IL30033A - Valve bag - Google Patents

Description

VALVE BAG This invention relates to a valve bag suitable for ί§ ^ manufacture by automatic bag-making machines.

Valve bags are in general use for packaging materials such as fertilizers and cement. These bags possess the important commercial advantage of easy filling and closing after filling.

However, the presence of the valve in the bag structure introduces problems in bag manufacture and may require manual operation of certain steps in the manufacturing process. There is thus need for a valve bag of simple construction that can be manufactured employing automatic bag-making machines.

It has now been discovered that a valve bag having the valve constructed of overlapping panels in the bag gusset can be manufactured employing automatic bag-making machines. The novel design of bag permits an increased rate of production and requires a minimum of manual operations.

It is therefore a primary object of this invention to provide a valve bag that is readily manufactured employing automatic bag-making machines. Additional objectives will appear hereinafter .

The valve bag of this invention comprises front and back panels joined along two opposed edges to form a flattened tube, the remaining two opposed edges of the front and back panels being joined by gusseted end panels, one of said end panels being formed of two portions having lengths less than the length of the gusseted end panel, said portions overlapping at their inner extremities, the inner extreme edge of each portion being free, thus forming a valve. It is convenient to employ thinner gauge film at the free extremities of the valve walls, the thinner extension in the case of the external valve wall being folded back to lie in contact with the internal valve wall.

The invention is illustrated by the accompanying drawings wherein Figure 2 is a perspective view of the bag of Figurejl in a collapsed configuration; Figure 3 is a sectional view of simple valve; Figure 4 is a sectional view of a valve having an extension of thinner gauge film joined to the free extremity of the inner wall of the valve; Figure 5 is a sectional view of a valve having extensions of thinner gauge film joined to the free extremities of both walls of the valve, and Figure 6 is a sectional view along VI of Figure 1.

Referring to the drawings , in Figures 1 and 2 front and back panels of a bag are shown at 1 and 2 respectively. The back panel is disposed in parallel relationship to the front panel. Front and back panels are joined along longitudinal seams 2a and 2b. At 3 are shown diagonal seals in the gusset region. The diagonal seals assume a V-shaped configuration when the bag is filled. '· At 4 is shown a bag bottom. A valve structure is shown at 5 and 6, 5 being the outer portion of the valve and 6 the inner portion of the valve. It is to be noted that the two portions of the valve overlap at their inner extremities. The two valve · portions are sealed to the front and back panels along seals 3 and In Figure 3 is shown a section through a valve of the configuration of that illustrated in Figures 1 and 2. In Figure 4 an extension of thinner gauge film 7 is joined to the inner wall 6 In Figure 5 thinner gauge extensions to both walls of the valve are shown, extension 8 being folded back to lie parallel to the inner side of outer walls. Figure 6 is a sectional view showing the lap sealing of the valve portions 5 and 6 to the front and back panels along seal 9.

The valve bag of this invention is conveniently fabricated from heat-sealable plastic film such as polyethylene . back panels 1 and 2 with a joining gusset fold joining the panels at the position of the bag bottom. Two overlapping pieces of film of shape to form the valve 5 and 6 are then sealed to the front and back panels along diagonal gusset seals 3 and transverse seals 9. The transverse seals 9 may be of either the lap type as shown in the drawings or of the flange type as employed in seals 2a, 2b .and 3. The longitudinal seals, 2a and 2b and bottom gusset seals 3 are then made to complete the bag structure. Excess film from the gusset seal is severed external to the seal position.

The valve bag of this invention has the advantage that it can be made in a continuous manner from lengths of plastic film employing automatic bag-making machinery. The bag itself is readily filled and in filled configuration is rectangular in shape with attendant advantage in ease of storage.

Claims (7)

30033/ 2

1. In a valve..bag having front and back panels joined along two opposed edges to form a flattened tube, the remaining two opposed edges of the front and back panels being joined to gusseted end panels, the improvement which comprises a valve formed by constructing one of the gusseted end panels in two portions sealed to matching edges of the front and back panels along the opposing longitudinal edges of said end panels, the end panels overlapping at their inner extremities so as to form the internal and external walls of the valve, the inner extreme edge of each portion being free and forming the valve opening, the free extremity of the external valve wall carrying an extension folded back into the valve.

2. An improved valve bag as claimed in Claim 1 wherein the extension of the free extremity of the external valve wall is formed of material that is thinner than the main material of the end panel.

3. An improved valve as claimed in Claim 1 wherein the free extremity of the internal valve wall carries an extension of material that is thinner than the main material of the end panel.

4. Am improved valve bag as claimed in Claim 1 wherein the panels forming the valve are joined to the front and back panels by lap seals.

5. An improved valve bag as claimed, in Claim 1 wherein the bag is constructed of heat-sealable plastic film.

6. An improved valre bag as claimed in Claim 5 wherein the seams of the bag are formed by heat sealing.

7. An improved valve bags as claimed in Claim 5 wherein the bag is made of polyethylene film. AGENTS FOR APPLICANTS