EP0012661B2 - Composite bituminous sheet, in particular for watertight elements - Google Patents

Abstract

This invention relates to a composite bituminous sheet, particularly useful for sealing members. Said sheet consists of a main or external zone (1) formed of a cloth which is substantially non-extensible under low stress surrounding at least one central zone (2) to which it is bound, which is formed of an extensible elastic cloth having a tensile elongation at break of at least 100%, the central and external zones being coated with the same bituminous composition having a high elongation at break and a softening point at least equal to 100 DEG C. when determined according to the standard Ring and Ball test.

Description

The present invention relates to a composite bituminous sheet, usable in particular for sealing elements.

In the family of sealants, in the form of manufactured sheets a few millimeters thick and generally packaged in rolls, there are numerous supports, called reinforcements, coated with bituminous mixtures.

These coated reinforcements (for example based on felt cardboard, glass cloth, glass veil, polyester non-woven, etc.) are used alone or combined with one another by superposition within a sealing sheet.

For most of these bitumen-coated reinforcements, the elastic properties are very low and the elongation under low or high stress does not exceed approximately 50%.

These sealing sheets are used on supports made of masonry, insulating materials, etc., having flat surfaces, in general, or very simple geometric shapes.

However, there are singular points, in particular to structural joints, which cannot be made waterproof by such sheets. For example, if the linear part of a flat expansion joint can be treated with these bituminous sheets folded in the form of bellows, on the other hand, angles, crossings and changes of plane cannot be carried out.

Indeed, during dimensional variations of load-bearing elements (in masonry in particular) spaced a few centimeters, the width of the formed joint can increase or decrease, depending on climatic conditions or by mechanical stresses.

In the linear part of the joint, the sealing function is ensured by the variation of the geometric shape of the sheet folded in bellows in the lyre, and this without the need to lengthen the sheet. At the angles and crossings of joints, the general functioning is similar, but the variable geometric shape is very complex.

To resolve these latter cases, the techniques most commonly used to date consist in manufacturing a plaster or a waterproof coating in situ, by coating a square of glass cloth with a bituminous sealant based on solvent, the solvent used to thin the sealant.

The reliability of such a system produced on site depends on its bone implementation and, mainly, on atmospheric conditions. On the other hand, the installation is not rapid and a physicochemical reaction is possible between the solvents of the putty and the bituminous mass of the underlying and surrounding waterproofing, which results, over time, in the destruction of the sealing function of the system.

The object of the invention is to remedy the drawbacks of the previous methods and to provide a device which adapts to all shapes and dimensions of seals and which can be produced quickly and easily, by traditional means, without resorting to no solvent.

Its subject is a composite bituminous sheet usable in particular for sealing elements, composed of a reinforcing cloth coated with a bituminous composition, characterized in that it consists of an external zone formed of a practically cloth non-stretchable under low stress surrounding at least one central zone formed of an elastic and stretchy fabric having an elongation at break in tension at least equal to 100% whatever the direction of the stress, the whole being coated with the same bituminous composition with high elongation at break having a softening point in the standardized Ball and Ring test at least equal to 100 ° C.

Other characteristics and advantages of the invention will appear on reading the description which follows.

The subject of the invention is therefore a bituminous sheet consisting of two zones each comprising a reinforcement of a different type.

The main or external zone is formed of a canvas of mineral or organic fibers practically non-extensible under low stress, and the central zone consists of a stretch canvas under low stress and elastic, the two zones being coated with the same bituminous binder, this binder consisting of a bituminous composition with high elongation at break having a softening point in the standardized ball and ring test at least equal to 100 ° C.

By central area is meant here an area placed in the sheet so as to be completely surrounded by the outer area to which it is fixed. In the same sheet, there can be several central zones separated from each other.

The main or external area is, as we have just indicated, made from a canvas that is practically non-stretchable under low stress; this fabric, the minimum mass of which is preferably at least 50 g / m ² , can for example be made of glass fibers, polyamide or polyester. It will advantageously have a mechanical tensile strength at least equal to 10 daN / cm in width in the longitudinal direction and in the transverse direction.

Its elongation under low stress must be as low as possible, in order to obtain a non-deformable sheet under the conditions of use at the time of processing. Its thermal resistance must enable it to withstand temperatures of around 180 ° C in steady conditions. On the other hand, once coated with the bituminous composition, it will withstand without damage the flame of a blowtorch.

The central zone is formed by an elastic fabric which can be extended in all directions, which can advantageously be obtained by knitting natural fibers (jute, etc.) and / or synthetic fibers such as polyamide or polyester fibers.

As for the canvas of the external zone, its minimum mass will preferably be of the order of 50 g / m ^2.

Its tensile strength is advantageously greater than a few deca-newtons per centimeter (in particular of the order of 4) mainly for manufacturing reasons and to allow implementation without particular and restrictive precautions.

Its elongation at break in tension is very high and must be at least equal to 100%, regardless of the direction of the stress.

Its elasticity must also be high and, in particular, when it is elongated up to at least 50%, it returns practically instantaneously to its initial state when the stress ceases.

It can withstand relatively high thermal stresses, of the order of 180 to 200 ° C, without losing its elasticity.

The fabrics forming the external zone and the central zone or zones are coated with the same bituminous mass having a high elongation at break and a softening point in the ball and ring test, according to French standard NF T 66008, at least equal to 100 ° C.

Its elongation at break will advantageously be greater than or equal to 500%.

The cold flexibility of the bituminous coating mass is important and can go down to - 15 ° C without rupture, by winding in 5 s on a mandrel of 20 mm in diameter (according to the test described in the standard French NF P 84303.

As bituminous coating composition, it is possible to use, for example, bitumen / SBS mixtures (styrene / butadiene elastomer / triblock styrene) and, preferably, mixtures of BPS type.

BPS bitumen is a bituminous composition which was described in the patent application in France No 78.26336 of the holder, filed on September 13, 1978.

• a) 52 à 78% en poids de bitume;
• b) 20 à 40% en poids de polyoléfine, et
• c) 2 à 8% d'un élastomère butadiène/styrène.

This bituminous composition consists of a ternary mixture of

• a) 52 to 78% by weight of bitumen;
• b) 20 to 40% by weight of polyolefin, and
• c) 2 to 8% of a butadiene / styrene elastomer.

The bitumen is for example a direct or oxidized distillation bitumen, having a penetration between 40 and 220; the polyolefin can be a polypropylene, a polybutylene, a propylene / ethylene copolymer or a propylene / ethylene / butylene copolymer, and the elastomer is in particular a styrene / butadiene copolymer having a molecular weight of between 100,000 and 300,000 approximately.

This BPS composition can also contain a filler and / or a pigment and / or a flame retardant.

The table indicates the properties desired for the composite sheet according to the invention and for its various zones.

To manufacture the composite sheet of the invention, the procedure is preferably carried out as follows.

In a non-stretch fabric under low stress, one or more zones are cut which will form the central zones.

Furthermore, in a sheet of an extensible and elastic canvas, pieces of a size at least equal to that of the cuts made in the first sheet are cut.

The non-extensible fabric was previously coated in a conventional manner by means of a coating machine, or another system, with the desired bituminous composition. The pieces of coated stretch fabric, for their part, are centered on the holes made in the coated non-stretch sheet, and the elements are made integral by welding either along the edges or by covering, the bituminous composition serving to ensure the junction between the central zone and the external zone.

Of course, the central area could be attached to the outer area along its edges by other known means, if desired.

To coat the stretch fabric to form the central area, for example, proceed as follows: the reinforcement is imposed on the reinforcement in the order of 50% in all directions and the fibers are coated by spraying the bituminous composition or by dipping therein at a temperature of 180 to 200 ° C. This gives a flat bituminous sheet of regular thickness and, subsequently, during application, there is a certain dimensional shrinkage, by action of the temperature, which is favorable for use.

From the composite sheet thus obtained, it is possible to make and cut sealing pieces of very variable shape.

In the accompanying drawing, given solely by way of example, FIGS. 1 and 5 represent different types of sealing elements obtained from the composite sheet according to the invention, and FIG. 6 shows such a sealing element put in place at a crossing of joints.

Figs. 1 and 2 represent cut pieces of rectangular shape. In fig. 1, the external zone is represented by the reference 1 and the central zone by the reference 2. In FIG. 2, there is also shown a rectangular element comprising an external zone 3 and two central zones 4.

Fig. 3 represents a cross-shaped element, in which the external zone 5 surrounds a central zone 6.

Fig. 4 represents a T-shaped element, in which the external zone 7 surrounds a central zone 8 disposed approximately at the intersection of the branches of the T.

Finally, fig. 5 represents an L-shaped element, with an external zone 9 surrounding a central zone 10 placed approximately at the meeting point of the branches of the L.

Fig. 6 illustrates the application of a sealing element according to the invention of square shape at the crossing of two seals. In this figure, the sealing sheets of the seals are represented by the references 11, 12, 13 and 14, and the sealing element 15 according to the invention is applied to the crossing of the seals, over the ends of the sealing sheets, so that its central zone 16 is arranged at the intersection of the two joints and can, by its extensible nature, be applied tightly to the grooves of the joints.

The edges of the external zone 17 of the sealing element are fixed in a known manner to the ends of the sealing sheets of said seals.

Whatever the shape of the sealing element according to the invention, the laying technique used is practically the same; it consists in performing a flame welding of a torch on the bituminous supports of the joints.

In the case of application to a joint intersection seal, as shown in FIG. 6, there would be, with a conventional non-extensible and non-retractable material, an excess of material which would result in the formation of folds, whereas, with the elements according to the invention, by simple reheating with the flame of a torch, the central area of the room retracts slightly and most of the folds disappear as a result.

It is also possible to use the sealing elements according to the invention for the treatment of an intersection between a horizontal joint and a vertical joint, the depth of the joints as well as their opening being able to be different and variable.

In this case, we center approximately the central area at the angle formed by the intersection of the two planes, then we weld on one side of the joint the part on the horizontal and vertical parts of the support, then we form the bellows in the joint, finally, the part is welded on the other side of the joint.

During this operation, we realize the fundamental importance of the possibility of multidirectional elongation of the central area which allows to deform the part very easily by simple pressure and to marry the complex shape thus created in the 'space.

The following nonlimiting example is given by way of illustration of the invention.

A sheet consisting of a polyamide fabric, weighing 106 g / m ² , is first coated with a bituminous composition of BPS type.

The characteristics of the coated sheet obtained are as follows:

• - armature (toile) 160 g
• - composition BPS 3 200 g
• - silice blanche 640 g

Composition per square meter:

• - frame (canvas) 160 g
• - BPS 3,200 g composition
• - white silica 640 g

• - dans le sens de la longueur: 40 daN/cm et 20%;
• - dans le sens de la largeur: 30 daN/cm et 20%.

Tensile strength and elongation at break (measured according to French standard NFG 07001):

• - lengthwise: 40 daN / cm and 20%;
• - in the width direction: 30 daN / cm and 20%.

Static punching (according to French standard NF P 84352): more than 22 kg on the perlite-based insulating panel.

Cold foldability (according to French standard NF P 84303): on a mandrel with a diameter of 20 mm, winding time 5 s: no cracks down to -15 ° C.

Furthermore, a polyamide knitted fabric is coated using the same BPS bituminous composition as above. The coated sheet obtained has the following characteristics:

• - armature (tricot) 100 g
• - composition BPS 3 500 g Résistance à la rupture en fraction et allongement correspondant dans les sens de la longueur, de la largeur et diagonal: 6 daN/cm et 200%.

Composition per square meter:

• - frame (knitting) 100 g
• - BPS composition 3 500 g Resistance to fracture in fraction and corresponding elongation in the length, width and diagonal directions: 6 daN / cm and 200%.

Static punching: more than 12 kg on the perlite-based insulating panel.

Cold bendability (determined as above): no cracks down to - 15 ° C.

The BPS bituminous composition used has the following composition:

Claims (9)

1. Composite bituminous sheet, particularly useful for sealing members, composed of a reinforcing cloth coated with a bituminous composition, characterized in that it comprises an external zone (1, 3, 5, 7, 9, 17) formed of a cloth substantially non-extensible under low tension surrounding at least one central zone (2,4,6,8,10, 16) formed of an extensible elastic cloth having a tensile elongation at break at least equal to 100% whatever the direction of the stress, the whole being coated with a same bituminous composition having a high elongation at break and a softening point at least equal to 100% when determined according to the standard Ring and Ball Test.

2. Sheet according to Claim 1, characterized in that the central and external zones are welded together along, or by overlapping of, their adjacent edges by means of the bituminous coating composition.

3. Sheet according to one of Claims 1 or 2, characterized in that the central zone is formed of a knitted material of polyamide or polyester yarns.

4. Sheet according to one of the preceding claims, characterized in that the central zone is capable of undergoing a surface shrinkage under the effect of temperature.

5. Sheet according to one of the preceding claims, characterized in that the external zone is formed of a glass fibre, a polyamide fibre or a polyester fibre cloth.

6. Sheet according to one of the preceding claims, characterized in that the cloths forming the central and external zones each have a weight of at least 50 g_/m ².

7. Sheet according to one of the preceding claims, characterized in that the cloth forming the external zone has a tensible mechanical strength at break at least equal to 10 daN/cm of width, both lengthwise and crosswise.

8. Cloth according to one of the preceding claims, characterized in that the bituminous coating composition is a binary bitumen/SBS or a ternary bitumen/polyolefin/butadiene-styrene elastomer composition.

9. Sheet according to one of the preceding claims, characterized in that the bituminous coating composition has an elongation at break of at least 500%.

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