Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2001-11-08
2003-11-18
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S428000, C428S429000, C428S446000, C428S450000, C427S387000, C524S858000, C528S033000, C528S034000, C528S036000, C528S042000
Reexamination Certificate
active
06649272
ABSTRACT:
The present invention relates to a composition comprising the condensation product of at least one fluorochemical polyether silane compound having a polyfluoropolyether segment and at least two hydrolysable silane groups per molecule with one or more non-fluorinated compounds having at least two hydrolysable groups per molecule. The present invention also relates to the use of the composition for providing durable repellency to water, oil and stain to a substrate.
In the past, various efforts have been made to provide repellent properties to a substrate. For example, U.S. Pat. No. 4,687,707 (=EP-A-0 166 363) describes a low reflectance, transparent material having anti-soiling properties, which comprises a transparent substrate having a coating comprising a thin layer of a condensation product of a fluorine containing silicon compound having a polyfluorinated or perfluorinated carbon chain.
WO 99/03941 relates to a coating material comprising condensates of at least one compound (A) of the general formula R
a
MZ
b
(a=0 to 3; b=1 to 4; a+b=3, 4), and at least one compound (B) of the general formula R′
x
MZ
y
(x=1 to 3; y=1 to 3; x+y=3,4), wherein R is a non-hydrolysable organic group, M is an element selected from the main groups III to V or from the subgroups II to IV of the periodic table of elements, Z is a hydrolysable group, and at least one R′ contains a perfluoropolyether structure separated from M by at least two atoms, and at least one R is not equal to at least one R′. The composition is used to provide oleophobic properties to substrates, such as porous polymers.
U.S. Pat. No. 5,739,369 (=EP-A-0 738 771) relates to a water-soluble surface treating agent comprising the reaction product of (A) a fluoroalkyl group-containing alkoxysilane with (B) an amino-group-containing alkoxysilane and optionally further with (C) an alkyl group-containing alkoxysilane. The agent is diluted with water to form a solution for treating glass and other substrates to impart thereto properties, such as water repellency.
U.S Pat. No. 5,919,886 relates to a fluorine-containing organo-silicon compound useful for obtaining elastomers and to room temperature curable silicon compositions containing the same compound.
U.S. Pat. No. 5,306,758 (=EP-A-0 433 070) describes fluorocarbon based, curable, crosslinkable compositions and coatings prepared therefrom that can be used to form low-surface energy release liners.
U.S. Pat. No. 5,922,787 (=EP-0 797 111) relates to a composition containing an alkoxy-silane compound having a perfluoropolyether group. The composition may be used for forming an anti-fouling film.
However, our findings indicate that while some of the previously known surface coatings may be capable of providing acceptable levels of initial repellent properties, a loss of repellency is often encountered due to abrasion of the coating. Also, if non-fluorine containing components are additionally employed in the coating composition, a step-wise hydrolysis is often required (see for example U.S. Pat. No. 5,644,014), wherein in a first step a precondensation of the non-fluorinated silane is carried out and only subsequently the fluorinated silane compound may be added. If a one-step hydrolysis is carried out, often phase separation occurs thereby leading to non-homogenous coatings having insufficient repellent properties.
Accordingly, it is desirable to provide a coating composition capable of providing a highly durable water, oil and/or stain repellent coating on a substrate. In particular, it is desirable to provide a durable coating wherein the initial, repellent properties are substantially maintained, even under abrading conditions. Further, the coating compositions preferably can be applied and used in an environmental friendly way and can be produced in a reliable, convenient and cost effective way.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a composition comprising the reaction product obtainable after a substantially complete condensation reaction of (A) one or more fluorochemical polyether silane compound(s) having a polyfluoropolyether segment and at least two silane groups —Si(Y)
3−x
(R
1
)
x
per molecule, wherein R
1
represents an alkyl group, Y represents a hydrolysable group and x is 0 or 1; and (B) a substantial amount of one or more non-fluorinated compounds of an element M selected from the group consisting of Si, Ti, Zr, B, Al, Ge, V, Pb, Sn and Zn and having at least two hydrolysable groups per molecule. By the term “substantially complete condensation reaction” is meant that the reaction is either complete or at least 80% of the hydrolysable groups in the mixture have disappeared, preferably at least 90%. Completion of the reaction can be monitored through the use of infrared spectroscopy and C
13
—NMR.
In a further aspect, the present invention provides a method for preparation of the condensation product. In a still further aspect, the present invention also provides a method for treating a substrate, comprising the step of applying to the substrate the composition as defined above. The fluorochemical compositions can be used to treat substrates and are capable of rendering such substrates oil and water repellent and/or to provide stain repellency thereto.
The compositions are generally effective at low levels of application and have good durability. The compositions are particularly useful for rendering substrates such as ceramics, metal, polymeric substrates and glass repellent to water and/or oil.
In one embodiment, a homogeneous reaction product mixture can be obtained by simply mixing the components in a suitable solvent, in the presence of reagent water, and optionally of a catalyst. There is no need for a two-step reaction; where in a first step a precondensate of compound (B) is formed and in a second step, the fluorochemical polyether disilane (A) is added. Accordingly, the reaction product of the invention can be produced in an easy and reliable way.
By the term “homogeneous mixture” in connection with the present invention is meant that the composition is stable, for at least 24 hours, preferably 1 month, at room temperature. Some haziness may occur, however without substantial precipitation or phase separation occurring.
The term “hydrolysable group” in connection with the present invention refers to a group which either is directly capable of undergoing condensation reactions under appropriate conditions or which is capable of hydrolyzing under appropriate conditions, thereby yielding a compound, which is capable of undergoing condensation reactions. Appropriate conditions include acidic or basic aqueous conditions, optionally in the presence of a condensation catalyst.
Accordingly, the term “non-hydrolysable group” as used in the present invention refers to a group not capable of either directly undergoing condensation reactions under appropriate conditions or of hydrolyzing under the conditions listed above for hydrolyzing the hydrolyzable groups.
The term “substantial amount” of a compound as used herein refers to an amount of a compound greater than a catalytic amount of that compound necessary for promoting a certain reaction (e.g., condensation reactions). Accordingly, a composition comprising a substantial amount of that compound generally allows the compound to act as a reactant such that the resulting product is formed of at least part of that compound.
DETAILED DESCRIPTION
Component (A) comprises at least one fluorochemical polyether silane compound having a polyfluoropolyether segment and at least two silane groups —Si(Y)
3−x
(R
1
)
x
per molecule, wherein R
1
represents an alkyl group (for example a C
1
-C
8
, preferably C
1
-C
4
primary or secondary alkyl group), Y represents a hydrolysable group and x is 0 or 1.
Preferably, component (A) is a fluorochemical polyether silane compound according to formula (I)
R
f
[Q—C(R)
2
—Si(Y)
3−x
(R
1
)
x
]
z
(I)
wherein R
f
represent
Dams Rudolf J.
Fieuws Franceska M.
Moore George G. I.
Piessens Guido P.
3M Innovative Properties Company
Dawson Robert
Feely Michael J
Kokko Kent S.
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