Method for attaching web to a spool and resulting spooled web

Abstract: A method of attaching film web 10 having a remaining portion 12 and a trailing end portion 18 to a spool 24. The method of attachment comprise forming a necked down portion 20 terminating in an axially extending flap 22 on trailing end portion 18 of film web 10. Forming an adhesive member 34 comprising a central portion 36 for securely attaching to a seat 32 on elongated core 26 of spool 24, a first end portion 38 for securely attaching to one side of trailing end portion 18 of film web 10 such that first end portion 38 does not extend beyond necked down portion 20, and a second end portion 40 for securely attaching to the opposite side of said trailing end portion 18 beyond necked down portion 20 on non-image area 16 of film web 10. Flexibly attaching adhesive member 34 to spool 24 and film web 10. Finally, wrapping remaining portion 12 of film web 10 onto the edges of shoulders 28,30 of elongated core 26 so that remaining portion 12 of film web 10 overlies remaining portions 10 wrapped on shoulders 28,30 and trailing end portion 18 sandwiched between adhesive member 34 wraps onto seat 32 on elongated core 26 overlying adhesive member 34 wrapped onto seat 32. The photographic film roll 42 assembled in accordance with this method has a high attachment strength with low attachment strength variability and pressure marks are not present in the remaining portion 12 of the film roll 42.

Description: FIELD OF THE INVENTION This invention relates generally to attaching webs to spools and, more particularly, to attaching photographic film web using an improved film to spool attachment and a method for making such an attachment. BACKGROUND OF THE INVENTION Many methods and structures are known for attaching the end of a web to a spool or hub upon which the web is wound. These methods have the following known disadvantages: (1) they require intricate parts in addition to the web such as spring clips for releasably securing the web end to the hub; (2) they present a difficult assembly problem necessitating special equipment for releasably securing the end of the web to the hub; or, (3) they are complicated and expensive manufacturing methods. Moreover, in some instances the fastening methods and photographic film assembled thereby are not as reliable or dependable as desired, resulting in the web being prematurely released from the hub. Also, in film web which is attached with tape to a spool, objectionable pressure marks across the film have been known to occur during spooling because the successive convolutions of the film are deformed as they pass over the ridge formed by the attachment tape. A conventional automatic web winding equipment including a process of forming a tape portion and affixing it to the web and a spool automatically are disclosed in U.S. Patent Nos. 2,940,232 and 4,903,907. Although only sometimes do pressure marks occur in the image area of film, experience indicates that any scratches or marks in the image area may result in crystallization of the silver halide constituent and consequently marring of exposure frames. Some photographers may, however, notice the pressure marks in a non-image area of the film and be concerned that some pressure marks also have occurred in the image area. A further disadvantage of tape attachment of photographic film is that the attachment sometimes has low and variable strength which is attributed to shear separation of the tape from the film. For example, attachment strength of 35 mm film is generally known to vary between 2 kp and about 12,5 kp (10 to 60 pounds). In manufacturing, film rolls with low attachment strength tend to be difficult to spool. Moreover, low attachment strength film may result in inadvertent separation of film from the spool by the film user. U.S. Patent No. 3,021,085 discloses a method of attaching a film web to a hub having a recess fastening means for receiving the tapered end of the film web. Means for preventing pressure marks in the exposure portion of the film are not taught or suggested. US-A-4,852,821 discloses a method of attaching a web to a spool as well as a photographic film roll in accordance with the pre-characterizing portions of claims 1 and 7, respectively. SUMMARY OF THE INVENTION It is, therefore, an object of the invention to provide a method of attaching a web to a hub or spool that produces superior attachment strength. Another object of the invention is to provide a method of attaching 35 mm photographic film web to a spool such that pressure marks in the film are eliminated. Yet another object of the invention is to provide a photographic film roll with superior film to spool attachment strength. Still another object of the invention is to provide a film roll wherein attachment strength variability has been eliminated by a tape to tape bond. The method according to the present invention to solve the above stated technical problems is described in claim 1. A photographic film roll obtained by applying the method of the invention is described in claim 6. Accordingly, an important advantage of the invention is that pressure marks are not introduced in the remaining portion of the web because of the spatial separation of the remaining portion wrapped onto the shoulders of the core from the adhesive member and trailing end portion wrapped onto the core of the spool. Another important advantage of the invention is it results in a photographic film roll having low variability in the web to spool attachment strength. BRIEF DESCRIPTION OF THE DRAWING The foregoing as well as other objects, features and advantages of this invention will become more apparent from the following detailed description when taken in conjunction with the appended figures in which Figure 1 shows a fragmentary plan view of the trailing end portion of a film web having the necked-down portion with an outwardly extending transverse or T-shaped flap; Figure 2 shows an elevation view of a spool having shoulders for supporting the edges of the film web; Figure 3 shows a perspective view, partially broken away, of the adhesive member attached to the trailing end portion and the spool; Figure 4 shows a perspective view in partial section of the film web exposure portion riding on the shoulders of the spool and spatially separated from the adhesive member on the trailing end portion; Figure 5 shows a diagrammatical view of a photographic film roll constructed in accordance with the present invention; Figure 6 shows a section along line 6-6 of Figure 5; and, Figure 7 is an enlarged fragmentary view of the film roll of Figure 6 showing a web portion on the shoulders and tape portion on the core portion of the spool. DETAILED DESCRIPTION OF THE DRAWING Turning now to the drawings, and more particularly to Figure 1 there is shown a fragmentary plan view of film web 10 of the present invention having a remaining portion 12 comprising an image area 14 and a non-image area 16 and, a trailing end portion 18. The image area 14 comprises exposure frames (not shown). The trailing end portion 18 has a centrally located, axially extending symmetrical necked-down portion 20 terminating in an outwardly extended transverse or T-shaped flap 22. Axial length L of the trailing end portion 18 is preferably 0,762 cm (o,300 inches). For 35 mm photographic film, necked-down portion 18 has a thickness (t) in the range of 0,635 to 1,778 cm (o,25 to 0,70 inches), although 1,397 cm (0,550 inches) is preferable. The thickness (t') of T-shaped flap 22 is preferably between 0,127 to 0,254 cm (0,050 to 0,100 inches). The T-shaped flap 22 is preferred because it enables greater attachment strength and lower attachment strength variability as further described below. The T-shaped flap 22 also adds the required flexibility to web 10 during the spooling process. Other geometries for the axially extending flap 22 are also within the scope of the invention, such as an axially extending rectangular tab. The T-shaped flap 22 of the present invention or other suitable configuration, may be die cut, although those skilled in the art would readily recognize that other means for forming T-shaped flap 22, such as laser cutting, may be employed. Turning next to Figure 2, a 35 mm spool 24 for receiving a film web 10 is shown comprising an elongated core 26 bounded on either end by shoulders 28,30 of larger diameter than the elongated core 26. The enlarged shoulders 28,30 support the edges of remaining portion 12 of film web 10 (see Fig. 1) during spooling and form therebetween a seat 32 on elongated core 26 for receiving trailing end portion 18 of film web 10. The spool 24 is preferably plastic, although any suitable material, such as metal, may also be used. As shown in Figure 3, an adhesive member 34, comprising a central portion 36, a first end portion 38 and a second end portion 40 is formed having a width less than both remaining portion 12 of film web 10 and seat 32, and greater than necked-down portion 20 and T-shaped flap 22 on trailing end portion 18 of film web 10. Preferably, adhesive member 34 is a pressure sensitive tape made of a latex impregnated paper material. The tape has an attachment strength of at least 44 N (10 lbs), although greater than about 89 N (20 lbs) is preferable. T-shaped flap 22 enables film web 10 to spool 24 attachment strength to be limited by bonding of overlying adhesive member 34 and not by the relatively weak film web 10 to adhesive member 34 bonding forces as indicated by experiments. According to the test, the bonding of overlying adhesive member 34 on core 36 of spool 24 initiates at necked-down portion 20 as T-shaped flap 22 is trapped between necked down portion 22 and core 26. Film web 10 to spool 24 attachment strength is measured using the ANSI dynamic test method (PH1.14M -1983) which requires a tensile tester with a cross head speed of approximately 10 cm/min (4 inches/minute). Tape attachment strength of this magnitude has been experimentally determined to insure good tape adherence to spool 24 and overall improved film web 10 attachment strength. The adhesive member 34 is shown in Figure 3 with first end portion 38 secured to one edge of one side of necked-down portion 20 of film web 10. The first end portion 38, shown clearly in Figure 3, does not extend beyond the edge of T-shaped flap 22 onto remaining portion 12 of film web 10. Experiments indicate that film web 10 buckling occurs when first end portion 38 extends beyond the edge of T-shaped flap 22 onto remaining portion 12 of film web 10. Moreover, ridges of adhesive member 34 result from over extending first end portion 38 beyond T-shaped flap 22. These ridges are known to produce pressure marks in film web 10 during spooling. The central portion 36 of adhesive member 34 is shown wrapped around seat 32 of spool 24 and second end portion 40 of adhesive member 34 securely attached to the opposite side of trailing end portion 18 on non-image area 16 of film web 10. In conventional film web spooling machines, such as described in U.S. Patent No. 2,940,232, the tape is pulled from a roll by a measuring device, and is held on a vacuum box and chopped off to length. The vacuum box is then pivoted to apply the tape to the core of a film spool. Thus, a preferred method of attaching a film web 10 to a hub or spool 24, both as described above, in accordance with the present invention comprises the steps of: forming an axially extending necked-down portion 20 terminating in an outwardly extended T-shaped flap 22 in trailing end portion 18 of film web 10 (as shown in Figure 1); forming an adhesive member 34 comprising a central portion 36, and first and second end portions 38,40, adhesive member 34 also having a width less than seat 32 of elongated core 26 and remaining portion 12 of film web 10 and wider than necked-down portion 20 of film web 10 and T-shaped flap 22 (as shown clearly in Figure 3); flexibly attaching adhesive member 34 to elongated core 26 of spool 24 such that first end portion 38 securely attaches to the edge of T-shaped flap 22 and does not extend beyond T-shaped flap 22 onto remaining portion 12 of film web 10, central portion 36 wraps at least partially around elongated core 26, and second end portion 40 attaches securely to the opposite side of necked-down portion 20 beyond T-shaped flap 22 on non-image area 16 of film web 10(shown more clearly in Figure 3); and wrapping remaining portion 12 of film web 10 around the edge of shoulders 28,30 of elongated core 26 spaced-apart from adhesive member 34, as shown in Figure 5, so that image area 14 of film web 10 and adhesive member 34 do not come into frictional contact. In this embodiment, adhesive member 34 overlies only adhesive member 34 on elongated core 26 of spool 24 and not image area 14 of film web 10 which rides on shoulders 28,30 of spool 24. Figure 6, a section view taken along the 5-5 line of Figure 5, shows more clearly central portion 36 of adhesive member 34 wound onto elongated core 26 of spool 24 and T shaped flap 22 on trailing end portion 18 sandwiched between first and second end portions 38,40 of adhesive member 34. In Figure 7, an enlarged fragmentary view of a portion of Figure 6, shows T-shaped flap 22 sandwiched between first and second portions 38, 40 of adhesive member 34. First end portion 38 is shown extended to the edge of T-shaped flap 22 and not onto remaining portion 12 of film web 10. Experiments indicate that much needed flexibility is imparted to film web 10 by this latter arrangement and film web 10 buckling does not occur during spooling. Thus, the first convolution of film web 10 comprising image area 14 is shown in Figure 6 ( and an enlarged view in Figure 7) separated from the core 26 and wound onto shoulder member 28 of spool 24. In this way, ridges of adhesive member 34 cannot easily interfere with film web 10 wrapped around shoulders 28,30 of spool 24 causing pressure marks therein. Thus, a preferred embodiment of a photographic film roll 42 of the present invention, as shown in Figure 4, comprises: a spool 24, as described above; a film web 10, as described above; an adhesive member 34, as described above, wherein first end portion 38 securely attaches to the outer edge of one side of T-shaped flap 22 (shown clearly in Figure 3), central portion 36 wraps around seat 32 of elongated core 26 and second end portion 40 securely attaches to the opposite side of T-shaped flap 22 on non-image area 16 of remaining portion 12 of film web 10; and, wherein image area 14 of remaining portion 12 of film web 10 wraps around shoulders 28,30 of spool 24 spaced-apart from adhesive member 34 so that adhesive member 34 and image area 14 do not come into frictional contact, as shown more clearly in Figure 5. The attachment strength, measured in the manner described above, of photographic film roll 42 of the present invention varies within the narrow range of from about 142 N to 169 N (32 to 38 pounds). Moreover, in accordance with another embodiment of the invention, it is provided a method of reducing pressure marks on the surface of a film web 10 attachable to a spool 24, both described above, the method comprising the steps of : forming an axially extending necked-down portion 20 terminating in an outwardly extended, centrally located, symmetrical T-shaped flap 22 in trailing end portion 18 of film web 10 as shown in Figure 1; forming an adhesive member 34, as described above, having a width less than both remaining portion 12 of film web 10 and seat 32 and wider than necked-down portion 20 and T-shaped flap 22 of film web 10; flexibly attaching adhesive member 34 to elongated core 26 of spool 24 such that first end portion 38 securely attaches to the edge of T-shaped flap 22 and does not extend beyond T-shaped flap 22 onto remaining portion 12 of film web 10, central portion 36 wraps at least partially around elongated core 26 of spool 24, and second end portion 40 attaches securely to the opposite side of necked-down portion 20 beyond T-shaped flap 22 on non-image area 16 of film web 10 (shown more clearly in Figure 3); and wrapping remaining portion 12 of film web 10 around the edge of shoulders 28,30 of elongated core 26 spaced-apart from adhesive member 34 so that image area 14 of remaining portion 12 and adhesive member 34 do not come into frictional contact as shown in Figure 5.

Claims: A method of attaching a web (10) having a trailing end portion (18) and a remaining portion (12) to a spool (24) having a core (26) and shoulders (28, 30) on either end of said core for separating web portions on said core from web portions on said shoulders (28, 30), said remaining portion (12) having an image area (14) and a non-image area (16), said shoulders (28, 30) having diameters greater than the diameter of the spool core (26), comprising the steps of: a) forming an axially extending flap (22) on said trailing end portion (18) of said web (10), said flap (22) being narrower than said web (10) and narrower than the distance between said shoulders (28, 30), b) wrapping said remaining portion (12) of said web (10) onto the edges of said shoulders (28, 30) of said core (26) so that said remaining portion (12) of said web (10) overlies remaining portions wrapped on said shoulders (28, 30), characterized by performing, between steps a) and b), the steps of: c) forming an adhesive member (34) comprising a central portion (36) for attaching to said core (26) of said spool (24), a first end portion (38) for attaching to one side of said trailing end portion (18) such that said first end portion (38) attaches to said flap (22) and does not extend beyond said trailing end portion (18), and a second end portion (40) for attaching to the opposite side of said trailing end portion (18) on said remaining portion (12) of said web (10) such that said second end portion (40) extends beyond said trailing end portion (18) on said non-image area (16) of said remaining portion (12), the width of said adhesive member (34) being narrower than the distance between said shoulders (28, 30), and d) flexibly attaching said adhesive member (34) to said spool (24) and said web (10), wherein, in step b), said trailing end portion (18) sandwiched between said adhesive member (34) wraps onto said core (26) overlying said adhesive member (34) wrapped onto said core (26). The method recited in claim 1 wherein said axially extending flap (22) is symmetrical with respect to the longitudinal axis of the web and centrally located on said trailing end portion (18). The method recited in claims 1 or 2 wherein said axially extending flap (22) is an outwardly extended T-shaped flap. The method recited in one of the preceding claims wherein a necked-down portion (20) of said trailing end portion (18) has a thickness from about 0,635 cm (0,25 inches) to about 1,778 cm (0,7 inches). The method recited in claim 4 wherein said necked-down portion has a thickness of 1,397 cm (0,550 inches). A photographic film roll comprising: a) a spool (24) comprising an elongated core (26) portion bounded by a pair of shoulders (28, 30), said shoulders and said elongated core forming a seat (32) therebetween, and wherein the diameter of each of said shoulders (28, 30) is greater than the diameter of said elongated core (26) portion; b) a film web (10) comprising a remaining portion (12) having an image area (14) and a non-image area (16) and a trailing end portion (18), characterized in that c) said trailing end portion (18) has a necked-down portion (20) terminating in an axially extending flap (22), said axially extending flap (22) having a width greater than said necked-down portion (20) and of less width than said remaining portion (12); d) an adhesive member (34) is provided comprising first and second end portions (38, 40) and a central portion (36), said adhesive member (34) having a width less than both the width of said remaining portion (12) and said seat (32) and greater than said axially extending flap (22); e) said first end portion (38) of said adhesive member (34) is securely attached to one side of said necked-down portion (20) such that said first end portion (38) does not extend beyond said necked-down portion (20) onto said remaining portion (12) of said film web (10), said central portion (36) of said adhesive member (34) wraps around said seat (32) of said spool (24) and, said second end portion (40) securely attaches to the opposite side of said necked-down portion (20) such that said second end portion (40) extends beyond said trailing end portion (18) in said non-image area of said remaining portion but does not extend onto said image area (14) of said web (10) thereby adhesively joining said film web (10) flexibly to said spool (24); and in that f) said trailing end portion (18) sandwiched between said adhesive member (34) wraps onto said core (26) and said remaining portion (12) of said film web (10) is wound onto said shoulders (28, 30) of said spool (24) spaced-apart from said adhesive member (34) so that said remaining portion (12) and adhesive member (34) do not come into frictional contact. The photographic film roll recited in claim 6 wherein said necked-down portion (20) of said film web (10) has a thickness from about 0,635 cm (0,25 inches) to about 1,778 cm (0,70 inches). The photographic film roll recited in claim 6 wherein said necked-down portion (20) of said film web (10) has a thickness of 1,397 cm (0,550 inches).

Inventors: RITCHIE SHAWN W, RITCHIE, SHAWN W., Ritchie, Shawn W., c/o Eastman Kodak Company
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1992
Main classification: G03B21
IPC codes: G03C1, G03C3, G03B17