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
  • B65D33/00—Details of, or accessories for, sacks or bags
  • B65D33/01—Ventilation or drainage of bags

Definitions

• the invention relates to multi layer sleeve valve sacks. Particularly the invention concerns the escape of air from the sack during the filling of the sack.
• the rate of escape of air through the sack sheath is parallel to the sheath surface area.
• the air permeability of the sheath should be correspondingly improved.
• a sack according to the invention is essentially characterized in that there are channels on the outer surface of the inner layer, along which the air that has moved through the inner layer is allowed to escape from the space between the layers.
• the air permeability of the sheath is essentially improved without perforation of the sack.
• air from the point of view of the invention, can refer to any gas used during the filling stage.
• Channels between the layers also increase the friction between the layers thus adding to sack strength.
• the invention is particularly useful when a moisture barrier is used in the sack. It is placed outside the channels. Depending on the circumstances, the moisture barrier can even be lightly perforated to improve air permeability yet maintaining adequate moisture barrier properties.
• the inner layer is porous and strong sack paper with good air permeability. Paper which is porous enough needs no perforation which means than no material leakage occurs, not even between the layers.
• the outer layer may be of any material suitable for the purpose.
• the channels are preferably made to the paper before the final drying in the process of manufacture, since then the channels do not essentially weaken the paper by breaking the fibres.
• Figure 1 shows the sheath layers of a two-layer sack according to the invention
• Figure 2 shows an alternate embodiment of the sack in Fig. 1 .
• Figure 3 shows a bottom of a sack according to the invention.
• a sack sheath there is an inner paper layer 1 , an outer paper layer 2 and, between these layers, a moisture barrier layer 3.
• the inner layer 1 On the outer surface of the inner layer 1 there are parallel channels 4.
• the inner layer 1 has good air permeability. Its air permeability resistance according to the
• Gurley standard is, e.g., 6 ⁇ 2 s.
• air moves through the inner layer 1 to the channels 4 and flows along the channels away from the space between the layers.
• the basis weight of the inner layer 1 is 90 g m 2
• the thickness of the layer is approx. 70 ⁇ m of which the depth of the channels 4 is, e.g., approx. 15 - 20 ⁇ m.
• the width of the channels is, e.g., 2 - 5 mm and the space between them is, e.g., 1 - 2 mm.
• the moisture barrier 3 is of suitable plastic, such as polyethylene of 10 - 15 ⁇ m. It is adhered only from the mouth regions of the sack to the paper layers 1 and 2 by light dot adhesion.
• the moisture barrier can nevertheless also be a layer laminated on the paper surface.
• the moisture barrier is preferably on the inner surface of the outer layer.
• the moisture barrier can be lightly perforated to improve air permeability.
• suitable perforation quantity is, for example, only 30 - 40 % of what is conventionally used.
• the inner layer may also consist of several sublayers.
• the channels are preferably placed on the outer surface of the innermost sublayer.
• the other sublayers may also be channelled.
• the outer layer is made of paper with strength properties suitable for the purpose.
• the outer layer may also consist of several sublayers.
• the outer layer 2' is made of channelled paper in which the channels 5 are on the inner surface. This way the over- pressure in the channels 4 pushes the moisture barrier film 3 into the channels 5 on the outer layer, and the cross-sectional area of the air flow channel between the film and the inner layer 1 correspondingly grows.
• FIG. 3 shows the bottom of a sack in a filling situation.
• the front side of the sack is folded to the bottom area to form a topmost overlap flap 6.
• a bottom cover sheet 8 is further attached.
• the bottom cover sheet 8 is attached with adhesive seams 9, 9.1 and 10 in the longitudinal direction of the bottom, which seams may be either continuous or broken.
• the bottom cover sheet does not have any adhesive applied to it, as a result of which a channel 1 1 in the longitudinal direction of the bottom is formed at this area, along which channel air is allowed to escape from the bottom ends.
• a channel 1 1 in the longitudinal direction of the bottom is formed at this area, along which channel air is allowed to escape from the bottom ends.
• the bottom cover sheet is preferably made a little shorter than the bottom so that during the filling stage the end 13 of the sheet does not close the air channel of the bottom against the end fold 14 of the bottom.
• the overlap flap of the back side of the sack is folded topmost to the bottom area, which allows the air to escape from both ends of the sack.

Landscapes

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

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8556650

Family Applications (1)

Country Status (5)

Cited By (5)

Families Citing this family (1)

Citations (4)

• 1996
  • 1996-06-05 ES ES96917509T patent/ES2227589T3/es not_active Expired - Lifetime
  • 1996-06-05 WO PCT/FI1996/000334 patent/WO1997046460A1/en active IP Right Grant
  • 1996-06-05 DE DE69633414T patent/DE69633414T2/de not_active Expired - Fee Related
  • 1996-06-05 EP EP96917509A patent/EP1040047B1/en not_active Expired - Lifetime
  • 1996-06-05 CZ CZ19983899A patent/CZ293746B6/cs not_active IP Right Cessation

Patent Citations (4)

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