U.S. patent application number 09/829014 was filed with the patent office on 2001-11-22 for dispersions containing pyrogenic oxides.
Invention is credited to Golchert, Rainer, Mangold, Helmut, Scharfe, Thomas.
Application Number | 20010042493 09/829014 |
Document ID | / |
Family ID | 8168436 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042493 |
Kind Code |
A1 |
Scharfe, Thomas ; et
al. |
November 22, 2001 |
Dispersions containing pyrogenic oxides
Abstract
Dispersions of pyrogenic oxides, doped using an aerosol, are
prepared by mixing the oxide with a suspending agent and milling.
The dispersions can be used to prepare inkjet paper.
Inventors: |
Scharfe, Thomas; (Alzenau,
DE) ; Golchert, Rainer; (Dieburg, DE) ;
Mangold, Helmut; (Rodenbach, DE) |
Correspondence
Address: |
PILLSBURY WINTHROP LLP
1600 TYSONS BOULEVARD
MCLEAN
VA
22102
US
|
Family ID: |
8168436 |
Appl. No.: |
09/829014 |
Filed: |
April 10, 2001 |
Current U.S.
Class: |
106/482 ;
106/483 |
Current CPC
Class: |
B41M 5/5218 20130101;
C01B 33/1417 20130101; C09D 17/007 20130101 |
Class at
Publication: |
106/482 ;
106/483 |
International
Class: |
C04B 014/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2000 |
EP |
00 107 817.9 |
Claims
What is claimed is:
1. A dispersion comprising a liquid phase and a solid phase,
wherein the solid phase comprises a pyrogenic oxide, and wherein
said pyrogenic oxide: a) is doped with one or more doping
components; and b) has a BET surface area of between 5 and 600
m.sup.2/g.
2. The dispersion of claim 1, wherein said pyrogenic oxide is
silica.
3. The dispersion of claim 1, wherein said liquid phase is
water.
4. The dispersion of any one of claims 1-3, wherein said pyrogenic
oxide is prepared by the method of flame hydrolysis or flame
oxidation.
5. The dispersion of any one of claims 1-3, wherein said pyrogenic
oxide is doped using an aerosol.
6. The dispersion of any one of claims 1-3, wherein said pyrogenic
oxide is doped with aluminum oxide.
7. The dispersion of any one of claims 1-3, wherein the amount of
doped material in said pyrogenic oxide is between 1 and 200,000
ppm.
8. The dispersion of claim 6, wherein the amount of doped material
in said pyrogenic oxide is between 1 and 200,000 ppm.
9. The dispersion of claim 8, wherein said doped material is
applied as a salt or a salt mixture.
10. The dispersion of any one of claims 1-3, wherein the solid
phase in the dispersion is present in a proportion by weight of
between 0.001 and 80 wt. %.
11. The dispersion of claim 6, wherein the solid phase in the
dispersion is present in a proportion by weight of between 0.001
and 80 wt. %.
12. A process for preparing a dispersion according to claim 1,
comprising: a) mixing a doped pyrogenic oxide with a liquid; and b)
milling the mixture produced in step a).
13. The process of claim 12, wherein said liquid is water and said
pyrogenic oxide is silica.
14. The process of claim 12, wherein said pyrogenic oxide is
present in said liquid in a proportion by weight of between 0.001
and 80 wt. %.
15. The process of claim 12, wherein said milling procedure is
performed using an ball mill.
16. The process of claim 12, wherein said milling procedure is
performed using a pearl mill.
17. The process of claim 12, wherein said milling procedure is
performed using a high pressure milling mixture.
18. A coating mixture for an inkjet paper or inkjet film comprising
the dispersion of claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to Europen
application 00107817.9 filed on Apr. 12, 2000, the subject matter
of which is hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention is directed to dispersions, a process
for preparing these dispersions and their use in the preparation of
coating mixtures for inkjet media.
BACKGROUND OF THE INVENTION
[0003] It is known that dispersions, for example water-based
dispersions, can be prepared from pyrogenically prepared oxides.
Aqueous dispersions can be used to prepare coating mixtures which
are applied to paper or films. The coated films may then be printed
using an inkjet printer. In this case, one objective is to obtain
dispersions which are filled as highly as possible (high solids
content) but with a low viscosity.
SUMMARY OF THE INVENTION
[0004] The invention provides dispersions which are characterised
in that they consist of a liquid phase, preferably water, and a
solid phase. The solid phase consists of a pyrogenic oxide, doped
using an aerosol, the BET surface area of which is between 5 and
600 m.sup.2/g. The pyrogenic oxide preferably comprises silica
prepared by the method of flame hydrolysis or flame oxidation and
which has been doped with one or more doping component(s).
Preferably the doping component is an aluminium oxide, and doping
is accomplished by the method of aerosol application, in which the
amount of doped material is between 1 and 200,000 ppm and the
doping component(s) are applied via a salt or a salt mixture. The
solid phase in the dispersion should be present in a proportion by
weight between 0.001 and 80 wt. %.
[0005] The invention also provides a process for preparing chemical
dispersions in which a pyrogenic oxide, doped using an aerosol, is
introduced into a liquid, preferably water, in a proportion by
weight of between 0.001 and 80 wt. %. This dispersion is then that
patent, 85 kg/h of SiCl.sub.4 are evaporated, mixed with 51
Nm.sup.3/h of hydrogen and with 70 Nm.sup.3/h of a nitrogen/oxygen
mixture (containing 35 vol. % O.sub.2, remainder N.sub.2) and fed
into the central tube in the burner. The gas mixture flows out of a
nozzle and bums in a water-cooled combustion chamber. 4 Nm.sup.3/h
of (jacket) hydrogen flows out of the jacket nozzle which surrounds
the central nozzle, in order to avoid incrustations. 70 Nm.sup.3/h
of secondary air are also introduced into the combustion
chamber.
[0006] An aerosol flows into the central tube out of an axial tube
located therein. The aerosol is produced by atomising a 15% aqueous
AlCl.sub.3 solution using a two-fluid nozzle. An aerosol flow of 1
kg/h (aqueous salt solution) is produced in which a carrier gas
stream of 16 Nm.sup.3/h of air conveys the aerosol through a
heating section. The air/aerosol gas mixture then enters the
central tube from the axial tube at about 180.degree. C. The
aerosol is burned together with the air/SiCl.sub.4 mixture. The
reaction gases and the pyrogenically prepared silica doped with
aluminium oxide are removed under suction through a cooling system,
and cooled by applying a reduced pressure. The solid material
(doped pyrogenic oxide) is separated from the gas stream in a
filter or a cyclone.
[0007] The doped pyrogenically prepared silica is produced as a
white, finely divided powder. Adhering residues of hydrochloric
acid are removed by treatment at elevated temperature with air
which contains water vapour. The pyrogenic silicon dioxide doped
using an aerosol has the following physico-chemical
characteristics:
1 BET: 60 m.sup.2/g pH (4% aqu. disp.): 3.9 Compacted bulk density:
142 g/l Chloride content: 180 ppm Al.sub.2O.sub.3 content 0.19 wt.
% DBP absorption: 73 g/100 g (DBP: dibutyl plithalate)
[0008] An aqueous dispersion is prepared with the doped pyrogenic
oxide. A commercially available Aerosils (pyrogenically prepared
silica) provided by Degussa-Huls AG/Frankfurt, OX 50 and Aerosil
90, are used as comparison examples.
[0009] Table 1 gives the characteristics of the oxides:
2TABLE 1 Physico-chemical characteristics of the doped pyrogenic
oxide Doped pyrogenic oxide according to example OX 50 Aerosil 90
BET m.sup.2/g 60 50 90 pH (4% aqu. disp.) 3.9 3.8-4.8 3.7-4.7
Compacted bulk density 142 130 80 g/l Chloride content 180 <250
<250 ppm Al.sub.2O.sub.3 content wt. % 0.19 <0.08 0.05
SiO.sub.2 content wt. % 99.8 >99.8 >99.8
[0010] An aqueous dispersion is prepared using these three
different pyrogenic oxides. This is achieved using a rotor-stator
system (Ultra-Turrax.TM.) with a dispersion time of 30 minutes in a
double-walled vessel with water cooling. It is attempted to prepare
a 40% (with respect to solids) dispersion (w=0.40). This dispersion
may also be prepared using other equipment, e.g., ball mills or
pearl mills or various types of jet or high-pressure mills (jets of
liquid directed towards each other). It is shown that it is not
possible to produce a 40% dispersion with Aerosil 90 using this
system because the system is too highly viscous. The viscosity of
the dispersions prepared in this way (doped oxide and Aerosil OX
50) is measured after 2 h with a Brookfield viscometer.
3TABLE 2 Viscosity of the 40% aqueous dispersion Doped pyrogenic
Aerosil 90: oxide according not possible to prepare a 40% to
example 1 OX 50 dispersion using Ultra-Turrax 5 rpm 2420 2320
>10,000 l0 rpm 1520 1320 20 rpm 970 745 50 rpm 554 372 100 rpm
370 256 rpm = revolutions per minute of the Brookfield
viscometer
[0011] Inkjet coating mixtures are prepared from these 40% aqueous
dispersions. Formulation for preparing an inkjet coating mixture is
as follows. Two dispersions, A and B, are prepared. Dispersion A is
a 40% (w=0.40 ) aqueous dispersion which contains the pyrogenic
oxide (or the doped pyrogenic oxide). This is made by dispersing
the pyrogenic oxide or doped oxide for 30 minutes with an
Ultra-Turrax system in a water-cooled double-jacket system.
[0012] Dispersion B is a 10% (with respect to PVA) aqueous
dispersion of polyvinyl alcohol (solid, abbreviated as PVA), Mowiol
26-88 from the Clariant Co. The two dispersions A and B are
combined over the course of 10 minutes by stirring at 500 rpm with
a dissolver disc to give a dispersion C. Dispersions A and B are
mixed in such a way that a ratio by weight of Aerosil (or doped
pyrogenic oxide) to PVA of 100:20 is produced in subsequent
dispersion C. In the case of a 40% dispersion A, this is mixed with
dispersion B in the ratio by weight of 1.25:1 in order to achieve
the required ratio by weight (100:20 for the solids). Furthermore
(if required) enough water is added to produce a 24% dispersion C,
with respect to the sum of the solids (progenic oxide+ PVA). The
viscosity of this dispersion C, the inkjet coating mixture, is
measured after 24 h using a Brookfield viscometer.
4TABLE 3 Viscosity of the coating mixture measured after 24 h Doped
oxide according to example 1 OX 50 Aerosil 90 Solids content of the
24 24 22.5 coating mixture (pyrogenic oxide + PVA) wt. % Viscosity
[mPas] 3244 685 3352 at 100 rpm (Note: In the case of preparing the
coating mixture from Aerosil 90, a 30% aqueous dispersion is used
initially.)
[0013] (Note: In the case of preparing the coating mixture from
Aerosil 90, a 30% aqueous dispersion is used initially.)
[0014] These coating mixtures are applied to an untreated polyester
film (thickness 100 micrometers) with the aid of a shaped spreading
rod. The wet film thickness of the coating mixture is 120
micrometers. The coating is dried at 105.degree. C. for 8 minutes.
The also very good. Although dispersions made with Aerosil OX 50
also have a relatively low viscosity, the print quality of the
coating mixtures, or coatings, prepared therefrom is not
acceptable.
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