Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-10-19
2004-10-26
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C106S287160, C423S335000, C523S200000, C523S212000, C524S492000, C524S493000, C524S591000, C524S839000, C524S840000
Reexamination Certificate
active
06809149
ABSTRACT:
INTRODUCTION AND BACKGROUND
The present invention relates to functionalized silicas, a process for their preparation and their use.
It is known to react silicon dioxide obtained by flame hydrolysis and with a surface area of 40 to 200 m
2
/g with 3-methacryloxypropyltrimethoxysilane. The resulting silicon dioxide is then coated with a further shell of (meth)acrylate polymers and subsequently employed in dental compositions (EP 0 142 784 A1).
SUMMARY OF THE INVENTION
The present invention provides functionalized silicas, characterized by functional groups fixed on the surface, the groups being 3-methacryloxypropylsilyl and/or glycidyloxypropylsilyl.
The present invention also provides a process for the preparation of the functionalized silicas, which is characterized in that a silica is sprayed optionally first with water or dilute acid and then with a surface modification reagent or a mixture of several surface modification reagents in a suitable mixing vessel, with intensive mixing, the components are optionally re-mixed for 15 to 30 minutes and heat-treated at a temperature of 100 to 400° C. over a period of 1 to 6 h.
A silica prepared pyrogenically by the route of flame hydrolysis of SiCl
4
can preferably be employed as the silica. Such pyrogenic silicas are known from Ullmanns Enzyklopädie der technischen Chemie [Ullmanns Encyclopaedia of Industrial Chemistry], 4th edition, volume 21, page 464 (1982).
In a preferred embodiment of the invention, a pyrogenic silica with a surface area of approx. 200 m
2
/g can be employed (Aerosil® 200).
Monomeric substances, such as 3-methacryloxypropyltrialkoxysilane and/or glycidyloxypropyltrialkoxysilane, wherein alkoxy can be methoxy, ethoxy and/or propoxy, can be employed as the surface modification reagent.
The amount of silane can be metered with respect to the silica such that no or only a small excess results. The excess silane can optionally be removed during the heat treatment.
The silica according to the invention can be employed in solvent-containing coatings, for example 2-component polyurethane coatings.
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European Office Action dated May 4, 2001.
Matsumura, Kazuyuki et al., “Surface Treatment of Silica”.
Patent Abstract of Japan, Publication No. 10-204319, Publication Date: Apr. 4, 1998.
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Ettlinger Manfred
Frahn Stephanie
Kerner Dieter
Meyer Jürgen
Degussa - AG
Niland Patrick D.
Smith Gambrell & Russell
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