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Induction splicing of photographic film strips

a technology of induction splicing and photographic film, which is applied in the direction of photosensitive materials, instruments, transportation and packaging, etc., can solve the problems of insufficient solvent soluble polymer used as the support base, cumbersome splicing technique, and inability to bind to the substrate,

Inactive Publication Date: 2005-05-19
EASTMAN KODAK CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This method produces splices with tensile strength comparable to traditional cement and ultrasonic splices, while being smoother and eliminating the use of hazardous materials, allowing for successful splicing of both similar and dissimilar film types without damaging adjacent film areas.

Problems solved by technology

Because a cement splice does not attain full strength for several hours, care is required when handling the film if immediate use is contemplated.
Not only is this splicing technique cumbersome, time consuming, and a source of debris, but there are also health, safety and environmental concerns surrounding the components of the currently employed film cements.
With the advent of PET-based film products, a new splicing technique was required since this film support does not readily lend itself to cement splicing.
The polymer used as the support base is not soluble in the solvents used in film cement and even more toxic solvents would be required to produce the same type of bonding with PET-based films.
These tapes are costly, cumbersome, a potential source of dirt and require application to imaged frames adjacent to the splice itself.
While the use of ultrasonic welding techniques has been suggested for splicing of acetate based film strips, attempts to do so have generally not been successful.
Motion picture film splicers that have been developed which utilize ultrasonic energy to splice PET-based films together, e.g., when used to splice CTA-based films, cause brittleness and diminished strength typically resulting in splices that are far too weak and / or rough for practical application.
Such splices may exhibit levels of roughness that are likely to damage adjacent areas of film when wound in roll form.
To date no one has provided a method for successfully splicing together motion picture film strips composed of dissimilar polymeric supports that does not rely on the use of pressure-sensitive tape.
The prior art has also failed to provide a method of splicing cellulosic-based motion picture film without the need for removal of the emulsion layer and application of a flammable and toxic solvent mixture.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0041] A bonding element was prepared by coating thermoplastic adhesive material (VITEL™ 3300B, produced by Bostik) onto each side of standard food-grade aluminum foil from Alcoa (REYNOLDS WRAP™), which is approximately 18 μm in thickness. VITEL™ 3300B is a high molecular weight, aromatic, linear saturated polyester resin having a glass transition temperature of 11° C. and a (Ring and Ball) melt flow point of 125° C. The adhesive was applied from a 30% solution in 2-butanone. The coatings were dried for 15 minutes at 65° C. Dried coating thickness was estimated to be approximately 6 μm on either side of the foil.

[0042] Pieces of coated foil were cut 2 mm wide by 35 mm long to form film strip bonding elements, and sandwiched between overlapping ends of strips of 5234 and 2234 films. Splices were prepared by positioning the bonding element internal to the overlapped film components, clamping the assembly directly over an induction coil, initiating the sealing cycle (0.5 seconds impul...

example 2

[0044] Splice samples were prepared similarly as in Example 1 using different films, film combinations, and orientations and measured for tensile strength. The bonding element and sealing parameters are the same as noted in Example 1. The resulting tensile strength averages are shown in Table 1. In Table 1, the film listed first is the upper member of the splice; therefore the backside of this film is bonded to the emulsion side of the lower film member.

TABLE 1Film codesTensil Strength (kg)2383 / 238312.85279 / 527913.32383 / 527910.05279 / 238318.52234 / 223412.55234 / 523411.52234 / 523411.75234 / 223410.8Aim15.05234 Cement check13.62234 Ultrasonic check10.4

Most of the combinations, independent of film type or orientation, exhibit a tensile strength of 10-13 kilograms, which is comparable to the ultrasonic and cement splice checks and therefore considered adequate for practical application. It is demonstrated that similar or dissimilar films can be spliced in any configuration or orientation a...

example 3

[0045] VITEL™ 3300B adhesive was applied to a polyethylene terephthalate (PET) support that had been vacuum-metalized with a thin layer of silver. The adhesive was coated on the silver surface at a dry thickness of approximately 6 μm. This material proved to be very receptive to induction heating, but at the impulse time and power levels previously employed (0.5 seconds and 70% respectively), the film has a tendency to char. For this sample only, the backside of 2234 acetate based film was bonded to a sample of the metal layer and adhesive coated PET support by induction heating similarly as in Example 1, but with the power reduced to 30% and the impulse time increased to 2.0 seconds. The peel strength of the adhesive coated surface to the backside of 2234 film averaged 4 kg / 35 mm width, well above the aim strength.

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Abstract

A method is described for splicing together overlapping ends of first and second lengths of photographic film strips of common film strip width, comprising positioning a bonding element between an overlapping end of the first length of photographic film and a corresponding overlapped end of the second length of photographic film, and heating the bonding element to effect an adhesive bond between such film ends, wherein the bonding element comprises an induction heating receptive support and thermoplastic adhesive layers on each side of the support, and wherein the heating of the bonding element is performed by induction heating. The present invention allows for the preparation of photographic film splices, consisting of either homogeneous or dissimilar film bases, using a bonding element and induction heating to provide smooth yet strong splices. In particular, the invention enables successful splicing of acetate support (e.g., cellulose triacetate (CTA)) based films and polyester support (e.g., polyethylene terephthalate (PET)) based films either to themselves or each other. The invention provides a method of forming composite rolls of motion picture film containing different film bases as well as eliminating the need for emulsion skiving, and the use of toxic, flammable film cements when splicing CTA films.

Description

FIELD OF THE INVENTION [0001] This invention relates to a method of utilizing induction-heating technology to splice together photographic film strips, and especially motion picture films having dissimilar polymeric supports. In particular, the invention relates to materials and methods that will allow successful splicing of acetate support (e.g., cellulose triacetate (CTA)) based films and polyester support (e.g., polyethylene terephthalate (PET)) based films either to themselves or to each other. BACKGROUND OF THE INVENTION [0002] Motion picture photographic films used in producing a release print (the film projected in movie theaters) include camera origination film, intermediate film, and the release print film. Current practice for most motion picture production involves the use of at least four photographic steps. The first step is the recording of the scene onto a camera negative photographic film. While the original negative (typically after editing) may be printed directly ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G03D15/04
CPCY10T428/19G03D15/043
Inventor SMITH, THOMAS M.JOHNSTON, BRIAN H.DONTULA, NARASIMHARAOKORDOVSKI, LUBA
Owner EASTMAN KODAK CO