The invention relates to a container, such as a carrier bag, manufactured from weldable sheet material and comprising a first, a second, a third and a fourth layer of sheet material which have a substantially mutually corresponding form and which are mutually connected on all their edges, with the exception of a connection between the second and the third layer on the upper side, wherein the space between the first and the second layer and the space between the third and the fourth layer are mutually connected and these spaces together form an air chamber, and wherein a channel extends between the air chamber and the surroundings, which channel at least partly comprises a wall which is manufactured from limp material and which is bounded on its outside by the air chamber.
Such a container is known from NL-A-1011793.
Such a container can for instance be applied as carrier bag for fragile products, such as glass bottles and glassware or for products requiring thermally insulated transport, such as deepfreeze products or cooled drinks. Particularly in the case of cooled drinks it is important that the thermal insulation is maintained for a long time, for instance during a day at the beach.
In this prior art container there occurs minor leakage in the channel serving as closure, so that the pressure prevailing in the interior of the container cannot be maintained sufficiently long enough to ensure a comfortable use of the said container.
The present invention has for its object to provide such a container wherein the pressure prevailing in the interior can be maintained for a sufficiently long period of time.
This object is achieved in that the channel comprises a rigid part accessible on the outside which can be closed by a cap.
Providing a rigid part and a cap will of course have the effect of increasing the cost price, but does result in a much better utility of the container. The limp part of the channel herein acts as a means for reducing the leakage of air through the channel during the period between the end of the inflation and placing of the cap.
It is pointed out here that a similar configuration is known from FR-A-2121977, but that use is herein made to blow in air of a tube which is removed afterward.
According to a first embodiment the limp wall of the channel is formed by strips of the first and second layer folded at a sheet edge.
It hereby becomes structurally simple to integrate the limp part of the channel in the container.
According to another preferred embodiment the rigid part of the channel is formed by a tube which is enclosed in airtight manner between both strips and which can be closed on its outside by a cap. This embodiment makes it possible during manufacture of a container to slide such a tube in between the layers of sheet material and to adhere it thereto.
A particular embodiment teaches that the connecting weld between the folded strips is interrupted at the position of the channel by a layer arranged prior to the welding and blocking the adhesion of the weld.
In order to seal the space for inflating use is made of a weld between the sheet material and the folded parts thereof. This weld must be interrupted at the position of the channel in order to close the channel to the space for inflating. It is difficult to interrupt a weld once it has been made. This problem is avoided by preventing the weld from being made. Preventing the weld from being formed locally can be achieved by arranging a layer preventing adhesion at the relevant location. An operation is saved by arranging the layer together with the printing.
The present invention further provides a method for manufacturing such a container, comprising the following steps of: printing one side of a strip of material at least at the position of the channels to be formed, folding the strip of material in two in the length, folding flaps situated on the edges of the strip inward in the length direction, adhering the flaps along their edges to the material lying opposite, folding the strip of material in two once again, adhering the material along the transverse edges, inserting and adhering the tube and cutting off the thus resulting containers.
Other attractive embodiments of the invention are stated in the remaining sub-claims.
The present invention will be elucidated hereinbelow with reference to the annexed figures, in which:
Figure 1 shows a carrier bag designated as a whole with 1, which is shown in cross-section in figure 2. The carrier bag is formed by two outer panels 2 respectively 3, and two inner panels 4 respectively 5. Inner and outer panels 2-5 are together formed from one sheet of flexible material. On the upper side of the carrier bag the outer panel 2 and inner panel 4 are connected to two folded strips 6 respectively 7, which also form part of the same sheet of basic material. The folded strip 6 is connected to outer panel 2 by means of a weld 8, while folded strip 7 is connected to inner panel 4 by means of a weld 9. A sealing weld 11 is arranged to seal the space 10 enclosed by panels 2-5. This weld 11 is interrupted at the position of the air supply device, as will be elucidated in the following. A handgrip 12 respectively 13 is fixed to each of the inner panels 4, 5 by means of welds 14 respectively 15,
Between panels 2 and 4, respectively between 3 and 5 are further arranged a number of connecting welds which are only shown in figure 2. Side welds 17 respectively 18 are arranged on both sides of carrier bag 1. The thus obtained space 10 is therefore sealed in airtight manner relative to the surroundings, apart from the interruption in weld 11.
Figure 3 shows how a channel is formed for supplying the air to the space in question. As shown in figure 3, the weld 11 is interrupted for this purpose between folded strips 6 and 7. At the position of this interruption a plastic tube 19 is placed between the folded strips 6 and 7. This tube 19 extends to a position some distance from the interruption of seam 11. The tube is herein sealed fixedly between the folded strips 6 and 7 by means of two seams 20 respectively 21. Seams 20 respectively 21 diverge from the tube to a connection with the original seam 11. Between the interruption in weld 11 and the tube 19 the space between the two strips 6, 7 is sealed by welds 20, 21.
In order to improve the adherence of tube 19 to folded strips 6, 7, tube 19 is provided with two protrusions 22 respectively 23 extending in the length direction of tube 19.
Two welds 32 further extend over the tube for airtight sealing of the tube 19.
The part of inner panel 4 enclosed by welds 11, 20 and side weld 18 is further provided with a perforation 24, whereby a releasable tongue 25 is formed. Formed at the tip of this releasable tongue 25 is a stopper 26 which can be placed into the opening of tube 19 after the perforation has been broken away. A sufficiently precise sealing is hereby obtained.
Figure 4 shows how the recess in weld 11 is obtained. The relevant part of folded strip 7 is provided for this purpose with a printing 27. This printing can be formed by a colourless printing, for instance by a colourless lacquer, but can equally well be formed by a coloured printing. This printing can be arranged together with the usual printed advertising on outer panel 2.
In a welding operation taking place after the printing the weld will not adhere at the position of the printing, so that the desired recess in weld 11 is thus obtained.
The manufacture of a carrier bag according to the invention will now be described with reference to figures 5ah.
The starting point is a length of LDPE 28 as shown in figure 5a. Arranged on this length is printed advertising 29 as well as the printing 27 intended for the purpose of forming a recess in weld 11.
Strips 6 and 7 are subsequently folded as shown in figure 5b. Welds 8 and 9 are then made as shown in figure 5c.
Yet another fold is made in order to obtain the configuration as shown in figure 5d, whereafter weld 11 is made and a weld 30 can be made as shown in figure 5e. Side welds 17 and 18 are then made, as shown in figure 5f, and tube 19 is inserted as shown in figure 5g.
Finally, handgrips 12 and 13 are arranged and the thus created carrier bag is folded in two as shown in figure 5h, whereafter only the side welds 17, 18 not shown in the cross-section have to be made to complete the carrier bag.
It will be apparent that it is possible to depart from the embodiment in numerous ways; it is for instance possible to manufacture a carrier bag from other material or to manufacture a carrier bag with a different shape. This shape can for instance be chosen on the basis of the materials for transporting, for instance glass bottles or deepfreeze products. The carrier bag can also be adapted to serve as a pillow, whether or not it is filled with cans of cooled drinks.
Although provision has now been made to manufacture the carrier bag from the usual materials such as LDPE, other materials such as composite foils, particularly foils provided with a metal layer, are not precluded.