EP2510166B1 - Moisture-adaptive vapour barrier, in particular for heat insulating buildings, and method for producing said type of vapour barrier - Google Patents

Description

The invention relates to a moisture-adaptive vapor barrier according to the preamble of claim 1 and to a manufacturing method for such a vapor barrier.

Moisture-adaptive vapor brakes are characterized in that the water vapor diffusion resistance of the vapor barrier changes as a function of the humidity, specifically in such a way that the water vapor diffusion resistance decreases as the moisture surrounding the vapor barrier increases. The water vapor diffusion resistance is usually measured according to DIN EN ISO 12572: 2001.

Such vapor barriers are primarily used for the production of the airtightness of buildings and, indeed, in connection with thermal insulation systems for buildings. For the thermal insulation of buildings, in particular roofs diffusion-open underlays are usually below the roof formed approximately by bricks, including a thermal barrier coating, such as mineral wool, finally a vapor barrier and including a cladding used. The use of a vapor barrier primarily pursues two intentions. On the one hand, the airtightness of the roof is to be ensured in order to prevent the ingress of cold outside air into the building interior and the escape of warm indoor air from the building, whereby thermal energy losses as well as building damaging, convective moisture inputs are avoidable. Second, the vapor barrier should have a certain barrier effect against water vapor diffusion in order to avoid unwanted moisture entry into the building structure.

Through the use of so-called moisture-adaptive vapor barriers, which are usually present as a film, moisture penetration in the winter is prevented as a result of the moisture-adaptive characteristics of such a film by under winter conditions and therefore dry moisture conditions, the vapor barrier largely closes. If at higher heat radiation in summer and thus under wet conditions compared to winter conditions, the moisture from the timber construction, for example, a roof reacts, the vapor barrier film responds as a result of the comparatively high humidity surrounding the vapor barrier in which it opens as it were due to reduction of the water vapor diffusion resistance, so that a corresponding dehydration is guaranteed.

Polyamide is often used as the material for moisture-adaptive vapor barrier films (cf. DE 195 14 420 C1 , corresponds WO 96/33321 A1 ). With this film, the water vapor diffusion resistance decreases with increasing mean ambient humidity. In this case, the moisture-adaptive properties of this known film-like vapor barrier are adjusted so that they at a mean humidity of the atmosphere surrounding the vapor barrier of 30 to 50%, a water vapor diffusion resistance (s _d - value) of 2-5m diffusion-equivalent air layer thickness and at a humidity of the environment in the range of 60-80% has a water vapor diffusion resistance (s _d - value), which is smaller than 1m. This has the consequence that such a vapor barrier at winter time, in which there are usually dry conditions and the relative humidity of the atmosphere surrounding the vapor brake is substantially in the range of 30 to 50%, the vapor barrier acts so far as braking as a result of comparatively high water vapor diffusion resistance closes the vapor barrier, so only a little water vapor can diffuse through the film. This prevents any significant moisture from the interior of buildings passes through the film to the outside, for example in a wooden structure of a building roof and / or a wall, where the moisture is then reflected and can eventually lead to rot and mold.

However, under humid conditions, as prevalent in summer months in particular, it is possible to diffuse the moisture due to the reduced diffusion resistance. This has the consequence that now moisture can be removed from the timber construction, so a drying out is made possible, so that damage can be avoided in particular to the wooden structure. Finally, further vapor barrier films in the multi-layer structure with moisture-adaptive characteristics are known (US Pat. DE 20 2004 019 654 U1 respectively. DE 101 11 319 A1 ), which at a relative ambient humidity of 30 to 50%, have a water vapor diffusion resistance s _d of 5 m diffusion-equivalent air layer thickness and above and at a relative ambient humidity of 60 to 80% a water vapor diffusion resistance s _d of less than 0.5 m diffusion-equivalent air layer thickness. In such known moisture-adaptive vapor barrier films, the water vapor diffusion resistance, plotted against the mean or relative humidity in the manner of an S-curve with incoming S-leg, changes from higher water vapor diffusion resistance values at lower humidity in the direction of expiring S-legs with reduced diffusion resistance values higher, the moisture barrier surrounding the vapor barrier.

As is known, the curve diffusion resistance over moisture of the moisture-adaptive vapor brakes can be set via the formula s _d = D x μ, where D indicates the thickness of the vapor barrier and μ represents a material-dependent parameter of the vapor barrier. Thus, although a change in the moisture-adaptive character of a vapor barrier over a corresponding thickness setting is possible, ie the thickness of the vapor barrier film is increased or decreased accordingly, but this does not change the S-curve, but only leads to a shift of the S-curve along the ordinate , This would lead to an increase in the thickness of the vapor barrier to a corresponding increase in the s _d value both under dry conditions in winter and in humid conditions in summer, but in such a case for summer conditions to a deterioration of the properties of the vapor barrier due to thus reduced dehydration behavior would result. A reduction in the thickness of the vapor barrier film, which are usually present in thicknesses in the range of 20 .mu.m to 80 .mu.m, however, limits are set for reasons of strength and stability.

Although the known vapor barrier films have proven suitable for normal conditions, these are, in particular, dry environmental conditions, as generally known in the art Offices prevail, as well as under normal humidity conditions, as prevail especially in residential buildings, however, the behavior of the known vapor barrier films under increased moisture load, especially under colder weather conditions quite problematic. An increased moisture load is especially in rooms, such as commercial kitchens, canteens and the like, but also in living and office space, in which a lot of plants and / or aquariums and the like are housed. An increased moisture load is especially in new buildings and in the renovation of old buildings due to mortar or screed. Due to modern building materials and new construction methods such construction measures are more and more carried out in the colder months, especially in the months of October to March, in times where the ambient humidity settles to a relatively dry value, in which the vapor barrier films among such close normal conditions. However, in the event of a damp load, in particular when carrying out construction work in the colder season, conventional vapor dampers can open the foil due to the ambient humidity on the vapor barrier film and thus a largely unimpeded entry of the moisture through the vapor barrier foil into the wooden structure come, which to a certain extent is extremely critical and can lead to damage in the timber construction in consequence mold and the like.

The object of the invention is to propose a vapor barrier and a manufacturing method for such a vapor barrier, which takes into account the previously described conditions, in particular in the cold season, i. at high humidity load a critical discharge of moisture by the vapor barrier film substantially prevented.

This object is achieved by the measures contained in the characterizing part of claim 1, wherein expedient developments of the invention are characterized by the features contained in the dependent claims. According to the invention, the vapor barrier, which is preferably in the form of a film, is characterized in that it is formed from a material which has a three-part moisture profile, namely from an average relative humidity of 75%, preferably above 70%, and above an s _d value less than 1 m, preferably less than 0.8 m diffusion-equivalent air layer thickness, then with decreasing mean moisture in a range of 45 to 58%, preferably in a range of 40 to 58% has a substantially plateau-like or approximately plateau-like course of the s _d value, over this range a lower s _d value of 2 m and an upper s _d value of 5 m is not exceeded and the difference between the lower and the upper actual s _d value does not exceed 1 m in this range. With further decreasing moisture in a range of 20 to 30%, preferably 20 to 35%, the vapor barrier has an s _d value which is at least 0.5 m above the upper actual s _d value in the plateau-like central region.

Thus, the vapor barrier film from the viewpoint of building physics imperatively small barrier effect in the range of high average humidity greater than 75%, in particular 75%, ie a high dehydration behavior in summer. At the same time, the vapor barrier film in particular satisfies the criterion that at high moisture loads in rooms, such as occur in large kitchens, canteens and the like or construction work in cold seasons, although a certain discharge of moisture, but nevertheless the discharge of moisture compared to conventional vapor barriers reduced accordingly, so that a critical entry of moisture in a wooden structure and the like is avoided in such situations. Under high moisture load thus opens the vapor barrier film with increasing humidity in the specified range of 45 to 58% or 40 to 58%, but the change in the s _d value in this humidity range is only to a lesser extent than in conventional vapor barrier films vonstatten so that In the specified range, a certain holding phase of the change in the s _d values of the vapor barrier film occurs, such that the s _d values of the vapor barrier film change only gradually in this area, but otherwise in principle almost or approximately substantially constant ratios with respect to s _d values are guaranteed in this area. Prefers For example, the curve of the s _d value over the humidity in the range of 45 to 58%, preferably from 40 to 58%, has a substantially plateau-like course, ie the change in the s _d value in this region is over a longer time due to the increased moisture load certain period out kept low, so that on the one hand a certain desired barrier effect of the vapor barrier film is maintained and nevertheless with excessive moisture entry a certain Hindiffdiffundieren of moisture is possible, however, without a critical moisture removal is achieved, as is the case with conventional vapor barrier films at such moisture loads Case would be.

The usual course of the s _d values over the moisture values of conventional vapor barrier films is reflected in a substantially S-shaped curve, whereas in the case of the vapor barrier film according to the invention the curve shape is preferably in the form of a double S curve, the outgoing region of the S Curve in the dry area with the incoming value of the S-curve for the wet area coincides and in the range of a humidity of 45 to 58% and 40 to 58% of the curve almost constant or substantially plateau-like, ie only with a small change in the s _d values occur. In an expedient embodiment of the invention, the course of the curve of the curve changes inside the substantially plateau like area around a s _d -Differenzwert corresponding to the difference of s _d -value when entering the humidity of 45% over the s _d value during the extension the curve at a humidity of 58% by a maximum of 0.6m, preferably a maximum of 0.4m diffusion-equivalent air layer thickness. That is, the vapor barrier film changes its s _d value only gradually within this range, so that a corresponding holding phase is achieved in which the vapor barrier film still largely blocks, but allows a certain moisture discharge within the parameters already mentioned above. The plateau-like profile of the curve of the s _d values above the moisture is preferably within a range of 3 to 5 m diffusion-equivalent air layer thickness.

According to an expedient specification of the invention, the material which determines the moisture adaptivity of the vapor barrier is present in a single layer or layer, the total is formed from this material, in contrast to conventional vapor barrier films, in which the moisture adaptivity is determined by a plurality of superimposed layers of a vapor barrier film.

The plateau-like curve of the s _d values or the described holding phase with only a small change in the s _d values in the humidity range from 45 to 58% or 40 to 58% is achieved by adding an additive to the base material of the vapor barrier, wherein the admixture 10 to 20%, preferably 15 to 20%, (weight percent) compared to the remaining material of the vapor barrier film. The base material of the vapor barrier film is preferably polyamide, wherein as a preferred additive modified polyolefins, in particular a grafted polyethylene copolymer is used. Such grafted polyethylene copolymers are offered by various manufacturers. The types marketed under the brand names Bynel® by Du Pont have proven particularly suitable. Another preferred additive is polyethylenepolyacrylic acid copolymers also offered by various manufacturers. The types marketed under the brand names Surlyn® by Du Pont have proven particularly suitable.

The layer responsible for the moisture acceptability of the vapor barrier film is characterized by a homogeneous layer structure, which is mainly due to a chemical mixing of a compound from the present in granular polyamide and the also present in granular form additive by melting the granular mixture, said melt from polyamide and additive granules are formed, from which then the vapor barrier film is extruded or produced by a blowing process. It is expedient here for the additive to be present in the form of nanoparticles within the starting granulate of the additive.

In accordance with the invention can be vapor barrier films with this described humidity aptitude in a thickness range of, in particular 40 to 80 microns, preferably 50 to 70μm produce. In the context of the invention, it is the case that this single-layer vapor barrier film, as far as the moisture-adaptive character is concerned, is supplemented by further suitable layers, which are provided either to reinforce the film or to influence other properties of the vapor barrier film, depending on the application.

A suitable method for producing such a vapor barrier film is characterized in that starting from granules of polyamide and an additive present in granular form, in particular polyethylene, a compound is formed by mixing. This compound from granular raw materials is melted in a suitable mixing ratio in an extruder, optionally with the addition of other auxiliaries such as homogenizing agents, with the aim to create a homogeneous melt of the above-mentioned starting materials. From the homogeneous melt a mixed granulate is produced. This mixed granulate is further processed in an independent process step in an extrusion process or a blown process into a single-layer vapor barrier film or monofilm according to the invention. A vapor barrier film produced in this way is characterized by a substantially homogeneous structure. Alternatively, the starting materials can also be further processed directly in a suitable extruder and into a corresponding monofilm. The alternative method is preferred because of the unnecessary precompounding from an economic point of view, the required homogenization of the melt is difficult to ensure in the production reality to the desired extent.

The monofilm produced by this process can be provided in known Kaschierverfahren with other layers, in particular to improve their mechanical properties. These additional layers preferably have no effect on the inventive moisture-adaptive character of the film, which is determined by the monofilm.

The mixing ratio of polyamide and additive is adjusted with a view to the desired adaptive humidity characteristic. It has been found in practical experiments that, depending on the individual additive added to a polyamide base, an admixture of the additive to polyamide base in the amount of 7 to 25% is advantageous both for the achievement of the desired adaptive moisture characteristics according to the invention as well in terms of manufacturability of the film. Particularly preferred is an admixture of the additive in the range of 10 to 20%, in particular 14 to 18%, with very good results were achieved with an admixture in the range of 15 to 18%. The upper limits of the admixture of the additive are due to the substance in the range of about 20 to 25% by weight, with a focus on the manufacturability of the film according to the invention a limit of 25% by weight should not be exceeded and the manufacturability of the film is the better, the more the upper range limit shifts downwards towards 20% and below.

Hereinafter, preferred embodiments of the invention are explained with reference to the single figure, which is a graph of curves of four vapor barrier films according to the invention with respect to the s _d values on the average relative humidity, ie the ambient humidity around the vapor barrier film.

The curves K1, K2, K3 and K4 show four vapor barrier films, each in one layer and made of polyamide here with the additive Bynel® 4157 with 20% by weight, and a thickness of 40 microns (K1: 40μm / 20% / B), a Aggregate content of 15% by weight Bynel at a layer thickness of 70 μm (K2: 70 μm / 15% / B), an aggregate content of 18% by weight Surlyn® 1605 at a layer thickness of 60 μm (K3: 60 μm / 18% / S) or here with the additive EVOH Type H171B (manufacturer EVAL Europe) of 15% by weight with a layer thickness of 50 μm (K4: 50 μm / 15% / EVOH).

For ease of manufacture, the upper limits for Bynel 4157 were about 22% by weight, for Surlyn 1605 about 20% by weight, and for EVOH Type H171B about 20% by weight.

Obviously, the humidity adaptivity of the vapor barrier is defined by three areas, each of which determines a rectangular frame. From a humidity of 75%, a rectangular area I with s _d values of less than 1 m diffusion-equivalent air layer thickness is clamped. In the humidity range of 45 to 58% s _d values in the range of 2 to about 4.3 m diffusion-equivalent air layer thickness are given, resulting in a spanned rectangle for the area II within which a second rectangle is spanned, which is the difference of at most 1m in diffusion-equivalent air layer thickness between the lower actual value and the upper actual value in region II. At dry, low humidity in a range of 20 to 30%, the s _d values of the vapor barrier film are in an s _d value range, the lower limit of which is at least 0.5m above the upper actual value in region II, thus providing an upwardly hatched hatched area III is stretched.

The moisture profile of the curve K is spanned by measuring points distributed over the abscissa, the measurement being carried out in accordance with DIN EN ISO 12572: 2001. In test series it has been found that for a precise determination of a single measurement point in the handling area, ie at a steeper curve in known wet-adaptive vapor brakes with a single S-curve curve at medium humidities of about 35 to 65%, a small gradient between should be set to the moisture applied to both sides of the vapor barrier, from which the mean moisture is determined by averaging. Too large gradients lead to falsifications of the measured values, which are reflected in too low s _d values. As usual, a moisture is given by a salt or water, the other side by the setting of a controllable climate chamber.

Table 1 summarizes the humidity settings and the measured values for the exemplary embodiments K1, K2, K3 and K4 according to the invention. Table 1: Humidity conditions for s <sub> d </ sub> value measurement and s <sub> d </ sub> values in m salt climatic chamber Average K1 s _d - value K2 s _d - value K3 s _d - value K4 s _d - value [m] [m] [m] [m] Silica gel: 2% 26% 14% - - - 9.75 Silica gel: 2% 40% 21% - - - 8.94 Silica gel: 2% 53% 27.5% 3.77 6.20 5.96 7.16 Magnesium Nitrate 6 Hydrate: 53% 20% 36.5% 3.10 5.20 4.33 5.67 Magnesium Nitrate 6 Hydrate: 53% 40% 46.5% 2.36 3.58 3.54 3.85 Magnesium Nitrate 6 Hydrate: 53% 62% 57.5% 2.12 3.18 3.3 3.25 Sodium chloride: 75% 50% 62.5% 1.22 1.75 2.15 2.74 Water: 100% 50% 75% 0.33 0.47 0.4 1.84 Water: 100% 60% 80% 0.25 0.38 0.34 0.24

The course of the curves K1, K2, K3 and K4 can be described with a double S-profile, wherein the outgoing leg of the curve in the dry moisture range within the range II merges into the incoming leg of the S-curve for the moister section and can be seen within the area II only a gradual reduction of the s _d values takes place, causing it to a certain holding phase and thus comes approximately to a quasi-constant course with plateauartigem character and within this humidity range, the s _d -values change only gradually, ie the tendency in the direction of opening the vapor barrier film in area II is reduced accordingly. In order to confirm the double-S course, additional MMeasurement points at low mean humidities of 14% and 21% were additionally determined for the exemplary embodiment K4.

A double S-curve is mathematically described by the following equation: $$y\left(x\right)=\frac{A1}{1+e^{B1\left(x-C1\right)}}+\frac{A2}{1+e^{B2\left(x-C2\right)}}+D$$

The parameters A1 / A2 stand for the spreading of the two individual S-curves between minimum and maximum ordinate value, B1 / B2 indicate the spread of the turnover region, i. the steepness of the S-curve, C1 / C2 defines the position of the inflection point of the S-curves, D the lower limit value.

$$\frac{\mathit{dS}}{\mathit{dA}1\dots D}=2\cdot {\displaystyle \sum _{i=1}^n}\left[\left[y_i\left(x_i\right)-y\left(x_i\right)\right]\cdot \frac{dy}{dA\mathrm{1....}D}\right]\stackrel{!}{=}0,$$

mit $$\frac{dy}{dA1}=\frac{1}{1+e^{B1\cdot \left(x_i-C1\right)}}\mathrm{und}\frac{dy}{dA2}=\frac{1}{1+e^{B2\cdot \left(x_i-C2\right)}}$$

$$\frac{dy}{dB1}=\frac{-1}{{\left(1+e^{B1\cdot \left(x_i-C1\right)}\right)}^2}\cdot \left(x_i-C1\right)\cdot e^{B1\cdot \left(x_i-C1\right)}\mathrm{und}\frac{dy}{dB2}=\frac{-1}{{\left(1+e^{B2\cdot \left(x_i-C2\right)}\right)}^2}\cdot \left(x_i-C2\right)\cdot e^{B2\cdot \left(x_i-C2\right)}$$

$$\frac{dy}{dC1}=\frac{1}{{\left(1+e^{B1\cdot \left(x_i-C1\right)}\right)}^2}\cdot B1\cdot e^{B1\cdot \left(x_i-C1\right)}\mathrm{und}\frac{dy}{dC2}=\frac{-1}{{\left(1+e^{B2\cdot \left(x_i-C2\right)}\right)}^2}\cdot B2\cdot e^{B2\cdot \left(x_i-C2\right)}$$

$$\frac{dy}{dD}=1$$

Using the least-squares method for the regression yields: $$S={\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}{\left[y_i\left(x_i\right)-\mathrm{<figure-callout\; id="2"\; label="y\; x\; i"\; filenames="imgf0001.png"\; state="\{\{state\}\}">y\; </figure-callout>}\left(x_i\right)\left({}_{}\right)\right]}^2\to \min$$

$$\frac{\mathit{dS}}{\mathit{there}1...D}=2\cdot {\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}\left[\left[y_i\left(x_i\right)-y\left(x_i\right)\right]\cdot \frac{dy}{dA\mathrm{1....}D}\right]\stackrel{!}{=}0.$$

With $$\frac{dy}{dA1}=\frac{1}{1+e^{B1\cdot \left(x_i-C1\right)}}\mathrm{and}\frac{dy}{dA2}=\frac{1}{1+e^{B2\cdot \left(x_i-C2\right)}}$$

$$\frac{dy}{dB1}=\frac{-1}{{\left(1+e^{B1\cdot \left(x_i-C1\right)}\right)}^2}\cdot \left(x_i-C1\right)\cdot e^{B1\cdot \left(x_i-C1\right)}\mathrm{and}\frac{dy}{dB2}=\frac{-1}{{\left(1+e^{B2\cdot \left(x_i-C2\right)}\right)}^2}\cdot \left(x_i-C2\right)\cdot e^{B2\cdot \left(x_i-C2\right)}$$

$$\frac{dy}{dC1}=\frac{1}{{\left(1+e^{B1\cdot \left(x_i-C1\right)}\right)}^2}\cdot B1\cdot e^{B1\cdot \left(x_i-C1\right)}\mathrm{and}\frac{dy}{dC2}=\frac{-1}{{\left(1+e^{B2\cdot \left(x_i-C2\right)}\right)}^2}\cdot B2\cdot e^{B2\cdot \left(x_i-C2\right)}$$

$$\frac{dy}{dD}=1$$

1. 1)
   
2. 2) $${\displaystyle \sum _{i=1}^n}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{1}{1+e^{B2\cdot \left(x_i-C2\right)}}\right]=0$$
   
3. 3) $${\displaystyle \sum _{i=1}^n}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{-1}{{\left(1+e^{B1\cdot \left(x_i-C1\right)}\right)}^2}\cdot \left(x_i-C1\right)\cdot e^{B1\cdot \left(x_i-C1\right)}\right]=0$$
   
4. 4) $${\displaystyle \sum _{i=1}^n}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{-1}{{\left(1+e^{B2\cdot \left(x_i-C2\right)}\right)}^2}\cdot \left(x_i-C2\right)\cdot e^{B2\cdot \left(x_i-C2\right)}\right]=0$$
   
5. 5) $${\displaystyle \sum _{i=1}^n}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{-1}{{\left(1+e^{B1\cdot \left(x_i-C1\right)}\right)}^2}\cdot B1\cdot e^{B1\cdot \left(x_i-C1\right)}\right]=0$$
   
6. 6) $${\displaystyle \sum _{i=1}^n}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{-1}{{\left(1+e^{B2\cdot \left(x_i-C2\right)}\right)}^2}\cdot B2\cdot e^{B2\cdot \left(x_i-C2\right)}\right]=0$$
   
7. 7) $${\displaystyle \sum _{i=1}^n}[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]=0$$
   

Thus, 7 equations are used for the determination of the curve parameters A1 to D

1. 1)
   
2. 2) $${\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{1}{1+e^{B2\cdot \left(x_i-C2\right)}}\right]=0$$
   
3. 3) $${\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{-1}{{\left(1+e^{B1\cdot \left(x_i-C1\right)}\right)}^2}\cdot \left(x_i-C1\right)\cdot e^{B1\cdot \left(x_i-C1\right)}\right]=0$$
   
4. 4) $${\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{-1}{{\left(1+e^{B2\cdot \left(x_i-C2\right)}\right)}^2}\cdot \left(x_i-C2\right)\cdot e^{B2\cdot \left(x_i-C2\right)}\right]=0$$
   
5. 5) $${\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{-1}{{\left(1+e^{B1\cdot \left(x_i-C1\right)}\right)}^2}\cdot B1\cdot e^{B1\cdot \left(x_i-C1\right)}\right]=0$$
   
6. 6) $${\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}\left[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]\cdot \frac{-1}{{\left(1+e^{B2\cdot \left(x_i-C2\right)}\right)}^2}\cdot B2\cdot e^{B2\cdot \left(x_i-C2\right)}\right]=0$$
   
7. 7) $${\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}[\left[y_i\left(x_i\right)-\left(\frac{A1}{1+e^{B1\cdot \left(x_i-C1\right)}}+\frac{A2}{1+e^{B2\cdot \left(x_i-C2\right)}}+D\right)\right]=0$$
   

This equation system is not closed solvable. It is usually calculated using an iterative method starting from suitable starting values.

For the three curves K1, K2 and K3, the following values result as "best fit": A1 A2 B1 B2 C1 C2 D K1 3.5 2.0 0.20 0.48 25 62 0.29 K2 6.3 3.2 0.23 0.44 25 62 0.36 K3 2.5 3.2 0.4 0.41 34 63 0.35 K4 6.7 3.3 0.15 0.5 30 62 0.2 iteration 0.1 0.1 0.01 0.01 0.5 0.5 0.01

As the embodiments prove, the course of the curve K can of course be influenced by the layer thickness and a corresponding admixture of the additive, wherein, as already stated above, preferably Bynel®, e.g. Bynel® 4157, or Surlyn®, e.g. Surlyn® 1605, or EVOH, e.g. H171B is used.

The vapor barrier films K1 and K2 were produced from a granulate mixture of polyamide with about 15% or 20% Bynel® 4157, whereby this granulate mixture is melted and from the melt again a granulate of a mixture of polyamide and Bynel® 4157 is formed. From this granulate, a vapor barrier film with a thickness of 70 μm or 40 μm was then produced by conventional extrusion in an extruder. The vapor barrier film K3 was produced in an analogous manner with the addition of 18% Surlyn® 1605. A product thickness of 60 μm was produced. The vapor barrier film K4 was prepared via a mixture of polyamide with addition of 15% EVOH H171B in an extruder with attached slot die. A product thickness of 50 μm was produced.

In all embodiments, a polyamide 6 was used, namely the type B40L (manufacturer BASF).

Practical experiments have shown that the vapor barrier films according to the invention, in particular under moist conditions, such as those found in construction projects in the context of new buildings or renovations, still develops a desired barrier effect in the critical humidity range of 45 to 60% and only slightly opens in the stated range, see above that over a longer period of time a largely uniform and not harmful to the wood construction moisture discharge takes place through the vapor barrier film

Claims (17)

1. A moisture adaptive vapour barrier, in particular for use in the thermal insulation of buildings, which has a resistance to water-vapour diffusion (s_d value) expressed as a diffusion equivalent air layer thickness (s_d value), which increases with decreasing moisture of the moisture surrounding the vapour barrier, whereas
   the vapour barrier has an s_d value of less than 1m, preferably less than 0.8m in a region (I) from an average relative moisture of 75%, preferably 70% and more, and
   characterized in that
   the vapour barrier has an essentially plateau-like or approximately plateau-like course at an average moisture in a region (II) from 45 to 58%, preferably in a region from 40 to 58%, whereas over this region, a lower s_d value of 2 m is not undershot and an upper s_d value of 5 m is not overshot and the difference between the upper and the lower actual s_d value does not exceed 1m, and
   has an s_d value that is at least 0.5 m above the actual upper s_d value in the plateau-like central region in case of an average moisture in a region (III) from 20 to 30%, preferably 20 to 35%.
2. The vapour barrier according to claim 1,
   characterized in that
   the plateau-like course of the curve of the s_d value takes place within a region (II) from 3 to 5 m diffusion equivalent air layer thickness.
3. The vapour barrier according to claim 1 or 2,
   characterized in that
   the course of the curve changes within the essentially plateau-like region (II) by a s_d difference value of at most 0.6 m, preferably at most 0.4 m diffusion equivalent air layer thickness, in particular decreases with an increase in moisture.
4. The vapour barrier according to one of the preceding claims,
   characterized in that
   the s_d values of the vapour barrier are less than 0.5 m diffusion equivalent air layer thickness with a moisture starting from 75%, preferably a moisture starting from 70% and more.
5. The vapour barrier according to one of the preceding claims,
   characterized in that
   the curve of the s_d values of the vapour barrier lies over the moisture essentially in sort of a doubleS-curve, with the plateau-like region being essentially in the transition area of the subsequent S-curves.
6. The vapour barrier according to one of the preceding claims,
   characterized in that
   the material which determines the moisture adaptivity of the vapour barrier is present in one, i.e. in a single layer.
7. The vapour barrier according to claim 5,
   characterized in that
   the material of the vapour barrier is made of polyamide with an admixed additive.
8. The vapour barrier according to claim 7,
   characterized in that
   the amount of the additive to the material of the layer is 10 to 20%, preferably 15 to 20%, measured in weight percent.
9. The vapour barrier according to claim 7 or 8,
   characterized in that
   the additive is made of a modified polyolefin, in particular of a grafted polyethylene polymer, preferably bynel, or of a polyethylene polyacrylic acid copolymer, preferably Surlyn (trademark name of Dupont).
10. The vapour barrier according to one of the claims 6 to 9,
    characterized in that
    the material of the layer for forming an essentially homogeneous layer structure is made out of polyamide granules and the additive which is available in form of granules, which are extruded to a foil-like layer after mixing.
11. The vapour barrier according to one of the claims 6 to 9,
    characterized in that
    the material of the layer for forming an essentially homogeneous layer structure is made of polyamid egranules and the additive which is available in form of granules, which are chemically mixed after mixture to a compound and after fusion of the compound, and which are formed as polyamide and the granule-containing additive and which are present in the vapour barrier as an extruded or blown foil-like layer.
12. The vapour barrier according to claim 10 or 11,
    characterized in that
    the additive is available in form of nano particles within the basic granules of the additive.
13. The vapour barrier according to one of the preceding claims,
    characterized in that
    the material layer is formed by a foil with a thickness of 40 to 80 µm, preferably a thickness of 50 to 70 µm.
14. A method for producing a moisture adaptive vapour barrier according to one of the preceding claims,
    characterized in that
    granules of polyamid are mixed with granules of an additive, in particular polyethylene polymers and that from this mixture, the vapour barrier is formed by extrusion or a blow process.
15. The method according to claim 14,
    characterized in that
    the granules are melted on for the chemical mixing, so that granules out of a mixture of polyamide and additive are formed from this melt, and that the vapour barrier is formed from these granules by extrusion or a blow process.
16. Method according to claim 14 or 15,
    characterized in that
    the additive in the basic granules of the additive is available in nano particle size.
17. Method according to claim 14 or 15,
    characterized in that
    the vapour barrier is formed to a foil with a homogeneous mixed structure out of polyamide and additive.

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