Abstract:
An insulated glass unit (IGU) comprises impact resistant safety films on the inner surfaces of the glass panes, providing an impact resistant, energy-saving IGU for use in windows and doors. A layer of the safety film providing energy savings may be trimmed from the edges of a glass pane; witch may be sealed within the interior of the IGU, preventing corrosion while providing no loss in impact resistance. A scratch-resistant, chemical vapor deposited coating may be added to an interior glass surface (i.e. facing the building interior) in order to prevent heat loss from the building. An IGU may have an Energy Star rating for both summer and winter use.

Description:
RELATED APPLICATION 
       [0001]    This present application is a continuation of application Ser. No. 10/975,512, filed Oct. 28, 2004, now Allowed and application Ser. No. 10/793,958, filed Mar. 5, 2004, now Allowed. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The field relates to insulated glass units (IGUs) having a plurality of glass panes for use in energy efficient windows. 
       BACKGROUND 
       [0003]    Insulated glass windows or door units have been known for many years to reduce the heat transfer between the interior house and the environment. To further improve the insulating properties, the art taught making solar control coated and low emissivity (low-E) coated glass or film. Solar control is a term describing the property of regulating the amount of solar heat energy, which is allowed to pass through a glass article into an enclosed space such as a building or an automobile interior. Low emissivity is a term describing the property of an article&#39;s surface wherein the absorption and emission of mid-range infrared radiation suppressed, making the surface a mid-range infrared reflector and thereby reducing heat flux through the article by attenuating the radiant component of heat transfer to and from the low emissivity surface. By suppressing solar heat gain, building and automobile interiors are kept cooler, allowing a reduction in air conditioning requirements and costs. Efficient low emissivity coatings may improve comfort during both summer and winter by increasing the thermal insulating performance of a window, but available glass systems usually have better energy efficiency in retaining heat or blocking sunlight and seldom both due well. 
         [0004]    Two typical coating methods to make solar control and low-E coatings are “in-line” and “off-line” coatings. The in-line method uses a chemical deposition method involving doping with different chemicals to make an infrared absorbing layer and low-E layer as described in U.S. Pat. Nos. 5,750,265, 5,897,957 and 6,218,018. The off-line method uses sputtering deposition to make both coatings. 
         [0005]    Impact resistant glass is described in detail in the Florida Building Code. Basically, it specifies a testing protocol for a window glass to withstand up to nine pounds of force from a 2×4 board shot at the glass up to 50 feet/second. Withstanding both shots with one in the center and one in the corner without penetration is considered as a pass. 
         [0006]    U.S. Pat. Nos. 4,799,745 and 5,071,206 describe a multilayered polyethyleneterephthalate (PET) window film construction, which gives both solar control and low-E properties. The coating contains silver metal layers and indium-tin oxide layers in an alternate construction. The film has a high visible light transmission, above 70%, and a low visible light reflection, about 8%. The total solar heat rejection is about 56%. The color of the coating is light green. It has a very good solar control and low-E performances. However, corrosion is a major concern. To make an IGU, the window pane needs edge deletion and filling with inert gas in the IGU to prevent the coating from corroding. The multi-layered coating has to be exposed within the IGU to achieve both low-E and solar control functions. As a result, the manufacturing process for an IGU is expensive and difficult. 
         [0007]    U.S. Pat. Nos. 5,332,888 and 6,558,800 disclose a multilayered sputtering window glass construction (off-line method) which also achieves both solar control and low-E properties. The description contains a silver metal layer sandwiched by zinc oxide layers or a silver metal layer sandwiched by nickel chrome and silica nitrite layers. Similar to sputtered PET film, they also face corrosion, chemical resistant and scratch resistant concerns, which make manufacturing difficult and expensive. 
         [0008]    U.S. Pat. No. 6,546,692 assigned to Film Technologies International, Inc., discloses a method of laminating a safety film on the inside surfaces in an IGU to build an impact resistant window. The safety feature is very important for IGU&#39;s to withstand hurricane, earthquake, and terrorism. However, the low-E property is destroyed or significantly reduced once a safety film is laminated over any low-E coating surface. 
         [0009]    Besides solar control, low-E, and impact resistance, other desirable properties include an economic and repeatable manufacturing process, durability, maintenance, light transmission, visibility, color, clarity and reflection. 
         [0010]    To meet the Government (Department of Energy) Energy Star Qualification Criteria for Windows, Doors and Skylights and Florida Building Code for impact resistant windows, a new IGU is required for the window/door industry. 
         [0011]    It is known that energy is controlled at a window by the reflection, transmission and absorption of solar radiation by the glazing type and emissivity of the glazing. An Insulated Glass Unit (IGU), which has a plurality of glass panes spaced apart and joined in a unit, contributes to the heat gain or loss of the window by three mechanisms: conduction of heat, convection whereby air currents within the IGU act as the transfer agent for heat, and radiation or reradiation of the heat absorbed. When solar radiation strikes an IGU energy is absorbed and either conducted or reradiated, The ability to reradiate is characterized by a surfaces emissivity 
         [0012]    When a spectrally selective, vacuum deposited, metal or metallic coating is incorporated into the surface within an IGU, it assists with energy release by absorbing the IR portion of the solar spectrum and reradiating the absorbed energy to the surrounding atmosphere in the direction of the surface of the coating and the atmosphere interface. If the spectrally selective coating is encapsulated within a film system and the coating itself is not exposed to the environment, it has been discovered that the majority of the ability to reradiate energy is lost as conduction becomes the major pathway for the absorbed energy. Thus, it is important for a spectrally selective coating to be exposed to an atmosphere or void if surface emissivity is used for reradiation of the absorbed energy. Standard laminated glass where two pieces of glass are adhered together by a plastic and have no void or atmosphere separating the glass panes do not incorporate spectrally selective, vacuum deposited, metal or metallic coatings, because these coatings would not be effective in emitting absorbed energy back to the outside of the laminated window unit. 
         [0013]    Also it is known that the reactivity of spectrally selective coatings consisting of multi-layers of vacuum deposited or sputter-deposited metals or metallic compounds can corrode depending on the chemical composition when exposed to moisture, light. or other chemicals. When this happens the corrosion products are aesthetically displeasing and the solar radiation controlling performance of the coatings is lost. 
       SUMMARY OF THE INVENTION 
       [0014]    The ability to incorporate a spectrally selective, vacuum deposited, metal or metallic coating 
         [0015]    within an IGU utilizing a film composite having an emitting coating on the inner surface or surfaces of the IGU provides enhanced absorbed heat dissipation capability as it takes advantage of the filtering out of IR light, absorbs most of the UV portion of the spectrum, allows for neutral colored visible light to be transmitted, and takes advantage of the emissivity of the coating to reradiate absorbed light. This provides for a better insulation value for the IGU portion of the window and enhanced safety performance because of the film laminate adhered to the inner surface of the glass. 
         [0016]    Spectrally selective coatings are protected immediately after manufacturing a multi-layered film composite by providing temporary protective film which can be removed without harming the spectrally selective metallic film. This allows handling, shipping and processing without damaging the spectrally selective coating prior to completion of an IGU incorporating the film. The protective film is removed just before IGU manufacture which then incorporates these spectrally selective coatings within the cavity of an IGU. The cavity exposes the films, to a benign environment, substantially free of moisture. These measures ensure the integrity of the spectrally selective coating and the long term performance of the IGU as a superior insulator. Spectrally selective, vacuum deposited or sputter-deposited, metal or metallic coatings on a surface of a multi-ply plastic film composite in an IGU provides both impact resistance and energy efficiency without corroding the metallic coating. 
         [0017]    For example, a glass substrates adapted for insertion into frame unit of an IGU by laminating film composite comprising a metallized coating on an outer layer of a thin, multi-film base to the glass pane, A protective film is temporarily applied over the metallized layer until the film is adhesively bonded to the glass pane, which is then sealed within the interior space of the IGU. The protective film is removed and an outer edge strip of the outer layer of the multi-film layer may be stripped away. The glass pane surfaces may be mounted in a frame with a metallized layer facing inwardly toward the opposite glass pane. A spacer keeps the glass panes apart and sealant is placed in the cavity formed by the space between the glass panes and the spacer to form a sealed IGU. 
         [0018]    An advantage of the IGU is improved impact resistance combined with an energy efficiency that earns the Department of Energy Star Qualification criteria. Such an IGU may meet or exceed requirements of Florida and Miami Dade County for large missile impact, also. The process provides for a comparatively low cost and corrosion/discoloration free low energy window coating on an IGU. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0019]    The invention is best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings: 
           [0020]      FIG. 1  is an exploded cross sectional view of a film composite of this invention containing a metallized layer. 
           [0021]      FIG. 2  is an exploded cross sectional view of the film composite of  FIG. 1  with a protective film over the metallized layer. 
           [0022]      FIG. 3  is a cross sectional view of the film composite of  FIG. 2  about to be bonded to a glass pane. 
           [0023]      FIG. 4  is a cross sectional view of the outer film metallized layer edge stripped away. 
           [0024]      FIG. 5  is a cross sectional view of two glass panes adapted for mounting in a frame with a spacer in between two film composite metallized layers. 
           [0025]      FIG. 6  is a cross sectional view of two glass panes adapted for mounting in a frame with a spacer in between a film composite metallized layer and a non-metallized layer. 
           [0026]      FIG. 7  is a cross sectional view of the two glass panes of  FIG. 5  mounted in a frame. 
           [0027]      FIG. 8  is a side elevational view of an insulated glass window of this invention mounted in a window frame. 
           [0028]      FIG. 9  is a transmission spectrum of a glass pane on which is applied a solar control layer and a low-E layer on one surface. 
           [0029]      FIG. 10  is a transmission spectrum of a glass pane on which is applied an alternate antimony based solar control and low-E coating. 
           [0030]      FIG. 11  is a transmission spectrum of a glass pane on which is applied a low-E coating. 
       
    
    
     DETAILED DESCRIPTION  
       [0031]    In the example of  FIGS. 1 and 2 , a film composite  10  is formed by laminating several layers of polyethyleneterephthalate (PET) films together. PET film layers  12  and  14  are held together by acrylic pressure sensitive adhesive  16  and PET film layer  18  is bonded to PET film layer  14  by acrylic pressure sensitive adhesive  20 . PET layer  18  incorporates a spectrally selective vacuum deposited metallic coating  22  and protective coating is applied to the outer side of PET layer  18  to protect coating  22 . In alternative examples, the method applies the metallized coating to the outer layer film  18  either before or after the outer layer of film  18  is adhesively bonded with an adjacent layer of multi-layered film composite film. 
         [0032]    The individual plies of PET  14  and  16  do not have to be of the same thickness and are held together with the acrylic pressure sensitive adhesive  20 . The different layers of PET film  12  and  14  can equal or vary significantly in thickness depending on desired properties, i.e., 2 mils laminated with mils, or 4 mils laminated to 4 mils, or 1 mil laminated to mils, etc. It is typical for the spectrally controlling PET film  18  to be based on a 1 to 3 mil PET film, but can be thicker. The resulting film composite  10  is classified as a safety film and is used to coat a window pane  26  as shown in  FIGS. 3 and 4  by attachment with acrylic adhesive  28 . This composite film thickness can vary from 4 mils to 30 mils total depending on the end use desired and the choice of individual PET film thickness. Other safety film can be used and the individual ply thickness can vary as can the number of plies used to manufacture the film composite. These films can be made of polycarbonate polyester or other like polymeric materials. It is important that during the manufacturing of the composite  10  that a protective, temporary, masking film is applied to protect the spectrally selective film  18  from the environment and contamination. The laminated film composite is laminated to one surface of the glass pane  26  with adhesive  28 . 
         [0033]    Just prior to manufacturing the IGU, the protective coating  24  is removed from the glass/laminated film composite surfaces as seen in  FIG. 4 . With care, and using the edge of the glass  26 , a cut  32  through the outermost layer  18  of the film composite  10  parallel with the edge  30  of the glass  26  made on all sides of the glass/film composite laminate. Care is taken to only cut through the outer film  18  and to not disturb the other plies of PET film. The cut  32  is typically from 3/16″ to “from the edge  30  of the glass  26 . The thin strip, bordered by the edge  30  of the glass, formed from the cut  32  is then removed leaving a picture frame appearance,  FIG. 4 , to the glass pane. 
         [0034]    A glass pane/laminated film composite  10   a  shown in  FIG. 6  can be similarly made using only PET films and not incorporating a spectrally controlled film. This too is classified as a safety film and is described in U.S. Pat. No. 6,546,692, incorporated herein by reference. 
         [0035]    If desired, for aesthetics or performance, layers of colored film can be used with the film composites  10  and  10   a.  The color will influence the overall transmitted light but will not adversely influence the emissivity of the exposed spectrally selective coating. 
         [0036]    Two of the laminated window panes shown in  FIG. 5  are faced to each other with the spectrally selective coatings facing inward and a spacer  34  shown in  FIGS. 5 and 6  having a top inboard surface  36  and a bottom outboard surface  38  is placed between the laminated surfaces of the two panes  26  and  40  and pressed together to form a multiple window pane composite or IGU shown in  FIGS. 5 and 6 . A structural silicone or butyl or like IGU glazing sealant  42  is backfilled from the outboard surface  38  of the spacer  34  to the edge  30  of the laminated window pane window as seated in a frame  44  as seen in  FIG. 7 . The IGU is preferably positioned on a setting block when installed in frame  44 . The panes also can be used in a door system. 
         [0037]    As an al ternate IGU composition, one can laminate to one of the panes  40  in the above IGU a glass/film composite  10   a  whereby there is no spectrally controlling layer in the film composite When this glass/film composite  10   a  is substituted in the pane  40  utilizing a spectrally controlling film layer  22  is not a needed. Then there is no need to remove a portion of the film composite as there is no spectrally selective coating to corrode. The film composite  10  or  10   a  can cover the total pane. The resulting IGU made with using one pane  26  with a spectrally controlling layer and one pane  40  without a spectrally controlling layer is shown in  FIG. 6 . 
         [0038]    The spacer  34  employed should have a thickness sufficient so its outboard surface  38  extends about ¼″ to ⅝″ from the window pane edge  30  and its inboard surface is on the site line” of the window frame of the window in which it is placed. The width of the spacer  34  between the laminated window panes should be about ¼″ to 9/16″ but may be smaller or larger in order to allow for an overall thickness appropriate for the window in which it is being glazed. 
         [0039]    Typically, a desiccant agent is incorporated with the spacer system in order to initially scavenge residual moisture within the IGU cavity and throughout the service life of the IGU. 
         [0040]    Inert gas or mixtures may be used to replace the air within the IGU cavity and these techniques are well known within the industry. The inert gas or mixtures aid with the insulating performance of the IGU by mitigating the convection pathway for heat transfer, especially when incorporating a spectrally selective coating on the inside of the IGU cavity to emit absorbed energy. 
         [0041]    The dimension by which the framing system overlaps the edge of the glazing infill or IGU should be between ˜ to 1 inch with ⅝″ to ⅞″ being preferred. 
         [0042]    The minimum glass pane  26  or  40  thickness will vary depending on the area of use, wind load chart and building codes. About ⅜″ glass is suitable in most areas with a laminated film inner surface thickness of 0.0008 to 0.02 inch. 
         [0043]    To meet solar control criteria, it would be ideal to coat a solar reflective coating on the exterior surface of a window pane. However, because of environmental aging, chemical reaction, corrosion or scratching caused by cleaning the window, the coating cannot be placed on the exterior surface. 
         [0044]    Referring to  FIG. 8 , a solar control coating  112  is coated on the inside surface  102  of the first glass pane  114 . The coating can be made either by sputtering deposition or chemical deposition method. A sputtered coating, as used in  FIG. 9 , has silver or other IR reflective metal layers sandwiched by metal oxide layers. This coating reflects more infrared rays than it absorbs. The metal composite provides the window glass with high visible light transmission and low visible light reflection as well as low-E properties. As a result, it is an ideal heat mirror product. The chemical vapor deposition coating has better chemical and scratch resistance than the sputtering coated product. It will absorb solar energy instead of reflect it. As a result, it builds a heat stress over the glass pane and could cause glass breakage. Another disadvantage is that it has a lower visible light transmission than sputtering coated glass to achieve the similar solar performance. The transmission spectra for the preferred solar control coatings are shown in  FIG. 9  and  FIG. 10 . The most preferred solar control coating sold by Pittsburg Plate Glass Co. is shown in  FIG. 9 . A safety film  116  is laminated over the sputtered coating  112  on surface  102  to reinforce the glass and also protect the metal from corrosion and other chemical reactions during aging. However, once laminated with a safety film, it destroys or significantly reduces the low-E property. 
         [0045]    A safety film  116  is constructed with three layers of clear PET film laminated to each other with a pressure sensitive adhesive. The safety film has a thickness of 0.004 to 0.025 inches. The preferred thickness is 0.008 to 0.018 inches and most preferred is a film thickness of 0.015 inches. The adhesive is an acrylic based pressure sensitive type. The coat weight of the mounting adhesive, which bonds the safety film to the glass, is between 12-17 Ib/ream. The multi-layered construction is better than a single layer PET film because it improves the film&#39;s impact resistance. More layers are better for impact resistance but the multi-layered laminating construction can cause distortion problem. 
         [0046]    To meet the low-E requirement, a low-E coated glass film  118  has to be used. The function of the low-E coating  118  is to reflect the mid-range infrared rays and reduce the heat flux through the window glass. The coating faces the inside of the room on glass surface  4  as shown in  FIG. 8 . The preferred low-E coating is chemical deposited over the glass. The E value 03-0.25. The preferred E value is 0.08-0.20. The most preferred E value is 0.17 or lower. The visible light transmission (VLT) of the low-E glass is 35-90%. The preferred VLT is 60-85%. The most preferred VLT is 80%. The preferred color is neutral or light green. A safety film  120  is laminated on the interior surface  103  of glass  122  to reinforce the interior glass. 
         [0047]    The coated window glass  114  or  122  can be any type, such annealed, heat strengthened or tempered. 
       EXAMPLE 1 
       [0048]    The exterior glass pane  114  uses PPG&#39;s SB60 CL-3 sputtered solar control low-E glass. The dimension is 2.5″×0.5″×⅛″ The glass has a visible light transmission (VLT) of 75.9%. The VLT is measured with a Densitometer made by Gretag Macbeth Company. The emissivity reading (E value) is 0.05. The data is obtained through an Emissometer manufactured by Devices &amp; Service Company. The color is light yellow green with a reading of a*=−2.19, b*=2.04, and L=90.79. Where a* is CIELAB color space coordinate defining the red/green axis; b* is CIELAB color space coordinate defining the yellow/blue axis; and L is CIELAB color space coordinate defining the lightness axis. The color numbers are measured with a Spectrogard made by BYK Gardner Company. The transmission spectrum of the coated glass is measured by Lambda 900 UV/VIS/NIR spectrometer manufactured by Perkin Elmer Company. The spectrum is shown in  FIG. 9 . 
         [0049]    The interior glass pane  122  uses Pilkington North America, Inc., Energy Advantage Low-E glass. It is coated on surface through a chemical vapor deposition method. The dimension is the same as the exterior glass pane. The glass has a VLT reading of 79%. The emissivity reading is 0.18. The color light neutral and yellow, a*=−, b*=1, and L=92.50. The transmission spectrum of the low-E glass is shown in  FIG. 11 . 
         [0050]    A 15 mil safety film is constructed with three layers of mil clear PET film laminated to each other with an acrylic pressure sensitive adhesive. The coat weight for the laminating adhesive is 11 Ib/ream. A mounting adhesive is used to bond the 15 mil safety film and glass together. The mounting adhesive chooses the same adhesive as the laminating adhesive but has higher coat weight. It is about 16 Ib/ream. A UV absorber added into the adhesive formulation to eliminate UV spectrum from the sun. 
         [0051]    An insulating glass unit  110  (IGU) as shown in  FIG. 8  is constructed in the way described as follows. A safety film  116  is laminated to the solar control coated surface  112  of the exterior glass  114  through a laminator. A clean room environment is required. A second safety film  120  is laminated to the noncoated surface of the interior glass  122 . A spacer  114  is positioned to the four edges of the first glass pane  114  over the safety film  116 . The second glass pane  122  is over lapped to the first pane with safety film  120  facing the safety film  116  on the inside surface of the first glass  114 . The four edges are sealed with an appropriate sealant such as buy tal or silicone sealants. The IGU is filled with argon gas  126  to improve insulation. The final construction as shown in  FIG. 8  is that solar control coating  112  is on the inside surface  102  of the exterior glass  114  and the low-E coating  118  is on the exterior surface  104  of glass  122  facing the inside of a room. The safety films  116  and  120  are on the inside surfaces  102  and respectively, of glass  114  and  122 . 
         [0052]    Both the exterior solar control glass pane  112  and interior low-E glass pane  122  are laminated with a 15 mil safety film on surfaces  102  and  103  respectively, and tested with a Perkin Elmer Lambda 900 uv/vis/nir spectrometer. The emissivity number measured with a digital voltmeter. The data are input into a Window 5.0 program for analyzing window thermal performance. The software is developed by Lawrence Berkeley National Laboratory. The results are listed in Table 1. The U-value is the amount of conductive heat energy transferred through one square foot of a specific glazing system for each temperature difference between the indoor and outdoor air. The lower the U-value, the better insulating qualities of the glazing system. Solar Heat Gain Coefficient (SHGC) is measurement of the percentage of solar energy that is either directly transmitted or absorbed and then re-radiated into a building. The lower the coefficient, the better the window able to reduce solar heat. 
         [0053]    A scratch resistance test is conducted with Taber 5130 Abraser. The test follows the ASTM D 1003 method. After 100 cycle abrasion, the delta haze for the low-E coating on the Pilkington North America, Inc., Energy Advantage low-E glass 34%. The haze is measured with BYK Gardner s Haze Gard Plus meter. 
       EXAMPLE 2 
       [0054]    Exterior glass pane  114  uses Pilkington North America, Inc., Solar E glass. The dimension is 2.5″×5″×⅛″. The glass has a visible light transmission of 60.3%. The emissivity reading is 0.20. The color is blue, a*=−218, b*=−258, L=82.40. The glass has a transmission spectrum shown in  FIG. 10 . 
         [0055]    The interior glass  122  uses Pilkington North America, Inc., Energy Advantage Low-E glass. Following the same process as set forth for Example 1, an IGU is made and tested. The U-value and SHGC reading are listed in table 1. 
       EXAMPLE 3 
       [0056]    Exterior glass pane  114  uses PPG&#39;s SB60 CL-3 sputtered solar control low-E glass. The interior glass  122  uses Pilkington s Solar E glass. Following the same process as set forth for Example 1, an IGU is made and tested. The U-value and SHGC reading are listed in Table 1. 
         [0057]    A scratch resistance test is conducted in the same manner as described in Example 1. After 100 cycles of abrasion testing, the solar control low-E coating is removed. The glass is clear and has less haze. The delta haze is −0.60%. 
       EXAMPLE 4 
       [0058]    Both exterior  114  and interior  122  glass panes are clear glass. The dimension is the same as described in Example 1. 
         [0059]    A 17 mil safety and solar control low-E film constructed in a way that a 2 mil sputtering coated solar control low-E film is laminated onto the 15 mil safety film with metal surface exposed. The laminating adhesive is the same acrylic pressure sensitive adhesive as previously described. 
         [0060]    An IGU is constructed in the same way as described in Example 1. The only difference is that the 17 mil safety and solar control low-E film is laminated on the inside surface of glass  114 , and the 15 mil safety film is laminated on the inside of glass  122 . Both exterior  114  and interior  122  glass panes are clear glass. The U-value and SHGC are described in Table 1. 
       EXAMPLE 5 
       [0061]    Both exterior  114  and interior  122  glass panes use PPG SB60CL-3 solar control low-E glass. An impact resistance unit is built the same way as described in Example 1. The only difference is that the interior glass  122  has the sputtering coated solar control and low-E coating. The U-value and SHGC are measured in Table 1. The energy performance is very good but corrosion has been found in the lab sample on a surface. 
       EXAMPLE 6 
       [0062]    Exterior glass  114  uses PPG&#39;s SB60CL-3 and interior glass uses a clear glass. A safety film is laminated on the inside surfaces of glass  114  and  122 . The U-value and SHGC are measured and listed in Table 1. The data shows that the glass E value is significantly weakened. 
       EXAMPLE 7 
     Weathering Test 
       [0063]    A safety film is laminated over PPG&#39;s SB60CL-3 coating. The glass pane is tested in a QUV chamber for accelerated weathering. The glass side faces the UV lamp. The testing follows ASTM G154 methods. After 5,500 hours of exposure no corrosion or chemical reaction between the adhesive and sputtered metal is found. The glass VLT and E-value has not changed. However, the corrosion was found in the uncovered area of the low-E glass. The mounting adhesive is found slightly yellow after UV exposure. 
       Corrosion Test 
       [0064]    Both Energy Advantage Low-E and Solar E glass panes are placed in a bucket filled with a little water. The bucket placed in a 135 F hot room for 14 days. No corrosion is found. Both the glasses have very good corrosion and chemical resistance. They are made through a chemical vapor deposition process. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 IGU energy performance data in the center of the glass: 
               
             
          
           
               
                   
                   
                 Total VLT 
                   
                   
               
               
                 No. 
                 IG Unit Construction 
                 % 
                 U-Value 
                 SHGC 
               
               
                   
               
             
          
           
               
                 Government 
                 Energy Star Criteria 
                   
                 ≦0.35 
                 ≦0.40 
               
               
                 requirements 
               
               
                 Example 1 
                 Glass/sb60cl-3SG15 
                 50.1 
                 0.34 
                 0.32 
               
               
                   
                 Mil/Ar/SG15 
               
               
                   
                 Mil/glass/EA-low E 
               
               
                 Example 2 
                 Glass/solar E/SG15 
                 41.7 
                 0.34 
                 0.40 
               
               
                   
                 Mil/Ar/SG15 
               
               
                   
                 Mil/glass/EA-low E 
               
               
                 Example 3 
                 Glass/sb60cl-3/SG15 
                 37.2 
                 0.35 
                 0.28 
               
               
                   
                 Mil/Ar/SG15 
               
               
                   
                 Mil/glass/solar E 
               
               
                 Example 4 
                 Glass/17 mil solar 
                 58.9 
                 0.26 
                 0.35 
               
               
                   
                 E/Ar/SG 15 mil/glass 
               
               
                 Example 5 
                 SB60cl-3 glass/SG15 
                 56.5 
                 0.31 
                 0.30 
               
               
                   
                 Mil/Ar/SG15 
               
               
                   
                 Mil/sb60cl-3 
               
               
                   
                 Glass 
               
               
                 Example 6 
                 SB60cl-3 glass/SG15 
                 62.9 
                 0.46 
                 0.35 
               
               
                   
                 Mil/Ar/SG15 
               
               
                   
                 Mil/glass