CONTINUOUS PROCESS FOR MANUFACTURING THERMOSET DECORATIVE PANELS

Abstract: Continuous process for the manufacturing of thermoset panels (22) cured by ultraviolet radiation, and high quality panels obtained. Two layers of fiber reinforced resin (5, 11) are contacted with a decorative sheet (9) allowing the resin to impregnate the decorative sheet. The layers are passed through a lamination/pultrusion station (16, 19), an ultraviolet photopolymerization station (18), and a cutting station (21). The surface of the fiber reinforced resin layers may be provided with a desired texture in the lamination/pultrusion station.

Description: DESCRIPTION CONTINUOUS PROCESS FOR MANUFACTURING THERMOSET DECORATIVE PANELS This invention relates to a continuous process for manufacturing of panels and similar products, cured by ultraviolet radiation, and obtained products, used in visual communication, such as: decoration elements, publicity, signs, backlights, didactic material, building elements, transport and other similar applications, and that it was developed to provide panels of highest quality, seeking to fulfil the market segment that demands more sophisticated aesthetics solutions . The production of thermoset laminates and others, obtained using fibers-reinforced plastic, forming panels used in visual communication, publicity, signs, decoration, etc., were already shown in the documents CA1011240 of 31-05-1977, on behalf of Pidgeon John, US4126719 of 21-11-1978, on behalf of Koyanagi et al., and PI 9403679-9 of 05-10-1994, on behalf of Fusco Luciano, each one of them with objectives more or less similar to those now proposed in the present invention, not constituting prior arts or publications, considering the results and characteristics of the obtained products. The closest prior art is one described in the document PI 9403679-9 by the same inventor, which also consists of a continuous production of panels in fibers-reinforced plastic, intermixed with printed or decorated sheet, and that will be used here as reference and base of comparison. As it is known, any innovation, when put into practice, is always the starting point for new improvements, necessary in a modern, dynamic and globalized market as the one of visual communication. So, appears the necessity of constant research always heading to the same basic objectives of: - to improve the quality - to enlarge the application field - to reduce the production costs - to increase the production capacity Research and studies about the possibilities of implementing such improvements brought to the verification that the hot curing as well as the presence of organic peroxides catalyst, normally used in the continuous process for the production of fibers-reinforced plastic panels would be the main factors to be changed to achieve the objectives above mentioned. In fact, it was verified that this way of operation tended to provoke deformations, waves, porosity and other irregularities in the surface of any thermosetting continuous laminate. In the case of the production of decorated panels, the stage in which the resin passes gradually from the liquid state to the pasty, and from this to the solid, inside the heat curing chamber, is crucial for the laminating composition, because this is lengthened out during the haul off as the heating provokes adherence between the plastic composition and the platform, as well as the curing chamber extension increases the effort of the haul off. Such effort can result in deformation due to lengthening of the laminate and, as it is a composite formed by materials which are different, and therefore, they react differently, this can interfere in the performance of the process, demanding continuous controls and adjustments. This necessity, although reduced by delicate process fittings demanding highly specialized labor, prevents, nevertheless, the regularity and evenness of the laminate surface, as requested by the most sophisticated segments of the visual communication market, resulting in the significant process losses because of selective quality control. Another point to consider is that the hot curing cause the evaporation of the catalyst, normally organic peroxides, which can generate porosity on the surface of the laminate leaving it rough and liable to the dirt penetration, seriously compromising the visual quality of the obtained panels. It should be also added, as another difficulty to obtain a high quality product, by a process economically viable, the fact that the use of high temperature in the poiimerization of the panel restricts the choice of decoration materials, both the substratum and the printing inks used. The laminate curing evolution is measured, in practice, by the superficial hardness expressed in Barcol degrees and in case of a polyester resin, the complete curing is reached at about 50° Barcol according a "temperature-time" compromise. In the hot curing process the laninate doesn't reach its complete curing in the production line. At the best, the laminate will be approximately 20° Barcol at the end of the production line and the curing completion at room temperature will take several days long. In the meantime the product should be kept strictly flat, otherwise any deformation would be permanent. To solve the problem it has been tried to increase the temperature and/or the length of the hot chamber, without reaching practical results. That was because the temperature of the hot chamber is limited by the temperature resistance of the laminate component materials, meanwhile the length of the hot chamber is restricted by obvious space limitations, that is, to intend to reach the complete curing inside the hot chamber would demand impossible dimensions. Then, it can be deduced that the continuous production of panels and similar, by hot curing, as provided in the referred patent PI 9403679-9, should demand relatively high storage of finished products stocks, while the cure is completed at room temperature or, as an alternative, high costs for the set up and operation of post-cure chambers. Both solutions implicate space, tied up capital and corresponding impact in the final cost of the obtained product. In a further limitation, the presence of the catalyst and the thermic inertia of the hot chamber impedes to stop the production line to make fittings, controls, recharge of the feed materials, production shifts, etc., making the production rather complicate. To avoid all these inconveniences and in the purpose of overcoming them, a new continuous production process was developed, introducing ultraviolet radiation to cure the continuous laminate, as well as a series of innovations that will be properly detailed in the description of the process. So, the obtained products are technically improved, presenting differentiated technical characteristics, obtaining surfaces perfectly even and glass looking. As final result, this invention provides the following advantages: 1 - better quality of the laminate surface, perfectly even and with glassy appearance, essential in visual communication and decoration products, eliminating the irregularities and typical defects of the heat curing and the clumsy desplacement into long chambers, such as: porosity, waves, contractions, cellulite and other deformations; 2 - larger operation speed (up to 300 meters per minute against approximately 5 meters per minute in the heat curing process) revolutionizing the productivity; 3 - shorter curing area (from 30 meters to 1 m, approximately); 4 - easy operation because of the UV radiation features, as well as the absence of the catalyst, allowing the switch on / off of the production line without any problem, again and again. 5 - the laminate cures instantly and completely on the production line, avoiding the necessity of stocking products and / or the necessity of post-cure chambers for its maturation or, otherwise, the permanent deformation by the memory effect. 6 - notable reduction of the necessary space for the production and of the time of production; 7 - the maintenance of the equipment is practically none; 8 - smaller energy consumption; 9 - great economy in the product final costs (reference 30%, according to preliminary tests accomplished with production speed of 25 m/min); 10 - kinder to the environment, due to the non existence of evaporation of the organic peroxides and for minimal evaporation of solvents of the resin. The continuous process proposed by this invention consists of forming two fibers-reinforced resin layers, catalyst free, one layer on each face of a continuous decorated sheet , so that such sheet is wet by the resin of the two layers, front and back, and that such two fibers-reinforced resin layers join each other through the sheet, becoming an only material. Such a continuous compound strip, set between two carrier / moulding films, is forced to pass, in sequence, through laminating cylinders and lamination / pultrusion mechanisms, through a UV radiation photocuring set, and, finally, through cut and finishing set of the panels. The panels so obtained consist in a laminate/pultruded constituted by two fibers-reinforced resin layers, formed one on each face of a decorated sheet , and the two fibers-reinforced resin layers are adequatedly consolidate and join each other through the decorated sheet, becoming an only material that conforms decorative panels of perfectly even, glass looking surface, free of deformations and porosity. It can also be provided, optionally, layers of superficial finish by the incorporation of front and/or back film, by a layer of gel-coat or by veil of polyester or similar and others. The enclosed drawings illustrate the basic concept of the continuous production process of panels and similar, object of this patent , in which: Fig.1 - shows a general outline of the proposed process and of its equipments. Fig.2 - shows a view of a panel obtained by the process; Fig.3 - shows a cross-section A - A , according to Fig. 2; Fig.4 - shows a comparative graphic between the speed of the heat curing provided in the referred patent PI 9403679-9, in relation to the speed of the UV curing proposed in this patent, and Fig.5 - shows in an indicative graphic the relationship " temperature X time " of the heat curing, according to the process descript in the patent PI 9403679-9 mentioned as a reference. According to the illustrations above, the purpose of the continuous production process object of this patent, is the production of high quality panels, plates and similar (22) formed in resin (5)(11) reinforced with fibers (8)(13) intermixed with decorated sheet (9), used in visual communication or others, also object of this patent. So, the production process includes, essentially, four main continuous phases, described below, in this order : - Phase "a" : formation of a compound of resin (5)(11) reinforced with fibers (8)(13), intermixed with a continuous decorated sheet (9), made on an flat platform and between two carrier and moulding films (1)(15), releasing or integrating, so being that the compound constituent materials are fed in appropriate sequence, and from appropriate equipments, such as : carrier film (1), first resin layer reinforced with fibers (5)(8), continuous sheet of decorated material (9), second resin layer reinforced with fibers (11)(13) and upper film (15), emphasizing that the resin (5)(11) mentioned is free of catalyst organic peroxides but containing, instead, UV photoinitiators. - Phase "b" : lamination / pultrusion of the formed compound according to the previous phase, consisting of forcing the compound to pass through a lamination set (10) and through a lamination / pultrusion set (16), including appropriate mechanisms, so that the two fibers-reinforced resin layers (5)(8) and (11)(13), formed one on each face of the continuous decorated sheet (9), join each other through the sheet (9), becoming an only material, that constitutes the continuous laminate/pultruded strip of panels, and the mentioned laminating mechanism consists of a first unit of lamination (10) of partial consolidation of the laminate and in a second unit of lamination/pultrusion (16) of final consolidation, pultrusion and calibration of the continuous composite. - Phase "c" : consists in the passage of the continuous laminate/pultruded composite strip through an ultraviolet light radiation set (18), where it reaches its instant and complete curing. UV photocuring includes substantially one or more groups of UV lamps, projecting an intense ultraviolet light in a narrow crossing line on the continuous laminate/pultruded composite strip, and, depending of the kind of product to be obtained, can provided one or more groups of UV lamps, placed in sequence, both above and below the continuous composite. In case of being one or more groups of lamps below the continuous composite strip, the platform will be interrupted or it will be built of UV light permeable material, preferably quartz or other, in the UV radiation incidence area. - Phase "d" : passage of the continuous laminate/pultruded composite through cut and finishing mechanisms (21), where the panels (22) are separate from the continuous strip, according to dimensions previously settled. The cut can be made by disks, guillotines, laser, water jet or others. Along the mentioned four main phases, the continuous composite is hauled off by a mechanism of wheels, cylinders, caterpillar, or others (19) capable to provide the necessary advancing speed up to 300 m/min. Optionally, are provided rewinding set (20) of the carrier/moulding films (1)(15). Also, means of giving different superficial finishes to the produced panels, as for example several textures or to provided addition of further layers. One possibility of surface finish of the panels, is a polyester veil or similar (7)(14) to be provided, preferably light (for instance: 10- between the second Teed of fibers (?3Tanα tne laminationi uftrusio'n set p8). a Another possibility is that the carrier/moulding films (1)(15), can be incorporate to the laminate, so as to become its skin, but, in this case, the films will have one of its faces chemically activated. Yet a further possibility of surface finish would be an optional gel-coat layer (2) to be provided before the feed of the first resin/fibers layer (5)(8) on the carrier film (1), in which case a set of calibration (3) will be also provided as well as a UV partial curing set (4) for the partial cure of the " gel-coat " layer. As it is known, "gel-coat" is the so called resin layer usually used to form the superficial finish of thermoset parts or laminates. This resin, colourless or pigmented, is just cured partially, before the application of the following layers. Imediately after the feed of the resin (5)(11) and, optionally, after the feed of the " gel-coat " (2), additional operations of regularization of these layers are provided by "doctor-blade" set (3)(6) and (12). Between the lamination/pultrusion (16) and the UV curing set (18) a profile mechanism (17) is provided. In the continuous process of production here described, the feed order, as well as some characteristics of the materials can have small variations to origin panels of different constitutions, in order to fit special uses, as long as it is always maintaining the same technical effect that constitute the basic objective of the present invention. So, optionally, instead of two set of resin/fibers feed to be provided, (5)(8) and (11)(13), to cover both faces of the continuous decorated sheet (9), only one set of resin/fibers feed, (5)(8) or (11)(13), can be used, so as to reinforce the panels (22) just in its front face or in the back face only. The reinforcement fibers (8)(13) used in the process can be constituted of any fibers variations that fulfil the requirements of translucity, resistance, compatibility with the resin, cost, according to the panel specifications, being, preferably, glassfibers under shape of continuous strands to be chopped, chopped strands mats, woven roving fabrics, veils or others. The resin (5)(11) preferably used in the process belongs to the family of the polyester resins, unsaturated, photosensitive, colorless or translucent or, still, pigmented, according to the panel specifications. Other types of resins as the vinilesters, epoxidics, melaminics, phenoiics or its combinations can also be selected. The resin is selected to satisfy others additional requirements as the resistance to ageing, darkening, weathering, thermodeformation temperature, low contraction profile, mechanical/chemical resistance, low viscosity to facilitate the impregnation of the decorated material, etc. Low viscosity can be obtained in the formulation of the resin and/or by heating it before using. The kind of decorated sheet (9) to be used depends on the characteristics of the panel to be produced. Natural or synthetic paper, tissue, cloth or fabric are preferable, though any material impregnable or compatible with the resin and suitable to be printed or stamped or somehow decorated, with good image definition and resolution, with legends, messages, decorations and others , in any colors, can be used as well. In case of "backlight" panels, the decorated sheet will be selected to favors the diffusion of the light with appropriate transmittancy. The inks used in the decoration sheet (9), are selected to fulfil such requirements as compatibility with the resin, resistance and solidity to the light rays, specially UV, accordingly with the use and life expectation of the panel, appropriate pigment concentration so as to print with low ink loads, formulation avoiding any releasing components as silicons, waxes, etc. The carrier/moulding films (1)(15) are preferably of saturated polyester or similar and its surface can be, accordingly to the project specifications, brilliant, matte, texturized, releasing or chemically activated to be incorporate to the laminate and permeable to the UV light to allow the cure by radiation of the laminate. The basic conception of the above described process, object of this invention, allows introduce small modifications relatively to materials, dimensions and constructive details admitted in the same basic context and inventive unit, as long as it doesn't surpass the ambit of the granted protection.

Claims: CLAIMS "CONTINUOUS PROCESS FOR THE MANUFACTURING OF THERMOSET PANELS USED FOR VISUAL COMMUNICATION OR OTHERS APPLICATIONS, CURED BY ULTRAVIOLET RADIATION", characterised by the fact that includes the following four main continuous phases : "a" : formation of a compound of unsaturated resin (5)(11) reinforced with fibers (8)(13), intermixed with a continuous decorated sheet (9), on a flat platform and between two carrier and moulding films (1) (15), releasing or integrating, sliding lenghtwise on the platform, so being that the compound constituent materials are fed in appropriate sequence, and from appropriate equipments, such as: carrier film (1), first fibers-reinforced resin layer (5)(8), continuous decorated sheet (9), second fibers-reinforced resin layer (11)(13) and upper film (15), emphasizing that the resin (5)(11) is catalyst free, but containing, instead, UV photoinitiators. "b" : lamination of the formed continuous compound strip according to the previous phase "a", consisting in forcing the compound strip to pass through a laminating devices (10)(16) so that the two fibers- reinforced resin layers (5)(8) and (11)(13), formed one in each face of the continuous decorated sheet (9), join each other through the sheet (9), becoming an only material, that constitutes the continuous laminate strip of panels, and the mentioned laminating set consist of a first unit of lamination (10) of partial consolidation of the laminate and in a second unit of lamination/pultrusion (16) of final consolidation, pultrusion and calibration of the continuous composite strip. "c" : curing, by the passage of the continuous laminate composite strip through a photopolymerization set (18), that includes substantially one or more groups of UV lamps, projecting an intense ultraviolet light in a narrow crossing line on the continuous laminate/pultruded composite strip, and, depending of the kind of product to be obtained, can be provided with one or more groups of UV lamps, placed in sequence, both above and below the continuous composite strip, and in case of having one or more groups of lamps below the continuous composite strip, the platform will be interrupted or it will be built of UV light permeable material, preferably quartz or other, in the UV radiation incidence area. "d" : passage of the continuous laminate/pultruded composite strip through cutting and finishing mechanisms (21), where the panels (22) are separate from the continuous strip, according to previously settled size. 2. process in agreement with claim 1 , characterised by the fact that immediately after the feed of the resins (5)(11), "doctor-blade" mechanisms (6)(12) of calibration of the resin layers are provided. 3. process in agreement with claim 1 , characterised by the fact that between the laminacao/pultrusao mechanism (16) and the UV curing set (18) a profile mechanism (17) is provided. 4. process in agreement with claim 1 , characterised by the fact that along the mentioned four main phases the continuous composite strip is hauled off by a mechanism of wheels, cylinders, caterpillar, or other (19). 5. process in agreement with the claim 1 , characterised by the fact that after the passage of the laminate/pultruded strip through the haul off mechanism (19) rewinding sets (20) can be optionally provided to rewind the carrier/moulding films (1)(15). 6. process in agreement with claim 1 , characterised by the fact that the resin (5)(11) is unsaturated, photosensitive colorless or translucid or pigmented, chemically and mechanically resistant, preferably polyester, vinylic, epoxidic, melaminic and phenolic resins or their combinations. 7. process in agreement with claim 1 , characterised by the fact that the reinforcement fibers (8)(13) are natural or sinthetic fibers, compatible with the resin and with adequate characteristics of mechanical resistance and translucity, being preferably glassfibers of any variation such as continuous roving to be chopped, chopped strand mats, woven roving fabrics, glass veils, etc. 8. process in agreement with claim 1 , characterised by the fact that the employed inks to print, stamp, dye or paint the decorative sheet (9) are compatible with the resin, have adequate resistance and solidity to the light, appropriate pigment concentration so as to print with low ink load, and its formulation is free of releasing components as silicons, waxes, etc. 9. process in agreement with claim 1 , characterised by the fact that the carrier/moulding films (1)(15) are made of saturated polyester or similar, translucid and permeable to the UV light, and its surface can be brilliant, matte, decorative texturized, releasing or chemically activated so as to be incorporated to the laminate. 10. process in agreement with claim 1 , characterised by the fact that the decorated sheet (9) is any material impregnable or compatible with the resin (5)(11) and suitable to be printed or stamped or somehow decorated, with adequate image definition and resolution, with legends, messages, signs, decorations and others, in any colors, being preferably paper made with natural or synthetic fibers. 11. process in agreement with claim 1 , characterised by the fact that, to give a different superficial finish to the panels (22), an optional gel-coat set (2), is provided before the feed of the first fibers- reinforced layer (5)(8) as well as a "doctor blade" set (3) and a UV partial curing set (4). 12. process in agreement with claim 1 , characterised by the fact that, optionally, to give another different superficial finish to the panels, a polyester veil or similar (7)(14) are provided, between the first resin feed (5) and the first feed of fibers (8) and/or between the second feed of fibers (13) and the lamination/pultrusion set (16). 13. process in agreement with claim 1 , characterised by the fact that, optionally, instead of two set of resin/fibers feed, (5)(8) and (11)(13), be provided to cover both faces of the continuous decorated sheet (9), only one of them can be used, so as to reinforce the panels just in its front face or in the back face only. 14. process in agreement with claim 1 , characterised by the fact that the layers of fibers-reinforced resin (5)(8) and (11)(13) formed either in the front or in the back face of the continuous composite strip can be multiple layers and they can be combined or intermixed with stuffing or structural core layers such as "coremat", cellulose or others, translucent or not. 15. "OBTAINED PRODUCT" consisting of thermoset panels used for visual communication and other applications, produced by the process in accordance with the previous claims, characterised by the fact that the curing process is by ultraviolet radiation, and are conformed by the lamination/pultrusion of two set of layers of fibers- reinforced resin (5)(8) and (11)(13) formed one in each face of a sheet decorated with any images (9), and the two set of fibers-reinforced resin layers are conveniently consolidated so as to join one another through the decorate sheet (9), becoming an only material, having perfectly even and glassy surface, free of porosity and irregularities, providing options to give different superficial finishes by additional layers or formation of textures.

Inventors: FUSCO LUCIANO, FUSCO, LUCIANO
Applicants: FUSCO LUCIANO, FUSCO, LUCIANO
Application year: 1999
Main classification: B32B27
IPC codes: B29C35, B29C70, B32B27, B32B33, B44C5