Glass clad/polycarbonate structures that can be fabricated to pass stringent impact resistant tests for hurricane resistant window qualifications and/or be used in security application such as bullet resistant side windows in automobiles. The window structure consists of two layers of glass held together with two sided adhesive tape. The function of the tape is to act as a resin diking system and to control the overall thickness of the glass composite. A polycarbonate film between the glass is held in place by a resinous adhesive. The polycarbonate film is smaller in length and width and essentially floats in the cured resin. Expansion and contraction of the polycarbonate film is not restricted in the highly flexible adhesive. Fatigue adhesion failure and subsequent delamination with time is virtually eliminated. The framing structure involves mechanically bonding the frame to the window structure via nylon shims. These shims are placed through holes in the frame and glass and fastened to the outside of the frame. With the assistance of metal rollers on the bottom of the frame, the structure can move freely about in the frame. This movement is restricted with sealants. Upon impact the framing structure will absorb some of the energy as well as keeping the window in the frame.

CROSS-REFERENCE TO RELATED APPLICATION 
This application claims the benefit of U.S. provisional application No. 
60/009,989 filed Dec. 4, 1995. 
FIELD OF THE INVENTION 
The invention relates to hurricane resistant glass lamination composites 
useful in windows and doors. 
TECHNOLOGY REVIEW 
The need for high impact windows for hurricane resistance has become of 
increased importance in the Caribbean Islands and in the coastal areas of 
the United States. States, such as Florida have experienced severe 
commercial and residential real estate losses, as well as loss of life due 
to the devastation caused by hurricanes, e.g. Andrew and Opal. This 
problem has spurred studies to ascertain how the effects of the high winds 
created by the hurricane can be minimized. The degree and type of damage 
in Jacksonville, Fla. and Charleston, S.C., which were subjected to direct 
hits by strong hurricanes were investigated. 
Based on these studies a number of recommendations for new construction and 
renovation for existing structures have been made by governmental and 
independent agencies. In addition to upgrading construction codes in high 
profile areas, replacement of current tempered windows by high impact 
windows was suggested. In Charleston, S.C., no failure of laminated 
windows were reported, whereas most windows with tempered glass failed. 
One theory of hurricane resistant windows is that, in the absence of high 
winds in the interior of a building, the roof and walls of said building 
will remain intact and therefore minimize damage. Although this theory is 
controversial, the Florida State Building Code Agencies in Dade and 
Broward counties have instituted new requirements for high impact windows. 
These new codes have been spurred on by insurance companies who insist 
these changes in window codes must be made or commercial and residential 
insurance rates will dramatically increase. Some insurance companies have 
already left the state of Florida and others have threatened to follow 
suit. Resistance to these changes have come from the construction 
companies who feel these changes would severely and negatively impact new 
construction in Florida due to the high cost of these windows versus 
double framed float glass or tempered glass. 
High impact windows have traditionally been used in the automotive market. 
Windshields in automobiles must be capable of preventing bodily harm to 
the driver and passengers in the car. Requirements include not only that 
the object not enter the interior of the car, but the glass laminate must 
remain in place, and in the event that the occupants of the car hit the 
windshield with their heads that the impact be soft (the laminate must 
have absorbing properties). In other words, the glass laminate windshield 
must be capable of flexing in either direction from impact and remain in 
place. This type of glass laminate construction contains a flexible 
plastic film interlayer. In addition to flexibility and toughness, the 
plastic interlayer must be optically clear and remain invisible to the 
observer over 10-20 years in the field (no yellowing or delamination). 
This type of film product has been in use in automobile construction for 
the past 50 years and has performed without significant problems. However, 
the side and back windows have been made from tempered glass and not glass 
lamination. Tempered and heat strengthened glass will sustain impacts, but 
once breached will catastrophically fail, although the particles of glass 
from this structure are not sharp and will not cut the occupants of the 
car. In the event of a car crash, the side and rear windows of tempered 
construction will shatter, allowing easy exit from the car. 
Glass film lamination has been successfully used in a variety of 
applications including sliding glass doors, slope glazing, bullet 
resistant structures, insulation and sound deadening, to name a few. 
However, application of film technology to the construction of hurricane 
resistant glass has some compelling problems, both from a production and 
performance criteria. 
SUMMARY OF THE INVENTION 
A hurricane resistant window/door structure has now been developed that 
combines an impact resistant window structure with a unique framing system 
that will not only prevent wind and flying debris from entering the 
enclosed structure, but assists in keeping the glass structure in the 
frame. 
A polycarbonate film is cut 1/4" smaller in length and width than the glass 
piece. Catalyzed resin is placed above and below the film (20-30 mils). 
The film essentially floats in the adhesive resin with the glass pieces 
surrounding both the resin and film. This configuration allows the 
polycarbonate to freely expand in three dimensions in the very flexible 
cured resin system. This configuration virtually eliminates the tendency 
of polycarbonate structure to delaminate from plastic adhesives due to 
excessive expansion and contraction.

DETAILED DESCRIPTION OF THE INVENTION 
In order to pass the impact test, the glass structure has to remain in the 
frame. A highly flexible silicone adhesive that bonds the glass to the 
aluminum or steel frame may be used. Although the adhesive is slow to cure 
and expensive, upon impact the glass structure does remain in the frame. 
Unfortunately, the silicone adhesive does tend to embrittle with time and 
performance is affected by temperature as well as time. 
An improved method has now been developed that allows the window to flex 
upon impact. The preferred window frame is based on wood and approximately 
1/8" to 1/4" wider than conventional metal frames. Holes are drilled into 
the wood frames and glass structures (see FIG. 1). The window is attached 
to the frame with nylon shims. Steel rollers at the bottom of the frame 
allows the window structure to slide in the frame (maximum movement is 
1/4"). The window structure is placed snug against the other section of 
the frame where impact would take place. The space between the glass and 
inner section of the frame is then filled with semi-flexible urethane foam 
or similar other flexible sealants. The foam or sealant acts as restraints 
from glass movement but upon impact will act as an energy absorbing agent. 
The wood frame and the foam will contribute insulation properties to the 
window. The structure makes it virtually impossible for the window to come 
out of the frame upon impact. Neither temperature or time affect 
performance. 
Insulated windows can easily be fabricated by using a second window with an 
air space in the conventional manner. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
A polyester resin was prepared according to the procedure stated in U.S. 
Pat. No. 5,318,853, example I, incorporated herein by reference. The 
liquid resin has the following properties: 
______________________________________ 
Color: A.P.H.A. 50 max. 
Brookfield Viscosity @ 25.degree. C.: 
330 cps 
Monomer Content: 42.0% 
Specific Gravity: 1.038 
Moisture (Karl Fischer): 
875 ppm 
Room Temperature Reactivity: 
100 gms 
(1% M.E.K.P. 9, catalyst: 1% silane adhesion promoter) 
Gel Time: 55 min. 
Peak Exotherm: 96.5.degree. F. 
Cure Time: 155 min. 
Total Time: 210 min. 
______________________________________ 
This resin acts as an adhesive in the glass lamination composites according 
to the present invention. The cured adhesive resin has the following 
properties 
______________________________________ 
Color (30 mil casting): 
A.P.H.A. 30 max. 
Tensile Strength, psi: 
1,250 
% Elongation: 130 
% Area Shrinkage: 
4-5% 
______________________________________ 
Procedure 
I. Glass 
Two pieces of float glass are cut usually to a square or rectangular shape 
for a window or door, and cleaned with industrial cleaner and washed 
thoroughly with hot water. After drying, two sided tape is applied (60 mil 
in thickness) to the edge of one of two pieces of cleaned glass. The 
protective coating is left on the tape. The surfaces of both glass pieces 
are treated with a 5% solution of phosphoric acid in water and wiped dry. 
The glass with the tape applied is laid flat for resin addition. Thickness 
of the glass is 90 mil (single strength). The glass side that receives the 
resin should be the air side of the float glass. As those in the art are 
aware, float glass is made by "floating" a layer of molten glass on molten 
"tin." Hence, the side of the glass product facing the molten metal is the 
"tin" side and the opposite side is the "air" side. The outside glass 
surface should be the tin side, as determined by an ultraviolet lamp. The 
polycarbonate film (10 mils) is cut to size (1/4" smaller in length and 
width than the glass) and the protective film is removed. The film is 
placed in an oven for 24 hours at 250.degree. C. After removal from oven, 
and while still warm, the film is wiped with an alcohol solution 
containing low levels of adhesion promoter. Removal of the liquid is 
quickly performed. 
II. Resin Catalysis: 
The resin is measured volumetrically to fill the space between the glass 
and polycarbonate film to a thickness of 30 mils. Adhesion promoter and 
catalyst is added at 1 pph each to the resin. 
The mix is stirred by bubbling in nitrogen. The whole is then placed in a 
vacuum chamber where the entrained and suspended bubbles are removed (5-10 
minutes). The amount of resin mix is adjusted to create 30 mils of resin 
interlayers between the glass and the polycarbonate film. 
III. Addition of Catalyzed Resin and Film to the Glass. 
A glass-moving suction cup is applied to the bottom-middle of the glass 
piece with the tape. The catalyzed resin is poured in the middle of the 
glass which has been pulled down. The film is now laid in the resin puddle 
and positioned to be as even with the glass as possible. The second resin 
mix is added to the top of the film and spread as evenly as possible. 
IV. Completion of the Laminate 
The protective coating of the tape is removed and a second piece of glass 
is applied in an overlap position. The glass-moving suction cup is removed 
and needle probes are placed at all four corners. 
V. Removal of air 
A heavy piece of glass is placed on the laminate and air escapes through 
the needle probes. Some resin flash occurs. The needle probes are removed. 
Any air bubbles at the tape are removed by use of needle syringes. After 
one to one and a half hours, the glass structure can be placed in a warm 
room at 100.degree.-110.degree. F. After 24 hours, the glass laminate is 
ready for further modification. 
Framing Structure 
Holes are drilled through the glass laminate using a water jet cutter at 
the outer edge of the tape. The holes are perpendicular to the glass. At 
least five holes on the long side and 2 or 3 holes on the short side are 
necessary. A wooden frame is fabricated in which the glass laminate fits 
in tightly on one side. The thickness of the frame is 1/2". Holes 
corresponding to the holes in the glass are drilled perpendicular to the 
wooden frame to register with the holes drilled in the glass laminate. 
Nylon shins are placed through the holes in the wooden frame and the glass 
laminate and fastened on one side. The laminate rests on metal rollers so 
that the whole structure can move laterally. With the structure flush 
against one side of the frame, flexible foam is sprayed into the 1/4" 
space between the laminate and frame. After the foam has cured, tape can 
be applied to mask the foam. (See FIG. 3) 
Impact testing is done at the front of the frame. This structure passes the 
2".times.4" Impact Test with only minimal spalling occurring on impact. In 
some cases, the back piece of glass does not break. 
Impact Resistant Testing. Polycarbonate is marguarded on the inside 
surface. 
Configuration A 
90 mils glass, 30 mils Resin A, 10 mils polycarbonate film, 30 mils resin 
A, 90 mils glass. 
Configuration B 
90 mils glass, 30 mils resin A, 30 mils polycarbonate film, 30 mils resin 
A, 90 mils glass. 
Configurations of glass clad/polycarbonate structures that allow passage of 
Level 1 Bullet Resistant testing, A.S.T.M. 1792. 
Configuration C 
90 mils glass, 30 mils resin A, polycarbonate casting (1/8 inch). 
Configuration D 
1/4 inch glass, 30 mils resin A, 60 mils polycarbonate film. 
Configurations of glass clad/polycarbonate structures that allow passage of 
Level 2. 
Configuration E 
1/4 inch glass, 30 mils resin A, polycarbonate casting (1/4 inch) 
Configuration F 
1/4 inch glass, 60 mils resin A, polycarbonate film (1/8 inch). 
Glass Clad/Polycarbonate Adhesion and Environmental Testing 
1. Tensile Adhesion 
One sample of 1/8".times.1/8" polycarbonate laminates were tested. The 
sample was prepared by laminating two 12".times.12" with 30-35 mls of 
uncoated polycarbonate treated in a similar manner to the glass clad 
polycarbonate laminate previously prepared. After three days at room 
temperature, three samples were tested. Also tested were three samples 
each of the samples subjected to 0.degree. C. for 24 hours and the three 
samples post-cured at 80.degree. C. for five hours. The results are below: 
______________________________________ 
R.T. 0.degree. C. 
80.degree. C. 
100.degree. C. 
______________________________________ 
Average values 
1425 1380 1510 870 
of 3 samples (psi) 
______________________________________ 
2. Environmental Testing 
12".times.12".times.30 mL samples were prepared as described above. The 
samples were then cured at 80.degree. C. for five hours. Three samples 
were placed in a freezer for 24 hours and then brought to room temperature 
for four hours. The samples were then placed in an oven at 125.degree. C. 
for 24 hours. This process was repeated eight times. At no time was any 
delamination observed between the polycarbonate and glass. 
Hurricane Resistant Requirements 
In order to simulate the environment of a Class 5 hurricane (most severe), 
tests were devised to meet such requirements. 
A. Impact Test 
A seven foot 2".times.4" piece of wood is fired from a aluminum cannon in 
which the force propel the missile is generated by compressed air. 
B. Cycling Test 
During a hurricane, pressures may vary dramatically. To simulate these 
conditions, the window is cycled after the impact test from pressure to 
vacuum. Failure represents loss of vacuum or loss of pressure. 
C. Pressure Testing 
To measure the strength of the window construction, high pressure is 
continually applied until failure. Usually, a minimum pressure rating is 
required. 
D. Fire Testing 
All candidates must submit samples for the following tests: 
1. Tunnel Test, A.S.T.M. E-84 
Pass=75 flame spread (max.), 450 smoke (max.) 
2. Vertical Burn, A.S.T.M. D 635 
Pass=self-extinguishing 
3. Self Ignition A.S.T.M. 1929 
Pass=600.degree. F. (min.) 
E. Weathering Testing 
1. Xenon Arc Exposure=A.S.T.M. G26 utilizing a 6500 watt lamp for 4500 
hours 
Pass=no delamination or yellowing. 
Bullet Resistant Applications 
Although the glass lamination approach was designed for Hurricane Resistant 
application, the approach can be used for bullet resistant applications. 
For example, the system can be applied to side windows in automobiles for 
protection against drive-by shootings. By varying the thickness of the 
polycarbonate, a glass clad/polycarbonate window can be designed to offer 
various levels of bullet resistant protection. In the case of bullet 
resistant applications, glass can not be used inside due to severe glass 
spalling. The inside surface of the glass window laminate must be 
marguarded polycarbonate. 
Typical structure and level protection are illustrated below: 
Configurations: 
1. Type 1 
90 mils glass, 30 mils resin, 10 mils polycarbonate 
2. Type 2 
90 mils glass, 30 mils resin, 30 mils polycarbonate 
3. Type 3 
90 mils glass, 30 mils resin, 60 mils polycarbonate 
4. Type 4 
1 inch glass, 30 mils resin 1/8 inch polycarbonate 
5. Type 5 
3/8 inch glass, 30 mils resin, 1/4 inch polycarbonate 
6. Type 6 
1/2 inch glass, 30 mils resin, 1/2 inch polycarbonate 
Levels: 
1. 1201 CRF Category 11 
2. Level 0--3 shots with 32 caliber pistol 
3. Level 1--3 shots with 9 millimeter pistol 
4. Level 2--3 shots with 357 magnum pistol 
5. Level 3--3 shots with 44 magnum rifle 
6. Level 4--4 shots with 40 odd 6 rifle 
Results: 
1. Type 1--passes 1201 CRF Category 11 
2. Type 2--passes Level 0 
3. Type 3--passes Level 1 
4. Type 4--passes Level 2 
5. Type 5--does not pass Level 3 but the missile does not have killing 
power 
6. Type 6--does not pass Level 4 but the missile does deflect the first 
bullet but not the second or third. 
The object of bullet resistant side windows in cars is to prevent 
fatalities with the thinnest and least costly glass laminate structure. 
For most pistol protection, either 60 mils or 1/8 mil polycarbonate films 
or castings will suffice. 
Advantages of the glass/resin/polycarbonate/resin/glass composite: 
1. The system has at least one glass side so that scratch resistance on 
that side is not a problem. 
2. A relatively low cost system which can be automated to produce high 
volumes of laminated impact glass. 
3. This specific resin based on tertiary butyl styrene possesses low 
shrinkage properties that allow for excellent adhesion to polycarbonate 
without affecting visual properties. 
4. The cold cure lamination process does not require heat, pressure or UV 
radiation during fabrication. 
5. The framing structure not only presents the structure from coming out of 
the frame but also absorbs some of the impact energy. Thus, less glass 
spalding occurs. 
It is understood that various other modifications will be apparent to and 
can readily be made by those skilled in the art without departing from the 
scope and spirit of this invention. Accordingly, it is not intended that 
the scope of the claims appended hereto be limited to the description as 
set forth herein, but rather that the claims be construed as encompassing 
all the features of patentable novelty that reside in the present 
invention, including all features that would be treated as equivalents 
thereof by those skilled in the art to which this invention pertains.