WO1996036778A1

WO1996036778A1 - Casing and underlying strip with diffusion apertures

Info

Publication number: WO1996036778A1
Application number: PCT/EP1995/001830
Authority: WO
Inventors: Gerhard Bauder
Original assignee: Paul Bauder Gmbh & Co.
Priority date: 1995-05-15
Filing date: 1995-05-15
Publication date: 1996-11-21

Abstract

In order to improve waterproofing of a casing and underlyaing strip with diffusion apertures comprising a bitumen-coated non-woven fabric while also preserving high water vapour permeability, it is proposed that the strip should comprise at least one first layer (1) of a melt-blown spun-bounded fabric consisting of fibres with a titre of between 0.04 and 0.7 dtex; and a second layer (2), joined over its entire surface to the first, of a spun-bonded fabric made from fibres a titre of more than 0.7 dtex, and that the second layer should be coated on the outside with between 15 and 70 g/m2 of bitumen (6).

Description

DIFFUSION-OPEN FORMWORK AND UNDERLAYER

The invention relates to a diffusion-open formwork and underlay with a bitumen coated fiber fleece.

Such formwork and underlay is known, for example, from EP 027750 B1. The water-impermeable and water vapor-permeable layer is realized in that a non-woven base is coated with a bituminous impregnating compound. This tears open on cooling and forms small openings through which water vapor can diffuse, while water cannot penetrate through these openings. To achieve this effect, for example, a bitumen amount in the

2 orders of magnitude from 250 to 300 g / m applied.

With such a structure it is possible to achieve a diffusion-equivalent air layer thickness S _^ between 10 m and 200 m, but much lower values would be desirable. This could be achieved in the known construction by using larger amounts of the impregnating compound in larger openings in the bituminous Impregnation mass layer arise. However, this would have the disadvantage that the underlay would no longer be watertight, so liquid water could pass through the layer.

It is an object of the invention to provide a generic formwork and underlay which is nevertheless fully secured against the passage of liquid water from the outside with significantly improved water vapor permeability.

This object is achieved according to the invention in a formwork and sarking membrane of the type described at the outset which is open to diffusion by virtue of the fact that it connects at least a first layer of a meltblown non-woven fabric made of fibers with a fiber titer between 0.04 and 0.7 dtex and one area with the first layer second layer of a nonwoven fabric made of fibers with a thread titer> 0.7 dtex and that this second layer on the outside with bitumen in a quantity

2 is coated between 15 and 70 g / m.

A multi-layer structure for the formwork and underlay is therefore proposed, in which a conventional fleece-shaped underlay is combined with a layer of a meltblown nonwoven with fibers, the fiber titer of which is significantly lower than that of conventional plastic nonwovens , so that this fleece contains fibers whose diameter is very small, for example in the order of magnitude between 2 and 8 μm. It has surprisingly been found that meltblown nonwovens of this type are very well permeable to water vapor, but that they have a high level of water resistance. A meltblown nonwoven achieves a water tightness in the order of magnitude between 10 cm and 50 cm (static pressure of a water column). This is a surprisingly high value, but it is usually not sufficient for use in underlayment and formwork sheets.

While the meltblown nonwovens have a high water resistance, they are not mechanically very stable. Only by combining such meltblown fiber nonwovens with conventional plastic nonwovens does a layer structure result that has the necessary mechanical stability properties.

In this layer structure, the outer layer, which is designed as a conventional plastic fleece layer, is coated with bitumen, but compared to the prior art with a bitumen amount that is considerably less.

In the EP 027750 B1 discussed at the beginning, bitumen

2 layers in the order of magnitude of 250 g / m and higher are described, with the new formwork and sarking membrane this amount of bitumen is only between 15 and

2 70 g / m. This leads to a substantially increased vapor permeability of the plastic fleece layer coated with bitumen in this way, but on the other hand this amount of bitumen is normally not sufficient to make the plastic fleece layer watertight.

It has now surprisingly been found that, despite this lack of tightness of the outer, conventional bitumen-coated plastic fleece layer, the layer structure of such a plastic fleece layer with a meltblown fleece layer to make it watertight leads, which is significantly higher than the waterproofness of the meltblown nonwoven layer alone and the conventional plastic nonwoven layer alone. The properties of the watertightness of the two plastic layers do not simply add up, but the combination of these two differently designed nonwoven layers results in a watertightness which is significantly higher than the sum of the watertightness of both nonwovens. The reason is not fully understood, but the waterproofness is probably favored by the non-polar character of bitumen, since this material is very difficult to wet with water.

In this way, a layer structure with surprisingly high water resistance is obtained, which is approximately 30 to 100% higher than the water resistance of the meltblown nonwoven layer alone. Nevertheless, this layer structure has a water vapor permeability that is still below a value of s ^ = 0.2 m.

It can be provided that the basis weight of the first

Location is between 10 and 75 g / m.

The weight per unit area of the pure plastic fleece of the second layer is preferably between 20 and 150 g / m.

In a preferred embodiment it is provided that the first layer is also connected flatly on the side opposite the second layer to a nonwoven fabric forming a third layer, the fibers of which have a fiber titer> 0.7 dtex. The first layer of the meltblown nonwoven is thus embedded between on both sides Layers of conventional non-woven plastic, so that the mechanically sensitive meltblown non-woven layer is mechanically protected. One of the outer layers is coated with bitumen in the manner indicated, the other remains without bitumen coating. Such a three-layer structure also has the described advantages of high water tightness on the one hand and high water vapor permeability on the other hand.

It is beneficial if the basis weight of the third layer

2 is between 20 and 150 g / m, the first and the third

Layers can otherwise be identical except for the bitumen coating.

It is preferably provided that the first layer is connected to the second and possibly the third layer by thermal welding.

In a preferred embodiment, the fiber titer of the fibers of the second and optionally the third layer can be greater than 2 dtex.

In a preferred embodiment it is provided that the bitumen coating of the second layer has alternately thinner and thicker coated areas. These can have the shape of parallel strips, for example.

It is provided that a maximum of 50% of the area of the second layer is coated thicker.

The second layer can be in the thicker coated areas

2 coated, for example, with 200 to 400 g / m bitumen his. It is advantageous if the thicker-coated areas of the second layer protrude beyond the thinner-coated ones.

This bitumen coating, which differs in some areas, affects the water vapor permeability comparatively little, but it enables safe walking on such a formwork and roofing membrane. This accessibility can be improved if the

Bitumen layer on the outside with a conventional synthetic

2 non-woven fabric is covered with a basis weight of 10 to 50 g / m 2, that is to say with a very thin non-woven fabric which practically does not impair the water vapor permeability.

In a preferred embodiment it is provided that the outside coating has self-adhesive properties at least in the edge area of the formwork and underlay and that this self-adhesive edge area is covered by a silicone-coated cover layer. This makes it possible to glue adjacent formwork and underlay sheets to each other in a self-adhesive manner and still maintain the water vapor permeability in this gluing area, since only the very thin bitumen coating described is provided in this gluing area. Surprisingly, however, it has been found that this very economical coating is also sufficient to produce such a reliable adhesive connection. It is advantageous if, when the bitumen layer is covered by means of a conventional non-woven fabric, this non-woven fabric is not led into the self-adhesive edge strip. With such a This formwork nonwoven covers the bitumen-coated surface of the web with the exception of the edge strip, and this edge strip is then covered by the silicone-coated layer which is released for laying.

In the case of an embodiment with thinner and thicker coated areas, this edge strip can preferably be extended over a number of such areas, so that the thick areas ensure reliable bonding, and preferably several times next to one another. It is advantageous if the areas extend as strips parallel to the edge.

The following description of a preferred embodiment serves in conjunction with the drawing for a more detailed explanation. The drawing shows a cross section through a preferred embodiment of a diffusion-open formwork and sarking membrane.

This comprises three layers connected to one another, namely a first layer 1 of a meltblown non-woven fabric, the one side with a second layer 2 of a conventional plastic non-woven fabric and on the opposite side with a third layer 3 also of a conventional plastic -Fiber fleece is covered. The layers 1, 2, 3 are connected to one another by welding, this connection can be made point-wise or over an area.

The first layer of the meltblown nonwoven stands out by a very low fiber titer in the order of magnitude between 0.04 and 0.7 dtex, ie these fibers have a very small diameter in the order of magnitude between 2 and 8 μm. The fibers can consist of various plastic materials, for example of polyester, polypropylene, polyethylene.

The basis weight of the first layer is between 10 and

75 g / m. This fiber layer is produced using the so-called melt-blown process. The melted thermoplastic materials are pressed in an extruder into a nozzle bar. The threads emerging from the nozzle bar are grasped by a hot air stream, drawn out in length and then deposited on a rotating sieve belt. In this way, nonwovens can be produced with very thin fibers, these fibers are considerably thinner than fibers of conventional plastic nonwovens, whose fiber titer is of the order of 4 dtex and above.

The layers 2 and 3 consist of such conventional plastic fiber fleeces with titers of this order of magnitude; these layers can also be produced from the plastic materials mentioned. Due to the much larger fiber diameters of these conventional plastic fiber nonwovens, however, these are not leakproof for liquid water, and therefore in the present three-layer structure they essentially serve as a mechanical support layer.

The weight per unit area of this conventional plastic water reservoir, which means 22 and 33 layers, is of the order of 20 to 150 g / m 2. The top layer 2 is coated on the outside with bitumen. The bitumen used for this can be conventional oxidation bitumen with or without filler or conventional SBS or APP modified bitumen with or without filler. The bitumen is coated with an extremely small amount, this amount is in the

2 orders of magnitude between 15 and 70 g / m. This does not result in a coating which is impermeable to liquid water, and nevertheless this coating, in combination with the layer 1 of the meltblown nonwoven, interacts in the direction of increasing the watertightness.

Layer 2 can be coated completely with bitumen, but in the exemplary embodiment shown in the drawing, regions 4 with a small bitumen coating and regions 5 with an increased bitumen coating are arranged next to one another. The areas 5 with a higher bitumen coating protrude beyond the areas 4 with a lower bitumen coating and in this way form strips or ribs which improve the accessibility of the formwork and sarking membrane. The amount of bitumen can be in areas 5 of higher coating

2 lie between 200 and 400 g / m, these areas 5, however, form a maximum of 50% of the total area of the formwork and underlay, preferably less.

On the outside, a thin conventional plastic fiber fleece 7 is applied to the layer 2 coated with bitumen 6.

2, the basis weight of which is between 10 and 50 g / m 2 and which in the areas 5 with a higher bitumen coating may be partially or wholly in these Area is embedded. This fleece 7 forms a mechanical protective layer and stabilizes the bitumen application, which differs in some areas, without noticeably reducing the water vapor permeability of the entire formwork and underlay.

Claims

P A T E N T A N S P R Ü C H E

Diffusion-open formwork and underlay with a bitumen-coated non-woven fabric, characterized in that it has at least one first layer (1) of a meltblown non-woven fabric made of fibers with a fiber titer between 0.04 and 0.7 dtex and one surface with this first layer (1) connected second layer (2) of a nonwoven fabric made of fibers with a fiber titer> 0.7 dtex and that this second layer (2) on the outside with bitumen (6) in one

2 amount between 15 and 70 g / m is coated.

Formwork and sarking membrane according to claim 1, characterized in that the weight per unit area of the

2nd layer (1) is between 10 and 75 g / m.

3. formwork and sarking membrane according to claim 1 or

2, characterized in that the basis weight

_{2 of} the second layer (2) is between 20 and 150 g / m.

4. Formwork and sarking membrane according to one of the preceding claims, characterized in that the first layer (1) is also connected on the opposite side to the second layer (2) across the surface with a third layer (3) forming nonwoven fabric whose fibers have a fiber titer> 0.7 dtex.

5. formwork and underlay according to claim 4, da¬ characterized in that the basis weight of the

2 third layer (3) is between 20 and 150 g / m.

Formwork and sarking membrane according to one of the preceding claims, characterized in that the first layer (1) is connected to the second and possibly the third layer (2 or 3) by thermal welding.

7. formwork and underlay according to one of the preceding claims, characterized in that the fiber titer of the fibers of the second and optionally the third layer (2 or 3) is> 2 dtex.

8. Formwork and sarking membrane according to one of the preceding claims, characterized in that the bitumen coating of the second layer (2) has alternately thinner and thicker coated areas (4 or 5 respectively).

Formwork and sarking membrane according to claim 8, characterized in that the alternating areas (4, 5) have the shape of parallel strips.

10. Formwork and sarking membrane according to claim 8 or 9, characterized in that a maximum of 50% of the surface of the second layer (2) are coated thicker.

11. Formwork and sarking membrane according to one of Ansprü¬ che 8 to 10, characterized in that the second

Layer (2) in thicker coated areas (5) with

2

200 to 400 g / m bitumen is coated.

12. Formwork and underlay according to one of Ansprü¬ che 8 to 11, characterized in that the thicker coated areas (5) of the second layer (2) protrude beyond the thinner coated areas (4).

13. Formwork and sarking membrane according to one of the preceding claims, characterized in that the bitumen layer (6) on the outside with a plastic fleece (7) with a basis weight of 10 to

2 50 g / m is covered.

14. Formwork and underlay according to one of the preceding claims, characterized in that the outside coating has at least in the edge region of the formwork and underlay self-adhesive properties and that this self-adhesive edge area is covered by a silicone-coated cover layer.