US3567111A

US3567111A - Multiply paper bag

Info

Publication number: US3567111A
Application number: US818909A
Authority: US
Inventors: Robert O Baxter; Clint R Hollis; Carlton F Evans
Original assignee: International Paper Co
Current assignee: International Paper Co
Priority date: 1969-04-24
Filing date: 1969-04-24
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02
Also published as: JPS51918B1

Abstract

A multiply paper bag in which the inner wall of the inner ply is coated with a heat sealable moistureproof material and the end of the bag is folded, sealed and taped to form a leakproof closure. Apparatus for the manufacture of such bags having means for advancing bag blanks one after the other along a path, means along the path for heating the bottom end of the blank to soften the thermoplastic coating, means for applying a sealing force to the softened thermoplastic coating, means for holding the seal while the thermoplastic coating cools and hardens, means for embossing the bag blank along a fold line for folding the bag blank end along the fold line and for folding the folded portion into the sidewall of the blank and means for applying, coating and adhesively securing a tape to the folded portion and the sidewall of the blank.

Description

United States Patent inventors Appl. No. Filed Patented Assignee MULTIPLY PAPER BAG 10 Claims, 47 Drawing Figs.

US. Cl 229/57,

Int. Cl. B6511 33/02 Field of Search 229/57, 55, l 62; 93/8, 62

{111 3,567,1lll

Primary Examiner-David M. Bockenek Attorney-Charles B. Smith ABSTRACT: A multiply paper bag in which the inner wall of the inner ply is coated with a heat scalable moistureproof material and the end of the bag is folded, sealed and taped to form a leakproof closure. Apparatus for the manufacture of such bags having means for advancing bag blanks one after the other along a path, means along the path for heating the bottom end of the blank to soften the thermoplastic coating, means for applying a sealing force to the softened thermoplastic coating, means for holding the seal while the thermoplastic coating cools and hardens, means for embossing the bag blank along a fold line for folding the bag blank end along the fold line and for folding the folded portion into the sidewall of the blank and means for applying, coating and adhesively securing a tape to the folded portion and the sidewall of the blank.

PATENTEB MAR 2 l9?! SHEET 02 0F 14 SHEET PATENTED MR 2 Ian SHEET PATENTED MAR 2 I971 PATENTED mm m SHEET 1 1 [JF PATENTED MAR 2 IHYI SHEET 12 HF PATENTED MAR 21m SHEET 1B OF 14 MULTIIIP'LY PAPER BAG Ieakproof closure and to apparatus for the manufacture of such bags.

The use of paper bags for the disposal of garbage, trash, rubbish and refuse from homes, hospitals, institutions, and the like, has many advantages. In many areas, local health and sanitation ordinances require that garbage and trash be wrapped. Such wrapping, among other things eliminates soiled cans, the banging and hammering of the cans, easier handling of the garbage and rubbish, and has a number of other ad vantages. Mere wrapping of the garbage and rubbish does not, however, in allinstances attain such advantages because, if the wrapping opens up or fails before the garbage and trash is collected and disposed, these advantages are not always attained. Thus, in some areas, particularly in hospitals and institutions disposable, waterproof containers are specified for garbage, trash and waste. In addition to being waterproof, such containers must also have certain strengths so that, when filled, the container will not rip, open up or fail and spill its contents and so that, when filled, the container might be handled, such as in the handling required in picking up and, disposing of the filled container in an incinerator, or the like.

Various attempts have, heretofore, been made to provide an acceptable container for garbage, trash and the like. Such containers have included an inner paper ply coated on its inner surface so that the inner surface is waterproof and an outer ply treated with a material to render the outer surface repellent to atmospheric moisture, such as rain, snow and the like. One of the difficulties heretofore encountered in the making of such containers has been to provide an enclosure which is waterproof and sufficiently strong to support the weight of the garbage, trash and waste and handling. Some of such bags, in order to attain the necessary strength, have been sewed or stitched. Because such sewing and stitchingrequires perforation of the various plies and, at such perforations, have exposed the paper to wicking and wetting either from the interior or exterior of the bag, such bags, where the ends are sewn, have not been completely satisfactory. Furthermore, the sewing or stitching of the end closure has added to the cost of the bag.

The instant invention is concerned with an improved paper bag for garbage, trash and waste in which the bottom end of the bag is heat sealed, creased and folded and a tape of predetermined length is applied to the end of the bag over the end of the folded portion to reinforce the end closure and prevent wicking or wetting of the bottom through the exposed edges of the plies. In heat sealing the end prior to creasing and folding, the opposite walls of the inner ply are sealed along a line which, when the bag is folded, is along a line extending widthwise of the bag spacedupwardly of the folded portion away from the fold line. Thus, at the fold line, where the bottom of the bag is creased, the inner wall of the inner ply, at the creased line, can expand without rupturing, tearing,or breaking the waterproof coating on the inner surface of the inner ply. This is important because, as has been noted above, wicking or wetting of the bag at the bottom weakens the bag end and results in ripping, tearing and rupturing of the bag bottom which, when it occurs, spills the bag's contents.

The instant invention is also concerned with a machine for producing such a bag. In the machine, the end of the bag is heated, softening the thermoplastic coating on the inner wall of the inner ply. After the coating has been softened, the end of the bag is sealed along a line which, after the bag is folded will be between the fold crease and the .bag end. The bag, after it is sealed, is creased along a line above the seal line, away from the end, and the end is folded at the crease and the tape is supplied over the fold end and adhesively secured over the fold edge.

The instant invention would be better understood from the following description and appended drawings in which:

FIG. 1 is a perspective view, partially broken away, of a 2- ply sheet used in forming the bag of the instant invention;

FIG. 2 is a perspective view of the sheet of FIG. 1 formed into a tube with the end open;

FIG. 3 is a perspective view of the bag of the instant invention with the end sealed, creased, folded and the tape applied;

FIG. 4 is an end view of the tab tube of FIG. 2;

FIG. 5 is a side elevational view of the bag of the instant invention;

FIGS. 6 to 13 are top plan views of the bag at the various stages of formation of the bag end closure;

FIGS. 14a, b and c are side elevational views of the machine for making the bag'of the instant invention, a portion of the machine being shown, inside elevation in each of the FIGS.;

FIGS. 15a and 15b are top plan views, with sections broken away, of the machine of FIGS. 14a, b and 0;

FIG. 16 is a side elevational view, in enlarged detail, taken at line 16-16, FIG. 15a;

FIG. 17 is a cross-sectional view taken at line 17-17, FIG. 16;

FIG. 18 is an enlarged end view, partly in section, taken at line 18-18, FIGL14a;

FIG. 19 is an enlarged end view, partly in section, taken at line 19-19, FIG. 14b;

FIG. 20 is a side elevational view, taken at line 20-20, FIG. 19;

FIG. 21 is a view, taken at line 21-21, FIG. 20;

FIG. 22 is a cross sectional view of the bag end, taken at line 22-22, FIG. 8;

FIG. 23 is a view, partially broken away and in section taken at line 23-23, FIG.

FIG. 24 is a side elevational view taken at line 24-24, FIG. 23;

FIG. 25 is a view taken at line 25-25, FIG. 14c;

FIG. 26 is a side elevational view taken at line 26-26,.FIG. 25;

FIG. 27 is an enlarged end view, partly in section of the driving roll of FIG. 25;

FIG. 28 is an enlarged view of the bag taken at line 28-28, FIG. 9;

' FIG. 29 is a side elevational view taken at line 29-29, FIG. 15b;

FIGS. 30, 31, 32, 33 and 34 are views taken at lines 30-30, 31-31, 32-32, 33-33 and 34-34, respectively, FIG. 29;

FIG. 35 is a view taken at line 35-35, FIG. 140;

FIG. 36 is a cross-sectional view of the bag end taken at line 36-36, FIG. 11;

FIG. 37 is an enlarged side elevational view of the tape application taken at line 37-37, FIG. 15b,-

FIG. 38 is a view of the tape application rolls and knife taken at line 38-38, FIG. 37;

FIG. 39 is a view of the tape guide taken at line 39-39, FIG. 37; a

FIG. 40 is a cross-sectional view of the tape guide taken at line 40-40, FIG. 39;

FIG. 41 is an enlarged view, in cross section, of the bag end' taken at line 41-40, FIG. 12; and

FIGS. 42, 43 and 44 are enlarged views, broken away, of the tape applicator rolls, knife and tape brake showing various positions of the tape applicator units at various stages of operation.

Referring to FIGS. 1, 2 and 4, the bag of the instant invention includes outer ply sheet 2 and inner ply sheet 4 of approximately the same length and width ovcrlayed, one over the other, with their longitudinal edges staggered so that, when longitudinally folded along

lines

6, 8 and 10, and 12, 14 and 16 with longitudinal edges 2', 2" of outer ply sheet 2 and iongitudinal edges 4', 4" of inner ply sheet 4 overlapped, the Iongitudinal seams thus formed and adhesi'vely secured together, as on a conventional tubing machine, are staggered as best shown in FIGS. 2 and t.

The outer surface of outer ply sheet 2 which, when the sheets are overlayed, one over the other, and longitudinally folded and seamed, forms the outer surface of the tubed plies is treated with a water repellent material so that, if exposed to the elements, such as rain, snow and the like, the outer surface of outer ply sheet 2 will shed water. The inner surface of inner ply sheet 4 is coated with a thermoplastic film, such as polyethylene, in a conventional manner. In coating the inner surface of inner ply sheet 4, a heavy coating of thermoplastic is not required, so long as the coating bars water from reaching the paper for reasons more apparent hereinafter. Before inner ply sheet 4 is laid over outer ply sheet 2, a water resistant adhesive is applied to the inner surface of outer ply sheet 2 along a discontinuous line of dots 18 about inch from the bottom edge of the sheet and blocks 20 about inch from the bottom. In addition, a discontinuous line of dots 22 of water resistant adhesive is applied about 3 inches from the bottom edge of outer ply sheet 2 between fold line and the sheet edge and dots 24 between fold line 16 and the sheet edge. Because such adhesive is water resistant and the opposing faces of

sheets

2, 4 are wettable, when the sheets are brought together, the adhesive dots and blocks adhesively secure the sheets together and hold the sheets in alignment for further handling.

Referring to FIGS. 14a, 14b, 14c and a and 15b, the ap paratus for producing the closed end bag of the instant invention includes frame 32 on which are mounted a heating section, generally designated 34, a sealing section, generally designated 36, a creasing and folding section, generally designated 38, and a taping section, generally designated 40. Sprockets 42, 44 are keyed to

shafts

46, 48 mounted for rotation, in suitable hearings, in

supports

50, 52 on frame 32. At the opposite end of heating and sealing

sections

34, 36, sprockets 54, 56 are keyed to

shafts

58, 60 mounted for rotation, in suitable bearings, in supports 62, 64. Chain 66 passes, in an endless loop, around

sprockets

42, 54 and chain 68 passes, in a similar manner around sprockets 44, 56. For reasons more apparent hereinafter, bag supporting table 70. FIGS. 15a and 15b, is supported on frame 32, in alignment with opposing

chains

66, 68, and supports the bags as the bag ends are heated, sealed, folded and taped as such bags move from the left to the right of the machine as such machine is viewed in FIGS. 14a, 14b, 140, 15a and 15b. The end of such bag is gripped between, and the bag is fed by, opposing

chains

66, 68 in a manner later described and to assist

chains

66, 68 in-feeding such bags and to maintain the ends of the bags in alignment in the heating and sealing sections and parallel with each other, such bags are supported on endless chain 72, projecting upward through slot 74 in supporting table 70, chain 72 passing, at one of its ends, around sprocket 76 keyed to shaft 48 and, at its other end, around sprocket 78 keyed to shaft 60.

As best shown in FIGS. 14a, 14b, 16, 17 and 18, heater sec tion 34 includes upper heater, generally designated 81) and lower heater, generally designated 82, mounted on frame 32 by a plurality of supports 84 spaced substantially equidistant along frame 32. With particular reference to FIGS. 16, 17 and 18, upper chain guide 86 having fastened thereto upper heater element stop 88 is mounted on bracket 90 fixed to one end of spring support 92, spring support 92 being fixed, at its opposite end to support 84. Lower chain guide 94 is fixed to bracket 94 having heater element support 96 affixed thereto is mounted on bracket 98 attached to lower arm 100 of support 84, lower element 100 of support 84 mounting such support on frame 32. Chain guide 94 guiding and supporting chain 68 is rigidly mounted on support element 100 while chain guide 86 of upper chain 66 is spring supported by spring support 92. Thus, the opposing faces of

chains

66, 68 are spring urged by leaf spring support 92 toward each other thereby gripping the paper bag positioned therebetween, as shown in phantom lines in FIG. 17. Upper heater head 102 having a downwardly pro.- jecting heat sink 104 and a heater unit, such as 106 extending axially along heater section 34 is mounted by support 108 on leaf spring 110, the end of leaf spring 110 being fixed to clamp 112 fixed by clamping screw 114 to shaft 116 for reasons more apparent hereinafter. Heat shield 118 mounted on support 108 extends around upper heater head 102. Lower heater head 120 having upwardly extending heat sink 122 and a heater element, such as electrical element 124 extending axially thereof is mounted by support 126 on leaf spring 128 fastened at its opposite end to clamp 130 fixed by clamping screw 132 to shaft 134.

Shafts

116 and 134 extend axially along heater section 34 and are rotatably supported on supports 84 by brackets 136.

As best shown in FIG. 18, gear 138 is fixed to shaft 116 and gear 140 mating with gear 138 is fixed to shaft 134. Cylinder 141), FIG. 18, is pivotally mounted on frame 34 and piston rod 142 of cylinder 140 is connected by clevis 144 to arm 146 clamped by clamping screw 148 to shaft 134. Cylinder 140 and piston 142 through arm 146 and mating gears 138, 140 rotate

shafts

116, 134 to rotate heater heads 102, 120 from the position shown in full line in FIG. 17 to the position shown in phantom line and vice versa. When in full line position, the ends of

springs

110, 128 engage stops 88, 96, respectively, such stops, in cooperation with leaf spring support 92

spacing heat sinks

104, 122 from the opposite sides of the paper bag passing therebetween.

Referring now to FIGS. 14b, 15a, 19, 20, 21 and 22, sealing section 36 includes support 150 fixed to frame 32 and rotatably supporting mating gears 152, 154 and mating gears 156, 158 and idler gear 160 mounted between gears 154, 158. Gears 152, 154, 156, 158 are keyed, respectively, to

shafts

162, 164, 166, 168,

shafts

164, 168 being rotatably supported, in fixed position on support 150 and

shafts

162, 164 being mounted, respectively, in blocks 170, 172 slidably mounted in support 150 and urged downwardly, for reasons more apparent hereinafter, by springs 174, 176. Pressure wheels 178, are mounted on

shafts

162, 166, respectively, and sealing wheels 182, 184 are mounted on

shafts

164, 166, respectively.

Referring to FIG. 21, sealing wheels 182, 184 are identical each having an inner element 186 fixed to the shaft by setscrew 188, outer element 190 fixed to the shaft by setscrew 192 and intermediate element 194 having an outer rounded surface 196 projecting outwardly beyond elements 186, 190 and rotatably supported on the shaft by bearings 198, 200. The outer surfaces of elements 186, 190 are knurled for reasons more apparent hereinafter.

As best shown in FIGS. 14b, 14c, 15a, 15b, 23 and 24,

endless belts

210, 212 are driven, respectively, at one end, by belt pulleys 214, 216, keyed, respectively, to

shafts

58, 60 and at their opposite ends, by

belt pulleys

218, 220, keyed, respectively, to

shafts

222, 224. As best shown in FIGS. 23, 24, but 212,

intermediate pulleys

216, 220, is supported on rollers 226 and roller guides 228 and belt 210, intermediate pulleys 214, 228, is urged toward belt 212 by rollers 230 and roller guides 232, mounted on the frame and urged toward belt 212 by spring 234.

Referring to FIGS. 14c, 15b, 25 and 26, upper embossing roll 240, having a knurled or roughened surface 242 and embossing disc 244, having a radius slightly longer than the radius of embossing roll 240, are mounted on shaft 246, rotatably supported at its opposite ends, in

supports

248, 250, spring urged by spring 251, downwardly toward spaced

rollers

252, 254, having knurled or roughened surfaces, mounted on shaft 256. As best shown in FIG. 27, embossing roll 240 is fixed to shaft 246 by clamp 258 and screw 260. Embossing disc 244 is mounted for rotation on shaft 246 on hearing 262 and is urged by spring 264, FIG. 25, toward embossing roll 240. Thus, the outer end of disc 244 extending beyond roll 240 rotates between

rollers

252, 254, for reasons more apparent hereinafter.

Referring, next, to FIGS. 29 to 34, the bag end folder includes a bottom bag wall engaging plate, generally designated 270, having a bottom wall 272, and a side wall 274, sloping upwardly in the direction of bag travel through the machine, and guide 276 curving downwardly toward bottom wall 272 in the direction of bag travel and then parallel with bottom wall 272. Upper bag wall engaging plate 278 is positioned at the end of guide 276 and extends longitudinally along the path of bag travel from the end of guide 276.,Flap-engaging plate 280, sloping downwardly in the direction of bag travel toward bottom wall 272 is mounted at the end of plate 270 and, as will be more apparent hereinafter, receives the bag with the end partially folded and, with plate 276, doubles the folded end of the bag onto the bag to form a square, folded closure at the bag end. 1

Referring to FIGS. 14c and 35, rollers 282', 284, having roughened or knurled surfaces are fixed, respectively, to shafts-286, 288. Roller 282 is urged toward roller 284 by spring 285,

Gears

290, 292, keyed to

shafts

286, 288, respectively, intermesh and are driven by. chain 294 and sprocket 296 keyed to shaft 288. As will be later described and as shown in FIG. 36, after passing between

rollers

282, 284, the square, folded closure at the bag end is flat and ready to receive the closure tape.

As shown in FIGS. 14c and 15b, the tape applicator generally designated 40, is mounted at the discharge end of the machine. Referring to FIG. 37, tape'applicator 40 includes frame 300 mounted on machine frame 32 and shoes 302, of which there are three, fixed to frame 300. For reasons more apparent hereinafter, shoes 302 having heating means, not shown, for heating the shoes and, in turn, heating the tape, as it is fed over the shoes. Tape guides 304, 306, 308, 310 are fixed, respectively, to

plates

312, 314, 316, 318 attached by

links

320, 322, 324, 326, to actuator plate 328 mounted for rotation about shaft 330 on frame 300. Referring to FIG. 14c, actuator plate 328 is reciprocated about shaft 300 by piston rod 332 of cylinder 334 connected to plate 328 by arm 336. As shown in FIG. 37, tape guides304, 306, 308 310 are retracted and tape 340 is against shoes 302. When actuated by piston rod 332 and cylinder 334, guides 304, 306, 308, 310 are advanced outwardly, away from shaft 330, lifting .tape 340 off of heated shoes 302 for reasons more apparent hereinafter.

Guide roll 342 is mounted for rotation on frame 300. Drag brake 346, urged into engagement with tape 340 on guide roll 342 by spring 346, adjustable by locking nuts 348, is mounted in fixed position on frame 300.

Knife wheels

350, 352 are fixed to

shafts

354, 356 mounted for rotation in frame 300. Intel-meshing gears 358, 360, FIG. 14c, keyed to

shafts

354, 356,

respectively, drive

knife wheels

354, 356 in the direction of the arrows, FIG. 37. Knife blade 362 is fixed to knife wheel 352. Knife blade 364, as best shown in FIG. 38, ismounted for reciprocation on knife wheel 350, in knife guide 365, being reciprocated back-and-forth, for purposes more apparent hereinafter, by cylinder 366. As best shown in FIGS. 42, 43 and 44-, knife guide 365 extends downwardly beyond the cutting edge of reciprocating knife blade 364 todepress the trailing edge of the bag, while the applied tape is being cut. As best shown in FIGS. 39 and 40, guide 310 has pins 368, spring urged, by spring 370, into engagement with the surface of tape so that, when guides 304, 306, 308, 310 are advanced outwardly, away from shaft 330 to lift tape 340 off of heated shoes 302, the ends of pins 368 engage the tape and hold the tape.

The tape is applied to the folded end of the bag as the bag advances through tape applicator 40. The bag is fed into position at applicator 40 by rollers 382, 384. The side of tape 340 which, when the tape is applied to the bag, will be in contact with the bag paper is coated with a thermoplastic adhesive and, because of the feed and guide arrangement in applicator 40, the uncoated side of tape 340 engages heated shoes 302. Thus, the thermoplastic coating is heated from the reverse side of tape 340 so that, when applied to the bag, the coating is soft and tacky.

As the leading edge of the bag enters applicator 40, the cut end of the tape, at

knife wheels

350, 352, which are rotating, engages the leading end of the bag. As best shown in FIGS. 42 and 43, the flat portion of knife wheels 3 50 and 352 are in opposed position as knife member 362 and reciprocating knife 364 cuts the end of the tape on the preceding bag. The leading edge of the following bag, advanced and'positio'ned by rollers 382, 384, is in position, so that the circular portion of the periphery of

knife wheels

350, 352, after the opposing flat portions of the wheels pass, engage and feed the bag through applicator 40, pressing the heated, thermoplastic coated tape into adhesive engagement with the bag and advances the bag between driven,

mating feed rollers

390, 392, FIG. 37, which, like rollers 382, 384, feed the bag out of tape applicator 40. As the bag is being fed,

knife wheels

350, 352 are rotating so that, when the trailing edge of the bag is properly positioned, knife guide 365 on knife wheel 350 depresses the trailing edge. The tape is then cut by reciprocating knife 364.

Mating feed rollers

390, 392 are identical to feed rollers 382, 384 and, in addition to feeding the sealed, folded and taped end bag, press the tape into adhesive contact with the bag. The thermoplastic adhesive on the tape is cooled as it passes between rollers 382, 384 to assist in holding the tape to the bag. The bags, as discharged from rollers 382, 384 are complete.

In the operation of the apparatus of the instant application, the bag blanks are formed on conventional tubing equipment. The ply sheets, suitably coated, are superimposed, folded, longitudinally seamed and cut into the desired lengths. In superimposing the ply sheets, the water-resistant adhesive is ap plied in the above described pattern of dots and blocks and the sheets are adhesively secured together.

The adhesive pattern of dots and blocks is, of course, applied at the required locations and distances from the bottom edge of the bag blanks.

The bag blanks are fed, one by one, through the apparatus of the instant invention, from the left to right of FIGS. 140, 14c and 15a, 1512, with the bottom edge of the bag to be heated, sealed, folded and taped at the bottom of the apparatus as shown in FIGS. 14a and 14b; Preferably, in feeding the bags through the apparatus, the bags are spaced with the leading edge of one bag away from the trailing edge of the preceding bag by at least inch.

As the bags are advanced through. the apparatus, upper heater head 102 and lower heater head are in the position shown in FIG. 17 so that, as the end of the: bag passes between

heat sinks

104, 122, the thermoplastic material on the inner surface of the inner ply is heated to-a temperature so that the thermoplastic coating is soft and tacky. The heat required to elevate the temperature of such coating,through the thickness of the plies would, if the bags remained stationary in heater section 34, cause the bags to burn. In order to eliminate such burning should it be necessary to stop the machine with bags in heater section 34, heater heads 102, 120 are mounted for rotation about

shafts

116, 134, in the manner hereinbefore described, and, by actuating cylinder and piston 142 heater heads I02, 120 may be moved away from the bag should the apparatus stop or become jammed. Cylinder 140 may be actuated automatically or, manually by the operator.

With the apparatus in operation, heater heads 102, 120 in the position shown in FIG. 17 and the portion of the bags between

heat sinks

104, 122 heated, the bags are advanced out of heater section 34 into sealing section 36. In the apparatus,

heat sinks

104, 122, in heater section 34, are aligned with pressure wheels 178, and sealing wheels 182, 184 so that the outer rounded surface 196 of the intermediate element 194 on sealing wheels 182, 184 contact and compress the plies in the area where the thermoplastic coating on the inner surface of the inner plies has been heated and softened by

heat sinks

104, 122. Thus, the coating on the inner surface of the inner ply is sealed along band a, FIGS. 28, 36, 41.

With the inner ply sealed along band a, the bag then passes between

endless belts

210, 212,

belts

210, 212 compressing the plies together, holding the heated thermoplastic coating along the inner plies at the band a in contact with each other until the thermoplastic material cools, hardens and the seal formed along the band a hardens or is cured. The bag then passes between

rollers

240, 252, 254 where the end of the bag is embossed along the line where the bag is to be folded. As

best shown in H0. 28 the embossing line, designated b, is spaced from seal a so that, when folded along embossed line b, seal a will be in the folded, flap portion of the bag spaced upwardly, on the flap, from the fold line. After the bag end is embossed along fold line b, the end of the bag passes into folding section 38. The bottom of the bag, between embossed line b and the bag end advances up the sloping portion of sidewall 274 of plate 270 folding the flap upwardly and backwardly onto the upper surface of the bag. Plate 278 folds the bag, along embossed line b, against sidewall 274 so that, when folded over into its final position by flap-engaging plate 280, the flap is of uniform height across the width of the bag and the bag end is square. The bag end, with the inner ply sealed and the end folded, then moves into

rollers

282, 284 which compress the flap and feed the bag to tape applicator 40 so that the leading edge of the bag is in position to engage the cut end of the tape in applicator 4i) and to be engaged by

knife wheels

250, 252 as the wheels rotate.

The tape is applied to the end of the bag as hereinabove described and, when discharged from the end of the apparatus by

feed rollers

390, 392, tape 340 is applied and adhesively secured to the flap end of the bag as best shown in FIG. 41. While the machine is run, bags are being fed through the machine and tape is being applied, tape guides 304, 306, 308

and 310 are in the position shown in FIG. 37. If, during the operation of the machine, feed of the bags is stopped, tape guides 304, 306, 308, 310 are actuated outwardly away from shaft 330 to avoid overheating of tape 340 and over-softening of the thermoplastic adhesive thereon.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of exeluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible.

We claim:

1. A multi-ply paper bag having a thermoplastic coating on the inner surface of the innermost ply, a flap at the bottom of said bag extending across the bottom thereof and forming a closure therefor, said flap extending from one side edge of said bag to the other side edge and from the bottom of said bag,

when said bag is laid flat, up one sidewall of said bag and a tape across said flap adhesively secured to said flap and to said one sidewall of said bag, said tape covering the ply ends in said flap, said thermoplastic coating on the inner surface of the innermost ply on the opposite sidewalls of said bag in said flap being joined to form a seal along a line extending across said bag in said flap from one side edge of said bag to the other side ujge.

2. A multi-ply paper bag, as recited in claim 1, in which said inner ply is joined to an outer ply by a water-resistant adhesive along a line in said flap.

3. A multi-ply paper bag, as recited in claim 2, in which said line of water-resistant adhesive is discontinuous.

4. A multi-ply paper bag, as recited in claim 3, in which the outer surface of the outer ply is water repellent.

5. A multi-ply paper bag, as recited in claim 4, in which said thermoplastic coating of the inner surface of the innermost ply is polyethylene.

6. A two-ply gusseted paper bag having an outer ply and an inner ply, a thermoplastic coating-on'the inner surface of the inner ply, a flap at the bottom of said bag extending across the bottom thereof and forming a closure therefor, said flap extending from one side edge of said bag to the other side edge and from the bottom of said bag, when said bag is laid flat, up one sidewall of said bag and a tape across said flap adhesively secured to said flap-and to said one sidewall of said bag, said tape covering the ply ends in said flap, said thermoplastic coating on the inner surface of the inner ply on the opposite sidewalls of said bag in said flap being joined to form a seal along a line extending across said bag in said flap from one side edge of said bag to the other side edge. i

7. A multi-ply paper bag, as recited in claim 6, in which said inner ply is joined to an outer ply by a water-resistant adhesive along a line in said flap.

8. A multiply paper bag, as recited in claim 7, in which said line of water-resistant adhesive is discontinuous.

9. A multi-ply paper bag, as recited in claim 8, in which the outer surface ofthe outer ply is water repellent.

10. A multi-ply paper bag, as recited in claim 9, in which said thermoplastic coating of the inner surface of the inner ply is polyethylene.

Claims

1. A multi-ply paper bag having a thermoplastic coating on the inner surface of the innermost ply, a flap at the bottom of said bag extending across the bottom thereof and forming a closure therefor, said flap extending from one side edge of said bag to the other side edge and from the bottom of said bag, when said bag is laid flat, up one sidewall of said bag and a tape across said flap adhesively secured to said flap and to said one sidewall of said bag, said tape covering the ply ends in said flap, said thermoplastic coating on the inner surface of the innermost ply on the opposite sidewalls of said bag in said flap being joined to form a seal along a line extending across said bag in said flap from one side edge of said bag to the other side edge.

6. A two-ply gusseted paper bag having an outer ply and an inner ply, a thermoplastic coating on the inner surface of the inner ply, a flap at the bottom of said bag extending across the bottom thereof and forming a closure therefor, said flap extending from one side edge of said bag to the other side edge and from the bottom of said bag, when said bag is laid flat, up one sidewall of said bag and a tape across said flap adhesively secured to said flap and to said one sidewall of said bag, said tape covering the ply ends in said flap, said thermoplastic coating on the inner surface of the inner ply on the opposite sidewalls of said bag in said flap being joined to form a seal along a line extending across said bag in said flap from one side edge of said bag to the other side edge.

9. A multi-ply paper bag, as recited in claim 8, in which the outer surface of the outer ply is water repellent.