AT404366B - MINERAL WOOL FELT - Google Patents

Description

ΑΤ 404 366 Β

The invention relates to a felt made from crimped mineral wool, which can be bent temporarily or permanently and has a surface film, in particular one based on paper, at least on its side provided as a convex surface.

A glass fiber mat that is covered on one side with a film, e.g. is made of paper, GB-A-1 414 596 can be removed; however, there is no further information about the glass fiber mat or the film.

Under crimped mineral wool felt or " crimped felt " In the following, a felt is understood in which the orientation of the fibers is quasi-random instead of being parallel in one plane.

Crimp felts are intended for various applications, especially if you want to be able to either exert a pressure without too much compression or a pull acting perpendicular to the surface without peeling. Accordingly, they are very sensitive to bending in contrast to conventional layered felts and as soon as you bend them yourself, they break perpendicular to their surface. This fact significantly limits the field of application of the crimped felts that one wishes to be able to expand.

Traditionally, felts are layered from mineral fibers and are made by continuously depositing the fibers transported by gas streams on a conveyor that retains the fibers and allows the gas to pass through.

Before laying on the conveyor, the fibers are coated with a resin mass, which is used to bind the fibers together and thus gives the felt formed its cohesion. The resin composition applied in the liquid state is crosslinked by a heat treatment which acts on the felt previously brought to the desired thickness and specific composition.

The conventional types of felt formation lead to products whose properties do not fully meet all the requirements for certain special applications. In addition, the required insulating properties generally make it necessary for the products used to show very specific mechanical properties. This is e.g. the case when the products carry masonry elements and, as a result, they have to withstand pressure forces in such a way that they serve as insulation for ventilated terrace roof coverings. This is also the case if the products are used for external insulation and must therefore be able to withstand pull-out forces in particular.

In order to achieve products that show these special properties, it is necessary to change the conventional methods of felt production.

In conventional processes, the formation of felt by depositing the fibers on a conveyor or on an analog organ leads to a tangled fiber layer which is not homogeneous in any direction. It has been found experimentally that the fibers have a strong tendency to lie parallel to the receiving surface. The longer the fibers are, the greater this tendency. This felt structure is favorable for its insulating properties and its tensile strength in the longitudinal direction. Hence, such a structure is advantageous for numerous applications. Accordingly, it is understood that such a structure e.g. is not ideally suited for a product that is to be pressure-tested or squeezed in its thickness direction.

Methods are known with which a quasi-random orientation of the fibers can be achieved. European patent application EP-A-0 1 33 083 proposes that the felt made of fibers deposited on a receiving member, possibly after exerting pressure in the direction of its thickness, be passed lengthwise by passing it through a pair of conveyors which are driven at a certain speed. and continuously compacting a pair of conveyors driven at a lower speed than the aforementioned. A higher degree of compaction can be achieved if the compaction is carried out in several successive steps, particularly in the case of felts where the compaction is very difficult to achieve without wrinkling. Likewise, the properties of the products obtained can be improved for an equal final dimension of the compression if the compression is carried out in several steps.

Another document, European patent application EP-A-0 434 536, proposes a mineral fiber felt with improved properties in which the fibers have a quasi-random orientation and which is formed from fibers which are predominantly between 2.5 and 2.5 in diameter and 4.5um, have a length of 2 to 15 cm and a specific mass not exceeding 40 kg / m3. In this application it is contemplated that the mat may show surface finishing, i.e. can be coated with one or two adhesive films made of paper, aluminum, polyethylene or PVC.

The crimped mineral fiber mats obtained by the methods described are generally transported and used in the form in which they were made, i.e. as flat tracks. It would therefore be interesting to be able to bend curling mats temporarily or permanently, if necessary with a small radius of curvature.

The need to be able to roll up curling mats of considerable length in order to enable transport and storage without taking up too much space is evident. In the field of industrial 2

AT 404 366 B

Use of the ruffling mat is the insulation of large sewers or cylindrical cisterns that must be accessible, an application in which the permanent curvature of a ruffling mat would be very useful.

Again in the field of the prior art of mineral wool crimp felts, EP-B-0 472 532 is known, which proposes a method for producing a crimped sheet which is coated on one side with a foil. According to this method, according to the conventional crimping method, a glass fabric is placed on both sides of the mat before heat treatment of the resin forming the wool is carried out. At the end the mat is divided in thickness to obtain two identical mats coated on one side. This process enables the creation of a panel that can be arched, leaving the glass fabric on the concave side. The document clearly shows that bending in the other direction (the glass fabric on the convex side) is impossible. In fact, the intermediate with the fabric on both sides is described as stiff, but after separation the fibers on the free side "towards the fibers are not subjected to tensile and compressive forces when the sheet is bent, but perpendicular to the fibers . Because the sheet made with the process bends well backwards due to the lack of a horizontal bandage. &Quot; The comparison of the two phenomena, namely the stiffness of the panel covered on both sides and the flexibility of the panel cut in the middle, shows that the glass fabric is undeformable when pulled and that it cannot be bent if the covering is on the concave side. The assembly method described in the document, whereby the edges of the ceiling panel "are based on T-profits", as in the case of a vault, confirms this.

The invention has set itself the task of creating a product, a mat made of crimped fibers, which can be rolled up without damage in order to enable its transport and storage.

It is equally an object of the invention to enable the use of crimped mineral fiber mats on curved surfaces without sacrificing their properties, particularly that of

Lose insulation.

The goals set are achieved with a felt of the type mentioned at the outset in that, according to the invention, the bursting resistance of the surface film is greater than 300 kPa.

In an advantageous development of the invention, the surface film can consist of kraft paper with a basis weight of more than or equal to 60 g / m 2.

In a preferred embodiment of the felt according to the invention, its degree of crimp is above 4 and its basis weight is below 2 kg / m 2 for easy curling and for preserving all of its properties after it has been used once on a curved surface.

An advantageous variant of the product according to the invention has fibers on the side opposite the surface film provided with the invention, which practically all run perpendicular to the surface. With such an arrangement it is ensured that if the felt of crimped mineral wool emerges in particular from the division over the thickness of a thicker felt, the opposite surface of which has been provided with a surface film according to the invention and has been separated.

The figures and the following description make it possible to understand the invention and to understand its advantages.

1 shows the result of the curvature exerted on a crimping mat according to the prior art, FIG. 2 shows a mat according to the invention before and FIG. 3 after a curvature.

The crimped felts in question are made from mineral wool, glass wool or rock wool. These products are very often made from fibers obtained by centrifuge processes according to which the passage through the openings of a centrifuge or simply by ejection onto the surface of a roller rotating at high speed is carried out.

The implementation of the fiber formation mainly comprises one or more machines of the previous type of fiber producers. The emitted fibers are collected at the lower part of the machine by suction onto a conveyor cloth, which forms the bottom of a receiving chamber.

Inside the chamber, devices radiate a liquid binder onto the fibers. Conventionally, this has been attempted in such a way that the binder distribution on the fibers is as uniform as possible so that the binder is then evenly distributed over the entire felt.

The felt exiting the chamber is usually relatively light. Its average specific mass is small with a considerable thickness. In addition, because of the way the felt is made, the fibers are mainly oriented in directions parallel to the conveyor.

In the conventional manufacturing plants for felts made of mineral fibers, the felt leaving the receiving chamber immediately enters a space for heat treatment, which is used to apply the binder 3

AT 404 366 B enables.

If, on the other hand, a crimped felt is produced, an additional operation is carried out before the binding agent is applied: this involves changing the main orientation of the fibers, whereby several methods are possible. 2 B. you can "edit" the felt with needles, through whose action the fibers are oriented perpendicular to the felt surface. Another method allows a very large increase in specific mass and a different fiber orientation to be imparted to the felt by a sequence of changes.

The changes according to the latter method preferably consist in a compression of the felt in the sense of the thickness. This compression is e.g. obtained by passing the felt between two conveyors, the distance between the two conveyors decreasing in the sense of advancing the felt.

The felt compressed in this way then passes between two pairs of conveyors, the speed of each pair being lower than that of the previous pair of conveyors, which causes the felt to be compressed longitudinally. During this sequence of changes, the felt is continually limited to prevent it from at least partially returning to its original volume and is then introduced directly into the heating chamber where the heat treatment ensures the crosslinking of the binder and the stability of the product.

If a sample of the crimped felt obtained according to one of the aforementioned methods is then subjected to a curvature, the product generally deteriorates even for very large radii of curvature. Cracks appear between the fibers on the convex side and propagate to the interior of the product. 1 shows a representation of this phenomenon. Such cracks destroy the lateral stability of the product and severely impair its cohesion. In fact, the break in the cohesion between the fibers on the one hand and the tear on the other hand is irreversible: i.e. the chemical compounds in the binder no longer exist due to its crosslinking.

The phenomenon to be described has the effect that it is impossible to temporarily curl a crimp felt without affecting its properties. This also if e.g. a crimped felt made of glass wool with a specific mass of 16 kg / m3 and a thickness of 120 mm is used to isolate a horizontally arranged cylindrical cistern of one meter in diameter - the use of the previous crimping material allows the realization of good continuous insulation - with cracks on the convex side occur, as shown in Fig. 1, which affect the thermal insulation of the ruffled felt jacket remarkably.

If you want to sell a crimped felt with a width of 1.20 m, a length of 10 m and a specific mass of 30 kg / m3 and a thickness of 30 mm in the same field, it is interesting that the product in to be able to bring the shape of a roll, the felt being rolled up. In such a case, even if the outer turns of the roll have a large radius of curvature, which only causes small depth cracks on the convex side, this differs from the center of the roll, where the radii of curvature are of the same order of magnitude as the felt thickness, therefore only with Trouble over 30 mm. The impairments are not acceptable there. Nevertheless, it is particularly interesting to roll the crimped felts, i.e. Can be stored on site with unlimited length, making it possible to cut a required section accurately without creating waste that is wasteful.

The inventors therefore had the idea of equipping one side of the product with a surface film, the function of which is essentially to avoid an extension of the convex side of the product which is to be subjected to a curvature.

In tests with a number of different materials, plastic films (polyethylene), metals (aluminum) and various papers (Kraft) have been used. These were simple foils or composite materials. The latter appeared in the form of layer materials, such as an aluminum foil, which was coated on its entire surface with a polyethylene foil, u. in the form of a single reinforced film. Kraft papers reinforced with glass or polyester fiber reinforcement nets have also been tested.

As an example, a process is described below that allows a solution to the problem to be found. On a glass wool production line, where the fibers are obtained by spinning them through the openings of a centrifuge, between the crimped felt and the conveying cloth, which carries it before entering the heat treatment facility, where the crosslinking of the binder takes place, a surface film made of kraft paper with a basis weight of 90 g / m2 is inserted. This is glued to the felt in the treatment area and remains on it permanently; the 4th

Claims (3)

The product obtained from AT 404 366 B is shown in FIG. 2. The felt had a specific mass of 43 kg / m3 and a thickness of 60 mm. Its degree of curl, i.e. the longitudinal concentration of fibers obtained by the crimping process was 4.5 (this is the ratio of the velocities at the entrance and exit of the crimping zone; it is also the increase in the specific mass). When trying to roll up the felt equipped in this way, care was taken to ensure that the kraft paper was on the convex side. After the roll had been held taut for a week, it was brought back to a flat state and it was found that the felt, once flat, showed no memory, i.e. once leveled maintains its flatness. Finally, a destructive test, in which the kraft paper was detached from the felt surface, showed no cracks; the product did not undergo any changes when rolled up. A tentative curl in the other sense, with the paper on the concave side, gave the felt according to FIG. 1 several to half the felt thickness and in several places through-and-through cracks. In contrast, when the paper was on the convex side, the result was that shown in Fig. 3, from which it can be seen that the felt was compressed only on the concave side. A comparison test with the same paper but a lighter basis weight (60 kg / m3) led to a failure; in the course of rolling in the felt, it is torn in several places. Continued studies with various materials for the surface film have finally shown that the condition necessary for good results of the invention was that the burst resistance of the film should be above a certain threshold: 300 kPA. It has emerged in a completely surprising way that this limit value is independent of the properties of the felt; as soon as the degree of crimp is above 4, the felt, regardless of its thickness or specific mass, can be subjected to severe curvatures until it is rolled under the measure that the surface film is on the convex side and that its bursting resistance exceeds 300 kPa. The burst resistance is a characteristic variable for the durability of thin films for packaging. The regulation must be observed in accordance with DIN standard 53 113 (June 1990). The only limits found are large felt thicknesses associated with large specific masses. The results are less certain because e.g. a felt of 60 kg / m3 has a thickness of 120 mm. It is therefore possible to bend a felt intended to insulate a curved base, but not to roll the felt in, leaving no space in the middle of the roll. It has been found that if the specific mass of the product multiplied by the thickness remains within certain limits, curling is possible at any time. If the product of specific mass in kg / m3 and the thickness in meters (i.e. the basis weight) is at most 2 kg / m2, then the curling of the product according to the invention is always possible even with a degree of curl above 4. 1. Felt from crimped mineral wolves, which is temporarily or finally curvable and at least on its intended as a convex side surface film, especially one based on paper, characterized in that the bursting resistance of the surface film is greater than 300 kPA. 2. Felt according to claim 1, characterized in that the surface film is made of kraft paper with a basis weight above or equal to 60 kg / m3. 3. Felt according to claim 1 or 2, characterized in that its degree of curl is above 4 and its basis weight is below 2 kg / m2. With 1 sheet of drawings 5