Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2001-09-20
2003-11-18
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S447000, C428S450000, C528S030000, C528S038000, C528S042000, C524S800000, C524S837000
Reexamination Certificate
active
06649273
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a substantially aqueous emulsion comprising a fluorocarbon silane or hydrolyzate thereof, or both; to a composition or product comprising the emulsion; and to a heat-resistant and/or water-repellent coated product comprising the composition.
BACKGROUND OF THE INVENTION
All trade names or trademarks are shown in capital letters.
U.S. Pat. No. 5,550,184 discloses an emulsion containing a fluorocarbon silane hydrolyzed product and a surfactant for emulsifying the hydrolyzed product that does not require a special heat treatment and can provide the water repellency to the base material.
Japanese Kokai Patent Application Hei 11[1999]-181355 discloses an emulsion containing fluorocarbon silane hydrolyzed product, surfactant for emulsifying the hydrolyzed product, and specific silicate, in which pH is adjusted to 7 or more. A characteristics is that it can maintain an excellent water repellency even under a high-temperature condition, that is, heat resistance and water repellency can be provided to a base material.
Japanese Kokai Patent Application Hei 11[1999]-181355 disclose an emulsion containing a hydrolyzed product of a fluorocarbon silane emulsified with a specific nonionic surfactant and a specific silicate, and an emulsion in which pH is adjusted to 4 or more. The emulsion exhibits heat resistance and water repellency.
However, a coated layer containing these emulsions is not as durable as one skilled in the art would desire. Additionally, though these emulsions exhibit water-repellency characteristics, they do not exhibit oil-repellent property. For example, glass window of oven, range, or toaster can be coated with a layer formed by an emulsion having good water repellency at high temperature, but it has a poor oil-stain resistance. It is also highly desirable to develop an emulsion that can exhibit both water-repellent and oil-repellent properties for a variety of applications.
Therefore, there is an increasing need to develop a composition containing the emulsion for coating on glass windows of, for example, oven range and toaster as well as precision products related to automobiles. Also desired is an improved heat resistance, water repellency, and durability of the layer coated on the glass.
SUMMARY OF THE INVENTION
A product or composition comprises a substantially aqueous emulsion, which comprises, or is produced by combining, a fluorocarbon silane or hydrolyzate thereof; a surfactant, a silicon-containing compound, and optionally a film-forming agent wherein the film-forming agent is silicon dioxide, titanium dioxide, zirconium dioxide, organoalkoxysilane, polysilazane, or combinations of two or more thereof.
A product comprises, or is produced by combining, a substrate, an emulsion, and optionally an undercoat layer between the substrate and the emulsion wherein the emulsion comprises or is produced by combining a fluorocarbon silane or hydrolyzate thereof, a surfactant, and a silicon-containing compound; the silicon-containing compound is silicate, organoalkoxysilane, aminosilane, epoxysilane, mercaptosilane, or combinations of two or more thereof; and the undercoat layer comprises or is produced from at least one film-forming agent, which is silicon dioxide, titanium dioxide, zirconium dioxide, organoalkoxysilane, polysilazane, or combinations of two or more thereof.
DETAILED DESCRIPTION OF THE INVENTION
The term “hydrolyzate” is a hydrolyzed product of a fluorocarbon silane. The fluorocarbon silane can have the structure of R
f
—(CH
2
)
p
—Si(—(O—CH
2
CH
2
)
n
—OR′)
3
; R
f
is a perfluoroalkyl group having 3 to 18 carbon atoms or a mixture of perfluoroalkyl groups having 3-18 carbon atoms; each R′ can be the same or different and is independently an alkyl group having 1 to 3 carbon atoms; p=1-4 and n=2-10, all inclusive. When p and n are each 2, the fluorocarbon is preferably a perfluoroalkylethyl tris(2-(2-methoxyethoxy)ethoxy)silane, and when p is 2 and n is 3, it is preferably a perfluoroalkylethyl tris(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)silane. Such a fluorocarbon silane can be manufactured by any well-known method and commercially available. If two or more fluorocarbon silanes are used, they are generally mixed together.
The silicon-containing compound can be any silicon compound that is polymerizable and can produce an emulsion having the desired characteristics disclosed herein. The silicon compound can be copolymerized with the fluorocarbon silane hydrolyzed product to improve heat resistance and water repellency of the emulsion and the coating layer containing the emulsion.
The preferred silicon compounds include, but are not limited to, silicate, organoalkoxysilane compound, aminosilane compound, epoxysilane compound, mercaptosilane compound, and combinations of two or more thereof.
A preferred silicate can have the structure of Si—R
4
; R is at least one organic radical selected from a group consisting of OCH
3
, OCH
2
CH
3
, (OCH
2
CH
2
)
m
OCH
3
, and m=1-10. The more preferred silicate is Si((OCH
2
CH
2
)
m
OCH
3
)
4
where m=1-3 for it is water soluble. The most preferred silicate is Si—((OCH
2
CH
2
)
2
OCH
3
)
4
.
A preferred organoalkoxysilane can have the structure of R
1
w
Si(OR
2
)
4−w
; R
1
and R
2
are each independently one or more alkyl groups having 1-5 carbons; and w is a number from 1 to 3, inclusive. The most preferred organoalkoxysilane is organomethoxysilane.
A preferred aminosilane, epoxysilane, or mercaptosilane can have the formula of R
3
R
4
X
SiR
5
y
(OR
6
)
3−(X+y)
; R
3
is a radical containing amino group, epoxy group, glycidoxy group, thiol group, or combinations of two or more thereof; R
4
, R
5
, and R
6
can be the same or different and are each independently an alkyl group having 1-5 carbons or a mixture of the alkyl groups; x=0-1; y=0-1; and x+y≦2. When R
3
is an amino group, R
4
can also be substituted by an amino group.
Specific examples of preferred aminosilane compounds include, but are not limited to, N-(2-aminoethyl) 3-aminopropylmethyl dimethoxysilane, N-(2-aminoethyl) 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, and combinations of two or more thereof.
Specific examples of preferred epoxysilane compounds include, but are not limited to, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyldimethoxysilane, and combinations thereof.
Specific examples of preferred mercaptosilane compound includes, but is not limited to, 3-mercaptopropyl trimethoxysilane.
When oil resistance and stain resistance are desired along with the heat resistance and the water repellency in the coated product, an organoalkoxysilane is preferable among the silicon compounds.
The silicon compound can be used at any amount effective to produce an emulsion having desired heat resistance and water repellency. Generally the mole ratio of a silicon compound to of the fluorocarbon silane or its hydrolyzed product can be in the range of from about 0.3:1 to about 10:1, preferably 0.3:1 to 5:1, and more preferably 0.4:1 to 2:1.
Any surfactant that can emulsify a fluorocarbon silane or its hydrolysis product can be used. The surfactant generally is a surfactant having an HLB value sufficiently high to inhibit self-condensation of the fluorocarbon silane hydrolysis product. The term “HLB” refers to the HLB system published by ICI America's, Inc., Wilmington, Del.; Adamson, A. W., “Physical Chemistry of Surfaces”, 4
th
edition, John Wily & Sons, New York, 1982). The surfactant can be anionic, cationic, nonionic, amphoteric, or combinations thereof. The preferred surfactants are those with HLB values greater than 12, more preferably greater than 16. Generally, the lower HLB value the surfactant is, the larger amount of the surfactant is required to stabilize the emulsion. Two or more miscible surfactants generally can also be combined or mixed for use as long as they have HLB values sufficiently high to inhibit self-condensation of the fluorocarbon silane or its hydrol
Iwato Satoko
Kaku Mureo
Dawson Robert
E. I. du Pont de Nemours and Company
Zimmer Marc
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