MXPA00012467A - Plastic glazing sheet with added overmoulded plastic material - Google Patents

Abstract

The invention concerns an essentially flat plastic product, at least partly transparent and whereof one part at least of the external surface consists of added overmoulded plastic material. The invention also concerns two methods for making said product, using injection moulding technique and the use of said product as glazing for transport vehicles or buildings.

Description

GLASS OF PLASTIC MATERIAL WITH ADDITION OF PLASTIC MATERIAL OVER-FORMED DESCRIPTION OF THE INVENTION The present invention relates to products of plastic material, essentially flat and at least partially transparent, which are adapted for their high optical quality to an application as crystals. For the constitution of particular crystals, particularly in the domain of buildings or transport vehicles, the replacement of the glass by a plastic material, comprises advantages and disadvantages. With regard to glass, plastic materials are lighter, which is a decisive advantage for urban electric motor vehicles, in that an increase in their autonomy is crucial. In such vehicles, it could even be considered to manufacture complete car doors, including complete sides of the body, including the windows, in plastic material of a single block, and a lower part is optionally described. In a general way, the lightness of the transparent surfaces is interesting relative to modern transport vehicles, to the extent that technical progress goes hand in hand with the integration with the glass of ever more numerous functions (heating of the rear window , radio antenna, de-icing of the windshield, coloring to prevent overheating of the cabin in case of heavy insolation, incorporation of electrochromic compounds, fixing information on the windshield ...), and with glass surfaces without increased interruption. It results in a general numbing of the harmful vehicle in terms of energy consumption. On the other hand, plastic materials are capable of providing, with respect to glass, improved safety conditions, and a protection against superior theft, due to their superior shock resistance. A no less important triumph of plastic materials in relation to glass lies in their superior aptitude to be easily transformed into complex forms. Finally, the ability of the sheets of plastic material to be more or less deformed in a reversible manner, allows consider ways of installation in the bays of the body considerably simplified, with ratchet, on the inside as on the outside of the vehicle. On the contrary, this relatively low stiffness, which has just been mentioned, constitutes, admitting it, an obstacle in relation to glass, in the same way as a transparency and inferior optical properties and, mainly, an ability to be scratched superior. Several approaches have been adopted, up to the present, to try to overcome this triple obstacle. According to a first approximation, flat bands of plastic material are formed by extrusion, a piece is cut to the required dimensions, fixed on a thermoforming device, thermoforming is carried out by contact with at least one solid surface of the mold and, possibly, with the help of compressed air or with suction. Applied devices are bulky and, in particular, of excessive lengths. The yields are revealed relatively small, and the inevitable losses of material. A high quality of the product is achieved only at the price of a difficult set-up of the process and, if necessary, of a supplementary re-machining treatment.

^ H ^^^ b ^^^ - ** - • - - * ¿-1'- On the other hand, the ease of scratching of plastic materials, mentioned above, is such that, in its optical applications or in elements transparent, it is necessary to coat the pieces formed with a hard varnish. It is thus advisable to guarantee an optical quality superior to that obtained by the extrusion mentioned above, included therein after the formation of the hard anti-scratch coating, which must be carried out in perfect industrial conditions. This constitutes the general framework of the invention, in which it solves its own problem: to significantly increase the functions, and thus the possibilities of application and use of the plastic crystals. This object is presently achieved by the invention, which has as its object an essentially flat product of plastic material, at least partially transparent and of which at least one part of the outer surface is constituted by an addition of overmolded plastic material. In other words, the new crystal made available consists essentially of a first plastic material and has at least one overmolded appendix of a second plastic material. They are then put It advantageously benefits the different and sought physical properties of this second plastic material: adhesion to the first plastic material, suitability for elastic deformation, airtightness, reversibility of a durable compression, rigidity, resistance to bending, mechanical strength ( in particular to rupture or compression) ... the addition of overmoulded plastic material can be placed on one or the other of the two faces of the flat product: it can be a base of the interior mirror overmolded on a plastic windshield, or of a positioning, centered or any location appendix, or even of a fixation terminal. According to a preferred variant, at least part of the addition of plastic material is encapsulated at the periphery of the product. This encapsulation consists, eventually, of a peripheral joint, of which an edge that perfectly adapts to the vain of the body, assumes a sealing function, of a fixing terminal, of a peripheral waist that makes it rigid ... According to a preferred embodiment, the product of the invention has a core made of plastic material, an outer cover comprising at least one film of plastic material that supports an anti-scratch layer and disposed on at least one side of the core towards the rear to the edges thereof, inside the surface delimited by the encapsulated peripheral part 5 of the addition of plastic material. In this configuration, the soul assumes the essential of the mechanical properties, particularly the resistance to bending, in the set that is formed with the outer layer (s) and, moreover, when the latter are thin, the thickness of each one is, for example, of the order of 0.25 mm. Its thickness can be of the order of 1 to 10 mm. Your material is selected among thermoplastic materials such such as polycarbonate, poly (methyl methacrylate), ethylene / vinyl acetate copolymer, poly (ethylene glycol terephthalate), poly (butylene glycol terephthalate), polycarbonate / polyester copolymers, polyurethane, cyclo-olefin copolymer Ethylene / norbornene type, or ethylene / cyclopentadiene, ionomer resins, for example an ethylene / acid (meth) acrylic copolymer neutralized by a polyamine, thermosetting or heat shrinkable materials such as polyurethane, polyester unsaturated, ethylene / vinyl acetate copolymer. HE • It has a tendency to select a classic thermoplastic material, preferably injectable, with a relatively low and cheap softening temperature, such as polycarbonate. The core can also be constituted by an association of several thicknesses of the same or of several plastic materials previously mentioned. The thickness of the outer layer, or of each of the two outer layers, is advantageously selected at most equal to 500 μm, preferably comprised between 50 and 300 μm, the outer layer is constituted by one or more films of plastic material thermoformable, between which is interposed, or on which is deposited if at least one functional layer, at least one of these films can on the other hand constitute itself such a functional layer. The thermoformable plastic material of these films belongs appropriately to the group of polycarbonate, polypropylene, poly (methyl methacrylate), ethylene / vinyl acetate copolymer, poly (ethylene glycol terephthalate), poly (butylene glycol terephthalate), polyurethane, polyvinyl butyral, and the cycloolefin copolymer such as ethylene / norbornene, or ethylene / cyclopentadiene, polycarbonate / polyester copolymer, or ionomer resins.

The anti-scratch layer has a thickness of the order of 1 to 10 μm; generally forms the outer surface of the product of the invention. It may be essentially mineral, and consist in particular of polysiloxanes and / or silicon and / or aluminum derivatives, or mixed, such as that consisting of networks of mineral and organic molecular chains intermingled and joined to each other by means of silicon-silicon bonds. carbon. Such a mixed layer has excellent properties of transparency, adhesion and resistance to scratching. It seems that the mineral network gives the coating its hardness and resistance to scratches, the organic network, its elasticity and its resistance to shock. Such varnishes are well known and have been described in published applications EP-A1-0 524 417 and EP-A1-0 718 348 the teachings of which are incorporated herein by reference; some are designated by the term "Ormocer" which is the abbreviation of "Organically Modified Ceramics". It is notable that the cooking temperature of the Ormocers is easily adaptable by varying the relative proportions between the organic polymer fraction and the mineral fraction. The use of a larger number of plastic materials becomes possible to constitute the supporting film. The characteristic according to the preferred embodiment according to which the two outer layers or 5 are arranged on the faces of the core backwards relative to their edges, and more precisely on the inside of the surface delimited by the encapsulated peripheral part of the addition of plastic material, it is advantageous. It allows in effect to make the best possible use of the excellent adhesion of the conventional materials of the encapsulated addition, particularly elastomeric thermoplastic materials, on the polycarbonate and other usual constituent materials of the core. 15 The functional layers capable of being integrated into an external layer are of a varied nature. According to a first possibility, the outer layer of the outer layer, in contact with the environment, contains a hydrophobic / oleophobic agent which thus confers this property on the outer surface of the product. As hydrophobic / oleophobic agent, fluorinated polysilanes are well known, particularly those obtained from precursors comprising at one end a hydrolysable function of alkoxy type, or halogen iritf ^ ttüaMMii &lb serves for chemical bonding to the substrate and a perfluorinated carbon chain at the other end, intended to constitute the outer surface of the product. The hydrophobic / oleophobic agent is, in descending order of preference, incorporated in the anti-scratch layer, which has a chemical structure close to its own, or with which it is at least chemically compatible, or grafted in the form of a thin layer of thickness between 2 and 50 μm, preferably on the anti-scratch layer, or self-supported on a plastic film, such as a polyvinyl fluoride (PVF) or polyvinylidene fluoride (PVDF), to apply advantageously directly on the anti-scratch layer. According to a variant, at least one decoration and / or masking layer covers all or part of the surface of the product, it is positioned in the outer layer, preferably directly under the support film of the anti-scratch layer. This layer can, for example, replace the silk-screen printed decoration frequently deposited on the periphery of the inner layer of the panes, particularly for motor vehicles, in order to mask, for an observer located on the outside of the vehicle, the body elements that they form the frame of the span and the bead of adhesive that is thus protected from degradation by ultraviolet radiation. It can include opaque or transparent decoration elements, which allow to manufacture colored elements attached to the bodywork or interior equipment, logos, etc. The outer layer may be provided with an adhesion layer, in particular on its inner face to ensure fixation with the core, but also between two films or layers of the outer layer. The usual adhesives are polyvinyl butyral, polyurethane or acrylic adhesives. Among the optional main constituents of the outer layer are also the optically selective layers, which are stacked, for example under the decoration and / or masking layer, or on the latter under the film supporting the anti-scratch layer, or else on the anti-scratch layer. These layers are distinguished by a high transmission in the visible domain (wavelengths of 400 to 800 nm) and an absorption and / or a high reflection in the ultraviolet domain (<; 400 nm) and infrared (> 800 nm). These layers may consist of thin metallic layers, for example based on silver, of thicknesses comprised between 2 and 35 nm, separated from each other as well as from other layers or adjacent films by dielectric layers of oxides or indium nitrides, tin, silicon , zinc, titanium, tungsten, tantalum, niobium, aluminum, cyclium ..., thickness usually between 10 and 150 nm. These layers may comprise at least one colored layer in the dough. The set of these layers can be conductive of electricity; can belong to the family of anti-solar stacks, used to limit the contribution of heat by solar radiation to closed spaces or to low-emission stacks, used to the contrary to limit the loss of heat in closed spaces, due to mainly to a transmission of infrared radiation through the crystal. Such stacks are described in patents FR 2 708 926 and EP 0 678 484. According to another variant, the outer layer is provided with a stack of anti-reflective layers. This stack can comprise, for example, a fluoride or an aluminum oxyfluoride capable of being deposited in a thin layer by a vacuum technique of the sputtering type, possibly assisted by a magnetic field. Such a stack is described in patent FR 2 745 284, the teachings of which are incorporated herein by reference. According to other advantageous features of the product of the invention: the outer layer comprises an electrically conductive network, for example, in a polyvinyl butyral or polyurethane adhesive layer, or sandwiched between two of the layers, and which assumes in a known manner the heating-defrosting or antenna function; the material of the encapsulated plastic material addition is an elastomer such as a copolymer of styrene / ethylene / butylene / styrene eventually modified, polyurethane, polyurethane-acrylic alloy, selected for its adhesion to the core, its elasticity, its impact resistance, its color or its translucent character according to the case. It is, in particular, thermoplastic. This material does not need any pre-treatment of the soul's priming. The copolymers of styrene / ethylene / butylene / modified styrene, polyurethane-acrylic alloy are particularly advantageous for their quality of adhesion to plastic materials, and in particular to polycarbonate.

The invention also has as its object a first method of manufacturing the product described above, in which the injection of a first, and after a second plastic material are made in a single mold, the first plastic material is that of the core , and the second that of the encapsulated addition. This procedure has the merit of limiting the number of injection machines applied and the corresponding volume, and of decreasing the duration of the manufacturing, that is to say finally increase the yield. The product does not make the object of any manipulation, nor does it have to be dedusted afterwards. In an advantageous manner, in the plane of The speed of manufacture of the product of the invention, this process comprises a transfer operation by rotation of the product of the injection of the first plastic material, from a first impregnation, where the injection of the first plastic material, in a second impregnation that serves for the subsequent injection of the second plastic material. Of course, a process in which more than two plastic materials are also within the scope of the invention also falls within the scope of the invention. injected successively into a single mold, two The successive injection operations are each separated by a rotation transfer operation as mentioned above. In the case of n injections, a mold comprising n impregnations distributed according to an angular deviation of 2p / n with respect to the axis of rotation can be used. It is more precisely a mold similar to the multi-injection mold of rotating mobile part with impregnation, or rotary loader described in patent FR-B1-2 725 152, the teachings of which are incorporated herein by reference. According to a second method that also falls within the scope of the invention, the product of the invention is manufactured by injecting a first plastic material into a first mold, then transferring the product of this injection to a second mold, in which a second plastic material. This procedure does not exclude supplementary injection operations, separated each time by a transfer or handling of the product. It does not exclude a procedure that successively includes an injection in a mold, the removal of this mold from the product of the injection, the transformation of this mold by lifting removable parts of volume corresponding to that of the next injection, the repositioning of the injection product. in this mold, and finally the next injection. On the other hand, the simultaneous or successive injection of several different plastic materials in fixed position of the mold also forms part of the possibilities opened by the two methods according to the invention. The manufacturing processes of the product of the invention avoid the pitfall of insufficient optical quality of the products normally obtained by extrusion. Preferably, the outer layer or layers comprising its film of plastic material supporting an anti-scratch layer are produced first of all along a support, in such a way that its face provided with the anti-scratch varnish in formation is free of any mechanical contact, at least on its extent for which an optical quality is required. A state of cohesion of the outer layer and a degree of hardening of the intermediate and controllable anti-scratch varnish are then achieved. Depending on this state and this degree, the thermoforming of the outer layers is carried out, always in the absence of any mechanical contact of the face provided with the anti-scratch coating, or on the contrary with contact. It results both in the formation of the outer layer and the finishing of the hardening of the anti-scratch coating. The process leads to a perfect cohesion of the outer layer that is finished during cooling. The or the two thermoformed outer layers are then advantageously held at the bottom of the mold by any appropriate means, such as suction, blow or electrostatic effect, several of these means are possibly associated, before the injection of the first plastic material that constitutes the core of the product of the invention. In the case where the outer layer comprises an electrically conductive network, it is preferably preformed by metal screen printing. Finally, the invention also has objectively the application of the product described above as glass for buildings or transport vehicles, in particular for the automobile. The following examples serve to illustrate the invention.

EXAMPLE 1 On a 250 μm thick film of standard polycarbonate prepared from bisphenol A, marketed by the company BAYER AG under the trademark "Makrolon" and whose glass transition temperature Tg is equal to 145 ° C, it is deposited by flow coating the anti-scratch coating described in the example of the patent application EP-Al-0 718 348 in a liquid film of 20 μm thickness. After drying, this thickness is reduced to 5 μm. The coated support film is then placed on the bottom of a mold, the anti-scratch layer is placed higher; The whole is subjected to a heat treatment of 155 ° C for 30 minutes. An outer layer in the sense of the preferred embodiment of the present invention is then constituted in its almost definitive form. It is placed in the bottom of a first form, in which it is maintained by electrostatic effect, in front of a first impregnation of a rotary loader bi-injection mold comprising two diametrically opposed impregnations with respect to the axis of rotation, as shown in FIG. described in the patent FR-B1-2 725 152 with reference to Figure 2, the anti-scratch layer is in contact with the wall of the mold. The thermoplastic injection is then made of a 3.5 mm thick polycarbonate layer marketed by the company GENERAL ELECTRIC under the reference GE 121 R. The rotary mold loader is activated over 180 °, so that the product of the injection Polycarbonate is located on a second impregnation. A copolymer of Styrene / ethylene / butylene / styrene modified hardness 75 Shore A, to form an overmolded profile over the entire periphery of the polycarbonate sheet. It is verified after the first injection, a perfect adhesion of the polycarbonate of the soul to the the outer layer. It is limited to a surface located inside the peripheral band intended to be coated by the encapsulated addition formed during the second injection. A slot in the bottom of the first shape of the mold allows, before the first injection, correctly locate the outer layer. At the end of the second injection, an excellent adhesion of the encapsulated addition on the polycarbonate core is observed.

^ M-agMM¡aBa¡HW '^ *' • l "'EXAMPLE 2 The operating mode of Example 1 is reproduced with a film of 325 μm thickness of the same standard polycarbonate provided, on one side, with an anti-scratch coating commercialized by the Society GENERAL ELECTRIC under the reference HP 92. A serigraph is made on the perimeter by means of epoxy based ink. The film is cut following the serigraphy. Its dimensions are such that it lies backwards in relation to the edges of the soul subsequently injected, as specified above. The film is placed in the mold cavity. The injection of the polycarbonate core is then carried out, and after the peripheral addition according to operations identical to those of Example 1. The final product has a transparency and an optical quality which are widely sufficient for an application as a crystal. The process of the invention presents the advantages inherent to the injection technique. The encapsulated addition does not necessarily have the entire periphery of the core. The excellent adhesion of the encapsulated addition on the polycarbonate core, already mentioned in Example 1, corresponds to a 90 ° peel force of the order of 100 N / cm, with a cohesive rupture in the encapsulation material (i.e. This is broken in the thickness of the tongue used in the peel test.In comparison with a normal thermoplastic elastomer such as propylene or ethylene / propylene / diene monomer copolymer (EPDM), the adhesion on primed glass corresponds to a 90 ° detachment force of 30-40 N / cm, but it is almost nil on plastic material. On the other hand, the method of the invention does not exclude forming the core with a peripheral ring to increase the rigidity, or with a relief and / or extensions such as ribs, profiles, tongues or ears, and / or dispose within the plastic material one or several inserts, particularly metallic. This arrangement is particularly useful for gripping or fixing the product of the invention, as well as for the final assembly to which it is intended, such as in an automobile vehicle body compartment. In the latter case, the formation of adapted peripheral profiles allows the assembly of the product to be considered on the inside of the vehicle, that is to say on the cab. The bead of adhesive ^ ¡^ ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^ is then arranged under the edge of the body opening, and is not exposed to sunlight. The protection of the bead of adhesive by a varnish formed on the periphery of the inner face of the sheet naturally becomes superfluous. The appendages formed in the periphery of the product, in the course of their injection can be conserved, or cut in their entirety or in part according to their use. A polishing can be provided after such a cut. A peripheral profiling of symmetrical geometry in relation to the plane of the product may be appropriate, for example in the case of transparent lateral surfaces of transport vehicles, one or the other part of the profiling can be cut later, depending on whether it is the right or left transparent element. . On the other hand, eventual inserts can be attached to the incorporation in the product of particular functions, such as a light reflection of headlights in a rear window. The method of the invention is thus economical, easy and reliable, and allows the use of numerous combinations of constituents, without presenting the problem of its compatibility, particularly in the plane of its temperatures. -.mj. * # í tfí.t. * " ** application. In particular, the use of a rotating part mold allows to obtain plastic crystals equipped with an encapsulation, particularly elastomeric, with short manufacturing times and high yields, for a minimum investment in equipment and machines, while maintaining the required optical quality.

Claims (18)

1. CLAIMS 1. Product essentially flat and of plastic material, at least partially transparent and of which at least part of the outer surface is constituted by an addition of overmolded plastic material.
2. 2. Product according to claim 1, characterized in that at least part of the addition of plastic material is encapsulated in the periphery of the product.
3. 3. Product according to claim 2, characterized in that it has a core of plastic material, an outer layer comprising at least one film of plastic material that supports an anti-scratch layer, and disposed on at least one face of the core towards the rear with respect to the edges of this, inside the surface bounded by the encapsulated peripheral part of the addition of plastic material.
4. 4. Product according to claim 3, characterized in that the outer layer, of thickness at most equal to 500 μm, preferably comprised between 50 and 300 μm, it is constituted by one or more films of thermoformable plastic material, between which is interposed, or on which is deposited the at least one functional layer, at least one of these films can be deposited. On the other hand, it constitutes itself such a functional layer.
5. 5. Product according to claim 4, characterized in that the thermoformable plastic material is selected from polycarbonate, polypropylene, poly (methyl methacrylate), ethylene / vinyl acetate copolymer, poly (ethylene terephthalate), polyurethane, polyvinyl butyral, and cycloolefin copolymer
6. 6. Product according to claims 3 to 5, characterized in that the outer layer comprises the hydrophobic / oleophobic function 20 incorporated in the anti-scratch layer, or grafted onto it or even coating it with interposition of a plastic film supporting the hydrophobic / oleophobic layer. ^^^ M
7. 7. Product according to claims 3 to 6, characterized in that the outer layer comprises, above all or part of its surface, a decoration and / or masking layer, preferably located directly under the support film of the anti-scratch layer.
8. 8. Product according to claims 3 to 7, characterized in that the outer layer comprises one or more optically selective layers.
9. 9. Product according to claims 3 to 8, characterized in that the outer layer comprises a stack of antireflective layers.
10. 10. Product according to claims 3 to 9, characterized in that the outer layer comprises an electrically conductive network.
11. 11. Product according to claims 3 to 10, characterized in that the core is constituted by a thermoplastic material such as polycarbonate, poly (methyl methacrylate), ethylene / vinyl acetate copolymer, poly (ethylene terephthalate), polyurethane, copolymer cycloolefinic, or of an ionomeric resin, or of a thermosetting or thermotransformable material of the type of polyolurethane, unsaturated polyester, ethylene / vinyl acetate copolymer, or even of an association of various thicknesses of the same or of various plastic materials.
12. 12. Product according to claims 2 to 11, characterized in that the encapsulated peripheral part of the addition of plastic material is constituted by one or more elastomeric materials, and in particular, thermoplastics.
13. 13. Method of manufacturing a product according to claims 1 to 12, characterized in that it comprises the injection of a first, and after at least a second plastic material in a single mode.
14. 14. Process according to claim 13, comprising a transfer operation by rotation of the product of the injection of the first plastic material, a first impregnation where the injection of the first plastic material has taken place, in a second impregnation that serves for the subsequent injection of the second plastic material.
15. 15. Process for manufacturing a product according to claims 1 to 12, characterized in that it comprises the injection into a first mold of a first plastic material, then the transfer of the product of this injection to a second mold, in which a second mold is injected. plastic material.
16. 16. Process for manufacturing a product according to claims 13 to 15, in which one or two outer layers, possibly previously thermoformed, are maintained at the bottom of the mold by any appropriate means, particularly by suction and / or blowing and / or electrostatic effect, before the injection of the first plastic material.
17. 17. Method of manufacturing a product according to claims 13 to 15, comprising an initial operation of forming an electrically conductive network by metal screen printing.
18. 18. Application of the product according to any of claims 1 to 12 as glass for transport vehicles or buildings.