FR2553083A1 - GLAZING AND METHOD OF MANUFACTURING - Google Patents

Abstract

THE INVENTION CONCERNS A PREFORMED ASSEMBLY OF A TRANSPARENT SHEET AND A JOINT GLUED TO ITS PERIPHERY, AS WELL AS THE PROCESS FOR MANUFACTURING THIS ASSEMBLY. THE SEAL 22 IS IN THE FORM OF A MATERIAL BASED ON THERMOSETTING POLYURETHANE, MOLDED ON THE PERIOD OF THE SHEET 20, WHICH IS ADVANTAGEOUSLY IN GLASS. THE MOLDING IS CARRIED OUT BY INJECTION IN A MOLD CAVITY AND THE PRESSURE, RESULTING FROM THE POLYMERIZATION, MAKES THE SEAL MATERIAL IN INTIMATE CONTACT WITH THE CAVITY OF THE MOLD AND WITH THE SHEET. FIELD OF APPLICATION: MANUFACTURE OF WINDSHIELDS, REAR GLASSES AND OTHER WINDOWS FOR VEHICLES AND OTHERS.

Description

The invention relates to a window assembly and its method of

  The invention relates more particularly to a window assembly comprising a sheet of optically-transparent material, such as glass, and a seal made of polymeric material, which is polymerized and cured on the spot in order to coat the marginal peripheral edges of the sheet. The joint may be configured to form a vehicle windshield, for example, in which case it can be easily inserted to close a windshield bay surrounded by a windshield. a frame of appropriate shape to cooperate with the joint of the assembly. Initially, vehicle windshield assemblies were made up of several elements including sealing adhesives applied to the marginal edges of the glass sheet around the latter, suitable fastening metal members such as metal clips, and outer decorative rods arranged to cover the junction between the marginal edges of the glass sheet and the adjacent portion of the body

of the vehicle.

  These structures were therefore obviously expensive

in matter and manpower.

  Next, in an effort to improve the structure, self-contained window assemblies of the type described in U.S. Patent No. 4,072,340 are disclosed. adjacent frame and a molded envelope or seal, such as polyvinyl chloride, extending between the frame and the peripheral edge of the window to hold the glass sheet and the frame together. spaced points along the frame so that the assembly can be guided in one block to its position above the bay of a vehicle body,

  the fasteners passing through aligned openings in the vehicle body and being secured to the interior of the vehicle.

the vehicle.

  Other window assemblies, such as that described in U.S. Patent No. 4,139,234, include a gasket or molded gasket surrounding the edge of the glass panel, the fasteners being molded into the trim or seal and protruding

  be connected to an associated vehicle body.

  The relatively heavy frames of the above-mentioned assemblies, these frames being generally molded of zinc or other metals or alloys, and / or the seal, the liner or the molded envelope for fixing the frame to the window, In addition, as described in the aforementioned U.S. Patent No. 4,072,340, the outer decorative frame, which requires securing means spaced along its length for securing the entire assembly to a vehicle , requires expensive techniques, using a frame or a joint, which makes

  expensive and long frames to install.

  In an attempt to reduce the overall height of a window assembly of the type described above and to reduce the cost thereof, other window assemblies of the types described in United States Patent No. 3 have been designed. 759,004 and 4,364,595. The structure described in the first of these patents comprises a glass sheet surrounded, on board, with a trim strip, fixed in a suitable bay of a vehicle by means of a compressed adhesive between the glass and / or the trim strip and the adjacent part of the frame or frame surrounding the opening of the vehicle The trim ring is formed of a flexible plastic material having a groove in which the edge of the glass sheet is housed and a decorative front strip which protrudes from and is pivotable with respect to the edge of the front wall of the groove which extends on the inner side of the trim strip when it is fitted around the sheet of glass. gauze trimmer can be held in position on the glass sheet by suitable retaining clips

spring metal, for example.

-2553083

  The last of the aforementioned patents represents another window assembly which is installed so as to close a vehicle bay, for example, in one piece, advantageously from the outside. This assembly or assembly comprises a sheet of glass, one several types of decorative frames or elements hubcaps surrounding the glass sheet, and one or more fasteners directly attached to the glass sheet, but masks in sight The fixing means are advantageously metal studs rigidly and securely attached directly to the surface of the glass by means of a suitable adhesive The decorative frame can be injection molded as described in the aforementioned patent,

around the glass sheet.

  The invention relates to a relatively low weight and relatively low cost window assembly which can be assembled and

  installed in a vehicle at miniuaw handling costs.

  The invention relates to a window or glazing assembly or assembly as well as to its method of manufacture, in which the window material, generally a glass sheet, carries a synthetic resin mounting element or seal which surrounds the glass sheet. The peripheral element or seal is applied to the periphery of the glass sheet by injection into a mold cavity which surrounds the periphery of the glass sheet, with a composition capable of polymerizing and hardening in this region. cavity to form the joint; the composition establishes, by an autogenous mechanism resulting from its polymerization and hardening, inside the cavity of the closed mold, an intimate contact with the walls 30 forming the cavity of the mold and with the glass sheet is obtained from excellent results in realizing the mounting element in a polyurethane composition which hardens into a

microcellular elastomer.

  The process according to the invention subjects the glass or other transparent sheet material only at low pressures, differing in this respect from the processes according to which

  window assemblies with molded plastic frames

  have been produced so far, for example by injection molding in which a thermoplastic material, such as polyvinyl chloride or the like, is injected to be brought into contact with the surface of the material of the window under pressure. extremely high, generally in the range of 35 to 140 M Pa. In many cases, the desired preformed window assemblies comprise glass sheets having relatively small irregularities resulting from the manufacturing process. These irregularities are generally due to the fact that the surface of the glass is consists of areas in which the normally flat and flat configuration is interrupted by a series of small undulations defined by a series of close and rapid changes in the dimensions of the surface. In cases where this glass is used in the processes of

  injection molding, one can predict a considerable breakage.

  Therefore, the high injection pressures required by the injection molding processes require a substantially high pressure (clamping tonnage) to maintain the mold surface against the glass surface since the steel surfaces of the molds can not marry irregularities (and can not be designed to marry them because of the non-repetitive nature of these irregularities),

  these high pressures often break the glass, especially in areas with irregularities.

  The preferred resins according to the invention are polyurethanes, advantageously comprising linear or slightly branched propylene glycol polyethers and diphenylmethane diisocyanates (MDI) which are slightly modified either by a carbodimide or

  by reaction with glycols to give isocyanate compounds which are liquid at ambient temperature and of low viscosity to meet the work requirements of high pressure metering and blending equipment.

  Resins are formulated to be polymerized when injected into the mold cavity where polymerization and hardening occur Reactivity is adjusted to provide sufficient polymerization and cell stabilization, residence time in the mold Because of the relatively short time required for the production of the assembly in this respect, although room temperature cure is possible, the mold surfaces are generally maintained at temperatures of 60 to 70 ° C as laminated glass products.

can bear.

  The object of the invention is to produce a pre-formed window assembly or assembly comprising a glass sheet or other transparent material and a coating mold of a synthetic polymer type, such as polyurethane, which polymerizes to adhere in contact with one another. tight to the adjacent glass surface, allowing the entire preformed assembly to be installed to close a bay of

  vehicle or other, with minimal handling.

  Another object of the invention is to provide a preformed window assembly which can be installed to close an opening and attached without the need for auxiliary fasteners and trim strips. Another object of the invention is to produce a preformed window assembly in which the outer portion of a synthetic polymer molding molding includes an outer trim portion, designed for 4 m, the space between the surface of the exposed glass and the

  part of the vehicle or others, adjacent to the opening to be closed, to form a substantially flush mounting.

  The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting example and in which: Figure 1 is a rear view of the preformed window assembly according to the invention; Figure 2 is an enlarged perspective view of the assembly of Figure 1, with section along the line 2-2 of this figure; Figure 3 is an enlarged partial cross-sectional view of the peripheral edge portion of the window assembly of Figures 1 and 2 showing the application of a bead of adhesive prior to installation of the assembly; Figure 4 is a partial vertical section of the window assembly of Figures 1, 2 and 3 after it has been installed to close an opening; Fig. 5 is a schematic view showing the preferred method for manufacturing the preformed window assembly, shown in Figs. 1 to 4; Figure 6 is a more detailed schematic view showing the main elements involved in the implementation of the method illustrated in Figure 5; Figure 7 is a top view of a typical mold adapted to produce the preformed window assembly, shown in Figures 1 to 4; Figure 8 is an enlarged fragmentary sectional view of the mold structure of Figure 7 taken along line 8-8 of this Figure; Fig. 9 is an enlarged partial sectional view of the vacuum head portion of the mold assembly of Figs. 7 and 8 taken along the line 9-9 of Fig. 7; and Fig. 10 is an enlarged partial sectional view showing cooperating pads for supporting a glass article during the production of a window according to

  the invention by the method of Figure 5, this view also showing the cavities of the lower and upper parts of the mold.

  The invention relates to a glazing comprising a transparent sheet and a seal composed of a synthetic polymer bonded to predetermined parts of the sheet, characterized in that the seal has been polymerized on the spot in the immediate vicinity of said predetermined portions of the sheet and has established , by the autogenous mechanism resulting from

  its polymerization and its hardening, being maintained, a -contact intimate with the parts to which it is glued.

  In addition, according to the invention, there is provided a method of manufacturing an assembly of a transparent sheet and a seal adhered to the periphery of this sheet, the method being characterized by the steps of: ) positioning a transparent sheet within a mold cavity formed by a plurality of complementary mold parts, said cavity having the shape and position, relative to the transparent sheet, of the final seal and enclosing the marginal surfaces of the leaf in close proximity to its periphery; b) injecting into the mold cavity a composition which is capable of polymerizing and curing to produce a seal and which adheres to the marginal surfaces of the sheet once it has cured in contact with said surfaces; c) adjusting the pressure at which the composition is injected into the mold cavity at a sufficiently low level so that the sheet is not damaged; d) adjusting the temperature of the mold cavity, the injection of the composition and the amount of composition injected so that the composition polymerizes after its injection and that it establishes, by the autogenous pressure resulting from the polymerization, a contact intimate with the cavity of the mold and with the sheet, and harden while this contact is maintained; and

  e) removing the assembly from the mold cavity.

  Figures 1, 2, 3 and 4 show a preformed window assembly according to the invention and manufactured by the method of the invention. More particularly, there is shown a preformed rear window 10 intended to be inserted into a suitable opening of a body. This vehicle body has a rear wall portion 12 which generally defines the opening to be closed. The rear wall portion 12 is generally made of the stamped portion 8 and is suitably attached to a

  reinforcing element 14, for example by resistance welding.

  The rear wall portion 12 is generally made in one piece with a wall portion 16 projecting outwardly along its entire length and defining with the portion 12 a recess adapted to receive the preformed window assembly 10 The wall portion 16 results in a relatively sharp angle from which the material 18 is contoured and integrated with the trille defining the silhouette of the

associated vehicle.

  The preformed rear window assembly 10 comprises a suitably shaped window material, generally consisting of an optically transparent glass sheet. A synthetic resin mounting member or seal 22 surrounds the front, rear and rear sections. The outer bead or trim strip 24 of the gasket 22, as best seen in FIG. 4, covers a space between the peripheral edge of the glass and the metal of the body. of the vehicle surrounding the opening and ai is coestitué, eg Mle, of the wall part 16 when the preformed assembly 10

  is actually mounted on the vehicle.

  The portion of the element or mounting seal 22 that extends inwardly of the trim strip 24 surrounds the peripheral edge and the rear edge of the window 20 and terminates along its rear surface. A lip or a stop member 26 is located on the rear surface of the ice 20, some distance inward of the end of the mounting member or seal 22. The area between the end of the gasket 22 and the lip 26 is intended In addition, tabs 28 are formed in one piece with the gasket 22 with a suitable adhesive bead used for mounting the preformed window assembly.

  and the lip 26 and with a bridge 30 extending between the seal 22, on the one hand, and the lip 26 and the tabs 28, on the other hand.

  The tabs 28 constitute positioning and orientation means useful when mounting the assembly on an associated vehicle and to hold the assembly assembly in position until the associated adhesive has hardened to ensure the desired connection between the preformed assembly and

  the corresponding part of the vehicle.

  The first step in manufacturing the rear window 10 is to completely clean the front, rear and peripheral edges of the glass sheet 20 to pre-pare the surfaces to adhere to the mounting gasket 22, the lip 26 and the associated tabs 28. It has been found desirable in some cases to apply a layer 32 of opaque paint, a glass frit glaze or the like to a portion of the back surface of the foil 20. The opaque material of the diaper 32 is generally used in

  where it is necessary to mask ice-mounting materials and structures from the outside as well as, for example, wiper drive mechanisms and, in some cases, where it is useful to protect them ultraviolet rays.

  The next step in the manufacture of the rear window 10 is to apply a primer coat to previously cleaned glass surfaces. Satisfactory results have been obtained by the initial use of a layer 34 of a product marketed under the name "Betaseal, Glass Primer 435 18 Commercial Grade", by Essex Chemical Corporation, Clifton, New Jersey, US A. The bonding zone on the glass is initially coated with the primer to form the layer 34 which assumes the The material is a clear, moisture-sensitive primer comprising a gammaaminopropyltriethoxysilane which promotes adhesion between "Betaseal" type products.

and the glass.

  After the application of layer 34, a second primer layer 36 is applied to this layer 34. Satisfactory results are obtained when using a product marketed under the designation "Betaseal, Glass Primer 435 Commercial Grade", Essex Chemical Corporation This material is a protective primer which prevents the ultraviolet degradation of urethane adhesives and sealants and assists in the rapid formation of a hydrolytically stable bond between glass and glass. urethane Approximately 20 minutes after the application of the superposed layers 34 and 36, the assembly is placed in the cavities of a mold where the seal 22, the lip 26 and the tabs 28 of polyurethane are produced; the mold is part of an apparatus which will be described in greater detail hereinafter with reference to FIGS. 5 to 10 It is often desirable to apply a coating 38 to the exposed outer surface of the trim portion of the gasket 22 prior to laying The coating 38 may be a black urethane paint, such as that produced by PPG Industries, Inc., Pittsburgh, Pennsylvania, US A, under the designation "Purethane 700 HSE-848". The coating 38 is then fired at about 60-66 ° C for about 20 to 30 minutes. The coating 38 is applied to protect the exposed polyurethane seal from damage that would otherwise result from exposure to ultraviolet radiation, normally present. in the light

unfiltered sun.

  The preformed window assembly may be installed in a suitable vehicle bay by the application of a bead 40 of adhesive, for example a urethane mastic such as the mastic produced by Essex Chemical Corporation under the designation "Betaseal 551 2", with water paste, on the marginal surface of the trailing edge, between the seal 22 and the spaced lip 26, the assembly then being aligned with the vehicle bay and pushed into position When the assembly or assembly is aligned with the vehicle bay, the lugs 28 are aligned on spaced complementary openings 42 formed in the portion 12 of the rear wall and in the associated element 14 of the vehicle reinforcement. Tabs 28 have tapered noses facilitating alignment. When the assembly is pushed into position, the tapered or tapered noses of tabs 28 pass through apertures 42 and resiliently engage with positions 42. e locking in which they maintain the

  adhesive bead 40 in a compressed state (see FIG. 4).

  As soon as the adhesive 40 hardens, the installation is finished.

  Referring now to Figures 5 to 10, the apparatus for manufacturing assembly or assembly 10 includes a primer application station 50 and a molding station 52 (see Figure 5) which includes a storage zone 54 in bulk of which a stream, formed of a mixture of a polyol, a chain extender, for example, ethylene glycol, a pigment and a catalyst, and a separate stream constituted An isocyanate is supplied, as required, to a urethane dosing station 56. The isocyanate from the bulk storage tank 54 is directed to a conditioning tank 58 while the polyol mixture is directed to a tank 60. The outlets of tanks 58 and 60 communicate with volumetric cylinders or metering pumps 66 and 68 at high pressure through respective recycling pumps 62 and 64 to constantly keep the circulating material in the supply lines.

  ending in a mixed head Se 74 and in recycling lines returning to the volumetric cylinders 66 and 68.

  Heat exchangers 70 and 72 are used in the cured circuit to maintain desired reaction body temperatures. Constant movement and temperature control are essential to maintain the various insoluble compounds in suspension at temperatures at which the reactants remain inert and liquid. but to which they react quickly when brought into contact. An injection device is provided for injecting a charge composed of closely fitting portions of the two circulating streams into the mold at a constant and steady flow. Metered feeds of both streams are supplied to the mixing head 74. from the outputs of the volumetric cylinders 66 and 68, respectively, under the action of the pistons which are shown schematically The injection into the mixing head 74 is effected under the application of a pressure in the range of about The two streams are intimately mixed in the mixing head 74 The mixture passes from this head into an associated mold 76 at a pressure of about 350 to 700 k Pa The mold is generally maintained at

  a temperature between 60 and 66 C.

  The mold 76 comprises a lower portion 78 (FIG. 7) and an upper portion 80. Suitable means (not shown) are for opening and closing the mold parts 78 and 80. When the mold parts are open, the glass sheet 20 is positioned on the lower part 78 so that the parts of the rear surface 10 of the glass rest on pads 82 placed in appropriate positions After the glass piece 20 has been properly positioned on the pads 82 of the lower part 78 of the mold the upper portion is lowered to a position in which the outer peripheral edges of the complementary portions 78 and 80 can be clamped against each other in metal-to-metal contact externally to the mold cavity. 80 of the mold carries studs 84 which cooperate with the pads 82 to elastically press against the glass sheet 20 and retain it 20 inside the cav mold cavity Mold cavity 76

  is larger than the glass sheet 20 formed to prevent any contact between the glass and the metal.

  The upper portion 80 of the mold 76 comprises vacuum heads, shown in FIGS. 7 and 9, for raising the glass with the portion 80 of the mold when the molding operation is complete and it is desired to remove the sheet of mold 20 of the mold 76 The vacuum head mainly comprises a suction cup 86 which communicates

  with a source of vacuum by a pipe 88.

  A number of movable mold segments, indicated generally at 90, are provided at spaced points on the circumference of the mold, these points corresponding to the positions of the tabs 28.

  identical and can slide in corresponding recesses 92 provided in the lower portion 78 of the mold.

  The outer end of each segment 90, with respect to the mold, is xfie to a block 94 which is functionally connected

2553 081

  at the distal end of a piston rod 96 an Kee of a

  reciprocating motion in a conventional cylinder 98 to fluid.

  The opposite end or inner end of each segment 90 ends with a profile corresponding to the outer profile of the seal 22 and has an extension 100 which forms the notch in the lug 28 In operation, the piston rod 96 performs an extension movement advancing the mold segment (Figures 8 and 10) so that it is ready to receive the charge of the resin forming the seal After polymerization and hardening of the seal material, the piston rod 96 and the movable segment 90 of the The molds are retracted, as shown in phantom in FIG. 10, which has the effect of removing the extension 100 from the notched portion of the tab 28, and releasing this tab, as well as the rear window assembly, so that it can be removed from the lower element 78 of the mold when the upper element 80 of the mold

is relieved by depression.

  After the assembly has been discharged from the mold portion 78, any excess seal material or any burr is removed at a station 101, the assembly is washed and dried in a station 110 and the paint layer 38 is applied to the exposed outer trim part of the seal 22

  and it is fired to harden in station 120.

  The following example is the best mode of operation currently planned. It is given as an illustration

and not limiting.

EXAMPLE

  The surfaces of the upper and lower mold parts, which surround the mold cavity formed between these two parts, when they are assembled, are treated with a solvent-based mold release agent which is a mixture of waxes; the particular release agent is marketed by the company Park Chemical Company, Detroit, Michigan, USA, under the designation "PRC35 789". A glass sheet 20 is then appropriately placed on the lower element 78 of the mold, after which the upper element 80 is assembled on the lower element

  78 and the two elements are tight against each other.

  A filler composed of one part by weight of a polyol composition and 0.63 part by weight of an isocyanate is then forced into the mixing head 74, under a pressure of 17.5 M Pa, and then into the mold 76 at a pressure of about 350 k Pa The polyol and isocyanate streams are at a temperature of 43 C, while the mold 76 is at a temperature of 62 C The currents of polyoi and isocyanate are intimately mixed in the head 74 before reaching the mold 76 About a minute and a half after injecting the urethane composition into the mold 76,

  the latter is open and the assembly 10 is removed.

  The resulting elastomeric seal 22 has a microcellular structure, a density of 1.07 g / cc hardness (Shore "A") of 90, a tensile strength of 10.5 M Pa, an elongation ratio at the break of 279% and

  a flexural modulus (at 24 C) of approximately 24.5 M Pa.

  The composition of the polyol used in the process described in the above example consists of 45.4 kg of a base polyol, namely a polyether triol with a molecular weight of 600, with a "termination" of ethylene oxide, sold under the trade name "Voranol 5815" by Dow Chemical Company of Midland, Michigan, USA, 4.54 kg ethylene glycol and 1.36 kg polyol 20% black 25 carbon The isocyanate used in carrying out the process of the above example is modified 4,4'-diphenylmethanediisocyanate, sold under the trademark "Rubinate LF 179" by Rubicon Chemicals Inc., Geismar, Louisiana, US A. The above components are catalyzed by the addition of dibutyltin dilaurate and a solution of

  triethylenediamine in dipropylene glycol.

  It goes without saying that many modifications can be made to the glazing described and shown without departing from the scope of the invention. For example, although the preformed window assembly 10 is a rear window structure for an automobile, it is necessary to note that an assembly according to the invention can be used both for any fixed glazing for vehicles such as

  automobiles, trucks, vans or cars, as well as many other applications including architecture, appliances and the navy.

  The configurations of the trim part 24 and the molding 22 are suitable for accomplishing aerodynamic objectives of the automotive industry A new goal of automotive industry researchers is to create more aerodynamic vehicle configurations to increase vehicle performance and thus reduce the power required to allow for lower fuel consumption Since the rear window and the windshield are obvious sources of considerable resistance to airflow, constant attention has been paid to aerodynamic improvement of the configuration of the rear window and windscreen assemblies and means of attachment and

  decorative chopsticks used with them.

  It should be noted, considering the windshield structures of the type currently known, as previously described, that the various fastening means and the various rods are imperfect from the aerodynamic point of view and generate undesirable turbulence which detracts from the efficiency The invention provides a pre-formed windshield assembly which can be integrated into a flush mounting system in which the trim strip, corresponding to the outer surface of the vehicle and which also generates unpleasant wind noise within the circulating vehicle. part 24 of the element or seal 22 mounting, substantially flush adjacent surfaces, thus significantly improving the aerodynamic characteristics and reducing unwanted turbulence and wind noise resulting. Although the preferred form of the invention uses a polyurethane composition to achieve the desired results, other compositions of "Nylons", polyesters

  and epoxides can be suitably used.

16 i:

Claims (15)

  Glazing comprising a transparent sheet (20) and a seal (22) composed of a synthetic polymer bonded to predetermined portions of the sheet, characterized in that the seal has been polymerized in situ, in close proximity to said predetermined portions of the sheet. sheet, and established, by the autogenous mechanism resulting from its polymerization and hardening, at the same time that it is maintained, a   intimate contact with the parts to which it is glued.   2 glazing according to claim 1, characterized in that the seal comprises a trim portion (24) projecting outwardly of the sheet, in a plane substantially parallel to the adjacent marginal front surface of said sheet.   3 pane according to one of claims 1 or 2,   characterized in that the sheet is glass.   4 Glazing according to any one of claims 1 to 3, characterized in that the sheet is glass   laminated glass 5 according to claim 3, characterized   in that the glass sheet is quenched.   Glazing according to one of Claims 1 to 5, characterized in that the gasket is disposed over the entire periphery of the sheet and is bonded to the adjacent marginal surfaces of the edges of the sheet.   Glazing according to any one of claims 1 to 6, characterized in that the seal is composed of a   polyurethane. 8 Glazing according to any one of revendica30 tions 1 to 7, characterized in that the seal is composed of a   microcellular polyurethane elastomer.   9 glazing according to any one of claims 1 to 8, characterized in that the apparent surface of the   seal is coated with a layer (38) absorbing ultraviolet rays.   Glazing pane according to one of Claims 1 to 9, characterized in that the gasket has a   a generally U-shaped section opening towards the outside of   the surface of the back edge of the sheet.   11 Glazing according to claim 10, characterized in that the groove is defined by two spaced ribs (26) forming between them a zone intended to receive a adhesive (40).   12 Process for manufacturing an assembly of a transparent sheet and a seal bonded to the periphery of the sheet, characterized in that it consists in: a) positioning a transparent sheet (20) inside a mold cavity, formed of a plurality of complementary mold parts, the cavity having the shape and position, with respect to the transparent sheet, of the final seal and enclosing the marginal surfaces of the sheet in close proximity to its periphery; b) injecting into the mold cavity a composition which is capable of polymerizing and curing to produce a seal and which adheres to the marginal surfaces of the sheet as it has cured in contact with these surfaces; c) adjusting the pressure at which the composition is injected into the mold cavity, a value sufficiently low that the sheet is not damaged; d) controlling the temperature of the mold cavity, the injection of the composition and the amount of injection composition so that the composition polymerizes after its injection and establish, by the autogenous pressure resulting from the polymerization, an intimate contact with the cavity of the mold and with the sheet, and harden during this contact;   and e) removing the assembly from the mold cavity.   Method according to claim 12, characterized in that a primer is applied to the marginal surfaces of the sheet, before the material is placed in the mold cavity, the finish having the effect of improving the adhesion of the joint on marginal surfaces   Process according to one of Claims 12 and 13,   characterized in that the sealant composition comprises an isocyanate and a polyol and, after polymerization and hardening,   form a microcellular polyurethane elastomer.   Process according to claim 14, characterized in that the mold parts surrounding the mold cavity are maintained at a temperature between about 60 and 70 ° C.   Method according to one of claims 14 and   characterized in that the composition is injected into   the mold cavity at a pressure of about 350 to 700 kPa.   Process according to any one of Claims 12 to 16, characterized in that the material of the sheet is laminated glass.   Process according to one of Claims 12 to 16, characterized in that the material of the sheet is tempered glass.   Method according to any one of claims 12 to 18, characterized in that it consists in applying an ultraviolet absorbing coating on the apparent surface of the joint after it has been removed from the cavity of the mold.