JPS58185405A - Fine powder of surface-modified metal oxide - Google Patents

Abstract

PURPOSE:To obtain metal oxide fine powder useful for the improvement of fluidity and the control of electrical charge, by reacting the surface of metal oxide fine powder with an agent for making hydrophobic together with an amino group-containing silane coupling agent, thereby imparting the powder with the hydrophobic property and positive electrical charge. CONSTITUTION:A powdered liquid is prepared by mixing (A) fine powder of metal oxide having a specific surface area of >=50m<2>/g and (B) an organic solvent contaoning (i) a silane coupling agent having amino group and (ii) an agent for making hydrophobic. The amounts of the components (i) and (ii) are 5- 20wt% each based on the metal oxide fine powder, and the weight ratio of (A):(B) is 1:2-5:1. The powdered liquid is heated at >=100 deg.C to obtain surface- modified metal oxide fine powder. The metal oxide is silica, alumina, titania, or their compound oxides and obtained by the vapor-phase hydrolysis. The silane coupling agent is e.g. aluminoalkoxysilane, and the hydrophobing agent is e.g. silazane.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized by reacting both a hydrophobizing agent and an amino group-containing silane coupling agent on the surface of a fine metal oxide powder such as silica, alkoxide, or titania. Adds hydrophobicity and chargeability.

This article relates to fine metal oxide powder, which is used to improve the fluidity of other objects and to examine the electrostatic charge, its manufacturing method, and its uses.

9E rice, hydrophobic silica fine powder is used for fire extinguishing ammonium phosphate powder and epoxy powder paint, 11E
It is added to dry toner for photocopying machines, and is widely used to prevent caking and improve fluidity of these powders.

In many cases, the toner is used with an electrostatic charge applied to it, such as a dry toner for an electrophotographic copying machine, and in this case, the chargeability of the added material also poses a problem. That is, if the toner is to be used with a negative charge, it is desirable to use an additive with a negative charge, and in the opposite case, an additive with a positive charge is desirable. Copying machines that use Cd8 or Cd8 as photosensitive media use negatively charged toner, and negatively charged hydrophobic silica fine powder is used as an additive to improve fluidity.
For example, R972 manufactured by West German Dexa Co., Ltd. has been suitably used (Special Publication No. 16219/16220), but in recent years, the development of inverted dust particles in laser printers and organic optical semiconductors has led to the demand for positively charged toner. As a result, IFi additives with positive or zero chargeability have been required as additives to improve fluidity.

In order to meet this demand, the present inventor attempted to modify the conventional negatively chargeable silica fine powder to be positively chargeable by treating it with amino and silane, but the obtained fine powder did not show hydrophobicity. , failed to achieve its purpose.

＼ Therefore, we continued our research in search of a method to bond more hydrophobizing agents and aminosilane to the surface of fine powder.

When hydrophilic fine powder silica and hydrophobic organic solvent are mixed in a certain limited weight ratio, the hydrophilic fine powder silica surrounds the fine droplets of the hydrophobic organic solvent and turns the liquid into a powder. Focusing on forming a liquid, we attempted to form a powder liquid by dissolving a hydrophobizing agent and a treatment agent such as aminosilane in a nuclear hydrophobic organic solvent. Powder liquid can be handled as a powder, and by using a low boiling point solvent, it can be simply dried under heat and solid-liquid separation is performed without the need for filtration, resulting in extremely uniform application of the processing agent to the raw fine powder. It was discovered that it becomes attached. In this case, if a large amount of organic solvent is used, powder liquid will not be formed, but will become cloudy or emulsified, and it is impossible to separate the fine powder in this state from solid to liquid.
Powder I/i remaining after removing the bath medium by FD thermal drying
The powder will no longer return to the starting # powder. In this respect, the processing method via powder liquid is an extremely superior method, but it has been shown that the obtained metal oxide fine powder exhibits sufficient hydrophobicity and positive chargeability.

That is, according to the present invention, the paper has a 7-mino group and a hydrophobic group on its surface, and the -0H group is blocked and runs, and at least 50? F1″
A low bulk density metal oxide fine powder having a specific surface area of /IP and having a positive or zero surface charge is provided.

To obtain such a modified fine powder, a limited amount of fine powder may be treated with aminosilane and a saccharifying agent separately.

They may be carried out simultaneously, and the key point of the treatment method is to uniformly disperse the treatment agent and fine powder through a powder liquid containing the treatment agent, organic solvent, and fine powder oxide.

That is, according to the present invention, a metal oxide fine powder having a specific surface area of at least 50 m''/?, a silane coupling agent having an amino group, and a hydrophobizing agent are respectively added to the fine powder.
201 is mixed with an organic solvent containing an amount corresponding to the amount of water at a weight ratio of 1:2 to 5:1 to form a liquid.

A method for producing fine metal oxide powder is provided, which comprises heating to 100° C. or higher.

According to the present invention, the toner for an electronic copying machine further has an amino group and a hydrophobic group on its surface in an amount corresponding to 0.1 to 5 weight of the toner, and the -OH group is blocked. It has a specific surface area of at least 50 m''/?

Table 1 provides a method for determining the flowability of the toner by adding a positively or zero-charged low bulk density metal oxide fine powder.

The present invention will be explained in detail below.

In the present invention, starting materials such as fumed silica, alumina, and titania obtained by an acid phase pan-thermal hydrolysis method are silicon.

Aluminum gourds are fine powders with a specific surface area of at least 50 m''/? and missing particles of 50 nm or less.
0J, [Aluminum oxa ()” CJ manufactured by Degussa, West Germany
, rTitanium oxide P-25J.

rMOX170J and the like are suitable. These fine powder oxides have hydroxyl groups on their surfaces.

As explained in F below, it easily bonds with organosilicon compounds through condensation (reaction) or hydrogen bonding, and has a hydrophilic property with a negative surface charge of 4 and a hydrophobic property. and can be changed to zero or positive surface charge.

A so-called hydrophobizing agent for making the surface hydrophobic binds in some way to the hydroxyl group that the low bulk density metal oxide fine powder has on the surface to block it, and also has a hydrophobic group itself. Compounds that are in practical use include silane AIJ agents having hydrophobic groups, silylating agents, and so-called silicone oils having compatibility with -OH groups. Specific examples include silazane, such as hexamethyldisilazane,
Tri-lower alkyl alkoxysilane, such as trimethylethoxysilane, commonly commercially available dimethyl silicone oil (Shin-Etsu Chemical KF96.) - Resilicone 812
00, etc.), methyl hydrogen silicone oil (Shin-Etsu Chemical K
F99. )-Resilicone 5H1107, etc.).

The amount of image processing agent used should be 5 to 20% by weight based on the metal oxide fine powder. If it is less than 5% by weight, the effect of the treatment will not be clear, and if it exceeds 20% by weight, it will not be effective. This is because it becomes saturated.

As the treatment agent selected for the purpose of changing the surface charge to positive, an organic silicon compound having an amino group is suitable. Aminoalkylalkoxysilane. Specifically, γ-aminopropyltriethoxysilane NHs (CHs) ssi
C0CzHs)s (Nippon Unicar A-1100)
, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane NHs (C1h)s NH(CH2h 8% (OCR
s)s (Shin-Etsu Chemical KBM603), γ-(2-aminoethyl)aminopropylmethyldimethoxysilane NH (CHzhNH(CHz)ss IcI(s
(QC) is h ()-Resilico ysZ 6025
), T-anilinopropyltrimethoxysilane Cs
Hs NH(CHs) 381 (OCH3)s (Toray Silicone SZ 6083), etc.; so-called aminosilane coupling agents such as polyethyleneimine-based silane (Tone Silicone 8-6050) have a high reactivity and are not commercially available. It is also easy and convenient to handle.

In order to disperse the treatment agent as uniformly as possible into the Kinpo Oxide 11I powder, it is preferable to dilute the treatment agent with a lubricating organic solvent. type is suitable. Also, for hydrophobizing agents, benzene,
Hydrocarbon solvents such as toluene and hexane, and halogenated hydrocarbon solvents such as carbon tetrachloride and chloroethylene are suitable. If the aminosilane coupling agent and the hydrophobizing agent are treated at the same time and the result is round, there is no excessive solvent to dissolve the internal particles, so it is not compatible with the aminosilane coupling agent and becomes emulsion-like, but it is not compatible with the fine powder. By mixing! Since there is essentially no problem in forming the ξ Miradate liquid, it is preferable to use a hydrocarbon solvent and avoid alcohol a, which would react with hexamethyldisilazane.

The mixing ratio of the dilute solution or emulsion of the treatment agent to the fine powder to be treated is 2:1 to 1:5. should be selected within the range. If the mixing ratio is greater than 2:1, there will be too much solution - will it form a strip? If the ratio is less than 1:5, the solution becomes too small and becomes lumpy, resulting in the formation of powder liquid.

The method of the present invention is to mix the metal oxide fine first wood to be treated with a Wk# agent bath solution containing a silane coupling agent containing a minino group at a weight ratio of 1:2 to 5:1. The zero dispersion time for sufficient mixing and dispersion at room temperature with a mixer equipped with a high-speed stirrer varies depending on the mixer, but a high-speed rotary mixer (8,000O
r, p, m), 3 to 5 minutes is sufficient. It is desirable to add a predetermined amount of the solution by spraying or spraying from the bottom of the mixer while stirring. The resulting oxide fine powder containing the solution mixed and dispersed by the mixer is a fluffy powder butter liquid. Next, this powder liquid is placed in a dryer to completely remove only the solvent contained therein. Heat at 100℃ above the eyebrows for 5 minutes or more. Heating in a bare atmosphere is preferred; it is believed that this heating not only helps remove the solvent but also promotes the reaction. The silane coupling agent containing an amino group is uniformly attached to the nine-fine powder thus obtained. At this stage, the fine powder oxide exhibits a surface charge of plus 10Q to 400V, but there is almost no lI aqueous charge. Next, in the same manner as the above-mentioned treatment with an aminosilane coupling agent, the hexane is removed by treatment with a hydrophobizing agent (e.g., hexamethyldisilazane) diluted with an organic solvent (e.g., hexane), and then the flask is equipped with a reflux condenser. The nine fine powder obtained by heat treatment at 150° C. for 4 hours also exhibits hydrophobicity. When treating with a silane coupling agent and a hydrophobizing agent at the same time, the mixture of these treating agents and an organic solvent becomes an emulsion, which is expressed in a powder liquid by the same operation. The nine mold powder that has been surface-treated in this way has a difference of 100 to 400 V.
It exhibits a surface charge of 100% and exhibits hydrophobicity.

Commonly used ingredients - toner containing gold, i.e., resin powder with a particle size of 5 to 50μ, inorganic powder such as sulfide, nitride, carbon black, and in the case of one-component toner, iron, cobalt, and nickel. When 0.1 to 5 times the surface-modified metal oxide fine powder returned by the above-mentioned method is added to a toner made of magnetic powder such as an alloy or oxide, the fluidity of the toner is improved. It gets much better. Although it is realistic to use IIM to detect the flow out from a funnel with narrow legs as a way to improve IL dynamics, it is possible to add surface-modified metal oxide fine powder to toner to improve the stability of the toner. Comparison of bulk density is also an excellent criterion. In other words, when the degree of "M" increases due to the addition of the fine powder, the a@ property tends to be improved. Similarly, an increase in static bulk density of about 10 to 15 inches is observed.

Another major objective of the present invention is to reduce the amount of electricity in a positively charged toner. This had the disadvantage that the amount of positive charge of the entire toner decreased, but the hydrophobic surface-modified wide area oxide fine powder obtained by the present invention has a positive charge itself as described above. Because of this, fluidity R3 can be maintained without sacrificing the positive charge amount of the entire toner.
Can be used as an additive for L#.

In addition, the amount of charge of the toner to which the fine powder is added is such that the hygroscopicity of the toner itself is extremely reduced due to the hydrophobic effect of the fine powder, and as a result, the charge leakage width due to a single change in the humidity of the outside air is reduced. It shows a constant value for a long period of time throughout the first winter period, and the combined effect of the agglomeration of the toner itself and the hydrophobization effect also increases.

The present invention will be specifically explained below with reference to Examples.

Example 1 20 parts by weight of fumed silica "Aerosil 200J" having a specific surface area of 200 m''/l was placed in a household mixer.
γ-aminoprobyltriethoxysilane (Nippon Unicar Co., Ltd. rA-11
00J) A solution prepared by diluting 2 parts by weight with 20 parts by weight of 90% ethanol is added dropwise using a dropper. After continuing stirring for 3 minutes after completing 7JO, the powder liquid was transferred to a vat and heated at 110°C in a nitrogen gas atmosphere in a dryer.
Heat for 1 hour to remove ethanol. The obtained powder is again placed in a household mixer, and a solution prepared by diluting 4 parts by weight of hexamethyldisilazane with 16 parts by weight of hexane is dispersed in the same manner as described above, and the hexane is removed. The material thus obtained is refluxed in a condenser and a stirrer.

The mixture was transferred to a No. 11 flask containing hot sake and stirred at 150° C. for 4 hours. The obtained fumed silica exhibits hydrophobic conversion of 45 when tested and evaluated by the method described below, and has a t
When testing according to the method described in k.

The surface charge also showed plus 200V.

Further, a small amount of the fine powder before treatment and a small amount of fine powder after treatment were each sandwiched between two NaCl plates to form a thin film, and the infrared absorption spectrum was measured. The results were as shown in Figures 1 and 2. From this result, the absorption based on the 5750m and 6400α OH groups accumulated in the fine powder before treatment in Figure 1 completely disappears in the fine powder treated with aminosilane and a hydrophobizing agent, as shown in Figure 2. 2900
There is only absorption based on the CH3 group near jm, indicating that the OR group is blocked with a hydrophobizing agent.

Example 2 Adding the above r A to 203i parts of the above “Aerosil 200”
An emul obtained by diluting a mixture of 2 parts of -11D O,j and 4 parts by weight of hexamethyldisilazane with 16 parts by weight of hexane:) After mixing and dispersing the mono-form liquid in a home mixer as in Example 1. 150 in the flask after removing the hexane.
The mixture was heated and stirred at ℃ for 4 hours. The obtained nine-layered silica exhibited a degree of hydrophobicity of 401 and a surface charge of 400 V.

Example 3 Humid alumina ``Aluminum Oxide C'' was used instead of ``Aerosil 200'' in Example 1.

N-( instead of r-aminopropyltriethoxysilane
When the same operation was carried out using methanol instead of ethanol with β-aminoethyl) r-aminopropyltrimethoxysilane (Shin-Etsu Chemical KBM 603), hydrophobic alumina with a hydrophobic degree of 551 and a surface electric potential of 7/50V was obtained. It was done.

Example 4 In place of r-aminopropyltriethoxysilane in Example 1, r(2-aminoethyl)aminopropylmethyldimethoxysilane (Toray Silicone Co., Ltd. 8z6025), 1
A similar operation was carried out using methanol as the N solution, and the resulting nine-humed silica was hydrophobicized [50] and had a surface charge of plus or minus 0.

Example 5 In place of “Aerosil 20 mouths” in Example 2, [Aerosil M
When a similar operation was carried out using OX17QJ, a water-dispersible silicon-aluminum co-oxide powder having a degree of hydrophobicity of 400 and a surface charge of 100 V was obtained.

Example 6 When similar insertion was carried out using Hiemed Titania [Titanium Oxide P25] in the layer 9 of "Aerosil 200" in Example 2, the hydrophobicity degree was 40 and the surface 'fIIL impact 4
00v of hydrophobic titanium oxide was obtained.

The test method for each of the fine powders of ferrule oxide in Examples 1 to 6 is as follows.

Hydrophobic degree evaluation test: Put 50 W of distilled water into a 200 yen beaker, and then add the hydrophobic fine powder sample to be evaluated. If the sample is sufficiently hydrophobic, it will completely float on the water surface. While stirring the sample with a small magnetic stirrer, add methanol from a nine-buret tip into the water. As methanol is added, the sample powder that was floating on the water surface gets wet and disperses in the water. I will do it.

The amount of methanol added is read at the point where there are no more floating samples and the sample has completely evaporated.The degree of hydrophobicity is defined by the following formula, with the measured value as aoc.

Therefore, the larger the value of the degree of hydrophobicity, the higher the hydrophobicity, since it will not melt unless it becomes a methanol aqueous solution of lll6#1:.

Surface charge measurement method: Gently pour the sample powder placed in a polyethylene bag onto a grounded aluminum plate, and measure it at a position 5 degrees above using an electrostatic meter "Statiron M" manufactured by MS Sangyo Co., Ltd. .

Fluidity evaluation test fine powder sample 05? was placed in a 500 cm glass container and mixed using a Turbler mixer (manufactured by Ballaholachen, Switzerland) that operates using a gravity blade. The silence [0,55
t/ctnS toner at 25? divided into 4 towns, 90r,
The sample-added toner thus obtained was added while stirring for 1 minute at a time, and then gently placed in a 100 ml graduated cylinder and its weight was measured. The results for the surface-modified metal oxide image powders obtained in Examples 1 to 6 are shown in the following table, in which an increase in static bulk density of 10 to 15 was observed.

In addition, a 1 FIt flow test was conducted using a glass funnel with 5 orifices, and all 9 tests showed good fluidity.

Added fine powder oxide Added amount (excellent weight) Static bulk density (L cold ♂
)0 0.55 Oxide of Example 1 0.5 [16
1 Oxide of Example 2 0.5 0.6
0 Oxide of Example 6 Q, 5 [1
,65 Oxide of Example 4 a5 a
Oxide of 6161 implementation [L5 α
63

[Brief explanation of drawings]

Figures 1 and 2 are infrared absorption spectra of silica before and after treatment by the method of the present invention. Patent applicant Nippon Aerosil Co., Ltd. Agent Patent attorney Masa Matsui Hirodai, cause No. 211 5 friends
IL Danbu (cm-+) procedural amendment (
Method) June 10, 1971 Haruki Shimada, Commissioner of the Japan Patent Office 1 Indication of the case Showa V4+ 57: + Patent 1 No. 068618 2 Title of the invention Surface modified metal oxide fine powder 3 Person making the amendment f Relationship with 'l Patent applicant 1)) [Name, business,) Nippon Aerosil Co., Ltd. 4, Agent 5 Date of supplementary umbrella needle Voluntary action 6 Number of inventions increased by supplement 1E None 7, Subject of amendment The scope of claims and the detailed description of the invention in each column of the specification are amended as follows. "t has an amino group and a hydrophobic group on its surface, and its -OH
base was blocked. A low bulk metal oxide powder having a specific surface area of at least 50 m"/f and having nine surfaces positively or zero charged. 2. The metal oxide fine powder according to claim 1, comprising: The metal oxide is silica, alumina, titania, or a co-oxide of at least two metals of silicon, aluminum, and titanium. (v) The metal oxide fine powder according to claim 2, 4. A metal oxide fine powder having a specific surface area of at least 50 m''/iF, a silane coupling agent having an amino group, and a hydrophobic metal oxide. A powder liquid is formed by mixing the oxidizing agent with a noble organic solvent corresponding to 5 to 20% by weight of the fine powder in a weight ratio of 1:2 to 5:1, and then heated to 100°C or higher. A method for producing fine metal oxide powder, which includes heating. 5. A method for producing metal oxide fine powder according to claim 4, wherein the metal oxide is silica. Alumina, titania, or silicon, aluminum. At least two camphor gold maple co-oxides of titanium. 6% Allowance A method for producing a metal oxide fine powder according to claim 5, wherein the metal oxide is produced by a vapor phase hydration (5) solution method. 7. The method for producing metal oxide fine powder according to claim 4, wherein the silane coupling agent containing an amino group is selected from aminoalkoxysilane and polyethyleneimine-containing silane, and the hydrophobizing agent is derived from silazane, lower alkyl alkoxine, silicone oil, and hydrogenated silicone oil. 8. 0.1 to 5 layers I1 of this toner to toner for electronic copying machine
It has an amino group and a hydrophobic group on its surface corresponding to gJ, and its -OH group is M-chained. At least 50y ('/?
2. A method for improving the fluidity of a skeleton toner comprising adding a low bulk density metal oxide fine powder having a positive or zero charge on two surfaces having a specific surface area of 2. Correct. (a) On page 4, line 5, "chargeability" is corrected to "positive chargeability." (b) Correct “but” on page 6, line 16 to “and”. (C) On page 8, line 4, "the toner that is different" is corrected to "the toner that is different." (d) On page 9, lines 16-19, “The amounts of both processing agents used are...
...This is because it becomes saturated. '' on page 10, lines 17 and 18 [The amounts of both processing agents used are saturated. ] Insert. (・) Correct “home mixer” in lines 2 and 3 on page 17 to “home mixer J.” (f) Correct “magnetic stirrer” in line 4 on page 19 to “
Corrected to Magnetic Stirrer J.

Claims (1)

[Scope of Claims] (t) A low-bulk material having an amino group and a hydrophobic group on its surface, whose -OH group is blocked, and has a specific surface area of at least 50/l, and one surface is positively or zero-charged. Density metal oxide fine powder. 2. The metal oxide fine powder according to claim 1, wherein the metal oxide is silica or alumina. Co-oxides of titania or at least two metals: silicon, aluminum, and titanium. (v) The metal oxide fine powder according to claim 2, wherein the metal oxide is produced by a gas phase hydrolysis method. 4. An organic solvent containing a fine metal oxide powder having a specific surface area of at least 50 m"7#, and an amount of a silane coupling agent and a hydrophobizing agent each having an amino group corresponding to 5 to 20 weight of the fine powder. are mixed in a weight ratio ranging from 1:2 to 5:1 to form a powder liquid;
A method for producing fine metal oxide powder, the method comprising heating to 00°C or higher. 5. A method for producing a fine metal oxide powder according to item 4 of scope of patent sub*, wherein the metal oxide is silica. Alumina, titania, or silicon, aluminum. At least two metal co-oxides of titanium. 6. A method for producing a metal oxide fine powder according to claim 5, wherein the metal oxide is produced by a gas phase hydrolysis method. 7. A method for producing metal oxide fine powder according to claim 4, wherein the silane 4° coupling agent containing an amino group is selected from aminoalkoxysilanes and polyethyleneimine-containing silanes, and @ The hydrating agent is selected from silazane, lower alkyl alkoxysilane, silicone oil, water, and silicone oil. 8 0.1 to 5 weight of the toner for electronic copying machine
It has an amino group and a hydrophobic group on its surface of the neck corresponding to , and its -OH group is blocked. A method for improving the fluidity of the toner, comprising adding a low bulk metal oxide fine powder having a positive or zero surface charge and having a specific surface area of at least 5011 t''/?