DE19725451A1 - Foamed plastic composite especially for use as underroof membrane - Google Patents

Abstract

In the composite comprising a support and a water vapour-permeable plastics layer, the plastics layer is a closed-cell foam. Claimed production is by extrusion of a mixture of the plastic granulate and a chemical foaming agent, followed by laminating the extrudate to a support, the support optionally having a layer of an adhesive on the side facing the extrudate. The process can also include laminating the support and/or plastics foam layer on its outer surface with a reinforcing layer.

Description

The present invention relates to a composite of a carrier layer and a plastic layer, which for Water vapor, but not permeable to liquid water and is used as a roofing membrane, especially for unventilated, thermally insulated steep roof structures consisting of purlins, Beams and rafters, can be used.

Roofing membranes have the task of covering the uncovered roof first of all to protect against rain. After Hard roofing is said to drive in flying snow, spray and Condensation and fine dust particles in the thermal insulation be prevented. At the same time, water vapor is said to be Excess moisture from the building moisture and from inhabited Areas of the roof can originate over the diffusible Thermal insulation and the roofing membrane released to the environment will. The entire, between the rafters installed thermal insulation serve as moisture storage, taking care that the dew point at which Condensation is deposited, not fall below becomes. This can be done by installing an under the roof vapor barrier or brake in the roof structure be prevented.

Does the installed roofing membrane have no or one too low water vapor permeability, so an im Excess moisture on the roof area Condensate the underlay, moisten the thermal insulation and thus u. a. reduce their function.  

From EP 0 169 308 B1 a sarking membrane is known which consists of a polyurethane film, the one side with a Fleece layer is firmly connected and on the other hand exposed. The fleece layer is permeable to water and has when laying the roofing membrane with the roof internal fleece layer a buffer effect for Steam. The external polyurethane film on the roof is only permeable to water vapor and protects the Thermal insulation against outside water and dust. In in practice, however, arise for those in EP 0 169 308 B1 underlays described only slight Water vapor permeability, so that the implementation of the Thermal protection ordinance is difficult.

Another underlay described in DE 34 25 795 C2 is formed from polyester block amides (PEBA) of the hydrophilic type and is designed as a moisture store which can store up to about 120% of its own weight in water. In practice, it has a water vapor permeability of approximately 1000 g / (m ² d), but due to the lack of a non-woven layer, this type of underlay is mechanically very weak and leaks quickly form if the underlay is damaged during laying.

DE 44 37 521 A1 shows that a combination such a PEBA film with a non-woven layer an increased has mechanical strength, but this combination is water-resistant only for a short time and both Layers because of the different Expansion coefficient when absorbing moisture separate from each other. Therefore, DE 44 37 521 A1 tries to this problem while maintaining the high To solve water vapor permeability, that on both Sides of a plastic film serving as a barrier layer Fleece layer is applied. This is supposed to shear forces compensate for moisture absorption and the composite  the roofing membrane. A disadvantage of this Construction is that sufficient strength and Moisture resistance of the roofing membrane only through the three-layer structure can be achieved. The production is compared to that of a two-layer composite sheet therefore more complicated and because of the increased material requirements a third layer economically less favorable.

It is therefore an object of the present invention while avoiding the above disadvantages of the prior art Technology to provide a network that at simple and therefore inexpensive construction and low Material expenditure a high diffusibility for water vapor and has a sufficiently high mechanical strength and can be used as a roofing membrane. Another The task is to develop a method for producing the to provide the composite according to the invention.

The above first object is thereby inventively solved that the composite a support layer and a water vapor permeable, closed-pore foamed Plastic layer comprises. The carrier layer is permeable for water in liquid and gaseous state and confers mechanical strength against stretching, tearing and tear away with a low basis weight. The foaming the plastic layer impermeable to liquid water leads to a compared to the non-foamed plastic significantly increased diffusibility for water vapor simultaneous weight reduction. They also work gas-filled pores as moisture storage and support thus the accelerated diffusion behavior.

Plastic and carrier layer can be directly with each other be laminated, or there may be an additional one Adhesive layer between the two layers. It is also possible to increase the mechanical strength and the anti-slip properties of the composite through a  additional reinforcement layer on the outside of the plastic and / or to increase the backing layer even further. As examples for such a reinforcement layer here are one Mesh reinforcement and a fleece layer called.

The plastic layer of the present invention is preferably 20-150 microns thick, particularly preferably 40-80 microns, and is preferably foamed so that it is 10 to 30% reduced weight (a 10 to 30% lower density) in the Compared to the compact plastic material. Each the smaller the thickness and density, the cheaper the diffusibility and from an economic point of view Material costs, but on the other hand there is also the danger of injuries and holes in the layer increases and increases their mechanical inherent strength is reduced.

The water vapor permeability (according to DIN 53122, climate B) of the plastic layer is preferably 250-1500 g / (m ² d), particularly preferably 500-1000 g / (m ² d). As a result, a moisture gradient existing between the two sides of the composite is quickly compensated for, so that when used as a roofing membrane, condensation of water on the inner side of the composite on the roof side and wetting of the thermal insulation are largely prevented and the implementation of the thermal insulation regulation is facilitated.

The plastic layer consists of one or more water vapor permeable plastics, being as material preferably thermoplastics are used but thermosets can also be used.

In a preferred embodiment, the Plastics selected from polyamide, polyether block amide (PEBA), thermoplastic polyurethane, hydrophilic Metallocene polypropylene, ethylene vinyl alcohol copolymer (EVOH), copolyamide such as polyamide 6 / polyamide 12 copolymer, Copolyesteramide and with polyester and / or polyether  blocked copolymer. A poly is particularly preferred amide-6 / polyamide-66 / polyamide-12 block copolymer. The above Hydrophilic polymers are particularly high Permeability to water vapor and therefore result in further improved properties of the invention Network.

Any suitable materials can be used for the backing layer, e.g. B. hosiery and knitwear, fabrics, paper, films and nonwovens. The backing layer preferably has a basis weight of 20-300 g / m ² , particularly preferably 50-150 g / m ² . With increasing weight per unit area both mechanical strength and material costs increase, and the lighter the carrier layer, the easier the handling of the composite according to the invention during transport and use, for example as a sarking membrane. The thickness of the carrier layer is therefore preferably 0.15 to 1.5 mm, particularly preferably 0.3 to 0.6 mm, in order to keep the density and thus the volume of the composite low for transport and processing while at the same time having sufficient mechanical strength . Even when used as a sarking membrane, it is not necessary for the backing layer to have a moisture-buffering effect, since this is adequately fulfilled by the thermal insulation prescribed today.

In a special embodiment of the invention a nonwoven layer is used as the carrier layer. The Nonwoven layer can be made using different spinning processes oriented random or needle fleece and made of mono and Bicomponent fibers are produced. In a preferred one Embodiment consist of the fibers of the nonwoven layer one or more polymers selected from polyamide, Polyester or polyolefin. It is particularly preferred that the fibers of a polyester core and a polyamide sheath exist, resulting in a particularly high mechanical Strength with low material costs leads.  

It is particularly preferred to make the plastic layer the same material as the fleece layer. In In this case the two layers adhere to each other simplified. In a further preferred embodiment the fleece layer consists of a polymer fiber Polyamide sheath and polyester core and the plastic layer from a (co) polyamide. This makes it particularly high mechanical strength and diffusibility and also a good recyclability achieved because of the low Polyester content of the nonwoven fibers during recycling does not bother.

The plastic layer can contain other components such as Fillers, UV stabilizers, dyes and pigments contain. If the composite according to the invention as Underlay used, it can be advantageous to To darken the plastic layer to such a degree, that it is still translucent. While processing (Laying) the composite then has a low one Glare, but the rafters and beams can because of the thin carrier layer through the composite be recognized, which increases security for the roofer.

The composite is produced according to the invention in a process which comprises the following steps:

• (a) extruding a mixture comprising thermoplastic granules and chemical blowing agent, through a slit-like Nozzle to a foamed plastic layer;
• (b) depositing the extruded, foamed Plastic layer on a carrier layer and Laminating the combination so produced Carrier layer and plastic layer, the Backing layer on top of the plastic layer  facing side if necessary with a Adhesive is provided; and
• (c) optionally laminating the plastic layer and / or the carrier layer with a Reinforcement layer on the outside the plastic layer or the carrier layer.

In this way, a composite according to the invention is formed a carrier layer and a firmly connected water vapor permeable, closed-pore foamed Plastic layer achieved.

Step (a) is preferably carried out in a 3-zone screw, the layer being extruded through a slot die becomes. It is suitable to add the extrusion mixture in the extruder a preferred pressure of 140-160 bar to a temperature heating preferably from 190-230 ° C.

That in step (b) to the filing of Plastic layer subsequent lamination takes place if none Laminate by applying an adhesive to the Plastic layer facing side of the carrier layer is carried out, preferably between rolls that be kept at a temperature of 10-20 ° C. This Conditions are particularly suitable for the formation of open ones To prevent pores in the foamed layer that too Leaks can result in the composite produced.

When laminating in step (b), the Plastic layer and the carrier layer also by means Hot melts or solvent-based adhesives to be concealed. By laminating the extruded Plastic layer with the carrier layer on which the Side facing plastic layer with an adhesive treated, a composite according to the invention is formed. Solvent-based adhesives are liquid as plastisol. After applying the solvent-based adhesive to the  Carrier layer, extrusion and depositing the plastic layer and laminating the combination, the solvents in evaporated a drying tunnel, so that an inventive Verbund emerges.

In the case of the use of hot melt adhesives, this can for example before lamination to the carrier layer sprayed or sprinkled on. The lamination takes place in this case between heating rollers that take place on a Temperature above the melting point of the hot melt adhesive are heated, so that also an inventive Composite is obtained. Hot melt adhesives are made by one low melting point (<180 ° C, often <100 ° C) and a very low melt viscosity combined with high Melt index (MFR) characterized.

The application of an optional reinforcement layer in the Step (c) can be done by laminating a reinforcing layer on the outside of the backing layer before step (a) or after step (b) and / or on the outside Side of the plastic layer after step (b), or through Coextrusion of a reinforcement layer on the outside Side of the plastic layer in step (a).

In a special embodiment, the chemical blowing agent used in the thermoplastic plastic granulate mixture used releases carbon dioxide when heated. The carbon dioxide produced during foaming acts in addition to the formation of the bubbles as a natural flame retardant in the composite produced, so that no additional flame retardants have to be added in order to meet the legal requirements according to DIN 4102 B2 when using the composite as a building material (underlay). For example, an endothermic blowing agent consisting of a thermoplastic copolymer with a high polar content as the carrier material and a mixture of sodium bicarbonate and monosodium citrate as the gas generator can be used (Hydrocerol®, Boehringer Ingelheim). This chemical, endothermic blowing agent releases H ₂ O and CO ₂ when heated and creates a closed foam structure.

The chemical blowing agent is preferred in one proportion of 0.3-2% by weight, particularly preferably 0.3-1% by weight, of the Total weight of extrusion mix used. Will the If the proportion selected is too high, there is a risk of open pores that lead to undesired permeability of the Plastic layer for liquid water can lead. Becomes on the other hand, if the share is too small, then the The proportion of bubbles in the volume of the plastic layer is too low be so that the benefits of increased Water vapor permeability, weight reduction and Moisture storage effect can be reduced.

If the plastic layer is made of a thermoset, can be caused by foaming due to chemical reactions Addition of blowing agents or blowing agents or by adding volatile solvents to the thermoset monomers during the polymerization can be achieved. The plastic layer Thermoset can be done by hot melt adhesive or solvent based Adhesives are laminated with the backing material, and it can optionally further reinforcement layers on the composite thus obtained can be applied.

The composite according to the invention can be used as a roofing membrane for Roof structures, especially for unventilated, thermally insulated pitched roof constructions, which are also fully boarded can be composed of purlins, beams and rafters, be used. In doing so, the association is based on the Rafters and thermal insulation attached that the Base layer on the roof side and the plastic layer is on the roof side outside. In this way, thermal insulation against water penetrating from the outside to prevent soaking protected, on the other hand, moisture can come from inside the roof through the carrier layer of the composite and  diffuse out through the plastic layer without the risk of condensation on the inside of the bond consists.

Because of the high strength of the invention Verbund is an existing roofing membrane the usual loads during installation grown without leaks from cracks or holes are to be feared.

In the following the invention is illustrated by an example explained in more detail.

A composite is formed by applying a foamed layer of polyamide 6 / polyamide 66 / polyamide 12 copolymer (Platamid® H 105 TA 70 from Elf Ato) to a non-woven layer (Colback® CD 70 from Akzo Nobel; fibers made of polyester core with polyamide sheath; basis weight 70 g / m ² ; thickness 0.45 mm; tensile strength MD according to DIN 53857 200 N / 5 cm). For this purpose, the plastic granulate with a proportion of 0.5% by weight of an endothermic blowing agent with CO ₂ release (Hydrocerol® from Boehringer Ingelheim) is extruded with a 3-zone screw with a slot die. The temperature and pressure of the plastic / blowing agent mixture in the 3-zone screw are 205 ° C and 150 bar (15 MPa). The extrudate and the nonwoven web are laminated by rolling between a pair of rolls cooled to 17 ° C., so that a 0.5 mm thick bond is formed.

The composite thus obtained has a maximum tensile force of 270 N / 5 cm (DIN 53354) and a water vapor permeability of 510 g / (m ² d).

The embodiment shows that the invention Compound excellent properties regarding the Water vapor permeability and mechanical properties with at the same time low material and  has manufacturing technology. The height Water vapor permeability facilitates the implementation of the Heat protection regulation when using the network as Underlay, and the high tear resistance does that Leakage occurs even when installed under high loads are unlikely.

Claims (18)

1. Composite comprising a carrier layer and a water vapor permeable plastic layer, characterized in that the plastic layer is foamed closed-pore. 2. Compound according to claim 1, characterized characterized in that the network additionally an Adhesive layer between the backing layer and the Plastic layer comprises. 3. Compound according to claim 1 or 2, characterized characterized in that the composite on the outside Side of the carrier layer and / or plastic layer additionally comprises a reinforcing layer. 4. Compound according to one or more of the preceding Claims, characterized in that the Plastic layer is 20 to 150 microns thick and one opposite the unfoamed plastic by 10 to 30% reduced density owns. 5. Composite according to one or more of the preceding claims, characterized in that the plastic layer has a water vapor permeability of 250 to 1500 g / (m ² d). 6. Compound according to one or more of the preceding Claims, characterized in that the Plastic layer made of one or more plastics, selected from polyamide, polyether block amide, thermoplastic polyurethane, hydrophilic metallocene poly propylene, ethylene-vinyl alcohol copolymer, copolyamide, Copolyesteramide and with polyester and / or polyether blocked copolymer.   7. Composite according to one or more of the preceding claims, characterized in that the carrier layer has a basis weight of 20 to 300 g / m ² and a thickness of 0.15 to 1.5 mm. 8. Compound according to one or more of the preceding Claims, characterized in that the Carrier layer consists of a non-woven layer. 9. The composite according to claim 8, characterized characterized in that the fibers of the nonwoven layer one or more polymers selected from polyamide, Polyester or polyolefin exist. 10. Composite according to claim 9, characterized characterized in that the fibers of a polyester core and a polyamide sheath. 11. The composite according to claim 10, characterized characterized in that the plastic layer from a (Co) polyamide. 12. A method for producing a composite according to one of claims 1 to 11, characterized in that it comprises the steps:

• (a) extruding a blend comprising thermoplastic resin granules and chemical blowing agent through a slot-like die into a foamed plastic layer;
• (b) depositing the extruded, foamed plastic layer on a carrier layer and laminating the combination of carrier layer and plastic layer thus produced, the carrier layer optionally being provided with an adhesive on the side facing the plastic layer; and
• (c) optionally laminating the plastic layer and / or the carrier layer with a reinforcing layer on the outer side of the plastic layer or the carrier layer.

13. The method according to claim 12, characterized characterized in that step (a) in a 3-zone screw is carried out and the plastic layer is extruded via a slot die. 14. The method according to claim 12 or 13, characterized characterized in that the extrusion mixture in the extruder heated to a temperature of 190-230 ° C and under one Pressure of 140-160 bar is set. 15. The method according to one or more of claims 12 to 14, characterized in that the extruded Plastic layer in step (b) without using a Adhesive deposited on the carrier layer and so manufactured combination between at a temperature of 10-20 ° C cooled rollers is laminated. 16. The method according to one or more of claims 12 to 15, characterized in that the chemical Blowing agent releases carbon dioxide when heated. 17. The method according to one or more of claims 12 to 16, characterized in that the chemical Blowing agent in a proportion of 0.3-2 wt .-%, based on the Total weight of the extrusion mixture is used. 18. Use of the composite according to one or more of claims 1 to 11 as a roofing membrane for Roof structures, with the carrier layer on the inside on the roof and the plastic layer is on the roof side outside.