WO2022178873A1

WO2022178873A1 - A roofing membrane having improved aging resistance

Info

Publication number: WO2022178873A1
Application number: PCT/CN2021/078285
Authority: WO
Inventors: Shenghua XU; Qin WEI; Yizhe Wei
Original assignee: Sika Technology Ag
Priority date: 2021-02-26
Filing date: 2021-02-26
Publication date: 2022-09-01
Also published as: CN116917120A

Abstract

The invention is directed to a roofing membrane (1) comprising a polyvinylchloride-based membrane (2) and a protective layer covering at least a portion of an upper major surface of the polyvinylchloride-based membrane (2). The invention is also directed to a method for producing a roofing membrane and to a roof system comprising a roof underlayment (6) and a roofing membrane (1) attached to a surface of the roof underlayment (6) by using mechanical or adhesive bonding means.

Description

A roofing membrane having improved aging resistance

Technical field

The invention relates to the field of waterproofing of above ground building constructions by using roofing membranes. In particular, the invention relates to roofing membranes having an improved resistance against aging.

Background of the invention

In the field of construction polymeric sheets, which are often referred to as membranes, panels, or sheets, are used to protect underground and above ground constructions, such as basements, tunnels, and flat and low-sloped roofs, against penetration water. Waterproofing membranes are applied, for example, to prevent ingress of water through cracks that develop in concrete structures due to building settlement, load deflection, or concrete shrinkage. Roofing membranes used for waterproofing of flat and low-sloped roof structures are typically provided as single-ply or multi-ply membrane systems. In a single-ply system, the roof substrate is covered using a roofing membrane composed of a single polymeric waterproofing layer. In this case, the waterproofing layer typically contains a reinforcement layer to increase the mechanical stability of the roofing membrane. In multi-ply membrane systems, roofing membranes comprising multiple polymeric waterproofing layers having similar or different composition are used. Single-ply membranes have the advantage of lower production costs compared to the multi-ply membranes, but they are also less resistant to mechanical damages caused by punctures of sharp objects.

Commonly used materials for the roofing membranes include plastics, in particular thermoplastics such as plasticized polyvinylchloride (p-PVC) , thermoplastic olefins (TPE-O, TPO) , and elastomers such as ethylene- propylene diene monomer (EPDM) . The roofing membranes are typically delivered to a construction site in form of rolls, transferred to the place of installation, unrolled, and adhered to the substrate to be waterproofed. The substrate on which the roofing membrane is adhered may be comprised of variety of materials. The substrate may, for example, be a concrete, metal, or wood deck, or it may include an insulation board or a cover board and/or an existing membrane.

Roofing membranes are exposed to various stresses during their lifetime including thermal stresses, prolonged exposure to ozone and ultraviolet irradiation, and mechanical stresses. PVC membranes are considered to be especially susceptible to weathering since the gradual migration of plasticizers will stiffen the membrane and accelerate aging of the membrane. Therefore, a guarantee period not more than 10 –20 years is typically given to commercially available roofing membranes based on plasticized polyvinylchloride (p-PVC) . Ketone Ethylene Ester (KEE) membranes can be given a longer guarantee of more than 25 years, because KEE, as a polymer plasticizer, does not need additional plasticizers to increase the flexibility of the membrane. EPDM membranes are inherently more resistant to aging due to their chemically cross-linked structure and have correspondingly a longer warranty period. Even thermoplastic polyolefin (TPO) membranes are claimed to be more resistant against weathering mainly since they do not contain any plasticizers.

Commonly known techniques to extend the life span of a PVC roofing membrane include, for example, using a low volatility plasticizer having a lower migration speed. However, the aging of the membrane is not only influenced by the migration of plasticizers. Fractures in the polymer chains and migration of other volatile additives than plasticizers also promotes aging of the membrane. Some providers increase the thickness of the roofing membrane in order extend the service life. Although adding the material weight will increase the aging resistance to some extent it will also increase the weight per unit area of the membrane, which is a significant disadvantage during the installation of the membrane. Some commercially available membranes are also equipped with a top surface coating to reduce the volatilization and migration of plasticizers, while also providing scaling resistance and easy cleaning. Such coatings are, however, themselves not very resistant against aging and typically the coating will wear away and has to be replaced every couple of years to maintain the protective function. The service life of a roofing membrane can, therefore, be improved by using protective coatings, but the maintenance costs of such roof systems are actually quite high since re-coating of the membrane requires a certain amount of manpower and material resources.

There thus remains a need for a novel type of roofing membrane having improved resistance against aging, and which membrane can consequently be given a longer guarantee period.

Summary of the invention

The object of the present invention is to provide a roofing membrane having improved resistance against aging.

Another object of the present invention is to provide a roofing membrane having improved resistance against exposure to UV-irradiation, migration of plasticizers, and fouling.

The subject of the present invention is a roofing membrane as defined in claim 1.

It was surprisingly found out that a roofing membrane comprising a polyvinylchloride-based membrane, a fluorocarbon-based protective layer covering an upper major surface of the polyvinylchloride-based membrane and a connecting layer arranged between the protective layer and the polyvinylchloride-based membrane, is able to solve or at least mitigate the problems of the State-of-the-Art self-adhering polyvinylchloride-based roofing membranes.

One of the advantages of the roofing membrane of the present invention is that the improved aging resistance can be achieved without significantly increasing the production costs of the membrane.

Another advantage of the roofing membrane of the present invention is that the protective layer has turned out to be much more resilient against environmental impact than the protective coatings of prior art that have been used to extend the service life of already installed roofing membranes.

Other aspects of the present invention are presented in other independent claims. Preferred aspects of the invention are presented in the dependent claims.

Brief description of the Drawings

Fig. 1 shows a cross-section of a roofing membrane (1) comprising a polyvinylchloride-based membrane (2) having upper and lower major surfaces, a protective layer (3) covering the upper major surface of the polyvinylchloride-based membrane (2) , and a connecting layer (4) arranged between the polyvinylchloride-based membrane (2) and the protective layer (3) .

Fig. 2 shows a cross-section of a roofing membrane (1) of Fig. 1 further comprising a layer of fiber material (5) covering the lower major surface of the polyvinylchloride-based membrane (2) .

Fig. 3 shows a cross-section of a roofing membrane (1) of Fig. 1, wherein the polyvinylchloride-based membrane (2) is a multi-ply membrane composed of first and second waterproofing layers.

Fig. 4 shows a cross-section of a roof system comprising a roof underlayment (6) and a roofing membrane (1) of Figure 1 adhered to a surface of the roof underlayment (6) via an adhesive layer (7) .

Detailed description of the invention

The subject of the present invention is a roofing membrane (1) comprising:

i. A polyvinylchloride-based membrane (2) having upper and lower major surfaces,

ii. A protective layer (3) covering at least a portion of the upper major surface of the polyvinylchloride-based membrane (2) , and

iii. A connecting layer (4) arranged between the protective layer (3) and the polyvinylchloride-based membrane (2) ,

characterized in that the protective layer (3) comprises at least one fluorocarbon resin.

Substance names beginning with "poly" designate substances which formally contain, per molecule, two or more of the functional groups occurring in their names. For instance, a polyol refers to a compound having at least two hydroxyl groups. A polyether refers to a compound having at least two ether groups.

The term “polymer” designates a collective of chemically uniform macromolecules produced by a polyreaction (polymerization, polyaddition, polycondensation) where the macromolecules differ with respect to their degree of polymerization, molecular weight and chain length. The term also comprises derivatives of said collective of macromolecules resulting from polyreactions, that is, compounds which are obtained by reactions such as, for example, additions or substitutions, of functional groups in predetermined macromolecules and which may be chemically uniform or chemically non-uniform.

The term “glass transition temperature” (T _g) designates the temperature above which temperature a polymer component becomes soft and pliable, and below which it becomes hard and glassy. The glass transition temperature is preferably determined by dynamical mechanical analysis (DMA) as the peak of the measured loss modulus (G” ) curve using an applied frequency of 1 Hz and a strain level of 0.1 %.

The “amount or content of at least one component X” in a composition, for example “the amount of the at least one fluorocarbon resin” refers to the sum of the individual amounts of all fluorocarbon resins contained in the composition. Furthermore, in case the composition comprises 20 wt. -%of at least one fluorocarbon resin, the sum of the amounts of all fluorocarbon resins contained in the composition equals 20 wt. -%.

The term “room temperature” designates a temperature of 23 ℃.

The roofing membrane of the present invention comprises polyvinylchloride-based membrane, a protective layer, and a connecting layer. The term “layer” refers in the present disclosure to a sheet-like element having upper and lower major surfaces, a width defined between longitudinally extending edges, and a thickness defined between the upper and lower major surfaces. Preferably, a layer has a length and width at least 5 times, more preferably at least 15 times, even more preferably at least 25 times greater than the thickness of the layer.

The polyvinylchloride-based membrane can be a single-ply or a multi-ply membrane. The term “single-ply membrane” designates in the present document membranes comprising one single waterproofing layer whereas the term “multi-ply roofing membrane” designates membranes comprising more than one waterproofing layer. Single-and multi-ply membranes are known to a person skilled in the art and they may be produced by using any conventional means, such as by way of extrusion or co-extrusion, calendaring, or by spread coating. In case the polyvinylchloride-based membrane comprises more thjan one waterproofing layer, the expression “upper major surface of the membrane” refers to the top surface of the uppermost waterproofing layer whereas the expression “lower major surface of the membrane” refers to the bottom surface of the lowermost waterproofing layer.

Preferably, the protective layer covers at least 50 %, more preferably at least 65 %, even more preferably at least 75 %, still more preferably at least 85 wt. -%, of the area of the upper major surface of the polyvinylchloride-based membrane. It may however be preferable that narrow segments, also known as selvedges, on the upper major surface of the polyvinylchloride-based membrane near the longitudinal edges are left free of the protective layer. Such selvedges having a width of 25 –150 mm, preferably 35 –100 mm, may be present in the roofing membrane to enable overlapping and bonding of the overlapped portions of adjacent roofing membranes to each other by means of heat-welding or adhesive bonding.

Fluorocarbon resin-based layers and films have found out as especially suitable for use as the protective layer since they provide excellent resistance against environmental factors including prolonged exposure to UV-irradiation, ozone, and large temperature fluctuations. Furthermore, fluorocarbon layers have been found out to have an excellent barrier property, which can effectively restrain the volatilization of plasticizers and to slow down the aging of polyvinylchloride-based waterproofing layers. Finally, since fluorocarbon materials have a low surface energy, it is difficult for dust to stick to the surface, which means that a fluorocarbon resin-based layer can also be used as an anti-fouling layer.

Preferably, the at least one fluorocarbon resin comprises at least 25 wt. -%, preferably at least 50 wt. -%, more preferably at least 75 wt. -%, even more preferably at least 85 wt. -%, still more preferably at least 95 wt. -%, of the total weight of the protective layer. According to one or more embodiments, the at least one fluorocarbon resins comprises 50 –99 wt. -%, preferably 65 –99 wt. -%, more preferably 75 –99 wt. -%, even more preferably 85 –99 wt. -%, of the total weight of the protective layer.

According to one or more embodiments, the at least one fluorocarbon resin contained in the protective layer is selected from polyvinyl fluoride (PVF) and polyvinylidene fluoride (PVDF) . Layers comprising PVF and PVDF as the at least one fluorocarbon resin have been found out as especially suitable for use as the protective layer.

Suitable polyvinylidene fluorides to be used in the protective layer have a relatively high vinylidene difluoride content, such as at least 65 wt. -%, preferably at least 75 wt. -%, more preferably at least 85 wt. -%, even more preferably at least 95 wt. -%, based on the weight of the polyvinylidene fluoride.

Suitable monomers that may be copolymerized with the vinylidene difluoride monomers preferably contain carbon-carbon double bonds, which may be allylic, styrenic, ethylenic, alpha-methyl styrene groups, (meth) acrylamide groups, cyanate ester groups, vinyl ether groups, or (meth) acrylic moieties. Examples of suitable co-monomers include ethylene, propylene, isobutylene, styrene, vinyl chloride, vinylidene chloride, difluorochloroethylene, chlorotrifluoroethylene tetrafluoroethylene, trifluoropropylene, hexafluoropropylene, vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylonitrile, N-butoxymethyl (meth) acrylamide, isopropenyl acetate. Homopolymers of vinylidene difluoride repeat units of the formula are also suitable. Thermoplastic polyvinylidene fluorides are preferred but chemically crosslinked versions are also suitable.

Suitable polyvinyl fluorides and polyvinylidene fluorides and are commercially available, for example, under the trade name of

(from Arkema) ; under the trade name of

(from Solvay) ; and under the trade name of

(from Shanghai 3F New Material) , such as

FR903.

Suitable polyvinyl fluoride films to be used as the protective layer are commercially available, for example, under the trade name of

PVF film from DuPont. Suitable polyvinylidene fluoride films are commercially available, for example, from Hangzhou Fumo Science and Technology Company (China) .

According to one or more preferred embodiments, the at least one fluorocarbon resin is polyvinyl fluoride.

According to one or more embodiments, protective layer has a thickness in the range of 5 –250 μm, preferably 15 –200 μm, more preferably 25 –150 μm, even more preferably 35 –125 μm, still more preferably 50 –100 μm.

Preferably, the protective layer forms one of the primary exterior surfaces of the roofing membrane. The term “primary exterior surface” refers in the present disclosure to the outermost surfaces of roofing membrane.

The roofing membrane of the present invention further comprises a connecting layer arranged between the polyvinylchloride-based membrane and the protective layer.

Suitable connecting layers for use in the roofing membrane of the present invention include adhesive layers and thermoplastic layers. The thickness of the connecting is not particularly restricted, and it depends mainly on the type of the connecting layer.

Suitable adhesives for use in the connecting layer include, for example, one-component and two-component polyurethane and epoxide adhesives, reactive hot-melt adhesives, and acrylic adhesives.

According to one or more embodiments, the connecting layer is a thermoplastic layer comprising at least one thermoplastic elastomer (TPE) . Thermoplastic elastomers is a group of materials including copolymers and physical or reactor blend of polymers, typically a plastic and a rubber that have both thermoplastic and elastic properties. Commercially available thermoplastic elastomers include, for example, styrene block copolymers (TPS or TPE-s) , thermoplastic polyolefin elastomers (TPO or TPE-o) , thermoplastic vulcanizates (TPV or TPE-v) , thermoplastic polyurethanes (TPU) , thermoplastic copolyesters (TPC or TPE-E) , and thermoplastic polyamides (TPA or TPE-A) .

Preferably, the at least one thermoplastic elastomer comprises at least 25 wt. -%, preferably at least 50 wt. -%, more preferably at least 75 wt. -%, even more preferably at least 85 wt. -%, still more preferably at least 95 wt. -%, of the total weight of the connecting layer. According to one or more embodiments, the at least one thermoplastic elastomer comprises 50 –99 wt. -%, preferably 65 –99 wt. -%, more preferably 75 –99 wt. -%, even more preferably 85 –99 wt. -%, of the total weight of the connecting layer.

According to one or more preferred embodiments, the at least one thermoplastic elastomer is a thermoplastic polyurethane (TPU) .

Thermoplastic polyurethanes are block copolymers consisting of alternating sequences of hard and soft segments or domains formed by the reaction of (1) diisocyanates with short-chain diols (so-called chain extenders) and (2) diisocyanates with long-chain diols. Suitable thermoplastic polyurethanes for use in the connecting layer include aliphatic and aromatic polyester-based and polyether-based TPUs. These are commercially available, for example, under the trade name of

(from BASF) ,

and

(from Lubrizol) ,

(from Covestro) , and

and

(from Huntsman) .

Suitable TPU-based films for use as the connecting layer are commercially available, for example, from Plastic Film Corporation (USA) , Shenzhou Jinlong Fluorine Plastic Products Factory (China) , and from Dongguan Feng Tian Plastic Products Co., Ltd (China) .

Preferably, the connecting layer has a thickness of not more than 300 μm, more preferably not more than 250 μm, even more preferably not more than 200 μm. According to one or more embodiments, the connecting layer has a thickness in the range of 5 –150 μm, preferably 15 –150 μm, more preferably 35 –125 μm, even more preferably 50 –100 μm. Connecting layers having a thickness within the above cited ranges have been found out to enable providing sufficient bonding strength between the protective layer and the polyvinylchloride-based membrane without having significant impact on the production costs of the roofing membrane.

Preferably, at least a portion of the upper major surface of the polyvinylchloride-based membrane is directly connected to a surface of the connecting layer and/or at least a portion of a lower major surface of the protective layer is directly connected to a surface of the connecting layer. The expression “directly connected” is understood to mean in the context of the present invention that no further layer or substance is present between the layers, and that the opposing surfaces of the layers are directly bonded to each other or adhere to each other. At the transition area between the two layers, the materials of the layers can also be present mixed with each other.

In case of the thermoplastic connecting layer, the connecting layer can be bonded to the polyvinylchloride-based membrane and to the protective layer using any suitable means, such as by using heat (hot) -pressing, thermo-laminating, or adhesive lamination techniques. The term “thermo-laminating” refers in the present disclosure to a process in which the respective layers are bonded to each other by the application of heat and pressure and without using an adhesive, such that the layers remain adhered to each other when the pressure is removed. Furthermore, the term “adhesive lamination” refers to a process in which the respective layers are bonded to each by using an adhesive composition.

According to one or more embodiments, the connecting layer has been thermally laminated to at least a portion of the upper major surface of the polyvinylchloride-based membrane in a manner that gives direct bonding between the connecting layer and the polyvinylchloride-based membrane and/or the protective layer has been thermally laminated to at least a portion of an upper major surface of the connecting layer in a manner that gives direct bonding between the protective layer and the connecting layer.

The type of the polyvinylchloride-based membrane is not particularly restricted in the present invention. The membrane can be a singly-ply membrane comprising one single waterproofing layer of a multi-ply membrane comprising several waterproofing layers. The preferred thickness also depends on the number waterproofing layers. According to one or more embodiments, the polyvinylchloride-based membrane has a thickness determined by using the measurement method as defined in EN 1849-2: 2019 standard in the range of 0.5 –5.0 mm, preferably 0.75 –3.5 mm, more preferably 1.0 –3.0 mm, even more preferably 1.0 –2.5 mm.

According to one or more embodiments, the polyvinylchloride-based membrane comprises at least one waterproofing layer comprising:

a) 25 –65 wt. -%, preferably 35 –55 wt. -%, of a polyvinylchloride resin,

b) 10 –50 wt. -%, preferably 15 –45 wt. -%, of at least one plasticizer, and

c) 0 –30 wt. -%, preferably 1 –30 wt. -%, of at least one inert mineral filler, all proportions being based on the total weight of the waterproofing layer.

Preferably, polyvinylchloride resin has a K-value determined by using the method as described in ISO 1628-2-1998 standard in the range of 50 –85, more preferably 65 –75. The K-value is a measure of the polymerization grade of the polyvinylchloride resin and it is determined from the viscosity values of the polyvinylchloride homopolymer as virgin resin, dissolved in cyclohexanone at 30 ℃.

Preferably, the composition of the waterproofing layer has a glass transition temperature (T _g) , determined by dynamical mechanical analysis (DMA) using an applied frequency of 1 Hz and a strain level of 0.1 %, of below –20 ℃, more preferably below –25 ℃.

The type of the at least one plasticizer is not particularly restricted in the present invention. Suitable plasticizers for the PVC-resin include but are not restricted to, for example, linear or branched phthalates such as di-isononyl phthalate (DINP) , di-nonyl phthalate (L9P) , diallyl phthalate (DAP) , di-2-ethylhexyl-phthalate (DEHP) , dioctyl phthalate (DOP) , diisodecyl phthalate (DIDP) , and mixed linear phthalates (911 P) . Other suitable plasticizers include phthalate-free plasticizers, such as trimellitate plasticizers, adipic polyesters, and biochemical plasticizers. Examples of biochemical plasticizers include epoxidized vegetable oils, for example, epoxidized soybean oil and epoxidized linseed oil and acetylated waxes and oils derived from plants, for example, acetylated castor wax and acetylated castor oil.

Particularly suitable phthalate-free plasticizers to be used in the waterproofing layer include alkyl esters of benzoic acid, dialkyl esters of aliphatic dicarboxylic acids, polyesters of aliphatic dicarboxylic acids or of aliphatic di-, tri-and tetrols, the end groups of which are unesterified or have been esterified with monofunctional reagents, trialkyl esters of citric acid, acetylated trialkyl esters of citric acid, glycerol esters, benzoic diesters of mono-, di-, tri-, or polyalkylene glycols, trimethylolpropane esters, dialkyl esters of cyclohexanedicarboxylic acids, dialkyl esters of terephthalic acid, trialkyl esters of trimellitic acid, triaryl esters of phosphoric acid, diaryl alkyl esters of phosphoric acid, trialkyl esters of phosphoric acid, and aryl esters of alkanesulphonic acids.

According to one or more embodiments, the at least one plasticizer is selected from the group consisting of phthalates, trimellitate plasticizers, adipic polyesters, and biochemical plasticizers.

The term “inert mineral filler” designates in the present document mineral fillers, which, unlike mineral binders are not reactive with water, i.e. do not undergo a hydration reaction in the presence of water. Preferably the at least one inert mineral filler is selected from the group consisting of sand, granite, calcium carbonate, clay, expanded clay, diatomaceous earth, pumice, mica, kaolin, talc, dolomite, xonotlite, perlite, vermiculite, Wollastonite, barite, magnesium carbonate, calcium hydroxide, calcium aluminates, silica, fumed silica, fused silica, aerogels, glass beads, hollow glass spheres, ceramic spheres, bauxite, comminuted concrete, and zeolites.

The term “sand” refers in the present document to mineral clastic sediments (clastic rocks) which are loose conglomerates (loose sediments) of round or angular small grains, which were detached from the original grain structure during the mechanical and chemical degradation and transported to their deposition point, said sediments having an SiO ₂ content of greater than 50 wt. -%, in particular greater than 75 wt. -%, particularly preferably greater than 85 wt. -%. The term “calcium carbonate” as inert mineral filler refers in the present document to calcitic fillers produced from chalk, limestone or marble by grinding and/or precipitation.

According to one or more embodiments, the at least one mineral filler is present in the waterproofing layer in an amount of 5 –30 wt. -%, preferably 10 –30 wt. -%, more preferably, 15 –30 wt. -%, based on the total weight of the waterproofing layer.

According to one or more embodiments, the waterproofing layer further comprises:

d) 0 –15 wt. -%, preferably 0.5 –10 wt. -%, more preferably 0.5 –7.5 wt. -%, based on the total weight of the waterproofing layer, of at least one flame retardant.

The at least one flame retardant is preferably selected from the group consisting of magnesium hydroxide, aluminum trihydroxide, antimony trioxide, ammonium polyphosphate, and melamine-, melamine resin-, melamine derivative-, melamine-formaldehyde-, silane-, siloxane-, and polystyrene-coated ammonium polyphosphates.

Other suitable flame retardants for use as the at least one flame retardant include, for example, 1, 3, 5-triazine compounds, such as melamine, melam, melem, melon, ammeline, ammelide, 2-ureidomelamine, acetoguanamine, benzoguanamine, diaminophenyltriazine, melamine salts and adducts, melamine cyanurate, melamine borate, melamine orthophosphate, melamine pyrophosphate, dimelamine pyrophosphate and melamine polyphosphate, oligomeric and

polymeric

1, 3, 5-triazine compounds and polyphosphates of 1, 3, 5-triazine compounds, guanine, piperazine phosphate, piperazine polyphosphate, ethylene diamine phosphate, pentaerythritol, borophosphate, 1, 3, 5-trihydroxyethylisocyanaurate, 1, 3, 5-triglycidylisocyanaurate, triallylisocyanurate and derivatives of the aforementioned compounds.

Suitable flame retardants are commercially available, for example, under the trade names of

and

(both from Albemarle) and under the trade names of

(from Clariant) ,

(from Phos-Check) and FR

(from Budenheim) .

The waterproofing layer can comprise further auxiliary components, for example, UV-and heat stabilizers, antioxidants, dyes, pigments such as titanium dioxide and carbon black, matting agents, antistatic agents, impact modifiers, biocides, and processing aids such as lubricants, slip agents, antiblock agents, and denest aids. The total amount of these auxiliary components is preferably not more than 45 wt. -%, more preferably not more than 35 wt. -%, even more preferably not more than 25 wt. -%, based on the total weight of the waterproofing layer.

According to one or more further embodiments, the polyvinylchloride-based membrane is a multi-ply membrane comprising a first waterproofing layer and a second waterproofing layer. Preferred embodiments of the waterproofing layer have already been discussed above. Preferably, the first and second waterproofing layers are directly or indirectly connected to each other over at least a portion of their opposing major surfaces.

Suitable polyvinylchloride-based membranes are commercially available, for example, from Sika Corporation under the trade names of

and

from Versico Roofing Systems under the trade name of

PVC; from GAF under the trade name of

PVC; from Carlisle SynTec Systems under the trade name of

PVC; and from Johns Manville under the trade name of

PVC.

According to one or more embodiments, the roofing membrane further comprises a layer of fiber material, which is fully embedded into the polyvinylchloride-based membrane or covering at least a portion of the lower major surface of the polyvinylchloride-based membrane. By the expression “fully embedded” is meant that the layer of fiber material layer is fully covered by the matrix of the polyvinylchloride-based membrane, particularly fully covered by the matrix of the waterproofing layer.

The layer of fiber material may be used to ensure the mechanical stability when the roofing membrane is exposed to varying environmental conditions, in particular to large temperature fluctuations. The layer of fiber material may also be used as a barrier layer to prevent the migration of plasticizers from the roofing membrane to an adhesive layer or vice versa when the adhesive layer is used to bond the roofing membrane to a roof substrate, such as a roof underlayment.

The term “fiber material” designates in the present document materials composed of fibers comprising or consisting of, for example, organic, inorganic or synthetic organic materials. Examples of organic fibers include, for example, cellulose fibers, cotton fibers, and protein fibers. Particularly suitable synthetic organic materials include, for example, polyester, homopolymers and copolymers of ethylene and/or propylene, viscose, nylon, and polyamides. Fiber materials composed of inorganic fibers are also suitable, in particular, those composed of metal fibers or mineral fibers, such as glass fibers, aramid fibers, wollastonite fibers, and carbon fibers. Inorganic fibers, which have been surface treated, for example, with silanes, may also be suitable. The fiber material can comprise short fibers, long fibers, spun fibers (yarns) , or filaments. The fibers can be aligned or drawn fibers. It may also be advantageous that the fiber material is composed of different types of fibers, both in terms of geometry and composition.

Preferably, the layer of fiber material is selected from the group consisting of non-woven fabrics, woven fabrics, and laid scrims.

The term “non-woven fabric” designates in the present document materials composed of fibers, which are bonded together by using chemical, mechanical, or thermal bonding means, and which are neither woven nor knitted. Non-woven fabrics can be produced, for example, by using a carding or needle punching process, in which the fibers are mechanically entangled to obtain the nonwoven fabric. In chemical bonding, chemical binders such as adhesive materials are used to hold the fibers together in a non-woven fabric.

The term “laid scrim” refers in the present disclosure web-like non-woven products composed of at least two sets of parallel yarns (also designated as weft and warp yarns) , which lay on top of each other and are chemically bonded to each other. The yarns of a non-woven scrim are typically arranged with an angle of 60 –120°, such as 90 ± 5°, towards each other thereby forming interstices, wherein the interstices occupy more than 60%of the entire surface area of the laid scrim. Typical materials for laid scrims include metal fibers, inorganic fibers, in particular glass fibers, and synthetic organic fibers, in particular polyester, polypropylene, polyethylene, and polyethylene terephthalate (PET) .

According to one or more embodiments, the layer of fiber material is a non-woven fabric, preferably having a mass per unit area of not more than 350 g/m ², preferably not more than 300 g/m ². According one or more embodiments, the layer of fiber material is a non-woven fabric having a mass per unit area of 15 –300 g/m ², preferably 20 –250 g/m ², more preferably 25 –200 g/m ², even more preferably 30 –150 g/m ².

Preferably, the non-woven fabric comprises synthetic organic and/or inorganic fibers. Particularly suitable synthetic organic fibers for the non-woven fabric include, for example, polyester fibers, polypropylene fibers, polyethylene fibers, nylon fibers, and polyamide fibers. Particularly suitable inorganic fibers for the non-woven fabric include, for example, glass fibers, aramid fibers, wollastonite fibers, and carbon fibers.

According to one or more embodiments, the non-woven fabric of the layer of fiber material has as the main fiber component synthetic organic fibers, preferably selected from the group consisting of polyester fibers, polypropylene fibers, polyethylene fibers, nylon fibers, and polyamide fibers. According to one or more further embodiments, the non-woven fabric of the layer of fiber material has as the main fiber component inorganic fibers, preferably selected from the group consisting of glass fibers, aramid fibers, wollastonite fibers, and carbon fibers, more preferably glass fibers.

It may furthermore be preferred that the roofing membrane shows an impact resistance measured according to EN 12691: 2005 (method A) standard in the range of 200 -1500 mm and/or a longitudinal and a transversal tensile strength measured at a temperature of 23 ℃ according to DIN ISO 527-3 standard of at least 5 MPa and/or a longitudinal and transversal elongation at break measured at a temperature of 23 ℃ according to DIN ISO 527-3 standard of at least 300 %and/or a water resistance measured according to EN 1928 B standard of 0.6 bar for 24 hours and/or a maximum tear strength measured according to EN 12310-2 standard of at least 100 N.

According to one or more embodiments, the roofing membrane further comprises a pressure sensitive adhesive layer arranged on the bottom side of the membrane opposite to the side of the protective layer.

The term “pressure sensitive adhesive” refers in the present disclosure to viscoelastic materials, which adhere immediately to almost any kind of substrates by application of light pressure and which are permanently tacky. The tackiness of an adhesive layer can be measured, for example, as a loop tack. Preferably, the pressure sensitive adhesive layer has a loop tack adhesion to a glass plate measured at a temperature of 23 ℃ of at least 2.5 N/25 mm, preferably at least 5 N/25 mm, more preferably at least 10 N/25 mm. The loop tack adhesion can be measured using a "FINAT test method no. 9 (FTM 9) as defined in FINAT Technical Handbook, 9th edition, published in 2014.

Preferably, the pressure sensitive adhesive layer covers at least 50 %, more preferably at least 75 %, even more preferably at least 85 %, still more preferably at least 95 wt. -%of the area of the lower major surface of the polyvinylchloride-based membrane. According to one or more embodiments, the pressure sensitive adhesive layer covers essentially the whole area of the lower major surface of the polyvinylchloride-based membrane, such as at least 97.5 %, preferably at least 99 %of the area of the lower major surface of the polyvinylchloride-based membrane.

The pressure sensitive adhesive layer can be present on the lower major surface of the polyvinylchloride-based membrane in form of a continuous or a discontinuous adhesive layer. The term “continuous adhesive layer” refers in the present disclosure to layers consisting of one single area coated with an adhesive composition whereas the term “discontinuous adhesive layer” refers to layers consisting of two or more areas coated with an adhesive composition, which areas are not connected to each other to form a continuous layer. According to one or more embodiments, the pressure sensitive adhesive layer is a continuous adhesive layer.

Suitable pressure sensitive adhesives include, for example, water-based, solvent-based, hot-melt, and crosslinked pressure sensitive adhesives, such as UV-cured pressure sensitive adhesives. The term “hot-melt pressure sensitive adhesive (HM-PSA) ” refers in the present disclosure to solvent-free pressure sensitive adhesives, which are applied as a melt.

Suitable pressure sensitive adhesives include adhesives based on acrylic polymers, styrene block copolymers, amorphous polyolefins (APO) , amorphous poly-alpha-olefins (APAO) , vinyl ether polymers, bitumen, and elastomers such as, for example, styrene-butadiene rubber (SBR) , ethylene propylene diene monomer (EPDM) rubber, butyl rubber, polyisoprene, polybutadiene, natural rubber, polychloroprene rubber, ethylene-propylene rubber (EPR) , nitrile rubber, acrylic rubber, ethylene vinyl acetate rubber, and silicone rubber. In addition to the above-mentioned polymers, suitable pressure sensitive adhesives typically comprise one or more additional components including, for example, tackifying resins, waxes, and additives, for example, UV-light absorption agents, UV-and heat stabilizers, optical brighteners, pigments, dyes, and desiccants.

According to one or more embodiments, pressure sensitive adhesive layer is composed of a plasticizer-resistant pressure sensitive adhesive. The term "plasticizer-resistant adhesive" designates in the present disclosure an adhesive that has improved resistance against softening caused by the migration of plasticizers into the adhesive from the substrate (s) on which the adhesive has been applied.

According to one or more preferred embodiments, the pressure sensitive adhesive layer is composed of an acrylic pressure sensitive adhesive. The term “acrylic pressure sensitive adhesive” designates in the present disclosure pressure sensitive adhesive compositions containing one or more acrylic polymers as the main polymer component.

Suitable acrylic pressure sensitive adhesives include, for example, water-based acrylic pressure sensitive adhesives, solvent-based acrylic pressure sensitive adhesives, acrylic hot-melt pressure sensitive adhesives (HM-PSA) , and UV-cured acrylic pressure sensitive adhesives.

Preferred thickness of the pressure sensitive adhesive layer depends on the detailed composition of the adhesive. According to one or more embodiments, the pressure sensitive adhesive layer has a thickness of 25 –500 μm, preferably 50 –350 μm, more preferably 75 –300 μm, even more preferably 100 –250, in particular 100 –200 μm and/or a coating weight of at least 75 g/m ², preferably least 100 g/m ², more preferably at least 125 g/m ², such as 100 –1000 g/m ², preferably 125 –750 g/m ², more preferably 150 –500 g/m ², even more preferably 150 –350 g/m ².

According to one or more embodiments, the roofing membrane further comprises a release liner covering at least portion of the outer major surface of the pressure sensitive adhesive layer facing away from the upper major surface of the polyvinylchloride-based membrane. Preferably, the pressure sensitive adhesive layer and the release liner are directly connected to each other over at least portion of their opposing major surfaces. The release liner may be used to prevent premature unwanted adhesion and to protect the pressure sensitive adhesive layer from moisture, fouling, and other environmental factors. In case the roofing membrane is provided in form of rolls, the release liner enables ease of unwind without sticking of the pressure sensitive adhesive to the back side of the roofing membrane. The release liner may be sliced into multiple sections to allow portioned detachment of the liner from the adhesive layer.

Suitable materials for the release liner include Kraft paper, polyethylene coated paper, silicone coated paper as well as polymeric films, for example, polyethylene, polypropylene, and polyester films coated with polymeric release agents selected from silicone, silicone urea, urethanes, waxes, and long chain alkyl acrylate release agents.

The roofing membrane of the present invention is typically provided in a form of a prefabricated membrane article, which is delivered to the construction site and unwound from rolls to provide sheets having a width of 1 –5 m and length of several times the width. However, the roofing membrane can also be used in the form of strips having a width of typically 1 –25 cm, for example so as to seal joints between two adjacent membranes. Moreover, the roofing membrane can also be provided in the form of planar bodies, which are used for repairing damaged locations in existing adhered waterproofing or roofing systems.

The preferences given above for the polyvinylchloride-based membrane, the protective layer, and to the connecting layer apply equally to all aspects of the present invention unless otherwise stated.

Another subject of the present invention is a method for producing a roofing membrane according to the present invention, the method comprising steps of:

I) Providing a polyvinylchloride-based membrane (2) having upper and lower major surfaces,

II) Laminating a connecting layer (4) to the upper major surface of the polyvinylchloride-based membrane (2) , and

III) Laminating a protective layer to the connecting layer (4) such that the connecting layer (4) forms an interlayer between the polyvinylchloride-based membrane (2) and the protective layer (3) .

The lamination of the individual layers to each other can be conducting using any conventional techniques known to a person skilled in the art, such as heat (hot) -pressing, thermo-laminating, and adhesive lamination. The choice of the suitable lamination technique depend on the embodiments of the roofing membrane.

According to one or more embodiments, the connecting layer is a thermoplastic layer containing at least one thermoplastic elastomer and step II) of the method comprises thermally laminating the connecting layer to the upper major surface of the polyvinylchloride-based membrane and step III) comprises thermally laminating the protective layer to an upper major surface of the connecting layer.

The preferred embodiments of the polyvinylchloride-based membrane, the protective layer, and the connecting layer have already been discussed above.

Another subject of the present invention is a roof system comprising a roof underlayment (6) and a roofing membrane (1) according to the present invention adhered to a surface of the roof underlayment (6) by using mechanical or adhesive bonding means.

According to one or more embodiments, the roof underlayment comprises a cover board and/or an insulation board.

Preferably, the insulation board comprises at least one foam panel having a closed cell structure. Suitable foam panels having a closed cell structure include molded expanded polystyrene (EPS) foam panels, extruded expanded polystyrene (XPS) foam panels, polyurethane foam panels (PUR) , and polyisocyanurate (PIR) foam panels.

The thickness of the insulation board is not particularly restricted. It may be preferable that the insulation board has a thickness determined by using the measurement method as defined in DIN EN 1849-2 standard of 5 –500 mm, preferably 10 –350 mm, even more preferably 25 –150 mm.

According to one or more embodiments, the insulation board comprises at least one foam panel having a closed cell structure selected from the group consisting of molded expanded polystyrene (EPS) foam panel, extruded expanded polystyrene (XPS) foam panel, polyurethane foam panel (PUR) , and polyisocyanurate (PIR) foam panel, preferably having a density in the range of 10 –150 g/l, more preferably 15 –100 g/l, even more preferably 25 –75 g/l.

The insulation board can be secured to a roof substrate, such as a roof deck, by using any suitable fastening means, such as by using adhesive bonding or mechanical fastening means.

According to one or more embodiments, the roof underlayment comprises a cover board.

Suitable cover boards include, for example, gypsum boards, fiber-reinforce gypsum boards, wood fiber boards, cementitious boards, high-density (compressed) polyisocyanurate boards, perlite boards, asphaltic boards, mineral fiber boards, and plywood or oriented strand boards. The cover board may be used in addition of instead of the insulation board.

According to one or more embodiments, the roof underlayment comprises the insulation board and the cover board, wherein the cover board is positioned between the roofing membrane and the insulation board. The cover board can be secured to the insulation board by using any suitable fastening means, such as by using adhesive bonding or mechanical fastening means.

According to or more embodiments, the roof system further comprises a vapor control layer arranged on the bottom side of the roof underlayment opposite to the side of the roofing membrane.

The vapor control layer is liquid impermeable but at least partially permeable to moisture vapor. According to one or more embodiments, the vapor control layer has a water vapor diffusion equivalent air layer thickness value (Sd-value) measured according to the method as defined in ISO 1931 standard of not more than 100 m, preferably not more than 50 m.

According to one or more further embodiments, the vapor control layer has a moisture variable diffusion resistance. In these embodiments, the vapor control layer has a lower water vapor diffusion resistance at higher relative humidity of the surroundings and higher water vapor diffusion resistance at lower relative humidity of the surroundings. For example, the Sd-value of the vapor control layer can be in the range of 0.5 –20 m, preferably 1 –10 m at relative humidity of 80 %, and in the range of 25 –100 m, preferably 35 –65 m at relative humidity of 20 %.

The composition of the vapor control layer is not particularly restricted. Preferably, the vapor control layer comprises at least polymer selected from the group consisting of polyethylene (PE) , polypropylene (PP) , ethylene –vinyl acetate copolymers (EVA) , ethylene –α-olefin co-polymers, ethylene –propylene co-polymers, polyvinylchloride (PVC) , ethylene acrylic acid co-polymers, polyurethane, polyesters, co-polyesters, polyether-esters, polystyrene (PS) , polyethylene terephthalate (PET) , polyamides (PA) , co-polyamides, and ionomers. The term “ionomer” refers to a polymer that comprises ionic groups that are carboxylate salts, for example, ammonium carboxylates, alkali metal carboxylates, alkaline earth carboxylates, transition metal carboxylates and/or combinations of such carboxylates. Such polymers are generally produced by partially or fully neutralizing the carboxylic acid groups of precursor or parent polymers that are acid copolymers, for example, by reaction with a base.

Preferably, the vapor control layer has a thickness of 5 –500 μm, more preferably 25 –350 μm, even more preferably 50 –250 μm and/or a mass per unit are of 25 –500 g/m ², more preferably 50 –350 g/m ², even more preferably 75 –250 g/m ².

According to one or more embodiments, the roofing membrane (1) is adhered to a surface of the roof underlayment (6) via an adhesive layer (7) .

According to one or more embodiments at least 50 %, preferably at least 75 %, most preferably at least 85 %of the area of the lower major surface of the polyvinylchloride-based membrane is adhered to the surface of the roof underlayment via the adhesive layer. According to one or more embodiments, the entire area of the lower major surface of the polyvinylchloride-based membrane is adhered to the surface of the roof underlayment via the adhesive layer.

Examples

Preparation of test specimen

Exemplary membranes comprising a PVC-based membrane, a PVF-based protective layer, and a TPU-based connecting layer between the membrane and the protective layer were prepared by laminating the layers to each other using a hot roll press.

The PVC-based membrane was Sarnafil G410-15 roofing membrane (available from Sika AG) having a nominal thickness 1.5 mm, the TPU-based connecting layer had a thickness of 100 μm (available from Shenzhou Jinlong Fluorine Plastic Products Factory) , and the PVF-based protective layer had a thickness of 25 μm (available from Guan Ou Company) .

A Sarnafil G410-15 roofing membrane without the protective and connecting layers was used as a reference membrane.

The roofing membranes were tested for tensile strength, water vapor permeability, self-cleaning and stain resistance, and for plasticizer migration properties. The results from these measurements are presented in Table 1.

Tensile strength

The tensile strength was measured for samples cut from the test specimen in machine direction. The measurements were conducted according to EN 12311-2: 2013 standard at a temperature of 23 ℃.

Water Vapor Permeability

Water vapor permeability (transmission) properties were tested by measuring the Sd value by using the method as defined in 1931: 2000 standard.

Self-cleaning and stain resistance

Self-cleaning and stain resistance properties were measured by using the method as defined in GB/T 9780-2013 standard using a standard dust coating and water as a washing medium.

Plasticizer migration

Isolation properties of the protective film were tested by measuring the amount of plasticizer migration (weight loss) from the PVC roofing membrane into a polystyrene board during a test period of 12 weeks.

Table 1

Claims

A roofing membrane (1) comprising:

i. A polyvinylchloride-based membrane (2) having upper and lower major surfaces,

ii. A protective layer (3) covering at least a portion of the upper major surface of the polyvinylchloride-based membrane (2) , and

iii. A connecting layer (4) arranged between the protective layer (3) and the polyvinylchloride-based membrane (2) ,

characterized in that the protective layer (3) comprises at least one fluorocarbon resin.
The roofing membrane according to claim 1, characterized in that the at least one fluorocarbon resin comprises at least 50 wt. -%, preferably at least 75 wt. -%, of the total weight of the protective layer (3) .
The roofing membrane according to claim 1 or 2, characterized in that the at least one fluorocarbon resin is selected from polyvinyl fluoride and polyvinylidene fluoride.
The roofing membrane according to any one of previous claims, characterized in that protective layer (3) has a thickness in the range of 25 –150 μm, preferably 50 –100 μm.
The roofing membrane according to any one of previous claims, characterized in that the protective layer (3) forms one of the primary exterior surfaces of the roofing membrane.
The roofing membrane according to any one of previous claims, characterized in that the connecting layer (4) is an adhesive layer or a thermoplastic layer comprising at least one thermoplastic elastomer (TPE) , preferably a thermoplastic polyurethane (TPU) .
The roofing membrane according to claim 6, wherein the at least one thermoplastic elastomer comprises at least 50 wt. -%, preferably at least 75 wt. -%, of the total weight of the connecting layer (4) .
The roofing membrane according to any one of previous claims, characterized in that the connecting layer (4) has a thickness 5 –150 μm, preferably 35 –125 μm.
The roofing membrane according to any one of previous claims, characterized in that at least a portion of the upper major surface of the polyvinylchloride-based membrane (2) is directly connected to a surface of the connecting layer (4) and/or at least a portion of a lower major surface of the protective layer (3) is directly connected to a surface of the connecting layer (4) .
The roofing membrane according to any one of previous claims, characterized in that the polyvinylchloride-based membrane (2) has a thickness determined by using the measurement method as defined in EN 1849-2: 2019 standard of 0.5 –5.0 mm, preferably 0.75 –3.5 mm.
The roofing membrane according to any one of previous claims, characterized in that the polyvinylchloride-based membrane (2) comprises at least one waterproofing layer comprising:

a) 25 –65 wt. -%of a polyvinylchloride resin,

b) 10 –50 wt. -%of at least one plasticizer, and

c) 0 –30 wt. -%of at least one inert mineral filler, all proportions being based on the total weight of the waterproofing layer.
The roofing membrane according to any one of previous claims characterized in that it further comprises a layer of fiber material (5) fully embedded into the polyvinylchloride-based membrane (2) or covering at least a portion of the lower major surface of the polyvinylchloride-based membrane (2) .
The roofing membrane according to claim 12, characterized in that the layer of fiber material (5) is a non-woven fabric having a mass per unit area of 15 –300 g/m ², preferably 25 –200 g/m ².
A method for producing a roofing membrane according to any one of previous claims, the method comprising steps of:

I) Providing a polyvinylchloride-based membrane (2) having upper and lower major surfaces,

II) Laminating a connecting layer (4) to the upper major surface of the polyvinylchloride-based membrane (2) , and

III) Laminating a protective layer to the connecting layer (4) such that the connecting layer (4) forms an interlayer between the polyvinylchloride-based membrane (2) and the protective layer (3) .
A roof system comprising a roof underlayment (6) and a roofing membrane (1) according to any one of claims 1-13 adhered to a surface of the roof underlayment (6) by using mechanical or adhesive bonding means.
The roof system according to claim 15, characterized in that the roof underlayment (6) comprises a cover board and/or an insulation board.