A WATERPROOFING MEMBRANE FOR ROOFING

Abstract: The invention refers to a waterproofing membrane for roofing comprising at least one water and moisture impervious first sub-layer of bitumen or like material and a second sub-layer which is applied over the first sub-layer. The second sub-layer is comprised of granules of plastic and/or elastomeric material being bonded to the first sub-layer, wherein the waterproofing membrane by means of said granule layer has an essentially fully maintenance-free and environmentally-friendly non-dusting surface structure like a conventional slate-crush bitumen surface. The granules are preferably ground fractions having a flaky form. The granule length is at most 4 mm and preferably within an interval of 0.15-2 mm. The granules may be comprised of integrated recovered plastic and/or elastomeric materials, for example recovered from rejected automotive tires.

Description: A WATER-PROOFING MEMBRANE FOR ROOFING The present invention relates to a roofing waterproofing membrane, comprising at least one water-impervious and moisture-impervious first sub-layer of bitumen or like material, and a protective second sub-layer placed on top of the first sub-layer. Waterproofing membranes of the kind defined in the introduction have long been known and used in the art. In everyday language, such membranes are normally referred to as "roofing felt". However, modern waterproofing membranes are not cellulose-based, but most often based on a polyester material. Paper-based roofing materials have been known since the end of the eighteenth century. The first to arrive was so-called "stenpapper"(stone paper), followed in the first half of the nineteenth century by hand-crafted paper sheets coated with charcoal tar. By 1862, continuous lengths of rag felt impregnated with black coal tar were being produced. Products requiring less maintenance impregnated with oil based bitumen were introduced at the beginning of the 20th century, the oil based bitumen being cleaner than coal tar and also able to withstand sunlight more effectively. It has long been known to include a protective layer, primarily a sand layer, probably since the early 1800s. Initially, this so called maintenance-free asphalted roofing felt was provided with a protective layer of talcum powder, which was later replaced in the 1900s with another material, primarily slate crush, which has been found to provide the best covering of all known protective materials and which also protects more effectively against sunlight than sand and talcum powder. The waterproofing membrane of roofing structures is subjected to many different stresses and strains and must also fulfil many different requirements. For instance, the membrane is subjected to the effects of weather and wind, and the UV light of the sun places the asphalt layer, also referred to here as the bitumen layer, under severe strain which gradually results in cracking and crackling of the membrane. The wind exerts lifting forces on the roofing membrane. In addition, the roofing membrane must be able to withstand parallel movements of its supportive surface as said surface expands and contracts in response to changes in moisture and heat. The roofing membrane shall also, of course, fulfil its sealing function with respect to moisture and water and be able to withstand coverings of snow and also the weight of anyone standing on the roof. The membrane shall also be capable of withstanding the extremely strong forces generated by repeated icing of the roof and melting of the ice formations, which both have a detrimental effect on surface layers and surface coatings. Bitumen-based waterproofing membranes must thus be provided with a protective layer against harmful UV light, among other things, so that their weather resistance and other properties that determine the effective lifetime of the membrane will not be impaired excessively. By "bitumen" is meant here and in the following both natural asphalt and oil asphalt, although other similar crude oil distillation products are also included in the term. Earlier, the bitumen layer on "roofing felt" was comprised of oxidized bitumen, which is relatively sensitive to UV light. By oxidized bitumen is understood a product which is obtained by blowing air through basic bitumen having a softening point of about 50°C, such as to obtain an oxidized product in which the softening point is increased to about 100°C and which has an effective temperature span of down to 0°C. Modern roofing membranes are comprised of so-called polymer- modified bitumen, which is produced by adding a stable polymer in a solid and finely- divided form into a basic bitumen. In this way, there is obtained a greater temperature span than that afforded by the oxidized bitumen product, namely a temperature span of from -10°C up to 140°C when adding an APP-type plastic (Atactic polypropylene) and from -25°C to 120°C when adding a thermoplastic elastomer, e.g. an SBS-type elastomer (styrene-butadiene-styrene). In addition, there is obtained improved flexibility and, to some extent, improved weather resistance and aging resistance and therewith a slightly longer lifetime. When the correct polymer is chosen and the admixture properly prepared, the weather resistance may even be so effective as to enable the crushed slate protective layer to be excluded. The roofing membrane is thus essentially improved and is cleaner to handle and splice. Despite these obvious advantages, however, no products of this nature have entered the market to any great extent, at least not in Sweden and other northern countries which experience a cold winter climate, since such membranes have apparently been judged to have other drawbacks in comparison with the protective coated roofing membranes. Despite the manufacture, storage and use of conventional water proofing membranes having slate-crush bitumen surfaces being encumbered with problems, these membrane materials still fully dominate the market. In the manufacture of such roofing materials, it is necessary to handle crushed slate which generates dust in the work place. Slate material is difficult to load and unload in respect of its transportation and is also difficult to apply in a uniform and dense layer in the manufacture of the membrane. It is the protective layer which, in principle, determines the effective lifetime of the bitumen layer Because snow, ice and water will gradually wear away the slate granules from the bitumen layer, there arises the problem of replacing or restoring the protective layer, and also of removing loose slate granules from guttering and drains and from the general surroundings Because the slate layer is relatively heavy, the roofing material will also be heavy to handle and to work with. However, it is still desired to retain the important advantages that are afforded by bitumen-based water proofing membranes. Such advantages are for instance the ease in which such membranes can be joined together, their relatively long effective lifetime, the use of existing expertise and experience and the effective sealing ability of such membranes at reasonable manufacturing, application and maintenance costs. In our earlier SE-A- 9502197-8 a water proofing membrane is described, which fulfils the above mentioned demands. It has a second sub-layer, the protective layer, consisting of a foil or film of a polymer able to being laminated to the first sub-layer In this way the water proofing membrane will present an essentially totally maintenance-free non-dusting surface structure and has a lifetime being independent of the aging properties of the bitumen layer This membrane however demands some accessory equipment for its fabrication in order to provide the lamination of the polymer film onto the bitumen layer, which implies that the production costs are somewhat higher. Seen only from a strictly structure appearance point of view, the surface may be provided different shapes, for example being brick like or slate like, but the surface structure itself, however, differs essentially from the conventional slate crush surface, which may be considered a disadvantage at least by a "conservative" market part, which wants a surface structure being like a slate crushed membrane. The object of the present invention is to provide an environmentally acceptable membrane which fulfils the environmentally demand of today and which utilises the great advantages by using bitumen, but without the disadvantages associated with earlier known protective membranes. The membrane can be considered as an attractive alternative to the membrane described in our earlier SE-A-9502197-8. The invention is to this end characterized by the features set forth in the following claims. The water proofing membrane according to this invention thus has a second sub¬ layer which consists of granules of plastic and/or elastomer materials being bonded to the first sub-layer. The water proofing membrane is by said granule layer provided an essentially totally maintenance-free, environmentally acceptable, non- dusting surface structure looking like a conventional, slate crushed surface. With the term "granule" is according to usual terminology meant a particle mass consisting of relatively small pieces having been produced by crushing larger pieces or, alternatively, by agglomerating finely divided materials. The granules are here advantagely ground fractions of the elastomeric material, preferably in flake form, but also agglomerated granules may in certain cases be actual and suitable. With the term "flake form" is meant granules having a small thickness if compared with their length and width. The length of the granules is at most 4 mm, preferably a length within the interval 0.15-2 mm. Especially attractive as granules are fractions from disintegrated recovered plastic and/or elastomeric materials, for example rejected or discarded automotive tires. Granule materials based on fractions of tires and any similar products are today available in ever growing amounts on the market and these materials are looking for new applications of use. Such materials are more attractive seen from the costs point of view and from the environmentally point of view any new range of use implies a decreasing load on the environment, since the life-time or use-time for such materials will be increased maybe about 25-30 years. Another attractive granule material may be produced from wastage or overflow from the production of EPDM products, for example cloth or fabric, or from rejected such products. The granules shall advantagely be of a plastic or elastomeric material, which shall be weather-proof, aging-proof, frost-proof and further be able to protect from UV radiation The compatibility with the bitumen layer is not particularly critical, but most important is that the granules are affixed to the bitumen layer. The invention provides in comparison to any prior art water proofing membranes having a slate dotted surface a number of advantages: Environmentally advantages: • The material is in its entirety recoverable by combustion, which facilitates the recycling process for these products. • An essential weight decrease is obtained, which also provides the handling certain economical advantages and makes it possible to produce products having enlarged sizes, thicker and/or longer strings, fewer joints and fewer breakdowns or stoppages during the production. • The handling of all forms of slate are totally eliminated. Applicationally advantages: • The roofs will be essentially non-slipping. • A more soft roofing is provided. Compared with earlier suggested polymer material coated membranes there will be lots of additional advantages, for example that the fabrication process will be simplified, since plastic and/or elastomeric granules may be handled using the same equipment as for slates during transport, storing and application.

Claims: CLAIMS 1. A waterproofing membrane for roofing comprising at least one water and moisture impervious first sub-layer of bitumen or like material and a second sub-layer which is applied over the first sub-layer, characterized in that the second sub-layer is comprised of granules of plastic and/or elastomeric material being bonded to the first sub-layer, wherein the waterproofing membrane by means of said granule layer has an essentially fully maintenance-free and environmentally-friendly non-dusting surface structure like a conventional slate-crush bitumen surface 2 A waterproofing membrane for roofing according to claim 1 , characte rized in that the granules are ground fractions 3 A waterproofing membrane for roofing according to claim 2, characte rized in that the granule fractions have a flaky form 4 A waterproofing membrane for roofing according to claims 1-3, c h a r a c terized in that the granule length is at most 4 mm and preferably within an interval of 015-2 mm 5 A waterproofing membrane for roofing according to claims 1-4 charact erized in that the granules are comprised of integrated recovered plastic and/or elastomeric materials 6 A waterproofing membrane for roofing according to claim 5, characte rized in that the granules are elastomeric material recovered from rejected automotive tires 7 A waterproofing membrane for roofing according to claim 5, characte rized in th at the granules are elastomeric material recovered from waste material from the fabπcation of EPDM products or from rejected products of such type

Inventors: HAELLEWALL NICLAS, HAELLEWALL, NICLAS
Applicants: TRELLEBORG BUILDING PRODUCTS A, TRELLEBORG BUILDING PRODUCTS AB
Application year: 1997
Main classification: E04D5
IPC codes: E04D5