MXPA96002267A - Method to manufacture lamina confined windows - Google Patents

Abstract

This invention is directed to a method for manufacturing shaped, laminated window panes comprising an inner glass sheet, and an intermediate layer such as thermoplastic material and an outer glass sheet. The method comprises providing a layer of a water-based silicate paint on at least a portion of the surface of the glass sheet to be supported against the intermediate layer, drying the paint at a moderate temperature and removing the water and cure the paint, place the glass sheets together so that the surfaces that are leaning against the intermediate layer are in close proximity to one another and in parallel, bending the glass sheets simultaneously towards a final configuration at a high temperature and cool the glass sheets

Description

"METHOD FOR MANUFACTURING LAMINATED CONFINED WINDOWS" FIELD OF THE INVENTION This invention is directed to a method for manufacturing laminated shaped windowpanes comprising an intermediate layer, such as a thermoplastic film, laminated between two configured glass sheets. More particularly, at least one of the sheets is provided with a water-based silicate paint on a surface to be supported against the intermediate layer.

BACKGROUND OF THE INVENTION Laminated glass windows of vehicles Jn > automotive, e.g., windshields, often include an opaque edge around the peripheral marginal surface 20 of the windows. This obstruction band hides from the external view, the adhesive or any other securing means that remains behind the periphery of the windshield. These edges are generally ceramic enamel compositions formed from a mixture of metal u ^ wKA metal oxides and glass frit in an appropriate organic vehicle. In some situations, these edges are carried on the surface of the glass that is. exposes inside the vehicle when the windshield has been provided in the vehicle. The paint that has been applied on the non-folded glass is baked to that surface when the glass passes again from the bending bend furnace as one of a pair of _. glass sheets that bend bending together before the * < 10 lamination. It has been more desirable, from a durability point of view, to provide these edges on a surface of the sheet of glass that rests against the interlayer in the laminate. In the Patent North American Issue 4,644,139 given to Harrison et al., A process to provide this edge is disclosed. Involves the bending bend of the two sheets of glass together with the possible internal surface of the other glass sheet that carries the opaque band that remains above during the fold. After allowing the glass sheets to cool, a plastic interlayer is placed over the inner glass sheet and then the outer sheet is placed in the interlayer with the opaque band contacting the interlayer. Finally, the sheets of glass come together in the interlayer. One disadvantage of this invention is that as the curvature of the shaped glass increases, it has less chance that, after changing the glass sheets, it coincides to form an appropriate composite windshield. Another conventional process 5 for making a laminated windshield with a ceramic paint border as disclosed in U.S. Patent No. 4,786,784 issued to Nikodem et al. Involves two baking steps, one to melt the paint and melt it to the surface of the paint. glass and the second , 10 to configure the glass templates. These processes, because they require two baking of the glass, increase the possibility that the glass has optical distortions. Typically in this process, a ceramic paint is applied to one of the windshield stencils and then dried to remove the organic constituents and baked to melt the paint on the stencil, with the stencil in a "flat" condition. After applying a separating agent in the paint, this template is placed in pairs with another windshield template, the painted surface 20 placed within the pair of stencils and the pair is baked and folded to the desired final configuration. After cooling the templates, they are separated and then the separation agent is removed by washing and finally an interlayer such as polyvinyl butyral is laminated between the pair of templates. In this process there is an increased risk that by melting the paint during the bending of the glass, the glass sheets will stick together. As will be appreciated, the painting baking and the bending of the glass until its final configuration has not been carried out in one step because the paint contains organic constituents that form gaseous reaction products at the baking temperature. The gases can not escape from the space between the two glass templates during the bending of the glass. UNCLE The American Patent Number 5, 324,373 issued to Gillner et al., Discloses an improved process for manufacturing this windshield. It involves painting one of the windshield stencils and then after drying the paint, place the templates in pairs with the side painted outwards. Subsequently, the pair is baked to pre-bend the pair to a partial configuration and bake the paint. The paint is then coated with a separating agent and the pair of templates is reassembled with the side painted inward. The 20 couple that has been reassembled is reloaded into a fold attachment and then re-baked to complete the setup process. The cooled pair is then washed from the separation agent and laminated with an interlayer therebetween. This process is elaborated and again requires a double baking of the glass with the increased possibility of optical distortion. The method of the present invention involves overcoming the deficiencies of the processes of the prior art described above.

This invention is a method for manufacturing a window pane configured of laminated glass, the laminated glass comprising an inner glass sheet, an intermediate layer and an external glass sheet. The method comprises the steps of: providing a layer of water-based silicate paint on at least a portion of the surface of the glass sheet to be supported against the intermediate layer; drying the paint at a temperature lower than the softening temperature of the glass, to essentially remove the water present in the paint and cure the paint; placing the outer and inner glass sheets 20 together so that the surfaces of the glass sheet that are to be supported against the intermediate layer are in proximity with one another and are parallel; folding the outer and inner sheets simultaneously towards a final configuration at an elevated temperature of at least about 550 ° C; and cool the outer and inner glass sheets. Advantageously, in accordance with the method of this invention, the glass windows configured laminates with internal surfaces printed with paint eg, an edge of opaque paint, can be produced simply such as for automobile windshields. The method of the invention allows the manufacture of these . windows with less distortion and in a more ^ 10 simple and efficient than the processes of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a glass template having an opaque paint placed thereon. Figure 2 is a schematic representation in an end view of two glass stencils 20 assembled one above the other before an operation to bend the glass. Figure 3 is a schematic representation of the two glass templates of Figure 2, after the folding operation has been completed. and DETAILED DESCRIPTION OF THE PREFERRED MODALITIES As disclosed in the foregoing, the manufacturing method of the present invention is used to provide a window pane configured of laminated glass such as a car windshield or rear tail light. This laminated glass comprises an inner glass sheet, an intermediate layer such as a plastic material, for example, polyvinyl butyral and djkt or an outer glass sheet. The laminated glass carries, in at least a portion of a surface of the glass sheet to be supported against the intermediate layer, a layer of a water-based silicate paint. Preferably, this painting would be an opaque paint and would provide as an edge around the entire perimeter of the glass sheet. The object of the opaque area is to avoid being able to see from the outside of the vehicle such locations as under the dashboard or above the upper pole such as areas that are otherwise visible due to the location and way to install a windshield in a vehicle. Most modern vehicles have the same opaque areas. These areas can be located individually, for example, on the top and bottom of a windshield or on the sides thereof. "" ^ fe * The paint used in this method is a water-based silicate paint. The preferred water-based paint of this method includes soluble silicates eg, sodium or potassium silicates, as the main ingredient, metal oxides, for example, copper oxide as the dye in that case providing a black color to paint and water. A number of water-based silicate paints of this type can be obtained commercially being one of them CERAM-VUE ™ (Industrial Control 'r lO Development, Inc., of Vancouver, WA), which is a black water-based silicate paint. of this type. Still other water-based silicate paints useful in this method of the invention will be apparent to those skilled in the art in view of this disclosure. A The water-based silicate paint used in a particularly preferred manner in the present method is disclosed in the US Patent Application Number of i ^ Series filed on, 1995 and named "Water-Based Paint for Glass Sheets" granted to Boaz, the Which has been commonly assigned with this invention. It comprises sodium silicates, water, finely divided metal oxide pigment and zinc oxide as an adhesion promoter. In accordance with the statement of this In the invention, the following is presented as a description of a preferred embodiment of the method for producing a laminated window pane configured such as a windshield, having two glass sheets with an interlayer therebetween and a paint carried on the at least a portion of the glass sheets that will be supported by the interlayer.

While the paint can be carried on a portion of one of the glass sheets, if desired it can be carried on both sheets of glass, which will rest against the ^ interlayer. The description is not intended to be a limitation to the broader principles of this method and even when preferred materials are used to illustrate the method of the present invention, it does not mean that other materials can not be used in the method. A glass template 10 of a glass sheet as shown in Figure 1, is provided with a layer of water-based silicate paint 12 around the peripheral portion. This template glass (or glass sheet) 10 is the template that will be facing the outside of the automotive vehicle when installed in the vehicle. In general, this external glass template is larger than the glass template that will face the interior of the vehicle (the internal glass template) when the outer and inner glass templates are laminated together using a lamination interlayer. The paint 12 is provided, in accordance with one embodiment, on the surface of the first glass stencil 10 which will come into contact with the interlayer when the glass stencil 10 is laminated to another glass stencil to form a glass stencil 10. laminated windshield. In the art, the surfaces of the template 10 are commonly designated surface # 1 and surface # 2. Surface # 1 is that which will be most outwardly when the windshield is installed in the vehicle and surface # 2 is that that is put in tf lO contyacto with the interlayer. While the paint may be provided on the outer surface # 2 of the outer glass stencil as described above, it may alternatively be provided or provided also on the inner glass stencil on that surface (# 3) that comes in contact with the interlayer on the assembled windshield. It is preferred that the template be provided on the surface # 3. The paint can be applied by any technique, such as lamination, by brush or stencil printing, preferring this last technique. In order to optimally apply the paint, a moist environment is preferably maintained around the paint. This environment can be maintained e.g., by means of the invention disclosed in the North American Application Serial No. 08 / 295,574 Bp filed on August 25, 1994 and designated "Apparatus and Method for Applying to Coating to Glass" whose invention has been commonly assigned with this invention. In several of the examples of the method of the present invention, wherein the water-based silicate paint employed falls within the invention disclosed above as having commonly yielded, the moisture surrounding the paint that is being preferably applying a relative humidity of 80 + 5 percent RH at av. However, it is not necessary to maintain a humid environment in order to carry out the method of this invention. The selection of the optimum environment would be within the skill of a person of the art in view of the present exposure. 15 The paint is then subjected to elevated temperatures by means of an infrared (IR) oven or a microwave oven to expel essentially all the water in the paint and cure the paint. This step is carried out at a temperature lower than the temperature of softening of the glass, the specific temperature not being critical. Preferably a moderate temperature e.g., a lower one of about 400 ° C, more preferably between about 100 ° and 200 ° C is used. Since water is the only volatile component When it is to be expelled after which the paint forms an itpt cured film, moderate temperatures lower than the softening temperature of the glass can be employed.

This is in contrast to the methods that employ providing paints for vehicle-based glass organic that require a much higher temperature, that is, above the softening temperature of the glass, for its cure. In one embodiment, when the paint disclosed in the foregoing is applied to the template in a thickness of At about 15 microns, the drying of the paint in an infrared oven was achieved in about 1 minute at a temperature of about 93 ° C, whereas correspondingly less than about 1 minute was required in a microwave oven. In what relates to the time required to dry and cure the paint layer, the thickness of the paint layer is not critical. The optimal parameters for drying and curing the paint layer # will be evident to those skilled in the art in view of the present exposure. After the step of drying, the paint is bonded to the selected surface of the glass stencil so that it can not be scraped off the glass if it is attached by a tool or other scraping element. The bond is sufficiently strong so that the glass template can be handled and moved from one operation to another without damaging the painted opaque areas. Reference will now be made to Figure 2. Then, in accordance with the present method, a second glass template 14 (which has the surfaces # 3 and # 4) and the first glass template 10, which are shown only in an end view of Figure 2 and Figure 3, so that the surfaces of the glass template (# 2 and # 3) that they are to be supported against the intermediate layer, they remain in proximity to each other and in parallel. The second glass stencil 14 is usually shorter than the first glass insole 10. The second glass stencil 14 will be oriented within the automotive vehicle when the windshield is installed in the vehicle. More particularly, the surface # 4 of the internal template of the installed windshield will be more • ^ inside the vehicle interior. Subsequently, 'the external and internal templates are doubled simultaneously towards a final configuration at a high temperature of at least about 550 ° C, e.g., or any of the processes available for bending glass. Preferably, the temperature for bending the glass is between about 550 ° C and 650 ° C. A commonly used process involves an accessory 18 for bending glass of the Figures 2 and 3. In this process, the bending of the pair of templates of ^ ^ and ^ glass can be carried out by placing the pair 10, 14 in the fixture of 16 bending, as shown in Figures 2 and 3. accessory that carries the pair of templates then it would be placed in an identified glass bending chamber generally by the number 18. As is well known in the art, this bending chamber is an elongated chamber through which the device for bending glass moves slowly. As the bending device moves through the camera, the templates 10, 14 of ^ \ L0 glass are heated to a high temperature which causes them to bend or warp in accordance with the configuration surface or the glass bending device as shown in Figure 3. In this way the glass sheets are folded to the configuration- appropriate for form a laminated windshield. Their relative position with respect to each other in Figures 2 and 3 is the same as in the ^ * manufactured windshield. After the first and second glass templates have been bent as shown in Figure 20 3, they are cooled and separated from one another. During the bending operation, the opaque area 12 is bonded to the glass surface to form an even more permanent part of the glass surface. The glass templates can also be provided with an electroconductive coating if the window will electrically heat the windshield or the heating grilles as used in the rear or rear lights and connection clips and so on. More specifically, these windows may include printed and baked heating conductors and an electrically conductive multilayer system applied to the surface of the outer glass sheet that abuts against the intermediate layer. In this situation, after the cooling step, the sheets would be separated and then an electrically conductive multilayer system would be applied to the surface of the glass sheet that rests against the intermediate layer. In order to form the laminated windshield, an interlayer (not illustrated in the Figures) is interposed between the folded glass templates 10, 14. The normal lamination interlayer used is polyvinyl butyral which is well known in the art. Then, the glass templates are laminated in a normal well-known lamination operation to form a laminated glass windshield. The following example is presented as a description of the method of the invention and for disclosing a preferred embodiment proposed by the inventors, but should not be construed as limiting.

* EXAMPLES This is an example of conformance to one embodiment of the method of the present invention. As disclosed above, in the windshield manufacturing branch, the surfaces of two stencils used to produce a windshield have been fine-tuned with # 1 to # 4 for their surfaces, advancing from # 1 to the outside of the vehicle to # 4 inside the vehicle. Long and short templates are cut from the flat glass sheets. A black silicate paint (sodium silicate, copper oxide pigment, water and zinc oxide) is printed by stenciling on the short templates on the # 3 surface around the periphery. The paint is dried at a temperature of about 100 ° C using a microwave oven. The microwave does not heat the glass. The long and short templates are matched and assembled so that the paint is inside the pair. The torque is loaded into the bending fixture and passed through an oven and heated to a temperature of about 575 ° C to double the torque to the desired configuration. After the pair is cooled, the templates are separated, washed and dried. A layer of polyvinyl butyral is provided between the two templates (surfaces # 2 and # 3) and the pair with the interlayer is autoclaved at an elevated temperature of approximately 150 ° C and pressure of approximately 19.35 kilograms per square centimeter to bind the vinyl to the surfaces and form the laminated windshield.

Claims (9)

- lí CLAIMS

1. A method for manufacturing a window pane configured of laminated glass, the laminated glass comprises an inner glass sheet, an intermediate layer and an outer glass sheet, the method comprising the steps of: providing a layer of a silicate based paint of water in at least a portion of the surface of the sheet of glass to be supported against the intermediate layer; drying the paint at a temperature lower than the softening temperature of the glass to essentially remove the water present in the paint and curing the paint; placing the outer and inner glass sheets together so that the surfaces of the glass sheet that are to be supported against the intermediate layer are in proximity with one another and are in parallel; 20 folding the outer and inner sheets simultaneously towards a final configuration at an elevated temperature of at least about 550 ° C; and cool the outer and inner glass sheets.

Sk ^ '. The method according to claim 1, wherein the step of bending is carried out using an accessory for bending glass.

3. The method according to claim 2, wherein the accessory for bending glass has a bending surface that coresponds to the final configuration of the surface of the outer glass sheet.

4. The method of compliance with the Ét ^^ L? claim 1, wherein the window pane is an automotive window and the intermediate layer is a thermoplastic film.

5. The method according to claim 4, wherein the thermoplastic film is polyvinyl butyral.

6. The method according to claim 1, further comprising the step of laminating an interlayer between the inner and outer glass sheets to form the window pane.

7. The method according to claim 1, wherein the window is an automotive windshield and / or an automotive rear or rear window.

8. An automotive window that is produced in accordance with the method of claim 1.

9. A method for producing an automotive window pane configured of laminated glass having an inner glass sheet and an outer glass sheet, and an interlayer of thermoplastic film, the method comprising 5 steps of: providing a layer of water-based silicate paint on at least a portion of the surface of the glass sheet to be supported against the intermediate layer; 7i0 dry the paint at a temperature of less than about 400 ° C to essentially remove the water present in the paint and cure the paint; placing the outer and inner glass sheets together so that the surfaces of the glass sheet 15 that are to be supported against the intermediate layer are in proximity with each other and remain in parallel; folding the outer and inner sheets simultaneously towards a final configuration at an elevated temperature of at least about 20 550 ° C; and cool the outer and inner glass sheets. The method according to claim 9, wherein the bending step is carried out using an accessory for bending glass. A 11. The method according to claim 10, wherein the accessory for bending glass has a bending surface that corresponds to the final configuration of the surface of the glass sheet 5 external. 12. The method according to claim 11, wherein the thermoplastic film is polyvinyl butyral. 13. The method of compliance with the 10 claim 11, wherein the step of drying involves subjecting the paint to an infrared oven or a microwave oven. *