US3030915A - Apparatus for making heat sealable wrapper - Google Patents

Description

April 24, 1962 A. v. SHANNON 3,030,915

APPARATUS FOR MAKING HEAT SEALABLE WRAPPER Filed April 30, 1957 3 Sheets-Sheet 1 INVENTOR.

ARTHUR VERNON SHANNON ATTURNEE April 24, 1962 A. v. SHANNON APPARATUS FOR MAKING HEAT SEALABLE WRAPPER Filed April 50, 1957 3 Sheets-Sheet 2 {HOT MELT I RESERVOIR I L RUBBER PATTERN ROLL r l l l l I l l l l I I I INVENTOR.

ARTHUR VERNON SHANNON April 24, 1962 A. v. SHANNON APPARATUS FOR MAKING HEAT SEALABLE WRAPPER Filed April 30, 1957 3 Sheets-Sheet 3 INVENTOR.

ARTHUR VERNON SHANNON ATTORNEYS.

United States atent 3,030,915 APPARATUS FOR MAKING HEAT SEALABLE WRAPPER 7 Arthur Vernon Shannon, Princeton, N.J., assignor to Pacon Research & Development Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 30, 1957, Ser. No. 656,069 2 Claims. (Cl. 118-202) The invention relates to a method and apparatus for making a heat scalable wrapper or liner strip of metal foil or other suitable material for delivery to a wrapping machine in continuous lengths as the strip is being prepared.

Metal foil, and especially aluminum foil, is widely used as an outer wrapping for food products and other goods packaged in paperboard cartons. Generally the foil is paper-backed and its metal face is printed or lithographed to describe and advertise the contents of the package. Among the reasons for use of paper-backed aluminum foil is that it is quite impervious to moisture and is therefore a help in keeping products fresh and marketable. Where this is to be considered, it is also regarded essential to provide an effective seal at the edges of the wrapper. One way of sealing the Wrapper has been to provide a layer of wax over the paper side of the foil composite with an added layer of paper over the wax, and to apply heat to the outside of the wrapper wherever a seal is wanted. The heat melts the wax which bleeds through the layer of paper and then solidifies to form an adhesive film between overlapping edge portions of the wrapper. While this method has been used very widely, it has a number of disadvantages. Frequently the wax bleeds through where a seal is not wanted, as between the wrapper and the paperboard carton, creating an adhesive bond which may be objectionable. Because the added layer of wax and paper extend over the entire area of the wrapper, the sealing means is not confined to the areas to be sealed. This is quite uneconomical and adds to the cost of the package. Besides, there is no way of getting a seal in the places where the outer face of the wrapper is folded over against itself as occurs in the diagonal folds at the corners of the wrapper and Wherever one folded section is brought against another. In such places the wax cannot bleed through to provide a seal. Yet they are the very places where a seal can be most important; and the unsealed edges can catch and tear so that the package becomes unsightly and may even come unsealed. It is an object of my invention to overcome these and other disadvantages of the wrappers and wrapping methods generally used heretofore.

Kbcording to my invention, a melted thermoplastic adhesive material is applied in a special manner to predetermined sealing areas of the face of the wrapper (or liner) strip of metal foil or other suitable material as it is being prepared for delivery to a wrapping machine. Many problems were encountered before it was discovered how to apply hot melted adhesive to the wrapper in a pattern designed for the sealing areas, and in registry with the printed or lithographed face of the wrapper. In the end, I found that highly satisfactory results could be obtained by cutting, in a heat resistant rubber surface such as the surface of a silicone rubber covered roll, a pattern in relief for the sealing areas of the wrapper strip, heating the pattern surface, applying melted adhesive material to the pattern, bringing the outer face of the wrapper strip into rolling contact with the melted adhesive material applied to the pattern, and withdrawing the strip from such rolling contact to produce, upon setting up of the melted adhesive material, a wrapper strip having, upon its outer face, predetermined sealing areas coated with the hot melt adhesive material. By correlating this procedure with the operation of conventional packaging machinery it was found possible to use quite a thick layer of the hot melt adhesive-as could not be done without the greatest diiiiculty if the adhesive-patterned strip were wound into rolls before delivery to the packaging plant, because the disparity in thickness created by the pattern of relatively thick hot melt adhesive would give a spongy, uneven, roll. With the use of my invention, the thickness of the plastic layer may, for example, be as great as 2 mils or more. The wrapper strip is brought into contact with the heated silicone rubber pattern roll with the printed face of the wrapper in registry with the pattern. The melted adhesive is applied to the pattern by means including an applicator roll turning in a heated reservoir containing the melted adhesive material. The reservoir includes cylindrical walls closely surrounding the surface of the applicator roll, and galleries over which the melted adhesive flows to the ends of the applicator roll for lubrication of the roller bearings, re-distribution to the surface of the applicator roll and to maintain uniformity in temperature throughout the heated reservoir.

Other features and advantages of the invention will appear as the description proceeds. In the drawings, wherein I have illustrated the best mode contemplated by me for carrying out my invention:

FIG. 1 is a face view of the outside of a heat scalable wrapper strip made in accordance with my invention.

FIG. 2 is a perspective view of a package showing how a wrapper cut from the strip of FIG. 1 is applied as an outer sealed wrapping. In this View the final flap folding and sealing operation remains to be performed.

FIG. 3 is a diagrammatic view of my apparatus for making the heat scalable wrapper strip for delivery to a wrapping machine in continuous lengths as the wrapper strip is being prepared.

FIG. 4 is a perspective view of the hot melt applicator roll and rubber pattern roll of the F IG. 3 apparatus, drawn to a larger scale.

FIG. 5 is a detail view taken as indicated at 5-5 in FIG. 4, and showing the grooved surface of the hot melt applicator roll.

FIG. 6 is a vertical sectional view through the center of the hot melt reservoir and applicator and pattern rolls of the FIG. 3 apparatus.

FIG. 7 is a top view of the hot melt reservoir taken as indicated at 7-7 in FIG. 6, and with the hot melt applicator roll removed to show clearly the flow passages for the hot melt adhesive material.

FIG. 8 is a detail cross sectional view taken as indi cated at 8-45 in FIG. 7, drawn to an enlarged scale.

In FIG. 1, which represents a continuous length of my heat scalable wrapper stripper 9, the section which lies between successive cut lines as represented by the dot dash lines 10 and 11, comprises one complete wrapper. As a preferred example of the practice of my invention, it may be considered that the wrapper strip 9 is a paperbacked aluminum foil. In FIGS. 1 and 2 we see the outer metal face of this strip. The strip will ordinarily be delivered to my apparatus as a continuous printed web 12 (FIG. 3). For example, the printing wil-l usuaily appear within the several areas which are exposed on the six sides of the sealed wrapper. The several areas available for printing are designated at 13, the approximate boundaries of which have been indicated by full lines. Other areas which become sealed, or partially so, are indicated by dot dash lines, and Within them the outer face of the wrapper strip has predetermined sealing areas coated with hot melt adhesive material as indicated by the several stippled areas 14. These predetermined sealing areas are applied in registry with the printing. Notice in FIG. 2 that upon completion of the folding and sealing of the end flaps 15, 16, 17 and 18, the sealed areas will extend to the outer edge 19 and diagonal fold edges 20 of the outer end flap 18. With the widely used sealing method described at the beginning of the specification, a seal would not be obtained between the metal to metal contacts at the corners, so that the sealing areas do not extend all the way to the edges 20. With the use of my wrapper the seal can be made to extend to the edges of the flaps and the diagonal fold edges throughout, so the same condition would be obtainable at the edges 21, 22 and 23. If desired, however, it is possible to leave one edge unsealed sufiiciently to permit easy opening of the package.

Referring to FIG. 3, I will now describe the general arrangement of the apparatus which is particularly designed as a unit which can be mounted upon a conventional wrapping and sealing machine, taking the printed web 12 as delivered from a roll (not shown) and delivering the heat scalable wrapper strip 9 to the wrapping mechanism at the point which may be generally indicated at 24. In its general arrangement the apparatus for making the heat scalable wrapper strip for delivery to the wrapping machine in continuous lengths as the wrapper strip is being prepared, comprises a heat resistant rubber surface such as the surface of a silicone rubber covered roll (designated Rubber Pattern Roll), a pattern 25, in relief, for the sealing areas of the wrapper strip cut in said surface, means for heating the pattern surface such as an electrical resistance heater 26, means for applying melted adhesive material to the pattern including a hot melt applicator roll and a hot melt reservoir, means for bringing the outer face of the wrapper strip into rolling contact with the melted adhesive material applied to the pattern, including an idler or drive nip roller 27 and drive roller 28, and means for withdrawing the strip 9 from such rolling contact including an infinitely variable speed reducer and control 29, differential drive and control 30, dancer mechanism 31, and auxiliary drive roller 32. An electric eye 33 with associated control mechanism 34 is provided in conjunction with the differential drive control 30 for maintaining registry between the printed areas of the web 12 and sealing areas coated with hot melt plastic material.

The printed web 12 passes around the drive nip roller 27 in a clockwise direction, thence around dr-ive roller 28, counterclockwise, into contact with the melted adhesive material applied to the pattern 25 of the rubber pattern roll 6t), and the wrapper strip 9 with its predetermined sealing areas coated with the hot melt adhesive material is then drawn around the auxiliary drive roll 32, over idler roller 35, dancer roller 36 and idler roller 37.

The apparatus may be driven from any suitable power source such as the electric motor '38 which puts the power into the infinitely variable speed reducer mechanism 29. This mechanism may be of any well-known construction designed for operation from zero speed up to the desired maximum. The speed is controlled through a control arm or other device 39, indicated diagrammatically by a broken line, in response to the position of dancer roller 36 carried by hearing blocks 40 slidable up and down in a guideway 41 of frame 42. A weight W suspended from bearing block 40 applies a predetermined tension to the wrapper strip 9. The function of the dancer roller mechanism is to maintain constant tension in the wrapper strip as it is delivered to the wrapping machine, and to correlate the speed of the hot melt applicator mechanism 61 with the speed of operation of the wrapping machine. As the speed of operation of the wrapping machine increases, it becomes necessary to increase the speed of the hot melt applicator mechanism. The first effect of the increase in speed of the wrapping machine is to draw the wrapper strip 9 more rapidly through the dancer mechanism which will elevate the dancer roller 36 from the position shown in full lines in FIG. 3, changing the position of control 39 to increase the speed of the output shaft 43 of the speed reducer 29, speeding up the operation of the hot melt applicator mechanism. An extreme position of dancer roller 36 is indicated by the dot dash line at 36. In practice the movement of the dancer roller may be very slight, and it generally will move to some particular position and remain there with almost imperceptible changes in position. The effect, as stated, is to maintain the tension in the wrapper strip 9 within negligible limits of variation, while at the same time correlating speeds of the wrapping and applicator mechanisms. Output shaft 43 is suitably connected in driving relation to the input shaft 45 of the differential drive mechanism 30 as by means of chain 44 and sprockets fixed to the respective shafts.

The hot melt applicator roll 61 is driven from shaft 45 by means of the chain 46. The rubber pattern roll is driven from the hot melt applicator roll as by means of gears 47 and 48 fixed to the respective shafts. The gear ratio is such that the pitch diameters of gears 47 and 48 are in direct relation to the diameters of the surfaces of the hot melt applicator and pattern rolls. This gear ratio may be varied to suit different sizes of pattern rolls as may be needed to accommodate wrappers of different lengths. Drive roller 28 is driven from the output shaft 49 of differential drive 30 as by means of a chain 50 and sprockets fixed to the output shaft 49 and the shaft 51 of drive roller 28 respectively. The function of the differential drive 39 is to correlate the speeds of the rubber pattern roll and drive roller 23 so as to maintain registry between the printed surface of web 12 and the predetermined sealing areas coated with the hot melt material. In the operation of the apparatus minor variations can occur which would bring the areas out of proper registry, but this is prevented from happening by the operation of differential drive 30 and its electrical control mechanism 34. The electric eye 33 of the control mechanism sees an index mark 52 (FIG. 1) which may be applied to the web 12 as a part of the printed pattern. In some cases this mark may merely be the line which occurs between dark and light areas of the web as printed. When the eye 33 sees this mark at a time when the printed pattern is very slightly out of registry with the rubber pattern roll, it signals control mechanism 34 which produces a variation in the relative speeds of shafts 45 and 49 of the differential drive. Inasmuch as the general construction and operation of electric eye control mechanisms are well known, there is no need to describe these in detail here.

An important feature of my apparatus comprises the provision of a rubber, or rubber covered, roll having a pattern for the sealing areas of the Wrapper strip cut in relief in its surface. This pattern 25 is shown clearly in FIG. 4 of the drawings, the depth of the relief having been exaggerated. The pattern is cut into the surface as follows: The roll is ground to the desired size, cold, the pattern then cut, the roll then heated up to operating temperature and the heat expansion measured, and finally the pattern is ground off sufiiciently to compensate for the heat expansion. The electrical resistance heater 26 serves to keep the pattern roll at the proper temperature to hold the plastic melt in proper condition for application to the surface of the printed web. A thermostatic control may be provided for this heater. The term rubber as here employed with reference to the material of the pattern roll, or the material of the surface of the roll, is to be understood as including artificial and synthetic heat resistant rubbers, and equivalent resilient materials. I have obtained excellent results with the use of a roll covered with silicone rubber of a hardness of around 50 durometer. While such a material can be molded only with difficulty, I have discovered that it is feasible to cut the pattern in relief using a sharp knife or other suitable tool.

The hot melt applicator roll 61 which transfers the melted adhesive from the reservoir to the surface of the pattern is made with a surface especially adapted to operate in conjunction with a doctor blade 54 so as to apply a measured quantity of the adhesive to the surface of the pattern. In the preferred construction illustrated the hot melt applicator roll is provided with helical grooves 53. These grooves are V-shaped and may comprise, for example, 90% of the area of the surface of the roll. I have had good results with the use of grooves having a depth on the order 0.0032 inch and arranged at an angle of between 30 and 45 with respect to a plane passing through the axis of the roll.

Another important feature of my apparatus resides in the provision of an applicator roll turning in a heated reservoir containing the melted adhesive material, and the particular construction of the reservoir itself. The reservoir is so constructed that the hot melt applicator roll can be most efliciently heated by the hot melted adhesive and also by radiation from the walls of the heated reservoir. In addition the reservoir is constructed with flow passages and galleries which produce a flow of the hot melted adhesive from the reservoir to the applicator roll and thence, in the area of the doctor blade 54, to galleries and passages which convey the hot adhesive around the bearings of the applicator roll to lubricate them, and thence to re-distribute the adhesive to the surface of the applicator roll and to maintain uniformity in temperature throughout the heated reservoir. How these several objectives are accomplished will be understood with reference to FIGS. 6, 7 and 8. The reservoir includes a compartment 55 in which the adhesive is melted down, and a roll compartment 56 of generally cylindrical form closely conforming to the surface of the hot melt applicator roll 61. The compartments 55 and 56 are connected through a passageway 57 extending longitudinally of compartment 56 beneath the roll 61 .and lateral passages 58, 59 at the ends of passageway 57, and lateral passage 63 at the center of the reservoir. Compartment 56 is enlarged at one side of the applicator roll 61, as at 64, providing a place to mount the doctor blade 54 and a gallery 65 for accumulation of excess amounts of the hot melt plastic as delivered by the applicator roll to the area of the doctor blade. From the ends of the gallery 65, the hot melt plastic flows through circumferential channels 66 into the space '67 (FIG. 8) surrounding the bearings 68 for the shaft 69 of applicator roll 61. From the bearings the hot melt can flow through openings 70 and 71 in the end housing 72 which contains the bearing assembly. The stepped down end 73 of roll shaft 69 projects through .a sealed opening in the bearing retainer plate 74 and to this is keyed the sprocket 75 which drives the applicator roll in the manner which has already been described.

The body of the reservoir is provided with a series of cored openings 76 to receive electrical heating elements such as the resistance heaters 77, and one of which may contain a thermocouple 78 providing a thermostatic control of the temperature of the walls of the two compartments of the reservoir. It will be noticed that some of the heating elements are arranged in proximity to the cylindrical surfaces of the roll compartment 56 so that these surfaces will be effectively heated and will in turn heat the applicator roll 61 by radiation, and so that the adhesive will be kept at the right temperature in the space between the surface of the applicator roll and the surface of compartment 56. I have obtained good results with the use of temperatures in the range of about 300 to 400 F. in using commercial grades of hot melt plastic resin adhesives. The clearance between the applicator roll and compartment 56 should be very small so that there will be a minimum amount of plastic at this point to reduce oxidation and keep the adhesive material up to the required temperature. I have found that excellent results can be obtained if this clearance between the applicator roll and its compartment is kept approximately within the limits 0.010 inch to 0.015 inch. The hot melt plastic can be introduced in the form of granules, cakes,

blocks, or otherwise, such as the cakes 79 seen in FIG. 6. The bottoms of compartment 56, passageways 58 and 59, and gallery 65 slope inwardly toward passages 57 and 66, and the bottom of passage 57 slopes inwardly toward the center of the reservoir and the passageway 63. This aids in circulation of the adhesive to maintain uniform temperature throughout and to lubricate the bearings of the applicator roll. Also, the arrangement provides a low point for a drain 80 so that the adhesive may be removed when Operation of the machine is shutdown.

My invention is applicable to both inner and outer wrappings for packages. Such inner wrappings are sometimes referred to as liners, and I wish the terms wrapper and wrapper strip as used herein and in the appended claims, to be understood as including both inner and outer wrappers.

The hot melt adhesives set up rapidly as the wrapper strip is withdrawn from the surface of the pattern roll, and by the time the strip reaches the wrapping machinery, it will be sutficiently hard to avoid problems of sticking to or accumulating upon the surfaces of parts of the wrapping machine. This is helpful from a standpoint of maintenance and avoids difliculties which otherwise would be encountered due to defacing of printed areas of the wrappers. As a result it becomes entirely feasible to mount my apparatus as a unit directly upon existing wrapping machines. In this respect my invention provides advantages not obtainable with the use of thermoplastic resins applied with the use of solvents as distinguished from the melted form. In the wrapping machine heat is applied to soften the adhesive and furnish the required bond. I have found also that a good seal can be obtained with the use of lower pressures and temperatures than would be required in the case of themoplastic adhesives applied to the strip with the use of solvents. An additional advantage of my invention is that it furnishes an extremely simple and effective way for coordinating the operations of producing the heat sealable wrapper strip in continuous lengths with the operation of the wrapping machines which are in general use at this time.

The terms and expressions which I have employed are used in a descriptive and not a limiting sense, and I have no intention of excluding such equivalents of the invention described, or of portions thereof, as fall within the scope of the claims.

I claim:

1. In apparatus for making a heat scalable wrapper strip for delivery to a wrapping machine in continuous lengths as the wrapper strip is being made, means for applying melted adhesive to a pattern roll, said meanscomprising a reservoir for the melted adhesive material, a recess in said reservoir to receive an applicator roll, said recess including cylindrical walls closely surrounding the surface of the applicator roll, and a gallery extending to the side of said recess for accumulation of excess amounts of the melted adhesive material carried out of the cylindrical recess in the reservoir by the applicator roll, said gallery extending to points near the ends of the applicator roll and channels extending from the ends of the gallery to the bearings of the applicator roll by virtue of all of which the melted adhesive is conveyed around the bearings of the applicator roll to lubricate them, and thence ire-distributed to the surface of the applicator roll.

2. In apparatus for making a heat scalable wrapper strip for delivery to a wrapping machine in continuous lengths as the wrapper strip is being made, means for applying melted adhesive to a pattern roll, said means comprising a reservoir for the melted adhesive material, a recess in said reservoir to receive an applicator roll, said recess including cylindrical walls closely surrounding the surface of the applicator roll, means disposed adjacent said cylindrical walls for heating the adhesive lying Within the space where the cylindrical walls closely surround the surface of the applicator roll and for heating the applicator roll by radiation from the cylindrical walls,

and a gallery extending to the side of said recess for accumulation of excess amounts of the melted adhesive material carried out of the cylindrical recess in the reservoir by the applicator roll, said gallery extending to points near the ends of the applicator roll and channels extending from the ends of the gallery to the bearings of the applicator roll by virtue of all of which the melted adhesive is conveyed around the bearings of the applicator roll to lubricate them, and thence re-distributed to the surface of the applicator roll for heating and to maintain 10 uniformity in temperature throughout the reservoir.

References Cited in the file of this patent UNITED STATES PATENTS Allen Jan. 4, 1898 Sevigne Dec. 6, 1921 Sturm Dec. 23, 1952 Pavlic May 26, 1953 Zinn Nov. 17, 1953 Scholl Jan. 3, 1956 Harmon 'Feb. 12, 1957 Kelly Apr. 2, 1,957

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,030,915 April 24, 1962 Arthur Vernon Shannon It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the nt, line 1, name of inventor, for 'Arthur Vernon Channon" read Arthur Vernon Shannon column 6 line 34, for "themoplastic" read thermoplastic line 3, for "space" read spaces Signed and sealed this 25th day of September 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID D Attesfing Office Commissioner of Patents

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