NZ206929A - Labelling envelopes by continuous adhesive label transfer - Google Patents

Description

^929 No.: Date: Priority Oate(s): ...

Complete Specification Filed: class: &6?£LlQ3)..86SC9J3Ct.

Publication Dato: ... P.! P.O. Journal, No: NEW ZEALAND PATENTS ACT. 1953 . V A ^ - " 'Cvv - J>1 V/>w ■> O COMPLETE SPECIFICATION 'RECIPROCAL LABELING OF PACKAGING ENVELOPES" £yWe W. R. GRACE $ CO., a corporation organized and existing under the laws of the State of Connecticut, United States of America, of 1114 Avenue of the Americas, New York, N.Y. 10036, United States of America, hereby declare the invention for which/ we pray that a patent may be granted to tnsx/us, and the method by which it is to be performed, to be particularly described in and by the following statement:- 206920 BACKGROUND OF THE INVENTION This invention relates generally to improved method and apparatus for applying printed labels to flexible packaging envelopes and more particularly to such labeling carried out reciprocally so that both sides of such envelopes are labeled in registration.

It is typical for thermoplastic packaging bags to bear printed labels of advertising material or content description. Bags may be labeled after manufacture, or, alternatively, bags may be formed from a stock of thermoplastic film material which has already been labeled before conversion into the packaging envelope. It is known to bond a thermoplastic film bearing labeling indicia to a thermoplastic packaging bag by corona discharge treating the film faces to be bonded and then contacting those faces afterwhich they adhere together permanently. Other energetic adherent surface treatments are known.

In making thermoplastic packaging bags, it is conventional to make a series of such bags from a flattened Seamless tubular film of indefinite length. A series of end-seal bags may be made by transversely » . • heat sealing across the width of the flattened tubing, followed by severing the tubing so that the transverse seal forms the bottom of a bag. A series of side-seal bags may be made similarly except that the transverse seals form the bag sides and one edge of the collapsed tubing forms the bottom of the bags.

Of general interest is the disclosure of New Zealand Patent^ Specification No. 184124 , j " " " " ■, wherein a labeling method is disclosed that includes bonding a labeling film to a collapsed tubular film by corona treating the faces of the respective films to be brought into contact and then contacting the treated film faces without a 6 ; application of heat to bond the labeling film to the tubular substrate.

It is a primary object of the present invention to provide for reciprocal labeling of an advancing collapsed tubular film preliminary to bag making whereby reciprocal labels are bonded to opposite sides of the collapsed film at regular intervals such that the labels of each reciprocal set are in registration respectively.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a method for reciprocal labeling of packaging envelopes comprising (a) advancing a collapsed tubular polymeric film of indefinite length and adherently treating the outer surface of the collapsed film, (b) advancing a printed web of indefinite length, having printed along one surface thereof a regularly repetitive pattern of reverse-printed reciprocal label sets, and adherently treating the printed surface of the web, (c) longitudinally slitting the advancing web between reciprocal prints to form two reciprocal label strips, and (d) advancing the label strips oppositely alongside the advancing collapsed film such that the adherently treated surfaces of the strips are adjacent opposing sides of the collapsed film respectively and adjusting the registration of printed matter between said label strips, and (e) then directing the strips into bonding contact with the collapsed film.

The terra "adherently treating" is intended to refer to energetic treatment of a surface, especially a polymeric surface, to impart adhesive properties thereto, such as by corona discharge, flame, ultra violet, or plasma treatment. Preferably, such treatment is by corona discharge.

Since the reciprocal label strips are formed from a single printed web, control of registration of reciprocal label sets in the final bonded configuration is greatly facilitated, with no control being necessary after initial registration set-up in most cases.

Additionally, there is provided apparatus for reciprocal labeling of packaging envelopes comprising (a) means for adherently treating the outer surface of an advancing collapsed tubular film, (b) means for adherently treating the printed surface of an advancing reverse-printed web, having printed along one surface thereof a regularly repetitive pattern of reverse-printed reciprocal label sets, (c) means for longitudinally slitting the advancing web between reciprocal prints to form two reciprocal label strips, (d) means for advancing the label strips oppositely alongside the advancing collapsed film such that the adherently treated surfaces of the strips are adjacent opposing sides of the collapsed film respectively and adjusting the registration of printed matter between said label strips, and (e) means for directing the strips into bonding contact with the collapsed film.

BRIEF DESCRIPTION OF THE DRAWINGS 1 ■ ■■' ■■ 11 t 11 Further details are given below with reference to the drawings wherein: FIG. 1 is a schematic side-view of a process line for reciprocal labeling of a collapsed tubular film according to an embodiment of the invention; and FIG. 2 is a schematic side-view of an auxiliary process line feeding labeling material to the main process line of the previous figure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring specifically to the drawings, in FIG. 1 a schematic side-view of the main process line according to a preferred embodiment of the invention is shown wherein a collapsed tubular film of indefinite h length is reciprocally labeled preliminary to converting the tube into a series of packaging bags. A conventional extrusion unit 12 extrudes an inflated tube 14 of thermoplastic packaging film which is then collapsed to a lay-flat configuration by a pair of pinch rollers 16, the collapsed tubular film being indicated at 18. A representative packaging film is composed of polyethylene. Alternatively, the tubular film maybe supplied in roll form which when fed out from the roll is preferably inflated as at 14 to break any cling of the interior surfaces of the tube as may result from compression in roll form. The collapsed tubular film 18 is then advanced in-line to a corona treatment unit 20 wherein one side of the collapsed tubular film is corona treated between conventional corona unit 22a and discharge roller 23a followed by treatment of the opposing side of the collapsed tubular film between corona unit 22b and discharge roller 23b. The collapsed tubular film exits the corona treatment unit 20 at 24 having had substantially its entire outer surface treated by corona discharge. The treated collapsed film 24 is then advanced in-line between reciprocal label strips 26a,b and then to bonding roller 34 where I • the tubular film is reciprocally labeled, i.e. the collapsed film is oppositely labeled on its exterior lay-flat sufaces such that labels of each reciprocal label set are substantially in registration. The plane of the main process line 10 is indicated by line 1-1.

Labeling material is fed to the main process line 10 from auxiliary process line 50 as discussed below in connection with FIG. 2, the auxiliary line being aligned in plane 2-2 generally perpendicular to plane 1-1. Upper label strip 26a is fed to the main process line 10 over a conventional 45° turn bar 28a as indicated at location 27a and exits under turn bar 28a so that upper label strip 26a travels parallel and adjacent to collapsed tubular film 24 and is then directed over roller r D 32a and then to bonding roller 34. As discussed below, upper label strip 26a has reverse-printed labeling matter on its lower surface, this same surface having been corona treated for bonding to collapsed film 24. Collapsed film 24 is reciprocally labeled on its underside with label strip 26b which is fed from auxiliary process line 50 over a 45° turn bar 28b as indicated at location 27b to exit under turn bar 28b and is then passed over reversing rollers 30 and 31 so that lower label strip 26b is traveling with and adjacent to collapsed tubular film 24. As discussed below, lower label strip 26b has reverse-printed labeling matter on its upper surface, this same surface having been corona treated. The lower label strip 26b is next passed over roller 32b and onto bonding roller 34 so that at bonding roller 34, by virtue of tension roller 40, upper label strip 26a and lower label strip 26b are urged against opposite surfaces of collapsed tubular film 24, whereupon the label strips are permanently bonded to the collapsed film at 36. The bonded configuration at 36 is then directed from bonding roller 34 around tension roller 40 whereupon the reciprocally labeled tubular film at 42 exits the main process line and is either directly advanced to a bag making operation as discussed above or is accumulated in roll form for later bag making. It is noted that the printed labels in the final bonded configuration will lie between the label strips and the tubular film, respectively, to provide abrasion protection for the labels thereby preserving labeling appeal and also to impart an attractive glossy appearance. Since the labeling material will be read in reverse in this configuration, the labels must be initially reverse-printed.

In FIG. 2, there is schematically shown auxiliary process line 50 which feeds main process line 10, auxiliary line 50 lying in plane 2-2 which is preferably perpendicular to the main process line 10 lying in plane 1-1. Auxiliary line 50 begins with the provision of a roll of 6 printed web 51, having printed along one surface thereof a regularly repetitive pattern of reverse-printed reciprocal label sets, from which label strips 26a,b are prepared. The term "reciprocal label set" is intended to imply that front and back labels of each label set are simultaneously printed side-by-side on the web 51. This reciprocal printing arrangement is advantageous in that registration between front and back labels in the final bonded configuration is easily achieved, due to the regularity of repeat spacing between front labels and back labels respectively, and further in that any need for a two-side printing press is eliminated. The web is composed of a thermoplastic material compatible with the thermoplastic material of the collapsed tubular film. The supply of printed web is fed out at 52 and advanced in-line to corona treatment unit 54 where the printed side of the web is subjected to corona discharge treatment between conventional corona unit 55 and discharge roller 56. The corona treated web is then advanced to slitter 58 which cuts the web longitudinally along a line lying between front and back labels of each reciprocal label set, such that at location 60 two reciprocal label strips will be advancing side-by-side and upon being passed over roller 62 are separated into upper label strip 26a and lower label strip 26b. Lower label strip 26b is then directed onto turn bar 28b at 64 where it is passed around the bar in the direction of arrow 29b and exits under the bar as indicated at 65 (flowing into the plane of the drawing). Since label strip 26b at this point will be advancing opposite that of collapsed tubular film 24, it is then reversed over rollers 30 and 31, as discussed above, such that strip 26b exits over reversing roller 31 as indicated at 66 having been rotated in the direction indicated by arrow 33.

Referring to the point of separation of upper and lower label strips at roller 62, upper label strip 26a is passed through a longitu 1 dinal registration control unit 70 haviag reversing rollers 71 and 74 and tension rollers 72 and 73. Tension rollers 72 and 73 operate in unison by reciprocal displacement about center of rotation 75 so that as tension rollers 72 and 73 are displaced the inventory of upper label strip 26a is varied within controller 70. In general, longitudinal registration control is accomplished by selectively adjusting the path length of one of the label strips. Upper label strip 26a exits from registration controller 70 over turn bar 28a as indicated generally at 68 and rotates about 45° turn bar 28a in the direction indicated by arrow 29a to exit under the bar as indicated at 69. Upon upper label strip 26a exiting under turn bar 28a at 69 and upon lower labeling strip 26b exiting over reverse roller 31 at 66, upper and lower strips 26a,b will be travelling adjacent to and with collapsed tubular film 24 such that the corona treated surfaces of labeling strips 26a,b are towards collapsed film 24 respectively. It is noted that the label strips are routed so as not to abrade their corona treated surfaces or the printed matter thereon, this being possible since both features are on the same surfaces, respectively. Additionally, it is preferred that sliding friction over the turn bars be minimized, so as not to irregularly stretch the label strips, by air-lubricating the turn bars or by providing a low friction coating such as Teflon. Transverse registration of printed matter between the label strips is simply adjusted by varying the longitudinal spacing between the turn bars 28a,b, i.e. by shifting one or both of the turn bars along the longitudinal direction of tubular film 24 the transverse location of the respective label strips will be shifted across the tubular film.

A key advantage of the invention is that in most cases continuous registration control is not required after initial longitudinal <2 and transverse registration adjustment as described above. This advantage arises from the requirement that front and back label strips are formed from a single web on which are printed reciprocal label sets so that front and back labels are always juxtaposed and have the same repeat distance. However, in cases where there is a defect in the regularity of the web, such as a deficiency in planarity, continuous monitoring of registration with feedback control may optionally be provided if the irregular web is to be used. For example and referring to FIG. 1, in the vicinity of location 36 where label strips 26a ,b have been bonded to tubular film 24 on bonding roller 34, the registration of upper and lower reciprocal labeling is continuously monitored. A preferred location for registration monitoring is just down-course from rollers 32a,b. Alternatively though less preferred, monitoring may be conducted after bonding just down-course from 36. In response to this registration monitoring, longitudinal registration control unit 70 is automatically adjusted accordingly, and likewise for transverse registration via turn bar spacing, to maintain registration of reciprocal labeling within acceptable limits. Monitoring can be conducted by conventional means, for example by a photoelectric detector cell pair to optically sense two dimensional registration of each reciprocal label set.

Regarding bag making from the reciprocally labeled collapsed tubular film, proper orientation of printed matter on the label strips must be predetermined. If side-sealed bags are made such that the folded edges of the collapsed tubing form the top and bottom of a bag, then the label strips will extend across the bag, and printed matter on the label strips will usually be oriented transversely on the strip. On the other hand, if end-seal bags are made from the collapsed tubing, the label strips will extend lengthwise of the bag, and printed matter on the label strips will usually be oriented lengthwise on the strips. It is noted that the label strips will typically be of a width less than the width of the collapsed tubing. Transverse location of the label strips on the tubing is as desired and, for example, will be placed towards the edge of the tubing that will form the bag bottom in the case of side-seal bags.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be utilized without departing from the principles and scope of the invention, as those skilled in the art will readily understand. Accordingly, such modifications and variations may be practiced within the scope of the following claims:

Claims (15)

WHAT }flWE CLAIM IS: WHAT IS CLAIMED IS:

1. A method for reciprocal labeling of packaging envelopes, comprising: a) advancing a collapsed tubular polymeric film of indefinite length and adherently treating the outer surface of said film; b) advancing a printed web of indefinite length, having printed along one surface thereof a regularly repetitive pattern of reverse-printed reciprocal label sets, and adherently treating the printed surface of said web; c) longitudinally slitting said advancing web between reciprocal prints to form two reciprocal label strips; and d) advancing said label strips oppositely alongside said advancing collapsed film such that the adherently treated surfaces of said strips are adjacent opposing sides of said collapsed film respectively and adjusting the registration of printed matter between said label strips; and e) directing said strips into bonding contact with said collapsed film.

2. The method of claim 1 wherein said label strips are advanced alongside said collapsed film by turning one of said strips over a turn bar in the direction of said advancing collapsed film, while turning the other of said strips over a turn bar in the opposite direction and then over a reversing roller.

3. The method of claim 1 wherein said registration adjusting further comprises selectively varying the in-line inventory of one of said label strips for longitudinal registration of printed matter between said label strips.

4. The method of claim 2 wherein said registration adjusting further comprises selectively varying the longitudinal spacing between said turn bars for transverse registration of printed matter between said label strips.

5. The method of claim 1 further comprising continually monitoring the registration of printed matter between said label strips and in response thereto controlling said registration at a location prior to said bonding contact.

6. The method of claim 1 further comprising transversely sealing said collapsed film at regular intervals to form a series of envelopes.

7. Apparatus for reciprocal labeling of packaging flexible envelopes, comprising: a) means for adherently treating the outer surface of an advancing collapsed tubular film; b) means for adherently treating the printed surface of an advancing printed web, having printed along one surface thereof a regularly repetitive pattern of reverse-printed reciprocal label sets; c) means for longitudinally slitting said advancing web between reciprocal prints to form two reciprocal label strips; d) means for advancing said label strips oppositely alongside said advancing collapsed film such that the adherently treated surfaces of said strips are adjacent opposing sides of said collapsed film respectively, and means for adjusting the registration of printed matter between said label strips; and e) means for directing said strips into bonding contact with said collapsed film. a

8. The apparatus of claim 7 wherein said advancing means further comprise means for turning one of said strips over a turn bar in the direction of said advancing collapsed film, while turning the other of said strips over a turn bar in the opposite direction and then over a reversing roller.

9. The apparatus of claim 7 wherein said means for registration adjusting further comprise means for selectively varying the in-line inventory of one of said label strips for longitudinal registration of printed matter between said label strips.

10. The apparatus of claim 8 wherein said means for registration adjusting further comprise selectively varying the longitudinal spacing between said turn bars for transverse registration of printed matter between said label strips.

11. The apparatus of claim 7 wherein said means for registration adjusting further comprise means for continually monitoring the registration of printed matter between said label strips and in response thereto controlling said registration at a location prior to said bonding contact.

12. The apparatus of claim 7 further comprising means for transversely sealing said collapsed film at regular intervals to form a series of envelopes.

13. A method as claimed in any one of claims 1 to 6 when / performed substantially as hereinbefore described with reference to any of the accompanying drawings. 13 - 14 -

14. Apparatus as claimed in any one of claims 7 to 12 substantially as hereinbefore described with refei'ence to any of the accompanying drawings.

15. A method as claimed in any one of claims 1 to 6 and 13 when performed using an apparatus as claimed in any one of claims 7 to 12 and 14. DATED THISDAY OF ' X L C A. J. PARK & SON PEfl AGENTS FOR THE APPLICANTS