US2511303A - Window bag and method and apparatus for making same - Google Patents

Description

June 3, 50 H. w. STEVENS EIAL 2,511,303

WINDOW BAG AND METHOD AND APPARATUS FOR MAKING SAME Filed Sept. 9, 1946 2 Sheets-Sheet 1 FIG. 2

Laoumo R. HECKER HENRY W. STEVENS IN VEN TOR.

June 50 H. w. STEVENS EI'AL 2,511,303

WINDOW BAG AND METHOD AND APPARATUS FOR MAKING SAME Filed Sept. 9, 1946 2 SheetsSheet 2 LEONARD R HEC E HENRY W. STEVENS INVENTOR.

Patented June 13, 1950 WINDOW BAG AND METHOD AND APPARATUS FOR MAKING SAME Henry W. Stevens, Phoenixville, and Leonard R. Becker, Havel-town, Pa., assignors to Benj. C. Betner Company, Devon, Pa., a corporation of Delaware Application September 9, 1946, Serial No. 695,662

3 Claims.

This invention relates to the art of makin bags, such as those of paper or similar materials. More particularly, it contemplates improvements in machines and processes for forming a multiply material particularly adapted for the manufacture of so-called window bags, that is, bags formed of opaque material but provided with a side opening or window of transparent material, through which the contents of the filled ba may be viewed.

One of the difficulties with window bags made by known methods is that it is very diflficult to positively secure the panel of transparent material in place relative to the opening in the bag wall, so that leakage of the contents from the bag or leakage of foreign matter into the bag, has been prevalent. Also, the known methods of manufacturing such bags are relatively slow and hence expensive, due in part to the necessity for accurate registration of the transparent panel and the opening in the bag wall.

Our invention provides a process and a machine which are capable of forming a multi-ply material which, when operated upon by a bag machine of ordinary type, will enable the manufacture of window bags free from the objections noted above. Further, the manufacture of such bags can be carried on at greatly reduced cost, due to the high speed at which the multi-ply material can be made.

We contemplate that the product of our improved machine and process may be led directly to any ordinary type of bag machine for immediate fabrication into window bags as a continuous process, but we are aware that the multiply material could be stored as such for use in making bags at a later time or at a different location.

Our invention will best be understood by reference to the attached drawings, wherein Fig. 1 is a perspective, diagrammatic view of one form of machine for carrying out our invention;

Fig. 2 is a view, also in perspective, of a portion of a multi-ply web made by the machine of Fig. 1;

Fig. 3 is a. view similar to Fig. 1 of a modified arrangement of a machine for making this type of material;

Fig. 4 is a perspective view of a portion of a web made by the machine of Fig. 3;

Fig. 4a is a view similar to Fig. 4 but showing an alternative form of multi-ply web; and

Fig. 5 is a diagrammatic perspective view of one type of window bag which can be fabricated from the web materials shown.

In general, our improved process for forming window bag material comprises the steps of feeding two webs of suitable bag material, such as paper, glassine or the like, in face to face contact, die cutting the desired window aperture in both webs as a unit, separating the webs for travel along spaced paths, and then directing the webs so as to return once again to closely spaced paths. The separation of the paths of the webs after they have been pierced provides space therebetween for a supply of the transparent window material in strip form, and for means to feed such material in sandwiched relation to the other webs at the point at which they reconvene. Means are provided for applying a suitable adhesive to one or more of the webs to maintain them in contact, it being understood that the lengths of the paths over which the respective outer webs travel while they are separated are either equal, or differ by a multiple of the web length required for one bag. This is necessary to ensure that the window openings in the two outer layers are substantially in register when the piles are secured together.

Referring now to the drawings, in Fig. 1 there is diagrammatically shown a machine in accordance with our invention, two webs of paper It, I2 being drawn from supply reels M, It and caused to travel in juxtaposed relation by pairs of guide rollers i8, 20 and 22, 24. The span of the two webs between these sets of rollers is periodically cut, as by a die cutting roll 26 having a suitably shaped punch portion 28 operating against a backing roller 30, as is well known in the' art.

The two webs Ill, l2 leaving the set of rollers 22, 24 are caused to separate by being led over guide rolls 32, 34, and thence to drive rolls 36, 38, the latter being driven by any desired source of power, such as a motor, not shown.

The path lengths of the respective webs from rolls 22, 24 to rolls 36, 38, are shown in Fig. 1 as being equal, to provide registry between the apertures in such webs, but as noted above, the path lengths may differ by any distance which will not interfere with such registry.

.A sheet of transparent material 44, which may be regenerated cellulose or any other suitable material, is fed between webs Ill and i2 at the rolls 35, 38, such sheet being drawn from a supply roll 46. A suitable pattern of adhesive is applied to web l2 by a coating roll 5|] having spaced adhesive-printing bands 50 fed from a transfer roll 52 which in turn receives adhesive from a supply roll 56 arranged to dip into a tank 58 containing the adhesive liquid. This arrange- 'ment causes a pair of spaced bands I! of adhesive to be printed on web I2, one band on either side of the apertures II in such web.

A similar adhesive printing arrangement is provided to print adhesive upon the under side of web III, such arrangement comprising a coating roll II having bands similar to bands ll of roll II. The bands of roll II, however, are shown as additionally provided with a cross bar BI which operates to print upon web II a series of cross bands of adhesive 86 (Fig. 2), so spaced as to lie close to the leading and trailing edges respectively of the apertures I! in web II.

As best seen in Fig. 2, the resulting laminated product of the machine shown in Fig. 1 comprises upper and lower outer layers I l and I2, both being apertured by windows 80, with a layer 44 of transparent material therebetween, such material being secured to web I2 by the bands I! of adhesive on that web, and to web II by the bands of adhesive 64 on the under side of the latter. The cross bands 6 of adhesive on web II serve to seal layer 44 to web II around all four sides of apertures 68, and hence create a very positive and leakproof seal. We have shown the bands 82 in Fig. 2 so located as to overlap the edges of web 44, whence such bands not only secure web 44 to web I2, but also operate to secure web I2 to web III. However, bands 62 may be located so as to be entirely covered by web 44, in

which case other and conventional means may be utilized to secure layers I. and I! to one another at points not separated by web 44.

We have found it to be advantageous to use as the adhesive for securing together the various plies, a permanently plastic or tacky non-drying adhesive, of which the prior art aflords many examples. Since, in general, the material forming the transparent windows has different P y ical properties from that forming the outer plies, a rigid lamination thereof would give rise to buckling of the transparent window portion whenever differential expansion or contraction occurred. The use of a non-drying adhesive permits suincient slight movement between the piles to overcome this difliculty, whether due to thermal expansion, diiferential absorption of moisture or other causes.

It is clear that many other patterns of adhesive may be applied to the webs II and I2, and that adhesive may also or alternatively be applied to portions of web 44, in order to achieve the desired results. We. therefore, do not wish to be limited to the particular patterns shown in the drawings. The essential requirement is that whatever paste patterns are applied to the webs are adequate to insure that the window material is securely fastened to one or both of the other plies.

The composite web 60 resulting from the operation of the parts described may be reeled up by any suitable and well known mechanism for transport or storage. However, we prefer to operate our machine directly in conjunction with a conventional bag machine, not shown, the material being tubed, folded and subjected to the other known operations of bag-making to produce finished window bags at high speed and with maximum economy. In the latter case, the feed rolls l6, ll of Fig. 1 may be, in fact, the web driving rolls of a conventional bag machine. In any erencs to the top and bottom of the bag. Also, in the event that the outer ply of the bag is to bear printed matter, it is necessary that the conventional compensator of the bag machine control the feed through the apparatus disclosed herein. Such synchronizing arrangements are well known in the art and we have therefore deemed it unnecessary to show them in this application.

It will be observed that the use of a strip of window material between two plies of other material in accordance with our invention results in numerous advantages, both from the point of view of production and in the structure of the bags made therefrom. Conventional window bags which have a discrete window panel secured to the inside of a single ply of bag material are difficult to manufacture, since the handling of the window elements is complicated, and problems of obtaining correct placing ofthe elements over the window apertures are quite troublesome. More important, such prior art constructions are subject to leakage and sifting of the contents around the edges of the window, because of the diillculty of obtaining a perfect seal of the window material to the bag material. Our construction provides a double lap joint between the window ply and the outer and inner plies, which makes perfect sealing very easy to accomplish.

Another important advantage of our invention lies in the fact that window bags can be constructed in which the inner ply or liner can be chosen for mardmum compatibility with the contents of the bag, while at the same time the outer ply may be of a diiferent material chosen for strength, printability or other features. For example, the inner ply may be of greaseproof paper,

glassine, waxed P per or similar material, while the outer ply may be of kraft or other high strength paper, or it may be any material now used in fabricating bags. In other words, the invention provides maximum flexibility of bag design, while actually simplifying the manufacturing operations in comparison with the making of prior art single ply window bags.

Additionally, where the transparent layer is composed of a material, such as thin regenerated cellulose, which has adequate bursting strength but is only slightly resistant to tearing inwardly from edge cracks, the use of a layer of other material on both sides of the transparent portion operates to prevent the starting of such edge cracks. Hence the effective over-all strength of the bag is considerably greater than would result. say, if the transparent layer were merely on the inside of a composite web of two-ply paper.

In Fig. 3 we have shown a somewhat simplified form of machine, which prints adhesive bands only upon the inner or transparent ply of material. This machine comprises supply rolls from which are drawn webs I II, I I! of paper or similar material, and a die-cutting roll I26, having punch element I28 and backing roll I to perforate the two webs with the window apertures I. The outer webs are guided over rollers I32, I34, I10 and Ill, and thence between drive rolls Ill, I42. The transparent web I is fed from supply roll I under a coating roll I" having two adhesive printing bands I50, the latter receiving adhesive from a tank I ll via transfer rolls I and I52, similar to those described above in connection with Fig. 1.

As shown in Fig. 4, the composite material I" resulting from the operation of the arrangements shown in Fig. 3 comprises the outer layers III and I22, provided with windows I68, and the transparent web I44 is secured by the adhesive stripes I62 onlyto web IIII.

A variant of the composite webs described above is illustrated in Fig. 4a, which shows a composite web I60 comprising outer layers III! and II! havingwindow apertures I68 therein. The transparent layer I44 is secured to both webs by bands I62 of adhesive on the upper side of web 2', and bands I64 of under side of web I I.

In both machines described above, it will be understood that the drive rolls (36, 38 of Fig. 1 and I40, I42 of Fig. 3) not only act to' pull the materials through the machines, but they exert sufflciellt pressure thereon to cause the laminae to be permanently secured to one another in the areas at which adhesive was applied.

Fig. of the drawings shows, by way of example only, one type of window bag which may readily and rapidly be fabricated from materials produced in accordance with our invention. In this figure, the bag 200 is formed by tubing the material 60 shown in Fig. 2 so that layer I2 of the material forms the outside of the ba with window 68 being'located as desired in one of the wide panels on what may be the front side of the bag. It will be appreciated that the size of the window apertures shown in Figs. 2, 4 and 4a are somewhat exaggerated for clarity, since to form a gusseted bag of the type shown in Fig. 5, the amount of material extending from the window to each edge of the composite web would have to be greater than as shown. Also, it is to be understood that the window apertures need not be located on the longitudinal center lines of the webs, since if the bag to be formed is of the side seam type, the window apertures would be substantially nearer one edge of the composite webs than the other.

It will be seen from the above description that we have provided an improved method and apparatus, which, when used in connection with conventional bag making machinery, enables the manufacture of window bags in a continuous manner at a much higher speed than heretofore and hence at a reduced cost due to the saving of machine time. It will also be noted that this process and apparatus are extremely flexible in that changes in size or location of the window relative to the finished bag can be accomplished with a minimum of effort and in a short time, thus reducing the idle time of our apparatus as well as of the associated bag machine.

Bags fabricated from the composite material produced in accordance with our invention are superior in strength and leak-proofness to conventional bags having discrete window panels, and the number of imperfect bags which must be rejected, and which represent a total loss to the manufacturer, is greatly reduced. While suitable transparent materials are relatively expensive compared to the material, such as paper, which comprises most of the :bag body, we have found that the savings resulting from the advantages pointed out above more than offset the cost of using a continuous strip of the transparent material. Hence, bags made in accordance with our invention can actually be produced at a lower cost than bags of comparable sizes and materials as made by conventional systems. Moreover, our invention makes it practicable to fabricate, at high speed, window bags having two main plies chosen to have the characteristics desired respectively in an outer layer and an inadhesive on the her liner, with the resulting advantages pointed out above.

Having described our invention in accordancewith the patent statutes, we wish it to be understood that the specific means and steps recited herein are illustrative only, and that our inven tion is not restricted thereto except insofar as required by the scope of the appended claims.

We claim:

1. In a web handling apparatus, means for continuously feeding a pair of webs synchronously along juxtaposed paths, means adjacent said paths for die-cutting both of said webs to form corresponding apertures therein, means for separating said webs, after being cut, for

2. In a web handling apparatus, means for continuously feeding a pair of webs synchronously along juxtaposed paths, means adjacent said paths for die-cutting both of said webs to form corresponding apertures therein, means for separating said webs, after being cut, for travel along spaced paths, means for returning said webs to juxtaposed relation with their corresponding apertures in substantial register, means for continuously feeding a third web between said juxtaposed webs, means for applying an adhesive to at least a portion of one of said three webs on a surface facing another of said webs, and means for pressing said three webs together to cause them to adhere to one another, said third web feeding means being located between the spaced paths taken by said first named pair of webs.

' 3. The process of fabricating a multi-ply web of window bag material, comprising continuously feeding a pair of relatively opaque webs along juxtaposed paths, die-cutting spaced registering apertures in both of said opaque webs, directing said webs along spaced paths, continuously feeding a strip of relatively transparent material along a path between said spaced paths, applying a non-drying adhesive in-longitudinal bands along one of said webs adjacent the apertures therein, and applying pressure to said webs to secure them together and to said strip, with the material of the strip overlying the apertures in said webs.

HENRY W. STEVENS. LEONARD R. BECKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,983,323 Stokes Dec, 4, 1934 2,077,535 Smith Apr. 20, 1937 2,237,346 Gilfillan Apr. 8, 1941 2,284,872 Jaeger et al. June 2, 1942 l 2,312,280 Avery Feb. 23, 1943 2,336,449 Haslacher et a1. Dec. 7, 1943 2,381,605 Leander Aug. 7. 1945 2,384,768 Rau Sept. 11, 1945

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