Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2003-05-12
2004-09-28
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S028000, C428S447000, C427S387000
Reexamination Certificate
active
06797795
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a polymeric coating which inhibits the adhesion of ice to the surface of an object. The invention further relates to the composition and method of making a polysiloxane(amide-ureide) which provides a durable, long-lasting, anti-ice coating when applied to a substrate.
BACKGROUND OF THE INVENTION
The everyday buildup of ice upon the surfaces of mechanical, physical, and natural objects is a familiar annoyance, and quite often a safety hazard. The slick layers of ice that form on highways, driveways, and walkways make transportation difficult. The masses of ice that accumulate within or upon industrial, agricultural, or other mechanical equipment make operation of the equipment difficult or impossible. And, the weight of ice that weighs upon power lines, buildings, and signs often causes damage to those structures.
Ice accumulation upon vehicles, such as air or marine vehicles, poses a challenging problem. For example, ships traveling in the arctic and other cold climates may have ice form thereon, thereby disadvantageously increasing the weight and decreasing the maneuverability of the ships.
Buildup of ice upon the wings and components of an aircraft is of particular concern. The lift generated by the wings, and thus the ability of the aircraft to become and remain airborne, is dependent on the shape of the wings. Even a small accumulation of ice upon the surface of the wings can significantly increase drag and dramatically reduce lift. Further, ice buildup along control surfaces of the aircraft can impede the movement of those surfaces and prevent proper control of the aircraft.
There are a large variety of techniques used to control the buildup of ice upon the wings and other surfaces of aircraft. For instance, the aircraft may be deiced before takeoff by radiant heat energy or by application of a chemical spray which melts the ice from the wings. Such deicing sprays are environmental hazards. The ritual of deicing is well known to airline passengers traveling through cold environments.
Another method of deicing aircraft includes providing flexible pneumatic coverings (bladders) along the leading edges of the wings, and supplying bursts of air or fluid to expand the flexible coverings to break away any overlying ice. Similarly, bleeding air from the aircraft engine and routing the heated air to the surface of the wing heats the wing and melts the ice. Finally, ice may be removed from the wing by providing high-current pulses of electricity to a solenoid disposed within the wing which causes the wing to vibrate, fracturing any accumulated ice.
Although the previously mentioned methods of ice removal are generally effective, they require the continuous supply of air, chemicals, or electrical power in order to rid the wing of its burden. It would be preferred, of course, to prevent the accumulation of ice in the first place, but past attempts to develop practical passive methods of ice prevention have failed.
One would expect that known non-stick coatings would be able to prevent ice from adhering to the surfaces which they coat. In fact, aluminum surfaces coated with a polytetrafluoroethylene material exhibit a zero break force between the ice and the polytetrafluoroethylene coating. However, upon repeated freezing, the favorable properties exhibited by polytetrafluoroethylene and similar coatings degrade, resulting in a coating with little or no anti-icing capacity.
What is needed is a durable surface coating with long lasting anti-icing and/or de-icing properties which does not require the continuous supply of air, chemicals, or electrical power in order to rid a surface of ice or prevent ice from forming upon the surface. What is further needed is a surface coating that may be easily applied to the surface, especially to an aircraft, and which retains its functionality under a variety of environmental conditions, such as those typically encountered by a commercial or military aircraft. What is further needed is a method of applying the surface coating to at least a portion of a vehicle, such as an aircraft.
SUMMARY OF THE INVENTION
The invention is a polysiloxane(amide-ureide) coating capable of inhibiting the accumulation of ice upon the surface of a substrate, a process of producing the polysiloxane(amide-ureide), and a method of coating vehicles, particularly aircraft, with the polysiloxane(amide-ureide) coating. The polysiloxane(amide-ureide) forms a durable, long lasting, anti-ice coating when employed upon a substrate. When coated upon a substrate, the polysiloxane(amide-ureide) coating disrupts bonding between the ice and the coated substrate. Moreover, when ice does form, the coating disrupts the hydrogen bonding between the ice and the coated surface, thereby diminishing the ability of the ice to adhere to the surface. The ability of the coating to adhere to surfaces, and the ability of the coating to inhibit the formation of ice upon coated surfaces, makes the polysiloxane(amide-ureide) particularly useful for inhibiting the formation of ice on aircraft or other vehicles. The polysiloxane(amide-ureide) has the general formula:
wherein
R
1
and R
2
are independently selected from the group consisting of C
1
to C
10
alkyls, aryls, and polyaryls;
R
3
and R
4
are independently selected from the group consisting of hydrogen, C
1
to C
6
alkyls, aryls, C
3
to C
6
cycloaliphatics, and C
3
to C
6
heterocycles;
A
1
and A
2
are independently selected from the group consisting of hydrogen, C
1
to C
6
alkyls, aryls, polyaryls, C
3
to C
6
cycloaliphatics, and C
3
to C
6
heterocycles, and are preferably methyl;
wherein the alkyls may be linear or branched, saturated or unsaturated, halogenated or non-halogenated; aryls are preferably selected from C
6
, C
10
, and C
14
aryls and may be substituted or non-substituted, including alkylaryls and halogenated aryls; polyaryls are two or more aryls linked by at least one carbon-carbon bond and are preferably selected from biphenyl and terphenyl; cycloaliphatics may be saturated or unsaturated, halogenated or non-halogenated; heterocycles may be saturated or unsaturated, halogenated or non-halogenated; and alkylaryls may be linear or branched, saturated or unsaturated, halogenated or non-halogenated;
x is a number from 1 to 1000, preferably between about 200 and 500; and,
Y is selected from a substituted dicarboxyl residue and a diisocyanate residue wherein preferably about 40% to about 60% of the Y component within the polymer is the substituted dicarboxyl residue and the remaining portion of the Y component within the polymer is the diisocyanate residue, and wherein preferably greater than about 50% of the Y components are non-linear. It is the combination of both the dicarboxyl residues and the diisocyanate residues in the same polymer backbone that gives the desirable properties relative to interchain strength and ice inhibiting properties.
A preferred polysiloxane(amide-ureide) is represented by the formula:
wherein each of R
1
, R
2
, A
1
, A
2
, R
3
, R
4
, and x are as defined above, and Z is a dicarboxyl residue and CYAN is a non-linear diisocyanate residue.
The polysiloxane(amide-ureide) is formed by reacting a diamine-terminated polysiloxane, a halide substituted dicarboxylic acid, and a diisocyanate. The beginning diamine-terminated polysiloxane has the general formula:
wherein R
1
, R
2
, R
3
, R
4
, A
1
, A
2
, and x are as defined above.
The halide substituted dicarboxylic acid is a low molecular weight &agr;,&ohgr;-dicarboxlic acid wherein the hydroxyl from each carboxylic acid component has been replaced with a halide constituent, typically chloride, and where the dicarboxylic acid may be as long as a 10 carbon dicarboxylic acid. At least a portion of the substituted dicarboxylic acids are preferably selected from unsaturated acids, such as fumaryl, succinyl, phthalyl, terephthalyl and maleyl halides, and more preferably fumaryl chlorides and maleyl chlorides.
To prepare the preferred polymer, excess amine-terminated polysiloxane is first reacted w
Alston & Bird LLP
Moore Margaret G.
The Boeing Company
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