SYSTEMS OF UNION OF POINT FOR LAMINATED GLASS AND PROCEDURES FOR ITS PREPARATION
BACKGROUND OF THE INVENTION Laminated glass can be useful in houses and buildings; as a protection in cabinets and on presentation shelves; and other articles where improved safety performance is desirable in glass. In architecture, it can have advantages by joining glass to frames and supporting structures of buildings by means of direct point support systems using bolts or other non-adhesive fasteners. For example, a system of glazing by bolts allows the design of a large viewing area, and highly transparent facades. The patent of E.U.A. No. 4,406,105 and the patent of E.U.A. No. 4,680,206 as well as EP No. 0 735 227 Bl discloses the use of point joining systems for structural glass assemblies. The production of glazing systems that can be clamped to support structures by means of joining at a direct point (hereinafter "screwed glass") is not without problems. The use of bolted glass systems can be difficult to the various factors inherent in a conventional bolted glass process. For example, screwed glass systems
Ref. 160574 require the use of tempered glass, which results in reduced optical clarity and presents a risk of spontaneous rupture due to nickel sulphide incisions and deep scratches induced when in use. Conventional laminated safety glass generally comprises a thermoplastic laminate bonded between the sheets of glass or other transparent plastic materials. These laminated glass compounds are required to meet stringent requirements that include performance against impact, weather resistance and transparency. However, the presence of a polymeric intermediate layer can also generate difficulties when using screw-in glasses. If the glass is broken accidentally, the union of the screwed system is maintained by clamping through random glass fragments minimally attached to the intermediate layer. The concentrated connecting forces that are characteristic of screwed glass often cause the broken glass fragments to cut through the intermediate layer and therefore divide the connection between the screwed glass laminate and the building support structure. This cut of the intermediate layer is exacerbated at high temperatures of 50 ° C and higher due to the dragging of the intermediate layer. This operation demand is manifested in a reduced integrity to the breaking of the glass-laminated glass studs screwed after accidental breaking of the glass. Another concern when using bolted glass laminates is to keep the holes in the intermediate layer aligned with the holes in the glass during the rolling process. The Patent of E.U.A. No. 5,787,662 describes elaborate construction elements that attempt to correct this problem of hole alignment between glass layers. There are still additional problems that arise with laminated glass systems bolted in relation to the compatibility between the intermediate layer and the fastener, as well as the durability of the joint. The problems of delamination of the intermediate layer-glass are usually observed around the connecting holes that are required to accommodate the bolt fittings. When bolted laminated glass is used for increased safety, a glass layer and a polymer intermediate layer are often treated as redundant structural components. EP 0 651 113 Bl calls for a joining system for bolted glass laminates that structurally uses a glass layer only in the laminate. The patent application of E.U.A. 2002/0020119 Al describes the use of special fastener attachment systems to allow the optimal design of bolted glass and bolted glass laminates.
It may be desirable to have a screwed glass laminate and a simple joining system that can solve the problems of conventional bolted glass and screw laminated glass systems. SUMMARY OF THE INVENTION In one aspect, the present invention is a direct-point bonding glazing system (bolted glass), comprising: (1) a polymeric intermediate layer, (2) in at least one glass sheet; (3) at least one receiver for a joining means; and (4) at least one attachment means, wherein the polymeric intermediate layer is bonded to at least one surface at least one glass sheet, and wherein at least one receiver is adhesively bonded to the glass by the layer polymeric intermediate so that the receiver is positioned to mechanically accept the joining means. In another aspect, the present invention is a method for preparing a glazing system suitable for direct point attachment to a support structure comprising the steps of: assembling a glass laminate comprising: (1) a polymeric intermediate layer, ( 2) at least one sheet of glass; (3) at least one receiver for a joining means; and (4) at least one attachment means, wherein the polymeric intermediate layer is bonded on at least one surface to at least one sheet of glass, and wherein at least one receiver is adhesively bonded to the glass by the polymeric intermediate layer in such a way that the receiver is positioned to mechanically accept the joining means. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a sectional view of a screwed glass system comprising first and second glass layers joined by a polymer intermediate layer and further comprising a cylindrical threaded receiver that is open at one end to receive a joining means and is closed at one end, wherein the receiver is embedded in the middle layer on all sides, with the exception of the open end which is exposed on the surface of the first glass layer, and where the receiver does not pass below the surface of the second glass layer. Figure 2 is a variation of Figure 1, except that the receiver further comprises a lip projecting from the lower portion of the second end of the receiver essentially parallel to the surface of the glass and fully embedded in the thermoplastic polymeric intermediate layer. Figure 3 is a variation of Figure 1, except that the receiver passes through both glass layers, the closed end of the receiver is in the same plane as the exposed surface of the second glass layer.
Figure 4 is a variation of Figure 3, except that the receiver further comprises a lip projecting from the lower portion of the closed end of the receiver essentially parallel to the surface of the glass. The lip is attached to the surface of the glass with a thin layer of polymer. Figure 5 is a variation of Figure 1, except that the receiver comprises a countersink geometry to allow mounting in the same plane with an internal glass surface. The countersink receiver wall is attached to the countersunk glass hole with a thin layer of the polymer. Figure 6 is a variation of Figure 5, except that the countersink receiver extends past an interior glass surface and is fully embedded in the polymeric intermediate layer. Figure 7 is a variation of Figure 5, except that the receiver comprises a countersink geometry to allow mounting in the same plane with an external glass surface. The countersink receiver wall is attached to the countersunk glass hole with a thin layer of polymer and the arrow of the receiver continues through the laminate and until the open end is in the same plane as the outer surface of the other layers of glass . The fastener connection is made at the open end of the receiver.
Figure 8 is a variation of Figure 3, except that the receiver is a double receiver that is open at each end of both exposed glass surfaces, and can accept a joining means for any of the glass surfaces. Figure 9 is a variation of Figure 8, except that the receiver in Figure 9 further comprises a lip projecting into the intermediate layer, interposed between the two layers of glass. Figure 10 is a receiving device that is embedded within the laminate and that is directly attached to the polymeric intermediate layer. Provides a solid internal surface * for attachment to a fastening device. Figure 11 is a variation of Figure 10 in which the receiver is again embedded in the laminate and has such dimensions that lie in the same plane as the edges of the hole. The connection is made to the fastener via a threaded surface in the receiver. DETAILED DESCRIPTION OF THE INVENTION Figure 1. is a sectional view of a system
(10) Screwed glass (fastened with bolts) comprising a first glass layer (14) and a second glass layer (16) joined together by a polymeric intermediate layer (18) and further comprising a receiver (12) equipped cylindrical which is open at one end to receive a joining means, and closed at one end, where the receiver is embedded in the middle layer on all sides with the exception of the open end which is exposed on the surface of the first glass layer and where the receiver does not pass below the surface of the second layer of glass. Figure 2 is a sectional view of a screwed glass system (20) comprising a first glass layer (24) and a second glass layer (26) which are joined by a polymeric intermediate layer (28) and which comprises a cylindrical threaded receiver 22 which is open at one end to receive a joining means and which is closed at one end, the closed end further comprises a lip (21) projecting from the lower part of the closed end, wherein the receiver is embedded in the middle layer on all sides, with the exception of the open end which is exposed on the surface of the first glass layer, and where the receiver does not pass below the surface of the second layer of glass . Figure 3 is a sectional view of a system
(30) Screwed glass comprising a first glass layer (34) and a second glass layer (34) which are joined by a polymeric intermediate layer (36) and further comprising a cylindrical threaded receiver (32) that is open at one end to receive a joint, where the receiver is embedded in the middle layer on all sides except for the open end, which is exposed on the surface of the first glass layer, and the closed end of the receiver which It is in the same plane as the exposed surface of the second glass layer. Figure 4 is a sectional view of a screwed glass system (40) comprising a first glass layer (44) and a second glass layer (44) which are joined together by a polymeric intermediate layer (46) and which further comprises a cylindrical threaded receiver (42) that is open at one end to receive a joint, and wherein the receiver is embedded in the intermediate layer on all sides with the exception of the open end, which is exposed on the surface of the first glass layer, and the closed end of the receiver which is essentially in the same plane as the exposed surface of the second glass layer and further comprising a lip (48) which is attached to the surface of the second layer of glass with a thin layer of the polymeric intermediate layer (46). Figure 5 is a sectional view of a system
(50) Screwed glass comprising a first glass layer (54) and a second glass layer (56) which are joined by an intermediate polymer layer (58) and further comprising a countersunk threaded receiver (52) that is open at one end to receive a joining means and which is closed at one end, in · where the receiver is mounted in the same plane with the inner surface of the first glass layer, and that it makes contact by means of the intermediate layer on all sides, with the exception of the open end, which is exposed in the surface of the first glass layer, and wherein the receiver does not pass below the surface of the second glass layer. Figure 6 is a sectional view of a screwed glass system (60) comprising a first glass layer (64) and a second glass layer (66) which are held together by a polymeric intermediate layer (68) and which further comprises a countersunk threaded receiver (62) which is open at one end to receive a joining means, and which is closed at one end, where the receiver is embedded in the intermediate layer on all sides with the exception of the open end which is exposed on the surface of the first glass layer, and where the receiver does not pass below the surface of the second glass layer. Figure 7 is a sectional view of a system
(70) Screwed glass comprising a first glass layer (74) and a second glass layer (76) which are joined by an intermediate polymer layer (78) and further comprising a countersunk threaded receiver (72) that is open at one end for receiving a joining means and which is closed at the end, wherein the open end of the receiver is mounted in the same plane as the external surface of the first glass layer and the closed end of the receiver is mounted on the same plane as the outer surface of the second glass layer, and is brought into contact by the intermediate layer on all sides, except for the open and closed ends which are exposed on the outer surfaces of the glass layers. Figure 8 is a sectional view of a screwed glass system (80) comprising a first glass layer (84) and a second glass layer (84) which are joined by a polymeric intermediate layer (88) and comprising in addition a cylindrical threaded receiver (82) that is open at both ends to receive up to two joints, wherein the receiver is embedded in the intermediate layer on all sides with the exception of the open ends which are exposed on the surfaces of the layers of glass, the ends of the receivers are in the same plane as the exposed surfaces of the glass. Figure 9 is a sectional view of the system
(90) Screwed glass comprising a first glass layer (94) and a second glass layer (94) which are joined by a polymeric intermediate layer (96) and further comprising a cylindrical threaded receiver (92) that opens at both ends to receive up to two joints, wherein the receiver further comprises a lip (93) projecting from the receiver, and the receiver is embedded in the middle layer on all sides, with the exception of the open ends which are exposed on the surface of the glass layers, the ends of the receivers are in the same plane as the exposed surfaces of the glass. Figure 10 is a sectional view of a screwed glass system (100) comprising a first glass layer (104) and a second glass layer (104) which are joined by a polymeric intermediate layer (106) and comprising furthermore a receiver (102) threaded into an opening (101) in the glass system, wherein the receiver provides a solid surface for joining a joining means, wherein the threads are interleaved from the opening. Figure 11 is a sectional view of a system
(110) Screwed glass comprising a first glass layer (114) and a second glass layer (114) which are joined by a polymeric intermediate layer (116) and further comprising an internal threaded receiver (112) within a opening (111) in the glass system, wherein the receiver provides a solid surface for joining a joining means, wherein the threads are in the same plane as the opening. In one embodiment, the present invention is a system for direct connection of a receiving system of an intermediate layer of resistant polymer. -In the case of accidental breaking of the glass, the integrity of the unit is maintained by transmitting any applied force, for example the own weight, the wind load and the like, through the polymeric intermediate layer and the receiver to the connection system with the building support system. This has a distinct advantage over conventional bolted laminated glass where the performance of the system is determined by the transmission of forces through the broken glass fragments. This latter condition is limiting insofar as glass fragments often lead to cuts and perforations of the intermediate layer and are often free of ruptures, particularly during cyclic loading, that is, when the force is emitted by a load in the laminate it cycles from a positive direction to a negative direction. Conventional bolted laminates are often observed to tear and pull loose their bolted couplings after accidental breakage. This problem is. exacerbates at elevated temperatures, especially higher than 50 ° C. Additional advantages of the systems outlined in Figures 1 to 9 include a decreased tendency to glass-polymer delamination in the vicinity of the hole since the contact surface between the glass and the polymer is essentially internally sealed from ambient humidity external, which can play a role in the mechanisms of delamination. The receiver systems outlined in Figures 1, 2, 5 and 6 require that only one hole is made in the glass layer and thus difficulties in aligning two holes in two different glass layers are eliminated. These receiver systems that are screwed to a single glass layer will also facilitate the manufacture of bolted glass where insulated glass units, such as double and triple glazing, are required for energy management. The bolted glass systems described herein allow all of the components-that is, the glass, polymer and receiver-to be included as structural elements in the design of bolted glass laminates for transparent structural facades. In another embodiment, the present invention is a glazing system comprising an intermediate polymer layer interposed between at least two layers of glass, wherein the glazing system can be joined to a support structure by direct point joining, wherein The direct point connection is by means of a receiver for a joining means, the receiver is embedded in the intermediate layer in such a way that it accepts the binding means for attachment to the support structure. The glass can be any of the standard types: annealed, heat strengthened or tempered, commonly used in architectural applications. The glass can be flat, curved or tapered without altering the practice of the present invention. A support structure, for the purposes of the present invention, may be the frame of a window, a building, a wall, a panel, a roof, a floor, suspension wires or any structure of a building or substructure having the function of supporting a load. A suitable joining means can be any means for joining the laminate to a support structure. The suitable joining means can be, for example, bolts, clamps, nails, screws, ropes, chains, retainers, snaps, clips and the like. With the proviso that the joining means is strong enough to form an appropriate support for the laminated structure. A suitable receiver can be any feature that works together with a joining means to form a link to a support structure. A suitable receiver of any generally resistant material can be constructed such as: metals such as steel, aluminum, titanium, bronze, lead, chromium, copper and the like; engineering plastics such as polycarbonate, polyurethane, nylon, polyacrylates (alkyl) poly (acetals) and the like; natural materials such as stone, wood or similar. The materials may be selected based on compatibility with the polymeric intermediate layer to minimize internal stresses in the laminate structure such as those that may result from incompatibilities between the glass, the receiver, or the polymeric intermediate layer. A suitable tough polymeric intermediate layer can be any that can form an adhesive bond with a glass and also with the building material used to form the receptor for the bonding medium. A suitable thermoplastic intermediate layer can be an acid copolymer formed by copolymerization of an ethylenically unsaturated carboxylic acid with ethylene, or an ionomeric polymer formed by total or partial neutralization of an acid copolymer. The acid copolymer or suitable ionomers can be purchased commercially from E.I. DuPont de Nemours and Company under the trade names Surl nMR or NucrelMR, for example. Particularly preferred are thermoplastic polymers consisting essentially of a water-insoluble salt of a copolymer of ethylene and methacrylic acid or acrylic acid containing 14-28% by weight of acid and having approximately 20-60% by weight of acid neutralized with sodium ion or zinc ion, or magnesium ion, or combinations thereof, and wherein the ionomeric resin has a melt index of about 0.5-50. A thermoplastic interlayer can also be polyvinyl butyredrigid having a low level of plasticization, or polyurethane. Preferably, a suitable polymer has a Young's modulus of storage of 100-1,000 MPa (mega Pascals) at 1.0 Hz and 25 ° C, determined in accordance with ASTM D 5026-95a. A suitable polymer intermediate layer can also be based on an in situ cured resin such as an acrylic or polyurethane system. Adhesion between the receptor and the thermoplastic intermediate layer can be chemically improved by treatment of the receptor with a chemical coupling agent such as silane-based compounds and the like. The adhesion between the receiver and the thermoplastic intermediate layer can be mechanically improved by corrugating the receiving surface by means of machining, knurling and sand spraying, and the like. The laminate can be manufactured according to known and conventional glass lamination techniques, with the exception that the laminate must have holes that will accept the receiver and the joining means, and the thermoplastic intermediate layer must form an adhesive bond with the surfaces of glass and also the receiver in such a way that the intermediate layer, the receiver and the glass surface are joined with a suitable adhesive force. The rolling temperatures may depend on the rolling conditions that include the pressure and the type of materials that are laminated. Temperatures above 100 ° C are typically required to obtain a laminate of the present invention. A person skilled in the art will know the rolling conditions suitable for use. Examples of manufacturing methods for thermoplastics include pre-press roll-up followed by autoclaving and vacuum bagging and autoclaving. Examples for resin laminates include cushioning of the components, addition of the liquid resin followed by curing with ultraviolet radiation, thermal curing or catalytically induced curing. EXAMPLES The following examples are presented to further illustrate the present invention. The examples are not intended to limit the scope of the invention in any way, nor should they be used to define the claims or specification in any way that is inconsistent with the invention as claimed or as described herein. Example 1 consists of a bottled glass receiving system as described in Figure 1. The system comprises a first and second glass layers that are joined by a copolymer ionomer of ethylene / acrylic acid, available from E.I. DuPont de Nemours and Company under the trade name of SentryGlasMR Plus, and which is additionally constituted in a stainless steel receiver for a joining means. The receiver having an open end for receiving a joining means and a closed end, is embedded in the intermediate layer on all sides, with the exception of the open end which is exposed on the surface of the first glass layer. The receiver does not pass below the surface of the second glass layer. The surface of the receptor in contact with the polymer is knurled to improve the mechanical adhesion between the steel and the polymer. The internal surface of the steel receiver is threaded for the joining means. The system is manufactured by assembling individual components and laminating by vacuum bagging when applying pressure at elevated temperatures. One method of ensuring good polymer flow around the receiver is to drill individual rings of DuPont SentryGlas ™ Plus with an internal diameter that matches the outer diameter of the receiver and an outer diameter that matches the internal diameter of the hole in the glass. The thermoplastic intermediate layer is built around the receiver with a series of DuPont SentryGlas1"Plus rings During the autoclave process, the molten thermoplastic intermediate layer flows and welds with the rest of the thermoplastic intermediate layer forming the largest part in the polymeric component Laminate-free laminates are produced that show good adhesion between glass, steel receiver and intermediate layer Example 2 consists of a screwed glass receiver system, a first and second glass layers that are joined by a Thermoplastic intermediate layer of DuPont SentryGlasMR Plus, as described in Figure 2. In this example, a stainless steel receiver is a variation of that used in Example 1, where an additional lip is manufactured at the closed end of the receiver The internal surface of the receiver is threaded for the joining means and the surface in contact with the polymer is knurled to promote see adhesion DuPont SentryGlas ™ Plus polymer rings are accumulated around the receiver during fabrication and a solid disk of DuPont SentryGlas ™ Plus placed on the bottom surface, where the lips extend. The receiver / DuPont SentryGlas ™ Plus assembly is assembled with glass and a DuPont SentryGlas ™ Plus interlayer sheet and laminated by vacuum bagging applying pressure at elevated temperatures. Example 3 consists of a bolted glass stainless steel receiver, a first and second glass layers that are joined together by a thermoplastic intermediate layer of DuPont SentryGlas1® Plus, as described in Figure 3, and is a variation of the example 2, except that the stainless steel receiver passes through both glass layers, the closed end of the receiver is in the same plane as the exposed surface of the second glass layer. The internal surface of the receiver is threaded for the attachment means and the surface in contact with the polymer is knurled to promote adhesion. The fabrication consists of drilling a hole in the intermediate layer DuPont SentryGlasMH Plus, assembling the rings of SentryGlasMR Plus around the receiver, assembly of the intermediate layer, rings, receiver and glass and lamination by wrapping and application to vacuum and application of pressure at elevated temperatures sufficient to cause the polymer to flow. Example 4 consists of a bolted glass stainless steel receiver, a first and a second glass layer which are joined together by a SentryGlas ™ Plus thermoplastic intermediate layer, as described in FIG. 4 and exhibits a variation of example 3, except that the receiver further comprises a lip projecting from the lower portion of the closed end of the receiver essentially parallel to the surface of the glass. The lip is attached to the glass surface with a thin layer of DuPont SentryGlas1 ^ Plus. The internal surface of the receiver is threaded for the attachment means and the surface in contact with the milled polymer to promote adhesion. The fabrication consists of drilling a hole in the intermediate layer DuPont SentryGlasMR Plus, assembly of the rings of DuPont SentryGlasMR Plus around the receiver that includes a ring of larger outside diameter to seal the lip to the upper surface of the glass, assemble the intermediate layer, the rings, the receiver and the glass and laminate by wrapping vacuum and application of pressure at high temperatures hot enough to cause the polymer to flow. Example 5 consists of a bolted glass stainless steel receiver, a first and second glass layers that are joined by a thermoplastic intermediate layer of SentryGlas ™ Plus, as described in Figure 5 and is a variation of Example 1, except that the receiver comprises a countersink geometry to allow assembly in the same plane with an internal glass surface. The internal surface of the receiver is threaded for a joining means. The countersunk receiver wall is attached to the countersunk glass hole with a thin layer of the DuPont SentryGlas ™ Plus intermediate layer. This is obtained by molding a thin cup washer from DuPont SentryGlas1 * Plus at elevated temperatures that conform to the profile of the countersunk receiver. The countersunk stainless steel receiver, the DuPont SentryGlasMR Plus cup washer, the DuPont SentryGlasMR Plus intermediate layer and the glass are assembled and laminated by vacuum wrapping and pressure application at elevated temperatures.
Example 6 consists of a bolted glass stainless steel receiving system, a first and a second glass layer which are joined together by a thermoplastic intermediate layer of DuPont SentryGlas ™ Plus, as described in Figure 7 and is a variation of Example 5 , except that the receiver comprises a countersunk geometry to allow assembly in the same plane with the external glass surface. The arrow on the receiver is knurled to promote adhesion and continue through the laminate until the open end is in the same plane as the outer surface of the other glass layer. The union of the threaded fastener is made at the open end of the receiver. The system is assembled by first adhesively bonding the countersunk portion of the receiver to a glass layer using an epoxy adhesive. The DuPont SentryGlas ^ Plus polymer rings accumulate around the cylindrical portion of the receiver. A hole is drilled in the DuPont SentryGlas ™ Plus intermediate layer, and the glass, receiver, and polymer system are assembled and laminated by vacuum cracking and applying pressure at elevated temperatures, high enough to cause the polymer to flow. Example 7 consists of a bolted glass stainless steel receiver system, a first and second glass layers that are joined together by a thermoplastic intermediate layer of DuPont SentryGlas Plus, as described in Figure 8, and is a variation of the example 3, except that the receiver is a double receiver that is open at each end to both exposed glass surfaces, and that is capable of accepting a joining means from any of the glass surfaces. The polymer contact surface of the receptor is knurled to improve the mechanical adhesion between the steel and the polymer. The inner surface of the steel receiver is threaded for the joining means. The fabrication consists of drilling a hole in the intermediate layer of DuPont SentryGlasMR Plus, assembling the rings of DuPont SentryGlasMR Plus around the receiver, assembling the intermediate layer, the rings, the receiver and the glass and laminar by vacuum wrapping applying pressure at temperatures high enough to cause the polymer to flow. Example 8 consists of a bolted glass stainless steel receiver system, a first and second glass layers which are joined by a thermoplastic layer of DuPont SentryGlas "11 Plus, as described in Figure 9 and which is a variation of the example 7, except that the receiver in Figure 9 further comprises a lip projecting into the intermediate layer interposed between the two layers of glass.The surface of the "receiver in contact with the polymer is knurled to improve the mechanical adhesion between the steel and the polymer. The inner surface of the steel receiver is threaded for a joining means. The fabrication consists of drilling a hole in the middle layer of DuPont SentryGlas ™ Plus, assembling the DuPont SentryGlas ™ rings around the receiver, the rings of DuPont SentryGlasME in contact with the inner lip extending past the diameter of the glass hole outside the diameter of the inner receiver lip. The diameter of the hole drilled in the intermediate layer is made to coincide with the lip of the internal receiver. The intermediate layer of DuPont SentryGlasMR Plus, the stainless steel receiver, the DuPont SentryGlasMR Plus rings and the glass are assembled and laminated by vacuum wrapping and applying pressure at elevated temperatures sufficient to cause the polymer to flow. Example 9 consists of a DuPont Delrin1 ^ poly (acetal) and screw glass receiving system, a first and second glass layers that are joined by a thermoplastic intermediate layer of DuPont SentryGlas ™ Plus, as described in Figure 10, where the receiving device is embedded inside the laminate and attached directly to the layer intermediate DuPont SentryGlasMR Plus. The receiver provides an internal solid surface for connection to a fastening device. The contact surfaces with the intermediate layer of the DuPont Delrin receiver "are knurled to improve the mechanical adhesion between DuPont Delrin and the intermediate layer of DuPont SentryGlasMR Plus." The internal surface of the DuPont Delrin "* receiver is a straight hole for a bonding medium . The system is assembled by first cutting a hole in the DuPont SentryGlas ™ Plus intermediate layer of equal diameter to the DuPont Delrin ™ receiver. Two thin discs of the intermediate layer DuPont SentryGlasMR Plus are placed on large flat surfaces of the DuPont Delrin ™ receiver and assembled with the intermediate layer DuPont SentryGlas ™ Plus and the glass. The assembly is laminated by vacuum wrapping and application of pressure at elevated temperatures, enough to cause the polymer to flow. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.