US 3099464 A
Description (OCR text may contain errors)
July 30, 1963 G. w. SMITH 3,099,464
PLASTIC PROTECTORS FOR SHEET MATERIAL, BQOK AND MAGAZINE COVERS, AND THE LIKE Filed Aug. 1. 1960 2 Sheets-Sheet l INVENTOR. GENE W. SMITH TORNEY.
July 30, 1963 G. w. SMITH 3,099,464
PLASTIC PROTECTORS FOR SHEET MATERIAL, BOOK AND MAGAZINE COVERS, AND THE LIKE Filed Aug. 1. 1960 2 Sheets-Sheet 2 INVENTOR. 'FEENE W. SMITH ATTORNEY.
United States Patent LIKE Gene W. Smith, 5008 La Canada Blvd, La Canada, Calif. Filed Aug. 1, 1960, Ser. No. 46,666 15 Claims. (Cl. 281-20) This invention relates to reusable protectors for sheet material and more particularly to a transparent plastic protector of simple, inexpensive construction specially adapted to be readily assembled to file cards, drawings, leaflets, magazine covers, book covers and the like to protect the same against soiling and damage through handling.
Public reading rooms, salesmen, mechanics, artisans and many others have need for displaying printed material, working drawings, sales literature and other material without interference with the legibility of the printing and while protecting it from soiling and damage by handling. A similar need exists in reading rooms, the classroom, and elsewhere to protect book and magazine covers. Various expedi-ents have been proposed heretofore to meet these needs but none have the versatility, convenience and economy, or afford the degree of protection desired in a satisfactory product of this type. In most instances the protectors heretofore provided are specifically designed for a particular application and are not readily adaptable to other operating environments without substantial changes in design. Furthermore, prior protectors are characterized by their prohibitive cost, unnecessary bulk and the need for special skill or equipment for assembly to the material to be protected.
In view of the foregoing and numerous other disadvantages and shortcomings of the protective covers heretofore provided there is provided by the present invention an unusually simple, easily-employed and highly versatile protector readily adapted to be assembled to printed material in a wide variety of forms including both single sheets, folders, file folders, booklets, magazines, as Well as to books having stiff covers of differing thicknesses, as well as to looseleaf binders having hardboard covers held together by posts, metal staples and other expedients.
According to one mode of practicing the invention there is provided a stiff mounting stripgummed along one lateral edge portion only and adapted to be secured to the cover of a magazine, a book or to the back of a folded sheet, it merely being necessary in all cases to secure the free ungummed edge of the mounting strip parallel and contiguous to the hinge of the material to be protected. Once this strip is secured in place, a folded plastic doublet protector is assembled to this mounting strip by inserting the ungumm ed edge of the mounting strip in the groove of the ovenfolded lateral edge portion of the doublet. Thereafter the remainder of the plastic protector is fitted about the outer and inner surfaces of the cover to be safeguarded, it being understood that the size of the prefolded doublet protector is selected to correspond with the size of the cover or sheet to be protected. Preferably both covers or halves of the sheet to be protected are similarly enclosed using separate mounting strips and separate plastic doublets for each cover or each half of the material.
Another feature of the construction is the (fact that the doublet protector is provided with a slot in its overfolded edge of a size to accommodate an indexing tab mounted astride the edge of the sheet material being enclosed. If desired, the index tab may be loosely mounted astride the sheet as the sheet is being inserted within the protector with the result that, once assembled, the protector locks the index accessory in assembled position. Accordingly, if desired, the same accessory may be re- 3 ,099,464 Patented July 30, 1963 "ice 2 moved and reused any number of times with other sheet material.
Another feature of the doublet protector is the fact that the protector proper is made from a single piece of transparent flexible plastic material. Once assembled about a drawing or the cover of a magazine, all surface areas of both the interior and exterior sides of the cover or drawing being covered are fully exposed. This is particularly true if the mounting strip is formed of transparent plastic material, as is preferable, and if transparent pressure-sensitive adhesive is employed in holding it secured to the drawing or cover being protected.
According to another variant of the invention mounting strips may be dispensed with as Where the sheet material being protected comprises a file folder, drawing or the like folded along one center line and appropriately slit in the manner and for the purposes to be disclosed herein below.
Accordingly, a primary object of the present invention is the provision of a simplified inexpensive protective folder for sheet material adapted to be readily assembled to material to be protected and thereafter transferred and reused on other similar material.
Another object of the invention is the provision of a transparent plastic protector for drawings, leaflets, booklets, magazines and books with stiff covers and adapted to be held assembled thereto by the aid of a narrow mounting strip securable to the material adjacent one lateral edge thereof.
Another object of the invention is the provision of a pre-foided plastic doublet protector adapted to be held assembled to sheet material by the engagement of an overturned edge of the protector and likewise adapted to look an index tab temporarily assembled to an edge of the material being protected so long as the protector is in place thereover, the protector and indexing tab being reusable repeatedly on other sheet material at the users option.
Another object of the invention is the provision of a new and improved method of protecting the covers of notebooks, magazines and the like and effective to reinforce and supplement the strength of such covers while leaving both obverse and reverse surfaces fully exposed to view.
Another object of the invention is the provision of a thin flexible plastic protector adapted to be quickly and easily assembled about sheet material and adapted to be retained in intimate contact with such material by electrostatic attraction provided as by momentary brisk rubbing of the protector.
Another object of the invention is the provision of a novel method of protecting photographs, sales literature, and the like Without defacement of the photo or the face of the printed matter and while leaving the complete contents of the protector exposed to view.
These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawings to which they relate.
Referring now to the drawings in which preferred embodiments of the invention are illustrated:
FIGURE 1 is an exploded view of one preferred embodiment of the invention and indicating the manner in which the doublet protector is assembled to the front and rear covers of a booklet;
FIGURE 1-A is an end view on an enlarged scale of one of the mounting strips prior to being mounted on sheet material;
FIGURE 2 is an end view on an enlarged scale according to FIGURE 1 showing the protector (for the front cover fully assembled and the rear cover protector in the final stage of the assembly;
FIGURE 3 is an exploded view of a second preferred embodiment of the invention wherein the contents of the protector comprises a single folded sheet, the view representing the doublet protectors for the two halves of the file card in the process of assembly;
FIGURE 4 is a fragmentary view of the FIGURE 3 embodiment and the manner in which it is assembled to retainer tabs integral with the sheet being covered;
\FIGURE 5 is a fragmentary plan view of the invention according to FIGURES 3 and 4 showing the protector fully assembled to one of the retainer tabs;
FIGURE 6 is a fragmentary view partly in section on an enlarged scale showing details of the indexing tab and the manner in which it is held detachably assembled to the file card so long as the protector is in place;
FIGURE 7 is a cross-sectional view on an enlarged scale taken along line 77 on FIGURE 5;
'FIGURE 8- is a perspective view showing the further modification of the protector in the process of being assembled to a folded sheet;
FIGURE 9 is a fragmentary plan view on an enlarged scale showing one protector assembled to a folded sheet with the interior flap of the protector locked closed;
FIGURE 10 is a fragmentary sectional view taken along line 10'10 on FIGURE 9; and
FIG. 11 is a small scale perspective view of a hinged connector and usable in lieu of the mounting strips employed in FIGURES 1 and 2.
Referring first to FIGURES l and 2, a first preferred embodiment of the invention is shown in the process of being assembled to the covers of a booklet or magazine 14 having the usual front and rear covers 1 and 12 connected to one another along the hinge 13. The cover is held assembled to the interior pages by a suitable binding, as for example, by staples 15. It will be understood that the booklet or magazine is merely representative of either a single folded sheet or of multiple sheet bound material including material having both soft and hard covers, notebooks, looseleaf binders and the like. It will also be recognized that it is immaterial whether the sheet material being protected is bound to other material since the sheets to be protected by the present invention may include sheet material of any kind including single sheet drawings, photos, maps and miscellaneous printed material generally, as will be'better appreciated as the desecription of the invention proceeds and its essential principles are pointed out.
The protector component proper of the first preferred embodiment includes one or more mounting strips 18 and one or more protector doublets 20. Both components are preferably made from the same material, as for example, thin, hard, smooth-surfaced, abrasion resistant, transparent plastic material of which numerous commercially available compositions are suitable. Preferably, a thermosetting material is employed since this is easily formed and creased while heated to retain a permanent set in a desired configuration. Sheet plastic having a thickness of a few mils is preferred since it is light in weight, inconspicuous in bulk, economical, and provides highly satisfactory protection for both thin paper and hardboard covers and yet has adequate strength to supplement and provide desirable protection for magazine covers and the like light paper stock.
Mounting strips 18 are here shown as extending for substantially the full length of binge '13. However, it will be apparent that the mounting strips may be cut in shorter lengths and spaced at intervals along the covers adjacent the hinge following the same general procedure to be described presently in connection with the mounting of full length strips. Desirably, mounting strips 18 are formed of stiffer material than doublets 20 and may comprise plastic, fiberboard or reasonably stiff paper stock. The mounting strips are provided with a narrow band of adhesive 22 confined toone lateral edge portion of the strip leaving the other edge port-ion 23 free of adhesive 4 for a width somewhat in excess of the depth of the groove formed therefor in protector 2t). Adhesive 22 may be of the water soluble type or the pressure-sensitive type. As is clearly apparent from FIGURES 1 and 2, mounting strips 18 are secured to the front and rear covers 11 and 12 of the leaflet with the rear free edge 23 of the strip parallel and closely spaced to the axis of hinge 13.
Referring to FIGURE 1-A, it is pointed out that the strip 22 of adhesive applied along one edge of mounting strip "18 may be either water soluble or pressure-sensitive. in the latter case, it is desirable to cover the outer surface with a thin protective strip 22a of inexpensive material readily separable from the pressure-sensitive layer 22. To facilitate removal of protective or guard strip 22a, the latter is made wider than the band of pressure-sensitive material to provide a pull tab 22b along one edge easily lifted by the fingernail and grasped between the users thumb and finger.
Doublets 20, 2th for a given magazine or booklet are identical and have a folded size corresponding generally to that of the cover or material to be enclosed and protected. Actually the full size of the unitary piece of material used in forming the protectors is greater than the combined interior and exterior surface areas of the cover by a small amount corresponding to the area of the overturned lateral edge strip 25 employed to form seating groove 26-. Each doublet protector is thus seen to comprise a front sheet 27 connected to the rear or inner sheet 28 by a reversely folded hinge 29 and, in addition, the overturned lateral edge strip 25 integral with the free edge of front sheet 27. As manufactured, the transparent sheet material is preformed with the two hinges along the opposite lateral edges of front sheet 27 with back sheet 28 lying flush against the rear side of sheet 27. If desired, the doublets may be punched along the lateral edges with holes 32 to permit binding of the ma terial in a looseleaf or post-type binder.
The manner of assembling the doublet protector to a magazine or other material to be protected will be readily apparent from the foregoing description of the construction and the relationship of its components to one another. Assuming that it is desired to mount the protector on both the front and rear covers of the booklet or magazine 14, the operator first secures mounting strip 18 to the covers in the manner described in detail above. Once these strips are firmly in place and the adhesive has taken a set, the operator unfolds one of the doublets 20' to the position shown in FIGURE 1 and inserts the free rear lateral edge portion 23 of one of the mounting strips within seating groove 26 of the protector formed along the free edge of front sheet 27. The Width of groove 26 is negligible and less than the thickness of the mounting strip with the result that the opposite sides of the seating groove form a snug frictional fit with the contacting surfaces of the mounting strip. When the free edge of the mounting strip is fully seated in groove 26, hinge 29 will lie directly opposite the forward edge of cover 11. The operator merely lifts the cover and folds interior sheet 28 of the doublet smoothly against the interior surface of the cover so that the free edge 30 of sheet 28 will lie closely adjacent cover hinge 13. Since in the relaxed normal positions sheets 27 and 28 of the doublet tend to lie closely adjacent one another, they will naturally lie flush against the opposite surfaces of the cover whenever this cover is. lifted away from the interior contents of the booklet. The assembly of the second mounting strip and the rear cover protector is accomplished in the same manner described above for front cover 11.
T o be noted is the fact that when the doublet protectors are in their assembled positions, the entire surface areas of the cover are fully protected both interiorly and ex teriorly. Furthermore, the clear and transparent nature of the protector leaves all surface areas of the cover fully exposed to view. In fact, the protector enhances the appearance of the material due to its smooth, glossy appearswee e ance. Since it lies fully flush with the cover surfaces and remains there despite flexing of the cover page, it gives the impression of being adherent to (the cover surfaces. Nevertheless, the protector is quickly and readily removable and transferable to another booklet after there is no longer need for it on the prior booklet. Thus, the protector is reusable repeatedly, it merely being necessary to use new mounting strips 18 for each assembly op eration.
A second embodiment of the invention shown in FIG- URES 4 to 7 employs essentially the same doublet protector construction 20 dmcribed above in connection with FIGURES 1 and 2. The protector differs only in the provision of an elongated cutout or slot 35 directly along hinge 29 to receive and fit over tab 36 of an indexing accessory 37. This accessory comprises a tab 36 firmly affixed centrally to the crest of a U shaped mountof greater length than tab 36. The interior facing surfaces of strips 38 may but need not be coated with an adhesive to secure the strips astride the edge of the sheet materim being indexed. When the indexing accessories 37 are employed vvith the present invention, the adhesive on the interior surfaces of strip 38 need not be used owing illO cooperative action of the doublets in holding them in place on the page edge. Accordingly, it is merely necessary to place the U-shaped strips 38 astride the edge of the page in the proper position for tab 36 to project through slot 35. Once the assembly operation is completed, it will be recognized that the indexing accessory is positively locked in assembled position.
Whenever it is desired to transfer the indexing accessory along with protector 20 to other subject matter or to substitute one indexing accessory for another, it is merely necessary to open the protector to release the indexing accessory. Although such an accessory is not shown in the embodiment of FIGURES :1 and 2, it will be understood that one can be used by the simple expedient of forming a receiving slot 35 in the appropriate position along hinge 29 of protector 20. If desired, the edge of the sheet may be provided with inconspicuous marks 39 spaced uniformly therealong and corresponding with different standard locations of slots 35 in the doublets.
The sheet being protected in FIGURES 3 to 7 comprises a unitary rectangular sheet of material 40' creased along its transverse medial line to provide a hinge 41 connecting the two halves of the sheet. In addition, sheet 40 is provided with two pairs of tabs 42, 43 formed directly from sheet 40 and having the shape and general dimensions clearly indicated in FIGURES 3, 4 and 8. The free edges of each of tabs 42, 4-3 is substantially coincident with hinge 41 and the opposite ends of the tabs are sufficiently long as to permit tabs 42, 43 to fit easily within groove 26' provided by the turned-back lateral edge 25 of doublet 20'. As shown in FIGURES 3, 4 and '5, flap 25 is free of slits throughout its length, as is true of the FIGURES 1 and 2 construction.
The protectors 20' are assembled to the opposite halves of the file folder or other sheet material 40 to be covered in the manner best illustrated in FIGURES 3 land 4. For example, folder 40 is folded substantially closed while the two tabs 42 on one of the folder halves is flexed outwardly to seat within groove 26' of protector 20 after the latter has been opened in the customary manner. FIGURE 3 illustrates the position of the parts after one pair of the tabs 43 has been seated within the groove 26, attention being called to the fact that only the portion of strip 25' corresponding to the length of tabs 43 is then positioned or exposed on the inner side of folder 4f), the remaining length of strip 25 being confined to the opposite or outer side of folder 40. This is further indicated in FIGURE which is a view taken from the interior side of the assembly and showing in full lines the exposed interior portion of strip 25, the remainder of the strip or turned-back portion appearing in dotted ing strip 38 line toindicateit is on the reverse or outer side of folder 40. The next step is to place index accessory 37 astride the free edge of the folder in position for its tab 36 to project through slot 35. After this assembly operation has been completed, it remains to fold the interior sheet 28' of the doublet'inward-ly to lie flush against the surface of folder 40 with its free edge 30" lying closely against folder hinge 41. Thereafter the other half of folder 40 maybe similarly covered with a second doublet protector 20' if the user so wishes. If not, this half of the folder is left unprotected.
Although sheet 40 has been referred to, in the description of FIGURES 3 to 7, as a file folder usually formed of manila paper or the like relatively stiff paper, it will be understood that sheet 40 may comprise a bro? chure, machine shop drawing, a road map, or printed material of any character, and that the folding and slitting of the central portion of the sheet to for-m tabs 42, 43 does not interfere with the readability of'these portions owing to the fact that in the open position of the folder these areas are fully exposed and readable through the transparent portions of strips 25'.
In the third embodiment illustrated in FIGURES 8 to 10, the folder or material to be protected, designated generally 40, is identical with the folder described in FIGURES 3 to 7. The transparent plastic doublet 20 is also identical with that described in connection with FIGURES 3 to 7 with the exception that the overturned strip 25" is slit transversely at spaced intervals to form locking tabs 45 directly opposite and corresponding generally in size and length to tabs 42 and 43 of the sheet material. The doublets 20" are assembled to sheets 40 in exactly the same manner described above except that the slitting of strip 25' permits tabs 45 to be used to embrace the interior free edge 30" of inner sheet 28 in the manner clearly illustrated in FIGURES 9 and 10. Accordingly, the protector is not only locked to sheet 40 but its inner free edge 30 is held firmly locked in assembled position. a
In summary, it is also pointed out that in a further obvious variant of the invention the mounting strips 18, 18 of the FIGURE 1 embodiment could be secured to the opposite edges of a hinged strip unit having the general construction shown in FIGURE 1 1 and being suitable for use to embrace the thin magazine-s, pamphlets, folded drawing sheets and the like. Such a unit functions exactly in the manner described with reference to FIGURES 1 and 2 except that it is unnecessary for the user to secure the mounting strips directly to the cover of the material being protected.
The hinge accessory is of generally W-shape in crosssection, the outer pair of legs 18' providing mounting strips seatable in grooves 26 of the doublet protectors 20. The two center legs of the strip form a V-shaped hinge strip 48 and are formed of suitable material such as stiffened fabric, plastic or the like. The hinge unit may be folded from a single piece of material but in this event it is desirable that the junctions of legs 18" with the hinge section 48 be cemented together as is indicated at 22 thereby to hold strips 18 closely against the leaves of hinge section 48. It will be understood that this hinge strip will embrace the hinged edge of the folded sheet, booklet or other material to be covered and that no fastening means need be used to hold it to the material since friction and the close fitting dimensions of the protectors will serve to hold it detachably in assembled position.
It is also pointed out that the plastic material preferably used in making the protectors of this invention has a pronounced characteristic for acquiring and retaining an electrostatic charge when rubbed lightly with the hand or with a dry cloth. This charge is then highly effective in holding the plastic firmly adherent to itself and particularly to an intervening sheet of paper or the like.
. 7 The composite assembly then exhibits properties of a laminated assembly, as is highly desirable.
While the particular plastic protectors for sheet material, book and magazine covers, and the like herein shown and disclosed in detail are fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.
1. A readily removable cover protector for pamphlets, file folders and the like comprising a mounting strip adapted to be secured to the hinged edge of the cover to be protected with the exposed free edge of said strip parallel and closely spaced to said hinged edge, and a onepiece flexible sheet plastic protector having a folded size slightly larger than the cover to be enclosed and protected thereby, said protector being folded back onto itself along one medial axis, one free lateral edge of said protector having a narrow portion thereof folded back on itself to provide a deep groove for receiving the free edge of said mounting strip with the adjacent outer portion of said protector lying flush against the exterior surface of said cover and the inner portion of said protector lying flush against the interior surface of said cover and substantially coextensive therewith.
2. That improvement in the protection of magazines and the like covers which comprises afiixing one lateral edge only of a doublet protector mounting strip to the cover of a magazine leaving the other edge portion of the strip parallel and closely spaced to the cover hinge, and thereafter assembling a transparent plastic doublet protector about the cover, said doublet being substantially the same size as the cover and having one lateral edge folded back onto itself to form a deep groove, inserting the free edge of said mounting strip within the deep groove for frictional retention therein to hold the outer half of said doublet against the outer surface of the cover being protected, and folding the inner half of the doublet flush against the inner surface of the cover.
3. That improvement defined in claim 2 characterized in similarly and sequentially applying a doublet protector to both the upper and the lower cover halves of the magazine.
4. That improvement defined in claim 2 characterized in that said mounting strips are of stiif material and coated with adhesive along one lateral edge portion thereof, said adhesive being effective to hold said mounting strip firmly aflixed to the magazine cover along a narrow band parallel to but spaced inwardly from the hinge of the cover.
5. That improvement defined in claim 2 characterized in that said doublet protector is of transparent material and leaves exposed therethrough all printed matter appearing on both the outer and inner surfaces of the cover while protecting both surfaces from contact and soiling by the hands of readers.
6. That improvement defined in claim 2 characterized in that said doublet protector has a slot in the folded edge thereof embracing the free edge of the magazine cover, applying an indexing unit having an index tab astride the edge of the magazine cover; inserting said projecting index tab through said slot, and holding said indexing unit in position astride the edge of said cover by portions thereof extending in opposite directions beyond the ends of said slot.
7. That improvement defined in claim 2 characterized in that said doublet protector is formed of thin plastic material having the property of acquiring and retaining an electrostatic charge by rubbing the surface thereof, and utilizing said static charge to hold said protector closely and firmly adherent to sheet material in direct cont-act therewith.
8. That improvement in protecting drawings, data sheets and the like, said improvement comprising folding the sheet to be protected in half to provide a transverse medial hinge, securing similar strips of gummed mounting strips along one lateral half only to the exterior of said folded sheet along bands parallel to but spaced in- Wardly from said hinge and with the free edges of said strip close to and substantially coextensive with said hinge, and thereafter assembling separate transparent plastic protectors to the two halves of said sheet material, said protectors being of the folder type having one lateral edge turned back on itself to form a deep groove, the free edge of said gummed strips being seated in the deep groove of each protector and the remainder of said protector embracing and enclosing separate halves of said folded sheet material.
9. Removable and reusable protectors for sheet material folded along a transverse median axis, said protectors comprising a pair of identical plastic doublets formed in one piece and folded along a median hinge axis and having one lateral edge of one sheet folded back on itself to provide a deep groove, and a hinged connector for said pair of doublets, said connector being W-shaped in cross-section, and the free ends of the outer legs of said connector being seatable within the said deep grooves of said doublets to cooperate therewith to provide a protective enclosure for sheet material hinged along its transverse medial axis and having a folded width substantially that of said doublets.
10. A hinged connector for a pair of similar protector doublets for assembly about the respective corners of a magazine or the like, said connector being of W-shape in cross-section with its two outer legs being adapted to be seated with the turned back lateral edges of the respective protector doublets, and the binding edge of the magazine being nestable with the center V-shaped recess of said W-shaped connector.
11. An article of manufacture comprising a hinge assembly for use in holding a pair of similar doublet cover protectors assembled to the covers of a magazine, booklet, singly folded drawing and the like, said hinge assembly comprising an elongated strip of stiff but bendable material of W-shape in cross section, the apex interconnecting the two adjacent inner legs of said strip forming a hinge section adapted to embrace the hinging portion of material to be protected by said doublet cover protectors, and the two outer legs of said strip being adapted to be inserted in oomplementally shaped seating grooves therefor of said doublet cover protectors.
12. An article of manufacture for use in detachably holding a flexible plastic protector to sheet material, which protector is of the type having a narrow mounting strip integral with one lateral edge of the protector and lying closely against one surface thereof, said article comprising an elongated strip of stiff material having a narrow strip of bonding material adherent to one edge portion thereof, said bonding material being effective in securing said strip to sheet material and lying flush thereagainst with the unbonded free edge of said strip cooperating with the sheet material to provide a groove adapted to seat the mounting strip of a plastic protector.
13. An article of manufacture as defined in claim 12 characterized in that said bonding material comprises a thin layer of pressure-sensitive adhesive, and a guard strip temporarily and lightly attached to the outer surface of said adhesive, said guard strip having a pull tab extending laterally beyond said adhesive and by which said strip can be grasped and readily separated from said adhesive prior to the application of the article of manufacture to sheet material.
14. An article of manufacture suitable for use in protecting drawings, photos and the like comprising a folder creased along its medial axis, means disposed closely adjacent and parallel to said crease providing a pair of retaining grooves on the exterior surface of said folder,
and a pair of similar doublet protectors of thin sheet plastic material adapted to be assembled to each half of said folder, each doublet having a folded-over strip along one lateral edge adapted to fit into and be frictionally retained in one of said retainer grooves, and the inner half of said doublet being folded against the interior surface of the associated folder half.
15. The article of manufacture defined in claim 14 characterized in that at least one of said grooves is formed by a strip of material adhesively attached to the outer surface of said folder along the inner edge only of said strip, the outer edge of said strip adjacent said folder crease being free and unattached and cooperating with the juxtaposed folder surface in forming said retainer groove.
References Cited in the file of this patent UNITED STATES PATENTS 2,114,944 Thomas Apr. 19, 1938 2,260,407 Schade Oct. 28, 1941 3,009,465 Smith Nov. 21, 1961 FOREIGN PATENTS 110,143 Australia Mar. 14, 1940 690,550 Great Britain Apr. 22, 1953