US3323936A - Coating and impregnating apparatus and method - Google Patents

Description

June 6, 1967 Filed Nov. 12,

l. L. TOLF COATING AND IMPREGNATING APPARATUS AND METHOD 2 Sheets-Sheet 1 INVENTOR INGVAR L. TOLF MMHE aul,

ATTORNEYS June 6, 1967 TOLF 3,323,936

COATING AND IMPREGNATING APPARATUS AND METHOD Filed Nov. 12. 1963 2 Sheets-Sheet 2 v FIG.4

United States Patent Ofifice 3,323,936 Patented June 6, 1967 3,323,936 COATING ADID INIPREGNATING APPARATUS AND METHOD Ingvar L. Tolf, Battle Creek, Mich, assignor to General Foods Corporation, White Plains, N.Y., a corporation of Delaware Filed Nov. 12, 1963, Ser. No. 322,882 Claims. (Cl. 117-44) This application relates to a novel method for coating a carton structure as well as an apparatus by means of which the novel method can be effectively carried out. More particularly, it is directed to such a method and apparatus for coating and impregnating a free edge of a carton suitable for use in dispensing web materials.

Cartons which are particularly formed so that they will retain a roll of web material, such as waxed paper, metal foil and other films, are well-known. The roll ordinarily is located within the body of the carton, and the carton, as erected, contains an elongated groove through which the leading edge of the roll projects. This leading edge may be grasped and pulled to rotate the roll and dispose portions thereof outside the carton. After a desired length of the web has been pulled from within the carton, the pulled web is severed from the remainder of the roll, commonly by disposing the sheet or web against a cutting edge formed in the carton and tearing the sheet in contact with that edge. Most commonly, the cutting edge is composed of a strip of metal, generally serrated, and the foil, paper or other material .is pressed against the hard, metal edge, causing the web to tear along the edge. In this manner, a desired length of the roll material is separated from the remainder of the roll.

Cartons for dispensing web materials are generally formed from paperboard and like cellulosic stock, conventionally from a laminated structure composed of plies of paperboard, paper and/or'foil. Since the stock, itself, is inherently too weak to serve as an effective cutting edge, a metal strip must be attached to the board structure. Such attachment ordinarily takes place after formation of the carton blank, and requires a separate operation in addition to the formation of the blank, which acquires its particular shape by the cutting and scoring of a continuous web of carton blank stock. The metal strip, itself, and its application to the carton blank adds considerably to the cost of that blank. In addition, complex and expensive equipment is required to affix the metal strip to the blank. It has thus been found desirable to eliminate the necessity of utilizing a separate metal strip to form a cutting edge and, instead, using a part of the carton, itself, for this purpose.

In order to overcome the economic disadvantages in providing a serrated, metallic strip to form a cutting edge, attempts have been made to find other means of hardening or reinforcing a free edge of the carton and carton blank from which the container for the roll of web material is made. Reinforcement of a free cutting edge which is not formed from metal or some other hard metal is necessary because, after a multiplicity of uses of an unreinforced cutting edge, the exposed plies of paperboard at the free edge tend to become separated and frayed, with a consequent breakdown of the form of the edge. A malformed edge results in a poor cut of the web material contained within the carton and, finally, in the inability of the edge to form a surface along which the web can be severed.

It is, therefore, a primaryobject of the present invention to provide an apparatus which will continually and at high speed apply to a free edge of a carton blank to be used as a cutting edge, a reinforcing fluid that, when hardened, will impart increased hardness to the free edge to which it has been applied. It is another object to provide a method for using this apparatus.

It is still another object of the present invention to provide an apparatus and method for coating and impregnating a free edge of a carton blank to be utilized as a cutting edge, which apparatus and method will effectively coat and impregnate a serrated free edge of the blank and which will utilize quantities of coating material applied .in excess of those actually used by recovering excess material and recycling it for further application to other carton blanks.

According to the present invention, my apparatus for coating and impregnating a free edge of a blank of paperboard and the like with a thermoplastic material is basically formed from two guides. A top guide has a face extending along its lower surface, and a bottom guide, positioned generally beneath the top guide, is formed with a face extending along its upper surface. These upper and lower surfaces are generally in vertical alignment and opposed to each other so that they form an elongated slot between them. In the top guide is an orifice for conducting molten thermoplastic material to the slot and onto the free edge of a blank in the slot, which has a thickness approximating that of the blank, itself. The orifice preferably terminates at the face of the lower surface of the top guide, so that the thermoplastic agent can be forced directly into the slot. In an important embodiment of the apparatus, a guide spacer is provided with a wall adjacent to the slot, and this wall defines an inward limit of the slot.

It has been found preferable that the bottom guide be formed with a groove in its upper surface face and below the terminus of the orifice in the lower surface face of the top guide. This groove, which may be in the shape of a vertical section of an inverted cone, serves to conduct excess molten thermoplastic material issuing from the orifice terminus away from the slot. When the free edge portion of the blank is formed with teeth, excess thermoplastic material passes through the teeth into the groove.

In order that the apparatus of the present invention will operate continuously and at high speed, an applicator head is preferably provided to feed molten thermoplastic material to the slot into which carton blanks are fed. The applicator head is connected to a reservoir for retaining thermoplastic material, and appropriate means urges molten thermoplastic material in the reservoir through the head and then through and from the orifice.

Under the bottom guide that, together with the top guide, forms the slot, 2. return trough is mounted, so that material flows into the trough. This thermoplastic material is heated and directed to the reservoir and thence to the orifice for reuse in coating and impregnating the free, serrated edge portion of a blank.

By the method employed according to the present invention, a free edge portion of a carton blank is coated and impregnated simultaneously. As the slot has a thickness which approximates that of the free edge portion of the carton blank disposed therein, impregnation is'not only accomplished by the direct application of thermoplastic material under pressure onto the free edge portion, but is also accomplished by the fact that, since the thicknesses of the slot and blank are about the same, the thermoplastic material on the free edge will be squeezed into the board as the coated portion moves further into the restricted opening of the slot. 7

The coating operation of the edge portion and subsequent squeezing of thermoplastic material into that portion is emphasized when a groove is located directly under the discharge orifice for the material. In such a case, the edge is not supported directly under the orifice, so that thermoplastic material issuing under pressure from the orifice will be forced against the teeth of the serrated edge and then some of the material will flow past the teeth into the groove therebelow. The material remainingon the serrated edge and between the teeth will be forced into the paperboard as the edge moves further through the slot to locations where the top and bottom guides are continuous. The process is improved by recovery of the excess material from the groove in the bottom guide and subsequent heating and recycling of the material.

These and other objects and features of the present invention will be better understood by reference to the illustration of a preferred embodiment of my apparatus in the accompanying drawings, which form a part hereof, and in which:

FIGURE 1 is a side elevation, partly in section, of the applicator head and attachments with a carton blank in coating and impregnating position;

FIGURE 2 is a top plan view, partly in section, of the apparatus illustrated in FIG. 1;

FIGURE 3 is a front elevation showing details of the guide of my invention, and

FIGURE 4 is a perspective view of the apparatus illustrated in FIGS. 1 to 3 and accessory equipment for coating and impregnating carton blanks as Well as recovering excess coating material.

Referring now to the drawings, and in particular to FIG. 4 thereof, the apparatus of the present invention basically comprises an applicator head rigidly connected to top guide 11 and bottom guide 12 in such a manner that these guides are spaced apart to provide an elongated slot 13 between them. A carton blank 14 is directed into the slot 13 with the serrated edge 15 of the carton blank disposed so that it will lie within the slot 13. Thermoplastic material is applied to the serrated edge 15 in slot 13, excess material passing into groove 16 in bottom guide 12 and thence into a heated trough 17. The material passes through the trough and from spout 18 into a reservoir 19, from which it is forced back into the applicator head 10 by connecting tubing 20.

Important features of the applicator head 10, top guide 11 and bottom guide 12 are best illustrated inFIGS. 1 to 3. In FIG. 1, for example, it will be seen that the'applicator head 10 is held in place by means of a clamp bracket 46, see FIG. 4, the applicator head extending with its axis in a generally horizontal plane. In an upper portion of generally circular applicator head 10, an orifice 23 extends in a generally horizontal direction throughout the length of the head. Orifice 23 passes through guide spacer 24 and into top guide 11, whence its direction is changed by a vertically downward exten sion ZS ter-m'inating' in the face 26 on the lower surface of top guide 11. Terminus 28 of orifice 23 is shown in FIGS. 1 and 3. Bore 22 is provided to retain a heating element, if necessary.

Between them top guide 11 and bottom guide 12 form a slot 13, the slot being bounded by face 26 of top guide 11 and face 31 of bottom guide 12. The relation of these faces is best illustrated in FIG. 3. As is there shown, the slot 13 is formed with a flared opening 32 to receive a carton blank 14, and the guides are held in place on the applicator head 10 by screws 33. In its position, guide spacer 24 has a wall 35 that forms the innermost limit to which carton blank 14 may be pushed in the slot 13. The position of the serrated edge 15 of the carton blank 14 pressed against wall 35 of guide spacer 24 is well shown in FIG. 2. In such position, it will be seen that the teeth of edge 15 are covered by and lie wholly within the top guide 11.

A groove 16 in the bottom guide 12 of the apparatus is a feature of the preferred embodiment of the invention. As illustrated in FIGS. 3 and 4, groove 16 lies directly beneath terminus 28 of orifice extension 25, and is somewhat wider than the terminus. In such location, the groove, which most preferably is in the form of a vertical section of an inverted cone having its base in the plane of face 31, is positioned to receive excess thermoplastic material 4 issuing from terminus 28. From the groove 16 this excess thermoplastic material, which has passed' between the teeth of serrated edge 15 of carton blank 14, drips into trough 17, which may be heated by conventional equipment (not shown) in case the ambient temperature is such that the thermoplastic material will solidify in trough 17. From trough 17, the molten material flows from spout 18 into reservoir 19 past a screen 37 in the top of the reservoir. From reservoir 19 the thermoplastic material is pumped by conventional means incorporated therewith through connecting tubing 20 back into applicator head 10.

Also illustrated in FIG. 4 is equipment by means of which the applicator head 10 and top and bottom guides 11 and 12 are mounted. Thus, clamp 40, which is securely fixed to frame member 41, acts as a stanchion for vertical rod 42, which has an end 43 fixed in upper clamp 44 by means of horizontal rod 45 and clamp bracket 46. The applicator head 10 is rigidly mounted by clamp bracket 46 to support guides 11 and 1 2 fixed to it as well as guide spacer 24.

The method of .the present invention will also be better understood by reference to the drawings of the apparatus of the invention. According to my method, thermoplastic material is directed under pressure to orifice 23, orifice extension 25 and from terminus 28. By virtue of such pressure ejection, the thermoplastic material is forced against serrated edge 15 of blank 14, and some of the material flows between the serrations and into the groove 16. A carton blank 14 is not supported directly beneath terminus 28 of orifice 23 because of groove 16, but the speed of passage of carton blanks 14 through slot 13 is so rapid that this temporary discontinuity in upper face 31 of bottom guide 12 has no ill effect on the carton blanks and causes no rupture of teeth therein. Because of the same speed, thermoplastic material between the serrations of edge 15 does not remain there. With thermoplastic material applied on and between the teeth of edge 15 at terminus 28, the coated part of the free edge portion then passes further in slot 13 to locations where the upper surface 31 is once more continuous. Material remaining on the surface of the free edge portion of blank 14 will, at these locations, be pressed into the paperboard stock of which the blank is formed, thus impregnating the free, serrated edge portion of the blank.

Thermoplastic agent which is utilized to coat and impregnate the free edge may be selected from many thermoplastic materials. It will advantageously contain polyethylene and a hydrocarbon wax. Preferably, the wax is in an amorphous rather than crystalline form and may fur- .ther be combined with a hydrocarbon resin, such as Piccolyte-70, a product of Pennsylvania Industrial Chemical Corporation. Typical waxes are manufactured by Sun Oil Company and identified by trademarks 1290 and 985. Polyethylene which has been utilized is one identified by the mark AC-6 and is manufactured by Allied Chemical Corporation.

The melting point of the thermoplastic composition which is applied to the carton stock is advantageously adjusted to about 190 F., and within a range of about to 205 F. This range is obtained by blending polyethylene AC-6 (melting point 219 to 226 F. and molecular weight about 2000) with microwax 1290 (melting point 178 F.) and microwax 985 (melting point 193 F.) as well as Piccolyte-70 (melting point about B). One formula that has been found particularly useful is a blend of approximately equal parts of hydrocarbon resin, microwax and polyethylene, microwax 1290 being present in about three times the amount of microwax 985.

In practice, the molten thermoplastic material has been applied at a temperature of about 385 F.:15 Preferably, the hot melt composition should be applied at as high a temperature as possible, since it should be tions tend to be stringy at temperatures not sufficiently above their melting points. Toohigh a temperature of the thermoplastic material, however, may result in oxidation of the blend so that it becomes undesirably odorous and tends to lose some of its properties. In order to avoid the development of oif odors, the pot life of .the thermoplastic material should generally be limited to not more than one hour, since extended pot life will result in the development of unfavorable properties in the molten material.

It will be apparent that certain alterations and modifications in the apparatus and method described hereinbefore will be obvious to those skilled in the art without departing from .the scope of the present invention. All such obvious alterations and modifications are, therefore, deemed to be included within the purview of my invention, which isto be limited only by the scope of the following, appended claims.

I claim:

1. Apparatus for coating and impregnating a free edge portion of a blank of paperboard and the like with a thermoplastic material, comprising a top guide formed with a face extending along a lower surface thereof, a bottom guide positioned generally beneath said top guide and formed with a face extending along an upper surface thereof, said lower and upper surfaces being in general vertical alignment and opposed to each other so that they form an elongated slot between them, said slot having a width approximating the thickness of said blank at said free edge portion, the face of one of said guides having formed therein an orifice for conducting molten thermoplastic material pumped at a predetermined pressure to said slot and onto said free edge portion therein, and a guide spacer to which said top and bottom guides are fixed with said opposed faces spaced from each other, said guide spacer having a wall adjacent to said slot and defining an inward continuous limit thereof.

2. Apparatus for coating and impregnating a free edge portion of a blank of paperboard and the like with a thermoplastic material, comprising a top guide formed with a face extending along a lower surface thereof, and a bottom guide positioned generally beneath said top guide and formed with a face extending along an upper surface thereof, said lower and upper surfaces being in general vertical alignment and opposed to each other so that they form an elongated slot between them, said slot having a width approximating the thickness of said blank at said free edge portion, said .top guide having formed therein an orifice terminating at said lower surface face for conducting molten thermoplastic material to said slot and onto said free edge portion there-in, said bottom guide having formed therein a groove terminating at said upper surface face and below the terminus of said orifice for conducting excess molten thermoplastic material away from said slot.

3. Apparatus as claimed in claim 2, in which said groove has the shape of a vertical section of an inverted cone, the base of said cone lying in the plane of said upper surface face.

4. Apparatus for coating and impregnating a free, serrated edge portion of a blank of paperboard and the like with a thermoplastic material, comprising a top guide formed with a face extending along a lower surface thereof, a bottom guide positioned generally beneath said top guide and formed with a face extending along an upper surface thereof, said lower and upper surfaces being in general vertical alignment and opposed to each other so that they form an elongated slot between them, said slot having a width approximating the thickness of said blank at said free edge portion, said top guide having formed therein an orifice terminating at said lower surface face for conducting molten thermoplastic material to said slot and onto said free edge portion therein, said bottom guide having formed therein a groove terminating at said upper surface face and below the terminus of said orifice for conducting excess molten thermoplastic material away from said slot, and means for feeding blanks into said slot so that said serrated edge portion is disposed between said faces and for urging said serrated edge past said orifice terminus and said groove.

5. Apparatus for coating and impregnating a free edge portion of a blank of paperboard and the like with a thermoplastic material, comprising a top guide formed with a face extending along a lower surface thereof, a

bottom guide positioned generally beneath said top guide and formed with a face extending along an upper surface thereof, said lower and upper surfaces being in general vertical alignment and opposed to each other so that they form an elongated slot between them, said slot having a width approximating the thickness of said blank at said free edge portion, said top guide having formed therein an orifice for conducting molten thermoplastic material to said slot and onto said free edge portion therein, a guide spacer attached to said guides and forming a continuous inward limit for said slot, an applicator head having a passageway for molten thermoplastic material and connecting with said orifice, a reservoir for retaining said material, means connecting said reservoir and said passageway, and means incorporated with said reservoir for urging molten thermoplastic material in said reservoir through said connecting means into said passageway and through said orifice at a predetermined pressure to impregnate the free edge portion of a blank disposed within said slot.

6. Apparatus for coating and impregnating a free edge portion of a blank of paperboard and the like with a thermoplastic material, comprising a top guide formed with a face extending along a lower surface thereof, a bottom guide positioned generally beneath said top guide and formed with a face extending along an upper surface thereof, said lower and upper surfaces being in general vertical alignment and opposed to each other so that they form an elongated slot between them, said slot having a width approximating the thickness of said blank at said free edge portion, said top guide having formed therein an orifice terminating at said lower surface face for conducting molten thermoplastic material to said slot and onto said free edge portion therein, said bottom guide having formed therein a groove terminating at said upper surface face and below the terminus of said orifice for conducting excess molten thermoplastic material away from said slot, an applicator head having a passageway connecting with said orifice, a reservoir for retaining said material, means connecting said reservoir and said passageway, means urging molten thermoplastic material in said reservoir through said connecting means into said passageway and through and from said orifice, a return trough mounted below said groove for receiving said excess material therefrom, and means for directing said material from said trough to said reservoir.

7. A method of impregnating and coating a free, serrated edge of a blank of paperboard and the like with a thermoplastic material, comprising moving said blank into an elongated slot so that said edge is disposed at said slot, said slot having a thickness approximating the thickness of said blank at said edge, forcing thermoplastic material onto said edge and between the teeth thereof when said edge is at said slot, and continuing to move said edge through said slot to squeeze said material into said paperboard at said edge.

8. A method of impregnating and coating a free, serrated edge of a blank of paperboard and the like with a thermoplastic material, comprising moving said blank into an elongated slot so that said edge is disposed within said slot, said slot having a thickness approximating the thickness of said blank at said edge, forcing thermoplastic material through an orifice in one face of said slot onto said edge and between the teeth thereof when said edge is in said slot, and continuing to move said edge through said slot to squeeze said material into said paperboard at said edge.

9. A method of impregnating and coating a free, serrated edge of a blank of paperboard and the like with a thermoplastic material, comprising moving said blank into an elongated slot so that said edge is disposed within said slot, said slot having a thickness approximating that of said blank at said edge, forcing thermoplastic material through an orifice in an upper wall of said slot onto said edge and between the teeth thereof when said edge is in said slot, supporting said blank during forcing of said material by means of a bottom wall of said slot discontinuous directly beneath said orifice, and continuing to move said edge through said slot to squeeze said material into said paperboard at said edge.

10. A method of impregnating and coating a free, serrated edge of a blank of paperboard and the like with a thermoplastic material, comprising moving said blank toward an elongated slot so that successive portions of said edge are disposed within said slot, said slot having a thickness approximating that of said blank at said edge,- 7 forcing thermoplastic material through an orifice in an upper Wall of said slot onto said successive portions of said edge and between the teeth thereof, supporting said blank during forcing of said material by means of a bottom wall of said slot discontinuous directly beneath said orifice, continuing to move said edge through said slot to squeeze said material into said paperboard at said edge, recovering the excess material that passes from said orifice between said teeth and through said discontinuous bottom wall, and recycling said excess material back to said orifice.

References Cited UNITED STATES PATENTS 2,016,316 10/1935 Collins 11743 ALFRED L. LEAVI'IT, Primary Examiner.

ALAN GRIMALDI, Assistant Examiner.

Claims (2)

1. APPARATUS FOR COATING AND IMPREGNATING A FREE EDGE PORTION OF A BLANK OF PAPERBOARD AND THE LIKE WITH A THERMOPLASTIC MATERIAL, COMPRISING A TOP GUIDE FORMED WITH A FACE EXTENDING ALONG A LOWER SURFACE THEREOF, A BOTTOM GUIDE POSITIONED GENERALLY BENEATH SAID TOP GUIDE AND FORMED WITH A FACE EXTENDING ALONG AN UPPER SURFACE THEREOF, SAID LOWER AND UPPER SURFACES BEING IN GENERAL VERTICAL ALIGNMENT AND OPPOSED TO EACH OTHER SO THAT THEY FORM AN ELONGATED SLOT BETWEEN THEM, SAID SLOT HAVING A WIDTH APPROXIMATING THE THICKNESS OF SAID BLANK AT SAID FREE EDGE PORTION, THE FACE OF ONE OF SAID GUIDES HAVING FORMED THEREIN AN ORIFICE FOR CONDUCTING MOLTEN THERMOPLASTIC MATERIAL PUMPED AT A PREDETERMINED PRESSURE TO SAID SLOT AND ONTO SAID FREE EDGE PORTION THEREIN, AND A GUIDE SPACER TO WHICH SAID TOP AND BOTTOM GUIDES ARE FIXED WITH SAID OPPOSED FACES SPACED FROM EACH OTHER, SAID GUIDE SPACER HAVING A WALL ADJACENT TO SAID SLOT AND DEFINING AN INWARD CONTINUOUS LIMIT THEREOF.

7. A METHOD OF IMPREGNATING AND COATING A FREE, SERRATED EDGE OF A BLANK OF PAPERBOARD AND THE LIKE WITH A THERMOPLASTIC MATERIAL, COMPRISING MOVING SAID BLANK INTO AN ELONGATED SLOT SO THAT SAID EDGE IS DISPOSED AT SAID SLOT, SAID SLOT HAVING A THICKNESS APPROXMATING THE THICK-

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