The invention relates to a self-adhesive, expandable sealing tape according to the preamble of claim 1 , and to a blank from such a sealing tape, and to a method for producing an air-tight seal.

Such adhesive or sealing tapes are used to seal penetrations, such as pipelines, chimneys or line sections, through plastic sheets, in particular vapor barrier sheets or even underlay webs. A problematic issue with vapor barriers are regions which, owing to local conditions, have to be provided with larger openings in order to provide a passage for pipelines, chimneys or other bodies which must penetrate the sheet. The difficulty which arises in this case is that of completely sealing the vapor barrier again so that the transition regions between the penetrating body and the vapor barrier are once again air-tight. In particular, when there is a non- perpendicular angle between the penetrating body and particularly when same has a circular contour, this problem becomes relevant in practice.

A routine procedure in the field of construction is, in such a case, to adhere the vapor barrier to the penetrating body using adhesive tapes. Using this procedure, a high level of sealing tightness cannot be achieved. Particularly when a plurality of such penetrations with adhesive are present, the leakage flows add up, and so considerable heat losses and/or failure of a blower door test as a criterion for the air- sealing tightness of the overall structure can occur. In order for the vapor barrier or dampproof membrane to have its desired effect, the sheet of the vapor barrier or dampproof membrane must also be sealed in an air-tight manner in those regions where it is penetrated by installations such as pipelines and the like which are guided through the vapor barrier or dampproof membrane sheets. For this purpose, the sheet is to be cut around the region of the penetrating body. The thus produced opening is now covered with adhesive tape or conventional sleeve devices.

In order to achieve air-sealing tightness of buildings in the region of installation penetrations, e.g. in the slanted roof space of a building, different air seal sleeves are known. For instance, DE 10 2004 038 687 B4 describes an air seal sleeve for installation penetrations in buildings having a sealing tarpaulin and a sealing collar. Provision is made that the sealing tarpaulin and the sealing collar are formed in two parts and are fixed to one another obliquely at a predetermined angle. As a result, the air seal sleeve can also be simply attached to already mounted installations by subsequently wrapping the sealing collar around the finished installation and the sealing tarpaulin is applied to the substantially planar surface which is to be sealed. For this purpose, the sealing tarpaulin and the sealing collar are each formed from a flat blank. In order to facilitate mounting of this air seal sleeve, an adhesive strip is applied to the rear side of the sealing tarpaulin. This rear side of the sealing tarpaulin is, in use, applied to the planar surface and is sealed to the outside. The sealing collar can also have an adhesive strip so that the sealing collar can be easily fixed to the installation, e.g. a pipe, cable or line.

Finally, a sleeve device for an air-tight seal of a vapor barrier or dampproof membrane is known from DE 10 2009 060 673 A1 which is likewise designed for installation penetrations in buildings and provides a first surface element for arranging the device on the vapor barrier or dampproof membrane at the penetration region, having a hole region arranged in the center, wherein a hose-like element is placed onto the first surface element for surrounding the penetration and a first end of the hose-like element issues into the hole region of the first surface element. In so doing, the first surface element is supported partly on a support region of the hose- like element, thus permitting air-tight sealing of a vapor barrier or dampproof membrane. A disadvantage of this sleeve device is that of putting the hose-like element over the body penetrating the vapor barrier or dampproof membrane. In the case of pipelines or pipes which extend over the entire height of the room and are already installed, this device cannot be attached because these sleeves do not have a slot and thus must be pushed from an open end of the line to the air-tight plane. The main place of installation for these sleeves is thus the outer roof. Such sleeves are very expensive, which is also a disadvantage. Furthermore, the hose-like element can only be used for a particular pipe size. For other pipe diameters, separately formed hose-like elements with a different diameter must be used.

A further sealing sleeve for a pipe penetration on a building inclined surface is known from DE 10 2018 113 284 A1. In this sleeve device, the end face of the sleeve pipe facing the building is provided with straps through notches so that the sleeve pipe can be placed on the roofing membrane of the inclined surface or the slanted roof, after the sleeve pipe has been placed or wrapped around the pipe. Then, two sheet blanks are placed on the roofing membrane for forming the sleeve part, specifically on the straps of the sleeve pipe, wherein mutually facing cut-outs of the two blanks embrace the pipe accordingly. In a further step, the overlapping blanks are adhered to each other and to the roofing membrane, specifically using an adhesive tape. A disadvantage here is that altogether four parts are required for producing the sleeve device, namely two blanks for a sleeve part, the sleeve pipe and an adhesive tape. This complicates attachment in practice. Owing to the numerous overlapping joints, multiple adhesive tape sections must be cut from an adhesive tape roll and each adhered to the multiplicity of overlapping joints, which renders the attachment of the sealing sleeve to the penetration and the building inclined surface time-consuming.

A specific sealing solution using a wide adhesive tape and a specific sectional template is disclosed in DE 10 2017 011 813 for solving this sealing problem, which makes provision for a method for the air-tight sealing of a vapor barrier or dampproof membrane at a penetration region, at which the vapor barrier or dampproof membrane is penetrated by a body which is in particular circular in cross-section. This improves the conventional methods of adhering with standard adhesive tapes, such as e.g. in accordance with DE 10 2009 060 673 A1. However, this solution is very time consuming, owing to a large number of steps which are required for attaching the adhesive tape.

The sealing of penetration regions with flexible adhesive tapes is also known, see DE 101 51 731 A1. A disadvantage of this solution is that the adhesive tape can become detached from the sheet over time owing to return forces, and so one or more unsealed points can arise in the seal.

Proceeding from the above-mentioned prior art, the object of the invention is to prevent, using simple measures, detachment of a seal, in particular a sealing tape, from penetrations through a synthetic sheet owing to overexpansion. A further object of the invention is to ensure permanent adhesion of the seal. Furthermore, the seal should withstand any return forces.

This object is achieved in accordance with the invention by the features contained in the characterizing part of claim 1 and by a blank from a sealing tape as claimed in claim 14 and by a method as claimed in claim 15, wherein expedient developments of the invention are characterized by the features contained in the dependent claims.

In accordance with the invention, the object is achieved in terms of the device by a self-adhesive, expandable sealing tape which is provided for the air-tight sealing of component penetrations, such as beams or pipes, through synthetic sheets in roofs, buildings and the like, in particular for sealing pipe, chimney and line penetrations through vapor barrier sheets or dampproof membranes. The sealing tape preferably comprises in its longitudinal direction at least one first reference line as a cutting reference line and a second reference line as a folding line for forming a one-piece sealing device, in particular a sealing tape comprising a sealing tape collar and a sealing tape tarpaulin. By using the reference lines, at least one sealing tape blank can be produced which can be applied or attached to an already attached vapor barrier or dampproof membrane (at a point designated for this purpose) for the air- tight sealing of the already attached vapor barrier or dampproof membrane and simultaneously at a region of the penetration located at the penetration point. The first reference line is preferably indicated by a marking, e.g. a continuous line printed thereon, alternatively as a dashed or/and dotted or even colored line. In an expedient manner, the second reference line for forming the sealing blank is provided in a visible manner for the user as a preferable second marking. However, it can also be formed as a non-visible reference line which in the case of the description is defined as lying in the center of the width of the sealing tape.

A distance B1 is located between the second reference line and the first reference line and determines the width of the sealing tape tarpaulin. The sealing tape tarpaulin forms the region of the sealing tape which is placed on an already attached synthetic sheet, in particular a vapor barrier or dampproof membrane. The sealing tape can be attached in such a manner that at least one section of the sealing tape surrounds the penetrating body. This section is referred to as sealing tape collar.

The sealing tape is expediently formed from an expandable, preferably water-tight backing material and an adhesive layer, as will be described in detail hereinafter. The adhesive layer is advantageously covered with a slotted or non-slotted liner, in a particularly preferred manner a liner as a pull-off strip of silicon paper. This prevents inactivation of the adhesive layer owing to contamination. Prior to attaching the sealing tape, the liner is pulled off so that the adhesive layer is exposed and the tape can be fixedly adhered.

By using the distance B ₁ , or the width of the sealing tape tarpaulin, an expansion D _B1 is simultaneously specified at the outer periphery of the sealing tape tarpaulin. With this expansion D _B1 , the sealing tape tarpaulin can be expanded to form a sealing tape fan and is optimally applied, in particular adhered, in a long-lasting manner to the synthetic sheet at the penetration point without excessively large return forces, so that detachment or impairment of the adhesion is reliably avoided. In contrast, the sealing tape collar is attached around the penetration without expansion. The sealing tape consisting of the sealing tape collar and sealing tape tarpaulin is attached in an expedient manner simultaneously or alternatively in a time-delayed manner, after or before cutting the tape to length, wherein firstly the sealing tape collar and the sealing tape tarpaulin are arranged in their correct position at the penetration point (sealing tape collar surrounds penetration, sealing tape tarpaulin lies on sheet), and then the sealing tape collar which is wrapped around the penetration, is adhered and subsequently the sealing tape tarpaulin is expanded in the longitudinal direction and then fixedly adhered to the synthetic sheet. Overexpansion is advantageously prevented owing to the defined distance B ₁ in particular no excessively large return forces are produced which could result in subsequent detachment of the sealing tape.

The expansion D _B1 must be able to be permanently provided by the sealing tape, i.e. it may be smaller than or (at most) equal to a maximum expansion D _max , at which the sealing tape still fulfills the function of permanent, air-tight adhesion. This maximum expansion D _max depends inter alia upon the structural constitution of the sealing tape, the backing/sealing material, the material of the adhesive layer and the thickness thereof. For the purposes of the present application, this maximum expansion is determined as follows for an adhesive tape:

Measuring method for determining D _max and Dm

A sealing tape section of length L of 340 mm and width B of the sealing tape tarpaulin is placed with the sealing tape collar around a pipe having a nominal diameter D100 with an overlapping joint of approximately 2.6 cm. The pipe is arranged centrally in a vapor barrier sheet element of 60 x 60 cm with a circular cut- out having a diameter of 105 cm. The sealing tape tarpaulin of width B is adhered to the vapor barrier sheet element and the outer contour of the sealing tape tarpaulin is marked. In an increasing width B of the sealing tape tarpaulin, five samples are produced in steps of 10 mm beginning with a width B of 20 mm, i.e. in widths of 30 mm, 40 mm, 50 mm, 60 mm...

After two weeks of storage in condition of continuity, the samples are evaluated.

Failed samples are defined using the following criteria:

• Detachment of the outer tape contour at least in partial regions either greater than 10% of the width B or greater than 10 mm in the radial direction, and/or

• Retraction of the outer contour without detachment either by greater than 10% of the width B or greater than 10 mm in the radial direction, and/or

• Detachment of the sealing tape tarpaulin in partial areas.

The maximum expansion D _max is produced from the largest width of the sealing tape tarpaulin without a failed sample according to the following formula: D _max = 1 + B/50 with B in mm

The specified, selected expansion D _B I for setting the reference lines is produced by a safety factor S _F which can be selected to be between 0.6 and 1 . The calculation then occurs as follows: D _B1 = S _F * D _max . Therefore, as an example, with a safety factor S _F of 0.6 and D _max of 70%, the specified expansion D _B I is equal to 42%: D _B1 = 0.6 * 70% = 42%.

It is not necessary to test all samples in all intermediate widths, the crucial aspect is merely the width range of the beginning failure or failure of the sample.

Determination of D _max for an exemplified embodiment in accordance with the invention: D _max was determined for a sealing tape (or strip) of an overall width B ₀ of 150 mm having a structural constitution of a backing material in the form of a PET sheet, an adhesive layer of UV-crosslinked polyacrylate adhesive and a liner covering the adhesive layer. The folding line was set at a distance B ₂ of 50 mm from the first long side (for forming a sealing tape collar).

Five sections each with a length of 340 mm and with strip or tape widths of 70 mm, i.e. 50 mm + 20 mm, from 80 mm up to the original strip width B ₀ of 150 mm were produced in steps of 10 mm.

All strip or tape sections were placed with the 50 mm-wide sealing tape collar section around a pipe having a nominal diameter D100 and adhered thereto, whereby in the sealing tape collar an overlapping joint of approximately 26 mm was produced. The sealing strip tarpaulins were adhered in a fan-like manner to the sheet having dimensions of 600 x 600 mm with a central cut-out having a diameter of 105 mm, wherein the pipe had been arranged centrally in the central cut-out.

The results, determined after storage in condition of continuity, as per the above- defined criteria are summarized in the following Table I.

Table I: Results of sample evaluation for determining the maximum expansion D _max or maximum expansion factor D _max

The maximum expansion factor is thus produced by D _max = 1 + B/50 = 1 + 40/50 = 1 .8, which equates to a maximum expansion D _max of 80%.

For the placement of the first reference lines, a rather large safety factor S _F (in terms of a small value) of approximately 0.9 was selected, from which a rounded “design expansion” of 70% is calculated, which corresponds to the expansion D _B1 .

With preliminary tests, the testing outlay can be reduced, in that superfluous samples - because they have failed - owing to overexpansion are excluded from the outset.

The at least one first reference line, which is formed as a cutting reference line and is advantageously indicated as a first marking, is used to indicate to the user that the tape can be cut along this line to a specific width B ₁ when a specific diameter or circumference of the penetration is cutable. At the second reference line, which is formed as a folding line, the sealing tape or blank is folded. The area provided above the folding line thus forms a sealing tape collar and the area provided beneath the folding line and having a width B ₁ forms a sealing tape plane or sealing tape tarpaulin for adherence to the synthetic sheet or plastic sheet.

In particular, provision is made that the sealing tape tarpaulin and the sealing tape collar, which are separated by the second reference line but are formed as such in one piece, are adhered to the component penetration and the synthetic sheet, wherein the sealing tape collar is placed around the penetration without expansion and is adhered thereto and the sealing tape tarpaulin is arranged on the synthetic sheet with expansion in the longitudinal direction and is adhered thereto. Owing to the expandable material of the sealing tape, the sealing tape is advantageously suitable for installations which penetrate through a surface in an inclined manner, such as in the case of pipes or lines in the slanted roof space. Thus, in the case of a circular penetration, in particular in the case of pipe penetrations in the region of the penetration point in a slanted roof, has the shape of an ellipse, and it is possible to simply attach the sealing tape to the region to be sealed. Owing to the distance B ₁ defined between the first and second reference lines, by means of which distance the expansion D _B1 of the sealing tape, in particular the sealing tape tarpaulin for the respective penetration circumference, is specified, overexpansion of the sealing tape tarpaulin is no longer possible after expansion to form a sealing tape fan. Therefore, without detachment of the adhesive or the adhesive layer from the backing material of the sealing tape, a long-lasting, air-tight sealing of the component penetration is ensured by the sealing tape and the synthetic sheet. Owing to the at least one first reference line and the second reference line, the width of the sealing tape can be cut precisely to any diameter or circumference of a pipe such that the width of the sealing tape, in particular the sealing tape tarpaulin, corresponds to the permissible expansion of the sealing tape which is specified in terms of application aspects and therefore overexpansion when the sealing tape is attached by the user is prevented.

In a preferred embodiment, the distance B ₁ defined between the first and second reference line is between 25 mm and 100 mm. In an expedient manner, the sealing tape has an overall width B ₀ of between 50 mm and 250 mm.

The overall width corresponds to the typical application sizes for air-tight sealing of penetrations in buildings, in particular in the field of heat insulation of buildings. The distance B ₂ defined between a first long side of the sealing tape and the second reference line is at least 25 mm, preferably between 30 mm and 60 mm. The distance of the remaining width B ₃ of the sealing tape, which remains after cutting of the sealing tape to the desired width B ₁ and is discarded, is defined by the distance from the first reference line to the second long side, opposite the first long side, and is at least 10 mm.

In addition to the at least one first reference line, in an expedient manner further first reference lines can be applied to the sealing tape as cutting reference lines, i.e. two or three “first” reference lines or a second “first” reference line, a third “first” reference line etc., and so the same sealing tape can be cut to the correct width depending upon the diameter of differently sized penetrations for long-lasting, air- tight sealing of the penetration region. The one and the same sealing tape can thus be used for several diameters. This permits varied use of the sealing tape on-site at the place of installation.

In an advantageous embodiment, the reference lines, preferably at least the one first reference line, particularly preferably the at least one second reference line and further preferably further reference lines, are provided as a first, second and/or further marking in the form of dashed, dotted and/or continuous lines. The reference lines can in particular have different designs, in an expedient manner also with different line widths and thicknesses. Furthermore, they can be printed on the sealing tape in different colors. In a particularly expedient embodiment of the invention, a slot of a slotted liner or pull-off strip, which is preferably formed from silicon paper, forms the at least one first reference line, wherein the slot consequently extends in this case in a straight line in the longitudinal direction of the tape. The reference lines preferably extend over the entire length of the sealing tape.

In a further advantageous embodiment of the invention, the sealing tape includes at least one third reference line, preferably as a third marking. This third reference line is defined by the second long side of the sealing tape, opposite the first long side. A distance B ₄ is defined between the third reference line and the second reference line. This third reference line may thus be non-visible owing to its definition by the second long side or else may be visible as a third marking, e.g. by dashed, dotted and/or continuous lines, which are preferably printed onto the sealing tape, or the like. A sealing blank is in this case only produced by virtue of the fact that the tape is cut, after measuring the required length, in the widthwise direction to the desired length. A further cut in the longitudinal direction along at least one first reference line is then no longer necessary because the third reference line is the second long side. By means of the second reference line or folding line which is located in the center of the width either visibly or non-visibly or even visibly outside of the center of the width, the sealing tape blank can then be divided into two area sections (each defining the sealing tape collar and the sealing tape tarpaulin) after visual inspection and the sealing tape collar is placed or wrapped around the penetration and the sealing tape tarpaulin is placed on the substantially planar building surface, e.g. the synthetic sheet, in particular dampproof membrane or vapor barrier, which is to be sealed, is expanded (then forming a sealing tape fan) and then both area sections are adhered, wherein in the case of the sealing tape tarpaulin, an expansion up to the expansion D _B 4 defined by B ₄ can occur, thus producing a sealing tape fan and without detachment of the sealing tape from the planar surface occurring after attachment.

A first or third reference line at a width B-, or B ₄ for a specified pipe diameter having a specified expansion D _B 1 or D _B4 guarantees in particular an overexpansion-free sealing for all pipes having a relatively large diameter. This is also apparent from the following calculations.

In accordance with a further embodiment of the invention, a first area of the sealing tape tarpaulin is defined by the distance B ₁ between the first and second reference line or by the distance B ₄ between the second and third reference line and the two opposite long sides of the sealing tape remaining after the sealing tape cut to the required length. The two opposite broad sides of the sealing tape remaining after cutting and the respective long sides delimit the first areas A ₁ or A ₄ wherein the length of the broad sides corresponds in each case to the distance B ₁ or B ₄ and the length of the long sides corresponds to the length required for the penetration size plus a overhang, by means of which an adhesion an overlapping point can be created. In contrast, a second area of the sealing tape collar is delimited by the broad sides, which are defined by the distance B ₂ between the first long side of the sealing tape and the folding line, and the two long sides formed by the first long side and the folding line, which long sides consequently have the same length as the long sides of the first area.

In a particularly expedient embodiment of the invention, the distance B-, or B ₄ between a first and second reference line or between a second and third reference line respectively is dependent on a circumference or radius of the penetration and a maximum expansion D _max of the sealing tape, from which the specified expansion D _B1 or D _B4 is derived, as described above. This is expedient because the self- adhesive and expandable sealing tape must then be air-tight after being attached at the sealing point and the expansion must be stopped before overexpansion of the sealing tape, otherwise the sealing tape becomes detached owing to return forces produced and thus is no longer attached in an air-tight manner. The expansion should also be stopped before the tape has expanded so much that return forces are produced which contract the tape back towards its original size. In this case, the disadvantageous result is detachment of the tape at its edge along the outer curved line of the sealing tape fan. This should be avoided, for which reason the distance designated in this paragraph is defined by the parameters designated herein. Depending upon the circumference or radius of the penetration and the recommended maximum expansion of the sealing tape, the suitable width for the respective circumference of the penetration can be cut using the at least one first reference line or by at least two or more first reference lines or the third reference line.

The distances B ₁ or B ₄ are calculated, in the case of an elliptical cross-section of the penetration at the penetration point, from the mathematical formula shown hereinafter:

The circle of the circular penetration with radius r transitions at the penetration point, e.g. in the case of a roof pitch, into an ellipse with a semimajor axis a and semiminor axis b, as follows: with the line integral of the elliptical arc:

In the case of the ellipse with the following parameters: the arc length S(τ) is calculated as

With b = r and a = the expression is simplified to

For full details, reference is made to textbooks regarding complete and incomplete elliptical integrals. For example, reference is made to Karl Heinrich Schellbach: Die Lehre von den elliptischen Integralen und den Theta-Functionen [the teaching of elliptical integrals and theta functions], De Gruyter, Reprint 2011 , ISBN 978-3-11- 130607-0. Since the function E (τ, sin α) is constant, the maximum expansion is located either at the semiaxis a or the semiaxis b.

The part of the sealing tape attached to the sheet, i.e. the sealing tape tarpaulin or first area having width z thus has an outside radius a) for semiaxis a: b) for semiaxis b: b = r + z

There is no expansion at r or because at that location the sealing tape lies on the penetrating pipe in an unexpanded state.

Because the specific curve is not important when considering the expansion D at merely the two points of the semimajor or semiminor axes, a circular circumference is applied for the sake of convenience.

The circumference is thus calculated at the pipe for the semimajor axis as the outer periphery of the sealing tape is calculated as a function of the tape width z as

Therefore, the expansion factor Δ is determined as: As a result, the width z is calculated for a specified expansion factor as:

With the condition that cos α < 1 for α > 0, the minimum width of the sealing tape on the sheet for a = 0 is produced, i.e. z _min = (Δ - 1) x r. The largest expansion is thus present at the semiminor axis. The roof pitch a thus has no influence on the minimum width of largest expansion.

The width z corresponds in this case to B ₁ or B ₄ , wherein Δ equals the expansion factor. The expansion factor A is in turn calculated at a specified expansion D from the formula: A = 1 + D.

In a particular embodiment of the invention, the sealing tape consists of an expandable backing material and an adhesive. Alternatively, the sealing tape can be formed from an expandable adhesive material and a non-adhesive layer, preferably a film or coating which is applied to the adhesive material. Preferably, the backing material is subjected to creping or microcreping. It preferably has a compression ratio of at least 55%. In an expedient manner, the adhesive or adhesive material is pressure-sensitive and so it can be pressed-on at the sealing point without the adhesive tape layer becoming too thin or perforated. The adhesive is preferably bonded to the backing material. The sealing tape can have a recovery between 4% and 50%. A disadvantage of self-adhesive sealing tapes not based on a backing material subjected to creping in relation to the first and third reference lines is that a certain, generally not precisely specifiable, narrowing of the width is associated with the longitudinal extension. This means that the expanded tape no longer has its original nominal width. This can have the result that the indication of a reference line based on a theoretical nominal width is no longer applicable and becomes imprecise. As a result, backing materials subjected to creping or microcreping are particularly preferred for the self-adhesive sealing tape.

In this respect, reference is made to European patent EP 1 290 289 B1 which describes an expandable sealing material and a method for installing the sealing material on building structures, such as windows and doors, and to European patent EP 1 799 946 B1 which describes a self-adhesive sealing system, and the content thereof is hereby incorporated into this application in relation to the material property of the sealing tape.

In an expedient manner, the backing material includes a nonwoven fabric which is selected from the group consisting of plexifilamentary film-fibril web, spun-bonded polyethylene, spun-bonded polypropylene, spun-bonded polyethylene terephthalate and spun-bonded combinations of polymers selected from the group consisting of polyethylene, polypropylene and polyethylene terephthalate. Alternatively, the backing material can include a film which is selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate and polyamide. Preferably, the backing material is a laminate consisting of a film and a non-woven fabric of the above-mentioned type. The adhesive or adhesive layer is selected from the group consisting of synthetic butyl rubber adhesive, bitumen/rubber adhesive and bitumen/hot melt adhesive. In particular, backing materials which have a material- typical expansion, as is the case for example with specific butyl adhesive tapes, are suitable.

In a particularly preferred embodiment of the invention, the adhesive or the adhesive material includes a synthetic butyl rubber adhesive or polyacrylate adhesive, preferably UV-crosslinked polyacrylate adhesive. In an expedient manner, a pull-off strip (liner), preferably made from silicon paper, is applied to the side of the adhesive or adhesive layer which is open to the outside, in order to protect the adhesive surface from dirt. Covering the adhesive layer with a so-called liner prevents inactivation of the adhesive layer because no dirt, dust or the like can settle on the adhesive or adhesive layer.

Separate protection is claimed for a blank or sealing tape blank which is formed from the just-described self-adhesive, expandable sealing tape. The blank is provided for air-tight sealing of a particularly moisture-variable vapor barrier sheet or dampproof membrane which is already laid or attached to the building and the point designated therefor and which is provided in particular for use in heat insulation of buildings, at a penetration region at which the already laid vapor barrier or dampproof membrane is penetrated by a body or penetration. For this purpose, the sealing tape blank includes a first area which is delimited, in a flanking manner, by the two broad sides produced after cutting, the second reference line and the at least one first reference line, alternatively by the two opposite broad sides, produced after cutting, the second reference line and the third reference line. This first cutting (or blank) area forms a sealing tape tarpaulin which is placed on the synthetic sheet, in particular vapor barrier sheet or dampproof membrane and is adhered thereto when expanded up to a maximum expansion. A second area is also formed by the sheet blank, wherein this is delimited, in a flanking manner, by the two broad sides mentioned above and in addition by the second reference line and the first long side of the sealing tape. This second area is tailored to the circumference of the respective penetrations. When attaching this second area of the sealing tape in its longitudinal direction around the penetration, the sealing tape is, in an expedient manner, not expanded and fixedly adheres to the designated penetration.

In an expedient manner, the second area corresponds to the dimensions, in particular the length corresponds to the circumference of the penetration, wherein in the case of the first and second area a certain overhang of preferably at least 2.5 cm in length remains for an overlapping connection of the sealing tape ends on the end faces. An advantage of this sealing tape is that it is very well suited for installations penetrating through a surface in an inclined manner, which is very frequently the case for pipes or lines in the roof space. In order to transfer the first area of the area blank from the initial state into an optimum long-lasting state (sealing tape fan), the first area of the sheet blank, after being arranged on the synthetic sheet, is pulled over the designated sealing region of the synthetic sheet arranged on the building and is fixedly adhered. In an expedient manner, the first area of the sheet blank is elastically expanded whilst it is pulled over the synthetic sheet. In particular, the expansion occurs in the longitudinal extension direction of the sheet blank from the first sealing tape fastening section to the last sealing tape fastening section.

Separate protection is also claimed for a method for producing an air-tight seal of component penetrations through synthetic sheets in roofs, buildings and the like. The method includes the following steps: a1) cutting a sealing tape to a specific length for producing a sealing tape blank, which length corresponds to the circumference of the penetration and includes an additional length of preferably at least 2.5 cm for an overhang for forming an overlapping joint after attaching the sealing tape to the penetration, or a2) preparing a sealing tape blank, and b) cutting the sealing tape blank along the at least one first reference line, which is preferably formed as a cutting reference line, to a defined width B ₁ or using the third reference line to produce a width B ₄ which is dependent on the circumference of the penetration and on a specified expansion of the sealing tape, thereby producing a second area A ₂ above the second reference line, which area is delimited by a first long side, the second reference line and the two flanking sections of the broad sides of the sealing tape, and wherein a first area A ₁ or A ₄ is defined below the second reference line, which area is delimited by the first reference line or the third reference line, the second reference line and the two flanking sections of the broad sides, c) wrapping the second area A ₂ in its longitudinal direction without expansion around the penetration and adhering same thereto, d) arranging the first area A ₁ or A ₄ on a synthetic sheet provided in the roof or building, expanding it in the longitudinal direction and adhering it to the synthetic sheet.

The invention will be described hereinafter with the aid of an exemplified embodiment which will be explained in more detail with the aid of the following table.

Exemplified embodiment in accordance with the invention

In the following table, optimum widths for the distance B ₁ or B ₄ (mathematical formula symbol: z) are listed for tubular penetrations in a building, in particular a building roof, wherein the expansion factor or D _max , determined according to the above-mentioned measuring method, of 80% with a safety factor S _F of 0.9 (cf. table I and the subsequent calculation of D _B1 ) was used as a basis for the calculation of these widths.

Table II. Width z at expansion factor A = 1 .7 (= D = 70%)

In the first left-hand column, pipe diameters in millimeters are given, namely from 80 mm to 160 mm nominal diameter. The two uppermost rows of Table II. list the values for the angle a of the roof inclination in degrees. These values range from an angle a of 0° to an angle a of 50°, wherein the roof inclination angle a between the slanted roof surface and the horizontal is measured. Table II. is used to calculate the width B ₁ or B ₄ of the sealing tape tarpaulin, at which the outer curved line, i.e. the outer edge of the sealing tape fan has precisely this expansion factor, in fact as a function of the radius of the pipeline, the angle of the roof inclination and the specified, permissible expansion factor of the sealing tape, is determined, according to the previously described method for determining the maximum expansion, of in this case 70% (expansion factor 1 .7). The calculation is performed using the formula provided hereinabove in the description. The expansion depends upon the radius r or circumference U of the pipeline and upon the width B-i or B ₄ of the sealing tape tarpaulin arranged on the synthetic sheet, preferably vapor barrier. Since the expansion at the penetration circumference, i.e. at the radius of the tubular penetration, is equal to zero, because the sealing tape is attached to the pipe without traction, the relative change in expansion is greater the smaller the radius with constant width of the sealing tape tarpaulin. In the sloping, air-tight plane of the synthetic sheet in a steep roof, the penetration opening of the pipeline transitions from circular with radius r into elliptical with a semimajor axis a (= r/ cos α) and a semiminor axis b (= r). The outer curved line of the ellipse with the semiaxes a + z and b + z corresponding to the outer edge or curved line of the sealing plane tarpaulin is calculated via an elliptical integral which is shown hereinabove with the mathematical formula. The angle of α = 0° specifically corresponds to the semiminor axis b = r, whilst the values for α > 0 correspond to the values of the semimajor axis a. It is apparent from the table that the critical value for overexpansion is always at the semiminor axis b (= r), wherein in the case of slight roof inclinations the effect is negligible. The critical value for overexpansion of the sealing tape is the smallest value for a given pipe diameter. Consequently, in order to safely avoid detachment caused by overexpansion the cutting line is to be given as a function of the expansion limit of the values stored in the table in the column for an angle α = 0°.

The invention will be described hereinafter with the aid of exemplified embodiments which will be explained in more detail with the aid of the drawings, in which:

Figure 1 shows a conventional sealing tape, how it is currently used for the air-tight sealing of component penetrations through synthetic sheets;

Figure 2 shows a sealing tape in accordance with the invention in the form of a roll;

Figure 3 shows a sealing tape in accordance with the invention adhered at the sealing point after cutting;

Figure 4 shows a first embodiment of a sealing tape blank in accordance with the invention, with reference lines;

Figure 5 shows a second embodiment of a sealing tape blank in accordance with the invention, with reference lines.

Figure 1 shows a conventional seal by means of adhesive tape 1.1 for a tubular installation penetration in an planar surface region of a building, on which a vapor barrier 3 is arranged. The adhesive tape 1.1 becomes detached from the vapor barrier 3 owing to return forces, built up during mounting, in the region of the planar surface of the adhesive tape (wavy edge). Therefore, the adhesive of the conventional adhesive tape 1.1 shown here is disadvantageously not permanent because the adhesive tape is overexpanded.

With the sealing tape 1 in accordance with the invention and shown in figure 2 in the form of a roll, this disadvantage is overcome, in that reference lines are applied on one side of the sealing tape. This figure shows a first reference line 4 which is used as a cutting reference line. In this first embodiment, the cutting reference line 4 is dashed and is thus visible. The fitter of the sealing tape can cut the sealing tape to a specific width B ₁ along this cutting reference line, said width specifying the expansion D _B1 for a specific circumference of a penetration. A second reference line 5, which is printed in an expedient manner on the backing material of the sealing tape as a dot-dash line, indicates a folding line. A second area A ₂ is defined between a first long side L ₁ and the folding line, said area forming a sealing tape collar 6. A first area A ₁ is defined between the second reference line 5 and the first reference line 4, said area forming the sealing tape plane. After cutting the tape along the cutting reference line 4 to the width - specified for a particular cross-sectional circumference of a penetration - between the first and second reference lines 4 and 5, namely Bi, the sealing tape can be wrapped around the penetration and the second area can be adhered to the penetration, whereupon the first area expands to a recommended expansion D _B1 to form a sealing tape fan and can be adhered to the synthetic sheet 3. The first embodiment in accordance with the invention is advantageous in that owing to the defined width B-i, the sealing tape does not become detached from the synthetic sheet 3. Therefore, permanent attachment of the sealing tape at the penetration point and thus a long-lasting, air-tight seal of the component penetration 2 is possible. Figure 3 shows a mounted sealing blank cutting 9. The dot-dash folding line 5 separates the sealing tape, formed in one piece, into two sections, namely the sealing tape collar 6 and the sealing tape tarpaulin 7. This is optimally adhered to the synthetic sheet 3 in this embodiment without detachment, as shown in figure 1 , being demonstrated along the outer curved line 4 of the sealing tape tarpaulin 7.

Figure 4 shows a sealing tape cutting 9, comprising a rectangular main body having two long sides and having two broad sides. A first long side is designated by L ₁ and a second long side is designated by L ₂ . The overall width of the sealing tape corresponds to a width B ₀ . Two first reference lines 4, 4’, i.e. a first reference line 4 and a second “first” reference line 4’ and a second reference line 5 as a folding line are provided on the surface, shown in figure 4, of the sealing tape which is preferably formed from an expandable backing material and an adhesive attached to the rear side (not visible in the figure). A distance B-i is defined between the folding line 5 and the one first reference line 4. A distance B ₃ is defined between the one first reference line 4 and the second long side L ₂ . A distance B ₄ is defined between the folding line 5 and the second long side L ₂ or the third reference line 8. A further distance is designated by B ₂ between the first long side L ₁ and the folding line 5. In the case of the cutting reference lines 4, 4’, symbols can be provided such as e.g. a pair of scissors or the diameter symbol with corresponding pipe diameter dimensions. For instance, at reference sign 4 a pipe diameter of 7 cm is given by way of example. This information indicates to the user the pipe diameter alongside a cutting line, at which diameter the one first width BT or the second “first” width B _r can be adhered to the synthetic sheet 3 in an expanded manner, without overexpansion occurring after stretching the backing material - subjected to creping in an expedient manner - to form a sealing tape fan. Detachment is thus prevented. In particular, detachment of a first area AT is prevented, which area is delimited by the folding line 5, the cutting reference line 4 and the two broad sides of the sealing tape defined by the distance BT after cutting 9 of the tape between those two broad sides. In this embodiment of figure 4, the second reference line 5 is shown to be visible with a dot- dash line. It is located in the center of the width and may thus be shown in a non- visible manner in an alternative embodiment, not shown here, since the center of the width can be determined as such without a marking. Figure 5 shows a further embodiment of a sealing tape cutting 9 in accordance with the invention. In this further embodiment, the sealing tape collar 6 is formed by the area A2, as previously in figure 4, but the sealing tape tarpaulin 7 is formed with an area A4. The third reference line 8, which corresponds to the second long side L2, with the folding line 5 and the two broad sides defined by the distance B ₄ after cutting 9 of the tape between those two broad sides are the delimitation lines for the area A4. A distance B1 is defined between the second “first” reference line 4’ and the folding line 5. In this case, a further “first” reference line is also provided as a cutting reference line which can be used e.g. for a pipe diameter greater than 7 cm. The precise diameter measurement, not shown here, would be applied on the right next to the diameter symbol of the reference line 4’ if needed.