JP2006195025A - High fluidity titanium oxide, method for manufacturing the same and toner for electrostatic latent image development to which the high fluidity titanium oxide has been added as external additive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high fluidity titanium oxide suitable for obtaining toner for electrostatic latent image development having good fluidity, ensuring small environmental variation of charging performance and stably giving a high sharpness image, and to provide a toner for electrostatic latent image development having the above properties by adding the high fluidity titanium oxide as an external additive. <P>SOLUTION: The high fluidity titanium oxide is obtained by dry-mixing a titanium oxide having an average primary particle diameter of 5-100 nm hydrophobed with an organic substance and silica having an average primary particle diameter of 5-40 nm manufactured by a gas phase method in a silica to titanium oxide ratio of 0.5-20 mass%. The toner for electrostatic latent image development is obtained by adding the high fluidity titanium oxide as an external additive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to high-fluidity titanium oxide, a method for producing the same, and a toner for developing an electrostatic latent image to which the high-fluidity titanium oxide is added as an external additive. Useful as an external additive for toner for developing an electrostatic latent image for forming a copy image such as a printer. By adding the high fluidity titanium oxide as an external additive, the fluidity is good and the It is possible to provide a toner for developing an electrostatic latent image in which an environmental fluctuation of performance is small and a sharp image can be stably obtained.

  In recent years, demands for high definition and high image quality of electrostatic images obtained by copying machines, printers, and the like have increased in the market, and toner particle size has been reduced. However, when the particle size of the toner is reduced, there is a problem in that the charge amount of the toner increases, the adhesion between the toners becomes strong, and the fluidity decreases. In addition, attempts have been made to achieve high image quality by using a polyester resin as a binder resin for the toner. The charge amount becomes too high, the image density decreases, and the image deficiency tends to occur. Conversely, under high humidity, the charge amount is insufficient, the developability deteriorates, and an image with high sharpness is produced. There was a problem that it could not be obtained.

  In addition, inorganic oxide powders such as silica and titanium oxide are externally added to toners conventionally used for developing electrostatic latent images for the purpose of imparting fluidity, imparting chargeability, or improving cleaning properties. Has been proposed (for example, Patent Documents 1 to 6).

  Although some effects can be obtained by externally adding inorganic oxide powder to the toner as in these proposals, silica is excellent in fluidity, but the environmental stability of charging performance is not sufficient. There is a problem, and titanium oxide is excellent in environmental stability of charging performance, but has a problem that fluidity is not sufficient. Therefore, the current situation is that several types of external additives such as silica and titanium oxide are used in combination.

In addition, in recent years, with the increase in color, there are an increasing number of cases where titanium oxide, which is excellent in environmental stability of charging performance, is added to the toner as an external additive, but as described above, because titanium oxide is not sufficiently fluid, The appearance of titanium oxide having fluidity close to silica is awaited.
JP-A-62-213158 JP-A 64-62667 JP 2000-128534 A Japanese Patent No. 3018858 Japanese Patent No. 3038912 Japanese Patent No. 3168347

  The present invention solves the problems of the prior art as described above, and for developing an electrostatic latent image that has good fluidity, has a small environmental fluctuation in charging performance, and can stably obtain a sharp image. An object of the present invention is to provide a high-fluidity titanium oxide suitable for obtaining a toner, and to provide a toner for developing an electrostatic latent image having the above characteristics by adding the high-fluidity titanium oxide as an external additive. And

  As a result of repeating various studies to solve the above problems, the present inventor hydrophobized titanium oxide having a specific particle diameter with an organic substance, and the specific particles produced by the vapor phase method on the hydrophobized titanium oxide. By subjecting the silica having a diameter to a dry mixing treatment at a ratio of 0.5 to 20% by mass of silica with respect to titanium oxide (that is, 0.5 to 20 parts by mass of silica with respect to 100 parts by mass of titanium oxide), When used as an external additive for toner for electrostatic latent image development, high fluidity can provide a toner for electrostatic latent image development that has good fluidity, little environmental variation in charging performance, and high sharpness. The present invention was completed based on the finding that a soluble titanium oxide was obtained.

  That is, the present invention relates to titanium oxide having an average primary particle diameter of 5 to 100 nm hydrophobized with an organic substance, silica having an average primary particle diameter of 5 to 40 nm produced by a gas phase method, and silica with respect to titanium oxide. The present invention relates to a high fluidity titanium oxide characterized by having been dry-mixed at a ratio of 0.5 to 20% by mass, a method for producing the high fluidity titanium oxide, and further, its high fluidity oxidation. The present invention relates to a toner for developing an electrostatic latent image, characterized in that titanium is added as an external additive.

ADVANTAGE OF THE INVENTION According to this invention, the high fluidity titanium oxide useful as an external additive of the electrostatic latent image developing toner for forming copy images, such as a copying machine and a printer, can be provided.
Then, by adding the above high fluidity titanium oxide as an external additive, for electrostatic latent image development, which has good fluidity, small environmental fluctuations in charging performance, and can stably obtain a sharp image. Toner can be provided.

  The typical application of the high-fluidity titanium oxide of the present invention is as an external additive for a toner for developing an electrostatic latent image. The high-fluidity is used to externally add the toner for developing an electrostatic latent image. In addition to the agent, it can be used for powder coatings, additives for resins, cosmetics and the like.

  The reason why the high-fluidity titanium oxide of the present invention is high-fluidity as expressed, and the toner for developing an electrostatic latent image to which it is added as an external additive has good fluidity and small environmental fluctuation of charging performance. The reason why the image with high sharpness can be stably provided will be described together with the description of the material constituting the high-fluidity titanium oxide of the present invention in the following “Best Mode for Carrying Out the Invention” section. .

The titanium oxide constituting the high fluidity titanium oxide of the present invention needs to have an average primary particle diameter of 5 to 100 nm, and the obtained high fluidity titanium oxide is added to the toner for electrostatic latent image development. From the viewpoint of use as an agent, it is more preferably 5 to 50 nm. When the average particle diameter of titanium oxide is less than 5 nm, the production itself is difficult. In the present invention, titanium oxide refers to titanium dioxide (TiO ₂ ), and the average primary particle diameter is a sphere equivalent equivalent diameter obtained from a measured BET specific surface area, and the average of silica described in detail later. The primary particle diameter is also a sphere equivalent diameter obtained from the measured BET specific surface area as in the case of titanium oxide.

  In the present invention, the titanium oxide is hydrophobized with an organic substance. The average primary particle size of 0.5 to 100 nm is the average primary particle size of titanium oxide itself. However, the coating formed on the surface of titanium oxide by the hydrophobic treatment with organic matter is very thin and has almost no effect on the particle size of titanium oxide. The particle size of titanium oxide is hydrophobic treatment with organic matter. There is almost no change before and after.

  In the present invention, as described above, the titanium oxide is hydrophobized with an organic substance. This is because the hydrophobizing process reduces environmental fluctuations in charging performance. The organic substance used for the hydrophobization treatment is not particularly limited as long as it exhibits hydrophobicity, but various substances can be used. However, considering the environmental stability of fluidity and charging performance when used as a toner, Alkoxysilanes, silane coupling agents, silazanes, silicone oils, metal stearates, etc. are preferred, especially silicon-containing organic substances such as alkoxysilanes, silane coupling agents, silazanes, silicone oils, etc., especially alkoxysilanes, silane couplings. An agent or the like is preferable. Examples of the alkoxysilane include methyltrimethoxysilane, isobutyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, and trifluoropropyltrimethoxysilane. Examples of the silane coupling agent include vinyltrimethoxysilane. Vinyl silanes such as methoxysilane, epoxy silanes such as 3-glycidoxypropyltrimethoxysilane, methacryloxy silanes such as 3-methacryloxypropyltrimethoxysilane, amino silanes such as 3-aminopropyltriethoxysilane, etc. Is mentioned. Examples of silazane include hexamethyldisilazane, and examples of silicone oil include straight silicone oil such as dimethylpolysiloxane and methylhydrogenpolysiloxane, amino-modified silicone oil, epoxy-modified silicone oil, Examples thereof include modified silicone oils such as fluorine-modified silicone oil. Examples of the metal stearate include aluminum stearate, magnesium stearate, zinc stearate, calcium stearate and the like. These organic substances can be used alone or in combination of two or more.

  As a processing amount with respect to the titanium oxide of the said organic substance, 5-50 mass% (5-50 mass parts of organic substances with respect to 100 mass parts of titanium oxides) is preferable, and 10-30 mass% is more preferable. When the amount treated with an organic substance is less than 5% by mass, the hydrophobicity is not sufficiently developed. Therefore, the fluidity is poor and the environmental stability of the charging performance is poor, and when the amount is more than 50% by mass, There is a tendency that the aggregation of the titanium oxide particles becomes strong and the fluidity is deteriorated.

  As a method for hydrophobizing titanium oxide with the above organic substance, either a dry method or a wet method can be employed, but a wet method is preferable from the viewpoint of uniformity of treatment. There are two types of wet methods: an aqueous method and a non-aqueous method. In the aqueous method, the treatment agent that can be used is limited in view of the solubility of the treatment agent (organic substance for hydrophobization treatment). A non-aqueous treatment with a high degree of freedom in selection is more preferable. Moreover, it is preferable to perform the treatment while applying strong dispersion from the viewpoint of solving the aggregation of titanium oxide and improving the uniformity of the treatment.

  The silica used for constituting the fluid titanium oxide of the present invention is produced by a gas phase method and has an average primary particle size of 5 to 40 nm, more preferably 5 to 30 nm. In the present invention, among the silicas produced by the vapor phase method or the liquid phase method, the silica produced by the vapor phase method is particularly used because the silica produced by the vapor phase method is produced by the liquid phase method. This is because the fluidity is better than that of silica, and the silica produced by the liquid phase method lacks its own fluidity and cannot provide a sufficient fluidity-imparting effect. In the present invention, among silicas produced by the above gas phase method, silica having an average primary particle size of 5 to 40 nm is particularly difficult to produce when the average primary particle size of silica is less than 5 nm. This is because the effect of imparting fluidity is small when it is larger than 40 nm.

The silica used in the present invention is silicon dioxide (SiO ₂ ), and the high fluidity titanium oxide of the present invention has high fluidity as expressed by the fact that this silica is mixed with titanium oxide. Is. And as a mixing amount of this silica, it is necessary to be 0.5-20 mass% with respect to titanium oxide (5-20 mass parts of silica with respect to 100 mass parts of titanium oxide), and 5-15 masses. % Is more preferable. When the amount of silica mixed with titanium oxide is less than 0.5% by mass, a sufficient fluidity-imparting effect cannot be obtained. When the amount exceeds 20% by mass, a fluidity-imparting effect can be obtained, but the charging performance environment. Stability deteriorates and environmental fluctuations in charging performance increase. The silica may have a surface hydrophobized with an organic material or may be untreated.

  In the present invention, the silica is mixed with the hydrophobized titanium oxide in a dry manner, and this is achieved by maintaining the state where the silica particles are gently connected and mixing with titanium oxide. This is because fluidity can be imparted to titanium oxide. For this dry mixing treatment, a general-purpose mixing apparatus such as a Henschel mixer, a Nauter mixer, a kneader, or a V-type blender can be used. The reason for this is not necessarily clear at present, but Henschel mixers, Nauter mixers, kneaders, etc. have a stronger mixing force than V-type blenders, so they tend to cause granulation, coalescence, and aggregation of particles. In the case of using a V-type blender, it is considered that the above-described particle granulation, coalescence, aggregation and the like are less likely to occur.

  In the present invention, the silica is mixed with titanium oxide in a dry manner as described above. Alternatively, there is a method in which silica is mixed in the step of hydrophobizing titanium oxide with an organic substance. However, in this case, sufficient fluidity cannot be obtained. This is thought to be because, in the step of hydrophobizing titanium oxide with an organic substance, a strong dispersion force is applied, so that the state where the loose particles of silica as described above cannot be maintained cannot be maintained. .

  Since the high-fluidity titanium oxide of the present invention is hydrophobized, it has high stability against environmental changes such as temperature and humidity. Therefore, the environmental stability of charging performance is excellent. Further, since silica is mixed, the fluidity is higher than that of conventional titanium oxide, and the effect of improving the fluidity of the toner when added externally to the electrostatic latent image developing toner is great. Therefore, it can be said that the high-fluidity titanium oxide of the present invention is optimal as an external additive for the toner for developing an electrostatic latent image.

  The electrostatic latent image developing toner using the high-fluidity titanium oxide of the present invention as an external additive can be used for any toner such as magnetic one-component toner, non-magnetic one-component toner, and two-component toner. Known components can be arbitrarily used.

  The addition amount of the highly fluid titanium oxide of the present invention to the toner for developing an electrostatic latent image is 0.1 to 3% by mass (0.1 to 3 parts by mass of the highly fluid titanium oxide with respect to 100 parts by mass of the toner resin). Is preferable, and 0.2-2 mass% is especially preferable. When the addition amount of the high fluidity titanium oxide of the present invention is less than 0.1% by mass, the fluidity of the electrostatic latent image developing toner is not sufficiently improved. There is a tendency for free particles to increase.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are described for illustrative purposes only, and the scope of the present invention is not limited thereby.

Example 1
Disperse 1000 g of titanium oxide (MT-150A manufactured by Teika Co., Ltd.) having an average primary particle diameter of 15 nm in 3000 g of toluene and add 16% by mass of isobutyltrimethoxysilane to the titanium oxide, so that the titanium oxide particles do not merge Then, a strong dispersion treatment was performed, followed by drying and crushing to obtain hydrophobic titanium oxide.
Vitamin blender (Irie Trading Co., Ltd. VK-5) is added to the titanium oxide hydrophobized as described above by adding 5% by mass of vapor phase silica (Aerosil # 300) with an average primary particle size of 7 nm. Was mixed for 20 minutes (rotation speed: 44 rpm) to obtain highly fluid titanium oxide. In addition, said vapor phase method silica is the silica manufactured by the vapor phase method.

Example 2
In hydrophobizing titanium oxide, octyltriethoxysilane was used instead of isobutyltrimethoxysilane, and hydrophobized with dimethyldichlorosilane instead of gas phase method silica (# 300 manufactured by Aerosil) having an average primary particle size of 7 μm. High-fluidity titanium oxide was obtained in the same manner as in Example 1 except that 1% by mass of gas phase method silica having an average primary particle size of 12 nm (R974 manufactured by Aerosil Co., Ltd.) was mixed with respect to titanium oxide.

Example 3
In hydrophobizing titanium oxide, aminopropyltriethoxysilane and octyltriethoxysilane were used in an amount of 8% by mass in place of isobutyltrimethoxysilane, respectively, and the amount of vapor phase silica mixed with titanium oxide was 5% by mass to 10% by mass. Except for the change to%, a highly fluid titanium oxide was obtained in the same manner as in Example 1.

Example 4
In place of titanium oxide having an average primary particle diameter of 15 μm (MT-150A manufactured by Teica) and titanium oxide having an average primary particle diameter of 35 nm (MT-500B manufactured by Teica), the hydrophobization treatment was performed by replacing with isobutyltrimethoxysilane. A highly fluid titanium oxide was obtained in the same manner as in Example 1 except that decyltrimethoxysilane was used and the amount used was changed from 16% by mass to 8% by mass.

Example 5
Instead of gas phase method silica having an average primary particle diameter of 7 μm (# 300 made by Aerosil), gas phase method silica having an average primary particle diameter of 30 nm (# 50 made by Aerosil) was used, and the mixing amount with respect to titanium oxide was 15% by mass. A highly fluid titanium oxide was obtained in the same manner as in Example 1 except that the change was changed to.

Example 6
High-fluidity titanium oxide was obtained in the same manner as in Example 1 except that 3-methacryloxypropyltrimethoxysilane was used in place of isobutyltrimethoxysilane for the hydrophobic treatment of titanium oxide.

Example 7
High-fluidity titanium oxide was obtained in the same manner as in Example 1 except that hexamethyldisilazane was used in place of isobutyltrimethoxysilane for the hydrophobic treatment of titanium oxide.

Example 8
High-fluidity titanium oxide was obtained in the same manner as in Example 1 except that dimethylpolysiloxane was used in place of isobutyltrimethoxysilane for hydrophobizing titanium oxide.

Example 9
A high-fluidity titanium oxide was obtained in the same manner as in Example 1 except that aluminum stearate was used in place of isobutyltrimethoxysilane for the hydrophobic treatment of titanium oxide.

Comparative Example 1
The same procedure as in Example 1 was performed except that silica was not added.

Comparative Example 2
Instead of titanium oxide having an average primary particle size of 15 nm (MT-150A manufactured by Teica), titanium oxide having an average primary particle size of 270 nm (JR manufactured by Teica) was used, and the addition amount of isobutyltrimethoxysilane was changed from 16% by mass to 3% by mass. The procedure was the same as Example 1 except that the percentage was changed to%.

Comparative Example 3
The same procedure as in Example 1 was conducted except that liquid phase silica (average Toso Silica) having an average primary particle size of 80 nm was used instead of vapor phase silica (Aerosil # 300) having an average primary particle size of 7 nm. It was.

Comparative Example 4
This was performed in the same manner as in Example 1 except that the hydrophobization treatment of titanium oxide with isobutyltrimethoxysilane was not performed, and untreated hydrophilic titanium oxide (MT-150A manufactured by Teika) was used as it was.

Comparative Example 5
It was carried out in the same manner as in Example 1 except that mixing of the vapor phase method silica was performed in the hydrophobizing step of titanium oxide.

Comparative Example 6
The same procedure as in Comparative Example 5 was performed except that the mixing amount of the vapor phase method silica was changed from 5 mass% to 10 mass%.

Test example:
The high fluidity titanium oxides of Examples 1 to 9 and the titanium oxides of Comparative Examples 1 to 6 obtained as described above were examined for hydrophobization degree, fluidity, and blow-off charge amount, and using them, pseudo toner And the fluidity thereof was examined. The results are shown in Table 1.

  The method for measuring the degree of hydrophobicity, fluidity, and blow-off charge amount, the method for preparing the pseudo toner, and the method for measuring the fluidity are as follows.

Hydrophobic degree:
Using a powder wettability tester “WET-100P (manufactured by Reska Co.)”, measurement was performed by the following method.
70 ml of pure water is put into a 250 ml tall beaker, and 0.03 g of a measurement sample (measurement sample) is floated on the water surface. While stirring at 300 rpm with a stirrer, methanol is added dropwise at 2.6 ml / min with a metering pump, and the transmittance of this solution is measured. The methanol concentration at the time when the transmittance of the solution is minimized is taken as the measured value of the degree of hydrophobicity.

Liquidity:
It measured by the following method using the granular material fluidity | liquidity measuring apparatus "API Aeroflow (made by TSI Incorporated)."
The measurement sample is weighed into a 60 ml measuring cup and gently placed in a special cylindrical container. The rotational speed of the cylindrical container was adjusted to 1/240 rpm (adjusted so that the rotational speed of the cylindrical container is rotated once in 240 seconds), and measurement was performed for 480 seconds.
The device calculates the time interval and the number of avalanches of powder in a cylindrical container from the intensity of transmitted light, and the measurement results are displayed as the average avalanche time interval (seconds) and the number of avalanches (times). Thus, it can be determined that the sample having a shorter average avalanche time interval and a larger number of avalanche times has better fluidity. Table 1 displays only the number of avalanches.

Blow-off charge amount:
Using a blow-off powder charge measuring device “TB-200 (manufactured by Toshiba Chemical Co.)”, the measurement was performed by the following method.
0.4 g of a measurement sample and 96 g of ferrite are weighed in a polypropylene container, rotated for 15 minutes at a rotation speed of 100 rpm on a biaxial rotor, and 0.05 g of the mixture is weighed on a 500 mesh wire mesh, The blow-off charge amount is measured under the following conditions.
(Nitrogen blow pressure: 0.5 kg / cm ² , blow time: 20 seconds)
In addition, each measurement sample was measured after exposure for 12 hours in three levels of environment (L / L, M / M, H / H).
The temperature / humidity of L / L, M / M, and H / H in Table 1 is as follows.
L / L: 10 ° C, 20% M / M: 20 ° C, 50% H / H: 30 ° C, 80%

Preparation of pseudo toner:
A styrene acrylic toner resin “Hymar SB305 (manufactured by Sanyo Chemical Industries)” was pulverized and classified with a jet airflow type pulverizer to prepare a toner resin. A pseudo-toner was prepared by separately adding 1% by mass of the high fluidity titanium oxides of Examples 1 to 9 and the titanium oxides of Comparative Examples 1 to 6 to 100 parts by mass of the toner resin. The fluidity of the pseudo toner was measured by the same method as the fluidity measurement method such as the high fluidity titanium oxide of Examples 1 to 9 described above.

  Table 1 shows the particle diameters of titanium oxide and silica used in the production of high-fluidity titanium oxide, and the amount of silica mixed with titanium oxide. The particle diameter is related to the average primary particle diameter in terms of space. The% indicating the mixing amount of the silica is expressed by simplifying the mass% in terms of space.

  As shown in Table 1, the high fluidity titanium oxides of Examples 1 to 9 have an avalanche number of 70 or more, which is an index for fluidity evaluation, and the number of avalanches compared to the titanium oxides of Comparative Examples 1 to 6. Many fluidity was excellent. In addition, even when the pseudo toner was prepared, Examples 1 to 9 had more avalanche times and excellent fluidity than Comparative Examples 1 to 6. From this, it is clear that the high fluidity titanium oxides of Examples 1 to 9 contribute to improvement of fluidity when added as an external additive to the electrostatic latent image developing toner. In addition, as shown in Table 1, the high fluidity titanium oxides of Examples 1 to 9 have small differences in L / L, M / M, and H / H in the blow-off charge amount, and there are environmental fluctuations in charging performance. It was small. Therefore, it is considered that the high fluidity titanium oxides of Examples 1 to 9 are useful as external additives for toners for developing electrostatic latent images. The environmental stability of the charging performance by the blow-off charge amount is determined by the value obtained by dividing the difference between the L / L blow-off charge amount value and the H / H blow-off charge amount value by the M / M blow-off charge amount value. The smaller the value is, the smaller the environmental fluctuation of the charging performance is, and it is judged that the environmental stability of the charging performance is excellent.

  Further, as is apparent from the results shown in Table 1, Comparative Example 1 in which silica was not mixed, Comparative Example 2 in which titanium oxide having a large particle size was used, Comparative Example 3 in which silica having a large particle size was used, hydrophobization Comparative Example 4 that was not treated, and Comparative Examples 5 to 6 in which silica was mixed in the hydrophobizing treatment process of titanium oxide were all poor in fluidity, and Comparative Example 1, Comparative Example 2, and Comparative Example No. 4 is estimated to have a large difference in blow-off charge amount and large environmental fluctuations in charging performance.

Claims (8)

Titanium oxide having an average primary particle diameter of 5 to 100 nm hydrophobized with an organic substance is mixed with silica having an average primary particle diameter of 5 to 40 nm produced by a gas phase method, and silica is 0.5 to 20 with respect to titanium oxide. A high-fluidity titanium oxide that is dry-mixed at a rate of mass%. The high-fluidity titanium oxide according to claim 1, wherein the titanium oxide hydrophobized with the organic substance is hydrophobized with an organic substance of 5 to 50% by mass with respect to titanium oxide. The highly fluid titanium oxide according to claim 1 or 2, wherein the organic substance is a silicon-containing organic substance. The high-fluidity titanium oxide according to claim 3, wherein the silicon-containing organic substance is at least one selected from alkoxysilanes, silane coupling agents, silazanes, and silicone oils. The high-fluidity titanium oxide according to any one of claims 1 to 4, wherein the number of avalanches measured under a condition of 1/240 rpm and 480 seconds by a granular material fluidity measurement apparatus is 70 or more. Manufactures titanium oxide with an average primary particle size of 5 to 100 nm in a non-aqueous system using a hydrophobizing process, a process of pulverizing the hydrophobized titanium oxide, and the above-treated titanium oxide by a gas phase method. A process for producing high-fluidity titanium oxide, comprising subjecting silica having an average primary particle diameter of 5 to 40 nm to dry mixing treatment at a ratio of 0.5 to 20% by mass of silica with respect to titanium oxide. 7. The method for producing a highly fluid titanium oxide according to claim 6, wherein the dry mixing treatment is performed by a V-type blender. 6. A toner for developing an electrostatic latent image, wherein the high-fluidity titanium oxide according to claim 1 is added as an external additive.