Photographic Bag

Abstract

This disclosure relates to a bag constructed particularly for the packaging of products which are subject to further chemical reaction, i.e., chemical changes produced in substances by light being absorbed directly, by reflection, or by transmission, whether infrared or ultraviolet, as well as from the visible rays of the spectrum, the bag being formed as a seamless homogeneous one-piece tube flattened upon itself to define a pair of oppositely disposed flattened edge portions, the tubing constructed from synthetic generally opaque plastic material, the flattened material being folded upon itself at least once to bring the flattened edge portions into contiguous relationship and form at least a two-ply tubular member, means securing the edge portions to each other to define a tubular member having axially opposite end portions, and means closing at least one of said end portions.

Description

The present invention is directed to a bag or any other type container in which is adapted to be packaged products which are normally adversely affected by a photochemical reaction, more specifically among which are such products as photographic film or plates which after exposure must be maintained in a light-free atmosphere until developed. Though the present invention is directed particularly to preventing direct light from being absorbed by exposed photographic film or plates, the bag of the present invention is useful for packaging any product which is affected, either good or bad, by light rays, be they visible, infrared, ultraviolet, etc., and whether the light is reflected, transmitted or direct. As an example, exposed photographic film or plates are packaged in so-called "lightproof" bags or similar containers because once having been exposed further absorption of light by the silver salts of the film emulsion results in the transfer of the silver salts into metallic silver, which when developed, produce dark or overexposed area thus ruining the desired exposure. This is true of both black-and-white and color film with the exception that in the latter there are a plurality of silver salt-emulsion layers with each layer containing a "coupler" to produce a desired colored dye. However, in each case, extraneous undesirable light will virtually ruin any exposure and though perhaps of major concern to amateur and professional photographers in general, more importance should be attached to such arts as photocomposition, photoengraving, photogrammetry, photographic copying, photomicrography, etc., wherein the destruction of a particular exposure due to light leakage after exposure and prior to development due to packaging defects would present a vastly more important consideration than the loss of merely a good "snap shot."

At present, the major problem of packaging exposed photographic films or plates is simply that of precluding the introduction of light rays, be they visible, ultraviolet, or infrared into the interior of commercially available packages. Most important is what is known in the industry as "pinholes" which are simply voids which transmit light into the interior of packages designed to house exposed photographic articles. One solution, though relatively expensive, is that of extruding a coating of carbon black pigmented synthetic plastic material, such as polyethylene, on dark (preferably black) paper, and forming the paper into a tube which eventually forms the liner of a duplex bag.

Another attempted solution is that of forming a laminate of at least three plies which eventually is formed into a bag in which an outer ply is formed of paperstock material, an inner ply of opaque pigmented synthetic plastic material, and an inner liner of metallic foil, or vice versa. From a commercial standpoint both of these so-called "solutions" are costly since the first involves achieving as perfect as possible a dispersion between the opaque pigmentation and the plastic material, the uniform application of the latter upon the dark paper, and thereafter the unification of this two-part construction to an outer overwrap. As to the latter, this adds the additional difficulty in cost involved in laminating a foil liner and/or overwrap thereto.

Another common duplex bag for this purpose employs paperstock material, such as kraft paper and a laminated opaque pigmented polyethylene liner. In order to gain maximum opacity the polyethylene liner is generally pigmented with carbon black or any similar type opaque substance. However, even when the carbon black pigmentation rate is relatively high and the gage of the polyethylene film is two or three mils, a completely opaque bag does not always result because of occasional "pinholes" in the film due to gel particles, incomplete pigment dispersion, and the like. As was heretofore noted, such areas of light transmission can and will result in the damage or total loss of exposed film, be it photographic film, photographic plates, or even the fogging of X-ray film.

In order to practically, though not necessarily, eliminate the possibility of light penetrating into the interior of this structure, it might be theoretically feasible to employ two pigmented polyethylene liners, each of which would be somewhat thinner than the single liner heretofore noted. This might be effective since the possibility of the occasional pinholes in the two films actually coinciding or aligning would be virtually nil. However, the use of two polyethylene or any other type liners is not practical for a variety of reasons. First, the simultaneous machining of two separate extremely lightweight and extensible or stretchable liners on commercial bag machines is virtually if not totally impossible and if possible would undoubtedly result in extremely low operating speeds and high waste. Furthermore, there are no known commercially available adhesives of the emulsion-type required on bag machines which will provide adequately strong bonds between the two polyethylene plies either in the bag body or the bag bottom. Finally, even should such adequate emulsion-type adhesives be developed for this purpose the use between two relatively moisture impermeable plies of film, such as polyethylene, would necessarily result in the need to "age" the bags several weeks before use so as to provide an opportunity for air to dry out and setup the adhesive.

In keeping with the foregoing invention, each and every of the foregoing noted disadvantages of known "lightproof" packages have been eliminated by the construction of a bag in keeping with the present invention which is formed as a seamless homogeneous one-piece preferably extruded tube of synthetic plastic material containing a random dispersion of impregnated opaque material, the tube being flattened upon itself, and thereafter the flattened tube being folded upon itself at least once to bring flattened edge portions into contiguous relationship. After having been longitudinally seamed along the flattened edge portions and transversely closed any light-transmitting voids produced by the dispersion in either of the two plies will invariably not fall into alignment due to the flattening of the tube upon itself.

By this structure alone, it should be first noted that the bag can be constructed from but a single tubular member, and if desired the same may be provided with an outer overwrap. However, in the latter case, it is unnecessary to extrude the plastic-opaque dispersion upon a dark paper background to form a liner and if desired unite the same with an outerwrap or unite three plies as in the case of commercially available paper-pigmented plastic-foil packages. Moreover, the difficulty of extruding two thin extensible webs, adhesively uniting the same, longitudinally seaming the same, and then using the same individually or with an overwrap is also avoided. Finally, in the latter case the problem of adhering impermeable plastic web material to each other to form commercial bags of the type heretofore described is avoided since it is absolutely unnecessary and in fact undesirable to adhere opposing surfaces of the flattened tube to each other. Furthermore, whether used in the absence of an overwrap or with an overwrap each disadvantage of commercially known "lightproof" bags is eliminated by the bag and/or liner of the present invention.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawing.

IN THE DRAWING:

FIG. 1 is a perspective view of a novel bag constructed in accordance with the invention with portions thereof broken away for clarity, and illustrates a seamless homogeneous one-piece tube flattened upon itself with flattened longitudinal edge portions being heat-sealed to each other to define a lightproof bag which is usable per se or in conjunction with an outerwrapper to form a duplex bag.

FIG. 2 is a diagrammatic sectional view taken through the flattened bag or liner of FIG. 1 prior to the same being folded upon itself in the manner indicated by the unnumbered headed arrows.

FIG. 3 is a view similar to FIG. 2 illustrating flattened longitudinal edge portions of the liner and/or bag in contiguous relationship, and indicating the manner in which opposing plies are sealed to each other.

FIG. 4 is an enlarged sectional view taken generally along line 4--4 of FIG. 1, and illustrates the flattened, folded upon itself and longitudinally seamed tubular member forming a liner in association with the outerwrapper.

FIG. 5 is an enlarged fragmentary sectional view taken generally along the line 5--5 of FIG. 1 prior to the completion of the bag, and illustrates the manner in which the bottom end portion is twice folded upon itself to complete the fabrication of the duplex bag.

Before describing a preferred embodiment of the present invention, it is pointed out hereinat that the present invention is directed primarily to a bag formed as a seamless homogeneous one-piece tube constructed from synthetic generally opaque plastic material flattened upon itself to define a pair of oppositely disposed flattened edge portions which are folded into contiguous relationship and sealed to each other to form a tubular member which when closed forms a lightproof structure which eliminates the disadvantages heretofore noted with respect to conventional packages.

Though the "bag" is preferably of a duplex structure i.e., is formed with the opaque flattened and folded tube constituting a liner associated with an outer overwrap, it is to be understood that the "liner" per se may be a "bag" per se and need not be used in association with the outer overwrap. Moreover, though the tube is disclosed as being flattened upon itself and folded but once to bring longitudinal folded edge portions into lap relationship with each other, it is to be understood that more than but a single folding may be employed to form more than but a two-ply structure.

Referring particularly to FIG. 1 of the drawing, a novel bag constructed in accordance with this invention is generally designated by the reference numeral 10 and as a preferred embodiment of the invention the bag 10 is a "duplex" bag which includes an inner bag or liner 11 and an outer bag or overwrap 12.

The overwrap 12 is of a completely conventional construction and is constructed from paperstock material, such as kraft paper, or any other flexible foldable material which from a web is formed into a tube having a front wall or panel 13, a rear wall or panel 14, opposite gussetted sidewalls or panels 15, 16, and a bottom portion 17 folded upon itself twice with adhesive A (FIG. 5) uniting the lowermost portions (unnumbered) of the walls 13, 14 to each other in a conventional manner. Longitudinal edges 18, 20 are, of course, adhesively secured to each other by adhesive, which is indicated by the stippling in FIG. 1, or by any other conventional means.

The liner or bag 11 of the duplex bag 10 is designed particularly for the packaging of products which are subject to photochemical reaction, as was heretofore noted, and comprises a seamless homogeneous one-piece tube flattened upon itself (FIG. 2) to define a pair of oppositely disposed flattened edge portions 21, 22. The tube or bag 11 is constructed from synthetic generally opaque plastic material, such as polymeric or copolymeric plastic material, most preferably of which is polyethylene. The flattened tube, which for purposes of discussion will be more specifically designated by the reference numeral 23 (FIG. 2) includes in addition to the folded longitudinal edge portions 21, 22, two walls or plies 24, 25. The tube 23 is of a predetermined length and thus includes unnumbered upper and lower end portions, the latter of which is closed upon the folding of the duplex bag 10 and the securement of the walls 13, 14 to each other by the adhesive A in the manner heretofore noted.

In addition to being constructed from plastic material, the tube 23 is extruded after the material thereof has been first intermixed with a generally opaque material nontransmissive to light, such as carbon black. The opaque material is admixed with the plastic material (polyethylene or the like) and is formed into an impregnated dispersion which under ultimate conditions would prevent the transmission of light. However, even if the opaque dispersion (carbon black or an equivalent material) is relatively high and the thickness of the film is similarly high (2-3 mils) a completely opaque bag will not always result because of occasional "pinholes" (light-transmitting voids) in the film due to gel particles, incomplete pigment dispersion, and the like. To prevent such light transmission and avoid the disadvantages in known packages heretofore noted, the tube 23 is first flattened upon itself (FIG. 2) and is then folded upon itself at least once to form a folded two-ply tubular member 30 (FIG. 3). The flattened edge portions 21, 22 are in overlapped relation but, as claimed, the term "contiguous" is intended to mean not only the overlapped relation illustrated in FIGS. 1, 3 and 4, but also end-to-end butt relationship or a space relationship with any type seam therebetween such as a strip of tape extending along the longitudinal length of the edge portions 21, 22 so long as the tape is of a lightproof construction. Moreover, a "fin" type seal is also intended by the term "contiguous" as is any construction in which the edge portions 21, 22 are joined to each other in any manner, either directly or by an intervening structure.

Upon folding the flattened tube 23 upon itself to form the tubular member 30 the flattened tube 23 is likewise provided with flattened inner folded edge portions 31, 32 of a two-ply construction, as opposed to the four-ply construction of the edge portions 21, 22. Furthermore, instead of being of a single ply as is the flattened tube 23 defined by the walls 24, 25, the tubular member 30 is of a two-ply construction defined by the now folded upon themselves walls 24, 25 which for purposes of description are indicated more exactingly by the reference numerals 34, 35 indicating the respective outer and inner plies of the tubular member 30. As is best illustrated in FIG. 4, the contiguous edge portions 21, 22 of the tubular member 30 are secured to each other by longitudinal seam 36 which is preferably a heat-seal between the portion (unnumbered) of the plies 34, 35 in opposed relationship to each other at the edge portions 21, 22. Though the heat seal 36 is a preferable way of adhering the edge portions 21, 22 to each other, it is to be understood that other conventional means may be employed for this purpose.

The tubular member 30 includes, of course, upper and lower end portions (unnumbered) which are coincident with those of the outerwrapper 12, and the lower end portions is, of course, closed upon the overfolding end securement of the wall 13, 14 to each other by the adhesive A. However, it is to be particularly noted that apart from the adhesive A and the securing means 36 no further securement is provided between the outer ply 34 and the inner surface (unnumbered) of the outerwrapper 12 or between the outer ply 34 of the tubular member 30 and the inner ply 35 thereof. Adhesive may, of course, be provided between the outer surface of the outer ply 34 of the tubular member 30 and the inner surface of the outerwrapper 12. However, most importantly, is the fact that no means whatever is provided for securing the inner surface of the outer ply 34 of the tubular member 30 to the outer surface of the inner ply 35, as is clearly indicated in FIG. 3. This is important because, as was heretofore noted, emulsion-type adhesives are presently unavailable for adequately securing moisture-impermeable material, such as a material from which the tubular member 30 is constructed, to itself. Moreover, as was heretofore noted even if such type adhesives were developed, and they were applied between the plies 34, 35 it would be necessary to "age" or store the eventually formed duplex bags and to permit air to set or cure such adhesives prior to shipment and/or use. Thus, by forming the flattened tube 11 as a seamless homogeneous blow-mold member, it is unnecessary to adhere the plies of the eventual folded tubular member 30 to each other thus avoiding the added cost of storage space which would be required for the purpose of aging or curing the adhesive and, moreover, production is increased since the only two seals which form the duplex bag 10 are the seals 36, which is a heat-seal requiring little or negligible aging and the seal formed by the adhesive A which because it is between a paper-paper interface is aged or cured sufficiently after leaving the bag-forming machine to be stacked, packaged and shipped in the absence of interim storage. This is because the paperstock material of the overwrap 12 is porous and air and/or heat rapidly sets the adhesive, and thus there is no delay time prior to shipping as might be necessitated if an adhesive were applied between the impermeable plies 34, 35 of the tubular member 30.

It is pointed out that the construction of the duplex bag 10 is formed in a continuous manner by first extruding a tube of thermoplastic material, flattening the extruded tube to form the tube 11, folding the tube 11 to form the tubular member 30, seaming the edge portions 21, 22 of the latter as the same is being continuously advanced, and at the same time overwrapping the overwrap 12 thereupon and forming the longitudinal seam after which transverse severing of individual lengths and the closure of one end to form the bag 10 is completed in a well known fashion. Furthermore, though the duplex bag 10 is disclosed as being provided with gussetted sides 15, 16, these may be eliminated and/or altered as may be necessary, as may be the particular construction of the bottom closure of the bag by the adhesion of the wall 13, 14.

It is further emphasized that though the folding of the flattened tube 11 upon itself has been indicated as being a direct fold of the edge portions 21, 22 upon themselves, as shown in FIG. 3, additional folding prior to securement may be provided. For example, instead of the folding indicated by the unnumbered headed arrows in FIG. 2, the edge portions 21, 22 could be brought into overlying relationship but directed in the same direction to form another longitudinal fold remote therefrom and the latter longitudinal fold could then be brought into overlapped relationship to the edges 21, 22 after which longitudinal seaming could be achieved. This would achieve added plies equivalent, of course, to folding the tubular member 30 to bring the edges 31, 32 into continguous relationship after which the same could be longitudinally seamed. This produces additional assurance against light transmission but does so at added cost, but reference thereto is believed necessary to highlight the intent of the following claims.

Irrespective of the particular configuration of the bag or liner 10, it is to be understood that the essence of the present invention is that of first forming the tube 11 as a homogeneous nonlight transmissive member which, though it may have "pinholes," by simply flattening the same to the configuration shown in FIG. 2 alignment of any pinholes in the plies 24, 25 is virtually, if not positively, precluded. Thus, imagining photographic film or plates being housed interiorly of the inner ply 35 of the tubular member 30 with the edge portions 21, 22 seamed, exterior light must not only pass through pinholes of the exterior ply 34 but must also pass through aligned pinholes of the interior ply 35 before the contents of the bag 10 could be damaged. Due to the virtual impossibility of such alignment of pinholes the bag 10 is "lightproof."

Claims

I claim:

1. A bag constructed particularly for the packaging of products which are subject to photochemical reaction comprising a seamless homogeneous one-piece tube flattened upon itself to define a pair of oppositely disposed flattened edge portions, said tube being constructed from synthetic generally opaque plastic material, said flattened tube being folded upon itself at least once to bring said flattened edge portions into contiguous relationship and form at least a two-ply tubular member, means securing said edge portion to each other to define a tubular member having axially opposite end portions, and means closing at least one of said end portions.

2. The bag as defined in claim 1 wherein the opaque nature of said plastic material is defined by opaque material impregnating said plastic material.

3. The bag as defined in claim 1 wherein the opaque nature of said plastic material is defined by opaque material impregnating said plastic material, and said opaque material is randomly disposed in said plastic material whereby any light-transmitting work produced by said dispersion in either of said at least two plies are prevented from transmitting light to the bag interior by the other of said two plies due to the flattening of said tube upon itself.

4. The bag as defined in claim 1 wherein said tube is formed by extruding an admixture of said plastic material containing a random dispersion of opaque material.

5. The bag as defined in claim 1 wherein said two plies are free of each other over substantially the entire interior extent of said tubular member excluding said securing and closing means.

6. The bag as defined in claim 1 including an outer overwrap member substantially housing said tubular member.

7. The bag as defined in claim 1 wherein said securing means is a heat seal.

8. The bag as defined in claim 1 including an outer overwrap member substantially housing said tubular member, and means securing an outermost ply of said tubular member to said overwrap member between the axially opposite end portions of the latter.

9. The bag as defined in claim 1 including an outer overwrap member substantially housing said tubular member, means securing an outermost ply of said tubular member to said overwrap member between the axially opposite end portions of the latter, said plastic material being substantially moisture impermeable, said overwrap member being moisture permeable, and said last-mentioned means being an air-setting adhesive.

10. The bag as defined in claim 1 wherein said flattened tube is devoid of adhesive means between innermost opposing surfaces thereof.