US3281060A - Valve bag - Google Patents

Description

Oct. 25, 1966 M J. HEIMOS ETAL 3,281,060

VALVE BAG Filed Sept. 22, 1964 2 Sheets-Sheet l Oct. 25, 1966 M. J. HEIMOS ETAL VALVE BAG 2 Sheets-Sheet 2 Filed Sept. 22. 1964 bql United States Patent 3,281,060 VALVE BAG Milton J. Heimos, Minneapolis, and Avron A. Snabb, St.

Paul, Minn., assignors to Bemis Company, Inc., a corporation of Missouri Filed-Sept. 22, 1964, Ser. No. 398,316 14 Claims. (Cl. 229-62.5)

Among the several objects of the invention may be noted the provision of a valve bag, and particularly a heavy duty valve bag, made of heat-scalable sheet plastic material (e.g., polyethylene) having a valve flap at one corner and a valve sleeve extending into the bag from the valve flap, in which the sleeve is also made of heatsealable plastic sheet material (e.g., polyethylene) and heat-sealed to the valve flap; the provision of valve bag such as described so constructed as inherently to tend to stretch the sleeve fiat for tight sealing against leakage upon filling the bag; the provision of a valve bag such as described which has strong heat-sealed tape end closures; and the provision of a valve bag such as described as to which seals are made in the region of the valve without blocking of the valve sleeve. Other objects and features will be in part apparent and in part pointed out hereinafter.

' The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which one of the various possible embodiments of the invention is illustrated,

FIG. 1 is a view in elevation of one face of a flat plasticbag tube from which a bag of this invention is made;

FIG. 2 is a view in elevation of the other face of the tube;

FIGS. 3 and 4 are enlarged transverse sections taken on lines 3-3 and 4--4 of FIG. 1, respectively, thicknesses being exaggerated and these sections being partly broken away;

FIG. 5 is a view of one face of a valve sleeve which is assembled with the tube shown in FIGS. 1-4;

FIG. 6 is a section of the sleeve taken on line 6-6 of FIG. 5;

FIG. 7 is a view showing the upper end of the tube opened up for the formation of a valve flap and the application thereto of the valve sleeve;

FIG. 8 is a view corresponding to FIG. 7 showing the sleeve applied to the valve flap;

FIG. 9 is a view in elevation of a completed valve bag, broken away in part; and

FIGS. 10, 11 and 12 are enlarged sections taken on lines 1010, 11-11 and 1212 of FIG. 9, respectively, With thicknesses exaggerated.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring first to FIGS. 1-4 of the drawings, there is shown a flat bag tube 1 made from heat-scalable sheet plastic material, in particular polyethylene. This may be made, for example, by forming a continuous web of polyethylene into flat bag tubing with a back seam and segmenting the web into individual flat bag tubes 1 in conventional manner. One wall of the tube, which may be referred to as its front wall, is designated 3. Its other wall, which may be referred to as its back wall, is designated 5. The back seam of the tube, which is in its back wall 5, appears at 7 in FIGS. 2-4. The side edges of the flat tube are constituted by folds 9 and 11 in the sheet polyethylene. While a seamed tube is shown, it is contemplated that a seamless tube may be used.

In accordance with this invention, the tube 1 is specially prepared with a first area 13 of heat-seal-inhibiting material in the form of a relatively wide band at one cm- 3,281,060 Patented Oct. 25, 1966 ner thereof which is to constitute the valve corner (the upper left corner as shown in FIG. 1) on the inside face of the.tube. This band 13 extends along the inside of the upper margins of the front and back walls from the fold 9 part way across both walls of the tube, and around the fold. Further in accordance with this invention, the tube is specially prepared with a second area 15 of heat-sealinhibiting material in the form of a band at the other corner of the valve end of the tube (the upper right corner as shown in FIG. 1) on the inside face of the tube. This band 15, which may be narrower than band 13, extends along the inside of the upper margin of one Wall of the tube (the front wall 3 as shown) from the fold 11 partway across the tube, and may extend around the fold 11 and a short distance across the back wall 5. Additionally, the tube is prepared with a third area 17 of heat-sealinhibiting material in the form of a band extending completely across the tube on the inside face thereof at the opposite end of the tube (i.e., its lower end as shown in FIGS. 1 and 2). This band 17 is shown as extending completely across the inside of one Wall of the tube (the front wall 3), around folds 9 and 11, and part way across the inside of the other Wall (the back wall 5), although it could extend substantially completely across the back wall 5.

Referring next to FIGS. 5 and 6, there is shown a valve sleeve 19, which consists of a rectangular piece of heatsealable sheet plastic material, in particular polyethylene, having stripes 21 of heat-seal-inhibiting material on one face thereof extending along the side margins of the sleeve from end-to-end thereof.

The heat-seal-inhibiting material used at 13, 15, 17 and 21 may be, for example, a commercially available polyarnide-base ink which is unpigmented so as not to appear through the polyethylene. As noted above, tubes 1 may be made from a continuous web of polyethylene, and this Web may be printed with said heat-seal-inhibiting ink in a suitable pattern to provide bands 13, 15 and 17 when the tubing into which the web is formed is segmented into individual bag tubes such as the tube 1. Sleeves 19 may be formed by applying continuous stripes of the 'heat-seal-inhibiting ink to a continuous strip of polyethylene, and segmenting the printed strip into individual sleeves.

As appears in FIG. 7, the valve end (the upper end) of the tube 1 is opened up by folding open the upper portion of one wall of the tube (the front wall 3 as shown) on a fold line 23 extending transversely across the tube spaced from the upper end of the tube. This results in the formation of triangular flaps 25 and 27 at opposite corners of the valve end of the tube. The flap 25 at the lefthand corner as shown in FIG. 7, which constitutes the valve flap of the bag to be formed, has the band 13 of heat-seal-inhibiting material on the inside face thereof along its inner edge 29.

As appears in FIG. 8, the sleeve 19 is applied to the opened-up end of the tube with the outer end portion of the sleeve overlying the inner margin of the valve flap 25, with the sleeve extending inward beyond the inner edge 29 of the valve flap, and with the stripes 21 of heat-sealinhibiting material on the sleeve face up. With the sleeve lying flat on the opened-up end of the tube and positioned thereon as stated, the sleeve is heat-sealed to the valve flap 25 along two lines of seal 31 and 33 extending parallel to the inner edge 29 of the valve flap, the line of seal 31 lying closely adjacent the inner edge 29 of the valve flap and the line of seal 33 lying adjacent the outer end of the sleeve. It is also heat-sealed to the front and back walls (and further heat-sealed to the valve flap) along two lines of seal each designated 35 extending lengthwise of the sleeve (i.e., transversely of the tube). This sealing is accomplished as by applying heated heat-sealing bars to tube reverts to its original condition.

'along these lines. 15 prevents heat-sealing together of the walls 3 and 5 the exposed face of the sleeve along lines 31, 33 and 35 and applying suitable pressure, with the opened-up end of the tube backed in any suitable way. The heat-sealinhibiting material at 13 You the inside of the valve flap (which is interposed between the valve flap and the walls of the bag) prevents sealing of the valve flap to the walls I of the tube, except along portions 35a of lines 35 which cross the valve flap and along portions 31a of line 31 which lie later-ally outward of lines 35. In this regard,

Band 13 preferably has a total length (cross-wise of the triangular valve'flap 25) approximating one-half the length of the inner edge 29 of the valve flap 29, and preferably slightly less than one-half the length of edge 29. That is,- each half of the band 13 extending from fold9 has a length approximating one-half the length'of edge 29.

'Thus, considering the condition in which the valve flap 29 is opened up as shown in FIG. 7 and sleeve 19 is applied thereover as shown in FIG. 8, the ends 13a of band 13 are located approximately half way between the longithe sleeve, preferably being spaced inward from the side edges of the sleeve a distance slightly greater than onei than one-quarter the length of the inner edge 29 of the valve flap 25. Portions 35a of lines 35 are located slightothercorner-of the tube at said one end of the tube, i.e.,

ly outward of ends 13a of band 13, preferably being spaced inward of the side edges of the sleeve a distance slightly less than one-quarter the width of the sleeve.

After the sealing'of the sleeve 19 to the valve flap 25 and to the walls 3 and 5 of the tube as above described, the opened-up portion of the front wall 3 is folded back on the upper portion of the back wall 5. In the course of this folding back of the opened-up portion of the front wall, the valve sleeve 19 is folded in'half on itslongitudinal center, line 39 in FIGS. 5 and 8-11 and the valve flap 25 is folded in half on its longitudinal center line -indicated at 41 in FIGS. 7-10. However, flap 27 is opened up flat so that the upper right-hand corner of the The width of the sleeve is such that its sides reach generally to'the upper end edge of the tube. 7

Then, the upper end of the tube is provided-with a closure by folding a length of heat-scalable tape 43, in particular a polyethylene tape, around the end of the tube,

1 and applying heat and pressure to the associated tube and tape to effect heat-sealing of one side 43a of the folded tape to the outside of wall 3 all along a seal 45 extending throughout the width of the upper end of the tube, and heat-"sealing of the other side 43b of the folded tape all along a seal 47 extending throughout the width of the upper end of the tube. While the walls of the tube become heat-sealed to the respective halves of the sleeve 19 along the lines 43:: and 43b, the stripes 21 of heat-sealinhibiting material at the side margins of the sleeve prevent heat-sealing together of the halves of the sleeve The' 'heat-seal-inhibiting material at along the line of the seals at 45 and 47 all the way from the inner end of the sleeve to the right-hand side edge' 11 of the tube. Thus the walls of the tube and the two halves of the sleeve are free of one another throughout the width of the upper end of the tube.

The lower end of the tube is closed by folding a length .of heat-sealable plastic tape 49, in particular a polyethylene tape, around the lower end of the tube and applying heat and pressure along a line 51 within the confines of band 17 of heat-seal-inhibiting material to effect heatsealing of one side'of the tape 49 to wall 3 and the other side of the tape 49 to wall 5 without any heat-sealing totudinal center line 39 of the sleeve and the side edges of quarter the width of the sleeve and hence slightly greater 7 bag may be carried out by means of a conventional band sealer. It may be desirable to use thicker tape at 43 than at 49 since the thickness at various regions along seal 47 is greater than along seal 51, and thicker tape may be needed at 43 to resist higher sealing pressures encountered at these thick regions in passing between the sealing bands. For example, the tape used at 43 may be eight mils thick, compared with five mil tape at 49. Or two layers of five mil tape may be used at 43, and one at 49.

As will be seen, the completed bag comprises the flat tube 1 of heat-sealable sheet plastic material (e.g., polyethylene) having valve flap 25 extending inward at the valve corner at one'end (its upper left-hand corner as. illustrated in FIG. 9). 'half on its longitudinal center line:41 and has heat-seal- The valve flap 25 is folded in inhibiting material (e.g., polyamide base ink) coated on its inside face at 13. The valve sleeve 19, made of heatsealable sheet plastic material (e.g., polyethylene), and

' 3of the tube has heat-seal-inhibiting material at 15 on the inside face thereof along the said one end (the upper end) of the tube from the inner end :of the sleeve to the the upper right-hand'corner of the tube as viewed in FIGS. 1 and 9. Tape 43 constitutes a closure for the wake end of the tube, being folded around this end of the tube, with one side 43a of thefolded tape heat-sealed 1 to the outside of wall 3 along line 45 and the other side 4315 of the tape heat-sealed to the outside of wall 5 along line 47 within the confines of the heat-seal-inhibiting a similar closure for the lower end of the tube.

view of the positive inhibition of sealing by the heat-seal- I inhibiting material at 15 and 21, is a strong closure,

stresses incurred on dropping or other rough handling -of the filled bag being taken in shear by the seals 45 and 47. As will be understood, these seals are strongly resistant to separation in shear. Similar considerations apply to the closure constituted by tape 49. Positive elimination of -a face-to-face seal between walls 3 and 5 by means of the heat-seal-inhibiting material at 15, 17 and 21 insures preservation of the strength of the seals at 45, 47 and 51., If there were a face-to-face seal between the walls 3 and 5 along the line of seals 45 and 47 or along the line of seal 51, it would be a weak seal, resisting rupture only by its resistance to peeling apart, and its peel resistance would inherently be low. In this regard,

7 to rupture in shear. The face-to-face seal would tend to .peel apart under stresses incurred on rough handling of the bag, and this would tend to weaken the bag along the line of seals 45 and 47 andthe line of seal at 51.

bag maybe shorter for a given capacity. This is be- -a face-to-face seal between the bag walls along these lines, the capacity of the bag is increased or, conversely, the

cause the tapes 43 and 49 initially form the endclosures at the very ends of the bag tube, rather than face-to-face seals between the bag walls spaced from the ends of the bag tube;

When the opened-up portion of the front wall 3 is folded back on the upper portion of the back wall 5, with resultant folding in half of the valve sleeve 19 on its longitudinal center line 39, as above described, seals 35 become located approximately half way between the resultant folds at 39 and 41 in the sleeve and valve flap and the end of the bag (preferably slightly nearer the end of the bag than the folds at 39 and 41). Thus, these lines 35 lie generally coincident with the lines on which the walls of the bag fold when the bag is filled and the end of the bag squares out. As a result of the two halves of the sleeve being sealed to the walls of the bag along lines 35 at the stated locations, when the top of the bag is squared out (as inherently occurs on filling the bag) the valve sleeve is nicely pulled out fiat by forces transmitted from the bag walls to the sleeve via the seals on lines 35, with attendant tight sealing of the valve sleeve to preclude leakage of the bag contents. The lines of seal 35 extend substantially throughout the length of the sleeve and, in the outer end portion of the sleeve which laps the valve flap, portion 35a thereof seal together the sides of the sleeve, the valve fiap and the walls of the bag. Portions 31a of lines of seal 31, lying outside the confines of area 13 of heat-seal-inhibiting material, secure together the sides of the sleeve and the walls of the bag, but only outward of lines 35.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A valve bag comprising a flat tube of heat-scalable sheet plastic material having front and back walls, said tube having a valve flap extending inward at a valve corner at one end thereof, said valve flap being folded in half on its longitudinal center line, a valve sleeve of heatsealajble sheet plastic material folded in half on its longitudinal center line and having its outer end overlying the valve flap, said sleeve extending inward therefrom into the bag, the sides of the sleeve reaching generally to said one end of the tube, a coating of heat-seal-inhibiting material applied to the inside of the tube in such position as to be interposed between the walls of the tube and the sides of the valve flap, said sleeve at its outer end being heat-sealed to the valve flap in the region of said heatseal-inhibiting material and the valve flap being free of the walls of the tube in said region, and closures for the ends of the tube.

2. A valve bag as set forth in claim 1 wherein the sides of the sleeve are heat-sealed to the inside of the respective walls of the bag along lines of seal extending lengthwise of the sleeve between the longitudinal center line of the sleeve and the side edges of the sleeve.

3. A valve bag as set forth in claim 1 wherein said coating of heat-seal-inhi biting material is located on the inside face of the valve flap on both sides of its longitudinal center line and the sleeve at its outer end is heatsealed to the valve flap on lines of seal extending parallel to the inner edge of the valve flap in the region of said heat-seal-inhibiting material.

4. A valve bag as set forth in claim 3 wherein the sides of the sleeve are heat-sealed to the inside of the respective walls of the bag along lines of seal extending lengthwise of the sleeve generally half way between the longitudinal center line of the sleeve and the side edges of the sleeve.

5. A valve bag comprising a flat tube of heat-sealable sheet plastic material, said tube having a valve flap extending inward at a valve corner at one end thereof, said valve flap being folded in half on its longitudinal center line, said valve flap having heat-seal-inhibiting material on the inside face thereof, a valve sleeve of heat-sealable sheet plastic material folded in half on its longitudinal center line and having its outer end overlying the valve flap, said sleeve extending inward therefrom into the bag, the sides of the sleeve reaching generally to said one end of the tube, said sleeve at its outer end being heat-sealed to the valve flap, at least one side of the said sleeve having a stripe of heat-seal-inhibiting material extending endwise on the inside thereof adjacent its outer longitudinal edge, at least one wall of the tube having heat-seal-inhibiting material on the inside thereof along said one end of the tube from the inner end of the sleeve to the other corner of the tube at said one end of the tube, a closure for said one end of the tube comprising a tape of heat-scalable sheet plastic material folded around said one end of the tube, one side of the folded tape being heat-sealed to the outside of one wall of the tube and the other side of the folded tape being heat-sealed to the outside of the other wall along a line of seal extending across the tube within the confines of the stripe of heat-seal-inhibiting material and the heat-seal-inhibiting material which extends from the inner end of the sleeve to the said other corner of the tube, and a closure for the other end of the tube.

6. A valve bag as set forth in claim 5 wherein at least one wall of the tube has heat-seal-inhibiting material on the inside thereof extending across said one wall at the other end of the tube, and said closure for said other end of the tube comprises a tape of heat-scalable sheet plastic material folded around said other end of the tube, one side of the latter tape being heat-sealed to the outside of one wall of the tube and the other side of the latter tape being heat-sealed to the outside of the other wall of the tube along a line of seal extending across the tube within the confines of the last-mentioned heat-sealinhibiting material.

7. A valve bag as set forth in claim 5 wherein the sides of the sleeve are heat-sealed to the inside of the respective walls of the tube along lines of seal extending lengthwise of the sleeve between the longitudinal center line of the sleeve and the side edges of the sleeve.

8. A valve bag as set forth in claim 7 wherein the lines of seal which secure the sides of the sleeve to the walls of the tube are located generally half way between the longitudinal center line of the sleeve and the side edges of the sleeve.

9. A valve bag as set forth in claim 8 wherein the lines of seal which secure the sides of the sleeve to the walls of the tube extend across the valve flap on opposite sides of the area of the heat-seal-inhibiting material on the inside of the valve flap.

10. A valve bag as set forth in claim 9 wherein the sleeve at its outer end is heat-sealed to the valve flap on lines of seal extending parallel to the inner edge of the valve flap in the region of the heat-seal-inhibitiug material on the inside of the valve flap.

11. A valve bag as set forth in claim 10 wherein at least one wall of the tube has heat-seal-inhibiting material on the inside thereof extending across said one wall at the other end of the tube, and said closure for said other end of the tube comprises a tape of heat-scalable sheet plastic material folded around said other end of the tube, one side of the latter tape being heat-sealed to the outside of one Wall of the tube and the other side of the latter tape being heat-sealed to the outside of the other wall of the tube along a line of seal extending across the tube Within the confines of the last-mentioned heat-seal-inhibiting material.

12. A valve bag comprising a fiat tube of heat-sealable sheet plastic material, said tube having a valve flap extending inward at a valve corner at one end thereof, said valve flap being folded in half on its longitudinal center line, a valve sleeve of heat-sealable sheet plastic material folded in half on its longitudinal center line and having its outer end lapping the valve flap and secured thereto, said sleeve extending inward from the valve flap generally half way between the longitudinal center line of the sleeve and the side edges of the sleeve and closures for the ends of the tube.

. 13. A valve bag as set'forth in claim 12 wherein said 7 lines of seal extend substantially throughout the length of the sleeve and, in the portion of the sleeve lapping the Y valve flap, seal the respective sides of the sleeve, the

valve flap and the walls of the bag together.

14. A valve bag as set forth in claim 13 wherein the outer end' of the sleeve overlies the valve flap.

' References Cited by the Examiner UNITED STATES PATENTS I Burrell 93---35 10 JOSEPH R. LECLAIR, Primary Examiner.

FRANKLIN T. GARRETT, DAVID M.

Rosander 22962.5

Ashton 22962.5

Ottinger 229-62.5 Crawford et a1. 229- 47 Becker 93'35 BOCKENEK,

Examiners.

Claims (1)

1. A VALVE BAG COMPRISING A FLAT TUBE OF HEAT-SEALABLE SHEET PLASTIC MATERIAL HAVING FRONT AND BACK WALLS, SAID TUBE HAVING A VALVE FLAP EXTENDING INWARD AT A VALVE CORNER AT ONE END THEREOF, SAID VALVE FLAP BEING FOLDED IN HALF ON ITS LONGITUDINAL CENTER LINE, A VALVE SLEEVE OF HEATSEALABLE SHEET PLASTIC MATERIAL FOLDED IN HALF ON ITS LONGITUDINAL CENTER LINE AND HAVING ITS OUTER END OVERLYING THE VALVE FLAP, SAID SLEEVE EXTENDING INWARD THEREFROM INTO THE BAG, THE SIDES OF THE SLEEVE REACHING GENERALLY TO SAID ONE END OF THE TUBE, A COATING OF HEAT-SEAL-INHIBITING MATERIAL APPLIED TO THE INSIDE OF THE TUBE IN SUCH POSITION AS TO BE INTERPOSED BETWEEN THE WALLS OF THE TUBE AND THE SIDES OF THE VALVE FLAP, SAID SLEEVE AT ITS OUTER END BEING HEAT-SEALED TO THE VALVE FLAP IN THE REGION OF SAID HEAT SEAL-INHIBITING MATERIAL AND THE VALVE FLAP BEING FREE OF THE WALLS OF THE TUBE IN SAID REGION, AND CLOSURES FOR THE ENDS OF THE TUBE.

Images