CH494169A

CH494169A - Plastic bag

Info

Publication number: CH494169A
Application number: CH926868A
Authority: CH
Inventors: Francis Wiehahn Eric
Original assignee: Nasionale Misstowwe Elendoms B
Priority date: 1968-06-21
Filing date: 1968-06-21
Publication date: 1970-07-31

Abstract

Plastic bag which allows trapped gases or steam to escape but prevents moisture entering from outside. Comprises a tube with a sealable open end. The closure seal comprises the open ends of the tube which are folded over about a sealing strip with two flaps on both sides of the bag, forming an inner and two outer closure zones. The inner zone has a space where the two walls of the bag are not interconnected. Pref. the sealing strip is made of a weldable thermoplastic material and the closure zones are welded together.

Description

  

  
 



  Kunststoffbeutel und Verfahren zu seiner Herstellung
Die Erfindung betrifft einen Kunststoffbeutel, welcher die Fähigkeit hat, darin eingeschlossene Gase oder Dämpfe entweichen zu lassen und dabei gleichzeitig die Möglichkeit verhindert, dass Feuchtigkeit von draussen in den Beutel eintritt. Ferner betrifft die Erfindung auch ein Verfahren zur Herstellung eines solchen Beutels.



   Dieser Beutel ist erfindungsgemäss dadurch gekennzeichnet, dass dieser von einem Schlauch gebildet ist, dessen eines offenes Ende mit einem Verschluss versehen ist, welcher von einem um eine Faltlinie gefalteten die offenen Ränder der Beutelwände einschliessenden Verschlussstreifen mit zwei Lappen zu beiden Seiten des Beutels gebildet ist, und dass mit einer entlang des Verschlussstreifens und im Abstand von der Faltlinie angebrachten inneren Verschlusszone die beiden Beutelwände miteinander verbunden und mit zwei äusseren Verschlusszonen die beiden Beutelwände mit den beiden Lappen des Verschlussstreifens verbunden sind, wobei die innere Verschlusszone mindestens eine Unterbrechung aufweist, an welcher die beiden Beutelwände nicht miteinander verbunden sind.



   Durch diese Vorkehrung können im Beutel eingeschlossene Gase oder Dämpfe aus dem Beutel zwischen den Beutelwänden durch die Unterbrechung in der Verbindungszone und weiter quer durch den Zwischenraum zwischen der Faltlinie des Verschlussstreifens und der inneren Verbindungszone durch die freien Enden des Verschlussstreifens nach aussen entweichen. Die Dicke der Beutelwände und die Dimensionen der Unterbrechung in der Verschlusszone bestimmen den Druck, mit welchem die eingeschlossenen Gase oder Dämpfe entweichen.



   In einer vorteilhaften Ausgestaltung des erfindungsgemässen Beutels ist vorgesehen, dass dieser aus einem thermoplastischen Kunststoff und der Verschlussstreifen aus einem schweissbaren Material besteht und dass die Verschlusszonen von Schweissnähten gebildet sind, dass der Abstand zwischen der inneren Schweissnaht und der Faltlinie des Verschlussstreifens relativ klein ist, dass die Unterbrechungen in der inneren Schweissnaht so gross sind, dass Gas und Dampf durch diese entweichen kann, dass die innere Schweissnaht zwei Unterbrechungen im Abstand voneinander nahe den Enden der Schweissnaht aufweist, dass die Unterbrechungen an solchen Stellen angeordnet sind, an welchen die auf die innere Schweissnaht wirkenden Spannungskräfte relativ gering sind, dass die sich an den Unterbrechungen gegenüberliegenden Flächen der Beutelwände mit einer Substanz überzogen sind,

   welche keine Haftfähigkeit zu sich selbst hat, so dass sich die Wände zum Durchlass von Gasen oder Dämpfen leicht öffnen, dass die Substanz eine bei Kunststoffen verwendete Drucktinte ist, dass die sich an den Unterbrechungen gegenüberliegenden Flächen der Beutelwände mit einer Substanz überzogen sind, welche einen bestimmten Grad von Haftfähigkeit zu sich selbst hat, so dass die Wände aneinanderhaften und sich nur dann öffnen, wenn der Druck im Inneren des Beutels einen vorausbestimmten Wert erreicht hat, und dass der Beutel mit einer Schweissnaht nach Art der vorbeschriebenen an beiden Enden versehen ist.



   Das Verfahren zur Herstellung des erfindungsgemässen Kunststoffbeutels ist erfindungsgemäss dadurch gekennzeichnet, dass ein Verschlussstreifen in Längsrichtung über das offene Ende des Schlauches gefaltet wird, wodurch zwei Lappen zu beiden Seiten des Beutels gebildet werden, darauf die beiden Beutelwände miteinander und die Lappen mit den Beutelwänden entlang einer Verschlusszone verbunden werden, wobei die die   Beutelwände    miteinander verbindende innere Verschlusszone mindestens eine Unterbrechung aufweist, an welcher die Beutelwände nicht miteinander verbunden sind.



   In Ausgestaltung des erfindungsgemässen Verfahrens ist vorgesehen, dass der Schlauch aus thermoplastischem Kunststoff und der Verschlussstreifen aus einem schweissbaren Material besteht und dass die Verbindung durch eine Schweissung hergestellt wird, dass die Unterbrechung der inneren Schweissnaht durch ein nicht verbindungsfähiges Material geschaffen wird, wodurch die Verbindung der Wände miteinander an dieser Stelle verhindert wird, wobei das Unterbruchsmaterial mit dem Material des Beutels sogar bei höheren   Temperaturen nicht verbindungsfähig ist und in seiner Lage während des Schweissvorganges   gehalten    wird, dass an der inneren Schweissnaht eine Unterbrechung angebracht wird, indem ein Unterbruchsmaterial zwischen die Beutelwände und den Lappen des Verschlussstreifens angeordnet wird, wobei das Unterbruchsmaterial als Isolation dient und verhindert,

   dass die Innenflächen der Beutelwände miteinander verschweissen, dass das Unterbruchsmaterial aus einem verbindungsfähigen Kunststoff besteht, welcher auf die Beutelwände in geschmolzenem Zustand aufgebracht wird und auf diesen sich verfestigt, dass zwei Unterbrechungen vorgesehen sind, welche im Abstand voneinander und nahe den Enden der inneren Schweissnaht angeordnet sind, und dass die Unterbrechungen an denjenigen Stellen angebracht werden, an welchen die auf die innere Schweissnaht wirkenden Spannungskräfte   reaktiv    klein sind.



   Nachfolgend werden Ausführungsbeispiele des Erfindungsgegenstandes anhand der beiliegenden Zeichnung näher   beschrie"oen.    Es zeigen:
Fig. 1 eine schematische Ansicht des offenen Endes eines Kunststoffbeutels,
Fig. 2 den Beutel mit dem daran angebrachten Verschluss,
Fig. 3 und 4 einen Querschnitt durch den Verschlussstreifen des Beutels entlang der Linie A-A in Fig. 2 vor dem Verschweissen und mit zwei verschiedenen Anwendungen des Unterbruchsmaterials,
Fig. 5 einen Querschnitt durch den Beutel entsprechend den Fig. 3 und 4 jedoch nach dem Verschweissen,
Fig. 6 und 7 Querschnitte durch den Beutel und durch den Verschlussstreifen entlang der Linie B-B in Fig. 2 jedoch vor dem Verschweissen und mit zwei verschiedenen Anwendungen des Unterbruchsmaterials in der glei chen Weise wie in den Fig. 3 und 4 und
Fig.

   8 einen vertikalen Querschnitt durch den Beutel mit Verschlussstreifen entsprechend den Fig. 6 und 7 jedoch nach dem Verschweissen.



   Die Zeichnungen stellen schematisch zwei Arten dar, in welchen ein Verschluss an das offene Ende eines Kunststoffsackes angebracht werden kann.



   Die Beutelwände 12, 14 sind am allgemein mit 10 bezeichneten offenen Ende des Beutels mit Streifen- 16 eines Unterbruchsmaterials versehen. Das Unterbruchsmaterial ist zwischen den Innenflächen der Wände 12 und 14 angebracht und besteht aus einer nicht verbindungsfähigen Drucktinte von der Art, wie sie normalerweise für das Bedrucken von Kunststoffen verwendet wird, beispielsweise die unter dem Handelsnamen bekannte Drucktinte    < eCoate's    Briteflex Flexo  in den
Ausführungen gemäss den Fig.3 und 6. Das Unter bruchsmaterial braucht nur an der Beutelwand 14 ange bracht zu sein. In den Ausführungen gemäss den Fig. 4 und 7 ist das Unterbruchsmaterial an den Aussenflächen der Wände 12 und 14 angebracht und besteht aus einem verbindungsfähigen heiss-schmelzenden Kunststoff.

  In diesem Fall wird das Unterbruchsmaterial auf die Aus senflächen der beiden Wände 12 und 14 aufgebracht. Die
Streifen 16 weisen eine Breite von etwa 7,6 bis   20mm    auf, sind jedoch vorzugsweise 12,6 mm breit und an den
Seiten des Beutels 10 angebracht.



   Ein entlang einer Faltlinie 19 in Längsrichtung gefalteter und aus zwei Lappen 18a und 18b bestehender
Verschlussstreifen 18 ist über die Beutelwände 12 und 14 angeordnet. Eine innere Schweissnaht 20 sowie äussere Schweissnähte 23 sind zwischen den Wänden 12 und 14 und entlang des Verschlussstreifens 18 angebracht. Die Schweissnähte 20 und 23 sind im Abstand von der Faltlinie 19 des Verschlussstreifens 18 angebracht und bilden einen kanalförmigen Raum 22.



   Die Unterbruchsmaterialstreifen 16 verhindern, dass die Wände 12 und 14 an diesen Stellen zusammenschweissen und bilden damit zwei Unterbrechungen 17 in der Schweisslinie 20. Die Unterbrechungen 17 werden in der folgenden Art erzeugt: In den Ausführungsformen gemäss den   Fig. 3    und 6 ist das Unterbruchsmaterial nicht verbindungsfähig mit dem Material des Beutels und verhindert infolgedessen, dass die Wände 12 und 14 an diesen Stellen miteinander verschweissen. In den Ausführungen gemäss den Fig. 4 und 7 ist das Unterbruchsmaterial verbindungsfähig mit dem Material des Beutels und dem Verschlussstreifen und hat demnach zur Folge, dass die Wände 12 und 14 an die Lappen 18a und 18b des Verschlussstreifens anschweissen.

  Es nimmt jedoch genügend Schweisswärme auf, um als Isolierung zu dienen und zu verhindern, dass die Wärme die Innenflächen der Wände 12 und 14 erreicht und diese zusammenschweissen.



   Mit dieser Vorkehrung können die in dem Beutel 10 eingeschlossenen Gase und Dämpfe durch die Unterbrechungen 17 und weiter in Querrichtung durch den kanalförmigen Raum 22 und durch die freien Enden 24 und 26 des Verschlussstreifens 18 nach aussen entweichen. Infolge der kleinen Masse des kanalförmigen Raumes 22 und der Unterbrechungen 17 und infolge der Länge des kanalförmigen Raumes 22 wird verhindert, dass Feuchtigkeit in den Beutel eintritt.



   PATENTANSPRUCH 1
Kunststoffbeutel, dadurch gekennzeichnet, dass dieser von einem Schlauch gebildet ist, dessen eines offenes Ende mit einem Verschluss versehen ist, welcher von einem um eine Faltlinie (19) gefalteten, die offenen Ränder der Beutelwände (12, 14) einschliessenden Verschlussstreifen (18) mit zwei Lappen (18a, 18b) zu beiden Seiten des Beutels gebildet ist, und dass mit einer entlang dem Verschlussstreifen und im Abstand von der Faltlinie angebrachten inneren Verschlusszone die beiden Beutelwände miteinander verbunden und mit zwei äusseren Verschlusszonen (23) die beiden Beutelwände mit den beiden Lappen des Verschlussstreifens verbunden sind, wobei die innere Verschlusszone (20) mindestens eine Unterbrechung (17) aufweist, an welcher die beiden Beutelwände nicht miteinander verbunden sind.

 

   UNTERANSPRÜCHE
1. Kunststoffbeutel nach Patentanspruch I, dadurch gekennzeichnet, dass dieser aus thermoplastischem Kunststoff und der Verschlussstreifen (18) aus einem schweissbaren Material besteht und dass die Verschlusszonen (20, 23) von Schweissnähten gebildet sind.



   2. Kunststoffbeutel nach Patentanspruch I und Un   teranspruch    1, dadurch gekennzeichnet, dass der Abstand zwischen der inneren Schweissnaht (20) und der Faltlinie  (19) des Verschlussstreifens (18) relativ klein ist.



   3. Kunststoffbeutel nach Patentanspruch I und den Unteransprüchen 1 und 2, dadurch gekennzeichnet, dass die Unterbrechungen (17) in der inneren Schweissnaht  (20) so gross sind, dass Gase und Dämpfe durch diese entweichen können. 

**WARNUNG** Ende DESC Feld konnte Anfang CLMS uberlappen**.



   



  
 



  Plastic bags and process for their manufacture
The invention relates to a plastic bag which has the ability to allow gases or vapors trapped therein to escape while at the same time preventing the possibility of moisture from outside entering the bag. The invention also relates to a method for producing such a bag.



   According to the invention, this bag is characterized in that it is formed by a tube, one open end of which is provided with a closure which is formed by a closure strip with two tabs on both sides of the bag, which is folded around a fold line and encloses the open edges of the bag walls, and that with an inner closure zone attached along the closure strip and at a distance from the fold line, the two bag walls are connected to one another and with two outer closure zones the two bag walls are connected to the two flaps of the closure strip, the inner closure zone having at least one interruption at which the both bag walls are not connected to each other.



   This provision allows gases or vapors trapped in the bag to escape outward from the bag between the bag walls through the interruption in the connection zone and further across the space between the fold line of the closure strip and the inner connection zone through the free ends of the closure strip. The thickness of the bag walls and the dimensions of the interruption in the closure zone determine the pressure with which the enclosed gases or vapors escape.



   In an advantageous embodiment of the bag according to the invention it is provided that it consists of a thermoplastic material and the closure strip is made of a weldable material and that the closure zones are formed by weld seams, that the distance between the inner weld seam and the fold line of the closure strip is relatively small, that the interruptions in the inner weld seam are so large that gas and steam can escape through them that the inner weld seam has two interruptions at a distance from one another near the ends of the weld seam, that the interruptions are arranged at those points at which the inner one Tension forces acting on the weld seam are relatively low, so that the surfaces of the bag walls opposite one another at the interruptions are coated with a substance,

   which has no adhesion to itself, so that the walls open easily to allow gases or vapors to pass through, that the substance is a printing ink used in plastics, that the surfaces of the bag walls facing each other at the interruptions are coated with a substance that has a has a certain degree of adhesion to itself, so that the walls stick together and only open when the pressure inside the bag has reached a predetermined value, and that the bag is provided with a weld seam of the type described above at both ends.



   The method for producing the plastic bag according to the invention is characterized according to the invention in that a closure strip is folded in the longitudinal direction over the open end of the hose, whereby two flaps are formed on both sides of the bag, then the two bag walls together and the flaps with the bag walls along one Closure zone are connected, wherein the inner closure zone connecting the bag walls to one another has at least one interruption at which the bag walls are not connected to one another.



   In an embodiment of the method according to the invention it is provided that the hose is made of thermoplastic and the closure strip is made of a weldable material and that the connection is made by a weld, that the interruption of the inner weld seam is created by a non-connectable material, whereby the connection of the Walls with each other at this point is prevented, the interruption material with the material of the bag is not bondable even at higher temperatures and is held in its position during the welding process that an interruption is made on the inner weld seam by placing an interruption material between the bag walls and the tab of the closure strip is placed, the interruption material serving as insulation and preventing

   that the inner surfaces of the bag walls weld together, that the interruption material consists of a bondable plastic, which is applied to the bag walls in a molten state and solidifies on them, that two interruptions are provided, which are arranged at a distance from one another and near the ends of the inner weld seam are, and that the interruptions are made at those points at which the tension forces acting on the inner weld seam are reactively small.



   Exemplary embodiments of the subject matter of the invention are described in more detail below with reference to the accompanying drawings.
1 is a schematic view of the open end of a plastic bag,
Fig. 2 the bag with the attached closure,
3 and 4 show a cross section through the closure strip of the bag along the line A-A in FIG. 2 before welding and with two different applications of the interruption material,
5 shows a cross section through the bag according to FIGS. 3 and 4, but after welding,
6 and 7 are cross-sections through the bag and through the closure strip along the line B-B in FIG. 2, but before the welding and with two different applications of the interruption material in the same manner as in FIGS. 3 and 4 and
Fig.

   8 shows a vertical cross section through the bag with closure strips according to FIGS. 6 and 7, but after welding.



   The drawings schematically illustrate two ways in which a closure can be attached to the open end of a plastic bag.



   The bag walls 12, 14 are provided with strips 16 of an interruption material at the open end of the bag, generally designated 10. The interruption material is applied between the inner surfaces of the walls 12 and 14 and consists of a non-bondable printing ink of the type normally used for printing on plastics, for example the eCoate's Briteflex Flexo printing ink known under the trade name
Versions according to FIGS. 3 and 6. The break material only needs to be attached to the bag wall 14. In the embodiments according to FIGS. 4 and 7, the interruption material is attached to the outer surfaces of the walls 12 and 14 and consists of a bondable, hot-melting plastic.

  In this case, the interruption material is applied to the outer surfaces of the two walls 12 and 14. The
Strips 16 have a width of about 7.6 to 20 mm, but are preferably 12.6 mm wide and at the
Sides of the bag 10 attached.



   One which is folded in the longitudinal direction along a fold line 19 and consists of two flaps 18a and 18b
Closure strip 18 is disposed over bag walls 12 and 14. An inner weld seam 20 and outer weld seams 23 are attached between the walls 12 and 14 and along the closure strip 18. The weld seams 20 and 23 are attached at a distance from the fold line 19 of the closure strip 18 and form a channel-shaped space 22.



   The interruption material strips 16 prevent the walls 12 and 14 from welding together at these points and thus form two interruptions 17 in the weld line 20. The interruptions 17 are produced in the following way: In the embodiments according to FIGS. 3 and 6, the interruption material is not connectable to the material of the bag and consequently prevents the walls 12 and 14 from welding together at these points. In the embodiments according to FIGS. 4 and 7, the interruption material is connectable to the material of the bag and the closure strip and accordingly has the consequence that the walls 12 and 14 weld to the tabs 18a and 18b of the closure strip.

  However, it absorbs enough welding heat to serve as insulation and to prevent the heat from reaching the inner surfaces of the walls 12 and 14 and welding them together.



   With this provision, the gases and vapors trapped in the bag 10 can escape to the outside through the interruptions 17 and further in the transverse direction through the channel-shaped space 22 and through the free ends 24 and 26 of the closure strip 18. As a result of the small mass of the channel-shaped space 22 and the interruptions 17 and as a result of the length of the channel-shaped space 22, moisture is prevented from entering the bag.



   PATENT CLAIM 1
Plastic bag, characterized in that it is formed by a tube, one open end of which is provided with a closure, which is formed by a closure strip (18) which is folded around a fold line (19) and encloses the open edges of the bag walls (12, 14) two flaps (18a, 18b) are formed on both sides of the bag, and that the two bag walls are connected to one another with an inner closing zone attached along the closing strip and at a distance from the fold line and the two bag walls to the two with two outer closing zones (23) Flaps of the closure strip are connected, the inner closure zone (20) having at least one interruption (17) at which the two bag walls are not connected to one another.

 

   SUBCLAIMS
1. Plastic bag according to claim I, characterized in that it consists of thermoplastic material and the closure strip (18) consists of a weldable material and that the closure zones (20, 23) are formed by weld seams.



   2. Plastic bag according to Patent Claim I and Un teran Claim 1, characterized in that the distance between the inner weld seam (20) and the fold line (19) of the closure strip (18) is relatively small.



   3. Plastic bag according to claim I and the dependent claims 1 and 2, characterized in that the interruptions (17) in the inner weld seam (20) are so large that gases and vapors can escape through them.

** WARNING ** End of DESC field could overlap beginning of CLMS **.

Claims

** WARNING ** Beginning of CLMS field could overlap end of DESC **. Temperatures is not connectable and is held in its position during the welding process that an interruption is made on the inner weld seam by placing an interruption material between the bag walls and the tabs of the closure strip, the interruption material serving as insulation and preventing the inner surfaces weld the bag walls together, that the interruption material consists of a bondable plastic which is applied to the bag walls in a molten state and solidifies on them, that two interruptions are provided, which are arranged at a distance from one another and near the ends of the inner weld seam, and that the interruptions are made at those points

at which the tension forces acting on the inner weld seam are reactively small.

Exemplary embodiments of the subject matter of the invention are described in more detail below with reference to the accompanying drawings. 1 is a schematic view of the open end of a plastic bag, Fig. 2 the bag with the attached closure, 3 and 4 show a cross section through the closure strip of the bag along the line A-A in FIG. 2 before welding and with two different applications of the interruption material, 5 shows a cross section through the bag according to FIGS. 3 and 4, but after welding, 6 and 7 are cross-sections through the bag and through the closure strip along the line B-B in FIG. 2, but before the welding and with two different applications of the interruption material in the same manner as in FIGS. 3 and 4 and Fig.

8 shows a vertical cross section through the bag with closure strips according to FIGS. 6 and 7, but after welding.

The drawings schematically illustrate two ways in which a closure can be attached to the open end of a plastic bag.

The bag walls 12, 14 are provided with strips 16 of an interruption material at the open end of the bag, generally designated 10. The interruption material is applied between the inner surfaces of the walls 12 and 14 and consists of a non-bondable printing ink of the type normally used for printing on plastics, for example the eCoate's Briteflex Flexo printing ink known under the trade name Versions according to FIGS. 3 and 6. The break material only needs to be attached to the bag wall 14. In the embodiments according to FIGS. 4 and 7, the interruption material is attached to the outer surfaces of the walls 12 and 14 and consists of a bondable, hot-melting plastic.

In this case, the interruption material is applied to the outer surfaces of the two walls 12 and 14. The Strips 16 have a width of about 7.6 to 20 mm, but are preferably 12.6 mm wide and at the Sides of the bag 10 attached.

One which is folded in the longitudinal direction along a fold line 19 and consists of two flaps 18a and 18b Closure strip 18 is disposed over bag walls 12 and 14. An inner weld seam 20 and outer weld seams 23 are attached between the walls 12 and 14 and along the closure strip 18. The weld seams 20 and 23 are attached at a distance from the fold line 19 of the closure strip 18 and form a channel-shaped space 22.

The interruption material strips 16 prevent the walls 12 and 14 from welding together at these points and thus form two interruptions 17 in the weld line 20. The interruptions 17 are produced in the following way: In the embodiments according to FIGS. 3 and 6, the interruption material is not connectable to the material of the bag and consequently prevents the walls 12 and 14 from welding together at these points. In the embodiments according to FIGS. 4 and 7, the interruption material is connectable to the material of the bag and the closure strip and accordingly has the consequence that the walls 12 and 14 weld to the tabs 18a and 18b of the closure strip.

However, it absorbs enough welding heat to serve as insulation and to prevent the heat from reaching the inner surfaces of the walls 12 and 14 and welding them together.

With this provision, the gases and vapors trapped in the bag 10 can escape to the outside through the interruptions 17 and further in the transverse direction through the channel-shaped space 22 and through the free ends 24 and 26 of the closure strip 18. As a result of the small mass of the channel-shaped space 22 and the interruptions 17 and as a result of the length of the channel-shaped space 22, moisture is prevented from entering the bag.

PATENT CLAIM 1 Plastic bag, characterized in that it is formed by a tube, one open end of which is provided with a closure, which is formed by a closure strip (18) which is folded around a fold line (19) and encloses the open edges of the bag walls (12, 14) two flaps (18a, 18b) are formed on both sides of the bag, and that the two bag walls are connected to one another with an inner closing zone attached along the closing strip and at a distance from the fold line and the two bag walls to the two with two outer closing zones (23) Flaps of the closure strip are connected, the inner closure zone (20) having at least one interruption (17) at which the two bag walls are not connected to one another.

SUBCLAIMS 1. Plastic bag according to claim I, characterized in that it consists of thermoplastic material and the closure strip (18) consists of a weldable material and that the closure zones (20, 23) are formed by weld seams.

2. Plastic bag according to Patent Claim I and Un teran Claim 1, characterized in that the distance between the inner weld seam (20) and the fold line (19) of the closure strip (18) is relatively small.

3. Plastic bag according to claim I and the dependent claims 1 and 2, characterized in that the interruptions (17) in the inner weld seam (20) are so large that gases and vapors can escape through them.

4. Plastic bag according to claim I and the

Dependent claims 1 to 3, characterized in that the inner weld seam (20) has two interruptions (17) at a distance from one another near the ends of the weld seam.

5. Plastic bag according to dependent claim 4, characterized in that the interruptions (17) are arranged at those points at which the tension forces acting on the inner weld seam are relatively low.

6. Plastic bag according to claim I and the dependent claims 1 to 5, characterized in that the surfaces of the bag walls opposite one another at the interruptions (17) are coated with a substance (16) which has no adhesion to itself, so that the Slightly open walls to allow gases or vapors to pass through.

7. Plastic bag according to dependent claim 6, characterized in that the substance is a printing ink used in plastic.

8. Plastic bag according to claim I and the dependent claims 1 to 5, characterized in that the surfaces of the bag walls opposite one another at the interruptions (17) are coated with a substance which has a certain degree of adhesion to itself, so that the walls adhere to each other and only open when the pressure inside the bag reaches a predetermined value.

9. Plastic bag according to claim I or one of the preceding subclaims, characterized in that it is provided with a weld seam at both ends.

PATENT CLAIM II A method for producing a plastic bag according to claim 1, characterized in that a closure strip (18) is folded in the longitudinal direction over the open end of the tube, whereby two Flaps (18a, 18b) are formed on both sides of the bag, then the two bag walls (12, 14) are connected to one another and the tabs (18a, 18b) are connected to the bag walls along a closure zone, the inner closure zone connecting the bag walls to one another at least has an interruption (17) at which the bag walls are not connected to one another.

SUBCLAIMS 10. The method according to claim II, characterized in that the tube made of thermoplastic and the closure strip (18) consists of a weldable material and that the connection is made by welding.

11. The method according to claim II and dependent claim 10, characterized in that the interruption (17) in the inner weld seam (20) is created by a non-connectable material (16), whereby the connection of the walls (12, 14) to each other at this Place is prevented, wherein the interruption material with the material of the bag is not bondable even at higher temperatures and is held in its position during the welding process.

12. The method according to claim II, characterized in that an interruption (17) is made on the inner weld seam (20) by placing an interruption material between the walls (12, 14) of the bag and the tabs (18a and 18b) of the closure strip ( 18), the interruption material (16) serving as insulation and preventing the inner surfaces of the bag walls from welding together.

13. The method according to claim 20, characterized in that the interruption material consists of a bondable plastic which is applied to the walls (12 and 14) of the bag in a molten state and solidifies on the bag walls.

14. The method according to claim II and the dependent claims 11-13, characterized in that two interruptions (17) are attached at a distance from one another and near the ends of the inner weld seam.

15. The method according to dependent claim 16, characterized in that the interruptions (17) are made at those points at which the tension forces acting on the inner weld seam are relatively small.