Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D31/00—Bags or like containers made of paper and having structural provision for thickness of contents
  • B65D31/14—Valve bags, i.e. with valves for filling
  • B65D31/142—Valve bags, i.e. with valves for filling the filling port being formed by folding a flap connected to a side, e.g. block bottoms

Definitions

• the present invention relates to a valve bag made in particular/of plastic film, provided with a filling opening valve and at least one venting / which is covered by at least an a i r - p e r m e a b l e and dust-filtering material.
• the filling material When filling valve bags with pulverulent material such as starch powder, cocoa and cement, the filling material is fluidized with the aid of air and the air/ filling material mixture is blown into the bag via a filling spout inserted in the filling valve. Since the required air/filling material ratio in the mixture depends on the type of filling material, the venting capacity of the sack necessary for satisfactory filling during filling is also dependent on the type of filling material. The venting capacity of the bag in many cases has a great influence on the filling speed to be attained.
• the following three phases can be distinguished, i.e. a first phase in which the bag is not yet completely filled with air and filling material, a second phase in which the bag is completely filled with air and filling material but in which the bag does not yet contain sufficient filling material, and a third phase in which the bag is completely filled with filling material but in which filling material is still present in the filling spout .
• the filling speed does not depend on the venting capacity of the bag .
• the air which is additionally blown into the bag has to be discharged via the vent of the bag .
• the filling speed then depends on the venting capacity of the bag .
• valve bags of the type mentioned at the outset are known in various embodiments.
• the venting opening or openings covered by an air-permeable and dust-filtering material serves or serve to allow the air present in the bag to escape from the bag during filling of the bag with, in particular, pulverulent or more or less fine-grained material, without filling material escaping from the bag .
• the wall of the bag is provided over a given area with perforations serving as venting openings and covered by an air-permeable and dust-filtering material.
• a venting tube is fitted in the bag a n d consists completely or partially of an air-permeable and dust-filtering material, such as non-woven.
• a small air-permeable fiIter pocket is provided in the bag opposite the filling valve and consists of a non-woven.
• Dutch Patent Application 78.04027 discloses a valve bag having a tubular filling valve which consists of film material and is surrounded by a filter layer consisting of an air-permeable and dust-filtering material, through which the interior of the bag is inc o n n e c t io n i t h t h e e x t e r io r o f t h e ba g .
• I n a n o t h e r embodiment of this known valve bag the entire filling valve consists of a tube of air-permeable and dust- filtering material.
• venting capacity of the known valve bags is often limited and as a result only a limited filling speed can be achieved.
• This may be the consequence of the fact that the air-permeable and dust-filtering material, such as a non-woven, has the tendency during filling of the bag become blocked, i.e. that the pores in the filter material are blocked by the filling material particles entrained in the air escaping from the bag .
• the fact that during filling of the bag under production conditions it is difficult to provide the filter with a sufficiently large open venting surface may be another cause of the limited venting capacity.
• valve bag of the type mentioned at the outset which is characterized in that the filling valve comprises in air-permeable and dust-filtering section which extends essentially over the length of the filling valve sec on extending within the bag and in that the filling valve is provided at the end located inside the bag with a constriction.
• the innermost part of the filling valve embraces the filling spout during insertion of the filling spout in the filling valve and the filling valve can be pulled tight.
• the filling valve is advantageously designed as a tubular sleeve which narrows towards the interior of the sack, so that the filling valve can be uniformly pulled tight.
• the filling valve is preferably assembled from two strips of material which are joined to each other along the edges, at least one of the two strips consisting at least partially of an air-permeable and dust-filtering material.
• a tubular filling valve of this type can be manufactured in a simple manner. It has been found, surprisingly, that the nonwoven in a valve bag of the type mentioned at the outset in which the air-permeable and dust-filtering material is a nonwoven, does not have the tendency to become blocked when nonwoven it consists of spunbonded . By using a spunbonded nonwoven as air-permeable and dust-filtering material a bag having a high venting capacity can be obtained. As a result, the filling time of the bag can be shortened and the range of application of valve bags made of plastic film can be considerably increased.
• a nonwoven is frequently applied mechanically.
• the nonwoven material at the same time usually has a sufficient stiffness to be processed mechanically.
• Certain nonwoven materials such as spunbonded nonwoven which are extremely suitable for serving as cover for vent ingopenings in valve bags because they have very good filter properties and do not become blocked with the material particles entrained in the air escaping from the bag have, however, a very low stiffness compared with the film material of the bag and other conventional non-woven materials and as a result are very difficult to process mechanically.
• the nonwoven is mounted on a carrier film having a sufficient stiffness to be processed mechanically.
• nonwoven is a spunbonded nonwoven but can, of course, also be used with other nonwovens and air-permeable and dust-filtering materials having low stiffness.
• the invention also relates to a filling spout for filling valve bags which is characterized in that the filling spout is provided on the outside with means for keeping the wall of the filling valve at a distance from the wall of the filling spout when the filling spout is inserted.
• Figure 1 diagrammatically shows a part of a valve bag having a filling valve according to the invention
• FIGS. 2 to 6 incl. diagrammatically show various stages during manufacture of a valve bag according to the invention
• Figure 7 is a diagrammatic section of a corner of a valve bag according to the invention in the region of the filling valve;
• Figure 8 is a view along line VIII-VIII in Figure
• Figure 9 is a diagrammatic section of a corner of modified embodiment of a valve bag according to the invention in the region of the filling valve;
• Figure 10 is a view along line X-X in Figure 9;
• Figure 11 gives a diagrammatic picture of the manufacture of a filling valve for a valve bag according to the invention.
• Figure 12 shows a filling valve, manufactured according to Figure 11, for a valve bag according to the invention
• Figure 13 shows another embodiment of a filling valve for a valve bag according to the invention.
• Figure 14 diagrammatically shows the manufacture of a filling valve according to Figure 13;
• Figure 15 shows yet another embodiment of a filling valve for a valve bag according to the invention.
• Figure 16 shows yet another embodiment of a filling valve for a valve bag according to the invention.
• Figure 17 diagrammatically shows a filling spout preferably to be used during filling when this filling spout is inserted in a filling valve;
• Figure 18 is a cross section through a filling spout according to Figure 17 at the position of the ribs;
• Figure 19 diagrammatically shows an alternative embodiment of a filling spout to be used during filling when this is inserted in a filling valve
• Figures 20 to 23 incl. diagrammatically show the consecutive steps during manufacture of a valve bag according to the invention with venting tube.
• Figure 1 shows a section of a valve bag 1 made of plastic film and provided with a tubular filling valve 2.
• the filling valve 2 is located In the region of a bottom of the valve bag 1.
• the bottom of the valve bag 1 is covered by a cover sheet 3;
• Figures 2 to 6 incl. diagrammatically show the various stages of manufacture of a valve bag according to Figure 1.
• Figure 2 shows a tubular film section 4 from which a valve bag according to the invention is manufactured.
• the top of the tube film section 4 is provided all round its outside with an adhesive layer 5.
• the uppermost end 6 of the tubular film section is folded in a conventional manner as shown in Figure 3, bottom flaps 7 and 8 and corner flaps 9 and 10 being produced.
• the filling valve 2 is also arranged in the conventional manner at the position of the corner flap 10 on the unfolded upper part of the tubular film section 4 as shown in Figure 4. The construction of the filling valve will be described in detail in the text below.
• Figure 7 diagrammatically shows a section of a corner of a valve bag in the region of the filling valve 2, while figure 8 is a bottom view along line VIII-VIII in Figure 7.
• Figure 7 and 8 also show diagrammatically the construction of the filling valve 2.
• the filling valve 2 is tubular and comprises and air-permeable and dust-filtering section which extends essentially over the length of the section, extending within the bag, of the filling valve.
• the filling valve 2 is built up from two strips of material 12 and 13, the strip 12 located at the side of the adjacent bag bottom consisting of film material and the other strip 13 consisting of an air-permeable and dust- filtering material. The two strips are joined to each other and their sides by means of connecting seams 14.
• the filling valve 2 is provided with a constriction 16.
• this is achieved by constructing the filling valve 2 as a tubular sleeve which narrows towards the interior of the bag .
• the constriction 16 will fit tightly around the outside of the filling spout inserted in the filling valve, and as a result the entire filling valve can be pulled tight.
• Matching the shape of the filling valve to that of the filling spout makes it possible to ensure that a certain space is produced between the outer wall of the filling spout and the air-permeable and dust-filtering material, which is pulled tight, of the filling valve.
• Figures 9 and 10 essentially correspond to Figures 7 and 8 with the difference that the edges of the bottom flaps 7 and 8 of the bag do not touch each other, so that a so-called "negative overlap" 17 is produced.
• the strip 12 of film material of the filling valve 2 is located on the side of the adjacent bag bottom and the air-permeable and dust-filtering strip 13 is located on the side of the interior of the bag .
• This embodiment has the advantage that the filter is located on the side where there is the most space. Furthermore, the filling material which arrives at the filter during filling will have the tendency to fall downwards again so that the tendency for the filter layer to block up is low.
• This embodiment has the advantage that, during "inflation" of the bag during filling, the air present in the bag c a n e s c a pe f r o m t h e ba g v ia t h e s p a c e b e t w e e n t h e bag bottom and the filling valve. Furthermore, this embodiment achieves the result that, after the bag has been filled, the filling valve is sealed very tightly by the relatively stiff film layer which is pressed against the bottom of the bag .
• the two strips of the filling valve may consist of air-permeable and dust-filtering material, so that venting can take place via both sides of the filling valve.
• at least one of the two strips may be provided with a cover layer of relatively stiff material, which cover layer is provided with perforations such that the strip provided with a cover layer is sufficiently air-permeable.
• Figure 11 diagrammatically shows the manner in which a filling valve 2 for a bag according to the invention can be manufactured.
• the starting point is formed by a roll of film material 18 and a roll of air-permeable and dust-filtering material 19.
• the width of the two rolls 18, 19 corresponds to the width of the filling valve 2 to be manufactured.
• the strips obtained from the two rolls a r e joined to each other along their edges with the aid of a welding roller 20 and a backing roller 21 and are cut into pieces by means of a knife 22 mounted on the welding roll.
• a filling valve 11 is produced which is built up of a strip of film material 12 and strip of air-permeable and dust- filtering material 13, which two strips are joined to each other by means of connecting seams 14 (see Figure 12).
• Figure 13 shows an alternative embodiment of a filling valve for a valve bag according to the invention.
• the filling valve 2 shown in Figure 13 is composed of a first strip of film material 24 having a length which is greater than the length of the section, extending within the bag , of the fil ling valve 2' and a second strip 25 which is joined along the edges to the strip of film material 24 by means of connecting seams 26.
• the second strip 25 consists of a strip part 27 of air-permeable and dust-filtering material and a doubly folded strip part 28 made of film material which, along the folding edge 29 transverse to the longitudinal direction of the filling valve 2' is joined with the strip part 27 made of air-permeable and dust-filtering material.
• the length of the second strip 25 is essentially equal to the length of the first strip of film material 24, the length of the strip part 27 essentially corresponding to the length of the section, extending within the bag , of the filling valve 21.
• Such an embodiment of a filling valve has the advantage that, after filling of the bag , the extension piece 30 of the filling valve 21 can be doubly folded and can be arranged in a space below the fil ling opening of the bag , so that a satisfactory seal of the into the bag filling valve is achieved and water leakage/ and backflow of filling material via the filling valve is prevented.
• Figure 14 diagrammatically shows the manner in which a filling valve 2 according to Figure 13 can be manufactured.
• the starting point is formed by a roll of film material 31, a roll of air-permeable and dust-filtering material 32 and a second roll of film material 33 for the doubly-folded part strip 28.
• the web, of dust-filtering and air-permeable material fed from the roll 32 has been joined with the web, of film material fed from roll 33, the web assembled and the web of film material fed from roll 31, are joined to each other and cut into pieces in the manner shown in Figure 14, so that filling valves 2' as shown in Figure 13 are formed.
• Figures 15 and 16 show two other possible embodiments of a filling valve for a valve bag according to the invention.
• the strips 34 and 35 of which the valve is assembled each consist of a strip part 36 of air-permeable and dust-filtering material and a strip part 37 made of film material which is joined along edge 38 with strip part 36.
• the two strips 34 and 35 are joined to each other along the sides by means of connecting seams 39.
• the filling valve/ according to Figure 16 is assembled of two strips 40 and 41 which each correspond to the strip 25 of the valve according to Figure 13.
• the two strips 40 and 41 are joined to each other along the sides by means of connecting seams 42.
• This valve also has an extension piece 43 which, after filling of the sack, can be doubly-folded so that the filling valve is sealed tightly.
• FIG 17 and 18 diagrammatically show a filling spout which is preferably used during filling of a valve bag according to the invention.
• the filling spout is inserted in a fil ling valve 2 of a bag.
• the fil ling spout 44 is provided over at least part of the outer wall 46 with spacers 45 which extend outwards and which serve to keep the wall of a filling valve 2 at a distance from the wall 46 of the filling spout 44 when the filling spout 44 is inserted.
• the spacers consists of raised ribs which extend in the longitudinal direction of the filling spout 44.
• Figure 19 shows an alternative embodiment of a filling spout -
• the filling spout 47 is surrounded by a tubular sleeve 49 which is arranged at a distance from the outer wall 48 and is made of a material provided with openings such as gauze or perforated sheeting.
• the wall of the filling valve is held by this tubular sleeve at a distance from the wall 48 of the filling spout 47.
• the filling valve 2 can be held firmly on the tubular sleeve 49 by means of a clamping member 50.
• a clamping member 50 it is ensured that the air present in the bag can always flow outwards unhindered during fil ling.
• a valve bag made of plastic film of the type having a filling valve and a venting opening covered by an air-permeable and dust-filtering nonwoven very good venting is obtained when the nonwoven consists of a spunbonded nonwoven.
• a spunbonded nonwoven is particularly suitably manufactured from continuous fibres having a thickness of 5-10 ⁇ m which are joined to each other thermally or mechanically without use of additional material.
• a spunbonded nonwoven of this type is marketed under the tradename Lutravil®.
• the fibre material may be polypropene, polyethene, polyamide or polyethene terephthalate. It is preferable to manufacture the film of the bag and the nonwoven of the same material so that the film material and the nonwoven material can be recycled together after use of the bag .
• the bag is usually manufactured from polyethene film it is preferable to manufacture the nonwoven from polyethene fibres.
• the thickness of the nonwoven can be chosen on the basis of requirements to be met by the venting. Depending on the requirements, a nonwoven can be chosen having a weight between 5 and 10 g/m 2 .
• a bag of the type described in Dutch Patent pocket Application 78.11426 having a small filter manufactured of spunbonded nonwoven can be filled within a filling time of 8 to 12 seconds with a large variety of powders, it being possible for the particle size to vary pocket between 1 and 200 ⁇ m, without the small filter becoming blocked and without dust penetration taking place.
• a high venting capacity can also be achieved by using a spunbonded nonwoven as cover material for the venting opening or openings in other types of valve bags , for example those in which the venting takes place via perforations provided in the wall of the bag over a certain area and covered by a nonwoven or those in which venting takes place via a venting tube or venting valve.
• a spunbonded nonwoven as described above generally has too low a stiffness to be provided readily mechanically in a valve bag. Before being attached to the bag, the spunbonded nonwoven is therefore mounted on a carrier film which has sufficient stiffness to be able to be processed mechanically.
• Figures 20 to 23 incl. show how a dust-filtering and air-permeable nonwoven having low intrinsic stiffness can be fitted in a valve bag. with venting tube in one of the bottoms.
• a filling valv e 5 1 o f f i l m m a t e r ia l is f it t e d in t h e c o n ve n t io n a l m a n n e r at the position of the corner flap 10 on the unfolded upper section of the tubular film section ( Figure 20).
• the filling valve 51 is for this purpose provided all round with an adhesive layer 52 which is bonded to the adhesive layer 5 of the corner flap 10.
• Figure 21 shows the manner in which the venting tube of the valve bag is manufactured and fitted on the pre-formed bag section of Figure 20.
• a film web 60 made of the same material as the material of the tube film section 4 is unrolled from a roll 61.
• a web 62 of the nonwoven material for covering opening the venting of the valve bag to be manufactured is unrolled from a roll 63 and joined to the film web 60 by means of two longitudinal seams 64.
• the film web 60 serves as a carrier for the nonwoven 62.
• the thus formed, assembled web is cut into sections having the desired length as a result of which sheets 65 are produced.
• the nonwoven 62 is at the same time joined to the carrier film transverse 60 by means of a weld 67 at the end 66 of each sheet 65 which will be fitted at the position of the filling valve 52 on the bag.
• a tubular section open at one end is thus produced which will serve as venting tube for the valve bag.
• the sheet 65 is subsequently provided at the two ends 66 and 68 on the upper and lower side with an adhesive layer 70, the adhesive being provided at the end 68 on the lower side of the nonwoven 62. This ensures that at this position no adhesive gets between the nonwoven 62 and the carrier film 60.
• the sheet 65 provided adhered with adhesive layers70 is on the pre-formed bag end of figure 20, adhesive layers 70 adhering to adhesive layers 5.
• a bag end as represented in figure 22 is produced.
• the bottom flaps 7 and 8 are subsequently folded inwards.
• the bag end is covered in the usual manner with a cover sheet 71 as shown in figure 24.
• the other bag end is formed in the conventional manner.
• the nonwoven can also be joined to the carrier film in another manner, for example by welding.
• various types of carrier film such as continuous carrier film and carrier film provided with perforations.
• a combination of a nonwoven having low stiffness with a carrier film can be used for various types of valve bags . for example in a tubular filling valve described above made of two strips, the nonwoven functioning separately from the carrier film during filling of the bag.
• a carrier film can also be used with other air-permeable and dust-filtering materials having low stiffness.
• valve bag By using a carrier film a valve bag can be manufactured mechanically with a venting hole or venting holes which is or are sealed by a nonwoven having excellent properties in respect of air-permeability and very dust-filtration but which per se has only/ low stiffness.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Bag Frames (AREA)

Applications Claiming Priority (6)

Publications (1)

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• 1988
  • 1988-05-10 EP EP19880904275 patent/EP0367769A1/de active Pending
  • 1988-05-10 WO PCT/NL1988/000021 patent/WO1988008816A1/en not_active Ceased
  • 1988-05-10 AU AU17181/88A patent/AU1718188A/en not_active Abandoned
  • 1988-05-10 EP EP88200922A patent/EP0291128A1/de not_active Withdrawn

Non-Patent Citations (1)

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