FR2584019A1 - Device for producing foam blocks of polymers - Google Patents

Abstract

A device according to the invention is characterised in that it comprises a container including: - a shell 21 constituted by at least one vertical wall of a closed contour defining at least one compartment; - a bottom 22 disposed inside the said compartment 21, the edge of which, which defines it, extends parallel to and in the proximity of the internal face of the wall of the said compartment; - means 15 for providing sealing between the said bottom 22 and the said wall 21; - means 20 for producing the relative movement of the said bottom 22 and of the said shell 21 in order to vary the volume of the container and to position the bottom 22 with respect to the upper edge of the shell 21 and, - means 23/24 for applying at least one strip or a flexible sheath 4 against the said shell 21.

Description

 The present invention relates to a device for producing blocks of polymer foam.

 The technical sector of the invention is that of industrial installations for the continuous manufacture of foam blocks in which the liquid reactants are introduced into a container in order to generate an expanded foam.

 Among such installations, the casting of polyurethane foam by the vertical method is known in particular from patents DE-B-I 169 648 (MUNNEKE); FR-A-1 524 032 (BAYER); DE-A-1 504 091 (CONTINENTAL GUMMI) and FR-A-2 517 591 owned by the applicant.

 The object of all these processes is to produce blocks of foam of rectangular or circular shape and intended to be transformed by cutting or peeling. According to the methods implemented from such installations, the reactive mixture is introduced into a container having the same section as the block to be produced, which implies that the liquid mixture must be distributed over the entire surface before the start of the expansion.

 In practice, when the distribution ends, the liquid arriving at the points furthest from the supply orifices has a delay sufficient for the foam not to have the same structure over the entire section of the block.

 Installations are also known in which the reactive mixture is introduced at source into an opening of an elongated rectangular shape and delimited by two divergent walls and two parallel walls. The mixture entering into reaction is contained in a flexible envelope and is taken up by two inclined conveyors diverging upwards from said opening, the block of foam developing vertically. Installations of this type are described in patents B-B-741836 (TOMASONI) and EP-A-0114741 (HYMAN). These last two devices involve a relative movement between the walls, which induces leakage of the reagents still liquid at the moment when these are introduced into the enclosure formed by said parallel and divergent walls.

 Installations in which the mixture of reactants is introduced into a container to generate an expanded foam are further described in patents FR-A-2 330525 (UNIFOAM) and FR-A-2 502 541 belonging to the applicant and in which the foam s 'works horizontally.

 The UNIFOAM patent describes a container with variable volume and comprising two lateral walls which can be moved so as to determine the width of the strip of foam. The reactants are introduced through the bottom of the container where their expansion begins to occur. The reactants, in the form of nascent foam, overflow from the container and are taken up by a horizontal conveyor. The depth of said container is immutable, which results in fouling given the evolving nature of the mixture.

 A device making it possible to remedy this drawback is described in patent FR-A-2,502,541. According to this patent, the container is of variable volume and in particular comprises two side walls and one or two cylinders which form two curved walls, the whole defining a zone of retention of the mixture of reactants whose volume can vary in Rebut to maintain the liquid mixture and to pour it in this state on a conveyor on which the foam develops. Such a container is more particularly suitable for equipping an installation in which the foam develops in the horizontal direction.

 The present invention aims to provide improvements to the devices known for the manufacture of blocks of polymer foam.

 An objective of the invention is the continuous production of blocks of polymer foam of any cross section by means of a container comprising one or more compartments and adapted to obtain a good distribution of the mixture of reactants in the liquid state, so as to produce foam blocks of a homogeneous structure.

 Another objective is to obtain, at the outlet of the container, a foam in a sufficiently viscous state so that no pouring occurs while avoiding significant fouling of the container and whatever the formula of the foam.

These objectives are achieved by the device according to the invention for producing blocks of polymer foam from a mixture of liquid reactants comprising a container, the bottom of which comprises at least one orifice for admitting said reactants and means for unwinding at at least one flexible strip or sheath to tightly surround the container, characterized in that it comprises
- an envelope constituted by at least one vertical wall of a closed contour delimiting at least one compartment;
a bottom disposed inside said compartment, the edge of which delimits it extends parallel to and close to the internal face of the wall of said compartment;
- Means for sealing between said bottom and said wall;
means for causing the relative displacement of said bottom and of said envelope in order to vary the volume of the container and to position the bottom with respect to the upper edge of the envelope and,
- Means for applying said strip or said flexible sheath against said envelope.

 In one embodiment, the container is of an elongated shape and has rounded side sides.

 In another embodiment, the container is bent at least once in the direction of its length.

 In one embodiment, the envelope comprises at least one additional separating wall extending longitudinally and which divides it into at least two compartments in each of which is disposed a bottom.

 In another embodiment, said envelope comprises at least one additional dividing wall extending transversely which divides it into at least two compartments in each of which is arranged a bottom.

 Preferably the bottom which is arranged in each of said compartments is concave and of rounded shape, for example of a cross section of a generally semi-cylindrical shape.

 Said envelope comprises, around its upper edge, a flexible seal on which the strip or the flexible sheath is supported.

 In one embodiment, the envelope is fixed and the variations in altitude of the bottom in the envelope are obtained by double-acting cylinders.

 The device comprises around the edge of the envelope which comprises the flexible seal at least one member for supporting the strip or the flexible sheath on said seal.

 The device comprises around the edge of the envelope which comprises the flexible seal, two cylinders for supporting the strip or the flexible sheath on said seal, which cylinders are parallel to each other and to the longitudinal edges of the envelope and are mounted rotating about two axes located at said upper edge of the envelope, which cylinders have flared ends in the shape of a flag, parallel to the rounded ends of the envelope to press the strip or flexible sheath against the joint which s extends around the perimeter of the upper edge of the envelope.

The bottom of the container has, on its periphery, a flexible seal brought into contact with the internal face of the wall of said compartment to seal between said bottom and said compartment.
The advantages of the device according to the invention are numerous
- Possibility by varying the volume of the container by intervening over its depth, to control the state of the reactant mixture as it comes into contact with the strip or the flexible sheath and therefore to prevent any risk of leakage.

 - Possibility of producing all types of polymer foam: flexible, semi-rigid, rigid ...

- Possibility of producing blocks whose section has the shape of the finished product, avoiding subsequent cutting or limiting this cutting to shapes that could not have been obtained by direct casting;
- Low investment, the basic casting machine being able to receive different tools such as the former and the container adapted to a specific production;
- When the block in production is of a single bore: rectangle or square, we can make a change of section without interrupting production and vary, from the same formula> the final density of the foam by modification expansion volume during the foaming phase or, on the contrary, changing the formulation of the foam without changing the final dimensions of the block;
- Possibility of pouring one or more qualities of foam simultaneously to obtain, by combining them in the Ir'iocs es, comfort or color comfort effects, this possibility being more particularly applicable to flexible cold foam called foam high elasticity.

Other advantages and characteristics of the invention will become apparent on reading the following description of a device for producing blocks of polymer foam with reference to the appended drawing in which
- Figure 1 is a schematic sectional view of the lower part of a device according to the invention comprising a variable volume tank;
- Figure 2 is a schematic longitudinal sectional view of a variable volume container fitted to the device of Figure 1;
- Figure 3 is a view along arrow F of the container of Figure 2;
- Figure 4 is a view along arrow F of the container of Figure 2 comprising equipment for slitting and closing a tubular sheath;
- Figure 5 is a top view of Figure 2 ;;
- Figure 6 is a top view of a bent container adopting the general shape of an L
- Figure 7 is a top view of a bent container adopting the general shape of a U;
- Figure 8 is a view along arrow F1 of the container of Figure 6;
- Figure 9 is a view along arrow F2 of the container of Figure 7;
- Figure 10 is a top view of a container having two compartments separated by a longitudinal wall;
- Figure 11 is a top view of a container having three compartments separated by transverse walls;
- Figure 12 is a view along arrow F3 of the container of Figure 10;
- Figure 13 is a view along arrow F4 of the container of Figure 12.

 Reference is first made to FIG. 1 of the drawing which represents the lower part of an installation for manufacturing blocks of polymer foam developing vertically in the upward direction and to FIGS. 2 to 4 which illustrate a container according to the invention in an embodiment.

 It should be noted that the subject of the invention is not limited to a vertical installation but can be applied to any installation for manufacturing blocks or strips of polymer foam.

 As illustrated diagrammatically in FIG. 1, the installation comprises a frame 1 comprising a decking carried by posts 1b.

 The frame 1 supports a container 2 which will be described later, which container is extended downwards by a forming member 3 which, according to this example, is designed to open and close a sheath 4 coming from a roller 5 mounted for free rotation above the decking.

 k the lower end of the former 3, the installation comprises a roller 6 around which the sheath is partially wound 4. A roller 61, parallel to the roller 6 and arranged symmetrically with respect to the median plane of the former 3, is provided to receive the sheath from another roller 51 waiting to be unwound after exhaustion of the roller 5.

 Above the container 2, the installation first of all comprises a primary former 7 and a secondary former 8, on which the envelope containing the foam in formation rests and traction means 9 for the block of foam, associated with means for extracting the reaction gases to avoid the formation of caverns in the foam block.

 The example illustrated in Figure 1 is more particularly suitable for the manufacture of cylindrical foam blocks. The sheath 4 is slit in the direction of its length by a cutting device 10 comprising blades arranged below the decking la, in order to allow the sheath to pass through obstacles such as crossings of the decking la and the liquid reactants supply pipes in the mixing head. The slit edges are then reassembled by a gluing or welding device 11 to reconstitute the sheath 4 around the container 2, said edges being glued or welded with a filler strip 12 coming from rollers 13.

 It will be noted that the envelope of the foam block can also be produced by means of several films assembled together to form a sheath from the members described above.

 In one embodiment, the container 2 (FIGS. 2 to 4) consists of an envelope 21 constituted by a vertical wall 21a of a closed outline delimiting a compartment of elongated shape comprising two flat parts 21b / 2lc, connected together by two curved parts 2 1d / 21e of a radius R. The casing 21 is extended downwards by a skirt 3 having divergent walls 3a / 3b connected by rounded and flared ends 3c / 3d, as illustrated in Figure 3, so as to form a forming member for making a flexible sheath from several plastic films, for example two polyethylene films. The member 3 further comprises and in a known manner devices 11 for gluing or welding said films located at the lower part of said vertical wall 21a of the casing and rollers 14 for applying the films to the flared parts 3c / 3d of the organ 3.

 In another embodiment illustrated in FIG. 4, the forming member 3 has a profile in the shape of an ogive and is more particularly adapted to shape a flexible polyethylene sheath.

The container 2 has a bottom 22 which can be flat but which in a preferred embodiment is concave and rounded, for example the bottom 2 is of a cross section of a generally half shape
2 cylindrical.

The bottom 22 is delimited by two straight edges 2 a / 2 b and
2 2 parallel to each other, which edges are joined by two rounded edges of radius r 22c / 22d. The edges 22a / 22b / 22c / 22d of the bottom 22 are thus parallel and close to the parts 2 1b / 21c / 21d / 21e of the envelope 21. The seal between the envelope and the bottom is made by means of a seal. flexible 15, for example a lip seal attached by gluing or by any other means around the peripheral edge of the bottom 22, the lip or lips of the seal being applied against the internal face of the vertical wall 21a of the envelope.

 At its lower part, the bottom 22 has orifices 22f in which lead lines 16 for supplying liquid reactants. The pipes 16 are supplied by pipes 17 comprising a flexible part 17a to allow the bottom 22 to be displaced in height, which pipes are connected to a mixing head 18 supplied by tutulures 19.

 As illustrated in FIG. 2 and in one embodiment, the casing 21 is fixed and the bottom 22 is displaceable in height by means of two double-acting cylinders 20, for example hydraulically operated carried by pedestals 21. The two jacks 20 are synchronized so as to vary the altitude of the bottom 22 while respecting its perfect horizontality. The depth of the container 2 can thus vary in a proportion of approximately 1 to 3.

 The part of Figure 2 on the right represents the bottom 22 immobilized at its lower end.

 The part of said figure on the left illustrates the bottom 22 immobilized in the upper position close to the upper edge of the envelope 21.

 It follows from this design the possibility of varying the volume of the container 2 by intervening on its depth by moving the bottom 22 so as to permanently control the state of the mixture of liquid reactants whose reaction begins in said bottom and which expands to reach the upper edge of the envelope 21 in a viscous state to be driven by the sheath 4 which delimits the periphery of the foam block. The bottom 22 is therefore positioned relative to the upper edge of the envelope 21 according to the formula of the foam and therefore the reaction time of the liquid agents. According to the invention, it is therefore possible to avoid leaks between the sheath polyethylene lene 4 and the envelope 22 due to the consistency of the mixture developing at the upper edge of said envelope without fouling the container.

The seal between the envelope 21 and the polyethylene sheath 4 is produced by means of a support member which applies said sheath 4 against a flexible seal 22, for example a lip seal added by gluing or by any other means. around the top edge of the envelope
This member may be static and be constituted by a sort of continuous wall in one or two parts extending parallel and close to said upper edge of the envelope.

 In a preferred embodiment, the installation comprises two cylinders 23/24 arranged on either side of the envelope and mounted for free rotation around two axes parallel to each other and to the longitudinal edges which delimit said flat parts 21b / 21c of the envelope 21, which axes are located in the plane in which is said upper edge of the envelope. The two cylinders are for example (FIG. 1) mounted on two bearings 23l / 241 fixed to frames 25 carried by the frame 1.

 Each of said cylinders 23/24 has flared ends adopting the general shape of the horn of a wind musical instrument 23a / 23b-24a / 24b which are parallel to the rounded ends 21d / 21e of the envelope.

 These cylinders have the function of exerting a force on the polyethylene sheath 4 with a view to applying it against the seal 22 and ensuring sealing between the envelope 21 and the sheath 4.

 In a variant, not shown in the drawing, the cylinders 23/24 are motorized and are driven in rotation at the speed of unwinding of the sheath 4.

 Referring now to Figures 10 to 13 which illustrate other embodiments of the container according to the invention for producing blocks or strips of foam from different formulations in order to simultaneously obtain, by combining the foams, comfort and hold or color effects.

 An exemplary embodiment of such a container is given in FIGS. 10 and 12. The casing 2] is similar to that which has just been described with reference to figs 2 to 5 but has a central wall 21f parallel to said flat walls 2 1b / 2 1c and which divides the envelope into two compartments. In each of these compartments is mounted a flat or concave bottom 23/24 similar to that 22 which has just been described with reference to said Figures 2 to 5. The seal between the vertical walls of said compartments and said bottoms is achieved by seals flexible, for example with lips 25/26.

Each of the 23/24 bottoms is positioned relative to the edge on
34 inside the envelope by double-acting cylinders 27/28 and depending on the nature of the foaming reactants.

Another example of execution of the container is given in FIGS. 11 and 13 of the drawing. As for the container in FIGS. 10 and 12, the envelope 21 is similar to that which has just been described with reference to FIGS. 2 to 5 but has two intermediate vertical walls 21g / 21h perpendicular to the flat parts 21b / 21c of lten- veloppe and which divides it into three compartments, in each of which is mounted a flat or concave bottom 2/2/2 similar to that 22 which
567 has just been described with reference to said Figures 2 to 5. The seal between the vertical walls of the compartments and said bottoms is obtained as previously by means of lip seals 29/30/31 and the bottoms are positioned in the envelope by double-acting cylinders 32/33/34.

 The examples given in FIGS. 10 to 13 are not limiting, the container not being limited to two or three compartments but may include any number of them.

 Figures 6 to 9 illustrate other embodiments of the container according to the invention.

 Figures 6 and 8 show a container 35 having an envelope 35a and a bottom 35b similar and mounted in the same way as the envelope 21 and the bottom 22 of the container described with reference to Figures 2 to 5. However, depending on the mode of embodiment shown in Figures 6 and 8, the container (the casing 35a and the bottom 35b) is bent in the direction of its length at right angles and thus comprises two rectilinear parts 35c / 35d connected to each other by curved parts 35eJ35f, the container thus adopting the general shape of an L.

 FIGS. 7 and 9 show a container 36 comprising a similar envelope 36a and a bottom 36b and mounted in the same way as the envelope 21 and the bottom 22 of the container described with reference to FIGS. 2 to 5.

 According to the embodiment illustrated in FIGS. 7 and 9, the container (the envelope 36a and the bottom 36b) is bent twice at right angles in the direction of its length and thus comprises two rectilinear parts parallel to each other 36c / 36d connected by curved parts 36e / 36f / 36g / 36h to another rectilinear part 36j perpendicular to said rectilinear parts 36c / 36d, the container adopting the general shape of a U.

 The use of such 35/36 containers and of a deformable sheath of crepe paper, polyethylene or fabric, make it possible to directly produce blocks or strips of foam of desired shape usable without any cutting or with a simplified cutting.

 The examples described with reference to Figures 6 to 9 are not limiting, the container according to the invention can take any other form.

Claims (13)

 1. Device for producing blocks of polymer foam from a mixture of liquid reactants, comprising a container (2) the bottom of which comprises at least one orifice (22f) for admitting said reactants and means for unwinding at least a flexible strip or sheath (4) for tightly surrounding the container (2), characterized in that it comprises  - an envelope (il) constituted by at least one vertical wall (21b / 21c / 21d / 21e) of a closed contour delimiting at least one compartment;  - A bottom (22) disposed inside said compartment (21) whose edge which delimits it (22a / 22b / 22c / 22d) extends parallel and close to the internal face of the wall (21b / 21c / 21d / 21e) of said compartment;  - Means (15) for sealing between said bottom (22) and said wall (21b / 21c / 21d / 21e);  - Means (20) for causing the relative displacement of said bottom (22) and said envelope (21) to vary the volume of the container and position the bottom (22) relative to the upper edge of the envelope (21) and ,  - Means (23/24) for applying said strip or said flexible sheath (4) against said envelope (21).  2. Device according to claim 1, characterized in that the container (2) is of an elongated shape and has rounded lateral sides (21d / 21e).  3. Device according to claim 2, characterized in that the container (35/36) is bent at least once in the direction of its length.  4. Device according to any one of claims 1 to 3, characterized in that said envelope (21) comprises at least one additional separating wall (21f) extending longitudinally and which divides it into at least two compartments in each of which is disposed a background (23/24).  5. Device according to any one of claims 1 to 3, characterized in that said envelope (21) comprises at least one additional separating wall (21g / 21h) extending transversely which divides it into at least two compartments in each of which is arranged a bottom (25/26/27).  6. Device according to any one of claims 1 to 5, characterized in that the bottom (22/23/24/25/26/27 / 35b / 36b) which is arranged in each of said compartments, is concave and shaped rounded.  7. Device according to claim 6, characterized in that said bottom (22 / 35b / 36b) is of a cross section of a generally semi-cylindrical shape.  8. Device according to any one of claims 1 to 7, characterized in that the envelope (2î) comprises, around its upper edge, a flexible seal (22) on which the strip or the flexible sheath (4) is in support.  9. Device according to any one of claims 1 to 8, characterized in that said envelope (21) is fixed and that the variations in altitude of the bottom (22/23/24 / ...) in the envelope ( 21) are obtained by double-acting cylinders (20)  10. Device according to any one of claims 1 to 9, characterized in that it comprises on the periphery of the edge of ltenve- loppe (21) which comprises the flexible seal (22) at least one support member (23 / 24) of the flexible strip or sheath (4) on said seal (22).  11. Device according to claim 10, characterized in that it comprises, around the edge of the envelope which comprises said flexible seal (22) two support cylinders (23/24) of the strip or of the flexible sheath ( 4) on said joint, which cylinders are parallel to each other and to the longitudinal edges (21b / 21c) of the envelope (Z1) and are mounted for rotation about two axes located at said upper edge of the envelope.  12. Device according to claim 11, characterized in that the cylinders (23/24) have flared ends in the shape of a flag (23a / 23b-24a / 24b) parallel to the rounded ends (21d / 21e) of the envelope for press the strip or flexible sheath (4) against the seal (22) which extends around the periphery of the upper edge of the envelope (21).  13. Device according to claim 1, characterized in that the bottom (22/23/24 ...) comprises, on its periphery, a flexible seal (15) brought into contact with the internal face of the wall of said compartment to achieve 11 sealing between said bottom and said compartment.