SE507090C2 - Creped mineral wool blanket - Google Patents

Abstract

To permit the curvature of felts of crimped mineral wool fibres, ie. those in which the orientation of the fibres, instead of being parallel to a plane, is quasi-random, in a temporary or permanent manner, they are provided on the convex side with a surfacing sheet, the rupture resistance of which is greater than 300 kPa such as, for example, a kraft paper of a surface mass which is greater than 60 g/m<2>. <IMAGE>

Description

507 10 15 20 25 30 35 090 2 products used for external insulation and which, above all, must be able to withstand tensile forces.

In order to produce products which exhibit special properties, the traditional procedures for the production of tarltar must be modified.

In the traditional method of production, the fibers are formed by depositing the fibers on the receiving conveyor or some similar means, which leads to a mixture which is not homogeneous in all directions. Experimentally, it can be stated that the ñbres have a strong tendency to place themselves parallel to the receiving surface. This tendency is more pronounced the longer the fibers are. This structure of the altars is favorable for the insulating properties of the altars as well as for their resistance to tensile stress in the longitudinal direction. For a large number of areas of use, such a structure is consequently advantageous. It is to be understood, however, that this construction is not the most suitable when the product should be resistant to compression or elongation in the deep joint direction of the product.

Methods are known which give a virtually random direction or orientation of the ñbres. In this respect, reference is made to European patent application EP-AO 133 083, which proposes that the belt collected on the receiving means, possibly after being subjected to a deep compression, be continuously compressed in the longitudinal direction by passing from a pair of conveyors driven at a certain speed to a pair of conveyors whose speed is less than the previous one. Higher compaction rates can be achieved when the compression is carried out in fl your successive steps, especially with blankets in which compression without creasing is most difficult to achieve. For the same degree of final compression, the properties of the products obtained can also be improved when the compression is carried out in fl your steps.

According to another publication, EP-AO 434 536, an avlt of mineral fibers is proposed with improved properties where the fibers have almost random directions and which consist of fibers, which for the most part have a diameter between 2.5 and 4.5 μm and a length between 2 and 15 cm and a density not exceeding 40 kg / m3. According to this publication, the carpet can have a surface coating, ie be clad with one or two adhesive sheets of paper, aluminum, polyethylene or PVC. The mats of creped mineral fibers produced by the techniques just described are generally transported and used in the form in which they are produced, i.e. as flat sheets. However, it would be interesting to be able to temporarily or denitively bend or bend the creped carpets, possibly even with small radii of curvature.

Being able to roll up creped carpets to be able to transport and store considerable lengths without this requiring too much space is of course of great interest. In the industrial use of creped carpets, insulation of large piping systems or cylindrical cisterns, on which one must be able to walk, are examples of applications in which permanent curvature of a creped carpet would be very useful.

In the field of prior art with respect to creped mineral wool salts, the publication EP-B-0 472 532 is also known, which proposes a technique for producing a creped board which is covered with a coating sheet on only one side. According to this procedure, after the creping procedure is laid down in a conventional manner, a glass cloth is laid on both sides of the carpet before a protective treatment of the resin which is to form the binder is carried out. At the exit, the carpet is split in depth, so that you get two identical carpets that are coated on only one side. By means of this technique it is possible to produce a plate which can be bent by the glass fabric side remaining concave. The publication makes it quite clear that bending in the other direction (glass tissue side convex) is impossible. In fact, the intermediate product with the fabric on both sides is described as being rigid, but after cutting, the fibers on the free side are “not exposed to tensile and compressive forces in the när direction when the board is bent, but perpendicular to the fi fibers. The disc produced by the process can be easily bent as a result of the absence of horizontal bonds on the back ”. A compilation of these two phenomena, rigidity of the disc lined on both sides and flexibility of the thickness-split disc shows that it is at tensile stress that the glass fabric is undeformable and that bending can only be achieved with the surface coating on the concave side. The mounting technique described in the publication in question with the edges of the roof panel "in abutment against T-sections" as well as at an arch confirms this. iso? The invention has for its object to provide a product, a carpet of creped fi bres, which without being destroyed can be rolled up around itself into a roll so that it can be transported and stored. It is also an object of the invention to make it possible to use carpets of creped minerals on curved surfaces without losing their effect, above all as insulation.

In order to achieve these results, the invention proposes a felt of creped mineral wool which is provided on at least one side with a coating sheet and is intended to withstand temporary or definitive bending, the one of its surfaces which is intended to form the convex surface, is provided with a coating sheet, the rupture resistance or breaking strength of which exceeds 300 kPa.

The sheet is suitably based on kraft paper. To achieve the required breaking strength alone, the sheet must have a basis weight in excess of or equal to 60 g / m2.

In order to be able to be easily rolled up around itself into a roll and to preserve its performance once it has been applied to a curved surface, the creped blanket according to the invention preferably has a creping number between 4 and 5 and a basis weight of less than 2 kg / m2.

According to an advantageous modification of the product according to the invention, on the side facing away from the one covered with the coating sheet according to the invention, it has fibers which are almost all perpendicular to the surface. Such a position is ensured if the creped mineral wool salt is a consequence above all of the division in the deep direction of a thicker felt, the side facing away from the side covered with the coating sheet according to the invention being formed at the cut.

The following description and drawing figures enable a better understanding of the invention and the advantages associated therewith.

In the drawing figures, Fig. 1 shows the result of a bending carried out on a creped mat according to prior art, 2 g 2 a mat according to the invention before bending and Fig. 3 after bending.

The blankets in question are made of mineral wool, glass wool or rock wool. Most often, the products are made from fibers obtained by centrifugation techniques, either by passage through the openings of the centrifuge or simply by ejection from the surface of a high-speed rotating disk. 10 15 20 25 30 35 Felt production facilities mainly comprise one or ang your machines of the type specified above for fiber production. The thrown-out fibers are collected at the bottom of the machines by suction on a belt conveyor which forms the bottom of a receiving chamber.

A special binder is sprayed on the interior of the chamber by means of special devices. Usually, an attempt is made to obtain as even a distribution of the binder on the fiber as possible so that the binder will then be homogeneously distributed throughout the whole.

The blanket is usually relatively light when leaving the chamber. Its average density is small in relation to its considerable thickness. As a result of the production method of the oil, the fibers are mainly directed in directions parallel to the conveyor.

In traditional mineral preparation plants, the felt is introduced when it leaves the receiving chamber immediately into a heat treatment chamber for curing the binder. On the other hand, in the production of creped felt, an extra step is carried out before the binder hardens, when it comes to the dominant direction of the modes. Several methods are possible. Thus, for example, one can "process" the felt with needles, which through their movement direct the fibers perpendicular to the surface of the oil. By means of another method, a number of changes can be given to the felt a considerably greater density and a different direction.

The modifications according to this latter method preferably comprise compression of the felt in depth. The compression is achieved, for example, by allowing the oil to pass between two conveyors so arranged that the distance between two conveyors decreases in the feed direction of the oil.

The felt thus compressed is then allowed to pass between other pairs of conveyors and the speed of each pair is less than the speed of the previous pair of conveyors, giving rise to a continuous, longitudinal compression of the felt.

During this series of modifications, the blanket is constantly closed to prevent it from at least partially regaining its original volume and then being introduced directly into the heating cabinet, where the heat treatment ensures crosslinking of the binder and stabilization of the product. snv 090 6 10 15 20 25 30 35 When a sample of the felt thus prepared in accordance with any of the stated methods is bent for bending, a deterioration of the product is generally obtained, even at very large radii of curvature. Cracking occurs between the fibers on the convex side, which propagate to the interior of the product. Fig. 1 is an illustration of this phenomenon. These cracks impair the lateral stability of the product and severely impair its cohesion. The interruption in the connection between the fi bridges on either side of the crack formation is irreversible, as the chemical bonds established in the binder during its crosslinking no longer exist.

The phenomenon that has just been described has the consequence that a creped blanket cannot be bent, not even temporarily, without its properties deteriorating. For example, if using a creped fi lt of glass wool with a density of 16 kg / m3 and a thickness of 120 mm to insulate a cylindrical cistern with a diameter of 1 m and placed horizontally - the use of creped material should make it possible to provide good continuous insulation - cracks will appear on the convex side similar to those shown in lig 1, which significantly impairs the thermal insulation ability of the creped t lt sheath.

When you want to market a creped ñlt with a width of 1.2 m in lengths of 10 m with a density of 30 kg / m3 and a thickness of 30 mm, it is according to the same thinking to be able to package the product with the felt that is rolled up in the form of rolls. Although in such a case the outer winding turn of the roll has a large radius of curvature which gives rise only to cracks with little depth on the convex side, it is different at the middle of the roll, where the radii of curvature are of the same order of magnitude as the thickness of the felt and therefore hardly exceeds 30 mm. Here the deterioration becomes unacceptable. However, it would be of great value to have at your disposal creped eggs in roll form, ie with an unlimited length, since it is then possible to cut to the exact piece needed at the workplace without the formation of residues, which constitutes waste.

The authors then got the idea to provide one of the sides of the product with a surface sheet, the main function of which is to avoid stretching the convex side of the product which is subjected to bending.

Numerous experiments with different materials have been carried out, using plastics (polyethylene), metals (aluminum) and various papules in 507 san press qualities (power). Either simple films or composite materials were used. The latter constitute sandwich constructions, for example an aluminum film which, in addition to its entire surface, is connected to a polyethylene film, or has the shape of a single reinforced film. Kraft paper has also been tested, which is reinforced by means of reinforcement mesh of glass threads or polyester threads.

As an example, a method by means of which a solution to the problem posed will be described in the following. On a glass wool production line, where the fibers are obtained by pressing them through the openings in a Centrifuge, a capping sheet of kraft paper with a basis weight of 90 g is coated between the creped blanket and the carrier support mat before entering the heat treatment plant. / m2. This is glued to the felt in the treatment room and is included with it permanently, whereby you get the product shown in fi g 2. The product had a density of 43 kg / m3 and a thickness of 60 mm. Its creping rate, ie the longitudinal ñber concentration achieved at the creping moment, was 4.5 (which is also the ratio between the velocities at the entrance and exit of the creping zone and it also constitutes the increase in the density achieved). Attempts have been made with an filt equipped in this way and rolled around itself into a roll shape, ensuring that the force layer was on the convex side. After the roll had been kept in a tightly packed condition for a week, it was laid out flat and it could then be stated that once the blanket was laid out in a flat state, it did not return to a bent state, but once flattened it retained its flatness. A subsequent examination, during which the kraft paper was separated from the surface of the blanket, showed that no cracking occurred: the product had thus not been altered in any way by being formed into a roll.

An experimental roll in the opposite direction, with the paper on the concave side, gives an t lt with the same appearance as in fi g 1 with a large number of cracks which, in view of the moderate thickness of the fi lt, extend across it, from one side to the other in several places .

A507 10 15 20 25 30 On the other hand, when the paper was on the convex side, the result was that shown in fi g 3, from which the drawing fi shows that the felt was subjected to compression only on the concave side.

A comparative experiment carried out with an identical paper but with a smaller basis weight (60 g / m2) resulted in a failure when during the winding of the blanket the paper was torn in fl your places.

Studies carried out with different materials regarding the surface sheet have finally shown that an essential requirement for good function is that the sheet's resistance to rupture exceeds a certain threshold value, namely 300 kPa. In a very surprising way, it was found that this limit was not due to the properties of the oil. At the moment when the creping number exceeds 4, regardless of the thickness or density of the ñlt, it may be subjected to strong bending so that it can be rolled up around itself, provided that the surface sheet is placed on the convex side and has a breaking strength exceeding 300 kPa.

The breaking strength is a quantity that characterizes the strength of thin films intended for packaging. The measurement is carried out in accordance with the standard DIN 53 113 (June 1990).

The only limits that have been found are the considerable thicknesses of blankets with high density values. The results become less certain when, for example, a blanket of 60 kg / m3 has a thickness of 120 mm. It is still possible to give an ñlt, which is intended to insulate a curved surface, a curvature, but to roll up the blanket around itself in the form of a roll without the roll having a hollow empty center is impossible. It has been found that as long as the density of the product multiplied by the thickness remained within certain limits, it was still possible to shape it into a roll. If the density in kg / m3 multiplied by the thickness in meters (ie basis weight) stops at a maximum of 2 kg / m2, it is always possible to shape the product according to the invention into a roll even at a creping number exceeding 4.

Claims (5)

10 15 ¥ A 9 s sov 090 PATENTKRAV Creped mineral wool, which is provided on at least one side with a surface sheet and which felt is intended to be temporarily or definitively subjected to bending, characterized in that the side which is intended to be convex is provided with a surface sheets, the breaking strength of which exceeds 300 kPa. Mineral wool salt according to claim 1, characterized in that the surface sheet is based on kraft paper. Mineral wool salt according to claim 2, characterized in that the surface sheet consists of a kraft paper with a basis weight exceeding or amounting to 60 g / m2. Mineral wool enligt lt according to one of claims 1 to 3, characterized in that the creping number exceeds 4 and its basis weight is less than 2 kg / m2 and from the fact that the sig lt is rolled up around itself so that it forms a roll. Mineral wool salt according to one of the preceding claims. characterized by the fact that it hardens the side depth from the thicker felt.