US 5,419,928 AGrant
Surface-Modified Pyrogenically Produced Aluminum Oxide
Issue Date:1995-05-30
•1 Claims
•1 Drawing Sheets
Abstract
Surface-modified, pyrogenically produced aluminum oxide which is has the following physico-chemical properties:
Metadata
Assignee
- Degussa Aktiengesellschaft
Inventors
- Hans Deusser
- Dieter Kerner
- Jurgen Meyer
- Gunther Michael
- Andreas Stubbe
Application Information
Application Number:US 1410830
Filing Date:1993-10-26
Priority Date:1992-01-31
Art Unit:112
Classifications
IPC:
B05D 102
Field of Search:
427421;384
Patent Drawings (1 sheets)
Description
The present invention relates to a surface-modified, pyrogenically produced aluminum oxide.
BACKGROUND OF THE INVENTION
It is known to use powdery toners containing pyrogenically produced surface-modified silicon dioxide in electrostatic developing processes. Various silanes, especially dimethyldichlorosilane are used for surface modification (See U.S. Pat. No. 3,720,617).
It is also known that pyrogenically produced silicon dioxide waterproofed with compounds of the general formula ##STR1## can be added to positively chargeable resin powders in order to increase their flowability (See published European Patent Application EP-A 0,293,009).
Published German Patent Application DE-A 12 09 427 discloses aluminum oxide whose surface has been modified with halogen silanes can be added to electrographic developing powders.
Published German Patent Application DE-A 34 26 685 (Canon) teaches the addition of aluminum oxide to positively chargeable toners in which the aluminum oxide has been treated simultaneously witch the adhesion promoter .gamma.-aminopropyltriethoxy- silane and trimethylethoxysilane.
A similarly treated aluminum oxide is described in Published Japanese Patent Application JP-OS 31442 (Nippon Aerosil Corporation).
The known method has the disadvantage that it must use an organic solvent system. Alcohols, hydrocarbons and halogenated hydrocarbons are used as solvents which cannot be completely removed from the reaction product.
SUMMARY OF THE INVENTION
The object of the present invention is to avoid these problems and produce a solvent-free, waterproofed aluminum oxide.
The present invention provides a surface-modified, pyrogenically produced aluminum oxide which is surface modified with a silane mixture consisting of silane A (trimethoxyoctylsilane) and silane B (3-aminopropyltriethoxysilane) having the chemical formulas: ##STR2## The surface-modified, pyrogenically produced aluminum oxide has the following physico-chemical properties:
The present invention also provides a method of producing the surface-modified, pyrogenically produced aluminum oxide in which the .pyrogenically produced aluminum oxide is placed in a mixer and sprayed, with the mixer running, with the mixture of silane A and silane B. The silane and aluminum oxide are mixed after the addition of the silane mixture and, the resulting mixture is tempered at 100.degree. to 150.degree. C., preferably at 115.degree. to 125.degree. C.
The ratio of aluminum oxide to silane mixture can be 0.5 to 40 parts by weight silane mixture per 100 parts by weight aluminum oxide.
The silane mixture can consist of 1 to 99 parts by weight silane A and 99 to 1 parts by weight silane B.
A mixture can be used with preference consisting of 50.+-.20 parts by weight silane A and 50.+-.20 parts by weight silane B.
A particularly suitable aluminum oxide is Aluminum Oxide C which is produced pyrogenically from aluminum trichloride by flame hydrolysis in an oxyhydrogen flame and which has the following physico-chemical characteristics:
The waterproofed aluminum oxide of the invention has the advantage that it has no solvent components. It can be used in toners for copiers.
BRIEF DESCRIPTION OF FIGURE OF DRAWING
The drawing is a graph plotting charge per unit mass as a function of activation time for raw toner and treated toner.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The following examples illustrate the invention.
Example 1
2 kg Al.sub.2 O.sub.3 C produced pyrogenically from aluminum trichloride in an oxyhydrogen flame and having the properties given above are placed in a 135 liter Lodige mixer and sprayed with 100 g of a silane mixture consisting of 50 g trimethoxyoctylsilane and 50 g 3-aminopropyltriethoxysilane with the mixer running. The mixture is mixed for 15 minutes more. The silanized oxide is tempered 2 hours at 120.degree. C.
Physico-chemical properties of the surface-modified aluminum oxide
Example 2
The aluminum oxide waterproofed according to Example 1 is tested in a positive toner system. The toner system consists of the following components:
The repeated activation was tested with this toner and a high charge stability in comparison to the raw toner was determined (see FIG. 1).
Copy-Blau PR is a charge regulating agent for positive toners. It is characterized as follows: Area of application:
1. Charge regulating agents for positive toners (1- or 2-component toners for copiers or laser printers)
2. Clearing agents for black toners
The toner resin used is characterized as follows:
The q/m measurement takes place under the following conditions:
98% carrier (spherical ferrite (80-100 m))
2% aluminum oxide according to Example 1
Activation: Rolling fixture, 360 rpms in 40 ml glass bottle, weighed portion 40 g, developer
Claims
What is claimed is:
1. A method of producing a surface-modified, pyrogenically produced aluminum oxide which has been surface modified with a mixture of silane A and silane B corresponding to the chemical formulas: ##STR3## said surface-modified pyrogenically produced aluminum oxide having the following physico-chemical properties: Surface (m.sup.2 /g) 5 to 150 Stamping Density (g/l) 50 to 90 Drying Loss (%) <5 Annealing Loss (%) 0.5 to 12 Carbon Content (%) 0.5 to 12 pH 4 to 8. ______________________________________ said method comprising placing aluminum oxide in a mixer, spraying the aluminum oxide with a mixture of Silane A and Silane B, mixing the silane mixture and the aluminum oxide, and tempering the resulting mixture at 100.degree. to 150.degree. C., the ratio of silane mixture to aluminum oxide being 0.5 to 40 parts by weight of silane mixture per 100 parts by weight of aluminum oxide.
Patent Citations (5)
Non-Patent Literature (5)
- Translation of JP 58-216252.
- Translation of JP 58-185405.
- Translation of DE 3516937.
- Abstract, JP 58-185405.
- Abstract, JP 58-216252.