FR2708303A1 - Improvement to sealing sheets made of bituminous material - Google Patents

Abstract

Sealing sheet (1) produced by means of one or more layers of a bituminous binder (2), including, on one of its faces, called the interface, and intended to be applied against a support (3) such as a concrete slab forming the upper part of a roof or in particular of a flat roof (terrace), a non-stick coating consisting of a non-peelable heat-meltable film (8), in which sealing sheet the film is made from a plastic that is biaxially drawn (stretched) during its manufacture. According to the invention, this sealing sheet is characterised in that the film includes, over all or part of its surface, a plurality of straight slits (9) which are continuous or semi-continuous, parallel and closely spaced.

Description

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  The present invention relates to a sealing sheet produced by means of one or more layers of a bituminous binder, comprising on one or both of its faces, intended to be assembled in leaktight manner by welding to a support or to a sheet. adjacent, a non-stick coating, consisting of a thin non-peelable, hot-melt film, having

  perforations distributed over its surface.

  FR-A-2 556 391 is already known from the name of the Applicant Company, a structure of this type of sealing sheet, in which the film constituting the non-stick layer is provided with perforations, the number and the dimensions are chosen so that the total surface of these perforations is between 8 and 40% of the surface of the film and that the bonding of the sealing sheet, perforated film side on the support to be sealed, is achievable with efficiency, as long by means of an adhesive agent brought at the time of bonding only by fusion with

  torch of the underside carrying the perforated film.

  Preferably and in a known embodiment of this kind, the bituminous binder layer comprises, at the location of the perforations of the non-stick coating film, a projection of a granular material, such as sand, slate powder or the like. , avoiding mutual bonding of the binder layer through these perforations when this layer is rolled up on itself for transport or storage, before being unrolled on

  place to be applied on the support to be covered.

  The advantages of such a solution, using a non-peelable and hot-melt film, provided with perforations in its surface,

  are on the one hand that it allows to wrap the sheet on it-

  even without problems during its unfolding, and on the other hand that it has a faculty of adhesion with its support also

  both by fusion and by bonding with an added adhesive agent.

  Indeed, the bituminous binder, either covered with an adhesive bonding agent obtained in particular by dissolving bitumen in a solvent, or better still heated by the flame of a torch so as to achieve a suitable softening and local melting of the bitumen , by destroying the perforated film and by providing enough heat to allow diffusion within the bitumen mass of the grains of sand or

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  others scattered in the perforations, may be so

  secured to its support or to the adjacent sheet.

  In the known techniques for using such a sealing sheet of bituminous material, provided with a hot-melt and perforated non-stick film, it is preferably made of a thermoplastic material and in particular of a polymer. such as a chloride or a polyvinyl chloride, or of a thermoplastic polyester, or also of an olefinic copolymer, in particular a polypropylene or a high density polyethylene. The thickness of the film can vary between limits between 3 and 100 microns, preferably between 5 and 30 microns and more especially between 7 and 15 microns. The perforations made in the hot-melt film can have various shapes, and in particular have a square, rectangular, circular, oval or polygonal outline, their dimensions possibly being identical or on the contrary different from one perforation to another, advantageously the perforations of the film have the same dimensions and are distributed in the surface thereof regularly in parallel lines, preferably with an arrangement in

  staggered perforations located on two adjacent lines.

  Furthermore, it has already been observed that, if films made of bi-stretched thermoplastic material are used, in particular films of polypropylene or polyethylene terephthalate, the rate of disappearance of the film can be significantly increased,

  between the perforations made in the anti-coating

  adherent. Indeed, when a bi-oriented film is subjected to heat, it shrinks in the direction perpendicular to the direction

from an area of weakness.

  Thus, on a conventional sealing sheet coated with a full film, the zones of weakness are random (holes, punctures, shocks, hollows and bumps ...), which makes the fusion uncertain and forces the operator to heat too strongly certain areas, which is useless and penalizing economically, and on the other hand may have an impact on the

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  resistance of the bituminous binder itself, liable to deteriorate

irremediably.

  In the case of a non-stick film whose weaknesses are predetermined, as in those comprising perforations, the bitumen covered with a spray of sand or the like, must be sufficiently softened so that the grains of sand penetrate and drown in the less for the most part in the molten bituminous binder. In addition, when the melting occurs, the diameter of the filn holes increases but the diameter of any perforation does not necessarily join all of the adjacent holes, which leaves in the film a more or less continuous network with large holes, which can be detrimental to the desired sealing effect, especially if the film goes as far as

edge of the bituminous sheet.

  The present invention relates to a sealing sheet of the aforementioned type, but which includes an improvement providing remarkable advantages as to the sealing of the bonding obtained and its rapidity of setting in place.

work by fusion.

  According to the invention, the sealing sheet considered, in

  which the non-peelable hot-melt film of the anti-

  adherent consists of a bi-stretched plastic material during its manufacture, is characterized in that the film comprises, through all or part of its surface, a plurality of rectilinear slots, continuous or almost continuous, parallel and close together. As a result, after the film has been applied to the layer or layers of bituminous binder of the sealing sheet and after it has cooled, the appearance of the non-stick coating is not modified, the film being unable to shrink. by being immobilized by the binder and the relatively low temperature thereof. On the other hand, when the sealing sheet is heated, in particular by means of the flame of a blowtorch or by any other means providing sufficient heat to produce a softening of the bituminous binder, a shrinkage of the film may occur at the right of each. slots previously formed in its surface. This is particularly particularly interesting

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  for use with hot air or with a hot blade. If these slots are brought together and in particular separated by a smaller distance than that which exists, in a conventional sealing sheet with perforated film, in particular as described in French patent 2,556,391, the fusion will be

  faster and the localized disappearance of the film more effective.

  Where appropriate, the film of bi-stretched plastic material has a high melting point, such that the addition of heat to the bituminous binder does not necessarily cause the film to disappear. In this variant, in fact, it only suffices that the shrinkage temperature is intermediate between the melting point of the bitumen and that of the film material, so that, as soon as the binder softens and melts, the

film can shrink.

  Advantageously, the film of bi-stretched plastic material is produced in the form of a film of a terephthalic polyester or

polypropylene.

  With such a material, the presence of the slots guarantees on each side of each of them an acceptable shrinkage, in any case such that there is no continuous network, or even a large surface plate, of film. not melted, even

even reconstituted after fusion.

  Preferably, the distance between the parallel slots is at most equal to 1 cm and even more effectively, included

between 1 and 5 mm.

  The bituminous binder of the waterproofing sheet can consist of pure or filled bitumen, or else of a mixture of bitumen and of polymer, such as for example mixtures of bitumen and block copolymer of styrene and butadiene. In a particularly advantageous variant, the binder is based on an elastomeric bitumen, in particular in the peripheral or border regions of the sealing sheet, intended to form lateral covering joints with a

similar neighboring leaf.

  In this case, the parallel and close slots of the non-stick film provide great security of the seal obtained, even if the film is not completely fused. Indeed,

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  the binder is exposed in a multitude of parallel lines, these constituting as many sealing barriers, in particular when they extend parallel to the edge of the sheet. In this variant, the self-welding property of binders based on elastomeric bitumen is particularly valued, in particular if the covering edge of the sheet

neighbor underwent the same treatment.

  Another advantage of the invention results from the ease of implementation of the process necessary to produce straight, parallel and close-apart slits, as opposed to that adopted for forming the perforations of a blank film, prior to its application on the or layers of bituminous binder. With the provisions of the invention, the virgin film is applied as it is to the bitumen layer, before being scarified by usual means, for example using a machine provided with a plurality of fine blades driven or not in rotation and against which the filmed face of the product moves, once the binder layer provided with the virgin film to

suitable temperature.

  The invention will be better understood using the complement of

  description which follows, illustrating an example of implementation,

  given for information and not limitation, with reference to the attached drawing in which: - Figure 1 illustrates a conventional waterproofing sheet, comprising a layer of bituminous binder and a perforated non-stick coating film, in the course of installation sure

a support.

  - Figure 2 illustrates on a larger scale the presentation of the sheet of Figure 1 on the support against which it

applies.

  - Figures 3 and 4 are even larger views

  scale, before and after partial melting of the anti-

  adhesive, on the underside of the sealing sheet according to FIGS. 1 and 2, more particularly illustrating the appearance of the

perforated film it contains.

  - Figures 5 and 6 are views similar to Figures 3 and 4, but showing the improved film implemented according to

the present invention.

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  In FIG. 1, the waterproofing sheet considered is designated as a whole under the reference 1. It comprises in particular one or more layers 2 of a bituminous binder, one of the faces of which is intended to be applied against a surface suitable of a support 3, or underside, is provided with a thin coating 4, non-stick, consisting of a film of a plastic material, in particular a thin non-peelable and hot-melt film of the kind a polymer or copolymer of vinyl chloride, or alternatively of a polyester or of an olefin polymer or copolymer, preferably of a polypropylene or of a

high density polyethylene.

  This film 4 has a very small thickness, notably exaggerated in the drawings, in practice of between 3 and 100 microns, preferably between 3 and 30 microns and better still

between 7 and 15 microns.

  The film 4 has a plurality of perforations 5, through which the layer of bituminous binder 2 appears, these perforations possibly having any suitable geometrical profile, here circular and distributed across the surface of the film 4, preferably evenly and in

  staggered as shown in Figure 3.

  Advantageously, the visible part of the layer 2 through the perforations 5 is sprinkled with a granular material, such as sand or slate powder, so as to avoid that, when the sheet 1 is wound on it -same, as shown in Figure 1, the successive turns thereof do not adhere to each other, allowing instead the unhindered unwinding of the roll formed by the sheet on the

support 3.

  Preferably, the sheet 1 comprises, on its face opposite to that comprising the non-stick film 4, a finishing layer 6, also formed by a granular coating, based on sand.

  Or other. It can also look like the other side.

  Figure 2 illustrates on a larger scale the sealing sheet 1 laid flat before its application to the support 3, the latter being obtained after vigorous but localized heating of the sheet beneath it, in particular to cause the softening and melting of the

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  film and bituminous binder of layer 2 in line with the film and the perforations 5, thus embedding the powdery grains in

the molten binder.

  Figure 3 illustrates the underside of the sheet with the covering film 4 and its perforations 5 through which appears the layer 2, itself sprinkled with grains of

  sand or other 7 to the right of these perforations.

  FIG. 4 represents the same underside after heating, therefore before bonding to the support, the perforations 5 now being delimited by irregular contours due to partial or even total melting at certain points of the film 4, the grains of sand 7 being embedded the bituminous binder 2 in the molten state, so as no longer to interfere with the subsequent bonding to the support. Figures 5 and 6 illustrate the non-stick coating 8 according to the invention, produced using a thin bi-stretched plastic film, this film no longer having perforations 5 as in the prior art, but slots 9 continuous or almost continuous, straight, parallel and close together. In particular, the distance between these slots is at most equal to 1 cm, and is

  preferably between 1 and 5 mm.

  In FIG. 6, the slots 9 thus produced, advantageously formed in the plastic film 8, once the latter is applied to the layer of bituminous binder 2, are shown after heating and local melting of this film, providing a significant shrinkage of the material bi-stretched plastic, revealing a very much larger surface of the binder, thereby improving its adhesion on the support against which the sealing sheet is applied

corresponding.

  Of course, it goes without saying that the invention is not limited to the example of implementation more especially described above with reference to the appended drawing; on the contrary, she embraces

all variants.

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Claims (5)

  1 - Sealing sheet (1) produced by means of one or more layers of a bituminous binder (2), comprising on one of its faces, called the underside and intended to be applied to a support (3), such as a concrete slab forming the upper part of a roof or a terrace in particular, a non-stick coating, consisting of a non-peelable, hot-melt film (8), in which the film consists of a bi-stretched plastic material during its manufacture, characterized in that this film comprises, through all or part of its surface, a plurality of rectilinear slots (9), continuous or almost continuous, parallel and close together.   2 - Sealing sheet according to claim 1, characterized in that the slots (9) are separated by a distance at most equal to 1 cm and preferably between 1 and 5 mm.   3 - sealing sheet according to one of claims 1 or   2, characterized in that the film consists of a polyester terephthalic.   4 - Sealing sheet according to one of claims 1 or   2, characterized in that the film consists of polypropylene. Sealing sheet according to any one of   Claims 1 to 4, characterized in that the film comprises   a thickness between 3 and 100 microns, preferably   between 3 and 30 microns, and better still between 7 and 15 microns.   6 - Sealing sheet according to any one of   Claims 1 to 5, characterized in that the bituminous binder is an elastomeric bitumen.