US2340546A - Container - Google Patents

Description

Feb: L MM, J. w. MEAKER CONTAINER Filed DEC. l5, 1959 I pmmqamm: am

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, would be inevitable.

' iliade.` heretofore of Patented Feb. 1, 1944 UNITE-D STATES PATENT OFFICE CONTAINER 'John w. Masker, Evanston. nl. Application December 13, 1939, Serial No. 309,044

21 Claims.

This invention relates to bags, envelopes, wrappings, packaging covers or containers, made of paper or like thin, flexible, substantially air impervious sheet material as distinguished, for example from woven fabrics: the term container" being used herein to describe this class of articles generically and the term paper, the type of sheet material, of the character indicated, from which the containers are made.

The container with which the present invention is concerned may be in the class of valve bags, so-called, such for example as shown in United States patent to Bates No. 1,762,292, April 1, 1930, which is typical of a rather large number of bags of this general type: or the containers may be in the class of open mouthed bags; and in either case they may be made of single or multiple ply stock, that is of one or more sheets or envelopes of paper; and in any case they may be made of one or more plies of l paper which have been treated to make it waterproof.

The primary object of the invention, broadly speaking, is to make the bag of paper, or its equivalent, which has been formed artificially, and after the paper has been manufactured, with a relatively large number of very minute perforations made by the action of electric arcs so that the paper, in the formation of the perforations is removed by burning, or other eect of the electric arcs to give clean holes having no burrs. Burrs will iiatten out and to a greater or less extent close the holes when the contents distend the bag or when the bag is under pres- `sure orwhen the plies are rubbed against each other; and in the case of minute perforations, made (if that were practical) by mechanical pin pricking or punching, the formation of burrs Moreover, the punching or pin pricking of perforations in paper necessarily weakens the paper; whereas. in the piercing of the paper with perforations formed by electric arcs, the strength of the paper is not substantially diminished but in some cases appears to be enhanced. As a result of this treatment of the paper (the inherent porosity of method of manufacture, has a loose texture and is, therefore, more or less porous, so that while filling, the air can escape, noti only around the fillingv spout, which is undesirable, but also through the paper itself. However, this type of what might be called inherently, or naturally. or originally (from its method of manufacture) porous paper is more expensive than some other less porous papers, certain'types of kraft wrapping papers, for example, since it has to be made from selected pulp produced from selected woods of more expensive character. These pulps have to be carefully digested and beaten and for longer periods than is the case with other papers, and they must be run through the paper making machine more slowly than is the case with the Rmarijufacture of the cheaper grades of paper; 'thedeslred porosity depending upon the character and proper arrangement in the web of the cellulose fibers. 'I'he difference in price between these inherently porous papers, known of which the required porosity is which, as manufactured, may be substantially nil or may be high, or at any intermediate point), the bags may be given whatever degree of porosity or air perviousness may be required for the purposes for which the bags are used, as well as a uniformI from a given lot of the perforated paper.

' .jFor example, valve bags for cement have been paper which, because of its porosity for all bags made as "cement bag papers, and the ordinary kraft wrapping papers, may be several dollars per ton. Furthermore, the so-called porous papers are not always uniform in their porosity. Frequently they are not and this results in the rejection of some lots for bag making purposes involving, often, quite a loss. The porous papers are likely to be less strong than the cheaper grades of paper, such as some types of kraft or wrapping paper; and they are also usually less water resistant because of the loose structure by means obtained.

For certain other purposes paper bags, Whether valve bags or open mouth bags, should be readily air pervious; for example, to admit air to the contents where such ventilation is necessary to the keeping quality of the contents;

and to allow escape of air to prevent bursting I when the bag is dropped or otherwise roughly handled.

According to this invention, the paper from which the bag is to be made, or the bag itself, after or during the process of being made up, is formed with a ,relatively large number of minute perforations-of the character described, the size and number per unit of area being varied as desired, so that the bag, taking accountv of the original, natural or inherent porosity. 'or absence of porosity, of the paper, may be made as porous and as uniformly porous as required for the purposes for which the bags are to be used, and this without substantially reducing the strength of the paper.

A further object of the invention is to provide l by an apparatus such asis shown a bag or other container. either of the single or multiple ply type, and either of the valved or open mouthed or other type of bag, which shall contain one or more plies of water-proofed or moisture-resistant paper, and. byperforating such ply or plies, make the bag pervious to air without substantially diminishing its waterproof character. This may be accomplished by treating paper of the waterproofed type, paper that has been sized loaded, coated or impregnated with a waterproofing material, for example asphaltum or asphalt compounds and which, be-

cause of its method of manufacture or subsequent treatment, is` substantially impervious to air, -so` as to perforate such paper with holes so small in diameter that, without pressure, water will not penetrate into the bag through them, or to any considerable extent, atmospheric moisture, but which, nevertheless, because of the number of such perforations, will allow egress and ingress l of relatively large quantities of air. The inventesting the porosity of paper) may give as low` a porosity index as 196, seconds, indicating a practically air impervious paper, if perforated according to the present invention may be given any desired degree of porosity, as high, for example,` as 5 seconds, without appreciably aiecting the waterproof character of the paper. That is, the paper may be substantially as waterproof as the original paper and yet will be as porous as will be necessary for use in the making of valve bags, or for other purposes where the heretofore naturally contradictory characteristics of porosity and imperviousness to water may be desirable. In fact, the porosity of the electric arc pierced paper may be greater than the porosity of the inherently porous paper (cement bag paper) without bringing about any substantial diminution of the waterproof characteristics of the electric arc pierced paper.

The densometer referred to above consists of a pair of telescoping cylinders, the inner movable cylinder having an opening covered by the paper tested and being graduated for air volumes of 100 cubic centimeters. The air can escape only through the paper, under pressure of the weight of the inner cylinder, and the number of seconds required for 100 cc. of air to pass through the paper is, therefore, a negative index of porosity. Ordinary so-called porous cement bag paper of 50 pounds per ream, when tested by this machine may have porosities ranging from 20 to 30 seconds.

In the case of the use of perforated waterproof paper in a multiple ply valve bag, it will ordinarily be sufficient to make one ply only of the perforated waterproof paper. The other plies can be advantageously made, in the interest of economy, of naturally porous paper or non-waterproofed paper which has been electrically perforated in accordance with the present invention.

The perforating operation may be performed in United States patent to Irven H. Wilsey No. 1,790,452,

patented January 27, 1931. With this apparatus the paper is moved between spaced electrodes formed, arranged and operated to produce arcs which pass through the paper making minute holes therein. The spacing of the holes may be varied by the design of the electrodes and by the speed of movement of the paper through the machine; and the size of the perforations may be varied to any practical extent by varying the current intensity of the arcs or by other suitable means. Naturally these perforations will be smalll enough, depending upon the character of the material to be packaged,

' to prevent the sifting out of any substantial quantity of material, but sufiiciently large, or at least suillciently numerous, to allow the quick voiding of air when the bag is being filled or. if, after lling, the bag is accidentally dropped. or to make the bag suitable for other Ventilating purposes.

The size of the perforations may vary, for example, from about 1/00 to tiene of an inch in average diameter. The number may vary from ten to one hundred per square inch, more or less. The pattern or spacing of the openings will ordinarily be quite irregular. However, the invention is not liinited to these particulars, which are merely preferential and illustrative. The holes though ysmall are cleancut,A without burrs and tests indicate that they do not materially lessen the strength of the paper as shown, for example, by comparative Mullen tests. Pin pricking the paper, a difcult operation mechanically and one which is not easily susceptible of regulation in respect to the size and number of the holes, would ordinarily involve not only the formation of burrs, which atten out and close the openings but also a, considerable weakening of the structure of the paper. The fact that the electric arc pierced perforations do not appreciably reduce the strength of the bag material, as would be the case with punched or mechanically made holes, is probably due to the fusion or plastlcizing of the material around the perforations so as to hond together, or to therest of the paper, the severed bers giving clean cuts and reinforced edges in distinction to the burred and frayed -edges of pin pricked or other mechanically punched perforations. As a matter of fact the electric arc plercedperforations appear in some cases at least to strengthen rather than weaken the paper.

The invention is illustrated in the acompanying drawing, in which Fig. 1 is a side view of a valve bag of the sewn type;

Figs. 2 and 3 are sectional views, with the scale much enlarged, on lines 2-2and 3-3 of Fig. l, respectively;

Fig. 4 is a very much enlarged view, such as might be seen under a strong microscope (except that the cellulose fibers are not shown) of a small area of the side wall of a bag to illustrate a typical spacing of the perforations; and

Fig. 5 is a section on line 5-5 of Fig. 4.

It is usual to make paper valve bags of several plies. The drawing shows a four ply bag, consisting really of four bags or envelopes, one inside the other. The invention, however, is not limited to any particular number of plies. The bags might b'e made of two, three, four or ilve plies, or even of one ply, although the single ply bags would not be suitable for certain materials. In the case of a multiple ply construction, the bag consists of a plurality of paper tubes, one

members I 8, constituted by 'overlapped and pasted together, preferably, in

staggered relation as indicated I3 (Figs. l'and 3). The upper and lower edges of the paper, that is, the open ends of the tubes, are bound together by binding strips Il, I5 sewn to the paper constituting the body of the bag, by stitching 'I6-I6. At one upper corner of the bag, the material is turned inwardly to form an opening i1, which is closed through pressure of the material, when the bag is illled, by the valve the inturned portions at l0, H, Iland ofthe body.

The invention is not limited to this particular I type of bag which is shown merely for the purpose of illustration.

While the average size of the perforations and average number per unit area, when the perforations are made electrically as above described, may be regulated with considerable accuracy, the relative positions of the perforations will ordinarily notvbe uniform due to the fact that the arcs do not go through the paper in a straight line from one electrode to the other, but appear to be considerably deflected; and this gives a diiferent perforation" of the paper treated and has the advantage that in the case of multiple ply bags the perforations in different plies do not register, as illustrated in Figs. 4 and 5, so that in case the ilnest of the pulverulent material should sift out ot the inner ply it is almost certain to be trapped by the outer ply or plies. f

This application is in part a continuation of, and a substitute for applicants copending application for Perforated paper container," filed January 23, 1939, Serial No. 252,360.

I claim: A

1. An air pervious bag closed except for a relatively small valved lling opening to snugly receiver a filling spout adapted to contain pulverulent material comprising at least one envelope of material which as manufactured is substantially impervious to air but which is provided with a large number of electric arc pierced, burrless perforations minute enough to prevent any substantial amount of pulverulent material fromsifting pattern, in different parts y out of the bag or any substantial amount of moisture from penetrating into the bag therethrough.

while sumcient in number and spaced closely enough together and over a large enough area of the envelope to allow free escape of air from the bag when the bag is illled by the forcing of material through its valved lling opening.

2. An air pervious bag closed except for a relatively small valved iiliing opening to snugly receive a filling spout adapted tov contain pulverulent material comprising at least one envelope of waterproofed material which as manufactured is substantially impervious to air but is provided with a large number of electric arc pierced, burrless perforations minute enough to prevent any substantial amount of pulverulent material from sifting out of the bag or any substantial amount of moisture from penetrating into the bag therethrough, while suiilcient in number and spaced closely enough together and over a large enough area of the envelope to allow free escape of air from the bag when the bag is lled by the forcing of material through its valved filling opening.

3. An air pervious container comprising at least one envelope .of waterproofed material which, as manufactured, is substantially impervious to air, but which is provided with a large number of electric arc pierced, burrless perforabut suicient enough together and over a large enough area of bag therethrough, while suilicient in number and distributed closely enough together and over a large enough area to make said envelope substantially porous in respect to the passage therethrough of air. f

4. An air pervious container comprising at least one envelope` oi' waterproofed material which, as manufactured. is substantially impervious to air, but is` provided, over a major portion of its area, with a large number of electric arc pierced, burrless, perforations minute enough to prevent water, except under pressure, or any substantial amount of atmospheric moisture from penetrating into the bag therethrough, while suf# ficient in number and distributed closely enough together to make said envelope substantially porous in respect to the passage of air therethrough.

5. An air pervious container comprising at least one envelope of waterproofed material which, as manufactured, is substantially impervious to air, but which is provided with a large number of burrless perforations in average diameter from about 'l/zoo'to about l/iouo-ofan'lnch and in distribution from about 10 to lilo per square inch whereby the air perviousness of said envelope is substantially increased.

6. An air pervious paper' container comprising an envelope provided with a large number of burrless perforations in average diameter from about 1/zclo to about l/umo of an inch and in distribution from about 10 to 100' per square inch whereby the air pervlousness of said envelope is substantially increased.

7. A paper bag closed except for a relatively small valved filling opening to snugly receive a filling spout, adapted to contain. pulverulent material and formed with a large number of electric arc pierced, burrless perforations minute enough to prevent any substantial amount of pulverulent material from sifting out of the bag therethrough in number and spaced closely the bag to substantially increase the air perviousness of the bag, whereby, through escape of air through said perforations bag is facilitated, and in handling the bag, internal bursting stresses are reduced.

8. A multiple ply paper bag closed except for a relatively small valved illing opening to snugly .receive a lling spout, adapted to contain pulverulent material, the several plies of which are formed with a large. number of electric arc pierced, burrless perforations minute enough to prevent any substantial amount of pulverulent material from sifting out of the bag therethrough but sufllcient in number and spaced closely venough togetherover a large enough area of the bag to substantially increase the air perviousnes's of the bag, whereby, through escape of air through saldi perforations the filling of the bag is facilitated, and in handling the bag, internal bursting stresses are reduced.

9. A paper bag closed except `for a relatively small valved filling opening to snugly receive a lling spout, adapted to contain pulverulent ma teriai and formed with a large number of electric arc pierced, burrless perforations minute enough to prevent any substantial amount of pulverulent material from sifting out of the bag or water or `any substantial amount of atmospheric moisture from entering the same therethrough but suiclent in number and spaced closely manning of the' A enough together and over a large enough area of -small valved iilling opening to snugly receive a filling spout, adapted to contain pulverulent material. and formed with a large number or electric arc pierced perforations having clean out, burrless edges whichare given increased resistance .to rupturing stresses through the action of the y electric arcs so that the perforations do not substantially diminish the strength of the paper, are

fmin'ute enough to` prevent any substantialv amount of pulverulent material from sifting out of the bag therethrough but which are sumcient in number and spaced. closely enough together .and over a large enougharea of the bag to substantially Iincrease the airperviousness of the bag, whereby, through escape of air through said perforations the filling of the'bag is facilitated, and in` handling the bag, yinternal bursting y stresses are reduced..

' 1l. A paper bag vclosed except for a relatively small valved rlllingvopening to snugly fit a illling spout, adapted to contain pulverulent material and formed over a major portion of its area with a large number-.g` of closely spaced electric arc 15. Method of treating the paper of a paper container to increase the air perviousness of the container, without substantial decrease in itl strength, which comprises: piercing the paper constituting the container with a large number of minute, widely distributed perforations made by the action of electric arcs whereby a constituentof the paper is acted upon to form strengthening ring-like bodies of dense material around said perforations.

16. Methodof treating the paper of a paper i container to increase the air perviousness of the pierced burrleSS.l perforations minute enough so `-thatI any substantial amount of pulverulent ma- ',ter'ial isprevented from sifting out of the bag therethroughfbut sunicient in number tosub- 'stantiallyincrease the air perviousness of the bag,`whereby, through` escape of air through said perforations, thevillling of the bagr is facilitated and, in handling the baELinternal bursting stresses are reduced.

12. A paper container formed with a multitude yIof'm'inute, widely distributed electric arc pierced perforations characterized byclean cut, 'burrless edges which are given increased resistance to rup.- turing stresses through the action of the electric arcs whereby the perforations of the paper, while materially increasing the air perviousness` of the "container, does not substantially vdiminish its strength.

container, without substantial decrease in its strength, which comprises: piercing the paper constituting the container with a large number of minute,'wide1y distributed perforations made by the action of electric arcs.

V1'?. A paper container which for the major portion of its area is formed with a multitude of minute, electric arc pierced perforations which add materially to the air perviousness of the container without substantially diminishing its strength.

18. A paper container which for substantially its entire area is formed with a multitude of minute, electric arc'pierced perforations which add materially' to the air perviousness 0I the container without substantially diminishing its strength.

19. An air pervious paper bag provided with a relatively small filling opening adapted to snugly ilt a filling spout and comprising: an envelope formed with a multitude of electric arc pierced 13. A paper bag closed except for a filling open- I ing adapted to snugly fit a nlling spout formed with a multitudev of minute, widely distributedl electric arc pierced perforations characterized by clean cut, burrless edges which are given increased resistanceI to rupturing stresses through the action ofthe electric arcs whereby the perforation of the paper, while materially increasing the airperviousness of theirbag and thereby facilitating the lling of the same, does not sub stantially diminish its strength.

14'. A paper eonta'i er formed with la multitude y of minute, widely distributed electric arc pierced perforations whichv add materially to the air perviousnes'sfof the container without substantially diminishing its strength.

perforations characterized by burrless, clean cut and strengthened edges, which perforations are in average diameter from about lo@ 'to' about i000 of an inch and in distribution from about 10 to 100 per square inch over a maior portion of the area of said envelope, whereby the air perviousness of the envelope is substantially increased without substantial diminution of the strength thereof.

20. An airpervious paper container comprising: an'envelopeformedwith a multitude 'of electric arc pierced perforations characterized by burrless, clean cut and strengthened edges, which perforations are in average diameter from about 00 to about ooo of an inch and in distribution from about 10 to 100 per square inch over a major portion of the `area of said envelope, whereby the air perviousness of the envelope is substantially increased without substantial diminution of the y strength thereof.

21. Method. of making paper containers which comprises: providing a web of strong relatively dense paper; piercing said web with a large number of minute widely distributedperforations through the action of electric arcs; and forming containers from said treated web in such manner `that the containers have greater air perviousness than the original web but with substantially the same strength.

JOHN W. MEAKER.

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