US3358907A

US3358907A - Sewn valve bag with flexible elastic insert

Info

Publication number: US3358907A
Application number: US616031A
Authority: US
Inventors: Howard J Winegard
Original assignee: Union Camp Corp
Current assignee: Union Camp Corp
Priority date: 1967-02-14
Filing date: 1967-02-14
Publication date: 1967-12-19
Anticipated expiration: 1984-12-19

Description

Dec. 19, 1967 H. J. WINEGARD 3,358,907

SEWN VALVE BAG WITH FLEXIBLE ELASTIC INSERT Filed Feb. 14, 1967 ZNVENTOR HOWARD J. WINEGARD BY ATTORNEY United States Patent Oflice 3,358,907 Patented Dec. 19, 1967 3,358,907 SEWN VALVE BAG WITH FLEXIBLE ELASTIC INSERT Howard J. Winegard, Trenton, N.J., assignor to Union Camp Corporation, New York, N.Y., a corporation of Virginia Filed Feb. 14, 1967, Ser. No.*616,031 9 Claims. (Cl. 22962.5)

This invention relates to valve bags which are closed by sewing at both ends except for a filling valve in one corner, and more particularly to a type of bag having a flexible insert in the valve corner through which the bag is filled.

Paper bags having valved filling openings are in common use for packaging bulk material, such as chemicals, cement, fertilizer, grain, feed, flour and the like. Such bags are made of a tough and strong paper or other fibrous material, and usually have walls comprising multi-ply layers of paper to increase their strength. Such bags are filled by inserting a spout through the filling opening and blowing the bulk material therein. When the bag has been filled, the spout is withdrawn and the valve is automatically closed by the pressure of the material in the bag against the valve. Since such valves have a tendency to leak and sift materials, sleeves of flexible or limp paper have been inserted in the valve to make a tighter closure of the filling opening and prevent material from sifting through the valve. Such valve sleeves are usually made of a single sheet of paper folded to form a tube with the opposite sides adhesively secured to the bag. Although such sleeves extending into the valve are an improvement from the standpoin of leakage, the leakage is not entirely prevented. Consequently when more expensive materials are packaged in the bags, the sleeve is made longer and extends outward from the valve. After the bag has been filled, the free or outer end of the sleeve is folded and tucked in between the sleeve and valve flap to provide an additional closure to prevent the material in the bag from seeping out. It is diflicult to securely tuck in the end of the sleeve so that it will not be released during the transit of the filled bag. Consequently such tuck-in sleeves has to be carefully and manually tucked in by the workman who operates the filling machine, all of which substantially reduces the speed and increases the cost of filling the bags.

In order to provide a bag having the required strength to resist rupture during handling, many bags are being made with multi-ply walls. Such a bag comprises a plurality of separate sheets positioned one inside the other and may have as many as six plies or layers of paper or a combination of paper and plastic. The multi-ply walls have a substantial thickness that greatly reduces their flexibility. Furthermore, when the end of the bag is folded to form the valve opening, the overlapping folds still further increase the thickness and decrease the ability of the wall to flex, as well as forming irregular surfaces which are to be secured to each other in closing the bag, particularly at the valve end. As a result, a bag having a multi-ply wall and a multi-ply valve is more apt to sift material therefrom and the probability of leakage increases as the wall thickness increases.

In my copending application Ser. No. 568,607, now Patent No. 3,318,511, I have described and claimed a pasted valve bag with a flexible insert. The present application covers a sewn valve bag with a similar insert.

An object is to provide a bag which has a valve that does not appreciably increase the thickness of the wall and does not decrease the walls flexibility.

Another object is to provide a bag which has a standardized valve insert that flexes to accept filling spouts of varying dimension.

Another object is to provide a bag which has a flexible valve insert that returns to its original size upon removal of the filling nozzle.

Another object is to provide a bag which has a flexible valve insert that provides a seal around the filling nozzle.

Another object is to provide a bag which has a flexible valve insert made of elastic sheet material, such as rubber latex, milled rubber, polyvinylchloride, polyurethane, styrene-butadiene copolymer, or similar material.

Another object is to provide a bag which has a flexible valve insert which is of simple and compact construction, economical to manufacture, and reliable in operation.

Still another object is to provide a bag which has a flexible valve insert that is especially effective in preventing fine materials from sifting from the bag.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises an article of manufacture possessing the features, properties, and the relation of elements which will be exemplified in the article hereinafter described and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

FIG. 1 is a perspective View of the corner of a bag with the corner turned in for forming a valve of conventional construction;

FIG. 2 is a plan view of a flexible valve insert made from a laminated or coated sheet;

FIG. 3 is a plan view of a flexible valve insert made from two paper sheets and an elastic sheet;

FIG. 4 is a plan view of a flexible valve insert similar to that of FIG. 3 with the elastic sheet extended beyond the supporting paper sheets;

FIG. 5 is a side view of the bag corner of FIG. 1 with the insert of FIG. 2 placed in the valve;

FIG. 6 is a side view of the corner of FIG. 5 with the bottom of the insert folded and the tape and stitching applied;

FIG. 7 is a side view of the corner of FIG. 1 with the insert of FIG. 4 placed in the valve and the tape and stitching applied.

Referring to FIG. 1 of the drawings, there is shown the corner of a bag 10, preferably formed of a heavy grade of kraft paper. It can also be constructed from heavier or lighter material, depending on the requirements of the 'bag. As shown, the bag has opposed

side walls

12 and 13, with a conventional valve corner having a valve flap 11 which has been turned inwardly about diagonal fold lines 14 and 15. The bag shown is of the type having gussets at its sides as at 16, but it will be understood that the invention is applicable to so-called flat or non-gusseted bags.

FIG. 2 shows a valve insert made up of an elastic sheet 17 lightly laminated or coated to a paper sheet 18. This composite sheet has a fold line 19 in the center for centering the stretchable opening 20 in the valve. The composite sheet is of a size to completely fill the valve opening and prevent leakage between the insert and the valve. The composite sheet in inserted in the valve and secured by adhesive 21 to the sides of the flap, as shown in FIG. 5. The closing of the bag is completed by folding a tape 22 over the end of the bag and sewing such tape and the end of the bag with a line of stitching 23 as shown in FIG. 6. When the filling spout is inserted in the stretchable opening 20 the paper will tear but the elastic sheet will stretch to the size of the opening. After the spout is removed the opening 20 returns to its original dimension. The opening 20 is shown as a circle, but it may have any curvilinear contour, such as an oval, or may be slit having non-tearing ends.

Although it is not necessary, it has been found that leakage along the bottom of the valve flap is further prevented if the insert is folded over along the line 24 before insertion in the valve as shown in FIG. 6.

The valve insert shown in FIGS. 3 and 4 comprises an elastic sheet 17 secured to two sheets of paper 25. The elastic sheet has the stretchable opening 20 centrally located. Such insert is folded along the line 19 and inserted in the valve in the same manner as the laminated or coated insert described above. The paper sheets 25 are secured by adhesive 21 to the sides of the flap, as shown in FIG. 7. In similar manner the end of the bag is closed with a tape 22 and a line of stitching The elastic sheet 17 shown in FIG. 3 is cut flush with the paper sheets 25. Again it has been found that leakage is further prevented along the bottom of the valve flap if the elastic sheet is made slightly longer than the paper sheets, as shown in FIG. 4. In such case the elastic sheet is folded over along a line 26 flush with the bottom edges of the sheets 25 before insertion in the valve, as shown in FIG. 7.

In the construction illustrated in FIGS. 3 and 4 it will be apparent that the sheets 25 primarily serve to permit insertion of the elastic sheet in the valve and to hold such sheet after it is inserted. It would be quite difficult because of the softness and limpness of the elastic sheet to handle it during insertion in the valve. If that problem could be overcome, the elastic sheet alone would sufiice. Accordingly, the construction illustrated in FIG. 2 allows easy handling of the elastic sheet and saves the cost of combining the elastic sheet and the two sheets of paper as heretofore described.

For the insert of FIG. 2 I have found that an elastic sheet of styrene-butadiene copolymer is quite satisfactory and can either be laminated or coated on the supporting paper sheet 18. For the insert of FIGS. 3 and 4 I have found that an elastic sheet of rubber latex of approximately five mils is quite satisfactory. However, it should be clearly understood that the same material could be used in either insert. Any material that is strong enough to withstand tearing when the filling spout is inserted in opening 20 and sufiiciently elastic to have relatively full recovery to its original size when the spout is removed can be utilized. The suitability of the material depends primarily on its extensibility and recovery.

In operation, a filling spout is inserted between the paper sheets secured to the sides of the valve flap and through the stretchable opening 20 in the elastic sheet 17. Material is passed through the spout which is in communication with the inside of the bag. When the bag is filled and the filling spout is removed, the stretchable valve opening 20 returns to its original dimension and the material in the bag thrusts against the interior of the flap 11, causing the inner portions of the valve insert to come into sealing engagement. Due to the fact that an elastic material has a natural tendency to cling to itself. when the filled bag leaves the filling machine, the material and trapped air in the bag will cause the valve to cling even tighter.

Since certain changes may be made in the, above article, and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description (or shown in the accompanying drawing) shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my inventiomwhat I claim as new and desire to secure by Letters Patent is:

1. A sewn valve bag having its corner turned inwardly to form a valve with an inwardly directed valve flap, an elastic valve insert secured to the sides of said valve flap and extending from the bottom to the top of the flap, said elastic valve insert having a stretchable opening in communication with the interior of said bag for receiving a filling spout.

2. A sewn valve bag in accordance with claim 1 in which the elastic valve insert is rubber latex.

3. A sewn valve bag in accordance with claim 1 in which the elastic valve insert comprises styrene-butadiene copolymer mounted on a paper sheet.

4. A sewn valve bag in accordance with claim 1 in which the opening in the elastic valve insert has a curvilinear contour.

5. A sewn valve bag in accordance with claim 1 in which the elastic valve insert comprises an elastic material secured on opposite ends to paper sheets which are secured to the sides of said valve flap.

6. A sewn valve bag in accordance with claim 1 in which the elastic valve insert is mounted on a sheet of paper secured to the sides of said valve flap.

7. A sewn valve bag in accordance with claim 1 in which the walls are multi-ply.

8. A sewn valve bag in accordance with claim 5 in which the elastic material is secured to the paper sheets by a fusion bond.

9. A sewn valve bag in accordance with claim 1 in which the elastic valve insert is secured to said flap by an adhesive.

References Cited UNITED STATES PATENTS 3,065,899 11/1962 Means et al 229-625 3,167,241 l/l965 Woener 229-625 2,751,142 6/1956 Williams et al 299-625 DAVID M. BOCKENEK, Primary Examiner.

Claims

1. A SEWN VALVE BAG HAVING ITS CORNER TURNED INWARDLY TO FORM A VALVE WITH AN INWARDLY DIRECTED VALVE FLAP, AN ELASTIC VALVE INSERT SECURD TO THE SIDES OF SAID VALVE FLAP AND EXTENDING FROM THE BOTTOM TO THE TO OF THE FLAP, SAID ELASTIC VALVE INSERT HAVING A STRETCHABLE OPENING IN COMMUNICATION WITH THE INTERIOR OF SAID BAG FOR RECEIVING A FILLING-SPOUT.