Aqueous creams of organosilicon compounds

Details Aqueous creams of organosilicon compounds Aqueous creams of organosilicon compounds

2001-07-19

2002-12-10

Dawson, Robert (Department: 1712)

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...

C524S588000, C524S837000, C523S335000, C516S055000, C106S287110, C106S287160, C052S515000, C052S517000

Reexamination Certificate

active

06492459

ABSTRACT:

The invention relates to an aqueous firm cream and a process for impregnating or priming mineral building materials to impact water-repellency.
Organosilicon compounds are used in building protection especially owing to their outstanding impregnation effect for protection from water and dirt. Siliconates, silicone resins, monomeric silanes and oligomeric silanes have been established for years for this application. The active ingredients are usually dissolved or dispersed in low-viscosity carrier media, such as, for example, organic solvents or water. Low-viscosity active ingredients, such as, for example, monomeric silanes or low-viscosity mixtures of silanes and siloxanes, can also be applied undiluted to the building material.
A disadvantage of these impregnating compositions is that they readily run off or drip off vertical surfaces and very particularly during overhead work.
Silane-, siloxane- or silicone resin-based compositions containing mineral thickeners can on the other hand also be applied as a relatively thick layer to the building materials, without running off. The organosilicon compound penetrates into the building material and the thickener remains behind. U.S. Pat. No. 4,076,868 describes, for example, solutions of methylpolysiloxane in toluene which are thickened with silica. WO 95/25706 describes a process for imparting water-repellency with solvent-free silane/siloxane mixtures thickened with bentonites. The disadvantage of these processes is that the mineral thickener remains behind on the building material and has to be removed and disposed of.
In EP-A-819 665, these disadvantages are counteracted by using so-called water-repellent creams. These are aqueous, firm products based on organosilicon compounds, which are free of solids and organic solvents. The active ingredient content of these creams is preferably 60 to 95%.
On absorptive building materials, such as, for example, bricks, concrete, sand-lime bricks, fibre cement boards, mineral renders and many natural stones, impregnating compositions whose active ingredient content is frequently in the range of 5-25% are generally applied. For these applications, the active ingredient concentration of the water-repellent creams described in EP-A-819 665 is too high.
It was the object of the present invention to provide water-repellent creams whose application includes all advantages of the water-repellent creams of EP-A819 665 but whose active ingredient content can additionally be adjusted as desired.
The invention relates to an aqueous, firm cream which contains the components
(A) which are selected from
(A1) C
1
-C
20
-alkyl-C
2
-C
6
-alkoxysilanes and
(A2) organopolysiloxane containing alkoxy groups,
(C) emulsifier and
(D) organic solvent.
In a preferred embodiment, the aqueous cream additionally contains a component (B) which contains aminoalkyl groups and is selected from alkoxysilane (B1) containing aminoalkyl groups or organopolysiloxane (B2) which, in addition to other organosiloxane units, contains those siloxane units which have radicals bonded via SiC and having basic nitrogen, with the proviso that the amine number of the organopolysiloxane (B2) is at least 0.01.
Pasty, water-containing formulations which are emulsion systems comprising water-immiscible oil phase, namely active ingredients (A) and optionally (B) plus organic solvents (D), water and emulsifiers (C), are designated as cream. The cream is considered to be firm if it can be applied by means of a doctor blade or brush or by spraying in a coat thickness of at least 0.5 mm to vertical absorptive mineral building materials, such as, for example, sand-lime brick or clay brick, and, after application, does not run down more than 1 cm before it has been completely absorbed by the building material.
Preferably, the C
1
-C
20
-alkyl-C
2
-C
6
-alkoxysilanes (A1) have 1 or 2 identical or different, optionally halogen-substituted monovalent C
1
-C
20
-alkyl radicals bonded via SiC, and the remaining radicals are identical or different C
2
-C
6
-alkoxy radicals. Methoxysilanes undergo hydrolysis too rapidly and prevent a sufficient shelf life.
Examples of the C
1
-C
20
-alkyl radicals are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl and tert-pentyl radicals; hexyl radicals, such as the n-hexyl radical; heptyl radicals, such as the n-heptyl radical; octyl radicals, such as the n-octyl radical, and isooctyl radicals, such as the 2,2,4-trimethylpentyl radical; nonyl radicals, such as the n-nonyl radical; decyl radicals, such as the n-decyl radical and dodecyl radicals, such as the n-dodecyl radical; cycloalkyl radicals, such as cyclopentyl, cyclohexyl, 4-ethylcyclohexyl and cycloheptyl radicals, norbornyl radicals and methylcyclohexyl radicals.
Examples of halogen-substituted C
1
-C
20
-alkyl radicals are alkyl radicals substituted by fluorine, chlorine, bromine and iodine atoms, such as the 3,3,3-trifluoro n-propyl radical, the 2,2,2,2′,2′,2′-hexafluoroiso-propyl radical and the heptafluoroisopropyl radical.
The unsubstituted C
1
-C
12
-alkyl radicals are particularly preferred.
Examples of C
2
-C
6
-alkoxy radicals are the ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy and tert-butoxy radicals; pentyloxy radicals, such as the n-pentyloxy radical, and hexyloxy radicals, such as the n-hexyloxy radical. The ethoxy radicals are particularly preferred.
The alkoxy radicals may be substituted by halogen atoms, but this is not preferred.
The aqueous cream may contain an organopolysiloxane (A2) containing alkoxy groups, or a mixture of several organopolysiloxanes. The organopolysiloxanes may additionally contain hydroxyl groups, which facilitate binding to the building materials.
The organopolysiloxanes (A2) preferably have a viscosity of not more than 2000 MPa.s, in order to achieve a particularly good distribution on the pore surfaces in the masonry. It is also possible to use organopolysiloxanes having a higher viscosity, including solid resins, e.g. solid methylsilicone resins having a molecular weight of 2000 to 10,000 g/mol with, for example, a glass transition temperature range of 40-50° C., or solid resins comprising R
3
SiO
0.5
and SiO
2
units (MQ resins) having a preferred ratio of R
3
SiO
0.5
to SiO
2
of 0.4:1 to 1.2:1. These are preferably present in solution in silanes (A1) or in low-viscosity organopolysiloxanes (A2) or in the organic solvent (D).
The organopolysiloxanes (A2) comprising units of the general formula (I)
R
x
⁢
Si
⁡
(
OR
1
)
y
⁢
Si
⁡
(
OH
)
z
⁢
O
4
-
x
-
y
-
z
2
(
I
)
in which
R denote identical or different monovalent, optionally halogen-substituted C
1
-C
20
-hydrocarbon radicals bonded via SiC,
R
1
denote identical or different monovalent C
1
-C
6
alkyl radicals,
x denotes 0, 1, 2 or 3, on average 0.8 to 1.8,
y denotes 0, 1, 2 or 3, on average 0.01 to 2.0, and
z denotes 0, 1, 2 or 3, on average 0.0 to 0.5, with the proviso that the sum of x, y and z is not more than 3.5, are particularly suitable.
Examples of the C
1
-C
20
-hydrocarbon radicals are the C
1
-C
20
-alkyl radicals and halogen-substituted C
1
-C
20
-alkyl radicals mentioned above in the case of the organoalkoxysilanes (A1), the alkenyl radicals, such as the vinyl, allyl, n-5-hexenyl, 4-vinylcyclohexyl and 3-norbornenyl radicals; aryl radicals, such as the phenyl, biphenylyl, naphthyl, anthryl and phenanthryl radicals; alkaryl radicals, such as o-, m- and p-tolyl radicals, xylyl radicals and ethylpheyl radicals; aralkyl radicals, such as the benzyl radical, the alpha- and the &bgr;-phenylethyl radical. The unsubstituted C
1
-C
12
-alkyl radicals and the phenyl radical are particularly preferred.
Although not indicated in the abovementioned formula, some of the radicals R can be replaced by hydrogen atoms bonded directly to silicon atoms. However, this is not preferred.
Examples of the radicals R
1
are the methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and tert-butyl radicals; pentyl radicals, such as the n-pentyl radical, and hexyl radicals, such

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