CN1248949A

CN1248949A - Multicompartment thermoplastic bag

Info

Publication number: CN1248949A
Application number: CN98802881A
Authority: CN
Inventors: 扎因·E·M·萨德; 理查德·道金斯; 迈克尔·J·克路西; 威廉·D·普赖斯
Original assignee: S C JOHNSON STORAGE CORP
Current assignee: S C JOHNSON STORAGE CORP; SC Johnson and Son Inc
Priority date: 1997-01-31
Filing date: 1998-01-09
Publication date: 2000-03-29
Anticipated expiration: 2018-01-09
Also published as: EP0956241B1; KR100445297B1; BR9808893A; WO1998033717A1; EP0956241A1; ATE263070T1; ES2218803T3; CA2279391C; JP2001509118A; AU5911598A; DE69822795T2; KR20000070652A; CA2279391A1; AU730377B2; CN1071243C; NZ337005A; DE69822795D1

Abstract

A multicompartment reclosable thermoplastic bag (10) having at least two compartments (15, 16) is disclosed. Each compartment has a top, a bottom, side edges, and two opposing sidewalls joined at the side edges and the bottom. Each compartment has a closure (31, 32) across the top thereof, which are arranged back-to-back and aligned such that the center points of each closure are less than 1/2 inch (1.27 cm) away from each other. The compartments are attached together proximate the tops of the compartments, and the bottoms of the compartments are free from being attached to each other. A process for making the bag is also disclosed.

Description

The multicompartment thermoplastic bag

The present invention relates to reclosable thermoplastic bag.More particularly, the present invention relates to have the thermoplastic bag of the reclosable of many compartments.

The reclosable thermoplastic wraps in the packaging for foodstuff and often uses.Bag is usually made by a kind of plastic sheeting and is had at the bottom folding with at two sidewalls of side sealing-in.Wrap in its top and generally have a reclosable fastener, for example a kind of adhesive agent, a kind of toe-in, or a plastic fastener of in the US Patent 5,140,727 of authorizing people such as Dais, describing.

Use the user of these bags to need not only bag through the specified time of being everlasting.Therefore, developed the bag that has more than a compartment.For example, US Patent 4,993,844 disclose a kind of locellus bag.But in patent 4,993, the closure member of bag moves relative to each other in 844, makes the user be difficult to close a compartment and need not push article in another compartment.In addition, above-mentioned patent has been described a common wall that is used for compartment, has limited the available volume in the compartment.Another example is a US Patent 5,024,536, has described a bag that compartment is arranged of sealing-in again.But this patent has been described the compartment of bag and has been sealed along the compartment base, thereby has limited available volume in the compartment.

It is a kind of improvement that a kind of many compartments Bao Ze is provided in the field of locellus bag, and wherein all compartments can be closed simultaneously but be opened independently of one another, and available volume maximum in the compartment wherein.

The invention provides a kind of like this thermoplastic containers with reclosable of many compartments.In one aspect, the present invention is a kind of many compartments reclosable thermoplastic bag, comprise: at least two compartments, each compartment has a top, a base, two opposed side edges and at two relative sidewalls of side and base bonded assembly, each compartment has a closure member that crosses its top, closure member is arranged to dos-, the closure member alignment, the center-point each interval of each closure member is less than 1/2 inch (1.27cm), it is characterized in that compartment connects together near the compartment top, cell bottom does not link to each other each other.

In a second aspect, the invention provides a kind of method of processing a kind of thermoplastic bag of the reclosable with many compartments, the step of the method comprises: with the folding form one thin web is converted at least four a, b, c and d, these piece series connection make piece a adjacent with piece b, piece b is adjacent with piece c, and piece c is adjacent with piece d; One closure member is set on each piece, makes all closure member alignment; And the side of four pieces of sealing-in is to form a bag with at least two compartments, and closure member forms a closed area so that the compartment and the external world are separated like this.

Many compartments bag of the present invention has advantage, because all compartments can be closed simultaneously, opens but each compartment can be independent of other compartment.If desired, the available volume in many compartments of the present invention bag compartment can increase, because compartment is not connected with each other along the bottom.Another advantage of the present invention is that many compartments bag can be made with a monoblock thermoplastic film.

Fig. 1 is a block diagram of multicompartment thermoplastic bag of the present invention;

Fig. 2 is a cutaway view of Fig. 1 bag;

Fig. 3 is the cutaway view that is used for a closure member of Fig. 1 bag;

Fig. 4 is a planar view that is used to process a stripper plate of the many compartments of the present invention;

Fig. 5 is a cutaway view of the plate of Fig. 4.

Fig. 1 shows the Reclosable of compartment more than thermoplastic bag 10 of the present invention.Bag 10 comprises at least two compartments 15 and 16.Each

compartment

15 and 16 has a top, a bottom, side and two relative sidewalls that link to each other with the bottom at side.Like this, compartment 15 has a base 17 and two opposed side edges.Compartment 16 equally also has a base 18 and two opposed side edges.Each compartment also has the closing member that crosses its top.Like this, compartment 15 has the closure 31 that passes its top, and compartment 16 has the closure 32 that crosses its top.Bag 10 also comprises

compartment

15 and 16 is connected near its top device.

Compartment 15 and each sidewall of 16 are made by one deck thermoplastic film.Bag 10 comprises four-

level membrane

11,12,13 and 14 at least like this.Each

layer

11,12,13 and 14 has a top margin, a base and two opposed side edges.Layer 11 is connected to form compartment 15 with side along the base with 12.Layer 13 is connected to form compartment 16 with side along the base with 14.Like this, as shown in the figure, layer 11 is skins of first compartment, and layer 12 is internal layers of first compartment.Equally, layer 14 is skins of second compartment, and layer 13 is internal layers of second compartment.

Fig. 2 illustrates the cutaway view of an embodiment of bag of the

present invention.Layer

11,12,13,14 can by any suitable thermoplastic film for example low density polyethylene (LDPE), Linear low-density polyethylene, be the ethene of linearity and C3-C8 alpha olefin copolymer, polypropylene, Vingon, ethane-acetic acid ethyenyl ester, poly(lactic acid), two or more these mixture of polymers substantially, perhaps a kind of such poly-mer and another kind of thermoplastic polymer's compound.If desired, film can be a kind of co-extrusion film.

The base 17 of compartment 15 and the base 18 of compartment 16 can use any required method to form.For example, the base can pass through folding film, by heat-sealing, by ultrasonic sealing, adhesive seal or by any other required method formation.

Compartment

15 and 16 side form by using any required method along the thin layer side thin layer to be linked together.For example, side can be sealed by hot line, hot knife sealing, ultrasonic sealing, adhesive seal or form by any other required method.The result is that per two thin layers connect together and make two layers form a compartment together.Like this, in Fig. 1 and 2,

layer

11 and 12 is joined together to form compartment 15, and

layer

13 and 14 is joined together to form compartment 16.All layers can connect together along side if desired.

Bag 10 comprises compartment 15 and compartment 16 is connected near the top of compartment device that wrapping 10 like this is exactly an

integral unit.Compartment

15 and 16 can be connected near the top in any required mode.For example, compartment can be connected by heat-sealing or ultrasonic encapsulation continuous or that be interrupted.

Perhaps, as shown in Figure 3, compartment can connected between

layer

12 and 13 by the folding line 52 in the film.Folding line 52 can on the fastener or under.In a preferred embodiment, folding line 52 extends about 0.5 inch on the bottom of fastener.

Perhaps, with

compartment

15 and 16 bonded assembly devices can be between

layer

12 and 13 continuously or be interrupted the adhesive agent 36 that is provided with.Adhesive agent preferably is applied near the point of closure member.Suitable adhesive agent comprises anyly provides sufficient viscosity that the layer while compartment 15 and/or 16 that keeps linking to each other opened to thin layer 12 and 13.This adhesive agent comprises HM2707 and HL2203, and is available from H.B.Fuller.When closure member along two

layers

12 and 13 all be provided with so that closure member is stable and during alignment adhesive agent just particularly useful.

Compartment can connect with any other suitable mode, for example by a kind of poly-mer of extruding such as low density polyethylene (LDPE).Near the effect that compartment is connected the top is the closure member mobile minimum each other that makes alignment.When moving hour of closure member, client is easy to close compartment simultaneously and open one or more compartments.

As shown in Figure 3, in a preferred embodiment, used a folding line 52 and an adhesive agent 36 simultaneously as the device that is connected compartment.In this embodiment, adhesive agent 36 from folding line point 52 be applied to downwards at least between profile 31b and the 32b a bit on.This spacing can be as high as 0.5 inch (12.7mm), but preferably adhesive agent be applied to a width from about 1/8 inch (3.17mm) to the band of about 1/6 inch (1.59mm).Preferably adhesive agent is applied between profile 31b, the 32b or on profile 31b, the 32b.

Bag 10 comprises a closure member that is provided with along the top of each compartment, and each

compartment

15 and 16 all has the complete closure member that crosses the top like this.Term " closing member " limits a part that refers to a closure member here.For example, on a slide fastener closure member, a closing member is or another profile of slide fastener, for example a flange profile or a groove profile.In an adhesive agent closure member, a closing member is one or another adhesive strip.Closing member can secondary applies, whole in or be laminated on the film, all these is that closure member is applied to the generally well-known method that the thermoplastic of Reclosable is wrapped.

In one embodiment, a bilateral zipper strip can be laminated to the top of layer 12 and 13.All has a plastic fastener profile on the zipper strip both sides of one bilateral zipper strip, i.e. a flange profile or a groove profile.Profile is stretched from each epitaxial lateral overgrowth of zipper strip and is made a single zipper strip comprise two profiles of from then on extending.

Fig. 3 illustrates a cutaway view that can be used for closure member 31 of the present invention and 32.Closure member 31 and 32 can be any suitable closure member.For example, as shown in the figure, closure member 31 can be the plastic fastener with interlockable profile 31a and 31b, and closure member 32 also can be the plastic fastener with interlockable profile 32a and 32b.But closure member can be bonding closure member or any suitable Reclosable closure member if desired.

The profile 31a of plastic fastener, 31b, 32a and/or 32b are provided with along the top of

layer

11,12,13 and 14, and each compartment has a complete closure member along its top like this.Although the closure member on any two compartments can be identical, not needing must be identical.For example, compartment can have a plastic fastener and another compartment can have an adhesive agent closure member.

Closure member on each compartment is in alignment with each other substantially, can close with a motion all compartments of a user like this.In this way, all compartments can be closed simultaneously.Term " alignment " is arranged in a row at the center-point that this is meant profile, can only see a closure member like this from a front side figure, thereby and other all closure member is arranged in a row and blocks closure member and being blocked substantially substantially.Preferably the closure member alignment makes center-point be less than or equal to 1/2 inch (1.27cm) each other apart.Be more preferably, center-point is each other at a distance of 1/4 inch (0.63cm), and optimal cases is that center-point is each other at a distance of 1/8 inch (0.32cm).

As Figure 1-3, closure member is positioned to flange profile 31b and 32b is in alignment with each other.In the embodiment shown, the flange profile is positioned to dos-.Term " dos-" is meant that at this closure member basic fixed position becomes adjacent one another are but separates each other.In an illustrated embodiment, it is adjacent with closure member 32b that closure member 31b is positioned at, and closure member 31b and 32b be positioned to closure member each other back to.Like this, just dos-alignment as described of closure member 31b and 32b.

Dos-alignment makes the user can make two closure members 31 and 32 interlockings on two

compartments

15 and 16 like a cork in single motion.On the other hand, closure member 31 and 32 can be opened independently of one another, and such compartment can be opened and another compartment keeps closing.

In one embodiment, bag can be designed to a closure member and can preferentially open.In other words, plastic fastener crosses its top when being provided with when being surrounded by two adjacent compartments, and the power that need open a plastic fastener is adjusted to the power of opening another plastic fastener greater than needs.Can use any required mode to adjust crack force.For example, the crack force of a plastic fastener can be adjusted by changing the profile geometric configuration.Example comprises that the groove that makes a groove profile is big or make the flange of a flange profile thinner, or changes one or more radiuses that each has contact with in the closure member.Perhaps, can become to have the crack force that the differentiated friction characteristic is adjusted plastic fastener by the type change that changes plastics.

Compartment can be that size equates, but they are not must be so.Preferably compartment all has equal widths, but the width of compartment can change.For example, all compartments can have the width of one 6.5 inches (16.51cm) and the thickness of one 8 inches (20.32cm).Perhaps, all compartments can have the width of one 6.5 inches (16.51cm), and another compartment has the thickness of one 6 inches (15.24cm) and compartment has the thickness of one 8 inches (20.32cm).

The thickness of thin layer can equate or thickness can change.For example, if desired, all

layers

11,12,13 and 14 can have in 2.5 mils (0.0635mm) to the thickness between 5.0 mils (0.127mm), and this is-typical thickness of the freezing bag of ZIPLOC board.Perhaps, layer can all have at the thickness of 1.75 mils (0.0445mm) to 2.7 mils (0.0686mm) scope, this is the typical thickness that the ZIPLOC board is stored bag, perhaps

layer

11,12,13 and 14 can have in 1.0 mils (0.0254mm) to 1.2 mils (0.0305mm), and this is the typical thickness of a ZIPLOC board sandwich or fast food bag.On the other hand,

layer

11,12,13 and 14 different-thickness that can have above thickness combination in any.And one or

more layer

11,12,13 and/or 14 can be thinner, from 0.6 mil (0.0152mm) to 1.2 mils (0.0305mm).The desired thickness of each layer depends on the final use of many compartments bag.For example, thicker thin layer is useful to longer storage usually, and thin film thickness is useful to the article that are used for short-term and deposit.The layer that thin layer is also thicker is attached on the material of packing easily.

If desired, one or more layer can micropunch.Term " micropunch " means be installed with aperture in film.A kind of like this micropunch film makes compartment be suitable for depositing therein article, because the micropunch film can be breathed freely article.Preferably micropunch or aperture have 200 microns sizes to about 900 micrometer ranges.If desired, different layers can have different micropunch figures therein.For example, layer 12 micropunch that can have in 200 to 300 micrometer ranges, and layer 13 can have 800 to 900 microns micropunch.Preferably the density of micropunch is that every layer film is 100 to 500 micropunch, and thin layer is 6.625 inches (16.83cm) * 7 inch (17.78cm).Micropunch can be on a layer rectangular distribution, can be one group perhaps with several micropunch.In addition, different thin layers can have different micropunch figures.Usually, can use the combination of any micropunch figure.Micropunch can use any conventional approach such as hot revulseur to form.The more detailed situation of relevant micropunch bag is in US Patent 5,492, describe in 705, at this as reference.

If desired, one or more layers can impress.Be stamped in film surface and form a kind of pattern.So impression provides a visual cues that thin layer is different with other thin layer to the user, because pattern differently disperses light, thus the profile of change film.And, be printed on the easier food that is adjacent to storage of the surface ratio smooth surface of pattern.Any layer combination can impress.

The best practice of making bag of the present invention is since a pressing steps well known in the art.Bag is made by a bulk of thermoplastic film stripper plate.Fig. 4 illustrates a kind of example of stripper plate 40, can be used for making bag of the present invention.Plate 40 comprises at least four 41,42,43 and 44, each piece shows as a thin layer of final bag.Like this, piece 41,42,43 and 44 is equivalent to the

layer

11,12,13 and 14 of bag shown in Fig. 1 to 2.Piece 41,42,43 and 44 can be identical size, and perhaps the size of piece can change according to the required size of final compartment.

As shown in the figure, stripper plate 40 comprises with it and is the profile 31a of one, 31b, 32a and 32b.But if desired, profile 31a, 31 b, 32a and 32b can after add that promptly after-applied in film extrusion, perhaps profile 31a, 31b, 32a and 32b can be by linking on the plate to its lamination one zipper strip.In one embodiment, a bilateral zipper strip has profile 31b and have profile 32b on its opposite side on the one side, and this bilateral zipper strip can be laminated on the plate.When profile and plate 40 are monolithic extruded, preferably profile 31b and 32b on plate 40 side by side, like this when plate 40 folds, profile 31b as described below and 32b dos-.

If desired, any or all piece 41,42,43 or 44 can micropunch or impression.Like this, the some or all of layers of finished product bag are with micropunch or impression.And if the finished product bag will have the layer of different-thickness, the extrusion dies outlet can be designed to the die clearance difference, thereby forms the stripper plate 40 with many thickness.When plate 40 folds, as described below, layer will have different thickness.

Fig. 5 shows the mode that plate 40 can folding forms bag of the present invention.Plate 40 can 51,52 and 53 foldings along the line.Folding will form

base

17 and 18 along broken line 51 and 53 respectively.

Along the line 52 folding will make profile 31b and 32b be positioned to dos-.Broken line 52 still is the position that compartment 15 links to each other with 16.Along the line 51 and 53 folding can make profile 31a and 32a align to close compartment with profile 31b and 32b.Best, near stripper plate attenuation broken line 52 is called " thin district " at this.Thin district makes folding easier.Be more preferably, thin district is less than or equal to half of stripper plate remainder thickness.Even more preferably, thin district is thick be 0.5 mil (0.0127mm) to 2.0 mils (0.0508mm) and preferably thick be that 1.0 mils (0.0254mm) are to 1.5 mils (0.0381mm).If thin district is too thin, plate can be easy to tear.Preferably thin district is that 1/4 inch (6.35mm) left and right sides is wide.

If desired, when stripper plate 40 foldings, adhesive agent can be arranged on the either side of broken line 52 along the back side of plate.Like this, when plate 40 foldings, compartment connects by folding lines and along the adhesive agent that plate is provided with.Adhesive agent can align the slide fastener profile better, puts in place and can not relatively move each other because profile 31b and 32b will be fixed.Usually, compartment is also connected by side seal.

At the plate folding and after applying adhesive agent, plate is along the limit heat sealing of bag.Heat sealing sees through all pieces or the layer of bag.Heat sealing can use hot water radiation wire, heat-sealing pincers or any other required mode to finish.Like this, just formed the side of compartment.

If desired, plate can carry out Corona discharge Treatment before folding.Corona discharge Treatment can easily be printed on the bag surface.For example, can be printed on a striped along the bottom of one or more compartments, so that the user can see the position of cell bottom.

Following example is not in order to limit scope of the present invention.Example 1

A kind of many compartments bag with two compartments is provided.First compartment has the size of long 6.625 inches (16.83cm) * wide 7 inches (17.78cm).Second compartment has the size of long 4.75 inches (12.06cm) * wide 7 inches (17.78cm).

The mean thickness of two sidewalls of first compartment all is 1.1 mils (0.028mm).The mean thickness of two sidewalls of second compartment all is 1.1 mils (0.028mm).One groove profile of one plastic fastener is along the skin setting of first compartment, and skin is formed by the monolithic extruded technology of model.Equally, a groove profile of a plastic fastener is along the skin setting of second compartment, and skin is formed by the monolithic extruded technology of model.The flange profile is along the either side dos-alignment of a bilateral zipper strip, and zipper strip is laminated on the internal layer top of first compartment.

Two compartments connect in succession by the broken line in the film of two interior interlayers and by the side seal along the side that wraps.Broken line is positioned at 0.5 inch (1.27cm) under the plastic fastener approximately when slide fastener is closed.The bilateral zipper strip of lamination extends upward so that the flange profile on each side of zipper strip can contact with the groove profile and interlocking from broken line, thereby closes compartment.Example 2

A kind of many compartments bag with two compartments is provided.First compartment has the size of long 6.625 inches (16.83cm) * wide 7 inches (17.78cm).Second compartment has the size of 4.75 inches of length * wide 7 inches (17.78cm).

The mean thickness of two sidewalls of first compartment is 1.1 mils (0.028mm).The mean thickness of two sidewalls of second compartment is 1.1 mils (0.028mm).One plastic fastener all is provided with along the top of first and second compartments.

Two compartments connect by the broken line in the film between two internal layers and by being located at two adhesive agents between the internal layer.In addition, compartment is connect along the side of bag by side seal and connects.Example 3

A kind of many compartments bag with three compartments is provided.First compartment has the size of long 8.5 inches (21.59cm) * wide 7 inches (17.78cm).Second compartment is long 6.625 inches (16.83cm) * wide 7 inches (17.78cm).The 3rd compartment is long 4.75 inches (12.06cm) * wide 7 inches (17.78cm).

The mean thickness of two sidewalls of first compartment is 2.2 mils (0.056mm).The mean thickness of two sidewalls of second compartment is 1.1 mils (0.028mm).The mean thickness of two sidewalls of the 3rd compartment is 1.1 mils (0.028mm).

One plastic fastener all is provided with along the first and second compartment tops.One adhesive agent closure member is provided with along the 3rd compartment top.

Compartment is connected by broken line in the film between the adjacent layer and the adhesive agent that is located between the adjacent layer.In addition, compartment is connect along the side of bag by side seal and connects.Example 4

Two compartments connect by the broken line in the film between two internal layers and by being located at two adhesive agents between the internal layer.In addition, compartment is connect along the side of bag by side seal and connects.

Skin corresponding to layer 11 first compartment of Fig. 1 is carried out micropunch.The mean diameter of aperture is 250 microns.500 apertures are arranged on layer.

Skin corresponding to layer 14 second compartment of Fig. 1 is carried out micropunch.The mean diameter of aperture is 850 microns.100 apertures are arranged on layer.Example 5

A kind of many compartments bag with two compartments is provided.First compartment has the size of long 6.625 inches (16.83cm) * wide 7 inches (17.78cm).Second compartment also has the size of long 6.62 inches (16.83cm) * wide 7 inches (17.78cm).

Thickness average out to 3.5 mils (0.089mm) of the lateral wall of first compartment.Thickness average out to 0.8 mil (0.020mm) of the madial wall of first compartment.Equally, thickness average out to 3.5 mils (0.089mm) of the lateral wall of second compartment, and thickness average out to 0.8 mil (0.020mm) of the madial wall of second compartment.Top along first and second compartments is equipped with a plastic fastener.

Two compartments connect by the broken line in the film between two internal layers and by an adhesive agent that is located between two internal layers.In addition, compartment is connect along the side of bag by side seal and connects.

The internal layer of first and second compartments all passes through impression.The diamond shape of pattern on the embossed layer for repeating.

Although show some representational embodiment and details for example purpose of the present invention, but can carry out many changes to method and apparatus disclosed herein without departing from the scope of the invention to those of ordinary skills obviously, scope of the present invention limits in claims.

Claims

1. the thermoplastic of compartment reclosable more than kind bag comprises:

At least two compartments, each compartment has a top, a base, two opposed side edges and at two relative sidewalls of side and base bonded assembly, each compartment has a closure member that crosses its top, closure member is arranged to dos-, the closure member alignment, the center-point each interval of each closure member is less than 1/2 inch (1.27cm)

It is characterized in that compartment connects together near the compartment top, and the base of compartment does not link to each other each other.

2. bag as claimed in claim 1 is characterized in that, compartment is connected together near the top by folding district, an adhesive agent, a heat sealing, a ultrasonic seal, an extruded lamination or a kind of its array mode of a plastic films.

3. bag as claimed in claim 1 is characterized in that, the closure member at least one compartment is a plastic fastener.

4. bag as claimed in claim 1 is characterized in that, the closure member at least one compartment is an adhesive agent closure member.

5. bag as claimed in claim 1 is characterized in that, the closure member at least two adjacent compartments is a plastic fastener.

6. bag as claimed in claim 5 is characterized in that the crack force of a plastic fastener is greater than the crack force of another plastic fastener.

7. bag as claimed in claim 5 is characterized in that, two profiles of plastic fastener are the dos-alignment on a bilateral zipper strip.

8. bag as claimed in claim 1 is characterized in that the size of compartment changes.

9. bag as claimed in claim 1 is characterized in that the thickness of sidewall changes.

10. bag as claimed in claim 1 is characterized in that, at least one sidewall of a compartment has aperture.

11. the method for the thermoplastic bag of an a kind of reclosable with a plurality of compartments of processing, the step of the method comprises:

With the folding form one thin web is converted at least four a, b, c and d, these piece series connection make piece a adjacent with piece b, and piece b is adjacent with piece c, and piece c is adjacent with piece d;

One closure member is set on each piece, makes all closure member alignment; And

The side of four pieces of sealing-in is to form a bag with at least two compartments, and closure member forms a closed area so that the compartment and the external world are separated like this.

12. method as claimed in claim 11 is characterized in that, by closure member and thin web being become one push closure member, closure member being arranged on the thin web or to thin web lamination one zipper strip closure member is located on described later.

13. method as claimed in claim 11 is characterized in that, the sealing-in by a hot water radiation wire sealing-in, the sealing-in of heat sealing pincers, a ultrasonic seal or an adhesive agent sealing-in of the side of four pieces.

14. method as claimed in claim 11 is characterized in that, described measure-alike.

15. method as claimed in claim 11 is characterized in that, described change in size.

16. method as claimed in claim 11 is characterized in that, stripper plate variation in thickness, a described like this variation in thickness.

17. method as claimed in claim 11 is characterized in that, stripper plate comprises a plate thin district of folding therein.