CA2264882A1 - De-icing agent - Google Patents

Abstract

Disclosed is a composition designed to lower the freezing point of water in particular in order to prevent the formation of ice. The composition contains a thickener, in addition to alcohols that are traditionally known to lower freezing points, in order to inhibit, at least, composition run-off from sloping or vertical surfaces such as car windows, aircraft surfaces and the like. The composition also contains a hydroscopic additive and/or a short-chain aliphatic monovalent alcohol in order to form, on the one hand, a film on at least the surface which is to be de-iced and on the other hand, to facilitate removal of the composition by means of water, for example, after de-icing.

Description

l01520253035CA 02264882 1999-03-05Deicing agentThe present invention relates to a compositionfor reducing the freezing point, in particular ofwater, or for preventing ice formation and an agent forin heatdeicing automobile windows, cooling elementspumps and wing profiles in aircraft.The problem arises during the winter months inthat automobile windows become coated with iceovernight iJ1 the case <3f automobiles standing jJ1 theopen air and thus necessitate troublesome scraping ofthe ice layer in order to ensure adequate vision duringdriving. In addition, the phenomenon of freezingatmospheric precipitation is frequently observed inCentral Europe during the winter months. Thisphenomenon is very frequently observed on automobilewindows in the form of an opaque, matt ice layer havinga thickness in the submillimeter range. The ice layersmentioned typically form on cold surfaces in vehiclesnecessitate mechanicalparked in the open air andremoval, chemical reduction of the freezing" point orheating up of the cold surface for removal of the icelayer or of the hindrance to vision. Owing to the lowambient temperatures or insufficient technical aids,the layer is often removed only in places and/orinsufficientlyf This leads to a Tundrance of visionand an increase in the potential danger when vehiclesare used.As a rule, water/glycol—based deicing agentsThe work thusis troublesome and furthermore,are used to remove the ice layers.necessitated at verylow temperatures, it takes a timerelatively longbefore the ice layer can be removed at least so that itit would beagents at ais possible to drive off. In principle,applysubstantially earlier time toadvantageous to such deicingthe automobile window,but as a rule the water/glycol solution flows away andl01520253035CA 02264882 1999-03-052the desired effect is therefore not achieved.For this reason, a number of patents haveproposed adding a thickener to the deicing agent toprevent the deicing agent from flowing away and henceto enable the action time to be prolonged. The aim isto enable the deicing agent to be applied to anautomobile window, for example, as early as theprevious evening in order to prevent the formation of.an ice layer from the outset. This would make itpossible to clear the automobile windows with littleeffort,possible to drive away quickly.for example on the next morning, so that it isThus, EP 360 183, EP 586 127, EP 678 565,EP 769 541, DE 19 40 825 and US 5 389 276 proposeadding a polymeric acrylic—based thickener to thewater/glycol—based deicing agent. WO 94/25538 proposes,as a thickener, a poly(N—vinylpyrrolidine) or acrosslinked maleic anhydride/methyl vinyl ethercopolymer, while EP 257 720 proposes, as a thickener,natural or synthetic rubber, cellulose ether,carboxymethylcellulose and hydroxyethylcellulose.EP 743 305 in turn proposes a polyetheramide which isFinally, DE 31 42 059proposes cellulose derivatives as thickeners.suitable as a thickener.However, all deicing agents proposed in theprior art have the major disadvantage that, on the onehand,filfll formation,the relatively high viscosity results in poorso that, for example, an automobilewindow or even larger surfaces to be deiced are nevercompletely "coated" by the deicing agent.lead toviscosities that the problem now is no longer the iceitself,In addition,at low temperatures, thickeners such highformation but the deicing agent which canscarcely be removed. Finally, as a rule the proposeddeicing agentswithcause smears and can be removed onlyeffort.necessary in some cases to remove these deicing agentsconsiderable cleaning Thus, it isl0l520253035CA 02264882 1999-03-05with hot water and solvents, which is certainly not anadvantageous procedure.It is therefore an object of the presentinvention to propose a process and an agent by means ofwhich the above—mentioned problems can be solved in avery simple manner and by means of which the removal ofan ice layer from, for example, an ice—covered glasspane can be effected in a very simple manner.According to the invention, the object proposedis achieved by means of composition and a processaccording to the wording of claim 1 and of claim 12,respectively.A composition and an agent for reducing thepoint, in water, and,freezing particular ofrespectively, for deicing are proposed, which, inaddition to the generally customary known constituentsin such substances, such as, for example, glycols,additionally contains a thickener which at leastinhibits flowing away of the composition or of thewhichaccording to theagent from. slanting or perpendicular surfaces,composition furthermore contains,invention, additionally a hygroscopic additive and/or ashort—chain aliphatic monohydric alcohol.The thickener may comprise, for example,high whichprevent the composition from flowing away on slantingrelatively molecular weight substancesor perpendicular surfaces, such as, for example,carboxymethylcellulose, carboxymethylcellulosederivatives, polyacrylates, polymethacrylates,polycarboxylic acids, polyethers, polyamides,alginates, gum arabic, etc.Also suitable as thickeners are the so—calledthixotropic agents, which are known to greatly increasethe viscosity of liquids which per se have a relativelylow viscosity when they are in the so~called reststate. Such thixotropic agents may be, for example,bentonite, kaolin, alginic acid, silicon compounds orl0l520253035CA 02264882 1999-03-05metal oxide gels.Compared with. the deicing agents proposed inthe prior art, the addition of hygroscopic substances,such as, for example, glycerol, pentaerythritol orsorbitol has the great advantage that the deicing agenthas a certain affinity to water and the viscosity canreduced by adding small amounts ofthus be rapidlyThus, even after a long residence time on thedeiced, thewater.surface to be deicing agent can berelatively easily removed by adding water.Particularly in the case of automobile windows, it isthus possible to remove the deicing agent by operatingthe windshield wipers, with the result that no greasyor oily surface remains behind on the pane and henceunobstructed vision is ensured.The surface endangered by icing is sprayedwhile still in the warm state, preferably at atemperature above freezing point, with the compositionas a preventive measure. The composition forms acoating which is preferably, but not necessarily,continuous on the treated surface. The composition ispreferably a mixture of alcohol, organic solvents, theabove~mentioned thickeners, corrosion inhibitors and,for extreme temperatures, of salts. Low—viscosity,short—chain aliphatic, monohydric alcohols arepreferably" used. These alcohols in turn reduce theviscosity of ‘the deicing agent at least during theapplication, which alcohols then evaporate,result of thefor exampleas a relatively low boiling point.hand thepreferably continuous coating is permitted and,other hand,Consequently, on the one formation of aon thethe application. is simplified Eur the lowviscosity. The composition reduces the freezing point,such aslike, and thussurface. Thefor example of the atmospheric precipitation,freezing rain, dew, snow and theprevents ice formation on the wetatmospheric precipitate forms on the surface with the101520253035CA 02264882 1999-03-055composition a gel—like mixture which can easily beremoved mechanically. In the case of surfaces treatedonly in places or of continuous wetting of the coldsurface, the composition is distributed by themechanical action. over areas which. have :not been. wetand remove the ice layer by lowering the freezingpoint. The action of the substance is substantial evenin the case of only partial wetting of a cold surface,since the compact outer layer is partially broken upand better attack areas thus form for the mechanicalremoval of the layer. The composition or substance canlikewise be applied to surfaces which are alreadycovered xuith ice, in the same way as a conventionaldeicing agent.For removing the composition proposed accordingto the invention, in particular when, on application,said composition contains the above—mentioned proposed,short—chain, aliphatic, monohydric alcohols, it isadvantageous once again to apply water to which thesame or an analogous alcohol has been added, in orderonce again to reduce the viscosity of the compositionto enable the surface to be rapidly cleaned. Theaddition of the alcohol makes it possible to clean thesurface rapidly and. without smearing and to free itfrom ice.Possible examples of the use of the compositiondefined according to the invention are, for example,— the prevention of icing of an automobile windowduring the winter months,— the prevention of icing of cooling elements in heatpumps or compressors and— the deicing of wing profiles in aircraft or thekeeping of said wing profiles free from ice.The composition cxr substance according tn) theinvention can be sprayed, atomized, brushed on orapplied by an immersion method. Potential applicationforms are aerosol cans, spray bottles, tubes and the101520253035CA 02264882 1999-03-056like for the retail trade. The following substancesare particularly suitable as constituents for thecompositions according to the invention for reducingthe freezing point or for keeping surfaces ice—free:1. As thickeners:High molecular weight substances which prevent theproduct from flowing away on slanting or perpendicularsurfaces, such as— carboxymethylcellulose,— carboxymethylcellulose derivatives,— polyacrylates,— polymethacrylates— polycarboxylic acids,— polyethers,— polyamides,— alginates,— gum arabic, etc.In general, thixotropic agents usually used inthe paint industry, such as, for example, bentonite,kaolin, alginic acid, silicon oxide compounds and metaloxide gels, are also suitable as thickeners.2. As alcohols:All alcohols usually used in deicing agents cangenerally be employed. Short—chain, monohydricalcohols having up to six: C atoms, such as ethanol,isopropanol, n-propanol, l—butanol, 2—butanol (sec-butyl alcohol), 2—methyl—2—propanol (tert-butylalcohol), etc., are preferably used.3. Suitable organic solvents and suitable freezingpoint depressants are those from the group consistingof the short—chain diols (glycols), such. as ethyleneglycol, propylene glycol, l,3—butanediol, etc., and/orglycol ethers having the general formula R—O-(CH2)n-O—R[sic], such as ethylene glycol menoethyl [sic] ether,ethylene glycol monopropyl ether, ethylene glycolmonobutyl ether, diethylene glycol monobutyl ether,ethylene glycol diethyl ether and/or diol esters1015202530CA 02264882 1999-03-057(glycol ester), prepared hwy esterification <3f one orboth hydroxyl groups, such as ethylene glycol monobutylether acetate, ethylene glycol monomethyl etheracetate, propylene glycol monomethyl ether acetate,etc.4. Salts: Suitable salts, especially for use atextremely low temperatures, are inorganic salts, suchas sodium chloride, potassium chloride, sodium sulfate,sodium phosphate, etc.5. Anticorrosion agents: All known corrosion—inhibitingor corrosion—preventing substances which as a rule areused for preventing corrosion on bodywork, such asorganic bases, basic salts, etc., are suitable.6. Hygroscopic additives: Glycerol, pentaerythritol,sorbitol.The above—mentioned examples of ea compositiondefinedproposals which can be extended as desired.according to the invention are of courseWhat isessential to the invention is that an agent is proposedfor reducing the freezing point or for keeping asurface ice—free, which agent is based essentially on aconventional composition whichadditionally contains a thickener which prevents thedeicingdeicing howeveragent from flowing away on slanting orperpendicular surfaces and a additiveand/or a short-chain aliphatic monohydric alcohol.hygroscopicThe invention is to be explained in more detailbelow with reference to the following Example and theaction of the composition proposed according to theinvention will be further confirmed by means of a testby the Swiss National Material Testing and ResearchInstitute.A deicing agent of the following compositionwas subjected to the test:101520253035CA 02264882 1999-03-058Water: 39.8% by weightIsopropyl alcohol: 20% by weightGlycol: 20% by weightSorbitol: 10% by weightPropylene glycol: 10% by weightTriethanolamine: 0.1% by weightCarbomer (acrylic~based polymer): 0.1% by weightTotal 100% by weightFirst test:A cleaned, vertical, dry pane was sprayed withthe deicing agent at normal temperature and then cooledto minus 25°C and stored for 120 hours. The conditionof the pane was assessed visually at 24 hour intervalsand the removability of the deicing agent from the panewas tested with the aid of a rubber scraper.Result:After storage for 120 hours, the deicing agentcould be removed effortlessly with a rubber scraper.2nd test:A cleaned,vertical, dry pane was sprayed withthe deicing agent at normal temperature. A fine waterfilm was then additionally applied to the deicing agentThereafter,with a spray bottle. the pane was cooledto minus 25°C and stored for 48 hours. The conditionof the pane was assessed visually at 24 hour intervalsand the removability of the deicing agent from the panewas tested with the aid of a rubber scraper.Result:Condition of the paneafter storage for 24 hours: sprayed—on water anddeicing agent not frozen,after storage for 48 hours: sprayed—on water anddeicing agent not frozen.The applied coating had run slightly downwardin places. After storage for 48 hours,could bethe deicingagent effortlessly removed with a rubberl0152025CA 02264882 1999-03-05scraper.3rd test:Half of thesprayed with deicing agent at normal temperature, andthen the entire pane was washed over with water andcleaned, vertical dry pane wasthen cooled to minus 25°C. The condition of the paneand theremovability' of the deicing agent fron1 the pane waswas assessed visually at 24 hour intervalstested with the aid of a rubber scraper.Result:Condition of the pane half sprayed with deicingagent and distilled water after storage for 24 hours:not frozen.Condition of the pane half sprayed with deicingagent and distilled water after storage for 48 hours:not frozen.The applied coating had run downward in places.After storage for 48 hours, the deicing agent could beeffortlessly removed with a rubber scraper.pane half sprayeddistilled water after storage for 24 hours:after storage for 48 hours: frozen.AfterCondition of the withfrozen,storage for 48 hours, the water hadfrozen on the pane and could be removed with the rubberscraper only with a great deal of effort.(Extracts froH1 Test Report No. 128963 of theSwiss National Material Testing and Research InstituteEMPA, Larchenfeldstrasse 5, CH—9014 st. Gallen).

Claims (12)

claims:

1. A deicing agent for reducing the freezing point, in particular of water, or for preventing ice formation, containing, in addition to the generally customary known alcohols for freezing point depression, with the exception of glycerol, a thickener for at least inhibiting the flowing away of the composition on slanting or perpendicular surfaces, wherein a hygroscopic substance is provided as a further additive, this comprising glycerol, pentoaerythritol [sic], sorbitol and/or mixtures thereof.

2. The deicing agent as claimed in claim 1, wherein glycerol, pentoaerythritol [sic], sorbitol and/or mixtures thereof are provided as the hygroscopic substance.

3. The deicing agent as claimed in either of claims 1 and 2, wherein a high molecular weight substance is used as the thickener.

4. The deicing agent as claimed in any of claims 1 to 3, wherein carboxymethylcellulose, carboxymethyl-cellulose derivatives, polyacrylates, polymeth-acrylates, polycarboxylic acids, polyethers, polyamides, alginates and/or gum arabic is [sic] used as a thickener.

5. The deicing agent as claimed in either of claims 1 and 2, wherein a thixotropic agent is used as a thickener.

6. The deicing agent as claimed in any of claims 1, 2 and 5, wherein a bentonite, kaolin, an alginic acid, silicon oxide compound and/or a metal oxide gel is used.

7. The deicing agent as claimed in any of claims 1 to 6, wherein a short-chain, monohydric alcohol having up to six C atoms is used, such as ethanol, isopropyl alcohol, n-propanal [sic], 1-butanol, 2-butanol (sec-butyl alcohol), 2-methyl-2-propanol (tert-butyl alcohol).

8. The deicing agent as claimed in any of claims 1 to 7, wherein furthermore an organic solvent from the group consisting of the short-chain diols (glycols), such as ethylene glycol, propylene glycol, 1,3-butanediol and/or glycol ethers having the general formula R-O-(CH2)n-O-R [sic] is used.

9. The deicing agent as claimed in any of claims 1 to 8, wherein it furthermore contains an inorganic salt, such as sodium chloride, potassium chloride, sodium sulfate and/or sodium phosphate.

10. The deicing agent as claimed in any of claims 1 to 9, wherein it furthermore contains an anticorrosion agent, such as, for example, organic bases and/or basic salts.

11. The deicing agent as claimed in any of claims 1 to 10, wherein it has at least the following constituents:
from 30 to 50% by weight of water, from 10 to 30% by weight of isopropyl alcohol, from 10 to 30% by weight of glycol, from 5 to 20% by weight of glycerol or sorbitol, from 5 to 20% by weight of propylene glycol and up to 2% by weight of thickener, preferably based on polyacrylate or polyacrylic acid.

12. A process for keeping a surface, such as an automobile window, a cooling element in heat pumps or wing profiles in aircraft, very substantially free from ice, wherein a deicing agent as claimed in any of claims 1 to 11 is applied to the surface in danger of icing over, preferably in the still warm or dry state, which composition, owing to the thickener contained, does not flow away and thus reduces the freezing point of any atmospheric precipitation and consequently prevents formation of ice on the surface wet with the composition.