MXPA98004776A - Thermoplastic compositions based on transparent thermoplastic copolymers containing useful polyamide particles for molded articles spreading the - Google Patents

Abstract

The thermoplastic invention for shaped light diffusing articles comprises a transparent thermoplastic polymer, namely a methacrylic copolymer and polyamide particles having an average dimension of 0.4 to 200 hm. The application to luminous alization devices comprises a plate obtained from the composition

Description

THERMOPLASTIC THERMOPLASTIC COMPOSITIONS BASED ON THERMOPLASTIC TRANSPARENT COPOLYMERS CONTAIN USEFUL POLYAMIDE PARTICLES FOR MOLDED ITEMS THAT SPREAD THE LIGHT FIELD OF THE INVENTION The invention relates to a thermoplastic composition based on transparent thermoplastic copolymer containing polyamide particles usable for shaped articles, in particular plates that play the role of light guide and light diffuser. These plates are particularly useful for light display systems.

BACKGROUND OF THE INVENTION The luminous visualization systems are known and comprise, in general, a unit mounted in a suitable frame, comprised of a plate or panel of transparent plastic material containing particles of material that can diffuse light. The light source, in general fluorescent tubes, can be found in the vicinity of the face of a panel of thermoplastic material and, on the opposite side, directly transmitted light and that diffused by the known particles in the panel are observed.

P1383 / 98MX In this case, the panels of thermoplastic material contain a large amount of diffuser particles to make them sufficiently opaque to mask the light source. The panels are integrated in a box that contains the fluorescent tubes. These tubes must be sufficient in number in order to ensure a good distribution of light intensity. This box has the drawback of being thick and this device consumes a lot of energy. The light source can also be located in the vicinity of one or some edges of the panel in order to illuminate it by the edge (or edge). The panels work, therefore, as light guides. This is reflected and then diffused by the diffusing particles contained in the panel and a part of the diffused light is observed through one or two faces of the panel. If the panel contains a large amount of diffuser particles, the optical path followed by the light is short and a part of the surface will not light up or be poorly illuminated. If the panel contains few diffusing particles, the intensity of the diffused light is weak. The diffused luminous intensity decreases as a function of the elongation of the light source. It is then sought compositions of transparent thermoplastic material, moldable articles P1383 / 98MX shaped, in particular in the form of usable plates, for example, as panels of luminous display devices which, by containing a minimum of diffusing particles, allow a maximum and uniform diffused luminous intensity on all the surface of the shaped article.

DETAILED DESCRIPTION OF THE INVENTION The thermoplastic composition according to the invention, for a shaped article, diffuser of light, comprises a transparent thermoplastic material and in relation to the total composition, from 20 ppm to 100 ppm of polyamide particles of a size particle mean 0.4 μm to 200 μm. The thermoplastic material may, for example, be a copolymer of methacrylate, of polycarbonate, of polystyrene, of polyterephthalate of ethylene, copolymers constituted by polyethylene terephthalate modified by a glycol, for example diethylene glycol, butanediol, hexanediol and 1,4-cyclohexane dimethanol or mixtures of polyethylene terephthalate and copolyesters. The methacrylic thermoplastic copolymer can, in particular, consist of an homopolymer of alkyl methacrylate or of a copolymer derived from acryl methacrylate and of at least one monomer with P1383 / 98 X ethylenic unsaturations copolymerizable with alkyl methacrylate. As the alkyl methacrylate, mention may be made in particular of compounds in which the alkyl group has from 1 to 8 carbon atoms, for example methyl, ethyl, propyl, isopropyl and butyl methacrylate. A particularly preferred monomer is methyl methacrylate. The methacrylic thermoplastic copolymer preferably comprises from 70 to 100% of main monomer, the alkyl methacrylate, and from 0 to 30% by weight of ethylenically unsaturated monomers copolymerizable with the alkyl methacrylate. This monomer or monomers with unsaturation or ethylenic unsaturations are selected, for example, from C 1 -Cg alkyl acrylates, styrene, substituted styrenes, acrylonitrile, methacrylonitrile, C 1 Cg alkyl methacrylates, other than the main monomer, acrylates and methacrylates of hydroxyalkyl, acrylates and alkoxy alkyl or aryloxy alkyl methacrylates in which the alkyl group has from 1 to 4 carbon atoms, acrylamide, methacrylamide, acrylic acid, methacrylic acid, maleimides and the alkylene glycol dimethacrylates, in which the group Alkylene has from 1 to 4 carbon atoms. The methacrylic copolymers can be obtained by P1383 / 98MX all known processes, for example by suspension or bulk polymerization. The composition according to the invention comprises polyamide particles which advantageously have an average particle size between 0.4 and 100 μm, preferably between 0.4 to 50 μm. Medium-sized particles of 1 to 15 μm are particularly suitable. Preferably, the polyamide particles have a distribution granulometric range, ie more than about 90% have a particle size between 2.5 and 10 μm. The composition contains, in addition to 100 to 200 ppm, polyamide particles. As polyamides, those obtained from lactams, such as, for example, e-caprolactam, enantolactam, undecanolactam, laurilacta, can be used from amino acids whose carbon chain has a number of carbon atoms comprised between 4 and 20 aminocaproic acids , amino-7-heptanoic, amino-11-undecanoic, amino-12-dodecanoic. The condensation products of diamines such as hexamethylenediamine, dodecanemethylenediamine, metaxylylenediamine, bis- (p-aminociclohexyl) methane, trimethylhexamethylenediamine, etc. can also be used. , with dicarboxylic acids such as isophthalic, terephthalic, adipic, suberic acids, P1383 / 98MX acelaic, sebacic, dodecanedioic, dodecanedicarboxylic; there may be mentioned, as examples, polyamides 6-6; 6-9; 6-12; 9-6 which are condensation products of hexamethylenediamine with adipic acid, azelaic acid, sebacic acid, 1,2-dodecanedioic acid or the reaction product of nonamethylidene diamine with adipic acid. Mixtures of all these monomers can also be used which leads to copolyamides. Among these polyamides, mention may be made in particular of polyamide 6 obtained by the polymerization of e-caprolactam, polyamide 11 obtained by polycondensation of amino-11-undecanoic acid, polyamide 12 obtained by polycondensation of amino-12-dodecanoic acid or dodecanolactam. By "polyamide" are meant also polyetherramides and polyetheresteramides. The polyamides obtained in the form of granules can be transformed into powder of suitable size, by known techniques, for example by grinding the granules, hot dissolving in solvents or precipitation by cooling. It is also possible to obtain these polyamides directly in the form of a powder by anionic polymerization of the monomer (s), as already described, for example in Patents Nos.

P1383 / 98MX EP-B1-192515 or EP-B1-303530. The polyamide powder obtained by the process described in EP-B1-303530, particularly useful in the invention, is formed of porous elementary particles of substantially spheroidal shape, with an average diameter comprised between 1 and 20 μm, in particular between 2 and 10 μm . Particularly suitable polyamides with those obtained from Elf Atochem S.A. with the trade names Rilsan and Orgasol. "The composition according to the invention can contain typical additives such as dyes, fillers etc. The composition can be obtained by mixtures of methacrylic polymers and polyamides in all suitable devices, for example in a mixer of the type Brabender, a single screw or twin screw extruder, etc. The shaped light diffusers that can be manufactured from the thermoplastic composition described above, can be obtained by various known molding processes, in particular, by extrusion, injection, compression In this way, products in the form of plates or molded products are obtained in various ways.The formed articles can also be obtained directly in the form of plates by P1383 / 98MX d mass polymerization of a mixture of methacrylic monomers and optionally of its prepolymer, in the presence of polyamide and other possible additives, in a mold formed by two glass plates (casting process). known free radical initiators, for example diazo compounds such as azo-bis-isobutyronitrile (AIBN), peroxides such as benzoyl peroxide. The polymerization is carried out in general, in the presence of a chain transfer agent such as monocyclic unsaturated terpenes and mono-unsaturated bicyclic terpenes, such as terpinolene, mercaptans such as tert-dodecyl mercaptan. Agents that promote demolding of the plates can be added, for example stearic acid, sodium dioctyl sulfosuccinate. The shaped articles according to the invention and, in particular, the plates can also be made of a transparent thermoplastic material, like those formed above, comprising a concentration of polyamide particles that varies throughout the thickness of the article, the concentration more Strong is located in an area near the diffusion surface. This difference in concentration in the thickness of the article P1383 / 98MX can be progressive and occurs in the form of the concentration gradient. This embodiment makes it possible to increase the transmission of light in the area of the article of average concentration of polyamide particles and, subsequently, a greater uniformity of the intensity of the light diffused throughout the surface of the article, in particular in the elongated areas of the light source. The plates obtained from the compositions of the invention are mainly used to manufacture panels for advertising light systems. In the cases where the panels are illuminated by the edge or edge, a thickness of at least about 6 mm is advantageous. Diffuser panels with a thickness less than 6 mm are therefore useful for particular applications. When the panels are illuminated on one side, the minimum thickness can be larger, for example from 8 to 15 mm. In this way it is possible to manufacture panels for the light visualization system, comprising, for example, a support of a transparent thermoplastic material, for example polymethyl methacrylate, polystyrene, polycarbonate, polyethylene terephthalate or copolyesters constituted by modified polyethylene terephthalate. a glycol, and a diffusing layer formed from the P1383 / 98MX thermoplastic diffuser composition described above. This product can be obtained by all suitable methods, for example by co-extrusion, lamination. One embodiment of the light display system comprises a panel constituted by a plate from a thermoplastic composition according to the invention illustrated in Figure 1. The panel (1) is associated with at least one medium forming the source luminous (2), such as a fluorescent tube mounted to illuminate the panel by its edge or edge. To improve the uniformity of the diffused light, two light sources (2) are placed following two opposite sides (edges) of the panel. Advantageously, the edges (3) that look at the light sources are polished previously to avoid reflection of the light emitted by the source. The edges do not face the light sources (not shown in Figure 1) that carry a reflective layer of light, for example a metallic film such as an aluminum film, carried for example by an adhesive backing as the product of the brand 3M Scotch type 850, or the metallic layer is deposited, for example, by sputtering, possibly after surface pre-treatment, as described in P1383 / 98MX EP-A-0 650772. The face (A) of the panel through which the diffused light is observed can carry a light diffusing film or plate (4) having a transmission coefficient depending on the desired effect to further improve the uniformity of the diffused light. The transmission coefficient of this film or this plate is preferably greater than or equal to about 50%. This film, or this plate, can be constituted by all the suitable material, for example, it can be a polymer such as the methyl polymethacrylate treated to obtain the desired transmission (for example Altuglas® Ref. 101.27019 obtained from ATOHAAS Eurepe) or a paper support that has a suitable light transmission or in the advertisement that will be illuminated. In order to obtain a better reflection of the light, before diffusion, the face (B) opposite that by which the diffused light is observed, advantageously carries a film or an opaque plate (5) formed by all the suitable material, example by methyl polymethacrylate treated to have a weak transmission (for example Altuglas® Ref. 101.47005) a white vinyl chloride polymer, a white polyester or polyethylene. These films or diffuser plates (4) and opaque P1383 / 98MX (5) can have a thickness that varies according to the desired use. These different described elements are assembled without sticking or they can be adhered to the panels by any suitable means. According to an advantageous modality that allows to improve the intensity of the diffused light, the films (4) and / or (5) placed respectively on the faces (A) and (B) are in the form of parallel adhesive bands of a length of a few millimeters to a few centimeters, for example of the order of 0.5 to 20 mm, separated regularly or not from each other by a distance of a few millimeters to a few centimeters (for example from 0.5 to 20 mm). The distance that separates these bands can be equal, higher or lower than the length of the bands. In particular, the distance separating the bands can be narrower as the light source is lengthened. In case the light source consists of fluorescent tubes, the parallel bands are parallel to each other and between the tubes. Preferably, only the face (B) carries a film (5) in the form of parallel bands. These bands adhere to the surface of the panel by any suitable means. In case the film (5) on the face (B) is in the form of bands, a film or a plate (5 ') is P1383 / 98 X placed on this film (5) to avoid light losses. In Figure 1, the element 6 represents, by way of example, a possible information support. The following non-limiting examples illustrate the invention. In these examples, the moldable thermoplastic material consists of polymethyl methacrylate (PMMA). It is prepared from useful panels in the luminous display devices as indicated in the examples. The intensity of diffused light is measured using an assembly as shown in Figure 2. The evaluation of the diffused light intensity is made with a LAP luxmeter whose cell (13) is placed on the surface of the panel at a distance of 5 cm and 50 cm from the light source (11). This evaluation allows to finish the uniformity of the luminous intensity in the unit of the surface of the panel.

EXAMPLES 1 AND 2 In each of the examples a light diffusing panel is prepared by the bulk polymerization process. A methyl methacrylate prepolymer is prepared by adding 20 ppm by weight of 2,2-azobis-isobutyronitrile catalyst to the methyl methacrylate monomer. The mixture is heated to 90 ° C until a conversion ratio of the order of 7% is obtained.

P1383 / 98MX This prepolymer is cooled, and then the quantity (250 ppm) of catalyst necessary for the polymerization of all the monomer, 55 ppm of chain transfer agent (terpinolene) and 150 ppm of polyamide powder ORGASOL 2001 is added. ® (polyamide 12) for example 1 and ORGAZOL 3502® (POLYAMIDE 6,12) for example 2, obtained from Elf Atochem SA, with an average particle size of 5 μm and 15 μm. 100 ppm of classical mold release agent, sodium dioctyl sulfosuccinate, is also added. The mold is formed of two glass plates of dimensions (1000 x 1000 x 8 mm), separated by its perimeter by a joint of blown polyvinyl chloride (PVC), whose diameter determines the thickness of the final plate (8 mm). The two ends of the joint are kept separate to allow the introduction of the polymerizable composition. These glass plates are fastened with metal clips. The composition is subjected to vacuum for 30 minutes to remove the air, then it is introduced into the mold, with the help of a funnel placed between the two ends of the PVC gasket, and the mold is closed by contacting the two ends. The mold is placed in a ventilated oven to polymerize the methyl methacrylate. The temperature cycle consists of heating the mold to 55 ° C during P1383 / 98MX 600 minutes, then at 120 ° C for 2 hours in order to ensure a maximum conversion of at least 99%. A plate with a thickness of 8 mm is obtained. This plate is tested as indicated above, such as panel 7 in a mounting as shown in Figure 2. The face (A) of the panel carries a diffuser plate (12) transmission 50% with a thickness of 3 mm in White Altuglas®, opal, Ref. 101.27019. This plate simulates an advertisement that will be illuminated by the diffused light. The panel (7) of PMMA carries on the face (B) an opaque film (8) of 150 μm in thickness and constituted by the white polyvinyl chloride. The edge (9), which is not oriented towards the light source, bears a reflective aluminum film. The edge (10) of the panel facing the light source (11) placed 1 mm from the surface of the edge (10) is constituted by a fluorescent tube (B) Mazda Fluor Symphonie Harmonía 950 (36W for a luminous flux of 2850 lumens). With the polyamide Orgasol 2001 (example 1): at 5 cm from the light source, the luminous intensity measured by the luxometer is 180 lux. At 50 cm from the light source, the luminous intensity is 170 lux. With polyamide Orgasol 3502 (example 2): a 5 P1383 / 98MX cm, the light intensity is 160 lux; at 50 cm it is 150 lux. It can be seen that the luminous intensity varies little between the part of the panel located before the light source and that located at the end of the panel, which means that the luminous intensity is uniform over the entire surface of the panel. It is also noted that the panels according to the invention have a slightly bluish, aesthetically pleasing white tint. This shade is evaluated by the measurements made with the colorquest integration Colorquest spectrum spectrum, model 1200 M50 of Hunterlab, which allows to determine the three parameters L *, a * and b * defined by the CIÉ committee (International Lighting Committee). This allows defining a color in relation to white, gray and black patterns. In particular, for the product containing Orgasol 2001 orgamide particles, the above 3 parameters, measured on the light diffused by the panels in use condition, are respectively 2.2 + 1.4 and -12. 3a to 3d A PMMA plate is used as prepared in Examples 1 and 2. It contains 150 ppm of ORGASOL 2001 polyamide in powder form of average size of 5 μm.

P1383 / 98MX This plate has a dimension of 300 x 420 x 8 mm. It is used as a panel in a luminous display device such as that shown in Figure 2. Light source (11) is constituted by an FM fluorescent tube of the company OSRAM having a diameter of 7 mm and a length of 320 mm . The power consumed is 8 watts for a luminous flux of 500 lumen. The tube is placed 1 mm from the surface of the edge (10), along the large side. The unlighted edges are covered with a reflective adhesive strip, all the edges are polished. The face (A) of the panel has a diffuser plate (12) white opaline ALTUGLAS® Ref. 101-27019 with a thickness of 3 mm, which serves to simulate an advertisement. The face (B) opposite that by which the diffuse light is observed, has a coating constituted by an adhesive film (8) of opaque polyvinyl chloride, white, of a thickness of 80 μm, sold under the name Scotchcal Electrocut, white, by the company 3M (transmission = 12%). This film is presented continuously or in the form of bands parallel to each other. The face (B) of the panel, provided with the adhesive film continuously or in the form of parallel strips, also carries a white and opaque plate (8 ') of ALTUGLAS Ref. 101-47005, of a thickness of 3 mm . The intensity P1383 / 98MX luminous, diffused by the face (A) is measured as indicated above, with a LAP luxmeter whose cell is placed on the surface of the panel at different distances from the light source. Table 1 provides the light intensities diffused in the function of the distance towards the light source, observed with several panels according to the invention that carry or do not carry a white adhesive film. The white film is in continuous form or in the form of bands parallel to each other and to the fluorescent tube. The panels are as follows: panel (a) = panel without adhesive film, panel (b) = panel carrying a continuous adhesive film. panel (c) = panel carrying the adhesive film in the form of parallel strips with a width of 2 mm and separated by a distance of 3 mm. panel (d) = panel carrying the adhesive film which is in the form of bands parallel to each other, deposited as follows: - at a distance of 8 cm from the light source: adhesive strips 2 mm wide and separated by 8 mm.

P1383 / 98MX at a distance that is 8 cm to 17 cm from the light source: 2 mm band of widths separated by a distance of 3 mm. at a distance of 17 cm to 30 cm from the light source: adhesive film continuously.

TABLE 1 It can be seen that the panel (b) (continuous film) is brighter than the panel (a) (without adhesive film) but the intensity of the diffused light is not very homogeneous.

P1383 / 98MX With the plate (c), which carries the bands parallel to each other and to the fluorescent tube, the diffused luminous intensity is more homogeneous than that obtained with the plate (b). With the plate (d) a more homogeneous luminous intensity is observed than that obtained with the plate (c).

EXAMPLES 4a and 4b COMPARATIVE As a comparison, the diffused luminous intensity is measured as a function of the distance to the light source of the panels formed from Altuglas CN 100-10,000 (cast polymethyl methacrylate - PMMA - which does not contain polyamide particles) . These panels are mounted on a luminous display device such as those described in Examples 3b and 3c. In Example 4a, the plate or panel of Altuglas CN 100-10,000 carries a continuous adhesive film identical to that used in Example 3b. In Example 4b, the plate carries an adhesive film in the form of parallel bands identical to those used in Example 3c. The measurement of the light intensity diffused at a distance of 15 cm and 30 cm from the light source gives the following results: P1383 / 98MX TABLE 2 It can be seen that the plates containing the polyamide particles according to the invention have a higher diffused luminous intensity than that obtained with a PMMA plate which does not contain polyamide particles.

P1383 / 98MX

Claims (27)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS-1 is claimed as property. Thermoplastic composition for a shaped article light diffuser, with base of transparent thermoplastic material , characterized in that it contains, in relation to the total composition, from 20 ppm to 1000 ppm of polyamide particles of average size comprised between 0.4 μm and 200 μm. The composition according to claim 1, characterized in that the transparent thermoplastic material is a methacrylic copolymer, polycarbonate, polystyrene, polyethylene terephthalate or a copolyester consisting of polyethylene terephthalate modified by a glycol or a mixture of polyethylene terephthalate and copolyester . 3. The composition according to claim 2, characterized in that it comprises a methacrylic thermoplastic copolymer selected from alkyl polymethacrylates and copolymers of alkyl methacrylate and at least one monomer with unsaturation or ethylenic unsaturations copolymerizable with acryl methacrylate. 4. The composition according to claim 3, P1383 / 98MX characterized in that the thermoplastic copolymer comprises from 70 to 100% of the main monomer, the alkyl methacrylate, and from 0 to 30% by weight of the monomer or monomers with unsaturation or ethylenic unsaturations copolymerizable with the alkyl methacrylate. 5. The composition according to claim 4, characterized in that the monomers of ethylenic unsaturation are selected from the acrylates of styrene acrylate, substituted styrenes, acrylonitrile, methacrylonitrile, CI-CQ alkyl methacrylates, other than main monomer, acrylates and methacrylates. of C 1 -C 4 hydroxyalkyl, C 1 -C 4 alkoxyalkyl acrylates and methacrylates, or aryloxy C 1 -C 4 alkyl, acrylamide, methacrylamide, acrylic acid, methacrylic acid, maleimides and alkylene glycol dimethacrylate in which the alkylene group is 1 to 4 carbon atoms. 6. The composition according to claims 3 to 5, characterized in that the alkyl methacrylate is from 1 to 8 carbon atoms in the alkyl group. The composition according to claim 6, characterized in that the alkyl methacrylate is selected from the group consisting of methyl, ethyl, propyl, isopropyl and butyl methacrylate. 8. The composition according to claims 1 P1383 / 98MX to 7, characterized in that the polyamide particles have an average size comprised between 0.4 μm and 100 μm, preferably between 0.4 and 50 μm. 9. The composition according to claims 1 to 8, characterized in that from 100 to 200 ppm of polyamide particles. 10. The composition according to claims 1 to 9, characterized in that it comprises polyamide particles of narrow granulometric distribution. 11. The composition according to claims 1 to 10, characterized in that the polyamide is obtained from one or several lactams, from one or more amino acids or from mixtures of diamines and diacids or from the mixture of these monomers. 12. The composition according to claim 11, characterized in that the lactams are selected from e-caprolactam, enantslactam, undecanolactam, laurilactam. The composition according to claim 11, characterized in that the amino acids are selected from amino acids whose carbon chain contains from 4 to 20 carbon atoms, and preferably from aminocaproic, amino-7-heptanoic, amino-11-undecanoic acids, amino-12-dodecanoic. 14. The composition according to claim 11, P1383 / 98MX, characterized in that the polyamide derived from the polycondensation of hexamethylenediamine, dodecanethylene diamine, methoxylylenediamine, bis- (p-aminociclohexyl) methane and / or trimethylhexamethylenediamine, with one or more isophthalic, terephthalic, adipic, sub-surface, acelaic acids, sebacic, dodecanedioic, dodecanedicarboxylic 15. The composition according to claim 11, characterized in that the polyamide is selected from the group consisting of polyamide 6, obtained by the polymerization of e-caprolactam, polyamide 11 obtained by polycondensation of amino-11-undecanoic acid, polyamide 12 obtained by polycondensation of amino-12-dodecanoic acid or the dodecanolactam, the polyamide 6.12 obtained by polycondensation of hexamethylenediamine with 1,2-dodecanedioic acid. 16. Shaped article light diffuser formed from the composition according to one of claims 1 to 15, by extrusion molding, injection, compression or casting. 17. The article according to claim 16, formed in the form of plates. 18. The article according to claim 17, comprising a concentration of polyamide particles that varies throughout the thickness of the article, the concentration P1383 / 98MX greater is located in an area close to the diffusion surface. 19. The light diffuser shaped article comprising a support of transparent thermoplastic material and a layer of a composition according to one of claims 1 to 15. The article according to claim 19, wherein the support of transparent thermoplastic material it is selected from a methacrylate, from polycarbonate, polystyrene, from polyethylene terephthalate, or a copolyester consisting of polyethylene terephthalate modified by a glycol or a mixture of polyethylene terephthalate and copolyester. 21. The article according to one of claims 19 to 20, wherein they are obtained by coextrusion or lamination. 22. Luminous display system comprising a panel constituted by an article according to one of claims 16 to 21 and therefore a means that forms a light source. 23. System according to claim 22, comprising at least one medium forming an elongated light source, mounted to separate the panels by its edge or edge. 24. Light visualization system according to a P1383 / 98MX of claims 22 and 23, comprising a panel carrying a film or a diffuser plate of light on the surface through which the diffused light is observed. 25. The light visualization system according to one of claims 22 to 24, comprising a panel carrying a film or an opaque plate on the face opposite to that through which the diffused light is observed. 26. The light visualization system according to claim 24, wherein the light diffusing film and / or the opaque film are in the form of parallel adhesive strips, spaced in a regular or non-spaced manner. 27. The system according to claim 26, wherein the film is in the form of adhesive strips parallel to each other and between means forming the elongated light source (s) mounted to illuminate the panels by their edge or edge. P1383 / 98MX