FR3088577A1 - PROCESS FOR THE MANUFACTURE OF A LAMINATED GLAZING OF WHICH A SIDE AT LEAST OF THE STACKING OF THE CONSTITUENTS IS EXPOSED TO A RADIATION OF SELECTED SPECTRUM IN TWO NARROW DEFINED AREAS - Google Patents

Abstract

The invention relates to a method of manufacturing laminated glazing, comprising the steps of - stacking successively in direct contact with one another a first sheet of glass, a first adhesive interlayer sheet, optionally a stack of outer glass sheets other glass sheets and other intermediate adhesive sheets, a second intermediate adhesive sheet and a second glass sheet, - exposing at least one of the two main faces of the assembly thus formed to a radiation of lengths of waves between 340 and 400 nm, and / or between 1.6 and 2.9 µm, so as to heat said adhesive interlayer sheets through the glass sheets, to a temperature sufficient to adhere to the glass or between them after passing between the rollers of a calender, then to - subject this assembly to a pressure by calendering.

Description

PROCESS FOR THE MANUFACTURE OF A LAMINATED GLAZING OF WHICH A SIDE AT LEAST OF THE STACKING OF THE CONSTITUENTS IS EXPOSED TO A RADIATION OF SELECTED SPECTRUM IN TWO NARROW DEFINED AREAS

The invention is in the field of the processing of possibly curved flat glass (laminating) and more particularly the heating of the laminated assembly during the deaeration step comprising a calendering of the laminated glass before going to the autoclave.

Good quality laminated glass at the end of the line must be transparent and bubble-free. To achieve this state, the laminating process currently comprises two first steps performed online (scrolling of the glasses), assembly and deaeration (preheating with a radiant oven and calender). The deaeration allows the adhesion of the interlayer adhesive of the polyvinyl butyral type (PVB) or equivalent and of the glass thanks to the use of infrared lamps which heat the stack and one or more calenders which press it. It has the effect of eliminating most of the air present in the PVB or equivalent and between it and the two glass sheets. At the end of these two stages, the glasses must be lifted and stacked offline on easels until they can fill an autoclave and start a pressure and temperature cycle that lasts several hours.

In the autoclave, the glasses are pressurized (around 10 bar for example) and heated to about 140 ° C in order to obtain the transparency of the laminated glass.

The object of the invention relates to this first stage of heating before calendering. Traditionally the heating of the laminate is done in an oven equipped with infrared lamps, black body spectrum corresponding to filament temperatures between 900 and 1200 ° C (IR lamps).

The state of the art has the disadvantage of requiring a lot of energy to heat the entire package (glass / PVB / glass) before the calender.

On a typical line, infrared lamps are used for a distance of 4 to 10 m, for example, inside an oven. However, the interlayer adhesive (such as PVB) absorbs little of the infrared radiation from these lamps, or in proportions comparable to the absorption of the glass sheet. The proportion of energy of the infrared radiation from these lamps absorbed by the glass increases exponentially with its thickness, and only the remaining part of the energy from the lamps is used to heat the interlayer adhesive. This implies a higher heating for assemblies with thicker glass.

Also in the case of glasses with a thin layer of solar control or low-emissivity type, most of the infrared heat is reflected and the process becomes highly inefficient.

The inventors have discovered the possibility of achieving excellent deaeration by exposing the glass / interlayer adhesive / glass stacks to selected spectrum radiation in two particular wavelength ranges, narrower than that of the black body spectrum. They were able to heat the interlayer adhesive directly, transferring the energy directly to its interface with the glass. This saves energy, especially for stacks with thick glass.

To this end, the invention therefore relates to a method of manufacturing a laminated glazing, characterized in that it comprises the operations consisting of

- successively stacking in direct contact with each other a first glass sheet, a first interlayer adhesive sheet, possibly a stack of other glass sheets and other interlayer adhesive sheets, optional stacking with outer glass sheets, a second interlayer adhesive sheet and a second glass sheet,

- expose at least one of the two main faces of the assembly thus formed to radiation of wavelengths between 340 and

400 nm, and / or between 1.6 and 2.9 μιτι, these latter wavelengths being effective only when they are used below layers with low transmission in these wavelengths, layers supported by glass sheets, so as to heat the said intermediate adhesive sheets through the glass sheets, to a temperature sufficient to adhere to the glass or between them after passing between the rollers of a calender, then to

- subjecting this assembly to a pressure by calendering or equivalent, so as to eliminate a major part of the air initially present in the adhesive adhesive sheets, between them and between each of these and the sheet or sheets ) of glass which is (are) adjacent to it, and to obtain adhesion between all of the stacked constituents.

Two sources of radiation are therefore used, one on each side of the stack, or else only one on one side, making it possible to directly heat the surface of the interlayer adhesive sheet closest to each source of radiation, at its interface. with said first or said second sheet of glass.

At the selected wavelengths of the invention, the interlayer adhesive such as PVB absorbs much more than glass. A major advantage of the invention lies in the efficiency of radiation heating in the particular wavelengths identified, of a thin thickness of said first (respectively second) adhesive sheet interleaved at its interface with said first (respectively second) sheet of glass, regardless of the glass thickness of the latter to pass through. It should be noted, in particular, that this effectiveness remains for significant thicknesses of the sheets of glass and of interlayer adhesive, in contrast to heating with the IR lamps currently used.

The manufacturing process of the invention does not exclude the use of auxiliary heating means, such as infrared lamps.

According to preferred characteristics of the process of the invention:

said other glass sheets and other interlayer adhesive sheets consist of a single third glass sheet; the method of the invention also makes it possible to obtain good adhesion of this third glass sheet with the two intermediate adhesive sheets which are adjacent to it, by heat transfer by conduction;

said other glass sheets and other intermediate adhesive sheets do not exist, and said first and second intermediate adhesive sheets are only one and the same sheet; however, it is also possible that said first and second interlayer adhesive sheets are separate, which makes it possible to adjust the thickness of interlayer adhesive used between said first and second sheets of glass; the method of the invention advantageously makes it possible to obtain good adhesion between these two intermediate adhesive sheets;

at least one of the two main faces of said assembly thus formed is exposed to radiation of wavelengths between 340 and 400 nm and / or 2.2 and 2.7 pm;

- the assembly of the glass sheets and the interlayer adhesive sheet (s) is then raised and placed on an easel; this is made possible by the excellent mutual adhesion between them;

- said radiation is produced by a coherent or incoherent source;

- said radiation of wavelengths between 340 and 400 nm is produced by LED lamp or curtain, curtain or laser beam;

said radiation of wavelengths between 340 and 400 nm, and / or between 1.6 and 2.9 pm has a spectral width of at most 100 and, in order of increasing preference, at most 80, 50 nm;

- the interlayer adhesive sheets are chosen from polyvinyl butyral (PVB), polyurethane (PU), ethylene - vinyl acetate (EVA), ionomer such as poly (acrylic acid) partially neutralized (for example sold under the registered trademark SentryGlas® by Kuraray Company) alone or as a mixture of several of them; these polymeric materials can include variable amounts of plasticizers, and consist of varieties with sound attenuation / insulation properties.

The invention will be better understood in the light of Figures 1, 2 and 3 which represent transmission spectra of a glass sheet, with and without a functional layer, and absorption spectra of a polyvinyl butyral sheet.

In the three Figures or graphs, the wavelength in microns is shown on the abscissa and the fraction of light transmitted or absorbed as the case may be on the ordinate.

In FIG. 1, the solid line represents the absorption of a 0.76 mm thick PVB sheet, marketed by the Eastman Chemical Company under the registered trademark Saflex® RB41, and the dotted line the transmission of '' a 4 mm thick glass sheet sold by the Saint-Gobain Glass Company under the registered brand Planiclear®.

For UV radiation between 340 and 400 nm, the glass is transparent and the PVB very absorbent, as shown in Fig.1. The spectral window around 365 nm is therefore ideal for directly heating the PVB without the radiation being absorbed by the glass. Selective heating reduces the absorption of radiation in areas other than the glass / PVB interface and therefore reduces the energy used, thereby reducing the costs of the process.

A UV source positioned before the grille allows the temperature of the interface between the PVB and the glass to be rapidly increased. It is possible, with the pressure applied by the calender, to deaerate the sample immediately. UV energy is fully absorbed by PVB. This method saves energy and eliminates the inertia typical of infrared ovens. The response time of UV lamps is fast enough to be able to switch them off between two productions or between two glasses.

In Figure 2, the single dashed line represents the product of the two curves in Figure 1, that is, the portion of radiation that is transmitted by the glass and then absorbed by the PVB. The two favorable wavelength ranges according to the invention are observed, between 340 and 400 nm, and between 1.6 and 2.9 pm.

In Figure 3, the dotted line represents the transmission of a thin “low-e” / “low emissivity” layer marketed by the Saint-Gobain Glass Company under the brand Planitherm® ONE, on a 4 mm glass sheet. thick. The dashed line represents the product of the dashed line curve in Figure 2 and that of the transmission of the low emissivity layer in Figure 3, i.e. the part of radiation that is transmitted by the thin layer, the glass then absorbed by the PVB.

For assemblies of this type comprising thin layers reflecting infrared radiation, the glass transmission window is preserved and the efficiency of the process is only slightly affected by the addition of the thin layer on the glass in the field of wavelengths between 340 and 400 nm, but not between 1.6 and 2.9 pm. In this case, the thin layer transmits little wavelengths between 1.6 and 2.9 pm, of which it reflects a good part, and only radiation of wavelengths between 340 and 400 nm is able to be transmitted through this thin layer.

According to the invention, an assembly of Planiclear® glass (SG Glass) 2mm / PVB Saflex® RB41 0.76 mm (Eastman Chemical Company) / Planiclear® glass 2 mm is insulated on one side with a UV LED lamp emitting a power maximum surface area of 9 W / cm ² at a wavelength of 365 nm (at least 90% of the total light energy is emitted in the spectral band from 345 to 385 nm). The sample scrolls at 0.4 m / min under the lamp and in a calender. The lamp is located 5 cm before the calender at a distance of 3 mm from the sample, which is irradiated over its entire width, and over the length of the irradiation zone, which is 20 mm.

After the deaeration thus carried out, the sample has a blur measured around 55-70% and a clarity measured around 65-80%, comparable to what is obtained with the usual methods of deaeration (haze 87% and clarity 8% before deaeration). After autoclave, the sample is perfectly transparent and bubble-free.

Claims (9)

1. A method of manufacturing laminated glazing, characterized in that it comprises the operations consisting of - successively stacking in direct contact with each other a first glass sheet, a first interlayer adhesive sheet, possibly a stack of other glass sheets and other interlayer adhesive sheets, optional stacking with outer glass sheets, a second interlayer adhesive sheet and a second glass sheet, - expose at least one of the two main faces of the assembly thus formed to radiation of wavelengths between 340 and 400 nm, and / or between 1.6 and 2.9 pm, these latter lengths of waves only being effective when they are used alone below layers with low transmission in these wavelengths, layers supported by glass sheets, so as to heat said adhesive sheets interleaved through the glass sheets , at a temperature sufficient to adhere to the glass or between them after passing between the rollers of a calender, then - subjecting this assembly to a pressure by calendering or equivalent, so as to eliminate a major part of the air initially present in the adhesive adhesive sheets, between them and between each of these and the sheet or sheets ) of glass which is (are) adjacent to it, and to obtain adhesion between all of the stacked constituents. 2. Method according to claim 1, characterized in that said other glass sheets and other intermediate adhesive sheets consist of a single third glass sheet. 3. Method according to claim 1, characterized in that said other glass sheets and other intermediate adhesive sheets do not exist, and in that said first and second intermediate adhesive sheets are only one and the same sheet. 4. Method according to one of the preceding claims, characterized in that at least one of the two main faces of said assembly thus formed are exposed to radiation of wavelengths between 340 and 400 nm and / or 2.2 and 2.7 pm. 5. Method according to one of the preceding claims, characterized in that the assembly of the glass sheets and the adhesive sheet (s) interlayer (s) is then raised and placed on an easel. 6. Method according to one of the preceding claims, characterized in that said radiation is produced by a coherent or incoherent source. 7. Method according to one of the preceding claims, characterized in that said radiation of wavelengths between 340 and 400 nm is produced by lamp or LED curtain, curtain or laser beam. 8. Method according to one of the preceding claims, characterized in that said radiation of wavelengths between 340 and 400 nm, and / or between 1.6 and 2.9 pm has a spectral width of at most 100 and, in ascending order of preference, at most 80.50 nm. 9. Method according to one of the preceding claims, characterized in that the intermediate adhesive sheets are chosen from polyvinyl butyral (PVB), polyurethane (PU), ethylene - vinyl acetate (EVA), ionomer alone or in mixtures of several d 'between them.