JP3146679B2 - Hydrophobic metal oxide 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 metal oxide powder used for purposes such as improving powder fluidity.

2. Description of the Related Art A so-called hydrophobic metal oxide powder obtained by hydrophobizing the surface of a metal oxide powder with an organic substance is used for electrophotography, electrostatic recording, and the like.
It is widely used as an agent for improving cleaning properties and the like.
In these applications, the triboelectricity of the metal oxide powder itself with respect to iron or iron oxide as a carrier is one of the important properties, and its hydrophobicity and triboelectricity are simultaneously controlled by various treatment agents. ing. Among these, as a method of reducing negative chargeability or imparting positive chargeability, a method of treating the surface of a powder with an amine-based organic compound is generally used. However, when a low molecular weight compound such as a quaternary ammonium salt is used as the amine-based organic compound, the reproducibility of the obtained charge amount is low because of the low binding property to the surface, and the environment is particularly susceptible to moisture. Problems such as are likely to occur.
On the other hand, when treated with an amino group-substituted silane coupling agent or amino-modified polysiloxane, these treatment agents are chemically or physically firmly fixed to the surface of the metal oxide powder, so that the treatment is effectively performed. Can be obtained. However, these treating agents are relatively expensive, and since there are few commercially available varieties, it is difficult to finely control the charge amount. On the other hand, polyalkyleneimine is an inexpensive and amine-based organic compound having a high molecular weight, and thus is expected as a material for improving the above-mentioned problems of the treating agent. However, when the metal oxide powder is actually treated with the polyalkyleneimine, it is not possible to obtain a high chargeability while maintaining a low affinity for the surface and hydrophobicity.

[0002]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal oxide powder whose charge amount is controlled and which has sufficient hydrophobicity by using inexpensive polyalkylenimine.

[0003]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems and obtain a desired hydrophobic metal oxide powder. By treating the metal oxide powder with the organopolysiloxane simultaneously with the polyalkyleneimine, the charge amount is controlled and a metal oxide powder having sufficient hydrophobicity can be obtained. The goal has been achieved. That is, by reacting the epoxy group in the organopolysiloxane with the amino group in the polyalkyleneimine, the polyalkyleneimine is firmly attached to the surface of the metal oxide powder through the organopolysiloxane having high physical adhesion. The metal oxide powder surface was hydrophobized by the organopolysiloxane at the same time that the compound was effectively combined with positive chargeability, and the above results were obtained. A feature of the present invention is that a metal oxide powder treated with an organopolysiloxane having an epoxy group as a substituent and a polyalkyleneimine has a hydrophobicity of at least 60% as measured by a transmittance method. The metal oxide powder exhibiting a value, the metal oxide powder wherein the metal oxide is silica, alumina or titania, and a hydrophobizing agent other than an organopolysiloxane having an epoxy group as a substituent are used in combination as a treating agent. To provide the above-mentioned metal oxide powder. Hereinafter, the present invention will be described more specifically. The organopolysiloxane having an epoxy group as a substituent used in the present invention means a modified silicone having an appropriate number of epoxy groups in a molecule having reactivity with an amino group in polyalkyleneimine, and a metal oxide. It is not particularly limited except that it has fluidity such that it adheres uniformly to the surface of the material powder.
It is preferable to use one having a viscosity of about 000 cs. Currently commercially available materials include KF manufactured by Shin-Etsu Silicone Co., Ltd.
-101, KF-102, KF-103, KF-10
5, X-22-169AS; SF8411 and SF8413 manufactured by Dow Corning Toray Silicone Co., Ltd. are exemplified. The polyalkyleneimine used in the present invention may be polyethyleneimine, polypropyleneimine or the like generally used for industrial purposes (average molecular weight: about several hundred to hundred thousand), and practically about 30%. Most preferably, an aqueous solution of polyethyleneimine is used. The metal oxide powder used in the present invention can be selected according to the application, but silica, alumina or titania is particularly preferred for applications such as improvement in fluidity. The particle size can also be selected according to the application, but especially when the specific surface area is 5
Those having 0 m ² / g or more are preferable for the above-mentioned applications. The metal oxide may be a composite oxide or a mixture.

[0004] Even if only an organopolysiloxane having an epoxy group as a substituent and a polyalkyleneimine are used, it is possible to impart practically sufficient hydrophobicity to the metal oxide powder. However, to obtain higher hydrophobicity,
For the purpose of saving the amount of the organopolysiloxane having an epoxy group as a substituent, it is desirable to use a hydrophobizing agent other than the organopolysiloxane having an epoxy group as a substituent in combination. As the hydrophobizing agent other than the organopolysiloxane having an epoxy group as a substituent, dimethylpolysiloxane and polymethylhydrosiloxane having no epoxy group are particularly preferable. The amount of the treatment agent suitable for obtaining the hydrophobic metal oxide powder intended for the present invention depends on the type of the metal oxide powder to be treated, the specific surface area and the type of the treatment agent, and is not particularly defined. However, since the use of an excessive amount of polyalkylenimine causes a decrease in hydrophobicity, the polyalkylenimine is usually 20% or less, particularly preferably 12% by weight, not containing water, based on the weight of the metal oxide powder to be treated. % Is desirably used. The amount of the organopolysiloxane having an epoxy group as a substituent depends on the epoxy group pigment, but for the purpose of immobilizing the polyalkyleneimine, 5 to 15 parts by weight of the polyalkylenimine without water is used.
It is desirable to use an amount of 0%, particularly preferably 50-100%.

[0005] The method of measuring the triboelectric charge amount with respect to iron is specified in the literature, for example, "Coloring Material" 55 [9] 630-636.1982. The transmittance method is a method of experimentally determining the hydrophobicity of the treated metal oxide powder, and comprises the following procedure. 1.0 g of the treated metal oxide powder and 100 ml of water are put into a separating funnel for extraction, and vigorously shaken and stirred for 5 minutes. Then, let stand for 1 minute, and draw out a small amount of suspension from the bottom of the separation funnel. The value obtained by expressing the transmittance of this liquid at 550 nm light with the transmittance of pure water as 100% is defined as the hydrophobicity of the metal oxide. The higher the value of the hydrophobization ratio measured in this way, the less the hygroscopicity of the metal oxide powder, the smaller the change in the charge amount of the toner due to humidity, and the more effective it is to prevent agglomeration. High value, but practically more than 60%,
Preferably, it has a value of 70% or more. A conventionally known method is applied to the treatment of the metal oxide powder used in the present invention. That is, while the metal oxide powder to be treated is mechanically sufficiently stirred, an organopolysiloxane having an epoxy group as a substituent, a polyalkyleneimine, and an organopolysiloxane having an epoxy group as a substituent, if necessary. Other hydrophobicizing agents are added dropwise or sprayed. At this time, it is possible to add all the treating agents at the same time, but first add a hydrophobizing agent other than an organopolysiloxane having an epoxy group as a substituent and an organopolysiloxane having an epoxy group as a substituent, and then add The method of adding a polyalkyleneimine is particularly preferable because the reproducibility of the obtained chargeability is high. Further, depending on the viscosity of the polyalkylenimine and the organopolysiloxane to be used, it is also possible to use a solvent such as alcohol, ketone or hydrocarbon as a diluent.
After the addition of the treating agent, the mixture is heated under a nitrogen stream at a temperature in the range of 100 to 250 ° C, particularly preferably in the range of 130 to 170 ° C, to complete the reaction and remove the solvent.
If the above-mentioned dry treatment is difficult depending on the type of the metal oxide powder, the treatment can be carried out under wet conditions using a considerable amount of a solvent.

[0006]

The hydrophobic metal oxide powder according to the present invention is characterized in that an organopolysiloxane having an epoxy group as a substituent is used in combination with a polyalkyleneimine so that the polyalkyleneimine can be more firmly bonded to the metal oxide. As a result of being fixed to the powder surface, it has the following characteristics. Higher positive chargeability is obtained and reproducibility is higher than when no organopolysiloxane having an epoxy group as a substituent is used. In addition, the stability against moisture and the like was improved. Furthermore, the hydrophobic metal oxide powder obtained by the present invention can control the charge amount by changing the amount of the treating agent used, and is expected to be applicable to a wide range of applications.

[0007]

Specific disclosure of the present invention Examples and comparative examples are shown below for the purpose of assisting the understanding of the present invention, but they do not limit the present invention in any way.

Example 1 Heat-dried silica powder ("Aerosil # 130" manufactured by Nippon Aerosil Co., Ltd., specific surface area 13
(0 m ² / g) 10 g was charged into a stainless steel container, and a treating agent having the following composition was sprayed while stirring at room temperature under a nitrogen atmosphere. Treatment agent Polyethyleneimine (30% aqueous solution) 2.00 g Epoxy-modified polysiloxane (Shin-Etsu Chemical Co., Ltd. “KF-101” (2,000 cs)) 0.50 g Dimethyl polysiloxane (Shin-Etsu Chemical Co., Ltd. “KF-96” (50 cs) 1.00 g n-propanol 5.0 ml After spraying was completed, the mixture was further stirred at room temperature for 5 minutes, and then externally heated under a nitrogen stream. The temperature was raised to 150 ° C. over 40 minutes, maintained at this temperature for 60 minutes, and allowed to cool to room temperature. The same operation was repeated to obtain a total of 5 lots of hydrophobic silica powder. The maximum value and the minimum value of the hydrophobicity of these powders by the transmittance method and the triboelectric charge amount with respect to iron were 92%, 82%, 238 μC / g and 198 μC / g, respectively.

[Examples 2 to 10] Table 1 summarizes the results obtained in Example 1 when the composition or type of the treating agent was changed. The hydrophobicity and the triboelectric charge showed the maximum value and the minimum value in 5 lots as in the case of Example 1.

[0010]

[Table 1] Examples 1 to 10 Measurement of amount of treatment agent used Value example Polyethylene ethoxy- modified hydrophobizing agent Hydrophobization rate Coulomb imine ^* a polysiloxane (%) (ΜC / g) (g) (g) (g) (maximum / minimum) (maximum / minimum) 1 20 10 ^* b 10 ^* e 92/82 238/198 2 10 5 ^* b ^{10 * e 95/90 160/} 143 3 5 3 * b 10 * e 97/93 92/65 4 2 1 * b 5 * e 98/93 -52 / -88 5 2 1 * b 10 * e 98/93 -105 / -134 6 10 5 ^* c 10 ^* e 95/91 102/88 7 20 5 ^* c 10 ^* e 89/79 195/174 8 10 3 ^* d 5 ^* e 88/79 140/122 9 20 5 ^* d 10 ^* f 89/75 189/163 10 20 5 ^* b 10 ^* f 94/82 196/177 ^* a: Weight of 30% aqueous solution of polyethyleneimine ^* b: KF-101 made by Shin-Etsu Silicone ^* c: Shin-Etsu Silicone KF-105 ^* d: X-22-169AS ^* e: Shin-Etsu Silicone KF-96 (50cs) ^* f: KF-99, Shin-Etsu Silicone

[Comparative Examples 1 to 3] Table 2 shows the results obtained in Example 1 when no epoxy-modified polysiloxane or polyalkyleneimine was used.

[0012]

[Table 2] Comparative Examples 1-3 Measured amount of treatment agent used Value Comparative Example Polyethylene ethoxy- modified hydrophobizing agent Hydrophobization rate Coulomb imine ^* a polysiloxane (%) (ΜC / g) (g) (g) (g) (maximum / minimum) (maximum / minimum) 1 20 0 10 ^* c 94/86 109/70 2 20 0 15 ^* c 97 / 80 53 / - 5 3 0 5 * b 10 * c 93/88 -560 / -621 * a: weight of polyethyleneimine 30% aqueous solution ^* b: manufactured by Shin-Etsu silicone KF-101 ^* c: manufactured by Shin-Etsu silicone KF -96 (50cs)

Example 11 Heat-dried alumina powder ("Aluminum oxide C" manufactured by Nippon Aerosil Co., Ltd.)
10 g of a specific surface area (90 m ² / g) was charged into a stainless steel container, and a treating agent having the following composition was sprayed while stirring at room temperature under a nitrogen atmosphere. Treatment agent Polyethyleneimine (30% aqueous solution) 2.00 g Epoxy modified polysiloxane (“KF-101” (2,000 cs) manufactured by Shin-Etsu Chemical Co., Ltd.) 0.50 g Dimethyl polysiloxane (“KF-96” (50 cs) manufactured by Shin-Etsu Chemical Co., Ltd.) 1.00 g n-propanol 5.0 ml After spraying was completed, the mixture was further stirred at room temperature for 5 minutes, and then externally heated under a nitrogen stream. The temperature was raised to 150 ° C. over 40 minutes, maintained at this temperature for 60 minutes, and allowed to cool to room temperature. The same operation was repeated to obtain a total of 5 lots of hydrophobic alumina powder. The maximum value and the minimum value of the hydrophobicity of these powders by the transmittance method and the triboelectric charge amount to iron are 85%, 64%, 154 μC / g, and 138 μC / g, respectively.
Met.

Example 12 Heat-dried titania powder (Titanium oxide P2 manufactured by Nippon Aerosil Co., Ltd.)
5 "10 g of a specific surface area of 80 m ² / g) was charged into a stainless steel container, and a treating agent having the following composition was sprayed while stirring at room temperature under a nitrogen atmosphere. Treatment agent Polyethyleneimine (30% aqueous solution) 2.00 g Epoxy-modified polysiloxane (Shin-Etsu Chemical Co., Ltd. “KF-101” (2,000 cs)) 0.50 g Dimethyl polysiloxane (Shin-Etsu Chemical Co., Ltd. “KF-96” (50 cs) 1.00 g acetone 5.0 ml After spraying was completed, the mixture was further stirred at room temperature for 5 minutes, and then externally heated under a nitrogen stream. The temperature was raised to 150 ° C. over 40 minutes, maintained at this temperature for 60 minutes, and allowed to cool to room temperature. The same operation was repeated to obtain a total of 5 lots of hydrophobic titania powder. The maximum value and the minimum value of the hydrophobicity of these powders by the transmittance method and the triboelectric charge amount with respect to iron were 73%, 65%, 105 μC / g and 98 μC / g, respectively.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C09C 3/10 C09C 3/10 G03G 9/08 374 G03G 9/08 374 (56) References JP-A-54-101795 (JP, A) JP-A-3-126601 (JP, A) JP-A-3-163172 (JP, A) JP-A-6-80405 (JP, A) JP-A-2-308173 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) C01B 13/14 B01J 2/00 C01B 33/18 C01F 7/02 C01G 23/04 G03G 9/08 374 C09C 3/10 CA (STN)

Claims (4)

(57) [Claims] 1. A metal oxide powder having a coating of an organopolysiloxane having an epoxy group as a substituent and a polyalkylenimine. 2. The metal oxide powder according to claim 1, which has a hydrophobicity measured by a transmittance method of 60% or more. 3. The metal oxide powder according to claim 1, wherein the metal oxide is silica, alumina or titania. 4. The metal oxide powder according to claim 1, wherein a hydrophobizing agent other than the organopolysiloxane having an epoxy group as a substituent is used in combination as a treating agent.