Emulsion and water-repellent composition

Details Emulsion and water-repellent composition Emulsion and water-repellent composition

2002-10-18

2004-03-23

Moore, Margaret G. (Department: 1712)

Compositions: coating or plastic

Coating or plastic compositions

Silicon containing other than solely as silicon dioxide or...

C106S287160, C528S023000, C528S014000, C528S039000, C528S042000, C528S013000, C528S021000, C528S012000

Reexamination Certificate

active

06709504

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an emulsion composition comprising a fluorocarbon silane or hydrolyzate thereof and coated composition produced therefrom.
BACKGROUND OF THE INVENTION
Some silane-containing aqueous solutions that can provide water-repellent characteristics on the surface of a substrate have been disclosed. See, e.g., U.S. Pat. Nos. 4,648,904, 4,757,106, 4,990,377, 5,196,054, 5,550,184, and 5,664,014, European Patent 0 748 357, and Japanese Kokai Patent Application No. Hei 11(1999)-181355.
For example, U.S. Pat. No. 5,550,184 discloses reactive hydrolyzed silane emulsions produced by emulsifying a hydrolyzable alkoxysilane in water in the presence of a high HLB value emulsifier to simultaneously retain the hydrolyzable alkoxysilane in substantially totally hydrolyzable state. The emulsion can produce durable coatings that impact water-repellent characteristics on a substrate.
Japanese Kokai Patent Application No. Hei 11(1999)-181355 discloses an emulsion containing a specific type of silane hydrolyzate, a specific type of silicate a substance, and a surfactant. The emulsion, however, requires pH adjustments to alkaline region in order to exhibit water-repellency and heat resistance characteristics.
Therefore, it is desirable to develop a new emulsion or coating containing the emulsion that does not require the alkaline pH adjustment to exhibit the desired heat-resistance and water-repellency properties.
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. Therefore, 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, it is desirable to develop a new emulsion or coating containing the emulsion that does not require the alkaline pH adjustment, or without the need of metal hydroxide or the chemicals disclosed above, to exhibit the desired heat-resistance and water-repellency properties.
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. Therefore, it is also highly desirable to develop an emulsion that can exhibit both water-repellent and oil-repellent properties for a variety of applications.
SUMMARY OF THE INVENTION
A composition comprises a fluorocarbon silane or hydrolyzate thereof; a surfactant; a polymerizable, silicon-containing compound; and a catalyst.
DETAILED DESCRIPTION OF THE INVENTION
The fluorocarbon silane generally contains at least one hydrolyzable fluorocarbon silane and can be represented by R
f
—(CH
2
)
p
—Si{—(O—CH
2
CH
2
)
n
—OR′}
3
where R
f
can be one or more C
3-18
perfluoroalkyl groups, each R′ can be the same or different and is independently a C
1-3
alkyl groups or combinations thereof, p=2-4, and n=2-10). The preferred R
f
is mixed perfluoroalkyl groups of 8 to 18 carbons.
Examples of the fluorocarbon silanes include, but are not limited to, perfluoroalkylethyltris (2-(2-methoxyethoxy)ethoxy)silane when n is 2, and perfluoroalkylethyltris (2-(2-(2-methoxyethoxy)ethoxy)ethoxy)silane when n is 3, and combinations thereof. These fluorocarbon silanes are either commercially available or can be produced by any means known to one skilled in the art as disclosed in Kir-Othmer Encyclopedia of Chemical Technology, 3
rd
edition, vol. 20. For example, the fluorocarbon can be produced by the method disclosed in U.S. Pat. No. 5,550,184, disclosure of which is incorporated herein by reference.
Any surfactant that can emulsify the hydrolysis product of the fluorocarbon silane 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 are surfactants having HLB values sufficiently high to inhibit self-condensation of the fluorocarbon silane hydrolysis products.
The HLB value of a nonionic surfactant can be determined by calculation with a formula, among others, originated by Griffin of Atlas Co. (now ICI America) in the U.S. However, in the case of the anionic type or the cationic type, a method for determination by calculation of the HLB value is not available to date. Nevertheless, paying attention to the fact that changes in emulsification characteristics are sensitive to changes in the HLB value, Atlas Company established and published a method for the experimental determination of the HLB value by an emulsification experiment on standard oil. Companies other than Atlas have also established methods for experimental determination of HLB value. However, it can be clarified by the adoption of any experimental method that the HLB value of the anionic type or the cationic type is greater than 16.
Examples of nonionic surfactants include, but are not limited to, R′
f
—CH
2
CH
2
—O—(CH
2
CH
2
O)
11
—H, C
9
H
19
—C
6
H
4
—O—(CH
2
CH
2
O)
50
—H, other nonionic surfactants, and combinations thereof Examples of cationic surfactants include, but are not limited to R′
f
—CH
2
CH
2
SCH
2
CH(OH)CH
2
N(CH
3
)
3
+
Cl
−
, other cationic surfactants, and combinations thereof. Examples of anionic surfactants include, but are not limited to, C
12
H
25
(OCH
2
CH
2
)
4
OSO
3
−
NH
4
+
, C
12
H
27
—C
6
H
4
—SO
3
−
Na
+
, other anionic surfactants, and combinations thereof. In each of the formulae, R
f
′ is a perfluoroalkyl group generally having about 3-18 carbon atoms. The preferred surfactants are nonionic surfactants having polyethylene glycol in the molecular chain.
The content of the fluorocarbon silane in the water-based emulsion can be about 0.1 weight % or higher, preferably about 2-20 weight %, and most preferably 7-15 weight %, based on the total weight of the emulsion. The weight ratio of the fluorocarbon silane to the surfactant can be in the range of from about 1:1 to about 10:1, preferably about 10:2 to about 10:5, and even more preferably 10:3.
Any polymerizable, silicon-containing compound can be used so long as it can copolymerize with the fluorocarbon silane hydrolysis product to improve heat-resistant water-repellent characteristics, heat-resistant oil-repellent characteristics, or both. Suitable polymerizable, silicon-containing compounds include silicates, organosilanes, or combinations thereof.
A suitable silicate can have the formula of Si—R
4
where R is one or more groups selected from the group consisting of OCH
3
, OCH
2
CH
3
, (OCH
2
CH
2
)
m
OCH
3
, and combinations thereof in which m=1-10, preferably 1-3. Because a silicate represented by Si—((OCH
2
CH
2
)
m
OCH
3
)
4
(m=1-3) is water-soluble, it can dissolve in a water-based emulsion containing a fluorocarbon silane hydrolysis product in a relatively short time, the silicate represented by Si—((OCH
2
CH
2
)
2
OCH
3
)
4
is presently preferred.
The silicate to the fluorocarbon silane molar ratio can be in the range of from about 0.3:1 to about 10:1, preferably 0.3:1 to 5:1, and most preferably 0.4:1 to 2:1 Suitable organosilane include

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