U.S. patent application number 13/157045 was filed with the patent office on 2011-11-24 for chemomechanical manufacture of functional colloids.
This patent application is currently assigned to BUEHLER PARTEC GMBH. Invention is credited to Jens Adam, Kai Gossmann, Helmut Schmidt, Karl-Peter Schmitt, Frank Tabellion.
Application Number | 20110288183 13/157045 |
Document ID | / |
Family ID | 32730819 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110288183 |
Kind Code |
A1 |
Adam; Jens ; et al. |
November 24, 2011 |
CHEMOMECHANICAL MANUFACTURE OF FUNCTIONAL COLLOIDS
Abstract
A method for producing a functional colloid during which
particles are reactively fragmented in a mechanical manner in a
dispersant in the presence of a modifying agent so that the
modifying agent is chemically bound, at least in part, to the
fragmented colloid particles.
Inventors: |
Adam; Jens; (Saarbruecken,
DE) ; Gossmann; Kai; (Saarbruecken, DE) ;
Schmidt; Helmut; (Saarbruecken, DE) ; Schmitt;
Karl-Peter; (Grosbliederstrof, FR) ; Tabellion;
Frank; (Saarbruecken, DE) |
Assignee: |
BUEHLER PARTEC GMBH
Saarbruecken
DE
|
Family ID: |
32730819 |
Appl. No.: |
13/157045 |
Filed: |
June 9, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10544003 |
Jul 29, 2005 |
7989504 |
|
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PCT/EP2004/001121 |
Feb 6, 2004 |
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13157045 |
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Current U.S.
Class: |
516/100 |
Current CPC
Class: |
C04B 2235/483 20130101;
C09C 1/3623 20130101; C09C 3/12 20130101; C04B 2235/5445 20130101;
Y10S 516/924 20130101; C01P 2004/64 20130101; C04B 2235/5409
20130101; C09C 3/006 20130101; C04B 2235/5454 20130101; C09C 3/08
20130101; C04B 35/62886 20130101; Y10S 516/928 20130101; B82Y 30/00
20130101; C01P 2006/12 20130101; B01J 13/0086 20130101; C04B
35/62615 20130101; C09C 1/407 20130101; Y10S 977/776 20130101; C09C
1/3692 20130101; C04B 2235/5436 20130101; C04B 35/62655 20130101;
C09C 1/3684 20130101; C01P 2004/62 20130101; C09C 3/041 20130101;
C04B 35/632 20130101; C04B 35/628 20130101; C04B 2235/349 20130101;
Y10T 428/2982 20150115 |
Class at
Publication: |
516/100 |
International
Class: |
B01J 13/00 20060101
B01J013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2003 |
DE |
10304849.9 |
Claims
1-16. (canceled)
17. A method for the chemomechanical manufacture of a functional
colloid, comprising the steps of: manufacturing particles by flame
pyrolysis; and subjecting the particles to mechanical reactive
comminution in a dispersant in the presence of a modifying agent to
produce comminuted colloid particles, wherein the modifying agent
is at least partially chemically bound to the comminuted colloid
particles.
18. The method of claim 17, wherein the modifying agent is a silane
having the general formula (l) R.sub.aSiX(.sub.4-a) (l) wherein
residues R are the same or different, and represent
non-hydrolyzable groups, residues X are the same or different, and
represent hydrolyzable groups of hydroxy groups, and a has the
value 1, 2 or 3.
19. The method of claim 18, wherein the residue R is selected from
the group consisting of alkyl, alkenyl, aryl and combinations
thereof.
20. The method of claim 18, wherein the residue R has a functional
group selected from epoxide, hydroxy, ether, amino, monoalkyl
amino, dialkyl amino, anilino, amide, carboxy, acryl, acryloxy,
methacryl, methacryloxy, mercapto, cyano, alkoxy, isocyanato,
aldehyde, alkyl carbonyl, and acid anhydride.
21. The method of claim 19, wherein the residue R at least
partially exhibits organic residues, which are substituted with
fluorine.
22. The method of claim 20, wherein the residue R at least
partially exhibits organic residues, which are substituted with
fluorine.
23. The method of claim 20, wherein the residue R at least
partially exhibits organic residues, which are substituted with
fluorine.
24. The method of claim 17, wherein reactive comminution of the
particles is carried out in a mill with loose milling bodies.
25. The method of claim 24, wherein the milling bodies have a
diameter not to exceed 2.5 mm.
26. The method of claim 17, wherein reactive comminution includes
providing the dispersant according to the jet nozzle principle.
27. The method of claim 17, wherein the modifying agent is bound to
the colloid particles via hydrogen bridges, either covalently,
ionically or coordinatively.
28. The method of claim 17, wherein the modifying agent has a
molecular weight not to exceed 500.
29. The method of claim 17, wherein the formed colloid particles
have an average smallest dimension not to exceed 0.2 .mu.m.
30. The method of claim 17, wherein the modifying agent in the
dispersant exhibits no surfactant properties.
31. The method of claim 17, wherein the modifying agent is selected
from the group consisting of a silane, a carbonic acid, an
aminocarbonic acid, an amine and mixtures thereof.
32. The method of claim 17, wherein the modifying agent is also
used as the dispersant.
33. The method of claim 17, wherein reactive comminution is carried
out in a comminution machine and is provided by an additional
supply of energy to the dispersion, wherein the additional energy
is supplied directly in the comminution machine.
34. The method of claim 17, wherein reactive comminution is carried
out in a comminution machine and is provided by an additional
supply of energy to the dispersion, wherein the additional energy
is supplied directly outside the comminution machine.
35. The method of claim 33, wherein the additional energy supply
takes place via ultrasound and/or microwaves.
36. The method of claim 34, wherein the additional energy supply
takes place via ultrasound and/or microwaves.
37. The method of claim 17, further comprising removing the
dispersant after manufacture of the functional colloid.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the continuation of U.S. patent
application Ser. No. 10/544,003, filed Jul. 29, 2005 which is a
U.S. national phase of International Application No.
PCT/EP2004/001121 filed Feb. 6, 2004 which claims priority of
German Application No. 10 304849.9 filed Feb. 6, 2003.
BACKGROUND OF THE INVENTION
[0002] This invention relates to functional colloids and a method
for their manufacture.
[0003] Colloids have been known for a long time. They can arise,
for example, via sol-gel technique, or in natural processes, such
as in bodies of water and during condensation processes in the gas
phase. It is typical for such colloids that they are only stable in
an aqueous solution if prevented from aggregating via stabilizing
factors. Aggregation can be initiated through interactions between
the colloid particles, e.g., via van-der-Waals forces, hydrogen
bridges, hydrophobic interactions, dipole-dipole-interactions or
chemical bonds. Given the extremely large surface, the tendency
toward aggregation is particularly great. Colloidal particle
normally have dimensions not exceeding 0.2 .mu.m.
[0004] In general, colloid stabilization takes place via a
corresponding zeta potential, i.e., the formation of a dual charge
cloud around the colloid. This can be caused by a varying electron
affinity, or a charging of particles with ions or electrons, e.g.,
by setting the pH value. However, it can also take place via the
agglomeration of specific molecules on the surface, e.g., via the
agglomeration of humic acid in natural bodies of water. However,
all of these processes assume that the colloids have been generated
by a preceding reaction, and that conditions leading to such a
stabilization have been established in the environment of the
colloid.
[0005] While other methods for manufacturing small particles, e.g.,
high-energy milling, shatter the crystalline structure down to
nanoscale proportions, they cannot prevent subsequent aggregation.
Such aggregated particles, which are in part also manufactured via
targeted condensation from gas phases, can only be deaggregated
under specific conditions. For example, metal particles have been
successfully dispersed in oil, since the oil can shift between
weakly interacting metal surfaces. However, weakly interacting
metal surfaces are only obtained if the metal particles are
fabricated in a high vacuum, i.e., under ultra-pure conditions, so
that no oxide surface is formed. If this is not the case, it
becomes practically impossible to disperse the particles any
longer. In the aforementioned high-energy milling process, a
redispersion to primary crystallite size is hence no longer
possible.
[0006] As shown above for metal particles redispersible in oil,
such systems can only be controlled from a process standpoint in
exceptional cases. Process control requires a method that sets the
colloid particles during manufacture in such a way that they
satisfy the respective process-related requirements. In this way,
it would be possible to impart the desired properties or functions
to the colloid particles during manufacture. For example, it would
be possible to stabilize, compatibilize, intertize or reactivate
the colloid particles relative to the environment.
[0007] Commercially available milling aggregates commonly only make
it possible to obtain particles in the submicrometer range, and
even that only with so-called milling aids, which prevent freshly
generated fractured surfaces from recombining again. Comminution to
colloidal dimensions, in particular to a range of 0.002 to 0.05
.mu.m, is generally not possible.
[0008] The object according to the invention was now to fabricate
colloids that exhibit an outstanding stability relative to
aggregation, wherein the colloid particles can be extremely small
(preferably under 0.2 .mu.m, in particular under 0.05 .mu.m), and
the properties or functions of the colloid or colloid particles can
be adjusted to the respective requirements.
SUMMARY OF THE INVENTION
[0009] The object according to the invention is achieved by using a
chemomechanical reactive comminution process to realize a
functionalization, accompanied simultaneously by stabilization
relative to an aggregation of the obtained colloid particles.
DETAILED DESCRIPTION
[0010] Accordingly, this invention provides a method for the
chemomechanical manufacture of a functional colloid, in which
particles are subjected to mechanical reactive comminution in a
dispersant in the presence of a modifying agent, so that the
modifying agent is at least partially chemically bound to the
comminuted colloid particles.
[0011] According to the invention, generally low-molecular
modifying agents that can enter into a chemical bond with the
particles are used in milling aggregates or other dispersing
aggregates to generate functional colloids out of particles, which
exhibit molecular residues of the modifying agent rigidly bound
with the surface of the particles as functional groups, wherein the
average smallest dimension of the functionalized particles can
extend as far down to 0.01 and even 0.002 .mu.m, if needed. The
method according to the invention makes it possible to obtain
stable colloids with average smallest dimensions preferably not
exceeding 0.2 .mu.m from coarse-grained particles. Modifying the
colloid particles with comparatively small molecules that can
rapidly diffuse on the newly formed surfaces prevents or inhibits
an aggregation, while at the same time resulting in a
functionalization of the colloid or colloid particles tailored to
the respective requirements.
[0012] The used particles are solid particles made out of any
suitable material. For example, they can be organic (or polymer) or
inorganic particles, wherein inorganic particles are preferred.
Examples of inorganic particles include particles consisting of an
element, an alloy or an element compound. The inorganic particles
preferably consist of metals, alloys and in particular of metal
compounds and semiconductor element compounds, e.g., Si or Ge, or
boron.
[0013] Examples for particles from an element are particles from
carbon, like soot or activated charcoal, from a semiconductor, like
silicon (including industrial Si, ferrosilicon and pure silicon) or
germanium or a metal such as iron (also steel), chromium, tin,
copper, aluminum, titanium, gold and zinc. Examples of particles
from an alloy include particles from bronze or brass.
[0014] Examples for preferred metal compounds and compounds of
semiconductor elements or boron include (if necessary, hydratized)
oxides, such as ZnO, CdO, SiO.sub.2, GeO.sub.2, TiO.sub.2,
ZrO.sub.2, CeO.sub.2, SnO.sub.2, Al.sub.2O.sub.2 (in all
modifications, in particular as a corundum, bomite, AlO(OH), also
as aluminum hydroxide), In.sub.2O.sub.2, La.sub.2O.sub.3,
Fe.sub.2O.sub.3, Cu.sub.2O, Ta.sub.2O.sub.5, Nb.sub.2O.sub.5,
V.sub.2O.sub.5, MoO.sub.3 or WO.sub.3, corresponding mixed oxides,
e.g., indium tin oxide (ITO), antimony-tin oxide (ATO),
fluorine-doped tine oxide (FTO) and those with a perowskite
structure, such as BaTiO.sub.3 and PbTiO.sub.2, chalcogenides, for
example sulfides (e.g., CdS, ZnS, PbS and Ag2S), selenides (e.g.,
GaSe, CdSe and ZnSe) and tellurides (e.g., ZnTe or CdTe),
halogenides, such as AgCl, AgBr, Agl, CuCl, CuBr, Cdl.sub.2 and
Pbl.sub.2, carbides, such as CdC2 or SiC, silicides, such as
MoSi.sub.2, arsenides, such as AlAs, GaAs and GeAs, antimonides,
such as InSb, nitrides, such as BN, AlN, Si.sub.3N.sub.4 and
Ti.sub.2N.sub.4, phosphides, such as GaP, InP, Zn.sub.3P.sub.2 and
Cd.sub.2P.sub.2, as well as carbonates, sulfates, phosphates,
silicates, zirconates, aluminates and stannates of elements, in
particular of metals or Si., e.g., carbonates of calcium and/or
magnesium, silicates, such as alkali silicates, talcum,
clays(kaolin) or mica, and sulfates of barium or calcium. Other
examples of expedient particles include magnetite, maghemite,
spinelles (e.g., MgO.Al.sub.2O.sub.3), mullite, eskolaite, tialite,
SiO.sub.2.TiO.sub.2, or bioceramics, e.g., calcium phosphate and
hydroxyapatite. They can also be particles made of glass or
ceramics.
[0015] They can also be particles that are usually used to
manufacture glass (e.g., borosilicate glass, soda-lime glass or
silica glass), glass ceramics or ceramics (e.g., based on the
oxides SiO.sub.2, BeO, Al.sub.2O.sub.2, ZrO.sub.2 or MgO or the
corresponding mixed oxides, electro- and magnetoceramics, such as
titanates and ferrites, or non-oxide ceramics, such as silicon
nitride, silicon carbide, boronitride or borocarbide). The
particles can also serve as fillers or pigments. Technically
important fillers include fillers based on SiO.sub.2, such as
quartz, cristobalite, tripolite, novaculite, diatomite, silica,
pyrogenic silicic acids, precipitated silicic acids and silica
gels, silicates, such as talcum, pyrophyllite, kaolin, mica,
muscovite, phlogopite, vermiculite, wollastonite and perlite,
carbonates, such as calcites, dolomites, chalk and synthetic
calcium carbonates, soot, sulfates, such as light spar and heavy
spar, iron mica, glasses, aluminum hydroxides, aluminum oxides and
titanium dioxide.
[0016] Mixtures of these particles can also be used. Especially
preferred materials for the particles are metal oxides, silicon
oxides and silicates, in particular talcum, ZrO.sub.2,
Al.sub.2O.sub.2, TiO.sub.2 and SiO.sub.2 or mixtures thereof.
[0017] The particles used according to the invention can be
manufactured in a conventional manner, e.g., via flame pyrolysis,
plasma procedures, gas-phase condensation procedures, colloid
techniques, precipitation procedures, sol-gel processes, controlled
nucleation and growth processes, MOCVD processes and
(micro)emulsion procedures. These methods are extensively described
in the literature. In particular, use can be made of metals (e.g.,
after the reduction of the precipitation procedure), ceramic oxide
systems (via deposition from solution), along with salt-like
systems or multi-component systems.
[0018] The useable particles are generally frequently available on
the market as well. Examples of SiO.sub.2 particles include
commercially available silicic acid products, e.g., silica sols,
such as Levasile.RTM., silica sols from Bayer AG, or pyrogenic
silicic acids, e.g., the Aerosil.RTM. products from Degussa. Of
course, all particles to be used as fillers can normally be
procured on the market.
[0019] The particles can be used in the form of a powder or
directly as a dispersion in a dispersant. The particles can also be
obtained in the dispersant via the deposition of a dissolved
prestage in situ.
[0020] The particle size of the used particles generally exceeds
that of the colloid particles obtained via the method according to
the invention. Even though the particle size of the used particles
can be selected as desired, particles with an average particle
diameter of less than 100 .mu.m, preferably less than 10 .mu.m, and
an average particle diameter exceeding 0.001 .mu.m, preferably
exceeding 0.01 .mu.m, are expedient.
[0021] The dispersant can be any solvent desired, provided it does
not or essentially does not dissolve the particles to be treated,
and is also inert or essentially inert relative to the used
modifying agent. The suitable dispersant is preferably selected
form water or organic solvents, depending on the particles to be
treated, but inorganic solvents are also possible, such as carbon
disulfide.
[0022] One particularly preferred dispersant is water, e.g.,
deionized water. Suitable organic dispersants include both polar
and nonpolar and aprotic solvents. Examples include alcohols, e.g.,
aliphatic and alicyclic alcohols with 1 to 8 carbon atoms (in
particular methanol, ethanol, n- and i-propanol, butanol, octanol,
cyclohexanol), ketones, e.g., aliphatic and alicyclic ketones with
1 to 8 carbon atoms (in particular acetone, butanone and
cyclohexanone), etsters, e.g., acetic acid ethyl esters and glycol
esters, ethers, e.g., diethyl ether, dibutyl ether, anisol,
dioxane, tetrahydrofurane and tetrahydropyrane, glycol ethers, such
as mono, di, tri and polyglycol ethers, glycols, such as ethylene
glycol, diethylene glycol and propylene glycol, amides and other
nitrogen compounds, e.g., dimethyl acetamide, dimethyl formamide,
pyridine, N-methylpyrrolidine and acetonitrile, sulfoxides and
sulfones, e.g., sulfolan and dimethyl sulfoxide, nitro compounds,
such as nitrobenzene, halogen hydrocarbons, such as
dichloromethane, chloroform, tetrachlorocarbon, tri,
tetrachloroethene, ethylene chloride, chlorofluorocarbons,
aliphatic, alicyclic or aromatic hydrocarbons, e.g., with 5 to 15
carbon atoms, e.g., pentane, hexane, heptane and octane,
cyclohexane, benzine, petroleum ether, methylcyclohexane, decalin,
terpene solvents, benzene, toluene and xylenes. Of course, mixtures
of such dispersants can also be used.
[0023] Preferably used organic dispersants include aliphatic and
alicyclic alcohols, such as n- and i-propanol, glycols, such as
ethylene glycol, and aliphatic, alicyclic and aromatic
hydrocarbons, such as hexane, heptane, toluene and o-, m- and
p-xylene. Particularly preferred dispersants are ethanol and
toluene.
[0024] The particles are subjected to mechanical reactive
comminution in the dispersant in the presence of a modifying agent,
i.e., mechanical comminution is accompanied by a chemical binding
of the modifying agent to the particles or comminuted particles in
a chemical reaction. Such a reaction under a mechanical load is
also referred to as a chemomechanical reaction. As known to the
expert, the surface of particles usually has groups that cannot be
found in this form inside the particles. These surface groups
usually involve functional groups, which are generally relatively
reactive. For example, such particles have surface groups like
residual valences, e.g., hydroxy groups and oxy groups, e.g., in
the case of metal oxide particles, or thiol groups and thio groups,
e.g., in the case of metal sulfides, or amino-, amide- and imide
groups, e.g., in the case of nitrides.
[0025] In particular, the modifying agent has a functional group
that can enter into a chemical bond with the surface groups of the
particles, at least under conditions of mechanical comminution. The
chemical bond preferably involves a covalent, ionic or a
coordinative bond between the modifying agent and the particle, but
can also be hydrogen bridge bonds. Coordinative bonds are
understood to a complex formation. For example, an acid/base
reaction according to Bronsted or Lewis, complex formation or
esterification can take place between the functional groups of the
modifying agent and the particles.
[0026] The functional group encompasses the modifying agent, and
preferably involves carbonic acid groups, acid chloride groups,
ester groups, nitrile and isonitrile groups, OH groups, SH groups,
epoxide groups, anhydride groups, acid amide groups, primary,
secondary and tertiary amino groups, Si--OH groups, hydrolysable
residues of silanes (the following described Si--OR groups) or C--H
acid groupings, as in .beta.-dicarbonyl compounds.
[0027] The modifying agent can also encompass more than one such
functional group, e.g., in betaines, amino acids, EDTA.
[0028] In one variant of the method according to the invention, the
used modifying agent can simultaneously also serve as a dispersant,
so that the same bond can be used for both.
[0029] The modifying agents are not surfactants. This means that
the modifying agent in the solvent used as the dispersant is unable
to form micelles, even when used in high concentrations. The
modifying agent used according to the invention, which differs from
a surfactant, dissolves homogeneously in the solvent used as the
dispersant. The modifying agents then are present as discrete
molecules or molecule ions, homogeneously distributed in the
solution. By contrast, surfactants in a solvent accumulate at an
interface at a low concentration, lower the interfacial tension,
and at high concentrations form micelles, meaning that they are
heterogeneously distributed. The above information relates to the
behavior in a pure dispersant. In the presence of particles, the
modifying agents naturally enter into the chemical interactions
with the particles as described in the invention.
[0030] While the modifying agents at least in part enter into
covalent, ionic or coordinative chemical bonds with the surface
groups of the particles as indicated above, the interactions of
surfactants are generally less specific, e.g., typically involve
adsorption or wetting interactions.
[0031] In addition to the at least one functional group that can
enter into a chemical bond with the surface group of the particle,
the modifying agent generally has a molecular residue, which
modifies the properties of the particle after linking the modifying
agent via the functional group. The molecular residue, or a portion
thereof, can be hydrophobic or hydrophilic, for example, or carry a
second functional group, so as to in this way functionalize the
colloid particles relative to the environment, i.e., e.g.,
stabilize, compatibilize, intertize or reactivate. In this way, the
colloid particles obtained according to the invention are provided
by this molecular residue with a function or surface
functionalization. In this sense, the colloids from the colloid
particles modified with the modifying agent or surface modifying
agent involve functional colloids. The invention makes it possible
to obtain functional colloids tailored to the desired application.
Depending on the system, covalent bonds, ionic bonds and complex
bonds can be present as principles for coupling to the particles,
while hydrogen bridge bonds are also suitable.
[0032] Hydrophobic molecular residues can include alkyl, aryl,
alkaryl, aralkyl or fluorine-containing alkyl groups, which can
lead to intertization or rejection given a suitable environment.
Examples for hydrophilic groups would be hydroxy-, alkoxy- or
polyether groups. If present, the second functional group of the
modifying agent can be an acid, base or ionic group. It can also be
a functional group suitable for a chemical reaction with a selected
reactant. Since the second functional group can be the same as the
one also suitable as a functional group for binding to the
particle, reference is made to the examples cited there. Other
examples for a second functional group include epoxide, acryloxy-,
methacryloxy-, acrylate or methacrylate groups. There can be two or
more identical or different functional groups of this kind.
[0033] The modifying agent preferably has a molecular weight not
exceeding 500, more preferably not exceeding 400, and especially
not exceeding 200. The bonds are preferably liquid under normal
conditions. The functional groups that carry these bonds primarily
depend on the surface groups of the solid particles and the desired
interaction with the environment. The molecular weight also plays
an important role with respect to diffusion on the freshly formed
particle surfaces. Small molecules result in a rapid occupation of
the surface, thereby preventing recombination.
[0034] Hence, examples of suitable modifying agents include
saturated or unsaturated mono- and polycarbonic acids, the
corresponding acid anhydrides, acid chlorides, esters and acid
amides, amino acids, imines, nitriles, isonitriles, epoxy
compounds, mono- and polyamines, .beta.-dicarbonyl compounds,
silanes and metal compounds, which have a functional group that can
interact with the surface groups of the particles. Particularly
preferred modifying agents include silanes, carbonic acids, amino
acids and amines. The carbon chains of these compounds can be
interrupted by O-, S- or NH-groups. One or more modifying agents
can be used.
[0035] Preferred saturated or unsaturated mono- and polycarbonic
acids (preferably monocarbonic acids) are ones with 1 to 24 carbon
atoms, e.g., formic acid, acetic acid, propionic acid, butyric
acid, valeric acid, caproic acid, acrylic acid, methacrylic acid,
crotonic acid, citric acid, adipic acid, succinic acid, glutaric
acid, oxalic acid, maleic acid, fumaric acid, itoconic acid and
stearic acid, as well as the corresponding acid hydrides,
chlorides, esters and amides, e.g., caprolactam. The aforementioned
carbonic acids also encompass those whose carbon chains are
interrupted by O-, S- or NH-groups. Especially preferred are ether
carbonic acids, such as mono- and polyether carbonic acids, as well
as the corresponding acid hydrides, chlorides, esters and amides,
e.g., methoxyacetic acid, 3,6-dioxaheptanic acid and
3,6,9-trioxadecanic acid.
[0036] Examples of preferred mono- and polyamines are those with
the general formula Q.sub.3-nNHn, wherein n=0, 1 or 2, and the
residues Q independently represent alkyl with 1 to 12, in
particular 1 to 6, and especially preferred 1 to 4 carbon atoms,
e.g., methyl, ethyl, n- and i-propyl and butyl, as well as aryl,
alkaryl or aralkyl with 6 to 24 carbon atoms, e.g., phenyl,
naphthyl, tolyl and benzyl, and polyalkylene amines with the
general formula YiN(--Z--NY).sub.y--Y, wherein Y is independently Q
or H, wherein Q is defined as above, y is a whole number from 1 to
6, preferably 1 to 3, and Z is an alkylene group with 1 to 4,
preferably 2 or 3 carbon atoms. Specific examples include methyl
amine, dimethyl amine, trimethyl amine, ethyl amine, aniline,
N-methyl aniline, diphenyl amine, triphenyl amine, toluidine,
ethylene diamine, diethylene triamine.
[0037] Preferred .beta.-dicarbonyl compounds are those with 4 to
12, in particular 5 to 8 carbon atoms, e.g., diketones, such as
acetyl acetone, 2,3-hexanedione, 3,5-heptanedione, aceto-acetic
acid, aceto-acetic acid-C.sub.1-C.sub.4-alkyl ester, such as
aceto-acetic acid ethyl ester, diacetyl, and acetonyl acetone.
[0038] Examples of amino aides include .beta.-alanine, glycine,
valine, amino caproic acid, leucine and isoleucine.
[0039] Preferred silanes have at least one non-hydrolizable group
or a hydroxy group, and special preference goes to hydrolysable
organosilanes, which additionally have at least one
non-hydrolyzable residue. Preferred silanes have the general
formula (I)
R.sub.aSiX.sub.(4-a) (I)
wherein the residues R are the same or different, and represent
non-hydrolyzable groups, the residues X are the same or different,
and represent hydrolysable groups or hydroxy groups, and a has the
value 1, 2 or 3. The value for a is preferably 1.
[0040] In general formula (I), the hydrolysable groups X, which can
be the same or different, e.g., hydrogen or halogen (F, Cl, Br or
I), alkoxy (preferably C.sub.1-6-alkoxy, e.g., methoxy, ethoxy,
n-propoxy and butoxy), aryloxy (preferably C.sub.6-10-aryloxy,
e.g., phenoxy), acyloxy (preferably C.sub.1-6-acyloxy, e.g.,
acetoxy or propionyl oxy), alkyl carbonyl (preferably
C.sub.2-7-alkyl carbonyl, e.g., acetyl), amino, monoalkylamino or
dialkylamino with preferably 1 to 12, in particular 1 to 6 carbon
atoms. Preferred hydrolysable residues are halogen, alkoxy groups
and acyl oxy groups. Particularly preferred hydrolysable residues
are C.sub.1-4-alkoxy groups, in particular methoxy and ethoxy.
[0041] The non-hydrolysable residues R, which can be the same or
different, can be non-hydrolyzable residues R with or without a
functional group.
[0042] The non-hydrolyzable residue R without a functional group
can be alkyl (preferably C.sub.1-6-alkyl, such as methyl, ethyl,
n-propyl, isopropyl, n-butyl, sec.-butyl and tert.-butyl, pentyl,
hexyl, octyl or cyclohexyl), alkenyl (preferably C.sub.2-6-alkenyl,
e.g., vinyl, 1-propenyl, 2-propenyl and butenyl), alkinyl
(preferably C.sub.2-6-alkinyl, e.g., acetylenyl and propargyl),
aryl (preferably C.sub.6-10-aryl, e.g., phenyl and naphthyl) as
well as corresponding alkaryls and aralkyls (e.g., tolyl, benzyl
and phenethyl). The residues R and X can each have one or more
conventional substituents, as needed, e.g., halogen or alkoxy.
Alkyl trialkoxy silanes are preferred. Examples include:
[0043] CH.sub.3SiCl.sub.3, CHSi(OC.sub.2H.sub.5).sub.3,
CH.sub.3Si(OCH.sub.3).sub.3, C.sub.2H.sub.5SiCl.sub.3,
C.sub.2H.sub.5Si(OC.sub.2H.sub.5).sub.3,
C.sub.2H.sub.5Si(OCH.sub.3).sub.3,
C.sub.3H.sub.7Si(OC.sub.2H.sub.5).sub.3,
(C.sub.2H.sub.SO).sub.3SiC.sub.3H.sub.6Cl,
(CH.sub.3).sub.2SiCl.sub.2,
(CH.sub.3).sub.2Si(OC.sub.2H.sub.5).sub.2,
(CH.sub.3).sub.2Si(OH).sub.2, C.sub.6H.sub.5Si(OCH.sub.3).sub.3,
C.sub.6H.sub.5Si(OC.sub.2H.sub.5).sub.3,
C.sub.6H.sub.5CH.sub.2CH.sub.2Si(OCH.sub.3).sub.3,
(C.sub.6H.sub.5).sub.2SiCl.sub.2,
(C.sub.6H.sub.5).sub.2Si(OC.sub.2H.sub.5).sub.2,
(i-C.sub.3H.sub.7).sub.3SiOH, CH.sub.2.dbd.CHSi(OOCCH.sub.3).sub.3,
CH.sub.2.dbd.CHSiCl.sub.3,
CH.sub.2.dbd.CH--Si(OC.sub.2H.sub.5).sub.3,
CH.sub.2.dbd.CHSi(OC.sub.2H.sub.5).sub.3,
CH.sub.2.dbd.CH--Si(OC.sub.2H.sub.4OCH.sub.3).sub.3,
CH.sub.2.dbd.CH--CH.sub.2--Si(OC.sub.2H.sub.5).sub.3,
CH.sub.2.dbd.CH--CH.sub.2--Si(OC.sub.2H.sub.5).sub.3,
CH.sub.2.dbd.CH--CH.sub.2--Si(OOCCH.sub.3).sub.3,
n-C.sub.6H.sub.13--CH.sub.2--Ch.sub.2--Si(OC.sub.2H.sub.5).sub.3,
and
n-C.sub.8H.sub.17--CH.sub.2--CH.sub.2--Si(OC.sub.2H.sub.5).sub.3.
[0044] The non-hydrolyzable residue R with a functional group can
encompass a functional group in the form of an epoxide (e.g.,
glycidyl or glycidyloxy), hydroxy, ether, amino, monoalkyl amino,
dialkyl amino, if necessary, substituted anilino, amide, carboxy,
acryl, acryloxy, methacryl, methacryloxy, mercapto, cyano, alkoxy,
isocyanato, aldehyde, alkyl carbonyl, acid anhydride and phosphoric
acid group. These functional groups are bound to the silicon atom
via alkyklene, alkenylene or arylene bridge groups, which can be
interrupted by oxygen or NH groups. The bridge groups preferably
contain 1 to 18, preferably 1 to 8, and particularly 1 to 6 carbon
atoms.
[0045] The mentioned bivalent bridge groups and any present
substituents, as in the alkyl amino groups, are derived from the
aforementioned univalent alkyl, alkenyl, aryl, alkaryl or aralkyl
residues, for example. Naturally, the residue R can also encompass
more than one functional group.
[0046] Preferred examples for non-hydrolyzable residues R with
functional groups are a glycidyl or a
glycidyloxyl(C.sub.1-20)-alkylene residue, such as
.beta.-glycidyloxyethyl, .gamma.-glycidyloxypropyl,
.delta.-glycidyloxybutyl, .epsilon.-glycidyloxypentyl,
.omega.-glycidyloxyhexyl, and 2-(3,4-epoxycyclohexyl)ethyl, a
(meth)acryloxy-(C.sub.1-6)-alkylene residue, e.g., (meth)
acryloxymethyl, (meth)acryloxyethyl, (meth)acryloxypropyl or
(meth)acryloxybutyl, and a 3-isocyanatopropyl residue. Particularly
preferred residues are .gamma.-glycidyloxypropyl and
(meth)acryloxypropyl. ((Meth)acryl stands for methacryl or
acryl).
[0047] Specific examples for corresponding silanes include
.gamma.-glycidyloxypropyl trimethoxy silane (GPTS),
.gamma.-glycidyloxypropyl dimethyl chlorosilane, 3-aminopropyl
trimethoxy silane (APTS), 3-aminopropyl triethoxy silane (APTES),
N-(2-aminoethyl)-3-aminopropyl trimethoxy silane,
N-[N'-(2'-aminoethyl)-2-aminoethyl]-3-aminopropyl trimethoxy
silane, hydroxymethyl trimethoxy silane,
2-[methoxy(polyethylenoxy)propyl]trimethoxy silane,
bis-(hydroxyethyl)-3-amninopropyl triethoxy silane,
N-hydroxyethyl-N-methylaminopropyl triethoxy silane,
3-(meth)acrylooxypropyl triethoxy silane and 3-(meth)acryloxypropyl
trimethoxy silane.
[0048] Also possible is the use of silanes that at least partially
exhibit organic residues, which are substituted with fluorine. WO
92/217298 describes such silanes in detail. These can be
hydrolyzable silanes with at least one non-hydrolyzable residue
having the general formula
Rf(R).sub.bSiX.sub.(3-b) (II)
wherein X and R are as defined in formula (I), Rf is a
non-hydrolyzable group having 1 to 30 fluorine atoms bound to
carbon atoms, which are preferably separated from the Si by at
least two atoms, preferably an ethylene group, and b is 0, 1 or 2.
In particular, R is a residue without a functional group,
preferably an alkyl group such as methyl or ethyl. The groups Rf
preferably contain 3 to 25, an din particular 3 to 18, fluorine
atoms, which are bound to carbon atoms. Rf is preferably a
fluorinated alkyl group with 3 to 20 C atoms, with examples being
CF.sub.3CH.sub.2CH.sub.2, C.sub.2F.sub.5CH.sub.2CH.sub.2,
n-C.sub.6F.sub.13CH.sub.2CH.sub.2,
i-C.sub.3F.sub.7OCH.sub.2CH.sub.2CH.sub.2,
n-C.sub.8F.sub.17CH.sub.2CH.sub.2 and
n-C.sub.10F.sub.21--CH.sub.2CH.sub.2.
[0049] Examples for usable fluorosilanes include
CF.sub.3CH.sub.2CH.sub.2SiCl.sub.2(CH.sub.3),
CF.sub.3CH.sub.2CH.sub.2SiCl(CH.sub.3),
CF.sub.3CH.sub.2CH.sub.2Si(CH.sub.3) (OCH.sub.3) .sub.2,
C.sub.2F.sub.5CH.sub.2CH.sub.2--SiZ.sub.3,
n-C.sub.6F.sub.13CH.sub.2CH.sub.2SiZ.sub.3,
n-C.sub.8F.sub.17CH.sub.2CH.sub.2SiZ.sub.3,
n-C.sub.10F.sub.21--CH.sub.2CH.sub.2SiZ.sub.3 with
(Z.dbd.OCH.sub.3, OC.sub.2H.sub.5 or Cl),
i-C.sub.3F.sub.7OCH.sub.2CH.sub.2CH.sub.2SiCl.sub.2(CH.sub.3),
n-C.sub.6F.sub.13CH.sub.2CH.sub.2Si(OCH.sub.2CH.sub.3).sub.2,
n-C.sub.6F.sub.13CH.sub.2CH.sub.2SiCl.sub.2(CH.sub.3), and
n-C.sub.6F.sub.13CH.sub.2CH.sub.2SiCl(CH.sub.3).
[0050] The silanes can be manufactured according to known methods;
see W. Noll, "Chemistry and Technology of Silicones", Verlag Chemie
GmbH, Weinheim/Bargstra.beta.e (1968).
[0051] Examples for metal compounds that have a functional group
include metal compounds of a metal M from the primary groups III to
V and/or the secondary groups II to IV of the periodic table of
elements. Compounds of Al, Ti or Zr are preferred. Examples include
R.sub.GMX.sub.4-c (M=Ti or Zr and c=1, 2, 3), wherein X and R are
defined as above in formula (I), wherein one R or several R's in
conjunction can also stand for a complexing agent, e.g., a
.beta.-dicarbonyl compound or a (mono)carbonic acid. Zirconium and
titanium tetraalcoholates are here preferred, in which ha portion
of the alkoxy groups has been replaced by a complexing agent, e.g.,
a .beta.-dicarbonyl compound or a carbonic acid, preferably a
monocarbonic acid.
[0052] The substances used according to the invention can be mixed
together in any sequence desired. Mixing can take place directly in
the comminution machine, or beforehand in a separate container,
e.g., a mixer. Otherwise, no further additives are preferably
added, i.e., the mixture to be subjected to reactive comminution
consists of at least one dispersant, at least one modifying agent,
which can coincide with the dispersant in special instances, and
the particles, which preferably are particles consisting of only a
single material. Examples of additives that can be added as desired
include antifoaming agent, pressing aid, organic binders,
photocatalysts, preservatives and rheological additives. Additives
need only be supplied if required for further processing.
Therefore, these additives can also be supplied after processing
according to the invention. One advantage to prior addition may lie
in the homogeneous mixture obtained by milling.
[0053] During the execution of the method according to the
invention, the content of particles depends heavily on the type of
particle, but generally measures up to 60% v/v of the suspension,
normally ranging between 50 and 0.5% v/v, preferably between 30 and
1% v/v, in particular between 25 and 2.5% v/v of the dispersion.
The remaining suspension consists of dispersants and modifying
agents. The weight ratio between the particles and modifying agents
here generally measures 100:1 to 100:35, in particular 100:2 to
100:25, and especially preferred 100:4 to 100:20.
[0054] The quantity ratio of particles to milling elements present
in the milling chamber is inevitably derived from the solid content
of the suspension and the used fill level of milling balls and the
bulk density of the milling balls.
[0055] Mechanical comminution generally takes place in mills,
kneaders, cylinder mills or, for example, in high-velocity
dispersers. Suitable comminution machines for mechanical
comminution include homogenizers, turbo-agitators, mills with loose
milling implements, such as ball, rod, drum, cone, tube,
autogenous, planetary, vibration and agitating mills, heavy roller
kneader, mortar mills, colloid mills and cylinder mills.
Comminution, which can involve milling and homogenizing, preferably
takes place at room temperature. The duration depends on the type
of mixing, and the used comminution machine.
[0056] Mills with loose milling implements are preferably used. The
milling implements or milling bodies can be balls, rods or short
cylindrical pieces, for example. The container performs a rotating,
planetary or agitating motion, for example, or the milling bodies
are moved with an agitator.
[0057] Especially preferred mills are agitating ball mills with a
moving agitator and milling balls as the milling bodies.
[0058] Mills with very small milling bodies are preferably used,
which enables the application of small-dimensional shearing forces.
The finest dispersing step is preferably performed using milling
bodies having a diameter not exceeding 2.5 mm, preferably not
exceeding 1.5 mm, and especially preferred not exceeding 1.0 mm,
and measuring no less than 0.05 mm, preferably no less than 0.07
mm, and especially preferred no less than 0.09 mm. The milling
bodies normally consist of steel, plastic, hard metal, Al2O3,
agate, zirconium silicate, ZrO.sub.2, YZrO.sub.2, Ce--ZrO.sub.2,
glass, SiC, SiN or mixtures of these materials, wherein especially
preferred milling body materials are stabilized zirconium oxides,
zirconium silicate and steel.
[0059] Comminution can also take place in two or more stages. For
example, it can involve a preceding comminution (pre-comminution)
and subsequent finest comminution, wherein the modifying agents can
be present in each stage or in at least one stage, e.g., the last
one. For example, milling with milling bodies can be preceded by a
milling step with coarser milling bodies to achieve the optimal,
efficient initial particle size for the finest comminution
step.
[0060] The preferred particle size (average diameter or average
smallest dimension) for the finest comminution step measures 30 to
1,000 nm, preferably 50 to 500 nm, and especially preferred 60 to
150 nm.
[0061] Depending on the design of the used comminution machine, in
particular of a mill, fill levels of 50 to 100% are used for
milling bodies, for example, wherein fill levels preferably measure
60 to 98%, especially preferably 70 to 95%.
[0062] The comminution process in agitating ball mills takes place
at agitator speeds of 900 to 5,000 RPM, for example, with speeds of
1,000 to 4,500 RPM being preferred, and speeds of 2,000-4,200 RPM
being especially preferred.
[0063] The milling duration depends in particular on the type of
used particles, and can last several minutes up to days, e.g., 10
minutes to 5 days, preferably between 1 hour and 12 hours.
[0064] Reactive comminution can be supported through additional
energy supply (combined with the mechanical energy), e.g.,
microwave and/or ultrasound, wherein these two methods can also be
used simultaneously. It is especially preferred to supply energy to
the dispersion process directly in the comminution machine, but
this can also take place outside of the comminution machine in the
product circulation.
[0065] The method according to the invention is preferably carried
out at room temperature (approx. 20.degree. C.) up to the boiling
point of the dispersing medium. Suitable temperature moderation
(cooling) of the milling chamber of the mill makes it possible to
set these corresponding operating temperatures.
[0066] The method can be used both continuously in the single-pass
mode, multi-pass mode (oscillating process) or circular process, as
well as continuously in the batch mode.
[0067] Reactive comminution according to the invention chemically
binds the modifying agent to the comminuted particles. At least a
portion of the used modifying agent molecules are here bound to the
particles. The percentage that becomes chemically bound depends on
the type of particles, the used quantity in relation to the
particles, the obtained size, and hence the available particle
surface.
[0068] Combining the use of modifying agents and mechanical
comminution according to the invention makes it possible to
generate functional colloids that have chemical compounds rigidly
bound to the colloid particles. This enables the fabrication of
colloid particles of a smallest dimension extending even as far
down as 0.01 to 0.002 .mu.m.
[0069] The average smallest dimension (average diameter, average
height or width) of the particles manufactured in the method
according to the invention must not exceed 0.2 .mu.m, preferably
not exceed 0.1 .mu.m, and especially preferred not exceed 0.05
.mu.m. If needed, comminution can even yield particles with an
average smallest dimension not exceeding 0.01, and even one
exceeding 0.002 .mu.m.
[0070] The average smallest dimension the average particle diameter
for spherical particles, and the average height for plate-like
particles. In this description, average particle diameter is
understood to be the d.sub.50 value of volume distribution. The
expert is aware of methods for determining these particle sizes,
along with details relating to these methods. Examples for suitable
measuring procedures include dynamic laser light scattering (e.g.,
with an ultrafine particle analyzer (UPA)), X-ray disk centrifuging
or quantitative image analysis of electron microscopic
photographs.
[0071] If desired, functional colloid particles usable as powder
can be obtained from the resultant functional colloid by removing
the dispersant. Any method known to the expert can be used for
removal purposes, e.g., evaporation, centrifugation or filtration.
In another separation method, the expert uses known methods to set
the isoelectric point in order to obtain a flocculation that can
then be filtered out. The surface of the obtained functional
colloid particles has the chemically bound modifying agent
molecules, the functionality of which can be used to control the
particle properties. The colloid particles can then be absorbed
again in the same or another dispersant, wherein little or no
aggregation takes place, so that the average particle diameter can
essentially be retained.
[0072] The functional colloids or functional colloid particles can
be further processed via methods known to the expert. For example,
it can be reacted with other surface modifiers, dispersed in
organic or aqueous solvents, and soluble polymers, oligomers or
organic monomers or sols or additives, e.g., of the kind mentioned
above, can be added. Such mixtures, preparations or the functional
colloids or the very functional colloid particles according to the
invention can be used to manufacture coatings or in other
applications, for example.
[0073] Examples for the use of functional colloids, functional
colloid particles or mixtures encompassing these functional
colloids or functional colloid particles include the manufacture of
ceramic moldings, films, membranes and coatings, or of polymer
matrix compounds. The coatings or layers can be used for a wide
variety of purposes, e.g., coatings with low-energy surfaces or
abrasion-proof microbicides, photocatalytic, microstructurable or
microstructured, holographic, conductive, UV-absorbing,
photochromic and/or electrochromic layers.
[0074] The following examples serve to further illustrate this
invention.
EXAMPLES
[0075] Examples 1 to 5 were performed with a mill (Drais Perl Mill
PML-H/V). Specifications: Milling chamber gross volume: 1.2 l,
agitator, milling chamber cladding and milling body separation
(sieve cartridge) made of zirconium oxide, engine power main drive
4.0 kW, engine speed main drive 3,000 RPM, agitator speed 900-4,100
RPM.
Example 1
[0076] 600 ml of toluene, 50 g of talcum powder (<10 microns,
BET surface 14 m.sup.2/g) and 5 g of methyl trimethoxy silane are
placed in a reaction vessel and mixed for 30 minutes while
stirring. The obtained mixture is filled into an agitating ball
mill containing 1,300 g of milling balls (zirconium silicate, ball
diameter 0.6-1.0 mm). Milling takes place at 4,000 RPM for 4 hours.
The mill is then evacuated with 2 l of toluene. The solvent is
removed via centrifugation (4,000 RPM, 15 min). The remaining
powder is dried at 130.degree. C. for 24 hours in a vacuum drying
cabinet, and has a BET surface of 200 m.sup.2/g.
Example 2
[0077] 600 ml of toluene, 50 g of talcum powder (<10 microns,
BET surface 14 m.sup.2/g) and 7.2 g of phenyl trimethoxy silane are
placed in a reaction vessel and mixed for 30 minutes while
stirring. The obtained mixture is filled into an agitating ball
mill containing 1,300 g of milling balls (zirconium silicate, ball
diameter 0.6-1.0 mm). Milling takes place at 4,000 RPM for 4 hours.
The mill is then evacuated with 2 l of toluene. The solvent is
removed via centrifugation (4,000 RPM, 15 min). The remaining
powder is dried at 130.degree. C. for 24 hours in a vacuum drying
cabinet, and has a BET surface of 194 m.sup.2/g.
Example 3
[0078] 600 ml of toluene, 50 g of talcum powder (<10 microns,
BET surface 14 m.sup.2/g) and 8.9 g of methylacrylic
acid-3-trimethoxysilylpropyl ester] are placed in a reaction vessel
and mixed for 30 minutes while stirring. The obtained mixture is
filled into an agitating ball mill containing 1,300 g of milling
balls (zirconium silicate, ball diameter 0.6-1.0 mm). Milling takes
place at 4,000 RPM for 4 hours. The mill is then evacuated with 2 l
of toluene. The solvent is removed via centrifugation (4,000 RPM,
15 min). The remaining powder is dried at 130.degree. C. for 24
hours in a vacuum drying cabinet, and has a BET surface of 153
m.sup.2/g.
Example 4
[0079] 600 ml of toluene, 50 g of talcum powder (<10 microns,
BET surface 14 m.sup.2/g) and 5 g of 2-[methoxy(polyethyleneoxy)
propyl]trimethoxy silane are placed in a reaction vessel and mixed
for 30 minutes while stirring. The obtained mixture is filled into
an agitating ball mill containing 1,300 g of milling balls
(zirconium silicate, ball diameter 0.6-1.0 mm). Milling takes place
at 4,000 RPM for 4 hours. The mill is then evacuated with 2 l of
toluene. The solvent is removed via centrifugation (4,000 RPM, 15
min). The remaining powder is dried at 130.degree. C. for 24 hours
in a vacuum drying cabinet, and has a BET surface of 101
m.sup.2/g.
Comparative Example
[0080] 600 ml of toluene and 50 g of talcum powder (<10 microns,
BET surface 14 m.sup.2/g) are placed in a reaction vessel and mixed
for 30 minutes while stirring. The obtained mixture is filled into
an agitating ball mill containing 1,300 g of milling balls
(zirconium silicate, ball diameter 0.6-1.0 mm). Milling takes place
at 4,000 RPM for 4 hours. The mill is then evacuated with 2 l of
toluene. The solvent is removed via centrifugation (4,000 RPM, 15
min). The remaining powder is dried at 130.degree. C. for 24 hours
in a vacuum drying cabinet, and has a BET surface of 18
m.sup.2/g.
Example 5
[0081] 1,350 ml of toluene, 150 g of talcum powder (<10 microns,
BET surface 14 m.sup.2/g) and 15 g of methacrylic
acid[3-trimethoxysilyl propyl ester] are placed in a reaction
vessel and mixed for 30 minutes while stirring. The obtained
mixture is continuously pumped by an agitating ball mill (Netzsch
LabStar LS1) 90% filled with milling balls (zirconium oxide, ball
diameter 0.4 mm). Milling takes place at 3,000 RPM for 2 hours. The
mill is then evacuated with 2 l of toluene. The solvent is removed
via centrifugation (4,000 RPM, 15 min). The remaining powder is
dried at 130.degree. C. for 24 hours in a vacuum drying cabinet,
and has a BET surface of 180 m.sup.2/g.
Example 6
[0082] 1,000 ml of distilled water, 400 g of zirconium oxide (BET
surface 150.+-.10 m.sup.2/g) and 60 g of 3,6,9-trioxadecanic acid
are placed in a reaction vessel and mixed for 30 minutes while
stirring. The obtained mixture is milled in an agitating ball mill
for 4 hours (Drais Perl Mill PML-H/V, zirconium oxide milling
chamber cladding, milling chamber volume gross 1.2 l, 4,100 RPM,
1,700 g milling balls, zirconium silicate, ball diameter 0.3-0.4
mm, continuous operation in circular mode). The colloid obtained in
this way contains particles with an average particle diameter of
d.sub.50=0.0118 .mu.m (UPA).
Example 7
[0083] 880 ml of distilled water, 800 g of zirconium oxide (BET
surface 150.+-.10 m.sup.2/g) and 120 g of 3,6,9-trioxadecanic acid
are placed in a reaction vessel and mixed for 30 minutes while
stirring. The obtained mixture is milled in an agitating ball mill
for 4.5 hours (Drais Perl Mill PML-H/V, zirconium oxide milling
chamber cladding, milling chamber volume gross 1.2 l, 4,100 RPM,
1,700 g milling balls, zirconium silicate, ball diameter 0.3-0.4
mm, continuous operation in circular mode). The colloid obtained in
this way contains particles with an average particle diameter of
d.sub.50=0.0123 .mu.m (UPA).
Example 8
[0084] 150 ml of distilled water, 1,500 ml of i-propanol, 800 mg of
zirconium oxide (BET surface 150.+-.10 m.sup.2/g) and 40 g of
3,6,9-trioxadecanic acid and 38.6 g of methacrylic acid are placed
in a reaction vessel and mixed for 30 minutes while stirring. The
obtained mixture is milled in an agitating ball mill for 4.5 hours
(Drais Perl Mill PML-H/V, zirconium oxide milling chamber cladding,
milling chamber volume gross 1.2 l, 4,100 RPM, 1,700 g milling
balls, zirconium silicate, ball diameter 0.3-0.4 mm, continuous
operation in circular mode). The colloid obtained in this way
contains particles with an average particle diameter of
d.sub.50=0.0110 .mu.m (UPA).
Example 9
[0085] 800 ml of distilled water, 400 g of zirconium oxide
(Degussa, ZrO.sub.2-VP, BET surface 40.+-.10 m.sup.2/g (per
manufacturer), washed powder) and 60 g of 3,6,9-trioxadecanic acid
are placed in a reaction vessel and mixed for 30 minutes while
stirring. The obtained mixture is milled in an agitating ball mill
for 4.5 hours (Drais Perl Mill PML-H/V, zirconium oxide milling
chamber cladding, milling chamber volume gross 1.2 l, 4,100 RPM,
1,700 g milling balls, zirconium silicate, ball diameter 0.3-0.4
mm, continuous operation in circular mode). The colloid obtained in
this way contains particles with an average particle diameter of
d.sub.50=0.023 .mu.m (UPA), BET surface 75 m.sup.2/g.
Example 10
[0086] 800 ml of distilled water, 400 g of zirconium oxide (Tosoh,
ZrO.sub.2/TZ--O, BET surface 14 m.sup.2/g (per manufacturer)), and
60 g of 3,6,9-trioxadecanic acid are placed in a reaction vessel
and mixed for 30 minutes while stirring. The obtained mixture is
milled in an agitating ball mill (Drais Perl Mill PML-H/V,
zirconium oxide milling chamber cladding, milling chamber volume
gross 1.2 1, 4,100 RPM, 1,700 g milling balls, zirconium silicate,
ball diameter 0.3-0.4 mm, continuous operation in circular mode).
The colloid obtained in this way contains particles with an average
particle diameter of d.sub.5=0.073 .mu.m (UPA), BET surface 48
m.sup.2/g.
Example 11
[0087] 1,180 ml of distilled water, 800 g of aluminum oxide
(Sumitomo, AKP53, BET surface 9-15 m.sup.2/g (per manufacturer)),
and 60 g of 3,6,9-trioxadecanic acid are placed in a reaction
vessel and mixed for 14 hours while stirring. The obtained mixture
is milled in an agitating ball mill for 12 hours (Drais Perl Mill
PML-H/V, zirconium oxide milling chamber cladding, milling chamber
volume gross 1.2 1, 4,100 RPM, 1,700 g milling balls, zirconium
silicate, ball diameter 0.3-0.4 mm, continuous operation in
circular mode). 20 g of 3,6,9-trioxadecanic acid are added after 4
and 5.5 hours, respectively. The colloid obtained in this way has a
BET surface of 54 m.sup.2/g, d.sub.50=0.044 .mu.m (X-ray disk
centrifuge).
Example 12
[0088] 1,035 ml of ethanol, 201 g of titanium dioxide (Sachtleben,
Hombitec RM300, BET surface 60 m2/g (per manufacturer), washed
powder), 20.16 g of APTES and 4.8 ml of distilled water are placed
in a reaction vessel and mixed for 5 minutes while stirring. The
obtained mixture is milled in an agitating ball mill for 4 hours
(Drais Perl Mill PML-H/V, zirconium oxide milling chamber cladding,
milling chamber volume gross 1.2 l, 4,100 RPM, 1,700 g milling
balls, zirconium silicate, ball diameter 0.3-0.4 mm, continuous
operation in circular mode). Subsequent solvent replacement via
centrifugation and twofold washing with distilled water (pH=7)
yields a colloid with an average particle diameter of
d.sub.50=0.063 .mu.m (UPA), BET surface 99 m.sup.2/g, after
redispersion in water with pH 4.5.
* * * * *