VALVE OF PLASTIC OR PLASTIC COATED PAPER AND THE METHOD OF PRODUCING SAME

Abstract: Valve bags to be used as packing for powdery substances, where the valve for the filling of the material into the bag is of plastic coated paper. The invention also concerns the method of producing the valve. For quite some time consumers have felt it as a drawback that ordinary valves have not been tight or spillfree. The problem was solved by cutting slits (6) in the tube shaped valve wall (1) of plastic or plastic coated paper with roller knives or repetitive fixed knives. These slits may be from 20 to 100 mm long. The slits terminate in a narrow brim (7) which constitutes part of the tube wall (1). Thereby narrow strips (5) of the plastic wall (1) will emerge between the slits. The advantage of the said design, unlike known fringe valves, is that the fringes are held together by means of a narrow brim (7) and can thus be retracted collectively into the valve when the filler spout is withdrawn from the valve after the filling is completed.

Description: Valve of plastic or plastic coated paper and the method of producing same The present invention concerns the actual valve of a valve bag of plastic or paper where the tube shaped valve is made from plastic or from plastic coated paper and the valve according to the invention is fitted with a number of slits in the valve wall in order to make the valve spillfree. The invention also concerns the production of the valve and the positioning of it- It is an express problem that the valve in valve bags is not tight. When the bag is put down, this will result in some of the goods in the bag being spilled through the valve. The spill can be so considerable as to cause a noticeable shortage of goods and also a mess around the bags. The spill problem is particularly evident if the substance in the bag is dry and in addition is easily movable (spherical particles) or if the substance is a granulate which is par¬ ticularly easily spilled. 0MP1 Through the ages various attempts have been made to remedy this, and in this connection several more or less acceptable solutions have been found. West German application No. 1,918,652 laid open for in¬ spection, for instance, mentions the use of fringe valves and also a solution to the spill problem by turning part of the cuff back into the valve by 180°. Further, the valve should have a transversal slit which is approximately as long as the outer diameter of the filler spout. The use of fringe valves has been well known for some time, where the fringes are located on the innermost part of the valve, i.e. that part of the valve which is the farthest in¬ side the bag. The advantage of this valve design is that when the filler spout is retracted after the filling is completed, the fringes will be pulled back a little with the filler spout and will become intertangled due to the pressure of the sub¬ stance. This will stop the spill of the goods. It could be said that this measure has solved the spill problem during storage of the goods effectively, and accordingly that it would not be necessary to continue work on this problem. The measure has, however, the disadvantage that it is efficient for valves of paper but not for valves of plastic or plastic coated paper. This will be explained further. If the same fringe valve principle is used in connection with plastic valves, the fringes have the disadvantage that they do not settle in the valve in the same favourable manner as for paper valves, and thereby the tightening becomes in¬ complete. Attempts have been made to make plastic valves from a thicker foil without a satisfactory result. It has been attempted to use thinner foil, but this has not been successful either. As an experiment attempts have been made to use valves in which the fringes were wider or narrower, longer or shorter, but even this has not given the desired result. The problem of spill of the goods has evidently not found a solution through these steps. However, according to the present invention, it has become evident that if the fringes of the valve are not slit all the way, but a small brim which keeps the fringes together is left at the innermost rim of the valve, this will solve the spill problem. Accordingly, it could be said that the valve has changed from being a fringe valve to becoming a length¬ wise slit valve in which the previous fringes form strips of the valve material. This design with lengthwise slits and where the fringes end in a small brim at the innermost rim of the valve, has proved to limit the spill of the goods effectively. The design also has the advantage of being produced in a continuous process and it simplifies the production of the valve cuff and the fitting into the bag during the production process. The invention is according to the following claims. For further explanation of the invention, reference is made to Fig. 1 in which Figure 1 shows a flattened, tube shaped fringe valve viewed from above, in which the characterizing feature is that the fringes are slit all the way, while Figure 2 shows a lengthwise slit, flattened and tube shaped valve according to the invention, viewed from above, O...PI in which a small brim is left at the innermost rim of the valve which keeps the "fringes" together. These "fringes" will in the following be referred to as strips. Figure 3 shows the position of the valve in the bag where the valve, because it is located inside the bag and not visible from the outside, is drawn by dot-and-dash lines. The slits (6) are also drawn by dot-and-dash lines. Figure 1 shows a fringe valve of a known design in which the valve wall ( 1 ) of paper at one end is slit lengthwise in such a way as to form a fringe part with hanging loose fringes (2). The fringes are divided from each other by the slitting, and the cut (3) forms the separation between the fringes. The fringes (2) are fastened at their rear end to the valve (1 ) . As previously mentioned. Figure 2 shows a valve of plastic or plastic coated paper according to the invention which con¬ sists of strips (5), where the strips (5) are held together at both ends of the valve wall (1). The valve wall (1) with its strips (5) constitute an entity and is here referred to as the valve. The valve forms a pipe or a tube which is the result of ex¬ truding or gluing or welding of a plane foil of plastic or of plastic coated paper across the adjoining ends of the foil in the longitudinal direction of the foil. The wall thickness of the foil is preferably in the range of from 80 to 120 u, but it may be thicker or thinner. The width of the strips will be more or less optional, but as a rule it will depend on the width of the bottom of the bag in such a way that the narrower the bottom of the bag is, the narrower will the strips be, and vice versa. Usually, the width of the strips will be in the range of from 5 to 15 mm, but they may also be narrower or wider. The strips (5) are at their rear end a continuous part of the valve wall (1), divided by slits (6). At their forward end the strips are held together by means of a rim (7) which also constitutes part of the valve wall. The object of this rim (7) is to hold the strips (5) toget¬ her, and thereby to prevent them from being pulled back separately into the valve when the filler spout is retracted after the filling is completed. In order to serve its pur¬ pose, the rim (7) must have a certain tensile strength so that it has a gathering effect on the strips (5). In prac¬ tice it has proved that a rim width of approx. 2 mm is suf¬ ficient to achieve the " desired effect. The rim width may, however, be somewhat larger for thinner foils or somewhat smaller for thicker foils. Figure 3 shows the bag (8) with it ' s folded and flattened bottom section (9). This part of the bag is known and is not part of the invention. The valve (1) is shown by a dot-and- dash line glued firmly below the intersecting layers of the bag and entirely covered by an outer layer of plastic foil or foil of plastic coated paper (10). By the described valve a spillfree bag design has been achieved. The inventive conception has, moreover, not led to any changes in the existing equipment or in the work procedures, as the valve with its strips is produced continuously in the n same equipment as before and is fitted into the bag in a sub¬ sequent continuous operation. -BTTREA

Claims: Claims A tube shaped valve for a bag of plastic or paper where the valve is of plastic foil or plastic coated paper and has a number of slits in the longitudinal direction of the valve, c h a r a c t e r i z e d i n t h a t the slits are limited to both sides by the valve wall ( 1 ) , but in such a manner that the valve wall (1) at the forward side of the slits ends in a brim (7) . Valve acccording to claim 1 , c h a r a c t e r i z e d i n t h a t the brim (7) has a width of from 1 to 7 mm, but is preferably between 1,5 and 3,0 mm wide. Valve according to claim 1 , c h a r a c t e r i z e d i n t h a t the slits are between 20 and 100 mm long, but preferably have a length of from 30 to 60 mm. Method of producing a tube shaped valve of plastic or plastic coated paper according to claims 1, 2 and 3, c h a r a c t e r i z e d i n t h a t in a continuous processe the valve is divided into slits of suitable length, preferably from 30 to 60 mm long by means of roller knives or fixed knives with a repetitive movement and furthermore, that the slits end in a brim (7) of the valve wall (1) " where the brim (7) has a width of somewhere between 1 and 7 mm, but is preferably between 1,5 and 3,0 mm wide, and that the valve is subsequently passed across one end of the bag and attached there in such a way that the free section with the valve strips (5) remains inside the bag untouched by the attaching medium.

Inventors: BJOERKE HANS, BOGEN ODDVAR, BJOERKE, HANS, BOGEN, ODDVAR
Applicants: NORSK HYDRO AS, NORSK HYDRO A.S
Application year: 1983
Main classification: B65D30
IPC codes: B65D30