CA2623126A1 - Anti-fog refrigeration door and method of making the same - Google Patents

Abstract

The energy-free refrigeration door of the present application provides a way to control condensation when the door of a refrigeration unit is opened by providing thermal insulation to the door with glass panels which have a low emissivity coating. The door includes a door frame housing and an insulating glass unit comprising inner, middle and outer sheets of glass. A first sealant assembly disposed around the periphery of the inner and middle sheets of glass forms a first chamber between the inner and middle sheets of glass. A second sealant assembly disposed around the periphery of the middle and outer sheets of glass forms a second chamber between the middle and outer sheets of glass.
A gas, such as krypton, air, or argon is held in the first and second chambers. The outer sheet of glass and inner sheet of glass each have an unexposed surface that faces the middle sheet of glass. A low emissivity coating is disposed on the unexposed surfaces of the inner and outer sheets of glass so that the glass door as a whole avoids formation of condensation on the outer surface of the outer sheet of the glass door, without the application of electricity to heat the door, while also providing the desired evaporation rate of condensation from the inner side of the inner sheet of the glass door. An anti-fog or anti-frost coating is included on a surface of one of the sheets of glass.

Description

ANTI-FOG REFRIGERATION DOOR AND
METHOD OF MAKING THE SAME
[0001] This application is a continuation-in-part of U.S. Application No.
11/229,835, filed September 20, 2005, which claiins beneflt of U.S.
Provisional Application No. 60/610,964, filed SepteinUer 20, 2004, and U.S. Provisional Application No. 60/700,308, filed July 19, 2005, all of wllich are hereby incorporated in their entireties into the present application.

Field of the Invention [0002] The present invention relates, generally, to refrigeration doors, insulated glass units, and refrigeration systelns, and, in particular, to an anti-fog or anti-frost energy-free refrigeration door providing condensation control, thermal insulation, and a desired ainount of visible transmittance. More particularly, the refrigeration door of the present invention achieves these desired characteristics through the application of a low-emissivity coating, without electrically heating the door and through the application of an anti-fog/anti-frost coating or film.
Throughout this application the tenn "refrigeration door" is meant to refer to a door used for freezers, refrigerators and sinlilar units and cabinets. In addition, for purposes of this application the tenn "energy-free" (as in energy-free refrigeration door) means that electricity is not applied to the glass to heat the glass. "Anti-fog" and "anti-frost"
refer to a coating or fllm which reduces or eliminates the clearing time for a refrigeration door, insulated glass unit (IGU), or other article described herein.
Baclc~round of the Invention [0003] All United States Patents and Patent Application Publications referred to herein are hereby incorporated by reference in their entireties. In the case of conflict, the present specification, including definitions, will control.

[0004] Refrigeration doors for commercial fieezers, refrigerators and the like are typically constructed of glass to allow the customer to view the products placed therein for sale without opening the door. However, when condensation forms on the glass (sometinies referred to as "fogging"), the customer is not able to see through the door to identify the products inside, which is undesirable from the standpoint of botli the custonzer and the store owner or retailer. The fonziation of frost presents similar problems.

[0005] Moisture condenses on the outside of the glass refrigeration door because the surface temperature of the outside of the glass is reduced below the ambient temperature in the store by the colder refrigerated interior of the freezer or refrigerator. When the ten-iperature of the surface of the glass drops below the dew point of the air in the store, moisttire condenses on the surface of the glass. In addition, when a door is opened in a humid environment, the innerinost sheet of glass, which foniis the inside of the door, is also monientarily exposed to the anlbient air of the store and condensation may fomz on the inside of the door as well. The condensation on the inside of the glass door also occurs Uecause the temperature of the inside of the glass door is below the dew point of the ainbient store air to which it is exposed.

[0006] As previously indicated, condensation on the glass door, which may become frost, prevents the customer from seeing the products for sale through the glass door. Consequently, wlien condensation or fiost is on the glass door, the customer must perfonil the unpleasant task of opening the refrigeration door to identif-y the contents inside, which is impractical in a store with a large number of freezers or refrigerators. Not only is opening every refrigeration door tedious and time consuming from the custonler's perspective, it is undesiraUle from the retailer's standpoint as well, since it significantly increases the energy consumption of the retailer's freezers and refrigerators, thereUy resulting in higher energy costs to the retailer.

[0007] There are various industiy performance standards which refrigeration doors are required to comply with in order to be acceptable. In the United States, much of the industry requires freezer doors (but not refrigerator doors) that prevent external condensation when used in an environment with an outside tenlperature of eighty degrees Fahrenheit (80F), an outside relative hun-iidity of sixty percent (60%), and an inside temperature of niinus forty degrees Falirenheit (-40F). Other countries have different requirements.

[0008] As is well luiown in the art, a typical refrigeration door is comprised of an insulating glass unit (IGU) housed in a door frame. The IGU in a refrigeration door is, typically, comprised of two or three sheets of glass sealed at their peripheral edges by a sealant assenibly, generally referred to as an edge seal. In an IGU

comprised of three sheets of glass, two insulating chamUers are formed between the three sheets of glass. In an IGU coniprised of two sheets of glass, a single insulating chamUer is fonned. Typically, IGUs for refrigerators are constructed of two sheets of glass, wliile IGUs for freezers employ three sheets of glass. Once sealed, the chamUers are often filled with an inert gas such as argon, lcrypton, or other suitable gas to irnprove the thermal perforrnance of the IGU.

[0009] Most conventional approaches to preventing or reducing condensation in a refrigeration door involve supplying energy to the door by including a conductive coating on one or more of the glass surfaces of the IGU for electrically heating the glass. The purpose of heating the glass is to maintain the temperature of the glass above the dew point of the wanner ambient air of the store. By heating the glass above the dew point, the undesirable condensation and frost are prevented from fonning on the glass in the door, providing a clear view through the glass to the interior of the refrigeration coinpartment.

[0010] In a door consisting of a three-paned IGU, an unexposed surface of one or two of the sheets of glass is coated with a conductive material. The conductive coating is connected to a power supply by two bus bars or other electrical connectors mounted on opposite edges of the glass. As current passes through the coating, the coating heats, thereby heating the glass sheet to provide a condensation-free surface.
The coating on the IGU of a refrigeration door is normally applied to the unexposed surface of tlie outermost glass sheet. However, because condensation sometimes forms on the inside of the imier slieet of glass, the unexposed surface of the innermost sheet of glass may also be coated for heating to prevent condensation.

[0011] There are nuinerous drawbacks and problems associated with these conventional heated refrigeration doors of the prior art. First, heating the door incurs an energy cost above and beyond the energy costs of the cooling system. In a standard size coinniercial fieezer, the additional cost to heat a freezer door is substantial - based on current electrical utility pricing, such additional costs can be $100 per year or more for each freezer. Considering tllat many stores utilize multiple freezers, with some supermarlcets and other food retailers utilizing liundreds of freezers, the cumulative energy costs associated with such heated freezer doors are significant.

[0012] Second, excess heat from conventional heated refiigeration doors will migrate to the refrigeration conipartlnent, creating an additional burden on the cooling system, wliich results in still greater energy costs. T11ird, if the power suppled to the door for heating is too low, is turned off, or is shut down due to a power outage, condensation and/or frost will form on the glass. If the power dissipation is too high, unnecessaly additional energy costs will be incurred. In order to reduce the occurrence of these problems, such heated glass doors often require precise control of the door heating system. In order to acliieve the necessaiy precise control of the door heating system, an electrical control system is required, which results in increased design and manufacturing costs, as well as substantial operational and maintenance costs.

[0013] Fourth, these electrically heated glass doors present a safety hazard to customers and a potential risk of liability and exposure to retailers and refrigeration system manufacturers. The voltage applied to the glass door coating is typically 115 volts AC. The shopping carts used by customers in stores are heavy and metal.
If the shopping cart strikes and breaks the glass door, electricity may be conducted tlirough the cart to the customer, wliich could cause serious injtiry or even death.

[0014] U.S. Patent No. 5,852,284 and No. 6,148,563 disclose applying a voltage to a glass coated with a conductive coating (which may be a low emissivity coating) to control the formation of condensation on the outer surface of the glass door. The conductive coating, such as a low emissivity coating, provides a resistance to the electricity, which produces heat, while also providing desirable thermal characteristics. However, the refrigeration doors disclosed in these patents suffer fiom the previously described drawbacks and problems associated witli all electrically heated refrigeration doors. Glass units, doors, refrigeration uiiits and the lilce are also described in U.S. Patent Nos. 6,367,223, 6,606,832, and 6,606,833, and in U.S.
Patent Application Publication Nos. US2003/0062813 and US2003/197449. As indicated, these and other U.S. Patents and applications are hereby incorporated by reference in their entireties into this application.

[0015] In addition to being used for conductivity, such low emissivity coatings have been einployed as anotlier means for reducing condensation on refrigeration doors. Specifically, one method of increasing the insulating value of glass (the "R
value"), and reducing the loss of heat froni the refrigeration compartinent, is to apply a low emissivity (low E) coating to the glass. A low E coating is a microscopically thin, virttially invisible metal or metallic oxide layer(s) deposited on a glass surface to reduce the emissivity by suppressing radiative heat-flow through the glass.

Emissivity is the ratio of radiation eniitted by a black body or a surface and the tlieoretical radiation predicted by Planck's law. The tenn emissivity is used to refer to emissivity values measured in the infrared range by the Ainerican Society for Testing and Materials (ASTM) standards. Eniissivity is measured using radiometric measurements and reported as hemispherical emissivity and noi7nal emissivity.
The emissivity indicates the percentage of long infrared wavelength radiation emitted by the coating. A lower emissivity indicates that less heat will be transmitted through the glass. Consequently, the emissivity of a sheet of glass or of an IGU impacts the insulating value of the glass or IGU as well as the heat conductivity (tlle "U
value") of the glass or IGU. The U value of a sheet of glass or of an IGU is the inverse of its R
value.

[0016] In a multi-pane IGU, the emissivity of the IGU, which is the combined emissivity of the sheets of the glass that forni the IGU, may be approxiinated by multiplying the emissivity of all the sheets of glass togetlier. For example, in a two-sheet IGU with each slzeet of glass having an emissivity of 0.5, the total emissivity would be 0.5 multiplied by 0.5 or 0.25.

[0017] While low E coatings have Ueen applied to IGUs used in refrigeration doors both with and without electrically heating the doors, such coatings and IGUs are not capable of controlling condensation and providing the required thermal insulation tluough the broad range of teinperatures and environments in wllich such refrigeration doors are utilized witliout applying electricity to heat the doors. More specifically, notwithstanding the use of such low E coatings, refrigeration doors that are not heated have failed to provide condensation control in applications in which the interior teniperature of the refrigeration comparlnient is substantially near or below freezing.

[0018] Moreover, typical anti-fog/anti-frost coatings, films, etc. and inethods of applying them suffer limitations as well. For exainple, the films can still permit the fonnation of water droplets, which appear as the fog and obscure vision. Also, the anti-fog properties are often lost after a brief water soalc or repeated cleanings.
Moreover, laiown anti-fog products that function by absorbing condensate can saturate and fail under very humid conditions, due at least in part to their higllly swollen state. Also, these products caii scratch or smudge easily, and are not sufficiently tolerant or resistant to coninion solvents. Furthei7nore, comnlon coating problems, such as drips, rans, trapped dust and chemical crazing can occur with typical anti-fog products.

[0019] Thus, notwithstanding the available electrically heated and low emissivity coated refrigeration doors and available anti-fog and anti-frost products such as films and coatings, there is a need for a refrigeration door: (1) that provides the necessaiy condensation control and thei-mal insulation over a broad range of temperatures and enviromiients; (2) witli the desired ainount of visible transmittance;
(3) that avoids unnecessaiy energy costs and undtie burden on the cooling system by eliminating the need for supplying electrical power to heat the door; (4) that does not require an expensive and cornplex electrical control system, thereby minimizing design, manufacturing, operation, and maintenance costs; and (5) that does not present a safety hazard to customers and a potential risk of liability and exposure to manufacturers and retailers, and that otlierwise overcomes or reduces the probleins described above.
SUMMARY OF THE INVENTION

[0020] An objective of the present invention is to overcome the deficiencies of the prior art described above by providing an energy-fiee refrigeration door with condensation control, thennal insulation, and a desired amount of visible transmittance.

[0021] Another objective of the present invention is to provide a refrigeration door that does not employ electrical energy in order to reduce condensation on the glass.

[0022] Anotlier objective of the present invention is to provide a refrigeration door that controls condensation and that does not transfer significant heat to the interior of the freezer or refrigerator, thereby further burdening the cooling system and increasing energy costs.

[0023] Still another objective of the present invention is to provide a refrigeration door with condensation control that is easier and more economical to manufacture, operate, and maintain than the prior art refrigeration doors and systems.

[0024] Yet another objective of the present invention is to provide a refiigeration door with condensation control that is easier to design, operate, and maintain.

[0025] Another objective of the present invention is to provide a method for malcing a refrigeration door with condensation control that does not use electricity to heat the glass to control the condensation.

[0026] Yet another objective of the present invention is to provide a refrigeration door witlz an emissivity of less than 0.04.

[0027] Still another objective of the present invention is to provide a refrigeration door with an emissivity of approximately 0.0025.

[0028] Yet another objective of the present invention is to provide a refrigeration door with a U value of less than 0.2 BTU/hr-sq ft-F.

[0029] Still another objective of the present invention is to provide a refrigeration door witli a U value of approximately 0.16 BTU/hr-sq ft-F.

[0030] Yet another objective of the present invention is to provide a refiigeration door with additional anti-fog and anti-fiost properties that reduce clearing time to zero or near zero.

[0031] Further objectives include providing an anti-fog or anti-frost coating or film for use in a refrigeration door, as well as refrigeration systems and IGU's that include such films on a substrate surface.

[0032] The present invention achieves these objectives and others by providing, irater alia, energy-free refrigeration doors, and methods for making the same. In an aspect, the invention comprises a door frame housing an insulating glass unit coinprising inner, middle and outer sheets of glass. A first sealant assembly disposed around the periphery of the imier and middle sheets of glass forms a first chamber between the inner and middle sheets of glass. A second sealant assenlUly disposed around the periphery of the middle and outer sheets of glass forniis a second chamber between the middle and outer sheets of glass. A gas, such as krypton, air, or argon is held in the first and second chambers. The outer sheet of glass and inner sheet of glass each have an unexposed surface that faces the middle sheet of glass. A
low emissivity coating is disposed on the tinexposed surfaces of the inner and outer sheets of glass so that the glass door as a whole has a U value that prevents fomzation of condensation on the outer surface of the outer slleet of the glass door, without the application of electricity to heat the door, wllile also providing the desired evaporation rate of condensation from the imier side of the inner sheet of the glass door.
An anti-fog/anti-fiost coating or film is disposed on a surface of one of the glass sheets, preferably the exposed surface of the imier sheet.

[0033] In an aspect, the invention also provides a novel anti-fog/anti-frost coating.

[0034] The anti-fog/anti-frost coating is usefiil in various applications, such as insulated glass units, including those having multiple panes, refrigeration and freezer doors for refrigerated and freezer display cases, automotive mirrors, particularly extenial mirrors, saunas, steam rooms, shower doors, ticket Uooth windows, batlirooni windows, bathrooxn mirrors, outside coolers and freezers that are exposed to high lnunidity or rain, and any other applications in wliich an anti-frost or anti-fog coating/film would be desired. Thus, although the anti-fog/anti-frost coatings of the present invention are preferably used in coiulection with energy fYee refrigeration and freezer doors, they are also well suited for a variety of other applications, including doors having energy applied thereto, such as electrically heated doors.

[0035] Further features and advantages of the present invention, as well as the stn.icture and operation of various embodiments of the present invention, are described in detail below witli reference to the accoinpanying drawings.

BRIEF DESCRIPTION OF THE DRA.WINGS

[0036] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various einbodiments of the present invention and, together with the description, fitrther serve to explain the principles of the invention and to enable a person slcilled in the pertinent art to make and use the invention. In the drawings, like reference numUers indicate identical or fiinctionally similar elements.

[0037] A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes Uetter understood by reference to the following detailed description when considered in connection with the acconipanying drawings, wherein:

[0038] FIG. 1 depicts a refrigeration system employing an embodiment in accordance with the present invention.

[0039] FIG. 2 depicts a refrigeration door according to the present invention.

[0040] FIG. 3 is an illustration of a partial cross-sectional view of a refrigeration door according to the present invention.

[0041] FIG. 4 is an illustration of a partial cross-sectional view of a refiigeration door according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] In the following description, for purposes of explanation and not linzitation, specific details are set fortli, such as particular coatings, coating processes, sheet and film tlziclcnesses, seal assemblies, nuniber of sheets, sheet spacings, and inethods for assembling the door, etc. in order to provide a thorough understanding of the present invention. Ilowever, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. Detailed descriptions of well-laiown coatings, coating processes, sealant assenlblies, and nzetliods for assenibling the door are omitted so as not to obscure the description of the present invention. For purposes of this description of the invention, terms such as extei7lal, intexnal, outer, and inner are descriptions from the perspective of the inside of the freezer or refrigerator coinpartinent as is evident fiom the figures.

[0043] Testing, as well as computer inodeling, has shown that a U value (the conductivity of transfer of heat througli the glass) of approximately 0.2 BTU/hr-sq ft-F is required for the refrigeration door to prevent condensation on the outside of the glass under the perfonnance requirements for the United States industry as described above. As discussed, however, when the door is opened, condensation may fonn on the inside of the inner sheet of glass of the door Uecause the temperature of the inner surface of the sheet is below the dew point of the more huinid ambient store air to which it is exposed. The condensation, however will dissipate once the door is closed as the moisture evaporates into the freezer or refrigerator compartment.

[0044] While the condensation is present on the inside of the door, the contents of the freezer or refrigerator are not visible through the door. Consequently, the speed of the evaporation, which determuies the lengtli of time during which the condensation is present (refened to as "clearing tiine"), is an important design criterion. The more heat that is transferred through the glass door to the irmer surface of the glass door, the faster the condensation on the inside of the door will evaporate.
However, increased heat transfer tluough the door also results in increased energy costs from the cooling system. Consequently, the optimal U value of the glass door will be driven by numerous factors including the difference between the outside and inside temperatures, the glass thicla-iess, the spacing, the gas(es) used in the chamber(s) of the IGU, the number of sheets, the spacer inaterial, the ambient 1-iumidity, the absoiption coefficient of the coating in the far infrared spectrum, as well as the desirable tinle for evaporation of the condensation. In addition, the costs associated with the selected components (i.e., the gas, the sealant assembly, the glass, etc.), the energy costs, and other factors are also design considerations. The preferred enzbodiment described below provides a U value of 0.16 BTU/hr-sq ft F that prevents condensation on the outside of the door, while permitting enougli heat to penetrate througli the door from the ambient extenial environment to allow condensation on the inside of the door to evaporate in a reasonable ainount of time. Some refrigeration system manufacturers require that the condensation evaporate witliin a few niinutes and others require evaporation within one minute. In altei7iate embodiments, the U-value may be substantially equal to or less than 0.16 BTU/hr-sq ft F. The time required for the condensation to evaporate will vaiy according to the ainount of tiune the door is open, the huinidity in the store, the refrigeration system coinpartment temperature, the refrigeration system contents, the heat transferred through the door (which is dependent on the U value), and other factors.

[0045] In an embodiment of the present invention, as shown in Figure 1, a refrigeration system 5 includes a plurality of transparent refrigeration doors 10 with each having a handle 11. As will be discussed in more detail below, each refrigeration door 10 includes an IGU 50 nlounted in a frame 55. The interior of the refrigeration system includes a plurality of shelves 6 for holding merchandise to be seen through the door. Referring to Figure 2, the refrigeration door 10 of the present emUodiment is lnounted to the opening of the refrigeration system with a hinge, wliich allows the door to open outwards.

[0046] As discussed above, the refrigeration door 10 includes an IGU 50 housed in a fraine 55. As shown in Figure 3, the IGU 50 is coinprised of an outer sheet of glass 60, a middle sheet of glass 65, and an imler sheet of glass 70.
The IGU
50 is housed in frame 55 and also includes a first sealant assembly 90 that extends around the periphery of the irmer surface 62 of the outer sheet 60 and the outer surface of the middle sheet 65 of glass to define a substantially hemietically sealed insulated outer chamUer 92. Sinlilarly, a second sealant assembly 95 extends around the periphery of the outer surface 72 of the inner sheet 70 and inner surface of the middle sheet 65 of glass to define a suUstantially hernnetically sealed insulated inner chamUer 94.

[0047] The outer surface 61 of the outer sheet of glass 60 is positioned adjacent the external anibient enviroiunent 7. In otller words, the outer surface 61 of the outer sheet of 60 is exposed to the environment in wllich the refrigerator or freezer resides.

The inner surface 62 of the outer sheet 60 fonns part of, and is exposed to, the outer chamber 92.

[0048] In this preferred exanlple embodiment, the outer sheet 60 is one eighth of an inch thick, tempered, and the inner surface 62 of the outer sheet 60 is coated with a low emissivity coating 63. Specifically, in this embodiment, the low E
coating is a sputter-coated low E coating that includes an ultra-hard titania as the base layer to ensure a high level of therinal performance and a high visible transmittance.
This particular sputter coated glass can be tempered after the coating and offers high visible light transmission without high levels of color tinting. The outer surface 61 of outer sheet 60 is not coated. In this embodiment, the outer sheet 60 may, for exainple, be (without limitation) a slieet of Comfort Ti-PS glass, one eighth of an inch thick, manufactured by AFG Industries, Inc. of Kingsport, Teniiessee, wliich has a low E
coating providing an emissivity of 0.05. As is well-lcnown in the art, the Comfort Ti-PS is cut to the appropriate size, tempered, and edged before being integrated into the IGU 50. The low-E glass referred to herein is not limited to the above specifically named products, but may be any suitable low E glass, including, without limitation, sputter coated and pyrolytic coated low E glass.

[0049] The middle sheet of glass 65 is positioned between the outer 60 and inner 70 sheets of glass and forms part of the outer chamber 92 and the iiuler chamber 94. The middle sheet 65 is spaced one half inch from the outer sheet 60 and inner sheet 70 and is a one eighth of an inch thick, uncoated, sheet of tempered glass.

[0050] The inner slieet of glass 70 is positioned adjacent the interior of the freezer or refi-igerating coinpartinent 9, with its imzer surface 71 exposed to the interior of the compartnzent 9. The outer surface 72 of the inner sheet 70 forms part of, and is exposed to, the iiuzer chamber 94. The outer surface 72 of the iimer sheet 70 of glass is also coated with a low emissivity coating 73. In this embodiment, the coating 73 on the outer surface 72 of the inner sheet 70 is the same as that described above with respect to the coating 63 of the inner surface 62 of the outer sheet 60. In preferred enibodiments, the inner surface 71 has an anti-fog or anti-frost coating or film 75 applied to it, which reduces the clearing time during operation of the unit significantly, preferably to virtually zero (i.e. no visible fogging occurs).

[0051] Preferred anti-fog coatings or films include those laiown in the art as Vistex@ and Visgard@ Anti-Fog Films from Film Specialties, Inc. Such films may include an optical adhesive on the reverse side for installation. Vistex, for exanzple, comprises a polymer cured on a clear polyester fihn wit11 an optically clear adliesive on the reverse side. Vistex and Visgard tt can be purchased on plastic film or as liquids. The films eliminate fogging in all temperature-lztuliidity conditions.
Moreover, fog and condensate foi7nation is prevented even wlien the refrigerator or freezer door has Ueen propped open for extended periods of time, such as during restoclcing. The anti-fog properties are not lost after a brief water soak or repeated cleanings, nor do the coatings sattuate or fail under very humid conditions, such as those products that fiinction by absorbing condensate. Preferred anti-fog films used in the present invention are lrydrophilic, so moisture sheets out invisibly on the coated surface, rather than fonning droplets which appear as fog and oUscure vision.
Moreover, prefelTed films are scratch resistant and include an acrylic adhesive on the reverse side. The adliesive is of a type typically used on solar control films aizd allows the film to be applied to any flat or cylindrical surface. The adhesive system can be pressure sensitive or detackified pressure sensitive, both optically clear.
Various film thicknesses can be used, and one of ordinary skill in the art will readily be able to detei.-inine a suitable thiclaless for the application needed. The above noted coatings or films have a thiclaiess of about 4 mil. The films can be installed on a glass surface with a squeegee. Preferred coating/film thiclalesses for other embodiments discussed herein range from about 4 microns to about 20 inicrons.
Films/coatings having a thickness of about 4 microns are suitable for mirrors.
For best anti-frost perforinance, films/coatings between about 10 and about 20 microns are preferred, witli 12 to 15 microns being particularly preferable.

[0052] Preferred films/coatings are permanent anti-fog or anti-frost fihns based on liydrophilic polymer teclulology. The anti-fog/anti-frost coating operates by reducing the surface tension of water causing the condensate to sheet out, thus eliminating fogging under all temperature and humidity conditions. Preferable coatings tolerate a great deal more handling abuse than most untreated plastics. Slight surface scratches that occur in the anti-fog film will actually heal themselves wlien exposed to moisture. Moreover, preferred coatings exliibit a high degree of chemical resistance and will withstand solvents such as isopropyl alcohol, toluene, or acetone, therefore protecting the suUstrate from solvent attack. Ordinary glass cleaners can be used wlien necessary.

[0053] Preferred films/coatings are insoluUle in water, and will not sinudge or dissolve when wet, in contrast to otlier anti-fog coatings known in the art.
The preferred films/coatings are cured under controlled conditions, thereUy eliininating common coating problems, such as drips, runs, trapped dust and chemical crazing.
Moreover, the films add scratch resistance and a measure of shatter resistance to the glass to which they are applied. The adlzesives will bond to glass or any plastic, even a hard surface treated to resist scratclles.

[0054] Witli some laiown anti-fog and anti-frost films/coatings suitable for use in embodiments of the present invention, a cured primer is applied to the glass prior to application of the anti-fog or anti-frost film. A typical coating, Visgard , publicly lalown and available from Film Specialties, Inc., as indicated above, contains a mixture ratio of 100:40 of "Part A" to "Part B" cliemicals. The Visgard@ Part A
component includes diacetone alcohol (46%), N-methyl Pyrrolidone (4%), t-butanol (4%), Cyclohexane (8%), 2,4-pentanedione (6%), and Aromatic 150 (2%). The Visgard@ Part B coniponent includes polyisocyanate (66%), free monoineric isocyanates (1%), xylene (11%), n-butyl acetate (11%), and toluene (11%). As indicated, the Visgard@ Part A and Pai-t B coniponents are readily available to the public. Furtherniore, lcliown films typically contain additional solvents, such as additional ainounts of diacetone alcohol and tertiary butyl alcohol, for diluting the mixture. Moreover, processes for mal:ing the lalown films often include the requirement of two separate coating steps and two curing cycles. Curing time, temperature, and methodology can have a significant impact on anti-fog and anti-frost properties. For example, over-curing will significantly diminish the properties.
Forced convection is the slowest method and more likely to result in over-curing a thin-slcin of the coating, causing damage to the anti-fog and/or anti-frost properties Radiant energy is a quick and effective metllod of avoiding over-curing.

[0055] Some suitable coatings/films and aspects thereof are described in U.S.
Patent Nos. 4,467,073, 5,262,475, and 5,877,254, and U.S. Patent Application PuUlication Nos. US2003/0205059 Al, U52005/0064101, US2005/0064173, and US2005/0100730, all of which are hereby incorporated by reference in their entireties into the present application. These and the other patents and applications and description provided herein, provide ample guidance to one of slcill in the art to readily practice the present invention.

[0056] The present invention also provides novel anti-fog and anti-frost coatings/films that exhibit improved properties over the above-noted and other known coatings/films. The invention ftirther provides novel processes for making and applying such improved coatings/filnis. It has been found surprisingly, for example, that a mixture of Part A to Part B chemicals (described above in comzection with Visgard @), in a ratio of about 100 units of Part A to about 25-45 units of Part B, yields improved anti-fog and anti-frost results over lciiown films. A lower aniount of the Part B component (which seives as a hardener) within the above range iinproves the anti-frost properties of the film while retainiiig scratch resistance.
Good anti-fog properties can be achieved with a much higher percentage of the Part B
component.
In preferred emUodiments, the ratio is about 100 units of Pai-t A component to about 30-33 units of Part B conzponent. In particularly preferred embodiments, the ratio is about 100 units Pai-t A to about 30 units Part B, [0057] It also has been found suiprisingly that eliminating the use of additional solvents, such as additional diacetone alcohol and tertiaiy butyl alcohol, (particularly eliminating additional diacetone alcohol) enhances anti-fog and/or anti-frost perfonnance. Elimination of such solvents eiihances anti-frost perfoi7nance in particular. However, adding at least one such solvent, tertiary butyl alcohol, has been found to not hinder anti-frost perfonnance. Furtlierinore, in embodiments of the present invention, the cured primer typically included in previously lcnown films has been eliminated by pre-treating the glass substrate with a silane, and adding a different silane to the anti-fog/anti-frost mix. For example, the silane pre-treatment can help the polymer coating adhere to the substrate under extreme chemical conditions or long tenn moisture soalcing. In preferred emUodiments, the silane added to the mixture is 3-glycidoxypropyl triniethoxysilane ("3-G"). Including this silane has Ueen surprisingly found to increase abrasion (i.e. scratcli) resistance, and to promote adhesion and weatheraUility. 3-glycidoxypropyl trimethoxysilane also does not promote yellowing of the film as do some silanes. In preferred enibodiments, the 3 -glycidoxypropyl trimethoxysilane is present in an amount of about 1% to about 8%, most preferably about 6%.

[0058] (3-glycydoxypropyl) trimethoxysilane provides a benefit in terms of moisture resistance. The anti-fog or anti-frost coating is tested in a"P-1 box," which is 140 F rain with higli UV. Without 3-G, the coating will last 2 or 3 days before there is some peeling in the P-1 box. In contrast, with 3-G, the coating typically will last more than 8 weeks, and exhiUit no peeling. This represents a 30 fold inlprovement over coatings laclcing 3-G. To calculate a preferred quantity of 3-G to use, the sum of the volumes of Part A and Part B chemicals is multiplied by 6%.

[0059] The addition of fiinctional silanes enables the use on a glass substrate of an anti-fog or anti-frost coating material designed for plastic. This is also a significant reason why otllers in the art often have been unsuccessful in introducing product with sufficient chemical and moisture resistance to damage. Other silane additives also can be used with similar effect. Moreover, otlier suitable additives and primers are those that can promote adhesion of uretliane to inorganic compounds, such as glass. These materials include, without limitation, polymers that have an affinity to glass.

[0060] The invention also provides novel processes for malcing and applying the above films. In an aspect, the invention provides methods in which coating steps can be reduced to a single coating witli a single curing cycle. Among other advantages, this reduces the opportLuiity for the dainaging effects of over-curing.
Furtherinore, in embodinients of the invention, the coating or film is applied with a curtain coater. Adjustinents are made to prevent excessively high Reynolds nunibers in the cuitain to avoid semi-turbulent and turbulent flow regimes. For example, in embodiments, a standard weir-type curtain coater can be modified to give the desired laminar flow. Such modifications can include limiting the size of the weir lip to avoid semi-turbulent flow regimes.

[0061] In alternate einbodiments, the substrate, preferably glass, can be pre-treated witli a silane (preferably Silquest A-1106 amino alkyl silicone) to promote wetting and adllesion. A special silane is applied by mixing about 1% or less of the silane in the rinse water of a glass washer. Such a process eliminates some of the additional steps required in prior known processes. The in-ipact of the ainino alkyl silicone wash in boosting adhesion and chemical resistance to peeling is substantial.
Without a pre-wash of amino allcyl silicone, the coating potentially can be removed by soalcing in acetone for about two minutes. Pre-washing the glass with amino alkyl silicone has been shown to prevent peeling for more than 3 weelcs in the acetone test.
This represents a 15,000 fold improvement. In preferred einbodiments of the present invention, approximately 3 ounces of amino allcyl silicone in about 75 gallons (or similar ratio) of wash water is used to achieve this effect. Therefore, while some anti-fog and anti-frost coatings or fihns are laiown, and caii be used in coinbination witli the other aspects of the invention described herein, the present invention also provides novel anti-frost and anti-fog coatings/films that exhibit iinproved characteristics over those previously seen in the art, and novel processes for malcing and applying tliem.

In emhodiments, the invention provides anti-fog and anti-frost films/coatings witll modified ratios of Part A and Part B chemicals (as referred to above) in the mix, and coatings/films that do not include certain typically used solvents. Moreover, in einbodiments of the present invention, the characteristics of the films can be enhanced by modifications to the curing cycle. The substrate can also be pre-txeated to promote wetting and adhesion.

[0062] Thus in an aspect, the invention provides polymer compositions which have anti-fogging and anti-frost-fonning properties upon drying or curing. In preferred embodiments, the compositions comprise a chemical mix ratio of about 100:30 Part A to Part B chemicals (described herein) and do not include solvents, dilutants, or cured primers that are applied to the glass suUstrate. In altei7late cnibodiments, the mix includes a silane, preferably 3-glycidoxypropyl trimethoxysilane. Preferred coinpositions promote scratch resistance, adhesion and weatherahility.

[0063] In anotlier aspect, the invention provides refrigeration doors comprising a substantially transparent substrate having an anti-fog or anti-fiost coating on at least a poi-tion thereof, the portion of thc substrate substantially not fogging or frosting when the portion has an initial surface temperature and is then exposed to a moist air ambient with a dewpoint temperattire equal to or greater than the surface temperature for a period of time. The surface temperature may be less than about 0 degrees C and the period of time may be up to 6 seconds or more. -[0064] The invention also provides a method of making a refrigeration door having a substantially transparent substrate, the method comprising fonning an anti-fog or anti-frost coating as described herein on at least a por-tion of the suhstrate wherein the suhstrate is part of a refrigeration door or is used to manufacture a refrigeration door. In an emUodiment, the metliod includes mixing Part A and Par-t B
chemicals to forn-i a mixttire, applying the mixture to at least a portion of the substrate and curing the substrate. The invention fiirther provides IGUs comprising a substrate having an anti-fog or anti-frost coating on at least a portion tliereof as described herein, refrigeration doors coinprising such an IGU, refrigeration systems comprising the refrigeration doors. Moreover, in fiu-tlier embodiments, thc invention provides a refrigerator door coinprising a substantially transparent substrate having on at least a portion thereof a coating which prevents the condensation of water thereon wlien said portion maintained at a teniperature of about -28 degrees C is exposed to an atinosphere at a temperature of about 25 degrees C for up to 12 seconds or more. The prevention of condensed droplets results in the prevention of the formation of light scattering fog or frost.

[0065] In the embodiment described in Figure 3, the inner sheet 70 may also, for exaniple, be, without limitation, a sheet of Comfort Ti-PS, one eighth of an inch thick, manufactured by AFG Industries, Inc., which has the described characteristics and coating.

[0066] In this exenlplified embodiinent, the chamUers 92 and 94 are both filled with air. In alternative embodiments, each chamber may be filled witli the same or a different gas and the chanzUers could be filled with krypton, argon, or other suitable gas.

[0067] The sheets 60, 65 are held apart by a first sealant assembly 90 which extends around the peripheiy of the sheets 60, 65 maintaining the glass slieets in parallel, spaced-apart relationship creating chamber 92 between the slieets 60, 65, wliile also sealing the chainUer 92 from the external environment. Likewise, the sheets 65, 70 are held apart by a second sealant assembly 95 wliich extends around the periphery of the sheets 65, 70 maintaining the glass sheets in parallel, spaced-apart relationship creating chamber 94 between the sheets 65, 70 wliile also sealing the chamUer 94 from the exteinal environment. The sealant assemblies 90, 95 maintain a one half inch space between the outer sheet 60 and middle sheet 65 and inner sheet 70 and middle sheet 65, respectively.

[0068] The sealant assemblies 90, 95 of the present einUodiment are preferably, wann edge seals. "Wann edge" is used to describe an insulating glass sealing assembly that reduces heat loss better than conventional aluminuni spacers and sealant coinbinations. Each of the sealant assemblies 90, 95 of this embodiment includes its own spacer and desiccant, wlzich replaces the need for a separate sealant, metallic spacer, and desiccant, and has a lieat transfer rate of 0.84 Btu/hr-ft-F
(sometimes referred to as K value). The sealant assemblies 90, 95 in this emUodiment are a coinposite extrusion containing a coinbination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim and a vapor barrier.
Suitable sealant assemblies of this type are manufacttued and sold by TniSeal Technologies of Beachwood, Ohio, under the name "Comfort Seal."

[0069] Referring to Figure 3, IGU 50 is shown. IGU 50 is comprised of glass sheets 60, 65, and 70 integrated by sealant assemblies 90 and 95. IGU 50 is installed in frame 55 in any suitable nzanner well-lulown to those skilled in the art.
The fiame 55 is made from extruded plastic or other suitable well-lcnown fiame materials, such as extTi.ided aluminum, fiber glass or other material. If, in any alternative enibodiment the frame 55 is fonned of aluminum or other material, the door may require heating along its edges to ensure condensation control around the edges of the door.

[0070] Referring to Figure 1, a refrigeration system 5 is shown. The door frame 55 is coupled to the refrigeration compartinent 8 in any suitable fashion as is well laiown in the art, such as a single door long hinge, multiple hinges, or in a slot for sliding the door open and closed. In addition, the frame may include a door handle 11 or other suitable actuating means as is appropriate for the application. The refrigeration system 5, of which the door 10 foi7ns a part, may be any system used for cooling a compartinent, such as that disclosed in U.S. Pat. No. 6,148,563, which is hereby incorporated herein by reference.

[0071] The above preferred emUodiment provides a refrigeration door with a U
value of 0.16 BTU/hr-sq ft-F (and einissivity of 0.0025), which has been found to be suitable for freezer door applications requiring the perfonnance standards identified above with respect to the United States industry. A U value of 0.16 BTU/hr-sq ft-F
pennits the refrigeration door to easily meet the required perfonnance standards, while also allowing enough heat to penetrate through the door with the external ambient enviromnent to evaporate condensation formed on the inside of the door in a reasonable time period. In addition, the preferred embodiment provides a visible light transmittance of sixty-six percent (66%). In the above preferred einUodiment, which includes an anti-fog/anti-frost coating or film as described, no fogging or frost fonnation is observed on the glass.

[0072] As an alteniative to the Comfort Ti-PS glass, other low E coated glass may be used, such as, for example, Comfort Ti-R, Comfort Ti-AC, Comfort Ti-RTC, and Comfort Ti-ACTC, all of which are available from AFG Industries, Inc., which like Comfort Ti-PS, are titania/silver based low E coated glass manufactured by AFG
Industries, Inc. Another suitable type of glass is Conlfort E2, which is coated with a pyrolytic process and is a fluorine doped tin oxide low E coated glass, one eightli of an inch thick, and which is manufactured by AFG Industries, Inc. Comfort E2 is suitable for sonze of the less stringent perforinance standards Uecause of its higher emissivity. The low-E glass referred to herein is not limited to the above specifically named products, but may be any suitable low E glass, including, witliout limitation, the above noted, and other sputter coated and pyrolytic coated low E glass.

[0073] The U value of the refrigeration door 10 is detennined by a number of design factors including the number of sheets of glass, the thiclaiess of the slieets, the emissivity of the IGU, the spacing between the sheets, and the gas in the chamber(s).
In the three pane refrigeration door 10 of the preferred emUodiment described above, the U value of 0.16 BTU/Iir-sq ft-F is acconiplished using air as the gas being held in the chambers, glass tliiclaiesses of one eighth of an inch on all sheets, one half inch spacing, and an IGU emissivity of 0.0025. However, each of these factors can be varied resulting in numerous pennutations of values that could be coinbined to provide the same U value. In addition, other applications may require a smaller or larger U value depending on the environment, costs constraints, and other requirements or considerations.

[0074] A number of computer simulations have been perfonned to detennine the U values of nunlerous IGUs for use in refrigeration doors 10 with a range of values of each of the various design parameters coinbined in different pennutations.
The table below includes the design parameters and corresponding calculated U
values for a number of three pane IGU configurations. In addition to the design parameters listed in Table 1 below, all of the three pane IGU U value calculations were conlputed with each pane being one eighth of an inch thick, and a total of two sides of the three panes being low E coated. Teinpering of the glass does not significaiztly affect the calculated perfonnance values. Moreover, the addition of the anti-fog/anti-frost coating or film in accordance with the invention does not significantly affect these values.

Spacing Gas in Type of Coating Emissivity of U value between Chambers IGU (Btu/lvr-sq ft-F) Sheets (inches) %2 air Ti-PS 0.0025 0.16 5/16 air Ti-PS 0.0025 0.22 %2 argon Ti-PS 0.0025 0.12 5/16 argon Ti-PS 0.0025 0.17 1/2 lnypton Ti-PS 0.0025 0.11 5/16 lciypton Ti-PS 0.0025 0.11 %2 air CE2 0.04 0.20 5/16 air CE2 0.04 0.26 1/2 argon CE2 0.04 0.17 5/16 argon CE2 0.04 0.21 %2 lcrypton CE2 0.04 0.15 5/16 lcrypton CE2 0.04 0.15 [0075] In each of the tables included herein, "Ti-PS" refers to the low E
coating of AFG Industries' Comfort Ti-PS glass and "CE2" refers to the low E
coating of AFG Industries' Comfort E2 glass, botli described above. In addition, the U values in the tables are calculated as "center of the glass" values, because the computer simulation does not have the capability to consider the sealant assenibly.
Consequently, there are no sealant asseinbly data or design criteria listed in the tables.

[0076] In an alternative two pane einhodiment of the present invention shown in Figure 4, the IGU 50 includes an outer sheet 60 and inner slieet 70 of glass, the frame 55, and a sealant assembly 90. In this two-pane embodiment, both the outer sheet 60 and imler sheet 70 are one eighth of an inch thick and include the sanie low E
coating as described in the first embodiment, which is titania based silver low E
coating. Again, Uoth the outer sheet 60 and iinier sheet 70 may, for example, be a sheet of Comfort Ti-PS glass, one eighth of an inch tllick, manufactlued by AFG
Industries, Inc. The coated sides of the sheets 60 and 70 are on the unexposed surfaces of the slzeets, sides 62 and 72, respectively, which fonn part of the chamber 92. In addition, the same sealant assembly 90 described above (the Comfort Seal) may be used and acts to provide a spacing of one half inch between the outer 60 and inner 70 sheets of glass. Again, the anti-fog/anti-frost coating or fihi175 is disposed on the exposed surface 71 of inner sheet 70.

[0077] Table 2 below includes design parameters and the corresponding calculated U values for a nunlber of two pane IGUs. In addition to the design parameters listed in the table below, all of the two pane calculations were computed witli each pane being one eightll of an inch thick, and a total of two sides of the two panes being low E coated. Tempering of the glass does not significantly effect the calculated perfonnance values, nor does addition of an anti-fog/anti-frost coating or film as described herein.

Spacing Gas in Chambers Type of Coating Emissivity of U value between IGU (Btu/hr-sq Sheets ft-F) (inches) '/2 air Ti-PS 0.0025 0.29 5/16 air Ti-PS 0.0025 0.36 %z argon Ti-PS 0.0025 0.23 5/16 argon Ti-PS 0.0025 0.28 1/2 lcrypton Ti-PS 0.0025 0.22 5/16 lcrypton Ti-PS 0.0025 0.20 %2 air CE2 0.04 0.32 5/16 air CE2 0.04 0.39 % argon CE2 0.04 0.27 5/16 argon CE2 0.04 0.31 1/2 la=ypton CE2 0.04 0.26 5/16 lcrypton CE2 0.04 0.24 [0078] In alternate embodiments, any suitable type of coating processes for the low-E coating may be employed including pyrolytic (e.g., as in the Comfort E2), which is often referred to as chemical vapor deposition (CVD), spray, and sputter coating (e.g., as in the Comfort Ti-PS). Furthermore, these processes may be applied using well-la-lown off-line or on-line manufacturing niethods as is suitable and appropriate for the quantity and type of production and process. Likewise, any suitable low E coating may be employed including silver based or fluorine doped tin oxide coating.

[0079] Although the enzbodiments described above include low E coatings on the unexposed surfaces of two sheets of glass, other embodiments of the present invention might include a low E coating applied to only one sheet of glass on either side, or on Uoth sides. Likewise, in otlier embodiments the middle sheet of glass (of a three pane embodiment) may include a low E coating on eitlier side (or botli sides) instead of, or in addition to, coatings on the inner sheet 70 and outer sheet 60 of glass.

[0080] In yet another three pane embodinlent, the inner sheet of glass 70 does not have a low E coating on either side of the sheet of glass 70. Lilcewise, in an alternative to the two sheet emUodiment described above, the low E coating is present on only one sheet, or on both sides of both sheets. In general, the nuinber of sheets that have the low E coating and the side (or sides) that have the coating is a design choice. The total emissivity of the IGU, wllich along with other factors detennines the U factor of the door, is more iniportant witll respect to the thennal perfomzance than wllich side or sides of which sheet(s) are coated. In addition, altliougll the emUodiments described herein have emissivities of less than or equal to 0.04 for refrigeration door applications, using a higli perfonnance gas (such as lcrypton) may enable an IGU with an emissivity of sliglitly more than 0.04 to provide the necessary condensation control in some circumstances.

[0081] In other embodin-ients, other sealant asseinblies may be employed including for example, an all-foam, non-metal assenzbly such as the Super Spacer, mamifactured by EdgeTech, Inc, which has a heat transfer rate of approximately 1.51 Btu/hr-ft-F. Anotlier suitable sealant assembly is the ThemloPlastic Spacersystem (TPS) manufactured by Lenhardt MaschinenUau GmbH, which has a heat transfer rate of approximately 1.73 Btu/hr-ft-F.

[0082] The spacing in the above disclosed embodiments is one half inch.
However, while the preferred spacing ranges between five sixteenths of an inch to one half inch, other embodiments of the invention may use spacings up to three quarters of an inch. In addition, while the above disclosed embodiments einploy glass one eightli of an inch thick that is tempered (except for the middle sheet), other embodinients may use untempered glass or tliiclaiesses that are greater tlian, or less than, one eiglitli of an inch.

[0083] The design parameters of an embodinlent of the present invention will be determined, in part, by the application or intended use of the embodiment.
More specifically, the exterior ambient teniperature, interior tenlperature, and exterior ambient liumidity (and associated dew point) are inlportant factors in determining the necessaiy U value for the design, which in turn, detenilines the design paraineters (type of glass, emissivity, number of slieets, gas, etc.).

[0084] The left five columns of Table 3 below provide a list of calculated U
values for various applications of the intended use and includes the exterior temperature, interior temperature, exterior humidity, and calculated dew point for each U value. In addition, the right three coh.imns of Table 3 provide an embodiment of the invention that will provide the necessary U value.

Calculated U Values for Various IGU Design Variables Environmental Parameters For Satisfyin IdentifiedU Value Exterior Interior U Value Dewpoint Maximum Glass (Two Spacing Gas In Temp Temp Deg Btu/ (Outside Relative Sheets) Inches Chambers Deg F F hr-sq ft-F Glass T) Deg Humidity F Percent 80 -40 0.19 64.9 60.1 Ti-PS 3/8 air 72 0 0.27 57.4 60 CE2 5/16 air 80 -40 0.15 67.6 66.0 CE2 3/8 lcrypton 80 -40 0.18 65.7 61.8 CE2 3/8 argon 80 -40 0.25 60.3 51.1 CE2 3/8 air 80 -40 0.16 67.3 65.3 CE2 %2 krypton 80 -40 0.17 66.5 63.5 CE2 1/2 argon 80 -40 0.20 64.1 58.5 CE2 %z air 80 -40 0.11 70.6 73.1 Ti-PS 3/8 krypton 80 -40 0.14 68.6 68.3 Ti-PS 3/8 argon 80 -40 0.19 65.0 60.3 Ti-PS 3/8 air 80 -40 0.12 70.2 72.1 Ti-PS 1/2 krypton 80 -40 0.13 69.4 70.2 Ti-PS % argon 80 -40 0.17 66.7 64.0 Ti-PS V2 air 72 -10 0.18 61.2 68.9 CE2 3/8 argon 72 0 0.18 62.1 71.1 CE2 3/8 argon 72 10 0.18 63.0 73.4 CE2 3/8 argon 70 0 0.18 60.3 71.4 CE2 3/8 argon 80 0 0.18 69.2 69.7 CE2 3/8 argon 90 0 0.18 78.1 68.3 CE2 3/8 argon 70 -20 0.21 55.5 60.1 CE2 3/8 air 86 -22 0.11 77.5 75.9 Ti-PS 3/8 lu-ypton 80 -40 0.19 65.0 60.3 CE1 %2 air 70 32 0.18 63.4 79.6 CE2 3/8 argon 80 32 0.18 72.2 77.2 CE2 3/8 argon 90 32 0.18 81.0 75.0 CE2 3/8 argon [0085] The design paranieters of Table 3 identify the type of glass (which is one eighth of an inch thiclc), the spacing between sheets, and the gas in the chamUers.
In addition, all of the IGUs of the Table 3 include a third, non-coated sheet of glass that is one eighth of an inch tliick, and that is disposed between the two sheets of glass identified in the taUle. CE1 in the Table 3 refers to Comfort El, which has an emissivity of 0.35 and is sold by AFG Industries, Inc.

[0086] In an aspect, therefore, the invention provides a refrigeration door adapted for use in a refrigerating compartnlent, the door comprising an inner sheet of glass including a first surface and a second surface, said first surface of said inner sheet being disposed adjacent the interior of the refrigerating compartment, an outer sheet of glass including a first surface and a second surface, said first surface of said outer sheet being disposed adj acent the exterior environment of the refrigerating compartment a middle sheet of glass disposed between said inner and outer sheets of glass, a first sealant assembly disposed around the periphery of said imier sheet of glass and said middle sheet of glass for maintaining said inner sheet and said middle sheet in spaced-apart relationship from each other, a second sealant assemUly disposed around the periphery of said middle sheet of glass and said outer sheet of glass for maintaining said middle sheet and said outer sheet in spaced-apart relationship from each other, a first low emissivity coating adjacent the second surface of said inner sheet of glass, a second low emissivity coating adjacent the second surface of said outer sheet of glass, said imier sheet, outer sheet, middle sheet, first sealant asseinUly, second sealant assenibly, and said first and second low emissivity coatings forming an insulating glass unit having a U value substantially preventing the foi7nation of condensation on said first surface of said outer sheet of glass without the application of electricity for heating said first surface of said outer sheet of glass, an anti-fog or anti-frost coating on a surface of the imier sheet, and a frame secured around the periphery of said insulating glass unit. The insulating glass unit can have a U value substantially equal to or less than 0.2 BTU/hr-sq ft-F.

[0087] The invention also provides a refrigeration door adapted for use in a refrigerating coinparlinent, the door comprising an inner sheet of glass including a first surface and a second surface, said first surface of said inner sheet being disposed adjacent the interior of the refrigerating compartinent, an outer sheet of glass including a first surface and a second surface, said first surface of said outer sheet being disposed adjacent the exterior environment of the refrigerating compartnient a middle sheet of glass disposed between said imier and outer slieets of glass, a first sealant assembly disposed around the peripheiy of said inner sheet of glass and said middle slieet of glass for maintaining said inner sheet and said middle sheet in spaced-apart relationship from each otlier, a second sealant asseinbly disposed around the periphery of said middle sheet of glass and said outer sheet of glass for maintaining said middle sheet and said outer sheet in spaced-apart relationship from each other, a first low emissivity coating adjacent the second surface of said inner sheet of glass, a second low emissivity coating adjacent the second surface of said outer sheet of glass, said inner sheet, outer sheet, middle sheet, first sealant asseinbly, second sealant assembly, and said first and second low emissivity coatings fonning an insulating glass unit having an emissivity equal to or less than 0.04 substantially preventing the fonnation of condensation on said first surface of said otiter sheet of glass without the application of electricity for heating said first surface of said outer sheet of glass, an anti-fog or anti-frost coating on a surface of the irmer sheet, and a frame secured around the periphery of said insulating glass unit.

[0088] - In enlbodinlents, the interior temperature of the refrigerating comparthnent is substantially equal to or less than minus twenty degrees Fahrenheit;
the temperature of the exterior environment is substantially equal to or greater than seventy degrees Fahrenheit; and the hunlidity in the exterior enviroimient is substantially equal to or greater than sixty percent, the first surface of the outer sheet of glass is substantially free of condensation and no fogging or frost fonnation occurs on the inner sheet.

[0089] In fiirther emUodiments, the interior temperature of the refrigerating compartiiient is suUstantially equal to or less than zero degrees Fahrenheit, the temperature of the exterior environment is substantially equal to or greater than seventy two degrees FahreiAieit, and the humidity in the ambient enviromnent is substantially equal to or greater than sixty percent, the first surface of the outer sheet of glass is substantially free of condensation and no fogging or frost fonnation occurs on the iiuler sheet.

[0090] The invention further provides refiigeration doors (and IGUs, and refrigeration systeins comprising them) having an outer surface and adapted for use in a refrigerating compartment, the door comprising a first sheet of glass, a second sheet of glass, a first sealant assenibly disposed around the periphery of the first sheet of glass and the second sheet of glass for maintaining the first sheet and second sheet in spaced-apart-relationship from each other, a first low enzissivity coating adjacent a surface of the first sheet or the second sheet of glass, the first sheet and second sheets of glass, the first sealant assemUly, and the first low emissivity coating forniing an insulating glass unit having a U value suUstantially equal to or less than 0.2 BTU/hr-sq ft-F, an anti-fog or anti-frost coating on a surface of one of the sheets and a frame secured around the periphery of the insulating glass unit.

[0091] The invention ftuther provides refrigeration doors (and IGUs, and refrigeration systems comprising them) having an outer surface and adapted for use in a refrigerating compartment, the door coniprising a first sheet of glass, a second sheet of glass, a first sealant assembly disposed around the periphery of the first sheet of glass and the second slleet of glass for maintaining tlie first sheet and second sheet in spaced-apart relationship from each other, a first low emissivity coating adjacent a surface of the first sheet or the second sheet of glass, the first sheet and second sheets of glass, the first sealant assembly, and the first low emissivity coating forniing an insulating glass unit having an emissivity equal to or less tllan 0.04 , an anti-fog or anti-frost coating on a surface of one of the sheets and a franie secured around the periphery of the insulating glass unit.

[0092] The invention also provides a method of manufactLiring a refrigeration door component having an outer surface, said metliod comprising the steps of providing a first sheet of glass; providing a second sheet of glass; providing a first low emissivity coating adjacent a surface of said first sheet of glass or said second sheet of glass; disposing a first sealant asseinbly around the periphery of said first slleet of glass and said second sheet of glass to maintain said first sheet and said second sheet in spaced-apart relationship from each other; providing an anti-fog or anti-frost coating on one of the sheets of glass; and wherein said first sheet of glass, said second slieet of glass, and said first sealant assembly fonn an insulating glass unit having a U
valtie substantially preventing the fonnation of condensation on the outer surface of the refrigeration door component without the application of electricity for heating the door conzponent and substantially preventing fog or frost fonnation on a surface of the conlponent. The insulating glass unit can have a U value substantially equal to or less than 0.2 BTU/hr-sq ft-F. In alternate embodiments, the metliod includes providing a third sheet of glass, which may include a low-E coating adjacent at least one of its surfaces; disposing a second sealant assembly disposed around the periphery of said second sheet of glass and said third of glass for inaintaining said second sheet and said third sheet in spaced-apart relationship from each other; and wherein said insulating glass unit fiirther includes said third sheet of glass and said second sealant assenibly.

[0093] The invention also provides a metllod of manufacturing a refrigeration door component having an outer surface, said nletliod comprising the steps of providing a first sheet of glass; providing a second sheet of glass; providing a first low emissivity coating adjacent a surface of said first sheet of glass or said second sheet of glass; disposing a first sealant assemhly around the pcripheiy of said first sheet of glass and said second sheet of glass to maintain said first sheet and said second sheet in spaced-apart relationship from each other; providing an anti-fog or anti-frost coating on one of the sheets of glass; and wherein said first sheet of glass, said second sheet of glass, and said first sealant assembly fonn an insulating glass unit an emissivity equal to or less than 0.04 suhstantially preventing the fonnation of condensation on the outer surface of the refrigeration door component without the application of electricity for heating the door component and substantially preventing fog or frost fonlzation on a surface of the componcnt. In alternate einbodiments, the method includcs providing a third sheet of glass, which may include a low-E
coating adjacent at least one of its surfaces; disposing a second sealant assembly disposed around the periphery of said second sheet of glass and said third of glass for maintaining said second sheet and said third sheet in spaced-apart relationship from each other; and wherein said insulating glass unit fiirther includes said third sheet of glass and said second sealant assembly.

[0094] The invention fiirthcr provides a substantially transparent insulating glass unit door having an outer surface and being for use with a refrigerating compartment residing in an exterior environment and having an interior refrigerating compartinent; said insulating glass unit door comprising a first sheet of glass; a second sheet of glass; a first scalant assembly disposed around the periphery of said first sheet of glass and said second sheet of glass for maintaining said first sheet and said second sheet in spaced-apart relationship from each other; a first low emissivity coating adjacent a surface of said first sheet or said second slleet of glass, and an anti-fog or anti-frost coating on a surface of one of said sheets, and said first sheet of glass, said second sheet of glass, and said first sealant assembly providing the insulating glass unit witli a U value effective to substantially prevent the formation of condensation on the ottter surface witllout the application of electricity to heat the outer surface of the insulating glass unit when the interior temperature of the refrigerating comparhnent is substantially equal to or less than zero degrees Fahrenlleit; the temperature of the exterior environment is substantially equal to or greater than seventy degrees Fahrenheit; and the humidity in the exterior enviromnent is substantially equal to or greater than sixty percent. Alternate embodiments fiu-tlier comprise a third sheet of glass; and a second sealant assembly disposed around the periphery of said second sheet of glass and said third of glass for maintaining said first sheet and said second sheet in spaced-apart relationship from each otlier, and may include a second low emissivity coating adjacent a surface of said first sheet, said second slieet or said third sheet of glass.

[0095] In alteniate enibodiments, the insulating glass unit has a U value that substantially prevents the foi7nation of condensation on the outer surface when the interior temperature of the refrigerating comparthnent is substantially equal to or less than minus forty degrees Fahrenheit; the teinperature of the exterior environment is at substantially equal to or greater than eighty degrees Fahrei-Aieit; and the humidity in the exterior enviromnent is substantially equal to or greater than sixty percent.

[0096] The invention further provides a refrigeration unit including an insulated enclosure defining a compartment, a cooling system, and a door adapted to be mounted on an opening of said compartnient, said door having an outer surface and comprising a first sheet of glass, a second sheet of glass, a first sealant assembly disposed around the periphery of said first sheet of glass and said second sheet of glass for maintaining said first sheet and said second sheet in spaced-apart relationship from each other, a first low emissivity coating adjacent the a surface of said first or said second sheet of glass, said first sheet, second sheet, first sealant asseinbly, and said first low emissivity coating fonning an insulating glass unit having a U value substantially preventing the fonriation of condensation on the outer surface of the door without the application of electricity for heating said first surface, an anti-fog coating on a surface of one of the sheets of glass; and a frame secured around the periphery of said insulating glass unit. The insulating glass tulit can have a U value substantially equal to or less than 0.2. BTU/hr-sq ft-F. In alternate einbodiments, the door fiirther comprises a third sheet of glass and a second sealant asseinbly disposed around the periphery of said second sheet of glass and said third sheet of glass for nzaintaining said second sheet and said third sheet in spaced-apart relationsliip from each other.

[0097] The invention ftuther provides a glass door for a refrigerated display case, the door comprising a first glass panel having an inside and an outside surface, a low emissivity coating on the inside surface of the first glass panel, a second glass panel having an inside and an outside surface, a low emissivity coating on the inside surface of the second glass panel, an intermediate glass panel between the first and second glass panel, a first spacer assenibly between the first and intermediate glass panels and a second spacer assemUly between the interrnediate and second glass panels wherein the first and second spacer assemblies are foi7ned from wan11 edge spacer assemUlies, and anti-fog or anti-frost coating on a surface of one of the glass panels and a fiame extending about and supporting at least one of the glass panels. In an embodinzent, the first and second glass panels have widths and heights that are identical.

[0098] The foregoing has described principles, enibodiments, and modes of operation of the present invention. However, the invention should not be construed as being limited to the particular emUodiments described above, as they should be regarded as being illustrative and not as restrictive. It should be appreciated that variations may be made in those embodiments by those slcilled in the art without departing from the scope of the present invention.

[0099] While the application of the present invention has been described in the application of a refrigerator or freezer door, other applications might include vending machines, slcyliglzts, or refrigerated trucks, automotive mirrors, particularly exten7al miiTors, saunas, steain rooms, shower doors, ticlcet booth windows, Uathroom windows, Uathroom miirors, outside coolers and freezers that are exposed to high htuliidity or rain, and any other applications in which an anti-frost or anti-fog coating/film would be desired. In some of these applications, condensation on the second or colder side of the glass may not be an issue because the glass is not in a door that is periodically opened exposing the cold glass to a more humid environment.
As a result, the key factors in designing the glass are economics (i.e., the energy costs and the cost of the glass and its installation), visible transmittance, durability, and other considerations.

[00100] While preferred embodiments of the present invention have been described above, it should be understood that such have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by the above described exeinplaiy embodiment.

[00101] Obviously, numerous modifications and variations of the present invention are possible in liglit of the above teacliings. It is tlierefore to be understood that the invention may be practiced otherwise than as specifically described herein.

Claims (108)

1. A refrigeration door having an outer surface and adapted to be mounted on a refrigerating compartment, said door comprising:
a first sheet of glass;

a second sheet of glass;

a first sealant assembly disposed around the periphery of said first sheet of glass and said second sheet of glass for maintaining said first sheet and said second sheet in spaced-apart relationship from each other;

a first low emissivity coating adjacent a surface of said first sheet or said second sheet of glass;

an anti-fog or anti-frost coating adjacent a surface of at least one of said sheets of glass; and a frame secured around the periphery of said insulating glass unit, wherein the surface having the anti-fog or anti-frost coating thereon is pretreated with a first silane, and said anti-fog or anti-frost coating comprises a second silane, which second silane is different than the first silane.

2. The refrigeration door of claim 1,wherein said first sheet and second sheets of glass, said first sealant assembly, and said first low emissivity coating forming an insulating glass unit having a U value substantially equal to or less than 0.2 BTU/hr-sq ft-F or an emissivity substantially equal to or less than 0.04.

3. The refrigeration door of claim 1, wherein the first silane comprises amino alkyl silicone.

4. The refrigeration door of claim 1, wherein the second silane comprises 3-glycidoxypropyl trimethoxysilane.

5. The refrigeration door of claim 1, wherein the anti-fog or anti-frost coating is applied as a film.

6. The refrigeration door of claim 1, wherein the anti-fog or anti-frost coating is applied as a liquid.

7. The refrigeration door of claim 1, wherein the anti-fog or anti-frost coating has a thickness of about 4 microns to about 20 microns.

8. The refrigeration door of claim 7, wherein the anti-fog or anti-frost coating has a thickness of about 10 microns to about 20 microns.

9. The refrigeration door of claim 8, wherein the anti-fog or anti-frost coating has a thickness of about 12 microns to about 15 microns.

10. The refrigeration door of claim 1, wherein the anti-fog or anti-frost coating is insoluble in water.

11. The refrigeration door of claim 1, wherein the anti-fog or anti-frost coating further comprises a mixture of:
i) a first component comprising about 46% diacetone alcohol, about 4% N-methyl Pyrrolidone, about 4% t-butanol, about 8% Cyclohexane, about 6%
2,4-pentanedione, and about 2% Aromatic 150; and ii) a second component comprising about 66% polyisocyanate, about 1% free monomeric isocyanates, about 11% xylene, about 11% n-butyl acetate, and about 11% toluene;
wherein the mixture ratio of the first component to the second component is about 100:40.

12. The refrigeration door of claim 11, wherein the anti-fog or anti-frost coating further comprises a solvent for diluting the mixture.

13. The refrigeration door of claim 12, wherein the solvent is an alcohol.

14. The refrigeration door of claim 13, wherein the alcohol is diacetone alcohol or tertiary butyl alcohol.

15. The refrigeration door of claim 1, wherein the anti-fog or anti-frost coating further comprises a mixture of:
i) a first component comprising about 46% diacetone alcohol, about 4% N-methyl Pyrrolidone, about 4% t-butanol, about 8% Cyclohexane, about 6% 2,4-pentanedione, and about 2% Aromatic 150; and ii) a second component comprising about 66% polyisocyanate, about 1% free monomeric isocyanates, about 11% xylene, about 11% n-butyl acetate, and about 11%
toluene;
wherein the mixture ratio of the first component to the second component is about 100:about 25-45.

16. The refrigeration door of claim 15, wherein the mixture ratio of the first component to the second component is about 100:about 30-33.

17. The refrigeration door of claim 16, wherein the mixture ratio of the first component to the second component is about 100:about 30.

18. The refrigeration door of claim 15, wherein the second silane is present in an amount of about 1% to about 8%.

19. The refrigeration door of claim 15, wherein the second silane is present in an amount of about 6%.

20. The refrigeration door of claim 1, further comprising:
a third sheet of glass;

a second sealant assembly disposed around the periphery of said second sheet of glass and said third sheet of glass for maintaining said second sheet and said third sheet in spaced-apart relationship from each other; and wherein said insulating glass unit further includes said third sheet of glass and said second sealant assembly.

21. The refrigeration door of claim 20, further including a second low emissivity coating adjacent a surface of said first sheet, said second sheet, or said third sheet of glass.

22. The refrigeration door of claim 2, wherein the U value of said insulating glass unit is effective to substantially prevent the formation of condensation on the outer surface of the door without the application of electricity for heating the outer surface when the interior temperature of the refrigerating compartment is substantially equal to or less than minus zero degrees Fahrenheit; the temperature of the exterior environment is substantially equal to or greater than seventy-two degrees Fahrenheit;
and the humidity in the ambient environment is substantially equal to or greater than sixty percent.

23. The refrigeration door of claim 22, further comprising:

a first chamber defined by said first sheet of glass, said second sheet of glass, and said first sealant assembly; and a gas disposed in said first chamber.

24. The refrigeration door of claim 23, wherein said first sealant assembly has a heat transfer rate substantially equal to or less than 1.73 Btu/hr-ft-F.

25. The refrigeration door of claim 23, wherein said gas is selected from the group consisting of argon, krypton, and air.

26. The refrigeration door of claim 1, wherein the interior temperature of the refrigerating compartment is substantially equal to or less than minus twenty degrees Fahrenheit; the temperature of the exterior environment is substantially equal to or greater than seventy degrees Fahrenheit; and the humidity in the exterior environment is substantially equal to or greater than sixty percent; and wherein the outer surface of the door is substantially free of condensation.

27. The refrigeration door of claim 1, wherein the interior temperature of the refrigerating compartment is substantially equal to or less than minus forty degrees Fahrenheit; the temperature of the exterior environment is substantially equal to or greater than eighty degrees Fahrenheit; and the humidity in the exterior environment is substantially equal to or greater than sixty percent; and wherein the outer surface of the door is substantially free of condensation.

28. The refrigeration door of Claim 21, wherein:

the first sheet of glass is an inner sheet of glass including a first surface and a second surface, said first surface of said inner sheet being disposed adjacent the interior of the refrigerating compartment;

the third sheet of glass is an outer sheet of glass including a first surface and a second surface, said first surface of said outer sheet being disposed adjacent the exterior environment of the refrigerating compartment;

the second sheet of glass is a middle sheet of glass disposed between said inner and outer sheets of glass;

the first sealant assembly being disposed around the periphery of said inner sheet of glass and said middle sheet of glass for maintaining said inner sheet and said middle sheet in spaced apart relationship from each other;

the second sealant assembly being disposed around the periphery of said middle sheet of glass and said outer sheet of glass for maintaining said middle sheet and said outer sheet in spaced-apart relationship from each other;

the first low emissivity coating being adjacent the second surface of said inner sheet of glass;

the second low emissivity coating being adjacent the second surface of said outer sheet of glass;

said inner sheet, outer sheet, middle sheet, first sealant assembly, second sealant assembly, and said first and second low emissivity coatings forming the insulating glass unit wherein the formation of condensation on said first surface of said outer sheet of glass is substantially prevented without the application of electricity for heating said first surface of said outer sheet of glass.

29. The refrigeration door of claim 28, wherein the anti-fog or anti-frost coating is adjacent the first surface of said inner sheet of glass.

30. The refrigeration door of claim 28, further comprising:

a first chamber defined by said inner sheet of glass, said middle sheet of glass, and said first sealant assembly;

a second chamber defined by said middle sheet of glass, said outer sheet of glass, and said second sealant assembly; and a gas disposed in said first and second chambers.

31. The refrigeration door of claim 30, wherein:

said inner, said middle, and said outer sheets of glass have a thickness substantially equal to one eighth of an inch;

said inner and said middle sheets of glass being spaced apart a distance substantially equal to one half inch; and said middle and said outer sheets of glass being spaced apart a distance substantially equal to one half inch.

32. The refrigeration door of claim 30, wherein said first sealant assembly and said second sealant assembly each have a heat transfer rate substantially equal to or less than 1.73 Btu/hr-ft-F.

33. The refrigeration door of claim 32, wherein:

said inner, said middle and said outer sheets of glass having a thickness substantially equal to one eighth of an inch:

said inner and said middle sheets of glass being spaced apart a distance substantially equal to one half inch; and said middle and said outer sheets of glass being spaced apart a distance substantially equal to one half inch.

34. The refrigeration door of claim 30, wherein said gas in said first chamber and said second chamber are the same.

35. The refrigeration door of claim 30, wherein said gas in said first chamber and said second chamber are not the same.

36. The refrigeration door of claim 30, wherein said first and second low emissivity coatings are selected from the group consisting of a titania based silver and fluorine doped tin oxide.

37. The refrigeration door of claim 30, wherein said first and second low emissivity coatings are applied with a process selected from the group consisting of sputter coating, pyrolytic coating and spray coating.

38 38. The refrigeration door of claim 30, wherein said frame is formed from a material selected from the group consisting of extruded plastic, aluminum, and fiber glass.

39. The refrigeration door of claim 28, wherein said first sealant assembly and said second sealant assembly each have a heat transfer rate substantially equal to or less than 1.73 Btu/hr-ft-F.

40. A method of manufacturing a refrigeration door component having an outer surface, said method comprising the steps of:

providing a first sheet of glass;
providing a second sheet of glass;

providing a first low emissivity coating adjacent a surface of said first sheet of glass or said second sheet of glass;

disposing a first sealant assembly around the periphery of said first sheet of glass and said second sheet of glass to maintain said first sheet and said second sheet in spaced-apart relationship from each other; and providing an anti-fog or anti-frost coating adjacent a surface of at least one of said sheets of glass, wherein the surface having the anti-fog or anti-frost coating thereon is pretreated with a first silane, and wherein said anti-fog or anti-frost coating comprises a second silane, which second silane is different than the first silane;

said first sheet of glass, said second sheet of glass, and said first sealant assembly forming an insulating glass unit wherein the formation of condensation on the outer surface of the refrigeration door component is substantially prevented without application of electricity for heating the door component.

41. The method of claim 40, wherein said first sheet of glass, said second sheet of glass, and said first sealant assembly define a first chamber; and further comprising the step of disposing a gas in said first chamber.

42. The method of claim 40, further comprising the steps of:
providing a third sheet of glass;

disposing a second sealant assembly disposed around the periphery of said second sheet of glass and said third of glass for maintaining said second sheet and said third sheet in spaced-apart relationship from each other; and wherein said insulating glass unit further includes said third sheet of glass and said second sealant assembly.

43. The method of claim 42, wherein said third sheet of glass includes a low emissivity coating adjacent a surface of said third sheet of glass.

44. The method of claim 40, wherein said first sealant assembly has a heat transfer rate substantially equal to or less than 1.73 Btu/hr-ft-F.

45. The method of claim 44, wherein:

said first and said second sheets of glass having a thickness substantially equal to one eighth of an inch; and said first and said second sheets of glass being spaced apart a distance substantially equal to one half inch.

46. The method of claim 40, further including the step of disposing said insulating glass unit in a door frame.

47. The method of claim 46, wherein said gas is selected from the group consisting of argon, krypton, and air.

48. The method of claim 40, wherein said insulating glass unit has a U value substantially equal to or less than 0.2 BTU/hr-sq ft-F or an emissivity substantially equal to or less than 0.04.

49. The method of claim 40, wlierein said low emissivity coating is selected from the group consisting of a titania based silver and fluorine doped tin oxide.

50. The method of claim 40, wherein said low emissivity coating is applied with a process selected from the group consisting of sputter coating, pyrolytic coating and spray coating.

51. The method of claim 42, wherein said first and second sealant assemblies have a heat transfer rate substantially equal to or less than 1.73 Btu/hr-ft-F.

52. The method of claim 44, further including the step of disposing said insulating glass unit in a door frame.

53. The method of claim 40, wherein said first sealant assembly is a composite extrusion comprising a combination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim, and a vapor barrier.

54. The method of claim 40, wherein said first sealant assembly is a Comfort Seal sealant assembly.

55. The method of claim 42, wherein said second sealant assembly is a composite extension comprising a combination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim, and a vapor barrier.

56. The method of claim 42, wherein said second sealant assembly is a Comfort Seal sealant assembly.

57. The method of claim 40, wherein at least one of said first sealant assembly and said second sealant assembly comprises a warm edge seal.

58. A substantially transparent insulating glass unit door having an outer surface and being for use with a refrigerating compartment residing in an exterior environment and having an interior refrigerating compartment; said insulating glass unit door comprising:

a first sheet of glass;

a second sheet of glass;

a first sealant assembly disposed around the periphery of said first sheet of glass and said second sheet of glass for maintaining said first sheet and said second sheet in spaced-apart relationship from each other;

a first low emissivity coating adjacent a surface of said first sheet or said second sheet of glass;

an anti-fog or anti-frost coating adjacent a surface of at least one of said sheets of glass, wherein the surface having the anti-fog or anti-frost coating thereon is pretreated with a first silane, and wherein said anti-fog or anti-frost coating comprises a second silane, which second silane is different than the first silane; and said first sheet of glass, said second sheet of glass, and said first sealant assembly providing the insulating glass unit with a U value effective to substantially prevent the formation of condensation on the outer surface without the application of electricity to heat the outer surface of the insulating glass unit when the interior temperature of the refrigerating compartment is substantially equal to or less than zero degrees Fahrenheit; the temperature of the exterior environment is substantially equal to or greater than seventy degrees Fahrenheit; and the humidity in the exterior environment is substantially equal to or greater than sixty percent.

59. The door of claim 58, further comprising:

a third sheet of glass; and a second sealant assembly disposed around the periphery of said second sheet of glass and said third of glass for maintaining said first sheet and said second sheet in spaced-apart relationship from each other.

60. The door of claim 59, further including a second low emissivity coating adjacent a surface of said first sheet, said second sheet or said third sheet of glass.

61. The door of claim 60 wherein the insulating glass unit has a U value that substantially prevents the formation of condensation on the outer surface when the interior temperature of the refrigerating compartment is substantially equal to or less than minus forty degrees Fahrenheit; the temperature of the exterior environment is substantially equal to or greater than eighty degrees Fahrenheit; and the humidity in the exterior environment is substantially equal to or greater than sixty percent.

62. The door of claim 60, wherein said low emissivity coating is effective to cause the insulating glass unit to have a U value substantially equal to or less than 0.2 BTU/hr-sq ft-F.

63. The door of claim 59, wherein said first sealant assembly and said second sealant assembly each have a heat transfer rate substantially equal to or less than 1.73 Btu/hr-ft-F.

64. The door of claim 58, wherein the insulating glass unit has an emissivity substantially equal to or less than 0.04.

65. The door of claim 58, wherein the interior temperature of the refrigerating compartment is substantially equal to or less than minus twenty degrees Fahrenheit;
the temperature of the exterior environment is substantially equal to or greater than seventy degrees Fahrenheit; and the humidity in the exterior environment is substantially equal to or greater than sixty percent.

66. The door of claim 58, wherein the interior temperature of the refrigerating compartment is substantially equal to or less than minus forty degrees Fahrenheit; the temperature of the exterior environment is substantially equal to or greater than eighty degrees Fahrenheit; and the humidity in the exterior environment is substantially equal to or greater than sixty percent.

67. A refrigeration unit including an insulated enclosure defining a compartment, a cooling system, and a door adapted to be mounted on an opening of said compartment, said door having an outer surface and comprising:

a first sheet of glass;

a second sheet of glass;

a first sealant assembly disposed around the periphery of said first sheet of glass and said second sheet of glass for maintaining said first sheet and said second sheet in spaced-apart relationship from each other;

a first low emissivity coating adjacent the a surface of said first or said second sheet of glass;

said first sheet, second sheet, first sealant assembly, and said first low emissivity coating forming an insulating glass unit wherein the formation of condensation on the outer surface of the door is substantially prevented without the application of electricity for heating said first surface;

an anti-fog or anti-frost coating adjacent a surface of at least one of said sheets of glass, wherein the surface having the anti-fog or anti-frost coating thereon is pretreated with a first silane, and wherein said anti-fog or anti-frost coating comprises a second silane, which second silane is different than the first silane; and a frame secured around the periphery of said insulating glass unit.

68. The refrigeration unit of claim 67, further comprising:

a third sheet of glass; and a second sealant assembly disposed around the periphery of said second sheet of glass and said third of glass for maintaining said second sheet and said third sheet in spaced-apart relationship from each other.

69. The refrigeration unit of claim 67, further comprising:

a first chamber defined by said first sheet of glass, said second sheet of glass, and said first sealant assembly;

a second chamber defined by said middle sheet of glass, said outer sheet of glass, and said second sealant assembly; and a gas disposed in said first and second chambers.

70. The refrigeration unit of claim 68, wherein said first sealant assembly and said second sealant assembly each have a heat transfer rate substantially equal to or less than 1.73 Btu/hr-ft-F.

71. The refrigeration unit of claim 67, wherein the door has an emissivity substantially equal to or less than 0.04.

72. The refrigeration unit of claim 67, wherein the insulating glass unit has a U
value substantially equal to or less than 0.2. BTU/hr-sq ft-F.

73. The refrigeration unit of claim 67, wherein said first sealant assembly has a heat transfer rate substantially equal to or less than 1.73 Btu/hr-ft-F.

74. The refrigeration door of claim 1, wherein said first sealant assembly is a composite extrusion comprising a combination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim, and a vapor barrier.

75. The refrigeration door of claim 1, wherein said first sealant assembly is a Comfort Seal sealant assembly.

76. The refrigeration door of claim 20, wherein said second sealant assembly is a composite extrusion comprising a combination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim, and a vapor barrier.

77. The refrigeration door of claim 20, wherein said second sealant assembly is a Comfort Seal sealant assembly.

78. The door of claim 58, wherein said first sealant assembly is a composite extrusion comprising a combination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim, and a vapor barrier.

79. The door of claim 58, wherein said first sealant assembly is a Comfort Seal sealant assembly.

80. The door of claim 59, wherein said second sealant assembly is a composite extrusion comprising a combination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim, and a vapor barrier.

81. The door of claim 59, wherein said second sealant assembly is a Comfort Seal sealant assembly.

82. The door of claim 59, wherein at least one of said first sealant assembly and said second sealant assembly comprises a warm edge seal.

83. The refrigeration unit of claim 67, wherein said first sealant assembly is a composite extrusion comprising a combination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim, and a vapor barrier.

84. The refrigeration unit of claim 67, wherein said first sealant assembly is a Comfort Seal sealant assembly.

85. The refrigeration unit of claim 68, wherein said second sealant assembly is a composite extrusion comprising a combination of polyisobutylene sealant, hot melt butyl sealant, desiccant matrix, rubber shim, and a vapor barrier.

86. The refrigeration unit of claim 68, wherein said second sealant assembly is a Comfort Seal sealant assembly.

87. The refrigeration unit of claim 68, wherein at least one of said first sealant assembly and said second sealant assembly comprises a warm edge seal.

88. An anti-fog or anti-frost coating coinprising a mixture of:

i) ~a first component comprising about 46% diacetone alcohol, about 4% N-methyl Pyrrolidone, about 4% t-butanol, about 8% Cyclohexane, about 6%
2,4-pentanedione, and about 2% Aromatic 150; and ii) ~a second component comprising about 66% polyisocyanate, about 1% free monomeric isocyanates, about 11 % xylene, about 11 % n-butyl acetate, and about 11% toluene;
wherein the mixture ratio of the first component to the second component is about 100:about 30-33.

89. The anti-fog or anti-frost coating of claim 88, wherein the mixture ratio of the first component to the second component is about 100:about 30.

90. The anti-fog or anti-frost coating of claim 88, wherein the mixture further comprises a silane.

91. The anti-fog or anti-frost coating of claim 90, wherein the silane comprises 3-glycidoxypropyl trimethoxysilane.

92. The anti-fog or anti-frost coating of claim 91, wherein the silane is present in an amount of about 1% to about 8%.

93. The anti-fog or anti-frost coating of claim 92, wherein the silage is present in an amount of about 6%.

94. The anti-fog or anti-frost coating of claim 88, wherein the anti-fog or anti-frost coating has a thickness of about 4 microns to about 20 microns.

95. The anti-fog or anti-frost coating of claim 94, wherein the anti-fog or anti-frost coating has a thickness of about 10 microns to about 20 microns.

96. The anti-fog or anti-frost coating of claim 95, wherein the anti-fog or anti-frost coating has a thickness of about 12 microns to about 15 microns.

97. A method of forming an anti-fog or anti-frost coating on at least a portion of a substrate, the method comprising:
pretreating at least a portion of the substrate with a first silane;
preparing a mixture of:
i) ~a first component comprising about 46% diacetone alcohol, about 4% N-methyl Pyrrolidone, about 4% t-butanol, about 8% Cyclohexane, about 6%
2,4-pentanedione, and about 2% Aromatic 150; and ii) ~a second component comprising about 66% polyisocyanate, about 1% free monomeric isocyanates, about 11% xylene, about 11% n-butyl acetate, and about 11% toluene;
wherein the mixture ratio of the first component to the second component is about 100:about 30-33;

applying the mixture to the substrate; and curing the substrate.

98. The method of claim 97, wherein the mixture does not contain additional solvents.

99. The method of claim 97, wherein the mixture ratio of the first component to the second component is about 100:about 30.

100. The method of claim 97, wherein the mixture is applied with a single coating step.

101. The method of claim 97, wherein the curing is achieved in a single curing cycle.

102. The method of claim 97, further comprising adding a second silane to the mixture, wherein the second silane is different than the first silane.

103. The method of claim 102, wherein the second silane comprises 3-glycidoxypropyl trimethoxysilane.

104. The method of claim 103, wherein the second silane is present in an amount of about 1% to about 8%.

105. The method of claim 104, wherein the second silane is present in an amount of about 6%.

106. The method of claim 97, wherein the first silane comprises amino alkyl silicone.

107. The method of claim 97, wherein the pretreating comprises preparing a rinse water mixture comprising about 1% or less of the first silane and applying said mixture to said portion of the substrate.

108. The method of claim 107, wherein the rinse water mixture comprises about 0.031% of the first silane.