MXPA96003228A - Laminated glass glass with repellent properties - Google Patents

Abstract

The present invention relates to laminated glass crystal, comprising: a) two sheets of glass, b) a transparent support film of a tear-resistant polymer provided with an IR-reflective surface coating, and c) a first and a second adhesive layers placed on opposite surfaces of the coated backing film, wherein the two glass sheets have placed between them the coated backing film and the first and second adhesive layers, and the coated backing film is joined to the two backing sheets of glass by the first and the second adhesive layers, and wherein the first adhesive layer has a thickness of at most 50 μm, and the IR reflective layer is deposited on the face of the support film in contact with the second adhesive layer.

Description

LAMINATED GLASS GLASS WITH REFLECTIVE PROPERTIES IR D E S C R I P C I O N This invention relates to an IR reflecting laminated glass pane consisting of two glass sheets, a transparent support film of a tear resistant polymer disposed between the two glass sheets and provided with a reflective surface coating IR, and two adhesive layers by means of which the coated film is connected to the two sheets of glass. Crystals of laminated glass of this type are known, for example, from DE-2344616 Al, EP-0371949 Al and EP-0391165 A2. These crystals are particularly suitable as heat shield glasses for automobiles. The support film for the reflective surface coating IR can basically be made of various materials, such as, for example, polyester, polycarbonate, cellulose acetate, acrylate or polyvinyl chloride. For this purpose, polyethylene terephthalate (PET) support films have proved particularly suitable. The IR reflective surface coating can also be basically of various types. Generally common are the types of multiple layers that comprise a layer or more thin layers of silver as a real functional layer, which are embedded between metal or dielectric layers, these layers preferably being applied by the method of cathodic sputter metallization with help of magnetic field. For the production of laminated glass panes, the backing films provided with the surface coating are connected to the two glass sheets by two thermoplastic adhesive coatings by the usual laminated glass process, with the polyvinyl butyral films being usually employed as thermoplastic adhesive layers. Advantageously the thermoplastic polyvinyl butyral films are first bonded to the coated support film to form a laminate, although of course, the different films can also be prepared separately and can only be bonded together in the production of laminated glass glass to form a laminated package. In the actual bonding process, the layer stack first has to be removed from the air and then thought of in an autoclave by the use of heat and pressure, that is, commonly at a temperature of 120 to 150 ° C and at a pressure of 8 to 15 atmospheres Laminated glass panes of this type when subject to oblique light incidence often present an optically troublesome phenomenon since the IR reflecting surface does not appear uniform in reflection, but has a shrinking effect and an annoying effect. This effect is well known and is also described in the literature. It is also known that this annoying effect is apparently the result of a shrinking operation of the ion support film of the thermoplastic adhesive films during heating in the bonding process. To reduce this annoying optical effect it has been proposed to use support films having only a very low degree of shrinkage, in US-PS-4456736. In EP-0371949 Al, it has been proposed that the aforementioned effect can be counteracted with an IR reflective surface coating so that the reflection in the scale of the visible spectrum is limited to more than 2% and preferably to at least 7%. The modification to the layer caused by the shrinking truly remains as a whole, although the shrinking effect is then no longer visible to the eye to a disturbing degree. Also for the purpose of avoiding this optically troublesome effect, EP-0544717 Bl proposes the use of special adhesive layers. According to this proposition, polyvinyl butyral films are used as adhesive layers, these films having, on the contact face with the IR reflector coating, a wavy pattern of small, defined surfaces. The known proposals to avoid the aforementioned optically troublesome effect each have specific disadvantages and the problem of the annoying effect in laminated glass panes of this category to date has not been satisfactorily resolved., even with the realization of these known propositions. The object of the present invention, therefore, is to construct a laminated glass crystal of the type initially established in such a way that the optically disturbing effects produced by the shrinkage of a polymer layer disposed between the silicate glass sheets can be avoided. by taking comparatively simple measures. According to the invention, this object is achieved in that at least one of the adhesive layers has a thickness of at most 50 microns. It has been found and confirmed by the experiment that the optical disturbing effects observed are complete or at least largely avoided if the coated support film is glued on at least one side comparatively firmly to a glass sheet by a layer very thin adhesive. In this way, the support film can no longer be deformed or shrunk because this is prevented by the firm connection to one of the two glass sheets. They do not matter here if the shrinking operations, which are also in accordance with our experience responsible for the annoying effect, are performed mainly on the same support film provided with the coating or on the adhesive layers. It is really known in the case of polyvinyl butyral films that these films are always subjected to internal stresses and that they relax and deform under the action of heat. Therefore, it is not impossible for the shrinkage operations responsible for the effect to be carried out mainly on the polyvinyl butyral films and transferred from here to the supporting film. The disruptive effects resulting from the measures according to this invention are also avoided. In the known laminated glass panes of this category, for each of the two adhesive layers the polyvinyl butyral films generally used for the production of laminated glass panes are used in the thickness of 0.38 mm which are commercially available. It has also been shown that the purpose pursued by this invention is also achieved if only one of the two adhesive layers is constructed extremely thin and for the other of the adhesive layers a commercially thick adhesive sheet is used. For the other adhesive layer, in particular, a 0.76 mm thick polyvinyl butyral film can also be used. A total thickness of the polyvinyl butyral layer of 0.76 mm is, for example, specified for biomechanical reasons in the case of windshields.

Both for the extremely thin adhesive layer and also for the other adhesive layer, basically any of the known materials of normal laminated glass can be considered for the adhesive layers. In particular, tested materials such as thermoplastic polyvinyl butyrals and thermoplastic polyurethanes can be used for this purpose. In any case, thermoplastic materials will be used so that the usual production process can be adopted without modification. In a further advantageous embodiment of the invention, the thickness of the adhesive thin layer is from 1 to 30 microns, and preferably from 5 to 10 microns. Under these circumstances, a particularly good fixing of the support film to a glass pane is achieved. An exemplary embodiment of the invention will be described in greater detail in what follows with reference to the attached single figure. The drawing shows a partial sectional view of a laminated glass pane constructed in accordance with this invention. Unimportant and generally known details for carrying out the invention such as, for example, the special construction of the IR reflector layer, the arrangement of the bonding coatings, the composition of the support film, measures to prevent corrosion of the IR reflector layer on the edge, etc., is not described because they form part of the state of the art. The composite glass pane comprises the two sheets 1 and 2 of glass, each for example 3 mm thick float glass, the support film 4 provided by the cover 3 of the IR reflecting surface, the thin adhesive layer 5 and one comparatively thick adhesive layer 6 joining the film 4 to the two sheets of glass. The support film 4 is for example a polyethylene terephthalate film 50 microns thick. The support film 4 is provided on one face with a multiple IR reflecting layer, with the actual functional layer within the multiple layer being silver. The adhesive layer 5 that joins the film 4 to support the glass sheet 1 is made of thermoplastic polyvinyl butyral and has a thickness of 10 microns. The adhesive layer 6 on the other side of the support film 4 has a thickness of 760 microns and is also made of thermoplastic polyvinyl butyral. The coated backing film 4 has been laminated in a preceding operation with a film thickness of 0.76 mm of polyvinyl butyral and coated on the other side with another adhesive film with a thickness of 10 microns. The two sheets 1 and 2 of glass are joined by this laminate thus prepared one to the other in an autoclave at a temperature of 140 ° C and a pressure of 12 gauge atmospheres.

Claims (6)

R E I V I N D I C A C I O N S

1. - Laminated glass crystal having IR reflective properties, consisting of two glass sheets, a transparent support film of a tear resistant polymer disposed between the two glass sheets and provided with an IR reflective surface layer, and two adhesive layers, by means of which the coated support film is joined to the two glass sheets, characterized in that at least one adhesive layer has a thickness of at most 50 microns.

2. Laminated glass crystal according to clause 1, characterized in that the adhesive layer has a thickness of 1 to 30 microns, preferably 5 to 10 microns.

3. Laminated glass crystal according to clause 1 or 2, characterized in that the other adhesive layer has a thickness of 0.3 to 0.8 mm.

4. Laminated glass crystal according to clauses 1 to 3, characterized in that the adhesive layers are made of a thermoplastic polymer, such as polyvinyl butyral or polyurethane.

5. Laminated glass crystal according to clauses 1 to 4, characterized in that the support film is made of polyethylene terphthalate.

6. Laminated glass crystal according to clauses 1 to 5, characterized in that the IR reflecting layer is a multiple layer produced by the cathodic sputtering process and comprising at least one layer of silver as a functional layer, SUMMARY A laminated glass pane consisting of two sheets of glass (1, 2) and a transparent support film (4) having an IR reflective surface coating (3), connected to two sheets of glass (1, 2). ) by adhesive layers (5, 6), an adhesive layer (5) has a thickness of at most 50 microns. The other adhesive layer (6) preferably has a thickness of 0.76 mm.