Stock material or miscellaneous articles – Sheet facing and longitudinally noncoextensive with web or...
Reexamination Certificate
1999-07-26
2002-03-05
Ahmad, Nasser (Department: 1772)
Stock material or miscellaneous articles
Sheet facing and longitudinally noncoextensive with web or...
C052S171300, C052S173300, C428S138000, C428S192000, C428S426000, C428S430000, C428S432000, C428S437000
Reexamination Certificate
active
06352754
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for manufacture of laminated glazing units, especially those designed as equipment for vehicles of the windshield type. It relates more particularly to laminated glazing units in which the intermediate film, which is a polymer-base material disposed between rigid substrates, generally of glass, is provided with a coating having thermal properties, especially of reflection in the infrared, thus endowing these glazing units with a highly satisfactory function of protection against solar radiation.
2. Discussion of the Background
Such configurations of glazing units are known in particular from the following patents: U.S. Pat. No. 4,639,069, U.S. Pat. No. 4,369,945, EP 0303586 and WO 90/08334, wherein there are used intermediate films generally comprising a ply of transparent polymer of the polyethylene terephthalate type (PET), provided on one of its faces with the coating which reflects in the infrared, said ply being inserted between two plies of thermoplastic polymer of the polyvinyl butyral type (PVB) before the usual assembly of this multi-layer intermediate film together with the two glass substrates is performed.
A problem specific to this type of configuration soon became apparent, however: in choosing these “multi-layer intermediate films”, with dimensions identical to those of the glass plates, the infrared-reflecting coating was disposed flush with the edge wall of the glass plates. This coating usually comprises layers which are susceptible to deterioration, especially to oxidation, in contact with moisture. This is particularly true for metallic layers, especially of silver, which tend to corrode along their periphery, such corrosion progressively spreading over their entire surface and leading to optical defects and loss of thermal performances.
Suggestions toward solving this problem have already been made. For example, U.S. Pat. No. 5,131,967 describes a technique using the laser to margin the reflecting coating deposited on the PET, thus preventing it from occupying a flush position. This technique seems to be cumbersome, however, and it substantially lengthens the production time, since the laser must achieve ablation of the reflecting coating over a peripheral strip of non-negligible width.
Another suggestion was made in U.S. Pat. No. 5,320,893: this document teaches making a cut in the thickness of the PET ply, around the periphery thereof, so that the peripheral corrosion of the reflecting coating will be stopped from spreading by this break line. It is not certain that a simple line will be able to prevent all spreading of corrosion in this way.
SUMMARY OF THE INVENTION
The purpose of the invention is therefore new processes for manufacture of this type of glazing unit, wherein the quality of the reflecting coating is preserved in the zones of visibility, while the aforesaid disadvantages are remedied, in particular while being relatively simple to use and at the same time having great efficacy and reliability.
The primary object of the invention, therefore, is a first process for manufacture of a laminated glazing unit comprising at least two rigid substrates of the glass type assembled by an intermediate film comprising at least one ply based on a polymer or polymers provided on at least one of its faces with a thin layer or a stack of thin layers having thermal properties, especially properties of reflection in the infrared. This process includes the following stages:
a)—the intermediate film in “complete” form or already containing at least the ply provided with the thin layer or layers is cut to dimensions essentially identical to or larger than those of at least one of the two substrates,
b)—the said intermediate film is incised through at least the thickness of the ply provided with the thin layer or layers, in such a way as to define, in the said ply, at least one peripheral zone localized between the incision line and the edge thereof,
c)—the intermediate film is assembled in “complete” form between the two substrates possibly by adjoining thereto any polymer ply or plies thereof which was or were missing in case it was not previously in “complete” form,
d)—the peripheral zone or zones is or are detached from the intermediate film by pulling them mechanically,
e)—the laminated glazing unit is then transformed.
Here and throughout the text hereinafter, the thin layer or layers having thermal properties, especially properties of reflection in the infrared, will be referred to as the “functional layer or layers”. Under this term, the invention also comprises one or more thin layers which may also have other properties, especially optical or electrical, in addition to or instead of thermal properties.
Within the meaning of the invention, “assembly” is understood as the operation comprising correctly positioning all the elements of the laminated glazing unit correctly relative to each other before performing the operation in which they are finally unified.
Within the meaning of the invention, “transformation” is understood as the unification operation, which is generally performed with application of pressure and input of heat.
Finally, the intermediate film has already been described as being complete or not complete in stage a). Within the meaning of the invention, “complete” must be understood as the intermediate film already containing all the polymer plies of the final laminated glazing unit, in particular a sequence of the type PVB/PET/functional layer or layers/PET/PVB (or in other words the polymer support of the functional layer or layers already embraces the two plies of polymer of thermoplastic type that will permit assembly thereof with the rigid substrate or substrates of the window-glass type in the final glazing unit). In stage a), it may already be in complete form and contain all of these plies. However, it may also be incomplete, containing only part thereof, the remaining polymer plies then being added during assembly, while superposing them on the “incomplete” intermediate film which has been incised according to stage b).
The “incomplete” intermediate film on which the incision is made may therefore contain only the sequence of the type PVB/PET/functional layer or layers (or in other words the polymer support provided with the functional layer or layers alone or combined in only one of the plies of thermoplastic polymer that will permit assembly thereof with a window-glass substrate or substrates).
In general, therefore, the process according to the invention comprises stages (a) to (e).
According to a first variant, the stages are performed successively in the order in which they were listed hereinabove.
According to a second variant, the order in which these stages are performed may be modified, in particular by reversing the order of stages (c) and (d), or in other words by removing the peripheral zones of the intermediate film incised according to stage (a) before proceeding with assembly. In this way it is possible, in particularly preferred manner, to perform incision according to stage (a) of the incomplete intermediate film, especially of the type PVB/PET/functional layer or layers, then to detach the incised zones, before adjoining to the intermediate film its second PVB ply and assembling it with the two window-glass substrates. (Here and throughout the text hereinafter, the specific term PVB, which is merely an example, must be understood as any ply of thermoplastic polymer, while the specific term PET must be understood as any ply of polymer of flexible type capable of being provided with a functional layer or layers).
The process according to the invention is particularly advantageous: in fact, in the completed laminated glazing unit, the ply provided with the reflecting coating is effectively “margined” when the incision line follows its entire periphery, the margining having been performed in such a way that the reflecting coating (the functional thin layer or layers) is no longer disposed flush with the edge wall of the
Frost Thorsten
Immerschitt Stefan
Kraemling Franz
Leclerco Philippe
Poncet Laurent
Ahmad Nasser
Saint-Gobain Glass France
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