylalkoxysilane compound represented by the formula [wherein a represents an integer of 4 to 12 and b represents an integer of 1 to 3] is preferable.

When a in the general formula is smaller than 4, the treatment is easy, but good hydrophobicity is difficult to obtain.
If a is greater than 13, the hydrophobicity will be sufficient, but the coalescence of the fine powders will increase and the fluidity imparting ability will tend to decrease.

If b is larger than 3, the reactivity is lowered and it is difficult to obtain good hydrophobicity.

Therefore, in the present invention, a is preferably 4 to 12, more preferably 4 to 8, and b is preferably 1 to 3, more preferably 1 to 2.

Further, the treated fine powder in the present invention has an average particle size of preferably 0.005 to 5 from the viewpoint of imparting fluidity.
0.1 μm, and more preferably 0.01 to 0.05 μm.

When the average particle diameter is larger than 0.1 μm, the fluidity is lowered and the toner is apt to be non-uniformly charged, resulting in toner scattering, fog and the like, which makes it difficult to form a high quality toner image. .. The average particle size is 0.0
If it is less than 05 μm, the treated fine powder is likely to be embedded on the surface of the colorant-containing resin particles, the toner is likely to deteriorate quickly, and the durability is likely to be lowered. This tendency is more remarkable than when it is applied to a sharp melt color toner.

The particle size of the treated fine powder in the present invention is measured by a transmission electron microscope.

[0061]

EXAMPLES Examples of the present invention will be described below.
[%] and [parts] all indicate [% by weight] and [parts by weight].

Synthesis Example 1 Titanium tetraisopropoxide was used as a raw material. The raw materials were completely vaporized by feeding the raw materials little by little with a chemical pump to an evaporator heated to 200° C. using nitrogen gas as a carrier gas. On the other hand, using a chemical pump, together with nitrogen as a carrier gas, water is sent to an evaporator to be vaporized and further heated, and then sent to the reactor together with the vaporized raw material at a temperature of 280.
Titanium oxide-based fine powder-A was obtained by heating and decomposing at 0°C and then immediately quenching.

The composition was as shown in Table 1.

Synthesis Example 2 Instead of titanium tetraisopropoxide, titanium tetranormal propoxide was used, and the temperature of the evaporator was 220° C.
Then, titanium oxide fine powder-B was obtained in the same manner as in Synthesis Example 1 except that the temperature of the reactor was set to 300°C.

Synthetic Example 3 A titanium oxide fine powder-C was obtained in substantially the same manner as in Synthetic Example 1, except that the thermal decomposition temperature was 650°C.

Synthetic Example 4 Titanium oxide fine powder-D was obtained in the same manner as in Synthetic Example 1, except that rapid decomposition was not carried out after thermal decomposition.

Synthesis Example 5 Synthesis Example 1 except that the temperature of the thermal decomposition was set to 200° C. and the amount of water fed into the reactor was reduced in Synthesis Example 1.
Titanium oxide fine powder-E was obtained in the same manner as described above.

Synthetic Example 6 In the same manner as in Synthetic Example 1, except that the temperature of thermal decomposition was lowered from 280° C. to 170° C. and the amount of titanium tetraisopropoxide as a raw material fed in was increased, the titanium oxide fine powder was prepared in substantially the same manner. Body-F was obtained.

Comparative Synthesis Example 1 Titanium tetrachloride was decomposed by heating in a gas phase at 800° C. to obtain titanium oxide fine powder-G.

Comparative Synthetic Example 2 Titanium oxide fine powder-H was obtained by neutralizing in an aqueous solution of titanium sulfate, and then producing a precipitate by a sulfuric acid method of firing.

The data of each fine powder are shown in Table 1.

[0072]

[Table 1]

Example 1 Titanium tetraisopropoxide was used as a raw material. Titanium tetraisopropoxide was fed little by little by a chemical pump into an evaporator heated to 200° C. using nitrogen gas as a carrier gas to completely vaporize titanium tetraisopropoxide. On the other hand, using a chemical pump, water was sent to the evaporator together with nitrogen gas as a carrier gas to be vaporized and further heated, and then the vaporized titanium tetraisopropoxide was also heated at 280° C. in the reactor. After thermal decomposition, using nitrogen gas as a carrier gas, isobutyltrimethoxysilane, which is a surface treatment agent, was sent to the evaporator by a chemical pump and completely vaporized, and the nitrogen flow containing the fine powder and heated steam synthesized earlier was used. Then, the mixture was reacted at 280° C., subjected to a hydrophobization treatment, and rapidly cooled at the same time to collect hydrophobic titanium oxide fine powder-I whose surface was modified with isobutyltrimethoxysilane. Its composition is shown in Table 2.

Example 2 A surface-modified hydrophobic titanium oxide fine powder-J was obtained in the same manner as in Example 1 except that propyltriethoxysilane was used instead of isobutyltrimethoxysilane.

Example 3 Instead of titanium tetraisopropoxide, titanium tetranormal propoxide was used and the temperature of the evaporator was set to 220.
C., hydrophobic titanium oxide fine powder-K surface-modified in the same manner as in Example 1 except that the temperature of the reactor was 300.degree.
Got

Comparative Example 1 The titanium oxide fine powder-A obtained in Synthesis Example 1 was mixed with stirring in an aqueous system so that the coupling agent (normal butyltrimethoxysilane) was 20% by weight based on the fine powder. And mixed so that the particles do not coalesce, dried and crushed to obtain a surface-modified hydrophobic fine titanium oxide powder-L.

Example 4 Hydrophobic titanium oxide fine powder surface-modified in substantially the same manner as in Example 1 except that the feed amount of titanium tetrapropoxide as a raw material was increased and pyrolysis was not carried out, followed by rapid cooling. -M was obtained.

[0078] TiO ₂ component was subjected to a fine powder also synthesized composition analysis only did not surface modification in the same manner as 9
The content was 0.2% by weight, and the Ti(OR)m(OH)n component was 7.2% by weight.

Comparative Example 2 The titanium oxide fine powder-G obtained in Comparative Synthesis Example 1 was hydrophobized with octyltrimethoxysilane by a wet method to obtain a hydrophobic titanium oxide fine powder-N.

Comparative Example 3 The titanium oxide fine powder-H obtained in Comparative Synthesis Example 2 was hydrophobized with octyltrimethoxysilane by a wet method to obtain a hydrophobic titanium oxide fine powder-O.

Table 2 shows the data of each hydrophobic fine powder.

[0082]

[Table 2]

Experimental Example 1 Polyester resin obtained by condensing propoxylated bisphenol and fumaric acid 100 parts Phthalocyanine pigment 4 parts Di-tert-butylsalicylic acid chromium complex salt 4 parts

The above materials are sufficiently premixed by a Henschel mixer, melt-kneaded by a twin-screw extruder, cooled, roughly crushed to about 1 to 2 mm by a hammer mill, and then finely crushed by an air jet system. Finely crushed with.
Further, the finely pulverized product obtained is classified to have a weight average particle diameter of about 8 μm.
Colorant-containing resin particles were obtained.

100 parts by weight of the colorant-containing resin particles and 0.5 parts by weight of the hydrophobized fine powder-I of Example 1 were mixed with a Henschel mixer to obtain a cyan toner. This cyan toner had a weight average diameter of 8μ. When the treated fine powder on the colorant-containing resin particles was observed by SEM, it was confirmed that the fine particles were uniformly attached to the surface of the colorant-containing resin particles in the state of almost primary particles.

A Cu-Zn-Fe ferrite carrier having an average particle size of 50 μm was coated with 0.5% of a copolymer of 50% by weight of styrene, 20% by weight of methyl methacrylate and 30% by weight of 2-ethylhexyl acrylate. 95 parts of ferrite carrier and 5 parts of cyan toner were mixed to obtain a two-component developer.

Using this developer, the development contrast was set to 300 V with a commercially available plain paper color copying machine (color laser copier 550, made by Canon), and the temperature was 23° C./
Image formation was performed under a humidity of 65% RH. The obtained image was subjected to reflection density measurement using a Macbeth RD918 type using an SPI filter (the same applies to the subsequent image density measurement method).
The toner image density was as high as 1.52, and it was clear without fog. After that, 10,000 more copies were made, and the density fluctuation during that time was as small as 0.08, and fog and sharpness similar to those at the initial stage were obtained. Even under low temperature and low humidity (temperature 20°C, humidity 10%RH), when the development contrast was set to 300V and images were printed, the image density was as high as 1.44, which is also effective for controlling the charge amount under low humidity. was there.

When a cyan toner image was transferred onto an OHP film and fixed, it was transmitted through an overhead projector, and a clear cyan image was projected on the screen.

Even under high temperature and high humidity (temperature 30° C./humidity 80%
(RH) Similarly, when the development contrast was set to 300 V and image formation was performed, the image density was 1.54, and a very stable and good image was obtained.

23° C./60% RH, 20° C./10%
No abnormality was observed in the initial images after being left for 1 month in each of RH and 30° C./80% RH environments.

The image characteristics are shown in Table 3 (the same applies hereinafter).

Experimental Examples 2 and 3 A toner and a two-component developer were prepared in the same manner as in Experimental Example 1 except that the surface-modified treated fine powder-J and treated fine powder-K were used. When tested in the same manner as in 1, good results were obtained.

Comparative Experimental Example 1 A toner and a two-component developer were prepared in the same manner as in Experimental Example 1 except that the surface-modified treated fine powder-L was used, and tested in the same manner as in Experimental Example 1. ..

By surface treatment, high temperature and high humidity (temperature 30° C.,
The chargeability is stable at a humidity of 80% RH, and the image density is about 1.
It remained stable at 5. Under low temperature and low humidity environment (temperature 20℃,
At a humidity of 10% RH, the image quality of the toner image deteriorated as compared with Experimental Example 1 as the durability test progressed. It is considered that this is because the fluidity of the toner is lower than in Experimental Example 1, and the transferability is reduced.

When the surface of the toner was observed with an SEM, it was confirmed that some of the treated fine powders were agglomerated and adhered to the surface. The proportion of treated fine powder was small.

Experimental Example 4 A toner and a two-component developer were prepared in the same manner as in Experimental Example 1 except that the surface-modified treated fine powder-M was used, and tested in the same manner as in Experimental Example 1.

A toner image was obtained in which the fine line reproducibility and the halftone reproducibility were slightly inferior to those of Experimental Example 1, but the mixing ratio with the colorant-containing resin particles was 0.5 to 1.0 parts by weight. The image quality was improved by increasing the amount.

Comparative Experimental Example 2 A test was conducted in the same manner as in Experimental Example 1 except that hydrophobic titanium oxide fine powder-O was used.

The image quality deteriorated under low temperature and low humidity and after many sheets were used.

Comparative Experimental Example 3 A test was conducted in the same manner as in Experimental Example 1 except that the hydrophobic titanium oxide fine powder-P was used.

Image quality deteriorated under low temperature and low humidity and after many sheets were used.

Table 3 shows the results of the experimental example and the comparative experimental example.

[0103]

[Table 3]

[0104]

The hydrophobic titanium oxide-based fine powder of the present invention is
It is useful as an external additive for electrophotographic toner.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-19528 (JP, A) JP-A-5-204183 (JP, A) JP-A-60-186418 (JP, A) JP-A-1- 145306 (JP, A) JP-A-1-145307 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01G 23/04 G03G 9/08 374

Claims (5)

(57) [Claims] 1. A TiO ₂ component containing 85 to 99.5% by weight.
Is _{Yes, Ti (OR) m (OH} ) n component [wherein, R represents a hydrocarbon group, m and n represents an integer of 0 to 4, m + n
Is a is] is in the gas phase the titanium oxide fine powder formed in the composition that are contained 0.5 to 15 wt% 4, vaporization of
Formula RmSiYn [wherein R represents an alkoxy group, m is an integer of 1 to 3]
Y is an alkyl group, a vinyl group, a glycidoxy group and
Represents a hydrocarbon group selected from a methacryl group, and n is 1
To be treated with the alkoxysilane compound represented by the ~ 3 represents an integer of]
The obtained Si amount in terms of SiO ₂ is 1.5 to 16% by weight.
A hydrophobic titanium oxide-based fine powder, characterized in that it is made of a hydrophobic fine powder. Wherein said alkoxysilane compound has the following formula _{C a H 2a + 1 -Si- (} O b CH 2a + 1) 3 [wherein, a is an integer of 4 to 12, b is 1 to 3 An integer
An alkyl alkoxy silane compound represented by the indicating]
The hydrophobic titanium oxide-based fine powder according to claim 1,
body. 3. The Ti(OR) _m (OH) _n The ingredients are 1.
The content of 0 to 12% by weight according to claim 1 or 2.
Hydrophobic titanium oxide fine powder. Wherein said titanium oxide-based fine powder has an average primary particle size of 0.005~0.1μm claims 1 to 3 Neu
The hydrophobic titanium oxide-based fine powder according to any one of the above. Wherein said titanium oxide-based fine powder, hydrophobic titanium oxide fine powder according average primary particle diameter in claim 4 is 0.01 to 0.05 [mu] m.