US 2996238 A
Descripción (El texto procesado por OCR puede contener errores)
Aug. 15, 1961 R. E. LINDE 2,996,238
PASTED CONTAINER Filed Nov. 12, 1957 INVENTOR. ROBERT E. LIN DE TTORNEY .nited This invention relates to fibrous containers such as bags; sacks, or cartons made of paper or the like, the seams and folded bottom portions of which are secured by pasting. More specifically, the invention relates to such containers which are required to have a special protective coating included in their construction because of the nature of the materials to be packaged therein.
In particular, this present invention relates to bags used for the packaging of tacky materials, such as certain waxes, synthetic and natural rubbers, asphalts, etc. In this particular use it is necessary, in order that the bags can be removed cleanly and quickly from the packaged tacky material when desired, that the inside of the bags have a coating of a suitable release compound such, for example, as polyethylene, clay with a binder, silicone, or some other equally satisfactory release coating, acting to protect the paper or bag material from direct contact with the packaged tacky product. Consequently, bags employed for this packaging are customarily made from paper one face of which (or one face of the inside ply in the case of multi-ply bags) has first been treated with such a release coating.
However, a well known problem is encountered in the manufacture of bags from such coated paper, since, when the side seams and bottom are closed by the usual process ofpasting, a satisfactory bond is not obtained due to the fact that it is diflicult to adhere such coated paper surfaces to each other or to adhere such coated surface to an uncoated surface. As a result, failures along the pasted seams and bottoms of bags made from coated papers are a common occurrence.
Although some special adhesives have been developed to meet this problem in bag pasting, and these special adhesives, due to some interaction with the coating substances, succeed to some extent in penetrating through the coating to the surface of the paper, thus making a better bond, the results are not entirely reliable, and furthermore such special adhesives are so expensive, by comparison with the adhesives ordinarily used in bag manufacture, that they have not come into general use.
Other attempts to meet the same problem have included the use of heat sealing means, but such process has. been found to be very expensive and far from foolproof.
The object of the present invention is to provide an improved container, made from coated paper and the like, and an improved method of making such containers, wherein conventional adhesives can be used for the pasting of the seams and bottoms but in which the resulting bond produced by the ordinary adhesive will be just as satisfactory as in the case of containers made from entirely uncoated paper.
In brief, this object is attained in a simple, practical and inexpensive manner by mechanically scufling off or abrading portions of the coating on the paper surface Where the pasting is to take place so that the resulting disrupting of the coating at such locations will expose the paper fiber in preparation for the application of the paste or adhesive.
The manner in which and the means by which this object isaccomplished, and the advantages of the improved bag produced in this Way, will be readily understood and appreciated from the following brief description with reference to the accompanying drawings.
tes Patent ice In the drawings:
FIGURE 1 is a schematic perspective view ofpart of a coatedstrip of paper from which bags are to be made in accordance with this invention, showing portions of the coating on the paper being scuffed ofi prior to the forming of the coated paper into the bag tubing;
FIGURE 2 is a diagrammatic side view illustrating the operation of the scuffing rolls on the coated paper as it is being fed into the bag machine;
FIGURE 3 is a more or less diagrammatic plan view illustrating the scufling and the forming of the bag tube in the first steps of the bag making process; and
FIGURE 4 is a plan view of a severed section of the bag tube, being formed into a single bag, showing the bottom folds ready for the completion of the bottom closure.
In the following description, it is assumed, for simplicity, that the bag to be made is a single ply bag, thus formed from a single sheet of paper, with one faceof the paper (becoming the inside face of the bag) coated with a desired releasing coating. It is to be understood, however, that the invention may also be used withmultiply bags in which the inner ply is formed from such coated paper.
Referring first to FIGURE 1, the paper web from which the bag tubing is to be formed prior to the cutting of the tubing into the lengths for the individual bags is indicated by the reference 10 and the release coating or film which has been applied over one entire face of the paper web is indicated by the reference character 11'. It is assumed in FIGURES l, 2 and 3 that the coated web 10 is travelling from right to-left on its way into the bag forming machine.
The dried coating film 1 1 is scuffed off or abraded'in'a continuous narrow strip 12 along one edge of the coated web by a narrow scuffing roll 13 rotating against the direction of 'web travel, the roll 13 being rotated constantly inthe direction indicated in FIGURE 1 by any suitable means (not shown). When the coated web is formed into the bag tubing this marginal scuffed-off strip 12 is caused to overlie the edge portion of the outer or uncoated face of the opposite side of the web as presently mentioned.
A pair of identical, axially aligned and spaced scuffing rolls 14, 14 (FIGURE 1), positioned at opposite sides of the travelling paper web, and also rotating against the direction of web travel, being rotated by suitable means (not shown), are periodically moved into contact with the travelling web for a brief moment each time, and during the moments of contact with the web this pair of rolls scuffs the coating off in a pair of substantially rectangular areas such as those indicated at 15, 1'5i'n FIGURE 1. As later explained, these scuffed-on areas 15, 15 occur at locations corresponding to part of the bottom pasted portions of the successive bags to be formed in the bag machine, and consequently the movement of the rolls 14, 14' into contact with the paper web is properly timed and synchronized with the travel of the paper web (by means not shown) so that such contact occurs once for each of the sections into which the subsequently formed bag tubing is cut for the individual bags.
Referring now to FIGURE 2, which illustrates diagrammatically the travel of the coated web past the scufiing rolls and into the bag tube-forming portion of the bag machine, the coated paper web 10 (with the coated face uppermost) is shown as being drawn (from right to left) past a series of guide rolls 16 while being constantly contacted by the scufling roll 13 along one edge, and also being intermittently contacted by the previously mentioned pair of transversely aligned scuffing rolls, one of which is indicated at 14 in FIGURE To provide for the desired intermittent contact of the rolls 14, 14' with the travelling web the rolls may be secured on a common driven shaft, which shaft is supported in a pair of pivoted arms, one of such arms being indicated at 17 in FIGURE 2, with each of these arms riding on a rotating cam 18. The web then passes into the tubeforming portion of the bag machine during which stage a longitudinal edge of the web moves past a paste-applying roll 19. The means through which the folding of the Web into the bag tubing takes place and the manner in which the paste is applied for the longitudinal seam of the bag tubing is conventional and since this is old and well known it need not be described, and constitutes no part of the present invention. In FIGURE 3, the travelling paper web is shown in plan view as it leaves the pair of scuffing rolls 14, 14 and proceeds to be formed into bag tubing. It will be noted that the edge of the web from which the coating has been scuffed off along the marginal border 12, as previously described, is folded over so as to overlie the edge portion (indicated at in FIGURE 3) of the uncoated face of the web. Before the scuffed border portion 12 is brought into superimposed position on the opposite edge portion 10' a layer of paste 20 is applied along the latter edge portion by the paste-applying roll 19, the pasteapplying roll being in constant engagement with the adjacent edge of the web and being constantly supplied with paste in the customary manner (not shown). Consequently when the paste is applied on the edge of the uncoated face and the scuffed-off marginal portion 12 is superimposed on the paste layer 20, the resulting bond along the bag tube seam will be as strong and effective as in the case of bags made from entirely uncoated paper.
In the forming of paper bags on customary bag machines, the bag tubing, after being formed, is automatically cut into bag lengths by a cutter knife or other suitable cutter means, whereupon the folding of the bottom portion of each successive bag length takes place. In the device illustrated for carrying out the present invention the means by which the scufiing rolls 14, 14' are intermittently caused to contact the travelling paper web (thus, for example, the rotating earns 18, as indicated in FIG- URE 2, which raise and lower the arms 17 on which the shaft for the rolls 14, 14' is mounted), and the cutoff knife (not shown) for the paper tubing are properly timed and synchronized so that they operate at the same regular intervals, and also are so set that the severing of each bag length from the bag tubing occurs at the beginning of the scuffed portions 15, and thus occurs subsequently along the broken lines indicated at 21 in FIG- URE 3. Consequently the scuffed-off portions .15, 15 in each severed bag length will then be in the end of the bag length Where the bottom of the bag is to be formed. FIGURE 4 shows such a severed bag length with the bottom slitted and given the first folding step in the forming of the customary bottom for a well-known selfopening or rectangular bottomed type of bag. From FIGURES 3 and 4 it will be apparent that, upon the forming of the bag tubing, the scuffed-01f portions 15, 15 will be brought together in one of the bottom flaps 22. With the bottom portion of the bag so arranged the paste is then applied in the customary U-shaped path indicated at 24. Thus the paste is applied across the flap 22 from which the coating on the paper web has been scuffed off, and also on the uncoated faces of the adjacent bottom portions. The bag bottom is thereupn completed in the usual manner by folding first the flap 23 and adjacent portion over on the crease line indicated at 25, and finally folding the flap 22 and adjacent portion over on the fold line 26, thus bringing the flap 22 on the outside of the bag bottom and covering a portion of the underlying flap 23. As apparent, with this arrangement the pasting of the bottom closure takes place only between the uncoated surface portion of the paper andbetween the uncoated and scuffed-off surface portions.
Various types of scuffing or abrading means may be used in the carrying out of the invention. A preferred type would be a roll having a surfacing of such material as Carborundum cloth. To prevent the abrasive surface of the rolls from becoming clogged from continuous use, brushes can be installed adjacent the rolls, as indicated at 27 in FIGURE 2, and the coating particles as removed can be carried off through a vacuum suction tube, as indicated at 28 in FIGURE 2. Rotating wire brushes might also be used for the scufiing.
Any adhesive normally applied in pasting scams or bottoms in uncoated paper bags may be employed for bonding the abraded portions of bags in accordance with the present invention. Suitable adhesives may comprise polyvinyl acetate or dextrin as the essential constituents thereof.
The following examples are merely illustrative of the present invention and it will be understood that the invention is not limited thereto.
Example 1 Kraft paper of 60 lbs. per ream basis weight and having on one side thereof a 2.5 lbs. per ream dry silicone coating was employed for conversion into bags. The portions of the coated paper which were to be pasted to form the bag bottom and longitudinal seam were abraded by means of Carborundum surfaced rolls. The abraded areas of the paper were then pasted with a dextrin-type adhesive and bonded to the uncoated portion of the paper in the customary manner. The resulting bonds between the pasted surfaces were as strong as those achieved between the same paper without the silicone coating using the same type and amount of the adhesive. On the other hand, the hereinabove described silicone-coated paper pasted with the same adhesive failed to produce a bond between the coated and uncoated surface thereof.
Example 2 Kraft paper of 60 lbs, per ream basis weight and having on one side thereof a 20 lbs. per ream dry polyethylene coating was treated in substantially the same manner as in Example '1, however a wire brush was employed as the abrading means, and a polyvinyl acetate type adhesive was employed for pasting. The strength of the resulting bonds between the scuffed-off areas and uncoated paper was essentially the same as that obtained in Example 1.
It will be understood that this method can be employed similarly in the making of other types or shapes of coated paper bags, such as satchel-bottom or diamond-shaped bottom bags, other square type bags, etc., and also, as previously mentioned, in making multiply bags with the coating on the inside ply. The present method may be applied also in the making of other types of containers made from fibrous materials, such as cartons, the inner surface of which bears a release coating of the character described hereinabove wherein, for example, a coated corner seam or closure is to be pasted to a coated and abraded or an uncoated area of the container. In the manufacture of multi-ply bags requiring resistance to moisture, vapor, chemicals, etc., the coated ply may constitute and ply in the bag construction, depending on the ultimate use for such bag. It is essential only that the coated surface be scuffed off where necessary to accommodate the bonding adhesive, but also necessary that the scuffed-off portions be carefully restricted so that they will be completely covered and will not be exposed at any point in the finished bag.
1. An improved pasted fibrous container for packaging of wax, rubber, asphalt and the like tacky materials, the outer face of said container being uncoated and the inner face of said container having a release coating, said container having a pasted longitudinal seam and a pasted bottom closure, said inner face having scuffed-off portions of said coating in said longitudinal seam and in Said bottom closure, said inner face being pasted to the uncoated outer face of said container at said longitudinal seam and at said bottom closure, whereby the pasted bond is substantially as strong as if the same pasted container had no release coating on the inner face thereof. 2. An improved pasted releasable paper bag including a sheet of paper coated on one face with a release coating, said face of said sheet constituting the entire side face of the bag, said bag having a pasted longitudinal seam and a pasted bottom closure, and said face of said sheet having scuiTed-oif portions of said coating in said longitudinal seam and in said bottom closure, said inside face of said bag being pasted to the uncoated outside face of said bag at said longitudinal seam and at said bottom closure without failure of the bond in the pasted areas.
References Cited in the file of this patent UNITED STATES PATENTS Diem Mar. 26, Gulick Mar. 25, Gaylord July 21, Bergstein Apr. 11, Vogt Sept. 5, Fluckiger Dec. 3, Wagner Jan. 18, Bennett Apr. 24, Stem Mar. 15, Hayward et a1. Dec. 16,
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