FR2581929A1 - Thermally-insulating, gas-impermeable and printable laminate, process and plant enabling it to be manufactured - Google Patents

Abstract

The invention relates to a three-layer product, which is thermally insulating, impermeable to gases such as water vapour (air humidity) and printable, and its manufacturing process. The production of this laminate is achieved by hot pressing a polystyrene foam sheet 1 between a paper sheet 2 and an aluminium foil (sheet) 3, both of them being precoated with a hot-melt adhesive on their surface facing the polystyrene foam. This laminate combines thermal insulation, gas impermeability, stiffness, lightness, shock absorbency and printability.

Description

 The present invention relates to a three-layer thermal insulating product, impermeable to gases such as air humidity and mprimabla, as well as its manufacturing process.

 There are currently composites based on expanded polyethylene coated paper, especially for the manufacture of nti-shock packaging. The assembly of components is often cold and the final product is appreciated for its flexibility and its anti-shock properties. Moreover, the composite is not very insulating, trams permeable to gases and too flexible to allow the realization of rigid packaging.

 There are also laminates consisting of a layer of expanded polysheet foam covered with a plasticized film.

 The hot joining of the components is carried out by interlacing them by extrusion, an intermediate plastic film in the molten state, as described in the corresponding method. If it wishes to multiply the number of layers, it is necessary to multiply by the same number of intermediate films and consequently the number of extruders with flat filaments for depositing this film. The manufacture of such a product therefore requires the use of a large material. In addition, the settings of the molds and the speeds of running of the components must be very precise, in order to avoid the destruction of the expanded polystyrene. in time they are not constant and their variations are source of many rejects. The properties of such a material are modest because the aforementioned plastic sheet, coated with a fine aluminum deposit, is not a gas barrier since the aluminum deposit is too heterogeneous to present such a propridtd difficult to obtain.

The laminate obtained can not be shaped otherwise by thermoforming, after its manufacture and storage. Indeed, auite has two successive conformations, the laminated strip is not flat even after unwinding.

 Figure 1 shows the manufacturing device of the already existing laminate to explain the conformations of the final product.

 The expanded polystyrene is extruded by a circular die (10) onto a cylindrical refrigerant shaper (ii) according to a known method.

the expanded polystyrene is therefore a first shaped liver in tubular form (12) by cooling its molecular structure. The sheath formed (12) and then opened according to one of its generatrices by a knife (13) to form a non-flat strip (14) drawn by rollers (15) and covered with an extruded plastic film according to the method described in the patent corresponding. After covering with an extruded film, the still hot laminate is wound on a mandrel (16) and is reinforced a second time under the action of a new cooling 8 the air and coil winding (1-7) The storage of the laminate for at least 48 hours before conversion is necessary in order to permit the ripening of the expanded material, ie the evaporation of the residual blowing agent, this agent being in the state gaseous at room temperature. There can therefore be immediate transformation of the laminate directly after the joining of its components. After the maturing period, the laminate coil is unrolled and the strip is thermoformed.

 Finally, neither the expanded polystyrene side, nor the plastic film face, even aluminized, na allow the reproduction of complex and multicolored impressions, this because of their very low polarity and their surface state preventing a good adhesion of the inks .

 There is therefore currently no laminate plans combining rigidity, lightness, thermal insulation, impermeability gas, printability.

The invention makes it possible to remedy these drawbacks and particularly aims at the manufacture of a material consisting of three integral layers: a central layer of polystyrene foam (1), covered on one side with a sheet of paper (2) previously coated with a heat-sensitive adhesive on its face 82!) facing the foam (1), and on the other side, covered with a sheet (3) aluminum gas barrier, also previously coated on its face (3) facing the foam (1) of the hot melt adhesive already mentioned.The joining of the components is obtained by melting the hot melt glue and hot pressing using two heating cylinders (S1) (52)
Figure 2 shows in section the three-layer laminate according to the invention.

 Figure 3 schematically shows the installation for the realization of the laminate according to the invention for the purpose of race.

 Figure 4 schematically shows the installation for producing the laminate according to the invention, in top view without bandwidth.

 FIG. 5 schematically shows the details of the unwinding zones of the three components, the first deconformation, the solids of the three components and the final deconformation of the stra tified according to the invention.

 FIG. 6 represents the detail of the joining of the components of the laminate according to the invention.

 According to a first characteristic of the invention, the polystyrene foam (50) obtained by tubular extrusion and packaged in the form of a coil according to a known method is unwound in bandwidth (1).

 According to one of the features of the invention, the printable paper sheet (2) is pre-coated on its face (2) facing the polystyrene foam (1), a thermofusible polymer adhesive including 4 base of low density polydthylene low softening point of the order of 110 to 1200 C or ethylene vinyl acetate copolymer h softening point of the order of 70-800 C.

The coating is compatible with polystyrene foam, paper and aluminum and is made hot by a known method using inking printing rolls. After coating and drying the glue, the sheet of paper is packaged in a reel prote to be unrolled to be against glued.

 According to another characteristic of the invention, the aluminum foil (3), a total gas barrier, is also coated on its face (3) facing the foam (1) of the same hot-melt polymeric adhesive as that mentioned above. and is rolled into a reel ready for gluing after coating and drying, according to the same methods as the paper sheet (2). However, in order to withstand high stresses and stresses during unwinding of the coil at the time of implementation, the aluminum sheet can be glued against before coating on a paper reinforcing sheet.

 In this case, the face of the paper sheet next to the polystyrene foam (1) will be coated after collagen against the mofusible adhesive already cited and this by the same printing process to keep the outer face of aluminum.

 According to another of the features of the invention, the installation comprises at least three rollers (54) (55) (56) provided with internal brakes and with an axis parallel to those of the heating rollers (51) (52) (53). ) of the frame (57) rotated by motors and heated by high temperature fluid circulation. The two lower heating rollers (51) (52) form a median plane (M) where the various components are joined together. The frame (57) of the three heating cylinders (spi) (52) (53) also supports three cylinders tensioners (58) (59) (60) in free rotation which, together with the action of the internal brakes of the unwinders and the pulls exerted by the rotation of the pressure heating rollers (51) (52), make it possible to tension each bandwidth 9 secure and prevent wrinkling before hot pressing.

 The installation also comprises various free rollers (40) on which the laminate obtained (100) slides, different ramps of infra-red resistors (41) (42) for heating the polystyrene foam (1) at different stages of production. transformation to reduce its initial conformations previously described, a draft bench (43) equipped with two rotary press rollers (44) (45) and an automatic cutter (46) whose closure is engaged by the rupture the light beam between the photocell (49) and the reflective band (30). Finally, a treadmill (31) driven by a motor (32) allows the evacuation of cut formats (ion) to the flat conditioning pallet (33).

 The subject of the invention is also the product obtained by means of the installation above.

 This product is in the form of a strip (100) with three integral layers, cut into sizes to the desired dimensions. The invented laminate can be used for all applications that combine thermal insulation, gas impermeability, rigidity, lightness, shock absorption and printability. As an example, it can be noted the manufacture of protective housings for products sensitive to shocks, temperature variations and humidity of the ambient air.

The laminated formats produced according to the invention are pre-cut and pre-cut according to known methods used for converting the cartons and are shaped by folding at the time of packaging of the products to be protected.

 According to a preferred embodiment of the invention, the polystyrene moss (50) is unwound at the bandwidth (1) under the action of the traction exerted by the rotation of the heating rollers (si) (52). The web (1) is tensioned, without reaching breaking, under the effect of the tensions (d) exerted by the unwinding brake (54), the tensioning cylinder (5B) - and the rotation of the rollers (S1) (52) . The polystyrene foam is then heated to the surface and b heart b a temperature of 60 h 70 C near its softening temperature.On the outer face (1 ') of the foam (1) the heating is obtained by thermal radiation of resistors infrared (41) and on the inner face (1 ") by thermal conduction in contact with a heating cylinder (53) rotating clockwise (a).

 The surface temperatures of the heating elements, i.e. infra-red resistors and roller (53), are set to provide the calories corresponding to an intrinsic temperature of the polystyrene foam of 60 to 700 C, this depending the linear running speed of the web (1) thus the contact time with the cylinder (53) and the infra-red radiation (41). For example, for a running speed of the web 10 m / min we will work with heating elements at 70 - 80 C on the surface. If the speed of scrolling increases, in order to speed up the production rates, it will also be necessary to increase the heating temperatures to obtain the same heat exchange and the same temperature of the polystyrene moussa.

 During this heating, the polystyrene strip (1) is extended as a result of the actions described above. The combination of the temperature rise to 50-700 ° C. and the tensions tend to allow the structural relaxation of the foam and consequently to reduce the previous conformations due to tubular extrusion and coil conditioning as previously described.

 The aluminum coil is unwound and the sheet is stretched according to the system already stated, using a unwinder (56) equipped with an internal brake, a tensioner (59) and the rotation of the heating rollers (51) (52). The uncoated outer surface of the hot-melt glue of the aluminum foil (3) is unrolled facing the heating roll (51) rotating in a non-clockwise direction (b) and is pressed against it.

By thermal conduction through the aluminum and optionally through the paper reinforcing sheet, the heat energy supplied by the heating roller (51) allows the softening of the tharmofusible polymeric coating, placed opposite the polystyrene foam (1). ).

 If the hot-melt glue is based on polyethylene, the rollers (51) (52) are surface-heated to 120 - 1300 ° C for a vitasse de passeril bandwidth of the order of 10 m / min. These temperatures are obtained by internal circulation of water in overpressure or special oil and must be adjusted according to the passage vitae of the elements to be joined, as it was specified during the description of the first relaxation of the polystyrene foam tape (1).

 The reel of paper is also unrolled and stretched, according to the method already stated previously, using the unwinder (55) provided with an internal brake, the tensioner (60) and the rotation of the rollers (si) (52). ). The uncoated outer surface of the glue of the paper sheet (2) is unrolled opposite the heating roller (52) rotating clockwise (a). By thermal conduction through the thickness of paper, the heat energy provided by the roll (52) allows the softening of the tharmofusibla polymeric coating previously deposited on the face (2 ') facing the polystyrene foam (1) .

 Driven by the rotation of the heating rollers (51) (52), the three strip elements (1) (2) (3) are joined in a single product (100) by hot pressing at the median plane of attachment (M ). The spacing (C) between the heating rollers (si) (52) at the median plane (M) is set to be slightly less than the sum of the thicknesses of the layers to be joined, in order to exert on the materials passing a light contact pressure of the order of 0.5 to 1 MPa and allow the assembly of the compressors by hot pressing.

After joining, the laminated sheet (100) is drawn and
endue under the effect of the traction exerted by the rollers (44) (45) d draw (43) rotating in the opposite direction. The rotational speed of the draw rolls (44) (45) is slightly greater than that of the heating rollers (51) (52) so as to provide a (10) otherwise (D) of the laminate sheet (1) without attaining breakage. of one of the layers.

 Under the thermal radiation of several infra-red resistance ramps (42), the laminated sheet is heated to 60-700C.

As previously explained, the polystyrene foam sheet (100) is now fully deconformed by molecular relaxation in temperature and under tension. After cooling before the draw bench (43) the sheet (100) is flat and all traces of previous conformations has disappeared.

 The laminate (100) obtained, drawn by the rollers of the draw bench (43), is introduced between the upper (47) and lower (48) knives of the automatic shear (46). When the downstream end of the laminate (100) interrupts the light beam between the pheteelactric cell (49) integral with the shear frame (46) and the reflective band (30) integral with the conveyor belt (31), the movable upper knife ( 47) of the shear closes rapidly on the fixed lower knife (48), thereby cutting the three-layer laminate sheet (100) over its entire width and thickness. Immediately after this cutting the upper knife (47) quickly returns to an initial position "open", scrolling the laminate is not interrupted and continues indefinitely. The cut planar format (101) is driven by the treadmill (31) to a pad conditioning pallet where all the cut formats stack automatically and when the new laminate (100) downstream interrupts the aforementioned beam, a new fast cut is made. The invented manufacturing process is therefore continuous.

 The dimensions of the laminated formats are adjustable. In the direction of travel, longitudinal direction, the length obtained depends on the distance between the cutting plane (P) of the shear (46) and the cell (49).

 This spacing is adjustable by translating the photocell (49) guided by two slides (34) (35) integral with the frame of the shear (46). In the direction perpendicular to the scroll, transverse direction, width depends on the widths of the three components solidarisa but it is possible to vary this width by a longitudinal cut made by a thin knife '36). This adjustable position knife slides transversely on a ramp (37) integral with the frame (57) of the shell and perpendicular to the direction of travel of the laminate obtained (10D) .The transverse position of this knife depends on the desired widths.

 The invention described provides laminated formats in three layers, planes, to the desired dimensions, thermal insulation, gas-tight, rigid, lightweight, shock-resistant and impermeable

Claims (10)

 i) at least three layers of laminated product, in the form of cut-out formats, characterized in that it is obtained by hot pressing of a polystyrene foam sheet (1) between at least one fibrous sheet (2) and at least one metal sheet (3) impervious to gases.  2) laminated product according to claim 1, characterized in that the polystyrene foam sheet (i) has a fentiellent thickness of the order of 2mm to 10mm and is / is used after missement in the form of a coil unwound in bandwidth .  3) laminated product according to claim 1, characterized in that the fibrous sheet (2) is paper optionally printable with a basis weight of the order of 30 g / m2 to 150 g / m2, packaged in the form of a coil and unwound in bandwidth.  4) laminated product according to claim 1, characterized in that the metal sheet (3) impervious to gases is an aluminum foil with a thickness of the order of 7 microns to 12 microns, optionally bonded beforehand on a sheet paper reinforcement in order to withstand tensile stresses and to facilitate the coating of an adhesive, packaged as a coil and unwound in bandwidth.  5) laminated product according to the preceding claims characterized in that the fibrous sheet (2) and the metal foil (3) are coated, before use, on their side opposite the polystyrene foam (1), a thermo or fusible polymeric adhesive especially based on low density polyethylene / ethylene vinyl acetate copolymer.  6. A laminated product according to claim 5, characterized in that the hot melt thermoplastic adhesive is melt-coated on the sheets (2) and (3) by a known method requiring the use of printing rolls. inking.  7) A method of manufacturing a laminate product according to claim 1, characterized in that the joining of the components is obtained by hot pressing between two rotating heating rollers.  8) A method of manufacturing a laminate product according to claim 5 characterized in that the hot melt coatings of the fibrous sheet (2) and the metal sheet (3) are conduction brought to their softening temperature # to the contact respectively of the rotating heating rollers (52) and (51), and this before joining the components of the laminate.  9) A method of manufacturing a laminate product according to the preceding claims, characterized in that it allows to obtain a plane laminate by means of different operations of heating tension of the polystyrene foam (1) before and after stratification cation, in order to suppress the original conformations of it.  - a set of rollers (54) (55) (56) (ss> <s & equipped with internal brakes and tensioning rollers (58) (59) (60) to allow the smooth running of the various compounds of the laminated and that in the form of bandwidths.  10) Installation for producing the invented laminate according to the preceding claims, characterized in that it consists of  a set of heating cylinders (51) (52) (53), two of which rotate clockwise (52) (53) and one in a non-clockwise direction (51), the two lower rollers (51) (52) having a plurality of roles including the pulling of the components to be joined, the formation of a medial joining plane () by hot pressing, and the heating of the hot-melt glue coatings deposited on the side opposite the polystyrene foam (i) of the sheet fibrous (2) and metal foil (3).  - infra-red equipment for heating the polystyrene foam (1).  - A conveyor assembly (31) and conditioning stratified formats obtained (law).  - adjusting apparatuses (30) (34) (35) (37) (49) of the laminated format dimensians obtained (101)  - cutting devices (36) and (46) allowing the formatting of the obtained laminate (100)  - a traction bench (43) equipped with rotary pressing cylinders (44) and (45) for pulling and tensioning the laminate (100)