FR2638449A1 - Process and device for the production of a multilayer laminated glass - Google Patents

Abstract

Process for integrally joining, by a heat energy input, a plurality of successive layers of glass and of a thermoplastic intermediate binder, characterised in that the energy is introduced by an energy flow of short infrared defined in relation to the peak of maximum wavelength at 1.2 microns according to Wien's law.

Description

 The present invention relates to a method and a device for the joining by thermal energy supply of a plurality of alternating layers of glass and a thermoplastic intermediate binder, in particular for the production of a multilayer laminated glass.

 To obtain a laminated glass of this type, the finishing of which requires a certain number of operations such as calendering, etc. which are not involved in understanding the present invention and will therefore not be described, it is necessary to provide thermal energy in the most uniform and intense manner possible over a large area and over a relatively large thickness of material.

 By implementing methods with heat transfer fluid, the temperature gradient is such that the central part is almost untreated, which causes, in an industrial process, a significant rejection of non-conforming products.

 With processes using a thermal input using medium infrared, the result is almost identical, contrary to what a person skilled in the art would have thought, because the absorption of average IR by the intermediate binder and the glass is very high. . The radiation flux reaching the center of the structure to be treated is therefore minimal and in practice insufficient.

 We admit that the I.R. mean corresponds in this case to an average wavelength corresponding to the maximum peak at 2.7 microns according to Wien's law.

 Surprisingly, it was found that this problem could be solved, thus allowing - an almost homogeneous distribution on the surface and in depth of the heat energy - consequently, an optimal industrialization of the process with lower costs in terms of material and investments.

 According to the invention, in fact, a method is proposed for securing by the supply of thermal energy a plurality of successive layers of glass and a thermoplastic intermediate binder, in particular for producing a multilayer laminated glass. , characterized in that the energy is provided by a short infrared energy flux, defined with respect to the peak of maximum wavelength at 1.2 microns according to Wien's law.

 As a result, it can be seen that the energy is released more uniformly in the different layers of thermoplastic intermediate binder, in particular of P.V.B. characterized by a much more uniform temperature of the different layers of thermoplastic binder.

 In addition, the I.R. short allows, due to the devices used, a very rapid release of energy (a few seconds) while by heat transfer fluids it takes a preparation time and temperature rise of several hours.

 The invention will be better understood with the aid of the description given below with reference to the appended drawings in which - FIG. 1 diagrams the thermal gradient by heat transfer fluid - FIG. 2 diagrams the thermal gradient by average IR - FIG. 3 diagrams the thermal gradient by short IR.

 The description below should be considered as schematic, taking into account certain theoretical approximations allowing an understandable explanation of the invention.

 Referring to Figure 1, there is shown a plurality of alternating layers of glass (1) and a thermoplastic binder (2).

 The heat transfer gas heating system shown diagrammatically by (3) and (3 ') on the two faces of the stack generates in said stack a temperature gradient such that the maximum is obtained on the external ends of the stack and that the part the weakest is the heart point (4) of it.

 In the same way (figure 2) with an average IR radiation, if we suppose a 100% transparency of the glass compared to this one, the absorption by the P.V.B. is very important. The temperature gradient remains identical to that of a heat transfer fluid.

 With I.R. short, as shown in Figure 3, the absorption (always assumed to be 0% by the glass, therefore 100% transparency) is 20 to 30% by the P.V.B., each time a layer is passed.

 The portion of energy flow arriving during stacking therefore remains large and also covers a large flow area.

 For a device comprising a plurality of I.R generators. short additionally arranged on each side of the stack, one therefore obtains a completely satisfactory result from an energy point of view, therefore qualitative, on all of the surfaces and the thickness of the stack to be treated.

 The implementation of the I.R. short allows - a better output, - an instantaneous emission of power guaranteeing a speed of production and an energy saving.

 Investments are significantly lower and maintenance very low.

 The sources of I.R. used can for example be of the type described in patent EP 0127496 in the name of the inventor.

 The invention finds a particularly advantageous application in the manufacture of laminated glazing with very high resistance.

Claims (2)

1. Method for securing by supplying thermal energy to a plurality of successive layers of glass and a thermoplastic intermediate binder, in particular for producing a multilayer laminated glass, characterized in that the energy is supplied by a short infrared energy flow, defined with respect to the maximum wavelength peak at 1.2 microns according to Wien's law. 2. Device for implementing the method according to claim 1, characterized in that it comprises a plurality of short infrared generators arranged on each side of the layers of glass and binder,