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
2000-07-18
2004-03-02
Metzmaier, Daniel S. (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...
C525S477000, C523S201000, C516S059000, C516S076000, C524S837000
Reexamination Certificate
active
06699930
ABSTRACT:
TECHNICAL FIELD
The invention pertains to an aqueous 1-component composition which forms a resilient silicone network on drying.
BACKGROUND ART
All water-based silicone coating systems based on crosslinking silicones have required an additional catalyst component which, for example, is added only shortly before actual use, in order to prevent premature gellation. A typical example is the platinum-catalyzed vulcanization of silicones containing vinyl groups with silicones carrying Si—H groups, for example in paper coating or fabric coating. The following aqueous composition is known for coating as an emulsion:
1) An oil-in-water emulsion of siloxane oils carrying vinyl groups which are stabilized with anionic or nonionic surfactants;
2) An oil-in-water emulsion of siloxane oils carrying Si—H groups which are stabilized with anionic or nonionic surfactants;
3) Optionally a filler;
4) A catalyst component (platinum compound); and
5) Optionally an inhibitor.
A further type of crosslinkable emulsion is based on crosslinking silicone oils having &agr;,&ohgr;-alkoxy or hydroxyl functions, which is catalyzed with the aid of metal salts, e.g. tin compounds, which optionally may also contain borates. Such systems have the following composition:
1) An oil-in-water emulsion of &agr;,&ohgr;-dihydroxypolyorganosiloxane and/or &agr;,&ohgr;-dialkoxyorganosiloxane, stabilized with an anionic or nonionic surfactant;
2) A crosslinking agent, such as colloidal silica gel, sodium silicate (=catalyst), siliconates, or microemulsions of silsesquioxanes or silicone resins, polysilicates, polyalkoxysilanes;
3) An inorganic or organic filler; and
4) A catalyst for curing (e.g. salts of the metals tin, lead, calcium, barium, zirconium or iron).
The two water-based coating systems described above also have further disadvantages in addition to the aforementioned catalyst problem:
A) the individual components or at least the catalyst component must be stored separately and can be mixed in only shortly before use, i.e. complicated process engineering during application;
B) the emulsions have only very limited shelf-life, shear stability and thermal stability;
C) in the case of high solids contents, the viscosity increases greatly;
D) the compositions exhibit high shrinkage on drying; and
E) the compositions demonstrate poor adhesion to the substrate.
A further type of system crosslinkable in situ comprises, for example, silicone oils which carry &agr;,&ohgr;-dialkoxy-terminated amino groups which readily crosslink on application (e.g. to textiles). The disadvantage of this type of coating is its low crosslinking density and problems associated therewith, such as poor mechanical properties, poor permanence on the substrate, a large amount of extractables, “exudation” of silicone oil, etc.
DISCLOSURE OF INVENTION
An object of the present invention was to provide an aqueous 1-component system which has a long shelf-life and forms a resilient silicone network on drying, without the addition of a catalyst.
BEST MODE FOR CARRYING OUT THE INVENTION
The invention pertains to aqueous 1-component compositions which form resilient silicone networks on drying and are obtained by reaction, at a temperature of at least 40° C., of
I) a surfactant-stabilized dispersion of at least one highly crosslinked silicone compound which carries reactive groups, selected from silanol, hydrocarbon-oxy and silanolate groups with
II) a surfactant-stabilized emulsion of at least one optionally precrosslinked silicone oil which carries reactive groups, selected from silanol, hydrocarbon-oxy and silanolate groups.
This composition cures on drying without the addition of a catalyst. The composition is distinguished by its long shelf-life, even at elevated temperature, and its high shear stability. At the same time, low viscosities at high solids content and filler content can be achieved with this composition.
Silicone dispersion (I), which may also be referred to as polyorganosilicic acid sol, preferably contains highly crosslinked silicone compound (Ia) composed of units of the general formulae (Ia-1) to (Ia-4):
30 to 100 mol % of
R
(1−a)
(R
1
O)
a
SiO
3/2
(Ia-1),
20 to 100 mol % of
(R
1
O)
b
SiO
(4−b)/2
(Ia-2),
0 to 70 mol % of
R
(2−c)
(R
1
O)
c
SiO
2/2
(Ia-3),
0 to 50 mol of
R
(3)
SiO
1/2
(Ia-4),
in which
R may be identical or different and is a hydrogen atom or an Si—C-bonded C
1
- to C
30
-hydrocarbon radical which optionally may also be substituted by halogen atoms or may carry one or more functional groups,
R
1
may be identical or different and may be a hydrogen atom, an alkali metal or alkaline earth metal atom, or a monovalent C
1
- to C
16
-hydrocarbon radical which optionally may also carry halogen atoms, the hydrocarbon chain of which may be interrupted by hetero atoms such as oxygen,
a is 0 or 1,
b is 0, 1, 2 or 3 and
c is 0 or 1.
Examples of functional groups which may be present in R are double bonds such as the vinyl group, the acrylate group, etc.; or amino groups such as the aminopropyl or aminopropylaminoethyl group or a cyclohexylamine group; a mercapto group such as the mercaptopropyl group; epoxy groups; acid anhydride groups; acid groups; etc. Preferred radicals R in each case are the C
1
- to C
6
-alkyl radicals and the phenyl radical, in particular the unsubstituted radicals of these types, and the methyl radical.
Silicone compound (Ia) preferably contains, in each case independently of one another,
60 to 100 mol % of units of the general formula Ia-1,
60 to 100 mol % of units of the general formula Ia-2,
0 to 40 mol % of units of the general formula Ia-3,
0 to 20 mol % of units of the general formula Ia-4.
Silicone dispersion (I) may contain silanes of the general formula (Ib)
R
(4−d)
Si(OR
1
)
d
(Ib)
in which
R and R
1
have the above meaning and
d may be 1, 2, 3 or four.
100 parts of silicone dispersion (I) preferably contain 1 to 50 parts, in particular 5 to 30 parts, of silicone compound (Ia) and 0.5 to 20 parts, in particular 1 to 10 parts, of surfactant and may also contain 0 to 30 parts, in particular 5 to 20 parts, of an alcohol and 0 to 5 parts, in particular 0 to 2 parts, of the silane of the general formula (Ib). The remaining amount to 100 parts in each case comprises water. “Parts” as used herein means parts on a mass basis.
Silicone oil emulsion (II) contains silicone oils of the general formula II
(R
1
O)
(3−e)
R
e
SiO—(R
2
SiO)
x
—(RSiO
3/2
)
y
—(SiO
4/2
)
z
—O—SiR
e
(R
1
O)
(3−e)
in which
R and R
1
have the above meanings and
e is 0, 1 or 2,
x is 2 to 1,000,000,
y is 0 to 100,000, in particular 0 to 100, and
z is 0 to 100,000, in particular 0 to 100, and
y+z: x is not more than 1:10, in particular not more than 1:40.
100 parts of the silicone oil emulsion (II) preferably contain 1 to 60 parts, in particular 20 to 40 parts, of silicone oils (IIa) and 0.5 to 40 parts, in particular 5 to 15 parts, of surfactant, and may also contain 0 to 20 parts, in particular 0 to 10 parts, of an alcohol and 0 to 5 parts, in particular 0 to 2 parts, of the silane of the general formula (Ib). The remaining amount to 100 parts in each case, comprises water. Silicone oil emulsion (II) is preferably of the oil-in-water type.
The pH of the silicone dispersion (I) and of the silicone oil emulsion (II) may vary in each case from 0 to 14.
In addition, the composition may also contain 0 to 100 parts of acidic, neutral, basic, inorganic or organic additives, such as fillers, water-soluble or water-dispersible oligomers or polymers. The additives may originate from the silicone dispersion (I) and/or from the silicone oil emulsion (II) or may be added to the composition. The solids content of the composition may vary preferably from 5% by weight to 90% by weight, with 20 to 70% by weight solids being particularly preferred, in particular 25 to 40% by weight solids.
Preferred examples of inorganic fillers are precipitated silica, pyrogenic silica, titanium dioxide, basic or acidic aluminas, etc. Organic fillers are, for example, aqueous latices, such as
Baumann Frank
Deubzer Bernward
Lässig Antje
Schmidt Manfred
Brooks & Kushman P.C.
Metzmaier Daniel S.
Wacker-Chemie GmbH
LandOfFree
Aqueous 1-component silicone composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aqueous 1-component silicone composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aqueous 1-component silicone composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3203614