W closed cells process and apparatus for producing laminanted structure having hollo

Holder: Idem (7d) (74) Agent: Guetet & Bloch, Patent attorneys, 39, avenue de Friedland, Paris (8).

(54) Method for manufacturing a closed cell laminate and apparatus for implementing this method.

72) Invention of:

(33) (32) (31) Conventional priority: Patent application filed in Japan on December 21, 1970, n. 115.999 / 1970 in the names of the applicants.

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45864 the invention relates to an improved method and device for manufacturing a closed cell laminate.

Apparatuses are known for manufacturing laminates with closed cells, which comprise a rotary molding or forming cylinder having at its periphery a plurality of gas -permeable avenues so as to effect a marking or stamping · of a first film of thermally softened thermoplastic resin and comprising inside a vacuum chamber for sucking gas inside the cylinder through said cavities and a conduit for evacuating the gas sucked from the vacuum chamber outside the cylinder, a rotary bonding or adhesion cylinder for adhering a second thermoplastic resin film thermally softened to said first film molded or formed on the molding cylinder so as to form a closed cell laminate and a guide cylinder for bringing the laminate removed or detached from the molding cylinder at a position beyond the connecting cylinder (EUA patent No. 3,147,599, English patents Nos. 978,654, 942,214 and 942,215).

Closed cell laminates can be manufactured continuously using a device of this type, but improvements are necessary with regard to the molding speed, the dimensional stability of the cells formed, etc. the device, moreover, does not include a simple mechanism for changing only a molding member provided with gas-permeable cavities at its periphery in the case where a different marking is desired. Therefore, in such an apparatus, complicated and difficult disassembly and reassembly operations are necessary, or it is necessary to provide a separate device having another desired marking design. This is disadvantageous both in terms of operation and price.

the invention therefore relates to an improved method and device for manufacturing a closed cell laminate, of low cost price, at improved molding speeds and with

35- precise marking and where the molding member can be changed by a simple operation without the above drawbacks.

the invention also relates to improvements such as cooling the laminate formed on the molding or forming cylinder, cooling this cylinder, drying the cylin40 dre, and detaching the laminate from the cylinder.

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To this end, the subject of the invention is an apparatus for manufacturing a laminate with closed cells, of the type comprising a rotary molding or forming cylinder having at its periphery a plurality of cavities permeable to gases so as to effect marking, or stamping a first film of thermally softened thermoplastic resin and comprising inside a vacuum chamber for sucking a gas inside the cylinder through said cavities and a conduit for evacuating the gas sucked from the vacuum chamber at the outside of the cylinder, a rotary bonding or adhesion cylinder for adhering a second thermoplastic resin film thermally softened to said first film molded or formed on the molding cylinder so as to form a closed cell laminate and a guide cylinder for supplying the laminate removed or detached from the molding cylinder at a position beyond the connecting cylinder, apparatus characterized in that said forming or molding cylinder is mounted with clearance on a hollow support cylinder disposed inside, the vacuum chamber, which allows the passage of said support cylinder by sliding in a position between a point on said cylinder molding to which the first film has been brought and a point on said connecting cylinder to which the film has arrived, is fixedly mounted on said vacuum duct, in contact with the inner wall of said orous support cylinder, and there is provided a rotary balancing cylinder in contact with said molding cylinder, said balancing cylinder cooperating with said connecting cylinder and bringing said hollow support cylinder into intimate contact with the forming or molding cylinder.

the invention will be clearly understood on reading the following description made with reference to the appended drawing in which:

- Figure 1 is a schematic view in vertical section and side elevation of an example of apparatus according to the invention;

- Figure 2 is a schematic view in vertical section and side elevation of another example of apparatus according to the invention j

- Figures 3-1 and 3-2 are perspective views showing examples of closed cell laminate obtained.

- Figure 3-3 is a sectional view showing an example

45864 of closed cell laminate and obtained. by fusing a third film of a thermoplastic resin planar on the surface provided with cells of said laminate.

FIG. 1 represents an example of an apparatus according to the invention which can be used for the manufacture of a laminate with closed cells using a film still in the softened state by heat, extruded by an extruder E with head extrusion E provided with extrusion d d, d₂, d ^ for molding a film of synthetic thermoplastic resin. Of course, it is possible to reheat ready-made films made by other methods and bring them to a state of softening sufficient to be used in the present invention. In the devices shown in Figures 1 and 2, the molding cylinder is fixed horizontally relative to its axis, but it is obvious that this cylinder can be mounted perpendicular, or oblique to the horizontal. In FIG. 1, the apparatus is suitable for manufacturing a laminate of the type in which a first film E ^ and a second film Pg ″ as shown in FIG. 3-3 for example, are linked to one another. the other, then a third film E ^ is linked on the side opposite to the side E₂. When a laminated structure as shown in FIGS. 3-1 and 3-2 is desired, the device does not of course require any means for bonding the third film E ^. An example of this type of device is shown in Figure 2.

Referring to Figures 1 and 2, the molding cylinder MR is mounted with clearance on a hollow support cylinder SR provided inside and the radius of this cylinder SR is significantly less than that of the cylinder MR. The difference in radius is a function of the radius of the SR cylinder and cannot be determined precisely. Practically the internal radius of the molding cylinder MR is approximately 5 cm to 100 cm, the external radius of the support cylinder SR is such that the ratio of the internal radius of the cylinder MR to the external radius of the cylinder SR is between approximately 1.005 and 5 , and so that, in a position corresponding at least to a vacuum chamber 17 between a point of the molding cylinder MR to which a first film has been brought, and a point on a connecting cylinder PR to which the film is brought the cylinder MR is substantially in close contact with the cylinder SR.

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Preferably, the interior radius of the molding cylinder is between 7.5 and 50 cm, and the ratio of the interior radius of the cylinder MR to the exterior radius of the cylinder SR is between 1.01 and 2. Ratio of the radii MR / SR can also be chosen so that the cylinder SR comes substantially into contact with, for example, half or three-quarters of the periphery of the cylinder MR, including said position corresponding to the vacuum chamber 17.

The apparatus of Figure 2 has the same components. In all positions between a point of the cylinder MR to which the first film has been brought and a point of the connecting cylinder PR to which the film arrives, a vacuum chamber 17 is provided in contact with the inner wall of the hollow support cylinder SR and connected to a vacuum duct 14 so as to allow the sliding of the cylinder SS.

A rotary balancing cylinder BE is mounted in contact with the molding cylinder MR, this balancing cylinder cooperates with the connecting cylinder PR to bring the hollow support cylinder into intimate contact with the molding cylinder MR at the location of said vacuum chamber. Many of the BR cylinders and their positions can be changed as desired. Since the cylinder MR is mounted with clearance on the cylinder SR with a suitable tolerance, an aro-shaped gap S of small width is formed, as shown in FIGS. 1 and 2, on the side opposite the intimate contact zone. .

Preferably, a cooling device CZ is provided in a position situated beyond the connecting cylinder PR and before the laminate is removed from the cylinder MR. This cooling device solidifies the laminate formed on the MR cylinder by cooling and retains its shape allowing easy removal and it also cools the MR cylinder.

In FIGS. 1 and 2, the vacuum chamber 17 is connected to a shaft 10 of the cylinder SR by means of a vacuum duct. Aspirated gases are evacuated from the cylinder SR by a conduit 10a provided inside said shaft. If desired, the aspirated gases can be evacuated at another point by means known per se.

A cooling fluid ejection chamber 20, which is in contact with the inner wall of said support cylinder

45864 · 5 2118966 hollow on a part of the cylinder MR from where the laminate is removed or in the vicinity of this part but before the complete removal is mounted on a pipe 15 of arrival of cooling fluid such as cold air or cold water, the shaft 10 of the cylinder SR is connected to the conduit 15 and, through the shaft 10, the cooling fluid can be brought to the chamber 20. the chamber 20 cools the cylinder SR, facilitates the removal of the laminate from the cylinder MR, and also cools this laminate on the side of the film F ^, that is to say on the side opposite to the cooling device CZ, by orifices formed at the bottom of a plurality of gas permeable cavities.

. when means are provided for extracting the gases sucked in through the gas-permeable cavities passing through the vacuum chamber 17 and the conduit 14 connected to the shaft 10, it is possible to give the shaft^- 10 of the cylinder SR a double tube structure, one of the hollow parts being used as a conduit for extracting the sucked gases, the other being used as a passage for bringing coolant to the chamber 20. This is

- the preferred structure. Of course, other conduits can be provided for supplying a cooling fluid and, if desired, the extraction conduit for the aspirated gases and the conduit for supplying the coolant can be provided without using the shaft. 10.

the presence of an interstice in the shape of an area or space S of small width or thickness is useful for cooling the laminate on the side of the first film F ^, that is to say on the side opposite to the cooling device CZ. This increases the advantage of the apparatus according to the present invention in addition to the ease of exchange of the cylinder MR because it is mounted with play on the cylinder SR. In addition, the arc-shaped gap S serves to exert a cooling effect of the laminate from the interior of the MR cylinder over a large part of the interior surface of said MR cylinder.

the double hollow shaft 10 of the cylinder SR is mounted on a frame 9. the cylinder SR has a number of channels 11 for example on its outer periphery, and also a number of channels 12 which make them communicate with the interior of the SR cylinder. the shaft 10 includes the vacuum pipe 14 and the coolant pipe 15. one of these pipes

45864 6 2118966 or the »two can be rotatably mounted on the shaft 10. Thus, as required, the relative positions of the duct 14 and the fccnduit 15 can be varied by varying the angle between the duct 14 and the chamber d ejection of the cooling fluid 20. Therefore, as required, the relative positions of aspiration of the supplied film and of removal of the resulting laminate can be varied.

the chambers 17 and 20 are brought respectively into intimate contact with the inner wall of the support cylinder SR by means of springs 18 and 21 so that the cylinder SR can slide at this point. Instead of the springs, other means allowing this sliding can be used; for example, the conduits 14 and 15 can be replaced by expandable tubes. In the drawing, these chambers are closed with lips by fittings 16 and 19 · the previous intimate contact can be obtained by other known means such as cylinder seals or liquid detergents. If the sealing effect is good, the springs can be removed. Instead, the chambers 17 and 20 are directly connected to the passages 14 and 15 and can be fixed in desired positions only by the sealing means, without any risk of interfering with the rotation of the cylinder SR with the cylinder MR and without loss of sealing.

the molding cylinder MR and the support cylinder SR can be made of a thermally stable material, such as stainless steel, brass or other materials, reinforced plastics or synthetic rubbers, the body 22 of the molding cylinder MR has a plurality of gas-permeable cavities at its periphery to produce the marking of the first softened thermoplastic resin film; By changing the MR cylinder you can change the marking of the film. the outer peripheral surface of the cylinder SR is covered with a material such as a wire mesh, sintered metal plates permeable to gases, fabrics, nets of synthetic resins, nonwovens, or thin metallic sheets with fine pores, and this material constitutes the bottom of the cavities. If desired, the cavities of the MR cylinder itself can be independent with fine pores on the gas passage bottoms. the presence of such a gas permeable layer on the surface where the HR cylinder and the SR cylinder can enter

45864 contact is used to ensure the synchronous rotation of these two cylinders.

the rotation of the cylinder MR can be produced by friction between this cylinder and the cylinder SR, the rotation of the cylinder SS can be ensured by means of one or more drive rollers with a high coefficient of friction in contact with the internal wall of the cylinder SR. This rotation can also be produced by meshing a suitable part of the external end of the cylinder SR, by providing a pinion on the cylinder MR which meshes with the pinion on the cylinder SR and by rotating the cylinder SR. A similar gear may be provided on the body 22 of the cylinder MR on the edge and in the axial direction, and the cylinder SR is also rotated so as to drive the two cylinders in synchronous rotation. It is also possible to drive the cylinder MR in rotation by the preceding gear and the cylinder SR can be driven in rotation as a result. It is also possible to rotate the cylinder MR using the balancing cylinder BR as a drive roller.

The connecting cylinder PR can be rotatably mounted by suitable means and comprises for example a core cylinder 25 and a rubbery elastic layer 26 at the periphery. For example, a support arm 27 of the rotary core cylinder 25 is fixed to the chassis 9 by a pin 13 so as to freely control the angle of inclination. A threaded shaft 29 is screwed into a threaded cylinder 28 connected to the support arm 27 and a handle 30 is wedged on the shaft 29. It is thus possible to rotate the connecting cylinder around the spindle. It is preferable that the connecting cylinder PR has cooling means arranged to cool it from the outside and from the inside.

The balancing cylinder BR comprises, for example, a core cylinder 31 and a rubbery elastic layer 32. A support arm 33 rotatably supports the cylinder 31 and is fixed to the end of a double hollow shaft 10 of the molding cylinder MR to be moved up and down. It is preferable that said laminate is cooled to a position beyond the PR cylinder and before it is removed from the molding cylinder. Cooling can be done by blowing a coolant but it is preferred to use a coolant

45864 such as water. The coolant can for example be sprayed onto the laminate by a number of shower tubes arranged in series and having a number of small orifices directed towards the surface of the HR cylinder for example. Instead of the shower tubes, a curved water jacket can be provided along the surface of the MR cylinder, a number of small holes being provided on the surface facing the MR cylinder. It is also possible to use cooling means as shown in FIGS. 1 and 2.

In the cooling means CZ shown in FIG. 1, a mast 34 made of flexible material such as felt or sponge, which comes into contact with the surface of the cylinder MR under low pressure, is placed in a receptacle 35 provided of a spring plate 42. At the upper part of the mast 34, a water discharge tube 37 pierced with a hole 36 supplies a coolant such as water. By opening or closing a tap 40, the proper amount of water can be supplied to the top of the mast 34. The coolant flows while soaking in the mast 34 and flows through a hose. outlet 39 disposed at the bottom of an outlet box 38.

In the cooling device shown in FIG. 2, a mast 34 * made of felt, sponge, polyurethane foam, etc., is carried by a barrier plate provided in a suitable position for the receptacle 35 and a barrier for the cooling fluid. is formed between it and the cylinder MR. Water flows over this barrier member.

In Figures 1 and 2, the guide cylinder of the laminate removed from the molding cylinder MR serves as a water removal cylinder WR, being connected with the cooling member CZ using a coolant. This cylinder WR comprises a core cylinder 43 and a layer 44 made of a water-absorbing material such as felt, sponge or polyurethane foam, and a rotary pressure cylinder 45 is provided so as to compress this layer 44 absorbing water. As shown in FIG. 2, it is preferable to provide a dryer 40 for drying the surface of said cylinder in the vicinity of the molding cylinder MR on which the first film has been introduced. The dryer 40 can be carried by an arm (not shown) mounted at the end of the shaft 10 as in the case of the support arm 33

45864 of the BR balancing cylinder. When a coolant such as water is used in the chamber 20, a dryer can be provided inside the cylinder SR directed towards the interior wall of the cylinder SR, and carried by the shaft of the cylinder 10. can supply a flow of drying gas, for example through the shaft 10 (this can for example have the form of a triple tube).

To make a laminate of the type shown in the figure

3-3, it is possible to provide a device for adhering a third film as shown in FIG. 1, device fixed to the chassis 9.

In FIG. 1, the laminate T removed from the molding cylinder MR is guided by a suitable guide cylinder so that its second film face comes into contact with the surface of the heating cylinder HR. FIG. 1 shows an embodiment in which the water removal cylinder WR which is used in the case of a coolant is used as a guide cylinder and the laminate is guided towards the HR heating cylinder by the cylinder GR and cylinder WR. If desired, drying means such as the dryer 40, shown in Figure 2 are provided at any point until the laminate removed from the cylinder MR is guided to the heating cylinder HR. This can be used to dry and remove a liquid which can adhere to the first film when a liquid is used as coolant ejected from chamber 20.

The HR heating cylinder is heated from the outside by an infrared radiator, for example, and includes an internal heating device 49, for example electric, heated oil, or steam, inside d a cylinder body 48, in order to maintain the cylinder at the desired temperature. An external heating element 50, such as radiators or infrared lamps, is provided on the periphery of the cylinder body 48. It is preferable in this case to mount the heating member 50 on a cover 51.

The guide cylinder GR and the receiving cylinder CR can be ordinary cylinders. With regard to the CR cylinder, it is preferable to provide several groups of cylinders in series in the direction of advance, each cylinder group consisting of opposite upper and lower cylinders.

45864

There is provided a hollow cylinder DR of adhesion by fusion, internally cooled, rotated by the intermediary of the laminate and the third film E ^, is placed beyond the heating element 50 of the cylinder BR which is also heated the interior, in order to adhere the third film of thermoplastic resin by fusion on the laminate. Preferably, the DR cylinder is cooled by a suitable coolant, such as water, acting from the inside.

Preferably, the shaft 46 of the cylinder DR has a double tube structure and a coolant is introduced into the cylinder body 47 by one of the hollow parts of the shaft, for example 46a, and it is extracted from the cylinder body 47 through the other conduit 46b.

We will now describe the process for manufacturing a laminate of the type shown in Figures 3-1 and 3-2 from two films and Rg and a laminate of the type of Figure 3-3 further comprising a third film R ^ , referring respectively to Figures 1 and 2.

In FIG. 2, the first film R ^ of thermoplastic resin as extruded and thermally softened is brought to the surface of the molding cylinder MR and brought into intimate contact with this cylinder. MR by suction from the vacuum chamber 17 through the cavities 23 of the cylinder MR, and the support cylinder SR having the channels 11 and the orifices 12. Da film moves to the connecting cylinder ER by rotation of the cylinder MR while being molded according to marks corresponding to the shapes of the various cavities. In a suitable position before arriving at the cylinder ER, a second similar film Rg is brought to the first molded film and the two films are linked by the connecting cylinder. FIG. 2 shows an embodiment in which the connecting cylinder ER is cooled externally by cooling means comprising a receptacle 35 *, a mast 34 absorbing water, and a water supply duct 37 ', as this has been indicated for the cooling device CZ in FIG. 1.

The laminate formed on the molding cylinder MR is cooled at the same time as the latter while being brought by this cylinder MR onto a surface of the cooling water dam of the cooling system CZ. Then the laminate is cooled on the side

45864 of the first film also by a cooling fluid flowing from the interior of the cylinder SR through the support cylinder SR provided with flow channels 11 and cooling orifices 12 and through the cavities of the cylinder MR. At this time, the arc-shaped slot or gap S or space due to the mounting with clearance of the cylinder MR on the cylinder SR makes the cooling from the interior of the cylinder MR more efficient.

In addition, this flowing coolant allows easy and precise detachment of the laminate from the MR cylinder and also prevents any deformation of the laminate during detachment.

the laminate detached from the cylinder MR is freed from drops of water, etc., thanks to the water removal cylinder WR and, if desired, the adhering drops of water are additionally removed by a drier (not shown) ) similar to dryer 40 for the side of the first film. Thus, the desired laminate can be obtained from the films R ^ and R₂·

A third film R ^ can be adhered to by fusion on the face of the first film of the resulting laminate. In Figure 1, the laminate Τ_χ guide 'from the molding cylinder MR to a removal position, is guided on the cylinder GR so that its second film face comes into contact with the heating cylinder HR. The laminate is heated heated by the external heating element 50 and an internal heating element of the heating cylinder HR, and a third thermally softened film R ^ is adhered to the face of the first film, as extruded from a nozzle d ^ of die D, by the internally cooled adhesion cylinder DR. Undesirable deformations, such as warping or curvature of the three films at the time of melt adhesion of the third film can be effectively prevented.

Laminate obtained of the type of Figure 3-3, is gripped by the CR cylinder and brought to a cutting device having a good surface regularity and preventing warping.

If desired, suitable tension is exerted by the CR cylinders on the laminate composed of three films, to prevent its deformation.

With the apparatus of the invention, the strength, transparency, luster or other qualities of the product can be improved. In addition, the molding speed can be increased. Ceei

71- 45864 is the case when the device comprises external means for cooling by a liquid and a chamber for ejecting the cooling fluid provided in the internal wall of the support cylinder and, in addition, better quality of the product. Because the molding cylinder is mounted with clearance on the support cylinder, one can easily change the molding eylin dre to change the marking and the whole apparatus can be significantly simplified. In addition, the presence of an arc-shaped slot or gap serves to increase the cooling effect by the inner wall of the molding or forming cylinder.

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