Method and double conveyor for the continuous production of laminated foam sheets

The invention relates to a method and a double conveyor belt for continuously producing laminated with outer layers of foam webs, wherein an upper layer and a lower outer layer as well as a meshwork web are introduced into the Schäumraum of a double conveyor belt and spread on the bottom outer layer prior to entry into the Schämraum a flowable reaction mixture is penetrating through the mesh sheet during expansion on passing through the Schäumraumes and bonded to the outer layers.

Here polyurethane foams, polyisocyanurate foams, phenolic resin foam, or the like are generated; whichever starting components are used for the flowable reaction mixture from which forms the foam. It is generally known, facings back covered with batts or webs together with reinforcement such as glass cloth, to break in the Schäumraum. This is to the mechanical strength, in particular immediately below the cover layers is increased, a better connection of the cover layers obtained with the foam core in the foam and a decreasing density profile of the outer layers towards the center can be generated. The latter applies in particular when using non-woven fabrics. These additional paths thus serve essentially the gain. Accordingly, they have a small mesh size or a high grammage and made of high quality material, preferably glass fibers. The collective term "mesh webs" are to be understood here sheets of woven, knitted, latticework and, more broadly, non-woven fabrics.

It has been found that, to accumulate in the surface layers to be processed, which are only slightly or not permeable to gas below the upper outer layer during foaming more or less large gas bubbles. These are distinguished in thin, sheet-like layers later from their viewing area. These irregular bulges are not just a blemish. Because these points are hollow, lies precisely here increased risk of damage to the outer layer with adverse consequences. When using the previously customary mesh webs, especially glass fiber woven and nonwoven fabrics, it has been found that also the formation of gas bubbles could not be avoided. Depending on the nature of these tracks came before it, that places these tracks have no foam, ie that the gas bubbles for walking through the lanes; or within a track, the reaction mixture was further evident crawled through capillary action and has formed a Schaumstoffilm, were under any gas bubbles present. In the latter case, although the Schaumstoffilm velvet backing sheet has stabilized the covering layer at this point something; under shock or strong stresses on these voids is also the danger of damage. In the above-described method, these bubbling occurred only below the upper outer layer. obviously during the reaction of the chemical system being formed and trapped gases when applying air bubbles have enough time to rise within the foaming reaction mixture and to reach the surface or in the vicinity thereof, before it is cured.

There is therefore the task of improving the initially described method and the conveyor belt so that laminated with layers foam webs are free of bubbles below the upper outer layer.

This object is achieved in that a meshwork web is used whose adjacent nodes at a distance of 3-15 mm among themselves display while both the maximum height and the maximum width of the ridges of the netting be between 0.1-2.5 mm, said meshwork web is allowed to run in at a distance of 0-15 mm from the upper outer layer.

the spacing of the nodes about 4-10 mm, height and width or diameter of the webs 1.5-2 mm and the spacing of the meshwork web is about 4 to 10 mm preferably.

It has surprisingly been found that the intended purpose to be fully met by using such a meshwork web opposite of the aforementioned reinforcing webs. It should again be noted that is meant by the term "mesh web" woven, knitted, latticework and, more broadly, non-woven fabrics. It must be fulfilled only the parameters. Since no definable mesh sizes are available in batts, the overwhelming majority of the openings of such a nonwoven fabric in accordance with the distances between adjacent nodes should size of 9-225 mm² exhibit. Obviously, the mesh size of a decisive influence. If it is too small, the desired effect is no more a as if the mesh size is too large. The same applies to the cross-sectional dimensions of the webs of the netting. You obviously need to have a certain width and height or diameter, in order to ensure that even in the top layer, the gases are not encapsulated in the individual stitches when represents meshwork web concern, but can escape. As a material for such a mesh webs are any materials previously used for reinforcing webs, such as mineral fibers, especially glass fibers, metal fibers or wires, synthetic fibers or wires, carbon fibers and natural fibers such as sisal, jute or hemp, and paper fibers. It is understood that a meshwork web can also contain various dene such materials. In particular, it is also possible to provide along the width of the web of different sizes or meshes of different strength webs (threads, wires) to be arranged.

Preferably a meshwork web is used from inferior materials.

Especially the use of mesh sheets of such inexpensive materials makes the new process interesting. For the production of mesh webs to provide particular waste or regenerated materials, especially such plastics at. It is understood that even high-quality materials can be used, particularly when these meshwork web in addition to serve the gain.

According to a particular embodiment of the meshwork web is allowed to enter, separated by the covering layer.

This form of implementation is the easiest and let themselves perform, as a rule at least two unwinding stations are provided for the upper outer layer to each have a spare roll in stock, while the other part runs the top layer to existing double conveyor belts without additional equipment. One could use a pulley block as supply station for the meshwork web so necessary.

Alternatively, it is of course possible to break in a prefabricated composite sheet as a cover layer and meshwork web.

This may consist in the simplest case of a wound together with a meshwork web coating layer, which roll accordingly arriving together. However, it can be a real composite web also by the mesh panel is connected to the outer layer, for example, at regular intervals over splices or optionally welds. Importantly, however, appear that the webs of the netting may abut the top layer only locally or in part, in order to ensure distribution of the gases below the top layer. Depending on the condition and connection between mesh sheet and cover layer and in particular thickness of the cover layer, the connection points on the top layer can emerge outside. If the distribution of the connecting points is regularly could even cause a decorative effect. By appropriate selection of the position of the connection points, this effect can be varied.

In another particular embodiment, a meshwork web is used which has at least partially lands (threads, wires) of stretchable material.

Such preferably elastic extensibility has the effect that the meshwork web undergoes vibration solely by their inward movement, and also by the problems caused by the revolving conveyor belts shocks, which is enhanced by the stretchability, thereby destroying the education begriffener gas bubbles is promoted.

In another particular embodiment, the meshwork web is mixed with the foaming reaction mixture in pulsation before contact.

In this way also the effect described above is to be achieved, namely that resulting from minimal relative movements of the stitching line gas bubbles are destroyed or their formation is avoided from the outset.

Preferably is left even at a distance from the lower outer layer enter such a meshwork web.

It has. been shown that even with the utilization of low-grade material for the stitching line this effect in the finished foam sheet below the top layer such stabilization that one can use those of lower basis weight in particular for roller facings. This effect is known from the use of prior art backing sheets ago, but it was not foreseeable for the use of the novel mesh web. This measure is of particular advantage if high quality coatings, such as aluminum foil, may be used. One can then lower their strength, for example, to the limit of admissibility. So far, film thicknesses were in use of about 50-80 μ. Instead, can now use films, down to half of the previously customary strengths. This of course applies equally to the upper outer layer. Thereby the rise in production by the additional meshwork web is not only balanced, but the production is beyond even cheaper.

Preferably at the beginning of Aufschäumprofils a shifting of the reaction mixture is maintained.

It has been found that certain chemical systems, especially PIR systems, have already lost significant portions of their bond strength due to their reaction behavior, before they come to the upper outer layer of frothing in touch. Until now it has such overrolls basically wanted to avoid because they on the one hand the risk include that air is taken, and the other one was always of the opinion that seen over the cross section, the age range of the reaction mixture should be as narrow as possible. Here, then, the opposite approach is taken, by trying by overrolls to increase the age range of the mixture. Thus, the adhesive effect is surprisingly increased again, and the other resulting in the shifting air pockets to be resolved by the use of the novel mesh paths again appear.

As already described, it requires to perform the method in the simplest case no change to the existing double conveyor belts.

If you want the mesh sheet at a distance from the upper outer layer and the upper conveyor belt introduce, as one proceeds from an upper conveyor belt and a lower conveyor belt which limit a Schäumraum wherein above the lower conveyor belt upstream a reaction mixture feed device is provided and supply stations for feeding are provided by layers and a mesh sheet.

The new thing is that there is arranged a spacer at the entrance of Schäumraums below the upper conveyor belt.

This is, for example, laterally mounted on the machine frame. It consists for example of a rail over which reciprocates the upper cover layer and below the hergleitet the meshwork web. It is understood that the mesh web are supplied either through a position of the roller bracket or by an auxiliary role so would have to abut from below against this rail. This track is for example for setting a different distance from a rail height of other replaceable or adjustable in a simple manner at an angle, whereby the angle changes according to the height. The axis of rotation must be positioned immediately below the lower run of the upper conveyor belt, so that the upper outer layer is not pinched. Since the channel may have only relatively small thickness corresponding to the desired distance, they would tend to sag in the usual working width of 1 m to 1.50 m in. But it will be supported by the mesh sheet. In addition, the rail can be supported by a but disposed underneath roller of larger diameter, wherein then the mesh sheet between roller and rail would guided.

However, precondition for this is that the remaining amount of Schäumraumes allows the arrangement of such a back-up roll.

However, the distance of the meshwork web arriving in the foaming reaction mixture can also be set that the spacer can be displaced in the direction of travel.

If you push the spacer closer to Aufschäumprofil so increases inevitably the inlet angle, thereby increasing the distance of the top layer. Proceeding away from it, the distance is smaller by the shallower angle of entry. It is understood that the meshwork web is pushed up by the foaming and solidifying reaction mixture slightly with, so that the inlet point in the Aufschäumprofil usually slightly lower than the later position of the mesh sheet below the top layer in the finished product. The choice of the inlet distance depends essentially on the rate of reaction of the chemical system or the Vorschubgeschwindikeit of the conveyor belt from.

According to a further embodiment the spacer is associated with a pulsator.

Although you can enable the mesh sheet by other means in position, however, the above solution is particularly useful, because here takes place the pulsation as close as possible prior to contact with the ascending Aufschäumprofil. According to the arrangement of the imbalance, the Pulsationsrichtung can choose. Preferred is a pulsation in the meshwork level, because this then exerts a saw-like effect on the foaming reaction mixture, destroying emerging bubbles. A cutting of the already solidified foam is not to be feared, because the movements are extremely low and the pulsation is quickly attenuated through which hardening foam.

In the drawing, the new laminator is shown purely schematically in an exemplary embodiment and described in more detail below. Show it:<ul><li>FIG. 1 the double conveyor belt from the side,</li><li>FIG. 2, the double conveyor belt facing the Schäumraum,</li><li>Fig. 3 is a plan view of a first embodiment of the meshwork web and</li><li>Fig. 4 is a plan view of a second embodiment of the meshwork web.</li></ul>

The double conveyor belt 1 comprises an upper conveyor belt 2 and a lower transport belt 3rd In between a Schäumraum 4 is included. It is bounded laterally by guide rails. 5 Above the lower conveyor belt 3 is arranged on the input side a reaction mixture charging device. 6 From an embodied as Rollenbock stock statin 7 running on the lower conveyor belt 3 a composite web 8 of a 40 μ thickness made of aluminum foil cap 9 and a mesh sheet 10 a. This meshwork web 10 consists of a metal mesh whose nodes 11 (FIG. 3) have a distance of 10 mm from each other and the webs 12 (wires) have a diameter of 0.5 mm. Under the upper conveyor band 2 runs as a cover layer 13 is also an aluminum foil of the type described above. It is withdrawn from a supply station configured as Rollenlagerrung 14 and guided over a deflection roller 15th Over the same guide roller 15 is also formed as a roller bearing supply station 16 a meshwork web 17 (FIG. 4) introduced. It consists of plastics latticework which has been produced from waste polyethylene. The webs 18 (wires) this gridwork have rectangular cross-section and a height of 1.0 mm, while its width is only 0.5 mm. At the nodes 19, the intersecting webs 18 are welded together. The distance between the hubs 19 from each other is in the axial direction of mesh sheet 17 mm 3 and transversely to 10 mm. The upper cover layer 13 is guided between the upper conveyor belt 2 arranged thereon and a spacer 20th This spacer 20 consists of a rail 21, which is mounted by means of axle journals 22 rotatably on the machine frame 23rd The mesh sheet 17 is guided by the rail 21 side of this fitting (but for the sake of greater clarity by far shown). By turning the rail 21, the distance of the mesh sheet 17 of the upper cover layer 13 can change when immersed in the rising foaming profile 24th One of the journal 22 is coupled to a mounted on the machine frame 23 pulsator 25, which transversely offset with a frequency of 30 Hz, the rail 21 to the direction of the lead. The double conveyor belt 1 operates at a feed rate of 6 m / min. The thickness of the manufactured laminated foam sheet 26 is 40 mm. At the beginning of Schäumprofils 26, the reaction mixture forms a bead-shifting 27, whereby older mixed with younger reaction mixture.