Fluoroalkyl-functional organopolysiloxane-containing...

Details Fluoroalkyl-functional organopolysiloxane-containing... Fluoroalkyl-functional organopolysiloxane-containing...

1999-01-12

2001-05-08

Moore, Margaret G. (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, C427S387000, C427S221000, C428S447000, C528S042000

Reexamination Certificate

active

06228936

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to fluoroalkyl functional group containing organopolysiloxane-containing compositions based on water/ alcohol, to a process for their preparation and to their use.
2. Description of the Background
Organosilanes of the formula R′-Si(R″)
3
, wherein R′ is a fluorinated organic radical and R″ is a chlorine, methoxy or ethoxy radical, have diverse uses, for example for application of hydrophobically and oleophobically acting layers to surfaces.
It is known that oil- and water-repellent coatings on surfaces, usually glass surfaces, are produced with the aid of fluoroalkylalkoxysilanes and fluoroalkylchlorosilanes. The coatings can be used, for example, to provide plate glass with a dirt-repellent treatment. The processes described are based on sol-gel processes, very fine inorganic particles being produced and employed together with the fluoroalkylsilane. The application of such systems is technically demanding and usually uses complex organic solvent mixtures and additives (European Laid-Open Application No. 0 658 525 and European Laid-Open Application No. 0 629 673).
Large amounts of organic solvents are also employed for the production of oil and water-repellent coatings; for example, an ethanol content of 52% by weight is used in formulations shown in U.S. Pat. No. 5,424,130.
In the processes described, the complicated application processes, on the one hand, and the use of organic solvents, on the other hand, have adverse effects. In some processes, even substances which are very problematic ecologically such as chlorinated hydrocarbons or fluorohydrocarbons, are employed as solvent in a considerable concentration (European Laid-Open Application No. 0 491 251 and European Laid-Open Application No. 0 493 747). A need continues to exist for aqueous based solutions of organosilanes which provide water and oil resistant coatings.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide an organosilane system which is soluble in an aqueous system and with which a simultaneously hydrophobic and also oleophobic coating can be produced on substrates in an impregnating process which is easy to conduct.
Another object of the present invention is to provide such systems for a simplified treatment of substrates such as, for example, glass such as glass fibers, fillers and pigments, metals, plastic, textile fibers—including cotton, wood, paper and mineral fibers, and mineral building materials, for example, lime sandstone, concrete, brick or ceramic.
Briefly, these objects and other objects of the present invention as hereinafter will become more readily apparent can be attained by an aqueous alcoholic fluoroalkyl functional group containing organopolysiloxane composition which comprises organopolysiloxanes of the formula I:
RO[Si(A)(CH
3
)
z
(OR)
1−z
O]
a
[Si(B)(R
2
)
y
(OR)
1−y
O]
b
[Si(C)(CH
3
)O]
c
[Si(D)(OR)O]
d
R.(HX)
e
  (I)
in which A is an aminoalkyl radical derived from the compound of formula II:
H
2
N (CH
3
)
t
(NH)
g
(CH
2
)
h
Si (OR)
3−z
(CH
3
)
z
  (II)
in which 0≦f≦6, 9=0 if f=0 and g=1 if f>0, 0≦h≦6 and 0≦z≦1, and B is a fluoroalkyl radical derived from the compound of formula III:
R
1
—Y
m
—(CH
2
)
2
Si(R
2
)
y
(OR)
3−y
  (III)
wherein R
1
is a mono-, oligo- or perfluorinated alkyl group having 1-9 C atoms or a mono-, oligo- or perfluorinated aryl group, Y is a CH
2
, O or S group, R
2
is a linear, branched or cyclic alkyl group having 1-8 C atoms or an aryl group and O≦y≦1 m is 0 or 1 , is and C is an alkyl radical derived from the compound of formula IV:
R
3
—Si(CH
3
)(OR)
2
  (IV)
and D is also an alkyl radical derived from the general formula V:
R
3
—Si(OR)
3
  (V)
wherein R
3
in the preceding formulae, in each case is identical or different, is a linear, branched or cyclic alkyl group having 1-8 C atoms, R in the preceding formulae, in each case is identical or different, and is a linear, branched or cyclic alkyl group having 1-8 C atoms or an aryl group and HX is an acid, in which X is an inorganic or organic acid anion such as, for example, chloride, nitrate, formate or acetate, and 0≦y≦1, 0≦z≦1, a>0, b>0, c≧0, d≧0, e≧0 and (a+b+c+d)≧2, preferably (a+b+c+d)≧4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Surprisingly, it has been found that cocondensates of aminoalkylalkoxysilanes and fluoroalkylalkoxysilanes form water-soluble compositions by addition of acids, and such solutions are outstandingly suitable for providing substrates with coatings which are simultaneously hydrophobic and oleophobic. Such aqueous alcoholic organopolysiloxane-containing compositions contain Si-bonded fluoroalkyl functional groups are then accessible as homogeneous, clear solutions, which are stable for several weeks. Such compositions are obtained when a mols of water-soluble aminosilanes of formula II, b mols of fluoroalkyl-functional organosilanes of formula III, and c mols and d mols of non-water soluble organosilanes of formulas IV and V, are mixed in a molar ratio of M=[a/(b+c+d)]≧2 0.1 where a>0, b>0, c≧0, d≧0, and the organosilane mixture is mixed with water or a water/acid mixture and/or a water/acid/alcohol mixture, the amount of acid suitably being selected such that the reaction mixture has a pH in the range from 1-8. The active compound concentration is suitably adjusted by addition of alcohol or water or an alcohol water mixture after a reaction time of 0.5-24 hours, preferably 1-12 hours, particularly preferably after 2-6 hours. Organosilane polycondensates prepared in this manner have the plausible approximate structure shown in formula I (see above). Complete clarification of the structure by the usual methods of polymer analysis is not possible because of the very high reactivity of the organofunctional siloxanes, and a small proportion of hydroxyl groups instead of the Si bonded alkoxy groups in compounds of formula I, therefore, also cannot be excluded. The content of organopolysiloxanes containing fluoroalkyl groups as the active compound in the composition of the invention is suitably 0.005-85% by weight, preferably 0.01-10% by weight, particularly preferably 0.5-2% by weight. The content of free alcohol, i.e. the proportion of alcohol which the composition comprises as a medium, preferably is 3-50% by weight, particularly preferably more than 5% by weight to 50% by weight.
The composition according to the invention comprises a monobasic inorganic and/or organic acid and/or secondary products thereof, the composition preferably having a pH of 1-8, particularly preferably a pH of 1-6, and especially preferably a pH of 1-5. The term secondary products at this point is to be understood as meaning compounds such as alkali metal halides, in particular sodium chloride or potassium chloride, alkali metal acetates, alkali metal formates, alkali metal nitrates or compounds of the amino groupings in the organopolysiloxanes with inorganic or organic acid radicals such as are within the scope of formula I.
The aqueous alcoholic fluoroalkyl functional group containing organopolysiloxane composition can be prepared by:
mixing water-soluble organosilanes of formula II:
H
2
N(CH
2
)
f
(NH)
g
(CH
2
)
h
—Si(CH
3
)
z
(OR)
3−z
  (II)
wherein 0≦f≦6, g=0 if f=0 and g=1 if f>1, 0≦h≦6, 0≦z≦1 and R is a linear, branched or cyclic alkyl group having 1-8 C atoms or an aryl group, with fluoroalkyl-functional organosilanes of formula III:
R
1
—Y
m
—(CH
2
)
2
Si(R
2
)
y
(OR)
3−y
  (III)
wherein R
1
is a mono-, oligo- or perfluorinated alkyl group having 1-9 C atoms or a mono-, oligo- or perfluorinated aryl group, Y is a CH
2
, O or S group, R
2
and R are each independently a linear, branched or cyclic alkyl group

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