Ink, paint, pollutant, bioorganism, oil, water and/or dirt...

Details Ink, paint, pollutant, bioorganism, oil, water and/or dirt... Ink, paint, pollutant, bioorganism, oil, water and/or dirt...

2001-09-27

2003-11-04

Beck, Shrive P. (Department: 1762)

Coating processes

Applying superposed diverse coating or coating a coated base

Synthetic resin coating

C427S421100, C427S428010, C427S429000, C427S430100, C428S447000, C106S287110, C106S287120, C106S287130, C528S038000

Reexamination Certificate

active

06641870

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink, paint, pollutant, bioorganism, oil, water and/or dirt repellent coating on an absorbent inorganic substrate and to a process for producing such a coating, including substrates thus coated.
2. Discussion of the Background
The preparation of alkylalkoxysilanes and also fluoroalkylalkoxysilanes or corresponding polycondensates has long been known, as has their use substantially as hydrophobicizing and oleophobicizing agents (DE-A 15 18 531, EP 0 101 816 B1, EP 0 587 667 B1, EP 0 716 127 A2, EP 0 716 128 A2 and DE-A 195 44 763).
In order to obtain sufficiently stable solutions and formulations of alkyl-functional and/or fluoroalkylfunctional silanes, and of corresponding cocondensates, organic solvents or else emulsifiers have been used (DE C 27 51 714, EP 0 538 555 B1, EP 0 819 665 A1, WO 95/23830, EP 0 846 716 A1, EP 0 960 921 A1).
Nitrogen-containing or aminoalkyl-functional and fluoroalkyl-functional, and substantially alkoxy-free, organosiloxanes are known as water-soluble constituents in otherwise emulsifier- and surfactant-free compositions for producing surfaces which repel water, oil and dirt (EP 0 846 717 A1).
The German patent application 199 55 047.6 discloses a composition which comprises at least one triaminoalkyl and fluoroalkyl-functional, hydroxyl- and/or alkoxy-containing organosiloxane or a corresponding organosiloxane mixture, water, with or without an alcohol component and with or without an acid component, the composition being suitable for use in particular for hydrophobicizing and/or oleophobicizing surfaces, for anti-graffiti applications, i.e., with an ink and paint repelling action, and for easy to clean applications, i.e., with a dirt or bioorganism repelling activity.
Daubing on buildings, especially in larger cities, is an ever increasing problem worldwide. The cleaning of affected facades is very laborious and entails high costs. Accordingly, what are known as anti-graffiti protective coats are applied to regions of the facade that are at risk.
DE 199 55 047.6 reveals that water-based co-condensates of triamino-functional trialkoxysilanes and fluoroalkylsilanes are particularly suitable for graffiti protection. At the same time, however, these products are very expensive, since the starting materials used to prepare them carry high prices. Absorbent, i.e., porous mineral building materials, such as concrete, may require the use of fairly large amounts when impregnated with the substances described in DE 199 55 047.6, which in many cases may prove prohibitive—primarily for reasons of cost—to their use.
Concrete and other mineral building materials are at risk not only from graffiti daubing but also from penetrating water, which may carry pollutants, such as chlorides, into the porous structure and may, for example, damage the steel reinforcement of concrete. Because of their very low depth of penetration, the abovementioned fluoro-functional co-condensates of DE 199 55 047.6 afford hardly any protection against penetrating chlorides.
There is therefore a need for anti-graffiti coatings which necessitate the use of very small amounts of high-priced products while at the same time affording enhanced protection against water-transported pollutants.
It is an object of the invention to provide a further possibility for protecting inorganic substrates, and, in particular, for furnishing them with anti-graffiti properties.
SUMMARY OF THE INVENTION
According to one embodiment of the present invention is a method of producing a coating on a substrate by applying at least two coatings of an organosiloxane.
According to another embodiment of the present invention is a method of producing a coating on a substrate comprising applying at least two coatings of an organosiloxane in which a concentration of organosiloxane in a first coating step is less than a concentration of organosiloxane in a second coating step.
According to another embodiment of the present invention is a method of producing a coating on a substrate comprising applying an alkyl-functional alkyltrialkoxysilane followed by applying an organosiloxane.
These and other objects of the present invention have been made possible by first applying a highly diluted solution of an organosiloxane such as those described in DE 199 55 047.6, endowing the surface with a water repelling effect, and then appropriately applying one or more further coats of an organosiloxane such as those products described in DE 199 55 047.6. It has been surprisingly found that anti-graffiti coatings with reduced consumption of material may be prepared by such a method.
These and other objects of the present invention have also been made possible by first applying at least one alkyl-functional trialkoxysilane followed by treatment with an organosioxane. It has also surprisingly been found that the penetration of water and thus the penetration of water-dissolved pollutants into mineral substrates, in combination with an outstanding anti-graffiti effect, can be achieved by subjecting said substrates, prior to coating them one or more times with an organosiloxane such as the products described in DE 199 55 047.6, to treatment with at least one alkyl-functional alkyltrialkoxysilane.
In accordance with the process of the invention, it is possible advantageously to produce a permanent anti-graffiti coating with outstanding ink, paint, pollutant, bioorganism, oil, water, and dirt repelling properties.
The present invention accordingly provides a process for producing an ink, paint, pollutant, bioorganism, oil, water and/or dirt repellent coat on an inorganic substrate, which comprises:
A) applying to a substrate in a first step a composition comprising an organosiloxane selected from the group consisting of
(i) an organosiloxane which carries at least one triamino group of the general formula I
[NH
x
(CH
2
)
a
NH
y
(CH
2
)
b
NH
z
]—  (I),
such a group being attached by way of at least one N-bonded alkylene group having 1 to 4 carbon atoms to at least one silicon atom, a and b being identical or different and representing an integer from 1 to 6, x being 0 or 1 or 2, y being 0 or 1, z being 0 or 1 or 2, subject to the proviso that (x+y+z)≦4,
at least one Si—C-bonded fluoroalkyl group of the general formula II
F
3
C(CF
2
)
r
(CH
2
)
s
—  (II)
in which r is an integer from 0 to 18 and s is 0 or 2, and at least one hydroxyl and/or alkoxy group,
(ii) a formulation which comprises an organosiloxane or a mixture of organosiloxanes as per (i),
(iii) an alkylalkoxysilane in which alkyl represents linear, branched or cyclic alkyl radicals having 1 to 16 carbon atoms and alkoxy represents methoxy or ethoxy or propoxy or butoxy,
(iv) a formulation which comprises at least one organosiloxane which carries at least one amino group of the general formula III
[NH
2
(CH
2
)
a
(NH)
r
(CH
2
)
b
(NH)
s
]—  (III)
this group being attached by way of, at least one N-bonded alkylene group having 1 to 4 carbon atoms to at least one silicon atom, a and b being identical or different and being an integer from 0 to 6, r being 0 or 1, s being 0 or 1, subject to the proviso that when a=0 then r=0 and when b=0 then s=0,
at least one Si—C-bonded linear, branched or cyclic alkyl group having 1 to 16 carbon atoms,
and at least one hydroxyl and/or alkoxy group; and
(v) a mixture thereof, and
(B) subsequently in a second step applying a further coat using an organosiloxane as per (i) or an organosiloxane-containing composition as per (ii) to the treated substrate.
The present invention accordingly provides a process for producing an ink, paint, pollutant, bioorganism, oil, water and/or dirt repellent coat on an inorganic substrate, which comprises:
A) applying to a substrate a composition comprising at least one alkyl-functional alkyltrialkoxysilane; and
B) applying to said substrate in a second step a composition comprising an organosiloxane selected from the group consisting of
(i) an

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