CN103193023A

CN103193023A - Film bag

Info

Publication number: CN103193023A
Application number: CN2012105924897A
Authority: CN
Inventors: A·德维斯; W·提尔兹
Original assignee: Rudolf Wild GmbH and Co KG
Current assignee: Adm Wilder Europe Ltd
Priority date: 2012-01-04
Filing date: 2012-12-31
Publication date: 2013-07-10
Anticipated expiration: 2032-12-31
Also published as: JP5783638B2; EP2612826A1; JP2013139297A; CN103193023B; US20130170772A1

Abstract

The disclosure relates to a multilayer film bag (1) for storing food products, in particular beverage concentrates, with a bag wall (7) including at least one external wall (10), one barrier layer (9), for example for oxygen and/or light, and one internal wall (8). The multilayer film bag includes a predetermined breaking point (2) in the film bag wall which tears open under pressure, for example at pressures above 100 kPa, 150 kPa, 200 kPa, 400 kPa or 500 kPa without any parts of the film bag tearing off.

Description

Bag film

Technical field

The present invention relates to the bag film for stored prod, particularly food, as (bubble-tight or the be rich in CO2's) beverage concentrate that mixes with water, as soft drink.The present invention also further relates to the method for emptying bag film.

Background technology

Laminated film bag has been well-known, for example, has described in EP0473517 under the effect of laser, and bag film uses and divests type (tear-off) seam, and like this, the user can open it more like a cork.But, describe among the EP0473517 to open bag film by machine be pretty troublesome.

In the USD642068S file, product put into container after, by thermal process one oxygen impermeable paper tinsel is welded on the container.But container itself does not comprise any anti-oxygen film.The production of container, can and sealing need a plurality of processing steps, and be therefore complicated and expensive.The viscosity of product is only limited to liquid and free-pouring product, because they can be rushed out or extrude container at an easy rate.For this situation, needed complex appts is product mix subsequently, for example, water is mixed in the beverage.Like this when product flow through container do not have the sterilization the edge time, also just increased the pollution of bacterium.

Summary of the invention

Therefore, a bag film, a method and an equipment have been the purpose of this invention is to provide, like this, it just can stay any residue ground emptying amorphous thin film bag hardly, and wherein, bag film also comprises the barrier of light and/or oxygen, and is that microbial safety is handled.

The equipment of the method for the laminated film bag of claim 1, claim 11 and claim 16 can be realized according to the present invention.Advantageous embodiments and further the improvement are the themes of dependent claims.

According to the laminated film bag with bag layer (bag wall) of the present invention, wherein the bag layer comprises at least one skin, a barrier layer, for example blocking oxygen and/or light, and internal layer, described internal layer comprises the reduction (weakening) in the bag film layer, it is under the effect of pressure, can be used as predetermined breaking in a controlled manner tears, for example surpass 100kPa, 150kPa, 200kPa, 400kPa or 500kPa at pressure, namely, particularly for example, in technological process without any the isolation of components of bag film.

The benefit of doing like this is, no matter the shape of bag film how, can be at an easy rate and machinery turned letter and almost do not stay any residue safely, and not have the bag film component affects of separation and optionally follow-up method and product treatment step are caused microbial contamination.

Reduction as predetermined breaking, it advantageously is attached on the skin of bag film between two parties, and for example, under the effect of light, make, advantageously, described reduction can have a prolongation, its less than the prolongation on the outer layer side of predetermined breaking place half, 1/3rd or 1/4th.Can promote the mechanical emptying of bag film under pressure in the position of the predetermined breaking at the outer center of bag film, therefore can guarantee better, for example, described reduction or predetermined breaking lay respectively at the top of the egress hole of emptying chamber, no matter bag film rotation in one plane.But the non-central location of the predetermined breaking on the bag film skin also can be imagined and obtains.

Advantageously, bag film can have the shape of rectangle and comprise at least one weld seam, and it is used for being filled the rear enclosed bag film at bag film, and weld seam/many weld seam opposings are higher than the pressure of above-mentioned range of pressure, cause an opening of predetermined breaking.

In addition, predetermined breaking can comprise a lid, and for example a protective film prevents pollutants and stain by adhesive, and the tongue of a lid, and it is used for manually or mechanically removing lid before emptying.

In addition, the degree of depth of the predetermined breaking in the bag film skin does not arrive darker than barrier layer, and this is favourable.This is conducive to guarantee to be stored in the influence that product in the bag film is not subjected to light or oxygen, and before opening, light or oxygen can penetrate into the zone of predetermined breaking.

Preferably, bag film has the height dimension less than length and width dimensions.

Similarly, bag film can provide a position detection marks.This helps in pumping equipment, the verification of bag film tram and direction.

Advantageously, under the effect of pressure, predetermined breaking can outwards be protruded and form a convex shape (outward shape) before being torn/tearing.Then, after bag film was torn under pressure easily, it can be more easily and almost entirely is drained and does not stay any residue.

In addition, in evacuation procedure, to protrude may be favourable owing to predetermined breaking for bag layer, and like this, after the emptying, predetermined breaking is sealed in antidrip mode.

According to the present invention, store viscosity in the bag film greater than the liquid of 100mPa, can be therefore emptying and do not stay any residue basically.

In the further advantageous embodiments of the present invention, what can expect is, a small amount of gas, bubble for example, be located at the sidewall in the container that lies low, this sidewall is positioned at top and the opposite of predetermined breaking, and when bag film was drained, it can wash the egress hole of the predetermined breaking of any product.

According to the present invention, the emptying bag film can be realized by the method for following pumping equipment.

In this course, bag film is placed in the emptying chamber, preferably its physical dimension can be adjusted, width and height according to bag film, adjust width and the length of emptying chamber, and by pressure device, for example be reduced on the bag film by pressure device, apply pressure on the bag film, like this, form and protrude, when the bag film layer over expansion of bag film predetermined breaking one side, then open predetermined breaking, for example, the heart therein, and bag film is drained, and does not almost stay any residue.

In addition, when exerting pressure, by the compressible mat on the pressure device, can cross the surface dispersive pressure equably of bag film.

Advantageously, when pressure device reduced, the mat of pressure device may be expanded in the protrusion of bag film layer, because there is not the formation of resistance in the egress hole zone of emptying chamber, and the product that stores in the bag film almost completely can be extruded.

When described bag film is drained by the bubble in the bag film, described bubble be positioned at drain position place bag high go up point most, also the product resistates may be gone out bag film.

And, after bag film is drained, bag film is discharged in the product chambers/on, and flushing product chambers, it is possible for example using commingled water (bubble-tight or be mixed with CO2's).

Description of drawings

Mode with embodiment shows accompanying drawing:

Fig. 1 a is the 3-D view of a bag film exemplary design;

Fig. 1 b is the birds-eye view of Fig. 1 bag film;

Fig. 1 c is the section drawing that runs through the bag film layer;

Fig. 1 d is the birds-eye view of difform predetermined breaking;

Fig. 2 is the 3-D view of a lid;

Fig. 3 a is the emptier part lateral plan with an insertion bag film;

Fig. 3 b is the section drawing of a step snapshot in the process of emptying bag film;

Fig. 3 c is the section drawing of rinsing step snapshot;

Fig. 4 is the 3-D view of the bag film of emptying;

Fig. 5 is the side-looking exploded drawings of pumping equipment part.

The specific embodiment

Fig. 1 a has shown the 3-D view of laminated film bag 1 embodiment, and it has a predetermined breaking of making under the effect of light.Here, the height 3a of bag film 1 is littler than its length 3b and width 3c.

Fig. 1 b has shown the view of bag film in the mode of embodiment, and predetermined breaking is positioned at a side of Fig. 1 bag film.For example, predetermined breaking is positioned at the bottom 6 of bag film.

In this example, the length 3b of container has the identical length of side with width 3c, and still, the geometric configuration of bag film 1 also can be designed to another kind of shape, as rectangle, polygon or circle.Can advantageously be located on the diagonal line 4 and/or advantageously on the center 5 at bag film 1 in the weakened locations of the predetermined breaking 2 on the bottom 6 of container 1.But, also can imagine the weakened locations of other predetermined breaking 2, neither at the center also not on diagonal line.With respect to the plane of inserting, no matter its rotation can correctly be placed on container 1 in the emptying chamber 24, bag film 1 can provide a position detection marks 2a to serve as a mark in order to ensure operator/machine.For example, this position detection marks can be designed to the cut in the bag layer, as hole, picture, trace, paster etc.

Fig. 1 c has shown the partial view that runs through laminated film bag layer 7.The inner wall layer 8 of bag film layer can advantageously be made up of thermoplastic plastic, for example PE, PP, PET, PA or other natural rubber or rubber, and can weld.Preferably, be greater than 1 newton in the prolongation of low compressive force, but less than 100 newton, 20 newton preferably.

One central barrier layer 9 plays the effect of protection product 33, and it is used for masking light radiation and/or gas diffusion, for example oxygen diffusion, and can be by for example, aluminium is formed.

The same with inner wall layer 8, the outer wall layer 10 of bag film layer 7 also can advantageously be made up of thermoplastic plastic, for example PE, PP, PET, PA or other natural rubber or rubber, and greater than 1 newton, but less than 100 newton, preferably has prolongation under 20 newton's the low compressive force.

In an exemplary embodiment, bag film can have the inner wall layer 8 of 40 μ m PE, the barrier layer 9 of 7 μ m aluminium and the outer wall layer of 12 μ mPET.All these thickness specifications can have up or down 10% or 20% or more different, and namely the thickness of PE layer can be for example 40 μ m ± 10 or 20%, but also can be bigger.

Under the effect of light, the reduction that is manufactured to predetermined breaking 2 can have a degree of depth 11, it is advantageously until the surface of barrier layer 9, thereby it is minimum being used in that the pressure of opening bag film layer 7 applies, and this moment, the function of barrier layer was unaffected or seldom influenced.Yet predetermined breaking 2 also can be produced by additive method, for example, passes through scratch.

When predetermined breaking 2 produced, the integraty of the most beneath at least barrier layer 9 can be guaranteed by the method for Nd:YAG or CO2 LASER Light Source.

Fig. 1 d has shown the birds-eye view by the predetermined breaking 2 of the different exemplary shape 13a of the effect generation of light.Selection for difformity 13a, be favourable from the maximum reduction of center 14 beginning of predetermined breaking 2, when bag film 1 begins to open from predetermined breaking 2, thereby produced unified protrusion 30, and therefore can realize unified outside shape 13, and influence the angle of spray 41 of product.But the maximum reduction of predetermined breaking 2 can also can be used other forms not from its center.But star 13 is preferred predetermined breaking shapes.

Fig. 2 has shown the 3-D view of an exemplary lid 15, the predetermined breaking 2 of lid 15 cover film bags 1.For example, the size of the lid 15 of predetermined breaking 2 is determined that by the cross-sectional area of emptying chamber 24 therefore, in the process by operator/machine transportation or operation, the point that contacts with product can keep health and cleaning in emptying chamber.Like this, in the process of emptying bag film 1, the bacterial contamination of the product 33 that is caused by germ can be avoided.For example, mode by adhesives, lid 15 can be fixed on the bag film 1, and for convenience the operation of operator/machine is to remove lid from the bag layer, and described lid 15 also comprises the tongue 16 of a lid, and it is not that mode by adhesives is fixed to bag film, but can be started, like this, tongue and tractive by catching lid can separate lid 15.

Fig. 3 a has shown the exemplary pumping equipment 17 part lateral plans with the bag film 1 that inserts emptying chamber 24, and pressure device 18 stops/leans against on the pumping equipment.The exemplary location of bag film 1 causes bubble 34 to be positioned at the opposite of bag film predetermined breaking.Emptying chamber 24 can have at least one egress hole 36, and it connects by product chambers 32.In addition, pressure device 18 can comprise a compressible mat 21.Same, emptying chamber 24 can have a flushing to connect, and can wash the part of product chambers or emptying chamber and the part of bag film by this connection, for example, and with commingled water (bubble-tight or be mixed with CO2's).

Fig. 3 b has shown in the process steps snapshot of the bag film 1 that emptying is inserted, the side cross-sectional views of an exemplary pumping equipment 17.

Pressurization by pressure device 18, wall of container 7 can extend in the egress hole 36 of emptying chamber and form in this process and protrude 30, thereby the prolongation that causes predetermined breaking 2 rents exceeds and opens bag film 1, and product 33 just can flow out bag film like this.Advantageously, the compression motion of pressure device can increase at leisure, for example, at 5 to 30 seconds, or in 1 to 100 second, be increased to 200kPa from 0, or be increased to 500kPa or more from 0, for example in order to realize spraying phenomenon better, for example, by limits product from the product angle of spray of bag film ejection less than 180 °.

Emptier can be designed to like this: pressure device can arrange in a controlled manner.In this course, pressure device uses suitable method to adjust the position, and this location is not subjected to the existence of bag film, and whether institute influences.For example, pressure device is to move with a speed default and continuous variable fully, and this is not subjected to the existence of bag film, and whether institute influences.Default speed can be, for example 0.1,0.5,1.0,2.0,5.0,10,20 or 40 mm/min or more.Default speed also can be lower than in these values.

For example, in 5 to 30 seconds or 1 to 100 second, the variation of pressure can from 0 to 200kPa or from 0 to 500kPa.This will help to realize that an in check pressure increases in bag film, and therefore can avoid unexpected or uncontrolled the falling of pressure device, and can avoid throwing open with unexpected container.For this situation, for example, come mobile pressure device by hydraulic way or electronic mode, wherein pressure device kinematic velocity with one the definition hydraulic pressurization flow velocity/propellant in hydraulic actuating cylinder or motor, so that pressure device moves, or with one the definition motor running speed (for example an electro-motor, for example a stepping or asynchronous motor) define.For example, as explained above, by the mode by electro-motor or hydraulically powered thread rod, also can realize control or the pressurization of pressure device.

For example, realize the speed of bag film emptying action need one minimum of control, 0.05,0.10,1.00 or 20 millimeter per minute for example, guarantees one slowly and the bag film of control is opened, and speed is lower than maximum speed 100,200 or 500 millimeters per minutes.

Pressure device can have a compressible mat 32, when pressure device reduce/when depressing, mat 32 extends in this process and protrudes in 23, reach in the zone of egress hole 36 of emptying chamber 32, do not meet obstructions, and can be by this way the product residue thing be extruded bag film, particularly in the protruding place 31 of the predetermined breaking of the bag film that is drained substantially.

Fig. 3 c has shown in the process snapshot with commingled water/mixture flushing, the side cross-sectional views of an exemplary pumping equipment 17.By sparge water import 39, can wash protrusion and the outside shape of bag film predetermined breaking and the part of emptying chamber and product chambers of bag film 30, for example, water mixes with CO2, like this, has the product residue thing hardly and stays.Therefore, in mixing can 43, can find product and the irrigation that for example serves as bland.

Fig. 4 has shown the almost completely 3-D view of the exemplary bag film 1 of emptying, it has around the outside shape 31 of the unification at the center 14 of predetermined breaking, and predetermined breaking is pressed in along stretching in outstanding 30 the forming process of bag film by pressurized operation/add and produces.

Fig. 5 has shown the side cross-sectional views of an exemplary means 17 of emptying bag film 1.Preferably, pumping equipment 17 is made up of emptying chamber 24, and the physical dimension of emptying chamber 24 can be suitable for the size of container 1 length 3b and width 3c, and like this, the container 1 of filling product can be inserted in the emptying chamber, almost without any the space.Here, the distance 26 of pressure device around the inwall 25 can be between 0.01 millimeter to 20 millimeters, but preferably 1 ± 0.5 millimeter.Thereby can avoid in pressure process, vessel pressure is entered and/or is sandwiched in the distance 26 between emptying chamber and the pressure device 18.The shape of emptying chamber 24 can be, for example, rectangle or square, wherein emptying chamber 24 can, for example, form a plate, its sidewall design or inwall 25 are higher than the container of filling product that flatly inserts respectively.

Pumping equipment can comprise a pressure device 18, for example, is furnished with a pressure plate or piston 18a, and its physical dimension is slightly less than the inwall 25 on every side of emptying chamber 24, but preferably, it can accurately be inserted in the emptying chamber matchingly.

By pressure device, pressure can be applied on the container 1 that inserts in the emptying chamber.Here, container can protrude through in the products export hole of emptying chamber, opens and emptying receptacles up to predetermined breaking.For example, as indicated above with respect to Fig. 3 b, the actuator of pressure device can be designed to by hydraulic way or electronic mode.

Pressure device can comprise a compressible mat 21 at its bottom position, and for example air cushion or elastic body can apply pressure on the bag film by them.In this course, compressible mat can reflect the profile of container, thereby forms uniform distribution of pressure with possible weld seam on container, and can realize crumple (pleat) of container.

Emptying chamber 24 can comprise the opening 36 of products export, and for example, opening 36 is positioned at bottom 27 central authorities of emptying chamber.But, also a plurality of openings can be arranged.

When the pressure device 36 of being furnished with compressible mat 21 when use applied pressure on the container of filling product, mat can extend in the products export hole 36 of emptying chamber, thus emptying receptacles better.

For example, the product chambers 32 that its volume 35 can receive complete product 33 can connect described opening 36, and wherein product 33 is arranged in the bag film 1.In addition, product chambers can comprise a product chambers egress hole 38, and for example in the vertical direction of product chambers, or for example, at downward gravity direction, wherein egress hole 38 can have a part littler than product chambers; For example, the cross-sectional plane of egress hole gathers (back-up) 42 less than 1% to 90% of the product chambers cross-sectional plane thereby produce product.For example, the width of product chambers, as 30 millimeters of diameters, and preferred egress hole is, as 6 millimeters.For example, the design of product chambers egress hole 38 can be on the direction of gravity coning extension.

In addition, the opening 35 of product chambers can comprise that a flushing connects 39 entrance 40, for example just in time in the bottom of emptying chamber 24.Preferably, for example, entrance can design tangentially.After container was drained, the commingled water that for example is mixed with CO2 can connect 39 and entrance 40 by flushing, offer product chambers and/or emptying chamber products export hole 36 under the zone, product chambers then can wash by this way.

In addition, be used for to receive product 33 and/or mix/mixing can 43 of sparge water can be arranged in the below of egress hole 38.

Reference number as used herein is as follows:

1 bag film/laminated film bag

2 predetermined breaking

The position probing of 2a bag film

The height of 3a bag film

The length of 3b bag film

The width of 3c bag film

4 diagonal positions

The center of 5 bag films

The bottom of 6 bag films

The wall of 7 bag films/bag layer

The inner wall layer of 8 bag films

The barrier layer of 9 bag films

The outer wall layer of 10 bags of layers

The degree of depth of 11 predetermined breaking

The width of 12 predetermined breaking

13 stars pre-determine breaking-down point

The difform breaking-down point that pre-determines of 13a

The center of 14 predetermined breaking

The lid of 15 predetermined breaking

The tongue of 16 lids

The pumping equipment of 17 bag films

The pressure device of 18 emptying bag films

Piston/the pressing plate of 18a pressure device

The size of 19 pressure devices

The outer rim of 20 pressure devices

The mat of 21 pressure devices

22 compressible mats

The protrusion of the mat of 23 compressions

24 emptying chambers

The inwall of 25 emptying chambers

Distance between 26 emptying locular walls and the pressure device

The bottom of 27 emptying chambers

28 containers are in the sealing of emptying chamber bottom

The bag film of 29 skies

The protrusion of bag film before the protrusion of bag film 30 skies or that be sky substantially and/or predetermined breaking are opened

The outside shape of the predetermined breaking of bag film 31 skies or that be sky substantially

The product chambers of 32 pumping equipments

Product in 33 bag films

Foaming in 34 bag films

The volume of 35 emptying chambers

The egress hole of 36 emptying chambers

The egress hole of 38 product chambers

The flushing of 39 product chambers connects

The tangential inlet that 40 flushings connect

41 in the bag film evacuation procedure angle of spray of product

Product in 42 product chambers gathers

43 mixing cans

Claims

1. laminated film bag (1), it is used for storage food, beverage concentrate particularly, has one bag of layer (7), described bag layer (7) comprises at least one skin (10), a barrier layer (9), for example, intercept oxygen and/or light, an and internal layer (8), it is characterized in that described laminated film bag is included in the predetermined breaking (2) on the bag film, described breaking-down point (2) is torn under pressure, for example surpass under the situation of 100kPa, 150kPa, 200kPa, 400kPa or 500kPa at pressure, and tear without any the part of bag film.

2. bag film according to claim 1 (1) is characterized in that, described predetermined breaking (2) is positioned on the outer layer side (10) of bag film (1), and advantageously, described predetermined breaking is positioned at the center of outer layer side (10).

3. according to an aforementioned claim described bag film (1) wherein, it is characterized in that, the prolongation of described predetermined breaking (2) less than outer layer side (10) prolongation half, 1/3rd or 1/4th, wherein, predetermined breaking (2) is positioned on the outer layer side (10).

4. according to an aforementioned claim described bag film (1) wherein, it is characterized in that, described bag film has rectangular shape and/or comprises a weld seam at least one side, and the pressure that weld seam/many weld seam bears is on the range of pressure that causes described predetermined breaking to be opened.

5. according to an aforementioned claim described bag film (1) wherein, it is characterized in that, described predetermined breaking comprises an antipollution lid (15), wherein said lid for example by adhesive, and comprises, for example, the tongue of one lid (16), wherein, the tongue (16) by lid manually or mechanically removes lid (15).

6. according to an aforementioned claim described bag film (1) wherein, it is characterized in that described predetermined breaking (2) is produced by the effect of light.

7. according to an aforementioned claim described bag film (1) wherein, it is characterized in that the degree of depth of the described predetermined breaking (2) in the described bag film skin does not arrive darker than described barrier layer (9).

8. according to an aforementioned claim described bag film (1) wherein, it is characterized in that the size that described bag film has is that its aspect ratio length and width are all little.

9. according to an aforementioned claim described bag film (1) wherein, it is characterized in that described bag film comprises a position detection marks.

10. according to an aforementioned claim described bag film (1) wherein, it is characterized in that, before described predetermined breaking (2) is torn/opens, under the effect of pressure, described predetermined breaking (2) is to outer lug, and forms a protrusion.

11. do not stay the wherein method of a described bag film (1) of the aforementioned claim of any residue ground emptying substantially, comprise that bag film is placed in the emptying chamber (24), wherein, length with respect to width and the emptying chamber of emptying chamber, the physical dimension of emptying chamber is preferably with the width of suitable bag film and the height of bag film, and apply pressure on the bag film by pressure device, thereby form one and protrude (30), when bag film layer (7) over expansion in the predetermined breaking side, then open predetermined breaking, for example, the heart therein, and bag film is drained substantially, does not almost stay any residue, wherein said pressure device (18) preferably moves with a predefined speed, to apply pressure on the bag film.

12. method according to claim 11 wherein apply uniform pressure to the surface of bag film (1) by the mat (21) that is connected to pressure device (18) bottom, and mat (21) is compressed under pressure.

13. method according to claim 12, wherein, when pressure is applied on the bag film of emptying of emptying chamber (24) bottom (27), described mat (21) is compressed, mat (21) is forced in the egress hole (36) of emptying chamber, and the protrusion by bag film layer (30) squeezes out bag film with the surplus of bag film content from described predetermined breaking, and the described bag film of emptying almost completely.

14. according to claim 11-13 described method wherein, wherein the bubble (34) in bag film (1) is arranged in the zone of vertex or evacuate position bag film height, and in evacuation procedure the resistates of bag film content is flushed out bag film.

15. according to claim 11-14 described method wherein, wherein bag film is discharged in the product chambers (32)/on, and at emptying bag film afterflush product chambers, use for example bubble-tight or be mixed with the commingled water of CO2.

16. be used for the device that the bag film (1) of the claim 1 of product is filled in emptying, comprising the emptying chamber (24) of being furnished with at least one egress hole (36) and at least one pressure device (18), it is characterized in that, described pressure device (18) moves with a predefined speed, and be pre-configured to and realize pressurization, thereby cause the emptying of the bag film of opening He having filled of the predetermined breaking of bag film (1).

17. device according to claim 16, it is characterized in that, pressure device (18) is configured to and can moves with a speed predefined and/or continuous variable, for example speed or be higher than 0.1,0.5,1.0,2.0,5.0,10,20 or 40 mm/min, and/or be configured to 5 to 30 seconds or in 1 to 100 second, reach 0 to 200 or the pressure of 500kPa change, and/or be configured to realize that pressure is applied to bag film (1) and goes up and surpass 50kpa, 100kPa, 200KPa, 400kPa or 500kPa.

18. according to claim 16 to 17 described device wherein, it is characterized in that the bottom of described pressure device comprises the piston of being furnished with compressible mat (21), for example an elastic body or an air cushion.

19. according to claim 16 to 18 described device wherein, it is characterized in that, described pressure device around the inwall (25) of described emptying chamber (24) distance (26) between 0.01 millimeter to 20 millimeters, preferably 1 millimeter.