FI69804C - VALVE AV PLAST ELLER PLASTIC BACKLET PAPPER OCH DESS FRAMSTAELLNINGSFOERFARANDE - Google Patents

Description

1 69804

Valve of plastic or plastic - coated paper and its method of manufacture

The present invention relates to the actual valve of a valve bag made of plastic or paper, wherein the tubular valve is made of plastic or plastic-coated paper and the valve according to the invention is provided with a plurality of slots in the valve wall to make the valve leak-proof.

The invention also relates to the manufacture of the valve and its placement.

The obvious problem is that the valve in the valve bags is not tight. When the bag is placed downwards, this causes the product in the bag to leak out through the valve 15. The leak can be so significant that it causes a significant defect in the product and also uncleanness around the bags.

The leakage problem is obvious precisely if the substance in the bag is dry and in addition easily movable (spherical particles) or if the substance is a granular material which leaks out very easily.

Various attempts have long been made to eliminate this, and several more or less acceptable solutions have been found in this connection.

For example, DE Patent Application No. 1,918,652 filed mentions the use of mascara valves and also a solution to the leakage problem by turning part of the turn back to the valve 180 °. In addition, the valve should have a transverse gap approximately as long as the outer diameter of the fill tube.

The use of lash valves has been generally known for some time, with the lashes being located in the innermost part of the valve, i.e. in the part of the valve furthest inside the bag.

35 The advantage of this valve design is that when the filling pipe is pulled out when the filling is completed, the lashes retract slightly 2 69804 with the filling pipe and mix with each other due to the pressure of the substance. This will prevent the product from leaking.

It could be said that this method has effectively solved the problem of leakage during storage of the products, 5 and therefore it would not be necessary to continue to address this problem.

However, the disadvantage of the method is that it is effective for paper valves, but not for valves made of plastic or plastic-coated paper. This 10 will be explained in more detail.

If the same lash valve principle is used in connection with plastic valves, the disadvantage of the lashes is that they do not settle in the valve in the same advantageous way as in paper valves, and the tightness then becomes incomplete.

Attempts have been made to make plastic valves out of a stronger foil without a satisfactory result. Attempts have also been made to use thinner foil, but this has also failed. As an experiment, attempts have been made to use valves in which the lashes were 20 wider or narrower, longer or shorter, but this too has not given the desired result. The problem of product leakage has clearly not been solved by these measures.

However, according to the present invention, it has become apparent that if the valve lashes are not cut all the way, but if a small edge holding the lashes together is left on the inner edge of the valve, this solves the leakage problem. Thus, it could be said that the valve has changed from a lash valve to a longitudinal slot valve, where the earlier lashes form strips of valve material.

This longitudinal groove structure, where the lashes terminate at a small edge at the inner edge of the valve, has been found to effectively limit product leakage. The design also has the advantage that it can be manufactured as a continuous process and simplifies the manufacture and placement of the valve turn in the bag during the manufacturing process.

3 69804

The invention is according to the appended claims.

For a further description of the invention, reference is made to Figure 1, in which Figure 1 shows a top view of a flat-pressed tubular lash valve characterized in that the lashes are cut all the way, while Figure 2 shows a longitudinal section, a flat-pressed and tubular biscuit seen from above. -10, with a small edge left on the inner edge of the valve to hold the "lashes" together. These "lashes" are hereinafter referred to as strips.

Fig. 3 shows the position of the valve in the bag, the valve, since it is inside the bag and not visible from the outside, being drawn in broken lines. Slots 6 are also drawn in broken lines.

Fig. 1 shows a lash valve of a known construction in which a paper valve wall 1 is cut at one end in the longitudinal direction so as to have a formed lash section with hanging loose lashes 2. The lashes are separated by cutting and the cut 3 forms a separating part between the lashes. The lashes are attached at their rear end to valve 1.

As already mentioned, Fig. 2 shows a valve made of plastic or plastic-coated paper according to the invention, comprising strips 5 and in which the strips 5 remain together at both ends of the valve wall 1. The valve wall 1 and its strips 5 form a certain entity and are referred to herein as a valve. The valve forms a tube obtained by extruding or gluing or welding a flat foil of plastic or plastic-coated paper from adjacent ends of the foil in the longitudinal direction of the foil.

The wall thickness of the foil is preferably 80-120 u, but 35 it may be thicker or thinner.

4 69804

The width of the strips is more or less optional, but usually it depends on the width of the bottom of the bag, so that the narrower the bottom of the bag, the narrower the strips are and vice versa. Usually the strips have a width of 5-15 mm, but they can also be narrower or wider. The strips 5 are at their rear end a continuous part of the valve wall 1, which is divided by slots 5. At the front end, the strips are held together by an edge 7, which also forms part of the valve wall.

The function of this edge 7 is to hold the strips 5 together and then to prevent them from being pulled back separately into the valve when the filling pipe is pulled out after filling. In order to fulfill its function, the edge 7 must have a certain tensile strength so that it has a size-15 va effect with respect to the strips 5. In practice, it has been found that an edge about 2 mm wide is sufficient to achieve the desired effect. However, the edge width may be slightly larger for thinner foils or slightly smaller for stronger foils.

Figure 3 shows a bag 8 with a folded and lit-20 tea-pressed base part 9. This part of the bag is already known and does not belong to the invention. Valve 1 is shown by a broken line, glued fixedly under the cross-layers of the bag and completely covered by an outer layer made of plastic foil or plastic-coated paper 25 10.

With the aid of the described valve, a leak-proof bag structure has been obtained.

However, the concept of the invention has not caused any changes in current equipment or working methods, as the vent-30 brick and its strips are manufactured continuously with the same equipment as before and then attached to the bag as a continuous operation.

Claims (4)

5 69804 A tubular valve for a plastic or paper bag, the valve being made of plastic foil or plastic-5 coated paper and comprising a plurality of slots in the longitudinal direction of the valve, characterized in that the slits (6) are delimited on both sides by a valve wall (1) ) ends in front of the slits at the edge (7). Valve according to Claim 1, characterized in that the width of the edge (7) is 1 to 7 mm, most preferably 1.5 to 3.0 mm. Valve according to Claim 1, characterized in that the slits are 20 to 100 mm long, most preferably 30 to 60 mm. A method of manufacturing a tubular valve of plastic or plastic-coated paper according to claims 1, 2 and 3, characterized in that in the continuous process the valve is divided into slots of suitable length, preferably 30-60 mm long, with roller blades or repetitive fixed blades, and furthermore, that the slits terminate in the edge (7) of the valve wall (1), the width of the edge (7) being about 1-7 mm, most preferably 1.5-3.0 mm, and that the valve is then moved to the other end of the bag 25 and fixed in such a way that the free part comprising the valve strips (5) remains inside the bag without touching the fastener.