Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-05-19
2001-03-13
Nakarani, D. S. (Department: 1773)
Stock material or miscellaneous articles
Composite
Of silicon containing
C106S287110, C106S287140, C106S287160, C428S429000, C428S450000, C428S451000, C556S413000, C556S418000, C556S419000
Reexamination Certificate
active
06200684
ABSTRACT:
This invention relates to a novel perfluoropolyether-modified aminosilane which cures into a film having improved water and oil repellency, parting and anti-staining properties, a surface treating agent comprising the aminosilane, and an article with a cured coating of the aminosilane.
BACKGROUND OF THE INVENTION
In general, perfluoropolyether-containing compounds have water and oil repellency, chemical resistance, lubricity, parting properties and anti-staining properties because of their very low surface energy. For the effective utilization of such properties, these compounds are widely used in the industry as water/oil repellent anti-staining agents for paper and fibers, lubricants in magnetic recording media, oil repellants in precision machines, parting agents, cosmetics, and protective coatings.
However, the perfluoropolyether-containing compounds also have such properties as non-tackiness and non-adhesion to other substrates. They are applicable to the substrate surface, but cannot form a coating firmly bonded to the substrate.
Silane coupling agents are well known as the means for establishing a firm bond between a substrate surface such as glass or fabric and an organic compound. The silane coupling agent has an organic functional group and a reactive silyl group (typically alkoxysilyl group) in a molecule. The alkoxysilyl group undergoes self-condensation reaction with air-borne moisture, converting to a siloxane to form a coating. At the same time, the silane coupling agent forms chemical and physical bonds with the surface of glass or metal, resulting in a durable tough coating. By virtue of these advantages, the silane coupling agent is widely used as a coating agent to a variety of substrates.
As one typical example taking advantage of the above features, JP-A 58-167597 discloses a fluoroaminosilane compound of the following formula (3):
wherein R
1
and R
2
are C
1-4
alkyl, Q is CH
2
CH
2
CH
2
or CH
2
CH
2
NHCH
2
CH
2
CH
2
, m is an integer of 1 to 4, and n is equal to 2 or 3. However, this compound fails to take full advantage of the perfluoropolyether group because the perfluoropolyether moiety is as short as 2 to 5 monomeric units of hexafluoropropylene oxide (HFPO).
Also JP-A 58-122979 discloses a compound of the following formula (4) as a water and oil repellant applicable to a glass surface.
Herein, Rf is a polyfluoroalkyl group of 1 to 20 carbon atoms which may contain at least one ether bond, R
1
is hydrogen or lower alkyl, A is alkylene, X is —CON(R
2
)—Q— or —SO
2
N(R
2
)—Q— (wherein R
2
is lower alkyl and Q is a divalent organic group), Z is lower alkyl, Y is halogen, alkoxy or R
3
COO— (wherein R
3
is hydrogen or lower alkyl), n is an integer of 0 or 1, a is an integer of 1 to 3, and b is an integer of 0, 1 or 2. However, this compound is not satisfactory because the number of carbon atoms in the fluorinated group is as small as 1 to 20.
The present inventors previously proposed a perfluoropolyether of the following formula (5) in JP-A 11-29585.
Herein, X is a hydrolyzable group, R
1
is lower alkyl, R
2
is hydrogen or lower alkyl, Q is CH
2
CH
2
CH
2
or CH
2
CH
2
NHCH
2
CH
2
CH
2
, m is an integer of 6 to 50, n is equal to 2 or 3, and x and y each are an integer of 1 to 3. Because of good water and oil repellency, anti-staining properties, chemical resistance, lubricity, and parting properties, this perfluoropolyether-modified aminosilane can be utilized as a surface treating agent by coating onto surfaces of various substrates. However, the compound is not regarded satisfactory in performance to form a coat because the content (wt %) of hydrolyzable groups per molecule is low and consequently, curing takes a time. In particular, since many tall buildings are constructed in the recent decades, the demand for the technology for imparting “stain resistance” or “ease of stain removal” for keeping glazing maintenance-free is increasing. There is a desire to have a material meeting such a demand.
SUMMARY OF THE INVENTION
We have found that a novel perfluoropolyether-modified aminosilane of the following general formula (1) obtained by a method to be described later has improved water and oil repellency, anti-staining, chemical resistance, lubricity and parting properties. It can be used as a surface treating agent by coating to surfaces of various substrates. It cures into a coat which firmly bonds to a substrate so that the coat may sustain its effect over a long period of time.
Herein X
1
and X
2
each are a hydrolyzable group, R
1
and R
2
each are a monovalent hydrocarbon group of 1 to 6 carbon atoms, Q
1
and Q
2
each are a divalent organic group, m is an integer of 6 to 50, n is equal to 2 or 3, x and y each are an integer of 1 to 3.
The perfluoropolyether-modified aminosilane of formula (1) serving as a main component of the surface treating agent contains an amide linkage. The amide linkage is known effective for the efficient orientation of modifying fluorine groups to the substrate surface. In this regard too, the surface treating agent of the invention is more effective than prior art agents.
Because of the inclusion of two hydrolyzable silyl groups, the perfluoropolyether-modified aminosilane of formula (1) is more reactive than the above-mentioned aminosilane of formula (4) and improved in cure and film formability.
Accordingly, the invention provides a novel perfluoropolyether-modified aminosilane of formula (1); a surface treating agent primarily comprising the perfluoropolyether-modified aminosilane and/or a partial hydrolytic condensate thereof; and an article having on its surface a cured coating primarily comprising the perfluoropolyether-modified aminosilane and/or a partial hydrolytic condensate thereof.
REFERENCES:
patent: 58-122979 (1983-07-01), None
patent: 58-167597 (1983-10-01), None
patent: 11-29585 (1999-02-01), None
English Abstract of JP 58-167597.
English Abstract of JP 58-122979.
English Abstract of 11-29585.
Kishita Hirofumi
Yamaguchi Hiromasa
Yamaguchi Kouichi
Millen White Zelano & Branigan P.C.
Nakarani D. S.
Shin-Etsu Chemical Co. , Ltd.
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