US3503526A

US3503526A - Web handling apparatus and process

Info

Publication number: US3503526A
Application number: US656432A
Authority: US
Inventors: James Richmond Crafton
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1967-07-27
Filing date: 1967-07-27
Publication date: 1970-03-31
Anticipated expiration: 1987-03-31
Also published as: DE6750784U

Description

March 31, 1970 J. R.

GRAFTON

3,5

1 WEB HANDLING APPARATUS AND PROCESS Filed July 27. 1967 INVENTOR JAMES RICHMOND CRAF T0l| BY 1:, 73M 74m.-

ATTORNEY United States Patent 3,503,526 WEB HANDLING APPARATUS AND PROCESS James Richmond Crafton, Hendersonville, N.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed July 27, 1967, Ser. No. 656,432 Int. Cl. B65h 17/18; Hf N02 US. Cl. 242-55 7 Claims ABSTRACT OF THE DISCLOSURE An apparatus for winding or unwinding continuous webs of non-conductive material, the appartus incorporating an alpha particle-emitting device directed toward a winding or unwinding roll of web beyond the point of tangency between the web and roll.

BACKGROUND OF THE INVENTION Field of the invention Description of the prior art The prior art teaches the use of gas flames, X-rays, cathode rays, high-potential electrical sources, and various radioactive sources as means of ionizing the air surrounding them for the purpose of destaticizing electrically non conductive surfaces. However, the prior art expressly discloses or implies that the surface to be electrically neutralized be in the immediate vicinity of the ionizing source, i.e., within a few inches from the alpha particle sources that have been proposed for use adjacent a nip between a web and roll.

It has been found that if an alpha particle-emitting device is directed onto a web before it is wound, the average electrostatic charge on the wound roll is much greater than if the device is directed onto the web on the roll after the point of tangency. The difference is manifold, which is quite unexpected. Similar results are obtained during unwinding with the apparatus described herein.

SUMMARY OF THE INVENTION The apparatus of the invention comprises a rotating roll of web of non-conductive material 'having in combination therewith adjacent the roll beyond the point of tangency between the moving web and the roll an alpha particle emitting device directing particles toward the roll of web. One or more alpha particle emitting bars which extend across the width of the web can be used. The invention also comprises a process as described above.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric view of one form of apparatus of the invention, and

FIG. 2 is an elevation of a multiple yoke winding apparatus of the invention.

Referring to FIG. 1, a web W which is being wound on a suitable core (not shown) mounted on suitable

vertical supports

1 and 2 attached to base 3. The apparatus ice has an alpha particle emitting bar 4 which extends across the roll. The bar is approximately 45 from the point of tangency between the web and the surface of the roll. The ends of the bar are fastened by suitable means to arms 5 and 6 which extend laterally from and are attached to the vertical supports.

In FIG. 2, the web handling device comprises multiple yokes 10 which are attached to the ends of a suitable rotatable hub or shaft 11 that can be journalled in any suitable support frame (not shown). The ends of the three radial arms are adapted to support respective roll cores or spindles 12-, 13 and 14. A roll of web W is shown as being wound onto core 14 while a fully wound roll is shown on core 12 and is in position for removal. Core 13 has been placed on the remaining arm and upon rotation of the yoke can be brought into winding or unwinding position as is common in the art of winding and unwinding webs. Alpha

particle emitting bars

15, 16 and 17 are placed adjacent the hub or shaft of the yokes.

The web passes from a suitable source (not shown) which in the case of photographic film or paper could be from an emulsion coating apparatus or a drying apparatus. It passes over

guide rollers

18 and 19 and between the yokes so that they extend across the width of the web. The bars emit alpha particles so that an ion cloud is formed in the atmosphere adjacent the roll of web and remove static charges on each lap of the web as it is wound onto the web.

For comparison, as described below, alpha

particle emitting bars

20 and 21 are shown close to the web before it is in the form of a web roll.

It has been found that good results can be obtained when the bar or bars are spaced 5 to 14 inches from the surface of the roll of web.

The table below indicates the effectiveness of applicants construction when incorporated in a rewind apparatus as shown in FIG. 2, which is winding a clear polyethylene terephthalate web.

The measurements of electrostatic charge level were made with a transducer which converts the electrostatic signal into an A-C signal, which is measured by a standard A-C voltmeter. The transducer was held approximately one inch from the roll surface and measurements were taken at three points across the width of the web, every one thousand feet of web wound. During the course of the experiment the rotational speed of the winding roll varied from approximately 20 to 55 r.p.m.

Average electrostatic ch arge on roll #13 -

Emitters

15 and 16* were taped to prevent emission. Emitter 17 was moved to position 21, approx. 2 in. from the web, near idler roll 19.

Emitters

15, 16, 17 were placed as shown in Fig. 2 and all were operating. Generator to winding roll distance varied from 14-5 inches.

Same as Expt. #1, except emitter 17 was moved to position 20, approximately 3 in. from the web, 3 it. from winding nip point.

Emitters

15, 16, 17, all mounted in position 20, approximately 3 inches from the web, 3 ft. from winding nip point.

Same as Expt. #2 except

emitters

15 and 16 were taped to prevent emission.

Emitters

15, 16, and 17, all mounted in approximately position 17 in Fig. #2 and all directed toward roll 14.

'I he alpha particle emitters used in this experiment were 3M Brand Static Eliminators, Model 7B8F, 1% millicuries/in. activity.

The above table indicates that in the three cases (2, 5 and 6) where the alpha particle emitter was in a position to create an ion cloud adjacent the winding roll the electrostatic charge build-up was lower than when the alpha particle emitter was directed at the web alone before the web was wound onto the winding roll. When no alpha particle emitters were used either on winding roll or the web alone, the electrostatic charge on the Wind ing roll rapidly built up to the saturation point of approximately 25 kv., within 100 to 20 feet of web wound.

Preferably the bar is placed around the roll a substantial distance from the point of tangency and from the nip between the roll and Web.

The process and apparatus of the invention can be used with various webs of non-conductive material such as paper, resin coated, e. g., polyethylene coated paper, cellulose derivative, e.g., cellulose acetate, cellulose acetate propionate and cellulose acetate butyrate polystyrene, polyvinyl acetate and polyester, e.g., polyethylene terephthalate. Such webs accumulate static charges. These webs can, of course, be coated with various layers, e.g., vinylidene chloride copolymer layers and/or various photographic layers. For example, the invention can be used with high speed negative photographic films provided the web is in motion during passage by the bars. A safe residence time for such a photographic film in the field of a 1.5 anillicurie/inch alpha particle emitting bar is 4. A process which comprises windinga web of nonapproximately 30 seconds at a web generator distance of 2 inches.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A web winding apparatus comprising spaced yokes having a plurality of radial arms adapted to support rotatable rolls of non-conductive web material, said yokes being mounted on a hub extending between the yokes, an alpha particle emitting bar mounted on the hub adjacent each roll of web, and disposed so as to emit particles toward the axis of the respective roll.

2. A web winding apparatus according to claim 1 wherein there are three equally spaced radial arms.

3. A web winding apparatus according to claim 1 wherein there are three equally spaced radial arms and 1 into a roll, directing alpha particles onto the outer convolution of the roll as it rotates, the particles emanating from a source 5-14 inches from said convolution and being directed to an area around the roll a substantial distance from the point of tangency between the Web and the roll.

5. A process which comprises winding a web of nonconductive web material that accumulates static charges into a roll, directing alpha particles onto the outer convolution of the roll as it rotates, the particles emanating from a source 514 inches from said convolution and being directed to an area around the roll a substantial distance from the point of tangency between the weband the roll, and a substantial distance from the nip between the web and roll.

6. A process according to claim 5 wherein the particles are directed from a source extending across the width of the roll.

7. A process according to claim 5 wherein said Web is a polyethylene terephthalate web.

References Cited UNITED STATES PATENTS 2,048,490 7/ 1936 Bilstein.

2,479,882 8/1949 Wallhausen et a1. 3l7-2 X 3,392,311 7/1968 Goetemann 3172 3,396,917 8/1968 Carter 242- OTHER REFERENCES Metal Progress, vol. 62, N0. 5, November 1952, pp. 9496.

STANLEY N. GILREATH, Primary Examiner WERNER H. SCHROEDER, Assistant Examiner US. Cl. X.R. 3172