Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-03-20
2003-11-18
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S200000, C523S205000, C523S216000, C525S327300, C525S533000, C528S112000
Reexamination Certificate
active
06649672
ABSTRACT:
The invention relates to binders modified with nanoparticles for lacquer systems, to coating compositions containing them and to the use thereof.
Lacquer systems containing nanoparticles are state of the art. The nanoparticles lead to an improved properties profile of the lacquer systems, for example in respect of scratch resistance and resistance to solvents and chemicals. For example, EP-A-0 832 947 describes scratch-resistant clear lacquers based on a binder/crosslinking agent system and nanoparticles having reactive groups at the particle surface. Furthermore, EP-A-0 872 500 describes scratch-resistant coating compositions based on a combination of hydroxy-functional binders with nanoparticles having blocked isocyanate groups at the particle surface. When the coating layers applied from such coating compositions are cured, the nanoparticles are bonded chemically into the coating layer.
Compatibility problems can occur when nanoparticles are incorporated into lacquer systems. For example, in the case of lacquer systems of the prior art containing nanoparticles, inhomogeneous distribution of the nanoparticles in the coating layers applied from such coating compositions is from time to time obtained, or homogeneous distribution of the nanoparticles in the coating compositions as such is difficult, if not completely impossible, from the outset.
The object is to eliminate or largely avoid such compatibility problems in lacquer systems containing nanoparticles.
The object can be achieved by reaction of carboxyl-functional nanoparticles with epoxy-functional binders to give lacquer binders modified with nanoparticles.
The invention accordingly provides binders modified with nanoparticles, which binders are prepared by reacting carboxyl-functional nanoparticles with epoxy-functional binders.
The nanoparticles are conventional particles known to the person skilled in the art having a size in the “nanometer” range, for example having a mean particle size of from 5 to 200 nm, preferably from 10 to 100 nm, which contain carboxyl groups especially at the particle surface. The nanoparticles may be of single-phase structure or have a core/shell structure. Nanoparticles of single-phase structure contain carboxyl groups, especially at the particle surface. In the case of nanoparticles composed of a core and a shell, the carboxyl groups are a constituent of the shell and, optionally, additionally of the core. The acid number of the carboxyl-functional nanoparticles is, for example, from 20 to 200 mg KOH/g. In addition to the carboxyl groups, the nanoparticles may also contain further functional groups that do not interfere with an epoxy/carboxy reaction.
The nanoparticles of single-phase structure are inorganic in nature and have been modified by carboxyl groups and, optionally, further organic radicals. For example, they are element-oxygen networks containing elements from the group aluminium, boron, titanium, zirconium and/or silicon, preferably silicon.
The nanoparticles of single-phase structure are preferably particulate organoaluminium, organoboron, organotitanium, organozirconium and/or organosilicon, particularly preferably organosilicon, polymers (Ia) of the formula (R
3
SiO
1/2
)
w
(R
2
SiO
2/2
)
x
(RSiO
3/2
)
y
(SiO
4/2
)
z
, wherein y=from 10 to 100 mol. % and the sum of w, x, y and z is to be 100 mol. %. The radicals R, which may be identical or different, may be, in addition to carboxyl-group-containing radicals, C
1
-C
6
-alkyl radicals, especially methyl radicals, alkenyl radicals, such as, for example, vinyl and allyl radicals, aryl radicals, such as, for example, a phenyl radical, or substituted hydrocarbon radicals, such as, for example, mercaptoalkyl, cyanoalkyl, aminoalkyl, acyloxyalkyl, such as 3-(meth)acryloyloxypropyl, and hydroxyalkyl radicals. The carboxyl groups may have been produced, for example, by suitable reaction of suitable radicals R, for example by saponification of cyanoalkyl radicals or by oxidation of suitable radicals R. The carboxyl groups may also be introduced directly during the preparation of the organosilicon polymers (Ia).
The preparation of such organosilicon polymers (Ia) can be carried out, for example, according to a single-step emulsion polymerisation process, for example by adding a monomeric silane RSi(OR′)
3
or a mixture of monomeric silanes of the type R
a
Si(OR′)
4−a
, wherein a=0, 1, 2 or 3, to an agitated emulsifier/water mixture. A two-step procedure for the emulsion polymerisation process is also possible, wherein the silanes reacted in the first process step preferably have no carboxyl-group-containing radicals R and the reaction of silanes having carboxyl-group-containing radicals R does not take place until the second process step. R is as defined above. R′ represents C
1
-C
6
-alkyl radicals, aryl radicals or substituted hydrocarbon radicals. The principle of and details relating to the implementation of such emulsion polymerisation processes are known to the person skilled in the art, for example from EP-A-0 492 376.
In the case of nanoparticles composed of a core and a shell, the core is of inorganic nature and has optionally been modified by further organic radicals. For example, they are element-oxygen networks containing elements from the group aluminium, boron, titanium, zirconium and/or silicon, preferably silicon.
The cores may also be colloidal metallic oxides, with preference being given to colloidal silicon dioxide known to the person skilled in the art, for example in the form of a powder or in the form of a dispersion in an aqueous or other organic solvent.
The cores of nanoparticles composed of a core and a shell are preferably organoaluminium, organoboron, organotitanium, organozirconium and/or organosilicon, particularly preferably organosilicon, polymers (Ib) of the formula (R″
3
SiO
1/2
)
w
(R″
2
SiO
2/2
)
x
(R″SiO
3/2
)
y
(SiO
4/2
)
z
, wherein y=from 10 to 100 mol. % and the sum of w, x, y and z is to be 100 mol. %. The radicals R″, which may be identical or different, may be carboxyl-group-containing radicals, C
1
-C
6
-alkyl radicals, especially methyl radicals, alkenyl radicals, such as, for example, vinyl and allyl radicals, aryl radicals, such as, for example, a phenyl radical, or substituted hydrocarbon radicals, such as, for example, mercaptoalkyl, cyanoalkyl, aminoalkyl, acyloxyalkyl, such as 3-(meth)acryloyloxypropyl, and hydroxyalkyl radicals. The carboxyl groups may have been produced, for example, by suitable reaction of suitable radicals R″, for example by saponification of cyanoalkyl radicals or by oxidation of suitable radicals R″. The carboxyl groups may also be introduced directly during the preparation of the organosilicon polymers (Ib).
The preparation of such organosilicon polymers (Ib) can be carried out, for example, according to the emulsion polymerisation process, for example by adding a monomeric silane R″Si(OR′)
3
or a mixture of monomeric silanes of the type R″
a
Si(OR′)
4−a
, wherein a=0, 1, 2 or 3, to an agitated emulsifier/water mixture. R″ is as defined above. R′ represents C
1
-C
6
-alkyl radicals, aryl radicals or substituted hydrocarbon radicals. The principle of and details relating to the implementation of such emulsion polymerisation processes are known to the person skilled in the art, for example from EP-A-0 492 376.
In the case of nanoparticles composed of a core and a shell, the cores, for example of type (Ib), are preferably surrounded by a carboxyl-functional (meth)acrylic copolymer. For the preparation of nanoparticles composed of a core and a carboxyl-functional (meth)acrylic copolymer shell, (meth)acrylically unsaturated monomers are subjected to radical polymerisation, for example to emulsion polymerisation, in the presence of the cores, for example in the sense of a graft polymerisation on to the cores. For the introduction of the carboxyl groups into the (meth)acrylic copolymer shell, there are employed or used concomitantly in
Dücoffre Volker
Flosbach Carmen
Tännert Klaus
Weidenhammer Petra
Aylward D.
Dawson Robert
E. I. du Pont de Nemours and Company
Fricke Hilmar L.
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