Abstract:
This invention relates to multiple glass/plastic laminates for ballistic resistant and security applications. The laminates typically comprise a glass lite and a plastic sheet, such as polycarbonate, bonded with an adhesive based on a novel solvent free thermosetting alkyd resin. Subsequent layers can be polycarbonate sheets and/or acrylic sheets and glass lites with the adhesive layer separating the lites and sheets. 
     Further, this invention relates to a vertical liquid pour process which enables the rapid manufacture of bullet resistant glass/plastic laminates without the need for expensive ultra-violet or heat curing ovens. The adhesive cures at temperatures ranging from 60° F. to 90° F. High temperature and high pressure treatments are unnecessary. Laminates produced in this manner with adhesive interlayer will pass all intended ballistic or security tests within a 12 hour period.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a division of application Ser. No. 07/916,714, filed Jun. 22, 1992, now U.S. Pat. No. 5,318,853 the entire specification of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the fabrication of multiple glass/glass, glass/plastic, and plastic/plastic laminates for ballistic resistant and security applications. 
     2. Technology Review 
     Glass laminates as related to the ballistic and security applications involve the construction of alternate layers of glass lites and plastic sheets with an adhesive interlayer. For the most part the interlayer has been a meltable film based on polyvinyl butyral. This polymer film has been the basis of substantially all safety glass applications in automobile windshields and commercial/residential windows requiring impact resistance. In some areas, however, problems exist that made the use of polyvinyl butyral film difficult at best. 
     Originally, bullet resistant glass consisted primarily of alternating layers of glass lites ranging in thickness from 1/8 to 3/8 and polyvinyl butyral film, that was 30 to 90 mils in thickness. Since the film contains 30% plastizer, the film rolls must be kept cool prior to use. The film is cut to the desired shape and placed between two lites of glass. The glass/film/glass composite is run through an oven in order to melt the film. Entrained air in the film is removed at this point by either vacuum or by roll compression. About 95% of the air is removed at this stage. The laminate is now subjected to 240-300F. temperature and 60-200 lb/sq. in. pressure in an autoclave to dissolve residual air, maintain film thickness and to achieve acceptable adhesion to glass. The production of multilayers of glass lites held together with polyvinyl butyral film is difficult at best. 
     With the introduction of tough, new plastics such as polycarbonate and acrylic sheets to replace some of the glass lites in order to produce light weight bullet resistant laminates, the problem associated with the use of polyvinyl butyral (P.V.B.) in multilayer applications became more severe. Adhesion of P.V.B. to the polycarbonate surface is marginal at best and delamination with time can occur. The high temperatures and pressures of the autoclave also can deteriorate the optical properties of the polycarbonate sheet. Alternative film development based on polyurethane has been commercialized and is currently offered as a replacement for P.V.B. in bullet resistant glass clad/polycarbonate composites. Although the adhesion to the polycarbonate has improved and impact strength is superior, air entrainment and increased costs vs. P.V.B. are disadvantages. Since the autoclave is still required, visual distorting of polycarbonates still can occur. Alternate urethane chemistry involves the application of a liquid, curable interlayer. In one case, the mix is comprised of two components-- an isocyanate prepolymer and a polyol crosslinker. Advantages of this system is high temperatures and high pressures treatment are not necessary. 
     Adhesion to the polycarbonate sheet is acceptable but the disadvantage is the removal of air when the liquid mix is introduced between the glass and polycarbonate sheets. Nominal thickness for bullet resistant glass clad polycarbonate sheets is 20-40 mils. A liquid mix with a viscosity greater than 300 cps. at 75° F. is extremely difficult to introduce in this space and at the same time remove entrained air. Other versions of urethane/acrylate modifications or methacrylate base liquid adhesives either etch the polycarbonate sheets or have severe air inhibition cure problems. 
     Unsaturated polyester resin systems have been used as liquid adhesives especially for television tube glass laminates. These types of resins can be formulated to have acceptable impact and energy absorbing properties for bullet resistant applications, but the major monomer employed in these types systems is styrene and styrene severely etches the surface of polycarbonate sheet, thus destroying the optical properties. 
     There have been prior patents regarding methods of making laminated glass using a liquid thermosetting resin. Two United States patents U.S. Pat. No. 3,703,425 to Delmonte and U.S. Pat. No. 4,234,533 to Langlands describe procedures for fabricating glass laminates using liquid thermosetting adhesives. 
     In the process described in the Delmonte patent, a flat glass lite is bowed in the center with a suction cup. Porous, double sided tape is applied at the edges of the glass. A second piece of glass is laid on top of the first. The double sided tape then seals the two pieces of glass together with a pool of resin between the lites in the center. The function of the tape is resin containment, thickness control and an outlet for entrapped air. A vacuum is applied around the glass lite. Air is removed through the tape pulling the resin to the tape. The glass laminate now remains flat until the liquid adhesive polymerizes to a solid. 
     In the process described in the Langlands patent, two lites of glass are adhered together with double sided porous tape at the edge on three sides. The fourth side is taped only on the edge of the lower plate. The protective film is partially removed. The two glass lites are fixed at a 45° angle. The resin is now introduced into a space between the lites. With 1/8 glass lites, the glass bows to accommodate the resin. As the glass composite is lowered to a flat position the resin fills the void with the entrained air escaping at the fourth side. Removal of the protective film allows the laminate to be completely sealed. Any remaining trapped air can be removed by applying pressure to the surface of the laminate. The entrained air either escapes through the porous tape or is removed with a needle syringe. 
     It is an object of this invention to provide an improved simple yet effective procedure for fabrication of glass clad/polycarbonate and acrylic bullet resistant laminates. 
     SUMMARY OF THE INVENTION 
     This invention relates to multiple glass/glass, glass/plastic, and plastic/plastic laminates for ballistic resistant and security applications. The laminates typically comprise a glass lite and a plastic sheet, such as polycarbonate, bonded with an adhesive based on a novel solvent free thermosetting alkyd resin. Subsequent layers can be polycarbonate sheets and/or acrylic sheets and glass lites with the adhesive layer separating the lites and sheets. 
     This invention relates to a vertical liquid pour process which enables the rapid manufacture of bullet resistant glass/plastic laminates without the need for expensive ultraviolet or heat curing ovens. The adhesive cures at temperatures ranging from about 60° F. to 90° F. High temperature and high pressure treatments are unnecessary. Laminates produced in this manner with adhesive interlayer will pass ballistic or security tests within a 12 hour period. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     A typical configuration of a level four bullet resistant glass/polycarbonate is illustrated in the Figure and as an example consisting of the following configuration: 1/4&#34;(G), 30 mils(A), 3/8&#34;(G), 30 mils(A), 1/4&#34;(P.O.), 30 mils(A), 1/4&#34;(P.C.), 30 mils(A), 3/8&#34;(G) , 30 mils(A), 1/8&#34;(G) 
     A=adhesive 
     G=glass 
     P.C.=polycarbonate 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The glass and polycarbonate sheet are placed on edge and bonded together on three sides with double sided 30 mil tape. The edges of the glass/polycarbonate are heat bonded with polyisobutyl rubber strips. See the Figure. This invention is not, however, limited to this configuration. Combinations with only plastic sheets, combinations with only flat glass, and any other combination of plastic sheets and flat glass known to those skilled in the art can be used as an effective ballistic or security laminate. 
     An example of the process or method of making such laminates is as follows. As many as five to ten such configurations can be placed in a row on a wooden stand with slats running perpendicular to the edges of the laminate. The glass/plastic layers are connected on three sides with double sided tape. The edges are heat sealed with polyisobutyl rubber strips and the whole is placed vertically on its edge. Foamed rigid sheets are clamped on either side of the multiple laminates to prevent bowing of the laminates when the resin is introduced. The catalyzed resin is introduced into the space between the glass and plastic layers at the untaped open edge at the top. With the laminate in the vertical position, the resin easily enters the space between the glass and plastic sheets. Entrained air quickly comes to the surface and dissipates. After filling, the mix is allowed to react. 
     When the resin level reaches the top, further resin addition ceases. Cure temperature range preferably range from about 50 to about 100° F., and most preferably from about 60° F. to about 90° F. and the cure is complete within about a 12  hour period. The foamed sheets are removed about one hour after resin introduction to allow for heat dissipation. After the resin has cured, the top part of the laminate is heat sealed with polyisobutyl rubber strips. After 12 hours of curing, the laminate is ready for testing. The advantages of this fabrication technique include: 
     1. Ambient temperature cure. 
     2. Single rapid resin pour with rapid air removal. 
     3. Two component mix or optional three component mix. 
     4. Inexpensive fabrication equipment. 
     The production of these laminates is, however, not limited to just this method and can be produced by any of a number of methods known to those skilled in the art. There are alternative methods of fabricating, utilizing the basic approach of single pour of liquid resin between multiple layers of glass lite and/or plastic laminates. 
     Probe Method 
     The method allows for the automated and rapid addition of catalyzed resin between the glass/plastic interlayers with rapid air removal. This method is designed for the rapid production of large, multiple glass/plastic structures. 
     The glass/plastic structure are cut to size. Two sided, 1/8 wide tape is applied as before to the edges of structures. The structures are connected via the tape while on edge producing a composite structure. Distance between the structures is determined by the thickness of the tape. The tape, in this case, is not permeable. Unlike the previously described procedure, the structures are taped on all four sides. The polyvinyl butyl rubber is applied to all four sides. Resin probes are introduced at the top, right side through the rubber and tape seals. Catalyzed resin is introduced under pressure via these probes. Air removal is accomplished via vacuum probes introduced at the top, left side. When the void between the glass/plastic structure are filled, the probes are removed. As before, the mix is then allowed to react. 
     All liquid resin utilized in all of these procedures is fully described in my parent application Ser. No. 07/916,714, now U.S. Pat. No. 5,318,853, the entire disclosure of which is incorporated herein by reference. 
     In order that persons in the art may better understand the practice of the present invention, the following Examples are provided by way of illustration, and not by way of limitation. Additional background information known in the art may be found in the references and patents cited herein, which are hereby incorporated by reference. 
     
         ______________________________________EXAMPLES   moles mol. wt. mole wt. % charge                                  gms.______________________________________Example I Base Resin-flexibleOligomer FormationReactantswater     1.25     18.0     22.5   1.49   59.6maleic    1.00     98.0     98.0   6.48   259.2anhydridephthalic  1.60    148.0     236.8  15.66  626.4anhydrideadipic acid     3.00    146.0     438.0  28.96 1158.4dipropylene     4.50    134.0     603.0  39.87 1594.8glycolpropylene 1.50     76.0     114.0  7.54   301.6glycol                     1512.3 100.00 4000.0gms.Stabilizer:   100 ppm (ethoxylated phosphoric acid);   Albrastab 190 (Albright/Stevens Corp.)Example II Base Resin-flexiblewater     1.25     18.0     22.5   1.71   68.4maleic    1.00     98.0     98.0   7.46   298.4anhydridephthalic  1.60    148.0     236.8  18.07  722.8anhydrideadipic acid     3.00    146.0     438.0  33.33 1333.22-methyl-1,3propane diol     4.50     90.0     405.0  30.81 1232.4propylene 1.50     76.0     114.0  8.67   346.8glycol                      1314.3 100.00 4002.0gms.Stabilizer:   100 ppm (ethoxylated phosphoric acid) -   Albrastab 190 (Albright/Stevens Corp.)Calc. Theo. H.sub.2 O removed = 539.8 gms.Cook Procedure (Examples I and II)______________________________________ 
    
     All ingredients are added to a 4 L. resin kettle equipped with mechanical stirrer, packed column, thermocouple, and an inert gas blanket inlet. The mix is heated with an electric mantle while stirring under an inert gas blanket at 200° C. until the acid number of the mix is 50 or below. An inert gas sparge is applied and the mix is cooked until the acid number is 15 or below and the Gardner viscosity is between a B and C (60% solids/40% styrene). 
     The solids are cooled to 150° C. and thinned with 25% butyl styrene with additional cooling. Tolylhydroquinone (30 ppm based on total resin mix) is added to the t-butylstyrene prior to thinning. 
     
         ______________________________________   moles mol. wt. mole wt. % charge                                  gms.______________________________________Example III Base Resin-semi-flexiblewater     2.25     18.0     40.5   2.81   112.4maleic    2.0      98.0    196.0   13.57  542.8anhydrideadipic acid     3.60    146.0    438.8   30.33 1218.2(Exxon)dicyclopenta-     0.40    132.0     52.6   3.64   145.6dienedipropylene     4.50    134.0    603.0   41.76 1670.4glycolpropylene 1.50     76.0    114.0   7.89   315.6glycol                      144.1  100.00 4000.0Stabilizer:   100 ppm (ethoxylated phosphoric acid) -   Albrastab 190 (Albright/Stevens)Calc. Theo. water removed = 467.0 gmsExample IV Base Resin-semi-flexiblewater     2.25     18.0     40.5   3.20   128.0maleic    2.00     98.0     196.0  15.47  618.8anhydrideadipic acid     3.60    146.0     438.8  34.57 1382.8(Exxon)dicyclopenta-     0.40    132.0     52.6   4.15   166.0diene2-methyl-1,5     6.00     90.0      540.0                              42.62 1704.8pentane diol                      1267.1 100.01 4000.4Stabilizer:   100 ppm (ethoxylated phosphoric acid) -   Albrastab 190 (Albright/Stevens)Calc. Theo. Water removed = 582.5 gms______________________________________ 
    
     Cook Procedure (Examples III and IV) 
     All ingredients are added except dicyclopentadiene. With the same type of equipment set up as in Examples I and II, the mix is heated to 200° C. and reaction water is removed until acid number is 50 or below. At this point the process is cooled to 170° C. and the dicyclopentadiene is added in 2 shots over a 45 minute period. After a 2 hour hold period at 170°-180  C., the whole is placed on main vent and sparged until the acid number is 14-18 and the GardnerHolt viscosity is 60% solid and 40% styrene equals B-C. From this point on all else remains the same as in Procedures for Examples I and II. 
     
         ______________________________________   moles mol. wt. mole wt. % charge                                  gms______________________________________Example V Polyester Polyol-Silyateddimethyl  1.000   174      174.0  46.51  1860.4adipatediethylene     1.250   106      132.5  35.42  1416.8glycoltetraethoxy     0.325   208       67.6  18.07   722.8silane                      374.1  100.00 4000.0Catalyst: Titanate catalyst: 500 ppm (Tyzor T. E.-Dupont)Calc. Theo. methanol distillate: 684.2 gmsCalc. Theo. ethanol distillate: 22.70 gmsExample VIdimethyl  1.00    174      174.0   49.14 1965.6adipate2-methyl, 1,3     1.250    90      112.5   31.77 1270.8propane dioltetraethoxy     0.325   208       67.6   19.09  763.6silane                      354.1  100.00 4000.0Catalyst: Titanate Catalyst (Tyzor T. E.-Dupont)Calc. Theoretical methanol distillate: 684.2 gmsCalc. Theoretical ethanol distillate: 22.70 gms______________________________________ 
    
     Process Procedure (Examples V and VI) 
     All ingredients except tetra ethoxy silane are added to a 4 L. resin kettle equipped with mechanical stirrer, packed column, thermocouple, and an inert gas blanket inlet. The mix is heated with an electric mantle while stirring under an inert gas blanket at 200° C. until the Gardner-Holt viscosity is A-B. The whole is cooled to 50°-60° C. and the silane is slowly added to the whole. After a 2 hour hold period, the kettle is placed on main vent and the mix is sparged until the Gardner-Holt viscosity is G-H. The silylated polyester polyol is cooled to 60° C. and discharged. Cook Specifications (Example V and VI) 
     1. Polyol Color: 100 A.P.H.A. max. 
     2. Viscosity (Brookfield) at 25° C.: 1600-1800 cps 
     3. Molecular Weight (G.P.C.) range: 3000-4000. 
     4. Residual glycol&gt;0.1% 
     
         ______________________________________Typical Glass Lamination Resin Formulations for Glass Clad/Plastic Applications, e.g. polycarbonate and or acrylic______________________________________sheetExample VII - non-fire retardant1.  Example I (25% t-butyl styrene)                         66.7 pph2.  t-Butyl styrene (Deltex)  21.3 pph3.  Styrene (Monsanto)        5.0 pph4.  2-ethyl hexyl methacrylate (Bayer)                         2.0 pph5.  Example VI                5.0 pph6.  Cobalt napthenate, 12% active (Mooney)                         180.0 ppm7.  Copper napthenate, 6% active (Mooney)                         20.0 ppm8.  Lithium octoate, 2% active (Mooney)                         1500.0 ppm9.  Nonyl Benzyl, trimethyl ammonium chloride                         50.0 ppm10. Tinuvin 328 (Ciba/Geigy)  1500.0 ppm                         100.3250Specifications:1.  Color, A.P.H.A.           50 max.2.  Viscosity, Brookfield, 25 C.                         150 cps.3.  Refractive Index          1.5250-1.5270Reactivity:   1 gram of a mixture of   50% methy ethyl ketone   peroxide (8% active) +   50% 2,4-pentanedione   peroxide with 99 gms of   above formulation.Gel time = 40 minutesPeak, °F. = 115Cure time = 100 minutesTotal time = 140 minutes______________________________________ Bullet resistant laminate made from the above are capable of passing Level 1 through Level 4 depending on ballet resistant testing configuration of glass and polycarbonate sheets, (AS -12). 
    
     
         ______________________________________Example VIII - fire retardant______________________________________1.  Example II (25% tbutyl styrene)                         66.7 pph2.  Dibromostyrene            25.3 pph3.  2-ethyl hexxl methacrylate (Bayer)                         3.0 pph4.  Example VII               5.0 pph5.  Cobalt Naphthenate, 12% active (Mooney)                         180.0 ppm6.  Copper Naphthenate, 6% active (Mooney)                         20.0 ppm7.  Lithium octoate, 2% active (Mooney)                         1500.0 ppm8.  Nonyl Benzyl, trimethyl ammonium chloride                         50.0 ppm9.  Tinuvin 328 (Ciba-Geigy)  1500.0 ppm                         100.3250______________________________________ 
    
     Above formulation is designed for attack glass applications. Specifications: 
     
         ______________________________________Specifications:1.  Color, Gardner            2 max.2.  Viscosity, Brookfield, 25 C.                         250 cps3.  Refractive Index          1.5320-1.5360Reactivity:   1 gm mixture of 75% M.F.F.P. (8% active)   25% 2,4 Pentadione perioxide   99 gms of F.R. FormulationGe; Time: 55 minutesPeak Exotherm, 0° F.: 125 F.Cure time: 140 minutesTotal Time: 195 minutesExample IX - Casting Application1.  Example IV               66.7     pph2.  t-butyl styrene (Deltec) 21.3     pph3.  Styrene (Monsanto)       5.0      pph4.  2-ethyl hexyl methacrylate (Bayer)                        2.0      pph5.  Example VI               5.0      pph6.  Cobalt naphthenate, 12% Active (Mooney)                        200.0    ppm7.  Cu naphthenate, 6% active (Mooney)                        20.0     ppm8.  Lithium octoate, 2% active (Mooney)                        1500     ppm9.  Tinuvin 328 (Ciba-Geigy) 1500     ppm                        100.3250Specifications1.  color A.P.H.A.            100 max2.  Viscosity, Brookfield, 25 C.                         150 cps3.  Refractive Index          1.5250-1.5270Reactivity:   1 gm of a mixture of 75% M.E.K.P. (8% active)   25% 2,4 pentane dione perioxide   99 gms of Casting formulationGel Time = 25 minutesPeak Time, F. = 130Cure Time = 90 minutesTotal Time = 115 minutes______________________________________ 
    
     The above formulation can be used in thick casting applications for bullet resistance. 
     It is understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of the present invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description set forth above but rather that the claims be construed as encompassing all of the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains.