This invention pertains to ice release agents and more particularly to those which allow the facile removal of ice from non-horizontal surfaces.
The adhesion of bonding of ice to various substrates is a problem encountered by main in a large part of the world. Ice formation on automobile windshields, frozen food storage areas, ship superstructures, rolling rock, outdoor functional equipment, and the like has caused the expenditure of considerable time and funds.
A number of solutions to this problem have been suggested in the past including:
1. Methods that reduce or eliminate ice accumulations. PA1 2. Methods that melt or otherwise remove existing accumulations of ice. PA1 3. Methods that attempt to place an effective, permanent ice release coating on the surface of the substrate. PA1 4. Methods that attempt to place an effective, temporary ice release coating on the surface of the substrate. PA1 1. The film thickness on a nonhorizontal surface, such as a windshield is too thin to provide for effective reduction of ice adhesion. PA1 2. The evaporation rate of the formultion is too rapid to effect ice release other than for a short length of time after application. PA1 3. The composition is rapidly diluted with water as ice contacts the composition, further reducing its effectiveness. PA1 a. a mixture of an alkylene glycol having two or three carbon atoms and water in a glycol: water ratio of about 20:80 to about 90:10. PA1 b. about 0.05 to about 1.0 parts of crosslinked polyacrylic acid per 100 parts of (a); PA1 c. sufficient base to neutralize the crosslinked polyacrylic acid selected from the class consisting of alkali metal hydroxides, ammonium hydroxide, alkyl amines having 4 to 12 carbon atoms, alkanolamines having 2 to 12 carbon atoms and morpholine; and PA1 d. about 50 to about 200 parts of an alkanol, having one to three carbon atoms, per 100 parts of the combination of (a), (b) and (c).
None of these methods have proved to be a satisfactory solution to this problem. The last method, viz., use of temporary release agents appears to be the most practical and economical but has not been successful for a variety of reasons. For example, Georgal et al. (U.S. Pat. No. 3,362,909) teaches the use of a composition consisting cheifly of n-propanol, water and ethylene glycol. However this composition performs poorly as an ice release agent for the following reasons:
Goms (U.S. Pat. No. 2,812,264) discloses the use of a composition consisting of organic oils (such as peanut and/or cocoanut oil), aluminum stearates and a minor amount of propylene glycol for use of as an ice release agent for frozen food lockers. This composition has the drawback of high viscosity which requires that it be carefully wiped onto the surface of the substrate in sufficient thickness to assure ease of ice removal. Thus the difficulty in application of this composition has discouraged its use and affords erratic results depending upon the care taken in application. It is also undesirable because of the oily nature of the composition which complicates removal from the ice lockers during clean-up operations.
Ethylene glycol based ice release agents have been used to prevent bonding of ice to airport runways, parking lots, sidewalks and the like and are satisfactory for these horizontal surfaces. However these compositions do not perform effectively on non-horizontal surfaces because their low viscosity allows them to drain off the non-horizontal surfaces by gravity leaving an insufficient quantity of the agent behind to provide effective ice release.
The ideal ice release agent combines inconsistent and seemingly mutually exclusive properties, viz., a low viscosity and an ability to maintain a thick film on non-horizontal surfaces.
It is an object of this invention to provide effective ice release agents which can be easily applied to non-horizontal substrates.
It is another object to provide ice release agents which remain on the non-horizontal substrate surface after application for periods of up to several days before ice accumulation begins.
It is still another object of this invention to provide an ice release agent which is not reduced in effectiveness for long periods of time once ice accumulation has occurred on the non-horizontal substrate.
It is still another object to provide an ice release agent which can be readily removed from the non-horizontal substrate surface if desired.