JP2000034122A - Ultrafine particle titanium dioxide, its production and its application - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize antistatic characteristics such as frictional electricity, etc., and to improve environmental dependence, fluidity and caking resistance by including a specific amount of needle rutile titanium dioxide, forming an indeterminate particle structure and specifying a specific surface area. SOLUTION: This ultrafine particle titanium dioxide for an additive comprises 1-6 wt.% needle rutile titanium dioxide to form an indeterminate particle structure of agglomerated primary particles having 0.005-0.01 μm particle diameters and to give 150-210 m2/g specific surface area and is useful for providing a toner having excellent characteristics. The ultrafine particles titanium dioxide has its particle surface coated with a layer containing Al, Si, Ti, Zr, Sn, etc., to adjust an amount of static electrification and is further treated with a silane coupling agent to improve dispersibility. The rutile type titanium dioxide is obtained by adding 2-10 wt.% colloidal sol seed of a rutile crystal structure to a hydrolyzate mother liquor, hydrolyzing it, deflocculating obtained metatitanic acid, washing, drying and baking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrafine titanium oxide useful as an external additive of a toner for developing an electrostatic latent image for forming a copied image of a copying machine, a printer, and the like. The present invention relates to an ultrafine titanium oxide which is optimal for supplying a toner which can obtain a copy image with high sharpness and which has a small environmental fluctuation in performance, a method for producing the same, and a toner containing the same.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand in the market for higher definition and higher image quality of electrostatic images obtained by copying machines and printers. To reduce the particle size of toner or to use polyester resin as binder resin. Attempts have been made to achieve higher image quality by using the same. However, when the particle size of the toner is reduced, the charge amount of the toner increases, the adhesion between the toners increases, and the fluidity decreases. In addition, when a polyester resin is used as the binder resin, it is easily affected by temperature and humidity, and the charge amount becomes too high at low humidity, and the charge amount becomes insufficient at high humidity. There is a problem that it is difficult to obtain a toner having a charged amount.

On the other hand, conventionally, silica, titanium oxide, or the like has been externally added to a toner used for electrostatic latent image development for the purpose of imparting fluidity and improving cleaning properties. Surface treatment has been performed. For example, JP-A-62-113158 and JP-A-64-6
No. 2667 proposes a technique of externally adding hydrophobic silica and titanium oxide, respectively.

From such a viewpoint, Japanese Patent Application Laid-Open No.
No. 88633 proposes to use a hydrophobic anatase-type titanium oxide having a light transmittance of 40% or more for a light wavelength of 400 nm and treated with a silane coupling agent. This hydrophobic anatase type titanium oxide is obtained by treating anatase type titanium oxide fired at a relatively low temperature of 300 to 500 ° C. with a silane coupling agent so as not to sinter metatitanic acid. Also, Japanese Patent Application Laid-Open
No. 3177 discloses that a titanium compound obtained by reacting TiO (OH) ₂ with a silane coupling agent is used. This titanium compound is obtained by subjecting metatitanic acid to a surface treatment while hydrolyzing a silane coupling agent in an aqueous medium.

When anatase type titanium oxide and a titanium compound obtained by these methods are externally added to a toner,
It has the characteristics that the adhesion and dispersibility to the toner are extremely good, the fluidity comparable to that of silica is obtained, the fine particles adhering to the toner are hard to separate, and the spent of the carrier is prevented.

However, the toner to which anatase-type titanium oxide and a titanium compound obtained by these methods are externally added does not adhere to the toner due to collision between the carrier and the toner due to agitation or friction between the toner and the blade or sleeve. However, there is a problem that the toner is gradually buried in the toner and the charging becomes unstable.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and shows stable charging characteristics without lowering triboelectric charging characteristics, and has environmental dependency, fluidity and anti-caking properties. It is an object of the present invention to provide ultrafine titanium oxide for external addition for obtaining excellent toner.

The present inventors first investigated the cause of the problem of the toner to which the above-mentioned anatase-type titanium oxide and titanium compound were externally added. As a result, the above-mentioned anatase-type titanium oxide and titanium compound were flaky. It has been found that the flaky shape causes the problems described above.

It is well known that a typical method of producing titanium oxide by a sulfuric acid method is a Mecklenburg method in which a colloidal sol separately prepared as a seed for hydrolysis is added to a hydrolysis mother liquor for hydrolysis. However, when producing anatase-type titanium oxide, anatase-type forming seeds, and when producing rutile-type titanium oxide, hydrolysis is performed by adding a seed having a rutile crystal structure that promotes rutile transition, Metatitanic acid is generated and baked to produce titanium oxides with different crystal forms.

The present inventors have paid attention to metatitanic acid obtained by the Mecklenburg method and made various studies to obtain metatitanic acid which does not exhibit a flaky shape. As a result, when the anatase type forming seed was added and the hydrolysis was performed, the calcined anatase type titanium oxide was 0.2 to 0.8 μm.
On the other hand, when a seed having a rutile crystal structure is added in an amount of more than 0.5 to 1.5% by weight, which is a usual addition amount, and the hydrolysis is performed, the flake shape is reduced. It does not form, it becomes an irregular shape, and the calcined titanium oxide shows a particle structure with rutile type titanium oxide as the core and anatase type titanium oxide growing around it, and needle-like rutile type titanium oxide is formed. Contained, 0.005
The present invention was found to have a structure in which fine particles having a size of ~ 0.01 µm were irregularly assembled, and the present invention was completed.

[0011]

The ultrafine titanium oxide of the present invention contains acicular rutile type titanium oxide and has a particle size of 0.005 to 0.01 μm.
m is a titanium oxide having an irregular particle structure in which primary particles are aggregated, and has a specific surface area of 150 to 210 m ² / g.
It is characterized by being.

The particle size is less than 0.005 μm and the specific surface area is 2
If it exceeds 10 m ² / g, dispersion becomes poor, which is not preferable. When the particle size exceeds 0.01 μm and the specific surface area is less than 100 m ² / g, the shape becomes flaky, which is not preferable.

The content of the rutile type titanium oxide is 1 to 6
% By weight. When the content of the rutile-type titanium oxide is less than 1% by weight, the shape becomes flaky, which is not preferable. On the other hand, when the content exceeds 6% by weight, the specific surface area becomes large and the dispersion becomes poor. Not preferred.

The surface of the ultrafine titanium oxide particles may be coated with a layer containing one or more of aluminum, silicon, titanium, zirconium and tin.

Furthermore, it is possible to form an uppermost layer which has been treated with a silane coupling agent. That is, the particle surface of ultrafine titanium oxide is treated with a silane coupling agent, or the ultrafine titanium oxide is first coated with a layer containing the above element as a lower layer, and then a silane coupling agent is formed thereon as an upper layer. It can also be processed.

The ultrafine titanium oxide of the present invention contains acicular rutile-type titanium oxide and has a content of 0.005 to 0.01 μm.
Since it is an amorphous titanium oxide having a particle structure in which fine particles of m are aggregated, when used as an external additive for toner, it shows stable charging characteristics without reducing triboelectric charging, and is environmentally dependent and stable over time. , A toner having excellent fluidity and anti-caking properties can be obtained.

Also, the surface of the ultrafine titanium oxide particles is
By covering with a layer containing one or more of aluminum, silicon, titanium, zirconium and tin, the charge amount when the toner is used can be adjusted.

The surface of the ultrafine titanium oxide particles is
By treating with a silane coupling agent, a toner having an increased degree of hydrophobicity and improved dispersibility, and having improved environmental dependence and fluidity can be obtained.

The surface of the ultrafine titanium oxide particles is
The lower layer is coated with a layer containing one or more elements of aluminum, silicon, titanium, zirconium and tin, and the upper layer is treated with a silane coupling agent, so that the charge amount is adjusted, and environment-dependent. A toner having improved properties and fluidity can be obtained.

Further, the method for producing ultrafine titanium oxide of the present invention is directed to a method for producing titanium oxide in which a colloidal sol is added to a hydrolysis mother liquor as a seed for hydrolysis and hydrolysis is carried out. Is added, 2 to 10% by weight and hydrolyzed to peptize the metatitanic acid, washed, dried and calcined to form an amorphous titanium oxide containing 1 to 6% by weight of rutile type titanium oxide It is characterized by obtaining.

In the above-mentioned method for producing ultrafine titanium oxide, a seed having a rutile crystal structure for promoting rutile transition added during hydrolysis can be obtained by various methods. The titania sol obtained by sufficiently filtering and washing the orthotitanic acid obtained by neutralization until the sulfate groups are eliminated, and then adding hydrochloric acid and heating is suitable. The amount of the seed added is 2 to 10% by weight, preferably 2 to 6% by weight, based on 100% by weight of titanium oxide in the hydrolysis mother liquor. When the amount of the seed added is less than 2% by weight, the obtained metatitanic acid becomes flaky, which is not preferable. If the amount of the seed exceeds 10% by weight, the particles become extremely small and the dispersion becomes poor.

The peptization of metatitanic acid obtained by hydrolysis is carried out by adding ammonia or caustic to a slurry of agglomerated metatitanic acid, neutralizing, filtering and washing with water to remove the remaining sulfate groups, and then adding hydrochloric acid. , Nitric acid, trichloroacetic acid or other strong basic monobasic acid to adjust the pH to 3 or less, preferably from 0.9 to 2.

The dehydration and calcination of the obtained metatitanic acid is carried out by 3
It can be performed at 00 to 500 ° C. If the temperature is lower than 300 ° C., water of crystallization remains in the crystal structure, which is not preferable. 50
If the temperature exceeds 0 ° C., it is not preferable because sintering of particles occurs and dispersion becomes worse.

The rutile content of the ultrafine titanium oxide is:
It is determined by the amount of seed added and the content of rutile in the seed, and the content of rutile in the seed varies depending on the degree of maturation, so it cannot be determined unconditionally. Since 40 to 60% of rutile-type titanium oxide is generated, the amount of seed can be normally set to 1 to 6% by weight by adjusting the amount of seed added to the above range.

In the process for producing ultrafine titanium oxide according to the present invention, hydrolysis is carried out by using a seed having a rutile crystal structure and adding it in an amount of 0.5 to 1.5% by weight, which is the usual addition amount of rutile seed. Is going. Therefore, when the hydrolysis is performed by adding an anatase-type forming seed, the seed is spherical colloidal particles, so that only aggregates of microcrystals in which primary particles of 60 to 80 ° grow in a flaky shape are obtained. 0.2-0.8μ of calcined anatase type titanium oxide
In contrast, in the case of the present invention, the colloidal particles having a rutile structure added as seeds are needle-like particles, whereas needle-like particles are used in the present invention to grow needles. The particle-like particles hindered the formation of the structure, did not form a flake shape, became an amorphous shape, and the titanium oxide obtained by calcining the titanium oxide contained acicular rutile-type titanium oxide.
Titanium oxide having a structure in which fine particles of 005 to 0.01 μm are irregularly aggregated can be obtained.

Further, in the method for producing ultrafine titanium oxide of the present invention, after the above-mentioned washing treatment, the surface of the particles of metatitanic acid is treated with one or more of aluminum, silicon, titanium, zirconium and tin. Element 1 to
Coating with a layer containing 30% by weight and firing, the particle surface of ultrafine titanium oxide can be coated with the layer. The coating amount of the metal is preferably 1 to 30% by weight, and more preferably 3 to 15% by weight. If the amount is less than 1% by weight, the effect of charge adjustment cannot be obtained, which is not preferable. If it exceeds 30% by weight, the particles will aggregate with each other, which is not preferable.

The titanium oxide obtained by the above calcination is further added to the titanium oxide in an aqueous medium by 15 to 50%.
% By weight of the silane coupling agent is treated with hydrolysis at a pH of 4 or less, then neutralized with alkali, filtered,
By performing washing, drying, and pulverization, the surface of the titanium oxide can be treated with a silane coupling agent.

Dehydrated and calcined rutile-type titanium oxide is added
Before the treatment with the silane coupling agent, the titanium oxide containing 6% by weight needs to be converted into a water slurry, wet-pulverized, and charged / disintegrated / crushed and dispersed. As a wet pulverizer, a bead mill such as a sand grinder, a high-pressure homogenizer, or the like is used.

In the treatment of the silane coupling agent, the water slurry after the wet pulverization is adjusted to pH 4 or less, preferably 0.9 to 2 with hydrochloric acid, and the silane coupling agent is added thereto, and the temperature is 20 to 100 ° C., preferably The coating treatment is performed while heating to 30 to 70 ° C. and performing hydrolysis. Also, pH
When the pH is 4 or less, the hydrolysis of the silane coupling agent is not completed. Therefore, in order to complete the hydrolysis reaction, neutralization is performed using an alkali so as to exceed pH 4 and to 9 and preferably to 5 to 7. By doing so, there is no re-aggregation,
Hydrophobic titanium oxide uniformly coated with the silane coupling agent is obtained.

The treatment amount of the silane coupling agent is 1
It is 5 to 50% by weight, preferably 20 to 30% by weight. When the treatment amount is less than 15% by weight, the hydrophobicity is low, which is not preferable. If it exceeds 50% by weight, agglomeration occurs, the specific surface area decreases, and the dispersion becomes poor. Examples of the silane coupling agent that can be used include a water-soluble silane coupling agent having a chemical structural formula RnSiX4-n (where n is 0 to 3).
R represents an organic group such as a hydrogen atom, an alkyl group and an alkenyl group, and X represents a hydrolyzable group such as a chlorine atom, a methoxy group and an ethoxy group). More than species can be used, chlorosilane,
Although any type of alkoxysilane, silazane and special silylating agent can be used, alkoxysilane is particularly preferable. Examples of the alkoxysilane include vinyltrimethoxysilane, propyltrimethoxysilane, i-butyltrimethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane,
Examples thereof include n-octyltrimethoxysilane, n-dodecyltrimethoxysilane, phenyltrimethoxysilane, and 3-glydoxypropyltrimethoxysilane, and those having 2 to 10 carbon atoms in a hydrocarbon group are particularly preferable. .

After treating the silane coupling agent in an aqueous medium to improve the hydrophobicity and adjust the charge amount,
The silane coupling agent may be treated in the gas phase. In this case, as the silane coupling agent that can be used, fluorosilane, aminosilane, and the like can be used in addition to those described above. When the treatment is performed in the gas phase, the treatment amount is 1 to 30% by weight, preferably 3 to 25% by weight, based on 100% by weight of the obtained fine powder. If the amount is less than 1% by weight, the effect cannot be obtained, which is not preferable. If it exceeds 30% by weight, aggregation is caused and the specific surface area is reduced, which is not preferable.

In the method for producing ultrafine titanium oxide of the present invention, the colloidal sol is added as a seed for hydrolysis to a hydrolysis mother liquor to carry out hydrolysis. After peptizing and washing the metatitanic acid obtained by adding 10 to 10% by weight and performing hydrolysis, the surface of the particles of the metatitanic acid is treated with one of aluminum, silicon, titanium, zirconium and tin or Two or more kinds are coated with a layer containing 1 to 30% by weight, and a silane coupling agent of 15 to 50% by weight with respect to titanium oxide is hydrolyzed at pH 4 or less in an aqueous medium, and then treated with alkali. And then filtration, washing, drying, and pulverization can be performed.

The reason why the metal is coated before the silane coupling agent treatment is to improve the affinity with the silane coupling agent and because the expensive silane coupling agent is efficiently coated and economical. is there. Although the metal coating amount and the silane coupling agent treatment amount are the same as described above, particularly when the metal coating amount is less than 1% by weight, it is difficult to obtain an effect for improving the affinity with the silane coupling agent, and 30% by weight. When the ratio is more than 1, coalescence of particles occurs, which is not preferable.

The toner for developing an electrostatic latent image can also be formed by externally adding the above-mentioned ultrafine titanium oxide of the present invention.

As the toner, any one of a magnetic one-component, a non-magnetic one-component and a two-component toner can be used, and known toner components can be arbitrarily used. For example, as the binder resin, polyester, polyurethane, epoxy resin, silicone resin, polyamide, polystyrene, styrene acrylic resin, methacrylic resin, a derivative thereof, or a mixture thereof can be used. As the coloring agent, pigments such as magnetite and carbon black, phthalocyanine copper-based cyan coloring material, azo-based yellow coloring material, azo-based magenta coloring material,
Known dyes such as quinacridone-based magenta coloring materials can be used. Further, a charge adjusting agent, an anti-offset agent and the like may be contained.

The amount of the hydrophobic titanium oxide obtained in the present invention added to the toner is 0.1 to 3% by weight, preferably 0.2 to 3% by weight.
~ 2% by weight. If the amount is less than 0.1% by weight, the fluidity of the toner cannot be obtained, which is not preferable. If the content exceeds 3% by weight, undesired particles from the toner increase and cause contamination of the photoreceptor and carrier.

In the toner to which the hydrophobic titanium oxide obtained according to the present invention is externally added, if necessary, an external additive such as silica or alumina, a lubricant such as Teflon, zinc stearate or polyvinylidene fluoride, or polyethylene or polypropylene may be used. Other additives such as a fixing aid such as a fixing aid may be added.

[0038]

The present invention will be described in more detail with reference to the following examples. The following examples are provided for illustrative purposes only and do not limit the scope of the invention.

[Preparation of Seed] A titanyl sulfate solution obtained by digesting metatitanic acid subjected to a de-iron treatment with hot concentrated sulfuric acid was added to a 160 g / L sodium carbonate solution at a liquid temperature of 25 ° C.
The titanyl sulfate was stopped when the pH reached 10, and orthotitanic acid was precipitated.

After the precipitate was sufficiently filtered and washed until the sulfate group disappeared, hydrochloric acid was added thereto, and the titanium oxide concentration was 30 g / g.
L and hydrochloric acid concentration were adjusted to 15 g / L. Warm this solution to 8
Aged at 5 ° C. for 30 minutes to prepare a titania sol having a rutile crystal structure.

[0041]

Example 1 Metatitanic acid was synthesized by adding 2.5% by weight of a titania sol having a rutile crystal structure obtained as described above as a seed and performing hydrolysis. After the obtained metatitanic acid was subjected to deiron bleaching treatment, a 4N aqueous sodium hydroxide solution was added to adjust the pH to 9.0, and desulfurization treatment was performed. Thereafter, the mixture was neutralized to pH 5.5 with 6N hydrochloric acid, and filtered and washed with water. Add water to the washed cake and add 10 as titanium oxide
After slurrying at 0 g / L, 6N hydrochloric acid was added to adjust the pH to 1.2.
And peptized. After the peptization was completed, the mixture was neutralized to pH 6.5 with 4N sodium hydroxide, and filtered, washed and dried. The dried metatitanic acid was dehydrated and fired at 300 ° C. to obtain titanium oxide. This titanium oxide was of an irregular shape containing 1% by weight of rutile-type titanium oxide, having a specific surface area of 176 m ² / g, and having a structure in which fine particles having a primary particle size of 0.008 μm were irregularly aggregated.

[0042]

Example 2 Titanium oxide was obtained in the same manner as in Example 1, except that 5% by weight of a titania sol having a rutile crystal structure was used as a seed for hydrolysis. The obtained titanium oxide was irregular, having a structure in which fine particles having a specific surface area of 185 m ² / g and a primary particle diameter of 0.007 μm were irregularly aggregated, containing 3% by weight of rutile type titanium oxide. .

[0043]

Example 3 Titanium oxide was obtained in the same manner as in Example 1 except that a titania sol having a rutile crystal structure was added as a seed and hydrolyzed by adding 8% by weight. The obtained titanium oxide is an irregular one having a structure in which fine particles having a specific surface area of 191 m ² / g and a primary particle diameter of 0.006 μm are irregularly assembled, containing 4.5% by weight of rutile type titanium oxide. there were.

[0044]

Example 4 A titania sol having a rutile crystal structure was added as a seed to add 2.5% by weight and hydrolyzed, and metatitanic acid obtained was subjected to deiron bleaching treatment. Then, a desulfurization treatment was performed. Thereafter, the mixture was neutralized to pH 5.5 with 6N hydrochloric acid, and filtered and washed with water. Water was added to the washed cake to make a slurry of 100 g / L as titanium oxide.
Peptization was performed at 1.2. After the peptization was completed, sodium silicate was added as SiO _{2 at} 2% by weight based on titanium oxide, and sodium aluminate was added as Al ₂ O _{3 at} 6% by weight based on titanium oxide. Thereafter, the mixture was neutralized to pH 6.5 with 4N sodium hydroxide, filtered, washed and dried. The dried metatitanic acid was dehydrated and fired at 300 ° C. to obtain titanium oxide. This titanium oxide was amorphous having a specific surface area of 172 m ² / g and a primary particle size of 0.008 μm, in which fine particles containing 1% by weight of rutile type titanium oxide were irregularly aggregated.

[0045]

Example 5 The titanium oxide obtained in Example 1 was made into a water slurry, wet-pulverized, and 6N hydrochloric acid was added to adjust the pH to 2.
It was adjusted to 0, and 25% of n-butyltrimethoxysilane was added to titanium oxide. After stirring and holding for 30 minutes, a 4N aqueous sodium hydroxide solution was added to neutralize the mixture to pH 6.5, filtered, washed with water, dried at 150 ° C., and then finely pulverized with an air current pulverizer to obtain hydrophobic titanium oxide.

[0046]

Example 6 The titanium oxide obtained in Example 2 was made into a water slurry, wet-pulverized, and 6N hydrochloric acid was added to adjust the pH to 2.
It was adjusted to 0, and 25% of n-butyltrimethoxysilane was added to titanium oxide. After stirring and holding for 30 minutes, a 4N aqueous sodium hydroxide solution was added to neutralize the mixture to pH 6.5, filtered, washed with water, dried at 150 ° C., and then finely pulverized with an air current pulverizer to obtain hydrophobic titanium oxide.

[0047]

Example 7 The titanium oxide obtained in Example 3 was converted into a water slurry, wet-pulverized, and 6N hydrochloric acid was added to adjust the pH to 2.
It was adjusted to 0, and 25% of n-butyltrimethoxysilane was added to titanium oxide. After stirring and holding for 30 minutes, a 4N aqueous sodium hydroxide solution was added to neutralize the mixture to pH 6.5, filtered, washed with water, dried at 150 ° C., and then finely pulverized with an air current pulverizer to obtain hydrophobic titanium oxide.

[0048]

Example 8 The silica and alumina-treated titanium oxide obtained in Example 4 were converted into a water slurry, wet-pulverized, and adjusted to pH 2.0 with 6N hydrochloric acid to oxidize n-butyltrimethoxysilane. 25% was added to titanium. After stirring and holding for 30 minutes, add a 4N aqueous sodium hydroxide solution and adjust the pH.
Neutralized to 6.5, filtered, washed with water, dried at 150 ° C., and then finely pulverized with an air current pulverizer to obtain hydrophobic titanium oxide.

[0049]

Titanium oxide obtained in Example 9 Example 1 was water slurry, after wet grinding, the SiO ₂ 2 wt%, A
6% by weight of l ₂ O ₃ was treated. After treatment, after washing
The pH was adjusted to 3 by adding 6N hydrochloric acid, and 25% of n-butyltrimethoxysilane was added to titanium oxide. After stirring and holding for 30 minutes, add a 4N aqueous sodium hydroxide solution and adjust the pH.
Neutralized to 6.5, filtered, washed with water, dried at 150 ° C., and then finely pulverized with an air current pulverizer to obtain hydrophobic titanium oxide.

[0050]

Example 10 A hydrophobic titanium oxide was obtained in the same manner as in Example 5, except that the treatment amount of n-butyltrimethoxysilane was changed to 17% by weight.

[0051]

Example 11 A hydrophobic titanium oxide was obtained in the same manner as in Example 5, except that the treatment amount of n-butyltrimethoxysilane was changed to 40% by weight.

[0052]

Example 12 A hydrophobic titanium oxide was obtained in the same manner as in Example 7, except that i-butyltrimethoxysilane was used as the silane coupling agent.

[0053]

Example 13 A hydrophobic titanium oxide was obtained in the same manner as in Example 7, except that n-hexyltrimethoxysilane was used as the silane coupling agent.

[0054]

Comparative Example 1 Metatitanic acid obtained by adding 2.5% by weight of anatase type forming seed and performing hydrolysis was treated in the same manner as in Example 1 to obtain titanium oxide. The obtained titanium oxide was a thin plate having a specific surface area of 162 m ² / g and a primary particle size of 0.03 μm.

[0055]

Comparative Example 2 Metatitanic acid obtained by adding 1.2% by weight of a titania sol having a rutile crystal structure as a seed and performing hydrolysis was treated in the same manner as in Example 1 to obtain titanium oxide. The obtained titanium oxide contains 0.5% by weight of rutile type titanium oxide, and has a specific surface area of 150 m ² /
g, having a primary particle size of 0.03 μm.

[0056]

Comparative Example 3 The titanium oxide obtained in Comparative Example 1 was used in Example 5.
The same treatment as described above was performed to obtain a hydrophobic titanium oxide.

[0057]

Comparative Example 4 The titanium oxide obtained in Comparative Example 2 was used in Example 5.
The same treatment as described above was performed to obtain a hydrophobic titanium oxide.

Table 1 shows the properties of the hydrophobic rutile-type titanium oxide fine powders obtained in Examples 5 to 13 and Comparative Examples 3 and 4. These properties were measured in the following manner.

(1) Specific surface area Using an area meter manufactured by Strahlein, Germany,
It was measured by the BET one point method.

(2) Degree of Hydrophobicity An aqueous solution containing 2.5% by weight of methanol is prepared in a test tube, a small amount of fine powder is charged, and then the test tube is shaken up and down to start sedimentation. The methanol concentration at the time was indicated.

[Production of Toner] A polyester resin, carbon black, an anti-offset agent and a charge controlling agent are kneaded.
For 100 parts of 8.0 μm toner pulverized and classified,
2.0% by weight of the hydrophobic rutile-type titanium oxide fine powders obtained in Examples 5 to 13 and Comparative Examples 1 to 4 were added to produce a two-component toner.

The fluidity of each toner was loosened and the apparent density (g / cm ³ ) was measured and evaluated with a powder tester (manufactured by Hosokawa Micron Corporation). Table 1 shows the results.
Are shown together. In Table 1, the higher the loose apparent density, the better the fluidity.

[0063]

[Table 1]

From this result, it can be seen that the toner to which the ultrafine particle titanium oxide of this example was externally added had good fluidity.

[0065]

The ultrafine titanium oxide of the present invention contains acicular rutile type titanium oxide and has a particle size of 0.005 to 0.005.
A titanium oxide having an irregular particle structure in which primary particles of 0.01 μm are aggregated, and the specific surface area of which is 150 to 21.
0 m ² / g, high hydrophobicity and good dispersibility.

Accordingly, the toner to which ultrafine titanium oxide having such properties is externally added has good fluidity,
In addition, the degree of hydrophobicity of the used titanium oxide is high, its shape is irregular, and it contains needle-like rutile-type titanium oxide which is not a conventional flaky shape, so that the triboelectric charging property can be reduced. Further, it is considered that the charging characteristics are stable against changes in temperature and humidity, and the stability over time is also excellent.

Therefore, according to the toner to which the ultrafine titanium oxide is externally added, it is possible to stably obtain a sharply copied image with little environmental fluctuation of charging performance.

The surface of the ultrafine titanium oxide particles is
By being covered with a layer containing one or more of aluminum, silicon, titanium, zirconium and tin, the charge amount when the toner is used can be adjusted.

The surface of the ultrafine titanium oxide particles is
By being treated with the silane coupling agent, the degree of hydrophobicity is increased, the dispersibility is improved, and a toner with improved environmental dependency and fluidity can be obtained.

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[Procedure amendment]

[Submission date] October 23, 1998 (1998.10.
23)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 4

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claim 8

[Correction method] Change

[Correction contents]

Continuing on the front page (72) Inventor Seiji Tsujino Inside of 25 Titan Kogushi Co., Ltd., 1978 Kogushi, Ube-shi, Yamaguchi Prefecture (72) Inventor Takanori Yamazaki Inside of 25 Titan Kogushi Co., Ltd. F term (reference) 2H005 AA08 AB02 CB06 CB07 DA05 EA05 EA07 4G047 CA02 CA05 CA08 CB05 CB09 CC03 CD04 CD07

Claims (8)

[Claims] 1. A titanium oxide containing an acicular rutile-type titanium oxide and having an irregular particle structure in which primary particles having a particle size of 0.005 to 0.01 μm are aggregated, and having a specific surface area of 150 Ultra fine particle titanium oxide having a particle size of up to 210 m ² / g. 2. The content of the rutile type titanium oxide is 1 to 2.
The ultrafine titanium oxide according to claim 1, which is 6% by weight. 3. The method according to claim 1, wherein the surface of the particles is coated with a layer containing one or more of aluminum, silicon, titanium, zirconium and tin. Ultra fine titanium oxide. 4. The method according to claim 1, further comprising a top layer treated with a silane coupling agent.
The ultrafine titanium oxide according to the above. 5. A method for producing titanium oxide in which colloidal sol is added as a seed for hydrolysis to a hydrolysis mother liquor to perform hydrolysis, wherein a seed having a rutile type crystal structure is used in the method.
The metatitanic acid obtained by adding 10% by weight and hydrolyzing is peptized, washed, dried and calcined to obtain an amorphous titanium oxide containing 1 to 6% by weight of rutile type titanium oxide. A method for producing ultrafine titanium oxide, comprising: 6. After the cleaning treatment, the surface of the particles of metatitanic acid is further coated with a layer containing 1 to 30% by weight of one or more of aluminum, silicon, titanium, zirconium and tin. The method for producing ultrafine titanium oxide according to claim 5, further comprising a step of coating. 7. The titanium oxide obtained by calcination is further added to the titanium oxide in an aqueous medium in an amount of 15 to 50%.
% By weight of the silane coupling agent is treated with hydrolysis at a pH of 4 or less, then neutralized with alkali, filtered,
7. The method for producing ultrafine titanium oxide according to claim 5, wherein washing, drying and pulverization are performed. 8. An electrostatic latent image developing toner to which the ultrafine titanium oxide according to claim 1 is externally added.