NO327894B1 - Process for the preparation of a mineral wool product, in particular a mineral wool plate, and such a mineral wool product. - Google Patents

Abstract

The method envisages the manufacture of a board in which the fibre structure in a longitudinal section has been formed by means of crimping, the crimping of the fibres being obtained by means of conveyer belts operated at different speeds. <IMAGE>

Description

The present invention relates to a method for producing a mineral wool product, in particular a mineral wool plate according to the preamble of claim 1, and also relates to a mineral wool product, in particular a mineral wool plate according to the preamble of claim 6 below. The invention relates in particular to glass wool products and their manufacture.

Mineral wool products, especially when they are made of glass wool or stone wool, are mainly used for thermal insulation purposes, and more specifically for thermal insulation of buildings in areas such as roofs, walls and ceilings. For this purpose, mineral wool webs or mineral wool plates are laid between rafters or beams, and when necessary attached to the rafters or beams by means of stapling of protruding edges of aluminum linings. Alternatively, they can be inserted between the rafters and beams using a press fit, in which case it is not necessary to fix them mechanically.

However, thermal insulation of roofs and the like gives rise to problems due to the fact that very often the distance between the rafters or beams is not the same, but tends to vary even in one and the same building, so that it becomes necessary that the thermal insulation board or - the track to be introduced between the rafters or beams must be specially constructed or prepared for these different distances between the beams or rafters.

In this connection, it is known that thermal insulation webs, which are usually supplied in the form of rolls, can be produced and stocked in tightly graduated nominal widths, so that a suitable nominal width of the web material can always be selected according to the available distance between the rafters. However, this leads to corresponding waste of the casing. Furthermore, the necessity of making the lanes available in such graded nominal lanes requires that large quantities of individual products must be kept in stock, and this in itself entails a significant disadvantage.

A smart solution consists in using so-called creped filters, i.e. mineral wool webs with higher bending stiffness, which are rolled up under pressure at the production site to save space, and which on at least one of the large surfaces is provided with transverse markings in the form of bands or the like, which can be used as guidelines for cutting the track. Appropriate lengths of the mineral wool web can thereby be cut either along or parallel to these transverse markings, the length of the sections always being made equal to the free distance between the rafters plus a small surplus. The sections are thereby individually adapted to the rafters. Due to the greater bending stiffness, the cut sections after the web has been rolled out will always be available in sheet form, and this has led to the formation of the slogan "a sheet from a roll". The fact that the slightly too large mineral wool sections are placed with a press fit in the space between the rafters further ensures that the thermal insulation will be without openings even at the points where the plates rest against the rafters or beams.

US 5671518 discloses a process for treating mineral wool mats, comprising the steps of producing fibers, providing a binder, placing the fibers in the form of a laminar mat on a production line, and crimping the laminar mat by applying forces parallel to a surface of the laminar mat in a direction of movement of the laminar mat before the binder hardens.

WO 97/36034 shows a mineral wool product comprising layers of different density glued to each other.

There is also a need for alternative mineral wool products that can be used for thermal insulation between rafters or beams. The purpose of the invention is therefore to provide a mineral wool product which will not give rise to sheath waste and which is characterized by a carefully balanced relationship between flexibility and bending stiffness, the purpose being in particular to provide a method which makes it possible to adjust this relationship between flexibility and bending stiffness in a safe and simple way. The mineral wool board provided in this way should be easy to handle, ensure a wide range of possible uses due to the possibility of a quasi-inherent tolerance compensation, and should also be particularly suitable for fixing in the space between the rafters or beams when the buildings are to be insulated.

In particular, the invention should ensure a firm attachment of the mineral wool board and close contact with adjacent rafters or beams. Perfect thermal insulation also requires that the attachment is without thermal bridges.

According to the invention, this task is solved by the features specified in claim 1 as far as the method is concerned, while in the case of the mineral wool product it is solved by the features specified in claim 6.

Advantageous further developments of both the method and the mineral wool product are indicated in the respective independent claims.

According to the invention, the method for producing the mineral wool product according to the invention is characterized by the fact that, before hardening, at least one section that delimits one of the two main surfaces of the board or web is exposed to a so-called creping process, a form of crushing and stacking in the longitudinal direction . Due to this process, the fibers in this section tend to fold and assume an up-and-down pattern, while the fibers in the adjacent section overlying the former section mainly retain their original orientation, i.e. the fiber orientation in this section remains mainly parallel to the two main surfaces. The crimping process produces a higher density in the section that has been crimped, and this section will also be characterized by greater compressibility (a form of wrinkled zone), while the property of the adjacent layer or section that has not been crimped will not have been modified and therefore remain mainly as time-ligers. This forms the desired balance between flexibility and bending stiffness, a feature that is further accentuated by the increasing density that the crepe process provides.

For the purposes of the invention, it will be advantageous to subject only a single section to the creping process, in particular one of the sections which form one of the main surfaces and which extends the entire length of the plate or web.

The creasing process can advantageously be carried out with the help of conveyors which are arranged in a row and run at different speeds, and more precisely at gradually decreasing speeds. A form of ripple or wrinkle effect will thereby be achieved in the transition between adjacent conveyors which are operated at different speeds because the upstream conveyor will add more mineral wool than is taken away by its downstream counterpart. In this connection, it will be advantageous if the conveyor is arranged under the mineral wool web because in this case the specific weight of the lower section of the mineral wool web will expose it to the desired creping process in a very controlled manner. In principle, two conveyors driven at different speeds will be sufficient to enable the desired crimping process, but it would be better to arrange four such conveyors, and if necessary, more than four can also be arranged. Particularly advantageous is the use of endless belt conveyors. If necessary, one or more conveyors can be arranged above the conveyor unit, which is made up of conveyors with gradually decreasing speed, which will act almost as a counter team, in which case the creping process can be carried out by the conveyors in contact with the upper surface of the mineral wool web.

A uniform creep effect can be achieved when the conveyor tube velocities also decrease in a uniform manner. The greater the speed difference between successive conveyors, the stronger the creep process will be.

It would be appropriate for the speed of the fastest conveyor in the conveyor line to be approximately 20% greater than the speed of the curing oven, while the speed difference between successive conveyors should be of the order of 4%. The length of the carrying stretch of the conveyor row with decreasing speed can also be used as a control parameter for the shrinking process. The shorter the carrying distance is for these transporters, the more intense the creasing process and the resulting crazing structure will be. The thickness of the section with crushed fibers can likewise be determined by means of an appropriate choice of the length of the conveyor belt, but also of the distance between the conveyors.

The mineral wool product according to the invention, in particular the mineral wool sheet, is characterized by the fact that it contains at least two sections with different fiber orientations, and it would be advantageous if one of these sections delimits at least one of the sheet's main surfaces and if said section has a fiber structure that has been produced using a crepe process. It will also be advantageous for the mineral wool product if it consists of only two sections with different fiber orientation. In this case, the section which has been structured by means of the creping process may constitute up to 90% of the total product thickness, but usually its thickness will not exceed one third of this total thickness. In this way, the product can be given the desired carefully balanced ratio between flexibility and desired bending stiffness.

A preferred design example will now be described with the help of two figures, where

figure 1 shows the mineral wool plate according to the invention in its built-in position between two beams of a ceiling, and

Figure 2 shows a side view of a conveyor system to illustrate the manufacturing method according to the invention.

Both figures are purely schematic and not to scale.

As is common practice in the production of mineral wool, the mineral wool plate 1 shown in figure 1 is formed by cutting a certain length of mineral wool web which was produced by collecting mineral wool fibers on a conveyor belt, adding a binding agent and then passing the whole through an oven for thing. When a mineral wool web is formed in this way, it becomes mainly part of the fibers oriented parallel to the surface of the transport belt on which they are collected and are therefore parallel to the two main surfaces of the web. In Figure 1, the two main surfaces of the mineral wool board have been designated with the reference numbers 2 and 3.

As schematically shown in figure 1, the mineral wool plate 1 of the shown embodiment consists of two sections with different fiber arrangement or orientation, namely a section 4 which delimits or forms the upper main surface 2 of the plate 1, and a lower section 5 which delimits or forms the opposite main surface 3 of the plate 1. Due to the described method of manufacturing the web, the fibers in the upper section 4 are mainly parallel to the two main surfaces 2 and 3. The fibers in the lower section 5, on the other hand, are crimped and/or folded like a meandering river, a condition achieved by the creeping process to be described with reference to figure 2. It can be seen that the fibers in the lower section 5 are no longer substantially parallel to the main surfaces of the plate, the fibers instead of is characterized by an up-and-down pattern and by a limited parallel device, so that the structure can be generally described as a wave-like structure. Because of this fiber pattern, the flexibility of the plate 1 is rather greater than for a plate where all the fibers are mainly parallel to the main rafts. Due to the partial creping process, section 5 will also have a greater density, and this in turn constitutes an advantage in that it increases stiffness, a desirable feature that enables handling when the mineral wool board is to be introduced or pressed into the space between rafters or beams, and also has beneficial effects on the contact between the slab and the rafters or beams. The plate is therefore particularly suitable when the plate does not need to be self-supporting to maintain its position between the rafters or beams, but where the rafters or beams have some form of closure on the underside, for example a table covering, in which case the mineral wool plate 1 can be introduced from above.

In the design example illustrated in Figure 1, the upper section 5, which has been subjected to the further crimping treatment, and the lower section 4, which has not been subjected to this treatment, are of approximately the same thickness, so that the thickness of the upper section 4 and the thickness of the lower section is approximately 50% of the total thickness of the plate. However, it should be noted that the transition between the treated section 5 and the untreated section 4, where the fibers have remained substantially parallel to the main surfaces of the plate, is gradual, i.e. the transition from the wavy fibers in the treated section 5 to the parallel arrangement of the fibers in the untreated section 4 is not abrupt, but that the crimped and more or less wave-like up-and-down pattern of the fibers tends towards a flattening in the direction of the parallel device and constitutes a transition section, as roughly indicated in figure 1. The intensity of the crimping process can be regulated by suitably setting the functional parameters, and the crimping of the fibers can therefore be made more or less prominent.

For example, the mineral wool plate 1 shown in Figure 1, which can in particular be made of glass wool, has a length L (before installation) of 980 mm and a width of 600 mm. The thickness of the shown embodiment is 150 mm. However, these values can be freely chosen based on the application in question and must not be understood as limiting in any way. In reality, the dimensions of the plate or web can be chosen to suit the proposed application. As will be seen from a comparison between the plate as such (the upper part of the figure) and the plate in the built-in position (lower part of the figure), the plate 1 is made available in such a way that its length L is 980 mm, is slightly larger than the free opening between the rafters. When the plate 1 is to be built in, it is first compressed in the longitudinal direction and then pressed between the beams 6 of a ceiling 7, the free opening between the beams being 960 mm. This means that the plate is held in position between the beams 6 by means of the press fit caused by the elastic return force that builds up during the insertion operation. The excess length U is indicated in Figure 1 and in this particular case is approximately 2% of the plate 1 length L. When the plates are to be inserted between rafters or beams, it will usually be appropriate to work with excess lengths ti in the range between 1.5 and 5 %.

Figure 2 shows the usual conveyor belt 8 for transporting a web or mat 10 of mineral wool on its carrying section 9. This mineral wool web comes from the mineral wool production facility, and the adjustable calibration roller 10' is used to bring the web to the required thickness. As a general rule, the web will then pass over the two conveyors 11 and 12 in a curing oven, where the binder is hardened to form the finished mineral wool web.

In order to form the mineral wool sheet or web according to the present invention, however, at least two, and preferably four, additional conveyors 14-17 (as shown in the figure) must be provided before the curing oven 13, which conveyors are shown here as endless belt conveyors. These belt conveyors are here arranged below the mineral wool web 18 which is led to the curing oven 13, so that the mineral wool web 17 is carried on these conveyors 14-17 until just before it enters the curing oven 13. These conveyors are arranged close to each other, and each downstream conveyor, for example the conveyor 14 is driven at a lower speed than the immediately following upstream conveyor, here the conveyor 15. This means that the speed of the conveyors 17-14 gradually decreases from the conveyor 17 to the conveyor 14, and in the embodiment illustrated here the reduction from the conveyor 17 to the conveyor 14 effected in three identical steps. But such an equal reduction in speed from one carrier to the next is by no means mandatory. Instead, subsequent speed reductions can vary, however, so that the resulting differences in the crepe structure are as desired. In the design example shown here, if we set the transport speed of the conveyor to 100%, it will be suitable for conveyor 17 to operate at a speed of 116% and the three following conveyors with speeds of 112%, 108% and 104 respectively %. In this case, the conveyor 8 will operate at 120%, so that there will be advantageously five transitions between conveyors operating at different speeds. This will give the step-by-step crepe structure with the up-and-down pattern of the fibers shown and described in figure 1.

If necessary and as shown in figure 2, use can also be made of a conveyor 19 arranged above the mineral wool web and conveyors 14-17, or several such conveyors arranged in a row, but all these conveyors must be driven at the same speed if an impact on the essentially parallel alignment of the fibers in the upper section of the mineral wool web. Nevertheless, such upper conveyors can also be used to crimp the mineral wool web and thereby modify its fiber structure. But even when such upper conveyors are installed, the creping process can also be carried out without them, as all that needs to be done is to set them a certain distance from the upper surface of the mineral wool web carried by the conveyors 14-17. As will be seen, the method according to figure 2 can be used to produce an endless mineral wool web with a desired crepe structure in the lower section, although it is also entirely possible to produce webs or plates of limited length. However, it would be advantageous to produce an endless web, in which case the desired mineral wool sheets can be obtained by suitably cutting the web as it leaves the curing oven.

On the whole, the mineral wool product according to the invention makes it possible to provide thermal insulation between rafters and beams without wasting material because this product, due to the partial creping process to which it has been subjected, has a suitable wrinkled zone and can therefore compensate 1, 5 - 5% of the free distance between the rafters or beams without any problems. Finally, a small loss of so-called X, value as a result of the fiber arrangement caused by the crimping process will be compensated by the fact that the original gross density - which can lie in the range between 8 and 30 kg/m<3>, and especially between 15 and 20 kg/m<3> - is increased by approximately 0.5 kg/m<3> as a result of the crepe process.

Claims (13)

1. Method for the production of a mineral wool product, in particular a mineral wool plate (1), where the mineral wool fibers are collected on a conveyor belt while supplying a binder to form a plate (1) or a web (18), the arrangement of said fibers being substantially parallel to the two main surfaces (2, 3) of the plate (1) or web (18) or the collecting surface of the conveyor, and where the plate (1) or web (18) is then hardened, characterized in that only one of the two sections (4, 5) which delimits the main surfaces (2, 3) of the plate (1) or the web (18) is subjected to a creep process before hardening. 2. Method according to claim 1, characterized in that to start the crimping process, the plate (1) or web (18) is passed over at least two conveyors (14-17), preferably belt conveyors, which are operated at different speeds, each downstream conveyor (14) is operated at a lower speed than the immediately upstream conveyor (15). 3. Method according to claim 1 or 2, characterized in that four or five conveyors (14-17) are arranged in a row and run at different speeds. 4. Method according to one of the preceding claims, characterized in that the operating speeds of consecutive conveyors (14-17) are reduced evenly. 5. Method according to one of the preceding claims, characterized in that the operating speed of the fastest conveyor is approximately 20% greater than the speed of the belt conveyor (11, 12) of the curing oven (13). 6. Mineral wool product, in particular a mineral wool plate for thermal insulation of roofs, walls and ceilings, where the plate (1) consists of at least two sections (4, 5) with different fiber orientations, the sections (4, 5) with different fiber orientations extending parallel to two opposite main surfaces (2, 3) of the product or plate (1), and where one of the sections (5) limits one of the main surfaces (3) and the fibers in this section (5) are crimped and/or curled and/or form bends in the longitudinal direction, characterized in that the transition from one (5) of the at least two sections (4, 5) with different fiber orientation which is crimped, to the other (4) non-crimped section of the sections (4, 5) with different fiber orientation, is not stepwise, but proceeds gradually. 7. Mineral wool product according to claim 6, characterized in that the fibers in the section (4) which delimit the second main surface (2) are mainly aligned parallel to the plane of the main rafts (2, 3). 8. Mineral wool product according to claim 6 or claim 7, characterized in that the product only consists of two sections (4, 5) with different fiber orientation. 9. Mineral wool product according to one of claims 6 to 8, characterized in that the gross density is 8-30 kg/m<3>, preferably 15-20 kg/m<3>. 10. Mineral wool product according to one of claims 6 to 9, characterized in that the creped section (5) has a thickness of up to 90% of the total product thickness, preferably up to a third of said product thickness. 11. Mineral wool product according to one of claims 6 to 10, characterized in that the gross density of the crimped section (5) is approximately 6-8% greater than the gross density of the non-crimped section (4). 12. Mineral wool product according to one of claims 6 to 11, characterized in that the fiber orientation in the crimped section (5) is constituted by a predominant meandering or wave-like structure (fibers up and down in relation to the plane parallel to the two main surfaces). 13. Mineral wool product according to one of claims 6 to 12, characterized in that when the mineral wool board (1) is to be installed between rafters or beams, it is made available with a length that exceeds the free distance between the rafters or beams by between 1.5 and 5%, preferably 2%.