Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Patent
1999-11-08
2000-10-24
Cain, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
528 35, 528 36, 528 37, C08G 7704
Patent
active
06136939&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to organosilane oligomers which are suitable as a coating composition.
DE 196 03 241 and WO 94/06807 disclose numerous cyclic organosilanes from which inorganic/organic hybrid systems may be produced by a sol/gel process. These materials may be used for coating surfaces. The resultant coatings are distinguished by elevated transparency, good solvent resistance and high resistance to mechanical wear combined with excellent resilience.
When coating porous substrates, for example porous inorganic particle or mineral surfaces (for example stone surfaces), the monomeric organosilanes penetrate deeply into the material and must accordingly be applied in an uneconomically large quantity, for example in multiple coats, in order to protect the surface effectively. Only once this is achieved are the coatings suitable, for example, as anti-graffiti coatings.
The object of the invention was to overcome these disadvantages. The coating materials to be developed to achieve this object should, however, be soluble in organic solvents so that they may be used at all.
This object is achieved with oligomers of certain cyclic organosilanes.
SUMMARY OF THE INVENTION
The present invention accordingly provides oligomers (I) soluble in organic solvents and obtainable by condensing identical or different monomers of the formula II ##STR2## in which m means 3 to 6, preferably 4, methyl or ethyl, 2 or 3, and
DETAILED DESCRIPTION OF THE INVENTION
Examples of compounds of the formula (II) are: ]}.sub.4, ]}.sub.4, ]}.sub.4, CH.sub.3 ]}.sub.4, ]}.sub.4.
Suitable organic solvents for the oligomers are, for example, mono- and polyfunctional alcohols, such as methanol, ethanol, n-butanol, ethylene glycol, as well as mixtures of aromatic hydrocarbons and aliphatic ketones or esters.
The oligomers (I) may be produced from the monomers of the formula (II) or directly from the starting products for the production of the monomers of the formula (II), wherein starting products which may be considered are those compounds of the formula (II) which contain a halogen atom, for example a chlorine, bromine or iodine atom, instead of the group OR.sub.2. The oligomers (I) are preferably produced using the corresponding chlorosilanes. The reaction proceeds in the presence of water and/or alcohol. The hydrogen chloride gas formed in this reaction is stripped or washed out, optionally in the presence of a base (for example NH.sub.3). In the event that the resultant oligomer mixture still contains Si--Cl groups, it may, for example, be post-treated with further base in the presence of water and/or alcohols.
The alcoholysis and hydrolysis of chlorosilanes are known in principle to the person skilled in the art.
Surprisingly, the oligomers I are soluble in the solvents and do not crosslink during the production thereof, despite having multifunctional reactive groups. In accordance with the process described, for example, in WO 94/06807 (sol/gel process), it is not possible to stop the polymerisation process so as to obtain soluble oligomers (I) which are stable in storage. Hydrolysis and condensation continue until an infusible and insoluble gel is obtained.
These oligomers are suitable not only for coating particles, in particular particles having inorganic constituents, preferably purely inorganic particles, but also for coating plastics in order to improve mechanical strength, as an anti-graffiti coating on mineral and metallic substrates or organic coatings (for example on buildings or vehicles) and for hydrophobising substrates, for example of stone or glass.
These oligomers are optionally used by (co-)condensation with alkoxides, for example those of the formula III, and/or nanoparticles (IV),
Examples of alkoxides of the formula III are:
Examples of nanoparticles (IV) are finely divided metal oxides or metal oxide hydroxides of the elements Si, Sn, In, Ti, Zr, B or Al, for example silica sols which in particular contain organic solvents. The preferred average particle size thereof, determined us
Mager Michael
Mechtel Markus
Bayer Aktiengesellschaft
Cain Edward J.
Gil Joseph C.
Roy Thomas W.
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