This application claims priority to U.S. Provisional Application No. 63/090418 filed on October 12, 2020, entitled “Method of Preparing a Substrate”, and U.S. Provisional Application No. 63/090452 filed on October 12, 2020, entitled “Method of Preparing a Substrate” the entire contents of which are incorporated by reference herein in their entirety.

Technical Field

The present disclosure generally relates to a method of preparing a substrate having a film thereon, a method of preparing a laminated glazing including such a substrate, and a mold for the methods.

Background

Laminated glazings may be used for various purposes, including automotive applications. Laminated glazings known in the art may include a film laminated there, such as functional film. Functional films may, for example, be used to provide a printed pattern, heat control, or head-up display (HUD). In some glazings, a laminated film may include a switchable function, such as a polymer dispersed liquid crystal (PDLC) film. Where a film is laminated, multiple adhesive layers may be used around the film between glass substrates. Production of multiple layers may lead to air between the layers which may negatively affect a final laminated glazing. It is thus desirable to provide laminated glazings, including those with a laminated film, which do not have air within the glazing.

Summary of the Disclosure

Disclosed herein is a method of adhering a film, including: providing a functional film on a first glass sheet wherein the functional film includes an adhesive layer on a major surface of

SUBSTITUTE SHEET (RULE 26) the functional film, wherein the adhesive layer is positioned between the functional film and the first glass sheet; applying a mold over the functional film to provide an assembly; adhering the functional film to the first glass sheet; and removing the mold.

The method may further include placing an interlayer and a second glass sheet over the functional film after removing the mold to provide a lamination stack, deairing the lamination stack, and autoclaving the lamination stack to provide a laminated glazing. The mold may include the second glass sheet. The laminated glazing may be a windshield.

In an embodiment of the present disclosure, adhering the functional film to the first glass sheet may include heating the assembly. Heating the assembly may include heating the assembly to a temperature from 85°C to 200°C. Heating the assembly may include heating the assembly to a temperature from 90°C to 150°C.

In another embodiment, the method may further include applying pressure to the assembly. Adhering the functional film to the first glass sheet may include heating the assembly. Heating the assembly may include heating the assembly to a temperature from 85°C to 120°C. Heating the assembly may include heating the assembly to a temperature from 90°C to 110°C. Applying pressure to the assembly may include applying a vacuum to the assembly. The pressure on the assembly may be from 0.85 to 1.10 bar.

In another embodiment, adhering the functional film to the first glass sheet may include irradiating the assembly with ultraviolet light, infrared light, or visible light.

In another embodiment, an outer surface of the mold facing the functional film may be non-adhesive. In another embodiment, the mold may include an outer mold and a support attached to the outer mold. The support may have a shape matching that of the first glass sheet. The first glass sheet may have a curved shape, and the support may fit to a convex surface of the first glass sheet.

In another embodiment, the outer mold may include a fluoropolymer layer. The fluoropolymer layer may include polytetrafluoroethylene.

In another embodiment, the mold may include a liner and a cushion material. The cushion material may include a fluoropolymer elastomer. The cushion material may include an interlayer material including a polymer adhesive. The polymer adhesive may include polyvinyl butyral. The liner may include fluoropolymer. The fluoropolymer may include polytetrafluoroethylene.

In another embodiment, the functional film may include a head-up display film. The functional film may include a base film that includes polyethylene terephthalate. The functional film may include a base film that includes cellulose triacetate. An entire of a major surface of the first glass sheet may be covered with the functional film.

In another aspect of the present disclosure, a mold for the above methods may include a liner, a cushion material and a support attached to the cushion material.

In an embodiment of the present disclosure, the cushion material may include a fluoropolymer elastomer. The cushion material may include an interlayer material including a polymer adhesive. The polymer adhesive may include polyvinyl butyral. The liner may include fluoropolymer. The fluoropolymer may include polytetrafluoroethylene. An outer surface of the liner may be non-adhesive. Brief Description of the Drawings

The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more example aspects of the present disclosure and, together with the detailed description, serves to explain their principles and implementations.

FIG. 1 illustrates a first glass sheet and a functional film, according to an exemplary embodiment of the present disclosure.

FIG. 2 illustrates an assembly, according to an exemplary embodiment of the present disclosure.

FIG. 3 illustrates an assembly, according to an exemplary embodiment of the present disclosure.

FIG. 4 illustrates an assembly, according to an exemplary embodiment of the present disclosure.

FIG. 5 illustrates the first glass sheet having the functional film thereon, according to an exemplary embodiment of the present disclosure.

FIG. 6 illustrates a laminated glazing, according to an exemplary embodiment of the present disclosure.

Detailed Description

Disclosed herein are exemplary aspects of a lamination process. In the following description, for purposes of explanation, specific details are set forth in order to promote a thorough understanding of one or more aspects of the disclosure. It may be evident in some or all instances, however, that many aspects described below can be practiced without adopting the specific design details described herein.

A conventional laminated glazing may include a first glass sheet, an interlayer, and a second glass sheet laminated together. The thickness of the glass sheets is not particularly limited, but is preferably from 0.5 mm to 3 mm, more preferably from 1 mm to 2.5 mm. The glass sheets may include, without limitation, soda-lime silicate glass described by ISO 16293- 1:2008. The glass sheets may be bent to a desired shape prior to lamination with an interlayer therebetween. Glass bending may preferably occur by heat treatment from 550°C to 700°C, more preferably from 580°C to 660°C.

An interlayer may include a polymer adhesive, such as polyvinyl butyral (PVB) or any other suitable laminating material, including ethylene vinyl acetate (EVA). The glass sheets and interlayer may be stacked to provide a lamination stack which may then be deaired prior to autoclaving. The deairing process may use mechanical pressure and/or vacuum to remove air from between the glass sheets. In some laminated glazings, the interlayer may have an embossed surface which may facilitate removal of air in the lamination stack. The embossing may provide pathways for the air to reach a lamination stack edge to improve air removal. The interlayer may seal together the lamination stack layers such that no additional air may be introduced into the lamination stack. After deairing, including sealing at the interlayer, there may be some air remaining in the stack which may be dissolved into the interlayer material during an autoclave cycle, which may include high pressure and temperature (such as 10 to 15 bar and 110°C to 160°C).

Some laminated glazings may further include a film laminated between the first and second glass sheets. Particularly, a film may be positioned between two interlayers positioned between two glass sheets. A film may be used for various applications, including heat control, a printed pattern, or a HUD. The film may include a base film which can be any suitable material, including polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate, polyimide, cellulose triacetate (TAC), or others, and may include a coating or print thereon or other additional layers. The film may further include a functional layer on the base film, such as a liquid crystal material, retardation film (wave plate film), a multilayer stack of thin films, or an infrared reflective coating. Preferably, the base film may include PET or TAC. However, the film may create difficulty in lamination. Particularly, the laminated film may present with defects, such as wrinkles. Wrinkles may form where a film produced as a flat shape is conformed to a bent shape, such as in an automotive glazing. The film may not have the elasticity to readily conform to a complex bend. Particularly, some automotive glazings may include areas of particularly high bending (e.g., areas having a small radius of curvature) which may be prone to inducing wrinkles. Further, some films suitable for automotive glazings may expand at temperatures used during a lamination process. A typical lamination process may include heating the lamination materials, including during an autoclave process. Where the film expands at lamination temperatures, the film may further form wrinkles. The interlayer material may be softened at such temperatures, providing a softened surface towards which the film may wrinkle. The wrinkles may be visible in a laminated glazing, which interrupt a driver’s view and be aesthetically undesirable. Where a laminated film is used for HUDs, the defects may further be visible in an image of the HUD. Thus, there is a need in the art to provide a lamination process for eliminating or minimizing such wrinkles.

Among other aspects, the present disclosure relates to a method of preparing a laminated glazing having a film therein with minimized or no wrinkles. A method herein may include providing a functional film on a first glass sheet. The functional film may include an adhesive layer on a major surface of the functional film, such that the adhesive layer may be positioned facing the first glass sheet. The adhesive layer may be positioned between the functional film and the first glass sheet. The method herein may include providing the functional film including the adhesive layer on the first glass sheet. FIG. 1 illustrates a first glass sheet 11 and a functional film 12, and the functional film 12 includes an adhesive layer 13 on a major surface of the functional film 12.

In some embodiments, the first glass sheet 11 may be provided on a support structure. A majority of or an entire major surface of the first glass sheet 11 may be covered with the functional film 12. Preferably, in an automotive glazing, a functional film 12 may be a film that reflects a projected image from a vehicle cabin, and is not particularly limited and may serve other functions. The functional film 12 may include, for example, a P-polarized reflective film, a holographic film, a polarization rotator, and the like. The functional film 12 may have a thickness from 10 pm to 300 pm, preferably from 30 pm to 250 pm, and more preferably from 50 pm to 150 pm. The functional film 12 may be transparent to visible light. The adhesive layer 13 may include any suitable adhesive for adhering the functional film 12 to a glass substrate 11. The adhesive may have suitable optical properties for the glazing, including optical transparency and low haze. The adhesive may be the same or different from an interlayer polymer adhesive. The adhesive may include compounds based on acrylate, urethane, urethane acrylate, epoxy, epoxy acrylate, acryl, silicone, isocyanate, polyolefin, modified olefin, polypropylene, ethylene vinyl alcohol, vinyl chloride, chloroprene rubber, cyanoacrylate, polyamide, polyimide, polystyrene, polyvinyl butyral, or the like. The adhesive layer 13 may have a thickness from 1 pm to 300 pm, preferably, 150 pm or less, more preferably 100 pm or less, and even more preferably 50 pm or less.

The adhesive layer 13 may adhere with heat, pressure, ultraviolet light, infrared light, or visible light. The adhesive layer 13 may not be tacky prior to application of an activator, such as a light source or heat. The functional film adhesive may be treated by a surface activation process to improve adhesion to the adjacent glass surface. This surface activation process may include a plasma treatment by molecular plasma beam. In some embodiments, the glass surface may be treated by the plasma treatment and/or a fine polishing using cerium oxide.

In a method of laminating the functional film 12, the functional film 12 may be covered with a press, which may include a mold, such that the functional film is pressed between the first glass sheet 11 and the mold 21, as shown in FIG. 2. FIG. 2 illustrates an assembly 1 including the first glass sheet 11, the functional film 12, the adhesive layer 13, and a mold 21. The mold 21 may include an outer mold 22 and a support 23. The outer mold 22 may face the functional film 12. The first glass sheet 11 may be bent to a desired shape, which may include areas of high bending, prior to application of the functional film 12. The mold 21 may have a shape, or may take a shape, such that it can smoothly fit to the bent first glass sheet 11. The first glass sheet 11 may have a curved shape, and the mold 21 may fit to a convex surface of the first glass sheet 11. FIG. 3 illustrates an assembly 2 in which the first glass sheet 11 is bent to a curved shape, prior to application of the functional film 12. In some other embodiments, the functional film 12 may be adhered to the concave surface of the first glass sheet 11 and the mold 21 may be shaped to fit such a concave shape.

In an embodiment of the present disclosure, even where a film 12 expands at some temperatures, such a film 12 may shrink at higher temperatures. The shrinking of the film 12 may provide for the film 12 to eliminate or minimize wrinkles and conform to the shape of a first glass sheet 11. Heat may be applied to an assembly including a first glass sheet 11, film 12, adhesive 13, and mold 21, wherein the treatment reaches a temperature of at least a shrinking temperature of the functional film 12. Preferably, the film 12 may shrink and adhere to the glass sheet 11 during this process. Preferably, the assembly 1, 2 may be heated from 85°C to 200°C, more preferably from 90°C to 150°C. The assembly 1, 2 may be heated from 115°C to 200°C. Preferably the assembly 1, 2 may be treated with heat and pressure for at least 20 minutes, more preferably at least 30 minutes. Pressure applied to the shrunk or shrinking film 12 may help to flatten the film 12 and provide minimal or no wrinkles in the film 12. Pressure may be applied mechanically via the mold 21.

In another embodiment of the present disclosure, even where a film 12 expands at some temperatures, such a film 12 may conform to a desired shape under pressure. The pressure on the film 12 may provide for the film 12 to eliminate or minimize wrinkles and conform to the shape of a first glass sheet 11. The pressure may be generated by applying a vacuum to the glass stack and/or by a press. Pressure by vacuum may be preferably from 0.85 to 1.10 bar. Preferably the assembly 1, 2 may be treated with pressure for at least 20 minutes, more preferably at least 30 minutes, and preferably less than 2 hours, more preferably less than 1.5 hours. Preferably, where the adhesive is heat activated, the assembly 1, 2 may be heated with pressure to a temperature from 85°C to 120°C, more preferably from 90°C to 110°C. The assembly 1, 2 may be heated with pressure to a temperature from 90°C to 120°C. Where the adhesive layer 13 on the functional film 12 is otherwise cured, it may be treated to provide such curing when the film 12 is flattened against the glass sheet 11. In some embodiments, the functional film adhesive layer 13 may be set such that the functional film 12 without wrinkles may remain in such a shape on the first glass sheet 11. Preferably, in an automotive glazing, the first glass sheet 11 may be an inner glass sheet facing a vehicle interior when installed. However, where the functional film 12 is adhered to a concave surface of the first glass sheet 11, the first glass sheet 11 may preferably be an outer glass sheet facing a vehicle exterior.

A press to be used herein may include one or multiple mold pieces. The outer mold 22 facing the functional film 12 may preferably have a smooth surface. The outer mold 22 may further be non-adhesive such that the mold 21 may be removed from the functional film 12 without disturbing the functional film surface. The surface of outer mold 22 may be non- adhesive to the functional film 12. The outer mold 22 may include any suitable material for these means, including PET or a fluoropolymer, such as polytetrafluoroethylene. In some further embodiments, the mold 21 may include a liner 24 and a soft cushion material 25, as shown in FIG. 4. FIG. 4 illustrates an assembly 3 in which the mold 21 includes a liner 24, a cushion material 25, and a support 23. The liner 24 may face the functional film 12. The liner 24 may include PET or a fluoropolymer, such as polytetrafluoroethylene. Preferably the liner 24 may have a thickness of at least 50 pm, more preferably, the liner 24 has a thickness of from 100 pm to 500 pm. The cushion material 25 may be positioned between the liner 24 and the support 23 and may be softer than the liner 24. In other words, the cushion material 25 has a smaller Young's modulus than the liner 24. The cushion material 25 may include a cloth material, silicone or silicone foam, ethylene propylene terpolymer, synthetic rubber, elastomers such as fluoropolymer elastomer, or an interlayer material including a polymer adhesive such as PVB. The liner 24 may face the functional film 12 and have a smooth surface. The mold 21 may include a support 23 attached to an outer mold 22 or a cushion material 25, as shown in FIGs. 2 to 4. The support 23 may be made of, for example, glass, plastic, metal, ceramic, or the like. Where the support 23 is not attached to the outer mold 22 or cushion material 25, the support 23 may be a second glass sheet for laminating to the first glass sheet 11. In some embodiments, the support 23 may have a same surface shape as the second glass sheet for fitting to a functional film 12 and first glass sheet 11 and may be attached to the mold outer surface material 25 permanently or replaceably. The support 23 preferably may have a shape matching that of the first glass sheet 11 such that even pressure may be applied across the functional film 12. The first glass sheet 11 may have a curved shape, and the support 23 may fit to a convex surface of the first glass sheet 11.

After the functional film 12 is flattened and adhered to the first glass sheet 11, the mold 21 may be removed from the functional film 12, as shown in FIG. 5. An interlayer 14 and the second glass sheet 16 may be positioned against the functional film 12 to provide a lamination stack. The lamination stack may then be deaired and autoclaved. A deairing process may include methods known in the art, including the use of rollers, vacuum bags, or vacuum rings. The deairing process may include pressure and heat to remove air from between the glass sheets and to seal the lamination stack, preventing the reentry of air into the stack. Autoclaving the lamination stack may further include methods known in the art and the application of pressure and heat on the lamination stack to provide a laminated glazing 10, as shown in FIG. 6. FIG. 6 illustrates a laminated glazing 10 including a first glass sheet 11, an adhesive layer 13, a functional film 12, an interlayer 14, and a second glass sheet 15. Preferably, in an automotive glazing, the first glass sheet 11 may be an inner glass sheet, and the second glass sheet 15 may be an outer glass sheet. In some other glazings, the first glass sheet 11 may be an outer glass sheet and the second glass sheet 15 may be an inner glass sheet. The laminated glazing 10 may be a windshield.

The above description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the common principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Further, the above description in connection with the drawings describes examples and does not represent the only examples that may be implemented or that are within the scope of the claims.

Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and/or embodiment may be utilized with all or a portion of any other aspect and/or embodiment, unless stated otherwise. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.