US3249287A - Thermoplastic valved bags - Google Patents

Description

y 1966 Q 0. D. RHODES 3,249,287

THERMOPLASTIC VALVED BAGS Filed Oct. 21, 1963 2 Sheets-Sheet 1 CHESTER D. RHODES INVENTOR.

I BY fa qw ATTORNEY.

May 3, 1966 c. D. RHODES THERMOPLASTIC VALVED BAGS 2 Sheets-Sheet 2 Filed Oct. 21, 1963 C H E S T E R D. R H O D E S INVENTOR.

UM I ATTORNEY.

United States Patent 3,249,287 THERMOPLASTIC VALVED BAGS Chester D. Rhodes, Wilbraham, Mass., assignor to Monsanto Company, a corporation of Delaware Filed Oct. 21, 1963, Ser. No. 317,505 2 Claims. (Cl. 22962.5)

The present invention relates to novel bags and to methods for preparing same.

In my copending application Serial No. 259,708 filed February 19, 1963, a novel valve thermoplastic bag is described wherein a plurality of valve sleeve members are fusion sealed to a corner portion of a tubular thermoplastic bag blank. This copending application was filed as a continuation-in-part of a now issued United States Patent No. 3,087,670 which describes a thermoplastic bag having a unitary valve sleeve member. The bags described in the specification and drawings of the patent and the copending application are non-gusseted. It has been found that these bags can be further improved by gusseting the bag both with respect toopening and closing the valve as well as in palletizing or stacking of same.

Accordingly, it is a primary object of the present invention to provide novel gusseted self-closing valve bags of substantial volumetric capacity which are fabricated from thermoplastic materials and methods for .preparing same.

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

These and other objects are attained in a valve bag comprising, in combination, a gusseted tubular body of thermoplastic film that is sealed across its top with a top corner of said tubular body being folded into the bag and constituting a valve flap, and one or more valve sleeve members of thermoplastic film which are sealed at one end to the valve flap and at a lengthwise portion thereof partially across the top of the bag.

Other objects and advantages of the invention will be apparent from the following detailed description when read in conjunction with the attached drawings in which: FIG.-I is an elevation of a blank from which the valved bag is to be prepared;

FIG. II is an elevation of a blank which has been gusseted from which the valved bag is to be prepared;

FIG. III is an elevation of an alternate embodiment of a blank from which the valve bag is to be prepared illustrating a plurality-,of-v'alvemembers;

FIG. IV is a fragmentary front view of the sealed valve bag illustrating the valve mouth or opening;

FIG. V is a fragmentary perspective side view of the sealed valve bag illustrated in FIG. IV with parts broken away; and

FIG. VI is a fragmentary perspective side view of an alternate embodiment of a valve bag with parts broken away illustrating a tri'angularly cut valve sleeve member.

Referring to FIG. I, the numeral designates a tube of thermoplastic film which has a top peripheral edge 12 and a valve sleeve member 14 in the form of a sheet or film of thermoplastic material which is of subtantially thinner gauge than the body of the tube 10. The valve sleeve member 14 is fusion sealed to a corner portion of the tube 10 at the line of seal 16. This particular drawing shows the valve sleeve member 14 sealed to the inner side of the corner portion of tube 10. This corner portion of tube 10 will eventually be folded into the tube and is destined to become the valve flap in the finished 'bag. Prior to folding this corner in, however, the tube and valve member are gusseted as illustrated in FIG. II. For the purposes of this invention, it is not important whether the valve member 14 is adhered to tube 10 before the tube is gusseted or whether the tube is gusseted first before the valve sleeve is adhered or fused in place. It

3,249,287 Patented May 3, 1966 ice is, however, important that the valve sleeve member 14 be of substantially thinner gauge than the body of the tube 10 in order to obtain the desired closure effect after filling. In addition, it is sometimes desirable to employ more than one valve sleeve member such as illustrated in the alternate embodiment of FIG. III. Although it is highly important that substantially thinner gauge material be used as the valve members in all instances, the various types of materials which are packaged will generally determine whether one or more sleeve members are more desirable. With particular reference to FIG. III where more than one valve sleeve member is employed, it is generally preferred to form the sleeves of unequal length with the longest sleeve, that is the one that extends the furthest across the top width of the bag, being of the thinnest gauge. A more detailed description of the manner by which a plurality of valve sleeves are attached to a tubular bag blank may be had by reference to my copending United States application S.N. 259,708 filed February 19, 1963.

Referring to FIG. II, a gusseted tube of thermoplastic material is shown having a valve sleeve member 14 FIG. II is folded into the bag creating a fold line at ap proximately the dashed line 18. FIGS. IV and V illustrate the bag blank after the fold has been completed and after fusion sealing the top of the bag along dashed line 20. As may be seen in FIGS. II and IV, the top edge 22 of the valve sleeve member which is in a generally horizontal position in FIG. II is shown in FIG. V in a generally vertical position. It will be noted in FIG. IV that the terminal end 24 of the top seal 20 extends to the left of seal 16 which is employed to join the valve sleeve member to the corner portion of the tube blank 10. This is done to prevent leakage and to improve the strength and durability of the valve.

In general, the valve sleeve will be fabricated from 0.5 to 4 mils and more preferably from 1-2 mil film which will be membrane-like in effect whereas the body of the tube will be fabricated from 4 to 15 and more preferably 512 mil film.

The gusseted thermoplastic valve bags of the present invention may be prepared by affixing or sealing at least one valve sleeve member to a corner portion of an openend tubular bag blank. To form the valve, the corner portion must be folded down into the bag to-form a valve flap. The valve sleeve member may be ailixed or sealed to this corner portion either before or after the valve flap is formed. In any event, the valve member is afiixed to the valve flap such that the projecting edges of the valve sleeve member are positioned within and in juxtapositioned parallel relationship with the open edges of the end of the tubular blank. The open end is closed and sealed across its entire length including the edges of the valve sleeve member therebetween. The preferred sealing means are heating elements designed to fuse the plastic layers together.

The manner by which the valve bags are filled may be described with reference to FIG. IV. When the bag is filled, the contents of the bag will press the valve sleeve member against the top seal portion of the tube to elfect a closure. This is a somewhat different closure effect than is obtained in the non-gusseted valve sleeve bag wherein the valve is more apt to be forced laterally against one side of the bag. In the non-gusseted bags, the effectiveness of the closure against leakage when the bags are laterally stacked will depend to a large extent on whether the valve sleeve member is forced under or over the contained material wherein the tendency towards leakage is greatly increased. Whether the valve sleeve member of the non-gusseted bags is forced upwardly or downwardly by the contained material will, of course, depend on the rather random manner in which the bag is handled. With the gusseted bag, however, the valve sleeve member tends to be forced against the top seal of the bag regardless of handling. In other words, when the bags are stacked on their sides in the normal manner, the contained material tends to flow against the top seal of the bag thereby pressing the valve sleeve member against the top seal thereby effecting a tighter closure. Consequently, improved closure effects are obtained by use of the gusseted bag as opposed to the nongusseted thermoplastic bags. In addition, as previously indicated, the closure effects can sometimes be improved by utilizing a plurality of valve sleeve members.

In FIG. IV, the valve sleeve is shown in a general rectangular folded shape. However, it is possible to vary this shape by slanting the valve member edge 22 downwardly at various angles away from the normal. In addition, it is sometimes desirable, as shown in FIG. VI, to slant one of the edges of the valve sleeve membet to form a triangle with an apex 26 to obtain a stronger and more uniform seal along the top of the bag.

The valved thermoplastic bags can be fabricated from such fusion scalable plastic materials as polyethylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, polyisobutylene, polypropylene, polytetrafluoroethylene and the like.

The preferred material of construction is polyethylene, a solid, tough polymer of ethylene which can be manufactured in film-form in thicknesses less than one mil. It is light in weight, extremely low in water absorption and moisture permeability and consequently is an excellent material for packaging uses. In addition layers of polyethylene can be heat sealed or fused together to present a strong bond. It is also preferable to utilize the same material for the construction of both the bag and the various sleeve members since optimum fusion of two or more layers of film can only be accomplished if the fusion temperatures of the various joining layers are approximately within the same temperature range.

The valved bags of this invention ordinarily will have a substantial volumetric capacity, e.g., at least 1 cubic foot, and are designed primarily to carry from about 50 to about 100 pounds of such common pulverulent materials such as cement, flour, fertilizer, carbon black, chemicals and granular materials such as salt, sugar and the like. The walls of the bag ordinarily will have a thickness of the order of 415 mils, although obviously the walls may be either thinner or thicker as indicated by the use to which the bags are to be put. Ifdesired, the walls of the bag can be fabricated from a plurality of plies of thin thermoplastic film. The valve sleeve member or members ordinarily will be thinner than the walls of the bag. If more than one sleeve member is used, the longest sleeve member will generally be fabricated from film which is about .5 to 4 mils thick depending on the strength and flexibility of the material, and in the case of polyethylene, thicknesses of 1-2 mils are generally sufficient to effect a membrane-like flexibility in the material.

The above descriptions and particularly the drawings are set forth for purposes of illustration only. Many variations and modifications thereof will be obvious to those skilled in the art and can be made without departing from the spirit and scope of the invention herein described.

What is claimed is:

1. A valve bag comprising, in combination, a gusseted tubular body of thermoplastic film that is sealed across its top, a top corner of said tubular body being folded into the bag and constituting a valve flap and at least two valve sleeve members of thermoplastic film which is sealed at one end to the valve flap and at a lengthwise portion thereof partially across the top of the bag; the thermoplastic film of at least one valve sleeve member being of substantially thinner gauge than the thermoplastic film of the tubular bag body and extending the furthest across the top of the bag.

2. The valve bag according to claim 1 .wherein the tubular body and at least one valve sleeve member are polyethylene.

References Cited by the Examiner UNITED STATES PATENTS 2,392,094 l/1946 Lee 9335 2,542,170 2/1951 Weeks.

2,660,100 11/1953 Doyle 9335 2,804,257 8/ 1957 Hasler et al 22962.5

2,959,343 11/ 1960 Rosander 22962.5

3,004,698 10/1961 Ashton 22962.5

3,040,967 6/1962 Klein M 229-62.5

3,080,102 3/1963 Ottinger 22962.5

3,087,670 4/ 1963 Rhodes 22962.5

JOSEPH R. LECLAIR, Primary Examiner.

FRANKLIN T. GARRETT, Examiner.

D. M. BOCKENEK, Assistant Examiner.

Claims (1)

1. A VALVE BAG COMPRISING, IN COMBINATION, A GUSSETED TUBULAR BODY OF THERMOPLASTIC FILM THAT IS SEALED ACROSS ITS TOP, A TOP CORNER OF SAID TUBULAR BODY BEING FOLDED INTO THE BAG AND CONSTITUTING A VALVE FLAP AND AT LEAST TWO VALVE SLEEVE MEMBERS OF THERMOPLASTIC FILM WHICH IS SEALED AT ONE END TO THE VALVE FLAP AND AT A LENGTHWISE PORTION THEREOF PARTIALLY ACROSS THE TOP OF THE BAG; THE THERMOPLASTIC FILM OF AT LEAST ONE VALVE SLEEVE MEMBER BEING OF SUBSTANTIALLY THINNER GAUGE THAN THE THERMOPLASTIC FILM OF THE TUBULAR BAG BODY AND EXTENDING THE FURTHEST ACROSS THE TOP OF THE BAG.

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