Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2002-03-29
2004-03-02
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S402000, C428S402240, C428S403000, C428S404000, C428S405000, C428S407000, C428S409000, C428S448000, C428S413000, C428S423100, C428S480000, C428S523000, C523S205000, C523S206000, C523S209000, C523S223000, C523S400000, C524S500000, C524S502000, C524S506000, C524S507000, C524S863000, C427S212000, C427S215000, C427S387000
Reexamination Certificate
active
06699586
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition comprising organosilicon nanohybrid and/or microhybrid capsules for scratch and abrasion resistant coatings. The present invention further relates to the use of such compositions as coating materials for producing a scratch and abrasion resistant coatings on substrates and particles.
2. Discussion of the Background
It is known that the surface properties of sol or gel particles of metal or of semi-metal oxides can be modified by treatment with a hydrolyzable organosilane or organosiloxane, where generally only a single silane layer attaches to the oxide or sol gel particle. Oxides and sol or gel particles thus treated, such as inorganic pigments or fillers, can be introduced into a polymer matrix, particularly into films and also into coating compositions and coatings which can be produced from them. In general, however, the scratch and abrasion resistance of such polymer systems is poor.
DE 198 46 660 discloses nanoscale, surface-modified oxide and mixed oxide particles which are enveloped by organosilicon groups bonded covalently to the oxide particle, the organofunctional groups being described as reactive groups and usually having an outward orientation, so that they are incorporated into the polymer matrix by polymerization with the polymer material when the prepolymer cures. The process for preparing such coating compositions is cumbersome, since the organosilane and the oxide component are incorporated into the prepolymer in alternation.
DE 198 46 659 dates from the same time as DE 198 46 660 and relates to a layer material provided with a scratch resistant synthetic resin layer which likewise comprises nanoscale, surface-modified oxide particles.
DE 198 46 659 teaches specifically the use of acryloyloxyalkylsilanes for producing a shell around nanoscale oxide particles, which possesses reactive, radiation-crosslinkable groups. Here again, the coating material is prepared by a time-consuming reaction of a nanoscale silica with 3-methacryloyloxypropyltrimethoxysilane (DYNASYLAN® MEMO) in an acrylate formulation in the presence of water, an acid, and a wetting agent. Again, the components have to be combined in alternation in a specific sequence.
In many cases, said coating materials are of high viscosity and usually contain only a small fraction of oxide particles, which affects the scratch resistance of the subsequent coating. It is also difficult to apply such high viscosity coating materials to a substrate, especially when the substrate in question is thin and liable to tear. The scratch and abrasion resistance of coatings obtainable in this way is often in need of improvement. With such high-viscosity systems furthermore, a special and complex application device is required. In many cases, as well, solvents are added to such high-viscosity coating materials, and lead to an increase in the organic emissions (VOC problems; VOC=volatile organic compounds).
Coatings which are substantially scratch resistant (DIN 53799) can be produced in accordance with the teaching of the as yet unpublished German patent applications 101 00 631.4 and 101 00 633.0. Unfortunately, such coating systems cannot be used for applications where there is a requirement not only for scratch resistance but also for good abrasion resistance (haze to DIN 52 347/ASTM D-1044 and abrasion to DIN 68 861), such as for wood coatings, polymer flooring and wood block flooring.
A commercially customary abrasion resistant PU (polyurethane) varnish gives 2 mg of abraded material after 50 turns (Taber Abraser test to DIN 68 861).
SUMMARY OF THE INVENTION
The object was therefore to provide a possibility for maximizing the scratch and abrasion resistance properties of resin-based coatings. This object is achieved in accordance with the invention as specified in the claims.
Systems have been found based on organosilicon microhybrid capsules (also referred to below as microhybrid systems) or organosilicon nanohybrid and microhybrid capsules together, present another (also referred to below as organosilicon nano/microhybrid systems) composed of oxide particles (KA—O) comprising (a) a nanoscale oxide and/or mixed oxide as nanoscale cores and/or (b) a micro scale synthetic corundum, especially PLAKOR® 13 (ESK-SIC GmbH, average particle diameter 13 &mgr;m), as micro scale cores and, in each case, an organosilicon or polymerizable organosilicon shell B, said organosilicon shell B comprising at least one organosilicon constituent of the general formula Ia
(Si′O—)
x
Si—R (Ia)
in which the groups R are identical or different and R is an organofunctional group, such as alkyl, e.g. methyl, propyl, butyl, octyl, perfluoroalkyl, tridecafluoro-1,1,2,2-tetrahydrooctyl, or alkenyl, such as vinyl or allyl, or aryl, such as phenyl or benzyl, or aminoalkyl, such as 3-aminopropyl, N-(2-aminoethyl)-3-amino propyl, N′-(2-aminoethyl)-N-(2-aminoethyl)-3-aminopropyl, glycidyloxyalkyl, such as 3-glycidyloxypropyl, or methacryloyloxyalkyl, such as 3-methacryloyloxypropyl, to give but a few examples, and x is a number from 0 to 20, the remaining free valences of Si being satisfied by SiO— and/or —Z and the free valences Si′ being satisfied by SiO—, —R and/or —Z, the groups Z are identical or different and are hydroxyl and/or alkoxy radicals, such as methoxy, ethoxy, propoxy or butoxy, and each Si and Si′ of the shell B carries not more than one group R,
and/or the organosilicon constituent of the shell B being attached via one or more covalent linkages of the general formula Ib
(KA—O)—[(Si′O—)
x
Si—R] (Ib)
in which the groups R are identical or different and R is as defined above and x is a number from 1 to 20, the remaining free valences of Si being satisfied by (KA—O)—, SiO— and/or —Z and the free valences of Si′ being satisfied by (KA—O)—, SiO—, —R and/or —Z, the groups Z are identical or different and are hydroxyl and/or alkoxy radicals, and each Si and Si′ of the shell Et carries not more than one group R,
to the core A (KA—O).
It has also been found that said organosilicon nano/microhybrid systems or microhybrid systems are obtained in a simple and economical manner in a composition based on a curable synthetic resin or precursor compound of a curable synthetic resin, directly in the course of its preparation, and that a corresponding composition can be used as the basis for a coating material which, following application to a substrate or an article and subsequent curing, leads to outstanding scratch and abrasion resistance.
By a curable synthetic resin or a precursor of a curable synthetic resin, i.e., a liquid prepolymer or a mixture of such prepolymers, is meant hereinbelow, for example, acrylates, methacrylates, epoxy, polyurethane, unsaturated polyesters or mixtures thereof.
Furthermore, the present process produces oxide particles with a substantially complete and multilayer organosilicon shell, i.e., cores A which, directly and advantageously, are obtained in finely dispersed form in a curable synthetic resin or precursor of a curable synthetic resin.
In the present procedure, the product is generally the organosilicon microhybrid system or organosilicon nano/microhybrid system of the invention simultaneously incorporated homogeneously into the prepolymer.
Compositions obtained in this way are distinguished by surprisingly advantageous processing properties on preparation and application, since practice shows that, despite the corundum fraction in the composition, the organosilicon envelopment of the corundum particles means that no additional wear is found on the mixing and application equipment.
Dilatancy in paints can be a problem in technical processes generally and especially in the case of coatings made with the specialty paints. In general, the aim with such coating systems is for a viscosity of up to 2500 mPa s. Preferably, solvent-free coating materials of the invention possess a viscosity of >500 to 2000 mPa s, with particular pr
Edelmann Roland
Gläsel Hans-Jürgen
Langguth Helmut
Mehnert Reiner
Monkiewicz Jaroslaw
Dawson Robert
Degussa - AG
Feely Michael J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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