FR2803790A1 - Production of glass material for vehicle headlights or rear lights, by forming two thin sheets of plastic, applying film applied to face(s) of sheet(s) and injecting material between assembled sheets - Google Patents

Abstract

Production of a glass material includes forming two thin sheets of plastic one or both of which have a film applied to one of their faces. The sheets are brought together in a mold and material is injected between them. When used in a vehicle light the film may be an external protective film, an internal anti-condensation film. The film may also be a colored or decorated film produced by silk screen printing, painting, hot marking and during molding contacts the injected material. The thin sheets are cut to size before entering the mold.

Description

 METHOD FOR MANUFACTURING PLASTIC ICE OF MOTOR VEHICLE PROJECTOR AND ICE PRODUCED THEREBY The invention relates to the field of the manufacture of plastic windows, including headlamps or rear lights of motor vehicles.

The substitution of glass by a transparent plastic for the manufacture of headlamps or motor vehicle lights is becoming more and more important because it allows - savings in weight (around 50%), - possibilities of shape that glass would not allow to consider at competitive costs, - increased resistance to small shocks, etc.

The physicochemical and mechanical characteristics of the plastics used for the manufacture of motor vehicle glass need to protect the ice on the outer face of the headlamp against, in particular, mechanical aggression which, by untimely diffusion and refraction of the light, may make the dazzling light beam; - ultraviolet radiation which causes its yellowing <B>; </ B> - chemical agents and surfactant liquids that can cause its whitening or crack the ice by release of internal stresses.

Plastic ice-making processes are already known comprising the step of applying, by known techniques, a protective lacquer film on the outer face of the molded ice, the application of this wet protective varnish. spray gun (automatic, HVLP, etc.), the electrostatic bowl, scrolling ice under a curtain of varnish (so-called flow coating process), etc., the windows being immobile or moving past the application means, itself mounted on an automaton or robot. The application of this coating can also be done by the dry method, for example, by screen printing, by vacuum deposition, etc.

The varnish application step is generally followed by a step of evaporating the solvents, then curing the varnish, by the action of heat or ultraviolet radiation, depending on the chemical nature of the varnish applied. The ice undergo these stages of varnishing and polymerization on driven or fixed positions of a conveyor generally chain.

These known plastic ice-making processes, including a step of applying a protective film or others, however, have disadvantages. First of all, the film deposition facilities on the ice occupy a lot of space, because it is necessary to have a sufficient interval between two windows on the conveyor.

In addition, when it is desired to deposit a film of varnish, the varnishing and polymerization steps require an air treatment and a perfect control over time of many parameters, difficult to control (constant temperature and hygrometry, level of cleanliness). , etc.). This air treatment is therefore complex and expensive, because of the large volume or the film application facilities. In addition, these varnishing and polymerization steps are performed off-stream, which requires handling and costs, and causes additional scrap. Added to this is the fact that wet processes are sources of significant pollution (emission of volatile organic compounds).

If, in addition, it is desired to treat the face of the ice opposite that which has received a protective film, for example to make the condensation not visible on the internal face of the windows, it is necessary to use complex masking systems to avoid any pollution of the face already treated.

The object of the invention is to overcome the aforementioned drawbacks and to propose a method for manufacturing plastic ice creams which, in particular, can be implemented without the problems of size and the corollary problems of air treatment or aforementioned masking.

This object is achieved according to the invention by means of a method for producing a plastic ice-cream for a motor vehicle lighting device, characterized in that it comprises the steps consisting in: - shaping two thin sheets of plastic material, at least one of which has been previously coated with a film on at least one of its faces, - placing each of the sheets in a part of a mold, - and molding the rest of the ice, by injection between the two leaves.

Preferred but non-limiting aspects of the method according to the invention are the following: a film constituting a protective coating is deposited on the external face of the sheet intended to be in contact with the external environment of the lighting device, prior to the formatting of this sheet; advantageously this protective coating is selected from the following families of organic compounds: polyurethanes, silicones, acrylics, or associates compounds belonging to several of these families; - A film constituting a decorative film, or coloring of the light, is deposited on the face of the sheet intended to come into contact with the injected material prior to the shaping of this sheet; advantageously the decorative film, or coloring the light, is produced by screen printing, painting, hot stamping, or obtained by tinting a thin sheet in the mass; - A film constituting an anti-condensation coating is deposited on the face of the sheet, intended to form the inner face of the ice, prior to the shaping of this sheet; advantageously, the anti-condensation coating is chosen from hydrophilic product families, so that the surface energy of this coating is greater than the surface tension of the water; at least one of the sheets is made of a material chosen from the list comprising polycarbonate, polymethylmethacrylate (PMMA), polymethacrylate imide (PMMI) and polyetherimide; the plastics material of each thin sheet and the plastic injection material are identical; the step of shaping at least one of the thin sheets is carried out by softening a flat thin sheet and pressing it against the cavity of the mold; the step of shaping at least one of the thin sheets is carried out by preforming before being placed in the mold; it further comprises a step of cutting at least one of the thin sheets in an extruded raw thin sheet, after shaping this sheet and before placing it in the mold; the step of coating one of the faces of at least one thin sheet with a film is performed before the cutting step.

According to another aspect, the invention relates to an ice cream obtained by this method.

Other aspects, objects and advantages of the invention will appear better on reading the detailed description which follows.

The invention will also be better understood with reference to the drawings in which: - Figure 1 shows schematically in section, the structure of a motor vehicle headlamp glass made by the method according to the invention; FIG. 2 represents a flow chart of an embodiment of a method according to the present invention.

A partial schematic section of a projector lens made by a process according to the present invention is shown in FIG.

This ice cream has an outer face 1 and an inner face 2.

The outer face 1, particularly subject to mechanical, physicochemical, etc. attacks. , is protected from these various attacks by an outer sheet 3. The outer sheet 3 is intended to cover the outer face of the ice. This outer sheet 3 is covered on its outer face, that is to say that intended to be in contact with the external environment to the lighting device, a protective coating 4, and on its opposite side of a decorative film 5, or coloring light.

The protective coating 4 preferably contains - an organic resin crosslinkable by heat or ultraviolet radiation; a catalyst system corresponding to this resin; - anti-ultraviolet protection agents; agents which improve the wetting of the outer sheet 3 by the organic resin, as well as the tension of the protective coating 4 on the outer sheet 3 after crosslinking.

The organic resin constituting the protective coating 4 is preferably chosen from one of the families used for the protection of plastic ice and known to those skilled in the art. These families are typically polyurethanes, silicones, acrylics, or others, as well as the combination of these resins together.

The decorative film 5, or coloring the light is, for example, screen-printed, painted, hot-stamped, or obtained by dyeing the outer sheet 3 in the mass.

The inner face 2 comprises an anti-condensation complex. This anti-condensation complex consists of an internal sheet fi covered on the face intended to be directed towards the interior of the lighting device, with an anti-condensation coating 8. This anti-condensation coating 8 is advantageously chosen from hydrophilic product families, so that the surface energy of this coating is greater than the surface tension of the water.

According to the method according to the present invention, a thick layer 9 of plastic material is injection molded between the outer 3 and inner 6 sheets. Preferentially, the outer 3 and inner 6 sheets and the thick layer 9 are made of a plastics material. identical.

Thus, from the outer face 1 to the inner face 2 the ice made by a method according to the invention is formed by the juxtaposition of the protective coating 4, the outer sheet 3, the decoration film 5, or coloring the light, the thick layer 9, the inner sheet 6 and the anti-condensation coating 8. It will be observed here that during the injection of the plastic material of the thick layer 9, as will be described later , the heat provided by the thick layer 9 causes a superficial softening of the outer or outer faces 3 and 3, and exposed thereto, and consequently, a fusion between these parts 3, 6 and 9, to form one and the same body with no marked transition, and therefore no optical defect at the meeting between these parts 3, 6 and 9.

Preferably, the plastics material of the outer sheet 3, the inner sheet 6 and the thick layer 9 is polycarbonate or PMMA of optical quality, for example crystal polycarbonate.

Preferably, the outer sheet 3 has a thickness of 0.05 to 0.5 mm. Advantageously, at least one of the thin sheets 3, 6 has a thickness of between 0.2 and 0.4 mm.

We will now describe in detail a preferred embodiment of the method of manufacturing such an ice according to the invention. According to this mode of implementation, illustrated in FIG. 2, the method comprises - an extrusion step 100 of the outer sheet 3; it will be noted that this step which implements a conventional tooling per se, may be carried out by subcontracting independently of the following steps; a deposition step 200 of the protective coating 4 on the outer sheet 3; a deposition step 300 of the decorating film 5, or of staining the light on the face of the outer sheet 3 opposite to that having received the protective coating 4; - A preforming step 400 of the outer sheet 3 coated with the protective coating 4 and the decorative film 5, or coloring the light; to give it the shape of the outer face 1 of the ice; - A cutting step 500 of the outer sheet 3 preformed to form an insert; -. an extrusion step 600 of the inner sheet 6; a deposition step 700 of an anti-condensation coating 8 on one of the faces of the inner sheet 6; - A preforming step 800 of the inner sheet 6 coated with the anti-condensation coating 8, to give it the shape of the inner face 2 of the ice; - A cutting step 900 of the inner sheet 6 to form an insert; - A step 1000 of placing the outer sheet 3 in a mold 10, the bag side 12 thereof, that is to say the side corresponding to the outer face 1 of the ice; - A step 1100 of placing the inner sheet 6 in the mold 10, the punch side 14, that is to say, corresponding to the inner face of the ice 1; a step 1200 of injection into the mold of the plastic material intended to form the thick layer 9 and a step 1300 of ejection of the ice from the mold 10.

The deposition step 200 of the protective coating 4 on the outer sheet 3 is carried out wet, for example by roll coating, spray coating, flow coating, coil coating, or deposition. vacuum, etc.

If necessary, this depositing step is accompanied by one or more deposition operations in specific areas of the sheet 3, a colored deposit (for example of amber color to give its regulatory color to the signaling beam of the flashing function), an opaque painting of decor, etc. The deposition step 300 of the decoration film 5, or of the light coloring, can be performed by screen printing, heliography or vacuum deposition, on a crystal film of optical quality or obtained by dyeing the outer sheet 3 or inner sheet 6 in the mass, the preforming steps 400, 800 or outer 3 and inner 6 sheets can be carried out under high pressure or by thermoforming.

During the steps of setting up 1000, 1100 of the outer 3 and inner 6 sheets in the mold 10, the outer 3 and inner 6 sheets are held in the mold 10, either by electrostatic charging, or by mechanical retention, or even by suction in the mold 10.

According to a variant of this method, the preforming steps 400, 800 may be implemented just after the extrusion 100, 600 of the outer 3 and inner 6 sheets separately from the rest of the process.

The method according to the invention may comprise many other variants. In particular, the cutting steps 500, 900 may precede the preforming steps 400, 800 and / or the depositing step 200, 300, 700 of the protective coating 4, the anti-condensation coating 8, or the decorative film 5. , or staining of light.

According to yet another variant, the preforming steps 400, 800 may take place during the closing of the mold 10, the outer and inner leaves 6 having been preheated before their glass transition temperatures (T9) by thermal heating, infrared radiation or induction. The outer 3 and inner 6 leaves, initially flat or having received a first degree of preforming, are then definitively set to the shape of the mold cavity, directly by the pressure exerted by the plastic material intended to form the thick layer 9, at the during his injection. The cutting steps 500, 900 of the outer 3 and inner 6 sheets can be performed by laser or by robotic cutting or punch-die tool.

According to yet another variant, the steps of setting up 1000 and 1100 of the outer 3 and inner 6 sheets are reversed. According to yet another variant, is deposited on at least one of the faces of at least one of the outer thin sheet 3 and inner 6, an infrared protective coating. Advantageously, the infrared protective coating is on the inner thin sheet 6, in order to limit the heating of the lighting device according to the invention.

According to yet another variant, only a protective coating 4 is deposited on the external thin sheet 3 on its outer face, and a decorative film 5 is deposited on the inner thin sheet 6, or a coloring film on the outer thin sheet 6. light, on the face of the thin sheet 6 intended to come into contact with the injected material, and an anti-condensation coating 8 on the face of the sheet 6, intended to be directed towards the inside of the lighting device.

According to yet another variant, is deposited on the outer thin sheet 3, only a decorative film 5, or staining of light, on the face of the thin sheet 6 intended to come into contact with the injected material.

Claims (14)

<B> CLAIMS </ B> 1. A method of manufacturing a plastic ice for a motor vehicle lighting device, characterized in that it comprises the steps of - shaping (400, 800) two thin sheets (3, 6) of plastic material, at least one of which has been previously coated with a film (4, 8) on at least one of its faces, - placing (1000, 1100) each of the sheets (3, 6) in a mold (10), - and mold (1200) the rest of the ice, by injection between the two sheets <B> (3,6). </ B> 2. Method according to claim 1, characterized in that a film constituting a protective coating (4) is deposited on the external face of the sheet (3) intended to be in contact with the environment external to the device. lighting, prior to the shaping of this sheet (3). 3. Method according to claim 2, characterized in that the protective coating (4) is selected from the following families of organic compounds: polyurethanes, silicones, acrylics, or associates compounds belonging to several of these families. 4. Method according to one of the preceding claims, characterized in that a film is deposited constituting a decorative film (5), or coloring of light, on the face of the sheet (6) intended for come into contact with the injected material, prior to the shaping of this sheet (6). 5. Method according to claim 4, characterized in that the decorative film (5), or coloring of the light, is produced by screen printing, painting, or hot stamping or obtained by dyeing a thin sheet (3, 6) in the mass. 6. Method according to one of the preceding claims, characterized in that a film forming an anti-condensation coating (8) is deposited on the face of the sheet (6) intended to be directed towards the inside of the lighting device, prior to the shaping of this sheet (6). 7. Method according to claim 6, characterized in that the anti-condensation coating (8) is selected from the hydrophilic product families, so that the surface energy of the coating is greater than the surface tension of the water. 8. Method according to one of the preceding claims, characterized in that at least one of the thin sheets (3, 6) consists of a material selected from the list comprising polycarbonate, polymethyl methacrylate, polymethacrylate imide and polyetherimide. 9. Method according to one of the preceding claims, characterized in that the plastic material of each thin sheet (3, 6) and the plastic injection material (9) are identical and in particular crystal polycarbonate. 10. Method according to one of the preceding claims, characterized in that the shaping step of at least one of the thin sheets (3, 6) is performed by softening a flat thin sheet (3, 6) and pressing it against the mold cavity (10). 11. Method according to one of claims 1 and 9, characterized in that the shaping step of at least one of the thin sheets (3, 6) is performed by preforming (400, 800) before its placement in the mold. 12. Method according to one of the preceding claims, characterized in that it further comprises a step of cutting (500, 900) at least one of the thin sheets (3, 6) in an extruded raw thin sheet, after shaping (400, 800) this sheet (3, 6) and before placing it in the mold (10). 13. The method of claim 12, characterized in that the step of coating one of the faces of at least one thin sheet (3, 6) with a film is performed before the cutting step (500). , 900). 14. Method according to one of the preceding claims, characterized in that at least one of the thin sheets (3, 6) has a thickness of between 0.2 and 0.4 mm.