US3807052A

US3807052A - Apparatus for irradiation of a moving product in an inert atmosphere

Info

Publication number: US3807052A
Application number: US00266121A
Authority: US
Inventors: H Troue
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1972-06-26
Filing date: 1972-06-26
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: DE2332116A1; IT985782B; NO149060B; JPS5226254B2; CA1016898A; NO149060C; ZA733244B; DK150968B; AU474766B2; FR2190513A1; SU580807A3; GB1434996A; BE801412A; DE2332116C3; DK150968C; JPS4992167A; DE2332116B2; AU5726473A; FR2190513B1; SE400908B

Abstract

A treatment enclosure for irradiating a moving product which passes through said enclosure comprising an open treatment chamber housing a source of radiant energy, a pair of tunnels extending longitudinally from opposite sides of the chamber and an elongated inert gas injector channel, which opens into the enclosure a distance from the inlet tunnel end of the enclosure equal to at least ten times the smallest cross sectional dimension of the tunnel opening and which lies substantially parallel to the tunnel width, for directing inert gas at the moving product.

Description

United States Patent 11 1 1111 Troue Apr. 30, 1974 54] APPARATUS FOR IRRADIATION OF A 3,364,387 1/1968 Anderson 315/111 VI G PRODUCT IN AN INERT 3,11 1,424 1 H1963 LeClair ll7/93.31 2,887,584 5/1959 Nygard 250/49.5 TE ATMOSPHERE v 2,763,609 9/1956 Lewis et al 204/159.l3 [75] Inventor: Harden Henry Trolie, Indianapolis, .7 5. 3 o ya et 313/221 1nd. 3,150,281 9/1964 Bishay 313/221 [73] Assignee: Union Carbide Corporation, New FOREIGN PATENTS OR APPLICATIONS York, N.Y. 762,953 12/1956 Great Britain 22 Filed: J ne .26 1972 1 u Primary ExaminerWil1iam F. ODea PP 1 Assistant Examiner-P. Devinsky Attorney, Agent, or FirmE. Lieberstein [52] U.S. Cl 34/1, 117/9331, 204/l59.23,

250/492 [57] ABSTRACT ll'ilt. A treatment enclosure for irradiating a i g p [58] new of Search I 34/1 9 uct which passes through said enclosure comprising an 204/159'1 1 17/9331 open treatment chamber housing a source of radiant 313/221 energy, a pair of tunnels extendinglongitudinally from opposite sides of the chamber and an elongated inert [56] References cued gas injector channel, which opens into the enclosure a UNITED STATES PATENTS distance from the inlet tunnel end of the enclosure 3,600,122 8/1971 Coleman 117/47 A equal to at least ten times the smallest cross sectional 3,683,188 8/ 1972 Hugonin 250/52 dimension of the tunnel opening and which lies sub- 3.676.67 3 7/19 Co ema 117/9331 stantially parallel to the tunnel width, for directing 3,654,459 4 1972 Coleman 117/9331 inert gas-at the moving product 3,597,650 8/1971 Anderson et al. 315/111 3,418,155 12/1968 Colvin et a1. 204/159.11 17 Claims, 12 Drawing Figures PATENTEUAPR 30 mm min u 0F 4 i i i i i i APPARATUS FOR IRRADIATION OF A MOVING PRODUCT IN AN INERT ATMOSPHERE This invention relates to apparatus for the continuous in-line irradiation treatment of the surface of a moving coated product and more particularly to such apparatus for irradiating the surface of a moving coated product in a substantially inert atmosphere.

BACKGROUND OF THE INVENTION Subjecting a cross-linkable polymeric coating to radiant energy to improve its properties, particularly the surface characteristics of the coating, has been an area of intensive study for many years. It has long been established that the effectiveness of such irradiation as well as the curing speed may be enhanced by maintaining an inert atmosphere over the surface of the coated product during the period of irradiation. This is especially true when electromagnetic energy or high energy electrons is used as the irradiating medium. Under con-- trolled laboratory conditions no difficulty is experienced in maintaining an inert atmosphere over the surface of the coated product. In fact, even in an industrial operation the principal consideration is that of operating cost due primarily to the high consumption of inert gas. It should be understood that any saving in gas consumption, when realized over a period such as a year in a substantially continuousround-the-clock operation, translates into substantially reduced operating costs which can mean commercial viability for such processes.

For commercial acceptability the irradiation operation must take place on the production line facility and therefore must be compatible with production line speeds which, depending upon the application, vary from minimum speeds of about 60 feet per minute to present maximum speeds of about 600 feet per minute. A coated product moving at line speed carries on its surface a thin film of air which must be substantially displaced by inert gas to permit effective surface curing when subjected to radiant energy. The displacement of such air must occur prior to the exposure time which is hereinafter defined as that interval of time in which a given coated product surface area is exposed to radiant energy. At a line speed of 600 ft/min. for a treatment chamber having for example, a total length of 3 feet and an irradiation length of 1 foot, the chamber residence time would be 0.3 seconds and theexposure time 0.1 seconds leaving a maximum time period of only 0.2 seconds to displace the air film on the coated product surface.

In general, for a fixed inerting chamber geometry, the faster the coated product travels through the chamber, the higher the inert gas flow rate must be into the chamber to sustain an inert atmosphere. In addition, higher traveling speeds provide reduced time to attain a settling of flow patterns in the chamber and any differential concentration of inert gas existing along the surface of the coated product, particularly a wide product, can result in a non-uniform cure. One may significantly increase the flow rate to forcibly sweep off atmospheric air which would otherwise be drawn in with the product or, alternatively reduce the traveling speed. As a practical matter however, the traveling speed is fixed by the production line speed and the inerting system must be compatible with such speed. Moreover, the commercial user of the process wants to set the gas-flow rate only once and, for economy, at as low a flow rate as possible. Furthermore, not only is the production line speed periodically varied to suit the particular application but also product size, particularly product width, varied periodically below a maximum value.

. Therefore, to satisfy commercial requirements the irradiation system must be capable of providing an acceptable uniform cure irrespective of normal production line variations in product width and product line speed preferably using a single fixedtotal flow rate. Moreover, the system should be linearly scalable in dimensions and flow requirements to permit predictable design of a unit for the uniform treatment of a product of any width and at any required line speed. Also, once the physical system dimensions have been established for a maximum product width and line speed the system should provide equal treatment of products of sub stantially reduced width dimensions and/or line speeds without alteration of the system parameters.

Two recent patented publications namely French patents 2,058,090 and 2,058,091 respectively, directly concern themselves with the present subject matter. Both patents describe various alternative designs for maintaining a relatively pure inert nitrogen atmosphere in a partially enclosed chamber through which the product passes for treatment. In the examples given the travel speed is fixed at about 180 ft./min. and the products treated are limited to no greater than 15 inches in width. In practice, the product width will depend upon the commercial application and is accordingly varied on the production line to suit such application. A product width of as much as inches is not uncommon. Although a relatively low gas flowrate is mentioned, there is no indication that the system design is linearly scalable to treat substantially wider products and/or narrower products at varying line speeds.

OBJECTS OF THE INVENTION It is therefore the primary object of the present invention to provide an apparatus for continuous in-line irradiation treatment of the coated surface of a moving product wherein 'an inert gaseous atmosphere is maintained over the coated. product surface during treatment.

It is another object of the presentinvention to provide apparatus for maintaining the surface of a moving coated product under a blanket of inert gas during irradiation treatment thereof; which apparatus is linearly scalable in terms of the inert gas flow rate required to treat any product width at any desirable speed.

It is yet a further object to provide such radiation apparatus for uniformly treating a moving coated product while under a blanket of inert gas which apparatus requires only a relatively low, substantially constant, inert gas flow rate to sustain the inert atmosphere notwithstanding normal production line variations in product width or product speed below a predetermined maximum.

DRAWINGS exit tunnels respectively;

FIG. 7 illustrates in perspective a typical apparatus operated according to the present invention;

FIG. 8 is a longitudinal section taken along lines 88 of FIG. 7; v

FIG. 9 is a side view taken along lines 99 of FIG. 8.

DETAILED DESCRIPTION OF INVENTION Static systems for maintaining an inert gaseous environment about a workarea are well known. The underlying design concept basic to all of such systems, is to establish an inert gas flow pattern which will cause the air within the work area to be displaced by the inert gas, unit volume for unit volume, without permitting the inert gas to intermix with the air. The difficulty resides in applying this rationale to a dynamic system where the coated product is in motion relative to the work area. The moving coated product tends to draw air into the work area disturbing the flow conditions and thereby creating turbulence. The problem is further accentuated in chemical irradiation processes where only a slight presence of oxygen at the coated product surface can inhibit surface curing.

FIG. 1 is a diagrammatic illustration of the assembly of the present invention. The product P which may represent a chemical coating or a coated substrate, of continuous length such as a web or of finite length such as for example a wallboard, is passed through a treatment enclosure 10 where it is exposed to electromagnetic irradiation from a radiant energy source (not shown). The radiant energy source is mounted in the radiation chamber 12 with appropriate optics (not shown) for directing the electromagnetic radiant energy at the product P as it passes relative thereto. Any source of electromagnetic radiant energy may be employed although an internally cooled or non-cooled source is preferred. If the source requires external cooling an optically transparent medium must be mounted to physically separate the irradiation zone 14 from the radiation chamber 12.

Internally cooled sources and non-cooled sources require no physical separation from the irradiation zone 14 and hence form an integral part of the treatment enclosure 10. A typical preferred internally cooled electromagnetic radiation source is a plasma arc source as described in US. Pat. Nos.'3,364,387 and 3,597,650 respectively. Typical preferrednon-cooled electromagnetic radiation sources are low pressure shortwave ultraviolet mercury tubes or germicidal lamps as disclosed in US. Pat. application Ser; No. 266,122 filed concurrently herewith in the names of C.L. Osborn and H.H. Troue and entitled Process.

The treatment enclosure 10 further includes an entrance or inlet tunnel 16, an injector channel 18 through which inert gas is passed from a plenum chamber 20, and an exit tunnel 24. Inert gas is delivered to the plenum chamber 20 from an inert gas supply (not shown). Although any inert gas may be used nitrogen is preferred.

The term tunnel for purposes of the present disclosure is defined as a hollow passageway of uniform cross-section which may either have a self-enclosed periphery or a partially enclosed periphery which becomes substantially fully enclosed when the moving coated product is present. The length of the entrance tunnel 16 as well as the length of the exit tunnel 24 should be as long as is practically permissable.

The location, geometry and orientation of the injec- I tor channel 18 is critical in achieving a non-turbulent, non-mixing inert gas flow within the treatment enclosure 10 in such a manner that a gas flow below about 500 cfh per each foot of tunnel width and preferably below about 400 cfh/ft. of tunnel width is all that is necessary to achieve a uniform inert blanket over the coated surface of the moving product irrespective of product speeds up to about 600 fpm. Moreover once a gas flow rate has been established as stated, for a given maximum tunnel width, the treatment assembly will accomodate and uniformly blanket the coated surface of a moving product of any width up to said given tunnel width and at any speed up to about 600 fpm.

The injector channel 18 must be located upstream from the inlet end 27 of entrance tunnel 16 a distance of at least about 10 times the smallest cross-sectional dimension of tunnel 16. The height (H) of the channel 18 should preferably be at least about four times greater than the width (W), i.e., the spacing between the side faces of the channel, as shown more clearly in FIG. 2. The length (L) of the channel must be at least substantially equal to thewidth of the product P and preferably equal to the width of the entrance tunnel 16 and must be oriented substantially parallel to the tunnel width. Moreover, the channel 18 must also be oriented such that the inert gas is directed through the channel opening 26 into the enclosure 10 at an included angle with respect to the longitudinal axis of the enclosure 10 of from between 4590, preferably The distance between opening 26 and the moving product P should be as small as normal product surface irregularities will allow. The height H to width W relationship is not as critical is a porous medium is used to fill the channel spacing, but this makes the assembly somewhat more difficult and moreexpensive to fabricate. Although the channel 18 is shown in FIG. 1 as a-pair of flat plates extending from a slot in the upper wall of tunnel 16, the slot itself may in fact represent the channel provided the upper wall of tunnel 16 is of sufficient. thickness to satisfy the desired height (H) to width (-W) relationship.

The gas supplied to the injector channel 18 flows Both the entrance tunnel 16 and the exit tunnel 2 4 are extensions of the radiation chamber 12 and serve to restrict the loss of inerting gas from the enclosure 10 as well as to direct the escaping inerting gas over the coated surface of the product P in such a manner as to push off most of the air from the surface of product P before the product enters the area of irradiation 14. A slight but significant pressure gradient exists between the injector channel opening 26 and the inlet end 27 of the entrance tunnel 16 which creates a back flow of inert gas out the entrance tunnel 16 so as to prevent an unacceptable quantity of air from being drawn in with the coated surface of product P. The exit tunnel 24 serves in addition, as an escape path for the minor amount of air which does enter the enclosure at the coated surface of product P and is carried downstream with the coated product P. The inerting gas holds such air at the coated surface of product P and sweeps such air out through the exit tunnel 24 along with the exiting product as opposed to letting such air intermix with the inert atmosphere in chamber 12 and accumulate to an unacceptable level.

The cross-sectional dimensions of the entrance and

exit tunnels

16 and 24 respectively are preferably selected to conform to the cross-sectional dimensionsof the coated product P to be treated. FIGS. 4(a-c) illustrates three typical tunnel geometries for three typical product shapes; viz., rectangular, triangular and cylindrical respectively. In addition, as shown in FIGS. 5a and 5b the injector channel 18 and plenum chamber 20 respectively, should likewise conform in geometry to the cross-sectional geometry of the coated product P. This is also true for the radiation chamber 12 where uniform irradiation is desired about the entire periphcry of the product but does notmean that the radiant energy source need have such geometry since by appropriate optics in the chamber 12 one can accomplish the same result.

As stated hereinbefore the tunnel length (T l to the injector channel for any tunnel configuration must be at least about ten times greater than the smallest crosssectional dimension of the tunnel. Hence, for a rectangular tunnel geometry T 2 (10) T and T T where T Tunnel height T Tunnel width; for a triangular tunnel geometry (FIG. 50) T 2 (10) T T and for a cylindrical tunnel geometry (FIG. 5b) T 200) D "war'eu'ime cross sect'ional 'dia' n i'eii of the cylinder. I

When the coated product P is present within the enclosure 10 and extends throughout the enclosure 10 the coated product itself may form the bottom of each tunnel. In such cases where the coated product P is continuously present, such as a web, the coated product P effectively forms the bottom of the chamber and no further bottom is required. In general, there should be no part of the irradiation area 14 physically lower than the bottom exposed surfaces of the entrance and exit tunnels l6 and 24 respectively. If it is necessary for some part of the irradiation area 14 to be lower than any of the lower surfaces of the tunnels then, in such instance, controlled leaks to the atmosphere should be provided along such physically lower surface. In such instance the nitrogen inerting gas will displace, downwardly, any air carried in with the product P forcing such air to exit from such leaks.

The enclosure 10 geometry has been discussed above in relation to the use of any inerting gas lighter than oxygen. It is to be understood that by a proper choice of controlled leak locations, a gas heavier than oxygen mental volumes V -V,',

could be used. Further, the chamber may also be physis cally reversed if desired.

The injector channel 18 assures an even flow distribution of inerting gas into the enclosure 10 with said flow directed substantially toward the. surface of the moving coated product P and uniformly distributed across the width of product P. The geometry of the injector channel 18 as discussed hereinabove is intended to cause each substantially equal elemental volume of inerting gas to see essentially parallel flow paths of equal length to the inlet opening of the entrance tunnel l6 and parallel flow paths of equal length to the outlet opening of the exit tunnel 24. This is diagrammatically shown in FIG. 6 with V V,, representing substantially equal discrete elemental volumes of inert gas flowing toward opening 27 and V Vn representing substantially equal discrete elemental volumes of inert gas flowing toward opening 29. Discrete elemental volumes V V,, need not be equal to discrete ele- Also, the flow path length from the opening 26 to the inlet end 27 of tunnel 16 need not be equal to the flow path length from the opening 26 to the'outlet end 29 of exit tunnel 24. .It is, however, significant to note that the inert gaseous flow emerging from the injector channel 18 cancels vectorially in all directions except in the longitudinal direction. This phenomenon is the primary factor in achieving uniform inert blanketing over the coated product width and in establishing the linearly scalable relationship between the inert gas flow and the tunnel width, in complete independence from the width of the coated product. Hence, as long as the tunnel openings are wide enough to accomodate the coated product P any narrower coated product width, no matter how narrow, may likewise be treated without altering the physical dimensions or flow rate. Moreover, the product speed may be varied at will up to about 600 fpm without affecting the treatment under the above noted conditions even though at the higher speeds the exposure time is substantially shortened.

FIG. 7 illustrates in perspective a typical apparatus operated according to the present invention as it might appear installed on a production line facility. A conveyor assembly 30 carries the coated product P to the treatment enclosure 10 which is supported by frame 34. Pressure actuated cylinders 32 control the height of the tunnels of the treatment enclosure 10 above the conveyor assembly 30. The cylinders 32 are manually controllable to adjust the enclosure tunnel height as well as being automatically responsive to a passing product having an irregular or warped surface which is not to be .treated. When such a product passes, the treatment enclosure 10 is automatically raised to a predetermined level while activating a shutter which passes beneath the radiation chamber 12. The shutter prevents the escape of radiant energy as will be explained more fully hereafter in connection with FIG. 8.

The radiation chamber 12 houses the electromagnetic radiation source and appropriate optics for directing the radiant energy toward the irradiating zone 14. It should be noted that in the typical system of FIG. 7 the conveyor surface is being partially used as the bottom surface of the treatment enclosure 10. Hence, the conveyor surfaces and the coated product P, when it extends through the treatment enclosure 10, forms an integral part of the enclosureacting as the bottom of the treatment chamber. This is more clearly seen in FIGS. 8 and 9.

The injector channel 18 is preferably formed as an elongated slot in the wall of the plenum chamber 20. it must however bear the proper geometrical relationship discussed heretofore, i.e., it must be spacially oriented so as to direct the inert gas at the moving product at an included angle with the longitudinal axis of the enclosure of from between 45-90.

The channel 18 should, in addition, have a height to width relationship of at' least about four to one. in the actual fabricated prototype the height (H) is formed from k inch thick plate with a channel spacing of H16 inch (W). Between the

conveyor sections

38 and 40 and resting upon frame 34 isa platform assembly 42 which in conjunction with the conveyor surfaces form the bottom surface of the treatment enclosure 10. Platform assembly 42 is comprised of a first sheet of Teflon with a number of mirror sections 44 which are directly exposed to the radiation chamber 12 and a second support sheet lying beneath thefirst sheet. The mirror sections 44 of the platform assembly 42 reflect some of the electromagnetic energy to the edges and underside of the passing product.

As stated before in connection with FIG. 7, when a product is presented which is not to be treated because of its irregular surface or otherwise, the pressure actuated cylinders 32 are automatically activated by means not shown thereby lifting the treatment enclosure to a predetermined height above the

conveyor assemblies

38 and 40 and platform assembly 42. Operating at such time in conjunction with the pressure actuated cylinders 32 is a further pressure actuated cylinder 36. Cylinder 36 has a piston rod 46 connected at its free end to a bracket 48 which is slidably mounted, through means such as ball bearings, on .a fixed shaft 52. The bracket 48 is also connected to a shutter assembly 50 also mounted for axial movement on fixed shaft 52. The bottom plate of the shutter assembly 50 represents the upper surface of exit tunnel 24. When the pressure actuated cylinder 36 is activated the piston rod 46 recedes causing the shutter assembly 50 to extend beneath and enclose the radiation chamber 12. A cooling medium is passed through conduits 54 to cool the shut ter assembly 50.

FIG. 9 is a sectional view taken along the lines 99 of FIG. 8. The tunnel passageway leading into the irradiation zone 14 is clearly illustrated with its top surface represented by the plenum chamber surface 56 and its bottom surface represented by the platform assembly 42. When the treatment enclosure 10 is lowered into its operating position the spacer plates 58 located on opposite sides thereof abut against the platform assembly 42 forming a pair of side walls for the entire treatment enclosure 10. A pair of side flaps (not shown) may also be used if controlled operating variation in tunnel height is desired above the first fixed-level determined by spacer plates 58.

In the apparatus shown in FIGS. 7-9 the internal enclosure width is approximately 50 inches, i.e., a product of any width up to a maximum of about 48 inches is acceptable for treatment. The height of the tunnels l6 and 24 respectively, in the enclosure operating position, is 3/8 inch. The-length of the enclosure 10, end to end, is 60 inches. The distance from the inlet end of inlet tunnel 16 to the injector channel is approximately 18 inches while the distance from the injector channel 18 to the radiation chamber 12 is approximately 6 inches. The radiation chamber 12 has a length of approximately 18 inches. The physical dimensions herein given are illustrative only and may be scaled up or down to suit a particular production facility. It should be kept in mind that since the gas flow requirement is predictable, in keeping with the gas flow tunnel width relationship given heretofore, the physical dimensions can thus be selected in accordance with available space on the production facility.

When the above described apparatus is in operation, the inert gas flow preferably nitrogen may be determined in accordance with the relationship betweenflow and tunnel width as set forth earlier, namely, about 400 cfh/ft. of tunnel width. Alternatively, a total flow corresponding to a, normal product width and hence maximum tunnel width, for a particular commercial user, may be set without the necessity of further adjustment for product width variations.

The following is set of examples where the total gas flow rate was fixedly set at about 1500 cfh for products of widely varying widths up to a maximum of about 48 inches and'widely varying speeds from fpm to 500 fpm. The thickness of the product varied up to A inch.

A coating composition was prepared from 50g acrylated epoxidized soybean oil, 30g hydroxyethyl acrylate, and 20g neopentylglycol diacrylatefTo 10g aliquots of this composition was added 0.01 mole of various sensitizers. The coating was applied at a wet film thickness of2 mils to Bonderite No. 37 steel panels and irradiated at the indicated explosures, under nitrogen blanketing, using a Plasma Arc Radiation Source. Results of analysis of the cured films are listed below:

trate and lift film from metal substrate I claim:

1. Apparatus for in-line irradiation treatment of a moving product comprising:

a. a first and second tunnel of substantially uniform cross section each having an inlet end and an outlet end;

b. a treating chamber having at least one treating source mounted therein, said chamber being located intermediate the outlet end of said first tunnel and the inlet end of second tunnel and forming therewith a a continuous enclosure;

0. means for maintaining a substantially inert atmosphere at the surface of said moving product comr s n s A 1. an elongated gas'injctor c'hannl haviiig a first open end communicating with said enclosure and located intermediate said first tunnel opening arid said treatment chaifibefirid fufiher located from the inlet and of said first tunnel a' distance equal to at least about ten times the smallest cross-sectional dimension of said first tunnel.

' said first open end having a length at least substantially equal to the Width of said product with the longer axis of said opening directed substantially parallel to the width of said first tunnel;

2 a plenum chamber connected to a second open end of said channel; and

3 a source of inert gas for continuously introducing inert gas into said plenum chamber.

2. Apparatus as defined in claim 1 wherein said gas injector channel is spacially oriented to direct said inert gas toward said product at an included angle of from between 45 90 with respect to the longitudinal axis of said enclosure.

3. Apparatus as defined in claim 2 wherein said gas injector channel is the sole means for introducing inert gas into said enclosure.

- 4. Apparatus as defined in claim 3 wherein the first open end of said channel is disposed in relatively close proximity to said moving product.

5. Apparatus as defined in claim 1 wherein said gas injector channel is a slotted groove formed in the upper wall of said first tunnel and has parallel side faces.

6. Apparatus as defined in claim 5 wherein said injector channel has a height at least four timesgrea'ter than the channel width.

7. Apparatus as defined in claim 6 wherein said first and second tunnels have a cross-sectional geometry substantially conforming to the cross-sectional geometry of said product.

8. Apparatus as defined in claim 7 wherein the smallest cross-sectional area of said plenum chamber is at least about ten times greater than the longitudinal cross-sectional area of said channel.

9. Apparatus as defined in claim 8 wherein said inert gas is nitrogen.

11. Apparatus as defined in claim 10 wherein said enclosure has a bottom planar surface upon which the product passes representing the bottom side of said first tunnel, said treating chamber and said second tunnel respectively.

12. Apparatus as defined in claim 10 wherein said product is a continuous web which once extended through said enclosure forms the bottom surface thereof.

13. Apparatus as defined in claim 11 wherein said bottom surface includes at least one relatively small aperature communicating with the atmosphere. V r

14. Apparatus as defined in claim 13 further comprising means for raising said enclosure a predetermined distance above said product in response to a product which is not to be treated and means operating in con junction therewith for passing a shutter beneath said treatment chambe'rto prevent the escape of radiant energy.

15. Apparatus as defined in claim 14 wherein said enclosure further comprises. means for controllably adjusting the height of said tunnels.

16. Apparatus as defined in claim 1 wherein said treating source is an internally cooled plasma arc source.

17. Apparatus as defined in claim 1 wherein said treating source consists of at least one non-cooled low pressure shortwave ultraviolet mercury tube or germicidal tube.

UNITED STATES PATENT OFFiCE CERTIFICATE OF CORRECTION Patent No. 3,807, 052 Dated April 30-, 197 4 Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent hereby eerrectecl as shown below:

In Claim 5, line 1, the numeral 1 should read 4.

Signed and sealed this 15th day of October 1974.

(SEAL) Attest:

McCOY M; GIBSON JR. 0. MARSHALL DANN Commissioner of Patents Attesting Officer

Claims

1. Apparatus for in-line irradiation treatment of a moving product comprising: a. a first and second tunnel of substantially uniform cross section each having an inlet end and an outlet end; b. a treating chamber having at least one treating source mounted therein, said chamber being located intermediate the outlet end of said first tunnel and the inlet end of second tunnel and forming therewith a a continuous enclosure; c. means for maintaining a substantially inert atmosphere at the surface of said moving product comprising 1 an elongated gas injector channel having a first open end communicating with said enclosure and located intermediate said first tunnel opening and said treatment chamber and located from the inlet end of said first tunnel a distance equal to at least about ten times the smallest cross-sectional dimension of said first tunnel, said first open end having a length at least substantially equal to the width of said product with the longer axis of said opening directed substantially parallel to the width of said first tunnel; 2 a plenum chamber connected to a second open end of said channel; and 3 a source of inert gas for continuously introducing inert gas into said plenum chamber.

2. Apparatus as defined in claim 1 wherein said gas injector channel is spacially oriented to direct said inert gas toward said product at an included angle of from between 45* - 90* with respect to the longitudinal axis of said enclosure.

4. Apparatus as defined in claim 3 wherein the first open end of said channel is disposed in relatively close proximity to said moving product.

6. Apparatus as defined in claim 5 wherein said injector channel has a height at least four times greater than the channel width.

9. Apparatus as defined in claim 8 wherein said inert gas is nitrogen.

10. Apparatus as defined in claim 9 wherein the cross-sectional geometry of said channel substantially conforms to the cross-sectional geometry of each of said first and second tunnels.

13. Apparatus as defined in claim 11 wherein said bottom surface includes at least one relatively small aperature communicating with the atmosphere.

14. Apparatus as defined in claim 13 further comprising means for raising said enclosure a prEdetermined distance above said product in response to a product which is not to be treated and means operating in conjunction therewith for passing a shutter beneath said treatment chamber to prevent the escape of radiant energy.

15. Apparatus as defined in claim 14 wherein said enclosure further comprises means for controllably adjusting the height of said tunnels.